Chemical,heroid,Ti.Abstract,Seed
Arsenic,362553,"Trace elements in sawdust particles in the vicinity of sawmill in Sapele, Nigeria Abstract: This study report the results of determination of concentrations of lead, cadmium, chromium, barium, arsenic and mercury in sawdust particles collected in the vicinity of wood sawmill in Sapele, Nigeria and its environs. The mean levels of the elements observed ranged from 40-250 mg kg-1 for Pb; 0.50 mg kg-1 for Cd; 1.46-160.50 mg kg-1 for Cr; 1.50-94.0 mg kg-1 for Ba; 32.0-84.0 mg kg-1 for As and 0.50-40 mg kg-1 for Hg. The levels of these trace elements observed in the sawdust particles exceeded permissible occupational exposure limits. Sawdust particles constitute serious health risk to human and the environment in general.",
Arsenic,2088541,"Chemical and pharmacological standardization of Ashwagandhadi lehyam: an ayurvedic formulation Abstract: Standardization is an important measurement for ensuring the quality control of herbal drugs. It has become essential to develop reliable, specific and sensitive quality control methods. One of the prime ingredients of Ashwagandhadi lehyam is Withania somnifera L. Dunal (Solanaceae) (ashwagandha). In the present study, Ashwagandhadi lehyam was formulated and the quality assessment of the formulation was based on phytochemical screening and physico-chemical evaluation. Ashwagandhadi lehyam was formulated according to a working formula and subjected to phytochemical screening by FTIR analysis and HPTLC fingerprinting, heavy metal determination by AAS, determination of alcohol content, tested for Escherichia coli, Staphylococcus aureus, aerobic bacteria, yeasts and mould, oral toxicity studies and anti-epileptic activity by MES method. The physico-chemical studies showed total ash content as 6.45%, extractive values and some trace elements such as lead, mercury, cadmium and arsenic with 3.2, 0.05, 0.18 and 0.48 ppm, respectively. FTIR and HPTLC studies revealed the presence of functional groups of withanolides in Ashwagandhadi lehyam, resulting in its chemical standardization. The formulation exhibited less epileptic seizures in various phases when compared with that of standard phenytoin and found to possess better anti-inflammatory activity, thus making it biologically standardized. The physico-chemical and pharmacological analysis to standardize Ashwagandhadi lehyam confirmed its use as a safe anti-inflammatory agent and for various seizure disorders.",
Arsenic,1519220,"Effects of synthetic chelators and low-molecular-weight organic acids on chromium, copper, and arsenic uptake and translocation in maize (Zea mays L.) Abstract: Chelate-assisted phytoextraction is a promising technique to remediate metal-contaminated soil. Batch and greenhouse experiments were conducted to assess the effects of synthetic chelators (ethylenediaminetetraacetic acid [EDTA], ethylenediaminedisuccinic acid [EDDS], and nitrilotriacetic acid) and low-molecular-weight organic acids (oxalic and citric acids) on the solubilization of copper, chromium, and arsenic (Cu, Cr, and As, respectively) in chromated Cu arsenate (CCA)-contaminated soil and on metal uptake and translocation in maize (Zea mays L.). Chelators significantly enhanced the solubilization of Cr, Cu, and As in the soil and markedly increased their accumulation in plant tissues. Applying 5 and 10 mmol kg?1 EDDS increased plant Cu uptake by 2.8- and 3.5-fold greater than that in control soil (without chelate applications), respectively. EDTA and citric acid were more efficient for increasing Cr uptake by plant shoots, resulting in 5.0- and 5.5-fold increases, respectively, compared with that in the control. Maximum As uptake was observed in response to a treatment of 10 mmol kg?1 citric acid, which was 1.9-fold greater than that in control soil. However, translocation factors, phytoextraction efficiencies, and remediation factors indicated that metal uptake was not high enough for successful phytoremediation of CCA–contaminated soil. Our results suggest that EDDS and citric acid as alternatives to EDTA may facilitate phytoextraction of contaminated soil.",
Arsenic,1354192,Mineralogical associations of arsenic and antimony in thirty five geochemical reference materials by sequential extraction with hydride generation and atomic absorption spectrometry Abstract: ,
Arsenic,1579337,"In vitro toxicological characterization of two arsenosugars and their metabolites Abstract: SCOPE: In their recently published Scientific Opinion on Arsenic in Food, the European Food Safety Authority concluded that a risk assessment for arsenosugars is currently not possible, largely because of the lack of relevant toxicological data. To address this issue, we carried out a toxicological in vitro characterization of two arsenosugars and six arsenosugar metabolites. METHODS AND RESULTS: The highly pure synthesized arsenosugars, DMA(V) -sugar-glycerol and DMA(V) -sugar-sulfate, investigated in this study, as well as four metabolites, oxo-dimethylarsenoacetic acid (oxo-DMAA(V) ), oxo-dimethylarsenoethanol (oxo-DMAE(V) ), thio-DMAA(V) and thio-DMAE(V) , exerted neither cytotoxicity nor genotoxicity up to 500 ?M exposure in cultured human bladder cells. However, two arsenosugar metabolites, namely dimethyl-arsinic acid (DMA(V) ) and thio-dimethylarsinic acid (thio-DMA(V) ), were toxic to the cells; thio-DMA(V) was even slightly more cytotoxic than arsenite. Additionally, intestinal bioavailability of the arsenosugars was assessed applying the Caco-2 intestinal barrier model. The observed low, but significant transfer rates of the arsenosugars across the barrier model provide further evidence that arsenosugars are intestinally bioavailable. CONCLUSION: In a cellular system that metabolizes arsenosugars, cellular toxicity likely arises. Thus, in strong contrast to arsenobetaine, arsenosugars cannot be categorized as nontoxic for humans and a risk to human health cannot be excluded.",
Arsenic,1351860,"ELECTROPHILE AND ANTIOXIDANT REGULATION OF ENZYMES THAT DETOXIFY CARCINOGENS Abstract: Detoxication (phase 2) enzymes, such as glutathione S-transferases (GSTs), NAD(P)H:(quinone-acceptor) oxidoreductase (QR), and UDP-glucuronsyltransferase, are induced in animal cells exposed to a variety of electrophilic compounds and phenolic antioxidants. Induction protects against the toxic and neoplastic effects of carcinogens and is mediated by activation of upstream electrophile-responsive/antioxidant-responsive elements (EpRE/ARE). The mechanism of activation of these enhancers was analyzed by transient gene expression of growth hormone reporter constructs containing a 41-bp region derived from the mouse GST Ya gene 5'-upstream region that contains the EpRE/ARE element and of constructs in which this element was replaced with either one or two consensus phorbol 12-tetradecanoate 13-acetate (TPA)-responsive elements (TREs). When these three constructs were compared in Hep G2 (human) and Hepa 1c1c7 (murine) hepatoma cells, the wild-type sequence was highly activated by diverse inducers, including tert-butylhydroquinone, Michael reaction acceptors, 1,2-dithiole-3-thione, sulforaphane,2,3-dimercapto-1-propanol, HgCl2, sodium arsenite, and phenylarsine oxide. In contrast, constructs with consensus TRE sites were not induced significantly. TPA in combination with these compounds led to additive or synergistic inductions of the EpRE/ARE construct, but induction of the TRE construct was similar to that induced by TPA alone. Transfection of the EpRE/ARE reporter construct into F9 cells, which lack endogenous TRE-binding proteins, produced large inductions by the same compounds, which also induced QR activity in these cells. We conclude that activation of the EpRE/ARE by electrophile and antioxidant inducers is mediated by EpRE/ARE-specific proteins.",
Arsenic,628810,"Assessing the measurement precision of various arsenic forms and arsenic exposure in the National Human Exposure Assessment Survey (NHEXAS) Abstract: Archived samples collected from 1995 to 1997 in the National Human Exposure Assessment Survey (NHEXAS) in U.S. Environmental Protection Agency Region 5 (R5) and the Children's Study (CS) in Minnesota were analyzed for total arsenic, arsenate [As(V)], arsenite, dimethyl arsenic acid (DMA), monomethyl arsenic acid (MMA), arsenobetaine (AsB), and arsenocholine. Samples for the CS included drinking water, urine, hair, and dust; both studies included food (duplicate plate, composited 4-day food samples from participants). Except for AsB and As(V), the levels for As species measured in the food and drinking water samples were very low or nonexistent. The analytical methods used for measuring As species were sensitive to < 1 ppb. During the analysis of food and drinking water samples, chromatographic peaks appeared that contained As, but they did not correspond to those being quantified. Thus, in some samples, the sum of the individual As species levels was less than the total As level measured because the unknown forms of As were not quantified. On the other hand, total As was detectable in almost all samples (> 90%) except for hair (47%), indicating that the analytical method was sufficiently sensitive. Population distributions of As concentrations measured in drinking water, food (duplicate plate), dust, urine, and hair were estimated. Exposures to total As in food for children in the CS were about twice as high as in the general R5 population (medians of 17.5 ppb and 7.72 ppb, respectively). In addition, AsB was the most frequently detected form of As in food eaten by the participants, while As(V) was only rarely detected. Thus, the predominant dietary exposure was from an organic form of As. The major form of As in drinking water was As(V). Spearman (rank) correlations and Pearson (log-concentration scale) correlations between the biomarkers (urine, hair) and the other measures (food, drinking water, dust) and urine versus hair were performed. In the NHEXAS CS, total As and AsB in the food eaten were significantly correlated with their levels in urine. Also, levels of As(V) in drinking water correlated with DMA and MMA in urine. Arsenic levels in dust did not show a relationship with urine or hair levels, and no relationship was observed for food, drinking water, and dust with hair. Urine samples were collected on days 3, 5, and 7 of participants' monitoring periods. Total As levels in urine were significantly associated across the three pairwise combinations--i.e., day 3 versus day 5, day 3 versus day 7, and day 5 versus day 7. Because the half-life of As in the body is approximately 3 days, this suggests that some exposure occurred continually from day to day. This trend was also observed for AsB, suggesting that food is primarily responsible for the continual exposure. DMA and MMA in urine were also significantly correlated but not in all combinations.",
Arsenic,1015701,"Health status of red mullets from polluted areas of the Spanish Mediterranean coast, with special reference to Portmán (SE Spain) Abstract: A suite of general physiological indicators and hepatic biomarker responses were determined in red mullet (Mullus barbatus) from priority pollution areas of W Mediterranean Sea, including the highly metal polluted area of Portmán (Cartagena, SE Spain). Concentrations of metals and persistent organic pollutants in fish muscle tissue and sediment samples were also analysed. Our results showed that fish from Portmán accumulated the highest concentrations of mercury, lead and arsenic and also of some polycyclic aromatic hydrocarbons and polychlorinated biphenyls congeners. In addition, they had significantly lower condition factor, muscle lipid content and gonadosomatic index, as well as the lowest levels of DNA integrity and the highest ethoxyresorufin-O-deethylase (EROD) activity in liver of the areas investigated. Contaminant body burden in fish only partly corresponded to chemical characteristics of the sediments in the areas in which they were collected. Our findings indicate that red mullets from Portmán had suboptimal health status that warrant further study.",
Arsenic,2343431,"Using portable X-ray fluorescence spectrometry and GIS to assess environmental risk and identify sources of trace metals in soils of peri-urban areas in the Yangtze Delta region, China Abstract: Portable X-ray fluorescence (PXRF) spectrometry may be very suitable for a fast and effective environmental assessment and source identification of trace metals in soils. In this study, topsoils (0-10 cm) at 139 sites were in situ scanned for total trace metals (Cr, Cu, Ni, Pb and Zn) and arsenic concentrations by PXRF in a typical town in Yangtze Delta region of Jiangsu province, China. To validate the utility of PXRF, 53 samples were collected from the scanning sites for the determination of selected trace metals using conventional methods. Based on trace metal concentrations detected by in situ PXRF, the contamination extent and sources of trace metals were studied via geo-accumulation index, multivariate analysis and geostatistics. The trace metal concentrations determined by PXRF were similar to those obtained via conventional chemical analysis. The median concentration of As, Cr, Cu, Ni, Pb and Zn in soils were 10.8, 56.4, 41.5, 43.5, 33.5, and 77.7 mg kg(-1), respectively. The distribution patterns of Cr, Cu, Ni, Pb, and Zn were mostly affected by anthropogenic sources, while As was mainly derived from lithogenic sources. Overall, PXRF has been successfully applied to contamination assessment and source identification of trace metals in soils.",
Arsenic,1341658,"Synergy between cisplatin and an inhibitor of S-adenosylmethionine dependent transmethylation in human ovarian adenocarcinoma cells Abstract: Selection of cells for resistance to cisplatin results in resistance to arsenite and selenite. Mammalian cells detoxify arsenite and selenite by S-adenosylmethionine dependent methylation. We aimed to investigate whether S-adenosylmethionine dependent methylation is involved in the cellular metabolism of cisplatin. Treatment of human ovarian cancer cells 2008 and the cisplatin-resistant subline 2008/C13*5.25 with the S-adenosylhomocysteine hydrolase inhibitor adenosine-dialdehyde, an indirect inhibitor of transmethylation, resulted in a significant elevation (16-fold in 2008, 6-fold in 2008/C13*5.25) in the cellular content of S-adenosylhomocysteine without changing S-adenosylmethionine. Adenosine dialdehyde synergistically enhanced the cytotoxicity of cisplatin and carboplatin as evidenced by combination indices &lt;1 using the combination index-isobologram method in clonogenic assays with 2008 human ovarian adenocarcinoma cells. However, the cellular accumulation, efflux, steady state content, and the formation of DNA adducts of the cisplatin [H-3]-DEP were not affected by adenosine-dialdehyde. Sodium arsenite was significantly more toxic in mice pretreated with adenosine-dialdehyde, whereas the toxicity of cisplatin remained unchanged. These studies suggest that inhibition of S-adenosylmethionine dependent transmethylation enhanced the toxicity of cisplatin and carboplatin to human ovarian carcinoma cells in vitro without directly affecting the metabolism of either platinum drug.",
Arsenic,1356833,"Arsenic stimulates pro-angiogenic gene expression and changes in vascular architecture in the liver Abstract: Arsenic is a well known environmental toxicant that causes a wide range of organ specific diseases and cancers. Epidemiological evidence shows that drinking arsenic contaminated water causes vascular remodeling in humans and contributes to the pathogenesis of liver diseases through poorly defined mechanisms. Chronic low level exposures to arsenic in mice enhanced angiogenesis and vascular remodeling. Therefore, we examined the hypothesis that environmentally-relevant exposures to arsenic promote a program of vascular gene changes in the liver that increases vessel density and changes vessel structure. Mice were exposed to 0, 50 ppb, 250 ppb, and 500 ppb of sodium arsenite (AsIII) in their drinking water for five weeks. After euthanasia, livers were excised and snap-frozen for quantitative measurements of angiogenic mRNA levels and immunofluorescent localization of protein expression. Quantitative RT-PCR of total liver RNA demonstrated that 250 ppb of As(III) significantly increased levels of pro-angiogenic VEGF-R1, VEGF-R2, Tie-2, Ang-1 and Ang-2, relative to changes in the HPRT mRNA levels. Immunofluorescent analysis of 10-micron frozen/fixed tissue sections demonstrated increased angiogenic protein expression that was localized to an increased number of sinusoidal vessels and that there were substantial changes in sinusoid morphology. Stimulation of a broad program of angiogenesis and remodeling may explain the complex role As(III) plays in the progression of organ specific disease, such as liver hepatomeglia, fibrosis, and possibly cancer.",
Arsenic,656808,"Markers of low level arsenic exposure for evaluating human cancer risks in a US population Abstract: Epidemiologic studies conducted in the US have not previously detected an association between regional drinking water arsenic concentrations and corresponding cancer occurrence or mortality rates. To improve our estimation of cancer risk and arsenic exposure in the USA, we have investigated the reliability of several exposure markers. In the current study, we specifically evaluated the long-term reproducibility of tap water and toenail concentrations of arsenic, and the relation between water, toenail, and urinary measurement. Subjects included 99 controls in our case-control study on whom we requested a household tap water sample and toenail clipping three to five years apart. Additionally, participants were asked to provide a first morning void sample at the second interview. Tap water arsenic concentrations ranged from undetectable (<0.01 microg/L) to 66.6 microg/L. We found a significant correlation between both replicate water and toenail samples (intraclass correlation coefficient = 0.85, 95% confidence interval = 0.79-0.89 for water, and intraclass correlation coefficient = 0.60, 95% confidence interval = 0.48-0.70 for toenails). The inter-method correlations for water, urinary and toenail arsenic were all statistically significant (r = 0.35, p = 0.0024 for urine vs water; r = 0.33, p = 0.0016 for toenail vs water and r = 0.36, p = 0.0012 for urine vs toenails). Thus, we found both toenail and water measurements of arsenic reproducible over a three- to five-year period. Our data suggest that biologic markers may provide reliable estimates of internal dose of low level arsenic exposure that can be used to assess cancer risk.",
Arsenic,1250984,"Effects of co-administration of dietary sodium arsenate and 2,3-dimercaptopropane-1-sulfonic acid (DMPS) on the rat bladder epithelium Abstract: Inorganic arsenic is a known human carcinogen, inducing tumors of the skin, urinary bladder and lung. It is metabolized to organic methylated arsenicals. 2,3-Dimercaptopropane-1-sulfonic acid (DMPS), a chelating agent, is capable of reducing pentavalent arsenicals to the trivalent state and binding to the trivalent species, and it has been used in the treatment of heavy metal poisoning in humans. Therefore, we investigated the ability of DMPS to inhibit the cytotoxicity and regenerative urothelial cell proliferation induced by arsenate administration in vivo. Female rats were treated for 4 weeks with 100ppm As(V). DMPS (2800ppm) co-administered in the diet significantly reduced the As(V)-induced cytotoxicity of superficial cells detected by scanning electron microscopy (SEM), and the incidence of simple hyperplasia observed by light microscopy and the bromodeoxyuridine (BrdU) labeling index. It also reduced the total concentration of arsenicals in the urine and the methylation of arsenic. There were no differences in oxidative stress as assessed by immunohistochemical staining for 8-hydroxy-2'-deoxyguanosine (8OHdG) of the bladder urothelium. No differences were detected in urine sediments between groups. These data suggest that DMPS has the ability to inhibit both arsenate-induced acute toxicity and regenerative proliferation of the rat bladder epithelium, most likely by decreasing exposure of the urothelium to trivalent arsenicals excreted in the urine. These data provide additional evidence that the effects of arsenate exposure in vivo do not appear to be related to oxidative effects on dG in DNA.",
Arsenic,628483,"Mechanism of arsenic carcinogenesis: An integrated approach Abstract: Epidemiological evidence shows an association between inorganic arsenic in drinking water and increased risk of skin, lung and bladder cancers. The lack of animal models has hindered mechanistic studies of arsenic carcinogenesis in the past, but some promising new models for these cancers are now available. The various forms of arsenic to which humans are exposed, either directly or via metabolism of inorganic arsenic to various methylated forms, further complicate the issue of mechanism, since these compounds can have different effects, both genotoxic and non-genotoxic. This review will try to integrate all of these issues, with a strong bias toward effects that are produced by environmentally relevant arsenic concentrations.",
Arsenic,1579283,"CD44v6 expression in human skin keratinocytes as a possible mechanism for carcinogenesis associated with chronic arsenic exposure Abstract: Inorganic arsenic is a well-known human skin carcinogen. Chronic arsenic exposure results in various types of human skin lesions, including squamous cell carcinoma (SCC). To investigate whether mutant stem cells participate in arsenic-associated carcinogenesis, we repeatedly exposed the HaCaT cells line to an environmentally relevant level of arsenic (0.05 ppm) in vitro for 18 weeks. Following sodium arsenic arsenite administration, cell cycle, colony-forming efficiency (CFE), cell tumorigenicity, and expression of CD44v6, NF-?B and p53, were analyzed at different time points (0, 5, 10, 15, 20, 25 and 30 passages). We found that a chronic exposure of HaCaT cells to a low level of arsenic induced a cancer stem- like phenotype. Furthermore, arsenic-treated HaCaT cells also became tumorigenic in nude mice, their growth cycle was predominantly in G2/M and S phases. Relative to nontreated cells, they exhibited a higher growth rate and a significant increase in CFE. Western blot analysis found that arsenic was capable of increasing cell proliferation and sprouting of cancer stem-like phenotype. Additionally, immunohistochemical analysis demonstrated that CD44v6 expression was up-regulated in HaCaT cells exposed to a low level of arsenic during early stages of induction. The expression of CD44v6 in arsenic-treated cells was positively correlated with their cloning efficiency in soft agar (r=0.949, P=0.01). Likewise, the expressions of activating transcription factor NF-?B and p53 genes in the arsenic-treated HaCaT cells were significantly higher than that in non-treated cells. Higher expressions of CD44v6, NF-?B and p53 were also observed in tumor tissues isolated from Balb/c nude mice. The present results suggest that CD44v6 may be a biomarker of arsenic-induced neoplastic transformation in human skin cells, and that arsenic promotes malignant transformation in human skin lesions through a NF-?B signaling pathway-stimulated expression of CD44v6.",
Arsenic,2345819,"Toxic metal concentrations in cigarettes obtained from U.S. smokers in 2009: Results from the international tobacco control (ITC) United States survey cohort Abstract: Smoking-related diseases can be attributed to the inhalation of many different toxins, including heavy metals, which have a host of detrimental health effects. The current study reports the levels of arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), and lead (Pb) in cigarettes obtained from adult smokers participating in the 2009 wave of the ITC United States Survey (N = 320). The mean As, Cd, Cr, Ni, and Pb levels were 0.17, 0.86, 2.35, 2.21, and 0.44 µg/g, respectively. There were some differences in metal concentrations of cigarette brands produced by different manufacturers, suggesting differences in the source of tobaccos used by different companies. For Ni, there were significant pairwise differences between Philip Morris U.S. (PMUSA) and R.J. Reynolds (RJR) brands (PMUSA higher; p &lt; 0.001), PMUSA and other manufacturer (OM) brands (PMUSA higher; p &lt; 0.001), and RJR and OM brands (RJR higher; p = 0.006). For Cr, RJR brands had higher levels than did OM brands (p = 0.02). Levels of As, Cd, and Pb did not differ significantly across manufacturer groups (p &gt; 0.10). Because of the variety of toxic heavy metals in cigarette tobacco, and their numerous negative health effects, metal content in cigarette tobacco should be reduced.",
Arsenic,628322,"Oral exposure of dimethylarsinic acid, a main metabolite of inorganic arsenics, in mice leads to an increase in 8-Oxo-2'-deoxyguanosine level, specifically in the target organs for arsenic carcinogenesis Abstract: We have proposed that oral administration of dimethylarsinic acid (DMA), a metabolite of inorganic arsenics in mammals, rather than inorganic arsenics themselves, promotes lung and skin tumors by way of the metabolic production of free radicals such as dimethylarsenic peroxy radical [(CH(3))(2)AsOO*]. The purpose of the present study was to examine if dimethylarsenic has the ability to induce oxidative damage. 8-oxo-2'-deoxyguanosine (8-oxodG) was used as a biomarker of DNA oxidation. The oral administration of DMA enhanced significantly the amounts of 8-oxodG specifically in the target organs (skin, lung, liver, and urinary bladder) of arsenic carcinogenesis and also in urine, whereas arsenite did not. The dimethylarsenics thus may play an important role in arsenic carcinogenesis through the induction of oxidative damage, particularly of base oxidation.",
Arsenic,1508715,"Platelet volume indices have low diagnostic efficiency for predicting bone marrow failure in thrombocytopenic patients Abstract: The aim of the present study was to evaluate the predictive efficiency of mean platelet volume (MPV) and platelet size deviation width (PDW) for bone marrow failure (BMF) in thrombocytopenic patients. Platelet count, MPV and PDW data were retrieved from the records of 574 unselected thrombocytopenic patients from between March 2010 and March 2011, of which 182 patients with a platelet count &lt;20×10(9)/l were excluded from further study. A total of 392 valid thrombocytopenic patients were included in the present study and divided into two groups: 124 patients with idiopathic thrombocytopenia purpura (ITP) and 268 with BMF. The predictive efficiency of MPV and PDW were tested for the diagnosis of BMF. Significant differences were observed in the age distribution, platelet count, MPV and PDW between the ITP and BMF groups. The platelet count was positively correlated with MPV and PDW in the patients with ITP but not BMF. The negative-predictive values of MPV and PDW for BMF were 59.3 and 58.9%, respectively, with an MPV threshold of ?11.0 fl and a PDW threshold of &lt;16.0%. The positive-predictive values of MPV and PDW for BMF were 88.4 and 83.9%, respectively, with an MPV threshold &lt;8.0 fl and a PDW threshold ?17.5%. The areas under the curves (AUCs) of MPV and PDW were 0.281 and 0.700, respectively, for the diagnosis of BMF. The negative and positive-predictive values of MPV for BMF at different thresholds were not as conclusive as described in previous studies. MPV and PDW do not have sufficient specificity and sensitivity for the diagnosis of BMF in thrombocytopenic patients.",
Arsenic,2278252,"Beta-catenin is activated in arsenic-transformed human bronchialepithelial cells and promotes angiogenesis Abstract: Arsenic exposure represents a major health concern causing human cancers, yet the mechanism of arsenic carcinogenesis has not been elucidated. We and others recently reported that cell malignant transformation by arsenic is accompanied by epithelial to mesenchymal transition (EMT). However, the role of EMT in arsenic carcinogenesis is not well understood. Although previous studies showed that acute short term arsenic treatment stimulates angiogenesis, it remains to be determined whether cells that were malignantly transformed by long term arsenic exposure have a pro-angiogenic effect. The objective of this study was to investigate the effect of arsenic-transformed human bronchial epithelial cells that underwent EMT on angiogenesis and the underlying mechanism. It was found that the conditioned medium from arsenic-transformed cells strongly stimulated tube formation by human umbilical vein endothelial cells (HUVECs). Moreover, enhanced angiogenesis was detected in mouse xenograft tumor tissues resulting from inoculation of arsenic-transformed cells. Mechanistic studies revealed that ?-catenin was activated in arsenic-transformed cells up-regulating its target gene expression including angiogenic-stimulating vascular endothelial growth factor (VEGF). Stably expressing microRNA-200b in arsenic-transformed cells that reversed EMT inhibited ?-catenin activation, decreased VEGF expression and reduced tube formation by HUVECs. SiRNA knocking down ?-catenin decreased VEGF expression. Adding a VEGF neutralizing antibody into the conditioned medium from arsenic-transformed cells impaired tube formation by HUVECs. It was further determined that the canonical Wnt signaling was not increased in arsenic-transformed cells. These findings suggest that EMT in arsenic-transformed cells promotes angiogenesis through activating ?-catenin-VEGF pathway in the absence of elevated-canonical Wnt signaling.",
Arsenic,627949,"Lack of promoting effect due to oral administration of dimethylarsinic acid on rat lung carcinogenesis initiated with N-bis(2-hydroxypropyl)nitrosamine Abstract: Dimethylarsinic acid (DMA), a major metabolite of inorganic arsenics, and arsenic exposure is associated with tumor development in a wide variety of human tissues. In the present study, we examined whether DMA has tumor-promoting activity on rat lung carcinogenesis initiated with N-bis(2-hydroxypropyl)nitrosamine (DHPN). Male, 8-week-old, F344 rats were treated with DHPN at a concentration of 0.1% in drinking water for 1 week, and starting 1 week thereafter, DMA was administered at concentrations of 0, 100, 200 or 400 ppm in the drinking water for 30 weeks. Induction of epithelial lesions, classified as alveolar epithelial hyperplasia, adenoma, and adenocarcinoma was evident in the lungs of DHPN-initiated animals, but no significant differences were found between DMA-treated groups and control groups. Furthermore, no significant differences in 5-bromo-2'-deoxyuridine labeling indices, as a marker of cell proliferation were observed among the groups. An additional group treated with DMA at concentrations of 200 ppm alone, without prior DHPN initiation was found to develop no epithelial lesions in the lung. There was no significant gain in 8-hydroxydeoxyguanosine formation, as a marker of oxidative stress, in the lungs of rats treated with DMA in their drinking water. In conclusion, oral-administered DMA does not exert promoting effects on rat lung carcinogenesis initiated with DHPN.",
Arsenic,1519131,"Airborne trace metals from coal combustion in Beijing Abstract: Prior studies have measured elevated ambient concentrations of hazardous metals in Beijing, attributable to coal combustion. The 2008 Olympic Games led to an intense investment in air pollution controls at the major power plants in the region, accounting for 30% of coal combustion in Beijing. Recently Chinese coal beds have been characterized in the World Coal Quality Index, facilitating the development of trace metal emission factors for Beijing coals. This study quantifies the relative value of the power plant air pollution controls in terms of public health risk from chronic exposure to trace metals. Ambient concentrations from power plants were estimated using an atmospheric dispersion model (CALPUFF), outlining spatial and temporal variations. The following toxic, refractory metals were evaluated for health risk using the USEPA Integrated Risk Information System: antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, nickel, and selenium. Stringent use of power plant air pollution controls significantly reduces population risk, averting a cancer risk of 1 in 5,000. However, other sources of coal combustion, such as industrial and household uses, are more relevant to public health than power plant emissions. Coal washing has potential to reduce the hazard from these diffuse sources and avert a greater number of potential cancer cases.",
Arsenic,506479,"Determination of heavy metals in water from boreholes in Dumasi in the Wassa West District of western region of Republic of Ghana Abstract: Concentrations of heavy metals in the borehole at Dumasi in the Wassa West District of the Republic of Ghana have been measured in this study. The concentrations of the following metals in the ground water from Dumasi borehole are: Iron (Fe) - 7.52 ppm, Manganese (Mn) - 1.11 ppm, Arsenic (As) - 4.52 ppm, Chromium (Cr) - 0.026 ppm, Cobalt (Co) - 0.01 ppm, Zinc (Zn) - 0.007 ppm, Cadmium (Cd) - 0.002 ppm and Lead (Pb) - 0.005 ppm. The results of the study show that resident adults and children who use water from the boreholes are at serious risk from exposure to health hazards associated with exposure to the above metals in the boreholes in Dumasi. If the results of this study are applied to other mining communities, which lie on the Birimian and Tarkwaian rock system, then the residents are at serious risk from exposure to toxic metals from drinking water from the boreholes dug for them by mining companies operating in their communities.",
Arsenic,2345850,"Association between arsenic exposure and diabetes mellitus in Cambodia Abstract: Whereas studies in Taiwan found associations between arsenic exposure from drinking water and diabetes mellitus (DM), studies in other countries yielded inconsistent results, and diet might be a confounder. We conducted a study in Cambodia, where people have non-Western style diet, to evaluate the association. We measured well water and urine samples and examined skin signs of arsenicosis to assess arsenic exposure and used questionnaires to collect data on potential risk factors. We performed a fingertip blood glucose test followed by measurement of hemoglobin A1c to assess DM. The 43-male and 99-female participants had an average age of 40.4 years. We found that participants with skin signs of arsenicosis had a higher level of arsenic in the drinking water (1101.1 versus 972.2 mu g/L, P = 0.02). Drinking water with arsenic levels above the median (907.25 mu g/L) was associated with a nearly twofold increase in the risk of DM (odds ratio [OR] = 1.7, 95% confidence interval [CI]: 0.5-5.8), so was having skin sings of arsenicosis (OR = 1.7, 95% CI: 0.5-5.6). The ORs did not reach statistical significance most likely because of the small case number. Therefore, further studies with larger study populations are needed to confirm our findings.",
Arsenic,1025287,"Protective effects of hepatocellular canalicular conjugate export pump (Mrp2) on sodium arsenite-induced hepatic dysfunction in rats Abstract: Arsenic is a double-edged sword to human health. The excretion of various organic anions into bile is mediated by an adenosine triphosphate-dependent conjugate export pump, which has been identified as the canalicular isoform of the multidrug resistance protein 2 (Mrp2). It has been proved that Mrp2 can transport arsenite in vitro, but its effects in vivo are not clear. The aim of this study was to investigate whether Mrp2 plays a role in exportation of arsenic in vivo and its protective effects on liver function. Mrp2 protein level in rat liver was determined by Western blot analysis. Total arsenic concentrations in whole blood and bile were measured using hydride generation atomic absorption spectrometry. Alanine aminotransferase (ALT) activity, aspartate aminotransferase activity (AST), glutathione peroxidase (GSH-PX) activity, malon dialdehyde (MDA) and total bilirubin were measured by biochemical assays. The morphological changes were observed by electron microscopy. Total arsenic levels in blood and bile of arsenite-treated rats were significantly higher than those of control rats (P&lt;0.05) at all three different time points. The overexpression of Mrp2 was 36.61%, 32.36% and 12.73% at 2, 4 and 6 weeks, respectively (percentage of controls, P&lt;0.05), which was significantly higher than controls. A positive correlation between Mrp2 expression level and total arsenic concentration in bile indicated that Mrp2 accelerated the transport of arsenic. Electron microscopy showed that microvilli of bile canaliculi became swollen and sparse. ALT and AST activities in serum were markedly raised at 6 weeks. MDA level in serum increased (P&lt;0.05) and GSH-PX activity in serum decreased except for 2 weeks. Damage of liver function became worse following decreased expression of Mrp2. In conclusion, overexpression of Mrp2 may explain increased biliary excretion of arsenic and it may protect liver function.",
Arsenic,2279336,"Cathodic stripping voltammetric determination of arsenic in sugarcane brandy at a modified carbon nanotube paste electrode Abstract: We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110?gL(-1) and from 10 to 110?gL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5?gL(-1) for mineral oil and 3.4 and 11.2?gL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS).",
Arsenic,1357234,"Exposure to Metals at a Scrap Recycling Firm Abstract: This case report evaluated the exposure of workers to lead (7439921), arsenic (7440382), cadmium (7440439), and iron (7439896) during the dismantling and cutting of automobiles at a salvage facility. Blood lead levels of eight workers ranged from 8 to 56 micrograms/deciliter. The worker with the highest level was recommended for removal from the job. Personal air sampling for lead and other metals was done on workers using acetylene torches to cut automobiles. Results from collected filter cassettes worn by workers found that they were exposed to lead, cadmium, and iron-oxide above permissible exposure levels. Lead exposures ranged between 103 to 1,991 micrograms/cubic meter (microg/m3), cadmium exposures between 3.2 to 51.8microg/m3, and iron-oxide (1332372) between 11.4 to 25mg/m3. Investigation of the facility indicated respiratory protection was inadequate for the exposure; special protective clothing apart from street clothes was not worn; showers were not required before leaving the facility; hands were not washed or clothing changed before entering the lunchroom; smoking, eating and drinking were permitted in the work areas; workers were not trained concerning hazards of lead exposure; and exposed workers were not provided with medical monitoring. Inspection resulted in the facility being required to comply with Occupational Safety and Health Administration standards. The investigation also resulted in the development and implementation of comprehensive safety and health programs for workers.",
Arsenic,1022145,"Humans seem to produce arsenobetaine and dimethylarsinate after a bolus dose of seafood Abstract: Seafood is the predominant food source of several organoarsenic compounds. Some seafood species, like crustaceans and seaweed, also contain inorganic arsenic (iAs), a well-known toxicant. It is unclear whether human biotransformation of ingested organoarsenicals from seafood result in formation of arsenicals of health concern. The present controlled dietary study examined the urinary excretion of arsenic compounds (total arsenic (tAs), iAs, AB (arsenobetaine), dimethylarsinate (DMA) and methylarsonate (MA)) following ingestion of a single test meal of seafood (cod, 780 ?g tAs, farmed salmon, 290 ?g tAs or blue mussel, 690 ?g tAs or potato (control, 110 ?g tAs)) in 38 volunteers. The amount of ingested tAs excreted via the urine within 0-72 h varied significantly among the groups: Cod, 74% (52-92%), salmon 56% (46-82%), blue mussel 49% (37-78%), control 45% (30-60%). The estimated total urinary excretion of AB was higher than the amount of ingested AB in the blue mussel group (112%) and also ingestion of cod seemed to result in more AB, indicating possible endogenous formation of AB from other organoarsenicals. Excretion of iAs was lower than ingested (13-22% of the ingested iAs was excreted in the different groups). Although the ingested amount of iAs+DMA+MA was low for all seafood groups (1.2-4.5% of tAs ingested), the urinary DMA excretion was high in the blue mussel and salmon groups, counting for 25% and 11% of the excreted tAs respectively. In conclusion our data indicate a possible formation of AB as a result of biotransformation of other organic arsenicals. The considerable amount of DMA excreted is probably not only due to methylation of ingested iAs, but due to biotransformation of organoarsenicals making it an inappropriate biomarker of iAs exposure in populations with a high seafood intake.",
Arsenic,2279294,"Distribution and genetic diversity of the microorganisms in the biofilter for the simultaneous removal of arsenic, iron and manganese from simulated groundwater Abstract: A biofilter was developed in this study, which showed an excellent performance with the simultaneous removal of AsIII from 150 to 10mgL(-1) during biological iron and manganese oxidation. The distribution and genetic diversity of the microorganisms along the depth of the biofilter have been investigated using DGGE. Results suggested that Iron oxidizing bacteria (IOB, such as Gallionella, Leptothrix), Manganese oxidizing bacteria (MnOB, such as Leptothrix, Pseudomonas, Hyphomicrobium, Arthrobacter) and AsIII-oxidizing bacteria (AsOB, such as Alcaligenes, Pseudomonas) are dominant in the biofilter. The spatial distribution of IOB, MnOB and AsOB at different depths of the biofilter determined the removal zone of FeII, MnII and AsIII, which site at the depths of 20, 60 and 60cm, respectively, and the corresponding removal efficiencies were 86%, 84% and 87%, respectively. This process shows great potential to the treatment of groundwater contaminated with iron, manganese and arsenic due to its stable performance and significant cost-savings.",
Arsenic,1017984,"Genotoxicity surveillance programme in workers dismantling World War I chemical ammunition Abstract: <strong>PURPOSE: </strong>To evaluate the effectiveness of personal protective measures in a dismantling plant for chemical weapons from World War I of the Belgian Defence.<br /><br /><strong>METHODS: </strong>Seventeen NIOSH level B-equipped plant workers exposed to arsenic trichloride (AsCl(3)) in combination with phosgene or hydrogen cyanide (HCN) were compared to 24 NIOSH level C-protected field workers occasionally exposed to genotoxic chemicals (including AsCl(3)-phosgene/HCN) when collecting chemical ammunition, and 19 matched referents. Chromosomal aberrations (CA), micronuclei (MNCB and MNMC), sister chromatid exchanges (SCE) and high frequency cells (HFC) were analysed in peripheral blood lymphocytes. Urinary arsenic levels and genetic polymorphisms in major DNA repair enzymes (hOGG1(326), XRCC1(399), XRCC3(241)) were also assessed.<br /><br /><strong>RESULTS: </strong>SCE and HFC levels were significantly higher in plant-exposed versus referent subjects, but MNCB and MNMC were not different. MNCB, SCE and HFC levels were significantly higher and MNMC levels significantly lower in field-exposed workers versus referents. AsCl(3) exposure was not correlated with genotoxicity biomarkers.<br /><br /><strong>CONCLUSIONS: </strong>Protective measures for plant-exposed workers appear adequate, but protection for field-exposed individuals could be improved.",
Arsenic,1509360,"Analysis of energy sources for Mycoplasma penetrans gliding motility Abstract: Mycoplasma penetrans, a potential human pathogen found mainly in HIV-infected individuals, uses a tip structure for both adherence and gliding motility. To improve our understanding of the molecular mechanism of M. penetrans gliding motility, we used chemical inhibitors of energy sources associated with motility of other organisms to determine which of these is used by M. penetrans and also tested whether gliding speed responded to temperature and pH. Mycoplasma penetrans gliding motility was not eliminated in the presence of a proton motive force inhibitor, a sodium motive force inhibitor, or an agent that depletes cellular ATP. At near-neutral pH, gliding speed increased as temperature increased. The absence of a clear chemical energy source for gliding motility and a positive correlation between speed and temperature suggest that energy derived from heat provides the major source of power for the gliding motor of M. penetrans.",
Arsenic,1383881,"A cohort study of spontaneous abortion and stillbirth in semiconductor employees Abstract: The process of manufacturing semiconductors uses a large number of solvents, including glycol ethers, and metals such as arsenic. The purpose of this study was to determine if females who work in the fabrication process are at increased risk of spontaneous abortion and stillbirth. A cohort of 1,368 current female workers (95.7% of eligible and contacted) participated in on-site questionnaire data collection of pregnancy and occupational history. Maternal job title and job duty during gestation were used to assign pregnancies to exposure categories fabrication, nonfabrication but chemically exposed, or nonfabrication, no chemical exposure. The 189 fabrication exposure pregnancies had a spontaneous abortion rate of 12.2%. Logistic regression analysis produced an odds ratio estimate of 1.62 (95% confidence interval (CI) 0.77-3.39) for risk of spontaneous abortion with fabrication exposure, and 2.00 (95% CI 0.85-4.71) for nonfabrication but chemical exposure. When specific job activities were examined, pregnancies of ""production engineers"" exhibited a spontaneous abortion rate of 37.0% (p = 0.001). Of the nine stillbirths reported, four were of ""assemblers,"" which resulted in a stillbirth rate of 8.5% (p = 0.011) for that group.",
Arsenic,2347793,"Fixed-bed column performance of Mn-incorporated iron(III) oxide nanoparticle agglomerates on As(III) removal from the spiked groundwater in lab bench scale Abstract: Assessment of the breakthrough performance of agglomerated Mn-incorporated Fe(III) oxide nanoparticle (MNFO) packed fixed-bed column on As(III) removal was conducted from the spiked groundwater. Variable parameters examined were column bed depth, effluent discharge rate and input As(III) concentration. Modeling of the breakthrough point (As concentration &lt;= 0.01 mg L-1) data by the Thomas and the Adams-Bohert models showed better fit of data with Thomas model (R-2 = 0.98-0.99) than Adams-Bohert model (R-2 = 0.90-0.94). The Bed Depth Service Time (BDST) modeling of breakthrough data at variable bed depths showed the length of mass transfer zone (Do), the adsorption capacity per unit volume (N-BD) and the rate constant (k(BD)) values 9.65 x 10(-7) cm, 3.34 mg cm(-3) and 2.74 x 10(-3) L mg(-1) min(-1), respectively. Best fixed-bed column performance was noted (V-B= 16.39L) only for the highest EBCT (8.3 min) and lowest input As(III) concentration (1.0 mg L-1). Thus, the MNFO fixed bed filtering column is capable to reduce not only high arsenic level but also other inorganic contaminants such as iron and phosphate from the groundwater. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,2279266,"Arsenite removal using a pilot system of ultrasound and ultraviolet followed by microfiltration Abstract: Batch and continuous-flow pilot tests using ultrasound (US), ultraviolet (UV) and a combination of US and UV were conducted to determine the oxidation rates of arsenite [As(III)]. Compared to the single processes of US or UV, the combined US/UV system was more effective for As(III) oxidation with a synergy index of more than 1.5. A high rate constant of As(III) removal was obtained as ferrous [Fe(II)] ions existed. Like the pseudo-Fenton reaction, Fe(II) species can participate in the production of additional ·OH by reacting with H2O2 produced by US, before being oxidized to Fe(III). From the results of batch tests, the optimum molar ratio of Fe(II)/As(III) and pH were found to be 83 and 6-9.5, respectively. Similarly, the continuous-flow pilot tests showed that US/UV system could remove As(III) below the regulation [10?gL(-1) as total As (Astot)] at 91 of molar ratio [Fe(II)/As(III)] and 3-h HRT. The continuous-stirred-tank-reactor (CSTR) modeling showed that the scavenging effect of anionic species (Cl(-) and CO3(2-)) for ·OH might prevail in the single processes, whereas it is insignificant in the combined process. Without using chemicals, microfiltration (MF) was adopted to treat sludge produced in oxidation step. In terms of an engineering aspect, the operational critical flux (CF) and cycle time were also optimized through the continuous-flow tests of MF system. As an energy-utilizing oxidation technique that does not require a catalyst, the combined energy system employing US/UV followed by MF could be a promising alternative for treating As(III) and Fe(II) simultaneously.",
Arsenic,1579295,"A cohort study on risk factors of lung cancer in yunnan tin miners Abstract: <strong>BACKGROUND: </strong>Smoking is a major cause of lung cancer. Studies of lung cancer among miners have shown that occupational exposure also played an important role. The aim of this study is to investigate radon, cigarette use and other risk factors of lung cancer in Yunnan tin miners and to provide a scientific basis for the prevention and control of occupational lung cancer.<br /><br /><strong>METHODS: </strong>A prospective cohort study was conducted among Yunnan tin miners, the associations between potential risk factors for lung cancer were analyzed by multivariate Cox regression model. Effects of age at first radon exposure and radon exposure rate on lung cancer risk were analyzed. The relationship between cumulative working level month and lung cancer was analyzed according to smoking status. The joint effect of tobacco use and cumulative radon exposure was analyzed based on additive and multiplicative models.<br /><br /><strong>RESULTS: </strong>Increased risk of lung cancer was associated with age at enrollment, tobacco use, prior bronchitis, and cumulative arsenic and radon exposure, while higher education level was associated with decreased lung cancer risk. An inverse effect of radon exposure rate was observed. There was no significant association between lung cancer risk and first radon exposure age. There was a significant additive interaction between tobacco use and radon exposure on lung cancer risk.<br /><br /><strong>CONCLUSIONS: </strong>Several risk factors may contribute to the high incidence of lung cancer in Yunnan tin miners. Further studies are warranted to evaluate joint effect of different risk factors.",
Arsenic,1677617,"Disruption of canonical TGF?-signaling in murine coronary progenitor cells by low level arsenic Abstract: Exposure to arsenic results in several types of cancers as well as heart disease. A major contributor to ischemic heart pathologies is coronary artery disease, however the influences by environmental arsenic in this disease process are not known. Similarly, the impact of toxicants on blood vessel formation and function during development has not been studied. During embryogenesis, the epicardium undergoes proliferation, migration, and differentiation into several cardiac cell types including smooth muscle cells which contribute to the coronary vessels. The TGF? family of ligands and receptors is essential for developmental cardiac epithelial to mesenchymal transition (EMT) and differentiation into coronary smooth muscle cells. In this in vitro study, 18hour exposure to 1.34?M arsenite disrupted developmental EMT programming in murine epicardial cells causing a deficit in cardiac mesenchyme. The expression of EMT genes including TGF?2, TGF? receptor-3, Snail, and Has-2 are decreased in a dose-dependent manner following exposure to arsenite. TGF?2 cell signaling is abrogated as detected by decreases in phosphorylated Smad2/3 when cells are exposed to 1.34?M arsenite. There is also loss of nuclear accumulation pSmad due to arsenite exposure. These observations coincide with a decrease in vimentin positive mesenchymal cells invading three-dimensional collagen gels. However, arsenite does not block TGF?2 mediated smooth muscle cell differentiation by epicardial cells. Overall these results show that arsenic exposure blocks developmental EMT gene programming in murine coronary progenitor cells by disrupting TGF?2 signals and Smad activation, and that smooth muscle cell differentiation is refractory to this arsenic toxicity.",
Arsenic,1033651,The content of arsenic in the hair in a case of acute lethal arsenic poisoning Abstract: ,
Arsenic,627080,"Development of a human physiologically based pharmacokinetic (PBPK) model for inorganic arsenic and its mono- and di-methylated metabolites Abstract: A physiologically-based pharmacokinetic (PBPK) model was developed to estimate levels of arsenic and its metabolites in human tissues and urine after oral exposure to arsenate (As(V)), arsenite (As(III)) or organoarsenical pesticides. The model consists of interconnected individual PBPK models for inorganic arsenic (As(V) and As(III)), monomethylarsenic acid (MMA(V)), and, dimethylarsenic acid (DMA(V)). Reduction of MMA(V) and DMA(V) to their respective trivalent forms also occurs in the lung, liver, and kidney including excretion in urine. Each submodel was constructed using flow limited compartments describing the mass balance of the chemicals in GI tract (lumen and tissue), lung, liver, kidney, muscle, skin, heart, and brain. The choice of tissues was based on physiochemical properties of the arsenicals (solubility), exposure routes, target tissues, and sites for metabolism. Metabolism of inorganic arsenic in liver was described as a series of reduction and oxidative methylation steps incorporating the inhibitory influence of metabolites on methylation. The inhibitory effects of As(III) on the methylation of MMA(III) to DMA, and MMA(III) on the methylation of As(III) to MMA were modeled as noncompetitive. To avoid the uncertainty inherent in estimation of many parameters from limited human data, a priori independent parameter estimates were derived using data from diverse experimental systems with priority given to data derived using human cells and tissues. This allowed the limited data for human excretion of arsenicals in urine to be used to estimate only parameters that were most sensitive to this type of data. Recently published urinary excretion data, not previously used in model development, are also used to evaluate model predictions.",
Arsenic,1597286,"Sources and spatial distribution of heavy metals in scleractinian coral tissues and sediments from the Bocas del Toro Archipelago, Panama Abstract: Marine ecosystems worldwide are threatened by aquatic pollution; however, there is a paucity in data from the Caribbean region. As such, five heavy metals (arsenic, cadmium, copper, zinc, mercury) were measured in tissues of the scleractinian corals Porites furcata and Agaricia tenuifolia and in adjacent sediments in the Bocas del Toro Archipelago, Panama. Samples were collected from five reef sites along a gradient of distance from an international shipping port and were analysed using inductively coupled plasma optical emission spectrometry and atomic absorption spectrophotometry for mercury. Copper and zinc were the most abundant metals and ranged from 11 to 63 mg kg(-1) and from 31 to 185 mg kg(-1) in coral tissues, respectively. The highest concentration of each metal was measured in P. furcata tissues, with copper and mercury concentrations significantly higher in P. furcata than in A. tenuifolia at every site. These results suggest that P. furcata has a higher affinity for metal accumulation and storage than A. tenuifolia. With the exception of cadmium, metal concentrations in coral tissues were generally elevated at coral reefs in closer proximity to the port; however, this pattern was not observed in sediments. Hard coral cover was lowest at reefs in closest proximity to the port, suggesting that metal pollution from port-related activities is influencing hard coral abundance at nearby coral reefs.",
Arsenic,2278029,"Metal exposure in schoolchildren and working children. A urinary biomonitoring study from Lahore, Pakistan Abstract: In order to document the exposure to trace metals among urban schoolchildren and rural working children, we measured the urinary concentrations of metals in schoolchildren from two areas of differing traffic intensity in Lahore, and in children working in carpet weaving or the brick industry outside Lahore. In a cross-sectional design, we recruited a convenience sample of 339 children aged 8-12 years (mean age 9.9 y, SD 1.4; 47% girls) from two elementary schools in Lahore - one situated in a high air pollution area (n=100) and one situated in an area with lower air pollution (n=79) - and from the carpet weaving industry (n=80) and brick industry (n=80). A spot urine sample was collected and concentrations of 20 metals and metalloids were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Samples of drinking water were similarly analyzed. In general, the urinary concentrations of several toxic metals (including Cr, Mn, As, Mo, Cd, Pb, U) were higher than international reference values. Concentrations of As were especially elevated in children working in the brick making industry [geometric mean (GM) 118?g/L], but they were also high among urban schoolchildren (GM 68?g/L and 56?g/L). Lead (Pb) was higher in urine from schoolchildren in the high air pollution area (GM 11?g/L) than in those from the lower pollution area (GM 5.3?g/L). Uranium (U) was high in both carpet weavers (GM 0.28?g/L) and brick kiln workers (GM 0.45?g/L). Concentrations of As, Pb, and U in drinking water corresponded well with urinary concentrations of metals. This descriptive study provides evidence for a high exposure to several toxic metals in this area of Pakistan. The concentrations of urinary As are in the order of those found in other regions of the world with high environmental exposure to As. The sources and pathways of exposure and the health significance of these findings need to be further investigated.",
Arsenic,2337225,"Comparison of scoring systems and outcome of patients admitted to a liver intensive care unit of a tertiary referral centre with severe variceal bleeding Abstract: <strong>BACKGROUND: </strong>Acute variceal haemorrhage (AVH) is associated with significant mortality.<br /><br /><strong>AIMS: </strong>To determine outcome and factors associated with hospital mortality (HM) in patients with AVH admitted to intensive care unit (ICU) and to compare outcomes of patients requiring transfer to a tertiary ICU (transfer group, TG) to a local in-patient group (LG).<br /><br /><strong>METHODS: </strong>A retrospective study of all adult patients (N = 177) admitted to ICU with AVH from 2000-2008 was performed.<br /><br /><strong>RESULTS: </strong>Median age was 48 years (16-80). Male represented 58%. Median MELD score was 16 (6-39), SOFA score was 8 (6-11). HM was higher in patients who had severe liver disease or critical illness measured by MELD, SOFA, APACHE II scores and number of failed organs (NFO), P &lt; 0.05. Patients with day-1 lactate ? 2 mmol/L had increased HM (P &lt; 0.001). MELD score performed as well as APACHE II, SOFA and NFO (P &lt; 0.001) in predicting HM (AUROC = 0.84, 0.81, 0.79 and 0.82, respectively P &gt; 0.05 for pair wise comparisons). Re-bleeding was associated with increased HM (56.9% vs. 31.6%, P = 0.002). The TG (n = 124) had less severe liver disease and critical illness and consequently had lower HM than local patients (32% vs. 57%, P = 0.002). TG patients with ?2 endoscopies prior to transfer had increased 6-week mortality (P = 0.03). Time from bleeding to transfer ?3 days was associated with re-bleeding (OR = 2.290, P = 0.043).<br /><br /><strong>CONCLUSIONS: </strong>MELD score was comparable to ICU prognostic models in predicting mortality. Blood lactate was also predictive of hospital mortality. Delays in referrals and repeated endoscopy were associated with increased re-bleeding and mortality in this group.",
Arsenic,2064261,"Hair trace elementary profiles in aging rodents and primates: Links to altered cell homeodynamics and disease Abstract: Aging is associated with an increased incidence of pathological conditions such as neurodegeneration, cardiovascular and renal disease, and cancer. These conditions are believed to be linked to a disruption in cell homeodynamics, which is regulated by essential trace elements. In this study we used hair elementary analysis by inductively coupled plasma mass spectrometry (ICPMS) to examine age-related profiles of 47 elements in both rats and common marmoset monkeys. Hair was collected from young adult (6 months) and aged (18 months) Long-Evans male rats, and young adult (2 years), middle-aged (4 years) and aged (>8 years) marmosets. The results revealed that aging reduces content levels of cobalt, potassium and selenium while content levels of aluminium, arsenic, boron, mercury, molybdenum, and titanium were elevated in aged rats. Similarly, aged marmosets showed reduced levels of cobalt and elevated levels of aluminium. Case studies in aged rats revealed that myocardial infarction was associated with elevated levels of sodium, potassium and cadmium and reduced zinc, while renal failure was linked to elevated content of potassium, chloride and boron and reduced contents of manganese. Carcinoma was linked to elevated arsenic and reduced selenium levels. These findings indicate that hair elementary profiles in healthy aging and age-related diseases reflect altered cell and organ metabolic functions. Cobalt and aluminium in particular may serve as biomarkers of aging in animal models. Thus, elementary deposition in hair may have predictive and diagnostic value in age-related pathological conditions, including cardiovascular and kidney disease and cancer.",
Arsenic,1340238,"ZIP8 expression in human proximal tubule cells, human urothelial cells transformed by Cd+2 and As+3 and in specimens of normal human urothelium and urothelial cancer Abstract: <strong>BACKGROUND: </strong>ZIP8 functions endogenously as a Zn+2/HCO3- symporter that can also bring cadmium (Cd+2) into the cell. It has also been proposed that ZIP8 participates in Cd-induced testicular necrosis and renal disease. In this study real-time PCR, western analysis, immunostaining and fluorescent localization were used to define the expression of ZIP8 in human kidney, cultured human proximal tubule (HPT) cells, normal and malignant human urothelium and Cd+2 and arsenite (As+3) transformed urothelial cells.<br /><br /><strong>RESULTS: </strong>It was shown that in the renal system both the non-glycosylated and glycosylated form of ZIP8 was expressed in the proximal tubule cells with localization of ZIP8 to the cytoplasm and cell membrane; findings in line with previous studies on ZIP8. The studies in the bladder were the first to show that ZIP8 was expressed in normal urothelium and that ZIP8 could be localized to the paranuclear region. Studies in the UROtsa cell line confirmed a paranuclear localization of ZIP8, however addition of growth medium to the cells increased the expression of the protein in the UROtsa cells. In archival human samples of the normal urothelium, the expression of ZIP8 was variable in intensity whereas in urothelial cancers ZIP8 was expressed in 13 of 14 samples, with one high grade invasive urothelial cancer showing no expression. The expression of ZIP8 was similar in the Cd+2 and As+3 transformed UROtsa cell lines and their tumor transplants.<br /><br /><strong>CONCLUSION: </strong>This is the first study which shows that ZIP8 is expressed in the normal urothelium and in bladder cancer. In addition the normal UROtsa cell line and its transformed counterparts show similar expression of ZIP8 compared to the normal urothelium and the urothelial cancers suggesting that the UROtsa cell line could serve as a model system to study the expression of ZIP8 in bladder disease.",
Arsenic,1677530,"Treating chronic arsenic toxicity with high selenium lentil diets Abstract: Arsenic (As) toxicity causes serious health problems in humans, especially in the Indo-gangetic plains and mountainous areas of China. Selenium (Se), an essential micronutrient is a potential mitigator of As toxicity due to its antioxidant and antagonistic properties. Selenium is seriously deficient in soils world-wide but is present at high, yet non-toxic levels in the great plains of North America. We evaluate the potential of dietary Se in counteracting chronic As toxicity in rats through serum biochemistry, blood glutathione levels, immunotoxicity (antibody response), liver peroxidative stress, thyroid response and As levels in tissues and excreta. To achieve this, we compare diets based on high-Se Saskatchewan (SK) lentils versus low-Se lentils from United States. Rats drank control (0ppm As) or As (40ppm As) water while consuming SK lentils (0.3ppm Se) or northwestern USA lentils (&lt;0.01ppm Se) diets for 14weeks. Rats on high Se diets had higher glutathione levels regardless of As exposure, recovered antibody responses in As-exposed group, higher fecal and urinary As excretion and lower renal As residues. Selenium deficiency caused greater hepatic peroxidative damage. Thyroid hormones, triiodothyronine (T3) and thyroxine (T4), were not different. After 14weeks of As exposure, health indicators in rats improved in response to the high Se lentil diets. Our results indicate that high Se lentils have a potential to mitigate As toxicity in laboratory mammals, which we hope will translate into benefits for As exposed humans.",
Arsenic,2343550,"Species-specific content of As, Pb, and other elements in pangas (Pangasianodon hypophthalmus) and tilapia (Oreochromis niloticus) from aquaculture ponds in southern Bangladesh Abstract: Content of arsenic and lead and 10 other potentially toxic elements (Ba, Ce, Cr, Cu, Fe, Mg, Mn, Se, Sr and Zn) was determined in tilapia and pangas from aquaculture ponds in southern Bangladesh. Tilapia had 1.6- to 4.3-fold higher content of Mn, As, Sr, and Ba than pangas, possibly caused by different feeding habits of the two fish. The other elements had similar concentrations in both species. Content of As in tilapia and pangas was 0.37 and 0.11 mu g g(-1), respectively, while Pb made up 0.056 and 0.051 mu g g(-1), respectively. Water treatment during the farming period (sand filtration and probiotic bacteria) and final depuration in groundwater for up to 48 h had no effect on content of the elements. For As, consumption of 100 g fresh fish per day contained 1.3% (pangas) and 5% (tilapia) of the maximum tolerable daily intake according to FAO recommendations. Relative to whole tilapia from a lake near Dhaka (Begum et al., 2005), muscle tissue in tilapia from the ponds had 3-50 x lower content for Zn, Cu, Mn and Pb, while the remaining elements were similar. Thus, our results suggest that pond-raised fish in Bangladesh may be a healthier choice than wild fish, especially if the fish originate from freshwater receiving untreated wastewater. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,2347602,"Co-regulated genes link sulfide:quinone oxidoreductase and arsenic metabolism in Synechocystis sp. PCC6803 Abstract: Although the biogeochemistry of the two environmentally hazardous compounds arsenic and sulfide has been extensively investigated, the biological interference of these two toxic, but potentially energy-rich compounds has only been hypothesized and indirectly proven. Here we provide direct evidence for the first time that in the photosynthetic model organism Synechocystis sp. PCC6803 the two metabolic pathways are linked by co-regulated genes that are involved in arsenic transport and sulfide oxidation, and probably in sulfide based alternative photosynthesis. Although Synechocystis sp. PCC6803 is an obligate photoautotrophic cyanobacterium that grows via oxygenic photosynthesis we discovered that specific genes are activated in the presence of sulfide or arsenite to exploit the energy potentials of these chemicals. These genes form an operon that we termed suoRSCT, located on a transposable element of type IS4 on the plasmid pSYSM of the cyanobacterium. SuoS (sll5036) encodes a light dependent, type I sulfide:quinone oxidoreductase. The suoR (sll5035) gene downstream of suoS encodes a regulatory protein that belongs to the ArsR-type repressors that are normally involved in arsenic resistance. We found that this repressor has dual specificity, resulting in 200 fold induction of the operon upon either arsenite or sulfide exposure. The suoT gene encodes a transmembrane protein similar to chromate transporters but in fact functioning as arsenite importer at permissive concentrations. We propose that the proteins encoded in the suoRSCT operon might have played an important role under anaerobic, reducing conditions on primordial Earth and it was acquired by the cyanobacterium via horizontal gene transfer.",
Arsenic,2088502,"A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: Implications in measuring biological effects of arsenic compounds Abstract: <strong>INTRODUCTION: </strong>Glutathione, a major cellular non-protein thiol (NPSH), serves a central role in repairing damage induced by cancer drugs, pollutants and radiation and in the detoxification of several cancer chemotherapeutic drugs and toxins. Current methods measure glutathione levels only, which require cellular extraction, rather than the glutathione recycling dependent antioxidant activity in intact cells. Here, we present a novel method using a bioactive probe of the oxidative pentose phosphate cycle, termed the OxPhos(TM) test, to quantify glutathione recycling dependent antioxidant activity in whole blood and intact human and rodent cells without the need for the isolation and cytoplasm extraction of cells.<br /><br /><strong>METHODS: </strong>OxPhos(TM) test kit (Rockland Immunochemicals, USA), which uses hydroxyethyldisulfide (HEDS) as a probe for the oxidative pentose phosphate cycle, was used in these studies. The results with OxPhos(TM) test kit in human blood and intact cells were compared with total thiol and high pressure liquid chromatography/electrochemical detection of HEDS metabolism.<br /><br /><strong>RESULTS: </strong>The OxPhos(TM) test measured glutathione-dependent antioxidant activity both in intact human and rodent cells and breast cancer patient's blood with a better correlation coefficient and biological variability than the thiol assay. Additionally, human blood and mammalian cells treated with various arsenicals showed a concentration-dependent decrease in activity.<br /><br /><strong>DISCUSSION: </strong>The results demonstrate the application of this test for measuring the antioxidant capacity of blood and the effects of environmental pollutants/toxins. It opens up new avenues for an easy and reliable assessment of glutathione-dependent antioxidant capacity in various diseases such as stroke, blood borne diseases, infection, cardiovascular disease and other oxidative stress related diseases and as a prognostic indicator of chemotherapy response and toxicity. The use of this approach in pharmacology/toxicology including screening drugs that improve the glutathione-dependent antioxidant capacity and not just the glutathione level is clinically relevant since mammalian cells require glutathione dependent pathways for antioxidant activity.",
Arsenic,1350522,Increased bladder cell micronuclei in two populations environmentally exposed to arsenic in drinking water Abstract: ,
Arsenic,2337072,"Elemental characterization of plants and soils in Panasqueira tungsten mining region Abstract: Mining activities represent a current source of pollution due to the large release of trace elements from mineral particles into the soil, atmosphere, and ecosystems. In active or abandoned metal-mining areas, direct discharge from mining deposits is one of the most common processes of contamination. <br> <br>In this work, we calculated the elemental concentrations of plants, edible for cattle, which might contain high values of toxic elements, such as As, Cu, Zn, and W, originated from mining exploitation, especially wolframite. Several species of plants originating from the same contaminated place, close to the mine, were the subject of our study in order to compare the uptake of harmful elements, from the contaminated soils, in the different plants. We have used the energy-dispersive X-ray fluorescence technique to perform the analysis and quantification of the elements present in the collected samples. The quantification was based on the fundamental parameters method for plants and on the WinAxil compare mode using a standard reference material, for soils. Calibration against a series of standard samples has been carried out. <br> <br>A comparison between contaminated and control samples, within the same species, was performed. The contamination of the two mining wash sites is assessed by comparing the elemental concentration of several plants in these places. Elemental content in soils was investigated, and a comparison between elemental levels in plants was performed. <br> <br>High concentrations of tungsten were found near the new wash site. Arsenic was found throughout the area in concentrations many times higher than those recommended by the World Health Organization.",
Arsenic,8409,"Respiratory cancer among copper smelter workers: Recent mortality statistics Abstract: A survey of mortality among copper smelter workers in the western United States revealed that a respiratory cancer excess previously observed during the period 1938 through 1963 continued from 1964 through 1977. When analyzed in relation to smelter employment prior to 1964, the recent increase in respiratory cancer was linked to work in plant areas where airborne arsenic concentrations were elevated and to a cumulative arsenic exposure index, although some excess risk was also associated with long-term employment in jobs with limited exposures to arsenic. The arsenic-related excess remained after adjustment for work in areas of the plant with elevated concentrations of sulphur dioxide, which was not found to have an independent influence upon cancer risk. Increased rates for nonmalignant respiratory disease were also observed, but were not significantly associated with arsenic exposure.",
Arsenic,1016623,"Modulation of DNA repair processes by arsenic and selenium compounds Abstract: Nickel, cadmium, cobalt and arsenic compounds are well known carcinogens to humans and experimental animals. In addition to the induction of mainly oxidative DNA damage, they interfere with nucleotide and base excision repair (BER) at low, non-cytotoxic concentrations. In case of arsenic, an inactivation of DNA repair has also been observed for the trivalent and pentavalent methylated metabolites, with the strongest effects exerted by MMA(III) and DMA(III). As potential molecular targets, interactions with so-called zinc finger proteins involved in DNA repair and/or DNA damage signaling have been identified. For example, arsenite suppresses poly(ADP-ribosyl)ation at extremely low, environmentally relevant concentrations. Also, Fpg and XPA involved in BER and NER, respectively, are inactivated by arsenite, MMA(III) and DMA(III). Nevertheless, an interaction with the zinc finger structures of DNA repair proteins may also occur by essential trace elements such as certain selenium compounds, which appear to exert anticarcinogenic properties at low concentrations but may compromise genetic stability at higher concentrations.",
Arsenic,1337914,"Comparing the joint effect of arsenic exposure, cigarette smoking and risk genotypes of vascular endothelial growth factor on upper urinary tract urothelial carcinoma and bladder cancer Abstract: Arsenic exposure and cigarette smoking are environmental risk factors for urothelial carcinoma (UC). Vascular endothelial growth factor (VEGF) is the key regulator of angiogenesis in various malignancies. This study investigates the joint effect of arsenic exposure, cigarette smoking, and VEGF polymorphisms on UC risk. This was a hospital-based case-control study consisting of 730 histopathologically confirmed UC cases, including 470 bladder cancers, 260 upper urinary tract UCs (UUTUCs), and 850 age-matched controls, recruited from September 1998 to December 2009. UC risk was estimated by odds ratios and 95% confidence intervals using unconditional logistic regression. Ever smokers with high arsenic exposure had significantly increased risks of 5.7 and 6.4 for bladder cancer and UUTUC, respectively. Moreover, ever smokers with high arsenic exposure carrying 1 or 2 risk genotypes of the VEGF gene had a significantly increased risk of 6.6 for bladder cancer and a strikingly higher risk of 9.9 for UUTUC. Additionally, UUTUC cases with high arsenic exposure carrying 1 or 2 risk genotypes of the VEGF gene had a non-significant increased risk of advanced tumor stage. Our findings suggest that arsenic exposure, cigarette smoking, and risk genotypes of VEGF contribute to a higher risk of UUTUC than of bladder cancer.",
Arsenic,1016114,"Cancer excess after arsenic exposure from contaminated milk powder Abstract: <strong>OBJECTIVES: </strong>Long-term exposure to inorganic arsenic is related to increased risk of cancer in the lung, skin, bladder, and, possibly, other sites. However, little is known about the consequences of developmental exposures in regard to cancer risk. During early summer in 1955, mass arsenic poisoning of infants occurred in the western part of Japan because of contaminated milk powder. Okayama Prefecture was most severely affected. We examined whether the affected birth cohorts in this prefecture experienced increased cancer mortality.<br /><br /><strong>METHODS: </strong>We targeted subjects who were born from September 1950 to August 1960 and died in Okayama Prefecture between January 1969 and March 2008 due to malignant neoplasm (N = 3,141). We then compared cancer mortality (total, liver, pancreatic, lung, bladder/kidney, and hematopoietic cancers) between cohorts born before the milk poisoning (exposed group) and cohorts born after the poisoning (nonexposed group). We estimated mortality ratios and 95% confidence intervals.<br /><br /><strong>RESULTS: </strong>Total and liver cancers were elevated in the cohort up to 1 year of age at time of the poisoning. In addition, pancreatic and hematopoietic cancers were elevated in the cohorts up to 5 years of age, and mortality ratios were approximately twice those of the nonexposed group. Increased risk of lung and bladder/kidney cancers was not apparent.<br /><br /><strong>CONCLUSIONS: </strong>Although dilution is present in these cohort-based data, our study highlights the notion that developmental arsenic exposure may lead to a different pattern of cancer, including increases in pancreatic and hematopoietic cancer, as compared with adult or lifetime exposures to inorganic arsenic.",
Arsenic,1338774,"Approaches to increase arsenic awareness in Bangladesh: An evaluation of an arsenic education program Abstract: The objective of this study was to design and evaluate a household-level arsenic education and well water arsenic testing intervention to increase arsenic awareness in Bangladesh. The authors randomly selected 1,000 study respondents located in 20 villages in Singair, Bangladesh. The main outcome was the change in knowledge of arsenic from baseline to follow-up 4 to 6 months after the household received the intervention. This was assessed through a pre- and postintervention quiz concerning knowledge of arsenic. Respondents were between 18 and 102 years of age, with an average age of 37 years; 99.9% were female. The knowledge of arsenic quiz scores for study participants were significantly higher at follow-up compared with baseline. The intervention was effective in increasing awareness of the safe uses of arsenic-contaminated water and dispelling the misconception that boiling water removes arsenic. At follow-up, nearly all respondents were able to correctly identify the meaning of a red (contaminated) and green (arsenic safe) well relative to arsenic (99%). The educational program also significantly increased the proportion of respondents who were able to correctly identify the health implications of arsenic exposure. However, the intervention was not effective in dispelling the misconceptions in the population that arsenicosis is contagious and that illnesses such as cholera, diarrhea, and vomiting could be caused by arsenic. Further research is needed to develop effective communication strategies to dispel these misconceptions. This study demonstrates that a household-level arsenic educational program can be used to significantly increase arsenic awareness in Bangladesh.",
Arsenic,2345815,"Geochemical characterization of groundwater from an arid region in India Abstract: A study on the geochemical processes in arid region of western India (Kachchh district) was carried out using major, minor, trace metal data and isotopic composition (delta H-2, delta O-18) of groundwaters. Results indicate that the distribution of chemical species in groundwater of this district is controlled by leaching of marine sediments, dissolution of salts in root zone and incongruent dissolution of carbonate minerals. Common inorganic contaminants such as fluoride, nitrate and phosphate are within drinking water permissible limits. However, most of the samples analyzed contain total dissolved salts more than desirable limits and fall in doubtful to unsuitable category with regard to irrigational purpose. Trace metal data indicates no contamination from toxic elements such as arsenic and lead. An increased salt content is observed in groundwater at shallower depths indicating mixing with surface water sources. The chemical characteristics of the groundwater have found to be strongly dependent on the local lithological composition. Environmental isotopic data indicates that the groundwater is of meteoric origin and has undergone limited modification before its recharge. The processes responsible for observed brackishness are identified using chemical and isotope indicators, which are in agreement with subsurface lithology and hydrochemistry. These data though represent hydrochemical scenario of 2001 can still be used for understanding the long-term fluctuations in water chemistry and would be quite useful for the planners in validating groundwater quality models.",
Arsenic,1019958,"British anti-Lewisite (dimercaprol): an amazing history Abstract: Emergency physicians are familiar with British anti-Lewisite (BAL) because it is a heavy metal-chelating agent that is recommended in some cases of metal poisoning, especially arsenic. Although there are more modern chelating agents, the fact that BAL is still recommended and stocked by hospital pharmacies more than 60 years after its initial synthesis is itself remarkable. During World War II, BAL minimized the risk to the Allied infantry of injury or death from Lewisite, a very potent arsenic-based chemical warfare agent. Once developed, BAL revolutionized the treatment of heavy metal poisonings, both accidental and iatrogenic (eg, toxicity from treatment of arthritis with gold salts). In 1951, BAL was used to treat Wilson's disease with striking success. Today, BAL might again become prominent should terrorists or governments use Lewisite against civilians or military forces.",
Arsenic,2343514,"The nasal cycle during wakefulness and sleep and its relation to body position Abstract: <strong>OBJECTIVES/HYPOTHESIS: </strong>To compare the occurrence, duration, and relative amplitudes of the nasal cycle (NC) during wakefulness and sleep, and to investigate the relationship of the NC to body position.<br /><br /><strong>STUDY DESIGN/METHODS: </strong>In 20 healthy subjects, the NC was measured by long-term rhinoflowmetry for an average 23.1 hours during wakefulness and sleep. Head and body position were also recorded during the night.<br /><br /><strong>RESULTS: </strong>A classic NC was displayed by 50% of subjects during wakefulness and by 75% of the subjects during sleep. Cycle duration during wakefulness was 91.1 minutes (± 65.2; 20-337), increasing significantly during sleep to 178 minutes (± 92.8; 21-498) (P?&lt;?0.01). The relative mean flow of the working phase during wakefulness was 67.6% (± 8.0; 58-90), and it was significantly higher during sleep at 82.0% (± 6.8; 63-93) (P?&lt;?0.01). On recumbency, there was a significant correlation between body position and resting phase side (r?=?0.67; P?=?0.024). To a significant extent, positional shifts led to subsequent NC laterality changes (22%; P &lt; 0.01). Conversely, to a significant extent, positional shifts preceded NC laterality changes (57.6%; P?&lt;?0.01). Body position changed in a nonsignificant number of cases (30.3%; P?=?0.16) due to reversal of the congestion side of the inferior turbinates.<br /><br /><strong>CONCLUSION: </strong>The results of our study show that the NC during sleep is characterized by longer cycle durations and greater amplitudes than during wakefulness on normal physical activity. Shifts in body position during sleep alter the NC in a specific direction to a significant extent, but the opposite is not the case.<br /><br /><strong>LEVEL OF EVIDENCE: </strong>4. Laryngoscope, 124:1492-1497, 2014.",
Arsenic,1070345,"Heavy metal contaminants in Yerberia shop products Abstract: Complementary and alternative medications, including the use of herbal medications, have become quite popular in the USA. Yerberias are found throughout the southwest and specialize in selling Hispanic herbal products. The products sold in these stores are not regulated by any governmental agency. Previous reports have found Ayurvedic medications contain high levels of lead, mercury, and arsenic. The primary purpose of this study is to examine the prevalence of heavy metal contaminants sold at Yerberia stores in the southwest. Yerberias in the Phoenix, Arizona area were identified via search of an on-line search engine using the words &quot;Yerberia Phoenix.&quot; Every second store was selected, and products were purchased using a standard script. The products were subsequently analyzed for mercury, lead, and arsenic. The main outcome is the prevalence of heavy metal content in over-the-counter &quot;cold&quot; medications purchased at a Yerberia. Twenty-two samples were purchased. One product contained pure camphor (2-camphone) and was subsequently not further analyzed. Of the 21 samples analyzed, lead was found in 4/21 (19.4 %). Arsenic and mercury were in 1/21 (4.8 %) each. Because two samples contained two heavy metals, the total prevalence of heavy metals was 4/21 (19.4). Heavy metal contaminants are commonly encountered in over-the-counter herbal &quot;cold&quot; medications purchased at Yerberias in the southwest.",
Arsenic,1024660,"Arsenic in various foods: cumulative data Abstract: Data for the arsenic content in various foods were collated. The number of collected values was about 2500 columns, which enables an estimation of the range of arsenic contents in each food group. Data were categorized into six groups (crops, milk/meat/egg, fish, algae, seafood, others) and expressed as a percentile graph. In addition, the inorganic arsenic ratio of each food group was estimated. This approach enabled the authors to understand the arsenic contents of some food groups at a glance. The intake of inorganic arsenic seems to be mostly from seafood. The contribution from other categories of food is small.",
Arsenic,2298722,"Arsenic-containing fatty acids and hydrocarbons in marine oils - determination using reversed-phase HPLC-ICP-MS and HPLC-qTOF-MS Abstract: Arsenolipids are the major arsenic species present in marine oils. Several structures of arsenolipids have been elucidated the last 5 years, demonstrating the chemical complexity of this trace element in the marine environment. Several commercial fish oils and marine oils, ranging in total arsenic concentrations from 1.6 to 12.5mgkg(-1) oil, were analyzed for arsenolipids using reversed-phase high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The arsenolipids were quantified using three different arsenic-containing calibration standards; dimethylarsinate (DMA), triphenylarsinoxide (Ph3AsO) and a synthesized arsenic-containing hydrocarbon (AsHC) (dimethylarsinoyl nonadecane; C21H43AsO). The observed variation in signal intensity for arsenic during the gradient elution profile in reversed-phase HPLC was compensated for by determining the time-resolved response factors for the arsenolipids. Isotopes of germanium ((74)Ge) and indium ((115)In) were suited as internal standards for arsenic, and were used for verification of the arsenic signal response factors during the gradient elution. Dimethylarsinate was the most suitable calibration standard for the quantification of arsenolipids, with recoveries between 91% and 104% compared to total arsenic measurements in the same extracts. A range of marine oils was investigated, including oils of several fish species, cod liver and seal, as well as three commercial fish oils. The AsHCs - C17H38AsO, C19H42AsO and C23H38AsO - were identified as the major arsenolipids in the extracts of all oils by HPLC coupled with quadrupole time-of-flight mass spectrometry (qTOF-MS). Minor amounts of two arsenic-containing fatty acids (AsFAs) (C23H38AsO3 and C24H38AsO3) were also detected in the oils. The sum of the AsHCs and the AsFAs determined in the present study accounted for 17-42% of the total arsenic in the oils.",
Arsenic,681658,"Chemical carcinogens and overnutrition in diet-related cancer Abstract: The intake of known dietary carcinogens was compiled and the cancer risk was estimated on the basis of carcinogenic potencies in animals as derived from the Carcinogenic Potency Database by Gold and co-workers. The total cancer risk was compared with the number of cancer cases attributed by epidemiologists to dietary factors (one-third of all cancer cases, i.e. approximately 80,000 per one million lives). Except for alcohol, the known dietary carcinogens could not account for more than a few hundred cancer cases. This was seen both with the DNA-reactive carcinogens (heterocyclic aromatic amines, polycyclic aromatic hydrocarbons, N-nitroso compounds, estragole, aflatoxin B1, ethyl carbamate, to name the most important factors) as well as with those carcinogens which have not been shown to react with DNA (e.g. caffeic acid and the carcinogenic metals arsenic and cadmium). Residues and contaminants turned out to be negligible. Among the various possibilities to explain the discrepancy we investigated the role of overnutrition. Dietary restriction in animals is well known for its strong reducing effect on spontaneous tumor formation. These data can be used to derive a carcinogenic potency for excess macronutrients: the tumor incidence seen with the restricted animals is taken as a control value and the increased tumor incidence in the animals fed ad libitum is attributed to the additional feed intake. For excess standard diet in rats, a carcinogenic potency TD50 of 16 g/kg/day was deduced from a recent study. Overnutrition in Switzerland, estimated to be 5.5 kcal/kg/day, was converted to excess food (1.9 g/kg/day) and the cancer incidence was calculated. The result, 60,000 cancer cases per one million lives, is provocatively close to the number of cases not explained by the known dietary chemical carcinogens. Mechanistic studies will be required to test our hypothesis and investigate the role of different types of macronutrients in overnutrition.",
Arsenic,1022130,"Rice consumption contributes to arsenic exposure in US women Abstract: Emerging data indicate that rice consumption may lead to potentially harmful arsenic exposure. However, few human data are available, and virtually none exist for vulnerable periods such as pregnancy. Here we document a positive association between rice consumption and urinary arsenic excretion, a biomarker of recent arsenic exposure, in 229 pregnant women. At a 6-mo prenatal visit, we collected a urine sample and 3-d dietary record for water, fish/seafood, and rice. We also tested women's home tap water for arsenic, which we combined with tap water consumption to estimate arsenic exposure through water. Women who reported rice intake (n = 73) consumed a median of 28.3 g/d, which is ?0.5 cup of cooked rice each day. In general linear models adjusted for age and urinary dilution, both rice consumption (g, dry mass/d) and arsenic exposure through water (?g/d) were significantly associated with natural log-transformed total urinary arsenic (?rice = 0.009, ?water = 0.028, both P &lt; 0.0001), as well as inorganic arsenic, monomethylarsonic acid, and dimethylarsinic acid (each P &lt; 0.005). Based on total arsenic, consumption of 0.56 cup/d of cooked rice was comparable to drinking 1 L/d of 10 ?g As/L water, the current US maximum contaminant limit. US rice consumption varies, averaging ?0.5 cup/d, with Asian Americans consuming an average of &gt;2 cups/d. Rice arsenic content and speciation also vary, with some strains predominated by dimethylarsinic acid, particularly those grown in the United States. Our findings along with others indicate that rice consumption should be considered when designing arsenic reduction strategies in the United States.",
Arsenic,1349539,"Arsenic, an old case - The chronic heavy-metal poisoning of Peale, Raphaelle (1774-1825) Abstract: ",
Arsenic,1350500,"Modeling of the Removal of Arsenic Species from Simulated Groundwater Containing As, Fe, and Mn: A Neural Network Based Approach Abstract: ",
Arsenic,1346613,Functional characterization of the zebrafish gadd45 alpha b gene promoter and its application as a biosensor Abstract: ,
Arsenic,1508623,"In vitro toxicological characterisation of the S-containing arsenic metabolites thio-dimethylarsinic acid and dimethylarsinic glutathione Abstract: Inorganic arsenic is a well-documented, exposure relevant human carcinogen. A promising starting point to further understand the mechanisms behind inorganic arsenic carcinogenicity might be a formation of reactive, highly toxic metabolites during human arsenic metabolism. This study characterises the toxicity of recently identified S-containing arsenic metabolites in cultured human A549 lung adenocarcinoma epithelium cells. In direct comparison to arsenite, thio-dimethylarsinic acid (thio-DMA) and dimethylarsinic glutathione (DMAG) exerted a 5- to 20-fold stronger cytotoxicity and showed a 2- to 20-fold higher cellular bioavailability, respectively. All three arsenicals disturbed cell cycle progression at cytotoxic concentrations, but failed to increase the level of reactive oxygen and nitrogen species (RONS) in healthy A549 cells. However, a strong disturbance of the oxidative defense system was observed after incubation with absolutely sub-cytotoxic, pico- to nanomolar concentrations of arsenite and thio-DMA, respectively. Thus, both GSH and GSSG levels were significantly decreased by up to 40%. Accordingly, RONS levels of oxidatively (HO) stressed cells were strongly increased by the arsenicals. Since in vivo RONS are permanently endogenously and exogenously produced, this boost of the existing oxidative stress by arsenite and thio-DMA might contribute to the process of inorganic arsenic induced carcinogenicity.",
Arsenic,1353610,Overexpression of AtHsp90.3 in Arabidopsis thaliana impairs plant tolerance to heavy metal stress Abstract: ,
Arsenic,627908,"Induction of p53 protein expression by sodium arsenite Abstract: Arsenic is carcinogen for humans and has been shown to act as an enhancer in initiated animal models. In a previous work we found impairment of lymphocyte proliferation in arsenic-exposed individuals and in vitro we obtained dose-related inhibition of mitotic response and lymphocyte proliferation. Intrigued by these effects and based on the role of p53 on cell proliferation, we tested different concentrations of sodium arsenite for their ability to induce the expression of tumor suppressor gene p53 in different cell lines (HeLa, C-33A. Jurkat) and a lymphoblast cell line transformed with Epstein-Barr virus (LCL-EBV). We also evaluated changes in their viability after 24 h arsenic treatment; C-33A cells showed the higher sensitivity to arsenic treatment while HeLa, Jurkat and LCL-EBV cells showed similar cytotoxicity curves. Immunoblots showed an increased expression of p53 gene with 1 microM sodium arsenite in Jurkat cells and 10 microM sodium arsenite in HeLa and LCL-EBV cells. In addition, we transfected Jurkat cells and human lymphocytes with wild-type and mutated p53 genes; lymphocytes and Jurkat cells that received the mutated p53 showed increased sensitivity to arsenic cytotoxicity. Data obtained indicate that arsenic induces p53 expression and that cells with a functional p53 contend better with damage induced by this metalloid.",
Arsenic,1337479,"Operatively treated traumatic versus non-traumatic rotator cuff ruptures: A registry study Abstract: Backround. Operative treatment of traumatic rotator cuff ruptures, i.e. ruptures with a predisposing traumatic event, is reported to yield superior results compared to operative treatment of non-traumatic, degenerative ruptures. Aim. The purpose of this study was to evaluate the difference of outcome, peroperative findings, and demographics after operative treatment of traumatic versus non-traumatic rotator cuff rupture. Methods. A total of 306 consecutive shoulders with an operated rotator cuff rupture (124 traumatic and 182 non-traumatic) were followed up. Constant and Murley score, size of the rupture, and age of the patients were used as an outcome measure. Results. A total of 112 traumatic and 167 non-traumatic rotator cuff rupture shoulders were available for 1-year follow-up (91%). Mean Constant and Murley score was preoperatively lower in the traumatic group (46 versus 52, P = 0.01). At 3 months postoperatively, Constant and Murley scores were 61 and 60 (P = 0.72) and at 1 year 73 and 77 (P = 0.03), respectively. Altogether 91% of the patients in the traumatic and 93% in the non-traumatic group were satisfied with the final outcome (P = 0.45). In 94% of traumatic and 95% of a non-traumatic cases the rupture involved the supraspinatus tendon. In the traumatic group the rupture was larger and involved more frequently the whole supraspinatus insertion area (41% versus 17%, P &lt; 0.0001). Mean age of patients was 58 and 57 years, respectively. Conclusion. Operative treatment of both traumatic and non-traumatic rotator cuff ruptures gives essentially good results. In our cohort, patients' recollection of predisposing trauma reflects the size of the rotator cuff rupture, but does not reflect the age of the patients.",
Arsenic,2278465,"Characterization and evaluation of arsenic and boron adsorption onto natural geologic materials, and their application in the disposal of excavated altered rock Abstract: Construction of tunnels in Hokkaido, Japan often excavates rocks containing substantial amounts of arsenic (As) and boron (B). When these rocks are exposed to the environment, As and B are leached out that could potentially contaminate the surrounding soil and groundwater. Natural geologic materials contain minerals like Al-/Feoxyhydroxides/oxides that have As and B adsorption capabilities. Because these materials are widespread and readily available, they could be utilized in the mitigation of As and B leached out from these sources. This paper describes the ability of three natural geologic materials (i.e., pumiceous tuffs, partly-weathered volcanic ashes and coastal marine sediments) to sequester As and B from aqueous solutions and the actual leachate of a hydrothermally altered rock. The adsorption of As fitted well with either the Langmuir or Freundlich isotherm while that of B followed the Henry-type model (linear). Among the samples, those containing substantial amorphous Al and Fe exhibited higher As adsorption. However, the distribution coefficient of B only had a moderate positive correlation with these amorphous phases. The best adsorbent among these natural geologic materials was utilized in the adsorption layer of the column experiments. Adsorption of As was more effective the thicker the adsorption layer, but this retardation was only temporary due to significant changes in the pH. In contrast, the adsorption layer only retarded the migration of B to a limited extent. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,2347798,"Laboratory testing of trace metals removal from mine drainage and arsenic removal from groundwater in the Black Hills of South Dakota Abstract: The Gilt Edge Superfund Site is a former heap-leach gold mine that currently is being remediated in the Black Hills of South Dakota. Mine runoff water is treated before release from the site. The field pH, before treatment, is about 3; the water contains arsenic at low levels and some trace metals at elevated levels, in addition to total dissolved solids concentrations of more than 1,900 mg/L. In the Keystone area of the Black Hills, naturally occurring arsenic has been detected at elevated concentrations in groundwater samples from wells. The City of Keystone's Roy Street Well, which is not used currently, showed arsenic concentrations of 36 parts per billion and total dissolved solids of 320 mg/L. With field samples of water from the Gilt Edge site, a limestone-based method was successful in reducing trace metals concentrations to about 0.001 mg/L or less; at the Keystone site, the limestone method reduced arsenic levels to about 0.006 mg/L. The results are significant because previous research with the limestone-based method mainly had involved samples prepared with distilled water in the laboratory, in which interference of other ions such as sulfate did not occur. The research indicates the potential for broader applications of the limestone-based removal method, including scale-up work at field sites for water treatment.",
Arsenic,2337188,"Sulfur metabolism: Different tolerances of two aquatic macrophytes exposed to arsenic Abstract: The toxicity of arsenic (As) and the mechanisms of response to this pollutant were analyzed in two aquatic plant species, one sensitive and one tolerant to the pollutant, Salvinia minima and Lemna gibba, respectively. The plants, grown in nutrient solution at pH 6.5, were exposed to As concentrations of 0.0 and 1.0mgL(-1) for 3 days. Both species accumulated As in their tissues, which resulted in increases in H2O2 production. L. gibba accumulated eleven times more As than S. minima. However, L. gibba was more tolerant, as shown by the absence of cell membrane damage and, despite greater accumulation, smaller growth reduction than S. minima. Indeed, the index of tolerance to As was twenty percent higher in L. gibba than in S. minima, which most likely results from the presence of a more efficient defense system. This defense system in L. gibba is most likely based on sulfate absorption, assimilation and metabolism. L. gibba showed an increase in sulfate absorption and adenosine-5'-triphosphate (ATP) sulfurylase activity (the first enzyme of the inorganic sulfate assimilation pathway) following exposure to As. Consequently, the plant produced greater concentrations of sulfur-containing compounds that are involved in cellular detoxification, such as glutathione and non-protein thiols, and demonstrated greater enzymatic activity of ?-glutamylcysteine synthetase, glutathione S-transferase and glutathione reductase. Therefore, the plant?s ability to increase absorption, assimilation and metabolism of sulfur are key steps for tolerance to oxidative stress triggered by metals.",
Arsenic,1016102,"Association between arsenic exposure and behavior among first-graders from Torreón, Mexico Abstract: Previous studies suggest adverse effects of arsenic exposure on children's cognitive function. In this study, we examined the potential association between arsenic exposure and children's behavior. Five hundred and twenty-six children, 6-7 years old, living near a metal foundry in Torreón, Mexico, participated in the study. Arsenic exposure was measured as total urinary arsenic (UAs) and arsenic metabolites-monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) concentrations. Children's behavior was assessed by Conners Behavior Rating Scales for parents and teachers. The median (interquartile range) concentrations of UAs, MMA and DMA were 55.2 (39.7), 6.7 (5.9) and 39.3 (28.5) ?g/L, respectively. The mean behavior scores from parent and teacher ratings were within the clinically normal range (T&lt;65). The relationship between behavior and urinary arsenic was modeled in linear and logistic regression models, with UAs, MMA and DMA tested in separate models and entered as quartiles. No significant association was found between any measure of urinary arsenic and parent ratings of behavior. However, higher UAs was modestly associated with higher scores on the Oppositional, Cognitive Problems and ADHD sub-scales of the teacher ratings; a dose-response relationship was not established between UAs quartiles and behavior. Higher urinary DMA was associated with higher ratings on the Oppositional, Cognitive Problems and ADHD Index by teachers. The associations between UAs and behavior became statistically non-significant after adjustment for the Peabody Picture Vocabulary Test scores, suggesting that the harmful effects of arsenic on behavior may be secondary to arsenic-induced cognitive deficits. These data suggest a potential adverse association between arsenic and children's behavior and indicate a need to further study the effects of arsenic and arsenic metabolites on neurobehavioral outcomes in children.",
Arsenic,1597405,"Effects of natural and calcined poultry waste on Cd, Pb and As mobility in contaminated soil Abstract: ",
Arsenic,1342547,Inhibition of the Glucocorticoid Receptor Protects against Arsenic-Induced Birth Defects Abstract: ,
Arsenic,2088602,"Developmental Subchronic Exposure to Diphenylarsinic Acid Induced Increased Exploratory Behavior, Impaired Learning Behavior, and Decreased Cerebellar Glutathione Concentration in Rats Abstract: In Japan, people using water from the well contaminated with high-level arsenic developed neurological, mostly cerebellar, symptoms, where diphenylarsinic acid (DPAA) was a major compound. Here, we investigated the adverse effects of developmental exposure to 20mg/l DPAA in drinking water (early period [0-6 weeks of age] and/or late period [7-12]) on behavior and cerebellar development in male rats. In the open field test at 6 weeks of age, early exposure to DPAA significantly increased exploratory behaviors. At 12 weeks of age, late exposure to DPAA similarly increased exploratory behavior independent of the early exposure although a 6-week recovery from DPAA could reverse that change. In the passive avoidance test at 6 weeks of age, early exposure to DPAA significantly decreased the avoidance performance. Even at 12 weeks of age, early exposure to DPAA significantly decreased the test performance, which was independent of the late exposure to DPAA. These results suggest that the DPAA-induced increase in exploratory behavior is transient, whereas the DPAA-induced impairment of passive avoidance is long lasting. At 6 weeks of age, early exposure to DPAA significantly reduced the concentration of cerebellar total glutathione. At 12 weeks of age, late, but not early, exposure to DPAA also significantly reduced the concentration of cerebellar glutathione, which might be a primary cause of oxidative stress. Early exposure to DPAA induced late-onset suppressed expression of NMDAR1 and PSD95 protein at 12 weeks of age, indicating impaired glutamatergic system in the cerebellum of rats developmentally exposed to DPAA.",
Arsenic,1033430,"Cellular uptake and metabolic reduction of pentavalent to trivalent arsenic as determinants of cytotoxicity and morphological transformation Abstract: Cytotoxicity, morphological neoplastic transformation, cellular uptake and metabolic reduction were determined in BALB/3T3 Cl A31-1-1 cells for trivalent arsenic (sodium arsenite, As3+) and for pentavalent arsenic (sodium arsenate, As5+). The levels of cellular uptake of 73As-labelled sodium arsenite and arsenate were dose-dependent and highest in the first hour. At equimolar concentration (3 X 10(-6) M), cellular uptake was 4-fold higher for As3+ than for As5+. Cytotoxicity was higher for As3+ than for As5+, but when correlated to total As cell burden it showed no significant difference for the two forms. Morphological transformation focus assays showed transforming activity for both As3+ and As5+, with relative transformation frequencies also of approximately 4:1. Recovery from the cytosol after exposure for 1-24 h was greater than 90% for either form of absorbed As. Exposure to As3+ yielded 100% as As3+ in cytosol, but exposure to As5+ yielded greater than 70% as As3+, showing a high rate of intracellular metabolic reduction. No methylated metabolites were detected by ion-exchange chromatography. After 24-h incubation in cell-free medium, oxidation of As3+ to As5+ occurred up to 30% of the dose, but incubation in the presence of cells lowered the oxidation level to 4%. As5+ was recovered unchanged from cell-free medium (24-h incubation), but in the presence of the cells it yielded up to 5% as As3+ within 24 h and the cumulative release of As3+ by cells exposed to As5+ was dose-dependent. Glutathione depletion by diethylmaleate inhibited reduction of As5+ to As3+ by these cells up to 25% of controls, showing that As5+ reduction is partly dependent on glutathione. These results suggest that As3+ is the form responsible for the cytotoxic and transforming effects, independently of the valence state of the inorganic arsenic in the culture medium.",
Arsenic,1337542,"EMG biofeedback effectiveness to alter muscle activity pattern and scapular kinematics in subjects with and without shoulder impingement Abstract: BACKGROUND: Muscle imbalance between serratus anterior (SA), upper trapezius (UA), middle trapezius (MT), and lower trapezius (LT) muscles has been observed in subjects with subacromial impingement syndrome (SAIS). OBJECTIVE: (1) To investigate the effect of electromyography (EMG) biofeedback training on muscle balance ratios and scapular kinematics in healthy adults and subjects with SAIS. (2) To investigate whether the effects of EMG biofeedback on muscle balance ratios are different between groups. DESIGN: Twelve healthy adults and 13 subjects with SAIS were recruited in this study. EMG was used to record the activity of scapular muscles. The ratios (UT/SA, UT/MT, and UT/LT) during exercises with/without EMG biofeedback were calculated. Scapular kinematics were recorded before and after exercises with/without EMG biofeedback. RESULTS: For the subjects with SAIS, muscle balance ratios were lower during forward flexion with EMG biofeedback than during exercise only (UT/SA: 70.3-45.2; UT/LT: 124.8-94.6). Additionally, similar results were found during side-lying external rotation (UT/MT: 58.5-36.4). For the scapular upward rotation and tipping in both groups, there were no significant differences with and without EMG biofeedback. CONCLUSION: EMG biofeedback improved the scapular muscular balance during training exercises in both groups. Further clinical trials should investigate the long-term effects of EMG biofeedback.",
Arsenic,1029316,"Expression of a Pteris vittata glutaredoxin PvGRX5 in transgenic Arabidopsis thaliana increases plant arsenic tolerance and decreases arsenic accumulation in the leaves Abstract: Chinese brake fern Pteris vittata hyperaccumulates arsenic in its fronds. In a study to identify brake fern cDNAs in arsenic resistance, we implicated a glutaredoxin, PvGRX5, because when expressed in Escherichia coli, it improved arsenic tolerance in recombinant bacteria. Here, we asked whether PvGRX5 transgenic expression would alter plant arsenic tolerance and metabolism. Two lines of Arabidopsis thaliana constitutively expressing PvGrx5 cDNA were compared with vector control and wild-type lines. PvGRX5-expressors were significantly more tolerant to arsenic compared with control lines based on germination, root growth and whole plant growth under imposed arsenic stress. PvGRX5-expressors contained significantly lower total arsenic compared with control lines following treatment with arsenate. Additionally, PvGRX5-expressors were significantly more efficient in their arsenate reduction in vivo. Together, our results indicate that PvGRX5 has a role in arsenic tolerance via improving arsenate reduction and regulating cellular arsenic levels. Paradoxically, our results suggest that PvGRX5 from the arsenic hyperaccumulator fern can be used in a novel biotechnological solution to decrease arsenic in crops.",
Arsenic,2279583,"Role of competing ions in the mobilization of arsenic in groundwater of Bengal Basin: Insight from surface complexation modeling Abstract: This study assesses the role of competing ions in the mobilization of arsenic (As) by surface complexation modeling of the temporal variability of As in groundwater. The potential use of two different surface complexation models (SCMs), developed for ferrihydrite and goethite, has been explored to account for the temporal variation of As(III) and As(V) concentration, monitored in shallow groundwater of Bengal Basin over a period of 20 months. The SCM for ferrihydrite appears as the better predictor of the observed variation in both As(III) and As(V) concentrations in the study sites. It is estimated that among the competing ions, PO4(3-) is the major competitor of As(III) and As(V) adsorption onto Fe oxyhydroxide, and the competition ability decreases in the order PO4(3-) ? Fe(II) &gt; H4SiO4 = HCO3(-). It is further revealed that a small change in pH can also have a significant effect on the mobility of As(III) and As(V) in the aquifers. A decrease in pH increases the concentration of As(III), whereas it decreases the As(V) concentration and vice versa. The present study suggests that the reductive dissolution of Fe oxyhydroxide alone cannot explain the observed high As concentration in groundwater of the Bengal Basin. This study supports the view that the reductive dissolution of Fe oxyhydroxide followed by competitive sorption reactions with the aquifer sediment is the processes responsible for As enrichment in groundwater.",
Arsenic,1353219,"Arsenite pre-conditioning reduces UVB-induced apoptosis in corneal epithelial cells through the anti-apoptotic activity of 27 kDa heat shock protein (HSP27) Abstract: Exposure to ultraviolet (UV) light poses a health risk for eye disease, and solar ultraviolet in the B range (UVB, 280-320 nm) is known to be related to various corneal disorders. In this study, we investigated whether pre-conditioning of cells with arsenite (AsO2(-1)) can reduce UVB-induced apoptosis in human corneal epithelial cells, and whether the anti-apoptotic activity of 27 kDa heat shock protein (HSP27), a small heat shock protein, plays a role in this protection. UVB at levels comparable to physiologic solar exposure induces apoptosis of corneal epithelial cells in culture, demonstrated by activation of caspase 9 and caspase 3, and DNA fragmentation. When cells were pre-conditioned with arsenite prior to UVB exposure, the UVB-induced cell death was reduced, and UVB-induced activation of caspases and DNA fragmentation was inhibited. When cells were pre-treated with SB 203580, which inhibits HSP27 phosphorylation through inhibition of p38 MAP kinase activation, the arsenite-induced reduction of UVB-induced apoptosis was partially reversed. Arsenite pre-conditioning inhibited UVB-induced apoptosis in a two-phase pattern, which was temporally correlated with arsenite-induced HSP27 expression and phosphorylation. Neutralization of intracellular HSP27 with its antibody reduced arsenite's inhibition of UVB-induced caspase3 activation. Our results suggest that forms of stress that upregulate HSP27 and its phosphorylation may be useful as novel approaches to prevent adverse ocular effects arising from UV exposure in humans.",
Arsenic,1247658,"Arsenite-induced mitotic death involves stress response and is independent of tubulin polymerization Abstract: Arsenite, a known mitotic disruptor, causes cell cycle arrest and cell death at anaphase. The mechanism causing mitotic arrest is highly disputed. We compared arsenite to the spindle poisons nocodazole and paclitaxel. Immunofluorescence analysis of alpha-tubulin in interphase cells demonstrated that, while nocodazole and paclitaxel disrupt microtubule polymerization through destabilization and hyperpolymerization, respectively, microtubules in arsenite-treated cells remain comparable to untreated cells even at supra-therapeutic concentrations. Immunofluorescence analysis of alpha-tubulin in mitotic cells showed spindle formation in arsenite- and paclitaxel-treated cells but not in nocodazole-treated cells. Spindle formation in arsenite-treated cells appeared irregular and multi-polar. gamma-tubulin staining showed that cells treated with nocodazole and therapeutic concentrations of paclitaxel contained two centrosomes. In contrast, most arsenite-treated mitotic cells contained more than two centrosomes, similar to centrosome abnormalities induced by heat shock. Of the three drugs tested, only arsenite treatment increased expression of the inducible isoform of heat shock protein 70 (HSP70i). HSP70 and HSP90 proteins are intimately involved in centrosome regulation and mitotic spindle formation. HSP90 inhibitor 17-DMAG sensitized cells to arsenite treatment and increased arsenite-induced centrosome abnormalities. Combined treatment of 17-DMAG and arsenite resulted in a supra-additive effect on viability, mitotic arrest, and centrosome abnormalities. Thus, arsenite-induced abnormal centrosome amplification and subsequent mitotic arrest is independent of effects on tubulin polymerization and may be due to specific stresses that are protected against by HSP90 and HSP70.",
Arsenic,1519082,"Arsenic toxicity in the human nerve cell line SK-N-SH in the presence of chromium and copper Abstract: As, Cr, and Cu represent one potential combination of multiple metals/metalloids exposures since these three elements are simultaneously leached from chromated copper arsenate (CCA)-treated wood, a common product used for building construction, at levels that can be potentially harmful. This study investigated the neurotoxicity of As associated with CCA-treated wood when accompanied by Cr and Cu. The toxicity was evaluated on the basis of a cytotoxicity model using human neuroblastoma cell line SK-N-SH. The cells were cultured with CCA-treated wood leachates or with solutions containing arsenate [As(V)], divalent copper [Cu(II)], trivalent chromium [Cr(III)] alone or in different combinations of the three elements. The toxicity was evaluated using variations in cell replication compared to controls after 96h exposure. Among the three elements present in wood leachates, As played the primary role in the observed toxic effects, which were exerted through multiple pathways, including the generation of oxidative stress. DOM affected the absorption of metals/metalloids into the test cells, which however did not obviously appear to impact toxicity. As toxicity was enhanced by Cu(II) and inhibited by Cr(III) at concentrations below U.S. EPA's allowable maximum contaminant levels in drinking waters. Thus assessing As toxicity in real environments is not sufficient if based solely on the result from As.",
Arsenic,1247808,"Inorganic arsenic represses interleukin-17A expression in human activated Th17 lymphocytes Abstract: Trivalent inorganic arsenic [As(III)] is an efficient anticancer agent used to treat patients suffering from acute promyelocytic leukemia. Recently, experimental studies have clearly demonstrated that this metalloid can also cure lymphoproliferative and/or pro-inflammatory syndromes in different murine models of chronic immune-mediated diseases. T helper (Th) 1 and Th17 lymphocytes play a central role in development of these diseases, in mice and humans, especially by secreting the potent pro-inflammatory cytokine interferon-? and IL-17A, respectively. As(III) impairs basic functions of human T cells but its ability to modulate secretion of pro-inflammatory cytokines by differentiated Th lymphocytes is unknown. In the present study, we demonstrate that As(III), used at concentrations clinically achievable in plasma of patients, has no effect on the secretion of interferon-? from Th1 cells but almost totally blocks the expression and the release of IL-17A from human Th17 lymphocytes co-stimulated for five days with anti-CD3 and anti-CD28 antibodies, in the presence of differentiating cytokines. In addition, As(III) specifically reduces mRNA levels of the retinoic-related orphan receptor (ROR)C gene which encodes ROR?t, a key transcription factor controlling optimal IL-17 expression in fully differentiated Th17 cells. The metalloid also blocks initial expression of IL-17 gene induced by the co-stimulation, probably in part by impairing activation of the JNK/c-Jun pathway. In conclusion, our results demonstrate that As(III) represses expression of the major pro-inflammatory cytokine IL-17A produced by human Th17 lymphocytes, thus strengthening the idea that As(III) may be useful to treat inflammatory immune-mediated diseases in humans.",
Arsenic,1337711,"Arsenic occurrence and accumulation in soil and water of eastern districts of Uttar Pradesh, India Abstract: Arsenic in the soil and water of eastern districts of Uttar Pradesh (Ballia and Ghazipur) was estimated. Survey results revealed that arsenic in soil samples ranged from 5.40 to 15.43 parts per million (ppm). In water samples, it ranged from 43.75 to 620.75 parts per billion (ppb) which far exceeded the permissible limit of 10 ppb as recommended by the World Health Organization. Maximum concentration of arsenic in water was found in Haldi village of Ballia (620.75 ppb). However, mean arsenic concentration in water followed the order: Karkatpur (257.21 ppb) &lt; Haldi (310.15 ppb) &lt; Sohaon (346.94 ppb) &lt; Dharmarpur (401.75 ppb). In case of soil, maximum arsenic was detected in soil of Sohaon (15.43 ppm). Mean arsenic levels in soils followed the order: Karkatpur (9.24 ppm) &lt; Haldi (9.82 ppm) &lt; Dharmarpur (11.32 ppm) &lt; Sohaon (14.08 ppm). Arsenic levels were higher in soils collected from 15-30 cm depth than 0-15 cm from the soil surface.",
Arsenic,1508608,"Differential modulation of cytochrome P450 1a1 by arsenite in vivo and in vitro in C57BL/6 mice Abstract: Heavy metals, typified by arsenite (As(III)), have been implicated in altering the carcinogenicity of aryl hydrocarbon receptor (AhR) ligands, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), by modulating the induction of the Cyp1a1 enzyme, but the mechanism remains unresolved. In this study, the effects of As(III) on Cyp1a1 expression and activity were investigated in C57BL/6 mouse livers and isolated hepatocytes. For this purpose, C57BL/6 mice were injected intraperitoneally with As(III) (12.5mg/kg) in the absence and presence of TCDD (15?g/kg) for 6 and 24h. Furthermore, isolated hepatocytes from C57BL/6 mice were treated with As(III) (1, 5, and 10?M) in the absence and presence of TCDD (1nM) for 3, 6, 12, and 24h. At the in vivo level, As(III) decreased the TCDD-mediated induction of Cyp1a1 mRNA at 6h while potentiating its mRNA, protein, and catalytic activity levels at 24h. At the in vitro level, As(III) decreased the TCDD-mediated induction of Cyp1a1 mRNA in a concentration- and time-dependent manner. Moreover, As(III) decreased the TCDD-mediated induction of Cyp1a1 protein and catalytic activity levels at 24h. Interestingly, As(III) increased the serum hemoglobin (Hb) levels in animals treated for 24h. Upon treatment of isolated hepatocytes with Hb alone, there was an increase in the nuclear accumulation of AhR and AhR-dependent luciferase activity. Furthermore, Hb potentiated the TCDD-induced AhR-dependent luciferase activity. Importantly, when isolated hepatocytes were treated for 5h with As(III) in the presence of TCDD and the medium was then replaced with new medium containing Hb, there was potentiation of the TCDD-mediated effect. Taken together, these results demonstrate for the first time that there is a differential modulation of the TCDD-mediated induction of Cyp1a1 by As(III) in C57BL/6 mouse livers and isolated hepatocytes. Thus, this study implicates Hb as an in vivo-specific modulator.",
Arsenic,626940,"Arsenic alters cytosine methylation patterns of the promoter of the tumor suppressor gene p53 in human lung cells: a model for a mechanism of carcinogenesis Abstract: Arsenic is a potent human carcinogen to which there is significant worldwide exposure through natural contamination of food and drinking water sources. Because arsenic is detoxified via methylation using a methyltransferase (MTase) and S-adenosylmethionine (SAM) as the methyl donor, we hypothesized that a mechanism of carcinogenesis of arsenic could involve alterations of MTase/SAM-dependent DNA methylation of a tumor suppressor gene. We found that exposure of human lung adenocarcinoma A549 cells to sodium arsenite (0.08 – 2 ?M) or sodium arsenate (30–300 ?M), but not dimethylarsenic acid (2–2000 ?M), produced significant dose-responsive hypermethylation within a 341-base pair fragment of the promoter of p53. This was determined by quantitative PCR/HpaII restriction site analysis to analyze methylation status of two CCGG sites. In experiments with arsenite, DNA sequencing using bisulfite to visualize 5-methylcytosine (5-MeC) over the entire promoter region confirmed data obtained by restriction analysis. Limited data using SssI methylase also suggested that over-methylation of CpG sequences may exist over the entire genome in response to arsenite exposure. We propose that alteration of DNA methylation by arsenic offers a plausible, unified hypothesis for the carcinogenic mechanism of action of arsenic, and we present a model for arsenic carcinogenesis that utilizes perturbations of DNA methylation as the basis for the carcinogenic effects of arsenic.",
Arsenic,627304,"Therapeutic value of Hippophae rhamnoides L. against subchronic arsenic toxicity in mice Abstract: The present study was planned to investigate the therapeutic efficacy of Hippophae rhamnoides L. against the toxic effects of arsenic in mice. H. rhamnoides L. is used as an herbal remedy for gastric ulcers, burns, and some skin and allergic diseases. Twenty-five Swiss albino mice were exposed to arsenic (25 ppm) in drinking water for 3 months. After 3 months different fruit extracts of H. rhamnoides L. (500 mg/kg for 10 days) were administered, the animals were sacrificed, and blood and tissues were assayed for various biochemical indicators of oxidative stress and whether arsenic was removed from tissues. Treatment with different fruit extracts of H. rhamnoides L. showed significant protection from arsenic inhibition of blood delta-aminolevulinic acid dehydratase activity and restored blood reduced glutathione levels. Other hematologic variables like white blood cell counts, hemoglobin, and hematocrit were partially protected by supplementation with a water extract of H. rhamnoides L. (HF-WRT). Significant protection was also observed in altered hepatic, renal, and brain reduced/ oxidized glutathione ratio and thiobarbituric acid-reactive substances levels. The aqueous extract of H. rhamnoides L. (HF-WRT) also provided protection against parameters indicative of liver injury such as aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities. There was also no effect on blood and tissue arsenic concentrations observed except some moderate depletion of blood arsenic concentrations, suggesting that the drug has no ability to chelate intracellular arsenic. It can be concluded from these results that post-treatment with an aqueous extract of H. rhamnoides L. (HF-WRT) significantly protects against arsenic-induced oxidative stress but does not chelate arsenic, suggesting it may have a beneficial role as a supplementing agent during chelation of arsenic by other means.",
Arsenic,1509355,"The impact of process sequences on pollutant removal efficiencies in tannery wastewater treatment Abstract: A laboratory-scale study was conducted to determine the removal efficiencies of nine contaminants from a tannery wastewater using a number of physicochemical processes. Coagulation–flocculation using bittern as coagulant, oxidation-utilizing ozone, and adsorption using activated carbon were applied separately and in different sequences. Jar tests were utilized to conduct the experimental work. Except for arsenic, the highest removal efficiencies were recorded when coagulation/flocculation was conducted on the alkalized samples using a bittern dose of 5 mL/L. Activated carbon adsorption improved removal efficiencies of several contaminants. The coagulation/flocculation–adsorption sequence using the optimum dose of 5 mL/L of bittern resulted in high removal efficiencies for total suspended solids (TSS) (97 %?±?1), apparent color (100 %?±?0), turbidity (97 %?±?1), total nitrogen (86 %?±?1), and chromium (100 %?±?0). On the other hand, the same sequence resulted in moderate removal efficiencies for chemical oxygen demand (COD) (72 %?±?7) and total phosphorus (74 %?±?5) and relatively low removals for biochemical oxygen demand (BOD) (55 %?±?10) and arsenic (42 %?±?14). The removal efficiencies for the different tested sequences demonstrated that each sequence did improve the removal efficiencies for most of the parameters tested and consequently, the quality of tannery effluent. However, no single optimum sequence was capable of attaining high removal efficiencies for all nine parameters.",
Arsenic,1794779,"The effect of air pollution on stone decay: The decay of the Drachenfels trachyte in industrial, urban, and rural environments - A case study of the Cologne, Altenberg and Xanten cathedrals Abstract: Severe stone deterioration is evident at the Cologne cathedral. In particular, the ""Drachenfels"" trachyte, which was the building material of the medieval construction period, shows significant structural deterioration as well as massive formation of gypsum crusts. The present article investigates crust formation on limestone, sandstone, and volcanic rock from the Cologne cathedral as well as from the Xanten and Altenberg cathedrals. These three buildings, showing varying degrees of deterioration, are located in different areas and exposed to varying industrial, urban, and rural pollution. Thin laminar and black framboidal crusts form on calcareous as well as silicate stone. The lack of a significant intrinsic calcium and sulfur source for the formation of the gypsum crusts on the Drachenfels trachyte indicates major extrinsic environmental impact: a sufficient offer of SO (x) from pollutant fluxes as well as external calcium sources (e.g., pollution, mortars, neighboring calcite stones). Chemical analyses reveal strong gypsum enrichment within the crusts as well as higher concentrations of lead and other pollutants (arsenic, antimony, bismuth, tin, etc.), which generally can be linked to traffic and industry. The formation of weathering crusts in an industrial environment is clearly distinguishable from that in rural areas. Scanning electron microscopy observations confirm that the total amount of pollution is less at the Altenberg cathedral than at the Cologne and Xanten cathedrals. XRF analyses show that the formation of gypsum occurs in lower amounts at Altenberg. This correlates well with the measured SO2 content and the intensity of the decay at the different locations. Furthermore, the different types of crusts, e.g., framboidal and laminar, can be differentiated and assigned to the different locations. The black weathering crusts on the silicate Drachenfels trachyte contribute to the degradation of the historic building material. They enhance mechanical moisture-related deterioration processes and the decay by chemical corrosion of rock-forming minerals. Although SO2 concentrations in air have shown a strong decrease over the past 30 years, degradation in connection with weathering crusts is still observed. This indicates that not only contemporary or recent emissions, but also past pollutant concentrations have to be considered.",
Arsenic,1021603,"Arsenic-contaminated cold-spring water in mountainous areas of Hui County, Northwest China: a new source of arsenic exposure Abstract: Although pump-well is the primary drinking water source in rural areas of China, there are still 8.4% of villages reliant on cold-spring. In this study, a survey of arsenic concentration in cold-springs and pump-wells was carried out in Hui County, Northwest China. A total of 352 drinking water samples, including 177 cold-springs and 175 pump-wells, were collected. The maximum arsenic concentrations in cold-springs and pump-wells were 0.482 mg/L and 0.067 mg/L, respectively. We found that 15.8% (28) of total cold-springs and 1.1% (2) of total pump-wells had arsenic concentrations exceeding the maximum allowable concentration of arsenic in drinking water of rural China (0.05 mg/L). Our findings show that 5 cold spring-contaminated villages are located in the mountainous areas of Hui County and 2224 inhabitants may be at risk of high arsenic exposure. This paper indicates that arsenic contamination of cold-springs may be more serious than expected in mountainous areas of Northwest China and extensive surveys and epidemiological studies should be carried out to investigate the potential contaminated areas and affected population.",
Arsenic,1704132,"Arsenic and mercury in the soils of an industrial city in the Donets Basin, Ukraine Abstract: Soil and house dust collected in and around Hg mines and a processing facility in Horlivka, a mid-sized city in the Donets Basin of southeastern Ukraine, have elevated As and Hg levels. Surface soils collected at a former Hg-processing facility had up to 1300 mg kg-1 As and 8800 mg kg-1 Hg; 1M HCl extractions showed 74-93% of the total As, and 1-13% of the total Hg to be solubilized, suggesting differential environmental mobility between these elements. In general, lower extractability of As and Hg was seen in soil samples up to 12 km from the Hg-processing facility, and the extractable (1M HCl, synthetic precipitation, deionized water) fractions of As are greater than those for Hg, indicating that Hg is present in a more resistant form than As. The means (standard deviation) of total As and Hg in grab samples collected from playgrounds and public spaces within 12 km of the industrial facility were 64 (±38) mg kg-1 As and 12 (±9.4) mg kg-1 Hg; all concentrations are elevated compared to regional soils. The mean concentrations of As and Hg in dust from homes in Horlivka were 5-15 times higher than dust from homes in a control city. Estimates of possible exposure to As and Hg through inadvertent soil ingestion are provided.",
Arsenic,1015778,"Seminal plasma metals concentration with respect to semen quality Abstract: The aim of the current study was to assess relationships between multiple metals burden in human seminal plasma and semen quality parameters. Levels of five metals (lead, manganese, copper, arsenic, and selenium) in human seminal plasma were determined by inductively coupled plasma mass spectrometry (ICP-MS), and the correlations between the metal concentrations and semen parameters (sperm concentration, sperm motility rate, and sperm morphology) were analyzed. The activities of acid phosphatase (ACP) and of ?-glucosidase in human seminal plasma were also determined. Of the 100 subjects, 21 had fertility problems according to the World Health Organization criteria and were designated as &quot;abnormal group.&quot; Significant inverse correlations were found between the concentrations of Cu, As, Pb, and the sperm concentrations (r (Cu)?=?-0.312, P (Cu)?=?0.029; r (As)?=?-0.328, P (As)?=?0.021; r (Pb)?=?-0.377, P (Pb)?=?0.008). Moreover, the Cu, Mn, and Se concentrations were significantly higher in the abnormal group than that in the normal group (P (Cu)?=?0.024, P (Mn)?=?0.002, P (Se)?=?0.002). The ACP activity was significantly higher in the normal group than that in the abnormal group (P?=?0.021). We also found a significantly negative correlation between ?-glucosidase activity and the levels of As (r?=?-0.367, P?=?0.023). These findings provide evidence for relationships between human semen quality and metal exposures. These relationships are consistent with animal data, but additional human and mechanistic studies are needed.",
Arsenic,2337093,"Increased bioavailability of metals in two contrasting agricultural soils treated with waste wood-derived biochar and ash Abstract: Recycled waste wood is being increasingly used for energy production; however, organic and metal contaminants in by-products produced from the combustion/pyrolysis residue may pose a significant environmental risk if they are disposed of to land. Here we conducted a study to evaluate if highly polluted biochar (from pyrolysis) and ash (from incineration) derived from Cu-based preservative-treated wood led to different metal (e.g., Cu, As, Ni, Cd, Pb, and Zn) bioavailability and accumulation in sunflower (Helianthus annuus L.). In a pot experiment, biochar at a common rate of 2 % w/w, corresponding to ?50 t ha(-1), and an equivalent pre-combustion dose of wood ash (0.2 % w/w) were added to a Eutric Cambisol (pH 6.02) and a Haplic Podzol (pH 4.95), respectively. Both amendments initially raised soil pH, although this effect was relatively short-term, with pH returning close to the unamended control within about 7 weeks. The addition of both amendments resulted in an exceedance of soil Cu statutory limit, together with a significant increase of Cu and plant nutrient (e.g., K) bioavailability. The metal-sorbing capacity of the biochar, and the temporary increase in soil pH caused by adding the ash and biochar were insufficient to offset the amount of free metal released into solution. Sunflower plants were negatively affected by the addition of metal-treated wood-derived biochar and led to elevated concentration of metals in plant tissue, and reduced above- and below-ground biomass, while sunflower did not grow at all in the Haplic Podzol. Biochar and ash derived from wood treated with Cu-based preservatives can lead to extremely high Cu concentrations in soil and negatively affect plant growth. Identifying sources of contaminated wood in waste stream feedstocks is crucial before large-scale application of biochar or wood ash to soil is considered.",
Arsenic,1252655,Determination of arsenic and selenium in fat materials and petroleum products by oxygen bomb combustion and automated atomic absorption spectrometry with hydride generation Abstract: ,
Arsenic,1453803,"Early exposure to toxic metals has a limited effect on blood pressure or kidney function in later childhood, rural Bangladesh Abstract: BACKGROUND: Chronic exposure to toxic metals such as arsenic and cadmium has been implicated in the development of kidney and cardiovascular diseases but few studies have directly measured exposure during inutero and early child development. METHODS: We investigated the impact of exposure to arsenic (mainly in drinking water) and cadmium (mainly in rice) during pregnancy on blood pressure and kidney function at 4.5 years of age in rural Bangladesh. The effect of arsenic exposure in infancy was also assessed. RESULTS: Within a cohort of 1887 children recruited into the MINIMat study, exposure to arsenic (maternal urinary arsenic, U-As), but not cadmium, during in utero development was associated with a minimal increase in blood pressure at 4.5 years. Each 1 mg/l increase in pregnancy U-As was associated with 3.69 mmHg (95% CI: 0.74, 6.63; P: 0.01) increase in child systolic and a 2.91 mmHg (95% CI: 0.41, 5.42; P: 0.02) increase in child diastolic blood pressure. Similarly, a 1 mg/l increase in child U-As at 18 months of age was associated with a 8.25 mmHg (95% CI: 1.37, 15.1; P: 0.02) increase in systolic blood pressure at 4.5 years. There was also a marginal inverse association between infancy U-As and glomerular filtration rate at 4.5 years (-33.4 ml/min/1.72 m(2); 95% CI: -70.2, 3.34; P: 0.08). No association was observed between early arsenic or cadmium exposure and kidney volume at 4.5 years assessed by ultrasound. CONCLUSIONS: These modest effect sizes provide some evidence that arsenic exposure in early life has long-term consequences for blood pressure and maybe kidney function.",
Arsenic,1519223,"Cellular acidosis inhibits assembly, disassembly, and motility of stress granules Abstract: Stress granules (SGs) are large ribonucleoprotein (RNP)-containing particles that form in cytoplasm in response to a variety of acute changes in the cellular environment. One of the general parameters of the cell environment is pH. In some diseases, as well as in muscle fatigue, tissue acidosis occurs, leading to decrease in intracellular pH. Here we studied whether decrease in pH causes the formation of SGs in cultured animal cells, whether it affects the formation of the SGs under the action of arsenite and, if such effects occur, what are the mechanisms of the influence of acidosis. Acidosis was simulated by decreasing the pH of the culture medium, which acidified the cytoplasm. We found that medium acidification to pH 6.0 in itself did not cause formation of SGs in cells. Moreover, acidification prevented the formation of SGs under treatment with sodium arsenite or sodium arsenite together with the proteasome inhibitor MG132, and it inhibited the dissociation of preformed SGs under the influence of cycloheximide. We established that pH decrease did not affect the phosphorylation of eIF2? that occurs under the action of sodium arsenite, and even caused such phosphorylation by itself. We also found that the velocity of SG motion in cytoplasm at acidic pH was very low, and the mobile fraction of SG-incorporated PABP protein revealed by FRAP was decreased. We suppose that acidic pH impairs biochemical processes favoring assembly of RNPs in stress conditions and RNP dissociation on the termination of stress. Thus, in acidosis the reaction of the cellular translation apparatus to stress is modified.",
Arsenic,1349505,Study on new spectrophotometric determination of arsenic (V) with chlorpromazine Abstract: ,
Arsenic,1339161,"Bradykinin-mediated angioedema: Factors prompting ED visits Abstract: <strong>OBJECTIVE: </strong>Bradykinin-mediated angioedema (AE) is characterized by periodic subcutaneous or submucosal swelling, with the absence of urticaria and itching. It affects the face and extremities. Attacks of abdominal pain and obstruction of the upper airways are the hallmarks of disease severity. The aim of this study was to determine the factors prompting patients to turn up at the hospital emergency department (ED) in the event of an attack.<br /><br /><strong>METHODS: </strong>This was a retrospective review of attacks experienced by all patients with bradykinin-mediated AE (hereditary, acquired, or drug-induced) who visited our ED between January 2002 and March 2011. Characteristics of attacks prompting ED visits and attacks when patients stayed at home were compared using logistic regression with generalized estimating equations to take into account the correlation between multiple attacks from the same patient.<br /><br /><strong>RESULTS: </strong>A total of 55 patients were included, of whom 39 had hereditary AE; 13, drug-induced AE; and 3, acquired C1 inhibitor deficiency. The median follow-up was 32 months (interquartile range, 10-99 months). The attack was severe in 324 (58%) of 559 cases. Thirty-two patients (58%) visited the ED for a total of 75 attacks. First attack and laryngeal edema were significantly associated with more frequent ED visits (odds ratio, 5.28 [95% confidence interval, 2.42-11.5] and 4.83 [1.54-15.5], respectively]. C1 inhibitor concentrate and icatibant treatment was significantly more often administered in the ED than at home (odds ratio, 4.9 [2.43-9.88] and 8.25 [2.4-28.3], respectively).<br /><br /><strong>CONCLUSIONS: </strong>First attack of bradykinin AE and swelling of the larynx were significantly associated with visits to the ED.",
Arsenic,627348,"Associations between arsenic in drinking water and pterygium in southwestern Taiwan Abstract: Pterygium is a fibrovascular growth of the bulbar conjunctiva and underlying subconjunctival tissue that may cause blindness. The mechanism of pterygium formation is not yet fully understood, but pterygium has some tumorlike features.<br /><br /> The objective of this study was to evaluate the association between arsenic exposure through drinking water and the occurrence of pterygium in southwestern Taiwan.<br /><br /> We recruited participants &gt; 40 years of age from three villages in the arseniasis-endemic area in southwestern Taiwan (exposure villages) and four neighboring nonendemic villages (comparison villages). Each participant received an eye examination and a questionnaire interview. Photographs taken of both eyes were later graded by an ophthalmologist to determine pterygium status.<br /><br /> We included 223 participants from the exposure villages and 160 from the comparison villages. The prevalence of pterygium was higher in the exposure villages across all age groups in both sexes and increased with cumulative arsenic exposure. We found a significant association between cumulative arsenic exposure and the prevalence of pterygium. After adjusting for age, sex, working under sunlight, and working in sandy environments, we found that cumulative arsenic exposure of 0.1-15.0 mg/L-year and &gt; or = 15.1 mg/L-year were associated with increased risks of developing pterygium. The adjusted odds ratios were 2.04 [95% confidence interval (CI), 1.04-3.99] and 2.88 (95% CI, 1.42-5.83), respectively.<br /><br /> Chronic exposure to arsenic in drinking water was related to the occurrence of pterygium, and the association was still observed after adjusting for exposures to sunlight and sandy environments.",
Arsenic,627531,"Modulation of murine peritoneal macrophage function by chronic exposure to arsenate in drinking water Abstract: Exposure of humans to arsenic is associated with various adverse health effects including immunotoxicity and elevated risk of cancer development. Specific mechanisms of these effects are not well understood. In the present study we investigated some functional parameters of peritoneal macrophages isolated from mice exposed for 12 weeks to sodium arsenate in drinking water at 0.5, 5, and 50 mgAs/l. The experimental conditions were matched with the environmental conditions of arsenic exposure in humans. To characterize function of the macrophages, we assessed their ability to release nitric oxide (NO), reactive oxygen species (ROS), and tumor necrosis factor-alpha (TNF-alpha) in response to common stimulants. To this end the isolated cells were stimulated with lipopolysaccharide (1 microg/ml) to assess NO and TNF-alpha production (the WEHI-164 bioassay) or with phorbol myristate acetate (5 microg/ml) to assess superoxide production (NBT reduction test). As a result, in mice exposed to 0.5, 5, and 50 mgAs/l we observed decreased production of NO (9 +/- 2, 8 +/- 2, 11 +/- 5 microM NO2-, respectively, versus 27 +/- 7 microM in control) and superoxide (41.3 +/- 18.2%, 52.8 +/- 15.1% and 55.9 +/- 12.9%, respectively, less than in control). Despite reduced NO production, expression of iNOS mRNA in RT-PCR, showed similar levels in exposed and control animals. We did not see any significant influence of the exposure on TNF-alpha release and mRNA expression. The potential consequences of decreased production of NO and superoxide by peritoneal macrophages as observed in exposed mice may suggest impaired response of the cells against infection or developing tumor cells.",
Arsenic,2337223,"ACTIVE REMOVAL OF INORGANIC PHOSPHATE FROM CEREBROSPINAL FLUID BY THE CHOROID PLEXUS Abstract: The inorganic phosphate (Pi) concentration of mammalian cerebrospinal fluid (CSF) is about one-half that of plasma, a phenomenon also shown here in the spiny dogfish, Squalus acanthias. The objective of the present study was to characterize the possible role of the choroid plexus (CP) in determining CSF [Pi]. The large sheet-like IVth CP of the shark was mounted in Ussing chambers where unidirectional (33)Pi fluxes revealed potent active transport from CSF to blood side under short-circuited conditions. The flux ratio was 8:1 with an average transepithelial resistance of 87 ± 17.9 ? x cm(2) and electrical potential difference of +0.9 ± 0.17 mV, CSF side positive. The active Pi absorption from CSF was inhibited by 10 mM arsenate, 0.2 mM ouabain, Na(+)-free medium, and by increasing [K(+)] from 5 mM to 100 mM. Li(+) stimulated transport 2-fold compared to Na(+)-free medium. Phosphonoformic acid (1 mM) had no effect on active Pi transport. RT-PCR revealed both PiT1 and PiT2 (SLC20 family) gene expression, but no NaPiII (SLC34 family) expression, in the shark CP. PiT2 immunoreactivity was shown by immunoblot, and localized by immunohistochemistry in (or near) the CP apical microvillar membranes of both shark and rat. PiT1 appeared to be localized primarily to the vascular endothelial cells. Together, the data indicate that the CP actively removes Pi from the CSF. This process has transport properties consistent with a PiT-2, Na(+)-dependent transporter which is located in the apical region of the CP epithelium.",
Arsenic,1346416,"The role of Glomus mosseae on key physiological and biochemical parameters of pea plants grown in arsenic contaminated soil Abstract: Arbuscular mycorrhiza (AM) constitutes a key functional group of soil biota that can greatly contribute to ecosystem sustainability by playing a critical role in stress tolerance. The effects of arsenic (As) stress on physiological and biochemical mechanisms and the role of Glomus mosseae (AM) in reducing As accumulation was investigated in Pisum sativum L. (pea). As uptake and accumulation increased with an increase in external As concentration, increment being higher in roots than in shoots. Sodium arsenate significantly affected shoot and root dry matter yield, damaged chlorophyll pigments and induced oxidative stress by decreasing membrane stability and increasing H2O2 production in a concentration dependent manner. The phytotoxicity of arsenate (AsV) led to an increase in superoxide dismutase, catalase and peroxidase activities and synthesis of osmolytes such as soluble sugars, proline, glycine betaine and total proteins. Establishment of association with G. mosseae reduced As(V) uptake and increased N, P, K+ as well as plant growth. AM inoculations alleviated As(V) toxicity by reducing oxidative stress and modulating antioxidative mechanisms in pea plants.",
Arsenic,1251427,"150-kDa oxygen-regulated protein (ORP150) suppresses hypoxia-induced apoptotic cell death Abstract: To determine the contribution of 150-kDa oxygen-regulated protein (ORP150) to cellular processes underlying adaptation to hypoxia, a cell line stably transfected to overexpress ORP150 antisense RNA was created. In human embryonic kidney (HEK) cells stably overexpressing ORP150 antisense RNA, ORP150 antigen and transcripts were suppressed to low levels in normoxia and hypoxia, whereas wild-type cells showed induction of ORP150 with oxygen deprivation. Inhibition of ORP150 in antisense transfectants was selective, as hypoxia-mediated enhancement of glucose-regulated protein (GRP) 78 and GRP94 was maintained. However, antisense ORP150 transfectants displayed reduced viability when subjected to hypoxia, compared with wild-type and sense-transfected HEK cells. In contrast, diminished levels of ORP150 had no effect on cytotoxicity induced by other stimuli, including oxygen-free radicals and sodium arsenate. Although cellular ATP content was similar in hypoxia, compared with ORP150 antisense transfectants and wild-type HEK cells, suppression of ORP150 expression was associated with accelerated apoptosis. Hypoxia-mediated cell death in antisense HEK transfectants did not cause an increase in caspase activity or in cytoplasmic cytochrome c antigen. A well recognized inducer of apoptosis in HEK cells, staurosporine, caused increased caspase activity and cytoplasmic cytochrome c levels in both wild-type and antisense cells. These data indicate that ORP150 has an important cytoprotective role in hypoxia-induced cellular perturbation and that ORP150-associated inhibition of apoptosis may involve mechanisms distinct from those triggered by other apoptotic stimuli.",
Arsenic,2347736,"Facile synthesis of magnetic nanocomposites of cellulose@ultrasmall iron oxide nanoparticles for water treatment Abstract: We report a facile in situ approach to synthesize magnetic nanocomposites of cellulose@ultrasmall iron oxide nanoparticles by co-precipitation using ionic liquid as co-solvent for cellulose and iron salt. The as-prepared gamma-Fe2O3 nanoparticles showed ultrasmall particle size (similar to 4.6 nm) and uniform distribution (the standard deviation is less than 10%). The magnetic nanocomposites displayed excellent adsorption efficiency for Pb(II) and methylene blue compared with other reported magnetic materials. The adsorption capacities of the magnetic nanospheres for the removal of Pb(II) and methylene blue were 21.5 and 40.5 mg g(-1), respectively. Furthermore, the prepared magnetic nanoadsorbent could be efficiently recycled and reused by applying an external magnetic field. The approach presented in this paper promotes the use of renewable natural resources to prepare a variety of hybrid inorganic-organic materials for the purpose of adsorbents, biomedical and other potential applications.",
Arsenic,627204,"An epidemiologic study of arsenic-related skin disorders and skin cancer and the consumption of arsenic-contaminated well Waters in Huhhot, Inner Mongolia, China Abstract: Well-use histories were obtained and dermatological examinations were conducted for 3,179 of the 3,228 (98.5%) residents of 3 villages in Inner Mongolia with well water arsenic levels as high as 2,000 ppb (ug/L). Eight persons were found to have skin cancer, 172 had hyperkeratoses, 121 had dyspigmentation, 94 had both hyperkeratoses and dyspigmentation, and, strikingly, none had Blackfoot disease. All 8 subjects with skin cancer also had both hyperkeratoses and dyspigmentation. Arsenic levels were measured for 184 wells and individual well-use histories were obtained. Arsenic exposure histories were summarized as both highest arsenic concentration (highest exposure level for at least 1-year duration) and cumulative arsenic exposure (ppb-years). Sixty-nine percent of the participants had highest arsenic concentrations below 100 ppb; 71% had cumulative arsenic exposures below 2,000 ppb-years. Exposure-response analyses included frequency-weighted, simple linear regression, and most-likely estimate (hockey-stick) models. Skin cancer cases were only found for those with a highest arsenic concentration greater than 150 ppb, and those with exposure less than 150 ppb had a statistically significant deficit. A frequency-weighted model showed a threshold at 150 ppb, and a hockey-stick model showed a threshold at 122 ppb. Considerations of duration, age, latency, and misclassification did not appear to markedly affect the analysis. The non-malignant skin findings showed thresholds of 40–50 ppb in the hockey-stick models. Application of these analytic models to the data from other epidemiological studies of arsenic ingestion and malignant and non-malignant skin disorders can be used to examine patterns of arsenic carcinogenicity.",
Arsenic,2278035,"Adsorption characteristics of arsenic from micro-polluted water by an innovative coal-based mesoporous activated carbon Abstract: An innovative coal-based mesoporous activated carbon (NCPAC) was prepared by re-agglomeration, oxidation and two-step activation using coal-blending as precursor. Adsorption capacities of As(III) and As(V) ions (&lt;0.5mg/L) onto NCPAC as a function of pH, adsorbent dose, initial arsenic concentrations, contact time, and adsorption isotherms at 7°C was investigated. The innovative methods promoted total pore volume (1.087cm(3)/g), mesoporosity (64.31%), iodine numbers (1104mg/g), methylene blue (251.8mg/g) and ash contents (15.26%). The adsorption capacities of NCPAC for As(III) and As(V) were found to be strongly dependent on pH and contact time. The optimal pH value was 6. The equilibrium time was 60min for adsorption of As(III) and As(V) by NCPAC. The Langmuir model fitted the experimental data well for both As(III) (R(2)=0.9980) and As(V) (R(2)=0.9988). Maximum adsorption capacities of As(III) and As(V) (C0=0.50mg/L) by NCPAC were 1.491 and 1.760mg/g, respectively.",
Arsenic,2088590,"Arsenite Binding to Natural Organic Matter: Spectroscopic Evidence for Ligand Exchange and Ternary Complex Formation Abstract: The speciation of As in wetlands is often controlled by natural organic matter (NOM), which can form strong complexes with Fe(III). Here, we elucidated the molecular-scale interaction of arsenite (As(III)) with Fe(III)-NOM complexes under reducing conditions. We reacted peat (40-250 ?m size fraction, 1.0 g Fe/kg) with 0-15 g Fe/kg at pH &lt;2, removed nonreacted Fe, and subsequently equilibrated the Fe(III) complexes formed with 900 mg As/kg peat at pH 7.0, 8.4, and 8.8. The solid-phase speciation of Fe and As was studied by electron paramagnetic resonance (Fe) and X-ray absorption spectroscopy (As, Fe). Our results show that the majority of Fe in the peat was present as mononuclear Fe(III) species (RFe-C = 2.82-2.88 Å), probably accompanied by small Fe(III) clusters of low nuclearity (RFe-Fe = 3.25-3.46 Å) at high pH and elevated Fe contents. The amount of As(III) retained by the original peat was 161 mg As/kg, which increased by up to 250% at pH 8.8 and an Fe loading of 7.3 g/kg. With increasing Fe content of peat, As(III) increasingly formed bidentate mononuclear (RAs-Fe = 2.88-2.94 Å) and monodentate binuclear (RAs-Fe = 3.35-3.41 Å) complexes with Fe, thus yielding direct evidence of ternary complex formation. The ternary complex formation went along with a ligand exchange reaction between As(III) and hydroxylic/phenolic groups of the peat (RAs-C = 2.70-2.77 Å). Our findings thus provide spectroscopic evidence for two yet unconfirmed As(III)-NOM interaction mechanisms, which may play a vital role in the cycling of As in sub- and anoxic NOM-rich environments such as peatlands, peaty sediments, swamps, or rice paddies.",
Arsenic,1019712,"Occupational arsenic exposure and glycosylated haemoglobin Abstract: In a group of 40 workers occupationally exposed to arsenic (As workers) biological markers for cardiovascular diseases were studied. The median arsenic concentration in urine samples from the exposed group was 22.3 nmol of As per mmol of creatinine, while the individual maximum level was 294.5 nmol of As per mmol of creatinine. That of the reference group was 12 nmol of As per mmol of creatinine and significantly below the level of the exposed group (p &lt; 0.001). The arsenic concentration in urine samples from colleagues of the persons working with arsenic containing products was similar to the arsenic concentration in urine samples from the As workers. The concentration of glycosylated haemoglobin (Hgb A1C) was increased in whole blood from the As workers. The level of the As workers was 5.4% (median), similar to that of colleagues (5.5%), while that of the reference group was 4.4%. The differences were significant (p &lt; 0.001). Multiple regression analysis showed a significant connection (p = 0.034) between the concentration of Hgb A1C in whole blood and the arsenic level in urine from the As workers. The systolic blood pressure was 125 mm Hg in the As workers and 117 mm Hg in the control group. The difference was significant (p = 0.023). It is concluded that arsenic exposure has an influence on carbohydrate metabolism, increases the systolic blood pressure and finally may result in increased risk of development of cardiovascular diseases.",
Arsenic,15842,"Generation of cyclic guanosine monophosphate by heme oxygenases in the human testis--a regulatory role for carbon monoxide in Sertoli cells? Abstract: #Previous studies have demonstrated that cGMP is produced by nitric oxide-mediated activation of soluble guanylyl cyclase (sGC) in seminiferous tubules of the human testis. It is not known, however, whether carbon monoxide (CO), another activator of sGC, is also involved in testicular function. To address this issue, testicular probes from 65- to 75-yr-old men have been examined. The CO-generating enzyme, heme oxygenase-1 (HO-1), could be localized by immunohistochemical and immunoblot analyses to Sertoli cells. In these cells, HO-1 is detectable in adluminal cell compartments, whereas sGC immunoreactivity is distributed exclusively in basal compartments. Treatments of isolated tubules with either sodium arsenite, known to induce HO-1, or hematin, an HO substrate, resulted in 4.4- and 1.8-fold, respectively, increases in cGMP levels. ODQ, a specific sGC inhibitor, inhibited completely the sodium arsenite-stimulated cGMP production. Moreover, the HO inhibitor zinc protoporphyrin-IX and the CO scavenger hemoglobin both significantly reduced (77% or 46% of control, respectively) tubular cGMP generation. These findings, demonstrating for the first time a link between HO-1 activity in Sertoli cells and sGC-dependent cGMP production in seminiferous tubules, suggest a functional role of CO in the human testis.",
Arsenic,1579307,"Decontamination of spent iron-oxide coated sand from filters used in arsenic removal Abstract: Sand filters devised with iron-rich adsorbents are extensively promoted and deployed in the arsenic-prone south and south-east Asian countries (e.g., Bangladesh). The approach offers superior performance in removing arsenic while the spent sludge from the sand filters is an issue of concern due to the possibility of toxic releases after being discarded. In this work, a new technique is proposed for the treatment of spent iron-oxide coated sand (IOCS) from filters used in arsenic removal. Chelant-washing of the arsenic-loaded IOCS is combined with the solid phase extraction treatment to accomplish the objective. The unique point of the proposed process is the cost-effective scheme, which includes the option of recycling of the washing solvent beside the decontamination of the spent arsenic-rich sludge.",
Arsenic,1252316,"Dimethylarsinic acid induces 8-hydroxy-2'-deoxyguanosine formation in the kidney of NCI-Black-Reiter rats Abstract: Dirnethylarsenic peroxyl radical [(CH(3))(2)AsOO] has been postulated to be responsible for DNA damage induced by dimethylarsinic acid (DMA). In an effort to elucidate the possible mechanism of tumor-inducing potential of DMA, an experiment was designed to investigate the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a specific marker of oxidative base damage in the kidney tissues of NCI-Black Reiter (NBR) rats. Animals were divided into four groups and administered the vehicle - saline, 5, 10 and 20 mg/kg body weight respectively of DMA by gavage, once a day, 5 days a week, for a period of 4 weeks. DMA induced increase of 8-OHdG levels in the kidney of the rats treated, with the highest level at the dose of 10 mg/kg body weight. Analysis of the kidney for cell proliferation employing PCNA-positive index showed greater proliferation in the tissues of treated rats. However, DMA did not have any influence on apoptosis in this regimen. Histopathological examination of the kidney selections revealed the presence of vacuolated degeneration and dilation of the proximal tubule cells in two groups (10 and 20 mg/kg body weight). This study provides evidence to substantiate the role of DMA in inducing oxidative DNA damage in the kidney.",
Arsenic,1351738,"Evaluation of monosodium methane arsenate for the suppression of native elm bark beetles, Hylurgopinus rufipes (Eichhoff) (Coleoptera: Scolytidae) Abstract: The native elm bark beetle, Hylurgopinus rufipes (Eichhoff), is the major vector of Dutch elm disease, Ophiostoma ulmi (Buisman) Nannf., in Manitoba. The herbicide Glowon™, monosodium methane arsenate (MSMA), was applied to a chainsaw cut in American elm, Ulmus americana L., tree stems to determine if the treated elms would become effective trap trees for H. rufipes. Three treatments were compared: treated with herbicide and girdled, girdled, and control. All herbicide-treated elms died within 18 days after application. Significantly higher numbers (P < 0.01) of native elm bark beetles were attracted to the herbicided elms, compared with the other treatments. Beetles bred only in the elms treated with herbicide. Of the total brood galleries constructed, 72% had no egg hatch while the remaining 28% had larval tunnels. Progeny adults emerged from less than 1% of the larval tunnels. MSMA application could supplement the Dutch elm disease management program in Manitoba.",
Arsenic,820,"Arsenic content of homeopathic medicines Abstract: In order to test the widely held assumption that homeopathic medicines contain negligible quantities of their major ingredients, six such medicines labeled in Latin as containing arsenic were purchased over the counter and by mail order and their arsenic contents measured. Values determined were similar to those expected from label information in only two of six and were markedly at variance in the remaining four. Arsenic was present in notable quantities in two preparations. Most sales personnel interviewed could not identify arsenic as being an ingredient in these preparations and were therefore incapable of warning the general public of possible dangers from ingestion. No such warnings appeared on the labels.",
Arsenic,1020744,"A proteome analysis of the arsenite response in cultured lung cells: evidence for in vitro oxidative stress-induced apoptosis Abstract: Arsenite is well documented as a chemotherapeutic agent capable of inducing cell death. However, the cellular response at the molecular level has not been studied extensively. In the present study, we provide for the first time a proteomic analysis of rat LECs (lung epithelial cells) treated with arsenite, with the aim of identifying defence proteins, probably expressed to protect the cells during the course of arsenic-induced apoptosis. Comparative proteome analysis was conducted on LECs and LECs treated with 40 microM arsenite to identify global changes in their protein expression profiles. Over 1000 protein spots were separated by two-dimensional electrophoresis and visualized by silver staining. Seven proteins changed expression levels significantly and were identified by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry and database searching. The proteins up-regulated were mostly HSPs (heat-shock proteins) and antioxidative stress proteins, including HSP70, aldose reductase, haem oxygenase-1, HSP27, ferritin light chain and alphaB-crystallin. The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase was down-regulated. Pretreatment with the thiol antioxidants glutathione or N-acetylcysteine before arsenite insult effectively abrogated the induction of these defence proteins and sustained cell viability, whereas antioxidants were protective only at earlier time points if they were added to cells after arsenite. Taken together, our results demonstrate that high levels of arsenite cause oxidative stress-induced apoptosis.",
Arsenic,1017766,"Health benefits of 'grow your own' food in urban areas: implications for contaminated land risk assessment and risk management? Abstract: Compelling evidence of major health benefits of fruit and vegetable consumption, physical activity, and outdoor interaction with 'greenspace' have emerged in the past decade - all of which combine to give major potential health benefits from 'grow-your-own' (GYO) in urban areas. However, neither current risk assessment models nor risk management strategies for GYO in allotments and gardens give any consideration to these health benefits, despite their potential often to more than fully compensate the risks. Although urban environments are more contaminated by heavy metals, arsenic, polyaromatic hydrocarbons and dioxins than most rural agricultural areas, evidence is lacking for adverse health outcomes of GYO in UK urban areas. Rarely do pollutants in GYO food exceed statutory limits set for commercial food, and few people obtain the majority of their food from GYO. In the UK, soil contamination thresholds triggering closure or remediation of allotment and garden sites are based on precautionary principles, generating 'scares' that may negatively impact public health disproportionately to the actual health risks of exposure to toxins through own-grown food. By contrast, the health benefits of GYO are a direct counterpoint to the escalating public health crisis of 'obesity and sloth' caused by eating an excess of saturated fats, inadequate consumption of fresh fruit and vegetables combined with a lack of exercise. These are now amongst the most important preventable causes of illness and death. The health and wider societal benefits of 'grow-your-own' thus reveal a major limitation in current risk assessment methodologies which, in only considering risks, are unable to predict whether GYO on particular sites will, overall, have positive, negative, or no net effects on human health. This highlights a more general need for a new generation of risk assessment tools that also predict overall consequences for health to more effectively guide risk management in our increasingly risk-averse culture.",
Arsenic,594587,"Disruption of microtubule assembly and spindle formation as a mechanism for the induction of aneuploid cells by sodium arsenite and vanadium pentoxide Abstract: Arsenic and vanadium are important environmental and industrial pollutants. Due to their widespread occurrence and potential genotoxicity, we studied the aneuploidy-inducing effects of these elements in cultured human lymphocytes using a variety of techniques including fluorescence in situ hybridization (FISH) with DNA probes for chromosomes 1 and 7, immunostaining of the lymphocyte spindle apparatus, and an in vitro assay measuring the polymerization and depolymerization of tubulin. Dose-related increases in hyperdiploidy were seen in lymphocyte cultures treated with sodium arsenite (NaAsO2) or vanadium pentoxide (V2O5) over concentrations ranging from 0.001 to 0.1 microM. NaAsO2-treated cells from different donors exhibited similar hyperdiploid frequencies, whereas substantial inter-individual variability was seen in the V2O5-treated cells. Examination of the spindle apparatus using an anti-beta-tubulin antibody indicated that these compounds might disrupt spindle formation by interacting with microtubules. Additional in vitro assays using purified tubulin indicated that both compounds inhibited microtubule assembly and induced tubulin depolymerization. These results indicate that in vitro exposure to both NaAsO2 and V2O5 can induce aneuploidy in human lymphocytes, and that this effect may occur through a disruption of microtubule function.",
Arsenic,1597444,"DNA sequence variation and methylation in an arsenic tolerant earthworm population Abstract: Evidence is emerging that earthworms can evolve tolerance to trace element enriched soils. However, few studies have sought to establish whether such tolerance is determined through adaptation or plasticity. Here we report results from a combined analysis of mitochondrial (cytochrome oxidase II, COII), nuclear (amplified fragment length polymorphism, AFLP) variation and DNA methylation in populations of the earthworm Lumbricus rubellus from sites across an abandoned arsenic and copper mine. Earthworms from the mine site population demonstrated clear arsenic tolerance in comparison to a naïve strain. COII and AFLP results suggest that L. rubellus from the unexposed and the adapted populations comprises two cryptic lineages (Lineages A and B) each of which was present across all of the sites. AFLP analysis by lineage highlighted variations associated with soil metal/metalloid concentrations (most clearly for Lineage A) suggesting a genetic component to the observed tolerance. The methylation sensitive AFLP (Me-AFLP) identified a high genome methylation content (average 13.5%) in both lineages. For Lineage A, Me-AFLP analysis did not identify a strong association with soil arsenic levels. For Lineage B, however, a clear association of methylation patterns with soil arsenic concentrations was found. This suggests that Lineage B earthworms utilise epigenetic mechanisms to adapt to the presence of contamination. These fundamentally different genetic adjustments in the two clades indicate that the two lineages employ distinct adaptive strategies (genetic or epigenetic) in response to arsenic exposure. Mechanisms driving this variation may be founded within the colonisation histories of the lineages.",
Arsenic,1348037,"Expression of the putative tumor suppressor gene PTPN13/PTPL1 is an independent prognostic marker for overall survival in breast cancer Abstract: Although it is well established that some protein tyrosine kinases have a prognostic value in breast cancer, the involvement of protein tyrosine phosphatases (PTPs) is poorly substantiated for breast tumors. Three of these enzymes (PTP-gamma, LAR, and PTPL1) are already known to be regulated by estrogens or their antagonists in human breast cancer cells. We used a real-time reverse transcriptase polymerase chain reaction method to test the expression levels of PTP-gamma, LAR and its neuronal isoform, and PTPL1 in a training set of RNA from 59 breast tumors. We sought correlations between levels of these molecular markers, current tumor markers, and survival. We then quantified the expression level of the selected phosphatase in 232 additional samples, resulting in a testing set of 291 breast tumor RNAs from patients with a median follow-up of 6.4 years. The Spearman nonparametric test revealed correlations between PTPL1 expression and differentiation markers. Cox univariate analysis of the overall survival studies demonstrated that PTPL1 is a prognostic factor [risk ratio (RR)=0.45], together with the progesterone receptor (PR) (RR=0.52) and node involvement (RR=1.58). In multivariate analyses, PTPL1 and PR retained their prognostic value (RRs of 0.48 and 0.55, respectively). This study demonstrates for the first time that PTPL1 expression level is an independent prognostic indicator of favorable outcome for patients with breast cancer. In conjunction with our mechanistic studies, this finding identifies PTPL1 as an important regulatory element of human breast tumor aggressiveness and sensitivity to treatments such as antiestrogens and antiaromatase.",
Arsenic,1021544,"Toxicological Characterization of the Inorganic and Organic Arsenic Metabolite Thio-DMA in Cultured Human Lung Cells Abstract: We synthesised and toxicologically characterised the arsenic metabolite thiodimethylarsinic acid (thio-DMA(V)). Successful synthesis of highly pure thio-DMA(V) was confirmed by state-of-the-art analytical techniques including (1)H-NMR, HPLC-FTMS, and HPLC-ICPMS. Toxicological characterization was carried out in comparison to arsenite and its well-known trivalent and pentavalent methylated metabolites. It comprised cellular bioavailability as well as different cytotoxicity and genotoxicity end points in cultured human A549 lung cells. Of all arsenicals investigated, thio-DMA(V) exerted the strongest cytotoxicity. Moreover, thio-DMA(V) did not induce DNA strand breaks and an increased induction of both micronuclei and multinucleated cells occurred only at beginning cytotoxic concentrations, indicating that thio-DMA(V) does not act via a genotoxic mode of action. Finally, to assess potential implications of thio-DMA(V) for human health, further mechanistic studies are urgently necessary to identify the toxic mode of action of this highly toxic, unusual pentavalent organic arsenical.",
Arsenic,1017566,"Development of a microfluidics biosensor for agarose-bead immobilized Escherichia coli bioreporter cells for arsenite detection in aqueous samples Abstract: Contamination with arsenic is a recurring problem in both industrialized and developing countries. Drinking water supplies for large populations can have concentrations much higher than the permissible levels (for most European countries and the United States, 10 ?g As per L; elsewhere, 50 ?g As per L). Arsenic analysis requires high-end instruments, which are largely unavailable in developing countries. Bioassays based on genetically engineered bacteria have been proposed as suitable alternatives but such tests would profit from better standardization and direct incorporation into sensing devices. The goal of this work was to develop and test microfluidic devices in which bacterial bioreporters could be embedded, exposed and reporter signals detected, as a further step towards a complete miniaturized bacterial biosensor. The signal element in the biosensor is a nonpathogenic laboratory strain of Escherichia coli, which produces a variant of the green fluorescent protein after contact to arsenite and arsenate. E. coli bioreporter cells were encapsulated in agarose beads and incorporated into a microfluidic device where they were captured in 500 × 500 ?m(2) cages and exposed to aqueous samples containing arsenic. Cell-beads frozen at -20 °C in the microfluidic chip retained inducibility for up to a month and arsenic samples with 10 or 50 ?g/L) could be reproducibly discriminated from the blank. In the 0-50 ?g/L range and with an exposure time of 200 minutes, the rate of signal increase was linearly proportional to the arsenic concentration. The time needed to reliably and reproducibly detect a concentration of 50 ?g/L was 75-120 minutes, and 120-180 minutes for a concentration of 10 ?g/L.",
Arsenic,1025413,"Tissue uptake, mortality, and sublethal effects of monomethylarsonic acid (MMA(V)) in nestling zebra finches (Taeniopygia guttata) Abstract: Monosodium methanearsonate (MSMA), an arsenic-based pesticide, has been used since the mid 1980s in attempts to suppress mountain pine beetle (Dendroctonus ponderosae) outbreaks in British Columbia, Canada. It was previously shown that cavity nesting forest birds forage and breed in MSMA-treated pine stands. The present study was designed to investigate the effects of ecologically relevant oral exposure to MSMA, including tissue distribution, growth parameters, and general health, including survival and immune function, of a model passerine, the zebra finch (Taeniopygia guttata). Nestling finches were orally dosed for 20 d from hatching to fledging with 4, 8, 12, 24, 36, or 72 microg/g bw/d of monomethylarsonic acid (MMA(V), which corresponds to MSMA at physiological pH). Preliminary trials showed complete mortality at 36 and 72 microg/g bw/d, and repeat trials also resulted in high mortality at 24 microg/g bw/d. Surviving nestlings showed dose-dependent trends in accumulation of arsenic in blood and specific tissues, and decreased tarsi and wing cord length upon fledging. There were no observed effects of dosing on measured immune function (phytohemagglutinin [PHA], hematocrit, and leukocrit). The data obtained suggest that passerine nestlings may be at risk of mortality and reduced growth due to exposure to MSMA under current environmental conditions.",
Arsenic,1346612,"Effect of DNA hypomethylation on genotoxicity and apoptogenicity of sodium arsenite in laboratory mice Abstract: The present study aims to evaluate the effect of DNA hypomethylation state on genotoxicity and apoptogenicity induced by sodium arsenite (NaAsO2) in normal adult male SWR/J mouse bone marrow cells. Animals were treated with intraperitoneally (i.p.) injected with (2.25, 4.50 or 9 mg kg(-1) b.wt. of NaAsO2 which represent 0.25, 0.50 or 1 of LD5, respectively) and killed 24 h later. Another different group of male mice was treated with three doses of 5-Azacitidine (5-AzaC), 5 mg kg(-1) b.wt. each dose and 3 h intervals between them. NaAsO2 administered after 6 days of the last dose. The three single doses of sodium arsenite alone significantly (p&lt;0.05) increased the rate of total structural Chromosomal Aberrations (CAs), rate of Sister Chromatid Exchanges (SCEs), micronucleus (MNs) formation, PARP and Lamia-A degradation and apoptosis as compared with the negative control. The combined treatment with hypomethylation agent 5-AzaC significantly increased the rate of SCEs induced by NaAsO2 at low dose. Moreover, this treatment significantly increased the rate of polyploidy at all combined used doses. Furthermore, this treatment induced apoptosis at all used doses. The present study has shown that DNA hypomethylation had a negative effects represented in rate of (CAs), polyploidy, PARP degradation and apoptosis induced by (NaAsO2). On the other hand, DNA hypomethylation had positive effects represented in decreas rate of pulverized chromosomes, centromeric attenuations, (SCEs), (MNs) formation, prevent Lamina-A degradation and apoptosis.",1
Arsenic,628338,"Arsenic in drinking water and adverse pregnancy outcome in an arseniasis-endemic area in northeastern Taiwan Abstract: The well water in Lanyang Basin, which is located in the northeastern portion of Taiwan island, was found to have high levels of arsenic ranging from undetectable levels (<0.15 ppb) to 3.59 ppm. We performed a study to compare the risk of adverse pregnancy outcomes (preterm delivery and birthweight) between an area with historic high well water arsenic levels (arsenic-exposed area (AE)) and a comparison area with no historic evidence of arsenic water contamination (non-arsenic-exposed area (NAE)). The mean birth weight in the AEs and NAEs were 3132.6 and 3162.6 g, respectively. Babies born in AEs were on average 30 g lighter than those born in NAEs. AEs had a higher rate of preterm delivery than NAEs (3.74% vs 3.43%). The results of this study suggest that, after adjustment for potential confounders, arsenic exposure from drinking well water was associated, although not significantly, with the risk of preterm delivery, with an odds ratio of 1.10 (0.91-1.33). The estimated reduction in birth weight was 29.05 g (95% CI=13.55-44.55). The findings from this investigation provide evidence for a potential role for arsenic exposure through drinking water in increasing the risk of low birthweight.",
Arsenic,2149353,Genesis of arsenic enriched groundwater and relationship with bedrock geology in northern Sweden Abstract: ,
Arsenic,1021250,"Arsenite sensitizes human melanomas to apoptosis via tumor necrosis factor alpha-mediated pathway Abstract: Arsenic is a well established human carcinogen and is associated with a variety of cancers including those of the skin. Paradoxically, arsenic has also been used, amid at low doses, in the treatment of leukemia for over a century. Here we demonstrate that low to moderate concentrations of arsenite (2-10 microm) that has little or no effect on normal melanocytes may induce apoptosis of human melanomas including highly metastatic ones despite their low surface Fas levels. The two prerequisites that dictate apoptotic response of melanomas upon arsenite treatment are low nuclear NF-kappaB activity and an endogenous expression of tumor necrosis factor alpha. Under these conditions, melanoma cells acquired sensitivity to tumor necrosis factor alpha-mediated killing. On the other hand, signaling pathways including those of phosphatidylinositol 3-kinase-AKT, MEK-ERK, and JNK play a protective role against arsenite-induced oxidative stress and apoptosis in melanoma cells. Suppression of these pathways dramatically accelerates arsenite-induced apoptosis. Taken together, these data could provide potential approaches to sensitize melanomas to the cytotoxic effects of arsenite through modulating the signaling pathways.",
Arsenic,1246944,"Arsenic decreases RXR alpha-dependent transcription of CYP3A and suppresses immune regulators in hepatocytes Abstract: Arsenite is critical pharmacologically as a treatment for advanced stage blood cancer. However, environmental exposure to arsenic results in multiple diseases. Previous studies have shown that arsenic decreases expression of CYP3A, a critical drug metabolizing enzyme in human and rat liver. In addition, acute and chronic arsenic exposure in liver stimulates an inflammatory response. Our work has shown that arsenite decreases nuclear levels of RXR? the nuclear receptor that, as a heterodimer partner with PXR, transactivates the CYP3A gene. These results suggest that arsenite decreases transcription of CYP3A by decreasing RXR?. The present report shows that exposure to 5 ?M arsenite decreased the activity of a rat CYP3A promoter luciferase reporter in HepG2 cells. The activity of a RARE-luciferase reporter, that is transactivated by the retinoic acid receptor (RAR)/RXR?, was also decreased. Previous studies have shown that arsenic in the concentration range of 2-5 ?M affects CYP3A mRNA. When rifampicin-treated primary human hepatocyte cultures were exposed to arsenite concentrations as low as 50 nM, CYP3A mRNA was decreased. Treatment of primary human hepatocytes with the proteasome inhibitor MG132 increased RXR? suggesting the involvement of the proteasome pathway in regulation of RXR?. Finally, arsenic induces a pro-inflammatory response in liver. Surprisingly, we show that in hepatocytes arsenite decreases expression of two inflammatory mediators, TNF and VEGF, an effect that is not predicted from suppression of RXR? activity.",
Arsenic,1016008,"Co-administration of meso 2,3-dimercaptosuccinic acid monoesters reduces arsenic concentration and oxidative stress in gallium arsenide exposed rats Abstract: 1. Gallium arsenide (GaAs), a semiconductor, exerts toxicity as a result of its constitutive moieties; that is, gallium and arsenic that becomes dissociated after exposure. The present study focuses on reducing arsenic concentration from the target organs using monoesters of meso 2,3-dimercaptosuccinic acid (DMSA) either individually or in combination. 2. Animals were exposed to GaAs (0.0014 mol/kg, orally for 8 weeks) and then treated with monoisoamyl DMSA (MiADMSA), monocyclohexyl DMSA (MchDMSA) or monomethyl DMSA (MmDMSA) either individually (0.3 mmol/kg, orally) or in combination (0.15 mmol/kg each, orally) for five consecutive days. 3. GaAs exposure significantly inhibited blood ?-aminolevulinic acid dehydrogenase (ALAD), suggesting alterations in the heme synthesis pathway. Whereas a significant increase in blood, liver and kidney reactive oxygen species accompanied by an increase in lipid peroxidation points to the involvement of oxidative stress in GaAs toxicity. 4. GaAs also significantly disturbed glutathione metabolism. Hepatic and renal catalase activity decreased significantly, whereas hepatic and renal superoxide dismutase activity, as well as serum transaminases activity, showed marginal increase. Treatment with MiADMSA in combination with MchDMSA showed better therapeutic efficacy compared with other treatments in the aforementioned variables. 5. Co-administration of MiADMSA with MchDMSA provided better therapeutic effects, including reduction of arsenic burden, compared with all other treatments.",
Arsenic,1509358,"Phosphate amendment of metalliferous tailings, Cannington Ag-Pb-Zn mine, Australia: Implications for the capping of tailings storage facilities Abstract: This study appraised the use of phosphate fertilisers in immobilising metals in mine tailings to prevent their uptake into Curly Mitchell grass (Astrebla lappacea), when grown on capped, phosphate-amended tailings. Leaching experiments showed that Pb mobility was reduced by both bone meal and superphosphate amendment. Bone meal amendment also reduced Cd mobility. By contrast, Cd, Mn and Zn mobility increased in superphosphate-amended tailings due to increased acid production and, Cu was mobilised in bone meal-amended tailings possibly through the formation of soluble metal-complexing organic compounds. Arsenic and Sb were mobilised in both treatments due to phosphate ligand exchange. Greenhouse trials used Curly Mitchell grass grown on 1-m-high columns stacked with waste materials and different amendments overlain by clean topsoil. Curly Mitchell grass showed substantial uptake of Cd, Mn, Pb and Zn from unamended tailings and waste rock, where these were penetrated by the plant’s root system. Addition of phosphate fertilisers to the surface of tailings did not result in reduced metal uptake by Curly Mitchell grass. In tailings capped with limestone, the limestone layer formed an effective physical barrier preventing root penetration into the tailings and led to substantially reduced metal uptake in grass. The study demonstrates that thorough mixing of waste materials and fertilisers as well as irrigation may be required for successful phosphate immobilisation of metals in base metal tailings. Alternatively, the placement of a thin layer of crushed limestone on top of the tailings pile prior to capping may lead to the formation of a chemical and physical barrier and prevent the transfer of environmentally significant elements into the above-ground biomass of Mitchell grasses.",
Arsenic,1352492,"The oxidative stressor arsenite activates vascular endothelial growth factor mRNA transcription by an ATF4-dependent mechanism Abstract: Aberrant retinal expression of vascular endothelial growth factor (VEGF) leading to neovascularization is a central feature of age-related macular degeneration and diabetic retinopathy, two leading causes of vision loss. Oxidative stress is suggested to occur in retinal tissue during age-related macular degeneration and diabetic retinopathy and is suspected in the mechanism of VEGF expression in these diseases. Arsenite, a thiol-reactive oxidative stressor, induces VEGF expression by a HIF-1alpha-independent mechanism. Previously, we demonstrated that homocysteine, an endoplasmic reticulum stressor, increases VEGF transcription by a mechanism dependent upon activating transcription factor ATF4. Because ATF4 is expressed in response to oxidative stress, we hypothesized that ATF4 was also responsible for increased VEGF transcription in response to arsenite. We now show that arsenite increased steady state levels of VEGF mRNA and activated transcription from a VEGF promoter construct. Arsenite induced eIF2alpha phosphorylation, resulting in increased ATF4 protein levels. Inactivation or loss of ATF4 greatly diminished the VEGF response to arsenite treatment. Overexpression of ATF4 was sufficient to activate the VEGF promoter, and arsenite cooperated with exogenous ATF4 to further activate the promoter. A complex containing ATF4 binds a DNA element at +1767 bp relative to the VEGF transcription start site, and DNA binding activity is increased by arsenite treatment. In addition, the ability of a thiol antioxidant, N-acetylcysteine, to inhibit the effect of arsenite on VEGF expression coincided with its ability to inhibit phosphorylation of eIF2alpha and ATF4 protein expression. Thus, arsenite-induced up-regulation of VEGF gene transcription occurs by an ATF4-dependent mechanism.",
Arsenic,1033470,"The arsenic content of human semen Abstract: Arsenic concentration was measured by atomic absorption spectrometer in ejaculates of 13 subfertile men, 6 control individuals and pool-ejaculate of 24 further andrological patients. While the detection limit was 1 microgram/l, arsenic concentration amounted to 2 micrograms AS/l in ejaculates. In the cellular fractions of seminal fluid, concentration of arsenic was under the detection limit. Arsenic concentration of smokers and non-smokers did not differ.",
Arsenic,2088555,"Death receptor 6 (DR6) antagonist antibody is neuroprotective in the mouse SOD1(G93A) model of amyotrophic lateral sclerosis Abstract: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the death of motor neurons, axon degeneration, and denervation of neuromuscular junctions (NMJ). Here we show that death receptor 6 (DR6) levels are elevated in spinal cords from post-mortem samples of human ALS and from SOD1(G93A) transgenic mice, and DR6 promotes motor neuron death through activation of the caspase 3 signaling pathway. Blocking DR6 with antagonist antibody 5D10 promotes motor neuron survival in vitro via activation of Akt phosphorylation and inhibition of the caspase 3 signaling pathway, after growth factor withdrawal, sodium arsenite treatment or co-culture with SOD1(G93A) astrocytes. Treatment of SOD1(G93A) mice at an asymptomatic stage starting on the age of 42 days with 5D10 protects NMJ from denervation, decreases gliosis, increases survival of motor neurons and CC1(+) oligodendrocytes in spinal cord, decreases phosphorylated neurofilament heavy chain (pNfH) levels in serum, and promotes motor functional improvement assessed by increased grip strength. The combined data provide clear evidence for neuroprotective effects of 5D10. Blocking DR6 function represents a new approach for the treatment of neurodegenerative disorders involving motor neuron death and axon degeneration, such as ALS.",
Arsenic,2149177,"Rapid impact of phenanthrene and arsenic on bacterial community structure and activities in sand batches Abstract: The impact of both organic and inorganic pollution on the structure of soil microbial communities is poorly documented. A short-time batch experiment (6 days) was conducted to study the impact of both types of pollutants on the taxonomic, metabolic and functional diversity of soil bacteria. For this purpose sand spiked with phenanthrene (500 mg kg(-1) sand) or arsenic (arsenite 0.66 mM and arsenate 12.5 mM) was supplemented with artificial root exudates and was inoculated with bacteria originated from an aged PAH and heavy-metal-polluted soil. The bacterial community was characterised using bacterial strain isolation, TTGE fingerprinting and proteomics. Without pollutant, or with phenanthrene or arsenic, there were no significant differences in the abundance of bacteria and the communities were dominated by Pseudomonas and Paenibacillus genera. However, at the concentrations used, both phenanthrene or arsenic were toxic as shown by the decrease in mineralisation activities. Using community-level physiological profiles (Biolog Ecoplates™) or differential proteomics, we observed that the pollutants had an impact on the community physiology, in particular phenanthrene induced a general cellular stress response with changes in the central metabolism and membrane protein synthesis. Real-time PCR quantification of functional genes and transcripts revealed that arsenic induced the transcription of functional arsenic resistance and speciation genes (arsB, ACR3 and aioA), while no transcription of PAH-degradation genes (PAH-dioxygenase and catechol-dioxygenase) was detected with phenanthrene. Altogether, in our tested conditions, pollutants do not have a major effect on community abundance or taxonomic composition but rather have an impact on metabolic and functional bacterial properties.",
Arsenic,78137,"Possible role of oxidative damage in metal-induced carcinogenesis Abstract: BIOSIS COPYRIGHT: BIOL ABS. This review presents and evaluates evidence relevant to the mechanisms of metal carcinogenicity with special emphasis on the emerging hypothesis of the oxidative nature of metals' effect on DNA. The carcinogenic transition metals are capable of in vivo binding with the cell nucleus and causing promutagenic damage that includes DNA base modifications, inter- and intramolecular crosslnking of DNA and proteins, DNA strand breaks, rearrangements, and depurination. The chemistry of that damage and the resulting mutations observed in vitro and in metal-induced tumors are both characteristic for oxidative attack on DNA. The underlying mechanism involves various kinds of active oxygen and other radical species arising from metal-catalyzed redox reactions of O2, J2O2, lipid peroxides, and others, with certain amino acids, peptides, and proteins. Other metal-mediated pathogenic effects, such as enhancement of lipid peroxidation, stimulation of inflammation, inhibition of cellular",
Arsenic,1018368,"Comparative and environmental genotoxicity of antimony and arsenic Abstract: Antimony and arsenic compounds are known to have a genotoxic potential. Soil contamination with these elements can be due to the presence of natural ore sources of fahlore (gray copper). As a result, human and animal populations may be highly exposed. The sister chromatid exchange (SCE) test is an adequate tool for the sensitive detection of antimony and arsenic genotoxicity. We used this assay to investigate the coergism of the two elements in vitro to gain data for the assessment of a putative risk from coexposure. The combinative effect of antimony and arsenic in the SCE test appeared subadditive. Additionally, the SCE served to determine the genotoxic potential in extracts of contaminated fahlore soil samples gained under mildly acidic conditions. The genotoxicity observed was very low because antimony and arsenic predominated in the pentavalent, non-genotoxic state, but, the partial antagonism observed in the in vitro experiments could be an additional explanation for the low genotoxicity.",
Arsenic,1025948,"Biologically based modeling of multimedia, multipathway, multiroute population exposures to arsenic Abstract: This article presents an integrated, biologically based, source-to-dose assessment framework for modeling multimedia/multipathway/multiroute exposures to arsenic. Case studies demonstrating this framework are presented for three US counties (Hunderton County, NJ; Pima County, AZ; and Franklin County, OH), representing substantially different conditions of exposure. The approach taken utilizes the Modeling ENvironment for TOtal Risk studies (MENTOR) in an implementation that incorporates and extends the approach pioneered by Stochastic Human Exposure and Dose Simulation (SHEDS), in conjunction with a number of available databases, including NATA, NHEXAS, CSFII, and CHAD, and extends modeling techniques that have been developed in recent years. Model results indicate that, in most cases, the food intake pathway is the dominant contributor to total exposure and dose to arsenic. Model predictions are evaluated qualitatively by comparing distributions of predicted total arsenic amounts in urine with those derived using biomarker measurements from the NHEXAS--Region V study: the population distributions of urinary total arsenic levels calculated through MENTOR and from the NHEXAS measurements are in general qualitative agreement. Observed differences are due to various factors, such as interindividual variation in arsenic metabolism in humans, that are not fully accounted for in the current model implementation but can be incorporated in the future, in the open framework of MENTOR. The present study demonstrates that integrated source-to-dose modeling for arsenic can not only provide estimates of the relative contributions of multipathway exposure routes to the total exposure estimates, but can also estimate internal target tissue doses for speciated organic and inorganic arsenic, which can eventually be used to improve evaluation of health risks associated with exposures to arsenic from multiple sources, routes, and pathways.",
Arsenic,2345608,"Localised flux maxima of arsenic, lead, and iron around root apices in flooded lowland rice Abstract: In wetland adapted plants such as rice it is typically root apices, sites of rapid entry for water/nutrients, where radial oxygen losses (ROL) are highest. Nutrient/toxic metal uptake therefore largely occur through oxidized zones and pH micro-gradients. Yet, the processes controlling the acquisition of trace elements in rice have been difficult to explore experimentally due to a lack of techniques for simultaneously measuring labile trace-elements and oxygen/pH. Here we use new diffusive gradients in thin-film (DGT)/planar optode sandwich sensors deployed in situ on rice roots to demonstrate a new geochemical niche of greatly enhanced As, Pb and Fe(II) mobilization into solution immediately adjacent to the root tips characterized by O2 enrichment and low pH. Fe(II) mobilisation was congruent to that of the peripheral edge of the aerobic root zone, demonstrating that Fe(II) mobilisation maximum only develop in a narrow oxygen range as the oxidation front penetrates the reducing soil. The Fe flux to the DGT resin at the root apices was 3-fold higher than the anaerobic bulk soil and 27-times greater than the aerobic rooting zone. These results provide new evidence for the importance of coupled diffusion and oxidation of Fe in modulating trace metal solubilization, dispersion and plant uptake.",
Arsenic,533967,"Water arsenic exposure and intellectual function in 6-year-old children in Araihazar, Bangladesh Abstract: BACKGROUND: We recently reported results of a cross-sectional investigation of intellectual function in 10-year-olds in Bangladesh, who had been exposed to arsenic from drinking water in their home wells. OBJECTIVES: We present results of a similar investigation of 301 randomly selected 6-year-olds whose parents participated in our ongoing prospective study of the health effects of As exposure in 12,000 residents of Araihazar, Bangladesh. METHODS: Water As and manganese concentrations of tube wells at each home were obtained by surveying all study region wells. Children and mothers were first visited at home, where the quality of home stimulation was measured, and then seen in our field clinic, where children received a medical examination wherein weight, height, and head circumference were assessed. We assessed children's intellectual function using subtests drawn from the Wechsler Preschool and Primary Scale of Intelligence, version III, by summing weighted items across domains to create Verbal, Performance, Processing Speed, and Full-Scale raw scores. Children provided urine specimens for measuring urinary As and were asked to provide blood samples for blood lead measurements. RESULTS: Exposure to As from drinking water was associated with reduced intellectual function before and after adjusting for water Mn, for blood lead levels, and for sociodemographic features known to contribute to intellectual function. With covariate adjustment, water As remained significantly negatively associated with both Performance and Processing Speed raw scores; associations were less strong than in our previously studied 10-year-olds. CONCLUSION: This second cross-sectional study of As exposure expands our concerns about As neurotoxicity to a younger age group.",
Arsenic,2347641,"Antimony smelting process generating solid wastes and dust: Characterization and leaching behaviors Abstract: A large amount of solid waste has been produced by the antimony smelting process in the &quot;World Capital of Antimony&quot;, Xikuangshan area in China. This study comprehensively investigated the physical and chemical characteristics of the various solid wastes, as well as the leaching behavior of the solid wastes, which included water-quenched slag, arsenic-alkali residue, desulfurized slag and blast furnace dust. These four types of waste were enriched in a variety of heavy metals and metalloids and more specifically with As and Sb levels up to 8.6×10(4) and 3.16×10(5)mg/kg, respectively, in arsenic-alkali residue. For desulfurized slag and water-quenched slag, the leaching concentration of Sb significantly exceeded the acceptable limits during the leaching tests using the toxicity characteristic leaching procedure and the synthetic precipitation leaching procedure. In addition, As leaching in arsenic-alkali residue was extraordinarily hazardous, being three orders of magnitude higher than the regulatory level of As. According to the results of the extraction tests, all the tested wastes were classified as hazardous waste.",
Arsenic,1373187,"Expression Of AS3MT Alters Transcriptional Profiles In Human Urothelial Cells Exposed To Arsenite Abstract: Inorganic arsenic (iAs) is an environmental toxin and human carcinogen. The enzymatic methylation of iAs that is catalyzed by arsenic (+3 oxidation state)-methyltransferase (AS3MT) generates reactive methyl-As intermediates that may contribute to the toxic or carcinogenic effects of iAs. We have shown that clonal human urothelial cells (UROtsa/F35) that express rat AS3MT and methylate iAs are more susceptible to acute toxicity of iAs than parental UROtsa cells that do not express AS3MT and do not methylate iAs. The current work examines genomic changes associated with AS3MT expression and identifies specific categories of genes expressed in UROtsa and UROtsa/F35 cells in response to a 24h exposure to 1 uM or 50 uM iAs. Here, the expression of 21073 genes was assessed using Agilent Human 1A(V2) arrays. ArrayTrack and Ingenuity Software analyses showed that exposure to 1 uM iAs altered expression of 572 genes in UROtsa/F35 cells as compared to 686 in UROtsa cells. Exposure to 50 uM iAs altered 1578 and 2873 genes in UROtsa/F35 and UROtsa cells, respectively. Pathway mapping at 1 uM iAs exposure showed similar responses in both UROtsa and UROtsa/F35 cells; genes involved in cell cycle, maintenance, and growth were altered. However, only UROsa/F35 cells showed altered profiles for genes regulating cell death and DNA repair, which may suggest an enhanced susceptibility to iAs. At 50 uM, signaling and metabolic pathways were altered in both cell lines. However, changes in UROtsa cells indicated enhanced cell cycling with increases in proliferation and cell death whereas, changes in UROtsa/F35 cells were consistent with repression in cell proliferation and survival. These data suggest that AS3MT expression modifies the genomic responses to iAs exposure in UROtsa cells. Further analysis of these responses will help to characterize the role of AS3MT-catalyzed methylation in modulation of iAs toxicity.",
Arsenic,1015681,"Phytotoxicity of Arsenate and Salinity on Early Seedling Growth of Rice (Oryza sativa L.): A Threat to Sustainable Rice Cultivation in South and South-East Asia Abstract: Arsenic (As) contamination is an important environmental consequence in some parts of salinity-affected South (S) and South-East (SE) Asia. In this study, we investigated the individual and combined phytotoxicity of arsenic (As) [arsenate; As(V)] and salinity (NaCl) on early seedling growth (ESG) of saline-tolerant and non-tolerant rice varieties. Germination percentage (GP), germination speed (GS) and vigor index (VI) of both saline-tolerant and non-tolerant rice varieties decreased significantly (p &gt; 0.01) with increasing As(V) and NaCl concentrations. The highest GP (91%) was observed for saline non-tolerant BRRI dhan28 and BRRI dhan49, while the lowest (62%) was for saline-tolerant BRRI dhan47. The ESG parameters, such as weights and relative lengths of plumule and radicle, also decreased significantly (p &lt; 0.01) with increasing As(V) and NaCl concentrations. Relative radicle length was more affected than plumule length by As(V) and NaCl. Although VI of saline-tolerant and non-tolerant rice seedlings showed significant variation (p &lt; 0.05), weights and lengths of plumule and radicle of different rice varieties did not show significant variation for As(V) and NaCl treatments. Results reveal that the combined phytotoxicity of As(V) and NaCl on rice seed germination and ESG are greater than their individual toxicities, and some saline-tolerant rice varieties are more resistant to the combined phytotoxicity of As(V) and NaCl than the saline non-tolerant varieties.",
Arsenic,8448,"Chromosome aberrations in cultured human lymphocytes exposed to trivalent and pentavalent arsenic Abstract: Cultured human lymphocytes were exposed to trivalent (NaASO2) and pentavalent (Na2HAsO4) arsenic in concentrations comparable to the arsenic levels found in the urine of copper smelter workers. Significantly increased frequencies of chromosome aberrations (gaps, chromatid breaks, chromatid exchanges and chromosome breaks) were found after exposure to trivalent but not pentavalent arsenic. This effect was not found when nonstimulated (GO) lymphocytes were exposed to trivalent arsenic and then cultured. The rate of sister chromatid exchanges was also found to be increased after exposure to trivalent arsenic. Thus results suggest that trivalent arsenic is more genotoxic than pentavalent arsenic and that arsenic exerts its effect mainly during cell division.",
Arsenic,1360364,"Emission spectrometric determination of arsenic Abstract: HEEP COPYRIGHT: BIOL ABS. An arsine generator was coupled directly to the excitation plasma, and the generator system was optimized to permit the rapid, quantitative removal of arsenic from an aqueous sample obtained from Morning Glory Pool in Yellowstone National Park, USA. The system offered high sensitivity; the detection capability, which was primarily limited by the reagent blank, was approximately 5 ng. Less than 5 parts per billion of arsenic were determined when a 1-ml sample was used. The sensitivity that was obtained, coupled with the relative simplicity of the instrumentation required, suggested that this method should find widespread application in problems requiring the determination of trace amounts of arsenic.",
Arsenic,176992,"Disminución de la inteligencia en niños y exposición al fl úor y arsénico en el agua potable Abstract: Recent evidence suggests that fluoride (F) and arsenic (As) may adversely affect intelligence quotient (IQ) scores. We explore the association between exposure to F and As in drinking water and intelligence in children. Three rural communities in Mexico with contrasting levels of F and As in drinking water were studied: Moctezuma (F 0.8+/-1.4 mg/L; As 5.8+/-1.3 microg/L); Salitral (F 5.3+/-0.9 mg/L; As 169+/-0.9 microg/L) and 5 de Febrero (F 9.4+/-0.9 mg/L; As 194+/-1.3 microg/L). The final study sample consisted of 132 children from 6 to 10 years old. After controlling for confounders, an inverse association was observed between F in urine and Performance, Verbal, and Full IQ scores (beta values = -13, -15.6, -16.9, respectively). Similar results were observed for F in drinking water (beta values = -6.7, -11.2, -10.2, respectively) and As in drinking water (beta values= -4.30, -6.40, -6.15, respectively). The p-values for all cases were < 0.001. A significant association was observed between As in urine and Full IQ scores (beta = -5.72, p = 0.003). These data suggest that children exposed to either F or As have increased risks of reduced IQ scores.",
Arsenic,1337306,"Bacillus sp. SXB and Pantoea sp. IMH, aerobic As(V)-reducing bacteria isolated from arsenic-contaminated soil Abstract: AIMS: To isolate highly effective aerobic As(V)-reducing bacteria from arsenic(As)-contaminated soils in Northwest China and to identify their dynamic As(V) reduction processes and genomic detoxification mechanisms. METHODS AND RESULTS: Enrichment cultures were performed aerobically in TYEG medium in the presence of As(V). Strain SXB isolated from soil in Shanxi Province, belonging to Bacillus genus, reduced As(V) more effectively under aerobic conditions than under anaerobic conditions. Strain IMH, a strictly aerobic isolate obtained from soil in Inner Mongolia, identified as Pantoea, is reported for the first time to reduce As(V). Both isolates could reduce over 90% As(V) in 36 h under aerobic conditions. Putative gene fragments for the ArsB efflux pump gene were obtained from both strains. The putative arsenate reductase gene was only amplified from strain SXB. A putative arsH gene was amplified from strain IMH. CONCLUSIONS: Strain SXB and IMH isolated from the As-contaminated soils reduce As(V) effectively under aerobic conditions via a detoxification mechanism regulated by ars operons. © 2012The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.",
Arsenic,1519190,"Acute poisoning by monosodium methanearsonic acid in cattle Abstract: Poisoning by monosodium methanearsonic acid (MSMA) is reported in a herd of 24 Girolando cows that were introduced into a pasture sprayed with the herbicide. Clinical signs were apathy, anorexia, and profuse diarrhea. Fourteen cows died and two were necropsied. Abomasal ulcers and renal congestion was observed. Main histologic lesions were multifocal, accentuated, necrotizing and hemorrhagic abomasitis and omasitis, and tubular necrosis in the kidneys. Mean arsenic concentrations in cows with clinical signs were 1.19±0.40, 10.52±2.16, and 76.06±48.37ppm in blood, milk, and feces, respectively. In the two necropsied cows arsenic concentrations were 25.58 and 23.85ppm in liver, and 28.71 and 35.94ppm in kidney, respectively. In a fetus of a cow that was necropsied, arsenic concentrations were 9.0 and 8.92ppm in liver and kidney, respectively. Arsenic concentration in the grass collected from the paddock sprayed with MSMA was 111.58ppm. In Brazil, the use of MSMA in the composition of herbicides is allowed only for agricultural use, not for livestock. The use of arsenic based products for livestock can lead to high mortality rates in the herd, as well as reduced production and contamination of animal products.",
Arsenic,1250985,"Phosphate-Catalyzed Degradation of d-Glucosone in Aqueous Solution Is Accompanied by C1-C2 Transposition Abstract: Pathways in the degradation of the C(6) 1,2-dicarbonyl sugar (osone) d-glucosone 2 (d-arabino-hexos-2-ulose) in aqueous phosphate buffer at pH 7.5 and 37 °C have been investigated by (13)C and (1)H NMR spectroscopy with the use of singly and doubly (13)C-labeled isotopomers of 2. Unlike its 3-deoxy analogue, 3-deoxy-d-glucosone (3-deoxy-d-erythro-hexos-2-ulose) (1), 2 does not degrade via a 1,2-hydrogen shift mechanism but instead initially undergoes C1-C2 bond cleavage to yield d-ribulose 3 and formate. The latter bond cleavage occurs via a 1,3-dicarbonyl intermediate initially produced by enolization at C3 of 2. However, a careful monitoring of the fates of the sketetal carbons of 2 during its conversion to 3 revealed unexpectedly that C1-C2 bond cleavage is accompanied by C1-C2 transposition in about 1 out of every 10 transformations. Furthermore, the degradation of 2 is catalyzed by inorganic phosphate (P(i)), and by the P(i)-surrogate, arsenate. C1-C2 transposition was also observed during the degradation of the C(5) osone, d-xylosone (d-threo-pentose-2-ulose), showing that this transposition may be a common feature in the breakdown of 1,2-dicarbonyl sugars bearing an hydroxyl group at C3. Mechanisms involving the reversible formation of phosphate adducts to 2 are proposed to explain the mode of P(i) catalysis and the C1-C2 transposition. These findings suggest that the breakdown of 2 in vivo is probably catalyzed by P(i) and likely involves C1-C2 transposition.",
Arsenic,459263,"Impaction collection and slurry sampling for the determination of arsenic, cadmium, and lead in sidestream cigarette smoke by inductively coupled plasma-mass spectrometry Abstract: The slurry sampling technique has been applied for the determination of arsenic, cadmium and lead in sidestream cigarette smoke condensate ( SS CSC) by inductively coupled plasma mass spectrometry ( ICPMS). The smoke collection system consists of a ""fishtail"" chimney in conjunction with an impaction trap and a mixed cellulose ester ( MCE) backup filter for the SS CSC collection. The smoke condensates, collected at three different regions of the system ( i.e. the inner wall of the chimney, the impaction trap and the MCE filter), were individually prepared and analyzed and showed that about 70 and 20% of Cd and Pb, respectively, were trapped by the impaction trap and the MCE filter with less than 5% trapped by the chimney. In contrast, about 60% of As was trapped by the impactor and a relatively high percentage of As, about 30%, was deposited onto the inner wall of the chimney. The uneven distribution of trace metals at each collection stage strongly suggested that the composition of smoke aerosol and the associated physical form of the analytes may be different. The yields of As, Cd and Pb for the sidestream cigarette smoke of the 1R4F reference cigarette were 29.5 +/- 2.4, 421 +/- 6.6 and 46.4 +/- 0.9 ng cigarette(-1) ( n = 3) respectively, when the cigarette was smoked according to the smoking regime: 45 mL puff volume of 2-s puff duration at an interval of 30 s with 50% ventilation holes covered. The analytical results for the slurry sampling technique were also compared with other sample preparation techniques and show good agreement.",
Arsenic,1337586,"Arsenic inhibits the adipogenic differentiation of mesenchymal stem cells by down-regulating peroxisome proliferator-activated receptor gamma and CCAAT enhancer-binding proteins Abstract: Arsenic remains a top environmental concern in the United States as well as worldwide because of its global existence and serious health impacts. Apoptotic effect of arsenic in human mesenchymal stem cells (hMSCs) has been identified in our previous study; the effects of arsenic on hMSCs remain largely unknown. Here, we report that arsenic inhibits the adipogenic differentiation of human mesenchymal stem cells (hMSCs). Arsenic reduced the formation of lipid droplets and the expression of adipogenesis-related proteins, such as CCAAT enhancer binding protein-(C/EBPs), peroxisome proliferator-activated receptor-gamma (PPAR-?), and adipocyte fatty acid-binding protein aP2 (aP2). Arsenic mediates this process by sustaining PPAR-? activity. In addition, inhibition of PPAR-? activity with T0070907 and up-regulation with its agonist troglitazone, showed the direct association of PPAR-? and arsenic-mediated inhibition of differentiating hMSCs. Taken together, these results indicate that arsenic inhibits adipogenic differentiation through PPAR-? pathway and suggest a novel inhibitory effect of arsenic on adipogenic differentiation in hMSCs.",
Arsenic,2149282,"Biosorption of arsenite (As+3) and arsenate (As+5) from aqueous solution by Arthrobacter sp biomass Abstract: In this study we investigated the role of arsenic-resistant bacteria Arthrobacter sp. biomass for removal of arsenite as well as arsenate from aqueous solution. The biomass sorption characteristics were studied as a function of biomass dose, contact time and pH. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm. The Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The biosorption capacity of the biomass for As+3 and As+5 was found to be 74.91mg/g (pH 7.0) and 81.63mg/g (pH 3.0), respectively using 1g/L biomass with a contact time of 30 min at 28 degrees C. The mean sorption energy values calculated from the D-R model indicated that the biosorption of As+3 and As+5 onto Arthrobacter sp. biomass took place by chemical ion-exchange. The thermodynamic parameters showed that the biosorption of As+3 and As+5 ions onto Arthrobacter sp. biomass was feasible, spontaneous and exothermic in nature. Kinetic evaluation of experimental data showed that biosorption of As+3 and As+5 followed pseudo-second-order kinetics. Fourier transform infrared spectroscopy (FT-IR) analysis indicated the involvement of possible functional groups (OH, C\dbond O and NH) in the As+3 and As+5 biosorption process. Bacterial cell biomass can be used as a biosorbent for removal of arsenic from arsenic-contaminated water.",
Arsenic,2347616,"Speciation analysis of inorganic arsenic in river water by Amberlite IRA 910 resin immobilized in a polyacrylamide gel as a selective binding agent for As(v) in diffusive gradient thin film technique Abstract: In this study, a method is proposed for the selective retention of As(v) using diffusive gradient in thin film (DGT) samplers containing a strongly basic anion exchange resin (Amberlite IRA 910) supported on a polyacrylamide gel. In addition, the total arsenic content is determined by ferrihydrite gel discs. Subsequently, the concentration of As(iii) was obtained by determining the difference between the total As and As(v). DGT experiments showed linear accumulation of As(v) (up to 280 ng) until a deployment time of 8 h deployment (R(2) &gt; 0.99). The retention of As(v) was appropriate (97.9-112.3%) between pH 5 and 9. For a solution with an ionic strength ranging from 0.001 to 0.05 mol L(-1), the As(v) uptake ranged from 90-120%. The proposed method was applied for the speciation of arsenic in river water. For the analysis of spiked samples collected at the Furnas stream, the recoveries of total arsenic content ranged between 103.9% and 118.8%. However, the recoveries of As(iii) and As(v) were 43.3-75.2% and 147.3-153.4%, respectively. These differences were probably because of the oxidation of As(iii) to As(v) during deployments. For spiked samples collected at the Ribeirão Claro, the recoveries of dissolved As(iii), As(v) and As(T) were 103.1%, 108.0% and 106.3%, respectively. Thus, the DGT technique with Amberlite IRA 910 resin as the binding phase can be employed for the in situ redox speciation of inorganic arsenic.",
Arsenic,710847,"Arsenic-associated oxidative stress, inflammation, and immune disruption in human placenta and cord blood Abstract: Arsenic (As) exposure during pregnancy induces oxidative stress and increases the risk of fetal loss and low birth weight.<br /><br /> In this study we aimed to elucidate the effects of As exposure on immune markers in the placenta and cord blood, and the involvement of oxidative stress.<br /><br /> Pregnant women were enrolled around gestational week (GW) 8 in our longitudinal, population-based, mother-child cohort in Matlab, an area in rural Bangladesh with large variations in As concentrations in well water. Women (n = 130) delivering at local clinics were included in the present study. We collected maternal urine twice during pregnancy (GW8 and GW30) for measurements of As, and placenta and cord blood at delivery for assessment of immune and inflammatory markers. Placental markers were measured by immunohistochemistry, and cord blood cytokines by multiplex cytokine assay.<br /><br /> In multivariable adjusted models, maternal urinary As (U-As) exposure both at GW8 and at GW30 was significantly positively associated with placental markers of 8-oxoguanine (8-oxoG) and interleukin-1? (IL-1?); U-As at GW8, with tumor necrosis factor-? (TNF?) and interferon-? (IFN?); and U-As at GW30, with leptin; U-As at GW8 was inversely associated with CD3+ T cells in the placenta. Cord blood cytokines (IL-1?, IL-8, IFN?, TNF?) showed a U-shaped association with U-As at GW30. Placental 8-oxoG was significantly positively associated with placental proinflammatory cytokines. Multivariable adjusted analyses suggested that enhanced placental cytokine expression (TNF? and IFN?) was primarily influenced by oxidative stress, whereas leptin expression appeared to be mostly mediated by As, and IL-1? appeared to be influenced by both oxidative stress and As.<br /><br /> As exposure during pregnancy appeared to enhance placental inflammatory responses (in part by increasing oxidative stress), reduce placental T cells, and alter cord blood cytokines. These findings suggest that effects of As on immune function may contribute to impaired fetal and infant health.",
Arsenic,1030133,"The transition from late G1 to early S phase is most vulnerable to the coclastogenic effect of ultraviolet radiation plus arsenite Abstract: It has previously been reported that chromosome aberrations induced by ultraviolet (UV) radiation can be enhanced by treatment with sodium arsenite for 24 h post-irradiation. Using synchronized CHO-K1 cells, it has now been established that cells in the transitional stage from late G1 to early S phase are most vulnerable to the coclastogenic effect of treatment with UV radiation and arsenite. This result cannot be explained by the special vulnerability of cells in the late G1 to early S transition to UV clastogenicity, as the coclastogenic effects of UV and caffeine or UV and arabinofuranosylcytosine were detected when treating the mid-S but not late-G1 or G2 phase cells.",
Arsenic,1936085,"Preconcentration determination of arsenic species by sorption of As(v) on Amberlite IRA-410 coupled with fluorescence quenching of l-cysteine capped CdS nanoparticles Abstract: A simple and accurate method for arsenic speciation analysis in natural and drinking water samples is described in which preconcentration of arsenic as As(v) was coupled with spectrofluorometric determination. The extracted As(v) species with a column containing Amberlite IRA-410 were subjected to l-cysteine capped CdS quantum dots (QDs) and the fluorescence quenching of the QDs due to reduction of As(v) by l-cysteine was considered as a signal relevant to As(v) concentration. The As(iii) species were also determined after oxidation of As(iii) ions to As(v) with H2O2 and measurement of the total arsenic content. In treatment with 400 mL portions of water samples containing 30 ?g L(-1) As(v), the relative standard deviation was 2.8%. The detection limit of arsenic was also found to be 0.75 ?g L(-1) (1 × 10(-8) M). The reliability of proposed method was confirmed using certified reference materials. The trace amounts of arsenic species were then determined in different water samples, satisfactorily.",
Arsenic,2345609,"Role of endometrial concentrations of heavy metals (cadmium, lead, mercury and arsenic) in the aetiology of unexplained infertility Abstract: <strong>OBJECTIVE: </strong>To determine the role of endometrial concentrations of heavy metals (cadmium, lead, mercury and arsenic) in the aetiology of unexplained infertility.<br /><br /><strong>STUDY DESIGN: </strong>Thirty-three women with unexplained infertility and 32 fertile women were recruited. Endometrial biopsies were collected during the putative window of implantation (cycle days 20-24). The concentrations of cadmium, lead, mercury and arsenic were measured in endometrial biopsy specimens using atomic absorption spectrometry.<br /><br /><strong>RESULTS: </strong>Cadmium was detected in 91% (30/33) of women with unexplained infertility, compared with 34% (11/32) of fertile women. The median endometrial cadmium concentration was 19.58 (interquartile range 1.46-30.23)?g/l in women with unexplained infertility, compared with 0.00 (interquartile range 0.00-0.40)?g/l in fertile women. Lead was detected in 15% (5/33) of women with unexplained infertility and 3% (1/32) of fertile women. Mercury and arsenic were not detected in any endometrial samples from either group.<br /><br /><strong>CONCLUSION: </strong>A significant difference in endometrial cadmium concentration was found between women with unexplained infertility and fertile women. This suggests that cadmium may be a contributing factor in the aetiology of unexplained infertility.",
Arsenic,2338271,"Direct removal of aqueous As(III) and As(V) by amorphous titanium dioxide nanotube arrays Abstract: Amorphous titanium dioxide nanotube arrays (TiO2 NTs) were prepared by a simple anodization process without subsequent calcination at high temperature, and the effectiveness of amorphous TiO2 NTs as adsorbents in removing arsenite (As(III)) and arsenate (As(V)) was investigated. The TiO2 NTs were not only effective for arsenic removal without a pre-oxidation of As(III) to As(V) and/or adjusting the pH value of water before the adsorption process, but also can be separated and recovered easily from the solution. The adsorption kinetics and adsorption capacity of the amorphous TiO2 NTs for As(III) and As(V) were studied separately by batch experiments. The apparent values for Langmuir monolayer sorption capacities were 28.9 mg/g for As(III) and 24.7 mg/g for As(V) at pH 7. Kinetics studies indicated that the adsorption process on TiO2 NTs followed a pseudo-second-order kinetics model. Arsenic adsorption of TiO2 NTs remains stable over a broad pH range. Moreover, the TiO2 NTs have excellent stability and regeneration, and they can be used repeatedly at least five times.",
Arsenic,627429,"Effects of arsenite on cell cycle progression in a human bladder cancer cell line Abstract: Bladder cancer is one of the most important diseases associated with arsenic (As) exposure in view of its high prevalence and mortality rate. Experimental studies have shown that As exposure induces cell proliferation in the bladder of sodium arsenite (iAsIII) subchronically treated mice. However, there is little available information on its effects on the cell cycle of bladder cells. Thus, our purpose was to evaluate the effects of iAsIII on cell cycle progression and the response of p53 and p21 on the human-derived epithelial bladder cell line HT1197. iAsIII treatment (1-10 microM) for 24 h induced a dose-dependent increase in the proportion of cells in S-phase, which reached 65% at the highest dose. A progressive reduction in cell proliferation was also observed. BrdU was incorporated to cellular DNA in an interrupted form, suggesting an incomplete DNA synthesis. The time-course of iAsIII effects (10 microM) showed an increase in p53 protein content and a transient increase in p21 protein levels accompanying the changes in S-phase. These effects were correlated with iAs concentrations inside the cells, which were not able to metabolize inorganic arsenic. Our findings suggest that p21 was not able to block CDK2-cyclin E complex activity and was therefore unable to arrest cells in G1 allowing their progression into the S-phase. Further studies are needed to ascertain the mechanisms underlying the effects of iAsIII on the G1 to S phase transition in bladder cells.",
Arsenic,1021767,"Monomethylarsenic diglutathione transport by the human multidrug resistance protein 1 (MRP1/ABCC1) Abstract: The ATP-binding cassette (ABC) transporter protein multidrug resistance protein 1 (MRP1; ABCC1) plays an important role in the cellular efflux of the high-priority environmental carcinogen arsenic as a triglutathione conjugate [As(GS)(3)]. Most mammalian cells can methylate arsenic to monomethylarsonous acid (MMA(III)), monomethylarsonic acid (MMA(V)), dimethylarsinous acid (DMA(III)), and dimethylarsinic acid (DMA(V)). The trivalent forms MMA(III) and DMA(III) are more reactive and toxic than their inorganic precursors, arsenite (As(III)) and arsenate (As(V)). The ability of MRP1 to transport methylated arsenicals is unknown and was the focus of the current study. HeLa cells expressing MRP1 (HeLa-MRP1) were found to confer a 2.6-fold higher level of resistance to MMA(III) than empty vector control (HeLa-vector) cells, and this resistance was dependent on GSH. In contrast, MRP1 did not confer resistance to DMA(III), MMA(V), or DMA(V). HeLa-MRP1 cells accumulated 4.5-fold less MMA(III) than HeLa-vector cells. Experiments using MRP1-enriched membrane vesicles showed that transport of MMA(III) was GSH-dependent but not supported by the nonreducing GSH analog, ophthalmic acid, suggesting that MMA(III)(GS)(2) was the transported form. MMA(III)(GS)(2) was a high-affinity, high-capacity substrate for MRP1 with apparent K(m) and V(max) values of 11 ?M and 11 nmol mg(-1)min(-1), respectively. MMA(III)(GS)(2) transport was osmotically sensitive and inhibited by several MRP1 substrates, including 17?-estradiol 17-(?-D-glucuronide) (E(2)17?G). MMA(III)(GS)(2) competitively inhibited the transport of E(2)17?G with a K(i) value of 16 ?M, indicating that these two substrates have overlapping binding sites. These results suggest that MRP1 is an important cellular protective pathway for the highly toxic MMA(III) and have implications for environmental and clinical exposure to arsenic.",
Arsenic,1337371,"Distribution and relationships of As, Cd, Pb and Hg in freshwater fish from five French fishing areas Abstract: The concentrations of arsenic, cadmium, mercury and lead in 149 muscle samples of eight freshwater fish species (European eel, bream, common carp, European catfish, roach, perch, pike and pikeperch) from five different French fishing areas from contaminated and control sites were measured by inductively coupled plasma mass spectrometry after microwave digestion under pressure. No significant correlation was found between the condition factor (CF), based on the length-mass relationship, and As, Cd and Pb levels in all the samples analysed, but a positive correlation was detected between CF and Hg levels (P&lt;0.0001, R=0.49). Positive correlations with body length were only found for Hg in roach (P&lt;0.05, R=0.32) and Pb in bream (P&lt;0.05, R=0.48) and correlations with both body weight and length were also found for Hg in pike (P&lt;0.05, R=0.90 and 0.86) and Cd in European eel (P&lt;0.01, R=-0.35 and -0.37). The average content and the standard deviation in fish muscle samples was 0.007±0.012, 0.102±0.077, 0.142±0.097 and 0.035±0.053mgkg(-1) of wet mass for Cd, As, Hg and Pb, respectively. Significant differences were established between groups of predatory fish and non-predatory fish for Hg and Pb, and between control and contaminated sites in the whole selection and also within feeding guilds, i.e. the values of Hg in the benthophagic fish were significantly different between these sites. Finally, these results were also compared for each species with previous French and European studies.",
Arsenic,1029045,"XAS study of arsenic coordination in Euglena gracilis exposed to arsenite Abstract: Among the few eukaryotes adapted to the extreme conditions prevailing in acid mine drainage, Euglenae are ubiquitous in these metal(loid)-impacted environments, where they can be exposed to As(III) concentrations up to a few hundreds of mg x L(-1). In order to evaluate their resistance to this toxic metalloid and to identify associated detoxification mechanisms, we investigated arsenic coordination in the model photosynthetic protozoan, Euglena gracilis, cultured at pH 3.2 and exposed to As(III) at concentrations ranging from 10 to 500 mg x L(-1). E. gracilis is shown to tolerate As(III) concentrations up to 200 mg * L(-1), without accumulating this metalloid. X-ray absorption spectroscopy at the As K-edge shows that, in the cells, arsenic mainly binds to sulfur ligands, likely in the form of arsenic-trisglutathione (As-(GS)3) or arsenic-phytochelatin (As-PC) complexes, and to a much lesser extent to carbon ligands, presumably in the form of methylated As(III)-compounds. The key role of the glutathione pathway in As(III) detoxification is confirmed by the lower growth rate of E. gracilis cultures exposed to arsenic, in the presence of buthionine sulfoximine, an inhibitor of glutathione synthesis. This study provides the first investigation at the molecular scale of intracellular arsenic speciation in E. gracilis and thus contributes to the understanding of arsenic detoxification mechanisms in a eukaryotic microorganism under extreme acid mine drainage conditions.",
Arsenic,2088474,"Modulatory of effect of fresh Amaranthus caudatus and Amaranthus hybridus aqueous leaf extracts on detoxify enzymes and micronuclei formation after exposure to sodium arsenite Abstract: Vegetables are the cheapest and most available sources of important proteins, minerals, vitamins, and essential amino protein. These vegetables are commonly used in Africa for the treatment of illness. This study evaluated the protective effects of Amaranthus caudatus and A. hybridus against sodium arsenite-induced toxicity in rats. The effects of sodium arsenite and/or the plant extracts were assessed using bone marrow micronucleus assay and by measuring the activities of tumour maker enzymes such as gamma glutamyl transferase (GGT) and alkaline phosphatase (ALP) in white albino Wister rats. The study showed that sodium arsenite significantly (P &lt; 0.05) induced the formation of micronucleated polychromatic erythrocytes and the activities of ALP and GGT when compared with control. The levels of white blood cell, hemoglobin, and lymphocyte count were altered in sodium arsenite fed rats and were reverted back to near normal levels in rats pretreated with the plant extracts. A. caudatus and A. hybridus showed significant role in protecting the detoxifying enzymes; also, A. caudatus has a more protective effect on reducing the micronuclei formation when compared with A. hybridus. This study suggests that A. caudatus and A. hybridus possess anticarcinogenic effect.",
Arsenic,1337827,"Arsenic and selenium interactive effect on alga Desmodesmus quadricauda Abstract: Substances known to be toxic in one-component solutions often exhibit unexpected effects when present in mixtures. Only a few efforts have been made to assess the effect of As-Se mixture in algae or plants in general. Due to the lack of information on this topic, the aim of this study was to examine the As-Se interactive effect in the alga species Desmodesmus quadricauda. The initial density of algal cells was 1.9×10(4), cultures were permanently illuminated (70?Em(-2)s(-1)) and As and Se adverse effect was expressed as EC (effective concentration) value. For all experiments three EC (EC(10), EC(20), EC(50)) values for both metalloids were used: for As 26.20, 29.05, 35.38mgL(-1) and for Se 1.93, 3.65, 12.24mgL(-1), respectively. During this study algal biomass growth, lipid peroxidation and protein-bound thiol content parameters were used to assess the As-Se interactions. The reciprocal effect of the elements on their uptake by the alga was also determined. The As-treated algae supplemented with Se exhibited impaired growth indicating a synergistic interaction between the two elements. In samples treated with As-Se mixture, the total algal As content showed marked increase depending on the Se concentration in the mixture. Se uptake was also positively affected by rising As concentrations in the mixture. Consequently, the As-Se-treated algae experienced greater damage to membranes, evidenced by marked elevation of the TBARS (thiobarbituric acid reactive substances) content. The TBARS content increased to a maximum level by 29.05mgL(-1) of As and 3.65mgL(-1) of Se, which was around 70 percent higher than that of the control. The thiol content was very close to that of the control treatment over the entire concentration range and for all As and Se combinations tested. Possible explanation for the synergism observed in D. quadricauda, is that the elevated uptake of As and Se upon their interaction and impaired antioxidant system, has added to the toxicity of the elements.",
Arsenic,1020551,"Distinct roles of c-Abl and Atm in oxidative stress response are mediated by protein kinase C delta Abstract: c-Abl and Atm have been implicated in cell responses to DNA damage and oxidative stress. However, the molecular mechanisms by which they regulate oxidative stress response remain unclear. In this report, we show that deficiency of c-Abl and deficiency of ATM differentially altered cell responses to oxidative stress by induction of antioxidant protein peroxiredoxin I (Prx I) via Nrf2 and cell death, both of which required protein kinase C (PKC) delta activation and were mediated by reactive oxygen species. c-abl-/- osteoblasts displayed enhanced Prx I induction, elevated Nrf2 levels, and hypersusceptibility to arsenate, which were reinstated by reconstitution of c-Abl; Atm-/- osteoblasts showed the opposite. These phenotypes correlated with increased PKC delta expression in c-abl-/- osteoblasts and decreased PKC delta expression in Atm-/- cells, respectively. The enhanced responses of c-abl-/- osteoblasts could be mimicked by overexpression of PKC delta in normal cells and impeded by inhibition of PKC delta, and diminished responses of Atm-/- cells could be rescued by PKC delta overexpression, indicating that PKC delta mediated the effects of c-Abl and ATM in oxidative stress response. Hence, our results unveiled a previously unrecognized mechanism by which c-Abl and Atm participate in oxidative stress response.",
Arsenic,759884,"Arsenic induces DNA damage in environmentally exposed Mexican children and adults. Influence of GSTO1 and AS3MT polymorphisms Abstract: Inorganic arsenic (i-As) is an environmental carcinogen to which millions of people are chronically exposed mainly via drinking water. In this study, we used the comet assay to evaluate DNA damage in i-As-exposed inhabitants of the north of Mexico. The environmental monitoring and the exposure assessment were done by measuring both drinking water arsenic (As) content and total urinary As. In addition, the studied population was genetically characterized for four different glutathione S-transferase omega1 (GSTO1) polymorphisms (Ala140Asp, Glu155del, Glu208Lys, and Ala236Val) and the As (+3 oxidation state) methyltransferase (AS3MT) Met287Thr polymorphism to determine whether such variants influence As-related genotoxicity. As content in the drinking water of the population was found to range between 1 and 187 microg/l, with a mean concentration value of 16 microg/l. The total urinary As content of the exposed individuals was found to be correlated with the As content in drinking water, and subjects were classified as low (&lt; 30 microg As/g creatinine), medium (31-60 microg As/g creatinine), and highly exposed (&gt; 61 microg As/g creatinine). A positive association was found between the level of exposure and the genetic damage measured as percentage of DNA in tail (p &lt; 0.001), and AS3MT Met287Thr was found to significantly influence the effect (p &lt; 0.034) among children carrying the 287Thr variant allele. Altogether, our results evidenced that people living in As-contaminated areas are at risk and that AS3MT genetic variation may play an important role modulating such risk in northern Mexico, especially among children.",
Arsenic,1021976,"Concentrations of arsenic, chromium, and nickel in toenail samples from Appalachian Kentucky residents Abstract: Lung cancer rates in Appalachian Kentucky are almost twice national rates; colorectal cancer rates are also elevated. Although smoking prevalence is high, it does not explain all excess risk. The area is characterized by poverty, low educational attainment, and unemployment. Coal production is a major industry. Pyrite contaminants of coal contain established human carcinogens, arsenic (As), chromium (Cr), and nickel (Ni). We compared biological exposure to As, Cr, and Ni for adults living in Appalachian Kentucky with residents of Jefferson, a non-Appalachian, urban county. We further compared lung and colon cancer rates, demographics, and smoking prevalence across the study areas. Toenail clipping analysis measured As, Cr, and Ni for residents of 23 rural Appalachian Kentucky counties and for Jefferson County. Reverse Kaplan-Meier statistical methodology addressed left-censored data. Appalachian residents were exposed to higher concentrations of As, Cr, and Ni than Jefferson County residents. Lung cancer incidence and mortality rates in Appalachia are higher than Jefferson County and elsewhere in the state, as are colorectal mortality rates. Environmental factors may contribute to the increased concentration of trace elements measured in residents of the Appalachian region. Routes of human exposure need to be determined.",
Arsenic,628135,"Prevalence of skin lesions and exposure to arsenic in drinking water in Iran Abstract: Prevalence of skin lesions was investigated among 752 participants in eight villages in Kurdistan province in Iran with emphasis on total lifetime intake of arsenic from drinking water (TLIA). The participants were selected from eight villages with different exposure levels using a cluster-sampling technique. TLIA was calculated for each individual taking into account the type of water supply and their mean annual arsenic concentration. The study showed that 49 persons (6.5%) were suffering from hyperkeratosis and 20 persons (2.7%) from hyperpigmentation. The correlation between hyperkeratosis and hyperpigmentation was significant (R=0.325, p<0.01). Using the logistic regression model it was found that the relationship between TLIA and hyperkeratosis (OR=1.14, 95% CI=1.039-1.249), and hyperpigmentation (OR=1.254, 95% CI=1.112-1.416) was also significant. In conclusion, TLIA can be applied as a reliable indicator for the assessment of exposure.",
Arsenic,2278639,"Metal and metalloid leaching from tailings into streamwater and sediments in the old Ag-Pb-Zn Terramonte mine, northern Portugal Abstract: Tailings deposited over the Castanheira, a stream which flows through the old Ag-Pb-Zn Terramonte mine area, showed a great potential environmental risk due to sulphide weathering, facilitated by the tailings-water interaction. The high concentrations of Al, Fe, Pb and Zn in the tailings are associated with the exchangeable, reducible and sulphide fractions and suggest sphalerite and pyrite occurrences. Oxidation of pyrite is responsible for the low pH values (3.38-4.89) of the tailings. The water from the Castanheira stream is not suitable for human consumption due to high concentrations of SO4 (2-), Mn, Al, Cd, Ni, and Pb. The lowest concentrations of metals and metalloids were detected in downstream stretches of the Castanheira. However, As, Fe and Zn in deeper sediments tend to increase downstream. Significant concentrations of trivalent forms of arsenic were detected in water samples. In downstream stretches of the Castanheira, some free ions (Fe2+, Mn2+ and Zn2+) also predominate and the water is saturated with ferrihydrite, goethite, hematite, lepidocrosite and magnetite.",
Arsenic,1936071,The WKRY6 Transcription Factor Is a Key Player in a Multifaceted Defense against Arsenate Abstract: ,
Arsenic,1172923,"Measurement Of Multiple Inorganic Arsenic Species Abstract: A technique was developed to separate mixtures of particulate inorganic arsenic compounds and arsine (7784421), and to detect arsenic-trioxide (1327533) vapor. A 13 millimeter (mm) filter/charcoal tube system, a 37mm filter, and a 37mm carbon treated filter were compared for particulate and arsine collection characteristics. Experiments were conducted in exposure chambers and at a battery manufacturing facility, and arsenic was measured with atomic absorption spectrometry. Algorithms were used to resolve the arsenic species. The experimental technique consisted of a sampling train with a 1.2mm inlet orifice, a 13mm cellulose ester filter without back up pad, and a standard 150 milligram charcoal tube. Air was drawn through the inlet, filter, and tube at 0.2 liters per minute. In the laboratory experiment, there was no significant difference between the collection characteristics of the 13mm filter/charcoal tube system and the 37mm filter; collection efficiency was 1.0. No measurable arsine was collected on any of the filters. In the field study, the particulate collection efficiencies of the three filters were identical; however, the 13mm filter collected less total arsenic than the 37mm filter, which in turn collected less than the carbon treated filter. The carbon treated filter had the highest arsenic-trioxide vapor efficiency at 98 percent, followed by the 37mm filter/back up pad combination at 81 percent. Collection efficiency of the 13mm filter was 35 percent; however, the arsenic-trioxide vapor which penetrated the 13mm filter was collected with 96 percent efficiency by the charcoal tube. The carbon treated filter was unable to detect arsine. Both the 13mm and 37mm filters, when used with the charcoal tube, were able to detect arsine with 100 percent efficiency. The authors conclude that the 13mm filter/charcoal tube sampling train effectively separates particulate arsenic from arsine and can be used to collect personal exposure data. Used by itself, the carbon treated filter is a more efficient collector of arsenic-trioxide vapor than the classical filter method, and is an equivalent collector of particulate arsenic.",
Arsenic,1597414,"Evaluation of natural phytoremediation process occurring at ex-tin mining catchment Abstract: Removal of heavy metals from soil and water by plants (Phytoremediation) has appeared as a promising cost-effective technology. Nine plant species such as Cyperus rotundus L., Imperata cylindrica, Lycopodium cernuum, Melastoma malabathricum, Mimosa pudica Linn, Nelumbo nucifera, Phragmites australis L., Pteris vittata L. and Salvinia molesta, were selected according to previous studies on these plant species conducted by author. These plant species analysed to assess the phytoextraxtion potential for remediation of lead (Pb), copper (Cu), zinc (Zn), arsenic (As) and tin (Sn) from contaminated tin tailings. Results showed that Cyperus rotundus L., accumulated 658 mg kg-1, Imperata cylindrica accumulated 245 mg kg-1, Nelumbo nucifera accumulated 288 mg kg-1, Phragmites australis L., accumulated 345 mg kg-1 and Pteris vittata L. accumulated 278 mg kg-1 (dry weight) with bioconcentration factors up to 0.40, 0.32, 0.57, 0.71 and .65, respectively. The phytoextraction rates of Cyperus rotundus L. (86%) for Sn, Imperata cylindrica (42%) for Zn, Nelumbo nucifera (56%) for As, Phragmites australis L.(49%) for Cu and Pteris vittata L. (31%) for Pb, were recorded. It can be concluded that candidate plant species could successfully be used for phytoremediation of mining tin tailings in Peninsular Malaysia.",
Arsenic,2064286,"Removal of arsenic from groundwater by using a native isolated arsenite-oxidizing bacterium Abstract: Arsenic (As) contamination of groundwater is a significant public health concern. In this study, the removal of arsenic from groundwater using biological processes was investigated. The efficiency of arsenite (As(III)) bacterial oxidation and subsequent arsenate (As(V)) removal from contaminated groundwater using bacterial biomass was examined. A novel As(III)-oxidizing bacterium (As7325) was isolated from the aquifer in the blackfoot disease (BFD) endemic area in Taiwan. As7325 oxidized 2300?g/l As(III) using in situ As(III)-contaminated groundwater under aerobic conditions within 1d. After the oxidation of As(III) to As(V), As(V) removal was further examined using As7325 cell pellets. The results showed that As(V) could be adsorbed efficiently by lyophilized As7325 cell pellets, the efficiency of which was related to lyophilized cell pellet concentration. Our study conducted the examination of an alternative technology for the removal of As(III) and As(V) from groundwater, indicating that the oxidation of As(III)-contaminated groundwater by native isolated bacterium, followed by As(V) removal using bacterial biomass is a potentially effective technology for the treatment of As(III)-contaminated groundwater.",
Arsenic,1508687,"Characterization of arsenic induced cytotoxicity in liver with stress in erythrocytes and its reversibility with Pleurotus florida lectin Abstract: Arsenic is one of the most hazardous substances in the environment known to cause toxicity in multiple organs. Cell adhesion, morphological alterations, cell proliferation, terminal deoxyuridine triphosphate nick-end labeling (TUNEL) and caspase-3/CPP32 fluorometric protease assay were important biomarkers to assess apoptosis in cells. This study aimed to evaluate arsenic-induced apoptosis in the hepatocytes of rat and its protective efficacy with coadministration of ascorbic acid (AA) and Pleurotus florida lectin (PFL) individually. Results of the present study also showed that arsenic caused cytotoxicity by elevating morphological alterations, TUNEL-positive nuclei, caspase-3 activity and DNA damage and reducing cell adhesion and cell proliferation in a time-dependent manner. The apoptosis in hepatocytes was reverted to normal value after coadministration of mushroom lectin in arsenic-exposed rat. The study provided significant evidence that PFL has antiapoptotic property against arsenic-induced toxicity. The beneficial effect of PFL was proportional to its duration of exposure. Retard activities of superoxide dismutase and catalase, enhanced lipid peroxidation as well as protein carbonyl in erythrocytes caused by arsenic could also be maintained toward normalcy by supplementation of AA and PFL. These antioxidative effects were exhibited in a time-dependant manner. In rat, treatment with AA and PFL prevented alteration of plasma enzyme activities caused by arsenic. The results concluded that treatment with PFL has significant role in protecting animals from arsenic-induced erythrocytic damage. This finding might be of therapeutic benefit in people suffering from chronic exposure to arsenic from natural sources, a global problem especially relevant to millions of people on the Indian subcontinent.",
Arsenic,627938,"Early induction of genetic instability and apoptosis by arsenic in cultured Chinese hamster cells Abstract: In order to assess at what time from the beginning of exposure inorganic arsenic can give rise to genetic instability and trigger apoptosis, V79-C13 Chinese hamster cells were treated with 10 microM sodium arsenite for 24 h. Under these conditions, cell survival was >70% and cells showed neither an increase in chromosome aberration frequency nor a delay in cell cycle progression. Investigations, which were carried out every 6 h during the treatment, revealed an early appearance of genetically unstable cells, namely micronucleated, multinucleated and mononucleated 'giant' cells, as well as apoptotic cells. Indirect immunostaining using anti-beta-tubulin antibody showed severe alterations in spindle morphology after only 6 h treatment, when cells with small spindles whose poles were inside the metaphase plate appeared, and after 12 h treatment, when cells in which spindle assembly had completely failed were observed. These cells, unable to complete mitosis, underwent apoptosis. In fact, cells which turned out to be positive in the TdT-FragEL test had condensed chromatin arranged in metaphase-like plates; their maximum frequency was reached after 24 h treatment. A cytogenetic study was conducted at the end of the period of exposure to arsenic and after post-treatment incubation in fresh medium for up to 5 days. It showed that the percentage of cells with 21 chromosomes (modal number of the cell line) decreased, making way for aneuploid cells. Arsenic, therefore, induced early genetic instability or apoptosis in dividing cells. However, while apoptosis tended to cease when arsenic was removed from the culture medium, the acquired instability remained and propagated within the cell population.",
Arsenic,2337114,"Effects on the mobility of metals from acidification caused by possible CO2 leakage from sub-seabed geological formations Abstract: Carbon dioxide capture and storage (CCS) in submarine geological formations has been proposed as a mitigation measure for the prevention of global warming. However, leakage of CO2 to overlying sediments may occur over time, leading to various effects on ecosystems. Laboratory-scale experiments were performed, involving direct release of carbon dioxide into sediment, inside non-pressurized chambers, in order to provide data on the possible effects of CO2 leakage from geological storage sites on the fate of several metals. Marine sediments from three sites with different levels of contamination were sampled and submitted to acidification by means of CO2 injection. The experiment lasted 10 days and sediment samples were collected at the beginning and end of the experiment and pore water was extracted for metal analysis. The results revealed that mobility of metals from sediment to pore water depends on the site, metal and length of time exposed. Mobilization of the metals Al, Fe, Zn, Co, Pb and Cu increases with acidification, and this response generally increases with time of exposure to CO2 injection. The geochemical model applied suggests that acidification also influences the speciation of metals, transforming metals and metalloids, like As, into species much more toxic to biota. The data obtained from this study will be useful for calculating the potential risk of CCS activities to the marine environment. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,1018055,"Pesticide use and cutaneous melanoma in pesticide applicators in the Agricultural Heath Study Abstract: <strong>BACKGROUND: </strong>Melanoma rates continue to increase; however, few risk factors other than sun sensitivity and ultraviolet radiation (including sun exposure) have been identified. Although studies of farmers have shown an excess risk of melanoma and other skin cancers, it is unclear how much of this is related to sun exposure compared with other agricultural exposures.<br /><br /><strong>METHODS: </strong>We examined dose-response relationships for 50 agricultural pesticides and cutaneous melanoma incidence in the Agricultural Health Study cohort of licensed pesticide applicators, along with ever use of older pesticides that contain arsenic. Logistic regression was used to examine odds ratios (ORs) and 95% confidence intervals (CIs) associated with pesticide exposure adjusted for age, sex, and other potential confounders.<br /><br /><strong>RESULTS: </strong>We found significant associations between cutaneous melanoma and maneb/mancozeb (&gt;or= 63 exposure days: OR = 2.4; 95% CI, 1.2-4.9; trend p = 0.006), parathion (&gt;or= 56 exposure days: OR = 2.4; 95% CI, 1.3-4.4; trend p = 0.003), and carbaryl (&gt;or= 56 exposure days: OR = 1.7; 95% CI, 1.1-2.5; trend p = 0.013). Other associations with benomyl and ever use of arsenical pesticides were also suggested.<br /><br /><strong>CONCLUSIONS: </strong>Most previous melanoma literature has focused on host factors and sun exposure. Our research shows an association between several pesticides and melanoma, providing support for the hypotheses that agricultural chemicals may be another important source of melanoma risk.",
Arsenic,627078,"Mitogenic signal transduction caused by monomethylarsonous acid in human bladder cells: Role in arsenic-induced carcinogenesis Abstract: Previous studies have shown that human bladder cells (UROtsa), a target of arsenic-induced cancer, can biotransform arsenite to monomethylarsonous acid (MMA(III)), which is more cytotoxic and capable of transforming the UROtsa cells following long-term, low-level exposure. Cyclooxygenase-2 (COX-2) causes hyperplasia in bladder cells and is considered a key biomarker in bladder cancer. To investigate the role of mitogenic pathway stimulation in MMA(III)-induced transformation, UROtsa cells were treated with 50nM MMA(III) for 12, 24, or 52 weeks and analyzed by Western blot for COX-2 expression. Elevations in COX-2 expression were noted following chronic MMA(III) exposure, and this induction increased with duration of exposure, suggesting that COX-2 or the signal transduction pathways responsible for COX-2 protein expression may play a role in MMA(III)-induced transformation. Acute exposure studies found MMA(III) treatment (10, 50, and 100nM, 4 h) induced COX-2 in UROtsa cells with the lowest doses (10 and 50nM) causing the strongest induction. Using pharmacological inhibitors of various pathways, it was shown that epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK-1/-2), phosphoinositide 3-kinase (PI3K), and src were important in the induction of COX-2 by MMA(III). ERK-2 phosphorylation was verified by Western blot analysis with a peak at 15 min, and c-jun was translocated to the nucleus following 50nM MMA(III) treatment. To determine MMA(III) targets, receptors of the erythroblastosis oncogene family (ErbB) family were further investigated. Chronic MMA(III) exposure led to upregulation of the EGFR or ErbB1. Short-term MMA(III) treatment caused the phosphorylation of ErbB2 in its autophosphorylation site. To verify the importance of these signaling pathways to the growth of the MMA(III)-transformed UROtsa cells in soft agar, various inhibitors were used to block pathways and monitor cells growth. Pathways of importance in anchorage-independent growth of UROtsa cells chronically exposed to MMA(III) are src, PI3K, and COX-1 and -2. As COX-2 is an important mediator that contributes to carcinogenesis via promotion of cell proliferation, inhibition of cell death, induction of angiogenesis, and facilitation of invasion, and it is highly upregulated both acutely and chronically in the MMA(III)-transformed cells, it is likely that activation of the mitogen-activated protein kinase pathway and increased COX-2 expression is a plausible mechanism for MMA(III) bladder carcinogenesis.",
Arsenic,1020295,"Predictive value of human biomonitoring in environmental medicine: experiences at the outpatient unit of environmental medicine (UEM) of the University Hospital Aachen, Germany Abstract: There is little data on the distribution of biomonitoring parameters in patients at outpatient Units of Environmental Medicine (UEM). We evaluated the biomonitoring parameters of 646 UEM outpatients from our University Hospital 1988-1998. Few patients were exposed to specific substances. Data of patients who were not obviously exposed was analysed statistically (geometric mean, standard deviation, median, 95th percentile). Results were compared with reference values in literature. Normal distribution of biomonitoring parameters was rare. 95th percentiles for arsenic, chromium, selenium, zinc, phenol and toluene were below standard, 95th percentiles for copper and mercury above, and 95th percentiles for lead, cadmium, pentachlorophenol, lindane, and beta-hexachlorocyclohexane were within the published range of reference values. Thallium as well as most volatile organic compounds analyzed were below detection levels. Aluminum and fluorine exposure was rarely analysed. In view of these results, it is concluded that the indication for biomonitoring needs to be stringent as levels of biomonitoring parameters are generally not risen in patients of the UEM.",
Arsenic,661305,"Soft tissue sarcoma and non-Hodgkin's lymphoma in relation to phenoxyherbicide and chlorinated phenol exposure in western Washington Abstract: A population-based case-control study was conducted in western Washington State to evaluate the relationship between occupational exposure of men aged 20-79 to phenoxyacetic acid herbicides and chlorinated phenols and the risks of developing soft tissue sarcoma (STS) and non-Hodgkin's lymphoma (NHL). Occupational histories and other data were obtained by personal interviews for 128 STS cases and 576 NHL cases, diagnosed between 1981 and 1984, and for 694 randomly selected controls without cancer. Among the study subjects with any past occupational exposure to phenoxyherbicides, the estimated relative risk and 95% confidence interval of developing STS was 0.80 (0.5-1.2), and of developing NHL, 1.07 (0.8-1.4). Risk estimates of developing STS and NHL associated with past chlorophenol exposure were 0.99 (0.7-1.5) and 0.99 (0.8-1.2), respectively. No increasing risk of either cancer was associated with overall duration or intensity of chemical exposure or with exposure to any specific phenoxyherbicide per se. However, estimated risks of NHL were elevated among men who had been farmers, 1.33 (1.03-1.7), forestry herbicide applicators, 4.80 (1.2-19.4), and for those potentially exposed to phenoxyherbicides in any occupation for 15 years or more during the period prior to 15 years before cancer diagnosis, 1.71 (1.04-2.8). Increased risks of NHL were also observed among those with occupational exposure to organochlorine insecticides, such as DDT [1.82 (1.04-3.2)] and organic solvents [1.35 (1.06-1.7)], and to other chemicals typically encountered in the agricultural, forestry, or wood products industries. These results demonstrate small but significantly increased risks of developing NHL in association with some occupational activities where phenoxyherbicides have been used in combination with other types of chemicals, particularly for prolonged periods. They do not demonstrate a positive association between increased cancer risks and exposure to any specific phenoxyherbicide product alone. Moreover, these findings provide no evidence of increased risks of developing NHL associated with chlorinated phenol exposure or of developing STS associated with exposure to either class of chemical.",
Arsenic,1579326,"Results From a Single-Blinded Randomized Study (APPROVAL) Comparing The Impact of Different Ablation Strategies on Long Term Procedure Outcome in Coexistent Atrial Fibrillation and Flutter Abstract: BACKGROUND: This study examined the impact of different ablation strategies on AF recurrence and quality of life (QoL) in coexistent atrial fibrillation (AF) and flutter (AFL). METHODS AND RESULTS: Three-hundred sixty enrolled patients with documented AF and AFL were blinded and randomized to group 1: AF±AFL ablation (n=182) or Group 2: AFL ablation only (n=178). AF-recurrence was evaluated with event-recording and 7-day Holter at 3, 6, 9 and 12 months follow-up. QoL was assessed at baseline and 12-month follow-up using 4 questionnaires; Medical Outcome Study Short Form, Hospital Anxiety and Depression Score, Beck Depression Inventory and State-Trait Anxiety Inventory. Of the 182 patients in group 1, 58 (63±8 years, 78% male, 59±8% LVEF) had AF+AFL ablation and 124 (61±11 years, 72% male, 59±7% LVEF) had AF ablation only. In group 2 (62±9 years, 76% male, 58±10% LVEF) only flutter was ablated by achieving bidirectional isthmus conduction block. Baseline characteristics were not different across groups. At 21±9 months follow-up, 125 (69%) in group 1 and 34 (19%) in group 2 were arrhythmia-free (p &lt;0.001). In group 1, scores on most QoL subscales showed significant improvement at follow-up, whereas group 2 patients derived relatively minor benefit. CONCLUSIONS: In coexistent AF and AFL, lower recurrence rate and better QoL is associated with AF ablation only or AF +AFL ablation, than with lone AFL ablation. Furthermore, QoL directly correlates with freedom from arrhythmia as shown in this study for the first time, in patients blinded to the procedure. CLINICAL TRIAL REGISTRATION INFORMATION: http://clinicaltrial.gov/. Unique Identifier: NCT01439386.",
Arsenic,198495,"Arsenite-Induced Thymus Atrophy is Mediated by Cell Cycle Arrest: A Characteristic Downregulation of E2F-Related Genes Revealed by a Microarray Approach Abstract: Thymus atrophy is induced by a variety of chemicals, including environmental contaminants and is used as a sensitive index to detect their adverse effects on lymphocytes. In the present study we adopted a toxicogenomics approach to identify the pathways that mediate the atrophy induced by arsenite. We also analyzed gene expression changes observed in the course of thymus atrophy by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dexamethasone (DEX), and estradiol (E2), to determine whether arsenite induces atrophy by activating an arsenite-specific pathway or the same pathways as other chemicals. These compounds were intraperitoneally administered to C57BL/6 mice at doses that reduce thymus weight by approximately 30% within 3 days, and gene expression changes in the thymus 24 h after the administration were analyzed by using microarrays and real-time PCR. The microarray analysis showed that arsenite specifically downregulates a variety of E2F target genes that are involved in cell cycle progression. The same genes were also downregulated when mouse B-cell lymphoma A20 cells were exposed to arsenite. Arsenite exposure of the A20 cells was confirmed to induce cell cycle arrest, mainly in the G1 phase, and reduce cell number. Cell cycle arrest in the G1 phase was also confirmed to occur in the thymocytes of the arsenite-exposed mice. These results indicate that arsenite induces thymus atrophy through E2F-dependent cell cycle arrest. The results of this study also show that analysis of gene expression in thymuses is a useful method of obtaining clues to the pathways that mediate the effects of atrophy-inducing chemicals.",
Arsenic,1579306,"Oxidative stress and MAPK involved into ATF2 expression in immortalized human urothelial cells treated by arsenic Abstract: ATF2 is a subfamily member of AP-1 and has an important role in cellular stress responses. ATF2 has been implicated in a transcriptional response leading to cell migration and malignant tumor progression. However, little is known about the effect of arsenic on expression of ATF2 and regulatory pathways in human urothelial cells. In this study, ATF2 expression was measured in NaAsO2-treated human uroepithelial cell line (SV-HUC-1) with 1, 2, 4, 8 and 10 ?M concentrations in order to provide some basis data for the study on mechanism of bladder cancer induced by arsenic. We found that ATF2 expression levels at 2, 4, 8 and 10 ?M arsenic-treated cells were significantly higher than those of control cells, and the strongest expression occurred in 4 ?M NaAsO2-treated cells. Antioxidants (melatonin) and JNK or p38 inhibitors decreased significantly arsenic-induced ATF2 expression. Taken together, these data indicated that the increasing of ATF2 expression is mediated via oxidative stress induced by arsenic in SV-HUC-1 cells, and JNK or p38 rather than ERK is responsible for arsenic-induced ATF2 expression. ROS were also involved in arsenic induced the activation of JNK and p38 MAPK signaling pathway.",
Arsenic,657866,"Cytotoxic effect of As(III) in Caco-2 cells and evaluation of its human intestinal permeability Abstract: Inorganic arsenic has been classified as a carcinogen for humans (Group I). However, its transit across the human intestinal epithelium has not been characterized. Using Caco-2 cells, the thiol-redox balance and apparent permeability coefficients (P(app)) for As(III) in the apical to basolateral (AP-BL) and basolateral to apical (BL-AP) direction were evaluated. After As(III) exposure, GSH-induced synthesis was observed, increasing the GSH/GSSG ratio by elevating the As(III) concentration. The AP-BL permeabilities decreased as the As(III) concentrations increased, indicating the existence of a mediated transport mechanism. The (BL-AP)/(AP-BL) permeability ratios were higher than unity, suggesting the existence of a secretion process.",
Arsenic,2278980,"Predicting arsenic concentrations in groundwater of San Luis Valley, Colorado: Implications for individual-level lifetime exposure assessment Abstract: Consumption of inorganic arsenic in drinking water at high levels has been associated with chronic diseases. Risk is less clear at lower levels of arsenic, in part due to difficulties in estimating exposure. Herein we characterize spatial and temporal variability of arsenic concentrations and develop models for predicting aquifer arsenic concentrations in the San Luis Valley, Colorado, an area of moderately elevated arsenic in groundwater. This study included historical water samples with total arsenic concentrations from 595 unique well locations. A longitudinal analysis established temporal stability in arsenic levels in individual wells. The mean arsenic levels for a random sample of 535 wells were incorporated into five kriging models to predict groundwater arsenic concentrations at any point in time. A separate validation dataset (n = 60 wells) was used to identify the model with strongest predictability. Findings indicate that arsenic concentrations are temporally stable (r = 0.88; 95 % CI 0.83-0.92 for samples collected from the same well 15-25 years apart) and the spatial model created using ordinary kriging best predicted arsenic concentrations (? = 0.72 between predicted and observed validation data). These findings illustrate the value of geostatistical modeling of arsenic and suggest the San Luis Valley is a good region for conducting epidemiologic studies of groundwater metals because of the ability to accurately predict variation in groundwater arsenic concentrations.",
Arsenic,1019280,"Metallothionein-I/II null mice are more sensitive than wild-type mice to the hepatotoxic and nephrotoxic effects of chronic oral or injected inorganic arsenicals Abstract: Metallothionein (MT) is a low-molecular-weight, sulfhydryl-rich, metal-binding protein that can protect against the toxicity of cadmium, mercury, and copper. However, the role of MT in arsenic (As)-induced toxicity is less certain. To better define the ability of MT to modify As toxicity, MT-I/II knockout (MT-null) mice and the corresponding wild-type mice (WT) were exposed to arsenite [As(III)] or arsenate [As(V)] either through the drinking water for 48 weeks, or through repeated sc injections (5 days/week) for 15 weeks. Chronic As exposure increased tissue MT concentrations (2-5-fold) in the WT but not in MT-null mice. Arsenic by both routes produced damage to the liver (fatty infiltration, inflammation, and focal necrosis) and kidney (tubular cell vacuolization, inflammatory cell infiltration, and interstitial fibrosis) in both MT-null and WT mice. However, in MT-null mice, the pathological lesions were more frequent and severe when compared to WT mice. This was confirmed biochemically, in that, at the higher oral doses of As, blood urea nitrogen (BUN) levels were increased more in MT-null mice (60%) than in WT mice (30%). Chronic As exposures produced 2-10 fold elevation of serum interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha levels, with greater increases seen by repeated injections than by oral exposure, and again, MT-null mice had higher serum cytokines than WT mice after As exposure. Repeated As injections also decreased hepatic glutathione (GSH) by 35%, but GSH-peroxidase and GSH-reductase were minimally affected. MT-null mice were more sensitive than WT mice to the effect of GSH depletion by As(V). Hepatic caspase-3 activity was increased (2-3-fold) in both WT and MT-null mice, indicative of apoptotic cell death. In summary, chronic inorganic As exposure produced injuries to multiple organs, and MT-null mice are generally more susceptible than WT mice to As-induced toxicity regardless of route of exposure, suggesting that MT could be a cellular factor in protecting against chronic As toxicity.",
Arsenic,2088317,"Assessment of trace element contamination in soils around Chinnaeru River Basin, Nalgonda District, India Abstract: Concentrations of trace elements such as As, Ba, Co, Cr, Cu, Ni, Pb, Rb, Sr, V, Y, Zn and Zr were studied in soils to understand metal contamination due to agriculture and geogenic activities in Chinnaeru River Basin, Nalgonda District, India. This area is affected by the geogenic fluoride contamination. The contamination of the soils was assessed on the basis of geoaccumulation index, enrichment factor (EF), contamination factor and degree of contamination. Forty-four soil samples were collected from the agricultural field from the study area from top 10–50 cm layer of soil. Soil samples were analyzed for trace elements using X-ray fluorescence spectrometer. Data revealed that soils in the study area are significantly contaminated, showing high level of toxic elements than normal distribution. The ranges of concentration of Ba (370–1,710 mg/kg), Cr (8.7–543 mg/kg), Cu (7.7–96.6 mg/kg), Ni (5.4–168 mg/kg), Rb (29.6–223 mg/kg), Sr (134–438 mg/kg), Zr (141.2–8,232 mg/kg) and Zn (29–478 mg/kg). The concentration of other elements was similar to the levels in the earth’s crust or pointed to metal depletion in the soil (EF < 1). The high EFs for some trace elements obtained in soil samples show that there is a considerable heavy metal pollution, which could be due to excessive use of fertilizers and pesticides used for agricultural or may be due to natural geogenic processes in the area. Comparative study has been made with other soil-polluted heavy metal areas and its mobility in soil and groundwater has been discussed. A contamination site poses significant environmental hazards for terrestrial and aquatic ecosystems. They are important sources of pollution and may result in ecotoxicological effects on terrestrial, groundwater and aquatic ecosystems.",
Arsenic,1255657,"Photooxidation of arsenite by natural goethite in suspended solution Abstract: Iron and arsenic have been found to coexist in a water environment and the fate of arsenite in the aquatic system is influenced by iron. Goethite is a form of iron hydroxide, which is commonly found in sediments. In previous studies, we have used iron complexes to degrade organic pollutants. Results have shown that some organic pollutants could be totally degraded by iron complexes and our work indicated that iron might cause conversion of arsenic when irradiated. This work attempts to investigate the conversion of arsenite [As(III)] using natural goethite, as the iron source, to quantify the effect of various factors on photooxidation. We also consider the possible mechanism for photooxidation of As(III) using a suspension of natural goethite. The As(III) concentration variation under illumination was compared with the one in the dark to quantify the contribution of light to As(III) oxidation to As(V) in goethite suspended solution. The experiments under N(2) and air atmosphere confirmed the participation of dissolved oxygen. The photooxidation efficiency of As(III) under different conditions was compared to determine the effect of different environmental factors such as pH value, goethite concentration, and humic acid concentration on the photooxidation reaction. In the solution containing 100 ?g L(-1) arsenite and 0.1 g?L(-1) suspended goethite at pH 3.0, nearly 80 % of As(III) was photooxidized after irradiation by a 250-W metal halogen lamp (????313 nm) after 6 h. The effects of initial pH and goethite concentration and humic acid concentration were all examined. The results show that the greatest efficiency of photooxidation of As(III) was at pH 3.0. The extent of photooxidation decreased with increasing goethite concentration and fell sharply in the presence of humic acid under the conditions in this work. Although about 80 % of As(III) was photooxidized after irradiation by a 250-W halogen lamp at pH 3.0 in the presence of goethite suspension, photooxidation was also affected by factors such as pH, concentration of goethite, and presence of humic acid. The scavenger experiments showed that the HO• radical and photogenerated hole are the predominant oxidants in this system responsible for 87.1 % oxidation of As(III), while HO (2) (•) /O (2) (•-) is responsible for 12.9 % oxidation of As(III).",
Arsenic,2347675,"Implementation of zero-valent iron (ZVI) into drinking water supply - Role of the ZVI and biological processes Abstract: Arsenic in drinking water is concerning millions of people around the world, even though many solutions to the problem have come up in recent years. One of the promising solutions for removing arsenic from water is by implementation of a zero-valent iron (ZVI) in the drinking water production. The purpose of this work was to study a treatment of As pollution based on the ZVI, aeration and sand filtration that was monitored for period of 45months. In applied configuration and conditions ZVI was not able to remove arsenic alone, but it worked as a source of ferrous ions that during its oxidation enabled to co-precipitate arsenic compounds in the sand filter. The results show that after a lag phase of about 6months, it was possible to achieve water production with an As content from 20?gL(-1) to below 5?gL(-1). The treatment also enabled to remove phosphates that were present in groundwater and affected As uptake by hindering its co-precipitation with Fe compounds. Determination of colony forming units on As amended agar helped to find arsenic resistant bacteria at each stage of treatment and also in the sand filter backwash sludge. Bacterial communities found in groundwater, containing low concentration of As, were found to have high As resistance. The results also indicate that the lag phase might have been also needed to initiate Fe ions release by corrosion from elemental Fe by help of microbial activity.",
Arsenic,1030727,Soft-particle model analysis of effect of LPS on electrophoretic softness of Acidithiobacillus ferrooxidans grown in presence of different metal ions Abstract: The effect of surface lipopolysaccharides (LPS) on the electrophoretic softness and fixed charge density in the ion-penetrable layer of Acidithiobacillus ferrooxidans cells grown in presence of copper or arsenic ions have been discussed. The electrophoretic mobility data were analyzed using the soft-particle electrophoresis theory. Cell surface potentials of all the strains based on soft-particle theory were lower than those estimated using the conventional Smoluchowski theory. Exposure to metal ions increased the surface electrophoretic softness with decrease in the fixed charge density. Effect of cell surface lipopolysaccharides on the model parameters are investigated and discussed.,
Arsenic,1579373,"Metal Impregnated Silica-Carbon Materials from Rice Husk: A Versatile Sorbent for Toxic Organics and Inorganics in Water and Air Abstract: Carbon bearing materials derived from rice husk (RH) have long been recognized as sorbents for diverse chemicals both organic and inorganic. This work presents an overview of studies demonstrating a single step process of carbonization of chemically pretreated RH to produce metal impregnated silica-carbon char designated as silicarbon materials that can be utilized in sorbing out water-borne organic and inorganic hazardous substances (such as phenol, hexavalent chromium, fluoride, and arsenic) and air-borne volatile organic chemicals (such as acetone, chloroform, benzene, and pyridine). The metal-impregnated silicarbon solids derived from RH appear to constitute renewable, low-cost, user-friendly, and efficient materials for control systems for indoor air contamination and for industrial as well as non-industrial hazardous aqueous pollution.",
Arsenic,1028874,"Dose-dependent disposition of sodium arsenate in mice following acute oral exposure Abstract: The effect of dose on arsenate disposition was studied in adult female B6C3F1 mice, dosed po with 0.5 to 5000 micrograms/kg [73As]-arsenate in water. Urine was collected at 1, 2, 4, 8, 12, 24, and 48 hr and feces at 24 and 48 hr postexposure. The mice were euthanized at 48 hr and tissues were removed. Recovery of arsenate-derived radioactivity ranged from 83 to 89%; 66-79% of the dose was excreted in urine, 10-18% in feces, and &lt; 1% remained in the tissues. Although dose had no effect on the 48-hr excretion of radioactivity, the level of radioactivity in several tissues increased significantly with dose. The urine was analyzed for arsenic metabolites by using ion chromatography to analyze for arsenate, methylarsonic acid (MMA), and dimethylarsinic acid (DMA); ion-pairing high-performance liquid chromatography was used for arsenite analysis. Arsenate elimination ranged from 3 to 15%. DMA was the predominant metabolite excreted (51-64% of dose), but no effect of dose on its elimination was detected. As the dose of arsenate increased, the amount of MMA excreted (0.1-1.0% of dose) significantly increased. At 5000 micrograms/kg arsenate, a significant increase in arsenite excretion was observed. At doses of arsenate &lt; or = 500 micrograms/kg, peak elimination of DMA occurred within 4 hr postexposure. At the 5000 micrograms/kg dose, DMA peak elimination shifted to 8 hr and a lower amount was excreted. In addition, at the 5000 micrograms/kg dose, there was an increase of arsenate and arsenite in the 1- and 2-hr urines. These results suggest that an acute dose of arsenate can affect the metabolism of arsenicals. High doses lead to the accumulation of intermediates that are more reactive than DMA, and this response may lead to increased toxicity.",
Arsenic,1025561,"Vitamin E supplementation protects oxidative stress during arsenic and fluoride antagonism in male mice Abstract: Arsenic and fluoride are common environmental contaminants. Coexposure to these elements can occur through groundwater. We investigated the effects of sodium meta arsenite (50 mg/L in drinking water) and sodium fluoride (50 mg/L in drinking water) individually and in combination. Biochemical parameters suggestive of alterations in heme synthesis pathway, oxidative stress in liver and kidneys, and concentration of essential metals in blood and soft tissues were studied in Swiss albino male mice given the chemicals for 3 weeks. The possible beneficial effect of vitamin E administration (25 mg/kg, oral, alternate days after arsenic/fluoride exposure) on the above variables was investigated. Exposure to arsenic or fluoride caused a significant depletion in blood delta-aminolevulinic acid dehydratase (ALAD) activity, platelet counts (PLT), and glutathione (GSH) level. Blood white blood cell (WBC) counts also decreased. These changes were accompanied by increased reactive oxygen species (ROS) levels. Arsenic and fluoride exposure led to a significant depletion of super oxide dismutase (SOD) activity with no effect on catalase and glutathione peroxidase (GPx) activities. Combined exposure to these toxicants had no synergistic effect on blood ALAD activity and WBC counts, and the effects seen appeared to result predominantly from arsenic. Hepatic catalase activity, on the other hand, increased significantly on exposure to arsenic and fluoride. There was only moderate antagonistic effect on arsenic and fluoride concentration in blood and liver, and kidney arsenic concentration was less pronounced during coexposure compared with arsenic alone. Interestingly, fluoride concentration showed less pronounced uptake during concomitant exposure compared with fluoride exposure alone. Vitamin E supplementation during coexposure to arsenic and fluoride provided only moderate recovery in the altered antioxidant enzymes and in depleting ROS level, but the altered essential metal concentration, particularly calcium level, responded more favorably to vitamin E administration. It can be concluded from the current study that (i) coadministration of arsenic and fluoride was less toxic to the animals compared with individual toxic effects of these toxicants, and (ii) vitamin E supplementation during coexposure had only limited additional beneficial effects in restoring altered biochemical variables, maintaining pro-oxidant/antioxidant balance, and reducing body arsenic store but plays a significant role in maintaining essential metal balance.",
Arsenic,1255634,"Urinary arsenic levels in the French adult population: The French National Nutrition and Health Study, 2006-2007 Abstract: The French Nutrition and Health Survey (ENNS) was conducted to describe dietary intakes, nutritional status, physical activity, and levels of various biomarkers for environmental chemicals (heavy metals and pesticides) in the French population (adults aged 18-74years and children aged 3-17years living in continental France in 2006-2007). The aim of this paper was to describe the distributions of total arsenic and the sum of iAs+MMA+DMA in the general adult population, and to present their main risk factors. In the arsenic study, 1500 and 1515 adults (requested to avoid seafood intake in the previous 3days preceding urine collection) were included respectively for the analysis of the sum of inorganic arsenic (iAs) and its two metabolites, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), and for the total arsenic. Results were presented as geometric means and selected percentiles of urinary arsenic concentrations (?g/L) and creatinine-adjusted urinary arsenic (?g/g of creatinine) for total arsenic, and the sum of inorganic arsenic and metabolites (iAs+MMA+DMA). The geometric mean concentration of the sum of iAs+MMA+DMA in the adult population living in France was 3.34?g/g of creatinine [3.23-3.45] (3.75?g/L [3.61-3.90]) with a 95th percentile of 8.9?g/g of creatinine (10.68?g/L). The geometric mean concentration of total arsenic was 11.96?g/g of creatinine [11.41-12.53] (13.42?g/L [12.77-14.09]) with a 95th percentile of 61.29?g/g of creatinine (72.75?g/L). Urinary concentrations of total arsenic and iAS+MMA+DMA were influenced by sociodemographic and economic factors, and by risk factors such as consumption of seafood products and of wine. In our study, covariate-adjusted geometric means demonstrated several slight differences, due to consumption of fish, shellfish/crustaceans or wine. This study provides the first reference value for arsenic in a representative sample of the French population not particularly exposed to high levels of arsenic (10?g/g of creatinine). It shows that urinary arsenic concentrations in the French adult population (in particular concentrations of iAs+MMA+DMA) were relatively low compared with foreign data.",
Arsenic,1248979,"Curcumin encapsulated in chitosan nanoparticles: A novel strategy for the treatment of arsenic toxicity Abstract: Water-soluble nanoparticles of curcumin were synthesized, characterized and applied as a stable detoxifying agent for arsenic poisoning. Chitosan nanoparticles of less than 50nm in diameter containing curcumin were prepared. The particles were characterized by TEM, DLS and FT-IR. The therapeutic efficacy of the encapsulated curcumin nanoparticles (ECNPs) against arsenic-induced toxicity in rats was investigated. Sodium arsenite (2mg/kg) and ECNPs (1.5 or 15mg/kg) were orally administered to male Wistar rats for 4weeks to evaluate the therapeutic potential of ECNPs in blood and soft tissues. Arsenic significantly decreased blood ?-aminolevulinic acid dehydratase (?-ALAD) activity, reduced glutathione (GSH) and increased blood reactive oxygen species (ROS). These changes were accompanied by increases in hepatic total ROS, oxidized glutathione, and thiobarbituric acid-reactive substance levels. By contrast, hepatic GSH, superoxide dismutase and catalase activities significantly decreased on arsenic exposure, indicative of oxidative stress. Brain biogenic amines (dopamine, norepinephrine and 5-hydroxytryptamine) levels also showed significant changes on arsenic exposure. Co-administration of ECNPs provided pronounced beneficial effects on the adverse changes in oxidative stress parameters induced by arsenic. The results indicate that ECNPs have better antioxidant and chelating potential (even at the lower dose of 1.5mg/kg) compared to free curcumin at 15mg/kg. The significant neurochemical and immunohistochemical protection afforded by ECNPs indicates their neuroprotective efficacy. The formulation provides a novel therapeutic regime for preventing arsenic toxicity.",
Arsenic,180230,"Water arsenic exposure and children's intellectual function in Araihazar, Bangladesh Abstract: Exposure to arsenic has long been known to have neurologic consequences in adults, but to date there are no well-controlled studies in children. We report results of a cross-sectional investigation of intellectual function in 201 children 10 years of age whose parents participate in our ongoing prospective cohort study examining health effects of As exposure in 12,000 residents of Araihazar, Bangladesh. Water As and manganese concentrations of tube wells at each child’s home were obtained by surveying all wells in the study region. Children and mothers came to our field clinic, where children received a medical examination in which weight, height, and head circumference were measured. Children’s intellectual function on tests drawn from the Wechsler Intelligence Scale for Children, version III, was assessed by summing weighted items across domains to create Verbal, Performance, and Full-Scale raw scores. Children provided urine specimens for measuring urinary As and creatinine and were asked to provide blood samples for measuring blood lead and hemoglobin concentrations. Exposure to As from drinking water was associated with reduced intellectual function after adjustment for sociodemographic covariates and water Mn. Water As was associated with reduced intellectual function, in a dose–response manner, such that children with water As levels > 50 ?g/L achieved significantly lower Performance and Full-Scale scores than did children with water As levels < 5.5 ?g/L. The association was generally stronger for well-water As than for urinary As.",
Arsenic,2278834,"Clinical and epidemiological features of textile contact dermatitis:an Italian multicentre study Abstract: <strong>BACKGROUND: </strong>The prevalence of occupational and non-occupational textile dermatitis seems to be increasing, probably because of changed textile manufacturing techniques.<br /><br /><strong>OBJECTIVE: </strong>Evaluation of the clinical features and epidemiology of textile contact dermatitis (TCD) in Italy.<br /><br /><strong>METHODS: </strong>Demographic data, clinical history aspects, atopy and positive patch test reactions to occupational and non-occupational allergens were investigated in 277 textile dermatitis patients.<br /><br /><strong>RESULTS: </strong>Contact dermatitis was the most frequent clinical presentation (95.3%). TCD was more common in females, in the fourth to fifth decades of life, and in atopic dermatitis patients. The lesions were prevalently eczematous (74.2%), and mostly located on the trunk and lower limbs in non-occupational cases, and on the hands in textile workers. Allergic TCD (58.3%) was more frequent than irritant TCD. The dyes (Disperse Blue 124, Disperse Blue 106, and Disperse Yellow 3) were most frequently responsible (79.8%), especially in non-occupational TCD. Formaldehyde and resins were more important in occupational TCD. Concomitant reactions among textile dyes and/or finishing resins were observed in 50.0% of patients.<br /><br /><strong>CONCLUSIONS: </strong>Some strategies (sensitization potential of new textile chemicals, more stable dyes, reduced levels of formaldehyde in clothing, and collaboration with textile industry and trade associations) should be adopted to decrease the TCD incidence and update the textile patch testing series.",
Arsenic,1340065,"Heterologously expressed arsenite oxidase: A system to study biogenesis and structure/function relationships of the enzyme family Abstract: Studies of native arsenite oxidases from Ralstonia sp. S22 and Rhizobium sp. NT-26 raised two major questions. The first one concerns the mode of the enzyme's membrane-association. It has been suggested that a hypothetical not conserved protein could account for this variable association. Expression of the wild type arsenite oxidase in Escherichia coli allowed us to study the cellular localization of this enzyme in the absence of such a hypothetical partner. The results with the Ralstonia sp. S22 enzyme suggest that no additional protein is required for membrane association. The second question addresses the influence of the disulfide bridge in the small Rieske subunit, conspicuously absent in the Rhizobium sp. NT-26 enzyme, on the properties of the [2Fe-2S] center. The disulfide bridge is considered to be formed only after translocation of the enzyme to the periplasm. To address this question we thus first expressed the enzyme in the absence of its Twin-arginine translocation signal sequence. The spectral and redox properties of the cytoplasmic enzyme are unchanged compared to the periplasmic one. We finally studied a disulfide bridge mutant, Cys106Ala, devoid of the first Cys involved in the disulfide bridge formation. This mutation, proposed to have a strong effect on redox and catalytic properties of the Rieske protein in Rieske/cytb complexes, had no significant effect on properties of the Rieske protein from arsenite oxidase. Our present results demonstrate that the effects attributed to the disulfide bridge in the Rieske/cytb complexes are likely to be secondary effects due to conformational changes.",
Arsenic,1024705,"The nitric oxide prodrug, V-PYRRO/NO, mitigates arsenic-induced liver cell toxicity and apoptosis Abstract: Arsenite is an important cancer chemotherapeutic. The liver is a major target tissue of arsenic toxicity and hepatotoxicity may limit its chemotherapeutic efficacy. O(2)-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO) is a liver-selective nitric oxide (NO)-producing prodrug metabolized by hepatic P450 enzymes to release NO locally. V-PYRRO/NO protects against various organic or inorganic hepatotoxicants but any role in arsenic hepatotoxicity is undefined. Thus, we studied the effects of V-PYRRO/NO (0-1000muM) pretreatment on inorganic arsenic-induced toxicity in cultured rat liver (TRL 1215) cells. These cells metabolized the prodrug to release NO, producing extracellular nitrite levels to 41.7-fold above control levels (7.50+/-0.38 microM) after 24h V-PYRRO/NO (1000 microM) exposure. The effect of pretreatment with V-PYRRO/NO (24h) on the cytolethality of arsenic (as NaAsO(2)) exposure (24h) was assessed. Arsenic was markedly less toxic in V-PYRRO/NO pretreated cells (LC(50)=30.3 microM) compared to control (LC(50)=20.1 microM) and the increases in LC(50) showed a direct relationship to the level of NO produced (measured as nitrite). Consistent with the cytolethality data, V-PYRRO/NO pretreatment markedly reduced arsenic-induced apoptosis as assessed by DNA fragmentation. Activation of the c-Jun N-terminal kinase (JNK) pathway can be critical to apoptosis and pretreatment with V-PYRRO/NO suppressed arsenic-induced JNK activation. V-PYRRO/NO pretreatment modestly increased metallothionein (MT), a metal-binding protein, but greatly enhanced arsenic induction of MT. Thus, V-PYRRO/NO pretreatment directly mitigates arsenic toxicity in cultured liver cells, reducing cytolethality, apoptosis and related JNK pathway activation, apparently through generation of NO. The role of NO in reducing the hepatotoxicity of arsenical chemotherapeutics in vivo deserves additional study.",
Arsenic,1519172,"A comparative analyses of morphological variations, phagocytosis and generation of cytotoxic agents in flow cytometrically isolated hemocytes of Indian molluscs Abstract: A comparative analyses of hemocytes of molluscs, Pila globosa (Gastropoda: Prosobranchia), Bellamya bengalensis (Gastropoda: Prosobranchia) and Lamellidens marginalis (Bivalvia: Eulamellibranchiata) were carried out for morphotype and subpopulation identification, analyses of phagocytosis and generation of cytotoxic agents. Flow cytometry and microscopic analyses of hemocytes revealed the existence of agranulocytes (blast like cells, round hyalinocytes and spindle hyalinocytes), semigranulocytes (semigranular asterocytes and round semigranulocytes) and granulocytes (round granulocytes, spindle granulocytes and granular asterocytes) as three morphotypes. In P. globosa, granulocytes and semigranulocytes and in B. bengalensis granulocytes and agranulocytes are the chief phagocytes and major producers of superoxide anion and nitric oxide. In L. marginalis, granulocytes were identified as principal phagocytes with prominent activity of superoxide anion and nitric oxide. Highest activity of phenoloxidase was recorded in the agranulocytes of P. globosa with moderate activities among other morphotypes of all three species. Differential result may be due to species specific response, non-identical habitat preference and related adaptation of the species to their different ecological niches.",
Arsenic,2345660,"Midazolam and propofol used alone or sequentially for long-term sedation in critically ill, mechanically ventilated patients: A prospective, randomized study Abstract: INTRODUCTION: Midazolam and propofol used alone for long-term sedation are associated with adverse effects. Sequential use may reduce the adverse effects, and lead to faster recovery, earlier extubation and lower costs. This study evaluates the effects, safety, and cost of midazolam, propofol, and their sequential use for long-term sedation in critically ill mechanically ventilated patients. METHODS: A total of 135 patients who required mechanical ventilation for >3 days were randomly assigned to receive midazolam (group M), propofol (group P), or sequential use of both (group M-P). In group M-P, midazolam was switched to propofol until the patients passed the spontaneous breathing trial (SBT) safety screen. The primary endpoints included recovery time, extubation time and mechanical ventilation time. The secondary endpoints were pharmaceutical cost, total cost of ICU stay, and recollection to mechanical ventilation-related events. RESULTS: The incidence of agitation following cessation of sedation in group M-P was lower than group M (19.4% versus 48.7%, P = 0.01). The mean percentage of adequate sedation and duration of sedation were similar in the three groups. The recovery time, extubation time and mechanical ventilation time of group M were 58.0 (interquartile range (IQR), 39.0) hours, 45.0 (IQR, 24.5) hours, and 192.0 (IQR, 124.0) hours, respectively; these were significantly longer than the other groups, while they were similar between the other two groups. In the treatment-received analysis, ICU duration was longer in group M than group M-P (P = 0.016). Using an intention-to-treat analysis and a treatment-received analysis, respectively, the pharmaceutical cost of group M-P was lower than group P (P < 0.01) and its ICU cost was lower than group M (P < 0.01; P = 0.015). The proportion of group M-P with unbearable memory of the uncomfortable events was lower than in group M (11.7% versus 25.0%, P < 0.01), while the proportion with no memory was similar (P > 0.05). The incidence of hypotension in group M-P was lower than group P ( P = 0.01). CONCLUSION: Sequential use of midazolam and propofol was a safe and effective sedation protocol, with higher clinical effectiveness and better cost-benefit ratio than midazolam or propofol used alone, for long-term sedation of critically ill mechanically ventilated patients.",
Arsenic,1354115,Comparative Study of the Adsorption Selectivity of Cr(VI) onto Cationic Hydrogels with Different Functional Groups Abstract: ,
Arsenic,1019247,"Acute toxicity of arsenic to three species of New Zealand Chironomids: Chironomus zealandicus, Chironomus sp. a and Polypedilum pavidus (Diptera, Chironomidae) Abstract: Accute toxicity tests are important in establishing appropriate water quality criteria and standards. It is important that the most sensitive life stage should be used in toxicity tests to properly estimate the sensitivity of the test animal and to make toxicity tests ecologically relevant (Williams et al. 1986). Many invertabrates including crustaceans, molluscs, and insects have been used as biotoxicity test organisms. However, the most widespread organisms used in toxicity tests have benn genera of the family Chironomidae (Insecta: Diptera). Although different species of chironomid have frequently been used in acute toxicity tests, many of these tests have evaluated the sensitivity of only one stage of the life cycle, usually the 4th instar larvae. Dave available for chironomids (Gauss et al. 1985; Williams et al. 1986) however, suggest that earlier life stages are more sensitive than later ones. The common components of the benthos at many lakes in the central North Island of New Zealand are chironomids. The most common representatives of chironomids in these lakes are Chironomus zealandicus (Hudson), Chironomus sp a and Polypedilum pavidus (Hutton). Arsenic enters the aquatic environment from a variety of natural and industrial sources and is generally regarded as highly toxic to all components of aquatic communities. However, relatively little work has been carried out on the toxicity of arsenic to freshwater macroinvertabrates. In New Zealand, dominant sources of As input into waterways are geothermal activity, herbicides and timber preservatives. The objective of the present study was to investigate how the sensitivity of C. zealandicus, C. sp. a and P. pavidus vary with biological and non-biological facotors such as age, source system, sampling season, test temperature, and the valency state of arsenic.",
Arsenic,1347390,"Arsenite stabilizes I kappa B alpha and prevents NF-kappa B activation in IL-1 beta-stimulated Caco-2 cells independent of the heat shock response Abstract: Recent studies suggest that sodium arsenite downregulates NF-kappaB activity by inhibiting phosphorylation and subsequent degradation of IkappaBalpha. Many effects of sodium arsenite are secondary to induction of heat shock proteins. The role of the heat shock response in arsenite-induced inhibition of NF-kappaB, however, is not known. We examined the involvement of the heat shock response in arsenite-induced inhibition of NF-kappaB activity in IL-1beta-stimulated Caco-2 cells, a human colorectal adenocarcinoma cell line with enterocytic properties. Treatment of the cells with IL-1beta resulted in increased IkappaB kinase activity, reduced levels of IkappaBalpha and increased NF-kappaB DNA binding activity. Sodium arsenite blocked all of these responses to IL-1beta without inducing changes in heat shock factor activity or heat shock protein levels. Results from additional experiments showed that the protective effect of sodium arsenite on IkappaBalpha was not influenced by the oxygen radical scavenger catalase or by inhibitors of the MAP-kinase signaling pathway. The present results suggest that sodium arsenite stabilizes IkappaBalpha and prevents NF-kappaB activation in IL-1beta-stimulated Caco-2 cells independent of the heat shock response. In addition, stabilization of IkappaBalpha by sodium arsenite does not require oxygen radical formation or activation of the MAP kinase signaling pathway.",
Arsenic,1339965,"Arsenic distribution and speciation in Daphnia pulex Abstract: Rat Lake, Yellowknife, Northwest Territories, is situated on arsenic-rich tailings from a historical gold mine. The abundant zooplankton species Daphnia pulex in this lake was used to study the impact of arsenic at the base of the freshwater food web; the speciation and distribution of arsenic in D. pulex and its food sources; and the origin of formation of organoarsenicals in freshwater systems. The arsenic concentration in lake water was measured as 0.25 mg L(-1), while the zooplankton organisms contained up to 35 mg kg(-1) d.w. arsenic. Plankton samples were analyzed for arsenic speciation, by using X-ray Absorption Near Edge Structure (XANES) on the whole, dried samples and High Performance Liquid Chromatography coupled to Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) on water extracts. XANES data suggest that D. pulex mainly contain inorganic arsenicals with 56% of arsenic with +5 oxidation state and 10% of arsenic with +3 oxidation state, but also 34% of organoarsenic compounds that were identified with HPLC-ICP-MS as monomethylarsonate (MMA), dimethylarsinate (DMA), and arsenosugars. The most abundant of the organoarsenicals was the glycerol sugar (Sugar 1). X-ray Fluorescence (XRF) mapping of D. pulex for arsenic distribution showed that arsenic was mainly distributed in the gut of the animal, where its concentration was ten times higher than in the surrounding tissues. Moreover, the analysis of residues from extractions targeting water-soluble and lipid-soluble arsenicals suggested that part of the measured arsenic signal comes from ingested sediments, phytoplankton, or other food sources. These food sources contain inorganic arsenic only, with As(V)-O in phytoplankton and As(III)-S in sediments, suggesting the possibility that the organoarsenicals compounds detected in the tissues of the organism are created by the Daphnia.",
Arsenic,839208,"Determination of arsenic in scalp hair samples from exposed subjects using microwave-assisted digestion with and without enrichment based on cloud point extraction by electrothermal atomic absorption spectrometry Abstract: A simple and rapid cloud point extraction (CPE) procedure was applied for preconcentration of trace quantities of arsenic (As) in scalp hair samples. The samples were subjected to microwave-assisted digestion in a mixture of nitric acid and hydrogen peroxide (2 + 1, v/v) prior to preconcentration by CPE. The As in digested samples was complexed with ammonium pyrrolidine dithiocarbamate (APDC), and the resultant As-PDC complex was extracted by a nonionic surfactant, octylphenoxypolyethoxyethanol (Triton X-114). After centrifugation, the surfactant-rich phase was diluted with 0.1 M HNO3 in methanol and analyzed by electrothermal atomic absorption spectrometry. The experimental parameters, i.e., amount of APDC, concentration of Triton X-114, equilibrium temperature and time, were optimized. For validation of the proposed method, a certified reference material (CRM) of human hair (BCR 397) was used. No significant difference (P &gt; 0.05) was observed between the experimental results and certified values of the CRM (paired t-test). The LOD and LOQ obtained under the optimal conditions were 0.025 and 0.083 microg/kg, respectively. The developed method was applied for the determination of As in scalp hair samples from male and female subjects of two villages of Khairpur Mir's, Pakistan.",
Arsenic,1508579,"Comprehensive Analysis of Lipophilic Arsenic Species in a Brown Alga (Saccharina latissima) Abstract: Approaches for the unambiguous identification of lipophilic arsenic species in Saccharina latissima (sugar kelp) have been studied. Parallel use of high resolution ICPMS and electrospray ionization (ESI)-MS after separation revealed that Saccharina latissima contained three distinct classes of lipophilic As-species, a family of arsenic containing phospholipids (AsPL), all including As in the form of As-sugar-PO(4), As-containing hydrocarbons (AsHC), and As-containing polyunsaturated fatty acids (AsFA). For detailed identification, the use of phospholipases, in particular phospholipase A2, was essential to define the fatty acid composition (determination of regioisomers) of the lipids without purification of the sample, while fragmentation of the molecules by MS(2) measurements alone did not supply this information. Some of the identified AsPL contained unsaturated fatty acids (C16:1, C18:1 to C18:3), but saturated fatty acids dominated the AsPL. The fatty acid bound to the position 2? was predominantly C16:0. Complete lipid hydrolysis showed that this alga did not contain arsenic containing fatty acids (AsFA) bound to complex lipids. Our investigations indicate that in addition to RP-HPLC-ICPMS/ESI-MS a range of different derivatization methods should be used for the comprehensive identification of unknown lipid-soluble arsenic compounds.",
Arsenic,2149082,"Kinetics of arsenite oxidation by Variovorax sp. MM-1 isolated from a soil and identification of arsenite oxidase gene Abstract: A Gram-negative, arsenite-oxidizing bacterial strain, MM-1 tolerant to 20mM arsenite and 200mM arsenate was isolated from a heavy metal contaminated soil which contained only 8.8mgkg(-1) of arsenic. Based on 16S rRNA analysis, the strain was closely related to the genus Variovorax. This strain completely oxidized 500?M of arsenite to arsenate within 3h of incubation in minimal salts medium. Kinetic studies of arsenite oxidation by the cells showed one of the lowest Km (17?M) and highest Vmax (1.23×10(-7)?Mmin(-1)cell(-1)) values reported to date for whole cell suspension. PCR analysis using degenerate primers confirmed the presence of arsenite oxidase gene and its amino acid sequence was 70-91% identical to the large subunit of most reported arsenite oxidases. The significant arsenite oxidation capacity shown by the strain opens the way to its potential application in arsenic remediation process.",
Arsenic,627141,"Metal attraction: An ironclad solution to arsenic contamination? Abstract: Inorganic arsenic-the more acutely toxic form of this metalloid element-contaminates drinking water supplies around the world. In the United States, the most serious arsenic contamination occurs in the West, Midwest, Southwest, and Northeast; as many as 20 million people-many getting their water from unregulated private wells-may be exposed to excess arsenic in their drinking water. In Bangladesh, it's estimated that as many as 40 million people may be suffering from arsenic poisoning; contaminated drinking water is also a problem in many other countries, including Argentina, China, Chile, Ghana, Hungary, India, and Mexico.",
Arsenic,1332282,"Stressor-Specific Activation of Heat Shock Genes in H35 Rat Hepatoma Cells Abstract: Responses of Reuber H35 hepatoma cells exposed to increasing doses of heat, arsenite ions, or cadmium ions were investigated. Doses which are capable of activating the heat shock transcription factor (HSF) were determined. The activity of this factor in the poststress period was correlated to the recovery of total protein synthesis in this same period. Subsequently, increases of mRNA levels and rates of synthesis of heat shock protein (HSP)60, HSP68, and HSP84 after exposure to the stressors were determined. We generally found that the rate of HSP synthesis correlated well with HSP mRNA levels, supporting the idea that the stress response is regulated mainly at the transcriptional level. A stressor-specific pattern of HSP mRNA induction can be observed. The most striking example is cadmium chloride which does not induce HSP60 nor its mRNA. Interestingly, under these conditions maximal activation of HSF is observed. Therefore, we conclude that more processes than just HSF activations are involved in the induction of heat shock genes.",
Arsenic,1019265,"DNA damage in arsenite- and cadmium-treated bovine aortic endothelial cells Abstract: Reactive oxygen species have been shown to be involved in the mutagenicity, clastogenicity, and apoptosis of mammalian cells treated with arsenic or cadmium. As these endpoints require several hours of cellular processing, it is not clear that reactive oxygen species damage DNA directly or interfere with DNA replication and repair. Using single-cell alkaline electrophoresis, we have detected DNA strand breaks (DSBs) in bovine aortic endothelial cells by a 4-h treatment with sodium arsenite (As) and cadmium chloride (Cd) in sublethal concentrations. As-induced DSBs could be decreased by nitric oxide (NO) synthase inhibitors, superoxide scavengers, and peroxynitrite scavengers and could be increased by superoxide generators and NO generators. Treatment with As also increased nitrite production. These results suggest that As-increased NO may react with O2*- to produce peroxynitrite and cause DNA damage. The results showing that Cd increased cellular H2O2 levels and that Cd-induced DSBs could be modulated by various oxidant modulators suggest that Cd may induce DSBs via O2*-, H2O2, and *OH. Nevertheless, the DSBs in both As- and Cd-treated cells seem to come from the excision of oxidized bases such as formamidopyrimidine and 8-oxoguanine, as the Escherichia coli enzyme formamidopyrimidine-DNA glycosylase (Fpg) increased DSBs in cells treated with As, 3-morpholinosydnonimine (a peroxynitrite-generating agent), Cd, or H2O2.",
Arsenic,2064245,"Genotoxic effect of exposure to metal(loid)s. A molecular epidemiology survey of populations living and working in Panasqueira mine area, Portugal Abstract: Previous studies investigating the exposure to metal(loid)s of populations living in the Panasqueira mine area of central Portugal found a higher internal dose of elements such as arsenic, chromium, lead, manganese, molybdenum and zinc in exposed individuals. The aims of the present study were to evaluate the extent of genotoxic damage caused by environmental and occupational exposure in individuals previously tested for metal(loid) levels in different biological matrices, and the possible modulating role of genetic polymorphisms involved in metabolism and DNA repair. T-cell receptor mutation assay, comet assay, micronucleus (MN) test and chromosomal aberrations (CA) were performed in a group of 122 subjects working in the Panasqueira mine or living in the same region. The modifying effect of polymorphisms in GSTA2, GSTM1, GSTP1, GSTT1, XRCC1, APEX1, MPG, MUTYH, OGG1, PARP1, PARP4, ERCC1, ERCC4, and ERCC5 genes was investigated. Significant increases in the frequency of all biomarkers investigated were found in exposed groups, however those environmentally exposed were generally higher. Significant influences of polymorphisms were observed for GSTM1 deletion and OGG1 rs1052133 on CA frequencies, APEX1 rs1130409 on DNA damage, ERCC1 rs3212986 on DNA damage and CA frequency, and ERCC4 rs1800067 on MN and CA frequencies. Our results show that the metal(loid) contamination in the Panasqueira mine area induced genotoxic damage both in individuals working in the mine or living in the area. The observed effects are closely associated to the internal exposure dose, and are more evident in susceptible genotypes. The urgent intervention of authorities is required to protect exposed populations.",
Arsenic,1030717,"Arsenic uptake by two vegetables grown in two soils amended with As-bearing animal manures Abstract: Organoarsenicals are widely used as growth promoters in animal feed, resulting in unabsorbed arsenic (As) left in animal manures. A pot experiment was conducted to investigate the growth and As uptake of amaranth (Amaranthus tricolor Linn, a crop with an axial root system) and water spinach (Ipomoea aquatica Forsk, a crop with a fibrous root system) grown in a paddy soil (PS) and a lateritic red soil (LRS) amended with 2% and 4% (w/w) As-bearing chicken manure and pig manure, respectively. Soils without any fertilizers were the controls. The biomass, As contents and total As uptake of the shoots, As transfer factors (TFs) from roots to shoots and the root/shoot (R/S) ratios of water spinach were significantly higher than those of amaranth (p&lt;0.0015). The biomass, total As uptake and R/S ratios showed significant difference for soil types (p&lt;0.0031). Manure amendments increased the biomass of both vegetables, reduced the As contents in amaranth but increased those in water spinach. The As contents were negatively correlated with the biomass in amaranth, but positive correlation was observed for water spinach. The total As uptake by amaranth was decreased in PS and insignificantly affected in LRS by manure application, but that by water spinach was significantly increased in both soils. We suggest that the higher As uptake by water spinach might be related to its root structure and R/S ratio. Heavy application of As-bearing animal manures should be avoided in water spinach.",
Arsenic,2088512,"Characterization of the cytosolic distribution of priority pollutant metals and metalloids in the digestive gland cytosol of marine mussels: Seasonal and spatial variability Abstract: Cytosolic profiles of several priority pollutant metals (Cu, Cd, Zn, Pb) and metalloid As were analyzed in the digestive gland of the mussel (Mytilus galloprovincialis) sampled at locations with different environmental pollution levels along the Croatian coast in the spring and summer season. Size-exclusion chromatography (SEC) connected to inductively coupled plasma mass spectrometry (ICP-MS) was used to determine selected elements bound to cytosolic biomolecules separated based on their molecular size. Copper, cadmium and zinc eluted mostly associated with high molecular weight (HMW) and medium molecular weight (MMW) biomolecules, but with a more prominent elution in the MMW peak at polluted locations which were probably associated with the 20kDa metallothionein (MT). Elution of all three metals within this peak was also strongly correlated with cytosolic Cd as strong inducer of MT. Lead mostly eluted in HMW biomolecule range, but in elevated cytosolic Pb concentrations, significant amount eluted in low molecular weight (LMW) biomolecules. Arsenic, on the other hand eluted almost completely in LMW range, but we could not distinguish specific molecular weight biomolecules which would be predominant in detoxification mechanism. Seasonal variability in element abundance within specific peaks was present, although not in the same extent, for all elements and locations, especially for As. The results confirm the suitability of the distribution of selected metals/metalloids among different cytosolic ligands as potential indicator for metal exposure. Obtained findings can also serve as guidelines for further separation and characterization of specific cytosolic metal-binding biomolecules.",
Arsenic,1019917,"Arsenite methylation by methylvitamin B12 and glutathione does not require an enzyme Abstract: Although inorganic arsenic is methylated enzymatically by arsenic methyltransferases, which have been found in many mammalian livers, the detection of such enzymes has not been successful in surgically removed human livers. Results of the present experiments demonstrated that methylvitamin B12 (methylcobalamin, CH3B12) in the presence of thiols and inorganic arsenite can produce, in vitro, substantial amounts of monomethylarsonic acid (MMA) and small amounts of dimethylarsinic acid (DMA) in the absence of enzymes. Furthermore, this nonenzymatic methylation of inorganic arsenite by CH3B12 was increased substantially by the presence of dimercaptopropanesulfonate (DMPS) and/or sodium selenite. The actions of DMPS and selenite together were additive. The methylation by CH3B12 was neither inhibited nor stimulated by human liver cytosol. Since the amount of MMA produced by the in vitro system described in this study was not small, these results emphasize the need for a properly designed nutritional study in humans exposed to inorganic arsenic as to the relationship between vitamin B12, selenium, and the metabolism of carcinogenic inorganic arsenic.",
Arsenic,627154,"The effect of estradiol on the oxidative damage and trace element level determined in the liver of rats treated with dimethylarsinic acid Abstract: DMA--dimethylarsinic acid (cacodylic acid)--used as an herbicide, is the major metabolite formed after the exposure to inorganic arsenics in mammals. It is considered to have an important role in arsenic carcinogenesis through the induction of oxidative damage in various tissues. Estradiol, apart from its main hormonal effect, displays both prooxidative and antioxidative action depending on the condition of the treatment. The oxidative stress plays a crucial role in estrogen-induced carcinogenesis. In the experiments performed in female Wistar rats receiving drinking water ad libitum with 0.01% DMA for 10 weeks, one half of rats was treated with 17beta-estradiol (0.1 mg/rat s.c., twice a week) starting the 3rd week. One more group received estradiol only and last group served as controls receiving drinking water without treatment. The DMA enhanced lipid peroxidation in the liver, estradiol treatment potentiated this effect of arsenic. The GSH level was enhanced in DMA+estradiol treated group. In estradiol-only treated group both the lipid peroxidation and GSH content were increased. The administration of estradiol caused an enhancement of several trace element concentrations in the liver, mainly that of iron and copper. The critical role of estrogen on the development of oxidative stress was thus proved.",
Arsenic,2298676,"Evaluation of arsenate content of rice and rice bran purchased from local markets in the People's Republic of China Abstract: In previous studies, inorganic arsenic and total arsenic concentrations in rice bran have been much higher than those in polished rice obtained from the same whole paddy rice. However, the arsenic species distribution between rice and bran is still unknown, especially for arsenite (AsIII) and arsenate (AsV). To characterize the arsenic species in rice and bran and explain the elevated concentrations of inorganic arsenic and total arsenic, four arsenic species, AsIII, AsV, dimethylarsinic acid, and monomethylarsonic acid, were evaluated. Rice and bran samples (n = 108) purchased from local markets in the People's Republic of China were analyzed using high-performance liquid chromatography with hydride generation and atomic fluorescence spectrometry and then microwave extraction. As expected, most of the arsenic was found in bran, with bran/rice ratios of 6.8 for total arsenic species and 6.4 for inorganic arsenic. Among four arsenic species, the maximum bran/rice ratio was 104.7 (335/3.2 ?g kg(-1)) for AsV followed by 1.2 (69.2/56.1) for AsIII, 1.3 (6.7/5.2) for dimethylarsinic acid, and 4.0 (0.8/0.2) for monomethylarsonic acid. Thus, the large difference in arsenic concentration between rice and bran was mostly due to the difference in the AsV concentration, which account for 96 and 95 % of the difference for total arsenic species and inorganic arsenic, respectively. Therefore, the possibility of AsV contamination in rice bran and its by-products needs more study. This study is the first in which concentrations of AsIII and AsV in rice and bran have been documented, revealing that a higher percentage of AsV occurs in bran than in rice.",
Arsenic,1347247,"Dimethylarsinous acid disturbs cytokinesis Abstract: Dimethylarsinous acid (DMAIII) induced tetraploidy and multinucleation in V79 cells. While the highest yield of tetraploids and multinucleated cells was at 1.25 microM of DMAIII, the mitotic index was highest at DMAIII 2.5 microM due to mitotic arrest. Mitosis was not observed at 5 microM. We observed V79 cells treated with DMAIII and visualized with rhodamine-phalloidin. Abnormal actin location was observed in the dividing cells which were treated with DMAIII and visualized with rhodamine-phalloidin. These findings suggested strongly that DMAIII inhibits not only formation of the normal mitotic spindle but cytokinesis and induces the formation of multinuclear cells.",
Arsenic,1797844,"A modified sequential extraction method for arsenic fractionation in sediments Abstract: A modified sequential extraction method was developed to characterize arsenic (As) associated with different solid constituents in surficial deposits (sediments), which are unconsolidated glacial deposits overlying bedrock. Current sequential extraction methods produce a significant amount of unresolved As in the residual fraction, but our proposed scheme can fractionate >90% of the As present in sediments. Sediment samples containing different As concentrations (3-35?gg(-1)) were used to assess the developed method. The pooled amount of As recovered from all the fractions using the developed method was similar (83-122%) to the total As extracted by acid digestion. The concentrations of As in different fractions using the developed scheme were comparable (89-106%) to the As fractions obtained by other existing methods. The developed method was also evaluated for the sequential extraction of other metals such as copper (Cu), cobalt (Co), chromium (Cr) and strontium (Sr) in the sediment samples. The pooled concentrations of these four individual metals from all the fractions were similar (96-104%) to their total concentrations extracted by acid digestion. During method development, we used extractants that did not contain chloride to eliminate formation of polyatomic ions of argon chloride ((40)Ar(35)Cl) that interfered with (75)As when analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The results suggest that the developed method can reliably be employed for complete As and other metals' fractionation in sediments using ICP-MS.",
Arsenic,1024467,"Arsenic interferes with the signaling transduction pathway of T cell receptor activation by increasing basal and induced phosphorylation of Lck and Fyn in spleen cells Abstract: Arsenic is known to produce inhibition as well as induction of immune cells proliferative responses depending on the doses as one of its mechanisms of immunotoxicity. Here we evaluate the effect of arsenic exposure on the activation of splenic mononuclear cells (SMC) in male CD57BL6N mice. Intra-gastric exposure to arsenic (as sodium arsenite) for 30 days (1, 0.1, or 0.01 mg/kg/day), reduced the proportion of CD4+ cells and the CD4+/CD8+ ratio in the spleen, increasing the proportion of CD11b+ cells. Arsenic exposure did not modify the proportion of B cells. SMC showed an increased level of phosphorylation of lck and fyn kinases (first kinases associated to TCR complex when activated). Although normal levels of apoptosis were observed on freshly isolated SMC, an increase in apoptotic cells related with the increase in phosphorylation of lck and fyn was observed when SMC were activated with Concanavalin-A (Con-A). Arsenic exposure reduced the proliferative response of SMC to Con-A, and also reduced secretion of IL-2, IL-6, IL-12 and IFNgamma. No effect was observed on IL-4, and IL-10 secretion. The same effects were observed when SMC of exposed animals were activated with anti-CD3/CD28 antibodies for 24 h, but these effects were transitory since a recovery, up to control levels or even higher, were observed after 72 h of stimulation. This study demonstrates that repeated and prolonged exposure to arsenic alters cell populations and produces functional changes depending on the specific activation pathway, and could be related with the phosphorylation status of lck and fyn kinases.",
Arsenic,627258,"Arsenic-induced genotoxic and cytotoxic effects in human keratinocytes, melanocytes and dendritic cells Abstract: Arsenical keratosis and skin cancer are among the most common health effects associated with acute and chronic exposures to arsenic. This study examines the acute and chronic dose-responses of arsenic in established human cell lines using keratinocytes (HaCaT), melanocytes (CRL1675) and dendritic cells (THP-1 + A23187). Chronic conditions were established by treating the three cell lines with at least 8 passages in 0.2 microg/mL arsenic trioxide. Cytotoxicity was assessed using the fluorescein diacetate assay after 72 hrs of exposure. Single cell gel electrophoresis (Comet assay) was used to measure DNA damage. Acute exposure to arsenic had LD10 and LD25 values of 0.38 microg/mL and 3.0 microg/mL for keratinocytes; 0.19 microg/mL and 0.38 microg/mL for melanocytes; and 0.38 microg/mL and 0.75 microg/mL for dendritic cells. Cytotoxicity assays for chronically exposed cells resulted in LD10, and LD25 values of 0.4 microg/mL and 0.8 microg/mL for keratinocytes; 0.10 microg/mL and 0.20 microg/mL for melanocytes; and 0.10 microg/mL and 1.0 microg/mL for dendritic cells. The Comet assay showed that arsenic was highly genotoxic to the three cell lines. No significant differences (p > 0.05) in DNA cleavage were observed between acute and chronic exposures. In acute exposure arsenic genotoxicity was more severe with dendritic cells while melanocytes were more sensitive to arsenic cytotoxicity. Similarly, chronically exposed dendritic cells showed the maximum genotoxic damage while melanocytes were more sensitive to arsenic cytotoxicity. In conclusion, this research shows that arsenic is dermatotoxic, showing a high degree of genotoxicity and cytotoxicity to skin cells.",
Arsenic,1028750,"Mutational spectrum in the p53 gene in bladder tumors from the endemic area of black foot disease in Taiwan Abstract: An elevated risk of bladder cancer has been reported in the endemic region of 'black foot disease' on the southwest coast of Taiwan and may be related to high arsenic levels in artesian well water. Thirteen urothelial tumors from this endemic region were examined for mutations in exons 5-8 of the p53 gene to identify the effects of possible exogenous factors at the DNA level. DNA was extracted from archival tissue after microdissection of tumors and analyzed by PCR-SSCP (polymerase chain reaction-based single strand conformation polymorphism), followed by direct sequencing. Eight cases (62%) showed mutations and 9 of the 10 point mutations observed were transitions. The type and position of the mutations were not significantly different when compared with the spectra of p53 mutations previously reported for transitional cell carcinomas (TCCs). However, two of the mutations were CGC--&gt;CAC base changes at codon 175, a mutational hotspot for many tumor types but previously unreported in TCCs except in cases associated with inflammatory agents. Three of the tumors examined were found to contain double mutations, a relatively rare mutagenic event in human cancers. Our results suggest that the agents responsible for the high risk of bladder cancer in the black foot disease region may operate through an inflammation-based mechanism which increases the amount of DNA damage per mutagenic event.",
Arsenic,2298724,"Arsenic removal from aqueous solutions by adsorption onto iron oxide/activated carbon magnetic composite Abstract: In this work the adsorption features of activated carbon and the magnetic properties of iron oxides were combined in a composite to produce magnetic adsorbent. Batch experiments were conducted to study the adsorption behavior of arsenate onto the synthetic magnetic adsorbent. The effects of initial solution pH, contact time, adsorbent dosage and co-existing anionic component on the adsorption of arsenate were investigated. The results showed that the removal percentage of arsenate could be over 95% in the conditions of adsorbent dosage 5.0 g/L, initial solution pH 3.0-8.0, and contact time 1 h. Under the experimental conditions, phosphate and silicate caused greater decrease in arsenate removal percentage among the anions, and sulfate had almost no effect on the adsorption of arsenate. Kinetics study showed that the overall adsorption rate of arsenate was illustrated by the pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the arsenate adsorption data was tested. Both the models adequately describe the experimental data. Moreover, the magnetic composite adsorbent could be easily recovered from the medium by an external magnetic field. It can therefore be potentially applied for the treatment of water contaminated by arsenate.",
Arsenic,627808,"Glutathione plays different roles in the induction of the cytotoxic effects of inorganic and organic arsenic compounds in cultured BALB/c 3T3 cells Abstract: The cytotoxicity of arsenic compounds towards BALB/c 3T3 cells in culture was investigated, together with the role of glutathione (GSH) in the induction of the cytotoxic effects. The rank order of cytotoxicity was as follows: arsenite (As3+) > arsenate (As5+) > dimethylarsinic acid (DMAA) > methylarsonic acid (MAA) > trimethylarsine oxide (TMAO). Arsenobetaine, arsenocholine and the tetramethylarsonium ion were less toxic. Depletion of GSH enhanced the cytotoxic effects of As3+, As5+, MAA and TMAO, while the cytotoxicity of DMAA was markedly reduced by depletion of GSH. These results suggest that GSH plays a role in protecting the cells against the toxic effects of As3+, As5+, MAA and TMAO while it is involved in the induction of the cytotoxic effects of DMAA.",
Arsenic,53214,"General subcellular effects of lead, mercury, cadmium, and arsenic Abstract: This working paper summarizes the known ultrastructural and biochemical effects of lead, mercury, cadmium, and arsenic on subcellular organelle systems following in vivo administration. Documented metal-induced alterations in nuclear, mitochondrial, microsomal, and lysosomal functions are discussed in relation to their potential impact on cellular responses to other environmental agents. Each of the above elements has been found to interfere with normal cellular replication and genetic processes. Mitochondrial swelling and depression of respiratory function are discussed in relation to known metal-specific perturbations of mitochondrial heme biosynthetic pathway enzymes. Inhibition of microsomal enzyme activities and protein synthesis by lead and mercury is compared to the apparent absence of such effects following arsenic or cadmium exposure. Lysosomal uptake of all the metals is documented, but biochemical alterations in these structures have been reported for only mercury and cadmium. It is concluded that these toxic metals are capable of interacting with, and biochemically altering major cellular systems at dose levels below those required to produce signs of overt metal toxicity. The impact of these effects on cellular response to other metals and xenobiotics in complex exposure situations is presently unknown, and further research is urgently needed in this area.",
Arsenic,1350923,Mutations in C57Bl/6J and metallothionein knock-out mice induced by chronic exposure of sodium arsenate in drinking water Abstract: ,
Arsenic,1023516,"Well characteristics influencing arsenic concentrations in ground water Abstract: Naturally occurring arsenic contamination is common in ground water in the upper Midwest. Arsenic is most likely to be present in glacial drift and shallow bedrock wells that lie within the footprint of northwest provenance Late Wisconsinan glacial drift. Elevated arsenic is more common in domestic wells and in monitoring wells than it is in public water system wells. Arsenic contamination is also more prevalent in domestic wells with short screens set in proximity to an upper confining unit, such as glacial till. Public water system wells have distinctly different well-construction practices and well characteristics when compared to domestic and monitoring wells. Construction practices such as exploiting a thick, coarse aquifer and installing a long well screen yield good water quantity for public water system wells. Coincidentally, these construction practices also often yield low arsenic water. Coarse aquifer materials have less surface area for adsorbing arsenic, and thus less arsenic available for potential mobilization. Wells with long screens set at a distance from an upper confining unit are at lower risk of exposure to geochemical conditions conducive to arsenic mobilization via reductive mechanisms such as reductive dissolution of metal hydroxides and reductive desorption of arsenic.",
Arsenic,1021830,"Association between urinary arsenic and diabetes mellitus in the Korean general population according to KNHANES 2008 Abstract: <strong>INTRODUCTION: </strong>We present data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008 on the associations between urinary arsenic and diabetes mellitus in a representative sample of the adult Korean population.<br /><br /><strong>METHODS: </strong>This study was based on data obtained in KNHANES 2008, which was conducted for three years (2007-2009) using a rolling sampling design involving a complex, stratified, multistage, probability-cluster survey of a representative sample of the noninstitutionalized civilian population of South Korea.<br /><br /><strong>RESULTS: </strong>Geometric means of total urinary arsenic concentration in females and total participants with diabetes mellitus were significantly higher than in participants without diabetes mellitus after adjustment for covariates, including age, seafood consumption, body mass index (BMI), hypertension, area of residence, regional area, education level, and smoking and drinking status. Multiple regression analysis after similar adjustment showed that total urinary arsenic concentration was associated with diabetes status in the females and total participants. In addition, after similar adjustment, the odds ratios (ORs) for diabetes mellitus in female participants and all participants were 1.502 (95% CI, 1.038-2.171) and 1.312 (95% CI, 1.040-1.655), respectively, for doubling of the level of urinary total arsenic concentration.<br /><br /><strong>CONCLUSION: </strong>This study showed an association between total urinary arsenic concentration and the prevalence of diabetes mellitus in a representative sample of the adult population, especially women, with environmental arsenic exposure after adjustment for seafood intake and relevant diabetes risk factors.",
Arsenic,710880,"Cellular uptake, subcellular distribution and toxicity of arsenic compounds in methylating and non-methylating cells? Abstract: Arsenic is a known human carcinogen, inducing tumors of the skin, urinary bladder, liver and lung. Inorganic arsenic, existing in highly toxic trivalent and significantly less toxic pentavalent forms, is methylated to mono- and di-methylated species mainly in the liver. Due to the low toxicity of pentavalent methylated species, methylation has been regarded as a detoxification process for many years; however, recent findings of a high toxicity of trivalent methylated species have indicated the contrary. In order to elucidate the role of speciation and methylation for the toxicity and carcinogenicity of arsenic, systematic studies were conducted comparing cellular uptake, subcellular distribution as well as toxic and genotoxic effects of organic and inorganic pentavalent and trivalent arsenic species in both non-methylating (urothelial cells and fibroblasts) and methylating cells (hepatocytes). The membrane permeability was found to be dependent upon both the arsenic species and the cell type. Uptake rates of trivalent methylated species were highest and exceeded those of their pentavalent counterparts by several orders of magnitude. Non-methylating cells (urothelial cells and fibroblasts) seem to accumulate higher amounts of arsenic within the cell than the methylating hepatocytes. Cellular uptake and extrusion seem to be faster in hepatocytes than in urothelial cells. The correlation of uptake with toxicity indicates a significant role of membrane permeability towards toxicity. Furthermore, cytotoxic effects are more distinct in hepatocytes. Differential centrifugation studies revealed that elevated concentrations of arsenic are present in the ribosomal fraction of urothelial cells and in nucleic and mitochondrial fractions of hepatic cells. Further studies are needed to define the implications of the observed enrichment of arsenic in specific cellular organelles for its carcinogenic activity. This review summarizes our recent research on cellular uptake, distribution and toxicity of arsenic compounds in methylating and non-methylating cells.",
Arsenic,2343557,"Monitoring and Modeling the Effects of Groundwater Flow on Arsenic Transport in Datong Basin Abstract: Although arsenic-contaminated groundwater in the Datong Basin has been studied for more than 10 years, little has been known about the complex patterns of solute transport in the aquifer systems. Field monitoring and transient 3D unsaturated groundwater flow modeling studies were carried out on the riparian zone of the Sanggan River at the Datong Basin, northern China, to better understand the effects of groundwater flow on As mobilization and transport. The results indicate that irrigation is the primary factor in determining the groundwater flow paths. Irrigation can not only increase groundwater level and reduce horizontal groundwater velocity and thereby accelerate vertical and horizontal groundwater exchange among sand, silt and clay formations, but also change the HS- concentration, redox conditions of the shallow groundwater. Results of net groundwater flux estimation suggest that vertical infiltration is likely the primary control of As transport in the vadose zone, while horizontal water exchange is dominant in controlling As migration within the sand aquifers. Recharge water, including irrigation return water and flushed saltwater, travels downward from the ground surface to the aquifer and then nearly horizontally across the sand aquifer. The maximum value of As enriched in the riparian zone is roughly estimated to be 1 706.2 mg.d(-1) for a horizontal water exchange of 8.98 m(3).d(-1) close to the river and an As concentration of 190 mu g.L-1.",
Arsenic,1029043,"BRCA2-dependent homologous recombination is required for repair of Arsenite-induced replication lesions in mammalian cells Abstract: Arsenic exposure constitutes one of the most widespread environmental carcinogens, and is associated with increased risk of many different types of cancers. Here we report that arsenite (As[III]) can induce both replication-dependent DNA double-strand breaks (DSB) and homologous recombination (HR) at doses as low as 5 microM (0.65 mg/l), which are within the typical doses often found in drinking water in contaminated areas. We show that the production of DSBs is dependent on active replication and is likely to be the result of conversion of a DNA single-strand break (SSB) into a toxic DSB when encountered by a replication fork. We demonstrate that HR is required for the repair of these breaks and show that a functional HR pathway protects against As[III]-induced cytotoxicity. In addition, BRCA2-deficient cells are sensitive to As[III] and we suggest that As[III] could be exploited as a therapy for HR-deficient tumours such as BRCA1 and BRCA2 mutated breast and ovarian cancers.",
Arsenic,734899,"Nucleophosmin in the pathogenesis of arsenic-related bladder carcinogenesis revealed by quantitative proteomics Abstract: To investigate the molecular mechanisms of arsenic (As)-associated carcinogenesis, we performed proteomic analysis on E7 immortalized human uroepithelial cells after treatment with As in vitro. Quantitative proteomics was performed using stable isotope dimethyl labeling coupled with two-dimensional liquid chromatography peptide separation and mass spectrometry (MS)/MS analysis. Among 285 proteins, a total of 26 proteins were upregulated (ratio&gt;2.0) and 18 proteins were downregulated (ratio&lt;0.65) by As treatment, which are related to nucleotide binding, lipid metabolism, protein folding, protein biosynthesis, transcription, DNA repair, cell cycle control, and signal transduction. This study reports the potential significance of nucleophosmin (NPM) in the As-related bladder carcinogenesis. NPM was universally expressed in all of uroepithelial cell lines examined, implying that NPM may play a role in human bladder carcinogenesis. Upregulation of NPM tends to be dose- and time-dependent after As treatment. Expression of NPM was associated with cell proliferation, migration and anti-apoptosis. On the contrary, soy isoflavones inhibited the expression of NPM in vitro. The results suggest that NPM may play a role in the As-related bladder carcinogenesis, and soybean-based foods may have potential in the suppression of As/NPM-related tumorigenesis.",
Arsenic,1797840,"Fluorescence sensing of arsenate at nanomolar level in a greener way: naphthalene based probe for living cell imaging Abstract: Naphthalene-salisaldehyde conjugate (NAPSAL) is established as a novel arsenate (H2AsO4(-)) selective 'turn-on' fluorescence probe. It can detect as low as 5 × 10(-9) M H2AsO4(-) in HEPES buffered EtOH?:?water (0.1 M, 1?:?9, v/v, pH 7.4). Trace level H2AsO4(-) in drinking water samples is measured using standard addition method. Intracellular arsenate in Candida albicans, grown in arsenic contaminated water of Purbasthali has successfully been detected under fluorescence microscope.",
Arsenic,2278548,"Metronidazole and hydroxymetronidazole central nervous system distribution: 1. Microdialysis assessment of brain extracellular fluid concentrations in patients with acute brain injury Abstract: The distribution of metronidazole in the central nervous system has only been described based on cerebrospinal fluid data. However, extracellular fluid (ECF) concentrations may better predict its antimicrobial effect and/or side effects. We sought to explore by microdialysis brain ECF metronidazole distribution in patients with acute brain injury. Four brain-injured patients monitored by cerebral microdialysis received 500 mg of metronidazole over 0.5 h every 8 h. Brain dialysates and blood samples were collected at steady state over 8 h. Probe recoveries were evaluated by in vivo retrodialysis in each patient for metronidazole. Metronidazole and OH-metronidazole were assayed by high-pressure liquid chromatography, and a noncompartmental pharmacokinetic analysis was performed. Probe recovery was equal to 78.8% ± 1.3% for metronidazole in patients. Unbound brain metronidazole concentration-time curves were delayed compared to unbound plasma concentration-time curves but with a mean metronidazole unbound brain/plasma AUC0-? ratio equal to 102% ± 19% (ranging from 87 to 124%). The unbound plasma concentration-time profiles for OH-metronidazole were flat, with mean average steady-state concentrations equal to 4.0 ± 0.7 ?g ml(-1). This microdialysis study describes the steady-state brain distribution of metronidazole in patients and confirms its extensive distribution.",
Arsenic,1028879,"Severe pododermatitis in broiler breeder hens housed on pressure-treated slats Abstract: Severe foot-pad dermatitis was diagnosed in a case of broiler hens housed on slats made of lumber pressure-treated with chromated copper arsenate. Studies were conducted in an attempt to determine whether contact with the lumber caused the lesions. Breeder pullets were housed for 17 weeks on slats made from either untreated oak or pressure-treated lumber. Cresylic acid disinfectant was applied to one set of each slat type. Foot-pad lesions were scored and tissue arsenic levels were measured. Foot pads of the hens on pressure-treated slats were the only tissue with detectable arsenic levels. All groups developed foot-pad lesions, although the lesions appeared to be most severe, and to have developed earlier, in birds on pressure-treated disinfected slats.",
Arsenic,1351059,"Characterising the reactivity of metallic iron in Fe-0/As-rock/H2O systems by long-term column experiments Abstract: The intrinsic reactivity of 4 metallic iron materials (Fe-0) was investigated in batch and column experiments. The Fe0 reactivity was characterised by the extent of aqueous fixation of in-situ leached arsenic (As). Air-homogenised batch experiments were conducted for 1 month with 10.0 g/l of an As-bearing rock (ore material) and 0.0 or 5.0 g/l of Fe-0. Column experiments were performed for 2 and 3 months. Each dynamic experiment was made up of 2 glass columns in series. The first column contained 2.5 or 5.0 g of the ore material and the second column 0.0 or 5.0 g of a Fe-0 material. Results showed no significant reactivity difference in batch studies for all 4 materials; ZVI2 was by far the most reactive material in column experiments. This observation was attributed to the relative kinetics of production of aqueous As and Fe species under the experimental conditions and their impact on the formation of a protective film on Fe-0. Accordingly, no protective film could be built at the surface of the least reactive materials. The results corroborated the urgent need for unified experimental procedures to characterise Fe-0 materials.",
Arsenic,1677654,"External inorganic N source enhances the uptake of As species in garland chrysanthemum (C. coronarium) amended with chicken manure bearing roxarsone and its metabolites Abstract: Roxarsone (ROX), a widely used feed organoarsenic additive, is excreted as itself and its metabolites in animal manure. Animal manure is commonly applied with N fertilizer to meet the N demand of crop. We investigated the accumulation of As species in garland chrysanthemum plants fertilized with chicken manure (CM) bearing ROX and its metabolites, combined with different inorganic N sources (NH4(+), NO3(-) and urea), respectively. The change of pH, N forms and As species in soils was examined as well. The results show that As(V), As(III) and dimethylarsinic acid (DMA) were detectable in soils, and conversions between As species were affected by three inorganic N sources, irrespective of N form and soil pH. As(III) was the sole As species in garland chrysanthemum shoots, and As(III) and As(V) could be detected in roots. Urea, superior to NH4(+), significantly enhanced the uptake of As species in plants by promoting plant growth, while NO3(-) slightly reduced the As accumulation due to decreased biomass. As(III) was the dominant As compound (86.9-89.7%) in plants. Therefore, inorganic N fertilizers may inadvertently increase the risk of As contamination in plant from ROX via the way ROX?chicken?CM?soil?crop.",
Arsenic,2279290,"Regional specific groundwater arsenic levels and neuropsychological functioning: A cross-sectional study Abstract: Background: The purpose of the study was to examine the link between geographic information system (GIS)-estimated regional specific groundwater levels and neuropsychological functioning in a sample of individuals with and without cognitive impairment. Methods: This cross-sectional study design analyzed data from 1390 participants (733 Alzheimer's disease, 127 Mild Cognitive Impairment, and 530 with normal cognition) enrolled in the Texas Alzheimer's Research and Care Consortium. GISs analyses were used to estimate regional specific groundwater arsenic concentrations using the Environmental Systems Research Institute and arsenic concentrations from the Texas Water Development Board. Results: In the full cohort, regional specific arsenic concentrations were positively associated with language abilities (p?=?0.008), but associated with poorer verbal memory, immediate (p?=?0.008), and delayed (p?<?0.001), as well as poorer visual memory, immediate (p?=?0.02), and delayed (p?<?0.001). The findings varied by diagnostic category with arsenic being related with cognition most prominently among mild cognitive impairment cases. Conclusions: Overall, estimated regional specific groundwater arsenic levels were negatively associated with neuropsychological performance.",
Arsenic,2345635,"Crystallization and preliminary X-ray crystallographic studies of the ArsI C-As lyase from Thermomonospora curvata Abstract: Arsenic is a ubiquitous and carcinogenic environmental element that enters the biosphere primarily from geochemical sources, but also through anthropogenic activities. Microorganisms play an important role in the arsenic biogeochemical cycle by biotransformation of inorganic arsenic into organic arsenicals and vice versa. ArsI is a microbial nonheme ferrous-dependent dioxygenase that transforms toxic methylarsonous acid to the less toxic inorganic arsenite by C-As bond cleavage. An ArsI ortholog from the thermophilic bacterium Thermomonospora curvata was expressed, purified and crystallized. The crystals diffracted to 1.46?Å resolution and belonged to space group P43212 or its enantiomer P41212, with unit-cell parameters a = b = 42.2, c = 118.5?Å.",
Arsenic,1597419,"A novel autotrophic bacterium isolated from an engineered wetland system links nitrate-coupled iron oxidation to the removal of As, Zn and S Abstract: A neutrophilic, autotrophic bacterium that couples iron oxidation to nitrate reduction (iron-oxidizing bacteria [IOB]) under anoxic conditions was isolated from a working bioremediation site in Trail, British Columbia. The site was designed and developed primarily to treat high concentrations of Zn and As that originate from capped industrial landfill sites. The system consisted of two upflow biochemical reactor cells (BCR) followed by three vegetated wetland polishing cells with sub-surface flow and a holding pond. During a 5-year period (2003–2007), the system treated more than 19,100 m3 of contaminated water, removing and sequestering more than 10,700 kg of As, Zn and sulfate at average input water concentrations of: As, 58.6 mg?l?1 (±39.9 mg?l?1); Zn, 51.9 mg?l?1 (±35.4 mg?l?1) and SO4 2?, 781.5 mg?l?1 (±287.8 mg?l?1). The bacterium was isolated in order to better understand the mechanisms underlying the consistent As removal that took place in the system. Analysis using Basic Local Alignment Search Tool (BLAST) database showed that the closest homologies are to Candidatus accumulibacterphosphatis (95 % homology), Dechloromonas aromatica (94 %), and Sideroxydans lithotrophicus ES-1 (92 %) Within the BCR cells, the IOB oxidized Fe2+ generated by iron-reducing bacteria (IRB); the source of the iron was most likely biosolids and coatings of iron oxide on locally available sand used in the matrix. We have provisionally designated the novel bacterium as TR1.",
Arsenic,1345943,"Synthesis of a fluorescently labeled compound for the detection of arsenic-induced apoptotic HL60 cells Abstract: Arsenic compounds have shown medical usefulness since they proved to be effective in causing complete remission of acute promyelocytic leukemia. In this work we obtained a fluorescently labeled arsenic compound that can be used with current fluorescence techniques for basic and applied research, focused on arsenic-induced apoptosis studies. This compound is an arsanilic acid bearing a covalently linked FITC that was chemically synthesized and characterized by fluorescence, UV-Vis, mass and FTIR spectrometry. In addition, we assessed its apoptotic activity as well as its fluorescent labeling properties in HL60 cell line as a leukemia cell model through flow cytometry. We obtained a compound with a 1:1 FITC:arsenic ratio and a 595 m/z, confirming its structure by FTIR. This compound proved to be useful at inducing apoptosis in the leukemia cell model and labeling this apoptotic cell population, in such a way that the highest FITC fluorescence correlated with the highest arsenic amount.",
Arsenic,65137,"A unique pattern of hepatocyte proliferation in F344 rats following long-term exposures to low levels of a chemical mixture of groundwater contaminants Abstract: Most exposures of humans to environmental agents involve mixtures of chemicals, rather than individual chemicals. Some chemicals can cause hepatocellular proliferation and act as neoplastic promoters. Little is known concerning hepatocellular proliferation caused by chemical mixtures such as those found in groundwater at hazardous waste sites. Therefore, a 6 month study was performed to investigate hepatocellular proliferation and histopathological changes in F344 rats after long-term, low-level exposure to a mixture of groundwater contaminants. The seven chemicals used are among the most frequently detected contaminants associated with hazardous waste sites; arsenic, benzene, chloroform, chromium, lead, phenol and trichloroethylene. Male F344 rats were exposed to this mixture, or submixtures of the organic or inorganic chemicals, via drinking water for 6 months. The study design included a time-course experiment (i.e. 3 and 10 days and 1, 3 and 6 months) and a dose-response experiment. Hepatocellular proliferation studies were performed by subcutaneously implanting osmotic mini-pumps to continuously deliver 5-bromo-2'-deoxyuridine for 7 days, which labeled nuclei of proliferating cells. In all groups, there were no differences in weight gain, body weight, liver weight ratios or liver-associated plasma enzymes. Light microscopic evaluation revealed no lesions related to the treatments in any animals. However, significant increases in hepatocellular labeling were observed at the 3 and 10 day and 1 month exposure time points after treatment with the full mixture, as well as the organic or inorganic submixtures. Proliferating hepatocytes expressed a unique labeling pattern surrounding large hepatic veins (0.5-2.0 mm), but not central veins. This did not appear to be a regenerative response due to cytotoxic mechanisms, as assessed by the absence of increased plasma enzyme activity and the absence of hepatocellular lesions.",
Arsenic,1349991,"Quantitative piezospectroscopy of the 1s and 2p state of arsenic impurity in germanium Abstract: The results are presented of a study of the behaviour under uniaxial compression of absorption lines due to transitions from the ground state manifold of states of arsenic impurities in germanium to excited p states. It is found that the shear deformation potential constant Ell of the excited p states and conduction band minima of germanium is 16·4±0·2 eV. The equivalent deformation potential constant of the ground state, here designated as E~, is determined to be essentially the same (one analysis giving E~ = 16·5 ± 0·4 e V), a result in contrast to that found for donors in silicon. The results are compared with those obtained by other workers who use a variety of techniques. Good agreement is found between the present results and a number of the others although several discrepancies remain.",
Arsenic,710920,"Evidence from Chile that arsenic in drinking water may increase mortality from pulmonary tuberculosis Abstract: Arsenic in drinking water causes increased mortality from several cancers, ischemic heart disease, bronchiectasis, and other diseases. This paper presents the first evidence relating arsenic exposure to pulmonary tuberculosis, by estimating mortality rate ratios for Region II of Chile compared with Region V for the years 1958-2000. The authors compared mortality rate ratios with time patterns of arsenic exposure, which increased abruptly in 1958 in Region II and then declined starting in 1971. Tuberculosis mortality rate ratios in men started increasing in 1968, 10 years after high arsenic exposure commenced. The peak male 5-year mortality rate ratio occurred during 1982-1986 (rate ratio = 2.1, 95% confidence interval: 1.7, 2.6; P &lt; 0.001) and subsequently declined. Mortality rates in women were also elevated but with fewer excess pulmonary tuberculosis deaths (359 among men and 95 among women). The clear rise and fall of tuberculosis mortality rate ratios in men following high arsenic exposure are consistent with a causal relation. The findings are biologically plausible in view of evidence that arsenic is an immunosuppressant and also a cause of chronic lung disease. Finding weaker associations in women is unsurprising, because this is true of most arsenic-caused health effects. Confirmatory evidence is needed from other arsenic-exposed populations.",
Arsenic,1339684,"Genome-wide transcriptional response of the archaeon Thermococcus gammatolerans to cadmium Abstract: Thermococcus gammatolerans, the most radioresistant archaeon known to date, is an anaerobic and hyperthermophilic sulfur-reducing organism living in deep-sea hydrothermal vents. Knowledge of mechanisms underlying archaeal metal tolerance in such metal-rich ecosystem is still poorly documented. We showed that T. gammatolerans exhibits high resistance to cadmium (Cd), cobalt (Co) and zinc (Zn), a weaker tolerance to nickel (Ni), copper (Cu) and arsenate (AsO(4)) and that cells exposed to 1 mM Cd exhibit a cellular Cd concentration of 67 µM. A time-dependent transcriptomic analysis using microarrays was performed at a non-toxic (100 µM) and a toxic (1 mM) Cd dose. The reliability of microarray data was strengthened by real time RT-PCR validations. Altogether, 114 Cd responsive genes were revealed and a substantial subset of genes is related to metal homeostasis, drug detoxification, re-oxidization of cofactors and ATP production. This first genome-wide expression profiling study of archaeal cells challenged with Cd showed that T. gammatolerans withstands induced stress through pathways observed in both prokaryotes and eukaryotes but also through new and original strategies. T. gammatolerans cells challenged with 1 mM Cd basically promote: 1) the induction of several transporter/permease encoding genes, probably to detoxify the cell; 2) the upregulation of Fe transporters encoding genes to likely compensate Cd damages in iron-containing proteins; 3) the induction of membrane-bound hydrogenase (Mbh) and membrane-bound hydrogenlyase (Mhy2) subunits encoding genes involved in recycling reduced cofactors and/or in proton translocation for energy production. By contrast to other organisms, redox homeostasis genes appear constitutively expressed and only a few genes encoding DNA repair proteins are regulated. We compared the expression of 27 Cd responsive genes in other stress conditions (Zn, Ni, heat shock, ?-rays), and showed that the Cd transcriptional pattern is comparable to other metal stress transcriptional responses (Cd, Zn, Ni) but not to a general stress response.",
Arsenic,2337279,"A cross-sectional study of well water arsenic and child IQ in Maine schoolchildren Abstract: <strong>BACKGROUND: </strong>In recent studies in Bangladesh and elsewhere, exposure to arsenic (As) via drinking water is negatively associated with performance-related aspects of child intelligence (e.g., Perceptual Reasoning, Working Memory) after adjustment for social factors. Because findings are not easily generalizable to the US, we examine this relation in a US population.<br /><br /><strong>METHODS: </strong>In 272 children in grades 3-5 from three Maine school districts, we examine associations between drinking water As (WAs) and intelligence (WISC-IV).<br /><br /><strong>RESULTS: </strong>On average, children had resided in their current home for 7.3 years (approximately 75% of their lives). In unadjusted analyses, household well WAs is associated with decreased scores on most WISC-IV Indices. With adjustment for maternal IQ and education, HOME environment, school district and number of siblings, WAs remains significantly negatively associated with Full Scale IQ and Perceptual Reasoning, Working Memory and Verbal Comprehension scores. Compared to those with WAs?&lt;?5 ?g/L, exposure to WAs???5 ?g/L was associated with reductions of approximately 5-6 points in both Full Scale IQ (p?&lt;?0.01) and most Index scores (Perceptual Reasoning, Working Memory, Verbal Comprehension, all p's?&lt;?0.05). Both maternal IQ and education were associated with lower levels of WAs, possibly reflecting behaviors (e.g., water filters, residential choice) limiting exposure. Both WAs and maternal measures were associated with school district.<br /><br /><strong>CONCLUSIONS: </strong>The magnitude of the association between WAs and child IQ raises the possibility that levels of WAs???5 ?g/L, levels that are not uncommon in the United States, pose a threat to child development.",
Arsenic,1519053,"The role of lipoic acid in the protection against of metallic pollutant effects in the shrimp Litopenaeus vannamei (Crustacea, Decapoda) Abstract: The effects of cadmium (Cd) and arsenic (As), dosed alone or in combination have been poorly investigated in crustaceans. Besides, it is not known if dietary supplementation of exogenous antioxidants, like lipoic acid (LA), might prevent or even reverse toxic effects of Cd and As. The objective of the present study was to evaluate the role of lipoic acid in modulating biochemical responses after Cd and As exposures in Litopenaeus vannamei. Muscle from shrimp exposed to Cd alone or Cd+As showed a decrease in glutathione (GSH) levels, while the pre-treatment with LA reversed this situation. In this tissue, the pre-treatment with LA also induced an increase in glutathione-S-transferase (GST) activity in all groups. In hepatopancreas it was observed a marked accumulation of Cd and As, a decrease in the reactive oxygen species (ROS) concentration in response to Cd exposure alone (-LA); concomitant in the same group it was observed an increment of metallothionein-like content. As exposure induced an increase in GSH levels but LA reversed this increase. Also, LA showed to increase the GST activity in all groups treated. Besides, in this organ LA showed to augment total antioxidant competence. Obtained results indicate that LA can be used as a chemo-protectant against oxidative insults in shrimp.",
Arsenic,2064276,"Relationship between arsenic content of food and water applied for food processing Abstract: As part of a survey conducted by the Central Agricultural Office of Hungary, 67 food samples including beverages were taken from 57 food industrial and catering companies, 75% of them being small and medium-sized enterprises (SMEs). Moreover, 40% of the SMEs were micro entities. Water used for food processing was simultaneously sampled. The arsenic (As) content of solid food stuff was determined by hydride generation atomic absorption spectrometry after dry ashing. Food stuff with high water content and water samples were analyzed by inductively coupled plasma mass spectrometry. The As concentration exceeded 10?g/L in 74% of the water samples taken from SMEs. The As concentrations of samples with high water content and water used were linearly correlated. Estimated As intake from combined exposure to drinking water and food of the population was on average 40% of the daily lower limit of WHO on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL0.5) for As. Five settlements had higher As intake than the BMDL0.5. Three of these settlements are situated in Csongrád county and the distance between them is less than 55km. The maximum As intake might be 3.8?g/kg body weight.",
Arsenic,2278044,"Equilibria, kinetics, and spectroscopic analyses on the uptake of aqueous arsenite by two-line ferrihydrite Abstract: Arsenite sorption from aqueous solutions was investigated using two-line ferrihydrite at room temperature, as a function of solution pH and arsenite loading. The isotherms, pH envelopes, and kinetics of arsenite sorption were characterized and its mechanism was elucidated via X-ray absorption spectroscopic studies. Arsenite sorption showed only slight pH dependence with a sorption maximum centered around pH 8.0. The Langmuir isotherm is most appropriate for arsenite sorption over the wide range of pH, indicating the homogenous and monolayer sorption of arsenite. The kinetic study demonstrated that arsenite sorption onto two-line ferrihydrite is considerably fast and the equilibrium is achieved within the reaction time of 3 h. X-ray absorption near-edge structure spectroscopy elucidated a slight change in oxidation state of arsenite for the initial concentration of 13.35 mM at pH 4. The extended X-ray absorption fine structure (EXAFS) spectroscopy results indicate that types of surface complexes of arsenite appeared to be very similar to those proposed by the previous studies in that the bidentate binuclear corner-sharing (2C) complex is predominant at all the surface loadings. However, our EXAFS results suggest that regardless ofpH, the mixed complexes of2C and bidentate mononuclear edge-sharing surface complex (2E) as well as the 2C complex are favoured at low and intermediate surface loadings, but only the 2C complex is dominant at high surface loading. Overall, the EXAFS results support the efficient removal of arsenite by the two-line ferrihydrite through the formation of highly stable inner-sphere surface complexes, such as 2C complex.",
Arsenic,1337317,"Arsenic and selenium mobilisation from organic matter treated mine spoil with and without inorganic fertilisation Abstract: Organic matter amendments are applied to contaminated soil to provide a better habitat for re-vegetation and remediation, and olive mill waste compost (OMWC) has been described as a promising material for this aim. We report here the results of an incubation experiment carried out in flooded conditions to study its influence in As and metal solubility in a trace elements contaminated soil. NPK fertilisation and especially organic amendment application resulted in increased As, Se and Cu concentrations in pore water. Independent of the amendment, dimethylarsenic acid (DMA) was the most abundant As species in solution. The application of OMWC increased pore water dissolved organic-carbon (DOC) concentrations, which may explain the observed mobilisation of As, Cu and Se; phosphate added in NPK could also be in part responsible of the mobilisation caused in As. Therefore, the application of soil amendments in mine soils may be particularly problematic in flooded systems.",
Arsenic,1030552,"Assessment of oxidative stress and histopathology in juvenile northern pike (Esox lucius) inhabiting lakes downstream of a uranium mill Abstract: Lakes receiving effluent from the Key Lake uranium mill in northern Saskatchewan contain elevated trace metals, some of which are associated with increased reactive oxygen species (ROS) in cells and tissues causing oxidative stress. The potential for oxidative stress was assessed in juvenile (age 1+) northern pike (Esox lucius) collected from two exposure (high and low) and one reference lake near the Key Lake operation. The concentrations of total, reduced and oxidized glutathione and the ratio of oxidized to reduced glutathione in liver and kidney did not differ significantly among pike collected from exposure and reference lakes, with the exception of low exposure pike kidney that had significantly greater oxidized glutathione and ratio of oxidized to reduced glutathione. The concentrations of by-products of lipid peroxidation (malondialdehyde and 4-hydroxyalkenal) were significantly greater in kidney of pike collected from the reference lake compared to both exposure lakes. The activity of the antioxidant enzyme glutathione peroxidase in liver was greater in pike collected from the high exposure lake compared to the reference lake. Histopathological evaluations revealed greater pathology in reference lake pike as indicated by a greater number of pyknotic and fragmented nuclei and dilated tubules as well as a thickening of Bowman's capsule in kidney, and as a thickening of the primary filament epithelial padding in gills. In liver, hepatocyte morphology, including transsectional area and degree of vacuolation, differed among lakes without any clear signs of pathology. Trace metal analyses of muscle showed that eight elements (arsenic, cobalt, copper, iron, molybdenum, selenium, thallium, and uranium) were significantly elevated in pike collected from both exposure lakes compared to reference. These results provide only limited evidence of oxidative stress in exposure pike tissues and no evidence of histopathology despite indications that trace metals, most notably arsenic and selenium, were bioaccumulating in tissue.",
Arsenic,1597434,"Biological phosphorus removal inhibition by roxarsone in batch culture systems Abstract: Roxarsone has been extensively used in the feed of animals, which is usually excreted unchanged in the manure and eventually enter into animal wastewater, challenging the biological phosphorus removal processes. Knowledge of its inhibition effect is key for guiding treatment of roxarsone-contaminated wastewater, and is unfortunately keeping unclear. We study the inhibition of roxarsone on biological phosphorus removal processes for roxarsone-contaminated wastewater treatment, in terms of the removal and rates of chemical oxygen demand (COD), phosphate. Results showed that presence of roxarsone considerably limited the COD removals, especially at roxarsone concentration exceeding 40mgL(-1). Additionally, roxarsone inhibited both phosphorus release and uptake processes, consistent with the phosphate profiles during the biological phosphorus removal processes; whereas, roxarsone is more toxic to phosphorus uptake process, than release function. The results indicated that it is roxarsone itself, rather than the inorganic arsenics, inhibit biological phosphorus removal processes within both aerobic and anaerobic roxarsone-contaminated wastewater treatment.",
Arsenic,2347776,A rule of thumb for testing symmetry about an unknown median against a long right tail Abstract: A rule of thumb for testing symmetry of an unknown univariate continuous distribution against the alternative of a long right tail is proposed. Our proposed test is based on the concept of exceedance statistic and is ad hoc in nature. Exact performances of the proposed rule are investigated in detail. Some results from an asymptotic point of view are also provided. We compare our proposed test with several classical tests which are practically applicable and are known to be exact or nearly distribution free. We see that the proposed rule is better than most of the existing tests for symmetry and can be applied with ease. An illustration with real data is provided.,
Arsenic,2347595,"Electrochemical arsine generators for arsenic determination Abstract: Arsine generation is the gateway for several sensitive and selective methods of As determination. An electrochemical arsine generator (EAG) is especially green: we report here the use of two electrode materials, aluminum and highly oriented (ordered) pyrolytic graphite (HOPG) never before used for this purpose. The first is operated on a novel constant voltage mode: current flows only when the sample, deliberately made highly conductive with acid, is injected. As a result, the cathode, despite being a highly active metal that will self-corrode in acid, lasts a long time. This EAG can be made to respond to As(III) and As(V) in an equivalent fashion and is fabricated with two readily available chromatographic T-fittings. It permits the use of a wire roll as the cathode, permitting rapid renewal of the electrode. The HOPG-based EAG is easily constructed from ion chromatography suppressor shells and can convert As(III) to AsH3 quantitatively but has significantly lower response to As(V); this difference can be exploited for speciation. The success of Al, an active metal, also dispels the maxim that metals with high hydrogen overpotential are best for electrochemical hydride generation. We report construction, operation, and performance details of these EAGs. Using gas phase chemiluminescence (GPCL) with ozone as a complementary green analytical technique, we demonstrate attractive limits of detection (LODs) (S/N = 3) of 1.9 and 1.0 ?g/L As(V) and As(III) for the HOPG-based EAG and 1.4 ?g/L As(V) or As(III) for the Al-based EAG, respectively. Precision at the ?20 ?g/L As(V) level was 2.4% and 2.1% relative standard deviation (RSD) for HOPG- and Al-based EAGs, respectively. Both HOPG- and Al-based EAGs permitted a sample throughput of 12/h. For groundwater samples from West Texas and West Bengal, India, very comparable results were obtained with parallel measurements by induction coupled plasma-mass spectrometry.",
Arsenic,1337262,"Characterization of arsenic resistant bacteria from arsenic rich groundwater of West Bengal, India Abstract: Sixty-four arsenic (As) resistant bacteria isolated from an arsenic rich groundwater sample of West Bengal were characterized to investigate their potential role in subsurface arsenic mobilization. Among the isolated strains predominance of genera Agrobacterium/Rhizobium, Ochrobactrum and Achromobacter which could grow chemolitrophically and utilize arsenic as electron donor were detected. Higher tolerance to As(3+) [maximum tolerable concentration (MTC): ?10 mM], As(5+) (MTC: ?100 mM) and other heavy metals like Cu(2+), Cr(2+), Ni(2+) etc. (MTC: ?10 mM), presence of arsenate reductase and siderophore was frequently observed among the isolates. Ability to produce arsenite oxidase and phosphatase enzyme was detected in 50 and 34 % of the isolates, respectively. Although no direct correlation among taxonomic identity of bacterial strains and their metabolic abilities as mentioned above was apparent, several isolates affiliated to genera Ochrobactrum, Achromobacter and unclassified Rhizobiaceae members were found to be highly resistant to As(3+) and As(5+) and positive for all the test properties. Arsenate reductase activity was found to be conferred by arsC gene, which in many strains was coupled with arsenite efflux gene arsB as well. Phylogenetic incongruence between the 16S rRNA and ars genes lineages indicated possible incidence of horizontal gene transfer for ars genes. Based on the results we propose that under the prevailing low nutrient condition inhabitant bacteria capable of using inorganic electron donors play a synergistic role wherein siderophores and phosphatase activities facilitate the release of sediment bound As(5+), which is subsequently reduced by arsenate reductase resulting into the mobilization of As(3+) in groundwater.",
Arsenic,2088556,"Adaptation through horizontal gene transfer in the cryptoendolithic red alga Galdieria phlegrea Abstract: Thriving in the hot, acidic, and metal-rich environments associated with geothermal areas is possible for only a few eukaryotes, with the Cyanidiophytina red algae (Cyanidium, Galdieria, and Cyanidioschyzon) being a famous example. These unicellular taxa can live in pH 0-4 and temperatures reaching up to 56°C [1,2]. Because Cyanidiophytina is sister to a vast array of mesophilic red algae (the Rhodophytina), such as the unicellular Porphyridium and the seaweed Chondrus[3], the genetic basis of their adaptation to extreme environments is of great interest from both the perspective of biotechnology and of evolution. The recently completed 13.7 Mbp genome sequence from the hot-spring dwelling Galdieria sulphuraria demonstrated that horizontal gene transfer (HGT) from prokaryotic sources provided this taxon with remarkable metabolic versatility (e.g., glycerol metabolism) and the ability to survive in its hostile environment (e.g., genes to detoxify mercury and arsenic) [4]. To explore the role of HGT in other members of this genus, we generated an 11.4 Mbp draft genome assembly from the sister taxon G. phlegrea DBV 009 [5]. In contrast to G. sulphuraria, this species is adapted to dry habitats near fumaroles such as fissures between rocks or cryptoendolithic environments [5,6]. Here, we provide evidence for extensive gene loss in the common ancestor of Cyanidiophytina that includes the eukaryote-derived loci required for urea utilization. Surprisingly, we find that G. phlegrea has regained the complete set of genes required for urea hydrolysis through HGT from eubacteria. The unlinked nature of these genes is likely explained by multiple gene transfers that resulted in assembly of the pathway in G. phlegrea. Our study demonstrates that genome reduction, a common outcome in eukaryotes for adaptation to a specialized niche, can be ameliorated by the gain of once lost, or novel functions through HGT.",
Arsenic,1147196,"Interactions of arsenic with human prostate progenitor cells Abstract: Inorganic arsenic is a carcinogenic metalloid commonly found in the environment. Human exposure to arsenic has been associated with various urogenital cancers, including tumors of the kidney, urinary bladder, ureter and prostate. Our recent work in CD1 mice shows transplacental arsenic exposure can induce tumors or proliferative lesions at multiple sites in the urogenital system (UGS), indicating that during fetal exposure stem/progenitor cells may be a key target cell population. The present work sought to investigate interactions of arsenic with progenitor cells of the UGS. By single cell cloning of the immortalized, normal human prostate-derived, non-tumorigenic RWPE-1 epithelial cell line, a prostate epithelial stem/progenitor cell type has been established [Differentiation, Tokar et al. (in press)]. These cells, termed WPE-stem, show characteristics of stem/progenitor cells that are found in both the cell populations of the UGS and in the prostate. Stem/progenitor markers in WPE-stem cells include high expression of p63 and cytokeratin (CK) 5/14, low CK 18 and androgen receptor expression, high MMP-2 activity, high colony forming efficiency, and steroid-independence for growth and survival. To test our hypothesis that arsenic may target stem cell populations during malignant transformation, initial studies compared the effects of sodium arsenite on WPE-stem cells to those of the parent line. WPE-stem cells were clearly more resistant to arsenic cytotoxicity with an LC50 (26.8 uM ? 1.6; 48 h), nearly double that of RWPE-1 (15.2 uM ? 1.8). High-level arsenic exposure (30 uM; 24 h) caused a 236% increase in apoptosis in RWPE-1 cells but only a 77% increase in WPE-stem. This apoptotic resistance in WPE-stem cells is consistent with the acquired arsenic resistance that occurs concurrently during malignant transformation by chronic arsenic exposure. Further studies of the effects of arsenic on this stem/progenitor cell line are ongoing and may help to define the mechanism of arsenic-induced carcinogenesis in the prostate and UGS.",
Arsenic,628536,"Diabetes mellitus associated with arsenic exposure in Bangladesh Abstract: The objective of this study was to assess whether arsenic exposure is a risk factor for diabetes mellitus as indicated in a few earlier studies. Arsenic in drinking water is known to occur in western Bangladesh, and in 1996, two of the authors conducted a survey of the prevalence of diabetes mellitus among 163 subjects with keratosis taken as exposed to arsenic and 854 unexposed individuals. Diabetes mellitus was determined by history of symptoms, previously diagnosed diabetes, glucosuria, and blood sugar level after glucose intake. The crude prevalence ratio for diabetes mellitus among keratotic subjects exposed to arsenic was 4.4 (95% confidence interval 2.5-7.7) and increased to 5.2 (95% confidence interval 2.5-10.5) after adjustment for age, sex, and body mass index. On the basis of a few earlier measurements of arsenic concentrations in drinking water by the authorities in Bangladesh and another 20 new ad hoc analyses, approximate time-weighted exposure levels to arsenic in drinking water could be estimated for each subject. Three time-weighted average exposure categories were created, i.e., less than 0.5, 0.5-1.0, and more than 1.0 mg/liter. For the unexposed subjects, the corresponding prevalence ratios were 1.0, 2.6, 3.9, and 8.8, representing a significant trend in risk (p < 0.001). The result corroborates earlier studies and suggests that arsenic exposure is a risk factor for diabetes mellitus.",
Arsenic,1349147,"Cyc07 enhances arsenite tolerance by reducing As levels in Nicotiana tabacum and Arabidopsis thaliana Abstract: Arsenic is a major pollutant that contaminates land, water, and air. We previously reported that the expression of tobacco Ntcyc07 confers arsenite (As III) tolerance by decreasing the arsenic level by promoting the transcription of the arsenite export carrier ACR3 and inhibiting that of the As(III) uptake transporter FPS1 in S. cerevisiae (Mok et al. 2008). To examine if Ntcyc07 is also involved in As(III) tolerance and accumulation in plants, we generated transgenic tobacco and Arabidopsis that overexpress Ntcyc07. The Ntcyc07 tobacco exhibited increased tolerance to but decreased accumulation of arsenite, but the Ntcyc07 Arabidopsis showed enhanced As(III) tolerance and no change in the As level. In contrast, Atcyc07 knockout Arabidopsis (Atcyc07 is a homolog of Ntcyc07) displayed reduced As(III) tolerance and an increased As level. Taken together, cyc07 promotes As(III) tolerance by decreasing the cellular accumulation of arsenite in plants.",
Arsenic,627639,"Arsenic exposure alters hepatic arsenic species composition and stress-mediated gene expression in the common killifish (Fundulus heteroclitus) Abstract: In the present paper, we examine how arsenic species accumulate in fish liver and explore the hypothesis that sublethal arsenic concentrations in fish hepatic tissue interfere with stress-mediated gene expression. We exposed killifish (Fundulus heteroclitus) to 787 or 0 microg/L arsenic in tank water for 2 weeks. Arsenic exposure elevated total liver arsenic from 3.4 microg/g wet weight (control fish) to 9.6 microg/g wet weight, and resulted in a higher relative proportion of toxic (e.g. monomethylarsenous acid, dimethylarsenous acid, arsenic V) versus benign (arsenobetaine) arsenic species in this tissue. Following the exposure period, arsenic-treated and control fish were then subjected to a stress protocol: confinement and mechanical chasing for 15 min every 3 h. Liver tissue and blood were sampled from fish not exposed to the stressor at time 0, and at 8, 12, 24 and 40 h following the first stressor. Concentrations of the stress hormone cortisol increased significantly, and glucocorticoid receptor mRNA levels increased and then decreased in both groups, but patterns were nearly identical between arsenic pre-treated and arsenic untreated fish. Prior arsenic exposure prevented the stress-induced increases in stress-responsive LDH-B mRNA levels and enzyme activity observed in fish that had not been exposed to arsenic. However, in another stress-responsive gene, PEPCK, arsenic did not interfere with the stress-induced increase in gene expression, suggesting that the effects of arsenic on stress-mediated gene expression are complex and may involve regulatory pathways that differ between these two genes.",
Arsenic,1249016,"Total arsenic and selenium analysis in Marcellus shale, high-salinity water, and hydrofracture flowback wastewater Abstract: Trace levels of arsenic and selenium can be toxic to living organisms yet their quantitation in high ionic strength or high salinity aqueous media is difficult due to the matrix interferences which can either suppress or enhance the analyte signal. A modified thiol cotton fiber (TCF) method employing lower flow rates and centrifugation has been used to remove the analyte from complex aqueous media and minimize the matrix interferences. This method has been tested using a USGS (SGR-1b) certified reference shale. It has been used to analyze Marcellus shale samples following microwave digestion as well as spiked samples of high salinity water (HSW) and flow back wastewater (WRF6) obtained from an actual gas well drilling operation. Quantitation of arsenic and selenium is carried out by graphite furnace atomic spectroscopy (GFAAS). Extraction of arsenic and selenium from Marcellus shale exposed to HSW and WRF6 for varying lengths of time is also reported.",
Arsenic,1016379,"Cytoprotective effects of silymarin on epithelial cells against arsenic-induced apoptosis in contrast with quercetin cytotoxicity Abstract: <strong>AIMS: </strong>To establish the differential cytoprotective activity against arsenic (As) toxicity of the flavonoids silymarin (S), which is without protective effects on cancer cells, and quercetin (Q). Arsenic (As) has a paradoxical biomedical role: it causes oxidative damage to normal cells leading to death or malignant transformation, but can be used, for the same reason, as an anticancer pro-apoptotic agent at high doses.<br /><br /><strong>MAIN METHODS: </strong>Aqueous hydroperoxides (AHP), JNK (c-Jun N-terminal kinase) activation, caspase activity and death phenotype were assessed in CHO-K1 cells treated with As, S, Q, As+S and As+Q (p&lt;0.05).<br /><br /><strong>KEY FINDINGS: </strong>Q proved to be toxic and did not exert complete protection against As, and only S was able to protect cells from As-induced oxidative death, which started after 4h with caspase activation and phosphatidylserine exteriorization on the outer cellular membrane. Although both flavonoids counteracted As-induced JNK activation (an early stress response, i.e. exposure biomarker), AHP were increased by As and Q (p&lt;0.05). Moreover, Q-treated cells triggered per se apoptosis and even necrosis. Also, the classical sequence oxidative stress-JNK activation-cell death was seen for As, but not for Q, with S stopping the sequence.<br /><br /><strong>SIGNIFICANCE: </strong>These results strongly suggest that the use of silymarin increases the possibility of designing better arsenic-based cancer chemotherapies with less toxicity to normal cells.",
Arsenic,1340051,"Hydrogeochemical contrast between brown and grey sand aquifers in shallow depth of Bengal Basin: Consequences for sustainable drinking water supply Abstract: Delineation of safe aquifer(s) that can be targeted by cheap drilling technology for tubewell (TW) installation becomes highly imperative to ensure access to safe and sustainable drinking water sources for the arsenic (As) affected population in Bengal Basin. This study investigates the potentiality of brown sand aquifers (BSA) as a safe drinking water source by characterizing its hydrogeochemical contrast to grey sand aquifers (GSA) within shallow depth (&lt;70 m) over an area of 100 km(2) in Chakdaha Block of Nadia district, West Bengal, India. The results indicate that despite close similarity in major ion composition, the redox condition is markedly different in groundwater of the two studied aquifers. The redox condition in the BSA is delineated to be Mn oxy-hydroxide reducing, not sufficiently lowered for As mobilization into groundwater. In contrast, the enrichments of NH(4)(+), PO(4)(3-), Fe and As along with lower Eh in groundwater of GSA reflect reductive dissolution of Fe oxy-hydroxide coupled to microbially mediated oxidation of organic matter as the prevailing redox process causing As mobilization into groundwater of this aquifer type. In some portions of GSA the redox status even has reached to the stage of SO(4)(2-) reduction, which to some extent might sequester dissolved As from groundwater by co-precipitation with authigenic pyrite. Despite having low concentration of As in groundwater of the BSA the concentration of Mn often exceeds the drinking water guidelines, which warrants rigorous assessment of attendant health risk for Mn prior to considering mass scale exploitation of the BSA for possible sustainable drinking water supply.",
Arsenic,1797822,"Determination of Arsenic Species in Rice from Thailand and Other Asian Countries Using Simple Extraction and HPLC-ICP-MS Analysis Abstract: Human exposure to arsenic (As) via rice consumption is of increasing concern. In the present study, the extraction and HPLC-ICP-MS analysis for As speciation in rice were investigated. A simple extraction with water and digestion with ?-amylase followed by the analysis using ion-paring mode HPLC separation was developed. The method showed good extraction efficiencies (generally &gt;80%) and column efficiencies (&gt;90%) for rice samples. The optimization of mobile phase showed well separated peaks of As species. The limits of quantification (LOQ) of As(III), As(V), MMA, and DMA that were calculated based on sample mass were 1.6, 2.0, 2.0, and 1.6 ?g kg(-1), respectively. A total of 185 rice samples (various types of rice) collected from different four regions in Thailand and some other Asian countries were analyzed. The total As and inorganic As in rice samples were in the ranges of 22.51-375.39 and 13.89-232.62 ?g kg(-1), respectively. The estimated weekly intake of inorganic As from rice by Thai people accounted for 13.91-29.22% of the provisional tolerable weekly intake (PTWI).",
Arsenic,1018333,"Hair analysis does not support hypothesized arsenic and chromium exposure from drinking water in Woburn, Massachusetts Abstract: We hypothesized that residents of Woburn, Massachusetts, had been exposed to as much as 70 microg/l of arsenic (As) and 240 microg/l of chromium (Cr) in drinking water from municipal supply wells G and H. To test this hypothesis, we measured the concentrations of As and Cr in 82 hair samples donated by 56 Woburn residents. Thirty-six samples were cut between 1964 and 1979, the period during which wells G and H were in operation. The remainder were cut either before 1964 (1938-1963; n = 26) or after 1979 (1982-1994; n = 20). Washed hair samples were analyzed by instrumental neutron activation. Exposure to the well water--measured as access--was estimated using well pumping records and a model of the Woburn water distribution system. Our results show that access to wells G and H water was not significantly correlated (95% confidence interval) with As and Cr concentrations measured in the hair of Woburn residents, but As concentrations have declined significantly over the last half century. Linear regression of As concentrations (micrograms per gram) upon year of hair cut and access to wells G and H water yielded a standard coefficient for year of -0. 0074 +/- 0.0017 (standard error; p = 2.5 -multiple- 10(-5)) and -0.12 +/- 0.10 (p = 0.22) for access. The r2 value for the model was 0.19. The geometric mean concentrations (geometric standard deviation) of As and Cr in the hair of residents who had access (i.e., relative access estimate &gt;0) to wells G and H water (n = 27) were 0.14 (2.6) and 2.29 (1.8) microg/g, respectively; the geometric mean concentrations of As and Cr in all of the hair samples from residents who did not have access (1938-1994; n = 55) were 0.13 (3.0) and 2.19 (2.0) microg/g, respectively.",
Arsenic,628380,"Arsenic carcinogenesis in the skin Abstract: Chronic arsenic poisoning is a world public health issue. Long-term exposure to inorganic arsenic (As) from drinking water has been documented to induce cancers in lung, urinary bladder, kidney, liver and skin in a dose–response relationship. Oxidative stress, chromosomal abnormality and altered growth factors are possible modes of action in arsenic carcinogenesis. Arsenic tends to accumulate in the skin. Skin hyperpigmentation and hyperkeratosis have long been known to be the hallmark signs of chronic As exposure. There are significant associations between these dermatological lesions and risk of skin cancer. The most common arsenic-induced skin cancers are Bowen’s disease (carcinoma in situ), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Arsenic-induced Bowen’s disease (As-BD) is able to transform into invasive BCC and SCC. Individuals with As-BD are considered for more aggressive cancer screening in the lung and urinary bladder. As-BD provides an excellent model for studying the early stages of chemical carcinogenesis in human beings. Arsenic exposure is associated with G2/M cell cycle arrest and DNA aneuploidy in both cultured keratinocytes and As-BD lesions. These cellular abnormalities relate to the p53 dysfunction induced by arsenic. The characteristic clinical figures of arsenic-induced skin cancer are: (i) occurrence on sun-protected areas of the body; (ii) multiple and recrudescent lesions. Both As and UVB are able to induce skin cancer. Arsenic treatment enhances the cytotoxicity, mutagenicity and clastogenicity of UV in mammalian cells. Both As and UVB induce apoptosis in keratinocytes by caspase-9 and caspase-8 signaling, respectively. Combined UVB and As treatments resulted in the antiproliferative and proapoptotic effects by stimulating both caspase pathways in the keratinocytes. UVB irradiation inhibited mutant p53 and ki-67 expression, as well as increased in the number of apoptotic cells in As-BD lesions which resulted in an inhibitory effect on proliferation. As-UVB interaction provides a reasonable explanation for the rare occurrences of arsenical cancer in the sun-exposed skin. The multiple and recurrent skin lesions are associated with cellular immune dysfunction in chronic arsenism. A decrease in peripheral CD4+ cells was noticed in the inhabitants of arsenic exposure areas. There was a decrease in the number of Langerhans cells in As-BD lesion which results in an impaired immune function on the lesional sites. Since CD4+ cells are the target cell affected by As, the interaction between CD4+ cells and epidermal keratinocytes under As affection might be closely linked to the pathogenesis of multiple occurrence of arsenic-induced skin cancer. In this review, we provide and discuss the pathomechanisms of arsenic skin cancer and the relationship to its characteristic figures. Such information is critical for understanding the molecular mechanism for arsenic carcinogenesis in other internal organs.",
Arsenic,1021695,"Effect of deep tube well use on childhood diarrhoea in Bangladesh Abstract: <strong>OBJECTIVE: </strong>To determine whether the installation of deep tube wells to reduce exposure to groundwater arsenic in rural Bangladesh had an effect on the incidence of childhood diarrhoeal disease.<br /><br /><strong>METHODS: </strong>Episodes of diarrhoeal disease in children aged under 5 years that occurred on one specified day each month between 2005 and 2006 were reported to community health workers for six rural villages. A geographical information system containing details of household water use and sanitation in the villages was built using data obtained by a global positioning system survey. The information system also included health, spatial and demographic data. A field survey was carried out to determine whether households obtained drinking water from deep tube wells installed in 2005. The effect of deep tube well use on the incidence of childhood diarrhoea was assessed using a random effects negative binomial regression model.<br /><br /><strong>FINDINGS: </strong>The risk of childhood diarrhoea was 46% lower in the 179 households that used a deep tube well than in the 364 that used a shallow tube well (P=0.032). Neither socioeconomic status, latrine density, population density nor study year had a significant influence on disease risk. The incidence of childhood diarrhoea declined dramatically between 2005 and 2006, irrespective of water source.<br /><br /><strong>CONCLUSION: </strong>The introduction of deep tube wells to reduce arsenic in drinking water in rural Bangladesh had the additional benefit of lowering the incidence of diarrhoea among young children.",
Arsenic,1019454,"Determination of arsenic in urine by atomic absorption spectrophotometry for biological monitoring of occupational exposure to arsenic Abstract: An atomic absorption spectrophotometric (AAS) method was successfully applied to analysis of urine for arsenic (As) as a measure of biological monitoring of occupational exposure to As in Vietnam. The application of the method to urine samples from 75 non-exposed control urbanites (after 2-day abstinence from sea foods) gave a reference level of 62.4 +/- 11.6 microg/l (as mean +/- S.D.), from which the upper limit of the normal value (74 microg/l as mean +/- 1 S.D.) and the acceptable limit (100 microg/l as mean +/- 3S.D.) were deduced. Further application to urine samples from 147 workers occupationally exposed to As in Bacthai Non-ferrous Metallurgic Corporation showed significantly elevated levels of As in urine, with mean +/- S.D. of 78.5 +/- 20.2 microg/l. Improvement of working conditions to reduce As exposure resulted in substantial reduction in the ratio of those with urinary As at the level in excess of the acceptable limit. The practical importance of total arsenic determination in urine after 2-day sea food abstinence is discussed in connection with current conditions in analytical laboratories in Vietnam.",
Arsenic,1358038,"The Sequential Determination of Arsenic, Selenium, Germanium and Tin as Their Hydrides by Gas-Solid Chromatography with an Atomic Absorption Detector Abstract: A method was described for the sequential determination of hydrides of arsenic (7440382), germanium (7440564), selenium (7782492), and tin (7440315) in a single run by atomic absorption spectrometry. The hydrides were generated and determined using gas chromatography with an atomic absorption detector. The plug of vaporized hydrides was split into two approximately equal portions. One of these was introduced directly into the flame and analyzed for selenium. The other passed through a chromatographic column which served to separate arsenic, germanium and tin hydrides. While the method resulted in a two fold decrease in sensitivity for each analyte, it avoided separation problems associated with the marked chromatographic overlap of selenium and tin hydrides. The periodic step variation in flow rate during the chromatographic separation provided sufficient time for the necessary manipulations and yet preserved peak shape and minimized the analysis time. Detection limits ranged from 3 parts per billion (ppb) for arsenic to 13ppb for germanium with linear dynamic ranges of about 1.5 orders of magnitude. Relative standard deviations evaluated in the middle of the working range varied from 2 to 11 percent. Manual lamp selection and monochromator adjustment were facilitated by the chromatographic parameters chosen. The time for analysis was 5 minutes.",
Arsenic,1797767,"Protective effects of Vernonia amygdalina against sodium arsenite-induced genotoxicity in rat Abstract: <strong>OBJECTIVES: </strong>Contamination of the environment with arsenic (As) from both human and natural sources is known as a global problem. This study investigated the chemoprotective potential of Vernonia amygdalina leave extract against sodium arsenite-induced genotoxicity and hepatotoxicity.<br /><br /><strong>MATERIALS AND METHODS: </strong>Genotoxic effects were evaluated in the rat bone marrow using micronuclei. The gamma glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP) activities were assayed in rat serum.<br /><br /><strong>RESULTS: </strong>Pre-treatment with extract of V. amygdalina at doses 5 mg/kg and 10 mg/kg significantly decreased the frequency of micronucleated polychromatic erythrocytes (PCEs). The GGT and ALP activities were elevated more than fourfold, in the liver of rats treated with sodium arsenite, while it was reduced almost to half when the sodium arsenit-treated rats were fed fresh V. amgdalina leave extracts The phytochemical constituents of V. amygdalina assayed in this study may be responsible for high radical scavenging of the DPPH free radical observed.<br /><br /><strong>CONCLUSION: </strong>The present results indicate that V. amygdalina extract is capable of suppressing the chromosomal aberration induced by sodium arsenite in rat. Thus, V. amygdalina may be a potent chemoprotective agent against the toxicity of sodium arsenite in rats.",
Arsenic,1031444,"Nanoencapsulation of quercetin enhances its dietary efficacy in combating arsenic-induced oxidative damage in liver and brain of rats Abstract: <strong>AIMS: </strong>This study was performed to evaluate the therapeutic efficacy of nanocapsulated flavonoidal quercetin (QC) in combating arsenic-induced reactive oxygen species (ROS)-mediated oxidative damage in hepatocytes and brain cells in a rat model.<br /><br /><strong>MAIN METHODS: </strong>Hepatic and neuronal cell damage in rats was made by a single injection (sc) of sodium arsenite (NaAsO(2), 13 mg/kg b. wt. in 0.5 ml of physiological saline). A single dose of 500 microl of quercetin suspension (QC) (QC 8.98 micromol/kg) or 500 microl of nanocapsulated QC (NPQC) (QC 8.98 micromol/kg) was given orally to rats at 90 min prior to the arsenite injection.<br /><br /><strong>KEY FINDINGS: </strong>Inorganic arsenic depositions (182+/-15.6 and 110+/-12.8 ng/g protein) were found in hepatic and neuronal mitochondrial membranes. Antioxidant levels in hepatic and neuronal cells were reduced significantly by arsenic. NPQC prevented the arsenite-induced reduction in antioxidant levels in the liver and brain. Arsenic induced a substantial decrease in liver and brain cell membrane microviscosities, and NPQC treatment resulted in a unique protection against the loss. A significant correlation between mitochondrial arsenic and its conjugated diene level was observed both in liver and brain cells for all experimental rats.<br /><br /><strong>SIGNIFICANCE: </strong>Arsenic-specific antidotes are used against arsenic-induced toxicity. However, the target site is poorly recognized and therefore achieving an active concentration of drug molecules can be a challenge. Thus, our objective was to formulate NPQC and to investigate its therapeutic potential in an oral route against arsenite-induced hepatic and neuronal cell damage in a rat model.",
Arsenic,627403,"Mutagenicity of arsenic in mammalian cells: Role of reactive oxygen species Abstract: Arsenite, the trivalent form of arsenic present in the environment, is a known human carcinogen that lacked mutagenic activity in bacterial and standard mammalian cell mutation assays. We show herein that when evaluated in an assay (AL cell assay), in which both intragenic and multilocus mutations are detectable, that arsenite is in fact a strong dose-dependent mutagen and that it induces mostly large deletion mutations. Cotreatment of cells with the oxygen radical scavenger dimethyl sulfoxide significantly reduces the mutagenicity of arsenite. Thus, the carcinogenicity of arsenite can be explained at least in part by it being a mutagen that depends on reactive oxygen species for its activity.",
Arsenic,744843,"Lack of dna single strand breaks in a lung epithelial cell line after exposure to arsenic Abstract: Arsenic (As) is a carcinogen whose most important target organs include the skin and lungs. Exposure can occur via water ingestion, or inhalation, as As is a by-product of fossil fuel combustion and other industrial activities. The carcinogenic mechanism of action for As remains unclear. One hypothesis proposes As induces cancer by creating oxidative stress. In previous studies we found modest evidence of increased peroxidation after exposure of cells to inorganic As as arsenite (iAs). To study the possible mechanistic link between As exposure and lung carcinogenesis, we examined iAs induction of DNA single strand breaks (SSBs) using a human bronchial epithelial cell line (BEAS-2B). SSBs were assessed via the comet assay, and a novel colorimetric assay that indirectly measures SSBs repair. This assay is based on the premise that DNA SSBs induce the activation of the repair enzyme poly(ADP-ribose)polymerase, which in turn depletes intracellular NAD+/NAD(P)H (Nucleic Acids Res. 31(17):e104, 2003). We did not find any statistically significant differences in DNA SSBs between the control and iAs (1nM-10?M) treated cells with the comet and NAD(P)H assays with up to 4h exposures at 37 degrees C. In addition, no increase in SSBs was observed when the cells were exposed at 4 degrees C, which inhibits DNA repair. In these studies, H2O2 and methyl methanesulfonate induced increased SSBs. These data suggest that iAs does not directly induce an increase in SSBs in this cell line, possibly because BEAS-2B cells may be more resistant to damage than other extrapulmonary cell types shown to have increased SSBs upon iAs exposure. Furthermore, iAs can be converted in vivo to methylated organic species that may be more potent inducers of oxidative stress and SSBs. Further analyses into the possible contributions of the aforementioned factors is underway.",
Arsenic,1255523,"Use of geostatistics for remediation planning to transcend urban political boundaries Abstract: Soil remediation plans are often dictated by areas of jurisdiction or property lines instead of scientific information. This study exemplifies how geostatistically interpolated surfaces can substantially improve remediation planning. Ordinary kriging, ordinary co-kriging, and inverse distance weighting spatial interpolation methods were compared for analyzing surface and sub-surface soil sample data originally collected by the US EPA and researchers at the University at Buffalo in Hickory Woods, an industrial-residential neighborhood in Buffalo, NY, where both lead and arsenic contamination is present. Past clean-up efforts estimated contamination levels from point samples, but parcel and agency jurisdiction boundaries were used to define remediation sites, rather than geostatistical models estimating the spatial behavior of the contaminants in the soil. Residents were understandably dissatisfied with the arbitrariness of the remediation plan. In this study we show how geostatistical mapping and participatory assessment can make soil remediation scientifically defensible, socially acceptable, and economically feasible.",
Arsenic,2343445,"The Effect of Floods on Sediment Contamination in a Microtidal Coastal Lagoon: The Lagoon of Lesina, Italy Abstract: The effects on the microtidal lagoon of Lesina of runoff and the discharge of water and material from agricultural activities were investigated combining chemical analyses of pollutants [11 metals and 16 priority polycyclic aromatic compounds (PAHs)], determination of organic matter and grain size, and performance of innovative ecotoxicological tests. For metals, enrichment factors &gt;3 for arsenic, nickel, and copper (Cu) were observed in the eastern zone of the lagoon, which is affected by nearby urban activities with discharge of water and domestic waste and by agricultural input with waters rich in fertilizers. Cu was correlated with no other metal, and its high concentrations (?77 µg g(-1)) may result from the use of Cu-based fungicides in vineyards. Total PAHs (2,230 ± 3,150 ng g(-1)) displayed a wide range of concentrations with hot spots near freshwater inputs from the part of the catchment area exploited for wheat crops. Pyrolitic contamination also emerged, with higher-mass PAH congeners, such as asphalt, bitumen or coal, usually present in higher fractions as the dominant components. Ecotoxicological evaluations recorded moderate to high toxicity levels; the innovative MOT test bioassay showed good discriminatory ability because it identified a lagoon area whose inputs mainly depend on agricultural activities and which is impacted by metals rather than PAHs. Floods during periods of heavy rain and the discharge of water and material from agricultural activities may impact vulnerable systems, such as the lagoon of Lesina, where the presence of hot spots with remarkably high pollution values was observed.",
Arsenic,1021342,"Signaling pathways for arsenic-stimulated vascular endothelial growth factor-a expression in primary vascular smooth muscle cells Abstract: Chronic arsenic exposure is associated with an increased risk for cancer, cardiovascular disease (including ischemic heart disease and hypertension), peripheral vascular disease, and diabetes. Arsenic causes blood vessel growth and remodeling in vivo and cell specific, dose-dependent induction vascular endothelial growth factor-A (VEGF), which is essential for both processes. The current study examined the hypothesis that low, environmentally relevant levels of trivalent arsenic (AsIII) activate discrete signaling pathways in vascular smooth muscle cells (SMC) to induce expression of VEGF. AsIII caused a progressive increase in VEGF mRNA levels over a 48 h period in primary porcine SMC with a threshold of 1-2.5 microM. VEGF protein levels increased with a similar concentration dependence and time course. Hypoxia inducible factor-1alpha (HIF-1alpha) protein and mRNA levels also increased in response to AsIII. However, unlike the response to an iron chelator, AsIII-induced VEGF was not inhibited by siRNA directed toward HIF-1alpha. Instead, a novel protein kinase C, PKCdelta, was activated by AsIII to induce VEGF and stabilize HIF-1alpha. Consistent with this activation, AsIII caused coordinate increases in the levels of the intracellular second messenger diacyglycerol (DAG). These data suggest that AsIII induced divergent signaling pathways in SMCs that lead to independent increases in VEGF expression and HIF-1alpha signaling. However, these pathways both require initial increases in DAG levels and PKC activity.",
Arsenic,1936042,"Coordinate H3K9 and DNA methylation silencing of ZNFs in toxicant-induced malignant transformation Abstract: Genome-wide disruption of the epigenetic code is a hallmark of malignancy that encompasses many distinct, highly interactive modifications. Delineating the aberrant epigenome produced during toxicant-mediated malignant transformation will help identify the underlying epigenetic drivers of environmental toxicant-induced carcinogenesis. Gene promoter DNA methylation and gene expression profiling of arsenite-transformed prostate epithelial cells showed a negative correlation between gene expression changes and DNA methylation changes; however, less than 10% of the genes with increased promoter methylation were downregulated. Studies described herein confirm that a majority of the DNA hypermethylation events occur at H3K27me3 marked genes that were already transcriptionally repressed. In contrast to aberrant DNA methylation targeting H3K27me3 pre-marked silent genes, we found that actively expressed C2H2 zinc finger genes (ZNFs) marked with H3K9me3 on their 3' ends, were the favored targets of DNA methylation linked gene silencing. DNA methylation coupled, H3K9me3 mediated gene silencing of ZNF genes was widespread, occurring at individual ZNF genes on multiple chromosomes and across ZNF gene family clusters. At ZNF gene promoters, H3K9me3 and DNA hypermethylation replaced H3K4me3, resulting in a widespread downregulation of ZNF gene expression, which accounted for 8% of all the downregulated genes in the arsenical-transformed cells. In summary, these studies associate toxicant exposure with widespread silencing of ZNF genes by DNA hypermethylation-linked H3K9me3 spreading, further implicating epigenetic dysfunction as a driver of toxicant associated carcinogenesis.",
Arsenic,1794801,Residual central nervous system damage due to organoarsenic poisoning Abstract: ,
Arsenic,657499,"Immunotoxicity and sensitizing capacity of metal compounds depend on speciation Abstract: Immunotoxicity of metal compounds is an issue of great importance due to the recent industrial application of metals with unknown toxicity on the immune system and the discovery of metal intermediary compounds not sufficiently studied yet. In this report we show results of our study on the immunotoxicity of the following metals: the Platinum group elements (Platinum, Palladium, Rhodium), Titanium and Arsenic. We applied functional and non functional assays and investigated both innate and adaptive immune systems, in particular, cell proliferation, cytokine production by PBMCs and O*2 production by neutrophils. We obtained the following results: only some Ti compounds (Titanocene, Ti ascorbate and Ti oxalate) show immunotoxicity. Trivalent As compounds (Sodium arsenite and tetraphenyl arsonium chloride) are more immunotoxic than the other investigated As compounds. Genotoxicity of Pt group compounds is in the following order: Pt > Rh > Pd. Immunotoxicity of Pt group compounds is in the following order: Pd > Pt > Rh. Lymphocytes and macrophages show a different reaction of neutrophils to metal toxicity. We can conclude that these studies show that metal immunotoxicity depends on speciation. In general speciation provides additional and often essential information in evaluating metal toxicity. However, there are many difficulties in applying speciation in investigating toxico-kinetic aspects to many metals, mainly due to the lack of information about the existence and significance of species and to the lack of analytical methods for measuring species in biological samples.",
Arsenic,1349049,"Stress stimulates AMP-Activated protein kinase and meiotic resumption in mouse oocytes Abstract: This study examined the effects of three different cellular stresses on oocyte maturation in meiotically arrested mouse oocytes. Cumulus-cell enclosed oocytes (CEO) or denuded oocytes (DO) from immature, eCG-primed mice were cultured for 17-18 h in dbcAMP-containing medium plus increasing concentrations of the metabolic poison, sodium arsenite, or the free radical-generating agent, menadione. Alternatively, oocytes were exposed to osmotic stress by pulsing with sorbitol and returned to control inhibitory conditions for the duration of culture. Arsenite and menadione each dose-dependently induced germinal vesicle breakdown (GVB) in both DO and CEO. DO, but not CEO, pulsed for 60 min with 500 mM sorbitol were stimulated to resume maturation. The lack of effect in CEO suggests that the cumulus cells may be playing a protective role in osmotic stress-induced GVB. The AMP-activated protein kinase (PRKA; formerly known as AMPK) inhibitors, compound C and araA, completely blocked the meiosis-stimulating effects of all the tested stresses. Western blots showed that acetyl-CoA carboxylase, an important substrate of PRKA, was phosphorylated before GVB, supporting a role for PRKA in stress-induced maturation. Together, these data show that a variety of stresses stimulate GVB in meiotically arrested mouse oocytes in vitro and suggest that this effect is mediated through activation of PRKA.",
Arsenic,1357759,"Chronic Bronchitis and Emphysema Abstract: Occupationally related chronic bronchitis and emphysema are reviewed with respect to agents of causation, occupations and industries involved, worker populations at risk, epidemiology, clinical description and diagnostic criteria, pathology, methods of prevention, and research needs. Causative agents from occupational exposure include specific chemicals which produce changes in airways (ammonia (7664417), arsenic (7440382), chlorine (7782505), osmium-tetroxide (20816120), phosgene (75445), tungsten-carbide (12070121), vanadium (7440622), sulfur-dioxide (7446095), toluene-diisocyanate (26471625), and chlorinated hydrocarbons) and complex dusts that occur in industry (cotton and flax dust, coke oven emissions, cement dust, foundry dust, ceramic dust, quarry dust, tomb cutting and rock crushing operations, metal smelting, silica (7631869), asbestos (1332214) and potash (584087) exposures). Early detection of chronic bronchitis depends on symptoms of functional impairment and pulmonary function tests sensitive for early detection of hypersecretion and airways obstruction. There are no early physical or radiological signs. Diagnostic criteria for emphysema are anatomic and structural and have been shown to correlate with dyspnea, functional insufficiency, increased total lung volume, decreased diffusing capacity, increased compliance, and decreased or absent breath sounds. Prevention involves the reduction of inhalation exposure to particles. The author notes that mainline cigarette smoke represents the major exposure to be reduced. The author identifies a need for data on the prevalence of chronic bronchitis and emphysema in workers involved with ammonia fertilizers, petrochemicals, quarry work, rock crushing, and cement and brick manufacture.",
Arsenic,2088558,"Tyrosine phosphorylation of HuR by JAK3 triggers dissociation and degradation of HuR target mRNAs Abstract: In response to stress conditions, many mammalian mRNAs accumulate in stress granules (SGs) together with numerous RNA-binding proteins that control mRNA turnover and translation. However, the signaling cascades that modulate the presence of ribonucleoprotein (RNP) complexes in SGs are poorly understood. Here, we investigated the localization of human antigen R (HuR), an mRNA-stabilizing RNA-binding protein, in SGs following exposure to the stress agent arsenite. Unexpectedly, the mobilization of HuR to SGs was prevented through the activation of Janus kinase 3 (JAK3) by the vitamin K3 analog menadione. JAK3 phosphorylated HuR at tyrosine 200, in turn inhibiting HuR localization in SGs, reducing HuR interaction with targets SIRT1 and VHL mRNAs, and accelerating target mRNA decay. Our findings indicate that HuR is tyrosine-phosphorylated by JAK3, and link this modification to HuR subcytoplasmic localization and to the fate of HuR target mRNAs.",
Arsenic,628767,"Arsenite decreases CYP3A23 induction in cultured rat hepatocytes by transcriptional and translational mechanisms Abstract: Arsenic is a naturally occurring, worldwide contaminant implicated in numerous pathological conditions in humans, including cancer and several forms of liver disease. One of the contributing factors to these disorders may be the alteration of cytochrome P450 (CYP) levels by arsenic. In rat and human hepatocyte cultures, arsenic, in the form of arsenite, decreases the induction of several CYPs. The present study investigated whether arsenite utilizes transcriptional or post-transcriptional mechanisms to decrease CYP3A23 in primary cultures of rat hepatocytes. In these cultures, a 6-h treatment with 5 microM arsenite abolished dexamethasone (DEX)-mediated induction of CYP3A23 protein and activity, but did not inhibit general protein synthesis. However, arsenite treatment only reduced DEX-induced levels of CYP3A23 mRNA by 30%. The effects of arsenite on CYP3A23 transcription were examined using a luciferase reporter construct containing 1.4 kb of the CYP3A23 promoter. Arsenite caused a 30% decrease in DEX-induced luciferase expression of this reporter. Since arsenite abolished induction of CYP3A23 protein, but caused only a small decrease in CYP3A23 mRNA, the effects of arsenite on translation of CYP3A23 mRNA were investigated. Polysomal distribution analysis showed that arsenite decreased translation by decreasing the DEX-mediated increase in CYP3A23 mRNA association with polyribosomes. Arsenite did not decrease intracellular glutathione or increase lipid peroxidation, suggesting that the effect of arsenite on CYP3A23 does not involve oxidative stress. Overall, the results suggest that low-level arsenite decreases both transcription and translation of CYP3A23 in primary rat hepatocyte cultures.",
Arsenic,1021634,"Arsenicals affect base excision repair by several mechanisms Abstract: Inorganic arsenic is a strong, widespread human carcinogen. How exactly inorganic arsenic exerts carcinogenicity in humans is as yet unclear, but it is thought to be closely related to its metabolism. At exposure-relevant concentrations arsenic is neither directly DNA reactive nor mutagenic. Thus, more likely epigenetic and indirect genotoxic effects, among others a modulation of the cellular DNA damage response and DNA repair, are important molecular mechanisms contributing to its carcinogenicity. In the present study, we investigated the impact of arsenic on several base excision repair (BER) key players in cultured human lung cells. For the first time gene expression, protein level and in case of human 8-oxoguanine DNA glycosylase 1 (hOGG1) protein function was examined in one study, comparing inorganic arsenite and its trivalent and pentavalent mono- and dimethylated metabolites, also taking into account their cellular bioavailability. Our data clearly show that arsenite and its metabolites can affect several cellular endpoints related to DNA repair. Thus, cellular OGG activity was most sensitively affected by dimethylarsinic acid (DMA(V)), DNA ligase III? (LIGIII?) protein level by arsenite and X-ray cross complementing protein 1 (XRCC1 protein) content by monomethylarsonic acid (MMA(V)), with significant effects starting at ?3.2?M cellular arsenic. With respect to MMA(V), to our knowledge these effects are the most sensitive endpoints, related to DNA damage response, that have been identified so far. In contrast to earlier nucleotide excision repair related studies, the trivalent methylated metabolites exerted strong effects on the investigated BER key players only at cytotoxic concentrations. In summary, our data point out that after mixed arsenic species exposure, a realistic scenario after oral inorganic arsenic intake in humans, DNA repair might be affected by different mechanisms and therefore very effectively, which might facilitate the carcinogenic process of inorganic arsenic.",
Arsenic,1579355,"Toxicity and bioaccumulation kinetics of arsenate in two freshwater green algae under different phosphate regimes Abstract: In the present study, the toxicity and bioaccumulation kinetics of arsenate in two green algae Chlamydomonas reinhardtii and Scenedesmus obliquus under phosphate-enriched (+P) and limited (-P) conditions were investigated. P-limitation was found to aggravate arsenate toxicity and S. obliquus was more tolerant than C. reinhardtii. Such phosphate-condition-dependent or algal-species-specific toxicity difference was narrowed when the relative inhibition of cell growth was plotted against intracellular arsenate content instead of its extracellular concentration. The discrepance was further reduced when the intracellular ratio of arsenic to phosphorus was applied. It suggests that both arsenate bioaccumulation and intracellular phosphorus played an important role in arsenate toxicity. On the other hand, arsenate uptake was induced by P-limitation and its variation with ambient arsenate concentration could be well fitted to the Michaelis-Menten model. Arsenate transporters of S. obliquus were found to have a higher affinity but lower capacity than those of C. reinhardtii, which explains its better regulation of arsenate accumulation than the latter species in the toxicity experiment. Further, arsenate depuration was facilitated and more was transformed to arsenite in C. reinhardtii or under -P condition. Intracellular proportion of arsenite was also increased after the algae were transferred from the long-term uptake media to a relatively clean solution in the efflux experiment. Both phenomena imply that algae especially the sensitive species could make physiological adjustments to alleviate the adverse effects of arsenate. Overall, our findings will facilitate the application of algae in arsenate remediation.",
Arsenic,2278049,"The role of cassiterite controlling arsenic mobility in an abandoned stanniferous tailings impoundment at Llallagua, Bolivia Abstract: The surface water contamination by potentially toxic elements (PTE) leached from mine tailings is a major environmental concern. However, the formation of insoluble solid phases can control the mobility of PTE, with subsequent decrease of the risk that tailings suppose to the environment. We characterized the tailings from a tin inactive mine in Llallagua, Bolivia in order to assess the risk for surface water quality. These tailings contain high concentrations of PTE, with up to 94,344mg/kg Fe, 9135mg/kg Sn, 4606mg/kg As, 1362mg/kg Cu, 1220mg/kg Zn, 955mg/kg Pb and 151mg/kg Cd. Oxidation of sulfide minerals in these tailings generates acid leachates (pH=2.5-3.5), rich in SO4(2-) and dissolved PTE, thereby releasing contaminants to the surface waters. Nevertheless, the concentrations of dissolved Sn, As and Pb in acid leachates are low (Sn&lt;0.01mg/L; As=0.25-2.55mg/L; Pb&lt;0.05mg/L). This indicates that, for the most part, Sn, As and Pb are being retained by the solid phases in the impoundment, so that these elements are not reaching the surface waters. Fe-bearing cassiterite-an insoluble and weathering-resistant oxide mineral-is abundant in the studied tailing deposits; it should be the main solid phase controlling Sn and As mobility in the impoundment. Additionally, jarosite and plumbojarosite, identified among the secondary minerals, could also play an important role controlling the mobility of As and Pb. Taking into account (a) the low solubility constants of cassiterite (Ksp=10(-64.2)), jarosite (Ksp=10(-11)) and plumbojarosite (Ksp=10(-28.66)), and (b) the stability of these minerals under acidic conditions, we can conclude that they control the long-term fate of Sn, As and Pb in the studied tailings.",
Arsenic,1018344,"Study of in vitro cytotoxicity of a water soluble organic arsenic compound, arsenosugar, in seaweed Abstract: In the present study, we demonstrated the cytotoxic effect of a dimethylarsenic compound in seaweed, (R)-(2',3'-dihydroxypropyl) 5- deoxy-5-dimethylarsinoyl-beta-D-riboside, namely arsenosugar (AsSug), on mammalian cells, murine macrophages, in comparison with that of an inorganic arsenical, arsenite, in vitro. More than 99.5% pure AsSug was synthesized. Arsenite was strongly and equally toxic to both peritoneal macrophages (PMs) and alveolar macrophages (AMs), and the concentration of arsenite that inhibited the viability of cells by 50% compared to the viability of control cells (50% inhibitory concentration; IC50) was 5 microM. In contrast, AsSug showed no cytotoxicity to both PMs and AMs at the microM concentration level; however, it induced different and interesting cellular responses in both macrophages at high concentrations, 1-10 mM. AsSug enhanced the viability of PMs at an optimal dose of 5 mM; conversely, it showed weak but significant cytotoxicity to AMs (IC50 = 8 mM).",
Arsenic,1340697,"Toxics, Toyotas, and terrorism: the behavioral economics of fear and stigma Abstract: Economists have traditionally viewed the behavioral response to risk as continuous and proportional. In contrast, psychologists have often contended that people have little control over their response to risk that is dichotomous, nonproportional, visceral, and fear based. In extreme cases, this automatic response results in the stigmatization of a product, technology, or choice, which seemingly cannot be eliminated or reduced. In resolving these contrasting perspectives, we review four recent studies that blend behavioral economics and psychology. Together, they provide evidence for a dual-process decision model for risk that incorporates both reason and fear. They show consumers' responses to perceived risk as a mix of proportional and dichotomous (safe/unsafe) responses that are relatively more continuous in situations where deliberation is possible, and more dichotomous in emotional or stressful circumstances. These findings reconcile mixed results in past studies, and, more importantly, the dual-process model allows a clear definition of stigma, and suggests new ways to mitigate stigma and to help manage potentially damaging overreactions to it.",
Arsenic,1070321,"Associations of estimated residential soil arsenic and lead concentrations and community-level environmental measures with mother-child health conditions in South Carolina Abstract: We undertook a community-level aggregate analysis in South Carolina, USA, to examine associations between mother-child conditions from a Medicaid cohort of pregnant women and their children using spatially interpolated arsenic (As) and lead (Pb) concentrations in three geographic case areas and a control area. Weeks of gestation at birth was significantly negatively correlated with higher estimated As (r(s)=-0.28, p=0.01) and Pb (r(s)=-0.26, p=0.02) concentrations in one case area. Higher estimated Pb concentrations were consistently positively associated with frequency of black mothers (all p<0.02) and negatively associated with frequency of white mothers (all p<0.01), suggesting a racial disparity with respect to Pb.",
Arsenic,628027,"Co-administration of zinc and n-acetylcysteine prevents arsenic-induced tissue oxidative stress in male rats Abstract: Arsenic is a widespread environmental toxicant that may cause neuropathy, skin lesions, vascular lesions and cancer upon prolonged exposure. Improving nourishment like supplementation of micronutrients, antioxidants, vitamins and amino acids could be able to halve the risk in those who were previously the poor nourished. The present study was planned to investigate the preventive effects of zinc and n-acetylcysteine (NAC) supplementation either alone or in combination with arsenic on selected biochemical variables indicative of oxidative stress and liver injury in male rats. For 3 weeks 25 male wistar rats were exposed to arsenic as sodium arsenite (2 mg/kg, orally through gastric intubation) either alone or in combination with NAC (10 mg/kg, intraperitoneally), zinc (5 mg/kg, orally) or zinc plus NAC. Animals were sacrificed 24 h after the last dosing for various biochemical parameters. Concomitant administration of zinc with arsenic showed remarkable protection against blood ?-aminolevulinic acid dehydratase (ALAD) activity as well as providing protection to hepatic biochemical variables indicative of oxidative stress (like thiobarbituric acid reactive substances (TBARS) level, catalase) and tissue injury. NAC supplementation on the other hand, was moderately effective in protecting animals from the toxic effects of arsenic. Interestingly, concomitant administration of zinc and NAC was most effective compared to zinc or NAC in eliciting above-mentioned protective effects. The above results suggest significant protective value of combined zinc and NAC administration in acute arsenic exposure.",
Arsenic,1453798,"JNK and STAT3 signaling pathways converge on Akt-mediated phosphorylation of EZH2 in bronchial epithelial cells induced by arsenic Abstract: The molecular mechanisms by which arsenic (As ( 3+) ) causes human cancers remain to be fully elucidated. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of polycomb-repressive complexes 2 (PRC2) that promotes trimethylation of lysine 27 of histone H3, leading to altered expression of tumor suppressors or oncogenes. In the present study, we determined the effect of As ( 3+) on EZH2 phosphorylation and the signaling pathways important for As ( 3+) -induced EZH2 phosphorylation in human bronchial epithelial cell line BEAS-2B. The involvement of kinases in As ( 3+) -induced EZH2 phosphorylation was validated by siRNA-based gene silencing. The data showed that As ( 3+) can induce phosphorylation of EZH2 at serine 21 in human bronchial epithelial cells and that the phosphorylation of EZH2 requires an As ( 3+) -activated signaling cascade from JNK and STAT3 to Akt. Transfection of the cells with siRNA specific for JNK1 revealed that JNK silencing reduced serine727 phosphorylation of STAT3, Akt activation and EZH2 phosphorylation, suggesting that JNK is the upstream kinase involved in As ( 3+) -induced EZH2 phosphorylation. Because As ( 3+) is capable of inducing miRNA-21 (miR-21), a STAT3-regulated miRNA that represses protein translation of PTEN or Spry2, we also tested the role of STAT3 and miR-21 in As ( 3+) -induced EZH2 phosphorylation. Ectopic overexpression of miR-21 promoted Akt activation and phosphorylation of EZH2, whereas inhibiting miR-21 by transfecting the cells with anti-miR-21 inhibited Akt activation and EZH2 phosphorylation. Taken together, these results demonstrate a contribution of the JNK, STAT3 and Akt signaling axis to As ( 3+) -induced EZH2 phosphorylation. Importantly, these findings may reveal new molecular mechanisms underlying As ( 3+) -induced carcinogenesis.",
Arsenic,1022238,"An application of the holistochastic human exposure methodology to naturally occurring arsenic in Bangladesh drinking water Abstract: The occurrence of arsenic in drinking water is an issue of considerable interest. In the case of Bangladesh, arsenic concentrations have been closely monitored since the early 1990s through an extensive sampling network. The focus of the present work is methodological. In particular, we propose the application of a holistochastic framework of human exposure to study lifetime population damage due to arsenic exposure across Bangladesh. The Bayesian Maximum Entropy theory is an important component of this framework, which possesses solid theoretical foundations and offers powerful tools to assimilate a variety of knowledge bases (physical, epidemiologic, toxicokinetic, demographic, etc.) and uncertainty sources (soft data, measurement errors, etc.). The holistochastic exposure approach leads to physically meaningful and informative spatial maps of arsenic distribution in Bangladesh drinking water. Global indicators of the adverse health effects on the population are generated, and valuable insight is gained by blending information from different scientific disciplines. The numerical results indicate an increased lifetime bladder cancer probability for the Bangladesh population due to arsenic. The health effect estimates obtained and the associated uncertainty assessments are valuable tools for a broad spectrum of end-users.",
Arsenic,2345814,"Bioleaching of high pyrite carbon-rich sphalerite preflotation tailings Abstract: In this work, zinc extraction was investigated using bioleaching process. The used samples were carbon-rich preflotation tailings prepared from a lead-zinc mineral processing plant, located in Yazd province, Iran. Two samples were obtained with high amount of pyrite, while the first sample contained high arsenic (As) substitution in the pyrite crystal lattice, and it was about 4-5 times more than that of the second sample. The organic matter in both samples has presented a signature of poorly crystalline carbon. Bioleaching experiments were designed and carried out by a mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans in shake flasks. The results showed that in the optimum point of experiments (pH 1.94-2, pulp density 10 %, without initial Fe+2), about 95 % of Zn would be extracted within 14 days, while with no use of bacteria, merely 35 % of Zn content was dissolved (under the same condition). Because of the characteristics of the prepared samples, the bacterial medium (9K) was removed in the optimum condition of bioleaching tests. Results showed that even in the absence of 9K medium, bacteria had proper growth too, such that more than 93 % of Zn content was extracted. In fact, the same results were achieved in the absence and presence of 9K medium. Comparison of the obtained results in bioleaching tests under the optimum condition indicated that Zn extraction was the same for both high and low As samples, while Fe extraction from low As content sample was nearly 4 times higher than that of the other sample.",
Arsenic,62132,"Chromosome aberrations in workers exposed to arsenic Abstract: The occurrence of chromosome aberrations was studied in short-term cultured lymphocytes from nine workers exposed to arsenic at the Rönnskär smeltery in northern Sweden. In the smelter workers, 87 aberrations were found in 819 mitoses. The number of aberrations varied individually from 0 to 25 aberrations per 100 cells. In a control material 13 aberrations were found in 1012 mitoses. The frequency of chromosome aberrations was significantly increased among the smelter workers, but due to the simultaneous exposure to other agents the effect of arsenic per se can not be assessed with certainty.",
Arsenic,8702,"On the pulmonary tumorigenicity of arsenic trisulfide and calcium arsenate in hamsters Abstract: The pulmonary tumorigenicity of arsenic trisulfide and calcium arsenate was explored following 15 intratracheal instillations in male Syrian golden hamsters at weekly doses of about 3 mg/kg body weight (as arsenic). One lung adenoma appeared in 28 animals examined in the arsenic trisulfide group and 4 adenomas in 35 animals surviving the treatment with calcium arsenate. No adenomas were seen in 26 animals instilled with the vehicle (0.9% saline solution). The results show that calcium arsenate is tumorigenic (P less than 0.05), while the evidence is inconclusive for arsenic trisulfide.",
Arsenic,657864,"ERK activation in arsenite-treated G1-enriched CL3 cells contributes to survival, DNA repair inhibition, and micronucleus formation Abstract: Arsenite is known to induce chromosomal damage and extracellular signal-regulated kinases 1/2 (ERK) signaling transduction pathway. Arsenite also perturbs mitotic spindle and induces G2/M prolongation, leading to genomic instability. However, little is known concerning whether G1 phase is susceptible to arsenite in causing genomic instability and ERK activation. In this study, we investigate the roles of ERK activation in survival, micronucleus formation, and nucleotide excision repair (NER) synthesis in arsenite-treated G1-enriched CL3 human non-small-cell lung carcinoma cells. We found that G1 was the most insensitive phase to arsenite cytotoxicity, yet it was highly susceptible to arsenite in micronucleus induction. After arsenite exposure, the G1 cells exhibited a marked retard in the formation of binucleated cells when they were cultured in cytochalasin B, an inhibitor of cytokinesis, suggesting that arsenite delays the cell cycle progression. Arsenite activated sustained-ERK signal in G1 cells whose suppression further decreased cell proliferation and survival and could lower the micronucleus induction. The NER synthesis activity of G1 cells was inhibited by arsenite as a function of the extent of ERK activation. Intriguingly, blockage of ERK activation recovered NER synthesis activity in the arsenite-treated G1 cells. Together, these results suggest that ERK activation in arsenite-treated G1 cells counteracts cytotoxicity and contributes to genomic instability via NER synthesis inhibition and micronucleus induction.",
Arsenic,1026443,"Arsenic groundwater contamination and its health effects in the state of Uttar Pradesh (UP) in upper and middle Ganga plain, India: A severe danger Abstract: This communication presents results of our 2-year survey on groundwater arsenic contamination in three districts Ballia, Varanasi and Gazipur of Uttar Pradesh (UP) in the upper and middle Ganga plain, India. Analyses of 4,780 tubewell water samples revealed that arsenic concentrations in 46.5% exceeded 10 microg/L, in 26.7%, 50 microg/L and in 10% 300 microg/L limits. Arsenic concentrations up to 3,192 microg//L were observed. The age of tubewells (n=1,881) ranged from less than a year to 32 years, with an average of 6.5 years. Our study shows that older tubewells had a greater chance of contamination. Depth of tubewells (n=3,810) varied from 6 to 60.5 m with a mean of 25.75 m. A detailed study in three administrative units within Ballia district, i.e. block, Gram Panchayet, and village was carried out to assess the magnitude of the contamination. Before our survey the affected villagers were not aware that they were suffering from arsenical toxicity through contaminated drinking water. A preliminary clinical examination in 11 affected villages (10 from Ballia and 1 from Gazipur district) revealed typical arsenical skin lesions ranging from melanosis, keratosis to Bowens (suspected). Out of 989 villagers (691 adults, and 298 children) screened, 137 (19.8%) of the adults and 17 (5.7%) of the children were diagnosed to have typical arsenical skin lesions. Arsenical neuropathy and adverse obstetric outcome were also observed, indicating severity of exposure. The range of arsenic concentrations in hair, nail and urine was 137-10,900, 764-19,700 microg/kg, and 23-4,030 microg/L, respectively. The urine, hair and nail concentrations of arsenic correlated significantly (r=0.76, 0.61, and 0.55, respectively) with drinking water arsenic concentrations. The similarity to previous studies on arsenic contamination in West Bengal, Bihar and Bangladesh indicates that people from a significant part of the surveyed areas in UP are suffering and this will spread unless drives to raise awareness of arsenic toxicity are undertaken and an arsenic safe water supply is immediately introduced.",
Arsenic,2345681,"Removing arsenic from groundwater in Cambodia using high performance iron adsorbent Abstract: In Cambodia, groundwater has been contaminated with arsenic, and purification of the water is an urgent issue. From 2010 to 2012, an international collaborative project between Japan and Cambodia for developing arsenic-removing technology from well water was conducted and supported by the foundation of New Energy and Industrial Technology Development Organization, Japan. Quality of well water was surveyed in Kandal, Prey Veng, and Kampong Cham Provinces, and a monitoring trial of the arsenic removal equipment using our patented amorphous iron (hydr)oxide adsorbent was performed. Of the 37 wells surveyed, arsenic concentration of 24 exceeded the Cambodian guideline value (50 ?g L(-1)), and those of 27 exceeded the WHO guideline for drinking water (10 ?g L(-1)). Levels of arsenic were extremely high in some wells (&gt;1,000-6,000 ?g L(-1)), suggesting that arsenic pollution of groundwater is serious in these areas. Based on the survey results, 16 arsenic removal equipments were installed in six schools, three temples, two health centers, four private houses, and one commune office. Over 10 months of monitoring, the average arsenic concentrations of the treated water were between 0 and 10 ?g L(-1) at four locations, 10-50 ?g L(-1) at eight locations, and &gt;50 ?g L(-1) at four locations. The arsenic removal rate ranged in 83.1-99.7 %, with an average of 93.8 %, indicating that the arsenic removal equipment greatly lower the risk of arsenic exposure to the residents. Results of the field trial showed that As concentration of the treated water could be reduced to &lt;10 µg L(-1) by managing the As removal equipment properly, suggesting that the amorphous iron (hydr)oxide adsorbent has high adsorbing capacity for As not only in the laboratory environment but also in the field condition. This is one of the succeeding As removal techniques that could reduce As concentration of water below the WHO guideline value for As in situ.",
Arsenic,1354988,"Arsenic content, fractionation, and ecological risk in the surface sediments of lake Abstract: ",
Arsenic,1337743,"Bioavailability of arsenic, cadmium, iron and zinc in leafy vegetables amended with urban particulate matter suspension Abstract: BACKGROUND: Urban particulate matter (PM) can affect green plants either via deposition on the above-ground biomass, where the contaminants can penetrate the leaf surface, or indirectly via soil-root interaction. This experiment assessed the potential risk of PM-derived risk elements contained in vegetables. The bioavailable portions of arsenic (As), cadmium (Cd), iron (Fe), and zinc (Zn) in leafy vegetables amended by PM via soil and/or foliar application were investigated in a model pot experiment, in which lettuce and chard were cultivated. RESULTS: By using the physiologically based extraction test simulating in vitro human digestive processes in the stomach and small intestine, the bioavailable portions of toxic elements from PM-amended plant biomass were extracted. Extractable portions of elements by a simulated gastric solution from biomass decreased for lettuce in the order Zn &gt; Cd &gt; As &gt; Fe; while for chard, the order was As &gt; Zn &gt; Cd &gt; Fe. No significant effects of PM physical fractions or soil were observed. CONCLUSIONS: Although the bioavailable element portions in the PM samples were lower compared to plants, the bioavailable element contents in foliar PM-amended plant leaves exceeded the control and soil PM amendment levels, even after biomass washing.",
Arsenic,2278364,"Bioremediation of arsenic-contaminated water: Recent advances and future prospects Abstract: Arsenic contamination of groundwater and surface water is widespread throughout the world. Considering its carcinogenicity and toxicity to human and animal health, remediation of arsenic-contaminated water has become a high priority. There are several physicochemical-based conventional technologies available for removing arsenic from water. However, these technologies possess a number of limitations such as high cost and generation of toxic by-products, etc. Therefore, research on new sustainable and cost-effective arsenic removal technologies for water has recently become an area of intense research activity. Bioremediation technology offers great potential for possible future application in decontamination of pollutants from the natural environment. It is not only environmentally friendly but cost-effective as well. This review focuses on the state-of-art knowledge of currently available arsenic remediation methods, their prospects, and recent advances with particular emphasis on bioremediation strategies.",
Arsenic,2278238,"Biochemical effects of arsenic stress in the leaves of halophyte Cakile maritima (Scop.) plants under salinity Abstract: The aim of the study was to determine the biochemical responses which were not investigated before, the combined effects of arsenic and salt stress in the leaves of Cakile maritima (Scop.). Therefore, product of lipit peroxidation (MDA, malondialdehyde), proline content , non-protein thiol, ascorbate, dehydroascorbate and the activity of some antioxidant enzymes as ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6) were reported. The MDA content was increased at 24 h but it was more at 96 h under salt stress alone. Otherwise the combined effect of arsenic and salt stress increased the malondialdehyde content at 24 h more than salt stress alone. APX activity was not changed under all treatment while CAT enzyme was decreased at 24 h. The proline content was increased only at 96 h under salt stress alone while it did not change under arsenic and salt stress. Nevertheless, the ascorbate content was not changed under all treatments. The ratio of ascorbate/dehydroascorbate was decreased at 24 h but not significiantly at 96 h under salinity. Otherwise it was decreased at 24 h and increased at 96 h under arsenic and salt treatment lead to reduction of the increased MDA content according to 24 h. From these results, it can be suggested that salinity with arsenic stress induced oxidative damage more seriously than salt stress alone with unchanged enzymatic and non enzymatic antioxidants in the leaves of Cakile maritima is a plant succulent halophyte.",
Arsenic,1337296,"Synthesis and characterization of multi-amino-functionalized cellulose for arsenic adsorption Abstract: A multi-amino adsorbent for arsenic adsorption was reported in this paper. Glycidyl methacrylate (GMA) was first grafted onto the surface of cotton cellulose using ceric ammonium nitrate (CAN) as the initiator, and then the introduced epoxy groups reacted with tetraethylenepentamine (TEPA) to obtain a multi-amino adsorbent. The adsorbent was characterized by FTIR, elemental analysis, (13)C NMR and SEM. Then, the adsorption of arsenic for this adsorbent was investigated. The results showed that the GMA and TEPA were successfully grafted onto the surface of cellulose, and the modification improved the arsenic adsorption performances. Kinetic study suggested that the chemisorptions were the rate-limiting step. Among the three adsorption isotherm models used, Langmuir model fitted the experimental data best. The adsorption capacities of arsenic were less affected by coexisting ions. The adsorbent could be effectively regenerated for four cycles with 0.1mol/L NaOH solution.",
Arsenic,2149354,"Arsenic in the different environmental compartments of Switzerland: an updated inventory Abstract: Switzerland has three main areas with elevated natural arsenic concentrations : 1) the northern part, where a number of thermal mineral springs are located, 2) the Jura mountains with iron-rich limestone and clays and 3) the Alps, where arsenic-bearing ore deposits and silicate rock aquifers are found. In addition in the Alps, there are also isolated arsenic-bearing thermal and mineral springs. A complete survey of all public drinking water supplies carried out between 1997 and 2002 showed that about 20'000 people lived in areas with arsenic between 10 and 50 mg/L in spring waters and a few hundred depended on waters with As between 50 and 180 mg/L. In the meanwhile, most communities have access to drinking water &lt;2 mg/L. In most cases the waters were well oxygenated and the arsenic was in its pentavalent form (arsenate). In flooded soils rich in organic matter (forest, wetlands), with reducing conditions and elevated dissolved iron, trivalent arsenite predominated. The origin of these naturally contaminated waters is in As-bearing rocks and soils, in which the As is most often located in sulfides (pyrite, arsenopyrite) and Fe-oxyhydroxides. They either occur as dm-m-sized veins or disseminated in areas of several hundred meters. Only very little contamination can be attributed to waste materials, such as mine dumps or old industrial waste repositories. Plants growing on As-rich soils usually contain less than 5 mg/kg As. Monitoring data for mosses suggests that dust particles rich in As can locally contribute to a week air pollution. The only available study on the relation of As-concentrations in drinking water and cancer incidence did not give significant results.",
Arsenic,1329881,"Sequential treatment by ionizing radiation and sodium arsenite dramatically accelerates TRAIL-mediated apoptosis of human melanoma cells Abstract: Melanoma is the most lethal form of skin cancer. There is a lack of effective treatments for individuals with advanced disease. Many melanomas exhibit high levels of radioresistance. The direct consequence of gamma-irradiation for most melanoma cells is growth arrest at the G2-M phase of cell cycle. However, radiation-induced signaling pathways may affect numerous additional targets in cancer cells. We show in the present study that gamma-irradiation, as well as alpha-particle exposure, dramatically increases the susceptibility of melanoma cells to recombinant tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis via up-regulation of surface TRAIL-receptor 1/receptor 2 (DR4/DR5) levels and to Fas ligand-mediated apoptosis via up-regulation of surface Fas levels. Additionally, increased dynamin-2 expression after irradiation is critically important in the translocation of death receptor to the cell surface. Moreover, sodium arsenite treatment may up-regulate expression of endogenous TRAIL and induces its translocation to cell surface and further down-regulates cFLIP levels in melanoma cells. We have evaluated the effects of sequential gamma-irradiation and arsenite treatment of melanoma cells for the induction of death signaling. Such treatment results in an efficient TRAIL-mediated apoptosis via a paracrine mechanism. These data highlight the efficacy of combined modality treatment involving radiation and arsenite in clinical management of this often fatal form of skin cancer.",
Arsenic,1519087,"Air Pollution Study in Croatia Using Moss Biomonitoring and ICP-AES and AAS Analytical Techniques Abstract: Moss biomonitoring technique was applied in a heavy-metal pollution study of Croatia in 2006 when this country participated in the European moss survey for the first time. This survey was repeated in 2010, and the results are presented in this study. For this purpose, 121 moss samples were collected during summer and autumn 2010. The content of 21 elements was determined by inductively coupled plasma-atomic emission spectrometry and atomic absorption spectrometry. Principal component analyses was applied to show the association between the elements. Six factors (F1-F6) were determined, of which two are anthropogenic (F3 and F6), two are mixed geogenic-anthropogenic (F1 and F5), and two are geogenic factors (F2 and F4). Geographical distribution maps of the elements over the sampled territory were constructed using geographic information systems technology. Comparison of the median values of some of the anthropogenic elements-such as arsenic, cadmium, chromium, copper, mercury, nickel, lead, vanadium, and zinc-with those from the 2006 study shows that anthropogenic pollution has changed insignificantly during the last 5 years. The data obtained in the investigation in Norway are taken for comparison with pristine area, which indicates that Croatia is somewhat polluted but still, shows a more favourable picture when compared with two neighbouring countries.",
Arsenic,1508625,"Arsenic levels in drinking water and mortality of liver cancer in Taiwan Abstract: The carcinogenic effect of arsenic is well documented, but epidemiologic data on liver cancer were limited. To evaluate the dose-response relationship between arsenic in drinking water and mortality of liver cancer, we conducted a study in 138 villages in the southwest coast area of Taiwan. We assessed arsenic levels in drinking water using data from a survey conducted by the government and reviewed death certificates from 1971 to 1990 to identify liver cancer cases. Using village as the unit, we conducted multi-variate regression analyses and then performed post hoc analyses to validate the findings. During the 20-year period, 802 male and 301 female mortality cases of liver cancer were identified. After adjusting for age, arsenic levels above 0.64mg/L were associated with an increase in the liver cancer mortality in both genders, but no significant effect was observed for lower exposure categories. Post hoc analyses and a review of literature supported these findings. We concluded that exposures to high arsenic levels in drinking water are associated with the occurrence of liver cancer, but such an effect is not prominent at exposure levels lower than 0.64mg/L.",
Arsenic,1033555,"Asbestos, smoking, and laryngeal carcinoma Abstract: This study was designed to examine the relationship between exposure to asbestos and laryngeal cancer. A retrospective study of 43 pairs of patients with laryngeal cancer and their matched controls examined a number of variables, including smoking, exposure to asbestos, and other occupational factors. Patients with laryngeal cancer and the controls were matched for age, sex, and place of residence. The data indicate a substantial association between asbestos exposure and laryngeal cancer. Cigarette smoking was also associated with the disease, although the strength of association was not as high as that for asbestos. Exposure to uranium, chromium, nickel, cobalt, arsenic, x-rays, and alcohol did not appear related to later development of carcinoma of the larynx. We conclude that exposure to asbestos and cigarette smoking are potent factors in the development of this disease.",
Arsenic,1033471,Levels of arsenic in alcohol-related liver disease Abstract: Increased levels of arsenic were found in serum and urine and in hair and nails of patients suffering from alcohol-related liver disease (ALD). Various surveys were conducted in different places to find the cause for high arsenic in ALD. It was found that patients were consuming 'home made brew' which was contaminated with arsenic.,
Arsenic,2343434,"Arsenic speciation in newberyite (MgHPO4•3H2O) determined by synchrotron XAS and EPR spectroscopy: Implications for the fate of arsenic in green fertilizers Abstract: Newberyite (MgHPO4•3H2O), a biomineral and common constituent in guano deposits, is an important decomposition product of struvite that is an increasingly popular green fertilizer recovered from wastewaters. Two samples of newberyite containing 1099 and 25 ppm As have been obtained at pH = 6.4, by using Na2HAsO4•7H2O and NaAsO2 as the dopant, respectively (i.e. Synthesis #1 and #2). Synchrotron arsenic K-edge X-ray absorption spectroscopic data of newberyite from Synthesis #1 show that As5+ is dominant and has a local environment typical of the arsenate species. Single-crystal electron paramagnetic resonance (EPR) spectra of gamma-ray-irradiated newberyite from Synthesis #1 contain two arsenic-associated oxyradicals: [AsO3]2- and [AsO2]2- derived from As5+ and As3+, respectively, at the P site. Quantitative analyses of powder EPR spectra allow determinations of the As5+ and As3+ contents in newberyite from Synthesis #1 and #2. Elevated concentrations of arsenic also occur in natural newberyite transformed from struvite in guano deposits and record the accumulation of this metalloid in the food chain. Therefore, newberyite, which sequesters As during crystallization and retains this metalloid during the transformation from struvite, can attenuate arsenic contamination from green fertilizers in moderately acidic soils. Also, the capacity for accommodating both As5+ and As3+ in the crystal lattice coupled with simple chemistry and easy crystallization at ambient conditions makes newberyite an attractive material for remediation of arsenic contamination in aqueous environments.",
Arsenic,1327628,"Sodium arsenite-induced chromosomal aberrations in the Xq arm of Chinese hamster cell lines Abstract: Non-cytotoxic concentrations (1.5, 3 and 6 microM) of sodium arsenite (SA) were used to study its cytogenetic effects with special reference to the frequency and nature of chromosomal aberrations on the X chromosome at Xq21 and at centromeric regions in CHO9, EM-C11, V79, V-H4 and CHE cell lines using Giemsa and FISH techniques. A high frequency of chromosomal breakpoints was distributed on the X chromosome localized at the secondary constriction region of the q arm (Xq21) and to a lesser degree at the centromeric region (c band-positive region), showing a high degree of fragility of these regions. This phenomenon was observed in all cell lines except for V79, where aberrations were localized only in the Xq21 region, and CHO9, where the observed breakage frequency was lowest in comparison with other cell lines and breaks were mostly located in the centromeric region rather than at Xq21. Homozygous expression of the breakpoint at Xq21 (fragile site) and in the centromeric region was also confirmed using a female Chinese hamster embryonic (CHE) cell line, which showed a similar high frequency of breakpoints at Xq21 and in the centromeric region of both X chromosomes. Further, a detailed cytogenetic study in CHO9 and its ligase-deficient mutant EM-C11 cell line showed slightly higher sensitivity to SA in a cell survival assay. No difference was found for chromosomal aberrations in Giemsa stained preparations. For SCEs a higher spontaneous frequency was evident in EMC-11. SA significantly increased the frequency of SCEs in CHO9, but no effect was found in EM-C11. Further, we observed an increased number of abnormal cells with pulverised chromosomes, decondensed chromatin, isochromosomes and hyperploidy in CHO9 and EM-C11 cell lines at all doses of SA.",
Arsenic,2064202,"Chemical constituents of fine particulate air pollution and pulmonary function in healthy adults: The Healthy Volunteer Natural Relocation study Abstract: The study examined the associations of 32 chemical constituents of particulate matter with an aerodynamic diameter ?2.5?m (PM2.5) with pulmonary function in a panel of 21 college students. Study subjects relocated from a suburban area to an urban area with changing ambient air pollution levels and contents in Beijing, China, and provided daily morning/evening peak expiratory flow (PEF) and forced expiratory volume in 1s (FEV1) measurements over 6 months in three study periods. There were significant reductions in evening PEF and morning/evening FEV1 associated with various air pollutants and PM2.5 constituents. Four PM2.5 constituents (copper, cadmium, arsenic and stannum) were found to be most consistently associated with the reductions in these pulmonary function measures. These findings provide clues for the respiratory effects of specific particulate chemical constituents in the context of urban air pollution.",
Arsenic,2064294,"Structural characterization and vibrational spectroscopy of the arsenate mineral wendwilsonite Abstract: In this paper, we have investigated on the natural wendwilsonite mineral with the formulae Ca2(Mg,Co)(AsO4)2?2(H2O). Raman spectroscopy complimented with infrared spectroscopy has been used to determine the molecular structure of the wendwilsonite arsenate mineral. A comparison is made with the roselite mineral group with formula Ca2B(AsO4)2?2H2O (where B may be Co, Fe(2+), Mg, Mn, Ni, Zn). The Raman spectra of the arsenate related to tetrahedral arsenate clusters with stretching region shows strong differences between that of wendwilsonite and the roselite arsenate minerals which is attributed to the cation substitution for calcium in the structure. The Raman arsenate (AsO4)(3-) stretching region shows strong differences between that of wendwilsonite and the roselite arsenate minerals which is attributed to the cation substitution for calcium in the structure. In the infrared spectra complexity exists of multiple to tetrahedral (AsO4)(3-) clusters with antisymmetric stretching vibrations observed indicating a reduction of the tetrahedral symmetry. This loss of degeneracy is also reflected in the bending modes. Strong Raman bands around 450cm(-1) are assigned to ?4 bending modes. Multiple bands in the 350-300cm(-1) region assigned to ?2 bending modes provide evidence of symmetry reduction of the arsenate anion. Three broad bands for wendwilsonite found at 3332, 3119 and 3001cm(-1) are assigned to OH stretching bands. By using a Libowitzky empirical equation, hydrogen bond distances of 2.65 and 2.75Å are estimated. Vibrational spectra enable the molecular structure of the wendwilsonite mineral to be determined and whilst similarities exist in the spectral patterns with the roselite mineral group, sufficient differences exist to be able to determine the identification of the minerals.",
Arsenic,1017213,"Exposure to Pb, Cd, and As mixtures potentiates the production of oxidative stress precursors: 30-day, 90-day, and 180-day drinking water studies in rats Abstract: Exposure to chemical mixtures is a common and important determinant of toxicity and is of particular concern due to their appearance in sources of drinking water. Despite this, few in vivo mixture studies have been conducted to date to understand the health impact of chemical mixtures compared to single chemicals. Interactive effects of lead (Pb), cadmium (Cd) and arsenic (As) were evaluated in 30-, 90-, and 180-day factorial design drinking water studies in rats designed to test the hypothesis that ingestion of such mixtures at individual component Lowest-Observed-Effect-Levels (LOELs) results in increased levels of the pro-oxidant delta aminolevulinic acid (ALA), iron, and copper. LOEL levels of Pb, Cd, and As mixtures resulted in the increased presence of mediators of oxidative stress such as ALA, copper, and iron. ALA increases were followed by statistically significant increases in kidney copper in the 90- and 180-day studies. Statistical evidence of interaction was identified for six biologically relevant variables: blood delta aminolevulinic acid dehydratase (ALAD), kidney ALAD, urinary ALA, urinary iron, kidney iron, and kidney copper. The current investigations underscore the importance of considering interactive effects that common toxic agents such as Pb, Cd, and As may have upon one another at low-dose levels. The interactions between known toxic trace elements at biologically relevant concentrations shown here demonstrate a clear need to rigorously review methods by which national/international agencies assess health risks of chemicals, since exposures may commonly occur as complex mixtures.",
Arsenic,81737,"Elimination of interferences in the determination of arsenic and selenium in biological samples by inductively coupled plasma mass spectrometry Abstract: The determination of As and Se in biological samples by inductively coupled plasma mass spectrometry is well known to be degraded by spectral interferences. The resolution of quadrupole mass analysers is insufficient to resolve As+ and Se+ ions from polyatomic species such as ArCl+, ArAr+ and So+3. A study of this problem in human serum also revealed substantial non-spectral interferences on these elements occuring in the presence of organic compounds. It is shown that both problems can easily be overcome by a combination of chemical modification (addition of 4% ethanol) with nebulizer flow-rate gas adjustment. Under these conditions the use of standard additions for calibration allowed As and Se to be determined accurately in samples of biological origin. The method developed was applied to human serum and urine and for both As and Se excellent agreement with certified values was obtained.",
Arsenic,2088314,Robust Structure and Reactivity of Aqueous Arsenous Acid-Platinum(II) Anticancer Complexes Abstract: ,
Arsenic,50839,"Lead poisoning due to hai ge fen: the porphyrin content of individual erythrocytes Abstract: A 45-year-old Korean man developed abdominal colic, muscle pain, and fatigue. Following a 3-week hospitalization, acute intermittent porphyria was diagnosed based on the symptoms and a high level of urinary delta-aminolevulinic acid (378 mumol/L [4.95 mg/dL]). However, discovery of an elevated blood lead level (3.7 mumol/L [76 micrograms/dL]) subsequently led to the correct diagnosis. No occupational source of lead exposure was identified. The patient reported ingesting a Chinese herbal preparation for 4 weeks prior to becoming ill. A public health investigation revealed that the source of lead exposure was hai ge fen (clamshell powder), one of the 36 ingredients of the Chinese herbal medicine. We used fluorescence image-based cytometry to determine the frequency distribution of the zinc protoporphyrin content in circulating red blood cells and found that 70% of the patient's cells contained elevated levels of zinc protoporphyrin, consistent with the duration of lead exposure and effect of lead on heme synthesis. Analysis of zinc protoporphyrin content in circulating red blood cell distributions may be useful in the diagnosis, therapy, and kinetic modeling of lead poisoning. Environmental lead poisoning is best addressed through the close collaboration of clinicians, public health specialists, and laboratory scientists.",
Arsenic,1017276,"Maternal and fetal exposure to four carcinogenic environmental metals Abstract: <strong>OBJECTIVE: </strong>To examine maternal and fetal exposure levels to four carcinogenic metals, arsenic (As), cadmium (Cd), nickel (Ni), and beryllium (Be), and to investigate their environmental influences.<br /><br /><strong>METHODS: </strong>Metal concentrations in maternal and umbilical cord blood were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Environmental factors that might play a role in exposure were analyzed using Mann-Whitney nonparametric U-tests and multiple linear regression.<br /><br /><strong>RESULTS: </strong>The concentrations of As, Cd, and Ni in umbilical cord blood (5.41, 0.87, and 139.54 ?g/L) were significantly lower than those in maternal blood (6.91, 1.93, and 165.93 ?g/L). There were significant positive correlations between the maternal and cord concentrations of each carcinogen. Our results showed that: (i) exposures to potentially harmful occupational factors during pregnancy were associated with high levels of maternal As, Cd, and Ni; (ii) living close to major transportation routes (&lt;500 m) or exposure to second-hand smoke during pregnancy increased the maternal Cd levels and (iii) living close to industrial chimneys induced high maternal Ni levels. Multiple linear regression analysis showed that these environmental factors remained significant in models of the influences of these four carcinogens.<br /><br /><strong>CONCLUSION: </strong>Both mothers and fetuses had been exposed to As, Cd, Ni, and Be. The increased levels of these carcinogens in pregnant women were associated with some detrimental environmental factors, such as occupational exposure, contact with second-hand smoke and living close to major transportation routes or industrial chimneys.",
Arsenic,1936034,"Chronic kidney disease of uncertain aetiology: Prevalence and causative factors in a developing country Abstract: <strong>BACKGROUND: </strong>This study describes chronic kidney disease of uncertain aetiology (CKDu), which cannot be attributed to diabetes, hypertension or other known aetiologies, that has emerged in the North Central region of Sri Lanka.<br /><br /><strong>METHODS: </strong>A cross-sectional study was conducted, to determine the prevalence of and risk factors for CKDu. Arsenic, cadmium, lead, selenium, pesticides and other elements were analysed in biological samples from individuals with CKDu and compared with age- and sex-matched controls in the endemic and non-endemic areas. Food, water, soil and agrochemicals from both areas were analysed for heavy metals.<br /><br /><strong>RESULTS: </strong>The age-standardised prevalence of CKDu was 12.9% (95% confidence interval [CI] = 11.5% to 14.4%) in males and 16.9% (95% CI = 15.5% to 18.3%) in females. Severe stages of CKDu were more frequent in males (stage 3: males versus females = 23.2% versus 7.4%; stage 4: males versus females = 22.0% versus 7.3%; P < 0.001). The risk was increased in individuals aged >39 years and those who farmed (chena cultivation) (OR [odds ratio] = 1.926, 95% CI = 1.561 to 2.376 and OR = 1.195, 95% CI = 1.007 to 1.418 respectively, P < 0.05). The risk was reduced in individuals who were male or who engaged in paddy cultivation (OR = 0.745, 95% CI = 0.562 to 0.988 and OR = 0.732, 95% CI = 0.542 to 0.988 respectively, P < 0.05). The mean concentration of cadmium in urine was significantly higher in those with CKDu (1.039 mug/g) compared with controls in the endemic and non-endemic areas (0.646 mug/g, P < 0.001 and 0.345 mug/g, P < 0.05) respectively. Urine cadmium sensitivity and specificity were 70% and 68.3% respectively (area under the receiver operating characteristic curve = 0.682, 95% CI = 0.61 to 0.75, cut-off value >=0.397 mug/g). A significant dose--effect relationship was seen between urine cadmium concentration and CKDu stage (P < 0.05). Urine cadmium and arsenic concentrations in individuals with CKDu were at levels known to cause kidney damage. Food items from the endemic area contained cadmium and lead above reference levels. Serum selenium was <90 mug/l in 63% of those with CKDu and pesticides residues were above reference levels in 31.6% of those with CKDu.<br /><br /><strong>CONCLUSIONS: </strong>These results indicate chronic exposure of people in the endemic area to low levels of cadmium through the food chain and also to pesticides. Significantly higher urinary excretion of cadmium in individuals with CKDu, and the dose--effect relationship between urine cadmium concentration and CKDu stages suggest that cadmium exposure is a risk factor for the pathogensis of CKDu. Deficiency of selenium and genetic susceptibility seen in individuals with CKDu suggest that they may be predisposing factors for the development of CKDu.",
Arsenic,1020370,"Differential activation of the c-Jun N-terminal kinase pathway in arsenite-induced apoptosis and sensitization of chemically resistant compared to susceptible B-lymphoma cell lines Abstract: Various forms of inorganic arsenic are significant environmental contaminants that have multiple effects on cells, including the induction of apoptotic cell death. Induction of apoptosis in lymphoid cells can mediate immunotoxicity following exposure to chemicals. However, the mechanisms regulating the sensitivity of B-lymphocytes to arsenic-induced apoptosis are not understood. Therefore, we investigated the involvement of key mitogen-activated protein kinase pathways and apoptosis induction by sodium arsenite in a model system of chemically resistant and susceptible B-lymphoma cell lines. These studies revealed a differential requirement for the c-Jun N-terminal kinase (JNK) pathway for apoptosis induction by sodium arsenite in the resistant EW36 versus sensitive ST486 cell lines. Specifically, activation of the JNK pathway was not required for arsenite-induced apoptosis in ST486 cells, whereas JNK pathway activation was always associated with apoptosis induction in EW36 cells. Importantly, we found that EW36 cells, which overexpress the Bcl-2 protein, can be substantially sensitized to arsenite-induced apoptosis by prior exposure to nonlethal hyperthermia. Moreover, pretreatment with an inhibitor of p38 kinase acted synergistically with hyperthermia to further sensitize EW36 cells. The inhibition of p38 prolonged a transient period of JNK phosphorylation that occurred immediately after heat shock treatment and involved the persistent activation of SEK1, one of the kinases upstream of JNK. Significantly, the sensitization of resistant cells is characterized by a lowering of the threshold concentration of arsenite required to activate the JNK pathway and induce apoptosis.",
Arsenic,1019385,"Activation analyses of authenticated hairs of Napoleon Bonaparte confirm arsenic poisoning Abstract: In 1960, activation analyses at the Harwell Nuclear Research Laboratory of the University of Glascow, London of authenticated hairs of Napoleon Bonaparte taken immediately after his death confirmed Napoleon's chronic arsenic poisoning on the island of St. Helena. Timeline correlation of his clinical symptomatology of the preceding 4 months, as reported in the written diaries of his exiled companions, further supports the effect of fluctuating, elevated toxic levels of arsenic on his health. Independent analyses of authenticated hairs of Napoleon by the Toxicology Crime Laboratory of the United States Federal Bureau of Investigation in 1995 reveals toxic levels of arsenic. The successful assassination of Napoleon included both a cosmetic and lethal phase. The cosmetic phase consisted of arsenic poisoning over time to weaken Napoleon, making the associated debility appear to be a natural illness and thus allay any suspicions prior to instituting the lethal phase. On May 3, 1821, at 5:30 P.M., the lethal phase was carried out. Napoleon was given Calomel (HgCl), a cathartic, and a popular orange-flavored drink called orgeat, which was flavored with the oil of bitter almonds. Together they formed mercury cyanide, which is lethal. Napoleon lost consciousness and died two days later.",
Arsenic,2064174,"Arsenic sequestration in iron plaque and its effect on As uptake by rice plants grown in paddy soils with high contents of As, iron oxides, and organic matter Abstract: ",
Arsenic,1352010,"Arsenic ingestion and health effects in Bangladesh: Epidemiological observations Abstract: This paper discusses exposure to arsenic in drinking water and its relation to some novel chronic health effects, namely diabetes mellitus and hypertension, as well as to the well-known skin manifestations. Four villages in Bangladesh were identified as mainly dependent on wells potentially contaminated with arsenic. A total of 1481 subjects in these villages, greater than or equal to30 years of age and of both genders, were identified as exposed to arsenic. All these individuals were interviewed and examined for blood pressure, skin lesions, and glucosuria. Arsenic levels in drinking water ranged from non-detectable to 2040 mug/l and exposure was expressed as time-weighted concentrations. Urine samples from the study subjects were tested by glucometric strip and positive tests were considered to be cases of glucosuria. Hypertension was defined as a systolic blood pressure greater than or equal to140 mm Hg in combination with a diastolic blood pressure of greater than or equal to90 mm Hg. Out of the 1481 exposed individuals, 430 exhibited keratosis, i.e., the overall prevalence of skin lesions was 29% in the studied villages. After adjustment for age, sex, and BMI, the prevalence ratio (or risk) of 1.6 was obtained for hypertension in exposed subjects with skin lesions, as compared to those lacking lesions. Likewise the prevalence ratio of 1.8 was found for glucosuria in exposed subjects with skin lesions after adjustment by age, sex, and BMI. Significant trends in risk (P < 0.001) were observed between exposure to arsenic and glucosuria and hypertension, respectively, which strengthens the likelihood of a causal association of these conditions with arsenic exposure.",
Arsenic,2088463,"The C-terminal domain of the bacteriophage T4 terminase docks on the prohead portal clip region during DNA packaging Abstract: Bacteriophage ATP-based packaging motors translocate DNA into a pre-formed prohead through a dodecameric portal ring channel to high density. We investigated portal-terminase docking interactions at specifically localized residues within a terminase-interaction region (aa279-316) in the phage T4 portal protein gp20 equated to the clip domain of the SPP1 portal crystal structure by 3D modeling. Within this region, three residues allowed A to C mutations whereas three others did not, consistent with informatics analyses showing the tolerated residues are not strongly conserved evolutionarily. About 7.5nm was calculated by FCS-FRET studies employing maleimide Alexa488 dye labeled A316C proheads and gp17 CT-ReAsH supporting previous work docking the C-terminal end of the T4 terminase (gp17) closer to the N-terminal GFP-labeled portal (gp20) than the N-terminal end of the terminase. Such a terminase-portal orientation fits better to a proposed &quot;DNA crunching&quot; compression packaging motor and to portal determined DNA headful cutting.",
Arsenic,2345797,"Toxicity of urban highway runoff in Shanghai to Zebrafish (Danio rerio ) embryos and luminous bacteria (Vibrio qinghaiensis.Q67) Abstract: Pollution from urban highway runoff has been identified as one of the major causes of the deterioration of receiving water quality. The purpose of this study is to assess the toxicity of urban storm water samples in Shanghai using the zebrafish (Danio rerio ) embryo test and the bacterial luminescence (Vibrio qinghaiensis ) assay. The toxicity of highway runoff from seventeen storm events was investigated in both grab and composite samples. Zebrafish embryos were exposed to the runoff samples and development parameters including lethality, spontaneous movements in 20 s, heart beat rate, hatching rate, and abnormality of zebrafish embryos were observed after 24, 48, 72, and 96 h of exposure. Inhibition rates of luminescence intensity were also recorded. The results showed that in the zebrafish embryo toxicity tests, both grab and composite samples increased the lethality, reduced the percentage with spontaneous movements and heart beats, inhibited the hatching of embryos, and induced morphological abnormalities. In the Vibrio qinghaiensis toxicity test, all the grab samples inhibited the luminescence, while some of the composite samples promoted it, which indicated that different types of toxicants might have been affecting the species. The multivariate statistics analysis indicated that heavy metal (zinc, manganese, and copper) and PAHs might mainly contribute to the toxicity of runoff samples.",
Arsenic,1359628,"Metabolism of inorganic arsenic-74 in humans following oral ingestion Abstract: HEEP COPYRIGHT: BIOL ABS. Oral doses of carrier-free 74As ( 6 muCi/man;nic acid were administered to 6 adult males. Some (58%) of the 74As dose was excreted in the urine in the first 5 days after dosing. The proportion of chemical species of arsenic in the urine was as follows: 51% dimethylarsinic acid, 21% monomethylarsenic compound and 27% inorganic As.",
Arsenic,8678,"Intracellular interaction and biotransformation of arsenite in rats and rabbits Abstract: The accumulation of arsenic with time in tissues of rats and rabbits was determined by neutron activation analysis (NAA). Rats showed a steady increase in the As-concentrations with age, whereas in rabbits it was nearly the same for adults and in young animals. The metabolism of arsenic was studied in both animal species after i.p. injection of 50/micrograms As/kg b.w. as 74As labelled arsenite. Eight tissues, as well as blood and urine, were analysed for 74As content after 16 and 48 hours. The binding of 74As to hematic and intracellular components and the chemical forms of arsenic in tissues and urine were investigated. In the plasma and the RBC-fraction of the rabbit, the As concentration decreased during the first two days, while in the rats it only disappeared from the plasma, but was retained in the RBC-fraction. Liver, kidney and lung of rabbits with the highest As concentrations at 16 and 48 hours showed a rapid clearance of As in the first 48 hours. In the corresponding tissues of the rats, the rate of decline was significantly lower, due to the higher binding of 74As to tissue constituents. Poor binding of As to plasma proteins was seen in rabbits while in rats it was totally bound to this fraction. In the RBC, liver and kidney cytosols, however, the affinity of As for intracellular proteins was higher in both animal species but characterized by a rate of binding different between the two animal species. The amount of dimethylarsinic acid (DMA) in the tissues was significantly lower in the rat than in the rabbit, reflecting the total amount of diffusible arsenic, which was also much lower in the tissues of rats than in rabbits.",
Arsenic,1031529,"Arsenic enhances matrix metalloproteinase-14 expression in fibroblasts Abstract: This study focused on the effects of arsenic (As) on fibroblast-derived matrix metalloproteinase (MMP)-2 and -14 levels, as these proteins were reported to be associated with tumor progression. Arsenic was found to promote production of the fibroblast-derived active form of MMP-2. Further, As at 100 or 1000 microM increased MMP-14 expression levels in fibroblasts. In addition, 1000 microM mercury (Hg) but not As increased pro-MMP-2 protein, which is involved in the conversion of the proenzyme into its active form. Since MMP-14 is an activator of pro-MMP-2, data suggest that As promotes production of fibroblast-derived active form of MMP-2 through increased expression of MMP-14. Evidence indicates that As appeared to be less effective than Hg in the conversion of pro-MMP-2 into its active form.",
Arsenic,1337347,"Response of rice genotype to straighthead disease as influenced by arsenic level and water management practices in soil Abstract: Arsenic (As) uptake by rice plants and the straighthead disease induced by As-based herbicide are of environmental concerns. Bioavailability or mobility of inorganic As in soil has been reported to be significantly influenced by soil minerals such as iron (hydr) oxide; however, the interactions of organic As such as monosodium methanearsonate (MSMA) with soil minerals are little studied, thus largely unknown. In an effort to minimize the As uptake by rice and determine rice cultivar response to soil MSMA level, a field experiment was conducted on three rice cultivars grown in both MSMA-treated and -untreated soils under continuous or intermittent flood water management practices. Results indicated that the grain yield and the occurrence of straighthead disease were cultivar-dependent and influenced by soil As level and water management practices. Straighthead-resistant cultivars yielded more and had lower grain As than the susceptible ones. Elevated soil As with continuous flood management significantly reduced the grain yield of susceptible cultivars by &gt;89% due to substantially increased straighthead, which were induced by increased As content in grains. Yield reduction by MSMA treatment could be partially mitigated with intermittent flood water practice. The As accumulation was found to be associated with soil iron redox transformation influenced by the water management. This study demonstrates that the selection of less As-susceptible cultivars and intermittent flood water practice could be effective means to lower the As accumulation in grains and minimize the occurrence of the As-induced straighthead symptom and yield reduction.",
Arsenic,1579336,"Can physiological endpoints improve the sensitivity of assays with plants in the risk assessment of contaminated soils? Abstract: Site-specific risk assessment of contaminated areas indicates prior areas for intervention, and provides helpful information for risk managers. This study was conducted in the Ervedosa mine area (Bragança, Portugal), where both underground and open pit exploration of tin and arsenic minerals were performed for about one century (1857 - 1969). We aimed at obtaining ecotoxicological information with terrestrial and aquatic plant species to integrate in the risk assessment of this mine area. Further we also intended to evaluate if the assessment of other parameters, in standard assays with terrestrial plants, can improve the identification of phytotoxic soils. For this purpose, soil samples were collected on 16 sampling sites distributed along four transects, defined within the mine area, and in one reference site. General soil physical and chemical parameters, total and extractable metal contents were analyzed. Assays were performed for soil elutriates and for the whole soil matrix following standard guidelines for growth inhibition assay with Lemna minor and emergence and seedling growth assay with Zea mays. At the end of the Z. mays assay, relative water content, membrane permeability, leaf area, content of photosynthetic pigments (chlorophylls and carotenoids), malondialdehyde levels, proline content, and chlorophyll fluorescence (Fv/Fm and ?PSII) parameters were evaluated. In general, the soils near the exploration area revealed high levels of Al, Mn, Fe and Cu. Almost all the soils from transepts C, D and F presented total concentrations of arsenic well above soils screening benchmark values available. Elutriates of several soils from sampling sites near the exploration and ore treatment areas were toxic to L. minor, suggesting that the retention function of these soils was seriously compromised. In Z. mays assay, plant performance parameters (other than those recommended by standard protocols), allowed the identification of more phytotoxic soils. The results suggest that these parameters could improve the sensitivity of the standard assays.",
Arsenic,2149085,"Arsenic toxicosis in sheep: The first report from Iran Abstract: Arsenic contamination of groundwater has been previously reported in Ghopuz, a village located in the Northwest of Iran. Samples were taken from consuming and irrigation water and plants of the region for chemical analysis. A seven-year old ewe, which had lived in and fed a lifelong at the same place, with clinical signs such as weakness, wasting and inappropriate integument was necropsied. Grossly, buccal erosion, stomatitis, cutaneous ulcers and serous atrophy of fat deposits were observed. Rumen contents, wool and several tissue samples were obtained for toxicological and histopathological examinations. Mean arsenic concentration in the spring water, irrigation water and grass/algae were 70.11, 48.74 and 141.85 ppb (µg/kg), respectively. Arsenic levels were 486.73, 247.94, 127.92, 125.97 and 231.24 ppb in wool, skin, rumen contents, liver and kidney, respectively. Microscopic study revealed hyperemia and heavy parasitic infestation of the abomasal wall. Hyperemia and regeneration of renal tubule epithelia were observed in kidneys and hyperkeratosis, suppurative deep dermatitis and paniculitis were found in skin. Periacinar fibrosis and a poorly differentiated cholangiocarcinoma were seen in liver. In pancreas, reduced cell density of islands of Langerhans was noticeable. In the central nervous system, perineuronal and perivascular edema, ischemic changes in gray matter neurons, and microcavitation of white matter were present. Our findings confirmed chronic arsenic toxicosis in small ruminants in this region. It can be concluded that long-term consumption of arsenic contamined water and forage may be associated with chronic arsenic poisoning in domestic animals and human beings, with consequent neoplastic disease and induction of diabetes in this region.",
Arsenic,1070424,"Inhibition of the Heat Shock Response by PI103 Enhances the Cytotoxicity of Arsenic Trioxide Abstract: Heat-shock factor 1 (HSF1) is a key regulator of the cytoprotective and anti-apoptotic heat shock response and can be activated by arsenite. Inhibition of HSF1 activation may therefore enhance the cytotoxicity of arsenic trioxide (ATO). We show that ATO induced HSF1 phosphorylation at serine 326 (S326) and induced HSF1-dependent expression of heat shock proteins (HSPs) 27 and 70 in cultured cells. HSF1 significantly reduced cell sensitivity to ATO by reducing apoptosis. Disruption of HSF1 function not only reduced ATO induction of HSP27 and 70 but enhanced ATO cytotoxicity by elevating apoptosis. These results reveal that HSF1 activation and the resulting induction of HSPs may protect cells from ATO cytotoxicity. The diminished expression of HSPs and hypersensitivity to ATO in cells stably depleted of HSF1 was rescued by ectopic expression of wild-type HSF1 but not an S326A substitution mutant, indicating that phosphorylation at S326 was critical for the protective effect of HSF1. Simultaneous treatment of cells with ATO and PI103, an inhibitor of members of the phosphatidylinositol 3-kinase (PI3K) family, suppressed not only ATO-induced expression of an HSP70 promoter-reporter construct and endogenous HSP70 but also phosphorylation of HSF1 S326. PI103 considerably reduced HSF1 transactivation in ATO-treated cells but had only a limited effect on HSF1 nuclear translocation and DNA binding. Furthermore, PI103 enhanced ATO cytotoxicity in an HSF1-dependent manner. Thus, inhibition of S326 phosphorylation by PI103 blocks the transactivation of HSF1 and may consequently suppress ATO induction of the heat shock response and sensitize cells to ATO.",
Arsenic,2346021,"Simultaneous determination of phthalates, their metabolites, alkylphenols and bisphenol A using GC-MS in urine of men with fertility problems Abstract: A GC-MS method was successfully applied to measure simultaneously the concentrations of endocrine disrupting compounds (5 dialkyl phthalates, 9 phthalate monoesters, 3 alkylphenols and bisphenol A) in 136 male urine samples. In the present study the method was validated and concentrations of EDCs were determined. The results were compared with results from other studies. Correlations between endocrine disrupting compounds and also correlations of endocrine disrupting compounds with two semen quality parameters are presented and evaluated. Significant positive correlations were found between almost all the endocrine disrupting compounds. The parameter sum of DEHP (SUM DEHP) was positively correlated to all the endocrine disrupting compounds but negatively to two semen quality parameters. Negative correlations between the endocrine disrupting compounds and the semen quality parameters could indicate that endocrine disrupting compounds could cause reproductive problems by decreasing the semen count and quality. This research will have helped to evaluate human exposure to endocrine disrupting compounds.",
Arsenic,1579339,"Isolation and characterization of two novel alkalitolerant sulfidogens from a Thiopaq bioreactor, Desulfonatronum alkalitolerans sp. nov., and Sulfurospirillum alkalitolerans sp. nov Abstract: Two obligately anaerobic sulfidogenic bacterial strains were isolated from the full-scale Thiopaq bioreactor in Lelystad (The Netherlands) removing H2S from biogas under oxygen-limiting and moderately haloalkaline conditions. Strain HSRB-L represents a dominant culturable sulfate-reducing bacterium in the reactor. It utilizes formate, H2 (with acetate as C-source) and lactate as e-donors, and sulfate, thiosulfate and sulfite as e-acceptors. It is haloalkalitolerant, with a pH range for lithotrophic growth from 7.5 to 9.7 (optimum at 8.5-9) and a salt range from 0.1 to 1.75 M total Na(+) (optimum at 0.6 M). The strain is a member of the genus Desulfonatronum and is proposed as a novel species D. alkalitolerans. The second strain, strain HTRB-L1, represents a dominant thiosulfate/sulfur reducer in the reactor. It is an obligate anaerobe utilizing formate and H2 (with acetate as C-source), lactate, pyruvate and fumarate as e-donors, and thiosulfate (incomplete reduction), sulfur, arsenate and fumarate as e-acceptors. With lactate as e-donor it also grows as an ammonifyer in the presence of nitrate and nitrite. HTRB-L1 is haloalkalitolerant, with a pH range for lithotrophic growth from 7.1 to 9.7 (optimum at 8.5) and a salt range from 0.6 to 1.5 M total Na(+) (optimum at 0.6 M). Phylogenetic analysis showed that strain HTRB-L1 is a novel species within the genus Sulfurospirillum (Epsilonproteobacteria) for which a name Sulfurospirillum alkalitolerans is proposed.",
Arsenic,1597380,"Electrochemical As(III) whole-cell based biochip sensor Abstract: The development of a whole-cell based sensor for arsenite detection coupling biological engineering and electrochemical techniques is presented. This strategy takes advantage of the natural Escherichia coli resistance mechanism against toxic arsenic species, such as arsenite, which consists of the selective intracellular recognition of arsenite and its pumping out from the cell. A whole-cell based biosensor can be produced by coupling the intracellular recognition of arsenite to the generation of an electrochemical signal. Hereto, E. coli was equipped with a genetic circuit in which synthesis of beta-galactosidase is under control of the arsenite-derepressable arsR-promoter. The E. coli reporter strain was filled in a microchip containing 16 independent electrochemical cells (i.e. two-electrode cell), which was then employed for analysis of tap and groundwater samples. The developed arsenic-sensitive electrochemical biochip is easy to use and outperforms state-of-the-art bacterial bioreporters assays specifically in its simplicity and response time, while keeping a very good limit of detection in tap water, i.e. 0.8ppb. Additionally, a very good linear response in the ranges of concentration tested (0.94ppb to 3.75ppb, R(2)=0.9975 and 3.75 ppb to 30ppb, R(2)=0.9991) was obtained, complying perfectly with the acceptable arsenic concentration limits defined by the World Health Organization for drinking water samples (i.e. 10ppb). Therefore, the proposed assay provides a very good alternative for the portable quantification of As (III) in water as corroborated by the analysis of natural groundwater samples from Swiss mountains, which showed a very good agreement with the results obtained by atomic absorption spectroscopy.",
Arsenic,1025123,"A low-cost method to identify tubewells for longitudinal research on arsenic in groundwater Abstract: Exposure to high concentrations of arsenic in tubewell groundwater from the shallow aquifers of Bangladesh could result in up to 300,000 arsenic-related cancer cases over the next four decades. Understanding the magnitude and temporal dynamics of this exposure, via longitudinal studies, is imperative for planning effective mitigation and management strategies. Appropriate methods are needed to identify tubewells for longitudinal sampling. A plastic band marked with a unique identification number was developed, and various methods for attaching the band to the tubewell were tested, resulting in the choice of a galvanized-iron split-rivet. Two follow-up surveys at two and 14 months post-banding assessed the durability and longevity under field conditions in the JiVitA Project area in rural, northwestern Bangladesh. After two months, approximately 96.0% of the original bands on 1,063 tubewells were functional, although the rivets were partially corroded. After 14 months, approximately 65% of a subsample of the bands were functional. With further improvements to the rivets, these bands offer an inexpensive, durable, enumeration technology for longitudinal studies on groundwater arsenic.",
Arsenic,1343345,Changes in erythropoiesis in normal mice induced by transplantation of peritoneal cells from syngeneic donors with long-term sodium arsenite intoxication Abstract: ,
Arsenic,710850,"Arsenic-induced suicidal erythrocyte death Abstract: Environmental exposure to arsenic has been associated with anemia, which could result from suicidal erythrocyte death or eryptosis, characterized by cell shrinkage and phosphatidylserine exposure at the erythrocyte surface. Eryptosis is triggered by increase in cytosolic Ca2+ concentration, ceramide and energy depletion. The present experiments explored, whether arsenic stimulates eryptosis. According to annexin V-binding, arsenic trioxide (7 microM) within 48 h significantly increased phosphatidylserine exposure of human erythrocytes without inducing hemolysis. According to forward scatter, arsenic trioxide (7 microM) significantly decreased cell volume. Moreover, Fluo3-fluorescence showed that arsenic (10 microM) significantly increased cytosolic Ca2+ concentration. According to binding of respective fluorescent antibodies, arsenic trioxide (10 microM) significantly increased ceramide formation. Arsenic (10 microM) further lowered the intracellular ATP concentration. Removal of extracellular Ca2+ or inhibition of the Ca2+-permeable cation channels with amiloride blunted the effects of arsenic on annexin V-binding and cell shrinkage. In conclusion, arsenic triggers suicidal erythrocyte death by increasing cytosolic Ca2+ concentration, by stimulating the formation of ceramide and by decreasing ATP availability.",
Arsenic,735057,"Sodium arsenite induces ROS generation, DNA oxidative damage, HO-1 and c-Myc proteins, NF-?B activation and cell proliferation in human breast cancer MCF-7 cells Abstract: Epidemiological evidence has associated exposure to arsenic (As) in drinking water with an increased incidence of human cancers in the skin, bladder, liver, kidney and lung. Sodium arsenite mimics the effects of estradiol and induces cell proliferation in the estrogen responsive breast cancer cell line MCF-7. Therefore, our aim was to further explore the ability of sodium arsenite to induce MCF-7 epithelial breast cell proliferation and some of its underlying mechanisms by studying ROS production, c-Myc and HO-1 protein levels, 8-OHdG formation and NF-kappaB activation. Low arsenite concentrations (0.5-5 microM) induced ROS production and ROS-related depolarization of the mitochondrial membrane suggesting that mitochondria played an important role in the oxidative effects of As. ROS-mediated DNA damage as measured by the presence of 8-OHdG DNA-adducts in their nuclei, IkappaB phosphorylation, NF-kappaB activation and increases in c-Myc and HO-1 protein levels were also observed, suggesting that these factors play a relevant role in the arsenite induced MCF-7 cell recruitment into the S-phase of the cell cycle and cell proliferation observed. In conclusion, arsenite activates several pathways involved in MCF-7 cell proliferation suggesting that arsenite exposure may pose a risk for breast cancer in human exposed populations notwithstanding that most studies to date have not yet implicated this metalloid as a cofactor in the etiology of this disease.",
Arsenic,628654,"Functional characterization of two variant human GSTO 1-1s (Ala140Asp and Thr217Asn) Abstract: Glutathione-S-transferase class Omega (GSTO 1-1) belongs to a new subfamily of GSTs, which is identical with human monomethylarsonic acid (MMA(V)) reductase, the rate limiting enzyme for biotransformation of inorganic arsenic, environmental carcinogen. Recombinant GSTO 1-1 variants (Ala140Asp and Thr217Asn) were functionally characterized using representative substrates. No significant difference was observed in GST activity towards 1-chloro-2,4-dinitrobenzene, whereas thioltransferase activity was decreased to 75% (Ala140Asp) and 40% (Thr217Asn) of the wild-type GSTO 1-1. For MMA(V) reductase activity, the Ala140Asp variant exhibited similar kinetics to wild type, while the Thr217Asn variant had lower Vmax (56%) and Km (64%) values than the wild-type enzyme. The different activities of the enzyme variants may influence both the intracellular thiol status and arsenic biotransformation. This can help explain the variation between individuals in their susceptibility to oxidative stress and inorganic arsenic.",
Arsenic,1022536,"Activation of Nrf2 and accumulation of ubiquitinated A170 by arsenic in osteoblasts Abstract: Sub-lethal levels of arsenic induce upregulation of stress proteins. We here report for the first time that inorganic arsenic activates the transcription factor Nrf2, which controls the expression of oxidative stress-induced proteins. Treatment of cultured MC3T3-E1 osteoblasts with arsenite or arsenate induced increase of Nrf2, followed by transcriptional activation of target genes encoding HO-1, Prx I, and A170. We found that arsenate (200-800 micro M) only slightly increased the normal 60kDa A170 protein but markedly increased higher molecular mass forms of A170 (HMM-A170) that appeared as smeared bands. Arsenate also markedly increased ubiquitin-conjugated cellular proteins, suggesting that HMM-A170 was one of the poly-ubiquitinated proteins. Arsenite (50-100 micro M) also induced accumulation of HMM-A170 and ubiquitin-conjugated proteins. These results provide the first direct evidence that toxic arsenics impair the normal function of A170. Our findings provide a potential diagnostic tool for monitoring biotoxicity in cells and tissues in response to arsenic compounds.",
Arsenic,2337078,"Irrigating with arsenic contaminated groundwater in West Bengal and Bangladesh: A review of interventions for mitigating adverse health and crop outcomes Abstract: There is a rich body of literature on arsenic (As) contamination of groundwater and its consequences for human health via drinking water. Less is known however, on the impacts that flow from the use of arsenic rich groundwater for irrigation or the effectiveness of arsenic remediation in agricultural systems. To partially fill this gap, we review 29 studies that examine the consequences of irrigating with arsenic contaminated groundwater and 28 studies which evaluate interventions aimed at reducing its negative impacts on human health and crops. These studies are geographically limited to West Bengal and Bangladesh (Bengal plains) as these regions constitute hubs of concerns for groundwater contamination. These studies show that there are six broad categories of interventions: deficit irrigation; soil fertilization; growing alternative field crops (other than paddy); switching to arsenic tolerant paddy cultivars; cooking methods to reduce arsenic content in rice and nutritional supplements. Importantly, these efforts target different stages of the agri-food system, some intervene in production processes and balance concerns for crop yields and human health while others focus on consumption practices and only mitigate health risks. Despite this diversity in focus, our results indicate that all treatments have positive effects, either in reducing As content in grains, its accumulation in soil and/or increase crop yields compared to control groups. However, the extent of these impacts varies as do their implications for long-term agricultural sustainability. From a policy perspective, these interventions offer promising alternatives to the extremes of restricted groundwater use on the one hand, and unregulated extraction on the other, but are yet to be integrated into mainstream extension services. (c) 2014 Elsevier B.V. All rights reserved.",
Arsenic,1015991,"Aberrant cell proliferation by enhanced mitochondrial biogenesis via mtTFA in arsenical skin cancers Abstract: Arsenic-induced Bowen's disease (As-BD), a cutaneous carcinoma in situ, is thought to arise from gene mutation and uncontrolled proliferation. However, how mitochondria regulate the arsenic-induced cell proliferation remains unclear. The aim of this study was to clarify whether arsenic interfered with mitochondrial biogenesis and function, leading to aberrant cell proliferation in As-BD. Skin biopsy samples from patients with As-BD and controls were stained for cytochrome c oxidase (Complex IV), measured for mitochondrial DNA (mtDNA) copy number and the expression levels of mitochondrial biogenesis-related genes, including peroxisome proliferator-activated receptor gamma coactivator-1? (PGC-1?), nuclear respiratory factor 1 (NRF-1), and mitochondrial transcription factor A (mtTFA). The results showed that expression of cytochrome c oxidase, mtTFA, NRF-1, and PGC-1? was increased in As-BD compared with in healthy subjects. Treatment of primary keratinocytes with arsenic at concentrations lower than 1.0 ?mol/L induced cell proliferation, along with enhanced mitochondrial biogenesis. Furthermore, we observed that the mitochondrial oxygen consumption rate and intracellular ATP level were increased in arsenic-treated keratinocytes. Blocking of mitochondrial function by oligomycin A (Complex V inhibitor) or knockdown of mtTFA by RNA interference abrogated arsenic-induced cell proliferation without affecting cyclin D1 expression. We concluded that mtTFA up-regulation, augmented mitochondrial biogenesis, and enhanced mitochondrial functions may contribute to arsenic-induced cell proliferation. Targeting mitochondrial biogenesis may help treat arsenical cancers at the stage of cell proliferation.",
Arsenic,1704085,Efficient adsorption of As(V) on poly(acrylo-amidino ethylene amine) nanofiber membranes Abstract: ,
Arsenic,734889,"Assessing airborne PM-bound arsenic exposure risk in semiconductor manufacturing facilities Abstract: The purpose of this study was to investigate the inhalation risks on the workers (operator and administrator) exposure to airborne particulate matter-bound arsenic (PMAs) in semiconductor manufacturing facilities. We reanalyzed published empirical data of the personal exposure levels and size distributions of airborne PMAs and linked a human respiratory tract model to calculate the concentrations deposited in target lung regions. We used a physiologically based pharmacokinetic model with a dose-response relationship based on an empirical three-parameter Hill equation model to simulate the exposure time-dependent arsenic dose profiles in human tissues and to estimate quantitatively the inhalation exposure risks. Results show that the threshold level of As(III) for lipid peroxidation response (LPO) on human lung epithelial cells was estimated to be 11.89 (95% CI: 8.09-15.69) microM, whereas 16.39 (95% CI: 12.56-20.22) microM for oxidative DNA damage on human dermal cells. Risk analysis shows that the LPO responses were estimated to be 3.79 (95% CI: 2.44-5.33) for operator and 0.03 (95% CI: 0.01-0.10) for administrator at a risk of 0.5. The 10% probability (risk=0.1) of human dermal cells affected by oxidative DNA damage responses is approximately 27.21% (95% CI: 12.71-67.02%) for operator and 0.03% (95% CI: 0.01-0.07%) for administrator. This study suggests that a potential link between inhalation exposure risk of operator to airborne PMAs in semiconductor manufacturing workplace.",
Arsenic,1255649,"Archaeal diversity: temporal variation in the arsenic-rich creek sediments of Carnoulès Mine, France Abstract: The Carnoulès mine is an extreme environment located in the South of France. It is an unusual ecosystem due to its acidic pH (2-3), high concentration of heavy metals, iron, and sulfate, but mainly due to its very high concentration of arsenic (up to 10 g L(-1) in the tailing stock pore water, and 100-350 mg L(-1) in Reigous Creek, which collects the acid mine drainage). Here, we present a survey of the archaeal community in the sediment and its temporal variation using a culture-independent approach by cloning of 16S rRNA encoding genes. The taxonomic affiliation of Archaea showed a low degree of biodiversity with two different phyla: Euryarchaeota and Thaumarchaeota. The archaeal community varied in composition and richness throughout the sampling campaigns. Many sequences were phylogenetically related to the order Thermoplasmatales represented by aerobic or facultatively anaerobic, thermoacidophilic autotrophic or heterotrophic organisms like the organotrophic genus Thermogymnomonas. Some members of Thermoplasmatales can also derive energy from sulfur/iron oxidation or reduction. We also found microorganisms affiliated with methanogenic Archaea (Methanomassiliicoccus luminyensis), which are involved in the carbon cycle. Some sequences affiliated with ammonia oxidizers, involved in the first and rate-limiting step in nitrification, a key process in the nitrogen cycle were also observed, including Candidatus Nitrososphaera viennensis and Candidatus nitrosopumilus sp. These results suggest that Archaea may be important players in the Reigous sediments through their participation in the biochemical cycles of elements, including those of carbon and nitrogen.",
Arsenic,2347721,"Synthesis, characterization, and adsorptive properties of magnetic cellulose nanocomposites for arsenic removal Abstract: In this study, the magnetic cellulose nanomaterials, containing magnetic nanoscale zerovalent iron (nZVI) and cellulose, were prepared by a novel reduction method and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The XRD and XPS results demonstrated the formation of zerovalent iron nanoparticles in the nanocomposite materials. With a saturation magnetization of 57.2 emu g-1, the cellulose@nZVI composites could be easily separated from solutions in 30 s through the external magnetic field. We investigated the adsorption performance of the magnetic cellulose nanomaterials for As(III) removal from aqueous solutions. The experimental results showed that arsenite adsorption followed the pseudo-second-order kinetic model and Langmuir isotherm model. A maximum removal of 99.27 % was observed for an initial concentration 10 mg L-1, at pH 8.0, and an adsorbent dose of 1.0 g L-1. Considering the high adsorption capacity, fast adsorption rate, and quick magnetic separation from treated water, the cellulose@nZVI composites were expected to be an efficient magnetic adsorbent for arsenic removal from aqueous solutions.",
Arsenic,2345683,"Arsenic speciation in Australian-grown and imported rice on sale in australia: implications for human health risk Abstract: Rice is an important route of arsenic (As) exposure to humans, especially populations with rice-based diets. Human health risk of As varies greatly with rice variety and country of origin. The purpose of the present study was to determine total and speciated As in Australian-grown and imported rice on sale in Australia to assess their health risk to consumers. The total As (tAs) concentrations in Australian-grown organic brown, medium grain brown, and organic white rice were 438 ± 23, 287 ± 03, and 283 ± 18 ?g kg(-1) dry weight (d wt), respectively. In Bangladeshi, Indian, Pakistani, and Thai rice imported and on sale in Australia, tAs concentrations were 56 ± 05, 92 ± 10, 82 ± 06 and 172 ± 24 ?g kg(-1), respectively. Asian rice contained mainly inorganic As (iAs; 86-99%), whereas 18-26% of the tAs in Australian-grown rice was dimethylarsinic acid (DMA). Relatively higher concentrations of tAs in Australian-grown rice than that in imported rice of Asian origin suggest that Australian-grown rice may be a health risk for the consumers. It was estimated that Australian-grown organic brown rice can contribute up to 98% of the FAO/WHO recommended maximum tolerable daily intake limit of iAs (2.1 ?g kg(-1) body wt day(-1)) for Asian immigrants. However, other Australian consumers including European immigrants are unlikely to be at risk to As from rice diets due to their lower rice consumption rates than that of Asian immigrants. The risk assessment showed that imported rice on sale in Australia was likely to pose a lower health risk to consumers than Australian-grown rice.",
Arsenic,627564,"Interactive alterations of arsenic and malathion in the disposition kinetics of pefloxacin Abstract: Assessment of deleterious effects produced by concurrent exposure to commonly encountered chemicals is of great concern to find out toxicological consequences arising as a result of their interactions and for a more comprehensive management of chemical-induced untoward effects. The naturally occurring heavy metal arsenic is present in food and water. Malathion is one of the most widely used pesticides in agriculture and public health practices worldwide. Humans, animals, and birds are exposed to these chemicals through environmental processes. Since arsenic and malathion are shown to exert an inhibitory effect on cytochrome P450 activities, their continuous exposure may alter the disposition kinetics of drugs that are predominantly metabolized hepatically. The current study was undertaken to evaluate the impact of subchronic exposure of arsenic, malathion, and their combination on the disposition kinetics of widely used fluoroquinolone antimicrobial pefloxacin in chickens. Broiler chickens were exposed to either arsenic (50 ppm), malathion (500 ppm), or arsenic (50 ppm) plus malathion (500 ppm). Arsenic and malathion were given in drinking water and feed, respectively. Following 28 days of exposure, all birds received a single oral dose of pefloxacin (10 mg/kg) and the plasma concentrations and the disposition kinetic parameters of the drug were determined. In the birds not exposed to arsenic and/or malathion, the elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), maximum plasma drug concentration (C(max)), mean residence time (MRT), and bioavailability of pefloxacin were 8.46 +/- 0.24 h, 39.06 +/- 1.13 microg.h.ml(-1), 2.69 +/- 0.19 microg.ml(-1), 12.29 +/- 0.48 h, and 60.52 +/- 1.74%, respectively. Exposure to arsenic was associated with a significant increase in C(max) (4.28 +/- 0.45 microg.ml(-1)) and a nonsignificant increase in the values of AUC (48.96 +/- 2.55 microg.h.ml(-1)) and bioavailability (74.55 +/- 3.8 %) of pefloxacin. The values of AUC (51.62 +/- 4.76 microg.h.ml(-1)), t(1/2beta) (12.57 +/- 1.26 h), MRT (19.94 +/- 1.99 h), and bioavailability (78.59 +/- 7.25 %) of pefloxacin were significantly increased in malathion-exposed birds. Concomitant exposure to arsenic and malathion did not affect the disposition kinetic variables of pefloxacin. The study shows that subchronic malathion exposure significantly alters the elimination kinetics of pefloxacin. Following concurrent exposure, arsenic nullifies the malathion-induced changes in disposition kinetics of pefloxacin by possibly diminishing the cytochrome P450-catalyzed bioactivation of malathion.",
Arsenic,1597325,"Effect of silicate supplementation on the alleviation of arsenite toxicity in 93-11 (Oryza sativa L. indica) Abstract: Chronic exposure to arsenic (As) in rice has raised many health and environmental problems. As reported, great variation exists among different rice genotypes in As uptake, translocation, and accumulation. Under hydroponic culture, we find that the Chinese wild rice (Oryza rufipogon; acc. 104624) takes up the most arsenic among tested genotypes. Of the cultivated rice, the indica cv. 93-11 has the lowest arsenic translocation factor value but accumulates the maximum concentration of arsenic followed by Nipponbare, Minghui 86, and Zhonghua 11. Higher level of arsenite concentration (50 ?M) can induce extensive photosynthesis and root growth inhibition, and cause severe oxidative stress. Interestingly, external silicate (Si) supplementation has significantly increased the net photosynthetic rate, and promoted root elongation, as well as strongly ameliorated the oxidative stress by increasing the activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and peroxidase in roots and/or leaves of 93-11 seedlings. Notably, 1.873 mM concentration of Si considerably decreases the total As uptake and As content in roots, but significantly increases the As translocation from roots to shoots. In contrast, Si supplementation with 1.0 mM concentration significantly increases the total As uptake and As concentrations in roots and shoots of 93-11 seedlings after 50 ?M arsenite treatment for 6 days.",
Arsenic,627075,"Dyanmic regulation and involvement of the heat shock transcriptional response in arsenic carcinogenesis Abstract: The objective of this study is to better define induction of the heat shock response by arsenite, and to evaluation if induction of heat shock proteins (HSPs) contributes to the carcinogenic activity of arsenite. We show here that arsenite is a ubiquitous inducer of the heat shock response in mammalian cells: that it activated heat shock transcription factor 1 (HSF1) DNA-binding activity, enhanced hsp 70 promoter, and induced hsp70mRNA and synthesis of HSP chaperones. Using a high throughput hsp70 promoter-luciferase reporter assay, we observed a hormetic dose response where low concentrations of arsenite stimulated and high concentrations inhibited. Further, the response was time-dependent such that with longer times of incubation, the dose response shifted to the left. The effect of arsenite in inducing the hsp 70-luciferase reporter absolutely required a functional HSF1 as it was not observed in HSF1 minus cells but re-instated by expression of HSF1. Consistent with the suggestion that arsenic targets vicinal cysteine-SH, we showed that dithiothreitol blocked the effect of arsenite. Assays of cell viability and caspase showed that arsenite caused a dose-dependent increase in cell death by activation of caspase 3/7 and pre-induction of HSPs blunted these effects. Using anchorage independent cell growth as a late stage tumor promotion assay, we showed that low concentrations of arsenite had a growth promoting effect, which was enhanced by moderate heat shock. Our study provides evidence that induction of the heat shock response is a sensitive biomarker of arsenic exposure and that induction of HSPs likely contributes to the tumor promotion effect of arsenic.",
Arsenic,710979,"Low-dose synergistic immunosuppression of T-dependent antibody responses by polycyclic aromatic hydrocarbons and arsenic in C57BL/6J murine spleen cells Abstract: Polycyclic aromatic hydrocarbons (PAHs) and arsenic are both environmental agents that are known to have significant immunotoxicity. Previous studies have shown that PAH exposure of spleen cells in vitro produces significant immune suppression of humoral immunity, especially when P450 activation products are examined. Exposure to arsenic, particularly sodium arsenite, has also been found to be suppressive to antibody responses in vitro and in vivo. The purpose of the present studies was to examine the immunotoxicity of PAHs and arsenite following coexposures with the theory being that the agents may exert synergistic actions, which might be based on their different mechanisms of action. Spleen cells were isolated from male C57BL/6J wild-type mice and treated with PAHs and/or arsenic (arsenite or arsenate). Immunotoxicity assays were used to assess the T-dependent antibody response (TDAR) to sheep red blood cells (SRBCs), measured by a direct plaque-forming cell (PFC) assay. Cell viability was measured by trypan blue staining. Spleen cell viability was not altered following 4 days of PAH and/or arsenic treatment. However, the TDAR demonstrated suppression by both PAHs and arsenic in a concentration-dependent manner. p53 was also induced by NaAsO(2) (As(3)(+)) and PAHs alone or in combination. The PAHs and their metabolites investigated included benzo[a]pyrene (BaP), BaP-7,8-diol, BaP-7,8-diol-9,10-epoxide (BPDE), 7,12-dimethylbenz[a]anthracene (DMBA), DMBA-3,4-diol, dibenzo[a,l]pyrene (DB[a,l]P). PAH metabolites were found to be more potent than parent compounds in producing immunosuppression and inducing p53 expression. Interestingly, DB[a,l]P, a potent carcinogenic PAH not previously characterized for immunotoxicity, was also found to be strongly immunosuppressive. Arsenite (NaAsO(2), As(3)(+)) was found to produce immunosuppression at concentrations as low as 0.5 microM and was immunosuppressive at a 10-fold lower concentration than sodium arsenate (Na(2)HAsO(4), As(5)(+)). Coexposure of spleen cell cultures to PAHs and As(3)(+), both at individual low-effect concentrations, was found to produce profound suppression of the TDAR demonstrating synergy between these two chemical classes of agents.",
Arsenic,1245796,"Promoting effects of dimethylarsinic acid on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced urinary bladder carcinogenesis in rats Abstract: Arsenicals are epidemiologically significant chemicals in relation to induction of urinary bladder cancer in man. In the present study, we investigated the dose-dependent promotion potential of dimethylarsinic acid (DMA), a major metabolite of inorganic arsenicals in mammals, for rat urinary bladder carcinogenesis. In experiment 1, 6-week-old male F344 rats were treated with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 4 weeks and then given one of several concentrations of DMA in their drinking water (groups 1-6: 0, 2, 10, 25, 50 and 100 p.p.m.) for 32 weeks. The development of preneoplastic lesions and tumors (papillomas and carcinomas) in the urinary bladder was enhanced by treatment with DMA in a dose-dependent manner. A significant increase in multiplicity of tumors (papillomas and carcinomas) was observed even at a low concentration of DMA (10 p.p.m.). On the other hand, no preneoplastic lesions and tumors were observed in the rats treated with DMA alone. In experiment 2, different concentrations of DMA (groups 1-4: 0, 10, 25 and 100 p.p.m.) in drinking water were administered to the rats for 8 weeks without prior initiation by BBN. A significant increase in the 5-bromo-2'-deoxyuridine labeling index and alteration of the surfaces of the urinary bladder epithelial cells, as revealed by scanning electron microscopy, provided evidence of a dose-dependent increase in cell proliferation due to the DMA treatment. These results suggest that DMA has the potential to promote rat urinary bladder carcinogenesis and one of the mechanisms involved is its stimulation of cell proliferation in the urinary bladder epithelium.",
Arsenic,1070636,"Fission yeast HMT1 lowers seed cadmium through phytochelatin-dependent vacuolar sequestration in Arabidopsis Abstract: Much of our dietary uptake of heavy metals is through the consumption of plants. A long-sought strategy to reduce chronic exposure to heavy metals is to develop plant varieties with reduced accumulation in edible tissues. Here, we describe that the fission yeast (Schizosaccharomyces pombe) phytochelatin (PC)-cadmium (Cd) transporter SpHMT1 produced in Arabidopsis (Arabidopsis thaliana) was localized to tonoplast, and enhanced tolerance to and accumulation of Cd2+, copper, arsenic, and zinc. The action of SpHMT1 requires PC substrates, and failed to confer Cd2+ tolerance and accumulation when glutathione and PC synthesis was blocked by L-buthionine sulfoximine, or only PC synthesis is blocked in the cad1-3 mutant, which is deficient in PC synthase. SpHMT1 expression enhanced vacuolar Cd2+ accumulation in wild-type Columbia-0, but not in cad1-3, where only approximately 35% of the Cd2+ in protoplasts was localized in vacuoles, in contrast to the near 100% found in wild-type vacuoles and approximately 25% in those of cad2-1 that synthesizes very low amounts of glutathione and PCs. Interestingly, constitutive SpHMT1 expression delayed root-to-shoot metal transport, and root-targeted expression confirmed that roots can serve as a sink to reduce metal contents in shoots and seeds. These findings suggest that SpHMT1 function requires PCs in Arabidopsis, and it is feasible to promote food safety by engineering plants using SpHMT1 to decrease metal accumulation in edible tissues.",
Arsenic,1360202,EFFECT OF SOME SULFUR AMINO-ACIDS SELENIUM AND ARSENIC ON MERCURY TOXICITY USING JAPANESE QUAIL Abstract: HEEP COPYRIGHT: BIOL ABS.,
Arsenic,2337288,"Temporal trends in sleep apnea surgery: 1993-2010 Abstract: <strong>OBJECTIVES/HYPOTHESIS: </strong>Growing evidence supports the use of multilevel surgery to effectively address obstructive sleep apnea (OSA). We sought to characterize changes in the patterns of surgical sleep care over time.<br /><br /><strong>STUDY DESIGN: </strong>Repeated cross-sectional study.<br /><br /><strong>METHODS: </strong>Discharge data from the US Nationwide Inpatient Sample for 232,470 patients who underwent nasal, palatal, or hypopharyngeal procedures for sleep disordered breathing or OSA from 1993 to 2010 were analyzed using cross-tabulations and multivariate regression modeling.<br /><br /><strong>RESULTS: </strong>Inpatient sleep surgical procedures increased from 97,363 performed in 1993-2000 to 135,107 in 2001-2010. Sleep surgery in 2001-2010 was associated with increased hypopharyngeal surgery (relative risk ratio [RRR]?=?3.6, 95% confidence interval [CI]?=?2.6-4.9, P?&lt;?.001), tongue radiofrequency/midline glossectomy (RRR?=?5.1, 95% CI?=?3.4-7.5, P?&lt;?.001), hyoid suspension (RRR?=?6.8, 95% CI?=?3.8-12.5, P?&lt;?.001), nasal surgery (RRR?=?1.3, 95% CI?=?1.1-1.5, P?=?0.002), and multilevel surgery (RRR?=?5.6, 95% CI?=?3.8-9.4, P?&lt;?.001) and decreased tracheostomy (RRR?=?0.58, 95% CI?=?0.49-0.68, P?&lt;?.001) compared to 1993-2000. Patients undergoing sleep surgery in 2001-2010 were more likely to have an OSA diagnosis (RRR?=?1.9, 95% CI?=?1.4-2.5, P?&lt;?.001), obesity (RRR?=?1.5, 95% CI?=?1.4-1.7, P?&lt;?.001), and advanced comorbidity (RRR?=?2.4, 95% CI?=?2.0-2.8, P?&lt;?.001). In 2001-2010, surgeons (&gt;23 cases/yr) in the top-volume quintile were more likely to perform hypopharyngeal procedures (RRR?=?2.4, 95% CI?=?1.7-3.4, P?&lt;?.001,) and to be associated with teaching hospitals (RRR?=?1.5, 95% CI?=?1.0-2.2, P?=?0.034) and less likely to perform tracheostomy (RRR?=?0.27, 95% CI?=?0.18-0.40, P?&lt;?.001). However, they represented only 17% of surgeons performing sleep surgery in contrast to surgeons in the bottom-volume quintile, who performed 35% of cases.<br /><br /><strong>CONCLUSIONS: </strong>These data reflect changing trends in the surgical management of OSA, with meaningful differences in the type of surgical care provided by high-volume surgeons and a significant increase in surgical sleep procedures, particularly nasal and hypopharyngeal surgery.<br /><br /><strong>LEVEL OF EVIDENCE: </strong>2c Laryngoscope, 124:1251-1258, 2014.",
Arsenic,1025317,"Mutual interaction between nutritional status and chronic arsenic toxicity due to groundwater contamination in an area of Terai, lowland Nepal Abstract: <strong>OBJECTIVE: </strong>To reveal the inter-relationship between nutritional status and arsenic toxicity.<br /><br /><strong>DESIGN: </strong>Cross-sectional study.<br /><br /><strong>SETTING: </strong>A survey in an area of lowland Nepal, where a high prevalence of both skin manifestation and malnutrition was observed. Daily arsenic intake was estimated by measuring the arsenic concentration and daily consumption of the drinking water.<br /><br /><strong>PARTICIPANTS: </strong>Adult villagers (248 men and 291 women). About half were classified as &quot;underweight&quot; (body mass index &lt;18.5), indicating poor nutritional status.<br /><br /><strong>MAIN RESULTS: </strong>Arsenic intake was negatively correlated with body mass index and substantially increased the prevalence of underweight individuals, among whom the prevalence of skin manifestations was 1.65-fold higher than normal weight individuals. When exposure level was considered, the prevalence of skin symptoms was consistently higher in the underweight than in the normal group. Although enhanced susceptibility in men was apparent by the increased prevalence of cutaneous symptoms, no sex difference was observed in the prevalence of underweight individuals related with exposure to arsenic.<br /><br /><strong>CONCLUSIONS: </strong>The present data suggested that exposure to arsenic is associated with an increased prevalence of underweight, a serious health problem in developing countries, which in turn is associated with increased skin manifestation of arsenic poisoning.",
Arsenic,1936057,"Road traffic injury mortality and its mechanisms in India: Nationally representative mortality survey of 1.1 million homes Abstract: Objectives To quantify and describe the mechanism of road traffic injury (RTI) deaths in India. Design We conducted a nationally representative mortality survey where at least two physicians coded each non-medical field staff's verbal autopsy reports. RTI mechanism data were extracted from the narrative section of these reports. Setting 1.1 million homes in India. Participants Over 122?000 deaths at all ages from 2001 to 2003. Primary and secondary outcome measures Age-specific and sex-specific mortality rates, place and timing of death, modes of transportation and injuries sustained. Results The 2299 RTI deaths in the survey correspond to an estimated 183?600 RTI deaths or about 2% of all deaths in 2005 nationally, of which 65% occurred in men between the ages 15 and 59?years. The age-adjusted mortality rate was greater in men than in women, in urban than in rural areas, and was notably higher than that estimated from the national police records. Pedestrians (68?000), motorcyclists (36?000) and other vulnerable road users (20?000) constituted 68% of RTI deaths (124?000) nationally. Among the study sample, the majority of all RTI deaths occurred at the scene of collision (1005/1733, 58%), within minutes of collision (883/1596, 55%), and/or involved a head injury (691/1124, 62%). Compared to non-pedestrian RTI deaths, about 55?000 (81%) of pedestrian deaths were associated with less education and living in poorer neighbourhoods. Conclusions In India, RTIs cause a substantial number of deaths, particularly among pedestrians and other vulnerable road users. Interventions to prevent collisions and reduce injuries might address over half of the RTI deaths. Improved prehospital transport and hospital trauma care might address just over a third of the RTI deaths.",
Arsenic,1509347,The assessment of environmental pollution caused by mining and metallurgy wastes from highly polluted post-industrial regions in Southern Poland Abstract: ,
Arsenic,2337087,"Land use and water quality in a rural cloud forest region (Intag, Ecuador) Abstract: The Intag cloud forest region of northwestern Ecuador is characterized by exceptional biodiversity, large known and unknown deposits of copper and other valuable minerals, and a high level of environmental awareness and concern among the human population. Its 1000km of rivers and streams are essential for household use, crop irrigation, livestock production and sustaining unique ecosystems. However, no published data exist on water quality in the region. This study characterizes water quality in five river systems in Intag and relates it to land use (protected forest, agriculture/pasture, urban development or mining) upstream of the sampling point. Additionally, we sampled 15 community water supply systems. Parameters measured included turbidity, temperature, dissolved oxygen, pH, faecal indicator bacteria (FIB), nitrate, phosphate, ammonium, Ni, Mn, Cu, Zn, Cd, Pb, As, Cr, discharge and aquatic invertebrate diversity. Significant differences in pH, aquatic invertebrate diversity, and the concentrations of FIB, nutrients and dissolved metals were observed between land use groups. Forested streams consistently had the lowest pollutant concentrations, whereas those flowing past population centres or mining areas showed the greatest impairment. Elevated As concentrations were observed in association with abandoned mining boreholes, hot springs and wastewater discharges. FIB, nutrient and metal concentrations in water systems were similar to those in forested streams, indicating that these systems maintain water in an unpolluted condition. To preserve and enhance Intag's generally good water quality, we recommend installing wastewater treatment systems in larger towns and approaching all mining activity, including exploration, with extreme caution.",
Arsenic,1579354,"Two novel calixarene functionalized iron oxide magnetite nanoparticles as a platform for magnetic separation in the liquid-liquid/solid-liquid extraction of oxyanions Abstract: This article focuses on the syntheses of 25,27-bis[3-(N-ethylsulfonic acid)aminopropxy]-26,28-dihydroxy-5,11,17,23-tetra-tert-butyl-calix[4]arene (3) and 25,27-bis[3-(N-ethyl-dihydrogen phosphate)aminopropxy]-26,28-dihydroxy-5,11,17,23-tetra-tert-butyl-calix[4]arene (4) as well as their immobilization onto [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-modified Fe3O4 magnetite nanoparticles, and the extraction abilities of four new extractants which were characterized by a combination of FTIR, (1)H NMR, elemental analyses, transmission electron microscopy (TEM) and thermogravimetric analyses (TGA) involving electrostatic and hydrogen bonding interactions between the calixarene and oxide anions such as arsenate and dichromate anions. The extraction results indicate that these new calixarene derivatives having high extraction capabilities would be used as effective extractants for the removal of the dichromate/arsenate ions from water.",
Arsenic,446844,"Evaluation of arsenic, cobalt, copper and manganese in biological samples of steel mill workers by electrothermal atomic absorption spectrometry Abstract: The determination of trace and toxic elements in biological samples (blood, urine and scalp hair samples) of human beings is an important clinical test. The aim of our present study was to determine the concentration of arsenic (As), copper (Cu), cobalt (Co) and manganese (Mn), in biological samples of male production workers (PW) and quality control workers (QW) of steel mill, with aged 25-55 years, to assess the possible influence of environmental exposure. For comparison purpose, the same biological samples of unexposed healthy mates of same age group were collected as control subjects. The determination of all elements in biological samples was carried out by electrothermal atomic absorption spectrometry, prior to microwave assisted acid digestion. The accuracy of the As, Cu, Co and Mn measurements was tested by simultaneously analyzing certified reference materials (CRMs) and for comparative purposes conventional wet acid digestion method was used on the same CRMs. No significant differences were observed between the analytical results and the certified values, using both methods (paired t-test at P > 0.05). The results indicate that concentrations of As, Cu, Co and Mn in all three biological samples of the exposed workers (QW and PW) were significantly higher than those of the controls. The possible correlation of these elements with the etiology of different physiological disorders is discussed. The results were also demonstrated the need of attention for improvements in workplace, ventilation and industrial hygiene practices. Toxicology and Industrial Health 2009; 25: 59-69.",
Arsenic,2088427,"Groundwater Quality of Turkmen Mountain, Turkey Abstract: ",
Arsenic,621615,"Health Effects of Early Life Exposure to Arsenic Abstract: Inorganic arsenic is a potent human carcinogen and general toxicant. More than one hundred million people are exposed to elevated concentrations, mainly via drinking water, but also via industrial emissions. Arsenic is metabolized via methylation and reduction reactions, methylarsonic acid and dimethylarsinic acid being the main metabolites excreted in urine. Both inorganic arsenic and its methylated metabolites easily pass the placenta and both experimental and human studies have shown increased risk of impaired foetal growth and increased foetal loss. Recent studies indicate that prenatal arsenic exposure also increases the risk of adverse effects during early childhood. There is a growing body of evidence that the intrauterine or early childhood exposure to arsenic also induces changes that will become apparent much later in life. One epidemiological study indicated that exposure to arsenic in drinking water during early childhood or in utero was associated with an increased mortality in young adults from both malignant and non-malignant lung disease. Furthermore, a series of experimental animal studies provide strong support for late effects of arsenic, including various forms of cancer, following intrauterine arsenic exposure. The involved modes of action include epigenetic effects, mainly via DNA hypomethylation, endocrine effects (most classes of steroid hormones), immune suppression, neurotoxicity, and interaction with enzymes critical for foetal development and programming. [ABSTRACT FROM AUTHOR] Copyright of Basic & Clinical Pharmacology & Toxicology is the property of Blackwell Publishing Limited and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,710996,"New insights into the mechanism of arsenite methylation with the recombinant human arsenic (+3) methyltransferase (hAS3MT) Abstract: The catalytic mechanism of the recombinant human arsenic (+3) methyltransferase (hAS3MT) was studied using kinetics, initial velocity and spectroscopy. The production and the distribution of methylated arsenicals changed with various concentrations of arsenite/S-adenosyl-L-methionine (SAM)/thiols, enzyme contents, and incubation times. These results suggest a sequential methylation of arsenite to monomethylated arsenicals (MMA) and dimethylated arsenicals (DMA). In addition, competition exists between the two reactions. hAS3MT showed the greatest activity at pH 8.5 with glutathione (GSH) as the reductant. This might indicate that a balance between the deprotonation and protonation of sulfhydryl groups is required. Initial velocity studies illuminate an ordered sequence for the binding of SAM and arsenite to the hAS3MT; while GSH should probably be placed either as the first reactant or as a reactant combining with the enzyme only after products have been released. The interactions between substrate/cofactors and the hAS3MT were first monitored by UV-visible and circular dichroism spectroscopy. It revealed that arsenite and SAM combined with the hAS3MT before reaction started; whereas, no interactions between GSH and the hAS3MT were detected. Integrating the results from kinetics, initial velocity and spectroscopy studies, an ordered mechanism are originally attained, with the SAM as the first reactant that adds to the hAS3MT and arsenite as the second one. Arsenite is successively methylated reductively, rather than a stepwise oxidative methylation. GSH should combine with the hAS3MT after the methylation to reduce the disulfide bond formed during the catalytic cycle in the hAS3MT to resume the active form of the enzyme.",
Arsenic,610697,"Effects of endogenous hydrogen peroxide and glutathione on the stability of arsenic metabolites in rat bile Abstract: Abstract: Trivalent arsenicals such as arsenite (iAs<sup>III</sup>), monomethylarsonous acid (MMA<sup>III</sup>) and dimethylarsinous acid (DMA<sup>III</sup>) are more toxic than analogous pentavalent compounds such as arsenate (iAs<sup>V</sup>), monomethylarsonic acid (MMA<sup>V</sup>) and dimethylarsinic acid (DMA<sup>V</sup>). It has been reported that arsenicÃ¢â‚¬â€œglutathione (As-GSH) complexes such as arsenic triglutathione (ATG) and methylarsenic diglutathione (MADG) are major metabolites in rat bile following intravenous administration of iAs<sup>III</sup>. Recently, we have shown that both ATG and MADG are unstable and easily hydrolyzed to iAs<sup>III</sup> and MMA<sup>III</sup>, respectively, and that MMA<sup>III</sup> is oxidized to MMA<sup>V</sup> in bile. In the present study we report the effects of H2O2 and GSH on the stability of As-GSH complexes in rat bile. Male SD rats were injected intravenously with saline or iAs<sup>III</sup> at a dose of 0.2 or 2.0Ã‚Â mg As/kg body weight, and bile fluid was collected on ice for 30Ã‚Â min. To estimate the stability of As-GSH complexes in bile, ATG or MADG was added to untreated, heat-treated, catalase-treated, or dialyzed bile, and then incubated at 37Ã‚Â Ã‚Â°C for 10Ã‚Â min. Concentrations of biliary H2O2 and GSH in the higher dose group were 12.6- and 4.5-times higher than the control value, respectively. Exogenously added trivalent arsenicals were oxidized to pentavalent arsenicals in the bile depending on the biliary concentration of H2O2. Both catalase and dialysis prevented oxidation of trivalent arsenicals to the corresponding pentavalent compounds. Exogenously added GSH stabilized As-GSH complexes in bile. These results suggest that H2O2 converts trivalent arsenicals to less toxic pentavalent arsenicals, whereas GSH prevents hydrolysis of As-GSH complexes and the generation of unconjugated toxic ... [Copyright 2008 Elsevier] Copyright of Toxicology & Applied Pharmacology is the property of Academic Press Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,2337113,"A review on completing arsenic biogeochemical cycle: Microbial volatilization of arsines in environment Abstract: Arsenic (As) is ubiquitous in the environment in the carcinogenic inorganic forms, posing risks to human health in many parts of the world. Many microorganisms have evolved a series of mechanisms to cope with inorganic arsenic in their growth media such as transforming As compounds into volatile derivatives. Bio-volatilization of As has been suggested to play an important role in global As biogeochemical cycling, and can also be explored as a potential method for arsenic bioremediation. This review aims to provide an overview of the quality and quantity of As volatilization by fungi, bacteria, microalga and protozoans. Arsenic bio-volatilization is influenced by both biotic and abiotic factors that can be manipulated/elucidated for the purpose of As bioremediation. Since As bio-volatilization is a resurgent topic for both biogeochemistry and environmental health, our review serves as a concept paper for future research directions.",
Arsenic,2279541,"Long-term low-dose exposure of human urothelial cells to sodium arsenite activates lipocalin-2 via promoter hypomethylation Abstract: We previously reported that the sustained exposure of human urothelial cells (HUCs) to low-dose sodium arsenite induces changes in the gene expression profile and neoplastic transformation. In this study, we used the HumanMethylation27 BeadChip to analyze genome-wide methylation profiles and 5-aza-2'-deoxycytidine to examine the involvement of promoter methylation in gene expression. Because the expression of lipocalin-2 (LCN2) was highly enhanced by promoter hypomethylation in inorganic arsenic (iAs)-HUCs cells as well as bladder cancer tissues, we further showed that mutations at the binding sequences for NF-?B and C/EBP-? significantly reduced LCN2 promoter activity. By chromatin immunoprecipitation assay, we demonstrated the significantly increased binding of RelA (p65) and NF-?B1 (p50) to the hypomethylated promoter of LCN2 in the iAs-HUCs. Furthermore, we also demonstrated that LCN2 overexpression was crucial for the neoplastic characteristics of the iAs-HUCs, such as enhanced anchorage-independent growth, resistance to serum deprivation and activation of NF-?B signaling. In addition, our results indicated that enhanced NF-?B activity in iAs-HUCs was via LCN2-mediated increase in intracellular iron and reactive oxygen species levels. Taken together, our results show that sustained low-dose arsenic exposure results in epigenetic changes and enhanced oncogenic potential via LCN2 overexpression.",
Arsenic,1342969,"Study of chemical forms of heavy metals collected from the sediments of tin mining catchment Abstract: The chemical speciation of heavy metals (arsenic, chromium, copper, lead, zinc and tin) in the sediments of the former tin mining catchment Bestari Jaya, Peninsular Malaysia was determined using the latest version of the Community Bureau of Reference, the BCR 3-step, sequential extraction procedure. A fourth step was introduced for the digestion and analysis of the residue. The analysis of total metal content was carried out using microwave-assisted acid digestion. The percentage of each metal obtained from the four steps extraction (acid-soluble + reducible + oxidisable + residual) is in good agreement with the percentage of total metal content obtained from microwave digestion, which implies that the accuracy of the procedure. The degree of pollution in catchment sediments was assessed using geoaccumulation index Igeo and pollution intensity I-POLL. The results indicates that: (1) the sediments have been polluted with arsenic (8.8%), chromium (12.9%), copper (17.4%), lead (19.5%), zinc (14.9%) and tin (33.8%) and have high anthropogenic influences; (2) the calculation of geo-accumulation index suggests that catchment sediments have background concentrations of all the studied metals (Igeo &lt; 0); (3) high I-POLL showed that all of these heavy metals pose a high environmental risk; and (4) the mobility order of metals in sediments at S1 and S2 was Sn&gt;Pb&gt;Zn&gt;Cr&gt;Cu&gt;As, whereas at S3, S4 and S5 it was Cu&gt;Pb&gt;Zn&gt;Cr&gt;Sn&gt;As. In conclusion, acidic pH, total organic carbon, scavenging ability and co-precipitation (inclusion, occlusion and adsorption) of studied metals with nonmetals could account for changes in the geochemistry of the catchment sediments.",
Arsenic,1350546,"Trace metals in marine foodstuff: Bioavailability estimation and effect of major food constituents Abstract: A simulated in vitro digestion method for the dialyzability assessment of trace metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, V and Zn) from different seafood and edible seaweed has been developed. Inductively coupled plasma-mass spectrometry was used for metal determination in the dialyzates and in the samples after a microwave assisted acid digestion pre-treatment. Trueness of the procedure for total metal determination has been assessed by analyzing different certified reference materials (DORM-2, BCR 279 and NIES-09); whereas, trueness for the in vitro bioavailability method has been established after performing a mass balance study. Low (2.6–10.8%) and moderate (21.5–41.3%) dialyzability percentages have been found in seafood samples. However, high dialyzability percentages (30.0–74.7%) have been found in edible seaweeds. Linear and quadratic models have shown that the bioavailability of some metals exhibited good positive correlation with the carbohydrate content and also with the dietary fibre level. Protein content showed good negative correlation with the bioavailability of certain metals, whereas, moderate negative correlation was found with fat content.",
Arsenic,1017684,"NanoSIMS analysis of arsenic and selenium in cereal grain Abstract: *Cereals are an important source of selenium (Se) to humans and many people have inadequate intakes of this essential trace element. Conversely, arsenic (As) is toxic and may accumulate in rice grain at levels that pose a health risk. Knowledge of the localization of selenium and arsenic within the cereal grain will aid understanding of their deposition patterns and the impact of processes such as milling. *High-resolution secondary ion mass spectrometry (NanoSIMS) was used to determine the localization of Se in wheat (Triticum aestivum) and As in rice (Oryza sativa). Combined synchrotron X-ray fluorescence (S-XRF) and NanoSIMS analysis utilized the strengths of both techniques. *Selenium was concentrated in the protein surrounding the starch granules in the starchy endosperm cells and more homogeneously distributed in the aleurone cells but with Se-rich hotspots. Arsenic was concentrated in the subaleurone endosperm cells in association with the protein matrix rather than in the aleurone cells. NanoSIMS indicated that the high intensity of As identified in the S-XRF image was localized in micron-sized hotspots near the ovular vascular trace and nucellar projection. *This is the first study showing subcellular localization in grain samples containing parts per million concentrations of Se and As. There is good quantitative agreement between NanoSIMS and S-XRF.",
Arsenic,1021461,"Hypertension incidence after tap-water implementation: A 13-year follow-up study in the arseniasis-endemic area of southwestern Taiwan Abstract: Hypertension is the leading cause of cardiovascular disease worldwide. Long-term arsenic exposure has been linked to increased risk for hypertension; however, little is known whether a previous exposure has lingering effects on hypertension after the exposure being reduced significantly for decades. The study cohort was established in 1990 in an arseniasis-endemic area of 3 villages - Homei, Fuhsin, and Hsinming in Putai Township located on the southwestern coast of Taiwan, where residents were exposed to artesian well water (median level=700 to 930 ?g/L) until early 1970s. The original cohort consisted of 490 non-hypertensive residents over 30-yrs-old and 352 of them were successfully followed up in 2002/03. Arsenic concentrations in the artesian well water consumed by residents during 1960s were used to indicate the previous exposure while urinary arsenic species measured in 2002/3 was used to represent current exposure. Hypertension incidences were 27.4, 65.6, and 69.1, per 1000 person-years for men aged 35-49, 50-64, and 65-74 years, respectively being higher than the corresponding rates of 25.1, 46.1, and 57.2 in a community-based longitudinal study. Cancer was the major cause of the total deaths (17/30=57%). Diastolic blood pressure was shown to increase with an increased cumulative arsenic ingestion from drinking water (?=0.27, p&lt;0.001). The incidence was increased by 2.43-fold in subjects of As(V)?2.67 ?g/g creatinine as compared to those of As(V)&lt;1.20 ?g/g creatinine (the third vs. first tertile; p=0.047) after adjustment for conventional risk factors. This study suggests that three decades after cessation of drinking artesian well water, residents of the endemic area are still at increased risk for developing hypertension, particularly those who excrete high amounts of As(V).",
Arsenic,627442,"Variability in human metabolism of arsenic Abstract: Estimating the nature and extent of human cancer risks due to arsenic (As) in drinking water is currently of great concern, since millions of persons worldwide are exposed to arsenic, primarily through natural enrichment of drinking water drawn from deep wells. Humans metabolize and eliminate As through oxidative methylation and subsequent urinary excretion. While there is debate as to the role of methylation in activation/detoxification, variations in arsenic metabolism may affect individual risks of toxicity and carcinogenesis. Using data from three populations, from Mexico, China, and Chile, we have analyzed the distribution in urine of total arsenic and arsenic species (inorganic arsenic (InAs), monomethyl arsenic (MMA), and dimethyl arsenic (DMA). Data were analyzed in terms of the concentration of each species and by evaluating MMA:DMA and (MMA+DMA):InAs ratios. In all persons most urinary As was present as DMA. Male:female differences were discernible in both high- and low-exposure groups from all three populations, but the gender differences varied by populations. The data also indicated bimodal distributions in the ratios of DMA to InAs and to MMA. While the gene or genes responsible for arsenic methylation are still unknown, the results of our studies among the ethnic groups in this study are consistent with the presence of functional genetic polymorphisms in arsenic methylation leading to measurable differences in toxicity. This analysis highlights the need for continuing research on the health effects of As in humans using molecular epidemiologic methods.",
Arsenic,627599,"Assessment of DNA damage in peripheral blood lymphocytes of individuals susceptible to arsenic induced toxicity in West Bengal, India Abstract: Assessment of DNA damage was carried out using alkaline comet assay in lymphocytes of 30 individuals exposed to high levels of arsenic (247.12+/-18.93 microg/l) through contaminated groundwater in North 24 Parganas district, West Bengal, India. All of them exhibited high arsenic contents in nail (4.20+/-0.67 microg/g), hair (2.06+/-0.20 microg/g) and urine (259.75+/-33.89 microg/l) samples and manifested various arsenical skin lesions. Unexposed samples were collected from 30 residents of the unaffected East Midnapur district with very little or no exposure to arsenic (7.69+/-0.49 microg/l) in drinking water. The results were evaluated principally by manual analysis of comets and partly by computerized image analysis. Both the analytical methods exhibited a high degree of agreement in results. The exposed participants expressed significantly higher DNA damage (p < 0.01) in their lymphocytes than the unexposed participants. Alkaline comet assay was also combined with formamidopyrimidine-DNA glycosylase enzyme digestion to confirm that arsenic induced oxidative base damage in the lymphocytes. Significant positive trend effects of comet lengths in relation to arsenic levels in water prove that DNA damage can be used as a sensitive biomarker of arsenic exposure. This study demonstrates that arsenic induced significant DNA damage in the exposed participants, which could correspond to a higher susceptibility to arsenic induced toxicity and carcinogenicity.",
Arsenic,1579288,"Biosorption of heavy metals by lactic acid bacteria and identification of mercury binding protein Abstract: Heavy metals cause various health hazards. Using lactic acid bacteria (LAB), we tested the biosorption of heavy metals e.g. cadmium (Cd) (II), lead (Pb) (II), arsenic (As) (III), and mercury (Hg) (II). Cd (II) sorption was tested in 103 strains using atomic absorption spectrophotometery (AAS). Weissella viridescens MYU 205 (1×10(8) cells/ml) decreased Cd (II) levels in citrate buffer (pH 6.0) from one ppm to 0.459 ± 0.016 ppm, corresponding to 10.46 ?g of Cd (II). After screening, 11 LAB strains were tested using various pH (pH 4.0, 5.0, 6.0, 7.0) showing the sorption was acid sensitive; and was cell concentration dependent, where the Cd (II) concentration decreased from one ppm to 0.042 (max) / 0.255 (min) ppm at 1×10(10) cells/ml. Additionally, the biosorption of Pb (II), As (III), and Hg (II) were tested using an inductively coupled plasma mass spectrometer (ICP-MS). The Hg (II) concentration was reduced the most followed by Pb (II) and As (III). Many of the bacterial cell surface proteins of W. viridescens MYU 205 showed binding to Hg (II) using the Hg (II) column assay. Having a CXXC motif, a ?14 kDa protein may be one of the Hg (II) binding proteins. LAB biosorption may aid the detoxification of people exposed to heavy metals.",
Arsenic,1337321,"A greenhouse and field-based study to determine the accumulation of arsenic in common homegrown vegetables grown in mining-affected soils Abstract: The uptake of arsenic by plants from contaminated soils presents a health hazard that may affect home gardeners neighboring contaminated environments. A controlled greenhouse study was conducted in parallel with a co-created citizen science program (home garden experiment) to characterize the uptake of arsenic by common homegrown vegetables near the Iron King Mine and Humboldt Smelter Superfund site in southern Arizona. The greenhouse and home garden arsenic soil concentrations varied considerably, ranging from 2.35 to 533mgkg(-1). In the greenhouse experiment four vegetables were grown in three different soil treatments and in the home garden experiment a total of 63 home garden produce samples were obtained from 19 properties neighboring the site. All vegetables accumulated arsenic in both the greenhouse and home garden experiments, ranging from 0.01 to 23.0mgkg(-1) dry weight. Bioconcentration factors were determined and show that arsenic uptake decreased in the order: Asteraceae&gt;Brassicaceae&gt;Amaranthaceae&gt;Cucurbitaceae&gt;Liliaceae&gt;Solanaceae&gt;Fabaceae. Certain members of the Asteraceae and Brassicaceae plant families have been previously identified as hyperaccumulator plants, and it can be inferred that members of these families have genetic and physiological capacity to accumulate, translocate, and resist high amounts of metals. Additionally, a significant linear correlation was observed between the amount of arsenic that accumulated in the edible portion of the plant and the arsenic soil concentration for the Asteraceae, Brassicaceae, Amaranthaceae, and Fabaceae families. The results suggest that home gardeners neighboring mining operations or mine tailings with elevated arsenic levels should be made aware that arsenic can accumulate considerably in certain vegetables, and in particular, it is recommended that gardeners limit consumption of vegetables from the Asteraceae and Brassicaceae plant families.",
Arsenic,1017966,"Serum proteomic profiling analysis of chronic arsenic exposure by using SELDI-TOF-MS technology Abstract: This study was to investigate the differences in serum proteomic profiling among subjects exposed to different levels of arsenic in drinking water and to identify proteins related to arsenicosis. A total of 148 subjects from endemic regions of China were selected and divided into low (0-8.30 microg/L), medium (16.30-37.60 microg/L) and high (140.88-273.67 microg/L) exposure groups. High exposure group consisted of subjects with and without skin lesions. Serum proteomic profiling was analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) technology. Twenty proteins were found significantly different among three groups. Further multivariate logistic regression revealed that no different proteins existed in medium versus low exposure group. A panel of five proteins, including m/z of 15167.7, 7783.1, 7580.7, 2952.6 and 2237.4, was seen in high versus low exposure group, with a sensitivity of 93.0% and specificity of 87.5%. The same panel was found in high versus a combination of low and medium exposure groups but with somewhat lower predicting power. Only one protein was significantly different between high exposure group with and without skin lesions. The results indicate that high levels of arsenic exposure could significantly change human serum proteomic profiling, which can be detected before skin lesions occur.",
Arsenic,710925,"Folate deficiency, hyperhomocysteinemia, low urinary creatinine, and hypomethylation of leukocyte DNA are risk factors for arsenic-induced skin lesions Abstract: Arsenic methylation relies on folate-dependent one-carbon metabolism and facilitates urinary As elimination. Clinical manifestations of As toxicity vary considerably among individuals and populations, and poor methylation capacity is thought to confer greater susceptibility. After determining that folate deficiency, hyperhomocysteinemia, and low urinary creatinine are associated with reduced As methylation, and that As exposure is associated with increased genomic methylation of leukocyte DNA, we asked whether these factors are associated with As-induced skin lesion risk among Bangladeshi adults. We conducted a nested case-control study of 274 cases who developed lesions 2 years after recruitment, and 274 controls matched to cases for sex, age, and water As. The odds ratios and 95% confidence intervals (CIs) for development of skin lesions for participants who had low folate (< 9 nmol/L), hyperhomocysteinemia (men, > 11.4 micromol/L; women, > 10.4 micromol/L), or hypomethylated leukocyte DNA at recruitment (< median) were 1.8 (95% CI, 1.1-2.9), 1.7 (95% CI, 1.1-2.6), and 1.8 (95% CI, 1.2-2.8), respectively. Compared with the subjects in the first quartile, those in the third and fourth quartiles for urinary creatinine had a 0.4-fold decrease in the odds of skin lesions (p < 0.01). These results suggest that folate deficiency, hyperhomocysteinemia, and low urinary creatinine, each associated with decreased As methylation, are risk factors for As-induced skin lesions. The increased DNA methylation associated with As exposure previously observed, and confirmed among controls in this study, may be an adaptive change because hypomethylation of leukocyte DNA is associated with increased risk for skin lesions.",1
Arsenic,1345678,"Single and combination toxic metal exposures induce apoptosis in cultured murine podocytes exclusively via the extrinsic caspase 8 pathway Abstract: Arsenite, cadmium, and mercury are among the most abundant toxic metals (TM) in the environment. Although the most common renal manifestation of TM toxicity is proximal tubular dysfunction, significant glomerular injury can also occur. We hypothesized that glomerular injury following TM exposure results from TM-induced apoptosis of podocytes. To test this hypothesis we examined the extent of apoptosis and the apoptotic pathways induced in cultured murine podocytes incubated for three days with arsenite, cadmium, or mercury, and with equimolar combinations of all three metals. Apoptosis was detected by DNA laddering, and the number of apoptotic nuclei determined by Tunel assay. Treatment for three days with each TM resulted in DNA laddering and induced a dose-dependent increase in apoptotic nuclei. In contrast, treatment with equimolar combinations of TM induced significantly fewer apoptotic nuclei than individual TM treatments. Apoptosis induced by each TM was associated with a significant (approximately 400%) increase in caspase 8 activity, but no change in caspase 9 activity, and Western analyses revealed a marked up-regulation of Fas (approximately 500%) and FADD (approximately 300%) with no change in expression of Bax, Bcl-2, or Bcl-xL. Similar to the apoptotic response, combinations of TM induced less caspase 8 activity and Fas/FADD expression than individual TM treatments. Collectively, these results demonstrate that (1) TM induced apoptosis in cultured murine podocytes via the extrinsic Fas-FADD caspase 8 pathway, rather than the mitochondrial apoptotic pathway, and (2) combination TM exposure induced less apoptosis than individual TM, indicating an antagonistic rather than an additive or synergistic toxicity.",
Arsenic,2337167,"Genome Sequence of the Aerobic Arsenate-Reducing Bacterium Pantoea sp. Strain IMH Abstract: We here report the draft assembly for the genome of Pantoea sp. strain IMH, isolated from arsenic-contaminated soil in Inner Mongolia, China, with the ability to aerobically reduce arsenate to arsenite. The genome sequence will allow for the characterization of the molecular mechanisms of arsenate reduction.",
Arsenic,1519146,"Short and long term gene expression variation and networking in human proximal tubule cells when exposed to cadmium Abstract: Cadmium (Cd²?) is a known nephrotoxin causing tubular necrosis during acute exposure and potentially contributing to renal failure in chronic long-term exposure. To investigate changes in global gene expression elicited by cadmium, an in-vitro exposure system was developed from cultures of human renal epithelial cells derived from cortical tissue obtained from nephrectomies. These cultures exhibit many of the qualities of proximal tubule cells. Using these cells, a study was performed to determine the cadmium-induced global gene expression changes after short-term (1 day, 9, 27, and 45 ?M) and long-term cadmium exposure (13 days, 4.5, 9, and 27 ?M). These studies revealed fundamental differences in the types of genes expressed during each of these time points. The obtained data was further analyzed using regression to identify cadmium toxicity responsive genes. Regression analysis showed 403 genes were induced and 522 genes were repressed by Cd²? within 1 day, and 366 and 517 genes were induced and repressed, respectively, after 13 days. We developed a gene set enrichment analysis method to identify the cadmium induced pathways that are unique in comparison to traditional approaches. The perturbation of global gene expression by various Cd²? concentrations and multiple time points enabled us to study the transcriptional dynamics and gene interaction using a mutual information-based network model. The most prominent network module consisted of INHBA, KIF20A, DNAJA4, AKAP12, ZFAND2A, AKR1B10, SCL7A11, and AKR1C1.",
Arsenic,2337271,"Chronic arsenic poisoning following ayurvedic medication Abstract: Background: Ayurveda, Indian traditional system of medicine, is practiced commonly in South East Asia and in many parts of the world. Many ayurvedic drugs contain heavy metals and may lead to metal toxicity. Of these, chronic lead poisoning is the most common. Chronic arsenic poisoning following the use of ayurvedic medication, though reported, is rare. Case Report: We describe three patients who presented with features of chronic arsenic poisoning following prolonged ayurvedic medication use. The diagnosis of chronic arsenic poisoning was confirmed by high arsenic levels in the blood, urine, hair, and nails in all the three patients and in ayurvedic drug in two patients. The ayurvedic medication was discontinued and treatment with D-penicillamine started. At 6 months after treatment, blood arsenic levels returned to normal with clinical recovery in all of them. Conclusion: Arsenic poisoning following ayurvedic medication is much less common than lead poisoning, though mineral ayurvedic medicines may lead to it. We used D-penicillamine as chelator and all of them recovered. Whether withdrawal of medication alone or D-penicillamine also played a role in recovery is unclear and needs to be assessed.",
Arsenic,1348681,"ACTIVATION OF HEAT-SHOCK TRANSCRIPTION FACTORS BY DELTA-12-PROSTAGLANDIN-J2 AND ITS INHIBITION BY INTRACELLULAR GLUTATHIONE Abstract: We recently showed that delta 12-prostaglandin (PG) J2 bound to the thiol groups of nuclear proteins and stimulated the synthesis of a 67-kDa heat shock protein (HSP) in porcine aortic endothelial cells, and that intracellular glutathione (GSH) blocked this binding and HSP induction (Koizumi et al., Biochem Pharmacol 44: 1597-1602, 1992). In the present study, we examined the molecular mechanism underlying the induction of HSP by delta 12-PGJ2. Treatment of cells with delta 12-PGJ2 induced the activation of heat shock transcription factors (HSF) in a time- and concentration-dependent manner. Cycloheximide pretreatment inhibited this activation. Treatment of cells with buthionine sulfoximine, an inhibitor of GSH synthesis, depleted the intracellular GSH and enhanced the activation of HSF by delta 12-PGJ2, but treatment with GSH increased the intracellular GSH level and thus reduced the activation. Moreover, the thiol-reactive agents arsenite and diethylmaleate also induced the activation of HSF, and this activation was inhibited by GSH treatment and enhanced by buthionine sulfoximine treatment. These results taken together suggest that delta 12-PGJ2 binds to the thiol groups of nuclear proteins and activates HSF, leading to the synthesis of the 67-kDa HSP.",
Arsenic,2279588,"Immobilization of arsenate in a sandy loam soil using starch-stabilized magnetite nanoparticles Abstract: This study investigated effectiveness of starch-stabilized magnetite nanoparticles for in situ enhanced sorption and immobilization of arsenate, As(V), in a model sandy loam soil. Batch tests showed that the nanoparticles offered an As(V) distribution coefficient of 10,000L/g, which is &gt;3 orders of magnitude greater than that for the soil. Batch and column experimental results revealed that the nanoparticle treatment greatly reduced water-leachable As(V) and the leachability of As(V) remaining in the soil per TCLP (Toxicity Characteristic Leaching Procedure) analysis. Column tests showed that water-leachable As(V) from the As(V)-laden soil containing 31.45mg/kg was reduced by ?93% and the TCLP leachability by &gt;83% when the soil was treated with 34 pore volumes of a 0.1g-Fe/L of the nanoparticle suspension. While the nanoparticles are deliverable in the soil, the effective travel distance of the nanoparticles can be manipulated by controlling the injection flow rate. Under natural groundwater flow conditions (velocity ?2.4×10(-4)cm/s), the delivered nanoparticles are confined within a limited distance (&lt;6.1cm).",
Arsenic,1337760,"Digital analysis technique for uncertainty reduction in colorimetric arsenic detection method Abstract: This article proposes an alternative to increase the reliability and reproducibility of a colorimetric method to measure arsenic (As) concentrations. The method of analysis developed incorporates a digital analysis technique to eliminate the operator dependence of results, and As concentrations are quantitatively determined from digital levels computed from photographs of the colorimetric reaction that emerges during the test. This technique allows the sensitivity of the detection to be increased at low concentration ranges, which is of fundamental importance for the detection of As given the current acceptable limit for drinking water. The results obtained show a very good correlation between As concentrations determined by means of analytical laboratory techniques and the method proposed in this research.",
Arsenic,1337765,"Reuse of washing effluent containing oxalic acid by a combined precipitation-acidification process Abstract: This study aims at evaluating the reuse feasibility of effluent produced by the soil washing of mine tailings with oxalic acid. Alkaline chemicals such as NaOH, Ca(OH)(2), and Na(2)CO(3) are used for the precipitation of arsenic and heavy metals in the effluent containing oxalic acid. All of the target contaminants are removed with very high efficiency (up to 100%) at high pH. The precipitation using NaOH at pH 9 is determined to be the most cost-effective method for the removal of arsenic as well as heavy metals in the effluent. The effluent decontaminated by NaOH is consecutively reused for the soil washing of raw mine tailings, resulting in considerable efficiency. Furthermore, even more arsenic and heavy metals are extracted from raw mine tailings by acidifying the decontaminated effluent under the alkaline condition, compared with direct reuse of the decontaminated effluent. Here, the oxalic acid, which is a weak complex-forming ligand as well as a weak acid, has noticeable effects on both soil washing and effluent treatment by precipitation. It extracts efficiently the contaminants from the mine tailings without adverse change of soil and also makes possible the precipitation of the contaminants in the effluent unlike strong chelating reagent. Reuse of the washing effluent containing oxalic acid would make the existing soil washing process more environment-friendly and cost-effective.",
Arsenic,628002,"Animal species difference in the uptake of dimethylarsinous acid (DMA(III)) by red blood cells Abstract: The animal species difference in the metabolism of arsenic was studied from the viewpoint of the mechanism underlying its distribution in the form of dimethylated arsenic in red blood cells (RBCs). Dimethylarsinic (DMA(V)) and dimethylarsinous (DMA(III)) acids were incubated with rat, hamster, mouse, and human RBCs, and the uptake rates and chemical forms of arsenic were determined. Although DMA(V) was practically not or taken up slowly by RBCs of all the present animal species, DMA(III) was taken efficiently in the order of rat > hamster > human, RBCs of mice taking it up less efficiently and with a different pattern from the former three animals. Further, although DMA(III) taken up by rat RBCs was retained, that by hamster ones was effluxed in the form of DMA(V). The uptake of DMA(III) and efflux of DMA(V) took place much more slowly in human RBCs than rat and hamster ones. The uptake of DMA(III) by RBCs was inhibited on the oxidation of glutathione with diamide. Incubation of DMA(III), but not of DMA(V), with a hemolysate produced a high molecular weight complex, which increases in the presence of glutathione, suggesting that DMA(III) taken up by RBCs is retained through the formation of a complex with protein(s) specific to animal species, and effluxed from RBCs after being oxidized to DMA(V). These results indicate that DMA is taken up by RBCs in the form of DMA(III), and that the uptake and efflux rates are dependent on the animal species, the effluxed arsenic being DMA(V). The present results suggest that the uptake of DMA by RBCs is an additional contributing factor to the animal species difference in the metabolism of arsenic in addition to the reduction and methylation capacity in the liver.",
Arsenic,1030186,"Occupational and environmental exposure to arsenic--increased urinary arsenic level in children Abstract: The sum of concentrations of inorganic arsenic, methylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) in urine from adults and children living in an unpolluted area was compared with the corresponding sum measured in urine from adults and children living in an area polluted with arsenic and in urine from persons occupationally exposed to arsenic. The median values for 22 adults and 10 children aged 3-10 years living in the unpolluted area were 9.3 and 19.8 nmol As/mmol creatinine, respectively. The corresponding ranges were 3.2-27.9 and 7.7-57.8 nmol As/mmol creatinine, respectively. The difference between adults and children was tested by Mann-Whitney's non-parametric test and found to be significant (p less than 0.0025). No significant difference was found in arsenic concentration in urine from 73 adults and 10 children living in the polluted area compared with the arsenic concentration in urine from those living in the unpolluted area. The arsenic level in urine from adult workers handling arsenic-treated wood was approximately four-fold higher (p less than 0.001), with a maximum recorded concentration corresponding to 814.9 nmol As/mmol creatinine. The arsenic levels in urine from two glass workers were nine- and two-fold higher, respectively. No significantly increased arsenic levels were found in urine from workers impregnating wood and in urine from lead accumulator workers.",
Arsenic,1015860,"Arsenic species in poultry feather meal Abstract: Organoarsenical drugs are widely used in the production of broiler chickens in the United States. Feathers from these chickens are processed into a meal product that is used as an animal feed additive and as an organic fertilizer. Research conducted to date suggests that arsenical drugs, specifically roxarsone, used in poultry production result in the accumulation of arsenic in the keratinous material of poultry feathers. The use of feather meal product in the human food system and in other settings may result in human exposures to arsenic. Consequently, the presence and nature of arsenic in twelve samples of feather meal product from six US states and China were examined. Since arsenic toxicity is highly species-dependent, speciation analysis using HPLC/ICPMS was performed to determine the biological relevance of detected arsenic. Arsenic was detected in all samples (44-4100?gkg(-1)) and speciation analyses revealed that inorganic forms of arsenic dominated, representing 37 - 83% of total arsenic. Roxarsone was not detected in the samples (&lt;20?g As kg(-1)). Feather meal products represent a previously unrecognized source of arsenic in the food system, and may pose additional risks to humans as a result of its use as an organic fertilizer and when animal waste is managed.",
Arsenic,1022002,"Genotypic differences in arsenic, mercury, lead and cadmium in milled rice (Oryza sativa L.) Abstract: The contents of arsenic, mercury, lead and cadmium in milled rice were determined. Among 216 genotypes, the As, Hg, Pb and Cd contents were ranged from 5.06 to 296.45, 2.46 to 65.85, 4.16 to 744.95 and 5.91 to 553.40 ng/g, respectively. Six genotypes with lower contents of toxic metal elements were selected. The averages of As and Pb contents for indica rice were higher than those of japonica rice, while the averages of Hg and Cd contents were in contrast. Compared with white brown rice, the milled rice from black and red brown rice contained lower contents of four elements. Significant negative correlation was found between As content and alkaline spread value. Significant correlations were observed between As and aspartic acid (Asp) content, Hg and Asp or leucine contents, Pb and cysteine or methionine contents. Cd content was significantly negatively correlated with protein and 14 amino acid contents.",
Arsenic,1337650,"Genome-wide Identification and Quantitative Analysis of Cleaved tRNA Fragments Induced by Cellular Stress Abstract: Certain stress conditions can induce cleavage of tRNAs around the anticodon loop via the use of the ribonuclease angiogenin. The cellular factors that regulate tRNA cleavage are not well known. In this study we used normal and eIF2? phosphorylation-deficient mouse embryonic fibroblasts and applied a microarray-based methodology to identify and compare tRNA cleavage patterns in response to hypertonic stress, oxidative stress (arsenite), and treatment with recombinant angiogenin. In all three scenarios mouse embryonic fibroblasts deficient in eIF2? phosphorylation showed a higher accumulation of tRNA fragments including those derived from initiator-tRNA(Met). We have shown that tRNA cleavage is regulated by the availability of angiogenin, its substrate (tRNA), the levels of the angiogenin inhibitor RNH1, and the rates of protein synthesis. These conclusions are supported by the following findings: (i) exogenous treatment with angiogenin or knockdown of RNH1 increased tRNA cleavage; (ii) tRNA fragment accumulation was higher during oxidative stress than hypertonic stress, in agreement with a dramatic decrease of RNH1 levels during oxidative stress; and (iii) a positive correlation was observed between angiogenin-mediated tRNA cleavage and global protein synthesis rates. Identification of the stress-specific tRNA cleavage mechanisms and patterns will provide insights into the role of tRNA fragments in signaling pathways and stress-related disorders.",
Arsenic,1021839,"Metal speciation studies in the aquifer sediments of Semria Ojhapatti, Bhojpur District, Bihar Abstract: The pollution of aquifer sediments by heavy metals has assumed serious concern due to their toxicity and accumulative behavior. Changes in environmental conditions can strongly influence the behavior of both essential and toxic elements by altering the forms in which they occur and therefore quantification of the different forms of metal is more meaningful than total metal concentrations. In this study, fractionation of metal ions in aquifer sediments of Semria Ojhapatti area, Bhojpur district, Bihar has been studied to determine the ecotoxic potential of metal ions. The investigations suggest that iron, copper, and arsenic have a tendency to remain associated in the following order residual &gt; reducible &gt; acid-soluble &gt; oxidizable; manganese and zinc have tendency to be associated as residual &gt; acid-soluble &gt; reducible &gt; oxidizable. The risk assessment code reveals that manganese and zinc occur in significant concentration in acid-soluble fraction and therefore comes under the high risk category and can easily enter the food chain. Most of the iron, copper, and arsenic occur as immobile fraction (i.e. residual) followed by its presence in reducible fraction and would pose threat to the water quality due to changing redox conditions. The metal enrichment factor in the study area shows moderate to significant metal enrichment in the aquifer sediments which may pose a real threat in near future. The geo-accumulation index of metals also shows that the metals lie in the range of strongly contaminated (for iron at shallow depths) to moderately contaminated to uncontaminated values.",
Arsenic,1070336,"A preliminary assessment of low level arsenic exposure and diabetes mellitus in Cyprus Abstract: ABSTRACT: BACKGROUND: A preliminary study was undertaken in a community of Cyprus where low-level arsenic (As) concentrations were recently detected in the groundwater that was chronically used to satisfy potable needs of the community. The main objective of the study was to assess the degree of association between orally-ingested As and self-reported type-2 diabetes mellitus (DM) in 317 adult (>18 years old) volunteers. METHODS: Cumulative lifetime As exposure (CLAEX) (mg As) was calculated using the median As concentrations in water, individual reported daily water consumption rates, and lifetime exposure duration. Logistic regression models were used to model the probability of self-reported DM and calculate odds ratios in univariate and multivariate models. RESULTS: Significantly higher (p<0.02) CLAEX values were reported for the diabetics (median = 999 mg As) versus non-diabetics (median = 573 mg As), suggesting that As exposure could perhaps be related to the prevalence of DM in the study area, which was 7.0 %. The odds ratio (OR) for DM, comparing participants in the 80th versus the 20th percentiles of low-level As CLAEX index values, was 5.0 (1.03, 24.17), but after adjusting for age, smoking, education, and fish consumption, the As exposure effect on DM was not significant. CONCLUSIONS: Further research is needed to improve As exposure assessment for the entire Cypriot population while assessing the exact relationship between low-level As exposure and DM.",
Arsenic,1597337,"Arsenic mobilization by citrate and malate from a red mud-treated contaminated soil Abstract: The mobility and bioavailability of As in the soil-plant system can be affected by a number of organic acids that originate from the activity of plants and microorganisms. In this study we evaluated the ability of citrate and malate anions to mobilize As in a polluted subacidic soil (UP soil) treated with red mud (RM soil). Both anions promoted the mobilization of As from UP and RM soils, with citrate being more effective than malate. The RM treatment induced a greater mobility of As. The amounts of As released in RM and UP soils treated with 3.0 mmol L citric acid solution were 2.78 and 1.83 ?mol g respectively, whereas an amount equal to 1.73 and 1.06 ?mol g was found after the treatment with a 3.0 mmol L malic acid solution. The release of As in both soils increased with increasing concentration of organic acids, and the co-release of Al and Fe in solution also increased. The sequential extraction showed that Fe/Al (oxi)hydroxides in RM were the main phases involved in As binding in RM soil. Two possible mechanisms could be responsible for As solubilization: (i) competition of the organic anions for As adsorption sites and (ii) partial dissolution of the adsorbents (e.g., dissolution of iron and aluminum oxi-hydroxides) induced by citrate or malate and formation of complexes between dissolved Fe and Al and organic anions. This is the first report on the effect of malate and citrate on the As mobility in a polluted soil treated with RM.",
Arsenic,1794780,"Characterization of melioribacter roseus gen. nov., sp nov., a novel facultatively anaerobic thermophilic cellulolytic bacterium from the class Ignavibacteria, and a proposal of a novel bacterial phylum ignavibacteriae Abstract: A novel moderately thermophilic, facultatively anaerobic chemoorganotrophic bacterium strain P3M-2(T) was isolated from a microbial mat developing on the wooden surface of a chute under the flow of hot water (46°C) coming out of a 2775-m-deep oil exploration well (Tomsk region, Russia). Strain P3M-2(T) is a moderate thermophile and facultative anaerobe growing on mono-, di- or polysaccharides by aerobic respiration, fermentation or by reducing diverse electron acceptors [nitrite, Fe(III), As(V)]. Its closest cultivated relative (90.8% rRNA gene sequence identity) is Ignavibacterium album, the only chemoorganotrophic member of the phylum Chlorobi. New genus and species Melioribacter roseus are proposed for isolate P3M-2(T) . Together with I.?album, the new organism represents the class Ignavibacteria assigned to the phylum Chlorobi. The revealed group includes a variety of uncultured environmental clones, the 16S rRNA gene sequences of some of which have been previously attributed to the candidate division ZB1. Phylogenetic analysis of M.?roseus and I.?album based on their 23S rRNA and RecA sequences confirmed that these two organisms could represent an even deeper, phylum-level lineage. Hence, we propose a new phylum Ignavibacteriae within the Bacteroidetes-Chlorobi group with a sole class Ignavibacteria, two families Ignavibacteriaceae and Melioribacteraceae and two species I.?album and M.?roseus. This proposal correlates with chemotaxonomic data and phenotypic differences of both organisms from other cultured representatives of Chlorobi. The most essential differences, supported by the analyses of complete genomes of both organisms, are motility, facultatively anaerobic and obligately organotrophic mode of life, the absence of chlorosomes and the apparent inability to grow phototrophically.",
Arsenic,2343469,"Flow and sorption controls of groundwater arsenic in individual boreholes from bedrock aquifers in central Maine, USA Abstract: To understand the hydrogeochemical processes regulating well water arsenic (As) evolution in fractured bedrock aquifers, three domestic wells with [As] up to 478?g/L are investigated in central Maine. Geophysical logging reveals that fractures near the borehole bottom contribute 70-100% of flow. Borehole and fracture water samples from various depths show significant proportions of As (up to 69%) and Fe (93-99%) in particulates (&gt;0.45?m). These particulates and those settled after a 16-day batch experiment contain 560-13,000mg/kg of As and 14-35% weight/weight of Fe. As/Fe ratios (2.5-20mmol/mol) and As partitioning ratios (adsorbed/dissolved [As], 20,000-100,000L/kg) suggest that As is sorbed onto amorphous hydrous ferric oxides. Newly drilled cores also show enrichment of As (up to 1300mg/kg) sorbed onto secondary iron minerals on the fracture surfaces. Pumping at high flow rates induces large decreases in particulate As and Fe, a moderate increase in dissolved [As] and As(III)/As ratio, while little change in major ion chemistry. The ?D and ?(18)O are similar for the borehole and fracture waters, suggesting a same source of recharge from atmospheric precipitation. Results support a conceptual model invoking flow and sorption controls on groundwater [As] in fractured bedrock aquifers whereby oxygen infiltration promotes the oxidation of As-bearing sulfides at shallower depths in the oxic portion of the flow path releasing As and Fe; followed by Fe oxidation to form Fe oxyhydroxide particulates, which are transported in fractures and sorb As along the flow path until intercepted by boreholes. In the anoxic portions of the flow path, reductive dissolution of As-sorbed iron particulates could re-mobilize As. For exposure assessment, we recommend sampling of groundwater without filtration to obtain total As concentration in groundwater.",
Arsenic,8294,"Arsenic and SCE in human lymphocytes Abstract: The effects of tri- and penta-valent arsenic compounds on sister-chromatid exchange (SCE) in both G0 and 5-bromodeoxyuridine (BrdU) substituted chromosomes was investigated. Of 4 donors whose lymphocytes were exposed to sodium arsenate for 2 cell cycles 1 showed an increase, 2 a decrease, and 1 neither an increase or decrease over baseline levels. Exposure to sodium arsenite produced a similar result with 2 of 4 donors showing a significant increase in SCE. G0 lymphocytes exposed to either sodium arsenate or sodium arsenite did not show increased SCE. These results indicate that although arsenic can induce SCEs in human lymphocytes, there is considerable variation in SCE response among individuals. Furthermore, the data suggest that the increased SCEs seen in patients exposed to arsenic may be due to the patient's condition and not arsenic exposure.",
Arsenic,732017,"Ascorbic acid and alpha-tocopherol as potent modulators of apoptosis on arsenic induced toxicity in rats Abstract: Apoptosis or programmed cell death (PCD) is a genetically regulated cellular, physiological and biochemical suicidal mechanism that plays a crucial role in the development and defense of homeostasis, in which the cell participates in its own demise via a cascade of molecular interactions. PCD can be modulated by various stimuli including infectious agents or drugs. Arsenic is one among inducible toxic agent that triggers apoptosis via free radical generation. Since the generation of free radicals during the metabolism of arsenic is thought to be involved in arsenic toxicosis, understanding the deleterious effects caused by the ROS that attack the vital molecules like DNA has become important. The present work was conducted to evaluate the regulatory effect exerted by Vitamin C and Vitamin E upon the apoptotic process, which can be assessed by the presence of cells with apoptosis associated DNA breaks and characterize the role of TNF-alpha and caspase-3 in rats intoxicated with arsenic. Male albino rats of wistar strain (120-150 g) were used in this study and are further divided into seven groups. We observed that ascorbate and alpha-tocopherol selectively altered the extent of DNA damage by reducing TNF-alpha level and inhibiting the activation of caspase cascade, from these observations it is strongly believed that the present vitamins supplementation perspective, though observed in animal model, will have sustainable curative value among the already afflicted populations, neutralizing impact on freshly emerging arsenicosis scenario and possible proactive protection to those potentially susceptible to arsenicals exposure.",
Arsenic,1936031,"Arsenic input into the catchment of the River Caudal (Northwestern Spain) from abandoned Hg mining works: effect on water quality Abstract: In Asturias (NW Spain) there are many abandoned mines, of which Hg mines are of particular significance from an environmental point of view, due to the presence of Hg and particularly As, which is found either in the form of specific (orpiment and realgar) or non-specific minerals (As-rich pyrite). The instability of these minerals leads to the presence of As-rich mine drainage and spoils heap leachates that enter surface waters or groundwaters. A study including the three most important Hg mines in the region (La Soterraña, Los Rueldos and El Terronal) has been conducted. Watercourses flowing through these mining areas are tributaries of the River Caudal, one of the most important rivers in the area. High concentrations of As were found in some of these waters, which were monitored over a period of three hydrological years and classified according to a water quality index. Those waters sampled close to the mines are generally of poor-to-bad quality, with low alkalinity and in some cases high metal content, but the quality of these waters improves with distance from the mines. The average mass load of As entering the River Caudal has been evaluated as: 200, 12 and 9,800 kg year(-1) from La Soterraña, Los Rueldos and El Terronal mine sites, respectively. Despite the constant input of about 10 tonnes of As per year, the total As concentration remains below analytical detection thresholds on account of the river's high water flow. Nevertheless, an important part of this As load is presumably retained in the river sediments, representing a potential risk of pollution of the aquatic ecosystems.",
Arsenic,628409,"Differential effects of trivalent and pentavalent arsenicals on cell proliferation and cytokine secretion in normal human epidermal keratinocytes Abstract: There is strong evidence from epidemiologic studies of an association between chronic exposure to inorganic arsenic (iAs) and hyperpigmentation, hyperkeratosis, and neoplasia in the skin. Although it is generally accepted that methylation is a mechanism of arsenic detoxification, recent studies have suggested that methylated arsenicals also have deleterious biological effects. In these studies we compare the effects of inorganic arsenicals (arsenite (iAs(III)) and arsenate (iAs(V))) and trivalent and pentavalent methylated arsenicals (methylarsine oxide (MAs(III)O), complex of dimethylarsinous acid with glutathione (DMAs(III)GS), methylarsonic acid (MAs(V)), and dimethylarsinic acid (DMAs(V))) in human keratinocyte cultures. Viability testing showed that the relative toxicities of the arsenicals were as follows: iAs(III) > MAs(III)O > DMAs(III)GS > DMAs(V) > MAs(V) > iAs(V). Trivalent arsenicals induced an increase in cell proliferation at concentrations in the 0.001 to 0.01 microM range, while at high concentrations (>0.5 microM) cell proliferation was inhibited. Pentavalent arsenicals did not stimulate cell proliferation. As seen in the viability studies, the methylated forms of As(V) were more cytotoxic than iAs(V). Exposure to low doses of trivalent arsenicals stimulated secretion of the growth-promoting cytokines, granulocyte macrophage colony stimulating factor and tumor necrosis factor-alpha. DMAs(V) reduced cytokine secretion at concentrations at which proliferation and viability were not affected. These data suggest that methylated arsenicals, products of the metabolic conversion of inorganic arsenic, can significantly affect viability and proliferation of human keratinocytes and modify their secretion of inflammatory and growth-promoting cytokines. Copyright 2001 Academic Press.",
Arsenic,1248938,"Interpreting variability in population biomonitoring data: Role of elimination kinetics Abstract: Biomarker concentrations in spot samples of blood and urine are implicitly interpreted as direct surrogates for long-term exposure magnitude in a variety of contexts including (1) epidemiological studies of potential health outcomes associated with general population chemical exposure, and (2) cross-sectional population biomonitoring studies. However, numerous factors in addition to exposure magnitude influence biomarker concentrations in spot samples, including temporal variation in spot samples because of elimination kinetics. The influence of half-life of elimination relative to exposure interval is examined here using simple first-order pharmacokinetic simulations of urinary concentrations in spot samples collected at random times relative to exposure events. Repeated exposures were modeled for each individual in the simulation with exposure amounts drawn from lognormal distributions with varying geometric standard deviations. Relative variation in predicted spot sample concentrations was greater than the variation in underlying dose distributions when the half-life of elimination was shorter than the interval between exposures, with the degree of relative variation increasing as the ratio of half-life to exposure interval decreased. Results of the modeling agreed well with data from a serial urine collection data set from the Centers for Disease Control. Data from previous studies examining intra-class correlation coefficients for a range of chemicals relying upon repeated sampling support the importance of considering the half-life relative to exposure frequency in design and interpretation of studies using spot samples for exposure classification and exposure estimation. The modeling and data sets presented here provide tools that can assist in interpretation of variability in cross-sectional biomonitoring studies and in design of studies utilizing biomonitoring data as markers for exposure.",
Arsenic,1579286,"SPE HG-AAS method for the determination of inorganic arsenic in rice-results from method validation studies and a survey on rice products Abstract: The present paper describes the development, validation and application of a method for inorganic arsenic (iAs) determination in rice samples. The separation of iAs from organoarsenic compounds was done by off-line solid-phase extraction (SPE) followed by hydride generation atomic absorption spectrometry (HG-AAS) detection. This approach was earlier developed for seafood samples (Rasmussen et al., Anal Bioanal Chem 403:2825-2834, 2012) and has in the present work been tailored for rice products and further optimised for a higher sample throughput and a lower detection limit. Water bath heating (90 °C, 60 min) of samples with dilute HNO3 and H2O2 solubilised and oxidised all iAs to arsenate (As(V)). Loading of buffered sample extracts (pH 6?±?1) followed by selective elution of arsenate from a strong anion exchange SPE cartridge enabled the selective iAs quantification by HG-AAS, measuring total arsenic (As) in the SPE eluate. The in-house validation gave mean recoveries of 101-106 % for spiked rice samples and in two reference samples. The limit of detection was 0.02 mg kg(-1), and repeatability and intra-laboratory reproducibility were less than 6 and 9 %, respectively. The SPE HG-AAS method produced similar results compared to parallel high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (ICP-MS) analysis. The SPE separation step was tested collaboratively, where the laboratories (N?=?10) used either HG-AAS or ICP-MS for iAs determination in a wholemeal rice powder. The trial gave satisfactory results (HorRat value of 1.6) and did not reveal significant difference (t test, p?&gt;?0.05) between HG-AAS and ICP-MS quantification. The iAs concentration in 36 rice samples purchased on the Danish retail market varied (0.03-0.60 mg kg(-1)), with the highest concentration found in a red rice sample.",
Arsenic,734880,"Involvement of oxidative stress and activation of aryl hydrocarbon receptor in elevation of CYP1A1 expression and activity in lung cells and tissues by arsenic: an in vitro and in vivo study Abstract: Epidemiological evidence indicated that there was a synergistic interaction between arsenic and cigarette smoke on enhancement of lung cancer risk. Benzo[a]pyrene (B[a]P), a component in cigarette smoke, is one of the most carcinogenic compounds known. Animal studies have demonstrated that there were increased benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) adduct formation and lung tumorigenesis in animals when they were coexposed to B[a]P and arsenic. Since BPDE adduct is a by-product of B[a]P metabolism, elevation of B[a]P metabolism by arsenic is suspected. However, the effects of arsenic on cytochrome P450 1A1 (CYP1A1) status (expression and activity), which is essential for B[a]P metabolism, either in lung cells or in lung tissues, are never demonstrated. We hypothesized that arsenic would enhance aryl hydrocarbon receptor (AhR) activation leading to CYP1A1 expression and activity in lung cells. Indeed, our present study successfully demonstrated the elevation of CYP1A1 messenger RNA expression in H1355 cells, a human lung adenocarcinoma cell line, as well as CYP1A1 expression and activity in lung tissues of arsenic-exposed mice. We further demonstrated that this elevation of CYP1A1 expression could be effectively blocked with AhR antagonist, 3',4'-dimethoxyflavone, indicating that the arsenic-induced CYP1A1 expression and activity were via AhR activation. Furthermore, we found that arsenic-induced AhR activation and -enhanced CYP1A1 expression can be further increased by a prooxidant, buthionine-(S,R)-sulfoximine, and suppressed by antioxidants, such as N-acetylcysteine and catalase. Our findings provided clear evidence that arsenic can enhance CYP1A1 expression and activity via AhR activation, and the arsenic-induced AhR activation is probably triggered by oxidative stress.",
Arsenic,1022218,"Oxidative stress by inorganic arsenic: Modulation by thyroid hormones in rat Abstract: Arsenic toxicity is attributed mainly to lipid peroxidation and oxidative stress. We therefore studied the modulatory effects of thyroid hormones on arsenic toxicity in rat on lipid peroxidation and oxidative stress. Thyroid hormones, through a mechanism unknown at present, inhibit arsenic accumulation in liver and kidney. Mobilization of arsenic apparently diminishes lipid peroxidation and improves reduced glutathione status, two biochemical demands of combating arsenic toxicity. Results are discussed in reference to the effect of thyroid hormones on microsomal metabolism of arsenic. Arsenic is less toxic in hyperthyroid than in hypothyroid rats. A physiological antagonism between arsenic and thyroxine is discussed.",
Arsenic,1339338,"Translational attenuation differentially alters the fate of disease-associated fibulin proteins Abstract: Mutations in fibulin proteins that cause cellular secretion deficiencies are linked to a variety of diseases, ranging from retinopathies to cutis laxa (CL). One secretion-deficient fibulin mutant, R345W fibulin-3, causes the macular dystrophy malattia leventinese by increased endoplasmic reticulum retention and/or extracellular misfolding. Herein, we report that small-molecule activation of the PERK arm of the unfolded protein response partially rescues R345W secretion deficiencies through translational attenuation mediated by eIF2? phosphorylation. Enhanced mutant fibulin-3 secretion can also be achieved by activation of a PERK-independent eIF2? kinase through arsenite treatment and is independent of activating transcription factor 4 signaling and protein translation. However, this translational attenuation strategy was unsuccessful for enhancing the secretion deficiencies of fibulin-5 mutants associated with age-related macular degeneration or CL. While lowered growth temperature enhanced the secretion of mutants associated with CL (C217R and S227P), these effects were not mediated through translational attenuation. In stark contrast to the situation with fibulin-3, protein translation was required for efficient wild-type and mutant fibulin-5 secretion. These data suggest that alteration of specific cellular signaling pathways and proteostasis network components can differentially influence fibulin fate, a hypothesis that could be exploited as a therapy for fibulin-related diseases.",
Arsenic,1936068,"Mitochondrial phosphate transport during nutrient stimulation of INS-1E insulinoma cells Abstract: Here, we have investigated the role of inorganic phosphate (Pi) transport in mitochondria of rat clonal ?-cells. In ?-toxin-permeabilized INS-1E cells, succinate and glycerol-3-phosphate increased mitochondrial ATP release which depends on exogenous ADP and Pi. In the presence of substrates, addition of Pi caused mitochondrial matrix acidification and hyperpolarisation which promoted ATP export. Dissipation of the mitochondrial pH gradient or pharmacological inhibition of Pi transport blocked the effects of Pi on electrochemical gradient and ATP export. Knock-down of the phosphate transporter PiC, however, neither prevented Pi-induced mitochondrial activation nor glucose-induced insulin secretion. Using (31)P NMR we observed reduction of Pi pools during nutrient stimulation of INS-1E cells. Interestingly, Pi loss was less pronounced in mitochondria than in the cytosol. We conclude that matrix alkalinisation is necessary to maintain a mitochondrial Pi pool, at levels sufficient to stimulate energy metabolism in insulin-secreting cells beyond its role as a substrate for ATP synthesis.",
Arsenic,1350691,Detection of a DMPS-MMA(III) complex during treatment of massive arsenic ingestion Abstract: ,
Arsenic,1579345,"Genetic and Non-genetic Predictors of LINE-1 Methylation in Leukocyte DNA Abstract: BACKGROUND: Altered DNA methylation has been associated with various diseases. OBJECTIVE: To evaluate the association between levels of methylation in leukocyte DNA at long interspersed nuclear element 1 (LINE-1) and genetic and non-genetic characteristics of 892 control participants from the Spanish Bladder Cancer/EPICURO Study. METHODS: We determined LINE-1 methylation levels by pyrosequencing. Individual data included demographics, smoking status, nutrient intake, toenail concentrations of 12 trace elements, xenobiotic metabolism gene variants, and 515 polymorphisms among 24 genes in the one-carbon metabolism pathway. To assess the association between LINE-1 methylation levels (percentage of methylated cytosines) and potential determinants, we estimated beta coefficients (?) by robust linear regression. RESULTS: Females had lower levels of LINE-1 methylation than males (?=-0.7, p-value=0.02). Blond tobacco smokers showed lower methylation than non-smokers (?=-0.7, p-value=0.03). Arsenic toenail concentration was inversely associated with LINE-1 methylation (?=-3.6, p-value=0.003). By contrast, iron (?=0.002, p-value=0.009) and nickel (?=0.02, p-value=0.004) were positively associated with LINE-1 methylation. SNPs in DNMT3A (rs7581217-per allele, ?=0.3, p-value=0.002), TCN2 (rs9606756-GG, ?=1.9, p-value=0.008; rs4820887-AA, ?=4.0, p-value=4.8x10(-7); rs9621049-TT, ?=4.2, p-value=4.7x10(-9)), AS3MT (rs7085104-GG, ?=0.7, p-value=0.001), SLC19A1 (rs914238, TC vs. TT: ?=0.5 and CC vs. TT: ?=-0.3, global p-value=0.0007) and MTHFS (rs1380642, CT vs. CC: ?=0.3 and TT vs. CC; ?=-0.8, global p-value=0.05) were associated with LINE-1 methylation. CONCLUSIONS: We identified several characteristics, environmental factors, and common genetic variants that predicted DNA methylation among study participants.",
Arsenic,627478,"Detecting arsenic-related skin lesions: Experiences from a large community-based survey in Bangladesh Abstract: A cross-sectional survey was conducted in Matlab, Bangladesh, to determine the prevalence of skin lesions (a three-step procedure) associated with arsenic exposure and discuss validity and feasibility in relation to recommended screening algorithms. Cases with skin lesions were identified by screening above 4 years of age (n = 166,934). Trained field teams conducted a careful house-to-house screening and identified 1682 individuals with skin lesions, who were referred to physicians for confirmation. Physicians diagnosed 579 cases as probable and documented all these with digital photographs. Two experts inspected all photographs for consensus agreement that was reached for 504 cases. Using the experts' opinions as reference, the positive predictive value of the physicians' diagnosis was 87% (male = 82% vs. female = 94%; p < 0.01). The physicians had difficulties in separating arsenic-induced keratosis from differential diagnoses, while probability for correct diagnosis was high for arsenic-related pigmentation changes. Including information on current arsenic concentration in drinking water (which was masked at time of skin examination) or urine in the diagnostic algorithm should have increased the number of false negative cases. In the present transition of drinking water sources these markers of current exposure levels provide no information on past exposure. A 2-3 step procedure with house-to-house screening and clinic-based confirmation of arsenic-induced skin lesions is a feasible approach. Information on arsenic concentration in current water sources or in urine should not have improved the precision in the diagnosis. These results may have policy implications for community screening of arsenic-related skin lesions in Bangladesh and elsewhere.",
Arsenic,2149131,"Unexpected genomic variability in clinical and environmental strains of the pathogenic yeast Candida parapsilosis Abstract: Invasive candidiasis is the most commonly reported invasive fungal infection worldwide. Although C. albicans remains the main cause, the incidence of emerging Candida species such as C. parapsilosis is increasing. It has been postulated that C. parapsilosis clinical isolates result from a recent global expansion of a virulent clone. However, the availability of a single genome for this species has so far prevented testing this hypothesis at genomic scales. We here present the sequence of three additional strains from clinical and environmental samples. Our analyses reveal unexpected patterns of genomic variation, shared among distant strains, that argue against the clonal expansion hypothesis. All strains carry independent expansions involving an arsenite transporter homolog, pointing to the existence of directional selection in the environment, and independent origins of the two clinical isolates. Furthermore we report the first evidence for the existence of recombination in this species. Altogether, our results shed new light onto the dynamics of genome evolution in C. parapsilosis.",
Arsenic,2088491,"Atrazine is primarily responsible for the toxicity of long-term exposure to a combination of atrazine and inorganic arsenic in the nigrostriatal system of the albino rat Abstract: Chronic and simultaneous exposure to a variety of chemicals present in the environment is an unavoidable fact. However, given the complexity of studying chemical mixtures, most toxicological studies have focused on the effects of short-term exposure to single substances. The aim of this study was to evaluate the effects on the nigrostriatal system of the chronic, simultaneous exposure to two widely distributed substances that have been identified as potential dopaminergic system toxicants, inorganic arsenic (iAs) and atrazine (ATR). Six groups of rats were treated daily for one year with atrazine (10mg ATR/kg), inorganic arsenic (0.5 or 50mg iAs/L of drinking water),or a combination of ATR+0.5mg iAs/L or ATR+50mg iAs/L. The 50mg iAs/L group showed locomotor hypoactivity, while all treatments decreased motor coordination in contrast no effects of treatment were found on the place and response learning tasks. Regarding markers for liver and muscle damage, there were no differences between groups in creatine kinase (CK) or aspartate transaminase (AST) activities, while decreases in lactate dehydrogenase (LDH) levels were found in some exposed groups. The striatal DA content was significantly reduced in ATR, 0.5mg iAs/L, ATR+0.5mg iAs/L, and ATR+50mg iAs/L groups, in comparison to the control group. The number of mesencephalic tyrosine hydroxylase positive cells decreased in the ATR and ATR+0.5mg iAs/L groups compared to the control. In contrast, immunoreactivity to cytochrome oxidase was reduced compared to the control in all treated groups, except for the group treated with 0.5 iAs mg alone. Our results indicate that ATR has deleterious effects on dopaminergic neurons and that the combination of ATR and iAs does not exacerbate these effects.",
Arsenic,628531,"Mono- and dimethylation of arsenic in rat liver cytosol in vitro Abstract: Production of methylarsonate and dimethylarsinate from radiolabelled [73As]arsenite and [73As]arsenate was examined in an assay system that contained cytosol prepared from a 20% homogenate (w/v) of livers from 8–10-week-old male Fischer 344 rats. After a 60-min incubation at 37 °C with added S-adenosylmethionine and glutathione, up to 50% of carrier-free [73As]arsenite and about 15% of carrier-free [73As]arsenate were methylated. Incubation of cytosol at 100 °C for 1 min before addition to the assay system completely abolished methylation of arsenite. Production of methylarsonate increased in proportion to the arsenite concentration in the assay system; however, 50 ?M arsenite inhibited production of dimethylarsinate. Methylarsonate production from carrier-free [73As]arsenite was not dependent on addition of exogenous S-adenosylmethionine to the assay system. Addition of 0.1 mM S-adenosylmethionine maximized dimethylarsinate production. Addition of 0.1 or 1.0 mM S-adenosylhomocysteine decreased methylation of arsenite, especially dimethylarsinate production. Omission of glutathione from the assay system nearly abolished the methylation of arsenite. Addition of exogenous glutathione to the assay system (up to 20 mM) decreased protein binding of arsenic and increased the production of methylarsonate and dimethylarsinate. The effects of sodium selenite, mercuric chloride, EDTA, p-anisic acid and 2,3-dichloro-?methylbenzylamine on the methylation of arsenite were determined. Addition of 10 ?M selenite to the assay system nearly abolished the formation of either methylated species. Addition of 1 or 10 ?M mercuric chloride inhibited dimethylarsinate production in a concentration-dependent manner but had little effect on methylarsonate yield. Addition of 10 mM EDTA to the assay system inhibited formation of both methylated metabolites, suggesting that an endogenous divalent cation might be involved in enzymatic methylation of arsenic. Neither p-anisic acid, an inhibitor of cytosolic methyltransferases, nor 2,3-dichloro-?methylbenzylamine, an inhibitor of microsomal methyltransferases, inhibited the conversion of inorganic arsenic to mono- or dimethylated metabolites.",
Arsenic,1018445,"Metabolites of arsenic induced tetraploids and mitotic arrest in cultured cells Abstract: The toxic effects of arsenic compounds on cell divisionwere studied, using Chinese hamster V79 cells. Seven arsenic compounds weretested. Inorganic arsenic compounds (arsenite and arsenate), which have beenfound in drinking water, inhibited cell growth at very low concentrations. Monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and trimethylarsineoxide (TMAO), which are methylated metabolites of inorganic arsenics, wereless cytotoxic than the inorganic arsenics themselves. The cytotoxicity ofthe three methylated metabolites decreased as the number of methyl groupsincreased. Arsenobetaine (AsBe) and arsenocholine (AsC), which have beenfound in some marine products, did not show any cytotoxicity. Threemethylated metabolites; MMA, DMA and TMAO induced mitotic arrest. Tetraploidyproduction was observed in cells exposed to DMA or TMAO. Arsenite, arsenate,AsBe and AsC did not induce mitotic arrest or tetraploids. These resultssuggest that MMA, DMA and TMAO exert some effect on cell division inmetaphase and may thereby give some clue as to the carcinogenic mechanism ofarsenic.",
Arsenic,1597356,"Biopolymer-reinforced synthetic granular nanocomposites for affordable point-of-use water purification Abstract: Creation of affordable materials for constant release of silver ions in water is one of the most promising ways to provide microbially safe drinking water for all. Combining the capacity of diverse nanocomposites to scavenge toxic species such as arsenic, lead, and other contaminants along with the above capability can result in affordable, all-inclusive drinking water purifiers that can function without electricity. The critical problem in achieving this is the synthesis of stable materials that can release silver ions continuously in the presence of complex species usually present in drinking water that deposit and cause scaling on nanomaterial surfaces. Here we show that such constant release materials can be synthesized in a simple and effective fashion in water itself without the use of electrical power. The nanocomposite exhibits river sand-like properties, such as higher shear strength in loose and wet forms. These materials have been used to develop an affordable water purifier to deliver clean drinking water at US $2.5/y per family. The ability to prepare nanostructured compositions at near ambient temperature has wide relevance for adsorption-based water purification.",
Arsenic,2337102,"Mössbauer study of magnetic fluctuation in the iron-arsenic layer of Sr2VO3FeAs Abstract: Mössbauer spectra of the freshly prepared Sr2VO3FeAs compound have been measured under different temperatures. We observed a variation of the spectral shape with decreasing temperature. The obvious diminution of quadrupole splitting occurred at about 63K is ascribed to the weak influence of the ferromagnetic transition of the V-O layer to the spatial distribution of Fe-3d electrons, whereas the influence of the antiferromagnetic transition in the V-O layer is negligible. Below the superconducting transition temperature the distinct enhancement of the spectral area and the simultaneous increase of the line width suggest the emergence of magnetic fluctuations in the FeAs layer. Our experimental results strongly indicate the coexistence of magnetism and superconductivity in the freshly prepared Sr2VO3FeAs compound.",
Arsenic,656902,"Effects of an epidermal growth factor receptor inhibitor on arsenic associated toxicity in the rat bladder epithelium Abstract: Arsenite (AsIII), an inorganic arsenical, is a known human carcinogen, inducing tumors of the skin, urinary bladder and lung. It is known to be metabolized to organic methylated arsenicals in vivo. AsIII has been reported to have the ability to up-regulate the epidermal growth factor receptor (EGFR)-associated pathway in epithelial cells, including human urothelial cells in vitro. EGFR is a cell-surface receptor belonging to the ErbB family of receptor tyrosine kinases, and the EGFR-associated signaling pathway has been reported to play an important role in carcinogenesis and cancer progression, including in bladder cancer. In this study, we investigated the growth effects of AsIII and an organic trivalent arsenical, dimethylarsinous acid (DMAIII), and the effects of co-exposure of gefitinib, an EGFR inhibitor, with AsIII to a rat urothelial cell line (MYP3). We also investigated the effects of co-administration of dietary AsIII and gefitinib in vivo. In vitro, concentrations of 1.0 ?M AsIII or 0.5 ?M DMAIII induced cytotoxicity. However, lower concentrations of AsIII treatment had a slight mitogenic growth effect whereas lower concentrations of DMAIII did not. Gefitinib blocked AsIII-induced cell growth in vitro. In vivo, a high dose of gefitinib alone induced slight urothelial cytotoxicity, and did not reduce cytotoxicity and regenerative cell proliferation when co-administered with AsIII. The majority of arsenic metabolites present in the urine of AsIII-treated rats were organic arsenicals, mainly dimethylarsinic acid (DMAV). AsIII was also present, and its concentration was higher than the concentration required to produce cytotoxicity in vitro. These data suggest that an EGFR inhibitor has the ability to block AsIII-induced cell proliferation in vitro but not in vivo in a short-term study.",
Arsenic,1015676,"Tumors and proliferative lesions in adult offspring after maternal exposure to methylarsonous acid during gestation in CD1 mice Abstract: Developmental exposure to inorganic arsenic is carcinogenic in humans and mice, and adult offspring of mice exposed to inorganic arsenic can develop tumors of the lung, liver, adrenal, uterus, and ovary. It has been suggested that methylarsonous acid (MMA3+), a product of the biological methylation of inorganic arsenic, could be a key carcinogenic species. Thus, pregnant CD1 mice were provided drinking water containing MMA3+ at 0 (control), 12.5, or 25 parts per million (ppm) from gestational days 8 to 18. Tumors were assessed in groups of male or female (initial n = 25) offspring up to 2 years of age. In utero treatment had no effect on survival or body weights. Female offspring exhibited increases in total epithelial uterine tumors (control 0%; 12.5 ppm 26%; 25 ppm 30%), oviduct hyperplasia (control 4%; 12.5 ppm 35%; 25 ppm 43%), adrenal cortical adenoma at 25 ppm (control 0%; 12.5 ppm 9%; 25 ppm 26%), and total epithelial ovarian tumors (control 0%; 12.5 ppm 39%; 25 ppm 26%). Male offspring showed dose-related increases in hepatocellular carcinoma (control 0%; 12.5 ppm 12%; 25 ppm 22%), adrenal adenoma (control 0%; 12.5 ppm 28%; 25 ppm 17%), and lung adenocarcinoma (control 17%; 12.5 ppm 44%). Male offspring had unusual testicular lesions, including two rete testis carcinomas, two adenomas, and three interstitial cell tumors. Overall, maternal consumption of MMA3+ during pregnancy in CD1 mice produced some similar proliferative lesions as gestationally applied inorganic arsenic in the offspring during adulthood.",
Arsenic,2345601,"The transport behavior of As, Cu, Pb, and Zn during electrokinetic remediation of a contaminated soil using electrolyte conditioning Abstract: Electrokinetic remediation (also known as electrokinetics) is a promising technology for removing metals from fine-grained soils. However, few studies have been conducted regarding the transport behavior of multi-metals during electrokinetics. We investigated the transport of As, Cu, Pb, and Zn from soils during electrokinetics, the metal fractionation before and after electrokinetics, the relationships between metal transport and fractionation, and the effects of electrolyte conditioning. The main transport mechanisms of the metals were electroosmosis and electromigration during the first two weeks and electromigration during the following weeks. The direction of electroosmotic flow was from the anode to the cathode, and the metals in the dissolved and reducible-oxides fractions were transported to the anode or cathode by electromigration according to the chemical speciation of the metal ions in the pore water. Moreover, a portion of the metals that were initially in the residual fraction transitioned to the reducible and soluble fractions during electrokinetic treatment. However, this alteration was slow and resulted in decreasing metal removal rates as the electrokinetic treatment progressed. In addition, the use of NaOH, H3PO4, and Na2SO4 as electrolytes resulted in conditions that favored the precipitation of metal hydroxides, phosphates, and sulfates in the soil. These results demonstrated that metal removal was affected by the initial metal fractionation, metal speciation in the pore solution, and the physical-chemical parameters of the electrolytes, such as pH and electrolyte composition. Therefore, the treatment time, use of chemicals, and energy consumption could be reduced by optimizing pretreatment and by choosing appropriate electrolytes for the target metals.",
Arsenic,1704098,Selective Separation of Tri- and Pentavalent Arsenic in Aqueous Matrix with a Macrocycle-Immobilized Solid-Phase Extraction System Abstract: ,
Arsenic,1380173,INFLUENCE OF PH AND ORGANIC SUBSTANCE ON THE ADSORPTION OF ARSENIC ON GEOLOGIC MATERIALS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXIC ELEMENT LEACHING ACIDIC DEPOSITION,
Arsenic,1597457,STUDIES ON THE PALLADIUM AND GOLD IONS EXTRACTION WITH SOME ESTER DERIVATIVES OF CALIX[N]ARENE Abstract: ,
Arsenic,2279025,"Understanding the translation of scientific knowledge about arsenic risk exposure among private well water users in Nova Scotia Abstract: Arsenic is a class I human carcinogen that has been identified as the second most important global health concern in groundwater supplies after contamination by pathogenic organisms. Hydrogeological assessments have shown naturally occurring arsenic to be widespread in groundwater across the northeastern United States and eastern Canada. Knowledge of arsenic risk exposure among private well users in these arsenic endemic areas has not yet been fully explored but research on water quality perceptions indicates a consistent misalignment between public and scientific assessments of environmental risk. This paper evaluates knowledge of arsenic risk exposure among a demographic cross-section of well users residing in 5 areas of Nova Scotia assessed to be at variable risk (high-low) of arsenic occurrence in groundwater based on water sample analysis. An integrated knowledge-to-action (KTA) methodological approach is utilized to comprehensively assess the personal, social and local factors shaping perception of well water contaminant risks and the translation of knowledge into routine water testing behaviors. Analysis of well user survey data (n=420) reveals a high level of confidence in well water quality that is unrelated to the relative risk of arsenic exposure or homeowner adherence to government testing recommendations. Further analysis from the survey and in-depth well user interviews (n=32) finds that well users' assessments of risk are influenced by personal experience, local knowledge, social networks and convenience of infrastructure rather than by formal information channels, which are largely failing to reach their target audiences. Insights from interviews with stakeholders representing government health and environment agencies (n=15) are used to reflect on the institutional barriers that mediate the translation of scientific knowledge into public awareness and stewardship behaviors. The utilization of local knowledge brokers, community-based networks and regulatory incentives to improve risk knowledge and support routine testing among private well users is discussed.",
Arsenic,1508563,"Monitoring Response and Resistance to the Novel Arsenical Darinaparsin in an AML Patient Abstract: Acute myeloid leukemia (AML) with inversion of chromosome 3 is characterized by overexpression of EVI1 and carries a dismal prognosis. Arsenic-containing compounds have been described to be efficacious in malignancies overexpressing EVI1. Here, we describe a case of AML with inv(3)(q21q26.2) treated with the organic arsenical darinaparsin. Using a &quot;personalized medicine approach,&quot; two different arsenicals were screened for anti-leukemic effect against the patient's cells ex vivo. The most promising compound, darinaparsin, was selected for in vivo treatment. Clinical effect was almost immediate, with a normalization of temperature, a stabilization of white blood cell (WBC) counts and an increased quality of life. Longitudinal monitoring of patient response and resistance incorporating significant correlative studies on patient-derived blood samples over the two cycles of darinaparsin given to this patient allowed us to evaluate potential mechanisms of response and resistance. The anti-leukemic effects of darinaparsin correlated with inhibition of the alternative NF-?B pathway and production of the inflammatory cytokine IL-8. Emergence of resistance was suspected during treatment cycle 2 and supported by xenograft studies in nude mice. Darinaparsin resistance correlated with an attenuation of the effect of treatment on the alternative NF-?B pathway. The results from this patient indicate that darinaparsin may be a good treatment option for inv(3) AML and that inhibition of the alternative NF-?B pathway may be predictive of response. Longitudinal monitoring of disease response as well as several correlative parameters allowed for the generation of novel correlations and predictors of response to experimental therapy in a heavily pretreated patient.",
Arsenic,1597290,"The effectiveness of educational interventions to enhance the adoption of fee-based arsenic testing in Bangladesh: A cluster randomized controlled trial Abstract: Arsenic (As) testing could help 22 million people, using drinking water sources that exceed the Bangladesh As standard, to identify safe sources. A cluster randomized controlled trial was conducted to evaluate the effectiveness of household education and local media in the increasing demand for fee-based As testing. Randomly selected households (N = 452) were divided into three interventions implemented by community workers: 1) fee-based As testing with household education (HE); 2) fee-based As testing with household education and a local media campaign (HELM); and 3) fee-based As testing alone (Control). The fee for the As test was US$ 0.28, higher than the cost of the test (US$ 0.16). Of households with untested wells, 93% in both intervention groups HE and HELM purchased an As test, whereas only 53% in the control group. In conclusion, fee-based As testing with household education is effective in the increasing demand for As testing in rural Bangladesh.",
Arsenic,1508669,"Oxidative DNA damage after acute exposure to arsenite and monomethylarsonous acid in biomethylation-deficient human cells Abstract: The carcinogen inorganic arsenic (iAs) undergoes biomethylation (BMT) in some cells. The methylated metabolite, monomethylarsonous (MMA(3+)), may cause oxidative DNA damage (ODD). With chronic iAs exposure, BMT-competent cells show ODD while BMT-deficient do not. To further define these events, we studied ODD produced by acute iAs or MMA(3+) in the BMT-deficient human prostate cell line, RWPE-1. ODD, measured by the immuno-spin trapping method, was assessed after exposure to iAs or MMA(3+) alone, with the arsenic BMT inhibitor selenite or after glutathione (GSH) depletion. The expression of oxidative stress-related genes (HO-1, SOD-1, SOD-2, Nrf2 and Keap-1) was also assessed. Exposure to iAs at 24?h (0-20?µM), stimulated ODD only at levels above the LC(50) of a 48?h exposure (17?µM). If iAs induced ODD, it also activated oxidative stress-related genes. Selenium did not alter iAs-induced ODD. MMA(3+) at 24?h (0-0.5?µM) caused ODD at levels below the LC(50) of a 48?h exposure (1.5?µM), which were greatly increased by GSH depletion but not selenite. MMA(3+) induced ODD at levels not activating oxidant stress response genes. Overall, iAs induced ODD in BMT-deficient cells only at toxic levels. MMA(3+) caused ODD at non-toxic levels, independently of cellular BMT capacity and in a fashion not requiring further BMT.",
Arsenic,2088455,"Preliminary morphological and immunohistochemical changes in rat hippocampus following postnatal exposure to sodium arsenite Abstract: The effects of arsenic exposure during rapid brain growth period (RBGP) (postnatal period 4-11) on pyramidal neurons of cornu ammonis (specifically CA1 and CA3 regions) and granule cells of dentate gyrus (DG) of rat hippocampus were studied. Wistar rat pups, subdivided into the control (group I) and the experimental groups (group II, III, and IV), received distilled water and sodium arsenite (aqueous solution of 1.0, 1.5, and 2.0 mg/kg body weight, respectively) by intraperitoneal (i.p.) route. On postnatal day (PND) 12, the animals were sacrificed and brain tissue obtained. Paraffin sections (8 ?m thick) stained with Cresyl Violet (CV) were observed for morphological and morphometric parameters. Arsenic induced programmed cell death (apoptosis) was studied using Terminal deoxyribonucleotidyl transferase mediated dUTP biotin Nick End Labeling (TUNEL) technique on the paraffin sections. Microscopy revealed decreased number and isolation of pyramidal neurons in superficial layers, misalignments of pyramidal cells in stratum pyramidale (SP) of CA1 and CA3 in experimental group III and IV, and presence of polymorphic cells in subgranular zone of ectal limb of dentate gyrus (suggestive of arsenic induced proliferation and migration of granule cells in the dentate gyrus). Morphometric assessments quantified and confirmed the microscopic findings. The mean nuclear area of pyramidal cells was increased and cell density was decreased in the CA1, CA3, and DG of experimental groups in comparison to the control group. Increase in the TUNEL positive cells in DG was observed in the experimental group IV, suggestive of increased apoptosis. These observations confirm vulnerability of pyramidal (CA1, CA3) and granule cells (DG) of hippocampus during RBGP.",
Arsenic,1028860,"Arsenic content of Spanish cows' milk determined by dry ashing hydride generation atomic absorption spectrometry Abstract: The arsenic content of cows' milk consumed in Spain was determined. A procedure using dry ashing hydride generation atomic absorption spectrometry was developed for the purpose. Experimental conditions for the destruction of organic matter were established and an interference study was carried out. The method developed has a detection limit of 0.1 ng/g, a relative SD of 5%, and a recovery (mean +/- CSI) of 100 +/- 4%. The accuracy of the method was checked by analysis of a certified sample of IAEA milk powder (mean +/- CSI: certified, 4.85 +/- 0.32 ng/g; found, 5.04 +/- 0.81 ng/g). The proposed procedure was used to analyse cows' milk samples. The extremely low arsenic levels found do not present toxicological problems.",
Arsenic,2343527,"Determination and chemometric evaluation of total aflatoxin, aflatoxin B1, ochratoxin A and heavy metals content in corn flours from Turkey Abstract: Concentrations of the total aflatoxin, aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, ochratoxin A, lead, cadmium, mercury, arsenic, copper, zinc and chromium in corn flour samples were determined. Eighteen corn flour samples that were obtained from different cities and villages in Turkey and 3 corn flour samples obtained from the UK. Determination of the different toxins was carried out using HPLC instrumentation after pre-separation using immunoaffinity columns that work through a mechanism of solid-phase extraction. An ICP-MS instrument was used for the heavy metal determinations. The results obtained from HPLC and ICP-MS analyses of the corn flour samples showed that these samples contain detectable levels of most of the analytes but the mercury was at undetectable levels. A very strong statistical relationship was observed between Cr and total Aflatoxin and Aflatoxin B1; whereas Ochratoxin A was related to Cu and Zn concentrations using correlation analyses and principal component analyses. (C) 2014 Elsevier Ltd. All rights reserved.",
Arsenic,2347804,"A compositional study of Cypriot bronzes dating to the Early Iron Age using portable X-ray fluorescence spectrometry (pXRF) Abstract: A collection of 157 copper alloy artefacts from the necropolis of Palaepaphos Skates, located in south-west Cyprus, dating to the 11th-8th centuries BC, was studied and chemically analysed with a handheld pXRF instrument to determine the alloy type that was used for their production. The collection consists of Cu-Sn binary alloys. The relative concentration of the two metals seems to have been determined by the type of artefact the alloy was used to produce. The results also imply that fresh rather than recycled metal was used. The majority of the artefacts are made of a bronze with an average tin content of 8.1 +/- 2.2%. There is, however, a group of objects with a characteristic golden surface, under the patina, which was found to have a significantly higher tin concentration, that averages 18.6 +/- 2.8% Sn. The lead content in the assemblage ranges from 0.1 to 2.6%. Because lead concentration in local Cypriot ores is unusually low, its presence is interpreted as a deliberate addition even at these low concentrations. The iron content ranges from 0.1 to 1.4%, while zinc is present only in 20 artefacts, exhibiting a concentration range of 0.2-1%. Both elements are believed to be non-intentional additions to the alloys, resulting from the smelting process and originating in the copper ores (which are sulphidic and closely associated with sphalerite). Arsenic is detected in 25 artefacts, in a concentration of 0.2%. The limited amount of arsenic in only a few of the artefacts under study may be the result of the use of polymetallic ores from the area of Limassol Forest, the only Cypriot ores where low amounts of arsenic can be detected, or can be interpreted as evidence for the possible use of recycled metal deriving from artefacts dating to the Early and Middle Bronze Age. The present study provides significant evidence concerning the continuity of the use of bronze with high tin content in the area of Palaepaphos throughout the Early Iron Age.",
Arsenic,1034394,"The absorption of arsenic into single human head hairs Abstract: Single head hairs from several subjects have been soaked in arsenic radiotracer solution and the arsenic absorbed on 2-mm hair segments has been determined by radioactivity assay. The absorption patterns were characterized for some subjects by regions of high uptake where (in other hairs from the same subject) regions of low uptake of copper and zinc were found, and vice versa. These data have been interpreted in terms of varying densities of binding sites in the hair structure, with specific chemical character. Arsenic absorption patterns for other subjects were highly structured, showing zones of very high and very low absorption. The dangers of interpreting similar patterns for the indigenous arsenic content of hair in terms of the dates on which elevated arsenic ingestion took place have been discussed.",
Arsenic,1018439,"Involvement of calcium-dependent protein kinase C in arsenite-induced genotoxicity in Chinese hamster ovary cells Abstract: Arsenic is the first metal to be identified as a human carcinogen. Arsenite, one inorganic form of arsenic, has been found to induce sister chromatid exchange, chromosome aberrations, and gene amplification in a variety of in vitro systems. In this study of arsenite-induced genotoxicity represented a micronuclei production in Chinese hamster ovary cells (CHO-K1), we found that the calcium channel blocker, verapamil, can potentiate arsenite-induced micronuclei. And after arsenite treatment, the elevation of intracellular calcium was observed. When extracellular calcium was depleted during arsenite treatment, the arsenite-induced micronuclei formation was significantly suppressed. These data indicated that a calcium ion plays an essential role in arsenite-induced genotoxicity. Further, it was found that the cotreatment of arsenite and a calcium ionophore, A23187, can increase the micronuclei induction. In contrast, pretreatment of the intracellular calcium chelator, quin 2, significantly inhibited micronuclei production of arsenite administration. In addition, we measured the activity of calcium- and phospholipid-dependent protein kinase C (PKC) and found that arsenite can activate PKC activity in a dose-dependent manner. Subsequently, some PKC activators and inhibitors were applied to investigate the involvement of PKC on arsenite-induced micronuclei formation. It was found that H7, a PKC inhibitor, can depress but TPA, a PKC activator, can enhance arsenite-induced micronuclei significantly. These data indicated that arsenite exposure perturbs intracellular calcium homeostasis and activates PKC activity. As a result, the activation of PKC activity may play an important role in arsenite-induced genotoxicity.",
Arsenic,1015847,"Arsenic biomethylation by photosynthetic organisms Abstract: Arsenic (As) is a ubiquitous element that is widespread in the environment and causes numerous health problems. Biomethylation of As has implications for its mobility and toxicity. Photosynthetic organisms may play a significant role in As geochemical cycling by methylating it to different As species, but little is known about the mechanisms of methylation. Methylated As species have been found in many photosynthetic organisms, and several arsenite S-adenosylmethionine (SAM) methyltransferases have been characterized in cyanobacteria and algae. However, higher plants may not have the ability to methylate As. Instead, methylated arsenicals in plants probably originate from microorganisms in soils and the rhizosphere. Here, we propose possible approaches for developing 'smart' photosynthetic organisms with an enhanced and sensitive biomethylation capacity for bioremediation and safer food.",
Arsenic,710983,"Lung function in adults following in utero and childhood exposure to arsenic in drinking water: Preliminary findings Abstract: PURPOSE: Evidence suggests that arsenic in drinking water causes non-malignant lung disease, but nearly all data concern exposed adults. The desert city of Antofagasta (population 257,976) in northern Chile had high concentrations of arsenic in drinking water (>800 ?g/l) from 1958 until 1970, when a new treatment plant was installed. This scenario, with its large population, distinct period of high exposure, and accurate data on past exposure, is virtually unprecedented in environmental epidemiology. We conducted a pilot study on early-life arsenic exposure and long-term lung function. We present these preliminary findings because of the magnitude of the effects observed. METHODS: We recruited a convenience sample consisting primarily of nursing school employees in Antofagasta and Arica, a city with low drinking water arsenic. Lung function and respiratory symptoms in 32 adults exposed to >800 ?g/l arsenic before age 10 were compared to 65 adults without high early-life exposure. RESULTS: Early-life arsenic exposure was associated with 11.5% lower forced expiratory volume in 1 s (FEV(1)) (P = 0.04), 12.2% lower forced vital capacity (FVC) (P = 0.04), and increased breathlessness (prevalence odds ratio = 5.94, 95% confidence interval 1.36-26.0). Exposure-response relationships between early-life arsenic concentration and adult FEV(1) and FVC were also identified (P trend = 0.03). CONCLUSIONS: Early-life exposure to arsenic in drinking water may have irreversible respiratory effects of a magnitude similar to smoking throughout adulthood. Given the small study size and non-random recruitment methods, further research is needed to confirm these findings.",
Arsenic,2278430,"Trace metal leaching from embankment soils amended with high-carbon fly ash Abstract: The use of fly ash in highway applications as a stabilizing agent and soil amendment for embankments has become very common owing to its economical advantages. However, fly ash may contain toxic constituents that may pose environmental risk if they leach through the soil and reach groundwater. A series of water leach tests (WLTs), toxicity characteristic leaching procedure (TCLP) tests, and column leach tests (CLTs) were conducted to define the leaching of aluminum, arsenic, chromium, and zinc from a self-cementitious fly ash and four different off-spec high-carbon ashes. Laboratory results indicated that an increase in fly ash contents generally yields an increase in pH and leached metal concentrations regardless of the type of fly ash and metals. Furthermore, it was determined that there were significant differences in the leached metal concentrations measured in the three different laboratory tests, i.e., CCLT>CTCLP>CWLT. Analyses conducted using a numerical groundwater model indicated that predicted field metal concentrations for the mixtures prepared with high-carbon fly ash were generally lower than the concentrations measured in the laboratory and decreased to concentration levels that do not possess any environmental risk.",
Arsenic,1015734,"Members of rice plasma membrane intrinsic proteins subfamily are involved in arsenite permeability and tolerance in plants Abstract: Rice accumulates high level of arsenic (As) in its edible parts and thus plays an important role in the transfer of As into the food chain. However, the mechanisms of As uptake and its detoxification in rice are not well understood. Recently, members of the Nodulin 26-like intrinsic protein (NIP) subfamily of plant aquaporins were shown to transport arsenite in rice and Arabidopsis. Here we report that members of the rice plasma membrane intrinsic protein (PIP) subfamily are also involved in As tolerance and transport. Based on the homology search with the mammalian AQP9 and yeast Fps1 arsenite transporters, we identified and cloned five rice PIP gene subfamily members. qRT-PCR analysis of PIPs in rice root and shoot tissues revealed a significant down regulation of transcripts encoding OsPIP1;2, OsPIP1;3, OsPIP2;4, OsPIP2;6, and OsPIP2;7 in response to arsenite treatment. Heterologous expression of OsPIP2;4, OsPIP2;6, and OsPIP2;7 in Xenopus laevis oocytes significantly increased the uptake of arsenite. Overexpression of OsPIP2;4, OsPIP2;6, and OsPIP2;7 in Arabidopsis yielded enhanced arsenite tolerance and higher biomass accumulation. Further, these transgenic plants showed no significant accumulation of As in shoot and root tissues in long term uptake assays. Whereas, short duration exposure to arsenite caused both active influx and efflux of As in the roots. The data suggests a bidirectional arsenite permeability of rice PIPs in plants. These rice PIPs genes will be highly useful for engineering important food and biofuel crops for enhanced crop productivity on contaminated soils without increasing the accumulation of toxic As in the biomass or edible tissues.",
Arsenic,2347574,"Arsenite oxidation by a facultative chemolithoautotrophic Sinorhizobium sp. KGO-5 isolated from arsenic-contaminated soil Abstract: A chemolithoautotrophic arsenite-oxidizing bacterium, designated strain KGO-5, was isolated from arsenic-contaminated industrial soil. Strain KGO-5 was phylogenetically closely related with Sinorhizobium meliloti with 16S rRNA gene similarity of more than 99%, and oxidized 5?mM arsenite under autotrophic condition within 60?h with a doubling time of 3.0?h. Additions of 0.01-0.1% yeast extract enhanced the growth significantly, and the strain still oxidized arsenite efficiently with much lower doubling times of approximately 1.0?h. Arsenite-oxidizing capacities (11.2-54.1??mol?h(-1)?mg dry cells(-1)) as well as arsenite oxidase (Aio) activities (1.76-10.0?mU?mg protein(-1)) were found in the cells grown with arsenite, but neither could be detected in the cells grown without arsenite. Strain KGO-5 possessed putative aioA gene, which is closely related with AioA of Ensifer adhaerens. These results suggest that strain KGO-5 is a facultative chemolithoautotrophic arsenite oxidizer, and its Aio is induced by arsenic.",
Arsenic,1021689,"Dose-response relationship between arsenic exposure and the serum enzymes for liver function tests in the individuals exposed to arsenic: A cross sectional study in Bangladesh Abstract: <strong>BACKGROUND: </strong>Chronic arsenic exposure has been shown to cause liver damage. However, serum hepatic enzyme activity as recognized on liver function tests (LFTs) showing a dose-response relationship with arsenic exposure has not yet been clearly documented. The aim of our study was to investigate the dose-response relationship between arsenic exposure and major serum enzyme marker activity associated with LFTs in the population living in arsenic-endemic areas in Bangladesh.<br /><br /><strong>METHODS: </strong>A total of 200 residents living in arsenic-endemic areas in Bangladesh were selected as study subjects. Arsenic concentrations in the drinking water, hair and nails were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The study subjects were stratified into quartile groups as follows, based on concentrations of arsenic in the drinking water, as well as in subjects' hair and nails: lowest, low, medium and high. The serum hepatic enzyme activities of alkaline phosphatase (ALP), aspartate transaminase (AST) and alanine transaminase (ALT) were then assayed.<br /><br /><strong>RESULTS: </strong>Arsenic concentrations in the subjects' hair and nails were positively correlated with arsenic levels in the drinking water. As regards the exposure-response relationship with arsenic in the drinking water, the respective activities of ALP, AST and ALT were found to be significantly increased in the high-exposure groups compared to the lowest-exposure groups before and after adjustments were made for different covariates. With internal exposure markers (arsenic in hair and nails), the ALP, AST and ALT activity profiles assumed a similar shape of dose-response relationship, with very few differences seen in the higher groups compared to the lowest group, most likely due to the temporalities of exposure metrics.<br /><br /><strong>CONCLUSIONS: </strong>The present study demonstrated that arsenic concentrations in the drinking water were strongly correlated with arsenic concentrations in the subjects' hair and nails. Further, this study revealed a novel exposure- and dose- response relationship between arsenic exposure metrics and serum hepatic enzyme activity. Elevated serum hepatic enzyme activities in the higher exposure gradients provided new insights into arsenic-induced liver toxicity that might be helpful for the early prognosis of arsenic-induced liver diseases.",
Arsenic,734952,"Arsenic-induced decreases in the vascular matrix Abstract: Chronic ingestion of arsenic is associated with increased incidence of respiratory and cardiovascular diseases. To investigate the role of arsenic in early events in vascular pathology, C57BL/6 mice ingested drinking water with or without 50 ppb sodium arsenite (AsIII) for four, five, or eight weeks. At five and eight weeks, RNA from the lungs of control and AsIII-exposed animals was processed for microarray. Sixty-five genes were significantly and differentially expressed. Differential expression of extracellular matrix (ECM) gene transcripts was particularly compelling, as 91% of genes in this category, including elastin and collagen, were significantly decreased. In additional experiments, real-time RT-PCR showed an AsIII-induced decrease in many of these ECM gene transcripts in the heart and NIH3T3 fibroblast cells. Histological stains for collagen and elastin show a distinct disruption in the ECM surrounding small arteries in the heart and lung of AsIII-exposed mice. Immunohistochemical detection of alpha-smooth muscle actin in blood vessel walls was decreased in the AsIII-exposed animals. These data reveal a functional link between AsIII exposure and disruption in the vascular ECM. These AsIII-induced early pathological events may predispose humans to respiratory and cardiovascular diseases linked to chronic low-dose AsIII exposure.",
Arsenic,1508701,"Arsenic in marine sediments from French Mediterranean ports: Geochemical partitioning, bioavailability and ecotoxicology Abstract: This work investigates arsenic mobility, bioavailability and toxicity in marine port sediments using chemical sequential extraction and laboratory toxicity tests. Sediment samples were collected from two different Mediterranean ports, one highly polluted with arsenic and other inorganic and organic pollutants (Estaque port (EST)), and the other one, less polluted, with a low arsenic content (Saint Mandrier port (SM)). Arsenic distribution in the solid phase was studied using a sequential extraction procedure specifically developed for appraising arsenic mobility in sediments. Toxicity assessment was performed on sediment elutriates, solid phases and aqueous arsenic species as single substance using the embryo-toxicity test on oyster larvae (Crassostrea gigas) and the Microtox test with Vibrio fischeri. Toxicity results showed that all sediment samples presented acute and sub-chronic toxic effects on oyster larvae and bacteria, respectively. The Microtox solid phase test allow to discriminate As-contaminated samples from the less contaminated ones, suggesting that toxicity of whole sediment samples is related to arsenic content. Toxicity of dissolved arsenic species as single substance showed that Vibrio fischeri and oyster larvae are most sensitive to As(V) than As(III). The distribution coefficient (Kd) of arsenic in sediment samples was estimated using results obtained in chemical sequential extractions. The Kd value is greater in SM (450Lkg(-1)) than in EST (55Lkg(-1)), indicating that arsenic availability is higher for the most toxic sediment sample (Estaque port). This study demonstrates that arsenic speciation play an important role on arsenic mobility and its bioavailability in marine port sediments.",
Arsenic,627489,"Differential expression of molecular markers in arsenic- and non-arsenic-related urothelial cancer Abstract: Background: Little is known about the mechanisms of arsenic-related urothelial cancer (AsUC). The aim of this study was to reveal the differential expression of molecular markers between AsUC and non-arsenic-related UC (non-AsUC). Materials and Methods: Tissues of AsUC (n=33), non-AsUC (n=20) and normal bladder urothelia from patients with benign diseases (n=4) were examined for multiple selected molecular markers responsible for various cellular functions, includingglutathione, GST-pi, Bcl-2, p53 and c-Fos. Results: The mean cellular glutathione content of normal mucosal samples (33.4 +/- 7.2 microM/mg protein) was significantly higher than either non-AsUC (22.8 +/- 1.8, p = 0.04) or AsUC (16.4 +/- 1.6, p = 0.002). The glutathione content of non-AsUC was higher than that of AsUC (p = 0.012). The expressions of Bcl-2 and c-Fos in AsUC were significantly higher than those in non-AsUC (p = 0.004 and p = 0.02, respectively). Conclusion: The carcinogenic pathway for AsUC is different, in part, from that of non-AsUC. Cellular glutathione contents may be down-regulated during urothelial carcinogenesis. Bcl-2 and c-Fos may play important roles in arsenic-mediated carcinogenesis of the urothelium.",
Arsenic,1032199,"Arsenic and cadmium exposure in children living near a smelter complex in San Luis Potosí, Mexico Abstract: The main purpose of this study was to assess environmental contamination by arsenic and cadmium in a smelter community (San Luis Potosí City, México) and its possible contribution to an increased body burden of these elements in children. Arsenic and cadmium were found in the environment (air, soil, and household dust, and tap water) as well as in the urine and hair from children. The study was undertaken in three zones: Morales, an urban area close to the smelter complex; Graciano, an urban area 7 km away from the complex; and Mexquitic, a small rural town 25 km away. The environmental study showed that Morales is the most contaminated of the zones studied. The range of arsenic levels in soil (117-1396 ppm), dust (515-2625 ppm), and air (0.13-1.45 micrograms/m3) in the exposed area (Morales) was higher than those in the control areas. Cadmium concentrations were also higher in Morales. Estimates of the arsenic ingestion rate in Morales (1.0-19.8 micrograms/kg/day) were equal to or higher than the reference dose of 1 microgram/kg/day calculated by the Environmental Protection Agency. The range of arsenic levels in urine (69-594 micrograms/g creatinine) and hair (1.4-57.3 micrograms/g) and that of cadmium in hair (0.25-3.5 micrograms/g) indicated that environmental exposure has resulted in an increased body burden of these elements in children, suggesting that children living in Morales are at high risk of suffering adverse health effects if exposure continues.",
Arsenic,1936176,Procedia Earth and Plantetary Science In situ arsenic remediation complicated by carbonate Abstract: ,
Arsenic,1022199,"Effect of dietary co-administration of sodium selenite on sodium arsenite-induced ovarian and uterine disorders in mature albino rats Abstract: The subchronic treatment of mature female Wistar-strain albino rats in diestrous phase with sodium arsenite at a dose of 0.4 ppm/100 g body weight/rat/day via drinking water for period of 28 days (seven estrous cycles) caused a significant reduction in the plasma levels of leutinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol along with a significant decrease in ovarian activities of delta five, 3 beta-hydroxysteroid dehydrogenase (Delta5,3beta-HSD), and 17 beta-hydroxysteroid dehydrogenase (17beta-HSD) followed by a reduction in ovarian and uterine peroxidase activities. A significant weight loss of the ovary and uterus was also observed after this treatment, along with a prolonged diestrous phase and a high accumulation of arsenic in the plasma and these organs. Moreover, sodium arsenite was also responsible for ovarian follicular and uterine cell degeneration characterized by a high number of regressing follicles and a reduction in the uterine luminal diameter, respectively, in comparison with the controls. A dietary supplementation of sodium selenite at the dose of 0.6 mg/100 g body weight/rat/day for a period of 28 days along with arsenic treatment minimized the gonadal weight loss significantly and increased the activities of the ovarian steroidogenic enzymes as well as the ovarian and uterine peroxidase at the control level. Selenium was also able to increase the plasma levels of LH, FSH, and estradiol toward the control level. Vaginal smears showed normal estrous cyclicity in sodium selenite-supplemented arsenic-treated rats along with lower arsenic levels in the plasma and gonadal tissue in comparison with arsenic-only-treated rats. Histological sections of ovary and uterine tissues in the control and experimental groups confirmed that sodium selenite supplementation was able to prevent arsenic-induced histopathological changes in the ovary and uterus. Plasma levels of norepinephrine and dopamine in the midbrain and diencephalon decreased significantly, whereas the serotonin level was increased significantly after 28 days of sodium arsenite treatment. All of these parameters were, in most cases, unchanged from the control level when sodium selenite was co-administered with sodium arsenite. Arsenic intoxication was also associated with increased liver weight and elevation in the activities of hepatic and renal acid phosphatase, alkaline phosphatase, and transaminases, but selenium co-administration was not able to change these toxic effects of arsenic. The results of our experiments indicate the significant protective action of sodium selenite on arsenic-induced toxicity in the female reproductive system, while there was no significant protective effect of selenium on arsenic-induced toxicity in other organs.",
Arsenic,1021583,"Automated method for the determination of total arsenic and selenium in natural and drinking water by HG-AAS Abstract: A multicommutated flow system was designed and evaluated for the determination of total arsenic and selenium by Hydride Generation Atomic Absorption Spectrometry (HG-AAS). It was applied to the determination of arsenic and selenium in samples of natural and drinking water. Detection limits were 0.46 and 0.08 ?g l(-1) for arsenic and selenium, respectively; sampling frequency was 120 samples h(-1) for arsenic and 160 samples h(-1) for selenium. Linear ranges found were 1.54-10 ?g l(-1) (R = 0.999) for arsenic and 0.27-27 ?g l(-1) (R = 0.999) for selenium. Accuracy was evaluated by spiking various water samples and using a reference material. Recoveries were in the range 95-116%. Analytical precision (s ( r ) (%), n = 10) was 6% for both elements. Compared with the Standard Methods, APHA, 3114B manual method, the system consumes at least 10 times less sample per determination, and the quantities of acid and reducing agent used are significantly lower with a reduction in the generation of pollutants and waste. As an additional advantage, the system is very fast, efficient and environmentally friendly for monitoring total arsenic and selenium levels in waters.",
Arsenic,1032022,"Concentrations and chemical species of arsenic in human urine and hair Abstract: The concentrations and chemical species of arsenic (7440382) in the human body were monitored by measurements on urine and hair. Urine samples were taken from 94 male and eight female students of a Japanese medical school. Hair samples were taken from 100 of the teaching staff of the medical school. Four species of arsenic were assayed by liquid nitrogen trapping arsine generation atomic absorptiometry. Mean concentrations of four arsenic compounds (micrograms arsenic per liter) in the urine samples after adjustment for differences in specific gravity were: inorganic, 11.9; methylarsonic-acid (124583) (MAA), 3.66; dimethylarsinic-acid (75605) (DMAA), 35.1; trimethylarsenic compounds, 70.5; and total arsenic, 121. Thus methylarsenic compounds made up about 90 percent of the arsenic in urine. The mean concentrations (micrograms arsenic per gram) in hair were inorganic 0.056; DMAA, 0.020; total arsenic 0.075. No MAA or TMA were detected in hair. It was noted that although man ingested large amounts of TMA from seafood (indicated by the TMA content of urine), no TMA was found in the hair, suggesting that it was rapidly eliminated from the body. The author concludes that inorganic arsenic detected in the urine derives from a portion of the dietary inorganic arsenic being excreted in unchanged form in the urine, and that the inorganic arsenic concentration in the urine of people on a normal diet is important when inorganic arsenic is used as an indicator for occupational exposure arsenic.",
Arsenic,1347047,"Role of health hazardous ethephone in nutritive values of selected pineapple, banana and tomato Abstract: ",
Arsenic,627125,"Co-mutagenic activity of arsenic and benzo[a]pyrene in mouse skin Abstract: Exposure to inorganic arsenic in drinking water is linked to skin, lung and bladder cancer in humans. The mechanism of arsenic-induced cancer is not clear, but exposure to arsenic and polycyclic arylhydrocarbons (PAH) is more carcinogenic than exposure to either type of carcinogen alone. Arsenic can also generate reactive oxygen species, suggesting that oxidation of DNA may play a role in carcinogenesis. Oxidization of guanosines in polyG tracts is known to cause frameshift mutations, and such events can be detected in situ using the G11 placental alkaline phosphatase (PLAP) transgenic mouse model, which reports frameshift mutations in a run of 11 G:C basepairs by generating cells containing heat-resistant alkaline phosphatase activity. PAH can also induce frameshift mutations. In the study described here, FVB/N mice carrying the G11 PLAP transgene were crossed to C57Bl/6 mice. Half of the hybrid mice were given drinking water with sodium arsenite (10 mg/L) for 10 weeks. Half of the arsenic treated mice were also exposed to benzo[a]pyrene (BaP) by skin painting (500 nmol/week) for 8 weeks. Another group of mice was exposed to BaP but not arsenic. The effect on frameshift mutation was assessed by staining sections of skin tissue to detect cells with PLAP activity. Arsenic alone had no significant effect. On average, mice given BaP alone had approximately three times more PLAP-positive (PLAP+) cells. By contrast, mice exposed to both arsenic and BaP exhibited 10-fold more PLAP+ cells in the skin, and these cells were often arranged in large clusters, suggesting derivation from stem cells. Whereas combined treatment produced more PLAP+ cells, stable BaP adduct levels and arsenic burdens were not higher in mice exposed to both agents compared to mice exposed to either one agent or the other.",
Arsenic,1936147,"Alishewanella sp strain GIDC-5, Arsenite hyper-tolerant bacteria isolated from industrial effluent of South Gujarat, India Abstract: ",
Arsenic,1337525,"Chronic Exposure of Renal Stem Cells to Inorganic Arsenic Induces a Cancer Phenotype Abstract: Inorganic arsenic in the drinking water is a multisite human carcinogen that potentially targets the kidney. Recent evidence also indicates that developmental arsenic exposure impacts renal carcinogenesis in humans and mice. Emerging theory indicates that cancer may be a disease of stem cells (SCs) and that there are abundant active SCs during early life. Therefore, we hypothesized that inorganic arsenic targets SCs, or partially differentiated progenitor cells (PCs), for oncogenic transformation. Thus, a rat kidney SC/PC cell line, RIMM-18, was chronically exposed to low-level arsenite (500 nM) for up to 28 weeks. Multiple markers of acquired cancer phenotype were assessed biweekly during arsenic exposure, including secreted matrix metalloproteinase (MMP) activity, proliferation rate, colony formation in soft agar, and cellular invasiveness. Arsenic exposure by 10 weeks and after also induced marked and sustained increases in colony formation, indicative of the loss of contact inhibition, and increased invasiveness, both cancer cell characteristics. Compared to the passage-matched control, chronic arsenic exposure caused exposure-duration dependent increases in secreted MMP-2 and MMP-9 activity, Cox-2 expression, and more rapid proliferation (all &gt;2-fold), characteristics typical of cancer cells. Dysregulation of SC maintenance genes and signaling pathways are common during oncogenesis. During arsenite exposure, expression of several genes associated with normal kidney development and SC regulation and differentiation (i.e., Wt-1, Wnt-4, Bmp-7, etc.) were aberrantly altered. Arsenic-exposed renal SCs produced more nonadherent spheroid bodies that grew much more aggressively in Matrigel, typical of cancer SCs (CSCs). The transformed cells also showed gene overexpression typical of renal SCs/CSCs (CD24, Osr1, Ncam) and arsenic adaptation such as overexpression of Mt-1, Mt2, Sod-1, and Abcc2. These data suggest that inorganic arsenic induced an acquired cancer phenotype in vitro in these rat kidney SCs potentially forming CSCs and, consistent with data in vivo, indicate that these multipotent SCs may be targets of arsenic during renal carcinogenesis.",
Arsenic,2149171,"Biomarkers of arsenic exposure and effects in a Canadian rural population exposed through groundwater consumption Abstract: Drinking water intake of arsenic (As) from private wells may represent a significant exposure pathway and induce oxidative DNA damage. We measured total As concentrations in hair and nails, and concentrations of the different species of As and its metabolites as well as 8-OHdG in urine of 110 non-smoking adults living in a rural region of the Province of Quebec, Canada. Significant differences in exposure biomarker levels were observed between individuals consuming drinking water with As levels of?1.0,>1.0 -?10 and>10??g/l. Multivariate linear regression analysis also showed a significant relationship between estimated daily drinking water intakes of As and biomarker levels. Conversely, 8-OHdG levels were not significantly related to daily drinking water intakes of As or to hair, nail or urinary exposure biomarker levels, according to multivariate linear regression analysis. Even at the relatively low levels of As found in well water of our participants, water consumption significantly increases their body load of As, as confirmed by multiple matrix measurements, which reflected exposure over different time frames. However, this increased internal As dose was not associated with higher oxidative damage to DNA as reflected by urinary 8-OHdG levels.Journal of Exposure Science and Environmental Epidemiology advance online publication, 6 November 2013; doi:10.1038/jes.2013.80.",
Arsenic,1337482,"Polymerization of silicate on hematite surfaces and its influence on arsenic sorption Abstract: Iron oxides and oxyhydroxides are important sorbents for arsenic in soils, sediments, and water treatment systems, but their long-term potential for arsenic retention may be diminished by the formation of polymeric silicate on their surfaces. To study these interactions, we first investigated the sorption of silicate to colloidal hematite (?-Fe2O3) in short-term (48 h) and long-term (210 days) batch experiments. The polymerization of silicate on the hematite surface was monitored by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The pH dependence of silicate sorption exhibited a maximum between pH 9.0 and 9.5. The condensation of silicate on hematite surfaces adsorbed from monomeric silicate solutions steadily continued over the 210 day period, whereby surface polymerization was slower at pH 3 than at pH 6. The effect of silicate surface polymerization on arsenate and arsenite sorption was studied by use of hematite pre-equilibrated with silicate for different time periods of up to 210 days. The competitive effect of silicate on arsenate and arsenite sorption increased with increasing silicate pre-equilibration time. Only under strongly acidic conditions (pH 3), where silicate sorption was weakest and surface polymerization was slowest, was arsenate and arsenite sorption not affected by the presence of silicate. We conclude that the long-term exposure to dissolved silicate can decrease the potential of natural iron (oxyhydr)oxides for adsorbing inorganic arsenic.",
Arsenic,2064207,"Desorption of arsenic from exhaust activated carbons used for water purification Abstract: This work aims to the analysis of arsenic desorption from an exhaust activated carbon used for the purification of a natural water. This last was used to mimic the properties of common groundwater or drinking water. Different low-cost and harmless eluting solutions were considered, including distilled water, natural water, saline (NaCl, CaCl2 and NaNO3) and basic (NaOH) solutions. Experimental results showed that, for 1g of activated carbon with arsenic loading close to the maximum value available for the model natural water (??0.1mg/g), it is possible to recover more than 80% of the arsenic using 20ml of 0.1M sodium chloride solution. A temperature variation within 20 and 40°C has scarce effect on desorption efficiency. A comparison between desorption data and adsorption isotherms data suggests that arsenic adsorption is actually a reversible process. Therefore, it is virtually possible to increase arsenic recovery efficiency close to 100% by increasing the NaCl concentration or the volume of the desorption solution, but a preliminary cost benefit analysis lead to consider a NaCl 0.1M solution as an optimal solution for practical applications.",
Arsenic,2278260,"Roles of miR-199a-5p and COX-2 in arsenic-induced tumor angiogenesis Abstract: Arsenic is a well-known human carcinogen which is closely associated with lung cancer. However, the mechanism underlying the arsenic-induced carcinogenesis remains to be elucidated. The alterations of miRNAs profiles in cancers have profound implication in cancer development. However, it remains to be determined whether the alterations of miRNA signature in response to carcinogens such as arsenic may result in cell malignant transformation and tumor growth. In this study, we developed an in vitro model by transforming human lung epithelial BEAS-2B cells through long-term exposure to low concentration of arsenic. The BEAS-2B cells were malignantly transformed validated by cell proliferation, anchorage independent growth and tumor growth assay. By utilizing this model, we found that miR-199a-5p expression level was dramatically repressed in arsenic-transformed cells. Re-expression of miR-199a-5p impaired arsenic-induced tumor angiogenesis through directly targeting hypoxia inducible factor-1? (HIF-1?). Interestingly, we found another proangiogenic factor cyclooxygenase-2 (COX-2) that was also upregulated in arsenic-transformed cells and was predicted as a target of miR-199a-5p. It was confirmed by generating COX-2 3’UTR miRNA luciferase reporters with wild-type or mutant binding sites with miR-199a-5p. Overexpression of miR-199a-5p inhibited COX-2 protein expression. Functional study revealed that knockdown of COX-2 by siRNA in arsenic-transformed cells decreased tumor angiogenesis. We further showed that the COX-2 promoter contains a functional hypoxia response element (HRE). HIF-1? regulated COX-2 expression at the transcriptional level via direct binding to the HRE (-576/-584) located within the COX-2 promoter. Thus, arsenic-induced COX-2 activation is mediated by repression of miR-199a-5p and activation of HIF-1. Moreover, prostaglandin E2 (PGE2), a product of COX-2 regulated HIF-1 expression in a positive-feedback manner. In addition, arsenic-transformed cells have high levels of reactive oxygen species (ROS) for activating COX-2 pathway. Taken together, our results demonstrate that arsenic-induced angiogenesis through miR-199a-5p repression and pro-inflammatory responses induced by ROS. Both pathways lead to activation of HIF-1/COX-2 pathway. These findings establish critical roles of miR-199a-5p and its downstream targets HIF-1/COX-2 in arsenic-induced tumor angiogenesis. As miR-199a-5p is generally downregulated, whereas COX-2 is overexpressed in human lung cancer tissues, they may be used as new therapeutic targets for lung cancer treatment in the future.",
Arsenic,736154,"Effect of insulin on arsenic toxicity in diabetic rats—liver function studies Abstract: Arsenic (iAs)-induced diabetic mellitus has been debated by several workers. However, role of insulin in iAs-induced diabetes is yet to be investigated. Present report suggests that iAs promotes insulin secretion in diabetic rats and inhibits hyperglycemia. Whereas, reverse effects were recorded after insulin treatment to diabetic and iAs-treated rats. These conditions affect accumulation of iAs in liver. It decreased in diabetic and iAs-treated rats but increased after insulin treatment. Reciprocal effects were observed on serum transaminases and total bilirubin. Nevertheless, activity of glucose-6-phosphatase in the liver was stimulated by insulin treatment to diabetic and arsenic-fed rats. These results suggest that manifestations of arsenic-induced diabetes mellitus are not modulated or reversed by insulin. Observations on liver function further suggest that iAs is less toxic in diabetic rats. This protective effect has been attributed to noninsulin-dependent carbohydrate regulatory mechanisms. Diabetes certainly alters the pharmacodynamics and pharmacokinetics of iAs in rat.",
Arsenic,1354090,"70 KDA HEAT-SHOCK COGNATE PROTEIN IS A TRANSFORMATION-ASSOCIATED ANTIGEN AND A POSSIBLE TARGET FOR THE HOSTS ANTITUMOR IMMUNITY Abstract: We previously investigated a novel heat-inducible transformation-associated cell surface Ag that is expressed on the activated H-ras oncogene-transformed rat fibrosarcoma W31, but not its parental nontransformed fibroblast WFB. This Ag was detected by mAb 067. Herein, we characterized the molecular nature of the Ag by using anti-heat shock protein (HSP) mAb. The accumulated data indicated that the cell surface expression of Ag was clearly enhanced by several stressors, such as TNF, L-azetidine-2-carboxylic acid, and sodium arsenite. The immunoprecipitate made with mAb 067 and W31 cell lysates reacted with anti-rat 70 kDa heat shock cognate (HSC) mAb, TG5E, indicating that 067-defined Ag may be a rat 70 kDa HSC. Because this Ag seemed to be one of the transformation-associated Ag of WFB, we further studied whether it could play an important role in the host's anti-tumor immunity. Peripheral T cells of rats primed with live BCG showed cytotoxicity to W31 but not to WFB. Because the possibility existed that HSP may interact with certain populations of T cells, we focused on the reactivity of CD4-CD8- double negative T (DNT) cells against 067-defined molecule. DNT cells from spleen and PBL of live BCG-primed rats showed the cytotoxicity against W31 cells. This cytotoxicity was completely blocked by mAb 067 and anti-CD3 mAb. However, it was not blocked by mAb R48B1 and 109, which detect the MHC class I nonpolymorphic determinant and a target molecule of the cytolysis by poly I:C-induced NK cells, respectively. Furthermore, brefeldin A was able to block the cytotoxicity against W31 targets by DNT cells, but not by NK cells. These data suggest that 70 kDa HSC may be a tumor Ag and may act as a presenting molecule perhaps complexed with cellular peptides to certain DNT cells.",
Arsenic,1018624,An insect model for assessing arsenic toxicity: arsenic elevated glutathione content in the Musca domestica and Trichoplusia ni Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE MUSCA-DOMESTICA TRICHOPLUSIA-NI OXIDATIVE STRESS,
Arsenic,1597302,"Efficacy and resistance of gemtuzumab ozogamicin for acute myeloid leukemia Abstract: Seventy to 80 % of patients with acute myeloid leukemia (AML) achieve complete remission following intensive chemotherapy, but more than 50 % of patients in remission subsequently relapse, which is often associated with clinical drug resistance. Therapy based on monoclonal antibodies (mAbs) has been developed to increase the selectivity of cytotoxic agents by conjugating them with a mAb. Gemtuzumab ozogamicin (GO) is a conjugate of a cytotoxic agent, a calicheamicin derivative, linked to a recombinant humanized mAb directed against the CD33 antigen, which is expressed on leukemia cells from more than 90 % of patients with AML. This conjugated mAb was introduced following promising results from phase I and II studies. However, the initial phase III study did not confirm the efficacy of GO in combination with conventional chemotherapies. Several subsequent phase III studies have shown the efficacy of GO in favorable and intermediate risk AML. Several resistance mechanisms against GO have been reported. Multidrug resistant (MDR) P-glycoprotein (P-gp), a trans-membrane glycoprotein that pumps out many anti-leukemic agents from cells, also affects GO. For this reasons, GO has been used in combination with MDR modifiers, such as cyclosporine, and in cases without P-gp. Several investigators have reported successful results of the use of GO in acute promyelocytic leukemia (APL). GO has also been described as effective in cases relapsed after treatment with all-trans retinoic acid (ATRA), arsenic acid and conventional chemotherapeutic agents. The efficacy of GO will be studied mainly in a favorable risk of AML, such as core binding factor leukemia and APL. In addition, suitable combinations with other chemotherapies and administration schedules should be discussed.",
Arsenic,1022516,"Gene expression patterns as potential molecular biomarkers for malignant transformation in human keratinocytes treated with MNNG, arsenic, or a metal mixture Abstract: In previous studies, treatment with 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) enhanced malignant transformation of immortal human epidermal (RHEK-1) keratinocytes. In contrast, arsenic (As) alone or in a mixture of As, cadmium (Cd), chromium (Cr), and lead (Pb) inhibited this process. Microarray analysis showed unique gene expression patterns in RHEK-1 exposed to MNNG, As, or the metal mixture. From this analysis, we have selected 16 genes potentially involved in the enhancement or inhibition of transformation. These 16 genes, nine (IFN inducible protein 9-27, MAA A32, CCLB protein, integrin beta4, XRCC1, K8, K18, MT3, MAPKK6) of which were altered in a chemical-specific manner and seven (MIC1, bikunin, MTS1, BMP4, RAD23A, DOC2, vimentin) of which were commonly affected by the MNNG and As or mixture treatments, were examined for expression in detail by real-time RT-PCR. Qualitatively, both microarray and real-time RT-PCR analyses gave comparable results for 15 of 16 genes, i.e., genes were consistently induced or suppressed under the different treatment regimens when measured by either technique. Of the seven genes altered in their expression by multiple chemical treatments, five showed patterns consistent with a role in the transformation process, i.e., they were oppositely regulated in MNNG-transformed RHEK-1 cells (designated as OM3) as compared to the nonmalignant As- and mixture-exposed cells. Through time-course studies, we also identified markers whose expression correlates with acquisition of transformation-associated characteristics in OM3. Identification of a battery of genes altered during progressive transformation of RHEK-1 should aid in developing a mechanistic understanding of this process, as well as strengthening the utility of these genes as biomarkers.",
Arsenic,75000,"Neurotoxic effects from residential exposure to chemicals from an oil reprocessing facility and superfund site Abstract: Neurotoxicity has been described in workers exposed to solvents, PCBs, certain metals, and polyaromatic hydrocarbons but not often in residents near refineries or factories. We compared the neurobehavioral performance of residents near a plant that reprocessed used motor oil and chemical waste from 1966?1983 to referents from beyond the plant's modeled air dispersal and water drainage zones. Neurophysiological and psychological tests, a Profile of Mood States (POMS) and a symptom questionnaire were administered to 131 subjects exposed at the site who were matched for age, sex, and ethnicity 2:1 with 66 unexposed subjects from 35 km away. Test scores were adjusted for a 1.4-year difference in educational attainment by coefficients from regression equations but not for income as the latter coefficients were not significant. Exposed subjects were significantly impaired for body balance (sway speed) and simple and two choice visual reaction time as compared to referents. Blink reflex latency (R-1) and eye closure speed were normal in both groups. Cognitive function in the exposed was impaired as measured by Culture Fair and by block design from the WAIS. Placing pegs in a grooved board and making of trails (A and B) were also impaired. Group differences in recall and memory were not significant. The exposed group's symptom frequencies and POMS scores for depression, anger, confusion, tension, and fatigue were elevated indicating depression. Confounding from medical and neurological disorders or occupational exposures was minimal. Subjects exposed residentially for up to 17 years to chemicals dispersed from a waste oil reprocessing plant showed neurophysiological and neuropsychological impairment.",
Arsenic,1326810,"The zinc finger transcription factor Egr-1 is upregulated in arsenite-treated human keratinocytes Abstract: Arsenite is a human carcinogen that may induce cancer in skin, liver, kidney, bladder or lung. Arsenite executes its toxic effects by the induction of signaling cascades. In particular, the activation of the stress-induced protein kinase c-Jun N-terminal protein kinase and p38 and the phosphorylation and activation of the transcription factor c-Jun have been linked to the biological effects of arsenite. We analyzed whether arsenite has an impact on the biosynthesis of the zinc finger transcription factor Egr-1. Egr-1 transcription is upregulated following treatment of cells with hormones, cytokines or toxic chemicals, and thus Egr-1 integrates many signaling cascades with changes in gene expression patterns. Here, we show by Western blot experiments that arsenite induces a transient synthesis of Egr-1 in human HaCaT keratinocytes. Egr-1 biosynthesis was activated by arsenite concentrations insufficient for the induction of c-Jun biosynthesis. This arsenite-triggered Egr-1 biosynthesis was completely inhibited by the mitogen-activated protein kinase kinase inhibitor PD98059 and by AG1487, an epidermal growth factor (EGF) receptor-specific tyrosine kinase inhibitor. These results indicate that activation of the EGF receptor as well as stimulation of the mitogen activated/extracellular signal-regulated protein kinase is essential for arsenite-induced upregulation of Egr-1. Moreover, we detected an elevated transcriptional activation potential of the ternary complex factor Elk1, a key transcriptional regulator of serum response element-driven gene transcription. The Egr-1 5'-flanking region contains five serum response elements. Accordingly, we observed an increase in Egr-1 promoter activity as a result of arsenite treatment. The fact that low concentrations of arsenite are sufficient to induce Egr-1 biosynthesis suggests that Egr-1 may be an integral part of arsenite-triggered signaling cascades leading to tumor formation or cell death via alterations of the cellular genetic program.",
Arsenic,1519174,"EFFECT OF ARSENIC ON GERMINATION, PHOTOSYNTHESIS AND GROWTH PARAMETERS OF TWO WINTER WHEAT VARIETIES IN IRAN Abstract: ",
Arsenic,1019776,"Decrease in bladder cell micronucleus prevalence after intervention to lower the concentration of arsenic in drinking water Abstract: Epidemiological studies performed in Taiwan, Argentina, and Chile suggest that ingestion of arsenic (As) may cause bladder cancer. Because of these findings, we previously investigated the relationship between As ingestion and genetic damage to the urothelium in two cross-sectional biomarker studies, one in Nevada and one in Chile. In both studies, we found that increased levels of micronucleated cells (MNCs) in exfoliated bladder cells were associated with elevated concentrations of As in drinking water, suggesting that As induces genetic damage to bladder cells. To further investigate this relationship, we conducted an intervention study in a subset of highly exposed men (n = 34) from the cross-sectional study in Chile. Subjects whose usual source of water contained about 600 micrograms/liter As were supplied with water lower in As (45 micrograms/liter) for 8 weeks, allowing ample opportunity for renewal and exfoliation of bladder epithelial cells. Mean urinary As levels decreased during the intervention from 742 to 225 micrograms/liter. Bladder MNC prevalence also decreased from 2.63 MNCs/1000 cells preintervention to 1.79 MNCs/1000 cells postintervention (P &lt; 0.05). When the analysis was limited to individuals previously having subcytotoxic urinary As levels (&lt; 700 micrograms/liter), the change between pre- and postintervention MNC was more pronounced: the level decreased from 3.54 to 1.47 MNCs/1000 cells, respectively (P = 0.002). Among smokers, MNC prevalences decreased from 4.45 MNCs/1000 cells preintervention to 1.44 MNCs/1000 cells postintervention (P = 0.002). Among nonsmokers, the decrease was much smaller: 2.04 MNCs/1000 cells preintervention to 1.90 MNCs/1000 cells postintervention (P = 0.25), suggesting that smoker's bladder cells could be more susceptible to genotoxic damage caused by As. The reduction in bladder MNC prevalence with reduction in As intake provides further evidence that As is genotoxic to bladder cells.",
Arsenic,1337672,"Polyamines inhibit the assembly of stress granules in normal intestinal epithelial cells regulating apoptosis Abstract: Polyamines regulate multiple signaling pathways and are implicated in many aspects of cellular functions, but the exact molecular processes governed by polyamines remain largely unknown. In response to environmental stress, repression of translation is associated with the assembly of stress granules (SGs) that contain a fraction of arrested mRNAs and are thought to function as mRNA storage. Here we show that polyamines modulate the assembly of SGs in normal intestinal epithelial cells (IECs) and that induced SGs following polyamine depletion are implicated in the protection of IECs against apoptosis. Increasing the levels of cellular polyamines by ectopic overexpression of the ornithine decarboxylase gene decreased cytoplasmic levels of SG-signature constituent proteins eukaryotic initiation factor 3b and T-cell intracellular antigen-1 (TIA-1)-related protein and repressed the assembly of SGs induced by exposure to arsenite-induced oxidative stress. In contrast, depletion of cellular polyamines by inhibiting ornithine decarboxylase with ?-difluoromethylornithine increased cytoplasmic eukaryotic initiation factor 3b and TIA-1 related protein abundance and enhanced arsenite-induced SG assembly. Polyamine-deficient cells also exhibited an increase in resistance to tumor necrosis factor-?/cycloheximide-induced apoptosis, which was prevented by inhibiting SG formation with silencing SG resident proteins Sort1 and TIA-1. These results indicate that the elevation of cellular polyamines represses the assembly of SGs in normal IECs and that increased SGs in polyamine-deficient cells are crucial for increased resistance to apoptosis.",
Arsenic,2278943,"GSTO1 uncommon genetic variants are associated with recurrent miscarriage risk Abstract: Objective: To explore the role of the GSTO1 gene in the pathogenesis of recurrent miscarriage (RM). Design: Genetic association study. Setting: Rome, Italy. Patient(s): 123 women with RM and 130 women without pregnancy complications. Intervention(s:) None. Main Outcome Measure(s:) Genotyping of two single nucleotide polymorphisms (A140D and E208K) and a 3-bp deletion (E155del) of the GSTO1 gene. Result(s): We found a statistically significant association between GSTO1*E208K variants and RM risk. Specifically, we identified this uncommon genetic variant only in women with RM. None of the women with physiologic pregnancies were carriers of K208 allele. Conclusion(s): GSTO1 has a role in detoxification metabolism, and we hypothesize that a functional variation of GSTO1 is a RM risk factor that interacts with environmental conditions.",
Arsenic,1247771,"Mechanisms Underlying the Inhibitory Effects of Arsenic Compounds on Protein Tyrosine Phosphatase (PTP) Abstract: Arsenic binding to biomolecules is considered one of the major toxic mechanisms, which may also be related to the carcinogenic risks of arsenic in humans. At the same time, arsenic is also known to activate the phosphorylation-dependent signaling pathways including the epidermal growth factor receptor, the mitogen-activated protein kinase and insulin/insulin-like growth factor-1 pathways. These signaling pathways originate at the level of receptor tyrosine kinases whose phosphorylation status is regulated by opposing protein tyrosine phosphatase (PTP) activity. Reversible tyrosine phosphorylation, which is governed by the balanced action of protein tyrosine kinases and phosphatases, regulates important signaling pathways that are involved in the control of cell proliferation, adhesion and migration. In the present study, we have focused on the interaction of cellular PTPs with toxic trivalent arsenite (iAs(III)) and its intermediate metabolites such as monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)) in vitro, and then determined the arsenic binding site in PTP by the use of recombinant PTPs (e.g., PTP1B and CD45). Interestingly, the activities of PTP1B (cytoplasm-form) or CD45 (receptor-linked form) were observed to be strongly inhibited by both methylated metabolites (i.e., MMA(III) and DMA(III)) but not by iAs(III). Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has clearly confirmed that the organic intermediate, DMA(III) directly bound to the active site cysteine residue of PTP1B (e.g., Cys215), resulting in inhibition of enzyme activity. These results suggest that arsenic exposure may disturb the cellular signaling pathways through PTP inactivation.",
Arsenic,1337372,"Sorption-bioavailability nexus of arsenic and cadmium in variable-charge soils Abstract: In this work, the nexus between sorption and bioavailability of arsenic (As) and cadmium (Cd) as affected by soil type, soil pH, ageing, and mobilizing agents were examined. The adsorption of As and Cd was examined using a number of allophanic and non-allophanic soils which vary in their charge components. The effect of pH and ageing on the bioavailability of As and Cd was examined using spiked soils in a plant growth experiment. The effect of phosphate (P)-induced mobility of As on its bioavailability was examined using a naturally contaminated sheep dip soil. The results indicated that the adsorption of both As and Cd varied amongst the soils, and the difference in Cd adsorption is attributed to the difference in surface charge. An increase in soil pH increased net negative charge by an average of 45.7mmol/kg/pH thereby increasing cation (Cd) adsorption; whereas, the effect of pH on anion (As) adsorption was inconsistent. The bioavailability of As and Cd decreased by 3.31- and 2.30-fold, respectively, with ageing which may be attributed to increased immobilization. Phosphate addition increased the mobility and bioavailability of As by 4.34- and 3.35-fold, respectively, in the sheep dip soil. However, the net effect of P on As phytoavailability depends on the extent of P-induced As mobilization in soils and P-induced competition for As uptake by roots. The results demonstrate the nexus between sorption and bioavailability of As and Cd in soils, indicating that the effects of various factors on bioavailability are mediated through their effects on sorption reactions.",
Arsenic,1372700,"Cellular metabolism of arsenic studied in mammalian cells in vitro Abstract: BIOSIS COPYRIGHT: BIOL ABS. The cytotoxicity of trivalent and pentavalent inorganic arsenic was studied in cultured mouse fibroblasts. Concentrations of As(III) in the muM range and approximately 10-fold higher concentrations of As(V) led to a reduction of cellular proliferation and viability with a concomitant increase of LDH release and stimulation of lactate production. Cells pretreated with a low As(III) concentration were less sensitive to toxic doses of As(III) or As(V). Uptake of As(III) by the cells was greater than that of As(V). Both forms of inorganic arsenic were converted intracellularly to monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which were subsequently released into the culture medium. In As- pretreated cells, which proved more resistant to As toxicity, biotransformation of inorganic to MMA and DMA was increased.",
Arsenic,2343484,"Readily available phosphorous and nitrogen counteract for arsenic uptake and distribution in wheat (Triticum aestivum L.) Abstract: Elevated arsenic content in food crops pose a serious human health risk. Apart from rice wheat being another main food crop is possibly cultivated on contaminated sites. But for wheat uptake mechanisms are not entirely understood especially with regard to nutrient fertilization and different moisture regimes taking into account heavy rainfall events due to climate change. Here we show that especially higher P-fertilization under changing redox conditions may enhance arsenic uptake. This counteracts with higher N-fertilization reducing arsenic transfer and translocation into aboveground plant parts for both higher P-fertilization and reducing soil conditions. Arsenic speciation did not change in grain but for leaves P-fertilization together with reducing conditions increased the As(V) content compared to other arsenic species. Our results indicate important dependencies of nutrient fertilization, moisture conditions and substrate type on As accumulation of wheat as one of the most important crop plants worldwide with implications for agricultural practices.",
Arsenic,526912,"Arsenic induces cell apoptosis in cultured osteoblasts through endoplasmic reticulum stress Abstract: Osteoporosis is characterized by low bone mass resulting from an imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Therefore, decreased bone formation by osteoblasts may lead to the development of osteoporosis, and rate of apoptosis is responsible for the regulation of bone formation. Arsenic (As) exists ubiquitously ill our environment and increases the risk of neurotoxicity, liver injury, peripheral vascular disease and cancer. However, the effect of As on apoptosis of osteoblasts is mostly unknown. Here, we found that As induced cell apoptosis in osteoblastic cell lines (including hFOB, MC3T3-E1 and MG-63) and mouse bone marrow stromal cells (M2-10B4). As also induced upregulation of Bax and Bak, downregulation of Bcl-2 and dysfunction of mitochondria in osteoblasts. As also triggered endoplasmic reticulum (ER) stress, as indicated by changes in cytosolic-calcium levels. We found that As increased the expression and activities Of glucose-regulated protein 78 (GRP78) and calpain. Transfection of cells with GRP78 or calpain siRNA reduced As-mediated cell apoptosis in osteoblasts. Therefore, our results suggest that As increased cell apoptosis in Cultured osteoblasts and increased the risk of osteoporosis. (C) 2009 Elsevier Inc. All Fights reserved.",
Arsenic,1346373,"Liver histopathology of the southern watersnake, Nerodia fasciata fasciata, following chronic exposure to trace element-contaminated prey from a coal ash disposal site Abstract: Previous studies have demonstrated the accumulation of arsenic, cadmium, selenium, strontium, and vanadium in livers of Southern Watersnakes fed fish from a coal-ash contaminated site. Our study is the first to investigate effects of trace element accumulation on cytology of snake liver. Snakes were born in the laboratory and raised for one or two years on diets consisting of varying proportions of contaminated fish. The majority (71%) of snakes fed contaminated prey did not exhibit any differences in liver histology when compared to control snakes fed an uncontaminated diet. In the remaining contaminant-exposed snakes, some aberrations were noted. The most prevalent pathology involved the proliferation of collagen fibers that resulted in narrowing or occlusion of sinusoids and increasing the mass of the intersinsuoidal parenychma. Fibrosis of the liver as a result of chronic injury has been reported previously in reptiles, but this is the first report that links such tissue damage to dietary contamination.",
Arsenic,1357249,"Hypersensitivity to Mitomycin C-Induced Chromatid Exchange as a Biomarker of Past Exposure to Arsenic Abstract: The possibility of using mitomycin-C (MMC) induced sister chromatid exchanges (SCEs) as an indicator of past arsenic (7440382) exposures was investigated. The cohort consisted of 66 persons with a history of occupational or environmental arsenic exposure living in a blackfoot (BF) disease endemic area of Taiwan. Ten had BF disease, 22 had cancer, eight had BF disease plus cancer, and 26 were healthy (internal controls). The external controls consisted of 23 healthy volunteers who did not live in the area and had not been occupationally exposed to arsenic. Blood samples were collected. The lymphocytes were harvested and scored for SCEs before and after treatment with 10 nanograms per milliliter MMC. The baseline SCE frequency in the BF plus cancer patients, BF disease patients, cancer patients, internal controls, and external controls were 10.06, 10.04, 9.84, 9.40, and 10.17 SCE/cell, respectively. The mean SCE frequency following MMC treatment in the BF plus cancer patients, BF disease patients, cancer patients, internal controls, and external controls was 15.56, 17.92, 17.83, 16.46, and 14.59 SCE/cell, respectively. Only the SCE frequency in the cancer patients and BF disease patients was significantly higher than in the external controls. The SCE frequency difference (DSCE), defined as the difference between the MMC induced and baseline SCE frequencies, in these groups was 7.05, 7.8, 7.99, 7.47, and 4.63SCE/cell, respectively. The DSCE frequencies in the cancer patients, BF disease patients, and internal controls were significantly higher than in the external controls. The baseline SCE frequency in smokers was significantly higher than in nonsmokers; however, the DSCE frequencies did not differ between smokers and nonsmokers. The authors conclude that the increased SCE response to MMC in the cohort may reflect hypersensitivity to carcinogens or mutagens. The similarity of baseline SCE and DSCE frequencies in BF disease and cancer patients and the internal controls suggests that this hypersensitivity may reflect previous arsenic exposure and not disease status.",
Arsenic,1354322,Slurry sampling for arsenic determination in Sediments by hydride generation atomic absorption Spectrometry Abstract: ,
Arsenic,1356837,"Chronic low dose AS(III) together with continuous high glucose results in a rosmediated stimulation of hyperglycemic stress markers in isolated endothelial cells Abstract: The incidence and severity of diabetic vascular complications has been shown to be increased in areas of high arsenic exposure. It has also been suggested that an intracellular excess of reactive oxygen species (ROS), superoxide anion in particular, forms the unifying mechanism in the formation of diabetic complications (Nature 404: 787 (2000)). Our hypothesis, extending from this, is that environmental levels of As(III) act together with high glucose to damage blood vessels through a ROS-mediated mechanism. In these first studies, human microvascular endothelial cells (HMEC-1) were exposed to high glucose (30 mM) plus or minus 0.1uM (75 ppb) As(III) for two weeks and markers of hyperglycemic stress measured. The addition of low-level As(III) to high glucose resulted in additive increases of the mitochondrial pro-apoptotic protein Bax, the pro-inflammatory protein ICAM-1, the inducible form of nitric oxide synthase iNOS, and the active forms of the cellular signaling proteins PKC-beta II and PKC-delta. In contrast, a lack of additive induction of poly (ADP) ribose (PAR), a product of the DNA damage-inducible protein PARP, was observed in response to these same stresses. Finally, the addition of 50 uM MnTBAP, a cell-permeable SOD-mimetic, reduced the induction of Bax, ICAM-1, PKC-beta II and PKC-delta in response to As(III) and high glucose. Ongoing work is to assess genome-wide changes in gene expression in response to chronic low dose As(III) and high glucose and future studies are to extend these findings to an animal model.",
Arsenic,1579389,"Arsenic and antimony determination in non- and biodegradable materials by hydride generation capacitively coupled plasma microtorch optical emission spectrometry Abstract: A sensitive method using a miniature analytical system with a capacitively coupled plasma microtorch (25W, 13.56MHz, 0.4lmin(-1) Ar) was developed and evaluated for the determination of As and Sb in recyclable plastics and biodegradable materials by hydride generation optical emission spectrometry. Given their toxicity, As and Sb should be subject to monitoring in such materials despite not being included within the scope of Restriction of Hazardous Substances Directive. The advantages of the proposed approach are better detection limits and lower analysis cost relative to conventional systems based on inductively coupled plasma optical emission and flame atomic absorption spectrometry with/without derivatization. Samples were subjected to acidic microwave-assisted digestion in a nitric-sulfuric acid mixture. Chemical hydride generation with 0.5% NaBH4 after the prereduction of As(V) and Sb(V) with 0.3% l-cysteine in 0.01moll(-1) HCl (10min contact time at 90±5°C) was used. Under the optimal hydride generation conditions and analytical system operation the detection limits (mgkg(-1)) were 0.5 (As) and 0.1 (Sb), whereas the precision was 0.4-7.1% for 10.2-46.2mgkg(-1) As and 0.4-3.2% for 7.1-156mgkg(-1) Sb. Analysis of two polyethylene CRMs revealed recoveries of 101±2% As and 100±1% Sb.",
Arsenic,1936043,"Infrared and Raman spectroscopic characterization of the arsenate mineral ceruleite Cu2Al7(AsO4)4(OH)13?11.5(H2O) Abstract: The molecular structure of the arsenate mineral ceruleite has been assessed using a combination of Raman and infrared spectroscopy. The most intense band observed at 903cm(-1) is assigned to the (AsO4)(3-) symmetric stretching vibrational mode. The infrared spectrum shows intense bands at 787, 827 and 886cm(-1), ascribed to the triply degenerate ?3 antisymmetric stretching vibration. Raman bands observed at 373, 400, 417 and 430cm(-1) are attributed to the ?2 vibrational mode. Three broad bands for ceruleite found at 3056, 3198 and 3384cm(-1) are assigned to water OH stretching bands. By using a Libowitzky empirical equation, hydrogen bond distances of 2.65 and 2.75Å are calculated. Vibrational spectra enable the molecular structure of the ceruleite mineral to be determined and whilst similarities exist in the spectral patterns with the roselite mineral group, sufficient differences exist to be able to determine the identification of the minerals.",
Arsenic,628743,"Contamination of groundwater and risk assessment for arsenic exposure in Ha Nam province, Vietnam Abstract: The characteristics of arsenic-contaminated groundwater and the potential risks from the groundwater were investigated. Arsenic contamination in groundwater was found in four villages (Vinh Tru, Bo De, Hoa Hau, Nhan Dao) in Ha Nam province in northern Vietnam. Since the groundwater had been used as one of the main drinking water sources in these regions, groundwater and hair samples were collected in the villages. The concentrations of arsenic in the three villages (Vinh Tru, Bo De, Hoa Hau) significantly exceeded the Vietnamese drinking water standard for arsenic (10 microg/L) with average concentrations of 348, 211, and 325 microg/L, respectively. According to the results of the arsenic speciation testing, the predominant arsenic species in the groundwater existed as arsenite [As(III)]. Elevated concentrations of iron, manganese, and ammonium were also found in the groundwater. Although more than 90% of the arsenic was removed by sand filtration systems used in this region, arsenic concentrations of most treated groundwater were still higher than the drinking water standard. A significant positive correlation was found between the arsenic concentrations in the treated groundwater and in female human hair. The risk assessment for arsenic through drinking water pathways shows both potential chronic and carcinogenic risks to the local community. More than 40% of the people consuming treated groundwater are at chronic risk for arsenic exposure.",
Arsenic,627993,"Brain regional responses in antioxidant system to ?-lipoic acid in arsenic intoxicated rat Abstract: Impaired antioxidant defense mechanisms and oxidative stress are implicated in the pathogenesis of arsenic toxicity. Our study was designed to determine whether alpha-lipoic acid, which has been shown to have substantial antioxidant properties, when administered (70 mg/kg body weight) once daily for 60 days along with arsenic (100 ppm sodium arsenite mixed in drinking water) would prevent arsenic-induced changes in antioxidant defense system, superoxide dismutase (SOD-total SOD, Mn SOD, Cu/Zn SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) in rat brain regions such as cortex, hypothalamus, striatum, cerebellum and hippocampus. The present study also examined the effect of alpha-lipoic acid over arsenic-induced oxidant production and lipid peroxidation level (LPO) in discrete brain regions of rats. The cortex, striatum and hippocampus showed greater decreases in GSH-Px enzyme activity than cerebellum and hypothalamus with arsenic exposure. Striatum had the greatest percentage of decreased activities of total SOD and Mn SOD, whereas cortex had the greatest percentage decrease in the activity of Cu/Zn SOD in arsenic-alone treated rats. Hypothalamus and cerebellum exhibited the lowest catalase activity among all tested regions in arsenic-only treated rats. Rate of dichlorofluorescin oxidation, an indication of reactive oxygen species and other intracellular oxidants production was increased with arsenic exposure in all brain regions studied. Cortex, hippocampus and striatum exhibited greater increase of LPO levels than cerebellum and hypothalamus. SOD, CAT, GSH-Px activities were upregulated in arsenic plus lipoic acid treated versus arsenic-only treated rats. Also, simultaneous lipoic acid treatment along with arsenic proved to be sufficient in reducing oxidant production and LPO level in all rat brain regions. Our results demonstrate that arsenic-induced deficits in antioxidant enzyme activities and increase in oxidant production and lipid peroxidation level in brain regions can be overcome through simultaneous treatment with lipoic acid.",
Arsenic,1597374,"Facile synthesis of mesoporous Ce-Fe bimetal oxide and its enhanced adsorption of arsenate from aqueous solutions Abstract: The mesoporous Ce-Fe bimetal oxide (MCFO) was synthesized through a soft-template method and first applied in the adsorption of arsenate in aqueous solutions. The synthesized MCFO was characterized with BET surface area, X-ray diffraction (XRD), zeta potential, scanning electron microscope (SEM), and Fourier transform infrared (FTIR) analysis. The mesoporous structure of the MCFO was determined according to the characterization result. The adsorption efficiency of arsenate ions on the MCFO was studied as a function of initial As(V) concentration, contact time, pH, and coexistent anions. It was found that the adsorption isotherms could be well described by Langmuir model, and the calculated maximum adsorption capacity of MCFO-1 for As(V) was 91.74 mg g(-1), which was significantly greater than that of ordinary Ce-Fe bimetal oxide (CFO). The results showed that the adsorption kinetic data obeyed the pseudo-second order model. Lower pH was favorable for As(V) adsorption on the MCFO. Coexistent phosphate ions exhibited an obvious interference on As(V) adsorption, followed by silicate and fluoride ions. The analysis of BET and FTIR indicated that the high efficiency of As(V) adsorption on this Ce-Fe bimetal oxide (MCFO) was closely related to its uniform mesoporous structure and abundant surface hydroxyl groups.",
Arsenic,1353490,"Local mining or lead importation in the Roman province of Africa Proconsularis? Lead isotope analysis of curse tablets from Roman Carthage, Tunisia Abstract: ",
Arsenic,2088544,"The mitochondrial F1FO-ATPase desensitization to oligomycin by tributyltin is due to thiol oxidation Abstract: The antibiotic oligomycin is known to inhibit mitochondrial F-type ATP synthases. The antibiotic inhibits both ATP synthesis and hydrolysis by blocking the H(+) translocation through FO which is coupled to the catalytic activity of F1. The amphiphilic organotin tri-n-butyltin (TBT), a known mitochondrial poison, can penetrate into biological membranes and covalently bind to electron-donor atoms of biomolecules such as sulfur. This study aims at exploring the mechanism(s) involved in the enzyme desensitization to oligomycin which occurs at concentrations &gt;1 ?M TBT. This poorly known effect of TBT, which only appeared at temperatures above the break in the Arrhenius plot of the enzyme activity, was found to be accompanied by the oxidation of isolated thiol groups of the mitochondrial complex. The oligomycin sensitivity was restored by the reducing agents glutathione and dithioerythritol and not influenced by antioxidants. The whole of data is consistent with the hypothesis that thiol oxidation is caused by TBT covalent binding to cysteine residues in a low-affinity site on FO and not by other possible oxidative events. According to this putative model, the onset of tin-sulfur bonds would trigger conformational changes and weaken the oligomycin interaction with FO.",
Arsenic,1355949,"The protective role of NF-kappaB and AP-1 in arsenite-induced apoptosis in aortic endothelial cells Abstract: Arsenite (NaAsO(2)) has been shown to produce vascular dysfunction in many studies. Arsenite-induced damage to vascular endothelial cells represents one of the possible mechanisms causing leakage of the vascular endothelial barrier. To explore arsenite-induced vascular endothelial damage, we used primary porcine aortic endothelial cells (PAECs) as an in vitro system to test the effects of arsenite on signal transduction pathways and apoptosis. Here we demonstrated that arsenite exposure induced apoptosis accompanied by the occurrence of apoptotic signals including degradation of poly(ADP-ribose) polymerase (PARP) and CPP32 (cleavage/activation) and DNA ladder formation. By using the luciferase reporter assay, we demonstrated that arsenite exposure differentially activated two redox-sensitive transcription factors, NF-kappaB and AP-1. Lower levels of arsenite exposure (25 microM NaAsO(2), 24 h) induced co-activation of NF-kappaB and AP-1, accompanied by 9% total apoptosis. In contrast, higher levels of arsenite exposure (40 microM NaAsO(2), 24 h) induced higher levels of AP-1 activation, accompanied by 45% total apoptosis. Blockade of NF-kappaB or JNK activity further enhanced arsenite-induced apoptosis. Upregulation of JNK activity showed no effect on arsenite-induced apoptosis. Based on these data, we propose that activation of redox-sensitive transcription factors, NF-kappaB and AP-1, plays a very important role in the protection of PAECs from arsenite-induced apoptosis.",
Arsenic,1378716,DETERMINATION OF SELENIUM AND ARSENIC IN MINERAL WATERS WITH HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE MAGNESIUM SODIUM SULFATE SELENIUM ARSENIC DRINKING WATER HYDRIDE GENERATION ELECTROTHERMAL SPECTROMETRY ANALYTICAL METHOD,
Arsenic,628519,"Glutathione modulates recombinant rat arsenic (+3 oxidation state) methyltransferase-catalyzed formation of trimethylarsine oxide and trimethylarsine Abstract: Humans and other species enzymatically convert inorganic arsenic (iAs) into methylated metabolites. Although the major metabolites are mono- and dimethylated arsenicals, trimethylated arsenicals have been detected in urine following exposure to iAs. The AS3MT gene encodes an arsenic (+3 oxidation state) methyltransferase, which catalyzes both the oxidative methylation of trivalent arsenicals and the reduction of pentavalent arsenicals. In reaction mixtures containing recombinant rat AS3MT (rrAS3MT) and radiolabeled arsenite, mono- and dimethylated arsenicals and a third radiolabeled product can be resolved by thin-layer chromatography. Hydride generation atomic absorption spectrometry and electrospray ionization mass spectrometry identified the third reaction product as trimethylarsine oxide. The addition of glutathione to reaction mixtures containing radiolabeled arsenite and rrAS3MT increased the yield of methylated and dimethylated arsenicals but suppressed the formation of trimethylarsine oxide. Although a dimethylarsenic-glutathione complex was rapidly converted to trimethylarsine oxide, the addition of a molar excess of glutathione to dimethylarsenic suppressed the production of trimethylarsine oxide. The nonquantitative recovery of radioarsenic from reaction mixtures suggested that AS3MT catalyzed the formation of a volatile arsenical. This volatile species was identified as trimethylarsine. Thus, AS3MT catalyzes the formation of all products in a reaction sequence leading from an inorganic to a volatile methylated arsenical. The regulation of this pathway by intracellular glutathione may be an important determinant of the pattern and extent of formation of arsenicals.",
Arsenic,627525,"Dose-dependent effects on the disposition of monomethylarsonic acid and dimethylarsinic acid in the mouse after intravenous administration Abstract: The organic arsenicals monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) are the primary metabolites of inorganic arsenic, a known human carcinogen. The objective of this study was to examine if dose would affect the excretion and terminal tissue disposition of MMA and DMA in the mouse. 14C-MMA (4.84 and 484 mumol/kg) and -DMA (8.04 and 804 mumol/kg) were administered to female mice via the tail vein. The mice were placed in metabolism cages for collection of urine (1, 2, 4, 8, 12, and 24 h) and feces (24 h). The animals were then sacrificed at 24 h and tissues were removed and analyzed for radioactivity. The urine was also analyzed for parent compound and metabolites. Urinary excretion of MMA- and DMA-derived radioactivity predominated over fecal excretion. Dose did not affect the overall urinary excretion of both compounds. However, fecal excretion was significantly lower in the low-dose MMA-treated animals as opposed to in the high-dose group, whereas in the high-dose DMA-treated group excretion was lower than in the low-dose DMA group. The retention of radioactivity was low (< 2% of dose) and the distribution pattern similar for both compounds, with carcass > liver > kidney > lung. The concentration of radioactivity (% dose/g tissue) was greater in kidney than in liver, lung, and blood for both compounds. The distribution and concentration of MMA-derived radioactivity was significantly greater in the liver and lung of the high-dose group. The MMA-treated animals excreted predominantly MMA in urine and lower amounts of DMA (< 10% of the dose). The percentage excreted as DMA was significantly higher in the low-dose MMA group. In the urine of DMA-treated animals, an unstable metabolite and the parent compound were detected. Overall, it appears the dose of organic arsenical administered has a minimal effect on its excretion and terminal tissue disposition in the mouse. The rapid elimination and low retention of MMA and DMA explain in part their low acute toxicity.",
Arsenic,1023930,"Screening ecological risk assessment for the benthic community in the Venice lagoon (Italy) Abstract: According to the risk hypothesis: the sediment as source of potential risk for the benthic community, an Ecological Risk Assessment (ERA) based on the quotient method was undertaken. The exposure of the benthic community to different classes of pollutants (metals, chlorinated organic compounds and polynuclear aromatic hydrocarbons) was inferred by estimating the pollutant stocks in the top 15-cm sediment of the whole Venice lagoon, after application of geostatistic techniques. The risk was calculated by comparing the sediment exposure profiles with the ecotoxicological benchmarks for benthic organisms. Kriging based maps of the spatial distribution of the estimated risk for the benthic community over the whole lagoon were obtained. The highest risk, found in the areas nearest to the sources of contamination (e.g., the industrial district of Porto Marghera and the river mouths), was posed by mercury (40% of the sampling stations showed exposure levels higher than the Probable Effect Level), arsenic and nickel (75% of the sampling stations exceeded the Threshold Effect Level).",
Arsenic,1677590,"Carotid intima-media thickness and plasma asymmetric dimethylarginine in Mexican children exposed to inorganic arsenic Abstract: BACKGROUND: Arsenic exposure is a risk factor for atherosclerosis in adults, but there is little information on arsenic and early risk biomarkers for atherosclerosis in children. Carotid intima-media thickness (cIMT) is an indicator of subclinical atherosclerotic burden that has been associated with plasma asymmetric dimethylarginine (ADMA), a predictor of cardiovascular disease risk. OBJECTIVES: The aim of this study was to investigate associations of arsenic exposure with cIMT, ADMA, and endothelial adhesion molecules (soluble intercellular cell adhesion molecule-1, sICAM-1; soluble vascular cell adhesion molecule-1, sVCAM-1) in children who had been exposed to environmental inorganic arsenic (iAs). METHODS: A cross-sectional study was conducted in 199 children 3 to 14 years of age who were residents of Zimapan, México. cIMT was evaluated using ultrasonography; plasma lipid profiles were evaluated by standard methods, ADMA, sICAM-1, and sVCAM-1 were analyzed by ELISA; and the concentrations of total speciated arsenic (tAs) in urine were measured using HG-CT-AAS. RESULTS: In the multiple linear regression model for cIMT, tAs categories were positive associated with cIMT increase, the estimated cIMT diameter were greater in 35-70 and ?70ng/mL groups (0.035 mm and 0.058 mm per 1 ng/mL increase in urinary tAs, respectively), compared to the <35 ng/mL. In addition to tAs level, plasma ADMA was significant predictor of cIMT. In adjusted regression model for plasma ADMA, cIMT, %iAs, and plasma sVCAM-1 were significant predictors of ADMA levels (e.g., 0.419 ?mol/L increase in ADMA per 1mm increase in cIMT). CONCLUSIONS: Arsenic exposure and plasma ADMA levels were positively associated with cIMT in a population of Mexican children with environmental arsenic exposure through drinking water.",
Arsenic,1018986,"Arsenic induces DNA damage via reactive oxygen species in human cells Abstract: To elucidate arsenic-induced oxidative DNA damage, the genotoxicity of arsenic in human cells was comparatively studied with single cell gel electrophoresis (SCGE) assay in combination with the observation of the protective effects of dimethyl sulfoxide (DMSO) and catalase. Arsenic, at the concentration of 2.4 ?M by coincubation for 24 hours, significantly induced DNA damage in HL60, a human promyelocytic leukemia cell line. In contrast, significant DNA damage was found in human mononucleocytes at the concentration of 4.8 ?M or above. The cells were incubated separately with DMSO (12 mM/l), a well-known hydroxyl radical (OH(-)) scavenger, and catalase (1,300 U/ml), a hydrogen peroxide (H(2)O(2)) scavenger, for 6 hours and then further coincubated with various concentrations of arsenic for 24 hours at 37°C and 5% CO(2). The findings showed that both DMSO and catalase significantly reduced the arsenic-induced tail moment, a parameter of total damaged DNA, in HL60 and mononucleocytes. Hence our findings indicate that arsenic, with micromolar concentrations, induces typical and various extents of DNA damage in human cells via reactive oxygen species in a dose-dependent manner.",
Arsenic,2278020,"Adsorption/Oxidation of arsenic in groundwater by nanoscale Fe-Mn binary oxides loaded on zeolite Abstract: Nanoscale Fe-Mn binary oxides loaded on zeolite (NIMZ) is synthesized and characterized. The as-synthesized adsorbent is amorphous with 126 m2/g surface area; it is effective for the adsorption of both As(III) and As(V) in synthetic groundwater. It has high adsorption capacities of 296.23 and 201.10 mg/g for As(III) and As(V), respectively. For the adsorption of 2 mg/L arsenic, the aqueous concentration quickly decreases to less than 10 /microg/L within 30 min. During the adsorption of As(III), the in-aqueous measurement of As(V) shows a low concentration in the initial stage and disappears afterward. The fraction of As(V) on NIMZ gradually increases with time, proving the oxidation of As(III). The adsorption of As(III) and As(V) decreases with increasing pH. The anions of SiO3(2-), H2PO4(-), and HCO3(-) significantly compete with arsenic for the adsorption sites. The innersphere surface complexes are formed by As(III) or As(V) with the hydroxyl groups on the surface of NIMZ.",
Arsenic,1936200,"Effect of phosphorus on the concentrations of arsenic, iron and some other elements in barley grown hydroponically Abstract: ",
Arsenic,1024540,"Mechanism of selenium-induced inhibition of arsenic-enhanced UVR carcinogenesis in mice Abstract: <strong>BACKGROUND: </strong>Hairless mice that ingested arsenite in drinking water exhibited more than a 5-fold enhancement of ultraviolet radiation (UVR) carcinogenesis, whereas arsenite alone was carcinogenically inactive. Dietary organoselenium blocked the cancer enhancement effect of arsenic but not cancer induction by UVR.<br /><br /><strong>OBJECTIVE: </strong>In this study we sought to explain selenium blockage of As enhancement by establishing the extent that As and Se tissue distributions are coincident or divergent.<br /><br /><strong>METHODS: </strong>We used the X-ray fluorescence microprobe at the Advanced Photon Source (Argonne National Laboratory) to probe sections of skin and liver from hairless mice exposed to a) UVR, b) UVR + As, c) UVR + organoselenium, or d) UVR + As + organoselenium.<br /><br /><strong>RESULTS: </strong>We found elevated levels of As in the skin epithelium (hair follicles and epidermis) and diffusely in the liver of mice exposed to UVR + As. Arsenic was entirely absent in skin in mice exposed to UVR + As + organoselenium, but a diffuse low level was seen in the liver. As and Se locations were consistently divergent in skin; As was more diffusely distributed, whereas Se was strongly associated with membranes. X-ray absorption near-edge spectra are consistent with the presence of the seleno-bis(S-glutathionyl) arsinium ion in the liver.<br /><br /><strong>CONCLUSIONS: </strong>Supplemental Se was uncommonly effective at preventing even a trace of As in skin at 14 or 196 days of continuous exposure to As in drinking water. Traces of the seleno-bis(S-glutathionyl) arsinium ion in the liver suggested that formation of this compound was more likely to be responsible for the As-blocking effect of Se than was a mechanism based on antioxidation.",
Arsenic,1026018,"Evaluation of two new arsenic field test kits capable of detecting arsenic water concentrations close to 10 microg/L Abstract: Millions of people worldwide are exposed to arsenic-contaminated drinking water. Arsenic field test kits may offer a cost-effective approach for measuring these exposures in the field, although the accuracy of some kits used in the past has been poor. In this study, arsenic concentrations were measured in 136 water sources in western Nevada using two relatively new arsenic test kits and compared to laboratory measurements using atomic fluorescence spectroscopy (AFS). Spearman's rank correlation coefficients comparing the Quick Arsenic and Hach EZ kits to laboratory measurements were 0.96 (p &lt; 0.001) and 0.95 (p &lt; 0.001), respectively. When analyzed in seven exposure categories (0-9, 10-19, 20-49, 50-99, 100-199, 200-499, and &gt; or = 500 microg/L), test kit and AFS measurements were in the same category in 71% (Quick Arsenic) and 62% (Hach EZ) of samples, and within one category of each other in 99% (Quick Arsenic) and 97% (Hach EZ) of samples. Both kits identified all water samples with high arsenic concentrations (&gt; 15 microg/L) as being above the United States Environmental Protection Agency's drinking water standard and the World Health Organization's guideline value for arsenic of 10 microg/L. These results suggestthatthese easily portable kits can be used to identify water sources with high arsenic concentrations and may provide an important tool for arsenic surveillance and remediation programs.",
Arsenic,1030161,"Quantitative and morphological changes of Langerhans cells in Bowen's disease from patients with chronic arsenicism Abstract: Langerhans cells (LCs) are considered to be responsible for the immunologic presentation of tumor-associated antigens and play a role in the elimination of neoplastic clones. Ultraviolet light B can cause dysfunction and loss of LCs. Both the number and dendritic morphology of LCs are known to be diminished in squamous cell carcinomas from sun-exposed skin. The effects of arsenics on LCs are unknown. Using an OKT-6 monoclonal antibody to stain intraepithelial LCs, we compared their number and morphology in Bowen's lesions and in the perilesional skin from sun-protected sites in ten patients with chronic arsenicism. There was a significant reduction in the numbers of LCs in the Bowen's lesions as compared to the perilesional skin specimens. Loss of dendrites was observed in all Bowen's lesions and in seven of the perilesional skin specimens. Ultrastructurally, the LCs showed an absence of dendrites, but the Birbeck granules were preserved. Since the specimens were not from sun-exposed skin in our study, the findings may be related to chronic arsenic intoxication. The morphologic alteration of LCs observed in the perilesional skin further suggests an arsenic-related systemic dysfunction of the LCs, which in turn may contribute to the development of skin cancers in these patients.",
Arsenic,1347070,"In situ proteo-metabolomics reveals metabolite secretion by the acid mine drainage bio-indicator, Euglena mutabilis Abstract: Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited.",
Arsenic,627968,"Arsenic in drinking water and risk of urinary tract cancer: A follow-up study from northeastern Taiwan Abstract: The evidence linking arsenic in drinking water with increased urinary cancer risk comes from populations in relatively high exposure areas (>100 microg/L), whereas studies from lower exposure areas (<100 microg/L) reported inconsistent results. A previous study conducted in northeastern Taiwan, where residents were exposed to relatively lower concentrations, reported increased risk of urinary cancer in a dose-response way. Using the same cohort with longer follow-up, we conducted analysis to elucidate the relationship between ingested arsenic and urinary cancer in lower exposure groups and assessed the influence of duration, recency, and latency of drinking arsenic-containing well water. A total of 8,086 residents from northeastern Taiwan were followed for 12 years. Incident urinary cancer was ascertained through linkage with the national cancer registry. All analysis was done by Cox proportional hazards regression models. There were 45 incidences of urinary cancer and a monotonic increased risk of urinary cancer was found with increasing arsenic concentration (P < 0.001). For the highly exposed (>100 microg/L), the relative risks (RR) were >5-fold, whereas the risk was elevated but not significant for low exposure (<100 microg/L). Relative to the arsenic concentration <10 microg/L, those who drank well water with higher concentration from birth [RR, 3.69; 95% confidence interval (95% CI), 1.31-10.4], still drank at enrollment (RR, 3.50; 95% CI, 1.33-9.22), and drank for >50 years (RR, 4.12; 95% CI, 1.48-11.5) had a significantly increased risk of urinary cancer. When restricted to urothelial carcinoma, all risk estimates including concentration and characteristics of well water consumption were higher.",
Arsenic,734951,"Dimethylarsinic acid in drinking water changed the morphology of urinary bladder but not the expression of DNA repair genes of bladder transitional epithelium in F344 rats Abstract: Inorganic arsenic increases urinary bladder transitional cell carcinoma in humans. In F344 rats, dimethylarsinic acid (DMA[V]) increases transitional cell carcinoma. Arsenic-induced inhibition of DNA repair has been reported in cultured cell lines and in lymphocytes of arsenic-exposed humans, but it has not been studied in urinary bladder. Should inhibition of DNA damage repair in transitional epithelium occur, it may contribute to carcinogenesis or cocarcinogenesis. We investigated morphology and expression of DNA repair genes in F344 rat transitional cells following up to 100 ppm DMA(V) in drinking water for four weeks. Mitochondria were very sensitive to DMA(V), and swollen mitochondria appeared to be the main source of vacuoles in the transitional epithelium. Real-time reverse transcriptase polymerase chain reaction (Real-Time RT PCR) showed the mRNA levels of tested DNA repair genes, ataxia telangectasia mutant (ATM), X-ray repair cross-complementing group 1 (XRCC1), excision repair cross-complementing group 3/xeroderma pigmentosum B (ERCC3/XPB), and DNA polymerase beta (Polbeta), were not altered by DMA(V). These data suggested that either DMA(V) does not affect DNA repair in the bladder or DMA(V) affects DNA repair without affecting baseline mRNA levels of repair genes. The possibility remains that DMA(V) may lower damage-induced increases in repair gene expression or cause post-translational modification of repair enzymes.",
Arsenic,1017445,"Arsenic in surface soils affected by mining and metallurgical processing in K. Mitrovica region, Kosovo Abstract: The results of a study on the spatial distribution of arsenic in topsoil (0-5 cm) over the K. Mitrovica region, Kosovo, are reported. The investigated region (300 km(2)) was covered by a sampling grid of 1.4 km × 1.4 km. In total, 159 soil samples were collected from 149 locations. Inductively coupled plasma-mass spectrometry (ICP-MS) was applied for the determination of arsenic levels. It was found that the average content of arsenic in the topsoil for the entire study area was 30 mg/kg (from 2.1 to 3,900 mg/kg) which exceeds the estimated European arsenic average in topsoil by a factor of 4.3. Contents of arsenic in the topsoil exceeded the optimum value recommended by the new Dutchlist (29 mg/kg As) in 124 km(2). The action value (55 mg/kg As) was exceeded in 64 km(2), with the average content of 105 mg/kg (from 55 to 3,900 mg/kg As).",
Arsenic,1936040,"Organization and regulation of the arsenite oxidase operon of the moderately acidophilic and facultative chemoautotrophic Thiomonas arsenitoxydans Abstract: Thiomonas arsenitoxydans is an acidophilic and facultatively autotrophic bacterium that can grow by oxidizing arsenite to arsenate. A comparative genomic analysis showed that the T. arsenitoxydans aioBA cluster encoding the two subunits of arsenite oxidase is distinct from the other clusters, with two specific genes encoding a cytochrome c and a metalloregulator belonging to the ArsR/SmtB family. These genes are cotranscribed with aioBA, suggesting that these cytochromes c are involved in arsenite oxidation and that this operon is controlled by the metalloregulator. The growth of T. arsenitoxydans in the presence of thiosulfate and arsenite, or arsenate, is biphasic. Real-time PCR experiments showed that the operon is transcribed during the second growth phase in the presence of arsenite or arsenate, whereas antimonite had no effect. These results suggest that the expression of the aioBA operon of T. arsenitoxydans is regulated by the electron donor present in the medium, i.e., is induced in the presence of arsenic but is repressed by more energetic substrates. Our data indicate that the genetic organization and regulation of the aioBA operon of T. arsenitoxydans differ from those of the other arsenite oxidizers.",
Arsenic,1019599,"Using ecological data to estimate a regression model for individual data: The association between arsenic in drinking water and incidence of skin cancer Abstract: In ecologic studies, participants are studied by groups, and the exposure status of each group is usually represented by a single indicator, mostly the mean exposure. In this paper, we propose using multiple variables derived from dummy variables at the individual level to describe the exposure. An analysis of the association between arsenic in drinking water and skin cancer was used as an example. Well water arsenic levels and skin cancer incidence from 1980 to 1987 were assessed for 243 townships in Taiwan. We first analyzed the data using the mean arsenic concentration in each township as the only exposure variable. The second analysis used multiple variables to describe arsenic exposure; each variable denoted the percentage of wells with arsenic levels within a specific range in each township. Although the first approach did not identify associations between arsenic levels and skin cancer, the multiple-variable approach identifies a positive association at the highest arsenic exposure category (&gt;0.64 mg/L) in both men and women. Therefore, using multiple variables to describe an exposure in ecologic studies may facilitate a better description of the exposure status and thereby lead to more accurate risk assessment, especially when the dose-response relationship is not linear.",
Arsenic,628552,"Dose-response relation between arsenic concentration in well water and mortality from cancers and vascular diseases Abstract: Age-adjusted mortality rates were analyzed to examine the dose-response relation between ingested arsenic levels and risk of cancers and vascular diseases among residents in the endemic area of blackfoot disease, a unique peripheral vascular disease associated with long-term exposure to high-arsenic artesian well water and confined to the southwestern coast of Taiwan. The arsenic levels in well water determined in 1964-1966 were available in 42 villages of the study area, while mortality and population data during 1973-1986 were obtained from the local household registration offices and Taiwan Provincial Department of Health. Age-adjusted mortality rates from various cancers and vascular diseases by sex were calculated using the 1976 world population as the standard population. A significant dose-response relation was observed between arsenic levels in well water and cancers of the bladder, kidney, skin, and lung in both males and females, and cancers of the prostate and liver in males. However, there was no association for cancers of the nasopharynx, esophagus, stomach, colon, and uterine cervix, and for leukemia. Arsenic levels in well water were also associated with peripheral vascular diseases and cardiovascular diseases in a dose-response pattern, but not with cerebrovascular accidents. The dual effect of arsenic on carcinogenesis and arteriosclerosis and the interrelation between these two pathogenic mechanisms deserve more intensive study.",
Arsenic,1356892,"Gene Expression Changes Associated With Altered Growth And Differentiation In Benzo(A)Pyrene Or Arsenic Exposed Normal Human Epidermal Keratinocytes Abstract: Normal human epidermal keratinocytes (NHEK) have been chosen as an in vitro model for mechanistic studies into how altered regulation of differentiation may play a role in the transformation process in human cells. Our initial work demonstrated that two high priority skin carcinogens, arsenic and benzo[a]pyrene (BaP), inhibit terminal differentiation in NHEK in vitro. Arsenic (>2 ?m) also decreases proliferation in a manner suggestive of a G2 block. In contrast, BaP increases proliferation rates and induces rapid progression through the cell cycle, possibly by a shortened G2 phase. Differentiation is much more sensitive to chemically-mediated perturbations than is proliferation, indicating that the former process may be the initial target at environmentally prevalent concentrations. To identify molecular alterations that are responsible for the observed chemical-specific effects, microarray analysis was carried out on NHEK treated with BaP and arsenic. From this analysis, chemically altered genes were selected that are known to be involved in growth regulation (Ras, IL-1 alpha and beta, TGF ), differentiation (RA/INF-inducible protein, YY1-associated factor 2), RNA synthesis (tRNA exportin, RNA cyclase homolog), cell structure/adhesion (Cadherin 5, alpha-integrin binding protein), apoptosis (CASP8, programmed cell death 10), and chromatin structure/function (RAD50, REV1). Alterations in expression of these genes induced by arsenic and/or BaP are currently being examined using highly quantitative Real-Time RT-PCR. Through extensive time-course and dose-response studies, we will aim to clarify whether similar, highly central, pathways are disrupted by these diverse skin carcinogens or whether only chemical-specific effects are evident.",
Arsenic,1453808,"Mitigation of hepatotoxic effects of arsenic trioxide through omega-3 fatty acid in rats Abstract: Arsenic trioxide (As(2)O(3)) is an effective drug in the treatment of leukaemia and many solid tumours. In clinical trials, arsenic therapy is closely associated with hepatic toxicity. The present study was designed to investigate the efficacy of omega-3 fatty acid against As(2)O(3)-induced hepatotoxicity. A 4 mg/kg body weight (bw) of As(2)O(3) was orally administered to Wistar male rats for 45 days. Hepatotoxicity was evaluated by biochemical tests, antioxidant assays and histopathological examinations. Arsenic accumulation was found in the liver tissue of rats treated with As(2)O(3). Hepatoprotective efficacy of omega-3 fatty acid was analysed by the combination therapy with As(2)O(3). In vivo studies revealed a significant rise in lipid peroxidation with concomitant decline in reduced glutathione, glutathione-dependant antioxidant enzymes and antiperoxidative enzymes in the liver tissue of rats treated with arsenic. The supplementation of omega-3 fatty acid at a dose of 50 mg/kg bw with As(2)O(3) offers ameliorative effect against hepatocellular toxicity. Omega-3 fatty acid maintained hepatic marker enzymes, antioxidant enzymes and decreased lipid peroxidation. The combination treatment clearly reduced the hepatic structural abnormalities such as haemorrhage, necrosis and cholangiofibrosis in the rats treated with arsenic. This study concludes that the omega-3 fatty acid might be useful for the protection against As(2)O(3)-induced hepatotoxicity.",
Arsenic,734875,"Arsenic accumulation, elimination, and interaction with copper, zinc and manganese in liver and kidney of rats Abstract: The arsenic accumulation, distribution and influences on metallothionein-1 (MT-1) expression and other trace elements in various organs were examined in rats orally exposed to sodium arsenate (iAs(V)). Rats received a dose of 0, 1, 10 and 100ppm of iAs(V) in drinking water daily for 4- and 16-weeks. Arsenic seems to be distributed in all of the tissues, and was accumulated relatively higher in the spleen, lung and kidney compared to the liver, and much lower in skin and cerebrum. High dose of iAs(V)-exposure significantly increased the concentration of copper in the kidney, but did not influence other trace elements such as zinc and manganese in the liver. The mRNA expression of MT-1 was dose-dependently increased by iAs(V)-exposure in the liver whereas it was decreased in the kidney. These data indicate that arsenic is widely distributed and significantly accumulated in various organs and influences on other trace elements, and also modulates MT-1 expression in the liver and kidney.",
Arsenic,1337475,"Association of cord blood levels of lead, arsenic, and zinc with neurodevelopmental indicators in newborns: A birth cohort study in Chitwan Valley, Nepal Abstract: In this study, we aimed to investigate the association between in utero toxic (lead [Pb] and arsenic [As]) and essential element (zinc [Zn]) levels and neurodevelopmental indicators after birth in Chitwan Valley, Nepal. We conducted a hospital-based birth cohort study with 100 pregnant women in Chitwan, Nepal. We measured Pb, As, and Zn concentrations in cord blood. We assessed 100 infants at 1 day after birth, using the Brazelton neonatal behavioral assessment scale, third edition (NBAS III). Multivariate regression was performed to adjust for mother's age, parity, educational level, and body mass index (BMI); family income; and newborn's birth weight, gestational age, and age in hours at the time of NBAS III assessment. Among the 7 clusters of NBAS III, the motor cluster score was inversely associated with the cord blood levels of Pb (coefficient=-2.15, at 95% confidence interval [CI]=-4.27 to -0.03). The cord blood levels of As were inversely associated with the state regulation cluster score (coefficient=-6.71, at 95% CI=-12.17 to -1.24). The cord blood levels of Zn were not associated with NBAS III scores. The cord blood levels of Pb and As, but not Zn, showed significant inverse association with the neurodevelopment of newborns. These results suggest that high levels of Pb or As exposure during the prenatal period may induce retardation during in utero neurodevelopment.",
Arsenic,2149176,"Ogg1 genetic background determines the genotoxic potential of environmentally relevant arsenic exposures Abstract: Inorganic arsenic (i-As) is a well-established human carcinogen to which millions of people are exposed worldwide. It is generally accepted that the genotoxic effects of i-As after an acute exposure are partially linked to the i-As-induced production of reactive oxygen species, but it is necessary to better determine whether chronic sub-toxic i-As doses are able to induce biologically significant levels of oxidative DNA damage (ODD). To fill in this gap, we have tested the genotoxic and oxidative effects of environmentally relevant arsenic exposures using mouse embryonic fibroblast MEF mutant Ogg1 cells and their wild-type counterparts. Effects were examined by using the comet assay complemented with the use of FPG enzyme. Our findings indicate that MEF Ogg1-/- cells are more sensitive to arsenite-induced acute toxicity, genotoxicity and ODD. Long-term exposure to sub-toxic doses of arsenite generates a detectable increase in ODD and genotoxic DNA damage only in MEF Ogg1-deficient cells. Altogether, the data presented here point out the relevance of ODD and Ogg1 genetic background on the genotoxic risk of i-As at environmentally plausible doses. The persistent accumulation of DNA 8-OH-dG lesions in Ogg1-/- cells during the complete course of the exposure suggests a relevant role in arsenic-associated carcinogenic risk in turn.",
Arsenic,2298700,"Arsenic in groundwater of the Paraiba do Sul delta, Brazil: An atmospheric source? Abstract: High concentrations of arsenic (&gt;50?gL(-1)) have been detected for the first time in groundwater of the wave-dominated Paraiba do Sul delta, Brazil. The deltaic shallow groundwater aquifer is enriched in arsenic fixed by authigenic sulfides. A study of palynomorphs confirmed that aquifer sediments were formed in inter-dune lakes/swamps lately covered by eolian sands. The organic sediments of contemporaneous inter-dune lake/swamp contain very high concentration of As: up to 180mgkg(-1) and 163?gL(-1) in dry gyttja material and interstitial water, respectively. The As in recent lake/swamp sediments is retained by iron hydroxides in upper and probably by sulfides in lower layers. In the absence of connection of inter-dune lakes/swamps with fluvial currents, the atmospheric input of As could be considered as the principal source in sediments. The calculation demonstrates the possibility of high concentrations of As accumulation in sediments of inter-dune lakes/swamps from atmospheric precipitations within several centuries before they will be covered by eolian sands and turned into shallow aquifer. Considering the commonalities of wave-dominated delta formations, we can predict more prevalent As accumulation in delta plain groundwater.",
Arsenic,1508663,"Arsenic release from arsenopyrite weathering: Insights from sequential extraction and microscopic studies Abstract: At a former As mine site, arsenopyrite oxidation has resulted in formation of scorodite and As-bearing iron hydroxide, both in host rock and mine tailings. Electron microprobe analysis documents that arsenopyrite weathers along two pathways: one that involves formation of sulfur, and one that does not. In both pathways, arsenopyrite oxidizes to form scorodite, which dissolves incongruently to form As-bearing iron hydroxides. From a mass balance perspective, arsenopyrite oxidation to scorodite conserves As, but as scorodite dissolves incongruently to iron hydroxides, As is released to solution, resulting in elevated As concentrations in the headwater stream adjacent to the site. The As-bearing iron hydroxide is the dominant solid phase reservoir of As in mine tailings and stream sediment, as suggested by sequential extraction. This As-bearing iron hydroxide is stable under the aerobic and pH 4-6 conditions at the site; however, changes in biogeochemical conditions resulting from sediment burial or future remedial efforts, which could promote As release from this reservoir due to reductive dissolution, should be avoided.",
Arsenic,627975,"Fetal onset of aberrant gene expression relevant to pulmonary carcinogenesis in lung adenocarcinoma development induced by in utero arsenic exposure Abstract: Arsenic is a human pulmonary carcinogen. Our work indicates that in utero arsenic exposure in mice can induce or initiate lung cancer in female offspring. To define early molecular changes, pregnant C3H mice were given 85 ppm arsenic in drinking water from days 8 to 18 of gestation and expression of selected genes in the fetal lung or in lung tumors developing in adults was examined. Transplacental arsenic exposure increased estrogen receptor-alpha (ER-alpha) transcript and protein levels in the female fetal lung. An overexpression of various estrogen-regulated genes also occurred, including trefoil factor-3, anterior gradient-2, and the steroid metabolism genes 17-beta-hydroxysteroid dehydrogenase type 5 and aromatase. The insulin growth factor system, which can be influenced by ER and has been implicated in the pulmonary oncogenic process, was activated in fetal lung after gestational arsenic exposure. In utero arsenic exposure also induced overexpression of alpha-fetoprotein, epidermal growth factor receptor, L-myc, and metallothionein-1 in fetal lung, all of which are associated with lung cancer. Lung adenoma and adenocarcinoma from adult female mice exposed to arsenic in utero showed widespread, intense nuclear ER-alpha expression. In contrast, normal adult lung and diethylnitrosamine-induced lung adenocarcinoma showed little evidence of ER-alpha expression. Thus, transplacental arsenic exposure at a carcinogenic dose produced aberrant estrogen-linked pulmonary gene expression. ER-alpha activation was specifically associated with arsenic-induced lung adenocarcinoma and adenoma but not with nitrosamine-induced lung tumors. These data provide evidence that arsenic-induced aberrant ER signaling could disrupt early life stage genetic programing in the lung leading eventually to lung tumor formation much later in adulthood.",
Arsenic,1797813,"Project Energize: whole-region primary school nutrition and physical activity programme; evaluation of body size and fitness 5 years after the randomised controlled trial Abstract: Project Energize, a region-wide whole-school nutrition and physical activity programme, commenced as a randomised controlled trial (RCT) in the period 2004-6 in 124 schools in Waikato, New Zealand. In 2007, sixty-two control schools were engaged in the programme, and by 2011, all but two of the 235 schools in the region were engaged. Energizers (trained nutrition and physical activity specialists) work with eight to twelve schools each to achieve the goals of the programme, which are based on healthier eating and enhanced physical activity. In 2011, indices of obesity and physical fitness of 2474 younger (7·58 (sd 0·57) years) and 2330 older (10·30 (sd 0·51) years) children attending 193 of the 235 primary schools were compared with historical measurements. After adjusting for age, sex, ethnicity, socio-economic status (SES) and school cluster effects, the combined prevalence of obesity and overweight among younger and older children in 2011 was lower by 31 and 15 %, respectively, than that among 'unEnergized' children in the 2004 to 2006 RCT. Similarly, BMI was lower by 3·0 % (95 % CI - 5·8, - 1·3) and 2·4 % (95 % CI - 4·3, - 0·5). Physical fitness (time taken to complete a 550 m run) was significantly higher in the Energized children (13·7 and 11·3 %, respectively) than in a group of similarly aged children from another region. These effects were observed for boys and girls, both indigenous M?ori and non-M?ori children, and across SES. The long-term regional commitment to the Energize programme in schools may potentially lead to a secular reduction in the prevalence of overweight and obesity and gains in physical fitness, which may reduce the risk of developing obesity and type 2 diabetes.",
Arsenic,2088478,"Sub-microscopic gametocyte carriage in febrile children living in different areas of Gabon Abstract: <strong>BACKGROUND: </strong>Considering malaria prevalence declines in parts of sub-Saharan Africa, such as Gabon, identification of the human infectious reservoir is important for successful malaria control. Microscopic and sub-microscopic parasites contribute to malaria transmission. The aim of the present study was to evaluate the proportion of microscopic and sub-microscopic gametocyte carriers among febrile patients in two different areas of Gabon.<br /><br /><strong>METHODS: </strong>Samples from febrile children aged less than 11 years old were collected from February 2008 to January 2009 at two health centres of Gabon. Patients were screened for the presence of asexual Plasmodium falciparum parasites. Gametocyte carriage was determined by microscopy and QT-NASBA.<br /><br /><strong>RESULTS: </strong>Gametocytes were detected in 5.3% (n = 16/304) of children by microscopy compared to 45.7% (n = 139/304) by QT-Nasba. Sub-microscopic gametocyte carriage (ie microscopy negative and QT-Nasba positive) was found in 89.2% (n = 124/139) of patients. Among patients with microscopically detected trophozoites, the proportion of sub-microscopic gametocyte (SMG) carriers was 58.4% (n = 118/202) and 6% in samples from children with negative slides (p &lt; 0.01). In Oyem, where malaria prevalence is three-fold higher than in Owendo, SMG carriage was more frequent (49.0% vs 32.6% in Owendo; p &lt; 0.01).<br /><br /><strong>CONCLUSION: </strong>Sub-microscopic gametocytaemia is common among Gabonese febrile children. They might strongly contribute to maintain malaria transmission. However, further analysis of sub-microscopic parasite carriage among asymptomatic individuals will be helpful to better characterize malaria transmission.",
Arsenic,1251010,"KlRox1p contributes to yeast resistance to metals and is necessary for KlYCF1 expression in the presence of cadmium Abstract: We have characterized the KlROX1 gene from Kluyveromyces lactis and verified that it does not regulate the hypoxic response in this yeast, oppositely to the Saccharomyces cerevisiae homologue ScROX1. The KlROX1 promoter is not regulated by KlHap1p or KlRox1p in response to changes aerobiosis/hypoxia. Besides, KlRox1p expression only partially represses ScANB1 in S. cerevisiae and does not regulate the ScANB1 and KlHEM13 promoters in K. lactis. KlRox1p does not interact either with KlTup1p or KlSsn6p or with their homologues ScTup1p and ScSsn6p, which are components of the general co-repressor factor that mediates the transcriptional repression exerted by ScRox1p in S. cerevisiae. We have found that KlROX1 mediates the response to arsenate and cadmium and, in the presence of cadmium, it is necessary for KlYCF1 expression, a gene encoding a protein with homology to the yeast cadmium and arsenite vacuolar transporter. EMSA assays show that KlRox1p binds, through its HMG domain, to a DNA sequence present in the KlYCF1 promoter. Although in S. cerevisiae the function of ScRox1p in cadmium resistance was already known and linked to regulation of ScFET4 expression, we have found that ScRox1p also regulates ScYCF1transcription and binds to its promoter.",
Arsenic,1027371,"CHEMOPATHOLOGICAL STUDIES WITH COMPOUNDS OF ARSENIC : IV. THE CHARACTER AND DISTRIBUTION OF RENAL INJURY PRODUCED BY ARSENICALS AS INDICATED BY THE PROCESSES OF REPAIR Abstract: 1. The processes of repair in the kidneys of guinea pigs after sublethal doses of certain arsenical compounds indicate that all arsenicals do not produce a purely vascular type of renal injury. 2. While some arsenicals produce a predominantly vascular injury and others produce a predominantly tubular injury, both these tissue elements are undoubtedly always affected, although in varying proportion. In addition, the interstitial connective tissue is probably always affected. The diffuse proliferation of this tissue may be relatively conspicuous in the processes of repair after arsenicals that cause but slight vascular injury. 3. All red kidneys do not necessarily show identical pictures during the processes of repair; the same is true of pale kidneys. 4. The mode of action of an arsenical compound as a renal toxic agent is bound up with the chemical constitution of the compound.",
Arsenic,1019861,"Power and sample size calculations for generalized regression models with covariate measurement error Abstract: Covariate measurement error is often a feature of scientific data used for regression modelling. The consequences of such errors include a loss of power of tests of significance for the regression parameters corresponding to the true covariates. Power and sample size calculations that ignore covariate measurement error tend to overestimate power and underestimate the actual sample size required to achieve a desired power. In this paper we derive a novel measurement error corrected power function for generalized linear models using a generalized score test based on quasi-likelihood methods. Our power function is flexible in that it is adaptable to designs with a discrete or continuous scalar covariate (exposure) that can be measured with or without error, allows for additional confounding variables and applies to a broad class of generalized regression and measurement error models. A program is described that provides sample size or power for a continuous exposure with a normal measurement error model and a single normal confounder variable in logistic regression. We demonstrate the improved properties of our power calculations with simulations and numerical studies. An example is given from an ongoing study of cancer and exposure to arsenic as measured by toenail concentrations and tap water samples.",
Arsenic,2064230,"Behavior and mechanism of arsenate adsorption on activated natural siderite: evidences from FTIR and XANES analysis Abstract: Activated natural siderite (ANS) was used to investigate its characteristics and mechanisms of As(V) adsorption from aqueous solution. Batch tests were carried out to determine effects of contact time, initial As(V) concentration, temperature, pH, background electrolyte, and coexisting anions on As(V) adsorption. Arsenic(V) adsorption on ANS well-fitted pseudo-second-order kinetics. ANS showed a high-adsorption capacity of 2.19 mg/g estimated from Langmuir isotherm at 25 °C. Thermodynamic studies indicated that As(V) adsorption on ANS was spontaneous, favorable, and endothermic. ANS adsorbed As(V) efficiently in a relatively wide pH range between 2.0 and 10.0, although the removal efficiency was slightly higher in acidic conditions than that in basic conditions. Effects of background electrolyte and coexisting anions were not significant within the concentration ranges observed in high As groundwater. Results of XRD and Fe K-edge XANES analysis suggested ANS acted as an Fe(II)/(III) hybrid system, which was quite effective in adsorbing As from aqueous solution. There was no As redox transformation during adsorption, although Fe(II) oxidation occurred in the system. Two infrared bands at 787 and 872 cm(-1) after As(V) adsorption suggested that As(V) should be predominantly adsorbed on ANS via inner-sphere bidendate binuclear surface complexes.",
Arsenic,1339194,"Response to arsenate treatment in Schizosaccharomyces pombe and the role of its arsenate reductase activity Abstract: Arsenic toxicity has been studied for a long time due to its effects in humans. Although epidemiological studies have demonstrated multiple effects in human physiology, there are many open questions about the cellular targets and the mechanisms of response to arsenic. Using the fission yeast Schizosaccharomyces pombe as model system, we have been able to demonstrate a strong activation of the MAPK Spc1/Sty1 in response to arsenate. This activation is dependent on Wis1 activation and Pyp2 phosphatase inactivation. Using arsenic speciation analysis we have also demonstrated the previously unknown capacity of S. pombe cells to reduce As (V) to As (III). Genetic analysis of several fission yeast mutants point towards the cell cycle phosphatase Cdc25 as a possible candidate to carry out this arsenate reductase activity. We propose that arsenate reduction and intracellular accumulation of arsenite are the key mechanisms of arsenate tolerance in fission yeast.",
Arsenic,1021203,"p53 expression in circulating lymphocytes of non-melanoma skin cancer patients from an arsenic contaminated region in Mexico. A pilot study Abstract: Arsenic is a common environmental toxicant and epidemiological studies associate arsenic exposure with various pathologic disorders and several types of cancer. Skin cancers are the most common arsenic-induced neoplasias and the prevalence of skin lesions has been reported to be significantly elevated in individuals exposed to arsenic via drinking water in Mexico. Being lymphocytes the main cells used for human monitoring, we evaluated the expression of p53 protein in the lymphocytes from 44 healthy individuals and 19 samples from individuals living in a chronic arsenicism endemic region. Of the latter group, 12 individuals had non-melanoma skin cancer and 9 of them expressed p53 in the circulating lymphocytes, whereas only one of the 7 non-cancer arsenic exposed individuals expressed it. In the healthy non-arsenic exposed group only one from 44 individuals expressed the protein. These results suggest a clear relationship between non-melanoma skin cancer and p53 expression in circulating lymphocytes. p53 expression in circulating lymphocytes should be evaluated as a potential biomarker of effect or susceptibility.",
Arsenic,1256732,"POLYCOMB (PcG) PROTEINS, BMI1 AND SUZ12, REGULATE ARSENIC-INDUCED CELL TRANSFORMATION Abstract: Inorganic arsenic is a well-documented human carcinogen associated with cancers of the skin, lung, liver, and bladder. However, the underlying mechanisms explaining the tumorigenic role of arsenic are not well understood. The present study explored a potential mechanism of cell transformation induced by arsenic exposure. Exposure to a low dose (0.5 ?M) of arsenic trioxide (As2O3) caused transformation of BALB/c 3T3 cells. In addition, in a xenograft mouse model, tumor growth of the arsenic-induced transformed cells was dramatically increased. In arsenic-induced transformed cells, polycomb group (PcG) proteins, including BMI1 and SUZ12, were activated resulting in enhanced histone H3K27 tri-methylation levels. On the other hand, tumor suppressor p16INKa and p19ARF mRNA and protein expression were dramatically suppressed. Introduction of small hairpin (sh) RNA-BMI1 or -SUZ12 into BALB/c 3T3 cells resulted in suppression of arsenic-induced transformation. Histone H3K27 tri-methylation returned to normal in BMI1- or SUZ12- knockdown BALB/c 3T3 cells compared with BMI1- or SUZ12-wildtype cells after arsenic exposure. As a consequence, the expression of p16INKa and p19ARF was recovered in arsenictreated BMI1- or SUZ12-knockdown cells. Thus, arsenic-induced cell transformation was blocked by inhibition of PcG function. Taken together, these results strongly suggest that the polycomb proteins, BMI1 and SUZ12 are required for cell transformation induced by organic arsenic exposure.",
Arsenic,2088426,Investigating the Concentrations of Different Elements in Soil and Plant Composition from a Mining Area Abstract: ,
Arsenic,1794805,"Evaluation of the carcinogenicity of gallium arsenide Abstract: Gallium arsenide (GaAs) is an important semiconductor material. In 2-year inhalation studies, GaAs increased the incidence of lung tumors in female rats, but not in male rats or male and female mice. Alveolar proteinosis followed by chronic active inflammation was the predominant non-neoplastic pulmonary findings. IARC classified GaAs as carcinogenic to humans (group 1) based on the assumption that As and Ga ions are bioavailable. The European Chemical Agency Risk Assessment Committee concluded that GaAs should be classified into Carcinogenicity Category 1B (presumed to have carcinogenic potential for humans; ECHA). We evaluate whether these classifications are justified. Physico-chemical properties of GaAs particles and the degree of mechanical treatment are critical in this evaluation. The available data on mode of action (MOA), genotoxicity and bioavailability do not support the contribution of As or Ga ions to the lung tumors in female rats. Most toxicological studies utilized small particles produced by strong mechanical treatment, destroying the crystalline structure. The resulting amorphous GaAs is not relevant to crystalline GaAs at production and processing sites. The likely tumorigenic MOA is lung toxicity related to particulate-induced inflammation and increased proliferation. It is concluded that there is no evidence for a primary carcinogenic effect of GaAs.",
Arsenic,1349494,"Effects of arsenic on nutrients uptake of wheat (Triticum aestivum L) at different growth stages Abstract: Arsenic (As) levels in soils have been elevated, especially in some wheat-producing areas of China. Understanding the effects of arsenic pollution on wheat (Triticum aestivum L) nutrient elements is of major significance for food production and security. A soil pot experiment was carried out to study the uptake of nutrient elements and arsenic at different growth stages. Arsenic concentrations in wheat shoots is ear sprouting stage > jointing stage > tillering stage. Ear sprouting stage was the main stage that arsenic could affect the nutrient elements uptake. When arsenic concentration in soil was â‰¤ 60 mg/kg, arsenic increased the straw P, N and K concentrations at the jointing and ear sprouting stages and enhanced the biomass as well as other agronomic parameters such as grain yield. The increase in wheat biomass and yield probably resulted from P, N, K abundance. However, when soil arsenic was â‰¥ 80 mg/kg, arsenic significantly decreased macroelement (P, K and N) concentrations in the shoots. The reduction in wheat biomass and yield at high arsenic levels probably resulted from both arsenic phytotoxicity and nutrient elements lack. The relationship between shoots arsenic and shoots N, P, K concentrations was quadratic equations. The Cu, Fe, Zn concentrations in wheat shoots significantly were decreased and they were negatively linearly correlated with arsenic concentrations in wheat shoots (RÂ² = 0.7064, 0.8265 and 0.8302, respectively). The highest arsenic concentration in wheat grains was 0.39 mg/kg and did not exceed the maximum permissible limit for food stuffs of 0.7 mg/kg.",
Arsenic,656883,"In vitro long-term cytotoxicity testing of 27 MEIC chemicals on Hep G2 cells and comparison with acute human toxicity data Abstract: Within the framework of the EDIT (Evaluation guided Development of In vitro Toxicity and toxicokinetic tests) programme, the long-term cytotoxicity of 27 chemicals was investigated on Hep G2 cells. The first step in the experiments was to determine the PI50(24h) of the chemicals. This is the concentration of compound needed to reduce the total protein content by 50% after 24 h of treatment. In the long-term experiments the chemicals were tested in six different concentrations, using the PI50(24h) as maximum concentration. The cells were treated twice a week with the same concentration of test compound and were trypsinised and counted once a week (dynamic culture). The number of cells was compared to the number of cells of the control. Three major long-term cytotoxicity patterns could be distinguished. After 6 weeks, the EC50(6w)s were determined. This is the concentration of compound needed to reduce the number of cells by 50% after 6 weeks of treatment. These values were compared with the PI50(24h). A good correlation was found for the 27 chemicals (r(2)=0.860). After 6 weeks, the concentration of test compound needed to reduce the total cell protein content by 50% after 24 h after 6 weeks of pretreatment of the cells with a particular concentration of test compound was measured: the PI50(24h-6w). For the majority of compounds there is no difference between the PI50(24h) and the PI50(24h-6w). For ethanol, arsenic (III) oxide, verapamil hydrochloride and orphenadrine, the PI50(24h-6w) increased in comparison to the PI50(24h). For some compounds a doseresponse was observed, indicating that the cells have become more resistant or more sensitive. Linear regression analysis revealed a good correlation (r(2)=0.709) between the EC50(6w) and the human acute toxicity. All these data indicate that a good alternative test may be found for predicting the long-term human toxicity.",
Arsenic,1034309,"Increase in the synthesis of a Mr 32,000 protein in BALB/c 3T3 cells after treatment with tumor promoters, chemical carcinogens, metal salts, and heat shock Abstract: The synthesis of a Mr 32,000 protein (p32) is enhanced as early as 2 h after the addition of tumor-promoting phorbol esters to BALB/c 3T3 cells. Among various compounds tested thus far, methyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, L-ascorbic acid, sodium deoxycholate, p-tosyl-L-phenylalanine chloromethyl ketone, p-tosyl-L-lysine chloromethyl ketone, 3,3'-diaminobenzidine, and some of the metal salts stimulated the synthesis of p32 to varying extents. p32 might be one of the heat shock proteins because its synthesis was also stimulated by heat shock or sodium arsenite. The synergisms of the effects of different compounds on p32 synthesis suggest that the expression of a p32 gene is regulated through at least three pathways. Possible roles of protein kinases in p32 gene expression are discussed.",
Arsenic,1292196,"Consumption of arsenic and other elements from vegetables and drinking water from an arsenic-contaminated area of Bangladesh Abstract: The study assesses the daily consumption by adults of arsenic (As) and other elements in drinking water and home-grown vegetables in a severely As-contaminated area of Bangladesh. Most of the examined elements in drinking water were below the World Health Organization (WHO) guideline values except As. The median concentrations of As, cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), lead (Pb), Mn, nickel (Ni), and zinc (Zn) in vegetables were 90?gkg(-1), 111?gkg(-1), 0.80mgkg(-1), 168?gkg(-1), 13mgkg(-1), 2.1mgkg(-1), 65mgkg(-1), 1.7mgkg(-1), and 50mgkg(-1), respectively. Daily intakes of As, Cd, Cr, Co, Cu, Pb, manganese (Mn), Ni, and Zn from vegetables and drinking water for adults were 839?g, 2.9?g, 20.8?g, 5.5?g, 0.35mg, 56.4?g, 2.0mg, 49.1?g, and 1.3mg, respectively. The health risks from consuming vegetables were estimated by comparing these figures with the WHO/FAO provisional tolerable weekly or daily intake (PTWI or PTDI). Vegetables alone contribute 0.05?g of As and 0.008mg of Cu per kg of body weight (bw) daily; 0.42?g of Cd, 8.77mg of Pb, and 0.03mg of Zn per kg bw weekly. Other food sources and particularly dietary staple rice need to be evaluated to determine the exact health risks from such foods.",
Arsenic,628415,"Helper T cell subpopulations from women are more susceptible to the toxic effect of sodium arsenite in vitro Abstract: Arsenic is known to produce inhibition as well as induction of proliferative responses in animal and human cells depending on the doses. Despite the amount of information on the immunotoxic effects of arsenic exposure in different animal models, little is known in humans. Arsenic susceptibility of lymphocyte subpopulations (T helper (Th), CD4+; T cytotoxic (Tc), CD8+) and whether arsenic effects are gender related are still to be determined. This work evaluated the in vitro toxicity of sodium arsenite on human T lymphocyte subpopulations from men and women. Peripheral blood mononuclear cells (PBMC) obtained from healthy young men and women were treated with sodium arsenite (0.01, 0.1, and 1 microM). We assessed cell viability, cell proliferation, and the proportion of Th and Tc cells after 48 or 72h of arsenic exposure in resting and phytohemagglutinin M (PHA)-activated PBMC. We observed that sodium arsenite at 1 microM was more toxic for Th than for Tc cells in PBMC from women. Besides, T lymphocytes from women were more affected by the cell proliferation inhibition induced by arsenic, suggesting that women could be more susceptible to the toxic and immunotoxic effects caused by arsenic exposure.",
Arsenic,1352890,REMOVAL OF ARSENATE (V) BY SURFACTANT-MODIFIED ACTIVATED CARBON Abstract: ,
Arsenic,1021537,"Assessment of the State of the Gibel Carp Carassius auratus gibelio in the Amur River Basin: Heavy-Metal and Arsenic Concentrations and Histopathology of Internal Organs Abstract: This study describes the concentrations of heavy metals and arsenic (As) and the basic histopathological changes in the internal organs of gibel carp Carassius auratus gibelio from five sites of the Amur River basin. Gibel carp from Sindinskaya Passage had the highest liver concentrations of zinc (Zn) (31.95 ± 13.443), copper (Cu) (12.52 ± 5.746), manganese (9.22 ± 8.121), and cadmium (0.37 ± 0.660 mg/kg wet weight [ww]) compared with fish captured from the Bol'shoi Ussuriiskii Island area and Kadi Lake; however, concentrations of nickel (0.22 ± 0.156 mg/kg ww) were not significantly different, and concentrations of lead (0.19 ± 0.121 mg/kg ww) were higher than those in fish from Kadi Lake. Mean concentrations of metals and As in muscles were lower than Russia's recommended limits for food products; however, concentrations of Cu, Zn, and Hg in individual fish were greater than the limit. Kidney disease was detected in 100% of sampled carp. Kidney disease was characterized by the formation of numerous granulomas in kidney tissues between the renal tubules. The degree of granulomatosis varied among sites. Granulomatous kidney disease in gibel carp is widespread in many reservoirs of the lower Amur River basin. The following histopathological changes were detected in liver: vacuolization of hepatocytes, hypertrophy of multiple hepatocytes, binuclearity, presence of numerous irregularly shaped nuclei in hepatocytes, karyopyknosis, diffuse necrosis of hepatocytes (in some cases focal), and edema. Necrotic changes in hepatocytes, which are important indices of the toxic effect of pollutants, were found in the majority of investigated carp from the lower Amur River basin. Some fish had simultaneous pathological alterations in multiple organs.",
Arsenic,1936063,"Inorganic Arsenic in the Japanese Diet: Daily Intake and Source Abstract: The concentrations of arsenic (As) species in 19 food composites prepared from 159 food items purchased in Shizuoka city, Japan, were determined (1) to estimate total daily intake of inorganic As (InAs) and some organic As species and (2) to determine food contributing to total daily InAs intake. As analysis included extraction of As species with a synthetic gastric juice (0.07 mol/L HCl + 0.01 % pepsin) from food composite and high-performance liquid chromatography-high efficiency photo-oxidation-hydride generation-inductively coupled plasma mass spectrometry. InAs was detected in 9 of 19 food composites at a concentration of 0.423-450 ng As/g fresh-weight. Daily intake of InAs from cereals was greatest (13 ?g/person/day) followed by algae (5.7 ?g/person/day), and the intake from the two categories constituted 90 % of the total daily InAs intake of adults (21 ?g/person/day on a bioaccessible-fraction basis and 24 ?g/person/day on a content basis). Analysis of individual food items showed that rice and hijiki contributed virtually 100 % of InAs from cereals and algae, respectively. The present survey indicated that InAs from rice and hijiki consumption contributed to total daily InAs intake and consequently to significant cancer risk of the general Japanese population. Daily intake of some organic forms of As and their contributing food categories was also estimated.",
Arsenic,1339107,"Delayed temporal increase of hepatic Hsp70 in ApoE knockout mice after prenatal arsenic exposure Abstract: Prenatal arsenic exposure accelerates atherosclerosis in ApoE(-/-) mice by unknown mechanism. Arsenic is an hepatotoxicant, and liver disease increases atherosclerosis risk. Prenatal arsenic exposure may predispose to liver disease by priming for susceptibility to other environmental insults. Earlier microarray analyses showed prenatal arsenic exposure increased Hsc70 (HspA8) and Hsp70 (HspA1a) mRNAs in livers of 10 week old mice. We determined effects of prenatal arsenic exposure on hepatic Hsp70 and Hsc70 expression by western blot and on DNA methylation by methyl acceptance assay during prenatal and postnatal development. Pregnant ApoE(-/-) mice were given drinking water containing 85 mg/L NaAsO(2) (49 ppm arsenic) from gestation day (GD) 8 - 18. Hsp70 and Hsc70 expression and DNA methylation were determined in GD18 fetuses, and 3, 10 and 24 week old mice. Hsc70 expression was unchanged at all ages. Hsp70 induction was observed at 3 and 10 weeks, but was unchanged in GD18 and 24 week livers. Global DNA methylation increased with age; arsenic had no effects. Bisulfite sequencing of DNA from livers of 10 week old mice showed Hsp70 promoter region methylation was unchanged, but methylation was increased within the transcribed region. Hsf1 and Nrf2 nuclear translocation were investigated as potential mechanisms of Hsp70 induction, and found unaltered. Putative binding sites were identified in HSP70 for in utero arsenic exposure suppressed microRNAs suggesting a possible mechanism. Thus, prenatal arsenic exposure causes delayed temporal hepatic Hsp70 induction, suggesting a transient state of stress in livers which can predispose the mice to developing liver disease.",
Arsenic,1337310,"Assessment of prenatal exposure to arsenic in Tenerife Island Abstract: <strong>INTRODUCTION: </strong>Increasing awareness of the potential chronic health effects of arsenic (As) at low exposure levels has motivated efforts to better understand impaired child development during pregnancy by biomarkers of exposure. The aims of this study were to evaluate the prenatal exposure to As by analysis of an alternative matrix (meconium), to examine its effects on neonatal outcomes and investigate the association with maternal lifestyle and dietary habits during pregnancy.<br /><br /><strong>METHODS: </strong>A transversal descriptive study was conducted in Tenerife (Spain). A total of 96 mother-child pairs participated in the study. A questionnaire on sociodemographic, lifestyle and dietary habits during pregnancy was administered the day after the delivery. Analysis of total As in meconium was performed by inductively coupled plasma-optical emission spectrometer.<br /><br /><strong>RESULTS: </strong>Total As was detected in 37 (38.5%) meconium samples. The univariate logistic regression model indicates that prenatal exposure to As was associated with a low intake of eggs per week (OR 0.56; CI (95%): 0.34-0.94) during pregnancy. Conversely, frequent intake of vegetables was associated with prenatal As exposure (OR: 1.19; CI (95%): 1.01-1.41) and frequent intake of processed meat (as bacon, Frankfurt's sausage, and hamburger) shows a trend to As prenatal exposure (OR: 8.54; CI (95%): 0.80-90.89). The adjusted multivariate logistic regression model indicates that only frequent intake of vegetables maintains the association (OR: 1.31; CI (95%): 1.02-1.68).<br /><br /><strong>CONCLUSION: </strong>The studied population presented a low As exposure and was not associated with neonatal effects. Maternal consumption of vegetables during pregnancy was associated with detectable meconium As levels; however the concentration detected in meconium was too low to be considered a major public health concern in this geographical area.",
Arsenic,1326814,"Sodium arsenite inhibits migration of extravillous trophoblast cells in vitro Abstract: This study used a first-trimester human extravillous trophoblast (EVT) cell line, HTR-8/SVneo, to investigate whether sodium arsenite (AsNaO(2)) reduces human EVT migration and invasion. Treatments with 2.5 microM AsNaO(2) or less (&lt; or =187.3 microg/L), concentrations that are relevant to human exposures in drinking water, were sublethal to HTR-8/SVneo cells. A 72-h exposure to sodium arsenite inhibited cell migration in a concentration-dependent manner at 0.625, 1.25 and 2.5 microM. Significant changes in cell proliferation were not observed under these treatment conditions. Moreover, inhibition of cell migration was unrelated to phosphorylation of focal adhesion kinase Tyr397. In contrast to cell migration, 72-h exposures to AsNaO(2) (0.3125-2.5 microM) had no significant effects on cell invasion, nor on the activities and protein expression of matrix metalloproteinase (MMP) 2 and MMP9. Because trophoblast migration is important for placentation, these results suggest an effect that could contribute to insufficiency of placental development and adverse pregnancy outcomes.",
Arsenic,732047,"Arsenite and insulin exhibit opposing effects on epidermal growth factor receptor and keratinocyte proliferative potential Abstract: Previous work has suggested that arsenic exposure contributes to skin carcinogenesis by preserving the proliferative potential of human epidermal keratinocytes, thereby slowing the exit of putative target stem cells into the differentiation pathway. To find a molecular basis for this action, present work has explored the influence of arsenite on keratinocyte responses to epidermal growth factor (EGF). The ability of cultured keratinocytes to found colonies upon passaging several days after confluence was preserved by arsenite and EGF in an additive fashion, but neither was effective when the receptor tyrosine kinase activity was inhibited. Arsenite prevented the loss of EGF receptor protein and phosphorylation of tyrosine 1173, preserving its capability to signal. The level of nuclear beta-catenin was higher in cells treated with arsenite and EGF in parallel to elevated colony forming ability, and expression of a dominant negative beta-catenin suppressed the increase in both colony forming ability and yield of putative stem cells induced by arsenite and EGF. As judged by expression of three genes regulated by beta-catenin, this transcription factor had substantially higher activity in the arsenite/EGF-treated cells. Trivalent antimony exhibited the same effects as arsenite. A novel finding is that insulin in the medium induced the loss of EGF receptor protein, which was largely prevented by arsenite exposure.",
Arsenic,628716,"Arsenite enhances tumor necrosis factor-alpha-induced expression of vascular cell adhesion molecule-1 Abstract: Epidemiological studies demonstrated a high association of vascular diseases with arsenite exposure. We hypothesize that arsenite potentiates the effect of proinflammatory cytokines on vascular endothelial cells, and hence contributes to atherosclerosis. In this study, we investigated the effect of arsenite and its induction of glutathione (GSH) on vascular cell adhesion molecule-1 (VCAM-1) protein expression in human umbilical vein endothelial cells (HUVECs) in response to tumor necrosis factor-? (TNF-?), a typical proinflammatory cytokine. Our study demonstrated that arsenite pretreatment potentiated the TNF-?-induced VCAM-1 expression with up-regulations of both activator protein-1 (AP-1) and nuclear factor-?B (NF-?B). To elucidate the role of GSH in regulation of AP-1, NF-?B, and VCAM-1 expression, we employed l-buthionine (S,R)-sulfoximine (BSO), a specific ?-glutamylcysteine synthetase (?-GCS) inhibitor, to block intracellular GSH synthesis. Our investigation revealed that, by depleting GSH, arsenite attenuated the TNF-?-induced VCAM-1 expression as well as a potentiation of AP-1 and an attenuation of NF-?B activations by TNF-?. Moreover, we found that depletion of GSH would also attenuate the TNF-?-induced VCAM-1 expression with a down-regulation of the TNF-?-induced NF-?B activation and without significant effect on AP-1. On the other hand, the TNF-?-induced VCAM-1 expression could be completely abolished by inhibition of AP-1 or NF-?B activity, suggesting that activation of both AP-1 and NF-?B was necessary for VCAM-1 expression. In summary, we demonstrate that arsenite enhances the TNF-?-induced VCAM-1 expression in HUVECs via regulation of AP-1 and NF-?B activities in a GSH-sensitive manner. Our present study suggested a potential mechanism for arsenite in the induction of vascular inflammation and vascular diseases via modulating the actions of proinflammatory cytokines.",
Arsenic,85950,"Biological monitoring of environmental pollution and human exposure to metals in Tarragona, Spain - Part I: Levels in hair of school children Abstract: Hair samples of 124 school children (11-13 years old) living in 3 residential areas in the neighborhood of a hazardous waste incinerator (HWI) now under construction (Tarragona, Spain) were analyzed for arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) concentrations by ICP-MS. Beryllium, Tl, and V levels were under the respective detection limits. The concentrations (mug/g) of the remaining 8 elements showed the following ranges: 0.01-0.10 for As, 0.03-0.73 for Cd, 0.13-3.23 for Cr, 0.09-2.54 for Hg, 0.04-0.99 for Mn, 0.10-3.18 for Ni, 0.38-23.83 for Pb, and 0.01-2.80 for Sn. No differences in relation to sex were observed. By contrast, significant differences with respect to the place of residence were found in the hair concentrations of As, Cd, Cr, Hg, and Sn. In general terms, the current metal levels in hair of school children are of the same order of magnitude or even lower than reference values for these elements. These results will be useful for future assessments of the impact of metal emissions from the new HWI on public health.",
Arsenic,1349768,"Arsenic metabolism in a freshwater food chain Abstract: Accumulation and the biotransformation of arsenic were investigated in a three-step freshwater food chain consisting of an autotroph (Chlorella sp.), a grazer (Moina sp.) and a carnivore (Carassius sp.). The grazer and carnivore survived in arsenic-containing water below 3 and 25 mg As (V) L-1, respectively. These organisms also accumulated arsenic (V) from water and methylated part of it. The arsenic-accumulation from food decreased one order of magnitude and the biomethylation of the arsenic increased, successively with an elevation in the trophic level.",
Arsenic,1936070,"Stable transformation of ferns using spores as targets: Pteris vittata (Chinese brake fern) and Ceratopteris thalictroides (C-fern 'Express') Abstract: Ferns (Pteridophyta) are very important members of the plant kingdom that lag behind other taxa with regards to our understanding of their genetics, genomics, and molecular biology. We report here the first instance of stable transformation of fern with recovery of transgenic sporophytes. Spores of the arsenic hyperaccumulating fern Pteris vittata (Chinese brake fern) and tetraploid Ceratopteris thalictroides (C-fern 'Express') were stably transformed by Agrobacterium tumefaciens with constructs containing the P. vittata actin promoter driving a GUSPlus reporter gene. Reporter gene expression assays were performed on multiple tissues and growth stages of gametophytes and sporophytes. Southern blot analysis confirmed stable transgene integration in recovered sporophytes and also confirmed that no plasmid from Agrobacterium was present in the sporophyte tissues. We recovered seven independent transformants of P. vittata and four independent C. thalictroides transgenics. Inheritance analyses using GUS histochemical staining revealed that the GUS transgene was stably expressed in second (T2) generation C. thalictroides sporophytic tissues. In an independent experiment, the gusA gene that was driven by the 2x CaMV 35S promoter was bombarded into P. vittata spores using biolistics in which putatively stable transgenic gametophytes were recovered. Transformation procedures required no tissue culture or selectable marker genes. However, we did attempt to use hygromycin selection, which was ineffective to recover transgenic ferns. This simple stable transformation method should help facilitate functional genomics studies in ferns.",
Arsenic,627320,"Arsenic disrupts cellular levels of p53 and mdm2: A potential mechanism of carcinogenesis Abstract: The antitumor protein p53 plays a critical role in DNA repair. Inorganic arsenic exposure is associated with a wide variety of human tumors, particularly of the skin. To investigate how inorganic arsenic might interfere with DNA repair and lead to greater incidence of hyperkeratosis and skin tumors, we exposed human keratinocytes (HaCaT) to environmentally relevant concentrations of arsenite for 14 days. Arsenite reduced p53 levels while concomitantly increasing the p53 regulatory protein mdm2 levels in a dose- and time-dependent manner. We propose the disruption of the p53-mdm2 loop regulating cell cycle arrest as a model for arsenic-related skin carcinogenesis and it may be important in tumors with elevated mdm2 levels.",
Arsenic,1329308,"Suppressive effect of 1,4-phenylene diisothiocyanate on N-butyl-N-(4-hydroxybutyl)nitrosamine-induced urinary bladder carcinogenesis in male ICR mice Abstract: The modifying effects of dietary administration of 1,4-phenylene diisothiocyanate (DITC) on N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced urinary bladder carcinogenesis during the initiation and post-initiation phases were examined in male ICR mice. Five-week-old animals were divided into 5 groups. Groups 1-3 were given BBN (500 ppm) in drinking water for 6 weeks starting at age 6 week. Mice in Group 2 were given the diet containing 100 ppm DITC for 8 weeks during the initiation phase, starting 1 week before BBN exposure. Animals in Group 3 were fed the experimental diet for 24 weeks during the post-initiation phase starting 1 week after the cessation of BBN exposure. Mice in Group 4 were given only the diet containing the test compound, and those in Group 5 were given the basal diet alone throughout the experiment (32 weeks). The frequency of bladder lesions, neoplasms, dysplasia and hyperplasia, was analyzed histopathologically. The cell-proliferation activity estimated by the 5-bromodeoxyuridine labeling index (BrdU-LI), and cell cycle progression by counting cyclin D1-positive cell ratios were compared among the groups using immunohistochemistry. Administration of DITC in the initiation phase reduced significantly the incidence of urinary bladder carcinoma and dysplasia. The frequencies of any lesions of urinary bladder were not reduced by DITC in post-initiation phase. Dietary exposure of this agent in initiation phase reduced significantly both BrdU-LI and cyclin D1-positive cell ratios in any bladder lesions. Administration of DITC in post-initiation phase also significantly reduced BrdU-LI in bladder neoplasms and hyperplasia and cyclin D1-positive cell ratios in urinary bladder carcinoma as well as dysplasia. These results suggest that dietary DITC could be a preventive agent against BBN-induced bladder carcinogenesis in mice when fed during the initiation phase.",
Arsenic,627144,"Effect of trivalent and pentavalent arsenic in causing chromosome alterations in cultured Chinese hamster ovary (CHO) cells Abstract: Sodium salts of trivalent and pentavalent arsenic were tested for their effect in inducing chromosome aberrations and sister-chromatid exchange (SCE) in cultured Chinese hamster ovary (CHO) cells. It was discovered that arsenite (As 3) produced excessive endoreduplication of the chromosomes at higher levels. No endoreduplication was observed with arsenate (As 5) treatment. These agents also elevated the frequencies of SCE, but less so compared to aberrations. The results obtained indicate that arsenic may be carcinogenic in animal system.",
Arsenic,1026372,"Induction of human promyelocytic leukemia HL-60 cell differentiation into monocytes by arsenic sulphide: involvement of serine/threonine protein phosphatases Abstract: The clinical efficacy of arsenic sulfide (As(4)S(4)), also known as realgar, in the treatment of leukemia in China is prompting people to explore the underlying mechanism. We examined the realgar-induced differentiation in human promyelocytic leukemia cell line HL-60. Cells exhibited proliferation inhibition when treated with 0.10-1.5 microM of realgar, and underwent monocytic differentiation as indicated by morphological changes, NBT reduction assay, and cytofluorometric analyses of the cell surface antigens, CD11b and CD14. Accompanying the differentiation, the activity of serine/threonine protein phosphatase type 1 (PP1) and type 2A (PP2A) were enhanced, whereas the activity of PP2B remained virtually the same compared to the control. When cells were treated with realgar in the presence of an inhibitor of PP1 and 2A or an inhibitor of PP2B, the differentiation of the cells was partially suppressed as revealed by NBT reduction assay and the expression of CD14. Our data demonstrate that realgar induces monocytic differentiation in HL-60 cells and that some serine/threonine protein phosphatases may be involved in the process.",
Arsenic,737165,"Carcinogenicity of dimethylarsinic acid in male F344 rats and genetic alterations in induced urinary bladder tumors Abstract: Arsenic is a well-documented human carcinogen, and contamination with this heavy metal is of global concern, presenting a major issue in environmental health. However, the mechanism by which arsenic induces cancer is unknown, in large part due to the lack of an appropriate animal model. In the present set of experiments, we focused on dimethylarsinic acid (DMA), a major metabolite of arsenic in most mammals including humans. We provide, for the first time, the full data, including detailed pathology, of the carcinogenicity of DMA in male F344 rats in a 2-year bioassay, along with the first assessment of the genetic alteration patterns in the induced rat urinary bladder tumors. Additionally, to test the hypothesis that reactive oxygen species (ROS) may play a role in DMA carcinogenesis, 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in urinary bladder was examined. In experiment 1, a total of 144 male F344 rats at 10 weeks of age were randomly divided into four groups that received DMA at concentrations of 0, 12.5, 50 and 200 p.p.m. in the drinking water, respectively, for 104 weeks. From weeks 97-104, urinary bladder tumors were observed in 8 of 31 and 12 of 31 rats in groups treated with 50 and 200 p.p.m. DMA, respectively, and the preneoplastic lesion, papillary or nodular hyperplasias (PN hyperplasia), was noted in 12 and 14 rats, respectively. DMA treatment did not cause tumors in other organs and no urinary bladder tumors or preneoplastic lesions were evident in the 0 and 12.5 p.p.m.-treated groups. Urinary levels of arsenicals increased significantly in a dose-responsive manner except for arsenobetaine (AsBe). DMA and trimethylarsine oxide (TMAO) were the major compounds detected in the urine, with small amounts of monomethylarsonic acid (MMA) and tetramethylarsonium (TeMa) also detected. Significantly increased 5-bromo-2'-deoxyuridine (BrdU) labeling indices were observed in the morphologically normal epithelium of the groups treated with 50 and 200 p.p.m. DMA. Mutation analysis showed that DMA-induced rat urinary bladder tumors had a low rate of H-ras mutations (2 of 20, 10%). No alterations of the p53, K-ras or beta-catenin genes were detected. Only one TCC (6%) demonstrated nuclear accumulation of p53 protein by immunohistochemistry. In 16 of 18 (89%) of the TTCs and 3 of 4 (75%) of the papillomas, decreased p27(kip1) expression could be demonstrated. Cyclin D1 overexpression was observed in 26 of 47 (55%) PN hyperplasias, 3 of 4 (75%) papillomas, and 10 of 18 (56%) TCCs. As a molecular marker of oxidative stress, increased COX-2 expression was noted in 17 of 18 (94%) TCCs, 4 of 4 (100%) papillomas, and 39 of 47 (83%) PN hyperplasias. In experiment 2, 8-OHdG formation in urinary bladder was significantly increased after treatment with 200 p.p.m. DMA in the drinking water for 2 weeks compared with the controls. The studies demonstrated DMA to be a carcinogen for the rat urinary bladder and suggested that DMA exposure may be relevant to the carcinogenic risk of inorganic arsenic in humans. Diverse genetic alterations observed in DMA-induced urinary bladder tumors imply that multiple genes are involved in stages of DMA-induced tumor development. Furthermore, generation of ROS is likely to play an important role in the early stages of DMA carcinogenesis.",
Arsenic,2149110,"A methodology for the sustainability assessment of arsenic mitigation technology for drinking water Abstract: In this paper we show how the process analysis method (PAM) can be applied to assess the sustainability of options to mitigate arsenic in drinking water in rural India. Stakeholder perspectives, gathered from a fieldwork survey of 933 households in West Bengal in 2012 played a significant role in this assessment. This research found that the 'most important' issues as specified by the technology users are cost, trust, distance from their home to the clean water source (an indicator of convenience), and understanding the health effects of arsenic. We show that utilisation of a technology is related to levels of trust and confidence in a community, making use of a composite trust-confidence indicator. Measures to improve trust between community and organisers of mitigation projects, and to raise confidence in technology and also in fair costing, would help to promote successful deployment of appropriate technology. Attitudes to cost revealed in the surveys are related to the low value placed on arsenic-free water, as also found by other investigators, consistent with a lack of public awareness about the arsenic problem. It is suggested that increased awareness might change attitudes to arsenic-rich waste and its disposal protocols. This waste is often currently discarded in an uncontrolled manner in the local environment, giving rise to the possibility of point-source recontamination.",
Arsenic,2337201,"Studies on arsenic transforming groundwater bacteria and their role in arsenic release from subsurface sediment Abstract: Ten different Gram-negative arsenic (As)-resistant and As-transforming bacteria isolated from As-rich groundwater of West Bengal were characterized to assess their role in As mobilization. 16S rRNA gene analysis confirmed the affiliation of these bacteria to genera Achromobacter, Brevundimonas, Rhizobium, Ochrobactrum, and Pseudoxanthomonas. Along with superior As-resistance and As-transformation abilities, the isolates showed broad metabolic capacity in terms of utilizing a variety of electron donors and acceptors (including As) under aerobic and anaerobic conditions, respectively. Arsenic transformation studies performed under various conditions indicated highly efficient As(3+) oxidation or As(5+) reduction kinetics. Genes encoding As(3+) oxidase (aioA), cytosolic As(5+) reductase (arsC), and As(3+) efflux pump (arsB and acr3) were detected within the test isolates. Sequence analyses suggested that As homeostasis genes (particularly arsC, arsB, and acr3) were acquired by most of the bacteria through horizontal gene transfer. A strong correlation between As resistance phenotype and the presence of As(3+) transporter genes was observed. Microcosm study showed that bacterial strain having cytosolic As(5+) reductase property could play important role in mobilizing As (as As(3+)) from subsurface sediment.",
Arsenic,1032692,Preparation of biological tissue for determination of arsenic and selenium by graphite furnace atomic absorption spectrometry Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXINS,
Arsenic,1017471,"Inhalable metal-rich air particles and histone H3K4 dimethylation and H3K9 acetylation in a cross-sectional study of steel workers Abstract: BACKGROUND: Epidemiology investigations have linked exposure to ambient and occupational air particulate matter (PM) with increased risk of lung cancer. PM contains carcinogenic and toxic metals, including arsenic and nickel, which have been shown in in vitro studies to induce histone modifications that activate gene expression by inducing open-chromatin states. Whether inhalation of metal components of PM induces histone modifications in human subjects is undetermined. OBJECTIVES: We investigated whether the metal components of PM determined activating histone modifications in 63 steel workers with well-characterized exposure to metal-rich PM. METHODS: We determined histone 3 lysine 4 dimethylation (H3K4me2) and histone 3 lysine 9 acetylation (H3K9ac) on histones from blood leukocytes. Exposure to inhalable metal components (aluminum, manganese, nickel, zinc, arsenic, lead, iron) and to total PM was estimated for each study subject. RESULTS: Both H3K4me2 and H3K9ac increased in association with years of employment in the plant (p-trend = 0.04 and 0.006, respectively). H3K4me2 increased in association with air levels of nickel [? = 0.16; 95% confidence interval (CI), 0.03-0.3], arsenic (? = 0.16; 95% CI, 0.02-0.3), and iron (? = 0.14; 95% CI, 0.01-0.26). H3K9ac showed nonsignificant positive associations with air levels of nickel (? = 0.24; 95% CI, -0.02 to 0.51), arsenic (? = 0.21; 95% CI, -0.06 to 0.48), and iron (? = 0.22; 95% CI, -0.03 to 0.47). Cumulative exposures to nickel and arsenic, defined as the product of years of employment by metal air levels, were positively correlated with both H3K4me2 (nickel: ? = 0.16; 95% CI, 0.01-0.3; arsenic: ? = 0.16; 95% CI, 0.03-0.29) and H3K9ac (nickel: ? = 0.27; 95% CI, 0.01-0.54; arsenic: ? = 0.28; 95% CI, 0.04-0.51). CONCLUSIONS: Our results indicate histone modifications as a novel epigenetic mechanism induced in human subjects by long-term exposure to inhalable nickel and arsenic.",
Arsenic,1020526,"Arsenic suppresses necrosis induced by selenite in human leukemia HL-60 cells Abstract: Selenium, an essential trace element for humans, has been shown to have anticancer effects. Arsenic, a possibly essential ultratrace element for humans, has been used in the treatment of leukemia. Anticancer effects of selenium and arsenic have been related to their ability to induce apoptosis. Because humans are exposed to diverse trace elements simultaneously, it is important to learn their interrelationship. In this study, we demonstrate that sodium selenite (Na2SeO3) causes apoptosis at 3 microM and necrosis at high concentrations (&gt; 3 microM) in HL-60 cells. Similarly, both sodium arsenite (NaAsO2) at 50 microM and sodium arsenate (Na2HAsO4) induce apoptosis at 500 microM and necrosis at higher concentrations (&gt; 50 microM and &gt; 500 microM, respectively) in HL-60 cells. Arsenite/arsenate, but not selenite, enhances AP-1 DNA-binding activity. This finding indicates different mechanisms through which apoptosis is induced by these two elements. Interestingly, we observed that HL-60 cell necrosis induced by a high concentration (&gt; 3 microM) of selenite was essentially inhibited by arsenic (50 microM of NaAsO2 or 500 microM of Na2HAsO4), which resulted in a net effect of apoptosis. Because AP-1 DNA-binding activity was not induced in the presence of a combination of necrotic amount of selenite and apoptotic amount of arsenite/arsenate, the observed apoptosis apparently was through the mechanism used by selenite. Our results suggest, for the first time, that the toxic necrotic effect of selenite can be neutralized by arsenite/arsenate at the cellular level.",
Arsenic,1343208,MASS-SPECTROMETRY BY RESONANT LASER IONIZATION OF CARBON AND ARSENIC Abstract: ,
Arsenic,2149186,"Intracellular mobility and nuclear trafficking of the stress-activated kinase JNK1 are impeded by hyperosmotic stress Abstract: The c-Jun N-terminal kinases (JNKs) are a group of stress-activated protein kinases that regulate gene expression changes through specific phosphorylation of nuclear transcription factor substrates. To address the mechanisms underlying JNK nuclear entry, we employed a semi-intact cell system to demonstrate for the first time that JNK1 nuclear entry is dependent on the importin ?2/?1 heterodimer and independent of importins ?3, ?4, ?2, ?3, 7 and 13. However, quantitative image analysis of JNK1 localization following exposure of cells to either arsenite or hyperosmotic stress did not indicate its nuclear accumulation. Extending our analyses to define the dynamics of nuclear trafficking of JNK1, we combined live cell imaging analyses with fluorescence recovery after photobleaching (FRAP) protocols. Subnuclear and subcytoplasmic bleaching protocols revealed the slowed movement of JNK1 in both regions in response to hyperosmotic stress. Strikingly, while movement into the nucleus of green fluorescent protein (GFP) or transport of a GFP-T-antigen fusion protein as estimated by initial rates and time to reach half-maximal recovery (t1/2) measures remained unaltered, hyperosmotic stress slowed the nuclear entry of GFP-JNK1. In contrast, arsenite exposure which did not alter the initial rates of nuclear accumulation of GFP, GFP-T-antigen or GFP-JNK1, decreased the t1/2 for nuclear accumulation of both GFP and GFP-JNK1. Thus, our results challenge the paradigm of increased nuclear localization of JNK broadly in response to all forms of stress-activation and are consistent with enhanced interactions of stress-activated JNK1 with scaffold and substrate proteins throughout the nucleus and the cytosol under conditions of hyperosmotic stress.",
Arsenic,1340049,"Opposed arsenite-mediated regulation of p53-survivin is involved in neoplastic transformation, DNA damage, or apoptosis in human keratinocytes Abstract: Biphasic dose-response relationship induced by environmental agents is often characterized with the effect of low-dose stimulation and high dose inhibition. Some studies showed that arsenite may induce cell proliferation and apoptosis via biphasic dose-response relationship in human cells; however, mechanisms underlying this phenomenon are not well understood. Our present study shows that, for human keratinocytes (HaCaT) cells, a low concentration of arsenite activates extracellular signal-regulated kinases (ERKs), which leads to up-regulation of nuclear factor ?B (NF-?B) binding to DNA and to elevated, NF-?B-dependent expression of mot-2 (a p53 inhibitor) and survivin (an inhibitor of apoptosis). Activation of p53 is blocked, and neoplastic transformation is enhanced. Inhibition of ERKs reduces cell proliferation and neoplastic transformation. In contrast, a high concentration of arsenite activates c-Jun N-terminal kinases (JNKs), positive regulators of p53, by binding to p53 and preventing its murine double minute 2 (mdm2)-mediated degradation. The elevated levels of p53 lead to repair of DNA damage and apoptosis. Inhibition of JNKs increases DNA damage but decreases apoptosis. By identifying a mechanism whereby ERKs and JNKs-mediated regulation of the p53-survivin signal pathway is involved in the biphasic effects of arsenite on human keratinocytes, our data expand understanding of arsenite-induced cell proliferation, neoplastic transformation, DNA damage, and apoptosis.",
Arsenic,1338686,"Arsenic-induced toxicity and carcinogenicity: A two-wave cross-sectional study in arsenicosis individuals in West Bengal, India Abstract: In the state of West Bengal in India, over 26 million individuals are exposed to arsenic via drinking water. Dermatological, non-dermatological disorders and cancers are associated with arsenic toxicity. Of late, there has been a decrease in the arsenic concentration in drinking water owing to governmental efforts, raising the possibility of remediation. A cross-sectional study was conducted, where 189 arsenicosis and 171 unexposed individuals were recruited at two time points, (2005-06 and 2010-11) with concomitant decrease in the level of arsenic exposure via drinking water in the arsenicosis group in 2010-11. Parameters studied included dermatological, non-dermatological health status and cytogenetic damage. Decrease of arsenic exposure (190.1??g/l to 37.94??g/l) resulted in significant decline in the number of individuals having dermatological disorders (P&lt;0.01) and in the severity of each dermatological outcome (P&lt;0.0001). Micronucleus formation in urothelial cells and lymphocytes decreased significantly (P&lt;0.001). However, there was a significant (P&lt;0.001) rise in the incidence of each of the non-dermatological diseases, that is, peripheral neuropathy, conjunctivitis and respiratory distress over the period. Thirteen (6.87%) of the initially recruited arsenicosis individuals died of cancer, in this period. Remediation by arsenic-safe drinking water can reduce dermatological manifestations and cytogenetic insult; but is unable to counter the non-dermatological symptoms.Journal of Exposure Science and Environmental Epidemiology advance online publication, 19 September 2012; doi:10.1038/jes.2012.91.",
Arsenic,94734,"A study of inhaled arsenic-74 in man Abstract: Biochemical study of the carcinogenic activity of arsenic (7440382) dusts and fumes by subjecting 11 terminal cancer patients to inhalation tests. Inhalation of smoke from cigarettes adulterated with arsenic-74 shows uptakes of 4.8 percent to 8.8 percent of the total radioactivity. Uptakes of an aerosol solution of arsenic-74 in two patients are found to be 32 percent and 62 percent, respectively. Distribution of the inhaled arsenic-74, as determined with a scinti-scanner, shows a diffuse uptake in seven patients and a tendency to pick up a greater amount in the perihilar areas in four patients. The absorption rate from the bronchial tree is rapid for the first several days and then tapers off slowly. In three patients, an average of 45 percent of the inhaled arsenic is eliminated in the urine in 10 days and 2.5 percent in the stools. The remainder is assumed to be deposited in the body, exhaled, and eliminated in body secretions and excreta over a long period of time.",
Arsenic,1337343,"Low-level arsenic exposure is associated with bladder cancer risk and cigarette smoking: A case-control study among men in Tunisia Abstract: Although exposure to high levels of arsenic is associated with excess bladder cancer risk, lower exposures generally are not. This study represents the first biomonitoring of arsenic exposure in Tunisia and focuses on a possible association with bladder cancer risk. In this context, 124 male bladder cancer cases and 220 controls were recruited and blood samples were analyzed to determine the concentration of As. The study subjects were stratified into median groups based on concentrations of arsenic in their blood. Blood arsenic (B-As) was significantly two to threefold higher in bladder cancer cases than in controls (p?<?0.05). The arsenic concentrations were significantly higher among both smokers and workers in construction. However, neither drinking water nor seafood was found to be incriminated as exposure sources. The adjusted risk ratios for B-As concentration categories 0.1-0.67 and ?0.67 ?g/L were 0.18 (95% CI?=?0.014-2.95) and 2.44 (95% CI?=?1.11-5.35), respectively. Arsenic levels were not found to be associated with tumor grade or stage. The considerable risk in the category of highest cumulative exposure argues for an association between bladder cancer risk and low-level arsenic exposure. Future investigations with larger samples and using techniques that allow the distinction of the different arsenic species should better elucidate this association. Furthermore, the modulation of arsenic level according to the histological grade may be of potential to be used as a diagnostic marker of the disease process and its possible relationship etiologically.",
Arsenic,2337105,"Arsenical copper and bronze in Middle Bronze Age burial sites of southern Portugal: the first bronzes in Southwestern Iberia Abstract: Middle Bronze Age was a transition period in Iberia, characterised by the emergence of bronzes after more than a millennium of a conservative metallurgy of copper with arsenic. Despite its importance there are no relevant studies on MBA metallurgy in Southwestern Iberia due to the absence, until recently, of known settlements and the scarcity of metals. However, recent archaeological excavations have brought to light important finds dated to the SW Iberian Bronze Age such as new burial monuments and open settlements. About 50 artefacts from hypogea, cists and domestic contexts (pits) from Torre Velha 3 (Serpa) and Monte da Cabida 3 (Evora) were analysed by micro-EDXRF, reflected light microscopy, SEM-EDS and Vickers microhardness testing. Radiocarbon dating of their archaeological contexts established a chronology of similar to 1900-1300 cal BC. Despite presenting different burial practices both sites share the almost exclusive use of arsenical coppers (4.1 +/- 1.0 and 4.2 +/- 1.5 wt.% As, respectively). However, few awls and a dagger from Torre Velha 3 are among the earliest evidence of bronze in SW Iberia, being dated to the second quarter of the 2nd Millennium BC. These bronzes are similar (9.6 +/- 1.2 wt.% Sn) to LBA alloys suggesting trade with a region with a developed bronze metallurgy. The emergence of bronze. in SW Iberia during the first half of the 2nd Millennium BC points to an earlier introduction or a more rapid expansion than initially assumed. Nevertheless, these arsenical coppers and bronzes display a similar manufacture involving hammering and annealing cycles. A final hammering increased the hardness, which could be higher for bronzes. Arsenical coppers display variable operational conditions often with poorer thermomechanical work as expected from a prehistoric technology. A bronze dagger with silver rivets evidences the prestige value of early bronzes to MBA communities. Similarly, an arsenical copper dagger with silver coloured rivets shows the ability of MBA metallurgists to replicate prestige objects with indigenous knowledge. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,1340247,"MiR-206 regulates neural cells proliferation and apoptosis via Otx2 Abstract: MiR-206 was involved in a series of cellular activities, such as the growth and development of skeletal muscle and the tumorigenesis. MiR-206 was characterized previously as a differentially expressed gene in sodium arsenite (SA)-induced neural tube defects (NTDs) in chick embryos via miRNA microarray analysis. However, the role of miR-206 in the pathological process of nerve cells remained elusive. In this study we found differential expression of miR-206 in SA-treated chick embryos by Northern blot analysis. Ectopic expression of miR-206 inhibited cell proliferation, and promoted cell apoptosis in U343 and SK-N-SH cell by using MTT, Edu Apollo assay and Flow cytometry analysis. Further investigation revealed that miR-206 can interact with 3'-untranslated region (UTR) of Otx2. MiR-206 mimics down-regulated the endogeneous Otx2 expression, whereas the miR-206 inhibitor obviously up-regulated the expression of Otx2. These findings indicate that overexpression of miR-206 promotes cell apoptosis and low expression of miR-206 inhibits cell apoptosis. Otx2 may play an important role in the process of miR-206-mediated cell apoptosis.",
Arsenic,1017506,"Concomitant exposure to arsenic and organophosphates on tissue oxidative stress in rats Abstract: Increased use of organophosphates (OPs) and ever increasing arsenic levels in drinking water and their co-existence in the environment could be potentially hazardous. The present study examines the effects of dichlorvos (DDVP) or monocrotophos (MCP) and sodium meta arsenite, individually or in combination for 16 weeks on variables indicative of hematological and tissue oxidative injury in rats. Co-exposure to DDVP, MCP or arsenic produced significant inhibition of brain and serum AChE levels suggesting synergism. Significant increase in hepatic reactive oxygen species and brain thiobarbituric acid reactive substances was observed in arsenic and OPs exposed animals. Co-exposure to arsenic and OPs exhibited synergism in case of ROS while antagonism was noted in case of TBARS. Serum transaminases increased significantly on exposure to OPs and arsenic suggesting liver injury which was less pronounced in case of co-exposure to DDVP and arsenic. WBC counts too showed less pronounced increase on co-exposure to arsenic with OPs compared to all other exposure. Blood arsenic level decreased on co-exposure to arsenic with OPs. The present study points to some interesting observations regarding interaction between arsenic and organophosphates. While, exposure to arsenic, DDVP and MCP lead to significant oxidative stress, their co-exposure not necessarily produce synergistic effects.",
Arsenic,1252230,"Groundwater arsenic calamity in Bangladesh Abstract: The arsenic-affected areas of West Bengal are lying on a sediment of Younger Deltaic Deposition (YDD). The same sediment extends eastwards towards Bangladesh, covering the aroximate area of 34 districts out of a total of 64 districts in Bangladesh, We suspect that the groundwater of these 34 districts of Bangladesh may be arsenic-contaminated. So far, we have collected 3106 water samples for analysis from 28 out of these 34 districts and in 27 districts 38% of the water samples we had analysed contain arsenic above 0.05 mg/l, Area and population of these 27 districts are 51,000 km(2) and 36 million respectively, Out of these 27 districts, so far, we have surveyed 20 districts for arsenic patients, and in 18 districts we have identified people having arsenical skin lesions such as melanosis, leucomelanosis, keratosis, hyperkeratosis, dorsum, non-petting oedema, gangrene and skin cancer, During our preliminary field survey in 45 arsenic-affected villages in 18 districts, from a random examination of 1630 people, including children, 57.5% have arsenical skin-lesions, While comparing the West Bengal arsenic scenario with the available data of Bangladesh, it appears that Bangladesh's arsenic calamity may be more severe, If our prediction that the ground-water of Bangladesh's 34 district is likely to be arsenic-contaminated comes true, then more than 50 million people would be at risk, To combat the situation, Bangladesh needs a proper utilization of its vast surface and rain water resources, Proper watershed management is required urgently.",
Arsenic,668365,"Cell-cycling effects from in vitro exposure to sodium arsenite on developing rat midbrain cells Abstract: Arsenic and its metabolites distribute to all organs in the body, and can pass through the placental barrier as well as the blood brain barrier, which is not fully developed in the fetus. High-dose exposure to arsenic during development has resulted in neural tube defects, exencephaly, and other defects, while molecular mechanisms of lower-dose effects are undefined. In this study, gestation day 12 primary rat midbrain neuroepithelial cells were exposed to sodium arsenite (0, 2, 2.5, 4, and 5 uM, 0-48 hr) in vitro. Cell-cycling effects were determined by continuous BrdU labeling and bivariate flow cytometric Hoechst-ethidium bromide analysis. We observed a time- and concentration-dependent inhibition of cell proliferation in both G1 and G2/M as early as 12 hours after sodium arsenite exposure at the lowest concentration tested (2 uM), with no associated cytotoxicity at 24 hours as shown by the neutral red assay. Because of the observed G1- and G2/M-phase effects, fewer cells entered DNA synthesis or completing one round of cell division, respectively. The magnitude of this effect increased with increasing arsenic concentration. Althoueh cell proliferation was inhibited, cell cycle progression was observed to occur under all exposure conditions.",
Arsenic,627160,"Urinary arsenic and porphyrin profile in C57BL/6J mice chronically exposed to monomethylarsonous acid (MMAIII) for two years Abstract: Arsenicals are proven carcinogens in humans and it imposes significant health impacts on both humans and animals. Recently monomethylarsonous acid (MMA(III)), the toxic metabolite of arsenic has been identified in human urine and believed to be more acutely toxic than arsenite and arsenate. Arsenic also affects the activity of a number of haem biosynthesis enzymes. As a part of 2-year arsenic carcinogenicity study, young female C57BL/6J mice were given drinking water containing 0, 100, 250 and 500 microg/L arsenic as MMA(III)ad libitum. 24 h urine samples were collected at 0, 1, 2, 4, 8 weeks and every 8 weeks for up to 104 weeks. Urinary arsenic speciation and porphyrins were measured using HPLC-ICP-MS and HPLC with fluorescence detection respectively. DMA(V) was a major urinary metabolite detected. Significant dose-response relationship was observed between control and treatment groups after 1, 4, 24, 32, 48, 56, 88, 96 and 104 weeks. The level of uroporphyrin in 250 and 500 microg As/L group is significantly different from the control group after 4, 8, 16, 32, 56, 72, 80, 96 and 104 weeks. Coproporphyrin I level in 500 microAs/L group is significantly different from control group after 8, 24, 32, 40, 56, 72, 80, 88 and 104 weeks. After 4 weeks the level of coproporphyrin III concentration significantly increased in all the treatment groups compared to the control except week 16 and 48. Our results show urinary DMA(V) and porphyrin profile can be used as an early warning biomarker for chronic MMA(III) exposure before the onset of cancer.",
Arsenic,1024750,"Enhanced arsenic accumulation by engineered yeast cells expressing Arabidopsis thaliana phytochelatin synthase Abstract: Phytochelatins (PCs) are naturally occurring peptides with high-binding capabilities for a wide range of heavy metals including arsenic (As). PCs are enzymatically synthesized by phytochelatin synthases and contain a (gamma-Glu-Cys)(n) moiety terminated by a Gly residue that makes them relatively proteolysis resistant. In this study, PCs were introduced by expressing Arabidopsis thaliana Phytochelatin Synthase (AtPCS) in the yeast Saccharomyces cerevisiae for enhanced As accumulation and removal. PCs production in yeast resulted in six times higher As accumulation as compared to the control strain under a wide range of As concentrations. For the high-arsenic concentration, PCs production led to a substantial decrease in levels of PC precursors such as glutathione (GSH) and gamma-glutamyl cysteine (gamma-EC). The levels of As(III) accumulation were found to be similar between AtPCS-expressing wild type strain and AtPCS-expressing acr3Delta strain lacking the arsenic efflux system, suggesting that the arsenic uptake may become limiting. This is further supported by the roughly 1:3 stoichiometric ratio between arsenic and PC2 (n = 2) level (comparing with a theoretical value of 1:2), indicating an excess availability of PCs inside the cells. However, at lower As(III) concentration, PC production became limiting and an additive effect on arsenic accumulation was observed for strain lacking the efflux system. More importantly, even resting cells expressing AtPCS pre-cultured in Zn(2+) enriched media showed PCs production and two times higher arsenic removal than the control strain. These results open up the possibility of using cells expressing AtPCS as an inexpensive sorbent for the removal of toxic arsenic.",
Arsenic,627840,"Evidence for arsenic as the immunosuppressive component of gallium arsenide Abstract: Gallium arsenide (GaAs) has been shown previously to suppress the in vivo antibody-forming cell (AFC) response to sheep erythrocytes (SRBC) when administered intratracheally at concentrations between 50 and 200 mg/kg. In the present studies, direct addition of GaAs to in vitro-generated antibody cultures resulted in dose-dependent suppression of the primary antibody response, and was only seen when GaAs was added within 36 hr following immunization. Using atomic absorption spectrophotometry on tissue samples from mice exposed to 200 mg/kg GaAs, arsenic concentrations were found to peak in the spleen at 24 hr and decline, whereas gallium concentrations continue to rise through 14 days. Concentrations of each metal in the spleen at 24 hr are comparable to the concentrations achieved for each metal when GaAs is added at 25 microM to the in vitro model system. The 24 hr time point was chosen for comparison because all in vivo-in vitro studies were conducted using spleens from mice 24 hr after GaAs exposure. NaAsO2 and Ga(NO3)3 suppressed the AFC response dose-dependently, and in a time-dependent manner similar to GaAs when added to the in vitro system. However, based on IC50 values for each salt, the role of the gallium component in the immunosuppression appears weak. Oxalic acid (OA) and meso-2,3-dimercaptosuccinic acid (DMSA), chelators of gallium and arsenic respectively, were added to cultures with GaAs to confirm that arsenic was the primary immunosuppressive component. DMSA dose-dependently blocked GaAs-induced immunosuppression in vitro, while OA had no effect. The metal-binding compounds were determined to be specific for the metals used in these studies and did not cross-react with one another. DMSA was evaluated for its ability to prevent suppression of the AFC response in splenocytes from GaAs-exposed mice and was able to block GaAs-induced suppression of the AFC response when given sc every 4 hr beginning 1 hr prior to GaAs exposure. These data indicate that the arsenic component of GaAs is the major contributor to the GaAs-induced immunosuppression and that this effect occurs within the first 36 hr of the 5-day culture period in a concentration-dependent manner.",
Arsenic,1341489,"Colorimetric assay for the quantification of serum iodixanol concentration and its application on estimation of glomerular filtration rate in cattle Abstract: A colorimetric assay used to quantify the non-ionic contrast medium iodixanol in sera was validated and compared with high-performance liquid chromatography. The application of this assay to estimate glomerular filtration rates (GFR) in cattle was examined. Serum iodixanol was de-iodinated by alkaline hydrolysis and the amount of released iodine was subsequently determined using a ceric arsenite method. There was a close correlation between the two methods using identical specimens. In clinically healthy cattle with different body weights, the reference value (166.3-178.8 mL/min/m(2)) based on body surface area was fairly stable as compared with that (2.13-3.63 mL/min/kg) based on body weight. Based on GFR data in healthy and renal-impaired cattle, when the GFR decreased to more than 60% of the reference value, serum urea nitrogen and creatinine concentrations increased. The colorimetric assay is a simple method for the estimation of GFR in cattle and requires no expensive equipment.",
Arsenic,1351815,"Left ventricular diastolic function in workers occupationally exposed to mercury vapour without clinical presentation of cardiac involvement Abstract: The aim of the study was to evaluate left ventricular diastolic function in workers occupationally exposed to mercury vapour without clinical presentation of cardiac involvement. The studies included 115 workers (92 men and 23 women) occupationally exposed to mercury vapour without clinical presentation of cardiac involvement (mean age: 47.83±8.29). Blood samples were taken to determine blood lipid profile, urine was collected to estimate mercury concentration (HgU) and echocardiographic examination was performed to evaluate diastolic function of the left ventricle. In the entire group of workers occupationally exposed to mercury vapour without clinical presentation of cardiac involvement, Spearman correlations analysis demonstrated the following significant linear relationships: between body mass index (BMI) and ratio of maximal early diastolic mitral flow velocity/early diastolic mitral annular velocity (E/E`) (r=0.32, p&lt;0.05), between serum HDL concentration and E/E` (r=-0.22, p&lt;0.05), between HgU and E/E` (r=0.35, p&lt;0.05), between HgU and isovolumetric relaxation time (IVRT`) (r=0.41, p&lt;0.05), between HgU and ratio of maximal early diastolic mitral flow velocity/maximal late diastolic mitral flow velocity (E/A) (r=-0.31, p&lt;0.05) and between serum HDL concentration and E/A (r=0.43, p&lt;0,05). In logistic regression analysis it as shown that independent factors of left ventricular diastolic dysfunction risk in the study group included a higher urine mercury concentration, a higher value of BMI and a lower serum HDL concentration (OR(Hg-U)=1.071, OR(BMI)=1.200, OR(HDL)=0.896, p&lt;0.05). Summing up, occupational exposure to mercury vapour may be linked to impaired left ventricular diastolic function in workers without clinical presentation of cardiac involvement.",
Arsenic,1019144,"72-kDa stress protein (hsp72) induced by administration of dimethylarsinic acid to mice accumulates in alveolar flat cells of lung, a target organ for arsenic carcinogenesis Abstract: Our previous studies have demonstrated that the oral administration of dimethylarsinic acid (DMA), a main metabolite of inorganic arsenics in mammals, in mice causes DNA damage in the lung as well as the promotion and progression of lung- and skin-tumorigenesis. Moreover, we indicated that 72-kDa stress protein (Hsp72) was induced in cultured human pulmonary (L-132) cells by exposure to DMA and was accumulated specifically in the cell nuclei. The present in vivo study reveals the induction of Hsp72 by intraperitoneal administration of DMA to A/J mice used previously as an animal model of dimethylarsenic-induced lung tumorigenesis. The Hsp72 was observed in the lung, a target organ for arsenic carcinogenesis in human, and in the kidney as well, but not in the liver and spleen. By immunohistochemical analysis, the Hsp72 in lungs was exhibited to exist in the nuclei of alveolar flat cells, including capillary endothelial cells, which were previously found to increase the clumping of heterochromatin, an early morphological change in the developmental process of pulmonary carcinomas, after administration of DMA to mice. These in vivo observations suggest that the increase and accumulation of Hsp72 by administration of DMA to mice may occur specifically in target organs for arsenic carcinogenesis.",
Arsenic,1348867,"Study of sodium arsenite induced biochemical changes on certain biomolecules of the freshwater catfish Clarias batrachus Abstract: Toxic impact of sublethal concentration (1 mg/L; 5% of 96h LC50 value) of sodium arsenite (NaAsO2) on certain biomolecules (proteins, nucleic acids, lipids, and glycogen) of five tissue components (muscles, liver, brain, skin, and gills) of the freshwater catfish Clarias batrachus was analysed. The important toxic manifestations include marked decrease in the concentration of proteins (21.72-45.42% in muscles; 3.42-53.94% in liver; 15.39-45.42% in brain; 15.40-4.00% in skin and 11.35-64.13% in gills), DNA (0.55-22.95% in muscles; 8.33-14.06% in liver; 5.30-18.40% in brain; 13.57-52.80% in skin; and 12.38-31.01% in gills), RNA (42.68-76.16% in muscles; 10.68-39.75% in liver; 5.66-29.05% in brain; 7.72-27.93% in skin and 21.47-44.38% in gills) and glycogen (24.00-51.72% in muscles; 49.11-72.45% in liver; 11.49-26.03% in brain; 26.13-38.05% in skin and 17.80-37.97% in gills). Excepting liver where the lipid content increases (15.82-24.13%), the fat content also showed depletion in their concentration (10.40-29.83% in muscles; 8.30-34.45% in brain; 8.94-31.47% in skin and 12.75-28.86% in gills), in the rest of the organ systems.",
Arsenic,1019205,"Induction of mitosis-mediated apoptosis by sodium arsenite in HeLa S3 cells Abstract: Arsenic has been used effectively as a chemotherapeutic drug for the treatment of acute promyelocytic leukemia patients. Numerous studies have demonstrated that arsenic induces apoptosis in various cell types. In the present study, we showed that approximately 35% of arsenite-treated HeLa S3 cells arrested in mitosis. After release from arsenite treatment, more than 80% of arsenite-arrested mitotic cells subsequently underwent apoptosis, as indicated by anachronistic nuclear envelope reformation, DNA ladder occurrence, chromatin condensation, and activation of caspases 3 and 9. In exploring how these cells entered apoptosis mechanistically, we found an inverse correlation between mitotic indexes and apoptotic frequencies. As shown by using Percoll density gradient fractionation and flow cytometric analysis, the mitosis-mediated apoptosis induced by arsenite was accompanied by delayed cyclin B degradation and altered mitotic exit. Furthermore, treatment of arsenite-arrested mitotic cells with staurosporine or 2-aminopurine resulted in a rapid degradation of cyclin B, moved these cells forward to interphase without cell division, and abrogated apoptosis. These results suggest that apoptosis occurs in arsenite-arrested mitotic cells that exit mitosis abnormally.",
Arsenic,2345821,"Comprehensive Hemodynamic Comparison and Frequency of Patient-Prosthesis Mismatch between the St. Jude Medical Trifecta and Epic Bioprosthetic Aortic Valves Abstract: Background: Patient-prosthesis mismatch (PPM) has been reported with a wide range of bioprosthetic valves after aortic valve replacement (AVR) and has been associated with multiple adverse outcomes. The aim of this study was to test the hypothesis that a novel low-profile stented pericardial tissue bioprosthesis for AVR, the Trifecta aortic valve, would have superior hemodynamics, a lower incidence of PPM, and an improvement in clinical outcomes. Its hemodynamic performance was evaluated, and a comparison was performed with a traditional stented pericardial bioprosthesis (Epic) with respect to hemodynamics, PPM, and clinical events. <br> <br>Methods: One hundred twenty-four patients (mean age, 73.6 +/- 11.0 years) underwent AVR. Prosthetic valve types used were Trifecta (n = 75 [60.5%]) and Epic (n = 49 [39.5%]). Intraoperative transesophageal echocardiography was used to evaluate hemodynamic variables before and after AVR. <br> <br>Results: Postoperative comparison of the Epic valve and the Trifecta valve revealed a lower mean pressure gradient (16.5 +/- 6.7 vs 8.8 +/- 3.4 mm Hg, P &lt; .001), a lower peak gradient (33.3 +/- 11.8 vs 19.4 +/- 8.6 mm Hg, P &lt; .001), and higher indexed effective orifice area (0.8 +/- 0.2 vs 1.1 +/- 0.4 cm(2)/m(2), P &lt; .001), favoring the Trifecta valve across several valve sizes. Severe PPM (6% vs 27%, P &lt; .001) and valvular-related complications at follow-up (14.3% vs 36.7%, P = .005) were less frequent in the Trifecta group. <br> <br>Conclusions: The hemodynamic performance of the Trifecta valve is superior to that of the Epic valve across many conventional prosthesis sizes, and its implantation resulted in lower rates of severe PPM. These improvements were associated with lower valvular-related adverse events.",
Arsenic,627481,"NADH oxidase activation is involved in arsenite-induced oxidative DNA damage in human vascular smooth muscle cells Abstract: Arsenic is atherogenic, carcinogenic, and genotoxic. Because atherosclerotic plaque has been considered a benign smooth muscle cell tumor, we have studied the effects of arsenite on DNA integrity of human vascular smooth muscle cells. By using single-cell alkaline electrophoresis, apparent DNA strand breaks were detected in a 4-hour treatment with arsenite at a concentration above 1 mmol/L. DNA strand breaks of arsenite-treated cells were increased by Escherichia coli formamidopyrimidine–DNA glycosylase and decreased by diphenylene iodinium, superoxide dismutase, catalase, pyruvate, DMSO, or D-mannitol. Extract from arsenite-treated cells showed increased capacity for producing superoxide when NADH was included in the reaction mixture; however, addition of arsenite to extract from untreated cells did not increase superoxide production. The superoxide-producing ability of arsenite-treated cells was also suppressed by diphenylene iodinium, 4,5-dihydroxy-1,2-benzenedisulfonic acid disodium salt (Tiron), or superoxide dismutase. Superoxide production and DNA strand breaks in arsenite-treated cells were also suppressed by transfecting antisense oligonucleotides of p22phox, an essential component of NADH oxidase. Treatment with arsenite also increased the mRNA level of p22phox. These results suggest that arsenite activates NADH oxidase to produce superoxide, which then causes oxidative DNA damage. The result that arsenite at low concentrations increases oxidant levels and causes oxidative DNA damage in vascular smooth muscle cells may be important in arsenic-induced atherosclerosis.",
Arsenic,2347703,"Degradation of roxarsone in a silt loam soil and its toxicity assessment Abstract: The land application of poultry or swine litter, containing large amounts of roxarsone, causes serious arsenic pollution in soil. Understanding biotransformation process of roxarsone and its potential risks favors proper disposal of roxarsone-contaminated animal litter, yet remains not achieved. We report an experimental study of biotransformation process of roxarsone in a silt loam soil under various soil moisture and temperature conditions, and the toxicity of roxarsone and its products from degradation. Results showed that soil moisture and higher temperature promoted roxarsone degradation, associating with emergent pentavalent arsenic. Analysis of fluorescein diacetate (FDA) hydrolysis activity revealed that roxarsone does not exert acute toxic on soil microbes. With the release of inorganic arsenic, FDA hydrolysis activity was inhibited gradually, as evidenced by ecotoxicological assessment using Photobacterium leiognathi. The results shade new lights on the dynamic roxarsone biotransformation processes in soil, which is important for guiding appropriate disposal of poultry or swine litter in the environment.",
Arsenic,1022506,"Speciation of arsenic in human nail and hair from arsenic-affected area by HPLC-inductively coupled argon plasma mass spectrometry Abstract: Nail and hair are rich in fibrous proteins, i.e., alpha-keratins that contain abundant cysteine residues (up to 22% in nail and 10-14% in hair). Although they are metabolically dead materials in the epidermis, the roots are highly influenced by the health status of the living beings and their analyses are used as a tool to monitor occupational and environmental exposure to toxic elements. The aims of the present study are to speciate arsenicals in human nail and hair and also to judge whether they should be used as a biomarker to arsenic (As) exposure and/or toxicity. All human fingernail and hair samples (n = 47) were collected from the As-affected area of West Bengal, India. Speciation of arsenicals in water extracts of fingernails and hair at 90 degrees C was carried out by HPLC-inductively coupled argon plasma mass spectrometer (ICP MS). Fingernails contained iAs(III) (58.6%), iAs(V) (21.5), MMA(V) (7.7), DMA(III) (9.2), and DMA(V) (3.0), and hair contained iAs(III) (60.9%), iAs(V) (33.2), MMA(V) (2.2), and DMA(V) (3.6). Fingernails contained DMA(III), but hair did not. The higher percentage of iAs(III) both in fingernails and hair than that of iAs(V) suggests more affinity of iAs(III) to keratin. Although all arsenicals in fingernails and hair correlate to As exposure positively, As speciation in fingernails seems to be more correlated with arsenism than that in hair. Exogenous contamination is a confounding factor for hair to consider it as a biomarker, whereas this is mostly absent in fingernails, which recommends it to be a better biomarker to arsenic exposure. DMA(III) content in fingernails and DMA(V) contents in both fingernails and hair could be the biomarker to As exposure.",
Arsenic,2064228,"A Dose-Response Study of Arsenic Exposure and Global Methylation of Peripheral Blood Mononuclear Cells in Bangladeshi Adults Abstract: <strong>BACKGROUND: </strong>Several studies employing cell culture and animal models suggest that arsenic (As) exposure induces global DNA hypomethylation. However, As has been associated with global DNA hypermethylation in human study populations. It has been hypothesized that this discrepancy may reflect a non-linear relationship between As dose and DNA methylation.<br /><br /><strong>OBJECTIVE: </strong>The objective of this study was to examine the dose-response relationship between As and global methylation of peripheral blood mononuclear cell (PBMC) DNA in apparently healthy Bangladeshi adults chronically exposed to a wide range of As concentrations in drinking water.<br /><br /><strong>METHODS: </strong>Global PBMC DNA methylation, plasma folate, blood S-adenosylmethionine (SAM), and concentrations of As in drinking water, blood, and urine were measured in 320 adults. DNA methylation was measured using the [(3)H]-methyl incorporation assay, which provides disintegration per minute (DPM) values that are negatively associated with global DNA methylation.<br /><br /><strong>RESULTS: </strong>Water, blood, and urinary As were positively correlated with global PBMC DNA methylation (P &lt; 0.05). In multivariable adjusted models, 1-µg/L increases in water and urinary As were associated with 27.6 unit (95% CI, 6.3 to 49.0) and 22.1 unit (95% CI, 0.5 to 43.8) decreases in DPM per µg DNA, respectively. Categorical models indicated that estimated mean levels of PBMC DNA methylation were highest in participants with the highest As exposures.<br /><br /><strong>CONCLUSIONS: </strong>These results suggest that As is positively associated with global methylation of PBMC DNA over a wide range of drinking water As concentrations. Further research is necessary to elucidate underlying mechanisms and physiologic implications.?",
Arsenic,2149084,"Beyond regulations: Industry voluntary ban in arsenic use Abstract: Firms play a key role in pollution abatement and control by engaging in beyond-compliance actions without the force of law in voluntary programs. This study examines the effectiveness of a bilateral voluntary agreement, one type of voluntary programs, negotiated between the U.S. Environmental Protection Agency (EPA) and the pressure-treated wood industry to phase-out the use of chromated copper arsenate (CCA), a poisonous arsenic compound. Arsenic is ranked number one on the EPA's priority list of hazardous substances. Unlike a majority of earlier studies on voluntary programs, dynamic panel estimation and structural break analysis show that while a technological innovation in semiconductors is associated with arsenic use increases, the CCA voluntary agreement is associated with a reduction in arsenic use to levels not seen since the 1920s. A voluntary ban in arsenic acid by pesticide manufacturers in the agriculture sector has also contributed to arsenic reductions. Furthermore, the results suggest that environmental activism has played a role in curbing arsenic use. Increasing stakeholder pressures, as measured by membership in the Sierra Club, improves voluntary agreement effectiveness.",
Arsenic,1375317,"The evaluation of carcinogenic risk to humans: Occupational exposures in the spraying and application of insecticides Abstract: BIOSIS COPYRIGHT: BIOL ABS. The International Agency for Research on Cancer (IARC) has reviewed the carcinogenic risk to man of the occupation of spraying or applying insecticides. IARC was unable to conclude that a causal relationship had been established (category 1), but there was some evidence which led them to consider the occupation to be probably carcinogenic (in category 2A). These conclusions have been reviewed by a working group of the International Group of National Associations of Manufacturers of Agrochemical Products (GIFAP) to determine what steps needed to be taken which might improve safety for those working with insecticides. The working group reinforced the view that a causal relationship could not be established. In addition, the usage rate of insecticides has decreased since the time of the studies that IARC considered, their general toxicity has decreased, and the products themselves have been the subject of close regulatory scrutiny. It is considered that these changes are a",
Arsenic,1579392,"A methodology for spatially representing the likelihood of occurrence of natural contaminants in groundwater Abstract: This paper presents a novel method of spatially representing the likelihood of occurrence of a contaminant in groundwater at the scale of a municipality or watershed. The specific contaminant of concern in the case study area is arsenic, which is variably present in groundwater at concentrations exceeding the 10 µg/l drinking water guideline. The method used to produce the likelihood of occurrence map incorporates confidence of geochemical interpretation based on availability of information and data on each aquifer. While demonstrated using arsenic as the contaminant of interest, the approach is readily adapted to other groundwater constituents. The final map is intended to be of use to water managers as it provides a spatial representation of aquifers of concern and identifies areas where further sampling or monitoring may be needed.",
Arsenic,1028835,"Assessment of exposure to arsenic among smelter workers: A five-year follow-up Abstract: In a group of 43 smelter workers exposed to inorganic arsenic dust for 13-45 years, nerve conduction velocities (NCVs) were significantly lower in two peripheral nerves as compared with matching referents. With multivariate data analysis, a significant negative correlation was found between cumulative absorption of arsenic and NCV in four examined nerves and the sural amplitude. Clinical symptoms of neuropathy and other symptoms related to arsenic exposure were moderate, though the difference between the groups was significant. The mean total absorption of arsenic was calculated to be less than 5 g, and the maximal absorption about 20 g. These data indicate that the adverse effect of arsenic on the peripheral nerves is dependent on long-term exposure rather than on short-term fluctuations in exposure levels.",
Arsenic,386195,"Lead induces the expression of ER chaperones GRP78 and GRP94 in vascular endothelial cells via the JNK-AP-1 pathway Abstract: Lead, a ubiquitous heavy metal, is an important industrial and environmental pollutant that can target the vascular endothelium. To clarify the effects of lead on the unfolded protein response (UPR) and their significance in cytotoxicity, we examined the expression and function of endoplasmic reticulum (ER) chaperones glucose-regulated protein 78 (GRP78) and 94 (GRP94) in vascular endothelial cells. We used bovine aortic endothelial cells as an in vitro model of the vascular endothelium. Exposure of vascular endothelial cells to lead nitrate resulted in a marked induction of GRP78 and GRP94 mRNA levels. In response to lead, the expression of GRP78 and GRP94 proteins also significantly increased in a dose- and time-dependent manner. In addition, siRNA-mediated knockdown of GRP78 significantly enhanced lead-induced cytotoxicity. Compared with other metal(loid)s, including cadmium chloride, zinc sulfate, copper sulfate, and sodium arsenite, lead nitrate was found to be the most potent metal to induce these chaperones in endothelial cells. In the examined UPR pathways, lead increased the phosphorylation of IRE1 and JNK. Interestingly, the lead-induced upregulation of GRP78 and GRP94 was almost completely blocked by the JNK inhibitor SP600125 or AP-1 inhibitor curcumin. Taken together, these results suggest that lead induces ER stress, but the induction of GRP78 and GRP94 expression via the JNK-AP-1 pathway functions as a defense mechanism against lead-induced cytotoxicity in vascular endothelial cells.",
Arsenic,493075,"Human macrophages constitute targets for immunotoxic inorganic arsenic Abstract: Chronic exposure to inorganic arsenic, a widely distributed environmental contaminant, can lead to toxic effects, including immunosuppression. Owing to the established roles of human macrophages in immune defense, we determined, in the present study. whether inorganic arsenic can affect these major immune cells. Our results demonstrate that noncytotoxic concentrations of arsenic trioxide (As2O3), an inorganic trivalent form, markedly impair differentiated features of human blood monocyte-derived macrophages. First, treatment of macrophages with 1 mu M As2O3 induced a rapid cell rounding and a subsequent loss of adhesion. These morphologic alterations were associated with a marked reorganization of actin cytoskeleton, which includes retraction of peripheral actin extensions and formation of a cortical actin ring. In addition, AS(2)O(3) reduced expression of various macrophagic surface markers, enhanced that of the monocytic marker CD14, and altered both endocytosis and phagocytosis; unexpectedly, exposure of macrophages to the metalloid also strongly potentiated expression of TNF alpha and IL-8 induced by LPS. Finally, like monocytes, As2O3-treated macrophages can be differentiated into dendritic-like cells. Impairment of macrophage function by As2O3 mainly resulted from activation of a RhoA/Rho-associated kinase pathway; indeed, pretreatment of macrophages with the Rho-associated kinase inhibitor Y-27632 prevented metalloid effects on cytoskeleton and phagocytosis. Moreover, AS(2)O(3) was found to increase level of the active GTP-bound form of RhoA and that of phosphorylated-Moesin, a major cytoskeleton adaptor protein involved in RhoA regulation. Taken together, our results demonstrated that human macrophages constitute sensitive targets of inorganic arsenic, which may contribute to immunotoxicity of this environmental contaminant.",
Arsenic,1508574,"TDP-43 associates with stalled ribosomes and contributes to cell survival during cellular stress Abstract: TAR DNA-binding protein 43 (TDP-43) has emerged as an important contributor to amyotrophic lateral sclerosis and frontotemporal lobar degeneration. To understand the physiological roles of TDP-43 in the complex translational regulation mechanisms, we exposed cultured cells to oxidative stress induced by sodium arsenite (ARS) for different periods of time, leading to non-lethal or sublethal injury. Polysome profile analysis revealed that ARS-induced stress caused the association of TDP-43 with stalled ribosomes via binding to mRNA, which was not found under the steady-state condition. When the cells were exposed to short-term/non-lethal stress, TDP-43 associating with ribosomes localized to stress granules (SGs); this association was transient because it was immediately dissolved by the removal of the stress. In contrast, when the cells were exposed to long-term/sublethal stress, TDP-43 was excluded from SGs and shifted to the heavy fractions independent of any binding to mRNA. In these severely stressed cells, biochemical alterations of TDP-43, such as increased insolubility and disulfide bond formation, were irreversible. TDP-43 was finally phosphorylated via the ARS-induced c-jun N-terminal kinase pathway. In TDP-43-silenced cells, stalled mRNA and poly (A)+ RNA stability was disturbed and cytotoxicity increased under sublethal stress. Thus, TDP-43 associates with stalled ribosomes and contributes to cell survival during cellular stress.",
Arsenic,1519066,"Short And Long-Term Outcomes After Esophagectomy For Cancer In Elderly Patients Abstract: BACKGROUND: As worldwide life expectancy rises, the number of candidates for surgical treatment of esophageal cancer over 70 years will increase. This study aims to examine outcomes after esophagectomy in elderly patients. METHODS: Retrospective review of 474 patients undergoing esophagectomy for cancer during 2002-2011. 334 (70.5%) patients were &lt;70 years old (group A), 124 (26.2%) 70-79 years (group B) and 16 (3.4%) ?80 years (group C). We analyzed the effect of age on outcome variables including overall and disease specific survival. RESULTS: Major morbidity was observed to occur in 115 (35.6%) patients of group A, 58 (47.9%) of group B and 10 (62.5%) of group C (p=0.010). Mortality, both 30- and 90-day was observed in 2(0.6%) and 7(2.2%) of group A, 4(3.2%) and 7 (6.1%) of group B, and 1(6.3%) and 2(14.3%) of group C, respectively (p=0.032 and p=0.013). Anastomotic leak was observed in 16(4.8%) patients of group A, 6(4.8%) of group B and 0(0%) of group C (p=0.685). Anastomotic stricture (defined by the need for ?2 dilations) was observed in 76(22.8%) of group A, 13(10.5%) of group B and 1(6.3%) of group C (p=0.005). Five-year overall and disease specific survival was 64.8% and 72.4% for group A, 41.7% and 53.4% for group B, 49.2% and 49.2% for group C patients (p=0.0006), respectively. CONCLUSIONS: Esophagectomy should be carefully considered in patients 70-79 years old and can be justified with low mortality. Outcomes in octogenarians are worse suggesting esophagectomy be considered on a case by case basis. Stricture rate is inversely associated to age.",
Arsenic,2347799,"Effect of vitamin E supplementation on production performances in arsenic exposed goats Abstract: The present study was designed to investigate the effect of vitamin E supplementation on production performances in arsenic fed goats. Crossbred lactating goats (24) were distributed randomly into 4 equal groups (control, T-1, T-2 and T-3) of 6 in each, on the basis of average body weight (36.10 +/- 0.11 kg) and milk yield (1.61 +/- 0.004 kg/day). The animals in T-1, T-2 and T-3 were given 50 mg/kg dry matter arsenic daily, while in T-2 and T-3, vitamin E @ 100 IU and 150 IU/kg dry matter, respectively, was also supplemented additionally for 12 months. Both the arsenic and arsenic plus vitamin E supplementation, did not show any significant effect on dry matter intake, body weight and milk yield. Milk Cu, Zn and vitamin E level remain unaffected due to dietary treatments. Except control, in all arsenic exposed groups, milk arsenic level increased and vitamin E in higher doses showed comparatively less increase in milk arsenic level. It can be concluded from the present study that arsenic exposure in goats resulted no changes in production performances, milk Cu, Zn and vitamin E level but increases the milk arsenic level and concomitant treatment with vitamin E is helpful in reducing the burden of arsenic in milk.",
Arsenic,1508570,"Arsenic geochemistry in a biostimulated aquifer: An aqueous speciation study Abstract: Stimulating microbial growth through the use of acetate injection wells at the former uranium mill site in Rifle, CO has been shown to decrease dissolved uranium (VI) concentrations through bacterial reduction to immobile U(IV). Bioreduction also changed the redox chemistry of site groundwater altering the mobility of several other redox sensitive elements present in the subsurface, including iron, sulfur, and arsenic. Following acetate amendment at the site, elevated concentrations of arsenic in groundwater were observed. Ion chromatography coupled to inductively coupled plasma - mass spectrometry (IC-ICP-MS) was used to determine the aqueous arsenic speciation. Upgradient samples, unexposed to acetate, showed low levels of arsenic (?1 uM) with greater than 90% as arsenate (As V) and a small amount of arsenite (As III). Downgradient acetate-stimulated water samples had much higher levels of arsenic (up to 8 uM), and four additional thioarsenic species were present under sulfate reducing conditions. These thioarsenic species demonstrate a strong correlation between arsenic release and sulfide concentrations in groundwater and their formation may explain the elevated total arsenic concentrations. An alternative approach, enhanced flushing of uranium, was accomplished by addition of bicarbonate, and did not result in highly-elevated arsenic concentrations. Environ. Toxicol. Chem. © 2013 SETAC.",
Arsenic,1015883,"Effects of calcium peroxide on arsenic uptake by celery (Apium graveolens L.) grown in arsenic contaminated soil Abstract: The ability of calcium peroxide (CaO(2)) to immobilize As of contaminated soil was studied using pot and field experiments. In pot experiment, CaO(2) applied at 2.5 and 5gkg(-1) significantly increased celery shoot weight and decreased shoot As accumulation, which was ascribed to the formation of stable crystalline Fe and Al oxides bound As and the reduction of labile As fractions in the soil. The labile As fractions were pH dependent and it followed a &quot;V&quot; shaped profile with the change of pH. In field experiment, the dose of CaO(2) application at 750kgha(-1) was optimal and at which the celery was found to produce the highest biomass (63.4Mgha(-1)) and lowest As concentration (0.43mgkg(-1)). CaO(2) probably has a promising potential as soil amendment to treat As contaminated soils.",
Arsenic,1347296,"Adsorption of arsenate and arsenite from aqueous solutions by cerium-loaded cation exchange resin Abstract: The removal of arsenic from water and wastewater is obligatory. Resin is one of the most effective adsorbents for the removal of arsenic. In order to improve the adsorption capacity of resin, a new cerium-loaded cation exchange resin arsenic adsorbent was prepared by impregnating cerium into the cation exchange resin. Batch adsorption experiments under various conditions, such as time, temperature, pH and with coexisting ions were carried out to evaluate the adsorption characteristics of cerium-loaded resin in the removal of As(V) and As(III) from aqueous solutions. The results showed that the adsorption kinetics of As(V) and As(III) obeyed a pseudo second-order kinetic model and the adsorption rate constants were 0.3159 and 0.5215 g·mg?1·min?1, respectively. The adsorption of As(V) followed the Freundlich adsorption isotherm model and the adsorption isotherm data for As(III) fitted well to the Langmuir equation model. The adsorption capacities were 1.0278 mg/g for As(V) and 2.5297 mg/g for As(III). Both the adsorption of As(V) and As(III) were found to be pH sensitive and the optimum pH was found to be 5-6. Except for the phosphate ion, the coexisting anionics, such as nitrate, chlorate, sulphate and carbonate, showed no remarkable effect on As(V) and As(III) adsorption. The desorption and regeneration study showed that the adsorption capacity of Ce-loaded resin for As(V) and As(III) could be restored to 97.80% and 69.61%, respectively, using 0.5 mol/L sodium hydroxide solution.",
Arsenic,1340002,"Evaluation of the male reproductive toxicity of gallium arsenide Abstract: Gallium arsenide is an important semiconductor material marketed in the shape of wafers and thus is not hazardous to the end user. Exposure to GaAs particles may, however, occur during manufacture and processing. Potential hazards require evaluation. In 14-week inhalation studies with small GaAs particles, testicular effects have been reported in rats and mice. These effects occurred only in animals whose lungs showed marked inflammation and also had hematologic changes indicating anemia and hemolysis. The time- and concentration-dependent progressive nature of the lung and blood effects together with bioavailability data on gallium and arsenic lead us to conclude that the testicular/sperm effects are secondary to hypoxemia resulting from lung damage rather than due to a direct chemical effect of gallium or arsenide. Conditions leading to such primary effects are not expected to occur in humans at production and processing sites. This has to be taken into consideration for any classification decision for reproductive toxicity; especially a category 1 according to the EU CLP system is not warranted.",
Arsenic,1339275,"Magnetite/mesocellular carbon foam as a magnetically recoverable fenton catalyst for removal of phenol and arsenic Abstract: A magnetite-loaded mesocellular carbonaceous material, Fe3O4/MSU-F-C, exhibited superior activity as both a Fenton catalyst and an adsorbent for removal of phenol and arsenic, and strong magnetic property rendering it separable by simply applying magnetic field. In the presence of hydrogen peroxide, the catalytic process by Fe3O4/MSU-F-C completely oxidized phenol and As(III) under the conditions where commercial iron oxides showed negligible effects. Notably, the decomposition of H2O2 by Fe3O4/MSU-F-C was not faster than those by commercial iron oxides, indicating that hydroxyl radical produced via the catalytic process by Fe3O4/MSU-F-C was used more efficiently for the oxidation of target contaminants compared to the other iron oxides. The homogeneous Fenton reaction by the dissolved iron species eluted from Fe3O4/MSU-F-C was insignificant. At relatively high doses of Fe3O4/MSU-F-C, total concentration of arsenic decreased to a significant extent due to the adsorption of arsenic on the catalyst surface. The removal of arsenic by adsorption was found to proceed via preoxidation of As(III) into As(V) and the subsequent adsorption of As(V) onto the catalyst.",
Arsenic,1022523,"Arsenite-induced formation of hydroxyl radical in the striatum of awake rats Abstract: Recent studies on the mechanisms of arsenite toxicity report that some of its effects have been traced to the generation of reactive oxygen species during oxidative stress. In this study we analyze the formation of hydroxyl radicals in the brain of awake, freely moving rats, in order to obtain direct evidence of arsenic-induced oxidative stress in this tissue. We examined the time-course of hydroxyl radical formation in the striatum of both female and male rats who underwent a direct infusion during 60 min of different concentrations of arsenite in that structure through a microdialysis probe. We report here that basal levels of hydroxyl radical production in female rats are significantly higher than those in male rats (91.9+/-16.1 vs. 59.2+/-18.1 pmol/ml, P&lt;0.001) and that the treatment with arsenite induced significant increases of hydroxyl radical formation over basal levels at 50, 100, 200 and 400 microM (95, 98, 98 and 99% increases, respectively, P&lt;0.05 in all cases). The maximal response to 100 microM arsenite is significantly higher in female than in male rats (194.6+/-50.1 female rats and 88.1+/-11.6 pmol/ml male rats, P=0.036). These results support the participation of hydroxyl radicals in arsenic-induced disturbances in the central nervous system.",
Arsenic,1579303,"Occupational exposure to arsenic and risk of non-melanoma skin cancer in a multinational European study Abstract: Occupational studies show a high risk of lung cancer related to arsenic exposure by inhalation; however, only a few studies, and with conflicting results, previously examined a potential link between arsenic exposure at work and skin cancer. The aim of this study is to assess airborne arsenic exposures at the workplace and to quantify associations with non-melanoma skin cancer (NMSC). The study sample consists of 618 incident cases of NMSC and 527 hospital-based controls aged 30-79 years from Hungary, Romania, and Slovakia. Exposures were evaluated by local experts using occupational histories. Information on host factors and other exposures was collected and employed to adjust the associations of interest using multivariable logistic regression. The lifetime prevalence of exposure to work-related arsenic is 23.9% for cases and 15.5% for controls. We do not detect a significant association between arsenic exposure in the workplace and NMSC, although an increased adjusted odd ratio is observed for participants with higher cumulative lifetime workplace exposure to arsenic in dust and fumes compared to referents (OR 1.94, 95% CI 0.76-4.95). There is evidence for modification of the workplace arsenic-NMSC association by work-related sunlight exposure in women, with a markedly increased adjusted odds ratio in the presence of workplace sunlight exposure (OR 10.22, 95% CI 2.48-42.07). Workplace co-exposure to arsenic and sunlight may thus pose an increased risk of NMSC. © 2013 Wiley Periodicals, Inc.",
Arsenic,1026468,"Impact of arsenic in foodstuffs on the people living in the arsenic-affected areas of West Bengal, India Abstract: Although the accumulation of arsenic (As) in human blood is linked with some diseases and with occupational exposure, there are few reports on speciation of As in blood. On the basis of our earlier article, elevated level of arsenicals in human urine and blood were found in the ex-exposed population via As-containing drinking water. The aim of the present study was to get an insight on impact of As in foodstuffs on the people living in the As-affected areas. Moreover, speciation of arsenicals in urine, and water-samples found in arsenobetaine (AsB). Since sampling population (n=25) was not taking any seafood, As in foodstuffs was thought to be the prime source for this discrepancy. So, speciation of methanol extract of freeze-dried red blood cells (RBCs) and foodstuffs, and trichloro acetic acid (TCA) treated plasma by high performance liquid chromatography-inductively coupled argon plasma mass spectrometer (HPLC-ICP MS) collected from the study population (n=33) was carried out to support our hypothesis. Results showed that urine contained AsB (1.7%), arsenite (iAs(III)) (14.3), arsenate (iAs(V)) (4.9), monomethylarsonous acid (MMA(III)) (0.64), monomethylarsonic acid (MMA(V)) (13.6), dimethylarsinous acid (DMA(III)) (7.7), and dimethylarsinic acid (DMA(V)) (65.4). Blood contained 21.3 microg L(- 1) (mean) As and of which 27.3% was in plasma and 72.7% in RBCs. RBCs contained AsB (21.6%) and DMA(V) (78.4) and blood plasma contained AsB (12.4%), iAs(III) (25.9), MMA(V) (30.3), and DMA(V) (31.4). Furthermore, speciation of As in foodstuffs showed that most of them contained AsB (3.54-25.81 microg kg(- 1)) (25.81-312.44 microg kg(- 1)) along with iAs(III) (9.62-194.93), iAs(V) (17.63-78.33), MMA(V) (9.47-73.22) and DMA(V) (13.43-101.15) that supported the presence of AsB and elevated As in urine and blood samples of the present study group. Inorganic As (iAs) predominates in rice (67.17-86.62%) and in spices (40-90.35%), respectively over organic As. So, As in the food chain is a real threat to human health.",
Arsenic,711048,"Tissue-Specific and Dose-Related Accumulation of Arsenic in Mouse Offspring Following Maternal Consumption of Arsenic-Contaminated Water Abstract: ? The developmental toxicity of arsenic is not as well characterized as other metals such as lead or mercury. Many previous animal studies have used an acute exposure paradigm, which does not model chronic, low-level human exposure. The following study administered 10, 20, 40, 80 or 100?ppm sodium arsenite in drinking water to pregnant C57BL6/J mice. Adipose, blood, brain, breastmilk in stomach, kidney and liver tissues were collected from male and female offspring on postnatal day (PND) 1 and 21 to allow for disposition comparisons between tissues, sexes and across time. The 100?ppm dose was foetotoxic. Significantly fewer female pups were born in litters exposed to 80?ppm, while significantly more male pups were born in litters exposed to 20?ppm. Total arsenic levels differed between tissues with the highest levels in the brain and kidney in PND1 offspring. Levels were higher on PND1 than PND21, and there were few sex differences. The dose-response relationships in PND1 tissues were curvilinear, but in PND21 liver and kidney tissues, arsenic levels in control animals were significantly higher than levels in exposed animals. The tissue and age-specific disposition suggests that common biomarkers such as blood and urinary arsenic are not accurate predictors of levels in sensitive organs such as the brain.",
Arsenic,2279310,"How does the ascending aorta geometry change when it dissects? Abstract: <strong>OBJECTIVES: </strong>To delineate changes in aortic geometry and diameter due to dissection.<br /><br /><strong>BACKGROUND: </strong>Aortic diameter is the major criterion for elective ascending aortic replacement for dilated ascending aortas to prevent aortic dissection. However, recommendations are based on clinical experience and observation of diameters of previously dissected aortas.<br /><br /><strong>METHODS: </strong>Six tertiary centers on two continents reviewed their acute aortic dissection type A databases, containing 1821 patients. Included were all non-Marfan, non-bicuspid patients who had undergone computed tomography angiography less than 2 years before and immediately after aortic dissection onset. Aortic geometry before and after dissection onset were compared.<br /><br /><strong>RESULTS: </strong>Altogether, 63 patients were included (27/36 spontaneous/retrograde dissections, mean age 68 (57, 77) years, 54% males). In all but one patient maximum ascending aortic diameter was <55mm before aortic dissection onset. The largest increase in diameter and volume induced by the dissection were observed in the ascending aorta (40.1 (36.6, 45.3) versus 52.9 (46.1, 58.6) mm; +12.8 mm, P<0.001; 124.0 (90.8, 162.5) versus 171.0 (147.0, 197.0) cm(3), +47 cm(3), P<0.001). Mean aortic arch diameter increased from 39.8 (30.5, 42.6) to 46.4 (42.0, 51.6) mm (+6.6 mm, P<0.001) and descending thoracic aorta diameter from 31.2 (27.0, 33.3) to 34.9 (30.9, 39.5) mm (+3.7mm, P<0.001). Changes in thoracic aorta geometry were similar for spontaneous and retrograde etiology.<br /><br /><strong>CONCLUSIONS: </strong>Geometry of the thoracic aorta is affected by aortic dissection, leading to increase in diameter, most pronounced in the ascending aorta. Both spontaneous and retrograde dissection result in similar aortic geometry changes.",
Arsenic,1519045,"The complete genome sequence of the plant growth-promoting bacterium Pseudomonas sp. UW4 Abstract: The plant growth-promoting bacterium (PGPB) Pseudomonas sp. UW4, previously isolated from the rhizosphere of common reeds growing on the campus of the University of Waterloo, promotes plant growth in the presence of different environmental stresses, such as flooding, high concentrations of salt, cold, heavy metals, drought and phytopathogens. In this work, the genome sequence of UW4 was obtained by pyrosequencing and the gaps between the contigs were closed by directed PCR. The P. sp. UW4 genome contains a single circular chromosome that is 6,183,388 bp with a 60.05% G+C content. The bacterial genome contains 5,423 predicted protein-coding sequences that occupy 87.2% of the genome. Nineteen genomic islands (GIs) were predicted and thirty one complete putative insertion sequences were identified. Genes potentially involved in plant growth promotion such as indole-3-acetic acid (IAA) biosynthesis, trehalose production, siderophore production, acetoin synthesis, and phosphate solubilization were determined. Moreover, genes that contribute to the environmental fitness of UW4 were also observed including genes responsible for heavy metal resistance such as nickel, copper, cadmium, zinc, molybdate, cobalt, arsenate, and chromate. Whole-genome comparison with other completely sequenced Pseudomonas strains and phylogeny of four concatenated &quot;housekeeping&quot; genes (16S rRNA, gyrB, rpoB and rpoD) of 128 Pseudomonas strains revealed that UW4 belongs to the fluorescens group, jessenii subgroup.",
Arsenic,2088355,Passage determines toxicity and neuronal markers expression in PC12 cells with altered phenotype Abstract: ,
Arsenic,2343483,"A C*As lyase for degradation of environmental organoarsenical herbicides and animal husbandry growth promoters Abstract: Arsenic is the most widespread environmental toxin. Substantial amounts of pentavalent organoarsenicals have been used as herbicides, such as monosodium methylarsonic acid (MSMA), and as growth enhancers for animal husbandry, such as roxarsone (4-hydroxy-3-nitrophenylarsonic acid) [Rox(V)]. These undergo environmental degradation to more toxic inorganic arsenite [As(III)]. We previously demonstrated a two-step pathway of degradation of MSMA to As(III) by microbial communities involving sequential reduction to methylarsonous acid [MAs(III)] by one bacterial species and demethylation from MAs(III) to As(III) by another. In this study, the gene responsible for MAs(III) demethylation was identified from an environmental MAs(III)-demethylating isolate, Bacillus sp. MD1. This gene, termed arsenic inducible gene (arsI), is in an arsenic resistance (ars) operon and encodes a nonheme iron-dependent dioxygenase with C?As lyase activity. Heterologous expression of ArsI conferred MAs(III)-demethylating activity and MAs(III) resistance to an arsenic-hypersensitive strain of Escherichia coli, demonstrating that MAs(III) demethylation is a detoxification process. Purified ArsI catalyzes Fe(2+)-dependent MAs(III) demethylation. In addition, ArsI cleaves the C?As bond in trivalent roxarsone and other aromatic arsenicals. ArsI homologs are widely distributed in prokaryotes, and we propose that ArsI-catalyzed organoarsenical degradation has a significant impact on the arsenic biogeocycle. To our knowledge, this is the first report of a molecular mechanism for organoarsenic degradation by a C?As lyase.",
Arsenic,2064278,"Biomonitoring of cadmium, chromium, nickel and arsenic in general population living near mining and active industrial areas in Southern Tunisia Abstract: The human health impact of the historic and current mining and industrial activities in Tunisia is not known. This study assessed the exposure to metals in the population of Southern Tunisia, using biomonitoring. The aim of this pilot study was to evaluate metal exposure on 350 participants living near mining and active industrial areas in the South of Tunisia. Blood specimens were analyzed for metals (Cd, Cr, As, and Ni) by Atomic Absorption Spectrometer equipped with Zeeman background correction and AS-800 auto sampler by graphite furnace and graphite tubes with integrated L'vov platform. The sample population was classified according to different age groups, sex, smoking habit, sea food and water drinking consumption, occupational exposure, amalgam fillings and place of residence. The blood As, Cd, Cr and Ni values expressed as mean?±?SD were 1.56?±?2.49, 0.74?±?1.15, 35.04?±?26.02 and 30.56?±?29.96 ?g/l, respectively. Blood Cd and Ni levels in smokers were 2 and 1.2 times, respectively, higher than in non-smokers. Blood Cd levels increase significantly with age (p?=?0.002). As, Cd and Ni were significantly correlated with gender and age (p?&lt;?0.05). Cd level in blood samples of subjects occupationally exposed was 1.3 times higher than that of non-exposed. Blood metals were not significantly affected by amalgam fillings, place of living and sea food and drinking water consumption. This first biomonitoring study of metal exposure in the South of Tunisia reveals a substantial exposure to several metals. The pathways of exposure and health significance of these findings need to be further investigated.",
Arsenic,1030696,"The life and work of Abu ul-Ala Shirazi (d. 1001): a Persian pioneer in the treatment of malaria, in the style of Rhazes (865-925) Abstract: Abu ul-Ala Shirazi, who lived around the 10th century at the Court of Amir Azud ul-Duleh Bueieh (902-951) from the Dailami Dynasty, found that arsenic, known as sam-al-far, could cure malaria. A clinical trial dating from the 10th century demonstrates Abu ul-Ala's intelligence and careful clinical observation, in the tradition of Rhazes' practice based on experimentation and clinical trial.",
Arsenic,1031449,"Ecological and human health risk aspects of burning arsenic-rich coal Abstract: The subject of the study was the ecological and human health consequences of environmental pollution from emissions arising from burning local coal with an arsenic content ranging from 900 to 1,500 g/tonne of dry substance. The first indication of environmental pollution by arsenic-containing emissions was the mass extinction of honeybee colonies. The neurotoxic and carcinogenic aspects of arsenic exposure were followed. On using a group diagnostics approach, significant hearing losses were detected in exposed children in both air and bone conduction audiometry at high frequency range (4,000 and 8,000 Hz, respectively). Exposure assessment of the local population of the Prievidza district, Central Slovakia, was based on biological monitoring. The criterion of higher exposure was arsenic content in hair exceeding concentrations of 3 microg/g of hair. In a 7.5-km radius of the exposed region, live about two-tenths of the district population who were considered as &quot;exposed&quot; and rest of the district served as the &quot;reference&quot; population. The subject of our analysis was a database of 1,503 non-melanoma skin cancer (NMSC) cases (756 in men and 747 in women) collected from 1977 to 1996 in the Prievidza district, Central Slovakia (population approximately 125,000). The age standardized incidence of NMSC (each confirmed by histological examination) in non-occupational settings ranged from 45.9 to 93.9 in men and from 34.6 to 81.4 in women. Analysis of our data demonstrates a positive correlation between human cumulative exposure to arsenic and incidence of NMSC.",
Arsenic,1018345,"Arsenite retards DNA break rejoining by inhibiting DNA ligation Abstract: Arsenic has been shown to inhibit methyl methane-sulphonate (MMS)-induced DNA repair but the exact mechanism remains controversial. The purpose of this investigation is to examine which step of DNA repair is most sensitive to arsenite (As) and how As inhibits it. The results from single-cell alkaline electrophoresis, showing post-treatment with As increased DNA strand breaks in MMS-treated cells, suggest that that the excision step seems to be less sensitive to As than later steps. To test this hypothesis, hydroxyurea (Hu) plus cytosine-beta-D-arabinofuranoside (AraC) were used to block DNA polymerization, allowing the DNA strand breaks to accumulate. These experiments indicated that As had weak inhibitory effects on DNA strand break accumulation. However, As inhibited the rejoining of those DNA strand breaks which could be rejoined within 4 h after release from blockage by Hu plus AraC. To further elucidate this mechanism, a cell extract was used to compare the relative sensitivity of the various steps in DNA repair to As. The potency of the As inhibitory effect as deduced from concentration-response curves were: ligation of poly(rA).oligo(dT) &gt; ligation of poly(dA).oligo(dT) approximately DNA polymerization &gt; or = DNA repair synthesis &gt; excision. As is known to inhibit the activity of pyruvate dehydrogenase by interacting with vicinal dithiol groups. Dithiothreitol could effectively remove As inhibition of both the ligation of poly(rA).oligo(dT) and the activity of pyruvate dehydrogenase but had no obvious effect on As inhibition of poly(dA).oligo(dT) ligation. Since DNA ligase III contains vicinal dithiol groups, we postulate that As may inhibit DNA break rejoining by interacting with the vicinal dithiols to inactivate DNA ligation in MMS-treated cells.",
Arsenic,1033314,"Pyruvate metabolism after in vivo exposure to oral arsenic Abstract: This study investigated altered pyruvate metabolism after prolonged oral arsenic exposure. Male rats were given access to deionized drinking water containing 0, 40 or 85 ppm sodium arsenate (As5+) for 3 weeks. Respiration studies with mitochondria isolated from treated animals indicated decreased state 3 respiration (with ADP) and decreased respiratory control ratios (RCR) for pyruvate/malate-mediated respiration, but not for succinate-mediated respiration, as compared to control respiration values. In addition, pyruvate dehydrogenase activity was measured, in both liver and intestine, before and after Mg-activation in vitro. After 3 weeks, the effects of arsenic at the highest dose level were pronounced on the basal pyruvate dehydrogenase activity (before activation) as well as the total pyruvate dehydrogenase (after activation). The inhibition of pyruvate dehydrogenase activity both before and after Mg-activation suggests an arsenic effect on mitochondrial pyruvate metabolism which, in part, involves inhibition of pyruvate decarboxylase. Evidence is also presented which may indicate an arsenic effect on the kinase and/or phosphatase which regulate pyruvate dehydrogenase activity.",
Arsenic,1033444,"Lung cancer among women residing close to an arsenic emitting copper smelter Abstract: Lung cancer deaths occurring between 1935 and 1969 among women residing near an arsenic emitting smelter were examined. For three geographically defined exposure groups, the observed and expected number of lung cancer deaths were compared. In none of the exposure groups did the observed number of deaths exceed the expected. However, an index of exposure based on distance of residence from the smelter and duration of residence in the area was 27% higher for cases than for age-matched controls (p = .10). Adjusting for a latency of 20 yr, case exposures were 23% higher than for controls (p = .07). Dividing individuals into quintiles of exposure yielded odds ratios ranging from 1 to 1.6 (test of trend, p = .07).",
Arsenic,1508653,"Position-specific isotope analysis of the methyl group carbon in methylcobalamin for the investigation of biomethylation processes Abstract: In the environment, the methylation of metal(loid)s is a widespread phenomenon, which enhances both biomobility as well as mostly the toxicity of the precursory metal(loid)s. Different reaction mechanisms have been proposed for arsenic, but not really proven yet. Here, carbon isotope analysis can foster our understanding of these processes, as the extent of the isotopic fractionation allows to differentiate between different types of reaction, such as concerted (S(N)2) or stepwise nucleophilic substitution (S(N)1) as well as to determine the origin of the methyl group. However, for the determination of the kinetic isotope effect the initial isotopic value of the transferred methyl group has to be determined. To that end, we used hydroiodic acid for abstraction of the methyl group from methylcobalamin (CH(3)Cob) or S-adenosyl methionine (SAM) and subsequent analysis of the formed methyl iodide by gas chromatography (GC) isotope ratio mass spectrometry (IRMS). In addition, three further independent methods have been investigated to determine the position-specific ? (13)C value of CH(3)Cob involving photolytic cleavage with different additives or thermolytic cleavage of the methyl-cobalt bonding and subsequent measurement of the formed methane by GC-IRMS. The thermolytic cleavage gave comparable results as the abstraction using HI. In contrast, photolysis led to an isotopic fractionation of about 7 to 9 ‰. Furthermore, we extended a recently developed method for the determination of carbon isotope ratios of organometal(loid)s in complex matrices using hydride generation for volatilization and matrix separation before heart-cut GC and IRMS to the analysis of the low boiling partly methylated arsenicals, which are formed in the course of arsenic methylation. Finally, we demonstrated the applicability of this methodology by investigation of carbon fractionation due to the methyl transfer from CH(3)Cob to arsenic induced by glutathione.",
Arsenic,1344451,Chromosome alterations and hyperproliferation associated with chronic arsenic exposure Abstract: ,
Arsenic,1508708,Discrete distribution of implanted and annealed arsenic atoms in silicon nanowires and its effect on device performance Abstract: We have theoretically investigated the effects of random discrete distribution of implanted and annealed arsenic (As) atoms on device characteristics of silicon nanowire (Si NW) transistors. Kinetic Monte Carlo simulation is used for generating realistic random distribution of active As atoms in Si NWs. The active As distributions obtained through the kinetic Monte Carlo simulation are introduced into the source and drain extensions of n-type gate-all-around NW transistors. The current-voltage characteristics are calculated using the non-equilibrium Green's function method. The calculated results show significant fluctuation of the drain current. We examine the correlation between the drain current fluctuation and the factors related to random As distributions. We found that the fluctuation of the number of dopants in the source and drain extensions has little effect on the on-current fluctuation. We also found that the on-current fluctuation mainly originated from the randomness of interatomic distances of As atoms and hence is inherent in ultra-small NW transistors.,
Arsenic,1353720,"Classification of Geographical Origin by PNN Analysis of Fatty Acid Data and Level of Contaminants in Oils From Peruvian Anchovy Abstract: The aim of this study was to examine Peruvian anchovy oil fatty acid (FA) compositions, and to test the possibility of using the FA data to classify the oils according to geographical origin along the Peruvian coast. The levels of contaminants in a representative set of samples were determined to examine the general levels and investigate if such measurements could aid in future discrimination between oils. The FA results showed that the two known stocks of Peruvian anchovy displayed different levels of docosahexaenoic acid (DHA, 22:6n-3) (southern stock; 14.4 +/- A 0.8% versus central-northern stock; 9.9 +/- A 1.2%). However, principal component analysis (PCA) of the FA data indicated clusters according to three regions; North, Center and South. Using a data set of 57 anchovy samples and 21 FA as input, a probabilistic neural network (PNN) was constructed. For the validation data sets, ""North"" oils was predicted accurately 100% of the time, ""Center"" oils 100% and ""South"" oils 83% of the time. The levels of contaminants in the oils determined were low in all but one sample.",
Arsenic,1597452,Bacteria-Modified Red Mud for Adsorption of Cadmium Ions from Aqueous Solutions Abstract: ,
Arsenic,900900,"Effects of exogenous methionine on arsenic burden and NO metabolism in brain of mice exposed to arsenite through drinking water Abstract: The aim of this study was to explore the effects of exogenous methionine (Met) on arsenic burden and metabolism of nitric oxide (NO) in the brain of mice exposed to arsenite via drinking water. Mice were exposed to sodium arsenite through drinking water contaminated with 50 mg/L arsenic for four consecutive weeks, and treated intraperitoneally with saline solution, 100 mg/kg body weight (b.w), 200 mg/kg b.w or 400 mg/kg b.w of Met, respectively at the fourth week. Levels of inorganic arsenic (iAs), monomethylarsenic acid (MMAs), and dimethylarsenic acid (DMAs) in the liver, blood and brain were determined by method of hydride generation coupled with atomic absorption spectrophotometry. Nitric oxide synthase (NOS) activities and NO levels in the brain were determined by colorimetric method. Compared with mice exposed to arsenite alone, administration of Met increased significantly the primary methylation ratio in the liver, which resulted in decrease of percent iAs and increase of percent DMAs in the liver, and decrease of iAs, MMAs and total arsenic levels (TAs) in the blood and DMAs and TAs in the brain. NOS activities and NO levels in the brain of mice exposed to arsenite alone were significantly lower than those in control, however administration of Met could increase significantly NO levels. Findings from this study suggested that exogenous Met could benefit the primary arsenic methylation in the liver, which might increase the production of methylated arsenicals and facilitate arsenic excretion. As a consequence, arsenic burden in both blood and brain was reduced, and toxic effects on NO metabolism in the brain were ameliorated. © 2011 Wiley Periodicals, Inc. Environ Toxicol 2011.",
Arsenic,1339033,"Synergistic effect of conjugated linolenic acid isomers against induced oxidative stress, inflammation and erythrocyte membrane disintegrity in rat model Abstract: <strong>BACKGROUND: </strong>?-Eleostearic acid and punicic acid, two typical conjugated linolenic acid (CLnA) isomers present in bitter gourd and snake gourd oil respectively, exhibit contrasting cis-trans configuration which made them biologically important.<br /><br /><strong>METHODS: </strong>Rats were divided into six groups. Group 1 was control and group 2 was treated control. Rats in the groups 3 and 4 were treated with mixture of ?-eleostearic acid and punicic acid (1:1) (0.5% and 1.0% respectively) while rats in the groups 5 and 6 were treated with 0.5% of ?-eleostearic acid and 0.5% of punicic acid respectively along with sodium arsenite by oral gavage once per day.<br /><br /><strong>RESULTS: </strong>Results showed that increase in nitric oxide synthase (NOS) activity, inflammatory markers expression, platelet aggregation, lipid peroxidation, protein oxidation, DNA damage and altered expression of liver X receptor-? (LXR-?) after arsenite treatment were restored with the supplementation of oils containing CLnA isomers. Altered activities of different antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and ferric reducing ability of plasma (FRAP) also restored after oil supplementation. Altered morphology and fluidity of erythrocyte membrane studied by atomic force and scanning electron microscopy, after stress induction were significantly improved due to amelioration in cholesterol/phospholipid ratio and fatty acid profile of membrane. Oils treatment also improved morphology of liver and fatty acid composition of hepatic lipid.<br /><br /><strong>CONCLUSIONS: </strong>Overall two isomers showed synergistic antioxidant and anti-inflammatory effect against induced perturbations and membrane disintegrity.<br /><br /><strong>GENERAL SIGNIFICANCE: </strong>Synergistic antioxidant and anti-inflammatory role of these CLnA isomers were established by this study.",1
Arsenic,1033003,An inquest on the death of Charles Francis Hall Abstract: ,
Arsenic,627962,"Lymphocyte proliferation kinetics and genotoxic findings in a pilot study on individuals chronically exposed to arsenic in Mexico Abstract: In the search for early biological markers to detect genetic damage, a pilot study on a hydroarsenicism-exposed group was designed. Blood and urine samples were taken from 11 individuals chronically exposed and from 13 individuals with lower exposure to the metal. Lymphocyte cultures for cytogenetic studies and HGPRT assay were done with coded peripheral blood samples, while arsenic levels and the “rec assay” in B. subtilis were determined in urine samples. The highly exposed group excreted greater amounts of As, nevertheless the rec assay showed negative results. An interesting finding is that the cell-cycle kinetics exhibited a significant difference between the groups studied, the average generation time (AGT) was longer in the highly exposed group. The percentages of chromosomal aberrations and the frequencies of sister-chromatid exchanges were similar in both populations, although complex aberrations were more frequent in the highly exposed group, which also showed a higher average variation frequency in the HGPRT assay, but the 2 latter observations were not statistically significant. The lag in lymphocyte proliferation could mean an impairment of the immune response due to arsenic exposure.",
Arsenic,2345830,"Arsenic fixation and mobilization in the soils of the Ganges and Meghna floodplains. Impact of pedoenvironmental properties Abstract: Arsenic contamination of groundwaters in the floodplain of the Ganges-Meghna river system can represent a serious threat to human health and to the sustainability of irrigated rice cultivation. The extent of As accumulation in the soils irrigated with As-containing groundwater seems to vary among different study areas and the relationships between the pedoenvironmental conditions and As fixation/mobilization are not yet completely elucidated. This work was aimed to assess how soil and environmental properties interact in affecting the fixation/mobilization of As in the soils of the Ganges and Meghna agricultural zones. For this purpose, soil samples from different districts in the Ganges and Meghna floodplains have been characterized, different pools of As, Fe, Mn and P have been quantified and the results have been related to the main soil and environmental characteristics of the two areas. The As content in groundwater and the baseline As concentration in the parent material in the two zones would point to a higher As accumulation in the Meghna floodplain soils, however the Ganges floodplain soils had higher contents of As in all fractions, proving the key role of the factors controlling the release/fixation of As. The soils of the two floodplains, in fact, differed for most physicochemical properties. The ones from the Ganges floodplain were calcareous, with finer texture and generally richer in Fe but oxalate extractable Fe was higher in the Meghna floodplain soils, suggesting a higher degree of waterlogging. This is in agreement with the averagely longer duration and higher depth of submersion of the soils of this area, which enhanced Fe dynamics and favored the release of the less tightly bonded As forms. The competing effect of P was probably similar in the two areas, since P concentrations did not differ significantly among the two soil series. However, more P was Olsen extractable in the Meghna floodplain soils, in contrast with As, that was more easily extracted from the Ganges floodplain soils. The concentration and potential mobility of the retained As were hence greater in the soils of the Ganges floodplain. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,1240141,"Arsenic exposure through groundwater in the middle Ganga plain in the Varanasi environs, India: A future threat Abstract: The study area covers an about 100 km2 of the middle Ganga plain in Uttar Pradesh, experiencing intensive groundwater extraction. In order to recognize the arsenic contamination zones of the Varanasi environs, sixty eight groundwater samples have been collected and analyzed for major ions, iron and arsenic. Twenty one sediment samples in the four boreholes were also collected to deduce the source of arsenic in the groundwater. The preliminary survey reports for the first time indicates that part of rural and urban population of Varanasi environs are drinking and using for irrigation arsenic contaminated water mostly from hand tube wells (<70 m). The study area is a part of middle Ganga plain which comprises of Quaternary alluvium consists of an alternating succession of clay, clayey silt and sand deposits. The high arsenic content in groundwater samples of the study area indicates that 14% of the samples are exceeding the 10 ?g/l and 5% of the samples are exceeding 50 ?g/l. The high arsenic concentration is found in the villages such as Bahadurpur, Madhiya, Bhojpur, Ratanpur, Semra, Jalilpur, Kateswar, Bhakhara and Kodupur (eastern side of Ganga River in Varanasi), situated within the newer alluvium deposited during middle Holocene to Recent. The older alluvial aquifers situated in the western side of the Ganga River are arsenic safe (maximum As concentration of 9 ?g/l) though the borehole sediments shows high arsenic (mean 5.2 mg/kg) and iron content (529 mg/kg) in shallow and medium depths. This may be due to lack of reducing conditions (i.e organic content) for releasing arsenic into the groundwater. Rainfall infiltration, organic matter from recently accumulated biomass from flood prone belt in the newer alluvium plays a critical role in releasing arsenic and iron present in sediments. The main mechanism for the release of As into groundwater in the Holocene sandy aquifer sediments of Varanasi environs may be due to the reductive dissolution of Fe oxyhydroxide present as coatings on sand grains as well as altered mica content. The high societal problems of this study will help to mitigate the severity of arsenic contamination by providing alternate drinking water resources to the people in middle Ganga plain and to arrange permanent arsenic safe drinking water source by the authorities.",
Arsenic,1024524,"Reactive oxygen species-dependent HSP90 protein cleavage participates in arsenical As(+3)- and MMA(+3)-induced apoptosis through inhibition of telomerase activity via JNK activation Abstract: The effects of six arsenic compounds including As(+3), MMA(+3), DMA(+3), As(+5), MMA(+5), and DMA(+5) on the viability of NIH3T3 cells were examined. As(+3) and MMA(+3), but not the others, exhibited significant cytotoxic effects in NIH3T3 cells through apoptosis induction. The apoptotic events such as DNA fragmentation and chromosome condensation induced by As(+3) and MMA(+3) were prevented by the addition of NAC and CAT, and induction of HO-1 gene expression in accordance with cleavage of the HSP90 protein, and suppression of telomerase activity were observed in NIH3T3 cells under As(+3) and MMA(+3) treatments. An increase in the intracellular peroxide level was examined in As(+3)- and MMA(+3)-treated NIH3T3 cells, and As(+3)- and MMA(+3)-induced apoptotic events were blocked by NAC, CAT, and DPI addition. HSP90 inhibitors, GA and RD, significantly attenuated the telomerase activity in NIH3T3 cells with an enhancement of As(+3)- and MMA(+3)-induced cytotoxicity. Suppression of JNKs significantly inhibited As(+3)- and MMA(+3)-induced apoptosis by blocking HSP90 protein cleavage and telomerase reduction in NIH3T3 cells. Furthermore, Hb, SnPP, and dexferosamine showed no effect against As(+3)- and MMA(+3)-induced apoptosis, and overexpression of HO-1 protein or inhibition of HO-1 protein expression did not affect the apoptosis induced by As(+3) or MMA(+3). These data provide the first evidence to indicate that apoptosis induced by As(+3) and MMA(+3) is mediated by an ROS-dependent degradation of HSP90 protein and reduction of telomerase via JNK activation, and HO-1 induction might not be involved.",
Arsenic,80331,"Toenail trace element levels and breast cancer: A prospective study Abstract: The associations between toenail levels of five trace elements and breast cancer risk were studied among a cohort of 62, 641 US women who provided toenail clippings and were free from diagnosed breast cancer in 1982. Among 433 cases of breast cancer identified during 4 years of follow-up and their matched controls, the odds ratios comparing the highest with the lowest quintiles and adjusted for established breast cancer risk factors were as follows: for arsenic, 1.12 (95% confidence interval (CI) 0.66-1.91); for copper, 0.91 (95% CI 0.59-1.42); for chromium, 0.96 (95% Cl 0.61-1.52); for iron, 0.89 (95% CI 0.56-1.40); and for zinc, 1.09 (95% CI 0.70-1.70). Among postmenopausal women, a marginally significant positive association was observed between toenail chromium levels and breast cancer risk (odds ratio = 1.71, 95% Cl 0.87-3.35) (p for trend = 0.07). However, the association between chromium and breast cancer risk was inverse among premenopausal women. Although data on the validity of toenail levels of certain of these elements are limited, these results do not provide evidence for an important effect of arsenic, copper, chromium, iron, or zinc on breast cancer risk.",
Arsenic,2064259,"Effects of arsenate, chromate, and sulfate on arsenic and chromium uptake and translocation by arsenic hyperaccumulator Pteris vittata L Abstract: We investigated effects of arsenate (AsV), chromate (CrVI) and sulfate on As and Cr uptake and translocation by arsenic hyperaccumulator Pteris vittata (PV), which was exposed to AsV, CrVI and sulfate at 0, 0.05, 0.25 or 1.25 mM for 2-wk in hydroponic system. PV was effective in accumulating large amounts of As (4598 and 1160 mg/kg in the fronds and roots at 0.05 mM AsV) and Cr (234 and 12,630 mg/kg in the fronds and roots at 0.05 mM CrVI). However, when co-present, AsV and CrVI acted as inhibitors, negatively impacting their accumulation in PV. Arsenic accumulation in the fronds was reduced by 92% and Cr by 26%, indicating reduced As and Cr translocation. However, addition of sulfate increased uptake and translocation of As by 26-28% and Cr by 1.63 fold. This experiment demonstrated that As and Cr inhibited each other in uptake and translocation by PV but sulfate enhanced As and Cr uptake and translocation by PV.",
Arsenic,1453819,"Arsenic Trioxide Toxicity in H9c2 Myoblasts-Damage to Cell Organelles and Possible Amelioration with Boerhavia diffusa Abstract: Arsenic trioxide (ATO) has been long used as a chemotherapeutic agent because of its significant anticancer property. Unfortunately, the use of ATO is limited due to its cardiotoxic effects. The present study evaluates the protective property of ethanolic extract of Boerhavia diffusa (BDE) against ATO-induced toxicity on various cell organelles in H9c2 cardiomyocytes. The effects of different concentrations of ATO (5, 7.5 and 10 ?M) on cell organelles like mitochondria, endoplasmic reticulum (ER), lysosome and actin, generation of reactive oxygen species, antioxidant enzyme status and intracellular calcium overload were evaluated. ATO significantly (P ? 0.05) altered mitochondrial transmembrane potential, intracellular calcium level, ER, lysosomal activity and F-actin network in addition to induction of oxidative stress. Co-treatment with BDE protected the cardiomyocytes from the adverse effects of ATO, especially at 5 ?M concentration, which was evident from decreased activity of lactate dehydrogenase (5 ?M ATO + 20 ?g/mL BDE: 6.61 ± 1.97 ?U/mL, respective control group: 16.15 ± 1.92 ?U/mL), reduced oxidative stress, calcium influx and organelle damage. Results obtained from the present study allow for a better characterization of the effects of ATO on H9c2 myoblasts. In conclusion, our data suggest that cell organelles are also the targets of ATO-induced cardiotoxicity in addition to other reported targets like ion channels, and BDE has the potential to protect the cardiotoxicity induced by ATO.",
Arsenic,1597294,"Concentrations of arsenic, cadmium and lead in selected foodstuffs from Serbian market basket: Estimated intake by the population from the Serbia Abstract: In this study arsenic (As), cadmium (Cd) and lead (Pb) were determined in 114 samples of various food items collected at supermarkets located in Novi Sad, the capitol of the northern Serbian province of Vojvodina in January 2012 and March 2013. The considered items represented the most consumed foodstuffs according to the &quot;national market basket&quot;. The highest concentrations were obtained for Pb in candy (0.323 mg kg-1), for Cd in paprika (0.118 mg kg(-1)) and for As in canned fish (0.43 mg kg(-1)). The results were compared with the relevant data on the occurrence of these toxic elements available in literature for other European countries. Human health risk assessment through dietary exposure was evaluated for Serbian adult consumers. The estimated intakes were compared with available toxicological references to assess the risk of As, Cd and Pb intake through consumption of analyzed food items. The highest intake were estimated for Pb being 72.30 ?g day-1 for adult population, while intakes of As and Cd were significantly lower (21.89 ?g day-1 and 11.51 ?g day-1, respectively).",
Arsenic,1020208,"Apoptosis and necrosis in developing brain cells due to arsenic toxicity and protection with antioxidants Abstract: Epidemiological studies on arsenic contamination in drinking water indicated presence of arsenic in fetal tissues. Experiments on human fetal brain explants on exposure to arsenic in culture showed disturbance in lipid peroxidation, generation of nitric oxide (NO), reactive oxygen species (ROS) and apoptosis. The oxidative stress challenged by antioxidant vitamins C, E or chelator dimercaptosuccinic acid (DMSA) may reverse arsenic toxicity on neuronal development. The concept was tested with the models: (A) human fetal brain explants exposed to arsenic, 0.3 mg/l in culture for 24 h; (B) rat neonatal brain explants from 1-day-old litters exposed to 0.3 mg/l arsenic in drinking water during gestation. Rats (n=10) were given oral administration of vitamin C, 2.5 mg/kg/day, vitamin E, 148 microg/kg/day during gestation and DMSA, 50 mg/kg for 2 days at the end of gestation. (A) The arsenic induced in human fetal brain explants increase in production of NO, 20% and ROS, 25%, and decrease in DNA, 62% and protein, 54% synthesis. The morphological analyses showed growth of viable cells, neural networking vis-à-vis apoptosis on exposure to arsenic for 24 h and necrosis and loss of ground matrix on arsenic exposure for 18 days. The occurrence of two processes of apoptosis and necrosis in different neurons of same culture indicated existence of a selective cellular defense against arsenic toxicity. (B) The rats exposed to arsenic showed increased generation of NO, 25% and ROS, 22%, loss of glutathione content from 42 to 35 microg/mg protein, 40% increase in lipid peroxidation and decreased superoxide dismutase at 32%. The administration of vitamins C, E and DMSA showed partial reversal of the effects indicating possible protection from arsenic toxicity.",
Arsenic,1019949,"Caspase activation is accelerated by the inhibition of arsenite-induced, membrane rafts-dependent Akt activation Abstract: Renewed interest in arsenic has been shown recently due to its dual nature of being a potent toxin and a drug for treatment of acute promyelocytic leukemia (APL) because of its ability to trigger caspase activation. Here, we found that sodium arsenite (NaAsO(2)) also triggers the signal for activation of Akt and downstream glycogen synthase 3beta (GSK3beta). Such Akt/GSK3beta activation was abrogated completely by wortmannin, an inhibitor of PI-3 kinase, and greatly by pertussis toxin, a G-protein inhibitor. Arsenite-induced Akt phosphorylation also was inhibited by sequestrating membrane cholesterol with beta cyclodextrin. Reducing reagents/reactive oxygen species (ROS) scavengers reduced arsenite-induced Akt phosphorylation and beta cyclodextrin reduced arsenite-mediated ROS production, suggesting that arsenite-induced G-protein/Akt/GSK3beta pathway is membrane raft dependent and redox linked. We also found that a combination of a low concentration (1 microM) of arsenite and wortmannin triggers the signal for caspase activation, whereas neither of these elements alone did so. These results suggested that selective blockade of the arsenite-provoked PI-3 kinase/Akt pathway can promote the arsenite-triggered pathway for caspase activation, and this may open a new study area for wider applications of arsenic as a drug for treating various kinds of leukemia.",
Arsenic,1070314,"Chemical and sewage sludge co-incineration in a full-scale MSW incinerator: Toxic trace element mass balance Abstract: Co-incineration of sludges with MSW is a quite common practice in Europe. This paper illustrates a case of co-incineration of both sewage sludges and chemical sludges, the latter obtained from drinking water production, in a waste-to-energy (WTE) plant located in northern Italy and equipped with a grate furnace, and compares the toxic trace elements mass balance with and without the co-incineration of sludges. The results show that co-incineration of sewage and chemical sludges does not result in an increase of toxic trace elements the total release in environment, with the exception of arsenic, whose total release increases from 1 mg t(fuel)(-1) during standard operation to 3 mg t(fuel)(-1) when sludges are co-incinerated. The increase of arsenic release is, however, attributable to the sole bottom ashes, where its concentration is five times higher during sludge co-incineration. No variation is observed for arsenic release at the stack. This fact is a further guarantee that the co-incineration of sludges, when performed in a state-of-the-art WTE plant, does not have negative effects on the atmospheric environment.",
Arsenic,735031,"Oxidative metabolism of lung macrophages exposed to sodium arsenite Abstract: Arsenic pollution has become increasingly severe. It occurs as the result of geological processes and different human activities. Arsenic toxicity at the respiratory level occurs mainly by inhalation of products of coal combustion. The aim of this study was to evaluate sodium arsenite (As(3+)) toxicity in murine alveolar macrophages (AMs) in vitro and its association with the alterations in cell metabolism. No changes in viability, apoptosis or cell area were detected in AMs treated with As(3+) concentrations up to 2 microM for 24-96 h. A marked decrease in these end-points was observed for As(3+) concentrations ranging from 2.5 microM to 10 microM. Regarding the dynamics of the endo-exocytic process triggered by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell incorporation, no variations were detected for As(3+) concentrations lower than 2 microM while higher concentrations markedly modified this response. MTT specific activity, as a measure of cell metabolic activity, was not modified irrespective of the As(3+) concentration assayed. However, nitroblue tetrazolium (NBT) specific activity, as a measure of superoxide anion generation, is responsive but only to low As(3+) doses. Although this study focuses on lung macrophages, the effects of As(3+) described herein may also apply to the response of macrophages residing in other organs. Arsenite modifies the metabolic and the oxidative status of AMs in vitro. When macrophages are in an As(3+) rich medium, they exhibit a reduction in respiratory burst levels and lose their intrinsic capacity to respond to toxicants.",
Arsenic,1355243,Sodium arsenite and heat shock induce stress proteins in precision-cut rat liver slices Abstract: The use of stress proteins as indicators of early liver damage was studied. Protein expression was examined in liver slices prepared from Sprague-Dawley-rats incubated in a sodium-arsenite (7784465) containing solution or exposed to heat shock. Early cytotoxicity as evidenced by intracellular potassium leakage was identified in arsenite exposed liver slices. Arsenite did not affect protein synthesis which was found to occur in a linear manner up to 24 hours during incubation; the number of proteins synthesized was decreased by heat shock. Both heat shock and arsenite were found to induce the production of the heat shock protein (HSP) 70 family of proteins as well as HSP 90. HSP 70 proteins were induced to a much greater extent than HSP 90. Induction of stress proteins was seen in response to concentrations of arsenite which did not induce leakage of intracellular potassium or influence total protein synthesis. The authors conclude that the induction of stress proteins appears to be useful as an indicator of early arsenite induced hepatic injury.,
Arsenic,1342660,Studies on Environmental Effects of Underwater Chemical Munitions in the Southern Adriatic Sea (Mediterranean Sea) Abstract: ,
Arsenic,2345813,"Assessment of Ethidium bromide and Ethidium monoazide bromide removal from aqueous matrices by adsorption on cupric oxide nanoparticles Abstract: The present study was undertaken to develop an effective adsorbent and to study the adsorption of Ethidium bromide and Ethidium monoazide bromide from aqueous solution using the CuO nanopartides. The characteristics of CuO nanoparticles were determined and found to have a surface area 89.59 m(2)/g. Operational parameters such as pH, contact time and adsorbent concentration, initial concentration and temperature were also studied. The amount of removal increases with the increase in pH from one to seven and reaches the maximum when the pH is nine. Adsorption data fitted well with the Langmuir, Freundlich and Florry-Huggins models. The results show that the best fit was achieved with the Langmuir isotherm equation with maximum adsorption capacities of 0.868 and 0.662 mg/g for Ethidium bromide and Ethidium monoazide bromide, respectively. The adsorption process was found to follow pseudo-second-order kinetics. The calculated thermodynamic parameters, namely Delta G, Delta H and AS showed that adsorption of Ethidium bromide and Ethidium monoazide bromide was spontaneous and endothermic under examined conditions. (C) 2013 Elsevier Inc. All rights reserved.",
Arsenic,1797776,"Trace elements and endometriosis: The ENDO study Abstract: There has been limited study of trace elements and endometriosis. Using a matched cohort design, 473 women aged 18-44 years were recruited into an operative cohort, along with 131 similarly-aged women recruited into a population cohort. Endometriosis was defined as surgically visualized disease in the operative cohort, and magnetic resonance imaging diagnosed disease in the population cohort. Twenty trace elements in urine and three in blood were quantified using inductively coupled plasma mass spectrometry. Logistic regression estimated the adjusted odds (aOR) of endometriosis diagnosis for each element by cohort. No association was observed between any element and endometriosis in the population cohort. In the operative cohort, blood cadmium was associated with a reduced odds of diagnosis (aOR=0.55; 95% CI: 0.31, 0.98), while urinary chromium and copper reflected an increased odds (aOR=1.97; 95% CI: 1.21, 3.19; aOR=2.66; 95% CI: 1.26, 5.64, respectively). The varied associations underscore the need for continued research.",
Arsenic,2064267,"Association between exposure to low to moderate arsenic levels and incident cardiovascular disease: A prospective cohort study Abstract: <strong>BACKGROUND: </strong>Long-term exposure to high levels of arsenic is associated with increased risk for cardiovascular disease, whereas risk from long-term exposure to low to moderate arsenic levels (&lt;100 µg/L in drinking water) is unclear.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the association between long-term exposure to low to moderate arsenic levels and incident cardiovascular disease.<br /><br /><strong>DESIGN: </strong>Prospective cohort study.<br /><br /><strong>SETTING: </strong>The Strong Heart Study baseline visit between 1989 and 1991, with follow-up through 2008.<br /><br /><strong>PATIENTS: </strong>3575 American Indian men and women aged 45 to 74 years living in Arizona, Oklahoma, and North and South Dakota.<br /><br /><strong>MEASUREMENTS: </strong>The sum of inorganic and methylated arsenic species in urine at baseline was used as a biomarker of long-term arsenic exposure. Outcomes were incident fatal and nonfatal cardiovascular disease.<br /><br /><strong>RESULTS: </strong>A total of 1184 participants developed fatal and nonfatal cardiovascular disease. When the highest- and lowest-quartile arsenic concentrations (&gt;15.7 vs. &lt;5.8 µg/g creatinine) were compared, the hazard ratios for cardiovascular disease, coronary heart disease, and stroke mortality after adjustment for sociodemographic factors, smoking, body mass index, and lipid levels were 1.65 (95% CI, 1.20 to 2.27; P for trend &lt; 0.001), 1.71 (CI, 1.19 to 2.44; P for trend &lt; 0.001), and 3.03 (CI, 1.08 to 8.50; P for trend = 0.061), respectively. The corresponding hazard ratios for incident cardiovascular disease, coronary heart disease, and stroke were 1.32 (CI, 1.09 to 1.59; P for trend = 0.002), 1.30 (CI, 1.04 to 1.62; P for trend = 0.006), and 1.47 (CI, 0.97 to 2.21; P for trend = 0.032), respectively. These associations varied by study region and were attenuated after further adjustment for diabetes, hypertension, and kidney disease measures.<br /><br /><strong>LIMITATIONS: </strong>Direct measurement of individual arsenic levels in drinking water was unavailable.<br /><br /><strong>CONCLUSION: </strong>Long-term exposure to low to moderate arsenic levels was associated with cardiovascular disease incidence and mortality.<br /><br /><strong>PRIMARY FUNDING SOURCE: </strong>National Heart, Lung, and Blood Institute and National Institute of Environmental Health Sciences.",
Arsenic,1019417,"Arsenite uptake and metabolism by rat hepatocyte primary cultures in comparison with kidney- and hepatocyte-derived rat cell lines Abstract: Biotransformation by methylation to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) influences inorganic arsenical toxicity, which is often investigated in cultured cells. Arsenic (III) uptake and methylation was assessed in rat hepatocytes in primary culture and in three established rat cell lines (hepatoma-derived McA-RH 7777 cells and H4-II-EC-3 cells, and kidney epithelium-derived NRK-52E cells) to compare their use as model systems for arsenite metabolism. Incubation of all cell types with 0.27, 0.67, 1.33, 2.67, or 6.67 microM As(III) concentrations resulted in concentration-dependent arsenic uptake and biomethylation. Arsenic uptake by the NRK-52E cells was initially slower than that of the other cells, but by 8 h, total uptake was similar in all cell types. At the lowest arsenite concentration, the percentages of total arsenic methylated to MMA and DMA by the hepatocytes and the McA-RH 7777 cells were similar (67 and 66%); methylation by the H4-II-EC-3 cells was somewhat lower (52%), and methylation by the kidney-derived NRK-52E cells was much lower (15%). Total arsenic methylation was inhibited in the cell lines, but not in the hepatocytes, at the highest arsenite concentrations. In all cases, exposure to increased arsenite concentrations inhibited conversion of MMA to DMA much more than it affected the initial methylation step (inorganic arsenite to MMA). These results indicate that rat hepatocytes in primary culture and established rat hepatoma-derived cell lines are similar in their abilities to accumulate and methylate arsenic to MMA and DMA at environmentally relevant arsenic concentrations in the medium. They differed from the kidney epithelium-derived cells, which exhibited substantially lower biomethylation activity.",
Arsenic,2088352,A simple fluorescent assay for lead(II) detection based on lead(II)-stabilized G-quadruplex formation Abstract: ,
Arsenic,627625,"Oxidative DNA adducts and DNA-protein cross-links are the major DNA lesions induced by arsenite Abstract: Arsenic is recognized to be a nonmutagenic carcinogen because it induces DNA damage only at very high concentrations. However, many more DNA strand breaks could be detected by digesting the DNA of arsenite-treated cells with endonuclease III, formamidopyrimidine-DNA glycosylase, and proteinase K. By doing so, arsenite could be shown to induce DNA damage in human cells within a pathologically meaningful concentration range. Oxidized guanine products were detected in all arsenite-treated human cells examined. DNA-protein cross-links were also detected in arsenite-treated NB4 and HL60 cells. In human umbilical vein endothelial cells, the induction of oxidized guanine products by arsenite was sensitive to inhibitors of nitric oxide (NO) synthase but not to oxidant modulators, whereas the opposite result was obtained in vascular smooth muscle cells. On the other hand, the arsenite-induced oxidized guanine products and DNA-protein cross-links in NB4 and HL60 cells were sensitive to modulators of calcium, NO synthase, oxidant, and myeloperoxidase. Therefore, although oxidized guanine products were detected in all the human cells treated with arsenite, the pathways could be different in different cell types. Because the sensitivity and the mechanism of arsenic intoxication are cell specific, it is important that target tissues and target cells are used for investigations. It is also important that pathologically or pharmacologically meaningful concentrations of arsenic are used. This is because in most cases we are dealing with the chronic effect rather than acute toxicity.",
Arsenic,1029331,"Reduction and methylation of sodium arsenate in the rat Abstract: After a single oral dose of sodium [74As] arsenate to male Wistar rats, arsenic was rapidly absorbed and accumulated in the blood and to a lesser extent in the liver, kidneys, lungs and spleen. Within 1 h of dosing, arsenic was present in the blood, liver and spleen predominantly in the methylated forms (methylarsonic acid and dimethylarsinic acid), whereas in the lung and kidneys, approximately 50% was in the inorganic form. Intravenous injection of sodium [74As] arsenate resulted in a pattern of arsenic species in the blood and kidneys similar to that seen after oral administration, suggesting that the gut flora does not contribute significantly to biotransformation of arsenic in vivo. Analysis of the forms of arsenic in portal blood after administration of arsenate via the small intestine revealed a rapid reduction of arsenate to arsenite, followed by linear rates of production of methylarsonic acid and dimethylarsinic acid.",
Arsenic,1070425,"Arsenic Trioxide Induces Abnormal Mitotic Spindles through a PIP4KII?/Rho Pathway Abstract: Arsenite-induced spindle abnormalities result in mitotic cell apoptosis in several cancer cell lines, but how arsenite induces these effects is not known. Evidence to date has revealed that arsenite activates Rho GTPases. Because Rho GTPases regulate spindle orientation, chromosome congression, and cytokinesis, we therefore examined the involvement of Rho GTPases and their modulators in arsenite-induced mitotic abnormalities. We demonstrated that arsenic trioxide (ATO) disrupted the positioning of bipolar mitotic spindles and induced centrosome and spindle abnormalities. ATO increased the level of the active GTP-bound form of Rho. Inhibition of Rho-associated protein kinases (ROCKs) by Y-27632 ameliorated ATO-induced spindle defects, mitotic arrest, and cell death. These results indicate that ATO may induce spindle abnormalities and mitotic cell death through a Rho/ROCK pathway. In addition, screening of a human kinase and phosphatase shRNA library to select genes that mediate ATO induction of spindle abnormalities resulted in the identification of phosphatidylinositol-5-phosphate 4-kinase type-2 gamma (PIP4KII?), a phosphatidylinositol 4,5-biphosphate (PIP2) synthesis enzyme that belongs to the phosphatidylinositol phosphate kinase (PIPK) family. Sequestration of PIP2 by ectopic overexpression of the pleckstrin homology domain of phospholipase C-?1 protected cells from ATO-induced cell death. Furthermore, depletion of PIP4KII?, but not other isoforms of the PIPK family, not only reduced Rho GTPase activation in ATO-treated cells but also alleviated ATO-induced spindle defects, mitotic arrest, and mitotic cell apoptosis. Thus, our results imply that ATO induces abnormalities in mitotic spindles through a PIP4KII?/Rho pathway, leading to apoptosis of mitotic cells.",
Arsenic,627283,"In vitro DNA damage by arsenic compounds in a human lymphoblastoid cell line (TK6) assessed by the alkaline Comet assay Abstract: Arsenic is classified as a carcinogen for humans, but as a possible genotoxic agent. Thus, taking into account the controversial data about how arsenic compounds are able to induce genetic damage, we investigated the possible genotoxic activity of different arsenic compounds in the TK6 human lymphoblastoid cell line using the alkaline Comet assay. Eight different inorganic and organic arsenical compounds have been selected as follows: three inorganic (sodium arsenite, sodium arsenate and sodium hexafluorarsenate) and five organic (monomethylarsonic and dimethylarsinic acids, arsenobetaine, tetramethylarsonium iodide and tetraphenylarsonium chloride). According to their toxicity and genotoxicity, the highest concentration tested was 10 mM, and the duration of the treatments was 30 min or 3 h. The results indicate that some compounds belonging to both the organic and inorganic species were able to induce significant increases in the tail moment, the parameter used to determine genotoxicity. Thus, the inorganic compounds sodium arsenite and sodium arsenate (but not sodium hexafluoroarsenate) were genotoxic, while among the organoarsenic species tested only tetramethylarsonium iodide and tetraphenylarsonium chloride compounds (but not monomethylarsonic, dimethylarsinic acids and arsenobetaine) induced significant increases in the tail moment. Nevertheless, genotoxic induction was generally only observed at the highest doses tested.",
Arsenic,2278349,"Oxidation of gold-antimony ores by a thermoacidophilic microbial consortium Abstract: Antimony leaching from sulfide ore samples by an experimental consortium of thermoacidophilic microorganisms, including Sulfobacillus, Leptospirillum, and Ferroplasma strains was studied. The ores differed significantly in the content of the major metal sulfides (%): Sb-S, 0.84 to 29.95; Fe-S, 0.47 to 2.5, and As-S, 0.01 to 0.4. Independent of the Sb-S concentration in the experimental sample, after adaptation to a specific ore and pulp compaction, the microorganisms grew actively and leached/oxidized all gold-antimony ores at 39 +/- 1A degrees C. The lower was the content of iron and arsenic sulfides, the higher was antimony leaching. For the first time the investigations conducted with the use of X-ray microanalysis made it possible to conclude that, in a natural high-antimony ore, Sb inhibits growth of only a part of the cell population and that Ca, Fe, and Sb may compete for the binding centers of the cell.",
Arsenic,1016100,"Arsenic affects expression and processing of amyloid precursor protein (APP) in primary neuronal cells overexpressing the Swedish mutation of human APP Abstract: Arsenic poisoning due to contaminated water and soil, mining waste, glass manufacture, select agrochemicals, as well as sea food, affects millions of people world wide. Recently, an involvement of arsenic in Alzheimer's disease (AD) has been hypothesized (Gong and O'Bryant, 2010). The present study stresses the hypothesis whether sodium arsenite, and its main metabolite, dimethylarsinic acid (DMA), may affect expression and processing of the amyloid precursor protein (APP), using the cholinergic cell line SN56.B5.G4 and primary neuronal cells overexpressing the Swedish mutation of APP, as experimental approaches. Exposure of cholinergic SN56.B5.G4 cells with either sodium arsenite or DMA decreased cell viability in a concentration- and exposure-time dependent manner, and affected the activities of the cholinergic enzymes acetylcholinesterase and choline acetyltransferase. Both sodium arsenite and DMA exposure of SN56.B5.G4 cells resulted in enhanced level of APP, and sAPP in the membrane and cytosolic fractions, respectively. To reveal any effect of arsenic on APP processing, the amounts of APP cleavage products, sAPP?, and ?-amyloid (A?) peptides, released into the culture medium of primary neuronal cells derived from transgenic Tg2576 mice, were assessed by ELISA. Following exposure of neuronal cells by sodium arsenite for 12h, the membrane-bound APP level was enhanced, the amount of sAPP? released into the culture medium was slightly higher, while the levels of A? peptides in the culture medium were considerably lower as compared to that assayed in the absence of any drug. The sodium arsenite-induced reduction of A? formation suggests an inhibition of the APP ?-cleavage step by arsenite. In contrast, DMA exposure of neuronal cells considerably increased formation of A? and sAPP?, accompanied by enhanced membrane APP level. The DMA-induced changes in APP processing may be the result of the enhanced APP expression. Alternatively, increased A? production may also be due to stimulation of caspase activity by arsenic compounds, or failure in A? degradation. In summary, the present report clearly demonstrates that sodium arsenite and DMA affect processing of APP in vitro.",1
Arsenic,461486,"Arsenic exposure within the Korean community (United States) based on dietary behavior and arsenic levels in hair, urine, air, and water Abstract: BACKGROUND: Determining arsenic exposure in groups based on geographic location, dietary behaviors, or lifestyles is important, as even moderate exposures may lead to health concerns. OBJECTIVES/METHODS: The Korean community in Washington State, represents a group warranting investigation, as they consume foods (e.g., shellfish, rice, finfish, and seaweed) known to contain arsenic. As part of the Arsenic Mercury Intake Biometric Study, we examined the arsenic levels in hair and urine along with the diets of 108 women of childbearing age from within this community. Arsenic levels in indoor air and drinking water were also investigated, and shellfish commonly consumed were collected and analyzed for total and speciated arsenic. RESULTS: The six shellfish species analyzed (n = 667) contain total arsenic (range, 1-5 ?g/g) but are a small source of inorganic arsenic (range, 0.01-0.12 ?g/g). Six percent of the individuals may have elevated urinary inorganic arsenic levels (> 10 ?g/L) due to diet. Seaweed, rice, shellfish, and finfish are principal sources for total arsenic intake/excretion based on mass balance estimates. Rice consumption (163 g/person/day) may be a significant source of inorganic arsenic. Air and water are not significant sources of exposure. Hair is a poor biometric for examining arsenic levels at low to moderate exposures. CONCLUSIONS: We conclude that a portion of this community may have dietary inorganic arsenic exposure resulting in urine levels exceeding 10 ?g/L. Although their exposure is below that associated with populations exposed to high levels of arsenic from drinking water (> 100 ?g/L), their exposure may be among the highest in the United States.",
Arsenic,627294,"Arsenic species that cause release of iron from ferritin and generation of activated oxygen Abstract: The in vitro effects of four different species of arsenic (arsenate, arsenite, monomethylarsonic acid, and dimethylarsinic acid) in mobilizing iron from horse spleen ferritin under aerobic and anaerobic conditions were investigated. Dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) significantly released iron from horse spleen ferritin either with or without the presence of ascorbic acid, a strong synergistic agent. Ascorbic acid-mediated iron release was time-dependent as well as both DMA(III) and ferritin concentration-dependent. Iron release from ferritin by DMA(III)) alone or with ascorbic acid was not significantly inhibited by superoxide dismutase (150 or 300 units/ml). However, the iron release was greater under anaerobic conditions (nitrogen gas), which indicates direct chemical reduction of iron from ferritin by DMA(III), with or without ascorbic acid. Both DMA(V) and DMA(III)) released iron from both horse spleen and human liver ferritin. Further, the release of ferritin iron by DMA(III)) with ascorbic acid catalyzed bleomycin-dependent degradation of calf thymus DNA. These results indicate that exogenous methylated arsenic species and endogenous ascorbic acid can cause (a) the release of iron from ferritin, (b) the iron-dependent formation of reactive oxygen species, and (c) DNA damage. This reactive oxygen species pathway could be a mechanism of action of arsenic carcinogenesis in man.",
Arsenic,48222,"Effect of parents' occupational exposures on risk of stillbirth, preterm delivery, and small-for-gestational-age infants Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLYVINYL ALCOHOL RUBBER PLASTIC LEAD SYNTHETICS GLASS CLAY STONE TEXTILE MINING INDUSTRIES X-RAYS STATISTICS",
Arsenic,1022085,"Selected Trace Elements in the Sacramento River, California: Occurrence and Distribution Abstract: The impact of trace elements from the Iron Mountain Superfund site on the Sacramento River and selected tributaries is examined. The concentration and distribution of many trace elements-including aluminum, arsenic, boron, barium, beryllium, bismuth, cadmium, cerium, cobalt, chromium, cesium, copper, dysprosium, erbium, europium, iron, gadolinium, holmium, potassium, lanthanum, lithium, lutetium, manganese, molybdenum, neodymium, nickel, lead, praseodymium, rubidium, rhenium, antimony, selenium, samarium, strontium, terbium, thallium, thulium, uranium, vanadium, tungsten, yttrium, ytterbium, zinc, and zirconium-were measured using a combination of inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry. Samples were collected using ultraclean techniques at selected sites in tributaries and the Sacramento River from below Shasta Dam to Freeport, California, at six separate time periods from mid-1996 to mid-1997. Trace-element concentrations in dissolved (ultrafiltered [0.005-?m pore size]) and colloidal material, isolated at each site from large volume samples, are reported. For example, dissolved Zn ranged from 900 ?g/L at Spring Creek (Iron Mountain acid mine drainage into Keswick Reservoir) to 0.65 ?g/L at the Freeport site on the Sacramento River. Zn associated with colloidal material ranged from 4.3 ?g/L (colloid-equivalent concentration) in Spring Creek to 21.8 ?g/L at the Colusa site on the Sacramento River. Virtually all of the trace elements exist in Spring Creek in the dissolved form. On entering Keswick Reservoir, the metals are at least partially converted by precipitation or adsorption to the particulate phase. Despite this observation, few of the elements are removed by settling; instead the majority is transported, associated with colloids, downriver, at least to the Bend Bridge site, which is 67 km from Keswick Dam. Most trace elements are strongly associated with the colloid phase going downriver under both low- and high-flow conditions.",
Arsenic,1019091,"Application of cDNA microarray to the study of arsenic-induced liver diseases in the population of Guizhou, China Abstract: Arsenic is an environmental toxicant and a human carcinogen. Epidemiology studies link human arsenic exposure to various diseases and cancers, including liver diseases and hepatocellular carcinoma. However, the molecular mechanisms for arsenic toxicity and carcinogenicity are poorly understood. To better understand these mechanisms, we used the human cancer cDNA expression array to profile aberrant gene expression in arsenic-exposed populations in Guizhou, China. The selected patients had a history of exposure to environmental arsenic for at least 6-10 years, and had arsenic-induced skin lesions and hepatomegaly. Samples were obtained by liver needle biopsy. Histology showed degenerative liver lesions, such as chronic inflammation, vacuolation, and focal necrosis. The University of North Carolina Hospitals provided normal human liver tissues from surgical resection or rejected transplants. Microarray was performed with total RNA from liver samples, and signal intensities were analyzed with AtlasImage software and normalized with 9 housekeeping genes. Means and SEM were calculated for statistical analysis. Approximately 60 genes (10%) were differentially expressed in arsenic-exposed human livers compared to controls. The differentially expressed genes included those involved in cell-cycle regulation, apoptosis, DNA damage response, and intermediate filaments. The observed gene alterations appear to be reflective of hepatic degenerative lesions seen in the arsenic-exposed patients. This array analysis revealed important patterns of aberrant gene expression occurring with arsenic exposure in human livers. Aberrant expressions of several genes were consistent with the results of array analysis of chronic arsenic-exposed mouse livers and chronic arsenic-transformed rat liver cells. Clearly, a variety of gene expression changes may play an integral role in arsenic hepatotoxicity and possibly carcinogenesis.",
Arsenic,1339174,"Draft genome sequence of Alcaligenes faecalis subsp. faecalis NCIB 8687 (CCUG 2071) Abstract: Alcaligenes faecalis subsp. faecalis NCIB 8687, the betaproteobacterium from which arsenite oxidase had its structure solved and the first arsenate gene island identified, provided a draft genome of 3.9 Mb in 186 contigs (with the largest 15 comprising 90% of the total) for this opportunistic pathogen species.",
Arsenic,2149158,"Toxic compounds in honey Abstract: There is a wealth of information about the nutritional and medicinal properties of honey. However, honey may contain compounds that may lead to toxicity. A compound not naturally present in honey, named 5-hydroxymethylfurfural (HMF), may be formed during the heating or preservation processes of honey. HMF has gained much interest, as it is commonly detected in honey samples, especially samples that have been stored for a long time. HMF is a compound that may be mutagenic, carcinogenic and cytotoxic. It has also been reported that honey can be contaminated with heavy metals such as lead, arsenic, mercury and cadmium. Honey produced from the nectar of Rhododendron ponticum contains alkaloids that can be poisonous to humans, while honey collected from Andromeda flowers contains grayanotoxins, which can cause paralysis of limbs in humans and eventually leads to death. In addition, Melicope ternata and Coriaria arborea from New Zealand produce toxic honey that can be fatal. There are reports that honey is not safe to be consumed when it is collected from Datura plants (from Mexico and Hungary), belladonna flowers and Hyoscamus niger plants (from Hungary), Serjania lethalis (from Brazil), Gelsemium sempervirens (from the American Southwest), Kalmia latifolia, Tripetalia paniculata and Ledum palustre. Although the symptoms of poisoning due to honey consumption may differ depending on the source of toxins, most common symptoms generally include dizziness, nausea, vomiting, convulsions, headache, palpitations or even death. It has been suggested that honey should not be considered a completely safe food. Copyright © 2013 John Wiley &amp; Sons, Ltd.",
Arsenic,1251007,"Physiological response of Desulfurispirillum indicum S5 to arsenate and nitrate as terminal electron acceptors Abstract: The ability of anaerobic prokaryotes to employ different terminal electron acceptors for respiration enables these organisms to flourish in subsurface ecosystems. Desulfurispirillum indicum strain S5 is an obligate anaerobic bacterium that is able to grow by respiring a range of different electron acceptors, including arsenate and nitrate. Here, we examined the growth, electron acceptor utilization, and gene expression of D. indicum growing under arsenate and nitrate-reducing conditions. Consistent with thermodynamic predictions, the experimental results showed that the reduction of nitrate to ammonium yielded higher cell densities than the reduction of arsenate to arsenite. However, D. indicum grew considerably faster by respiration on arsenate compared with nitrate, with doubling times of 4.3 ± 0.2 h and 19.2 ± 2.0 h, respectively. Desulfurispirillum indicum growing on both electron acceptors exhibited the preferential utilization of arsenate before nitrate. The expression of the arsenate reductase gene arrA was up-regulated approximately 100-fold during arsenate reduction, as determined by qRT-PCR. Conversely, the nitrate reductase genes narG and napA were not differentially regulated under the conditions tested. The results of this study suggest that physiology, rather than thermodynamics, controls the growth rates and hierarchy of electron acceptor utilization in D. indicum.",
Arsenic,626938,"Carcinogen exposure and epigenetic silencing in bladder cancer Abstract: Tobacco smoking, certain occupational exposures, and exposure to inorganic arsenic in drinking water have been associated with the occurrence of bladder cancer. However, in these tumors the exposure-associated pattern of somatic alterations in genes in the causal pathway for disease has been poorly characterized. Animal and in vitro studies have suggested that arsenic, tobacco carcinogens, and other exposures may act through epigenetic mechanisms. We, therefore, examined, in a population-based study of human bladder cancer (n = 351), the relationship between epigenetic silencing of the tumor-suppressor genes, p16(INK4A), RASSF1A, PRSS3, and the four SFRP genes and exposure to both tobacco and arsenic in bladder cancer. Promotor methylation silencing of each of these genes occurred in approximately 30-50% of bladder cancers. Epigenetic silencing of RASSF1A and PRSS3 and any of the SFRP genes were each significantly associated with advanced tumor stage (P < 0.001, P < 0.04, and P < 0.005, respectively). Arsenic exposure, measured as toenail arsenic, was associated with RASSF1A (P < 0.02) and PRSS3 (P < 0.1) but not p16(INK4A) or SFRP promotor methylation, in models adjusted for stage and other risk factors. Cigarette smoking was associated with a greater than twofold increased risk of promotor methylation of the p16(INK4A) gene, with greater risk seen in patients with exposures more recent to disease diagnosis, and smoking was also significantly associated with any SFRP gene methylation (P < 0.01). These results from human bladder tumors, add to the body of animal and in vitro evidence that suggests bladder carcinogens play a crucial role in the induction of important epigenetic alterations.",
Arsenic,628031,"Childhood cancer incidence and arsenic exposure in drinking water in Nevada Abstract: Inorganic arsenic exposure through drinking water causes cancer in adults; however, the carcinogenic potential in children remains unknown. A recent leukemia cluster in Churchill County, Nevada, where arsenic levels in water supplies are relatively high, has prompted concern. The authors investigated the incidence of childhood cancer between 1979 and 1999 in all 17 Nevada counties, grouped by low (i.e., < 10 microg/l), medium (10-25 microg/l), and high (35-90 microg/l) population-weighted arsenic levels in public drinking water supplies. The standardized incidence ratios (SIRs) for all childhood cancers combined were 1.00 (95% confidence interval [CI] = 0.94, 1.06), 0.72 (95% CI = 0.43, 1.12), and 1.25 (95% CI = 0.91, 1.69) for low-, medium-, and high-exposure counties, respectively. There was no relationship between arsenic levels in water and childhood leukemia (SIRs = 1.02, 0.61, and 0.86, respectively [95% CIIs = 0.90, 1.15; 0.12, 1.79; and 0.37, 1.70, respectively]). For all childhood cancers, excluding leukemias, the SIRs were 0.99 (95% CI = 0.92, 1.07), 0.82 (95% CI = 0.42, 1.22), and 1.37 (0.92, 1.83), respectively. The excess in 5- to 9-yr-old children and 10- to 14-yr-old children was in bone cancers, and the excess in 15- to 19-yr-old young adults was primarily in lymphomas. The findings in this study are reassuring in that leukemia risks were not increased at the concentrations of arsenic in water found in this study. Nonetheless, the results raise the possibility that there are increased risks for nonleukemic childhood cancers that require confirmation in other studies, particularly those in which higher exposures are addressed.",
Arsenic,1016896,"Determination of arsenic in homeopathic drugs by bromide volatilization-inductively coupled plasma-atomic emission spectrometry Abstract: Arsenic in homeopathic drugs was determined by coupling a volatile generation with inductively coupled plasma-atomic emission spectrometry. The method is based on the chemical vaporization of arsenic(III) with bromide ions in sulfuric acid media using a batch procedure and subsequent introduction of the gaseous analyte into the plasma torch. The main and interactive effects of the experimental variables affecting this method were evaluated by a 2-level full factorial design. In optimized conditions by Simplex, the method shows an absolute detection limit (3 s) of 0.28 microg for the injection of 230 microL sample. The precision (% relative standard deviation) of the determination was 4.2% at a level of 50 microg/mL As(III) (n = 5). The interference effect of various ions on the arsenic signal was evaluated.",
Arsenic,1347901,"Enhancement of stress-induced synthesis of hsp27 and alpha B crystallin by modulators of the arachidonic acid cascade Abstract: The regulation by intrinsic factors of responses to stress of two small stress proteins, hsp27 and alpha B crystallin, was examined in C6 rat glioma cells. Levels of hsp27 and alpha B crystallin were low in C6 glioma cells in confluent cultures. However, levels of the two proteins increased after exposure of cells to heat (42 degrees C for 30 min) or arsenite (50 microM for 1 h) stress. When cells were exposed to arsenite or hear in the presence of indomethacin (50 microM), an inhibitor of cyclooxygenase, or in the presence of nordihydroguaiaretic acid (NDGA; 50 microM), an inhibitor of lipoxygenase, induction of hsp27 and alpha B crystallin was markedly stimulated as detected by specific immunoassays, Western blot analysis, and Northern blot analysis. The presence of melittin (1 microM), an activator of phospholipase A2, during the stress period also stimulated the induction of the two proteins. The expression of hsp70 to each stress was also enhanced in the presence of indomethacin, NDGA, or melittin. The gel mobility shift assay revealed that these chemicals prolonged the arsenite-induced activation of heat shock element (HSE)-binding activity of heat shock transcriptional factor (HSF) in cells. Induction of hsp27 and alpha B crystallin in adrenal glands of heat-stressed (42 degrees C for 15 min) rats was also enhanced by prior injection of aspirin, another inhibitor of cyclooxygenase. These results indicate that the responses to stress of hsp27 and alpha B crystallin, as well as the response of hsp70, are coupled with the metabolic activity of the arachidonic acid cascade and the mechanism for regulation of stress responses observed in C6 cells is operative in tissues and organs in vivo.",
Arsenic,133280,"Keratinocyte Differentiation Marker Suppression by Arsenic: Mediation by AP1 Response Elements and Antagonism by Tetradecanoylphorbol Acetate Abstract: Culture models of target cells are anticipated to help elucidate the mechanism by which inorganic arsenic acts as a carcinogen in humans. Present work characterizes the response of human keratinocytes, a target cell type, to arsenic suppression of their differentiation program. Four representative differentiation marker mRNAs (involucrin, keratinocyte transglutaminase, small proline-rich protein 1, and filaggrin) were suppressed by both arsenate and arsenite in normal, spontaneously immortalized (premalignant), and malignant keratinocytes with EC50 values in the low micromolar range. The suppression was almost completely reversed 9 days after removal of arsenate from the culture medium. In the case of the involucrin gene, suppression was mediated primarily by two functional AP1 response elements in the gene promoter. Both glucocorticoid and serum stimulation of differentiation occurred to a similar extent in the presence and absence of arsenic, indicating neither stimulation was a specific target of arsenic action and neither agent could overcome arsenic suppression. In contrast, 12-O-tetradecanoylphorbol-13-acetate prevented the suppression of keratinocyte transglutaminase, suggesting that arsenic acts upstream of protein kinase C.",
Arsenic,627218,"Comparison of health effects between individuals with and without skin lesions in the population exposed to arsenic through drinking water in West Bengal, India Abstract: A study was conducted to explore the effect of arsenic causing conjunctivitis, neuropathy and respiratory illness in individuals, with or without skin lesions, as a result of exposure through drinking water, contaminated with arsenic to similar extent. Exposed study population belongs to the districts of North 24 Parganas and Nadia, West Bengal, India. A total of 725 exposed (373 with skin lesions and 352 without skin lesions) and 389 unexposed individuals were recruited as study participants. Participants were clinically examined and interviewed. Arsenic content in drinking water, urine, nail and hair was estimated. Individuals with skin lesion showed significant retention of arsenic in nail and hair and lower amount of urinary arsenic compared to the group without any skin lesion. Individuals with skin lesion also showed higher risk for conjunctivitis ((odd's ratio) OR: 7.33, 95% CI: 5.05-10.59), peripheral neuropathy (OR: 3.95, 95% CI: 2.61-5.93) and respiratory illness (OR: 4.86, 95% CI: 3.16-7.48) compared to the group without any skin lesion. The trend test for OR of the three diseases in three groups was found to be statistically significant. Again, individuals without skin lesion in the exposed group showed higher risk for conjunctivitis (OR: 4.66, 95% CI: 2.45-8.85), neuropathy (OR: 3.99, 95% CI: 1.95-8.09), and respiratory illness (OR: 3.21, 95% CI: 1.65-6.26) when compared to arsenic unexposed individuals. Although individuals with skin lesions were more susceptible to arsenic-induced toxicity, individuals without skin lesions were also subclinically affected and are also susceptible to arsenic-induced toxicity and carcinogenicity when compared to individuals not exposed to arsenic.",
Arsenic,2279225,"Structural and topological control on physical properties of arsenic selenide glasses Abstract: The structures of Ge-doped arsenic selenide glasses with Se contents varying between 25 and 90 at. % are studied using a combination of high-resolution, two-dimensional (77)Se nuclear magnetic resonance (NMR) and Raman spectroscopy. The results indicate that, in contrast to the conventional wisdom, the compositional evolution of the structural connectivity in Se-excess glasses does not follow the chain-crossing model, and chemical order is likely violated with the formation of a small but significant fraction of As-As bonds. The addition of As to Se results in a nearly random cross-linking of Se chains by AsSe3 pyramids, and a highly chemically ordered network consisting primarily of corner-shared AsSe3 pyramids is formed at the stoichiometric composition. Further increase in As content, up to 40 at. % Se, results in the formation of a significant fraction of As4Se3 molecules with As-As homopolar bonds, and consequently the connectivity and packing efficiency of the network decrease and anharmonic interactions increase. Finally, in the highly As-rich region with &lt;40 at. % Se, the relative concentration of the As4Se3 molecules decreases rapidly and large clusters of As atoms connected via Se-Se-As and As-Se-As linkages dominate. These three composition regions with distinct structural characteristics and the corresponding mixing entropy of the Se environments are reflected in the appearance of multiple extrema in the compositional variation of a wide range of physical properties of these glasses, including density, glass transition temperature, thermal expansivity, and fragility.",
Arsenic,1251613,"Preimplantation mouse embryos express a heat-stable alkaline phosphatase Abstract: The cell surface alkaline phosphatase (APase) of the preimplantation mouse embryo has been characterized in situ by inhibition studies and fluorescent histochemistry. The embryonic APase has also been compared in the inhibition studies to the APase expressed on mouse F9 teratocarcinoma cells and, in some instances, to the APase of mouse intestinal epithelial cells. The embryonic APase was active over the pH range of 6.0-10.0, with the optimal pH for full activity in the range of 8.5-10.0. The embryonic APase was remarkably heat stable with significant loss of activity detected only after a 1 h incubation at 90 degrees C. A variety of specific and nonspecific APase inhibitors were applied to embryos to determine the nature of the APase isozymes expressed on these cells. The embryonic APase was totally resistant to levamisole, tetramisole, bromotetramisole, and L-homoarginine. The embryonic APase was inhibited by L-phenylalanine in a concentration-dependent fashion and by sodium arsenate, sodium vanadate, ethylenediamine tetraacetic acid, and slightly by 1,10-phenanthroline. The inhibition profile of the mouse embryonic APase, therefore, resembles most closely that reported for human placental APase with respect to heat stability and that reported for mouse intestinal APase with respect to inhibitor sensitivity.",
Arsenic,1936058,"Reaction of small heat-shock proteins to different kinds of cellular stress in cultured rat hippocampal neurons Abstract: Upregulation of small heat-shock proteins (sHsps) in response to cellular stress is one mechanism to increase cell viability. We previously described that cultured rat hippocampal neurons express five of the 11 family members but only upregulate two of them (HspB1 and HspB5) at the protein level after heat stress. Since neurons have to cope with many other pathological conditions, we investigated in this study the expression of all five expressed sHsps on mRNA and protein level after sublethal sodium arsenite and oxidative and hyperosmotic stress. Under all three conditions, HspB1, HspB5, HspB6, and HspB8 but not HspB11 were consistently upregulated but showed differences in the time course of upregulation. The increase of sHsps always occurred earlier on mRNA level compared with protein levels. We conclude from our data that these four upregulated sHsps (HspB1, HspB5, HspB6, HspB8) act together in different proportions in the protection of neurons from various stress conditions.",
Arsenic,2345654,"Higher urinary heavy metal, arsenic, and phthalate concentrations in people with high blood pressure: US NHANES, 2009-2010 Abstract: Background: A link between environmental chemicals and human health has emerged but not complete in risk factors. This work aimed to study the relationships of different sets of urinary environmental chemical concentrations and risk of high blood pressure (BP) in a national, population-based study. Methods: Data was retrieved from United States National Health and Nutrition Examination Surveys, 2009-2010, including demographics, BP readings and urinary environmental chemical concentrations. Analyses included t-test and survey-weighted logistic regression models. Results: Urinary mercury concentrations were not associated with high BP (OR = 1.19, 95% CI 0.97-1.48, p = 0.095). Urinary cobalt (OR = 1.35, 95% CI 1.01-1.81, p = 0.044), lead (OR = 1.77, 95% CI 1.31-2.38, p = 0.001), antimony (OR = 1.37, 95% CI 1.09-1.72, p = 0.010) and tungsten (OR = 1.52, 95% CI 1.27-1.81, p &lt; 0.001) concentrations were observed to increase the risk of high BP. There are no clear associations between environmental parabens and high BP. The effect of environmental bisphenol A (OR = 1.14, 95% CI 1.00-1.30, p = 0.051) disappeared after additionally adjusting for subsample weighting (OR = 1.12, 95% CI 0.93-1.35, p = 0.225). People with higher urinary mono-2-ethyl-5-carboxypentyl phthalate (OR = 1.26, 95% CI 1.00-1.58, p = 0.051), mono-n-butyl phthalate (OR = 1.19, 95% CI 1.01-1.41, p = 0.042) and mono-n-methyl phthalate metabolites (OR = 1.16, 95% CI 1.03-1.32, p = 0.021) tended to have high BP. Moreover, urinary o-phenyl phenol concentrations (OR = 1.49, 95% CI 1.25-1.77, p &lt; 0.001) and dimethylarsonic acid concentrations (OR = 1.35, 95% CI 1.06-1.73, p = 0.019) were also seen to be associated with high BP. Conclusions: Urinary environmental chemical concentrations were associated with risk of high BP, although the causal effect cannot be established. Elimination of environmental chemicals in humans would need to be continued.",
Arsenic,345063,"Revised and new reference values for arsenic, cadmium, lead and mercury in blood or urine of children: Basis for validation of human biomonitoring data in environmental medicine Abstract: Reference values for environmental pollutants in the German population are established continuously by the Human Biomonitoring Commission of the German Federal Environmental Agency. The reference values (defined as 95th percentile) are usually derived from results of the German Environmental Surveys (GerES). However, current reference values for children are lacking since GerES II conducted in 1990/92 and additionally the first German Environmental Survey on Children (GerES IV) will not be finished until the end of 2006. As an interim solution, the commission derived in 2005 reference values for children aged 6–12 years from a survey performed in south-west Germany in 2002/03 (508 children) and the pilot study for GerES IV 2001/2002 (252 children). A new reference value of 15 mg/l for children was derived for arsenic in urine. The reference values for cadmium in whole blood (0.5 mg/l) and for cadmium in urine (0.5 mg/l) were confirmed. The following reference values were lowered: for lead in blood from 60 to 50 mg/l, for mercury in whole blood from 1.5 to 1.0 mg/l and for mercury in urine from 1.4 to 0.7 mg/l.",
Arsenic,1337339,"Arsenic-mediated activation of the Nrf2-Keap1 antioxidant pathway Abstract: Arsenic is present in the environment and has become a worldwide health concern due to its toxicity and carcinogenicity. However, the specific mechanism(s) by which arsenic elicits its toxic effects has yet to be fully elucidated. The transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) has been recognized as the master regulator of a cellular defense mechanism against toxic insults. This review highlights studies demonstrating that arsenic activates the Nrf2-Keap1 antioxidant pathway by a distinct mechanism from that of natural compounds such as sulforaphane (SF) found in broccoli sprouts or tert-butylhyrdoquinone (tBHQ), a natural antioxidant commonly used as a food preservative. Evidence also suggests that arsenic prolongs Nrf2 activation and may mimic constitutive activation of Nrf2, which has been found in several human cancers due to disruption of the Nrf2-Keap1 axis. The current literature strongly suggests that activation of Nrf2 by arsenic potentially contributes to, rather than protects against, arsenic toxicity and carcinogenicity. The mechanism(s) by which known Nrf2 activators, such as the natural chemopreventive compounds SF and lipoic acid, protect against the deleterious effects caused by arsenic will also be discussed. These findings will provide insight to further understand how arsenic promotes a prolonged Nrf2 response, which will lead to the identification of novel molecular markers and development of rational therapies for the prevention or intervention of arsenic-induced diseases. The National Institute of Environmental Health Science (NIEHS) Outstanding New Environmental Scientist (ONES) award has provided the opportunity to review the progress both in the fields of arsenic toxicology and Nrf2 biology. Much of the funding has led to (1) the novel discovery that arsenic activates the Nrf2 pathway by a mechanism different to that of other Nrf2 activators, such as sulforaphane and tert-butylhydroquinone, (2) activation of Nrf2 by chemopreventive compounds protects against arsenic toxicity and carcinogenicity both in vitro and in vivo, (3) constitutive activation of Nrf2 by disrupting Keap1-mediated negative regulation contributes to cancer and chemoresistance, (4) p62-mediated sequestration of Keap1 activates the Nrf2 pathway, and (5) arsenic-mediated Nrf2 activation may be through a p62-dependent mechanism. All of these findings have been published and are discussed in this review. This award has laid the foundation for my laboratory to further investigate the molecular mechanism(s) that regulate the Nrf2 pathway and how it may play an integral role in arsenic toxicity. Moreover, understanding the biology behind arsenic toxicity and carcinogenicity will help in the discovery of potential strategies to prevent or control arsenic-mediated adverse effects.",
Arsenic,1509344,Industrial contamination of alluvial soils near Fe-Pb mining site revealed by magnetic and geochemical studies Abstract: ,
Arsenic,2279532,"A vibrational spectroscopic study of the arsenate minerals cobaltkoritnigite and koritnigite Abstract: Raman spectra of two well-defined types of cobaltkoritnigite and koritnigite crystals were recorded and interpreted. Significant differences in the Raman spectra of cobaltkoritnigite and koritnigite were observed. Observed Raman bands were attributed to the (AsO3OH)(2-) stretching and bending vibrations, stretching and bending vibrations of water molecules and hydroxyl ions. Both Raman and infrared spectra of cobaltkoritnigite identify bands which are attributable to phosphate and hydrogen phosphate anions proving some substitution of phosphate for arsenate in the structure of cobaltkoritnigite. The OH?O hydrogen bond lengths in the crystal structure of koritnigite were inferred from the Raman spectra and compared with those derived from the X-ray single crystal refinement. The presence of (AsO3OH)(2-) units in the crystal structure of cobaltkoritnigite and koritnigite was proved from the Raman spectra which supports the conclusions of the X-ray structure analysis.",
Arsenic,628383,"Case-control study of bladder cancer and drinking water arsenic in the western United States Abstract: Numerous epidemiologic investigations have identified links between high concentrations of arsenic in drinking water and cancer, although the risks at lower exposures are largely unknown. This paper presents the results of a case-control study of arsenic ingestion and bladder cancer in seven counties in the western United States. These counties contain the largest populations historically exposed to drinking water arsenic at concentrations near 100 µg/liter. All incident cases diagnosed from 1994 to 2000 were recruited. Individual data on water sources, water consumption patterns, smoking, and other factors were collected for 181 cases and 328 controls. Overall, no increased risks were identified for arsenic intakes greater than 80 µg/day (odds ratio = 0.94, 95% confidence interval: 0.56, 1.57; linear trend, p = 0.48). These risks are below predictions based on high dose studies from Taiwan. When the analysis was focused on exposures 40 or more years ago, an odds ratio of 3.67 (95% confidence interval: 1.43, 9.42; linear trend, p < 0.01) was identified for intakes greater than 80 µg/day (median intake, 177 µg/day) in smokers. These data provide some evidence that smokers who ingest arsenic at concentrations near 200 µg/day may be at increased risk of bladder cancer.",
Arsenic,2347715,"A monitoring of chemical contaminants in waters used for field irrigation and livestock watering in the Veneto region (Italy), using bioassays as a screening tool Abstract: In this study, 50 livestock watering sources (ground water) and 50 field irrigation sources (surface water) from various industrialised areas of the Veneto region were monitored for chemical contaminants. From each site, four water samples (one in each season) were collected during the period from summer 2009 through to spring 2010. Surface water samples and ground water samples were first screened for toxicity using the growth inhibition test on Pseudokirchneriella subcapitata and the immobilisation test on Daphnia magna, respectively. Then, based on the results of these toxicity tests, 28 ground water samples and 26 surface water samples were submitted to chemical analysis for various contaminants (insecticides/acaricides, fungicides, herbicides, metals and anions) by means of UPLC-MS(n) HPLC-MS(n), AAS and IEC. With the exception of one surface water sample where the total pesticides concentration was greater than 4 ?g L(-1), positive samples (51.9 %) showed only traces (nanograms per liter) of pesticides. Metals were generally under the detection limit. High concentrations of chlorines (up to 692 mg L(-1)) were found in some ground water samples while some surface water samples showed an excess of nitrites (up to 336 mg L(-1)). Detected levels of contamination were generally too low to justify the toxicity recorded in bioassays, especially in the case of surface water samples, and analytical results painted quite a reassuring picture, while tests on P. subcapitata showed a strong growth inhibition activity. It was concluded that, from an ecotoxicological point of view, surface waters used for field irrigation in the Veneto region cannot be considered safe.",
Arsenic,1597301,"The role of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in arsenic bioleaching from soil Abstract: Bioleaching of As from the soil in an abandoned Ag-Au mine was carried out using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A. ferrooxidans is an iron oxidizer and A. thiooxidans is a sulfur oxidizer. These two microbes are acidophilic and chemoautotrophic microbes. Soil samples were collected from the Myoungbong and Songcheon mines. The main contaminant of the soil was As, with an average concentration of 4,624 mg/kg at Myoungbong and 5,590 mg/kg at Songcheon. A. ferrooxidans and A. thiooxidans generated lower pH conditions during their metabolism process. The bioleaching of As from soil has a higher removal efficiency than chemical leaching. A. ferrooxidans could remove 70 % of the As from the Myoungbong and Songcheon soils; however, A. thiooxidans extracted only 40 % of the As from the Myoungbong soil. This study shows that bioleaching is an effective process for As removal from soil.",
Arsenic,1024684,"Oxidative stress and antioxidant defenses in goldfish liver in response to short-term exposure to arsenite Abstract: Arsenic is an environmental pollutant capable of causing oxidative stress, disturbance of metabolism, and cancer development. The present study was undertaken to investigate the effects of exposure to sodium arsenite on the glutathione pool, lipid peroxidation, protein carbonyl levels, global DNA methylation, and activities of six antioxidant enzymes in goldfish liver. In a preliminary experiment, 7-day exposure to 200 microM sodium arsenite, but not 10 or 100 microM, disturbed the glutathione status. A detailed investigation of oxidative stress development and antioxidant responses was further examined during different periods of exposure to 200 microM sodium arsenite. This treatment increased lipid peroxide levels after 1 and 4 days of exposure but did not affect thiobarbituric acid reactive substances and protein carbonyls. Oxidized glutathione and the oxidative stress index rose after 4 days, but de novo glutathione synthesis decreased both parameters after 7 days. Activities of the main antioxidant enzymes-superoxide dismutase, catalase, and glutathione peroxidase, were elevated after longer periods of exposure, indicating an enhanced antioxidant response. Arsenite exposure led to DNA hypomethylation, which is an early marker of disturbed epigenetic regulations. The findings suggest that goldfish livers cope with arsenic-induced oxidative stress mainly through adaptive changes in the glutathione pool and antioxidant enzymes.",
Arsenic,2149258,"UPTAKE AND TOXICITY OF ARSENIC, COPPER, AND SILICON IN AZOLLA CAROLINIANA AND LEMNA MINOR Abstract: Here we report on the analysis of two aquatic plant species, Azolla caroliniana and Lemna minor, with respect to tolerance and uptake of co-occurring arsenic, copper, and silicon for use in engineered wetlands. Plants were cultured in nutrient solution that was amended with arsenic (0 or 20 microM), copper (2 or 78 microM), and silicon (0 or 1.8 mM) either singly or in combination. We hypothesized that arsenic and copper would negatively affect the uptake of metals, growth, and pigmentation and that silicon would mitigate those stresses. Tolerance was assessed by measuring growth of biomass and concentrations of chlorophyll and anthocyanins. Both plant species accumulated arsenic, copper, and silicon; L. minor generally had higher levels on a per biomass basis. Arsenic negatively impacted A. caroliniana, causing a 30% decrease in biomass production and an increase in the concentration of anthocyanin. Copper negatively impacted L. minor, causing a 60% decrease in biomass production and a 45% decrease in chlorophyll content. Silicon augmented the impact of arsenic on biomass production in A. caroliniana but mitigated the effect of copper on L. minor. Our results suggest that mixtures of plant species may be needed to maximize uptake of multiple contaminants in engineered wetlands.",
Arsenic,2337193,"The effect of arsenic on some antioxidant enzyme activities and lipid peroxidation in various tissues of mirror carp (Cyprinus carpio carpio) Abstract: The effect of arsenic bioaccumulation in liver, kidney, skin, muscle, and intestinal tissues of mirror carp (Cyprinus carpio carpio) was investigated on lipid peroxidation and certain antioxidant enzyme activities. In this study, three aquarium groups were formed from mirror carp: control group, 0.5-, and 1-mg/L arsenic concentrations. The fish were dissected after 1 month. Arsenic bioaccumulation, malondialdehyde (MDA) levels, catalase (CAT), and superoxide dismutase (SOD) enzyme activities were determined in the tissues. Results showed that arsenic was accumulated in liver, kidney, muscle, skin, and intestinal tissues. As the final product of lipid peroxidation, MDA levels were determined to have increased in all tissues with the exception of muscle. On the other hand, CAT and SOD enzyme activities in the fish tissues were decreased as compared to the control group. In the muscle tissue, differences were observed in the enzyme activities depending on arsenic concentration. Considering the increases in enzyme inhibition and MDA levels, liver was observed to be the main tissue affected in response to the arsenic toxicity.",
Arsenic,1070326,"Leaching characteristics of CCA-treated wood waste: A UK study Abstract: CCA-treated wood is expected to increase in the UK waste stream over the next 20-50years. The potential pollution from this waste has been evaluated through two leaching studies, one based upon batch leaching tests and another based upon a series of lysimeter tests. The aim of the studies was to characterise the behaviour of arsenic (As), chromium (Cr) and copper (Cu) from this wood when applied to soil as a mulch. Results demonstrate that all three elements leach from CCA waste wood, occasionally in concentrations exceeding regulatory thresholds by two to three orders of magnitude. In the lysimeter study, wood mulch monofills and wood mulch in combination with soil were used to monitor the leaching of As, Cr and Cu. Peak concentrations for As, Cr and Cu were 1885?g/l, 1243?g/l and 1261?g/l, respectively. Freshly treated wood leached 11, 23 and 33 times more Cu, Cr and As, respectively than weathered wood. The toxic and mobile species of arsenic (As III, As V) were detected. Leaching in the CCA wood monofill was influenced by rainfall, with higher concentrations of metal(loid)s produced in lower intensity events. As and Cu were mobilised preferentially, with all metals exhibiting similar temporal trends. Retention of leached metal(loid)s was observed in lysimeters containing soil. Leaching processes appear to be favoured by the chipping process, diffusion and weathering. This study has shown that weathered waste wood mulch can cause significant pollution in soil water with potential impacts on both the environment and human health.",
Arsenic,1579406,"Particle-size effects on dissolved arsenic adsorption to an Australian laterite Abstract: In this study, arsenic adsorption to an Australian laterite has been examined for a particle-size range between 38 ?m and 25 mm. The results show that particle size influences both kinetic and equilibrium characteristics of arsenic adsorption. The equilibrium adsorption capacity increases from around 100 mg kg?1 for laterite particles coarser than 4 mm, to around 160 mg kg?1 for laterite particles between 75 ?m and 4 mm, and to over 200 mg kg?1 for laterite particles finer than 75 ?m. The kinetic adsorption data can be fitted with the pseudo-second-order reaction model, in particular for finer particles where the film diffusion and/or surface reaction are important processes. The model-fitted rate constant remains steady for laterite particles coarser than 2 mm, increases moderately with particle size in the range between 75 ?m and 2 mm, and increases dramatically for laterite particles finer than 75 ?m. These arsenic adsorption behaviours can be explained by the relative importance of two particle-size-dependent processes: quick external-surface adsorption (more important for fine particles) and slow intraparticle adsorption (more important for coarse particles). Most of the external-surface adsorption completes in the first hour of the experiment. To apply the studied laterite for dissolved arsenic removal, it is recommended that fine particles, in particular finer than 75 ?m, should be used if the contact time is the limitation, and that coarse particles, in particular 2–4 mm, should be used if sufficient contact time is available.",
Arsenic,1351577,"ACCUMULATION AND LOSS OF ARSENIC AND BORON, ALONE AND IN COMBINATION, IN MALLARD DUCKS Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenic and boron are common in the environment, and wildlife can be exposed to toxic concentrations through both natural and human-influenced processes. We exposed adult male mallard ducks to dietary concentrations of 300 ppm arsenic as sodium arsenate, 1,600 ppm boron as boric acid, or both and estimated the tissue accumulation and loss rates when the ducks were returned to uncontaminated food. Both elements were accumulated rapidly; equilibrium levels were reached for arsenic in 10 to 30 d and for boron in 2 to 15 d. Accumulation of each element was slowed by the presence of the other in the diet. Boron was eliminated by mallards very rapidly, with few detectable residues \ 1 d after removal of boron from the diet; arsenic was also rapidly lost with half-lives of I to 3 d (half-lives were not constant throughout the loss period). Arsenic loss rate was not affected by the presence of boron. Arsenic accumulated to the highest level in liver tissue, with blood and brain",
Arsenic,1936050,"Arsenic induces the expressions of angiogenesis-related factors through PI3K and MAPK pathways in SV-HUC-1 human uroepithelial cells Abstract: Arsenic, a well-established human carcinogen, can cause various types of cancers, including bladder cancer. Angiogenesis is a key event for tumor initiation. In this study, several important angiogenesis related factors, including cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1? (HIF-1?), were up-regulated and PI3K/AKT and MAPK signal pathways were activated in human uroepithelial cell line (SV-HUC-1) treated with NaAsO2 (0, 1, 2, 4, 8 or 10?M) for 24h. Arsenite-induced HIF-1?, VEGF and COX-2 expressions were decreased by PI3K inhibitors. Blockage of the ERK1/2, p38 and JNK down-regulated the VEGF level, while ERK1/2 and p38 inhibitors were more effective than JNK in attenuating arsenite-induced COX-2 expression. HIF-1? expression was only decreased by ERK1/2 inhibitor. It was found that superoxide (O2(-)) generation was involved in arsenite-induced the activation of MAPK and PI3K pathways, which led to the HIF-1?, COX-2 and VEGF overexpressions. In conclusion, arsenite-induced COX-2, VEGF and HIF-1? expressions, mediated partially by reactive oxygen species (ROS), were regulated by MAPK and PI3K/AKT signaling pathways in human uroepithelial cells.",
Arsenic,1329993,"Expression of the small heat shock protein gene, hsp30, in Rana catesbeiana fibroblasts Abstract: In the present study, we examined the expression of the Rana catesbeiana small heat shock protein gene, hsp30, in an FT fibroblast cell line. Northern and western blot analyses revealed that hsp30 mRNA or HSP30 protein was not present constitutively but was strongly induced at a heat shock temperature of 35 degrees C. However, treatment of FT cells with sodium arsenite at concentrations that induced hsp gene expression in other amphibian systems caused cell death. Non-lethal concentrations of sodium arsenite (10 microM) induced only minimal accumulation of hsp30 mRNA or protein after 12 h. Immunocytochemical analyses employing laser scanning confocal microscopy detected the presence of heat-inducible HSP30, in a granular or punctate pattern. HSP30 was enriched in the nucleus with more diffuse localization in the cytoplasm. The nuclear localization of HSP30 was more prominent with continuous heat shock. These heat treatments did not alter FT cell shape or disrupt actin cytoskeletal organization. Also, HSP30 did not co-localize with the actin cytoskeleton.",
Arsenic,1519216,The pH dependence of phosphate sorption and desorption in Swedish agricultural soils Abstract: ,
Arsenic,627925,"A market basket survey of inorganic arsenic in food Abstract: Dietary arsenic intake estimates based on surveys of total arsenic concentrations appear to be dominated by intake of the relatively non-toxic, organic arsenic forms found in seafood. Concentrations of inorganic arsenic in food have not been not well characterized. Accurate dietary intake estimates for inorganic arsenic are needed to support studies of arsenic's status as an essential nutrient, and to establish background levels of exposure to inorganic arsenic. In the market basket survey reported here, 40 commodities anticipated to provide at least 90% of dietary inorganic arsenic intake were identified. Four samples of each commodity were collected. Total arsenic was analysed using an NaOH digestion and inductively coupled plasma-mass spectrometry. Separate aliquots were analysed for arsenic species using an HCl digestion and hydride atomic absorption spectroscopy. Consistent with earlier studies, total arsenic concentrations (all concentrations reported as elemental arsenic per tissue wet weight) were highest in the seafoods sampled (ranging from 160 ng/g in freshwater fish to 2360 ng/g in saltwater fish). In contrast, average inorganic arsenic in seafood ranged from less than 1 ng/g to 2 ng/g. The highest inorganic arsenic values were found in raw rice (74 ng/g), followed by flour (11 ng/g), grape juice (9 ng/g) and cooked spinach (6 ng/g). Thus, grains and produce are expected to be significant contributors to dietary inorganic arsenic intake.",
Arsenic,628677,"Micromolar concentrations of sodium arsenite induce cyclooxygenase-2 expression and stimulate p42/44 mitogen-activated protein kinase phosphorylation in normal human epidermal keratinocytes Abstract: Based on evidence that arsenic modulates proinflammatory events that are involved in skin carcinogenecity, we hypothesized that in normal human epidermal keratinocytes (NHEK) arsenic increases expression of the procarcinogenic enzyme cyclooxygenase-2 (COX-2) and that this occurs via specific mitogen and stress signaling pathways. To test this hypothesis, NHEK were exposed to sodium arsenite, and COX-2 expression, prostaglandin E2 (PGE2) secretion, mitogen-activated protein kinase (MAPK) phosphorylation, and DNA synthesis were quantified. Inhibitors of p42/44 and p38 MAPKs were used to evaluate the contribution of mitogen and stress signaling to the modulation of COX-2. Our results demonstrate that arsenite (0.005–5 µM) elevates COX-2 expression, PGE2 secretion (2.5–5 µM), and DNA synthesis (1–5 µM). Arsenite stimulated p42/44 but not p38 MAPK phosphorylation (2.5 µM), responses different than those produced by epidermal growth factor. Inhibition of mitogen-activated protein kinase kinase (MAPKK) and p38 MAPK using PD98059 (20 µM) and SB202190 (5 µM), respectively, attenuated the elevation of COX-2 protein induced by arsenite, whereas physiological concentrations of three COX-2 inhibitors (e.g., NS-398, piroxicam, and aspirin) reduced arsenite-stimulated DNA synthesis. These data indicate that arsenite elevates COX-2 in NHEK at the transcriptional and translational levels as well as increases PGE2 secretion. Compounds that inhibit COX-2 expression and activity may be useful in the scientific study, prevention, and treatment of arsenic skin carcinogenesis and deserve further investigation.",
Arsenic,1508566,"Genome-wide alteration of histone H3K9 acetylation pattern in mouse offspring prenatally exposed to arsenic Abstract: Chronic exposure to arsenic in drinking water, especially in utero or perinatal exposure, can initiate neurological and cognitive dysfunction, as well as memory impairment. Several epidemiological studies have demonstrated cognitive and learning deficits in children with early exposure to low to moderate levels of arsenic, but pathogenic mechanisms or etiology for these deficits are poorly understood. Since in vivo studies show a role for histone acetylation in cognitive performance and memory formation, we examined if prenatal exposure to arsenic causes changes in the epigenomic landscape. We exposed C57Bl6/J mice to 100 ?g/L arsenic in the drinking water starting 1 week before conception till birth and applied chromatin immunoprecipitation followed by high-throughput massive parallel sequencing (ChIP-seq) to evaluate H3K9 acetylation pattern in the offspring of exposed and control mice. Arsenic exposure during embryonic life caused global hypo-acetylation at H3K9 and changes in functional annotation with highly significant representation of Krüppel associated box (KRAB) transcription factors in brain samples from exposed pups. We also found that arsenic exposure of adult mice impaired spatial and episodic memory, as well as fear conditioning performance. This is the first study to demonstrate: a) genome wide changes in H3K9 acetylation pattern in an offspring prenatally exposed to arsenic, and b) a connection between moderate arsenic exposure and cognitive impairment in adult mice. The results also emphasize the applicability of Next Generation Sequencing methodology in studies aiming to reveal the role of environmental factors, other than dietary restriction, in developmental reprogramming through histone modifications during embryonic development.",
Arsenic,2337228,"Food safety and bioavailability evaluations of four vegetables grown in the highly arsenic-contaminated soils on the Guandu Plain of northern Taiwan Abstract: Arsenic contamination in a large area of agricultural fields on the Guandu Plain of northern Taiwan was confirmed in a survey conducted in 2006, but research concerning the relationship between bioavailable As concentrations in contaminated soils and crop production in Taiwan is not available. Pot experiments were conducted to examine the growth and accumulation of As in four vegetable crops grown in As-contaminated soils and to assess As intake through consumption. The phytotoxic effects of As in soils were not shown in the pot experiments in which vegetable crops were grown in soils contaminated with different As levels in situ collected from Guandu Plain (120-460 mg/kg) or artificially spiked As-contaminated soils (50-170 mg/kg). Experimental results showed that the bioavailable As extracted with 0.5M NaHCO3 from soils can be used to estimate As concentrations in vegetables. The As concentrations in the vegetables were compared with data shown in the literature and As limits calculated from drinking water standards and the provisional tolerance weekly intake (PTWI) of inorganic As established by the Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO). Although the As levels in the vegetables were not high and the bioavailability of As in the soils was quite low, long-term consumption may result in higher As intake in the human body.",
Arsenic,1017160,"Arsenate exposure affects amino acids, mineral nutrient status and antioxidants in rice (Oryza sativa L.) genotypes Abstract: Simulated pot experiments were conducted on four rice (Oryza sativa L.) genotypes (Triguna, IR-36, PNR-519, and IET-4786) to examine the effects of As(V) on amino acids and mineral nutrient status in grain along with antioxidant response to arsenic exposure. Rice genotypes responded differentially to As(V) exposure in terms of amino acids and antioxidant profiles. Total amino acid content in grains of all rice genotypes was positively correlated with arsenic accumulation. While, most of the essential amino acids increased in all cultivars except IR-36, glutamic acid and glycine increased in IET-4786 and PNR-519. The level of nonprotein thiols (NPTs) and the activities of superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.6.4.2) and ascorbate peroxidase (APX; EC 1.11.1.11) increased in all rice cultivars except IET-4786. A significant genotypic variation was also observed in specific arsenic uptake (SAU; mg kg(-1)dw), which was in the order of Triguna (134) &gt; IR-36 (71) &gt; PNR-519 (53) &gt; IET-4786 (29). Further, application of As(V) at lower doses (4 and 8 mg L(-1) As) enhanced the accumulation of selenium (Se) and other nutrients (Fe, P, Zn, and S), however, higher dose (12 mg L(-1) As) limits the nutrient uptake in rice. In conclusion, low As accumulating genotype, IET-4786, which also had significantly induced level of essential amino acids, seems suitable for cultivation in moderately As contaminated soil and would be safe for human consumption.",
Arsenic,2343538,"Function of a deltaic silt deposit as a repository and long-term source of sulfate and related weathering products in a glaciofluvial aquifer derived from organic-rich shale (North Dakota, USA) Abstract: A shallow unconfined glaciofluvial aquifer in North Dakota (USA) has largest groundwater sulfate concentrations near the bottom boundary. A deltaic silt layer underlying the aquifer, at &gt; 16 m, is the modern proximate sulfate source for the aquifer. The original sulfate source was pyrite in the organic-rich shale component of the aquifer and silt grain matrix. An oxidizing event occurred during which grain-matrix pyrite sulfur was oxidized to sulfate. Thereafter the silt served as a ""conserving"" layer, slowly feeding sulfate into the lower part of the aquifer and the underlying till. A method was developed for estimating the approximate initial sulfate concentration in the source layer and the redistribution time since the oxidizing event, using a semi-generic convection-dispersion model. The convection-dispersion model and a model for the evolution of modern sulfate delta S-34 in silt-layer pore water from the initial grain-matrix pyrite delta S-34, both estimated that the oxidizing event occurred several thousand years ago, and was likely related to the dry conditions of the Hypsithermal Interval. The silt layer also serves as an arsenic source. Results indicate that deltaic silts derived from organic-rich shale parent materials in a glacial environment can provide long-term sources for sulfate and arsenic and possibly other related oxidative weathering products.",
Arsenic,1326998,"Activation of the Nrf2 pathway, but decreased gamma-glutamylcysteine synthetase heavy subunit chain levels and caspase-3-dependent apoptosis during exposure of primary mouse hepatocytes to diphenylarsinic acid Abstract: Diphenylarsinic acid (DPAsV) is a degradation product of chemical warfare agents, over which there has been a public outcry in the Kamisu Area of Ibaraki Prefecture in Japan. In this study, we investigated the cytotoxicity of and cellular response to DPAsV in primary mouse hepatocytes. Exposure of the hepatocytes to DPAsV resulted in cell damage accompanied by cellular accumulation of DPAsV in a time-dependent manner. The cell death caused by DPAsV was attributable to apoptosis. DPAsV activated a basic leucine-zipper transcription factor Nrf2 as determined by the nuclear translocation of Nrf2, anti-oxidant response element (ARE)-dependent luciferase activity, and upregulation of downstream gene products. However, gamma-glutamylcysteine synthetase heavy subunit chain (gamma-GCS(H)), which is regulated by Nrf2, underwent cleavage by activated caspase-3 to a 17 kDa fragment, leading to a minimal level of constitutive gamma-GCS(H) expression 72 h following the exposure (25 microM). Experiments with cycloheximide revealed that the DPAsV-mediated reduction in gamma-GCS(H) was due to a post-translational modification. The results suggest that DPAsV causes caspase-3-dependent cleavage of gamma-GCS(H) regardless of Nrf2 activation in primary mouse hepatocytes.",
Arsenic,1034077,"A rapid method for the selective analysis of total urinary metabolites of inorganic arsenic Abstract: Total urinary arsenic has traditionally been used for assessing occupational exposure to inorganic arsenic. However, dietary arsenic, especially from seafood, may greatly influence this value. This paper describes a fast and convenient method for routinely measuring the combined amount of inorganic arsenic, methylarsonic acid, and dimethylarsinic acid, which are the major urinary metabolites after exposure to inorganic arsenic. Organic arsenic compounds of marine origin are not biotransformed to inorganic arsenic or methylated arsenic acids to any significance in the human body. They do not produce arsines when treated with the reducing agent in the proposed method and will therefore not interfere with the measurements. The sensitivity, accuracy, and precision of the proposed method are sufficient for the determination of concentrations of arsenic normally found in the urine of nonexposed persons. The method is based on a commercially available hydride generation kit attached to an atomic absorption spectrophotometer.",
Arsenic,1033499,"Etiology of lung cancer at the Gejiu tin mine, China Abstract: There were 1,724 lung cancer cases registered at the Yunnan Tin Corporation in the period 1954-1986, of which 90% had a history of working underground. Previous exposure to radon, and radon daughters and arsenic is considered to be responsible for the high incidence of lung cancer in these miners. Arsenic may come from inhalation of arsenic-containing ore dust or other environmental arsenic pollution. It appears that radon exposure accounts to a greater extent than arsenic for the increase of lung cancer in these miners. Pathological study was made of 100 surgically resected lung cancer specimens. In this way the distribution and composition of dust retention was determined in relation to peripheral lung cancer.",
Arsenic,1797779,"Evaluation of dietary exposure to minerals, trace elements and heavy metals from the muscle tissue of the lionfish Pterois volitans (Linnaeus 1758) Abstract: Twenty-five samples of Pterois volitans caught in Jamaican waters were analysed for 25 essential, non-essential and toxic elements using Graphite Furnace Atomic Absorption Spectrophotometry (GF-AAS), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Instrumental Neutron Activation Analysis (INAA). The mean values for calcium (355 mg/kg), copper (107 ?g/kg), iron (0.81 mg/kg), potassium (3481 mg/kg), magnesium (322 mg/kg), manganese (0.04 mg/kg), selenium (0.47 mg/kg), sodium (700 mg/kg) and zinc (4.46 mg/kg) were used to estimate dietary intake. The percentage contribution to Provisional Tolerable Weekly Intake for a 70kg male and a 65kg female were also estimated for the toxic elements arsenic (4.53% M, 4.88% F), cadmium (0.43% M. 0.47% F), mercury (3.63% M, 3.91% F) and lead (2.00% M, 2.15% F). To further assess the risk of mercury toxicity and the role of mitigation provided by selenium, selenium mercury molar ratios were calculated for all samples. All samples were shown to have a molar excess of selenium. In addition the suggested selenium health benefit value was calculated, and was positive for all samples. It was concluded that Pterois volitans appears to contribute modestly to mineral and trace element nutrition, while not being a significant contributor to dietary exposure of toxic elements.",
Arsenic,130418,"Insights into the carcinogenic mode of action of arsenic Abstract: That arsenic can induce cancer in humans has been known since the late 17th century, yet how arsenic induces cancer has been the subject of numerous scientific publications. Various modes of action (MOA) have been proposed for arsenic's carcinogenicity. In this paper we review our previous studies on the ability of arsenicals to cause DNA damage, the relative inability of these arsenicals to induce point mutations, and the involvement of arsenicals in spindle disruption. We present new evidence that shows that reduced glutathione (GSH) can chemically reduce inactive pentavalent arsenicals to trivalent arsenicals which can disrupt tubulin polymerization, and show that reactive oxygen species (ROS) are most likely not involved in tubulin disruption. A hypothesis is also presented on how arsenic may induce stable chromosome aberrations (CAs) that can lead to cancer, thus supporting a role for genetic damage in the MOA for arsenic. We then propose promising areas of research that might give insight into the MOA of arsenic.",
Arsenic,2088547,"Probing the electronic structures and properties of neutral and charged arsenic sulfides (As n S ((-1,0,+1)), n?=?1-7) using Gaussian-3 theory Abstract: The structures and energies of neutral and charged arsenic sulfides As n S((-1,0,+1)) (n?=?1-7) were systematically investigated using the G3 method. The bonding properties and the stabilities of As n S and their ions were discussed. The adiabatic electron affinities (AEAs) and adiabatic ionization potentials (AIPs) were presented. The ground-state structures of As n S can be considered as the lowest-energy structure of neutral As n+1 by replacing an As atom with a S atom, that is, &quot;substitutional structure&quot;, in which the feature of sulfur bonding is edge-bridging. The ground-state structures of As n S(+) tend to be derived from the lowest-energy structure of cation As n (+) by attaching to a S atom, that is, &quot;attaching structure&quot;, in which the sulfur can be three-fold coordinated. There is no rule to be found for the ground-state structure of anion As n S(-), in which the sulfur can be a terminal atom. There are odd-even alternations in both AEAs and AIPs as a function of size of As n S. The dissociation energies of S, S(-), and/or S(+) from neutral As n S and their ions were calculated to examine their stabilities.",
Arsenic,1349856,Synthesis and voltammetric study of some new macrocyclic sulfur compounds for use as chelating agents for separation of arsenic (III) in wastewater and as molluscicidal agents against Biomophalaria Alexandrina Snails Abstract: ,
Arsenic,749355,"Heterogeneity of the DNA damage provoked by antimony and arsenic Abstract: Data on the mechanism of antimony genotoxicity is scarce. Arsenic and antimony are proposed to share some toxicological features. Thus comparative and combined experiments with As(III) and Sb(III) were performed to gain a deeper knowledge of the mechanism of antimony genotoxicity. Trivalent arsenic proved to be five times more cytotoxic and one order of magnitude more potent in induction of micronuclei in human lymphocytes in vitro than was antimony. Significantly increased micronucleus frequencies were achieved with As(III) at a dose of 0.5 microM and with Sb(III) at a dose of 5 microM. Neither the number of micronuclei induced by As(III) nor by Sb(III) could be suppressed by co-incubation with superoxide dismutase or catalase. This suggests that induction of oxidative stress may not be a crucial step in the mechanism of DNA damage induction by arsenic and antimony. The combined genotoxicity in micronucleus test co-incubation experiments with arsenic and antimony seemed best described by simple additivity. In the single cell gel test with human lymphocytes a significant induction of DNA damage was observed with 0.01 microM As(III) and 5 microM Sb(III). In contrast to Sb(III), As(III) proved to be a very potent inducer of DNA-protein crosslinks. It may be that Sb(III) as well as As(III) causes DNA damage by inhibition of enzymes involved in DNA repair. Further investigations will have to identify the relevant sites of action.",
Arsenic,627401,"Further studies on aberrant gene expression associated with arsenic-induced malignant transformation in rat liver TRL1215 cells Abstract: Chronic arsenic exposure of rat liver epithelial TRL1215 cells induced malignant transformation in a concentration-dependent manner. To further define the molecular events of these arsenic-transformed cells (termed CAsE cells), gene expressions associated with arsenic carcinogenesis or influenced by methylation were examined. Real-time RT-PCR showed that at carcinogenic concentrations (500 nM, and to a less extent 250 nM of arsenite), the expressions of alpha-fetoprotein (AFP), Wilm's tumor protein-1 (WT-1), c-jun, c-myc, H-ras, c-met and hepatocyte growth factor, heme oxygenase-1, superoxide dismutase-1, glutathione-S-transferase-pi and metallothionein-1 (MT) were increased between 3 to 12-fold, while expressions of insulin-like growth factor II (IGF-II) and fibroblast growth factor receptor (FGFR1) were essentially abolished. These changes were not significant at the non-carcinogenic concentration (125 nM), except for IGF-II. The positive cell-cycle regulators cyclin D1 and PCNA were overexpressed in CAsE cells, while the negative regulators p21 and p16 were suppressed. Western-blot confirmed increases in AFP, WT-1, cyclin D1 and decreases in p16 and p21 protein in CAsE cells. The CAsE cells over-expressed MT but the demethylating agent 5-aza-deoxycytidine (5-aza-dC, 2.5 microM, 72 h) stimulated further MT expression. 5-Aza-deoxycytidine restored the loss of expression of p21 in CAsE cells to control levels, but did not restore the expression of p16, IGF-II, or FGFR1, indicating the loss of expression of these genes is due to factors other than DNA methylation changes. Overall, an intricate variety of gene expression changes occur in arsenic-induced malignant transformation of liver cells including oncogene activation and alterations in expression of genes critical to growth regulation.",
Arsenic,628735,"Urinary porphyrins as biomarkers for arsenic exposure among susceptible populations in Guizhou province, China Abstract: Coal is widely used in PR China. Unfortunately, coal from some areas in Guizhou Province contains elevated levels of arsenic. This has caused arsenicosis in individuals who use arsenic-contaminated coal for the purposes of heating, cooking and drying of food in poorly ventilated dwellings. The population at risk has been estimated to be approximately 200,000 people. Clinical symptoms of arsenicosis may include changes of skin pigmentation, hyperkeratosis of hand and feet, skin cancers, liver damage, persistent cough and chronic bronchitis. We analyzed the porphyrin excretion profile using a HPLC method in urine samples collected from 113 villagers who lived in Xing Ren district, a coal-borne arsenicosis endemic area and from 30 villagers from Xing Yi where arsenicosis is not prevalent. Urinary porphyrins were higher in the arsenic exposed group than those in the control group. The correlation between urinary arsenic and porphyrin concentrations demonstrated the effect of arsenic on heme biosynthesis resulting in increased porphyrin excretion. Both uroporphyrin and coproporphyrin III showed significant increases in the excretion profile of the younger age (<20 years) arsenic-exposed group, suggesting that porphyrins could be used as early warning biomarkers of chronic arsenic exposure in humans. Greater increases of urinary arsenic and porphyrins in women, children and older age groups who spend much of their time indoors suggest that they might be at a higher risk. Whether elevated porphyrins could predict adverse health effects associated with both cancer and non-cancer end-points in chronically arsenic-exposed populations need further investigation.",
Arsenic,1019610,"Lung cancer and arsenic exposure in drinking water: A case-control study in northern Chile Abstract: In some Chilean cities, levels of arsenic (As) in drinking water reached 800 (micrograms/L between 1950 and 1970, while current levels are 40 (micrograms/L. To evaluate the causal role of this exposure in lung and bladder cancers, we conducted a case-control study in Regions I, II, and III of the country. From 1994 to 1996, cases diagnosed as lung cancer and two hospital controls were entered in the study; one control was a patient with a cancer, while the other was a patient without cancer, both conditions unrelated to As. Controls were matched with cases by age and sex. A standard survey containing questions about residence, employment, health history, was administered to study subjects. Data on As concentrations in water were obtained from records of the municipal water companies. A total of 151 lung cancer cases and 419 controls (167 with cancer and 242 without cancer) were enrolled. Median level of lifetime As exposure was significantly higher among cases, with a clear dose-response relationship between mean As exposure levels, with an OR (95% CI) of: 1, 1.7 (0.5-5.1), 3.9 (1.2-13.4), 5.5 (2.2-13.5), and 9.0 (3.6-22) for strata one to five respectively. This study provides new evidence that As in drinking water can cause internal cancers and gives an estimate of the form of this relationship.",
Arsenic,1031980,"Role of thiols in the in-vitro methylation of inorganic arsenic by rat liver cytosol Abstract: Rat liver cytosol inactivates inorganic arsenic (Asi) through methylation; S-adenosylmethionine is the methyl group donor and reduced glutathione (GSH) is required for full activity. The study of the combined effects of Asi, GSH and other thiols in vitro and the results of our previous in-vivo studies in humans and rats are consistent with a pathway involving the formation of a monomethylated metabolite which is either rapidly further methylated into a dimethylated derivative or is spontaneously oxidized into monomethylarsonic acid (MMA). The dimethylated metabolite gives rise to dimethylarsinic acid. The first methylation reaction is rate limiting, can be stimulated by GSH and is catalyzed by an enzyme different from that which transfers the second methyl group. The latter is sensitive to inhibition by inorganic arsenic. The stimulation of the first methylation reaction by GSH can only be evidenced at high Asi concentration because under these conditions, the second methylating enzyme can be sufficiently inhibited by Asi to allow some accumulation of MMA. The latter may also slow down the first methylation reaction. A large excess of thiol groups may prevent the methylation reactions probably by decreasing the amount of free trivalent arsenic.",
Arsenic,1508717,"Arsenic contamination in the freshwater fish ponds of Pearl river delta: Bioaccumulation and health risk assessment Abstract: This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05-3.01 mg?kg(-1) wet weight (w. wt) and 8.41-22.76 mg?kg(-1) dry weight (d. wt), respectively. In addition, the As content was positively correlated (p?&lt;?0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and ? (15)N. The slope of the regression (-0.066 and -0.078) of the log transformed As concentrations and ? (15)N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10(-4)) stipulated by the USEPA.",
Arsenic,628586,"Oxidative activation of the human carcinogen chromate by arsenite: A model for synergistic metal activation leading to oxidative DNA damage Abstract: Human exposure to toxic metals and metalloids in the environment seldom occurs from a single pure compound. Most environmental exposure profiles are heterogeneous with co-exposure occurring coincident with multiple toxic metal species. This co-exposure to metals and metalloids in complex mixtures can result in a synergistic, additive or even depletive toxic response. The complexity of interactions presented by metal mixtures presents a need for convenient and sensitive methods to determine potential toxic responses from such co-exposure. We have studied the reaction between the two commonly associated toxic metals of chromate, Cr(VI), and arsenite, As(III), with regards to the ability of As(III) to reductively activate Cr(VI) to generate oxidative stress and DNA damage. Using a DCF-based fluorescent dye assay we have demonstrated that the redox reaction between As(III) and Cr(VI) yields high valent intermediates of chromium, Cr(V), that are highly oxidizing. This induction of oxidizing potential was dose dependent and did not occur with As(III) or Cr(VI) alone or, with the other major oxidation state of arsenic, arsenate, As(V). The mechanism of oxidation of DCFH to the fluorescent species, DCF, in this reaction was through a direct, metal-based oxidation since addition of radical scavengers did not significantly decrease oxidation of the dye in this system. The addition of a ligand that stabilizes the high valent Cr(V) oxidation state, 2-ethyl-2-hydroxybutyric acid (EHBA), to the chromate and arsenite mixture resulted in an enhancement of DCF fluorescence. The DCF fluorescence observed with the Cr(VI) and As(III) mixture was also found to correlate with oxidative DNA damage as measured by a plasmid nicking assay. These data show how metal-metal interactions in environmental mixtures could result in the synergistic induction of oxidative stress and DNA damage. Further, these data demonstrate the utility of the DCF fluorescence assay as a sensitive method for screening synergistic redox interactions in metal mixtures.",
Arsenic,1019095,"Relationships between quantitative measures and neurologist's clinical rating of tremor and standing steadiness in two epidemiological studies Abstract: <strong>OBJECTIVE: </strong>The purpose of the present investigation was to 1) compare a neurologist's physical examination (NPx) rating of severity of postural tremor to several summary measures derived from quantitative measurements of tremor and 2) compare a NPx rating of standing steadiness and related clinical findings to quantitative sway speed measurements.<br /><br /><strong>METHODS: </strong>Comparisons were performed on data obtained from two epidemiological field studies: 1) retired heavy industrial workers (n= 198, approximately half previously exposed to elemental mercury), and 2) small town residents (n=234, approximately 40% with environmental exposure to arsenic). A commercially available tremor measurement instrument was used in both studies. To obtain standing steadiness measures, a head position monitoring device was used in the mercury study, and a force platform was used in the arsenic study. The NPx included assessment of postural tremor, as well as evaluation of vibration perception and proprioception of the great toe, Achilles tendon reflex activity, Romberg test status, and tandem gait. One neurologist performed all the NPx in both studies and results were graded as normal, equivocal, or abnormal. The square root of the proportion of variance accounted for by a linear trend term in ANOVA models was used as an estimate of association between quantitative tests and clinical examination grade. An estimate of agreement, kappa, was also calculated after both NPx and quantitative test results were dichotomized.<br /><br /><strong>RESULTS: </strong>Most tremor summary measures varied monotonically with NPx tremor severity grade. Moderately good associations were observed between the tremor acceleration measure and NPx postural tremor grade (correlations up to approximately 0.5). Sway speed with eyes open and with eyes closed increased monotonically with NPx grade for most of the clinical signs. The NPx signs showing the strongest relationships with sway speed were Romberg test performance, tandem gait, and proprioception and vibration sensation of the great toe (correlations up to approximately 0.5).<br /><br /><strong>CONCLUSIONS: </strong>Quantitative tremor measurements were related to a neurologist's grading of postural tremor. Sway speed was associated with several NPx findings related to standing stability. Quantitative measurements of tremor and standing stability may provide more precise and objective measures of neurological function than NPx by a neurologist and are likely to be more consistent across times and examiners.",
Arsenic,2345659,"Electrochemical Stimulation of Microbial Roxarsone Degradation under Anaerobic Conditions Abstract: Roxarsone (4-hydroxy-3-nitrophenylarsonic acid) has been commonly used in animal feed as an organoarsenic additive, most of which is excreted in manure. Roxarsone is easily biodegraded to 4-hydroxy-3-aminophenylarsonic acid (HAPA) under anaerobic conditions, but HAPA persists for long periods in the environment, increasing the risk of arsenic contamination through diffusion. We investigated the electrochemical stimulation of the microbial degradation of roxarsone under anaerobic conditions. After the carbon sources in the substrate were depleted, HAPA was slowly degraded to form arsenite under anaerobic conditions. The degradation rate of HAPA was significantly increased when 0.5 V was applied without adding a carbon source. The two-cell membrane reactor assays reveal that the HAPA was degraded in the anode chambers, confirming that the anode enhanced the electron transfer process by acting as an electron acceptor. The degradation product formed with electrochemical stimulation was arsenate, which facilitates the removal of arsenic from wastewater. Based on the high performance liquid chromatography-ultraviolet-hydride generation-atomic fluorescence spectrometry (HPLC-UV-HG-AFS) and gas chromatography-mass spectrometry (GC-MS) data, the pathway for the biodegradation of roxarsone and the mechanisms for the electrochemically stimulated degradation are proposed. This method provides a potential solution for the removal of arsenic from organoarsenic-contaminated wastewater.",
Arsenic,2278416,"Sandy beaches contamination by arsenic, a result of nearshore sediment diagenesis and transport (Brazilian coastline) Abstract: We studied the distribution of As, Fe, Ca and Al in beach sands and near-shore surface sediments along the Brazilian coast from the equatorial zone to Rio de Janeiro state. High concentrations of As (up to 120 mg kg(-1)) exceeding the environmentally acceptable thresholds were found in the beach sands and near-shore surface sediment in several segments of the studied coast. That increased from north to south. The significant positive correlation (R-2 = 0.58) between As and calcium carbonate in the beach sands corroborated the hypothesis that calcareous bioclasts participate in metalloid retention and its accumulation in beach sediments. Most likely, enrichment of As occurs in the oxic horizon of sediments caused by the diagenetic redistribution of various elements. Enrichment of As in beach sands occurs in the coast of Bahia and Espirito Santo states. That is facilitated by clastic material of calcareous algae. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,2278646,"Arsenate resistant Penicillium coffeae: A potential fungus for soil bioremediation Abstract: Bioremediation is an effective method for the treatment of major metal contaminated sites. Fungi were isolated from soil samples collected from different arsenate contaminated areas across India. An isolate, Penicillium coffeae, exhibited resistance to arsenate up to 500 mM. Results indicated that pretreatment of biomass with alkali (NaOH) enhanced the percentage of adsorption to 66.8 % as compared to that of live and untreated dead biomass whose adsorption was 22.9 % and 60.2 % respectively. The physiological parameters evaluated in this study may help pilot studies aimed at bioremediation of arsenate contaminated effluents using arsenate resistant fungus P. coffeae.",
Arsenic,628026,"Arsenic-induced micronuclei formation in mammalian cells and its counteraction by tea Abstract: The Gangetic plain of West Bengal, India, has been engulfed by a disastrous environmental calamity of arsenic contamination of the ground water. Chronic arsenic toxicity caused by drinking arsenic-contaminated water has been one of the worst health hazards gradually affecting nine districts of West Bengal since the early 1980s. Over and above hyperpigmentation and keratosis,weakness, burning sensation of the eyes, swelling of the legs, liver fibrosis, chronic lung disease, gangrene of the toes, neuropathy, and skin cancer are other manifestations. Induction of cancer is frequently associated with DNA damage, changes in ploidy of cells, and non-random chromosome aberrations. Counteraction of these genotoxic and cytogenetic abnormalities with natural dietary polyphenols could be a useful strategy to combat arsenic-induced DNA damage and thereby cancer. A review of the literature showed that it is the antioxidant property of tea polyphenols that affords protection against various types of cancer. The present study was conducted to investigate whether the extracts of green tea and black tea (Darjeeling and Assam) as well as their polyphenols could ameliorate this arsenic-induced genotoxicity. The normal mammalian cell culture derived from male Chinese hamster lung fibroblast cells (V79) was used as the test system to assess the genotoxicity by micronucleus assay. The results showed that both green tea and black tea extracts have equal potential in modulating the arsenic-induced genotoxicity. This effect was perhaps induced by the constituent polyphenols present in green and black tea. In addition, the repair activity of the damaged cells was enhanced when treated with these tea extracts and their polyphenols. Thus, tea and its polyphenols may have a promising role in counteracting the devastating effects of arsenic.",
Arsenic,1386023,"Cancer incidence and mortality among Swedish Baltic Sea fishermen Abstract: BIOSIS COPYRIGHT: BIOL ABS. A 25% lower cancer mortality was found for 1360 Swedish fishermen who fished on the Baltic Sea than for the general population. The fishermen consumed twice as much fish as the population in the same county. In spite of the low overall cancer mortality, increased mortality from myeloma, as well as increased incidences of gastric carcinoma and squamous cell cancer of the skin and lips, was observed in the cohort. The decrease in risk for ischemic heart disease was not significant. Whether the dietary intake of fatty acids and selenium from fish contributed to the decreased risk was difficult to evaluate. Moreover, whether the consumption of fish from the Baltic Sea, contaminated with, for example, polychlorinated dioxins and dibenzofurans and other persistent organochlorine substances, contributed to the observed increase specific cancer risks is not known. However, the net health effects of high fish consumption from the Baltic Sea seems to be positive.",
Arsenic,1017993,"Contrasting influence of geology on E. coli and arsenic in aquifers of Bangladesh Abstract: Arsenic in groundwater has been a concern in South and Southeast Asia for more than a decade. We explore here the possibility that hydrogeologic factors recently shown to influence the distribution of arsenic might also affect the level of contamination of shallow (&lt;20 m) wells with microbial pathogens. A total of 96 shallow tube wells in two nearby villages of Bangladesh were surveyed during the wet and dry seasons, along with 55 deeper wells in neighboring villages. One of the two villages is located in a particularly sandy environment where recharge is rapid and shallow wells contain little arsenic. Shallow aquifers in the other village are capped with an impermeable clay layer, recharge is an order of magnitude slower, and arsenic levels are high. The fecal indicator E. coli was detected in 43% of shallow wells, compared with 12% of deeper wells. More shallow wells contained E. coli during the wet season (61%) than during the dry season (9%). In the wet season, a higher proportion of shallow wells in the village with low arsenic levels (72%) contained E. coli compared with the village having high arsenic levels (43%). Differences in arsenic and E. coli distributions between the two sites are likely due to the differences in permeability of near-surface sediments although differences in average well-depth between the two villages (9 ± 4 vs. 15 ± 3 m) may play a role as well. Hydrogeologic conditions that favor high levels of fecal contamination but low levels of arsenic in shallow groundwater should be taken into account during arsenic mitigation throughout South and Southeast Asia.",
Arsenic,2343439,"Phosphorous and sulfur nutrition modulate antioxidant defenses in Myracrodruom urundeuva plants exposed to arsenic Abstract: We investigated if plant nutrition and antioxidant system activation are correlated features of arsenic (As)-tolerance in Myracrodruom urundeuva. Plants were grown for 120 days in substrates with 0, 10, 50 and 100mg Askg(-1) and its As-tolerance was demonstrated. As-concentrations greater than 10mgkg(-1) decreased plant growth and photosynthesis but did not induce plant death. Plants coupled alterations in stomatal conductance and transpiration to avoid As-deleterious effects to the photosynthetic apparatus. As-toxicity in M. urundeuva was due to lipid peroxidation induced by hydrogen peroxide accumulation. Ascorbate peroxidase (APX) and gluthatione peroxidase (GPX) had central roles in hydrogen peroxide (H2O2) scavenging in leaves, and their activities were linked to changes in redox potentials (ascorbate and glutathione pools). APX and GPX inactivation/degeneration led to H2O2 accumulation and related lipid peroxidation. Increased phosphorus (P) and sulfur (S) concentrations in leaves were related to increased APX and GPX activities by stimulating increases in glutathione biosynthesis. We concluded that P and S nutrition were directly linked to As-tolerance in M. urundeuva plants by increasing antioxidant system activities.",
Arsenic,647103,"Kidney cancer mortality: Fifty-year latency patterns related to arsenic exposure Abstract: BACKGROUND: Arsenic in drinking water is associated with kidney cancer. Beginning in 1958, a region of Chile experienced a rapid onset of high arsenic exposure in drinking water, followed by sharp declines when water treatment plants were installed in 1971. METHODS: For the years 1950-1970, we obtained mortality data from death certificates for an exposed region and an unexposed region in Chile. We obtained computerized mortality data for all of Chile for 1971-2000. RESULTS: Kidney cancer risks for the exposed region compared with the unexposed started to increase about 10 years after high arsenic exposures began in 1958. The peak kidney cancer mortality rate ratio (RR) was 3.4 (95% confidence interval = 2.2-5.1) for men in 1981-1985, with subsequent declines to 1.6 (1.2-2.1) by 1996-2000. Mortality RRs among women were 2.9 (1.8-4.7) in 1981-1985 but remained high longer than for men, increasing further to a RR of 4.4 (3.0-6.4) in 1991-1995. Early-life exposure resulted in an increased RR of 7.1 (3.1-14) for young adults aged 30-39 years, born just before or during the high exposure period. CONCLUSIONS: This study shows a latency pattern of increased mortality from kidney cancer, continuing for at least 25 years after the high exposures began to decline. Early life exposure resulted in markedly higher kidney cancer mortality in young adults.",
Arsenic,2345668,"Economic Feasibility Study for Improving Drinking Water Quality: A Case Study of Arsenic Contamination in Rural Argentina Abstract: Economic studies are essential in evaluating the potential external investment support and/or internal tariffs available to improve drinking water quality. Cost-benefit analysis (CBA) is a useful tool to assess the economic feasibility of such interventions, i.e. to take some form of action to improve the drinking water quality. CBA should involve the market and non-market effects associated with the intervention. An economic framework was proposed in this study, which estimated the health avoided costs and the environmental benefits for the net present value of reducing the pollutant concentrations in drinking water. We conducted an empirical application to assess the economic feasibility of removing arsenic from water in a rural area of Argentina. Four small-scale methods were evaluated in our study. The results indicated that the inclusion of non-market benefits was integral to supporting investment projects. In addition, the application of the proposed framework will provide water authorities with more complete information for the decision-making process.",
Arsenic,1509324,Assessing metal bioaccumulation from estuarine sediments: Comparative experimental results for the polychaete Arenicola marina Abstract: ,
Arsenic,710823,"Arsenic in drinking water and stroke hospitalizations in Michigan Abstract: Mechanistic and human studies suggest a role for arsenic in ischemic stroke; however, risks from chronic, low-level exposures are uncertain and US studies are lacking. The objective was to investigate the association between low-level arsenic exposure in drinking water and ischemic stroke hospital admissions in Michigan.<br /><br /> Ischemic stroke hospital admissions among those aged ? 45 years were identified (1994 to 2006). Population-weighted average arsenic concentrations were estimated for each Michigan county (n = 83) and for zip codes in Genesee County (n=27) where there is greater variation in arsenic concentrations. US Census data provided age- and sex-specific population counts and other county- and zip code-level variables (race, income), which were adjusted for in multilevel negative binomial regression models of arsenic and stroke admissions. Hospital admissions for duodenal ulcer and hernia, not hypothesized to be associated with arsenic, were also evaluated.<br /><br /> Adjusted county-level analyses suggested a relationship between arsenic and ischemic stroke hospital admissions, although similar associations were observed for duodenal ulcer and hernia. In zip code-level analysis, arsenic was associated with an increased risk of stroke admission (relative risk, 1.03; 95% CI, 1.01 to 1.05 per ?g/L increase in arsenic) after adjustment for confounders, and null or negative associations were found between arsenic and nonvascular outcomes.<br /><br /> Findings from this study suggest that exposure to even low levels of arsenic in drinking water may be associated with a higher risk of incident stroke. Given the ecological nature of the analysis, further epidemiological study with individual-level data on arsenic exposure and incident stroke is warranted.",
Arsenic,2343428,"Arsenic mobilization in aquifers of the southwest Songnen basin, P.R. China: Evidences from chemical and isotopic characteristics Abstract: High As groundwater has widely been found in the inland basins of China. Little is known about distribution and mobilization mechanisms of high As groundwater in the Songnen basin, where groundwater is the major source for drinking and irrigation. Eighty-seven groundwater samples, three surface water samples and sixty-three sediment samples were taken from the southwest of the Songnen basin, in order to investigate spatial distribution and constrains of groundwater As. Results showed that high As groundwater was generally of Na-Mg/Ca-HCO3 type, which had relatively low Eh values and neutral-weakly alkaline pH. High As groundwater was characterized by low concentrations of NO3(-) and SO4(2-), and high concentrations of Fe, Mn, and H2S. Around 65.5% of sampled shallow groundwater and 96% of sampled deep groundwater had As concentrations greater than 10?g/L. Sediments had higher total As contents and higher Fe/Mn oxide-bound As contents in high As groundwater area than in the low As groundwater area. Distribution of groundwater As was dependent upon hydrogeologic settings, redox potential, microbial degradation of organic carbon, and precipitation of pyrite, siderite, and calcite. Along the groundwater flow path, As concentration showed an increasing trend. High As groundwater was mainly distributed in the low-lying areas. Reducing conditions were the major causes for As mobilization in the aquifers, which led to more As released from the sediments with higher contents of Fe/Mn oxide-bound As in higher As groundwater area. Results of (13)CDOC and (13)CDIC showed that dissimilatory Fe(III) reduction coupled with microbial degradation of dissolved organic carbon would be related to As mobilization in the aquifers. Although both Fe and As were released during these redox processes, pyrite, siderite and calcite precipitation would be the sink of dissolved As, which resulted in weak correlation between dissolved Fe and As.",
Arsenic,80847,"Arsenic induces overexpression of growth factors in human keratinocytes Abstract: Although epidemiological studies have shown that inorganic arsenicals are human skin carcinogens and induce hyperproliferation and hyperkeratosis, there is currently no known mechanism for their action or an established animal model for its study. We observed increased mRNA transcripts and secretion of keratinocyte growth factors, including granulocyte macrophage-colony stimulating factor (GM-CSF) and transforming growth factor-alpha (TGF alpha) and the proinflammatory cytokine tumor necrosis factor-alpha in primary human epidermal keratinocytes cultured in the presence of low micromolar concentrations of sodium arsenite. Treatment with sodium arsenite resulted in a significant increase in cell proliferation, as indicated by increases in cell numbers, c-myc gene expression, and incorporation of [3H]thymidine into cellular DNA. Studies of transcriptional regulation indicate that the rate of GM-CSF mRNA transcription is increased, while the elevated TGF alpha is likely the results of message stabilization. While a number of cytokine regulatory networks exist in the skin, studies utilizing neutralizing antibodies against the growth factors of interest indicate that inhibition of the arsenic-induced increase in TGF alpha results in a corresponding decrease in the gene expression and secretion of GM-CSF. The present studies demonstrate that growth-promoting cytokines and growth factors are induced in keratinocytes following treatment with arsenic and could play a significant role in arsenic-induced skin cancer.",
Arsenic,67668,"A pilot study on the urinary excretion of porphyrins in human populations chronically exposed to arsenic in Mexico Abstract: 1 The aim of this pilot study was to investigate if the porphyrinuria produced by arsenic in rodents was present in humans chronically exposed to arsenic via drinking water. 2 The concentrations of uroporphyrin, coproporphyrin and total arsenic in urine were compared between 21 individuals exposed to arsenic in their drinking water (0.390 mg l-1) and 19 controls exposed to 0.012 mg l-1. 3 Arsenic-exposed individuals had significantly higher total arsenic concentrations in their urine than the control group. No increase in urinary porphyrin excretion was found in exposed individuals. However, an inversion of the coproporphyrin/uroporphyrin (COPRO/URO) ratio was observed in most exposed individuals. This inversion was caused both, by a decrease in coproporphyrin excretion and an increase in uroporphyrin excretion. 4 No demonstrable correlations between porphyrin excretion, the COPRO/URO ratio and total arsenic concentration in urine were found in exposed individuals.",
Arsenic,1337273,"Stress granules inhibit apoptosis by reducing ROS production Abstract: Cells can undergo two alternative fates following exposure to environmental stress; they either induce apoptosis, or inhibit apoptosis and then repair the stress-induced alterations. These processes minimize cell loss and prevent the survival of cells with aberrant DNA and protein alterations. These two alternative fates are partly controlled by stress granules (SGs). While arsenite, hypoxia and heat shock induce the formation of SGs that inhibit apoptosis, X-ray irradiation and genotoxic drugs do not induce SGs, and they are more prone to trigger apoptosis. However, it is unclear precisely how SGs control apoptosis. This study found that SGs suppress the elevation of reactive oxygen species (ROS), and this suppression is essential to inhibit ROS-dependent apoptosis. This antioxidant activity of SGs is controlled by two SG components, G3BP1 and USP10. G3BP1 elevates the steady-state ROS level by inhibiting the antioxidant activity of USP10. However, following exposure to arsenite, G3BP1 and USP10 induce the formation of SGs, which uncovers the antioxidant activity of USP10. We also found that the antioxidant activity of USP10 requires the protein kinase activity of ataxia telangiectasia mutated (ATM). This work reveals that SGs are critical redox regulators that control the cell fate under stress conditions.",
Arsenic,2337237,"ERGO: A pilot study of ketogenic diet in recurrent glioblastoma Abstract: Limiting dietary carbohydrates inhibits glioma growth in preclinical models. Therefore, the ERGO trial (NCT00575146) examined feasibility of a ketogenic diet in 20 patients with recurrent glioblastoma. Patients were put on a low-carbohydrate, ketogenic diet containing plant oils. Feasibility was the primary endpoint, secondary endpoints included the percentage of patients reaching urinary ketosis, progression-free survival (PFS) and overall survival. The effects of a ketogenic diet alone or in combination with bevacizumab was also explored in an orthotopic U87MG glioblastoma model in nude mice. Three patients (15%) discontinued the diet for poor tolerability. No serious adverse events attributed to the diet were observed. Urine ketosis was achieved at least once in 12 of 13 (92%) evaluable patients. One patient achieved a minor response and two patients had stable disease after 6 weeks. Median PFS of all patients was 5 (range, 3-13) weeks, median survival from enrollment was 32 weeks. The trial allowed to continue the diet beyond progression. Six of 7 (86%) patients treated with bevacizumab and diet experienced an objective response, and median PFS on bevacizumab was 20.1 (range, 12-124) weeks, for a PFS at 6 months of 43%. In the mouse glioma model, ketogenic diet alone had no effect on median survival, but increased that of bevacizumab-treated mice from 52 to 58 days (p&lt;0.05). In conclusion, a ketogenic diet is feasible and safe but probably has no significant clinical activity when used as single agent in recurrent glioma. Further clinical trials are necessary to clarify whether calorie restriction or the combination with other therapeutic modalities, such as radiotherapy or anti-angiogenic treatments, could enhance the efficacy of the ketogenic diet.",
Arsenic,1332237,"A proteolytic activity enhanced by arsenite in Chinese hamster ovary cells: possible involvement in arsenite-induced cell killing Abstract: Treatment of Chinese hamster ovary (CHO-K1) cells with 10 microM sodium arsenite for 24 h resulted in enhancement of a proteolytic activity toward the chromogenic substrate CBZ-Phe-Arg-AMC. Presence of dithiothreitol and a pH between 4 and 6 were required for displaying its full hydrolytic activity. According to its substrate- and inhibitor-specificity, this arsenite-induced proteolytic activity was very similar to lysosomal cathepsin B. Arsenite cytotoxicity was further shown to be partially prevented by inhibitors that inhibited the arsenite-induced protease, such as antipain and chymostatin, but not by protease inhibitors without inhibitory effects on the arsenite-induced protease. Our present results suggest that the arsenite-induced protease activity may be involved in arsenite's killing effects.",
Arsenic,710884,"Chronic arsenic exposure impairs macrophage functions in the exposed individuals Abstract: Owing to the established roles of human macrophages in immune defense, we investigated the effect of chronic arsenic exposure upon these major hematopoietic cells in 70 arsenic-exposed individuals with skin lesions and 64 unexposed individuals.<br /><br /> Human monocyte-derived macrophages were prepared from peripheral blood mononuclear cells, by culture of the adherent cells for 6 days in medium supplemented with granulocyte-monocyte colony stimulating factor. Parameters studied included cell adhesion capacity, expression of CD54 and F-actin, nitric oxide production, phagocytic capacity, and effect of arsenic on Rho A-ROCK pathway.<br /><br /> In macrophages of exposed individuals when compared to unexposed group, there was cell rounding accompanied with a significant (p &lt; 0.001) loss of cell adhesion capacity, decrease in nitric oxide production, impaired phagocytic capacity, and decreased CD 54 and F-actin expression. Additionally, chronic arsenic exposure affected Rho A-ROCK pathway which in turn impaired macrophage functions.<br /><br /> These altogether could contribute significantly to arsenic-induced immunosuppression observed in the arsenic-exposed individuals.",
Arsenic,1337311,"Draft Genome Sequence of a Novel Bacterial Strain, LSJC7, Belonging to the Family Enterobacteriaceae with Dual Resistance to Arsenic and Tetracycline Abstract: Strain LSJC7, with dual resistance to arsenic and tetracycline, was isolated from an antimony tailing in China. Its 16S rRNA gene sequence has the highest similarity to that of Enterobacter cloacae subsp. dissolvens LMG 2683(T) (97.02%). Here we present the approximately 4.6-Mbp draft genome sequence of strain LSJC7.",
Arsenic,1056062,"Characterization of particulate matter (PM10) related to surface coal mining operations in Appalachia Abstract: This study investigates the environmental exposure of residents of a community in southwest Virginia to respirable concentrations of dust (PM-10 i.e. PM10) generated by trucks hauling coal from surface coal mining operations. The study site is representative of communities in southwest Virginia and other parts of Appalachia that are located in narrow hollows where homes are placed directly along roads that experience heavy coal truck traffic.Preliminary air sampling (Particulate Matter i.e. PM10) was conducted for a period of approximately two weeks during early August 2008 in the unincorporated community of Roda, Virginia, at two locations (about a mile apart along Roda Road (Route 685) in Wise County, Virginia). For the purposes of this study (a combination of logistics, resource, and characterization of PM) we sited the PM samplers near the road to ascertain the micro exposure from the road. The results revealed high levels of PM10 (the mean adjusted 24-h concentration at the Campbell Site=250.2 mu gm-3 ( plus or minus 135.0 mu gm-3); and at the Willis Site=144.8 plus or minus 60.0 mu gm-3). The U.S. 24-h national ambient air quality standard for PM10 is 150 mu gm-3. Elemental analysis for samples (blank-corrected) collected on Quartz filter paper (on one randomly selected day) at both the sites revealed the presence of antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, selenium. Electron micrographs reveal the morphology and habit (shapes and aggregates) of the particulate matter collected.",
Arsenic,1579334,"Alkaline decomposition of synthetic jarosite with arsenic Abstract: The widespread use of jarosite-type compounds to eliminate impurities in the hydrometallurgical industry is due to their capability to incorporate several elements into their structures. Some of these elements are of environmental importance (Pb2+, Cr6+, As5+, Cd2+, Hg2+). For the present paper, AsO43- was incorporated into the lattice of synthetic jarosite in order to carry out a reactivity study. Alkaline decomposition is characterized by removal of sulfate and potassium ions from the lattice and formation of a gel consisting of iron hydroxides with absorbed arsenate. Decomposition curves show an induction period followed by a conversion period. The induction period is independent of particle size and exponentially decreases with temperature. The conversion period is characterized by formation of a hydroxide halo that surrounds an unreacted jarosite core. During the conversion period in NaOH media for [OH-] &gt; 8 x 10-3 mol L-1, the process showed a reaction order of 1.86, and an apparent activation energy of 60.3 kJ mol-1 was obtained. On the other hand, during the conversion period in Ca(OH)2 media for [OH-] &gt; 1.90 x 10-2 mol L-1, the reaction order was 1.15, and an apparent activation energy of 74.4 kJ mol-1 was obtained. The results are consistent with the spherical particle model with decreasing core and chemical control.",
Arsenic,2278807,"Environmental occurrence of arsenic in Colombia: A review Abstract: The international literature on the presence of arsenic (As) in Latin America does not disclose the true magnitude of the presence of As in Colombia. In this paper, we summarize the literature on As occurrence in Colombia. The data reveal that As is present in matrices such as soil, sediments and water and in the food chain. Some of the As concentrations exceed the limits specified by national and international regulations. Arsenic higher concentrations are associated with mining regions (e.g., soils, up to 148 mg/kg; sediments, up to 1400 mg/kg) and agricultural areas (e.g., vegetables, up to 5.40 mg/kg; irrigation water, up to 255 ?g/L), and underscore the potential human and environmental risks associated with the presence of As in the country. This review highlights the importance of focusing research on understanding the occurrence, origin and distribution of As in Colombia to better understand its environmental and public health impact.",
Arsenic,1597424,"Efficient removal of trace arsenite through oxidation and adsorption by magnetic nanoparticles modified with Fe-Mn binary oxide Abstract: Magnetic nanoparticles (MNPs) modified simultaneously with amorphous Fe and Mn oxides (Mag-Fe-Mn) were synthesized to remove arsenite [As(III)] from water. Mag-Fe-Mn particles were fabricated through heterogeneous nucleation technique by employing the maghemite as the magnetic core and Fe-Mn binary oxide (FMBO) as the coating materials. Powder X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy were utilized to characterize the hybrid material. With a saturation magnetization of 23.2 emu/g, Mag-Fe-Mn particles with size of 20-50 nm could be easily separated from solutions with a simple magnetic process in short time (within 5 min). At pH 7.0, 200 ?g/L of As(III) could be easily decreased to below 10 ?g/L by Mag-Fe-Mn particles (0.1 g/L) within 20 min. As(III) could be effectively removed by Mag-Fe-Mn particles at initial pH range from 4 to 8 and the residual As was completely oxidized to less toxic arsenate [As(V)]. The co-occurring redox reactions between Mn oxide and As(III) was confirmed by XPS analysis. Chloride, sulfate, bicarbonate, and nitrate at common concentration range had negligible influence on As(III) removal, whereas, silicate and phosphate reduced the As(III) removal by competing with arsenic species for adsorption sites. As(III) removal was not obviously affected by natural organic matter (up to 8 mg/L as TOC). Mag-Fe-Mn could be regenerated with ternary solution of NaOH, NaCl, and NaClO. Throughout five consecutive cycles, the adsorption and desorption efficiencies maintained above 98% and 87%, respectively. Mag-Fe-Mn had a larger adsorption capacity for As(III) (47.76 mg/g) and could remove trace As(III) more thoroughly than MNPs modified solely with either Fe or Mn oxide due to the synergistic effect of the coating Fe and Mn oxides. This research extended the potential applicability of FMBO to a great extent and provided a convenient approach to efficiently remove trace As(III) from water.",
Arsenic,1340158,"Novel miRNAs in the control of arsenite levels in rice Abstract: In a species, the miRNA repertoire comprises many lineage- or species-specific miRNAs. Using deep sequencing, the whole transcriptome of seedling roots was studied and a total of 18 novel miRNAs in indica rice Minghui 86 were identified. Among these novel miRNAs six were up-regulated and two were down-regulated under arsenite stress. Quantitative real-time RT-PCR analysis revealed that miR6254 was predominantly expressed in roots relative to other tissues, whereas miR6250 and miR169i-3p were constitutively expressed in all tissues examined, with high abundance in roots (miR6250) or leaves (miR169i-3p). The miR6250 and miR169i-3p miRNAs also exhibited distinct expression patterns in rice cultivars Minghui 86 and Nipponbare at different time points after arsenite treatment. The predicted targets for these miRNAs included some protein kinases, DNA, or ATP-binding proteins. Besides arsenite, the expression of targets of miR6250 and miR6254 was also up- or down-regulated in response to abiotic environmental stresses, indicative of their involvement in regulation of plant adaptation. Three types of cis-elements involved in hormone, light, and stress response were found to occur frequently in the promoter regions. Interestingly, miR6254 was originally characterized to be an exonic miRNA located in the exon of AK101391, supporting the notion that miRNAs may also originate from some exons in plants.",
Arsenic,2345705,"Ultralight Mesoporous Magnetic Frameworks by Interfacial Assembly of Prussian Blue Nanocubes Abstract: A facile approach for the synthesis of ultralight iron oxide hierarchical structures with tailorable macro-and mesoporosity is reported. This method entails the growth of porous Prussian blue (PB) single crystals on the surface of a polyurethane sponge, followed by in situ thermal conversion of PB crystals into three-dimensional mesoporous iron oxide (3DMI) architectures. Compared to previously reported ultralight materials, the 3DMI architectures possess hierarchical macro-and mesoporous frameworks with multiple advantageous features, including high surface area (ca. 117 m(2) g(-1)) and ultralow density (6-11 mg cm(-3)). Furthermore, they can be synthesized on a kilogram scale. More importantly, these 3DMI structures exhibit superparamagnetism and tunable hydrophilicity/hydrophobicity, thus allowing for efficient multiphase interfacial adsorption and fast multiphase catalysis.",
Arsenic,1508642,"The inhibition of HIF-2? on the ATM/Chk-2 pathway is involved in the promotion effect of arsenite on benzo(a)pyrene-induced cell transformation Abstract: Both arsenite and benzo(a)pyrene (BaP) are known human carcinogens. Studies on the mode-of-action of arsenite indicate that it can also act as co-carcinogen or as a cancer promoter, and that it can facilitate progression of cancers. Some studies on development of lung cancers have suggested a synergism between arsenite exposure and cigarette smoking. The mechanism of action for such an effect, however, remains obscure. In the present study, we investigated the effects of HIF-2? on arsenite- and BaP-induced cell malignant transformation as well as on signal transduction pathways in human bronchial epithelial (HBE) cells. The results show that arsenite accelerates the neoplastic transformation and migration of cells and enhances chromosomal aberrations induced by BaP. HIF-2? is involved in blocking the effects of arsenite in activating the ATM/Chk-2 pathway and in repair of DNA damage induced by BaP. Moreover, blocking of HIF-2? prevents the effects of arsenite on the neoplastic transformation, cell migration, and chromosomal aberrations caused by BaP. These results indicate that the repressive effect of HIF-2? on the ATM/Chk-2 pathway leads to genomic instability, which is involved in arsenite-accelerated, BaP-induced malignant transformation of HBE cells.",
Arsenic,1030102,"A mortality study of Danish stokers Abstract: This study was set up to investigate whether work as a stoker is associated with an increased risk of specific malignant neoplasms. For this purpose, a cohort of 2777 male stokers was followed up through a 10 year period with regard to cause specific mortality. Comparisons were made with another cohort of unskilled male workers in physically demanding jobs. The mortality of the stokers was significantly increased for lung cancer (standardised mortality ratio (SMR) 145, 95% confidence interval (95% CI) 110-186) and for multiple myeloma (SMR 388, 95% CI 106-994). Also, increases were seen for cancer of the urinary organs and cancer of the mouth and throat. The combustion products to which the stokers have been exposed comprise several carcinogenic agents including polycyclic aromatic hydrocarbons, benzene, arsenic, and radionuclides. It seems likely that the occupational exposure of stokers has contributed to their excess cancer mortality.",
Arsenic,2345645,"Higher urinary heavy metal, phthalate, and arsenic but not parabens concentrations in people with high blood pressure, U.S. NHANES, 2011-2012 Abstract: Link between environmental chemicals and human health has emerged but not been completely examined in risk factors. Therefore, it was aimed to study the relationships of different sets of urinary environmental chemical concentrations and risk of high blood pressure (BP) in a national, population-based study. Data were retrieved from United States National Health and Nutrition Examination Surveys, 2011-2012 including demographics, BP readings, and urinary environmental chemical concentrations. Analyses included chi-square test, t-test and survey-weighted logistic regression modeling. After full adjustment (adjusting for urinary creatinine, age, sex, ethnicity, and body mass index), urinary cesium (OR 1.56, 95%CI 1.11-2.20, P = 0.014), molybden (OR 1.46, 95%CI 1.06-2.01, P = 0.023), manganese (OR 1.42, 95%CI 1.09-1.86, P = 0.012), lead (OR 1.58, 95%CI 1.28-1.96, P < 0.001), tin (OR 1.44, 95%CI 1.25-1.66, P < 0.001), antimony (OR 1.39, 95%CI 1.10-1.77, P = 0.010), and tungsten (OR 1.49, 95%CI 1.25-1.77, P < 0.001) concentrations were observed to be associated with high BP. People with higher urinary mono-2-ethyl-5-carboxypentyl phthalate (OR 1.33, 95%CI 1.00-1.62, P = 0.006), mono-n-butyl phthalate (OR 1.35, 95%CI 1.13-1.62, P = 0.002), mono-2-ethyl-5-hydroxyhexyl (OR 1.25, 95%CI 1.05-1.49, P = 0.014), mono-n-methyl phthalate (OR 1.26, 95%CI 1.07-1.48, P = 0.007), mono-2-ethyl-5-oxohexyl (OR 1.25, 95%CI 1.07-1.48, P = 0.009), and monobenzyl phthalate (OR 1.40, 95%CI 1.15-1.69, P = 0.002) tended to have high BP as well. However, there are no clear associations between environmental parabens and high BP, nor between pesticides and high BP. In addition, trimethylarsine oxide (OR 2.47, 95%CI 1.27-4.81, P = 0.011) and dimethylarsonic acid concentrations (OR 1.42, 95%CI 1.12-1.79, P = 0.006) were seen to be associated with high BP. In sum, urinary heavy metal, phthalate, and arsenic concentrations were associated with high BP, although the causal effect cannot be established from the current study design. Elimination of environmental chemicals in humans would still need to be continued.",
Arsenic,4872,"Use of job-exposure matrix in an occupational analysis of lung and bladder cancers on the basis of death certificates Abstract: A job-exposure matrix has been applied in a case-control study of lung and bladder cancer on the basis of occupational information abstracted from British death certificates. The expected association between lung cancer and jobs entailing exposure to asbestos was clearly demonstrated (relative risk, 1.5; 95% confidence interval, 1.2-1.9). The effects of three other known industrial carcinogens were not apparent, and reasons for this were discussed. Also included in the matrix were five substances whose carcinogenicity in humans has not been established. Formaldehyde, diesel fumes, and cutting oils were all associated with carcinoma of the bronchus, but the absence of a risk in ""high-exposure"" occupations was against a causal relationship. Bladder cancer was more common in jobs involving high exposure to printing inks (relative risk, 5.0; 95% confidence interval, 1.0-25.8) and cutting oils (relative risk, 1.5; 95% confidence interval, 0.8-2.8). Use of the job-exposure matrix added considerably to the conventional analysis of cancer risk in individual occupational categories.",
Arsenic,450282,"Knowledge of arsenic in drinking-water: Risks and avoidance in Matlab, Bangladesh Abstract: Widespread contamination of arsenic in Bangladesh has been jeopardizing the health of millions of people. Residents of Matlab, Bangladesh, are among the millions at risk. Using bivariate models in the analysis of survey data, knowledge of health risks and avoidance of arsenic exposure in response to widespread contamination of arsenic for residents of Matlab were estimated. The models examined individuals' knowledge of an arsenic problem in the household and knowledge of specific illnesses caused by arsenic exposure. The likelihood of avoiding exposure to arsenic contamination was further examined. Results of the estimation showed that individual's knowledge of arsenic problems in the household was gathered through awareness campaigns and by word of mouth and that knowledge of illnesses was predicated on education, health, presence of children, elderly and young women. Adoption of avoidance measures was not affected by exposure to arsenic-information sources, but level of education had a statistically significant positive effect on the decision to avoid arsenic exposure. Lack of convenience of safe drinking-water practices lead people to persist in drinking arsenic-contaminated water.",
Arsenic,1308741,"Oxygen tension regulates heme oxygenase-1 gene expression in mammalian cell lines Abstract: The gene expression of heme oxygenase-1 (HO-1) was studied in mammalian cell lines exposed to hyperoxia. Northern blot analysis demonstrated that hyperoxic exposure increased the HO-1 mRNA levels in various types of cells, including human hepatoma (HepG2) cells. This increase was time- and dose-dependent, and reversible. The HO-1 mRNA levels in HepG2 cells were increased to 2.3- and 4.2-fold of the control by hyperoxic exposure of 6 and 23 h, respectively. Cycloheximide and actinomycin D inhibited the increases in the HO-1 mRNA level produced by hyperoxia, indicating that response to hyperoxia is dependent on de novo protein synthesis and mRNA transcription. Antioxidants, desferrioxamine (DES) and o-phenanthroline (OP) partially inhibited the HO-1 mRNA elevation by hyperoxia. In addition to hyperoxia, sodium arsenite (NaAsO2), cadmium chloride (CdCl(2)) and hydrogen peroxide (H2O2), which are reactive oxygen intermediates (ROI) generators, increased the HO-1 mRNA level by 11-, 22- and 2.5-fold, respectively. OP, an antioxidant and a bivalent metal chelator, blocked the HO-1 mRNA elevation induced either by hyperoxia or by the three ROI generators. In contrast to OP, N-acetylcysteine (NAC), an antioxidant and membrane-permeable reducing reagent, enhanced the HO-1 mRNA elevation induced by hyperoxia, although NAC inhibited the mRNA elevation induced by NaAsO2, CdCl2 and H2O2. These results indicate that oxygen tension regulates HO-1 gene expression and suggest that hyperoxia-specific and redox-sensitive regulators may be involved in hyperoxia-mediated HO-1 gene expression.",
Arsenic,1355767,"Arsenic dose in patients with cutaneous carcinomata and hepatic haemangio-endothelioma after environmental and occupational exposure Abstract: A total of 16 male cases with malignant tumours associated with arsenic-polluted water were observed in Tarapacá and Antofagasta Provinces, northern Chile. Fifteen of them had skin carcinomata and the remaining one a haemangio-endothelioma of liver. The 15 skin cancer cases had latent periods ranging from 12–45 years. Three patients were studied in detail. The first one (skin cancer) had a latent period of 20 years with a weighted mean dose of 1.2 mg/day (total dose for latent period 8.4 g). The second one (skin cancer) had a latent period of 23 years with a weighted mean dose of 1.0 mg/day (total dose for latent period 8.3 g). The third case (liver tumour) exhibited a latent period of 14 years with a weighted mean of 0.6 mg/day (total dose for latent period 3.1 g). Fifteen of the 16 cancer patients were labourers. For normal subjects of different ages and both sexes (n=290) and ingesting arsenic-polluted water (0.60 ppm), the relationship between mean age and mean arsenic dose is expressed by a weighted least square polynomial regression, of second degree: ?(y) = ?o + ?1 t + ?2 t 2 where y is mean arsenic dose (mg/person/day) and t is mean age (years). For the general male population and for male labourers, the respective equations are presented.",
Arsenic,2149292,"Exogenous nitric oxide (as sodium nitroprusside) ameliorates arsenic-induced oxidative stress in watercress (Nasturtium officinale R. Br.) plants Abstract: This research investigated the effects of exogenous sodium nitroprusside (SNP) supplementation as a nitric oxide (NO) on alleviating arsenic-induced oxidative damage in watercress (Nasturtium officinale R. Br.) plants. In arsenic-treated plants, dry weight of roots and shoots and chlorophyll content of leaves markedly decreased, while application of 100 mu M SNP, alleviated the inhibitory effect of arsenic on plant growth and chlorophyll content in arsenic-treated plants. Treatment with 100 mu M SNP considerably reduced root-to-shoot translocation of arsenic and increased slightly the protein and praline content in watercress tissues. Level of oxidative markers (lipoxygenase activity and malondialdehyde (MDA) and H2O2 content) sharply increased in arsenic-treated plants. Upon application of SNP this trend was alleviated; however, the activities of enzymatic antioxidants increased when plants were subjected to arsenic stress in combination with SNP. Results obtained in the present study suggest that exogenous NO could alleviate negative effects of arsenic on watercress plants probably through its ability to the stimulation of reactive oxygen species (ROS)-scavenging enzymes activity and/or direct scavenging of superoxide onion. (c) 2013 Elsevier B.V. All rights reserved.",
Arsenic,406467,Demographic and Behavioral Modifiers of Arsenic Exposure Pathways: A Bayesian Hierarchical Analysis of NHEXAS Data Abstract: A Bayesian analysis of the NHEXAS data provides subpopulation-specific pathways of arsenic exposure.,
Arsenic,2345806,"Multi-elements atmospheric deposition study in Albania Abstract: For the first time, the moss biomonitoring technique and inductively coupled plasma-atomic emission spectrometric (ICP-AES) analytical technique were applied to study multi-element atmospheric deposition in Albania. Moss samples (Hypnum cupressiforme) were collected during the summer of 2011 and September-October 2010 from 62 sites, evenly distributed over the country. Sampling was performed in accordance with the LRTAP Convention-ICP Vegetation protocol and sampling strategy of the European Programme on Biomonitoring of Heavy Metal Atmospheric Deposition. ICP-AES analysis made it possible to determine concentrations of 19 elements including key toxic metals such as Pb, Cd, As, and Cu. Cluster and factor analysis with varimax rotation was applied to distinguish elements mainly of anthropogenic origin from those predominantly originating from natural sources. Geographical distribution maps of the elements over the sampled territory were constructed using GIS technology. The median values of the elements in moss samples of Albania were high for Al, Cr, Ni, Fe, and V and low for Cd, Cu, and Zn compared to other European countries, but generally were of a similar level as some of the neighboring countries such as Bulgaria, Croatia, Kosovo, Macedonia, and Romania. This study was conducted in the framework of ICP Vegetation in order to provide a reliable assessment of air quality throughout Albania and to produce information needed for better identification of contamination sources and improving the potential for assessing environmental and health risks in Albania, associated with toxic metals.",
Arsenic,1597422,Degradation characteristics of the major PML isoforms in response to arsenic Abstract: ,
Arsenic,1337593,"Arsenic Control During Aquifer Storage Recovery Cycle Tests in the Floridan Aquifer Abstract: Implementation of aquifer storage recovery (ASR) for water resource management in Florida is impeded by arsenic mobilization. Arsenic, released by pyrite oxidation during the recharge phase, sometimes results in groundwater concentrations that exceed the 10 µg/L criterion defined in the Safe Drinking Water Act. ASR was proposed as a major storage component for the Comprehensive Everglades Restoration Plan (CERP), in which excess surface water is stored during the wet season, and then distributed during the dry season for ecosystem restoration. To evaluate ASR system performance for CERP goals, three cycle tests were conducted, with extensive water-quality monitoring in the Upper Floridan Aquifer (UFA) at the Kissimmee River ASR (KRASR) pilot system. During each cycle test, redox evolution from sub-oxic to sulfate-reducing conditions occurs in the UFA storage zone, as indicated by decreasing Fe(2+) /H(2) S mass ratios. Arsenic, released by pyrite oxidation during recharge, is sequestered during storage and recovery by co-precipitation with iron sulfide. Mineral saturation indices indicate that amorphous iron oxide (a sorption surface for arsenic) is stable only during oxic and sub-oxic conditions of the recharge phase, but iron sulfide (which co-precipitates arsenic) is stable during the sulfate-reducing conditions of the storage and recovery phases. Resultant arsenic concentrations in recovered water are below the 10 µg/L regulatory criterion during cycle tests 2 and 3. The arsenic sequestration process is appropriate for other ASR systems that recharge treated surface water into a sulfate-reducing aquifer.",
Arsenic,2279070,"Arsenate-Ferrihydrite Systems from Minutes to Months: A Macroscopic and IR Spectroscopic Study of an Elusive Equilibrium Abstract: Sorption by ferrihydrite is an important control on As(V) concentrations in many oxic aquatic systems. There are significant discrepancies in reported sorption constants (log(KAs)), which presents a problem for quantifying and understanding this important system. A review of reported ferrihydrite-As(V) sorption studies indicated a positive correlation between reaction time used in the experiments and the log(KAs) values derived from the data. In this paper, we study the kinetics of As(V) sorption over ?3000 h in nine systems with varying pH and As(V)/Fe. Ferrihydrite was stable in all systems containing As(V), and the [As(V)] in solution decreased linearly as a function of log(t) (termed Elovich kinetics) over the full 3000 h in most systems. A stable [As(V)] was only observed in systems with low As(V)/Fe and low pH. Apparent As(V) sorption constants were derived from the data at specific time intervals using the diffuse layer model and equations describing log(KAs) values as a function of time provide a way to describe this elusive equilibrium. IR spectra support the hypothesis that slow interparticle diffusion is responsible for the slow approach to equilibrium. This work resolves discrepancies in previous studies of As(V)-ferrihydrite and provides equations to allow for system appropriate log(KAs) values to be used.",
Arsenic,1519081,"Atriplex atacamensis and Atriplex halimus resist As contamination in Pre-Andean soils (northern Chile) Abstract: The Pre-Andean area of Chile exhibits saline soils of volcanic origin naturally contaminated with arsenic (As), and we hypothesise that revegetation with resistant species may be a valid alternative for soil management in this area. Thus, the xerophytic and halophytic shrubs Atriplex halimus and Atriplex atacamensis were cultivated in containers for 90days in Pre-Andean soil, As-soil, (111±19mgAskg(-1), pH8.4±0.1) or control soil (12.7±1.1mgAskg(-1), pH7.8±0.1) to evaluate As accumulation and resistance using stress bioindicators (chlorophylls, malondialdehyde (MDA) and total thiols). Sequential extraction of As-soil indicated that 52.3% of As was found in the most available fraction. The As distribution was significantly different between the species: A. halimus translocated the As to leaves, whilst A. atacamensis retained the As in roots. At 30 and 90days, A. halimus showed similar As concentrations in the leaves (approximately 5.5mgAskg(-1)), and As increased in stems and roots (up to 4.73 and 16.3mgAskg(-1), respectively). In A. atacamensis, As concentration was lower (2.6 in leaves; 3.2 in stems and 6.9 in roots in mgAskg(-1)). Both species exhibited a high concentration of B in leaves (362-389mgkg(-1)). If the plants are used for animal feed, it should be considered that A. halimus accumulates higher concentration of As and B in the leaves than A. atacamensis. Neither plant growth nor stress bioindicators were negatively affected by the high levels of available As, with the exception of MDA in the leaves of A. halimus. The results indicate that these plants resist contamination by arsenic, accumulating mainly the metalloid in the roots and can be recommended to generate plant cover in As-contaminated soils in the Pre-Andean region, under saline conditions controlled, preventing the dispersion of this metalloid via wind and leaching.",
Arsenic,1579398,"A study of the temporal dynamics of ambient particulate matter using stochastic and chaotic techniques Abstract: Temporal dynamics of particulate matter (PM) concentration are affected by a variety of complex physical and chemical interactions among ambient pollutants and various exogenous factors (e.g. meteorological variables). Consequently, the dynamics of PM concentration can be considered either as a stochastic process or as a deterministic process. Many studies have applied stochastic and chaotic approaches independently to study the dynamics of PM concentration. However, none of them has compared these two complementary approaches for verification and possible confirmation of the outcomes. The present study makes an attempt to address this issue, through application of the dynamic factor analysis (DFA) (a stochastic method) and the correlation dimension (CD) method (a chaotic method) to study the temporal dynamics of ambient pollutants. More specifically, these two methods are employed to identify the number of variables dominantly governing the dynamics of PM concentration, with analysis of PM10, PM2.5, and ten other variables observed at the Hsing-Chuang station in Taipei (Taiwan). The results from the two methods are found to be consistent, with the DFA method suggesting eight common trends among the observed time series and the CD method suggesting eight variables dominantly governing the dynamics of both PM10 and PM2.5. This study provides an excellent example for the utility of both stochastic and chaotic approaches in modeling atmospheric and environmental systems, as these approaches not only shed light in their own ways but also complement each other in capturing the salient characteristics of such systems, especially from the perspective of simplified modeling. (C) 2012 Elsevier Ltd. All rights reserved.",
Arsenic,1025530,"Metastasis-induction and apoptosis-protection by TWIST in gastric cancer cells Abstract: TWIST, a basic helix-loop-helix transcription factor, has been recently reported to play an important role in tumorigenesis of human cancer through converting the early stage tumors into invasive malignancies. Upregulation of TWIST is often found in cancer patients, especially those with shorter survival period and poor response to chemotherapy. Here we studied the functions of TWIST on regulating migration rate, apoptosis, and gene expression in gastric cancer cells. TWIST expression is elevated in MGC-803 and HGC-27 cells that exhibit high invasive potential; whereas it is reduced in BGC-823 and SGC-7901 cells that possess relatively low invasive content. To evaluate functional consequences of TWIST induction, we examined the effect of TWIST on cell migration and apoptosis. Overexpression of TWIST in BGC-823 cells resulted in increased migration content and decreased sensitivity to the arsenic oxide-induced cell death. Moreover, small interference RNA-mediated TWIST ablation in MGC-803 and HGC-27 cells showed suppressed migration ability, increased induction of apoptosis in response to arsenic oxide, and elevated cell cycle arrest. Furthermore, we found a negative correlation between the TWIST level and p53 level, probably due to transcriptional regulation. Our results have identified TWIST as a critical regulator of gastric cancer cell proliferation and migration, suggesting a potential therapeutic approach to inhibit the growth and metastasis of gastric cancer through inactivation of TWIST.",
Arsenic,627173,"Arsenic: Signal transduction, transcription factor, and biotransformation involved in cellular response and toxicity Abstract: Arsenic is a naturally occurring metalloid that causes oxidative stress. Exposure of humans, experimental animals, and cultured cells to arsenic results in a variety of diverse health effects, dysfunction of critical enzymes, and cell damage. In this context, one area of arsenic study has been the role of its metabolism. Like organic chemicals, arsenic undergoes reduction, methylation, and glutathione conjugation to yield polar metabolites that are substrates for transporters. These events suggest that transcription factor(s) controlling the upregulation of antioxidant proteins, Phase II xenobiotic-metabolizing enzymes, and Phase III transporters should affect arsenic-mediated oxidative stress and the steady-state level of arsenic in the cells. In this review, we summarize recent progress in arsenic toxicity in terms of disrupted signal transduction cascades, the transcription factors involved, and arsenic biotransformation, including a novel pathway.",
Arsenic,1026562,"Arsenic salt-induced DNA damage and expression of mutant p53 and COX-2 proteins in SV-40 immortalized human uroepithelial cells Abstract: Arsenic is widely distributed in the environment, and is a proven toxic and carcinogenic agent that is associated with various human malignancies, including bladder cancer. However, the mechanisms of its carcinogenic action are still not well understood. In addition, over-expression of mutant p53 and cyclooxygenase-2 (COX-2) frequently occurs in a variety of human malignancies. It is therefore of interest to study the genotoxicity of arsenic salts on human uroepithelial cells and the expression of oncoproteins p53 and COX-2. In this study, the relative genotoxicity of sodium arsenite was evaluated in SV-40 immortalized human uroepithelial cells (SV-HUC-1) using the alkaline comet assay. The expression of mutant p53 and COX-2 was also evaluated by immunocytochemistry and western blotting. Our results revealed that sodium arsenite was able to induce DNA damage, and that its genotoxicity is correlated with its concentration. In addition, the expression of mutant p53 increased in parallel with comet scores, and the maximal expression of mutant p53 was observed at 4 microM arsenite. Similarly, sodium arsenite stimulated a concentration-dependent increase in COX-2 expression. In conclusion, this study demonstrated that sodium arsenite is genotoxic to uroepithelial cells in vitro, and that it will induce expression of mutant p53 and COX-2 proteins, indicating a possible key event in carcinogenesis. This study provides us with knowledge of the relationship between p53 and COX-2 over-expression in arsenite-treated urothelial cells and suggests a potential therapeutic role of COX-2 inhibitors in human urothelial malignancies.",
Arsenic,710964,"Inorganic arsenic as a developmental toxicant: in utero exposure and alterations in the developing rat lungs Abstract: In the present study, we characterize the toxic effects of in utero arsenic exposure on the developing lung. We hypothesize that in utero exposure to inorganic arsenic through maternal drinking water causes altered gene and protein expression in the developing lung, indicative of downstream molecular and functional changes. From conception to embryonic day 18, we exposed pregnant Sprague-Dawley rats to 500 ppb arsenic (as arsenite) via the drinking water. Subtracted cDNA libraries comparing control to arsenic exposed embryonic lungs were generated. In addition, a broad Western blot analysis was performed to identify altered protein expression. A total of 59 genes and 34 proteins were identified as being altered. Pathway mapping and analysis showed that cell motility was the process most affected. The most likely affected pathway was alteration in integrin signaling through the beta-catenin pathway, altering c-myc. The present study shows that arsenic induces alterations in the developing lung. These data may be useful in the elucidation of molecular targets and biomarkers of arsenic exposure during lung development and may aid in understanding the etiology of arsenic induced adult respiratory disease and lung cancers.",
Arsenic,1032965,"Characterization of lewisite toxicity in isolated perfused skin Abstract: Lewisite (L) is a potent organic arsenical that causes rapid onset of pain and severe vesication on contact with epithelial tissues. The isolated perfused porcine skin flap (IPPSF) is an in vitro model that has shown potential as a model for cutaneous vesicant research. The objective of this study was to characterize IPPSF responses after topical exposure to six concentrations of L ranging from 0.07 to 5.0 mg/ml (n = 4/treatment plus controls). Biochemical markers of viability (glucose utilization (CGU) and lactate dehydrogenase (LDH) release), vascular resistance (VR), venous arsenic flux, and morphological parameters (light and electron microscopy) were evaluated. In addition, lewisite lesions were characterized at 1, 3, 5, and 8 hr after exposure (n = 4/time plus controls) using these morphological parameters, as well as enzyme histochemistry. Macroscopic and microscopic lesions caused by L exposure were dose related. Mild decreases in CGU were noted with the higher concentrations of L, while generally increased responses in LDH release and VR were seen. Marked increases in LDH activity were noted in the blister fluid of IPPSFs treated with 5.0 mg/ml of L. Also, significant cutaneous arsenic flux was noted at the 5.0 mg/ml dose of L. The formation of gross blisters, the location and characterization of epidermal-dermal junction separation, and the time course of lesion production paralleled the description of L-induced lesions in humans. The sensitivity of the IPPSF to L exposure and the similarity of lesions to those described for humans suggests that this model provides a relevant in vitro model with which to study mechanisms of chemical vesication and arsenic toxicity, as well as protective and therapeutic intervention for vesicant exposure.",
Arsenic,460437,"A comparison of elementary schoolchildren's exposure to arsenic and lead Abstract: One hundred fifty seven fifth-grade students (aged 10-12 years) from three elementary schools in three different towns in Taichung County, Taiwan were chosen as study subjects for the present arsenic and lead exposure study. The three townsLonggang, Shalach, and Shuntainare known to be highly, moderately, and lightly (control) polluted by As and Pb, respectively. Spot morning urine samples of students were collected and analyzed for arsenic and lead. The levels of As in the urine of Longgang schoolchildren showed the highest value among the three schools, while those of the control group (Shuntain) had the lowest values. In addition, the levels of Pb in the urine of the schoolchildren in Shuntain were significantly lower than those in Longgang and Shalach, while the levels of Pb in the urine of the schoolchildren in Longgang and Shalach showed no significant difference. Results of daily intake of metals from the different exposure pathways (i.e., ingestion from drinking water, household dust and food, and inhalation from airborne particles) showed that the Longgang area had the highest daily intake of As and Pb among the three areas, while the lowest daily intake of As and Pb occurred in the control area (Shuntain). A significant correlation between the doses of daily intake and urinary concentrations of As (p = 0.002) and Pb (p = 0.020) was observed. This correlation suggests that the increase of unit dose of the daily intake for As resulted in an increase of 0.953 mu g g(-1) creatinine of As, whereas the increase of unit dose of the daily intake for Pb led to an increase of 0.053 mu g g(-1) creatinine of Pb. These data indicate that the level of As in urine increased about 18 times higher than that of Pb for the same amount of increase in daily intake.",
Arsenic,1027621,"Arsenic increased lipid peroxidation in rat tissues by a mechanism independent of glutathione levels Abstract: The role of lipid peroxidation in the mechanism of arsenic toxicity was investigated in female rats pretreated with N-acetylcysteine (NAC, a glutathione [GSH] inducer) or with buthionine sulfoximine (BSO, a GSH depletor). Rats were challenged with sodium arsenite, and sacrificed 1 hr after this treatment. Results showed that arsenic decreased GSH levels and increased lipid peroxidation in liver, kidney, and heart, with a larger effect at 18.2 mg/kg than at 14.8 mg/kg for lipid peroxidation induction. In the liver of rats treated with arsenic, pretreatment with NAC increased the levels of GSH and decreased lipid peroxidation. In kidney and heart, NAC pretreatment protected the tissues against arsenic-induced depletion of GSH levels, but the same degree of protection was not found for lipid peroxidation induction. In its turn, BSO had an additive effect with arsenic in lowering the levels of GSH in the liver and kidney, but an inverse correlation between GSH levels and lipid peroxidation was found only in liver. Arsenic content in tissues of rats pretreated with NAC was lower than in rats treated only with arsenic. In rats with depleted levels of GSH (BSO-pretreated rats), a shift in arsenic tissue distribution was found, with higher levels in skin and lower levels in kidney. A clear tendency for a positive correlation between arsenic concentration and lipid peroxidation levels was found in liver, kidney, and heart.",
Arsenic,2088485,"Cancer control in Bangladesh Abstract: Cancer is predicted to be an increasingly important cause of morbidity and mortality in Bangladesh in the next few decades. The estimated incidence of 12.7 million new cancer cases will rise to 21.4 million by 2030. More than two-thirds of the total expenditure on health is through out-of-pocket payments. According to the Bangladesh Bureau of Statistics, cancer is the sixth leading cause of death. International Agency for Research on Cancer has estimated cancer-related death rates in Bangladesh to be 7.5% in 2005 and 13% in 2030. The two leading causes are in males are lung and oral cancer and in females are breast cancer and cervical cancer. Bangladesh is now in severe shortage of radiation therapy machines, hospital bed, trained oncologists, medical radiation physicists and technologists. Bangladesh having different cancers associated with smoking and smokeless tobacco use, Human papilloma virus infection, Hepatitis B and C infection, Helicobacter Pylori infection, arsenic contaminated groundwater, availability of chemical carcinogens mainly formalin treated fruits, fish and vegetables at open market, tannery waste contaminated with chromium (which is used for poultry feed and fish feed preparation). A World Health Organization study revealed the annual cost of illnesses in Bangladesh attributable to tobacco usage is US$ 500 million and the total annual benefit from the tobacco sector is US$ 305 million as tax revenue. Bangladesh has developed a National Cancer Control Strategy and Action Plan with the aim of delivering a universal, quality-based and timely service. Cancer prevention through tobacco control, health promotion and vaccination program, cancer early detection program for oral cavity, breast and cervix has initiated. Cancer detection and diagnostic facilities will be made available at medical colleges and district- hospitals and establish a referral chain. National capacity development, more cancer research will allow Bangladesh to deal effectively and efficiently with the cancer problems through evidence-based decision making.",
Arsenic,1340100,"Chemical mixtures in untreated water from public-supply wells in the U.S.--occurrence, composition, and potential toxicity Abstract: Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources.",
Arsenic,1017514,"Small-scale and household methods to remove arsenic from water for drinking purposes in Latin America Abstract: Small-scale and household low-cost technologies to provide water free of arsenic for drinking purposes, suitable for isolated rural and periurban areas not connected to water networks in Latin America are described. Some of them are merely adaptation of conventional technologies already used at large and medium scale, but others are environmentally friendly emerging procedures that use local materials and resources of the affected zone. The technologies require simple and low-cost equipment that can be easily handled and maintained by the local population. The methods are based on the following processes: combination of coagulation/flocculation with adsorption, adsorption with geological and other low-cost natural materials, electrochemical technologies, biological methods including phytoremediation, use of zerovalent iron and photochemical processes. Examples of relevant research studies and developments in the region are given. In some cases, processes have been tested only at the laboratory level and there is not enough information about the costs. However, it is considered that the presented technologies constitute potential alternatives for arsenic removal in isolated rural and periurban localities of Latin America. Generation, handling and adequate disposal of residues should be taken into account in all cases.",
Arsenic,1357501,"Morbidity among municipal waste incinerator workers Abstract: Incinerator workers are exposed to many toxic compounds, most notably heavy metals. We evaluated medical and exposure monitoring data of an actively employed cohort of Philadelphia incinerator workers following an Agency for Toxic Substances and Disease Registry site survey and National Institute for Occupational Safety and Health (NIOSH) health hazard evaluation (HHE). Of the many airborne samples taken by NIOSH, only four of the personal breathing zone samples were above OSHA or ACGIH standards: one for lead, one for phosphorous, and two for total particulates. Because samples were taken during limited operations (only one of the two incinerators were operating), the results may underestimate historical exposures at this site. We limited our medical analysis to the 86 male workers who participated in the HHE out of the 105 active employees. The 86 employees were divided into potential high and low exposure groups based on a work site analysis done by an independent industrial hygienist. Eight individuals had at least one elevated biological index indicating exposure to a heavy metal. These elevations, however, were unrelated to the workers' exposure categories. Furthermore, no clinically significant mean blood or serum measurements were noted. Thirty-four percent of the workers had evidence of hypertension which increased the risk of significant proteinuria. Neither hypertension nor proteinuria were related to exposure group. Changes in pulmonary function related only to smoking status. Although there was some evidence of an increased risk of exposure to products of incinerator waste, we could not relate the few elevated biological tests to exposure classification. Additional studies are needed to assess the potential health effects of municipal waste incinerator by-products.",
Arsenic,1353357,"Synthesis and crystal structure of a solvate of arsenic 4,6-dimethyl-8-quinolinethiolate Abstract: ",
Arsenic,1019735,"Arsenate toxicity in human erythrocytes: Characterization of morphologic changes and determination of the mechanism of damage Abstract: Chronic arsenic exposure is associated with alterations in peripheral circulation and vascular disease. Toxicity to the vasculature is documented, but the effect of arsenic on the erythrocyte has not been evaluated. To determine if arsenic was toxic to human erythrocytes and whether this could contribute to vascular disease, human erythrocytes were incubated in vitro with sodium arsenate, As(V), or sodium arsenite, As(III), and assessed for damage. After 5 h of incubation with 10 mM As(V) or As(III), significant cell death (hemolysis) only occurred in the As(V) treated cells. Morphologic changes were assessed by scanning electron microscopy and light microscopy. As(V) induced a classic discocyte-echinocyte transformation extending to the formation of sphero-echinocytes; these changes were concentration dependent. As(III) treatment also resulted in echinocyte formation but less extensive than in As(V) treated cells, and no sphero-echinocytes were formed. The observed damage was consistent with reported changes induced by ATP depletion, and measurement of ATP in these samples confirmed this as a mechanism of damage. As(V) treatment at concentrations as low as 0.01 mM for 5 h significantly depleted ATP, and As(III) was relatively ineffective in causing ATP depletion. Based on these three parameters, the erythrocyte was estimated to be as much as 1000 times more susceptible to As(V) than As(III). ATP is required for the cell to maintain membrane integrity and deform efficiently in circulation. The changes described here could contribute to vascular occlusion, ischemia, and tissue death associated with arsenic circulatory disorders.",
Arsenic,1508668,"Blood lead is significantly associated with metabolic syndrome in Korean adults: An analysis based on the Korea National Health and Nutrition Examination Survey (KNHANES), 2008 Abstract: ABSTRACT: BACKGROUND: Although an association between low-level environmental heavy metal exposure and the incidence of metabolic syndrome (MS) has been hypothesized, little research on this topic has been conducted on a population-wide level. METHODS: We analyzed MS status and whole blood lead, mercury, cadmium, manganese, and creatinine-adjusted urine arsenic concentrations in 1,405 subjects, &gt;= 20 years of age, who were registered for the Korea National Health and Nutrition Examination Survey, 2008. RESULTS: Various demographic and biochemical parameters were associated with MS and blood heavy metal status. After adjusting for these variables, lead was the only heavy metal that was significantly associated with MS. Lead concentrations in subjects with MS were significantly higher than those in subjects without MS (p = 0.015). The prevalence of MS and a moderate/high risk for cardiovascular disease, as determined by Framingham risk score, also increased significantly according to the logarithmic transformation of the lead quartile (p &lt; 0.001). The odds ratios and 95% confidence intervals for MS were 1.56 (0.90--2.71), 1.63 (0.94--2.83), and 2.57 (1.46--4.51) for the second, third, and fourth quartiles of the log-transformed lead quartile, respectively, as compared with those of the lowest quartile after multiple adjustments for confounding factors. Serum triglyceride level was the only MS diagnostic component significantly associated with lead level in a multiple linear regression analysis (p = 0.006). CONCLUSIONS: These findings suggest that a higher prevalence of MS is associated with higher blood lead levels in the Korean population.",
Arsenic,1020713,"Exposure to inorganic arsenic in soil increases urinary inorganic arsenic concentrations of residents living in old mining areas Abstract: The short term human exposure studies conducted on populations exposed to high concentrations of inorganic arsenic in soil have been inconsistent in demonstrating a relationship between environmental concentrations and exposure measures. In Australia there are many areas with very high arsenic concentrations in residential soil most typically associated with gold mining activities in rural areas. This study aimed to investigate the relationship between environmental arsenic and urinary inorganic arsenic concentrations in a population living in a gold mining area (soil arsenic concentrations between 9 and 9900 mg kg(-1)), and a control population with low arsenic levels in soil (between 1 and 80 mg kg(-1)). Risk factors for increased urinary arsenic concentrations were also explored. There was a weak but significant relationship between soil arsenic concentrations and inorganic urinary arsenic concentration with a Spearman correlation coefficient of 0.39. When participants with greater than 100 mg kg(-1) arsenic in residential soil were selected, the coefficient increased to 0.64. The geometric mean urinary inorganic arsenic concentration for the exposed group was 1.64 microg L(-1) (&lt;detection limit -28.4 microg L(-1)) and for the control group was 1.18 microg L(-1) (&lt;detection limit -4.69 microg L(-1)). Participants with residential soil in excess of 1000 mg kg(-1) recorded a geometric mean urinary inorganic arsenic concentration of 2.46 microg L(-1). In a random effects linear regression model, soil arsenic concentration was the significant predictor of increased urinary arsenic concentrations. Season was shown to have a significant influence on urinary inorganic arsenic concentrations. Other factors such as age, gender and hours of contact with soil may also be important risk factors. These results show that high concentrations of arsenic in soil can make a contribution to urinary inorganic arsenic concentrations.",
Arsenic,1936150,"Heavy metal and arsenic dispersion in a copper-skarn mining district in a Mexican semi-arid environment: Sources, pathways and fate Abstract: The Cu–Au rich ores of the Concepción del Oro mining district, located on the semi-arid Mexican Altiplano, have been mined for over 400 years. The residues of these activities were piled on the banks of the main stream that drains the area. The tailings piles are neither treated nor protected, so the waste material has been dispersed over the surroundings by seasonally occurring heavy rains and winds. A small town with 5,000 inhabitants has grown up around the mining operations. Mineralogical observations indicate that sulphates are the first products of alteration of the primary sulphides and that Fe hydroxides are the stable minerals that are formed after longer periods of time. At the present time, an area of about 40 km2 along both sides of the stream has being severely contaminated with Cu–As–Zn-rich tailings, indicating that the seasonal heavy rains are indeed the main dispersion factor. Contaminated soils reach Cu-concentrations of up to 100 times, and As-concentrations of up to 20 times the local natural values. Factor analysis and geostatistical methods helped to identify pollutant origins and sources. Extraction tests on polluted agricultural soils using acetic acid mobilized 5–10 % of the total As content, 0.5–2.75 and 1–4.5 % of Cu and Zn, respectively, indicating the potential of the biological activity of the soil to enhance the mobility of the elements mentioned, and, in this way, to get into the food chain and/or groundwater. Stabilization measures of the tailings heaps must be urgently undertaken in order to minimize the risk for the inhabitants of the region and to stop the pollution of a broader area.",
Arsenic,735040,"Nrf2 protects against As(III)-induced damage in mouse liver and bladder Abstract: Arsenic compounds are classified as toxicants and human carcinogens. Environmental exposure to arsenic imposes a big health issue worldwide. Arsenic elicits its toxic efforts through many mechanisms, including generation of reactive oxygen species (ROS). Nrf2 is the primary transcription factor that controls expression of a main cellular antioxidant response, which is required for neutralizing ROS and thus defending cells from exogenous insults. Previously, we demonstrated a protective role of Nrf2 against arsenic-induced toxicity using a cell culture model. In this report, we present evidence that Nrf2 protects against liver and bladder injury in response to six weeks of arsenic exposure in a mouse model. Nrf2(-/-) mice displayed more severe pathological changes in the liver and bladder, compared to Nrf2(+/+) mice. Furthermore, Nrf2(-/-) mice were more sensitive to arsenic-induced DNA hypomethylation, oxidative DNA damage, and apoptotic cell death. These results indicate a protective role of Nrf2 against arsenic toxicity in vivo. Hence, this work demonstrates the feasibility of using dietary compounds that target activation of the Nrf2 signaling pathway to alleviate arsenic-induced damage.",
Arsenic,1033226,"Heavy metal exposure in populations living around zinc and copper smelters Abstract: Arsenic, cadmium, and lead levels were determined simultaneously in multiple environmental media and human tissues in two zinc smelter (Bartlesville, Oklahoma and Palmerton, Pennsylvania) and two copper smelter (Ajo, Arizona and Anaconda, Montana) communities. Environmental media sampled included air, soil, household dust, and tap water; human samples included hair, blood, and urine. Between 200 and 300 residents from various age groups (1-5, 6-18, 20-40, and 60 + yr) were sampled in 1978 and 1979 and completed questionnaires in each of the four communities. Samples for all media were selected under a probability sampling framework at various distances from the smelters. Results of this investigation indicated that increased environmental levels and body burdens were exhibited at distances closest to the smelters. Of the three tissues sampled, hair was the most useful in determining relationships between environmental metal levels, distance, and body burden. Furthermore, while there was evidence that all ages had hair metal levels that were related to environmental levels and distance from the smelter, these relationships were much more pronounced for the 1- to 5-yr-old age group. The 1 to 5 yr olds also had the highest tissue metal levels across age groups. Higher hair metal levels were also found for males; smokers; children who ate paint, dirt, or clay; and for individuals who spent more time out of doors.",
Arsenic,2343567,"ASSESSMENT OF ENVIRONMENTAL POLLUTION OF WATER FROM IRRIGATION CANAL (ALEKSANDROVACKI CANAL, SERBIA) USING PHYTO-INDICATORS Abstract: The aim of this study was to carry out comparative assessment of pollution level of water from Aleksandrovacki canal, Serbia, using both chemical methods and phytoindicators, and to estimate its potential use for irrigation of four most commonly cultivated plant species in this area (maize, barley, cucumber and white mustard). The effect of water quality and/or pollution was assessed in bioassay, according to changes in physiological (seed germination energy, germination) and morphological parameters (root and shoot length -cm and fresh and dry weight of root and shoot-g) of tested species. The chemical analysis of water determined a high content of suspended substances, nutrients, ammonium ion, total nitrogen, organic matter with low degradability, total organic carbon, orthophosphates, total phosphorus, arsenic and chromium. The response of phyto-indicators to water quality and mixed pollution was species-dependant. Germination of maize, cucumber and white mustard was not under the influence of water quality, while barley seeds germinated in significantly lower percentage in water from the canal (95%) compared to the control (100%). Canals water inhibited root elongation of maize and barley and stimulated of white mustard (p&lt;0.01) compared to the control. Shoot length of barley, cucumber and white mustard was not under the influence of water quality (p&gt;0.05). Biomass was differently affected by water from the canal.",
Arsenic,1519133,"Effect of soil pH on As hyperaccumulation capacity in fern species, Pityrogramma calomelanos Abstract: Arsenic uptake by hyperaccumulator plant species depends on many different environmental factors. Soil pH is one of the most important factors due to its combined effect on both chemical and biological processes. In greenhouse experiment, the effect of pH (within the pH range 3.6 - 8.9) on As uptake as well as biomass of Pityrogramma calomelanos was evaluated. The plants were grown in mining soil containing 645.6 mg As kg(-1) for 14 weeks. Within this time, the plant biomass growth was 3.78 - 8.64 g d. wt. per plant and the removal amounted 6.3-18.4 mg As per plant. Translocation factor (ratio of As in fronds to roots) of the fern was 3.6 - 9.7, indicating its potential in phytoremediation of As contaminated soil. Influence of pH on As bioavailability was visible as the available As concentration was higher in acidic soil compared to alkaline soil. Furthermore, it was found that As accumulation by Pityrogramma calomelanos was optimum in the soil of pH 3.6. Nevertheless, the results of this study demonstrate that remediation of As-contaminated mining soils, by this fern, can be improved by changing the soil pH from 4.6 to 6.8.",
Arsenic,2278452,"Risk of second primary malignancies following a diagnosis of cutaneous malignant melanoma or nonmelanoma skin cancer in Alberta, Canada from 1979 to 2009 Abstract: Background Recent studies have revealed geographical variations with respect to the risk of second primary malignancies (SPMs) following cutaneous malignant melanoma (CMM) and nonmelanoma skin cancer (NMSC). <br> <br>Objectives To provide the largest analysis of the risk of SPM following skin cancers in Canada and to detect associations that may shed light on common pathogeneses between linked malignancies. <br> <br>Methods Relative risks for development of SPMs following a diagnosis of CMM or NMSC were calculated via a retrospective analysis of data retrieved from the Alberta Cancer Registry (ACR) from 1979 to 2009. <br> <br>Results From 1979 to 2009, 85 967 NMSC and 6884 CMM incident cases were recorded in the ACR. In total 19 869 SPMs were identified following a primary NMSC (7709 cutaneous and 12 160 noncutaneous), while 1437 SPMs (908 cutaneous and 529 noncutaneous) followed CMM. Patients with a previous history of skin cancer had a 60% increased risk of developing an SPM compared with those without [observed/expected ratio (O/E) 1.6, 95% confidence interval (CI) 1.6-1.7; P &lt; 0.001]. Thirty and 10 different SPMs were significantly identified to follow a diagnosis of NMSC and CMM, respectively. Patients under the age of 40 years with a prior history of CMM had a marked increased expectancy for SPM [O/E 5.6, 95% CI 4.5-7.0; P &lt; 0.001). <br> <br>Conclusions Further studies are warranted to identify environmental and molecular connections among linked cutaneous and noncutaneous malignancies, which may lead to earlier detection of related neoplasms via expanded screening protocols and development of shared treatment regimens. Heightened surveillance for the development of SPMs in patients with CMM under the age of 40 years should be considered.",
Arsenic,1597311,"Transcriptional regulation of the human ferritin gene by coordinated regulation of Nrf2 and protein arginine methyltransferases PRMT1 and PRMT4 Abstract: Antioxidant genes such as ferritin are transcriptionally activated in oxidative stress via the antioxidant responsive element (ARE), to which nuclear factor-E2-related factor 2 (Nrf2) binds and activates transcription. Histone modification plays a cooperative and essential role in transcriptional regulation; however, its role in antioxidant gene transcription remains elusive. Arsenic exposure activated ferritin transcription via the ARE concomitant with increased methylation of histones H4Arg3 (H4R3) and H3Arg17 (H3R17). To test our hypothesis that histone H4R3 and H3R17 methylation regulates ferritin transcription, H4R3 and H3R17 protein arginine (R) methyltransferases 1 and 4 (PRMT1 and PRMT4) were investigated. Arsenic exposure of human HaCaT keratinocytes induced nuclear accumulation of PRMT1 and PRMT4, histone H4R3 and H3R17 methylation proximal to the ARE, but not to the non-ARE regions of ferritin genes. PRMT1 or PRMT4 knockdown did not block Nrf2 nuclear accumulation but inhibited Nrf2 binding to the AREs by ?40% (P&lt;0.05), thus diminishing ferritin transcription in HaCaT and human primary keratinocytes and fibroblasts, causing enhanced cellular susceptibility to arsenic toxicity as evidenced by 2-fold caspase 3 activation. Focused microarray further characterized several oxidative stress response genes are subject to PRMT1 or PRMT4 regulation. Collectively, PRMT1 and PRMT4 regulate the ARE and cellular antioxidant response to arsenic.-Huang, B.-W., Ray, P. D., Iwasaki, K., Tsuji, Y. Transcriptional regulation of the human ferritin gene by coordinated regulation of Nrf2 and protein arginine methyltransferases PRMT1 and PRMT4.",
Arsenic,1020170,"Population-based biomonitoring in the Czech Republic: urinary arsenic Abstract: The method of Guo et aL (AnaL Chim. Acta, 1997, 349, 313-318) for the determination of the toxicologically relevant arsenic in urine was verified and then used for the determination of arsenic in urine of the Czech population for monitoring purposes. Statistical evaluation at the level alpha = 0.05 did not prove any significant differences between industrial and agricultural regions, between males and females and smokers and nonsmokers. Likewise no differences were found among children in all the regions monitored. In the adult population small differences were found between some regions but these differences were not dependent on industrial pollution. The values of toxicologically relevant arsenic are low for all regions. The summarised value of the median for all groups together is 3.5 microg (g creatinine)(-1).",
Arsenic,1026723,"Calcium carbide poisoning via food in childhood Abstract: The fast ripening of fruits means they may contain various harmful properties. A commonly used agent in the ripening process is calcium carbide, a material most commonly used for welding purposes. Calcium carbide treatment of food is extremely hazardous because it contains traces of arsenic and phosphorous. Once dissolved in water, the carbide produces acetylene gas. Acetylene gas may affect the neurological system by inducing prolonged hypoxia. The findings are headache, dizziness, mood disturbances, sleepiness, mental confusion, memory loss, cerebral edema and seizures. We report the case of a previously healthy 5 year-old girl with no chronic disease history who was transferred to our Emergency Department with an 8-h history of coma and delirium. A careful history from her father revealed that the patient ate unripe dates treated with calcium carbide.",
Arsenic,2225028,"Investigation on mechanism of Cr(VI) reduction and removal by Bacillus amyloliquefaciens, a novel chromate tolerant bacterium isolated from chromite mine soil Abstract: A strain CSB 9 isolated from chromite mine soil of Sukinda, India was identified as Bacillus amyloliquefaciens based on biochemical and 16S rRNA gene sequencing. The strain exhibited relatively high tolerance to Cr(VI) (?900mgL(-1)) and fast reduction rate of 2.22mg Cr(VI) L(-1)h(-1), under optimized conditions of 100mgL(-1) Cr(VI), pH 7 and temperature 35°C within 45h. Mechanism of Cr(VI) reduction as well as nature and fate of the reduced product were studied to determine the scope of removal of reduced Cr(III) end product. AAS analyses of the culture products treated with Cr(VI) for 45h showed the distribution of Cr(III) in pellet and culture supernatant to be 37.4±1.7 and 62.6±3.4mgL(-1), respectively. In SEM images, the bacterial pellets with Cr(VI) treatment appeared coagulated, rough and porous whereas the pellets without Cr(VI) treatment appeared regular, smooth and non-porous in structure. SEM-EDX of the bacterial precipitates under Cr(VI) treatment revealed immobilization of Cr(III) species on the bacterial cell surface. Further Raman spectroscopy analysis confirmed the presence of Cr(III) species, with characteristic peak at around 600cm(-1). TEM-EDX study of the bacterial precipitates under Cr(VI) treatment showed intracellular deposition of Cr(III) which are in nanometric range. Further characterization of reduced product by XRD, FT-IR and SAED analyses suggested the formation of poorly crystalline end products. A Cr(VI) removal mechanism considering both the surface immobilization and intracellular accumulation of Cr(III) along with the formation of coagulated cell precipitate by living B. amyloliquefaciens was suggested.",
Arsenic,1032234,"Serum-stimulated cell cycle progression and stress protein synthesis in C3H10T1/2 fibroblasts treated with sodium arsenite Abstract: In this work, we demonstrated that a nonlethal dose of arsenite administered to quiescent C3H10T1/2 fibroblasts can enhance the mitogenic effect of suboptimal concentrations of serum. The mitogenic effect was dependent on the serum concentration and on the time interval between the administration of arsenite and that of serum. This suggests that mitogen sensitivity changes in time after arsenite treatment. It is shown that the concentrations of arsenite that enhance the mitogenic effect of serum also increase the mRNA levels of c-fos, HSP68, and HSP84 and induce the specific synthesis of Heat Shock Proteins (HSPs). The physiological significance of this phenomenon is most likely to counteract the long-term toxic effect of arsenite by early induction of compensation for cell loss.",
Arsenic,1337692,"Albinism and disease causing pathogens in Tanzania: Are alleles that are associated with OCA2 being maintained by balancing selection? Abstract: Oculocutaneous albinism type 2 (OCA2) is present at significantly higher frequencies in sub-Saharan African populations compared to populations in other regions of the world. In Tanzania and other sub-Saharan countries, most OCA2 is associated with a common 2.7kb deletion allele. Leprosy is also in high prevalence in sub-Saharan African populations. The infectious agent of leprosy, Mycobacterium leprae, contains a gene, 38L, that is similar to OCA2. Hypopigmented patches of skin are early symptoms that present with infection of leprosy. In consideration of both the genetic similarity of OCA2 and the 38L gene of M. leprae and the involvement of pigmentation in both disorders, we hypothesized that the high rates of OCA2 may be due to heterozygote advantage. Hence, we hypothesized that carriers of the 2.7kb deletion allele of OCA2 may provide a protective advantage from infection with leprosy. We tested this hypothesis by determining the carrier frequency of the 2.7kb deletion allele from a sample of 240 individuals with leprosy from Tanzania. The results were inconclusive due to the small sample size; however, they enabled us to rule out a large protective effect, but perhaps not a small advantage. Mycobacterium tuberculosis is another infectious organism prevalent in sub-Saharan Africa that contains a gene, arsenic-transport integral membrane protein that is also similar to OCA2. Interestingly, chromosomal region 15q11-13, which also contains OCA2, was reported to be linked to tuberculosis susceptibility. Although variants within OCA2 were tested for association, the 2.7kb deletion allele of OCA2 was not tested. This led us to hypothesize that the deletion allele may confer resistance to susceptibility. Confirmation of our hypothesis would enable development of novel pharmocogenetic therapies for the treatment of tuberculosis, which in turn, may enable development of drugs that target other pathogens that utilize a similar infection mechanism as M. tuberculosis. From an evolutionary perspective, confirmation of our hypothesis may provide another example of heterozygote advantage.",
Arsenic,1015756,"Arsenic encapsulation using Portland cement with ferrous sulfate/lime and Terra-Bond™ technologies - Microcharacterization and leaching studies Abstract: This work reports the results of an investigation on the treatment and encapsulation of arsenic-containing materials by Portland cement with ferrous sulfate and lime (PFL) and Terra-Bond™, a commercially available patented technology. The arsenic materials included: chromated copper arsenate (CCA)-treated wood materials; scorodite-rich mine tailings from the La Trinidad Mine in California; and a soil/smelter dust mixture from the Anaconda Superfund site spiked with monosodium methyl arsenate (MSMA) to simulate an organoarsenic soil material. SEM/EDS and XRD spectra of PFL treated samples showed similarity across all three waste materials while Terra-Bond treated samples showed predominance of elemental sulfur. SEM/EDS of PFL treated samples showed that calcium was imbedded in the structure while micrographs of Terra-Bond treated samples showed the appearance of an epoxy material on the surface. The epoxy material appears to be responsible for encapsulating and reducing the leachability of arsenic. XANES spectra for the PFL treatment of CCA-containing samples showed that arsenic has a predominant pentavalent form (As +5), and the PFL treatment process did not alter the arsenic oxidation state. But, distinct differences were observed for XANES spectra of untreated and PFL treated scorodite-rich mine tailing which changed the arsenic coordination structure from a mixture of As (+3/+5) to exclusively As (+5). Both S/S techniques reduced the amount of arsenic released in the leaching tests. Most cases show lower amounts of arsenic released from wastes treated by the Terra-Bond™ technique when compared to the PFL technique. The pH of the solution significantly affected the leachability, with the amount of arsenic released increasing with pH. Sequential extraction results indicate that sodium hydroxide was favorable in releasing arsenic in the mine tailings. This is due to ligand displacement reactions of hydroxyl ions with arsenic species and high pH conditions that prevent the readsorption of arsenic.",
Arsenic,1353965,"Maf genes are involved in multiple stress response in human Abstract: The Maf protein family consists of eight transcription factors containing a basic-leucine zipper (bZIP) domain. We have previously reported that the mRNA to one of these members, mafG/adapt66, is induced by oxidative stress in hamster HA-1 cells. It has subsequently been reported that mafG is induced bystress that activates the expression of genes under the control of the antioxidant/electrophile response element (ARE/EpRE), and that small Maf proteins are present in ARE/EpRE-protein complexes. Here we extend these studies to assess the effects of various types of stress on maf mRNA induction in human cells. The oxidative stressor cadmium, and the heavy metals cadmium, zinc, and arsenite induced mafG RNA levels within two hours, and maximally at five hours for cadmium and zinc. This induction was observed for multiple transcripts including two not normally associated with mafG, suggesting that these stress agents induced the expression of other related maf family RNAs. Modest induction of mafG mRNA was also observed with heat shock but not calcium elevation. These results suggest that mafG is a human stress-response gene induced by multiple stress, and that several maf (proto-)oncogene members play an important role in cellular stress response.",
Arsenic,628572,"Arsenite-induced alterations of DNA photodamage repair and apoptosis after solar-simulation UVR in mouse keratinocytes in vitro Abstract: Our laboratory has shown that arsenite markedly increased the cancer rate caused by solar-simulation ultraviolet radiation (UVR) in the hairless mouse skin model. In the present study, we investigated how arsenite affected DNA photodamage repair and apoptosis after solar-simulation UVR in the mouse keratinocyte cell line 291.03C. The keratinocytes were treated with different concentrations of sodium arsenite (0.0, 2.5, 5.0 microM) for 24 hr and then were immediately irradiated with a single dose of 0.30 kJ/m2 UVR. At 24 hr after UVR, DNA photoproducts [cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs)] and apoptosis were measured using the enzyme-linked immunosorbent assay and the two-color TUNEL (terminal deoxynucleotide transferase dUTP nick end labeling) assay, respectively. The results showed that arsenite reduced the repair rate of 6-4PPs by about a factor of 2 at 5.0 microM and had no effect at 2.5 microM. UVR-induced apoptosis at 24 hr was decreased by 22.64% at 2.5 microM arsenite and by 61.90% at 5.0 microM arsenite. Arsenite decreased the UVR-induced caspase-3/7 activity in parallel with the inhibition of apoptosis. Colony survival assays of the 291.03C cells demonstrate a median lethal concentration (LC50) of arsenite of 0.9 microM and a median lethal dose (LD50) of UVR of 0.05 kJ/m2. If the present results are applicable in vivo, inhibition of UVR-induced apoptosis may contribute to arsenite's enhancement of UVR-induced skin carcinogenesis.",
Arsenic,90035,"Respiratory cancer in a cohort of copper smelter workers: Results from more than 50 years of follow-up Abstract: Several studies have linked inhalation of airborne arsenic with increased risk of respiratory cancer, but few have analyzed the shape of the exposure-response curve. In addition, since inhaled airborne arsenic affects systemic levels of inhaled arsenic, there is concern that inhaled arsenic may be associated with cancers of the skin, bladder, kidney, and liver, which have been linked to ingested arsenic. The authors followed 8,014 white male workers who were employed for 12 months or more prior to 1957 at a Montana copper smelter from January 1, 1938 through December 31, 1989. A total of 4,930 (62%) were deceased, including 446 from respiratory cancer. Significantly increased standardized mortality ratios (SMRs) were found for all causes (SMR = 1.14), all cancers (SMR = 1.13), respiratory cancer (SMR = 1.55), diseases of the nervous system and sense organs (SMR = 1.31), nonmalignant respiratory diseases (SMR = 1.56), emphysema (SMR = 1.73), ill-defined conditions (SMR = 2.26), and external causes (SMR = 1.35). Internal analyses revealed a significant, linear increase in the excess relative risk of respiratory cancer with increasing exposure to inhaled airborne arsenic. The estimate of the excess relative risk per mg/m3-year was 0.21/(mg/m3-year) (95% confidence interval: 0.10, 0.46). No other cause of death was related to inhaled arsenic exposure.",
Arsenic,1025523,"Direct speciation analysis of arsenic in sub-cellular compartments using micro-X-ray absorption spectroscopy Abstract: Identification of arsenic chemical species at a sub-cellular level is a key to understanding the mechanisms involved in arsenic toxicology and antitumor pharmacology. When performed with a microbeam, X-ray absorption near-edge structure (mu-XANES) enables the direct speciation analysis of arsenic in sub-cellular compartments avoiding cell fractionation and other preparation steps that might modify the chemical species. This methodology couples tracking of cellular organelles in a single cell by confocal or epifluorescence microscopy with local analysis of chemical species by mu-XANES. Here we report the results obtained with a mu-XANES experimental setup based on Kirkpatrick-Baez X-ray focusing optics that maintains high flux of incoming radiation (&gt;10(11)ph/s) at micrometric spatial resolution (1.5 x 4.0 microm(2)). This original experimental setup enabled the direct speciation analysis of arsenic in sub-cellular organelles with a 10(-15) g detection limit. mu-XANES shows that inorganic arsenite, As(OH)3, is the main form of arsenic in the cytosol, nucleus, and mitochondrial network of cultured cancer cells exposed to As2O3. On the other hand, a predominance of As(III) species is observed in HepG2 cells exposed to As(OH)3 with, in some cases, oxidation to a pentavalent form in nuclear structures of HepG2 cells. The observation of intra-nuclear mixed redox states suggests an inter-individual variability in a cell population that can only be evidenced with direct sub-cellular speciation analysis.",
Arsenic,1584933,"Utilization of natural and artificial adsorbents in the mitigation of arsenic leached from hydrothermally altered rock Abstract: We have developed the adsorption-layer system for the simple and effective disposal of excavated rocks containing hazardous pollutants like arsenic (As). In this study, adsorption properties of natural and artificial materials including their performance in an actual altered rock-adsorption layer setup were evaluated. The adsorption of As[V] and As[III] onto all adsorbents fitted well with the Langmuir isotherm, indicating monolayer adsorption and progressive saturation of adsorption sites. All adsorbents were capable of As[V] and As[III] sequestration, but As[V] was more strongly adsorbed than As[III] based on the Langmuir isotherm. Also, artificial adsorbents were more efficient per unit weight than the natural adsorbent. Using the Langmuir isotherms and sequential extraction results, appropriate adsorbent dosages were estimated and then applied to an actual altered rock-adsorption layer column setup. The leaching concentration of As was lowered below 10 mu g/L throughout the experiment regardless of the kind of adsorbent used. This suggests that the adsorption-layer system is a promising alternative to special landfills in the disposal of excavated rocks enriched with As.",
Arsenic,710901,"Differential effects of arsenic on cutaneous and systemic immunity: focusing on CD4+ cell apoptosis in patients with arsenic-induced Bowen's disease Abstract: Bowen's disease (BD), a carcinoma in situ of the skin, has been identified as an early lesion in arsenic carcinogenesis. Patients with arsenic-induced Bowen's disease (As-BD) showed both cutaneous and systemic immune dysfunctions. We set out to evaluate the interactions between keratinocytes and lymphocytes in the context of As-BD carcinogenesis. Our results showed that As-BD lesions demonstrated a significant dermal CD4+ cell, an essential regulator of proper tumor immunity, undergoing apoptosis. In addition, it was found that the As-BD patients have lower percentage of peripheral CD4+ cells as compared with control subjects. However, the CD4+ cells from As-BD patients were less susceptible to arsenic-induced apoptosis, due to reduced tumor necrosis factor receptor 1 expression. Interestingly, arsenic was found to induce Fas expression on CD4+ cells and increase the soluble Fas ligand (sFasL) production from keratinocytes. This sFasL-containing keratinocyte supernatant was able to induce comparable CD4+ cell apoptosis for both patients and controls. Using immunofluorescent staining, increased FasL was observed in keratinocytes of As-BD lesions and Fas was expressed among infiltrating CD4+ cells. Our findings suggested that systemically, the percentage of CD4+ cells was decreased in the peripheral blood of As-BD patients. These residual CD4+ cells were less susceptible to arsenic-induced apoptosis. However, once infiltrated into the As-BD lesions, the selective CD4+ cell apoptosis might be mediated by FasL from keratinocytes. This additional tumor-anti-immune phenomenon present in the cutaneous environment provides a reasonable explanation for frequent occurrence of arsenic cancers in the skin.",
Arsenic,2337155,"Level of fluoride and arsenic in household shallow well water in Wamiao and Xinhuai villages in Jiangsu Province, China Abstract: After previously excluding iodine and lead as confounding factors, the aim of the present study, conducted in June 2013, was to consider whether arsenic was a confounding factor in the studies of children's intelligence in Wamiao and Xinhuai. Fluoride and arsenic levels were measured in water samples from the 37 household shallow wells still in use for providing water for washing but not drinking, 17 in Wamiao and 20 in Xinhuai. The fluoride levels in the household shallow wells in Wamiao (2.28 +/- 044 mg/L, range: 1.66-3.18 mg/L) were significantly higher than those in Xinhuai (0.38 +/- 0.21 mg/L, range: 0.15-0.77 mg/L) (t=17.08, p=0.000). In contrast, the levels of arsenic in Xinhuai (16.40 +/- 19.11 mu g/L, range: 0-48.50 mu g/L) were significantly higher than those in Wamiao (0.24 +/- 0.26 mu g/L, range: 0-0.50 mu g/L) (t=3.48, p=0.001). In our 2003 study, in high-fluoride Wamiao (mean drinking water F=2.47 mg/L) the average IQ was 8.4 points lower (92.02 vs. 100.41) than in the low-fluoride Xinhuai (mean drinking water F=0.36 mg/L). These results make it very unlikely that the differences in IQ of the children living in Wamiao and Xinhuai are the result of differences in exposure to arsenic rather than to fluoride.",
Arsenic,1797804,"Epigenetic modifications of DAPK and p16 genes contribute to arsenic-induced skin lesions and nondermatological health effects Abstract: Over 26 million people in West Bengal, India are exposed to very high levels of arsenic through drinking water, leading to several deleterious endpoints including cancers. To elucidate the role of promoter methylation in arsenic induced dermatological and non-dermatological health effects, methylation status of p16 and DAPK genes were determined. A case-control study was conducted involving 72 individuals with arsenic-induced skin lesions (cases) and 50 individuals without skin lesions (controls), having similar arsenic exposure through drinking water. Methylation status was determined by bisulfite conversion of genomic DNA and methylation specific PCR. Expression of the genes was determined by realtime PCR and Western blot analysis. Associations between the promoter methylation status and non-dermatological health effects were determined from epidemiological survey data. Significant hypermethylation was found in the promoters of both DAPK and p16 genes in the cases compared to the controls resulting in down regulation of both the genes in the cases. There was a 3.4-fold decrease in the expression of DAPK and 2.2 fold decrease in gene expression of p16 in the cases compared to the controls, the lowest expression being in the cancer tissues. Promoter hypermethylation of the genes were also associated with higher risk of developing arsenic-induced skin lesions, peripheral neuropathy, ocular and respiratory diseases. This study for the first time makes an attempt to correlate epigenetic modifications of the tumor suppressor genes with dermatological and non- dermatological health outcomes in a population chronically exposed to arsenic.",
Arsenic,1579249,"NUP98-NSD1 gene fusion and its related gene expression signature are strongly associated with a poor prognosis in pediatric acute myeloid leukemia Abstract: The cryptic t(5;11)(q35;p15.5) creates a fusion gene between the NUP98 and NSD1 genes. To ascertain the significance of this gene fusion, we explored its frequency, clinical impact, and gene expression pattern using DNA microarray in pediatric acute myeloid leukemia (AML) patients. NUP98-NSD1 fusion transcripts were detected in 6 (4.8%) of 124 pediatric AML patients. Supervised hierarchical clustering analyses using probe sets that were differentially expressed in these patients detected a characteristic gene expression pattern, including 18 NUP98-NSD1-negative patients (NUP98-NSD1-like patients). In total, a NUP98-NSD1-related gene expression signature (NUP98-NSD1 signature) was found in 19% (24/124) and in 58% (15/26) of cytogenetically normal cases. Their 4-year overall survival (OS) and event-free survival (EFS) were poor (33.3% in NUP98-NSD1-positive and 38.9% in NUP98-NSD1-like patients) compared with 100 NUP98-NSD1 signature-negative patients (4-year OS: 86.0%, 4-year EFS: 72.0%). Interestingly, t(7;11)(p15;p15)/NUP98-HOXA13, t(6;11)(q27;q23)/MLL-MLLT4 and t(6;9)(p22;q34)/DEK-NUP214, which are known as poor prognostic markers, were found in NUP98-NSD1-like patients. Furthermore, another type of NUP98-NSD1 fusion transcript was identified by additional RT-PCR analyses using other primers in a NUP98-NSD1-like patient, revealing the significance of this signature to detect NUP98-NSD1 gene fusions and to identify a new poor prognostic subgroup in AML. © 2013 Wiley Periodicals, Inc.",
Arsenic,1936092,"Microbial effects on the release and attenuation of arsenic in the shallow subsurface of a natural geochemical anomaly Abstract: Critical factors leading to arsenic release and attenuation from the shallow subsurface were studied with multidisciplinary approach in the natural gold-arsenic geochemical anomaly at Mokrsko (Czech Republic). The results show that microbial reduction promotes arsenic release from Fe(III) (hydr)oxides and Fe(III) arsenates, thereby enhancing dissolved arsenic in the shallow groundwater at average concentration of 7.76 mg/L. In the organic-rich aggregates and wood particles, however, microbial sulfate reduction triggers the formation of realgar deposits, leading to accumulation of As in the distinct organic-rich patches of the shallow subsurface. We conclude that precipitation of realgar in the shallow subsurface of soil/sediment depends on specific and non-trivial combination of water and rock chemistry, microbial community composition and spatial organisation of the subsurface zone, where speciation in saturated environments varied on a centimeter scale from reduced (decomposed wood, H2S and realgar present) to oxidized (goethite and arsenate minerals are present).",
Arsenic,1339993,"Arsenic and lead contamination in urban soils of Villa de la Paz (Mexico) affected by historical mine wastes and its effect on children's health studied by micronucleated exfoliated cells assay Abstract: Environmental geochemical and health studies were carried out in urban areas of Villa de la Paz, S.L.P. (Mexico), where mining activities have been developed for more of 200 years, leading to the pollution of surface soil by arsenic and heavy metals (Pb, Cd, Cu, Zn). The analysis of urban soils to determine total and bioaccessibility concentrations of As and Pb, demonstrated a combined contribution of the natural and anthropogenic concentrations in the site, at levels higher than the environmental guideline values that provoke a human health risk. Contour soil mapping confirmed that historical mine waste deposits without environmental control measures, are the main source of pollution soil by As and Pb in the site. Exposure (Pb in blood and As in urine) and effect (micronucleated exfoliated cells assay) biological monitoring were then carried out in the childhood population of the site and in a control site. The exposure biological monitoring demonstrated that at least 20-30 % of children presented Pb and As exposure values higher than the national and international maximum intervention values. The effect biomonitoring by MEC assay confirmed that there is a genotoxic damage in local childhood population that could be associated with the arsenic exposure in the site.",
Arsenic,1579255,"FUS/TLS assembles into stress granules and is a prosurvival factor during hyperosmolar stress Abstract: FUsed in Sarcoma/Translocated in LipoSarcoma (FUS/TLS or FUS) has been linked to several biological processes involving DNA and RNA processing, and has been associated with multiple diseases, including myxoid liposarcoma and amyotrophic lateral sclerosis (ALS). ALS-associated mutations cause FUS to associate with stalled translational complexes called stress granules under conditions of stress. However, little is known regarding the normal role of endogenous (non-disease linked) FUS in cellular stress response. Here, we demonstrate that endogenous FUS exerts a robust response to hyperosmolar stress induced by sorbitol. Hyperosmolar stress causes an immediate re-distribution of nuclear FUS to the cytoplasm, where it incorporates into stress granules. The redistribution of FUS to the cytoplasm is modulated by methyltransferase activity, whereas the inhibition of methyltransferase activity does not affect the incorporation of FUS into stress granules. The response to hyperosmolar stress is specific, since endogenous FUS does not redistribute to the cytoplasm in response to sodium arsenite, hydrogen peroxide, thapsigargin, or heat shock, all of which induce stress granule assembly. Intriguingly, cells with reduced expression of FUS exhibit a loss of cell viability in response to sorbitol, indicating a prosurvival role for endogenous FUS in the cellular response to hyperosmolar stress. J. Cell. Physiol. © 2013 Wiley Periodicals, Inc.",
Arsenic,2149263,"Chemical Extraction of Arsenic from Contaminated Soils in the Vicinity of Abandoned Mines and a Smelting Plant Under Subcritical Conditions Abstract: Under subcritical conditions, we studied the chemical extraction of arsenic (As) from contaminated soils that were sampled from the vicinity of abandoned mines and a smelting plant in South Korea. The total initial concentrations of As in the soil samples from the Myungbong and Cheongyang mines and the Janghang smelting plant were 298.6, 145.6, and 103.7mg/kg, respectively. X-ray photoelectron spectroscopy analysis showed that the species of As identified in the soil was As(+V), including As2O5 and AsO4 (3-) (.) At 20 degrees C, only 27.4, 26.5, and 40.1% of the total As was extracted from the Myungbong, Cheongyang, and Janghang soil samples, respectively, with 100mM of NaOH. As the temperature was increased to 300 degrees C, the extraction efficiencies remarkably increased. However, to achieve the complete extraction of As from the soils, 100mM of citric acid, EDTA, or NaOH was needed at 200, 250, or 300 degrees C. Extraction with subcritical water at 300 degrees C resulted in incomplete extraction of As from the soils. The results of these experiments indicate that extraction mechanisms other than oxidative dissolution of As(+III) species may be responsible for the enhancement of As extraction. Our results suggest that subcritical water extraction combined with extracting reagents can effectively remediate As-contaminated soil regardless of the As species.",
Arsenic,8524,"A cohort study on mortality from cancer and other causes among workers at a metal refinery Abstract: A non-concurrent prospective study was made on deaths from cancer and other causes occurring among 2,675 male workers at a metal refinery from 1949 to 1971. The expected number of deaths computed by applying age- and cause-specific death rates of Japanese males to these workers was compared with the observed number of deaths. Among 839 copper smelters, significantly increased mortalities were noted for lung cancer (SMR = 1,189) and colon cancer, but nor for cancer of the stomach, liver (primary) and biliary passages, pancreas and skin or for leukemia, tuberculosis, cerebrovascular diseases, heart diseases and liver cirrhosis. A dose-response relationship was demonstrated between the mortality from lung cancer and the degree of exposure. A very high excess mortality from lung cancer (SMR = 2,500) was seen among copper smelters who were considered to have been most heavily exposed to arsenic or workers who had engaged in sintering and blast furnace operations for 15 years of more before 1949. The latent period of lung cancer was 37.6 years on average, and not related to level of exposure. Twenty-six of 29 deaths from lung cancer among copper smelters occurred after they had left the refinery. Other production workers and clerical workers showed no significant excess mortality from any kind of cancer.",
Arsenic,1022102,"Arsenic bioaccessibility in a gold mining area: a health risk assessment for children Abstract: High concentrations of total arsenic (As) have been measured in soils of gold mining areas of Brazil. However, bioaccessibility tests have not yet been conducted on those materials, which is essential for better health risk estimates. This study aimed at evaluating As bioaccessibility in samples from a gold mining area located in Brazil and assessing children's exposure to As-contaminated materials. Samples were collected from different materials (a control and four As-contaminated soils/sediments) found in a gold mine area located in Paracatu (MG), Brazil. Total and bioaccessible As concentrations were determined for all samples. The control soil presented the lowest As concentrations, while all other materials contained high total As concentrations (up to 2,666 mg kg(-1)) and low bioaccessible As percentage (&lt;4.2%), indicating a low risk from exposure of resident children next to this area. The calculated dose of exposure indicated that, except for the pond tailings, in all other areas, the exposure route considering soil ingestion contributed at most to 9.7% of the maximum As allowed ingestion per day (0.3 ?g kg(-1) BW day(-1)).",
Arsenic,1246931,"EVALUATION OF ARSENIC EFFECTS IN Vicia faba BY FTIR AND FTNIR SPECTROSCOPY Abstract: Arsenic is an ubiquitous and highly toxic metalloid widely distributed in the environment through both natural and anthropogenic pathways (Liu et al., 2004) and its presence in food composites is a matter of concerns to the well being of both humans and animals. In fact, As has been recently found in drinking water (network and groundwater) in some Italian regions, including Lazio (Central Italy), at concentration ranging between 25 and 80 mu g L-1, higher than the limits set by law (10 mu g L-1) where Arsenic-contaminated groundwaters are often used in agriculture to irrigate crops for food and animal consumption; this determines that arsenic can enter human food chain. Inorganic or organic species of the metalloid arsenic occur in the environment. Either inorganic or organic As occurs in the environment and inorganic forms (iAs) are more toxic than the organic ones (oAs). Most of the human health effects of arsenic have been established based on epidemiologic studies, which have shown a significant association between the consumption of arsenic through drinking water and cancers of the skin, lung, bladder, liver, and kidney, neurologic disease, cardiovascular disease, as well as other non-malignant diseases. Arsenic is not an essential element for plants and its over-concentration in soils can generate toxicity phenomena. Its translocation from soil to plant constitutes one of the main human exposure ways. In this research we evaluated the effects of As exposure on Vicia faba seedlings by means of infrared (FTIR) and near infrared (FTNIR) spectroscopy to investigate molecular modifications caused by the interactions of plant with As. Both techniques showed relevant molecular modifications depending on As exposure. Molecular modifications evidenced by FTIR spectroscopy were mainly related to modified structures involving methyl groups of polysaccharides proteins and lipids, resulting better evidenced in meristem root samples. However, seconds derivative FTIR spectra did not show modification of the secondary structure of proteins. The molecular modifications shown by FTNIR spectroscopy were mainly related to the bands of hydroxyl groups with carboxylic and methyl groups, involving hydrogen bonds between carbohydrates and nucleic acids and lipids. These molecular and structural modifications are determined by the direct introduction of As within the plant biomolecules.",
Arsenic,888762,"Effects of acetaminophen on reactive oxygen species and nitric oxide redox signaling in kidney of arsenic-exposed rats Abstract: We examined whether acetaminophen could alter renal oxidative stress induced by arsenic; also whether withdrawal of acetaminophen treatment can increase susceptibility of kidney to arsenic toxicity. Acetaminophen (400 and 1600 mg/kg) was co-administered orally to rats for 3 days after preexposure to arsenic (25 ppm) for 28 days (Phase-I) and thereafter, acetaminophen was withdrawn, but arsenic exposure was continued for another 28 days (Phase-II). Acetaminophen enhanced arsenic-induced lipid peroxidation, GSH depletion and ROS production and further decreased superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities. Increased peroxidation did not alter kidney weight, but increased serum urea nitrogen and creatinine. Arsenic did not alter basal, iNOS-mediated NO production or iNOS expression. Arsenic decreased cNOS-mediated NO release and eNOS expression in Phase-II. Acetaminophen increased their expressions and NO production in Phase-I. In Phase-II, arsenic-mediated effects on NO remained mostly unaffected with acetaminophen. Results reveal that acetaminophen enhanced the risk of arsenic-mediated oxidative stress in kidney. Discontinuation of acetaminophen administration also increased the susceptibility of kidney to nephrotoxic effect of arsenic. It appeared ROS were primarily responsible for oxidative stress in both the phases. NO may have a minor role in Phase-I, but does not contribute to redox signaling mechanism in Phase-II.",
Arsenic,1936197,ACCUMULATION FACTOR OF HEAVY METALS IN CAPOETA UMBLA FISH SPECIES Abstract: ,
Arsenic,2149120,"Determination of arsenate in water by anion selective membrane electrode using polyurethane-silica gel fibrous anion exchanger composite Abstract: Polyurethane (PU)-silica (Si gel) based fibrous anion exchanger composites were prepared by solid-gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU-Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1×10(-8)M to 1×10(-1)M), response time (45s) and working pH range (5-8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO4(3-)) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.",
Arsenic,8677,"The role of the methylation in the detoxication of arsenate in the rabbit Abstract: The biotransformation, tissue retention, intracellular binding and biokinetics of arsenic were studied in rabbits exposed to [74As]arsenate (0.4 mg As/kg body wt., i.v.). Inhibition of the methyltransferase activity by injection of periodate-oxidized adenosine (PAD) caused a marked decrease of the formation of [74As]dimethylarsinic acid (DMA), which gave rise to 1.5–4 times increased tissue levels of 74As. This is almost the same as reported for rabbits given arsenite in combination with PAD and was due to a rapid reduction of the arsenate to arsenite which bound to the tissues. Only about 30% of the arsenate given was excreted unchanged in the urine, indicating that a large part was reduced to AsIII. Thus the methylation to DMA seems to be almost as important for the detoxication following exposure to arsenate as that following exposure to arsenite. In the rabbits with normal methylating capacity 50–70% of the produced AsIII was methylated to DMA. The liver was the only organ in which DMA was present 1 h after the administration, indicating that this is the main site of the methylation. The DMA was rapidly cleared from all tissues except the thyroid.",
Arsenic,1704067,"Biogeochemical reductive release of soil embedded arsenate around a crater area (Guandu) in northern Taiwan using X-ray absorption near-edge spectroscopy Abstract: This study investigates biogeochemical reductive release of arsenate from beudantite into solution in a crater area in northern Taiwan, using a combination of X-ray absorption near-edge structure (XANES) and atomic absorption spectrometry. Total arsenic (As) concentrations in the soil were more than 200 mg/kg. Over four months of laboratory experiments, less than 0.8% As was released into solution after reduction experiments. The 71% to 83% As was chemically reduced into arsenite (As(III)) and partially weathering into the soluble phase. The kinetic dissolution and re-precipitation of As, Fe, Pb and sulfate in this area of paddy soils merits further study.",
Arsenic,627876,"Inorganic arsenite alters macrophage generation from human peripheral blood monocytes Abstract: Inorganic arsenite has caused severe inflammatory chronic poisoning in humans through the consumption of contaminated well water. In this study, we examined the effects of arsenite at nanomolar concentrations on the in vitro differentiation of human macrophages from peripheral blood monocytes. While arsenite was found to induce cell death in a culture system containing macrophage colony stimulating factor (M-CSF), macrophages induced by granulocyte-macrophage CSF (GM-CSF) survived the treatment, but were morphologically, phenotypically, and functionally altered. In particular, arsenite-induced cells expressed higher levels of a major histocompatibility complex (MHC) class II antigen, HLA-DR, and CD14. They were more effective at inducing allogeneic or autologous T cell responses and responded more strongly to bacterial lipopolysaccharide (LPS) by inflammatory cytokine release as compared to cells induced by GM-CSF alone. On the other hand, arsenite-induced cells expressed lower levels of CD11b and CD54 and phagocytosed latex beads or zymosan particles less efficiently. We also demonstrated that the optimum amount of cellular reactive oxygen species (ROS) induced by nM arsenite might play an important role in this abnormal monocyte differentiation. This work may have implications in chronic arsenic poisoning because the total peripheral blood arsenic concentrations of these patients are at nM levels.",
Arsenic,1337324,"Arsenic speciation in water and snow samples by adsorption onto PHEMA in a micro-pipette-tip and GFAAS detection applying large-volume injection Abstract: A miniaturized solid phase extraction procedure has been developed for ultra-trace determination of inorganic arsenic species. Arsenic(III) as pyrrolidinedithiocarbamate complex was selectively adsorbed on 30mg poly(hydroxyethyl methacrylate) (PHEMA) micro beads, which is simply packed into a micro-pipette-tip. The adsorbed arsenic was quantitatively eluted by 700?L 0.25M NH(3) and determined by graphite furnace atomic absorption spectrometry (GFAAS). Injection of larger volume (i.e., 50?L v.s. conventional 10-20?L) eluent into graphite furnace and the use of Mg(NO(3))(2) as chemical modifier have improved atomic absorption signal intensity (sensitivity as characteristic mass of 25pg) and precision (RSD of 2.6%, c=10?gL(-1), n=11). Total arsenic amount was determined after reduction of arsenic(V) to arsenic(III) by thiourea-HCl system. As(V) concentration was calculated by the difference between As(III) and total arsenic. The detection limit (3s) of the method was found as 10ngL(-1) As(III) with an enrichment factor of 86. The relative standard deviation and relative error for six replicate determinations of 0.5?gL(-1) As(III) were found to be 4.0% and -0.7%, respectively. The method was successfully applied to drinking water, snow and reference water (SEM-2011) samples. When the samples were spiked with 0.5 and 1.0?gL(-1) As(III) and As(V), the recoveries varied between 96 and 100%.",
Arsenic,2149185,"Alterations in apoptotic caspases and antioxidant enzymes in arsenic exposed rat brain regions: Reversal effect of essential metals and a chelating agent Abstract: Arsenic (As) widely studied for its effects as a neurotoxicant. The present study was designed to evaluate the protective effect of calcium, zinc or monoisoamyl dimercaptosuccinic acid (MiADMSA), either individually or in combination on As induced oxidative stress and apoptosis in brain regions (cerebral cortex, hippocampus and cerebellum) of postnatal day (PND) 21, 28 and 3 months old rats. Arsenic exposure significantly decreased the activities of superoxide dismutase (SOD) isoforms, catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) with increase in glutathione s transferase (GST) while lipid peroxidation (LPx), arsenic levels, mRNA expression of caspase 3 and 9 were significantly increased in different brain regions. Arsenic induced alterations in these parameters were greater in PND 28 and more pronounced in cerebral cortex. From the results it is evident that combined supplementation of calcium and zinc along with MiADMSA would be most effective compared to individual administration in reducing arsenic induced neurotoxicity.",1
Arsenic,1025454,"In vitro mitigation of arsenic toxicity by tea polyphenols in human lymphocytes Abstract: The groundwater arsenicals have brought dreadful misery for the people residing in the endemic regions of West Bengal, India. Arsenic-related anomalies include arsenicosis, hyperkera-tosis, gastric complications, liver fibrosis, peripheral neuropathy, and cancer. Some of these diseases have been frequently associated with overproduction of reactive oxygen species that cause DNA damage and improper functioning of body's antioxidant defense mechanism. Natural polyphenols present in tea serve as excellent antioxidants. In the present study, an attempt has been made to elucidate the role of representative polyphenols and extracts of green and black tea in modulating sodium arsenite (As III)-induced DNA damage in normal human lymphocytes. Comet assay was used to detect the DNA damage. Arsenic-induced oxidative stress was measured with generation of reactive oxygen species, lipid peroxidation, and activity of some antioxidant enzymes. Expression of some repair enzymes such as poly(ADP-ribose) polymerase and DNA polymerase beta was measured to assess the effect of tea on DNA repair. Tea afforded efficient reduction of As III-induced DNA damage in human lymphocytes. Tea also quenched the excessive production of reactive oxygen species by arsenic, reduced the elevated levels of lipid peroxidation, and increased the activity of antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase. Furthermore, tea enhanced recovery of DNA damage, which was indicative of repair as confirmed by unscheduled DNA synthesis and pronounced expression of DNA repair enzyme poly(ADP-ribose) polymerase. It is speculated that the antioxidant potential and repair-inducing capacity of tea might help in combating the severe genotoxic effects induced by arsenic in the human population.",
Arsenic,187073,"Regional metal concentrations in Parkinson's disease, other chronic neurological diseases, and control brains Abstract: Metal deficiency or toxicity states have been recognized as a cause of several neurological disorders and are suspected in others. We analyzed four brain regions (frontal cortex, caudate nucleus, substantia nigra, and cerebellum) in 36 human brains for concentrations of 24 metals (Ag, Al, As, B, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Pb, Mg, Mn, Mo, Na, Ni, P, Se, Ti, V, W, Zn). Regional metal concentrations, measured using atomic absorption and atomic emission spectroscopy, were compared between 9 Parkinson's disease (PD) brains, 15 brains from patients with other chronic neurological diseases, and 12 control brains. No significant metal concentration differences were noted between brains from PD and other chronic neurologic disease. However, parkinsonian brains (PD and parkinsonism secondary to neurofibrillary tangle disease) showed lower concentrations of magnesium in the caudate nucleus and copper in the substantia nigra than control brains. These findings may represent an etiologically important clue to parkinsonism.",
Arsenic,2215768,"Epidemiology of unilateral sensorineural hearing loss with universal newborn hearing screening Abstract: <strong>OBJECTIVES/HYPOTHESIS: </strong>Compare the epidemiology of pediatric unilateral sensorineural hearing loss before and after implementation of universal newborn hearing screening in Missouri.<br /><br /><strong>STUDY DESIGN: </strong>Inception cohort.<br /><br /><strong>METHODS: </strong>Charts of 134 children born between January 1, 1990 and December 31, 2007, diagnosed with unilateral sensorineural hearing loss at a single institution in Missouri were reviewed to determine the effects of universal newborn hearing screening on age of detection and etiology of hearing loss.<br /><br /><strong>RESULTS: </strong>Mean age of detection declined from 4.4 (standard deviation [SD] 1.8) to 2.6 (SD 2.6) years of age, whereas the rate of detection by 6 months of age increased from 3% to 42%. The majority (58%) of cases had normal hearing at birth. The most common etiological category was unknown (41%) before screening and congenital (45%) after screening. The use of magnetic resonance imaging has increased by 21% (2-fold), whereas use of computed tomography has declined by 8% since 2002. Yields of connexin, Pendred, electrocardiogram, and syphilis testing were 0/48 and 2/31 before and after screening, respectively.<br /><br /><strong>CONCLUSIONS: </strong>Implementation of universal newborn hearing screening in Missouri is associated with a decrease in age of detection of unilateral sensorineural hearing loss. The majority of cases are either not present or not detectable at birth. The combination of hearing status at birth and imaging findings suggests that the majority of cases are congenital rather than of unknown etiology.<br /><br /><strong>LEVEL OF EVIDENCE: </strong>2b. Laryngoscope, 124:295-300, 2014.",
Arsenic,2345717,"EVALUATION OF SOIL HEAVY METAL POLLUTION IN THE ZLATNA REGION Abstract: Soil contamination is a major problem not only at European but also at international level through the explosive development of the industry which led to the creation and proliferation of a wide and varied number of chemical compounds hazardous to the environment. Soil heavy metals contamination is the most dangerous pollution because those metals do not degrade like organic pollutants, their residence time in the soil being of thousands of years. The excess of heavy metals in soil can threaten the health of animals and humans, due to food chain transfer. Zlatna is a town located in the Alba county, at 35 km from the Alba Iulia city. The Ampoi river connects the two cities. The main heavy metals pollution sources in the area of Zlatna were the mining and mineral processing activities. The results show exceedance especially in the Zlatna town of lead content (3500 mg/kg), copper (12 970 mg/kg), zinc (3997 mg/kg) and arsenic (850 mg/kg). Also, they were passing in the alert or intervention threshold values for the Chemes village (6955 mg/kg - Cu) and arsenic in the most localities.",
Arsenic,2337150,"Removal of Arsenite from Water by Iron Modified Activated Carbon Fibre Abstract: Trivalent arsenic is a highly toxic pollutant with carcinogenicity and it is typically detected in ground water. It is most essential to remove As(III) effectively and efficiently before water distribution. In this study, activated carbon fibre was modified with iron salt (FeCl3) by wet impregnation method and used for As(III) removal by adsorption. The morphology of iron modified activated carbon fibre was not altered significantly by SEM measurement. By EDX analysis, the molar ratio of C, Fe and O on iron modified activated carbon fibre was observed to be 92.2, 0.70 and 7.1 %, respectively. The kinetics of adsorption experiment indicated that most of the uptake of As(III) occurred in the first 60 min. Pseudo-second-order model well fitted the kinetics data. The increase of solution pH caused an increase of As(III) adsorption capacity. Ionic strength test indicated that the adsorption process formed inner-sphere complexes. The presence of sulfate, carbonate and nitrate had insignificant influence on As(III) adsorption, while phosphate and silicate hindered the adsorption obviously. The Freundlich equation well described the adsorption isotherm. External electric field was proved to have improved the As(III) adsorption onto the sorbent and helped the desorption of As(III) as well.",
Arsenic,1345253,"alpha-Lipoic acid inhibits endotoxin-stimulated expression of iNOS and nitric oxide independent of the heat shock response in RAW 264.7 cells Abstract: The heat shock response protects against sepsis-induced mortality, organ injury, cardiovascular dysfunction, and apoptosis. Several inducers of the heat shock response, such as hyperthermia, sodium arsenite, and pyrollidine dithiocarbonate, inhibit NF-kappaB activation and nitric oxide formation. The antioxidant lipoic acid (LA) has recently been found to inhibit NF-kappaB activation and nitric oxide formation. We therefore tested the hypothesis that LA induces a heat shock response. To test this hypothesis, we determined whether exposure to LA affects expression of both heat shock protein 70 (HSP-70) and nuclear heat shock factor-1 (HSF-1) in lipopolysaccharide (LPS) stimulated macrophages. LA and hyperthermia attenuated LPS-induced increases in nuclear NF-kappaB, iNOS protein, and media nitrite concentrations. LPS and hyperthermia increased HSP-70 concentrations 8-fold and 20-fold, respectively. No effect of LA treatment alone on HSP-70 protein expression was detected. Likewise, no effect of LA on HSF-1 protein expression was detected. These data suggest that LA inhibits LPS-induced activation of iNOS in macrophages independent of the heat shock response.",
Arsenic,1508530,"Total and inorganic arsenic in dietary supplements based on herbs, other botanicals and algae-a possible contributor to inorganic arsenic exposure Abstract: The content of total and inorganic arsenic was determined in 16 dietary supplements based on herbs, other botanicals and algae purchased on the Danish market. The dietary supplements originated from various regions, including Asia, Europe and USA. The contents of total and inorganic arsenic was determined by inductively coupled plasma mass spectrometry (ICP-MS) and anion exchange HPLC-ICP-MS, respectively, were in the range of 0.58 to 5.0 mgkg(-1) and 0.03 to 3.2 mg?kg(-1), respectively, with a ratio between inorganic arsenic and total arsenic ranging between 5 and 100 %. Consumption of the recommended dose of the individual dietary supplement would lead to an exposure to inorganic arsenic within the range of 0.07 to 13 ?g?day(-1). Such exposure from dietary supplements would in worst case constitute 62.4 % of the range of benchmark dose lower confidence limit values (BMDL(01) at 0.3 to 8 ?g kg bw(-1) kg(-1) day(-1)) put down by European Food Safety Authority (EFSA) in 2009, for cancers of the lung, skin and bladder, as well as skin lesions. Hence, the results demonstrate that consumption of certain dietary supplements could contribute significantly to the dietary exposure to inorganic arsenic at levels close to the toxicological limits established by EFSA.",
Arsenic,1031709,"Theoretical significance of arsenic as a carcinogen Abstract: HEEP COPYRIGHT: BIOL ABS. There is prevalence of arsenical skin cancer in chronic arsenicism in Taiwan. The latter work is a statistical study in which it was found that the higher the content of As in drinking water, the greater the frequency of patients with skin cancer. A model of cancer is presented in which a functional operon which is interconnected with the mitotic operons is blocked. The exact nature of such a blockage is not discussed. Since As lies in the same column as P in the periodic table of the elements, a substitution for P in DNA is possible. Since As is a slightly larger atom than P, a sugar phosphate linkage may break. If such a break occurs in the proper location, a critical situation exists. If a break occurs in the operator region of a functional operon, difficulties occur. If a functional operon is interconnected with mitotic operons, the induction of cancer may result. The use of As as a substitute for P in the DNA molecule could illuminate the exact nature of blockage of the operon.",
Arsenic,628345,"Lifelong inorganic arsenic compounds consumption affected blood pressure in rats Abstract: Chronic arsenic exposure is a known risk factor for cardiovascular disease and has a strong correlation with hypertension. Oxidative stress may be one of the major contributors to arsenic-induced hypertension. To investigate the antioxidative and CYP systems through which inorganic arsenic compounds may contribute to blood pressure elevation in rats, we administered 50ppm arsenic (as arsenite and arsenate) in drinking water to Wistar rats for 200 successive days. Systolic blood pressure was determined every 20 days, and blood samples and tissues were collected at each time point for biological analysis. Compared to the control group, weight gain in the arsenic-exposed animals was slightly but significantly lower, whereas the relative weights of the various tissues was higher. Blood pressure was elevated until day 80 in both arsenic groups followed by a time-dependent change in the antioxidative enzyme system. The hypertensive effect remained until day 200 for arsenite when the change by arsenate was minimized. Patterns of antioxidative enzyme change differed between arsenite and arsenate. However, the most common marker of hypertension, the angiotensin-converting enzyme, showed no significant change in either arsenic group. CYP4A was highly expressed in both arsenic groups, particularly in the arsenite group. These results indicate that low but chronic arsenic exposure might cause elevated blood pressure and antioxidative interference. Furthermore, CYP4A might be more important than ACE in contributing to arsenic-induced hypertension.",
Arsenic,1344412,"Arsenite-induced reactive oxygen species and the repression of alpha-tocopherol in the MGC-803 cells Abstract: We have investigated the action of oxidative stress in arsenite-induced apoptosis of human gastric cancer MGC-803 cells. Cells exhibited obvious characteristic of apoptosis following the treatment with 1.0 microM arsenite for 24 h. During the process, low concentration of arsenite significantly increased superoxide formation and lipid peroxidation, which was dose-dependent and was related to cell apoptosis induced by arsenite. The oxidant-dependent increase in intracellular [Ca(2+)] level and p53 gene expression were also observed at the same time. A phospholipase C inhibitor, 1-[6-([(17 beta)-3-methoxyestra-1,3,5,(10)-trien-17-yl]-amino)hexyl]-2,5-dione (U73122), could block the rapid transient increase in intracellular Ca(2+) levels, as well as the subsequent fragmentation of nuclear DNA. Addition of alpha-tocopherol before arsenite treatment abolished the transient increase in superoxide formation, lipid peroxidation, intracellular [Ca(2+)] levels and p53 gene expression, and furthermore could significantly inhibited the arsenite-induced apoptosis of MGC-803 cells. These results indicate that arsenite-induced oxidative stress, which stimulate cellular signaling systems, are involved in apoptosis of MGC-803 cells.",
Arsenic,2279033,"Microvascular dysfunction with increased vascular leakage response in mice systemically exposed to arsenic Abstract: The mechanisms underlying cardiovascular disease induced by arsenic exposure are not completely understood. The objectives of this study were to investigate whether arsenic-fed mice have an increased vascular leakage response to vasoactive agents and whether enhanced type-2 protein phosphatase (PP2A) activity is involved in mustard oil-induced leakage. ICR mice were fed water or sodium arsenite (20 mg/kg) for 4 or 8 weeks. The leakage response to vasoactive agents was quantified using the Evans blue (EB) technique or vascular labeling with carbon particles. Increased EB leakage and high density of carbon-labeled microvessels were detected in arsenic-fed mice treated with mustard oil. Histamine induced significantly higher vascular leakage in arsenic-fed mice than in water-fed mice. Pretreatment with the PP2A inhibitor okadaic acid or the neurokinin 1 receptor (NK1R) blocker RP67580 significantly reduced mustard oil-induced vascular leakage in arsenic-fed mice. The protein levels of PP2Ac and NK1R were similar in both groups. PP2A activity was significantly higher in the arsenic-fed mice compared with the control group. These findings indicate that microvessels generally respond to vasoactive agents, and that the increased PP2A activity is involved in mustard oil-induced vascular leakage in arsenic-fed mice. Arsenic may initiate endothelial dysfunction, resulting in vascular leakage in response to vasoactive agents.",
Arsenic,1030745,"Arsenic induced apoptosis in malignant melanoma cells is enhanced by menadione through ROS generation, p38 signaling and p53 activation Abstract: INTRODUCTION: Resistance to apoptosis is a prominent feature of melanoma. Pharmacological concentration of arsenic in combination with a widely known oxidant, menadione was explored in this study to synergistically sensitize malignant melanoma cells to apoptosis. The molecular mechanism of apoptosis and the signaling-pathways involved were thoroughly investigated. MATERIALS METHODS AND RESULTS: Menadione synergized NaAsO(2) to significantly increase ROS generation and facilitate the major apoptotic signaling events: alteration of mitochondrial membrane potential, cytochrome c release and anti-apoptotic protein Bcl-2 down-regulation and subsequent activation of caspase-9 and caspase-3 followed by poly-ADP-ribose polymerase-1 cleavage. Antioxidant N-acetyl-L: -cysteine antagonized these events. Investigation of the signaling-pathway revealed significant suppression of AP-1 activity but not NF-kappaB upon NaAsO(2) and menadione application. An increase in p38 phosphorylation and p53 protein expression did also dictate the apoptotic response. Suppression of p38 activation with SB203580 and inhibition of p53 expression by siRNA attenuated apoptosis. Transfection of p53, in p53 null HCT cells augmented the apoptotic events. Moreover, the treatment also led to tumor size reduction in BALB/c mice developed by intra-dermal B16 mouse melanoma cell injection; however, it had no detectable pro-proliferative or pro-apoptotic effect on non-tumor keratinocytes, normal fibroblasts or PBMC. CONCLUSION: This study thus provides an insight into innovative mechanisms of melanoma sensitization, a proper cure against which is still elusive. Taken together, our data also provides the first evidence of arsenic activity accentuation by menadione through modulation of specific signaling-pathways.",
Arsenic,2064284,"Prepubertal exposure to arsenic(III) suppresses circulating insulin-like growth factor-1 (IGF-1) delaying sexual maturation in female rats Abstract: Arsenic (As) is a prevalent environmental toxin; readily accessible for human consumption and has been identified as an endocrine disruptor. However, it is not known what impact As has on female sexual maturation. Therefore, in the present study, we investigated the effects of prepubertal exposure on mammary gland development and pubertal onset in female rats. Results showed that prepubertal exposure to 10mg/kg of arsenite (As(III)) delayed vaginal opening (VO) and prepubertal mammary gland maturation. We determined that As accumulates in the liver, disrupts hepatocyte function and suppresses serum levels of the puberty related hormone insulin-like growth factor 1 (IGF-1) in prepubertal animals. Overall, this is the first study to show that prepubertal exposure to As(III) acts peripherally to suppresses circulating levels of IGF-1 resulting in delayed sexual maturation. Furthermore, this study identifies a critical window of increased susceptibility to As(III) that may have a lasting impact on female reproductive function.",
Arsenic,56078,"Chronic combined exposure to cadmium and arsenic exacerbates nephrotoxicity, particularly in metallothionein-I/II null mice Abstract: Cadmium (Cd) and arsenic (As) are important inorganic toxicants in the environment. Humans certainly have the potential to be exposed to the mixtures of Cd and As, but the toxicological interactions of these inorganic mixtures are poorly defined. Metallothionein (MT) is a cysteine-rich, metal-binding protein that plays an important role in Cd detoxication, but its role in As toxicity is less certain. To examine the role of MT in Cd- and/or As-induced nephrotoxicity, MT-I/II-knockout (MT-null) mice and background-matched wild-type (WT) mice were fed CdCl2 (100 ppm Cd) in the diet, NaAsO2 (22.5 ppm As) in the drinking water, or Cd plus As for 4 months. Subsequently, nephrotoxicity was examined by morphological and biochemical techniques. Chronic exposure to Cd produced more renal toxicity than As, and the combination of Cd and As produced even more renal injury than caused by either of the chemicals given alone. In mice receiving Cd plus As, proximal tubule degeneration and atrophy, glomerular swelling and interstitial fibrosis were more severe than those produced by either inorganic. Furthermore, lack of MT rendered MT-null mice more sensitive than WT mice to the nephrotoxicity produced by chronic Cd- and/or As-exposure. MT-null mice were especially susceptible to the toxicity produced by the combination of Cd and As, as evidenced by decreased body weight, enzymuria, glucosuria, proteinuria and nephropathy. In conclusion, this study indicates that As may potentiate Cd nephrotoxicity during the long-term, combined exposure, and that intracellular MT plays a role in decreasing the nephropathy of combined exposure to Cd and As.",
Arsenic,1251503,"Delayed neuronal death after brief histotoxic hypoxia in vitro Abstract: The effect of three metabolic inhibitors--iodoacetate, potassium cyanide, and potassium arsenate--on neuronal viability was studied in primary rat cortical and hippocampal CA1 neuronal cultures. Iodoacetate (0.1 mM) applied for 5 min to 8-day-old cultures resulted in delayed neuronal death within 3-24 h in cortical and hippocampal CA1 neurons. Neuronal degeneration was preceded by transient inhibition of energy metabolism to approximately 40% and a permanent inhibition of protein synthesis to approximately 50%. The inhibition of protein synthesis and the neuronal death were prevented by the free radical scavenger vitamin E but not by the glutamate antagonist MK-801. Removal of calcium during iodoacetate exposure could not protect against toxicity, and there was no increase of intracellular calcium concentration during and shortly after iodoacetate treatment. Cyanide and arsenate produced only partial neuronal degeneration, even at a dose of 10 mM. These observations demonstrate that brief exposure of neurons to low concentrations of iodoacetate produces a delayed type of neuronal death that is not mediated by either calcium or glutamate. The therapeutic effect of vitamin E points to a free-radical mediated injury and suggests that this type of pathology may also be involved in delayed neuronal death after transient energy depletion in vivo.",
Arsenic,628223,"Genotoxicity induced by arsenic compounds in peripheral human lymphocytes analysed by cytokinesis-block micronucleus assay Abstract: This work focuses on the analysis of genotoxic effects on human peripheral lymphocytes exposed in vitro to different arsenic (As) compounds by means of the cytokinesis-block micronucleus assay. The study was carried out by challenging peripheral human lymphocytes with six As compounds in trivalent or pentavalent forms such as arsenite (AsIII) and arsenate (AsV) and organoarsenic species such as monomethylarsonous acid (MMAsIII), monomethylarsonic acid (MMAsV), dimethylarsinic acid (DMAsV) and trymethylarsine oxide (TMAOV). For AsIII and AsV at concentrations of 4 and 32 ?M, respectively, an increase of micronuclei (MN) frequency was found. MMAsIII and MMAsV induced a statistically significant increase of MN frequency at the dose of 2 and 500 ?M, respectively. For DMAsV, no significant increase of MN was observed, although a decrease of the nuclear division index (NDI) was evident, indicating a cytotoxic effect. The genotoxic mechanism of action of MMAsIII was further evaluated by means of fluorescence in situ hybridization analysis. Due to a higher percentage of centromere-positive MN, MMAsIII showed a clear aneuploidogenic property. Finally, for TMAOV no genotoxicity was observed up to 1 mM. These results show how speciation is important in determining the genotoxic and cytotoxic effects of As compounds in human peripheral lymphocytes and support the emerging hypothesis that the induction of aneuploidy could be a mechanism by which As exerts its carcinogenic properties.",
Arsenic,1337731,"Stimulatory effects of arsenic-tolerant soil fungi on plant growth promotion and soil properties Abstract: Fifteen fungi were obtained from arsenic-contaminated agricultural fields in West Bengal, India and examined for their arsenic tolerance and removal ability in our previous study. Of these, the four best arsenic-remediating isolates were tested for plant growth promotion effects on rice and pea in the present study. A greenhouse-based pot experiment was conducted using soil inocula of individual fungi. The results indicated a significant (P&lt;0.05) increase in plant growth and improvement of soil properties in inoculated soils compared to the control. A significant increase in plant growth was recorded in treated soils and varied from 16-293%. Soil chemical and enzymatic properties varied from 20-222% and 34-760%, respectively, in inoculated soil. Plants inoculated with inocula of Westerdykella and Trichoderma showed better stimulatory effects on plant growth and soil nutrient availability than Rhizopus and Lasiodiplodia. These fungi improved soil nutrient content and enhanced plant growth. These fungi may be used as bioinoculants for plant growth promotion and improved soil properties in arsenic-contaminated agricultural soils.",
Arsenic,1794743,Simultaneous biodegradation of phenanthrene and oxidation of arsenite by a dual-functional bacterial consortium Abstract: ,
Arsenic,1024597,"In vitro genotoxicity assays to evaluate the role of vitamin A on arsenic in human lymphocytes Abstract: Ground water contamination of arsenic in drinking water is a burning problem worldwide; especially in West Bengal (India) and Bangladesh. The main endeavor in this study was to assess the role of vitamin A (2.72 microM/7 ml culture), a naturally occurring antioxidant upon arsenic-induced genotoxicity; with respect to chromosomal aberrations (structural and numerical) and micronuclei. Whole blood cultures set for 72 h were exposed to test chemicals for a period of 24 h ahead of harvesting. Arsenic concentrations tested in the present study are 0.36, 0.72 and 1.4 microM/7 ml culture. Mitomycin C (MMC), the direct acting mutagen was used as positive control. Our data indicates that at concentrations tested, arsenic-induced increase in the mean frequencies of these genotoxic indices were diminished by vitamin A, indicating its protective role towards cells from arsenic exerted injury.",
Arsenic,1070464,"Effect of vitamin E supplementation on arsenic induced oxidative stress in goats Abstract: The present study was designed to assess whether supplementation of different levels of vitamin E to long-term arsenic exposed goats affords protection against the oxidative stress caused by the metalloid. Twenty-four crossbred lactating goats were distributed randomly into four groups (control, T(1), T(2) and T(3)) of six in each. The animals in T(1), T(2) and T(3) were given 50 mg/kg DM arsenic daily, while in T(2) and T(3), vitamin E @100 IU and 150 IU/kg DM, respectively, was also supplemented additionally for the period of 12 months. Compared to control, significant (p < 0.05) decline in SOD (45 %), CAT activities of erythrocytes (63 %), plasma total Ig (22 %) and total antioxidant activity (24 %) was observed in only arsenic treated groups and vitamin E supplementation in both doses produced partial mitigation effect against SOD (23 %, 20 %) and CAT (39 %, 48 %) while complete mitigation against total Ig (16 %, 7 %) and antioxidant activity (10 %, 8 %) was found. Average lymphocyte stimulation index at the end of experiment was (p < 0.05) lower in arsenic exposed groups (1.003 ± 0.01) and significant (p < 0.05) recovery was observed in response of vitamin E supplementation at higher doses (1.138 ± 0.03). So, vitamin E is helpful in reducing the burden of arsenic induced oxidative stress and activities of antioxidant enzymes in goats.",
Arsenic,1070379,"Comparative transcriptome analysis of transporters, phytohormone and lipid metabolism pathways in response to arsenic stress in rice (Oryza sativa) Abstract: • Arsenic (As) contamination of rice (Oryza sativa) is a worldwide concern and elucidating the molecular mechanisms of As accumulation in rice may provide promising solutions to the problem. Previous studies using microarray techniques to investigate transcriptional regulation of plant responses to As stress have identified numerous differentially expressed genes. However, little is known about the metabolic and regulatory network remodelings, or their interactions with microRNA (miRNA) in plants upon As(III) exposure. • We used Illumina sequencing to acquire global transcriptome alterations and miRNA regulation in rice under As(III) treatments of varying lengths of time and dosages. • We found that the response of roots was more distinct when the dosage was varied, whereas that of shoots was more distinct when the treatment time was varied. In particular, the genes involved in heavy metal transportation, jasmonate (JA) biosynthesis and signaling, and lipid metabolism were closely related to responses of rice under As(III) stress. Furthermore, we discovered 36 new As(III)-responsive miRNAs, 14 of which were likely involved in regulating gene expression in transportation, signaling, and metabolism. • Our findings highlight the significance of JA signaling and lipid metabolism in response to As(III) stress and their regulation by miRNA, which provides a foundation for subsequent functional research.",
Arsenic,628443,"Pregnancy outcomes, infant mortality, and arsenic in drinking water in West Bengal, India Abstract: Between 2001 and 2003, the authors studied pregnancy outcomes and infant mortality among 202 married women in West Bengal, India. Reproductive histories were ascertained using structured interviews. Arsenic exposure during each pregnancy, including all water sources used, was assessed; this involved measurements from 409 wells. Odds ratios for spontaneous abortion, stillbirth, neonatal mortality, and infant mortality were estimated with logistic regression based on the method of generalized estimating equations. Exposure to high concentrations of arsenic (> or =200 microg/liter) during pregnancy was associated with a sixfold increased risk of stillbirth after adjustment for potential confounders (odds ratio (OR) = 6.07, 95% confidence interval (CI): 1.54, 24.0; p = 0.01). Arsenic-related skin lesions were found in 12 women who had a substantially increased risk of stillbirth (OR = 13.1, 95% CI: 3.17, 54.0; p = 0.002). The odds ratio for neonatal death was 2.81 (95% CI: 0.73, 10.8). No association was found between arsenic exposure and spontaneous abortion (OR = 1.01, 95% CI: 0.38, 2.70) or overall infant mortality (OR = 1.33, 95% CI: 0.43, 4.04). This study adds to the limited evidence that exposure to high concentrations of arsenic during pregnancy increases the risk of stillbirth. However, there was no indication of the increased rates of spontaneous abortion and overall infant mortality that have been reported in some studies.",
Arsenic,1704129,"Dietary total protein related to cancer mortality and cancers of digestive organs mortality in Bangladeshi adults: The Health Effects of Arsenic Longitudinal Study (HEALS) Abstract: The effect of dietary composition on mortality in Bangladesh and other low-income countries is largely unknown. Objective: We examined whether percentages of dietary energy derived from total protein and total fat were associated with all-cause and cancer mortalities in a Bangladeshi population. Methods: Participants were from the Health Effects of Arsenic Longitudinal Study (HEALS) cohort. Percentages of dietary energy derived from total protein and total fat were assessed using a validated food frequency questionnaire. Results: Percentage of dietary energy from protein appeared to be significantly associated with cancer mortality. Fully adjusted hazard ratios for cancer mortality in increasing tertiles of percentage of dietary energy from protein were 1.0 (reference), 1.14 (0.68, 1.91), and 1.81 (1.05, 3.11) (P for trend = 0.028). Additionally, the associations were particularly strong when analyses were restricted to deaths from cancers of the digestive organs. Fully adjusted hazard ratios for digestive organ cancer mortality in increasing tertiles of percentage of dietary energy from protein were 1.0 (reference), 2.24 (0.90, 5.58), and 4.79 (1.86, 12.34) (P for trend = 0.001). No significant associations in relation to mortality were observed for percentage of dietary energy from fat. Conclusion: Our findings show percentage of dietary energy from protein is an important risk factor or proxy to an important risk factor for cancer mortality in a rural Bangladeshi population.",
Arsenic,62167,Chromosome aberrations in psoriatic patients treated with arsenic Abstract: A significantly increased frequency of chromosomal aberrations was found in lymphocytes from eight psoriatic patients previously treated with arsenic than in lymphocytes from eight psoriatics with no such previous treatment. In most patients the arsenic therapy was discontinued more than 15 years ago. In the arsenic-treated group a statistically significant heterogeneity was found with respect to the frequency of aberrations. The frequency of sister chromatid exchange was not increased in the arsenic-treated patients.,
Arsenic,2149286,"The influence of solid matrices on arsenic toxicity to Corophium orientale Abstract: In marine ecosystems, benthic organisms are really important because they are the first step in the transfer of contaminants from environment to biota. To this end, this study focused on biological assays with the amphipod Corophium orientale exposed to two different molecules of arsenic: arsenate (AsV), the most abundant form in sediments, and dimethyl-arsinate (DMA), expected to be moderately toxic as an intermediate in the process of detoxification. The toxicity of arsenic compounds was measured after exposure to three different matrices: water, spiked natural sediment and inert spiked quartz sand. LC50 values were calculated for each exposure, and the results confirmed the highest toxicity of AsV, in addition to underlining the importance of matrix of exposure. Water exposure was the matrix which presented the highest toxicity for inorganic arsenic (AsV LC50=3.51 mg L?1 vs DMA LC50=54.65 mg L?1), spiked natural sediment demonstrated its capability to chelate arsenate toxicity (AsV LC50=34.27 mg kg?1 vs. DMA LC50=52.19 mg kg?1) and spiked quartz sand presented intermediate values for AsV (LC50=25.26 mg kg?1), whereas for DMA a lower toxicity was registered (LC50=872.35 mg kg?1). This study can provide some useful data linked with chemical speciation of arsenic and exposure matrix, for improving the correct management of contaminated sediment.",
Arsenic,1341640,"Accumulation of copper, chromium, and arsenic in blue mussels (Mytilus edulis) from laboratory and field exposures to wood treated with chromated copper arsenate type C Abstract: Laboratory and field experiments were conducted to examine the uptake of Cu, Cr, and As leached from southern yellow pine (SYP) treated with chromated copper arsenate type C (CCA-C), as well as effects on mortality and growth, in blue mussels (Mytilus edulis). Mussels were exposed to CCA-C-treated wood at a preservative retention of 40 kg/ml and control (nontreated) SYP in laboratory flow-through sea table and field exposure experiments for 9 months in 1994 and 3 months in 1995. Mussels were sampled at regular intervals to evaluate possible short- and long-term exposure effects. Individual mussels were measured to determine the length, dry weight, and condition index. Mussel tissues were then analyzed for Cu, Cr, and As. Results showed few significant differences in condition index, dry weight, and length between CCA-C-exposed and control mussels. In addition, no statistically significant differences in mortality were found between the mussels exposed to CCA-C-treated and nontreated SYP in the laboratory flow-through sea table and field exposure experiments. Significant differences in Cu, As, and Cr contents in mussel tissues between treatments were few, and generally cannot be attributed to exposure to CCA-C-treated SYP. The lack of Cu, Cr, and As uptake from CCA-C-treated SYP was attributed to the low, although continuous, rate of release of these elements from CCA-C-treated wood and to the experimental design, which allowed continuous flushing, prohibiting the accumulation of these elements in the water surrounding the mussels.",
Arsenic,1267621,TOXIC SUBSTANCES IN RIVERS AND STREAMS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM REVIEW AMMONIA ARSENIC CHLORINE NITRITE OZONE SULFIDE CYANIDE PHENOLS HEAVY METALS PESTICIDES HERBICIDES INSECTICIDES POLYCHLORINATED BIPHENYLS,
Arsenic,786533,"Metal sources and exposures in the homes of young children living near a mining-impacted Superfund site Abstract: Children living near hazardous waste sites may be exposed to environmental contaminants, yet few studies have conducted multi-media exposure assessments, including residential environments where children spend most of their time. We sampled yard soil, house dust, and particulate matter with aerodynamic diameter <2.5 in 59 homes of young children near an abandoned mining area and analyzed samples for lead (Pb), zinc (Zn), cadmium (Cd), arsenic (As), and manganese (Mn). In over half of the homes, dust concentrations of Pb, Zn, Cd, and As were higher than those in soil. Proximity to mine waste (chat) piles and the presence of chat in the driveway significantly predicted dust metals levels. Homes with both chat sources had Pb, Zn, Cd, and As dust levels two to three times higher than homes with no known chat sources after controlling for other sources. In contrast, Mn concentrations in dust were consistently lower than in soil and were not associated with chat sources. Mn dust concentrations were predicted by soil concentrations and occupant density. These findings suggest that nearby outdoor sources of metal contaminants from mine waste may migrate indoors. Populations farther away from the mining site may also be exposed if secondary uses of chat are in close proximity to the home.",
Arsenic,1021473,"Protective role of sinapic acid against arsenic: induced toxicity in rats Abstract: Arsenic compounds are classified as toxicants and human carcinogens. Environmental exposure to arsenic imposes a big health issue worldwide. Sinapic acid is a phenylpropanoid compound and is found in various herbal materials and high-bran cereals. It has been reported that sinapic acid has antioxidant efficacy as metal chelators due to the orientation of functional groups. However, it has not yet been examined in experimental animals. In light of this fact, the purpose of this study was to characterize the protective role of sinapic acid against arsenic induced toxicity in rats. Rats were orally treated with arsenic alone (5mg/kg body weight (bw)/day) plus sinapic acid at different doses (10, 20 and 40mg/kg bw/day) for 30days. Hepatotoxicity was measured by the increased activities of serum hepatospecific enzymes namely aspartate transaminase, alanine transaminase, alkaline phosphatase, gamma glutamyl transferase, lactate dehydrogenase and total bilirubin along with increased elevation of lipid peroxidative markers, thiobarbituric acid reactive substances, lipid hydroperoxides, protein carbonyl content and conjugated dienes. The toxic effect of arsenic was also indicated by significantly decreased activities of enzymatic antioxidants like superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase and glucose-6-phosphate dehydrogenase along with non-enzymatic antioxidant like reduced glutathione. Administration of sinapic acid exhibited significant reversal of arsenic induced toxicity in hepatic tissue. The effect at a dose of 40mg/kgbw/day was more pronounced than the other two doses (10 and 20mg/kgbw/day). All these changes were supported by reduction of arsenic concentration and histopathological observations of the liver. These results suggest that sinapic acid has a protective effect over arsenic induced toxicity in rat.",
Arsenic,1579376,"As(III) and As(V) sorption on MnO2 synthesized by mechano-chemical reaction from aqueous phase Abstract: Nanoparticles of manganese-dioxide synthesized by mechano-chemical reaction were used for As(III) and As(V) sorption from water environment. The influence of a milling time of manganese-dioxide on sorption was examined with batch procedure. Sorption as a function of contact time was investigated. Kinetic of sorption, for both As(III) and As(V), was fast. The equilibrium condition for milled sorbents was achieved after one hour of mixing. Experimental data were fitted to Freundlich and Langmuir adsorption models. Both models represent experimental data well with slightly better regression coefficient for Freundlich isotherm model. With the increase of the milling time manganese-dioxide adsorption capacity for As(III) and As(V) increased. The decrease of average particle size with milling could be responsible for increase of sorption capacity. The influence of pH on sorption was also investigated. The sorption of both, As(III) and As(V), in investigated pH range (6.0-9.0) was not significantly disturbed and showed similar behaviour, what could indirectly imply oxidation of As(III) to As(V) before sorption.",
Arsenic,1372504,"Investigation of the effects of heat shock and agents which induce a heat shock response on the induction of differentiation of HL-60 cells Abstract: A heat shock of 42.5-43.5 degrees C for 1 h applied to HL-60 promyelocytic leukemia cells induced the appearance of between 13 and 34% (n = 6) of cells which showed characteristics of mature metamyelocytes/granulocytes. This is the first time a physical agent has been shown to induce the differentiation of this leukemic cell line. The treatment of HL-60 cells with a variety of agents which have been documented to stress cells and induce thermotolerance or a heat shock-like response also induced granulocyte-like differentiation: continuous treatment for 4 days with ethanol (213 mM), sodium arsenite (6 microM), cadmium sulfate (60 microM), lidocaine (3 mM), and procaine (5 mM) induced 73, 54, 14, 54, and 55% of cells, respectively, to reduce the dye nitro blue tetrazolium. They were also capable of the phagocytosis of yeast particles. Examination of differentiated cells showed that those treated with ethanol, arsenite, lidocaine, and procaine also expressed nonspecific esterase activity, typical of monocytes, but did not adhere to plastic and had a cellular and nuclear morphology consistent with differentiation to metamyelocytes. Analysis of protein synthesis of HL-60 cells treated with 170 mM N-methylformamide, by the pulse labeling of cells for 2 h with [14C]leucine at various times, showed that the constitutive synthesis of both the Mr 90,000 and 70,000 heat shock proteins fell substantially after 2 h of exposure to N-methylformamide. When HL-60 cells were incubated with 1 M N-methylformamide, a toxic concentration of this agent, or were heat shocked, the synthesis of both the Mr 70,000 and Mr 90,000 proteins was induced. We propose that changes in heat shock protein synthesis may be an important element of the induction of differentiation of HL-60 cells, particularly as these proteins have recently been shown to regulate the stability of oncogene proteins, such as myc (Lüscher, B., and Eisenman, R. N., Mol. Cell Biol., 8: 2504-2512, 1988).",
Arsenic,710820,"Arsenic exposure, dermatological lesions, hypertension, and chromosomal abnormalities among people in a rural community of northwest Iran Abstract: Chronic exposure to arsenic compounds is one of the major public-health problems in many developing and some developed countries. The aim of this study was to investigate the effects of chronic exposure to arsenic on dermatological lesions, hypertension, and chromosomal abnormalities among people in a community in the northwest of Iran. The occurrence of dermatological lesions, hypertension, and chromosomal abnormalities was investigated in two groups: Ghopuz village, including 101 subjects with chronic exposure to arsenic in drinking-water and Mayan village, including 107 subjects with no exposure. Daily/yearly absorbed amounts of arsenic were calculated for all subjects. Cumulative arsenic index for each individual was then estimated on the basis of age, water consumption, and location of residence. Arsenic concentration in drinking-water sources in Ghopuz and Mayan villages was 1031 +/- 1103 microg/L and non-detectable respectively. The mean systolic blood pressure in the exposure group [n=137, 95% confidence interval (CI 132-142)] was significantly higher than that in the control group (n=107, 95% CI 99.9-114). A similar significant difference was observed for diastolic blood pressure (exposed: n=82, 95% CI 79-85 vs non-exposed: n=71, 95% CI 66-75). The incidence of hyperkeratosis was 34 times higher among the exposure group compared to the control subjects [odds ratio (OR)=34, p&lt;0.001)]. A significant difference was also observed in the occurrence of skin-pigmentation between the two groups (OR=2.4, p&lt;0.007). Location and severity of the pigmentations were statistically different between the two groups. Twenty-five percent of the subjects in the exposure group showed chromosomal abnormalities (p=0.05). Arsenic exposure was a serious health problem in the region. More studies are needed to investigate the long-term effects and dose-response relationship of arsenic in the region and similar areas. Wide-ranging monitoring programmes for drinking-water sources should be implemented by public-health authorities.",
Arsenic,1017603,"Association of oxidative stress with realgar-induced differentiation in human leukemia HL-60 cells Abstract: <strong>BACKGROUND: </strong>Realgar (arsenic sulfide, As(4)S(4)) has been shown to have clinical efficacy in patients with newly diagnosed and relapsed acute promyelocytic leukemia. Mechanistic studies have demonstrated that realgar is able to induce cell differentiation.<br /><br /><strong>METHODS: </strong>The oxidative stress in the realgar-induced differentiation was examined with human leukemia HL-60 cells. Cell differentiation was evaluated by the expression of cell surface antigen CD11b and nitroblue tetrazolium assay. The activities of catalase and superoxide dismutase were measured spectrophotometrically. Flow cytometry was used to assess cell cycle distribution and apoptosis, the cellular level of reactive oxygen species (ROS) and glutathione, as well as mitochondrial transmembrane potential (MTP).<br /><br /><strong>RESULTS: </strong>The realgar-induced differentiation was enhanced by hydrogen peroxide, and preceded with drastic changes in ROS and catalase, as well as small changes in superoxide dismutase and the reduced form of glutathione. MTP values at 24 h were in linear proportion to the CD11b expression at 48 h when no apoptosis was observed.<br /><br /><strong>CONCLUSION: </strong>Oxidative stress and stress-related MTP decrease are associated with realgar-induced differentiation in HL-60 cells.",
Arsenic,1337919,"Spatial distribution and source identification of persistent pollutants in marine sediments of Hong Kong Abstract: A data matrix, obtained during a 3-year monitoring period (2007-2009) from 45 sampling sites in Hong Kong marine, was subjected to determine the spatial characterization and identify the sources of main pollutants. Indicator analyses indicated that polycyclic aromatic hydrocarbons (PAHs), nickel, manganese, and arsenic (As) were at safe levels. Five heavy metals (zinc, lead, cupper, cadmium, chromium (Cr)) were moderate to severe enrichment at some sites. Inner Deep Bay and Victoria Harbor were considered as hot spots for PAHs and the heavy metals, while Tolo Harbor was highly polluted by the heavy metals. Cluster analysis classified the 45 sampling sites into three groups, representing different pollution levels. Principal component analysis/factor analysis identified four principal components (PCs) and explained 84.9 % of the total variances, standing for persistent pollution, N factor, P and Cr factor, and As factor, respectively. Group A was highly polluted by persistent pollution, group B was the less polluted group, and subgroup B1 was less affected by PC3 and PC4 than subgroup B2. Group C, considered as the moderately polluted group, was greatly affected by N factor or persistent pollution, while subgroup C2 received more N pollution than subgroup C1.",
Arsenic,1704050,"Chitosan fiber-supported zero-valent iron nanoparticles as a novel sorbent for sequestration of inorganic arsenic Abstract: This study proposes a new sorbent for the removal of inorganic arsenic from aqueous solutions. Monodispersed nano zero-valent iron (nZVI) particles were nucleated at the surface of electrospun chitosan fibers (average fiber diameter of 195 ± 50 nm) by liquid phase reduction of FeCl3 using NaBH4. The material was characterized using SEM, TGA, XPS, XRD, and FTIR. The diameter of iron nanoparticles was found to vary between 75–100 nm. A set of batch experiments were carried out to elucidate the efficiency of the composite sorbent toward fixation of arsenite and arsenate ions. The ion concentrations in the supernatant solutions were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The results revealed that the chitosan fiber supported nZVI particles is an excellent sorbent material for inorganic arsenic uptake at concentrations ranging from 0.01 to 5.00 mg L?1 over a wide range of pH values. Based on XPS analysis, As(III) was found to undergo oxidation to As(V) upon sorption, while As(V) retained its oxidation state. By virtue of the successful combination of the electrospun fibers' mechanical integrity and the large reactivity of dispersed nZVI particles, the applicability of the resulting sorbent material in arsenic sorption holds broad promise.",
Arsenic,1020258,"Occupation, exposure to chemicals and risk of gliomas and meningiomas in Sweden Abstract: <strong>BACKGROUND: </strong>Occupational exposures may be related to the development of brain cancer. The objective was to estimate occupational-specific risk of gliomas and meningiomas among Swedish men and women gainfully employed in 1970 over the period 1971-1989, and the influence of occupational exposure to chemical substances.<br /><br /><strong>METHODS: </strong>A dataset linking cancer diagnoses from the Swedish national cancer register to occupational and demographical data obtained in the 1970 census was used to fit log-linear Poisson models, in order to obtain relative risks adjusted by age, period, geographical area and town size. Exposure to 13 chemicals was assessed using a Swedish job-exposure matrix.<br /><br /><strong>RESULTS: </strong>The main findings of this study among men were the increased risk of glioma with occupational exposure to arsenic, mercury, and petroleum products and of meningioma with lead. Women in occupational sectors with a higher socio-economic status showed an increased incidence of both, gliomas and meningiomas.<br /><br /><strong>CONCLUSIONS: </strong>Occupational exposure to some chemicals appeared to be related with an increased risk of glioma and meningioma in men. Exposures involved in glioma and meningioma development seemed to be different.",
Arsenic,1026316,"Effects of arsenic on seed germination and physiological activities of wheat seedlings Abstract: The effects of arsenic (As) were investigated on seed germination, root and shoot length and their biomass and some other factors to elucidate the toxicity of As. The results showed low concentrations of As (0-1 mg/kg) stimulated seed germination and the growth of root and shoot, however, these factors all decreased gradually at high concentrations of As (5-20 mg/kg). The contents of O2*-, MDA, soluble protein and peroxidase (POD) activity all increased with increasing As concentrations. Soluble sugar content, ascorbate peroxidase (APX), and superoxide dismutase (SOD) activities decreased at low concentrations of As, and increased at high concentrations of As. While acetylsalicylic acid (ASA) and chlorophyll contents, catalase (CAT) activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg, and then decreasing trend. By polyacrylamide gel electrophoresis (PAGE), As induced the expression of POD isozymes of wheat seedlings. As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg. However, As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg. The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.",
Arsenic,2215716,"Grape seed extract attenuates arsenic-induced nephrotoxicity in rats Abstract: Oxidative stress is a recognized factor in nephrotoxicity induced by chronic exposure to inorganic arsenic (As). Grape seed extract (GSE) possesses antioxidant properties. The present study was designed to evaluate the beneficial effects of GSE against arsenic-induced renal injury. Healthy, male Sprague-Dawley rats were exposed to As in drinking water (30 ppm) with or without GSE (100 mg/kg) for 12 months. The serum proinflammatory cytokine levels and mRNA expression levels of fibrogenic markers in the renal tissues were evaluated using enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. The protein expression levels of nicotinamide adenine dinucleotide phosphate (NADPH) subunits, transforming growth factor-?1 (TGF-?1) and phosphorylated Smad2/3 (pSmad2/3) were assessed using western blot analysis. The results demonstrated that cotreatment with GSE significantly improved renal function, as demonstrated by the reductions in relative kidney weight (% of body weight) and blood urea nitrogen, and the increase in the creatinine clearance capacity. GSE attenuated the As-induced changes in the serum levels of tumor necrosis factor-? (TNF-?), interleukin-6 (IL-6) and IL-1? and the mRNA levels of TGF-?1, ?-smooth muscle actin (?-SMA), connective tissue growth factor (CTGF) and fibronectin (FN) in renal tissue. Furthermore, administration of GSE markedly reduced As-stimulated reactive oxygen species (ROS) production and Nox activity, as well as the protein expression levels of the NADPH subunits (Nox2, p47phox and Nox4). In addition, GSE cotreatment was correlated with a significant reduction in TGF-?/Smad signaling, as demonstrated by the decreased protein levels of TGF-?1 and pSmad2/3 in renal tissue. This study indicated that GSE may be a useful agent for the prevention of nephrotoxicity induced by chronic exposure to As. GSE may exert its effects through the suppression of Nox and inhibition of TGF-?/Smad signaling activation.",
Arsenic,627333,"Heat shock protein 70 as an indicator of early lung injury caused by exposure to arsenic Abstract: Heat shock proteins (HSPs) are a family of highly conserved proteins that are induced by a number of stresses including toxic metals. Heat shock proteins expression has been reported to be an early and sensitive biomarker of cell stress. Arsenic is a naturally occurring metal that exists widely in the environment and is used in several industries. Exposure to arsenic is associated with the development of pulmonary cancers. We monitored changes in Hsp70 and markers of oxidative injury induced by arsenic in human pulmonary epithelial cells (BEAS-2B). Hsp70 protein, mRNA and reactive oxygen species (ROS) generation were measured after exposing cells to arsenic as markers of injury. Hsp70 protein expression showed significant 7.9-fold and 31.5-fold increase using Western blotting and ELISA assay, respectively, at a 50 microM As(III) with a 12 h exposure and an 12 h recovery time. Hsp70A and Hsp70B mRNA expression showed a two-fold increase and Hsp70C mRNA expression showed a six-fold increase. As(III)-induced Hsp70 protein expression was inhibited significantly by catalase and NAC, indicating mediation of ROS in Hsp70 expression. Intracellular glutathione (GSH) was significantly depleted by As(III) exposure. Lipid peroxidation by-product, 8-isoprostane, was increased six-fold at 24 h exposure to 20 microM As(III). Electron spin resonance and confocal microscope studies also showed As(III)-stimulated ROS generation. These results suggest that cellular injury by arsenic is mediated through ROS generation resulting in the expression of Hsp70. It is possible that Hsp70 may prove to be a sensitive biomarker for arsenic exposure with other markers of oxidative stress in human serum.",
Arsenic,1357163,"Results from the National Occupational Health Survey of Mining Abstract: The results of field surveys conducted under the National Occupational Health Survey of Mining (NOHSM) program were summarized. NOHSM was a series of surveys conducted by NIOSH to characterize potential exposures that could affect worker health (health related agents) at US mines. A representative sample of 491 US mines which extracted 66 different mineral commodities were surveyed from May 1984 through August 1989. The 491 mines included 431 metal and nonmetal mines and 60 coal mines and employed 59,734 workers. Each NOHSM survey consisted of three phases: a questionnaire, chemical inventory, and a worksite visit. The questionnaire sought information on medical services offered at the mine, industrial hygiene practices, and general information about the mine such as industrial classification, commodities mined or processed, and the size of the workforce. The chemical inventory collected information on all chemical substances and brand name products present. The worksite survey observed and interviewed workers to assess their potential exposures to physical agents such as noise, heat, or radiation, factors leading to musculoskeletal overloading, to welding or soldering fumes, to chemical substances, and to bulk mineral dusts. Altogether, 84,939 brand name products and 2,570 chemical substances were found at the mines. From 13 to 73% of the workers were potentially exposed to physical agents. Noise was the most prevalent exposure. From 18 to 39% of the workers were potentially exposed to factors causing musculoskeletal overload. Musculoskeletal overloading of the neck or back was the most prevalent potential exposure. Thirty two percent of the workers were potentially exposed to welding agents or cutting processes. Most of the chemical substances and brand name products were used as fuels and in maintenance. Of the bulk dust samples, 505 contained at least 5% quartz (14808607) and 38% contained more than 10% quartz. Arsenic (7440382) was found in 0.17 to 0.93% of the samples. Chrysotile (12001295) and other asbestiform minerals were found in 1.0 to 35.0% of the dust samples.",
Arsenic,1241326,"Arsenic accumulation and biological responses of watercress (Nasturtium officinale R. Br.) exposed to arsenite Abstract: The objective of the present study was to investigate biological responses of watercress (Nasturtium officinale R. Br.) under arsenic stress. Watercress samples were exposed to 1, 3, 5, 10, and 50 mu M of arsenite (As(III)) for 7 days. Arsenic accumulation in the leaves of watercress was investigated, and its influence on the rates of lipid peroxidation, ion leakage, photosynthetic pigmentation, proline content, enzymatic antioxidant performance, and DNA damage was examined. Watercress was capable of accumulating large amounts of arsenic in the leaves. The highest accumulation of As (1012 mu g g super(-1) dw) was found in the leaves of the plants exposed to 50 mu M of As(III). Plant growth was stimulated at 1 mu M As(III) application, while higher concentrations unfavorably affected plant growth. It was observed that exposure to As(III) significantly increased the ion leakage and lipid peroxidation compared to the control. An increase in protein and proline content was observed, followed by a gradual decline at higher concentrations. Stress conditions caused up-regulation of the antioxidant enzyme activity in dose dependent manner. The results indicated that the changes that occur in the random amplified polymorphic DNA (RAPD) profiles after an As(III) treatment, include the presence of certain modifications in the band intensity and the gain or loss of bands. The results of the present study confirmed that N. officinale is capable of overcoming the occurrence of As(III)-induced stress, especially, due to conditions of moderate exposure.",
Arsenic,2347582,"Transformation and removal of arsenic in groundwater by sequential anodic oxidation and electrocoagulation Abstract: Oxidation of As(III) to As(V) is generally essential for the efficient remediation of As(III)-contaminated groundwater. The performance and mechanisms of As(III) oxidation by an as-synthesized active anode, SnO2 loaded onto Ti-based TiO2 nanotubes (Ti/TiO2NTs/Sb-SnO2), were investigated. The subsequent removal of total arsenic by electrocoagulation (EC) was further tested. The Ti/TiO2NTs/Sb-SnO2 anode showed a high and lasting electrochemical activity for As(III) oxidation. 6.67?M As(III) in synthetic groundwater was completely oxidized to As(V) within 60min at 50mA. Direct electron transfer was mainly responsible at the current below 30mA, while hydroxyl radicals contributed increasingly with the increase in the current above 30mA. As(III) oxidation was moderately inhibited by the presence of bicarbonate (20mM), while was dramatically increased with increasing the concentration of chloride (0-10mM). After the complete oxidation of As(III) to As(V), total arsenic was efficiently removed by EC in the same reactor by reversing electrode polarity. The removal efficiency increased with increasing the current but decreased by the presence of phosphate and silica. Anodic oxidation represents an effective pretreatment approach to increasing EC removal of As(III) in groundwater under O2-limited conditions.",
Arsenic,2345639,"Correction to Predicting Geogenic Arsenic Contamination in Shallow Groundwater of South Louisiana, United States Abstract: ",
Arsenic,2064237,"FLVCR is necessary for erythroid maturation, may contribute to platelet maturation, but is dispensable for normal hematopoietic stem cell function Abstract: Heme is a pleiotropic molecule that is important for oxygen and oxidative metabolism, most notably as the prosthetic group of hemoglobin and cytochromes. Since, excess free intracellular heme is toxic, organisms have developed mechanisms to tightly regulate its concentration. One mechanism is through active heme export by FLVCR. Previously, we have shown that FLVCR is necessary for embryonic and post-natal erythropoiesis. However, FLVCR is also expressed in numerous other tissues, including hematopoietic stem cells (HSCs). To explore a possible role for FLVCR in HSC function, we performed serial, competitive repopulation transplant experiments using FLVCR-deleted and control bone marrow cells, along with wild-type competitor cells. Loss of FLVCR did not impact HSC function under steady-state or myelotoxic stress conditions (such as arsenic or radiation exposure), nor did FLVCR deletion result in alterations in the various progenitor compartments. However, even when 95% of the donor bone marrow cells lacked FLVCR, all red cells in recipient mice were wild-type. This is due to the increased apoptosis of FLVCR-deleted proerythroblasts. Also, remarkably, loss of FLVCR increased megakaryocyte ploidy. Together, these findings show FLVCR is redundant in stem cells, but has critical and contrasting stage-specific roles in discrete hematopoietic lineages.",
Arsenic,1366343,RADIOTRACER INVESTIGATION OF THE INTERFERENCE OF HYDROFLUORIC ACID IN THE DETERMINATION OF ARSENIC AND ANTIMONY BY HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM ENVIRONMENTAL SURVEILLANCE,
Arsenic,1327140,"Induction of mitotic arrest and aneuploidy by organic arsenic compounds in human lymphocytes Abstract: BIOSIS COPYRIGHT: BIOL ABS. Inorganic arsenic is methylated in the mammalian body to methylarsonic acid (MMA), dimethylarsinic acid (DMA) and trimethyl-arsine oxide (TMA). To achieve a more precise understanding of arsenic carcinogenicity, we examined the genotoxic effects of organic arsenic compounds on human lymphocytes by assessing induction of mitotic arrest, sister chromatid exchange (SCE) and aneuploidy. MMA, DMA and TMA arrested mitosis, DMA induced hyperdiploid cells, and DMA and TMA induced tetraploid cells. Of the three arsenic metabolites tested, DMA had the strongest effects on cell mitosis and aneuploidy induction. DMA arrested mitosis and induced c-mitosis significantly. These results suggest that DMA arrests mitosis and induces aneuploidy through spindle disruptions similar to those observed with known spindle poisons, such as colchicine or vinblastine. Since aneuploidy has been thought to be associated with tumor induction or neoplastic transformation, induction of aneuploidy by or",
Arsenic,1030814,"Evidence against the nuclear in situ binding of arsenicals--oxidative stress theory of arsenic carcinogenesis Abstract: A large amount of evidence suggests that arsenicals act via oxidative stress in causing cancer in humans and experimental animals. It is possible that arsenicals could bind in situ close to nuclear DNA followed by Haber-Weiss type oxidative DNA damage. Therefore, we tested this hypothesis by using radioactive (73)As labeled arsenite and vacuum filtration methodology to determine the binding affinity and capacity of (73)As arsenite to calf thymus DNA and Type 2A unfractionated histones, histone H3, H4 and horse spleen ferritin. Arsenicals are known to release redox active Fe from ferritin. At concentrations up to about 1 mM, neither DNA nor any of the three proteins studied, Type II-A histones, histone H3, H4 or ferritin, bound radioactive arsenite in a specific manner. Therefore, it appears highly unlikely that initial in situ binding of trivalent arsenicals, followed by in situ oxidative DNA damage, can account for arsenic's carcinogenicity. This experimental evidence (lack of arsenite binding to DNA, histone Type II-A and histone H3, H4) does not rule out other possible oxidative stress modes of action for arsenic such as (a) diffusion of longer lived oxidative stress molecules, such as H(2)O(2) into the nucleus and ensuing oxidative damage, (b) redox chemistry by unbound arsenicals in the nucleus, or (c) arsenical-induced perturbations in Fe, Cu or other metals which are already known to oxidize DNA in vitro and in vivo.",
Arsenic,1597284,"Nanoencapsulation of DMSA monoester for better therapeutic efficacy of the chelating agent against arsenic toxicity Abstract: Aims: Exposure to toxic metals remains a widespread occupational and environmental problem in world. Chelation therapy is a mainstream treatment used to treat heavy metal poisoning. This paper describes the synthesis, characterization and therapeutic evaluation of monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA)-encapsulated polymeric nanoparticles as a detoxifying agent for arsenic poisoning. Methods: Polymeric nanoparticles entrapping the DMSA monoester, which can evade the reticulo-endothelial system and have a long circulation time in the blood, were prepared. Particle characterization was carried out by transmission electron microscopy and dynamic light scattering. An in vivo study was conducted to investigate the therapeutic efficacy of MiADMSA-encapsulated polymeric nanoparticles (nano-MiADMSA; 50 mg/kg orally for 5 days) and comparison drawn with bulk MiADMSA. Swiss albino mice exposed to sodium arsenite for 4 weeks were treated for 5 days to evaluate alterations in blood, brain, kidney and liver oxidative stress variables. The study also evaluated the histopathological changes in tissues and the chelating potential of the nanoformulation. Results: Our results show that nano-MiADMSA have a narrow size distribution in the 50-nm range. We observed an enhanced chelating potential of nano-MiADMSA compared with bulk MiADMSA as evident in the reversal of biochemical changes indicative of oxidative stress and efficient removal of arsenic from the blood and tissues. Histopathological changes and urinary 8-OHdG levels also prove better therapeutic efficacy of the novel formulation for arsenic toxicity. Conclusion: The results from our study show better therapeutic efficacy of nano-MiADMSA in removing arsenic burden from the brain and liver. Original submitted: 22 August 2012; Revised submitted 14 January 2013.",
Arsenic,2279457,"Food sources of arsenic in pregnant Mediterranean women with high urine concentrations of this metalloid Abstract: Seafood consumption provides a significant amount of arsenic, although in its organic, nontoxic forms. Mediterranean populations may incorporate high levels of this metalloid as a consequence of seafood consumption. In the present study, the significance of this input among pregnant women from a Mediterranean city (Sabadell, Catalonia, Spain) is assessed. Total urinary arsenic was analyzed in 489 pairs of urine samples, corresponding to the 12th and 32th weeks of pregnancy. Association of arsenic content with seafood and other dietary items were studied. Geometric mean concentrations were 34 and 37 ?g/g creatinine during the first and third trimesters, respectively. The observed concentrations were similar to those reported in studies from other Mediterranean countries. The differences between both periods were not statistically significant. The only dietary factor significantly and positively associated with total urinary arsenic in both series of samples was seafood, particularly lean fish. Moreover, lean fish consumption during both periods was found to be the main determinant for differences in levels of arsenic between the first and third trimesters, which confirms the association between high levels of total urinary arsenic and seafood consumption.",
Arsenic,710813,"Arsenic exposure disrupts neurite growth and complexity in vitro Abstract: Arsenic has neurotoxic effects on both central and peripheral components of the mature nervous system. There is increasing evidence that exposure to arsenic is also toxic to the developing nervous system and can result in decreased cell division and increased apoptosis in cultured developing neurons. However, the effects of arsenic on subsequent neuron growth and morphology remain unclear. In the present study we used differentiating PC12 cells to investigate the effects of sodium arsenite on the early stages of neurite production and growth. We find that arsenic has concentration- and time-dependent effects on initial neurite outgrowth in vitro. Exposure to low micromolar levels of sodium arsenite for five days results in reduced neurite production, outgrowth and complexity in newly differentiating PC12 cells. Furthermore, we find that exposure of more mature PC12 cells to arsenite can inhibit further neurite development. These results suggest that exposure to arsenic can disrupt early stages of neuron differentiation by altering the normal progression of morphological development and could potentially contribute to compromised long term functioning of neurons.",
Arsenic,1337491,"Differential regulation of M3/6 (DUSP8) signaling complexes in response to arsenite-induced oxidative stress Abstract: Mitogen-activated protein kinase (MAPK) cascades are involved in the regulation of cellular proliferation, differentiation, survival, apoptosis, as well as in inflammatory responses. Signal intensity and duration have been recognized as crucial parameters determining MAPK signaling output. Phosphatases play a particularly important role in this respect, by tightly controlling MAPK phosphorylation and activation. M3/6 (DUSP8) is a dual-specificity phosphatase implicated in the dephosphorylation and inactivation of JNK and, to a lesser extent, p38 MAPKs and is found in a complex with these kinases, along with other pathway components, held together by scaffold proteins. The JNK family consists of three genes, giving rise to at least ten different splice variants. Some functional differences between these gene products have been demonstrated, but the underlying molecular mechanisms and the roles of individual splice variants are still incompletely understood. We have investigated the interaction of M3/6 with JNK isoforms, as well as scaffold proteins of the JNK interacting protein (JIP) family, in order to elucidate the contribution of M3/6 to the regulation of distinct JNK signaling modules. M3/6 exhibited stronger binding towards JNK1? and JNK2? isoforms and this was reflected in higher enzymatic activity towards JNK2?2 when compared to JNK1?1 in vitro. After activation of the pathway by exposure of cells to arsenite, the interaction of M3/6 with JNK1? and JNK3 was enhanced, whereas that with JNK1? or JNK2? decreased. The modulation of binding affinities was found to be independent of JNK-mediated M3/6 phosphorylation. Furthermore, arsenite treatment resulted in an inducible recruitment of M3/6 to JNK-interacting protein 3 (JIP3) scaffold complexes, while its interaction with JIP1 or JIP2 was constitutive. The presented data suggest an isoform-specific role for the M3/6 phosphatase and the dynamic targeting of M3/6 towards distinct JNK-containing signaling complexes.",
Arsenic,1677613,"Infection control for prevention of pancreatic fistula after pancreaticoduodenectomy Abstract: Background/Aims: Effectiveness of infection control for prevention of pancreatic fistula (PF) after pancreaticoduodenectomy (PD) is not clear. We analyzed the impact of infection on the development of PF and examined the effect of enhanced infection control to prevent PF. Methodology: Amylase level (D-amylase) and bacterial culture (D-culture) of drainage fluid were evaluated on POD 1, 3, 5 and 7, in 90 consecutive patients with soft pancreas who underwent PD. The study period was divided into two periods. The relationship between D-amylase and D-culture was examined, and the clinicopathological factors predicting PF were analyzed in the first period. Then, anti-infection measures were introduced in the second period, and the effect of enhanced infection control was examined. Results: Twenty-nine out of 58 patients (50.0%) developed PF in the first period. D-amylase were higher in patients with D-culture infection than in those without it (p&lt;0.05). D-amylase above 10,000IU/L on POD1 and D-culture infection on POD3 were independent predictive factors for PF by multivariate analysis (p&lt;0.01). After introduction of enhanced infection control in the second period, four out of 32 patients (12.5%) developed PF. The rates of PF and D-culture infection were significantly reduced (p&lt;0.05). Conclusions: Infection of drainage fluid is related to an increased level of amylase, resulting in PF. Enhanced infection control can effectively prevent PF after PD in soft pancreas.",
Arsenic,1339212,"Efflux of glutathione and glutathione complexes from human erythrocytes in response to inorganic arsenic exposure Abstract: The objective of the present study was to investigate if arsenic exposure results in glutathione efflux from human erythrocytes. Arsenite significantly depleted intracellular nonprotein thiol level in a time- and concentration-dependent manner. The intracellular nonprotein thiol level was decreased to 0.767?±?0.0017 ?mol/ml erythrocyte following exposure to 10 mM of arsenite for 4 h. Extracellular nonprotein thiol level was increased concomitantly with the intracellular decrease and reached to 0.481?±?0.0005 ?mol/ml erythrocyte in 4 h. In parallel with the change in extracellular nonprotein thiol levels, significant increases in extracellular glutathione levels were detected. Extracellular glutathione levels reached to 0.122?±?0.0013, 0.226?±?0.003, and 0.274?±?0.004 ?mol/ml erythrocyte with 1, 5, and 10 mM of arsenite, respectively. Dimercaptosuccinic acid treatment of supernatants significantly increased the glutathione levels measured in the extracellular media. Utilization of MK571 and verapamil, multidrug resistance-associated protein 1 and Pgp inhibitors, decreased the rate of glutathione efflux from erythrocytes suggesting a role for these membrane transporters in the process. The results of the present study indicate that human erythrocytes efflux glutathione in reduced free form and in conjugated form or forms that can be recovered with dimercaptosuccinic acid when exposed to arsenite.",
Arsenic,1343103,"Mixtures of arsenite and methyl methanesulfonate induce synergistic changes in Bcl2, p53, and pH2AX Abstract: ",
Arsenic,623413,"Dual Actions Involved in Arsenite-Induced Oxidative DNA Damage Abstract: Arsenic is a recognized human carcinogen, but the mechanism of carcinogenesis is not well understood. Oxidative stress and inhibition of DNA damage repair have been postulated as potential carcinogenic actions of arsenic. The present study tests the hypothesis that arsenite not only induces oxidative stress but also inhibits the activity of the DNA base excision repair protein, poly(ADP-ribose) polymerase-1 (PARP-1), leading to exacerbation of the oxidative DNA damage induced by arsenic. HaCat cells were treated with arsenite for 24 h before measuring 8-hydroxyl-2'-deoxyguanosine (8-OHdG), PARP-1 activity, and reactive oxygen species (ROS). Zinc supplementation and PARP-1 siRNA were used to increase or decrease, respectively, the PARP-1 protein's physiological function. At high concentrations (10 microM or higher), arsenite greatly induced oxidative DNA damage, as indicated by 8-OHdG formation. At lower concentrations (1 microM), arsenite did not produce detectable 8-OHdG, but was still able to effectively inhibit PARP-1 activity. Zinc supplementation reduced the formation of 8-OHdG, restored the PARP-1 activity inhibited by arsenite, but did not decrease ROS production. SiRNA knockdown of PARP-1 did not affect the 8-OHdG level induced by arsenic, while it greatly increased the 8-OHdG level produced by hydrogen peroxide indicating that PARP-1 is a molecular target of arsenite. Our findings demonstrate that in addition to inducing oxidative stress at higher concentrations, arsenite can also inhibit the function of a key DNA repair protein, PARP-1, even at very low concentrations, thus exacerbating the overall oxidative DNA damage produced by arsenite, and potentially, by other oxidants as well.",
Arsenic,2345687,"Recent history of sediment metal contamination in Lake Macquarie, Australia, and an assessment of ash handling procedure effectiveness in mitigating metal contamination from coal-fired power stations Abstract: This study assessed historical changes in metal concentrations in sediments of southern Lake Macquarie resulting from the activities of coal-fired power stations, using a multi-proxy approach which combines (210)Pb, (137)Cs and metal concentrations in sediment cores. Metal concentrations in the lake were on average, Zn: 67mg/kg, Cu: 15mg/kg, As: 8mg/kg, Se: 2mg/kg, Cd: 1.5mg/kg, Pb: 8mg/kg with a maximum of Zn: 280 mg/kg, Cu: 80 mg/kg, As: 21 mg/kg, Se: 5 mg/kg, Cd: 4 mg/kg, Pb: 48 mg/kg. The ratios of measured concentrations in sediment cores to their sediment guidelines were Cd 1.8, As 1.0, Cu 0.5, Pb 0.2 and Zn 0.2, with the highest concern being for cadmium. Of special interest was assessment of the effects of changes in ash handling procedures by the Vales Point power station on the metal concentrations in the sediments. Comparing sediment layers before and after ash handling procedures were implemented, zinc concentrations have decreased 10%, arsenic 37%, selenium 20%, cadmium 38% and lead 14%. An analysis of contaminant depth profiles showed that, after implementation of new ash handling procedures in 1995, selenium and cadmium, the main contaminants in Australian black coal had decreased significantly in this estuary.",
Arsenic,1519002,"Feedback Regulations of miR-21 and MAPKs via Pdcd4 and Spry1 Are Involved in Arsenite-Induced Cell Malignant Transformation Abstract: <strong>OBJECTIVE: </strong>To establish the functions of miR-21 and the roles of two feedback regulation loops, miR-21-Spry1-ERK/NF-?B and miR-21-Pdcd4-JNK/c-Jun, in arsenite-transformed human embryo lung fibroblast (HELF) cells.<br /><br /><strong>METHODS: </strong>For arsenite-transformed HELF cells, apoptosis, clonogenicity, and capacity for migration were determined by Hoechst staining, assessment of their capacity for anchorage-independent growth, and wound-healing, respectively, after blockage, with inhibitors or with siRNAs, of signal pathways for JNK/c-Jun or ERK/NF-?B. Decreases of miR-21 levels were determined with anti-miR-21, and the up-regulation of Pdcd4 and Spry1 was assessed in transfected cells; these cells were molecularly characterized by RT-PCR, qRT-PCR, Western blots, and immunofluorescence assays.<br /><br /><strong>RESULTS: </strong>MiR-21 was highly expressed in arsenite-transformed HELF cells and normal HELF cells acutely treated with arsenite, an effect that was concomitant with activation of JNK/c-Jun and ERK/NF-?B and down-regulation of Pdcd4 and Spry1 protein levels. However, there were no significant changes in mRNA levels for Pdcd4 and Spry1, which suggested that miR-21 regulates the expressions of Pdcd4 and Spry1 through translational repression. In arsenite-transformed HELF cells, blockages of JNK/c-Jun or ERK/NF-?B with inhibitors or with siRNAs prevented the increases of miR-21and the decreases of the protein levels but not the mRNA levels of Pdcd4 and Spry1. Down-regulation of miR-21 and up-regulations of Pdcd44 or Spry1 blocked the arsenite-induced activations of JNK/c-Jun or ERK/NF-?B, indicating that knockdown of miR-21 inhibits feedback of ERK activation and JNK activation via increases of Pdcd4 and Spry1 protein levels, respectively. Moreover, in arsenite-transformed HELF cells, inhibition of miR-21 promoted cell apoptosis, inhibited clonogenicity, and reduced migration.<br /><br /><strong>CONCLUSION: </strong>The results indicate that miR-21 is both a target and a regulator of ERK/NF-?B and JNK/c-Jun and the feedback regulations of miR-21 and MAPKs via Pdcd4 and Spry1, respectively, are involved in arsenite-induced malignant transformation of HELF cells.",
Arsenic,1378260,"Sodium Arsenite (AsIII) Modulatory Effect On The Heart And Blood Levels Of Glutathione In apoE(-/-)xLDLR(-/-) Mice Abstract: Arsenic is a potent toxicant, carcinogen and modulator of the antioxidant defense system and it may exert its toxicity by generating reactive oxygen species. Glutathione (GSH), a 3-amino acid thiol peptide, has been shown to have an important protective role against arsenic-induced oxidative damage. This study attempted to elucidate the impact of sub-acute (14-day) arsenic exposure on the blood and heart levels of GSH in apoE(-/-)xLDLR(-/-) mice. These double knockout mice are atherogenic and have been characterized as a model for investigating effects of arsenic on cardiovascular diseases such as atherosclerosis. Two groups, one saline and the other sodium arsenite (AsIII) treated apoE(-/-)xLDLR(-/-) mice were included in this study, 8 mice each. Each saline-treated mouse received an i.p. injection of 100 ?l saline and AsIII-treated mice received 1 mg arsenic per kg body weight via injection of adjusted volumes of a prepared arsenic stock solution. The mice were injected on a weekly basis for two weeks. The mice were bled, immediately sacrificed at the end of the second week and the hearts were collected. A GSH assay, measuring total non-protein thiols, was performed on the blood and heart samples of these mice. The assay for the blood samples showed a significant increase in GSH levels in arsenic-treated mice compared to the saline-treated group. Although there is a trend toward an increase in the heart GSH levels of the arsenictreated group compared to the control group, it is not statistically significant. The adaptive protective effect of GSH against this sub-acute exposure of arsenic is exhibited similarly in the blood and heart of these mice. It seems that due to possible arsenic-induced lipid peroxidation and oxidative stress, which can deplete GSH resources in these tissues shortly after exposure, the GSH compensating mechanisms are activated and increase GSH synthesis significantly in a time wise manner.",
Arsenic,2149270,"Asturian mercury mining district (Spain) and the environment: a review Abstract: Mercury is of particular concern amongst global environmental pollutants, with abundant contaminated sites worldwide, many of which are associated with mining activities. Asturias (Northwest of Spain) can be considered an Hg metallogenic province with abundant epithermal-type deposits, whose paragenetic sequences include also As-rich minerals. These mines were abandoned long before the introduction of any environmental regulations to control metal release from these sources. Consequently, the environment is globally affected, as high metal concentrations have been found in soils, waters, sediments, plants, and air. In this paper, a characterization of the environmental affection caused by Hg mining in nine Asturian mine sites is presented, with particular emphasis in Hg and As contents. Hg concentrations found in the studied milieu are similar and even higher than those reported in previous studies for other mercury mining districts (mainly Almadén and Idrija). Furthermore, the potential adverse health effects of exposure to these elements in the considered sites in this district have been assessed.",
Arsenic,1022081,"Environmental and biological monitoring of arsenic in outdoor workers exposed to urban air pollutants Abstract: The aim of this study is to evaluate personal exposure to As in urban air in two groups of outdoor workers (traffic policemen and police drivers) of a big Italian city through: (a) environmental monitoring of As obtained by personal samples and (b) biological monitoring of total urinary As. The possible influence of smoking habit on urinary As was evaluated. We studied 122 male subjects, all Municipal Police employees: 84 traffic policemen and 38 police drivers exposed to urban pollutants. Personal exposure to As in air was significantly higher in traffic policemen than in police drivers (p=0.03). Mean age, length of service, alcohol drinking habit, number of cigarettes smoked/day and BMI were comparable between the groups of subjects studied. All subjects were working in the same urban area where they had lived for at least 5yrs. Dietary habits and consumption of water from the water supply and/or mineral water were similar in traffic policemen and in police drivers. The values of total urinary As were significantly higher in traffic policemen (smokers and non smokers) than in police drivers (smokers and non smokers) (p=0.02). In the subgroup of non-smokers the values of total urinary As were significantly higher in traffic policemen than in police drivers (p=0.03). In traffic policemen and in police drivers total urinary As values were significantly correlated to the values of As in air (respectively r=0.9 and r=0.8, p<0.001). This is the first research in literature studying the exposure to As in outdoor workers occupationally exposed to urban pollutants, such as traffic policemen and police drivers. Personal exposure to As in the air, as well as the urinary excretion of As, is significantly higher in traffic policemen compared to drivers. These results can provide information about exposure to As in streets and in car for other categories of outdoor workers similarly exposed.",
Arsenic,1003594,"Overexpression of alfalfa mitochondrial HSP23 in prokaryotic and eukaryotic model systems confers enhanced tolerance to salinity and arsenic stress Abstract: The cloning and characterization of a gene (MsHSP23) coding for a heat shock protein in alfalfa in a prokaryotic and model plant system is described. MsHSP23 contains a 633 bp ORF encoding a polypeptide of 213 amino acids and exhibits greater sequence similarity to mitochondrial sHSPs from dicotyledons than to those from monocotyledons. When expressed in bacteria, recombinant MsHSP23 conferred tolerance to salinity and arsenic stress. Furthermore, MsHSP23 was cloned in a plant expressing vector and transformed into tobacco, a eukaryotic model organism. The transgenic plants exhibited enhanced tolerance to salinity and arsenic stress under ex vitro conditions. In comparison to wild type plants, the transgenic plants exhibited significantly lower electrolyte leakage. Moreover, the transgenic plants had superior germination rates when placed on medium containing arsenic. Taken together, these overexpression results imply that MsHSP23 plays an important role in salinity and arsenic stress tolerance in transgenic tobacco. This approach could be useful to develop stress tolerant crops including forage crops.",
Arsenic,1345081,"Lipid peroxidative damage by arsenic intoxication is countered by glutathione-glutathione-S-transferase system and metallothionein in the liver of climbing perch, Anabas testudineus Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenic (As) intoxication was examined in freshwater climbing perch (Anadas testudineus) following in vivo treatment for 2d at 1/10 LD50 and for 30d at 1/20 LC50. These exposures elicited no mortality, nor any apparent physiological distress. Lipid peroxidation (LPO), in terms of the production of malondialdehyde (MDA) and conjugated diene (CD), as the intoxication response, was prominent only after 48h at an arsenic dose of 1/10 LC50. This was accompanied by a significant decline in the level of reduced glutathione (GSH) in the fish, with no change in the glutathione-S-transferase (GST) activity. In the 30-d exposure, the increase in LPO activity at day 15 was not significant but there was significant increase in GSH accompanied by a significant stimulation of GST activity. Interestingly, the induction of metallothionein (MT) by As was already evident during the short term exposure, and the response further stabilized during the chronic exposure. The results clearly i",
Arsenic,622622,"PI-3K/Akt Pathway-Dependent Cyclin D1 Expression Is Responsible for Arsenite-Induced Human Keratinocyte Transformation Abstract: BACKGROUND: Long-term exposure of arsenite leads to human skin cancer. However, the exact mechanisms of arsenite-induced human skin carcinogenesis remain to be defined. OBJECTIVES: In this study, we investigated the potential role of PI-3K/Akt/cyclin D1in the transformation of human keratinocytic cells upon arsenite exposure. METHODS: We used the soft agar assay to evaluate the cell transformation activity of arsenite exposure and the nude mice xenograft model to determine the tumorigenesis of arsenite-induced transformed cells. We used the dominant negative mutant and gene knockdown approaches to elucidate the signaling pathway involved in this process. RESULTS: Our results showed that repeated long-term exposure of HaCat cells to arsenite caused cell transformation, as indicated by anchorage-independent growth in soft agar. The tumorigenicity of these transformed cells was confirmed in nude mice. Treatment of cells with arsenite also induced significant activation of PI-3K and Akt, which was responsible for the anchorage-independent cell growth induced by arsenite exposure. Furthermore, our data also indicated that cyclin D1 is an important downstream molecule involved in PI-3K/Akt-mediated cell transformation upon arsenite exposure based on the facts that inhibition of cyclin D1 expression by dominant negative mutants of PI-3K, and Akt, or the knockdown of the cyclin D1 expression by its specific siRNA in the HaCat cells resulted in impairing of anchorage-independent growth of HaCat cells induced by arsenite. CONCLUSION: Our results demonstrate that PI-3K/Akt-mediated cyclin D1 expression is at least one key event implicated in the arsenite human skin carcinogenic effect. [ABSTRACT FROM AUTHOR] Copyright of Environmental Health Perspectives is the property of Superintendent of Documents and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1070351,"Phytoavailability of antimony and heavy metals in arid regions: The case of the Wadley Sb district (San Luis, Potosí, Mexico) Abstract: This paper presents original results on the Sb and heavy metals contents in sediments and waste tailings, plants and water from the giant Wadley antimony mine district (San Luis Potosí State, Mexico). The dominant antimony phases in mining wastes are stibiconite, montroydite and minor hermimorphite. The waste tailings contain high concentrations of metals and metalloids (antimony, iron, zinc, arsenic, copper, and mercury). Manganese, copper, zinc, and antimony contents exceed the quality guidelines values for groundwater, plants and for waste tailings. Results indicate that peak accumulation is seasonal due to the concentration by high metabolism plants as Solanaceae Nicotiana. The metal phytoavailability in waste tailings is highly dependant on the metal speciation, its capability to be transported in water and, more particularly, the plant metabolism efficiency.",
Arsenic,735033,"Distribution and metabolism of four different dimethylated arsenicals in hamsters Abstract: Arsenic toxicity and distribution are highly dependent on animal species and its chemical species. Recently, thioarsenical has been recognized in highly toxic arsenic metabolites, which was commonly found in human and animal urine. In the present study, we revealed the mechanism underlying the distribution and metabolism of non-thiolated and thiolated dimethylarsenic compounds such as dimethylarsinic acid (DMAV), dimethylarsinous acid (DMAIII), dimethylmonothioarsinic acid (DMMTAV), and dimethyldithioarsinic acid (DMDTAV) after the administration of them into femoral vein of hamsters. DMAV and DMDTAV distributed in organs and body fluids were in their unmodified form, while DMAIII and DMMTAV were bound to proteins and transformed to DMAV in organs. On the other hand, DMAV and DMDTAV were mostly excreted into urine as their intact form 1 h after post-injection, and more than 70% of the doses were recovered in urine as their intact form. By contrast, less than 8–14% of doses were recovered in urine as DMAV, while more than 60% of doses were distributed in muscles and target organs (liver, kidney, and lung) of hamsters after the injection of DMMTAV and DMAIII. However, in red blood cells (RBCs), only a small amount of the arsenicals was distributed (less than 4% of the doses) after the injection of DMAIII and DMMTAV, suggesting that the DMAIII and DMMTAV were hardly accumulated in hamster RBCs. Based on these observations, we suggest that although DMMTAV and DMDTAV are thioarsenicals, DMMTAV is taken up efficiently by organs, in a manner different from that of DMDTAV. In addition, the distribution and metabolism of DMMTAV are like in manner similar to DMAIII in hamsters, while DMDTAV is in a manner similar to DMAV.",
Arsenic,1341650,"Lysobacter arseniciresistens sp. nov., an arsenite-resistant bacterium isolated from iron-mined soil Abstract: A Gram-negative, aerobic, motile, rod-shaped, arsenite [As(III)]-resistant bacterium, designated strain ZS79(T), was isolated from subsurface soil of an iron mine in China. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain ZS79(T) clustered closely with strains of five Lysobacter species, with 96.9, 96.1, 96.0, 95.8 and 95.3% sequence similarities to Lysobacter concretionis Ko07(T), L. daejeonensis GH1-9(T), L. defluvii IMMIB APB-9(T), L. spongiicola KMM 329(T) and L. ruishenii CTN-1(T), respectively. The major cellular fatty acids were iso-C(15:0) (28.6%), iso-C(17:1)?9c (19.9%), iso-C(16:0) (13.6%), iso-C(11:0) (12.6%) and iso-C(11:0) 3-OH (12.4%). The genomic DNA G+C content was 70.7 mol% and the major respiratory quinone was Q-8. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and an unknown phospholipid. On the basis of morphological and physiological/biochemical characteristics, phylogenetic position and chemotaxonomic data, this strain is considered to represent a novel species of the genus Lysobacter, for which the name Lysobacter arseniciresistens sp. nov. is proposed; the type strain is ZS79(T) (=CGMCC 1.10752(T)=KCTC 23365(T)).",
Arsenic,1519143,"Status of arsenic contamination in potable water of Northern areas of Mizoram State and its adjoining areas of Southern Assam, India Abstract: A reconnaissance survey was conducted to examine the physicochemical properties of the potable water of Northern parts of the State of Mizoram, India, as well as the adjoining southern parts of the State of Assam, India. Groundwater samples were taken from those sources of water which were used as potable water source in the area. All the samples were analyzed for ionic concentrations of potassium (K+), sodium (Na+), calcium (Ca2+), magnesium (Mg2+), chlorine (Cl?), sulfate (SO 4 2? ), manganese (Mn), iron (Fe), and arsenic (As). Parameters such as pH, electrical conductivity, total dissolved solids, and total hardness were also measured in situ using digital instruments. The aim of the present work is to study the various physicochemical parameters following the recommendations of World Health Organization in order to test whether these sources are safe enough to be used as potable water resources. Furthermore, present work will throw light on the probable causes of presence of arsenic in Silchar City of southern Assam and total absence of it in neighboring state of Mizoram.",
Arsenic,1797817,"Synthesis, Structure, and Properties of Two Zintl Phases around the Composition SrLiAs Abstract: Two atomic arrangements were found near the equiatomic composition in the strontium-lithium-arsenic system. Orthorhombic o-SrLiAs was synthesized by reaction of elemental components at 950 °C, followed by annealing at 800 °C and subsequent quenching in water. The hexagonal modification h-SrLi1-xAs was obtained from annealing of o-SrLiAs at 550 °C in dynamic vacuum. The structures of both phases were determined by single-crystal X-ray diffraction: o-SrLiAs, structure type TiNiSi, space group Pnma, Pearson symbol oP12, a = 7.6458(2) Å, b = 4.5158(1) Å, c = 8.0403(3) Å, V = 277.61(2) Å(3), RF = 0.028 for 558 reflections; h-SrLi1-xAs, structure type ZrBeSi, space group P63/mmc, Pearson symbol hP6, a = 4.49277(9) Å, c = 8.0970(3) Å, V = 141.54(1) Å(3), RF = 0.026 for 113 reflections. The analysis of the electron density within the framework of the quantum theory of atoms in molecules revealed a charge transfer according to the Sr(1.3+)Li(0.8+)As(2.1-), in agreement with the electronegativities of the individual elements. The electron localizability indicator distribution indicated the formation of a 3D anionic framework [LiAs] in o-SrLiAs and a rather 2D anionic framework [LiAs] in h-SrLi1-xAs. Magnetic susceptibility measurements point to a diamagnetic character of both phases, which verifies the calculated electronic density of states.",
Arsenic,1031036,"Management of health risks in the arsenic production industry: Modern production in Chile in the context of past experience in Britain Abstract: The hazards presented by arsenic are well known, and the notoriety gained by its use as a poison in previous years has affected attitudes towards the commercial production and employment of a very useful substance. It is not widely realized that Britain was the world's largest producer of arsenic around the turn of the century. Production has now ceased and any reserves that still exist will probably remain unexploited, despite the modern requirement for arsenic by the wood treatment and microelectronics industries. This demand is being satisfied by mines in other countries which use essentially the same refining process as that employed in England a century ago. This paper compares what is known about conditions of work and health in the English arsenic industry then with modern conditions at a Chilean production plant, and shows how the perception and management of the risks involved in a hazardous operation stems from the complex inter-relationship of technological, social, political and economic factors. In particular, the results of this survey explain why, in many previous surveys, a poor correlation was found between airborne and urinary arsenic measurements. Both measures appear to be strongly influenced by the particular type of work undertaken and this can be related to the chemical form of the arsenic present. Within each job category, the most important factor affecting their correlation is the difference in use of respiratory protection equipment.",
Arsenic,628424,"Unventilated indoor coal-fired stoves in Guizhou province, China: Cellular and genetic damage in villagers exposed to arsenic in food and air Abstract: BACKGROUND: Inorganic arsenic (iAs) is a well-known human carcinogen recognized by the World Health Organization and the International Agency for Research on Cancer. Currently, most iAs studies in populations are concerned with drinking water and occupational arsenicosis. In Guizhou province, arsenicosis caused by the burning of coal in unventilated indoor stoves is an unusual type of exposure. Because the poisoning mechanism involved in arsenicosis is as yet unknown and no effective therapy exists, progress has been slow on the prevention and therapy of arsenicosis. OBJECTIVES: We examined the relationship between arsenic (As) exposure from the burning of coal in unventilated indoor stoves and genetic damage in humans, using cellular and molecular indices. We selected villagers from Jiaole township, Guizhou province, China, who had been exposed to milligram levels of As daily via food and air contaminated by the burning of As-containing coal in unventilated indoor stoves. RESULTS: The As-exposed subjects from Jiaole were divided into four groups according to skin lesion symptoms: nonpatients, mild, intermediate, and severe arsenicosis. Another 53 villagers from a town 12 km from Jiaole were recruited as the external control group. In the four groups of exposed subjects, As concentrations in urine and hair were 76-145 microg/L and 5.4-7.9 microg/g, respectively. These values were higher than those in the external control group, which had As concentrations of 46 microg/L for urine and 1.6 microg/g for hair. We measured sister chromatid exchange and chromosomal aberrations to determine human chromosome damage, and for DNA damage, we measured DNA single-strand breaks and DNA-protein cross-links. All measurements were higher in the four exposed groups compared with the external control group. DNA repair was impaired by As exposure, as indicated by the mRNA of O-6-methylguanine-DNA methyltransferase (MGMT), X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1), and, to a lesser extent, by the mismatch repair gene hMSH2 mRNA. The expression of mutant-type p53 increased with aggravation of arsenicosis symptoms, whereas the expression of p16-INK4(p16) decreased. p53 mutated at a frequency of 30-17% in the carcinoma (n = 10) and precarcinoma (n = 12) groups. No mutation was found in p16, although deletion was evident. Deletion rates were 8.7% (n = 23) and 38.9% (n = 18) in noncarcinoma and carcinoma groups, respectively. CONCLUSIONS: The results showed that long-term As exposure may be associated with damage of chromosomes and DNA, gene mutations, gene deletions, and alterations of DNA synthesis and repair ability.",
Arsenic,2298721,"Arsenic disulfide induced apoptosis and concurrently promoted erythroid differentiation in cytokine-dependent myelodysplastic syndrome-progressed leukemia cell line F-36p with complex karyotype including monosomy 7 Abstract: <strong>OBJECTIVE: </strong>Acute myeloid leukemia progressed from myelodysplastic syndrome (MDS/AML) is generally incurable with poor prognosis for complex karyotype including monosomy 7 (-7). Qinghuang Powder (, QHP), which includes Qing Dai ( Indigo naturalis) and Xiong Huang (realgar) in the formula, is effective in treating MDS or MDS/AML even with the unfavorable karyotype, and its therapeutic efficacy could be enhanced by increasing the Xiong huang content in the formula, while Xiong huang contains &gt; 90% arsenic disulfide (As2S2). F-36p cell line was established from a MDS/AML patient with complex karyotype including -7, and was in cytokine-dependent. The present study was to investigate the effects of As2S2 on F-36p cells.<br /><br /><strong>METHODS: </strong>Cell proliferation was measured by an 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Cell apoptosis was identified by Annexin V-staining. Cell viability was determined by a propidium iodide (PI) exclusion. Erythroid differentiation was evaluated by the expression of cell surface antigen CD235a (GpA).<br /><br /><strong>RESULTS: </strong>After treatment with As2S2 at concentrations of 0.5 to 16 ?mol/L for 72 h, As2S2 inhibited the proliferation of F-36p cells. The 50% inhibitory concentrations (IC50) of As2S2 against the proliferation of F-36p cells was 6 ?mol/L. The apoptotic cells significantly increased in a dose-dependent mannar (P&lt;0.05). The cell viabilities were significantly inhibited by As2S2 dose-dependent in a dose-dependent manner (P&lt;0.05). Significant increases of CD235a-positive cells were concurrently observed (P&lt;0.05) also in a dosedependent manner.<br /><br /><strong>CONCLUSIONS: </strong>As2S2 could inhibit proliferation and viability, induce apoptosis, and concurrently promote erythroid differentiation dose-dependently in F-36p cells. As2S2 can inhibit proliferation and viability, induce apoptosis, and concurrently promote erythroid differentiation in cytokine-dependent MDS-progressed human leukemia cell line F-36p with complex karyotype including -7. The data suggest that QHP and/or As2S2 could be a potential candidate in the treatment of MDS or MDS/AML even with unfavorable cytogenetics.",
Arsenic,627869,"Higher prevalence of goiter in endemic area of blackfoot disease of Taiwan Abstract: Blackfoot disease is an endemic peripheral vascular disorder which is confined to a limited land area on the southwest coast of Taiwan. It has long been related to the consumption of high levels of arsenic found in the artesian well water. Humic substances have also been extracted from the well water and have been reported as a possible source of environmental goitrogen. The purpose of this study was to examine whether the prevalence of goiter is increased in the blackfoot disease-endemic area. This study covered all the children in the elementary schools of Putai and Peimen. They were divided into two groups according to the location of schools in the endemic area or non-endemic area of blackfoot disease. Thyroid enlargement was examined by palpation as recommended by the World Health Organization. Thyroid antibodies and hormones were determined in school children with a goiter and age-sex-matched normal control children using particle agglutination methods and radioimmunoassays, respectively. Aspiration cytology was done in cases with a nodular goiter. In total 4,567 school children were examined, including 2,306 males and 2,261 females. One hundred and twenty school children (2.63%) had a goiter of grade I or above. The prevalence of goiters in school children from the endemic area was higher than that from the non-endemic area (3.44 vs 2.08%, p less than 0.01). The prevalence of goiters in females from the endemic area was higher than that from the non-endemic area (4.65 vs 2.69%, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,628546,"Diabetes mellitus and arsenic exposure: A second look at case-control data from a Swedish copper smelter Abstract: OBJECTIVES--To find out whether a newly found association between diabetes mellitus and arsenic in drinking water in Taiwan could be reproduced in copper smelters with arsenic exposure. METHODS--Extended analysis of a previous case-control study from 1978 was based on death records and objective exposure information from the company. The final analysis included only those employed at the smelter. Cases were 12 people with diabetes mellitus on the death certificate and those for whom there was clinical information on this disease. Controls were 31 people without cancer, cardiovascular and cerebrovascular disease as these disease categories had been associated with arsenic exposure in the original study and elsewhere. RESULTS--The odds ratios found for diabetes mellitus with increasing arsenic exposure categories were (reference level = 1), 2.0, 4.2, and 7.0, but the 95% confidence intervals included unity. Unstratified test for trend was weakly significant, P = 0.03. CONCLUSIONS--Although based on small numbers, the findings provide some support for the suggestion that arsenic exposure could sometimes play a part in the development of diabetes mellitus.",
Arsenic,627845,"Excretion of arsenic in urine as a function of exposure to arsenic in drinking water Abstract: Urinary arsenic (As) concentrations were evaluated as a biomarker of exposure in a U.S. population chronically exposed to inorganic As (InAs) in their drinking water. Ninety-six individuals who consumed drinking water with As concentrations of 8-620 microg/L provided first morning urine voids for up to 5 consecutive days. The study population was 56% male, and 44% was younger than 18 years of age. On one day of the study period, all voided urines were collected over a 24-hr period. Arsenic intake from drinking water was estimated from daily food diaries. Comparison between the concentration of As in individual urine voids with that in the 24-hr urine collection indicated that the concentration of As in urine was stable throughout the day. Comparison of the concentration of As in each first morning urine void over the 5-day study period indicated that there was little day-to-day variation in the concentration of As in urine. The concentration of As in drinking water was a better predictor of the concentration of As in urine than was the estimated intake of As from drinking water. The concentration of As in urine did not vary by gender. An age-dependent difference in the concentration of As in urine may be attributed to the higher As dosage rate per unit body weight in children than in adults. These findings suggest that the analysis of a small number of urine samples may be adequate to estimate an individual's exposure to InAs from drinking water and that the determination of the concentration of InAs in a drinking water supply may be a useful surrogate for estimating exposure to this metalloid.",
Arsenic,2278501,"Determination of arsenic in drinking water samples by electrothermal atomic absorption spectrometry after preconcentration using the biomass of Aspergillus niger loaded on activated charcoal Abstract: A simple, fast, and sensitive method for determination of total arsenic in drinking water sample by ETAAS after solid phase preconcentration has been developed. The dead biomass of A. niger loaded on activated charcoal has been applied as bioadsorbent for preconcentration step. The effects of parameters such as pH, type and concentration of eluent, biosorption time, sample volume, and effect of interfering ions have also been studied. Under the optimum condition, the enrichment factor of 10 for the analyte has been obtained. The accuracy of the method has been investigated by the recovery of spiked standards and the recovery percents between 99 and 102% have been achieved. Total amount of arsenic was determined by reducing As (V) to As (III) with potassium iodide (KI) and ascorbic acid in HCl solution. Under the optimum conditions, for 400?mL of drinking water samples, the detection limit (3?) and linear range were achieved 1?ng/mL and 5–100?ng/mL, respectively. The relative standard deviation for ten determinations of a spiked sample with concentration of 10?ng/mL As was 3.2%.",
Arsenic,656904,"Effects of inorganic arsenic on the rat and mouse urinary bladder Abstract: Inorganic arsenic (arsenate and arsenite) is a known human carcinogen, inducing tumors of the skin, urinary bladder, and lung. Understanding the mechanism of inorganic arsenic carcinogenesis has been hampered by a lack of animal models. To define the urothelial effects of inorganic arsenic, we administered arsenate and arsenite in the diet or drinking water to rats and mice in several short-term experiments (2-10 weeks). Treatment with arsenate or arsenite in the drinking water or diet induced cytotoxicity and necrosis of the urothelial superficial layer and hyperplasia in rats and mice. Arsenate-induced changes occurred later in mice compared with arsenite-induced changes, but not in the rat. Hyperplasia in rats was evident by light microscopy at an earlier time point (2 weeks) than previously observed after treatment with dimethylarsinic acid (DMA(V)). The bromodeoxyuridine labeling index was increased in treated rats. We were unable to determine the bromodeoxyuridine labeling index in mice. The effects of inorganic arsenicals on the bladder were greater when administered in the drinking water than in the diet in rats and mice, but so was the overall toxicity to the animal. The female rat appeared more sensitive to the effects of inorganic arsenic than the male rat, but effects were similar in female and male mice. The mode of action of inorganic arsenic in rats and mice appears to involve urothelial cytotoxicity, increased cell proliferation and ultimately tumors. Cytotoxicity is likely due to the generation of reactive trivalent arsenicals excreted in the urine.",
Arsenic,1519074,"Metabolites associated with adaptation of microorganisms to an acidophilic, metal-rich environment identified by stable-isotope-enabled metabolomics Abstract: Microorganisms grow under a remarkable range of extreme conditions. Environmental transcriptomic and proteomic studies have highlighted metabolic pathways active in extremophilic communities. However, metabolites directly linked to their physiology are less well defined because metabolomics methods lag behind other omics technologies due to a wide range of experimental complexities often associated with the environmental matrix. We identified key metabolites associated with acidophilic and metal-tolerant microorganisms using stable isotope labeling coupled with untargeted, high-resolution mass spectrometry. We observed &gt;3,500 metabolic features in biofilms growing in pH ~0.9 acid mine drainage solutions containing millimolar concentrations of iron, sulfate, zinc, copper, and arsenic. Stable isotope labeling improved chemical formula prediction by &gt;50% for larger metabolites (&gt;250 atomic mass units), many of which were unrepresented in metabolic databases and may represent novel compounds. Taurine and hydroxyectoine were identified and likely provide protection from osmotic stress in the biofilms. Community genomic, transcriptomic, and proteomic data implicate fungi in taurine metabolism. Leptospirillum group II bacteria decrease production of ectoine and hydroxyectoine as biofilms mature, suggesting that biofilm structure provides some resistance to high metal and proton concentrations. The combination of taurine, ectoine, and hydroxyectoine may also constitute a sulfur, nitrogen, and carbon currency in the communities. IMPORTANCE Microbial communities are central to many critical global processes and yet remain enigmatic largely due to their complex and distributed metabolic interactions. Metabolomics has the possibility of providing mechanistic insights into the function and ecology of microbial communities. However, our limited knowledge of microbial metabolites, the difficulty of identifying metabolites from complex samples, and the inability to link metabolites directly to community members have proven to be major limitations in developing advances in systems interactions. Here, we show that combining stable-isotope-enabled metabolomics with genomics, transcriptomics, and proteomics can illuminate the ecology of microorganisms at the community scale.",
Arsenic,1337590,"Hijacking membrane transporters for arsenic phytoextraction Abstract: Arsenic is a toxic metalloid and recognized carcinogen. Arsenate and arsenite are the most common arsenic species available for uptake by plants. As an inorganic phosphate (Pi) analog, arsenate is acquired by plant roots through endogenous Pi transport systems. Inside the cell, arsenate is reduced to the thiol-reactive form arsenite. Glutathione (GSH)-conjugates of arsenite may be extruded from the cell or sequestered in vacuoles by members of the ATP-binding cassette (ABC) family of transporters. In the present study we sought to enhance both plant arsenic uptake through Pi transporter overexpression, and plant arsenic tolerance through ABC transporter overexpression. We demonstrate that Arabidopsis thaliana plants overexpressing the high-affinity Pi transporter family members, AtPht1;1 or AtPht1;7, are hypersensitive to arsenate due to increased arsenate uptake. These plants do not exhibit increased sensitivity to arsenite. Co-overexpression of the yeast ABC transporter YCF1 in combination with AtPht1;1 or AtPht1;7 suppresses the arsenate-sensitive phenotype while further enhancing arsenic uptake. Taken together, our results support an arsenic transport mechanism in which arsenate uptake is increased through Pi transporter overexpression, and arsenic tolerance is enhanced through YCF1-mediated vacuolar sequestration. This work substantiates the viability of coupling enhanced uptake and vacuolar sequestration as a means for developing a prototypical engineered arsenic hyperaccumulator.",
Arsenic,2149254,"A critical review of the arsenic uptake mechanisms and phytoremediation potential of Pteris vittata Abstract: The discovery of the arsenic hyperaccumulator, Pteris vittata (Chinese brake fern), has contributed to the promotion of its application as a means of phytoremediation for arsenic removal from contaminated soils and water. Understanding the mechanisms involved in arsenic tolerance and accumulation of this plant provides valuable tools to improve the phytoremediation efficiency. In this review, the current knowledge about the physiological and molecular mechanisms of arsenic tolerance and accumulation in P. vittata is summarized, and an attempt has been made to clarify some of the unresolved questions related to these mechanisms. In addition, the capacity of P. vittata for remediation of arsenic-contaminated soils is evaluated under field conditions for the first time, and possible solutions to improve the remediation capacity of Pteris vittata are also discussed.",
Arsenic,193553,"Micronuclei in exfoliated bladder cells among individuals chronically exposed to arsenic in drinking water Abstract: Inorganic arsenic is an established cause of lung and skin cancer. Epidemiological evidence from Taiwan suggests that arsenic causes more fatal internal cancers, with the highest relative risks reported for bladder cancer. We conducted a cross-sectional biomarker study in a Chilean male population chronically exposed to high (70 subjects) and low (55 subjects) arsenic levels in their drinking water (average concentrations, 600 and 15 micrograms As/liter, respectively). A fluorescent version of the exfoliated bladder cell micronucleus (MN) assay was used employing fluorescence in situ hybridization with a centromeric probe to identify the presence (MN+) or absence (MN-) of whole chromosomes within micronuclei, thereby determining the mechanism of arsenic-induced genotoxicity in vivo. We divided the study population into quintiles by urinary arsenic levels and found an exposure-dependent increase in micronucleated cell prevalence in quintiles 2-4 (urinary arsenic, 54-729 micrograms/liter). The largest increase appeared when quintile 4 was compared to quintile 1 [prevalence ratio, 3.0; 95% confidence interval (CI), 1.9-4.6]. The prevalence of MN+ increased to 3.1-fold in quintile 4 (95% CI, 1.4-6.6), and the prevalence of MN-increased to 7.5-fold in quintile 3 (95% CI, 2.8-20.3), suggesting that chromosome breakage was the major cause of MN formation. Prevalences of total MN, MN+, and MN- returned to baseline levels in quintile 5 (urinary arsenic, 729-1894 micrograms/liter), perhaps due to cytostasis or cytotoxicity. These results add additional weight to the hypothesis that ingesting arsenic-contaminated water enhances bladder cancer risk and suggest that arsenic induces genetic damage to bladder cells at drinking water levels close to the current United States Maximum Contaminant Level of 50 micrograms/liter for arsenic.",
Arsenic,1032321,Selenium-responsive disease of sheep Abstract: ,
Arsenic,1021184,"Environmental risk factors predisposing to the development of basal cell carcinoma Abstract: <strong>BACKGROUND: </strong>Basal cell carcinomas (BCCs) are the most common malignancies in white people. The incidence varies depending on the region of the world, with the highest rate of 1% to 2% per year noted in Australia. It is estimated that BCC incidence increases by 5% annually. An increasing incidence of BCC is in line with the changes in the living style and exposure to various environmental factors.<br /><br /><strong>OBJECTIVE: </strong>To present the environmental factors that may influence the development of BCCs. The influence of ultraviolet radiation exposure alone and in connection with immunosuppression, smoking, occupational factors, as well as arsenic and ionizing radiation exposure, was described.<br /><br /><strong>CONCLUSION: </strong>BCC is a very complex disease, with many factors influencing its development. Environmental factors are very important for the prevalence of BCC, and most of them can be avoided. The exposure to ultraviolet radiation is undoubtedly of great risk; therefore, the national campaigns against aggressive, seasonal sun exposure, especially in children and adolescents, as well as using sunscreens, are of great value in the fight against BCC development.",
Arsenic,656642,"In vitro tissue specificity for arsine and arsenite toxicity in the rat Abstract: The mechanism of arsine (AsH3) toxicity is not completely understood. In this investigation, we determined AsH3 and arsenite (AsIII) toxicity in Sprague Dawley rat blood, liver, and kidney. In all systems, there were dose- and time-dependent responses. Red blood cells were very susceptible to AsH3 toxicity. This was demonstrated by an immediate intracellular potassium loss and by hemolysis and lactate dehydrogenase (LDH) leakage that occurred by one h. AsIII concentrations up to 1 mM were not toxic to red blood cells using these indicators. Both AsH3 and AsIII produced toxicity in primary hepatocytes. Both produced significant LDH leakage and decreases in intracellular K+ by 5 h, but AsIII was more toxic than AsH3. At 24 h, both arsenic species showed similar toxicity. In renal cortical epithelial cells, AsH3 produced no effects on LDH and K+ over a 5-h period but produced significant LDH leakage by 24 h. In these cells, AsIII produced significant toxicity as early as in 3 h. These results showed that unchanged AsH3 produced toxicity in tissues, in addition to blood, and that toxicity of arsenicals is arsenic species- and tissue-dependent.",
Arsenic,1677620,"Air dispersion of heavy metals in the vicinity of the As-Sb-Tl abounded mine and responsiveness of moss as a biomonitoring media in small-scale investigations Abstract: A systematic study was carried out to investigate air deposition and to explore the natural distribution and enrichment (contamination) with trace elements in the small area (cca. 13 km(2)) of an antimony-arsenic-thallium mineralization outcrop at an abandoned mine Allchar. The mine is located on the northwestern part of Kožuf Mount, Republic of Macedonia. The locality of Allchar is unique in its mineral composition; besides a very intriguing mineral, lorandite, there are 45 other minerals, some of which are rare. The distribution of 53 elements (with special attention to As, Sb, and Tl) were detected in 69 moss samples from eight various species collected from this area. Moss samples were analyzed following microwave digestion by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry. It was found that the atmospheric deposition for As in the moss samples on or around the Allchar mine is >6.5 times higher and for Tl is 19 times higher compared to values for the samples from the rest of the Allchar area. By the application of multivariate cluster and R-mode factor analyses (FA), five geochemical associations were determined. Cluster and R-mode FA were used to identify and characterize element associations, and five associations of elements were determined by the method of multivariate statistics. F1 (Co, Cr, Fe, Sc, Li, V, Ga, Y, Ni, Mn, Al, La-Lu, Cu, Ge, Be, Bi, and Hf); F2 (As, Tl, Sb, and Mg); F3 (Rb, Cs, and Mo); F4 (Sr, Ba, Hf, Zr, La-Lu, and Bi), and F5 (Cd, Zn, Ag, and Cu).",
Arsenic,1508535,"Effects of nutrient and lime additions in mine site rehabilitation strategies on the accumulation of antimony and arsenic by native Australian plants Abstract: The effects of nutrient and lime additions on antimony (Sb) and arsenic (As) accumulation by native Australian and naturalised plants growing in two contaminated mine site soils (2735mgkg(-1) and 4517mgkg(-1) Sb; 826mgkg(-1) and 1606 As mgkg(-1)) was investigated using a glasshouse pot experiment. The results indicated an increase in soil solution concentrations with nutrient addition in both soils and also with nutrient+lime addition for Sb in one soil. Metalloid concentrations in plant roots were significantly greater than concentrations in above ground plant parts. The metalloid transfer to above ground plant parts from the roots and from the soil was, however, low (ratio of leaf concentration/soil concentration?1) for all species studied. Eucalyptus michaeliana was the most successful at colonisation with lowest metalloid transfer to above ground plant parts. Addition of nutrients and nutrients+lime to soils, in general, increased plant metalloid accumulation. Relative As accumulation was greater than that of Sb. All the plant species studied were suitable for consideration in the mine soil phytostabilisation strategies but lime additions should be limited and longer term trials also recommended.",
Arsenic,8741,"Comparative pulmonary toxicity of gallium arsenide, gallium(III) oxide, or arsenic(III) oxide intratracheally instilled into rats Abstract: The relative toxicity of gallium arsenide (GaAs) and its metal oxides was assessed by intratracheally instilling particulate suspensions of GaAs (100 mg/kg), equimolar gallium as Ga2O3 (65 mg/kg), or a maximally tolerated nonlethal dose of arsenic as As2O3 (17 mg/kg). Two weeks after dosing, five rats from each group were randomly selected for the biochemical determination of lung lipid, protein, DNA, and collagen (4-hydroxyproline; 4-HP) content. The pulmonary retention of gallium and/or arsenic and the concentration of these metals in blood were also determined. Lungs from the remaining rats (n = 3) were examined histopathologically. Pulmonary exposure to Ga2O3 particulates significantly (p less than 0.05) increased the total lipid content of lungs relative to that observed in the vehicle-treated control animals. This response appeared to be associated with the pulmonary retention of gallium particulates (means = 36% of the gallium dose). In contrast, As2O3 particulates were not retained in the lung. Blood arsenic concentrations were 36 ppm which represented 20% of the total arsenic administered. Treatment with As2O3 significantly elevated lung dry weight as well as protein, DNA, and 4-HP content. These data suggest that As2O3 induced an acute fibrogenic response. The intratracheal instillation of GaAs particulates produced effects similar to those observed with the individual oxides. The total lung content of lipids, protein, and DNA was significantly elevated. These biochemical changes were accompanied by significant increases in lung dry weight and lung wet weight. Lungs from rats receiving GaAs particulates retained 44% of the dose as gallium and 28% of the dose as arsenic at the end of the 14-day study. Blood arsenic concentrations were 44 ppm (7% of the arsenic dose) while gallium was not detected in blood at this time. The primary histopathological observations 14 days after the intratracheal instillation of all metal particulates were an inflammatory response and pneumonocyte hyperplasia. The biological severity of these lesions, in descending order, was GaAs greater than As2O3 much greater than Ga2O3. It must be noted, however, that As2O3 was dosed at 0.25 X moles of GaAs.",
Arsenic,1028644,"ARS5 is a component of the 26S proteasome complex, and negatively regulates thiol biosynthesis and arsenic tolerance in Arabidopsis Abstract: A forward-genetic screen in Arabidopsis led to the isolation of several arsenic tolerance mutants. ars5 was the strongest arsenate- and arsenite-resistant mutant identified in this genetic screen. Here, we report the characterization and cloning of the ars5 mutant gene. ars5 is shown to exhibit an increased accumulation of arsenic and thiol compounds during arsenic stress. Rough mapping together with microarray-based expression mapping identified the ars5 mutation in the alpha subunit F (PAF1) of the 26S proteasome complex. Characterization of an independent paf1 T-DNA insertion allele and complementation by PAF1 confirmed that paf1 mutation is responsible for the enhanced thiol accumulation and arsenic tolerance phenotypes. Arsenic tolerance was not observed in a knock-out mutant of the highly homologous PAF2 gene. However, genetic complementation of ars5 by the overexpression of PAF2 suggests that the PAF2 protein is functionally equivalent to PAF1 when expressed at high levels. No detectible difference was observed in total ubiquitinylated protein profiles between ars5 and wild-type (WT) Arabidopsis, suggesting that the arsenic tolerance observed in ars5 is not derived from a general impairment in proteasome-mediated protein degradation. Quantitative RT-PCR showed that arsenic induces the enhanced transcriptional activation of several key genes that function in glutathione and phytochelatin biosynthesis in the WT, and this arsenic induction of gene expression is more dramatic in ars5. The enhanced transcriptional response to arsenic and the increased accumulation of thiol compounds in ars5, compared with WT, suggest the presence of a positive regulation pathway for thiol biosynthesis that is enhanced in the ars5 background.",
Arsenic,1347663,Effects of treatment with arsenite on the cytotoxicity of r-ray-irradiated Chinese hamster ovary cells and human fibroblasts Abstract: ,
Arsenic,1019520,"Arsenite induces apoptosis via a direct effect on the mitochondrial permeability transition pore Abstract: The molecular mode of action of arsenic, a therapeutic agent employed in the treatment of acute promyelocytic leukemia, has been elusive. Here we provide evidence that arsenic compounds may act on mitochondria to induce apoptosis. Arsenite induces apoptosis accompanied by a loss of the mitochondrial transmembrane potential (Delta Psim). Inhibition of caspases prevents the arsenite-induced nuclear DNA loss, but has no effect on the Delta Psim dissipation and cytolysis induced by arsenite. In contrast, Bcl-2 expression induced by gene transfer prevents all hallmarks of arsenite-induced cell death, including the Delta Psim collapse. PK11195, a ligand of the mitochondrial benzodiazepine receptor, neutralizes this Bcl-2 effect. Mitochondria are required in a cell-free system to mediate arsenite-induced nuclear apoptosis. Arsenite causes the release of an apoptosis-inducing factor (AIF) from the mitochondrial intermembrane space. This effect is prevented by the permeability transition (PT) pore inhibitor cyclosporin A, as well as by Bcl-2, which is known to function as an endogenous PT pore antagonist. Arsenite also opens the purified, reconstituted PT pore in vitro in a cyclosporin A- and Bcl-2-inhibitible fashion. Altogether these data suggest that arsenite can induce apoptosis via a direct effect on the mitochondrial PT pore.",
Arsenic,2345627,"Heavy metal pollution in vegetables grown in the vicinity of a multi-metal mining area in Gejiu, China: Total concentrations, speciation analysis, and health risk Abstract: A field survey was conducted to investigate the present situation and health risk of arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in soils and vegetables in a multi-metal mining area, Gejiu, China. Furthermore, three vegetables (water spinach, potato, and summer squash) containing high metal concentrations were selected to further analyze metal speciation. The results showed that the average concentrations of five metals in soil exceeded the limiting values, and their bioavailable concentrations were significantly positively correlated to the total ones. Heavy metals in the edible parts of vegetables also exceeded the corresponding standards. The leaves of pakchoi, peppermint, and coriander had a strong metal-accumulative ability and they were not suitable for planting. Except the residue forms, the main forms of metals in the edible parts of three selected vegetables were ethanol-, NaCl-, and HAc-extractable fractions for As, Pb, and Cd, respectively; however, Cu was mainly presented as NaCl-extractable and Zn as HAc-extractable fractions. A high proportion of ethanol-extractable As showed that As bioactivity and toxic effects were the highest. Although the total and bioavailable Cd were high in soil, its speciation in vegetables was mainly presented as HAc-extractable fraction, which has a relatively low bioactivity. Lead and arsenic were imposing a serious threat on the local residents via vegetable consumption.",
Arsenic,2149371,"The use of granular iron-based sorption materials for nickel removal from water Abstract: Removal of nickel from water using granular iron-based adsorption materials Bayoxide E33, CFH12, CFH18, and GEH, and the comparison of their efficiency at different pH values was investigated. The results proved that the iron-based sorption materials have a capacity to reduce the content of nickel in water to values that meet the requirements set under the Regulation of the Government of the Slovak Republic No. 496/2010 on drinking water (20 ?g/L Ni). This maximum contaminant limit (MCL) complies with the recommendations of WHO, the US EPA, and EU Directive 2008/105/EC. Based on the pilot column tests, the most suitable adsorbent for nickel removal is Bayoxide E33. However, its effectiveness increases with decreasing water pH. For this material it is better to treat the water at lower pH, i.e. 6.5 to 7.5. According to the model tests (concentration of nickel in raw water of about 50 ?g/L, filtration rate 5.8 m/hour, concentration Ni 20 ?g/L at the outlet of media with the height of 58 cm, pH 7.0), the adsorption capacity of nickel for Bayoxide E33 was set to 198 ?g/g and ratio V/V0 = 4808. The results proved that the materials CFH12, CFH18 and GEH can also be used to decrease the concentration of Ni in drinking water below the limit value. The pH value of water affects the efficiency of nickel removal. In the case of CFH12 the best results were obtained at pH 7. The highest efficiency of GEH was reached in water pH above 7.5. The adsorption capacities and V/V0 ratio are lower for these sorption materials. Chemical composition of used sorption materials was determined.",
Arsenic,710842,"Arsenic species, AS3MT amount, and AS3MT gene expression in different brain regions of mouse exposed to arsenite Abstract: Human exposure to inorganic arsenic (iAs) has been associated with cancer and serious injury to various internal organs, as well as peripheral neuropathy, endocrine disruption and diverse effects in the central nervous system (CNS). Using rodent models, it is possible to demonstrate As accumulation in the brain that leads to defects in operant learning, behavioral changes, and affect pituitary gonadotrophins. iAs biomethylation in the CNS is a significant process, yielding products that are more reactive and toxic than the parent compound. Mice received 2.5, 5, and 10 mg/kg/day sodium arsenite orally for 9 days. We investigated the distribution of iAs and its metabolites as well as the mRNA and protein expression of arsenic (III) methyltransferase (AS3MT), which encodes the key enzyme in iAs metabolism, in the cerebral cortex, hippocampus, striatum, mesencephalon, thalamus, cerebellum, hypothalamus, pons, medulla oblongata, and pituitary of mouse brain. Our findings show that methylated As metabolites are present in all brain regions studied suggesting that AS3MT is ubiquitously expressed in the brain and it is not inducible by dose of arsenite. There is also a dose-related accumulation of As species in all brain regions, with the highest accumulation observed in the pituitary. The higher distribution of arsenicals in pituitary can help to explain the neuroendocrine effects associated with iAs exposure.",
Arsenic,1252369,"Chronic arsenic poisoning and respiratory effects in Bangladesh Abstract: A large population in Bangladesh have been exposed to naturally occurring inorganic arsenic through their drinking water. A prevalence comparison study of respiratory disorders among subjects with and without arsenic exposure through drinking water was conducted in Bangladesh. Characteristic skin lesions, keratoses and pigmentation alteration, and the water arsenic level confirmed the arsenic exposure. Three villages were selected from health awareness campaign programs. Participants in these courtyard meetings who had suspected skin lesions. i.e., keratosis, hyperpigmentation and hypopigmentation, were examined by a well-trained medical officer to confirm the diagnosis. Unexposed subjects were randomly selected from another village, where tubewells were not contaminated with arsenic. We interviewed and examined 218 individuals irrespective of age and sex from these villages. The arsenic level in their drinking water was measured and the mean arsenic level was 614 mug/l (ranging from 136 mug/l to 1,000 mug/l). Information regarding respiratory system signs and symptoms was also collected. There were few smokers, and analyses were therefore confined to nonsmokers. The overall crude prevalence (or risk) among the exposed subjects for chronic cough, and chronic bronchitis, was three times the prevalence in the control population. Age was a slightly negative confounding factor. The crude prevalence ratios were noticeably increased for female participants compared to male participants. A possible explanation for this noticeably increased occurrence of respiratory signs and symptoms in women is related to the presence of weakness. These results add to the evidence that long-term ingestion of arsenic can cause respiratory problems especially among females.",
Arsenic,1022245,"Differential effects of arsenic on intracellular free calcium levels and the proliferative response of murine mitogen-stimulated lymphocytes Abstract: This study examined the effects of sodium arsenite treatment on free [Ca(2+)]i and cell death in mitogen-activated murine lymphocytes. The main findings of this study were that simultaneous sodium arsenite treatment inhibited PHA- but not Con A-induced T cell proliferation, induced a higher increase in free [Ca(2+)]i and an early increase in the proportion of dead cells in PHA than in Con A activated cells. Sodium arsenite pre-treatment reduced both PHA- and Con A-induced T-cell proliferation. Phorbol myristate ester (PMA) did not prevent the inhibitory effects of both sodium arsenite treatments, suggesting that sodium arsenite did not significantly decreased PKC activation or that its effects occurred on events parallel to PKC activation. Both PHA and Con A increased free [Ca(2+)]i after stimulation, yet the effect was more pronounced in mitogen-activated cells simultaneously treated with sodium arsenite and particularly in those activated with PHA. The increase in free [Ca(2+)]i was in agreement with the early cell death induced by sodium arsenite in PHA-activated cells, a finding consistent with the inhibitory effects on PHA-induced proliferation. Sodium arsenite-induced cell death occurred faster in PHA-activated cells. Further studies are needed to ascertain the relationships between the effects of sodium arsenite on free [Ca(2+)]i levels and the type of cell death induced by sodium arsenite and their relevance for the proliferative response of T cells.",
Arsenic,734937,"Effects of arsenic exposure on DNA methylation and epigenetic gene regulation Abstract: Arsenic is a nonmutagenic human carcinogen that induces tumors through unknown mechanisms. A growing body of evidence suggests that its carcinogenicity results from epigenetic changes, particularly in DNA methylation. Changes in gene methylation status, mediated by arsenic, have been proposed to activate oncogene expression or silence tumor suppressor genes, leading to long-term changes in the activity of genes controlling cell transformation. Mostly descriptive, and often contradictory, studies have demonstrated that arsenic exposure is associated with both hypo- and hyper-methylation at various genetic loci in vivo or in vitro. This ambiguity has made it difficult to assess whether the changes induced by arsenic are causally involved in the transformation process or are simply a reflection of the altered physiology of rapidly dividing cancer cells. Here, we discuss the evidence supporting changes in DNA methylation as a cause of arsenic carcinogenesis and highlight the strengths and limitations of these studies, as well as areas where consistencies and inconsistencies exist.",
Arsenic,627980,"Liver tumorigenicity of trimethylarsine oxide in male Fischer 344 rats--association with oxidative DNA damage and enhanced cell proliferation Abstract: Arsenic is a notorious environmental toxicant known to be carcinogenic for the skin, lung and urinary bladder in human beings. The carcinogenicity of trimethylarsine oxide (TMAO), one organic metabolite of inorganic arsenics in humans and experimental animals, was investigated here in male Fischer 344 rats in a 2-year carcinogenicity test. TMAO was administered to a total of 129 male rats ad libitum at concentrations of 0 (Control), 50 or 200 p.p.m. in the drinking water. In animals that died or were killed from the 87th week until the end of 104th week, incidences of hepatocellular adenomas were 14.3, 23.8 and 35.6% in the 0, 50 and 200 p.p.m.-treated groups, respectively; the multiplicities were 0.21, 0.33 and 0.53. Both were significantly increased in the 200 p.p.m.-treated group. While a variety of other tumors developed in various organs, they were present in all groups, including the controls, and were histologically diagnosed as those known to occur spontaneously in F344 rats. To test the contribution of reactive oxygen species (ROS) to TMAO tumorigenicity in the liver, 8-hydroxydeoxyguanosine (8-OHdG) formation was assessed by high performance liquid chromatography. The 8-OHdG values for the 200 p.p.m. TMAO group were significantly higher than those for the control group. Furthermore, as assessed by the proliferating cell nuclear antigen index, cell proliferation in the normally appearing parenchyma was elevated by the TMAO treatment. These results indicate that TMAO exerts liver tumorigenicity with possible mechanistic roles for oxidative DNA damage and enhanced cell proliferation.",
Arsenic,1346378,"Arsenite induces HIF-1alpha and VEGF through PI3K, Akt and reactive oxygen species in DU145 human prostate carcinoma cells Abstract: Arsenite is widely distributed environmental toxicant in water, food and air. It is a known human carcinogen, which is strongly associated with human cancers originated from liver, nasal cavity, lung, skin, bladder, kidney, and prostate. In this study, we investigated whether arsenite induces expression of hypoxia-inducible factor 1 (HIF-1). HIF-1 is a heterodimeric basic helix-loop-helix transcription factor, composed of HIF-1alpha and HIF-1beta/ARNT subunits; and is involved in tumor growth and angiogenesis. Here we demonstrate that arsenite induces the expression of HIF-1alpha but not HIF-1beta subunit in DU145 human prostate carcinoma cells. Arsenite also increases the expression of VEGF through the induction of HIF-1. We also found that arsenite activates PI3K and Akt that are required for arsenite-induced expression of HIF-1alpha and VEGF. The induction of HIF-1 and VEGF by arsenite can not be inhibited by MAP kinase inhibitors. Arsenite causes production of reactive oxygen species (ROS). The major species of ROS required for the induction of HIF-1 and VEGF is H2O2. These data indicate that the arsenite-induced activation of PI3K/Akt signaling and the expression of HIF-1 and VEGF through the generation of ROS could be an important mechanism in the arsenite-induced carcinogenesis.",
Arsenic,626992,"Pulmonary involvement in chronic arsenic poisoning from drinking contaminated ground-water Abstract: OBJECTIVES: Chronic arsenic poisoning, due to ingestion of contaminated ground-water, is a major public health problem in West Bengal. It causes multiorgan damage. The present study attempts to objectively investigate the pulmonary involvement by examining the lung function. The nature of lung changes was also evaluated. MATERIAL AND METHODS: One hundred and seven subjects with (cases) and 52 subjects without (controls) chronic arsenic poisoning were examined by spirometry. Forced expiratory volume-I second (FEVI), forced vital capacity (FVC) and peak expiratory flow rate (PEFR) were measured. Bronchoalveolar lavage (BAL) was performed in five cases with and five cases without pulmonary involvement. RESULTS: Thirty three (30.8%) cases and four (7.6%) controls (p<0.01) had respiratory involvement. The pattern of involvement in cases was: obstructive- 20(68.9%) (including three (10%) with bronchiectasis), restrictive- 1(3.5%), mixed- 8(27.6%), malignancy- 4(12.1%) (adenocarcinoma-I, squamous cell- 2, undifferentiated- I). FEVI (69.7+/-25.9 [n=105] vs 83.7+/-15.19 [n=51], p=0.0005), FVC (77.4+/-22.7 [n=105] vs 85.6+/-18.23 [n=51], p=0.025), FEVI/FVC (73.6+/-13.38 [n=105] vs 79.1+/-18.65 [n=52], p=0.007) and PEFR (53.9+/-21.52 [n= 103] vs 67.3+/-18.36 [n=51], p=0.0002) (percent of predicted) were all reduced more in cases compared to controls. Worsening of these parameters correlated with increasing degree of arsenic toxicity. Markers of inflammation (macrophage, lactate dehydrogenase, nitric oxide) were apparently more in the BAL fluid of those with lung involvement than in those without, though the arsenic content did not differ significantly. CONCLUSION: Chronic arsenic poisoning causes pulmonary involvement, predominantly obstructive, the degree of which worsens with increasing degree of arsenic toxicity. Inflammation, rather than direct toxicity, appears to be the underlying mechanism.",
Arsenic,2088465,"JNK and NADPH oxidase involved in fluoride-induced oxidative stress in BV-2 microglia cells Abstract: Excessive fluoride may cause central nervous system (CNS) dysfunction, and oxidative stress is a recognized mode of action of fluoride toxicity. In CNS, activated microglial cells can release more reactive oxygen species (ROS), and NADPH oxidase (NOX) is the major enzyme for the production of extracellular superoxide in microglia. ROS have been characterized as an important secondary messenger and modulator for various mammalian intracellular signaling pathways, including the MAPK pathways. In this study we examined ROS production and TNF- ? , IL-1 ? inflammatory cytokines releasing, and the expression of MAPKs in BV-2 microglia cells treated with fluoride. We found that fluoride increased JNK phosphorylation level of BV-2 cells and pretreatment with JNK inhibitor SP600125 markedly reduced the levels of intracellular O?(·-) and NO. NOX inhibitor apocynin and iNOS inhibitor SMT dramatically decreased NaF-induced ROS and NO generations, respectively. Antioxidant melatonin (MEL) resulted in a reduction in JNK phosphorylation in fluoride-stimulated BV-2 microglia. The results confirmed that NOX and iNOS played an important role in fluoride inducing oxidative stress and NO production and JNK took part in the oxidative stress induced by fluoride and meanwhile also could be activated by ROS in fluoride-treated BV-2 cells.",
Arsenic,62190,"Baseline and sodium arsenite-induced sister chromatid exchanges in cultured lymphocytes from patients with Blackfoot disease and healthy persons Abstract: A significantly higher frequency of baseline sister chromatid exchange (SCE) was found in the cultured lymphocytes of 13 Blackfoot disease patients (BFP) in comparison with that of healthy persons (HP). Twelve of these BFP consumed well water containing a high concentration of arsenic for 15 years or longer and had switched to drinking tap water 12 years before the time of this study. Sodium arsenite was found to be effective in increasing the SCE frequency and delaying the cell growth of the lymphocytes from both BFP and HP. However, the SCE increment induced by sodium arsenite as well as the progression of the cell divisions in the cultured lymphocytes showed no significant difference between BFP and HP.",
Arsenic,1337533,"Arsenic and arsenic species in cultured oyster (Crassostrea gigas and C. corteziensis) from coastal lagoons of the SE Gulf of California, Mexico Abstract: The aim of this study was to evaluate the bioavailability of arsenic (As) through cultured oyster Crassostrea gigas and Crassostrea corteziensis from four coastal lagoons (SE Gulf of California). Organisms were collected in two seasons (rainy and dry season), and they were analyzed for total arsenic and chemical speciation of this element. The concentrations of As in oyster soft tissue fluctuated between 5.44 and 9.56 ?g/g for rainy season and 6.46 and 8.33 ?g/g for dry season (dry weight) in C. gigas. In C. corteziensis, the As concentrations were &lt;5 ?g/g for both seasons (dry weight). Arsenic speciation indicated arsenobetaine as the major arseno-compound accounting for 43.2-76.3 % of total content of As. Lower contributions were obtained for non-extractable As (11.3-17.5 %) and other molecules such as arsenocholine and methyl-arsonate (&lt;5 %). Inorganic arsenic was detectable in only two samples, at concentrations lower than &lt;0.1 ?g/g. These As data are the first generated for these mollusks in NW Mexico and indicate that C. gigas and C. corteziensis farmed in this area are safe for human consumption in terms of arseno-compounds.",
Arsenic,2149193,"Mechanisms of kidney toxicity for chromium- and arsenic-based preservatives: Potential involvement of a pro-oxidative pathway Abstract: Metals have been extensively used for the preservation of wood. Among metallic conservatives, mixtures of chromated copper arsenate (CCA) were thoroughly used. However, the release and consequent mobilization of such compounds by biota, may culminate in the exertion of toxic chemical effects. The present study intended to show the toxicological effects caused by arsenic (7.2mg/kg body weight), chromium (10.2mg/kg Cr body weight) and the commercial mixture CCA (7.2mg/kg As body weight and 10.2mg/kg Cr body weight) in mice, namely the oxidative stress response (catalase - CAT, glutathione peroxidase - GPx, and glutathione-S-transferases - GSTs), in kidney tissues. The determination of the tested parameters was performed after exposure; organisms were exposed, and then sacrificed at two distinct periods, namely 14 and 96h after the administration of toxicants. Exposure to chromium and arsenic induced significant modifications in the redox state of the test organisms, evidenced by significant alterations in GSTs and GPx activities. No alterations were found concerning the activity of catalase. These findings showed that the chemical mixture used as household product may exert significant toxicological outcomes in exposed animals, such as rodents, conditioning their redox homeostasis and antioxidant response.",
Arsenic,1356355,"The consequences of chronic arsenic poisoning among Moselle wine growers. Pathoanatomical investigations of post-mortem examinations performed between 1960 and 1977 Abstract: Post-mortem findings of 163 wine growers with chronic arsenic poisoning resulting from the use of arsenical insecticides in viniculture. Lung cancers were found in 66% of all wine growers affected; however, nearly the same amount of carcinomas or pre-carcinogenic changes in the skin were observed. The use of arsenic for insecticidal purposes in Germany was banned in 1942; however, this did not mean the eradication of arsenic poisoning. Modern theories of the carcinogenic action of arsenic, the question of tumour latency and the relation of specific cancers to arsenic exposure are discussed.",
Arsenic,849,"Determinants of lung cancer risk among cadmium-exposed workers Abstract: Workers at a cadmium recovery plant in Globe, Colorado, showed an increased risk of lung cancer, which some investigators have attributed to cadmium exposure. We conducted a cohort mortality analysis of this work force and a case-control analysis of the lung cancer cases within this work force in order to assess the probable causes of the lung cancer excess. The Globe plant began as a lead smelter about 1886, switched to arsenic production in 1920, and became a cadmium metal production facility in 1926. Cadmium, arsenic, and cigarette smoking are three potential lung carcinogens found in this workplace. Industrial hygiene data collected from 1943 onward served as the basis for the National Institute for Occupational Safety and Health (NIOSH)-derived exposure algorithm that assigned cadmium exposure estimates to employees based on their work area in the plant and calendar time. Few exposure data existed for substances other than cadmium. Feedstock ore concentrations were used as a surrogate measure of air arsenic levels. The arsenic content of the fines used as feedstock prior to 1940 was considerably higher than that of the fines used after 1940. Smoking histories had been obtained previously for 45% of the workers. A case-control analysis of the 25 cases of lung cancer known to have occurred among these workers through 1982 was conducted using three controls per case, matched by closest data of hire and age at hire. Potential causal agents for lung cancer included cadmium exposure, cigarette smoking, and arsenic exposure. Exposure variables for each case and control included estimated cumulative cadmium exposure in milligram-years per cubic meter, cigarette smoking history, and plant arsenic exposure status at the time of hire. Estimated cumulative cadmium exposures of cases and controls did not differ overall or within the date-of-hire strata. Cases were more than eight times more likely to have been cigarette smokers than were controls. Lung cancer risk in this workplace was more closely related to the period of hire, not to the cumulative cadmium exposure. The period of hire appears to be a surrogate for arsenic exposure as related to feedstock. The measures used here seem to indicate that exposure to arsenic and cigarette particulates, rather than to cadmium particulates, may have caused the increased rate of lung cancer of these workers.",
Arsenic,1357779,"Occupational skin cancers Abstract: Occupational skin cancer was reviewed, and the theory of cutaneous carcinogenesis was summarized. Skin cancer development involves at least three mechanistically distinct steps: initiation of mutagenic damage in cellular DNA, repeated exposure to promoting agents to stimulate proliferation of initiated cells, and conversion of premalignant tumors to malignancy. The conversion step may occur spontaneously, but its frequency may increase with exposure to certain initiating agents. Some agents, such as ultraviolet (UV) radiation, act as both initiators and promotors and are termed complete carcinogens. The roles of UV radiation, ionizing radiation, polycyclic aromatic hydrocarbons, arsenic (7440382), and immunosuppression in nonmelanoma skin cancer was discussed. Arsenic is in a category distinct from other skin carcinogens since skin tumors associated with arsenic have been attributed to ingestion, injection, or inhalation, rather than from skin contact. Immunosuppressive agents have been shown to increase the incidence of tumors on previously sun exposed regions of the body. While data comes from therapeutic rather than occupational exposure to immunosuppressive agents, a similar effect is possible with exposure to immunosuppressive industrial chemicals. Mycosis fungoides and the Sezary syndrome are relatively rare cutaneous neoplasms that arise from thymus derived helper T-lymphocytes. In a study of 44 cases at the U. S. National Cancer Institute, 40 of the patients had a history of often prolonged chemical exposure at the onset of their skin disease. In another study, an industrial background was over four times more common in patients with mycosis fungoides than in the control group, with machinist and machine operator being the most frequent occupational background. Malignant melanoma was discussed. Mortality from malignant melanoma has been steadily increasing in the fair skinned populations over the past several decades. Major etiologic agents in malignant melanoma are UV radiation and environmental chemical agents. Sunlight appears to be an important factor in melanoma genesis, particularly in those with hereditary susceptibility. Other occupational and environmental factors may play a role, but the mechanisms and causal agents are not adequately defined. Increased melanoma incidence has been reported in several occupational groups including chemists, architects, accountants, and business owners, but the interpretation of these associations is confounded by the strong association of melanoma in the general population with higher socioeconomic status.",
Arsenic,1346850,High-resolution magic angle spinning H-1-NMR spectroscopy studies on the renal biochemistry in the bank vole (Clethrionomys glareolus) and the effects of arsenic (As3+) toxicity Abstract: ,
Arsenic,656641,"Visualization and exploratory analysis of epidemiologic data using a novel space time information system Abstract: BACKGROUND: Recent years have seen an expansion in the use of Geographic Information Systems (GIS) in environmental health research. In this field GIS can be used to detect disease clustering, to analyze access to hospital emergency care, to predict environmental outbreaks, and to estimate exposure to toxic compounds. Despite these advances the inability of GIS to properly handle temporal information is increasingly recognised as a significant constraint. The effective representation and visualization of both spatial and temporal dimensions therefore is expected to significantly enhance our ability to undertake environmental health research using time-referenced geospatial data. Especially for diseases with long latency periods (such as cancer) the ability to represent, quantify and model individual exposure through time is a critical component of risk estimation. In response to this need a STIS - a Space Time Information System has been developed to visualize and analyze objects simultaneously through space and time. RESULTS: In this paper we present a ""first use"" of a STIS in a case-control study of the relationship between arsenic exposure and bladder cancer in south eastern Michigan. Individual arsenic exposure is reconstructed by incorporating spatiotemporal data including residential mobility and drinking water habits. The unique contribution of the STIS is its ability to visualize and analyze residential histories over different temporal scales. Participant information is viewed and statistically analyzed using dynamic views in which values of an attribute change through time. These views include tables, graphs (such as histograms and scatterplots), and maps. In addition, these views can be linked and synchronized for complex data exploration using cartographic brushing, statistical brushing, and animation. CONCLUSION: The STIS provides new and powerful ways to visualize and analyze how individual exposure and associated environmental variables change through time. We expect to see innovative space-time methods being utilized in future environmental health research now that the successful ""first use"" of a STIS in exposure reconstruction has been accomplished.",
Arsenic,628023,"Effects of individual and combined exposure to sodium arsenite and sodium fluoride on tissue oxidative stress, arsenic and fluoride levels in male mice Abstract: Arsenic and fluoride are potent toxicants, widely distributed through drinking water and food and often result in adverse health effects. The present study examined the effects of sodium meta-arsenite (100 mg/l in drinking water) and sodium fluoride (5 mg/kg, oral, once daily), administered either alone or in combination for 8 weeks, on various biochemical variables indicative of tissue oxidative stress and cell injury in Swiss albino male mice. A separate group was first exposed to arsenic for 4 weeks followed by 4 weeks of fluoride exposure. Exposure to arsenic or fluoride led to a significant depletion of blood ?-aminolevulinic acid dehydratase (ALAD) activity and glutathione (GSH) level. These changes were accompanied by increased level of blood and tissues reactive oxygen species (ROS) level. An increase in the level of liver and kidney thiobarbituric acid reactive substance (TBARS) along with a concomitant decrease in the activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) and reduced GSH content were observed in both arsenic and fluoride administered mice. The changes were significantly more pronounced in arsenic exposed animals than in fluoride. It was interesting to observe that during combined exposure the toxic effects were less pronounced compared to the effects of arsenic or fluoride alone. In some cases antagonistic effects were noted following co-exposure to arsenic and fluoride. Arsenic and fluoride concentration increased significantly on exposure. Interestingly, their concentration decreased significantly on concomitant exposure for 8 weeks. However, the group which was administered arsenic for 4 weeks followed by 4 weeks of fluoride administration showed no such protection suggesting that the antagonistic effect of fluoride on arsenic or vice versa is possible only during interaction at the gastro intestinal sites. These results are new and interesting and require further exploration.",
Arsenic,202034,"Effect of cadmium, lead and arsenic on the oviposition, hatching and embryonic survival of Biomphalaria glabrata Abstract: Biomphalaria glabrata is a widespread freshwater gastropod mollusc. The easy aquaculture of these organisms allow its use as an accessible tool for contamination bioassays. B. glabrata showed marked metabolic responses when exposed to cadmium, lead and arsenic. Those responses could also affect the reproduction of the snails. Taking into account this hypothesis, B. glabrata were exposed for 96 h (acute laboratory bioassays) to different concentrations of cadmium (0.1, 0.05 and 0 mg/L), lead (0.5, 0.1, 0.05 and 0 mg/L) and arsenic (0.5, 0.1, 0.05 and 0 mg/L). Snails were removed from the aquaria while eggs were left in the same contaminant concentrations. The effect of the assayed toxicants on snail reproduction was registered as the alterations of the total number of laid eggs (TNLE), hatching time and embryonic survival. At 0.10 mg/L cadmium significantly decreased the TNLE (p<0.05) and no embryos survived. The lowest assayed level (0.05 mg/L) of cadmium, delayed the hatching time twice when it was compared with the control group (p<0.01). Lead decreased the TNLE at 0.5 mg/L level (p<0.01). The other assayed doses (0.05 and 0.10 mg/L) also decreased embryonic survival significantly (p<0.05 and p<0.01 respectively) and extended twice the time to hatching (p<0.01). The 0.50 mg/L level killed all embryos. Arsenic at all studied concentrations decreased the TNLE (p<0.05) while the hatching time was increased by 50%. Embryo survival only decreased at the highest level (0.5 mg/L) of arsenic assayed. In summary, the acute exposure (96 h) to cadmium lead and arsenic, altered the reproduction of B. glabrata, modifying the TNLE, hatching time and embryonic survival.",
Arsenic,1017048,"Acquisition of apoptotic resistance in arsenic-induced malignant transformation: role of the JNK signal transduction pathway Abstract: This study examined the role of signal transduction and apoptosis in malignant transformation induced by arsenic. Prior study showed that chronic arsenite exposure (500 nM, &gt; or =18 weeks) induced malignant transformation in rat liver TRL 1215 cells. In the present work, these transformed cells were compared with passage-matched control cells. In addition, TRL 1215 cells were treated subchronically (up to 6 weeks) with arsenic (termed pre-transformed cells) to define events occurring prior to arsenic-induced transformation. Flow cytometry using annexin/FITC revealed that arsenic-induced apoptosis in transformed cells was markedly suppressed in comparison to control or pre-transformed cells. Ro318220, a strong activator of JNK, enhanced arsenite-induced apoptosis in transformed cells. Densitometric analysis of western blots revealed that the ratios of both Bcl-x(L)/Bax and Bcl-2/Bax were significantly increased (&gt;2.5-fold) in arsenic-transformed cells. Transformed, pre-transformed and control cells were treated with arsenic and levels of phosphorylated extracellular signal-regulated kinases, ERK1/2, JNK1/2 and p38 were determined by western blot analysis. The three mitogen-activated protein kinases (MAPKs) were phosphorylated in a dose-dependent fashion in all cell types. However, the levels of phosphorylated JNK1/2 were markedly decreased in the arsenic-transformed cells, whereas in pre-transformed cells the levels of phosphorylated MAPKs remained the same as in control cells. JNK kinase activity was suppressed in transformed cells whereas Ro318220 enhanced this activity. Thus, during arsenic-induced malignant transformation resistance to apoptosis develops, possibly due to perturbation of the JNK pathway.",
Arsenic,1027260,"Bioaccessible arsenic in the home environment in southwest England Abstract: Samples of household dust and garden soil were collected from twenty households in the vicinity of an ex-mining site in southwest England and from nine households in a control village. All samples were analysed by ICP-MS for pseudo-total arsenic (As) concentrations and the results show clearly elevated levels, with maximum As concentrations of 486 microg g(-1) in housedusts and 471 microg g(-1) in garden soils (and mean concentrations of 149 microg g(-1) and 262 microg g(-1), respectively). Arsenic concentrations in all samples from the mining area exceeded the UK Soil Guideline Value (SGV) of 20 microg g(-1). No significant correlation was observed between garden soil and housedust As concentrations. Bioaccessible As concentrations were determined in a small subset of samples using the Physiologically Based Extraction Test (PBET). For the stomach phase of the PBET, bioaccessibility percentages of 10-20% were generally recorded. Higher percentages (generally 30-45%) were recorded in the intestine phases with a maximum value (for one of the housedusts) of 59%. Data from the mining area were used, together with default values for soil ingestion rates and infant body weights from the Contaminated Land Exposure Assessment (CLEA) model, to derive estimates of As intake for infants and small children (0-6 years old). Dose estimates of up to 3.53 microg kg(-1) bw day(-1) for housedusts and 2.43 microg kg(-1) bw day(-1) for garden soils were calculated, compared to the index dose used for the derivation of the SGV of 0.3 microg kg(-1) bw day(-1) (based on health risk assessments). The index dose was exceeded by 75% (18 out of 24) of the estimated As doses that were calculated for children aged 0-6 years, a group which is particularly at risk from exposure via soil and dust ingestion. The results of the present study support the concerns expressed by previous authors about the significant As contamination in southwest England and the potential implications for human health.",
Arsenic,627627,"Toenail arsenic content and cutaneous melanoma in Iowa Abstract: Cutaneous melanoma has the lowest survival rate of all forms of skin cancer. There has been little research investigating the link between arsenic and cutaneous melanoma, although arsenic has been associated with increased risk of nonmelanoma skin cancer. The authors performed a case-control study examining the association between cutaneous melanoma and environmental arsenic exposure among Iowans aged 40 years or older. Participants included 368 cutaneous melanoma cases and 373 colorectal cancer controls diagnosed in 1999 or 2000, frequency matched on gender and age. Participants completed a mailed survey and submitted toenail clippings for analysis of arsenic content by graphite furnace atomic absorption spectrophotometry. The authors found an increased risk of melanoma for participants with elevated toenail arsenic concentrations (odds ratio = 2.1, 95 percent confidence interval: 1.4, 3.3; p-trend = 0.001) and effect modification by prior skin cancer diagnosis (p-interaction = 0.03). The arsenic-melanoma findings in this study are not known to have been previously reported in observational epidemiologic studies involving incident cutaneous melanoma. Therefore, the findings warrant confirmation.",
Arsenic,656926,"Induction of proliferative lesions of the uterus, testes, and liver in swiss mice given repeated injections of sodium arsenate: Possible estrogenic mode of action Abstract: Inorganic arsenic (As) is a human carcinogen but has not been unequivocally proven carcinogenic in rodents. For instance, one older study indicates that repeated iv injections of sodium arsenate might induce lymphomas in Swiss mice (58% incidence) (Osswald and Goerttler, Verh. Dtsch. Ges. Pathol. 55, 289–293, 1971), but it was considered inadequate for critical evaluation of carcinogenic potential largely because of issues in experimental design. Therefore, we studied repeated iv sodium arsenate injection and neoplastic response in male and female Swiss mice. Groups (n = 25) of mice received sodium arsenate (0.5 mg/kg, iv) or saline (control) once/week for 20 weeks and were observed for a total of 96 weeks when the study ended. Differences in survival and body weights were unremarkable. In females, arsenate induced marked increases in the incidence and severity of cystic hyperplasia of the uterus compared against controls. Arsenate also was associated with a rare adenocarcinoma of the uterus. Hyperplastic uterine epithelium from arsenate-exposed animals showed strong positive immunostaining for the proliferating cell nuclear antigen (PCNA). There was also an upregulation of estrogen receptor (ER) immunoreactive protein in the early lesions of uterine luminal and glandular hyperplasia, although a progressive decrease in its expression was seen in the severe hyperplastic or neoplastic epithelium. In common with the preneoplastic and neoplastic gynecological lesions in humans, the levels of immunoreactive inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine-containing proteins were greater in the uterine hyperplastic epidermis and their intensity was positively correlated with the severity of the lesions. Arsenate-induced uterine hyperplastic lesions also showed a strong upregulation of cyclin D1, an estrogen-associated gene product essential for progression through the G1 phase of the cell cycle. In other tissues, arsenate increased testicular interstitial cell hyperplasia incidence and severity over control but without affecting the incidence of tubular degeneration. Arsenate also induced increases in hepatic proliferative lesions (HPL; foci of alteration + neoplasia), but only in females. Significant skin changes (incidence of hyperkeratotic lesions) and renal lesions (severity of nephropathy) also occurred in arsenate-treated females. Thus, repeated arsenate exposure, though not outright tumorigenic in the present study, was associated with proliferative, preneoplastic lesions of the uterus, testes, and liver. Estrogen treatment has been associated with proliferative lesions and tumors of the uterus, female liver, and testes in other studies, supporting a hypothesis that arsenate might somehow act through an estrogenic mode of action.",
Arsenic,1015764,"Genome sequence of the highly efficient arsenite-oxidizing bacterium Achromobacter arsenitoxydans SY8 Abstract: We report the draft genome sequence of Achromobacter arsenitoxydans SY8, the first reported arsenite-oxidizing bacterium belonging to the genus Achromobacter and containing a genomic arsenic island, an intact type III secretion system, and multiple metal(loid) transporters. The genome may be helpful to explore the mechanisms intertwining metal(loid) resistance and pathogenicity.",
Arsenic,67660,"Occupational exposure to chromium, copper and arsenic during work with impregnated wood in joinery shops Abstract: CCA-impregnated timber contains copper, chromium and arsenic (CCA), and occupational exposure to wood dust as well as the CCA compounds may occur in work with such timber. Dust from commercially available impregnated wood has been found to contain hexavalent chromium, which is regarded as a carcinogen. Apart from determinations of the total amounts of the CCA compounds, specific determination of hexavalent chromium is therefore essential. Selective methods have been applied for control of the work environment in six joinery shops. The mean exposure to wood dust was found to be below 1 mg m-3. The mean airborne concentration of arsenic around various types of joinery machines was in the range from 0.54 to 3.1 micrograms m-3. No hexavalent chromium was detected in any samples and no increased concentrations of arsenic were found in urine from the workers. The presence of arsenic in the work-room air must be considered for appropriate assessment of the occupational environment in joinery shops.",
Arsenic,1579281,"Sorption of arsenite, arsenate and thioarsenates to iron oxides and iron sulfides: a kinetic and spectroscopic investigation Abstract: Sorption to iron (Fe) minerals determines the fate of the toxic metalloid arsenic (As) in many subsurface environments. Recently, thiolated As species have been shown to dominate aqueous As speciation under a range of environmentally relevant conditions, thus highlighting the need for a quantitative understanding of their sorption behavior. We conducted batch experiments to measure the time-dependent sorption of two S-substituted arsenate species, mono and tetrathioarsenate, and compared it to the sorption of arsenite and arsenate, in suspensions containing 2-lines ferrihydrite, goethite, mackinawite or pyrite. All four As species strongly sorbed to ferrihydrite. For the other sorbents, binding of the thiolated As species was generally lower compared to arsenate and arsenite, with the exception of the near-instantaneous and complete sorption of monothioarsenate to pyrite. Analysis of the XAS spectra of sorbed complexes implied that monothioarsenate binds to Fe oxides as a monodentate, inner-sphere complex. In the presence of Fe sulfides, monothioarsenate and tetrathioarsenate were both unstable and partially reduced to arsenite. Adsorption of the thiolated As species to the Fe sulfide minerals also caused the substitution of surface sulfur (S) atoms by As and the formation of As-Fe bonds.",
Arsenic,1018101,"Polynucleotide phosphorylase and mitochondrial ATP synthase mediate reduction of arsenate to the more toxic arsenite by forming arsenylated analogues of ADP and ATP Abstract: We have demonstrated that phosphorolytic-arsenolytic enzymes can promote reduction of arsenate (AsV) into the more toxic arsenite (AsIII) because they convert AsV into an arsenylated product in which the arsenic is more reducible by glutathione (GSH) or other thiols to AsIII than in inorganic AsV. We have also shown that mitochondria can rapidly reduce AsV in a process requiring intact oxidative phosphorylation and intramitochondrial GSH. Thus, these organelles might reduce AsV because mitochondrial ATP synthase, using AsV instead of phosphate, arsenylates ADP to ADP-AsV, which in turn is readily reduced by GSH. To test this hypothesis, we first examined whether the RNA-cleaving enzyme polynucleotide phosphorylase (PNPase), which can split poly-adenylate (poly-A) by arsenolysis into units of AMP-AsV (a homologue of ADP-AsV), could also promote reduction of AsV to AsIII in presence of thiols. Indeed, bacterial PNPase markedly facilitated formation of AsIII when incubated with poly-A, AsV, and GSH. PNPase-mediated AsV reduction depended on arsenolysis of poly-A and presence of a thiol. PNPase can also form AMP-AsV from ADP and AsV (termed arsenolysis of ADP). In presence of GSH, this reaction also facilitated AsV reduction in proportion to AMP-AsV production. Although various thiols did not influence the arsenolytic yield of AMP-AsV, they differentially promoted the PNPase-mediated reduction of AsV, with GSH being the most effective. Circumstantial evidence indicated that AMP-AsV formed by PNPase is more reducible to AsIII by GSH than inorganic AsV. Then, we demonstrated that AsV reduction by isolated mitochondria was markedly inhibited by an ADP analogue that enters mitochondria but is not phosphorylated or arsenylated. Furthermore, inhibitors of the export of ATP or ADP-AsV from the mitochondria diminished the increment in AsV reduction caused by adding GSH externally to these organelles whose intramitochondrial GSH had been depleted. Thus, whereas PNPase promotes reduction of AsV by incorporating it into AMP-AsV, the mitochondrial ATP synthase facilitates AsV reduction by forming ADP-AsV; then GSH can easily reduce these arsenylated nucleotides to AsIII.",
Arsenic,710947,"Human toenails as a biomarker of exposure to elevated environmental arsenic Abstract: A pilot study was conducted to determine the applicability of toenails as a biomarker of exposure to elevated environmental arsenic (As) levels. A total of 17 individuals were recruited for the pilot study: 8 residents living near to a former As mine, Devon, UK, forming the exposed group, plus 9 residents from Nottinghamshire, UK, with no anticipated As exposure who were used for comparison as a control group. All toenail samples were thoroughly washed prior to analysis and the wash solutions retained for As determination via ICP-MS to provide an indication of the background environmental As levels for each group. Total As was determined in washed toenail samples via ICP-MS following microwave assisted acid digestion. Concentrations of total As in the toenails of the exposed group were elevated, ranging from 858 to 25,981 ?g/kg (geometric mean = 5406 ?g/kg), compared to the control group whose toenail As concentrations ranged from 73 to 273 ?g/kg (geometric mean = 122 ?g/kg). Higher levels of exogenous As contamination were present on the toenails of the exposed group (geometric mean = 506 ?g/kg) compared to the control group (geometric mean = 4.0 ?g/kg) providing evidence of higher environmental As levels in the exposed group. Total As concentrations in toenail samples were positively correlated to environmental As levels (r = 0.60, p < 0.001). HPLC-ICP-MS analysis of aqueous toenail extracts revealed inorganic arsenite (As(III)) to be the dominant species extracted ( approximately 83%) with lesser amounts of inorganic arsenate (As(V)) and organic dimethylarsinate (DMA(V)) at approximately 13% and approximately 8.5%, respectively. Arsenic speciation in analysed toenail extracts from the two groups was comparable. The only notable difference between groups was the presence of small amounts (<1%) of organic methylarsonate (MA(V)) in two toenail samples from the exposed group. Toenails are presented as a viable biomarker of exposure at sites with elevated environmental As, such as the former mining sites found throughout Devon and Cornwall, UK.",
Arsenic,1019435,"In vitro methylation of arsenite by rabbit liver cytosol: effect of metal ions, metal chelating agents, methyltransferase inhibitors and uremic toxins Abstract: The methylation of carrier-free 74As-arsenite by liver cytosol of Flemish Giant rabbits is highly susceptible to additions of trace elements. In vitro supplementation of essential trace elements like zinc (Zn2+), vanadium (V5+), iron (Fe2+), copper (Cu2+) and selenate was shown to increase the methylation efficiency. Trivalent metal ions (e.g. Al3+, Cr3+ and Fe3+), Hg2+, Tl+ and SeO3(2-) had a deleterious effect. The inhibitory effect of EDTA, oxime and many divalent cations (Ca2+, Mg2+, Sr2+, ...) suggest a co-factor role for a specific divalent metal ion, possibly Zn2+. Chelating agents used in clinical treatment of acute and chronic inorganic arsenic poisoning lower the methylation capacity of cytosol by rendering the trivalent arsenic unavailable for the methyltransferase enzymes. S-adenosylhomocysteine and periodate-oxidized adenosine, inhibitors of s-adenosylmethionine dependent methylation pathways, inhibit the methylation of arsenite. Pyrogallol, a catechol-O-methyltransferase inhibitor, blocks the action of arsenite- and monomethylarsonic methyltransferase enzymes, suggesting a close structural relationship between the active sites of the different enzymes. Some uraemic toxins, namely oxalate, p-cresol, hypoxanthine, homocysteine and myo-inositol, inhibit arsenic methylation.",
Arsenic,628585,"Diabetes mellitus among Swedish art glass workers -- An effect of arsenic exposure? Abstract: OBJECTIVES: The purpose of this study was to search for evidence of an association between occupational arsenic exposure and diabetes mellitus, as implied by the relation of this disease to arsenic in drinking water in a recent study from Taiwan. METHODS: A case-referent analysis on death records of 5498 individuals in the art glass producing part of southeastern Sweden was performed. Out of all the enrolled subjects, 888 were glass workers. According to occupational title, glassblowers, foundry workers, and unspecified workers were regarded as potentially exposed to arsenic. Persons with a diagnosis of diabetes mellitus either as an underlying or contributing cause of death were considered cases. Referents were decedents without any indication of cancer, cardiovascular disease, or diabetes. RESULTS: A slightly elevated risk [Mantel-Haenszel odds ratio (MH-OR) 1.2, 95% confidence interval (95% CI) 0.82-1.8] was found for diabetes mellitus among the glassworks employees, especially in combination with cardiovascular disease (MH-OR 1.4, 95% CI 0.81-2.3). For the glassblowers, other foundry workers and unspecified glassworkers probably exposed to arsenic, the M-H odds ratio was 1.4 (95% CI 0.92-2.2). Unspecified glass workers, who probably included persons with high exposure, carried the higher risk (MH-OR 1.8, 95% CI 1.1-2.8). CONCLUSIONS: The observations from this study provide limited support for the possibility that occupational arsenic exposure could play a role in the development of diabetes mellitus. Many other metallic compounds are also used in art glass production, however, and there is a possibility of confounding.",
Arsenic,627841,"Arsenic stimulates release of cytochrome c from isolated mitochondria via induction of mitochondrial permeability transition Abstract: Arsenic trioxide, As(III), is a known environmental toxicant, co-carcinogen, and potent chemotherapeutic agent. In model experiments with isolated rat liver mitochondria, As(III) stimulated a dose-dependent, cyclosporin A-sensitive release of cytochrome c via induction of mitochondrial permeability transition and subsequent swelling of mitochondria. Mitochondrial GSH does not seem to be a target for As(III) which, however, appears to cause oxidative modification of thiol groups of pore forming proteins, notably adenine nucleotide translocase. In mouse embryonic fibroblasts, 10 microM As(III) stimulated cytochrome c release and apoptosis via a Bax/Bak-dependent mechanism. At high concentrations (125 microM and higher), cells died by Bax/Bak-independent necrosis; at this concentration range As(III) targets mitochondria directly, particularly complex I of the mitochondrial respiratory chain. Since pyruvate, a substrate of complex I, is a predominant mitochondrial substrate in the cell, inhibition of complex I will cause mitochondrial instability and a decrease of Delta psi that facilitates permeability transition and necrotic cell death.",
Arsenic,1015674,"Variants of glutathione s-transferase pi 1 exhibit differential enzymatic activity and inhibition by heavy metals Abstract: Nonsynonymous single nucleotide polymorphisms in glutathione s-transferase pi 1 (GSTP1; Ile/Val 105, Ala/Val 114) have been associated with altered toxicant metabolism in epidemiological cohorts. We explored the impact of GSTP1 genotype on enzyme kinetics and heavy metal inhibition in vitro. Four GSTP1 allozymes (105/114: Ile/Ala, Val/Ala, Ile/Val, Val/Val) were expressed in and purified from Escherichia coli. Enzyme activity assays quantifying the rate of glutathione conjugation with 1-chloro-2,4-dinitrobenzene (CDNB) revealed significant differences in kinetic parameters depending on genotype (p&lt;0.01). Allozymes with Ile105 had better catalytic efficiency and greater affinity for CDNB (mean±SEM: Ile105 Ala114 K(m)=0.33±0.07mM vs. Val105 Ala114 K(m)=1.15±0.07mM). Inhibition of GSTP1 activity by heavy metals was assessed following treatment with mercury (inorganic-HgCl(2), methylmercury-MeHg), selenium, cadmium, lead, arsenic, and manganese. All allozymes were inhibited by HgCl(2) (IC(50) range: 24.1-172?M), MeHg (93.9-480?M), and selenium (43.7-62.8?M). Genotype significantly influenced the potency of mercury with GSTP1 Ile105 Val114 the least sensitive and Val105 Ala114 the most sensitive to inhibition by HgCl(2) and MeHg. Overall, genotype of two nonsynonymous polymorphisms in GSTP1 influenced enzyme kinetics pertaining to an electrophilic substrate and inhibition by two mercury species.",
Arsenic,1349144,Identification of MsHsp23 gene using annealing control primer system Abstract: ,
Arsenic,1355213,"EFFECTS OF DIETARY BORON AND ARSENIC ON THE BEHAVIOR OF MALLARD DUCKLINGS Abstract: BIOSIS COPYRIGHT: BIOL ABS. High concentrations of boron and arsenic have been associated with irrigation drain water and aquatic plants consumed by waterfowl. Both compounds affect the central nervous sytem and cause generalized physiological distress in mammals and waterfowl. We examined sublethal efefcts of boron and arsenic on the behavior of developing mallard ducklings (Anas Platyrhnchos). Day-old ducklings received an untreated diet (control) or a diet containing 100, 400, or 1,600 ppm boron, added as boric acid, or 30, 100, or 300 ppm arsenic, added as sodium aresenate. Activity schedules and behavior durations were analyzed for effects at the various treatment levels. Both boron and arsenic at the highest levels had significant effects on the activity schedules of developing ducklings, including increased time at rest and under the provided heat lamp. We also observed decreases in the amount of time treated ducklings spent in alert behaviors and in the water in comparison to control duckli",
Arsenic,1019206,"Hepatic damage caused by chronic arsenic toxicity in experimental animals Abstract: <strong>OBJECTIVE: </strong>Noncirrhotic fibrosis of the liver is common in subjects chronically consuming ground water geologically contaminated with arsenic, but the mechanism of the hepatic fibrosis is not known. Because lipid peroxidation has been implicated in the development of several other forms of hepatic fibrosis, including iron and copper overload, we have explored the roles of oxidative stress and lipid peroxidation in the causation of hepatic fibrosis in a murine model of chronic arsenic toxicity.<br /><br /><strong>METHODS: </strong>Male BALB/c mice were given drinking water contaminated with arsenic (3.2 mg/L) or arsenic-free (<0.01 mg/L, control) ad libitum. Mice were sacrificed at 3, 6, 9, 12, and 15 months for examination of hepatic histology and assays of hepatic reduced glutathione content, lipid peroxidation, enzymes of the antioxidant defense system, and membrane-bound sodium/potassium ATPase (Na+/K+ ATPase).<br /><br /><strong>RESULTS: </strong>After 12 months of arsenic feeding, the liver weights increased significantly as did serum aspartate aminotransferase and alanine aminotransferase. After 6 months of arsenic feeding, hepatic glutathione and the enzymes glucose-6-phosphate dehydrogenase and glutathione peroxidase were significantly lower than those of the control group. Hepatic catalase activity was significantly reduced at 9 months in the arsenic-fed group, while glutathione-S-transferase and glutathione reductase activities were also significantly reduced at 12 and 15 months. Plasma membrane Na+/K+ ATPase activity was reduced after 6 months while lipid peroxidation increased significantly after 6 months of arsenic feeding. Liver histology remained normal for the first 9 months, but showed fatty infiltration after 12 months of arsenic feeding. Histologic evidence of fibrosis was observed after 15 months.<br /><br /><strong>CONCLUSION: </strong>We have demonstrated hepatic fibrosis due to long-term arsenic toxicity in an animal model. Initial biochemical evidence of hepatic membrane damage, probably due to reduction of glutathione and antioxidant enzymes, may be seen by 6 months. Continued arsenic feeding resulted in fatty liver with serum aminotransferase and alanine aminotransferase elevated at 12 months and hepatic fibrosis at 15 months. The murine model is proposed as relevant to epidemic human toxicity in areas of arsenic contamination.",
Arsenic,1021245,"Respiratory and reproductive characteristics of eastern mosquitofish (Gambusia holbrooki) inhabiting a coal ash settling basin Abstract: Coal fly ash and effluent from coal ash settling basins negatively affects metabolism and reproduction in a variety of organisms, including a number of fish species. Some species, most notably the eastern mosquitofish (Gambusia holbrooki), are known to maintain viable populations in areas contaminated by coal ash. While eastern mosquitofish are present in these systems, their degree of tolerance to coal ash has not been investigated using sublethal metrics of exposure. It is possible that eastern mosquitofish persist in habitats affected by coal ash, but experience significant costs such as changes in metabolism and fecundity. Thus, we investigated the effects of coal ash on standard metabolic rate and reproduction of eastern mosquitofish inhabiting a coal-ash contaminated settling basin. Standard metabolic rates of mosquitofish from the ash contaminated site and a reference site (mean O2 consumption = 0.286 mL/g x h +/- 0.007 and 0.291 +/- 0.008 mL/g x h, respectively) were not significantly different. Despite elevated contaminant concentrations in ash basin females (selenium, arsenic, copper, and cadmium) and their offspring (selenium), brood sizes and offspring viability did not differ between clutches collected from ash basin and reference site females. Our data provide further evidence of the high degree of tolerance of eastern mosquitofish to exposure to aquatic coal ash disposal generated by power plants. However, the basis for such tolerance to ash remains unclear. Further investigations are required to determine whether such tolerance is a result of species-specific characteristics or population characteristics due to local adaptation.",
Arsenic,1033202,"Paul Ehrlich: pioneer of chemotherapy and cure by arsenic (1854-1915) Abstract: Paul Ehrlich's experiments in staining techniques at the end of the nineteenth century resulted in many discoveries which help to form the basis of present research work. Ehrlich's chemotherapy research led to his formulating the arsenic compound, Salvarsan, which was used in the treatment of syphilis during the first half of this century until it was superseded by penicillin.",
Arsenic,1378512,"Sodium arsenite inhibits ERK1/2 phosphorylation in mice lymphocytes stimulated with phytohemagglutinin Abstract: Arsenic immunotoxic effects include inhibition of the proliferative responses elicited by mitogens such as phytohemagglutinin (PHA) in humans and animal lymphocytes, although the molecular mechanism remains to be defined. Previous studies have shown that arsenite induces activation of mitogen-activated protein kinase (MAPK) in non-stimulated lymphocytes, but the effect on PHA-stimulated lymphocytes has not been evaluated. The aim of this study was to establish the possible role of ERK on the inhibition of PHA-induced proliferation of mice T lymphocytes, produced by arsenite. For this purpose, T lymphocytes from female C57BL/6 mice spleen were used. The effects of arsenite on proliferative response of T lymphocytes induced by PHA (10 ug/ml) were measured by incorporation of [3H]-Thymidine and the phosphorylation of ERK1/2 was determined by immunoblotting using an anti-phosphorylated-ERK antibody. The simultaneous treatment of PHA-stimulated lymphocytes with 10 uM arsenite had an inhibitory effect (80%) on PHA-induced proliferation. The phosphorylation of ERK normally elicited by PHA, was inhibited by arsenite at the concentration of 10 uM, but not by 1.0 uM. These results suggest that the MAPK family members, such as ERK, could be involved in the inhibitory effect of sodium arsenite on T-cell proliferation which probably explains in part, immunosupression. Whether this effect is mediated by other MAPK member remains to be determined.",1
Arsenic,1331349,"Regulation of the human CHOP gene promoter by the stress response transcription factor ATF5 via the AARE1 site in human hepatoma HepG2 cells Abstract: <strong>AIMS: </strong>Activating transcription factor (ATF) 5 is a member of the cAMP response element-binding protein (CREB)/ATF family of transcription factors. We have shown that ATF5 is a stress response transcription factor that responds to amino acid limitation, arsenite exposure, or cadmium exposure. In this study we investigated whether ATF5 is involved in the regulation of CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) gene expression.<br /><br /><strong>MAIN METHODS: </strong>We used a transient transfection system to express ATF5 and analyzed the regulation of CHOP gene promoter in human hepatoma, HepG2 cells. We also studied the effect of ATF5 knockdown on arsenite-induced CHOP protein expression and arsenite-induced cell death of HepG2 cells.<br /><br /><strong>KEY FINDINGS: </strong>We showed that ATF5 activates the CHOP gene promoter in HepG2 cells. Both deletion analysis and point mutations of the promoter revealed that amino acid response element (AARE) 1 is responsible for ATF5-dependent promoter activation. Furthermore, the existence of either AARE1 or activating protein-1 (AP-1) site is sufficient for transcriptional activation of the CHOP gene promoter by arsenite exposure, although complete induction requires the existence of both elements. We also demonstrated that knockdown of ATF5 reduced arsenite-induced CHOP protein expression and arsenite-induced cell death of HepG2 cells.<br /><br /><strong>SIGNIFICANCE: </strong>These results suggested that the CHOP gene is a potential target for ATF5, and that ATF5 raises the arsenite-induced CHOP gene expression level via the AARE1 site in HepG2 cells.",
Arsenic,634644,"A simple method based on ICP-MS for estimation of background levels of arsenic, cadmium, copper, manganese, nickel, lead, and selenium in blood of the Brazilian population Abstract: Throughout the world, biomonitoring has become the standard for assessing exposure of individuals to toxic elements as well as for responding to serious environmental public health problems. However, extensive biomonitoring surveys require rapid and simple analytical methods. Thus, a simple and high-throughput method is proposed for the determination of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se) in blood samples by using inductively coupled plasma-mass spectrometry (ICP-MS). Prior to analysis, 200 microl of blood samples was mixed with 500 microl of 10% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 10 min, and subsequently diluted to 10 ml with a solution containing 0.05% w/v ethylenediamine tetraacetic acid (EDTA) + 0.005% v/v Triton X-100. After that, samples were directly analyzed by ICP-MS (ELAN DRC II). Rhodium was selected as an internal standard with matrix-matching calibration. Method detection limits were 0.08, 0.04, 0.5, 0.09, 0.12, 0.04, and 0.1 microg//L for As, Cd, Cu, Mn, Ni, Pb, and Se, respectively. Validation data are provided based on the analysis of blood samples from the trace elements inter-\comparison program operated by the Institut National de Sante Publique du Quebec, Canada. Additional validation was provided by the analysis of human blood samples by the proposed method and by using electrothermal atomic absorption spectrometry (ETAAS). The method was subsequently applied for the estimation of background metal blood values in the Brazilian population. In general, the mean concentrations of As, Cd, Cu, Mn, Ni, Pb, and Se in blood were 1.1, 0.4, 890, 9.6, 2.1, 65.4, and 89.3 microg/L, respectively, and are in agreement with other global populations. Influences of age, gender, smoking habits, alcohol consumption, and geographical variation on the values were also considered. Smoking habits influenced the levels of Cd in blood. The levels of Cu, Mn, and Pb were significantly correlated with gender, whereas Cu and Pb were significantly correlated with age. There were also interesting differences in Mn and Se levels in the population living in the north of Brazil compared to the south.",
Arsenic,1015727,"Metals in the tissues of two fish species from the rare and endemic fish nature reserve in the upper reaches of the Yangtze River, China Abstract: Concentrations of copper, zinc, mercury, and arsenic were measured in the muscle, gill and liver tissues of Coreius heterodon and Pelteobagrus vachelli collected from the rare and endemic fish nature reserve in the upper reaches of the Yangtze River. The concentrations of copper and zinc in the tissues of these two fish species were higher than those of mercury and arsenic. Highest metal concentrations were generally found in fish samples from Yibin. The concentrations of copper, zinc, mercury, and arsenic in C. heterodon were higher than that in P. vachelli. The fish from this study area were not safe for human consumption.",
Arsenic,1022103,"Co-occurrence of arseniasis and fluorosis due to indoor combustion of high fluorine and arsenic content coal in a rural township in northwest China: epidemiological and toxicological aspects Abstract: A large number of fluorosis and arseniasis cases appeared in a mountainous area in northwest China. The residents relied on local inferior coal (&quot;bone coal&quot;) of high fluorine and arsenic content for domestic heating and cooking. For deep-inside information about this rare case of co-endemia of fluorosis and arseniasis in the population in this special exposure scenario, a field investigation in one of the hyperendemic townships was conducted. The resident population registered (n = 27,713) was enrolled in the investigation. All cases were diagnosed and assigned to three symptom severity groups, that is severe, medium, and mild according to Chinese National Standard Criteria GB 16396-96 and to the technical guideline WS/T208-01 or WS/T211-01 issued by the Chinese Ministry of Health. Gender difference was analyzed by standardized incidence ratio. Age trend and severity trend were tested by ?(2) analysis. Fluorosis was diagnosed in 56.7% of the residents. Over 95% of the diagnosed arseniasis cases were simultaneously diagnosed with fluorosis symptoms. Combined fluorosis-arseniasis represented 11.9% of the total fluorosis cases and 6.7% of the local population. No gender-related differences in the prevalence of skeletal, dental, or dermal symptoms inside all severity groups were detected. Symptom severity increased with age. The high frequency of superposition of arseniasis with fluorosis might be due to the fact that the local resident population has been exposed to very high levels of fluorine and arsenic via the same exposure route.",
Arsenic,1354031,"Removal of Arsenic, Boron, and Selenium from Excavated Rocks by Consecutive Washing Abstract: ",
Arsenic,1017495,"Acute exposure of arsenic tri-oxide produces hyperglycemia in both sexes of an Indian teleost, Clarias batrachus (Linn.) Abstract: The present investigation has been conducted to study of the effect of acute exposure of sublethal doses of arsenic tri-oxide (As(2)O(3)) on blood glucose level in an Indian teleost, Clarias batrachus, during their post-breeding season (October to January). The effect was correlated with the sex and doses used with time. Acute exposure of As(2)O(3) of 5, 10 and 15 mg/l for six consecutive days (i.e., 144 h) has been conducted on both sexes of C. batrachus. During the present investigation, it was noticed that the females were more reactive to arsenic in producing hyperglycemia compared to their male counterparts. The difference between males and females to produce hyperglycemia on exposure to arsenic appears to be dose dependent, as lower doses of 5 and 10 mg/l exhibit less difference between the two sexes compared to the highest dose order of 15 mg/l. After 96 h of treatment, a normoglycemic condition was observed in both sexes. However, no significant differences in average normal blood glucose levels were noticed in male and female C. batrachus during the post-breeding season.",
Arsenic,1936037,"Exceptional arsenic (III,V) removal performance of highly porous, nanostructured ZrO2 spheres for fixed bed reactors and the full-scale system modeling Abstract: Highly porous, nanostructured zirconium oxide spheres were fabricated from ZrO2 nanoparticles with the assistance of agar powder to form spheres with size at millimeter level followed with a heat treatment at 450 °C to remove agar network, which provided a simple, low-cost, and safe process for the synthesis of ZrO2 spheres. These ZrO2 spheres had a dual-pore structure, in which interconnected macropores were beneficial for liquid transport and the mesopores could largely increase their surface area (about 98 m(2)/g) for effective contact with arsenic species in water. These ZrO2 spheres demonstrated an even better arsenic removal performance on both As(III) and As(V) than ZrO2 nanoparticles, and could be readily applied to commonly used fixed-bed adsorption reactors in the industry. A short bed adsorbent test was conducted to validate the calculated external mass transport coefficient and the pore diffusion coefficient. The performance of full-scale fixed bed systems with these ZrO2 spheres as the adsorber was estimated by the validated pore surface diffusion modeling. With the empty bed contact time (EBCT) at 10 min and the initial arsenic concentration at 30 ppb, the number of bed volumes that could be treated by these dry ZrO2 spheres reached ?255,000 BVs and ?271,000 BVs for As(III) and As(V), respectively, until the maximum contaminant level of 10 ppb was reached. These ZrO2 spheres are non-toxic, highly stable, and resistant to acid and alkali, have a high arsenic adsorption capacity, and could be easily adapted for various arsenic removal apparatus. Thus, these ZrO2 spheres may have a promising potential for their application in water treatment practice.",
Arsenic,1070438,"Total and inorganic arsenic in rice and rice bran purchased in Thailand Abstract: Concentrations of total and inorganic arsenic were determined in 180 samples of polished and brown rice of three rice types, namely white, jasmine, and sticky, and 44 samples of rice bran from these three rice types purchased in Thailand. Concentrations (expressed in nanograms per gram) of inorganic arsenic in polished white, jasmine, and sticky rice were 68.3 ± 17.6 (with a range of 45.0 to 106), 68.4 ± 15.6 (41.7 to 101), and 75.9 ± 24.8 (43.5 to 156), respectively, while those in the three brown rice samples were 124 ± 34.4 (74.5 to 193), 120 ± 31.6 (73.1 to 174), and 131 ± 35.6 (78.0 to 188), respectively. Inorganic arsenic concentrations (expressed in nanograms per gram) in rice bran produced from the three rice types were 633 ± 182 (375 to 919), 599 ± 112 (447 to 824), and 673 ± 195 (436 to 1,071), respectively. Rice bran contained concentrations of total and inorganic arsenic approximately seven and nine times higher, respectively, than those found in the corresponding polished rice. The levels of inorganic arsenic in the three rice types of both polished and brown rice were within the only published regulatory limit of 200 ng/g.",
Arsenic,2149330,Bacterial community succession during the enrichment of chemolithoautotrophic arsenite oxidizing bacteria at high arsenic concentrations Abstract: ,
Arsenic,1342268,"Diphenylarsinic acid produces behavioral effects in mice relevant to symptoms observed in citizens who ingested polluted well water Abstract: Citizens in an area of Kamisu City, Ibaraki, Japan had exhibited unusual health problems, and pollution of well water by diphenylarsinic acid (DPAA) was found in the area. We examined the effects of DPAA on various behaviors in mice. DPAA was administered to mice through free intake of drinking water for 27 weeks (subchronic exposure) or 57 weeks (chronic exposure), and behavior was examined during exposure. DPAA at 30-100 ppm increased ambulatory activity and the response rate of the shuttle type discrete conditioned avoidance response of mice. DPAA reduced coordination ability on the fixed rod at 100 ppm. DPAA at 7.5-15 ppm also reduced coordination on the rotating rod, although these doses of DPAA did not affect coordination on the fixed rod. Chronic exposure to 7.5-15 ppm of DPAA produced anti-anxiety-like effects in the elevated plus maze test, whereas subchronic exposure to 100 ppm of DPAA produced anxiogenic-like effects. Neither subchronic nor chronic exposure to 7.5-100 ppm of DPAA affected learning ability and/or memory, as evaluated using the passive avoidance response. Exposure to 15-30 ppm of DPAA for 52 weeks did not alter weights of the cerebrum and cerebellum or amounts of neuron marker protein TUJ-1 or astrocyte marker protein glial fibrillary acidic protein in the cerebellum of mice. Behavioral effects observed in mice seem relevant to symptoms observed in patients from Kamisu City.",
Arsenic,1030534,"The expression of urine analysis results—Observations on the use of a specific gravity correction Abstract: Urine analyses are very useful for measuring the extent of exposure to certain toxic substances. The types of specimen obtainable from persons employed in industry, and the effect of concentration variations are discussed. In expressing the results of analysis it is shown that a concentration correction is essential. The correction based on specific gravity is the easiest to apply. The mean specific gravity for persons resident in the U.K. has been found to be around 1·016, a figure considerably lower than the mean of 1·024 used by many workers (particularly in the U.S.A.). The implications of this on the results of urine analysis are indicated.",
Arsenic,1021525,"Arsenic transformation predisposes human skin keratinocytes to UV-induced DNA damage yet enhances their survival apparently by diminishing oxidant response Abstract: Inorganic arsenic and UV, both human skin carcinogens, may act together as skin co-carcinogens. We find human skin keratinocytes (HaCaT cells) are malignantly transformed by low-level arsenite (100nM, 30weeks; termed As-TM cells) and with transformation concurrently undergo full adaptation to arsenic toxicity involving reduced apoptosis and oxidative stress response to high arsenite concentrations. Oxidative DNA damage (ODD) is a possible mechanism in arsenic carcinogenesis and a hallmark of UV-induced skin cancer. In the current work, inorganic arsenite exposure (100nM) did not induce ODD during the 30weeks required for malignant transformation. Although acute UV-treatment (UVA, 25J/cm(2)) increased ODD in passage-matched control cells, once transformed by arsenic to As-TM cells, acute UV actually further increased ODD (&gt;50%). Despite enhanced ODD, As-TM cells were resistant to UV-induced apoptosis. The response of apoptotic factors and oxidative stress genes was strongly mitigated in As-TM cells after UV exposure including increased Bcl2/Bax ratio and reduced Caspase-3, Nrf2, and Keap1 expression. Several Nrf2-related genes (HO-1, GCLs, SOD) showed diminished responses in As-TM cells after UV exposure consistent with reduced oxidant stress response. UV-exposed As-TM cells showed increased expression of cyclin D1 (proliferation gene) and decreased p16 (tumor suppressor). UV exposure enhanced the malignant phenotype of As-TM cells. Thus, the co-carcinogenicity between UV and arsenic in skin cancer might involve adaptation to chronic arsenic exposure generally mitigating the oxidative stress response, allowing apoptotic by-pass after UV and enhanced cell survival even in the face of increased UV-induced oxidative stress and increased ODD.",
Arsenic,1352838,Assessment of Chromium Resistant Bacteria Isolated from Tannery Waste Contaminated Soil in the Region of Fez (Morocco): A Statistical Approach Abstract: ,
Arsenic,2064208,"Enhanced arsenic removal from water by hierarchically porous CeO2-ZrO2 nanospheres: Role of surface- and structure-dependent properties Abstract: Arsenic contaminated natural water is commonly used as drinking water source in some districts of Asia. To meet the increasingly strict drinking water standards, exploration of efficient arsenic removal methods is highly desired. In this study, hierarchically porous CeO2-ZrO2 nanospheres were synthesized, and their suitability as arsenic sorbents was examined. The CeO2-ZrO2 hollow nanospheres showed an adsorption capacity of 27.1 and 9.2mgg(-1) for As(V) and As(III), respectively, at an equilibrium arsenic concentration of 0.01mgL(-1) (the standard for drinking water) under neutral conditions, indicating a high arsenic removal performance of the adsorbent at low arsenic concentrations. Such a great arsenic adsorption capacity was attributed to the high surface hydroxyl density and presence of hierarchically porous network in the hollow nanospheres. The analysis of Fourier transformed infrared spectra and X-ray photoelectron spectroscopy demonstrated that the adsorption of arsenic on the CeO2-ZrO2 nanospheres was completed through the formation of a surface complex by substituting hydroxyl with arsenic species. In addition, the CeO2-ZrO2 nanospheres were able to remove over 97% arsenic in real underground water with initial arsenic concentration of 0.376mgL(-1) to meet the guideline limit of arsenic in drinking water regulated by the World Health Organization without any pre-treatment and/or pH adjustment.",
Arsenic,1019620,"Safer sips: Removing arsenic from drinking water Abstract: U.S. researchers are developing technologies that may someday protect millions of people worldwide whose drinking water is tainted with arsenic. Arsenic is released into water from soil and rock erosion, and is also a by-product of industrial processes including semiconductor manufacturing, petroleum refining, and mining and smelting operations.",
Arsenic,1028878,"Comparative investigations of the genotoxic effects of metals in the single cells gel (SCG) assay and the sister chromatid exchange (SCE) test Abstract: Sodium arsenite (NaAsO2) and cadmium sulphate (CdSO4) were tested for their ability to induce genotoxic effects in the single cell gel (SCG) assay and the sister chromatid exchange (SCE) test in human blood cultures in vitro. Both metals induced DNA damage in white blood cells that was expressed and detected as DNA migration in the SCG assay. Dose dependent effects were seen for cadmium in concentrations from 5 x 10(-4)-5 x 10(-3) M and for arsenic in concentrations from 2 x 10(-4)-1.5 x 10(-3) M. The distribution of DNA migration among cells, a function of dose, revealed that the majority of exposed cells expressed more DNA damage than cells from control cultures and that with increasing length of DNA migration the variability in migration among cells increased as well. Treatment of cells for 2 hr or 24 hr beginning 48 hr after the start of the blood cultures did not increase the SCE frequency in the case of cadmium but caused a small but significant SCE induction with arsenic at the highest concentration. The metal concentrations which could be investigated in the SCE test were much lower due to a strong toxic effect. Metal concentrations which were toxic in the SCE test were without visible effect in the SCG assay. Thus the two endpoints for the determination of genotoxic effects in vitro differed markedly with respect to the detection of genotoxicity induced by metals. These differences and the biological significance of the findings are discussed.",
Arsenic,1019887,"Laboratory case identification of arsenic in Ronpibul village, Thailand (2000-2002) Abstract: Ronpibul village dwellers in the southern part of Thailand have been exposed to arsenic in the water and the environment over three generations. Over the past decades, clean water supplies, utilization and consumption have been introduced to the area. The villagers still use and select rainwater to other forms of potable water. In 2000, the epidemiological survey by Siripitayakunkit (Siripitayakunkit, U. Survey of Chronic Arsenic Poisoning in Ronpiboon, Nakhon Si Thammarat, Thailand, 2000. Proc. 6th International Conference on the Biochemistry of Trace Elements, Guelph, Canada) showed prevalence rate at 24.7%, by using the skin lesion as selection criteria. In 2000-2002, attempt to initiate the local arsenic patient center, we investigated the population at risk in three villages. The laboratory analyses cover urine arsenic level, urine sugar screening and skin lesion classified by dermatologist. The result showed the prevalence of 5.99% of melanosis and 8.67% of hyperkeratosis, 3.84% of urine sugar > 100 mg/dL and 6.33% urine arsenic > 50 microg/g creatinine. There were low to negligible correlation between arsenic urine with urine sugar (r2 = 0.241) and arsenic urine with skin lesion (r2 = 0.058).",
Arsenic,628388,"Arsenic trioxide and melarsoprol induce apoptosis in plasma cell lines and in plasma cells from myeloma patients Abstract: Recent data have renewed the interest for arsenic-containing compounds as anticancer agents. In particular, arsenic trioxide (As2O3) has been demonstrated to be an effective drug in the treatment of acute promyelocytic leukemia by inducing programmed cell death in leukemic cells both in vitro and in vivo. This prompted us to study the in vitro effects of As2O3 and of another arsenical derivative, the organic compound melarsoprol, on human myeloma cells and on the plasma cell differentiation of normal B cells. At pharmacological concentrations (10(-8) to 10(-6) mol/L), As2O3 and melarsoprol caused a dose- and time-dependent inhibition of survival and growth in myeloma cell lines that was, in some, similar to that of acute promyelocytic leukemia cells. Both arsenical compounds induced plasma cell apoptosis, as assessed by 4',6-diamidino-2-phenylindole staining, detection of phosphatidylserine at the cell surface using annexin V, and by the terminal deoxynucleotidyl transferase-mediated nick end labeling assay. As2O3 and melarsoprol also inhibited viability and growth and induced apoptosis in plasma-cell enriched preparations from the bone marrow or blood of myeloma patients. In nonseparated bone marrow samples, both arsenical compounds triggered death in myeloma cells while sparing most myeloid cells, as demonstrated by double staining with annexin V and CD38 or CD15 antibodies. In primary myeloma cells as in cell lines, interleukin 6 did not prevent arsenic-induced cell death or growth inhibition, and no synergistic effect was observed with IFN-alpha. In contrast to As2O3, melarsoprol only slightly reduced the plasma cell differentiation of normal B cells induced by pokeweed mitogen. Both pokeweed mitogen-induced normal plasma cells and malignant plasma cells showed a normal nuclear distribution of PML protein, which was disrupted by As2O3 but not by melarsoprol, suggesting that the two arsenical derivatives acted by different mechanisms. These results point to the use of arsenical derivatives as investigational drugs in the treatment of multiple myeloma.",
Arsenic,628413,"Decreased nitric oxide production in the rat brain after chronic arsenic exposure Abstract: Chronic arsenic exposure is associated with nervous system damage, vascular disease, hepatic and renal damage as well as different types of cancer. Alterations of nitric oxide (NO) in the periphery have been detected after arsenic exposure, and we explored here NO production in the brain. Female Wistar rats were exposed to arsenite in drinking water (4-5 mg/kg/day) from gestation, lactation and until 4 months of age. NOS activity, NO metabolites content, reactive oxygen species production (ROS) and lipid peroxidation (LPx) were determined in vitro in the striatum, and NO production was estimated in vivo measuring citrulline by microdialysis. Exposed animals showed a significantly lower response to NMDA receptor stimulation, reduction of NOS activity and decreased levels of nitrites and nitrates in striatum. These markers of NO function were accompanied by significantly higher levels of LPx and ROS production. These results provide evidence of NO dysfunction in the rat brain associated with arsenic exposure.",
Arsenic,2278339,"Adsorption of Arsenic on MgAl Layered Double Hydroxide Abstract: Groundwater in the Eastern Croatia, as well in the South-eastern Hungary, contains relatively high concentrations of arsenic that can cause chronic toxicity to humans. Therefore, the aim to find an effective composite adsorbent that can be applied for arsenic water remediation by introducing it in the groundwater treatment is very important. The presented results were obtained using layered double hydroxide (LDH) as a sorbing system. MgAl LDH samples with a Mg:Al molar ratio of 2:1 were synthesized. Adsorption of arsenic anions from groundwater samples from Eastern Croatia, as well as adsorption of model aquatic arsenic sample solutions, on MgAl layered double hydroxide was investigated. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for determination of arsenic concentration after adsorption. It was shown that in both cases the adsorption process could be interpreted in terms of Kroeker adsorption isotherm regardless to the presence of other ions in the groundwater. Additionally, the influence of phosphate concentration on adsorption of model arsenic samples was examined and it was shown that (at least in examined range of arsenic and phosphate concentration) there is no significant influence of phosphate on adsorption of arsenic.",
Arsenic,1337609,"Tracking suspended particle transport via radium isotopes ((226)Ra and (228)Ra) through the Apalachicola-Chattahoochee-Flint River system Abstract: Suspended particles in rivers can carry metals, nutrients, and pollutants downstream which can become bioactive in estuaries and coastal marine waters. In river systems with multiple sources of both suspended particles and contamination sources, it is important to assess the hydrologic conditions under which contaminated particles can be delivered to downstream ecosystems. The Apalachicola-Chattahoochee-Flint (ACF) River system in the southeastern United States represents an ideal system to study these hydrologic impacts on particle transport through a heavily-impacted river (the Chattahoochee River) and one much less impacted by anthropogenic activities (the Flint River). We demonstrate here the utility of natural radioisotopes as tracers of suspended particles through the ACF system, where particles contaminated with arsenic (As) and antimony (Sb) have been shown to be contributed from coal-fired power plants along the Chattahoochee River, and have elevated concentrations in the surficial sediments of the Apalachicola Bay Delta. Radium isotopes ((228)Ra and (226)Ra) on suspended particles should vary throughout the different geologic provinces of this river system, allowing differentiation of the relative contributions of the Chattahoochee and Flint Rivers to the suspended load delivered to Lake Seminole, the Apalachicola River, and ultimately to Apalachicola Bay. We also use various geochemical proxies ((40)K, organic carbon, and calcium) to assess the relative composition of suspended particles (lithogenic, organic, and carbonate fractions, respectively) under a range of hydrologic conditions. During low (base) flow conditions, the Flint River contributed 70% of the suspended particle load to both the Apalachicola River and the bay, whereas the Chattahoochee River became the dominant source during higher discharge, contributing 80% of the suspended load to the Apalachicola River and 62% of the particles entering the estuary. Neither of these hydrologic scenarios, which were moderately low flow regimes, appeared to transport particles contaminated with arsenic and antimony to Apalachicola Bay.",
Arsenic,2148539,"A preliminary study of trace metals and porphyrins in excreta of Gentoo penguins (Pygoscelis papua) at two locations of the Antarctic Peninsula Abstract: Even though concentrations of most chemical elements in Antarctic ecosystems are very low as compared to other world's areas, their increasing time trends, as a consequence of the strong population growth and industrial development in countries of the Southern Hemisphere, could be affecting some vulnerable endemic species such as penguins. Concentrations (dry weight) of arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) and porphyrins (copro-, uro- and proto-) were determined in feces of Gentoo penguins (Pygoscelis papua), collected at two locations of the Antarctic Peninsula (O'Higgins and Videla). We found higher (p< 0.05) levels of Hg in excreta of penguin colonies at O'Higgins (7.55 ± 1.28 ?g g-1), whereas penguins at Videla showed the highest concentrations of Cd (1.68 ± 0.71 ?g g-1). Gentoo penguins from O'Higgins site showed higher levels of copro- (1.81 ± 0.61 nmol g-1), uro- (1.74 ± 0.72 nmol g-1) and protoporphyrins (1.24 ± 0.46 nmol g-1), directly related to higher levels of Hg and Pb measured. These findings imply that some Gentoo penguin colonies of the Antarctic Peninsula are likely to develop some biochemical effects through trace metal contamination at some level. These preliminary results raise concerns about anthropogenic pollutants in Antarctica.",
Arsenic,1579269,"Expression of WWOX and FHIT is downregulated by exposure to arsenite in human uroepithelial cells Abstract: Ecological studies in Taiwan, Chile, Argentina, Bangladesh, and Mexico have confirmed significant dose-dependent associations between ingestion of arsenic-contaminated drinking water and the risk of various human malignancies. The FHIT and WWOX genes are active in common fragile sites FRA3B and FRA16D, respectively. Reduced expression of FHIT or WWOX is known to be an early indicator of carcinogen-induced cancers. However, the effect of arsenite on the expressions and molecular mechanisms of these markers is still unclear. The aims of this study were (i) to observe the expression of ATR, WWOX and FHIT proteins in urothelial carcinoma (UC) between endemic and non-endemic areas of blackfoot disease (BFD) by immunohistochemical analyses; (ii) to compare expression of these genes between arsenite-treated SV-HUC-1 human epithelial cells and rat uroepithelial cells; and (iii) to determine the role of DNMT and MEK inhibitors on expressions of WWOX and FHIT in response to arsenite in SV-HUC-1. The experiments revealed that expressions of ATR, WWOX and FHIT in UC significantly differed between BFD areas and non-BFD areas (p=0.003, 0.009 and 0.021, respectively). In fact, the results for the arsenite-treated groups showed that ATR, WWOX and FHIT are downregulated by arsenite in SV-HUC-1. However, the inhibitors suppressed the effects of arsenite on WWOX and FHIT proteins and mRNA expression. In conclusion, arsenite decreased expressions of ATR, WWOX and FHIT via ERK1/2 activation in SV-HUC-1 cells. These findings confirm that dysregulations of these markers may contribute to arsenite-induced carcinogenesis.",
Arsenic,1016437,"Protective effects of selenium, calcium, and magnesium against arsenic-induced oxidative stress in male rats Abstract: Inorganic arsenic is a potent carcinogen and environmental pollutant. More than one hundred million people are reported to be exposed to elevated concentrations of arsenic mainly via drinking water. Essential trace elements can affect toxicity of metals by interacting with metals at the primary site of action and can also modify the body's response to toxic metals by altering their metabolism and transport. This study investigates the effects of concomitant administration of selenium, magnesium, and calcium with arsenic on blood biochemistry and oxidative stress. Selenium was the most effective in reducing arsenic-induced inhibition of blood delta-aminolevulinic acid dehydratase (ALAD) activity and liver oxidative stress. Calcium and magnesium also showed favourable effects on haematological and other biochemical parameters. Because selenium was the most effective, it should be added to chelation therapy to achieve the best protective effects against arsenic poisoning in humans.",
Arsenic,1381713,"Angiosarcoma of the liver: annual occurrence and aetiology in Great Britain Abstract: The annual occurrence of angiosarcoma of the liver (ASL) in Britain from 1963 to 1977 was studied, including clinical and occupational details for those cases agreed as ASL by a panel of histopathologists. Thirty-five cases (28 men, six women, and one infant girl) were agreed as ASL. The increase in the incidence of ASL observed in recent years was attributable to Thorotrast (thorium dioxide) usage (eight cases) and exposure to vinyl chloride (two cases) in the past. In its clinical presentation and prognosis ASL resembled primary liver carcinoma, except that extrahepatic metastases were found in only eight (23%) cases, and haemoperitoneum ws more common in those cases due to Thorotrast. The results suggested a possible increased risk of ASL in the electrical and plastics fabrication industries, but information on exposure was inadequate to implicate specific chemicals. The clinical features of one case were indicative of arsenical intoxication, but medications in the other patients did not appear to be of aetiological importance.",
Arsenic,627261,"Oxidative stress mediates sodium arsenite-induced expression of heme oxygenase-1, monocyte chemoattractant protein-1, and interleukin-6 in vascular smooth muscle cells Abstract: Arsenic exposure is associated with an increased risk of vascular disorders, and results in increased oxidative stress in endothelial cells and vascular smooth muscle cells (VSMCs). Since oxidative stress is involved in regulating the expression of genes related to atherogenesis, we investigated its involvement in the enhanced expression of three atherosclerosis-related genes coding for heme oxygenase-1 (HO-1), monocyte chemoattractant protein-1 (MCP-1), and interleukin-6 (IL-6) in VSMCs treated with inorganic sodium arsenite (iAs). In human VSMCs (hVSMCs) and rat VSMCs (rVSMCs), HO-1, MCP-1, and IL-6 mRNA levels were significantly increased by iAs treatment. An increase in HO-1 protein levels in hVSMCs was confirmed by Western blotting technique, while increased MCP-1 and IL-6 secretion by hVSMCs was demonstrated by enzyme-linked immunosorbent assay. Although modulators of oxidative stress inhibited this iAs-induced increase in the expression of these three genes, different modulators had differential effects. In iAs-treated rVSMCs, catalase, dimethylsulfoxide, and L-omega-nitro-L-arginine significantly inhibited the increase in expression of all three genes, allopurinol inhibited the increase in MCP-1 and IL-6 expression, but had no effect on HO-1 expression, while superoxide dismutase had no significant effect on HO-1 expression, but had an inhibitory effect on IL-6 expression and a stimulatory effect on MCP-1 expression. Therefore, iAs may enhance the expression of HO-1, MCP-1, and IL-6 in VSMCs via different reactive oxygen molecules. Furthermore, using tin protoporphyrin IX (SnPP) and anti-MCP-1 antibody to abolish iAs-induced HO-1 and MCP-1 activity, respectively, shows that HO-1 has protective effect against iAs-induced injury in VSMCs and MCP-1 is chemoattractive to human monocytes, THP-1.",
Arsenic,1579338,"Label-free colorimetric detection of arsenite utilizing g-/t-rich oligonucleotides and unmodified au nanoparticles Abstract: &quot;Free&quot; arsenite sensor: Based on the principle that G-/T-rich single-stranded DNA (ssDNA) and folded DNA bound to arsenite have different propensities to adsorb onto Au nanoparticles (Au NPs) in colloidal solution, a label-free colorimetric assay for arsenite sensing based on color changes associated with the aggregation of Au NPs has been designed.",
Arsenic,1351806,"Comparison of impedance-based sensors for cell adhesion monitoring and in vitro methods for detecting cytotoxicity induced by chemicals Abstract: The recent European Commission REACH (Registration, Evaluation and Authorisation of Chemicals) policy outlines a plan for toxicological testing by using alternative non-animal in vitro methods. In this context, there is a need to develop and standardise high-throughput screening (HTS) methods for studying the cytotoxicity induced by chemicals. Electrochemical impedance spectroscopy (EIS) can be considered as a complementary technique to alternative in vitro testing for studying cell adhesion to the substrate, and can give real-time and kinetic information on cell responses to a toxicant. This paper describes the development of a home-made chip based on impedance spectroscopy, and its application in studying the kinetics of BALB/3T3 cell adhesion and the cellular responses to a toxic product as a function of time. Concentrations of sodium arsenite, ranging from 10 microM up to 1000 microM, were tested in the system, and the results were compared with those obtained with standard protocols used to study basal cytotoxicity induced by chemicals in the BALB/3T3 cell line. The results show that the sensitivity of the developed chip was better than that with the MTT test, with the additional advantages of online monitoring.",
Arsenic,2337169,"Transcriptome profiling of genes and pathways associated with arsenic toxicity and tolerance in Arabidopsis Abstract: BACKGROUND: Arsenic (As) is a toxic metalloid found ubiquitously in the environment and widely considered an acute poison and carcinogen. However, the molecular mechanisms of the plant response to As and ensuing tolerance have not been extensively characterized. Here, we report on transcriptional changes with As treatment in two Arabidopsis accessions, Col-0 and Ws-2. RESULTS: The root elongation rate was greater for Col-0 than Ws-2 with As exposure. Accumulation of As was lower in the more tolerant accession Col-0 than in Ws-2. We compared the effect of As exposure on genome-wide gene expression in the two accessions by comparative microarray assay. The genes related to heat response and oxidative stresses were common to both accessions, which indicates conserved As stress-associated responses for the two accessions. Most of the specific response genes encoded heat shock proteins, heat shock factors, ubiquitin and aquaporin transporters. Genes coding for ethylene-signalling components were enriched in As-tolerant Col-0 with As exposure. A tolerance-associated gene candidate encoding Leucine-Rich Repeat receptor-like kinase VIII (LRR-RLK VIII) was selected for functional characterization. Genetic loss-of-function analysis of the LRR-RLK VIII gene revealed altered As sensitivity and the metal accumulation in roots. CONCLUSIONS: Thus, ethylene-related pathways, maintenance of protein structure and LRR-RLK VIII-mediated signalling may be important mechanisms for toxicity and tolerance to As in the species. Here, we provide a comprehensive survey of global transcriptional regulation for As and identify stress- and tolerance-associated genes responding to As.",
Arsenic,2064204,"Influences of wood preservation, lumber size, and weather on field leaching of red pine lumber Abstract: Alkaline copper quaternary (ACQ) is a widely used wood preservative. This study evaluated leachate volume generation and contaminant leaching from ACQ-treated lumber during rainfall events in comparison to untreated lumber. The influences of wood preservation with ACQ, lumber size, and weather on leachate generation ratio and contaminant concentrations in wood leachate were investigated with four red pine lumber piles exposed to natural weather conditions. The average volumetric ratio of leachate to rainfall was significantly higher for the large-lumber piles (0.62) compared with the small-lumber piles (0.35). Less leachate was generated in the ACQ-treated lumber piles (0.42) than the untreated lumber piles (0.55). Leachate volume could be predicted with rainfall depth, air temperature, and wetted lumber surface area. Lumber size did not make a statistically significant difference in leachate quality except for zinc concentration. The average copper concentrations were 4034?g/L in the leachate from the ACQ-treated lumber piles and 87?g/L in the leachate from the untreated lumber piles. Moreover, ACQ treatment significantly increased leaching of arsenic and total dissolved solids. Copper concentration in leachate from ACQ-treated lumber can be predicted with rainfall intensity, the time interval between two consecutive leachate-generating events, rain copper concentration, and rain pH.",
Arsenic,1020005,"Induction of DNA double strand breaks by arsenite: comparative studies with DNA breaks induced by X-rays Abstract: Chinese hamster ovary (CHO-K1) cell line and two of its DNA double strand break (DSB) repair deficient mutant cell lines, xrs-5 (Ku80 mutant) and irs-20 (DNA-PKcs mutant), were treated with various concentrations of sodium arsenite for 2.5h, and the colony forming abilities were studied. The wild type cells showed the highest cell survival, while xrs-5 cells showed the lowest survival, and irs-20 cells had an intermediate survival. These results are very similar to the cell survival curves induced by X-rays in these three cell lines. Our data also show the dose dependent induction of DNA-DSBs in these cell lines exposed to arsenite. However, in order to obtain a similar cell survival in wild type cells, twice as many DNA-DSBs are necessary with arsenite exposure when compared with X-rays, suggesting that the types of DNA lesions leading to DSB induced by arsenite are different from those by X-rays. Based on these data, further mechanistic investigations including the involvement of DNA-DSB repair proteins are warranted in the recovery process from arsenic (As) exposure.",
Arsenic,2278051,"Arabidopsis WRKY45 Transcription Factor Activates PHT1;1 Expression in Response to Phosphate Starvation Abstract: The WRKY transcription factor family has more than 70 members in the Arabidopsis genome, and some of them are involved in plant responses to biotic and abiotic stresses. This study evaluated the role of WRKY45 in regulating phosphate (Pi) uptake in Arabidopsis. WRKY45 was localized in the nucleus and mainly expressed in roots. During Pi starvation, WRKY45 expression was markedly induced, typically in roots. WRKY45 overexpression in Arabidopsis increased Pi content and uptake, while RNAi suppression of WRKY45 decreased Pi content and uptake. Furthermore, the WRKY45-overexpressing lines were more sensitive to arsenate, the analogue of phosphate, compared with wild-type seedlings. These results indicate that WRKY45 positively regulates Arabidopsis Pi uptake. qRT-PCR and ?-glucuronidase staining assays showed that PHT1;1 expression was enhanced in the WRKY45-overexpressing lines and slightly repressed in the WRKY45 RNAi line. ChIP and EMSA results indicated that WRKY45 can bind to two W-boxes within the PHT1;1 promoter, confirming the role of WRKY45 in directly up-regulating PHT1;1 expression. The pht1;1 mutant showed decreased Pi content and uptake, and overexpression of PHT1;1 resulted in enhanced Pi content and uptake. Furthermore, the PHT1;1-overexpressing line was much more sensitive to arsenate than WRKY45-overexpressing and wild-type seedlings, indicating that PHT1;1 overexpression can enhance Arabidopsis Pi uptake. Moreover, the enhanced Pi uptake and the increased arsenate-sensitivity of the WRKY45-overexpressing line was impaired by pht1;1 (35S:WRKY45-18::pht1;1), demonstrating an epistatic genetic regulation between WRKY45 and PHT1;1. Together, our results demonstrate that WRKY45 is involved in Arabidopsis response to Pi starvation by direct up-regulation of PHT1;1 expression.",
Arsenic,2278878,"A case of primary peritoneal carcinoma: evidence for a precursor in the fallopian tube Abstract: <strong>BACKGROUND: </strong>Primary high-grade serous peritoneal carcinoma (PPSC) is a rare malignancy with an ambiguous pathogenesis.<br /><br /><strong>CASE REPORT: </strong>We report on a 51-year-old woman presenting with a routine smear test cytology suspicious of adenocarcinoma. She underwent hysteroscopy, laparsocopy with multiple biopsies and bilateral salpingoophorectomy. She was diagnosed with a serous tubal intraepithelial carcinoma in situ (STIC) in the right fallopian tube. Subsequently, she underwent radical surgery and was diagnosed with peritoneal high-grade serous carcinoma. Interestingly, both ovaries remained histologically tumour-free.<br /><br /><strong>DISCUSSION: </strong>High-grade serous carcinomas that arise on the peritoneum with tumour-free ovaries are rare. The findings in this case, coupled with current evidence, strongly suggest a precursor lesion in the fallopian tube (STIC lesions). The clinical implications of this theory reside in the potential for improving early detection strategies. Nonetheless, more data on precursor lesions in the fallopian tubes and their transformation to serous carcinoma are required to plan for future screening methods.",
Arsenic,2298735,"Silicon nutrition alleviates the negative impacts of arsenic on the photosynthetic apparatus of rice leaves: An analysis of the key limitations of photosynthesis Abstract: Silicon (Si) plays important roles in alleviating various abiotic stresses. In rice (Oryza sativa), arsenic (As) is believed to share the Si transport pathway for entry into roots, and Si has been demonstrated to decrease As concentrations. However, the physiological mechanisms through which Si might alleviate As toxicity in plants remain poorly elucidated. We combined detailed gas exchange measurements with chlorophyll fluorescence analysis to examine the effects of Si nutrition on photosynthetic performance in rice plants (a wild-type cultivar and its lsi1 mutant defective in Si uptake) challenged with As (arsenite). As treatment impaired carbon fixation (particularly in the wild-type genotype) that was unrelated to photochemical or biochemical limitations but, rather, was largely associated with decreased leaf conductance at the stomata and mesophyll levels. Indeed, regardless of the genotypes, in the plants challenged with As, photosynthetic rates correlated strongly with both stomatal (r(2) = 0.90) and mesophyll (r(2) = 0.95) conductances, and these conductances were, in turn, linearly correlated with each other. The As-related impairments to carbon fixation could be considerably reverted by Si in a time- and genotype-dependent manner. In conclusion, we identified Si nutrition as an important target in an attempt to not only decrease As concentrations but also to ameliorate the photosynthetic performance of rice plants challenged with As.",
Arsenic,1326957,"The Environmental Toxin Arsenite Induces Tau Hyperphosphorylation † Abstract: Abnormally hyperphosphorylated tau polymers known as paired helical filaments constitute one of the major characteristic lesions that lead to the demise of neurons in Alzheimer's disease. Here, we demonstrate that the environmental toxin arsenite causes a significant increase in the phosphorylation of several amino acid residues (Thr-181, Ser-202, Thr-205, Thr-231, Ser-262, Ser-356, Ser-396, and Ser-404) in tau, which are also hyperphosphorylated under pathological conditions. Complementary phosphopeptide mapping revealed a dramatic increase in the (32)P-labeling of many peptides in tau following arsenite treatment. Although arsenite activates extracellular-signal regulated kinases-1/-2 and stress-activated protein kinases, these enzymes did not contribute to the arsenite-increased phosphorylation, nor did they appear to normally modify tau in vivo. Tau phosphorylation induced by arsenite did not involve glycogen synthase kinase-3 or protein phosphatase-1 or -2, but the activity responsible for tau hyperphosphorylation could be inhibited with the protein kinase inhibitor roscovitine. The effects of arsenite on the phosphorylation of some tau mutations (DeltaKappa280, V337M, and R406W) associated with frontal-temporal dementia with parkinsonism linked to chromosome 17 was analyzed. The unchallenged and arsenite-induced phosphorylation of some mutant proteins, especially R406W, was altered at several phosphorylation sites, indicating that these mutations can significantly affect the structure of tau in vivo. Although the major kinase(s) involved in aberrant tau phosphorylation remains elusive, these results indicate that environmental factors, such as arsenite, may be involved in the cascade leading to deregulation of tau function associated with neurodegeneration.",
Arsenic,1337329,"Assessment of cytomegalovirus specific cell-mediated immunity for the prediction of cytomegalovirus disease in high-risk solid-organ transplant recipients: a multicenter cohort study Abstract: Background.?Cytomegalovirus (CMV) disease remains an important problem in solid-organ transplant (SOT) recipients, with the greatest risk among donor CMV seropositive, recipient seronegative [D+/R-] patients. CMV-specific cell-mediated immunity may be able to predict which patients will develop CMV disease.Methods.?We prospectively included D+/R- patients who received antiviral prophylaxis. We used the Quantiferon-CMV assay (Cellestis Ltd, Melbourne, Australia) to measure interferon-? levels following in vitro stimulation with CMV antigens. The test was performed at the end of prophylaxis, and one and two months later. The primary outcome was the incidence of CMV disease at 12 months post-transplant. We calculated positive and negative predictive values of the assay for protection from CMV disease.Results.?Overall, 28/127 (22%) patients developed CMV disease. Of 124 evaluable patients, 31 (25%) had a positive result, 81 (65.3%) had a negative result, and 12 (9.7%) had an indeterminate result (negative mitogen and CMV antigen) of the Quantiferon-CMV assay. At 12 months, patients with a positive result had a subsequent lower incidence of CMV disease, than patients with a negative and an indeterminate result (6.4% vs. 22.2% vs. 58.3%, respectively, p&lt;0.001). Positive and negative predictive values of the assay for protection from CMV disease were 0.90 (95% CI 0.74-0.98) and 0.27 (95% CI 0.18-0.37), respectively.Conclusions.?This assay may be useful to predict if patients are at low, intermediate, or high risk for the development of subsequent CMV disease after prophylaxis.",
Arsenic,2149307,"STUDY ON PROPERTIES OF ALLOYS WITH GALLIUM, ANTIMONY AND ZINC FROM RECYCLING Abstract: ",
Arsenic,1579244,"Predicting water consumption habits for seven arsenic-safe water options in Bangladesh Abstract: BACKGROUND: In Bangladesh, 20 million people are at the risk of developing arsenicosis because of excessive arsenic intake. Despite increased awareness, many of the implemented arsenic-safe water options are not being sufficiently used by the population. This study investigated the role of social-cognitive factors in explaining the habitual use of arsenic-safe water options. METHODS: Eight hundred seventy-two randomly selected households in six arsenic-affected districts of rural Bangladesh, which had access to an arsenic-safe water option, were interviewed using structured face-to-face interviews in November 2009. Habitual use of arsenic-safe water options, severity, vulnerability, affective and instrumental attitudes, injunctive and descriptive norms, self-efficacy, and coping planning were measured. The data were analyzed using multiple linear regressions. RESULTS: Linear regression revealed that self-efficacy (B = 0.42, SE = .03, p &lt; .001), the instrumental attitude towards the safe water option (B = 0.24, SE = .04, p &lt; .001), the affective attitude towards contaminated tube wells (B = -0.04, SE = .02, p = .024), vulnerability (B = -0.20, SE = .02, p &lt; .001), as well as injunctive (B = 0.08, SE = 0.04, p = .049) and descriptive norms (B = 0.34, SE = .03, p &lt; .001) primarily explained the habitual use of arsenic-safe water options (R2 = 0.688). This model proved highly generalizable to all seven arsenic-safe water options investigated, even though habitual use of single options were predicted on the basis of parameters estimated without these options. CONCLUSIONS: This general model for the habitual use of arsenic-safe water options may prove useful to predict other water consumption habits. Behavior-change interventions are derived from the model to promote the habitual use of arsenic-safe water options.",
Arsenic,1508691,"Both G3BP1 and G3BP2 contribute to stress granule formation Abstract: Upon exposure to various environmental stresses such as arsenite, hypoxia, and heat shock, cells inhibit their translation and apoptosis and then repair stress-induced alterations, such as DNA damage and the accumulation of misfolded proteins. These types of stresses induce the formation of cytoplasmic RNA granules called stress granules (SGs). SGs are storage sites for the many mRNAs released from disassembled polysomes under these stress conditions and are essential for the selective translation of stress-inducible genes. Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) is a component of SGs that initiates the assembly of SGs by forming a multimer. In this study, we examined the role of G3BP2, a close relative of G3BP1, in SG formation. Although single knockdown of either G3BP1 or G3BP2 in 293T cells partially reduced the number of SG-positive cells induced by arsenite, the knockdowns of both genes significantly reduced the number. G3BP2 formed a homo-multimer and a hetero-multimer with G3BP1. Moreover, like G3BP1, the overexpression of G3BP2 induced SGs even without stress stimuli. Collectively, these results suggest that both G3BP1 and G3BP2 play a role in the formation of SGs in various human cells and thereby recovery from these cellular stresses.",
Arsenic,2088350,"Arsenate retention by epipsammic biofilms developed on streambed sediments: Influence of phosphate Abstract: Natural geological conditions together with the impact of human activities could produce environmental problems due to high As concentrations. The aim of this study was to assess the role of epipsammic biofilm-sediment systems onto As (V) sorption and to evaluate the effect of the presence of equimolar P concentrations on As retention. A natural biofilm was grown on sediment samples in the laboratory, using river water as nutrient supplier. Sorption experiments with initial As concentrations 0, 5, 25, 50, 100, 250, and 500??g?L?1 were performed. The average percentage of As sorbed was and % for the sediment and biofilm-sediment systems, respectively. Phosphate decreased by 25% the As sorption capactity in the sediment devoid of biofilm, whereas no significant effect was observed in the systems with biofilm. Freundlich, Sips, and Toth models were the best to describe experimental data. The maximum As sorption capacity of the sediment and biofilm-sediment systems was, respectively, 6.6 and 6.8??g?g?1 and 4.5 and 7.8??g?g?1 in the presence of P. In conclusion, epipsammic biofilms play an important role in the environmental quality of river systems, increasing As retention by the system, especially in environments where both As and P occur simultaneously.",
Arsenic,735975,"Biomonitoring for chromium and arsenic in timber treatment plant workers exposed to CCA wood preservatives Abstract: This study reports a survey of occupational exposure to copper chrome arsenic (CCA) based wood preservatives during vacuum pressure timber impregnation. The survey involved biological monitoring based on analysis of chromium and arsenic in urine samples collected from UK workers. The aim of the study was to determine the extent of occupational exposure to arsenic and chromium in the UK timber treatment industry. The objectives were to collect and analyse urine samples from as many workers as possible, where CCA wood preservatives might be used, at 6 monthly intervals for 2 years. In addition, to investigate day-to-day variations in urinary excretion of chrome and arsenic by collecting and analysing three samples a week for 3 weeks in subsets of workers and controls (people not occupationally exposed). All urine samples were analysed for chromium and inorganic arsenic. To investigate any residual interference every sample was accompanied by a short questionnaire about recent consumption of seafood and smoking. The analytical methods for arsenic used a hydride generation technique to reduce interference from dietary sources of arsenic and also a technique that would measure total arsenic concentration in urine. The main findings show that workers exposed to CCA wood preservatives have concentrations of inorganic arsenic and chromium in urine that are significantly higher than those from non-occupationally exposed people but below biological monitoring guidance values that would indicate inhalation exposure at UK occupational exposure limits for chromium and arsenic. The effects of consumption of seafood on urinary arsenic were not significant using the hydride generation method for inorganic arsenic but were significant if 'total' arsenic was measured. The 'total' arsenic method could not distinguish CCA workers from controls and is clearly unsuitable for assessment of occupational exposure to arsenic. There was a significant increase in the urinary concentration of chromium in workers over the four sample collection rounds indicating increasing exposure to chromium during the 2 years of the study. This unexpected finding may be worth further investigation. Overall, the study demonstrated the utility of biological monitoring for assessment of occupational exposure to chromium and arsenic.",
Arsenic,1357247,"Arsenite, but Not Cadmium, Induces Ornithine Decarboxylase and Heme Oxygenase in Rat Liver: Relevance to Arsenic Carcinogenesis Abstract: The effects of arsenic (7440382) and cadmium (7440439) on hepatic markers of carcinogenicity were studied in rats. Female Sprague-Dawley-rats were gavaged with 1.6, 8.2, or 24.6mg/kg sodium-arsenite (7784465) or 3.52, 17.6, or 52.8mg/kg cadmium-chloride (10108642). Selected rats were killed 4 or 21 hours later. Livers were assayed for ornithine-decarboxylase (ODC), glutathione, cytochrome-P-450 (P450), heme-oxygenase, and DNA damage. Blood samples were analyzed for serum alanine-aminotransferase (ALT). Lungs from sodium-arsenite treated rats were assayed for DNA damage, ODC, glutathione, P450, and heme-oxygenase. Sodium-arsenite did not induce DNA damage or alter lung ODC, glutathione, P450, or heme-oxygenase. In the liver, sodium-arsenite at 1.6 and 24.6mg/kg significantly increased ODC activity and at 8.2 and 24.6mg/kg significantly increased heme-oxygenase activity. Sodium-arsenite did not affect induce DNA damage or alter glutathione or P450 content in the liver or affect serum ALT activity. Cadmium-chloride did not affect any of the examined parameters. The authors conclude that sodium-arsenite, but not cadmium-chloride, induces hepatic ODC and heme-oxygenase in rats. The fact that no DNA damage was observed suggests that sodium-arsenite is more likely to be a nongenotoxic carcinogen than a genotoxic carcinogen.",
Arsenic,628800,"Male reproductive toxicity of sodium arsenite in mice Abstract: The effect of chronic oral exposure to arsenic on male mouse testicular and accessory sex organ weights, sperm parameters and testicular marker enzymes was studied. In addition, the distribution of arsenic in reproductive organs was measured using atomic absorption spectrophotometry. Sodium arsenite administered to mice (Mus musculus) via drinking water at a dose of 53.39 micromol/L (4 ppm As) for 365 days caused a decrease in the absolute and relative testicular weight. However, epididymal and accessory sex organ weight was similar to control. The activities of marker testicular enzymes such as sorbitol dehydrogenase, acid phosphatase and 17beta-hydroxy-steroid dehydrogenase (17beta-HSD) were significantly decreased, but those of lactate dehydrogenase and gamma-glutamyl transpeptidase (gamma-GT) were significantly increased. A decrease in sperm count and sperm motility, along with an increase in abnormal sperm, was observed in arsenite-exposed mice. A significant accumulation of arsenic in testes, epididymis, seminal vesicle and prostate gland was observed in treated animals. Thus long term exposure (365 days) at the dose level of 53.39 micromol/L sodium arsenite (4 ppm As), to which human beings are likely to be exposed via drinking water, may cause testicular and spermatotoxic effect.",
Arsenic,2345678,"Detecting Well Casing Leaks in Bangladesh Using a Salt Spiking Method Abstract: We apply fluid-replacement logging in arsenic-contaminated regions of Bangladesh using a low-cost, down-well fluid conductivity logging tool to detect leaks in the cased section of wells. The fluid-conductivity tool is designed for the developing world: it is lightweight and easily transportable, operable by one person, and can be built for minimal cost. The fluid-replacement test identifies leaking casing by comparison of fluid conductivity logs collected before and after spiking the wellbore with a sodium chloride tracer. Here, we present results of fluid-replacement logging tests from both leaking and non-leaking casing from wells in Araihazar and Munshiganj, Bangladesh, and demonstrate that the low-cost tool produces measurements comparable to those obtained with a standard geophysical logging tool. Finally, we suggest well testing procedures and approaches for preventing casing leaks in Bangladesh and other developing countries.",
Arsenic,628785,"Additional danger of arsenic exposure through inhalation from burning of cow dung cakes laced with arsenic as a fuel in arsenic affected villages in Ganga-Meghna-Brahmaputra plain Abstract: In arsenic contaminated areas of the Ganga-Meghna-Brahmaputra (GMB) plain (area 569,749 sq. km; population over 500 million) where traditionally cow dung cake is used as a fuel in unventilated ovens for cooking purposes, people are simply exposed to 1859.2 ng arsenic per day through direct inhalation, of which 464.8 ng could be absorbed in respiratory tract.",
Arsenic,1339180,"Quantitative relationship between silica exposure and lung cancer mortality in German uranium miners, 1946-2003 Abstract: <strong>BACKGROUND: </strong>In 1996 and 2009, the International Agency for Research on Cancer classified silica as carcinogenic to humans. The exposure-response relationship between silica and lung cancer risk, however, is still debated. Data from the German uranium miner cohort study were used to further investigate this relationship.<br /><br /><strong>METHODS: </strong>The cohort includes 58677 workers with individual information on occupational exposure to crystalline silica in mg m(-3)-years and the potential confounders radon and arsenic based on a detailed job-exposure matrix. In the follow-up period 1946-2003, 2995 miners died from lung cancer. Internal Poisson regression with stratification by age and calendar year was used to estimate the excess relative risk (ERR) per dust-year. Several models including linear, linear quadratic and spline functions were applied. Detailed adjustment for cumulative radon and arsenic exposure was performed.<br /><br /><strong>RESULTS: </strong>A piecewise linear spline function with a knot at 10 mg m(-3)-years provided the best model fit. After full adjustment for radon and arsenic no increase in risk &lt;10 mg m(-3)-years was observed. Fixing the parameter estimate of the ERR in this range at 0 provided the best model fit with an ERR of 0.061 (95% confidence interval: 0.039, 0.083) &gt;10 mg m(-3)-years.<br /><br /><strong>CONCLUSION: </strong>The study confirms a positive exposure-response relationship between silica and lung cancer, particularly for high exposures.",
Arsenic,1025799,"Arsenite slows S phase progression via inhibition of cdc25A dual specificity phosphatase gene transcription Abstract: Arsenic acts as a toxicant, a carcinogen, and an effective chemotherapeutic agent, but its mechanisms of action are unclear. We have previously shown that treatment of U937 cells with 5 microM sodium arsenite inhibits cell cycle progression through each cell cycle phase, including S phase. Cdc25A dual specificity phosphatase controls entry into and progression through S phase by dephosphorylating sites of inhibitory phosphorylation on cyclin E-cdk2 (Thr14 and Tyr15). Immunoblotting reveals that a 3-h treatment of U937 cells with 5 microM sodium arsenite results in a dramatic decrease in cdc25A protein levels. Coimmunoprecipitation experiments confirm that cyclin E-cdk2 is more phosphorylated at Thr14 and Tyr15 in the presence of arsenite, and kinase activity assays reveal a decrease in cyclin E-associated cdk2 activity. Therefore, arsenite-dependent cdc25A depletion could contribute to S phase inhibition. There exists an S phase checkpoint known to be mediated by proteasomal cdc25A degradation. However, cycloheximide half-life assay reveals that cdc25A is actually stabilized in arsenite-treated cells. Real-time RT-PCR shows that cdc25A mRNA levels are substantially decreased with arsenite treatment, and actinomycin D half-life assay reveals no change in message stability. Decreased cdc25A message translation is shown by sucrose density gradient polysomal analysis to be an unlikely cause for the profound arsenite-dependent reduction in cdc25A protein levels. Studies are ongoing to establish the mechanism by which 5 microM arsenite decreases cdc25A message abundance, but we surmise that, given the lack of effect on mRNA stability, an inhibition of gene transcription is likely involved.",
Arsenic,1247278,"PI-3K/Akt signal pathway plays a crucial role in arsenite-induced cell proliferation of human keratinocytes through induction of cyclin D1 Abstract: Exposure of arsenite can induce hyperproliferation of skin cells, which is believed to play important roles in arsenite-induced carcinogenesis by affecting both promotion and progression stages. However, the signal pathways and target genes activated by arsenite exposure responsible for the proliferation remain to be defined. In the present study, we found that: (1) exposure of human keratinocytic HaCat cells to arsenite caused an increase in cell proliferation, which was significantly inhibited by pretreatment of wortmannin, a specific chemical inhibitor of PI-3K/Akt signal pathway; (2) arsenite exposure was also able to activate PI-3K/Akt signal pathway, which thereby induced the elevation of cyclin D1 expression level in both HaCat cells and human primary keratinocytes based on that inhibition of PI-3K/Akt pathway by either pretreatment of wortmannin or the transfection of their dominant mutants, significantly inhibited cyclin D1 expression upon arsenite exposure; (3) PI-3K/Akt pathway is implicated in arsenite-induced proliferation of HaCat cells through the induction of cyclin D1 because either knockdown of cyclin D1 by its siRNA or inhibition of PI-3K/Akt signal pathway by their dominant mutants markedly impaired the proliferation of HaCat cells induced by arsenite exposure. Taken together, we provide the direct evidence that PI-3K/Akt pathway plays a role in the regulation of cell proliferation through the induction of cyclin D1 in human keratinocytes upon arsenite treatment. Given the importance of aberrant cell proliferation in cell transformation, we propose that the activation of PI-3K/Akt pathway and cyclin D1 induction may be the important mediators of human skin carcinogenic effect of arsenite.",
Arsenic,711004,"Pathological, immunological and biochemical markers of subchronic arsenic toxicity in rats Abstract: Subchronic exposure to arsenic in rats was investigated to identify sensitive indicators of subclinical toxicity in rats. Immunological, pathological, and biochemical bioindicators were examined in rats exposed to arsenic in their drinking water. Juvenile male Wistar rats were allocated to four treatment groups receiving 0, 0.4, 4, and 40 ppm of arsenite in drinking water for 18 wks. Besides daily monitoring for clinical signs of adverse health effects, clinical biochemistry, B-cell-mediated and innate immune responses, plus gross, and histopathology were examined. In vitro tests of oxidative damage to basic cellular constituents, lipids, proteins, and nucleic acids, were measured using thiobarbituric acid reacting substances (TBARS) assays, protein carbonyl formation, and 8-hydroxydeoxyguanosine (8-OHdG), respectively. Clinical changes in the rats were limited to decreased feed and water intake in the high- (40 ppm) dose group (P &lt; 0.05), however, growth rate was not affected. Serum biochemical changes occurred in blood urea nitrogen, K(+), Cl(-), and alanine aminotransferase (ALT) from arsenic exposure. Immunotoxicity was evident through a dose-dependent suppression of the secondary antibody-mediated response to a T-cell-dependent antigen, keyhole limpet hemocyanin (KLH). Histopathology of the liver revealed marked fatty infiltration and vacuolization particularly evident in periacinar hepatocytes. This pattern of toxicopathology in the high-exposure group may be related to the significantly higher (P &lt; 0.05) oxidative stress, demonstrated through lipid peroxidation (TBARS assay) in the rats exposed to 40 ppm arsenite. The present study revealed that young, growing rats exposed to arsenic for 18 wks tolerated exposures up to 4 ppm. At higher doses, there was evidence of hepatotoxicity, humoral immunity was compromised, and an adverse effect on hepatic organelle and cell membranes was evident through a dose dependent increased in oxidative stress. (c) 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.",
Arsenic,2343453,"Increased lung and bladder cancer incidence in adults after in utero and early-life arsenic exposure Abstract: BACKGROUND: From 1958 to 1970, >100,000 people in northern Chile were exposed to a well-documented, distinct period of high drinking water arsenic concentrations. We previously reported ecological evidence suggesting that early-life exposure in this population resulted in increased mortality in adults from several outcomes, including lung and bladder cancer. METHODS: We have now completed the first study ever assessing incident cancer cases after early-life arsenic exposure, and the first study on this topic with individual participant exposure and confounding factor data. Subjects included 221 lung and 160 bladder cancer cases diagnosed in northern Chile from 2007 to 2010, and 508 age and gender-matched controls. RESULTS: ORs adjusted for age, sex, and smoking in those only exposed in early life to arsenic water concentrations of ?110, 110 to 800, and >800 ?g/L were 1.00, 1.88 [95% confidence interval (CI), 0.96-3.71], and 5.24 (3.05-9.00; P(trend) < 0.001) for lung cancer, and 1.00, 2.94 (1.29-6.70), and 8.11 (4.31-15.25; P(trend) < 0.001) for bladder cancer. ORs were lower in those not exposed until adulthood. The highest category (>800 ?g/L) involved exposures that started 49 to 52 years before, and ended 37 to 40 years before the cancer cases were diagnosed. CONCLUSION: Lung and bladder cancer incidence in adults was markedly increased following exposure to arsenic in early life, even up to 40 years after high exposures ceased. Such findings have not been identified before for any environmental exposure, and suggest that humans are extraordinarily susceptible to early-life arsenic exposure. IMPACT: Policies aimed at reducing early-life exposure may help reduce the long-term risks of arsenic-related disease.",
Arsenic,504545,"Effect of cysteine, methionine, ascorbic acid and thiamine on arsenic-induced oxidative stress and biochemical alterations in rats Abstract: Oxidative stress due to enhanced production of free radicals has been incriminated as one of the several mechanisms involved in arsenic-induced toxic effects in different organs. In the present study, ameliorative potential of certain amino acids like cysteine, methionine and vitamins like ascorbic acid and thiamine on some of the parameters indicative of oxidative stress in liver, kidney and blood and of hepatic and renal infliction was investigated in arsenic exposed rats. Rats were given 0 ppm (group I healthy controls) or 10 ppm arsenic in drinking water ad lib for a period of 12 weeks. During oral exposure to arsenic rats of different groups received daily oral dose of placebo, cysteine, methionine, ascorbic acid or thiamine at 25 mg/kg body weight. After the end of the experimental period, animals were sacrificed under light anesthesia and blood, liver and kidney were collected. Samples were processed for estimation of arsenic, biochemical parameters indicative of oxidative stress and hepatic and renal function. Arsenic exposure resulted in significantly (P < 0.05) higher accmulation of arsenic in blood, liver and kidney. It was associated with significant (P < 0.05) rise in lipid peroxide level and decrease in superoxide dismutase and catalase activities in liver and kidneys. However, alterations in biochemical parameters did not reach statistical (P > 0.05) significance. Treatment with vitamins and amino acids resulted in reversal of oxidative stress with significant (P < 0.05) decline in tissue arsenic burden. All the treatment produced tissue specific changes in lipid peroxide level, antioxidant enzyme activities and tissue arsenic burden. (c) 2005 Elsevier Ireland Ltd. All rights reserved.",
Arsenic,744879,"Reduction in total inorganic urinary arsenic and toenail arsenic with provision of bottled water Abstract: Background: Arsenic exposure is associated with increased cancer incidence. The purpose of this study was to measure the effectiveness of provision of bottled water in reducing inorganic urine and toenail arsenic concentrations in a population with elevated arsenic tap water levels. Methods: Urine, tap water, and toenail samples were collected from a random sample of nonsmoking adults (?18) residing in Ajo and Tucson, Arizona. After the baseline sample, Ajo subjects were provided with bottled water and were asked to use it for cooking, drinking, and food preparation. Results: At baseline, 40 subjects in Ajo and 32 subjects in Tucson provided urine and toenails. Total inorganic urinary arsenic (ppb) was higher in Ajo (29.1±20.4) than Tucson (11.0±12.0) (p<0.001). Creatinine-adjusted urinary total inorganic arsenic (microg/g) was also higher in Ajo (35.5±25.2) than Tucson (13.2±9.3) (p<0.001). Toenail arsenic concentrations (microg/g) were 0.51±0.72 in Ajo and 0.17±0.21 in Tucson (p<0.001). At follow up, 36 of the original 40 participants in Ajo again provided urine, water, and toenails. Mean urinary total inorganic arsenic dropped from 29.4±21.1 to 23.2±23.2 (p=0.026). Creatinine-adjusted urinary total inorganic arsenic was lower at follow-up (29.6±20.8) than baseline (34.8±27.4), although this change was not statistically significant (p=0.776). Toenail arsenic concentrations also decreased (0.49±0.68 vs. 0.26±0.19, p=0.061). Conclusion: Urinary and toenail arsenic were higher in Ajo, the town with higher tap water arsenic levels, than in Tucson. Provision of arsenic-free drinking water in Ajo reduced urinary total inorganic arsenic concentrations.",
Arsenic,628411,"Aneugenic effect of sodium arsenite on human lymphocytes in vitro: An individual susceptibility effect detected Abstract: Arsenic is a well known carcinogenic environmental pollutant although its mechanism of action remains unknown. Since alterations in chromosome segregation have been observed in individuals exposed to high concentrations of arsenic in the drinking water, the aneuploidogenic potential of arsenic was evaluated in vitro. Whole blood cultures were incubated for 72 h and treated with various concentrations of sodium arsenite for the last 24 h. Cells were harvested and samples were processed specially for aneuploidy evaluation. The number of chromosomes in 200 metaphases of first and second division cells was scored. A dose-related effect was observed: the highest concentration (10(-2) microM) induces 28.33% and 22.4% hyperploid cells in first and second division respectively and 29% tetraploid cells. The colchicine-like effect of arsenic was also evaluated. Mitotic arrest was evaluated in cultures treated for the last 2 h. Sodium arsenite can produce 40.24% and 12.93% of the colcemid effect (mitotic arrestant effect at 10(-2) microM and 10(-10) microM respectively). A different individual susceptibility effect was observed in both parameters and confirmed with the chromosome aberrations levels induced by arsenic in the same donors. Data indicate that sodium arsenite has an aneuploidogenic and a mitotic arrestant effect.",1
Arsenic,1797744,"Phosphorus improves arsenic phytoremediation by Anadenanthera peregrina by alleviating induced oxidative stress Abstract: Due to similarities in their chemical behaviors, studies examining interactions between arsenic (As)--in special arsenate--and phosphorus (P) are important for better understanding arsenate uptake, toxicity, and accumulation in plants. We evaluated the effects of phosphate addition on plant biomass and on arsenate and phosphate uptake by Anadenanthera peregrina, an important Brazilian savanna legume. Plants were grown for 35 days in substrates that received combinations of 0, 10, 50, and 100 mg kg(-1) arsenate and 0, 200, and 400 mg kg(-1) phosphate. The addition of P increased the arsenic-phytoremediation capacity of A. peregrina by increasing As accumulation, while also alleviating As-induced oxidative stress. Arsenate phytotoxicity in A. peregrina is due to lipid peroxidation, but not hydrogen peroxide accumulation. Added P also increased the activity of important reactive oxygen species-scavenging enzymes (catalase and ascorbate peroxidase) that help prevent lipid peroxidation in leaves. Our findings suggest that applying P represents a feasible strategy for more efficient As phytoremediation using A. peregrina.",
Arsenic,1347290,"Oxidative transformation of carbamazepine by manganese oxides Abstract: This study presents oxidative transformation of carbamazepine by synthetic manganese oxide (?-MnO2) as well as impact of variables including initial MnO2 loading, pH, coexisting metal ions, and humic acid (HA) on transformation. Manganese oxide (?-MnO2) was synthesized and stored in the form of suspension. The oxidative reactions were conducted in 50 mL polyethylene (PE) centrifuge tubes with constant pH maintained by buffers. The kinetic experiment was carried out in the solution of pH 2.72 containing 5.0 mg/L of carbamazepine and 130.5 mg/L of MnO2. Effects of initial MnO2 loading (0–130.5 mg/L), pH (2.72–8.58) and 0.01 M of coexisting solutes (metal ions and HA) on carbamazepine oxidation were also determined. Reaction kinetics indicated that carbamazepine was rapidly degraded in the first 5 min, and approximately 95 % of carbamazepine was eliminated within 60 min. The reaction exhibited pronounced pH dependence and increased with decreasing pH values. The transformation of carbamazepine was also accelerated with increasing MnO2 loadings. Coexisting metal ions competed with carbamazepine for reactive sites leading to reduced carbamazepine removal, and the inhibitive capacity followed the order of Mn2+?>?Fe3+?>?Ca2+???Mg2+. Presence of HA in aqueous solution caused a significant reduction on the magnitude of carbamazepine transformation. This study indicated that carbamazepine can be effectively degraded by ?-MnO2, and transformation efficiency was strongly dependent on reaction conditions. It suggests that amendment of soil with MnO2 be a potential alternative to solve carbamazepine pollution.",
Arsenic,1453806,"Aberrant overexpression of FOXM1 transcription factor plays a critical role in lung carcinogenesis induced by low doses of arsenic Abstract: Environmental or occupational exposure to low doses of arsenic induces a series of health problems including cancer. The molecular events in arsenic-induced carcinogenicity remain to be defined. In the NuLi-1 immortalized human lung epithelial cell line with p53 and pRb deficiency, exposure to low doses of arsenic trioxide for 72?h promoted cell proliferation and upregulated the gene transcription levels of FOXM1, CDC6, CDC25A, and cyclin D1, which are both critical cell cycle regulatory genes and proto-oncogenes. Continuous in vitro exposure to 1?µM arsenic trioxide for 34 wks induced malignant cell transformation, as evidenced by enhanced anchorage-independent cell growth. The expression of FOXM1, CDC6, CDC25A, and Cyclin D1 was dynamically elevated at the gene transcription and protein levels in the process of cell transformation. The carcinogenic ability of transformed cell colonies coincides with the expression levels of FOXM1 in in vitro anchorage-independent growth assays and in vivo tumor xenograft formation assays. In reverse, the knockdown of FOXM1 in lung adenocarcinoma A549 cells or arsenic-transformed NuLi-1 cells significantly decreased anchorage-independent cell growth and tumor xenograft formation. The transformed NuLi-1 cells showed genomic instability in the form of copy number variation (CNV) at chromosome 1, 5, 6, 18, and 20, but not loss of heterozygosity (LOH). These results showed for the first time that chronic exposure to low doses of arsenic trioxide promoted lung carcinogenicity, in part by aberrantly upregulating FOXM1 and its associated oncogenes, when the tumor suppressor genes p53 and pRb were inactivated. © 2012 Wiley Periodicals, Inc.",
Arsenic,1016845,"Regulation of cytoplasmic stress granules by apoptosis-inducing factor Abstract: Stress granules (SG) are dynamic cytoplasmic foci in which stalled translation initiation complexes accumulate. In conditions of acute cellular redox, stress cells manipulated to lose the expression of apoptosis-inducing factor (AIF) nucleate SG signature proteins (e.g. TIA-1, PABP1) more efficiently than AIF-positive controls. AIF also inhibited SG formation induced by the RasGAP-associated endoribonuclease G3BP. Retransfection of mouse AIF into cells subjected to human AIF-specific siRNA revealed that only AIF imported into mitochondria could repress SGs and that redox-active domains of AIF, which are dispensable for its apoptogenic action, were required for SG inhibition. In response to oxidative stress, AIF-negative cells were found to deplete non-oxidized glutathione more rapidly than AIF-expressing cells. Exogenous supplementation of glutathione inhibited SG formation elicited by arsenate or G3BP. Together, these data suggest that the oxidoreductase function of AIF is required for the maintenance of glutathione levels in stress conditions and that glutathione is a major regulator of SG.",
Arsenic,1020013,"Flow analysis-hydride generation-Fourier transform infrared spectrometry. A new analytical technique for the simultaneous determination of antimony, arsenic and tin Abstract: The combination of flow analysis (FA), hydride generation (HG) and Fourier transform infrared (FTIR) spectrometry is proposed as a novel and powerful analytical technique for the individual and simultaneous determination of antimony, arsenic and tin in aqueous samples. The analytes were transformed into the volatile hydride form by on-line reaction with sodium tetrahydroborate in acidic medium. The gaseous analyte hydrides [M(n)H(m), (g)] generated, were transported by means of a carrier gas stream inside the IR gas cell and the corresponding FTIR spectrum was acquired in a continuous mode. The 1893, 1904 and 2115 cm(-1) bands of the SbH3, SnH4, and AsH3 were selected for the determination of antimony, tin and arsenic, respectively. The limit of detection (3sigma) obtained by using a short-path (10 cm) IR gas cell were 0.25, 0.30 and 1.2 mg l(-1) for the determination of antimony, tin and arsenic, respectively; while the precision (relative standard deviation, RSD, n 5) found from a standard solution containing 50 mg l(-1) of each element was, in all cases, less than 0.3%. However, the use of a long-path (7.25 m) IR gas cell improved the figures of merit (sensitivity, limits of detection and quantification) nearly 60-fold. The effect of the main experimental and instrumental variables, such as acidic media, sodium tetraborohydrate concentration, nitrogen flow rate, nominal resolution and the scan accumulation on the analytical signals of the antimony, tin and arsenic hydrides, were studied. Further, the potential of the proposed technique for the simultaneous determination of these elements was tested, analyzing synthetic samples containing different amounts of Sb, Sn and As.",
Arsenic,1337922,"Determination of bioaccumulation of heavy metals and selenium in tissues of brown trout salmo trutta macrostigma (Duméril, 1858) from Munzur Stream, Tunceli, Turkey Abstract: The objective of the present work was to determine the bioaccumulation of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), uranium (U) and selenium (Se) in gill, liver, and muscle tissues of the fresh water fish Salmo trutta macrostigma (Duméril, 1858) in Munzur Stream, Tunceli, Turkey. The highest concentrations of U (1.83 ?g kg(-1)), Pb (119.84 ?g kg(-1)) and Se (1.31 ?g kg(-1)) were recorded in the gills of S. t. macrostigma. Concentrations of As (46.27 ?g kg(-1)), Cd (109.19 ?g kg(-1)), Hg (16.40 ?g kg(-1)), Cu (18.19 ?g kg(-1)) were recorded at highest levels in the liver. The results showed that there were significant differences in concentrations of As, Cd, Cu, Pb, Se, U and Hg in gill, liver and muscle tissue (p &lt; 0.05). Heavy metals were within the edible parts of the investigated fish were in the permissible safety levels for human uses.",
Arsenic,1252127,"Cell-nuclear accumulation of 72-kDa stress protein induced by dimethylated arsenics Abstract: The induction and subsequent intracellular distribution of the 72-kDa heat shock (stress) protein (Hsp72) by exposure of cultured human alveolar (L-132) cells to dimethylarsinic acid (DMAA), a main metabolite of inorganic arsenics in mammals, were examined. A significant induction of Hsp72 in the cells was observed by exposure to 10mM DMAA for 6 h. The induction was similar to the case by arsenite for 6 h or by heat treatment at 42 degrees C for 3h. However, the nuclear distribution of Hsp72 differed greatly between DMAA and 42 degrees C treatment or arsenite exposure, i.e., Hsp72 induced by exposure to DMAA accumulated not only in the nucleoli but also in the nucleoplasm, whereas that by 42 degrees C or arsenite exposure did not accumulate in the nucleoplasm. Furthermore, the Hsp72 accumulated in the nucleus by DMAA exposure hardly diffused with the addition of ATP, suggesting that the DMAA-induced Hsp72 strongly binds to some macromolecules in the nucleus. The fact that Hsp72 induced by DMAA exposure accumulated in the nucleus of the cells may reflect a protective response toward the nucleus-specific damaging action of dimethylarsenics.",
Arsenic,628141,"Mouse skin tumor promotion by sodium arsenate is associated with enhanced PCNA expression Abstract: Drinking water contamination by arsenicals remains a major public health problem in many parts of the world more particularly in India and Bangladesh. Despite arsenic being a health hazard and implicated in human carcinogenesis, the experimental evidence available is much limited even now and the mechanisms involved during carcinogenesis and tumor promotions are not clear. Accordingly, in this study, we have studied the tumor promoter effects of sodium arsenate on mouse skin tumor promoter model system using 9,10-dimethyl-1,2-benzanthracene (DMBA) as a initiating carcinogen. Our studies showed development of papillomas on mice skin treated with only DMBA. However, mice treated with DMBA on skin and administered arsenate (As) in drinking water showed development of well differentiated squamous cell carcinomas. Further, both by immunohistochemistry and western blotting analysis studies higher levels of proliferating cell nuclear antigen (PCNA) was observed in mice treated with DMBA plus arsenate compared to only DMBA treated group. PCNA is known to be associated with S phase and DNA replication of the cell cycle. The plain controls and arsenate controls did not show significant difference either in tumor development or in PCNA levels. The present study demonstrates mouse skin tumor promoting effect of arsenate which seems to be associated with abnormal cell proliferation as indicated by higher levels of PCNA expression.",
Arsenic,627677,"Exit from arsenite-induced mitotic arrest is p53 dependent Abstract: BACKGROUND: Arsenic is both a human carcinogen and a chemotherapeutic agent, but the mechanism of neither arsenic-induced carcinogenesis nor tumor selective cytotoxicity is clear. Using a model cell line in which p53 expression is regulated exogenously in a tetracycline-off system (TR9-7 cells) , our laboratory has shown that arsenite disrupts mitosis and that p53-deficient cells [p53(-)], in contrast to p53-expressing cells [p53(+)], display greater sensitivity to arsenite-induced mitotic arrest and apoptosis. OBJECTIVE: Our goal was to examine the role p53 plays in protecting cells from arsenite-induced mitotic arrest. METHODS: p53(+) and p53(-) cells were synchronized in G2 phase using Hoechst 33342 and released from synchrony in the presence or absence of 5 microM sodium arsenite. RESULTS: Mitotic index analysis demonstrated that arsenite treatment delayed exit from G2 in p53(+) and p53(-) cells. Arsenite-treated p53(+) cells exited mitosis normally, whereas p53(-) cells exited mitosis with delayed kinetics. Microarray analysis performed on mRNAs of cells exposed to arsenite for 0 and 3 hr after release from G2 phase synchrony showed that arsenite induced inhibitor of DNA binding-1 (ID1) differentially in p53(+) and p53(-) cells. Immunoblotting confirmed that ID1 induction was more extensive and sustained in p53(+) cells. CONCLUSIONS: p53 promotes mitotic exit and leads to more extensive ID1 induction by arsenite. ID1 is a dominant negative inhibitor of transcription that represses cell cycle regulatory genes and is elevated in many tumors. ID1 may play a role in the survival of arsenite-treated p53(+) cells and contribute to arsenic carcinogenicity.",
Arsenic,1353596,Use of an Adsorption Process for Purification of Pollock-Oil-Based Biodiesel Comprises Methyl Esters Abstract: ,
Arsenic,627109,"Chronic arsenic toxicity: Clinical features, epidemiology, and treatment: Experience in West Bengal Abstract: Chronic arsenic toxicity due to drinking arsenic-contaminated water has been one of the worst environmental health hazards affecting eight districts of West Bengal since the early eighties. Detailed clinical examination and investigation of 248 such patients revealed protean clinical manifestations of such toxicity. Over and above hyperpigmentation and keratosis, weakness, anaemia, burning sensation of eyes, solid swelling of legs, liver fibrosis, chronic lung disease, gangrene of toes, neuropathy, and skin cancer are some of the other manifestations. A cross-sectional survey involving 7683 participants of all ages was conducted in an arsenic-affected region between April 1995 and March 1996. Out of a population of 7683 surveyed, 3467 and 4216 people consumed water containing As below and above 0.05 mg/L, respectively. Except pain abdomen the prevalence of all other clinical manifestations tested (e.g., pigmentation, keratosis, hepatomegaly, weakness, nausea, lung disease and neuropathy) were found to be significantly higher in As exposed people (water As > 0.05 mg/L) compared to control population (water As level < 0.05 mg/L). The prevalence of pigmentation and keratosis, hepatomegaly, chronic respiratory disease and weakness rose significantly with increasing arsenic concentrations in drinking water. The respiratory effects were most pronounced in individuals with high arsenic water concentrations who also had skin lesion. Therapy with chelating agent DMSA was not found to be superior to placebo effect. However, therapy with DMPS caused significant improvement of clinical condition of chronic arsenicosis patients as evidenced by significant reduction of total clinical scores from 8.90 +/- 2.84 to 3.27 +/- 1.73; p < 0.0001. Efficacy of specific chelation therapy for patients suffering from chronic As toxicity has further need to be fully substantiated. However, supportive treatment could help in reducing many symptoms of the patients. Treatment in hospital with good nutritious diet has been found to reduce symptom score in a subset of placebo treated patients in West Bengal during the course of DMSA and DMPS trial. People should be advised to stop drinking As contaminated water or exposure to As from any other source. The various clinical manifestations should be treated symptomatically.",
Arsenic,1024573,"Concurrent subacute exposure to arsenic through drinking water and malathion via diet in male rats: effects on hepatic drug-metabolizing enzymes Abstract: Arsenic is a known global groundwater contaminant, while malathion is one of the most widely used pesticides in agriculture and public health practices in the world. Here, we investigated whether repeated exposure to arsenic at the groundwater contamination levels and to malathion at sublethal levels exerts adverse effects on the hepatic drug-metabolizing system in rats, and whether concurrent exposure is more hazardous than the single agent. Male Wistar rats were exposed daily to 4 or 40 ppm of arsenic via drinking water, 50 or 500 ppm of malathion-mixed feed and in a similar fashion co-exposed to 4 ppm of arsenic and 50 ppm of malathion or 40 ppm of arsenic and 500 ppm of malathion for 28 days. At term, toxicity was assessed by evaluating changes in body weight, liver weight, levels of cytochrome P(450) (CYP), cytochrome b (5) and microsomal and cytosolic proteins, and activities of aminopyrine-N-demethylase (ANDM), aniline-P-hydroxylase (APH), glutathione-S-transferase (GST) and uridine diphosphate glucuronosyltransferase (UGT) in liver. Arsenic and malathion alone did not alter body weight and liver weight, but these were significantly decreased in both the co-exposed groups. These treatments decreased the activities of ANDM and APH and the levels of liver microsomal and cytosolic proteins, increased GST activity and had no effect on UGT activity. The effects of exposure to low-dose and high-dose combinations on the activities of either phase I or phase II drug-metabolizing enzymes and protein content were mostly similar to that produced by the respective low and high dose of either arsenic or malathion, except APH activity. The effect of arsenic (40 ppm) on APH activity was partially, but significantly, inhibited by malathion (500 ppm). Results indicate that the body or liver weights and the biochemical parameters were differentially affected in male rats following concurrent subacute exposure to arsenic and malathion, with the co-exposure appearing more hazardous to physical variables based on body or liver weights whilst producing biochemical changes comparable to those caused by the individual agents. From these findings, no specific toxicological interaction between arsenic and malathion can be conclusively generalized.",
Arsenic,1017386,"Involvement of N-6 adenine-specific DNA methyltransferase 1 (N6AMT1) in arsenic biomethylation and its role in arsenic-induced toxicity Abstract: <strong>BACKGROUND: </strong>In humans, inorganic arsenic (iAs) is metabolized to methylated arsenical species in a multistep process mainly mediated by arsenic (+3 oxidation state) methyltransferase (AS3MT). Among these metabolites is monomethylarsonous acid (MMAIII), the most toxic arsenic species. A recent study in As3mt-knockout mice suggests that unidentified methyltransferases could be involved in alternative iAs methylation pathways. We found that yeast deletion mutants lacking MTQ2 were highly resistant to iAs exposure. The human ortholog of the yeast MTQ2 is N-6 adenine-specific DNA methyltransferase 1 (N6AMT1), encoding a putative methyltransferase.<br /><br /><strong>OBJECTIVE: </strong>We investigated the potential role of N6AMT1 in arsenic-induced toxicity.<br /><br /><strong>METHODS: </strong>We measured and compared the cytotoxicity induced by arsenicals and their metabolic profiles using inductively coupled plasma-mass spectrometry in UROtsa human urothelial cells with enhanced N6AMT1 expression and UROtsa vector control cells treated with different concentrations of either iAsIII or MMAIII.<br /><br /><strong>RESULTS: </strong>N6AMT1 was able to convert MMAIII to the less toxic dimethylarsonic acid (DMA) when overexpressed in UROtsa cells. The enhanced expression of N6AMT1 in UROtsa cells decreased cytotoxicity of both iAsIII and MMAIII. Moreover, N6AMT1 is expressed in many human tissues at variable levels, although at levels lower than those of AS3MT, supporting a potential participation in arsenic metabolism in vivo.<br /><br /><strong>CONCLUSIONS: </strong>Considering that MMAIII is the most toxic arsenical, our data suggest that N6AMT1 has a significant role in determining susceptibility to arsenic toxicity and carcinogenicity because of its specific activity in methylating MMAIII to DMA and other unknown mechanisms.",
Arsenic,2345695,"Protective effect of a laser-induced sub-lethal temperature rise on RPE cells from oxidative stress Abstract: Recently introduced new technologies that enable temperature-controlled laser irradiation on the RPE allowed us to investigate temperature-resolved RPE cell responses. In this study we aimed primarily to establish an experimental setup that can realize laser irradiation on RPE cell culture with the similar temperature distribution as in the clinical application, with a precise time/temperature history. With this setup, we conducted investigations to elucidate the temperature-dependent RPE cell biochemical responses and the effect of transient hyperthermia on the responses of RPE cells to the secondary-exposed oxidative stress. Porcine RPE cells cultivated in a culture dish (inner diameter = 30 mm) with culture medium were used, on which laser radiation (? = 1940 nm, spot diameter = 30 mm) over 10 s was applied as a heat source. The irradiation provides a radially decreasing temperature profile which is close to a Gaussian shape with the highest temperature in the center. Power setting for irradiation was determined such that the peak temperature (Tmax) in the center of the laser spot at the cells reaches from 40 °C to 58 °C (40, 43, 46, 50, 58 °C). Cell viability was investigated with ethidium homodimer III staining at the time points of 3 and 24 h following laser irradiation. Twenty four hours after laser irradiation the cells were exposed to hydrogen peroxide (H2O2) for 5 h, followed by the measurement of intracellular glutathione, intracellular 4-hydroxynonenal (HNE) protein adducts, and secreted vascular endothelial growth factor (VEGF). The mean temperature threshold for RPE cell death after 3 h was found to be around 52 °C, and for 24 h around 50 °C with the current irradiation setting. A sub-lethal preconditioning on Tmax = 43 °C significantly induced the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, and decreased H2O2-induced increase of intracellular 4-HNE protein adducts. Although sub-lethal hyperthermia (Tmax = 40 °C, 43 °C, and 46 °C) caused a slight increase of VEGF secretion in 6 h directly following irradiation, secondary exposed H2O2-induced VEGF secretion was significantly reduced in the sub-lethally preheated groups, where the largest effect was seen following the irradiation with Tmax = 43 °C. In summary, the current results suggest that sub-lethal thermal laser irradiation on the RPE at Tmax = 43 °C for 10 s enhances cell defense system against oxidative stress, with increasing the GSH/GSSG ratio. Together with the results that the decreased amount of H2O2-induced 4-HNE in sub-lethally preheated RPE cells was accompanied by the lower secretion of VEGF, it is also strongly suggested that the sub-lethal hyperthermia may modify RPE cell functionality to protect RPE cells from oxidative stress and associated functional decrease, which are considered to play a significant role in the pathogenesis of age-related macular degeneration and other chorioretinal degenerative diseases.",
Arsenic,1340118,"Involvement of RpoN in regulating bacterial arsenite oxidation Abstract: In this study with the model organism Agrobacterium tumefaciens, we used a combination of lacZ gene fusions, reverse transcriptase PCR (RT-PCR), and deletion and insertional inactivation mutations to show unambiguously that the alternative sigma factor RpoN participates in the regulation of As(III) oxidation. A deletion mutation that removed the RpoN binding site from the aioBA promoter and an aacC3 (gentamicin resistance) cassette insertional inactivation of the rpoN coding region eliminated aioBA expression and As(III) oxidation, although rpoN expression was not related to cell exposure to As(III). Putative RpoN binding sites were identified throughout the genome and, as examples, included promoters for aioB, phoB1, pstS1, dctA, glnA, glnB, and flgB that were examined by using qualitative RT-PCR and lacZ reporter fusions to assess the relative contribution of RpoN to their transcription. The expressions of aioB and dctA in the wild-type strain were considerably enhanced in cells exposed to As(III), and both genes were silent in the rpoN::aacC3 mutant regardless of As(III). The expression level of glnA was not influenced by As(III) but was reduced (but not silent) in the rpoN::aacC3 mutant and further reduced in the mutant under N starvation conditions. The rpoN::aacC3 mutation had no obvious effect on the expression of glnB, pstS1, phoB1, or flgB. These experiments provide definitive evidence to document the requirement of RpoN for As(III) oxidation but also illustrate that the presence of a consensus RpoN binding site does not necessarily link the associated gene with regulation by As(III) or by this sigma factor.",
Arsenic,1519245,"Low dose and long term toxicity of sodium arsenite caused caspase dependent apoptosis based on morphology and biochemical character Abstract: OBJECTIVE: Although arsenite is toxic it is currently recommended for the treatment of malignancies. In this study the effects of sub-micromolar concentrations of sodium arsenite on the viability, morphology and mechanism of cell death of rat bone marrow mesenchymal stem cells (BMCs) over 21 days was investigated. MATERIALS AND METHODS: In this experimental study, BMCs were extracted in Dulbecco's Modified Eagles Medium (DMEM) containing 15% of fetal bovine serum (FBS) and expanded till the 3(rd) passage. The cells were treated with 1, 10, 25, 50, 75 and 100 nM of sodium arsenite for 21 days and the viability of the cells estimated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyl tetrazolium (MTT) and trypan blue staining. Cells were then treated with the selected dose (25 nM) of sodium arsenite to determine their colony forming ability (CFA) and population doubling number (PDN). Morphology of the cells was studied using florescent dyes, and the integrity of the DNA was investigated using the comet assay and agarose gel electrophoresis. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and the caspase 3 assay were then applied to understand the mechanism of cell death. Data was analyzed using one way ANOVA, Tukey test. RESULTS: A significant reduction of viability, PDN and CFA was found following treatment of BMCs with 25 nM sodium arsenite (p<0.05). Cytoplasm shrinkage and a significant decrease in the diameter of the nuclei were also seen. Comet assay and agarose gel electrophoresis revealed DNA breakage, while positive TUNEL and activated caspase 3 confirmed the apoptosis. CONCLUSION: A low concentration of sodium arsenite (25 nM) caused reduction of viability due to induction of apoptosis. Therefore, long term exposure to low dose of this chemical may have unwanted effects on BMCs.",
Arsenic,1240716,"Regression estimator under inverse sampling to estimate arsenic contamination Abstract: The fate of arsenic introduced to the environment as a result of the natural and human activities is an important issue. Surveys of arsenic typically involve sampling from a large area. Measuring arsenic concentrations in samples is expensive, and any improvement in the survey design is welcome. One way to improve efficiency in sampling is to make use of auxiliary information. Surveys of environmental pollution can be classed as surveys of rare populations, where there is a large area with a small polluted subarea. The rare population has many zeroes, or low, values, and contaminated subareas have non-zero, or high, values. Regression estimators or ratio estimators are undefined for those samples containing only information from the non-rare (zero-value) subpopulation (i.e., the non-contaminated subpopulation) in simple random sampling. In this paper, we introduce the modified regression estimators and their associated variance estimators for sampling designs which are suitable for rare populations, such as general inverse sampling and inverse sampling with unequal selection probabilities. We conducted a simulation study on the real rare population arsenic contamination in Kurdistan. The simulation results showed that the modified regression estimators are more efficient than the previous estimators.",
Arsenic,1019668,"Molecular basis for effects of carcinogenic heavy metals on inducible gene expression Abstract: Certain forms of the heavy metals arsenic and chromium are considered human carcinogens, although they are believed to act through very different mechanisms. Chromium(VI) is believed to act as a classic and mutagenic agent, and DNA/chromatin appears to be the principal target for its effects. In contrast, arsenic(III) is considered nongenotoxic, but is able to target specific cellular proteins, principally through sulfhydryl interactions. We had previously shown that various genotoxic chemical carcinogens, including chromium (VI), preferentially altered expression of several inducible genes but had little or no effect on constitutive gene expression. We were therefore interested in whether these carcinogenic heavy metals might target specific but distinct sites within cells, leading to alterations in gene expression that might contribute to the carcinogenic process. Arsenic(III) and chromium(VI) each significantly altered both basal and hormone-inducible expression of a model inducible gene, phosphoenolpyruvate carboxykinase (PEPCK), at nonovertly toxic doses in the chick embryo in vivo and rat hepatoma H411E cells in culture. We have recently developed two parallel cell culture approaches for examining the molecular basis for these effects. First, we are examining the effects of heavy metals on expression and activation of specific transcription factors known to be involved in regulation of susceptible inducible genes, and have recently observed significant but different effects of arsenic(III) and chromium(VI) on nuclear transcription factor binding. Second, we have developed cell lines with stably integrated PEPCK promoter-luciferase reporter gene constructs to examine effects of heavy metals on promoter function, and have also recently seen profound effects induced by both chromium(VI) and arsenic(III) in this system. These model systems should enable us to be able to identify the critical cis (DNA) and trans (protein) cellular targets of heavy metal exposure leading to alterations in expression of specific susceptible genes. It is anticipated that such information will provide valuable insight into the mechanistic basis for these effects as well as provide sensitive molecular biomarkers for evaluating human exposure.",
Arsenic,1029553,"Structure-effect relationship in the down-regulation of glutaminase in cultured human cells by phenylarsenic compounds Abstract: Diphenylarsinic acid [DPAA(V)] was detected in ground water used as drinking water after a poisonous incident in Kamisu, Japan. An approach to define the target molecules of DPAA(V) with a high throughput analysis of proteins from cultured human cells demonstrated down-regulation of glutaminase C (GAC). GAC is a splicing variant of the kidney-type glutaminase (KGA) gene and has the enzyme activity of phosphate-activated glutaminase (PAG). To gain some insights into the mechanism of arsenic intoxication in Kamisu, the effects of various arsenic compounds, including arsenicals that were detected in ground water ([DPAA(V)], phenylarsonic acid [PAA(V)] and bis(diphenylarsine)oxide [BDPAO(III)]) and rice (phenylmethylarsinic acid [PMAA(V)]), were investigated for the expression of GAC and PAG activity. When cultured human HepG2 cells were incubated with arsenicals for 24h, the pentavalent phenylarsenic form of PAA(V) and PMAA(V) as well as DPAA(V) suppressed the expression of GAC protein and PAG activity in a concentration-dependent manner. On the other hand, the trivalent phenylarsenic form of BDPAO(III) had no suppressive effect on GAC and PAG. In addition, trivalent phenylarsenic compounds, such as the glutathione (GSH) conjugate of DPAA(V) [DPA-GS (III)] and triphenylarsine [TPA(III)], and the inorganic arsenics, iAs(V) and iAs(III), and methylated metabolites of inorganic arsenics, dimethylarsinic acid [DMA(V)] and dimethylarsinous acid [DMA(III)], had no suppressive effect on glutaminase. Likewise, methyl substituents of the hydroxyl groups of DPAA(V), PAA(V) and PMAA(V), diphenylmethylarsine oxide [DPMAO(V)] and phenyldimethylarsine oxide [PDMAO(V)], did not have any suppressive effects. These results suggest that pentavalent arsenic compounds with both phenyl groups and hydroxyl groups are effective in the suppression of glutaminase. In addition, the fact that it was only the arsenicals detected in Kamisu that were effective in suppressing glutaminase provides insights into the cause of the arsenic intoxication at Kamisu.",
Arsenic,1519213,"[Analysis of the natural vibration frequency test method to obtain the modulus of elasticity of wood structural components] Abstract: There are several techniques to characterize the elastic modulus of wood and those currently using the natural frequencies of vibration stand out as they are non-destructive techniques, producing results that can be repeated and compared over time. This study reports on the effectiveness of the testing methods based on the natural frequencies of vibration versus static bending to obtain the elastic properties of reforested structural wood components usually employed in civil construction. The following components were evaluated: 24 beams of Eucalyptus sp. with nominal dimensions (40 x 60 x 2.000 mm) and 14 beams of Pinus oocarpa with nominal dimensions (45 x 90 x 2.300 mm) both without treatment; 30 boards with nominal dimensions (40 x 240 x 2.010 mm) and 30 boards with nominal dimensions (40 x 240 x 3.050 mm), both of Pinus oocarpa and with chromate copper arsenate (CCA) preservative treatment. The results obtained in thiswork show good correlation when compared to the results obtained by the static bending mechanical method, especially when applying the natural frequency of longitudinal vibration. The use of longitudinal frequency was reliable and practical, therefore recommended for determining the modulus of elasticity of wood structural elements. It was also found that no specific support is needed for the specimens using the longitudinal frequency, as well as no previous calibrations, reducing the execution time and enabling to test many samples.",
Arsenic,628666,"Effect of hepatic methyl donor status on urinary excretion and DNA damage in B6C3F1 mice treated with sodium arsenite Abstract: This study evaluated the effect of hepatic methyl donor status on the ability of sodium arsenite (2.5, 5.0 and 10.0 mg/kg) administered by gavage once or on four consecutive days to induce DNA damage in male B6C3F1 mice. Maintenance on a choline-deficient (CD) diet prior to treatment resulted in mice with hepatic methyl donor deficiency (HMDD) and altered arsenical metabolism, as demonstrated by a decreased total urinary excretion of inorganic and organic arsenicals. The alkaline (pH > 13) Single Cell Gel (SCG) assay was used to evaluate for the induction of DNA damage (single strand breaks, alkali labile sites, DNA crosslinking) in blood leukocytes, liver parenchymal cells, and cells sampled from bladder, lung, and skin, while the bone marrow erythrocyte micronucleus (MN) assay was used to assess for the induction of chromosomal damage in bone marrow cells. Treatment with sodium arsenite once or four times induced a significant decrease in DNA migration (indicative of DNA crosslinking) in bladder and liver parenchymal cells of hepatic methyl donor sufficient (HMDS) mice, but in skin cells of HMDD mice. Both HMDD and HMDS mice exhibited a significant increase in the frequency of micronucleated polychromatic erythrocytes (MN-PCE) in bone marrow following four, but not following one, treatments. However, the positive response occurred at a lower dose for HMDS mice and, in these mice, bone marrow toxicity, as demonstrated by a significant reduction in the percentage of PCE, was present also. These results indicate that hepatic methyl donors deficiency significantly decreases the total urinary excretion of orally administered sodium arsenite and markedly modulates target organ arsenic-induced DNA damage, with an apparent shift from liver and bladder to skin.",
Arsenic,1794731,Arsenic in Marina Sediments from the Mediterranean Coast: Speciation in the Solid Phase and Occurrence of Thioarsenates Abstract: ,
Arsenic,2345856,"Interspecies variation in DNA damage induced by pollution Abstract: The choice of a suitable species to translate pollution signals into a quantitative monitor is a fundamental step in biomonitoring plans. Here we present the results of three years of biomonitoring at a new coal power plant in central Italy using three different aquatic and terrestrial wildlife species in order to compare their reliability as sentinel organisms for genotoxicity. The comet assay was applied to the common land snail Helix spp., the lagoon fish Aphanius fasciatus, and the green frog Rana esculenta sampled in the area potentially exposed to the impact of the power station. The tissue concentration of some expected pollutants (As, Cd, Ni, Pb, Cr) was analysed in parallel samples collected in the same sampling sites. The three species showed different values in the comet assay (Tail Intensity) and different accumulation profiles of heavy metals. Aphanius fasciatus showed an increasing genotoxic effect over time that paralleled the temporal increase of the heavy metals, especially arsenic, and the highest correlation between heavy metals and DNA damage. Helix spp. showed levels of damage inversely related to the distance from the source of pollution and in partial accordance with the total accumulation of trace elements. On the contrary, Rana esculenta showed a low capability to accumulate metals and had inconsistent results in the comet test. The fish appeared to be the most efficient and sensitive species in detecting chemical pollution. Overall, both the fish and the snail reflected a trend of increasing pollution in the area surrounding the power plant across time and space",
Arsenic,1070327,"Identification of an S-adenosylmethionine (SAM) dependent arsenic methyltransferase in Danio rerio Abstract: Arsenic methylation is an important cellular metabolic process that modulates arsenic toxicity and carcinogenicity. Biomethylation of arsenic produces a series of mono-, di- and tri-methylated arsenic metabolites that can be detected in tissues and excretions. Here we report that zebrafish exposed to arsenite (As(III)) produces organic arsenicals, including MMA(III), MMA(V) and DMA(V) with characteristic tissue ratios, demonstrating that an arsenic methylation pathway exists in zebrafish. In mammals, cellular inorganic arsenic is methylated by a SAM-dependent arsenic methyltransferase, AS3MT. A zebrafish arsenic methyltransferase homolog, As3mt, was identified by sequence alignment. Western blotting analysis showed that As3mt was universally expressed in zebrafish tissues. Prominent expression in liver and intestine correlated with methylated arsenic metabolites detected in those tissues. As3mt was expressed in and purified from Escherichiacoli for in vitro functional studies. Our results demonstrated that As3mt methylated As(III) to DMA(V) as an end product and produced MMA(III) and MMA(V) as intermediates. The activity of As3mt was inhibited by elevated concentrations of the substrate As(III) as well as the metalloid selenite, which is a well-known antagonistic micronutrient of arsenic toxicity. The activity As3mt was abolished by substitution of either Cys160 or Cys210, which corresponds to conserved cysteine residues in AS3MT homologs, suggesting that they are involved in catalysis. Expression in zebrafish of an enzyme that has a similar function to human and rodent orthologs in catalyzing intracellular arsenic biomethylation validates the applicability of zebrafish as a valuable vertebrate model for understanding arsenic-associated diseases in humans.",
Arsenic,628054,"Thermodynamics of the As(III)-thiol interaction: arsenite and monomethylarsenite complexes with glutathione, dihydrolipoic acid, and other thiol ligands Abstract: Colorimetric (near-UV absorption spectroscopy) and calorimetric (isothermal titration calorimetry) methods have been used to quantify the equilibrium and thermodynamics of arsenite and monomethylarsenite (MMA) coordinating to glutathione (GSH) and the dithiols dimercaptosuccinic acid (DMSA), dihydrolipoic acid (DHLA), and dithiothreitol (DTT). We found that both arsenite and MMA form moderately stable complexes (beta = 10(6)-10(7)) with GSH; that arsenite forms a particularly stable 2:3 complex (beta approximately 10(18)) with the biological cofactor DHLA; that MMA has a somewhat higher affinity than arsenite for thiol ligands; and that entropic factors modulate the overall stability of As(III) complexes with thiols, which are favored by the exothermic formation of As(III)-thiolate bonds. The implications of these results for arsenic toxicity are discussed.",
Arsenic,2064203,"Natural montmorillonite induced photooxidation of As(III) in aqueous suspensions: Roles and sources of hydroxyl and hydroperoxyl/superoxide radicals Abstract: Photooxidation of arsenite(As(III)) in a suspension of natural montmorillonite under the irradiation of metal halide lamp (??313nm)has been investigated. The results showed that the natural montmorillonite induced the photooxidation of As(III) by generating hydroxyl radicals (HO) and hydroperoxyl/superoxide radicals (HO2/O2(-)). HO which was responsible for the As(III) photooxidation. Approximately 38% of HO was generated by the photolysis of ferric ions, and the formation of the remaining 62% was strongly dependent on the HO2/O2(-). The presence of free ironions (Fe(2+) and Fe(3+)), made significant contributions to the photogeneration of these reactive oxygen species (ROS). The photooxidation of As(III) in natural montmorillonite suspensions was greatly influenced by the pH values. The photooxidation of As(III) by natural montmorillonite followed the Langmuir-Hinshelwood equation. In addition, the photooxidation of As(III) could be enhanced by the addition of humic acid. This work demonstrates that photooxidation may be an important environmental process for the oxidation of As(III) and may be a way to remove As(III) from acidic surface water containing iron-bearing clay minerals.",
Arsenic,1019713,"Urinary arsenic species in Devon and Cornwall residents, UK. A pilot study Abstract: First void urine samples were collected from 24 residents in an area of past intense mining and smelting activity of arsenical ores. Seven samples were also taken from a control village. The arsenic species in the urine were separated and quantified with an HPLC-ICP-MS system equipped with a hydraulic high-pressure nebulizer. The detection limit for arsenic in urine using this system is 0.05 microgram dm-3. Creatinine was also determined for all samples to remove the influence of urine density and all results were expressed in microgram As g-1 creatinine. The results showed elevated levels of both organic and inorganic arsenic compounds in the 'exposed' population's urine when compared with those of the control group. The total As concentrations (less arsenobetaine) in the 'exposed' population were in the range 2.7-58.9 micrograms g-1 creatinine (mean 13.4, median 9.2 micrograms g-1) compared with the control group data range 2.5-5.3 micrograms g-1 (mean 4.2, median 4.7 micrograms g-1).",
Arsenic,1519207,"Arsenic and lead in juice: Apple, citrus, and apple-base Abstract: Exposure limits for arsenic and lead in drinking water have long been established by the U.S. Environmental Protection Agency and new regulations regarding the presence of these contaminants in bottled water went into effect in California in 2009. No comparable exposure limits or regulations are available, however, for juices and other beverages that may contain arsenic and lead. In the study described in this article, 20 apple juices (or ciders), 15 apple-containing juices, one grape, and one citrus juice were analyzed for arsenic and lead. Arsenic was detected in all juices while lead was detected in more than 94% of juices analyzed. Twelve samples (32%) demonstrated arsenic levels nearly at or above the drinking water exposure limit of 10 parts per billion. No juices contained lead above drinking water exposure limits. Expanding drinking water limits to include juices (and other frequently consumed beverages) would better protect consumers while regular testing of these juices would better inform consumers of the risks posed by specific juices and brands.",
Arsenic,2278950,"Assessment of peripheral skeletal muscle microperfusion in a porcine model of peripheral arterial stenosis by steady-state contrast-enhanced ultrasound and Doppler flow measurement Abstract: <strong>OBJECTIVE: </strong>Noninvasive measurement of peripheral muscle microperfusion could potentially improve diagnosis, management, and treatment of peripheral arterial disease (PAD) and thus improve patient care. Contrast-enhanced ultrasound (CEUS) as a noninvasive diagnostic tool allows quantification of muscle perfusion. Increasing data on bolus technique CEUS reflecting microperfusion are becoming available, but only limited data on steady-state CEUS for assessment of muscle microperfusion are available. Therefore, the aim of this study was to evaluate steady-state CEUS for assessment of peripheral muscle microperfusion in a PAD animal model.<br /><br /><strong>METHODS: </strong>In a porcine animal model, peripheral muscle microperfusion was quantified by steady-state CEUS replenishment kinetics (mean transit time [mTT] and wash-in rate [WiR]) of the biceps femoris muscle during intravenous steady-state infusion of INN-sulfur hexafluoride (SonoVue; Bracco, Geneva, Switzerland). In addition, macroperfusion was quantified at the external femoral artery with a Doppler flow probe. Peripheral muscle microperfusion and Doppler flow measurements were performed bilaterally at rest and under adenosine stress (70 ?g/kg body weight) before and after unilateral creation of a moderate external iliac artery stenosis.<br /><br /><strong>RESULTS: </strong>All measurements could be performed completely in 10 pigs. Compared with baseline measurements, peripheral muscle microperfusion decreased significantly during adenosine stress (rest vs adenosine stress: mTT, 7.8 ± 3.3 vs 21.2 ± 17.8 s, P = .0006; WiR, 58.4 ± 38.1 vs 25.3 ± 15.6 arbitrary units [a.u.]/s, P &lt; .0001; Doppler flow, 122.3 ± 31.4 vs 83.6 ± 28.1 mL/min, P = .0067) and after stenosis creation (no stenosis vs stenosis: mTT, 8.1 ± 3.1 vs 29.2 ± 18.0 s, P = .0469; WiR, 53.0 ± 22.7 vs 13.6 ± 8.4 a.u./s, P = .0156; Doppler flow, 124.2 ± 41.8 vs 65.9 ± 40.0 mL/min, P = .0313). After stenosis creation, adenosine stress led to a further significant decrease of peripheral muscle microperfusion but had no effect on macroperfusion (mTT, 29.2 ± 18.0 vs 56.3 ± 38.7 s, P = .0078; WiR, 13.6 ± 8.4 vs 6.0 ± 4.1 a.u./s, P = .0078; Doppler flow, 65.9 ± 40.0 vs 79.2 ± 29.6 mL/min, P = .8125). Receiver operating characteristic curves for the presence of inflow stenosis showed an excellent area under the curve of 0.93 for mTT at rest and 0.86 for Doppler flow.<br /><br /><strong>CONCLUSIONS: </strong>Peripheral muscle microperfusion measurement by steady-state CEUS with replenishment kinetics is feasible and allows detection of muscle microperfusion changes caused by vasodilative stress alone or in combination with a moderate inflow stenosis. Steady-state CEUS offers superior diagnostic performance compared with Doppler flow measurements. Therefore, steady-state CEUS may prove to be a useful tool in diagnosis of PAD and for evaluation of new therapies.",
Arsenic,1350266,Preparation of new base-aluminum-chloride-loaded fiber as adsorbent for fast removal of arsenic(V) from water Abstract: ,
Arsenic,734923,"Reduction in arsenic intake from water has different impacts on lung cancer and bladder cancer in an arseniasis endemic area in Taiwan Abstract: Excessive arsenic intake has a detrimental effect on human health, as reflected in an increase in cancer incidence. In an area on the southwest coast of Taiwan, arsenic intake from well water since the 1920s had caused an exceptionally high mortality from cancer. Municipal water has become available to people living in the arseniasis endemic area since the early 1970s. This study explored the impacts of reduction in arsenic intake from water on lung cancer and bladder cancer in the arseniasis endemic area in Taiwan.<br /><br /> Chart records of 23,013 patients diagnosed with bladder cancer and 93,633 patients with lung cancer from 1979 to 2003 were retrieved from the Taiwan Cancer Registry Center. We used the age-period-cohort model to study the changes in the incidence of lung cancer and bladder cancer in the arseniasis endemic area and the rest of Taiwan.<br /><br /> Three decades after municipal water supply to the arseniasis and black foot disease endemic area (BFDEA), we saw a marked decrease in the incidence of both bladder cancer and lung cancer in the area, especially for those in the later cohorts. The relative risk (RR) of getting a bladder cancer for people living in BFDEA when compared with those in the rest of Taiwan has dropped from 20 for the early cohorts to 5 for the late cohorts. As to lung cancer, the RR has decreased from 8 to between 1.5 and 2.<br /><br /> Reduction in arsenic intake from water has a positive impact on the incidence of both lung and bladder cancer; however, while RR for lung cancer has dropped to below 2, RR for bladder cancer remained at around 5. The difference may be because (1) there are other risk factors beside the well-water intake or (2) bladder cancer may have longer latency period for excessive arsenic exposure than lung cancer. More studies are required to understand the causes behind the difference in RR for these two types of cancer.",
Arsenic,1677549,"Associations of urinary metal concentrations and circulating testosterone in Chinese men Abstract: Toxicological studies have shown that metals directly or indirectly influence testosterone (T) production, but the data from humans is limited and inconsistent. The aim of this study is to examine the associations between urinary metal concentrations and circulating T in Chinese men. Urinary concentrations of 13 metals (arsenic, cadmium, cobalt, chromium, copper, iron, lead, manganese, molybdenum, mercury, nickel, selenium and zinc) and serum levels of T were analyzed in 118 men from an infertility clinic. Multivariable linear regression was used to assess the effect of metals exposure on T. Among the measured metals, the median urinary Zn (359.36?g/g creatinine) and Co (0.16?g/g creatinine) concentrations were the highest and the lowest, respectively. Significant dose-response relationships were found between decreased T and urinary Mn and Zn, even when considering multiple metals (both P for trend&lt;0.05). Our results indicate that elevated Mn and Zn are inversely associated with T production.",
Arsenic,1509340,Inorganic arsenic sorption by drinking-water treatment residual-amended sandy soil: effect of soil solution chemistry Abstract: ,
Arsenic,1597379,"Total and inorganic arsenic contents in some edible zingiberaceous rhizomes in Thailand Abstract: The arsenic accumulation in rhizomes of Zingiberaceous plants was determined by atomic absorption spectrometry interfaced with hydride generation system (HG-AAS). The raw herbal materials, rhizomes, were collected from different regions of Thailand between December 2011 and January 2012. Six well-known Zingiberaceous plants, 16 samples from each and a total of 96 samples, were analyzed Alpinia galanga (Khaa), Boesenbergia rotunda (Kra-chaai), Curcuma longa (Khamin-chan), Curcuma zedoaria (Khamin-oi), Zingiber cassumunar (Plai) and Zingiber officinale (Ginger). Concentrations of total arsenic based on dry weight were 92.4 ± 9.2, 103.5 ± 20.8, 61.7 ± 12.5, 89.8 ± 17.5, 106.7 ± 19.5 and 69.3 ± 11.8?ng/g, respectively and inorganic arsenic were 48.8 ± 7.0, 66.3 ± 12.7, 25.5 ± 5.0, 38.7 ± 4.7, 71.2 ± 11.6, and 38.5 ± 5.5?ng/g, respectively. Among these, Plai and Kra-chaai exhibited the highest levels of total arsenic and inorganic arsenic accumulation that remind consumers to be aware of excess consuming of these rhizomes. On the contrary, the lowest value found in Khamin-chan indicating natural dietary supplements and herbal medicines comprising Kamin-chan are safe from arsenic poison. All investigated amounts of total and inorganic arsenic were much lower than limits recommended by Thai Food and Drug Administration.",
Arsenic,627305,"Inhibition of DNA ligase activity by arsenite: A possible mechanism of its comutagenesis Abstract: We have previously shown that the inhibition of MNU-induced DNA repair by arsenite occurs after the incision step in Chinese hamster V79 cells. We now report that nuclear DNA ligase activity is inhibited after arsenite treatment and that the inhibited activity is mostly DNA ligase II. Both constitutive and MNU-inducible levels of DNA ligase II are inhibited. The addition of arsenite in vitro also indicates that DNA ligase II is more sensitive to arsenite inhibition than DNA ligase I. Since DNA ligase II is reported to be involved in the ligation step of excision repair, its inhibition by arsenite is a likely mechanism for the inhibition of DNA repair by arsenite and may account for the fact that arsenite acts as a comutagen with a number of different types of mutagens. The carcinogenicity of arsenite may also be a result of ligase inhibition.",
Arsenic,1355633,"The upper midwest health study: a case-control study of pesticide applicators and risk of glioma Abstract: <strong>BACKGROUND: </strong>An excess incidence of brain cancer in farmers has been noted in several studies. The National Institute for Occupational Safety and Health developed the Upper Midwest Health Study (UMHS) as a case-control study of intracranial gliomas and pesticide uses among rural residents. Previous studies of UMHS participants, using &quot;ever-never&quot; exposure to farm pesticides and analyzing men and women separately, found no positive association of farm pesticide exposure and glioma risks. The primary objective was to determine if quantitatively estimated exposure of pesticide applicators was associated with an increased risk of glioma in male and female participants.<br /><br /><strong>METHODS: </strong>The study included 798 histologically confirmed primary intracranial glioma cases (45?% with proxy respondents) and 1,175 population-based controls, all adult (age 18-80) non-metropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. The analyses used quantitatively estimated exposure from questionnaire responses evaluated by an experienced industrial hygienist with 25 years of work on farm pesticide analyses. Odds ratios (ORs) and 95?% confidence intervals (CIs) using unconditional logistic regression modeling were calculated adjusting for frequency-matching variables (10-year age group and sex), and for age and education (a surrogate for socioeconomic status). Analyses were separately conducted with or without proxy respondents.<br /><br /><strong>RESULTS: </strong>No significant positive associations with glioma were observed with cumulative years or estimated lifetime cumulative exposure of farm pesticide use. There was, a significant inverse association for phenoxy pesticide used on the farm (OR 0.96 per 10?g-years of cumulative exposure, CI 0.93-0.99). No significant findings were observed when proxy respondents were excluded. Non-farm occupational applicators of any pesticide had decreased glioma risk: OR 0.72, CI 0.52-0.99. Similarly, house and garden pesticide applicators had a decreased risk of glioma: OR 0.79, CI 0.66-0.93, with statistically significant inverse associations for use of 2,4-D, arsenates, organophosphates, and phenoxys.<br /><br /><strong>CONCLUSIONS: </strong>These results are consistent with our previous findings for UMHS of reported farm pesticide exposure and support a lack of positive association between pesticides and glioma.",
Arsenic,1020416,"Assessment of cancer risk and environmental levels of arsenic in New Hampshire Abstract: The Agency for Toxic Substances and Disease Registry (ATSDR) and the United States (US) Environmental Protection Agency (EPA) Office of Solid Waste and Emergency Response (OSWER) list arsenic as a major concern for Superfund sites and the environment at large. Arsenic is clearly linked to skin, bladder, and lung cancer occurrence in populations highly exposed to arsenic occupationally, medicinally, or through contaminated drinking water (Agency for Toxic Substances and Disease Registry, 1999; IARC, 1987). While these studies have identified important adverse health effects, they cannot provide risk information at lower levels of exposure such as those commonly found in the US. Additionally, precise measurement of exposure is critical to assessing risk in populations consuming relatively trace amounts of arsenic. In New Hampshire, domestic wells serve roughly 40% of the population, and about 10% of these contain arsenic concentrations in the controversial range of 10 to 50 micrograms/l. New Hampshire, along with other states in New England, has among the highest bladder cancer mortality rates in the country. Therefore, we are conducting a population-based epidemiologic study in New Hampshire (1) to assess the risk of skin and bladder cancer associated with arsenic exposure in a US population, (2) to evaluate methods of quantifying individual exposure to arsenic at low to moderate levels, and (3) to explore alternative models of determining the dose-response relationship at the lower end of exposure. Our findings to date indicate that toenail arsenic concentrations are a reliable, long-term biomarker of total arsenic exposure and reflect arsenic intake by drinking water containing 1 microgram/l or more. We found that urinary arsenic cannot be detected consistently in a population for which drinking water arsenic is primarily below 50 micrograms/l. Lastly, our data suggest that use of a biologic marker along with alternative statistical approaches may aid detection of the levels at which arsenic may affect cancer occurrence in the US.",
Arsenic,628059,"Low-level population exposure to inorganic arsenic in the United States and diabetes mellitus: A reanalysis Abstract: BACKGROUND: Although studies have reported associations between high concentrations of ingested inorganic arsenic and diabetes mellitus, there is no evidence of this association at low exposures. However, a well-publicized study (JAMA. 2008;300:814-822) recently produced an extraordinary finding of a more than 3-fold increase in diabetes at low concentrations of urinary arsenic. This potentially affects 40 million adults in the United States. METHODS: We used the same cross-sectional data on urinary arsenic and type 2 diabetes mellitus in 795 adults from the 2003-2004 National Health and Nutrition Examination Survey to assess this evidence. RESULTS: As in the earlier study, we found an odds ratio (OR) near 1.0 for diabetes, comparing the 80th versus 20th percentiles of urinary total arsenic (OR = 0.88 [95% confidence interval = 0.39-1.97]). This OR increased to above 3.0 when urinary arsenobetaine was added to the logistic risk model. However, this high OR was a statistical artifact because arsenobetaine, which is ingested from fish and is essentially nontoxic, is a part of measured total urinary arsenic. These 2 variables are highly correlated (correlation = 0.80). Because arsenobetaine is a part of total arsenic, it should first be subtracted from total arsenic rather than being added to the statistical model. Doing so yields an OR of 1.15 (0.53-2.50). CONCLUSION: These findings show no evidence of increased risk of diabetes with arsenic exposure in this dataset. This underscores the importance of valid statistical techniques and careful consideration of scientific plausibility when investigating low-concentration chemical exposures.",
Arsenic,2337117,"Iodine mobilization in groundwater system at Datong basin, China: Evidence from hydrochemistry and fluorescence characteristics Abstract: Characterizing the speciation of iodine in groundwater is essential for understanding its hydrogeochemical behavior in aquifer systems. To quantify the variations in iodine speciation and assess factors controlling the distribution and transformation of iodine, 82 groundwater samples and 1 rain water were collected from the Datong basin, northern China in this study. Factor analysis (FA) and excitation emission matrix with parallel factor analysis (EEM-PARAFAC) were used to clarify the potential relationships among iodine species and other hydrochemical parameters. The iodine concentrations of groundwater range from 623 to 1380 mu g L-1 with 47% of samples exceeding its drinking water level of 150 mu g L-1 as recommended by the Chinese government 57% of samples have ratios of iodate to total iodine greater than 60%, while iodide as the major species in 22% of the samples. Significant amounts of organic iodine with concentrations higher than 100 mu g L-1 were observed in 9 groundwater samples. Redox conditions of groundwater system strongly affect iodine concentration and speciation of inorganic iodine in groundwater, and extremely reducing condition restricts the iodine release from sediments into groundwater. The results of FA show that iodine mobilization in groundwater is related to the nature of dissolved organic matter. EEM-PARAFAC model demonstrates the dominance of terrestrial DOM sources and the presence of microbial activities in groundwater system of the Datong basin. It is proposed that degradation of organic matter and reductive dissolution of iron oxyhydroxides are major hydrogeochemical processes responsible for the mobilization of iodine release and the genesis of organic iodine.",
Arsenic,1508564,"Imogolite-like nanotubes: structure, stability, electronic and mechanical properties of the phosphorous and arsenic derivatives Abstract: Imogolite is a single-walled aluminosilicate nanotube (NT) found in nature that can be easily synthesized, as well as its analogue aluminogermanate NT. Based on geometrical assumptions and pKa values, species such as HPO, HPO, HAsO, HAsO could also be candidates to form imogolite-like structures. In the present work, we provide insights about the stability, electronic, structural and mechanical properties of possible imogolite like NTs by means of self-consistent charge density-functional tight-binding method (SCC-DFTB). Similarly to aluminogermanate, where the tetrahedral silicate groups are replaced by germanate, in this work tetrahedral silicate groups are substituted by phosphate, phosphite, arsenate and arsenite units in the imogolite structure. Detailed analysis is focused on structural properties, strain energy, band gap and Mulliken charges distribution. The calculated strain energy curves for all studied zigzag imogolite-like NTs present well-defined minima, which change as a consequence of composition variation. Moreover, the strain energy curves of armchair imogolite-like NTs also present minima, although in all cases less stable than zigzags by at least 2.2 meV per atom. The insulating NT behaviour changes after internal modification from silicate to phosphate, phosphite, arsenate and arsenite, as well as the charge distribution inside and outside the nanotubes.",
Arsenic,627319,"Coordination of altered DNA repair and damage pathways in arsenite-exposed keratinocytes Abstract: Human exposure to arsenic, a ubiquitous and toxic environmental pollutant, is associated with an increased incidence of skin cancer. However, the mechanism(s) associated with AsIII-mediated toxicity and carcinogenesis at low levels of exposure remains elusive. Aberrations in cell proliferation, oxidative damage, and DNA-repair fidelity have been implicated in sodium arsenite (AsIII)-mediated carcinogenicity and toxicity, but these events have been examined in isolation in the majority of biological models of arsenic exposure. We hypothesized that the simultaneous interaction of these effects may be important in arsenic-mediated neoplasia in the skin. To evaluate this, normal human epidermal keratinocytes (NHEK) were exposed to nontoxic doses (0.005-5 micro M) of AsIII and monitored for several physiological endpoints at the times when cells were harvested for gene expression measurements (1-24 h). Two-fluor cDNA microarray analyses indicated that AsIII treatment decreased the expression of genes associated with DNA repair (e.g., p53 and Damage-specific DNA-binding protein 2) and increased the expression of genes indicative of the cellular response to oxidative stress (e.g., Superoxide dismutase 1, NAD(P)H quinone oxidoreductase, and Serine/threonine kinase 25). AsIII also modulated the expression of certain transcripts associated with increased cell proliferation (e.g., Cyclin G1, Protein kinase C delta), oncogenes, and genes associated with cellular transformation (e.g., Gro-1 and V-yes). These observations correlated with measurements of cell proliferation and mitotic measurements as AsIII treatment resulted in a dose-dependent increase in cellular mitoses at 24 h and an increase in cell proliferation at 48 h of exposure. Data in this manuscript demonstrates that AsIII exposure simultaneously modulates DNA repair, cell proliferation, and redox-related gene expression in nontransformed, normal NHEK. It is anticipated that data in this report will serve as a foundation for furthering our knowledge of AsIII-regulated gene expression in skin and other tissues and contribute to a better understanding of arsenic toxicity and carcinogenesis.",
Arsenic,627296,"Formamidopyrimidine-DNA glycosylase enhances arsenic-Induced DNA strand breaks in PHA-stimulated and unstimulated human lymphocytes Abstract: To confirm that arsenic (As) induces oxidative DNA damage in phytohemagglutinin (PHA)-stimulated and unstimulated human lymphocytes, we used the alkaline comet assay combined with specific enzyme [formamidopyrimidine-DNA glycosylase (FPG)] digestion to measure As-induced base damage. The results showed that the enzyme-sensitive sites were readily detected with the alkaline comet assay after the cells were treated with 10 microM As for 2 hr. The repair patterns observed for FPG-created DNA single strand breaks (SSBs) in As-treated cells were comparable to those in hydrogen peroxide (H(2)O(2))-treated cells. The enzyme-created SSBs, As-induced base damage, were more significant in PHA-stimulated lymphocytes. About 63% and 68% of SSBs induced by As and H(2)O(2), respectively, were repaired in PHA-stimulated lymphocytes by 2-hr repair incubation, but about 34% and 43%, respectively, were repaired in unstimulated cells. About 40% and 49% of base damage induced by As and H(2)O(2), respectively, were repaired in PHA-stimulated lymphocytes, but about 19% and 21%, respectively, were repaired in unstimulated cells. These results indicated that As induced oxidative DNA damage in human lymphocytes at micromolar concentrations. The damaged bases could be chiefly purines or formamidopyrimidines. Like the damage induced by H(2)O(2), As-induced DNA damage was repaired more slowly in unstimulated lymphocytes.",
Arsenic,698900,"Cause-specific mortality among male chemical workers Abstract: Cause specific mortality was surveyed among 37,682 male employees with three or more days of service between 1940 and 1982 at the Midland or Bay City, Michigan, locations of Dow Chemical USA. Vital status was ascertained through 1982 for 97.5% of the cohort members, and death certificates were obtained for 97.1% of the 7,751 decedents. Comparisons of observed mortality with expected levels based on any of three general population groups (US, Michigan, or seven local counties) consistently demonstrated lower mortality in the cohort from each of the major causes of death, including total malignant neoplasms. Unique among hourly employees was significant excess mortality in the categories of cancer of other lymphatic tissue, and motor vehicle accidents, and both hourly and salaried nonexempt employees experienced significantly higher mortality from other and ill-defined cancers. The influence of duration of employment and age at and period of hire were explored with the Mantel-Haenszel method as adapted for a cohort study. Results were evaluated both including and excluding the mortality experience of subsets of employees with past exposure to known human carcinogens (arsenic, asbestos, bis-chloromethyl ether, benzene, organic dyes, and vinyl chloride). The use of the general mortality survey in monitoring whether or not there are major health problems among the employees and in setting research priorities is emphasized.",
Arsenic,1352690,"HSP56 - A NOVEL HEAT-SHOCK PROTEIN ASSOCIATED WITH UNTRANSFORMED STEROID-RECEPTOR COMPLEXES Abstract: The recently-described p59 protein has been shown to be associated with untransformed steroid receptors present in rabbit uterus and rat liver cytosols (Tai, P. K., Maeda, Y., Nakao, K., Wakim, N. G., Duhring, J. L., and Faber, L. E. (1986) Biochemistry 25, 5269-5275; Renoir, J.-M., Radanyi, C., Faber, L. E., and Baulieu, E.-E. (1990) J. Biol. Chem. 265, 10740-10745), while a smaller version of this protein (p56) interacts with glucocorticoid receptors in human IM-9 cell cytosols (Sanchez, E. R., Faber, L. E., Henzel, W. J., and Pratt, W. B. (1990) Biochemistry 29, 5145-5152). In addition to interacting with glucocorticoid receptors, the p56 protein of IM-9 cell cytosol is also found as part of a large heteromeric complex that contains both the 70-kDa and 90-kDa heat shock proteins (hsp70 and hsp90, respectively). Given this association of p56 with the two major stress proteins, I have speculated that p56 may itself be a heat shock protein. In this paper, the effect of heat stress on the rate of synthesis of p56 is determined. Intact IM-9 cells were exposed to 37 or 43 degrees C for 4 h, followed by pulse-labeling with [35S]methionine. Analysis of whole cytosolic extracts by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography reveal an increased rate of radiolabeling for hsp70, hsp90, hsp100, ad hsp110, but no heat-inducible protein of smaller relative molecular mass is detected. However, immune-purification of p56 from normal and heat-stressed cytosols with the EC1 monoclonal antibody results in the presence of a 56-kDa protein that exhibits an increased rate of synthesis in response to heat stress. The results of two-dimensional gel Western blots employing the EC1 antibody demonstrate that this heat-inducible protein is indeed the EC1-reactive p56 protein and that the induction effect is not due to unequal yields of p56 during immune-purification. Heat stress has no effect on the composition of the p56.hsp.70.hsp90 complex, except that the complex derived from heat shocked-cells contains both the constitutive and heat-inducible forms of hsp70. Induction of p56 also occurs in IM-9 cells subjected to chemical stress (sodium arsenite). It is proposed that p56 is a steroid receptor-associated heat shock protein which can now be termed hsp56. Like hsp90, hsp56 likely serves in some vital cellular role apart from any specific function it provides in steroid receptor action.",
Arsenic,2278607,"Does radial oxygen loss and iron plaque formation on roots alter Cd and Pb uptake and distribution in rice plant tissues? Abstract: Background and Aims: Metal (e.g. Cd and Pb) pollution in agricultural soils and crops have aroused considerable attention in recent years. This study aimed to evaluate the effects of ROL and Fe plaque on Cd and Pb accumulation and distribution in the rice plant. Methods: A rhizobag experiment was employed to investigate the correlations among radial oxygen loss (ROL), Fe plaque formation and uptake and distribution of Cd and Pb in 25 rice cultivars. Results: Large differences between the cultivars were found in rates of ROL (1.55 to 6.88 mmol O-2 kg(-1) root d.w. h(-1)), Fe plaque formation (Fe: 6,117-48,167 mg kg(-1); Mn: 127-1,089 mg kg(-1)), heavy metals in shoot (Cd: 0.13-0.35 mg kg(-1); Pb: 4.8-8.1 mg kg(-1)) and root tissues (Cd: 1.1-3.5 mg kg(-1); Pb: 45-199 mg kg(-1)), and in Fe plaque (Cd: 0.54-2.6 mg kg(-1); Pb: 102-708 mg kg(-1)). Rates of ROL were positively correlated with Fe plaque formation and metal deposition on root surfaces, but negatively correlated with metal transfer factors of root/plaque and distributions in shoot and root tissues. Conclusions: ROL-induced Fe plaque promotes metal deposition on to root surfaces, leading to a limitation of Cd and Pb transfer and distribution in rice plant tissues.",
Arsenic,734978,"Genome-wide analysis of DNA methylation and gene expression changes in the mouse lung following subchronic arsenate exposure Abstract: Alterations in DNA methylation have been proposed as a mechanism for the complex toxicological effects of arsenic. In this study, whole-genome DNA methylation and gene expression changes were evaluated in lungs from female mice exposed for 90 days to 50 ppm arsenate (As) in drinking water. DNA methylation changes were measured using reduced representation bisulfite deep sequencing. Differential methylation was observed in approximately 700 and 1900 start and transcribed regions, respectively. The start regions showed bias toward decreased methylation. No bias was observed in the transcribed region. A comparison of absolute methylation levels in the control animals with treatment-related changes in methylation showed that baseline methylation levels play a role in determining which genes are methylated. Genes with low absolute methylation levels in the start region showed a trend toward increased As-related methylation and decreased expression. Genes with high levels of methylation in the transcribed region showed a trend toward decreased As-related methylation, but no change in expression. No overall correlation between treatment-related changes in methylation and expression was identified. Among genes showing differential methylation in the start region and differential expression, only 57% showed an inverse correlation. The results suggest that differential methylation following As treatment may only play a permissive role in regulating expression. Despite the low correlation, the subset of 17 genes that showed an inverse relationship between As-related methylation and expression included a substantial number that has been demonstrated to play a functional role in cancer-related processes and other effects consistent with arsenic exposure.",
Arsenic,2343464,"Metals in cosmetics: An a posteriori safety evaluation Abstract: According to EU Regulation No. 1223/2009/CE cosmetic products for daily use can contain 'technically unavoidable traces' of metals. This definition is too vague. Authorities should set well-defined limits, considering the risks associated with metal contamination of personal care products (PCPs). This paper characterizes the risk arising from a number of metals (antimony, arsenic, cadmium, cobalt, chromium, mercury, nickel, lead) that may occur in 'unavoidable traces&quot; in raw materials and, consequently, in PCPs. A 'worst case scenario' was adopted, based on the following assumptions: (i) the individual ingredients contained the maximum amount in traces allowed for each metal; (ii) the hypothetical PCP was produced exclusively with that single ingredient; (iii) when absorption through the skin was not known, data related to oral absorption were used. Risk characterization was performed calculating the Systemic Exposure Dosage (SED) and the Margin of Safety (MoS=NOAEL or BMDL10/SED). Exposure to the allegedly 'technically unavoidable' maximum amounts of metals in cosmetic ingredients resulted in MoSs exceeding 100 (safety threshold) with one exception. This suggests that the availability of experimental dermal absorption rates could enable significant improvement in MoS, thus increasing safety levels. Although results are reassuring, the authors recommend minimization of contamination, according to the state of the art of manufacturing methods.",
Arsenic,1342698,"Comparison of trace elements in bottled and desalinated household drinking water in Kuwait Abstract: The levels of the trace elements aluminum (Al), arsenic (As), boron (B), barium (Ba), beryllium (Be), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), molybdenum (Mo), nickel (Ni), antimony (Sb), selenium (Se), strontium (Sr), titanium (Ti), vanadium (V), and zinc (Zn) were determined in 93 brands of non-carbonated (BW) and carbonated (CBW) bottled water available in Kuwaiti markets and in 321 samples of desalinated household water (HW) collected from 99 sampling locations, which covered 95% of Kuwait's residential areas. The study yielded a large range of results for most of these elements, and the difference between the lowest and highest measured values exceeded three orders of magnitude for some elements in a number of the BW and CBW brands. With a few exceptions, the results for the HW and BW were found to comply with the United States-Environmental Protection Agency and World Health Organization guideline values. The elements Fe, Pb, Hg, and Ni exceeded these GVs in 8.5, 0.3, 1.2, and 1% of the HW samples, respectively. One brand of BW exceeded the GV for B, while the levels of B, Ba, Be, Fe, and Mn exceeded the GVs in 35, 15, 5, 75, and 25% of the CBW brands, respectively. Correlations were found between the levels of some elements and either the desalination plant that produced the HW or the country of origin of the BW or CBW. The levels of the elements Al, Cu, Fe, and Zn in HW were higher in the summer than in the winter, with 14, 14, 42, and 18% increases, respectively. Nutritional evaluation revealed that significant percentages of the DRIs of Cr, Cu, Fe, and Se can be provided by drinking 2?L of HW, and significant percentages of the DRIs of B, Cr, Cu, and Mo can be provided by drinking 2?L of BW.",
Arsenic,1022098,"Protective effect of curcumin against arsenic-induced apoptosis in murine splenocytes in vitro Abstract: Arsenic is a potent environmental pollutant and immunotoxic agent. Curcumin is a natural anti-oxidant used to treat a broad variety of diseases. Here, the effects were investigated of curcumin on sodium arsenite-induced apoptosis in murine splenocytes in vitro. Cells were exposed to sodium arsenite (NaAsO(2), 5 µM) with and without curcumin (5 and 10 µg/ml) and incubated at 37°C for 12?h. NaAsO(2) caused a decrease in cell viability and induction of apoptosis. These outcomes were concurrent with increases in the numbers of cells with reactive oxygen species generation, loss of mitochondrial transmembrane potential, an increase in the frequency of cells with sub-G(1) DNA content, and DNA fragmentation. Co-administration of curcumin with the NaAsO(2) caused significant recoveries in cell viability values and mitigation of the induced apoptosis-related molecular changes. A significant protection against apoptosis parameters in murine splenocytes simultaneously treated with NaAsO(2) and curcumin suggested a protective efficacy of curcumin. From the results it is concluded that the immuno-modulation exerted by curcumin might be attributed to its multifaceted effects including its anti-oxidative and anti-apoptotic properties. These findings have implications not only for the under-standing of the toxicity of arsenic to murine splenocytes in vitro but are also potentially important for developing preventive and/or corrective strategies against/during chronic arsenicosis.",
Arsenic,1347486,Immediate chelation with DMSA for acute arsenic overdose prevents chronic toxicity from arsenic poisoning Abstract: ,
Arsenic,2343566,"Microbially Facilitated Incorporation of As(III) into Bioreduced Fe-(hydr)oxide Minerals Abstract: Ferric (oxyhydr)oxide minerals are widespread in the (sub)surface soils such as in agricultural fields, and arsenic compounds have been used widely in the production of pesticides, herbicides, and insecticides, which have caused potential As contaminations in the (sub)surface soils including Fe-(oxyhydr)oxides. Because one of the potential relationships between Fe-(oxyhydr)oxides and As was suggested above, scientists have been motivated to investigate the relationship between Fe(oxyhydr)oxides and As. In the present study, a dissimilatory Fe(III)-reducing bacterium, Shewanella sp. HN-41 was employed to elucidate effect of microbial Fe(a) reduction on the relationship between Fe-(oxyhydr)oxides and As, and incubated with lactate and synthetic Fe(III)-oxyhydroxide as the electron donor and acceptor, respectively, in the presence of As(III). For comparison, abiotic incubations were performed under the same condition except for addition of the bacterial cells. By sequential chemical extraction of the incubation products, As(III) was determined to be incorporated into the bioreduced minerals at higher concentrations (similar to 14.4% of the total extracted As) than in the abiotic products (similar to 40.2%) that were aged for the same duration as the microbial incubation. The results of this study emphasized that bacterial Fe(III)-reduction of the initial synthetic Fe-oxyhydroxide, akaganeite, induced more As(II) incorporation into the structures of the final product minerals than the abiotic transformation of the initial As(II)-adsorbed Fe-oxyhydroxide in the control incubations. Thus, microbial Fe(III)-reduction-mediated incorporation of As(IIII) into biotransformed Fe-(oxy)(hydr)oxide minerals could be suggested as one of potential strategies for arsenic immobilization in anoxic soils and groundwater.",
Arsenic,1326987,"Differential roles for Nrf2 and AP-1 in upregulation of HO-1 expression by arsenite in murine embryonic fibroblasts Abstract: Heme oxygenase-1 (HO-1) is markedly upregulated by sodium arsenite and previous studies implicated the transcriptional enhancers Nrf2 and AP-1 in arsenite-induced ho-1 gene expression in murine cells. To further evaluate the role of Nrf2 and its signalling pathway in the induction of HO-1 in response to low levels of arsenite, this paper studied wild-type and Nrf2-deficient murine embryonic fibroblasts. It was found that Nrf2 plays a crucial role in the early activation of ho-1 transcription and that increased Nrf2 levels returned to basal levels within 24 h. In Nrf2(-/-) cells, HO-1 gene activation increased gradually and HO-1 protein levels were approximately half of those attained in Nrf2(+/+) cells. The tyrosine kinase inhibitor genistein and JNK inhibitor SP600125 significantly attenuated arsenite induced increases in ho-1 mRNA levels in Nrf2 deficient cells but had negligible effects on Nrf2 activation, suggesting tyrosine kinase/JNK/c-Jun plays a key role in the HO-1 upregulation via AP-1.",
Arsenic,1248978,"Association of arsenic levels in soil and water with urinary arsenic concentration of residents in the vicinity of closed metal mines Abstract: Arsenic (As) pollution in the surroundings of metal mines has been observed, and may induce serious health problems, in particular cancer. Health hazard attributed to As in contaminated soil and water in the vicinity of closed or abandoned metal mines may be high. Little is known about how environmental exposure to As has affected the health of resident near closed metal mines. The objectives of this study were to compare the urinary level of As for those living near closed metal mines (the exposed group) with that of non-exposed group; and to investigate the correlation between As levels in soil (Soil(As)) and water (Water(As)) and the urinary levels (Urine(As)) of residents in the exposed group. Data for Soil(As) and Water(As) were obtained from the national environmental survey performed between 2003 and 2005 by the Ministry of Environment in Korea. To measure Urine(As), 2674 and 237 subjects were selected from 67 closed metal mines (exposed areas) and two rural areas (non-exposed areas), respectively. Five milliliters of urine samples were taken, and graphite furnace atomic absorption spectrometry was used to analyze Urine(As). Of all the exposed areas, high Soil(As) and Water(As) areas that exceed the Korean standards of As in soil (6mg/kg-soil) and stream or groundwater (0.05mg/l-water) were classified to evaluate the health risks in high polluted areas. Also, high Urine(As) group was defined as 20?g/g creatinine or more. Student's t-test was performed to compare the Urine(As) level between the exposed and non-exposed groups. The odds ratio (OR) was calculated by a logistic analysis to evaluate the risk for high Urine(As) level from high Soil(As) and Water(As) areas. The mean of urinary As were 8.90±8.34?g/g-creatinine for the exposed group and 7.68±4.98?g/g creatinine for the non-exposed group, respectively; and the significant difference of urinary As level was observed between both groups (p&lt;0.05). Moreover, the means for urinary As of people in areas with high As level in soil and water were significantly higher than that for the control areas (p&lt;0.001), and these differences were more pronounced for the As level in water. The odds of subjects with high Urine(As) were positively and significantly associated with living in the areas with high As level in soil (OR=1.62; 95% C.I.=1.13-2.31). These associations were much stronger for the areas with high Water(As) (OR=3.79; 95% C.I.=2.32-6.19). These results indicate that the high level of As in environment may increase the risk of having high urinary As level of people in the exposed areas.",
Arsenic,1021533,"Interleukin-8 (IL-8) over-production and autocrine cell activation are key factors in monomethylarsonous acid [MMA(III)]-induced malignant transformation of urothelial cells Abstract: The association between chronic human exposure to arsenicals and bladder cancer development is well recognized; however, the underlying molecular mechanisms have not been fully determined. We propose that inflammatory responses can play a pathogenic role in arsenic-related bladder carcinogenesis. In previous studies, it was demonstrated that chronic exposure to 50 nM monomethylarsenous acid [MMA(III)] leads to malignant transformation of an immortalized model of urothelial cells (UROtsa), with only 3 mo of exposure necessary to trigger the transformation-related changes. In the three-month window of exposure, the cells over-expressed pro-inflammatory cytokines (IL-1?, IL-6 and IL-8), consistent with the sustained activation of NFK? and AP1/c-jun, ERK2, and STAT3. IL-8 was over-expressed within hours after exposure to MMA(III), and sustained over-expression was observed during chronic exposure. In this study, we profiled IL-8 expression in UROtsa cells exposed to 50 nM MMA(III) for 1 to 5 mo. IL-8 expression was increased mainly in cells after 3 mo MMA(III) exposure, and its production was also found increased in tumors derived from these cells after heterotransplantation in SCID mice. UROtsa cells do express both receptors, CXCR1 and CXCR2, suggesting that autocrine cell activation could be important in cell transformation. Supporting this observation and consistent with IL-8 over-expression, CXCR1 internalization was significantly increased after three months of exposure to MMA(III). The expression of MMP-9, cyclin D1, bcl-2, and VGEF was significantly increased in cells exposed to MMA(III) for 3 mo, but these mitogen-activated kinases were significantly decreased after IL-8 gene silencing, together with a decrease in cell proliferation rate and in anchorage-independent colony formation. These results suggest a relevant role of IL-8 in MMA(III)-induced UROtsa cell transformation.",1
Arsenic,1337286,"Association between hypertension and chronic arsenic exposure in drinking water: A cross-sectional study in Bangladesh Abstract: Chronic arsenic exposure and its association with hypertension in adults are inconclusive and this cross-sectional study investigated the association. The study was conducted between January and July 2009 among 1,004 participants from 1,682 eligible women and men aged ?30 years living in rural Bangladesh who had continuously consumed arsenic-contaminated drinking water for at least 6 months. Hypertension was defined as systolic blood pressure ?140 mmHg (systolic hypertension) and diastolic blood pressure ?90 mmHg (diastolic hypertension). Pulse pressure was calculated by deducting diastolic from systolic pressure and considered to be increased when the difference was ?55 mmHg. The prevalence of hypertension was 6.6% (95% CI: 5.1-8.3%). After adjustment for other factors, no excess risk of hypertension was observed for arsenic exposure >50?g/L or to that of arsenic exposure as quartiles or as duration. Arsenic concentration as quartiles and >50 ?g/L did show a strong relationship with increased pulse pressure (adjusted OR: 3.54, 95% CI: 1.46-8.57), as did arsenic exposure for ?10 years (adjusted OR: 5.25, 95% CI: 1.41-19.51). Arsenic as quartiles showed a dose response relationship with increased pulse pressure. Our study suggests an association between higher drinking water arsenic or duration and pulse pressure, but not hypertension.",
Arsenic,1579289,"Assessment of biochar and iron filing amendments for the remediation of a metal, arsenic and phenanthrene co-contaminated spoil Abstract: Sites contaminated with mixtures of metals, metalloids and organics are difficult to remediate as each contaminant type may require a different treatment. Biochar, with high metal sorption capacity, used singly and in combination with iron filings, is investigated in microcosm trials to immobilise metal(loid)s within a contaminated spoil, thereby enabling revegetation and degradation of organic pollutants. A mine spoil, contaminated with heavy metals, arsenic and spiked with phenanthrene was treated with either 1%w/w biochar, 5%w/w iron or their combination, enhancing phenanthrene degradation by 44-65%. Biochar treatment reduced Cu leaching and enabled sunflower growth, but had no significant effect on As mobility. Iron treatment reduced Cu and As leaching but negatively impacted soil structure and released high levels of Fe causing sunflower plant mortality. The combined treatment reduced both Cu and As leaching and enabled sunflower growth suggesting this could be a useful approach for treating co-contaminated sites.",
Arsenic,2088542,"UV/H2O 2 oxidation of arsenic and terbuthylazine in drinking water Abstract: Arsenic is a widespread contaminant in the environment. The intake of water containing high concentrations of arsenic could have serious impact on human health, such as skin and lung cancer. In the European Union, thus, also in Italy, the arsenic limit in drinking water is 10 ?g L(-1). Several water remediation treatment technologies are available for arsenic removal. For some processes, the removal efficiencies can be improved after an oxidation step. Most full-scale applications are based on conventional oxidation processes for chemical micropollutant removal. However, if water contains arsenic and refractory organic contaminants, the advanced oxidation processes could be considered. The aim of this work was to investigate the effectiveness of ultraviolet (UV) radiation alone and in combination with hydrogen peroxide for the oxidation of arsenic and terbuthylazine (TBA). The experimental tests were performed in groundwater at the laboratory scale (0.1 mg L(-1) As(III) and 10 ?g L(-1) TBA). Hydrogen peroxide alone (15 mg L(-1)) was ineffective on both arsenic and TBA oxidation; the 253.7-nm radiation alone did not oxidize arsenic(III), but photolyzed efficiently TBA (52 % removal yield at a UV dose of 1,200 mJ cm(-2)). The UV/H2O2 advanced oxidation (UV dose 600-2,000 mJ cm(-2), 5-15 mg L(-1) H2O2) was the most effective process for the oxidation of both arsenic and TBA, with observed oxidation efficiencies of 85 and 94 %, respectively, with 5 mg L(-1) H2O2 and a UV dose of 2,000 mJ cm(-2).",
Arsenic,1173152,"Sequential phosphorylation by protein kinase CK2 regulates NRF2 activation and degradation: Potential role in arsenicinduced skin carcinogenesis Abstract: Arsenic is a well-documented human carcinogen that targets skin and may induce genetic damage through generation of reactive oxygen species (ROS). Nrf2 is a key transcription factor that regulates expression of genes whose products protect cells against ROS. We have explored here the role that phosphorylation plays in regulating Nrf2 activity and have explored the association between protein kinase CK2, Nrf2 activation and arsenic-induced skin carcinogenesis. Events relative to skin carcinogenesis were studied in a human keratinocyte cell line (HaCaT) undergoing malignant transformation as a result of chronic arsenic exposure. Nrf2 phosphorylation was detected in acute arsenic-treated cells using Nrf2 western blot both before and after in vitro phosphatases treatment. Gel-shift assay, Real-time RT-PCR and Western blot were employed to evaluate Nrf2 transcriptional activity in both its native and phosphorylated forms. Two phosphorylated forms of Nrf2 were identified after arsenic-induced oxidative stress. Additional study showed CK2 mediated, sequential phosphorylation of Nrf2 to first produce an active, phosphorylated form and then a hyper-phosphorylated form which was inactive and underwent degradation. Continuous exposure to arsenic (100 nM) for 28 weeks induced malignant transformation in HaCaT cells and concurrently upregulated CK2 expression and activity. Arsenic-transformed keratinocytes had more Nrf2 hyper-phosphorylation and exhibited a dysfunctional antioxidant response. These results provide compelling evidence for phosphorylation by CK2 as a critical controlling factor in Nrf2-mediated cellular antioxidant response. Chronic arsenic-induced CK2 upregulation is a potentially important event in skin carcinogenesis as it may increase the susceptibility to oxidative damage by altering Nrf2 phosphorylation and cellular antioxidant response.",
Arsenic,1379231,"Biomonitoring of exposure to lewisite based on adducts to haemoglobin Abstract: The development of a procedure for retrospective detection and quantitation of exposure to the arsenical dichloro(2-chlorovinyl)arsine (lewisite; L1) has been initiated. Upon incubation of human blood with [14C]L1 (20 nM-0.2 mM) in vitro, more than 90% of the total radioactivity was found in the erythrocytes and 25-50% of the radioactivity becomes associated with globin. Evidence was obtained for the presence of several binding sites. One type of binding was identified as L1-induced crosslinking of cysteine residues 93 and 112 of the beta-globin chain. A method was developed for extraction of bound and unbound 2-chlorovinylarsonous acid (CVAA), a major metabolite of L1, from whole blood after treatment with 2,3-dimercapto-1-propanol (BAL). Subsequent to derivatization with heptafluorobutyryl imidazole, the CVAA-BAL derivative could be analysed at a 40-fmol level by means of gas chromatography-mass spectroscopy (GC-MS) under electron impact conditions. With this procedure, in vitro exposure of human blood to 1 nM L1 could be determined. The same procedure was applied to the analysis of human urine samples spiked with CVAA. In vivo exposure of guinea pigs could be established at least 240 h after subcutaneous administration of the agent (0.25 mg/kg) by the determination of bound and unbound CVAA in the blood. In the urine of these animals, CVAA could be detected for 12 h after exposure.",
Arsenic,2343505,"A statistical approach for arsenic adsorption onto turkey clinoptilolite Abstract: The present study investigated the optimization of arsenic adsorption onto natural clinoptilolite (NC-Na). Response surface methodology in combination with Box-Behnken design was used to optimize the parameters of the adsorption process. Solution pH, temperature, and initial arsenic concentration were chosen as the main process variables, and the amount of arsenic adsorbed was selected as the investigated response. The analysis of variance results of the response surface model for arsenate (As(V)) adsorption on NC-Na showed that the effects and the interactions of pH and temperature were highly significant according to the p values (p?&lt;?0.05). The optimum conditions were found to be the solution pH of 5.0, temperature of 45 °C, and initial concentration of 7.8 mg L(-1). The response surfaces derived from the models revealed that solution pH and temperature showed the greatest effect on the As(V) adsorption capacity of natural clinoptilolite.",
Arsenic,656941,"Cell-transforming activity of fourteen chemical agents used in dental practice in Syrian hamster embryo cells Abstract: Fourteen chemical agents used in dental practice were assessed for their cell-transforming activity using the Syrian hamster embryo (SHE) cell transformation assay system. The cell-transforming activity was quantitatively assessed by the frequency of morphological transformation (MT) in SHE cells induced by these agents. MT was induced by m-cresol, guaiacol, formaldehyde, sodium hypochlorite, hydrogen peroxide, sodium arsenite, acid fuchsin, and basic fuchsin, but not by p-chlorophenol, p-phenolsulfonic acid, glutaraldehyde, and erythrosine B. Iodine and chlorhexidine exhibited positive and pseudopositive responses, respectively. The chemical agents exhibiting a negative or pseudopositive response neither induced nor enhanced MT even in the presence of exogenous metabolic activation.",
Arsenic,1794756,"Basal cell carcinoma: A paradigm for targeted therapies Abstract: Introduction: Basal cell carcinoma (BCC) is the most frequent cancer with increasing incidence over the last decades. Standard of care is surgical excision, upon which complete tumour clearance is achieved in most cases. However, a small subgroup of patients will have remnants of disease post-excision and require further treatment options. Over 90% of all BCCs carry a mutation in PTCH 1 or SMO, two conducting proteins of the Hedgehog pathway (Hh). Therefore, inhibition of the Hh pathway is a promising option for systemic first-line therapy. Vismodegib was the first developed of these small molecules, which was approved by the FDA in January 2012. Areas covered: The authors review current treatment modalities for BCC and discuss current developments in pharmacological therapy. The current literature including meta-analyses, the Cochrane database and registered as well as completed randomized controlled trials. Expert opinion: Hh inhibitors are a new promising treatment option for patients with advanced or metastatic BCC. Phase I and II clinical trials with the Hh inhibitor, vismodegib, showed a significant reduction in tumour size and appearance of new tumours with relatively good tolerability. Nevertheless, further investigation on new molecules and the effectiveness of an intermittent dosing regimen is necessary.",
Arsenic,1034056,"Heat shock proteins are methylated in avian and mammalian cells Abstract: Exposure of chicken cells grown in tissue culture to heat shock or sodium arsenite results in a dramatic increase in the synthesis of three major polypeptides with molecular weights of 83,000 (HSP 83), 68,000 (HSP 68; referred to here as &quot;thermin&quot;), and 25,000 (HSP 25). Incubation of BHK-21 or HeLa cells under the same conditions results in induction of HSP 68 and a 66,000-dalton polypeptide (HSP 66). Chicken thermin is resolved by isoelectric focusing into a major acidic and a more-basic component; mammalian thermin is resolved only into one major acidic component. HSP 83 and the acidic form of thermin are highly conserved in all avian and mammalian cells examined as judged by their electrophoretic mobilities, isoelectric points, and one-dimensional peptide maps. In addition, the acidic form of thermin is indistinguishable from a protein that copurifies with brain microtubules and that remains associated with the intermediate filament-enriched Triton/KCl cytoskeletons of cells grown in tissue culture. Thermin is also a component of skeletal myofibrils. HSP 83 and thermin are methylated in cells cultured under normal growth conditions. Induction of heat shock proteins by incubation of cells in the presence of sodium arsenite results in a marked methylation of the newly synthesized thermin. Under the same experimental conditions, no significant increase in methylation of the HSP 83 is observed. HSP 25 is not methylated in untreated cells or in cells treated with sodium arsenite. These results suggest that methylation of heat shock proteins may have an important role in regulating their function.",
Arsenic,1508688,"Arsenic removal from natural groundwater using cupric oxide Abstract: Groundwater is a main source of drinking water for some rural areas. People in these rural areas are potentially at risk from elevated levels of arsenic (As) due to a lack of water treatment facilities. The objectives of this study were to (1) measure As concentrations in approximately 50 groundwater samples from rural domestic wells in the western United States, (2) explore the potential of cupric oxide (CuO) particles in removal of As from groundwater samples under natural conditions (i.e., without adding competing anions and adjusting the pH or oxidation state), and (3) determine the effects of As removal on the chemistry of groundwater samples. Forty-six groundwater well samples from rural domestic areas were tested in this study. More than 50% of these samples exceeded the U.S. Environmental Protection Agency Maximum Contaminant Limit (US EPA MCL) of 10 µg/L for As. CuO particles effectively removed As from groundwater samples across a wide range of pH (7.11 and 8.95) and concentrations of competing anions including phosphate (&lt;0.05 to 3.06 mg/L), silica (&lt;1 to 54.5 mg/L), and sulfate (1.3 to 735 mg/L). Removal of As showed minor effects on the chemistry of groundwater samples, therefore most of the water quality parameters remained within the US EPA MCLs. Overall, results of this study could help develop a simple one-step process to remove As from groundwater.",
Arsenic,628324,"Arsenic exposure and prevalence of type 2 diabetes in US adults Abstract: CONTEXT: High chronic exposure to inorganic arsenic in drinking water has been related to diabetes development, but the effect of exposure to low to moderate levels of inorganic arsenic on diabetes risk is unknown. In contrast, arsenobetaine, an organic arsenic compound derived from seafood intake, is considered nontoxic. OBJECTIVE: To investigate the association of arsenic exposure, as measured in urine, with the prevalence of type 2 diabetes in a representative sample of US adults. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study in 788 adults aged 20 years or older who participated in the 2003-2004 National Health and Nutrition Examination Survey (NHANES) and had urine arsenic determinations. MAIN OUTCOME MEASURE: Prevalence of type 2 diabetes across intake of arsenic. RESULTS: The median urine levels of total arsenic, dimethylarsinate, and arsenobetaine were 7.1, 3.0, and 0.9 mug/L, respectively. The prevalence of type 2 diabetes was 7.7%. After adjustment for diabetes risk factors and markers of seafood intake, participants with type 2 diabetes had a 26% higher level of total arsenic (95% confidence interval [CI], 2.0%-56.0%) and a nonsignificant 10% higher level of dimethylarsinate (95% CI, -8.0% to 33.0%) than participants without type 2 diabetes, and levels of arsenobetaine were similar to those of participants without type 2 diabetes. After similar adjustment, the odds ratios for type 2 diabetes comparing participants at the 80th vs the 20th percentiles were 3.58 for the level of total arsenic (95% CI, 1.18-10.83), 1.57 for dimethylarsinate (95% CI, 0.89-2.76), and 0.69 for arsenobetaine (95% CI, 0.33-1.48). CONCLUSIONS: After adjustment for biomarkers of seafood intake, total urine arsenic was associated with increased prevalence of type 2 diabetes. This finding supports the hypothesis that low levels of exposure to inorganic arsenic in drinking water, a widespread exposure worldwide, may play a role in diabetes prevalence. Prospective studies in populations exposed to a range of inorganic arsenic levels are needed to establish whether this association is causal.",
Arsenic,1597299,"Arsenic Release from Soil by a Novel Dissimilatory Arsenate-Reducing Bacterium Anaeromyxobacter sp. PSR-1 Abstract: A novel arsenate-reducing bacterium, designated strain PSR-1, was isolated from arsenic-contaminated soil. Strain PSR-1 was phylogenetically closely related with Anaeromyxobacter dehalogenans 2CP-1(T) with 16S rRNA gene similarity of 99.7%, and coupled the oxidation of acetate with the reduction of arsenate. Arsenate reduction was inhibited almost completely by respiratory inhibitors such as dicumarol and 2-heptyl-4-hydroxyquinoline N-oxide. Strain PSR-1 also utilized soluble Fe(III), ferrihydrite, nitrate, oxygen and fumarate as electron acceptors. Strain PSR-1 catalyzed the release of arsenic from arsenate-adsorbed ferrihydrite. In addition, inoculation of washed cells of strain PSR-1 into sterilized soil successfully reproduced arsenic release. Arsenic K-edge X-ray absorption near-edge structure (XANES) analysis revealed that the proportion of arsenite in the soil solid phase actually increased from 20% to 50% during incubation with washed cells of strain PSR-1. These results suggest that strain PSR-1 is capable of reducing not only dissolved arsenate but also arsenate adsorbed on the soil mineral phase. Arsenate reduction by strain PSR-1 expands the metabolic versatility of Anaeromyxobacter dehalogenans. Considering its distribution throughout diverse soils and anoxic sediments, Anaeromyxobacter dehalogenans may play a role in arsenic release from these environments.",
Arsenic,2088487,"The cold-induced two-component system CBO0366/CBO0365 regulates metabolic pathways with novel roles in cold tolerance of Group I Clostridium botulinum ATCC 3502 Abstract: The two-component system CBO0366/CBO0365 was recently demonstrated to have a role in cold tolerance of Group I Clostridium botulinum ATCC 3502. The mechanisms under its control, ultimately resulting in increased sensitivity to low temperature, are unknown. A transcriptomic analysis with DNA microarrays was performed to identify the differences in global gene expression patterns of the wild-type ATCC 3502 and a derivative mutant with insertionally inactivated cbo0365 at 37 °C and 15 °C. Altogether 150 or 141 chromosomal CDSs were found to be differently expressed in the cbo0365 mutant at 37 °C or 15 °C, respectively, and thus considered to be under direct or indirect transcriptional control of the response regulator CBO0365. Of the differentially-expressed CDSs, expression of 141 CDSs was similarly affected at both temperatures investigated, suggesting that the putative CBO0365 regulon was practically not affected by temperature. The regulon involved genes related to acetone-butanol-ethanol (ABE) fermentation, motility, to arsenic resistance, and phosphate uptake and transport. Deteriorated growth at 17 °C was observed for mutants with disrupted ABE fermentation pathway components (crt, bdh and ctfA), arsenic detoxifying machinery components (arsC and arsR), or phosphate uptake mechanism components (phoT), suggesting roles for these mechanisms in cold tolerance of Group I C. botulinum. Electrophoretic mobility shift assays showed recombinant CBO0365 to bind to the promoter regions of crt, arsR, and phoT, as well as to the promoter region of its own operon, suggesting direct DNA-binding transcriptional activation or repression as means for CBO0365 in regulating these operons. The results provide insight to the mechanisms Group I C. botulinum utilize in coping with cold.",
Arsenic,2343530,"Effects of biochar amendment on root traits and contaminant availability of maize plants in a copper and arsenic impacted soil Abstract: Background and aims Biochar has been proposed as a tool to enhance phytostabilisation of contaminated soils but little data are available to illustrate the direct effect on roots in contaminated soils. This work aimed to investigate specific root traits and to assess the effect of biochar amendment on contaminant availability. Methods Amendment with two different types of biochar, pine woodchip and olive tree pruning, was assessed in a rhizobox experiment with maize planted in a soil contaminated with significant levels of copper and arsenic. Results Amendment was found to significantly improve root traits compared to the control soil, particularly root mass density and root length density. Copper uptake to plants and ammonium sulphate extractable copper was significantly less in the biochar amended soils. Arsenic uptake and extractability varied with type of biochar used but was not considered to be the limiting factor affecting root and shoot development. Conclusions Root establishment in contaminated soils can be enhanced by biochar amendment but choice of biochar is key to maximising soil improvement and controlling contaminant availability.",
Arsenic,1579362,"Effects of ion concentration and natural organic matter on arsenic(V) removal by nanofiltration under different transmembrane pressures Abstract: The removal of As(V) from synthetic water was studied using four different nanofiltration (NF) membranes (ESNA-1-K1, NF270, ESNA-1-LF, and HODRA-CORE). The influences of ion concentration, transmembrane pressure (TMP), and the presence of natural organic matter (humic acid, HA) on the arsenic removal efficiency and permeate flux were investigated. The arsenic rejection of ESNA-1-LF was higher than those of the other membranes in all experiments (&gt; 94%), and the HODRA-CORE membrane gave the lowest removal of arsenic (&lt; 47%). An increase in the ion concentration in the feed solution and addition of HA decreased the arsenic rejection of the HODRA-CORE membrane. However, both increasing of the ion concentration and addition of HA made the rejection increased for the other membranes (ESNA-1-K1, NF270, and ESNA-1-LF). With increasing TMP, for all four NF membranes, increases in both arsenic rejection and permeate flux were observed. The permeate fluxes of the four NF membranes decreased to some extent after addition of HA to the solutions for operating time of 6 hr.",
Arsenic,627452,"Association between arsenic exposure from drinking water and anemia during pregnancy Abstract: OBJECTIVE: Arsenic is associated with numerous health effects. We investigated the association between arsenic exposure from drinking water and anemia during pregnancy. METHODS: We conducted a prospective cohort pregnancy study in two Chilean cities with contrasting drinking water arsenic levels: 40 microg/L versus <1 microg/L. This analysis included 810 women who gave birth to live, singleton infants and had at least one hemoglobin determination during pregnancy. RESULTS: Arsenic exposed women were more likely to be anemic during pregnancy after adjusting for other factors. Furthermore, as pregnancy progressed, the prevalence of anemia rose more sharply among those in the exposed versus unexposed city: 49% versus 17%. CONCLUSION: This study suggests an association between moderate arsenic in drinking water and anemia during pregnancy. Further research is needed to identify the specific types of anemia underlying the association.",
Arsenic,1018326,"Study of muscle glycogen content in both sexes of an Indian teleost Clarias batrachus (Linn.) exposed to different concentrations of arsenic Abstract: The present investigation has been conducted to study the effect of different sublethal concentrations of arsenic (5, 10 and 15 mg/L) on the muscle glycogen content in an Indian teleost, Clarias batrachus, during their post-spawning period (October to January).The species were exposed to various arsenic concentrations for six consecutive days i.e.,144 h. Significant differences in average muscle glycogen content were found in the treated male and female C. batrachus specimens. However, significantly higher (P &lt; 0.01) muscle glycogen content was observed in male fish when compared to females in the untreated specimens. Arsenic caused muscle glycogenolysis in both sexes of C. batrachus. The depletions were not always dose (arsenic concentration) and time dependent, although higher concentrations were more glycogenolytic than the lower concentrations. After 96 h of treatment with arsenic, less depletion of muscle glycogen content was recorded in both sexes of fish.",
Arsenic,46394,"Population-based exposure measurements in EPA region 5: a phase I field study in support of the national human exposure assessment survey Abstract: The National Human Exposure Assessment Survey (NHEXAS) Phase I study is designed to be part of the total NHEXAS framework developed from a series of scientific discussions and workshops conducted by the U.S. Environmental Protection Agency (EPA) during 1992 and 1993. NHEXAS examines total human exposure and is structured to include: Phase I, scoping studies; Phase II, a full national exposure survey; and Phase III, a series of highly focused characterization modules. Our research program examines the scientific issues important to Phase II, including statistical sampling, methods evaluation, media concentration measurements, formulating quality assurance goals, and identification of important pathways leading to exposure. To determine the feasibility of NHEXAS in characterizing human exposure for a representative population, a hypothesis-driven design is used to answer important questions about human exposure to specific environmental contaminants. This paper describes: (1) hypotheses to be tested; (2) contaminants selected for study; (3) strategies for measuring exposure; (4) study area and population; (5) population sampling design; (6) media sampling and analysis procedures; and (7) data analysis. The contaminants of concern in this Phase I study include selected metals and volatile organic compounds. From these classes the first-tier contaminants to be measured are lead, arsenic, benzene, chloroform, perchloroethylene, and trichloroethylene. Contaminants selected for examination may potentially be found in many media (personal-nonoccupational, personal-occupational, indoor, and outdoor residential air; dust; potable water; food/beverages; soil; blood; hair; and urine) and exposures may occur by multiple routes (inhalation, ingestion, dermal). The central hypothesis of our field study is to discover whether individual and population exposures determined by modeled or extant data are/are not significantly different from those determined directly from multipathway and multimedia measurements. In addition, there are a series of subhypotheses ranging from pollutant-specific exposure measurement and body burden hypotheses to the optimization of exposure models. In keeping with the NHEXAS framework, a probability-based population sample for total exposure and the field study will be conducted in counties located throughout EPA Region 5 (Minnesota, Wisconsin, Illinois, Indiana, Ohio, and Michigan). Sampling units will be households and an individual residing within each household. Environmental, exposure, and biological media sample collection will be performed by this consortium. Analyses of the external media and biological media samples will be completed by this consortium or Federal laboratories of the Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), or EPA. The protocols and analytical techniques selected for use represent the best available for total exposure assessment at this time.",
Arsenic,627957,"Effect of arsenic trioxide on cell cycle arrest in head and neck cancer cell line PCI-1 Abstract: Arsenic trioxide (As(2)O(3)) has been shown to inhibit the proliferation of hematologic malignant cells. However, little is known about the effect of As(2)O(3) on solid tumor. In this study, we investigated the antitumoral effect of As(2)O(3) on head and neck cancer cell lines in vitro. Treatment of As(2)O(3) inhibited the proliferation of all of 4 cell lines examined in a dose-dependent manner. To address the mechanism of antitumoral effect of As(2)O(3), cell cycle analysis was attempted in As(2)O(3)-most sensitive PCI-1 cells. Treatment of As(2)O(3) (2 microM) induced efficiently G2/M arrest in PCI-1 cells following 3 days of exposure. During the G2/M arrest, cyclin-dependent kinase inhibitor, p21, was increased in a time-dependent manner. Analysis of cell cycle regulatory proteins demonstrated that As(2)O(3) (2 microM) did not change the steady-state levels of CDK2, CDK4, CDK6, cyclin D1, cyclin E and cyclin A, but decreased the protein levels of cdc2 and cyclin B1. Furthermore, treatment of As(2)O(3) markedly enhanced the binding of p21 with cdc2, and the activity of cdc2 kinase was decreased in a time-dependent manner. These results suggest that As(2)O(3) inhibits the proliferation of head and neck cancer cells via G2/M arrest in association with the induction of p21 and the reduction of cdc2 kinase activity. Copyright 1999 Academic Press.",
Arsenic,1337307,"The need for congressional action to finance arsenic reductions in drinking water Abstract: Many public water systems in the U.S. are unsafe because the communities cannot afford to comply with the current 10 parts per billion (ppb) federal arsenic standard for drinking water. Communities unable to afford improvements remain vulnerable to adverse health effects associated with higher levels of arsenic exposure. Scientific and bipartisan political consensus exists that the arsenic standard should not be less stringent than 10 ppb, and new data suggest additional adverse health effects related to arsenic exposure through drinking water. Congress has failed to reauthorize the Drinking Water State Revolving Fund program to provide reliable funding to promote compliance and reduce the risk of adverse health effects. Congress's recent ad hoc appropriations do not allow long-term planning and ongoing monitoring and maintenance. Investing in water infrastructure will lower health care costs and create American jobs. Delaying necessary upgrades will only increase the costs of improvements over time.",
Arsenic,2278957,"The effect of plasma reactions on arsenic measurement by ICP spectrometry Abstract: Inductively coupled plasma mass spectrometry (ICP-MS) is of great value to researchers concerned with inorganic analytical chemistry as well as to engineers performing elemental analysis. However, the effects of the plasma reactions on ICP spectrometry are still incompletely understood and they sometimes introduce severe problems for measurements, such as spectral interferences. When we determine arsenic (As) by ICP-MS or ICP-AES, we observe two interesting plasma phenomena; one is the incoherent molecular formation (IMF) effect in the plasma, and the other the selective and partial oxygenation of ions with O2 gas in a dynamic reaction cell. The mechanisms of the IMF effect and selective oxygenation of As with a reaction gas were investigated and the techniques to remove their influence on As determination are discussed.",
Arsenic,1337628,"High-iron biosolids compost-induced changes in lead and arsenic speciation and bioaccessibility in co-contaminated soils Abstract: The safety of urban farming has been questioned due to the potential for contamination in urban soils. A laboratory incubation, a field trial, and a second laboratory incubation were conducted to test the ability of high-Fe biosolids-based composts to reduce the bioaccessibility of soil Pb and As in situ. Lead and As bioaccessibility were evaluated using an in vitro assay. Changes in Pb, As, and Fe speciation were determined on select samples after the second laboratory incubation using ?-X-ray fluorescence mapping followed by ?-X-ray absorption near-edge structure (XANES). A compost with Fe added to wastewater treatment residuals (Fe WTR compost) added to soils at 100 g/kg decreased Pb bioaccessibility in both laboratory incubations. Mixed results were observed for As. Composts tested in the field trial (Fe added as Fe powder or FeCl) did not reduce bioaccessible Pb, and limited reductions were observed in bioaccessible As. These composts had no effect on Pb bioaccessibility during the second laboratory incubation. Bulk XANES showed association of Pb with sulfates and carbonates in the control soil. ?-XANES for three points in the Fe WTR amended soil showed Pb present as Fe-sorbed Pb (88 and 100% of two points) and pyromorphite (12 and 53% of two points). Bulk XANES of the Fe WTR compost showed 97% of total Fe present as Fe. The results of this study indicate that addition of high-Fe biosolids compost is an effective means to reduce Pb accessibility only for certain types of Fe-rich materials.",
Arsenic,467929,"Arsenite and monomethylarsonous acid generate oxidative stress response in human bladder cell culture Abstract: Arsenicals have commonly been seen to induce reactive oxygen species (ROS) which can lead to DNA damage and oxidative stress. At low levels, arsenicals still induce the formation of ROS, leading to DNA damage and protein alterations. UROtsa cells, an immortalized human urothelial cell line, were used to study the effects of arsenicals on the human bladder, a site of arsenical bioconcentration and carcinogenesis. Biotransformation of As(III) by UROtsa cells has been shown to produce methylated species, namely monomethylarsonous acid [MMA(III)], which has been shown to be 20 times more cytotoxic. Confocal fluorescence images of UROtsa cells treated with arsenicals and the ROS sensing probe, DCFDA, showed an increase of intracellular ROS within five min after 1 mu M and 10 mu M As(III) treatments. In contrast, 50 and 500 nM MMA(III) required pretreatment for 30 min before inducing ROS. The increase in ROS was ameliorated by preincubation with either SOD or catalase. An interesting aspect of these ROS detection studies is the noticeable difference between concentrations of As(III) and MMA(III) used, further supporting the increased cytotoxicity of MMA(III), as well as the increased amount of time required for MMA(Ill) to cause oxidative stress. These arsenical-induced ROS produced oxidative DNA damage as evidenced by an increase in 8-hydroxyl-2'-deoxyguanosine (8-oxo-dG) with either 50 nM or 5 mu M MMA(III) exposure. These findings provide support that MMA(III) cause a genotoxic response upon generation of ROS. Both As(III) and MMA(III) were also able to induce Hsp70 and MT protein levels above control, showing that the cells recognize the ROS and respond. As(III) rapidly induces the formation of ROS, possibly through it oxidation to As(V) and further metabolism to MMA(III)/(V). These studies provide evidence for a different mechanism of MMA(III) toxicity, one that MMA(III) first interacts with cellular components before an ROS response is generated, taking longer to produce the effect, but with more substantial harm to the cell. (c) 2006 Elsevier Inc. All rights reserved.",
Arsenic,2347596,"Maternal Urinary Iodine Concentration up to 1.0 mg/L Is Positively Associated with Birth Weight, Length, and Head Circumference of Male Offspring Abstract: Adequate iodine status in early life is crucial for neurodevelopment. However, little is known about the effects of maternal iodine status during pregnancy on fetal growth. The present study investigated the potential impact of maternal iodine status during pregnancy on offspring birth size. This large prospective cohort study was nested in a Bangladeshi population-based randomized supplementation trial in pregnant women [MINIMat (Maternal and Infant Nutrition Interventions in Matlab)]. Urine samples obtained at 8 wk of gestation from 1617 women were analyzed for iodine and other elements, such as arsenic and cadmium, using inductively coupled plasma mass spectrometry. Anthropometric measurements at birth included weight, length, and head and chest circumference. Maternal urinary iodine concentrations (UICs) ranged from 0.020 to 10 mg/L, with a median of 0.30 mg/L. Below ?1.0 mg/L, UIC was significantly positively associated with birth weight and length. Birth weight and length increased by 9.3 g (95% CI: 2.9, 16) and 0.042 cm (95% CI: 0.0066, 0.076), respectively, for each 0.1-mg/L increase in maternal UIC. No associations were observed between UIC and head or chest circumference. When we stratified the analyses by newborn sex, the positive associations between maternal UIC (&lt;1 mg/L) and measurements of size at birth were restricted to boys, with no evidence in girls. Among boys, the mean weight, length, and head circumference increased by 70 g (P = 0.019), 0.41 cm (P = 0.013), and 0.28 cm (P = 0.031) for every 0.5-mg/L increase in maternal UIC. Maternal iodine status was positively associated with weight, length, and head circumference in boys up to ?1 mg/L, which is well above the recommended maximum concentration of 0.5 mg/L. The associations leveled off at UIC ? 1 mg/L. Our findings support previous conclusions that the advantages of correcting potential iodine deficiency outweigh the risks of excess exposure.",
Arsenic,1519043,"Subchronic exposure to arsenic disturbed the biogenic amine neurotransmitter level and the mRNA expression of the synthetase in mice brains Abstract: Little is known about the influence of arsenic (As) exposure on monoamine neurotransmitters and the underlying mechanisms, although arsenic toxicity on the central nervous system has been well documented. In the present study, the levels of norepinephrine (NE), dopamine (DA), and serotonin (5-HT) were determined by HPLC in cerebrum and cerebellum of mice exposed to 1, 2 and 4 ppm As2O3 through drinking water for 60 days. The ultra-structure change of vesicles in synapses of mice brains was observed by transmission electron microscopy; the mRNA expressions of dopamine beta hydroxylase (DBH), tyrosine hydroxylase (TH) and trptophan hydroxylase (TPH) as NE, DA and 5-HT synthetases were quantitatively by real time RT-PCR. It was shown that the concentrations of NE, DA and 5-HT in the cerebrum or cerebellum of mice exposed to As were significantly lower than those in the control group. The number of synaptic vesicles significantly decreased in the brain of mice exposed to As. Moreover, the expressions of TH, TPH and DBH genes were significantly lower in the brains of mice exposed to As than those in the controls. These results suggested that subchronic exposure to As might decrease the concentrations of the three monoamine neurotransmitters in mouse brain and downregulate TH, TPH and DBH gene expressions. It was also indicated that the decreased concentrations of the three monoamine neurotransmitters in the brain might be related to the down-regulated gene expressions of these synthetases by As.",
Arsenic,1508512,"Structural and functional genomics of plasmid pSinA of Sinorhizobium sp. M14 encoding genes for the arsenite oxidation and arsenic resistance Abstract: Plasmid pSinA of Sinorhizobium sp. M14 (Alphaproteobacteria) is the first described, natural, self-transferable plasmid harboring a complete set of genes for oxidation of arsenite. Removal of this plasmid from cells of the host strain caused the loss of resistance to arsenic and heavy metals (Cd, Co, Zn and Hg) and abolished the ability to grow on minimal salt medium supplemented with sodium arsenite as the sole energy source. Plasmid pSinA was introduced into other representatives of Alphaproteobacteria which resulted in acquisition of new abilities concerning arsenic resistance and oxidation, as well as heavy metals resistance. Microcosm experiments revealed that plasmid pSinA can also be transferred via conjugation into other indigenous bacteria from microbial community of As-contaminated soils, including representatives of Alpha- and Gammaproteobacteria. Analysis of &quot;natural&quot; transconjugants showed that pSinA is functional (expresses arsenite oxidase) and is stably maintained in their cells after approximately 60 generations of growth under nonselective conditions. This work clearly demonstrates that pSinA is a self-transferable, broad-host-range plasmid, which plays an important role in horizontal transfer of arsenic metabolism genes.",
Arsenic,2345700,"Composite nanofibers prepared from metallic iron nanoparticles and polyaniline: High performance for water treatment applications Abstract: Presented here is a simple preparation of metallic iron nanoparticles, supported on polyaniline nanofibers at room temperature. The preparation is based on polymerization of interconnected nanofibers by rapid mixing of the aniline monomer with Fe(III) chloride as the oxidant, followed by reductive deposition of Fe(0) nanoparticles, using the polymerization by-products as the Fe precursor. The morphology and other physico-chemical properties of the resulting composite were characterized by scanning and transmission electron microscopy, Brunauer-Emmett-Teller method, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and vibrating-sample magnetometry. The composite fibers were 80-150 nm in diameter and exhibited the expected ferromagnetic behavior. The composite rapidly and efficiently removed As(V), Cr(VI), and also Congo red dye, from aqueous solutions suggesting their usefulness for removal of toxic materials from wastewater. The composite fibers have high capacity for toxin removal: 42.37 mg/g of As(V), 434.78 mg/g of Cr(VI), and 243.9 mg/g of Congo red. The fibers are easily recovered from fluids by exploiting their ferromagnetic properties.",
Arsenic,1019952,"Development and application of a robust speciation method for determination of six arsenic compounds present in human urine Abstract: Six arsenic species [arsenate, arsenite, arsenocholine, arsenobetaine, monomethyl arsonic acid, and dimethyl arsinic acid] present in human urine were determined using ion-exchange chromatography combined with inductively coupled plasma mass spectrometry (IC-ICP-MS). Baseline separation was achieved for all six species as well as for the internal standard (potassium hexahydroxy antimonate V) in a single chromatographic run of less than 30 min, using an ammonium carbonate buffer gradient (between 10 and 50 mM) at ambient temperature, in conjunction with cation- and anion-exchange columns in series. The performance of the method was evaluated with respect to linearity, precision, accuracy, and detection limits. This method was applied to determine the concentration of these six arsenic species in human urine samples (n = 251) collected from a population-based exposure assessment survey. Method precision was demonstrated by the analysis of duplicate samples that were prepared over a 2-year analysis period. Total arsenic was also determined for the urine samples using flow injection analysis coupled to ICP-MS. The summed concentration of the arsenic species was compared with the measured arsenic total to demonstrate mass balance.",
Arsenic,1677579,"Case-control study of arsenic in drinking water and kidney cancer in uniquely exposed Northern Chile Abstract: Millions of people worldwide are exposed to arsenic in drinking water. The International Agency for Research on Cancer has concluded that ingested arsenic causes lung, bladder, and skin cancer. However, a similar conclusion was not made for kidney cancer because of a lack of research with individual data on exposure and dose-response. With its unusual geology, high exposures, and good information on past arsenic water concentrations, northern Chile is one of the best places in the world to investigate the carcinogenicity of arsenic. We performed a case-control study in 2007-2010 of 122 kidney cancer cases and 640 population-based controls with individual data on exposure and potential confounders. Cases included 76 renal cell, 24 transitional cell renal pelvis and ureter, and 22 other kidney cancers. For renal pelvis and ureter cancers, the adjusted odds ratios by average arsenic intakes of <400, 400-1,000, and >1,000 µg/day (median water concentrations of 60, 300, and 860 µg/L) were 1.00, 5.71 (95% confidence interval: 1.65, 19.82), and 11.09 (95% confidence interval: 3.60, 34.16) (Ptrend < 0.001), respectively. Odds ratios were not elevated for renal cell cancer. With these new findings, including evidence of dose-response, we believe there is now sufficient evidence in humans that drinking-water arsenic causes renal pelvis and ureter cancer.",
Arsenic,1339955,"Identification of metabolic pathways involved in the biosynthesis of flavor compound 3-methylbutanal from leucine catabolism by Carnobacterium maltaromaticum LMA 28 Abstract: Carnobacterium maltaromaticum strains are widely found in food including fish, meat and some dairy products. Producing a malty/chocolate like aroma due to 3-methylbutanal from the catabolism of leucine is a general characteristic of this species. In this study, we investigated metabolic routes responsible for the biosynthesis of this flavor compound from the catabolism of leucine in C. maltaromaticum LMA 28, a strain isolated from mold ripened soft cheese. Depending on the lactic acid bacterium, leucine can be converted into 3-methylbutanal following two possible metabolic pathways: either directly by ?-ketoacid decarboxylase (KADC) pathway or indirectly by ?-ketoacid dehydrogenase (KADH) pathway. Both KADC (41.0±3.0 nmol/mg protein/min) and KADH (1.43±0.62 nmol/mg protein/min) activities were detected and determined in vitro in C. maltaromaticum LMA 28. C. maltaromaticum LMA 28 slightly reduced the production of 3-methylbutanal from leucine in the presence of a specific inhibitor of KADH enzyme complex, i.e. sodium meta-arsenite, suggesting that both pathways were involved in vivo in leucine catabolism. Moreover the presence of genes encoding aminotransferase, glutamate dehydrogenase, ?-ketoacid decarboxylase, ?-ketoacid dehydrogenase and aldehyde dehydrogenase was confirmed. C. maltaromaticum is then the first lactic acid bacterium in which presence of both metabolic routes responsible for the biosynthesis of 3-methylbutanal from leucine catabolism was confirmed in vitro and in vivo as well.",
Arsenic,627469,"Dimethylarsine and trimethylarsine are potent genotoxins in vitro Abstract: The mechanism of arsenic carcinogenesis is unclear. A complicating factor receiving increasing attention is that arsenic is biomethylated to form various metabolites. Eleven different arsenicals were studied for in vitro genotoxicity to supercoiled DNA (pBR 322 and phiX174). Five arsenicals showed various degrees of positivity-monomethylarsonous acid, dimethylarsinous acid, monomethylarsine, dimethylarsine, and trimethylarsine. Supercoiled DNA, blotted on nitrocellulose filter paper, was exposed to gaseous arsines by suspending the filter paper above aqueous reaction mixtures of sodium borohydride and an appropriate arsenical. All three methylated arsines damaged DNA; inorganic arsine did not. Arsines were generated in situ in reaction mixtures containing DNA by reaction of sodium borohydride with arsenite, monomethylarsonous acid, dimethylarsinous acid, and trimethylarsine oxide, at pH 8.0. Both dimethylarsine and trimethylarsine (generated from 200 micro M dimethylarsinous acid and trimethylarsine oxide, respectively) damaged DNA in less than 30 min. Under certain conditions, the two most potent genotoxic arsines, trimethylarsine and dimethylarsine, are about 100 times more potent than dimethylarsinous acid (the most potent genotoxic arsenical previously known). There was no evidence to suggest that anything other than the arsines caused the DNA damage. Possible models for the biological production of arsines were examined. The coenzymes, NADH and NADPH, are biological hydride donors. When NADH or NADPH (5 mM) were incubated with dimethylarsinous acid (0-2 mM) for 2 h, DNA damage was increased by at least 10-fold. A possible explanation for this result is that these compounds react with dimethylarsinous acid to generate dimethylarsine. DNA was incubated with a dithiol compound, dithioerythritol (5 mM), and trimethylarsine oxide (0.5 mM) for 2 h, and the reduction of trimethylarsine oxide to trimethylarsine resulted in DNA damage.",
Arsenic,1018315,"Modulation of early stress-related biomarkers in cytoplasm by the antioxidants silymarin and quercetin using a cellular model of acute arsenic poisoning Abstract: Several pathologies (e.g. cancer and diabetes) are increased in arsenic-exposed populations, with oxidative stress being a major toxicological mechanism. Since the flavonoids silymarin (S) and quercetin (Q) are antioxidants and may protect cells, it would be valuable to develop a model which allows assessing the potential of xenobiotic against arsenic cytotoxicity in an efficient and rapid way. Thus, the oxidant production [e.g. reactive oxygen species and reactive nitrogen species (RNS)], the molecular parameters of biological response [e.g. plasma membrane composition, actin microfilaments and activated diphosphorilated c-Jun N-terminal kinase (JNK)] and cellular viability were determined in CHO-K1 cells treated with arsenite (As), S and Q. Arsenic caused loss of the cellular viability in a time-dependent manner. This effect was accompanied by a lipid hydroperoxide (LHP) formation, with no RNS induction or ganglioside content changes being found. Both flavonoids counteracted oxidative damage. Despite all treatments had unspecific responses on nitrite cellular release along the time, there was no relation between them and the cellular viability. Arsenic induced cytoplasmic microfilament rearrangement (tight perinuclear distribution with projections, stress fibres and pseudopodia) which was reversed by S. Also, activated JNK showed a similar distribution to actin. Contrarily, Q caused a dysmorphic granular pattern, thus behaving as a toxic agent. Summing up, toxic levels of arsenic disturb the redox homeostasis with LHP induction and early triggering of stress responses in cytoskeleton and cell signalling. Using the proposed model, only S showed to protect cells from arsenical cytotoxicity without own toxic properties. Thus, S might be considered for modulation of the human arsenic susceptibility.",
Arsenic,1936121,"Analysis for remedial alternatives of unregulated municipal solid waste landfills leachate-contaminated groundwater Abstract: A groundwater flow and solute transport model was developed using Visual Modflow for forecasting contaminant transport and assessing effects of remedial alternatives based on a case study of an unregulated landfill leachate-contaminated groundwater in eastern China. The results showed that arsenic plume was to reach the pumping well in the downstream farmland after eight years, and the longest lateral and longitudinal distance of arsenic plume was to reach 200 m and 260 m, respectively. But the area of high concentration region of arsenic plume was not to obviously increase from eight years to ten years and the plume was to spread to the downstream river and the farmland region after 20 years; while the landfill’s ground was hardened, the plume was not to reach the downstream farmland region after eight years; when the pumping well was installed in the plume downstream and discharge rate was 200m3/d, the plume was to be effectively restrained; for leakage-proof barriers, it might effectively protect the groundwater of sensitive objects within an extent time range. But for the continuous point source, the plume was still to circle the leakage-proof barrier; when discharge rate of drainage ditches was 170.26 m3/d, the plume was effectively controlled; the comprehensive method combining ground-harden with drainage ditches could get the best effect in controlling contaminant diffusion, and the discharge rate was to be reduced to 111.43 m3/d. Therefore, the comprehensive remedial alternative combining ground-harden with drainage ditch will be recommended for preventing groundwater contamination when leachate leakage has happened in unregulated landfills.",
Arsenic,2347747,Source and Characteristic of Fluorescence Humic Substances in Arsenic Polluted Groundwater of Bangladesh Abstract: Fluorescence characteristic and molecular size distribution of groundwater humic substance (HS) from arsenic contaminated (AsCon) and uncontaminated (nAsCon) areas of Bangladesh indicated that source of HS in aquifers are different with specific molecular size distributions. AsCon area showed signature of microbial degraded HS with small molecular size (0.65 KDa) whereas nAsCon area has minor signature of microbial originated HS with relatively high molecular size (1.24 KDa).,
Arsenic,1024521,"Is colon cancer mortality related to arsenic exposure? Abstract: Arsenic has been well documented as the major risk factor for blackfoot disease (BFD), a unique peripheral vascular disease that was endemic to the southwestern coast of Taiwan, where residents consumed high-arsenic artesian well water for more than 50 yr. Chronic arsenic exposure was also reported to be associated with increased mortality attributed to colon cancer. A tap-water supply system was implemented in the early 1960s in the BFD-endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study was to determine whether colon cancer mortality decreased after the improvement of the drinking-water supply system through elimination of arsenic ingestion from artesian well water. Standardized mortality ratios (SMRs) for colon cancer were calculated for the BFD-endemic area for the years 1971-2006. Results showed that mortality due to colon cancer declined in males, but not in females, gradually after the improvement of drinking-water supply system. Based on the reversibility criterion, the association between arsenic exposure and colon cancer incidence is likely to be causal for males but not females. The possibility that our results may be due to chance should be considered; however, gender-specific differences in arsenic metabolism may be a critical factor.",
Arsenic,2345631,"Electrochemical quantification of iodide ions in synthetic urine using silver nanoparticles: a proof-of-concept Abstract: Typical urinary iodide concentrations range from 0.3 ?M to 6.0 ?M. The conventional analytical method is based on the Sandell-Kolthoff reaction. It involves the toxic reagent, arsenic acid, and a waiting time of 30 minutes for the iodide ions to reduce the cerium(iv) ions. In the presented work, an alternative fast electrochemical method based on a silver nanoparticle modified electrode is proposed. Cyclic voltammetry was performed with a freshly modified electrode in presence of iodide ions and the voltammetric peaks corresponding to the oxidation of silver to silver iodide and the reverse reaction were recorded. The peak height of the reduction signal of silver iodide was used to plot a calibration line for the iodide ions. Two calibration plots for the iodide ions were obtained, one in 0.1 M sodium nitrate (a chloride-ion free environment to circumvent any interference from the other halides) and another in synthetic urine (which contains 0.2 M KCl). In both of the calibration plots, linear relationships were found between the reduction peak height and the iodide ion concentration of 0.3 ?M to 6.0 ?M. A slope of 1.46 × 10(-2) A M(-1) and a R(2) value of 0.999 were obtained for the iodide detection in sodium nitrate. For the synthetic urine experiments, a slope of 3.58 × 10(-3) A M(-1) and a R(2) value of 0.942 were measured. A robust iodide sensor with the potential to be developed into a point-of-care system has been validated.",
Arsenic,627285,"Arsenic in drinking water and incidence of urinary cancers Abstract: The associations between arsenic ingestion and cancers of the bladder and kidney have been documented in Taiwan. To evaluate further such associations for urinary cancers of various cell types, we conducted an ecologic study encompassing 243 townships using cancer registry data of patients diagnosed between 1980 and 1987. We used the proportions of wells with various specified arsenic levels in each township as indicators of exposure and evaluated the effects of urbanization and smoking by an urbanization index and the number of cigarettes sold per capita. In both genders, we observed associations of high arsenic levels in drinking water with transitional cell carcinomas of the bladder, kidney, and ureter and all urethral cancers combined. We also observed such associations in adenocarcinomas of the bladder in males, but not in squamous cell carcinomas of the bladder or renal cell carcinomas or nephroblastomas of the kidney. There was also a positive association between the urbanization index and transitional cell carcinomas of the ureter in males. The number of cigarettes sold per capita was not a good predictor for urinary cancers. The results indicate that the carcinogenicity of arsenic may be cell type specific.",
Arsenic,1350709,Development of Inductively Coupled Plasma Atomic Emission Spectrometry for Arsenic Determination in Wine Abstract: ,
Arsenic,58553,"Interindividual variation in the metabolism of arsenic in cultured primary human hepatocytes Abstract: Liver is a prime site for conversion of inorganic arsenic (iAs) to methylated metabolites, including methylarsenicals (MAs) and dimethylarsenicals (DMAs). To assess interindividual variation in the capacity of liver to metabolize iAs, we examined the metabolic fate of arsenite (iAsIII) in normal primary human hepatocytes obtained from eight donors and cultured under standard conditions. Methylation rates, yields, and distribution of arsenicals were determined for hepatocytes exposed to 0.3û30 nmol of iAsIII/mg of protein for 24 h. Although the accumulation of arsenic (As) by cells was a linear function of the initial concentration of iAsIII in culture, the concentration of As retained in cells varied several fold among donors. DMAs was the major methylated metabolite found in cultures exposed to low concentrations of iAsIII; at higher concentrations, MAs was always predominant. Maximal rates for methylation of iAsIII were usually attained at 3 or 9 nmol of iAsIII/mg of protein and varied about 7-fold among donors. For most donors, the methylation rate decreased at the highest iAsIII concentrations. MAs was the major methylated metabolite retained in cells regardless of exposure level. DMAs was the major methylated metabolite found in medium. The interindividual differences in rates for iAsIII methylation were not strictly associated with variations in basal mRNA levels for cyt19, an As-methyltransferase. Analysis of the coding sequence of cyt19 identified one heterozygote with Met287Thr mutation in a single allele. Thus, genetic polymorphism of cyt19 along with other cellular factors is likely responsible for interindividual differences in the capacity of primary human hepatocytes to retain and metabolize iAsIII.",
Arsenic,1365227,"Two collagen-binding proteins, osteonectin and HSP47, are coordinately induced in transformed keratinocytes by heat and other stresses Abstract: pSE48 was one of six clones selected by differential colony hybridization as a cDNA coding for mRNA expressed in parietal endoderm-like F9 cells and not in primitive endoderm-like F9 cells. It was sequenced and identified as a segment of mouse osteonectin (SPARC) cDNA. We found osteonectin to be heat-inducible in some cells. Expression and secretion of osteonectin were then investigated using mouse (Pam 212) and human (HSC-1) keratinocyte cell lines. Both the mRNA levels and the secretion of osteonectin increased concurrently when Pam and HSC-1 cells cultured in low calcium medium were exposed to various stresses including heat shock and treatment with sodium arsenite or L-azetidine-2-carboxylic acid. Another collagen-binding stress protein, HSP47, was also found to be expressed, synthesized, and stress-inducible in the keratinocyte cell line. The degree of HSP47 induction by various stresses was not so prominent as that of HSP70 but greater than that of osteonectin. The time courses of osteonectin and HSP47 induction by heat shock were similar to each other and distinct from HSP70; they were slower and more persistent than HSP70. We identified a heat shock element-like sequence in the promoter region of the mouse and bovine osteonectin genes. This sequence might participate in the stress induction of osteonectin. Thus, osteonectin and HSP47 share another common feature, stress-inducibility, as well as collagen-binding capacity and inducibility through differentiation, although they are quite distinct in their amino acid sequence and distribution.",
Arsenic,1327809,"Cellular stress inhibits vascular smooth muscle relaxation Abstract: <strong>PURPOSE: </strong>Cellular stress has been shown to induce a group of proteins called heat shock proteins (HSPs). Recent evidence suggests that a group of small HSPs may modulate vascular smooth muscle contraction (HSP27) and/or relaxation (HSP20). In this investigation, we hypothesized that cellular stress would alter contraction and/or relaxation of intact vascular smooth muscles and would lead to changes in the induction and/or phosphorylation of the small HSPs.<br /><br /><strong>METHODS: </strong>Bovine carotid arteries were obtained from an abattoir, and physiologic contractile responses were determined in a muscle bath. Phosphorylation state-specific antibodies were produced and characterized against HSP27. Phosphorylation events were determined with phosphorylation state-specific antibodies or whole-cell phosphorylation and two-dimensional gel electrophoresis.<br /><br /><strong>RESULTS: </strong>Cellular stress induced by arsenite or heat shock did not alter basal tone or the magnitude of contractions induced by serotonin or high extracellular potassium chloride. However, cellular stress led to inhibition of forskolin and sodium nitroprusside-induced vasorelaxation. This impaired vasorelaxation was associated with increases in the phosphorylation of HSP27 and decreases in forskolin-induced phosphorylation of HSP20.<br /><br /><strong>CONCLUSION: </strong>Cellular stress, which leads to increases in the phosphorylation of HSP27, inhibits cyclic nucleotide-dependent vascular relaxation and cyclic nucleotide-dependent increases in the phosphorylation of HSP20.",
Arsenic,2279444,"In silico and in vivo studies of molecular structures and mechanisms of AtPCS1 protein involved in binding arsenite and/or cadmium in plant cells Abstract: This paper reports a continuation of our previous research on the phytochelatin synthase1 (PCS1) gene involved in binding and sequestration of heavy metals or metalloids in plant cells [1]. Construction of a 3D structure of the Arabidopsis thaliana PCS1 protein and prediction of gene function by employing iterative implementation of the threading assembly refinement (I-TASSER) revealed that PC ligands (3GC-gamma-glutamylcysteine) and Gln50, Pro53, Ala54, Tyr55, Cys56, Ile102, Gly161, His162, Phe163, Asp204 and Arg211 residues are essential for formation of chelating complex with cadmium (Cd(2+)) or arsenite (AsIII). This finding suggests that the PCS1 protein might be involved in the production of the enzyme phytochelatin synthase, which might in turn bind, localize, store or sequester heavy metals in plant cells. For validation of the in silico results, we included a T-DNA tagged mutant of Arabidopsis thaliana, SAIL_650_C12, (mutation in AtPCS1 gene) in our investigation. Furthermore, using reverse transcriptase PCR we confirmed that the mutant does not express the AtPCS1 gene. Mutant plants of SAIL_650_C12 were exposed to various amounts of cadmium (Cd(2+)) and arsenite (AsIII) and the accumulation of these toxic metals in the plant cells was quantified spectrophotometrically. The levels of Cd(2+) and AsIII accumulation in the mutant were approximately 2.8 and 1.6 times higher, respectively, than that observed in the wild-type controlled plants. We confirmed that the results obtained in in silico analyses complement those obtained in in vivo experiments.",
Arsenic,1326999,"Sodium arsenite enhances copper accumulation in human lung adenocarcinoma cells Abstract: In this report, we found that arsenite-resistant human lung adenocarcinoma cells, CL3R15, were more susceptible to CuCl2 than the parental CL3 cells. With the aid of atomic absorption spectrophotometry, we observed that CL3R15 cells accumulated more copper than CL3 cells. We further demonstrated that sodium arsenite treatment resulted in a dose-dependent increase of copper accumulation in the parental CL3 cells. In contrast, copper did not alter the levels of intracellular arsenite in CL3 cells treated in combination with sodium arsenite and CuCl2. Pretreatment of CL3 cells with sodium arsenite resulted in a significant increase of copper accumulation and cytotoxicity. These results indicate that intracellular copper accumulation is enhanced by arsenite. However, arsenite-enhanced copper accumulation was not observed in two fibroblastic cells, GM00220 and GM03700, derived from Menkes patients. The Menkes gene encodes a membrane pump responsible for copper exportation. Our results suggest that Menkes protein is a potential target of arsenite.",
Arsenic,1339125,"Arsenic mineral dissolution and possible mobilization in mineral-microbe-groundwater environment Abstract: Arsenic (As) is widely distributed in the nature as ores or minerals. It has been attracted much attention for the global public health issue, especially for groundwater As contamination. The aim of this study was to elucidate the characteristics of microbes in groundwater where As-minerals were dissolved. An ex situ experiment was conducted with 7 standard As-minerals in bacteria-free groundwater and stored in experimental vessels for 1 year without supplementary nutrients. The pH (6.7-8.4) and Eh(S.H.E.) (24-548mV) changed between initial (0 day) and final stages (365 days) of experiment. The dissolution of As was detected higher from arsenolite (4240±8.69mg/L) and native arsenic (4538±9.02mg/L), whereas moderately dissolved from orpiment (653±3.56mg/L) and realgar (319±2.56mg/L) in compare to arsenopyrite (85±1.25mg/L) and tennantite (3±0.06mg/L). Optical microscopic, scanning electron microscopic observations and flurometric enumeration revealed the abundance of As-resistant bacillus, coccus and filamentous types of microorganisms on the surface of most of As-mineral. 4'-6-Diamidino-2-phenylindole (DAPI)-stained epifluorescence micrograph confirmed the presence of DNA and carboxyfluorescein diacetate (CFDA) staining method revealed the enzymatically active bacteria on the surface of As-minerals such as in realgar (As(4)S(4)). Therefore, the microbes enable to survive and mobilize the As in groundwater by dissolution/bioweathering of As-minerals.",
Arsenic,1342499,"Phosphorylation of eIF2 directs ATF5 translational control in response to diverse stress conditions Abstract: Phosphorylation of eukaryotic initiation factor 2 (eIF2) is an important mechanism regulating global and gene-specific translation in response to different environmental stresses. Central to the eIF2 kinase response is the preferential translation of ATF4 mRNA, encoding a transcriptional activator of genes involved in stress remediation. In this report, we addressed whether there are additional transcription factors whose translational expression is regulated by eIF2 kinases. We show that the expression of the basic zipper transcriptional regulator ATF5 is induced in response to many different stresses, including endoplasmic reticulum stress, arsenite exposure, and proteasome inhibition, by a mechanism requiring eIF2 phosphorylation. ATF5 is subject to translational control as illustrated by the preferential association of ATF5 mRNA with large polyribosomes in response to stress. ATF5 translational control involves two upstream open reading frames (uORFs) located in the 5'-leader of the ATF5 mRNA, a feature shared with ATF4. Mutational analyses of the 5'-leader of ATF5 mRNA fused to a luciferase reporter suggest that the 5'-proximal uORF1 is positive-acting, allowing scanning ribosomes to reinitiate translation of a downstream ORF. During non-stressed conditions, when eIF2 phosphorylation is low, ribosomes reinitiate translation at the next ORF, the inhibitory uORF2. Phosphorylation of eIF2 during stress delays translation reinitiation, allowing scanning ribosomes to bypass uORF2, and instead translate the ATF5 coding region. In addition to translational control, ATF5 mRNA levels are significantly reduced in ATF4-/- mouse embryo fibroblasts, suggesting that ATF4 contributes to basal ATF5 transcription. These results demonstrate that eIF2 kinases direct the translational expression of multiple transcription regulators by a mechanism involving delayed translation reinitiation.",
Arsenic,2149179,"NADPH oxidase-mitochondria axis-derived ROS mediate arsenite-induced HIF-1? stabilization by inhibiting prolyl hydroxylases activity Abstract: Arsenic exposure has been shown to induce hypoxia inducible factor 1? (HIF-1?) accumulation, however the underlying mechanism remains unknown. In the present study, we tested the hypothesis that arsenic exposure triggered the interaction between NADPH oxidase and mitochondria to promote reactive oxygen species (ROS) production, which inactivate prolyl hydroxylases (PHDs) activity, leading to the stabilization of HIF-1? protein. Exposure of human immortalized liver cell line HL-7702 cells to arsenite induced HIF-1? accumulation in a dose-dependent manner, which was abolished by SOD mimetic MnTMPyP. Inhibition of NADPH oxidase with diphenyleneiodonium chloride (DPI) or inhibition of mitochondrial respiratory chain with rotenone significantly blocked arsenite-induced ROS production, and the mitochondria appeared to be the major source of ROS production. Arsenite treatment inhibited HIF-1? hydroxylation by prolyl hydroxylases (PHDs) and increased HIF-1? stabilization, but did not affect HIF-1? mRNA expression and Akt activation. Supplementation of ascorbate or Fe(II) completely abolished arsenite-induced PHDs inhibition and HIF-1? stabilization. In conclusion, these results define a unique mechanism of HIF-1? accumulation following arsenic exposure, that is, arsenic activates NADPH oxidase-mitochondria axis to produce ROS, which deplete intracellular ascorbate and Fe(II) to inactivate PHDs, leading to HIF-1? stabilization.",
Arsenic,1337638,"Biosorption of arsenic (III) from aqueous solution by living cells of Bacillus cereus Abstract: In this work, removal of arsenic (III) from aqueous solution by living cells (Bacillus cereus), biosorption mechanism, and characterization studies have been reported. B. cereus cell surface was characterized using SEM-EDX and FTIR. Dependence of biosorption on pH of the solution, biosorbent dose, initial arsenic (III) concentration, contact time, and temperature had been studied to achieve optimum condition. The maximum biosorption capacity of living cells of B. cereus for arsenic (III) was found to be 32.42 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30?±?2 °C. Biosorption data of arsenic (III) are fitted to linearly transformed Langmuir isotherm with R (2) (correlation coefficient)?&gt;?0.99. The pseudo-second-order model description of the kinetics of arsenic (III) is successfully applied to predict the rate constant of biosorption. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) onto B. cereus biomass. The arsenic (III) ions are desorbed from B. cereus using both 1 M HCl and 1 M HNO(3).",
Arsenic,195937,"DNA-protein cross-links produced by various chemicals in cultured human lymphoma cells Abstract: Chemicals such as cis-platinum, formaldehyde, chromate, copper, and certain arsenic compounds have been shown to produce DNA-protein cross-links in human in vitro cell systems at high doses, such as those in the cytotoxic range. Thus far there have only been a limited number of other chemicals evaluated for their ability to produce cross-links. The purpose of the work described here was to evaluate whether select industrial chemicals can form DNA-protein cross-links in human cells in vitro. We evaluated acetaldehyde, acrolein, diepoxybutane, paraformaldehyde, 2-furaldehyde, propionaldehyde, chloroacetaldehyde, sodium arsenite, and a deodorant tablet [Mega Blue; hazardous component listed as tris(hydroxymethyl)nitromethane]. Short- and long-term cytotoxicity was evaluated and used to select appropriate doses for in vitro testing. DNA-protein cross-linking was evaluated at no fewer than three doses and two cell lysate washing temperatures (45 and 65 degrees C) in Epstein-Barr virus (EBV) human Burkitt's lymphoma cells. The two washing temperatures were used to assess the heat stability of the DNA-protein cross-link, 2-Furaldehyde, acetaldehyde, and propionaldehyde produced statistically significant increases in DNA-protein cross-links at washing temperatures of 45 degrees C, but not 65 degrees C, and at or above concentrations of 5, 17.5, and 75 mM, respectively. Acrolein, diepoxybutane, paraformaldehyde, and Mega Blue produced statistically significant increases in DNA-protein cross-links washed at 45 and 65 degrees C at or above concentrations of 0.15 mM, 12.5 mM, 0.003%, and 0.1%, respectively. Sodium arsenite and chloroacetaldehyde did not produce significantly increased DNA-protein cross-links at either temperature nor at any dose tested. Excluding paraformaldehyde and 2-furaldehyde treatments, significant increases in DNA-protein cross-links were observed only at doses that resulted in complete cell death within 4 d following dosing. This work demonstrates that DNA-protein cross-links can be formed in vitro following exposure to a variety of industrial compounds and that most cross-links are formed at cytotoxic concentrations.",
Arsenic,1797782,"Inorganic arsenic exposure induces E2F-dependent G0/G1 arrest via an increase in retinoblastoma family protein p130 in B-cell lymphoma A20 cells Abstract: Inorganic arsenic exerts toxic effect on multiple systems including the immune system. We previously showed in a study on mouse thymocytes and B-cell lymphoma A20 cells that arsenite induces cell cycle arrest at G0/G1 by suppressing expression of E2F-target genes. In this study, we furthermore investigated the involvement of retinoblastoma (RB) family proteins in E2F-dependent cell cycle arrest by arsenite. Arsenite exposure of A20 cells was showed to increase the protein level of p130, a RB family member, without changing the mRNA level. Suppression of arsenite-induced p130 by siRNA reduced the G0/G1 phase, indicating that p130 accumulation is responsible for arsenite-induced G0/G1 arrest. The accumulated p130 was shown to increase the p130 complex with E2F4, a transcription-suppressing E2F. Comparison by Western blotting of arsenite-induced p130 and p130 accumulated by a proteasome inhibitor suggested that arsenite-induced p130 is hypophosphorylated and hypoubiquitinated and refractory to proteasome-dependent degradation. We also showed that arsenite increases mRNA and protein of p16(INK4a) , an inhibitor of CDK4/6 that phosphorylates p130. Down-regulation of arsenite-induced p16(INK4a) by siRNA suppressed the p130 accumulation. We propose a novel mechanism in which arsenite inhibits phosphorylation/ubiquitin-dependent proteasome degradation of p130 by inducing p16(INK4a) and the accumulated p130 causes cell cycle arrest with E2F4.",
Arsenic,1017205,"Identifying sources and assessing potential risk of heavy metals in soils from direct exposure to children in a mine-impacted city, Changsha, China Abstract: Heavy metal pollutants in soils can usually enter the human body and pose heath risks through a soil-crop-human body pathway (indirect exposure) or soil-human body pathway (direct exposure). Previous studies often neglected the direct exposure in human health risk assessment, especially for children. We collected surface soil samples from urban and suburb areas in Changsha City, China, to analyze the content ofAs, Cd, Hg, Ni, Pb, and Zn. A combination of principal component analysis, geostatistics, and triangulated irregular network (TIN) model was successfully used to discriminate the sources of heavy metals. The direct exposure method, sequential indicator simulation, and geographical information system (GIS) technologies were used to perform a health risk assessment of heavy metal exposure to children living in the study area. Results show that heavy metal contamination in Changsha may originate from coal usage and industrial activities. One thousand equiprobable realizations suggest that not all sites within the study area may be suitable for housing or allotments without remediation. Most high hazard indexes are located in the suburb and mining areas. Moreover, arsenic presents a high health risk in comparison with other elements. Compared with inhalation and dermal contact in direct soil exposure, soil ingestion is the largest contribution to potential health risks for children. This study indicates that we should attach great importance to the direct soil exposure for children's health.",
Arsenic,710821,"Arsenic exposure, dietary patterns, and skin lesion risk in Bangladesh: A prospective study Abstract: Dietary factors are believed to modulate arsenic toxicity, potentially influencing risk of arsenical skin lesions. The authors evaluated associations among dietary patterns, arsenic exposure, and skin lesion risk using baseline food frequency questionnaire data collected in the Health Effects of Arsenic Longitudinal Study (HEALS) in Araihazar, Bangladesh (2000-2009). They identified dietary patterns and estimated dietary pattern scores using factor analysis. Scores were tested for association with incident skin lesion risk and interaction with water arsenic exposure by using ?6 years of follow-up data (814 events among 9,677 individuals) and discrete time hazards models (adjusting for key covariates). The authors identified 3 clear dietary patterns: the ""gourd and root,"" ""vegetable,"" and ""animal protein"" patterns. The gourd and root pattern score was inversely associated with skin lesion risk (P(trend) = 0.001), with hazard ratios of 0.86, 0.73, and 0.69 for the second, third, and fourth highest quartiles. Furthermore, the association between water arsenic and skin lesion incidence was stronger among participants with low gourd and root scores (multiplicative P(interaction) < 0.001; additive P(interaction) = 0.05). The vegetable pattern and animal protein pattern showed similar but weaker associations and interactions. Eating a diet rich in gourds and root vegetables and increasing dietary diversity may reduce arsenical skin lesion risk in Bangladesh.",
Arsenic,1519004,"Systems biology and birth defects prevention: blockade of the glucocorticoid receptor prevents arsenic-induced birth defects Abstract: Background: The biological mechanisms by which environmental metals are associated with birth defects are largely unknown. Systems biology-based approaches may help to identify key pathways that mediate metal-induced birth defects as well as potential targets for prevention.Objectives: First, we applied a novel computational approach to identify a prioritized biological pathway that associates metals with birth defects. Second, in a laboratory setting, we sought to determine whether inhibition of the identified pathway prevents developmental defects.Methods: Seven environmental metals were selected for inclusion in the computational analysis: arsenic, cadmium, chromium, lead, mercury, nickel, and selenium. We used an in silico strategy to predict genes and pathways associated with both metal exposure and developmental defects. The most significant pathway was identified and tested using an in ovo whole chick embryo culture assay. We further evaluated the role of the pathway as a mediator of metal-induced toxicity using the in vitro midbrain micromass culture assay.Results: The glucocorticoid receptor pathway was computationally predicted to be a key mediator of multiple metal-induced birth defects. In the chick embryo model, structural malformations induced by inorganic arsenic (iAs) were prevented when signaling of the glucocorticoid receptor pathway was inhibited. Further, glucocorticoid receptor inhibition demonstrated partial to complete protection from both iAs- and cadmium-induced neurodevelopmental toxicity in vitro.Conclusions: Our findings highlight a novel approach to computationally identify a targeted biological pathway for examining birth defects prevention.",
Arsenic,2088316,"Atomic absorption spectrophotometric determination of trace amounts of arsenic and some heavy metals in their treatment technology by iron powder Abstract: Arsenic and heavy metals present in wastewater were determined before and after treatment on the adsorbent column is significant science in Vietnam. In this study, we used the available natural materials, it is powdered and Fe<sup>(0)</sup> yellow sand, MnO<sub>2</sub> powder under the granules used as adsorbent in the column. The survey materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM). These study showed that the material consists of magnetite Fe<sub>3</sub>O<sub>4</sub> 38.18%, hematite Fe<sub>2</sub>O<sub>3</sub> 12.73%, wuestite FeO 16.36% of the beneficial minerals for the adsorption of heavy metals. The results showed that the material can remove As and some heavy metals out of the environment, in particular: arsenic adsorption capacity (169.65 mg/kg) and some metals such as Mn, Fe, Cu, Pb, Cd, respectively: 6616.05, 6664.24, 426.07, 143.06 and 120.21 mg/kg and maintained for a period of 4 days. This shows good potential applications of sand and iron powder Fe<sup>(0)</sup> in the treatment of heavy metal pollution by column adsorption method.",
Arsenic,1030741,"Arsenic testing field kits: Some considerations and recommendations Abstract: In recent years field test kits have been largely used to identify arsenic (As) levels in contaminated water sources in Bangladesh, West Bengal (India), and elsewhere in the world to establish whether or not the water is safe. Most of the kits are based on the reaction of arsine gas with some chemical agent to form a coloured complex; the intensity of the colour is compared visually with a colour-coded chart or measured electronically to calculate the concentration of As in the water sample. In this paper, a step-wise review is presented of the analytical process used in the most commonly available As field test kits and the associated shortcomings of each of these kits. We also identify the research gaps for future work to enhance the accuracy and reliability of test results produced by these kits.",
Arsenic,1597315,"p32 protein levels are integral to mitochondrial and endoplasmic reticulum morphology, cell metabolism and survival Abstract: p32 (HAPB1, gC1qR or C1qbp) has been previously shown to have both mitochondrial and non-mitochondrial localization and functions. We show here for the first time that endogenous p32 protein is a mitochondrial protein in HeLa cells under control and stress conditions. In defining the impact of altering p32 levels in these cells, we demonstrate that the overexpression of p32 increased mitochondrial fibrils. Conversely, siRNA-mediated p32 knockdown enhanced mitochondrial fragmentation accompanied by a loss of detectable levels of the mitochondrial fusion mediator proteins Mfn1 and Mfn2. More detailed ultrastructure analysis by transmission electron microscopy revealed aberrant mitochondrial structures with less and/or fragmented cristae and reduced mitochondrial matrix density as well as more punctate ER with noticeable dissociation of their ribosomes. The analysis of mitochondrial bioenergetics showed significantly reduced capacities in basal respiration and oxidative ATP turnover upon p32 depletion. Furthermore, siRNA-mediated p32 knockdown resulted in differential stress-dependent effects on cell death, with enhanced cell death observed in the presence of hyperosmotic stress or cisplatin treatment but decreased cell death in the presence of arsenite. Taken together, our studies highlight the critical contributions of the p32 protein to the morphology of mitochondria and ER under normal cellular conditions, as well as important roles of the p32 protein in cellular metabolism and various stress responses.",
Arsenic,1031759,"Enhanced glycosyltransferase activity during thermotolerance development in mammalian cells Abstract: The cellular heat shock response leads to the enhanced synthesis of a family of heat shock proteins and the development of thermotolerance. In CHO cells, however, heat shock also leads to enhanced synthesis of a 50 kD glycoprotein and elevated activity of N-acetylgalactosaminyltransferase (GalNAcT). In this study we showed increased GalNAcT activity during thermotolerance expression in all of five mammalian cell lines included in the study. However, there was no simple correlation between cellular heat sensitivity of unheated control cells and basal levels of GalNAcT activity, measured toward the same exogenous acceptor apomucin. Although GalNAcT was elevated in thermotolerant cells, GalNAcT activity itself did not exhibit thermotolerance in terms of reduced sensitivity to heat inactivation. The increase in GalNAcT activity after heating was similar in exponentially growing and plateau-phase cultures and was inhibited neither by cycloheximide nor actinomycin D. However, the inhibitors by themselves also increased GalNAcT activity in unheated control cells. Chemical inducers of thermotolerance (arsenite and diamide) increased GalNAcT activity, but the increase was modest when compared to that following hyperthermia. In addition to GalNAcT, two other glycosyltransferases with specificity for O-glycans, alpha 1,2-fucosyltransferase and alpha 2,6-sialyltransferase, also showed increased activity after hyperthermia and during thermotolerance development. Together with previously published data, these results support the hypothesis that heat-induced activation of O-glycan-specific glycosyltransferases plays a physiological role in the cellular heat shock response and in thermotolerance development.",
Arsenic,59105,"Arsenic [III] and heavy metal ions induce intrachromosomal homologous recombination in the hprt gene of V79 Chinese hamster cells Abstract: In the present study the carcinogenic metal ions Cd[II], Co[II], Cr[VI], Ni[II], and Pb[II], as well as As[III], were examined for their ability to induce intrachromosomal homologous and nonhomologous recombination in the hprt gene of two V79 Chinese hamster cell lines, SPD8 and Sp5, respectively. With the exception of Pb[II], all of these ions enhanced homologous recombination, the order of potency being Cr>Cd>As>Co>Ni. In contrast, Cr[VI] was the only ion to enhance recombination of the nonhomologous type. In order to obtain additional information on the mechanism of recombination in the SPD8 cell line, individual clones exhibiting metal-induced recombination were isolated, and the sequence of their hprt gene determined. These findings confirmed that all recombinogenic events in this cell line were of the homologous type, involving predominantly a chromatid exchange mechanism. The mechanisms underlying the recombination induced by these ions are discussed in relationship to their genotoxicity, as well as to DNA repair and replication. Induced recombination may constitute a novel mechanism for induction of neoplastic disease.",
Arsenic,710811,"Arsenic exposure and risk of spontaneous abortion, stillbirth, and infant mortality Abstract: Millions of people worldwide are drinking water with elevated arsenic concentrations. Epidemiologic studies, mainly cross-sectional in design, have suggested that arsenic in drinking water may affect pregnancy outcome and infant health. We assessed the association of arsenic exposure with adverse pregnancy outcomes and infant mortality in a prospective cohort study of pregnant women.<br /><br /> A population-based, prospective cohort study of 2924 pregnant women was carried out during 2002-2004 in Matlab, Bangladesh. Spontaneous abortion was evaluated in relation to urinary arsenic concentrations at gestational week 8. Stillbirth and infant mortality were evaluated in relation to the average of urinary arsenic concentrations measured at gestational weeks 8 and 30.<br /><br /> : The odds ratio of spontaneous abortion was 1.4 (95% confidence interval [CI] = 0.96-2.2) among women with urine arsenic concentrations in the fifth quintile (249-1253 ?g/L; median = 382 ?g/L), compared with women in the first quintile (<33 ?g/L). There was no clear evidence of increased rates of stillbirth. The rate of infant mortality increased with increasing arsenic exposure: the hazard ratio was 5.0 (95% CI = 1.4-18) in the fifth quintile of maternal urinary arsenic concentrations (268-2019 ?g/L; median = 390 ?g/L), compared with the first quintile (<38 ?g/L).<br /><br /> We found evidence of increased risk of infant mortality with increasing arsenic exposure during pregnancy, with less evidence of associations with spontaneous abortion or stillbirth risk.",
Arsenic,2064129,"Field application of in situ electrokineticrRemediation for As-, Cu-, and Pb-contaminated paddy soil Abstract: An electrokinetic technique was used to remediate As-, Cu-, and Pb-contaminated paddy soil in a real field on a pilot scale. A hexagonal electrode placement with one anode at the center and six cathodes at the vertices of the hexagon was installed in the field. After operation for 4 weeks, the average removal of Pb was 64.9 % in the top layer (0-0.4 m), 81.2 % in the middle layer (0.4-0.8 m), and 66.9 % in the bottom layer (0.8-1.2 m). The removal of As was 28.2% in the top layer, 43.2 % in the middle layer, and 24.5 % in the bottom layer. The removal of Cu was 17.7 % in the middle layer and was not observed in the other layers. The relatively high removal of Pb might come from the more labile fraction of Pb in soil compared to As and Cu. However, the circulation of anolyte using an alkaline solution to enhance removal of As failed because the electrolyte leaked between the anode and surrounding soil. Effective circulation might enhance the performance of the electrokinetic process.",
Arsenic,710969,"Interspecies differences in metabolism of arsenic by cultured primary hepatocytes Abstract: Biomethylation is the major pathway for the metabolism of inorganic arsenic (iAs) in many mammalian species, including the human. However, significant interspecies differences have been reported in the rate of in vivo metabolism of iAs and in yields of iAs metabolites found in urine. Liver is considered the primary site for the methylation of iAs and arsenic (+3 oxidation state) methyltransferase (As3mt) is the key enzyme in this pathway. Thus, the As3mt-catalyzed methylation of iAs in the liver determines in part the rate and the pattern of iAs metabolism in various species. We examined kinetics and concentration-response patterns for iAs methylation by cultured primary hepatocytes derived from human, rat, mice, dog, rabbit, and rhesus monkey. Hepatocytes were exposed to [(73)As]arsenite (iAs(III); 0.3, 0.9, 3.0, 9.0 or 30 nmol As/mg protein) for 24 h and radiolabeled metabolites were analyzed in cells and culture media. Hepatocytes from all six species methylated iAs(III) to methylarsenic (MAs) and dimethylarsenic (DMAs). Notably, dog, rat and monkey hepatocytes were considerably more efficient methylators of iAs(III) than mouse, rabbit or human hepatocytes. The low efficiency of mouse, rabbit and human hepatocytes to methylate iAs(III) was associated with inhibition of DMAs production by moderate concentrations of iAs(III) and with retention of iAs and MAs in cells. No significant correlations were found between the rate of iAs methylation and the thioredoxin reductase activity or glutathione concentration, two factors that modulate the activity of recombinant As3mt. No associations between the rates of iAs methylation and As3mt protein structures were found for the six species examined. Immunoblot analyses indicate that the superior arsenic methylation capacities of dog, rat and monkey hepatocytes examined in this study may be associated with a higher As3mt expression. However, factors other than As3mt expression may also contribute to the interspecies differences in the hepatocyte capacity to methylate iAs.",
Arsenic,1936094,"(1)H NMR-based metabolomics investigation of Daphnia magna responses to sub-lethal exposure to arsenic, copper and lithium Abstract: Metal and metalloid contamination constitutes a major concern in aquatic ecosystems. Thus it is important to find rapid and reliable indicators of metal stress to aquatic organisms. In this study, we tested the use of (1)H nuclear magnetic resonance (NMR) - based metabolomics to examine the response of Daphnia magna neonates after a 48h exposure to sub-lethal concentrations of arsenic (49?gL(-1)), copper (12.4?gL(-1)) or lithium (1150?gL(-1)). Metabolomic responses for all conditions were compared to a control using principal component analysis (PCA) and metabolites that contributed to the variation between the exposures and the control condition were identified and quantified. The PCA showed that copper and lithium exposures result in statistically significant metabolite variations from the control. Contributing to this variation was a number of amino acids such as: phenylalanine, leucine, lysine, glutamine, glycine, alanine, methionine and glutamine as well as the nucleobase uracil and osmolyte glycerophosphocholine. The similarities in metabolome changes suggest that lithium has an analogous mode of toxicity to that of copper, and may be impairing energy production and ionoregulation. The PCA also showed that arsenic exposure resulted in a metabolic shift in comparison to the control population but this change was not statistically significant. However, significant changes in specific metabolites such as alanine and lysine were observed, suggesting that energy metabolism is indeed disrupted. This research demonstrates that (1)H NMR-based metabolomics is a viable platform for discerning metabolomic changes and mode of toxicity of D. magna in response to metal stressors in the environment.",
Arsenic,1677592,"Differential DNA Methylation in Umbilical Cord Blood of Infants Exposed to Low Levels of Arsenic in Utero Abstract: BACKGROUND: There is increasing epidemiologic evidence that arsenic exposure in utero, even at low levels found throughout much of the world, is associated with adverse reproductive outcomes and may contribute to long-term health effects. Animal models, in vitro studies, and human cancer data suggest that arsenic may induce epigenetic alterations, specifically by altering patterns of DNA methylation. OBJECTIVES: This study aims to identify differences in DNA methylation in cord blood samples of infants with in utero, low-level arsenic exposure. METHODS: DNA methylation of cord-blood derived DNA from 134 infants involved in a prospective birth cohort in New Hampshire was profiled using the Illumina Infinium Methylation450K array. In utero arsenic exposure was estimated using maternal urine samples collected at 24-28 weeks gestation. We used a novel cell mixture deconvolution methodology for examining the association between inferred white blood cell mixtures in infant cord-blood and in utero arsenic exposure and also examined the association between methylation at individual CpG loci and arsenic exposure levels. RESULTS: We found an association between urinary inorganic arsenic concentration and the estimated proportion of CD8+ T-lymphocytes (1.18; 95% CI: 0.12, 2.23). Among the top 100 CpG loci with the lowest p-values based on their association with urinary arsenic levels, there was a statistically significant enrichment of these loci in CpG Islands (p = 0.009). Of those in CpG Islands (n = 44), the majority (75%) exhibited higher methylation levels in the highest exposed group compared to the lowest exposed group. There were also several CpG loci that exhibited linear dose-dependent relationship between methylation and arsenic exposure. CONCLUSIONS: Our findings suggest that in utero exposure to low levels of arsenic may affect the epigenome. Long-term follow-up is planned to determine whether the observed changes are associated with health outcomes.",
Arsenic,62133,"The effect of methylmercury, tetraethyl lead, and sodium arsenite on the humoral immune response in mice Abstract: Male mice were exposed to methylmercury, tetraethyl lead, or sodium arsenite for 3 weeks in the drinking water at three or four concentrations ranging from 0.5 to 10.0 ppm. The humoral component of the immune system was subsequently evaluated using hemagglutination, radial immunodiffusion, and the Cunningham plaque assay (both primary and secondary immune response). Each evaluation of the immune response demonstrated immunosuppressive effects at low metal concentrations. A maximum immunosuppressive effect was produced in most instances at a metal concentration less than 2.0 ppm. Metal concentrations in the liver and kidney showed that a dose-effect relationship existed at all metal exposure levels; however, the maximal immunosuppressive effect was observed in spite of increasing tissue concentrations of the metal.",
Arsenic,574713,"Mitotic arrest-associated apoptosis induced by sodium arsenite in A375 melanoma cells is BUBR1-dependent Abstract: A375 human malignant melanoma cells undergo mitotic arrest-associated apoptosis when treated with pharmacological concentrations of sodium arsenite, a chemotherapeutic for acute promyelocytic leukemia. Our previous studies indicated that decreased arsenite sensitivity correlated with reduced mitotic spindle checkpoint function and reduced expression of the checkpoint protein BUBR1. In the current study, arsenite induced securin and cyclin B stabilization, BUBR1 phosphorylation, and spindle checkpoint activation. Arsenite also increased activating cyclin dependent kinase 1 (CDK1) Thr161 phosphorylation but decreased inhibitory Tyr15 phosphorylation. Mitotic arrest resulted in apoptosis as indicated by colocalization of mitotic phospho-Histone H3 with active caspase 3. Apoptosis was associated with BCL-2 Ser70 phosphorylation. Inhibition of CDK1 with roscovitine in arsenite-treated mitotic cells inhibited spindle checkpoint maintenance as inferred from reduced BUBR1 phosphorylation, reduced cyclin B expression, and diminution of mitotic index. Roscovitine also reduced BCL-2 Ser70 phosphorylation and protected against apoptosis, suggesting mitotic arrest caused by hyperactivation of CDK1 directly or indirectly leads to BCL-2 phosphorylation and apoptosis. In addition, suppression of BUBR1 with siRNA prevented arsenite-induced mitotic arrest and apoptosis. These findings provide insight into the mechanism of arsenic's chemotherapeutic action and indicate a functional spindle checkpoint may be required for arsenic-sensitivity.",
Arsenic,1368131,"Induction of a 31,000-dalton stress protein by prostaglandins D2 and J2 in porcine aortic endothelial cells Abstract: Prostaglandin (PG) D2 and PGJ2 stimulated porcine aortic endothelial cells to synthesize a 31,000-dalton protein (termed p31) in a time- and concentration-dependent manner. The induction of p31 synthesis was specific for PGD2, PGJ2 and PGA1 among the various PGs tested. p31 was also synthesized in response to the thiol-reactive agent diethylmaleate and heavy metal sodium arsenite but not to high temperature treatment, platelet-derived growth factor, and 12-O-tetradecanoylphorbol 13-acetate. Using two-dimensional polyacrylamide gel electrophoresis, p31 induced by PGJ2 had an isoelectric point of 5.4, which overlapped exactly with that induced by by arsenite. These results taken together indicate that p31 represents one of the stress proteins whose expression is regulated primarily by thio-active compounds but not by hyperthermia. Furthermore, it was induced by PGD2 and PGJ2 in rat capillary endothelial cells, rat skin fibroblasts, and rat hepatocytes. The data obtained from this study suggest that p31 induced by PGD2 and PGJ2 may play a role in the metabolic regulation of many mammalian cells.",
Arsenic,1019286,"Effects of arsenic on blast transformation and DNA synthesis of human blood lymphocytes Abstract: Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes were biphasic: the chemicals at very low concentrations enhanced blast transformation and DNA synthesis, whereas higher concentrations inhibited the transformation and DNA synthesis. The concentrations of arsenicals at which the maximum stimulating effect was found were 1 x 10(-5) M, 1 x 10(-6) M or 2 x 10(-6) M, and 0.8 x 10(-6) M or 1 x 10(-6) M for sodium arsenite exposure of 1 h, 3 days and 6 days, respectively; for sodium arsenate, 1 x 10(-5) M, 1 x 10(-5) M, and 2 x 10(-6) M or 5 x 10(-6) M, respectively. Arsenicals must be present for the entire 6 days culture period to produce maximum stimulation of blast transformation of human lymphocytes. The longer exposure of the lymphocytes to arsenicals, the lower the concentrations of arsenicals at which the maximum stimulating effect was found. The stimulating effect of trivalent arsenic (sodium arsenite) was stronger than pentavalent arsenic (sodium arsenate).",
Arsenic,1349142,Transgenic Expression of MsHsp23 Confers Enhanced Tolerance to Abiotic Stresses in Tall Fescue Abstract: ,
Arsenic,1032471,"Cellular uptake and biotransformation of arsenic V in transformed human cell lines HeLa S(3) and Hep G(2) Abstract: The biotransformation of arsenate was studied in two human transformed cell lines (epithelial HeLa S(3) and hepatoma Hep G(2) cells) by the determination of several arsenic species both in the culture medium and in the cells. Arsenate reduction, which was observed in the two cell lines, was higher in Hep G(2) cells. Methylation appeared to be a minor pathway for HeLa cells, but was more important in the hepatoma cells.",
Arsenic,1351396,Potability of water in Asansol coalfield rural areas: Chemical and biological studies Abstract: ,
Arsenic,918174,"Arsenic-induced hepatic mitochondrial toxicity in rats and its amelioration by dietary phosphate Abstract: The present study was aimed to test the hypothesis that inorganic phosphate may reduce arsenic toxicity by decreasing its intestinal transference. Co-administration of inorganic phosphate (6.56 M) and arsenic (6.07 mM) in the intestinal loops of rats, in situ, caused significant reduction of arsenic transference. Short-term arsenic exposure (3mg/kg body weight/day for 30 days) caused liver damage evidenced by activities of liver enzymes and necroinflammatory changes. These effects of arsenic were coupled with enhanced mitochondrial swelling, inhibition of cytochrome c oxidase, Ca(2+)-ATPase, a decrease in mitochondrial calcium content, changes in indices of hepatic mitochondrial oxidative stress and iNOS expression. Arsenic also increased hepatic caspase 3 activity and DNA fragmentation. All these apoptosis-related molecular changes caused by arsenic could be alleviated by supplementation with inorganic phosphate, which likely suggests a protective role of phosphate against arsenic-induced hepatotoxic changes.",
Arsenic,2343499,"Mathematical modelling of arsenic transport, distribution and detoxification processes in yeast Abstract: Arsenic has a dual role as causative and curative agent of human disease. Therefore, there is considerable interest in elucidating arsenic toxicity and detoxification mechanisms. By an ensemble modelling approach, we identified a best parsimonious mathematical model which recapitulates and predicts intracellular arsenic dynamics for different conditions and mutants, thereby providing novel insights into arsenic toxicity and detoxification mechanisms in yeast, which could partly be confirmed experimentally by dedicated experiments. Specifically, our analyses suggest that: (i) arsenic is mainly protein-bound during short-term (acute) exposure, whereas glutathione-conjugated arsenic dominates during long-term (chronic) exposure, (ii) arsenic is not stably retained, but can leave the vacuole via an export mechanism, and (iii) Fps1 is controlled by Hog1-dependent and Hog1-independent mechanisms during arsenite stress. Our results challenge glutathione depletion as a key mechanism for arsenic toxicity and instead suggest that (iv) increased glutathione biosynthesis protects the proteome against the damaging effects of arsenic and that (v) widespread protein inactivation contributes to the toxicity of this metalloid. Our work in yeast may prove useful to elucidate similar mechanisms in higher eukaryotes and have implications for the use of arsenic in medical therapy.",
Arsenic,2088591,"Phytotoxicities of Inorganic Arsenic and Dimethylarsinic Acid to Arabidopsis thaliana and Pteris vittata Abstract: The mechanisms by which Pteris vittata (L.) hyperaccumulates arsenic (As) have not been fully elucidated. To investigate how P. vittata tolerates high concentrations of arsenite, we compared the toxicities of various As compounds to P. vittata and Arabidopsis thaliana (L.). The phytotoxicities of As species were found to be in the order of arsenite &gt; arsenate &gt; dimethylarsinic acid (DMAA) in A. thaliana, and in the order of DMAA &gt; arsenate &gt; arsenite in P. vittata. P. vittata calli displayed a weaker ability to absorb arsenite than arsenate. These results demonstrate that P. vittata possesses mechanisms of As accumulation and detoxification.",
Arsenic,627376,"Arsenic exposure in pregnant mice disrupts placental vasculogenesis and causes spontaneous abortion Abstract: Arsenic is an abundant toxicant in ground water and soil around areas with extractive industries. Human epidemiological studies have shown that arsenic exposure is linked to developmental defects and miscarriage. The placenta is known to utilize vasculogenesis to develop its circulation. The hypothesis tested here states the following: arsenic exposure causes placental dysmorphogenesis and defective placental vasculogenesis resulting in placental insufficiency and subsequent spontaneous abortion. To test this hypothesis, pregnant mice were exposed to sodium arsenite (AsIII) through drinking water from conception through weanling stages. Neonatal assessment of birth rates, pup weights, and litter sizes in arsenic exposed and control mothers revealed that AsIII-exposed mothers had only 40% the fecundity of controls. Preterm analysis at E12.5 revealed a loss of fecundity at E12.5 from either 20 ppm or greater exposures to AsIII. There was no loss of fecundity at E7.5 suggesting that spontaneous abortion occurs during placentation. Histomorphometry on E12.5 placentae from arsenic-exposed mice revealed placental dysplasia especially in the vasculature. These results suggest that arsenic toxicity is causative for mammalian spontaneous abortion by virtue of aberrant placental vasculogenesis and placental insufficiency.",
Arsenic,1355941,"Clinical significance of AIB1 expression in human breast cancer Abstract: AIB1 (amplified in breast cancer 1) is a member of the steroid receptor coactivator family and is a key factor in enhancing estrogen-dependent transcription. To evaluate the clinical significance of AIB1 in breast cancer, we performed Southern blot analysis of the AIB1 gene on 124 human breast cancer tissues. We also performed reverse transcription-polymerase chain reaction and semi-quantitative analysis of AIB1 mRNA expression on 58 of the tissues, and immunohistochemical detection of AIB1 protein on 115 of the tissues. On Southern blot analysis, the AIB1 gene was amplified in only two of the 124 breast cancer cases. On semi-quantitative analysis, the relative expression level of AIB1 normalized to that of GAPDH varied from 0.247 to 7.721 (median = 0.94), and was not correlated with any clinico-pathological factors. Although most of the breast cancer cells revealed cytoplasmic staining of AIB1, only 16% (18 in 115) showed nuclear staining of AIB1 protein. AIB1 nuclear expression was correlated with positivity for estrogen receptor alpha (P = 0.022). Those patients with tumor samples that showed nuclear staining of AIB1 tended to be successfully treated by endocrine therapy in comparison with those who did not show nuclear staining of AIB1. In conclusion, AIB1 nuclear expression was correlated with the estrogen receptor alpha status, and patients with AIB1 nuclear expression tended to be successfully treated by hormonal therapy.",
Arsenic,1349496,Arsenic(V) adsorption from aqueous solution on magnetic Fe-0.2(Co20Ni80)(0.8) alloy porous microfibers Abstract: ,
Arsenic,1347624,"Cytoplasmic accumulation of activated leukocyte cell adhesion molecule is a predictor of disease progression and reduced survival in oral cancer patients Abstract: Activated leukocyte cell adhesion molecule (ALCAM) has been proposed to function as a cell surface sensor for cell density, controlling the transition between local cell proliferation and tissue invasion in cancer progression. Herein, we determined ALCAM expression in 107 oral squamous cell carcinomas (OSCCs), 78 oral lesions (58 hyperplasias and 20 dysplasias) and 30 histologically normal oral tissues using immunohistochemistry and correlated with clinicopathological parameters. Significant increase in ALCAM immunopositivity was observed from normal oral mucosa, hyperplasia, dysplasia to OSCCs (p(trend) &lt; 0.001). Increased ALCAM expression was observed in cytoplasm of epithelial cells as early as in hyperplasia (p = 0.001, OR = 3.8). Sixty-five of 107 (61%) OSCCs showed significant overexpression of ALCAM protein in cytoplasm/membrane of tumor cells (p = 0.043; OR = 3.3) in comparison with the normal oral tissues. Among OSCCs, cytoplasmic ALCAM was associated with advanced tumor size, tumor stage and tobacco consumption. Importantly, cytoplasmic ALCAM was an independent predictor of poor prognosis of OSCCs in multivariate analysis (p = 0.012, OR = 6.2). In an attempt to understand the molecular basis of cytoplasmic localization of ALCAM, 14-3-3 zeta and 14-3-3 sigma were identified as its novel binding partners in oral cancer cells. In conclusion, increased expression of ALCAM is an early event in oral tumorigenesis; its cytoplasmic accumulation in tumor cells is a predictor of poor prognosis of OSCCs, underscoring its potential as a candidate prognostic marker for oral cancer.",
Arsenic,1326847,"Arsenite disrupts mitosis and induces apoptosis in SV40-transformed human skin fibroblasts Abstract: Chronic ingestion of arsenite-contaminated drinking water causes skin, bladder, and liver cancer. The mechanism of arsenite-induced carcinogenesis is unknown. Arsenite is known to disrupt mitosis and to delay transit through M phase in normal diploid fibroblasts. SV40-transformed human fibroblasts were observed to be hypersensitive to the cytotoxic and cytostatic effects of NaAsO(2) compared with normal diploid fibroblasts in concentration-response experiments. Five to 20 microM NaAsO(2) induced cytostasis in cycling normal diploid fibroblasts but not overt lethality in quiescent normal diploid fibroblasts. High concentrations of arsenite were overtly lethal in both cycling and quiescent cells. The IC50 for cycling SV40-transformed fibroblasts was 3.8 and 4.8 microM for the SV40-transformed lines GM4429 and GM0637, respectively, whereas, in cycling normal diploid fibroblasts (GM0024), the IC50 was 24.7 microM. Microscopic examination of NaAsO(2)-treated SV40-transformed fibroblasts suggested a concentration-dependent accumulation of cells in mitosis undergoing apoptosis. Treatment of SV40-transformed fibroblasts with 0-10 microM NaAsO(2) caused a concentration-dependent inhibition of cell proliferation, accumulation of cells having G2/M DNA contents, and increases in the mitotic index. Phase microscopy, annexin V binding, and electron microscopy demonstrated that arrested mitotic cells underwent apoptosis. These results indicate that SV40-transformation sensitizes cells to arsenite-induced mitotic arrest and induction of apoptosis in the mitotic cells.",
Arsenic,1024696,"Effect of arsenic on the onset of menarcheal age Abstract: Ground water arsenic contamination is a major problem in the Bengal Delta plain. The present study investigates the effect of arsenic exposure on age at menarche in North 24-Parganas district, one of the worst affected districts. A higher mean menarcheal age of 12.50 years is reported from women residing in four arsenic affected villages in as compared to a control village (11.71 years). The differences in menarcheal age between three of the four affected villages and the control village are statistically significant (p &lt; 0.05). The study indicates that arsenic exposure can have a negative effect on menarcheal age.",
Arsenic,2347649,"Arsenite induces neurotoxic effects on AFD neurons via oxidative stress in Caenorhabditis elegans Abstract: Arsenic permeates our environment. As a result, humans are continually exposed to it. This study investigates the possible roles of oxidative stress in arsenite (As(iii))-induced neurotoxicity in Caenorhabditis elegans. Exposure to As(iii), at the concentrations examined, caused a decrease in locomotor behaviors (frequencies of body bends, head thrashes, and reversals) of C. elegans. In addition, As(iii) exposure (100 ?M) decreased thermotactic behaviors, and induced severe deficits in the structural properties of AFD sensory neurons. Exposure to As(iii) (100 ?M) also caused an elevated production of intracellular reactive oxygen species (ROS) in wild-type C. elegans. Pretreatment with the antioxidant curcumin ameliorated the decrease in locomotor and thermotactic behavior, the formation of deficits in the structural properties of AFD sensory neurons, and intracellular ROS in As(iii)-exposed nematodes. Our study suggests that oxidative stress plays a crucial role in the As(iii)-induced neurotoxic effects on locomotor behavior and the structures and function of AFD sensory neurons in As(iii)-exposed nematodes.",
Arsenic,627406,"Opposing effects of arsenic trioxide on hepatocellular carcinomas in mice Abstract: Arsenic trioxide (A~O.) is a potent antitumor agent used to treat acute promyelocytic leukemia (APL) and, more recently, solid tumors. However, the dose of A~O. required to suppress human xenographs in mice is markedly higher than that used to treat APL in humans. Paradoxically, low doses of A~O. stimulate angiogenesis, which might be expected to promote tumor growth. Clearly, appropriate dosages of A~O. are required to treat human patients to avoid toxicity and undesirable side effects. In the present study, we investigated As,O. with respect to its toxicity and effects on tumor growth, angiogenesis and cell apoptosis using H22 hepatocellular carcinoma (HCC) cells in a mouse model of HCC. As,O. inhibited tumor growth and angiogenesis, and enhanced tumor cell apoptosis at doses greater than 1 mg/kg, but mice lost weight and failed to thrive at doses of 4 mg/kg and greater. In contrast, low doses «1 mg/kg) of As,O. promoted tumor growth, upregulated the expression of vascular endothelial growth factor and tumor angiogenesis, and had no effect on tumor cell apoptosis./n vitro studies demonstrated that AszO. inhibited the proliferation of H22 tumor cells and bovine aortic endothelial cells, and induced their apoptosis in a dose- and time-dependent fashion, suggesting that the mechanism of A~O.-mediatedinhibition of tumor growth is due to direct effects of the drug on both tumor cells and endothelia. In summary, different doses of As,O. have opposing effects on tumor growth and angiogenesis. The results demonstrate that As,O. has a narrow window of therapeutic opportunity with respect to dosage, and that low doses of the drug as used in metronomic therapy should be used with extreme caution. (Liu, BP, S. Dong, X. Qiao, H. Jiang, H. Krissansen, G. W. Sun, X., 2006 ",
Arsenic,627836,"Arsenic-induced enhancement of ultraviolet radiation carcinogenesis in mouse skin: A dose-response study Abstract: The present study was designed to establish the form of the dose-response relationship for dietary sodium arsenite as a co-carcinogen with ultraviolet radiation (UVR) in a mouse skin model. Hairless mice (strain Skh1) were fed sodium arsenite continuously in drinking water starting at 21 days of age at concentrations of 0.0, 1.25, 2.5, 5.0, and 10 mg/L. At 42 days of age, solar spectrum UVR exposures were applied three times weekly to the dorsal skin at 1.0 kJ/m2 per exposure until the experiment ended at 182 days. Untreated mice and mice fed only arsenite developed no tumors. In the remaining groups a total of 322 locally invasive squamous carcinomas occurred. The carcinoma yield in mice exposed only to UVR was 2.4 ± 0.5 cancers/mouse at 182 days. Dietary arsenite markedly enhanced the UVR-induced cancer yield in a pattern consistent with linearity up to a peak of 11.1 ± 1.0 cancers/mouse at 5.0 mg/L arsenite, representing a peak enhancement ratio of 4.63 ± 1.05. A decline occurred to 6.8 ± 0.8 cancers/mouse at 10.0 mg/L arsenite. New cancer rates exhibited a consistent-with-linear dependence on time beginning after initial cancer-free intervals ranging between 88 and 95 days. Epidermal hyperplasia was elevated by arsenite alone and UVR alone and was greater than additive for the combined exposures as were growth rates of the cancers. These results demonstrate the usefulness of a new animal model for studying the carcinogenic action of dietary arsenite on skin exposed to UVR and should contribute to understanding how to make use of animal data for assessment of human cancer risks in tissues exposed to mixtures of carcinogens and cancer-enhancing agents.",
Arsenic,2149116,"Clinical relevance of the de novo production of anti-HLA antibodies following intestinal and multivisceral transplantation Abstract: Despite a negative pre-transplant crossmatch, intestinal transplant recipients can mount humoral immune responses soon after transplantation. Moreover, the development of donor-specific anti-HLA antibodies (DSAs) is associated with severe graft injury. Between June 2000 and August 2011, 30 patients (median age 37.6±9.8 years) received isolated intestinal transplantations (ITX, n=18) or multivisceral transplantations (MVTXs, n=12) at our center. We screened for human leukocyte antigen (HLA) antibodies pre- and post-transplant. If patients produced DSAs, treatment with plasmapheresis and intravenous immunoglobulin (IVIG) was initiated. In the event of DSA persistence and/or treatment-refractory rejection, rituximab and/or bortezomib were added. Ten patients developed DSAs and simultaneously showed significant signs of rejection. These patients received plasmapheresis and IVIG. Eight patients additionally received rituximab, and 2 patients were treated with bortezomib. DSA values decreased upon antirejection therapy in 8 of the 10 patients. The development of DSAs following ITX is often associated with acute rejection. We observed that the number of mismatched antigens and epitopes correlates with the probability of developing de novo DSAs. Early diagnosis and therapy, including B cell depletion and plasma cell inhibition, are crucial to preventing further graft injury.",
Arsenic,1597329,"MiADMSA Protects Arsenic-Induced Oxidative Stress in Human Keratinocyte 'HaCaT' Cells Abstract: Arsenic toxicity may lead to skin manifestations and arsenic accumulation in keratinised tissue. Thus human keratinocytes has been extensively used to study dermal effects of arsenic exposure. The present study was aimed to investigate time and dose-dependent effects of arsenic using HaCaT cell line. Another major focus of the study was to evaluate if treatment with monoisoamyl dimercaptosuccinic acid (MiADMSA) offers protection against arsenic-induced oxidative stress and apoptotic cell death using HaCaT cells. HaCaT cell lines were incubated to three different concentrations of arsenic (10, 30 and 50 ?M) for 24 h to identify the toxic dose by measuring oxidative stress variables. Later, MiADMSA pre-incubation for an hour preceded arsenic exposure (30 ?M). We evaluated cell morphology, lactate dehydrogenase, glutathione linked enzyme and antioxidant enzyme activities to measure oxidative stress status, while MTT assay and caspase 9 and 3 levels were determined for cell viability and apoptotic status. The present study suggests arsenic-induced toxicity in a concentration-dependant manner. Arsenic also caused a significant increase in lactate dehydrogenase accompanied by an elevated antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase and caspase activity). Interestingly, pre-treatment of cell with MiADMSA elicited significant protection against arsenic-induced oxidative stress and apoptotic cell death. The present findings are of clinical relevance and suggest MiADMSA to be a promising candidate in protecting skin against arsenic-induced toxic effects, which need further exploration using in vivo experimental models.",
Arsenic,1070485,"Increased serum level of epidermal growth factor receptor in liver cancer patients and its association with exposure to arsenic Abstract: Arsenic is a human carcinogen and can activate epidermal growth factor receptor (EGFR) in human cell lines. As EGFR is associated with the occurrence of cancers, we conducted a study to evaluate whether serum EGFR may increase in liver cancer patients, particularly in those with exposure to arsenic. We recruited 100 patients of liver cancer and 100 age- and sex-matched controls in Taiwan and determined EGFR levels in sera by enzyme-linked immunosorbent assay. The patients had higher EGFR levels (668.1 vs. 243.1fmol/mL, p&lt;0.01), and after adjusting for hepatitis B and C, they still had an average EGFR level 406.1fmol/mL higher than that of the controls (p&lt;0.01). When we compared 22 patients residing in an endemic area of arsenic intoxication to 22 age- and sex-matched patients residing outside the area, we found that patients from the endemic area had higher EGFR levels (882.8 vs. 511.6fmol/mL, p=0.04). We concluded that EGFR is over-expressed in patients of liver cancer, particularly in those with exposure to arsenic, and therefore, serum EGFR level is not only a potential biomarker of liver cancer, but also a potential biomarker of cancers associated with arsenic exposure.",
Arsenic,627235,"The enigma of arsenic carcinogenesis: role of metabolism Abstract: Inorganic arsenic is considered a high-priority hazard, particularly because of its potential to be a human carcinogen. In exposed human populations, arsenic is associated with tumors of the lung, skin, bladder, and liver. While it is known to be a human carcinogen, carcinogenesis in laboratory animals by this metalloid has never been convincingly demonstrated. Therefore, no animal models exist for studying molecular mechanisms of arsenic carcinogenesis. The apparent human sensitivity, combined with our incomplete understanding about mechanisms of carcinogenic action, create important public health concerns and challenges in risk assessment, which could be met by understanding the role of metabolism in arsenic toxicity and carcinogenesis. This symposium summary covers three critical major areas involving arsenic metabolism: its biodiversity, the role of arsenic metabolism in molecular mechanisms of carcinogenesis, and the impact of arsenic metabolism on human risk assessment. In mammals, arsenic is metabolized to mono- and dimethylated species by methyltransferase enzymes in reactions that require S-adenosyl-methionine (SAM) as the methyl donating cofactor. A remarkable species diversity in arsenic methyltransferase activity may account for the wide variability in sensitivity of humans and animals to arsenic toxicity. Arsenic interferes with DNA methyltransferases, resulting in inactivation of tumor suppressor genes through DNA hypermethylation. Other studies suggest that arsenic-induced malignant transformation is linked to DNA hypomethylation subsequent to depletion of SAM, which results in aberrant gene activation, including oncogenes. Urinary profiles of arsenic metabolites may be a valuable tool for assessing human susceptibility to arsenic carcinogenesis. While controversial, the idea that unique arsenic metabolic properties may explain the apparent non-linear threshold response for arsenic carcinogenesis in humans. In order to address these outstanding issues, further efforts are required to identify an appropriate animal model to elucidate carcinogenic mechanisms of action, and to define dose-response relationships.",
Arsenic,1381663,"Impact of in vitro gallium arsenide exposure on macrophages Abstract: The semiconductor gallium arsenide (GaAs) is classified as an immunotoxicant and a carcinogen. We previously showed that GaAs in vivo induces several phenotypic changes in macrophages located at the exposure site, indicative of an activated state. These physiological alterations may be a primary or secondary consequence of chemical exposure. To discern primary influences, our current study examined the in vitro effects of the chemical on macrophage cell lines and murine peritoneal macrophages. GaAs augmented cathepsins L and B proteolytic activities in all three sources of macrophages. Expression of the two mature isoforms of invariant chain and its cleavage fragment was also significantly increased, indicating that the chemical directly affects macrophages. However, GaAs did not alter the overall cell surface expression of major histocompatibility complex class II molecules on macrophages nor influence their ability to stimulate antigen-specific helper T cell hybridomas to respond to intact antigens that require processing. These findings raise the possibility that the chemical's complete in vivo impact may involve cytokines. Further, GaAs in vitro enhanced steady-state cathepsin L protein, and cathepsins L and B mRNA expression in macrophages, indicating that GaAs may alter gene expression, which may contribute to the chemical's adverse biological effects.",
Arsenic,1704080,"Arsenic in solution, colloidal and particulate phases of East-Hainan estuaries Abstract: During two nominal dry seasons (December 2006, March 2009) and two wet seasons (July 2007, July/August 2008) the estuarine distribution and size speciation of arsenic was studied in the Wanquan river and the Wenchang/Wenjiao river estuaries, located in tropical East-Hainan (China). Arsenic in solution and in colloidal fractions was analyzed by anodic stripping voltammetry after oxidative UV digestion thereby including inorganic As(III) and As(V) as well as organic As forms. Particulate As was determined by high-resolution ICP-MS after a microwave assisted total decomposition protocol. Taking the two relatively similar estuaries and the two expeditions for each season together, the average concentrations of total dissolved As (<0.4 mu m; td-As) of the freshwater endmember were 4.4 nM and 7.6 nM during the dry and the wet seasons, respectively, which suggests a low - if ever - level of contamination. With one exception (uptake by phytoplankton in the lower estuary), during the dry season td-As increased essentially conservatively along the salinity gradient to 14.4 nM as the mean value for salinities of about S=30. During the wet seasons, however, td-As only showed a tendency for a conservative increase; scatter in the data was attributed primarily to heavy rain and side inputs of variable As concentrations from overflowing aquaculture ponds and piles of excavated soil. The separation of colloidal fractions revealed that on average 82% of td-As remains in solution (<5 kDa), followed by 13% in small colloids (5 kDa to 30 kDa) and 5% in large colloids (30 kDa-0.4 mu m). Particulate As (0.24 +/- 0.06 mu mol/g) showed no dependence on either salinity, suspended particles, estuary or season. Relatively high distribution coefficients (logK(D)=4.48-4.81 in the freshwater; logK(D)similar to 4.18 at high salinities) arose primarily from the very low td-As. Except for certain impacts from aquaculture ponds, the two estuaries might be considered uncontaminated with respect to As.",
Arsenic,1704104,"The effect of soil bioaugmentation with strains of pseudomonas on Cd, Zn and Cu uptake by Sinapis alba L Abstract: The aim of this study was to assess the ability of selected metal resistant strains of the Pseudomonas genus to increase Zn, Cd and Cu uptake by the metalophyte Sinapis alba L. under laboratory conditions. Moreover, the mechanisms of the plant growth promotion in the tested strains and their impact on the shoots and roots of white mustard biomass were examined. Soil inoculation with the tested strains resulted in higher concentrations of Zn, Cd and Cu in the shoots and roots of the plants in comparison with those grown in non-inoculated soil. The highest phytoextraction enhancement was caused by Pseudomonas fluorescens MH15 which increased Zn, Cd and Cu accumulation in shoot tissue by 60%, 96% and 31%, respectively, in comparison with control plants. Moreover, all the tested strains also exhibited a significant increase of Cd translocation from roots to shoots of the white mustard. Three Pseudomonas putida (MH3, MH6, MH7) and two P. fluorescens biotype G and C (MH9 and MH15, respectively) strains had the ability to produce siderophore, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid as well as hydrocyanic acid. Additionally, P. putida strains were also capable of solubilizing inorganic phosphate. The ability of the tested strains to increase the metal uptake in white mustard and their plant growth-promoting properties make them good candidates for supporting heavy metal phytoextraction as well as for plant growth promoting.",
Arsenic,1453786,A combined proteomic and genetic analysis of the highly variable platelet proteome: From plasmatic proteins and SNPs Abstract: ,
Arsenic,2334159,"Oxidative DNA damage and inflammatory responses in cultured human cells and in humans exposed to traffic-related particles Abstract: Particulate pollution is a major public health concern because epidemiological studies have demonstrated that exposure to particles is associated with respiratory diseases and lung cancer. Diesel exhaust particles (DEP), which is classified as a human carcinogen (IARC, 2012), are considered a major contributor to traffic-related particulate matter (PM) in urban areas. DEP consists of various compounds, including PAHs and metals which are the principal components that contribute to the toxicity of PM. The present study aimed to investigate effects of PM on induction of oxidative DNA damage and inflammation by using lymphocytes in vitro and in human exposed to PM in the environment. Human lymphoblasts (RPMI 1788) were treated with DEP (SRM 2975) at various concentrations (25-100 ?g/ml) to compare the extent of responses with alveolar epithelial cells (A549). ROS generation was determined in each cell cycle phase of DEP-treated cells in order to investigate the influence of the cell cycle stage on induction of oxidative stress. The oxidative DNA damage was determined by measurement of 8-hydroxy-deoxyguanosine (8-OHdG) whereas the inflammatory responses were determined by mRNA expression of interleukin-6 and -8 (IL-6 and IL-8), Clara cell protein (CC16), and lung surfactant protein-A (SP-A). The results showed that RPMI 1788 and A549 cells had a similar pattern of dose-dependent responses to DEP in terms of particle uptake, ROS generation with highest level found in G2/M phase, 8-OHdG formation, and induction of IL-6 and IL-8 expression. The human study was conducted in 51 healthy subjects residing in traffic-congested areas. The effects of exposure to PM2.5 and particle-bound PAHs and toxic metals on the levels of 8-OHdG in lymphocyte DNA, IL-8 expression in lymphocytes, and serum CC16 were evaluated. 8-OHdG levels correlated with the exposure levels of PM2.5 (P&lt;0.01) and PAHs (P&lt;0.05), but this was not the case with IL-8. Serum CC16 showed significantly negative correlations with B[a]P equivalent (P&lt;0.05) levels, but positive correlation with Pb (P&lt;0.05). In conclusion, a similar pattern of the dose-dependent responses to DEP in the lymphoblasts and lung cells suggests that circulating lymphocytes could be used as a surrogate for assessing PM-induced oxidative DNA damage and inflammatory responses in the lung. Human exposure to PM leads to oxidative DNA damage whereas PM-induced inflammation was not conclusive and should be further investigated.",
Arsenic,1337341,"Antioxidant activity of protein hydrolysates from whole anchovy sprat (Clupeonella engrauliformis) prepared using endogenous enzymes and commercial proteases Abstract: BACKGROUND: The antioxidant activity and chemical properties of fish protein hydrolysates (FPHs) prepared from anchovy sprat (Clupeonella engrauliformis) using endogenous enzymes (autolysis) and commercial proteases were investigated. RESULTS: The highest degree of hydrolysis (DH) was observed with Alcalase® and papain and the highest protein recovery (PR) with Alcalase® and bromelain. FPH yield was highest with Alcalase® (82.3%) and lowest with autolysis (63.64%). Increased DH resulted in increased FPH yield (R(2) = 0.77). The highest oil recovery was observed with bromelain (6.41%) and the lowest with autolysis (3.58%). Antioxidant activity determined by DPPH, reducing power and ferrous chelation assays was highest in bromelain, Promod® and papain FPHs respectively. The highest ABTS activity was observed in Alcalase® FPH, followed by Promod® and Protamex™ FPHs. The lowest antioxidant activity was observed in autolysed and Flavourzyme® FPHs (P &gt; 0.05). Heavy metals (arsenic, lead and mercury) were recorded at levels below the regulatory limits established by the FDA. CONCLUSION: Anchovy sprat hydrolysates showed high antioxidant activities and amino acid contents and low heavy metal concentrations, indicating that they have high potential for use in human and animal diets. The high antioxidant activities are related to the high levels of hydrophobic amino acids found in this study.© 2012 Society of Chemical Industry.",
Arsenic,1337354,"Simultaneous reduction of Cr(VI) and oxidation of As(III) by Bacillus firmus TE7 isolated from tannery effluent Abstract: Hexavalent chromium [Cr(VI)] and arsenite [As(III)] are the most toxic forms of chromium and arsenic respectively, and reduction of Cr(VI) to Cr(III) and oxidation of As(III) to As(V) has great environmental implications as they affect toxicity and mobility of these toxic species. Bacillus firmus strain TE7, resistant to chromium and arsenic was isolated from tannery effluent. The strain exhibited ability to reduce Cr(VI) and oxidize As(III). It reduced 100mgL(-1) Cr(VI) within 60h in nutrient broth and oxidized 150mgL(-1) As(III) within 10h in minimal medium. It also completely reduced 15mgL(-1) Cr(VI) and oxidized 50mgL(-1) of As(III) simultaneously in minimal medium. To the best of our knowledge, this is the first bacterial strain showing simultaneous reduction of Cr(VI) and oxidation of As(III) and is a potential candidate for bioremediation of environments contaminated with these toxic metal species.",
Arsenic,1453812,"Hearing loss and heavy metal toxicity in a Nicaraguan mining community: Audiological results and case reports Abstract: We measured fingernail metal levels, Békésy-type pure-tone thresholds and distortion product otoacoustic emission (DPOAE) levels in 59 subjects residing in the gold mining community of Bonanza, Nicaragua. Auditory testing revealed widespread hearing loss in the cohort. Nail metal concentrations (mercury, lead, aluminum, manganese and arsenic) far exceeded reference levels. No relationship was found between metal levels and auditory test results for the group as a whole. Statistically significant relationships were found between DPOAE response amplitudes and metal concentrations in a subgroup with less than 40 h per week of significant noise exposure; however, conclusions regarding these relationships should be tempered by the large number of analyses performed. Several young individuals with high metal levels reported neurological symptoms and had poor hearing. The data suggest that metal levels in artisanal mining communities present a significant public health problem and may affect hearing.",
Arsenic,2088315,"Reactivity of Bridged Pentelidene Complexes with Isonitriles: A New Way to Pentel-Containing Heterocycles Abstract: The reaction of [Cp*E{W(CO)5 }2 ] (E=P (1?a), As (1?b); Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) with isonitriles RNC (R=tBu, cyclohexyl (Cy), nBu) depends on the steric demand of the substituent at the isonitrile as well as on the stoichiometry of the starting materials. With tBuNC only the Lewis acid/base adducts [Cp*E{W(CO)5 }2 (CNtBu)] (E=P (2?a), As (2?b)) are formed. The use of Cy and n-butylisonitrile leads first to the formation of the Lewis acid/base adduct, but only at low temperatures. At ambient temperatures, a rearrangement occurs and bicyclo[3.2.0]heptane derivatives of the type [{C(Me)C(CH2 )C(Me)C(Me)C(Me)}C(NR)- E{W(CO)5 }2 ] (E=P, As; R=Cy, nBu) (3?a-Cy, 3?b-Cy, 3?a-nBu and 3?b-nBu) are obtained. The use of a further equivalent of isonitrile results in products revealing two new structural motifs, the four-membered ring derivatives [C(Cp*)N(R)C(NR)E{W(CO)5 }2 ] (4: E=P, As; R=Cy, nBu) and the bicyclic complexes [[{C(Me)C- (CH2 )C(Me)C(Me)C(Me)}C(NR)2 - E{W(CO)5 }2 ] (5: E=As; R=Cy). The reaction pathway depends on the substituent at the isonitrile. By treatment of 1?a with two equivalents of CyNC only a 2H-1,3-azaphosphet complex 4?a-Cy (E=P; R=Cy) is formed. Treatment of 1?b with two equivalents of CyNC exclusively leads to the complex 5?b-Cy (E=As; R=Cy). Treatment of 1?a with two equivalents of nBuNC results in a mixture of complexes, the 2H-1,3-azaphosphet 4?a-nBu (E=P; R=nBu) and the bicyclic complex 5?a-nBu (E=P; R=nBu). For the arsenidene complex 1?b a mixture of the 2H-1,3-azarsete complex 4?b-nBu (E=As; R=nBu) and the bicyclic complex 5?b-nBu (E=P, As; R=Cy, nBu) is obtained. Complex 4?b-nBu is the first example of a 2H-1,3-azarsete complex. All products have been characterized by using mass spectrometry, NMR spectroscopy, and X-ray diffraction analysis.",
Arsenic,1070505,"The endoplasmic reticulum is a target organelle for trivalent dimethylarsinic acid (DMA(III))-induced cytotoxicity Abstract: The purpose of present study was to characterize the endoplasmic reticulum stress and generation of ROS in rat liver RLC-16 cells by exposing to trivalent dimethylarsinous acid (DMA(III)) and compared with that of trivalent arsenite (iAs(III)) and monomethylarsonous acid (MMA(III)). Protein kinase-like endoplasmic reticulum kinase (PERK) phosphorylation was significantly induced in cells exposed to DMA(III), while there was no change in phosphorylated PERK (P-PERK) detected in cells after exposure to iAs(III) or MMA(III). The generation of reactive oxygen species (ROS) after DMA(III) exposure was found to take place specifically in the endoplasmic reticulum (ER), while previous reports showed that ROS was generated in mitochondria following exposure to MMA(III). Meanwhile, cycloheximide (CHX) which is an inhibitor of protein biosynthesis strongly inhibited the DMA(III)-induced intracellular ROS generation in the ER and the phosphorylation of PERK, suggesting the induction of ER stress probably occurs through the inhibition of the protein folding process. Activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP) mRNA were induced by all three arsenic species, however, evidence suggested that they might be induced by different pathways in the case of iAs(III) and MMA(III). In addition, ER resident molecular chaperone glucose-regulated protein78 (GRP78) was not affected by trivalent arsenicals, while it was induced in positive control only at high concentration (Thapsigargin;Tg), suggesting the GRP78 is less sensitive to low levels of ER stress. In summary, our findings demonstrate that the endoplasmic reticulum is a target organelle for DMA(III)-induced cytotoxicity.",
Arsenic,744864,"Interaction of arsenic with Wnt/beta-catenin pathways in human colon cancer cells lines Abstract: Arsenic, a known human carcinogen, affects the proliferation pathways of a variety of different cells. However, there is limited information about the association between arsenic exposure and gastrointestinal cancers. Mutations in APC, a negative regulator of beta-catenin, with subsequent aberrant regulation of the Wnt/beta-catenin signalling pathway, are one of the major causes of colorectal cancer. The interactions and effects of arsenic on this pathway are unknown. We have examined this interaction using stably transfected colon cancer cell lines where APC expression is under experimental control. HT-29 cell variants were exposed to arsenic (as sodium arsenite) at 50 and 100 ppb for up to 7 days. The native cell line contains non-functional APC. Two transfected variant cell lines were examined: one contained a wild type APC under control of the metallothionein promoter; the second contained the same promoter but with no APC. Cell counts in non-APC expressing cells were 60% higher than those seen with APC, with arsenic exposure leading to increasing cell counts in a dose dependent manner. However, in cells expressing wild type APC, 100 ppb arsenite decreased the cell numbers. Degradation of beta-catenin, with inhibition of the Wnt signalling pathway, occurs through phosphorylation of beta-catenin. Functional APC is necessary to facilitate this degradation. We therefore also examined the levels of beta-catenin phosphorylation. In the presence of wild type APC, 100 ppb arsenic lead to a doubling of the levels of beta-catenin phosphorylation. No effect of arsenic on beta-catenin phosphorylation was seen in the absence of wild type APC. Taken together, these data suggest that the functional status of APC affects the interaction colon cancer cells with arsenic. Therefore, ingestion of arsenic may further exacerbate the effects of mutated APC in the development of colon cancer.",
Arsenic,1023477,"Evaluation of exposure to arsenic in residential soil Abstract: In response to concerns regarding arsenic in soil from a pesticide manufacturing plant, we conducted a biomonitoring study on children younger than 7 years of age, the age category of children most exposed to soil. Urine samples from 77 children (47% participation rate) were analyzed for total arsenic and arsenic species related to ingestion of inorganic arsenic. Older individuals also provided urine (n = 362) and toenail (n = 67) samples. Speciated urinary arsenic levels were similar between children (geometric mean, geometric SD, and range: 4.0, 2.2, and 0.89-17.7 microg/L, respectively) and older participants (3.8, 1.9, 0.91-19.9 microg/L) and consistent with unexposed populations. Toenail samples were &lt; 1 mg/kg. Correlations between speciated urinary arsenic and arsenic in soil (r = 0.137, p = 0.39; n = 41) or house dust (r = 0.049, p = 0.73; n = 52) were not significant for children. Similarly, questionnaire responses indicating soil exposure were not associated with increased urinary arsenic levels. Relatively low soil arsenic exposure likely precluded quantification of arsenic exposure above background.",
Arsenic,2347588,"An arsenic-specific biosensor with genetically engineered Shewanella oneidensis in a bioelectrochemical system Abstract: Genetically engineered microbial biosensors have yet to realize commercial success in environmental applications due, in part, to difficulties associated with transducing and transmitting traditional bioluminescent information. Bioelectrochemical systems (BESs) output a direct electric signal that can be incorporated into devices for remote environmental monitoring. Here, we describe a BES-based biosensor with genetically encoded specificity for a toxic metal. By placing an essential component of the metal reduction (Mtr) pathway of Shewanella oneidensis under the control of an arsenic-sensitive promoter, we have genetically engineered a strain that produces increased current in response to arsenic when inoculated into a BES. Our BES-based biosensor has a detection limit of ~40?M arsenite with a linear range up to 100?M arsenite. Because our transcriptional circuit relies on the activation of a single promoter, similar sensing systems may be developed to detect other analytes by the swap of a single genetic part.",
Arsenic,1032236,"Primary angiosarcoma of the urinary bladder Abstract: Angiosarcoma of the urinary bladder is an extremely rare neoplasm with only 5 cases having been reported in literature so far. The etiologic factors implicated in visceral angiosarcoma are exposure to thorium dioxide, arsenic, polyvinyl chloride, irradiation, chemotherapy and the presence of retained foreign body material. The histologic picture is characterised by irregular vascular channels showing anastomoses and lined by atypical endothelial cells. The prognosis of this neoplasm is uniformly poor. Herein we report a case of primary angiosarcoma of the bladder in a man who had no prior exposure to any of the etiologic factors and is disease free 8 months after treatment with partial cystectomy and adjuvant postoperative pelvic irradiation.",
Arsenic,1794749,"Arsenic mobilization in alluvial soils of Punjab, North-West India under flood irrigation practices Abstract: A laboratory investigation was carried out to examine the mechanism of arsenic (As) mobilization under flooded conditions (24 and 240 h) in 18 alluvial soils of Punjab, North–West India. Total dissolved As increased from a range of 3–16 ?g L?1 (mean 9 ?g L?1) to a range of 33–1,761 ?g L?1 (mean 392 ?g L?1) with the increase in flooding period from 24 to 240 h. The amount of As mobilization varied depending upon redox potential (pe) created by flooding conditions. After 24 h of flooded conditions, pe of soil water suspension ranged from ?1.75 to 0.77 (mean ?0.24). Increasing the flooding period to 240 h, pe of soil water suspension decreased in the range of ?4.49 to ?2.74 (mean ?3.29). Pourbaix diagram identified arsenate (HAsO4 2?) as predominant species in most of the alluvial soil–water suspensions under oxidized conditions, after 24 h of equilibration period, which ultimately transformed to arsenite (H3AsO3 0) after 240 h of anaerobic condition due to more reduced status. The solid phase identified was orpiment (As2S3). Identification of iron and manganese species in alluvial soil water suspension by Pourbaix diagram indicated decline in both soluble Fe2+ and SO4 2? concentration due to the formation of iron sulfide mineral phase after 240 h under anaerobic conditions. In these soils, decline in soluble Fe was also due to the precipitation of vivianite [Fe3(PO4)2·8H2O]. Elevated arsenic content and low pe value were measured in aquifers located in paddy growing fields comparative to aquifers of other sites. Large degree of variability in As concentrations was recorded in aquifers located at same sites. Thus, it is better to analyze each aquifer for their As content rather than to depends on the prediction on As content of neighbouring wells. The present investigation elucidates that flood irrigation practices in Punjab for growing paddy crop could induce the geochemical conditions favorable to mobilize arsenic from surface soils which could eventually elevate its content in the underlying shallow aquifers. Water abstracted from these aquifers by hand pumps or tube wells for drinking purposes could create hazards for local population due to loading with arsenic concentration above the safe limits. Thus, to avoid further contamination of shallow aquifers with arsenic, it is advisable to shift the flooded rice cultivation to other upland crops having lesser water requirement.",
Arsenic,1016397,"Spatial-temporal and cancer risk assessment of selected hazardous air pollutants in Seattle Abstract: In the Seattle Air Toxics Monitoring Pilot Program, we measured 15 hazardous air pollutants (HAPs) at 6 sites for more than a year between 2000 and 2002. Spatial-temporal variations were evaluated with random-effects models and principal component analyses. The potential health risks were further estimated based on the monitored data, with the incorporation of the bootstrapping technique for the uncertainty analysis. It is found that the temporal variability was generally higher than the spatial variability for most air toxics. The highest temporal variability was observed for tetrachloroethylene (70% temporal vs. 34% spatial variability). Nevertheless, most air toxics still exhibited significant spatial variations, even after accounting for the temporal effects. These results suggest that it would require operating multiple air toxics monitoring sites over a significant period of time with proper monitoring frequency to better evaluate population exposure to HAPs. The median values of the estimated inhalation cancer risks ranged between 4.3 × 10?? and 6.0 × 10??, with the 5th and 95th percentile levels exceeding the 1 in a million level. VOCs as a whole contributed over 80% of the risk among the HAPs measured and arsenic contributed most substantially to the overall risk associated with metals.",
Arsenic,1022944,"Decreased enzyme activity of hepatic thioredoxin reductase and glutathione reductase in rabbits by prolonged exposure to inorganic arsenate Abstract: Chronic exposure of humans to inorganic arsenic, mainly pentavalent arsenate (iAsV), results in drinking water-induced oxidative stress (Pi et al., 2002). Thioredoxin reductase (TR) and glutathione reductase (GR) are the two critical enzymes in the response to oxidative stress in vivo. In the present study we examined alterations in enzyme activities of hepatic TR and GR from prolonged exposure of male New Zealand white rabbits to iAsV. Exposure of rabbits to iAsV in drinking water (5 mg/L) for 18 weeks caused a significant suppression of hepatic TR and GR activities, of approximately 30% and 20%, respectively, below controls. In vitro experiments suggested that trivalent inorganic arsenic (iAsIII) but not pentavalent arsenicals including iAsV, monomethylarsonic acid (MMAsV), and dimethylarsinic acid (DMAsV) affected the hepatic TR activity of rabbit. So it was suggested that in the present study iAsV ingested via drinking water was metabolized to reactive trivalent arsenicals, such as iAsIII, which may play an important role in the decreased TR and GR activities from prolonged exposure to iAsV observed in vivo.",
Arsenic,1579323,"In utero exposure to environmental lead and manganese and neurodevelopment at 2 years of age Abstract: <strong>BACKGROUND AND OBJECTIVE: </strong>Manganese, lead, arsenic and mercury are common neurotoxic metals in the environment. Nonetheless, the relationship between prenatal exposure to low doses of neurotoxic metals and neurodevelopment in children is not clear. The objective of this study was to explore the relationship between in utero exposure to environmental neurotoxic metals and neurodevelopment at 2 years of age.<br /><br /><strong>METHODS: </strong>The population of this study came from the Taiwan Birth Panel Study. We included 230 pairs of non-smoking mothers without any occupational exposure and their singleton full-term children. The information about exposure during pregnancy was obtained using a structured questionnaire, and the manganese, lead, arsenic and mercury levels in umbilical cord blood samples were analyzed using inductively coupled plasma mass spectrometry. We used the Comprehensive Developmental Inventory for Infants and Toddlers (CDIIT) to evaluate the developmental status of each child at 2 years of age, and we examined the association of in utero exposure to environmental metals and neurodevelopment using linear regression models.<br /><br /><strong>RESULTS: </strong>The median concentrations of manganese, lead, arsenic and mercury in the cord blood samples in this study were 47.90µg/L (range, 17.88-106.85µg/L), 11.41µg/L (range 0.16-43.22µg/L), 4.05µg/L (range, 1.50-12.88µg/L) and 12.17µg/L (range, 1.53-64.87µg/L), respectively. After adjusting for maternal age, infant gender, environmental tobacco smoke during pregnancy and after delivery, Home Observation for Measurement of the Environment Inventory results, and arsenic and mercury levels in cord blood, we found that manganese and lead levels above the 75th percentile had a significant adverse association with the overall (?=-7.03, SE=2.65, P=0.0085), cognitive (?=-8.19, SE=3.17, P=0.0105), and language quotients (?=-6.81, SE=2.73, P=0.0133) of the CDIIT.<br /><br /><strong>CONCLUSIONS: </strong>In utero exposure to environmental manganese and lead may have an adverse association with neurodevelopment at 2 years of age, and there is an interaction effect between the manganese and lead levels in the cord blood that could aggravate the effect.",
Arsenic,627312,"Induction of the mammalian stress response gene GADD153 by oxidative stress: Role of AP-1 element Abstract: GADD153 is a CCAAT/enhancer-binding-protein-related gene that may function to control cellular growth in response to stress signals. In this study, a variety of oxidant treatments were shown to stimulate endogenous GADD153 mRNA expression and to transcriptionally activate a GADD153 promoter-reporter gene construct in transfected HeLa cells. Both commonalities and distinctions in the induction of GADD153 by H2O2 and the thiol-reactive compound arsenite were demonstrated. GADD153 mRNA induction by both H2O2 and arsenite was potentiated by GSH depletion, and completely inhibited by N-acetyl-cysteine. o-Phenanthroline and mannitol blocked GADD153 induction by H2O2, indicating that iron-generated hydroxyl radical mediates this induction. Concordantly, GSH peroxidase overexpression in WI38 cells attenuated GADD153 mRNA induction by H2O2. However, GADD153 induction by arsenite was only modestly reduced in the same cells, suggesting a lesser contribution of peroxides to gene activation by arsenite. We also demonstrated that oxidative stress participates in the induction of GADD153 by UVC (254 nm) irradiation. Finally, both promoter-deletion analysis and point mutation of the AP-1 site in an otherwise intact promoter support a significant role for AP-1 in transcriptional activation of GADD153 by UVC or oxidant treatment. Indeed, exposure of cells to oxidants or UVC stimulated binding of Fos and Jun to the GADD153 AP-1 element. Together, these results demonstrate that both free-radical generation and thiol modification can transcriptionally activate GADD153, and that AP-1 is critical to oxidative regulation of this gene. This study further supports a role for the GADD153 gene product in the cellular response to oxidant injury.",
Arsenic,710805,"Arsenic alters monocyte superoxide anion and nitric oxide production in environmentally exposed children Abstract: Arsenic (As) exposure has been associated with alterations in the immune system, studies in experimental models and adults have shown that these effects involve macrophage function; however, limited information is available on what type of effects could be induced in children. The aim of this study was to evaluate effects of As exposure, through the association of inorganic As (iAs) and its metabolites [monomethylated arsenic (MMA) and dimethylated arsenic (DMA)] with basal levels of nitric oxide (NO(-)) and superoxide anion (O(2)(-)), in peripheral blood mononuclear cells (PBMC) and monocytes, and NO(-) and O(2)(-) produced by activated monocytes. Hence, a cross-sectional study was conducted in 87 children (6-10 years old) who had been environmentally exposed to As through drinking water. Levels of urinary As species (iAs, MMA and DMA) were determined by hydride generation atomic absorption spectrometry, total As (tAs) represents the sum of iAs and its species; tAs urine levels ranged from 12.3 to 1411 microg/g creatinine. Using multiple linear regression models, iAs presented a positive and statistical association with basal NO(-) in PBMC (beta=0.0048, p=0.049) and monocytes (beta=0.0044, p=0.044), while basal O(2)(-) had a significant positive association with DMA (beta=0.0025, p=0.046). In activated monocytes, O(2)(-) showed a statistical and positive association with iAs (beta=0.0108, p=0.023), MMA (beta=0.0066, p=0.022), DMA (beta=0.0018, p=0.015), and tAs (beta=0.0013, p=0.015). We conclude that As exposure in the studied children was positively associated with basal levels of NO(-) and O(2)(-) in PBMC and monocytes, suggesting that As induces oxidative stress in circulating blood cells. Additionally, this study showed a positive association of O(2)(-) production with iAs and its metabolites in stimulated monocytes, supporting previous data that suggests that these cells, and particularly the O(2)(-) activation pathway, are relevant targets for As toxicity.",
Arsenic,1347025,"Glutathione protects cells against arsenite-induced toxicity Abstract: To understand the role of glutathione (GSH) in the protection of cells from arsenite toxicity, we studied the mechanism of apoptotic cell death in cells genetically unable to synthesize GSH (GCS-2 cells). Arsenite stimulated an increase in protein ubiquitination in GCS-2 cells while the wild-type cells were unaffected. Arsenite treatment increased lipid peroxidation and induced ubiquitination of molecular chaperone Hsp90 and impaired its ability to bind cochaperone p50(Cdc-37) and client proteins Plk-1 and Cdk-4 in GCS-2 cells. Treatment with arsenite also partially inhibited proteasome activity in GCS-2 cells. In these cells stably transfected with GFP(u) (a reporter consisting of a short degron fused to the COOH-terminus of GFP), intracellular fluorescence increased, suggesting the accumulation of GFP aggregates. GCS-2 cells underwent apoptosis accompanied by release of cytochrome c into the cytoplasm. Taken together, these data suggest that a possible mechanism of arsenite-induced apoptosis is the accumulation of ubiquitinated proteins and impairment of the protein degradative pathway. Further, protection from arsenite-induced ubiquitination is mediated by GSH and to a lesser extent by available reducing equivalents in the cells.",
Arsenic,656672,"Effects of exogenous GSH and methionine on methylation of inorganic arsenic in mice exposed to arsenite through drinking water Abstract: We hypothesized that chronic exposure to arsenic would deplete the reduced glutathione (GSH) and methionine in vivo, thereby impair the methylation capacity of inorganic arsenic (iAs) ingested. Our experiment was designed to explore the effects of exogenous GSH and methionine on arsenic methylation in mice exposed to arsenite via drinking water. Levels of iAs, monomethylarsenic acid (MMAs), and dimethylarsenic acid (DMAs) in the liver and blood were determined by the method of hydride generation coupled with atomic absorption spectrophotometry. Compared with mice exposed to arsenite alone, administration of GSH or methionine increased the secondary methylation index in the liver and primary methylation index in the blood, which resulted in the consequent increase of DMAs percent and decrease of iAs percent in the blood. Moreover, administration of GSH resulted in the increase of DMAs percent in the liver and total arsenic in the blood. Increase of total arsenic in the blood was mainly due to the increase of DMAs. Findings from the present study suggested that administration of GSH or methionine might potentiate the methylation capacity of arsenic in both liver and extrahepatic tissues, which may facilitate the excretion of arsenic and decrease arsenic related toxicities in the body.",
Arsenic,1018109,"Effect of metals on ?-actin and total protein synthesis in cultured human intestinal epithelial cells Abstract: <strong>INTRODUCTION: </strong>As an important structural protein, ?-actin is associated with anchoring of tight junctions (TJs) to the cell scaffold. Caco-2 cells, an immortal intestinal epithelial cell line, rely on ?-actin to form intact monolayers with high transepithelial electrical resistance in cell culture inserts.<br /><br /><strong>METHODS: </strong>We examined the effect of six metals on expression of ?-actin mRNA and ?-actin synthesis, on total and net production of newly synthesized proteins, on paracellular transport of TJ markers, and on cell viability in confluent monolayers. [(3)H]-glycine and [(3)H]-tyrosine were used as indicators of newly synthesized proteins in the absence or presence of increasing concentrations of arsenic, cadmium, copper, manganese, mercury and nickel. The monolayers were exposed to 24-h single exposures as well as continuous daily repeated doses of metals for 48-h and 96-h.<br /><br /><strong>RESULTS: </strong>Results suggest that decreases in newly synthesized proteins, in which ?-actin represents about 10%, correlated with 2- to 5-fold higher expression of ?-actin mRNA for the higher concentrations of metals. Interestingly, IC(50)s calculated for each chemical for 24-h acute and 48- and 96-h repeated dosing experiments, using the MTT viability assay and paracellular permeability markers, decreased newly synthesized and total proteins to 10% and 40% of control, respectively.<br /><br /><strong>DISCUSSION: </strong>Overall, the results indicate that, at equivalent concentrations, the metals affect ?-actin mRNA and newly synthesized proteins before cell viability and paracellular permeability are compromised. Consequently the results help in elucidating mechanisms of metal cytotoxicity that lead to understanding the relationship between tight junction integrity, paracellular transport, and cell viability.",
Arsenic,8240,"Further in vitro studies on the biochemistry of the inhibition of nucleic acid and protein synthesis induced by arsenic Abstract: Human lymphocytes, stimulated by PHA, and exposed to increasing Na2HAsO4 concentrations, show an identical incorporation rate for 14C thymidine and 14C-TTP into the DNA. 14C uridine is incorporated 3--4 per cent less at an As concentration of 1.0 mug/ml medium, above this however approximately 15 per cent less into the RNA as compared to 14C-UTP. In free pyrimidine bases, the incorporation of labelled triphosphates into the DNA and RNA is significantly reduced above 1 mug and 10 mug Na2HAsO4. Corresponding to its approximately uniform distribution into DNA and RNA, the incorporation rate of 14C-ATP above 10 mug Na2HAsO4/ml culture medium lies between that of 14C-UTP and 14C-TTP. The incorporation of 14C alanine and 14C leucine into cellular protein is not reduced below 10 mug Na2HAsO4/ml. The incorporation rate is 41 per cent at a concentration of 100 mug Na2HAsO4/ml medium. Compared to 14C-UTP, 14C-ATP and 14C-TTP it is increased by the factor of 1.8; 2.5 and 6.8 respectively. The inhibition of enzymes of the dark repair mechanisms and the synthesis of biopolymers together with their altered sequence and the involvement of long-lived messenger RNA serve as an explanation of the observed alterations of the lymphocyte metabolism, caused by arsenic.",
Arsenic,1034362,"Liver disease in vineyard sprayers Abstract: Liver disease with inclusions of copper was recognized among 30 rural workers with vineyard sprayer's lung. The pathological findings were varied: focal or diffuse swelling and proliferation of Kupffer cells; histiocytic and sarcoid-like granulomata; fibrosis of variable degree in the perisinusoidal, portal, and subcapsular areas, accompanied by atypical proliferation of the sinusoidal lining cells; micronodular cirrhosis; angiosarcoma of the liver; idiopathic portal hypertension. Abundant deposits of copper were revealed by histochemical techniques within hepatic and pulmonary lesions in these patients. The observations on the human and experimental material suggest an etiological relationship between exposure to copper sulfate and the lesions described. A morphological resemblance was noted between the liver disease of vineyard sprayers and the hepatic lesions reported in workers exposed to inorganic arsenic and to vinyl chloride. The identification of the inhaled foreign material within the liver lesions raises important etiological considerations.",
Arsenic,1351121,Modes of occurrence of arsenic in high-arsenic coal by extended X-ray absorption fine structure spectroscopy Abstract: ,
Arsenic,486422,"Oral administration of diphenylarsinic acid, a degradation product of chemical warfare agents, induces oxidative and nitrosative stress in cerebellar Purkinje cells Abstract: A new clinical syndrome with prominent cerebellar symptoms in patients living in Kamisu City, Ibaraki Prefecture, Japan, is described. Since the patients ingested drinking water containing diphenylarsinic acid (DPA), a stable degradation product of both diphenylcyanoarsine and diphenylchloroarsine, which were developed for use as chemical weapons and cause severe vomiting and sneezing, DPA was suspected of being responsible for the clinical syndrome. The purpose of the present study was to elucidate prominent cerebellar symptoms due to DPA. The aim of the study was to determine if single (15 mg/kg) or continuous (5 mg/kg/day for 5 weeks) oral administration of DPA to ICR-strain mice induced oxidative and/or nitrosative stress in their brain. Significantly positive staining with malondialdehyde (MDA) and 3-nitrotyrosine (3-NT) was observed in the cerebellar Purkinje cells by repeated administration (5 mg/kg/day) with DPA for 5 weeks that led to the cerebellar symptoms from a behavioral pharmacology standpoint and by single administration of DPA (15 mg/kg). Furthermore, it is possible that the production of 3-NT was not caused by peroxynitrite formation. The present results suggest the possibility that arsenic-associated novel active species may be a factor underlying the oxidative and nitrosative stress in Purkinje cells due to exposure to DPA, and that the damage may lead to the cerebellar symptoms. (C) 2007 Elsevier Inc. All rights reserved.",
Arsenic,1032068,"Human intake of arsenic and iodine from seaweed-based food supplements and health foods available in the UK Abstract: A number of seaweed-based products were analysed for total and 'reducible' arsenic and total iodine. Maximum potential intakes of the two elements were estimated using the manufacturers' recommended does. The levels of reducible arsenic found were generally low and, with one exception, ingestion of the products is unlikely to lead to the Joint Expert Committee on Food Additives (JECFA) Tolerable Daily Intake being exceeded. Iodine levels varied widely even between different samples of the same product. In a number of these cases the potential iodine intake is very high.",
Arsenic,628216,"Possible role of dimethylarsinous acid in dimethylarsinic acid-induced urothelial toxicity and regeneration in the rat Abstract: Dimethylarsinic acid (DMA(V)) is carcinogenic to the rat urinary bladder when administered at high doses in the diet or drinking water. At a dietary dose of 100 ppm (microg/g), it produces cytotoxicity within 6 h and increased proliferation (hyperplasia) by 7 days of administration. We hypothesize that formation of the reactive organic intermediate dimethylarsinous acid (DMA(III)) is involved in the induction of the cytotoxicity. To evaluate the possibility that DMA(V) administration produces urothelial toxicity and regeneration by the formation of trivalent arsenicals, 2,3-dimercaptopropane-1-sulfonic acid (DMPS, 5600 ppm), a chelator of trivalent arsenicals, was co-administered with DMA(V) (100 ppm) for 2 weeks to groups of female Fischer F344 rats. Based on light and scanning electron microscopy, and bromodeoxyuridine labeling index, DMA(V) produced cytotoxicity and regenerative hyperplasia of the urothelium which was inhibited by co-administration with DMPS. The major forms of arsenic in the 24-h urine of rats administered DMA(V) were high concentrations of DMA(V) (66.4 +/- 2.7 microM) itself and the pentavalent organic arsenical trimethylarsine oxide (TMAO) (73.2 +/- 9.5 microM). Co-administration with DMPS led to an increase in DMA(V) (507 +/- 31 microM) with a decrease in TMAO (2.8 +/- 0.4 microM) excretion. The formation of TMAO from DMA(V) mechanistically suggests formation of the intermediate trivalent metabolite, DMA(III). In a second experiment evaluating fresh void urines collected on study days 1, 71, and 175, we detected DMA(III) in the urine of DMA(V) and DMA(V) plus DMPS-treated rats at approximately micromolar concentrations. Using rat (MYP3) and human (1T1) urothelial cells, cytotoxicity for trivalent arsenicals, sodium arsenite, monomethylarsonous acid (MMA(III)), and DMA(III) was demonstrated at 0.4-4.8 microM concentrations, whereas MMA(V), DMA(V), and TMAO were cytotoxic at millimolar concentrations. The presence of DMA(III) at micromolar concentrations in the urine of rats fed 100 ppm DMA(V) suggests that DMA(III) produced in vivo may be involved in the toxic effects in the rat urinary bladder after dietary administration of DMA(V).",
Arsenic,1252458,"Direct exposure to gallium arsenide upregulates costimulatory activity of murine macrophages Abstract: Gallium arsenide (GaAs) is an intermetallic semiconductor compound used in the electronics industry. Acute exposure of animals to GaAs systemically suppresses several immune functions while paradoxically causing inflammation at the exposure site. We investigated the effect of GaAs on costimulatory activity of murine peritoneal macrophages, 5 days after ip exposure. Costimulation by macrophages was determined by activation of CD4(+) helper T cell hybridomas to secrete interleukin-2 in the presence of immobilized monoclonal anti-CD3 antibody. Both peritoneal exudate cells (PEC) and resident peritoneal cells exposed to GaAs provided greater costimulation to the T cells than vehicle control cells. Resident peritoneal cells exposed to GaAs were also more efficient than latex bead-exposed cells, indicating that phagocytosis alone did not cause the GaAs effect. Double immunofluorescence staining and flow cytometric analysis revealed that GaAs-exposed PEC had increased cell surface expression of costimulatory B7-1 and B7-2 molecules and intracellular adhesion molecule-1 (ICAM-1) compared to controls. In addition to these molecules, resident peritoneal macrophages exposed to GaAs also expressed significantly higher levels of heat-stable antigen (HSA). Monoclonal antibodies specific for these costimulatory molecules significantly inhibited T cell activation, demonstrating that the molecules on GaAs-exposed cells were functional. In contrast, GaAs did not upregulate costimulatory molecules on splenic macrophages. These findings suggest that direct GaAs exposure improves macrophage costimulatory activity, possibly by activating the cells, which may contribute to respiratory inflammation caused by inhalation of GaAs particles.",
Arsenic,628441,"Effects of arsenite on p53, p21 and cyclin D expression in normal human fibroblasts: A possible mechanism for arsenite's comutagenicity Abstract: Arsenite, the most likely environmental carcinogenic form of arsenic, is not significantly mutagenic at non-toxic concentrations, but is able to enhance the mutagenicity of other agents. Evidence suggests that this comutagenic effect of arsenite is due to inhibition of DNA repair, but no specific repair enzyme has been found to be sensitive to low (<1 microM) concentrations of arsenite. To determine whether arsenite affects signaling which might alter DNA repair, this study assesses the effect of arsenite on p53-related signal transduction pathways after ionizing radiation. Long-term (14 day) low dose (0.1 microM) arsenite caused a modest increase in p53 expression in WI38 normal human fibroblasts, while only toxic (50 microM) concentrations increased p53 levels after short-term (18 h) exposure. When cells were irradiated (6 Gy), p53 and p21 protein concentrations were increased after 4h, as expected. Both long-term, low dose and short-term, high dose exposure to arsenite greatly suppressed the radiation-induced increase in p21 abundance. In addition, long-term, low dose (but not short-term, high dose) exposure to arsenite resulted in increased expression of cyclin D1. These results show that in cells treated with arsenite, p53-dependent increase in p21 expression, normally a block to cell cycle progression after DNA damage, is deficient. At the same time, low (non-toxic) exposure to arsenite enhances positive growth signaling. We suggest that the absence of normal p53 functioning, along with increased positive growth signaling in the presence of DNA damage may result in defective DNA repair and account for the comutagenic effects of arsenite.",
Arsenic,1936186,Morphology and solubility products of calcium arsenates found in arsenic contaminated soils in an abandoned smelter Abstract: ,
Arsenic,1021585,"All-trans retinoic acid protects against arsenic-induced uterine toxicity in female Sprague-Dawley rats Abstract: <strong>BACKGROUND AND PURPOSE: </strong>Arsenic exposure frequently leads to reproductive failures by disrupting the rat uterine histology, hormonal integrity and estrogen signaling components of the rat uterus, possibly by generating reactive oxygen species. All-trans retinoic acid (ATRA) was assessed as a prospective therapeutic agent for reversing reproductive disorders.<br /><br /><strong>EXPERIMENTAL APPROACH: </strong>Rats exposed to arsenic for 28 days were allowed to either recover naturally or were treated simultaneously with ATRA for 28 days or treatment continued up to 56 days. Hematoxylin-eosin double staining was used to evaluate changes in the uterine histology. Serum gonadotropins and estradiol were assayed by ELISA. Expression of the estrogen receptor (ER?), an estrogen responsive gene vascular endothelial growth factor (VEGF), and cell cycle regulatory proteins, cyclin D1 and CDK4, was assessed by RT-PCR, immunohistochemistry and western blot analysis.<br /><br /><strong>KEY RESULTS: </strong>ATRA ameliorated sodium arsenite-induced decrease in circulating estradiol and gonadotropin levels in a dose- and time-dependent manner, along with recovery of luminal epithelial cells and endometrial glands. Concomitant up regulation of ER?, VEGF, cyclin D1, CDK4 and Ki-67 was also observed to be more prominent for ATRA-treated rats as compared to the rats that were allowed to recover naturally for 56 days.<br /><br /><strong>CONCLUSIONS AND IMPLICATIONS: </strong>Collectively, the results reveal that ATRA reverses arsenic-induced disruption of the circulating levels of gonadotropins and estradiol, and degeneration of luminal epithelial cells and endometrial glands of the rat uterus, indicating resumption of their functional status. Since structural and functional maintenance of the pubertal uterus is under the influence of estradiol, ATRA consequently up regulated the estrogen receptor and resumed cellular proliferation, possibly by an antioxidant therapeutic approach against arsenic toxicity.",
Arsenic,627005,"Study on the toxic effects induced by different arsenicals in primary cultured rat astroglia Abstract: Arsenic toxicity is a global health problem affecting millions of people. The objectives of this study were to determine if the toxic effects on primary cultured rat astroglia would be induced by different arsenicals. Based on alamarBlue assay and the single cell gel electrophoresis (SCGE, comet assay), the cell viability and DNA damage in the cells exposed to different arsenicals were evaluated. Treatment of astroglia with methylated arsenicals, that is, pentavalent monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV), resulted in no obvious changes in cell viability and DNA damage at micromolar concentrations. However, treatment of astroglia with inorganic arsenicals, that is, arsenite and arsenate, caused decreased cell viability and increased DNA damage at micromolar levels, and showing a dose-related decrease in mean alamarBlue reduced rate and a dose-related increase in mean comet length. Our study is therefore highly suggestive for a link between inorganic exposure and cellular toxicity or DNA damage. Based on the results of this study, the toxic effects induced by arsenite were stronger than those induced by arsenate.",
Arsenic,2347556,"Total and inorganic arsenic levels in some marine organisms from Izmir Bay (Eastern Aegean Sea): A risk assessment Abstract: The arsenic compounds in marine biota were evaluated from Izmir Bay (Eastern Aegean) and found that inorganic arsenic occurred as a minor fraction. No information is available on the annual variations of arsenic in important edible biota species from Izmir Bay. Fish and mussel samples were taken from different regions of Izmir Bay between 2009 and 2011 (n=854 individual specimens). The average percentages of inorganic arsenic to total arsenic for all biota samples were 3.43±3.38% with a range of 0.11-11.8%. The importance of speciation analysis for arsenic is supported by our work, because arsenic is ubiquitous in the ecosystem, and flexible toxicity of arsenic is based on chemical form. The average total As levels in Mullus barbatus were 6times higher than Diplodus annularis and Mytilus galloprovincialis. This study also revealed that spatial variation influenced the arsenic levels in the fish samples and the highest concentrations of arsenic were found in Gediz site. Our study showed that estimated daily intakes of arsenic via consumption of flesh fish and shell fish were below the BMDL0.5 values established by FAO/WHO.",
Arsenic,1385026,POLLUTION AEROSOL IN THE NORTHEAST USA NORTHEASTERN-MIDWESTERN CONTRIBUTIONS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM SULFATE ARSENIC INDIUM SELENIUM SULFUR DIOXIDE,
Arsenic,628320,"Metabolic methylation is a possible genotoxicity-enhancing process of inorganic arsenics Abstract: To elucidate if the metabolic methylation participates in the induction of inorganic arsenic-responsible genetic damage, arsenite (ARS) and its methylated metabolites, methanearsonic acid (MMAA) and dimethylarsinic acid (DMAA), were comparatively assayed for the induction of DNA damage by determining DNA repair synthesis using polymerization inhibitors such as aphidicolin (aph) and hydroxyurea (HU). When human alveolar epithelial type II (L-132) cells in culture were exposed to either one of these three arsenic compounds, DNA single-strand breaks resulting from the inhibition of repair polymerization were remarkably produced by exposure to DMAA at 5 to 100 microM, while not by that to ARS and MMAA even at 100 microM. Furthermore, a bromodeoxyuridine (BrdrU)-photolysis assay indicated that the induction of DNA repair synthesis was observed only in the case of exposure to DMAA. When L-132 cells were exposed to 100 microM MMAA in the presence of 10 mM S-adenosyl-L-methionine (SAM), which is a well-known methyl-group donor in metabolic methylation of arsenics, DNA repair synthesis was induced along with an increase in the amount of dimethylarsenic in the cells. These results indicate that metabolic methylation of inorganic arsenics to dimethylarsenics is predominantly involved in the induction of DNA damage.",
Arsenic,560770,"Arsenic trioxide (As2O3) induced calcium signals and cytotoxicity in two human cell lines: SY-5Y neuroblastoma and 293 embryonic kidney (HEK) Abstract: Arsenic trioxide (As2O3) has anticancer properties; however, its use also leads to neuro-, hepato- or nephro-toxicity, and therefore, it is important to understand the mechanism of As2O3 toxicity. We studied As2O3 influence on intracellular calcium ([Ca2+]i) homeostasis of human neuroblastoma SY-5Y and embryonic kidney cells (HEK 293).We also relate the As2O3 induced [Ca2+]i modifications with cytotoxicity. We used Ca2+ sensitive dyes (fluo-4 and rhod-2) combined with laser scanning microscopy or fluorescence activated cell sorting to measure Ca2+ changes during the application of As2O3 and we approach evaluation of cytotoxicity. As2O3 (1Â [mu]M) increased [Ca2+]i in SY-5Y and HEK 293 cells. Three forms of [Ca2+]i-elevations were found: (1) steady-state increases, (2) transient [Ca2+]i-elevations and (3) Ca2+-spikes. [Ca2+]i modifications were independent from extracellular Ca2+ but dependent on internal calcium stores. The effect was not reversible. Inositol triphosphate (IP3) and ryanodine (Ry) receptors are involved in regulation of signals induced by As2O3. 2-APB and dantrolene significantly reduced the [Ca2+]i-rise (pÂ <Â 0.001, t-test) but did not completely abolish [Ca2+]i-elevation or spiking. This indicates that other Ca2+ regulating mechanisms are involved. In cytotoxicity tests As2O3 significantly reduced cell viability in both cell types. Staining with Hoechst 33342 showed occurrence of apoptosis and DNA damage. Our data suggest that [Ca2+]i is an important messenger in As2O3 induced cell death.",
Arsenic,1339100,"The epigenetic effects of a high prenatal folate intake in male mouse fetuses exposed in utero to arsenic Abstract: Inorganic arsenic (iAs) is a complete transplacental carcinogen in mice. Previous studies have demonstrated that in utero exposure to iAs promotes cancer in adult mouse offspring, possibly acting through epigenetic mechanisms. Humans and rodents enzymatically convert iAs to its methylated metabolites. This reaction requires S-adenosylmethionine (SAM) as methyl group donor. SAM is also required for DNA methylation. Supplementation with folate, a major dietary source of methyl groups for SAM synthesis, has been shown to modify iAs metabolism and the adverse effects of iAs exposure. However, effects of gestational folate supplementation on iAs metabolism and fetal DNA methylation have never been thoroughly examined. In the present study, pregnant CD1 mice were fed control (i.e. normal folate, or 2.2 mg/kg) or high folate diet (11 mg/kg) from gestational day (GD) 5 to 18 and drank water with 0 or 85 ppm of As (as arsenite) from GD8 to 18. The exposure to iAs significantly decreased body weight of GD18 fetuses and increased both SAM and S-adenosylhomocysteine (SAH) concentrations in fetal livers. High folate intake lowered the burden of total arsenic in maternal livers but did not prevent the effects of iAs exposure on fetal weight or hepatic SAM and SAH concentrations. In fact, combined folate-iAs exposure caused further significant body weight reduction. Notably, iAs exposure alone had little effect on DNA methylation in fetal livers. In contrast, the combined folate-iAs exposure changed the CpG island methylation in 2,931 genes, including genes known to be imprinted. Most of these genes were associated with neurodevelopment, cancer, cell cycle, and signaling networks. The canonical Wnt-signaling pathway, which regulates fetal development, was among the most affected biological pathways. Taken together, our results suggest that a combined in utero exposure to iAs and a high folate intake may adversely influence DNA methylation profiles and weight of fetuses, compromising fetal development and possibly increasing the risk for early-onset of disease in offspring.",
Arsenic,8325,"Effects of pentachlorophenol and other chemical preservatives on the health of wood-treating workers in Hawaii Abstract: The morbidity and mortality of workers occupationally exposed to wood treating chemicals used in Hawaii for the years 1960 to 1981 were evaluated. The specific chemical exposures investigated were CCA (chromated copper-arsenate), TBTO (tributyl tin oxide) and PCP (pentachlorophenol). Results of detailed medical histories, laboratory and physiological tests, and physical examinations of 88 wood treaters were compared with those of 58 matched controls. The occupationally exposed cases had a significantly higher mean level of urinary PCP as compared to the controls (mean of 174 ppb vs. 35 ppb, micrograms/kg). There were no significant differences between the groups for the other urinary pesticide residues. The medical histories and physical examinations revealed no significant variations between the wood treaters and the comparison group. Review of all organ systems and laboratory data showed no clinically significant differences between exposed and nonexposed cohorts, although elevated hepatic enzymes in both groups merit further study. The results indicated no adverse health effects or increased incidence of mortality resulting from exposure to wood preservative chemicals in wood treaters who had worked in the industry for 0.33 to 26.3 years with a median of 6.5 years. Only 6 deaths were reported, 5 of cardiovascular disease, one of cause undetermined and none of cancer. Total number of deaths were less than the 8 anticipated for this age group.",
Arsenic,1597321,"Arsenic speciation and localization in horticultural produce grown in a historically impacted mining region Abstract: A field and market basket study (~1,300 samples) of locally grown fruits and vegetables from historically mined regions of South-West (SW) England (Cornwall and Devon), and as reference, a market basket study of similarly locally grown produce from the North-East (NE) of Scotland (Aberdeenshire) was conducted to determine the concentration of total and inorganic arsenic present in produce from these two geogenically different areas of the UK. On average 98.5% of the total arsenic found was present in the inorganic form. For both the market basket and field survey the highest total arsenic was present in open leaf structure produce (i.e. kale, chard, lettuce, greens and spinach) being most likely to soil/dust contamination of the open leaf structure. The concentration of total arsenic in potatoes, swedes and carrots was lower in peeled produce compared to unpeeled produce. For baked potatoes, the concentration of total arsenic in the skin was higher compared to the total arsenic concentration of the potato flesh, this difference in localization being confirmed by Laser Ablation - ICP-MS. For all above ground produce e.g. apples, peeling did not have a significant effect on the concentration of total arsenic present.",
Arsenic,8719,"Effects of arsenic on pyruvate dehydrogenase activation Abstract: Our studies illuminate a particular site of altered pyruvate utilization by liver mitochondria isolated from arsenic-fed rats. Initially, pyruvate dehydrogenase (PDH) levels were measured before and after in vitro activation. The liver homogenates were prepared from male rats given access to deionized drinking water solutions containing 0, 20, 40, and 85 ppm arsenic as sodium arsenate (As+5) for 3 and 6 weeks. After 3 weeks, the effects of arsenic at the highest dose level were pronounced on the basal activity (before activation), with inhibition up to 48% of the control values. The total PDH (after activation) was inhibited by 14, 15, and 28% of the control values at 20, 40, and 85 ppm As+5, respectively. A similar pattern of inhibition of PDH was observed at 6 weeks, although the inhibition was lower at the highest dose. This effect is probably a reflection of mitochondrial regeneration at this time and dose. The inhibition of PDH both before and after activation suggests a direct arsenic effect on pyruvate utilization which does not involve a lipoic acid moiety. Evidence is also presented which indicates an arsenic effect on the regulating kinase and/or phosphatase. The metabolic effects of impaired mitochondrial utilization by pyruvate are also discussed.",
Arsenic,1347011,METALLOTHIONEIN-II AND FERRITIN-H MESSENGER-RNA LEVELS ARE INCREASED IN ARSENITE-EXPOSED HELA-CELLS Abstract: ,
Arsenic,1340133,"Investigation of essential trace and toxic elements in biological samples (blood, serum and scalp hair) of liver cirrhotic/cancer female patients before and after mineral supplementation Abstract: <strong>BACKGROUND &amp;#38; AIMS: </strong>The aim of present study was to compare the levels of essential trace and toxic elements in biological samples (blood, serum and scalp hair) of female liver cirrhotic/cancer patients (n = 132), of two age groups (20-45 years) and (46-60 years), before and after sixty days treatment with mineral supplementation. For comparison purpose, same biological samples were also collected from healthy female subjects (n = 75) of same age groups.<br /><br /><strong>METHODS: </strong>The biological samples were oxidized by 65% HNO(3): 30% H(2)O(2) (2:1) in microwave oven. The digests of all biological samples were analyzed for arsenic (As), cadmium (Cd), selenium (Se) and zinc (Zn) by electrothermal atomic absorption spectrometry.<br /><br /><strong>RESULTS: </strong>The levels of Se and Zn were lower in liver cirrhotic/cancer patients as compared to healthy individuals (p &lt; 0.001). The patients of liver cirrhosis/cancer have two folds higher As and Cd levels in biological samples as related to age matched referents. Moreover, negative correlation was observed between essential and toxic elements.<br /><br /><strong>CONCLUSIONS: </strong>The pathogenesis of liver cirrhosis/cancer has been associated with changes in the balance of certain essential trace and toxic elements. It was observed that the status of Se and Zn in addition to some biochemical parameters was improved in biological samples of both groups of patients after sixty days treatment with mineral supplementation.",
Arsenic,1677561,"Metal interactions in mice under environmental stress Abstract: A metallomic analytical approach based on the use of size exclusion chromatography coupled to ICP-MS has been used to obtain metal profiles related to overexpression or inhibition of metal-binding biomolecules, which is connected to exposure experiment of laboratory mice Mus musculus to toxic metals, such as Cd, Hg and As. Exposure to Cd induces the formation of Cd-metallothionein in liver that reveals the protective role of this organ; however, exposure to Hg reduces the intensity of the peak associated to Cu-superoxide dismutase (Cu-SOD) while Hg-SOD peak increases, which suggests the competence of Cu and Hg for the active sites of SOD in liver that causes mercury translocation to kidney, in which the concentration of Hg as Hg-metallothionein increases drastically to be excreted by urine. It has been also observed the protective effect of selenium on mercury toxicity in blood plasma, which produces decreasing of the intensity of Se-protein in plasma with Hg exposure and correlative increases of Hg-albumin that transport mercury to kidney for excretion. Finally, arsenic exposure provokes the accumulation of small metabolites of this element, such as dimethylarsenic and monomethylarsenic for excretion. The application of the metallomic approach to liver extracts from free-living mouse Mus spretus shows the overexpression of Cu, Zn and Cd-peaks at 7 kDa (related to metal-metallothionein) in environmental contaminated sites, as well as the increase of peaks related to Cu- and Zn-SOD and Zn-albumin. However, in kidney, can be checked the presence of high concentration of arsenic small metabolites in contaminated areas, similarly to results found in exposure experiments. In addition, the application of a metabolomic approach based on direct infusion mass spectrometry to organ extracts (liver, kidney and serum) from mice (M. musculus) exposed to arsenic reveals important metabolic changes related to antioxidative activity, membrane cell damage, energy metabolism and arsenic elimination. Similar results were obtained from free-living mouse (M. spretus) from areas contaminated with arsenic. The integration of metallomics and metabolomics results provides a more comprehensive evaluation about the biological response in exposure experiments to toxic metals as well as in environmental assessment of contamination.",
Arsenic,2088420,Vitamin E levels in buccal cells of arsenicosis patients following vitamin E supplementation Abstract: ,
Arsenic,1019489,"Indoor risk factors for atopic eczema in school children from East Germany Abstract: This study aimed to investigate the relation between environmental influences such as arsenic, cadmium, lead, and mercury, as well as environmental tobacco smoke, pet keeping, and heating systems on the prevalence of atopic eczema. Therefore, a multicenter cross-sectional study of school children aged 5-14 years, including a standardized questionnaire, blood and urine analyses, and a dermatological examination, was undertaken. A cases-control approach was chosen in order to identify relevant risk factors. A total of 2200 school children (response 79.1%) of two areas (Bitterfeld, Hettstedt) polluted by industrial activities and an agricultural control region (Zerbst) of the former German Democratic Republic were examined. Atopic eczema as identified by dermatological examination and history was the outcome variable of interest. Body burden of arsenic and heavy metals and questionnaire data on environmental tobacco smoke exposure, pet keeping, and heating system were investigated as potential risk factors. The overall prevalence of atopic eczema was 2.6%, with higher prevalences in the industrial areas (2.5 and 2.9%) compared to the control area (1.6%, not significant). Bivariate analyses did not reveal statistically significant associations between atopic eczema and tobacco smoke exposure or the body burden of arsenic and heavy metals. According to multiple logistic regression analysis, atopic eczema was significantly more frequent in predisposed families and those who reported keeping guinea pigs (OR=4.37, CI 2.15-8.91), but not other pets, like dogs, cats, and hamsters. In comparison to a distant heating system, a decreased risk was observed in households with central heating system (OR=0.30, CI 0.10-0.90), whereas the presence of a gas heater with an exhaust pipe connection to the wall was associated with a significantly elevated risk for eczema (OR=8.22, CI 2.44-27.66). The heating system and exposure to certain animal allergens are related to the manifestation of atopic eczema. Further studies are needed to clarify how far a causal relationship is reflected by these findings.",
Arsenic,2278616,"Solvents mediated-synthesis of BiOI photocatalysts with tunable morphologies and their visible-light driven photocatalytic performances in removing of arsenic from water Abstract: BiOI photocatalysts with tunable morphologies from 2D laminar structure to 3D hierarchitectures have been prepared by a hydrothermal or solvothermal way using four kinds of solvents: water, ethanol, ethylene glycol and glycerol (these solvents are abbreviated as H2O, ETH, EG, and GLY hereinafter). The viscosity of the solvents plays a key role to the evolution on the morphologies and performances of BiOI samples. The BiOI synthesized in GLY exhibits excellent visible-light photocatalytic performances toward As(III), which is highly increased to that of N-TiO2. Further investigation reveals that the surface characteristics of BiOI nanosheets, the thickness of the nanosheets, and the way by which they integrate together play important roles in photocatalytic reaction process. The main active species is detected as O2(-). Considering about the practical use, the BiOI synthesized in GLY is also work under illumination of natural sunlight, and total arsenic concentration can be decreased even below 10?g/L from 1mg/L As(III) aqueous solution within 3h, which has reached the drinking water standard (0.01mg/L). Moreover, its stable performance also shows its great potential application value in the wastewater treatment.",
Arsenic,89906,"Cancer incidence for children born in a smelting community Abstract: The Ronnskar smelter in Skelleftea, Sweden, produces significant environmental pollutants, such as lead, arsenic, copper, cadmium and sulphur dioxide. The purpose of the present study was to determine whether children born to women living near the smelter during pregnancy had an increased risk of childhood cancer. The study group consisted of children born between 1961 and 1990 in the municipality of Skelleftea and parish of Holmsund. Through linkage to the Swedish Cancer Registry cancer diagnoses in the study group were obtained and compared with the expected ones based on the national incidence rates. Thirteen cases of childhood cancer were identified among children born in the vicinity of the smelter against 6.7 expected (SIR 195, 95%CI 88-300). Among distant born the observed number of cases (n = 42) was similar to that expected (n = 41.8).",
Arsenic,1342770,"The antioxidant role of a reagent, 2 ',7 '-dichlorodihydrofluorescin diacetate, detecting reactive-oxygen species and blocking the induction of heme oxygenase-1 and preventing cytotoxicity Abstract: Heme oxygenase-1 (HO-1) degrades heme into biliverdin, iron and CO. The enzyme participates in adaptive and protective responses to oxidative stress and various inflammatory stimuli, and is induced in response to reactive oxygen species (ROS). 2',7'-Dichlorodihydrofluorescin diacetate (DCFH-DA) is a common reagent used to detect ROS by the oxidation of 2',7'-dichlorodihydrofluorescin (DCFH) to fluorescent dichlorodihydrofluorescein. We previously found that rapid oxidation of DCFH occurred with heme-compounds as well as ROS [Ohashi, T. et al. (2002) FEBS Lett. 511, 21-27], and then examined the effect of DCFH-DA on the induction of HO-1 expression by arsenite, cadmium and hemin, which induce oxidative stress and cytotoxicity. We found suppression of the arsenite-, cadmium- and hemin-dependent induction of HO-1 with DCFH-DA. The suppression occurred at the transcriptional level since the promoter activity of the Maf-recognition site of the HO-1 gene decreased with the DCFH-DA treatment. DCFH abolished the phosphorylation of extracellular signal-regulated kinase, the nuclear translocation of a transcriptional activator Nrf2, and cell death. An antioxidant, N-acetylcysteine (NAC), also suppressed the induction by arsenite and cadmium, but not that by hemin, indicating that DCFH blocked a different site in the stress signal pathway from NAC. Considering that the oxidation of DCFH diminishes ROS generated by various stressors, our findings provide a potential strategy for protection of cells from toxic insults using DCFH-like molecules.",
Arsenic,1346910,"C-FOS MESSENGER-RNA LEVELS ARE INCREASED BY THE CELLULAR STRESSORS, HEAT-SHOCK AND SODIUM ARSENITE Abstract: ",
Arsenic,626941,"Methylated trivalent arsenic species are genotoxic Abstract: The reactivities of methyloxoarsine (MAsIII) and iododimethylarsine (DMAsIII), two methylated trivalent arsenicals, toward supercoiled ?X174 RFI DNA were assessed using a DNA nicking assay. The induction of DNA damage by these compounds in vitro in human peripheral lymphocytes was assessed using a single-cell gel (SCG, “comet”) assay. Both methylated trivalent arsenicals were able to nick and/or completely degrade ?X174 DNA in vitro in 2 h incubations at 37 °C (pH 7.4) depending on concentration. MAsIII was effective at nicking ?X174 DNA at 30 mM; however, at 150 ?M DMAsIII, nicking could be observed. Exposure of ?X174 DNA to sodium arsenite (iAsIII; from 1 nM up to 300 mM), sodium arsenate (from 1 ?M to 1 M), and the pentavalent arsenicals, monomethylarsonic acid (from 1 ?M to 3 M) and dimethylarsinic acid (from 0.1 to 300 mM), did not nick or degrade ?X174 DNA under these conditions. In the SCG assay in human lymphocytes, methylated trivalent arsenicals were much more potent than any other arsenicals that were tested. On the basis of the slopes of the concentration?response curve for the tail moment in the SCG assay, MAsIII and DMAsIII were 77 and 386 times more potent than iAsIII, respectively. Because methylated trivalent arsenicals were the only arsenic compounds that were observed to damage naked DNA and required no exogenously added enzymatic or chemical activation systems, they are considered here to be direct-acting forms of arsenic that are genotoxic, though they are not, necessarily, the only genotoxic species of arsenic that could exist.",
Arsenic,656937,"Implications of LINE1 methylation for bladder cancer risk in women Abstract: PURPOSE: Epigenetic alterations including changes to cellular DNA methylation levels contribute to carcinogenesis and may serve as powerful biomarkers of the disease. This investigation sought to determine whether hypomethylation at the long interspersed nuclear elements (LINE1), reflective of the level of global DNA methylation, in peripheral blood-derived DNA is associated with increased risk of bladder cancer. EXPERIMENTAL DESIGN: LINE1 methylation was measured from blood-derived DNA obtained from participants of a population-based incident case-control study of bladder cancer in New Hampshire. Bisulfite-modified DNA was pyrosequenced to determine LINE1 methylation status; a total of 285 cases and 465 controls were evaluated for methylation. RESULTS: Being in the lowest LINE1 methylation decile was associated with a 1.8-fold increased risk of bladder cancer [95% confidence interval (95% CI), 1.12-2.90] in models controlling for gender, age, and smoking, and the association was stronger in women than in men (odds ratio, 2.48; 95% CI, 1.19-5.17 in women; and odds ratio, 1.47; 95% CI, 0.79-2.74 in men). Among controls, women were more likely to have lower LINE1 methylation than men (P = 0.04), and levels of arsenic in the 90th percentile were associated with reduced LINE1 methylation (P = 0.04). CONCLUSIONS: LINE1 hypomethylation may be an important biomarker of bladder cancer risk, especially among women.",
Arsenic,2345929,"Di-(2-Ethylhexyl) phthalate exposure is negatively correlated with trait anxiety in girls but not with trait anxiety in boys or anxiety-like behavior in male mice Abstract: The authors aimed to study the effects of postnatal exposure to phthalate on anxiety-like behavior in mice and anxiety proneness in children. Male Imprinting Control Region (ICR) mice aged 4 weeks were administered 20 to 540 mg/kg of di-(2-ethylhexyl) phthalate (DEHP) or vehicle and assessed in the Open Field Test. A group of 277 children aged 8-11 years (150 males) was recruited from South Korea. A cross-sectional examination of urinary DEHP and dibutylphthalate metabolite concentrations was conducted, and the children were scored on the Trait Anxiety Inventory for Children (TAIC). DEHP metabolite concentrations in the urine were significantly and negatively correlated with TAIC scores in the female population but not in the male population. There were no significant group differences in the percentage of distance moved or time spent in the central area in male mice treated with DEHP or vehicle. Our results suggest a sex-dependent effect of DEHP on anxiety proneness in childhood.",
Arsenic,1022040,"Low-level subchronic arsenic exposure from prenatal developmental stages to adult life results in an impaired glucose homeostasis Abstract: We evaluated how low-level (3?ppm) subchronic inorganic arsenic (iAs) exposure from prenatal developmental stages until adult life affects glucose homeostasis. Biochemical parameters of glucose and lipid metabolism, pancreatic insulin and glycosylated haemoglobin were determined in 4-month-old female offspring of adult Wistar rats. Pancreatic histology was also performed. Statistical comparisons between control and iAs-treated groups were performed by unpaired two-tailed Student's t-test. Statistical significance was set at p&lt;0.05. We found that iAs treatment resulted in an impaired glucose tolerance test, suggestive of impaired glucose metabolism. This group was found to have hyperglycaemia and high levels of HOMA-IR, glycosylated haemoglobin, cholesterol and pancreatic insulin compared to control rats. However, plasma insulin, triglycerides and high-density lipoprotein cholesterol were not different from control rats. Moreover, ?-cell damage found in iAs-treated rats consisted of cells with a nucleus with dense chromatin and predominance of eosinophilic cytoplasm, as well as changes in the pancreatic vasculature. The current study provided evidence that subchronic iAs exposure at 3 ppm from prenatal developmental stages to adult life resulted in damage to pancreatic ? cells, affected insulin secretion and demonstrated altered glucose homeostasis, thus supporting a causal association between iAs exposure and diabetes.",
Arsenic,1029261,"A follow-up study on the efficacy of the homeopathic remedy Arsenicum album in volunteers living in high risk arsenic contaminated areas Abstract: In continuation of our short-term pilot studies reported earlier, results on certain toxicity biomarkers in volunteers who continued to take the potentized Arsenicum Album 200C till 2 years are presented. Out of some 130 'verum'-fed volunteers of pilot study, 96 continued to take the remedy till 6 months, 65 till 1 year and 15 among them continued till 2 years. They provided samples of their urine and blood at 6 months, 1 year and finally at 2 years. None out of 17 who received 'placebo' turned up for providing blood or urine at these longer intervals. Standard methodologies were used for determination of arsenic content in blood and urine, and for measurement of toxicity biomarkers like acid and alkaline phosphatases, alanine and aspartate amino transferases, lipid peroxidation and reduced glutathione and anti-nuclear antibody titers. Most of the volunteers reported status quo maintained after the improvement they achieved within the first 3 months of homeopathic treatment, in respect of their general health and spirit, and appetite and sleep. A few with skin symptoms and burning sensation, however, improved further. This was supported by the data of toxicity biomarkers, levels of all of which remained fairly within normal range. Therefore, administration of Arsenicum Album 200C considerably ameliorates symptoms of arsenic toxicity on a long-term basis, and can be recommended for interim use, particularly in high risk remote villages lacking modern medical and arsenic free drinking water facilities. Similar studies by others are encouraged.",
Arsenic,1020907,"Depolarization of mitochondria and activation of caspases are common features of arsenic(III)-induced apoptosis in myelogenic and lymphatic cell lines Abstract: The clinical efficacy of arsenic(III) oxide (As(2)O(3)) has been shown in patients with relapsed acute promyelocytic leukemia (APL). To identify potential common primary targets of action of As(2)O(3) in myelogenic and lymphatic cell lines, we analyzed As(2)O(3) effects on caspases and on the mitochondrial membrane potential (Psi(M)) under uniform conditions. As(2)O(3) induced breakdown of Psi(M) and activated caspases in cell lines with different sensitivities for As(2)O(3), including cell lines resistant to mitoxantron or camptothecin but sensitive to As(2)O(3). Caspase inhibitors could not prevent breakdown of Psi(M) in lymphoid cell lines, whereas activation of caspases and apoptosis could be inhibited. Activation of caspases seems to be a downstream effect occurring after breakdown of Psi(M). We could show that all of these effects are independent of MDR-1 expression. There was no difference in the mode of action of As(2)O(3) in cell lines sensitive or resistant to camptothecin, mitoxantrone, or doxorubicin. As(2)O(3) deserves further evaluation as an adjunct or alternative to other cytostatic drugs.",
Arsenic,1016864,"Arsenite pretreatment attenuates benzo[a]pyrene cytotoxicity in a human lung adenocarcinoma cell line by decreasing cyclooxygenase-2 levels Abstract: Both simultaneous and sequential exposure to arsenite and benzo[a]pyrene (BaP) potentially occur in human populations drinking arsenic-contaminated water or burning arsenic-contaminated coal. Although arsenite and BaP are both well-documented hazardous substances and human carcinogens, interactions between these two agents have not been well defined. In this study, we demonstrated that posttreatment with arsenite synergistically enhanced the cytotoxicity of BaP for a human lung adenocarcinoma cell line, CL3. In contrast, pretreatment of CL3 cells with arsenite attenuated BaP cytotoxicity. Involvement of heat-shock protein 70 and heme oxygenase-1 in this arsenite-mediated attenuation of BaP cytotoxicity was ruled out. Our data also indicated that arsenite pretreatment did not affect the BaP-mediated induction of CYP1A1, the initial enzyme involved in its metabolic activation, but did result in a significant decrease in mRNA and protein levels of cyclooxygenase-2 (COX-2), which is required to convert the BaP metabolite BaP 7,8-dihydrodiol to the ultimate epoxide. In contrast to the high susceptibility of CL3 cells to BaP, the human lung carcinoma cells, H460, and CL3R15 cells (arsenic-resistant CL3 cells) showed normal CYP1A1 inducibility by BaP, had negligible amounts of COX-2, and were highly resistant to BaP. The involvement of COX-2 in BaP activation was confirmed by transfection of H460 cells with a recombinant adenovirus, Ad-pgk-Cox2, coding for COX-2, which resulted in a significant increase in the levels of the COX-2 product prostaglandin E2 in the medium and in the susceptibility of H460 cells to BaP. The present study confirms the importance of COX-2 in BaP activation and demonstrates that the arsenite-mediated attenuation of BaP cytotoxicity is mediated by a reduction in COX-2 levels.",
Arsenic,1677603,"Metal cycling during sediment early diagenesis in a water reservoir affected by acid mine drainage Abstract: The discharge of acid mine drainage (AMD) into a reservoir may seriously affect the water quality. To investigate the metal transfer between the water and the sediment, three cores were collected from the Sancho Reservoir (Iberian Pyrite Belt, SW Spain) during different seasons: turnover event; oxic, stratified period; anoxic and under shallow perennially oxic conditions. The cores were sliced in an oxygen-free atmosphere, after which pore water was extracted by centrifugation and analyzed. A sequential extraction was then applied to the sediments to extract the water-soluble, monosulfide, low crystallinity Fe(III)-oxyhydroxide, crystalline Fe(III)-oxide, organic, pyrite and residual phases. The results showed that, despite the acidic chemistry of the water column (pH&lt;4), the reservoir accumulated a high amount of autochthonous organic matter (up to 12wt.%). Oxygen was consumed in 1mm of sediment due to organic matter and sulfide oxidation. Below the oxic layer, Fe(III) and sulfate reduction peaks developed concomitantly and the resulting Fe(II) and S(II) were removed as sulfides and probably as S linked to organic matter. During the oxic season, schwertmannite precipitated in the water column and was redissolved in the organic-rich sediment, after which iron and arsenic diffused upwards again to the water column. The flux of precipitates was found to be two orders of magnitude higher than the aqueous one, and therefore the sediment acted as a sink for As and Fe. Trace metals (Cu, Zn, Cd, Pb, Ni, Co) and Al always diffused from the reservoir water and were incorporated into the sediments as sulfides and oxyhydroxides, respectively. In spite of the fact that the benthic fluxes estimated for trace metal and Al were much higher than those reported for lake and marine sediments, they only accounted for less than 10% of their total inventory dissolved in the column water.",
Arsenic,1597412,"An in vitro method for estimation of arsenic relative bioavailability in soil Abstract: This report summarizes the results of a study to develop an in vitro bioaccessibility (IVBA) extraction technique for estimating the relative bioavailability (RBA) of arsenic (As) in soil. The study was implemented in several steps. In step 1, key variables in the extraction protocol were identified. In step 2, 21 different extraction conditions were tested on 12 different soils with reliable RBA values measured in swine or monkeys to identify which yielded useful in vivo-in vitro correlations (IVIVC). In step 3, three extraction conditions were evaluated using 39 different test soils to make a final selection of the best IVIVC. In step 4, the within- and between-lab reproducibility of the extraction method was examined. The optimum IVIVC model for swine utilized a pH 1.5 IVBA extraction fluid, with an R (2) value of .723. For monkeys, the optimum IVIVC model was obtained using a pH 7 IVBA extraction fluid that contained phosphate, with an R (2) value of .755. Within-lab precision of IVBA results was typically less than 3%, with an average of 0.8% for all 4 labs. Between-lab variation in mean IVBA values was generally less than 7%, with an overall average of 3%. The principal advantages of this IVBA method compared to other in vitro methods described in the literature are that (1) the fluids and extraction conditions are simple, (2) the results have been calibrated against a larger data set than any other method, and (3) the method has been demonstrated to be reproducible both within and between labs.",
Arsenic,2149115,"Equilibrium and kinetics studies of arsenate adsorption by FePO4 Abstract: The present work is focusing on removal of arsenate from aqueous solution using FePO4. The equilibrium study regarding the removal of arsenic by FePO4 was carried out at 298, 308, 318 and 328K. Langmuir parameters were found to increase with the increase in temperature indicating that the adsorption is favorable at high temperature. Kinetic study of arsenate adsorption on FePO4 was also carried out at different temperatures and at pH 6 and 8. Different kinetic models were used to the kinetic data amongst which pseudo second order model was best fitted. The mechanism of the adsorption kinetics was investigated by employing intraparticle diffusion and Richenberg models. The energy of activation (Ea) was found to be 30 and 35.52kJmol(-1) at pH 6 and pH 8, respectively, suggesting chemisorption nature of the adsorption process. The negative entropic values of activation signified the existence of entropy barrier while the positive ?G(#) values indicated the existence of energy barrier to be crossed over for the occurrence of a chemical reaction. Both the spectroscopic studies and increase in equilibrium pH reveal the anion exchange removal of arsenate from aqueous solution to the solid surface.",
Arsenic,1018616,"Toxic gas generation from plastic mattresses and sudden infant death syndrome Abstract: Microbial generation of toxic gases from antimony, arsenic, or phosphorus in compounds used as fire retardants in cot mattresses has been proposed as a cause of sudden infant death. To test this hypothesis, 23 polyvinyl chloride mattress samples from cot death cases were incubated on malt agar plates until good microbial growth was obtained. Silver nitrate and mercuric chloride test papers were then inserted and the colour reactions recorded. The predominant organism, recovered from all mattresses tested, was not, as claimed in earlier work, the fungus Scopulariopsis brevicaulis, but a mix of common environmental Bacillus spp. Test paper colour changes occurred whenever bacterial growth was present, but these reactions also occurred in control tests in which no mattress material was present on the plates. Chemical and instrumental analyses of exposed test papers showed that the colour reactions were not due to deposits of antimony, arsenic, or phosphorus. Our findings do not support the hypothesis that toxic gases derived from antimony, arsenic, or phosphorus are a cause of sudden infant death. More sulphur was found in test papers exposed in plates containing bacterial growth than in those without such growth. This result suggests that the test paper reactions were due to the generation of sulphur-containing compounds during bacterial growth on the agar medium.",
Arsenic,2345807,"Archaeometric characterization of 17th-century tin-glazed Anabaptist (Hutterite) faience artefacts from North-East-Hungary Abstract: The paper presents the first results of a long-term project aiming to reconstruct the production technology of the Anabaptist (Hutterite) tin-glazed ceramics produced in Eastern-Central Europe. Microanalytical investigations were performed on 17th-century faience artefacts (six samples) excavated at Sarospatak, North-East-Hungary. The results are compared with analytical data on the direct or indirect precursor, Italian maiolica. The studied Hutterite faience artefacts reveal similarities with Italian maiolica. Calcareous clay with 14-22 wt% CaO was used for the buff-coloured ceramic body. Up to about 400 mu m thick, tin-opacified white and blue lead-alkali glaze was applied on the biscuit-fired body. The glaze suspension contained sand admixture and a significant amount of common salt and was not fritted before application. The colorants used for the ceramic colours are lead antimonate for yellow, cobalt with arsenic, nickel and iron for blue, copper for green and manganese with minor iron for black. The ceramic colours were applied on the unfired glaze and maturing occurred during the second firing. The main technological difference when compared with the Italian Renaissance maiolica is the deliberate use of a high amount of tin oxide (17-20 wt% SnO2) together with 18-28 wt% PbO content for white glaze of the studied Hutterite faience.",
Arsenic,734864,"Arsenic exposure, urinary arsenic speciation, and the incidence of urothelial carcinoma: A twelve-year follow-up study Abstract: The risk of urothelial carcinoma (UC) and urinary arsenic speciation have been evaluated in a few case-control studies; however, the association has not been verified in a prospective cohort study. The aim of this study was to examine the association between urinary arsenic speciation and the incidence of UC in a cohort study. A total of 1,078 residents of southwestern Taiwan were followed for an average of 12 years. A high-performance liquid chromatography/hydride generator and an atomic absorption spectrometry were used to measure urinary arsenite, arsenate, monomethylarsonic acid (MMA(V)), and dimethylarsinic acid (DMA(V)). The incidence of UC was estimated by examining the National Cancer Registry of Taiwan between January 1985 and December 2001. There were 37 newly diagnosed cases of UC during a follow-up period of 11,655 person-years. Significantly higher percentages of MMA(V) and lower percentages of DMA(V) existed among the patients with UC than among the healthy residents. After adjustment for age, gender, educational level, and smoking status, the percentage of urinary DMA(V) was shown to have an inverse association with the risk of UC, having a relative risk (RR) of the tertile strata of 1.0, 0.3, and 0.3, respectively (p &lt; 0.05 for the trend test). The RR (95% confidence interval) of residents with a cumulative arsenic exposure (CAE) of &gt;/=20 mg/l-year and a higher percentage of MMA(V) or a CAE of &gt; or =20 mg/l-year and a lower percentage of DMA(V) was 3.7 (1.2-11.6) or 4.2 (1.3-13.4) compared to residents with a CAE of &lt;20 mg/l-year and a lower percentage of MMA(V) or a CAE of &lt;20 mg/l-year and a higher percentage of DMA(V )respectively. There was a significant association between inefficient arsenic methylation and the development of UC in the residents in the high CAE exposure strata in an area of southwestern Taiwan endemic for arseniasis.",
Arsenic,979751,"Protective effect of nitric oxide against arsenic-induced oxidative damage in tall fescue leaves Abstract: Nitric oxide (NO) is a key molecule involved in many physiology processes. The effects of NO on alleviating arsenic-induced oxidative damage in tall fescue leaves were investigated. Arsenic (25 mu M) treatment induced significantly accumulation of reactive oxygen species (ROS) and led to serious lipid peroxidation in tall fescue leaves and the alication of 100 mu M SNP before arsenic stress resulted in alleviated arsenic-induced electrolyte leakage and malondiadehyde (MDA) content in tall fescue leaves, the levels of hydrogen peroxide (H(2)O(2)) and superoxide radical (O(2)(center dot-)) were reduced as well. Moreover, the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) increased in tall fescue leaves in presence of SNP under arsenic stress. This pattern was reversed by application of NO scavenger, 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethy-limidazoline-1-oxyl-3-oxide (PTIO) before arsenic treatment. Pronounced increases in endogenous NO production was found in plants after exposure to arsenic stress. The results suggested that arsenic stress elevated endogenous NO level and that NO might act as a signaling molecule to enhance antioxidant enzyme activities, further protecting against injuries caused by arsenic toxicity.",
Arsenic,1519024,"Chronic arsenicosis in cattle: Possible mitigation with Zn and Se Abstract: Supply of arsenic free water in the arsenic endemic zone of West Bengal since a long time could not prevent arsenicosis in human completely. So exploration of arsenic contamination at all levels of food chain may be important. The report on arsenicosis in cattle of arsenic affected zone is scarcely available. In the present study, cattle from villages of two arsenic endemic blocks (Chakdah and Haringhata) in Nadia district of West Bengal were selected. The cattle affected with arsenicosis were identified and isolated. They were divided into two groups: untreated control group and treated group-was treated with mixture of zinc oxide (10mg/kg) and sodium selenite (0.1mg/kg) orally once daily for 180 days. Milk, faeces and hair samples were collected at different time intervals from those cattle for analysis of arsenic. Drinking water and straw of those areas were also collected for analysis of arsenic. Serum ALT and AST were estimated in collected blood samples of the cattle. The untreated control group had shown gradual accumulation of total arsenic in hair while the treated group showed a non-significant but declined accumulation of arsenic in hair from 90th day onwards and a significant increase (p&lt;0.05) in total arsenic in faeces from 90th day onwards. The arsenic load considerably but non-significantly decreased in milk from 60th day onwards in the treated group. Serum AST and ALT activities were also decreased in treated cattle. It is concluded that straw is also a major source of arsenic contamination in cattle apart from drinking water and arsenic may enter into human through consumption of contaminated milk. But zinc and selenium mixture may be used to reduce arsenic load in cattle.",
Arsenic,1018360,"Serum beta-carotene level, arsenic methylation capability, and incidence of skin cancer Abstract: To elucidate the associations of arsenic-induced skin cancer with serum beta-carotene level and arsenic methylation capability, a total of 654 residents of age 30 or older were recruited from three arseniasis-hyperendemic villages in Taiwan and regularly examined for skin lesions during the follow-up period. There were 33 cases affected with newly diagnosed skin cancer during the follow-up, giving an incidence of 14.74 per 1000 person-years. Although most study subjects had stopped consuming high-arsenic artesian well water more than 20 years ago, the risk of skin cancer was found to increase significantly with cumulative arsenic exposure before the cessation of drinking artesian well water in a dose-response relationship. Frozen serum samples collected at the recruitment from newly developed skin cancer cases and matched controls were tested for beta-carotene levels by high-performance liquid chromatography. Frozen urine samples of these subjects were examined by high-performance liquid chromatography to speciate arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA), and dimethylarsinic acid and then quantitated by hydride generator combined with atomic absorption spectrometry. Skin cancer cases had a significantly lower serum level of beta-carotene than matched healthy controls. Although the primary methylation capability indexed by the ratio of MMA/(AsIII + AsV) was greater in cases than in controls, the secondary methylation capability indexed by the ratio of dimethylarsinic acid/MMA was lower in cases than in controls. An elevated proportion of MMA in total urinary arsenic level was associated with an increased risk of skin cancer. Subjects with a cumulative arsenic exposure of &gt; or = 20.0 mg/liter-year and a proportion of MMA in total urinary arsenic level &gt;26.7% had a multivariate-adjusted odds ratio of developing skin cancer as high as 20.91 (95% confidence interval, 2.63-166.5) compared wih those who had a cumulative arsenic exposure of &lt;20.0 mg/liter-year and a MMA percentage of &lt; or = 26.7%. Whether the association with capability of inorganic methylation is also applied to cancers of internal organs, including lung, liver, and urinary bladder, remains to be elucidated.",
Arsenic,1339045,"Progesterone production requires activation of caspase-3 in preovulatory granulosa cells in a serum starvation model Abstract: Granulosa cells proliferate, differentiate, and undergo apoptosis throughout follicular development. Previous studies have demonstrated that stimulation of progesterone production is accompanied by caspase-3 activation. Moreover, we previously reported that arsenic enhanced caspase-3 activity coupled with progesterone production. Inhibition of caspase-3 activity can significantly inhibit progesterone production induced by arsenic or follicle-stimulating hormone (FSH). Here, we report that serum starvation induces caspase-3 activation coupled with augmentation of progesterone production. Serum starvation also increased the levels of cytochrome P450 cholesterol side chain cleavage enzyme (P450scc) and steroidogenic acute regulatory (StAR) protein, both of which may contribute to progesterone synthesis in preovulatory granulosa cells. Inhibition of caspase-3 activity resulted in a decrease in progesterone production. Deactivation of caspase-3 activity by caspase-3 specific inhibitor also resulted in decreases in P450scc and StAR expression, which may partly contribute to the observed decrease in progesterone production. Our study demonstrates for the first time that progesterone production in preovulatory granulosa cells is required for caspase-3 activation in a serum starvation model. Inhibition of caspase-3 activity can result in decreased expression of the steroidogenic proteins P450scc and StAR. Our work provides further details on the relationship between caspase-3 activation and steroidogenesis and indicates that caspase-3 plays a critical role in progesterone production by granulosa cells.",
Arsenic,1453795,"Potential role of sodium-proton exchangers in the low concentration arsenic trioxide-increased intracellular pH and cell proliferation Abstract: Arsenic main inorganic compound is arsenic trioxide (ATO) presented in solution mainly as arsenite. ATO increases intracellular pH (pHi), cell proliferation and tumor growth. Sodium-proton exchangers (NHEs) modulate the pHi, with NHE1 playing significant roles. Whether ATO-increased cell proliferation results from altered NHEs expression and activity is unknown. We hypothesize that ATO increases cell proliferation by altering pHi due to increased NHEs-like transport activity. Madin-Darby canine kidney (MDCK) cells grown in 5 mmol/L D-glucose-containing DMEM were exposed to ATO (0.05, 0.5 or 5 µmol/L, 0-48 hours) in the absence or presence of 5-N,N-hexamethylene amiloride (HMA, 5-100 µmol/L, NHEs inhibitor), PD-98059 (30 µmol/L, MAPK1/2 inhibitor), Gö6976 (10 µmol/L, PKC?, ?I and ? inhibitor), or Schering 28080 (10 µmol/L, H(+)/K(+)ATPase inhibitor) plus concanamycin (0.1 µmol/L, V type ATPases inhibitor). Incorporation of [(3)H]thymidine was used to estimate cell proliferation, and counting cells with a hemocytometer to determine the cell number. The pHi was measured by fluorometry in 2,7-bicarboxyethyl-5,6-carboxyfluorescein loaded cells. The Na(+)-dependent HMA-sensitive NHEs-like mediated proton transport kinetics, NHE1 protein abundance in the total, cytoplasm and plasma membrane protein fractions, and phosphorylated and total p42/44 mitogen-activated protein kinases (p42/44(mapk)) were also determined. Lowest ATO (0.05 µmol/L, ~0.01 ppm) used in this study increased cell proliferation, pHi, NHEs-like transport and plasma membrane NHE1 protein abundance, effects blocked by HMA, PD-98059 or Gö6976. Cell-buffering capacity did not change by ATO. The results show that a low ATO concentration increases MDCK cells proliferation by NHEs (probably NHE1)-like transport dependent-increased pHi requiring p42/44(mapk) and PKC?, ?I and/or ? activity. This finding could be crucial in diseases where uncontrolled cell growth occurs, such as tumor growth, and in circumstances where ATO, likely arsenite, is available at the drinking-water at these levels.",
Arsenic,2337263,"Population Structure of Listeria monocytogenes Serotype 4b Isolates from Sporadic Human Listeriosis in the United States, 2003-2008 Abstract: Listeria monocytogenes can cause severe foodborne disease (listeriosis). Numerous outbreaks have involved three serotype 4b epidemic clones (ECs): ECI, ECII and ECIa. However, little is known about the population structure of L. monocytogenes serotype 4b from sporadic listeriosis in the United States, even though most cases of human listeriosis are in fact sporadic. Here we analyzed 136 serotype 4b isolates from sporadic cases in the United States, 2003-2008, utilizing multiple tools including multilocus genotyping, pulsed-field gel electrophoresis and sequence analysis of the inlAB locus. ECI, ECII and ECIa were frequently encountered (32, 17 and 7%, respectively). However, annually 30-68% of isolates were outside of these ECs and several novel clonal groups were identified. An estimated 33 and 17% of the isolates, mostly among the ECs, were resistant to cadmium and arsenic, respectively, but resistance to benzalkonium chloride was uncommon (3%) among the sporadic isolates. Frequency of clonal groups fluctuated within the six-year study period, without consistent trends. However, on several occasions, temporal clusters of isolates with indistinguishable genotypes were detected, suggesting the possibility of hidden multistate outbreaks. Our analysis suggests a complex population structure of serotype 4b L. monocytogenes from sporadic disease, with important contributions by ECs and several novel clonal groups. Continuous monitoring will be needed to assess long term trends in clonality patterns and population structure of L. monocytogenes from sporadic listeriosis.",
Arsenic,627095,"Breast-feeding protects against arsenic exposure in Bangladeshi infants Abstract: BACKGROUND: Chronic arsenic exposure causes a wide range of health effects, but little is known about critical windows of exposure. Arsenic readily crosses the placenta, but the few available data on postnatal exposure to arsenic via breast milk are not conclusive. AIM: Our goal was to assess the arsenic exposure through breast milk in Bangladeshi infants, living in an area with high prevalence of arsenic-rich tube-well water. METHODS: We analyzed metabolites of inorganic arsenic in breast milk and infant urine at 3 months of age and compared them with detailed information on breast-feeding practices and maternal arsenic exposure, as measured by concentrations in blood, urine, and saliva. RESULTS: Arsenic concentrations in breast-milk samples were low (median, 1 microg/kg; range, 0.25-19 microg/kg), despite high arsenic exposures via drinking water (10-1,100 microg/L in urine and 2-40 microg/L in red blood cells). Accordingly, the arsenic concentrations in urine of infants whose mothers reported exclusive breast-feeding were low (median, 1.1 microg/L; range, 0.3-29 microg/L), whereas concentrations for those whose mothers reported partial breast-feeding ranged from 0.4 to 1,520 microg/L (median 1.9 microg/L). The major part of arsenic in milk was inorganic. Still, the infants had a high fraction (median, 87%) of the dimethylated arsenic metabolite in urine. Arsenic in breast milk was associated with arsenic in maternal blood, urine, and saliva. CONCLUSION: Very little arsenic is excreted in breast milk, even in women with high exposure from drinking water. Thus, exclusive breast-feeding protects the infant from exposure to arsenic.",
Arsenic,1355559,"Preconditioning with sodium arsenite inhibits apoptotic cell death in rat kidney with ischemia/reperfusion or cyclosporine-induced injuries: The possible role of heat-shock protein 70 as a mediator of ischemic tolerance Abstract: This study was performed to evaluate the effect of heat-shock protein (HSP)70 induction with sodium arsenite (SA) on ischemia/reperfusion (I/R) or cyclosporin A (CsA)-induced injuries in rat kidney. Rats were classified into five groups (sham, I/R, SA+I/R, I/R+CsA and SA+I/R+CsA groups) according to both the status of SA pretreatment and treatment with CsA. SA (6 mg/kg, i.v.) pretreatment was accomplished 12 h before I/R injury, and CsA (20 mg/kg, s.c.) was given subsequent to I/R injury. The effect of SA pretreatment on I/R injury was evaluated using measurements of renal function, the histopathology score, and assays for apoptosis (DNA fragmentation analysis, TUNEL staining, mRNA expressions of the pro-apoptotic genes and caspase activities). In addition, mitochondrial morphology was examined by electron microscopy. Induction of HSP70 with SA improved both renal function and the histopathology score as compared to the group without HSP70 induction. The assays for apoptosis revealed that SA pretreatment decreased the DNA laddering pattern, TUNEL-positive cells, mRNAs expression of pro-apoptotic genes and caspase activities as compared with the group without SA pretreatment. In addition, the mitochondrial morphology was well preserved in the groups with SA pretreatment. In conclusion, SA pretreatment prevents subsequent I/R or CsA-induced injuries in the rat kidney, and this renoprotective effect appears to be mediated by induction of HSP70.",
Arsenic,1329618,"An arsenite-inducible 19S regulatory particle-associated protein adapts proteasomes to proteotoxicity Abstract: Protein misfolding caused by exposure to arsenite is associated with transcriptional activation of the AIRAP gene. We report here that AIRAP is an arsenite-inducible subunit of the proteasome's 19S cap that binds near PSMD2 at the 19S base. Compared to the wild-type, knockout mouse cells or C. elegans lacking AIRAP accumulate more polyubiquitylated proteins and exhibit higher levels of stress when exposed to arsenite, and proteasomes isolated from arsenite-treated AIRAP knockout cells are relatively impaired in substrate degradation in vitro. AIRAP's association with the 19S cap reverses the stabilizing affect of ATP on the 26S proteasome during particle purification, and AIRAP-containing proteasomes, though constituted of 19S and 20S subunits, acquire features of hybrid proteasomes with both 19S and 11S regulatory caps. These features include enhanced cleavage of peptide substrates and suggest that AIRAP adapts the cell's core protein degradation machinery to counteract proteotoxicity induced by an environmental toxin.",
Arsenic,1022045,"Arsenic exposure to killifish during embryogenesis alters muscle development Abstract: Epidemiological studies have correlated arsenic exposure in drinking water with adverse developmental outcomes such as stillbirths, spontaneous abortions, neonatal mortality, low birth weight, delays in the use of musculature, and altered locomotor activity. Killifish (Fundulus heteroclitus) were used as a model to help to determine the mechanisms by which arsenic could impact development. Killifish embryos were exposed to three different sodium arsenite concentrations and were collected at 32 h post-fertilization (hpf), 42 hpf, 168 hpf, or &lt; 24 h post-hatch. A killifish oligo microarray was developed and used to examine gene expression changes between control and 25-ppm arsenic-exposed hatchlings. With artificial neural network analysis of the transcriptomic data, accurate prediction of each group (control vs. arsenic-exposed embryos) was obtained using a small subset of only 332 genes. The genes differentially expressed include those involved in cell cycle, development, ubiquitination, and the musculature. Several of the genes involved in cell cycle regulation and muscle formation, such as fetuin B, cyclin D-binding protein 1, and CapZ, were differentially expressed in the embryos in a time- and dose-dependent manner. Examining muscle structure in the hatchlings showed that arsenic exposure during embryogenesis significantly reduces the average muscle fiber size, which is coupled with a significant 2.1- and 1.6-fold upregulation of skeletal myosin light and heavy chains, respectively. These findings collectively indicate that arsenic exposure during embryogenesis can initiate molecular changes that appear to lead to aberrant muscle formation.",
Arsenic,2278440,"Development, characterization and evaluation of iron-coated honeycomb briquette cinders for the removal of As(V) from aqueous solutions Abstract: The adsorptive removal of As(V) from aqueous solutions using iron-coated honeycomb briquette cinder (Fe-HBC) is presented. Low cost mechanical granulation process was integrated with surface amendment technology to prepare iron-oxide modified granular adsorbent for clean water production. Detailed characterizations were performed using FTIR, XRD, EDS and SEM techniques. Operating parameters including initial As(V) concentration, pH, contact time, adsorbent dose, iron leaching and the effects of competing ions on As(V) removal were evaluated. Results demonstrated that high amount of arsenate (961.5 mu g g(-1)) was adsorbed at pH 7.5 in 14 h contact time. Langmuir, Freundlich and Temkin isotherm models were used to analyze the adsorption data, whereas Langmuir model was found to best represent the data with a correlation co-efficient (R-2 = 0.999). Thus, As(V) sorption on Fe-HBC surface suggested monolayer adsorption and indicated surface homogeneity. Moreover, the dimensionless parameter (R-L) value calculated to be about 0.118 that reiterated the process is favorable and spontaneous. The influences of competing ions on As(V) removal decreased in the following order: PO43-&gt; HCO3- &gt; F- &gt; Cl-. The profound inhibition effects of PO43- revealed a high affinity toward iron(oxy) hydroxide. Life-cycle assessment confirmed that spent HBC is non-hazardous and can be used as a promising sorbent for arsenic removal. (C) 2013 Production and hosting by Elsevier B. V. on behalf of King Saud University.",
Arsenic,2279199,"Removal of As(III) and As(V) from aqueous solutions using nanoscale zero valent iron-reduced graphite oxide modified composites Abstract: Nanoscale zero valent iron (NZVI) has high adsorption capacity of As(III) and As(V), but it is limited in practical use due to its small particle size and aggregation effect. Reduce graphite oxide (RGO) has been used as a support because of its high surface area. In order to utilize the advantage of NZVI and RGO as well as to avoid the disadvantage of NZVI, we loaded NZVI onto RGO via chemical reactions in this study. The adsorption capacity of As(III) and As(V), as determined from the Langmuir adsorption isotherms in batch experiments, was 35.83mgg(-1) and 29.04mgg(-1), respectively. And the adsorption kinetics fitted well with pseudo-second-order model. The residual concentration was found to meet the standard of WHO after the samples were treated with 0.4gL(-1) NZVI-RGO when the initial concentration of As(III) and As(V) were below 8ppm and 3ppm. Especially, when the initial concentration of As(III) was below 3ppm, the residual concentration was within 1ppb; whereas, the residual concentration was undetected when the initial concentration of As(III) was 1ppm.",
Arsenic,62181,"Prevalence of skin cancer in an endemic area of chronic arsenicism in Taiwan Abstract: In a limited area on the southwest coast of Taiwan where artesian well water with a high concentration of arsenic has been used for more than 45 years, a high prevalence of chronic arsenic poisoning has been observed in recent years. The total population of this endemic area, which is defined by the presence of both patients and contaminated wells, is approximately 100,000. A general survey of 40,421 inhabitants (19,269 males and 21,152 females) of the area was made. The overall prevalence rates for skin cancer, hyperpigmentation, and keratosis were 10.6, 183.5, and 71.0/1000, respectively. The male-to-female ratio was 2.9:1 for skin cancer and 1.1:1 for hyperpigmentation and keratosis, respectively. Generally speaking, the prevalence increased steadily with age in all three conditions, though there was a decline in age groups above 69 in females with cancer or hyperpigmentation. The prevalence rate for skin cancer showed an ascending gradient according to the arsenic content of the well water, i.e., the higher the arsenic content, the more patients with skin cancer. The results were the same for hyperpigmentation and keratosis. Blackfoot disease, so-termed locally, a peripheral vascular disorder resulting in gangrene of the extremities, especially of the feet, had an overall prevalence rate of 8.9/1000. A dose-response relationship between this disease and the amount of arsenic in the well water was similar to that observed for skin cancer. The association of Blackfoot disease with hyperpigmentation, keratosis, and skin cancer was significantly higher than expected. The casual relationship between Blackfoot disease and chronic arsenicism is discussed.",
Arsenic,2141409,"Rice consumption and urinary concentrations of arsenic in US adults Abstract: Exposure to inorganic arsenic in the general population occurs mainly from drinking water and food sources. This study examined the association between rice consumption and urinary concentrations of arsenic in US adults, aged 20-85 years, in the 2003-2006 National Health and Nutrition Examination Survey. Significantly higher geometric means of creatinine-corrected urinary concentrations of total arsenic (TAs) and dimethylarsinic acid (DMA) were found in participants who consumed rice more than twice per week, compared to the reference group. Multivariate logistic regression analysis revealed a statistically significant association between rice consumption and urinary concentrations of TAs [odds ratio (OR) = 1.51 (1.08, 2.09)] and DMA [OR = 2.24 (1.57, 3.21)] after adjustment for demographic variables, seafood intake (the main source of organic arsenic), and source of drinking water. Furthermore, significant variations in rice consumption and urinary concentrations of arsenic were observed in different racial groups. This study demonstrated that rice consumption contributed to inorganic arsenic exposure in US adults.",
Arsenic,1034251,"Cellular and biochemical events in mammalian cells during and after recovery from physiological stress Abstract: We have examined and compared a number of cellular and biochemical events associated with the recovery process of rat fibroblasts placed under stress by different agents. Metabolic pulse-labeling studies of cells recovering from either heat-shock treatment, exposure to sodium arsenite, or exposure to an amino acid analogue of proline, L-azetidine 2-carboxylic acid, revealed interesting differences with respect to the individual stress proteins produced, their kinetics of induction, as well as the decay in their synthesis during the recovery period. In the initial periods of recovery, the major stress-induced 72-kD protein accumulates within the altered nucleoli in close association with the pre-ribosomal-containing granular region. During the later times of recovery from stress, the nucleoli begin to regain a normal morphology, show a corresponding loss of the 72-kD protein, and the majority of the protein now begins to accumulate within the cytoplasm in three distinct locales: the perinuclear region, along the perimeter of the cells, and finally in association with large phase-dense structures. These latter structures appear to consist of large aggregates of phase-dense material with no obvious encapsulating membrane. More interestingly we show, using double-label indirect immunofluorescence analysis, that much of the perinuclear and cell perimeter-distributed 72-kD protein coincides with the distribution of the cytoplasmic ribosomes. We discuss the possible implications of the presence of the 72-kD stress proteins within the pre-ribosomal-containing granular region of the nucleolus as well as its subsequent colocalization with cytoplasmic ribosomes in terms of the translational changes which occur in cells both during and after recovery from physiological stress.",
Arsenic,1519097,"Surface interactions of aromatic organoarsenical compounds with hematite nanoparticles using ATR-FTIR: Kinetic studies Abstract: Aromatic organoarsenicals p-arsanilic acid (pAsA) and roxarsone (ROX) are used as feed additives in developing countries that allow the use of arsenic-containing compounds in their poultry industry. These compounds are introduced to the environment through the application of contaminated poultry litter. Little is known about the surface chemistry of these organoarsenicals on the molecular level with reactive components in soils. We report herein the first in situ and surface-sensitive rapid kinetic studies on the adsorption and desorption of pAsA to/from hematite nanoparticles at pH 7 using ATR-FTIR. Values for the apparent initial rates of adsorption and desorption were extracted from experimental data as a function of spectral components. Hydrogen phosphate was used as a desorbing agent due to its ubiquitous presence in litter, and its adsorption kinetics was investigated on surfaces with and without surface arsenic. Initial first-order pseudo-adsorption rate constant for pAsA was lower by a factor of 1.6 than that of iAs(V), suggesting an average behavior for the formation of quantitatively more weakly bonded monodentate or hydrogen-bonded complexes for the former relative to strongly bonded bidentate surface complexes for the latter under our experimental conditions. Initial first-order pseudo-adsorption rate constants for hydrogen phosphate decrease in this order: fresh hematite &gt; pAsA/hematite ? phenylarsonic acid (PhAs)/hematite &gt; iAs/hematite by factors 1.5 and 3 relative to fresh films, respectively. Initial desorption kinetics of aromatic organoarsenicals due to flowing hydrogen phosphate proceed with a nonunity overall order, suggesting a complex mechanism, which is consistent with the existence of more than one type of surface complexes. The impact of our studies on the environmental fate and transport of aromatic organoarsenicals in geochemical environments and their overall surface chemistry with iron (oxyhyr)oxides is discussed.",
Arsenic,2064249,"?-Hole bond versus hydrogen bond: From tetravalent to pentavalent N, P, and As atoms Abstract: Ab initio calculations were performed on complexes of ZH4 (+) (Z=N, P, As) and their fluoro derivatives, ZFH3 (+) and ZF4 (+) , with a HCN (or LiCN) molecule acting as the Lewis base through the nitrogen electronegative center. It was found that the complexes are linked by the Z--H???N hydrogen bond or another type of noncovalent interaction in which the tetravalent heavy atom of the cation acts as the Lewis acid center, that is, when the Z???N link exists, which may be classified as the ?-hole bond. The formation of the latter interaction is usually preferable to the formation of the corresponding hydrogen bond. The Z???N interaction may be also considered as the preliminary stage of the SN 2 reaction. This is supported by the observation that for a short Z???N contact, the corresponding complex geometry coincides with the trigonal-bipyramidal geometry typical for the transition state of the SN 2 reaction. The Z???N interaction for some of complexes analyzed here possesses characteristics typical for covalent bonds. Numerous interrelations between geometrical, topological and energetic parameters are discussed. The natural bond orbital method as well as the Quantum Theory of Atoms in Molecules is applied to characterize interactions in the analyzed complexes. The experimental evidences of the existence of these interactions, based on the Cambridge Structure Database search, are also presented. In addition, it is justified that mechanisms of the formation of the Z???N interactions are similar to the processes occurring for the other noncovalent links. The formation of Z???N interaction as well as of other interactions may be explained with the use of the ?-hole concept.",
Arsenic,2064162,"Impacts on groundwater recharge areas of megacity pumping: analysis of potential contamination of Kolkata, India, water supply Abstract: ",
Arsenic,1022231,"Arsenic methylation and bladder cancer risk in Taiwan Abstract: <strong>OBJECTIVE: </strong>The mechanism of arsenic detoxification in humans remains unclear. Data are especially lacking for low-level arsenic exposure. We hypothesize that arsenic methylation ability, defined as the ratios of monomethylarsonic acid (MMA(V))/inorganic arsenic (primary arsenic methylation index, PMI) and dimethylarsinic acid (DMA(V))/ MMA(V) (secondary arsenic methylation index, SMI), may modify the association between cumulative arsenic exposure (CAE, mg/L-year) and the risk of bladder cancer. In this study we investigated the relationship among arsenic methylation ability, CAE, and the risk of bladder cancer in a hospital-based case-control study in southwestern Taiwan.<br /><br /><strong>METHODS: </strong>From January 1996 to December 1999 we identified 49 patients with newly diagnosed cases of bladder cancer at the National Cheng-Kung University (NCKU) Medical Center; controls consisted of 224 fracture and cataract patients selected from the same medical center. The levels of four urinary arsenic species: arsenite (As(III)), arsenate (As(V)), MMA(V), and DMA(V)) were determined in all subjects by using the high-performance liquid chromatography hydride-generation atomic absorption spectrometry (HPLC-HGAAS). CAE was estimated by using published data collected in a survey from 1974 to 1976.<br /><br /><strong>RESULTS: </strong>Compared to a CAE &lt; or = 2 mg/L-year, CAE &gt; 12 mg/L-year was associated with an increased risk of bladder cancer (multivariate odds ratio (OR) 4.23, 95% confidence interval (CI) 1.12-16.01), in the setting of a low SMI (&lt; or = 4.8). Compared to women, smoking men (OR 6.23, 95% CI 1.88-20.62) and non-smoking men (OR 3.25, 95% CI 0.95-11.06) had higher risks of bladder cancer. Given the same level of PMI, smoking men (OR 9.80, 95% CI 2.40-40.10) and non-smoking men (OR 4.45, 95% CI 1.00-19.84) had a higher risk of bladder cancer when compared to women. With the same level of SMI, both smoking men (OR 6.28, 95% CI 1.76-22.39) and non-smoking men (OR 3.31, 95% CI 0.84-12.97) had a higher risk of bladder cancer when compared to women.<br /><br /><strong>CONCLUSIONS: </strong>Subjects with low SMI have a substantially increased risk of bladder cancer, especially when combined with high CAE levels.",
Arsenic,1519177,Limited Value of Cystatin-C over Estimated Glomerular Filtration Rate for Heart Failure Risk Stratification Abstract: ,
Arsenic,1597441,[Species of Arsenic in Rice Determination by means of HPLC-ICP-MS] Abstract: ,
Arsenic,2337191,"Arsenic(V) removal in wetland filters treating drinking water with different substrates and plants Abstract: Constructed wetlands are an attractive choice for removing arsenic (As) within water resources used for drinking water production. The role of substrate and vegetation in As removal processes is still poorly understood. In this study, gravel, zeolite (microporous aluminosilicate mineral), ceramsite (lightweight expanded clay aggregate) and manganese sand were tested as prospective substrates while aquatic Juncus effuses (Soft Rush or Common Rush) and terrestrial Pteris vittata L. (Chinese Ladder Brake; known as As hyperaccumulator) were tested as potential wetland plants. Indoor batch adsorption experiments combined with outdoor column experiments were conducted to assess the As removal performances and process mechanisms. Batch adsorption results indicated that manganese sand had the maximum As(V) adsorption rate of 4.55 h(-1) and an adsorption capacity of 42.37 ?g/g compared to the other three aggregates. The adsorption process followed the pseudo-first-order kinetic model and Freundlich isotherm equations better than other kinetic and isotherm models. Film-diffusion was the rate-limiting step. Mean adsorption energy calculation results indicated that chemical forces, particle diffusion and physical processes dominated As adsorption to manganese sand, zeolite and gravel, respectively. During the whole running period, manganese sand-packed wetland filters were associated with constantly 90% higher As(V) reduction of approximate 500 ?g/L influent loads regardless if planted or not. The presence of P. vittata contributed to no more than 13.5% of the total As removal. In contrast, J. effuses was associated with a 24% As removal efficiency.",
Arsenic,626995,"Dithiol compounds at low concentrations increase arsenite toxicity Abstract: Inorganic trivalent arsenicals are vicinal thiol-reacting agents, and dithiothreitol (DTT) is a well-known dithiol agent. Interestingly, both decreasing and increasing effects of DTT on arsenic trioxide–induced apoptosis have been reported. We now provide data to show that, at high concentrations, DTT, dimercaptosuccinic acid (DMSA), and dimercaptopropanesulfonic acid (DMPS) decreased arsenic trioxide–induced apoptosis in NB4 cells, a human promyelocytic leukemia cell line. In contrast, at low concentrations DTT, DMSA, and DMPS increased the arsenic trioxide–induced apoptosis. DTT at a high concentration (3 mM) decreased, whereas at a low concentration (0.1 mM), it increased the cell growth inhibition of arsenic trioxide, methylarsonous acid (MMAIII), and dimethylarsinous acid (DMAIII) in NB4 cells. DMSA and DMPS are currently used as antidotes for acute arsenic poisoning. These two dithiol compounds also show an inverse-hormetic effect on arsenic toxicity in terms of DNA damage, micronucleus induction, apoptosis, and colony formation in experiments using human epithelial cell lines derived from arsenic target tissues such as the kidney and bladder. With the oral administration of dithiols, the concentrations of these dithiol compounds in the human body are likely to be low. Therefore, the present results suggest the necessity of reevaluating the therapeutic effect of these dithiol compounds for arsenic poisoning.",
Arsenic,1508553,"Changes in catchment conditions lead to enhanced remobilization of arsenic in a water reservoir Abstract: Increasing arsenic concentrations in freshwater ecosystems is of global concern. Processes affecting arsenic fluxes in catchments are known. These processes are in turn controlled by the underlying geology and air pollution history. In contrast to the knowledge on catchment processes less is known about the hydrochemical processes controlling the fixation/remobilization of arsenic within lakes and artificial reservoirs. Consequently, we examined a reservoir system in the Ore Mts. (Germany) regarding its sink and source potentials affecting arsenic fluxes. This area was faced with heavy deposition inputs from coal burning based acid rain until the beginning of the 1990s. Hereafter concentrations of sulfate and nitrate in runoff waters decreased, whereas dissolved organic carbon (DOC) concentrations are still increasing. Along with this, arsenic concentrations in the water discharge from the catchments increase. Our results reveal that the sediments of the investigated reservoir system contain high inventories of arsenic in association with ferric and organic phases. A nitrate deficit dependent arsenic release is suggested. It is indicated that arsenic release from the reservoir sediments may be controlled by water nitrate concentration, which in turn is dependent on the nitrate concentration in the runoff water from the catchment.",
Arsenic,1034126,"The potent heme oxygenase inducing action of arsenic and parasiticidal arsenicals Abstract: The administration of trivalent arsenic, either as sodium arsenite or as the trypanocidal drug melarsoprol, to rats produced a profound induction of microsomal heme oxygenase (EC 1.14.99.3) in both liver and kidney and a concomitant decrease in cytochrome P-450 content. In addition, perturbations of delta-aminolevulinate synthase were observed which showed an initial decline followed by a rebound increase in the activity of this enzyme with arsenical treatment. Pentavalent arsenic did not induce hepatic heme oxygenase but did induce the enzyme in kidney, although to a lesser extent (50%) than trivalent arsenic. Treatment of isolated chick embryo liver cells in vitro with sodium arsenite or the parasiticidal drug melarsoprol also showed a potent induction of heme oxygenase. These findings describe a new and potent ability of arsenic and parasiticidal arsenicals to induce heme oxygenase resulting in enhanced degradation of cellular heme.",
Arsenic,1020209,"Differential effects of arsenic on folate binding protein 2 (Folbp2) null and wild type fibroblasts Abstract: Exposure to arsenic results in a wide variety of adverse effects. It has been postulated that one mechanism of arsenic toxicity is disruption of cellular methyl biochemistry. Because dietary folate is required to generate the methyl donor S-adenosyl methionine, we hypothesized that loss of folate binding protein 2 (Folbp2) results in increased susceptibility to arsenic-induced cytotoxicity. Using Folbp2 +/+ and -/- fibroblasts, we determined that Folbp2 null cells display increased sensitivity to arsenic exposure. Folic acid supplementation partially rescues wild type cells from arsenic toxicity, but Folbp2 null cells are not protected. Arsenic inhibits folic acid uptake in Folbp2 null fibroblasts, but not wild type cells; baseline uptake is similar in both cell types. These results support the possibility that arsenic toxicity occurs, in part, by perturbing cellular methyl biochemistry. Furthermore, identification of Folbp2 as a protective protein presents an opportunity to identify populations at increased risk for serious effects of arsenic exposure.",
Arsenic,1340663,"DNA-PKcs-mediated stabilization of p53 by JNK2 is involved in arsenite-induced DNA damage and apoptosis in human embryo lung fibroblast cells Abstract: When cells encounter genotoxic stress, sensors for DNA lesions stabilize and activate p53; the signals involved, however, are largely unclear. Inorganic arsenite is a ubiquitous environmental contaminant associated with an increased risk of lung and skin damage and cancer. Although DNA double-strand breaks and apoptosis may relate to arsenite-induced damage and carcinogenesis, the mechanism of action remains obscure. Here, we find that, in human embryo lung fibroblast (HELF) cells, arsenite induces the activation of dependent protein kinase catalytic subunit (DNA-PKcs), which then phosphorylates and activates c-Jun N-terminal kinases 2 (JNK2), but not JNK1. As a positive regulator of p53, JNK2 binds to p53 and prevents p53 from murine double minute 2 (mdm2)-mediated, ubiquitin-proteasome-dependent degradation. Knockdown of DNA-PKcs/JNK2 signal pathway or p53 reduces apoptosis but elevates the DNA damage induced by a high level of arsenite. These results suggest that DNA-PKcs-mediated stabilization of p53 by JNK2 is involved in arsenite-induced DNA damage and apoptosis.",
Arsenic,656747,"Skin cancer induced by arsenic in the water Abstract: BACKGROUND: Arsenic (As) is a well-recognized poison. Exposure may be of an acute nature, leading to high concentrations and acute arsenic poisoning. Chronic exposure may lead to benign skin changes, skin cancer, and internal malignancy. OBJECTIVE: Our purpose was to study the nature, incidence, and sequelae of skin disorders in a group of Argentinean patients suffering from chronic arsenicism due to the intake of contaminated well water. METHODS: All patients who presented with chronic arsenicism at the Dermatology Department of Hospital Posadas (Buenos Aires, Argentina) during a 10-year period (1988-1998) were included in this study. The patient group compromised 9 women and 14 men, the age range was 37-72 years. Diagnosis was based on the clinical triad (keratoderma, leucoderma and epiteliomatosis). We performed clinical, laboratory, and histopathologic studies to confirm diagnosis. We screened for possible internal diseases. RESULTS: All patients included in this study had cutaneous lesions associated with long-term arsenic exposure. The mean age of the patients was 58.2 years. The estimated mean time of the beginning of the lesions was of 3.7 years. All patients were Argentinean from endemic areas of our country where the arsenic levels are higher than those accepted by the World Health Organization. CONCLUSION: This study allows us to conclude that the relationship between arsenic and cancer is frequent and it describes the principal characteristics of this entity in our group of patients.",
Arsenic,657865,"The role of trivalent dimethylated arsenic in dimethylarsinic acid-promoted skin and lung tumorigenesis in mice: Tumor-promoting action through the induction of oxidative stress Abstract: We investigated the relationship between lung- and skin-tumor promotion and oxidative stress caused by administration of dimethylarsinic acid (DMA(V)) in mice. The incidence of lung tumors induced by lung tumor initiator (4NQO) and DMA(V) were, as well as 8-oxo-2?-deoxyguanosine (8-oxodG), suppressed by cotreatment with (?)epigallocatechin gallate (EGCG). When mice were topically treated with trivalent dimethylated arsenic (DMA(III)), a further reductive metabolite of DMA(V), not only an increase in skin tumors but also an elevation of 8-oxodG in epidermis were observed. These results suggest that tumor promotion due to DMA(V) administration is mediated by DMA(III) through the induction of oxidative stress.",
Arsenic,1019924,"Arsenic(III), but not antimony(III), induces DNA-protein crosslinks Abstract: Antimony compounds are supposed to resemble to arsenicals in some toxicological features. Comparative investigations with antimony and arsenic were performed to collect data on the genotoxicity of antimony, on which the knowledge is scarce. In comparison to trivalent arsenic, trivalent antimony proved to be five times less cytotoxic in the neutral red assay and one order of magnitude less genotoxic in the cytokinesis-block micronucleus test using V79 Chinese hamster cells. The data obtained in the comet assay showed that the As(III)-mediated generation of DNA-protein crosslinks and DNA strand lesions seem to be two independent processes. In contrast, Sb(III) induced DNA strand lesions but not DNA-protein crosslinks. Further studies will have to investigate whether the genotoxicity of Sb(III) is mediated by an inhibition of DNA repair as it seems to be the case for As(III).",
Arsenic,1345316,"Cytokine-induced nitric oxide synthase gene transcription is blocked by the heat shock response in human liver cells Abstract: <strong>BACKGROUND: </strong>Previously we demonstrated that the heat shock response (HSR) inhibits cytokine-stimulated nitric oxide (NO) synthesis and inducible NO synthase (NOS2) expression in hepatocytes. In this study we sought to determine the molecular basis of this inhibition using a human liver cell line.<br /><br /><strong>METHODS: </strong>After induction of the HSR by sodium arsenite or hyperthermia, the AKN-1 human liver cell line was treated with cytokines to stimulate NOS2 expression and NO production. Western blot analysis for hsp70 was performed, and NOS2 mRNA and 24-hour NO synthesis were quantitated. Cytokine-induced NOS2 promoter activity of AKN-1 cells transfected with a 7.0 kilobase NOS2 promoter luciferase construct and NO production of AKN-1 cells transduced with the NOS2 gene were measured.<br /><br /><strong>RESULTS: </strong>Sodium arsenite or hyperthermia induced the synthesis of hsp70 protein in AKN-1 cells, indicating activation of the HSR. Cytokines stimulated high levels of NOS2 mRNA and NO production. However, prior induction of the HSR significantly inhibited NOS2 expression and NO synthesis. Cytokine-stimulated NOS2 promoter activity of transfected AKN-1 cells was decreased by 77%, but the HSR did not affect NOS2 enzyme activity in transduced AKN-1 cells.<br /><br /><strong>CONCLUSIONS: </strong>These findings indicate that the HSR inhibits cytokine-induced NOS2 expression and NO synthesis in AKN-1 cells by preventing NOS2 promoter activation. Effects on NOS2 protein translation or stability were not observed. These data suggest that the HSR, which is expressed in the liver after trauma, shock, or ischemia-reperfusion, blocks NOS2 gene expression at the transcriptional level.",
Arsenic,1358046,"Sequential slew scanning monochromator as a plasma emission chromatographic detector for determination of volatile hydrides Abstract: A sequential determination of chromatographically separated hydrides has been developed to demonstrate the use of a sequential slew scanning monochromator as a plasma emission chromatographic detector. Hydrides of Ge, As, and Sb are generated, separated on a column of CHromosorb 102, and introduced into an inductively coupled plasma. The sequential slew monochromator monitors each resolved chromatographic peak at a different atomic emission wavelength. The detection limits are 0.004 ug (0.20 ppb) for Ge and 0.05 ug (2.5 ppb) for As and Sb. Relative standard deviations at the 1 ug (50 ppb) level range from 2 t 5%. Accuracy of the method is demonstrated by analysis of EPA water quality control reference standards.",
Arsenic,2064257,"Remarkable efficiency of ultrafine superparamagnetic iron(III) oxide nanoparticles toward arsenate removal from aqueous environment Abstract: Arsenates, when present in water resources, constitute a risk to human health. In order to remove them, various technologies have been developed; out of them, sorption approach is widely adopted employing a wide spectrum of suitable sorbent materials. Nanoparticles of iron oxide are frequently used due to a high surface area and ability to control them by external magnetic field. In this work, we report on a simple and cheap synthesis of ultrafine iron(III) oxide nanoparticles with a narrow size distribution and their exploitation in the field of arsenate removal from aqueous environment. It is shown that the adsorption capacity is enhanced by a mesoporous nature of nanoparticle arrangement in their system due to strong magnetic interactions they evolve between nanoparticles. A complete arsenate removal is achieved at Fe/As ratio equal to ?20/1 and at pH in the range from 5 to 7.6. Under these conditions, the arsenates are completely removed within several minutes of treatment. Among iron-oxide-based nanosystems synthesized and employed in arsenate remediation issues so far, our assembly of iron(III) oxide nanoparticles shows the highest Freundlich adsorption coefficient and equilibrium sorption capacity under conditions maintained. Taking into account simple and low-cost preparation procedure, product high yields, almost monodispersed character, room-temperature superparamagnetic behavior, and strong magnetic response under small applied magnetic fields, the synthesized iron(III) oxide nanoparticles can be regarded as a promising candidate for exploitation in the field of removing undesired toxic pollutants from various real water systems.",
Arsenic,708296,"Long-term effects on male reproduction of early exposure to common chemical contaminants in drinking water Abstract: We evaluated sequelae to early exposure of male rabbits to drinking water containing chemicals typical of ground water near hazardous waste sites. The mixture (p.p.m. at 1x) was 7.75 arsenic, 1.75 chromium, 9.25 lead, 12.5 benzene, 3.75 chloroform, 8.5 phenol and 9.5 trichloroethylene. Dutch-Belted does received mixture at 0x (deionized water; control), 1x or 3x as drinking water from day 20 pregnancy through weaning. Exposure of individual males (7-9/treatment) continued until 15 weeks (adolescence); then, all males received deionized water. At 57-61 weeks of age, ejaculatory capability and seminal, testicular, epididymal and endocrine characteristics were evaluated. At 10 opportunities with a female teaser, all seven control males ejaculated every time, but 12 of the 17 treated males failed to express interest, achieve erection and/or ejaculate on one to five occasions; four of the 12 accomplished ejaculation with a second male teaser. Total spermatozoa/ejaculate and daily sperm production were unaffected. However, treatment caused (P < 0.03) acrosomal dysgenesis and nuclear malformations. Baseline serum concentrations of LH were lower, but with borderline significance (P = 0.05). Testosterone secretion after exogenous human chorionic gonadotrophin (P < 0.04) was low. Thus, even at 45 weeks after last exposure to drinking water pollutants, mating desire/ability, sperm quality, and Leydig cell function were subnormal.",
Arsenic,1797819,"Diagnostic analysis of veterinary dried blood spots for toxic heavy metals exposure Abstract: Dried blood spots (DBS) on filter paper have been used in human medicine since the 1960s, predominantly for screening in-borne metabolic disorders and more recently, for toxicology. Despite its 50-year existence, this technology has not been adopted by veterinarians for routine diagnoses and research. We have validated a novel DBS analytical procedure for the routine measurement of toxic heavy metals using 50 µL of whole blood on a single DBS by inductively coupled plasma mass spectrometry (ICP-MS). Targeted heavy metals are arsenic, cadmium, mercury, lead, selenium and thallium. The limits of quantitation (LOQ) on DBS are: arsenic 1.7 µg/L, cadmium 4.0 µg/L, mercury 13.7 µg/L, lead 13.3 µg/L, selenium 6.3 µg/L and thallium 1.5 µg/L. These LOQs suffice for routine diagnoses of heavy metal intoxication in domesticated and wildlife species as well as for basic, applied and epidemiological studies. The technique is ideal for population studies involving investigations of wildlife exposure to heavy metals and other environmental pollutants. The small blood volume involved (50 µL) makes it feasible to study small animals (birds, reptiles, amphibians and small mammals) that were previously excluded, or difficult to study due to the relatively large sample volumes required by current gold standard blood collection techniques.",
Arsenic,2345682,"Intra-specific variability in the response of maize to arsenic exposure Abstract: The response of maize (Zea mays L.) to inorganic arsenic exposure was studied, at the seedling stage under hydroponic conditions, preliminarily in sixteen lines (fourteen hybrids and two inbred lines) and then, more deeply, in six of these lines, selected by showing contrasting differences in their sensitivity to the metalloid. The results indicated that (i) maize is rather tolerant to arsenic toxicity, (ii) arsenite is more phytotoxic than arsenate, (iii) roots are less sensitive than shoots to the metalloid, (iv) a great accumulation of non-protein thiols (probably phytochelatins), without substantial effect on the glutathione content, is produced in roots but not in shoots of arsenic-exposed plants and (v) maize is able to accumulate high levels of arsenic in roots with very low translocation to shoots. The study, thus, suggests that maize, for its very low rate of acropetal transport of arsenic from roots to shoots, may be a safe crop in relation to the risk of entry of metalloid in the food chain and, for being an important bioenergy crop capable of expressing high levels of arsenic tolerance and accumulation in roots, may represent an interesting opportunity for the exploitation of agricultural useless arsenic contaminated lands.",
Arsenic,1797796,"Biomechanical characteristics of bone in streptozotocin-induced diabetic rats: An in-vivo randomized controlled experimental study Abstract: <strong>AIM: </strong>To investigate the in vivo effects of type?I?diabetes on the mechanical strength of tibial bone in a rodent model.<br /><br /><strong>METHODS: </strong>The biomechanical effect of diabetes on the structural integrity of the tibia in streptozotocin induced diabetic Wistar rats was analysed. Induction of diabetes was achieved by an intra-peritoneal injection and confirmed by measuring serial blood glucose levels (&gt; 150 mg/dL). After 8 wk the tibiae were harvested and compared to a control group. Biomechanical analysis of harvested tibiae was performed using a three-point bending technique on a servo hydraulic MTS 858 MiniBionix frame. Maximum force applied to failure (N), stiffness (N × mm) and energy absorbed (N/mm) were recorded and plotted on load displacement curves. A displacement control loading mode of 1 mm/min was selected to simulate quasi-static loading conditions. Measurements from load-displacement curves were directly compared between groups.<br /><br /><strong>RESULTS: </strong>Fourteen streptozotocin induced diabetic Wistar rats were compared against nineteen non-diabetic controls. An average increase of 155.2 g in body weight was observed in the control group compared with only 5 g in the diabetic group during the experimental study period. Levels of blood glucose increased to 440.25 mg/dL in the diabetic group compared to 116.62 mg/dL in the control group.The biomechanical results demonstrate a highly significant reduction in the maximum load to failure from 69.5 N to 58 N in diabetic group compared to control (P = 0.011). Energy absorption to fracture was reduced from 28.2 N in the control group to 23.5 N in the diabetic group (P = 0.082). No significant differences were observed between the groups for bending stiffness.<br /><br /><strong>CONCLUSION: </strong>Streptozotocin-induced diabetes in rodents reduces the maximum force and energy absorption to failure of bone, suggesting a predisposition for fracture risk.",
Arsenic,1026012,"Socioeconomic and country variations in knowledge of health risks of tobacco smoking and toxic constituents of smoke: results from the 2002 International Tobacco Control (ITC) Four Country Survey Abstract: <strong>BACKGROUND: </strong>Socioeconomic status is strongly associated with smoking prevalence and social class differences contribute substantially to social inequalities in mortality. This research investigated socioeconomic and country variations in smokers' knowledge that smoking causes heart disease, stroke, impotence and lung cancer, that smoke contains cyanide, mercury, arsenic and carbon monoxide, and whether nicotine causes most of the cancer.<br /><br /><strong>METHODS: </strong>Data were from the International Tobacco Control (ITC) Four Country Survey, a cohort survey of over 9000 adult smokers from four countries: the United States, Canada, the United Kingdom, and Australia. Data were collected via telephone interviews in 2002.<br /><br /><strong>RESULTS: </strong>Higher education and income were associated with higher awareness. For example, the odds of knowing that smoking causes heart disease, stroke and lung cancer were respectively 71%, 34% and 83% larger for respondents with high versus low income. The odds of knowing that smoke contains cyanide, mercury, arsenic and carbon monoxide were respectively 66%, 26%, 44% and 108% larger for respondents with a university degree than those with a high school diploma or lower level of education. Results also revealed that awareness of harms of smoking was generally the highest in Canada and the lowest in the UK.<br /><br /><strong>CONCLUSIONS: </strong>Lower socioeconomic status was associated with lower awareness of the harms of smoking and misunderstanding around nicotine. There is a need to improve knowledge of the dangers of smoking among the disadvantaged segments of the population.",
Arsenic,2298691,"Expression of the sFLT1 gene in cord blood cells is associated to maternal arsenic exposure and decreased birth weight Abstract: There is increasing epidemiologic evidence that arsenic exposure in utero is associated with adverse pregnancy outcomes and may contribute to long-term health effects. These effects may occur at low environmental exposures but the underlying molecular mechanism is not clear. We collected cord blood samples of 183 newborns to identify associations between arsenic levels and birth anthropometric parameters in an area with very low arsenic exposure. Our core research aim was to screen for transcriptional marks that mechanistically explain these associations. Multiple regression analyses showed that birth weight decreased with 47 g (95% CI: 16-78 g) for an interquartile range increase of 0.99 ?g/L arsenic. The model was adjusted for child's sex, maternal smoking during pregnancy, gestational age, and parity. Higher arsenic concentrations and reduced birth weight were positively associated with changes in expression of the sFLT1 (soluble fms-like tyrosine kinase-1) gene in cord blood cells in girls. The protein product of sFLT1 is a scavenger of vascular endothelial growth factor (VEGF) in the extracellular environment and plays a key role in the inhibition of placental angiogenesis. In terms of fetal development, inhibition of placental angiogenesis leads to impaired nutrition and hence to growth retardation. Various genes related to DNA methylation and oxidative stress showed also changed expression in relation to arsenic exposure but were not related to birth outcome parameters. In conclusion, this study suggests that increased expression of sFLT1 is an intermediate marker that points to placental angiogenesis as a pathway linking prenatal arsenic exposure to reduced birth weight.",
Arsenic,2216534,"Arsenic-induced Aurora-A activation contributes to chromosome instability and tumorigenesis Abstract: Arsenic may cause serious environmental pollution and is a serious industrial problem. Depending on the dosage, arsenic may trigger the cells undergoing either proliferation or apoptosis-related cell death. Because of lack of the proper animal model to study arsenic induced tumorigenesis, the accurate risk level of arsenic exposure has not been determined. Arsenic shows genotoxic effect on human beings who uptake water contaminated by arsenic. Chromosome aberration is frequently detected in arsenic exposure-related diseases and is associated with increased oxidative stress and decreased DNA repairing activity, but the underlying mechanism remains elusive. Aurora-A is a mitotic kinase, over-expression of Aurora-A leads to centrosome amplification, chromosomal instability and cell transformation. We revealed that Aurora-A is over-expressed in the skin and bladder cancer patients from blackfoot-disease endemic areas. Our cell line studies reveal that arsenic exposure between 0.5 ?M and 1 ?M for 2–7 days are able to induce Aurora-A expression and activation based on promoter activity, RNA and protein analysis. Aurora-A overexpression further increases the frequency of unsymmetrical chromosome segregation through centrosome amplification followed by cell population accumulated at S phase in immortalized keratinocyte (HaCaT) and uroepithelial cells (E7). Furthermore, Aurora-A over-expression was sustained for 1–4 weeks by chronic treatment of immortalized bladder and skin cells with NaAsO2. Aurora-A promoter methylation and gene amplification was not detected in the long-term arsenic treated E7 cells. Furthermore, the expression level of E2F1 transcription factor (E2F1) is increased in the presence of arsenic, and arsenic-related Aurora-A over-expression is transcriptionally regulated by E2F1. We further demonstrated that overexpression of Aurora-A and mutant Ha-ras or Aurora-A and mutant p53 may act additively to trigger arsenic-related bladder and skin cancer formation, respectively. It indicates that from chromosome instability proceeding to tumorigenesis, the simultaneous action of Aurora-A with activated oncogenic factor or inactivated tumor suppressor is required. In summary, we hypothesize that low concentration (0.5–1 ?M) of arsenic-induced E2F1-Aurora-A signaling pathway results in aberrant chromosome distribution during cell mitosis, the abnormal mitotic cells proceed to cancer cells only after acquiring additional tumorigenic factors. Our studies suggest that inhibition of low concentration of arsenic induced Aurora-A expression may provide a new theraputical strategy for the prevention and treatment of arsenic-related cancers.",
Arsenic,2064163,"Physiological Effects of Exposure to Arsenic, Mercury, Antimony and Selenium in the Aquatic Moss Fontinalis antipyretica Hedw Abstract: ",
Arsenic,1070419,"Arsenic triggers the nitric oxide (NO) and S-nitrosoglutathione (GSNO) metabolism in Arabidopsis Abstract: Environmental contamination by arsenic constitutes a problem in many countries, and its accumulation in food crops may pose health complications for humans. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved at various levels in the mechanism of responding to environmental stress in higher plants. Using Arabidopsis seedlings exposed to different arsenate concentrations, physiological and biochemical parameters were analyzed to determine the status of ROS and RNS metabolisms. Arsenate provoked a significant reduction in growth parameters and an increase in lipid oxidation. These changes were accompanied by an alteration in antioxidative enzymes and the nitric oxide (NO) metabolism, with a significant increase in NO content, S-nitrosoglutathione reductase (GSNOR) activity and protein tyrosine nitration as well as a concomitant reduction in glutathione and S-nitrosoglutathione (GSNO) content. Our results indicate that 500 ?M arsenate (AsV) causes nitro-oxidative stress in Arabidopsis, being the glutathione reductase and the GSNOR activities clearly affected.",
Arsenic,1328168,"Acute exposure to arsenite induces metallothionein isoform-specific gene expression in human proximal tubule cells Abstract: The expression of metallothionein (MT) mRNA and protein was determined in human proximal tubule cells (HPT) following acute exposure to the classic stimulators of the stress response, heat and sodium arsenite (As3+). Treatment of the cells with 100 microM As3+ for 4 h resulted in a significant increase in the MT-1 and MT-2 proteins immediately preceding and following removal of the stress. The level of the MT-3 isoform protein was unchanged as a result of As3+ treatment. An analysis of the MT isoform-specific mRNA demonstrated that control cells express the MT-1E, MT-1F, MT-1X, MT-2A, and MT-3 genes, but not the MT-1A, MT-1B, MT-1C, MT-1H, and MT-4 genes. Treatment with As3+ resulted in a significant increase in the expression of the MT-1X gene and appearance of mRNA for the MT-1A gene. Expression of the other MT genes was unaffected by As3+ exposure, except one isolate expressed a low level of MT-1G mRNA at several time points. It is likely that the increase in MT protein seen in As3+-treated cells is due to the increased expression of the MT-1X gene because its expression is much greater than the MT-1A isoform. Treatment of the HPT cells with heat shock had no marked effect on the levels of MT protein or mRNA. This study demonstrates that acute exposure to As3+ increases the levels of MT protein and that this elevation most likely arises from increased expression of the MT-1X isoform.",1
Arsenic,1508723,"HAX-1 is a nucleocytoplasmic shuttling protein with a possible role in mRNA processing Abstract: HAX-1 is a multi-functional protein that is involved in the regulation of apoptosis, cell motility and calcium homeostasis. It is also reported to bind RNA: it associates with structural motifs present in the 3' untranslated regions of at least two transcripts, but the functional significance of this binding remains unknown. Although HAX-1 has been detected in various cellular compartments, it is predominantly cytoplasmic. Our detailed localization studies of HAX-1 isoforms revealed partial nuclear localization, the extent of which depends on the protein isoform. Further studies demonstrated that HAX-1 is in fact a nucleocytoplasmic shuttling protein, dependent on the exportin 1 nuclear export receptor. Systematic mutagenesis allowed identification of the two nuclear export signals in the HAX-1 sequence. HAX-1 nuclear accumulation was observed after inhibition of nuclear export by leptomycin B, but also after specific cellular stress. The biological role of HAX-1 nuclear localization and shuttling remains to be established, but the HAX-1 transcript-binding properties suggest that it may be connected to mRNA processing and surveillance. In this study, HAX-1 status was shown to influence mRNA levels of DNA polymerase ?, one of the HAX-1 mRNA targets, although this effect becomes pronounced only after specific stress is applied. Moreover, HAX-1 tethering to the reporter transcript caused a significant decrease in its expression. Additionally, the HAX-1 co-localization with P-body markers, reported here, implies a role in mRNA processing. These results suggest that HAX-1 may be involved in the regulation of expression of bound transcripts, possibly as part of the stress response.",
Arsenic,1337485,"Identification and profiling of arsenic stress-induced microRNAs in Brassica juncea Abstract: MicroRNAs (miRNAs) constitute a novel mechanism of gene regulation affecting plant development, growth, and stress response. To study the role of miRNAs in arsenic (As) stress, microarray profiling of miRNAs was performed in Brassica juncea using a custom Phalanx Plant OneArray™ containing 381 unique miRNA probes representing 618 miRNAs from 22 plant species. miRNA microarray hybridization of roots exposed to As for 1h and 4h revealed that a total of 69 miRNAs belonging to 18 plant miRNA families had significantly altered expression. The As-responsive miRNAs also exhibited a time- and organ-dependent change in their expression. Putative target prediction for the miRNAs suggested that they regulate various developmental processes (e.g. miR156, miR169, and miR172), sulphur uptake, transport, and assimilation (miR395, miR838, and miR854), and hormonal biosynthesis and/or function (e.g. miR319, miR167, miR164, and miR159). Notable changes were observed in the level of auxins [indole-3-acetic acid (IAA), indole-3- butyric acid, and naphthalene acetic acid], jasmonates [jasmonic acid (JA) and methyl jasmonate], and abscisic acid. The exogenous supply of JA and IAA improved growth of plants under As stress and altered expression of miR167, miR319, and miR854, suggesting interplay of hormones and miRNAs in the regulation of As response. In conclusion, the present work demonstrates the role of miRNAs and associated mechanisms in the plant's response towards As stress.",
Arsenic,834600,"As(III) inhibits ultraviolet radiation-induced cyclobutane pyrimidine dimer repair via generation of nitric oxide in human keratinocytes Abstract: Inorganic arsenic enhances skin tumor formation when combined with other carcinogens including ultraviolet radiation (UVR). The inhibition of DNA damage repair by arsenic has been hypothesized to contribute to the cocarcinogenic activities of arsenic observed in vivo. Cyclobutane pyrimidine dimers (CPDs) are an important mutagenic UVR photoproduct and implicated in the genesis of nonmelanoma skin cancer. The current study demonstrates that low concentrations of arsenite (As(III)) inhibit UVR-induced CPD repair in a human keratinocyte cell line via nitric oxide (NO) and inducible nitric oxide synthase (iNOS). Following As(III) treatment, NO production and iNOS expression are elevated. Little is known about regulation of iNOS by As(III) and further investigations indicated that p38 mitogen-activated protein kinase (p38 MAPK) and NF-kappaB are required for As(III) induction of iNOS expression. This As(III)-stimulated signaling cascade was involved in inhibition of UVR-induced CPD repair as disruption of p38 MAPK activity and NF-kappaB nuclear translocation counteracted the effects of As(III) on CPD repair. Selective inhibition of iNOS ameliorated As(III) inhibition of CPD repair, thereby suggesting that iNOS is a downstream mediator of As(III) activity. These findings provide evidence that an As(III)-stimulated signal transduction cascade culminating in elevated iNOS expression and NO generation is an underlying mechanism for inhibition of UVR-induced DNA damage repair by arsenic.",
Arsenic,1026618,"Assessment of public health risks associated with atmospheric exposure to PM2.5 in Washington, DC, USA Abstract: In this research, we investigated the public health risks associated with atmospheric exposure to PM2.5 for different subpopulations (black, white, Hispanic, youth, adults, and elderly) in the Washington, DC area. Washington, DC has long been considered a non-healthy place to live according to the American Lung Association due to its poor air quality. This recognition clearly includes the negative PM-related human health effects within the region. Specifically, DC fine particulate matter (PM2.5) [or particulate matter with an aerodynamic diameter less than 2.5 microm] poses notable health risks to subpopulations having an annual mean value of 16.70 microg/m(3) during the years 1999-2004, exceeding the EPA National Ambient Air Quality Standard (NAAQS) of 15 microg/m(3). Incessant exposure to significant levels of PM has previously been linked to deleterious health effects, such as heart and lung diseases. The environmental quality and public health statistics of Washington, DC indicate the need for higher-resolution measurements of emissions, both spatially and temporally, and increased analysis of PM-related health effects. Our findings show that there are significant risks of ward-specific pediatric asthma emergency room visits (ERV). Results also illustrate lifetime excess lung cancer risks, exceeding the 1 x 10(-6) threshold for the measured levels of particulate matter and heavy metals (chromium and arsenic) on behalf of numerous subpopulations in the DC selected wards.",
Arsenic,107905,"Elucidating the pathway for arsenic methylation Abstract: Although biomethylation of arsenic has been studied for more than a century, unequivocal demonstration of the methylation of inorganic arsenic by humans occurred only about 30 years ago. Because methylation of inorganic arsenic activates it to more reactive and toxic forms, elucidating the pathway for the methylation of this metalloid is a topic of considerable importance. Understanding arsenic metabolism is of public health concern as millions of people chronically consume drinking water that contains high concentrations of inorganic arsenic. Hence, the focus of our research has been to elucidate the molecular basis of the steps in the pathway that leads from inorganic arsenic to methylated and dimethylated arsenicals. Here we describe a new S-adenosylmethionine (AdoMet)-dependent methyltransferase from rat liver cytosol that catalyzes the conversion of arsenite to methylated and dimethylated species. This 42-kDa protein has sequence motifs common to many non-nucleic acid methyltransferases and is closely related to methyltransferases of previously unknown function that have been identified by conceptual translations of cyt19 genes of mouse and human genomes. Hence, we designate rat liver arsenic methyltransferase as cyt19 and suggest that orthologous cyt19 genes encode an arsenic methyltransferase in the mouse and human genomes. Our studies with recombinant rat cyt19 find that, in the presence of an exogenous or a physiological reductant, this protein can catalyze the entire sequence of reactions that convert arsenite to methylated metabolites. A scheme linking cyt19 and thioredoxin–thioredoxin reductase in the methylation and reduction of arsenicals is proposed.",
Arsenic,1519025,"Optimal time interval between neoadjuvant chemoradiotherapy and surgery for rectal cancer Abstract: BACKGROUND: Neoadjuvant chemoradiotherapy (CRT) has been proven to increase local control in rectal cancer, but the optimal interval between CRT and surgery is still unclear. The purpose of this study was to analyse the influence of variations in clinical practice regarding timing of surgery on pathological response at a population level. METHODS: All evaluable patients who underwent preoperative CRT for rectal cancer between 2009 and 2011 were selected from the Dutch Surgical Colorectal Audit. The interval between radiotherapy and surgery was calculated from the start of radiotherapy. The primary endpoint was pathological complete response (pCR; pathological status after chemoradiotherapy (yp) T0?N0). RESULTS: A total of 1593 patients were included. The median interval between radiotherapy and surgery was 14 (range 6-85, interquartile range 12-16) weeks. Outcome measures were calculated for intervals of less than 13?weeks (312 patients), 13-14?weeks (511 patients), 15-16?weeks (406 patients) and more than 16?weeks (364 patients). Age, tumour location and R0 resection rate were distributed equally between the four groups; significant differences were found for clinical tumour category (cT4: 17·3, 18·4, 24·5 and 26·6 per cent respectively; P?=?0·010) and clinical metastasis category (cM1: 4·4, 4·8, 8·9 and 14·9 per cent respectively; P?&lt;?0·001). Resection 15-16?weeks after the start of CRT resulted in the highest pCR rate (18·0 per cent; P?=?0·013), with an independent association (hazard ratio 1·63, 95 per cent confidence interval 1·20 to 2·23). Results for secondary endpoints in the group with an interval of 15-16?weeks were: tumour downstaging, 55·2 per cent (P?=?0·165); nodal downstaging, 58·6 per cent (P?=?0·036); and (near)-complete response, 23·2 per cent (P?=?0·124). CONCLUSION: Delaying surgery until the 15th or 16th week after the start of CRT (10-11?weeks from the end of CRT) seemed to result in the highest chance of a pCR.",
Arsenic,656894,"Antioxidant potential of tea reduces arsenite induced oxidative stress in Swiss albino mice Abstract: Environmental arsenic (As) is a potent human carcinogen and groundwater As contamination is a major health concern in West Bengal, India. Oxidative stress has been one of the prime factors in As-induced carcinogenicity. Generation of reactive oxygen species (ROS), beyond the body's endogenous antioxidant balance cause a severe imbalance of the cellular antioxidant defence mechanism. Tea, a popular beverage has excellent chemopreventive and antioxidant properties. In this study it was investigated whether these flavonoids could ameliorate the arsenite (As III) induced oxidative stress in Swiss albino mice. Bio-monitoring with comet assay elicited that the increase in genotoxicity caused by As III was counteracted by both black tea and green tea. Elevated levels of lipid peroxides and protein carbonyl by As III were effectively reduced with green as well as black tea. They also exhibited protective action against the As III induced depletion of antioxidants like catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and glutathione (GSH) in mice liver tissue. Thus the tea polyphenols by virtue of their antioxidant potential may be used as an effective agent to reduce the As III induced oxidative stress in Swiss albino mice.",
Arsenic,2088357,Heat stress and sudden infant death syndrome-Stress gene expression after exposure to moderate heat stress Abstract: ,
Arsenic,1338854,"Agglomerates of aberrant DNA methylation are associated with toxicant-induced malignant transformation Abstract: Epigenetic dysfunction is a known contributor in carcinogenesis, and is emerging as a mechanism involved in toxicant-induced malignant transformation for environmental carcinogens such as arsenicals or cadmium. In addition to aberrant DNA methylation of single genes, another manifestation of epigenetic dysfunction in cancer is agglomerative DNA methylation, which can participate in long-range epigenetic silencing that targets many neighboring genes and has been shown to occur in several types of clinical cancers. Using in vitro model systems of toxicant-induced malignant transformation, we found hundreds of aberrant DNA methylation events that emerge during malignant transformation, some of which occur in an agglomerative fashion. In an arsenite-transformed prostate epithelial cell line, the protocadherin (PCDH), HOXC and HOXD gene family clusters are targeted for agglomerative DNA methylation. The agglomerative DNA methylation changes induced by arsenicals appear to be common and clinically relevant events, since they occur in other human cancer cell lines and models of malignant transformation, as well as clinical cancer specimens. Aberrant DNA methylation in general occurred more often within histone H3 lysine-27 trimethylation stem cell domains. We found a striking association between enrichment of histone H3 lysine-9 trimethylation stem cell domains and toxicant-induced agglomerative DNA methylation, suggesting these epigenetic modifications may become aberrantly linked during malignant transformation. In summary, we found an association between toxicant-induced malignant transformation and agglomerative DNA methylation, which lends further support to the hypothesis that epigenetic dysfunction plays an important role in toxicant-induced malignant transformation.",
Arsenic,1021749,"The enhancing effect of the antioxidant N-acetylcysteine on urinary bladder injury induced by dimethylarsinic acid Abstract: Dimethylarsinic acid (DMA(V)), the major excreted metabolite of inorganic arsenic, is carcinogenic to the rat urinary bladder. Oxidative stress has been proposed as one possible mechanism of DMA(V)-induced carcinogenesis. The authors determined whether the antioxidant N-acetylcysteine (NAC) modifies DMA(V)-induced urinary bladder injury in rats. The treatment solutions--DMA(V) at 10 mg/kg, NAC at 90 or 1.6 mg/kg (high or low dose, respectively), and their combination--were intravesically instilled into female F344 rats over two hours under pentobarbital anesthesia. The treatment was conducted twice with an interval of three days. All animals were euthanized one day after the second treatment. NAC (low dose) alone did not induce histopathological changes or increase 5-bromo-2'-deoxyuridine (BrdU) labeling index in urothelial cells. Both DMA(V) and NAC (high dose) induced a weak neutrophil infiltration and an increase in the BrdU labeling index; these pathological changes were enhanced by the combined treatment of DMA(V) and NAC (high or low dose). Increased oxidative stress and urothelial cell hyperplasia with evidence of activated p44/42 MAPK (ERK1/2) and cyclin D1 were found in the DMA(V) and NAC (high dose) cotreated group. These results suggest that cotreatment with NAC enhanced DMA(V)-induced urinary bladder injury and that the effects may be mediated by excess oxidative stress and ERK signaling.",
Arsenic,1032283,"Reversal of gallium arsenide-induced suppression of the antibody response by a mixed disulfide metabolite of meso-2,3-dimercaptosuccinic acid Abstract: Meso-2,3-dimercaptosuccinic acid (DMSA) has been demonstrated to be an effective chelator of lead, mercury and arsenic in humans and in rodent experiments. Studies involving cadmium exposure have typically shown DMSA to be less effective than 2,3-dimercapto-1-propanesulfonic acid, and this is possibly due to an inability of DMSA to cross cell membranes and bind intracellularly-bound metal ions. The present studies were designed to determine whether in vitro addition of DMSA could effectively reverse arsenic-induced immunosuppression in splenocytes exposed in vivo to gallium arsenide (GaAs; 200 mg/kg, intratracheally). In those investigations, DMSA (25-100 ?M) was incapable of reversing suppression of the in vitro-generated antibody response induced by in vivo exposure to GaAs. Addition of the recently synthesized 2:1 mixed disulfide (L-cysteine-DMSA) metabolite of DMSA (0.1-100 ?M) to cultures of splenocytes exposed in vitro to GaAs (50 ?M) dose-dependently reversed GaAs-induced suppression of the antibody-forming cell response with no effect on the vehicle (complete media) response or on cell viability, indicating that the metabolite retained binding capacity. Unlike DMSA, however, addition of the 2:1 mixed disulfide metabolite to splenocyte cultures exposed in vivo to vehicle (0.05% Tween 80 in saline) or GaAs dose-dependently partially reversed GaAs-induced suppression. The reversal of suppression could not be attributed to cleavage of L-cysteine from the 2:1 mixed disulfide metabolite, as addition of equimolar concentrations of L-cysteine or L-cystine (0.2-200 ?M) to in vitro generated antibody cultures of splenocytes exposed in vivo to vehicle or GaAs had no effect on the GaAs-induced suppression.",
Arsenic,67665,"Evidence for oxidative damage to red blood cells in mice induced by arsine gas Abstract: In animals and human beings exposed to arsine gas (AsH3) a severe and fulminant lysis of erythrocytes occurs. Little is known about the effects of subchronic exposure on the hematopoietic system or about the mechanism of hemolysis produced by arsine gas. To examine these, we exposed male and female mice to 0.000, 0.025, 0.500 and 2.500 ppm arsine gas for 6 h a day, 5 days a week during a 90-day period. After 5, 15, and 90 days of exposure, blood was collected and routine hematologic profiles were performed to document the effects of arsine gas on peripheral blood. A moderate hemolytic anemia, indicated by decreases in erythrocyte counts, hematocrits, hemoglobin concentrations and increases in mean corpuscular hemoglobins and mean corpuscular hemoglobin concentrations, was seen in blood samples collected after 5 days of exposure. In blood collected after 15 and 90 days of exposure, the anemia was less severe but a greater increase in mean corpuscular volumes and absolute reticulocyte counts revealed an active regenerative response. Higher concentrations of methemoglobin in animals in the 2.500 ppm exposure group (measured after 90 days of exposure) indicated that the rate of oxidation of heme (ferrous to ferric) increased due to exposure to arsine gas. Additionally, the presence of Heinz bodies in blood smears stained with brilliant cresyl blue and decreases in reduced glutathione concentrations in red blood cells exposed to arsine gas in vitro provide evidence that the mechanism of hemolysis involves depletion of intracellular reduced glutathione resulting in an oxidation of sulfhydryl groups in hemoglobin and possibly red cell membranes.",
Arsenic,840297,"Regulation of NO from endothelial cells by the decrease of cellular cAMP under arsenite exposure Abstract: In an attempt to delineate the direct effect of arsenite-induced endothelial dysfunction on nitric oxide (NO) production, confluent bovine aortic endothelial cells (BAEC) were incubated with arsenite, and endothelial NO synthase expression and NO production were measured. Exposure of arsenite decreased NO production for up to 24 h. This decrease was accompanied by decreases in cAMP, protein kinase A (PKA) activity, and furthermore, significant reduction of pCREB. In conclusion, this study is the first to demonstrate that exposure of arsenite decreases NO production by a reduction of pCREB and PKA activity that may be mediated by cAMP, leading to endothelial dysfunction.",
Arsenic,1352072,Genes related to lung growth and mucociliary function are altered by in utero exposure to arsenic via drinking water Abstract: ,
Arsenic,1024599,"Characterization of a symbiotically effective Rhizobium resistant to arsenic: Isolated from the root nodules of Vigna mungo (L.) Hepper grown in an arsenic-contaminated field Abstract: Bacteria were isolated from the root nodules of Vigna mungo (L.) Hepper, grown in an arsenic-contaminated field and the strain was selected by its nodulation ability as well as better arsenic tolerant capacity compared to others. The selected strain was identified as Rhizobium by 16S rDNA sequencing and designated as VMA301. Phylogenetic analysis of the gene sequences showed its close relatedness with Sinorhizobium fredii. LC(50) value of arsenate for the bacteria as determined by flow cytometry was found to be 2.8 mM and arsenic uptake was measured by atomic absorption spectrometry as 0.048 mg g(-1) biomass. The high amount of arsenic was toxic to the cell, which changed the morphology of the bacteria to an elongated shape. Presence of a transcriptional regulatory gene (ArsR) of the ars genetic system was confirmed by amplification and sequencing. The symbiotic property of the isolate was also confirmed by amplification and sequencing of the NodC gene. These results indicate that the isolated Rhizobium bacteria may exert dual roles in the environment, arsenic bioremediation from the soil as well as increase of soil fertility through nitrogen fixation.",
Arsenic,2337283,"A simple spectrophotometric method for the determination of arsenic in industrial and environmental samples using 2,4-dihydroxy benzophenone-2-amino thiophenol Abstract: 2,4-Dihydroxy benzophenone-2-amino thiophenol (BPBT) has been proposed as new analytical reagent for the direct non-extractive spectrophotometric determination of arsenic. The reagent reacts with arsenic in acidic medium (pH=6.0, sodium acetate-acetic acid buffer) to form light greenish yellow colored 1:1 (M:L) complex. Maximum absorbance was obtained at 343 nm and remains constant for over 24 h. The molar absorptivity and Sandell's sensitivity of BPBT are found to be 6.01×10(4) L mol(-1)cm(-1) and 0.0016 ?g cm(-2) respectively. The system obeys Beer's law in the range of 0.125-2.637 ?g/ml of As (III). Since BPBT method is more sensitive, it was applied for the determination of arsenic in some environmental water samples.",
Arsenic,627220,"Long-term exposure to arsenic affects head kidney and impairs humoral immune responses of Clarias batrachus Abstract: The present study was aimed at determining the effects of long-term arsenic exposure on the head kidney (HK) and ensuing humoral immune responses in Clarias batrachus L. Long-term exposure (150 days) to non-lethal concentrations of arsenic (42.42 microM) resulted in significant time-dependent alterations in HK cell number eventually affecting the HK somatic index. Prolonged exposure to arsenic also suppressed HK-B cell proliferation and led to significant reduction in serum immunoglobulin levels and antigen-specific serum bacterial agglutinin titers. A decline in the number of antigen-specific plaque-forming cells with duration of arsenic exposure was noted in the HK. Enzyme linked immunosorbent assays further revealed that arsenic exposure inhibited the release of ""IL-4 like factors"" from HK-T cells. Histological studies documented time-dependent changes in the structure and cellular composition of HK characterized by extensive lymphocytopenia, decrease in melano-macrophage population and hemosiderin accumulation. From exposure-challenge studies with Aeromonas hydrophila it was evident that pathogens could efficiently disseminate and colonize distant host tissues in the exposed fish. Moreover, the ability to decrease the pathogen load was also significantly reduced in the arsenic-exposed fish. Thus long-term exposure to non-lethal concentrations of arsenic affects HK and interferes with the humoral immune system of C. batrachus rendering them immunocompromised and susceptible to pathogenic challenge.",
Arsenic,1029559,"Two-dimensional quantitative mapping of arsenic in nanometer-scale silicon devices using STEM EELS-EDX spectroscopy Abstract: Field emission gun (FEG) nanoprobe scanning electron transmission microscopy (STEM) techniques coupled with energy dispersive X-ray (EDX) and electron energy loss spectroscopy (EELS) are evaluated for the detection of the n-type dopant arsenic, in silicon semiconductor devices with nanometer-scale. Optimization of the experimental procedure, data extraction and the signal-to-noise ratio versus electron dose, show that arsenic detection below 0.1% should be possible. STEM EDX and EELS spectrum profiles have been quantified and compared with secondary ion mass spectrometry (SIMS) analyses which show a good agreement. In addition, the arsenic doping level found inside large and small epitaxial devices have been compared using STEM EDX-EELS profiling. The average doping level is found to be similar but variable interface segregation has been observed. Finally, STEM EDX arsenic mapping acquired in a BiCMOS transistor cross-section shows strong heterogeneities and segregation in the epitaxially grown emitter part.",
Arsenic,628360,"Likelihood ratio analysis of skin cancer prevalence associated with arsenic in drinking water in the USA Abstract: Several published studies have examined skin-cancer prevalence in regions of the USA that have concentrations of arsenic above the USA drinking-water standard. Those studies with adequate exposure and health outcome data did not report any skin cancer cases. Because the USA's arsenic concentrations are relatively low compared to some other countries and the study populations are small, the absence of reported skin-cancer cases could be due to an absence of risk in USA populations or random variability from a predicted risk. We used the current EPA arsenic cancer slope factor (CSF) model, which is derived from Taiwanese populations exposed to high levels of arsenic, to predict the expected number of skin cancers. We then conducted a likelihood ratio analysis, which showed that a null hypothesis (no additional skin cancer risk from arsenic) was approximately 2.2 times more likely than the hypothesis that ingested arsenic causes the predicted rate of skin cancers. Although based on small numbers, our analysis of USA populations indicates that the CSF derived from arsenic exposure in Taiwanese populations may be an overestimate when applied to USA populations.",
Arsenic,1022235,"Arsenic groundwater contamination in Middle Ganga Plain, Bihar, India: A future danger? Abstract: The pandemic of arsenic poisoning due to contaminated groundwater in West Bengal, India, and all of Bangladesh has been thought to be limited to the Ganges Delta (the Lower Ganga Plain), despite early survey reports of arsenic contamination in groundwater in the Union Territory of Chandigarh and its surroundings in the northwestern Upper Ganga Plain and recent findings in the Terai area of Nepal. Anecdotal reports of arsenical skin lesions in villagers led us to evaluate arsenic exposure and sequelae in the Semria Ojha Patti village in the Middle Ganga Plain, Bihar, where tube wells replaced dug wells about 20 years ago. Analyses of the arsenic content of 206 tube wells (95% of the total) showed that 56.8% exceeded arsenic concentrations of 50 micro g/L, with 19.9% > 300 micro g/L, the concentration predicting overt arsenical skin lesions. On medical examination of a self-selected sample of 550 (390 adults and 160 children), 13% of the adults and 6.3% of the children had typical skin lesions, an unusually high involvement for children, except in extreme exposures combined with malnutrition. The urine, hair, and nail concentrations of arsenic correlated significantly (r = 0.72-0.77) with drinking water arsenic concentrations up to 1,654 micro g/L. On neurologic examination, arsenic-typical neuropathy was diagnosed in 63% of the adults, a prevalence previously seen only in severe, subacute exposures. We also observed an apparent increase in fetal loss and premature delivery in the women with the highest concentrations of arsenic in their drinking water. The possibility of contaminated groundwater at other sites in the Middle and Upper Ganga Plain merits investigation.",
Arsenic,1453793,"Effects of arsenic trioxide (As(2)O(3)) on airway remodeling in a murine model of bronchial asthma Abstract: We investigated the effects of arsenic trioxide (As(2)O(3)) as a possible approach for preventing airway remodeling in a murine model of bronchial asthma induced by ovalbumin (OVA) challenge. Forty Balb/c mice were randomly assigned to 1 of 4 groups (10 mice/group) as follows: controls (challenged with sterile saline inhalation only); OVA-challenged, no treatment; OVA-challenged, treated with dexamethasone; and OVA-challenged, treated with As(2)O(3). All mice were sensitized by intraperitoneal injection with 10% OVA at 2 weeks prior to saline or OVA inhalation challenge. Challenges were for 8 weeks. After OVA challenge, typical asthma-like morphology changes in the bronchi and lung tissues were observed by hematoxylin-eosin staining and pulmonary function indices were reduced compared with controls. Changes in pulmonary indices and lung tissues were similar in the dexamethasone and As(2)O(3) groups and were in between those of the untreated and control groups. Compared with the untreated group, transforming growth factor ?1, vascular endothelial growth factor, and matrix metalloproteinase-9 protein levels and mRNA expression were decreased in lung tissues of the dexamethasone and As(2)O(3) groups. Our results suggest that steroids and As(2)O(3) can inhibit airway remodeling in chronic asthma by mechanisms related to inhibiting the expression of the 3 aforementioned mediators.",
Arsenic,1240148,"Arsenic removal from water by iron-modified bamboo charcoal Abstract: The effectiveness of a novel and low-cost adsorbent, iron-modified bamboo charcoal (BC-Fe), for arsenic removal from aqueous systems was evaluated in this study. The BC-Fe was synthesized by loading iron onto bamboo charcoal via soaking in a ferric salt solution. The BC-Fe possessed a porous structure with a surface area of 277.895 m super(2)/g. The adsorption characteristics of arsenic onto BC-Fe were further investigated at various pHs, contact times, arsenic concentrations, and adsorbent doses in batch tests. The corresponding optimum equilibrium pH ranges for As(III) and As(V) removal were 4-5 and 3-4, respectively. The equilibrium times for As(III) and As(V) adsorption were 30 and 35.5 h, respectively. The arsenic removal was strongly dependent on the initial adsorbate concentration and adsorbent dosage. The maximum arsenic removal capacities of BC-Fe under the experimental conditions were 7.237 and 19.771 mg/g for As(III) and As(V), respectively. The pseudo-second-order kinetic model and Freundlich isotherm explained the kinetic and equilibrium of both the As(III) and As(V) adsorbent processes, respectively. Based on these results, the BC-Fe developed in this study is a promising material for the treatment of arsenic-contaminated water.",
Arsenic,8326,Renal mechanism for excretion and transformation of arsenic in the dog Abstract: Studies are performed in female dogs on the renal tubular transport of arsenate and arsenite and on the intrarenal conversion of arsenate to arsenite. The rate of arsenite secretion is found to vary directly with the rate of arsenate reabsorption. The transport of both ions is inhibited by phosphate and glucose. Renal arteriovenous concentration differences show a net production of arsenite from arsenate. Stop flow studies localize the major site of arsenic (7440382) transport in the proximal tubule. During arsenite infusion both arsenate and arsenite undergo net reabsorption of arsenate with intracellular conversion of arsenate to arsenite and subsequent diffusion of arsenite across both luminal and antiluminal faces of the tubular cell.,
Arsenic,1018436,"Influence of maternal stress on the effects of prenatal exposure to methylmercury and arsenic on postnatal development and behavior in mice: A preliminary evaluation Abstract: The present study combined maternal restraint stress with exposure to 2 environmental toxic elements, mercury and arsenic, given to mice concurrently with the restraint period (1000-1200 h, gestational days 15-18). Two groups of animals were given, by gavage, methylmercury chloride (MMC) (2 mg/kg/day), and 2 additional groups received sodium arsenite (10 mg/kg/day) on days 15-18 of gestation. Immediately after MMC or arsenite exposure, 1 group of MMC-treated mice and 1 group of arsenite-treated animals were restrained for 2 h/day. Control groups included restrained and unrestrained pregnant mice nonexposed to MMC or arsenite. All animals were allowed to deliver and wean their offspring. Pups were evaluated for physical development, as well as for behavioral effects. Except for a significant decrease in pivoting on postnatal day 9 in the group exposed to arsenite plus restraint, no other MMC- or arsenite-induced behavioral changes were noted in unrestrained or restrained groups. Although a significant delay in pinna detachment and in eye opening was observed in pups of the group exposed to arsenite and restraint, the development landmarks were not affected by restraint in the MMC-treated animals. Although maternal stress reduced body weight gain in the dams exposed to MMC plus restraint, a significant interaction between maternal stress and MMC could not be established for developmental toxicity. These preliminary results, combined with those of previous investigations, show that stress can significantly exacerbate the adverse effects of environmental toxic elements.",
Arsenic,627268,"Arsenite enhances DNA double-strand breaks and cell killing of methyl methanesulfonate-treated cells by inhibiting the excision of alkali-labile sites Abstract: Analysis of DNA strand breaks by alkaline elution indicates that DNA repair of Chinese hamster ovary cells treated with methyl methanesulfonate (MMS) was inhibited by sodium arsenite. Comparing the profiles of a 36-min elution with buffer pH 12.1 and a 12-h elution with buffer pH 12.4 revealed that alkali-labile sites were increased more than frank breaks in the combined treatment with MMS plus arsenite. Enhancement of alkali-labile sites was detected with low doses of MMS and arsenite, whereas enhancement of frank breaks required higher doses of MMS and arsenite. Double-strand breaks were detected after incubating the MMS-treated cells in an arsenite-containing medium for 18 or 12 h but not less than 6 h. No double-strand breaks were detected when MMS-damaged cells were posttreated with arsenite for 3 h; however, double-strand breaks were detected after further incubating these cells in arsenite-free medium for 18 h. Thus, inhibition of arsenite on the excision of methylated bases may have accumulated a large number of alkali-labile sites in the parental strands, and DNA replication may then generate breaks in the non-methylated daughter strands. Double-strand breaks may result from overlapping gaps between the parental and daughter strands and/or postreplication repair. These double-strand breaks may then result in the synergistic cell death as observed with posttreatment of MMS-damaged cells with arsenite for 1 or 3 h.",
Arsenic,1352807,"CYTOKINES AND GROWTH-FACTORS INDUCE HSP27 PHOSPHORYLATION IN HUMAN ASTROCYTES Abstract: In previous studies, an enhanced expression with abnormal phosphorylation of a low molecular weight heat shock protein, HSP27, was identified in reactive astrocytes and Rosenthal fibers in Alexander disease brain. To investigate the relevance of HSP27 to the pathological change of astrocytes, phosphorylation of HSP27 was examined in astrocyte cultures isolated from fetal human brains. In unstimulated human astrocytes, HSP27 was identified in the cytoplasm and was comprised of a major unphosphorylated &quot;a&quot; isoform and a minor monophosphorylated &quot;b&quot; isoform. The level of HSP27 phosphorylation was elevated greatly after a 30 minute exposure to heat shock, sodium arsenite, interleukin-1 (IL-1 alpha and IL-1 beta), and tumor necrosis factor-alpha (TNF-alpha) with an increased expression of a diphosphorylated &quot;c&quot; isoform. Treatment with interferon-beta (IFN-beta), platelet-derived growth factor-AA, leukemia inhibitory factor, phorbol 12-myristate 13-acetate, and dibutyryl cyclic AMP stimulated phosphorylation of HSP27 moderately, while IFN-gamma, TNF-beta, basic fibroblast growth factor, epidermal growth factor, or fetal bovine serum did not significantly alter the level of HSP27 phosphorylation. Total amount of the HSP27 protein and its cytoplasmic localization were unaffected by any of these reagents. These results indicate that HSP27 is a constitutive protein in human astrocytes. The induction of HSP27 phosphorylation by a specific set of cytokines and growth factors suggests that HSP27 is a key cellular substrate by which signaling events are mediated in human astrocytes under normal and pathological conditions.",
Arsenic,2298678,"Effects of phosphate and thiosulphate on arsenic accumulation in the species Brassica juncea Abstract: Arsenic (As) is recognized as a toxic pollutant in soils of many countries. Since phosphorus (P) and sulphur (S) can influence arsenic mobility and bioavailability, as well as the plant tolerance to As, phytoremediation techniques employed to clean-up As-contaminated areas should consider the interaction between As and these two nutrients. In this study, the bioavailability and accumulation of arsenate in the species Brassica juncea were compared between soil system and hydroponics in relation to P and S concentration of the growth substrate. In one case, plants were grown in pots filled with soil containing 878 mg As kg(-1). The addition of P to soil resulted in increased As desorption and significantly higher As accumulation in plants, with no effect on growth. The absence of toxic effects on plants was likely due to high S in soil, which could efficiently mitigate metal toxicity. In the hydroponic experiment, plants were grown with different combinations of As (0 or 100 ?M) and P (56 or 112 ?M). S at 400 ?M was also added to the nutrient solution of control (-As) and As-treated plants, either individually or in combination with P. The addition of P reduced As uptake by plants, while high S resulted in higher As accumulation and lower P content. These results suggest that S can influence the interaction between P and As for the uptake by plants. The combined increase of P and S in the nutrient solution did not lead to higher accumulation of As, but enhanced As translocation from the root to the shoot. This aspect is of relevance for the phytoremediation of As-contaminated sites.",
Arsenic,1239868,"Speciated urinary arsenic as a biomarker of dietary exposure to inorganic arsenic in residents living in high-arsenic areas in Latium, Italy Abstract: Current knowledge indicates that total urinary arsenic is not a suitable biomarker of exposure to toxic, i.e., inorganic, arsenic (iAs), whereas measurement of iAs and its methylated metabolites in urine using speciation analysis provides much more reliable estimates of exposure. The relative proportions of urinary iAs, monomethylarsonate (MA), and dimethylarsinate (DMA) can be used as a measure of methylation capacity, provided that there are no confounding factors such as consumption of food rich in DMA or containing As compounds metabolized to DMA. We analyzed by gradient elution anion-exchange HPLC-ICP-MS (high-performance liquid chromatography-inductively coupled plasma-mass spectrometry) urine samples from 153 residents in Latium (central Italy) chronically exposed to iAs via water and food. Excluding 26 subjects that excreted high concentrations of arsenobetaine (AB) (>= 50 mu g As/L) due to seafood consumption, iAs and related metabolites summed up about 75 % of total urinary As as measured by ICP-MS. AB and other organoarsenic compounds were detected at low concentrations in all urine samples. Considering all subjects, the sum of iAs and metabolites ranged 2-72 mu g/L and relative proportions were iAs 14 %, MA 13 %, and DMA 72 % (median values), with a wide individual variability. In addition to the above arsenocompounds, the analytical method used in this study enabled the detection of dimethylthioarsinic acid (DMTA), which was found to be present in 33 % of the samples at concentrations ranging mostly from trace amounts to similar to 6 mu g As/L. We found that part of the certified DMA content of human urine reference material SRM 2669 was present as DMTA. Four unknown arsenicals were also detected as minor species in a small proportion of samples.",
Arsenic,1070405,"Linking selenium biogeochemistry to the sulfur-dependent biological detoxification of arsenic Abstract: Geochemistry often reveals unexpected (anti)correlations. Arsenic (As) and selenium (Se) are cases in point. We explore the hypothesis that bacteria living in an As-replete environment recruited a biological process involving Se and sulfur to fulfil their need for As detoxification. In analogy with the formation of arsenolipids and arsenosugars, which are common non-toxic As metabolites derived from microbial and plant metabolism, we attempt to explain the prevalence of novel sulfur-containing As derivatives, in particular monothioarsenate, in the aqueous environment. Thiolated-As species have been overlooked so far mainly because of the difficulty of their identification. Based on comparative genomics, we propose a scenario where SelD and SelU proteins, commonly used to make selenophosphate and modify transfer RNA, have been recruited to make monothioarsenate, a relatively innocuous arsenical. This hypothesis is discussed in terms of the relative geochemical distribution of Se and As.",
Arsenic,737288,"Arsenic levels in drinking water and the prevalence of skin lesions in West Bengal, India Abstract: A cross-sectional survey was conducted between April 1995 and March 1996 to investigate arsenic-associated skin lesions of keratosis and hyperpigmentation in West Bengal, India, and to determine their relationship to arsenic water levels.<br /><br /> In all, 7683 participants were examined and interviewed, and the arsenic levels in their drinking water measured.<br /><br /> Although water concentrations ranged up to 3400 microg/l of arsenic, over 80% of participants were consuming water containing <500 microg/l. The age-adjusted prevalence of keratosis was strongly related to water arsenic levels, rising from zero in the lowest exposure level (<50 microg/l) to 8.3 per 100 for females drinking water containing >800 microg/l, and increasing from 0.2 per 100 in the lowest exposure category to 10.7 per 100 for males in the highest exposure level (> or =800 microg/l). However, 12 cases with keratosis (2 females and 10 males) were drinking water containing <100 microg/l of arsenic. Findings were similar for hyperpigmentation, with strong dose-response relationships. Among those with hyperpigmentation, 29 cases were exposed to drinking water containing <100 microg/l. Calculation by dose per body weight showed that men had roughly two to three times the prevalence of both keratosis and hyperpigmentation compared to women apparently ingesting the same dose of arsenic from drinking water. Subjects who were below 80% of the standard body weight for their age and sex had a 1.6 fold increase in the prevalence of keratoses, suggesting that malnutrition may play a small role in increasing susceptibility.<br /><br /> The surprising finding of cases who had arsenic-associated skin lesions with apparently low exposure to arsenic in drinking water needs to be confirmed in studies with more detailed exposure assessment. Further research is also needed concerning susceptibility factors which might be present in the exposed population.",
Arsenic,2337209,"Evaluation of dispersal volcanic products of recent events in lichens in environmental gradient, Nahuel Huapi National Park, Argentina Abstract: The atmospheric transport of volcanic products are subject to several variables, mainly the height of the eruption column and wind direction, thus elements associated with the ashes are deposited in major or lesser degree depending on variables as latitude, wind and humidity. The lichens are able to reflect the atmospheric fallout. The present work evaluated the correlation between meteorological parameters, geographic locations, sulphur and other element concentrations in lichens genus Usnea affected by Puyehue-Cordón Caulle complex (North Patagonia Andean Range) eruption of June 4, 2011. Semiquantitative analyses of biological elements by scanning electron microscope methods, sulphur (S) by LECO and other elements by instrumental neutron activation were evaluated by principal component analysis. Elements as antimony, arsenic, barium, bromine, calcium, caesium, potassium, rubidium, selenium, and uranium correlated with distance to volcano, also calcium and potassium with longitude while bromine, rubidium, and potassium with humidity. Those results indicate that Usnea sp. is a good bioindicator of the atmospheric volcanic emissions in relation to environmental gradient.",
Arsenic,1354748,SPECTROPHOTOMETRIC DETERMINATION OF ARSENIC USING CARRIER GAS PREPARED IN THE HYDRIDE GENERATION CHAMBER Abstract: ,
Arsenic,2149132,"Mitochondrial genome variations among arsenic exposed individuals and potential correlation with apoptotic parameters Abstract: Exposure to arsenic (As) causes serious health hazards. Therefore, there is a sustained effort to understand the molecular basis of the risk posed by the toxicant. It has been reported that apoptotic changes ensue on exposure to As. To investigate the molecular basis of such changes, we sequenced the entire mitochondrial (mt) genome from PBMC of a subset of these individuals (As-exposed=16 and unexposed=18) using Affymetrix platform. Our analysis revealed that As exposure does not induce large-scale mt-DNA variations, but that specific deleterious changes could induce mt dysfunction. A Glu115Ter mutation as well as 17 other in silico predicted deleterious variants were identified exclusively in exposed individuals. The number of variants in mt Complex I in As-exposed individuals was positively correlated with their respective intracellular ROS level. In addition, the extent of potentially damaging variants in As-exposed individuals had significant positive correlation to the degree of G0 /G1 cell cycle arrest. Environ. Mol. Mutagen., 2013. © 2013 Wiley Periodicals, Inc.",
Arsenic,1021546,"Apoptosis of peripheral blood mononuclear cells in children exposed to arsenic and fluoride Abstract: In this study, we evaluated apoptosis induction in human immune cells in children exposed to arsenic (As) and fluoride (F). Children living in two areas in Mexico (Soledad de Graciano Sanchez (SGS) in San Luis Potosí and Colonia 5 de Febrero in Durango) were studied. Water, urine and blood samples were collected. Approximately 90% of the water samples in 5 de Febrero had As and F levels above the World Health Organization intervention guideline (10 ?g/L and 1.5mg/L, respectively). In SGS, 0% of the water samples exceeded Mexican guidelines. Urinary As and F levels in children living in 5 de Febrero were significantly higher than the levels found in children living in SGS. In addition, the level of apoptosis was higher in children from the 5 de Febrero community when compared with the level of apoptosis in children living in SGS. Thus, in a worldwide context, our study demonstrates the health risks to children living in these regions.",
Arsenic,1519048,"Pancreatic cancer clusters and arsenic-contaminated drinking water wells in Florida Abstract: <strong>BACKGROUND: </strong>We sought to identify high-risk areas of pancreatic cancer incidence, and determine if clusters of persons diagnosed with pancreatic cancer were more likely to be located near arsenic-contaminated drinking water wells.<br /><br /><strong>METHODS: </strong>A total of 5,707 arsenic samples were collected from December 2000 to May 2008 by the Florida Department of Health, representing more than 5,000 individual privately owned wells. During that period, 0.010 ppm (10 ppb) or greater arsenic levels in private well water were considered as the threshold based on standard of United States Environmental Protection Agency (EPA). Spatial modeling was applied to pancreatic cancer cases diagnosed between 1998-2002 in Florida (n?=?11,405). Multivariable logistic regression was used to determine if sociodemographic indicators, smoking history, and proximity to arsenic-contaminated well sites were associated with residence at the time of pancreatic cancer diagnosis occurring within versus outside a cluster.<br /><br /><strong>RESULTS: </strong>Spatial modeling identified 16 clusters in which 22.6% of all pancreatic cancer cases were located. Cases living within 1 mile of known arsenic-contaminated wells were significantly more likely to be diagnosed within a cluster of pancreatic cancers relative to cases living more than 3 miles from known sites (odds ratio?=?2.1 [95% CI?=?1.9, 2.4]).<br /><br /><strong>CONCLUSIONS: </strong>Exposure to arsenic-contaminated drinking water wells may be associated with an increased risk of pancreatic cancer. However, case-control studies are needed in order to confirm the findings of this ecological analysis. These cluster areas may be appropriate to evaluate pancreatic cancer risk factors, and to perform targeted screening and prevention studies.",
Arsenic,2088370,"Arsenic removal from water using industrial by-products Abstract: In this study, removal of arsenic ions using two industrial by-products as adsorbents is represented. Removal of As(III) and As(V) from water was carried out with industrial by-products: residual from the groundwater treatment process, iron-manganese oxide coated sand (IMOCS), and blast furnace slag from steel production (BFS), both inexpensive and locally available. In addition, the BFS was modified in order to minimise its deteriorating impact on the initial water quality. Kinetic and equilibrium studies were carried out using batch and fixed-bed column adsorption techniques under the conditions that are likely to occur in real water treatment systems. To evaluate the application for real groundwater treatment, the capacities of the selected materials were further compared to those exhibited by commercial sorbents, which were examined under the same experimental conditions. IMOCS was found to be a good and inexpensive sorbent for arsenic, while BFS and modified slag showed the highest affinity towards arsenic. All examined waste materials exhibited better sorption performances for As(V). The maximum sorption capacity in the batch reactor was obtained for blast furnace slag, 4040??gAs(V)/g.",
Arsenic,2149285,Nanofiltration of Acid Mine Drainage in an Abandoned Mercury Mining Area Abstract: ,
Arsenic,656949,"Effects of cysteine on the cytotoxicity of arsenic compounds Abstract: Effects of cysteine on the cytotoxicity of arsenic compounds, such as arsenite, arsenate, methylarsonic acid (MMA), and dimethylarsinic acid (DMA), were investigated in cultured human HL-60 cells. Using adenosine triphosphate bioluminescence assay, the rank order of the mixtures of arsenicals with cysteine was: DMA > arsenite > arsenate > MMA. The IC50 of DMA with equimolar cysteine was approximately 7.7 mgrM, nearly two orders of magnitude lower than that of DMA alone. Apoptotic cells were examined by the TUNEL method, and cysteine was found to enhance the induction of apoptosis by arsenicals. Using LC-ICP-MS, trivalent arsenic was detected in the mixtures of arsenate, DMA, and MMA with cysteine. These results suggested that the trivalent arsenic in the mixtures of arsenicals with cysteine might account for the enhanced cytotoxicity as well as apoptosis, and that cysteine is involved in induction of the adverse effects of arsenicals in humans.",
Arsenic,627213,"Role of oxidative stress in arsenic-induced toxicity Abstract: Arsenic is recognized as a carcinogen for human skin, bladder, and lung, following either ingestion or inhalation; however the exact mode of action of environmentally relevant exposure has not been determined. Because arsenic in the environment exists in several oxidative states and can interact with thiols, it is thought that arsenic toxicity is mediated through oxidative stress. Production of oxygen radicals following acute in vitro exposures has been demonstrated. However, our research has chosen to focus on the role of oxidative stress following whole animal exposure to environmentally relevant doses of arsenic. Following a 28-d inhalation of arsenic or cigarette smoke or both, there was a significant decrease in both the reduced and total glutathione levels in the combined arsenic and smoke group compared to groups exposed to arsenic or smoke alone. This correlated with a 5-fold increase in DNA oxidation. Lungs processed for immunohistochemistry localization of 8-oxo-dG showed increased staining in nuclei of airway epithelium and subadjacent interstitial cells. Increases in DNA oxidation were not due to increased inflammation. Although inhalation of arsenic is an important occupational exposure, the majority of human exposures occurs through ingestion of arsenic. Our recent work has been devoted to the identification of altered pulmonary gene and protein expression following ingestion of environmentally relevant levels of arsenic in drinking water. We have found that, following chronic exposure, arsenic leads to misregulation of a number of genes and proteins in the lung. A large percentage of the altered genes and proteins are known to be regulated by redox-sensitive transcription factors, (SP1, NF kappaB, AP-1), suggesting that, at environmentally relevant levels of chronic exposure, arsenic may be acting through alteration of cellular redox status. Validation of the alterations seen in animal models of exposure is being carried out in humans.",
Arsenic,1034562,"Some aspects of the environmental exposure to arsenic in Romania Abstract: The main sources of arsenic emission in Romania are ore smelters and refineries. Arsenic determinations were carried out by the silver diethyldithiocarbamate spectrophotometric method on hair and urine samples taken from smelter workers and individuals residing in two polluted areas and three areas not polluted by arsenic. Arsenic in hair was found to be a more reliable biologic test than tests on urine, obviously reflecting the differences in arsenic concentrations in workroom air. Repeated determinations for arsenic content after 3 years revealed a twofold increased rate in the 48 re-examined workers. Hair arsenic analysis in people living in two locations near an ore smelter and a refinery indicated high-levels compared to those of individuals residing in nonpolluted areas. Epidemiological studies are necessary in order to ascertain effects of heavy arsenic exposure in relation with concurrent exposures to respiratory irritants and metals.",
Arsenic,736234,"Chronic arsenic exposure and cardiac repolarization abnormalities with QT interval prolongation in a population-based study Abstract: Chronic arsenic exposure is associated with cardiovascular abnormalities. Prolongation of the QT (time between initial deflection of QRS complex to the end of T wave) interval and profound repolarization changes on electrocardiogram (ECG) have been reported in patients with acute promyelocytic leukemia treated with arsenic trioxide. This acquired form of long QT syndrome can result in life-threatening arrhythmias.<br /><br /> The objective of this study was to assess the cardiac effects of arsenic by investigating QT interval alterations in a human population chronically exposed to arsenic.<br /><br /> Residents in Ba Men, Inner Mongolia, have been chronically exposed to arsenic via consumption of water from artesian wells. A total of 313 Ba Men residents with the mean arsenic exposure of 15 years were divided into three arsenic exposure groups: low (&lt; or = 21 microg/L), medium (100-300 microg/L), and high (430-690 microg/L). ECGs were obtained on all study subjects. The normal range for QTc (corrected QT) interval is 0.33-0.44 sec, and QTc &gt; or = 0.45 sec was considered to be prolonged.<br /><br /> The prevalence rates of QT prolongation and water arsenic concentrations showed a dose-dependent relationship (p = 0.001). The prevalence rates of QTc prolongation were 3.9, 11.1, 20.6% for low, medium, and high arsenic exposure, respectively. QTc prolongation was also associated with sex (p &lt; 0.0001) but not age (p = 0.486) or smoking (p = 0.1018). Females were more susceptible to QT prolongation than males.<br /><br /> We found significant association between chronic arsenic exposure and QT interval prolongation in a human population. QT interval may potentially be useful in the detection of early cardiac arsenic toxicity.",
Arsenic,1936084,"Human Ntera2 cells as a predictive in vitro test system for developmental neurotoxicity Abstract: Developmental neurotoxicity (DNT) of environmental chemicals is a serious threat to human health. Current DNT testing guidelines propose investigations in rodents, which require large numbers of animals. With regard to the &quot;3Rs&quot; (reduction, replacement, and refinement) of animal testing, alternative testing strategies are needed in order to refine and reduce animal experiments and allow faster and less expensive screening. The goal of this study was to establish components for a human cell-based test system to assess DNT potential of chemicals at an early stage of brain development. A human neural precursor cell line should be tested for suitability for semi-automated high-throughput DNT screening. We established assays suitable for detecting disturbances in two basic processes of brain development in 96-well scale: neuronal differentiation and migration using the human Ntera2 (NT2) cell line. We assessed the effects of four test compounds with well-established DNT potential in comparison with three compounds without specific DNT potential. We found that human NT2 cell cultures treated with the morphogen, retinoic acid, imitate neuronal differentiation, and migration in vitro. The developmental neurotoxicants methylmercury chloride, sodium arsenite, sodium valproate, and methylazoxymethanol significantly reduced the expression of the neuronal marker ?-tubulin type III and decreased the migration distance in developing NT2 cells. Both endpoints, differentiation and migration, can be read out directly in a standard fluorescence plate reader, enabling high-throughput screening. We conclude that NT2 cell tests are likely to become valuable components of a human cell-based modular in vitro DNT test systems.",
Arsenic,1021472,"Polymorphic trial in oxidative damage of arsenic exposed Vietnamese Abstract: Arsenic causes DNA damage and changes the cellular capacity for DNA repair. Genes in the base excision repair (BER) pathway influence the generation and repair of oxidative lesions. Single nucleotide polymorphisms (SNPs) in human 8-oxoguanine DNA glycosylase (hOGG1) Ser326Cys; apurinic/apyrimidinic endonuclease (APE1) Asp148Glu; X-ray and repair and cross-complementing group 1 (XRCC1) Arg280His and Arg399Gln in the BER genes were analyzed, and the relationship between these 4 SNPs and the urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations of 100 Vietnamese population exposed to arsenic was investigated. Individuals with hOGG1 326Cys/Cys showed significantly higher urinary 8-OHdG concentrations than did those with 326 Ser/Cys and Ser/Ser. As for APE1 Asp148Glu, heterozygous subjects showed significantly higher urinary 8-OHdG concentrations than did those homozygous for Asp/Asp. Moreover, global ethnic comparison of the allelic frequencies of the 4SNPs was performed in 10 population and previous reported data. The mutant allele frequencies of hOGG1 Ser326Cys in the Asian populations were higher than those in the African and Caucasian populations. As for APE1 Asp148Glu, Caucasians showed higher mutant frequencies than those shown by African and Asian populations. Among Asian populations, the Bangladeshi population showed relatively higher mutant allele frequencies of the APE1 Asp148Glu polymorphism. This study is the first to demonstrate the existence of genetic heterogeneity in a worldwide distribution of SNPs (hOGG1 Ser326Cys, APE1 Asp148Glu, XRCC1 Arg280His, and XRCC1 Arg399Gln) in the BER genes.",
Arsenic,1337282,"Assessing the microbial community and functional genes in a vertical soil profile with long-term arsenic contamination Abstract: Arsenic (As) contamination in soil and groundwater has become a serious problem to public health. To examine how microbial communities and functional genes respond to long-term arsenic contamination in vertical soil profile, soil samples were collected from the surface to the depth of 4 m (with an interval of 1 m) after 16-year arsenic downward infiltration. Integrating BioLog and functional gene microarray (GeoChip 3.0) technologies, we showed that microbial metabolic potential and diversity substantially decreased, and community structure was markedly distinct along the depth. Variations in microbial community functional genes, including genes responsible for As resistance, carbon and nitrogen cycling, phosphorus utilization and cytochrome c oxidases were detected. In particular, changes in community structures and activities were correlated with the biogeochemical features along the vertical soil profile when using the rbcL and nifH genes as biomarkers, evident for a gradual transition from aerobic to anaerobic lifestyles. The C/N showed marginally significant correlations with arsenic resistance (p?=?0.069) and carbon cycling genes (p?=?0.073), and significant correlation with nitrogen fixation genes (p?=?0.024). The combination of C/N, NO(3) (-) and P showed the highest correlation (r?=?0.779, p?=?0.062) with the microbial community structure. Contradict to our hypotheses, a long-term arsenic downward infiltration was not the primary factor, while the spatial isolation and nutrient availability were the key forces in shaping the community structure. This study provides new insights about the heterogeneity of microbial community metabolic potential and future biodiversity preservation for arsenic bioremediation management.",
Arsenic,1337367,"Bioaccessible arsenic in soils of former sugar cane plantations, Island of Hawaii Abstract: Arsenical herbicides were used extensively for emergent weed control in Hawaiian sugar cane cultivation from 1913 to about 1950. As a result, surface soil arsenic concentrations average 280mgkg(-1) across more than 60km(2) of former sugar plantation land in the eastern portion of the Island of Hawaii. This study was conducted to elucidate the relationship between soil properties and arsenic bioaccessibility in the iron-rich volcanic soils. Soils are predominantly Andisols, formed by weathering of basaltic lava and tephra, with pedogenic solid phases consisting of short-range order iron oxyhydroxides, allophane-like aluminosilicates, and metal-humus compounds. These reactive solid phases strongly adsorb oxyanions, such as phosphate and arsenite/arsenate. High arsenic sorption capacity limits desorption and vertical migration within the soil column and prevents contamination of the underlying groundwater aquifer, despite high arsenic loading and precipitation rates. In vitro arsenic bioaccessibility, as measured by the SBRC gastric-phase test, ranges from 2% to 35% and averages 9% of total arsenic. Bioaccessible arsenic is higher in less weathered soils (Udifolists, Typic and Lithic Hydrudands) and lower in more weathered ash-dominant soils (Acrudoxic Hydrudands). Soil weathering indicators, such as reactive iron content, are strong predictors of arsenic bioaccessibility. Based on evidence from soil mineralogy, geochemistry and arsenic speciation, as well as limited soil arsenic bioavailability/bioaccessibility comparisons, risks to human health from direct contact (soil ingestion) are significantly reduced by low arsenic bioaccessibility. Nonetheless, some soils within former sugar cane cultivation areas contain bioaccessible arsenic concentrations exceeding Hawaii Department of Health risk-based action levels, and will require mitigating actions. Even higher levels of soil arsenic contamination have been identified at former pesticide storage and mixing areas, but are generally of localized extent.",
Arsenic,2278853,"Association between anthropometric measures of obesity and subclinical atherosclerosis in Bangladesh Abstract: <strong>BACKGROUND: </strong>Anthropometric measures such as waist-hip-ratio (WHR), waist-height-ratio (WHtR), waist circumference, Mid-upper arm circumference (MUAC), and upper thigh circumference, have been linked to the risk of cardiovascular disease (CVD). However, their relationships with subclinical atherosclerosis are unclear. Studies in normal-weight populations, especially in Asian countries where leanness is prevalent, are lacking.<br /><br /><strong>METHODS: </strong>We conducted a cross-sectional study to assess the associations of WHR, WHtR, waist circumference, hip circumference, body mass index (BMI), MUAC and upper thigh circumference with carotid intima-media thickness (cIMT) among 562 middle-aged participants free of CVD in rural Bangladesh.<br /><br /><strong>RESULTS: </strong>After adjusting for age and sex, WHR and waist circumference but not BMI showed a positive significant association with cIMT. In multivariate analysis, each standard deviation (SD) increase of WHR (0.08) or WHtR (0.07) was associated with an 8.96 ?m (95% CI, 1.12-16.81) or 11.45 ?m (95%CI, 0.86-22.04) difference in cIMT, respectively, after controlling for age, sex, BMI, smoking status, education level, and systolic blood pressure (SBP). The associations of WHR and WHtR with cIMT were independent of the influence of other anthropometric measures. The associations of other anthropometric measures and cIMT were not apparent.<br /><br /><strong>CONCLUSIONS: </strong>In our relatively lean, healthy Asian population, WHR and WHtR appear to be better predictors of early atherosclerosis than other common surrogates of adiposity.",
Arsenic,627100,"Carcinogenicity of dimethylarsinic acid in Ogg1-deficient mice Abstract: Oxidative stress to DNA is recognized as a mechanism underlying carcinogenic effects of some environmental agents. Here, we hypothesized that dimethylarsinic acid (DMAV), an organic metabolite of inorganic arsenic in humans, might exert carcinogenic potential in a mouse line carrying a mutant Mmh allele of the MmhlOGG1 gene encoding the enzyme 8-hydroxyguanine DNA glycosylase 1 (OGG1). Ogg1 mutant and wild type mice were treated with DMAv in their drinking water at a dose of 200 p.p.m. for up to 72 weeks. All DMAV-treated Ogg1-1-animals developed tumors, with a tendency for lower total incidences in the Ogg1+!· cases. Lung tumors in particular were induced as compared to the lack in non-carcinogen controls and were significantly more frequent in the homozygotes. At week 4. the levels of DNA 8-0H-dG and cell proliferation were significantly elevated in the lungs of non-treated Ogg1-1- as compared to Ogg1+!· mice and were strongly enhanced by DMAv treatment. Marked induction of Pofa1. Cyp7b1. Ndfua3. Mmp13 and other genes specific to cell proliferation, cell signaling and xenobiotic metabolism in the lungs of DMAV-treated Ogg1-1 - mice was found. Electron microscopic examination revealed the growth of microvilli, with increased numbers of mitochondria only in lungs and lung tumors of DMAv-exposed Ogg1-1 - mice. Therefore. we strongly suggest that DMAv exerts carcinogenicity in the lungs of Ogg1-1mutant mice, with a possible role for persistent accumulation of DNA oxidative adducts.",
Arsenic,1597330,"GADD45? mediates p53 protein degradation via Src/PP2A/MDM2 pathway upon arsenite treatment Abstract: Growth arrest and DNA-damage-inducible, beta (GADD45?) has been reported to inhibit apoptosis via attenuating c-Jun N-terminal kinase (JNK) activation. We demonstrated here that GADD45? mediated its anti-apoptotic effect via promoting p53 protein degradation following arsenite treatment. We found that p53 protein expression was upregulated in GADD45?-/- cells upon arsenite exposure as compared with those in GADD45?+/+ cells. Further studies showed that GADD45? attenuated p53 protein expression through Src/protein phosphatase 2A/murine double minute 2-dependent p53 protein-degradation pathway. Moreover, we identified that GADD45?-mediated p53 protein degradation was crucial for its anti-apoptotic effect due to arsenite exposure, whereas increased JNK activation was not involved in the increased cell apoptotic response in GADD45?-/- cells under same experimental conditions. Collectively, our results demonstrate a novel molecular mechanism responsible for GADD45? protection of arsenite-exposed cells from cell death, which provides insight into our understanding of GADD45? function and a unique compound arsenite as both a cancer therapeutic reagent and an environmental carcinogen. Those novel findings may also enable us to design more effective strategies for utilization of arsenite for the treatment of cancers.",
Arsenic,1030124,"Environmental pollution and chronic arsenicosis in South Calcutta Abstract: Careless handling of industrial wastes often creates problems for human health and the environment. Chronic arsenic toxicity, resulting from household use of arsenic-contaminated water occurred in 53 out of 79 members (67%) of 17 families residing in South Calcutta close to a factory that manufactured Paris-green (copper acetoarsenite). Clinical investigation of 20 of these affected persons showed typical skin pigmentation as well as palmar and plantar keratosis in all of them, while gastrointestinal symptoms, anaemia and signs of liver disease and peripheral neuropathy were seen in many. The water used by the affected families for drinking and cooking had been taken from shallow tubewells and had arsenic levels from 5.0 to 58 mg/l (WHO permissible limit, 0.05 mg/l). Other residents in the same area whose drinking-water came from deep tubewells or from tap water supplied by the Calcutta Municipal Corporation (arsenic levels, less than 0.05 mg/l) were not affected. The study confirms that arsenic in the shallow tubewells was due to the waste discharged by the factory producing Paris-green.",
Arsenic,1351882,"Induction of the stress response in vivo decreases nuclear factor-kappa B activity in jejunal mucosa of endotoxemic mice Abstract: <strong>BACKGROUND: </strong>Results of previous studies suggest that the stress response protects cells and tissues by regulating proinflammatory mediators. The transcription factor nuclear factor-kappa B (NF-kappa B), normally sequestered in the cytoplasm by its inhibitory protein, I kappa B, regulates many genes involved in inflammatory responses to critical illness. Endotoxemia is associated with increased NF-kappa B activity in intestinal mucosa, but the effect of the stress response on endotoxin-induced NF-kappa B activation in intestinal mucosa is not known.<br /><br /><strong>HYPOTHESIS: </strong>Induction of the stress response inhibits NF-kappa B DNA binding activity in jejunal mucosa during endotoxemia.<br /><br /><strong>METHODS: </strong>The stress response was induced in mice by hyperthermia (42 degrees C) or injection with sodium arsenite (10 mg/kg). After 2 to 5 hours, mice were injected with endotoxin (lipopolysaccharide, 12.5 mg/kg) or a corresponding volume of sterile saline. One hour later, jejunal mucosa was harvested for preparation of nuclear and cytoplasmic extracts.<br /><br /><strong>RESULTS: </strong>Mucosal levels of heat shock protein-72 increased after hyperthermia or treatment with sodium arsenite, consistent with induction of the stress response. The increase in NF-kappa B DNA binding activity and decrease in I kappa B-alpha levels seen after endotoxin injection were inhibited by previous induction of the stress response.<br /><br /><strong>CONCLUSION: </strong>The protective effects of the stress response in vivo might, at least in part, be due to inhibited NF-kappa B activation.",
Arsenic,1018370,"p53 expression and proliferative activity in Bowen's disease with or without chronic arsenic exposure Abstract: A comparative study of Bowen's disease (BD) with or without chronic arsenic exposure may contribute to understanding arsenic carcinogenesis. We compared the p53 overexpression and proliferative activity of 26 cases of BD with chronic arsenic exposure (group I) and 22 comparable cases of BD without chronic arsenic exposure (group II) by immunohistochemical method on formalin-fixed, paraffin-embedded tissues with antibodies PAb1801 and MIB-1, respectively. We also included in this study two squamous cell carcinomas that developed from BD in group I and one in group II. Two paired BD lesions in the same individual of one patient in group I and of three patients in group II were also studied. The significant p53(+) (&gt;10% stained cells) rates were 42.3% (11 of 26) and 9.1% (2 of 22) for groups I and II, respectively, and the difference was statistically significant (P = .01). The p53 expression in different lesions of the same individual remained consistently the same. Squamous cell carcinomas that developed in 2 cases of p53(+) BD in group I were also positive, but the one in 1 case of p53(-) BD in group II was negative. No significant statistical difference in proliferative activity was found between group I BD and group II BD (P= .769), nor between p53(+) cases (&gt;10% stained cells) and p53(-) cases (&lt;10% stained cells) in group I BD (P = .519). This study showed that significant overexpression of p53 protein was higher in BD with chronic arsenic exposure. Therefore, arsenic carcinogenesis of BD might be different from that of BD unrelated to arsenic, and alteration of p53 plays a more important role in the pathogenesis of BD with chronic arsenic exposure. Overexpression of p53 was not a prerequisite for developing squamous cell carcinoma and was not affected by proliferative activity.",
Arsenic,8611,"Effects of acute sodium arsenite administration on the pulmonary chemical metabolizing enzymes, cytochrome P-450 monooxygenase, NAD(P)H: quinone acceptor oxidoreductase and glutathione S-transferase in guinea pig: comparison with effects in liver and kidney Abstract: Tissue specific changes in the cytochrome P-450 (P-450) monooxygenase system were observed following a single subcutaneous dose of sodium arsenite (75 mumol/kg), a known inducer of stress proteins. P-450 monooxygenase activities were assayed with several isozyme selective substrates; 7-ethoxyresorufin, 7-pentoxyresorufin, 4-aminobiphenyl and erythromycin. Both tissue selective and isozyme selective changes in monooxygenase activity were noted. For example, the rate of 4-aminobiphenyl N-hydroxylation (ABH) was increased by arsenite administration in lung but not in liver. Arsenite inhibited 7-ethoxyresorufin O-deethylation (ERF) in all tissues of control animals, but to a lesser extent in lung. However, increases of ERF activity occurred after arsenite treatment in lung of beta-naphthoflavone (beta NF)-treated guinea pigs whereas arsenite decreased ERF activities in the kidney and liver of these animals. These complex effects on ERF activity may in part be modulated by induction of heme oxygenase, whose activity was increased 2.5-3.5-fold in these organs by arsenite. The highest heme oxygenase activity was found in kidney with lower activities being present in liver and lung, respectively. These data are consistent with the decreased P-450 content observed in kidney and liver microsomes of arsenite treated guinea pigs. On the other hand there was either no change or a slight increase (about 2-fold) in the pulmonary microsomal P-450 content of these animals. A complex pattern of induction for the non-heme, Ah locus associated enzyme, NAD(P)H:quinone acceptor oxidoreductase (QOR) was also observed. With menadione as substrate arsenite treatment increased QOR activity in all tissues studied. However, with dichlorophenolindophenol (DCPIP) as substrate a significant arsenite effect was observed only in the kidney. Significant differences between the QOR substrates were also observed in beta NF-treated guinea pigs and control animals. Our results are consistent with the presence of more than one form of QOR in the guinea pig. Arsenite treatment also caused an increase in glutathione S-transferase activity, with 2,4-dinitro-1-chlorobenzene (DNCB) as substrate, of guinea pig kidney but not liver or lung.",
Arsenic,1347575,"Ecological risk of Irgarol 1051 and its major metabolite in coastal California marinas and reference areas Abstract: The objective of this study was to use a probabilistic approach to determine the ecological risk of Irgarol and its major metabolite (GS26575) in coastal California marinas and reference areas by using monitoring data collected during the summer of 2006. Distributions of environmental exposure data were compared with the distribution of plant species response data from laboratory toxicity studies and the no observed effect concentration (NOEC) from a microcosm study to quantify the likelihood and significance of ecological risk. Toxicity testing indicates plants are much more sensitive to Irgarol than animals; therefore, the conservative effects benchmark used to characterize risk was the plant 10th centile for both Irgarol (193 ng/L) and GS26575 (5622 ng/L). In addition, the microcosm NOEC of 323 ng/L was also used to characterize risk. Irgarol concentrations from 15 California marinas ranged from 1.45 to 339 ng/L while GS26575 concentrations ranged from non-detected to 74 ng/L. The probability of exceeding the Irgarol plant 10th centile of 193 ng/L for 15 marinas sampled in coastal California in 2006 was 7.3% while the probability of exceeding the microcosm NOEC of 323 ng/L was even lower (5.5%). In general, this probability of exceedence for either effects benchmark and subsequent ecological risk is considered to be low for these marinas as only one marina (Kings Harbor marina in Redondo Beach) had measured concentrations of Irgarol exceeding 193 ng/L. Irgarol exposure is concentrated within marinas and ecological risk from Irgarol exposure in adjoining reference areas was judged to be very low. Ecological risk from GS26575 exposure was also low in both marina and reference areas in California.",
Arsenic,759886,"Genetic polymorphisms in glutathione S-transferase (GST) superfamily and risk of arsenic-induced urothelial carcinoma in residents of Southwestern Taiwan Abstract: ABSTRACT: BACKGROUND: S: Arsenic exposure is an important public health issue worldwide. Dose-response relationship between arsenic exposure and risk of urothelial carcinoma (UC) is consistently observed. Inorganic arsenic is methylated to form the metabolites monomethylarsonic acid and dimethylarsinic acid while ingested. Variations in capacity of xenobiotic detoxification and arsenic methylation might explain individual variation in susceptibility to arsenic-induced cancers. METHOD: S: To estimate individual susceptibility to arsenic-induced UC, 764 DNA specimens from our long-term follow-up cohort in Southwestern Taiwan were used and the genetic polymorphisms in GSTM1, GSTT1, GSTP1 and arsenic methylation enzymes including GSTO1 and GSTO2 were genotyped. RESULTS: : The GSTT1 null was marginally associated with increased urothelial carcinoma (UC) risk (HR, 1.91, 95% CI, 1.00-3.65), while the association was not observed for other GSTs. Among the subjects with cumulative arsenic exposure (CAE) [greater than or equal to] 20 mg/L*year, the GSTT1 null genotype conferred a significantly increased cancer risk (RR, 3.25, 95% CI, 1.20-8.80). The gene-environment interaction between the GSTT1 and high arsenic exposure with respect to cancer risk was statistically significant (multiplicative model, p=0.0151) and etiologic fraction was as high as 0.86 (95% CI, 0.51-1.22). The genetic effects of GSTO1/GSTO2 were largely confined to high arsenic level (CAE [greater than or equal to] 20). Diplotype analysis showed that among subjects exposed to high levels of arsenic, the AGG/AGG variant of GSTO1 Ala140Asp,GSTO2 5'UTR (-183)A/G, and GSTO2 Asn142Asp was associated with an increased cancer risk (HRs, 4.91, 95% CI, 1.02-23.74) when compared to the all-wildtype reference, respectively. CONCLUSIONS: : The GSTs do not play a critical role in arsenic-induced urothelial carcinogenesis. The genetic effects of GSTT1 and GSTO1 on arsenic-induced urothelial carcinogenesis are largely confined to very high exposure level.",
Arsenic,494288,"Synergistic effect of polymorphisms of paraoxonase gene cluster and arsenic exposure on electrocardiogram abnormality Abstract: Arsenic has been linked to increased prevalence of cancer and cardiovascular disease (CVD). but the long-term impact of arsenic exposure remains unclear. Human paraoxonase (PON1) is a high-density lipoprotein-associated antioxidant enzyme which hydrolyzes oxidized lipids and is thought to be protective against atherosclerosis, but evidence remains limited to case-control studies. Only recently have genes encoding enzymes responsible for arsenic metabolism, such as AS3MT and GSTO, been cloned and characterized. This study was designed to evaluate the synergistic interaction of genetic factors and arsenic exposure on electrocardiogram abnormality. A total of 216 residents from three tap water implemented villages of previous arseniasis-hyperendemic regions in Taiwan were prospectively followed for an average of 8 years. For each resident, a 12-lead conventional electrocardiogram (ECG) was recorded and coded by Minnesota Code standard criteria. Eight functional polymorphisms of PON1, PON2, AS3MT GSTO1, and GSTO2 were examined for genetic susceptibility to ECG abnormality. Among 42 incident cases with ECG deterioration identified among 121 baseline-normal subjects. arsenic exposure was significantly correlated with incidence of ECG abnormality. In addition, polymorphisms in two paraoxonase genes were also found associated with the incidence of ECG abnormality. A haplotype R-C-S constituted by polymorphisms of PON1 Q192R, -108C/T and PON2 C311S was linked to the increased risk. Subjects exposed to high levels of As (cumulative As exposure >14.7 ppm-year or drinking artesian well water >21 years) and carrying the R-C-S haplotype had significantly increased risks for ECG abnormality over those with only one risk factor. Results of this study showed a long-term arsenic effect on ECG abnormality and significant gene-gene and gene-environment interactions linked to the incidence of CVD. This finding might have important implications for a novel and potentially useful biomarker of arsenic risk. (C) 2008 Elsevier Inc. All rights reserved.",
Arsenic,1020871,"Toxicity and metabolism of subcytotoxic inorganic arsenic in human renal proximal tubule epithelial cells (HK-2) Abstract: Arsenic is an environmental toxicant and a human carcinogen. The kidney, a known target organ of arsenic toxicity, is critical for both in vivo arsenic biotransformation and elimination. This study investigates the potential of an immortalized human proximal tubular epithelial cell line, HK-2, to serve as a representative model for low level exposures of the human kidney to arsenic. Subcytotoxic concentrations of arsenite (&lt; or = 10 micromol/L) and arsenate (&lt; 100 micromol/L) were determined by leakage of LDH from cells exposed for 24 h. Threshold concentrations of arsenite (between 1 and 10 micromol/L) and arsenate (between 10 and 25 micromol/L) were found to affect MTT processing by mitochondria. Biotransformation of subcytotoxic arsenite or arsenate was determined using HPLC-ICP-MS to detect metabolites in cell culture media and cell lysates. Following 24 h, analysis of media revealed that arsenite was minimally oxidized to arsenate and arsenate was reduced to arsenite. Only arsenite was detected in cell lysates. Pentavalent methylated arsenicals were not detected in media or lysates following exposure to either inorganic arsenical. The activities of key arsenic biotransformation enzymes--MMAV reductase and AsIII methyltransferase--were evaluated to determine whether HK-2 cells could reduce and methylate arsenicals. When compared to the activities of these enzymes in other animal tissues, the specific activities of HK-2 cells were indicative of a robust capacity to metabolize arsenic. It appears this human renal cell line is capable of biotransforming inorganic arsenic compounds, primarily reducing arsenate to arsenite. In addition, even at low concentrations, the mitochondria are a primary target for toxicity.",
Arsenic,1247152,"Changes in Anti-Oxidant Enzyme Profile during Haematological Malignancy Abstract: Reactive oxygen species can initiate lipid peroxidation and DNA damage leading to mutagenesis, carcinogenesis and cell death, if the antioxidant system is impaired. The present work aimed to study the changes in the quantitative in vitro activities of the antioxidant enzymes - glutathione peroxidase and superoxide dismutase in the whole blood of our study group. Our study group included both blood cancer patients and age, sex matched healthy controls. We found significant decreases in the activities of both glutathione peroxidase and superoxide dismutase in patients as compared with healthy controls: Our previous work has indicated elevated arsenic concentration in the biosamples of patients. Thus, haematological malignancy is found to be associated with changes in the antioxidant defense system which is correlated with arsenic toxicity.",
Arsenic,1355007,"Comparing the health risk of toxic metals through vegetable consumption between industrial polluted and non-polluted fields in Shaoguan, south China Abstract: This study determined concentrations of lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg) and zinc (Zn) in 127 rhizosphere soil and 127 vegetable samples collected from Shaoguan, south China. The Chinese National Standard and the Target Hazard Quotient (THQ) were used to compare the risk of these toxic metals through vegetable consumption in four zones, including three industrial polluted zones (P1, P2 and P3) and one non-polluted zone (P4). Results showed that in three industrial zones, the levels of Pb, Cd, As, Hg, and Zn in vegetable rhizosphere soils exceeded the Chinese National Standard (GB15618-1995) by 9.09%, 87.9%, 8.08%, 32.3% and 18.2%, respectively, and Cd was the major pollution source. Mean contents of tested heavy metals in vegetables in three industrial zones (P1, P2 and P3) were significantly higher than that in the non-polluted zone (P4), and the levels of Pb, Cd, As and Hg in vegetables of three industrial zones exceeded the Chinese National Standard (GB 2762-2005) by 33.9%, 35.4%, 42.5% and 9.4%, respectively. The THQ of vegetables in four zones occurred at 0.13 – 1.2 for Pb, 0.28 – 4.0 for Cd, 0.55 – 2.3 for As, 0.0048 – 0.030 for Hg, and 0.064 – 0.11 for Zn. All THQ values in the non-polluted Danxia town (P4) were below the FAO/WHO permissible limit (THQ < 1). In contrast, the THQ of Cd in the industrial polluted Shaoguan Smelting Plant (P1) and Fankou Pb and Zn Mine (P2), and that of As in Shaoguan Smelting Plant (P1) and Plastics Factory (P3) exceeded the FAO/WHO permissible limit (THQ > 1). Our work suggests that the exposure risk of relevant heavy metals through vegetable consumption was higher to children compared with mid-ages and aged people. Toxic metal contamination through consumption of vegetable grown around the industrial zones imposed a great health risk on local inhabitant.",
Arsenic,8429,"Arsenic and noncirrhotic portal hypertension Abstract: Two patients have been studied in whom portal hypertension occurred after 3 and 22 years treatment with Fowler's solution (arsenic trioxide 1%). One patient had taken about 6 g of arsenic and the other 25 to 29 g. Each patient had other side effects due to arsenic ingestion. One had skin pigmentation, skin tumors, carcinoma of the larynx, and a probable bronchial carcinoma, and the other had skin pigmentation and keratoses. The level of arsenic in the liver of 1 patient was very high. Histological examination of the liver in both patients showed portal tract fibrosis and an increase in the number of portal veins. In 1 patient there was slight sclerosis around the portal veins, and in the other the portal veins were greatly thickened and had hypertrophic muscular walls. Repeated histological examinations of the liver failed to reveal cirrhosis in either patient. In both patients, the wedged hepatic vein pressure was virtually normal while the intrasplenic pressure was high, indicating that the obstruction to portal flow resided in the portal tracts. It is possible that arsenic is an etiological factor in the production of noncirrhotic portal hypertension in some patients, perhaps because of damage to the intrahepatic portal veins.",
Arsenic,627374,"Arsenic exposure from drinking water and risk of premalignant skin lesions in Bangladesh: Baseline results from the Health Effects of Arsenic Longitudinal Study Abstract: Millions of persons around the world are exposed to low doses of arsenic through drinking water. However, estimates of health effects associated with low-dose arsenic exposure have been extrapolated from high-dose studies. In Bangladesh, many persons have been exposed to a wide range of doses of arsenic from drinking water over a significant period of time. The authors evaluated dose-response relations between arsenic exposure from drinking water and premalignant skin lesions by using baseline data on 11,746 participants recruited in 2000-2002 for the Health Effects of Arsenic Longitudinal Study in Araihazar, Bangladesh. Several measures of arsenic exposure were estimated for each participant based on well-water arsenic concentration and usage pattern of the wells and on urinary arsenic concentration. In different regression models, consistent dose-response effects were observed for all arsenic exposure measures. Compared with drinking water containing <8.1 microg/liter of arsenic, drinking water containing 8.1-40.0, 40.1-91.0, 91.1-175.0, and 175.1-864.0 microg/liter of arsenic was associated with adjusted prevalence odds ratios of skin lesions of 1.91 (95% confidence interval (CI): 1.26, 2.89), 3.03 (95% CI: 2.05, 4.50), 3.71 (95% CI: 2.53, 5.44), and 5.39 (95% CI: 3.69, 7.86), respectively. The effect seemed to be influenced by gender, age, and body mass index. These findings provide information that should be considered in future research and policy decisions.",
Arsenic,1019718,"In vitro cytotoxicity of IgG antibodies on vascular endothelial cells from patients with endemic peripheral vascular disease in Taiwan Abstract: A unique peripheral vascular disorder called 'blackfoot disease' is endemic in a limited area on the south-west coast of Taiwan. Clinically, the signs and symptoms of blackfoot disease (BFD) are similar to those of arteriosclerosis and Buerger's disease. A destruction of vascular endothelial cells (ECs) takes place at an early stage in the affected limbs. Currently, the cause of BFD is believed to be artesian drinking water containing a high concentration of arsenic and/or humic substances, although the mechanism of EC destruction is not entirely understood. The purpose of the present study was to examine the factors related to EC damage in BFD. Thus, we investigated the effects of purified IgG collected from patients with BFD (BFD-IgG) and from normal controls (N-IgG) on cultured EC. We found that: (1) EC binding activity of BFD-IgG was significantly higher than that of N-IgG; (2) BFD-IgG, at a concentration higher than 100 microg/ml but not N-IgG, induced concentration-dependent EC cytotoxicity; (3) BFD-IgG at a concentration of 100 microg/ml stimulated neither the release of von Willebrand factor nor the expression of intercellular adhesion molecule-1 by EC. Fluorescent video microscopic examination revealed an increase in transcapillary and interstitial diffusion of nailfold capillary loops in clinically normal fingers of BFD patients. These findings strongly suggested that immunological mechanisms played a significant role in the pathogenesis of BFD. We propose that only persons who produce the IgG anti-endothelial cell antibody are potential victims of BFD.",
Arsenic,1519059,"Metal tolerance and larvicidal activity of Lysinibacillus sphaericus Abstract: Lysinibacillus sphaericus is a spore-forming bacterium used in the biological control of mosquitoes and in bioremediation. Mosquito larvae exposed to heavy metals are tolerant to concentrations above the permissible limit for industrial residual waters. In this work, we characterize 51 L. sphaericus strains for metal tolerance and larvicidal activity against Culex quinquefasciatus. Lysinibacillus sphaericus OT4b.2, OT4b.20, OT4b.25, OT4b.26 and OT4b.58 were as toxic as the spores of the reference strain 2362 against C. quinquefasciatus larvae. 19 Mosquito-pathogenic L. sphaericus strains and 6 non-pathogenic strains were able to grow in arsenate, hexavalent chromium and/or lead. 16S rRNA gene sequences and phylogenetic analyses clustered 84 % of the metal-tolerant strains in L. sphaericus group 1, which encompasses the mosquitocidal strains. The larvicidal activity of vegetative and sporulated cells and its high tolerance to arsenate, hexavalent chromium and lead indicate that L. sphaericus OT4b.26 is a strong candidate for further studies examining its potential for biological control of mosquitoes in waters contaminated with metals.",
Arsenic,2347763,Infrared luminescence in Bi-doped Ge-S and As-Ge-S chalcogenide glasses and fibers Abstract: Experimental and theoretical studies of spectral properties of chalcogenide Ge-S and As-Ge-S glasses and fibers are performed. A broad infrared (IR) luminescence band which covers the 1.2 - 2.3 mu m range with a lifetime about 6 mu s is discovered. Similar luminescence is also present in optical fibers drawn from these glasses. Arsenic addition to Ge-S glass significantly enhances both its resistance to crystallization and the intensity of the luminescence. Computer modeling of Bi-related centers shows that interstitial Bi+ ions adjacent to negatively charged S vacancies are most likely responsible for the IR luminescence. (C) 2014 Optical Society of America,
Arsenic,1453809,"Alterations in glutathione levels and apoptotic regulators are associated with acquisition of arsenic trioxide resistance in multiple myeloma Abstract: Arsenic trioxide (ATO) has been tested in relapsed/refractory multiple myeloma with limited success. In order to better understand drug mechanism and resistance pathways in myeloma we generated an ATO-resistant cell line, 8226/S-ATOR05, with an IC50 that is 2-3-fold higher than control cell lines and significantly higher than clinically achievable concentrations. Interestingly we found two parallel pathways governing resistance to ATO in 8226/S-ATOR05, and the relevance of these pathways appears to be linked to the concentration of ATO used. We found changes in the expression of Bcl-2 family proteins Bfl-1 and Noxa as well as an increase in cellular glutathione (GSH) levels. At low, clinically achievable concentrations, resistance was primarily associated with an increase in expression of the anti-apoptotic protein Bfl-1 and a decrease in expression of the pro-apoptotic protein Noxa. However, as the concentration of ATO increased, elevated levels of intracellular GSH in 8226/S-ATOR05 became the primary mechanism of ATO resistance. Removal of arsenic selection resulted in a loss of the resistance phenotype, with cells becoming sensitive to high concentrations of ATO within 7 days following drug removal, indicating changes associated with high level resistance (elevated GSH) are dependent upon the presence of arsenic. Conversely, not until 50 days without arsenic did cells once again become sensitive to clinically relevant doses of ATO, coinciding with a decrease in the expression of Bfl-1. In addition we found cross-resistance to melphalan and doxorubicin in 8226/S-ATOR05, suggesting ATO-resistance pathways may also be involved in resistance to other chemotherapeutic agents used in the treatment of multiple myeloma.",
Arsenic,627289,"The lack of a specific association between arsenic in drinking water and hepatocellular carcinoma Abstract: BACKGROUND/AIMS: Liver cancers, particularly angiosarcomas, among patients with arsenic intoxication have been reported for more than half a century. Studies on cancers of urinary system and skin showed the carcinogenic effect of arsenic was cell-type specific. To evaluate whether this is also true for liver cancers, a study was conducted in 243 townships in Taiwan. METHODS: Cases of liver cancer were identified through the National Cancer Registry Program. The distribution of major cell-types was compared between an endemic area of arsenic intoxication, including 5 of the 243 townships, and the rest of the townships. RESULTS: A total of 40,832 patients with liver cancer, including 32,034 men and 8798 women, were diagnosed between January 1, 1980 and December 31, 1999 in the study townships. Distributions of the two major cell-types, hepatocellular carcinoma and cholangiocarcinoma, did not appear to be different between the arsenic intoxication endemic area and the other areas. The rest of the cell-types did not have enough cases to provide stable estimates. CONCLUSIONS: Convincing evidence in the literature has suggested a specific association between angiosarcoma of liver and arsenic ingestion, but the current study did not find such an association for hepatocellular carcinoma, although it is the major cell-type.",
Arsenic,1936054,"Bioaccumulation of Arsenic and Cadmium in Birch and Lime from the Bor Region Abstract: Copper production in the Bor region (east Serbia) during the last 100 years has influenced the quality of soil, water, and air. This pollution has endangered not only the biotope but all living organisms, including humans. Contents of arsenic (As) and cadmium (Cd) were analyzed in Betula sp. (birch) and Tillia sp. (lime) within the Bor region with the aim to investigate the bioaccumulation of these highly toxic, nonessential trace elements in selected plants, which may be important for biomonitoring and bioremediation purposes. The results of statistical data analysis showed that several factors influenced the bioaccumulation of trace elements in the examined plants, of which soil pH, soil content, and mechanism of accumulation were the main factors. The greatest As and Cd concentrations were found in plant material from the Bor center sampling site in the urban/industrial zone, which is in close proximity to the pollution source, due to the greatest metal concentrations in soil and the lowest soil pH. The low values of biological accumulation coefficients (bioconcentration factor &lt;1, mobility ratio &lt;1) pointed to a low rate of uptake and accumulation of As and Cd in lime and birch. Trace elements showed different patterns of behavior and accumulation in the trees. Lime showed a high ability of assimilation through leaves, whereas birch showed a better potential to express a linear correlation between concentrations in plant parts and soil.",
Arsenic,1338655,"Quantifying the effect of nanoparticles on As(V) ecotoxicity exemplified by nano-Fe(2) O(3) (magnetic) and nano-Al(2) O(3) Abstract: Nano-Fe(2) O(3) (magnetic) and nano-Al(2) O(3) are increasingly used in biomedical fields for cellular labeling and drug delivery, and in the industry as catalysts. However, they may also serve as carriers of toxic contaminants and negatively impact the environment and human health. In the present study, Ceriodaphnia dubia was used to assess the toxicity of these nanoparticles (NPs) with and without the presence of background arsenic(V) (As[V]). The results showed that although these NPs alone did not exhibit significant toxicity in the experimental concentration range, they could significantly enhance the toxicity of As(V). The accumulation of As(V) on nano-Fe(2) O(3) (m) and nano-Al(2) O(3) , as well as the uptake of these NPs in C. dubia, were verified. An inverse relationship between the median lethal concentration (LC50) of the soluble As(V) and the accumulation of NPs in C. dubia was developed. Therefore, the uptake of As(V)-loaded NPs in C. dubia played a key role in enhancing As(V) toxicity.",
Arsenic,2278024,"Multiple linear and principal component regressions for modelling ecotoxicity bioassay response Abstract: The ecotoxicological response of the living organisms in an aquatic system depends on the physical, chemical and bacteriological variables, as well as the interactions between them. An important challenge to scientists is to understand the interaction and behaviour of factors involved in a multidimensional process such as the ecotoxicological response. With this aim, multiple linear regression (MLR) and principal component regression were applied to the ecotoxicity bioassay response of Chlorella vulgaris and Vibrio fischeri in water collected at seven sites of Leça river during five monitoring campaigns (February, May, June, August and September of 2006). The river water characterization included the analysis of 22 physicochemical and 3 microbiological parameters. The model that best fitted the data was MLR, which shows: (i) a negative correlation with dissolved organic carbon, zinc and manganese, and a positive one with turbidity and arsenic, regarding C. vulgaris toxic response; (ii) a negative correlation with conductivity and turbidity and a positive one with phosphorus, hardness, iron, mercury, arsenic and faecal coliforms, concerning V. fischeri toxic response. This integrated assessment may allow the evaluation of the effect of future pollution abatement measures over the water quality of Leça River.",
Arsenic,2088549,"Structure of a Prokaryotic Sodium Channel Pore Reveals Essential Gating Elements and an Outer Ion Binding Site Common to Eukaryotic Channels Abstract: Voltage-gated sodium channels (NaVs) are central elements of cellular excitation. Notwithstanding advances from recent bacterial NaV (BacNaV) structures, key questions about gating and ion selectivity remain. Here, we present a closed conformation of NaVAe1p, a pore-only BacNaV derived from NaVAe1, a BacNaV from the arsenite oxidizer Alkalilimnicola ehrlichei found in Mono Lake, California, that provides insight into both fundamental properties. The structure reveals a pore domain in which the pore-lining S6 helix connects to a helical cytoplasmic tail. Electrophysiological studies of full-length BacNaVs show that two elements defined by the NaVAe1p structure, an S6 activation gate position and the cytoplasmic tail &quot;neck&quot;, are central to BacNaV gating. The structure also reveals the selectivity filter ion entry site, termed the &quot;outer ion&quot; site. Comparison with mammalian voltage-gated calcium channel (CaV) selectivity filters, together with functional studies, shows that this site forms a previously unknown determinant of CaV high-affinity calcium binding. Our findings underscore commonalities between BacNaVs and eukaryotic voltage-gated channels and provide a framework for understanding gating and ion permeation in this superfamily.",
Arsenic,2278315,"Characterization of As and trace metals embedded in PM10 particles in Puebla City, México Abstract: Forty-eight air-filter samples (PM10) were analysed to identify the concentration level of partially leached metals (PLMs; As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and V) from Puebla City, México. Samples were collected during 2008 from four monitoring sites: (1) Tecnológico (TEC), (2) Ninfas (NIN), (3) Hermanos Serdán (HS) and (4) Agua Santa (AS). The results indicate that in TEC, As (avg. 424 ng m(-3)), V (avg. 19.2 ng m(-3)), Fe (avg. 1,202 ng m(-3)), Cu (avg. 86.6 ng m(-3)), Cr (41.9 ng m(-3)) and Ni (18.6 ng m(-3)) are on the higher side than other populated regions around the world. The enrichment of PLMs is due to the industrial complexes generating huge dust particles involving various operations. The results are supported by the correlation of metals (Mn, Cd and Co) with Fe indicating its anthropogenic origin and likewise, As with Cd, Co, Fe, Mn, Pb and V. The separate cluster of As, Fe and Mn clearly signifies that it is due to continuous eruption of fumaroles from the active volcano Popocatépetl in the region.",
Arsenic,1034152,"Vaporization of solids: Evidence for a zipper mechanism in the retarded vaporization of arsenic Abstract: Recent observations indicate that the rate of evaporation of elemental arsenic into a vacuum is determined by the rate of formation, at screw dislocations, of kinks in ledges of molecular height. Once formed, a kink advances along the ledge, which makes a continuous spiral ramp outward from the dislocation, until the ledge terminates. A kink advances by releasing As(4) molecules from the ledge. A given kink releases almost 10(6) As(4) molecules before the next kink is initiated.",
Arsenic,1269277,"Occupational exposure to dust: Inflammation and ischemic heart disease Abstract: The association between occupational exposure to dust and ischemic heart disease (IHD) was reviewed. Case control studies were cited which indicated a high risk of myocardial infarction and IHD among workers exposed to quartz (14808607). In a cohort study, men with asbestosis or impaired lung function had an elevated risk of IHD. Chimney sweeps, aluminum production workers, and car mechanics exposed to polycyclic aromatic hydrocarbons also had a high risk of IHD. In one case control study, exposure to arsenic (7440382) increased the risk of heart disease. Excess mortality caused by heart diseases was reported in a cohort of workers exposed to beryllium (7440417). Another review indicated that lead (7439921) exposure resulted in high blood pressure and an increased incidence of cerebrovascular disease. Farmers, exposed to organic dusts, had elevated plasma fibrinogen levels and were at increased risk of coronary death. A high risk of IHD was determined among sawyers exposed to wood dust. Paper and paper pulp workers who were exposed to irritant gases and paper dust were at an increased risk of myocardial infarction. Among welders exposed to gases and respirable particles, a slightly elevated risk of myocardial infarction and an increased risk of symptoms of angina pectoris were noted. The author concludes that the relationship between occupational exposure to dust and IHD should be studied by comparing the blood fibrinogen concentrations in exposed and unexposed workers. Confounders, such as smoking, should be considered.",
Arsenic,1348257,Biosorptive behaviour of mango leaf powder and rice husk for arsenic(III) from aqueous solutions Abstract: ,
Arsenic,1019774,"Assessment of health risks due to hazardous air pollutant emissions from electric utilities Abstract: Hazardous air pollutant (HAP) emissions from electric utilities were evaluated. Cancer risks, as well as noncancer effects, due to inhalation exposure were assessed for 67 HAPs. Also, cancer risks due to multipathway exposure to radionuclide emissions were assessed. In addition, an assessment of the fate of mercury (Hg) through various environmental media was included. Results suggest arsenic, chromium, and nickel are the HAPs that present the highest cancer risk due to inhalation exposure. For noncancer effects due to inhalation exposure, hydrogen chloride appears to present the greatest potential concern. The risks due to multipathway exposure to radionuclides are estimated to be of similar magnitude to the risks posed by inhalation of arsenic and nickel. Mercury is of potential concern for multipathway exposures because it persists in the environmental and bioaccumulates in the aquatic food web. The study suggests there is a plausible link between Hg emissions from utilities and the Hg found in soil, water, and freshwater fish.",
Arsenic,1349212,"Impacts of sulfur regulation in vivo on arsenic accumulation and tolerance of hyperaccumulator Pteris vittata Abstract: The impacts of the regulation of sulfur (S) metabolism in vivo on arsenic (As) and S species and on As accumulation by Pteris vittata L. were investigated using a synchrotron-based X-ray-absorption fine structure method. The S assimilation inhibitor l-buthionine-sulfoximine (BSO) markedly inhibited As reduction, doubling arsenate (As(V)) content in P. vittata rhizoids. The resulting As transport blockage in rhizoids, decreased As movement to aboveground tissues by 47%. The significant impact of BSO demonstrated the vital role of sulfhydryl groups (single bondSH) as reductants in As(V) reduction and confirmed the importance of As(V) reduction in As accumulation in this fern. The S metabolism accelerant O-acetyl-l-serine resulted in the appearance of large amounts of As–SH in rhizoids and had no obvious impact on As accumulation, but with As stress conditions, effectively increased plant biomass, possibly through chelation of excess As with single bondSH. Thus, single bondSH appeared able to act as both a reductant and a chelator of As in P. vittata, and the ratio of single bondSH to As may have been a factor that determined the specific role of single bondSH in P. vittata under these conditions.",
Arsenic,1337654,"Assessing heavy metal pollution using Great Tits (Parus major): feathers and excrements from nestlings and adults Abstract: Passerine species have been increasingly used as bioindicators of metal bioaccumulation especially by taking benefit of non-invasive procedures, such as collecting feathers and excrements. In 2009, metal (As, Cd, Cu, Hg, Ni, Pb, Se and Zn) concentrations were determined in feathers and excrements of nestling and adult female great tits (Parus major) in industrial (a paper mill) and rural sites in maritime pine forests on the west coast of Portugal. The aim of this study was to compare the levels of metals between the areas but also between sampling methods (feather vs. excrement) and age classes (nestling vs. adult). Although excrements and feathers of nestling great tits showed different concentrations, similar patterns of accumulation were detected in both study areas. There was a significantly higher concentration of mercury in the industrial area and significantly higher concentrations of arsenic in the rural area in both sample types. Metal levels in adult females had quite different results when compared to nestlings, and only nickel presented significantly higher levels near the paper mill. Since metal levels showed a consistent pattern in feathers and excrements of nestling great tits, we conclude that both represent good and non-invasive methods for the evaluation of these elements in polluted areas.",
Arsenic,628674,"Arsenic-induced skin conditions identified in southwest dermatology practices: An epidemiologic tool? Abstract: Populations living in the Southwest United States are more likely to be exposed to elevated drinking water arsenic levels compared to other areas of the country. Skin changes, including hyperpigmentation and generalized hyperkeratosis, are the most common signs of chronic arsenic ingestion from drinking water. The purpose of this study was to determine the feasibility of using dermatology practices in New Mexico, Arizona, and western Texas as a surveillance system for arsenical skin disorders related to drinking water. Postcard questionnaires were mailed to practicing dermatologists. The number of cases of arsenical hyperpigmentation/keratoses seen by these dermatologists during the past 10 years and the past year were estimated. Of 240 dermatologists who were mailed questionnaires, 37 reported seeing 237 patients with arsenical hyperpigmentation/keratoses in the past 10 years and 35 patients in the past year. Since approximately one-eighth of dermatologists practicing in the Southwest saw at least one patient with arsenical hyperpigmentation/keratoses during one year, it appears feasible to complete a population-based study of these conditions.",
Arsenic,628465,"Differential susceptibility to carcinogen-induced amplification of sv40 and dhfr sequences in sv40-transformed human keratinocytes Abstract: Gene amplification contributes to carcinogenesis by enhancing proto-oncogene activity and causing chromosomal instability. The ease of detecting amplified tumor-virus sequences has encouraged use of this system as a surrogate for studying the molecular events involved in endogenous gene amplification. We report here a new system for studying carcinogen-induced amplification of both endogenous and viral sequences in the SV40-transformed human keratinocyte line AG06. Treatment with carcinogens induced a transient dose-dependent amplification of the integrated SV40 sequences. The amplified sequences appeared in the extra-chromosomal fraction. Treatment of these cells with carcinogens prior to methotrexate (MTX) selection increased the frequency of MTX-resistant colonies, 67% of which exhibited dihydrofolate reductase (dhfr) amplification. The abilities of five carcinogens with different DNA-damaging activities (the DNA-damaging agents N-methyl-N-nitro-N-nitrosoguanidine, mitomycin C (MMC), ultraviolet light C, and X-rays and the non-DNA-damaging agent arsenite) to induce SV40 and dhfr amplification at concentrations that result in 50% clonal survival were compared. All four DNA-damaging carcinogens (as well as growth arrest) were able to elicit some SV40 amplification, but responses varied markedly, from 1.8-fold for X-rays to sevenfold to eightfold for MMC. There was no correlation between the ability to elicit the two amplification responses. Arsenite, which did not induce SV40 amplification, was the best inducer of MTX resistance. These results point to different controls involved in the induction of viral and dhfr amplification. The signal for amplification of viral genes may be triggered by DNA damage and growth arrest, whereas amplification of dhfr, and perhaps other endogenous sequences, seems to be triggered by other signals as well.",
Arsenic,656857,"Occupational exposures and pancreatic cancer: A meta-analysis Abstract: OBJECTIVES: Consolidation of epidemiological data on pancreatic cancer and worksite exposures. METHODS: Publications during 1969-98 were surveyed. Studies without verified exposures were excluded. Meta-analyses were conducted on data from 92 studies covering 161 populations, with results for 23 agents or groups of agents. With a standard format, five epidemiologists extracted risk estimates and variables of the structure and quality of each study. The extracted data were centrally checked. Random meta-models were applied. RESULTS: Based on 20 populations, exposure to chlorinated hydrocarbon (CHC) solvents and related compounds was associated with a meta-risk ratio (MRR) of 1.4 (95% confidence interval (95% CI) 1.0 to 1.8). Nickel and nickel compounds were considered in four populations (1.9; 1.2 to 3.2). Excesses were found also for chromium and chromium compounds (1.4; 0.9 to 2.3), polycyclic aromatic hydrocarbons (PAHs) (1.5; 0.9 to 2.5), organochlorine insecticides (1.5; 0.6 to 3.7), silica dust (1.4; 0.9 to 2.0), and aliphatic and alicyclic hydrocarbon solvents (1.3; 0.8 to 2.8). Evidence on pancreatic carcinogenicity was weak or non-positive for the following agents: acrylonitrile (1.1; 0.0 to 6.2); arsenic (1.0; 0.6 to 1.5); asbestos (1.1; 0.9 to 1.5); diesel engine exhaust (1.0; 0.9 to 1.3); electromagnetic fields (1.1; 0.8 to 1.4); formaldehyde (0. 8; 0.5 to 1.0); flour dust (1.1; 0.3 to 3.2); cadmium and cadmium compounds (0.7; 0.4 to 1.4); gasoline (1.0; 0.8 to 1.2); herbicides (1.0; 0.8 to 1.3); iron and iron compounds (1.3; 0.7 to 2.5); lead and lead compounds (1.1; 0.8 to 1.5); man-made vitreous fibres (1.0; 0.6 to 1.6); oil mist (0.9; 0.8 to 1.0); and wood dust (1.1; 0.9 to 2.5). The occupational aetiological fraction of pancreatic cancer was estimated at 12%. In a subpopulation exposed to CHC solvents and related compounds, it was 29%; to chromium and chromium compounds, 23%; to nickel and nickel compounds, 47%; to insecticides, 33%; and to PAHs, 33%. CONCLUSION: Occupational exposures may increase risk of pancreatic cancer. High quality studies are called for on interactions between occupational, environmental, and lifestyle factors as well as interactions between genes and the environment.",
Arsenic,513005,"Arsenic interactions with lipid particles containing iron Abstract: While arsenic is toxic to all multicellular organisms, some organisms become tolerant by an unknown mechanism. We have recently uncovered an inducible tolerance mechanism in insects, which is based on a sequestration of toxins and pathogens by lipid particles. To examine whether arsenic interacts with lipid particles from mammals we compared binding of arsenic to lipid particles from insect and pig plasma after separation of lipid particles by low-density gradient centrifugation. Arsenic was found in both organisms in an area of the gradient, which corresponds to lipid-rich lipid particles. Since iron is known to affect arsenic toxicity in some organisms, we asked whether iron may be present in lipid particles. When low density cell (LDC) gradient fractions were analysed for the presence of iron we detected a peak in very low-density fractions similar to those that carried arsenic. This could indicate that arsenic interacts with lipid particles that contain iron and, if arsenic is removed from the plasma by lipid particles, that would also reduce iron-containing lipid particles at the time of arsenic emergence in the plasma. To test this assumption we measured the iron content in plasma at various time periods after the toxin ingestion. This time Course revealed that iron is depleted in plasma fractions when arsenic shows a peak. Our data suggest that arsenic interacts with invertebrate and vertebrate lipid particles that are associated with proteins that may lead to detoxification by cell-free or cellular sequestration mechanisms.",
Arsenic,2343551,"The perils and promises of microbial abundance: Novel natures and model ecosystems, from artisanal cheese to alien seas Abstract: Microbial life has been much in the news. From outbreaks of Escherichia coli to discussions of the benefits of raw and fermented foods to recent reports of life forms capable of living in extreme environments, the modest microbe has become a figure for thinking through the presents and possible futures of nature, writ large as well as small. Noting that dominant representations of microbial life have shifted from an idiom of peril to one of promise, we argue that microbes - especially when thriving as microbial communities - are being upheld as model ecosystems in a prescriptive sense, as tokens of how organisms and human ecological relations with them could, should, or might be. We do so in reference to two case studies: the regulatory politics of artisanal cheese and the speculative research of astrobiology. To think of and with microbial communities as model ecosystems offers a corrective to the scientific determinisms we detect in some recent calls to attend to the materiality of scientific objects.",
Arsenic,2088423,"Solid-state synthesis, characterization, and biological activity of the bioinorganic complex of aspartic acid and arsenic triiodide Abstract: The bioinorganic complex of aspartic acid and arsenic triiodide was synthesized by a solid-state reaction at room temperature. The formula of the complex is AsI3[HOOCCH2CH(NH2)COOH]2.5. The crystal structure of the complex belongs to monoclinic system with lattice parameters: a=1.0019?nm, b=1.5118?nm, c=2.1971?nm, and beta = 100.28°. The infrared spectra can demonstrate the complex formation between the arsenic ion and aspartic acid, and the complex may be a dimer with bridge structure. The result of primary biological test indicates that the complex possesses better biological activity for the HL-60 cells of the leukemia than arsenic triiodide.",
Arsenic,627587,"Low levels of arsenic trioxide stimulate proliferative signals in primary vascular cells without activating stress effector pathways Abstract: Chronic human exposure to low levels of inorganic arsenic increases the incidence of vascular diseases and specific cancers. Exposure of endothelial cells to environmentally relevant concentrations of arsenic trioxide (arsenite) induces oxidant formation, activates the transcription factor NF-kappaB, and increases DNA synthesis (Barchowsky et al., Free Radic. Biol. Med. 21, 783-790, 1996). We show, in the current study, that arsenite induces concentration-dependent cell proliferation or death in primary porcine aortic endothelial cells. Low concentrations caused cell proliferation and were associated with increased superoxide and H(2)O(2) accumulation, cSrc activity, H(2)O(2)-dependent tyrosine phosphorylation, and NF-kappaB-dependent transcription. These concentrations were insufficient to activate MAP kinases. However, the MAP kinases, extracellular signal-regulated kinase and p38, were activated in response to levels of arsenite that caused cell death. These data suggest that arsenite-induced oxidant accumulation and subsequent activation of tyrosine phosphorylation represent a MAPK-independent pathway for phenotypic change and proliferation in vascular cells. Copyright 1999 Academic Press.",
Arsenic,1328862,"Nitric oxide inhibits DNA-adduct excision in nucleotide excision repair Abstract: Sustained induction of nitric oxide (NO) in chronic inflammation may be mutagenic, through DNA damage induction and/or DNA repair inhibition. Although there is good evidence that NO can cause DNA damage, how NO is involved in DNA repair remains elusive. By using DNA synthesis inhibitors to accumulate DNA strand breaks in comet assay, we show that NO and peroxynitrite inhibit DNA-adduct excision in human fibroblasts damaged by UVC, 4-nitroquinoline 1-oxide, benzo[a]pyrene dihydrodiol epoxide, cisplatin, or mitomycin C, but not with methyl methane sulfonate. Treating cells with arsenite increased NO production and also inhibited the DNA-adduct excision induced by UVC, 4-nitroquinoline 1-oxide, benzo[a]pyrene dihydrodiol epoxide, cisplatin, and mitomycin C, but not by methyl methane sulfonate, H(2)O(2), sodium nitrosoprusside, or 3-morpholinosydnonimine. Arsenite inhibition of DNA-adduct excision was decreased by NO synthase inhibitors and NO scavengers. The nuclear extract prepared from fibroblasts pretreated with sodium nitrosoprusside, dipropylenetriamine NONOate, 3-morpholinosydnonimine, or arsenite also showed decreased activity in excising the DNA adducts induced by UVC and cisplatin but not by methyl methane sulfonate or H(2)O(2) plus Fe. These results are consistent with the notion that NO, peroxynitrite, and arsenite inhibit the DNA-adduct excision in nucleotide excision repair but not that in base excision repair.",
Arsenic,1249005,"Arsenic bioremediation potential of a new arsenite-oxidizing bacterium Stenotrophomonas sp. MM-7 isolated from soil Abstract: A new arsenite-oxidizing bacterium was isolated from a low arsenic-containing (8.8 mg kg(-1)) soil. Phylogenetic analysis based on 16S rRNA gene sequencing indicated that the strain was closely related to Stenotrophomonas panacihumi. Batch experiment results showed that the strain completely oxidized 500 ?M of arsenite to arsenate within 12 h of incubation in a minimal salts medium. The optimum initial pH range for arsenite oxidation was 5-7. The strain was found to tolerate as high as 60 mM arsenite in culture media. The arsenite oxidase gene was amplified by PCR with degenerate primers. The deduced amino acid sequence showed the highest identity (69.1 %) with the molybdenum containing large subunit of arsenite oxidase derived from Bosea sp. Furthermore the amino acids involved in binding the substrate arsenite, were conserved with the arsenite oxidases of other arsenite oxidizing bacteria such as Alcaligenes feacalis and Herminnimonas arsenicoxydans. To our knowledge, this study constitutes the first report on arsenite oxidation using Stenotrophomonas sp. and the strain has great potential for application in arsenic remediation of contaminated water.",
Arsenic,1798804,Erratum: &quot;arsenical association: inorganic arsenic may accumulate in the meat of treated chickens&quot Abstract: ,
Arsenic,1337289,"In utero exposure to arsenic alters lung development and genes related to immune and mucociliary function in mice Abstract: BACKGROUND: Exposure to arsenic via drinking water is a global environmental health problem. In utero exposure to arsenic via drinking water increases the risk of lower respiratory tract infections during infancy and mortality from bronchiectasis in early adulthood. OBJECTIVES: We aimed to investigate how arsenic exposure in early life alters lung development and pathways involved in innate immunity. METHODS: Pregnant BALB/c, C57BL/6 and C3H/HeARC mice were exposed to 0 (control) or 100?g/L arsenic via drinking water from day 8 of gestation until the birth of their offspring. At two weeks post-natal age mice had somatic growth, lung volume and lung mechanics measured. Fixed lungs were utilised for structural analysis. Lung tissue was collected for gene expression analysis by microarray. RESULTS: The response to arsenic was genetically determined and C57BL/6 mice were the most susceptible strain. Arsenic exposed C57BL/6 mice were smaller in size, had smaller lungs and impaired lung mechanics compared with controls. Exposure to arsenic in utero up-regulated the expression of genes in the lung involved in mucous production (Clca3, Muc5b, Scgb3a1), innate immunity (Reg3?, Tff2, Dynlrb2, Lplunc1) and lung morphogenesis (Sox2). Arsenic exposure also induced mucous cell metaplasia and increased expression of CLCA3 protein in the large airways. CONCLUSIONS: Alterations in somatic growth, lung development and the expression of genes involved in mucociliary clearance and innate immunity in the lung are potential mechanisms through which early life arsenic exposure impacts respiratory health.",
Arsenic,628044,"Transformation of human urothelial cells (UROtsa) by as and cd induces the expression of keratin 6a Abstract: BACKGROUND: Cadmium and arsenite can directly and malignantly transform the UROtsa cell line. The tumor heterotransplants produced from these transformed cells have histologic features consistent with human bladder cancer. Previous microarray analysis of total RNA from the parental and transformed cells suggested that keratin 6a was overexpressed as a result of cell transformation. OBJECTIVES: Our goals were to verify overexpression of keratin 6a in Cd(2+)- and As(3+)-transformed UROtsa cells, the corresponding tumor heterotransplants, and human bladder cancer biopsy specimens and to assess what factors may be involved in keratin 6a overexpression. METHODS: Expression was assessed with real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. We used the effect of addition and deletion of potential growth factors in the cell culture growth medium to assess possible pathways used in keratin 6a overexpression. RESULTS: Cd(2+)- and As(3+)-transformed cells grown in serum-containing growth medium, as well as the derived tumor heterotransplants, overexpressed keratin 6a mRNA and protein compared with UROtsa cells grown in serum-containing growth medium. Immunostaining of keratin 6a in tumor heterotransplants showed focal staining of the tumor cells that was localized to the cytoplasm. Focal immunostaining of keratin 6a was also found in some but not all archival patient specimens of high-grade bladder cancer, confirming translation of the results to human bladder cancer. Studies on growth factor deletion and addition indicated that the level of keratin 6a expression was regulated by the presence of both insulin and epidermal growth factor (EGF). In contrast, growth factors had no effect on the elevated levels of keratin 6a expression found in transformed UROtsa cells. CONCLUSIONS: Our present studies suggest that keratin 6a expression may be a biomarker for malignant urothelial cells that possess an activated EGF and or insulin growth factor pathway.",
Arsenic,1337567,"Chronologically matched toenail-Hg to hair-Hg ratio: temporal analysis within the Japanese community (U.S.) Abstract: <strong>UNLABELLED: </strong>ABSTRACT:<br /><br /><strong>BACKGROUND: </strong>Toenail-Hg levels are being used as a marker of methylmercury (MeHg) exposure in efforts to associate exposure with effects such as cardiovascular disease. There is a need to correlate this marker with more established biomarkers that presently underlie existing dose-response relationships in order to compare these relationships across studies.<br /><br /><strong>METHODS: </strong>As part of the Arsenic Mercury Intake Biometric Study, toenail clippings were collected at three time points over a period of one year amongst females from within the population of Japanese living near Puget Sound in Washington State (US). Variability in temporal intra-individual toenail-Hg levels was examined and chronologically matched hair and toenail samples were compared to more accurately define the toxicokinetic variability of Hg levels observed between the two compartments.<br /><br /><strong>RESULTS: </strong>Mean toenail-Hg values (n=43) for the 1st, 2nd and 3rd visits were 0.60, 0.60 and 0.56 ng/mg. Correlations were as follows: r=0.92 between 1st and 2nd clinic visits, r=0.75 between 1st and 3rd visits and r=0.87 between 2nd and 3rd visits. With few exceptions, toenail-Hg values from any visit were within 50-150% of the individual's mean toenail-Hg level. Nearly all participants had less than a two-fold change in toenail-Hg levels across the study period. A regression model of the relationship between toenail-Hg and hair-Hg (n = 41) levels representing the same time period of exposure, gave a slope (Hg ng/mg) of 2.79 for hair relative to toenail (r=0.954).<br /><br /><strong>CONCLUSIONS: </strong>A chronologically matched hair-Hg to toenail-Hg ratio has been identified within a population that consumes fish regularly and in quantity. Intra-individual variation in toenail-Hg levels was less than two-fold and may represent dietary-based fluctuations in body burden for individuals consuming various fish species with different contaminant levels. The chronologically matched ratio will be useful for relating MeHg exposure and dose-response derived from toenail-Hg measurements to those derived from hair-Hg measurements in other studies, and may be useful in future investigations as an indicator of stable MeHg body burden within a population.",
Arsenic,710825,"Arsenic induced progesterone production in a caspase-3 dependent manner and changed redox status in preovulatory granulosa cells Abstract: Arsenic contamination is a principal environmental health threat throughout the world. However, little is known about the effect of arsenic on steroidogenesis in granulosa cells (GCs). We found that the treatment of preovulatory GCs with arsenite stimulated progesterone production. A significant increase in serum level of progesterone was observed in female Sprague-Dawley rats following arsenite treatment at a dose of 10 mg/L/rat/day for 7 days. Further experiments demonstrated that arsenite treatment did not change the level of intracellular cAMP or phosphorylated ERK1/2 in preovulatory GCs; however, progesterone production was significantly decreased when cAMP-dependent protein kinase (PKA) or ERK1/2 pathway was inhibited. This implied that the effect of arsenite on progesterone production may require cAMP/PKA and ERK1/2 signaling but not depend on them. Furthermore, we found that arsenite decreased intracellular reactive oxygen species (ROS) but increased the antioxidant glutathione (GSH) levels and mitochondrial membrane potential (??m) in parallel to the changes in progesterone production. Progesterone antagonist blocked the arsenic-stimulated increase of GSH levels. Arsenite treatment induced caspase-3 activation, although no apoptosis was observed. Inhibition of caspase-3 activity significantly decreased progesterone production stimulated by arsenite or follicle stimulating hormone (FSH). GSH depletion with buthionine sulfoximine (BSO) led to cell apoptosis in response to arsenite treatment. Collectively, this study demonstrated for the first time that arsenite stimulates progesterone production through cleaved/active caspase-3 dependent pathway, and the increase of GSH level promoted by progesterone production may protect GCs against apoptosis and maintain the steroidogenesis of GCs in response to arsenite treatment. © 2011 Wiley Periodicals, Inc.",
Arsenic,1016624,"Carcinogenic metal induced sites of reactive oxygen species formation in hepatocytes Abstract: Severe chronic liver disease results from the hepatic accumulation of copper nickel, cobalt or iron in humans and on the other hand cadmium, dichromate and arsenic may induce lung or kidney cancer. Acute or chronic CdCl2, HgCl2 or dichromate administration induces hepatic and nephrotoxicity in rodents. Oxidative stress is often cited as a possible cause but has not yet been measured. For the first time we have measured the reactive oxygen species (ROS) formation induced when cells are incubated with metals and determined its source. Hepatocytes incubated with 2',7'-dichlorofluorescin diacetate resulted in its rapid uptake and deacetylation by intracellular esterases to form 2',7'-dichlorofluorescin. A marked increase in ROS formation occurred with LD50 concentrations of cadmium [Cd(II)], Hg(II) or arsenite [As(III)] which was released by proton ionophores that uncouple oxidative phosphorylation. Uncouplers or oxidative phosphorylation also inhibited ROS formation induced by these metals, which suggests that mitochondria are major contributors to endogenous ROS formation. Glycolytic substrates also inhibited Cd(II)/Hg(II)/As(III)-induced ROS formation and confirms that mitochondria are the site of ROS formation. By contrast ROS formation by LD50 concentrations of Cu(II), Ni(II), Co(II) or dichromate [Cr(VI)] were not affected by uncouplers or glycolytic substrates. However they were inhibited by lysosomotropic agents or endogenous inhibitors [in contrast to Hg(II), Cd(II) or As(III)]. Furthermore Cu(II), Ni(II), Co(II) or Cr(VI) accumulated in the lysosomes and the ROS formed caused a loss of lysosomal membrane integrity. The release of lysosomal proteases and phospholipases also contributed to hepatocyte cytotoxicity. ROS formation and cytotoxicity induced by added H2O2 or generated by the intracellular redox cycling of nitrofurantoin was also inhibited by lysosomotropic agents and ferric chelators suggesting that lysosomal Fe(II) contributes to H2O2-induced cytotoxicity. In conclusion, lysosomes are sites of cytotoxic ROS formation with redox transition metals (CuII, CrVI, NiII, CoII) whereas mitochondria are the ROS sites for non-redox or poor redox cycling transition metals (CdII, HgII, AsIII).",
Arsenic,1704127,"Posttranslational mechanisms modulating the expression of the cytochrome P450 1A1 gene by methylmercury in HepG2 cells: A role of heme oxygenase-1 Abstract: Recently we demonstrated the ability of mercuric chloride (Hg2+) in human hepatoma HepG2 cells to significantly decrease the TCDD-mediated induction of Cytochrome P450 1A1 (CYP1A1) mRNA, protein, and catalytic activity levels. In this study we investigated the effect of methylmercury (MeHg) on CYP1A1 in HepG2 cells. For this purpose, cells were co-exposed to MeHg and TCDD and the expression of CYP1A1 mRNA, protein, and catalytic activity levels were determined. Our results showed that MeHg did not alter the TCDD-mediated induction of CYP1A1 mRNA, or protein levels; however it was able to significantly decrease CYP1A1 catalytic activity levels in a concentration-dependent manner. Importantly, this inhibition was specific to CYP1A1and was not radiated to other aryl hydrocarbon receptor (AhR)-regulated genes, as MeHg induced NAD(P)H:quinone oxidoreductase 1 mRNA and protein levels. Mechanistically, the inhibitory effect of MeHg on the induction of CYP1A1 coincided with an increase in heme oxygenase-1 (HO-1) mRNA levels. Furthermore, the inhibition of HO-1 activity, by tin mesoporphyrin, caused a complete restoration of MeHg-mediated inhibition of CYP1A1 activity, induced by TCDD. In addition, transfection of HepG2 cells with siRNA targeting the human HO-1 gene reversed the MeHg-mediated inhibition of TCDD-induced CYP1A1. In conclusion, this study demonstrated that MeHg inhibited the TCDD-mediated induction of CYP1A1 through a posttranslational mechanism and confirms the role of HO-1 in a MeHg-mediated effect.",
Arsenic,522223,"Genetic and epigenetic changes induced by chronic low dose exposure to arsenic of mouse testicular Leydig cells Abstract: Arsenic is an important environmental carcinogen that affects millions of people worldwide through contaminated water supplies. Genotoxicity of arsenic has been a topic of controversy. Both genetic alterations (mutations) and epigenetic changes (methylation) have been shown to play a crucial role in environmental carcinogenesis. Chronic exposure to arsenic has been shown to induce malignant transformation of mammalian cells. However, the genetic aberrations induced by arsenic in this process are unclear. The purpose of this study was to determine if both lower (1 pg/ml) and higher concentrations (100 ng/ml) of arsenic induces either mutations or methylation changes that could lead to the development of genomic instability in TM3 cells, immortalized Leydig cells derived from normal mouse testis. Two independent exposure times were used in this study which resulted in cells of 33 and 100 generations in age. Arsenic-induced genetic and epigenetic changes were screened at a genome-wide level by random amplified polymorphic DNA (RAPD), also known as AP-PCR method with undigested DNA as well as DNA digested by the methylation sensitive isosizomeric restriction enzymes MSPI and HpaII and untreated controls. Changes in the DNA fingerprint of both, the restriction enzyme digested DNA (indicating methylation changes) as well as undigested DNA (indicating mutations) from arsenic-treated (low as well as high dose) samples were observed as compared to their controls. Thus, this study provides the first evidence at DNA sequence level for mutagenic potential of arsenic. Further characterization of these altered genomic regions is underway. The understanding of these genetic and epigenetic changes in arsenic-induced carcinogenesis will provide a basis for better interventional approaches in both the treatment and prevention of arsenic-induced cancer.",
Arsenic,1019830,"Low-level arsenite induced gene expression in HEK293 cells Abstract: Chronic, low-level exposure to arsenic frequently results in skin, lung, bladder, and kidney cancer. Since arsenic is primarily excreted via the kidney, this study focused on this target tissue. Gene array was used as a sensitive low-level monitor of the impact of arsenic on this target tissue. Arsenite [As(III)] was chosen as the chemical species of arsenic since As(III) species are touted as the cellular toxic form of arsenic. Human embryonic kidney cell line HEK293 cells were incubated with 1, 10, and 25 microM arsenite [As(III)] for 6 or 24 h. Total RNA from treated and control cells was isolated, reverse transcribed, and labeled with Cy3 or Cy5, and hybridized to a human cDNA microarray. Hybridizations were performed four times using independent total RNA preparations to ensure reproducibility. Raw data from 10 and 25 microM treated cells exposed for 6 h was normalized within, and between, hybridizations followed by identification of genes affected by arsenite exposure based on practical significance (2-fold change up or down) and reproducibility (affected in four of six measurements). In these studies, 20 genes (HMOX1, MT1E, or FOSL1, etc.) were up-regulated, and 19 genes (MYC, JAK1, or CENPE, etc.) were down-regulated. Genes identified at 10 and 25 microM arsenic exposure were then examined after 1 microM treatment for 6 or 24 h. Expression of affected genes showed a dose-dependent (1-25 microM) trend that was apparently not time-dependent (6 vs. 24 h). The affected genes indicate that even this realistic, low-level arsenite exposure was recognized by the HEK293 cells (e.g. metallothionein genes) and produced an oxidative stress (e.g. heme oxygenase gene). These affected genes were characterized as stress response genes, proto-oncogene, signaling molecules, transcription factors, chemokine receptors, proteolytic enzymes, ESTs, and unknown genes. These findings imply that arsenite induces complex cellular injury and the cellular adaptation to As(III) is associated with alterations in the expression of many genes.",
Arsenic,627056,"Classification of heavy-metal toxicity by human DNA microarray analysis Abstract: Microarray technology is proving to be a useful tool to classify undefined environmental toxicants, to investigate underlying mechanisms of toxicity, and to identify candidate toxicant-specific genetic markers by examining global effects of putative toxicants on gene expression profiles. The aim of this study was to evaluate the toxicities of six heavy metals through the comparison with gene expression patterns induced by well-known chemicals. For this purpose, we first identified the genes altered specifically in HepG2 under the exposure of 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), phenol, and N-nitrosodimethylamine (DMN), which were selected as the model chemicals, using DNA microarray. On the basis of the expression profiles of these genes, toxicities of six heavy metals, arsenic, cadmium, nickel, antimony, mercury, and chromium, were evaluated. The specific gene alteration and hierarchical clustering revealed that biological action of six heavy metals was clearly related to that of DMNQ which has been reported to be a reactive oxygen species (ROS) generating chemical and which induced the genes associated with cell proliferative responses. These results suggest that cell proliferative responses which are probably caused by ROS are a major apparent biological action of high-dose heavy metals, supporting the previous reports. Overall, a mechanism-based classification by DNA microarray would be an efficient method for evaluation of toxicities of environmental samples.",
Arsenic,2337107,"Amendment Application in a Multicontaminated Mine Soil: Effects on Trace Element Mobility Abstract: Several amendments were tested for their effectiveness in aiding plant growth and immobilising contaminants in pots containing soil from an arsenopyrite mine contaminated with arsenic and heavy metals and planted with two native grass species, Arrhenatherum elatius subsp. Bulbosum and Festuca curvifolia. Trace element solubility in pore water was monitored using Rhizon samplers for 5 weeks. Results showed that amendments containing ferrous sulphate and ferrous sulphate combined with recycled de-inking paper sludge limited arsenic mobilisation and increased metal solubility. However, ferrous sulphate in combination with calcium carbonate was effective in reducing arsenic and metal solubilisation. Plant biomass of A. elatius was a sensitive indicator of the comparative efficiency of the amendments, although metal(loid) concentration in pore water did not correlate with plant uptake.",
Arsenic,1247866,"Effect of topical dimethylarsinic acid on the expression of apoptosis-related proteins in mouse skin Abstract: We investigated the effect of the topical application of dimethylarsinic acid (DMA) on skin thickness and the expression of several apoptosis-related proteins in skin. After administration of DMA during pregnancy, skin thickness and skin expression of Bcl-2, Bcl-3, Bad, Bid, and caspases-3, -6, -8, -9, and -12 were examined in dams and their offspring. DMA treatment caused significant increases in skin thickness (p &lt; 0.05) and the expression of Bcl-2, Bad, and capase-12 in the skin of dams at the mRNA and protein levels (p &lt; 0.01). However, maternal exposure to DMA did not significantly alter the expression of the studied apoptosis-related factors in the skin of the offspring. These findings indicate that DMA may induce skin apoptosis, in part, by modulating the expression of Bcl-2, Bad, and caspase-12 in maternal skin. Additionally, our results suggest that maternal exposure to DAM during pregnancy may not induce apoptosis in the skin of the offspring.",
Arsenic,1026558,"Effect of arsenic and chromium on the serum amino-transferases activity in Indian major carp, Labeo rohita Abstract: Arsenic and hexavalent chromium toxicity results from their ability to interact with sulfahydryl groups of proteins and enzymes, and to substitute phosphorus in a variety of biochemical reactions. Alanine aminotransferase (ALT; E.C: 2.6.1.2) and Aspartate amino transferase (AST; EC 2.6.1.1) play a crucial role in transamination reactions and can be used as potential biomarkers to indicate hepatotoxicity and cellular damage. While histopathological studies in liver tissue require more time and expertise, simple and reliable biochemical analysis of ALT and AST can be used for a rapid assessment of tissue and cellular damage within 96 h. The main objective of this study was to determine the acute effects of arsenic and hexavalent chromium on the activity of ALT and AST in the Indian major carp, Labeo rohita for 24 h and 96 h. Significant increase in the activity of ALT (P &lt; 0.01) from controls in arsenic exposed fish indicates serious hepatic damage and distress condition to the fish. However, no such significant changes were observed in chromium-exposed fish suggesting that arsenic is more toxic to the fish. These findings indicate that ALT and AST are candidate biomarkers for arsenic-induced hepatotoxicity in Labeo rohita.",
Arsenic,1337769,"Usefulness of the European Epidemic Intelligence Information System in the management of an outbreak of listeriosis, Belgium, 2011 Abstract: A cluster of time-linked cases and the identification of a clonal strain suggest the occurrence of an outbreak of listeriosis in Belgium in 2011, presumably due to the consumption of hard cheese made with pasteurised milk and produced by a Belgium manufacturer. The outbreak clone was identified as Listeria monocytogenes serovar 1/2a, sensitive to arsenic and cadmium and of multilocus sequence typing MLST-type 37. Food investigation of this outbreak was facilitated by the European Epidemic Intelligence Information System and data exchanged between French and Belgium listeriosis surveillance systems.",
Arsenic,1677594,"Geography of non-melanoma skin cancer and ecological associations with environmental risk factors in England Abstract: Background: This study investigates the geography of non-melanoma skin cancer (NMSC) in England, and ecological associations with three widespread environmental hazards: radon, arsenic and ultraviolet radiation from the sun. Methods: Age-/sex-standardised registration rates of NMSC were mapped for local authority (LA) areas (n=326), along with geographical data on bright sunshine, household radon and arsenic. Associations between NMSC and environmental variables, adjusted for socio-economic confounders, were investigated. Results: There was a substantial geographical variation in NMSC rates across English local authorities and between cancer registration regions. Forty percent of variance in rates was at registry region level and 60% at LA level. No association was observed between environmental arsenic and NMSC rates. Rates were associated with area-mean bright sunshine hours. An association with area-mean radon concentration was suggested, although the strength of statistical evidence was sensitive to model specification. Conclusion: The significant geographical variation across England in NMSC registration rate is likely to be partly, but not wholly, explained by registry differences. Findings tentatively support suggestions that environmental radon may be a risk factor for NMSC. Although NMSC is rarely fatal, it has significant implications for individuals and health services, and further research into NMSC geographical and environmental risk factors is warranted.",
Arsenic,2347781,"Arsenate and Dichromate Removal Efficiency of a New Calix[4]arene Impregnated Resin Abstract: This article highlights a newly synthesized 5,11,17,23-tetra-tert. butyl-25,26,27,28-tetrakis(hydrazidecarbonylmethoxy)-calix[4]arene (3) impregnated resin 4 and it's sorption ability for the removal of selected oxoanions, i.e., (arsenate and dichromate) from aqueous environment. Resin 4 was characterized by using FT-IR spectroscopy, scanning electron microscope (SEM), elemental, and thermogravimetic (TGA) analyses techniques. Sorption study was carried out through static and dynamic methods with continuous flow operation to evaluate the potency of resin 4 under various conditions. Several parameters, such as effect of sorbent dosage, contact time, pH, and initial concentration were optimized through batch experiments. Results justify that % sorption of these oxoanions is highly dependent on pH of the solution. Equilibrium was achieved in 45 min, while sorption efficiency of resin 4 can be better explained by Langmuir and Temkin isotherm models. Furthermore, kinetically both oxoanions follow pseudo second order model. Additionally, sorption of arsenate more appropriately could be explained by Moris-Weber diffusion kinetic model. For the dynamic method, Thomas model was used to calculate the kinetic coefficient (k(TH)) and maximum sorption capacity (q(o)) of resin 4 which are 3.84 and 5.94 ml mg(-1) min(-1) and 0.185, 0.160 mg g(-1) for As (V) and Cr (VI) respectively. Furthermore, resin 4 has been found as potential sorbent for removal of these oxoanions from contaminated surface water samples.",
Arsenic,2278041,"Complexes of monocationic group?13 elements with pentaphospha- and pentaarsaferrocene Abstract: Reactions of the sandwich complexes [Cp*Fe(?(5) -E5 )] (Cp*=?(5) -C5 Me5 ; E=P (1), As (2)) with the monovalent Group 13 metals Tl(+) , In(+) , and Ga(+) containing the weakly coordinating anion [TEF] ([TEF]=[Al{OC(CF3 )3 }4 ](-) ) are described. Here, the one-dimensional coordination polymers [M(?,?(5) :?(1) -E5 FeCp*)3 ]n [TEF]n (E=P, M=Tl (3?a), In (3?b), Ga (3?c); E=As, M=Tl (4?a), In (4?b)) are obtained as sole products in good yields. All products were analyzed by single-crystal X-ray diffraction, revealing a similar assembly of the products with ?(5) -bound E5 ligands and very weak ?-interactions between one P or As atom of the ring to the neighbored Group 13 metal cation. By exchanging the [TEF] anion of 4?a for the larger [FAl] anion ([FAl]=[FAl{OC6 F10 (C6 F5 )}3 ](-) ), the coordination compound [Tl{(?(5) -As5 )FeCp*}3 ][FAl] (5) without any ?-interactions of the As5 -ring is obtained. All products are readily soluble in CH2 Cl2 and exhibit a dynamic coordination behavior in solution, which is supported by NMR spectroscopy and ESI-MS spectrometry as well as by osmometric molecular-weight determination. For a better understanding of the proceeding equilibrium DFT calculations of the cationic complexes were performed for the gas phase and in solution. Furthermore, the (31) P{(1) H} magic-angle spinning (MAS) NMR spectra of 3?a-c are presented and the first crystal structure of the starting material 2 was determined.",
Arsenic,627037,"Arsenic-induced DNA-strand breaks associated with DNA--protein crosslinks in human fetal lung fibroblasts Abstract: Sodium arsenite (As)-induced DNA damage was measured in human fetal lung fibroblasts (2BS cells) by an alkaline elution technique and a fluorometric DNA assay. Sodium arsenite at 1-5 microM produced DNA-protein crosslinks, while at 10 microM this effect was not observed. Deproteinization of DNA-protein complexes revealed protein-associated DNA-strand breaks. Both DNA-protein crosslinks and DNA-strand breaks were concentration-dependent; 3 microM As was the most efficient dose. Arsenic mediated DNA-protein interactions may play a major role in arsenic carcinogenesis, and the induced protein-associated DNA-strand breaks could provide an explanation for chromosome aberrations and sister-chromatid exchanges induced by arsenic in vivo and in vitro.",
Arsenic,1240262,"Bioaccumulation of heavy metals in fish species collected from former tin mining catchment Abstract: This study has been carried out to determine the accumulation of heavy metals (arsenic, copper, lead, tin and zinc) in fish samples collected from former tin mining catchment Total eight types of fish family having fifteen different species are identified. Cyperinidae is the most abundant family with eight different species found in the catchment. Fish samples were analysed by using inductively coupled plasma optical emission spectrophotometer ICP-OES. The accuracy of method is validated by certified reference material. The highest level of arsenic was observed in Hampala macrolepidota while Osteochilus hasselti shows the least. For Copper concentrations, the maximum was obtained in Mastacembelus armatus and the minimum in Oxyeleotris marmorata. High levels of lead, tin and zinc were found in the Rasbora elegans, Trichogaster trichopterus, Oxyeleotris marmorata respectively while Macrobrachium resenbergii, Mastacembelus armatus, Rasbora elegans had the least concentrations. The sequence of order of the heavy metals measured was Sn > Pb >Zn > Cu > As, respectively. The results showed elevated levels of tin, led and zinc in all the fish samples although copper and arsenic were available in relatively low concentration in the most samples. Sn, Pb, and Zn concentration in the samples were greater than Malaysia food act permissible levels. Hazard index 1 suggests the probability of adverse health effects. Although the heavy metals analysed in the catchment did not pose any immediate health risk to humans but due to the bioaccumulation and magnification of these heavy metals in humans, it is essential to safeguard levels of the metals in the environment.",
Arsenic,1936076,"Hydrogeochemical factors affecting the mobilization of As into the groundwater of the Brahmaputra alluvial plains of Assam, Northeast India Abstract: Groundwater in the Brahmaputra river basin is known to contain an elevated concentration of naturally occurring Arsenic (As). To better understand the mobilization processes responsible for the As enrichment in the groundwater of the alluvial plains of the Brahmaputra river, the hydrochemical characteristics of the groundwater were studied in two districts, namely the Darrang and Jorhat districts of Assam. A total of 217 groundwater samples were analyzed for 20 water quality parameters. A lower As concentration was observed in the Darrang district with a mean concentration of 0.02 ?g l(-1), while the Jorhat district had a higher As concentration (mean 100 ?g l(-1)). The groundwater in the study areas is characterized by high concentrations of dissolved Fe, Mn, HCO3(-) and PO4(3-) and low concentrations of NO3(-) and SO4(2-). The redox potential and the groundwater composition showed reducing conditions in the groundwater. A difference in the groundwater geochemistry between the two districts was observed and was mainly controlled by the redox conditions in the subsurface, which control the mobility of As in the floodplains. The saturation indices of various As associated minerals were calculated using the geochemical code PHREEQC. The mobilization of As into the groundwater was anticipated to be largely controlled by the reductive dissolution of Fe-oxides and Mn-oxides and partly by competitive anions viz. PO4(3-).",
Arsenic,1508515,"Co-application of selenite and phosphate reduces arsenite uptake in hydroponically grown rice seedlings: Toxicity and defence mechanism Abstract: The study empirically evaluates the abatement of As(III) uptake in rice seedlings (7d), in presence of Se and phosphate (P) under hydroponic condition. Positive correlation between As(III) translocation to the shoots of As(III) and P treated seedlings, shows P dependent As(III) translocation in rice. Whereas, presence of both P (5 and 10?gml-1) and (0.75?gml-1) of Se significantly reduces the As(III) uptake in rice seedlings. Application of Se alone also reduces As(III) uptake both in shoots and roots significantly, however, the seedlings suffers from lipid peroxidation. Among all the studied treatments, lower rates of P (5?gml-1) and Se (0.75?gml-1) when co-applied, significantly reduced As(III) translocation to the shoots without inflicting much toxicity in the seedlings which is manifested as significant increase in biomass with lower thio-barbituric reactive substances (TBARS). Also, significantly lower TBARS in seedlings receiving As(4)+Se(0.75) and higher TBARS in As(4)+Se(1.5), demonstrates that Se applied at lower rates (0.75?gml-1), lowers As induced toxicity. Higher SOD, APX and guaiacol peroxidase (POD) activities in As(4)+P(5)+Se(0.75) compared to that of As(4)+P(5) and As(4)+Se(0.75), supports that lower rate of P and Se provides tolerance towards As induced stress. The nitrogen metabolism in As(4)+P+Se treated seedlings is affected adversely at higher rates of Se and P application. Overall study concluded that application of lower rates of P (5?gml-1) and Se (0.75?gml-1) provides maximum amelioration of As(III) toxicity in rice seedlings.",
Arsenic,903485,"Prenatal exposure to tungsten influences expression of DMBT1, a putative tumor suppressor gene Abstract: We have previously demonstrated that residents of the childhood leukemia clusters of Sierra Vista, Arizona and Fallon, Nevada, are exposed to elevated levels of tungsten and arsenic. The objective of this study is to determine the influence of a prenatal exposure to tungsten and/or arsenic on the expression of DMBT1 in immune tissues. Pregnant C57BL/6 mice were exposed to normalized concentrations of sodium tungstate (Na2O4W.2H2O) in aerosol (0.6mg/L) and water (85.2 µg/L) and/or sodium arsenite (AsNaO2) in aerosol (21 µg/L) and water (3.9 µg/L). Spleen, liver, thymus, and bone marrow were harvested and preserved from 3 and #150;4 week old pups for genomic and proteomic analysis. Changes in DMBT1 expression were associated with tungsten exposure. This suggests that a prenatal exposure to tungsten may increase susceptibility to cancer through a Trp53/DMBT1 pathway.",
Arsenic,2345605,"Concentration and speciation of antimony and arsenic in soil profiles around the world's largest antimony metallurgical area in China Abstract: Mining and smelting activities contribute large amounts of heavy metal pollution to the environment. In this study, four 75- or 80-cm-deep soil profiles in the vicinity of the Xikuangshan Sb smelter were sampled and studied by combination of bulk chemical analysis, sequential extraction procedure, and speciation analysis of Sb and As, which are in order to assess the vertical mobility of metal/metalloid contaminants (Sb, As, Cd, and Hg). The heavy contamination in the soil profiles is mostly located in the uppermost soil layers enriched in organic matter (&lt;40 cm) and exhibited downward migration in the soil profiles. Sb and As, being substantially bound in the exchangeable fractions by sequential extraction studies, showed significant mobility in the profiles. Sb(III), Sb(V), As(III), and As(V) were found in all of the soil samples, and certain methylated states of Sb (TMSb) and As (MMA, DMA) were also present in the lower layer soil samples.",
Arsenic,710797,"Antioxidant and metabolic impairment result in DNA damage in arsenic-exposed individuals with severe dermatological manifestations in Eastern India Abstract: Arsenic is an environmental toxicant, free-radical generator, carcinogenic agent, and aging promoter. Recently, blood samples were analyzed from individuals (control- male 12, female 13; arsenic-exposed- male 16, female 14; and exposed to ?100 ?g/L As, ?10 y) with dermatological symptoms in few affected villages in Eastern India to unravel their hematopoietic, metabolic, and antioxidant profiles. White blood cells recovered from buffy coat were used for DNA fragmentation test. Present observation suggests that significant number of individuals developed pigmentation and palmoplantar hyperkeratosis with black-brownish patch on their body and many of those developed carcinomas. Hematopoietic data show a significant increase in eosinophil and decrease in monocyte count in either sex. Though insignificant, an increase in neutrophil in female and lymphocyte count in male arsenic-exposed individuals are supported by the earlier report on sex dimorphic immune sensitization. Significant increase in serum alanine transaminase in both sexes and bilirubin only in male suggests the eventuality of hepatic disintegration. Arsenic exposure significantly decreased serum amylase in female. A significant decrease in antioxidant components like catalase, soluble thiol, and recently recognized uric acid worsened the situation by generating free radicals as observed in significant rise in malondialdehyde level, which finally increased DNA fragmentation and arsenic-associated mutagenesis and carcinogenesis. This could attribute to lowering in immune competence and related necrotic and/or apoptotic manifestations. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.",
Arsenic,8591,"Study of factors influencing the in vivo methylation of inorganic arsenic in rats Abstract: Previous studies have shown that several factors may influence the methylation of inorganic arsenic by rat liver in vitro (Buchet and Lauwerys, 1985). The present study attempts to assess the relevance of these observations in vivo. Like man, rat inactivates inorganic arsenic by methylation to monomethylarsonic (MMA) and dimethylarsinic (DMA) acids which are excreted in urine along with unchanged inorganic arsenic (Asi). The administration of S-adenosylmethionine alone or in association with reduced (GSH) or oxidized glutathione or acetylcysteine and the increase of hepatic GSH level by butylated hydroxytoluene pretreatment do not stimulate the urinary excretion of the methylated arsenic metabolites following a challenge dose of inorganic arsenic. Conversely a reduction of the hepatic GSH level by phorone pretreatment greatly modifies the metabolism of inorganic arsenic in vivo. A reduction exceeding 90% of the control value leads to a decreased urinary excretion of MMA and DMA and an increased urinary excretion of inorganic arsenic. This is also associated with an increased accumulation of inorganic arsenic in the liver. This suggests that a drastic reduction of GSH level in liver not only impairs the methylation of inorganic arsenic but also impairs its biliary excretion. When GSH depletion is less severe, the total amount of arsenic excreted in urine after a challenge dose of NaAsO2 is not significantly different from that found in unpretreated animals but the proportion of the three metabolic forms is different: MMA is reduced whereas Asi and DMA tend to increase. These changes resemble those found in patients with liver insufficiency (J.P. Buchet, A. Geubel, S. Pauwels, P. Mahieu, and R. Lauwerys (1984). The influence of liver disease on the methylation of arsenite in humans. Arch. Toxicol. 55, 151-154). Long-term pretreatment of rats with CCl4 slightly reduces the amount of MMA and DMA excreted in urine following a challenge dose of inorganic arsenic. This effect may result from a reduction of GSH transferase activity by CCl4. This study demonstrates the important role of liver GSH in the metabolism of inorganic arsenic in vivo.",
Arsenic,2347643,"Effect of CaO on retention of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W and Pb in bottom ashes from fluidized-bed coal combustion power station Abstract: This work was conducted to evaluate whether Ca-bearing additives used during coal combustion can also help with the retention of some other elements. This work was focused on the evaluation of bottom ashes collected during four full-scale combustion tests at an operating thermal fluidized-bed power station. Bottom ashes were preferred to fly ashes for the study to avoid interference from condensation processes usually occurring in the post-combustion zone. This work focused on the behaviors of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W, and Pb. Strong positive correlations with CaO content in bottom ashes were observed (for all four combustion tests) for S, As, Cl and Br (R=0.917-0.999). Strong inverse proportionality was calculated between the contents of Pb, Zn, Ni, Cr and Mn and CaO, so these elements showed association to materials other than Ca-bearing compounds (e.g., to aluminosilicates, organic matter, etc.). Somewhat unclear behaviors were observed for W, Cu, and V. Their correlation coefficients were evaluated as statistically not significant, i.e., these elements were not thought to be significantly associated with CaO. It was also discovered that major enrichment of CaO in the finest bottom ash fractions could be advantageously used for simple separation of elements strongly associated with these fractions, mainly S and As, but also Cl or Br. Removal of 5% of the finest ash particles brings about a decrease in As concentration down to 77%-80% of its original bulk ash content, which can be conveniently used e.g., when high As content complicates further ash utilization.",
Arsenic,1024072,"Endemic arsenosis caused by indoor combustion of high-As coal in Guizhou Province, P.R. China Abstract: The arsenic (As) content of coal relating with mineralization of gold in Southwest Guizhou Province, China is up to 35,000 ppm. The coal is burned indoors in open pits for daily cooking and crop drying. As a result, arsenic is precipitated and concentrated in corn (5-20 ppm), chili (100-800 ppm) and other foods. Arsenic concentrations in the drinking water of high-As coal areas are lower than 50 ppb. The estimated main sources of As exposure in this area are from polluted food. Approximately, 3000 arsenosis patients were found by 1998, and more than 100,000 people from six counties were under the threat in China. This paper presents the major ingestion pathway of this type arsenosis and relative geochemistry of high-As coal.",
Arsenic,1704139,"Arsenic Resistance and Bioaccumulation of an Indigenous Bacterium Isolated from Aquifer Sediments of Datong Basin, Northern China Abstract: ",
Arsenic,1030811,"Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer) Abstract: Analyses of arsenic (As) species in tissues and body fluids of individuals chronically exposed to inorganic arsenic (iAs) provide essential information about the exposure level and pattern of iAs metabolism. We have previously described an oxidation state-specific analysis of As species in biological matrices by hydride-generation atomic absorption spectrometry (HG-AAS), using cryotrapping (CT) for preconcentration and separation of arsines. To improve performance and detection limits of the method, HG and CT steps are automated and a conventional flame-in-tube atomizer replaced with a recently developed multiple microflame quartz tube atomizer (multiatomizer). In this system, arsines from As(III)-species are generated in a mixture of Tris-HCl (pH 6) and sodium borohydride. For generation of arsines from both As(III)- and As(V)-species, samples are pretreated with L-cysteine. Under these conditions, dimethylthioarsinic acid, a newly described metabolite of iAs, does not interfere significantly with detection and quantification of methylated trivalent arsenicals. Analytical performance of the automated HG-CT-AAS was characterized by analyses of cultured cells and mouse tissues that contained mono- and dimethylated metabolites of iAs. The capacity to detect methylated As(III)- and As(V)-species was verified, using an in vitro methylation system containing recombinant rat arsenic (+3 oxidation state) methyltransferase and cultured rat hepatocytes treated with iAs. Compared with the previous HG-CT-AAS design, detection limits for iAs and its metabolites have improved significantly with the current system, ranging from 8 to 20 pg. Recoveries of As were between 78 and 117%. The precision of the method was better than 5% for all biological matrices examined. Thus, the automated HG-CT-AAS system provides an effective and sensitive tool for analysis of all major human metabolites of iAs in complex biological matrices.",
Arsenic,1355017,"Study on the application of gibberellin for the spectrophotometric determination of arsenic, phosphorus, silicon and germanium(R) Abstract: ",
Arsenic,1033498,"Vinyl chloride-induced hepatic angiosarcoma Abstract: In early 1974, an alert plant physician reported the occurrence of several cases of the otherwise rare hepatic angiosarcoma (HAS) at a single polyvinyl chloride (PVC) production facility in Louisville, Kentucky (U.S.A.). Upon further investigation, the relative risk for HAS at this plant appeared to be approximately 5,000, strongly indicating a causal relationship with some factor at the plant. Epidemiologic studies at this and other PVC polymerization plants identified vinyl chloride monomer (VCM) as the causative agent. Experimental studies reported in early 1974 confirmed VCM as a hepatic carcinogen capable of producing HAS and other tumors. Follow-up epidemiologic studies revealed that: 1) HAS is the end stage of a progressive liver disease consisting of hepatocytic and sinusoidal cell hyperplasia, sinusoidal dilatation, and hepatic fibrosis; 2) over 100 cases of VCM-induced HAS have occurred worldwide; and 3) an increased risk of lung cancer has been reported in some cohort studies of PVC polymerization workers, although this outcome may be related to PVC dust or factors other than VCM. A national study of HAS in the United States identified 3 other causes of HAS: Thorotrast, inorganic arsenic, and androgenic-anabolic steroids. Of 168 cases found to occur during 1964 through 1974, 42 cases (25%) were associated with the 4 known etiologic agents, while 126 cases (75%) were of unknown etiology.",
Arsenic,1519219,"Exploratory biomonitoring study among workers of livestock farms of the Taranto Province Abstract: <strong>OBJECTIVE: </strong>to conduct a survey on blood levels of metals and organochlorine compounds (dioxins and PCBs) among workers of livestock farms, and to identify the factors able to explain the magnitude and variability of the measured concentrations.<br /><br /><strong>DESIGN: </strong>exploratory human biomonitoring study.<br /><br /><strong>SETTING AND PARTICIPANTS: </strong>a sample of 45 workers from farms (masserie) located in the Province of Taranto was included in the study. The farms, located between 6 and 43 km from the industrial area, are family owned and animals (mainly sheep and goats) are locally reared outdoors. The study subjects have similar eating habits, including food consumption resulting from their production.<br /><br /><strong>RESULTS: </strong>manganese concentrations and, to a lesser extent, arsenic, cadmium and lead are in the medium-high range of levels observed in the Italian general population. This study does not identify factors able to explain the variability in the blood levels of metals. The amount of dioxins and PCBs, on the other hand, is strongly associated both with subjects age and the distance of farm from the industrial site.<br /><br /><strong>CONCLUSION: </strong>the results of this survey are suggestive of research hypotheses that need to be confirmed by biomonitoring studies of adequate design and size, in particular the hypothesis that the blood level of dioxins and PCBs decreases with increasing distance from the industrial site. We recommend ad hoc studies to better characterize the exposure of farmers (also associated with agricultural activities), and of the inhabitants of Taranto, to environmental persistent pollutants, also in terms of food matrices locally produced and consumed.",
Arsenic,1677289,"Influence of soil properties and phosphate addition on arsenic uptake from polluted soils by velvetgrass (Holcus lanatus) Abstract: Four kinds of soil material were used in a pot experiment with velvetgrass (Holcus lanatus). Two unpolluted soils: sand (S) and loam (L) were spiked with sodium arsenite (As II) and arsenate (As V), to obtain total arsenic (As) concentrations of 500 mg As kg(-1). Two other soils (ZS I, ZS III), containing 3320 and 5350 mg As kg(-1), were collected from Zloty Stok where gold and arsenic ores were mined and processed for several centuries. The effects of phosphate addition on plants growth and As uptake were investigated. Phosphate was applied to soils in the form of NH4H2PO4 at the rate 0.2 g P/kg. Average concentrations of arsenic in the shoots of velvetgrass grown in spiked soils S and L without P amendment were in the range 18-210 mg As kg(-1) d.wt., whereas those in plants grown on ZS I and ZS II soils were considerably lower, and varied in the range 11-52 mg As kg(-1) d.wt. The addition of phosphate caused a significant increase in plant biomass and therefore the total amounts of As taken up by plants, however, the differences in As concentrations in the shoots of velvetgrass amended and non-amended with phosphate were not statistically significant.",
Arsenic,1519188,Reduction in Bioavailability of Arsenic in Contaminated Irrigated Soil using Zinc and Organic Manure Abstract: ,
Arsenic,1378488,"Arsenic species in groundwaters of the blackfoot disease area, Taiwan Abstract: BIOSIS COPYRIGHT: BIOL ABS. The groundwaters collected from three wells in the Blackfoot disease (BFD) area in southwest Taiwan contain, on the average, 671 | 149 mug of total dissolved arsenic. The arsenic contents in the well waters of Hsinchu, a city in the northwest of the island where no BFD has ever been reported, are less than 0.7 mug/L. The predominant arsenic species in the well waters of the BFD area is As3+ with an average As3+/As5+ ratio of 2.6. The methyl arsenicals, monomethylarsinic acid and dimethylarsonic acid, are below detection limits (<1 mug/L), and the insoluble suspended arsenic accounts for about 3% of the total arsenic in the water. Ultrafiltration experiments indicate that the dissolved arsenic species can be roughly divided into two main groups, one with molecular mass <1000 and the other with molecular mass300 000 Da. The results obtained from the BFD area are compared with similar arsenic studies conducted in the United States. The importance of arsenic spe",
Arsenic,2298730,"A Ternary Age-Mixing Model to Explain Contaminant Occurrence in a Deep Supply Well Abstract: The age distribution of water from a public-supply well in a deep alluvial aquifer was estimated and used to help explain arsenic variability in the water. The age distribution was computed using a ternary mixing model that combines three lumped parameter models of advection-dispersion transport of environmental tracers, which represent relatively recent recharge (post-1950s) containing volatile organic compounds (VOCs), old intermediate depth groundwater (about 6500 years) that was free of drinking-water contaminants, and very old, deep groundwater (more than 21,000 years) containing arsenic above the USEPA maximum contaminant level of 10?µg/L. The ternary mixing model was calibrated to tritium, chloroflorocarbon-113, and carbon-14 ((14) C) concentrations that were measured in water samples collected on multiple occasions. Variability in atmospheric (14) C over the past 50,000 years was accounted for in the interpretation of (14) C as a tracer. Calibrated ternary models indicate the fraction of deep, very old groundwater entering the well varies substantially throughout the year and was highest following long periods of nonoperation or infrequent operation, which occured during the winter season when water demand was low. The fraction of young water entering the well was about 11% during the summer when pumping peaked to meet water demand and about 3% to 6% during the winter months. This paper demonstrates how collection of multiple tracers can be used in combination with simplified models of fluid flow to estimate the age distribution and thus fraction of contaminated groundwater reaching a supply well under different pumping conditions.",
Arsenic,1016289,"A mouse model for the study of vascular permeability changes induced by arsenic Abstract: The primary objective of our present research was to develop an animal model for the investigation of arsenic-induced vasculopathy. Epidemiological evidence indicated that, aside from cancer, cardiovascular-related diseases were probably the most prominent health concerns in arseniasis areas. Although there were many investigations on the effect of arsenic on endothelial cells, most of these studies were conducted under in vitro conditions. A good animal model for studying the effects of arsenic on vascular integrity in vivo is very much needed. We have previously developed a rat model that could be used to demonstrate vascular changes induced by arsenic in vivo. In the present report, we are introducing a new model that is even more sensitive, economical, and effective than our original rat model. Taking advantage of the characteristics of mouse ears (thin, delicate, and with easily visible blood vessels), we demonstrated the pattern and extent of vascular leakage induced by arsenic clearly, quantitatively and convincingly. With this model, we demonstrated a time-dependent increase in vascular permeability induced by arsenic (a fourfold increase in vascular leakage was observed between 10-60 minutes). With this model, we were also able to demonstrate that small caliber vessels were more vulnerable than vessels of larger caliber. Thus, this animal model can provide dynamic information (from toxic effects, pathology, and functional alterations to cellular/molecular mechanisms) that cell culture techniques are unable to provide. The introduction of this model hopefully will stimulate and inspire many other new in vivo investigations on vasculopathy induced by arsenic or other chemicals in the future.",
Arsenic,1519198,"Assessment of an Increase in Boron and Arsenic Concentrations at the Discharge Area of Na-Borate Mine (Kirka-Eskisehir, Turkey) Abstract: ",
Arsenic,1022093,"Arsenic levels in the soil and risk of birth defects: A population-based case-control study using GIS technology Abstract: Arsenic is a highly dangerous metal that has been linked to a number of adverse health effects in both adults and children, including birth defects. Yet few epidemiologic studies have examined the relationship between arsenic levels in the soil and the risk of birth defects. The purpose of the authors' study was to examine this association among people exposed to environmental pollution in a developed area of China. The authors used global positioning system to locate the coordinates of 80 villages in 40 towns for soil sampling. Soil samples were analyzed for arsenic content. Logistic regression was used to investigate the relationship between exposure to arsenic and birth defects, controlling for potentially confounding factors. The authors found that exposure to arsenic in any amount increased the risk of birth defects. The positive association found between arsenic exposure and birth defects warrants further study, and future large-scale population-based studies are needed with an emphasis on individual-level exposure and confounding variables.",
Arsenic,2064290,"Combined NanoSIMS and synchrotron X-ray fluorescence reveal distinct cellular and subcellular distribution patterns of trace elements in rice tissues Abstract: The cellular and subcellular distributions of trace elements can provide important clues to understanding how the elements are transported and stored in plant cells, but mapping their distributions is a challenging task. The distributions of arsenic, iron, zinc, manganese and copper, as well as physiologically related macro-elements, were mapped in the node, internode and leaf sheath of rice (Oryza sativa) using synchrotron X-ray fluorescence (S-XRF) and high-resolution secondary ion mass spectrometry (NanoSIMS). Although copper and silicon generally showed cell wall localization, arsenic, iron and zinc were strongly localized in the vacuoles of specific cell types. Arsenic was highly localized in the companion cell vacuoles of the phloem in all vascular bundles, showing a strong co-localization with sulfur, consistent with As(III)-thiol complexation. Within the node, zinc was localized in the vacuoles of the parenchyma cell bridge bordering the enlarged and diffuse vascular bundles, whereas iron and manganese were localized in the fundamental parenchyma cells, with iron being strongly co-localized with phosphorus in the vacuoles. The highly heterogeneous and contrasting distribution patterns of these elements imply different transport activities and/or storage capacities among different cell types. Sequestration of arsenic in companion cell vacuoles may explain the limited phloem mobility of arsenite.",
Arsenic,1018230,"Arsenic contamination of ground water and its health impact on population of district of Nadia, West Bengal, India Abstract: <strong>BACKGROUND: </strong>The global health impact and disease burden due to chronic arsenic toxicity has not been well studied in West Bengal.<br /><br /><strong>OBJECTIVE: </strong>To ascertain these, a scientific epidemiological study was carried out in a district of the state.<br /><br /><strong>MATERIALS AND METHODS: </strong>Epidemiological study was carried out by house-to-house survey of arsenic affected villages in the district of Nadia. A stratified multi-stage design has been adopted for this survey for the selection of the participants. A total number of 2297 households of 37 arsenic affected villages in all the 17 blocks were surveyed in the district.<br /><br /><strong>RESULT: </strong>Out of 10469 participants examined, prevalence rate of arsenicosis was found to be 15.43%. Out of 0.84 million people suspected to be exposed to arsenic, 0.14 million people are estimated to be suffering from arsenicosis in the district. Highest level of arsenic in drinking water sources was found to be 1362 ?g/l, and in 23% cases it was above 100 ?g/l. Majority of the population living in the arsenic affected villages were of low socio-economic condition, inadequate education and were farmers or doing physical labour. Chronic lung disease was found in 207 (12.81%) subjects among cases and 69 (0.78%) in controls. Peripheral neuropathy was found in 257 (15.9%) cases and 136 (1.5%) controls.<br /><br /><strong>CONCLUSION: </strong>Large number of people in the district of Nadia are showing arsenical skin lesion. However, insufficient education, poverty, lack of awareness and ineffective health care support are major factors causing immense plight to severely arsenic affected people.",
Arsenic,184486,"Use of inductively coupled plasma-atomic emission spectroscopy (ICP-AES) in screening for trace metal exposures in an industrial population Abstract: A heterogeneous group of asymptomatic industrial workers potentially exposed to various toxic metals was screened for trace metal exposure. Each was examined and then completed an occupational health history questionnaire and had hair and blood samples analyzed for 10 metals via the inductively coupled plasma-atomic emission spectroscopy technique. No industrial hygiene survey was performed. The concentrations of trace elements found in our cohort were comparable to previously published levels for nonoccupationally exposed groups. This finding is not unexpected in light of the nature of the population studied and the screening technique. The levels in blood and hair were not well correlated, and subsets of the population with high metal burdens could not be identified on the basis of self-reported occupational exposure histories.",
Arsenic,627182,"Arsenic in drinking-water and reproductive health outcomes: A study of participants in the Bangladesh integrated nutrition programme Abstract: This study examined 2,006 pregnant women chronically exposed to a range of naturally-occurring concentrations of arsenic in drinking-water in three upazilas in Bangladesh to find out relationships between arsenic exposure and selected reproductive health outcomes. While there was a small but statistically significant association between arsenic exposure and birth-defects (odds ratio=1.005, 95% confidence interval 1.001-1.010), other outcomes, such as stillbirth, low birth-weight, childhood stunting, and childhood under-weight, were not associated with arsenic exposure. It is possible that the association between arsenic exposure from drinking-water and birth-defects may be a statistical anomaly due to the small number of birth-defects observed. Future studies should look more closely at birth-defects, especially neural tube defects, to elucidate any potential health effects associated with arsenic exposure from drinking-water. Further, given the knowledge that serious health effects can result from chronic arsenic exposure, efforts to find alternatives of safe drinking-water for the population must continue.",
Arsenic,1027373,"Contributions of reactive oxygen species and mitogen-activated protein kinase signaling in arsenite-stimulated hemeoxygenase-1 production Abstract: Hemeoxygenase-1 (HO-1) is an oxidative stress responsive gene upregulated by various physiological and exogenous stimuli. HO-1 has cytoprotective activities and arsenite is a potent inducer of HO-1 in many cell types and tissues, including epidermal keratinocytes. We investigated the potential contributions of reactive oxygen species (ROS) generation and mitogen-activated protein kinase (MAPK) activation to arsenite-dependent regulation of HO-1 in HaCaT cells, an immortalized human keratinocyte line. Both epidermal growth factor (EGF) and arsenite stimulated ROS production was detected by dihydroethidium (DHE) staining and fluorescence microscopy. Arsenite induced HO-1 in a time- and concentration-dependent manner, while HO-1 expression in response to EGF was modest and evident at extended time points (48-72 h). Inhibition of EGF receptor, MEK I/II or Src decreased arsenite-stimulated HO-1 expression by 20-30%. In contrast, addition of a superoxide scavenger or inhibition of p38 activity decreased the arsenite-dependent response by 80-90% suggesting that ROS and p38 are required for HO-1 induction. However, ROS generation alone was insufficient for the observed arsenite-dependent response as use of a xanthine/xanthine oxidase system to generate ROS did not produce an equivalent upregulation of HO-1. Cooperation between ERK signaling and ROS generation was demonstrated by synergistic induction of HO-1 in cells co-treated with EGF and xanthine/xanthine oxidase resulting in a response nearly equivalent to that observed with arsenite. These findings suggest that the ERK/MAPK activation is necessary but not sufficient for optimal arsenite-stimulated HO-1 induction. The robust and persistent upregulation of HO-1 may have a role in cellular adaptation to chronic arsenic exposure.",
Arsenic,656801,"Mutational spectrum of p53 gene in arsenic-related skin cancers from the blackfoot disease endemic area of Taiwan Abstract: To understand the role of p53 tumour suppressor gene in the carcinogenesis of arsenic-related skin cancers from the blackfoot disease endemic area of Taiwan, we collected tumour samples from 23 patients with Bowen's disease, seven patients with basal cell carcinomas (BCC) and nine patients with squamous cell carcinomas (SCC). The result showed that p53 gene mutations were found in 39% of cases with Bowen's disease (9/23), 28.6% of cases with BCC (2/7) and 55.6% of cases with SCC (5/9). Most of the mutation sites were located on exon 5 and exon 8. Moreover, the results from direct sequencing indicated that missense mutations were found at codon 149 (C-->T) in one case, codon 175 (G-->A) in three cases, codon 273 (G-->C) in three cases, codon 292 (T-->A) in one case, codon 283 (G-->T) in one case, codon 172 (T-->C) in one case and codon 284 (C-->A) in one case. In addition, silent mutations were also found in four cases. These mutations were located at codons 174, 253, 289 and 298 respectively. In immunohistochemistry analysis, p53 overexpression was found in 43.5% (10/23) of cases with Bowen's disease, 14% (1/7) of cases with BCC and 44% (4/9) of cases with SSC. These findings showed that p53 gene mutation rate in arsenic-related skin cancers from the blackfoot disease endemic area of Taiwan is high and that the mutation types are different from those in UV-induced skin cancers.",
Arsenic,1377944,"Arsenite Synergistically Increases UV-Induced Oxidative DNA Damage In Human Keratinocyte By Inhibitingthe Activity Of PARP-1 Abstract: Inorganic arsenic is a known human carcinogens. Recent reports demonstrate that arsenite could act as a co-carcinogen to enhance UV-induced skin cancer. We hypothesize that the inhibition of DNA damage repair by arsenite maybe an important pathway in the observed increase in tumor occurrence. Using 8-OHdG as a biomarker, we have investigated the effect of arsenite on UV-induced oxidative DNA damage in human keratinocytes. Our results show that low concentration of arsenite (2 uM), which did not induce detectable change in 8-OHdG generation by itself, synergistically increased the 8-OHdG level induced by UV irradiation, which became apparent 30 min after UV exposure. To determine the potential mechanism, we focused on the poly (ADP-ribose) polymerase-1 (PARP-1), a zincfinger protein that plays an important role in DNA base excision repair. Using immunoflurescence method to detect the PARP-1 activity, we found that arsenite inhibited UV-induced PARP-1 activation in a concentration-dependent manner, with concomitant increase in 8-OHdG generation. Furthermore, treating cells with PARP-1 inhibitor (3-AB) produced very similar results, indicating that arsenite acted like a PARP-1 inhibitor. Since the zinc-finger motif of PARP-1 is essential for its binding to damaged DNA, we added Zn(II) to the arsenite-treated keratinocytes. The addition of Zn(II) abolished the enhancement of arsenite on UVinduced 8-OHdG generation, and restored PARP-1 activity in a Zn(II) concentration- dependent manner, indicating that the inhibition of PARP-1 by arsenite may involve competing of As(III) with Zn(II) for the position in the zinc-finger motif. In conclusion, our data showed that arsenite acted as a co-carcinogen in UV induced skin cancer by inhibiting base excision repair. Inhibition of PARP-1 activity by interfering with its zinc finger motif is likely an underlying molecular mechanism. These results are the first demonstration of arsenite?s synergistic effect in UV induced oxidative DNA damage in human cells.",
Arsenic,1023231,"Cancer mortality during the 1968-1994 period in a mining area in France Abstract: We performed a geographical analysis of cancer mortality in the communes surrounding an industrial mining complex (Salsigne, France) where suspicious levels of pollution due to arsenic were measured. Compared with that observed in a control area, we showed a significant excess of mortality due to all cancer types (ratio of standard mortality ratios (ratio of SMRs)=1.1), lung cancer (ratio of SMRs=1.8), pharynx cancer (ratio of SMRs=2.1) in the whole population, and due to digestive system cancer (ratio of SMRs=1.3) among women. The results were similar after controlling for the occupation distribution in the populations. Excluding mining complex workers deaths from the deaths in the studied populations did not modify the pattern of our results. We concluded that the excess of cancer deaths could not be exclusively due to potential professional exposures among the workers of the mining complex and are probably explained by environmental contamination.",
Arsenic,1508560,"Acute arsenic treatment alters cytochrome P450 expression and arachidonic acid metabolism in lung, liver and kidney of C57Bl/6 mice Abstract: 1.?Arsenic (As(III)) toxicity has received increasing attention as human exposure to arsenic is associated with pulmonary, hepatic and renal toxicities. Therefore, in the present study, we investigated the effect of acute As(III) treatment on pulmonary, hepatic and renal cytochrome (CYP) P450-mediated arachidonic acid metabolism. 2.?Our results demonstrated that acute As(III) treatment (12.5?mg/kg) altered CYP epoxygenases, CYP ?-hydroxylases and EPHX2 mRNA levels that were isozyme and tissue specific. 3.?Furthermore, As(III) increased the formation of epoxyeicosatrienoic acids (EETs) in the kidney without affecting their levels in the lung or liver. In addition, acute As(III) treatment increased dihydroxyeicosatrienoic acid (DHETs) formation in the lung, while it did not affect liver DHETs formation and decreased kidney DHETs formation. 4.?As(III) also increased total epoxygenases activity in the lung while it decreased its levels in the kidney and had no effect on the liver. Furthermore, As(III) increased 20-hydroxyeicosatetraenoic acid formation in the liver while it decreased its formation in the kidney. 5.?Lastly, As(III) increased soluble epoxide hydrolase activity in the lung, while it decreased its levels in the kidney and had no effect on the liver. In conclusion, this is the first demonstration that As(III) alters arachidonic acid metabolism in a tissue specific manner.",
Arsenic,1354121,Designing Cropping Systems for Metal-Contaminated Sites: A Review Abstract: ,
Arsenic,1337470,"Involvement of Nrf2 activation in the upregulation of S100A9 by exposure to inorganic arsenite Abstract: This study examined whether S100A8 and S100A9, which comprise a complex called calprotectin, are upregulated by exposure to sodium arsenite [As(III)] in nine lines of human-derived cells. HaCaT skin keratinocyte cells, U937 leukemic monocyte cells, and UROtsa urothelial cells showed increased mRNA levels of S100A8 and S100A9 after a 2-week exposure to As(III). To understand the mechanisms regulating S100A9 upregulation in response to As(III), we tested S100A9 promoter-dependent luciferase activity in HaCaT cells transfected with S100A9 promoter (-1000/+429)-fused luciferase cDNA. The results indicated that exposure to As(III) stimulated S100A9 promoter-dependent luciferase activity. In addition, the transcription NF-E2-related factor 2 (Nrf2) was strongly activated in HaCaT cells exposed to As(III). Since two putative antioxidant response elements were found in the S100A9 promoter (ARE1, 5'-ACAGGCAGGG-3' from -897 to -887; ARE2, 5'-ATCTTCCGGAG-3' from -78 to -67), we constructed deletion mutants of each ARE on S100A9 promoter-fused luciferase cDNA. The results indicated that ARE2 is the responsible element for the activation of S100A9 transcription in response to As(III). This report is the first to demonstrate that As(III) enhanced S100A8 and S100A9 expression in human-derived cells and As(III)-induced S100A9 expression is dependent on Nrf2 activation.",
Arsenic,1034262,"Industrial hygiene and control technology assessment of ion implantation operations Abstract: Ion implantation is a process used to create the functional units (pn junctions) of integrated circuits, photovoltaic (solar) cells and other semiconductor devices. During the process, ions of an impurity or a &quot;dopant&quot; material are created, accelerated and imbedded in wafers of silicon. Workers responsible for implantation equipment are believed to be at risk from exposure to both chemical (dopant compounds) and physical (ionizing radiation) agents. In an effort to characterize the chemical exposures, monitoring for chemical hazards was conducted near eleven ion implanters at three integrated circuit facilities, while ionizing radiation was monitored near four of these units at two of the facilities. The workplace monitoring suggests that ion implantation operators routinely are exposed to low-level concentrations of dopants. Although the exact nature of dopant compounds released to the work environment was not determined, area and personal samples taken during normal operating activities found concentrations of arsenic, boron and phosphorous below OSHA Permissible Exposure Limits (PELs) for related compounds; area samples collected during implanter maintenance activities suggest that a potential exists for more serious exposures. The results of badge dosimetry monitoring for ionizing radiation indicate that serious exposures are unlikely to occur while engineering controls remain intact. All emissions were detected at levels unlikely to result in exposures above the OSHA standard for the whole body (1.25 rems per calendar quarter). The success of existing controls in preventing worker exposures is discussed. Particular emphasis is given to the differential exposures likely to be experienced by operators and maintenance personnel.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,1070394,"Barium inhibits arsenic-mediated apoptotic cell death in human squamous cell carcinoma cells Abstract: Our fieldwork showed more than 1 ?M (145.1 ?g/L) barium in about 3 ?M (210.7 ?g/L) arsenic-polluted drinking well water (n = 72) in cancer-prone areas in Bangladesh, while the mean concentrations of nine other elements in the water were less than 3 ?g/L. The types of cancer include squamous cell carcinomas (SCC). We hypothesized that barium modulates arsenic-mediated biological effects, and we examined the effect of barium (1 ?M) on arsenic (3 ?M)-mediated apoptotic cell death of human HSC-5 and A431 SCC cells in vitro. Arsenic promoted SCC apoptosis with increased reactive oxygen species (ROS) production and JNK1/2 and caspase-3 activation (apoptotic pathway). In contrast, arsenic also inhibited SCC apoptosis with increased NF-?B activity and X-linked inhibitor of apoptosis protein (XIAP) expression level and decreased JNK activity (antiapoptotic pathway). These results suggest that arsenic bidirectionally promotes apoptotic and antiapoptotic pathways in SCC cells. Interestingly, barium in the presence of arsenic increased NF-?B activity and XIAP expression and decreased JNK activity without affecting ROS production, resulting in the inhibition of the arsenic-mediated apoptotic pathway. Since the anticancer effect of arsenic is mainly dependent on cancer apoptosis, barium-mediated inhibition of arsenic-induced apoptosis may promote progression of SCC in patients in Bangladesh who keep drinking barium and arsenic-polluted water after the development of cancer. Thus, we newly showed that barium in the presence of arsenic might inhibit arsenic-mediated cancer apoptosis with the modulation of the balance between arsenic-mediated promotive and suppressive apoptotic pathways.",
Arsenic,627902,"Arsenic exposure from drinking-water and carotid artery intima-medial thickness in healthy young adults in Bangladesh Abstract: Epidemiological studies have linked high levels (>200 microg/L) of chronic exposure to arsenic in drinking-water with elevated risks of several vascular diseases. In this pilot study, the association between low-level arsenic exposure and carotid artery intimal-medial thickness (IMT) was evaluated among 66 healthy, normotensive, relatively young individuals (mean age 35 years) participating in the ongoing Health Effects of Arsenic Longitudinal Study in Bangladesh. Participants with a higher carotid IMT (>0.75 mm) in general had higher levels of past chronic exposure of arsenic than those with a lower carotid IMT (< or = 0.75 mm). Although the differences in average arsenic exposure between the two groups were not statistically significant, the findings suggest a possible association between low-level arsenic exposure from drinking-water and carotid atherosclerosis, warranting the need for larger studies.",
Arsenic,2347778,"Determination of Mineral, Trace Element, and Pesticide Levels in Honey Samples Originating from Different Regions of Malaysia Compared to Manuka Honey Abstract: The present study was undertaken to determine the content of six minerals, five trace elements, and ten pesticide residues in honeys originating from different regions of Malaysia. Calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) were analyzed by flame atomic absorption spectrometry (FAAS), while sodium (Na) and potassium (K) were analyzed by flame emission spectrometry (FAES). Trace elements such as arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and cobalt (Co) were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) following the microwave digestion of honey. High mineral contents were observed in the investigated honeys with K, Na, Ca, and Fe being the most abundant elements (mean concentrations of 1349.34, 236.80, 183.67, and 162.31 mg/kg, resp.). The concentrations of the trace elements were within the recommended limits, indicating that the honeys were of good quality. Principal component analysis reveals good discrimination between the different honey samples. The pesticide analysis for the presence of organophosphorus and carbamates was performed by high performance liquid chromatography (HPLC). No pesticide residues were detected in any of the investigated honey samples, indicating that the honeys were pure. Our study reveals that Malaysian honeys are rich sources of minerals with trace elements present within permissible limits and that they are free from pesticide contamination.",
Arsenic,1344581,"Strategic selection of an optimal sorbent mixture for in-situ remediation of heavy metal contaminated sediments: Framework and case study Abstract: Aquatic sediments contaminated with heavy metals originating from mining and metallurgical activities pose significant risk to the environment and human health. These sediments not only act as a sink for heavy metals, but can also constitute a secondary source of heavy metal contamination. A variety of sorbent materials has demonstrated the potential to immobilize heavy metals. However, the complexity of multi-element contamination makes choosing the appropriate sorbent mixture and application dosage highly challenging. In this paper, a strategic framework is designed to systematically address the development of an in-situ sediment remediation solution through Assessment, Feasibility and Performance studies. The decision making tools and the experimental procedures needed to identify optimum sorbent mixtures are detailed. Particular emphasis is given to the utilization and combination of commercially available and waste-derived sorbents to enhance the sustainability of the solution. A specific case study for a contaminated sediment site in Northern Belgium with high levels of As, Cd, Pb and Zn originating from historical non-ferrous smelting is presented. The proposed framework is utilized to achieve the required remediation targets and to meet the imposed regulations on material application in natural environments.",
Arsenic,628334,"Sodium arsenite exposure alters cell migration, focal adhesion localization and decreases tyrosine phosphorylation of focal adhesion kinase in H9C2 myoblasts Abstract: Exposure to the environmental toxicant arsenic is reported to produce a variety of effects including disruption of signal transduction pathways, cell proliferation, and apoptosis. This suggests that arsenite may not have specific targets but rather extremely broad effects. The present study was designed to test the hypothesis that arsenite alters signaling involved in focal adhesion structure and function in cultured myoblasts. H9C2 cells were exposed to 1, 2.5, 5, or 10 microM sodium arsenite for 48 h. MTT metabolism and staining by neutral red, trypan blue, and propidium iodide showed that sodium arsenite treatments of 5 microM or less were not overtly cytotoxic. At these doses, sodium arsenite did not affect the amount of polymerized actin in cells, rate of protein synthesis, or amounts of vinculin, talin, paxillin, and focal adhesion kinase (FAK) in cells. However, sodium arsenite-treated cells contained fewer focal adhesions with an altered distribution pattern. Sodium arsenite exposure caused a dose-dependent reduction in cell migration and cell attachment rates. The average area of substrate covered by a cell was also reduced, although the average volume of cells was not significantly affected. Sodium arsenite exposure resulted in reduced tyrosine phosphorylation of FAK, its substrate paxillin and the FAK auto- phosphorylation site, Tyr397. Our results indicate that sodium arsenite can alter focal adhesion structure and function, thus affecting cell attachment and migration and possibly other aspects of focal adhesion function such as integrin signaling. These diverse consequences may be mediated by a relatively specific inhibition of FAK tyrosine phosphorylation, modifying scaffolding proteins.",
Arsenic,1034969,"Two examples of environmental problems occurring in remote sparsely populated areas Abstract: Studies in two widely separated remote areas are presented. Arsenic from gold mining contaminates the town of Yellowknife, North West Territories, Canada, An electromyographic study was carried out on 517 people in Yellowknife and a control population. Correlations between hair arsenic levels and nerve velocity, although not striking, are noted. Mercury contamination of fish in a pristine environment in Lake Murray, Western Province, Papua New Guinea, is reflected in elevated hair and urine levels in the local inhabitants. An attempt was made to determine the effects of mercury on the people and 40% of those tested had albumen in their urine. The conclusions drawn from these studies are given. The problems imposed on epidemiological studies by remote areas and harsh conditions are suggested.",
Arsenic,1327461,"Effect of proteasome inhibition on toxicity and CYP3A23 induction in cultured rat hepatocytes: comparison with arsenite Abstract: Previous work in our laboratory has shown that acute exposure of primary rat hepatocyte cultures to non-toxic concentrations of arsenite causes major decreases in the DEX-mediated induction of CYP3A23 protein, with minor decreases in CYP3A23 mRNA. To elucidate the mechanism for these effects of arsenite, the effects of arsenite and proteasome inhibition, separately and in combination, on induction of CYP3A23 protein were compared. The proteasome inhibitor, MG132, inhibited proteasome activity, but also decreased CYP3A23 mRNA and protein. Lactacystin, another proteasome inhibitor, decreased CYP3A23 protein without affecting CYP3A23 mRNA at a concentration that effectively inhibited proteasome activity. This result, suggesting that the action of lactacystin is similar to arsenite and was post-transcriptional, was confirmed by the finding that lactacystin decreased association of DEX-induced CYP3A23 mRNA with polyribosomes. Both MG132 and lactacystin inhibited total protein synthesis, but did not affect MTT reduction. Arsenite had no effect on ubiquitination of proteins, nor did arsenite significantly affect proteasomal activity. These results suggest that arsenite and lactacystin act by similar mechanisms to inhibit translation of CYP3A23.",
Arsenic,1026143,"Lymphokine-activated killer T-cell-originated protein kinase phosphorylation of histone H2AX prevents arsenite-induced apoptosis in RPMI7951 melanoma cells Abstract: <strong>PURPOSE: </strong>Arsenic is a valuable therapeutic tool in cancer treatment. Lymphokine-activated killer T-cell-originated protein kinase (TOPK) is highly expressed in cancer cells, but its specific function is still unknown. We investigated the role of TOPK in arsenic-induced apoptosis in RPMI7951 human melanoma cells.<br /><br /><strong>EXPERIMENTAL DESIGN: </strong>Expression of TOPK was evaluated in different melanoma cell lines, and liquid chromatography-tandem mass spectrometry analysis was used to identify proteins binding with TOPK. Immunofluorescence, Western blot, and flow cytometry were used to assess the effect of arsenic on TOPK, histone H2AX, and apoptosis in RPMI7951 cells.<br /><br /><strong>RESULTS: </strong>Melanoma cell lines expressing high levels of TOPK were more resistant to arsenite (As(3+))-induced apoptosis. As(3+) treatment induced phosphorylation of TOPK and histone H2AX in RPMI7951 human melanoma cells. Liquid chromatography-tandem mass spectrometry results indicated that TOPK could bind with histone H2AX, and in vitro and in vivo assays confirmed that TOPK binds with and phosphorylates histone H2AX. As(3+) treatment caused phosphorylation of TOPK, which colocalized with phosphorylated histone H2AX in the nucleus. TOPK small interfering RNA cells exhibited a decreased phosphorylation of histone H2AX with As(3+) treatment. As(3+)-induced apoptosis was decreased in H2AX(-/-) cells but increased in TOPK small interfering RNA cells.<br /><br /><strong>CONCLUSIONS: </strong>TOPK binds with histone H2AX and inhibits As(3+)-induced apoptosis through phosphorylation of histone H2AX. Melanoma cell lines with high levels of TOPK are more resistant to As(3+)-induced apoptosis. Therefore, inhibition of TOPK activity combined with As(3+) treatment may be helpful in the treatment of melanomas.",
Arsenic,2088361,Bronze technology of the ancient megalithic communities in the Vidarbha region of India Abstract: ,
Arsenic,628426,"Nucleolin links to arsenic-induced stabilization of GADD45alpha mRNA Abstract: The present study shows that arsenic induces GADD45alpha (growth arrest and DNA damage inducible gene 45alpha) mainly through post-transcriptional mechanism. Treatment of the human bronchial epithelial cell line, BEAS-2B, with arsenic(III) chloride (As3+) resulted in a significant increase in GADD45alpha protein and mRNA. However, As3+ only exhibited a marginal effect on the transcription of the GADD45alpha gene. The accumulation of GADD45alpha mRNA is largely achieved by the stabilization of GADD45alpha mRNA in the cellular response to As3+. As3+ is able to induce binding of mRNA stabilizing proteins, nucleolin and less potently, HuR, to the GADD45alpha mRNA. Although As3+ was unable to affect the expression of nucleolin, treatment of the cells with As3+ resulted in re-distribution of nucleolin from nucleoli to nucleoplasm. Silencing of the nucleolin mRNA by RNA interference reversed As3+-induced stabilization of the GADD45alpha mRNA and accumulation of the GADD45alpha protein. Stabilization of GADD45alpha mRNA, thus, represents a novel mechanism contributing to the production of GADD45alpha and cell cycle arrest in response to As3+.",
Arsenic,2347706,"Elevated arsenic and manganese in groundwaters of Murshidabad, West Bengal, India Abstract: High levels of geogenic arsenic (As) and manganese (Mn) in drinking water has led to widespread health problems for the population of West Bengal, India. Here we delineate the extent of occurrences of As and Mn in Murshidabad, where the contaminated aquifers occur at shallow depths between 35 and 40 m and where access to safe drinking water is a critical issue for the local population. A total of 78 well-water samples were taken in 4 blocks on either side of the river Bhagirathi: Nabagram and Kandi (west, Pleistocene sediments), Hariharpara and Beldanga (east, Holocene sediments). High As, total iron (FeT) and low Mn concentrations were found in waters from the Holocene gray sediment aquifers east of the river Bhagirathi, while the opposite was found in the Pleistocene reddish-brown aquifer west of the river Bhagirathi in Murshidabad. Speciation of As in water samples from Holocene sediments revealed the dominant species to be As(III), with ratios of As(III):AsT ranging from 0.55 to 0.98 (average 0.74). There were indications from saturation index estimations that Mn solubility is limited by the precipitation of MnCO3. Tubewells from high As areas in proximity to anthropogenic waste influx sources showing high molar Cl/Br ratios, low SO4(2-) and low NO3(-) demonstrate relatively lower As concentrations, thereby reducing As pollution in those wells. Analyses of core samples (2 in each of the blocks) drilled to a depth of 45 m indicate that there is no significant variation in bulk As (5-20mg/kg) between the Holocene and Pleistocene sediments, indicating that favorable subsurface redox conditions conducive to mobilization are responsible for the release of As. The same applies to Mn, but concentrations vary more widely (20-2000 mg/kg). Sequential extraction of Holocene sediments showed As to be associated with 'specifically sorbed-phosphate-extractable' phases (10-15%) and with 'amorphous and well crystalline Fe-oxyhydroxide' phases (around 37%) at As-contaminated well depths, suggesting that the main As release mechanisms could be either competitive ion exchange with PO4(3-), or the dissolution of Fe oxyhydroxides. In the Pleistocene sediments Mn is predominantly found in the easily exchangeable fraction.",
Arsenic,1508562,"Arsenic removal by solar-driven membrane distillation: modeling and experimental investigation with a new flash vaporization module Abstract: A modeling and simulation study was carried out on a new flux-enhancing and solar-driven membrane distillation module for removal of arsenic from contaminated groundwater. The developed new model was validated with rigorous experimental investigations using arsenic-contaminated groundwater. By incorporating flash vaporization dynamics, the model turned out to be substantially different from the existing direct contact membrane distillation models and could successfully predict (with relative error of only 0.042 and a Willmott d-index of 0.997) the performance of such an arsenic removal unit where the existing models exhibited wide variation with experimental findings in the new design. The module with greater than 99% arsenic removal efficiency and greater than 50 L/m2 x h flux could be implemented in arsenic-affected villages in Southeast Asian countries with abundant solar energy, and thus could give relief to millions of affected people. These encouraging results will raise scale-up confidence.",
Arsenic,1021532,"Direct analysis and stability of methylated trivalent arsenic metabolites in cells and tissues Abstract: Chronic ingestion of water containing inorganic arsenic (iAs) has been linked to a variety of adverse health effects, including cancer, hypertension and diabetes. Current evidence suggests that the toxic methylated trivalent metabolites of iAs, methylarsonous acid (MAs(III)) and dimethylarsinous acid (DMAs(III)) play a key role in the etiology of these diseases. Both MAs(III) and DMAs(III) have been detected in urine of subjects exposed to iAs. However, the rapid oxidation of DMAs(III) and, to a lesser extent, MAs(III) in oxygen-rich environments leads to difficulties in the analysis of these metabolites in samples of urine collected in population studies. Results of our previous work indicate that MAs(III) and DMAs(III) are relatively stable in a reducing cellular environment and can be quantified in cells and tissues. In the present study, we used the oxidation state-specific hydride generation-cryotrapping-atomic absorption spectroscopy (HG-CT-AAS) to examine the presence and stability of these trivalent metabolites in the liver of mice and in UROtsa/F35 cells exposed to iAs. Tri- and pentavalent metabolites of iAs were analyzed directly (without chemical extraction or digestion). Liver homogenates prepared in cold deionized water and cell culture medium and lysates were stored at either 0 °C or -80 °C for up to 22 days. Both MAs(III) and DMAs(III) were stable in homogenates stored at -80 °C. In contrast, DMAs(III) in homogenates stored at 0 °C began to oxidize to its pentavalent counterpart after 1 day; MAs(III) remained stable for at least 3 weeks under these conditions. MAs(III) and DMAs(III) generated in UROtsa/F35 cultures were stable for 3 weeks when culture media and cell lysates were stored at -80 °C. These results suggest that samples of cells and tissues represent suitable material for the quantitative, oxidation state-specific analysis of As in laboratory and population studies examining the metabolism or toxic effects of this metalloid.",
Arsenic,1290265,"Vitamin E-supplementation protect chromium (VI)-induced spermatogenic and steroidogenic disorders in testicular tissues of rats Abstract: Excess chromium (Cr) exposure is associated with various pathological conditions including reproductive dysfunction. Generation of oxidative stress is one of the plausible mechanisms behind Cr induced cellular deteriorations. The efficacy of vitamin E to combat Cr induced oxidative damage in adult rat testis has investigated in the current study. Adult male rats exposed to hexavalent Cr (intraperitoneal injection with 0.4 mg K(2)Cr(2)O(7)/ kg bw/day) for 26 days resulted in decreased accessory sex organs weight compared to controls. Development of oxidative stress in testis was evidenced by increased lipid peroxidation along with decreased superoxide dismutase (SOD) and catalase activities than control animals. Marked reduction in the activities of testicular steroidogenic enzymes; Delta(5)3beta-hydroxysteroid dehydrogenase (HSD), 17beta-HSD, serum testosterone and Leutinizing Hormone (LH) levels were observed. However significant increase in serum Follicle Stimulating Hormone (FSH) level was observed with Cr treated group. Histological evaluation of testis revealed degeneration of stage VII spermatogenic cycle along with decrease in epithelial cell height in epididymis and seminiferous tubules; number of different germ cells per seminiferous tubule and seminiferous tubular diameter reduced after Cr exposure. Simultaneous oral supplementation of vitamin E (50mg/kg bw/day) in Cr exposed rats showed less oxidative damage and restored the otherwise altered testicular activities. Epididymal sperm number was also restored in vitamin E-supplemented group than Cr induced rats. This study implicates vitamin E as a possible protective agent against Cr induced spermatogenic and steroidogenic alteration.",
Arsenic,1021495,"Hepatoprotective role of vitamin B(12) and folic acid in arsenic intoxicated rats Abstract: The present study elucidated the protective role of vitamin B(12) with folic acid against arsenic-induced hepatotoxicity in female rats. Ingestion of sodium-arsenite- contaminated water [0.4?ppm/100?g body weight (b.w.)/day] in combination with vitamin B(12) plus folic acid (0.07 and 4.0 ?g, respectively/100?g b.w./day) for 24 days to Wistar rats offered a significant protection against alone arsenic-induced distorted liver function, damaged histoarchitecture, elevated oxidative stress, and DNA fragmentation of hepatic tissues. Arsenic only exposure decreased hepatic superoxide dismutase (SOD), catalase activities, and the level of nonprotein-soluble thiol (NPSH), with a concomitant increase in thiobarbituric acid reactive substances (TBARS) and conjugated dienes (CDs) in the liver. Vitamin supplementation restrained the increase of TBARS and CDs by restoring catalase, SOD, and NPSH levels. Restricted generation of free radicals may be correlated to the protection of DNA stability and hepatic morphology. This study explains the decisive role of vitamin B(12) with folic acid to ameliorate arsenic-mediated liver injuries.",
Arsenic,1797801,"Desorption electrospray ionization mass spectrometry (DESI-MS) applied to the speciation of arsenic compounds from fern leaves Abstract: The different chemical forms of arsenic compounds, including inorganic and organic species, present distinct environmental impacts and toxicities. Desorption electrospray ionization mass spectrometry (DESI-MS) is an excellent technique for in situ analysis, as it operates under atmospheric pressure and room temperature and is conducted with no/minimal sample pretreatment. Aimed at expanding its scope, DESI-MS is applied herein for the quick and reliable detection of inorganic (arsenate-As(V): AsO4 (3-) and arsenite-As(III): AsO2 (-)) and organic (dimethylarsinic acid-DMA: (CH3)2AsO(OH) and disodium methyl arsonate hexahydrate: CH3AsO3·2Na·6H2O) arsenic compounds in fern leaves. Operational conditions of DESI-MS were optimized with DMA standard deposited on paper surfaces to improve ionization efficiency and detection limits. Mass spectra data for all arsenic species were acquired in both the positive and negative ion modes. The positive ion mode was shown to be useful in detecting both the organic and inorganic arsenic compounds. The negative ion mode was shown only to be useful in detecting As(V) species. Moreover, MS/MS spectra were recorded to confirm the identity of each arsenic compound by the characteristic fragmentation profiles. Optimized conditions of DESI-MS were applied to the analysis of fern leaves. LC-ICP-MS was employed to confirm the results obtained by DESI-MS and to quantify the arsenic species in fern leaves. The results confirmed the applicability of DESI-MS in detecting arsenic compounds in complex matrices.",
Arsenic,2088550,"Genome-wide analysis of DNA methylation changes induced by gestational arsenic exposure in liver tumors Abstract: Inorganic arsenic is known to be a human carcinogen. Since previous studies have reported that DNA methylation changes are involved in arsenic-induced carcinogenesis, DNA methylation changes that are specific to arsenic-induced tumors would be useful to distinguish tumors induced by arsenic from tumors caused by other factors and to dissect arsenic carcinogenesis. Previous studies have shown that gestational arsenic exposure of C3H mice, which tend to spontaneously develop liver tumors, increases the incident of tumors in male offspring. In this study we used the same experimental protocol as in those previous studies and searched for DNA regions where methylation status was specifically altered in the liver tumors of arsenic-exposed offspring by using methylated DNA immunoprecipitation-CpG island microarrays. The methylation levels of the DNA regions selected were measured by quantitative methylation-specific PCR and bisulfite sequencing. The results of this study clarified a number of regions where DNA methylation status was altered in the liver tumors in the C3H mice compared to the normal liver tissues. Among such regions, we demonstarted that a gene body region of the oncogene Fosb underwent alteration in DNA methylation by gestational arsenic exposure. We also showed that Fosb expression significantly increased corresponding to the DNA methylation level of the gene body in the arsenic-exposed group. These findings suggest that the DNA methylation status can be utilized to identify tumors increased by gestational arsenic exposure. This article is protected by copyright. All rights reserved.",
Arsenic,1015999,"Arsenic mass balance in a paper mill and impact of the arsenic release from the WWTP effluent on the Moselle River Abstract: Rivers used for drinking water production might be subject to anthropogenic pollution discharge upstream of the intake point. This problem was investigated in the case of the Moselle River, used for water production in Nancy (350,000 inhabitants) and which might be impacted by industrial activities 60 km upstream. The arsenic flux of a pulp and paper mill discharging in the Moselle River at this location has been more specifically investigated. The main sources of arsenic in that mill seemed to be the recovered papers and the gravel pit water used as feed water. The arsenic input related to wood and bark was limited. The main arsenic outputs from the plant were the paper produced on site and the deinking sludge. The arsenic concentration in the effluent of the wastewater treatment plant (WWTP) was not correlated to the one in the gravel pit water, but may depend on the operating conditions of the WWTP or the changes in processes of the mill. The impact of this anthropogenic source of arsenic on the Moselle River was slightly larger in summer, when the flowrate was lower. Globally the impact of the paper mill on the Moselle River water quality was limited in terms of arsenic.",
Arsenic,1250983,"Do arbuscular mycorrhizal fungi affect arsenic accumulation and speciation in rice with different radial oxygen loss? Abstract: The effects of arbuscular mycorrhizal fungi (AMF) on the temporal variation of arsenic (As) speciation and accumulation in two paddy rice cultivars (TD 71 and Xiushui 11) with different degrees of radial oxygen loss (ROL) at three growth periods (day 7, day 35, day 63 after flooding the soil) were investigated in soil, spiked with and without 30mgAskg(-1). The results showed that TD 71 with high ROL colonized by Glomus intraradices led to higher root colonization rates than Xiushui 11 at three growth periods, both in soil with or without 30mgAskg(-1) (p&lt;0.05). Mycorrhizal inoculation led to elevated (p&lt;0.05) root ratios of arsenite (As(III)) conc./arsenate (As(V)) conc. (concentration) in TD 71 with high ROL at three growth periods in As contaminated flooding soils. Furthermore, the ratios of As(III) conc./As(V) conc. in roots of TD71 were significantly more than Xiushui 11 when colonized by AMF at three growth periods in 30mgAskg(-1) soil (p&lt;0.05). Therefore, rice with high ROL can favor AM fungal infection and enhance root ratio of As(III) conc./As(V) conc. in the presence of AMF.",
Arsenic,1031521,"Moderate perinatal arsenic exposure alters neuroendocrine markers associated with depression and increases depressive-like behaviors in adult mouse offspring Abstract: Arsenic is one of the most common heavy metal contaminants found in the environment, particularly in water. We examined the impact of perinatal exposure to relatively low levels of arsenic (50 parts per billion, ppb) on neuroendocrine markers associated with depression and depressive-like behaviors in affected adult C57BL/6J mouse offspring. Whereas most biomedical research on arsenic has focused on its carcinogenic potential, a few studies suggest that arsenic can adversely affect brain development and neural function. Compared to controls, offspring exposed to 50 parts per billion arsenic during the perinatal period had significantly elevated serum corticosterone levels, reduced whole hippocampal CRFR 1 protein level and elevated dorsal hippocampal serotonin 5HT 1A receptor binding and receptor-effector coupling. 5HT 1A receptor binding and receptor-effector coupling were not different in the ventral hippocampal formation, entorhinal or parietal cortices, or inferior colliculus. Perinatal arsenic exposure also significantly increased learned helplessness and measures of immobility in a forced swim task. Taken together, these results suggest that perinatal arsenic exposure may disrupt the regulatory interactions between the hypothalamic-pituitary-adrenal axis and the serotonergic system in the dorsal hippocampal formation in a manner that predisposes affected offspring to depressive-like behavior. These results are the first to demonstrate that relatively low levels of arsenic exposure during development can have long-lasting adverse effects on behavior and neurobiological markers associated with these behavioral changes.",
Arsenic,1519197,"Effect of quick lime and superphosphate additives on emergence and survival of Rumex obtusifolius seedlings in acid and alkaline soils contaminated by As, Cd, Pb, and Zn Abstract: ",
Arsenic,1019415,"Sodium arsenate induces overproduction of interleukin-1alpha in murine keratinocytes: role of mitochondria Abstract: It has recently been demonstrated that arsenic induces overexpression of keratinocyte-derived growth factors, which are likely to have a significant role in arsenic-induced skin hyperkeratoses and cancer. The mechanism(s) involved in this induction are, however, still elusive. The purpose of this study was to investigate the early intracellular events that follow in vitro treatment with sodium arsenate in a murine keratinocyte cell line (HEL30), which leads to cytokine overproduction. First, we observed that sodium arsenate induced a concentration-dependent production of interleukin-1alpha and a significant increase in cell proliferation, that could be suppressed by the addition of a neutralizing antibody against murine interleukin-1alpha, confirming the ability of arsenic to induce keratinocyte growth-promoting cytokines. Electron microscopic analysis revealed that arsenate induced a dramatic alteration in keratinocyte mitochondria. This effect could be prevented by rotenone pretreatment, which suggests the possible involvement of mitochondria-derived reactive oxygen species. Arsenic induced a concentration- and time-dependent increase in cellular oxidative activity, which was followed by activation of redox-sensitive transcription factors such as nuclear factor-kappaB and activator protein-1, that are essential for interleukin-1alpha synthesis. Prior treatment with rotenone or prolonged treatment with ethidium bromide, an inhibitor of mitochondrial DNA and RNA synthesis, to deplete cells of functional mitochondria, completely prevented sodium arsenate-induced interleukin-1alpha production, this indicates the pivotal role of these organelles in sodium arsenate-induced keratinocyte growth factors.",
Arsenic,1026001,"Sampling methods to determine the spatial gradients and flux of arsenic at a groundwater seepage zone Abstract: Sampling techniques with centimeter-scale spatial resolution were applied to investigate biogeochemical processes controlling groundwater arsenic fate across the groundwater-surface water interface at a site characterized by fine sediments (40% sand, 46% silt, 14% clay). Freeze-core sediment collection gave more detailed and depth-accurate arsenic and iron contaminant and microbial distributions than could be obtained with the use of a hand auger. Selective chemical extractions indicated that greater than 90% of the arsenic was strongly sorbed to very amorphous iron oxyhydroxides. These solids accounted for more than 80% of the total iron in the sediments. Microbial enrichments indicated that iron-oxidizing bacteria (IOB) were up to 1% of the total bacterial abundance, whereas iron-reducing bacteria (IRB) were about two orders of magnitude less abundant than IOB. The abundance of IRB mirrored the IOB depth profile. Push-point pore-water sampling captured large amounts of sediment fines, even with controlled (20 ml/min) water withdrawal, thereby necessitating filtration before water quality analysis. Bead columns containing glass media enabled short-term (29 d) characterization of pore water-to-sediment transfer of arsenic and iron. Bead columns indicated quantitative capture of groundwater arsenic and iron during 2003, suggesting that freeze-core inventories corresponded to 2 to 20 years of accumulation, depending on location.",
Arsenic,8337,"Environmental variation of arsenic levels in human blood determined by neutron activation analysis Abstract: Arsenic levels in blood plasma and red cells from patients with Blackfoot disease, a peripheral arteriosclerosis endemic to a small area in Taiwan, were studied in relation to healthy individuals from the same and other parts of Taiwan and compared with arsenic levels in a control group from Denmark. Arsenic was determined by neutron activation analysis with radiochemical separation and re-irradiation yield determination. The precision and accuracy of the results have been carefully evaluated in order to permit quantitative tests for the significance of the observed differences. The results from Taiwan followed a logarithmic normal distribution, and no difference was found between Blackfoot patients and their healthy family members. However, their overall arsenic levels were higher than the Taiwan average, presumably because of arsenic in their drinking water. Much lower levels were found in Denmark, which geochemically belongs to a soil zone with less arsenic than Taiwan.",
Arsenic,627091,"Bronchiectasis in persons with skin lesions resulting from arsenic in drinking water Abstract: Background: Arsenic is a unique human carcinogen in that it causes lung cancer by exposure through ingestion (in drinking water) as well as through inhalation. Less is known about nonmalignant pulmonary disease after exposure to arsenic in drinking water. Methods: We recruited 108 subjects with arsenic-caused skin lesions and 150 subjects without lesions from a population survey of over 7000 people in an arsenic-exposed region in West Bengal, India. Thirty-eight study participants who reported at least 2 years of chronic cough underwent high-resolution computed tomography (CT); these scans were read by investigators in India and the United States without knowledge of the presence or absence of skin lesions. Results: The mean (± standard deviation) bronchiectasis severity score was 3.4 (± 3.6) in the 27 participants with skin lesions and 0.9 (± 1.6) in the 11 participants without these lesions. In subjects who reported chronic cough, CT evidence of bronchiectasis was found in 18 (67%) participants with skin lesions and 3 (27%) subjects without skin lesions. Overall, subjects with arsenic-caused skin lesions had a 10-fold increased prevalence of bronchiectasis compared with subjects who did not have skin lesions (adjusted odds ratio = 10; 95% confidence interval = 2.7-37). Conclusions: These results suggest that, in addition to being a cause of lung cancer, ingestion of high concentrations of arsenic in drinking water may be a cause of bronchiectasis.",
Arsenic,1019591,"Effect of glutathione depletion and metallothionein gene expression on arsenic-induced cytotoxicity and c-myc expression in vitro Abstract: Arsenic exposure is clearly linked to human cancer. In rodent cells, arsenic has been reported to induce aberrant gene expression, including activation of the proto-oncogene c-myc. Abnormal or altered expression of such oncogenes can be involved in the acquisition of a malignant phenotype. Although its mechanism of action is unclear, arsenic is known to exert at least some of its toxic effects through interaction with sulfhydryl groups, and the non-protein sulfhydryl glutathione (GSH) appears to play an important role in detoxication of arsenic. Similarly, metallothionein (MT), a metal-binding protein with high sulfhydryl content, often functions in defense against metal-induced or oxidative cellular injury. Therefore, we examined the relationship among GSH, MT gene expression, and arsenic-induced toxicity or c-myc expression in cultured rat myoblast (L6) cells. In initial toxicity studies, arsenic was used in both the trivalent (arsenite) and pentavalent (arsenate) forms. The role of GSH was studied by pretreating cells with L-buthionine sulfoximine (BSO), which induces a marked depletion of GSH. In vitro exposure of L6 cells to BSO (1 to 25 microM) resulted in dose-dependent decreases in GSH. GSH depletion sensitized cells to both arsenite and arsenate. Zinc pretreatment, at levels which highly activated MT expression, had no effect on arsenite-induced cytotoxicity. Arsenite (1 microM) alone modestly increased c-myc expression from 1 to 4 h after treatment (maximum of 2.0-fold over control). After GSH depletion cells responded to arsenite exposure with much larger increases in c-myc transcription (3.2-fold over control). Zinc pretreatment had no reductive effect on arsenite-induced c-myc expression despite markedly activating the MT gene. Thus, it appears that the cellular levels of GSH, but not MT gene expression, play an important role in resistance to arsenic toxicity and aberrant gene activation. Moreover, depletion of GSH enhances arsenic-induced proto-oncogene activation, which might contribute to subsequent transformation.",
Arsenic,1024493,"Supplementation of ascorbic acid and alpha-tocopherol prevents arsenic-induced protein oxidation and DNA damage induced by arsenic in rats Abstract: Contamination of arsenic in drinking water is associated with several human diseases including cancer. It has been reported that oxidative stress plays a vital role in arsenic-induced biochemical and molecular alterations. The aim of the present study was to improve the understanding of arsenic-induced oxidative damage to proteins and to DNA and the role of antioxidants such as ascorbic acid and alpha-tocopherol in alleviating arsenic-induced damages in experimental rats. A significant increase in the levels of protein oxidation, DNA strand breaks, and DNA-protein cross-links was observed in blood, liver, and kidney of rats exposed to arsenic (100 ppm in drinking water) for 30 days. Co-administration of ascorbic acid and alpha-tocopherol to arsenic-exposed rats showed a substantial reduction in the levels of arsenic-induced oxidative products of protein and DNA. The results of this study support that free radical-mediated toxic manifestations of arsenic and also suggest that ascorbic acid and alpha-tocopherol supplementation can improve the arsenic-induced molecular alterations.",
Arsenic,1252765,"Arsenite and its mono- and dimethylated trivalent metabolites enhance the formation of benzo[a]pyrene diol epoxide-DNA adducts in Xeroderma pigmentosum complementation group A cells Abstract: Recently, inorganic arsenite (iAs(III)) and its mono- and dimethylated metabolites have been examined for their interference with the formation and repair of benzo[a]pyrene diol epoxide (BPDE)-induced DNA adducts in human cells (Schwerdtle, ., Walter, I., and Hartwig, A. (2003) DNA Repair 2, 1449 - 1463). iAs(III) and monomethylarsonous acid (MMA(III)) were found to be able to enhance the formation of BPDE-DNA adducts, whereas dimethylarsinous acid (DMA(III)) had no enhancing effect at all. The anomaly manifested by DMA(III) prompted us to further investigate the effects of the three trivalent arsenic species on the formation of BPDE-DNA adducts. Use of a nucleotide excision repair (NER)-deficient Xeroderma pigmentosum complementation group A cell line (GM04312C) allowed us to dissect DNA damage induction from DNA repair and to examine the effects of arsenic on the formation of BPDE-DNA adducts only. At concentrations comparable to those used in the study by Schwerdtle et al., we found that each of the three trivalent arsenic species was able to enhance the formation of BPDE-DNA adducts with the potency in a descending order of MMA(III) &gt; DMA(III) &gt; iAs(III), which correlates well with their cytotoxicities. Similar to iAs(III), DMA(III) modulation of reduced glutathione (GSH) or total glutathione S-transferase (GST) activity could not account for its enhancing effect on DNA adduct formation. Additionally, the enhancing effects elicited by the trivalent arsenic species were demonstrated to be highly time-dependent. Thus, although our study made use of short-term assays with relatively high doses, our data may have meaningful implications for carcinogenesis induced by chronic exposure to arsenic at low doses encountered environmentally.",
Arsenic,1020870,Successful treatment of multiple premalignant and malignant lesions in arsenical keratosis with a combination of acitretin and intralesional 5-fluorouracil Abstract: A case of arsenical keratosis with multiple lesions of Bowen's disease and squamous cell carcinoma is described. The patient was successfully treated with a combination of acitretin and intralesional 5-fluorouracil. All the lesions resolved after three months of therapy with no side effects and no recurrence during four months of follow-up.,
Arsenic,2064138,Identifying N-6 Adenine-Specific DNA Methyltransferase 1 (N6AMT1) Polymorphisms Associated with Arsenic Methylation Status Using a Custom and Low-Cost Genotyping Method Abstract: ,
Arsenic,1019609,"Expression of bcl-2, p53 and Ki-67 in arsenical skin cancers Abstract: To investigate the regulation of apoptosis and proliferation in arsenic-induced skin cancers, we examined the expression of bcl-2, p53, and Ki-67 using immunohistochemical staining. Thirty patients with Bowen's disease (BD), ten with basal cell carcinoma (BCC), eight with squamous cell carcinoma (SCC) and eleven of perilesional normal skin (PLN) of the non-sun exposure sites from endemic area were examined. The results showed that: 1) bcl-2 was expressed in all of the BCC homogeneously, in none of the SCC, and in 12/30 of the BD focally or homogeneously; 2) p53 was expressed in all of the arsenical skin cancers with a labelling index of 75 +/- 14% of BD, 50 +/- 17% of BCC, 61 +/- 15% of SCC, and also in all of the perilesional normal skin with a labelling index of 55 +/- 24%; 3) Ki-67 was expressed in all of the skin cancers with labelling index of 58 +/- 17% of BD, 12 +/- 7% of BCC, 47 +/- 21% of SCC, and in 9/11 of PLN with a labelling index of 41 +/- 24%. Expression of bcl-2 in BCC or BD is related to the phenotype of germinative basal cell. The constant expression of bcl-2 i early dysplastic cells of BD and the earliest expression of P53 in the basal cells of perilesional normal skin indicate that the initial step of arsenic-induced carcinogenesis is from the basal germinative cells. There is no mutual relationship between bcl-2, p53 or Ki-67 expression in any type of the arsenical skin cancers, but there is a positive correlation between p53 and Ki-67 expression identified in perilesional normal skin. BD had the highest labelling index of p53 and Ki-67.",
Arsenic,1252651,"Gastric cancer in New Mexico counties with significant deposits of uranium Abstract: Several counties in northern New Mexico display high rates of mortality from gastric cancer. Significant differences in sex-specific, age-adjusted, average annual stomach cancer mortality rates among whites from 1970-1979 were found between counties with significant deposits of uranium compared to those without significant deposits. These results remained unchanged when either socioeconomic status or Hispanic ethnicity were considered. Additional research needs to consider individual characteristics and competing risk factors for individuals with gastric cancer in these counties. A working hypothesis is that residents of counties with significant deposits of uranium are exposed to higher-than-average environmental levels of radionuclides such as radon and radon daughters, or to trace elements such as arsenic, cadmium, selenium, and lead which are commonly found in areas with uranium deposits.",
Arsenic,479041,"Chronic UVA irradiation of human HaCaT keratinocytes induces malignant transformation associated with acquired apoptotic resistance Abstract: Ultraviolet A ( UVA, 315 - 400 nm), constituting about 95% of ultraviolet irradiation in natural sunlight, represents a major environmental challenge to the skin and is clearly associated with human skin cancer. It has proven difficult to show direct actions of UVA as a carcinogen in human cells. Here, we demonstrate that chronic UVA exposures at environmentally relevant doses in vitro can induce malignant transformation of human keratinocytes associated with acquired apoptotic resistance. As evidence of carcinogenic transformation, UVA-long-treated ( 24 J/cm(2) once/week for 18 weeks) HaCaT ( ULTH) cells showed increased secretion of matrix metalloproteinase ( MMP-9), overexpression of keratin 13, altered morphology and anchorage-independent growth. Malignant transformation was established by the production of aggressive squamous cell carcinomas after inoculation of ULTH cells into nude mice ( NCr-nu). ULTH cells were resistant to apoptosis induced not only by UVA but also by UVB and arsenite, two other human skin carcinogens. ULTH cells also became resistant to apoptosis induced by etoposide, staurosporine and doxorubicin hydrochloride. Elevated phosphorylation of protein kinase B ( PKB, also called AKT) and reduced expression of phosphatase and tensin homologue deleted on chromosome 10 ( PTEN) were detected in ULTH cells. The resistance of ULTH cells to UVA-induced apoptosis was reversed by either inhibition of phosphatidylinositol 3-kinase ( PI-3K) or adenovirus expression of PTEN or dominant negative AKT. These data indicate that UVA has carcinogenic potential in human keratinocytes and that the increased AKT signaling and decreased PTEN expression may contribute to this malignant transformation. Further comparisons between the transformed ULTH and control cells should lead to a better understanding of the mechanism of UVA carcinogenesis and may help identify biomarkers for UVA-induced skin malignancies.",
Arsenic,1346808,"Co(II) adsorption in aqueous media by a synthetic Fe-Mn binary oxide adsorbent Abstract: Co(II) adsorption on high-purity amorphous Fe–Mn binary oxide adsorbent was investigated. The Co(II) adsorption behavior of this synthetic material was studied and discussed as a function of contact time, pH and initial concentration. The Langmuir and Freundlich isotherm models were applied to fit the Co(II) adsorption data on Fe–Mn binary oxide with mesoporous particles of irregular surface morphology and a specific surface area of 201.8 m2 g?1 with a maximum capacity of 32.25 mg g?1. Various kinetic models applied to the adsorption rate data of the Co(II) ion were evaluated. The results show that the pseudo-second order and the intra-particle mass transfer diffusion models correlated best with the experimental rate data. The adsorption activation energy was found to be 9.07 kJ mol?1 indicating that it corresponds to a physical adsorption. The evaluated thermodynamics parameters of the adsorption values indicated the endothermic and spontaneous nature of the adsorption. The results obtained confirmed that Fe–Mn binary oxide had the potential to be utilized as a low-cost and relatively effective adsorbent for Co(II) removal from wastewater.",
Arsenic,1030406,"The DNA-binding activity of the human heat shock transcription factor is regulated in vivo by hsp70 Abstract: The human heat shock transcription factor (HSF) is maintained in an inactive non-DNA-binding form under nonstress conditions and acquires the ability to bind specifically to the heat shock promoter element in response to elevated temperatures or other conditions that disrupt protein structure. Here we show that constitutive overexpression of the major inducible heat shock protein, hsp70, in transfected human cells reduces the extent of HSF activation after a heat stress. HSF activation was inhibited more strongly in clones that express higher levels of hsp70. These results demonstrate that HSF activity is negatively regulated in vivo by hsp70 and suggest that the cell might sense elevated temperature as a decreased availability of hsp70. HSF activation in response to treatment with sodium arsenite or the proline analog azetidine was also depressed in hsp70-expressing cells relative to that in the nontransfected control cells. As well, the level of activated HSF decreased more rapidly in the hsp70-expressing clones when the cells were heat shocked and returned to 37 degrees C. These results suggest that hsp70 could play an active role in the conversion of HSF back to a conformation that does not bind the heat shock promoter element during the attenuation of the heat shock response.",
Arsenic,710873,"Association of genetic variation in cystathionine-beta-synthase and arsenic metabolism Abstract: Variation in individual susceptibility to arsenic-induced disease may be partially explained by genetic differences in arsenic metabolism. Mounting epidemiological evidence and in vitro studies suggest that methylated arsenic metabolites, particularly monomethylarsonic (MMA3), are more acutely toxic than inorganic arsenic; thus, MMA3 may be the primary toxic arsenic species. To test the role of genetic variation in arsenic metabolism, polymorphisms in genes involved in one-carbon metabolism [methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), cystathionine-beta-synthase (CBS), thymidylate synthase (TYMS), dihydrofolate reductase (DHFR), serine hydroxymethyltransferase 1 (SHMT1)] and glutathione biosynthesis [glutathione-S-transferase omega 1 (GSTO1)] were examined in an arsenic-exposed population to determine their influence in urinary arsenic metabolite patterns. In 142 subjects in Cordoba Province, Argentina, variant genotypes for CBS rs234709 and rs4920037 SNPs compared with wild-type homozygotes were associated with 24% and 26% increases, respectively, in the mean proportion of arsenic excreted as monomethylarsonic acid (%MMA). This difference is within the range of differences in %MMA seen between people with arsenic-related disease and those without such disease in other studies. Small inverse associations with CBS rs234709 and rs4920037 variants were also found for the mean levels of the proportion of arsenic excreted as dimethylarsinous acid (%DMA). No other genetic associations were found. These findings are the first to suggest that CBS polymorphisms may influence arsenic metabolism in humans and susceptibility to arsenic-related disease.",
Arsenic,1337513,"Therapeutic Roles of Curcumin: Lessons Learned from Clinical Trials Abstract: Extensive research over the past half century has shown that curcumin (diferuloylmethane), a component of the golden spice turmeric (Curcuma longa), can modulate multiple cell signaling pathways. Extensive clinical trials over the past quarter century have addressed the pharmacokinetics, safety, and efficacy of this nutraceutical against numerous diseases in humans. Some promising effects have been observed in patients with various pro-inflammatory diseases including cancer, cardiovascular disease, arthritis, uveitis, ulcerative proctitis, Crohn's disease, ulcerative colitis, irritable bowel disease, tropical pancreatitis, peptic ulcer, gastric ulcer, idiopathic orbital inflammatory pseudotumor, oral lichen planus, gastric inflammation, vitiligo, psoriasis, acute coronary syndrome, atherosclerosis, diabetes, diabetic nephropathy, diabetic microangiopathy, lupus nephritis, renal conditions, acquired immunodeficiency syndrome, ?-thalassemia, biliary dyskinesia, Dejerine-Sottas disease, cholecystitis, and chronic bacterial prostatitis. Curcumin has also shown protection against hepatic conditions, chronic arsenic exposure, and alcohol intoxication. Dose-escalating studies have indicated the safety of curcumin at doses as high as 12 g/day over 3 months. Curcumin's pleiotropic activities emanate from its ability to modulate numerous signaling molecules such as pro-inflammatory cytokines, apoptotic proteins, NF-?B, cyclooxygenase-2, 5-LOX, STAT3, C-reactive protein, prostaglandin E(2), prostate-specific antigen, adhesion molecules, phosphorylase kinase, transforming growth factor-?, triglyceride, ET-1, creatinine, HO-1, AST, and ALT in human participants. In clinical trials, curcumin has been used either alone or in combination with other agents. Various formulations of curcumin, including nanoparticles, liposomal encapsulation, emulsions, capsules, tablets, and powder, have been examined. In this review, we discuss in detail the various human diseases in which the effect of curcumin has been investigated.",
Arsenic,1025421,"Evaluation of micronucleus frequencies in blood lymphocytes from smelting plant workers exposed to arsenic Abstract: Arsenic is a world health problem due to the seriousness of its effects, mainly related with the increase of cancer. In Chile, the geological characteristics of the northern region, associated with the development of the copper mining and smelting activities, have contributed to increase the environmental levels of arsenic. This study has been conducted to investigate the relationship between arsenic occupational exposure and genotoxic effects in smelting plant workers. To determine the genotoxic risk related to the increase of cancer among the chronically exposed population, the frequency of micronuclei in blood (BNMN) has been evaluated. The study was carried out in a total of 207 men, divided into three groups: an exposed group of 105 individuals working in a smelting plant, an internal reference group with 52 employees at the same mine but in the administrative area, and an external reference group of 50 workers from another copper mine where no significant levels of arsenic were detected. As expected, differences between arsenic levels in urine have been detected between groups, with the exposed group being the one with a higher level of total arsenic in urine, followed by the internal reference group. Despite that, no significant differences in micronuclei frequencies in lymphocytes were detected among these groups.",
Arsenic,56253,"Mortality by cancer in groups of the Belgian population with a moderately increased intake of arsenic Abstract: OBJECT: The dose-response relationship for lung carcinoma and other cancers at low doses of As is highly uncertain because it is based on modeling data collected in populations with a high daily intake of the element. The finding of a slightly increased exposure to arsenic in certain groups of the Belgian general population prompted us to examine whether this had repercussions on the causes of mortality. METHOD: Statistics of mortality by causes with a possible link to exposure to the element (standardized mortality ratio) were analyzed in groups of the Belgian population previously shown to have been exposed to As from natural (drinking water) and/or industrial (nonferrous metal smelter emissions) sources. RESULTS: A moderately increased absorption of As, leading to a 3- to 4- fold higher urinary excretion (35 micrograms/day as compared with 6-10 micrograms As/day in nonexposed subjects) did not enhance the mortality by diseases of the nervous system, liver and heart, and cancers. An increase in mortality by lung cancer, however, was observed in men but not women living around zinc smelters and might be related to past occupational exposure and/or smoking habits. CONCLUSION: A low to moderate level of environmental exposure to inorganic arsenic (0.3 microgram As/m3 of air; 20-50 micrograms As/l of drinking water) does not seem to affect the causes of mortality, suggesting in particular nonlinearity of the dose-response relationship for arsenic and cancer.",
Arsenic,1348157,"Chronic arsenic toxicity: Clinical features, epidemiology, and treatment: Experience in Indo-Nepal border Abstract: Background: Chronic arsenic toxicity due to drinking arsenic-contaminated water has been one of the worst environmental health hazards, affecting eight districts of Nepal and India since the early eighties. Methods: Detailed clinical examination and investigation of 248 such patients revealed protean clinical manifestations of such toxicity. Over and above hyperpigmentation and keratosis, weakness, anaemia, burning sensation of eyes, solid swelling of legs, liver fibrosis, chronic lung disease, gangrene of toes, neuropathy, and skin cancer are some of the other manifestations. A cross-sectional survey involving 7683 participants of all ages was conducted in an arsenic-affected region between April 2006 and March 2007. Results: Out of a population of 7683 surveyed, 3467 and 4216 people consumed water containing As below and above 0.05 mg/L, respectively. Except for abdominal pain, the prevalence of all other clinical manifestations tested (e.g., pigmentation, keratosis, hepatomegaly, weakness, nausea, lung disease and neuropathy) were found to be significantly higher in As exposed people (water As >0.05 mg/L) compared to control population (water As level <0.05 mg/L). The prevalence of pigmentation and keratosis, hepatomegaly, chronic respiratory disease and weakness rose significantly with increasing arsenic concentrations in drinking water. The respiratory effects were most pronounced in individuals with high arsenic water concentrations who also had skin lesion. Therapy with chelating agent DMSA was not found to be superior to placebo effect. However, therapy with DMPS caused significant improvement of clinical condition of chronic arsenicosis patients as evidenced by significant reduction of total clinical scores from 8.90 ± 2.84 to 3.27 ± 1.73; P < 0.0001. Efficacy of specific chelation therapy for patients suffering from chronic As toxicity has further need to be fully substantiated. However, supportive treatment could help in reducing many symptoms of the patients. Conclusions: Treatment in hospital with good nutritious diet has been found to reduce symptom score in a subset of placebo treated patients during the course of DMSA and DMPS trial. People should be advised to stop drinking As contaminated water or avoid As exposure from any other source. The various clinical manifestations should be treated symptomatically.",
Arsenic,1019282,"Investigations of the metabolites of the trypanocidal drug melarsoprol Abstract: <strong>BACKGROUND: </strong>Melarsoprol remains the first-choice drug for trypanosomiasis (human African sleeping sickness). To contribute to the sparse pharmacologic data and to better understand the cause of the frequent serious adverse reactions, we investigated the metabolism of this 50-year-old organoarsenic compound.<br /><br /><strong>RESULTS: </strong>The half-life of melarsoprol determined by HPLC was &lt;1 hour compared with 35 hours determined by bioassay and atomic absorption spectroscopy, indicating the existence of active metabolites. One metabolite, melarsen oxide, was identified by ultraviolet HPLC after incubation of melarsoprol with microsomes. The maximum plasma concentration of melarsenoxide was reached 15 minutes after administration; the clearance was 21.5 mL/min/kg and the half-life of free melarsen oxide was 3.9 hours. Either melarsen oxide or a yet-undiscovered active metabolite is irreversibly bound to proteins, as shown by ultrafiltration, precipitation experiments, and atomic absorption spectroscopy. Because of the poor pharmaceutical properties of melarsoprol, the therapeutic potential of melarsen oxide was investigated. In a rodent model of acute infection, 20 of 20 mice were cured (0.1 to 1 mg/kg intravenously or 2.2 mg/kg intraperitoneally). In a rodent model of central nervous system infection, five of six mice survived for more than 180 days (5 mg/kg intravenously), indicating a sufficient melarsen oxide penetration across the blood-brain barrier.<br /><br /><strong>CONCLUSION: </strong>The prospects for the future of trypanosomiasis treatment are deplorable. Investigations on the improvement of the use of the old drugs are therefore required. The results of this study may build a basis for further research on the cause of severe adverse reactions.",
Arsenic,628237,"Subchronic exposure to arsenic through drinking water alters expression of cancer-related genes in rat liver Abstract: Although arsenic exposure causes liver disease and/or hepatoma, little is known about molecular mechanisms of arsenic-induced liver toxicity or carcinogenesis. We investigated the effects of arsenic on expression of cancer-related genes in a rat liver following subchronic exposure to sodium arsenate (1, 10, 100 ppm in drinking water), by using real-time quantitative RT-PCR and immunohistochemical analyses. Arsenic accumulated in the rat liver dose-dependently and caused hepatic histopathological changes, such as disruption of hepatic cords, sinusoidal dilation, and fatty infiltration. A 1-month exposure to arsenic significantly increased hepatic mRNA levels of cyclin D1 (10 ppm), ILK (1 ppm), and p27(Kip1) (10 ppm), whereas it reduced mRNA levels of PTEN (1 ppm) and beta-catenin (100 ppm). In contrast, a 4-month arsenic exposure showed increased mRNA expression of cyclin D1 (100 ppm), ILK (1 ppm), and p27(Kip1) (1 and 10 ppm), and decreased expression of both PTEN and beta-catenin at all 3 doses. An immunohistochemical study revealed that each protein expression accords closely with each gene expression of mRNA level. In conclusion, subchronic exposure to inorganic arsenate caused pathological changes and altered expression of cyclin D1, p27(Kip1), ILK, PTEN, and beta-catenin in the liver. This implies that arsenic liver toxicity involves disturbances of some cancer-related molecules.",
Arsenic,2347610,"Breeding near a landfill may influence blood metals (Cd, Pb, Hg, Fe, Zn) and metalloids (Se, As) in white stork (Ciconia ciconia) nestlings Abstract: Cadmium, lead, mercury, selenium, iron, zinc and arsenic levels were measured in blood samples from 59 free-ranging white stork nestlings from colonies located in three different environmental conditions in Western Spain. The reference colony was situated in &quot;Llanos de Cáceres y Sierra de Fuentes&quot;, an Area of Special Interest for Bird Protection. A second colony was located close to (4.9 km) an urban landfill and a third one was close to both an intensive agricultural area and an urban landfill (1.5 km). Blood samples were diluted and elemental analysis was performed using inductively coupled plasma mass spectrometer. In all cases, the essential metals zinc and iron were found at the highest mean concentrations followed by lead &gt; selenium &gt; mercury &gt; arsenic &gt; cadmium. Regarding toxic metals, the highest concentrations were found for lead (ranging from 23.27 to 146.4 µg/L) although in all cases the concentrations were lower than those considered to cause subclinical effects. The metals levels detected in the chick's blood were not related to the previously reported levels in the soil next to the colonies, which may indicate that landfills are the main source of metals in white stork nestlings. The present data showed that metal levels in white stork chicks may be influenced by the use of landfills as feeding areas by the parents. However, more studies on the metal content in the feed of white stork and the influence of the distance to the landfill are necessary to establish the causality of these findings.",
Arsenic,1021492,"Atherosclerosis induced by arsenic in drinking water in rats through altering lipid metabolism Abstract: Arsenic in drinking water is a global environmental health problem, and the exposure may increase cardiovascular and cerebrovascular diseases mortalities, most likely through causing atherosclerosis. However, the mechanism of atherosclerosis formation after arsenic exposure is still unclear. To study the mechanism of atherosclerosis formation after arsenic exposure and explore the role of high cholesterol diet (HCD) in this process, we fed spontaneous hypertensive rats and Wistar Kyoto rats with basal diet or HCD and provided with them drinking water containing arsenic at different ages and orders for 20 consecutive weeks. We measured high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), total cholesterol, triglycerides, heat shock protein 70 (HSP 70), and high sensitive C-reactive protein (hs-CRP) at predetermined intervals and determined expressions of cholesteryl ester transfer protein-1 (CETP-1) and liver X receptor ? (LXR?) in the liver. Atherosclerosis was determined by examining the aorta with hematoxylin and eosin stain. After 20 weeks, we found arsenic, alone or combined with HCD, may promote atherosclerosis formation with transient increases in HSP 70 and hs-CRP. Early combination exposure decreased the HDL-C/LDL-C ratio without changing the levels of total cholesterol and triglyceride until 30 weeks old. Both CETP-1 and LXR? activities were suppressed, most significantly in early combination exposure. In conclusion, arsenic exposure may induce atherosclerosis through modifying reverse cholesterol transport in cholesterol metabolism and suppressing LXR? and CEPT-1 expressions. For decreasing atherosclerosis related mortality associated with arsenic, preventing exposure from environmental sources in early life is an important element.",
Arsenic,194208,"The vascular system as a target of metal toxicity Abstract: Vascular system function involves complex interactions among the vascular endothelium, smooth muscle, the immune system, and the nervous system. The toxic metals cadmium (Cd), arsenic (As), and lead (Pb) can target the vascular system in a variety of ways, ranging from hemorrhagic injury to subtle pathogenic remodeling and metabolic changes. Acute Cd exposure results in hemorrhagic injury to the testis, although some strains of animals are resistant to this effect. A comparison of Cd-sensitive with Cd-resistant mouse strains showed that expression of the Slc39a8 gene, encoding the ZIP8 transporter, in the testis vasculature endothelium is responsible for this difference. Endogenously, ZIP8 is a Mn2+/HCO3–symporter that may also contribute to Cd damage in the kidney. Chronic Cd exposure is associated with various cardiovascular disorders such as hypertension and cardiomyopathy and it is reported to have both carcinogenic and anticarcinogenic activities. At noncytotoxic concentrations of 10–100nM, Cd can inhibit chemotaxis and tube formation of vascular endothelial cells. These angiostatic effects may be mediated through disruption of vascular endothelial cadherin, a Ca2+-dependent cell adhesion molecule. With regard to As, ingestion of water containing disease-promoting concentrations of As promotes capillarization of the liver sinusoidal endothelium. Because capillarization is a hallmark precursor for liver fibrosis and contributes to an imbalance of lipid metabolism, this As effect on hepatic endothelial cells may be a pathogenic mechanism underlying As-related vascular diseases. With regard to Pb, perinatal exposure may cause sustained elevations in adult blood pressure, and genetically susceptible animals may show enhanced sensitivity to this effect. Taken together, these data indicate that the vascular system is a critical target of metal toxicity and that actions of metals on the vascular system may play important roles in mediating the pathophysiologic effects of metals in specific target organs.",
Arsenic,1340017,"Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis Abstract: The mechanisms by which environmental toxicants alter developmental processes predisposing individuals to adult onset chronic disease are not well-understood. Transplacental arsenic exposure promotes atherogenesis in apolipoprotein E-knockout (ApoE(-/-)) mice. Because the liver plays a central role in atherosclerosis, diabetes and metabolic syndrome, we hypothesized that accelerated atherosclerosis may be linked to altered hepatic development. This hypothesis was tested in ApoE(-/-) mice exposed to 49 ppm arsenic in utero from gestational day (GD) 8 to term. GD18 hepatic arsenic was 1.2 µg/g in dams and 350 ng/g in fetuses. The hepatic transcriptome was evaluated by microarray analysis to assess mRNA and microRNA abundance in control and exposed pups at postnatal day (PND) 1 and PND70. Arsenic exposure altered postnatal developmental trajectory of mRNA and microRNA profiles. We identified an arsenic exposure related 51-gene signature at PND1 and PND70 with several hubs of interaction (Hspa8, IgM and Hnf4a). Gene ontology (GO) annotation analyses indicated that pathways for gluconeogenesis and glycolysis were suppressed in exposed pups at PND1, and pathways for protein export, ribosome, antigen processing and presentation, and complement and coagulation cascades were induced by PND70. Promoter analysis of differentially-expressed transcripts identified enriched transcription factor binding sites and clustering to common regulatory sites. SREBP1 binding sites were identified in about 16% of PND70 differentially-expressed genes. Western blot analysis confirmed changes in the liver at PND70 that included increases of heat shock protein 70 (Hspa8) and active SREBP1. Plasma AST and ALT levels were increased at PND70. These results suggest that transplacental arsenic exposure alters developmental programming in fetal liver, leading to an enduring stress and proinflammatory response postnatally that may contribute to early onset of atherosclerosis. Genes containing SREBP1 binding sites also suggest pathways for diabetes mellitus and rheumatoid arthritis, both diseases that contribute to increased cardiovascular disease in humans.",
Arsenic,759701,"Arsenic (+ 3 oxidation state) methyltransferase and the methylation of arsenicals in the invertebrate chordate Ciona intestinalis Abstract: Biotransformation of inorganic arsenic (iAs) involves methylation catalyzed by arsenic (+ 3 oxidation state) methyltransferase (As3mt) yielding mono-, di-, and trimethylated arsenicals. To investigate the evolution of molecular mechanisms that mediate arsenic biotransformation, a comparative genomic approach focusing on the invertebrate chordate Ciona intestinalis was used. Bioinformatic analyses identified an As3mt gene in the C. intestinalis genome. Constitutive As3mt RNA expression was observed in heart, branchial sac, and gastrointestinal tract. Adult animals were exposed to 0 or 1 ppm of iAs for 1 or 5 days. Steady-state As3mt RNA expression in the gastrointestinal tract was not modulated significantly by 5 days of exposure to iAs. Tissue levels of iAs and its methylated metabolites were determined by hydride generation-cryotrapping-gas chromatography-atomic absorption spectrometry. At either time point, exposure to iAs significantly increased concentrations of iAs and its methylated metabolites in tissues. After 5 days of exposure, total speciated arsenic concentrations were highest in branchial sac (3705 ng/g), followed by heart (1019 ng/g) and gastrointestinal tract (835 ng/g). At this time point, the sum of the speciated arsenical concentrations in gastrointestinal tract and heart equaled or exceeded that of iAs; in branchial sac, iAs was the predominant species present. Ciona intestinalis metabolizes iAs to its methylated metabolites, which are retained in tissues. This metabolic pattern is consistent with the presence of an As3mt ortholog in its genome and constitutive expression of the gene in prominent organs, making this basal chordate a useful model to examine the evolution of arsenic detoxification.",
Arsenic,1146068,"Chronic arsenic exposure and adverse pregnancy outcomes in Bangladesh Abstract: ntroduction: Chronic arsenic exposure through drinking water has the potential to cause adverse pregnancy outcomes, though the association is not conclusive. This cross sectional study was carried out in twothree arsenic affected districts of Bangladesh to determine the association between chronic arsenic exposure through drinking water and spontaneous abortion, stillbirth and neonatal death. Methods: In this cross-sectional study, 533 married, non-smoking females of reproductive age (range 15 to 49 years) with a history of at least one pregnancy, who had been living in the study area since their marriage and drank water from the respective tube well prior to and during the pregnancy were interviewed. Information on sociodemographics, drinking water use, occupation and adverse pregnancy outcomes were obtained through a structured pretested interviewer-administered questionnaire. Out of 2138 tube wells, 203198 water samples were measured using UV/Visible spectrophotometry method while 15 were measured by flow-injection hydride generation atomic absorption spectrometry (FIHG-AAS). Results: A total of 533 female participated in this study. Their mean age was 31.22 years (standard deviation [SD] = 6.44) and the average duration of arsenic exposure of the participants was 8.11 years (SD = 7.32), median duration of exposure was 7 years. Out of the study subjects, 257 (48%) of the study participants did not receive any formal education. The majority of them (51%) got married before the age of 16-years. The mean number of pregnancies was 3.72 (SD = 1.79) and mean number of live births was 3.48 (SD = 1.65). Melanosis was observed among 51 (10%) and keratosis was observed among 43 (8%) participants. The mean and median arsenic concentration of the tube well drinking water of the study participants was 279(SD = 355) [mu]g/L and 116 ppb[mu]g/L respectively, ranging from non-detectable level to 1710 ppb[mu]g/L. 356 (67%) participants were exposed to arsenic at more than 50 ppb[mu]g/L, the recommended level of arsenic in drinking water for Bangladesh. Overall incidence of spontaneous abortion, stillbirth and neonatal death in this study were found as 59.61/1000 live birth, 35.55 /1000 live birth and 49.31 /1000 live birth respectively. Excess risks for spontaneous abortion, stillbirth and neonatal death were observed among the participants exposed to increasing concentrations of arsenic in drinking water, after adjusting for participant's education, age at marriage, antenatal care and parity. The odds ratio (OR) for spontaneous abortion, stillbirth and neonatal death was 1.93 (95% Confidence Interval [CI]: 1.11, 3.37), 1.82 (95% CI: 0.94, 3.51) and 1.89 (95% CI: 1.02, 3.53) respectively for females drinking water with >50ppb[mu]g/L compared to [pounds]50ppb[mu]g/L arsenic concentration. These risks are both clinically and statistically significant except stillbirth. There was, however, a statistically significant dose-response association between increasing arsenic concentration and stillbirth (p = 0.02), neonatal death (p = 0.01).",
Arsenic,2149318,Identifying Rice Arsenic Stress Response Pathways Based on Molecular Interaction Network Abstract: ,
Arsenic,2141408,"Arsenic exposure of rural populations from the Rift Valley of Ethiopia as monitored by keratin in toenails Abstract: Arsenic (As) contamination of drinking water is a worldwide phenomenon whose effect among vulnerable and rural communities in the Rift Valley of Ethiopia in eastern Africa is not well studied. This study examines As exposure and bioaccumulation from drinking water by monitoring human keratin in the form of toenails from exposed populations. Groundwater samples from drinking water wells (n=34) were collected along with toenail samples (n=58) from local communities and were analyzed for trace metals including As by inductively coupled plasma mass spectrometry (ICP-MS). Of the total number of wells tested, 53% had As level above the WHO maximum contamination level of 10?p.p.b. Arsenic in toenails was significantly correlated to corresponding drinking water (r=0.72; R(2)=0.52; P&lt;0.001). This correlation improves for drinking water with As concentrations above 2?p.p.b. (r=0.74; R(2)=0.54; P&lt;0.001). Male minors (&lt;18 years old) were found to have greater nail-As concentrations compared with adults consuming equal amounts of As (P&lt;0.05). Estimated As dose specifically from drinking water sources was also associated with nail concentrations (P&lt;0.01). We suggest that As measurement in nails could be a reliable method for detecting As exposure in residents living in rural areas.Journal of Exposure Science and Environmental Epidemiology advance online publication, 6 November 2013; doi:10.1038/jes.2013.77.",
Arsenic,2149157,"The Adverse Health Consequences of the Use of Multiple Performance-Enhancing Substances-- A Deadly Cocktail Abstract: Context:The harmful consequences of abuse of performance-enhancing substances (PESs), stimulants, and masking agents among athletes, recreational weight lifters, and physical trainers are common. However, the adverse health outcomes with severe unexpected and dramatic consequences are under-recognized or under-reported at the expense of short-term glory or body-image effects, especially in elite sports.Objective:We report the case of a recreational weight lifter/physical trainer to help summarize the adverse health consequences and outcomes of polypharmacy among athletes and growing subsets in our population engaged in physical/fitness training. We show that in addition to the risk inherent to &quot;stacking&quot; of PESs, the users are predisposed to harmful consequences, including risk of exposure to toxic contaminants.Design and Setting:A previously healthy man with chronic use of multiple PESs, stimulants, and masking agents presented to a tertiary-care hospital with jaundice and mild hepatitis with rapid progression into liver and multisystem organ failure. This is followed by a brief overview of the specific toxicity (arsenic) and PESs that contributed to the poor outcome in this case.Conclusion:Surreptitiously or self-administered cocktails of potential PESs including anabolic substances, emerging classes of GH-releasing peptides or androgen precursors, stimulants, and masking agents could lead to adverse consequences including early mortality, multisystem pathology, and unmasked/accelerated malignancy, and could even expose/predispose users to extreme danger from contaminants. This cautionary case reinforces the need to increase awareness and highlights the challenges that testing agencies, regulators, and clinicians face in the fast-developing licit/illicit trade of these products.",
Arsenic,1248785,"Pollutant concentrations in placenta Abstract: Unborn children are exposed to environmental pollutants via the placenta, and there is a causal relationship between maternal intake of pollutants and fetal exposure. Placental examination is an effective way for acquiring data for estimating fetal exposure. We analyzed the concentrations of 104 congeners of persistent organic pollutants, seven organotin compounds, five heavy metals, and methylmercury in 130 randomly selected placentas. Additionally, we examined similarities between pollutant concentrations by analyzing correlations between their placental concentrations. Our results yield new information for conducting contaminant risk assessments for the prenatal period. Out of the 117 individual persistent organic pollutants or metals assayed, 46 could be detected in more than half of the placentas. Moreover, dichlorodiphenyldichloroethylene (p,p'-DDE) was found in all placentas. The data indicates that fetal exposure to dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), p,p'-DDE, and methylmercury depends on the mother's parity, and age. We also conclude that sources of the above four pollutants are similar but differ from the sources of polybrominated diphenyl ethers.",
Arsenic,1355532,Carcinogenicity of inorganic arsenics and its mechanistic concepts Abstract: ,
Arsenic,627809,"Study of inorganic arsenic methylation by rat liver in vitro: Relevance for the interpretation of observations in man Abstract: The biotransformation of inorganic arsenic by rat liver in vitro leads to the production of a monomethylated and a dimethylated arsenic derivative, measured by flameless atomic absorption as monomethylarsonic (MMA) and dimethylarsinic (DMA) acids respectively. The methylating activity is localized in the cytosol and accepts only As3+ as substrate. Its optimum pH lies between 7.5 and 8.0, and reduced glutathione (10(-2)M) is required for full activity. S-Adenosylmethionine is the essential methyl group donor and corrinoïd derivatives act synergistically. An excess of substrate and the addition of mercuric ions prevent the formation of the dimethylated arsenic derivative without affecting that of the monomethylated compound. This indicates that two different enzymatic activities are involved in the methylation of inorganic arsenic in mammals. Previous observations in man (Buchet et al. 1981 b, 1984) and the results of the present study suggest that DMA production results from the subsequent methylation of the MMA precursor, although the possibility that metabolites are also produced by two completely independent pathways cannot yet be conclusively rejected. The kinetics of MMA and DMA production provide an explanation for the observations that in volunteers given increasing amounts of As3+, the urinary excretion of DMA levels off faster than that of MMA and in patients acutely intoxicated with As3+, several days may elapse before DMA becomes the preponderant metabolite. The results of the present study also suggest that the reduction of MMA production associated with an increased synthesis of DMA found in patients with liver diseases given a standard dose of As3+ might be due to a reduction of As3+ uptake by the liver cells.",
Arsenic,1352080,"Non-heme induction of heme oxygenase-1 does not alter cellular iron metabolism Abstract: The catabolism of heme is carried out by members of the heme oxygenase (HO) family. The products of heme catabolism by HO-1 are ferrous iron, biliverdin (subsequently converted to bilirubin), and carbon monoxide. In addition to its function in the recycling of hemoglobin iron, this microsomal enzyme has been shown to protect cells in various stress models. Implicit in the reports of HO-1 cytoprotection to date are its effects on the cellular handling of heme/iron. However, the limited amount of uncommitted heme in non-erythroid cells brings to question the source of substrate for this enzyme in non-hemolytic circumstances. In the present study, HO-1 was induced by either sodium arsenite (reactive oxygen species producer) or hemin or overexpressed in the murine macrophage-like cell line, RAW 264.7. Both of the inducers elicited an increase in active HO-1; however, only hemin exposure caused an increase in the synthesis rate of the iron storage protein, ferritin. This effect of hemin was the direct result of the liberation of iron from heme by HO. Cells stably overexpressing HO-1, although protected from oxidative stress, did not display elevated basal ferritin synthesis. However, these cells did exhibit an increase in ferritin synthesis, compared with untransfected controls, in response to hemin treatment, suggesting that heme levels, and not HO-1, limit cellular heme catabolism. Our results suggest that the protection of cells from oxidative insult afforded by HO-1 is not due to the catabolism of significant amounts of cellular heme as thought previously.",
Arsenic,2064296,"The vibration characterization of synthetic crystalline lead hydrogen arsenite chloride precipitates Pb2(HAsO3)Cl2-implications of solidification of As (III) and Pb (II) Abstract: The lead hydrogen arsenite chloride precipitates (Pb2(HAsO3)Cl2) are synthesized hydrothermally due to its structure trap for lead and arsenic. The synthetic precipitates have well-developed crystalline. The crystals of lead hydrogen arsenite chloride have a series of obvious IR bands at 790, 721, 645, 589 and 554cm(-1). These bands are assigned to the Ag mode of As-O stretching vibration (790), the antisymmetric stretch of As-OH (721), Ag modes (554 and 589) and E1g (645) of the symmetric deformation (?1 and ?3) of AsO3 unit. The Raman bands at 782, 723, 586, 559cm(-1) are attributed to As-O stretching vibration (?1) and the symmetric deformation (?1 and ?3), of which the positions and assignments display in accordance with IR result. The most intense Raman band is found in 814cm(-1) and is attributed to the Ag mode of ?1 symmetric stretching vibration of AsO3 unit, which is not active in IR. The SEM image shows that the precipitates have needle morphology.",
Arsenic,1020141,"Arsenic-related health problems among hospital patients in southern Bangladesh Abstract: To assess the health effects of arsenic poisoning and to determine the relationship among duration and severity of skin lesions, exposure dose of arsenic, and nutritional status of people, 150 patients attending the Dermatology Outpatients Department of Sher-e-Bangla Medical College Hospital, Barisal, Bangladesh, were included in this cross-sectional study. The study was conducted during January-December 2000. Records of patients were collected prospectively using a pre-tested questionnaire, which included information on demography, sources of water for drinking and cooking, duration and amount of drinking-water obtained from shallow tubewells, clinical presentations, complications, and physical and laboratory findings. Water samples from tubewells currently being used by individual patients were examined. Nine percent of the patients were unaware that arsenic-contaminated water causes diseases. Due to lack of alternative water supplies, 25% of the subjects were still drinking water from contaminated tubewells. About 18% did not complain of any clinical symptoms, except that their skin lesions were ugly-looking, and 82% had moderate or severe skin lesions. Thirty-one percent of the water samples had arsenic concentrations 10-fold higher than the permissible limit of 0.05 mg/L in Bangladesh and 50-fold higher than the WHO guideline value of 0.01 mg/L. The mean arsenic concentration in water was significantly associated with the severity of disease. Body mass index correlated inversely (r = -0.298, p = 0.013) with the duration of disease after controlling for age. The findings suggest the need to enhance public awareness on negative health effects of arsenic poisoning in rural Bangladesh. From a public-health perspective, effective intervention strategies need to be developed to curb the exposure, strengthen rapid diagnostic facilities, establish effective treatment facilities in rural areas, and improve the nutritional status of people.",
Arsenic,628359,"In-vitro cytotoxic and genotoxic effects of arsenic trioxide on human leukemia (HL-60) cells using the MTT and alkaline single cell gel electrophoresis (Comet) assays Abstract: Although arsenic trioxide (ATO) has been the subject of toxicological research, in vitro cytotoxicity and genotoxicity studies using relevant cell models and uniform methodology are not well elucidated. Hence, the aim of the present study was to evaluate the cytotoxicity and genotoxicity induced by ATO in a human leukemia (HL-60) cell line using the MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and alkaline single cell gel electrophoresis (Comet) assays, respectively. HL-60 cells were treated with different doses of ATO for 24 h prior to cytogenetic assessment. Data obtained from the MTT assay indicated that ATO significantly (P < 0.05) reduced the viability of HL-60 cells in a dose-dependent manner, showing a LD(50) value of 6.4 +/- 0.6 microg/mL. Data generated from the comet assay also indicated a significant dose-dependent increase in DNA damage in HL-60 cells associated with ATO exposure. We observed a significant increase (P < 0.05) in comet tail-length, tail arm and tail moment, as well as in percentages of DNA cleavage at all doses tested, showing an evidence of ATO-induced genotoxic damage in HL-60 cells. This study confirms that the comet assay is a sensitive and effective method to detect DNA damage caused by heavy metals like arsenic. Taken together, our findings suggest that ATO exposure significantly (P < 0.05) reduces cellular viability and induces DNA damage in HL-60 cells as assessed by MTT and alkaline single cell gel electrophoresis assays, respectively.",
Arsenic,1519078,"Effect of nicotine pretreatment on arsenic-induced oxidative stress in male Wistar rats Abstract: Humans are commonly exposed to nicotine, one of the most important lifestyle chemicals. The occurrence of high levels of arsenic in the groundwater of the southeast region of Asia has received much attention in the past decade and has become a global health concern. Predominant occurrence of both these chemicals and ease of their human exposure led us to investigate the effect of nicotine, a major tobacco alkaloid, on arsenic toxicity. Adult male rats were pre-exposed to two different doses of nicotine (0.75 and 3 mg/kg, intraperitoneally) for 7 days followed by 30 days of arsenic exposure (50 ppm sodium arsenite in drinking water). Nicotine pre-exposure resulted in an increased brain arsenic accumulation and a decreased liver arsenic concentration. Arsenic also caused a significant oxidative stress in the blood, brain and liver of the exposed rats. Glutathione-S-transferase, a phase II enzyme, was inhibited by both arsenic and nicotine but no such inhibition was noted in arsenic-treated animals pre-exposed to nicotine. Upon nicotine pre-exposure, brain acetylcholinesterase increased, while monoamine oxidase (MAO) decreased. The toxic effects of MAO significantly attenuated with nicotine pre-exposure. The present study suggests that nicotine may not be the major contributing factor for the previously reported synergistic toxic interaction between tobacco and arsenic. Nicotine pre-exposure in arsenic-exposed animals revealed interesting toxicokinetics and oxidative stress modulating interactions in the brain and liver of rats, which requires further exploration.",
Arsenic,1380318,Human exposures to chemicals through food chains an uncertainty analysis Abstract: ,
Arsenic,2149181,Comment on &quot;New Clues to the Local Atomic Structure of Short-Range Ordered Ferric Arsenate from Extended X-ray Absorption Fine Structure Spectroscopy&quot Abstract: ,
Arsenic,2347815,"Source and migration of dissolved manganese in the Central Nile Delta Aquifer, Egypt Abstract: Dissolved metals in waters in shallow deltaic sediments are one of the world's major health problems, and a prime example is arsenic contamination in Bangladesh. The Central Nile Delta Aquifer, a drinking water source for more than 6 million people, can have high concentrations of dissolved manganese (Mn). Standard hydrochemical analyses coupled with sequential chemical extraction is used to identify the source of the Mn and to identify the probable cause of the contamination. Fifty-nine municipal supply wells were sampled and the results compared with published data for groundwaters and surface waters. Drill cuttings from 4 wells were collected and analyzed by sequential chemical extraction to test the hypothesized Mn-generating processes. The data from this research show that the Mn source is not deep saline water, microbial reduction of Mn oxides at the production depth, or leakage from irrigation drainage ditches. Instead, Mn associated with carbonate minerals in the surficial confining layer and transported down along the disturbed well annulus of the municipal supply wells is the likely source. This analysis provides a basis for future hydrogeological and contaminant transport modeling as well as remediation-modification of well completion practices and pumping schedules to mitigate the problem.",
Arsenic,2346001,"Potential nonmonotonous association between di(2-ethylhexyl) phthalate (DEHP) exposure and atopic dermatitis in Korean children Abstract: <strong>BACKGROUND: </strong>Concerns have emerged about the adverse effect of phthalates on human health.<br /><br /><strong>OBJECTIVES: </strong>The aim of this study was to investigate the association between DEHP exposure and atopic dermatitis in Korean children, focusing on the potential dose-response relationship.<br /><br /><strong>METHODS: </strong>A matched case-control study was conducted from May to October, 2012. Subjects from 3 to 6 years were recruited from kindergartens and daycare centers in Seoul, Korea. Clinical diagnosis for atopic dermatitis was done by dermatologists. A total of 224 cases and 224 age- and gender-matched controls were included. The levels of two phthalate metabolites [mono(2-ethyl-5-hydrohexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP)] of di(2-ethylhexyl) phthalate (DEHP) in the urine samples were measured.<br /><br /><strong>RESULTS: </strong>The effect of DEHP was different by age, and an increased risk for atopic dermatitis was associated with DEHP at age 3 (OR 2.51, 95% CI 1.02, 6.20). The association was in the opposite direction in the other age groups although there was no statistical significance. The effect of DEHP on atopic dermatitis was observed differently by the level of the body burden. The predicted risk for atopic dermatitis based on the results of multiple logistic regression analysis showed a nonmonotonous association between the level of DEHP and the risk of atopic dermatitis (u-shaped).<br /><br /><strong>CONCLUSIONS: </strong>This finding might suggest that the effect of DEHP on atopic dermatitis may be different according to the exposure level or age of the subject. Further longitudinal investigations with a suitable design to investigate the nonmonotonous association should be encouraged.",
Arsenic,2064160,INVESTIGATIONS ON ARSENIC MOBILITY CHANGES IN RIZOSPHERE OF TWO FERNS SPECIES USING DGT TECHNIQUE Abstract: ,
Arsenic,1375772,"Nuclear and nucleolar localization of the 72,000-dalton heat shock protein in heat-shocked mammalian cells Abstract: The intracellular location of the major induced mammalian heat shock (or stress) protein (Mr = 72,000) has been determined by both biochemical and immunological methods. This protein, shown here to be comprised of at least three structurally related isoforms, is produced at high levels within 30 min to 1 h following heat treatment of cells. Biochemical fractionation of cells grown under heat shock showed that following its synthesis a portion of the 72,000-Da protein (and its isoforms) becomes associated with the nucleus while some remains in the cytoplasm. Indirect immunofluorescence studies using antiserum directed against the major isoforms of the 72,000-Da protein were carried out in normal and heat-shocked cells as well as in cells grown under stress by exposure to either an amino acid analogue or to sodium arsenite. Diffuse cytoplasmic and nuclear staining was observed in cells grown at 37 degrees C. In cells grown under heat shock conditions, both the cytoplasmic staining and the nuclear staining were found to increase with the nuclear staining consisting of both granular and patch-like structures, the latter being coincident with phase-dense nucleoli. In the case of cells exposed to amino acid analogues or to sodium arsenite, only cytoplasmic and to a lesser extent nuclear staining was observed, i.e. no localized nucleolar fluorescence was observed. Following return of heat shock-treated cells to normal growth temperatures, both the synthesis of the 72,000-Dalton stress protein and its nucleolar staining were found to diminish.",
Arsenic,1015814,"Pharmaceutical development of the novel arsenical based cancer therapeutic GSAO for Phase I clinical trial Abstract: The novel organoarsenical GSAO, 4-(N-(S-glutathionylacetyl)amino) phenylarsonous acid, has potential anti-angiogenic capability with application in cancer where tumour metastasis relies on neo-vascularisation. As GSAO arsenic is trivalent, the arsenoxide moiety reacts with appropriately spaced cysteine residues on adenine nucleotide translocase (ANT) mitochondrial membrane protein. Molecular oxidation of the arsenic to the pentavalent structure, as in the degradant GSAA (4-(N-(S-glutathionylacetyl)amino) phenylarsonic acid), prevents sulphydryl interaction and risks abolition of activity. We report here on formulation studies aiming to produce a parenteral product with the primary objective of restricting GSAA transformation from GSAO to protect maximal potency of the molecule. Successful anti-oxidant strategy primarily came from pH control. The presence of glycine was proposed to form a stabilising five-membered oxazarsolidinone ring with arsenoxide and this was investigated using potentiometric assays. We report on these tritration studies identifying a pK(a) of 8.2 associated with an As-OH, but not confirming ring presence. An original clinical trial pharmaceutical was successfully realised by lyophilisation of 50mg/mL GSAO in 100mM glycine solution, pH 7 to obtain a 48-month shelf life for the freeze-dried vials. The Phase I clinical study is ongoing in patients with solid tumours refractory to standard therapy.",
Arsenic,1000194,"Geochemistry and mobilization of arsenic in Shuklaganj area of Kanpur-Unnao district, Uttar Pradesh, India Abstract: The level of arsenic (As) contamination and the geochemical composition of groundwater in Shuklaganj area located on the banks of the Ganges Delta of Kanpur-Unnao district were elucidated. Samples (n?=?59) were collected from both India Mark II hand pumps (depth, 30-33 m) and domestic hand pump tube wells (10-12 m) located within 5 km from the banks of Ganges. Samples were analyzed for various parameters, including total inorganic As, sulfate, nitrate, alkalinity, ammonia, and iron. Hydrochemistry of the groundwater aquifer was studied through the trilinear plots between monovalent and divalent cations and anions. In Indian mark II hand pumps, arsenic concentration ranged from below detection limit to 448 ?g/L. Most of the samples contained both As(III) and As(V). The pH of the samples ranged from 7.1 to 8.2. Except for a few, most of the samples were reducing in nature as evident by their negative oxidation reduction potentials. A positive correlation for arsenic with iron, ammonia, and dissolved organic carbon shows the probability of biodegradation of organic matter and reductive dissolution of Fe oxyhydroxide processes to leach As in aquifers. For confirmation of the suggested arsenic mobilization mechanism, the presence and absence of sulfate-reducing bacteria and iron-reducing bacteria were also tested.",
Arsenic,1579299,"Draft Genome Sequence of Ochrobactrum pseudogrignonense Strain CDB2, a Highly Efficient Arsenate-Resistant Soil Bacterium from Arsenic-Contaminated Cattle Dip Sites Abstract: We report the 4.97-Mb draft genome sequence of a highly efficient arsenate-resistant bacterium, Ochrobactrum sp. strain CDB2. It contains a novel arsenic resistance (ars) operon (arsR-arsC1-ACR3-arsC2-arsH-mfs) and two non-operon-associated ars genes, arsC3 and arsB. The genome information will aid in the understanding of the arsenic resistance mechanism of this and other bacterial species.",
Arsenic,1391128,"The Effects Of Cupric Dimethyldithiocarbamate On Maternal And Fetal Long-Evans Rats Abstract: In 1996 the American Wood Preservers? Association standardized wood preservative solutions that contain new copper based compounds. Studies suggest that cupric dimethyldithiocarbamate (CDCC), a recently introduced alternative to chromated copper arsenic, induces neuronal cytotoxicity. Data from this lab has shown that CDCC causes a dose dependent decrease in cell viability in rat hippocampal astrocytes in culture, accompanied by morphological deterioration and cellular blebbing visualized by SEM. Bioaccumulation of Cu in tissues has been linked to oxidative damage and lipid peroxidation. In this study, pregnant Long Evans rats (220-270g) were dosed at 50 and 75ppm by oral gavage. Following parturition, maternal and newborn rats were euthanized, brain tissue was either fixed for microscopy or snap frozen in liquid nitrogen and processed for immunoblots and graphite furnace atomic absorbance spectrophotometry (GFAAS). Induction of stress proteins, lipid hydroperoxidation and morphological damage to maternal hippocampi and maternal and newborn whole brain tissues in treated vs. control animals were seen. Immunoblots on brain samples from maternal and newborn rats using anti-Hsp-70 monoclonal antibody and anti-HO-1 polyclonal antibody demonstrated an increase of stress proteins in maternal and newborn whole brain and maternal hippocampi. Immunoblots also revealed 4HNE protein adducts in maternal hippocampi and maternal and newborn whole brain. It is concluded that CDCC at 50 and 75ppm induces stress proteins as well as producing hydroperoxidative damage. GFAAS used for detection of Cu concentration showed dose dependent increase in the bioaccumulation of the transition metal in these tissues. This suggests a correlation between Cu concentration, stress protein induction and peroxidative damage.",
Arsenic,627598,"Arsenic induced apoptosis in rat liver following repeated 60 days exposure Abstract: BACKGROUND: Accumulation of the wide spread environmental toxin arsenic in liver results in hepatotoxcity. Exposure to arsenite and other arsenicals has been previously shown to induce apoptosis in certain tumor cell lines at low (1-3 microM) concentration. AIM: The present study was focused to elucidate the role of free radicals in arsenic toxicity and to investigate the nature of in vivo sodium arsenite induced cell death in liver. METHODS: Male wistar rats were exposed to arsenite at three different doses of 0.05, 2.5 and 5mg/l for 60 days. Oxidative stress in liver was measured by estimating pro-oxidant and antioxidant activity in liver. Histopathological examination of liver was carried out by light and transmission electron microscopy. Analysis of DNA fragmentation by gel electrophoresis was used to identify apoptosis after the exposure. Terminal deoxy-nucleotidyl transferase mediated dUTP Nick end-labeling (TUNEL) assay was used to qualify and quantify apoptosis. RESULTS: A significant increase in cytochrome-P450 and lipid peroxidation accompanied with a significant alteration in the activity of many of the antioxidants was observed, all suggestive of arsenic induced oxidative stress. Histopathological examination under light and transmission electron microscope suggested a combination of ongoing necrosis and apoptosis. DNA-TUNEL showed an increase in apoptotic cells in liver. Agarose gel electrophoresis of DNA of hepatocytes resulted in a characteristic ladder pattern. CONCLUSION: Chronic arsenic administration induces a specific pattern of apoptosis called post-mitotic apoptosis.",
Arsenic,1519201,"Ubiquitin-conjugating enzyme Cdc34 mediates methylmercury resistance in Saccharomyces cerevisiae by increasing Whi2 degradation Abstract: Overexpression of Cdc34, a ubiquitin-conjugating enzyme, confers methylmercury resistance on yeast cells. This suggests that degradation, by the ubiquitin-proteasome (UP) system, of proteins that enhance methylmercury toxicity might be a factor in the development of methylmercury resistance. The present study shows that yeast cells overexpressing Whi2, a protein that is ubiquitinated in cells, are highly susceptible to methylmercury, suggesting that Whi2 may enhance methylmercury toxicity. Although both Whi2 deficiency and Cdc34 overexpression individually confer methylmercury resistance on yeast cells, Whi2-deficient cells overexpressing Cdc34 showed no additive resistance to methylmercury, compared with Whi2-expressing cells that overexpress Cdc34. The intracellular level of Whi2 was significantly reduced by Cdc34 overexpression; however, this reduction was almost completely attenuated when proteasomal degradation was inhibited. These results suggest that overexpression of Cdc34 confers methylmercury resistance on yeast cells through the UP system by promoting degradation of Whi2, a methylmercury toxicity-enhancing protein.",
Arsenic,1597438,"Changes in geosynthetic clay liner (GCL) properties after 2 years in a cover over arsenic-rich tailings Abstract: A test cover comprised of three different needle-punched geosynthetic clay liner (GCL) products and covered with up to 1 m of cover soil (gravelly sand) was built over arsenic-rich tailings at a former gold mine in Nova Scotia, Canada, to evaluate the performance of the GCLs under local climatic conditions. Of the GCLs examined, one had untreated and two had polymer-enhanced natural sodium bentonite. The three GCLs each had different carriers: one with a woven geotextile, one with a scrim-reinforced nonwoven geotextile, and one with a woven geotextile laminated with a polypropylene film. At some locations, each type of GCL was placed in direct contact with the tailings. At other locations, each GCL was separated from the tailings by 0.15 m of cover soil. Samples of each GCL, tailings, and cover soil were recovered 1 and 2 years after construction. Tests show that the GCL with untreated bentonite maintained a low hydraulic conductivity (?5 × 10?11 m/s) at locations where there was ?0.7 m of cover soil above the GCL even though there was significant cation exchange of the sodium in the GCL with divalent cations in the tailings-soil porewater (the mole fraction of sodium (exchangeable sodium percentage (ESP)) decreased from 65% to 10%–17%). The GCL with polymer-enhanced bentonite had a lower hydraulic conductivity (?3 × 10?11 m/s under ?0.7 m of cover soil above the GCL) and experienced less cation exchange (ESP decreased to 19%–28%) than the standard GCL. The other GCL with polymer-enhanced bentonite and a carrier geotextile coated with a geofilm demonstrated the best hydraulic performance regardless of the thickness of cover soil or presence of an initially uncontaminated foundation layer. The presence of a foundation layer between the GCL and tailings impeded the migration of arsenic from the tailings into the GCLs. All GCLs were serving as an effective barrier to arsenic migration.",
Arsenic,627328,"Risk assessment of arsenic-induced internal cancer at long-term low dose exposure Abstract: Previous epidemiological studies have indicated that ingested inorganic arsenic is strongly associated with a wide spectrum of internal cancers. Little is conducted, however, to assess health effects at long-term low dose exposures by linking biologically based mechanistic models and arsenic epidemiological data. We present an integrated approach by linking the Weibull dose-response function and a physiologically based pharmacokinetic (PBPK) model to estimate reference arsenic guideline. The proposed epidemiological data are based on an 8 years follow-up study of 10,138 residents in arseniasis-endemic areas in southwestern and northeastern Taiwan. The 0.01% and 1% excess lifetime cancer risk based point-of-departure analysis were adopted to quantify the internal cancer risks from arsenic in drinking water. Positive relationships between arsenic exposures and cumulative incidence ratios of bladder, lung, and urinary-related cancers were found using Weibull dose-response model r(2)=0.58-0.89). The result shows that the reference arsenic guideline is recommended to be 3.4 microg L(-1) based on male bladder cancer with an excess risk of 10(-4) for a 75-year lifetime exposure. The likelihood of reference arsenic guideline and excess lifetime cancer risk estimates range from 1.9-10.2 microg L(-1) and 2.84 x 10(-5) to 1.96 x 10(-4), respectively, based on the drinking water uptake rates of 1.08-6.52 L d(-1). This study implicates that the Weibull model-based arsenic epidemiological and the PBPK framework can provide a scientific basis to quantify internal cancer risks from arsenic in drinking water and to further recommend the reference drinking water arsenic guideline.",
Arsenic,1797855,"Coexistence of adsorption and coagulation processes of both arsenate and NOM from contaminated groundwater by nanocrystallined Mg/Al layered double hydroxides Abstract: In this study, nanocrystallined Mg/Al layered double hydroxides (LDH-CO3) and chloridion intercalated nanocrystallined Mg/Al LDHs (LDH-Cl) were synthesized and used for simultaneous removal of arsenic and natural organic matter (NOM) from contaminated groundwater. Humic acid (HA) was selected as a model compound of NOM. The maximum adsorption capacities of arsenate (As(V)) on LDH-CO3 and LDH-Cl are 44.66 and 88.30 mg/g, respectively, and those of HA on LDH-CO3 and LDH-Cl are 53.16 and 269.24 mg/g, respectively. It was found that more than 98% of arsenic and 94% of NOM were eliminated by LDH-Cl from both arsenic and NOM-rich groundwater, which is used as drinking water in Togtoh County, Inner Mongolia, China. The arsenic concentration declined from 231 to 4 ?g/L, which meets the drinking water standard. The adsorption mechanisms were determined by using X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and extended X-ray absorption fine structure spectroscopy techniques (EXAFS). The results showed that the removal of HA was mainly via surface complexation as well as coagulation at the surface of LDHs, while the adsorption of As(V) was mainly via ion-exchange process. The presence of HA exhibited little inhibiting effect on As(V) adsorption by occupying partial binding sites on LDH surfaces. Nevertheless, it could not affect the ion-exchange process of As(V) with the interlayer anions of LDHs. The removal of As(V) and HA can be carried out independently due to the different adsorption mechanisms. By integrating the experimental results, it is clear that LDH-Cl can be potentially used as a cost-effective material for the purification of both arsenic and NOM contaminated groundwater.",
Arsenic,1027487,Arsenic in chronic scabies Abstract: ,
Arsenic,498783,"Biomarkers study for sediment quality assessment in Spanish ports using the crab Carcinus maenas and the clam Ruditapes philippinarum Abstract: Intermolt crab Carcinus maenas and clam Ruditapes philippinarum were used to determine the toxicity of sediments collected in four Spanish ports (Cadiz, Huelva, Pasajes, and Bilbao) under laboratory conditions during 28 days. Sediment samples were analyzed to determine chemical concentration of metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn), polyaromatic hydrocarbons, polychlorinated biphenyls, grain size distribution, and organic matter content. Different biomarkers of exposure of early biological stress were determined after 28-day exposure in crabs and clams, in the hepatopancreas and in the digestive gland, respectively: metallothionein, ethoxyresorufin O-deethylase (EROD), glutathione peroxidase (GPX), glutathione S-transferase (GST), and glutathione reductase activities (GR). The battery of biomarkers tested resulted in showing and linking the bioavailability of various contaminants and sediment characteristics to the toxicity of the different sediments. Significant induction of MTs was observed when organisms were exposed to metal-contaminated sediments (port of Huelva), and induction of EROD and GPX activities after exposure to sediments containing organic compounds (port of Bilbao and Pasajes). Higher induction was shown in biomarkers tested in crabs; nevertheless, only interspecies significant differences were observed in the induction of GR and GST activities. The present work confirms the necessity of using species with different ecological lifestyles for sediment toxicity assessment and validates the use of this set of biomarkers as a potential tool in sediment toxicity assessment.",
Arsenic,1936210,"Ballistic InAs nanowire transistors Abstract: Ballistic transport of electrons at room temperature in top-gated InAs nanowire (NW) transistors is experimentally observed and theoretically examined. From length dependent studies, the low-field mean free path is directly extracted as ~150 nm. The mean free path is found to be independent of temperature due to the dominant role of surface roughness scattering. The mean free path was also theoretically assessed by a method that combines Fermi's golden rule and a numerical Schrödinger-Poisson simulation to determine the surface scattering potential with the theoretical calculations being consistent with experiments. Near ballistic transport (~80% of the ballistic limit) is demonstrated experimentally for transistors with a channel length of ~60 nm, owing to the long mean free path of electrons in InAs NWs.",
Arsenic,1597323,"Recruitment of Normal Stem Cells to an Oncogenic Phenotype by Noncontiguous Carcinogen-Transformed Epithelia Depends on the Transforming Carcinogen Abstract: BACKGROUND: Cancer stem cells (CSCs) drive tumor initiation, progression and metastasis. Microenvironment is critical to the fate of CSCs. We have found that a normal stem cell (NSC) line from human prostate (WPE-stem) is recruited into CSC-like cells by nearby, but noncontiguous arsenic-transformed isogenic malignant epithelial cells (MECs). OBJECTIVE: It is unknown if this recruitment of NSCs into CSCs by non-contact co-culture is specific to arsenic-transformed MECs. Thus, here, we tested the effects of neighboring noncontiguous cadmium-transformed MECs (Cd-MECs) and N-methyl-N-nitrosourea-transformed MECs (MNU-MECs) co-culture on NSCs. RESULTS: After two weeks of non-contact Cd-MEC co-culture, NSCs showed elevated metalloproteinase-9 (MMP-9) and MMP-2 secretion, increased invasiveness, increased colony formation, decreased PTEN expression and formation of aggressive, highly branched ductal-like structures from single cells in Matrigel, all characteristics typical of cancer cells. These oncogenic characteristics did not occur if NSCs were co-cultured with MNU-MECs. The NSCs co-cultured with Cd-MECs retained self-renewal capacity as evidenced by multiple passages (&gt;3) of structures formed in Matrigel. Cd-MEC co-cultured NSCs also showed molecular (increased VIMENTIN, SNAIL1 and TWIST1 expression; decreased E-CADHERIN expression) and morphologic evidence of epithelial-to-mesenchymal transition typical for conversion to CSCs. Dysregulated expression of SC-renewal genes, including ABCG2, OCT-4 and WNT-3, also occurred in NSCs during oncogenic transformation induced by non-contact co-culture with Cd-MECs. CONCLUSIONS: These data indicate that Cd-MECs can recruit nearby NSCs into a CSC-like phenotype, but MNU-MECs do not. Thus, the recruitment of NSCs into CSCs by nearby MECs is dependent on the carcinogen originally used to malignantly transform the MECs.",
Arsenic,1327156,"Cytotoxicity and Proliferation Studies with Arsenic in Established Human Cell Lines: Keratinocytes, Melanocytes, Dendritic Cells, Dermal Fibroblasts, Microvascular Endothelial Cells, Monocytes and T-Cells Abstract: ",
Arsenic,1337526,"The Pnicogen Bond: Its Relation to Hydrogen, Halogen, and Other Noncovalent Bonds Abstract: Among a wide range of noncovalent interactions, hydrogen (H) bonds are well known for their specific roles in various chemical and biological phenomena. When describing conventional hydrogen bonding, researchers use the notation AH···D (where A refers to the electron acceptor and D to the donor). However, the AH molecule engaged in a AH···D H-bond can also be pivoted around by roughly 180°, resulting in a HA···D arrangement. Even without the H atom in a bridging position, this arrangement can be attractive, as explained in this Account. The electron density donated by D transfers into a AH ?* antibonding orbital in either case: the lobe of the ?* orbital near the H atom in the H-bonding AH···D geometry, or the lobe proximate to the A atom in the HA···D case. A favorable electrostatic interaction energy between the two molecules supplements this charge transfer. When A belongs to the pnictide family of elements, which include phosphorus, arsenic, antimony, and bismuth, this type of interaction is called a pnicogen bond. This bonding interaction is somewhat analogous to the chalcogen and halogen bonds that arise when A is an element in group 16 or 17, respectively, of the periodic table. Electronegative substitutions, such as a F for a H atom opposite the electron donor atom, strengthen the pnicogen bond. For example, the binding energy in FH(2)P···NH(3) greatly exceeds that of the paradigmatic H-bonding water dimer. Surprisingly, di- or tri-halogenation does not produce any additional stabilization, in marked contrast to H-bonds. Chalcogen and halogen bonds show similar strength to the pnicogen bond for a given electron-withdrawing substituent. This insensitivity to the electron-acceptor atom distinguishes these interactions from H-bonds, in which energy depends strongly upon the identity of the proton-donor atom. As with H-bonds, pnicogen bonds can extract electron density from the lone pairs of atoms on the partner molecule, such as N, O, and S. The ? systems of carbon chains can donate electron density in pnicogen bonds. Indeed, the strength of A···? pnicogen bonds exceeds that of H-bonds even when using strong proton donors such as water with the same ? system. H-bonds typically have a high propensity for a linear AH···D arrangement, but pnicogen bonds show an even greater degree of anisotropy. Distortions of pnicogen bonds away from their preferred geometry cause a more rapid loss of stability than in H-bonds. Although often observed in dimers in the gas phase, pnicogen bonds also serve as the glue in larger aggregates, and researchers have found them in a number of diffraction studies of crystals.",
Arsenic,1025437,"Monomethylarsonous acid destroys a tetrathiolate zinc finger much more efficiently than inorganic arsenite: Mechanistic considerations and consequences for DNA repair inhibition Abstract: Arsenic compounds are human carcinogens. The ingested inorganic arsenic is metabolized to methylated derivatives, which are considered to be more toxic than the inorganic species. Interactions of trivalent arsenicals with thiol groups of proteins are believed to be important for arsenic carcinogenesis, but inorganic arsenite appears to bind to thiol groups more strongly than the methylated As (III) species. Inhibition of the nucleotide excision repair pathway of DNA repair (NER) is likely to be of primary importance in arsenic carcinogenesis. Previously, we demonstrated that methylated As (III) compounds are more efficient than arsenite in releasing zinc from ZnXPAzf, the zinc finger of XPA, a crucial member of the NER complex [Schwerdtle, T., Walter, I., and Hartwig, A. (2003) Arsenite and its biomethylated metabolites interfere with the formation and repair of stable BPDE-induced DNA adducts in human cells and impair XPAzf and Fpg. DNA Repair (Amsterdam) 2, 1449-1463]. In this work, we used ESI-MS to compare aerobic reactivities of arsenite and monomethylarsonous acid (MMA (III)) toward ZnXPAzf on the molecular level. We demonstrated that equimolar MMA (III) released Zn (II) from ZnXPAzf easily, forming mono- and diarsenical derivatives of XPAzf. This reaction was accompanied by oxidation of unprotected thiol groups of the monomethylarsinated peptide to intramolecular disulfides. The estimated affinity of MMA (III) to XPAzf is 30-fold higher than that established previously for arsenite binding to the thiol groups. No binding of arsenite to the thiol groups of XPAzf was observed under our experimental conditions, and a 10-fold excess of arsenite was required to partially oxidize ZnXPAzf. These results indicate a particular susceptibility of tetrathiolate zinc fingers to MMA (III), thereby providing a novel molecular pathway in arsenic carcinogenesis.",
Arsenic,8633,"Concentration and chemical status of arsenic in the blood of pregnant hamsters during critical embryogenesis: 1 subchronic exposure to arsenate utilizing constant rate administration Abstract: We have determined the concentration, availability, and chemical status of radiolabeled arsenic in the blood of pregnant hamsters at the beginning (morning of Day 8) and the end (morning of Day 9) of the critical period of embryogenesis. Hamster dams were exposed to teratogenic doses of arsenate by means of osmotic minipumps implanted on the morning of Day 6 of the gestation period. Whole blood arsenic concentrations were the same for 48 and 72 hr postimplant. The arsenic concentration of plasma equaled that of red cells. Plasma arsenic was not bound to macromolecules and had the same chemical status 48 and 72 hr postimplant. Arsenate was the dominant form (67% of the total). However, the presence of dimethylarsinic acid and arsenite indicates that the pentavalent species was metabolized. Red cell arsenic was bound to macromolecules in the cell sap. Seventy percent of red cell sap arsenic was dialyzable 48 hr postimplant, but only 56% 72 hr postimplant. Arsenate was the dominant dialyzable red cell species on Day 8 and arsenite was the major dialyzable form on Day 9. Our findings demonstrate a relationship between the maternal blood concentration and chemical status of arsenic and the presence of malformations resulting from a constant rate exposure of pregnant hamsters to arsenate via the osmotic minipump.",
Arsenic,627424,"Global gene expression associated with hepatocarcinogenesis in adult male mice induced by in utero arsenic exposure Abstract: Our previous work has shown that exposure to inorganic arsenic in utero produces hepatocellular carcinoma (HCC) in adult male mice. To explore further the molecular mechanisms of transplacental arsenic hepatocarcinogenesis, we conducted a second arsenic transplacental carcinogenesis study and used a genomewide microarray to profile arsenic-induced aberrant gene expression more extensively. Briefly, pregnant C3H mice were given drinking water containing 85 ppm arsenic as sodium arsenite or unaltered water from days 8 to 18 of gestation. The incidence of HCC in adult male offspring was increased 4-fold and tumor multiplicity 3-fold after transplacental arsenic exposure. Samples of normal liver and liver tumors were taken at autopsy for genomic analysis. Arsenic exposure in utero resulted in significant alterations (p < 0.001) in the expression of 2,010 genes in arsenic-exposed liver samples and in the expression of 2,540 genes in arsenic-induced HCC. Ingenuity Pathway Analysis revealed that significant alterations in gene expression occurred in a number of biological networks, and Myc plays a critical role in one of the primary networks. Real-time reverse transcriptase-polymerase chain reaction and Western blot analysis of selected genes/proteins showed > 90% concordance. Arsenic-altered gene expression included activation of oncogenes and HCC biomarkers, and increased expression of cell proliferation-related genes, stress proteins, and insulin-like growth factors and genes involved in cell-cell communications. Liver feminization was evidenced by increased expression of estrogen-linked genes and altered expression of genes that encode gender-related metabolic enzymes. These novel findings are in agreement with the biology and histology of arsenic-induced HCC, thereby indicating that multiple genetic events are associated with transplacental arsenic hepatocarcinogenesis.",
Arsenic,736197,"Interactions between arsenic-induced toxicity and nutrition in early life Abstract: Exposure to arsenic through drinking water is a major public health problem affecting most countries, although the situation is particularly severe in low-income nations. The health consequences of chronic arsenic exposure include increased risk for various forms of cancer and numerous noncancer effects, including diabetes, skin diseases, chronic cough, and toxic effects on liver, kidney, cardiovascular system, and peripheral and central nervous systems. In recent years increasing reports of effects on fetal and child development have appeared. There seems to be a wide variation in susceptibility to arsenic toxicity, which is likely to be related to factors such as variation in arsenic metabolism, nutrition, host-related defense mechanisms, and genetic predisposition. The main mechanisms of arsenic-nutrition interactions include arsenic-induced oxidative stress, which requires nutrient-dependent defense systems, and arsenic metabolism (methylation) via 1-carbon metabolism, which requires methyl groups, folic acid, vitamin B-12, and betaine for the remethylation of homocysteine to methionine. An efficient first methylation step in combination with a slow second methylation step seems to be most critical from a toxicological point of view. A third mode of arsenic-nutrition interaction involves epigenetic effects and fetal programming via DNA methylation.",
Arsenic,1508680,"Grain yield and arsenic uptake of upland rice inoculated with arbuscular mycorrhizal fungi in As-spiked soils Abstract: A pot trial was conducted to investigate the effects of three arbuscular mycorrhizal (AM) fungi species, including Glomus geosporum BGC HUN02C, G. versiforme BGC GD01B, and G. mosseae BGC GD01A, on grain yield and arsenic (As) uptake of upland rice (Zhonghan 221) in As-spiked soils. Moderate levels of AM colonization (24.1-63.1 %) were recorded in the roots of upland rice, and up to 70 mg kg(-1) As in soils did not seem to inhibit mycorrhizal colonization. Positive mycorrhizal growth effects in grain, husk, straw, and root of the upland rice, especially under high level (70 mg kg(-1)) of As in soils, were apparent. Although the effects varied among species of AM fungi, inoculation of AM fungi apparently enhanced grain yield of upland rice without increasing grain As concentrations in As-spiked soils, indicating that AM fungi could alleviate adverse effects on the upland rice caused by As in soils. The present results also show that mycorrhizal inoculation significantly (p?&lt;?0.05) decreased As concentrations in husk, straw, and root in soils added with 70 mg?kg(-1) As. The present results suggest that AM fungi are able to mitigate the adverse effects with enhancing rice production when growing in As-contaminated soils.",
Arsenic,2278420,"Synthesis and evaluation of 3-acyltetronic acid-containing metal complexing agents Abstract: Potential metal chelators containing one or several acyltetronic acid moieties were prepared from cyclic or acyclic amines and polyamines, and from bis(phenols) by reaction with 1-4 equiv of 3-bromoacetyltetronic acid in the presence of potassium carbonate. The affinity constants of the chelating agents for toxic metallic cations Cd2+, Cs+, and Pb2+ and for dimethylarsinic acid were measured, at pH 7.5 and 9.3. Compound 4, an acyclic triamine containing four acyltetronic moieties, was found to complex efficiently all the tested species. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,2064210,"Effect of particle size of drinking-water treatment residuals on the sorption of arsenic in the presence of competing ions Abstract: Arsenite [As(III)] and arsenate [As(V)] sorption by Fe- and Al-based drinking-water treatment residuals (WTR) was studied as a function of particle size at different pHs, and in the presence of competing ligands, namely, phosphate, citrate, and oxalate. Both WTRs showed high affinity for As oxyanions. However, Al-WTR showed higher As(III) and As(V) sorption capacity than Fe-WTR because of their greater surface area. The effect of particle size on As sorption was pronounced on Fe-WTR, where the smaller fraction sorbed more As(III) and As(V) than the larger fractions, whereas relatively minor effects of particle size on As sorption was observed for Al-WTR. Arsenite sorption on both WTRs increased with increasing pH up to circum-neutral pHs and then decreased at higher pHs, whereas As(V) sorption decreased steadily with increasing pH. The capacity of competing ligands to inhibit sorption was greater for As(III) than As(V) on both WTRs (particularly on Al-WTR) following the sequence: oxalate&lt;citrate&lt;phosphate. It was also a function of As ion residence time on the WTR surfaces: the longer the residence time, the less effective were the competing ligands in As desorption.",
Arsenic,1337531,"Bioconcentration and arsenic speciation analysis in ragworm, Hediste diversicolor (Muller 1776) Abstract: This study focused on bioconcentrations of arsenic in Hediste diversicolor (Müller 1776) after exposure to three different molecule solutions: arsenate, dimethyl-arsinate and arsenobetaine. Speciation analysis was carried out after exposing the organisms to these solutions in order to investigate their arsenic biotransformation capacity. Arsenic reached to the maximum level in these tissues after 15 days' exposure to a solution of 100 ?g L(-1) of arsenobetaine, although a significant increase was obtained in worms exposed to arsenate. Speciation analysis shows that trimethyl-arsine oxide is the slowest detoxification phase recorded in experiment.",
Arsenic,1027522,"Use of biomarkers to show sub-cellular effects in meadow voles (Microtus pennsylvanicus) living on an abandoned gold mine site Abstract: Run-off from mine tailings ponds constitutes the main anthropogenic release of arsenic in Canada. As a potential consequence, wildlife not normally exposed to arsenic under other circumstances may receive toxicologically relevant concentrations of arsenic compounds in their food and water. To test this hypothesis, and to determine if arsenic is being transported through trophic levels, the arsenic concentrations in members of a short food chain (soil-plant-meadow vole) were measured. Arsenic concentrations were higher in exposed organisms compared with those from a reference location. However, elevated concentrations of arsenic do not necessarily indicate impact, and consequently a biomonitoring study was undertaken to determine if there were sub-cellular effects of exposure in meadow voles (Microtus pennsylvanicus) as a consequence of arsenic exposure. In this work, adenosine triphosphate (ATP) and liver glutathione (GSH) levels were used as biomarkers of exposure and the frequency of red blood cell micronuclei (mono- and polychromatic) was used as a biomarker of effect. ATP results were not conclusive but there was a statistically significant relationship between a reduction of GSH in vole livers and increased liver arsenic concentrations. A statistically significant relationship was also observed between increased micronucleated monochromatic red blood cells in voles from arsenic contaminated sites compared to a background location. The results of the GSH and monochromatic red blood cell investigations suggest that there are possible sub-cellular effects on these voles as a consequence of dietary arsenic exposure. This is the first field study in which such effects have been observed in voles living near mine tailings.",
Arsenic,628824,"Monomethylarsonous acid (MMA(III)) is more toxic than arsenite in Chang human hepatocytes Abstract: Methylation has been considered to be the primary detoxication pathway of inorganic arsenic. Inorganic arsenic is methylated by many, but not all animal species, to monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), and dimethylarsinic acid (DMA(V)). The As(V) derivatives have been assumed to produce low toxicity, but the relative toxicity of MMA(III) remains unknown. In vitro toxicities of arsenate, arsenite, MMA(V), MMA(III), and DMA(V) were determined in Chang human hepatocytes. Leakage of lactate dehydrogenase (LDH) and intracellular potassium (K(+)) and mitochondrial metabolism of the tetrazolium salt XTT were used to assess cytotoxicity due to arsenic exposure. The mean LC50 based on LDH assays in phosphate media was 6 microM for MMA(III) and 68 microM for arsenite. Using the assay for K(+) leakage in phosphate media, the mean LC50 was 6.3 microM for MMA(III) and 19.8 microM for arsenite. The mean LC50 based on the XTT assay in phosphate media was 13.6 microM for MMA(III) and 164 microM for arsenite. The results of the three cytotoxicity assays (LDH, K(+), and XTT) reveal the following order of toxicity in Chang human hepatocytes: MMA(III) > arsenite > arsenate > MMA(V) = DMA(V). Data demonstrate that MMA(III), an intermediate in inorganic arsenic methylation, is highly toxic and again raises the question as to whether methylation of inorganic arsenic is a detoxication process. Copyright 2000 Academic Press.",
Arsenic,1339288,"Arsenic exposure through drinking water increases the risk of liver and cardiovascular diseases in the population of West Bengal, India Abstract: <strong>BACKGROUND: </strong>Arsenic is a natural drinking water contaminant affecting 26 million people in West Bengal, India. Chronic arsenic exposure causes cancer, cardiovascular disease, liver disease, neuropathies and ocular diseases. The aims of the present study were to assess bioindicators of hepatocellular injury as indicated by the levels of liver enzymes, to determine the auto immune status, as indicated by the amounts of anti-nuclear antibodies (ANA) and anti-dsDNA antibodies in their serum, and to predict cardiovascular risk in the arsenic exposed population.<br /><br /><strong>METHODS: </strong>Effect of chronic arsenic exposure on liver was determined by liver function tests. Autoimmune status was measured by measuring ANA and anti-dsDNA in serum. Inflammatory cytokines associated with increased cardiovascular disease risk, IL6, IL8 and MCP-1 were determined.<br /><br /><strong>RESULTS: </strong>Our results indicated that serum levels of bilirubin, alanine transaminase, aspartate transaminase, alkaline phosphatase and ANA were increased in the arsenic exposed population. Serum levels of IL6 and IL8 also increased in the arsenic exposed group.<br /><br /><strong>CONCLUSIONS: </strong>Chronic arsenic exposure causes liver injury, increases the serum levels of autoimmune markers and imparts increased cardiovascular risk.",
Arsenic,1018034,"Blood selenium, glutathione peroxidase activity and antioxidant supplementation of subjects exposed to arsenic via drinking water Abstract: This work investigated serum selenium (Se) and glutathione peroxidase (GPx) levels in 25 Croatian subjects exposed to high levels of As from drinking water (median As level in urine: 620.74?g/g creatinine) and 25 controls (32.98?g/g creatinine). The exposed group had lower (p&lt;0.001) median serum Se and GPx levels (Se: 82.34?g/l vs 59.02?g/l; GPx: 45.99U/g hemoglobin vs 38.38U/g hemoglobin). A subsample of 20 exposed subjects took part in a 2-month antioxidant supplementation trial which increased median GPx activity from 30.71 to 40.98U/g hemoglobin (p=0.041) and reduced total urinary As median from 680.15 to 501.96?g/g creatinine (p=0.051). The effect of selected catalase (-262C&gt;T) and GPx1 (-593C&gt;T) gene polymorphisms was also examined. The low Se status and GPx activity may heighten risk of adverse health effects, especially in genetically predisposed individuals. The outcome of antioxidant treatment indicates modulation of As metabolism and oxidative stress, relevance of which needs further research.",
Arsenic,1342414,"Comparative study of hypocholesterolemic and hypolipidemic effects of conjugated linolenic acid isomers against induced biochemical perturbations and aberration in erythrocyte membrane fluidity Abstract: <strong>AIM OF STUDY: </strong>The purpose of the study was to evaluate hypolipidemic and hypocholesterolemic activities of conjugated linolenic acid (CLnA) isomers, present in bitter gourd and snake gourd seed, in terms of amelioration of plasma lipid profile, lipoprotein oxidation and erythrocyte membrane fluidity after oral administration.<br /><br /><strong>METHODS: </strong>Male albino rats were divided into six groups. Group 1 was control, and others were induced with oxidative stress by oral gavage of sodium arsenite (Sa). Group 2 was kept as treated control, and groups 3-6 were further treated with different oral doses of seed oils to maintaining definite concentration of CLnA isomers (0.5 and 1.0% of total lipid for each CLnA isomer).<br /><br /><strong>RESULTS: </strong>CLnA isomers normalized cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride contents in plasma and body weight of experimental rats and decreased cholesterol synthesis by reducing hepatic HMG-CoA reductase activity. Administration of Sa caused alteration in erythrocyte membrane fluidity due to increase in cholesterol and decrease in phospholipid content. Tissue cholesterol and lipid contents were also increased by Sa administration. These altered parameters were reversed by experimental oil administration. Protective effect of CLnA isomers on erythrocyte morphology was observed by atomic force microscopy (AFM). Fatty acid composition of erythrocyte membrane showed decrease in polyunsaturated fatty acid (PUFA) and increase in arachidonic acid content after Sa administration, which was normalized with the treatment of these oils. Supplementation of CLnA isomers restored erythrocyte membrane (EM) lipid peroxidation and lipoprotein oxidation.<br /><br /><strong>CONCLUSION: </strong>CLnA isomers, present in vegetable oils, showed potent hypolipidemic and hypocholesterolemic activities against biochemical perturbations.",
Arsenic,1352465,MUTAGENIC EFFECT OF SODIUM ARSENITE IN CHINESE-HAMSTER CELL LINE DEDE Abstract: ,
Arsenic,1025568,"Experimental investigation of the role of endothelin-1 in idiopathic portal hypertension Abstract: <strong>BACKGROUND AND AIM: </strong>The authors' previous report revealed that endothelin-1 might be released from B lymphocytes in cirrhotic patients with hypersplenism. Other investigators have shown that persistent exposure to environmental contaminants including arsenic might induce idiopathic portal hypertension. The aim of this study was to experimentally identify how endothelin-1 is involved in the development of idiopathic portal hypertension and which cells produce endothelin-1 in the spleen.<br /><br /><strong>METHODS: </strong>Portal pressure and venous endothelin-1 concentrations were measured in rats that were given sodium arsenate orally for long periods, and endothelin-1 expression levels in the spleen were assessed by staining. In a second experiment, B and T lymphocytes and monocyte-derived macrophages cultured from healthy human peripheral blood were stimulated with sodium arsenite, sodium arsenate, lipopolysaccharide and interferon-gamma. Endothelin-1 concentrations in the supernatants were measured by ELISA.<br /><br /><strong>RESULTS: </strong>Arsenic exposure gradually increased portal pressure and venous endothelin-1 levels in rats. Endothelin-1 concentration in the supernatant did not change in every cell type stimulated with arsenic, but it increased in B lymphocytes and monocyte-derived macrophages treated with lipopolysaccharide and interferon-gamma.<br /><br /><strong>CONCLUSIONS: </strong>The in vivo study indicated that arsenic might elevate portal pressure through mechanisms involving endothelin-1. In the in vitro study, lipopolysaccharide and interferon-gamma clearly induced endothelin-1 synthesis not only in monocyte-derived macrophages but also in B lymphocytes, although arsenic treatment did not affect those cells. This study partially supports the hypothesis that idiopathic portal hypertension might be promoted by endothelin-1 overproduction from splenic B lymphocytes in response to certain substances.",
Arsenic,1255508,"Accumulation of arsenic by aquatic plants in large-scale field conditions: Opportunities for phytoremediation and bioindication Abstract: This work focuses on the potential of aquatic plants for bioindication and/or phytofiltration of arsenic from contaminated water. More than 71 species of aquatic plants were collected at 200 sampling points in running waters. The results for the 18 most representative plant species are presented here. The species Ranunculus trichophyllus, Ranunculus peltatus subsp. saniculifolius, Lemna minor, Azolla caroliniana and the leaves of Juncus effusus showed a very highly significant (P&lt;0.001) positive correlation with the presence of arsenic in the water. These species may serve as arsenic indicators. The highest concentration of arsenic was found in Callitriche lusitanica (2346mg/kg DW), Callitriche brutia (523mg/kg DW), L. minor (430mg/kg DW), A. caroliniana (397mg/kg DW), R. trichophyllus (354mg/kg DW), Callitriche stagnalis (354mg/kg DW) and Fontinalis antipyretica (346mg/kg DW). These results indicate the potential application of these species for phytofiltration of arsenic through constructed treatment wetlands or introduction of these plant species into natural water bodies.",
Arsenic,100863,"Both hypomethylation and hypermethylation of DNA associated with arsenite exposure in cultures of human cells identified by methylation-sensitive arbitrarily-primed PCR Abstract: In a previous study we reported that methylation within the promoter region of p53 was altered in human lung A549 cells exposed to arsenite over a 2-week period in culture. In the present study the methylation status of the 5? control region of the tumor suppressor gene, von Hippel Lindau syndrome (VHL), a gene known to be silenced transcriptionally by CpG methylation was assessed. No changes in DNA methylation in VHL in human kidney UOK cell lines exposed to arsenite were seen after 4 weeks in culture, assessed by simple HpaII digestion followed by PCR amplification. Using methylation-sensitive arbitrarily-primed PCR we identified eight differentially methylated regions of genomic DNA of 300–500 bp from three UOK cell lines and from human lung A549 cells after arsenite exposure in culture. Six fragments were hypermethylated, and two were hypomethylated, relative to untreated controls. Sequence analysis revealed two DNA fragments contained repeat sequences of mammalian-apparent LTR retrotransposons, five contained promoter-like sequences, and 13 CpG islands were identified. Three fragments had 99–100% homology to regions on human chromosomes 6, 9, and 15 but these genes have not yet been identified. Our findings are consistent with a potential role for both hypermethylation and hypomethylation of DNA that coexist after exposure to arsenite. The results, in total, could support the existence of a state of DNA methylation imbalance that could conceivably disrupt appropriate gene expression in arsenite exposed cells.",
Arsenic,62159,"Vasospastic tendency and Raynaud's phenomenon in smelter workers exposed to arsenic Abstract: The long-term drinking of water with a high content of inorganic arsenic can lead to Raynaud's phenomenon, acrocyanosis, and gangrene of the lower legs (&quot;black foot disease&quot;). We have measured the systolic blood pressure in the finger after local cooling in 47 workers from a copper smelter who were habitually exposed to moderate amounts of arsenic dust. The controls were 48 workers not exposed to arsenic. The concentration of inorganic arsenic including its metabolites in urine was determined. We found a difference between As-exposed workers and the controls in the finger systolic pressure at skin temperatures of 10 degrees C and/or 15 degrees C expressed as a percentage of the pressure at 30 degrees C (FSP%), P less than 0.01; and the prevalence of Raynaud's phenomenon, P less than 0.05. A low FSP% was taken to indicate vasospastic tendency. There was a covariation between the duration of exposure to arsenic and the decrease in finger systolic pressure between the measurements at 30 and 10 degrees C (P less than 0.05). The uptake of arsenic at the time of the study probably did not exceed 300 micrograms/day. This was confirmed by estimation of the urinary excretion. The average total arsenic uptake was estimated to be about 4 g over 23 years, which is less than the total uptake of 20 g of arsenic by subjects who developed black foot disease. Increased vasospastic reactivity in the fingers and Raynaud's phenomenon in smelter workers seems to be due to functional alterations in the vessels caused by inhalation of arsenic.",
Arsenic,736670,"Marked increase in bladder and lung cancer mortality in a region of Northern Chile due to arsenic in drinking water Abstract: Studies in Taiwan and Argentina suggest that ingestion of inorganic arsenic from drinking water results in increased risks of internal cancers, particularly bladder and lung cancer. The authors investigated cancer mortality in a population of around 400,000 people in a region of Northern Chile (Region II) exposed to high arsenic levels in drinking water in past years. Arsenic concentrations from 1950 to the present were obtained. Population-weighted average arsenic levels reached 570 microg/liter between 1955 to 1969, and decreased to less than 100 microg/liter by 1980. Standardized mortality ratios (SMRs) were calculated for the years 1989 to 1993. Increased mortality was found for bladder, lung, kidney, and skin cancer. Bladder cancer mortality was markedly elevated (men, SMR = 6.0 (95% confidence interval (CI) 4.8-7.4); women, SMR = 8.2 (95% CI 6.3-10.5)) as was lung cancer mortality (men, SMR = 3.8 (95% CI 3.5-4.1); women, SMR = 3.1 (95% CI 2.7-3.7)). Smoking survey data and mortality rates from chronic obstructive pulmonary disease provided evidence that smoking did not contribute to the increased mortality from these cancers. The findings provide additional evidence that ingestion of inorganic arsenic in drinking water is indeed a cause of bladder and lung cancer. It was estimated that arsenic might account for 7% of all deaths among those aged 30 years and over. If so, the impact of arsenic on the population mortality in Region II of Chile is greater than that reported anywhere to date from environmental exposure to a carcinogen in a major population.",
Arsenic,2337235,"Are rice (Oryza sativa L.) phosphate transporters regulated similarly by phosphate and arsenate? A comprehensive study Abstract: Rice is one of the most important staple foods worldwide, but it often contains inorganic arsenic, which is toxic and gives rise to severe health problems. Rice plants take up arsenate As(V) via the phosphate transport pathways, though it is not known how As(V), as compared to phosphate, modifies the expression of phosphate transporters (PTs). Therefore, the impact of As(V) or phosphate (Pi) on the gene expression of PTs and several Pi signaling regulators was investigated. Rice plants were grown on medium containing different As(V) or Pi concentrations. Growth was evaluated and the expression of tested genes was quantified at different time points, using quantitative RT-PCR (qPCR). The As and P content in plants was determined using inductively coupled plasma mass spectrometry (ICP-MS). As(V) elicited diverse and opposite responses of different PTs in roots and shoots, while Pi triggered a more shallow and uniform transcriptional response in several tested genes. Only a restricted set of genes, including PT2, PT3, PT5 and PT13 and two SPX-MFS family members, was particularly responsive to As(V). Despite some common reactions, the responses of the analyzed genes were predominantly ion-specific. The possible reasons and consequences are discussed.",
Arsenic,1022956,"Overview of international environmental health Abstract: Ultimately, the health and quality of life of all human beings depend upon the environment and ecosystems to which we are directly and indirectly connected. The papers in this special edition address a number of the critical environmental health issues on which U.S. government agencies and their collaborating partners are engaged internationally. The agencies are members of the International Environmental Health Subcommittee, chaired by the U.S. Department of Health and Human Services. The activities described span the range from global policy to country-level field activities. While environmental factors related to infectious disease dominate the global burden of environmentally-related disease, acute and chronic exposures to chemicals are increasingly important public health issues at the local, national, and regional levels; arsenic in drinking water is a good example. Intersectoral action involving governments (at all levels), the private sector, and civil society working together in partnership is absolutely critical to sustainably resolving the problems touched on this overview and meeting the environmental health challenges of the twenty-first century.",
Arsenic,2298690,"Positive regulation of rice RING E3 ligase OsHIR1 in arsenic and cadmium uptakes Abstract: The metalloid arsenic (As) and the heavy metal cadmium (Cd) are ubiquitously found at low concentrations in the earth. High concentrations of these elements in the soil and crops are severely dangerous to human health. We attempted to retrieve the RING E3 ubiquitin ligase gene for regulating As and Cd uptakes via the ubiquitin 26S proteasome system. Semi-quantitative reverse transcription polymerase chain reaction was conducted for a total of 47 Oryza sativa RING finger protein (OsRFP) genes to assess their expression patterns when exposed to As and Cd treatments. We identified one gene Oryza sativa heavy metal induced RING E3 ligase 1 (OsHIR1), which was significantly upregulated with both treatments. A yeast hybrid screen and a bimolecular fluorescence complementation assay showed that OsHIR1 clearly interacts with 5 substrate proteins, including tonoplast intrinsic protein 4;1 (OsTIP4;1) in the plasma membrane. In addition, OsHIR1 strongly degraded the protein level of OsTIP4;1 via the ubiquitin 26S proteasome system. Heterogeneous overexpression of OsHIR1 in Arabidopsis exhibited As- and Cd-insensitive phenotypes and resulted in decreased As and Cd accumulation in the shoots and roots, relative to the control. Herein, we report the novel finding that the OsHIR1 E3 ligase positively regulates OsTIP4;1 related to As and Cd uptakes.",
Arsenic,1371461,COMPARISON OF ARSENIC-INDUCED CELL TRANSFORMATION CYTOTOXICITY MUTATION AND CYTOGENETIC EFFECTS IN SYRIAN HAMSTER EMBRYO CELLS IN CULTURE Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM SODIUM ARSENITE SODIUM ARSENATE CARCINOGENESIS PHARMACODYNAMICS COLONY-FORMING EFFICIENCY GENE MUTATIONS,
Arsenic,1354159,Modified Activated Carbon as Solid Phase Extraction Adsorbent for the Preconcentration and Determination of Trace As(III) in Environmental Samples by Graphite Furnace Atomic Absorption Spectrometry Abstract: ,
Arsenic,1021620,"Concentration- and time-dependent genomic changes in the mouse urinary bladder following exposure to arsenate in drinking water for up to 12 weeks Abstract: Inorganic arsenic (As(i)) is a known human bladder carcinogen. The objective of this study was to examine the concentration dependence of the genomic response to As(i) in the urinary bladders of mice. C57BL/6J mice were exposed for 1 or 12 weeks to arsenate in drinking water at concentrations of 0.5, 2, 10, and 50 mg As/l. Urinary bladders were analyzed using gene expression microarrays. A consistent reversal was observed in the direction of gene expression change: from predominantly decreased expression at 1 week to predominantly increased expression at 12 weeks. These results are consistent with evidence from in vitro studies of an acute adaptive response that is suppressed on longer exposure due to downregulation of Fos. Pathways with the highest enrichment in gene expression changes were associated with epithelial-to-mesenchymal transition, inflammation, and proliferation. Benchmark dose (BMD) analysis determined that the lowest median BMD values for pathways were above 5 mg As/l, despite the fact that pathway enrichment was observed at the 0.5 mg As/l exposure concentration. This disparity may result from the nonmonotonic nature of the concentration-responses for the expression changes of a number of genes, as evidenced by the much fewer gene expression changes at 2 mg As/l compared with lower or higher concentrations. Pathway categories with concentration-related gene expression changes included cellular morphogenesis, inflammation, apoptosis/survival, cell cycle control, and DNA damage response. The results of this study provide evidence of a concentration-dependent transition in the mode of action for the subchronic effects of As(i) in mouse bladder cells in the vicinity of 2 mg As(i)/l.",
Arsenic,1031394,"Presence of arsenic in different types of MTA and white and gray Portland cement Abstract: <strong>OBJECTIVE: </strong>The presence of arsenic in various types of mineral trioxide aggregate (MTA) and Portland cements were evaluated to verify if they comply with the ISO-recommended limit for water-based cements of 2 mg arsenic/kg material.<br /><br /><strong>STUDY DESIGN: </strong>An amount of 5 mL of hydrochloric acid was added to 2 g each of MTA and Portland cement to be analyzed. After 15 minutes, the material was filtered and the volume of supernatant was diluted with reagent-grade water up to 40 mL. Atomic absorption spectrophotometry readings were performed in triplicate.<br /><br /><strong>RESULTS: </strong>The following mean values were obtained: CPM (Egeo, Buenos Aires, Argentina) 11.06 mg/kg; CPM sealer (Egeo) 10.30 mg/kg; MTA-Obtura (Angelus, Londrina, PR, Brazil) 0.39 mg/kg; Experimental MTA: 10.30 mg/kg; White MTA-Angelus (Angelus) 1.03 mg/kg; Gray MTA-Angelus (Angelus) 5.91 mg/kg; ProRoot-MTA (Dentsply/Tulsa Dental Specialties, Tulsa, OK) 5.25 mg/kg; Gray Portland cement (Votorantim Cimentos, Cubatão, SP, Brazil): 34.27 mg/kg; and White Portland cement (Cimento Rio Branco, Rio de Janeiro, RJ, Brazil) 0.52 mg/kg.<br /><br /><strong>CONCLUSION: </strong>All tested materials presented arsenic in their composition. The form of arsenic was not analyzed nor the toxicity of the arsenic found. Only MTA-Obtura, White MTA-Angelus, and White Portland cement presented arsenic levels below the limit set in the ISO 9917-1 standard.",
Arsenic,1015748,"Assessment of the mechanisms of detoxification of chemical compounds and antioxidant enzymes in the digestive gland of mussels, Mytilus galloprovincialis, from Mediterranean coastal sites Abstract: In this study the effects of the main marine pollutants (metals, PAHs, PCBs and DDTs) were assessed in native mussels from the Mediterranean coast of Spain. For this purpose several biomarkers such as benzo[a]pyrene hydroxylase (BPH), DT-diaphorase (DTD), glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPs), glutathione reductase (GR), metallothionein (MT) and lipid peroxidation (LPO) were measured in the digestive gland. Results showed increased LPO levels in mussels which accumulated high loads of organic compounds and arsenic in their tissues. BPH levels correlated to the concentrations of organic compounds in mussel tissues, though the range of BPH response was low in relation to the high gradient of accumulation of organic pollutants. Increased BPH levels, concomitant to low DTD and GST activities, were detected in mussels which presented high levels of organic pollutants in their tissues. This suggests that signs of LPO present in these organisms are related to the imbalance between phase I and phase II biotransformation processes. Furthermore, the increased levels of MT and CAT detected in mussels which showed high levels of Cd in their tissues appear to reflect a coordinated response which protects against the toxicity of this metal. The application of these biomarkers in environmental assessment is discussed.",
Arsenic,2347722,"Relative Abundance of Ammonia Oxidizers, Denitrifiers, and Anammox Bacteria in Sediments of Hyper-Nutrified Estuarine Tidal Flats and in Relation to Environmental Conditions Abstract: The relative abundances of nitrifying, denitrifying and anammox prokaryotes in sediments of three hyper-nutrified estuarine tidal flats of Laizhou Bay, Bohai Sea, China were investigated. Quantitative PCR estimates indicated that in most cases archaeal (AOA) amoA genes were more abundant than bacterial (AOB) amoA genes, and ratio of AOA/AOB was correlated with pH, Cd, and Cu. Of the denitrifiers, nirK-type outnumbered nirS-type, with nosZ-type being the lowest. Variation of the ratio between nirK and nirS abundance depends on pH, nitrite, nitrate, and Cd. The combination of (nirS_nirK-nosZ), an indicator of genetic potentials for N2O emission, was only related to the temperature. Anammox bacterial 16S rRNA gene abundances were correlated with salinity, pH, nitrite, and Cu. In contrast, the contribution of anammox to N-2 production, by using anammox bacterial 16S rRNA/nosZ ratio as a proxy, was correlated to temperature, ammonium and dissolved oxygen in the overlying water, ratio of organic carbon to nitrogen, and arsenic in sediments. Our study stresses that abundances of N-cycling functional groups respond differently to variations of environmental conditions, and multiple factors including heavy metals with relatively low concentrations may play a role in shaping nitrogen cycling processes in these estuarine tidal flats.",
Arsenic,1017688,"Arsenic speciation in Japanese rice drinks and condiments Abstract: Rice has been demonstrated to be one of the major contributors to inorganic arsenic (i-As) intake in humans. However, little is known about rice products as additional source of i-As exposure. In this study, misos, syrups and amazake (a fermented sweet rice drink) produced from rice, barley and millet were analysed for total arsenic (t-As) and a subset of samples were also analyzed for As speciation. Rice based products displayed a higher i-As content than those derived from barley and millet. Most of the t-As in the rice products studied was inorganic (63-83%), the remainder being dimethylarsinic acid. Those who regularly consume rice drinks and condiments, such as the Japanese population and those who follow health conscious diets based on the Japanese cuisine, could reach up to 23% of the World Health Organization's Provisional Tolerable Daily Intake of i-As, by only consuming these kinds of products. This study provides a wide appreciation of how i-As derived from rice based products enters the human diet and how this may be of concern to populations who are already exposed to high levels of i-As through consumption of foods such as rice and seaweed.",
Arsenic,1348494,"Expression of hsp 27, hsp 60, hsc 70, and hsp 70 by immortalized human proximal tubule cells (HK-2) following exposure to heat shock, sodium arsenite, or cadmium chloride Abstract: The expression of hsp 27, hsp 60, hsc 70, and hsp 70 mRNA and protein was determined in immortalized human proximal tubule cells (HK-2) exposed to heat shock, sodium arsenite, or cadmium chloride (CdCl2) under both acute and extended conditions of exposure. It was demonstrated that the HK-2 cells did not exhibit the classic heat-shock response when subjected to an acute physical (heat) or chemical stress (sodium arsenite or CdCl2). Heat stress, elevated temperature at 42.5 degrees C for 1 h, caused a marked increase only in hsp 70 mRNA and protein, but not hsp 27 or hsp 60 mRNA and protein. Similar results were obtained when the cells were subjected to a classic chemical stress of exposure to 100 microM sodium arsenite for 4 h or CdCl2 for 4 h. These findings were in contrast to those found previously with mortal human proximal tubule (HPT) cells, where acute stress by all three stimuli elicited marked increases in hsp 27, hsp 60, and hsp 70 mRNA and protein. It was shown that the basal levels of expression of hsp 27 and hsp 60 in the HK-2 cells were elevated when compared to those found in unstressed HPT cells and that the basal levels were similar to those found in HPT cells under stress conditions. These results suggest that the failure of the HK-2 cells to increase hsp 27 and hsp 60 levels in response to physical and chemical stress is because they already possess elevated basal levels of these proteins. This would indicate that one or more of the genetic events that resulted in the immortalization of the HK-2 cells also elicited a stress response for hsp 27 and hsp 60, but not for hsp 70, stress response family members. Overall, the results suggest that although there are differences in the regulation of the stress response between the immortal HK-2 and mortal HPT cell lines, as long as these differences are recognized, the HK-2 cell line should be a valuable adjunct to study the stress response of the proximal tubule in general and when exposed to environmental pollutants such as cadmium.",
Arsenic,2088479,"Chronic exposure to arsenic in drinking water can lead to resistance to antimonial drugs in a mouse model of visceral leishmaniasis Abstract: The Indian subcontinent is the only region where arsenic contamination of drinking water coexists with widespread resistance to antimonial drugs that are used to treat the parasitic disease visceral leishmaniasis. We have previously proposed that selection for parasite resistance within visceral leishmaniasis patients who have been exposed to trivalent arsenic results in cross-resistance to the related metalloid antimony, present in the pentavalent state as a complex in drugs such as sodium stibogluconate (Pentostam) and meglumine antimonate (Glucantime). To test this hypothesis, Leishmania donovani was serially passaged in mice exposed to arsenic in drinking water at environmentally relevant levels (10 or 100 ppm). Arsenic accumulation in organs and other tissues was proportional to the level of exposure and similar to that previously reported in human liver biopsies. After five monthly passages in mice exposed to arsenic, isolated parasites were found to be completely refractory to 500 ?g?mL(-1) Pentostam compared with the control passage group (38.5 ?g?mL(-1)) cultured in vitro in mouse peritoneal macrophages. Reassessment of resistant parasites following further passage for 4 mo in mice without arsenic exposure showed that resistance was stable. Treatment of infected mice with Pentostam confirmed that resistance observed in vitro also occurred in vivo. We conclude that arsenic contamination may have played a significant role in the development of Leishmania antimonial resistance in Bihar because inadequate treatment with antimonial drugs is not exclusive to India, whereas widespread antimonial resistance is.",
Arsenic,1519092,"Direct band gap wurtzite gallium phosphide nanowires Abstract: The main challenge for light-emitting diodes is to increase the efficiency in the green part of the spectrum. Gallium phosphide (GaP) with the normal cubic crystal structure has an indirect band gap, which severely limits the green emission efficiency. Band structure calculations have predicted a direct band gap for wurtzite GaP. Here, we report the fabrication of GaP nanowires with pure hexagonal crystal structure and demonstrate the direct nature of the band gap. We observe strong photoluminescence at a wavelength of 594 nm with short lifetime, typical for a direct band gap. Furthermore, by incorporation of aluminum or arsenic in the GaP nanowires, the emitted wavelength is tuned across an important range of the visible light spectrum (555-690 nm). This approach of crystal structure engineering enables new pathways to tailor materials properties enhancing the functionality.",
Arsenic,1017524,"Creatinine, diet, micronutrients, and arsenic methylation in West Bengal, India Abstract: <strong>BACKGROUND: </strong>Ingested inorganic arsenic (InAs) is methylated to monomethylated (MMA) and dimethylated metabolites (DMA). Methylation may have an important role in arsenic toxicity, because the monomethylated trivalent metabolite [MMA(III)] is highly toxic.<br /><br /><strong>OBJECTIVES: </strong>We assessed the relationship of creatinine and nutrition--using dietary intake and blood concentrations of micronutrients--with arsenic metabolism, as reflected in the proportions of InAS, MMA, and DMA in urine, in the first study that incorporated both dietary and micronutrient data.<br /><br /><strong>METHODS: </strong>We studied methylation patterns and nutritional factors in 405 persons who were selected from a cross-sectional survey of 7,638 people in an arsenic-exposed population in West Bengal, India. We assessed associations of urine creatinine and nutritional factors (19 dietary intake variables and 16 blood micronutrients) with arsenic metabolites in urine.<br /><br /><strong>RESULTS: </strong>Urinary creatinine had the strongest relationship with overall arsenic methylation to DMA. Those with the highest urinary creatinine concentrations had 7.2% more arsenic as DMA compared with those with low creatinine (p &lt; 0.001). Animal fat intake had the strongest relationship with MMA% (highest tertile animal fat intake had 2.3% more arsenic as MMA, p &lt; 0.001). Low serum selenium and low folate were also associated with increased MMA%.<br /><br /><strong>CONCLUSIONS: </strong>Urine creatinine concentration was the strongest biological marker of arsenic methylation efficiency, and therefore should not be used to adjust for urine concentration in arsenic studies. The new finding that animal fat intake has a positive relationship with MMA% warrants further assessment in other studies. Increased MMA% was also associated, to a lesser extent, with low serum selenium and folate.",
Arsenic,1034283,"Synergistic modulation of lymphocyte mitogenesis by carcinogenic xenobiotics Abstract: The effects of combinations of xenobiotics upon in vitro lymphocyte mitogenesis was investigated. Bovine lymphocytes were separated from whole blood, and mitogenesis in response to either phytohemagglutinin or concanavalin-A was measured by the uptake of tritiated thymidine, both in the presence and absence of varying combinations and concentrations of sodium-arsenite (7784465), dieldrin (60571), PP-DDT (50293) lindane (58899), carbaryl (63252), 2,4-D (94757), chlordane (57749), and ultraviolet light. Synergy was found to be a frequent occurrence among the random combinations of xenobiotics used. Generally, for any combinations of xenobiotics used, each at an inhibitory concentration, the two acting together were more inhibitory than could be predicted from their independent effects. For combinations where one of the agents was at a stimulatory concentration, while the other was at an inhibitory level, the two together showed either excessive stimulation or depression; the magnitude of the effect was generally not additive. When the concentration of both agents was selected such that each was independently stimulating, the two together showed either excessive stimulation or suppression. The authors conclude that synergy between mitogenic modulators may be commonplace, and that caution should be exercised in proposing permissible levels of metabolically active xenobiotics.",
Arsenic,1024736,"Blood metallothionein transcript as a biomarker for metal sensitivity: Low blood metallothionein transcripts in arsenicosis patients from Guizhou, China Abstract: <strong>BACKGROUND: </strong>Because metallothionein (MT) is a metal-binding protein that protects against metal intoxication, it could be a biomarker for individual sensitivity to metal toxicity.<br /><br /><strong>OBJECTIVE: </strong>We assessed the use of bloodborne MT transcript as a reflection of tissue MT levels and examined the potential role of MT in arsenic toxicity in an environmentally exposed human population.<br /><br /><strong>METHOD: </strong>Rodents were treated with zinc or nonmetallic MT inducers for 4 days, and the blood and tissues were collected for MT transcript analysis by real-time reverse transcriptase-polymerase chain reaction and MT protein determination by the cadmium-hemoglobin assay. Blood and buccal cell samples were collected from arsenicosis patients and healthy subjects residing in Guizhou, China, and total RNA was isolated for MT transcript analysis.<br /><br /><strong>RESULTS: </strong>There was a positive correlation between blood MT-1 and MT-2 transcripts and corresponding hepatic or renal MT transcript levels in rats and mice. Furthermore, there was a positive correlation between blood MT-1 and MT-2 transcript and tissue MT protein levels in these animals. A positive correlation also occurred between human blood MT and buccal cell MT transcript levels. MT-1A and MT-2A were the major isoform transcripts in human blood and buccal cells, and significantly lower MT levels were seen in arsenicosis patients compared with healthy subjects.<br /><br /><strong>CONCLUSIONS: </strong>Blood MT transcript appears to be a useful biomarker of tissue MT levels. Arsenicosis patients in Guizhou show significantly lower MT transcript levels in blood, which may have predisposed this population to arsenic intoxication.",
Arsenic,2337284,"Nasolabial appearance after two palatoplasty types in cleft lip and palate Abstract: BACKGROUND: Facial appearance is important for normal psychosocial development in children with cleft lip and palate (CLP). There is conflicting evidence on how deficient maxillary growth may affect nasolabial esthetics. METHODS: We retrospectively investigated nasolabial appearance in two groups, the Langenback (35 children; mean age 11.1 years; range: 7.9-13.6) and Vomerplasty (58 children; mean age 10.8 years; range: 7.8-14), who received unilateral CLP surgery by the same surgeon. The hard palate repair technique differed between the two groups. In the Langenback group, palatal bone on the non-cleft side only was left denuded, inducing scar formation and inhibiting maxillary growth. In the Vomerplasty group, a vomerplasty with tight closure of the soft tissues on the palate was applied. Thirteen lay judges rated nasolabial esthetics on photographs using a modified Asher-McDade's index. RESULTS: Nasolabial esthetics in both groups was comparable (p > 0.1 for each nasolabial component). Inferior view was judged as the least esthetic component and demonstrated mean scores 3.18 (SD = 0.63) and 3.13 (SD = 0.47) in the Langenback and Vomerplasty groups, respectively. Mean scores for other components were from 2.52 (SD = 0.63) to 2.81 (SD = 0.62). Regression analysis showed that vomerplasty is related with slight improvement in the nasal profile only (coefficient B = -0.287; p = 0.043; R(2) = 0.096). CONCLUSIONS: This study demonstrates that the use of vomerplasty instead of the Langenbeck technique is weakly associated with the nasolabial appearance among pre-adolescent patients with UCLP.",
Arsenic,1597312,"Roxarsone, Inorganic Arsenic, and Other Arsenic Species in Chicken: A U.S.-Based Market Basket Sample Abstract: BACKGROUND: Arsenic-based drugs are permitted in poultry production. Inorganic arsenic (iAs) causes cancer and maybe other adverse health outcomes. The contribution of chicken consumption to iAs intake, however, is unknown. OBJECTIVES: To characterize arsenic species profile in chicken meat and estimate bladder and lung cancer risk associated with consuming chicken produced with arsenic-based drugs. METHODS: Conventional, conventional antibiotic-free, and organic chicken samples were collected from grocery stores in ten US metropolitan areas from December 2010 to June 2011. 116 raw and 142 cooked samples were tested for total arsenic, and 78 samples ?10µg/kg dry weight underwent speciation. RESULTS: Total arsenic geometric mean (GM) in cooked chicken meat samples was 3.0 µg/kg (95% CI: 2.5, 3.6). Among 78 cooked samples that were speciated, iAs concentrations were higher in conventional samples (GM = 1.8 µg/kg; 95% CI: 1.4, 2.3) than antibiotic-free (GM = 0.7 µg/kg; 95% CI: 0.5, 1.0) or organic (GM = 0.6 µg/kg; 95% CI: 0.5, 0.8) samples. Roxarsone was detected in 20 of 40 conventional samples, one of 13 antibiotic-free samples, and none of the 25 organic samples. iAs concentrations in roxarsone-positive samples (GM = 2.3 µg/kg; 95% CI: 1.7, 3.1) were significantly higher than in roxarsone-negative samples (GM = 0.8 µg/kg; 95% CI: 0.7, 1.0). Cooking increased iAs and decreased roxarsone concentrations. Compared to organic chicken consumers, we estimated that conventional chicken consumers would ingest an additional 0.11µg/day iAs (in an 82g serving). Assuming lifetime exposure and a proposed cancer slope factor of 25.7 (mg kgBW-1 day-1)-1, this could result in 3.7 extra lifetime bladder and lung cancer cases per 100,000 exposed-persons. CONCLUSIONS: Conventional chicken meat had higher iAs concentrations than conventional antibiotic-free and organic chicken meat samples. Cessation of arsenical drug use could reduce exposure and the burden of arsenic-related disease in chicken consumers.",
Arsenic,1019552,"Study on the distribution of radioactive trace elements in vitamin D-overloaded rats using the multitracer technique Abstract: The uptake and distribution of radioisotopes of beryllium, calcium, scandium, vanadium, chromium, manganese, iron, cobalt, nickel, zinc, gallium, arsenic, strontium and barium in vitamin D (VD)-overloaded rats were investigated and compared with those in control rats, using the multitracer technique. Each element revealed its characteristic distribution among various organs in control and VD-overloaded rats. For some elements, such as cobalt and chromium, the distribution patterns in them were significantly different. These results are discussed in terms of the metabolism of the elements in rats.",
Arsenic,1327342,"Resveratrol sensitizes melanomas to TRAIL through modulation of antiapoptotic gene expression Abstract: Although many human melanomas express the death receptors TRAIL-R2/DR5 or TRAIL-R1/DR4 on cell surface, they often exhibit resistance to exogenous TRAIL. One of the main contributors to TRAIL-resistance of melanoma cells is upregulation of transcription factors STAT3 and NF-kappaB that control the expression of antiapoptotic genes, including cFLIP and Bcl-xL. On the other hand, the JNK-cJun pathway is involved in the negative regulation of cFLIP (a caspase-8 inhibitor) expression. Our observations indicated that resveratrol, a polyphenolic phytoalexin, decreased STAT3 and NF-kappaB activation, while activating JNK-cJun that finally suppressed expression of cFLIP and Bcl-xL proteins and increased sensitivity to exogenous TRAIL in DR5-positive melanomas. Interestingly, resveratrol did not increase surface expression of DR5 in human melanomas, while gamma-irradiation or sodium arsenite treatment substantially upregulated DR5 expression. Hence, an initial increase in DR5 surface expression (either by gamma-irradiation or arsenite), and subsequent downregulation of antiapoptotic cFLIP and Bcl-xL (by resveratrol), appear to constitute an efficient approach to reactivate apoptotic death pathways in TRAIL-resistant human melanomas. In spite of partial suppression of mitochondrial function and the mitochondrial death pathway, melanoma cells still retain the potential to undergo the DR5-mediated, caspase-8-dependent death pathway that could be accelerated by either an increase in DR5 surface expression or suppression of cFLIP. Taken together, these results suggest that resveratrol, in combination with TRAIL, may have a significant efficacy in the treatment of human melanomas.",
Arsenic,735043,"Epigenetic mediated transcriptional activation of WNT5A participates in arsenical-associated malignant transformation Abstract: Arsenic is a human carcinogen with exposure associated with cancer of the lung, skin, and bladder. Many potential mechanisms have been implicated as playing a role in the process of arsenical-induced malignancy including the perturbation of signaling pathways and aberrant epigenetic regulation. We initiated studies to examine the role of a member of the non-canonical WNT signaling pathway, WNT5A, in UROtsa cells and arsenite [URO-ASSC] and monomethylarsonous acid [URO-MSC] malignantly transformed variants. We present data herein that suggest that WNT5A is transcriptionally activated during arsenical-induced malignant transformation. This WNT5A transcriptional activation is correlated with the enrichment of permissive histone modifications and the reduction of repressive modifications in the WNT5A promoter region. The epigenetic activation of WNT5A expression and acetylation of its promoter remain after the removal of the arsenical, consistent with the maintenance of an anchorage independent growth phenotype in these cells. Additionally, treatment with epigenetic modifying drugs supports a functional role for these epigenetic marks in controlling gene expression. Reduction of WNT5A using lentiviral shRNA greatly attenuated the ability of these cells to grow in an anchorage independent fashion. Extension of our model into human bladder cancer cell lines indicates that each of the cell lines examined also express WNT5A. Taken together, these data suggest that the epigenetic remodeling of the WNT5A promoter is correlated with its transcriptional activation and this upregulation likely participates in arsenical-induced malignant transformation.",
Arsenic,1256734,A biosensor selective for organoarsenicals Abstract: Organoarsenicals used as herbicides and growth promoters for farm animals are degraded to inorganic arsenic. Available bacterial whole-cell biosensors detect only inorganic arsenic. We report a biosensor selective for trivalent organoarsenicals methylarsenite and phenylarsenite over inorganic arsenite. This sensor may useful for detecting degradation of arsenic-containing herbicides and growth promoters.,
Arsenic,1347900,"MODULATION OF THE STRESS-INDUCED SYNTHESIS OF STRESS PROTEINS BY A PHORBOL ESTER AND OKADAIC ACID Abstract: The expression of alphaB crystallin, hsp27, and hsp70 in C6 cells increased when they were exposed to arsenite (50 microM for 1 h) or heat (42 degrees C for 30 min), as detected by specific immunoassays, Western blot analysis, and Northern blot analysis. When cells were exposed to arsenite in the presence of 0.1 microM phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, or 0.2 microM okadaic acid, an inhibitor of phosphoserine/phosphothreonine protein phosphatases, expression of alphaB crystallin was markedly enhanced. The induction of hsp27 and hosp70 expression was also stimulated to a considerable extent in the same cells. The stimulatory effect of PMA was further enhanced in the presence of okadaic acid, but it was strongly inhibited in the presence of 0.5 microM staurosporine, an inhibitor of protein kinase C. PMA and okadaic acid also stimulated the response to heat stress of the expression of alphaB crystallin, but they barely stimulated the response to heat stress of hsp27. The extent of stimulation of the arsenite-induced responses by PMA and okadaic acid was greater when the concentration of arsenite (i.e. the magnitude of the stress) was relatively low (25-50 microM). The arsenite-induced release of arachidonic acid from cells was also stimulated in the presence of PMA and/or akadaic acid, and the stimulatory effects of PMA and okadaic acid on the arsenite-induced accumulation of alphaB crystallin and hsp27 were strongly suppressed by quinacrine, an inhibitor of phospholipase A2. These results suggest that the stimulatory effects of PMA and okadaicacid on the stress responses are cuased, in part, by the increased metabolic activity of the arachidonic acid cascade, as a consequence of the activation of phospholipase A.",
Arsenic,2298737,"Gradient elution moving boundary electrophoresis with field-amplified continuous sample injection Abstract: The integration of simple and robust device components required for the successful adaptation of many analytical methods to multiplexed and field-portable devices often has negative effects on detection sensitivity, such as in the optical detection components in a capillary electrophoresis (CE) system. One of the simplest methods to improve sensitivity in the CE field is known as sample stacking. This method involves preparing the sample in a buffer with a different concentration (and conductivity) than that of the run buffer so that when an electric field is applied the analyte concentration is increased at the boundary between the two different buffer concentrations. Here, we describe a method in which the sample is prepared in a buffer at a lower concentration than the run buffer coupled with a recently described counterflow electrophoresis method, gradient elution moving boundary electrophoresis (GEMBE), with channel current detection. Because of the continuous sample introduction with GEMBE, we refer to the method as field-amplified continuous sample injection (FACSI). This method achieves a significantly greater signal enhancement than expected for sample stacking. For example, we achieve signal enhancement of 110× with a conductivity ratio of 8.21, and using the detection of arsenate in drinking water as a model system, we have achieved a limit of detection (LOD) improvement of approximately 60× (LODs with and without FACSI are 200 nmol/L and 12 ?mol/L, respectively) with a conductivity ratio of approximately 5.93.",
Arsenic,2345793,"The relevance of physicochemical and biological parameters for setting emission limit values for plants treating complex industrial wastewaters Abstract: The influents of plants treating complex industrial wastewaters from third parties may contain a large variety of often unknown or unidentified potentially harmful substances. The conventional approach of assessing and regulating the effluents of these plants is to set emission limit values for a limited set of physicochemical parameters, such as heavy metals, biological oxygen demand, chemical oxygen demand and adsorbable organic halogen compounds. The objective of this study was to evaluate the relevance of physicochemical parameters for setting emission limit values for such plants based on a comparison of effluent analyses by physicochemical and biological assessment tools. The results show that physicochemical parameters alone are not sufficient to evaluate the effectiveness of the water treatment plants for removing hazardous compounds and to protect the environment. The introduction of toxicity limits and limits for the total bioaccumulation potential should be considered to supplement generic parameters such as chemical oxygen demand and adsorbable organic halogens. A recommendation is made to include toxicity screening as a technique to consider in the determination of best available techniques (BAT) during the upcoming revision of the BAT reference document for the waste treatment industries to provide a more rational basis in decisions on additional treatment steps.",
Arsenic,1519221,Trace Elements in Benchmark Soils of Oklahoma Abstract: ,
Arsenic,1936026,"Modelling of arsenic retention in constructed wetlands Abstract: A new model was developed in order to simulate the most significant arsenic retention processes that take place in constructed wetlands (CWs) treating high arsenic waters. The present contribution presents the implementation phases related to plants (arsenic uptake and accumulation, root arsenic adsorption, and root oxygen release), showing the first simulation results of the complete model. Different approaches with diverse influent configurations were simulated. In terms of total arsenic concentrations in effluent, the simulated data closely matched the data measured in all evaluated cases. The iron and arsenic species relationships, and the arsenic retention percentages obtained from simulations, were in agreement with the experimental data and literature. The arsenic retention efficiency increased whenever a new phase was implemented, reaching a maximum efficiency range of 85-95%. According to the quality of the obtained results, it can be considered that the implementation of all steps of RCB-ARSENIC provided reasonably good response values.",
Arsenic,1244032,"Hypertension in chronic arsenic exposure: A case control study in West Bengal Abstract: Various systemic manifestations are reported to be caused by chronic arsenic exposure in the population living in the Indo-Bangladesh subcontinent. This study from West Bengal assesses the likelihood of occurrence of hypertension (HTN) in individuals resident in an area of high groundwater contamination with arsenic (Nadia district) compared to those from a non-contaminated area (Hoogly district) in West Bengal, India. Two hundred and eight study participants (Group 1) were recruited from a cross-sectional study in six villages in the Nadia district and 100 controls (Group 2) from a village in the Hoogly district. The two groups were evenly matched in regard to age and sex. History taking and clinical examination including blood pressure measurement were undertaken in each participant. Water samples from current and previous drinking water sources and hair and urine samples from each participant were collected for estimation of arsenic. The present study shows evidence of increased association of HTN in individuals resident in arsenic endemic region compared to those from a non-endemic region in West Bengal. There were increased odds ratios for HTN [Adjusted Odds Ratio, OR, 2.87 (95 %CI = 1.26-4.83)] in Group- 1 participants compared to Group- 2 people. Within Group 1, there was no difference in prevalence of HTN between those with and without skin lesion. There was a dose-effect relationship seen with increasing cumulative arsenic exposure and arsenic level in hair and HTN in participants living in arsenic endemic region.The findings reported here support an association between arsenic exposure and HTN. More work is needed to characterize the link further.",
Arsenic,710938,"Genetic association between intronic variants in AS3MT and arsenic methylation efficiency is focused on a large linkage disequilibrium cluster in chromosome 10 Abstract: Differences in arsenic metabolism are known to play a role in individual variability in arsenic-induced disease susceptibility. Genetic variants in genes relevant to arsenic metabolism are considered to be partially responsible for the variation in arsenic metabolism. Specifically, variants in arsenic (3+ oxidation state) methyltransferase (AS3MT), the key gene in the metabolism of arsenic, have been associated with increased arsenic methylation efficiency. Of particular interest is the fact that different studies have reported that several of the AS3MT single nucleotide polymorphisms (SNPs) are in strong linkage-disequilibrium (LD), which also extends to a nearby gene, CYP17A1. In an effort to characterize the extent of the region in LD, we genotyped 46 SNPs in a 347,000 base region of chromosome 10 that included AS3MT in arsenic-exposed subjects from Mexico. Pairwise LD analysis showed strong LD for these polymorphisms, represented by a mean r(2) of 0.82, spanning a region that includes five genes. Genetic association analysis with arsenic metabolism confirmed the previously observed association between AS3MT variants, including this large cluster of linked polymorphisms, and arsenic methylation efficiency. The existence of a large genomic region sharing strong LD with polymorphisms associated with arsenic metabolism presents a predicament because the observed phenotype cannot be unequivocally assigned to a single SNP or even a single gene. The results reported here should be carefully considered for future genomic association studies involving AS3MT and arsenic metabolism.",
Arsenic,1677567,"HTLV-1 Tax oncoprotein stimulates ROS production and apoptosis in T-cells by interacting with USP10 Abstract: Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL), and the viral oncoprotein Tax plays key roles in the immortalization of human T-cells, lifelong persistent infection and leukemogenesis. We herein identify the ubiquitin-specific protease 10 (USP10) as a Tax-interactor in HTLV-1-infected T-cells. USP10 is an anti-stress factor against various environmental stresses, including viral infections and oxidative stress. Upon exposure to arsenic, an oxidative stress inducer, USP10 is recruited into stress granules (SGs), and USP10-containing SGs reduce reactive oxygen species (ROS) production and inhibit ROS-dependent apoptosis. We found that interaction of Tax with USP10 inhibits arsenic-induced SG formation, stimulates ROS production and augments ROS-dependent apoptosis in HTLV-1-infected T-cells. These findings suggest that USP10 is a host factor that inhibits stress-induced ROS production and apoptosis in HTLV-1-infected T-cells; however, its activities are attenuated by Tax. A clinical trial showed that combination therapy containing arsenic is effective against some forms of ATL. Therefore, these findings may be relevant to chemotherapy against ATL.",
Arsenic,2149262,"Soil Profile Arsenic Concentration Distributions in Missouri Soils Having Cambic and Argillic Soil Horizons Abstract: Understanding of the pedogenic pathways associated with arsenic (As) transformations in soil is important to understanding arsenic soil chemistry and discriminating between natural background and anthropogenic arsenic (As). Twenty-one soil series, some with multiple pedons, were assessed to determine if the As distributions in soil profiles exhibit discrete maxima that correspond to the presence of agrillic horizons. The majority of pedons exhibiting argillic horizon expression show a Fe-oxyhydroxide and As maxima corresponding precisely with the argillic horizon. Pearson correlation coefficients verify the close correspondence of Fe and As. Soil profiles having cambic horizons, and lacking argillic horizons, may also show As and Fe accumulations at soil depths. Some coarse-textured, well-drained to moderately well-drained Entisols and Inceptisols have Fe-oxyhydroxide accumulation in their cambic horizons, promoting As accumulation. Conversely, silty-textured and poorly drained to somewhat poorly drained Entisols and Inceptisols have C and Cg horizons that show somewhat uniform Fe and As concentrations throughout their soil profiles. Analysis of selected pedons having well-drained to moderately well-drained soil profiles demonstrates that clay fraction Fe and As concentrations are closely correlated and that the As and Fe concentrations are greater than those from the corresponding whole soil. The somewhat poorly drained Crowley pedon exhibited cohesive masses of Fe and Mn accumulation (sand separate) that had greater arsenic concentrations than those of the clay and silt separates. These pedogenic nodules with enhanced arsenic concentrations reveal alternative pathways involving arsenic transformation.",
Arsenic,1020259,"Arsenic and porphyrins Abstract: BACKGROUND: To evaluate the possible effect of inorganic arsenic (iAs) and of its species on the urinary excretion of porphyrin homologues. METHODS: Total porphyrins and their homologues (copro, penta, hexa, hepta, uroporphyrins) and arsenic species (trivalent and pentavalent As; monomethyl arsonic acid; dimethyl arsenic acid; arsenobetaine) were measured respectively by HPLC and HPLC-ICP MS in urine from 86 art glass workers exposed to iAs and from 54 controls. RESULTS: A significant increase in the excretion of penta and uroporphyrins was demonstrated for workers exposed to As; As3 was the species best correlated with urinary porphyrin excretion. CONCLUSIONS: The increase of urinary excretion for some porphyrin homologues appears to be consistent with the inhibition by As of URO-decarboxylase in the heme biosynthesis pathway. The determination of urinary porphyrin homologues could be useful to assess, on a group basis, some early effects of arsenic and to demonstrate possible individual susceptibility to the element.",
Arsenic,1345117,Actinic keratoses in dermatologic diseases Abstract: ,
Arsenic,1015658,"Characterization of the role of protein-cysteine residues in the binding with sodium arsenite Abstract: To better characterize the interaction of protein-cysteines with sodium arsenite, arsenic-binding proteins were identified from the arsenic-resistant Chinese hamster ovary cell line SA7 using a p-aminophenylarsine oxide (PAO)-agarose matrix in combination with proteomic techniques. Twenty of the isolated arsenic-binding proteins were further peptide-mapped by MALDI-Q-TOF-MS. The binding capacity of PAO-agarose-retained proteins was then verified by re-applying Escherichia coli overexpressed recombinant proteins with various numbers of cysteine residues onto the PAO-agarose matrix. The results showed that recombinant heat shock protein 27 (HSP27, with one cysteine residue), reticulocalbin-3 (RCN3, with no cysteine residue), galectin-1 (GAL1, with six cysteine residues), but not peroxiredoxin 6 (Prdx6, with one cysteine residue but not retained by the PAO-agarose matrix), were bound to the PAO-agarose matrix. The six free cysteine residues in GAL1 were individually or double-mutated to alanine by means of site-directed mutagenesis and subjected to CD and ICP-MS analysis. The binding capacity of GAL1 for sodium arsenite was significantly attenuated in C16A, C88A and all double mutant clones. Taken together, our current data suggest that the cysteine residues in GAL1 may play a critical role in the binding of arsenic, but that in the case of RCN3 and Prdx6, this interaction may be mediated by other factors.",
Arsenic,1022024,"Arsenic exposure from drinking water and dyspnoea risk in Araihazar, Bangladesh: A population-based study Abstract: Bangladesh has high well water arsenic exposure. Chronic arsenic ingestion may result in diseases manifest as dyspnoea; albeit information is sparse.Baseline values were obtained from an arsenic study. Trained physicians ascertained data on dyspnoea among 11,746 subjects. Data was collected on demographic factors including smoking, blood pressure and arsenic exposure. Logistic regression models estimated odds ratios and confidence intervals for the association between arsenic exposure and dyspnoea.The adjusted odds of having dyspnoea was 1.32-fold (95% C.I., 1.15-1.52) greater in those exposed to high arsenic well water concentrations (? 50 ?g·L(-1)) as compared to low arsenic exposed nonsmokers (p<0.01). A significant dose-response relationship was found for arsenic (as-well-as smoking) in relation to dyspnoea. In nonsmokers, the adjusted odds of having dyspnoea were 1.36, 1.96, 2.34, and 1.80-fold greater for arsenic concentrations of 7-38, 39-90, 91-178, and 179-864 ug·L(-1), respectively, compared to the referent arsenic concentration of less than 7 ug·L(-1) (p<0.01, Chi square test for trend).Arsenic exposure through well water is associated with dyspnoea independent of smoking status. This study suggests that mandated well water testing for arsenic with reduction in exposure may significantly reduce diseases manifest as dyspnoea, usually cardiac or pulmonary.",
Arsenic,710816,"The arsenic exposure hypothesis for Alzheimer disease Abstract: Prior research has shown that arsenic exposure induces changes that coincide with most of the developmental, biochemical, pathologic, and clinical features of Alzheimer disease (AD) and associated disorders. On the basis of this literature, we propose the Arsenic Exposure Hypothesis for AD that is inclusive of and cooperative with the existing hypotheses. Arsenic toxicity induces hyperphosphorylation of protein tau and overtranscription of the amyloid precursor protein, which are involved in the formation of neurofibrillary tangles and brain amyloid plaques, consistent with the amyloid hypothesis of AD. Arsenic exposure has been associated with cardiovascular diseases and associated risk factors, which is in agreement with the vascular hypothesis of AD. Arsenic exposure invokes brain inflammatory responses, which resonates with the inflammatory hypotheses of AD. Arsenic exposure has been linked to reduced memory and intellectual abilities in children and adolescents, which provides a biologic basis for the developmental origin of health and disease hypothesis for AD. Arsenic and its metabolites generate free radicals causing oxidative stress and neuronal death, which fits the existing oxidative stress hypothesis. Taken together, the arsenic exposure hypothesis for AD provides a parsimonious testable hypothesis for the development and progression of this devastating disease at least for some subsets of individuals.",
Arsenic,710791,"Adverse effects of arsenic exposure on uterine function and structure in female rat Abstract: The present investigation examined the adverse effects of arsenic exposure on uterine function and structure of female rat at 56 days of age, exposed to different doses (50, 100, and 200ppm) of sodium arsenite in drinking water at immature age (28 days) for 28 days. Dose-dependent decrease (P<0.001) was observed in mean uterine weight and length in all treated groups compared to control. Higher arsenic deposition was found in uterine tissue against increased doses of arsenite. Arsenite treatment altered the histomormphology of the uterus. Uterine epithelium in 50ppm group was lined by cuboidal cells instead of columnar cells observed in control epithelium. In 100 and 200ppm groups, no demarcation was observed between epithelial cells and endometrial stroma. No basement membrane was seen in these groups; even in 50ppm, basement membrane was disturbed. The endometrial stroma in 100 and 200ppm groups was very dense in appearance and contained irregular-shaped cells. In myometrium, loosening of cells was observed in 100 and 200ppm groups. Dose-dependent decrease (P<0.001) was observed in mean uterine diameter, epithelial height, thickness of endometrium, myometrium, and in plasma levels of estradiol, progesterone, FSH and LH in all the treatment groups compared to control. In summary, arsenic is a major threat to female reproductive health acting as a reproductive toxicant and as an endocrine disruptor, restricted the function and structure of uterus, by altering the gonadotrophins and steroid levels, not only at high dose concentration but also at low (50ppm) levels, when they become mature.",
Arsenic,1448860,"Contamination by metals and pharmaceuticals in northern Taihu Lake (China) and its relation to integrated biomarker response in fish Abstract: Taihu Lake is the largest shallow freshwater lake in eastern China and is suffering not only from an increasingly serious threat of eutrophication but also potential ecological risk due to the input of emerging contaminants. Active biomonitoring was conducted in Taihu Lake using transplanted goldfish (Carassius auratus) to determine the contamination by pharmaceuticals and metals and to assess the potential ecological risk. A suite of biomarkers including acetylcholinesterase, ethoxyresorufin O-deethylase, glutathione S-transferase, glutathione peroxidase and superoxide dismutase activities in fish after 7, 14, 21 and 28 days of exposure in situ, as well as pharmaceuticals and metals in water, were determined during the field exposure period. The results indicate that pharmaceuticals exist mainly in Zhushan Bay and Meiliang Bay, while metals are present mainly in Gong Bay. An integrated biomarker response (IBR) was calculated and used to evaluate the ecological risk of the polluted area of Taihu Lake. It was found that Zhushan Bay might present higher risk to fish, followed by Meiliang Bay. IBR values were in good agreement with copper and caffeine concentrations.",
Arsenic,539249,"Proteomic profiling in the sera of workers occupationally exposed to arsenic and lead: identification of potential biomarkers Abstract: Arsenic (As) and lead (Pb) are important inorganic toxicants in the environment. Frequently, humans are exposed to the mixtures of As and Pb, but little is known about the expression of biomarkers resulting from such mixed exposures. In this study, we analyzed serum proteomic profiles in a group of smelter workers with the aim of identifying protein biomarkers of mixed As and Pb exposure. Forty-six male workers co-exposed to As and Pb were studied. Forty-five age-matched male office workers were chosen as controls. Urine As and blood Pb concentrations were determined. Serum proteomic profiles were analyzed by Surface-Enhanced Laser Desorption/Ionization Time-Of-Flight (SELDI-TOF) mass spectrometer on the WCX2 ProteinChip. Using Recursive support vector machine (RSVM) algorithm, a panel of five peptides/proteins (2097 Da, 2953 Da, 3941 Da, 5338 Da, and 5639 Da) was selected based on their collective contribution to the optional separation between higher metal mixture exposure and non-exposure controls. Among these five selected markers, the 3941 Da was down-regulated and the four other proteins were up-regulated. Descriptive statistics confirmed that these five proteins differed significantly between metal exposure and non-exposure. Interestingly, the combined use of the five selected biomarkers could achieve higher discriminative power than single marker. These results demonstrated that proteomic technology, in conjunction with bioinformatics tools, could facilitate the discovery of new and better biomarkers of mixed metal exposure.",
Arsenic,2279001,"A 2,4-dichlorophenoxyacetic acid degradation plasmid pM7012 discloses distribution of an unclassified megaplasmid group across bacterial species Abstract: Analysis of the complete nucleotide sequence of plasmid pM7012 from 2,4-dichlorophenoxyacetic-acid (2,4-D)-degrading bacterium Burkholderia sp. M701 revealed that the plasmid had 582?142 bp, with 541 putative protein-coding sequences and 39 putative tRNA genes for the transport of the standard 20 aa. pM7012 contains sequences homologous to the regions involved in conjugal transfer and plasmid maintenance found in plasmids byi_2p from Burkholderia sp. YI23 and pBVIE01 from Burkholderia sp. G4. No relaxase gene was found in any of these plasmids, although genes for a type IV secretion system and type IV coupling proteins were identified. Plasmids with no relaxase gene have been classified as non-mobile plasmids. However, nucleotide sequences with a high level of similarity to the genes for plasmid transfer, plasmid maintenance, 2,4-D degradation and arsenic resistance contained on pM7012 were also detected in eight other megaplasmids (~600 or 900 kb) found in seven Burkholderia strains and a strain of Cupriavidus, which were isolated as 2,4-D-degrading bacteria in Japan and the United States. These results suggested that the 2,4-D degradation megaplasmids related to pM7012 are mobile and distributed across various bacterial species worldwide, and that the plasmid group could be distinguished from known mobile plasmid groups.",
Arsenic,1704101,Nano and Micro ZVI in Aqueous Media: Copper Uptake and Solution Behavior Abstract: ,
Arsenic,1340106,"Association between type 2 diabetes and chronic arsenic exposure in drinking water: A cross sectional study in Bangladesh Abstract: <strong>BACKGROUND: </strong>Chronic exposure to high level of inorganic arsenic in drinking water has been associated with Type 2 Diabetes (T2D). Most research has been ecological in nature and has focused on high levels of arsenic exposure with few studies directly measuring arsenic levels in drinking water as an index of arsenic exposure. The effect of low to moderate levels of arsenic exposure on diabetes risk is largely unknown thus our study is adding further knowledge over previous works.<br /><br /><strong>METHODS: </strong>This cross sectional study was conducted in 1004 consenting women and men from 1682 eligible participants yielding a participation rate of 60%. These participants are aged >30 years and were living in Bangladesh and had continuously consumed arsenic-contaminated drinking water for at least 6 months. T2D cases were diagnosed using glucometer following the new diagnostic criteria (Fasting Blood Glucose > 126 mg/dl) from the WHO guideline (WHO 2006), or a self-reported physician diagnosis of type 2 diabetes. Association between T2D and chronic arsenic exposure was estimated by multiple logistic regression with adjustment for age, sex, education, Body Mass Index (BMI) and family history of T2D.<br /><br /><strong>RESULTS: </strong>A total of 1004 individuals participated in the study. The prevalence of T2D was 9% (95% CI 7-11%). After adjustment for diabetes risk factors, an increased risk of type 2 diabetes was observed for arsenic exposure over 50 ?g/L with those in the highest category having almost double the risk of type 2 diabetes (OR=1.9 ; 95% CI 1.1-3.5). For most levels of arsenic exposure, the risk estimates are higher with longer exposure; a dose-response pattern was also observed.<br /><br /><strong>CONCLUSIONS: </strong>These findings suggest an association between chronic arsenic exposure through drinking water and T2D. Risks are generally higher with longer duration of arsenic exposure. The risk of T2D is highest among those who were exposed to the highest concentration of arsenic for more than 10 years.",
Arsenic,1251378,"Oxidative stress induces heme oxygenase-1 immunoreactivity in Müller cells of mouse retina in organ culture Abstract: <strong>PURPOSE: </strong>Heme oxygenase (HO)-1 immunoreactivity (IR) was examined in normal untreated retina and in retinal explants after in vitro treatment with stress agents.<br /><br /><strong>METHODS: </strong>Enucleated eyes from young adult C3H mice were immediately fixed and cryosectioned and the retina sections processed for immunocytochemistry with antibodies against HO-1 and glial fibrillary acidic protein (GFAP). From other eyes retinas were isolated and maintained in organ culture, either untreated for 4 days maximum or for 21 hours during which the explants were treated the first 3 hours with selected doses of sodium arsenate or hydrogen peroxide. Thereafter, the explants were processed identically with the normal tissue.<br /><br /><strong>RESULTS: </strong>In the normal retina, HO-1 and GFAP IR was very low. The culturing itself resulted in an increase in both HO-1 and GFAP immunolabeling in Müller cells of explanted retinas. Both sodium arsenate and hydrogen peroxide further induced strong HO-1 IR in Müller cells but not in other retinal cells. In contrast to HO-1, GFAP staining in Müller cells was not altered as a result of treatment, either by sodium arsenate or hydrogen peroxide at any concentration used.<br /><br /><strong>CONCLUSIONS: </strong>The results show for the first time that HO-1 can be induced in the retina in vitro by conditions of oxidative stress and that enzyme expression is confined exclusively to Müller cells.",
Arsenic,2343556,"Hydrogenic Heavy Metals Contamination of Fluvisols in the Middle Cis-Urals Region, Russia Abstract: In 1999, the Perm region ranked eighth among Russian regions in terms of technogenic load per unit of area (4.4 t/km(2)). The situation in the city of Perm is especially unfavorable in ecological terms due to aerial contamination and hydrogenic contamination, because of industrial wastes entering the small rivers that are tributaries of the Kama river. It was revealed that fluvisols of the city of Perm are contaminated by heavy metals of hydrogenic origin because of the unpurified sewage water entering them. The fluvisols of the city of Perm are contaminated by heavy metals of hydrogenic origin because of the unpurified sewage water entering them. Content of HMs in fine earth showed the deficit and excess compared with European Soil Clarke and Local Background. In relation to European Soil Clarkes elements can be divided into three groups: (1) scarce elements forming negative geochemical anomaly, (2) ""normal"" elements, which does not differ significantly from Clarke, (3) excess elements forming positive geochemical anomaly. Scarce elements include rubidiumand arsenic. ""Normal"" elements are yttrium, gallium, zirconium and lead. Excess elements are nickel, copper, zinc, strontium and chromium. In the fluvisols, the Ferohrensteins are formed. Some elements are concentrated in the Fe-rohrensteins, and some others are not concentrated in them or are found in low concentrations. In Ferohrensteins the highly active group comprises As, Zn, Ni, Cu, Cr, and Pb; the moderately active one is represented by Sr, Nb, Ga, and Y; and the inert group contains Zr and Rb. The contents of some chemical elements in Fe-rohrensteins are much greater than those in the fine earth. The Pb and Zn contents in Fe-rohrensteins of the soil of small rivers basin are 440 and 890 mg/kg, respectively. In Fe-rohrensteins, the Pb and Zn contents are 42 % and 17 % of their concentrations in fine earth, respectively. Since some part of heavy metals is precipitated at the redox microbarriers around concretions (Fe-rohrensteins), it is removed from the biological cycle.",
Arsenic,1018667,"Arsenic and chromium enhance transformation of bovine papillomavirus DNA-transfected C3H/10T1/2 cells Abstract: Tumor promoters such as phorbol esters, teleocidin and okadaic acid increase the numbers of multilayered, transformed foci produced by BPV DNA-transfected C3H/10T1/2 cells. We questioned whether arsenic and chromium, which are known human carcinogens also enhance transformation of BPV DNA-transfected C3H/10T1/2 cells. Cr(III) potassium sulfate at 100 microM enhanced transformation by 1.4-fold, but Cr(VI) as potassium chromate did not enhance transformation, although toxicity of potassium chromate may have prevented enhancement of transformation. Sodium arsenite (As(III) at 5 microM and sodium arsenate (As(V)) at 25 microM both enhanced neoplastic transformation by 6-fold. By comparison, in previous studies, sodium orthovanadate (V(IV)) or vanadyl sulfate (V(IV)) at 4 microM enhanced numbers of transformed foci by 25-50-fold. The comparatively strong enhancement of transformation by vanadium and phorbol esters suggests that neoplastic transformation may occur by mechanisms that are common to these compounds including alteration of tyrosine phosphorylation.",
Arsenic,1252558,"Detection of hyperdiploidy and breakage affecting the 1cen-1q12 region of cultured interphase human lymphocytes treated with various genotoxic agents Abstract: Chromosomal aberrations are associated with cancer, birth defects, and pregnancy loss. Previous studies using banding techniques have revealed that chromosomal alterations induced in human peripheral lymphocytes by many genotoxic agents occur nonrandomly throughout the genome. One of the regions prone to breakage is the centromeric heterochromatin of chromosome 1. We have developed a fluorescence in situ hybridization (FISH) procedure using tandem DNA probes to distinguish hyperdiploidy from breakage occurring in this region. Interphase nuclei exhibiting breakage or exchanges affecting the 1cen-1q12 region can readily be distinguished from nuclei hyperdiploid for this chromosome by identifying the number and location of the hybridization signals. This hybridization approach was tested using cultured human lymphocytes treated with a series of known aneuploidy-inducing agents (colchicine, diethylstilbestrol, and vincristine sulfate), several potent clastogens (ionizing radiation, mitomycin C, and etoposide), as well as sodium arsenite and hydroquinone, agents that have been reported to have relatively weak aneuploidy-inducing and clastogenic activity. Significant increases in chromosomal alterations were seen with all agents tested and the results were generally consistent with those previously seen using standard cytogenetic techniques. Treatment with colchicine, diethylstilbestrol, and vincristine sulfate resulted in high frequencies of primarily hyperdiploid nuclei, and cells exposed to radiation, mitomycin C, and etoposide exhibited elevated frequencies of breakage affecting the 1cen-1q12 region. Sodium arsenite and hydroquinone induced relatively minor but significant increases in both hyperdiploidy and breakage. These results indicate that this tandem labeling approach can be used to distinguish aneuploidy-inducing agents from those causing breakage in interphase human cells and may be a valuable procedure for monitoring human populations exposed to genotoxic agents.",
Arsenic,1508641,"Osteoresorptive arsenic intoxication Abstract: A 47-year-old woman consulted her dermatologist complaining whole body dermatitis, urticaria and irritating bullous eruptions on the plantar and side surfaces of her feet. She had had multiple hypopigmented spots on her skin since her early adulthood. The patient was treated with topical medication without significant improvement of symptoms. One year later she suffered a myocardial infarction, accompanied by refractory anaemia. At the age of 49, a breast cancer was diagnosed and shortly thereafter her last menstruation occurred. At age 50years, upon complaint of weight loss despite normal food intake, Hashimoto thyroiditis with latent hyperthyroidism, vitamin D insufficiency with secondary hyperparathyroidism, and poikilocytic anaemia with anisochromia, hypochromia, anisocytosis, elliptocytes, drepanocytes, dacryocytes, acanthocytes, echinocytes, schizocytes, stomatocytes and target cells were diagnosed. The osteodensitometric and laboratory examinations revealed osteoporosis with sustained elevation of urinary Dipyridinolin-crosslinks (u-Dpd), and urinary arsenic (u-As) of 500?g/l (equivalent to 0.5 parts per million-ppm, 2.5?g/mg creatinine/dl, u-As: Phosphate of 26?g/mmol; the estimated bone As:P and As/kg body weight were 500?g/g and 11.3mg/kg, respectively). Thalassemia, immunoglobinopathy and iron deficiency were excluded. Supplementation with oral vitamin D and calcium, and antiresorptive therapy with intravenous zolendronate normalised the u-Dpd, significantly decreased the urinary arsenic concentration, and cured the anemia and the urticaria. A diagnosis of osteoresorptive arsenic intoxication (ORAI) was established.",
Arsenic,1018883,"Arsenic induces expression of the multidrug resistance-associated protein 2 (MRP2) gene in primary rat and human hepatocytes Abstract: Metals, such as arsenic or cadmium, have recently been demonstrated to interact with metabolic pathways, including phase I and phase II enzymes and the phase III efflux pump P-glycoprotein. In the present study, we investigated the effects of heavy metals and metalloids on the expression of the multidrug resistance-associated protein 2 (MRP2), a major hepatic transporter. Treatment of primary rat hepatocytes by sodium arsenite [As(III)], sodium arsenate and potassium antimony tartrate, but not cadmium chloride, was shown to markedly increase MRP2 mRNA and protein levels; As(III)-mediated induction was dose- and time-dependent and paralleled a strong increase in MRP2 amounts as assessed by Western blotting. As(III) was also demonstrated to markedly up-regulate MRP2 gene expression in primary human hepatocytes. MRP2 mRNA induction occurring in As(III)-treated rat hepatocytes was fully blocked by actinomycin D, indicating that it required active gene transcription. It was associated with an activation of the c-Jun N-terminal kinase pathway and with a reduction of cellular glutathione levels. Quercetin, a flavonoid compound known to block As(III)-related induction of P-glycoprotein, was also found to prevent up-regulation of MRP2 gene expression in rat hepatocytes exposed to As(III). Such an effect was unlikely to be due to alteration of JNK pathway since quercetin failed to abolish As(III)-induced JNK phosphorylation. It may rather be linked to the increase of cellular glutathione levels by quercetin, thus limiting the depleting effects of As(III) on glutathione amounts. Finally, these results confirm that some metals strongly regulate expression of detoxifying proteins, including biliary drug transporters.",
Arsenic,1031750,"Arsenite and cadmium(II) as probes of glucocorticoid receptor structure and function Abstract: Low concentrations of arsenite, but not arsenate, and Cd2+ blocked steroid binding to the glucocorticoid receptors of HTC cells. Inhibition by arsenite was faster and occurred at lower concentrations than for Cd2+. Half-maximal inhibition of [3H]dexamethasone binding was seen after a 30-min preincubation with approximately 7 microM arsenite. The effect of arsenite and of Cd2+ appears to be mediated by a reaction with vicinal dithiols of the receptor as shown by (a) the reversal of arsenite inhibition by much lower concentrations of dithiothreitol (approximately 0.1 mM) than of beta-mercaptoethanol (approximately 10 mM); (b) the ability of both arsenite and Cd2+ to block [3H]dexamethasone 21-mesylate labeling of receptors but not of other thiol-containing proteins; and (c) the known selectivity of arsenite and of Cd2+ for reactions with vicinal dithiols. Arsenite forms a tight complex with these vicinal dithiols since the removal of loosely associated arsenite by gel exclusion chromatography did not reverse the inhibition of steroid binding. The effect of other ions on steroid binding was also examined. Half-maximal inhibition of binding occurred with approximately 5 microM selenite, whereas up to 300 microM Zn2+ was without effect. Much higher concentrations of arsenite were required for effects on unactivated and activated complexes. Arsenite slowly induced a loss of unactivated complexes but rapidly inhibited a portion of the DNA binding of activated complexes. Any effect on activation occurred at arsenite concentrations equal to or higher than those that inhibited DNA binding. In contrast, Cd2+ concentrations similar to those that block steroid binding caused a biphasic loss of unactivated complexes and a marginal loss of activated complexes. This is the first report of effects of arsenite on glucocorticoid receptors. These results confirm directly our earlier hypothesis that steroid binding to rat glucocorticoid receptors involves a vicinal dithiol (Miller, N. R., and Simons, S. S., Jr. (1988) J. Biol. Chem. 263, 15217-15225) and show that arsenite is a potent new reagent for probing receptor structure and function.",
Arsenic,710962,"Inhibition of liver x receptor/retinoid X receptor-mediated transcription contributes to the proatherogenic effects of arsenic in macrophages in vitro Abstract: To determine whether arsenic inhibits transcriptional activation of the liver X receptor (LXR)/retinoid X receptor (RXR) heterodimers, thereby impairing cholesterol efflux from macrophages and potentially contributing to a proatherogenic phenotype.<br /><br /> Arsenic is an important environmental contaminant and has been linked to an increased incidence of atherosclerosis. Previous findings showed that arsenic inhibits transcriptional activation of type 2 nuclear receptors, known to heterodimerize with RXR. Environmentally relevant arsenic doses decrease the LXR/RXR ligand-induced expression of the LXR target genes (ABCA1 and SREBP-1c). Arsenic failed to decrease cAMP-induced ABCA1 expression, suggesting a selective LXR/RXR effect. This selectivity correlated with the ability of arsenic to decrease LXR/RXR ligand-induced, but not cAMP-induced, cholesterol efflux. By using chromatin immunoprecipitation assays, we found that arsenic inhibits the ability of LXR/RXR ligands to induce activation markers on the ABCA1 and SREBP-1c promoters and blocks ligand-induced release of the nuclear receptor coexpressor (NCoR) from the promoter. Arsenic did not alter the ability of LXR to transrepress inflammatory gene transcription, further supporting our hypothesis that RXR is the target for arsenic inhibition.<br /><br /> Exposure to arsenic enhances the risk of atherosclerosis. We present data that arsenic inhibits the transcriptional activity of the liver X receptor, resulting in decreased cholesterol-induced gene expression and efflux from macrophages. Therefore, arsenic may promote an athersclerotic environment by decreasing the ability of macrophages to efflux excess cholesterol, thereby favoring increased plaque formation.",
Arsenic,1029071,"Applying the common sense model to measure representations of arsenic contaminated well water Abstract: Theory-based research is needed to understand how people respond to environmental health risk information. Both the common sense model (CSM) of self-regulation and the mental models approach propose that information shapes individuals' personal understandings that, in turn, influence their decisions and actions. We compare these frameworks and explain how the CSM was applied to describe and measure mental representations of arsenic contaminated well water. Educational information, key informant interviews, and environmental risk literature were used to develop survey items to measure dimensions of cognitive representations (identity, cause, timeline, consequences, control) and emotional representations. Surveys mailed to 1,067 private well users with moderate and elevated arsenic levels yielded an 84 % response rate (n = 897). Exploratory and confirmatory factor analyses of data from the elevated arsenic group identified a factor structure that retained the CSM representational structure and was consistent across moderate and elevated arsenic groups. The CSM has utility for describing and measuring representations of environmental health risks, thus supporting its application to environmental health risk communication research.",
Arsenic,2149113,"Spatial modeling of ecological areas by fitting the limiting factors for As in the vicinity of mine, Serbia Abstract: Elevated arsenic (As) concentrations in soil are often found in the vicinity of certain mineral deposits that have been, or are currently, under exploitation, regardless of the target resource. Detailed study of such areas for safe agriculture requires considerable financial costs and long periods of time. Application of an appropriate spatial model that describes the behavior of arsenic in soil and plants can significantly ease the whole investigation process. This paper presents a model of ecological security of an area that, in the past, was an antimony mine and has a naturally high content of arsenic. For simulation and modeling the geographic information science (GIS) technology with the inserted predictors influencing the accessibility of As and its content in plants was used. The results obtained were the following: (1) a categorization of contaminated soils according to soil properties was developed; (2) the proposed methodology allows focusing on particular suspect area saving an energy and human resource input; and (3) new safe areas for growing crops in contaminated area were modeled. The application of the proposed model of As solubility to various crops grown around a former antimony mine near the village of Lisa, southwest Serbia showed that significant expansion of the areas suitable for growing potato, raspberry, and pasture was possible.",
Arsenic,1019941,"Characterization of gene expression changes associated with MNNG, arsenic, or metal mixture treatment in human keratinocytes: application of cDNA microarray technology Abstract: The identification of molecular markers related to critical biological processes during carcinogenesis may aid in the evaluation of carcinogenic potentials of chemicals and chemical mixtures. Work from our laboratory demonstrated that a single treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) enhanced spontaneous malignant transformation of the human keratinocyte cell line RHEK-1. In contrast, chronic low-level exposure of cells to arsenic alone or in a mixture containing arsenic, cadmium, chromium, and lead inhibited malignant conversion. To identify changes in gene expression that influence these different outcomes, cDNA microarray technology was used. Analysis of multiple human arrays in MNNG-transformed RHEK-1 cells, designated OM3, and those treated with arsenic or the arsenic-containing metal mixture showed unique patterns of gene expression. Genes that were overexpressed in OM3 included oncogenes, cell cycle regulators, and those involved in signal transduction, whereas genes for DNA repair enzymes and inhibitors of transformation and metastasis were suppressed. In arsenic-treated cells, multiple DNA repair proteins were overexpressed. Mixture-treated cells showed increased expression of a variety of genes including metallothioneins and integrin 4. These cells showed decreased expression of oncogenes, DNA repair proteins, and genes involved in the mitogen-activated protein kinase pathway. For comparison we are currently analyzing gene expression changes in RHEK-1 cells transformed by other means. The goal of these studies is to identify common batteries of genes affected by chemical modulators of the carcinogenic process. Mechanistic studies may allow us to correlate alterations in their expression with sequential stages in the carcinogenic process and may aid in the risk assessment of other xenobiotics.",
Arsenic,1017381,"L-cysteine as a regulator for arsenic-mediated cancer-promoting and anti-cancer effects Abstract: Previous studies have shown that activities of tyrosine kinases and secretion of the active form of matrix metalloproteinase-2 (MMP-2) are correlated with promotion of tumor growth, while apoptotic cell death in cancer cells is correlated with anti-cancer effects. Although arsenic has been reported to have both cancer-promoting and anti-cancer effects, the mechanisms of the arsenic-mediated bidirectional effects remain unknown. We examined the effects of arsenic on both proto-oncogene c-RET-transfected NIH3T3 cells with benign characters and oncogenic RET-MEN2A-transfected NIH3T3 cells with malignant characters. Arsenic promoted not only c-RET tyrosine kinase activity but also genetically activated RET-MEN2A kinase activity with promotion of dimer formation of RET proteins. Arsenic also increased secretion of the active form of MMP-2 in both RET-MEN2A-transfectants and c-RET-transfectants. On the other hand, arsenic promoted poly-(ADP-ribose) polymerase (PARP) degradation and cell death in both malignant and non-malignant cells. Interestingly, l-cysteine inhibited the arsenic-mediated tumor-promoting effects (activation of kinases and MMP-2 secretion) but not arsenic-mediated anti-cancer effects (PARP degradation and cell death). Our results suggest redox-linked regulation of arsenic-mediated activities of kinases and MMP-2 secretion but not arsenic-mediated cell death. Our results also suggest that l-cysteine is an ideal supplement that inhibits arsenic-mediated tumor-promoting effects without affecting arsenic-mediated anti-cancer effects.",
Arsenic,627131,"Oxidation and methylation status determine the effects of arsenic on the mitotic apparatus Abstract: We investigated the spindle inhibitory properties of six arsenicals differing in their methylation or oxidation state. Human lymphoblasts were exposed for 6 h to either sodium arsenate (NaAs(V)), sodium arsenite (NaAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), dimethylarsinic acid (DMA(V)), or dimethylarsinous acid (DMA(III)). After exposure slides were prepared, and the mitotic indices (MI) were assessed. We also exposed tubulin directly to each arsenical and spectrophotometrically measured its effect on polymerization. NaAs(V) caused a small but significant increase in MI. MMA(V) also caused only a slight increase in MI that just reached statistical significance. In contrast, DMA(V) caused a significant increase in MI, producing approximately 75% the MI of demecolcine and approximately 4 times the MI of the control. NaAs(III) had no significant effect on MI and was quite toxic. MMA(III) induced more than a twofold increase in MI compared to the control, which was about 40% that caused by demecolcine. On a micromolar basis, MMA(III) was the most potent of the arsenicals tested. DMA(III) gave inconsistent results. None of the pentavalent arsenicals had a substantial effect (either inhibition or enhancement) on GTP-induced polymerization of tubulin. In contrast, NaAs(III) inhibited polymerization at concentrations of 1 mM and above and MMA(III) and DMA(III) at 10 microM and above. Taken together, these results present a complex picture of how arsenicals may affect cells. These studies demonstrate that the metabolites of arsenic are active not only as chromosome breaking and DNA damaging agents but can also interfere with cell division via tubulin disruption.",
Arsenic,1357403,"Aplastic Anemia and Pesticides. An Etiologic Association? Abstract: The possible etiologic association between exposure to organophosphate and organochlorine pesticides and aplastic anemia was examined in this review of 280 cases, which were reported in predominantly English language medical literature over the past 30 years. The issues examined included specific pesticides, whether the exposure was occupational (62% were), and the length of time to disease onset from the incident of exposure (mean latency was 5 months). Of the 280 reported cases, 90 cases contained information on the sex and age of the people presumed to have pesticide associated aplastic anemia. Affected people ranged in age from 2 to 80 years, with a mean age of 34. Approximately twice as many men as women were affected. Of the 90 cases, 60 reported exposure to organochlorine pesticides, 13 to carbamate (463774) and organophosphates, eight to PCP (87865), four to fumigants and agrochemicals, and one to arsenic (7440382). Problems reported with determining an etiologic relationship between pesticide exposure and aplastic anemia included an inconsistent definition of aplastic anemia and a lack of cohort studies. Underreporting by physicians and recall bias affected epidemiological studies. The authors conclude that there is an etiologic association between pesticides, especially organophosphates, and aplastic anemia. Organophosphates reportedly caused a significant dose response depression of bone marrow stem cell colony formation in humans, which can depress erythrocyte precursors. Chromosomal aberrations in human lymphocyte cultures were reportedly caused by malathion (121755), methyl-bromide (74839), and chloropicrin (76062). Compared with men not exposed to pesticides, men exposed to chlorinated pesticides occupationally had higher levels of immunoglobulin-G. The authors warn that other nonpesticide environmental and occupational agents, such as benzene, may also increase the risk of aplastic anemia. The authors state that physicians should routinely question patients about their occupational and environmental exposure histories.",
Arsenic,2347624,"Enrichment and purification of marine polyphenol phlorotannins using macroporous adsorption resins Abstract: Phlorotannins are one of the most important bioactive polyphenols; however, their purification using chromatographic methods has not been explored. Here, we studied purification of phlorotannins from the crude phlorotannin extract (CPhE) of the brown seaweed Ecklonia cava using macroporous adsorption resins. For purification of phlorotannins, four resins (HP-20, SP-850, XAD-7HP, and XAD-2) were screened. Among them, HP-20 resin showed the highest adsorption and desorption capacities. In static adsorption tests, the adsorption capacity of HP-20 increased with increasing temperature (25-45 degrees C). Optimal conditions for the dynamic experiments can be summarized as follows: total phlorotannin content (TPhC) in loading solution: 1.5 mg PGE/mL, processing volume: 4 BV, flow rate: 1 mL/min, temperature: 45 degrees C, desorption solvent: 40% ethanol solution. After purification, TPhC (452 mg PGE/g) and arsenic (180 mu g/g) of CPhE increased and decreased to 905 mg PGE/g and 48 mu/g, respectively. Recovery rate of phlorotannins from CPhE was 92%.",
Arsenic,2337227,"Arsenic-tolerant plant-growth-promoting bacteria isolated from arsenic-polluted soils in South Korea Abstract: The Janghang smelter in Chungnam, South Korea started in 1936 was subsequently shutdown in 1989 due to heavy metal (loid) pollution concerns in the vicinity. Thus, there is a need for the soil in the area to be remediated to make it usable again especially for agricultural purposes. The present study was conducted to exploit the potential of arsenic (As)-tolerant bacteria thriving in the vicinity of the smelter-polluted soils to enhance phytoremediation of hazardous As. We studied the genetic and taxonomic diversity of 21 As-tolerant bacteria isolated from soils nearer to and away from the smelter. These isolates belonging to the genera Brevibacterium, Pseudomonas, Microbacterium, Rhodococcus, Rahnella, and Paenibacillus, could tolerate high concentrations of arsenite (As(III)) and arsenate (As(V)) with the minimum inhibitory concentration ranging from 3 to &gt;20 mM for NaAsO2 and 140 to 310 mM NaH2AsO4?·?7H2O, respectively. All isolates exhibited As(V) reduction except Pseudomonas koreensis JS123, which exhibited both oxidation and reduction of As. Moreover, all the 21 isolates produced indole acetic acid (IAA), 13 isolates exhibited 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, 12 produced siderophore, 17 solubilized phosphate, and 13 were putative nitrogen fixers under in vitro conditions. Particularly, Rhodococcus aetherivorans JS2210, P. koreensis JS2214, and Pseudomonas sp. JS238 consistently increased root length of maize in the presence of 100 and 200 ?M As(V). Possible utilization of these As-tolerant plant-growth-promoting bacteria can be a potential strategy in increasing the efficiency of phytoremediation in As-polluted soils.",
Arsenic,1579258,"Preparation and evaluation of chitosan beads immobilized with iron(III) for the removal of As(III) and As(V) from water Abstract: The crosslinked chitosan-Fe(III) (Ch-FeCL) adsorbent was developed using Fe(III) immobilized on chitosan beads. After drying, the beads presented a diameter of approximately 1 mm and are stable in air. The adsorption behavior of As(III) and As(V) on the Ch-FeCL was evaluated at pH 7 by studies conducted in batch and in columns. Maximum adsorption capacities estimated by the Langmuir adsorption model were 21.24 and 27.59 mg g-1 for As(III) and As(V), respectively. Adsorption kinetics is described by the pseudo second order kinetic equation. The results of column adsorption indicated that arsenic was not found in the effluent solution from roughly 60 and 759 bed volumes for As(III) and As(V), respectively. Results were satisfactory when employing the adsorbent for removal of As(III) and As(V) from groundwater, tap water and river water samples.",
Arsenic,2278755,"Mechanism of arsenic removal using chitosan and nanochitosan Abstract: Chitosan, a natural polysaccharide copolymer of glucosamine and N-acetyl-glucosamine, possesses one free primary amine and two free hydroxyl groups on each glucosamine unit. It has a polycationic nature and an abundance of amine functional groups. The sorption equilibrium and kinetics of arsenate onto chitosan flakes have been studied. The effect of pH on the adsorption capacity and the uptake kinetics is an important parameter to investigate the adsorption mechanism of anionic species such as arsenate ions on the protonated amine groups of chitosan. The equilibrium sorption and batch kinetic studies of arsenate ions on chitosan were performed at initial As concentration of 250-11,000 ?g L(-1) and initial pH ranging from pH=3.50-5.50. The experimental results showed that initially for approximately the first 30 min there is a rapid and high adsorption of arsenate ions onto the chitosan leading to a maximum uptake capacity after this short time. However, this stage is followed by a slow desorption of arsenate from the chitosan with a steady increase in solution pH. A novel reversible pseudo-first order kinetic model was developed and applied to correlate this newly reported adsorption-desorption phenomenon. The physical and chemical properties of chitosan were studied and presented in terms of its surface and structural properties such as the degree of deacetylation, crystallinity, surface charge and its swelling properties.",
Arsenic,1328942,"Environmental burden of disease: HRQoL and statistical perspectives Abstract: Environmental toxicity and pollution mingled with substandard sanitation and public health practice can lead to serious health problems. Some of these toxics can be identified and subjected to preventive measures but together with some other major factors they form the environmental burden of disease, more seriously in developing countries. As a result, in health related quality of life risk assessments, especially relating to cancer of various types, as well as chronic and intestinal diseases, we need to incorporate toxicology as well as environmental epidemiology. Statistical perspectives in this challenging task are appraised with special attention to the arsenite contamination of the groundwater problem",
Arsenic,1597355,"Human sperm and other seminal constituents in male infertile patients from arsenic and cadmium rich areas of Southern Assam Abstract: In the present study the occurrence of two heavy metals, arsenic and cadmium, have been reported in the drinking water and seminal plasma of infertile male patients as compared to a control group. The study originated from a survey of geogenic groundwater contamination with the heavy metals arsenic and cadmium in Southern Assam, India as an increase in the incidence of male infertility was being reported from these areas. According to WHO protocol, patients with sperm concentration?<?20x10(6)/ml were selected as cases (oligozoospermic and azoospermic), and those with?>?20x10(6)/ml, without any extreme pathological disorders and having fathered a child within 1-2 years of marriage were the control (normozoospermic) group. The study reports an inverse relationship between total sperm count and heavy metal content in drinking water as well as seminal plasma of the subjects. Moreover, a high correlation between altered semenological parameters and lower expression of accessory sex gland markers like fructose, acid phosphatase, and neutral ?-glucosidase in the seminal plasma of patients is reported. The study also highlights significant differences of the sperm function parameters like hypo-osmotic swelling, acrosome reaction, and nuclear chromatin decondensation in the patient group as compared to controls. These findings are significant as they address a likely association between heavy metal stress and altered sperm function as well as seminal enzyme inhibition.",
Arsenic,501813,"Effect of arsenic on immunity, oxidative enzyme and various hematological parameters in cross bred calves Abstract: An experiment was conducted on crossbred male calves to study the effect of arsenic (As) on immunity status and certain hematological parameters. Ten crossbred male calves of 3-4 months of age were distributed into two equal groups. Group I was kept as control, whereas, group 11 was supplemented daily with 50 ppm As (as AS,03) up to 90 days, in the diet. Calves of both groups were fed as per ICAR standards and their requirements were fulfilled by feeding concentrate mixture and green oats. All calves were kept under similar managemental conditions. Blood samples were collected at fortnightly intervals to estimate various haematological parameters and superoxide dismutase (SOD) enzyme activity. Serum Ig and serum glutamic pyruvate transaminase (SGPT) were also measured. Cell-mediated immune responses of the calves were monitored at 0, 45 and 90 of experimental feeding, through lymphocyte proliferation. No change in blood total leukocyte counts (TLC), differential leukocyte counts (DLC), packed cell volume (PCV), haemoglobin (Hb) and SGPT was observed with As supplementation. A decrease in SOD activity was noticed in group 11 calves. Stimulation index (SI) for lymphocyte proliferation decreased from 1.14 to 0.79 in group 11 calves during 90 days experimental feeding, whereas, there was no change in SI values in group I indicating significant decrease in immune response of As supplemented calves. Blood As concentration increased in group 11 calves with the decrease in immune response. Short term supplementation of As to growing calves suggested suppressive effects on cell-mediated immunity. However, long term experiments are required to demonstrate clearly the efects of this toxic metal in calves.",
Arsenic,1579293,"Arsenite-induced ROS/RNS generation causes zinc loss and inhibits the activity of poly(ADP-ribose) polymerase-1 Abstract: Arsenic enhances the genotoxicity of other carcinogenic agents such as ultraviolet radiation and benzo[a]pyrene. Recent reports suggest that inhibition of DNA repair is an important aspect of arsenic cocarcinogenesis, and DNA repair proteins such as poly(ADP ribose) polymerase (PARP)-1 are direct molecular targets of arsenic. Although arsenic has been shown to generate reactive oxygen/nitrogen species (ROS/RNS), little is known about the role of arsenic-induced ROS/RNS in the mechanism underlying arsenic inhibition of DNA repair. We report herein that arsenite-generated ROS/RNS inhibits PARP-1 activity in cells. Cellular exposure to arsenite, as well as hydrogen peroxide and NONOate (nitric oxide donor), decreased PARP-1 zinc content, enzymatic activity, and PARP-1 DNA binding. Furthermore, the effects of arsenite on PARP-1 activity, DNA binding, and zinc content were partially reversed by the antioxidant ascorbic acid, catalase, and the NOS inhibitor, aminoguanidine. Most importantly, arsenite incubation with purified PARP-1 protein in vitro did not alter PARP-1 activity or DNA-binding ability, whereas hydrogen peroxide or NONOate retained PARP-1 inhibitory activity. These results strongly suggest that cellular generation of ROS/RNS plays an important role in arsenite inhibition of PARP-1 activity, leading to the loss of PARP-1 DNA-binding ability and enzymatic activity.",
Arsenic,1070492,"Arsenic methylation, GSTO1 polymorphisms, and metabolic syndrome in an arseniasis endemic area of southwestern Taiwan Abstract: Previous studies have shown that hair arsenic (As) levels are associated with an increased prevalence of metabolic syndrome (MetS), which is a strong predictor for type 2 diabetes. The objective of this study was to evaluate whether urinary arsenic methylation is related to MetS in an arseniasis endemic area of southwestern Taiwan, taking genetic factors into account. Subjects were from a community-based cohort recruited in 1990 from three villages in Putai Township. In 2002-2003, we successfully followed 247 subjects and measured their urinary arsenic species including inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), as well as the coding region polymorphisms of three genes known to involve in arsenic methylation. Results showed that subjects of MetS had a history of consuming well water of higher arsenic concentration as compared to those without MetS. We also found a significant association between urinary arsenic species and risk for MetS, where the odds ratio of MetS was increased with decreasing proportion of MMA and low rate of primary methylation (defined as MMA/inorganic As). The increased risk associated with low primary methylation rate was further modified by the GSTO1 A140D polymorphism, with the D allele carriers showing a slightly higher risk for MetS. Our results suggest that a low MMA% is associated with increased risk for MetS among As-exposed subjects and the genetic polymorphism of GSTO1, an enzyme responsible for the reduction of pentavalent arsenic species, may also play a modest modification role.",
Arsenic,1070486,"Multi-trace element levels and arsenic speciation in urine of e-waste recycling workers from Agbogbloshie, Accra in Ghana Abstract: To understand human contamination by multi-trace elements (TEs) in electrical and electronic waste (e-waste) recycling site at Agbogbloshie, Accra in Ghana, this study analyzed TEs and As speciation in urine of e-waste recycling workers. Concentrations of Fe, Sb, and Pb in urine of e-waste recycling workers were significantly higher than those of reference sites after consideration of interaction by age, indicating that the recycling workers are exposed to these TEs through the recycling activity. Urinary As concentration was relatively high, although the level in drinking water was quite low. Speciation analysis of As in human urine revealed that arsenobetaine and dimethylarsinic acid were the predominant As species and concentrations of both species were positively correlated with total As concentration as well as between each other. These results suggest that such compounds may be derived from the same source, probably fish and shellfish and greatly influence As exposure levels. To our knowledge, this is the first study on human contamination resulting from the primitive recycling of e-waste in Ghana. This study will contribute to the knowledge about human exposure to trace elements from an e-waste site in a less industrialized region so far scantly covered in the literature.",
Arsenic,2337221,"Sprinkler irrigation of rice fields reduces grain arsenic but enhances cadmium Abstract: Previous studies have demonstrated that rice cultivated under flooded conditions has higher concentrations of arsenic (As) but lower cadmium (Cd) compared to rice grown in unsaturated soils. To validate such effects over long terms under Mediterranean conditions a field experiment, conducted over 7 successive years was established in SW Spain. The impact of water management on rice production and grain arsenic (As) and cadmium (Cd) was measured, and As speciation was determined to inform toxicity evaluation. Sprinkler irrigation was compared to traditional flooding. Both irrigation techniques resulted in similar grain yields (~3000kggrainha(-1)). Successive sprinkler irrigation over 7years decreased grain total As to one-sixth its initial concentration in the flooded system (0.55 to 0.09mgAskg(-1)), while one cycle of sprinkler irrigation also reduced grain total As by one-third (0.20mgkg(-1)). Grain inorganic As concentration increased up to 2 folds under flooded conditions compared to sprinkler irrigated fields while organic As was also lower in sprinkler system treatments, but to a lesser extent. This suggests that methylation is favored under water logging. However, sprinkler irrigation increased Cd transfer to grain by a factor of 10, reaching 0.05mgCdkg(-1) in 7years. Sprinkler systems in paddy fields seem particularly suited for Mediterranean climates and are able to mitigate against excessive As accumulation, but our evidence shows that an increased Cd load in rice grain may result.",
Arsenic,1936167,"Urban water supply and management Abstract: Population growth and rapid urbanization lead to considerable stress on already depleting water resources. A great challenge for water authorities of urban cities is to supply adequate and reliable safe water to all consumers. In most of the developing countries water scarcity and high demands have led the water authorities to resort to intermittent supplies. Surface and groundwater are the major sources of supply in urban cities. The direct consequences of intermittent supplies and poor sanitation practices are several incidences of water borne diseases posing public health risk. In order to minimize the supply-demand gap and to assure good quality of water, new techniques or models can be helpful to manage the water distribution systems (WDS) in a better way. In the present paper, a review is carried out on the existing urban water supply management methodologies with a way forward for the proper management of the water supply systems.",
Arsenic,2345829,"Lysimeter trials to assess the impact of different flood-dry-cycles on the dynamics of pore water concentrations of As, Cr, Mo and V in a contaminated floodplain soil Abstract: hypothesize that the dynamics of water soluble arsenic (As), chromium (Cr), molybdenum (Mo), and vanadium (V) in soils might be controlled by the period of flooding due to changes of redox potential (E-H), pH, and carriers of metals such as dissolved organic carbon (DOC), iron (Fe), manganese (Mn) and sulfate (Sai). Therefore, we aimed to assess the impact of different flood-dry-cycles on the temporal dynamics of pore water concentrations of As, Cr, Mo and V as affected by changes of soil E-H/pH and dynamics of DOC, Fe, Mn and SO42- in a contaminated floodplain soil collected at the Elbe River (Germany). For this purpose a specific groundwater lysimeter technique with two separate lysimeters which served as replicates was used. The groundwater level inside the lysimeters was controlled to simulate different flood-dry-cycles sequentially as follows: the long term (LT) includes 94 days of flooding followed by similar drying term. The short term (ST) comprises 21 days flooding followed by a similar drying term and was repeated six times. The entire experimental period (LT_ST) was about 450 days. The presented data are mean values of both lysimeters. <br> <br>Flooding of the soil caused a significant decrease of EH and pH. Concentrations of soluble As, Cr, Fe, Mn, Mo, and DOC were higher under reducing conditions than under oxidizing conditions in LT. However, As and Cr tended to be mobilized under oxidizing conditions during ST, which might be due to slow kinetics of the redox reaction of As and Cr. Dynamics of Mo were more affected by changes of EH/pH as compared to As, Cr, and V and governed mainly by Fe-Mn chemistry. Concentrations of V in ST were higher than in LT and were controlled particularly by pH and chemistry of Fe. The interactions between the elements and carriers studied were stronger during long flood-dry-cycles than during short cycles, which confirmed our hypothesis. We conclude that the dynamics of As, Cr, Mo, and V are determined by the length of time soils are exposed to flooding, because drivers of element mobility need a certain time to provoke reactions in soils under changing conditions. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,628618,"Arsenite induces DNA-protein crosslinks and cytokeratin expression in the WRL-68 human hepatic cell line Abstract: The induction of DNA-protein crosslinks (DPC) has been proposed as an indicator of early biological effects due to the fact that known or suspected carcinogens induce an increased proportion of proteins tightly bound to DNA. Arsenic, a human carcinogen, is reduced and methylated mainly in liver cells generating a number of intermediate reactive forms which could lead to the formation of DNA-protein crosslinks. The induction of DPC by arsenite [As(III)] was investigated in the WRL-68 human hepatic cell line, testing the possibility that cytokeratins or cytokeratin-like proteins, due to their high content of SH groups, could participate in DPC. The formation and decay of DPC was dose-related. Arsenite was the only intracellular species present since no methylated As forms could be detected. Thus, DPC can be attributed to the presence of arsenite, an important species present in liver during As exposure, whose permanence in the tissue would depend on the methylation rate of the organism. Several cytokeratins were identified by immunoblotting among the proteins crosslinked with DNA, including cytokeratin 18 (CK18), a specific liver intermediate filament. An augmented presence of CK18 was detected in treated cultures by immunoblotting of total protein PAGE. In liver cells cytokeratin synthesis is tightly correlated with differentiation programs, thus arsenite could not only be damaging DNA but also modifying differentiation patterns in this tissue.",1
Arsenic,1936185,Procedia Earth and Plantetary Science Role of colloidal particles as scavengers of groundwater arsenic: a case study from rural Bengal Abstract: ,
Arsenic,1936152,Influence of land use on human bioaccessibility of metals in smelter-impacted soils Abstract: ,
Arsenic,627886,"A trivalent dimethylarsenic compound, dimethylarsine iodide, induces cellular transformation, aneuploidy, centrosome abnormality and multipolar spindle formation in Syrian hamster embryo cells Abstract: The abilities of dimethylarsine iodide (DMI), a model compound of trivalent dimethylarsenicals, to induce cellular transformation, aneuploidy, centrosome abnormality, and multipolar spindle formations were investigated using the Syrian hamster embryo (SHE) cell model. Cellular growth was decreased in a concentration-dependent manner by treatment with DMI at concentrations over 0.1 microM. Treatment with DMI at concentrations from 0.1 to 1.0 microM induced morphological transformation in SHE cells. The transforming activity of DMI, determined by the frequency of morphologically transformed colonies, was approximately 30 times higher than that induced by treatment with the same concentration of sodium arsenite. Flow cytometry suggested an increase in the aneuploid population caused by DMI, as shown by the appearance of hypo-2N, hypo-4N and hypo-8N. DMI also caused abnormal staining of gamma-tubulin, indicating loss of centrosome integrity and a resultant induction of multipolar spindles in mitotic cells. Mitotic cells with centrosomes that coalesced partly at the cell periphery, not the cell center, were detected as early changes that resulted in multipolar spindles. These findings indicate that DMI has transforming activity in SHE cells. Moreover, the results suggest the importance of centrosome abnormalities as a causal change of DMI-induced aneuploidy.",
Arsenic,1337304,"Characterization of boron tolerant bacteria isolated from a fly ash dumping site for bacterial boron remediation Abstract: Boron is an essential micronutrient for plants, but can above certain concentrations be toxic to living organisms. A major environmental concern is the removal of boron from contaminated water and fly ash. For this purpose, the samples were collected from a fly ash dumping site, Nagasaki prefecture, Japan. The chemical characteristics and heavy metal concentration of the samples were performed by X-ray fluorescent analysis and leaching test. For bacterial analysis, samples were collected in sterile plastic sheets and isolation was carried out by serial dilution method. The boron tolerant isolates that showed values of maximum inhibitory concentration toward boron ranging from 100 to 260 mM level were screened. Based on 16S rRNA sequencing and phylogenetic analysis, the isolates were most closely related to the genera Bacillus, Lysinibacillus, Microbacterium and Ralstonia. The boron tolerance of these strains was also associated with resistant to several heavy metals, such as As (III), Cr (VI), Cd, Cu, Pb, Ni, Se (III) and Zn. Indeed, these strains were arsenic oxidizing bacteria confirmed by silver nitrate test. These strains exhibited their salt resistances ranging from 4 to 15 % were determined in Trypticase soy agar medium. The boron tolerant strains were capable of removing 0.1-2.0 and 2.7-3.7 mg l(-1) boron from the medium and fly ash at 168 h. Thus, we have successfully identified the boron tolerant and removal bacteria from a fly ash dumping site for boron remediation.",
Arsenic,1936131,"Effectiveness of amendments to restore metal-arsenic-polluted soil functions using Lactuca sativa L. bioassays Abstract: Purpose: Because the success of the stabilisation of contaminants from amendments depends on the pollutants involved and the amendments used, the goals of this study were to assess whether selected amendments are able to restore highly polluted soils and to advance the knowledge of both the most suitable amendments to restore polluted soils and the most appropriate bioassays to estimate soil toxicity. Materials and methods: An acidic and polluted soil from mining waste was amended with marble sludge, compost and iron in nine different combinations. The soils were placed in plastic pots and bioassays, including the different stages in the development of lettuce (Lactuca sativa L.), were carried out. Pore water was analysed at the different stages of the development of lettuce. At the end of the experiment, pollutant concentrations in lettuce leaf were analysed and the sequential extraction of trace elements was performed. Results and discussion: The effectiveness of the amendments in reducing the toxicity of contaminated soils varied depending on the bioassay used. Marble sludge was the most effective in increasing pH and in reducing pollutant concentrations in pore water, clearly encouraging germination, root elongation and emergence. Throughout the emergence phase, marble sludge decreased in its effectiveness, probably because the pollutants precipitated as hydroxides and carbonates were taken up by the lettuce. In contrast, the compost began to improve the elongation of the seedling and the growth of lettuce. Although the amendments were effective in reducing the negative impact of pollutants in soils, none of them was able to successfully restore the functions of highly polluted soil. Conclusions: The development of the plant until the end of the establishment phase is the best index to estimate soil phytotoxicity, although the effect on the health of potential consumers can only be evaluated from the toxic element concentrations in the plant. The uptake of pollutants stabilised by the amendments would explain why the reduction of easily available pollutant concentrations does not necessarily imply the restoration of the normal functioning of the ecosystem.",
Arsenic,2149098,"Formation of diphenylthioarsinic acid from diphenylarsinic acid under anaerobic sulfate-reducing soil conditions Abstract: Diphenylarsinic acid (DPAA) is a toxic phenylarsenical compound often found around sites contaminated with phenylarsenic chemical warfare agents, diphenylcyanoarsine or diphenylchloroarsine, which were buried in soil after the World Wars. This research concerns the elucidation of the chemical structure of an arsenic metabolite transformed from DPAA under anaerobic sulfate-reducing soil conditions. In LC/ICP-MS analysis, the retention time of the metabolite was identical to that of a major phenylarsenical compound synthesized by chemical reaction of DPAA and hydrogen sulfide. Moreover the mass spectra for the two compounds measured using LC/TOF-MS were similar. Subsequent high resolution mass spectral analysis indicated that two major ions at m/z 261 and 279, observed on both mass spectra, were attributable to C12H10AsS and C12H12AsSO, respectively. These findings strongly suggest that the latter ion is the molecular-related ion ([M+H](+)) of diphenylthioarsinic acid (DPTA; (C6H5)2AsS(OH)) and the former ion is its dehydrated fragment. Thus, our results reveal that DPAA can be transformed to DPTA, as a major metabolite, under sulfate-reducing soil conditions. Moreover, formation of diphenyldithioarsinic acid and subsequent dimerization were predicted by the chemical reaction analysis of DPAA with hydrogen sulfide. This is the first report to elucidate the occurrence of DPAA-thionation in an anaerobic soil.",
Arsenic,1342419,"Junin virus infection impairs stress-granule formation in Vero cells treated with arsenite via inhibition of eIF2? phosphorylation Abstract: Stress granules (SGs) are ephemeral cytoplasmic aggregates containing stalled translation preinitiation complexes involved in mRNA storage and triage during the cellular stress response. SG formation is triggered by the phosphorylation of the alpha subunit of eIF2 (eIF2?), which provokes a dramatic blockage of protein translation. Our results demonstrate that acute infection of Vero cells with the arenavirus Junín (JUNV), aetiological agent of Argentine haemorrhagic fever, does not induce the formation of SGs. Moreover, JUNV negatively modulates SG formation in infected cells stressed with arsenite, and this inhibition correlates with low levels of eIF2? phosphorylation. Transient expression of JUNV nucleoprotein (N) or the glycoprotein precursor (GPC), but not of the matrix protein (Z), inhibits SG formation in a similar manner, comparable to infectious virus. Expression of N and GPC also impaired eIF2? phosphorylation triggered by arsenite. A moderate inhibition of SG formation was also observed when DTT and thapsigargin were employed as stress inducers. In contrast, no inhibition was observed when infected cells were treated with hippuristanol, a translational inhibitor and inducer of SGs that bypasses the requirement for eIF2? phosphorylation. Finally, we analysed SG formation in persistently JUNV-infected cells, where N and GPC are virtually absent and truncated N products are expressed abundantly. We found that persistently infected cells show a quite normal response to arsenite, with SG formation comparable to that of uninfected cells. This suggests that the presence of GPC and/or N is crucial to control the stress response upon JUNV infection of Vero cells.",
Arsenic,1016087,"Sustainable use of arsenic-removing sand filters in Vietnam: psychological and social factors Abstract: Elevated arsenic concentrations in drinking water pose a health threat to millions of people. Although point-of-use sand filters provide an effective technical solution for mitigating arsenic exposure, the actual reduction in health risk also depends on psychological factors that influence behaviors related to this device. For example, acquiring a sand filter must be preferred to competing options for investing effort and money and, once installed, the users must regularly maintain the filters. These key behaviors of sustainable use are related to psychological factors, such as problem awareness, benefits and costs, social and affective influences, and the perception of practical difficulties. This study investigated the sustainable use of arsenic-removing sand filters in Vietnam. Based on questionnaire surveys, data were gathered in 319 rural households and analyzed with regression models. Psychological factors explained significant variance in the investigated key behaviors. Significant factors included perceived improvements in water healthiness and taste, monetary costs, social norms, and affective influences. In questions with open answers, interviewees mentioned various practical problems, particularly those related to the inflexibility of the device and the effort of changing the sand. Interestingly, many interviewees operate the sand filters for removing iron from the water but are unaware of problems with arsenic.",
Arsenic,1025171,"Membrane fatty acids adaptive profile in the simultaneous presence of arsenic and toluene in Bacillus sp. ORAs2 and Pseudomonas sp. ORAs5 strains Abstract: Bacillus sp. ORAs2 and Pseudomonas sp. ORAs5, two arsenic-resistant bacterial strains previously isolated from sediments of the Orbetello Lagoon, Italy, were tested for their adaptation to mixed contaminants on the level of membrane fatty acid composition. The two bacterial strains were characterized by high levels of arsenic resistance, and Pseudomonas sp. ORAs5 was also shown to be solvent-tolerant. The bacterial strains were exposed to mixtures of two toxic compounds: arsenic at fixed concentrations and toluene in variable amounts or, alternatively, toluene at constant values along with arsenic added at variable concentrations. Both strains react to the contaminants by changing the composition of their membrane fatty acids. Bacillus sp. strain ORAs2 showed a correlation between growth rate decreases and fatty acids degree of saturation increases in both cases, although pointedly in the presence of 1, 2, and 3 mM of toluene and different additions of arsenic, counteracting membranes fluidity induced by toxic compounds. In Pseudomonas sp. ORAs5, adaptive changes in membrane composition was observed both in terms of increases in the degree of saturation and in the trans/cis ratio of unsaturated fatty acids in the presence of varying toluene and constant arsenic concentrations, whereas only minor changes occurred with increasing arsenic and constant toluene concentrations. Thus, on the level of membrane composition, Bacillus sp. ORAs2 showed a higher potential for adaptation to the presence of mixed pollutants, suggesting its probable suitability for bioremediation purposes.",
Arsenic,656934,"A significantly joint effect between arsenic and occupational exposures and risk genotypes/diplotypes of CYP2E1, GSTO1 and GSTO2 on risk of urothelial carcinoma Abstract: Cigarette smoking, arsenic and occupational exposures are well-known risk factors for the development of urothelial carcinoma (UC). Therefore, the aim of this study is to investigate whether the effect of cigarette smoking, alcohol consumption, arsenic and occupational exposures on risk of UC could be modified by genetic polymorphisms or cytochrome P450 2E1 and glutathione S-transferase omega. A hospital-based case-control study consisted of 520 histologically confirmed UC cases, and 520 age- and gender-matched cancer-free controls were carried out from September 1998 to December 2007. Genotyping of CYP2E1, GSTO1 and GSTO2 was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Subjects with both of cigarette smoking and alcohol consumption have a significantly increased UC risk (odds ratio [OR]=2.9; 95% confidence interval [CI]=1.9-4.4). Significantly increased UC risks of 1.5 and 1.9 were found for study subjects with high arsenic exposure and those who have been exposed to two or more occupational exposures, respectively. A significantly increased UC risk of 3.9 was observed in study subjects with H2-H2 diplotype of GSTO1 and GSTO2. The significantly highest UC risk of 9.0 was found for those with all environmental risk factors of cigarette smoking, alcohol consumption, arsenic and occupational exposures and two or more risk genotypes/diplotypes of CYP2E1, GSTO1 and GSTO2. Our findings suggest that a significantly joint effect of cigarette smoking, alcohol consumption, arsenic and occupational exposures and risk genotypes/diplotypes of CYP2E1, GSTO1 and GSTO2 on risk of UC was found. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,1017529,"Altered uptake and biological half-lives of 65Zn on arsenic exposure--modulation by zinc treatment Abstract: The present study revealed the effects of zinc on the biokinetics of (65)Zn in rats following arsenic intoxication. The animals were segregated into four groups: group I--untreated controls, group II--arsenic treated (100 ppm as NaAsO(2) in drinking water), group III--zinc treated (227 mg ZnSO(4) per liter drinking water), and group IV--arsenic?+?zinc treated. Each rat was injected intraperitoneally with 1.85 MBq radioactivity of (65)Zn following 3 months of different treatments, and the radioactivity was determined using a suitably shielded scintillation counter. Arsenic treatment showed a significant increase in the fast component (Tb(1)) of the biological half-life of (65)Zn in liver, which remained unaltered in the whole body. Furthermore, arsenic treatment decreased significantly the slow component (Tb(2)) in the whole body, which remained unchanged in the liver. However, zinc supplementation to arsenic-treated rats normalized Tb(1) in the liver, but caused no change in Tb(2) in the whole body. Furthermore, the uptake values of (65)Zn were significantly increased in the liver, brain, kidney, and intestine following arsenic treatment, and the values in the liver and brain were decreased by zinc. Hence, zinc plays a significant role in regulating the biokinetics of (65)Zn in the liver and the whole body of arsenic-intoxicated rats.",
Arsenic,627864,"Significance of intracellular arsenic trioxide for therapeutic response in acute promyelocytic leukemia Abstract: Arsenic trioxide (As2O3) is an effective drug for treatment of acute promyelocytic leukemia (APL) and malignant tumors. However, it is not commonly known to researchers that sensitivity has been associated with As2O3 concentration in target cells. Cell lines and cell strains of leukemia and solid cancer cells were treated with different concentrations of As2O3, and the concentrations were compared to apoptosis detected by FITC-annexin V and propidium iodide (PI) double staining. Results showed that intracellular and intercellular concentrations of arsenic in different cell lines differed. Our study noted that the cell lines had concentrations of arsenic trioxide in decreasing order, as follows: APL primary cell > K562 > CML primary cell > HL-60 > AML-M2 primary cell > HeLa > H-22. Higher intracellular As2O3 concentrations in cell lines APL, NB4, and K562 can be obtained by treating in culture medium with lower As2O3 concentration for longer times than the transient higher concentration. These results indicate that different leukemia and solid carcinoma cell lines have different intracellular arsenic concentrations, which correlate with different sensitivities to As2O3 in clinical treatment. The intracellular As2O3 concentration is higher; in addition, we note apoptosis, a very important observation in our study. As2O3 inhibited the growth of these cell lines significantly. Novel techniques by maintaining continuous low but effective arsenic levels inside the target leukemic cells in APL may improve the complete remission rate and overall survival with minimum cost and drug toxicity. Copyright 2005 Wiley-Liss, Inc.",
Arsenic,1022163,"Ascorbic acid and alpha-tocopherol as potent modulators on arsenic induced toxicity in mitochondria Abstract: Arsenic exists ubiquitously in our environment and various forms of arsenic circulate in air, water, soil and living organisms. Since arsenic compounds have shown to exert their toxicity chiefly by generating reactive oxygen species, we have evaluated the effect of antioxidants ascorbic acid and alpha-tocopherol on lipid peroxidation, antioxidants and mitochondrial enzymes in liver and kidney of arsenic exposed rats. A significant increase in the level of lipid peroxidation and decrease in the levels of antioxidants and in the activities of mitochondrial enzymes were observed in arsenic intoxicated rats. Co-administration of arsenic treated rats with ascorbic acid and alpha-tocopherol showed significant reduction in the level of lipid peroxidation and elevation in the levels of ascorbic acid, alpha-tocopherol, glutathione and total sulfhydryls and in the activities of isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, NADH-dehydrogenase and cytochrome c oxidase. From our results, we conclude that ascorbic acid and alpha-tocopherol alleviate arsenic- induced alterations in mitochondria.",
Arsenic,1020019,"Very low concentrations of arsenite suppress poly(ADP-ribosyl)ation in mammalian cells Abstract: Arsenite is a naturally occurring environmental pollutant of major concern, since adverse health effects including cancer of skin and internal organs have been attributed to chronic arsenic exposure especially via drinking water. Arsenite is not a significant inducer of point mutations but exerts clastogenic activities and interferes with various DNA repair systems at concentrations in the low micromolar range. Nevertheless, no single DNA repair protein exquisitely sensitive to arsenic has been identified. Here we report that poly(ADP-ribosyl)ation, which is predominantly mediated by poly(ADP-ribose) polymerase-1 (PARP-1), is inhibited at concentrations as low as 10 nM in cultured HeLa cells, closely matching arsenic concentrations in blood and urine of the general population. Since poly(ADP-ribosyl)ation is an immediate cellular response to DNA damage, playing a major role in DNA base excision repair and the maintenance of genomic stability, its inhibition by arsenite may add to the risk of cancer formation under low-exposure conditions.",
Arsenic,1379244,"Attenuation of insulin actions in primary rat hepatocyte cultures by phenylarsine oxide Abstract: Phenylarsine oxide (PAO), a trivalent arsenical which complexes vicinal dithiols, prevented the action of insulin in primary cultured adult rat hepatocytes. Simultaneous short-term treatment of 48-h old cells with insulin and 2 microM PAO resulted in complete attenuation of the insulin-dependent increase in the level of fructose 2,6-bisphosphate and the activation of phosphofructokinase 2, pyruvate kinase, glucokinase flux and glycolysis. Basal rates of glucose transport and glycolysis were not affected. PAO also abolished stimulation of glycogen synthesis and amino-acid transport and the decrease of glycogenolysis evoked by insulin. The 20-fold activation of the insulin receptor tyrosine kinase by insulin was, however, not reduced by PAO. The data suggest that in differentiated hepatocytes insulin signal transduction involves vicinal sulhydryls located at a post-receptor step.",
Arsenic,2088494,"High mobilization of arsenic, metals and rare earth elements in seepage waters driven by respiration of old allochthonous organic carbon Abstract: Metal and metalloid mobilization processes within seepage water are of major concern in a range of water reservoir systems. The mobilization process of arsenic and heavy metals within a dam and sediments of a drinking water reservoir was investigated. Principle component analysis (PCA) on time series data of seepage water showed a clear positive correlation of arsenic with iron and DOC (dissolved organic carbon), and a negative correlation with nitrate due to respiratory processes. A relationship of reductive metal and metalloid mobilization with respiration of old carbon was shown. The system is influenced by sediment layers as well as a recent DOC input from degraded ombrotrophic peatbogs in the catchment area. The isotopic composition ((12)C, (13)C and (14)C) of DOC is altered along the path from basin to seepage water, but no significant changes in structural parameters (LC-OCD-OND, FT-IR) could be seen. DIC (dissolved inorganic carbon) in seepage water partly originates from respiratory processes, and a higher relationship of it with sediment carbon than with the DOC inventory of infiltrating water was found. This study revealed the interaction of respiratory processes with metal and metalloid mobilization in sediment water flows. In contrast to the presumption that emerging DOC via respiratory processes mainly controls arsenic and metal mobilization it could be shown that the presence of aged carbon compounds is essential. The findings emphasize the importance of aged organic carbon for DOC, DIC, arsenic and metal turnover.",
Arsenic,1350817,"SIMULTANEOUS DETERMINATION OF GERMANIUM, ARSENIC AND SOME OTHER TRACE-ELEMENTS IN BIOLOGICAL REFERENCE MATERIALS BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY Abstract: ",
Arsenic,1579384,"Arsenate adsorption on three types of granular schwertmannite Abstract: Schwertmannite was synthesized on a 2 m(3)-scale and fabricated to irregular, cylindrical and spherical shape granules using drum granulation, extrusion and spray coating, respectively. The granules were systematically evaluated for As(V) removal from drinking water in terms of both performance and safety. The irregular and cylindrical shape granules (IS and CS) had larger schwertmannite loadings, higher porosity, more abundant pore structure and larger micropore volumes than those with a spherical shape (SS). As(V) adsorption kinetics on IS, CS and SS schwertmannite granules followed a pseudo-second order rate equation and two-stages of intraparticle diffusion. The rate parameters were in an order of IS &gt; CS &gt; SS granules. The faster uptake kinetics of the IS granules was due to their largest pore volume and interparticle porosity. Furthermore, adsorption capacities of 34, 21 and 5 mg/g, for IS, CS and SS granular schwertmannite samples were achieved at an initial As(V) concentration of 20 mg/L and adsorbent dose of 0.5 g/L. IS and CS samples performed much better over a wide pH range versus SS samples. Except for humic acid, PO4(3-) and SiO4(4-) did not inhibit As(V) adsorption on IS and CS granular specimens. SS samples worked poorly even in the absence or presence of co-existing anions. Regeneration was achieved using 0.1 M NaOH. The recycled IS and CS granular specimens can be used for 4 different cycles with no or nominal loss of adsorption capacity. Column experiments were also conducted. The IS, CS and SS granular specimens treated 8100, 4200 and 120 bed volumes (BVs) of contaminated water. No heavy metals leached from the packed granular adsorbent and appeared in the column effluent. Furthermore, the toxicity characteristic leaching procedure (TCLP) showed that the spent IS and CS granules were inert and could safely be disposed of in landfills. In short, irregular-shaped granules (IS) fabricated by drum granulation is a good candidate for arsenic removal from drinking water with a high future application potential.",
Arsenic,1355630,"Induction of c-anaphase and diplochromosome through dysregulation of spindle assembly checkpoint by sodium arsenite in human fibroblasts Abstract: Cytogenetic alterations induced by arsenite are associated with its carcinogenic activity. Cytogenetic analysis revealed first that arsenite induced c-anaphases in a time- and dose-dependent manner in human fibroblasts (HFW). With additional incubation of arsenite-arrested mitotic cells in drug-free medium for 0-48 h, approximately 35% exited from mitosis without cell division. This was confirmed by the appearance of tetraploid metaphase, mainly diplochromosomes, in the subsequent cell division. Treatment of HFW cells with both nocodazole, a known agent of microtubular depolymerization, and Taxol, which induces tubulin polymerization and inhibits disassembly of microtubules, resulted in remarkable mitotic arrest but induced only negligible c-anaphase, tetraploidy, and diplochromosomes. Staurosporine, a kinase inhibitor that could effectively reduce arsenite-induced c-anaphase, could also decrease the development of diplochromosomes in the subsequent cell division cycle. These results imply that arsenite-induced c-anaphases mainly exited from mitosis without cell division and became tetraploid in the subsequent cell cycle. Antitubulin immunofluorescent staining confirmed no formation of bipolar spindles in nocodazole-arrested mitotic HFW cells, whereas in arsenite-arrested mitotic cells bipolar spindles were present but distorted in appearance and apparently dysfunctional. Mitotic arrest deficient 2 (Mad2) signal was, as expected, clearly visible at centromeres of nocodazole-arrested mitotic cells. However, the Mad2 signal at centrosomes became insignificant in either arsenite-arrested or nocodazole/arsenite-arrested mitotic cells. In addition, the association of Mad2 with the APC/C(cdc20) complex and the accumulation of Pds1, an anaphase inhibitor, were remarkably reduced in arsenite-arrested mitotic cells as compared with nocodazole-arrested mitotic cells. These results support the observation that nocodazole can inhibit spindle formation and, hence, activate spindle assembly checkpoint to arrest cells at metaphase. In contrast, the dysfunctional bipolar spindles in arsenite-arrested mitotic cells could not effectively activate spindle assembly checkpoint and, hence, resulted in formation of c-anaphase and diplochromosomes in the subsequent cell division.",
Arsenic,1255532,"The role of drinking water sources, consumption of vegetables and seafood in relation to blood arsenic concentrations of Jamaican children with and without Autism Spectrum Disorders Abstract: Arsenic is a toxic metal with harmful effects on human health, particularly on cognitive function. Autism Spectrum Disorders (ASDs) are lifelong neurodevelopmental and behavioral disorders manifesting in infancy or early childhood. We used data from 130 children between 2 and 8years (65 pairs of ASD cases with age- and sex-matched control), to compare the mean total blood arsenic concentrations in children with and without ASDs in Kingston, Jamaica. Based on univariable analysis, we observed a significant difference between ASD cases and controls (4.03?g/L for cases vs. 4.48?g/L for controls, P&lt;0.01). In the final multivariable General Linear Model (GLM), after controlling for car ownership, maternal age, parental education levels, source of drinking water, consumption of &quot;yam, sweet potato, or dasheen&quot;, &quot;carrot or pumpkin&quot;, &quot;callaloo, broccoli, or pak choi&quot;, cabbage, avocado, and the frequency of seafood consumption per week, we did not find a significant association between blood arsenic concentrations and ASD status (4.36?g/L for cases vs. 4.65?g/L for controls, P=0.23). Likewise, in a separate final multivariable GLM, we found that source of drinking water, eating avocado, and eating &quot;callaloo, broccoli, or pak choi&quot; was significantly associated with higher blood arsenic concentrations (all three P&lt;0.05). Based on our findings, we recommend assessment of arsenic levels in water, fruits, and vegetables, as well as increased awareness among the Jamaican population regarding potential risks for various exposures to arsenic.",
Arsenic,2064231,"Selective hydride generation- cryotrapping- ICP-MS for arsenic speciation analysis at picogram levels: Analysis of river and sea water reference materials and human bladder epithelial cells Abstract: An ultra sensitive method for arsenic (As) speciation analysis based on selective hydride generation (HG) with preconcentration by cryotrapping (CT) and inductively coupled plasma- mass spectrometry (ICP-MS) detection is presented. Determination of valence of the As species is performed by selective HG without prereduction (trivalent species only) or with L-cysteine prereduction (sum of tri- and pentavalent species). Methylated species are resolved on the basis of thermal desorption of formed methyl substituted arsines after collection at -196°C. Limits of detection of 3.4, 0.04, 0.14 and 0.10 pg mL(-1) (ppt) were achieved for inorganic As, mono-, di- and trimethylated species, respectively, from a 500 ?L sample. Speciation analysis of river water (NRC SLRS-4 and SLRS-5) and sea water (NRC CASS-4, CASS-5 and NASS-5) reference materials certified to contain 0.4 to 1.3 ng mL(-1) total As was performed. The concentrations of methylated As species in tens of pg mL(-1) range obtained by HG-CT-ICP-MS systems in three laboratories were in excellent agreement and compared well with results of HG-CT-atomic absorption spectrometry and anion exchange liquid chromatography- ICP-MS; sums of detected species agreed well with the certified total As content. HG-CT-ICP-MS method was successfully used for analysis of microsamples of exfoliated bladder epithelial cells isolated from human urine. Here, samples of lysates of 25 to 550 thousand cells contained typically tens pg up to ng of iAs species and from single to hundreds pg of methylated species, well within detection power of the presented method. A significant portion of As in the cells was found in the form of the highly toxic trivalent species.",
Arsenic,628470,"Inhibition of insulin-dependent glucose uptake by trivalent arsenicals: Possible mechanism of arsenic-induced diabetes Abstract: Chronic exposures to inorganic arsenic (iAs) have been associated with increased incidence of noninsulin (type-2)-dependent diabetes mellitus. Although mechanisms by which iAs induces diabetes have not been identified, the clinical symptoms of the disease indicate that iAs or its metabolites interfere with insulin-stimulated signal transduction pathway or with critical steps in glucose metabolism. We have examined effects of iAs and methylated arsenicals that contain trivalent or pentavalent arsenic on glucose uptake by 3T3-L1 adipocytes. Treatment with inorganic and methylated pentavalent arsenicals (up to 1 mM) had little or no effect on either basal or insulin-stimulated glucose uptake. In contrast, trivalent arsenicals, arsenite (iAs(III)), methylarsine oxide (MAs(III)O), and iododimethylarsine (DMAs(III)O) inhibited insulin-stimulated glucose uptake in a concentration-dependent manner. Subtoxic concentrations of iAs(III) (20 microM), MAs(III)O (1 microM), or DMAs(III)I (2 microM) decreased insulin-stimulated glucose uptake by 35-45%. Basal glucose uptake was significantly inhibited only by cytotoxic concentrations of iAs(III) or MAs(III)O. Examination of the components of the insulin-stimulated signal transduction pathway showed that all trivalent arsenicals suppressed expression and possibly phosphorylation of protein kinase B (PKB/Akt). The concentration of an insulin-responsive glucose transporter (GLUT4) was significantly lower in the membrane region of 3T3-L1 adipocytes treated with trivalent arsenicals as compared with untreated cells. These results suggest that trivalent arsenicals inhibit insulin-stimulated glucose uptake by interfering with the PKB/Akt-dependent mobilization of GLUT4 transporters in adipocytes. This mechanism may be, in part, responsible for the development of type-2 diabetes in individuals chronically exposed to iAs.",
Arsenic,2088603,"Which nerve conduction parameters can predict spontaneous electromyographic activity in carpal tunnel syndrome? Abstract: <strong>OBJECTIVE: </strong>We investigate electrodiagnostic markers to determine which parameters are the best predictors of spontaneous electromyographic (EMG) activity in carpal tunnel syndrome (CTS).<br /><br /><strong>METHODS: </strong>We enrolled 229 patients with clinically proven and nerve conduction study (NCS)-proven CTS, as well as 100 normal control subjects. All subjects were evaluated using electrodiagnostic techniques, including median distal sensory latencies (DSLs), sensory nerve action potentials (SNAPs), distal motor latencies (DMLs), compound muscle action potentials (CMAPs), forearm median nerve conduction velocities (FMCVs) and wrist-palm motor conduction velocities (W-P MCVs). All CTS patients underwent EMG examination of the abductor pollicis brevis (APB) muscle, and the presence or absence of spontaneous EMG activities was recorded. Normal limits were determined by calculating the means±2 standard deviations from the control data. Associations between parameters from the NCS and EMG findings were investigated.<br /><br /><strong>RESULTS: </strong>In patients with clinically diagnosed CTS, abnormal median CMAP amplitudes were the best predictors of spontaneous activity during EMG examination (p&lt;0.001; OR 36.58; 95% CI 15.85-84.43). If the median CMAP amplitude was ?2.1mV, the rate of occurrence of spontaneous EMG activity was &gt;95% (positive predictive rate &gt;95%). If the median CMAP amplitude was higher than the normal limit (&gt;4.9mV), the rate of no spontaneous EMG activity was &gt;94% (negative predictive rate &gt;94%). An abnormal SNAP amplitude was the second best predictor of spontaneous EMG activity (p&lt;0.001; OR 4.13; 95% CI 2.16-7.90), and an abnormal FMCV was the third best predictor (p=0.01; OR 2.10; 95% CI 1.20-3.67). No other nerve conduction parameters had significant power to predict spontaneous activity upon EMG examination.<br /><br /><strong>CONCLUSIONS: </strong>The CMAP amplitudes of the APB are the most powerful predictors of the occurrence of spontaneous EMG activity. Low CMAP amplitudes are strongly associated with spontaneous activity, whereas high CMAP amplitude are less associated with spontaneous activity, implying that needle EMG examination should be recommended for the detection of spontaneous activity in those CTS patients whose NCS reveals CMAP amplitudes between 2.1mV and the lower normal limit (4.9mV in the present study).<br /><br /><strong>SIGNIFICANCE: </strong>Using NCS, electromyographers can predict the presence of spontaneous EMG activity in CTS patients.",
Arsenic,62136,"Arsenic in the drinking water of the city of Antofagasta: Epidemiological and clinical study before and after the installation of a treatment plant Abstract: This is a second report of epidemiological and clinical investigation, related to the arsenic health problem, unique in the world, occurring in the city of Antofagasta, Chile. The arsenic problem originates in the chronic contamination of water supply in the city during 12 years. This phenomena, investigated clinically and epidemiologically and first reported in 1971, prompted the installation of a water treatment plant. This report aims to evaluate the working efficiency of the plant. The study was carried out through the examination of arsenic content in hair and nail clipping samples of the inhabitants of Antofagasta and the determination of this element in cultivated vegetables and carbonated beverages. Also a clinical study in school children, looking for cutaneous lesions attributed to arsenicism, was made. Results are encouraging. They reveal that contamination persists but in significantly lower levels.",
Arsenic,1058799,"Speciation of arsenic in airborne particulate matter Abstract: Airborne particulate matter from the atmosphere of the city of Isfahan was collected on quartz fiber filters. The exposed filters were digested with a mixture of H sub(2)SO sub(4) and HNO sub(3) 1:2 (v/v). The determination of different species of arsenic was carried-out by hydride-generation atomic absorption spectrometryI. It was found that more than 50% of total atmospheric exists as As(III), A correlation was found. Several samples from diesel engine particulate matter were analyzed, and a considerable amount of arsenic was found in them.",
Arsenic,1763306,Preliminary assessment of metal concentrations in drinking water in the city of Szczecin (Poland): human health aspects Abstract: ,
Arsenic,1341474,"Sodium arsenite and cadmium chloride induction of proteasomal inhibition and HSP accumulation in Xenopus laevis A6 kidney epithelial cells Abstract: Sodium arsenite (NA) and cadmium chloride (CdCl2) are relatively abundant environmental toxicants that have multiple toxic effects including carcinogenesis, dysfunction of gene regulation and DNA and protein damage. In the present study, treatment of Xenopus laevis A6 kidney epithelial cells with concentrations of NA (20-30 ?M) or CdCl2 (100-200 ?M) that induced HSP30 and HSP70 accumulation also produced an increase in the relative levels of ubiquitinated protein. Actin protein levels were unchanged in these experiments. In time course experiments, the levels of ubiquitinated protein and HSPs increased over a 24 h exposure to NA or CdCl2. Furthermore, treatment of cells with NA or CdCl2 reduced the relative levels of proteasome chymotrypsin (CT)-like activity compared to control. Interestingly, pretreatment of cells with the HSP accumulation inhibitor, KNK437, prior to NA or CdCl2 exposure decreased the relative levels of ubiquitinated protein as well as HSP30 and HSP70. A similar finding was made with ubiquitinated protein induced by proteasomal inhibitors, MG132 and celastrol, known to induce HSP accumulation in A6 cells. However, the NA- or CdCl2-induced decrease in proteasome CT-like activity was not altered by KNK437 pretreatment. This study has shown for the first time in poikilothermic vertebrates that NA and CdCl2 can inhibit proteasomal activity and that there is a possible association between HSP accumulation and the mechanism of protein ubiquitination.",
Arsenic,1032941,"Whole-body arsenic concentrations in rainbow trout during acute exposure to arsenate Abstract: This research explored the influence of temperature and waterborne arsenate exposure level on the whole-body arsenic (As) concentration in rainbow trout (Oncorhynchus mykiss) at loss of equilibrium (LOE), an acute toxicity endpoint. The mean median times (ET50s) to LOE for fish exposed to 120 mg arsenate liter-1 at 5 degrees C, as well as 60 and 120 mg liter-1 at 15 degrees C were 56.8, 210, and 34.8 hr, respectively. Despite the differences in ET50, the fish showed respective mean (SE) whole-body As concentrations of 8.6 (0.3), 8.1 (0.6), and 8.6 (0.4) micrograms As g-1, values which were not significantly different. Fish exposed to 240 mg arsenate liter-1 at 5 degrees C, which had a LOE ET50 of 32.2 hr, were observed to have a mean (SE) whole-body arsenic concentration of 13.5 micrograms g-1, significantly higher than the levels in fish from all other treatments. A 3-hr delay between LOE and sampling did not significantly alter whole-body As concentration. The results are discussed in terms of the utility of using whole-body As concentrations to interpret the impacts of arsenate on fish populations in the field.",
Arsenic,628365,"Arsenite induces prominent mitotic arrest via inhibition of G2 checkpoint activation in CGL-2 cells Abstract: Arsenic compounds, which are well-documented human carcinogens, are now used in cancer therapy. Knowledge of the mechanism by which arsenic exerts its toxicity may help in designing a more effective regimen for therapy. In this study, we showed that arsenite could induce prominent mitotic arrest in CGL-2 cells and demonstrated the presence of damaged DNA in arsenite-arrested mitotic cells. We then explored why these cells with arsenite-induced DNA damage were arrested at mitosis instead of G2 stage. When synchronized CGL-2 cells were treated with arsenite at stage G1, S or G2, all progressed into, and arrested at, the mitotic stage and contained damaged DNA, as demonstrated by the appearance of the DNA double-strand break marker, phosphorylated histone H2A.X (gamma-H2AX). Since X-irradiation induced G2 arrest in CGL-2 cells, these cells clearly have a functional G2 DNA damage checkpoint. However, treatment of X-irradiated CGL-2 cells with arsenite resulted in a decrease in G2 cells and an increase in mitotic cells, suggesting that arsenite may inhibit activation of the G2 DNA damage checkpoint and thus allow cells with damaged DNA to proceed from G2 into mitosis. Immunoblot analysis confirmed that arsenite treatment reduced the X-irradiation-induced phosphorylation of both ataxia-telangiectasia, mutated at serine 1981 and Cdc25C at serine 216, events which are crucial for G2 checkpoint activation and G2 arrest. Moreover, a higher frequency of apoptotic cells is observed in mitotic CGL-2 cells arrested by arsenite than those arrested by nocodazole or taxol. Our results show that the combined effects of arsenite in inducing DNA damages, inhibiting the activation of G2 checkpoint, and arresting cells with damaged DNA in the mitotic stage may subsequently enhance the induction of apoptosis in arsenite-arrested mitotic CGL-2 cells.",
Arsenic,628690,"Arsenic induces apoptosis in rat cerebellar neurons via activation of JNK3 and p38 MAP kinases Abstract: Primary cultures of rat cerebellar neurons were used to study mechanisms of arsenic neurotoxicity. Exposure to 5, 10, or 15 microM sodium arsenite reduced cerebellar neuron viability and induced nuclear fragmentation and condensation as well as DNA degradation to oligonucleosome fragments. Exposure to 1 or 5 mM dimethylarsinic acid caused similar changes. Therefore, both inorganic arsenite and organic dimethylarsinic acid induce apoptosis in cerebellar neurons, with the inorganic form being more toxic. Cotreatment with cycloheximide or actinomycin D, inhibitors of protein or RNA synthesis, respectively, or with the caspase inhibitor zVAD, completely blocked arsenite-induced cerebellar neuron apoptosis. This implies that arsenite-induced cerebellar neuron apoptosis requires new gene expression and caspase activation. Interestingly, sodium arsenite selectively activated p38 and JNK3, but not JNK1 or JNK2 in cerebellar neurons. Blocking the p38 or JNK signaling pathways using the inhibitors SB203580 or CEP-1347 protected cerebellar neurons against arsenite-induced apoptosis. These data suggest that arsenite neurotoxicity may be due to apoptosis caused by activation of p38 and JNK3 MAP kinases. Copyright 2001 Academic Press.",
Arsenic,1519167,"Five examples of assessment and expression of measurement uncertainty Abstract: It is a long-accepted tenet of scientific practice that every measurement result ought to include a statement of uncertainty associated with the measured value. Such uncertainty should also be propagated to functions of the measured values. It is also widely recognized that probability distributions are well suited to express measurement uncertainty and that statistical methods are the choice vehicles to produce uncertainty assessments incorporating information in empirical data as well as other relevant information, either about the quantity that is the object of measurement or about the techniques or apparatuses used in measurement. Statistical models and methods of statistical inference provide the technical machinery necessary to evaluate and propagate measurement uncertainty. Some of these models and methods are illustrated in five examples: (i) measurement of the refractive index of a glass prism (employing a venerable formula due to Gauss, as well as contemporary Monte Carlo methods); (ii) measurement of the mass fraction of arsenic in oyster tissue using data from an inter-laboratory study (introducing a Bayesian hierarchical model with adaptive tail heaviness); (iii) measurement of the relative viscosity increment of a solution of sucrose in water (using a copula); (iv) mapping measurements of radioactivity in the area of Fukushima, Japan (via both local regression and kriging, and explaining how model uncertainty may be evaluated); and (v) combining expert opinions about the flow rate of oil during the Deepwater Horizon oil spill into the Gulf of Mexico (via linear or logarithmic pooling).",
Arsenic,627342,"Arsenic species in drinking water, hair, fingernails, and urine of patients with blackfoot disease Abstract: A large number of residents on the southwest coast of Taiwan suffer from an endemic peripheral vascular disease called blackfoot disease. Although the etiology has been investigated since 1958, the cause of blackfoot disease remains unknown. Certain substances contained in artesian well water have been implicated as causal factors, including arsenic as the predominant element. Data in this study demonstrated that in the well water collected from blackfoot disease regions of Taiwan there was a marked increase in total arsenic concentrations, with the predominant species being inorganic arsenical compounds. The concentrations of organic methyl arsenicals were present in minimal amounts. The excretion of total arsenic, inorganic arsenic, monomethylarsonic acid, and trimethylarsenic acid in the urine of patients afflicted with blackfoot disease was significantly higher than for control subjects. Further, in patients with blackfoot disease the concentrations of total arsenic and inorganic arsenic were markedly elevated in the hair and fingernails. Data suggest that blackfoot disease is associated with individuals ingesting well, water contaminated with arsenic primarily in the inorganic form and that hair, fingernails, or urine specimens serve as equally effective biomarkers of exposure. The fact that arsenic intoxication as manifested by blackfoot disease is still prevalent despite the stoppage of well-water consumption for two decades illustrates the persistent nature of arsenic action.",
Arsenic,1355022,Equilibrium and kinetics of adsorption of phosphate onto iron-doped activated carbon Abstract: ,
Arsenic,2064269,"Silibinin potentially attenuates arsenic-induced oxidative stress mediated cardiotoxicity and dyslipidemia in rats Abstract: Cardiac dysfunction is one of the major causes of mortality and morbidity throughout the world. Chronic exposure of arsenic (As) mainly leads to cardiotoxic effect. Cardiotoxicity was induced by the sodium arsenite as the source of As (5 mg/kg BW, PO) for 4 weeks. As intoxication significantly (p &lt; 0.05) increased the serum cardiac markers, viz. creatine kinase-MB, lactate dehydrogenase, aspartate transaminase, alanine transaminase and alkaline phosphatase, oxidative stress markers in heart, plasma total cholesterol (TC), triglycerides (TG), phospholipids (PL), free fatty acids (FFA), low density lipoprotein cholesterol, very low density lipoprotein cholesterol as well as cardiac lipid profile (TC, TG and FFA) and significantly (p &lt; 0.05) decreased the level of serum high density lipoprotein cholesterol, cardiac PL, mitochondrial enzymes such as ICDH, SDH, MDH, ?-KDH and NADH dehydrogenase, levels of enzymatic antioxidant, nonenzymatic antioxidants and membrane-bound ATPases in heart. In addition, As-intoxicated rats showed a significant (p &lt; 0.05) up-regulation of myocardial NADPH (NOX) oxidase sub units such as NOX2 and NOX4 as well as Keap-1 and down-regulation of Nrf2 and HO-1 protein expressions. Pre-administration of silibinin (SB) (75 mg/kg BW) remarkably recovered all these altered parameters to near normalcy in As-induced cardiotoxic rat. Moreover, the light microscopic and transmission electron microscopic study further supports the protective efficacy of SB on the heart mitochondria. In conclusion, our data demonstrate that SB has a potential to extenuate the arsenic-induced cardiotoxicity and dyslipidemia in rat.",
Arsenic,1451169,"Efficient arsenic metabolism--The AS3MT haplotype is associated with DNA methylation and expression of multiple genes around AS3MT Abstract: Arsenic is a very potent toxicant. One major susceptibility factor for arsenic-related toxicity is the efficiency of arsenic metabolism. The efficiency, in turn, is associated with non-coding single nucleotide polymorphisms (SNPs) in the arsenic methyltransferase AS3MT on chromosome 10q24. However, the mechanism of action for these SNPs is not yet clarified. Here, we assessed the influence of genetic variation in AS3MT on DNA methylation and gene expression within 10q24, in people exposed to arsenic in drinking water. DNA was extracted from peripheral blood from women in the Argentinean Andes (N?=?103) and from cord blood from new-borns in Bangladesh (N?=?127). AS3MT SNPs were analyzed with Sequenom or Taqman assays. Whole genome epigenetic analysis with Infinium HumanMethylation450 BeadChip was performed on bisulphite-treated DNA. Whole genome gene expression analysis was performed with Illumina DirectHyb HumanHT-12 v4.0 on RNA from peripheral blood. Arsenic exposure was assessed by HPLC-ICPMS. In the Argentinean women, the major AS3MT haplotype, associated with more efficient arsenic metabolism, showed increased methylation of AS3MT (p?=?10(-6)) and also differential methylation of several other genes within about 800 kilobasepairs: CNNM2 (p<10(-16)), NT5C2 (p<10(-16)), C10orf26 (p?=?10(-8)), USMG5 (p?=?10(-5)), TRIM8 (p?=?10(-4)), and CALHM2 (p?=?0.038) (adjusted for multiple comparisons). Similar, but weaker, associations between AS3MT haplotype and DNA methylation in 10q24 were observed in cord blood (Bangladesh). The haplotype-associated altered CpG methylation was correlated with reduced expression of AS3MT and CNNM2 (r(s)?=?-0.22 to -0.54), and with increased expression of NT5C2 and USMG5 (r(s)?=?0.25 to 0.58). Taking other possibly influential variables into account in multivariable linear models did only to a minor extent alter the strength of the associations. In conclusion, the AS3MT haplotype status strongly predicted DNA methylation and gene expression of AS3MT as well as several genes in 10q24. This raises the possibility that several genes in this region are important for arsenic metabolism.",
Arsenic,1021690,"Movement of Water Infiltrated from a Recharge Basin to Wells Abstract: Local surface water and stormflow were infiltrated intermittently from a 40-ha basin between September 2003 and September 2007 to determine the feasibility of recharging alluvial aquifers pumped for public supply, near Stockton, California. Infiltration of water produced a pressure response that propagated through unconsolidated alluvial-fan deposits to 125 m below land surface (bls) in 5 d and through deeper, more consolidated alluvial deposits to 194 m bls in 25 d, resulting in increased water levels in nearby monitoring wells. The top of the saturated zone near the basin fluctuates seasonally from depths of about 15 to 20 m. Since the start of recharge, water infiltrated from the basin has reached depths as great as 165 m bls. On the basis of sulfur hexafluoride tracer test data, basin water moved downward through the saturated alluvial deposits until reaching more permeable zones about 110 m bls. Once reaching these permeable zones, water moved rapidly to nearby pumping wells at rates as high as 13 m/d. Flow to wells through highly permeable material was confirmed on the basis of flowmeter logging, and simulated numerically using a two-dimensional radial groundwater flow model. Arsenic concentrations increased slightly as a result of recharge from 2 to 6 µg/L immediately below the basin. Although few water-quality issues were identified during sample collection, high groundwater velocities and short travel times to nearby wells may have implications for groundwater management at this and at other sites in heterogeneous alluvial aquifers.",
Arsenic,2347749,"Simultaneous Adsorption of Chromium (VI) and Phosphate by Calcined Mg-Al-CO3 Layered Double Hydroxides Abstract: The adsorption characteristics of chromium (VI) and phosphate on calcined Mg-Al-CO3 layered double hydroxides (CLDH) were investigated in single and binary systems. A series of batch experiments were performed to study the influence of various experimental parameters. In this study, CLDH exhibited a high adsorption capacity for Cr (VI) and P in a single system. The experimental data were close to the theoretical adsorption capacity given by the Langmuir isotherm, the calculating adsorption capacities of Cr (VI) and P were up to 70.42 mg/g and 97.09 mg/g, respectively. It was found that the initial pH was approximately 6 and it took 24 h to reach equilibrium when P and Cr (VI) were added simultaneously. The experimental data were best fitted by a pseudo-second-order kinetics model. Competitive adsorption between Cr (VI) and P existed in the binary system. The presence of Cr (VI) had no significant influence on P adsorption. However, the suppression of Cr (VI) adsorption was obvious when the initial concentration of P was up to 10 mg/L with a concentration of 0.5 g/L of CLDH.",
Arsenic,1597340,"Mid-infrared supercontinuum generation in As2S3-silica ""nano-spike"" step-index waveguide Abstract: Efficient generation of a broad-band mid-infrared supercontinuum spectrum is reported in an arsenic trisulphide waveguide embedded in silica. A chalcogenide ""nano-spike"", designed to transform the incident light adiabatically into the fundamental mode of a 2-mm-long uniform section 1 µm in diameter, is used to achieve high launch efficiencies. The nano-spike is fully encapsulated in a fused silica cladding, protecting it from the environment. Nano-spikes provide a convenient means of launching light into sub-wavelength scale waveguides. Ultrashort (65 fs, repetition rate 100 MHz) pulses at wavelength 2 µm, delivered from a Tm-doped fiber laser, are launched with an efficiency ~12% into the sub-wavelength chalcogenide waveguide. Soliton fission and dispersive wave generation along the uniform section result in spectral broadening out to almost 4 µm for launched energies of only 18 pJ. The spectrum generated will have immediate uses in metrology and infrared spectroscopy.",
Arsenic,744828,"The role of valence and methylation state on the activity of arsenic during mitosis Abstract: Trivalent methylated arsenicals are much more potent DNA damaging agents, clastogens, and large deletion mutagens than are their inorganic and pentavalent counterparts. Previously, we had noticed that many of the arsenicals induced ?c-type? anaphases characteristic of spindle poisons. In the present study, we exposed human lymphoblasts for 6 h to six arsenicals: sodium arsenate (NaAs5), sodium arsenite (NaAs3), monomethylarsonic acid (MMA5), monomethylarsonous acid (MMA3), dimethylarsinic acid (DMA5), and dimethylarsinous acid (DMA3). Slides were then prepared, and the mitotic indices (MI) were calculated. NaAs5 caused a small but significant increase in MI. MMA5 also caused only a slight increase in MI that just reached statistical significance. In contrast, DMA5 caused a highly significant increase in MI producing ~75% the MI of demecolcine, the positive control. NaAs3 had no significant effect on MI and was quite toxic. MMA3 induced more than a twofold increase in MI compared to the control. DMA3 gave inconsistent results. We also exposed each arsenical directly to tubulin and spectrophotometrically measured the effect on polymerization. None of the pentavalent arsenicals had a substantial effect on polymerization of tubulin. In contrast, NaAs3 inhibited polymerization at 1 mM and above, and MMA3 and DMA3 at 10 ?M and above. Taken together, these results give a complex picture of how arsenicals may affect cells. Some are cytotoxic, which may prevent the cells from cycling, thereby reducing the MI. Simultaneously, at lower concentrations, these same arsenicals may react with the spindle and cause an apparent increase in MI by arresting the cells at metaphase or anaphase. Thus, the metabolites of arsenic are active not only as chromosome breaking and DNA damaging agents but can also interfere with cell division. They can effect this through interaction with the spindle potentially leading to aneuploidy, a common driving force in genomic instability and ultimately in tumor formation.",
Arsenic,1350794,"Chronic lymphocytic leukaemias and non-Hodgkin's lymphomas by histological type in farming-animal breeding workers: A population case-control study based on a priori exposure matrices Abstract: This report concerns a population based case/control study which was performed in a highly agricultural region of Italy in an effort to understand any association between chronic lymphocytic leukemia (CLL) and nonHodgkin's lymphomas (NHLs), and the exposure of workers to pesticides. The study population included workers involved in farming and animal breeding. There were 187 cases of CLLs and NHLs. The findings indicated no crop or animal showed an association with CLLs and NHLs when adjusted by exposure during childhood to farming and animal breeding. There was a nonsignificant association delineated with stannates, arsenates, phosphates, and DDT (50293) based on recall of exposures, and for stannates, arsenates, and DDT after the application of the matrices. When considering CLLs with low grade NHLs the association became significant for insecticides in general, and carbamates, and phosphates in particular according to personal recall. A risk of borderline significance for stannates and dithiocarbamates was noted as well. A significant dose response effect was noted for phosphates. The authors conclude that the association of CLLs and NHLs with work in farming and animal breeding is particularly explained as an association to pesticide exposure, particularly insecticides, and stannates, possibly related to their use in animal breeding. The independent effect of the variable exposure during childhood suggests that early exposure, including possible contact with animals, may be an important factor in the pathogenic process of these neoplasms.",
Arsenic,2088336,"Identification and modeling of a novel cloramphenicol resistance protein detected by functional metagenomics in a wetland of Lerma, Mexico Abstract: The exploration of novel antibiotic resistance determinants in a particular environment may be limited because of the presence of uncultured microorganisms. In this work, a culture-independent approach based on functional metagenomics was applied to search for chloramphenicol resistance genes in agro-industrial wastewater in Lerma de Villada, Mexico. To this end, a metagenomic library was generated in Escherichia coli DH10B containing DNA isolated from environmental samples of the residual arsenic-enriched (10 mg/ml) effl uent. One resistant clone was detected in this library and further analyzed. An open reading frame similar to a multidrug resistance protein from Aeromonas salmonicida and responsible for chloramphenicol resistance was identifi ed, sequenced, and found to encode a member of the major facilitator superfamily (MFS). Our results also showed that the expression of this gene restored streptomycin sensitivity in E. coli DH10B cells. To gain further insight into the phenotype of this MFS family member, we developed a model of the membrane protein multiporter that, in addition, may serve as a template for developing new antibiotics.",
Arsenic,710982,"Lung function decrement with arsenic exposure to drinking groundwater along River Indus: A comparative cross-sectional study Abstract: This study was designed to determine the association between chronic arsenic exposure through drinking groundwater and decrement in lung function, particularly among individuals who do not have signs of arsenic lesions, among an adult population. This was a comparative cross-sectional study conducted during the months of January to March 2009. One hundred participants ?15 years of age in each group, i.e. exposed (?100 ?g/l) and unexposed (?10 ?g/l) to arsenic, determined by testing drinking water samples (using portable kits), were compared for effects on lung function using spirometry. A structured and validated questionnaire was administered. Examination for arsenic skin lesions was also done. There was a decline in the mean adjusted FEV1 of 154.3 ml (95% CI: -324.7, 16.0; p = 0.076), in mean adjusted FVC of 221.9 ml (95% CI: -419.5, -24.3; p = 0.028), and in FEV1/FVC ratio of 2.0 (95% CI: -25.3, 29.4; p = 0.884) among participants who were exposed to arsenic compared to those unexposed. A separate model comprising a total of 160 participants, 60 exposed to arsenic concentrations ?250 ?g/l and 100 unexposed at arsenic concentrations of ?10 ?g/l, showed a decrement in mean adjusted FEV1 of 226.4 ml (95% CI: -430.4, -22.4; p = 0.030), in mean adjusted FVC of 354.8 ml (95% CI: -583.6, -126.0; p = 0.003), and in FEV1/FVC ratio of 9.9 (95% CI: -21.8, 41.6; p = 0.539) among participants who were exposed to arsenic in drinking groundwater. This study demonstrated that decrement in lung function is associated with chronic exposure to arsenic in drinking groundwater, occurring independently, and even before any manifestation, of arsenic skin lesions or respiratory symptoms. The study also demonstrated a dose-response effect of arsenic exposure and lung function decrement.",
Arsenic,1015695,"Ameliorative effect Trichosanthes dioica root against experimentally induced arsenic toxicity in male albino rats Abstract: The present study evaluated the ameliorative potential of hydroalcoholic extract of Trichosanthes dioica root (TDA) against arsenic induced toxicity in male albino rats. TDA (5 and 10mg/kg) was administered orally to rats for 20 consecutive days before oral administration of sodium arsenite (10mg/kg) for 8 days. Then the body weights, organ weights, haematological profiles, serum biochemical profile; hepatic and renal antioxidative parameters viz. lipid peroxidation, reduced and oxidized glutathione, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase and DNA fragmentation were evaluated. Pretreatment with TDA markedly and significantly normalized body weights, organ weights, haematological profiles, serum biochemical profile and significantly modulated all the hepatic and renal biochemical parameters and reduced DNA fragmentation in arsenic intoxicated rats. The present findings conclude that T. dioica root possessed remarkable ameliorative effect against arsenic induced organ toxicity in male albino rats mediated by alleviation of arsenic induced oxidative stress by multiple mechanisms.",
Arsenic,1508682,"Geochemical Implications of Brine Leakage into Freshwater Aquifers Abstract: CO(2) injection into deep saline formations as a way to mitigate climate change raises concerns that leakage of saline waters from the injection formations will impact water quality of overlying aquifers, especially underground sources of drinking water (USDWs). This paper aims to characterize the geochemical composition of deep brines, with a focus on constituents that pose a human health risk and are regulated by the U.S. Environmental Protection Agency (USEPA). A statistical analysis of the NATCARB brine database, combined with simple mixing model calculations, show total dissolved solids and concentrations of chloride, boron, arsenic, sulfate, nitrate, iron and manganese may exceed plant tolerance or regulatory levels. Twelve agricultural crops evaluated for decreased productivity in the event of brine leakage would experience some yield reduction due to increased TDS at brine-USDW ratios of &lt; 0.1, and a 50% yield reduction at &lt; 0.2 brine-USDW ratio. A brine-USDW ratio as low as 0.004 may result in yield reduction in the most sensitive crops. The USEPA TDS secondary standard is exceeded at a brine fraction of approximately 0.002. To our knowledge, this is the first study to consider agricultural impacts of brine leakage, even though agricultural withdrawals of groundwater in the United States are almost three times higher than public and domestic withdrawals.",
Arsenic,1018552,"Testicular toxicity of gallium arsenide, indium arsenide, and arsenic oxide in rats by repetitive intratracheal instillation Abstract: The testicular toxicities of two compound semiconductor materials, gallium arsenide (GaAs) and indium arsenide (InAs), and arsenic oxide (As2O3) were examined in rats by repetitive intratracheal instillation of these substances in suspension twice a week, a total of 16 times. A single instillation dose was 7.7 mg/kg in the GaAs and the InAs groups and 1.3 mg/kg in the As2O3 group. A significant decrease in sperm count and significant increase in the proportion of morphologically abnormal sperm were found in the epididymis in the GaAs group. Especially, abnormal sperm with a straight head increased markedly in this group. In the GaAs-treated rats, there was 40-fold increase in the degenerating late elongated spermatids at the postspermiation stages, stages IX, XI, and XI. From these results, it is indicated that GaAs disturbed the spermatid head transformation at the late spermiogenic phases and caused spermiation failure. InAs caused a sperm count decrease in the epididymis, though its testicular toxicity was relatively weak compared with that of GaAs. As2O3, a probable dissolution arsenic product of GaAs and InAs in vivo, did not show any testicular toxicities in this study. It seems likely that, along with arsenics, gallium and indium play a role in the testicular toxicities of GaAs and InAs.",
Arsenic,1250969,"Thioarsenate formation upon dissolution of orpiment and arsenopyrite Abstract: Thioarsenates were previously determined as dominant species in geothermal and mineral waters with excess sulfide. Here, we used batch leaching experiments to determine their formation upon weathering or industrial leaching of the arsenic-sulfide minerals orpiment (As(2)S(3)) and arsenopyrite (FeAsS) under different pH and oxygen conditions. Under acidic conditions, as expected based on their known kinetic instability at low pH, no thioarsenates formed in either of the two mineral systems. Under neutral to alkaline conditions, orpiment dissolution yielded mono-, di- and trithioarsenate which accounted for up to 43-55% of total arsenic. Thioarsenate formation upon arsenopyrite dissolution was low at neutral (4%) but significant at alkaline pH, especially under suboxic to sulfidic conditions (20-43%, mainly as monothioarsenate). In contrast to orpiment, we postulate that recombination of arsenite and sulfide in solution is of minor importance for monothioarsenate formation during alkaline arsenopyrite dissolution. We propose instead that hydroxyl physisorption lead to formation of As-OH-S surface complexes by transposition of hydroxyl anions to arsenic or iron sites. Concurrently formed ironhydroxides could provide re-sorption sites for the freshly released monothioarsenate. However, sorption experiments with goethite showed slower sorption kinetics of monothioarsenate compared to arsenite, but comparable with arsenate. The discovery that thioarsenates are released by natural weathering and industrial leaching processes and that, once they are released, have a higher mobility than the commonly-investigated species arsenite and arsenate requires future studies to consider them when assessing arsenic release in sulfidic natural or mining-impacted environments.",
Arsenic,2064136,"The Distribution of Antimony and Arsenic in Waters of the DA(0)brava Abandoned Mine Site, Slovak Republic Abstract: ",
Arsenic,1257627,"Ethanol enhances tumor angiogenesis in vitro induced by low-dose arsenic in colon cancer cells through hypoxia-inducible factor 1 alpha pathway Abstract: Health effects due to environmental exposure to arsenic are a major global health concern. Arsenic has been known to induce carcinogenesis and enhance tumor development via complex and unclear mechanism. Ethanol is also a well-established risk factor for many malignancies. However, little is known about the effects of co-exposure to arsenic and ethanol in tumor development. In this study, we investigate the signaling and angiogenic effect of co-exposure of arsenic and ethanol on different colon cancer cell lines. Results show that ethanol markedly enhanced arsenic-induced tumor angiogenesis in vitro. These responses are related to intracellular reactive oxygen species (ROS) generation, NAPDH oxidase activation, and up-regulation of PI3K/AKT and hypoxia-inducible factor 1 alpha (HIF-1?) signaling. We have also found that ethanol increase the arsenic-induced expression and secretion of angiogenic signaling molecules such as vascular endothelial growth factor (VEGF), which further confirmed the above observation. Antioxidant enzymes inhibited arsenic/ethanol-induced tumor angiogenesis, demonstrating that the responsive signaling pathways of co-exposure to arsenic and ethanol are related to ROS generation. We conclude that ethanol is able to enhance arsenic-induced tumor angiogenesis in colorectal cancer cells via the HIF-1? pathway. These results indicate that alcohol consumption should be taken into consideration in the investigation of arsenic-induced carcinogenesis in arsenic-exposed populations.",
Arsenic,1015673,"ArxA, a new clade of arsenite oxidase within the DMSO reductase family of molybdenum oxidoreductases Abstract: Arsenotrophy, growth coupled to autotrophic arsenite oxidation or arsenate respiratory reduction, occurs only in the prokaryotic domain of life. The enzymes responsible for arsenotrophy belong to distinct clades within the DMSO reductase family of molybdenum-containing oxidoreductases: specifically arsenate respiratory reductase, ArrA, and arsenite oxidase, AioA (formerly referred to as AroA and AoxB). A new arsenite oxidase clade, ArxA, represented by the haloalkaliphilic bacterium Alkalilimnicola ehrlichii strain MLHE-1 was also identified in the photosynthetic purple sulfur bacterium Ectothiorhodospira sp. strain PHS-1. A draft genome sequence of PHS-1 was completed and an arx operon similar to MLHE-1 was identified. Gene expression studies showed that arxA was strongly induced with arsenite. Microbial ecology investigation led to the identification of additional arxA-like sequences in Mono Lake and Hot Creek sediments, both arsenic-rich environments in California. Phylogenetic analyses placed these sequences as distinct members of the ArxA clade of arsenite oxidases. ArxA-like sequences were also identified in metagenome sequences of several alkaline microbial mat environments of Yellowstone National Park hot springs. These results suggest that ArxA-type arsenite oxidases appear to be widely distributed in the environment presenting an opportunity for further investigations of the contribution of Arx-dependent arsenotrophy to the arsenic biogeochemical cycle.",
Arsenic,1023872,"Differentiating copper and arsenic toxicity using biochemical biomarkers in Asellus aquaticus and Dreissena polymorpha Abstract: Biomarkers of metal exposure are well known, but how a suite of such biomarkers will respond if the metal is also an oxidizing agent or causes oxidative stress is unclear. This study compares the effects of copper and arsenic, two metals with different oxidizing potential, on freshwater invertebrates. Dreissena polymorpha and Asellus aquaticus were exposed to nominal concentrations of copper (100 microg/L) or arsenic (80 microg/L) over 7 days, and physiological stress was examined by measuring metallothionein (MT) induction, thiobarbituric acid reactive substances (TBARS), and Na(+)/K(+)-ATPase activity. Both species showed increased levels of MT during 7-day Cu exposure tests and transient changes in lipid peroxidation (TBARS) which decreased to control levels by day 7. Arsenic had no effect on TBARS and only a transitory effect on MT in D. polymorpha over 7 days, although it initially induced lipid peroxidation in A. aquaticus on day 3. No inhibition of the Na(+)/K(+)-ATPase enzyme was observed for exposed organisms, and baseline values reported here, for A. aquaticus, 1.1 micromol Pi/mg/h, and for D. polymorpha, 0.38 micromol Pi/mg/h, are probably the first reported for these species.",
Arsenic,2149331,Antioxidant and modulatory role of Chlorophytum borivilianum against arsenic induced testicular impairment Abstract: ,
Arsenic,1508580,"Protective effect of taurine on down-regulated expression of thyroid hormone receptor genes in brains of mice exposed to arsenic Abstract: This study aimed at evaluating protective effect of taurine on the down-regulated expressions of thyroid hormone receptor (TR) genes in brains of mice exposed to arsenic (As). The SPF mice were randomly divided into As exposure group, protective group, and control group. The As exposure group was administered with 4 ppm As(2)O(3) through drinking water for 60 days. The protective group was treated with both 4 ppm As(2)O(3) and 150 mg/kg taurine. The control group was given with drinking water alone. The gene expressions of TR in the mouse brains of the three groups were analyzed by real-time PCR. Their protein expressions were examined by Western blot and immunohistochemistry. Our results showed that the gene expression of TR?, a very important regulator of Camk4 transcription, was down-regulated in cerebral and cerebellar tissues of mice exposed to As. The expression of TR?1 protein in the cerebral or cerebellar tissue significantly decreased in the group exposed to As compared to the control group. However, the expressions of TR? gene and TR?1 protein were significantly rescued in the group coadministered with taurine as antioxidant. These results indicated that taurine may have the protective effect on the down-regulated expressions of TR in brains of mice exposed to As.",1
Arsenic,2064291,"The role of commitment strength in enhancing safe water consumption: Mediation analysis of a cluster-randomized trial Abstract: <strong>OBJECTIVES: </strong>The objectives of this study were to investigate the importance of commitment strength in the theory of planned behaviour (TPB) and to test whether behaviour change techniques (BCTs) aimed at increasing commitment strength indeed promote switching to arsenic-safe wells by changing commitment strength.<br /><br /><strong>DESIGN: </strong>A cluster-randomized controlled trial with four arms was conducted to compare an information-only intervention to information plus one, two, or three commitment-enhancing BCTs.<br /><br /><strong>METHODS: </strong>Randomly selected households (N = 340) of Monoharganj, Bangladesh, in seven geographically separate areas, whose members were drinking arsenic-contaminated water at baseline and had access to arsenic-safe wells, participated in this trial. The areas were randomly allocated to the four intervention arms. Water consumption behaviour, variables of the TPB, commitment strength, and socio-demographic characteristics were assessed at baseline and at 3-month follow-up by structured face-to-face interviews. Mediation analysis was used to investigate the mechanisms of behaviour change.<br /><br /><strong>RESULTS: </strong>Changes in commitment strength significantly increased the explanatory power of the TPB to predict well-switching. Commitment-enhancing BCTs - public self-commitment, implementation intentions, and reminders - increased the behaviour change effects of information by up to 50%. Mediation analyses confirmed that the BCTs indeed increased well-switching by increasing commitment strength. Unexpectedly, however, mediation via changes in behavioural intentions was the strongest mechanism of the intervention effects.<br /><br /><strong>CONCLUSIONS: </strong>Commitment is an important construct to consider in water- and health-related behaviour change and may be for other health behaviours as well. BCTs that alter behavioural intentions and commitment strength proved highly effective at enhancing the behaviour change effects of information alone. Statement of contribution What is already known on this subject? Millions of people drink contaminated water even if they have access to safe water alternatives and despite increased awareness of the consequences to health. The theory of planned behaviour (TPB) and commitment strength are predictive of safe water consumption. The potentially commitment-enhancing behaviour change techniques (BCTs) - reminders, implementation intentions, and public self-commitment - can promote health behaviours, including safe water consumption. What does this study add? Changes in commitment strength significantly added to the prediction of switching to arsenic-safe wells by the TPB. Information-plus-BCTs aimed at increasing commitment strength led to &gt;50% more well-switching than information alone. Behaviour change effects of the BCTs were mediated by changes in commitment strength and behavioural intentions.",
Arsenic,1033219,Malignant melanoma incidence and association with arsenic Abstract: The aetiology of malignant melanoma is not wholly explained by exposure to sunshine. The present of arsenic in the soil has been suggested as a possible causative factor. Geographical clustering of malignant melanoma cases in the South Western Region is demonstrated for males and this clustering is associated with the distribution of arsenic in the soil. No evidence of geographical clustering is however found for females. This suggests possible sexspecific differences in the aetiology of malignant melanoma and indicates the need for further study of the association with arsenic.,
Arsenic,1379379,"Preliminary Report on a Study of Gene-Environmental Factors Affecting the Incidence of Neural Tube Defects in Shanxi, China Abstract: In utero exposure to toxic chemicals may result in a variety of adverse health outcomes. The severity of these outcomes is dependent on the dose-duration of exposure, the timing of the exposure, as well as the genetic characteristics of the exposed individual, nutrition, and other factors. Regardless of the clinical manifestation of the exposure, each individual within a population should exhibit some biomarker that reflects the dose and duration of exposure. A diagnostic matrix that could be used to track contaminants from the environment to receptors, and to estimate the dose of exposure necessary to cause a disease, would represent a valuable tool for reducing environmentally induced disease. Improved knowledge of the major sources of exposure would enhance opportunities to reduce exposure, while improvements in the development of biomarkers of effect and sensitivity would allow health care professionals to identify those populations at greatest risk. Knowledge of sources of exposure, genetic sensitivities and early indicators of disease is needed to develop more effective prevention programs. This abstract describes an ongoing study to investigate the utility of a matrix of biomarkers of exposure and effect in a population with a high frequency of congenital malformations. The study is being conducted in Shanxi Province, China, which is located at 300 km west of Beijing. The area has 1 of the highest rates of birth defects in the world. In 2003, the frequency of neural tube defects (NTDs) in high risk areas of Shanxi was reported to be ~139/10,000 live births. Although a portion of these birth defects is likely to be related to nutrition, it is also likely that environmental factors play a significant role. Major sources of exposure in Taiyuan and surrounding areas include polycyclic aromatic hydrocarbons (PAHs) and arsenic as a result of the combustion of coal and other products for heating and cooking. The current study is measuring concentrations of PAHs in selected households (indoor air and dust). These will be tracked to human tissues through measurements of biomarkers in blood, urine, hair and placenta from recruited children and parents of children born with NTDs, as well as children and parents of children from a matched control population. The significance of the relationship between each of these biomarkers and the incidence of NTDs will be determined. In addition, single nucleotide polymorphisms (SNPs) in xenobiotic metabolizing enzymes will be measured in case and control subjects to investigate genetic sensitivities that may predispose an individual to a congenital malformation. Preliminary data from coal dust and placenta samples indicate that arsenic concentrations are relatively low. Samples of house dust collected in October 2004 revealed carcinogenic PAH concentrations in dust ranging from 5,000 to 56,000 ng/m2. The analysis of DNA adducts in placenta demonstrates a significant increase in the less polar bulky adducts in children born with an NTD (3.37 adducts [A] +/- 1.27 x 10(9) relative adduct level [RAL]) when compared to matched controls (1.07 A +/- 0.81 x 10(9) RAL). More work is needed to understand the genetic sensitivities that may affect the retention rate of our chemicals of concern and the risk of NTDs. Future efforts will be geared towards measuring biomarkers of early biological effect (p53 and p21 levels) and altered structure / function (chromosome aberrations, SCEs).",
Arsenic,1348504,"Involvement of p38 mitogen-activated protein kinase in the cell growth inhibition by sodium arsenite Abstract: It is well-known that p38 mitogen-activated protein kinase (p38MAPK) participates in cellular responses to mitogenic stimuli, environmental and genotoxic stresses, and apoptotic agents. Although there are several reports on p38MAPK in relation to cell growth and apoptosis, the exact mechanism of p38MAPK-mediated cell growth regulation remains obscure. Here, we examined possible roles of p38MAPK in the sodium arsenite-induced cell growth inhibition in NIH3T3 cells. Sodium arsenite induced transient cell growth delay with marked activation of p38MAPK. In addition, arsenite induced CDK inhibitor p21(CIP1/WAF1) and enhanced its binding to the CDK2, which resulted in inhibition of CDK2 activity. The levels of cyclin D1 expression and the CDK4 kinase activity were also significantly reduced. pRB was hypophosphorylated by sodium arsenite. SB203580, a specific inhibitor of p38MAPK, blocked arsenite-induced growth inhibition as well as the arsenite-induced p21(CIP1/WAF1) expression. Expression of dominant negative p38MAPK also blocked arsenite-induced p21(CIP1/WAF1) expression. Inhibited-CDK2 activity was also completely reversed by SB203580 or expression of dominant negative p38MAPK, while the decreased-cyclin D1 protein by the compound was not restored. These data demonstrate a possible link between the activation of p38MAPK and induction of p21(CIP1/WAF1), suggesting that the activation of p38MAPK is, at least in part, related to the cell growth inhibition by sodium arsenite.",
Arsenic,2149174,"The die is cast - Arsenic exposure in early life and disease susceptibility Abstract: Early life exposure to arsenic in humans and mice produces similar patterns of disease in later life. Given the long interval between exposure and effect, epigenetic effects of early life exposure to arsenic may account for development and progression of disease in both species. Mode of action and dosimetric studies in the mouse may help assess the role of age at exposure as a factor in susceptibility to the toxic and carcinogenic effects of arsenic in humans.",
Arsenic,1597351,"Synthesis of novel polyazacryptands for recognition of tetrahedral oxoanions and their X-ray structures Abstract: The Mannich reaction of tris(pyrrolyl-?-methyl)amine (H3tpa) with a mixture of formaldehyde and primary amine hydrochloride (methyl or ethyl) gave two novel macrobicyclic molecules: a hexapyrrolic pentaazacryptand and an unusual pentapyrrolic tetraazacryptand, which were separated by column chromatography and their structures were determined by X-ray diffraction method. The analogous reaction using benzylamine hydrochloride yielded the encapsulated chloride anion complex in 16% yield even after neutralization with aqueous K2CO3, which was also characterized by X-ray diffraction. In addition, the anion binding properties of these macrobicycles were investigated by NMR titration methods, and the binding constants for halides and oxoanions were determined with the EQNMR program. The cavity of the hexapyrrolic pentaazacryptand is flexible and large enough enabling it to form inclusion complexes with the smaller size fluoride ion as well as with the bulkier oxoanions. This was demonstrated by (19)F NMR spectroscopy and by the X-ray structures of the encapsulated sulfate, phosphate, and arsenate ion complexes. Upon complexation the distance between the bridgehead nitrogen atoms changes. Further, anion induced conformational changes were observed in the structures of the oxoanion complexes, particularly in the arsenate structure which represents the first azacryptand encapsulated structure of an arsenate ion. Furthermore, the competition crystallization experiment showed that the phosphate ion complex of the hexapyrrolic pentaazacryptand is the sole crystallization product from an aqueous-organic medium, as confirmed by IR and powder X-ray diffraction studies.",
Arsenic,2149266,"Groundwater development in the CCOP countries: Challenges and opportunities Abstract: CCOP stands for Coordinating Committee for Geoscience Programmes in East and Southeast Asia—an intergovernmental organization comprising of eleven Member Countries: Cambodia, China, Indonesia, Japan, Malaysia, Papua New Guinea, the Philippines, Republic of Korea, Singapore, Thailand and Vietnam. CCOP’s mission is to facilitate and coordinate the implementation of applied geoscience programmes in the region to contribute to economic development and an improved quality of life within the region. As an intergovernmental geoscience organization, CCOP organizes its activities in seven programmes, including the groundwater programme, which promotes capacity building, technology transfer, exchange of information and institutional linkages for sustainable groundwater resource development in CCOP Member Countries. The overview of the status of groundwater development within the CCOP Member Countries will be elaborated highlighting quantity and quality challenges for its sustainable development. Some examples of challenges are the large numbers of people in these regions that still have no access to an improved water source; decline in the availability of freshwater, particularly in large river basins due to global warming; saltwater intrusion; arsenic pollution of groundwater, etc. Finally, the emphasis of the importance of capacity building in sound groundwater management will be shown as the contribution of CCOP to its members. The recommendation to capture the opportunities for groundwater development in CCOP Member Countries will be presented and discussed.",
Arsenic,2298702,"Determination of lewisite constituents in aqueous samples using hollow-fibre liquid-phase microextraction followed by gas chromatography-mass spectrometry Abstract: The applicability of hollow-fibre liquid-phase microextraction for extracting 2-chlorovinyldichloroarsine (lewisite 1), bis(2-chlorovinyl)chloroarsine (lewisite 2), tris(2-chlorovinyl)arsine (lewisite 3) and arsenic trichloride from aqueous samples is reported. Parameters affecting the extraction efficiency of these chemicals were optimised. These parameters included the type of derivatising agent, extraction solvent, derivatisation method, pH, ionic strength, stirring speed and extraction time. A linear range between 0.002 and 0.2 ?g/mL was established for the lewisites with good square regression coefficients (0.9955-0.9992). Good reproducibility with relative standard deviations (RSDs) from 8 to 10 % was achieved. The limit of detection was 0.002 ?g/mL for the lewisites and 0.005 ?g/mL for arsenic trichloride (3:1 signal-to-noise ratio). The extraction method was validated with a proficiency test sample issued by the Organisation for the Prohibition of Chemical Weapons (OPCW). The rapidity and precision of the new method should help deter against the employment of lewisite as a chemical warfare agent: its use could be confirmed easily from analysis of aqueous samples.",
Arsenic,2347695,"Effect of left ventricular diastolic dysfunction on outcomes of atrial fibrillation ablation Abstract: Left ventricular diastolic dysfunction (LVDD) is an important pathogenic factor for atrial fibrillation (AF). There are few data on the effect of LVDD on recurrence of AF after catheter ablation. A cohort of 124 patients (59.9 ± 11.7 years, 73.9% male, and 55% with paroxysmal AF) with recalcitrant AF and normal left ventricular systolic function (left ventricular ejection fraction ?50%) undergoing ablation was studied. Each patient underwent transthoracic echocardiography, and LVDD was meticulously graded using rhythm-independent (AF or sinus rhythm) transmitral and tissue Doppler parameters. Patients underwent catheter ablation of AF using a stepwise protocol. All patients were followed up at 3, 6, and 12 months with recurrent AF (&gt;30 seconds) captured by electrocardiography and/or 7-day monitor. Kaplan-Meier survival analysis and Cox proportional hazards model were used. There was no LVDD in 72 patients (58%), whereas 33 (26.6%), 10 (8.1%), and 9 (7.3%) patients had grades 1, 2, and 3 LVDD, respectively. AF recurred in 49 patients (39.5%) with median time to recurrence of 248 days. Patients with higher grade of LVDD were increasingly more likely to have recurrence (37.5% for no LVDD and 30.3%, 60%, and 66.7% for grades 1, 2, and 3 LVDD, respectively). Significant LVDD (grade 2 or 3) was an independent predictor of recurrence (hazard ratio 2.6, p = 0.009) after adjusting for persistent (vs paroxysmal) AF and left atrial volume. In conclusion, patients with more severe LVDD have a higher risk of AF recurrence after catheter ablation. These patients may derive less benefit from ablation or may require a more extensive ablation approach.",
Arsenic,1032630,On living in a arsenical atmosphere. Part I: Hair arsenic Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN POLLUTION FOODSTUFFS,
Arsenic,1034607,"Zeeman effect electrothermal atomic absorption spectrophotometry with matrix modification for the determination of arsenic in urine Abstract: Arsenic was determined in urine by electrothermal atomic absorption spectrophotometry using Zeeman Effect background correction and after matrix modification with 5% nickel nitrate. Mean recovery of urine samples spiked with 100 ?g.L?1 dimethylarsinic acid was 97.9 ?g.L?1. Within-run CV was 2.4%, between-run CV was 7.3% and the detection limit was determined to be 10.0 ?g.L?1. The method can be used for the rapid screening of urine samples for elevated arsenic levels.",
Arsenic,2345792,"Microscale investigations of the fate of heavy metals associated to iron-bearing particles in a highly polluted stream Abstract: As it flows through a dense steelmaking area, the Fensch River does transport iron-rich particles and colloids, displaying high contents in metallic contaminants (Zn, Cr, Pb, Cu, Ni, and As). Chemical analysis using inductively coupled plasma mass spectrometry (ICP-MS) was carried out on three compartments-waters, suspended materials, and sediments-along the river linear. The variations of metallic trace element concentrations along the river were shown to be partially related to external inputs (industrial and domestic wastewaters and urban surfaces leaching). However, some discrepancies of element partitioning were evidenced. Pb, Cu, and Mn tend to concentrate in suspended particulate and in dissolved fraction, while Cr and As follow the trend of Fe and concentrate within sediments of the most downstream station, just before the junction with Moselle waters. Zn appears strongly associated to iron-rich particles, resulting in a decrease of its concentration in waters for the last station. Along the Fensch linear, the variation of metal partitioning between water and particulate phases is accompanied with strong modifications of the nature and mineralogy of iron-rich particles, as evidenced by microanalyses using electron and X-ray beams. The combination of bulk analyses using ICP-MS and microanalyses applied to the three compartments allowed us to propose a three-step process &quot;settling-weathering-resuspension&quot; to explain Zn partitioning.",
Arsenic,1340129,"Herpes simplex virus 2 infection impacts stress granule accumulation Abstract: Interference with stress granule (SG) accumulation is gaining increased appreciation as a common strategy used by diverse viruses to facilitate their replication and to cope with translational arrest. Here, we examined the impact of infection by herpes simplex virus 2 (HSV-2) on SG accumulation by monitoring the localization of the SG components T cell internal antigen 1 (TIA-1), Ras-GTPase-activating SH3-domain-binding protein (G3BP), and poly(A)-binding protein (PABP). Our results indicate that SGs do not accumulate in HSV-2-infected cells and that HSV-2 can interfere with arsenite-induced SG accumulation early after infection. Surprisingly, SG accumulation was inhibited despite increased phosphorylation of eukaryotic translation initiation factor 2? (eIF2?), implying that HSV-2 encodes previously unrecognized activities designed to maintain translation initiation downstream of eIF2?. SG accumulation was not inhibited in HSV-2-infected cells treated with pateamine A, an inducer that works independently of eIF2? phosphorylation. The SGs that accumulated following pateamine A treatment of infected cells contained G3BP and PABP but were largely devoid of TIA-1. We also identified novel nuclear structures containing TIA-1 that form late in infection. These structures contain the RNA binding protein 68-kDa Src-associated in mitosis (Sam68) and were noticeably absent in infected cells treated with inhibitors of viral DNA replication, suggesting that they arise as a result of late events in the virus replicative cycle.",
Arsenic,8430,"Skin cancer and water arsenic in Lane County, Oregon Abstract: It was expected that the incidence of skin cancer would be related to the known high arsenic levels in water supplies of Lane County, Oregon. Incidence rates were based on all histopathologically confirmed cases among Lane County residents diagnosed during 1958-1971 and were compared to mean water arsenic levels measured during 1968-1974. Basal cell carcinoma had a mean annual incidence rate of 88 per 100,000, a 5:4::M:F sex ratio, and an increasing risk for both sexes in urban areas. Squamous cell carcinoma incidence was 50 per 100,000 and showed 2:1:M:F sex ratio but no urban predilection. Neither type of skin cancer was directly related to the arsenic levels as expected, although sporadic individuals with sufficient exposure could manifest the relationship. Fewer than expected drinking water sources were found to contain high arsenic content, so that the Lane County data do not necessarily contradict previous reports of positive correlation. The basal cell carcinoma pattern suggested that this disease might be potentiated by urban air pollutants.",
Arsenic,628028,"Toenails as a biomarker of inorganic arsenic intake from drinking water and foods Abstract: Toenails were used recently in epidemiological and environmental health studies as a means of assessing exposure to arsenic from drinking water. While positive correlations between toenail and drinking-water arsenic concentrations were reported in the literature, a significant percentage of the variation in toenail arsenic concentration remains unexplained by drinking-water concentration alone. Here, the influence of water consumption at home and work, food intake, and drinking-water concentration on toenail arsenic concentration was investigated using data from a case-control study being conducted in 11 counties of Michigan. The results from 440 controls are presented. Log-transformed drinking-water arsenic concentration at home was a significant predictor (p < .05) of toenail arsenic concentration (R2 = .32). When arsenic intake from consumption of tap water and beverages made from tap water (microg/L arsenic x L/d = microg/d) was used as a predictor variable, the correlation was markedly increased for individuals with >1 microg/L arsenic (R2 = .48). Increased intake of seafood and intake of arsenic from water at work were independently and significantly associated with increased toenail arsenic concentration. However, when added to intake at home, work drinking-water exposure and food intake had little influence on the overall correlation. These results suggest that arsenic exposure from drinking-water consumption is an important determinant of toenail arsenic concentration, and therefore should be considered when validating and applying toenails as a biomarker of arsenic exposure.",
Arsenic,486712,"Evaluation of essential and toxic metals by ultrasound-assisted acid leaching from scalp hair samples of children with macular degeneration patients Abstract: Background: The causes of night blindness in children are multifactorial and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition. Method: An ultrasonic-assisted acid leaching procedure was developed as a sample pretreatment for the determination of Zn, Cu, Cd, As and Pb in human scalp hair samples of night blindness male children with age between 5 to 15 y and compared with the children without vision anomalies that lived in the same localities. The effects of different factors on acid leaching of metals, such as preintensification time (without ultrasonic stirring) after treatment of acid mixture, exposure time to ultrasound and temperature of the ultrasonic bath have been investigated. The proposed method was validated by certified reference samples of scalp hair CRM 397. The wet acid digestion method was used to obtain the total metal concentration in both scalp hair and CRM samples. Cu and Zn in leachates and digests were measured by flame atomic absorption spectrometry (FAAS) using a conventional air/acetylene flame, while Cd and Pb were determined by electrothermal atomic absorption spectrometry (ETAAS) under optimized conditions. Results: It was observed that at optimal conditions, the recovery for Zn, Cd, Pb, As and Cu were 98%, 98.5%, 96%, 97.2% and 94% respectively. The mean values of Zn and Cu in scalp hair samples of children having night blindness were significantly lower as compared to normal healthy children (p for Zn < 0.001 and Cu < 0.003), while the level of toxic metals As, Cd and Pb were significantly higher in children having ocular problems as related to normal children (p As < 0.0074, Cd < 0.001 and lead < 0.004). Conclusion: These data present guidance to clinicians and other professional investigating deficiency of essential trace metals and excessive level of toxic metals in biological samples. (c) 2006 Elsevier B.V. All rights reserved.",
Arsenic,1340736,"Hydroxyethyl disulfide as an efficient metabolic assay for cell viability in vitro Abstract: Cell viability assays have a variety of well known practical and technical limitations. All the available approaches have disadvantages, such as non-linearity, high background and cumbersome protocols. Several commonly used tetrazolium chemicals rely upon generation of a colored formazan product formed by mitochondrial reduction of these compounds via phenazine methosulfate (PMS). However, sensitivity is inherently limited because their reduction relies on mitochondrial bioreduction and cellular transport of PMS, as well as accessibility to tetrazolium chemicals. In this study, we identify hydroxethyldisulfide (HEDS) as an inexpensive probe that can measure cellular metabolic activity without the need of PMS. In tissue culture medium, HEDS accurately quantitated metabolically active live cells in a linear manner superior to tetrazolium based and other assays. Cell toxicity produced by chemotherapeutics (cisplatin, etoposide), oxidants (hydrogen peroxide, acetaminophen), toxins (phenyl arsine oxide, arsenite) or ionizing radiation was rapidly determined by the HEDS assay. We found that HEDS was superior to other commonly used assays for cell viability determinations in its solubility, membrane permeability, and intracellular conversion to a metabolic reporter that is readily transported into the extracellular medium. Our findings establish the use of HEDS in a simple, rapid and low cost assay to accurately quantify viable cells.",
Arsenic,116615,"Examination of the effects of arsenic on glucose homeostasis in cell culture and animal studies: Development of a mouse model for arsenic-induced diabetes Abstract: Previous epidemiologic studies found increased prevalences of type 2 diabetes mellitus in populations exposed to high levels of inorganic arsenic (iAs) in drinking water. Although results of epidemiologic studies in low-exposure areas or occupational settings have been inconclusive, laboratory research has shown that exposures to iAs can produce effects that are consistent with type 2 diabetes. The current paper reviews the results of laboratory studies that examined the effects of iAs on glucose metabolism and describes new experiments in which the diabetogenic effects of iAs exposure were reproduced in a mouse model. Here, weanling male C57BL/6 mice drank deionized water with or without the addition of arsenite (25 or 50 ppm As) for 8 weeks. Intraperitoneal glucose tolerance tests revealed impaired glucose tolerance in mice exposed to 50 ppm As, but not to 25 ppm As. Exposure to 25 and 50 ppm As in drinking-water resulted in proportional increases in the concentration of iAs and its metabolites in the liver and in organs targeted by type 2 diabetes, including pancreas, skeletal muscle and adipose tissue. Dimethylarsenic was the predominant form of As in the tissues of mice in both 25 and 50 ppm groups. Notably, the average concentration of total speciated arsenic in livers from mice in the 50 ppm group was comparable to the highest concentration of total arsenic reported in the livers of Bangladeshi residents who had consumed water with an order of magnitude lower level of iAs. These data suggest that mice are less susceptible than humans to the diabetogenic effects of chronic exposure to iAs due to a more efficient clearance of iAs or its metabolites from target tissues.",
Arsenic,1015770,"Impact of irrigation with high arsenic burdened groundwater on the soil-plant system: Results from a case study in the Inner Mongolia, China Abstract: Consequences of irrigation by arsenic (As) enriched groundwater were assigned in the Hetao Plain, part of Chinas' Inner Mongolia Autonomous Region. Examinations followed the As flow path from groundwater to soil and finally plants. A sunflower and a maize field were systematically sampled, each irrigated since three years with saline well water, characterized by elevated As concentrations (154 and 238?gL(-1)). The annual As input per m(2) was estimated as 120 and 186mg, respectively. Compared to the geogenic background, As concentrations increased toward the surface with observed enrichments in topsoil being relatively moderate (up to 21.1mgkg(-1)). Arsenic concentrations in plant parts decreased from roots toward leaves, stems and seeds. It is shown that the bioavailability of As is influenced by a complex interplay of partly counteracting processes. To prevent As enrichment and soil salinization, local farmers were recommended to switch to a less problematic water source.",
Arsenic,1519075,"Differences in urinary arsenic metabolites between diabetic and non-diabetic subjects in Bangladesh Abstract: Ingestion of inorganic arsenic (iAs) is considered to be related to the development of diabetes mellitus. In order to clarify the possible differences in the metabolism in diabetics, we measured urinary iAs metabolites in diabetic cases and non-diabetic control subjects in Faridpur, an arsenic-contaminated area in Bangladesh. Physician-diagnosed type 2 diabetic cases (140 persons) and non-diabetic controls (180 persons) were recruited. Drinking water and spot urine samples were collected. Mean concentrations of total arsenic in drinking water did not differ between cases (85.1 ?g/L) and controls (85.8 ?g/L). The percentage of urinary iAs (iAs%) was significantly lower in cases (8.6%) than in controls (10.4%), while that of dimethylarsinic acid (DMA%) was higher in cases (82.6%) than in controls (79.9%). This may have been due to the higher secondary methylation index (SMI) in the former (11.6) rather than the latter (10.0). Adjusting for matching factors (sex and unions), and the additional other covariates (age and water arsenic) significantly attenuated the differences in iAs%, SMI, and DMA%, respectively, though the difference in monomethylarsonic acid% was newly significant in the latter adjustment. Our study did not suggest any significant differences in urinary arsenic metabolites between diabetic and non-diabetic subjects.",
Arsenic,627166,"Activation of inflammation/NF-kappaB signaling in infants born to arsenic-exposed mothers Abstract: The long-term health outcome of prenatal exposure to arsenic has been associated with increased mortality in human populations. In this study, the extent to which maternal arsenic exposure impacts gene expression in the newborn was addressed. We monitored gene expression profiles in a population of newborns whose mothers experienced varying levels of arsenic exposure during pregnancy. Through the application of machine learning-based two-class prediction algorithms, we identified expression signatures from babies born to arsenic-unexposed and -exposed mothers that were highly predictive of prenatal arsenic exposure in a subsequent test population. Furthermore, 11 transcripts were identified that captured the maximal predictive capacity to classify prenatal arsenic exposure. Network analysis of the arsenic-modulated transcripts identified the activation of extensive molecular networks that are indicative of stress, inflammation, metal exposure, and apoptosis in the newborn. Exposure to arsenic is an important health hazard both in the United States and around the world, and is associated with increased risk for several types of cancer and other chronic diseases. These studies clearly demonstrate the robust impact of a mother's arsenic consumption on fetal gene expression as evidenced by transcript levels in newborn cord blood.",
Arsenic,1029215,"Identification of low inorganic and total grain arsenic rice cultivars from Bangladesh Abstract: For the world's population, rice consumption is a major source of inorganic arsenic (As), a nonthreshold class 1 carcinogen. Reducing the amount of total and inorganic As within the rice grain would reduce the exposure risk. In this study, grain As was measured in 76 cultivars consisting of Bangladeshi landraces, improved Bangladesh Rice Research Institute (BRRI) cultivars, and parents of permanent mapping populations grown in two field sites in Bangladesh, Faridpur and Sonargaon, irrigated with As-contaminated tubewell water. Grain As ranged from 0.16 to 0.74 mg kg(-1) at Faridpur and from 0.07 to 0.28 mg kg(-1) at Sonargaon. Highly significant cultivar differences were detected and a significant correlation (r = 0.802) in the grain As between the two field sites was observed, indicating stable genetic differences in As accumulation. The cultivars with the highest concentration of grain As were the Bangladeshi landraces. Landraces with red bran had significantly more grain As than the cultivars with brown bran. The percent of inorganic As decreased linearly with increasing total As, but genetic variation within this trend was identified. A number of local cultivars with low grain As were identified. Some tropical japonica cultivars with low grain As have the potential to be used in breeding programs and genetic studies aiming to identify genes which decrease grain As.",
Arsenic,624000,"Oridonin Confers Protection against Arsenic-Induced Toxicity through Activation of the Nrf2-Mediated Defensive Response Abstract: BACKGROUND: Groundwater contaminated with arsenic imposes a big challenge to human health worldwide. Using natural compounds to subvert the detrimental effects of arsenic represents an attractive strategy. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a critical regulator of the cellular antioxidant response and xenobiotic metabolism. Recently, activation of the Nrf2 signaling pathway has been reported to confer protection against arsenic-induced toxicity in a cell culture model. OBJECTIVES: The goal of the present work was to identify a potent Nrf2 activator from plants as a chemopreventive compound and to demonstrate the efficacy of the compound in battling arsenic-induced toxicity. RESULTS: Oridonin activated the Nrf2 signaling pathway at a low subtoxic dose and was able to stabilize Nrf2 by blocking Nrf2 ubiquitination and degradation, leading to accumulation of the Nrf2 protein and activation of the Nrf2-dependent cytoprotective response. Pretreatment of UROtsa cells with 1.4 Ã‚ÂµM oridonin significantly enhanced the cellular redox capacity, reduced formation of reactive oxygen species (ROS), and improved cell survival after arsenic challenge. CONCLUSIONS: We identified oridonin as representing a novel class of Nrf2 activators and illustrated the mechanism by which the Nrf2 pathway is activated. Furthermore, we demonstrated the feasibility of using natural compounds targeting Nrf2 as a therapeutic approach to protect humans from various environmental insults that may occur daily. [ABSTRACT FROM AUTHOR] Copyright of Environmental Health Perspectives is the property of Superintendent of Documents and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1026300,"In vitro and in vivo reduction of sodium arsenite induced toxicity by aqueous garlic extract Abstract: <strong>BACKGROUND: </strong>Arsenic is ubiquitous in the environment, and chronic or acute exposure through food and water as well as occupational sources can contribute to a well-defined spectrum of disease. Despite arsenic being a health hazard and a well-documented human carcinogen, a safe, effective and specific preventive or therapeutic measure for treating arsenic induced toxicity still eludes us.<br /><br /><strong>OBJECTIVE: </strong>This study was undertaken to evaluate the therapeutic efficacy of aqueous garlic (Allium sativum L.) extract (AGE) in terms of normalization of altered biochemical parameters particularly indicative of oxidative stress following sodium arsenite (NaAsO(2)) exposure and depletion of inorganic arsenic burden, in vitro and in vivo.<br /><br /><strong>RESULTS: </strong>AGE (2mg/ml) co-administered with 10 microM NaAsO(2) attenuated arsenite induced cytotoxicity, reduced intracellular reactive oxygen species (ROS) level in human malignant melanoma cells (A375), human keratinocyte cells (HaCaT) and in cultured human normal dermal fibroblast cells. Moreover, AGE application in NaAsO(2) intoxicated Sprague-Dawley rats resulted in a marked inhibition of tissue lipid peroxide generation; enhanced level of total tissue sulfhydryl groups and glutathione; and also increased the activities of antioxidant enzymes, superoxide dismutase and catalase to near normal. An increase in blood ROS level and myeloperoxidase activity in arsenic-intoxicated rats was effectively prevented by AGE administration. AGE was also able to counter arsenic mediated incongruity in blood hematological variables and glucose level.<br /><br /><strong>CONCLUSIONS: </strong>The restorative property of AGE was attributed to its antioxidant activity, chelating efficacy, and/or oxidizing capability of trivalent arsenic to its less toxic pentavalent form. Taken together, evidences indicate that AGE can be a potential protective regimen for arsenic mediated toxicity.",
Arsenic,1032620,Determination of arsenic in coal and in insecticides by atomic absorption spectroscopy Abstract: ,
Arsenic,1070369,"Analysis of elemental concentration using ICP-AES and pathogen indicator in drinking water of Qasim Abad, District Rawalpindi, Pakistan Abstract: The present study was conducted to investigate drinking water quality (groundwater) from water samples taken from Qasim Abad, a locality of approximately 5,000 population, situated between twin cities Rawalpindi and Islamabad in Pakistan. The main sources of drinking water in this area are water bores which are dug upto the depth of 250-280 ft in almost every house. The study consists of the determination of physico-chemical properties, trace metals, heavy metals, rare earth elements and microbiological quality of drinking water. The data showed the variation of the investigated parameters in samples as follows: pH 6.75 to 8.70, electrical conductivity 540 to 855 ?S/cm, total dissolved solids 325.46 to 515.23 ppm and dissolved oxygen 1.50 to 5.64 mg/L which are within the WHO guidelines for drinking water quality. The water samples were analysed for 30 elements (aluminium, iron, magnesium, manganese, silicon, zinc, molybdenum, titanium, chromium, nickel, tungsten, silver, arsenic, boron, barium, beryllium, cadmium, cobalt, copper, gallium, mercury, lanthanum, niobium, neodymium, lead, selenium, samarium, tin, vanadium and zirconium) by using inductively coupled plasma atomic emission spectroscopy. The organic contamination was detected in terms of most probable number (MPN) of faecal coliforms. Overall, elemental levels were lower than the recommended values but three water bores (B-1, B-6, B-7) had higher values of iron (1.6, 2.206, 0.65 ppm), two water bores (B-1, B-6) had higher values of aluminium (0.95, 1.92 ppm), respectively, and molybdenum was higher by 0.01 ppm only in one water bore (B-11). The total number of coliforms present in water samples was found to be within the prescribed limit of the WHO except for 5 out of 11 bore water samples (B-2, B-3, B-4, B-8, B-11), which were found in the range 5-35 MPN/100 mL, a consequence of infiltration of contaminated water (sewage) through cross connection, leakage points and back siphoning.",
Arsenic,2278031,"Investigation on the long-term storage and fate of arsenic obtained as a treatment residual: A case study Abstract: In several places in India, activated alumina is used for effective removal of arsenic from contaminated ground water used for drinking purposes. Once exhausted, activated alumina is regenerated and reused for number of cycles. Regeneration of activated alumina generates treatment residuals containing arsenic, disposal of which needs care so as to avoid further pollution of the neighbouring environment. In the present study, a suitable stabilization and disposal method for the treatment residuals inside a well aerated coarse sand filter bed has been developed. Standard leaching tests carried out with the stabilized treatment residual indicated that the leaching of arsenic from the stabilized treatment residual was minimum, and was within the regulatory limit. Water quality data of all the wells located within 100m from the sand filter were monitored for nearly four years and no adverse impact of disposal of arsenic-laden treatment residuals in the sand filter was observed.",
Arsenic,1352980,"Binary Pnictogen Azidesu-An Experimental and Theoretical Study: [As(N-3)(4)](-), [Sb(N-3)(4)](-), and [Bi(N-3)(5)(dmso)](2-) Abstract: ",
Arsenic,627581,"Arsenic-induced mitochondrial instability leading to programmed cell death in the exposed individuals Abstract: In West Bengal, India, more than 6 million people in nine districts are exposed to arsenic through drinking water. It is regarded as the greatest arsenic calamity in the world. Arsenic is a well-documented human carcinogen, which does not induce cancer in any other animal model. Interestingly, at lower concentrations, arsenic is known to induce apoptosis in various cancer cell lines in vitro. We have studied apoptosis in human peripheral blood mononuclear cells (PBMC) of 30 arsenic exposed skin lesion individuals by annexin V-FITC staining and compared with 28 unexposed individuals. The percentage of apoptotic cells in individuals with skin lesions was significantly higher (p<0.001) in comparison to unexposed individuals. In the exposed individuals with skin lesions, there were elevated levels of intracellular reactive oxygen species (ROS), mitochondrial membrane permeability and increased cytochrome c release, leading to increased downstream caspase activity. Arsenic-induced DNA damage was confirmed by DNA ladder formation and confocal microscopy. We also observed that chronic arsenic exposure reduced Bcl-2/Bax ratio and also resulted in cell cycle arrest of PBMC in G0/G1 phase. All these observations indicate that mitochondria-mediated pathway may be responsible for arsenic-induced apoptosis.",
Arsenic,626915,"Disruption of dioxin-inducible phase I and phase II gene expression patterns by cadmium, chromium, and arsenic Abstract: Recent work suggesting that cellular oxidative stress exerts an inhibitory effect on aromatic hydrocarbon receptor (AHR)-dependent gene expression led us to test the hypothesis that pro-oxidant environmental pollutants might alter the induction of detoxification genes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an AHR ligand. We found that, in mouse hepatoma Hepa-1 cells, TCDD-inducible cytochrome P450, Cyp1a1, and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase (Nqo1) mRNA accumulation were differentially affected by cadmium (Cd2+), chromium (Cr6+), and arsenic (As3+). Cadmium or arsenic did not change Cyp1a1 mRNA levels but did enhance TCDD-inducible levels of Nqo1 mRNA, an effect that paralleled the ability of these metals to activate a -galactosidase gene reporter system regulated by an electrophile response promoter element. Chromium inhibited mRNA accumulation for both Cyp1a1 and Nqo1. Manipulation of cellular thiol status did not modify the response to combined chromium-TCDD exposure, suggesting that the response was not caused by oxidative stress. Chromium did not block DNA-binding competence of the AHR and did not have an effect on mRNA stability, but it inhibited Cyp1a1 gene transcription and the expression of an AHR-dependent luciferase reporter. These data indicate that coexposure to pro-oxidant metals and AHR ligands, which is common in the environment, can disrupt the regulation of phase I and phase II detoxification genes, leading to imbalances in gene expression that may have important consequences for the toxicity of complex mixtures. Mol. Carcinog. 28:225-235, 2000. © 2000 Wiley-Liss, Inc.",
Arsenic,1018630,"Ionizing radiation: Future etiologic research and preventive strategies Abstract: Estimates of cancer risks following exposure to ionizing radiation traditionally have been based on the experience of populations exposed to substantial (and known) doses delivered over short periods of time. Examples include survivors of the atomic bombings at Hiroshima and Nagasaki, and persons treated with radiation for benign or malignant disease. Continued follow-up of these populations is important to determine the long-term effects of exposure in childhood, to characterize temporal patterns of excess risk for different types of cancer, and to understand better the interactions between radiation and other host and environmental factors. Most population exposure to radiation occurs at very low dose rates. For low linear energy transfer (LET) radiations, it often has been assumed that cancer risks per unit dose are lower following protracted exposure than following acute exposure. Studies of nuclear workers chronically exposed over a working lifetime provide data that can be used to test this hypothesis, and preliminary indications are that the risks per unit dose for most cancers other than leukemia are similar to those for acute exposure. However, these results are subject to considerable uncertainty, and further information on this question is needed. Residential radon is the major source of population exposure to high-LET radiation. Current estimates of the risk of lung cancer due to residential exposure to radon and radon daughters are based on the experience of miners exposed to much higher concentrations. Data indicate that lung cancer risk among miners is inversely associated with exposure rate, and also is influenced by the presence of other lung carcinogens such as arsenic in the mine environment. Further study of populations of radon-exposed miners would be informative, particularly those exposed at below-average levels. More direct evidence on the effects of residential exposure to radon also is desirable but might be difficult to come by, as risks associated with radon levels found in most homes might be too low to be quantified accurately in epidemiological studies.",
Arsenic,1021590,"A medical geology study of an arsenic-contaminated area in Kouhsorkh, NE Iran Abstract: High concentrations of arsenic were determined in sediments from the Kouhsorkh area, Khorasan province, NE Iran. The main rock formations in the area consist of Tertiary volcanic rocks as Tuffaceous sandstone, polymictic conglomerate and andesite. Furthermore, some As-Sb-Au mineralization occurred in this area. Concentrations of arsenic in sediments were determined to range between 4.2 and 268.2 ppm, exceeding US EPA (2004) limits. It seems that young volcanic activity is one of the most important factors for arsenic contamination in this area. The first stage of this medical geology study was done at 2 villages in the Kouhsorkh area in which the arsenic concentration in water is high. People in this residential area suffer from skin diseases including hyperpigmentation, hypopigmentation, keratosis on head, hands, and feet. The 24-h urine specimens were tested for arsenic, the level of total arsenic in urine were determined to range between 13.66 and 75.92 ?g/l day, exceeding permissible limits from 5 to 40 ?g/day. More systematic studies are needed to determine the link between As exposure and its related diseases.",
Arsenic,1597399,Residual leachability of CCA-contaminated soil after treatment with biodegradable chelating agents and lignite-derived humic substances Abstract: ,
Arsenic,1348692,"Long-Term Changes in the Bioaccumulation of As, Cd, Pb, and Hg in Macroinvertebrates from the Elbe River (Czech Republic) Abstract: ",
Arsenic,1337338,"Low-dose risk assessment for arsenic: A meta-analysis approach Abstract: We conducted a meta-analysis to explore dose-response relationships for bladder and lung cancers when people are chronically exposed to low doses of arsenic. We searched electronic databases for articles published through 2010. Ten studies on bladder cancer and ingested arsenic exposure and five studies on lung cancer and ingested arsenic exposure fit our selection criteria. We also investigate the sensitivity of the absolute risk of lung and bladder cancer under different underlying prevalence measures. Males have a higher risk of bladder cancer than do females at all maximum contamination levels. The absolute risk of bladder cancer and lung cancer from ingested arsenic correlates highly with smoking rates. For a maximum contamination level of 10 µg/L, we estimate that there are about 2.91 additional bladder cancer cases per 100 000 people and, considering studies since 2000, we estimate that there are about 4.51 additional lung cancer cases per 100 000 people.",
Arsenic,2088360,"Determination of Eight Mineral Elements in Chinese Bayberry (Myrica rubra) from Zhejiang, China Abstract: ",
Arsenic,1015940,"Long-term low-level arsenic exposure is associated with poorer neuropsychological functioning: A Project FRONTIER study Abstract: Exposure to elements in groundwater (toxic or beneficial) is commonplace yet, outside of lead and mercury, little research has examined the impact of many commonly occurring environmental exposures on mental abilities during the aging process. Inorganic arsenic is a known neurotoxin that has both neurodevelopmental and neurocognitive consequences. The aim of this study was to examine the potential association between current and long-term arsenic exposure and detailed neuropsychological functioning in a sample of rural-dwelling adults and elders. Data were analyzed from 434 participants (133 men and 301 women) of Project FRONTIER, a community-based participatory research study of the epidemiology of health issues of rural-dwelling adults and elders. The results of the study showed that GIS-based groundwater arsenic exposure (current and long-term) was significantly related to poorer scores in language, visuospatial skills, and executive functioning. Additionally, long-term low-level exposure to arsenic was significantly correlated to poorer scores in global cognition, processing speed and immediate memory. The finding of a correlation between arsenic and the domains of executive functioning and memory is of critical importance as these are cognitive domains that reflect the earliest manifestations of Alzheimer's disease. Additional work is warranted given the population health implications associated with long-term low-level arsenic exposure.",
Arsenic,1252128,"Dimethylarsinic acid exposure causes accumulation of Hsp72 in cell nuclei and suppresses apoptosis in human alveolar cultured (L-132) cells Abstract: We previously found that 72-kDa heat shock protein (Hsp72) was induced and accumulated in the nuclei, together with DNA damage, in human alveolar epithelial (L-132) cells by exposure to dimethylarsinic acid (DMAA), which is a main metabolite of inorganic arsenics in mammals. In the present study, the intracellular behavior of Hsp72 was investigated during the recovery from the DNA damage induced by exposure to DMAA. L-132 cells were exposed to 10 mM DMAA for 3 h, and then incubated in DMAA-free medium. The induction of Hsp72 by exposure to DMAA reached a peak at 6-9 h after removal of DMAA. However, the cell-nuclear distribution of Hsp72 was observed until 3 h after the start of DMAA-free incubation. We further investigated the appearance of apoptosis of L-132 cells after exposure to 10 mM DMAA for 3 h. Internucleosomal DNA fragmentation and morphological changes, as criteria for the evidence of apoptosis, were observed 6-22 h after the start of DMAA-free incubation. The appearance of apoptosis was followed by the release of Hsp72 from the cell nuclei. These results suggest a possibility that the cell-nuclear Hsp72 may suppress the appearance of apoptosis in DNA-damaged cells.",
Arsenic,2149149,"Roles of YB-1 under arsenite-induced stress: Translational activation of HSP70 mRNA and control of the number of stress granules Abstract: <strong>BACKGROUND: </strong>When cells become stressed, they form stress granules (SGs) and show an increase of the molecular chaperone HSP70. The translational regulator YB-1 is a component of SGs, but it is unclear whether it contributes to the translational induction of HSP70 mRNA. Here we examined the roles of YB-1 in SG assembly and translational regulation of HSP70 mRNA under arsenite-induced stress.<br /><br /><strong>METHOD: </strong>Using arsenite-treated NG108-15 cells, we examined whether YB-1 was included in SGs with GluR2 mRNA, a target of YB-1, and investigated the interaction of YB-1 with HSP70 mRNA and its effect on translation of the mRNA. We also investigated the distribution of these mRNAs to SGs or polysomes, and evaluated the role of YB-1 in SG assembly.<br /><br /><strong>RESULTS: </strong>Arsenite treatment reduced the translation level of GluR2 mRNA; concomitantly, YB-1-bound HSP70 mRNA was increased and its translation was induced. Sucrose gradient analysis revealed that the distribution of GluR2 mRNA was shifted from heavy-sedimenting to much lighter fractions, and also to SG-containing non-polysomal fractions. Conversely, HSP70 mRNA was shifted from the non-polysomal to polysome fractions. YB-1 depletion abrogated the arsenite-responsive activation of HSP70 synthesis, but SGs harboring both mRNAs were still assembled. The number of SGs was increased by YB-1 depletion and decreased by its overexpression.<br /><br /><strong>CONCLUSION: </strong>In arsenite-treated cells, YB-1 mediates the translational activation of HSP70 mRNA and also controls the number of SGs through inhibition of their assembly.<br /><br /><strong>GENERAL SIGNIFICANCE: </strong>Under stress conditions, YB-1 exerts simultaneous but opposing actions on the regulation of translation via SGs and polysomes.",
Arsenic,1021452,"Urinary arsenic species, toenail arsenic, and arsenic intake estimates in a Michigan population with low levels of arsenic in drinking water Abstract: The large disparity between arsenic concentrations in drinking water and urine remains unexplained. This study aims to evaluate predictors of urinary arsenic in a population exposed to low concentrations (?50??g/l) of arsenic in drinking water. Urine and drinking water samples were collected from a subsample (n=343) of a population enrolled in a bladder cancer case-control study in southeastern Michigan. Total arsenic in water and arsenic species in urine were determined using ICP-MS: arsenobetaine (AsB), arsenite (As[III]), arsenate (As[V]), methylarsenic acid (MMA[V]), and dimethylarsenic acid (DMA[V]). The sum of As[III], As[V], MMA[V], and DMA[V] was denoted as SumAs. Dietary information was obtained through a self-reported food intake questionnaire. Log(10)-transformed drinking water arsenic concentration at home was a significant (P&lt;0.0001) predictor of SumAs (R(2)=0.18). Associations improved (R(2)=0.29, P&lt;0.0001) when individuals with less than 1??g/l of arsenic in drinking water were removed and further improved when analyses were applied to individuals who consumed amounts of home drinking water above the median volume (R(2)=0.40, P&lt;0.0001). A separate analysis indicated that AsB and DMA[V] were significantly correlated with fish and shellfish consumption, which may suggest that seafood intake influences DMA[V] excretion. The Spearman correlation between arsenic concentration in toenails and SumAs was 0.36 and between arsenic concentration in toenails and arsenic concentration in water was 0.42. Results show that arsenic exposure from drinking water consumption is an important determinant of urinary arsenic concentrations, even in a population exposed to relatively low levels of arsenic in drinking water, and suggest that seafood intake may influence urinary DMA[V] concentrations.",
Arsenic,744853,"Arsenite depresses poly(adp-ribosyl)ation in human skin keratinocytes and in mouse skin Abstract: Drinking arsenic-contaminated water is associated with neoplasias of the skin, lung, bladder, and possibly other sites. Previously, we demonstrated that arsenite in drinking water enhances solar ultraviolet irradiation-induced skin carcinoma in the mouse. We suggest that alterations in DNA repair and genomic stability play a role in arsenite carcinogenesis. Although DNA repair enzymes are not inhibited by arsenite, evidence suggests that poly(ADP-ribose) (PAR) synthesis is inhibited in arsenite treated cells. Poly(ADP-ribosyl)ation of proteins contributes to DNA repair and maintenance of genomic stability. Human skin keratinocytes (HaCaT) were exposed to 0.1?M sodium arsenite for different times, lysed, and levels of PAR and poly(ADP-ribose)polymerase (PARP-1) were analyzed by Western blotting. PARP- 1 protein levels increased up to 2.5 fold after 4 days exposure and remained high for at least 14 days. During this time, growth in arsenite caused decreases in total protein poly(ADP-ribosyl)ation, suggesting that arsenite inhibits PARP-1 enzyme activity. Because PARP-1 regulates its own transcription via PARP-1 auto-poly(ADPribosyl) ation, we suggest that the inhibition of PARP-1 activity by arsenite resulted in enhanced PARP-1 transcription. Arsenite?s effects on protein poly(ADP-ribosyl) ation were also demonstrated in mice. Skh1 hairless mice were given 10 mg/l (non-toxic concentration) of sodium arsenite in drinking water for 29 weeks. Immunohistochemistry of normal skin obtained at the end of the experiment showed an increased epidermal thickness and decreased level of nuclear protein poly(ADP-ribosyl)ation, compared with control mice. Our results suggest that inhibition of poly(ADP-ribosyl)ation by arsenite may contribute to arsenite-associated carcinogenesis by its effects on DNA repair, DNA-damage-signaling, and transcription. We have constructed a vector for PARP-1 RNA interference to test the role of PARP-1 in arsenite-induced cell transformation.",
Arsenic,1016820,"Modulation of aryl hydrocarbon receptor-regulated gene expression by arsenite, cadmium, and chromium Abstract: Aryl hydrocarbon receptor (AhR) ligands and heavy metals are environmental co-contaminants and their molecular interaction may disrupt the coordinated regulation of AhR-dependent phase I and II drug metabolizing enzymes. To determine the effect of heavy metals on the AhR-regulated genes: cytochrome P4501A1 (Cyp1a1), NAD(P)H: quinone oxidoreductase (QOR) and glutathione S-transferase Ya (GST Ya), murine hepatoma Hepa 1c1c7 cells were treated with increasing concentrations of As3+ (1-10 microM), Cd2+ (1-25 microM) and Cr6+ (1-25 microM) with or without the AhR ligands: 2,3,7,8-tetrachlorodibenzo-p-dioxin (0.1 nM), 3-methylcholanthrene (0.25 microM), beta-naphthoflavone (10 uM), or benzo[a]pyrene (1 microM). Our results show that AhR ligands alone and As3+ or Cd2+ alone increased the catalytic activities and mRNA levels of all AhR-regulated genes. When metals were co-administered with an AhR ligand, all three metals inhibited the induction of Cyp1a1 activity by the AhR ligands but potentiated its mRNA and protein expression. In addition, all metals enhanced QOR and GST Ya at the activity and mRNA levels but modulated their induction by AhR ligands in a concentration, metal, and AhR ligand-dependent manner. Generally, Cr6+ inhibited while As3+ and Cd2+ potentiated the induction of QOR and GST Ya activities and mRNA levels. The three metals enhanced the expression of heme oxygenase-1, which coincided with the changes in the phase I and phase II enzyme activities. These results show that the ability of metals to alter the capacity of AhR ligands to induce the bioactivating phase I and the detoxifying phase II enzymes will influence the carcinogenicity and mutagenicity of the AhR ligands.",
Arsenic,2343558,"Tannic acid and saponin for removing arsenic from brownfield soils: Mobilization, distribution and speciation Abstract: Plant biosurfactants were used for the first time to remove As and co-existing metals from brownfield soils. Tannic acid (TA), a polyphenol, and saponin (SAP), a glycoside were tested. The soil washing experiments were performed in batch conditions at constant biosurfactant concentration (3%). Both biosurfactants differed in natural pH, surface tension, critical micelle concentration and content of functional groups. After a single washing, TA (pH 3.44) more efficiently mobilized As than SAP (pH 5.44). When both biosurfactants were used at the same pH (SAP adjusted to 3.44), arsenic mobilization was improved by triple washing. The process efficiency for TA and SAP was similar, and depending on the soil sample, ranged between 50%-64%. Arsenic mobilization by TA and SAP resulted mainly from decomposition of Fe arsenates, followed by Fe3+ complexation with biosurfactants. Arsenic was efficiently released from reducible and partially from residual fractions. In all soils, As(V) was almost completely removed, whereas content of As(III) was decreased by 37%-73%. SAP and TA might be used potentially to remove As from contaminated soils.",
Arsenic,1021991,"Mercury and other mining-related contaminants in ospreys along the Upper Clark Fork River, Montana, USA Abstract: We investigated links between mining-related contaminants in river sediment and their occurrence in nestling ospreys (Pandion haliaetus) in the Clark Fork River Basin, Montana, USA. Blood and feather samples from 111 osprey chicks were collected during 4 years from nests along river sections with greatly different sediment concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), and mercury (Hg). No significant differences between river sections were found among Zn (3,150 ± 160 ?g L(-1)) and Cd (&lt;5 ?g L(-1)) concentrations in blood. Cu, Pb, and As concentrations in blood were significantly increased in chicks from the most contaminated river sections (mean values of 298, 8.9, and 100 ?g L(-1), respectively). Cu, Zn, and Pb concentrations increased significantly during a year of above-average river runoff combined with high suspended sediment loads in rivers. Total Hg concentrations in blood and feathers were highly correlated and depended on the geographic locations of the nests. The lowest blood concentrations of Hg were observed in the most upstream river section (mean 151 ?g L(-1)) where total sediment concentrations were increased (0.80 mg kg(-1)). River sections with intermediate blood concentrations (mean 206 and 303 ?g L(-1)) were associated with low to intermediate sediment concentrations (0.058 and 0.46 mg kg(-1)). The highest concentrations of Hg in ospreys (mean 548 ?g L(-1)) were observed downstream from a contaminated tributary (1-4 mg kg(-1) in sediment). In river sections with lower Hg concentrations in sediment, there was a negative correlation between blood Hg concentration and chick mass, presumably due to high deposition rates into growing feathers. This relationship was absent in sections of high Hg exposure. Osprey blood and feathers are suitable for monitoring Hg in aquatic ecosystems; however, responses of As, Cd, Cu, Pb, and Zn are more subtle.",
Arsenic,1021474,"Exposure to arsenic in drinking water is associated with increased prevalence of diabetes: A cross-sectional study in the Zimapán and Lagunera regions in Mexico Abstract: <strong>BACKGROUND: </strong>Human exposures to inorganic arsenic (iAs) have been linked to an increased risk of diabetes mellitus. Recent laboratory studies showed that methylated trivalent metabolites of iAs may play key roles in the diabetogenic effects of iAs. Our study examined associations between chronic exposure to iAs in drinking water, metabolism of iAs, and prevalence of diabetes in arsenicosis-endemic areas of Mexico.<br /><br /><strong>METHODS: </strong>We used fasting blood glucose (FBG), fasting plasma insulin (FPI), oral glucose tolerance test (OGTT), glycated hemoglobin (HbA1c), and insulin resistance (HOMA-IR) to characterize diabetic individuals. Arsenic levels in drinking water and urine were determined to estimate exposure to iAs. Urinary concentrations of iAs and its trivalent and pentavalent methylated metabolites were measured to assess iAs metabolism. Associations between diabetes and iAs exposure or urinary metabolites of iAs were estimated by logistic regression with adjustment for age, sex, hypertension and obesity.<br /><br /><strong>RESULTS: </strong>The prevalence of diabetes was positively associated with iAs in drinking water (OR 1.13 per 10 ppb, p &lt; 0.01) and with the concentration of dimethylarsinite (DMAsIII) in urine (OR 1.24 per inter-quartile range, p = 0.05). Notably, FPI and HOMA-IR were negatively associated with iAs exposure (? -2.08 and -1.64, respectively, p &lt; 0.01), suggesting that the mechanisms of iAs-induced diabetes differ from those underlying type-2 diabetes, which is typically characterized by insulin resistance.<br /><br /><strong>CONCLUSIONS: </strong>Our study confirms a previously reported, but frequently questioned, association between exposure to iAs and diabetes, and is the first to link the risk of diabetes to the production of one of the most toxic metabolites of iAs, DMAsIII.",
Arsenic,2149264,"Tanshinone I activates the Nrf2-dependent antioxidant response and protects against As(III)-induced lung inflammation in vitro and in vivo Abstract: AIMS: The NF-E2 p45-related factor 2 (Nrf2) signaling pathway regulates the cellular antioxidant response and activation of Nrf2 has recently been shown to limit tissue damage from exposure to environmental toxicants, including As(III). In an attempt to identify improved molecular agents for systemic protection against environmental insults, we have focused on the identification of novel medicinal plant-derived Nrf2 activators. RESULTS: Tanshinones [tanshinone I (T-I), tanshinone IIA, dihydrotanshinone, cryptotanshinone], phenanthrenequinone-based redox therapeutics derived from the medicinal herb Salvia miltiorrhiza, have been tested as experimental therapeutics for Nrf2-dependent cytoprotection. Using a dual luciferase reporter assay overexpressing wild-type or mutant Kelch-like ECH-associated protein-1 (Keap1), we demonstrate that T-I is a potent Keap1-C151-dependent Nrf2 activator that stabilizes Nrf2 by hindering its ubiquitination. In human bronchial epithelial cells exposed to As(III), T-I displays pronounced cytoprotective activity with upregulation of Nrf2-orchestrated gene expression. In Nrf2 wild-type mice, systemic administration of T-I attenuates As(III) induced inflammatory lung damage, a protective effect not observed in Nrf2 knockout mice. INNOVATION: Tanshinones have been identified as a novel class of Nrf2-inducers for antioxidant tissue protection in an in vivo As(III) inhalation model, that is relevant to low doses of environmental exposure. CONCLUSION: T-I represents a prototype Nrf2-activator that displays cytoprotective activity upon systemic administration targeting lung damage originating from environmental insults. T-I based Nrf2-directed systemic intervention may provide therapeutic benefit in protecting other organs against environmental insults.",
Arsenic,1508716,"Correlation of respiratory symptoms and spirometric lung patterns in a rural community setting, Sindh, Pakistan: A cross sectional survey Abstract: <strong>BACKGROUND: </strong>Symptom-based questionnaires can be a cost effective tool enabling identification and diagnosis of patients with respiratory illnesses in resource limited setting. This study aimed to determine the correlation of respiratory symptoms and spirometric lung patterns and validity of ATS respiratory questionnaire in a rural community setting.<br /><br /><strong>METHODS: </strong>This cross sectional survey was conducted between January - March 2009 on a sample of 200 adults selected from two villages of district Khairpur, Sindh, Pakistan. A modified version of the American thoracic society division of lung disease questionnaire was used to record the presence of respiratory symptoms. Predicted lung volumes i.e. forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and their ratio (FEV1/FVC) were recorded using portable spirometer.<br /><br /><strong>RESULTS: </strong>In the study sample there were 91 (45.5%) males and 109 (54.5%) females with overall mean age of 34 years (±11.69). Predominant respiratory symptom was phlegm (19%) followed by cough (17.5%), wheeze (14%) and dyspnea (10.5%). Prevalence of physician diagnosed and self-reported asthma was 5.5% and 9.5% respectively. Frequency of obstructive pattern on spirometry was 28.72% and that of restrictive pattern was 19.68%. After adjustment for age, gender, socioeconomic status, spoken dialect, education, smoking status, height, weight and arsenic in drinking water, FVC was significantly reduced for phlegm (OR 3.01; 95% CI: 1.14 - 7.94), wheeze (OR 7.22; 95% CI: 2.52 - 20.67) and shortness of breath (OR 4.91; 95% CI: 1.57 - 15.36); and FEV1 was significantly reduced for cough (OR 2.69; 95% CI: 1.12 - 6.43), phlegm (OR 3.01; 95% CI: 1.26 - 7.16) and wheeze (OR 10.77; 95% CI: 3.45 - 33.6). Presence of respiratory symptoms was significantly associated with restrictive and/or obstructive patterns after controlling for confounders. Similar findings were observed through linear regression where respiratory symptoms were found to be significantly associated with decrements in lung volumes. Specificity and positive predictive values were found to be higher for all the symptoms compared to sensitivity and negative predictive values.<br /><br /><strong>CONCLUSION: </strong>Symptoms based respiratory questionnaires are a valuable tool for screening of respiratory symptoms in resource poor, rural community setting.",
Arsenic,1020337,"Induction of genotoxic damage is not correlated with the ability to methylate arsenite in vitro in the leukocytes of four mammalian species Abstract: Arsenic is a natural drinking water contaminant that impacts the health of large populations of people throughout the world; however, the mode or mechanism by which arsenic induces cancer is unclear. In a series of in vitro studies, we exposed leukocytes from humans, mice, rats, and guinea pigs to a range of sodium arsenite concentrations to determine whether the lymphocytes from these species showed differential sensitivity to the induction of micronuclei (MN) assessed in cytochalasin B-induced binucleate cells. We also determined the capacity of the leukocytes to methylate arsenic by measuring the production of MMA [monomethylarsinic acid (MMA(V)) and monomethylarsonous acid (MMA(III))] and DMA [dimethylarsinic acid (DMA(V)) and dimethylarsonous acid (DMA(III))]. The results indicate that cells treated for 2 hr at the G(0) stage of the cell cycle with sodium arsenite showed only very small to negligible increases in MN after mitogenic stimulation. Treatment of actively cycling cells produced induction of MN with increasing arsenite concentration, with the human, rat, and mouse lymphocytes being much more sensitive to MN induction than those of the guinea pig. These data gave an excellent fit to a linear model. The leukocytes of all four species, including the guinea pig (a species previously thought not to methylate arsenic), were able to methylate arsenic, but there was no clear correlation between the ability to methylate arsenic and the induction of MN.",
Arsenic,2347566,"Total arsenic screening prior to fractionation enhances clinical utility and test utilization in the assessment of arsenic toxicity Abstract: <strong>OBJECTIVES: </strong>The objective was to evaluate the utility of a screen with reflex-to-fractionation testing compared with direct-to-fractionation testing for suspected toxic exposure.<br /><br /><strong>METHODS: </strong>This study was based on a retrospective data analysis of urine arsenic results from previously tested samples (n = 12,960). Total urine arsenic by inductively coupled plasma mass spectrometry was used as a screening method to identify elevated arsenic concentrations. Arsenic fractionation was the speciation assay to differentiate toxic and benign arsenic species.<br /><br /><strong>RESULTS: </strong>Screening samples based on total arsenic concentration resulted in less than 10% of samples requiring arsenic fractionation, with a final positivity rate of less than 1% for toxic arsenic. Samples with fractionation ordered directly had a positivity rate for toxic arsenic of 3.3%. The overall positivity rate for exposure to toxic arsenic was less than 1%.<br /><br /><strong>CONCLUSIONS: </strong>A total arsenic screen before fractionation reduces the number of samples requiring fractionation by more than 91%, supporting the use of a screen with a reflex-to-fractionation approach for urine arsenic.",
Arsenic,1350066,"Regulation of erythrocyte Na-K-2Cl cotransport by threonine phosphorylation Abstract: A method is described to measure threonine phosphorylation of the Na-K-2Cl cotransporter in ferret erythrocytes using readily available antibodies. We show that most, if not all, cotransporter in these cells is NKCC1, and this was immunoprecipitated with T4. Cotransport rate, measured as 86Rb influx, correlates well with threonine phosphorylation of T4-immunoprecipitated protein. The cotransporter effects large fluxes and is significantly phosphorylated in cells under control conditions. Transport and phosphorylation increase 2.5- to 3-fold when cells are treated with calyculin A or Na+ arsenite. Both fall to 60% control when cell [Mg2+] is reduced below micromolar or when cells are treated with the kinase inhibitors, 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine or staurosporine. Importantly, these latter interventions do not abolish either phosphorylation or transport suggesting that a phosphorylated form of the cotransporter is responsible for residual fluxes. Our experiments suggest protein phosphatase 1 (PrP-1) is extremely active in these cells and dephosphorylates key regulatory threonine residues on the cotransporter. Examination of the effects of kinase inhibition after cells have been treated with high concentrations of calyculin indicates that residual PrP-1 activity is capable of rapidly dephosphorylating the cotransporter. Experiments on cotransporter precipitation with microcystin sepharose suggest that PrP-1 binds to a phosphorylated form of the cotransporter.",
Arsenic,2088490,"Cytotoxic and genotoxic effects of metal(oid)s bioactivated in rocket leaves (Eruca vesicaria subsp. sativa Miller) Abstract: Rocket is an important source of essential elements. However, it may also accumulate toxic elements such as metal(oids). The objectives of the present work were (i) to study the uptake of arsenic, lead, cadmium and zinc in rocket grown in contaminated soils, (ii) to establish the genotoxic and cytotoxic activities of this vegetable material, and (iii) to study the modulator role of the glucosinolate and metal contents in the genotoxic/cytotoxic activities. Lead, cadmium and zinc leaf concentrations in our study were over the concentrations allowed by the statutory limit set for metal(oid) contents in vegetables. The accessions were non genotoxic at the different concentrations studied, although one of the accessions showed the highest mutation rates doubling those of negative control. The cytotoxicity assays with HL60 human leukaemia cells showed that the tumouricide activities of rocket leaves decreased with the increasing of metal(oid) concentrations and also with the decreasing of glucosinolate concentrations in their tissues. An interaction between metal(oid)s and glucosinolate degradation products contained in rocket leaves is suggested as the main modulator agents of the biological activity of the plants grown in metal-contaminated soils.",
Arsenic,1019656,The death of Napoleon Bonaparte: a critical review of the cause Abstract: ,
Arsenic,2337187,"Adsorption of arsenic by activated carbon, calcium alginate and their composite beads Abstract: The present investigation deals with preparation of three different adsorbent materials namely; potassium hydroxide activated carbon based apricot stone (C), calcium alginate beads (G) and calcium alginate/activated carbon composite beads (GC) were used for the removal of arsenic. The prepared adsorbent materials were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), N2-adsorption at -196°C and point of zero charge. From the obtained results, it was found that the porosity, surface area and total pore volume of the adsorbent material C&gt;GC&gt;G respectively, however, the G adsorbent has more acidic function group than the other adsorbents. The influence of pH, time, temperature and initial concentration of arsenic(V) were studied and optimized. GC exhibits the maximum As(V) adsorption (66.7mg/g at 30°C). The adsorption of arsenic ions was observed to follow pseudo-second order mechanism as well as the thermodynamic parameters confirm also the endothermic spontaneous and a physisorption process.",
Arsenic,1034706,Atomic absorption determination of nanogram quantities of arsenic in biological media Abstract: HEEP COPYRIGHT: BIOL ABS. An improved method for the preparation of organic samples and a sensitive procedure for As analysis using a single-beam atomic absorption spectrophotometer is described.,
Arsenic,1028667,"Arsenite exposure compromises early embryonic development in the Golden hamster Abstract: The toxicity of arsenite to 8-cell stage hamster embryos was evaluated. Females were superovulated and mated; embryos were collected and grown for 72 h in culture medium containing vehicle control, 25, 50, 250, 500, or 750 nM arsenite. Morphological observations were taken at 0 and 24h increments. A TUNEL assay was used for determining DNA damage. Survival was expressed by the ability to undergo zona escape. The control group had 78% survival and no evidence of deformities. Embryos in the 25, 50 and 250 nM groups had survival rates of 63%, 55% and 27%, respectively. Arsenite exposure caused total embryo lethality, major deformities, complete failure to undergo zona lysis, and significantly higher number of cells with fragmented DNA in embryos at the 500 and 750 nM concentrations. The study underscores the sensitivity of preimplantation stage embryos to the presence of even relatively small amounts of arsenic in luminal fluid.",
Arsenic,2088545,"Association of urinary arsenic, heavy metal, and phthalate concentrations with food allergy in adults: National Health and Nutrition Examination Survey, 2005-2006 Abstract: ",
Arsenic,627176,"Microbial metabolite of dimethylarsinic acid is highly toxic and genotoxic Abstract: Dimethylarsinic acid [DMA, (CH3)2AsO(OH)] causes cancer in the urinary bladder of rats. However, its mechanism of cancer or the ultimate carcinogenic form is not yet known. Rats administered dimethylarsinic acid excrete three unknown arsenic compounds (termed M-1, M-2, and M-3) in urine or feces, and these compounds are presumed to be produced by intestinal bacteria. Escherichia coli A3-6 isolated from a rat yielded two unknown arsenic compounds (M-2 and M-3) from dimethylarsinic acid and M-1 from trimethylarsine oxide (TMAO) in the presence of cysteine (Cys). Contents of M-2 and M-3 varied with cysteine concentration. The cytotoxicity and genotoxicity of the bacteria-free solution of dimethylarsinic acid or trimethylarsine oxide metabolized by E. coli A3-6 were studied using V79 cells. Dimethylarsinic acid (1 mM) metabolized by E. coli A3-6 in the presence of cysteine (1 mM) was highly cytotoxic (50% survival reduction concentration; 2.1 AM As) in V79 cells, and the toxic substance appeared to be M-2. The metabolite solution (at 2.5–10 AM total As) induced c-mitosis and tetraploids, and caused mitotic arrest, since it increased mitotic cells at the cytotoxic dose. The metabolite solution also significantly increased sister chromatid exchange (SCE) and chromosomal aberrations, most of which were chromatid gaps and chromatid breaks. A3-6 converted 96.1% of trimethylarsine oxide to M-1 in the presence of cysteine. This metabolite solution did not exhibit cytotoxicity or genotoxicity. The reported M-2 concentration in urine of rats administered levels of DMA via drinking water known to cause bladder tumors was sufficient to exhibit cytotoxic and genotoxic effects in urinary bladder. Thus, we hypothesize that intestinal bacteria play an important role in carcinogenicity of dimethylarsinic acid.",
Arsenic,735028,"Arsenite enhances the benzo[a]pyrene diol epoxide (BPDE)-induced mutagenesis with no marked effect on repair of BPDE-DNA adducts in human lung cells Abstract: Arsenite effects on the benzo[a]pyrene diol epoxide (BPDE)-DNA adduct-induced mutation were evaluated in three human lung cell-lines--A549 (wild-type p53), WI38-VA13 (p53 inhibited by SV40 large-T antigen), and H1299 (p53-null)--by using the pSP189 shuttle vector, which carries a mutation target supF gene. Arsenite alone had no significant effect on the spontaneous supF mutation. BPDE modification of pSP189 enhanced the mutation rates of supF 4.37-fold, 2.96-fold, and 1.95-fold for A549, WI38-VA13, and H1299, respectively. Arsenite potentiated the BPDE-induced mutation rates of supF 2.30-fold, 2.31-fold, and 2.35-fold in A549, WI38-VA13, and H1299, respectively. These results suggest that arsenite potentiates the BPDE-induced supF mutation via a p53-independent mechanism. By using the host cell reactivation assay, we evaluated arsenite effect on repair of BPDE-DNA adducts. We found that the arsenite treatments resulting in relative survival rates 65% had no significant effect on repair of BPDE-DNA adducts, indicating that p53 status did not significantly affect the repair of BPDE-DNA adducts. This study reveals that arsenite enhances the BPDE-DNA adduct-induced mutagenesis with no marked effect on repair of BPDE-DNA adducts, suggesting that arsenic may act as a co-mutagen to promote the development of human lung cancer.",
Arsenic,1340125,"Arsenite oxidation in Ancylobacter dichloromethanicus As3-1b strain: Detection of genes involved in arsenite oxidation and CO2 fixation Abstract: The aim of this study was to characterize a facultative chemolithotrophic arsenite-oxidizing bacterium by evaluating the growth and the rate of arsenite oxidation and to investigate the genetic determinants for arsenic resistance and CO(2) fixation. The strain under study, Ancylobacter dichloromethanicus As3-1b, in a minimal medium containing 3 mM of arsenite as electron donor and 6 mM of CO(2)-bicarbonate as the C source, has a doubling time (t(d)) of 8.1 h. Growth and arsenite oxidation were significantly enhanced by the presence of 0.01 % yeast extract, decreasing the t(d) to 4.3 h. The strain carried arsenite oxidase (aioA) gene highly similar to those of previously reported arsenite-oxidizing Alpha-proteobacteria. The RuBisCO Type-I (cbbL) gene was amplified and sequenced too, underscoring the ability of As3-1b to carry out autotrophic As(III) oxidation. The results suggest that A. dichloromethanicus As3-1b can be a good candidate for the oxidation of arsenite in polluted waters or groundwaters.",
Arsenic,657860,"Arsenic concentrations in well water and risk of bladder and kidney cancer in Finland Abstract: We assessed the levels of arsenic in drilled wells in Finland and studied the association of arsenic exposure with the risk of bladder and kidney cancers. The study persons were selected from a register-based cohort of all Finns who had lived at an address outside the municipal drinking-water system during 1967-1980 (n = 144,627). The final study population consisted of 61 bladder cancer cases and 49 kidney cancer cases diagnosed between 1981 and 1995, as well as an age- and sex-balanced random sample of 275 subjects (reference cohort). Water samples were obtained from the wells used by the study population at least during 1967-1980. The total arsenic concentrations in the wells of the reference cohort were low (median = 0.1 microg/L; maximum = 64 microg/L), and 1% exceeded 10 microg/L. Arsenic exposure was estimated as arsenic concentration in the well, daily dose, and cumulative dose of arsenic. None of the exposure indicators was statistically significantly associated with the risk of kidney cancer. Bladder cancer tended to be associated with arsenic concentration and daily dose during the third to ninth years prior to the cancer diagnosis; the risk ratios for arsenic concentration categories 0.1-0.5 and [Greater/equal to] 0.5 microg/L relative to the category with < 0.1 microg/L were 1.53 [95% confidence interval (CI), 0.75-3.09] and 2.44 (CI, 1.11-5.37), respectively. In spite of very low exposure levels, we found some evidence of an association between arsenic and bladder cancer risk. More studies are needed to confirm the possible association between arsenic and bladder cancer risk at such low exposure levels.",
Arsenic,1509332,"Distribution of Arsenic, Antimony, and Thallium in Soil in Kavadarci and its Surroundings, Republic of Macedonia Abstract: The aim of this study is to present a spatial distribution of As, Sb, and Tl in topsoil and subsoil in the Kavadarci region, Republic of Macedonia. In total, 344 soil samples were collected from 172 locations (05 cm and 2030 cm) in an area of 360 km2. ICP-MS was applied for the determination of the invesgated elements. It was found that the highest contents of As, Sb, and Tl were on Holocene alluvium of the river Crna Reka, where average concentrations exceeded the average of the total investigated area by two times for As, three for Tl, and more than five times for Sb. The enrichment of the Holocene alluvium of the river Crna Reka is supposed to be a consequence of natural erosion from Allchar mine deposits on Kozuf Mountain and also from mining activities in the past.",
Arsenic,710808,"Arsenic down-regulates the expression of Camk4, an important gene related to cerebellar LTD in mice Abstract: To elucidate the molecular mechanism of arsenic (As) on motor learning and memory, concentration of As in cerebellar tissue of mice exposed to 1 ppm and 4 ppm As(2)O(3) subchronically was determined by ICP-MS, neurobehavioral changes associated with memory was examined by the Morris Water Maze test, and the critical gene expression profiles related to the Creb-dependent phase of cerebellar long-term depression (LTD) were analyzed by GeneChip. Our results showed the increased level of As concentration in cerebellar tissue of the exposed mice in a dose-response manner, longer escape latency in the experimental group than controls and the down-regulated expression of Ca(2+)/calmodulin dependent protein kinase IV (Camk4), a very important regulator in the LTD pathway. We further analyzed the influence of As on cerebellar Camk4 expression by Western blot. The quantity of Camk4 band in the group exposed to 4 ppm As(2)O(3) significantly decreased compared to the control group, agreeing well with gene microarray results. It is indicated that the accumulated As induced learning and memory impairment and impeded the Camk4 expression. Therefore, the Camk4 may be target of As-induced neurotoxicity. Furthermore, the intervention of antioxidants taurine or vitamin C did not prevent Camk4 from down-regulation, indicating that the down-regulation of Camk4 expression by As may be via an oxidation-independent way.",
Arsenic,628236,"Chronic oral exposure to inorganic arsenate interferes with methylation status of p16INK4a and RASSF1A and induces lung cancer in A/J mice Abstract: Although inorganic arsenate (iAs(V)) or arsenite (iAs(III)) is clearly a human carcinogen, it has been difficult to produce tumors in rodents. In the present study, we orally administered iAs(V) to A/J mice to examine arsenic carcinogenicity in rodent. A/J mice (male, n = 120) assigned to four groups were given drinking water containing 0, 1, 10, and 100 ppm iAs(V) for 18 months. At the end of experiment, the complete lungs were removed and used for examining histopathology and extracting RNA and DNA. Epigenetic effects of iAs(V) on DNA methylation patterns of p16INK4a and RASSF1A genes were determined by methylation-specific polymerase chain reaction. Changes of p16INK4a and RASSF1A at mRNA and protein levels were examined by reverse transcriptase-polymerase chain reaction and immunohistochemistry. Arsenic was accumulated dose dependently in the lung tissues of iAs(V)-exposed mice. Increase in lung tumor number and lung tumor size was observed in iAs(V)-exposed mice compared to the control. Histopathological examination showed that the rate of poorly differentiated lung adenocarcinoma was much higher in iAs(V)-exposed mice than in the control. Methylation rates appeared to be higher in a dose-related tendency in lung tumors from iAs(V)-exposed mice compared to the control. Lower or loss of p16INK4a and RASSF1A expression was found in lung tumors from iAs(V)-exposed mice, compared to that in nontumor lung tissues from both control and iAs(V)-exposed mice, and this reduced or lost expression was in accordance with hypermethylation of the genes. In conclusion, iAs(V) exposure increased lung tumor incidence and multiplicity in A/J mice. Epigenetic changes of tumor suppressor genes such as p16INK4a and RASSF1A are involved in the iAs(V)-induced lung carcinogenesis.",
Arsenic,1020552,"The effect of arsenic mitigation interventions on disease burden in Bangladesh Abstract: Many interventions have been advocated to mitigate the impact of arsenic contamination of drinking water in Bangladesh. However, there are few data on the true magnitude of arsenic-related disease in Bangladesh nationally. There has also been little consideration given to possible adverse effects of such interventions, in particular, diarrheal disease. The purpose of this study was to estimate and compare the likely impacts of arsenic mitigation interventions on both arsenic-related disease and water-borne infectious disease. We found that arsenic-related disease currently results in 9,136 deaths per year and 174,174 disability-adjusted life years (DALYs; undiscounted) lost per year in those exposed to arsenic concentrations &gt; 50 microg/L. This constitutes 0.3% of the total disease burden in Bangladesh in terms of undiscounted DALYs. We found intervention to be of overall benefit in reducing disease burden in most scenarios examined, but the concomitant increase in water-related infectious disease significantly reduced the potential benefits gained from intervention. A minimum reduction in arsenic-related DALYs of 77% was necessary before intervention achieved any reduction in net disease burden. This is assuming that interventions were provided to those exposed to &gt; 50 microg/L and would concomitantly result in a 20% increase in water-related infectious disease in those without access to adequate sanitation. Intervention appears to be justified for those populations exposed to high levels of arsenic, but it must be based on exposure levels and on the effectiveness of interventions not only in reducing arsenic but in minimizing risk of water-related infections. Key words: arsenic/adverse effects, Bangladesh, burden of disease, diarrhea, risk assessment, water pollutants, water supply.",
Arsenic,1797833,"Arsanilic acid causes apoptosis and oxidative stress in rat kidney epithelial cells (NRK-52e cells) by the activation of the caspase-9 and -3 signaling pathway Abstract: Arsenic exists widely in rock, water and air, and arsanilic acid (also known as aminophenyl arsenic acid) is an organoarsenic compound and has been used as feed additives. Organoarsenic compounds in foodstuff cause adverse effects, including acute and chronic toxicity, in animals and humans. However, little is known about the cellular toxicity and mechanisms of organic arsenic on the kidney. In this study, we explored the toxicity and molecular mechanisms of arsanilic acid on rat kidney epithelial cells (NRK-52e cells). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that arsanilic acid inhibited the proliferation of rat NRK-52e cells in a dose-dependent manner, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay and flow cytometry revealed that arsanilic acid induced cellular apoptosis in NRK-52e cells. Fluorescence spectrophotometer displayed that arsanilic acid caused a loss of mitochondrial transmembrane potential (MMP) of NRK-52e cells, but enhanced reactive oxygen species level of these cells. Notably, trolox, a water-soluble derivative of vitamin E, protected NRK-52e cells against MMP loss and apoptosis caused by arsanilic acid. Western blots with caspase inhibitors further indicated that arsanilic acid increased expression of active caspase-3 and -9 in NRK-52e cells. Collectively, these results suggest that arsanilic acid causes apoptosis and oxidative stress in rat kidney epithelial cells through activation of the caspase-9 and -3 signaling pathway. This study thus provides a novel insight into molecular mechanisms by which arsanilic acid has adverse cytotoxicity on renal tubular epithelial cells.",
Arsenic,1354456,"Specificity and uniqueness of endothelial cell stress responses Abstract: The mammalian response to cellular stresses often involves upregulation of certain stress proteins. This response is usually neither cell nor stress specific and sometimes results in cross-protection to other stresses. Endothelial cell (EC) hypoxia-associated proteins (HAP) are a unique set of stress proteins upregulated by exposure to environmental hypoxia. In the present study, the specificity of stress protein upregulation was assessed and any potential cross-protection was evaluated using DNA strand break analysis. EC cultured in 21% or 3% oxygen were exposed to single and combined cellular stresses (0% oxygen, reoxygenation, glucose deprivation, sodium arsenite, heat, or hydrogen peroxide). Although EC can upregulate various stress proteins, the HAP are specifically upregulated only with hypoxia and offer no cross-protection against other cellular stresses. Moreover, induction of other stress proteins does not alter the induction of the HAP or the effects of hypoxia in cultured EC. Thus EC display a unique specificity in regard to the stimulus for upregulation of stress proteins and are distinct from other cell types thus far examined.",
Arsenic,710887,"Chronic exposure to arsenic in the drinking water alters the expression of immune response genes in mouse lung Abstract: Chronic exposure to drinking water arsenic is a significant worldwide environmental health concern. Exposure to As is associated with an increased risk of lung disease, which may make it a unique toxicant, because lung toxicity is usually associated with inhalation rather than ingestion.<br /><br /> The goal of this study was to examine mRNA and protein expression changes in the lungs of mice exposed chronically to environmentally relevant concentrations of As in the food or drinking water, specifically examining the hypothesis that As may preferentially affect gene and protein expression related to immune function as part of its mechanism of toxicant action.<br /><br /> C57BL/6J mice fed a casein-based AIN-76A defined diet were exposed to 10 or 100 ppb As in drinking water or food for 5-6 weeks.<br /><br /> Whole genome transcriptome profiling of animal lungs revealed significant alterations in the expression of many genes with functions in cell adhesion and migration, channels, receptors, differentiation and proliferation, and, most strikingly, aspects of the innate immune response. Confirmation of mRNA and protein expression changes in key genes of this response revealed that genes for interleukin 1beta, interleukin 1 receptor, a number of toll-like receptors, and several cytokines and cytokine receptors were significantly altered in the lungs of As-exposed mice.<br /><br /> These findings indicate that chronic low-dose As exposure at the current U.S. drinking-water standard can elicit effects on the regulation of innate immunity, which may contribute to altered disease risk, particularly in lung.",
Arsenic,1465765,"Increased childhood mortality and arsenic in drinking water in Matlab, Bangladesh: A population-based cohort study Abstract: <strong>BACKGROUND: </strong>Arsenic in drinking water was associated with increased risk of all-cause, cancer, and cardiovascular death in adults. However, the extent to which exposure is related to all-cause and deaths from cancer and cardiovascular condition in young age is unknown. Therefore, we prospectively assessed whether long-term and recent arsenic exposures are associated with all-cause and cancer and cardiovascular mortalities in Bangladeshi childhood population.<br /><br /><strong>METHODS AND FINDINGS: </strong>We assembled a cohort of 58406 children aged 5-18 years from the Health and Demographic Surveillance System of icddrb in Bangladesh and followed during 2003-2010. There were 185 non-accidental deaths registered in-about 0.4 million person-years of observation. We calculated hazard ratios for cause-specific death in relation to exposure at baseline (µg/L), time-weighted lifetime average (µg/L) and cumulative concentration (µg-years/L). After adjusting covariates, hazard ratios (HRs) for all-cause childhood deaths comparing lifetime average exposure 10-50.0, 50.1-150.0, 150.1-300.0 and ?300.1µg/L were 1.37 (95% confidence interval [CI], 0.74-2.57), 1.44 (95% CI, 0.88-2.38), 1.22 (95% CI, 0.75-1.98) and 1.88 (95% CI, 1.14-3.10) respectively. Significant increased risk was also observed for baseline (P for trend?=?0.023) and cumulative exposure categories (P for trend?=?0.036). Girls had higher mortality risk compared to boys (HR for girls 1.79, 1.21, 1.64, 2.31; HR for boys 0.52, 0.53, 1.14, 0.99) in relation to baseline exposure. For all cancers and cardiovascular deaths combined, multivariable adjusted HRs amounted to 1.53 (95% CI 0.51-4.57); 1.29 (95% CI 0.43-3.87); 2.18 (95%CI 1.15-4.16) for 10.0-50.0, 50.1-150.0, and ?150.1, comparing lowest exposure as reference (P for trend?=?0.009). Adolescents had higher mortality risk compared to children (HRs?=?1.53, 95% CI 1.03-2.28 vs. HRs?=?1.30, 95% CI 0.78-2.17).<br /><br /><strong>CONCLUSIONS: </strong>Arsenic exposure was associated with substantial increased risk of deaths at young age from all-cause, and cancers and cardiovascular conditions. Girls and adolescents (12-18 years) had higher risk compared to boys and child.",
Arsenic,1019458,Arsenic in well water supplies in Saskatchewan Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM ARSENIC IN WELL WATER SUPPLIES IN SASKATCHEWANYRESEARCH ARTICLE TOXICOLOGY ECOTOXICOLOGY ARSENIC CARCINOGEN POLLUTANT TOXIN DRINKING WATER QUALITY GUIDELINES ARSENIC(V) EPA WHO HEALTH RISKS WASTE MANAGEMENT ARSENICAL PESTICIDES ATMOSPHERIC DEPOSITION POLLUTION GOVERNMENT AGENCY COMPANY SASKATCHEWAN CANADA,
Arsenic,656633,"Stress-specific signatures: expression profiling of p53 wild-type and -null human cells Abstract: Gene expression responses of human cell lines exposed to a diverse set of stress agents were compared by cDNA microarray hybridization. The B-lymphoblastoid cell line TK6 (p53 wild-type) and its p53-null derivative, NH32, were treated in parallel to facilitate investigation of p53-dependent responses. RNA was extracted 4 h after the beginning of treatment when no notable decrease in cell viability was evident in the cultures. Gene expression signatures were defined that discriminated between four broad general mechanisms of stress agents: Non-DNA-damaging stresses (heat shock, osmotic shock, and 12-O-tetradecanoylphorbol 13-acetate), agents causing mainly oxidative stress (arsenite and hydrogen peroxide), ionizing radiations (neutron and gamma-ray exposures), and other DNA-damaging agents (ultraviolet radiation, methyl methanesulfonate, adriamycin, camptothecin, and cis-Platinum(II)diammine dichloride (cisplatin)). Within this data set, non-DNA-damaging stresses could be discriminated from all DNA-damaging stresses, and profiles for individual agents were also defined. While DNA-damaging stresses showed a strong p53-dependent element in their responses, no discernible p53-dependent responses were triggered by the non-DNA-damaging stresses. A set of 16 genes did exhibit a robust p53-dependent pattern of induction in response to all nine DNA-damaging agents, however.",
Arsenic,1070445,"Arsenic fractionation in mine spoils 10 years after aided phytostabilization Abstract: Aided phytostabilization using a combination of compost, zerovalent iron grit and coal fly ash (CZA) amendments and revegetation effectively promoted the biological recovery of mining spoils generated at a gold mine in Portugal. Selective dissolution of spoil samples in combination with solid phase characterization using microbeam X-ray absorption near edge structure (?XANES) spectroscopy and microbeam X-ray fluorescence (?XRF) mapping were used to assess As associations in spoils ten years after CZA treatment. The results show that As preferentially associates with poorly crystalline Fe-oxyhydroxides as opposed to crystalline Fe-(oxyhydr)oxide phases. The crystalline Fe(III)-phases dominated in the treated spoil and exceeded those of the untreated spoil three-fold, but only 2.6-6.8% of total As was associated with this fraction. Correlation maps of As:Fe reveal that As in the CZA-treated spoils is primarily contained in surface coatings as precipitates and sorbates. Arsenic binding with poorly crystalline Fe-oxyhydroxides did not inhibit As uptake by plants.",
Arsenic,2347606,"Metals in horseshoe crab eggs from Delaware Bay, USA: Temporal patterns from 1993 to 2012 Abstract: The health of horseshoe crab (Limulus polyphemus) eggs is important not only to maintain horseshoe crab populations, but because they are a resource for higher trophic levels, such as fish and shorebirds. We examined the concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the eggs of horseshoe crabs from Delaware Bay (between New Jersey and Delaware, USA) in 1993, 1994, 1995, 1999, 2000, and 2012 to determine if there were significant temporal changes and if levels appear to pose a health risk to the crabs themselves, or to predators that consume them. All metal levels declined in horseshoe crab eggs between 1994 and 2012, although the declines were much less consistent for lead and chromium than that for mercury and cadmium. Levels of contaminants found in these eggs are well below those known to cause adverse effects in the crabs themselves or to organisms that consume them, such as migrating shorebirds.",
Arsenic,1018822,"Apoptosis induction by arsenic: mechanisms of action and possible clinical applications for treating therapy-resistant cancers Abstract: Arsenic, a known carcinogen, may be useful in cancer treatment. Arsenic may be effective in counteracting drug resistance because it appears to induce apoptosis in tumor cells independently of p53 activation, thereby allowing it to be directed against p53-defective cancers. The role of MAP kinases in arsenic-induced apoptosis in tumor cells is important and may be influenced by reactive oxygen species or glutathione. This review focuses on recent findings from this and other laboratories regarding the mechanism(s) of arsenic-induced apoptosis in tumor cells and considers their relevance in the clinical treatment of therapy-resistant cancers. Copyright 2000 Harcourt Publishers Ltd.",
Arsenic,1383525,"Photodamage and Skin Cancer among Paraquat Workers Abstract: A relationship between bipyridine (366187) exposure during the manufacture of paraquat and photodamage and skin cancer was reported. Exposed workers from 28 paraquat factories in Taiwan were examined for skin lesions. Photographs were taken for objective comparison of all lesions, which were graded on a scale of increasing severity from one to three. From a total of 242 exposed workers, 133 workers had gradable lesions, 13 had severe grade three lesions, five workers had ungradable lesions, and 86 workers had no apparent lesions. Biopsies were taken from ten of 11 affected workers with representative lesions to yield 23 pathological specimens. Histological examination of the specimens showed that the selected workers had actinic keratosis (AK). Four developed squamous cell carcinoma (SCC) or in-situ SCC after 6 to 14 months of bipyridine exposure. Of the lesions biopsied, three were solar lentigo, 11 were AK, three were SCC in-situ coexisting with AK, and three were SCC. Questionnaires completed by each worker showed no history of other risk factors, such as previous irradiation, exposure to arsenic, or skin cancer, among the affected workers. Two thirds of the paraquat factories produced paraquat from bipyridines after centrifugation and crystallization in open areas. Workers involved in this process were considered heavily exposed. A trend for association between severity of lesions and heavy exposure was determined by Mantel extension. The odds ratios for developing grades zero, one, two, or three lesions were calculated as 1, 3.9, 3.2 and 85.7, respectively. The authors conclude that the strong correlation between photodamage and bipyridine exposure may be due to a synergistic role of a solar effect and bipyridine exposure.",
Arsenic,628710,"Association between chronic exposure to arsenic and slow nerve conduction velocity among adolescents in Taiwan Abstract: The association between chronic exposure to arsenic and peripheral neuropathy has been controversial in previous studies, which may be due to the influence of factors, such as age, gender, chronic diseases, occupational injuries, and arsenic exposure. To clarify the question of this association, a cross-sectional study was designed. In total, 130 junior high school students aged 12-14 years were included and exami-ned for the motor and sensory nerve conduction velocity of peripheral nerves in their right-upper and lower limbs. Concentrations of arsenic in well-water and history of drinking well-water were retrieved from a baseline database created in 1991. After adjustment for gender and height, a significant odds ratio of 2.9 (95% confidence interval [CI] 1.1-7.5) was observed for the development of slow nerve conduction velocity of the sural sensory action potential (SAP) among the study subjects with a cumulative arsenic dosage of >100.0 mg. In addition, a borderline statistical significance with odds ratio of 7.8 (95% CI 1.001-69.5) for the development of slow nerve conduction velocity of sural SAP was also observed among the study subjects who drank well-water containing arsenic concentrations of >50.0 ?g/L and with a cumulative arsenic dosage of >100.0 mg. The study found that chronic exposure to arsenic might induce peripheral neuropathy. It also found that the slowing of the nerve conduction velocity of sural SAP might be an early marker of chronic arsenic neuropathy.",
Arsenic,1031948,"Angiosarcoma of the spleen: A report of two cases and review of the literature Abstract: Results of the ultrastructural study of one of two cases of splenic angiosarcoma established the blood vessel origin of this tumor. Fifty-three previously reported cases were reviewed. None of the 55 patients had a history of exposure to thorium dioxide, vinyl chloride, or arsenic, which are known to be associated with hepatic angiosarcoma and other tumors. A comparison of the splenic and hepatic angiosarcomas showed that tumors not associated with exogenous material frequently involve the spleen and liver simultaneously, and that tumors associated with thorium dioxide, vinyl chloride, or arsenic commonly involve the liver with sparing of the spleen.",
Arsenic,2278228,"Archaeometallurgical studies of Bronze Age objects from the Romanian cultural heritage Abstract: This paper reports the chemical composition of some ancient metallic objects dated to the Bronze Age period and found on Romanian territory. Preliminary ED-XRF measurements were performed on cleaned areas of artefacts, while the nuclear microprobe experiments were conducted on tiny fragments detached from the same zones. The identified trace-elements led to some speculations about the employed metallurgical procedures and raw materials. Thus, the chemical composition of the Early Bronze Age dagger found at Ocni?a suggests its manufacturing by smelting a mixture of copper and arsenic ores, while the Late Bronze Age artefacts have compositional patterns supporting the idea of connections and exchanges between the ancient populations living along the Danube river.",
Arsenic,2088477,"Depth-resolved abundance and diversity of arsenite-oxidizing bacteria in the groundwater of Beimen, a blackfoot disease endemic area of southwestern Taiwan Abstract: The role of arsenite oxidizers in natural attenuation of arsenic pollution necessitates studies on their abundance and diversity in arsenic-contaminated aquifers. In this study, most probable number-polymerase chain reaction (MPN-PCR) and denaturing gradient gel electrophoresis (DGGE) was applied to monitor depth-wise abundance and diversity of aerobic arsenite oxidizers in arsenic-enriched groundwater of Beimen, southwestern Taiwan. The results revealed that the abundance of arsenite oxidizers ranged from 0.04 to 0.22, and the lowest ratio was observed in the most arsenic-enriched and comparatively more reduced groundwater (depth 200 m) of Beimen 1. The highest ratio was observed in the less arsenic-enriched and less reduced groundwater (depth 60 m) of Beimen 2B. DGGE profiles showed a shift in diversity of arsenite oxidizers, consisting of members of the Betaproteobacteria (61%), Alphaproteobacteria (28%) and Gammaproteobacteria (11%), depending on mainly arsenic concentration and redox level in groundwater. Groundwater with the lowest arsenic and highest dissolved oxygen at Beimen 2B harbored 78% of the arsenite oxidizers communities, while groundwater with the highest arsenic and lowest dissolved oxygen at Beimen 1 and Beimen-Jinhu harbored 17 and 22% of arsenite oxidizers communities, respectively. Pseudomonas sp. was found only in groundwater containing high arsenic at Beimen 1 and Beimen-Jinhu, while arsenite oxidizers belonging to Alpha- and Betaproteobacteria were dominated in groundwater containing low arsenic.",
Arsenic,627518,"Glutathione as a cellular defence against arsenite toxicity in cultured Chinese hamster ovary cells Abstract: The cytotoxic effect of arsenite seems to be inversely related to the intracellular glutathione (GSH) content, and GSH seems to facilitate the metabolism of arsenic in cell. Arsenite is also known to induce chromosome aberration, to enhance the cytotoxicity and clastogenicity of ultraviolet (UV) light, and to inhibit UV-induced DNA repair. We have investigated whether these toxic effects of arsenite and the cellular arsenic content are also modulated by the intracellular GSH. A 2-h pretreatment of the cultured ovary (CHO) cells with GSH reduced the clastogenicity and cytotoxicity of arsenite. The enhancing effects of arsenite on chromosome aberrations and cell destruction induced by UV were also reduced by a 2-h pretreatment with GSH. The inhibitory effect of arsenite on the strand-break rejoining during UV-induced DNA repair was reduced by GSH pretreatment and was enhanced by pretreatment with buthionine sulfoximine, which is known to deplete the cellular GSH. The cellular arsenic content was reduced by GSH pretreatment and increased by buthionine sulfoximine pretreatment. GSH given before or simultaneously with arsenite, effectively reduced the clastogenicity and coclastogenicity of arsenite. GSH given after treatment with arsenite decreased the cellular arsenic content, and increased the cell survival, but did not reduce the clastogenicity or the coclastogenicity of arsenite.",
Arsenic,1023515,"Pilot-scale demonstration of phytofiltration for treatment of arsenic in New Mexico drinking water Abstract: Arsenic contamination of drinking water poses serious health risks to millions of people worldwide. To reduce such risks, the United States Environmental Protection Agency recently lowered the Maximum Contaminant Level for arsenic in drinking water from 50 to 10 microgL(-1). The majority of water systems requiring compliance are small systems that serve less than 10,000 people. Current technologies used to clean arsenic-contaminated water have significant drawbacks, particularly for small treatment systems. In this pilot-scale demonstration, we investigated the use of arsenic-hyperaccumulating ferns to remove arsenic from drinking water using a continuous flow phytofiltration system. Over the course of a 3-month demonstration period, the system consistently produced water having an arsenic concentration less than the detection limit of 2 microgL(-1), at flow rates as high as 1900 L day(-1) for a total treated water volume of approximately 60,000 L. Our results demonstrate that phytofiltration provides the basis for a solar-powered hydroponic technique to enable small-scale cleanup of arsenic-contaminated drinking water.",
Arsenic,1355439,"CADMIUM ACCUMULATION IN THE ROOTLESS MACROPHYTE WOLFFIA GLOBOSA AND ITS POTENTIAL FOR PHYTOREMEDIATION Abstract: Cadmium (Cd) pollution around the world is a serious issue demanding acceptable solutions, one of which is phytoremediation that is both cost-effective and eco-friendly. Removal of Cd from contaminated water using plants with high growth rates and sufficient Cd accumulation abilities could be an appropriate choice. Here, we investigated a potential Cd accumulator, Wolffia, a rootless duckweed with high growth rate. Cd uptake, accumulation, tolerance, and phytofiltration ability by Wolffia globosa were examined. Furthermore, the effects of arsenic (As) on Cd uptake and phytofiltration by W. globosa were also studied. Cd uptake kinetics showed a linear pattern and a hyperbolic pattern without a plateau in lower (0-2 microM) and higher (0-200 microM) Cd concentration ranges, respectively, suggesting rapid Cd uptake by W. globosa Cd accumulation ability by W. globosa was higher at Cd concentrations &lt; 10 microM than at &gt;10 microM. All the five species of Wolffia exposed to I microM Cd for 5 days accumulated &gt; 500 mg Cd kg(-1) DW. Ten gram fresh W. globosa could diminish almost all the Cd (2 microM) in a 200 mL solution. This enormous accumulation ability was mostly due to passive adsorption of Cd by the apoplast. Arsenic had no significant effect on Cd uptake and phytofiltration. The fresh fronds also showed a great As extracting ability. The results indicated that Wolffia is a strong Cd accumulator and has great Cd phytoremediation potential. Therefore, this plant can be used in fresh aquatic environments co-contaminated by low-levels of Cd and As.",
Arsenic,1579259,"Chitosan-transition metal ions complexes for selective arsenic(V) preconcentration Abstract: Chitosan is naturally occurring bio-polymer having strong affinity towards transition metal ions. Chitosan complexed with transition metal ions takes up inorganic arsenic anions from aqueous medium. In present work, As(V) sorption in the chitosan complexed with different metal ions like Cu(II), Fe(III), La(III), Mo(VI) and Zr(IV) were studied. Sorptions of As(V) in CuS embedded chitosan, (3-aminopropyl) triethoxysilane (APTS) embedded chitosan, epichlorohydrin (ECH) crosslinked chitosan and pristine chitosan were also studied. (74)As radiotracer was prepared specifically for As(V) sorption studies by irradiation of natural germanium target with 18 MeV proton beam. The sorption studies indicated that Fe(III) and La(III) complexed with chitosan sorbed 95 ± 2% As(V) from aqueous samples in the pH range of 3-9. However, Fe(III)-chitosan showed better sorption efficiency (91 ± 2%) for As(V) from seawater than La(III)-chitosan (80 ± 2%). Therefore, Fe(III)-chitosan was selected to prepare the self-supported membrane and poly(propylene) fibrous matrix supported sorbent. The experimental As(V) sorption capacities of the fibrous and self-supported Fe(III)-chitosan sorbents were found to be 51 and 109 mg g(-1), respectively. These materials were characterized by XRD, SEM and EDXRF, and used for preconcentration of As(V) in aqueous media like tap water, ground water and seawater. To quantify the As(V) preconcentrated in Fe(III)-chitosan, the samples were subjected to instrumental neutron activation analysis (INAA) using reactor neutrons. As(V) separations were carried out using a two compartments permeation cell for the self-supported membrane and flow cell using the fibrous sorbent. The total preconcentration of arsenic content was also explored by converting As(III) to As(V).",
Arsenic,1018963,"Potentiation of arsenic-induced cytotoxicity by sulfur amino acid deprivation (SAAD) through activation of ERK1/2, p38 kinase and JNK1: the distinct role of JNK1 in SAAD-potentiated mercury toxicity Abstract: Sulfur amino acid deficiency occurs in certain pathophysiological situations (e.g. protein-calorie malnutrition). Previous studies revealed that sulfur amino acid deprivation (SAAD) activated MAP kinases and potentiated cadmium-induced cytotoxicity by activation of ERK1/2 in conjunction with p38 kinase or JNK. The present study was designed to determine susceptibility of cells to a variety of heavy metals in combination with SAAD. Viability was assessed in H4IIE cells treated with sodium arsenite, mercuric chloride, sodium selenite, lead acetate, chromium trioxide or manganese chloride. SAAD potentiated the cytotoxicity of H4IIE cells by arsenic or mercury (i.e. EC50, 19 and 5 microM in SAAD vs. 401 and 42 microM in control medium, respectively). TUNEL assays revealed that the potentiated arsenic or mercury toxicity involved apoptotic cell death. Lead or selenite moderately elicited cell death, which was not enhanced by SAAD. Chromium or manganese caused no significant cytotoxicity. Treatment of cells with U0126 [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] an ERK1/2 inhibitor or SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] a p38 kinase inhibitor effectively prevented SAAD-potentiated arsenic toxicity. The potentiated arsenic toxicity was also inhibited in cells stably expressing a dominant negative mutant of c-Jun N-terminal kinase 1 [JNK1(-)]. The inhibitors of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 kinase failed to prevent mercury-induced toxicity enhanced by SAAD. JNK1(-) cells were minimally susceptible to mercury in SAAD medium. These results demonstrated that SAAD potentiated cytotoxicity induced by arsenic or mercury and that activation of ERK1/2, p38 kinase and JNK1 was responsible for the potentiated arsenic toxicity, whereas the mercury toxicity enhanced by SAAD was mediated with the activity of JNK1.",
Arsenic,1677569,"Bioavailability and toxicity of arsenic in maize (Zea mays L.) grown in contaminated soils Abstract: The growth of maize (Zea mays L.), hybrid Valentina, was compared in two types of contaminated soil substrates (Ochre and Heap) with different arsenic (As) concentration originating from an old mining area in Slovakia. Although the total As concentration in Heap soil was 2.6 times lower than in Ochre soil (90 and 237 mg kg(-1), respectively), plants grown in Heap soil accumulated more As in their tissues (shoot and root As concentration being 4 and 5.5 times higher, respectively) and were markedly smaller, which produced significantly less biomass and flowered later in comparison with Ochre soil grown plants.",
Arsenic,1337345,"Metal interaction with redox regulation: An integrating concept in metal carcinogenesis? Abstract: The carcinogenicity of cadmium, arsenic, and chromium(VI) compounds has been recognized for some decades. However, the underlying molecular mechanisms seem to be complex and are not completely understood at present. Although, with the exception of chromium(VI), direct DNA damage seems to be of minor importance, interactions with DNA repair processes, tumor suppressor functions, and signal transduction pathways have been described in diverse biological systems. In addition to the induction of damage to cellular macromolecules by reactive oxygen species, the interference with cellular redox regulation by reaction with redox-sensitive protein domains or amino acids may provide one plausible mechanism involved in metal carcinogenicity. Consequences are the distortion of zinc-binding structures and the activation or inactivation of redox-regulated signal transduction pathways, provoking metal-induced genomic instability. Nevertheless, the relevance of the respective mechanisms depends on the actual metal or metal species under consideration and more research is needed to further strengthen this hypothesis.",
Arsenic,1519033,"The genome sequence of the hydrocarbon degrading Acinetobacter venetianus VE-C3 Abstract: Here we report the genome sequence of Acinetobacter venetianus VE-C3, a strain isolated from the Venice Lagoon and known to be able to degrade n-alkanes. Post sequencing analyses revealed that this strain is relatively distantly related to the other Acinetobacter strains completely sequenced so far as shown by phylogenetic analysis and pangenome analysis (1285 genes shared with all the other Acinetobacter genomes sequenced so far). A. venetianus VE-C3 possesses a wide range of determinants whose molecular functions are probably related to the survival in a strongly impacted ecological niche. Among them, genes probably involved in the metabolism of long chain n-alkanes and in the resistance to toxic metals (e.g. arsenic, cadmium, cobalt and zinc) were found. Genes belonging to these processes were found both on the chromosome and on plasmids. Also, our analysis documented one of the possible genetic bases underlying the strategy adopted by A. venetianus VE-C3 for the adhesion to oil fuel droplets, which could account for the differences existing in this process with other A. venetianus strains. Finally, the presence of a number of DNA mobilization-related genes (i.e. transposases, integrases, resolvases) strongly suggests an important role played by horizontal gene transfer in shaping the genome of A. venetianus VE-C3 and in its adaptation to its special ecological niche.",
Arsenic,1794729,"A Review of Molybdenum Adsorption in Soils/Bed Sediments: Speciation, Mechanism, and Model Applications Abstract: ",
Arsenic,737144,"Arsenic-related chromosomal alterations in bladder cancer Abstract: Previous studies have demonstrated that ingestion of arsenic in drinking water is a strong risk factor for several forms of cancer, including bladder cancer. It is not known whether arsenic-related cancers are genetically similar to cancers in unexposed individuals or what mechanisms of carcinogenesis may underlie their formation. This study was designed to compare chromosomal alterations in bladder cancers of arsenic-exposed individuals to provide insight into the mechanism of how arsenic may induce or promote cancer.<br /><br /> A case-case study was conducted in Argentina and Chile examining chromosomal alterations in bladder tumor DNA in 123 patients who had been exposed to arsenic in their drinking water. Patients were placed into one of four arsenic exposure categories according to their average 5-year peak arsenic exposure. Patients were also classified as ever smokers or never smokers. Comparative genomic hybridization was used to identify chromosomal alterations throughout the genome. All statistical tests were two-sided.<br /><br /> The total number of chromosomal alterations was higher in individuals exposed to higher arsenic levels (5.7 +/- 5.1, 5.6 +/- 5.1, 7.3 +/- 7.4, and 9.1 +/- 6.5 [mean +/- standard deviation] chromosomal alterations per tumor with increasing arsenic exposure; P(trend) =.02, adjusted for stage and grade). The trend was stronger in high-grade (G2-G3) tumors (6.3 +/- 5.5, 8.3 +/- 4.7, 10.3 +/- 7.8, and 10.5 +/- 6.4 alterations per tumor; P(trend) =.01) than it was in low-grade (G1) tumors (3.5 +/- 3.1, 1.1 +/- 1.1, 2.5 +/- 2.5, and 3.6 +/- 3.2 alterations per tumor; P(trend) =.79). The mean number of chromosomal alterations also increased with tumor stage and grade (P(trend)&lt;.001) independently of arsenic exposure but was not associated with smoking history. Deletion of part or all of chromosome 17p (P(trend)&lt;.001) showed the strongest association with arsenic exposure.<br /><br /> Bladder tumors in patients with higher levels of arsenic exposure showed higher levels of chromosomal instability. Most of the chromosomal alterations associated with arsenic exposure were also associated with tumor stage and grade, raising the possibility that bladder tumors from arsenic-exposed patients may behave more aggressively than tumors from unexposed patients.",
Arsenic,1070362,"An in vitro assessment of bioaccessibility of arsenicals in rice and the use of this estimate within a probabilistic exposure model Abstract: In this study, an in vitro synthetic gastrointestinal extraction protocol was used to estimate bioaccessibility of different arsenicals present in 17 rice samples of various grain types that were collected across the United States. The across matrix average for total arsenic was 209?ng/g±153 (\[xmacr]±2?). The bioaccessibility estimate produced an across matrix average of 61%±19 (\[xmacr]±2?). The across matrix average concentrations of inorganic arsenic (iAs) and dimethylarsinic acid (DMA) were 81?ng/g±67.7 and 41?ng/g±58.1 (\[xmacr]±2?), respectively. This distribution of iAs concentrations in rice was combined with the distribution of consumption patterns (from WWEIA) in a Stochastic Human Exposure and Dose Simulator model to estimate population-based exposures. The mean consumption rate for the population as a whole was 15.7?g per day resulting in a 0.98??g iAs per day exposure. The mean consumption rate for children 1-2 years old was 7?g per day resulting in a 0.48??g iAs per day exposure. Presystemic biotransformation of DMA in rice was examined using an in vitro assay containing the anaerobic microbiota of mouse cecum. This assay indicated that DMA extracted from the rice was converted to dimethylthioarsinic acid, although a second oxygen-sulfur exchange to produce DMDTA was not observed.Journal of Exposure Science and Environmental Epidemiology advance online publication, 2 May 2012; doi:10.1038/jes.2012.24.",
Arsenic,1015746,"Korea National Survey for Environmental Pollutants in the Human Body 2008: Heavy metals in the blood or urine of the Korean population Abstract: BACKGROUND: Recently, there have been several nationwide episodes involving imported toys contaminated with toxic metals and environmental hormones. In addition, cadmium intoxication has occurred due to soil contamination with cadmium from abandoned metal mines. OBJECTIVES: To investigate the distribution, extent and factors influencing the levels of toxic metals in the blood or urine of the Korean general population over twenty years of age, we studied the blood or urine concentrations of heavy metals in a representative sample of 5087 Koreans in 2008. METHODS: Multiple biological substrates were collected from each participant to determine the most suitable samples for an environmental health survey system. Information regarding exposure conditions of all subjects was collected by questionnaire-based interviews. RESULTS: The geometric means of the blood lead, mercury and manganese levels were 19.1, 3.23 and 10.8?g/L, respectively. The geometric means of urinary arsenic and cadmium concentrations were 43.5 and 0.65?g/L, respectively. Blood mercury and urinary arsenic levels in the Korean general population were significantly higher than in European and American populations. CONCLUSIONS: The higher levels of blood mercury and urinary arsenic could be explained by the greater seafood consumption among the Korean population. This biomonitoring study of blood or urine heavy metals in the Korean general population provides important reference data stratified by demographic and lifestyle factors that will be useful for the ongoing surveillance of environmental exposure of Koreans to toxic metals.",
Arsenic,1579312,"Determination of arsenic species in edible periwinkles (Littorina littorea) by HPLC-ICPMS and XAS along a contamination gradient Abstract: Arsenic is naturally found in the tissues of marine animals, usually as the non-toxic arsenical arsenobetaine, but exposure to elevated arsenic concentrations in the environment may alter the arsenic species distribution within tissues of the organism. This study examined the arsenic species in the tissues of the marine periwinkle (Littorina littorea) along an arsenic concentration gradient in the sediment. The arsenicals in L. littorea were examined using the complementary analytical methods high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICPMS) and X-ray absorption spectroscopy (XAS). Total arsenic concentrations in the periwinkle tissues ranged from 56 to 840mg·kg(-1) dry weight (equivalent to 13 to 190mg·kg(-1) wet weight). Inorganic arsenicals were found to be positively correlated with total arsenic concentrations (R(2)=0.993) and reached 600mg·kg(-1) dry weight, the highest reported to date in marine organisms. These high inorganic arsenic concentrations within this low trophic organism pose a potential toxicological risk to higher trophic consumers.",
Arsenic,501814,"Quercetin administration during chelation therapy protects arsenic-induced oxidative stress in mice Abstract: We studied the efficacy of quercetin and a thiol chelating agent, monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA) either individually or in combination against arsenic-induced oxidative stress and mobilization of metal in mouse. Animals were chronically exposed to 25 ppm arsenite as sodium arsenite in drinking water for 12 months followed by treatment with MiADMSA (0.2 mmol/kg, orally), quercetin (0.2 mmol, orally) either alone or in combination, once daily for 5 consecutive days. Arsenic exposure led to a significant depletion of blood delta-aminolevulinic acid dehydratase (ALAD) activity, glutathione, white (WBC) and red blood cell (RBC) counts, and an increase in platelet levels while significantly increasing the level of reactive oxygen species (in RBCs). Hepatic reduced catalase (CAT) and glutathione peroxidase activities showed a depletion, whereas thiobarbituric acid reactive substances (TBARS) levels increased on arsenic exposure indicating arsenite-induced oxidative stress in blood and liver. Kidney CAT activity showed a depletion, whereas TBARS levels increased on arsenic exposure. These biochemical changes were accompanied by an increase in blood, liver, and kidney arsenic concentration. Treatment with MiADMSA was effective in increasing ALAD activity, whereas quercetin was ineffective when given alone. Quercetin when co-administered with MiADMSA also provided no additional beneficial effect on blood ALAD activity but significantly brought altered platelet counts nearer to the normal value. In contrast, administration of quercetin alone provided significant beneficial effects on hepatic oxidative stress and kidney TBARS levels. Renal biochemical variables remained insensitive to arsenic and any of the treatments. Interestingly, combined administration of quercetin with MiADMSA had a remarkable effect in depleting total arsenic concentration from blood and soft tissues. These results lead us to conclude that quercetin administration during chelation treatment had some beneficial effects particularly on the protection of inhibited blood ALAD activity and depletion of arsenic level from target organs. The study supports our earlier conclusion that a co-administration of an antioxidant particularly flavonoids more beneficial than monotherapy with the chelating agents to achieve optimal effects of chelation in arsenite toxicity.",
Arsenic,1597400,"Effect of water management on cadmium and arsenic accumulation by rice (Oryza sativa L.) with different metal accumulation capacities Abstract: Purpose Water management affects the bioavailability of cadmium (Cd) and arsenic (As) in the soil and hence their accumulation in rice grains and grain yields. However, Cd and As show opposite responses to soil water content, but information, particularly on irrigation, is missing on a field scale. The purpose of the present study was therefore to find a water management regime that can lower accumulation of both Cd and As in grain without yield loss. Materials and methods Two rice (Oryza sativa L.) cultivars, A16 and A159, with different grain Cd accumulation capacities were employed in field plot experiments with four water management regimes comprising aerobic, intermittent, conventional practice and flooded. The dynamics of Cd and As bioavailability in the soil and Cd and As concentrations in roots, straw and grains were determined at the early tillering, full tillering, panicle initiation, filling and maturity stages of crop growth. Results and discussion The lower water content regimes (aerobic and intermittent) mostly led to higher soil HCl-extractable Cd than the higher soil water content regimes (conventional and flooded). HCl-extractable As in contrast was favoured by the higher soil water content treatments. Conventional and flooded irrigation accordingly gave higher plant As concentrations but lower Cd compared to aerobic and intermittent irrigation. Cd concentrations in roots and straw of both varieties increased with growth stage, especially in aerobic and intermittent regimes, while As concentrations in plants showed little change or a slight decrease. As the water irrigation volume increased from aerobic to flooded, brown rice Cd decreased from 1.15 to 0.02 mg?kg?1 in cultivar A16 and from 1.60 to 0.05 mg?kg?1 in cultivar A159, whereas brown rice As increased. Aerobic and flooded treatments produced approximately 10–20 % lower grain yields than intermittent and conventional treatments. Cultivars with low Cd accumulation capacity show higher brown rice grain As than those with high Cd uptake capacity. Conclusions Of the four water management regimes, the conventional irrigation method (flooding maintained until full tillering followed by intermittent irrigation) ensured high yield with low Cd and As in the brown rice and so remains the recommended irrigation regime.",
Arsenic,2149196,"Naturally occurring arsenic in terrestrial geothermal systems of western Anatolia, Turkey: Potential role in contamination of freshwater resources Abstract: Arsenic (As) contamination in terrestrial geothermal systems has been identified in many countries worldwide. Concentrations higher than 0.01 mg/L are detrimental to human health. We examined potential consequences for As contamination of freshwater resources based on hydrogeochemical investigations of geothermal waters in deep wells and hot springs collected from western Anatolia, Turkey. We analyzed samples for major ions and trace element concentrations. Temperature of geothermal waters in deep wells showed extreme ranges (40 and 230°C), while, temperature of hot spring fluids was up to 90°C. The Piper plot illustrated two dominant water types: Na-HCO3- type for geothermal waters in deep wells and Ca-HCO3- type for hot spring fluids. Arsenic concentration ranged from 0.03 to 1.5 mg/L. Dominance of reduced As species, i.e., As(III), was observed in our samples. The Eh value ranged between -250 and 119 mV, which suggests diverse geochemical conditions. Some of the measured trace elements were found above the World Health Organization guidelines and Turkish national safe drinking water limits. The variation in pH (range: 6.4-9.3) and As in geothermal waters suggest mixing with groundwater. Mixing of geothermal waters is primarily responsible for contamination of freshwater resources and making them unsuitable for drinking or irrigation.",
Arsenic,1354625,"Environmental arsenic and skin toxicity Abstract: We report here a follow-up conducted on 36 participants from a community which received drinking water containing arsenic, 22 of whom had high arsenic body burden in 1977. Two of the 36 showed signs of keratosis, but most participants revealed no history of other skin diseases.",
Arsenic,1016077,"A cultural practice of drinking realgar wine leading to elevated urinary arsenic and its potential health risk Abstract: Toasting friends and family with realgar wines and painting children's foreheads and limbs with the leftover realgar/alcohol slurries is an important customary ritual during the Dragon Boat Festival (DBF); a Chinese national holiday and ancient feast day celebrated throughout Asia. Realgar is an arsenic sulfide mineral, and source of highly toxic inorganic arsenic. Despite the long history of realgar use during the DBF, associated risk to human health by arsenic ingestion or percutaneous adsorption is unknown. To address this urine samples were collected from a cohort of volunteers who were partaking in the DBF festivities. The total concentration of arsenic in the wine consumed was 70 mg L?¹ with all the arsenic found to be inorganic. Total arsenic concentrations in adult urine reached a maximum of ca. 550 ?g L?¹ (mean 220.2 ?g L?¹) after 16 h post-ingestion of realgar wine, while face painting caused arsenic levels in children's urine to soar to 100 ?g L?¹ (mean 85.3 ?g L?¹) 40 h after the initial paint application. The average concentration of inorganic arsenic in the urine of realgar wine drinkers on average doubled 16 h after drinking, although this was not permanent and levels subsided after 28 h. As would be expected in young children, the proportions of organic arsenic in the urine remained high throughout the 88-h monitoring period. However, even when arsenic concentrations in the urine peaked at 40 h after paint application, concentrations in the urine only declined slightly thereafter, suggesting pronounced longer term dermal accumulation and penetration of arsenic. Drinking wines blended with realgar or using realgar based paints on children does result in the significant absorption of arsenic and therefore presents a potentially serious and currently unquantified health risk.",
Arsenic,628047,"Role of the alkali labile sites, reactive oxygen species and antioxidants in DNA damage induced by methylated trivalent metabolites of inorganic arsenic Abstract: In the last decade arsenic metabolism has become an important matter of discussion. Methylation of inorganic arsenic (iAs) to monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) is considered to decrease arsenic toxicity. However, in addition to these pentavalent metabolites, the trivalent metabolites monomethylarsonous (MMA(III)) and dimethylarsinous acid (DMA(III)) have been identified recently as intermediates in the metabolic pathway of arsenic in cultured human cells. To examine the role of oxidative damage in the generation of DNA strand breaks by methylated trivalent arsenic metabolites, we treated human lymphocytes with both metabolites at non-cytotoxic concentrations. We further tested whether these effects are sensitive to modulation by the antioxidants ascorbate (Vitamin C) and selenomethionine (Se-Met). Both trivalent metabolites produced oxidative stress related DNA damage, consisting of single strand breaks and alkali-labile sites, with MMA(III) being more potent at low concentrations than DMA(III). Neither MMA(III) nor DMA(III) induced DNA-double strand breaks. The oxidative stress response profiles of the metabolites were parallel as determined by lipid peroxidation induction. MMA(III) induced peroxidation from the lowest concentration tested, while effects of DMA(III) were apparent only at concentrations above 10 muM. The antioxidant Se-Met exhibited a more pronounced inhibition of trivalent arsenic metabolite-induced oxidative-DNA damage than did vitamin C. The present findings suggest that DNA damage by methylated trivalent metabolites at non-cytotoxic concentrations may be mediated by a mix of reactive oxygen and nitrogen oxidized species.",
Arsenic,1519165,"Thallium, arsenic, and mercury contamination of soil near the world's largest and longest-operating tungsten mine Abstract: Little is known about soil thallium contamination near tungsten (W) mines. This study investigated thallium, arsenic, and mercury contents and enrichment in agricultural soils near the world’s largest and longest-operating W mine in China. Results show that the long-term W mining significantly elevated Tl from 0.77 to 1.61 mg·kg-1 and As from 7.54 to 22.64 mg·kg-1, with enrichment factors of 2.0 (1.4 to 3.7) and 2.9 (1.5 to 7.2), respectively. Hg contents were similar at the contaminated site (0.16 mg·kg-1) and control site (0.19 mg·kg-1), but were two to three times higher than the soil background content of Jianxi province. Thus, Hg contamination in the soil probably was mainly caused by coal and petrol burning instead of W mining.",
Arsenic,1614968,"Dynamic changes in radial oxygen loss and iron plaque formation and their effects on Cd and As accumulation in rice (Oryza sativa L.) Abstract: Temporal variations and correlations between radial oxygen loss (ROL), iron (Fe) plaque formation, cadmium (Cd) and arsenic (As) accumulation were investigated in two rice cultivars at four different growth stages based upon soil pot and deoxygenated solution experiments. The results showed that there were significant differences in ROL (1.1-16 ?mol O2 plant(-1) h(-1)), Fe plaque formation (4,097-36,056 mg kg(-1)), Cd and As in root tissues (Cd 77-162 mg kg(-1); As 49-199 mg kg(-1)) and Fe plaque (Cd 0.4-24 mg kg(-1); As 185-1,396 mg kg(-1)) between these growth stages. ROL and Fe plaque increased dramatically from tillering to ear emergence stages and then were much reduced at the grain-filling stage. Furthermore, significantly positive correlations were detected between ROL and concentrations of Fe, Cd and As in Fe plaque. Our study indicates that increased Fe plaque forms on rice roots at the ear emergence stage due to the increased ROL. This stage could therefore be an important period to limit the transfer and distribution of Cd and As in rice plants when growing in soils contaminated with these toxic elements.",
Arsenic,1017352,"Pleurotus florida lectin normalizes duration dependent hepatic oxidative stress responses caused by arsenic in rat Abstract: Natural contamination of arsenic in ground water is a major health problem throughout the World. It is one of the most hazardous substances in the environment known to cause toxicity in multiple organs via oxidative stress. The molecular basis for arsenic toxicity involves direct or indirect damage to protein, lipid and DNA. Various studies have focused on the possible toxic effects of arsenic on membrane components and its correlation with oxidative damage. The present study was aimed to mitigation of arsenic induced hepatic oxidative stress by dietary modulation using of mushroom lectin in rats. Animals were divided into four groups; the first group was used as control. Groups 2, 3 and 4 were arsenic (20ppm) exposed through drinking water, arsenic exposed plus oral ascorbic acid (25mg/kg body weight) and arsenic exposed plus oral mushroom lectin (150mg/kg body weight) respectively for a period of 12 weeks. We observed significant alterations in the antioxidant enzymes, oxidative stress intermediates and SOD(2) gene expression profile on arsenic exposure. These alterations were restored by co-administration of Pleurotus florida lectin which was as potent as standard antioxidant viz. ascorbic acid. The findings of the experiment suggested that P. florida lectin has capability of modulating arsenic mediated toxic effects and could be helpful in ameliorating them.",
Arsenic,627830,"Environmental arsenic exposure and urinary 8-OHdG in Arizona and Sonora Abstract: Although at high levels arsenic exposure is associated with increased cancer incidence, information on the health effects of lower exposure levels is limited. The objective of this study was to determine whether arsenic at concentrations below 40 microg/L in drinking water is associated with increased urinary 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of DNA oxidative damage and repair. Urine samples were collected from 73 nonsmoking adults residing in two communities in Arizona (mean tap water arsenic (microg/L) 4.0 +/- 2.3 and 20.3 +/- 3.7), and 51 subjects in four communities in Sonora, Mexico (mean tap water arsenic (microg/L) ranging from 4.8 +/- 0.1 to 33.3 +/- 0.6). Although urinary arsenic concentration increased with higher exposure in tap water, urinary 8-OHdG concentration did not differ by community within Arizona or Sonora, and was not associated with urinary arsenic concentration. At the exposure levels evaluated in this study, drinking water arsenic was not associated with increased DNA oxidation as measured by urinary 8-OHdG.",
Arsenic,1519032,"Soil chemistry and pollution study of a closed landfill site at Ampar Tenang, Selangor, Malaysia Abstract: A total of 20 landfills are located in State of Selangor, Malaysia. This includes the Ampar Tenang landfill site, which was closed on 26 January 2010. It was reported that the landfill has been upgraded to a level I type of sanitary classification. However, the dumpsite area is not being covered according to the classification. In addition, municipal solid waste was dumped directly on top of the unlined natural alluvium formation. This does not only contaminate surface and subsurface soils, but also initiates the potential risk of groundwater pollution. Based on previous studies, the Ampar Tenang soil has been proven to no longer be capable of preventing pollution migration. In this study, metal concentrations of soil samples up to 30 m depth were analyzed based on statistical analysis. It is very significant because research of this type has not been carried out before. The subsurface soils were significantly polluted by arsenic (As), lead (Pb), iron (Fe), copper (Cu) and aluminium (Al). As and Pb exceeded the safe limit values of 5.90 mg/kg and 31.00 mg/kg, respectively, based on Provincial Sediment Quality Guidelines for Metals and the Interim Sediment Quality Values. Furthermore, only Cu concentrations showed a significantly decreasing trend with increasing depth. Most metals were found on clay-type soils based on the cluster analysis method. Moreover, the analysis also differentiates two clusters: cluster I-Pb, As, zinc, Cu, manganese, calcium, sodium, magnesium, potassium and Fe; cluster II-Al. Different clustering may suggest a different contamination source of metals.",
Arsenic,2347636,"Spectroscopic vibrations of austinite (CaZnAsO4?OH) and its mineral structure: Implications for identification of secondary arsenic-containing mineral Abstract: Austinite (CaZnAsO4?OH) is a unique secondary mineral in arsenic-contaminated mine wastes. The infrared and Raman spectroscopies were used to characterize the austenite vibrations. The IR bands at 369, 790 and 416cm(-)(1) are assigned to the ?2, ?3 and ?4 vibrations of AsO4(3)(-) unit, respectively. The Raman bands at 814, 779 and 403cm(-)(1) correspond to the ?1, ?3 and ?4 vibrations of AsO4(3)(-) unit respectively. The sharp bands at 3265cm(-)(1) for IR and 3270cm(-)(1) both reveals that the structural hydroxyl units exist in the austenite structure. The IR and Raman spectra both show that some SO4 units isomorphically replace AsO4 in austinite. X-ray single crystal diffraction provides the arrangement of each atom in the mineral structure, and also confirms that the conclusions made from the vibrational spectra. Micro-powder diffraction was used to confirm our mineral identification due to the small quantity of the austenite crystals.",
Arsenic,2298739,"Analysis of 3 algorithms for syphilis serodiagnosis and implications for clinical management Abstract: Background.?Algorithms for the diagnosis of syphilis continue to be a source of great controversy, and numerous test interpretations have perplexed many clinicians. Methods.?We conducted a cross-sectional study of 24 124 subjects to analyze 3 syphilis testing algorithms: traditional algorithm, reverse algorithm, and the European Centre for Disease Prevention and Control (ECDC) algorithm. Every serum sample was simultaneously evaluated using the rapid plasma reagin, Treponema pallidum particle agglutination, and chemiluminescence immunoassay tests. With the results of clinical diagnoses of syphilis as a gold standard, we evaluated the diagnostic accuracy of the 3 syphilis testing algorithms. The ? coefficient was used to compare the concordance between the reverse algorithm and the ECDC algorithm. Results.?Overall, 2749 patients in our cohort were diagnosed with syphilis. The traditional algorithm had the highest negative likelihood ratio (0.24), a missed diagnosis rate of 24.2%, and only 75.81% sensitivity. However, both the reverse and ECDC algorithms had higher diagnostic efficacy than the traditional algorithm. Their sensitivity, specificity, and accuracy were 99.38%-99.85%, 99.98%-100.00%, and 99.93%-99.96%, respectively. Moreover, the overall percentage of agreement and ? value between the reverse and the ECDC algorithms were 99.9% and 0.996, respectively. Conclusions.?Our research supported use of the ECDC algorithm, in which syphilis screening begins with a treponemal immunoassay that is followed by a second, different treponemal assay as a confirmatory test in high-prevalence populations. In addition, our results indicated that nontreponemal assay is unnecessary for syphilis diagnosis but can be recommended for determining serological activity and the effect of syphilis treatment.",
Arsenic,736200,"Maternal arsenic exposure associated with low birth weight in Bangladesh Abstract: Objective: To characterize the effects of maternal arsenic exposure on birth weight. Methods: Hair, toenail, and drinking water samples were collected from pregnant women (n = 52) at multiple time points during pregnancy and from their newborns after birth. Total arsenic was measured using inductively coupled plasma-mass spectrometry. The association between arsenic and birth weight was investigated using linear and logistic regression models. Results: Maternal hair arsenic measured early in pregnancy was associated with decreased birth weight (beta = -193.5 +/- 90.0 g, P = 0.04). Maternal hair and drinking water arsenic levels measured at first prenatal visit were significantly correlated with newborn hair arsenic level (rho = 0.32, P = 0.04 and rho = 0.31, P = 0.04). Conclusions: Results suggest that maternal arsenic exposure early in pregnancy negatively affects newborn birth weight and that maternal hair provides the best integrated measure of arsenic exposure.",
Arsenic,8676,"The effect of methyltransferase inhibition on the metabolism of [74As] arsenite in mice and rabbits Abstract: The effect of periodate-oxidized adenosine (PAD), an inhibitor of certain methyltransferases, on the biotransformation and tissue retention of [74As]arsenite in mice and rabbits was studied. Injection of PAD (100 ?mol/kg body wt.), 15 min prior to the injection of [74As]arsenite (0.4 mg As/kg body wt.), resulted in a 25–70% decrease in the production of [74As]dimethylarsinic acid ([74As]DMA). This implies that S-adenosylmethionine is the methyl-donor in the methylation of inorganic arsenic in vivo. Due to interaction of the unmethylated arsenite with tissue constituents the PAD-treated animals had significantly higher (2–6 times) tissue concentrations of 74As than did the controls. This effect was first observed in the liver, indicating that this organ is the main site of the methylation of arsenic. The increase in the tissue retention due to the PAD-treatment remained also after cessation of the inhibition of methylation. The results can be seen as confirmation that alkylation of inorganic arsenic acts as a detoxification mechanism in mammals.",
Arsenic,1015859,"Arsenite promotes apoptosis and dysfunction in microvascular endothelial cells via an alteration of intracellular calcium homeostasis Abstract: Vascular endothelium has been considered as a target for arsenic-induced cardiovascular toxicity. The present study demonstrated that arsenite caused slow and sustained elevation of intracellular free calcium levels ([Ca(2+)](i)) in HMEC-1, a human microvessel-derived endothelial cell line, in a concentration-dependent manner. Pretreatment with U-73122 (a specific PLC inhibitor) or 2-APB (a specific IP(3) receptor antagonist) attenuated this effect, suggesting that PLC/IP(3) signaling cascade is involved in arsenite-induced elevation of [Ca(2+)](i). Cytotoxic concentrations of arsenite (5 and 10?M) significantly enhanced endothelial nitric oxide synthase (eNOS) phosphorylation, nitric oxide (NO) production and apoptosis after 24-h exposure. Additionally, 2-APB attenuated eNOS phosphorylation and apoptosis induced by arsenite, indicating that Ca(2+)-mediated eNOS activation participates in arsenite-induced endothelial cell apoptosis. Moreover, we also found that non-apoptotic concentrations of arsenite (0.5 and 1?M) dramatically mitigated thrombin-induced rapid transient rise of [Ca(2+)](i), eNOS phosphorylation and NO production, suggesting functional disruption of endothelial by arsenite, and these effects occurred without an alteration of PLC-?(1) and thrombin receptor levels. Altogether, the results reveal that arsenite induces apoptotic cell death and endothelial dysfunction as indicated by the reduction of thrombin responses, particularly related to an alteration of intracellular Ca(2+) homeostasis.",
Arsenic,1327046,"Noncirrhotic portal fibrosis/idiopathic portal hypertension: APASL recommendations for diagnosis and treatment Abstract: The Asian Pacific Association for the Study of the Liver (APASL) Working Party on Portal Hypertension has developed consensus guidelines on the disease profile, diagnosis, and management of noncirrhotic portal fibrosis and idiopathic portal hypertension. The consensus statements, prepared and deliberated at length by the experts in this field, were presented at the annual meeting of the APASL at Kyoto in March 2007. This article includes the statements approved by the APASL along with brief backgrounds of various aspects of the disease.",
Arsenic,1579356,"Oxidative removal of arsenite by Fe(II)- and polyoxometalate (POM)-amended zero-valent aluminum (ZVAl) under oxic conditions Abstract: Abiotic transformation of As(III) to As(V) is possible which would decrease As toxicity. This study investigated the potential applications of zero-valent Al (ZVAl) or Al wastes, such as Al beverage cans, for converting As(III) to As(V) in an acidic solution under aerobic conditions. Results showed that As(III) could not be oxidized by ZVAl within 150 min reaction at pH 1 because of the presence of an oxide layer on ZVAl. However, 85 ?M As(III) could be completely oxidized with the addition of Fe(II) or POM due to the generation of a Fenton reaction or the enhancement of H2O2 production, respectively, on the ZVAl surfaces. Because Fe(II) or polyoxometalate (POM) exhibited more stable at low pH and scavenged rapidly the H2O2 produced on the aerated ZVAl surfaces, OH radical productions were more efficient and As(III) was rapidly oxidized in the ZVAl/O2 system with theses two catalysts. The catalytic oxidation kinetics of As(III) in the presence of Fe(II) or POM were best described by zero-order reaction, and the rate constants increased with a decrease of pH from 2 to 1. Following the oxidative conversion of As(III) to As(V) in the ZVAl/Fe/O2 system, As(V) was removed by the newly formed hydrous Al/Fe precipitates by increasing the solution pH to 6. Nonetheless, the As(V) removal was incomplete in the ZVAl/POM/O2 system because the hydrolyzed products of POM, e.g., PO4(3-), inhibited As(V) removal due to the competitive adsorption of the oxyanion on Al precipitates. Discarded Al-based beverage cans exhibit a higher efficiency for As(III) oxidation and final As removal compared with that of ZVAl, and thus, the potential application of Al beverage cans to scavenge As in solutions is feasible.",
Arsenic,627590,"Mechanisms of arsenic-induced cell transformation Abstract: Arsenic is a well-established carcinogen in humans, but there is little evidence for its carcinogenicity in animals and it is inactive as an initiator or tumor promoter in two-stage models of carcinogenicity in mice. Studies with cells in culture have provided some possible mechanisms by which arsenic and arsenical compounds may exert a carcinogenic activity. Sodium arsenite and sodium arsenate were observed to induce morphological transformation of Syrian hamster embryo cells in a dose-dependent manner. The trivalent sodium arsenite was greater than tenfold more potent than the pentavalent sodium arsenate. The compounds also exhibited toxicity; however, transformation was observed at nontoxic as well as toxic doses. At low doses, enhanced colony forming efficiency of the cells was observed. To understand the mechanism of arsenic-induced transformation, the genetic effects of the two arsenicals were examined over the same doses that induced transformation. No arsenic-induced gene mutations were detected at two genetic loci. However, cell transformation and cytogenetic effects, including endoreduplication, chromosome aberrations, and sister chromatid exchanges, were induced by the arsenicals with similar dose responses. These results support a possible role for chromosomal changes in arsenic-induced transformation. The two arsenic salts also induced another form of mutation-gene amplification. Both sodium arsenite and sodium arsenate induced a high frequency of methotrexate-resistant 3T6 cells, which were shown to have amplified copies of the dihydrofolate reductase gene.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,1015831,"Cadmium and lung cancer mortality accounting for simultaneous arsenic exposure Abstract: ObjectivesPrior investigations identified an association between airborne cadmium and lung cancer but questions remain regarding confounding by arsenic, a well-established lung carcinogen.MethodsA cadmium smelter population exhibiting excess lung cancer was re-analysed using a retrospective exposure assessment for arsenic (As), updated mortality (1940-2002), a revised cadmium (Cd) exposure matrix and improved work history information.ResultsCumulative exposure metrics for both cadmium and arsenic were strongly associated making estimation of their independent effects difficult. Standardised mortality ratios (SMRs) were modelled with Poisson regression with the contribution of arsenic to lung cancer risk constrained by exposure-response estimates previously reported. The results demonstrate (1) a statistically significant effect of Cd independent of As (SMR=3.2 for 10 mg-year/m(3) Cd, p=0.012), (2) a substantial healthy worker effect for lung cancer (for unexposed workers, SMR=0.69) and (3) a large deficit in lung cancer mortality among Hispanic workers (SMR=0.27, p=0.009), known to have low lung cancer rates. A supralinear dose-rate effect was observed (contribution to risk with increasing exposure intensity has declining positive slope). Lung cancer mortality was somewhat better predicted using a cadmium burden metric with a half-life of about 20-25 years.ConclusionsThese findings support an independent effect for cadmium in risk of lung cancer mortality. 1/1000 excess lifetime risk of lung cancer death is predicted from an airborne exposure of about 2.4 ?g/m(3) Cd.",
Arsenic,2347635,"A comprehensive evaluation of inorganic arsenic in food and considerations for dietary intake analyses Abstract: Arsenic (As) can exist in the environment in several different forms, each having unique chemical characteristics that influence its toxicity and potential for human and ecological exposure. Within the last decade or so, the focus on speciated As (both the inorganic and organic forms) and its potential toxicity has led to an increased availability of data on speciated As in different food types. To gain an understanding of these developments and the current science, we evaluated the state of knowledge regarding As speciation in food and calculated the average levels of several species of As measured in food. Because inorganic arsenic (inAs) is considered the most toxicologically important form of As, we focused our analysis on papers presenting information on total inAs and speciated inAs (inAs(3+) or inAs(5+)). We also evaluated speciated As forms (e.g., monomethylarsonic and dimethylarsinic acid) when presented with inAs information. Publications were drawn from the peer-reviewed literature and reports by authoritative health agencies. While a great deal of speciation data were identified, including over 6500 unique inAs data points, unclear study methodology and inconsistencies between studies introduced uncertainty into the analysis of these data. Despite these limitations, our analysis demonstrates that inAs in foods can vary widely by type and even by sample, with mean inAs concentrations ranging from undetectable (in milk) to 11,000?g/kg (in seaweed/algae). We found a high percentage of non-measurable As in many food types, suggesting that the limits of detection of speciated As must be considered to accurately estimate dietary As exposure. The applicability of our analysis is limited by the inconsistencies and uncertainties in the available data; calculations of inAs dietary intake should be tailored to the study population of interest and should consider study quality.",
Arsenic,2149194,Determination and identification of hydrophilic and hydrophobic arsenic species in methanol extract of fresh cod liver by RP-HPLC with simultaneous ICP-MS and ESI-Q-TOF-MS detection Abstract: The present study was focused on the determination and identification of arsenic species in methanolic extracts of cod liver. Arsenic species were fractionated and the fractions analysed by RP-HPLC-ICP-MS coupled with ESI-Q-TOF-MS. The total concentration of arsenic in the fresh cod liver was analysed by ICP-MS to be 1.53±0.02 mg As kg(-1)w.w. and the extraction recovery was ca. 100% and the column recovery &gt;93%. Besides polar inorganic and methylated arsenic species (&gt;70%) more hydrophobic arsenic-containing fatty acids and hydrocarbons occurred. Based on the mass spectrometric data proposals for molecular structures were elaborated for 20 of the organic As species included 10 arsenic-containing fatty acids (AsFA) and an arsenic-containing hydrocarbon (AsHC) mentioned for the first time in fresh cod liver. Arsenobetaine was found as main water-soluble arsenic compound in cod liver followed by higher molecular mass arsenic-containing fatty acids and hydrocarbons.,
Arsenic,894699,"Mushroom lectin protects arsenic induced apoptosis in hepatocytes of rodents Abstract: Acute and chronic arsenic exposure result in toxicity both in human and animal beings and cause many hepatic and renal manifestations. The present study stated that mushroom lectin prevents arsenic-induced apoptosis. Apoptosis was measured by morphological alterations, cell proliferation index (CPI), phagocytic activity (nitro blue tetrazolium index; NBT), nitric oxide (NO) production, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, DNA fragmentation and caspase-3 activity. Arsenic exposure at 5 ?M in the form of sodium arsenite resulted in significant elevation of deformed cells, NO production, TUNEL stained nuclei of hepatocytes, DNA fragmentation and caspase-3 activity. But the CPI and NBT index were significantly declined in arsenic-treated hepatocytes. The beneficial effect of mushroom lectin at 10 ?g/mL, 20 ?g/mL and 50 ?g/mL) showed increased CPI and phagocytic activity. Mushroom lectin at those concentrations reduced deformed cells, NO production, DNA fragmentation and caspase-3 activity of hepatocytes. But significant better protection was observed in 50 ?g/mL mushroom lectin-treated hepatocytes. This finding may be of therapeutic benefit in people suffering from chronic arsenic exposure.",
Arsenic,2064277,"Arsenic exposure affects embryo development of sea urchin, Paracentrotus lividus (Lamarck, 1816) Abstract: Toxicity tests were performed with embryos of Paracentrotus lividus to investigate the toxicological effect of two arsenic species: arsenate (As(V)), expected to be more toxic, and dimethyl-arsinate (DMA) expected to be less toxic. Exposures to toxicants were performed at different developmental stages in order to identify the most sensitive phase of embryological development. Statistical analysis revealed a high significance of each factor (Molecule, Concentration and Time of exposure) and their interaction for the dependent variable &quot;Percentage of normal-shaped plutei&quot;. In particular, the 8 cell stage was the most sensitive to arsenic; at a concentration of 50 ?g L(-1) DMA proved to be more toxic than As(V), resulting in nearly 50 % of normal-shaped plutei against the 74 % recorded for As(V). Starting the administration of arsenic at the morula stage, arsenate proved to be significantly more toxic when compared to DMA.",
Arsenic,1579329,"Association of arsenic, cadmium and manganese exposure with neurodevelopment and behavioural disorders in children: A systematic review and meta-analysis Abstract: The aim of this study was to analyse the scientific evidence published to date on the potential effects on neurodevelopment and behavioural disorders in children exposed to arsenic, cadmium and manganese and to quantify the magnitude of the effect on neurodevelopment by pooling the results of the different studies. We conducted a systematic review of original articles from January 2000 until March 2012, that evaluate the effects on neurodevelopment and behavioural disorders due to pre or post natal exposure to arsenic, cadmium and manganese in children up to 16years of age. We also conducted a meta-analysis assessing the effects of exposure to arsenic and manganese on neurodevelopment. Forty-one articles that evaluated the effects of metallic elements on neurodevelopment and behavioural disorders met the inclusion criteria: 18 examined arsenic, 6 cadmium and 17 manganese. Most studies evaluating exposure to arsenic (13 of 18) and manganese (14 of 17) reported a significant negative effect on neurodevelopment and behavioural disorders. Only two studies that evaluated exposure to cadmium found an association with neurodevelopmental or behavioural disorders. The results of our meta-analysis suggest that a 50% increase of arsenic levels in urine would be associated with a 0.4 decrease in the intelligence quotient (IQ) of children aged 5-15years. Moreover a 50% increase of manganese levels in hair would be associated with a decrease of 0.7 points in the IQ of children aged 6-13years. There is evidence that relates arsenic and manganese exposure with neurodevelopmental problems in children, but there is little information on cadmium exposure. Few studies have evaluated behavioural disorders due to exposure to these compounds, and manganese is the only one for which there is more evidence of the existence of association with attention deficit disorder with hyperactivity.",
Arsenic,1343343,"Regulation by heat shock protein 27 of osteocalcin synthesis in osteoblasts Abstract: We have previously reported that various stimuli, including sphingosine 1-phosphate, are able to induce heat shock protein (HSP) 27 in osteoblast-like MC3T3-E1 cells. However, the precise role of HSP27 in bone metabolism has not been satisfactory clarified. In this study, we investigated the effect of HSP27 on osteocalcin synthesis induced by bone morphogenetic protein (BMP)-4 or T? in these cells. In MC3T3-E1 cells, pretreatment with sphingosine 1-phosphate, sodium arsenite, or heat stress caused the attenuation of osteocalcin synthesis induced by BMP-4 or T? with concurrent HSP27 induction. To further investigate the effect of HSP27, we established stable HSP27-transfected cells. The osteocalcin synthesis was significantly reduced in the stable HSP27-transfected MC3T3-E1 cells and normal human osteoblasts compared with empty-vector transfected cells. On the other hand, anisomycin, a p38 MAPK activator, caused the phosphorylation of HSP27 in both sphingosine 1-phosphate-stimulated untransfected MC3T3-E1 cells and HSP27-transfected MC3T3-E1 cells. An immunofluorescence microscopy study showed that the phosphorylated HSP27 induced by anisomycin concentrated perinuclearly in these cells, in which it colocalized with the endoplasmic reticulum. We also established stable mutant-HSP27-transfected cells. Osteocalcin synthesis induced by either BMP-4 or T? was markedly suppressed in the nonphosphorylatable HSP27-overexpressing MC3T3-E1 cells compared with the phosphomimic HSP27-overexpressing cells. In contrast, the matrix mineralization was more obvious in nonphosphorylatable HSP27-overexpressing cells than that in phosphomimic HSP27-overexpressing cells. Taken together, these results strongly suggest that unphosphorylated HSP27 has an inhibitory effect on osteocalcin synthesis, but has a stimulatory effect on mineralization, in osteoblasts.",
Arsenic,566581,"Dual treatment with COX-2 inhibitor and sodium arsenite leads to induction of surface Fas Ligand expression and Fas-Ligand-mediated apoptosis in human melanoma cells Abstract: Most human melanomas express Fas receptor on the cell surface, and treatment with exogenous Fas Ligand (FasL) efficiently induces apoptosis of these cells. In contrast, endogenous surface expression of FasL is suppressed in Fas-positive melanomas. We report here the use of a combination of sodium arsenite, an inhibitor of NF-[kappa]B activation, and NS398, a cyclooxygenase-2 (COX-2) inhibitor, for restoration of the surface FasL expression. We observed a large increase of Fas-mediated apoptosis in Fas-positive melanomas. This was due to induction of FasL surface expression and increased susceptibility to Fas death signaling after arsenite and NS398 treatment. Furthermore, silencing COX-2 expression by specific RNAi also effectively increased surface FasL expression following arsenite treatment. Upregulation of the surface FasL levels was based on an increase in the efficiency of translocation to the cell surface and stabilization of FasL protein on the cell surface, rather than on acceleration of the FasL gene transcription. Data obtained demonstrate that the combination of arsenite with inhibitors of COX-2 may affect the target cancer cells via induction of FasL-mediated death signaling.",
Arsenic,1360614,Cirrhosis of the liver in chronic arsenical poisoning of vintners Abstract: ,
Arsenic,628234,"Arsenic speciation in bile and urine following oral and intravenous exposure to inorganic and organic arsenics in rats Abstract: Although inorganic arsenate (iAsV) and arsenite (iAsIII) are metabolized in liver and excreted into bile and urine, the metabolites in the bile after the oral intake of iAs remain unclear. Male Sprague-Dawley rats were orally (po) or intravenously (iv) exposed to iAs and methylated arsenics, and the arsenic speciation in the urine and bile was analyzed by high performance liquid chromatography-inductively coupled argon plasma mass spectrometry. Arsenic caused induction of multidrug resistance-associated protein 2 (MRP2), and changes of glutathione (GSH) levels in the liver and bile were also determined. The metabolic speciation studies revealed that arsenic was excreted into bile in the methylarsenic-diglutathione (MADG) and/or dimethylarsenic acid (DMAV) forms in iAsIII- or iAsV-po rats, but that MADG and arsenic-triglutathione (ATG) are the main forms excreted into bile both in iAsIII- and iAsV-iv rats. In MADG-po rats, the MADG was excreted into bile in the MADG and DMAV forms. Monomethylarsonic acid (MMAV)- and DMAV-iv rats did not excrete significant amounts of either MMAV or DMAV into bile and mostly excreted into urine in the unchanged chemical forms. Taken together, the DMAV detected in the bile is mostly supposed to be the dissociation of dimethylarsenic-glutathione (DMAG). Urinary arsenic speciation showed that arsenic metabolized to 43% methylated DMAV, 47% unmethylated iAsIII, and 10% iAsV in iAsIII-iv rats, whereas only 3% methylated DMAV, 87% unmethylated iAsV, and 10% iAsIII were detected in iAsV-iv rats. Arsenic was accumulated dose dependently, and arsenic concentration was significantly higher in the iAsIII-po rat liver than in the iAsV-po rat liver. GSH levels in the bile were decreased by relatively higher doses of iAsV-po, but significantly increased by iAsIII- or iAsV-iv. iAs-exposure increased the expression of MRP2 in the liver. Pretreatment with buthionine sulfoximine predominantly inhibited arsenic excretion into bile in iAs-iv rats. In conclusion, our data demonstrated that biliary and urinary arsenic excretion and speciation are affected by the route, dose, and chemical forms of arsenical administration, and GSH plays a key role in arsenic metabolism. We are also first to show that DMAV that probably originated from DMAG is excreted into the bile in iAs-po rats.",
Arsenic,1032418,"Ambient air arsenic levels along the Texas-Mexico border Abstract: The Texas-Mexico border region is one of the most rapidly developing areas in the state. Unprecedented economic and demographic growth is placing stress on a system already overburdened with air, water, waste, and public health problems. This paper reports the results of an initial survey of the past and present ambient air levels of arsenic along the Texas side of the border. Ambient air arsenic levels have increased over time, exhibit seasonal variations, and are higher in specific areas when compared to the rest of the state. Five of the 20 areas in Texas having the highest 24-hour levels of arsenic are found along the border. In areas where emissions have been significantly reduced at the source, arsenic levels remained high in the environment for over two years. This provides a potential continuum for human exposure. The results of this study emphasize the need for bi-national development and implementation of air quality control programs along the Texas-Mexico border.",
Arsenic,2337066,"Two tetra-CdII-substituted vanadogermanate frameworks Abstract: Two new tetra-CdII-substituted vanadogermanate frameworks {(CdX)4Ge8VIV10O46(H2O)[VIII(H2O)2]4(GeO2)4}?8H2O (X = ethylenediamine (en, 1) and 1,2-diaminopropane (dap, 2)) were hydrothermally prepared and characterized by IR spectra, elemental analysis, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Xray single-crystal diffraction. Both are isomorphic, and their 3-D frameworks are made up of tetra-CdII-substituted {(CdX)4Ge8VIV10O46(H2O)}12– fundamental building units interconnected through planar tetra-VIII [VIII4O2(H2O)8]8– clusters and tetrahedral GeO4 bridges. In the unique{(CdX)4Ge8VIV10O46(H2O)}12– cage, four [Ge2O7] dimers and four CdO4N2 trigonal prisms are alternately concatenated by ?3-O bridges to create a round {Ge8Cd4O28(X)4}16- fragment, five VO5 groups are linked by sharing edges to generate a pentanuclear [V5O17] subunit, and then the {Ge8Cd4O28(X)4}16- fragment is sandwiched by two V5O17 subunits via sharing O-atoms producing a D4h-symmetric {(CdX)4(Ge8VIV10O46)(H2O)}12- cage with a free water molecule located at the center. As we know, both display unprecedented 3-D organic inorganic hybrid frameworks built up from the largest number of transition-metal-substituted vanadogermanate {(CdX)4Ge8VIV10O46)}12- cluster shells linked by both GeO4 tetrahedra and rare [VIII4O2(H2O)8]8- clusters. Magnetic measurements reveal the antiferromagnetic couplings within the magnetic vanadium centers.",
Arsenic,627621,"Case-control study of bladder cancer and exposure to arsenic in Argentina Abstract: Studies have found increased bladder cancer risks associated with high levels of arsenic in drinking water, but little information exists about risks at lower concentrations. Ecologic studies in Argentina have found increased bladder cancer mortality in Córdoba Province, where some wells are contaminated with moderate arsenic concentrations. This population-based bladder cancer case-control study in two Córdoba counties recruited 114 case-control pairs, matched on age, sex, and county, during 1996-2000. Water samples, particularly from wells, were obtained from subjects' current residences and residences in the last 40 years. Statistical analyses showed no evidence of associations with exposure estimates based on arsenic concentrations in drinking water. However, when well-water consumption per se was used as the exposure measure, time-window analyses suggested that use of well water more than 50 years before interview was associated with increased bladder cancer risk. This association was limited to ever smokers (odds ratio = 2.5, 95% confidence interval: 1.1, 5.5 for 51-70 years before interview), and the possibility that this association is due to chance cannot be excluded. This study suggests lower bladder cancer risks for arsenic than predicted from other studies but adds to evidence that the latency for arsenic-induced bladder cancers may be longer than previously thought.",
Arsenic,1327089,"Cyclin B1 proteolysis via p38 MAPK signaling participates in G2 checkpoint elicited by arsenite Abstract: Timely induction of cyclin B1 controls mitotic entry, whereas its proteolysis is essential for mitotic exit. By contrast, cyclin B1 transcription is repressed during G(2) arrest induced by DNA damage. The p38 mitogen-activated protein kinase is involved in the G(2) checkpoint; yet, its impact on cyclin B1 protein levels remains unclear. Here we show that untimely proteolysis of cyclin B1 following p38 activation contributes to G(2) checkpoint. Exposing early G(2) cells to arsenite impeded cyclin B1 protein accumulation, Cdk1 activation, and G(2)-to-M progression. Conversely, cyclin B1 was non-degradable in late G(2) and mitotic cells after arsenite. Cyclin B1 proteolysis was enhanced by arsenite in early G(2) and asynchronous cells. This rapid destruction of cyclin B1 was mediated via the ubiquitin-proteasome pathway probably in a Cdc20 and Cdh1 independent mechanism. Under arsenite, inhibition of p38 activation or depletion of p38alpha suppressed cyclin B1 ubiquitination and proteolysis, while forced expression of MKK6-p38 accelerated these events. Inactivation of p38 in arsenite-treated early G(2) cells allowed G(2)-to-M progression, blocked apoptosis, increased cell viability, and decreased micronucleus formation. Thus, p38 signaling pathway triggering cyclin B1 proteolysis after arsenite may play an important role in connecting G(2) arrest with apoptosis or genome instability.",
Arsenic,501788,"Efficacy of spirulina extract plus zinc in patients of chronic arsenic poisoning: A randomized placebo-controlled study Abstract: Background . Millions of people in Bangladesh, India, Taiwan, and Chile are consuming high concentration of arsenic through drinking water, and thousands of them have already developed chronic arsenic poisoning. There is no specific treatment. Some authors suggest the use of vitamins and minerals for more than 6 months. The present placebo-controlled double-blind study was conducted to evaluate effectiveness of spirulina extract plus zinc in the treatment of chronic arsenic poisoning. Methods . Forty-one patients of chronic arsenic poisoning were randomly treated orally by either placebo (17 patients) or spirulina extract (250 mg) plus zinc (2 mg) (24 patients) twice daily for 16 weeks. Each patient was supplied with arsenic-safe drinking water by installing a locally made water filter at household level. Effectiveness of spirulina extract plus zinc was evaluated by comparing changes in skin manifestations (clinical scores), arsenic contents in urine and hair, between the placebo- and spirulina extract plus zinc-treated groups. Results . The concentrations of total arsenic in water (without filtration) of placebo- and spirulina extract plus zinc-treated groups were 150.1 +/- 18.3 and 161.7 +/- 23.9 mu g/l, respectively. Intake of these high concentrations of arsenic lead to increased excretion of arsenic in urine (72.1 +/- 14.5 mu g/l in placebo-treated group and 78.4 +/- 19.1 mu g/l in spirulina plus zinc-treated group). After 2 weeks of using filtered water, there were significant reduction of both arsenic intake through water and urinary arsenic excretion (8.3 +/- 3.6 mu g/l and 18.4 +/- 7.3 mu g/l in placebo group; 9.7 +/- 5.4 mu g/l and 21.6 +/- 5.8 mu g/l) in spirulina extract plus zinc-treated group. There was a sharp increase in urinary excretion of arsenic (138 +/- 43.6 mu g/l) at 4 weeks following spirulina plus zinc administration and the effect was continued for another 2 weeks. Spirulina extract plus zinc removed 47.1% arsenic from scalp hair. Spirulina extract had no major adverse effect that required physician's attention. The clinical scores (median) for melanosis before and after treatment with placebo was not statistically significant (p>0.05), whereas in spirulina extract plus zinc-treated group it was statistically significant (p<0.01). In cases of keratosis, the median clinical scores before and after treatment was not statistically significant (p>0.05) in placebo-treated group. In spirulina extract plus zinc-treated group, the clinical scores for keratosis before and after treatment was statistically significant (p<0.05). Conclusions: Results show that spirulina extract (250 mg) plus zinc (2 mg) twice daily for 16 weeks may be useful for the treatment of chronic arsenic poisoning with melanosis and keratosis.",
Arsenic,1508692,"Arsenite removal from aqueous solutions by ?-Fe(2)O(3)-TiO(2) magnetic nanoparticles through simultaneous photocatalytic oxidation and adsorption Abstract: A novel Fe-Ti binary oxide magnetic nanoparticles which combined the photocatalytic oxidation property of TiO(2) and the high adsorption capacity and magnetic property of ?-Fe(2)O(3) have been synthesized using a coprecipitation and simultaneous oxidation method. The as-prepared samples were characterized by powder XRD, TEM, TG-DTA, VSM and BET methods. Photocatalytic oxidation of arsenite, the effect of solution pH values and initial As(III) concentration on arsenite removal were investigated in laboratory experiments. Batch experimental results showed that under UV light, As(III) can be efficiently oxidized to As(V) by dissolved O(2) in ?-Fe(2)O(3)-TiO(2) nanoparticle suspensions at various pH values. At the same time, As(V) was effectively removed by adsorption onto the surface of nanoparticles. The maximum removal capability of the nano-material for arsenite was 33.03mg/g at pH 7.0. Among all the common coexisting ions investigated, phosphate was the greatest competitor with arsenic for adsorptive sites on the nano-material. Regeneration studies verified that the ?-Fe(2)O(3)-TiO(2) nanoparticles, which underwent five successive adsorption-desorption processes, still retained comparable catalysis and adsorption performance, indicating the excellent stability of the nanoparticles. The excellent photocatalytic oxidation performance and high uptake capability of the magnetic nano-material make it potentially attractive material for the removal of As(III) from water.",
Arsenic,1597343,"Stream water chemistry in the arsenic-contaminated Baccu Locci mine watershed (Sardinia, Italy) after remediation Abstract: The abandoned Pb-As Baccu Locci mine represents the first and only case of mine site remediation in Sardinia, Italy. Arsenic is the most relevant environmental concern in the Baccu Locci stream watershed, with concentrations in surface waters up to and sometimes over 1 mg/L. The main remediation action consisted in creation of a &quot;storage site&quot;, for the collection of contaminated materials from different waste-rock dumps and most of tailings piles occurring along the Baccu Locci stream. This paper reports preliminary results on the level of contamination in the Baccu Locci stream after the completion of remediation measures. Post-remediation stream water chemistry has not substantially changed compared to the pre-remediation situation. In particular, dissolved As maintains an increasing trend along the Baccu Locci stream, with a concentration of about 400 ?g/L measured at a distance of 7 km from the storage site. Future monitoring will provide fundamental information on the effectiveness of remediation actions conducted and their applicability to other mine sites in Sardinia. At the stage of mine site characterisation of future remediation plans, it is recommended to pay more attention to the understanding of mineralogical and geochemical processes responsible for pollution. Moreover, mixing of materials with different composition and reactivity in a storage site should require careful consideration and long-term leaching tests.",
Arsenic,1346100,Physics of rare events: insights on Napoleon death Abstract: ,
Arsenic,1025215,"Arsenic alters vascular smooth muscle cell focal adhesion complexes leading to activation of FAK-src mediated pathways Abstract: Chronic exposure to arsenic has been linked to tumorigenesis, cardiovascular disease, hypertension, atherosclerosis, and peripheral vascular disease; however, the molecular mechanisms underlying its pathological effects remain elusive. In this study, we investigated arsenic-induced alteration of focal adhesion protein complexes in normal, primary vascular smooth muscle cells. We demonstrate that exposure to environmentally relevant concentrations of arsenic (50 ppb As(3+)) can alter focal adhesion protein co-association leading to activation of downstream pathways. Co-associated proteins were identified and quantitated via co-immunoprecipitation, SDS-PAGE, and Western blot analysis followed by scanning densitometry. Activation of MAPK pathways in total cell lysates was evaluated using phosphor-specific antibodies. In our model, arsenic treatment caused a sustained increase in FAK-src association and activation, and induced the formation of unique signaling complexes (beginning after 3-hour As(3+) exposure and continuing throughout the 12-hour time course studied). The effects of these alterations were manifested as chronic stimulation of downstream PAK, ERK and JNK pathways. Past studies have demonstrated that these pathways are involved in cellular survival, growth, proliferation, and migration in VSMCs.",
Arsenic,627793,"MRP2 and acquired tolerance to inorganic arsenic in the kidney of killifish (Fundulus heteroclitus) Abstract: We used proximal tubules isolated from the killifish, Fundulus heteroclitus, to examine the effect of environmentally relevant, sublethal levels of arsenic on the function and expression of MRP2, an ABC transporter that transports xenobiotics into urine, including arsenic-glutathione conjugates. Exposure of fish to arsenic as sodium arsenite (4-14 days) increased both MRP2 expression in the apical membrane of proximal tubules and MRP2-mediated transport activity. The level of MRP2 mRNA was not affected, suggesting a posttranslational mechanism of action. Acute exposure of proximal tubules isolated from control fish to 75-375 ppb arsenic decreased mitochondrial function (inner membrane electrical potential). However, in tubules from fish that were preexposed to arsenic (4-14 days), no such effect on mitochondrial function was observed. Thus, chronic in vivo exposure to arsenic induces mechanisms that protect proximal tubules during subsequent arsenic exposure. Upregulation of MRP2 expression and activity is one likely contributing factor.",
Arsenic,628410,"Human monomethylarsonic acid (MMA(V)) reductase is a member of the glutathione-S-transferase superfamily Abstract: The drinking of water containing large amounts of inorganic arsenic is a worldwide major public health problem because of arsenic carcinogenicity. Yet an understanding of the specific mechanism(s) of inorganic arsenic toxicity has been elusive. We have now partially purified the rate-limiting enzyme of inorganic arsenic metabolism, human liver MMA(V) reductase, using ion exchange, molecular exclusion, and hydroxyapatite chromatography. When SDS-beta-mercaptoethanol-PAGE was performed on the most purified fraction, seven protein bands were obtained. Each band was excised from the gel, sequenced by LC-MS/MS and identified according to the SWISS-PROT and TrEMBL Protein Sequence databases. Human liver MMA(V) reductase is 100% identical, over 92% of sequence that we analyzed, with the recently discovered human glutathione-S-transferase Omega class hGSTO 1-1. Recombinant human GSTO1-1 had MMA(V) reductase activity with K(m) and V(max) values comparable to those of human liver MMA(V) reductase. The partially purified human liver MMA(V) reductase had glutathione S-transferase (GST) activity. MMA(V) reductase activity was competitively inhibited by the GST substrate, 1-chloro 2,4-dinitrobenzene and also by the GST inhibitor, deoxycholate. Western blot analysis of the most purified human liver MMA(V) reductase showed one band when probed with hGSTO1-1 antiserum. We propose that MMA(V) reductase and hGSTO 1-1 are identical proteins.",
Arsenic,628094,"Incidence of transitional cell carcinoma and arsenic in drinking water: A follow-up study of 8,102 residents in an arseniasis-endemic area in northeastern Taiwan Abstract: A significant association between ingested arsenic and bladder cancer has been reported in an arseniasis-endemic area in southwestern Taiwan, where many households share only a few wells in their villages. In another arseniasis-endemic area in northeastern Taiwan, each household has its own well for obtaining drinking water. In 1991-1994, the authors examined risk of transitional cell carcinoma (TCC) in relation to ingested arsenic in a cohort of 8,102 residents in northeastern Taiwan. Estimation of each study subject's individual exposure to inorganic arsenic was based on the arsenic concentration in his or her own well water, which was determined by hydride generation combined with atomic absorption spectrometry. Information on duration of consumption of the well water was obtained through standardized questionnaire interviews. The occurrence of urinary tract cancers was ascertained by follow-up interview and by data linkage with community hospital records, the national death certification profile, and the cancer registry profile. Cox proportional hazards regression analysis was used to estimate multivariate-adjusted relative risks and 95% confidence intervals. There was a significantly increased incidence of urinary cancers for the study cohort compared with the general population in Taiwan (standardized incidence ratio = 2.05; 95% confidence interval (CI): 1.22, 3.24). A significant dose-response relation between risk of cancers of the urinary organs, especially TCC, and indices of arsenic exposure was observed after adjustment for age, sex, and cigarette smoking. The multivariate-adjusted relative risks of developing TCC were 1.9, 8.2, and 15.3 for arsenic concentrations of 10.1-50.0, 50.1-100, and >100 microg/liter, respectively, compared with the referent level of < or =10.0 microg/liter.",
Arsenic,1519089,"Direct investigation of silver photodissolution dynamics and reversibility in arsenic trisulphide thin films by atomic force microscopy Abstract: The dynamics and reversibility of Ag nanoparticle photodissolution into AsS chalcogenide thin films have uniquely been directly measured by continuous AFM imaging during patterned optical illumination. The surface morphology, roughness and particle size distribution have thus been spatially and statistically monitored as a function of time, both during and following optical exposure. Photodissolution was observed to proceed via two mechanisms. In one case, nanoparticles abruptly and nearly completely disappeared along a sharp dissolution front traveling laterally at ?0.19 ?m s. Following illumination, similarly sized nanoparticles uniformly reformed on the surface. A more inhomogeneous photodissolution process was separately recorded, clearing irregular ?1-2 ?m patches that grew with time until most of the surface was free of nanoparticles. Post-illumination, surface nanoparticle development and coverage were similarly inhomogeneous, with larger but 50% fewer particles in the final distribution. In every experiment, an initial roughening was detected before the nanoparticle surface coverage visually diminished, indicating the onset of photodissolution at widely distributed energetically and kinetically favored sites which temporarily enhances nanoscale roughness. Such direct studies of surface dynamics are crucial to understanding and ultimately optimizing chalcogenide film applications such as photomasks, optoelectronics media and bio-chemical sensors.",
Arsenic,1936187,"Procedia Earth and Plantetary Science Hydrogeochemical trends of the Valenciana tailings, Mexico Abstract: ",
Arsenic,1677522,"Fate of arsenic during microbial reduction of biogenic vs. abiogenic As-Fe(III)-mineral co-precipitates Abstract: Fe(III) (oxyhydr)oxide minerals exhibit a high sorption affinity for arsenic (As) and the reductive dissolution of As-bearing Fe(III) (oxyhydr)oxides is considered to be the primary mechanism for As release into groundwater. To date, research has focused on the reactivity of abiogenic Fe(III) (oxyhydr)oxides, yet in nature biogenic Fe(III) (oxyhydr)oxides, precipitated by Fe(II)-oxidizing bacteria are also present. These biominerals contain cell-derived organic matter (CDOM), leading to different properties than their abiogenic counterparts. Here, we follow Fe mineralogy and As mobility during the reduction of As-loaded biogenic and abiogenic Fe(III) minerals by Shewanella oneidensis MR-1. We found that microbial reduction of As(III)-bearing biogenic Fe(III) (oxyhydr)oxides released more As than reduction of abiogenic Fe(III) (oxyhydr)oxides. In contrast, As was immobilized more effectively during reduction of As(V)-loaded biogenic than abiogenic Fe(III) (oxyhydr)oxides during secondary Fe mineral formation. During sterile incubation of minerals and after microbial Fe(III) reduction stopped, As(V) was mobilized from biogenic Fe(III) (oxyhydr)oxides probably by sorption competition with phosphate and CDOM. Our data show that the presence of CDOM significantly influences As mobility during reduction of Fe(III) minerals and we suggest that it is essential to consider both biogenic and abiogenic Fe(III) (oxyhydr)oxides to further understand the environmental fate of As.",
Arsenic,2337251,"A prospective study of arm circumference and risk of death in Bangladesh Abstract: BACKGROUND: Epidemiological studies have observed protective effects of mid-upper arm circumference (MUAC) against all-cause mortality mostly in Western populations. However, evidence on cause-specific mortality is limited. METHODS: The sample included 19 575 adults from a population-based cohort study in rural Bangladesh, who were followed up for an average of 7.9 years for mortality. Cox proportional hazards regression was used to evaluate the effect of MUAC, as well as the joint effect of body mass index (BMI) and MUAC, on the risk of death from any cause, cancer and cardiovascular disease (CVD). RESULTS: During 154 664 person-years of follow-up, 744 deaths including 312 deaths due to CVD and 125 deaths due to cancer were observed. There was a linear inverse relationship of MUAC with total and CVD mortality. Each 1-cm increase in MUAC was associated a reduced risk of death from any cause [hazard ratio (HR) = 0.85; 95% confidence interval (C), 0.81-0.89) and CVD (HR = 0.87; 95% CI, 0.80-0.94), after controlling for potential confounders. No apparent relationship between MUAC and the risk of death from cancer was observed. Among individuals with a low BMI (<18.5 kg/m2), a MUAC less than 24 cm was associated with increased risk for all-cause (HR = 1.81; 95% CI, 1.52-2.17) and CVD mortality (HR = 1.45; 95% CI, 1.11-1.91). CONCLUSIONS: MUAC may play a critical role on all-cause and CVD mortality in lean Asians.",
Arsenic,2343539,"Environmental genotoxicity and cytotoxicity in flounder (Platichthys flesus), herring (Clupea harengus) and Atlantic cod (Gadus morhua) from chemical munitions dumping zones in the southern Baltic Sea Abstract: The data on environmental genotoxicity and cytotoxicity levels as well as on genotoxicity risk in flounder (Platichthys flesus), herring (Clupea harengus) and cod (Gadus morhua) collected in 2010-2012 at 42 stations located in chemical munitions dumping areas of the southern Baltic Sea are presented. The frequency of micronuclei, nuclear buds and nucleoplasmic bridges in erythrocytes was used as genotoxicity endpoint and the induction of fragmented-apoptotic, bi-nucleated and 8-shaped erythrocytes as cytotoxicity endpoint. The most significantly increased geno-cytotoxicity levels were determined in fish collected near known chemical munitions dumpsites. Extremely high genotoxicity risk for flounder were identified at 21 out of 24 stations, for herring at 29 out of 31 and for cod at 5 out of 10 stations studied. The reference level of genotoxicity was not recorded at any of the stations revealing that in the sampling area fish were affected generally.",
Arsenic,1677529,"Differential Arsenic Mobilization from As-Bearing Ferrihydrite by Iron-Respiring Shewanella Strains with Different Arsenic Reducing Activities Abstract: Arsenic immobilization and release in the environment is significantly influenced by bacterial oxidation and reduction of arsenic and arsenic-bearing minerals. In this study, three metal-reducing bacteria, Shewanella oneidensis MR-1, Shewanella sp. HN-41, and Shewanella putrefaciens 200 which have diverse arsenate-reducing activities, were comparatively investigated in regard to reduction of an As-bearing ferrihydrite slurry. In the cultures of S. oneidensis MR-1 and strain HN-41 which are not capable of respiratory reduction of As(V) to As(III), arsenic was maintained predominantly in its pentavalent form, existing in poorly crystalline As-bearing ferrihydrite nanoparticles and formed small quantities of a stable ferrous arsenate (Fe3(AsO4)2) precipitate. However, in the culture of the As(V)-reducer, S. putrefaciens 200, As(V) was reduced to As(III) and a small fraction of As-bearing ferrihydrite nanoparticles were transformed into siderite nanoribbons that subsequently re-released(?) arsenic into the liquid phase. Our results indicated that release of arsenic and formation of diverse secondary nano-scale Fe-As minerals are closely related to the arsenic-reducing abilities of different bacteria specifically. Therefore bacterial arsenic reduction appears to significantly influence As mobilization in soils, minerals, and other Fe-rich environments.",
Arsenic,1337297,"Preparation and sorption studies of ?-cyclodextrin-chitosan-glutaraldehyde terpolymers Abstract: ?-Cyclodextrin-chitosan-glutaraldehyde terpolymers were synthesized by reacting variable weight fractions of ?-cyclodextrin (?-CD) and chitosan (Chi), with a constant amount of crosslinker (glutaraldehyde). The ?-CD:Chi:Glu terpolymer sorbents were characterized by FT-IR spectroscopy and TGA. The solid-solution sorption isotherms in aqueous solution for the copolymers were characterized using two spectroscopic methods (UV-Vis and ICAP-OES) for p-nitrophenol (PNP) and the arsenate oxoanion (HAsO(4)(2-)) at alkaline pH conditions. The Sips isotherm model was utilized to obtain sorption parameters at pH 8.5 and 295K (i.e. sorbent surface area, sorption capacity and removal efficiency) for each copolymer sorbent. The sorbent surface area estimates for the terpolymers at low (T1), medium (T2), and high (T3) weight fractions of ?-CD are listed in parentheses (m(2)g(-1)), as follows: T1 (161), T2 (51.2) and T3 (275). The removal efficiencies are dependent on the relative weight fraction of the polysaccharide components (i.e. ?-CD and Chi); whereas the removal efficiencies for p-nitrophenolate ranged between 7.3% and 28%, and H(2)AsO(4)(2-) ranged between 23% and 55%.",
Arsenic,1508695,"Importance of the oral arsenic bioaccessibility factor for characterising the risk associated with soil ingestion in a mining-influenced zone Abstract: Arsenic is a carcinogenic metalloid and the risks of accidental ingestion should therefore be borne in mind when assessing areas with high levels of this element. In this work, the concentrations of bioaccessible As in mining-influenced soils, in SE Spain are determined. The risk posed by the accidental ingestion is studied in two soil fractions (&lt;2mm and &lt;250?m), taking into consideration the possible uses of the soils (residential/agricultural) and possible receptors (adults and/or children). The properties and mineralogical composition of 26 soil samples are analysed. The results showed that the use of a conservative approach to calculate the Chemical Daily Intake (CDI) based on the total concentrations of arsenic, may overestimate the risk existing in the zone, leading to problems in the management of contaminated soils. The paper emphasises the importance of considering the amount of bioaccessible As in the &lt;250?m fraction before permitting land near temporary watercourses to be used for residential purposes, as beaches or for agriculture.",
Arsenic,1021723,"Comparative toxicity of arsenic metabolites in human bladder cancer EJ-1 cells Abstract: The human bladder is one of the primary target organs for arsenic-induced carcinogenicity, and arsenic metabolites in urine have been suspected to be directly involved in carcinogenesis. Thioarsenicals are commonly found in human and animal urine and are also considered to be highly toxic arsenic metabolites. The present study was performed to gain insight into the toxicity and accumulation of arsenic species found in urine, including arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylmonothioarsonic acid (MMMTA(V)), dimethylarsinic acid (DMA(V)), dimethylarsinous acid (DMA(III)), dimethylmonothioarsinic acid, (DMMTA(V)), and dimethyldithioarsinic acid (DMDTA(V)) in human bladder cancer EJ-1 cells. The order of cytotoxicity of these arsenic compounds in EJ-1 human bladder cancer cells was DMA(III), DMMTA(V) &gt; iAs(III) ? iAs(V) &gt; MMMTA(V) &gt; MMA(V), DMA(V), and DMDTA(V), indicating that the sulfur-containing DMMTA(V) was among the most toxic arsenic compounds similar to trivalent DMA(III). We further characterized the DNA damage, generation of highly reactive oxygen species (hROS), and expression of proteins p21 and p53 in cells after exposure to iAs(III), DMA(III), and DMMTA(V). Cellular exposure to DMMTA(V) resulted in reduced protein expression of p53 and p21, increased DNA damage, and increased intracellular hROS (hydroxyl radical). In contrast, iAs(III) significantly increased the protein expression of p21 and p53 and did not increase the hROS at the IC(50). Intracellular glutathione (GSH) was reduced by 60% after exposure to DMA(III) or DMMTA(V), suggesting that DMMTA(V) causes cell death through oxidative stress. In contrast, GSH levels increased in cells exposed to iAs(III), and hROS only increased after a long exposure to iAs(III). Our findings demonstrate that DMMTA(V) may be one of the most toxicologically potent arsenic species, relevant to arsenic-induced carcinogenicity in the urinary bladder.",
Arsenic,710817,"Arsenic exposure in pregnancy increases the risk of lower respiratory tract infection and diarrhea during infancy in Bangladesh Abstract: BACKGROUND: Previous studies have reported associations between prenatal arsenic exposure and increased risk of infant mortality. An increase in infectious diseases has been proposed as the underlying cause of these associations, but there is no epidemiological research to support the hypothesis. We evaluated the association between arsenic exposure in pregnancy and morbidity during infancy. METHODS: This prospective population-based cohort study included 1,552 live-born infants of women enrolled during 2002 -2004 in Matlab, Bangladesh. Arsenic exposure was assessed by the concentrations of metabolites of inorganic arsenic in maternal urine samples collected at gestational week 8 and 30. Information on symptoms of lower respiratory tract infection (LRTI) and diarrhea in infants was collected by 7-days recalls at monthly home visits. RESULTS: In total 115,850 person-days of observation were contributed by the infants over a 12 months follow-up period. The estimated risk of LRTI and severe LRTI increased by 69% (adjusted relative risk (RR) 1.69, 95% confidence intervals (CI): 1.36 - 2.09) and 54% (RR 1.54, 95% CI: 1.21 - 1.97), respectively, for infants of mothers with urinary arsenic concentrations in the highest quintile (262 - 977 µg/L, average of arsenic concentrations measured in early and late gestation) relative to those with exposure in the lowest quintile (<39 µg/L). The corresponding figure for diarrhea was 20% (RR 1.20, 95% CI: 1.01 - 1.43). CONCLUSIONS: Arsenic exposure during pregnancy was associated with increased morbidity in infectious diseases during infancy. Taken together with the previous evidence of adverse effects on health, the findings strongly emphasize the need to reduce arsenic exposure via drinking water.",
Arsenic,1017285,"Effects of occupational exposure to arsenic on the nervous system: Clinical and neurophysiological studies Abstract: <strong>OBJECTIVES: </strong>A number of metals, especially heavy metals, exhibit neurotoxic properties. Neurological and neurophysiological studies indicate that the functions of the central (CNS) and peripheral nervous system (PNS) may be impaired under conditions of exposure to arsenic (As). The aim of the present study was to assess the effects of inorganic arsenic on the central and peripheral nervous system.<br /><br /><strong>MATERIALS AND METHODS: </strong>The study covered a group of 21 male workers (mean age: 41.9 yr; SD: 7.6; range: 31-55 yr) employed in a copper smelting factory. Their employment duration ranged from 5 to 33 years (mean: 18.1 yr; SD: 7.8). Arsenic concentrations in workplace air amounted to 0.01003 mg/m3 on average (SD: 0.00866). Urine arsenic concentrations ranged from 3.48 to 23.63 ?g/l (mean: 11.91 ?g/l; SD: 9.5). The control group consisted of 16 males non-occupationally exposed to As, matched for gender, age and work shift pattern. The evaluation of neurological effects was based on the findings of neurological examination, electroencephalography (EEG), visual evoked potentials (VEPs) and electroneurography (ENeG).<br /><br /><strong>RESULTS: </strong>Clinical symptoms, such as sleeplessness or sleepiness, irritability, headache, painful spasms in extremity muscles, extremity paresthesia and pain, and muscular fatigue prevailed among functional disorders of the nervous system in workers chronically exposed to As. Neurological examination did not reveal any organic lesions in the CNS or PNS. In EEG records classified as abnormal, generalized changes were most common. VEP examinations revealed abnormalities in evoked response latency. Stimulation of the motor fibers of the peroneal and medial nerves resulted in a decreased amplitude of the motor potential. Stimulation of the sensory fibers of medial nerves brought about a decreased amplitude of the sensory potential and a lower conduction velocity of the sural nerves.<br /><br /><strong>CONCLUSION: </strong>The findings of the study indicate that exposure to As concentrations within the threshold limit values (TLV) can induce subclinical effects on the nervous system, especially subclinical neuropathy.",
Arsenic,8270,"Comparison of the urinary excretion of arsenic metabolites after a single oral dose of sodium arsenite, monomethylarsonate, or dimethylarsinate in man Abstract: The urinary elimination of the metabolites of arsenic has been followed up as a function of time in volunteers who ingested a single oral dose of arsenic (500 ug As) either as sodium arsenite (Asi), monomethylarsonate (MMA), or cacodylate (DMA). The excretion rate increased in the order Asi < DMA < MMA. After 4 days, the amount of arsenic excreted in urine represents 46, 78, and 75% of the ingested dose in the case of Asi, MMA and DMA, respectively. With regard to the in vivo biotransformations, it is concluded that DMA is excreted unchanged; MMA is slightly (13%) methylated into DMA while roughly 75% of the arsenic excreted after ingestion of Asi is methylated arsenic (about 1/3 as MMA and about 2/3 as DMA).",
Arsenic,627077,"Changes in gene expression profiles in response to selenium supplementation among individuals with arsenic-induced pre-malignant skin lesions Abstract: The molecular basis and downstream targets of oral selenium supplementation in individuals with elevated risk of cancer due to chronic exposure from environmental carcinogens has been largely unexplored. In this study, we investigated genome-wide differential gene expression in peripheral blood mononuclear cells (PBMC) from individuals with pre-malignant arsenic (As)-induced skin lesions before and after 6 months daily oral supplementation of 200 microg L-selenomethionine. The Affymetrix GeneChip Human 133A 2.0 array, containing probes for 22,277 gene transcripts, was used to assess gene expression. Three different normalization methods, RMA (robust multi-chip analysis), GC-RMA and PLIER (Probe logarithmic intensity error), were applied to explore differentially expressed genes. We identified a list of 28 biologically meaningful, significantly differentially expressed genes. Genes up-regulated by selenium supplementation included TNF, IL1B, IL8, SOD2, CXCL2 and several other immunological and oxidative stress-related genes. When mapped to a biological association network, many of the differentially expressed genes were found to regulate functional classes such as fibroblast growth factor, collagenase, matrix metalloproteinase and stromelysin-1, and thus, considered to affect cellular processes like apoptosis, proliferation and others. Many of the significantly up-regulated genes following selenium-supplementation were previously found by us to be down-regulated in a different set of individuals with As-induced skin lesions compared to those without. In conclusion, findings from this study may elucidate the biological effect of selenium supplementation in humans. Additionally, this study suggests that long-term selenium supplementation may revert some of the gene expression changes presumably induced by chronic As exposure in individuals with pre-malignant skin lesions.",
Arsenic,627149,"Gene expression levels in normal human lymphoblasts with variable sensitivities to arsenite: Identification of GGT1 and NFKBIE expression levels as possible biomarkers of susceptibility Abstract: Drinking arsenic-contaminated water is associated with increased risk of neoplasias of the skin, lung, bladder and possibly other sites, as well as other diseases. Earlier, we showed that human lymphoblast lines from different normal unexposed donors showed variable sensitivities to the toxic effects of arsenite. In the present study, we used microarray analysis to compare the basal gene expression profiles between two arsenite-resistant (GM02707, GM00893) and two arsenite-sensitive lymphoblast lines (GM00546, GM00607). A number of genes were differentially expressed in arsenite-sensitive and arsenite-resistant cells. Among these, gamma-glutamyltranspeptidase 1 (GGT1) and NF kappa B inhibitor-epsilon (NFKBIE) showed higher expression levels in arsenite-resistant cells. RT-PCR analysis with gene-specific primers confirmed these results. Reduction of GGT1 expression level in arsenite-resistant lymphoblasts with GGT1-specific siRNA resulted in increased cell sensitivity to arsenite. In conclusion, we have demonstrated for the first time that expression levels of GGT1 and possibly NFKBIE might be useful as biomarkers of genetic susceptibility to arsenite. Expression microarrays can thus be exploited for identifying additional biomarkers of susceptibility to arsenite and to other toxicants.",
Arsenic,744836,"Merkel cell carcinoma and chronic arsenicism Abstract: Arsenic is a well-documented human carcinogen. Bowen's disease, squamous cell carcinoma, and basal cell carcinoma are the most common skin cancers found in patients exposed to arsenic over the long term. Merkel cell carcinoma has been documented in Taiwanese patients who resided in an endemic area of black foot disease, another condition found in patients with chronic arsenicism. We collected all cases of Merkel cell carcinoma diagnosed at two medical centers in Taiwan (N = 11) to find a possible association between chronic arsenicism and Merkel cell carcinoma. In our study 6 of the 11 patients were residents of the endemic areas for chronic arsenicism.",
Arsenic,2345711,"Chemical markers of occupational exposure to teak wood dust Abstract: A novel high-performance liquid chromatographic/ultraviolet method was developed to detect lapachol (LP) and deoxylapachol (DLP) in wood dust as chemical markers of teak wood (a suspected human carcinogen). The specificity of this analysis was determined by noting the absence of LP and DLP in 12 other specimens of different woods belonging to the angiosperm family. The consistency was examined by analyzing teak from three different sources, where the percentages (wt/wt) of the chemicals ranged from 0.006 to 0.261 for LP and from 0.038 to 0.497 for DLP, respectively. Although the LP and DLP components of teak varied according to source, a very high correlation coefficient (r (2) &gt; 0.98 always) was found between the content of the two markers in the bulk specimens and in bulk dust derived from them. The method was then applied to teak dust collected on polyvinylchloride filters from aerosol in an exposure chamber in the range of mass loadings between 0.03 and 3.65mg, which corresponds to a dust exposure between 0.124 and 8.703mg m(-3) for a sampling time of 2h. A field test was also carried out in a small factory where teak was used. A good correlation was confirmed between LP and DLP versus the dust collected on the filter in both cases. LP and DLP can be markers to estimate the true quantities of teak dust inhaled in a workplace with mixed wood dust, provided the results are matched to the content of LP and DLP in the bulk wood. LP and DLP have also been proposed as the agents responsible for allergic reaction to teak dust. Therefore, it would be useful to evaluate the exposure to these two substances even without a relationship to teak dust exposure.",
Arsenic,1338731,"Environmental exposure to arsenic and cadmium during pregnancy and fetal size: A longitudinal study in rural Bangladesh Abstract: Prenatal exposures to arsenic (As) and cadmium (Cd) have been associated with decreased size at birth. We here studied associations of prenatal As and Cd exposures with multiple fetal size parameters measured by ultrasound in gestational week (GW) 14 and 30 in a population-based mother-child cohort in rural Bangladesh. We measured As (n=1929) and Cd (n=1616) in urine during pregnancy. In the longitudinal evaluation of combined exposure, urinary Cd (UCd) showed an inverted U-shaped association (turning-point 1.5?g Cd/L) with all fetal size parameters, while UAs showed no significant association. Cross-sectional analyses indicated that associations with UCd were somewhat stronger in early gestation. Stratification indicated stronger associations between UCd and fetal size in girls than in boys, and in poorer than in richer families, while UAs was weakly associated with fetal size in boys. In conclusion, particularly Cd, but also As, appeared to influence fetal development in a sex-dependent manner.",
Arsenic,2278619,"Toxic metal levels in children residing in a smelting craft village in Vietnam: a pilot biomonitoring study Abstract: <strong>BACKGROUND: </strong>In Vietnam, environmental pollution caused by small-scale domestic smelting of automobile batteries into lead ingot is a growing concern. The village of Nghia Lo is a smelting craft village located roughly 25 km southeast of Hanoi in the Red River Delta. Despite the concern of toxic metal exposure in the village, biomonitoring among susceptible populations, such as children, has not been previously conducted. The aim of this study was to determine the body burden of toxic metals in children residing in a smelting craft village.<br /><br /><strong>METHODS: </strong>Twenty children from Nghia Lo, Vietnam, ages 18 months to four years were selected for capillary whole blood and toenail biomonitoring. Whole blood lead levels (BLLs) were measured using a portable lead analyzer, and toenail levels of arsenic, cadmium, chromium, lead, manganese, and mercury were analyzed with inductively coupled plasma-mass spectrometry.<br /><br /><strong>RESULTS: </strong>The findings show that all of the 20 children had detectable BLLs, and every child had levels that exceeded the Centers for Disease Control and Prevention guideline level of 5 ?g/dL. Eighty percent of tested subjects had BLLs higher than 10 ?g/dL. Five children (25%) had BLLs greater than 45 ?g/dL, the level of recommended medical intervention. In addition to blood lead, all of the children had detectable levels of arsenic, cadmium, chromium, lead, manganese, and mercury in toenail samples. Notably, average toenail lead, manganese, and mercury levels were 157 ?g/g, 7.41 ?g/g, and 2.63 ?g/g respectively, well above levels previously reported in children. Significant Spearman's rank correlations showed that there were relationships between blood and toenail lead levels (r?=?0.65, p?&lt;?0.05), toenail levels of lead and cadmium (r?=?0.66, p?&lt;?0.05), and toenail levels of manganese and chromium (r?=?0.72, p?&lt;?0.001). Linear regression showed that reducing the distance to the nearest active smelter by half was associated with a 116% increase in BLL (p?&lt;?0.05).<br /><br /><strong>CONCLUSIONS: </strong>The results suggest that children in battery recycling and smelting craft villages in Vietnam are co-exposed to toxic metals. There is an urgent need for mitigation to control metal exposure related to domestic smelting.",
Arsenic,1023898,"Development and testing of a green fluorescent protein-based bacterial biosensor for measuring bioavailable arsenic in contaminated groundwater samples Abstract: A green fluorescent protein (GFP)-based bacterial biosensor for the detection of bioavailable As(III), As(V), and Sb(III) was developed and characterized. The biosensor strain Escherichia coli DH5alpha (pVLAS1) was developed based on the expression of gfp under the control of the ars promoter and the arsR gene of Staphylococcus aureus plasmid pI258. Strain DH5alpha (pVLAS1) responded mainly to As(III), As(V), and Sb(III), with the lowest detectable concentrations being 0.4, 1, and 0.75 microM, respectively, during a 2-h exposure and 0.1 microM for all three metal ions with an 8-h induction period. To assess its applicability for analyzing environmentally relevant samples, the biosensor was field-tested on shallow-well groundwater for which contaminant levels were known. Our results demonstrate that the nonpathogenic bacterial biosensor developed in the present study is useful and applicable in determining the bioavailability of arsenic with high sensitivity in contaminated groundwater samples, and they suggest a potential for its inexpensive application in field-ready tests.",
Arsenic,656692,"Occurrence of arsenicosis in a rural village of Cambodia Abstract: Ninety-seven subjects belonging to 40 families in a village in Cambodia were examined in a health camp where all the cases with skin disease assembled. These people had evidences of chronic arsenic exposure from reports of testing of water samples and of hair and/or nail studied. Seventy cases were diagnosed to be suffering from arsenicosis (Clinically and laboratory confirmed according to WHO criteria) as all these cases had evidences of pigmentation and/or keratosis characteristic of arsenicosis and history of exposure of arsenic contaminated water and/or elevated level of arsenic in hair and/or in nail. Highest number of cases belonged to age group of 31 to 45 yrs, both the sexes are more or less affected equally. Evidence of both pigmentation and keratosis were found in 60 cases (85.7%) while only pigmentation and only keratosis was found in 6 (8.5%) and 4 (5.7%) cases respectively. It was interesting to find 37.04% of children below the age of 16 years had skin lesions of arsenicosis. The youngest child having definite evidence of keratosis and pigmentation was aged 8 years, though two children aged 4 and 5 yrs had feature of redness and mild thickening of the palms. The minimum and maximum arsenic values detected in the nails were 1.06 and 69.48 mg/Kg respectively and the minimum and maximum arsenic values in hair were 0.92 and 25.6 mg/Kg respectively. No correlation was observed between arsenic concentration in drinking water and arsenic level in nail and hair. This is the first report of clinical and laboratory confirmed cases of arsenicosis in Cambodia.",
Arsenic,1508586,"Genetic variations creating microRNA target sites in the FXN 3'-UTR affect frataxin expression in Friedreich ataxia Abstract: Friedreich's ataxia (FRDA) is a severe neurodegenerative disease caused by GAA repeat expansion within the first intron of the frataxin gene. It has been suggested that the repeat is responsible for the disease severity due to impaired transcription thereby reducing expression of the protein. However, genotype-phenotype correlation is imperfect, and the influence of other gene regions of the frataxin gene is unknown. We hypothesized that FRDA patients may harbor specific regulatory variants in the 3'-UTR. We sequenced the 3'-UTR region of the frataxin gene in a cohort of 57 FRDA individuals and 58 controls. Seven single nucleotide polymorphisms (SNPs) out of 19 were polymorphic in our case-control sample. These SNPs defined several haplotypes with one reaching 89% of homozygosity in patients versus 24% in controls. In another cohort of 47 FRDA Reunionese patients, 94% patients were found to be homozygous for this haplotype. We found that this FRDA 3'-UTR conferred a 1.2-fold decrease in the expression of a reporter gene versus the alternative haplotype configuration. We established that differential targeting by miRNA could account for this functional variability. We specifically demonstrated the involvement of miR-124 (i.e hsa-mir-124-3p) in the down-regulation of FRDA-3'-UTR. Our results suggest for the first time that post-transcriptional regulation of frataxin occurs through the 3'-UTR and involves miRNA targeting. We propose that the involvement of miRNAs in a FRDA-specific regulation of frataxin may provide a rationale to increase residual levels of frataxin through miRNA-inhibitory molecules.",
Arsenic,1519031,"Arsenic toxicity in garden cress (Lepidium sativum Linn.): significance of potassium nutrition Abstract: In a hydroponic culture, experiments were performed to study the influence of potassium (K) supplementation (0, 20, 40, 60, 80, and 100 mg L(-1)) on the arsenic (As; 0, 8, and 10 mg L(-1))-accrued changes in growth traits (plant biomass, root-shoot length) and the contents of lepidine, As and K, in garden cress (Lepidium sativum Linn.) at 10 days after treatment. The changes in these traits were correlated with shoot proline content, protein profile, and the activities of antioxidant enzymes namely superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione reductase (GR, EC 1.8.1.7), and ascorbate peroxidase (APX, EC 1.11.1.11). In general, As-alone treatments significantly decreased the growth traits but lead to significant enhancements in shoot proline and enzyme activities. K-supplementation to As-treated L. sativum seedlings decreased shoot-As content, reduced As-induced decreases in growth traits but enhanced the content of shoot proline, and the activities of the studied enzymes maximally with K100 + As8 and As10 mg L(-1). Both 8 and 10 mg L(-1) of As drastically downregulated the shoot proteins ranging from 43-65 kDa. With As10 mg L(-1), there was a total depletion of protein bands below 23 kDa; however, K80 mg L(-1) maximally recovered and upregulated the protein bands. Additionally, protein bands were downregulated (at par with As-alone treatment) above K80 mg L(-1) level. Interestingly, As-stress increased lepidine content in a dose-dependent manner which was further augmented with the K-supplementation. It is suggested that K protects L. sativum against As-toxicity by decreasing its accumulation and strengthening antioxidant defense system and protein stability.",
Arsenic,710831,"Arsenic induces pancreatic ?-cell apoptosis via the oxidative stress-regulated mitochondria-dependent and endoplasmic reticulum stress-triggered signaling pathways Abstract: Arsenic (As), a ubiquitous toxic metal, is an important environmental and industrial pollutant throughout the world. Inorganic As (iAs) is usually more harmful than organic ones and with a high risk of diabetes incidence by exposure. However, the toxicological effects of iAs on growth and function of pancreatic ?-cells still remain unclear. Here, we found that iAs significantly decreased insulin secretion and cell viability, and increased ROS and MDA formation in pancreatic ?-cell-derived RIN-m5F cells. iAs also induced the increases in sub-G1 hypodiploids, annexin V-Cy3 binding, and caspase-3 activity in RIN-m5F cells, indicating that iAs could induce ?-cell apoptosis. Moreover, iAs induced MAPKs activation, mitochondria dysfunction, p53 up-regulation, Bcl-2 and Mdm-2 down-regulation, PARP, and caspase cascades, which displayed features of mitochondria-dependent apoptotic signals. In addition, exposure of RIN-m5F cells to iAs, could trigger ER stress as indicated by the enhancement in ER stress-related molecules induction (such as GRP78, GRP94, CHOP, and XBP1), procaspase-12 cleavage, and calpain activation. The iAs-induced apoptosis and its-related signalings could be effectively reversed by antioxidant N-acetylcysteine. We next observed that exposure of mice to iAs in drinking water for 6 consecutive weeks significantly decreased decreased the plasma insulin, elevated glucose intolerance and plasma lipid peroxidation, and induced islet cells apoptosis, which accompanied with arsenic accumulation in the whole blood and pancreas. N-acetylcysteine effectively antagonized the iAs-induced responses in mice. Taken together, these results suggest that iAs-induced oxidative stress causes pancreatic ?-cells apoptosis via the mitochondria-dependent and ER stress-triggered signaling pathways.",
Arsenic,734986,"Epigenetic remodeling during arsenical-induced malignant transformation Abstract: Humans are exposed to arsenicals through many routes with the most common being in drinking water. Exposure to arsenic has been associated with an increase in the incidence of cancer of the skin, lung and bladder. Although the relationship between exposure and carcinogenesis is well documented, the mechanisms by which arsenic participates in tumorigenesis are not fully elucidated. We evaluated the potential epigenetic component of arsenical action by assessing the histone acetylation state of 13 000 human gene promoters in a cell line model of arsenical-mediated malignant transformation. We show changes in histone H3 acetylation occur during arsenical-induced malignant transformation that are linked to the expression state of the associated gene. DNA hypermethylation was detected in hypoacetylated promoters in the select cases analyzed. These epigenetic changes occurred frequently in the same promoters whether the selection was performed with arsenite [As(III)] or with monomethylarsonous acid, suggesting that these promoters were targeted in a non-random fashion, and probably occur in regions important in arsenical-induced malignant transformation. Taken together, these data suggest that arsenicals may participate in tumorigenesis by altering the epigenetic terrain of select genes.",
Arsenic,2298681,"Prenatal arsenic exposure and shifts in the newborn proteome: Inter-individual differences in tumor necrosis factor (TNF)-responsive signaling Abstract: Exposure to inorganic arsenic (iAs) early in life is associated with adverse health effects in infants, children, and adults, and yet the biological mechanisms that underlie these effects are understudied. The objective of this research was to examine the proteomic shifts associated with prenatal iAs exposure using cord blood samples isolated from 50 newborns from Gómez Palacio, Mexico. Levels of iAs in maternal drinking water (DW-iAs) and the sum of iAs and iAs metabolites in maternal urine (U-tAs) were determined. Cord blood samples representing varying iAs exposure levels during the prenatal period (DW-iAs ranging from <1 to 236 ?g As/L) were analyzed for altered expression of proteins associated with U-tAs using a high throughput, antibody-based method. A total of 111 proteins were identified that had a significant association between protein level in newborn cord blood and maternal U-tAs. Many of these proteins are regulated by tumor necrosis factor (TNF) and are enriched in functionality related to immune/inflammatory response and cellular development/proliferation. Inter-individual differences in proteomic response were observed in which 30 newborns were activators, displaying a positive relationship between protein expression and maternal U-tAs. For 20 repressor newborns, a negative relationship between protein expression level and maternal U-tAs was observed. The activator/repressor status was significantly associated with maternal U-tAs and head circumference in newborn males. These results may provide a critical groundwork for understanding the diverse health effects associated with prenatal arsenic exposure and highlight inter-individual responses to arsenic that likely influence susceptibility to adverse health outcomes.",
Arsenic,1519222,Arsenic exposure and glutamate-induced gliotransmitter release from astrocytes Abstract: ,
Arsenic,2279519,"Menin is required for optimal processing of the micro-RNA let-7a Abstract: Multiple Endocrine Neoplasia Type I (MEN1) is an inherited syndrome that includes susceptibility to pancreatic islet hyperplasia. This syndrome results from mutations in the MEN1 gene, which encodes menin protein. Menin interacts with several transcription factors, including JunD, and inhibits their activities. However, the precise mechanism by which menin suppresses gene expression is not well understood. Here, we show that menin interacts with arsenite-resistant protein 2 (ARS2), a component of the nuclear RNA CAP-binding complex that is crucial for biogenesis of certain miRNAs including let-7a. The levels of primary-let-7a (pri-let-7a) are not affected by menin; however, the levels of mature let-7a are substantially decreased upon Men1-excision. Let-7a targets, including Insr and Irs2, pro-proliferative genes that are crucial for insulin-mediated signaling, are upregulated in Men1-excised cells. Inhibition of let-7a using anti-miRNA in wild type cells is sufficient to enhance the expression of Insulin Receptor Substrate 2 (IRS2) to levels observed in Men1-excised cells. Depletion of menin impaired the processing of pri-miRNA to pre-miRNA. As IRS2 is known to mediate insulin signaling and insulin/mitogen-induced cell proliferation, these findings collectively unravel a novel mechanism whereby menin suppresses cell proliferation, at least partly by promoting the processing of certain miRNAs, including let-7a, leading to suppression of Irs2 expression and insulin signaling.",
Arsenic,67931,"Arsenic induces and enhances rat hepatic metallothionein production in vivo Abstract: Metallothionein genes (MT) are inducible by a variety of agents, including heavy metals. We report the induction of MT expression by arsenite (As3+) in rat liver in vivo. As3+ (but not arsenate [As5+]) injection increased MT protein and MT-1 and MT-2 mRNA accumulation in liver only, but not in kidney or pancreas. In addition, As3+ enhanced zinc-induced MT protein accumulation in liver without any increase in MT mRNA levels. These data indicate that arsenic may increase MT expression either directly (by inducing MT mRNA accumulation), or indirectly by altering post-transcriptional events. This constitutes an unusual mechanism of enhancement of MT gene expression and appears to be mediated by processes not specifically associated with binding of arsenite to MT in vivo.",
Arsenic,1033967,"[Late skin symptoms of arsenic poisoning in the arsenic endemy in Bugac-Alsómonostor] Abstract: The population in an arsenic polluted area of Hungary was studied in respect of dermatological signs. Melanosis was observed in 23,75 per cent and keratosis in 10,83 per cent. Vitiligo has been present in 3 per cent of the population being partly associated to melanosis and partly independent. The observations suggest that arsenic does not only induce malignant neoplasms but also enhances development of benign skin tumours.",
Arsenic,1027629,"Investigation of arsenic exposure from soil at a superfund site Abstract: The purpose of this study was to determine if significant arsenic exposure was occurring at a Superfund site with elevated surface soil arsenic concentrations. A second objective was to determine the statistical relationship between the various methods of measuring arsenic exposure in humans. Random urine, 24-hr urine, hair, and fingernail samples were collected at the end of the workweek from 40 employees at an active pesticide manufacturing facility which had formerly produced arsenical pesticides. There was no indication of adverse health effects among the employees attributable to arsenic exposure. Mean urinary, hair, and fingernail concentrations of arsenic were well within normal values and indicated that significant arsenic exposure was not occurring among the employees. Random and 24-hr urine measurements were significantly correlated. Hair and fingernail results also were significantly correlated. Urine results did not correlate well with hair or fingernail results. Results of this study suggest that although there may be some individual variation, random and 24-hr urine arsenic results are not substantially different. For the purpose of screening for arsenic exposure, random urine samples may be an adequate and preferable test for those populations in equilibrium with their environment.",
Arsenic,1026731,"Effects of low-level arsenic exposure on the developmental toxicity of anilofos in rats Abstract: In view of the increased use of anilofos for crop protection and ever increasing arsenic levels in drinking water in many countries, the coexistence of arsenic and anilofos in the environment is a reality and simultaneous exposure of humans and animals to these contaminants could be potentially hazardous. The aim of the present study was to examine whether coexposure to arsenic at the groundwater contamination level could alter the embryofetal toxicity of anilofos in rat model. Anilofos (100 mg kg(-1) day(-1)) and sodium arsenite (1 mg arsenic kg(-1) day(-1)) were administered by gavage either individually or in combination to the pregnant rats from day 6 to day 15 of gestation. Arsenic did not produce any significant effects either on maternal or fetal parameters at the given dose. Anilofos alone significantly decreased maternal weight gain, feed and water intakes, gravid uterine weights, number of live fetuses and fetal body weights and increased resorptions. There were increased incidences of gross, skeletal and visceral anomalies in the fetuses of anilofos-treated group. The main skeletal abnormality was increased intercostal space, while the visceral anomaly was an interventricular septal defect. Treatment with the combination of arsenic and anilofos significantly enhanced the fetal changes with much greater magnitude compared with the effects produced by anilofos alone. Anomalies such as midfacial cleft, exencephaly and anophthalmia were seen only in the fetuses of the combination group. The results show that anilofos interferes with embryofetal development and coexposure with arsenic at environmentally realistic concentrations produces additive or synergistic effects on the developmental toxicity of anilofos in rats.",
Arsenic,1798808,"In-situ assessment of metal contamination via portable X-ray fluorescence spectroscopy: Zlatna, Romania Abstract: Zlatna, Romania is the site of longtime mining/smelting operations which have resulted in widespread metal pollution of the entire area. Previous studies have documented the contamination using traditional methods involving soil sample collection, digestion, and quantification via inductively coupled plasma atomic emission spectroscopy or atomic absorption. However, field portable X-ray fluorescence spectroscopy (PXRF) can accurately quantify contamination in-situ, in seconds. A PXRF spectrometer was used to scan 69 soil samples in Zlatna across multiple land use types. Each site was georeferenced with data inputted into a geographic information system for high resolution spatial interpolations. These models were laid over contemporary aerial imagery to evaluate the extent of pollution on an individual elemental basis. Pb, As, Co, Cu, and Cd exceeded governmental action limits in &gt;50% of the sites scanned. The use of georeferenced PXRF data offers a powerful new tool for in-situ assessment of contaminated soils.",
Arsenic,1070377,"Molecular analysis of spatial variation of iron-reducing bacteria in riverine alluvial aquifers of the Mankyeong River Abstract: Alluvial aquifers are one of the mainwater resources in many countries. Iron reduction in alluvial aquifers is often a major anaerobic process involved in bioremediation or causing problems, including the release of As trapped in Fe(III) oxide. We investigated the distribution of potential iron-reducing bacteria (IRB) in riverine alluvial aquifers (B1, B3, and B6 sites) at the Mankyeong River, Republic of Korea. Inactive iron reduction zones, the diversity and abundance of IRB can be examined using a clone library and quantitative PCR analysis of 16S rRNA genes. Geobacter spp. are potential IRB in the iron-reducing zone at the B6 (9 m) site, where high Fe(II) and arsenic (As) concentrations were observed. At the B3 (16 m) site, where low iron reduction activity was predicted, a dominant clone (10.6%) was 99% identical in 16S rRNA gene sequence with Rhodoferax ferrireducens. Although a major clone belonging to Clostridium spp. was found, possible IRB candidates could not be unambiguously determined at the B1 (18 m) site. Acanonical correspondence analysis demonstrated that, among potential IRB, only the Geobacteraceae were well correlated with Fe(II) and As concentrations. Our results indicate high environmental heterogeneity, and thus high spatial variability, in thedistribution of potential IRB in the riverine alluvial aquifersnear the Mankyeong River.",
Arsenic,1340883,"Arsenite-induced apoptosis of human neuroblastoma cells requires p53 but occurs independently of c-Jun Abstract: Arsenite treatment of human SH-SY5Y neuroblastoma cells leads to an upregulation of caspase-3/7 activity and to the fragmentation of chromatin that is accompanied by elevated p53 and c-Jun levels. Expression of a truncated mutant of p53, p53DD, which interfered with the oligomerization of p53, suppressed the arsenite-induced upregulation of caspase-3/7 activity and the fragmentation of chromatin, indicating that p53 is required for arsenite-induced cell death. These data were corroborated by knockdown experiments of p53 following expression of a p53-specific short hairpin RNA. Likewise, expression of either p53DD or knockdown of p53 prevented caspase-3/7 activation and chromatin fragmentation induced by nutlin-3, a compound that prevents the interaction between p53 and the E3 ubiquitin ligase MDM2. Transcriptional upregulation of a chromatin-embedded p53-responsive reporter gene in either arsenite or nutlin-3 stimulated neuroblastoma cells revealed that the transcriptional activity of p53 was increased under these conditions. Expression of a c-Jun-specific short hairpin RNA failed to impair arsenite-induced caspase-3/7 activation and fragmentation of chromatin. Likewise, inhibition of c-Jun target gene expression by expression of a dominant-negative mutant of c-Jun did not interfere with arsenite-induced caspase-3/7 activation and chromatin fragmentation. However, this approach successfully reduced caspase-3/7 activity induced as a result of forced expression of a constitutively active mutant of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase (MEKK)-1. Together, these data show that the upregulation of p53 is causally linked with arsenite-induced cell death in neuroblastoma cells, whereas the upregulation of c-Jun is not part of this apoptotic signaling cascade.",
Arsenic,1022091,"Arsenic accumulation and resistance mechanism in Panax notoginseng, a traditional rare medicinal herb Abstract: Panax notoginseng, a traditional rare Chinese medicinal herb, was recently found to bring health risk to consumers, mainly because soil in its major plantation area was contaminated by arsenic (As). We investigated the effect of soil As pollution on the growth and As uptake of pot-cultured P. notoginseng, and the associated mechanisms of As stressed response. Results showed that, comparing with P. notoginseng growing in a low-As soil, the root, stem, and leaf biomasses of those growing in a high-As soil significantly reduced by 0.75, 0.09 and 0.21gseedling(-1), respectively. Arsenic concentrations in roots, stems and leaves of the seedlings growing in high-As soil were 22, 15 and 3times higher than those growing in low-As soil, respectively. Regardless of the soil As concentration, As existed in plants mainly as As(III), suggesting that the reduction of As(V) is a key step in As metabolism. Arsenic was distributed primarily in cell walls (51.7% for plants growing in the low-As soil, and 51.5% in the high-As soil), followed by cytoplasm supernatant, with cell organelles containing the least As. Compared with plants growing in the low-As soil, those in the high-As soil had increased superoxide dismutase and peroxidase activities in their roots, stems, and leaves, which would be associate with improving the resistance of P. notoginseng to As stress. The results suggest that there exists some special mechanisms of As-tolerance in P. notoginseng and the study is of significance in developing measures to reduce As in the herb.",
Arsenic,627967,"Protective effect of Mentha piperita against arsenic-induced toxicity in liver of Swiss albino mice Abstract: The protective role of leaves of Mentha piperita Linn (Mint) was studied in adult Swiss albino mice against arsenic-induced hepatopathy. The animals were divided into four groups. Group I: only vehicle (0.9% NaCl) was administered. Group II: the animals received Mentha leaf extract (1 g/kg body weight per day) orally for 30 days. Group III: animals were treated with sodium arsenite (4 mg/kg body weight) intraperitoneally in 0.9% NaCl. Group IV: animals were given Mentha extract for 10 consecutive days prior to sodium arsenite treatment and continuously for 30 days after sodium arsenite treatment. The animals from the above groups were killed at various time-points, and body weight and liver weight were measured. The biochemical estimation of lipid peroxidation (LPO), reduced glutathione (GSH), lactate dehydrogenase (LDH), acid phosphatase (ACP), and alkaline phosphatase (ALP) in liver and serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) in serum were done. In the arsenic-treated group there was a significant increase in ACP, ALP, SGOT, SGPT and LPO content, whereas a significant decrease was recorded in body weight, liver weight, GSH and LDH activity in liver. Pre- and post-treatment of Mentha with arsenic significantly alters the biochemical parameters in liver. A significant decline in ACP, ALP, SGOT, SGPT and LPO content was observed. However, a significant increase in body weight, liver weight, GSH content and LDH activity in liver was estimated. The results indicate that the Mentha extract may be useful in reducing the side effects of arsenic-induced hepatopathy.",
Arsenic,1508538,"Arsenic bioaccessibility in gold mine tailings of Delita, Cuba Abstract: A bioaccessibility test was carried out in four tailings collected at a former mining area in Delita, Cuba. A previous risk assessment study identified arsenic (As) as the main critical contaminant in this area and showed that the tailings had high As concentrations (up to 3.5%). This study aimed at: (i) evaluating As bioaccessibility in four tailings (R1, R2, R3 and R4) from a gold mining area to obtain a better health risk estimate; and, (ii) identifying the mineral phases responsible for most of the bioaccessible As using XRD, SEM-EDS, and XAS. The results showed that bioaccessible As in the tailings ranged from 0.65 to 40.5%. The main factors influencing As bioaccessibility were a high occurrence of amorphous iron arsenate; occurrence, even at low content, of iron oxyhydroxides and stability of mineral phases in the environment of the gastrointestinal tract. Although arsenopyrite, arsenates and goethite were confirmed by mineralogical methods such as optical microscopy, XRD, and SEM-EDS, XAS showed that scorodite-oxidation state As(+V)-was dominant in most of the tailings. This confirms that the low bioaccessibility of As in most of the tailings is due to the slow kinetics of As release from scorodite.",
Arsenic,2278506,"Multiproxy investigation of a Holocene sedimentary sequence near Ferrara (Italy): Clues on the physiographic evolution of the eastern Padanian Plain Abstract: Purpose This paper investigates soils and sediments from the eastern Padanian Plain (northern Italy) in order to delineate the physiographic evolution of the area. <br> <br>Materials and methods We present new geochemical, mineralogical and textural analyses of alluvial sediments collected from a 13-m-deep section located a few kilometres south of Ferrara. The chronology of the related depositional events is provided from C-14 dating of tree trunks buried at depths of ca. 9 m and organic matter from the underlying horizons. <br> <br>Results and discussion The data indicate that (1) the upper part of the sequence (down to depths of 9 m) includes sediments characterized by low nickel-chromium (Ni-Cr) concentrations ascribed to the alluvial deposits of the river Reno, deposited in the last 400 years; (2) buried soils (depths of 9-10.5 m) developed on Ni-Cr-rich sediments related to the river Po; and (3) the deeper facies (depths of 10.5-13 m) are CaCO3-free and characterized by higher amounts of organic carbon, sulphur and arsenic, reflecting episodic lacustrine/marsh environments. These wetlands probably developed in the area during the Iron and Roman ages, persisting up to the Middle Ages. <br> <br>Conclusions The data provide a contribution to the understanding of the evolution of the river network during the last 3,000 years and provide insights on the related paleohydrological framework that can be useful for geographical and historical reconstructions of the area. Results highlight the importance of investigating alluvial sediments to elucidate (1) fluctuations of environmental conditions and (2) anthropogenic impacts on the natural landscape.",
Arsenic,1358370,"Cancer of the nose in nickel workers Abstract: Epidemiologic aspects of nasal cancer in nickel (7440020) refinery workers at the Clydach refinery in Wales are reviewed. The refinery had been in operation from 1902 until 1932 when the observation was made that 10 cases of cancer of the interior of the nose had occurred in the previous 11 years. Subsequent reports on the subject are summarized. Up to December 1957, 131 cases of cancer of the lung and 61 cases of nasal cancer were discovered among workers employed at the facility, which had a working population of 950. As cancer of the lung is common in the general population and cancer of the nose is very rare, it is accepted that the incidence of cancer of the nose is the more reliable index of exposure to a specific carcinogenic agent during nickel refining. Research shows that nickel workers in South Wales have a significantly increased risk of dying of cancer of the nose or lung. Clinically, the cancer begins as nasal inflammation or papillomata or both. The papillomata become malignant and invade nasal sinuses, particularly the ethmoid. Death follows within 2 years. Cases occur between 6 and 42 years after initial employment, the peak incidence being in workers who have been at the work place for 20 to 25 years. The disease affects process workers almost exclusively. Carcinogenic agents considered responsible for these cancers are discussed. Radioactive substances, arsenic (7440382), and nickel-carbonyl (13463393) have all been considered. Specialists believe that arsenic in the sulfuric-acid used for extraction of copper-sulfate from matter is the noxious agent. Sulfuric-acid used since 1924 has been practically free of arsenic. Facilities have also been made dust free. The author concludes that the occupational hazard to which nickel workers were exposed has been brought under control at the Clydach Refinery.",
Arsenic,453484,"Response of arsenic-induced oxidative stress, DNA damage, and metal imbalance to combined administration of DMSA and monoisoamyl-DMSA during chronic arsenic poisoning in rats Abstract: Arsenic and its compounds cause adverse health effects in humans. Current treatment employs administration of thiol chelators, such as meso-2,3-dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), which facilitate its excretion from the body. However, these chelating agents are compromised by number of limitations due to their lipophobic nature, particularly in case of chronic poisoning. Combination therapy is a new approach to ensure enhanced removal of metal from the body, reduced doses of potentially toxic chelators, and no redistribution of metal from one organ to another, following chronic metal exposure. The present study attempts to investigate dose-related effects of two thiol chelators, DMSA and one of its new analogues, monoisoamyl dimercaptosuccinic acid (MiADMSA), when administered in combination with the aim of achieving normalization of altered biochemical parameters suggestive of oxidative stress and depletion of inorganic arsenic following chronic arsenic exposure. Twenty-five adult male Wistar rats were given 25 ppm arsenic for 10 weeks followed by chelation therapy with the above chelating agents at a dose of 0.3 mmol/kg (orally) when administered individually or 0.15 mmol/kg and 0.3 mmol/kg (once daily for 5 consecutive days), respectively, when administered in combination. Arsenic exposure led to the inhibition of blood delta-aminolevulinic acid dehydratase (ALAD) activity and depletion of glutathione (GSH) level. These changes were accompanied by significant depletion of hemoglobin, RBC and Hct as well as blood superoxide dismutase (SOD) acitivity. There was an increase in hepatic and renal levels of thiobarbituric acid-reactive substances, while GSH:GSSG ratio decreased significantly, accompanied by a significant increase in metallothionein (MT) in hepatocytes. DNA damage based on denaturing polyacrylamide gel electrophoresis revealed significant loss in the integrity of DNA extracted from the liver of arsenic-exposed rats compared to that of normal animals. These changes were accompanied by a significant elevation in blood and soft-tissue arsenic concentration. Co-administration of DMSA and MiADMSA at lower dose (0.15 mmol/kg) was most effective not only in reducing arsenic-induced oxidative stress but also in depleting arsenic from blood and soft tissues compared to other treatments. This combination was also able to repair DNA damage caused following arsenic exposure. We thus recommend combined administration of DMSA and MiADMSA for achieving optimum effects of chelation therapy.",
Arsenic,1031977,"Isolation and immunological characterization of the mammalian 32-/34-kDa stress protein Abstract: Challenge of mammalian cells with heavy metals or sulfhydryl-reactive agents including sodium arsenite induces the de novo synthesis of a 32-/34-kDa stress protein (p32) (M. M. Caltabiano, T. P. Koestler, G. Poste, and R. G. Greig (1986) J. Biol. Chem. 261, 13,381). Here we report that antibody prepared against p32/p34 purified from human A375 melanoma cells immunoprecipitated an antigen of similar molecular mass from a panel of human, rat, and murine cells following challenge with sodium arsenite. No reactivity was observed in lysates from control, uninsulted cultures. The precise molecular mass of the arsenite-induced antigen was species-specific: 32 kDa (human and rat) and 34 kDa (murine). Indirect immunofluorescence analysis using affinity-purified monospecific IgG demonstrated that p32/p34 was localized to the cytoplasm and displayed a perinuclear distribution.",
Arsenic,1029620,"Characterizing arsenic in preserved hair for assessing exposure potential and discriminating poisoning Abstract: Advanced analytical techniques have been used to characterize arsenic in taxidermy specimens. Arsenic was examined to aid in discriminating its use as a preservative from that incorporated by ingestion and hence indicate poisoning (in the case of historical figures). The results are relevant to museum curators, occupational and environmental exposure concerns, toxicological and anthropological investigations. Hair samples were obtained from six taxidermy specimens preserved with arsenic in the late 1800s and early 1900s to investigate the arsenic incorporation. The presence of arsenic poses a potential hazard in museum and private collections. For one sample, arsenic was confirmed to be present on the hair with time-of-flight secondary ion mass spectrometry and then measured with neutron activation analysis to comprise 176 microg g(-1). The hair cross section was analysed with synchrotron micro-X-ray fluorescence to investigate the transverse distribution of topically applied arsenic. It was found that the arsenic had significantly penetrated all hair samples. Association with melanin clusters and the medulla was observed. Lead and mercury were also identified in one sample. X-ray absorption near-edge spectroscopy of the As K-edge indicated that an arsenate species predominantly existed in all samples; however, analysis was hindered by very rapid photoreduction of the arsenic. It would be difficult to discriminate arsenic consumption from topically applied arsenic based on the physical transverse distribution. Longitudinal distributions and chemical speciation may still allow differentiation.",
Arsenic,1070461,"Arsenic promotes ubiquitinylation and lysosomal degradation of cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels in human airway epithelial cells Abstract: Arsenic exposure significantly increases respiratory bacterial infections and reduces the ability of the innate immune system to eliminate bacterial infections. Recently, we observed in the gill of killifish, an environmental model organism, that arsenic exposure induced the ubiquitinylation and degradation of CFTR, a chloride channel that is essential for the mucociliary clearance of respiratory pathogens in humans. Accordingly, in this study we tested the hypothesis that low dose arsenic exposure reduces the abundance and function of CFTR in human airway epithelial cells. Arsenic induced a time and dose-dependent increase in multi-ubiquitinylated CFTR, which led to its lysosomal degradation, and a decrease in CFTR mediated chloride secretion. Although arsenic had no effect on the abundance or activity of USP10, a deubiquitinylating enzyme, siRNA-mediated knockdown of c-Cbl, an E3-ubiquitin ligase, abolished the arsenic-stimulated degradation of CFTR. Arsenic enhanced the degradation of CFTR by increasing phosphorylated c-Cbl, which increased its interaction with CFTR, and subsequent ubiquitinylation of CFTR. Because epidemiological studies have shown that arsenic increases the incidence of respiratory infections, this study suggests that one mechanism of this effect involves arsenic induced ubiqutinylation and degradation of CFTR, which decreases chloride secretion and airway surface liquid volume, effects that are proposed to reduce mucociliary clearance of respiratory pathogens.",
Arsenic,627658,"Acquisition of androgen independence by human prostate epithelial cells during arsenic-induced malignant transformation Abstract: Lethal phenotypes of human prostate cancer are characterized by progression to androgen independence, although the mechanisms behind this progression remain unclear. Arsenic is a potential human prostate carcinogen that may affect tumor progression. In this study, we used a prostate cancer cell model in which an immortalized, nontumorigenic human prostate epithelial cell line (RWPE-1) had been malignantly transformed by chronic low-level arsenic to help determine whether arsenic affects prostate tumor progression. Control and CAsE-PE (chronic-arsenic-exposed human prostate epithelial) cells were continuously maintained in a complete medium [keratinocyte serum-free medium (K-SFM) with bovine pituitary extract and epidermal growth factor] or in a steroid-depleted medium (K-SFM alone). The arsenic-transformed cells showed a more rapid proliferation rate in complete medium than did control cells and also showed sustained proliferation in steroid-reduced medium. Although both control and CAsE-PE cells showed similar levels of androgen receptor (AR), androgens were less effective in stimulating cell proliferation and AR-related gene expression in CAsE-PE cells. For instance, dihydrotestosterone caused a 4.5-fold increase in prostate-specific antigen transcript in control cells but only a 1.5-fold increase in CAsE-PE cells. CAsE-PE cells also showed relatively low levels of growth stimulation by nonandrogen steroids, such as estradiol. Thus, arsenic-induced malignant transformation is associated with acquired androgen independence in human prostate cells. This acquired androgen independence was apparently not due to AR up-regulation, increased activity, or altered ligand specificity. The precise manner in which arsenic altered CAsE-PE growth and progression is undefined but may involve a bypass of AR involving direct stimulation of downstream signaling pathways.",
Arsenic,628822,"Arsenic induces apoptosis of multidrug-resistant human myeloid leukemia cells that express Bcr-Abl or overexpress MDR, MRP, Bcl-2, or Bcl-x(L) Abstract: We investigated the in vitro growth inhibitory and apoptotic effects of clinically achievable concentrations of As(2)O(3) (0.5 to 2.0 micromol/L) against human myeloid leukemia cells known to be resistant to a number of apoptotic stimuli. These included chronic myelocytic leukemia (CML) blast crisis K562 and HL-60/Bcr-Abl cells, which contain p210 and p185 Bcr-Abl, respectively, and HL-60 cell types that overexpress Bcl-2 (HL-60/Bcl-2), Bcl-x(L) (HL-60/Bcl-x(L)), MDR (HL-60/VCR), or MRP (HL-60/AR) protein. The growth-inhibitory IC(50) values for As(2)O(3) treatment for 7 days against all these cell types ranged from 0.8 to 1.5 micromol/L. Exposure to 2 micromol/L As(2)O(3) for 7 days induced apoptosis of all cell types, including HL-60/Bcr-Abl and K562 cells. This was associated with the cytosolic accumulation of cyt c and preapoptotic mitochondrial events, such as the loss of inner membrane potential (DeltaPsim) and the increase in reactive oxygen species (ROS). Treatment with As(2)O(3) (2 micromol/L) generated the activities of caspases, which produced the cleavage of the BH3 domain containing proapoptotic Bid protein and poly (ADP-ribose) polymerase. Significantly, As(2)O(3)-induced apoptosis of HL-60/Bcr-Abl and K562 cells was associated with a decline in Bcr-Abl protein levels, without any significant alterations in the levels of Bcl-x(L), Bax, Apaf-1, Fas, and FasL. Although As(2)O(3 )treatment caused a marked increase in the expression of the myeloid differentiation marker CD11b, it did not affect Hb levels in HL-60/Bcr-Abl, K562, or HL-60/neo cells. However, in these cells, As(2)O(3 )potently induced hyper-acetylation of the histones H3 and H4. These findings characterize As(2)O(3) as a growth inhibiting and apoptosis-inducing agent against a variety of myeloid leukemia cells resistant to multiple apoptotic stimuli.",
Arsenic,1339730,"DEF6, a novel substrate for the Tec kinase ITK, contains a glutamine-rich aggregation-prone region and forms cytoplasmic granules that co-localize with P-bodies Abstract: Localization of DEF6 (SLAT/IBP), a Rho-family guanine nucleotide exchange factor, to the center of the immune synapse is dependent upon ITK, a Tec-family kinase that regulates the spatiotemporal organization of components of T cell signaling pathways and Cdc42-dependent actin polymerization. Here we demonstrate that ITK both interacts with DEF6 and phosphorylates DEF6 at tyrosine residues Tyr(210) and Tyr(222). Expression of a GFP-tagged Y210E-Y222E phosphomimic resulted in the formation of DEF6 cytoplasmic granules that co-localized with decapping enzyme 1 (DCP1), a marker of P-bodies; sites of mRNA degradation. Similarly treatment of cells with puromycin or sodium arsenite, reagents that arrest translation, also resulted in the accumulation of DEF6 in cytoplasmic granules. Bioinformatics analysis identified a glutamine-rich, heptad-repeat region; a feature of aggregating proteins, within the C-terminal region of DEF6 with the potential to promote granule formation through a phosphorylation-dependent unmasking of this region. These data suggest that in addition to its role as a GEF, DEF6 may also function in regulating mRNA translation.",
Arsenic,1018441,"Effects of acute and chronic arsenic exposure of human-derived keratinocytes in an In Vitro human skin equivalent system: a novel model of human arsenicism Abstract: An organotypic culture (OTC) of a human keratinocyte cell line (HaCaT) over a human fibroblast-embedded collagen gel was used to model human epidermis in arsenicism, a syndrome that currently lacks valid experimental models. Keratinocytes were exposed acutely or chronically to a mixture of arsenate (0.5 muM), monomethylarsonic acid (MMA; 0.5 muM) and dimethylarsinic acid (DMA; 1.5 muM), or to the individual components of the mixture. OTCs were assayed for microscopic morphology, the proliferating cell marker, Ki-67, labelling and cytokeratin expression. Acute exposures resulted in an epidermal phenotype that accurately modelled early human lesions, including hyperkeratosis, acanthosis and keratin 16 induction. Chronic exposures resulted in a de-differentiated epidermal phenotype with focal nests of keratinocytes growing into the collagen gel. The keratin 8 18 pair was induced by either acute or chronic arsenic exposure, as was the proliferating cell marker, Ki-67. Exposure of keratinocytes to individual arsenic compounds demonstrated that all arsenic mixture-induced changes could be duplicated by exposure to arsenate alone. In contrast, MMA and DMA were inactive. This study establishes OTC as a useful model of arsenicism, and implicates inorganic arsenic as the ultimate carcinogen.",
Arsenic,61491,"Arsenic in drinking water and mortality from vascular disease: An ecologic analysis in 30 counties in the United States Abstract: Chronic arsenic consumption can cause vascular diseases. Adverse vascular effects of arsenic in drinking water in the United States have not been studied. This study investigated the ecological relationship between the population-weighted mean arsenic concentration in public drinking water supplies and mortality from circulatory diseases in 30 U.S. counties from 1968 to 1984. Mean arsenic levels ranged from 5.4 to 91.5 micrograms/l. Standardized mortality ratios (SMRs) for diseases of arteries, arterioles, and capillaries (DAAC) (ICD 8th/9th revision, 440-448) for counties exceeding 20 micrograms/l were 1.9 (90% confidence interval [CI] = 1.7-2.1) for females and 1.6 (90% CI = 1.5-1.8) for males. The SMRs for the three subgroups of DAAC--arteriosclerosis, aortic aneurysm, and all other DAAC--tended to be elevated. With respect to the same arsenic group, the SMRs for congenital anomalies of the heart (ICD-8/9, 746/745-746) and circulatory system (ICD-8/9, 747) also tended to be elevated. Two competing interpretations emerge as possibilities: either there are spurious associations resulting from invalid outcome data or causal associations.",
Arsenic,1034311,"Arsenic levels in blood, urine, and hair of workers applying monosodium methanearsonate (MSMA) Abstract: Uptake and excretion of total arsenic from monosodium methanearsonate (MSMA) in workers who applied the herbicide was followed during the spraying season. Urine, blood, and hair samples were collected and air samples were taken from the workers' breathing zone. Arsenic concentrations in air samples ranged from 0.001-1.086 micrograms/m3. Blood and urine arsenic values ranged from 0.0-0.2 mg/L and 0.002-1.725 mg/L, respectively. The geometric mean arsenic concentration in urine increased during the week but returned to base levels on weekends. Hair arsenic concentrations ranged from 0.02-358.0 mg/kg, increased during the spraying season, and returned to pre-season levels once herbicide application ceased. Three workers had higher than normal pre-exposure hair values. However, only one of the three workers had consistently above normal values throughout the study period.",
Arsenic,1356869,"Examining biomarkers of exposure and preparation techniques for arsenic quantitation In biological studies Abstract: Accurate quantitation of any contaminant of interest is critical for toxicity and metabolism studies that support risk assessment. A first step in an arsenic exposure assessment study in Nevada quantified total arsenic (TAs) concentrations in biomarkers of exposure. Participants in this IRB approved study (N=95) were at least 45 years old, had lived in the area for more than 20 years, and were exposed to a wide range of arsenic concentrations in drinking water (3 ppb to 2100 ppb). Concentrations of arsenic in drinking water were determined for each subject by graphite furnace-atomic absorption spectrometry. Concentrations of TAs in urine, blood, and toenails were determined by hydride generation-atomic fluorescence spectrometry (HGAFS); toenail TAs was also determined by neutron activation analysis (NAA). TAs concentrations in blood, urine, and toe nail samples ranged from below HGAFS detection to 0.03 ppm, 0.76 ppm, and 12 ppm, respectively. TAs in blood rarely exceeded the limit of detection. A good correlation was found between the TAs concentration in nails and in drinking water (r2=0.46, p<0.001); a poorer correlation was found between TAs concentrations in urine and drinking water (r2=0.19, p<0.001). Analyses of TAs in toenails by HGAFS and NAA yielded highly concordant estimates (r2=0.84, p<0.001). These results suggest that toenails are a better biomarker of exposure than urine because the sequestration of As in toenails provides an integration of exposure over time that does not occur in urine.",
Arsenic,1337544,"Application of natural citric acid sources and their role on arsenic removal from drinking water: A green chemistry approach Abstract: Solar Oxidation and Removal of Arsenic (SORAS) is a low-cost non-hazardous technique for the removal of arsenic (As) from groundwater. In this study, we tested the efficiency of natural citric acid sources extracted from tomato, lemon and lime to promote SORAS for As removal at the household level. The experiment was conducted in the laboratory using both synthetic solutions and natural groundwater samples collected from As-polluted areas in West Bengal. The role of As/Fe molar ratios and citrate doses on As removal efficiency were checked in synthetic samples. The results demonstrate that tomato juice (as citric acid) was more efficient to remove As from both synthetic (percentage of removal: 78-98%) and natural groundwater (90-97%) samples compared to lemon (61-83% and 79-85%, respectively) and lime (39-69% and 63-70%, respectively) juices. The As/Fe molar ratio and the citrate dose showed an 'optimized central tendency' on As removal. Anti-oxidants, e.g. 'hydroxycinnamates', found in tomato, were shown to have a higher capacity to catalyze SORAS photochemical reactions compared to 'flavanones' found in lemon or lime. The application of this method has several advantages, such as eco- and user- friendliness and affordability at the household level compared to other low-cost techniques.",
Arsenic,656694,"Prevalence of arsenic-related skin lesions in 53 widely-scattered villages of Bangladesh: An ecological survey Abstract: A survey was carried out to provide a representative assessment of prevalence and risk of arsenic-related skin lesions in relation to geographical distribution of arsenic in wells of rural Bangladesh as a necessary background for research into effects in pregnancy and cancer risks. A systematic random sample of 53 villages in four divisions of Bangladesh served by Gonoshasthaya Kendra was selected, and all women aged 18 years or more (n=16,740) were listed. Trained paramedics recorded the presence of skin thickening and nodules on the palms and soles, together with information on tubewell use. The prevalence was related to the mean concentration of arsenic for the district as indicated by data from the British Geological Survey and to the date the first well in the village was installed. Overall, the observed prevalence was 176 cases (1.3%) in 13,705 women examined, varying from 0% in 26 villages to 23% in one; lesions were observed more frequently on hands than on feet. The estimate doubled with concentrations of arsenic from 11 to < or =50 microg/L and increased more than 20 times at >50 microg/L. In the absence of further information, priority for control measures should be directed at areas where the average concentrations of arsenic are above 50 microg/L, especially in villages where skin lesions have been identified.",
Arsenic,1579396,Speciation of Organoarsenic Species in Food of Animal Origin Using Accelerated Solvent Extraction (ASE) with Determination by HPLC-Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) Abstract: ,
Arsenic,1346550,"Development of a dairy cattle drinking water quality index (DCWQI) based on fuzzy inference systems Abstract: The critical role of water quality for all animals, and especially dairy cattle, the dairy products of which are consumed by humans, raises the need for an index which represents well the quality of water consumed by dairy cattle. Noting the high subjectivity and inappropriate classifications that traditional methods apply to development an index, we aimed to develop a better index that measures the quality of drinking water supplied to dairy cattle (DCWQI1) based on fuzzy logic. Using fuzzy logic enabled us to capture experts’ knowledge and to simulate the human's way of thinking in the design of the index. Our approach avoided the shortcomings of the previous models. We selected 20 parameters that available literature determined were critical to assessing the quality of water for dairy cattle to drink due mainly to their potential impacts both on dairy cattle and human health. These parameters were: dissolved oxygen (DO), biochemical oxygen demand (BOD), pH, temperature, total dissolved solids (TDS), turbidity, fecal coliform, heterotrophic plate count, hardness, alkalinity, arsenic, lead, mercury, nickel, cadmium, chromium, total phosphorous, H2S, nitrate, and fluoride. We used trapezoidal membership functions and the final ruleset consisted of 550 rules. Mamdani inference system captured experts’ knowledge and experience; center-of-gravity method was used to defuzzify the results. To evaluate the index performance, we conducted a case study of Karun River employing the water quality data from six sampling stations along the river over the period of 2007–2010 and compared the results to those from the National Sanitation Foundation (NSF) water quality index (WQI). Our study found that the water quality of Karun River lies in the low to medium range (annual mean index values of 38–55). In addition, the values from the fuzzy DCWQI were generally lower than the values from the NSF WQI, mainly because the DCWQI included heavy metals in its index, while the NSF WQI did not. Results of the present study suggest that DCWQI can be considered as a comprehensive tool for assessing the quality of water for dairy cattle drinking purposes and can be reliably used for that objective.",
Arsenic,1346553,"Simultaneous determination of arsenic(III) and arsenic(V) in atmospheric particulate matter by electrically heated quartz hydride-generation atomic absorption spectrometry Abstract: A method based on hydride generation atomic absorption spectrometry (HG-AAS) using an electrically heated quartz tube was developed for simultaneous determination of As(III) and As(V) associated with total suspended particles (TSP) and PM10 particles collected from urban and rural atmosphere. The concentrations of As(III) and As(V) associated with total suspended particles and PM10 were simultaneously determined. The monthly variation in atmospheric concentrations of As(III) and As(V) was investigated and indicated that the higher concentrations were found in December, January and February, respectively. The atmospheric concentration of total arsenic was also determined in rural and urban areas and the results showed the lower atmospheric concentrations in rural area with lower traffic density. An excellent co-variation in concentrations of arsenic, PM10 and CO indicated that arsenic is mostly released into the atmosphere from anthropogenic sources and especially from combustion of fossil fuels in automobile engines.",
Arsenic,1340080,"Abundance and diversity of ammonia-oxidizing prokaryotes in the root-rhizosphere complex of Miscanthus × giganteus grown in heavy metal-contaminated soils Abstract: Mine wastes have been considered as a source of heavy metal (HM) contamination in the environment and negatively impact many important ecosystem services provided by soils. Plants like Miscanthus, which tolerate high HM concentrations in soil, are often used for phytoremediation and provide the possibility to use these soils at least for the production of energy crops. However, it is not clear if plant growth at these sites is limited by the availability of nutrients, mainly nitrogen, as microbes in soil might be affected by the contaminant. Therefore, in this study, we investigated in a greenhouse experiment the response of ammonia-oxidizing microbes in the root-rhizosphere complex of Miscanthus × giganteus grown in soils with different levels of long-term arsenic (As) and lead (Pb) contamination. Quantitative PCR of the ammonia monooxigenease gene (amoA) was performed to assess the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) at two different points of plant growth. Furthermore, bulk soil samples before planting were analyzed. In addition, terminal restriction fragment length polymorphism (T-RFLP) analysis was used to investigate the diversity of archaeal amoA amplicons. Whereas high concentrations of As and Pb in soil (83 and 15 g/kg, respectively) resulted independent from plant growth in a clear reduction of AOA and AOB compared to the control soils with lower HM contents, in soils with contamination levels of 10 g/kg As and 0.2 g/kg Pb, only AOB were negatively affected in bulk soil samples. Diversity analysis of archaeal amoA genes revealed clear differences in T-RFLP patterns in response to the degree of HM contamination. Therefore, our results could clearly prove the different response patterns of AOA and AOB in HM-contaminated soils and the development of archaeal amoA phylotypes which are more tolerant towards HMs in soil samples from the areas that were impacted the most by mining waste, which could contribute to functional redundancy of ammonia-oxidizing microbes in soils and stability of nitrification pattern.",
Arsenic,627156,"Low dose arsenic compromises the immune response to influenza A infection in vivo Abstract: Arsenic exposure is a significant worldwide environmental health concern. We recently reported that 5-week exposure to environmentally relevant levels (10 and 100 ppb) of As in drinking water significantly altered components of the innate immune response in mouse lung, which we hypothesize is an important contributor to the increased risk of lung disease in exposed human populations.<br /><br /> We investigated the effects of As exposure on respiratory influenza A (H1N1) virus infection, a common and potentially fatal disease.<br /><br /> In this study, we exposed C57BL/6J mice to 100 ppb As in drinking water for 5 weeks, followed by intranasal inoculation with a sub lethal dose of influenza A/PuertoRico/8/34 (H1N1) virus. Multiple end points were assessed postinfection.<br /><br /> Arsenic was associated with a number of significant changes in response to influenza, including an increase in morbidity and higher pulmonary influenza virus titers on day 7 post-infection. We also found many alterations in the immune response relative to As-unexposed controls, including a decrease in the number of dendritic cells in the mediastinal lymph nodes early in the course of infection.<br /><br /> Our data indicate that chronic As exposure significantly compromises the immune response to infection. Alterations in response to repeated lung infection may also contribute to other chronic illnesses, such as bronchiectasis, which is elevated by As exposure in epidemiology studies.",
Arsenic,1034424,"Hemodialysis of acute arsenic intoxication with transient renal failure Abstract: A striking reduction in serum arsenic level was achieved after four hours of hemodialysis in a patient with acute arsenic intoxication and transient renal failure. Quantitative dialysance of arsenic and a comparison of daily urinary excretion of arsenic with amount removed by dialysis suggested that hemodialysis is indicated in the treatment of acute arsenic intoxication if there is concomitant renal failure. In the presence of normal renal function, supportive measures, including dimercaprol (BAL in Oil) therapy, constitute the best available treatment.",
Arsenic,628631,"Vascular dysfunction in patients with chronic arsenosis can be reversed by reduction of arsenic exposure Abstract: Chronic arsenic exposure causes vascular diseases associated with systematic dysfunction of endogenous nitric oxide. Replacement of heavily arsenic-contaminated drinking water with low-arsenic water is a potential intervention strategy for arsenosis, although the reversibility of arsenic intoxication has not established. In the present study, we examined urinary excretion of cyclic guanosine 3 ,5 -monophosphate (cGMP), a second messenger of the vasoactive effects of nitric oxide, and signs and symptoms for peripheral vascular function in 54 arsenosis patients before and after they were supplied with low-arsenic drinking water in an endemic area of chronic arsenic poisoning in Inner Mongolia, China. The arsenosis patients showed a marked decrease in urinary excretion of cGMP (mean +/- SEM: male, 37.0 +/- 6.1; female, 37.2 +/- 5.4 nmol/mmol creatinine), and a 13-month period of consuming low-arsenic drinking water reversed this trend (male, 68.0 +/- 5.6; female, 70.6 +/- 3.0 nmol/mmol creatinine) and improved peripheral vascular response to cold stress. Our intervention study indicates that peripheral vascular disease in arsenosis patients can be reversed by exposure cessation and has important implications for the public health approach to arsenic exposure.",
Arsenic,1597388,Determination of Arsenic in Panax notoginseng by Hydride Generation Atomic Fluorescence Spectrometry Abstract: ,
Arsenic,2149094,"Formation of two-dimensionally confined superparamagnetic (Mn, Ga)As nanocrystals in high-temperature annealed (Ga, Mn)As/GaAs superlattices Abstract: The annealing-induced formation of (Mn, Ga)As nanocrystals in (Ga, Mn)As/GaAs superlattices was studied by x-ray diffraction, transmission electron microscopy and magnetometry. The superlattice structures with 50 ? thick (Ga, Mn)As layers separated by 25, 50 and 100 ? thick GaAs spacers were grown by molecular beam epitaxy at low temperature (250 °C), and then annealed at high temperatures of 400, 560 and 630 °C. The high-temperature annealing causes decomposition to a (Ga, Mn)As ternary alloy and the formation of (Mn, Ga)As nanocrystals inside the GaAs matrix. The nanocrystals are confined in the planes that were formerly occupied by (Ga, Mn)As layers for the up to 560 °C annealing and diffuse throughout the GaAs spacer layers at 630 °C annealing. The two-dimensionally confined nanocrystals exhibit a superparamagnetic behavior which becomes high-temperature ferromagnetism (~350 K) upon diffusion.",
Arsenic,628005,"Arsenic mediates cell proliferation and gene expression in the bladder epithelium: association with activating protein-1 transactivation Abstract: Although the mechanism of action has not yet been defined, epidemiological studies have demonstrated an association between elevated arsenic levels in drinking water and the incidence of urinary bladder transitional cell carcinomas. In the current studies, we demonstrate that mice exposed to 0.01% sodium arsenite in drinking water develop hyperplasia of the bladder urothelium within 4 weeks of exposure. This was accompanied by the accumulation of inorganic trivalent arsenic, and to a lesser extent dimethylarsinic acid, in bladder tissue, as well as a persistent increase in DNA binding of the activating protein (AP)-1 transcription factor. AP-1 transactivation by arsenic also occurred in bladders of transgenic mice containing an AP-1 luciferase reporter. Consistent with these in vivo observations, arsenite increased cell proliferation and AP-1 DNA binding in a human bladder epithelial cell line. Gene expression studies using RNase protection assays, reverse transcription-PCR, and cDNA microarrays indicated that arsenite alters the expression of a number of genes associated with cell growth, such as c-fos, c-jun, and EGR-1, as well as cell arrest, such as GADD153 and GADD45. The proliferation-enhancing effect of arsenic on uroepithelial cells likely contributes to its ability to cause cancer.",
Arsenic,628720,"Ingested arsenic and internal cancer: A historical cohort study followed for 33 years Abstract: A historical cohort study was conducted to investigate the long-term effect of exposure to ingested arsenic. The 454 residents who had been identified in a list made in 1959 were followed until 1992. They lived in an arsenic-polluted area, called Namiki-cho, Nakajo-machi, in Niigata Prefecture, Japan, and used well water containing inorganic arsenic. The exposure period was estimated to be about 5 years (1955–1959). Death certificates for the people who died between 1959 and 1992 were examined, and a total of 113 of the 454 residents were estimated to have drunk well water containing a high dose of arsenic (?1 ppm). The standardized mortality rate ratios of these 113 residents were 15.69 for lung cancer (observed/expected = 8/0.51; 95% confidence interval (CI) 7.38–31.02) and 31.18 for urinary tract cancer (observed/expected = 3/0.10; 95% CI 8.62–91.75). Cox's proportional hazard analyses demonstrated that the hazard ratios of the highest exposure level group (?1 ppm) versus the background exposure level group (0.001 ppm) were 1.74 (95% CI 1.10–2.74) for all deaths and 4.82 (95% CI 2.09–11.14) for all cancers. The analysis according to the skin signs of chronic arsenicism in 1959 showed that they were useful risk indicators for subsequent cancer development. In the development of lung cancer, there was evidence of synergism between arsenic intake and smoking habit.",
Arsenic,1936166,"Arsenate adsorption by unsaturated alluvial sediments Abstract: Arsenic can occur naturally in excess of drinking water standards. Earlier a field-scale recharge pond experiment in the Antelope Valley ground water basin, Mohave Desert, California, was performed to determine the effectiveness of naturally occurring minerals in the unsaturated zone to treat high As water. The extent to which the remediation can be continued on any site is unknown and depends on the As adsorption properties and capacity of the sediments. Therefore, arsenate adsorption reactions as a function of solution As concentration and solution pH were investigated on five alluvial sediments obtained from various depths of a borehole adjacent to the recharge pond. Arsenate adsorption increased with increasing solution pH, exhibited a maximum around pH 4 to 5, and then decreased with increasing pH. The constant capacitance model was able to fit arsenate adsorption on the sediments as a function of solution As concentration and solution pH. A general regression model was used to predict arsenate surface complexation constants from routinely measured chemical parameters. The predicted arsenate constants were used to predict adsorption on the sediments, thereby providing a completely independent evaluation of the ability of the model to describe arsenate adsorption. The prediction equations were able to satisfactorily predict arsenate adsorption on one of the five sediments whose chemical properties fell into the range for the set of soils used to develop the prediction equations. Equimolar phosphate concentrations did not affect the extent of arsenate adsorption indicating that the extent of arsenate remediation by the sediments will be unaffected by the low amounts of native phosphate.",
Arsenic,2343449,"Sarcomatoid dedifferentiation in metastatic clear cell renal cell carcinoma and outcome on treatment with anti-vascular endothelial growth factor receptor tyrosine kinase inhibitors: A retrospective analysis Abstract: <strong>INTRODUCTION: </strong>This study aimed to assess the efficacy of anti-vascular endothelial growth factor receptor tyrosine kinase inhibitors (anti-VEGFR-TKIs) in patients with metastatic clear cell renal cell carcinoma (m-ccRCC) with sarcomatoid dedifferentiation.<br /><br /><strong>PATIENTS AND METHODS: </strong>The files of all patients with m-ccRCC consecutively treated with first-line anti-VEGFR-TKIs at the authors' institution were retrospectively reviewed. Pathology slides from nephrectomy and metastasectomy were assessed for the presence and extent of sarcomatoid dedifferentiation.<br /><br /><strong>RESULTS: </strong>A total of 124 patients were included; nephrectomy and metastasectomy specimens were available in 117 and 35 patients, respectively. Thirty percent of the primary nephrectomy specimens had sarcomatoid features, and the median involvement of the sarcomatoid component was 21% (range, 1%-95%). Patients with an important sarcomatoid component, defined as ? 25% involvement of the tumor, had a very poor outcome: progression-free survival (PFS) and overall survival (OS) were 3 and 6 months, respectively, and no partial responses (PR) were observed. Patients without sarcomatoid dedifferentiation or with sarcomatoid involvement &lt; 25% had a PFS of 12 months (P &lt; .0001; hazard ratio [HR], 51; 95% CI, 12.58-207.3), an OS of 22 months (P &lt; .0001, HR, 10.72; 95% CI, 3.56-32.25), and a PR rate of 50% (P = .0015). Patients with a sarcomatoid component ? 25% in the metastasectomy also had a poorer PFS and OS on anti-VEGFR-TKIs compared with patients with &lt; 25% of sarcomatoid features at these sites.<br /><br /><strong>CONCLUSION: </strong>Patients with m-ccRCC whose tumors contain a component of sarcomatoid dedifferentiation of ? 25% of the total tumor volume have a very poor outcome when treated with anti-VEGFR-TKIs. Analysis of the extent of sarcomatoid features in resected metastases can provide additional prognostic information.",
Arsenic,1339105,"Arsenite-induced autophagy is associated with proteotoxicity in human lymphoblastoid cells Abstract: Epidemiological studies of arsenic-exposed populations have provided evidence that arsenic exposure in humans is associated with immunosuppression. Previously, we have reported that arsenite-induced toxicity is associated with the induction of autophagy in human lymphoblastoid cell lines (LCL). Autophagy is a cellular process that functions in the degradation of damaged cellular components, including protein aggregates formed by misfolded or damaged proteins. Accumulation of misfolded or damaged proteins in the endoplasmic reticulum (ER) lumen causes ER stress and activates the unfolded protein response (UPR). In an effort to investigate the mechanism of autophagy induction by arsenite in the LCL model, we examined the potential contribution of ER stress and activation of the UPR. LCL exposed to sodium arsenite for 8-days induced expression of UPR-activated genes, including CHOP and GRP78, at the RNA and the protein level. Evidence for activation of the three arms of the UPR was observed. The arsenite-induced activation of the UPR was associated with an accumulation of protein aggregates containing p62 and LC3, proteins with established roles in the sequestration and autophagic clearance of protein aggregates. Taken together, these data provide evidence that arsenite-induced autophagy is associated with the generation of ER stress, activation of the UPR, and formation of protein aggregates that may be targeted to the lysosome for degradation.",
Arsenic,628372,"Intake of inorganic arsenic in the North American diet Abstract: Dietary intake of inorganic arsenic, previously assumed to be an insignificant source of arsenic exposure in humans, was estimated for Canadian and United States populations. Input data included arsenic contents of various food groups, a limited historical database from the Ontario Ministry of the Environment measuring the percent inorganic arsenic in food groups, and food consumption data. Estimated daily dietary intake of inorganic arsenic ranges from 8.3 to 14 µg/day in the United States and from 4.8 to 12.7 µg/day in Canada for various age groups. These data suggest that between 21% to 40% of total dietary arsenic occurs in inorganic forms. Uncertainties regarding total arsenic in dairy products in the data set applied here may account for observed differences between United States and Canadian estimates. While estimates provided here are preliminary because of limitations in data on the proportion of inorganic arsenic in foods, this analysis suggests that dietary intake of inorganic arsenic is higher than is currently assumed. Additional research is needed to more fully characterize inorganic arsenic concentrations in foods. Future study is also needed on the variability of total and inorganic arsenic in foods and the bioavailability of dietary inorganic arsenic.",
Arsenic,627507,"Plasma-transforming growth factor-alpha expression in residents of an arseniasis area in Taiwan Abstract: Epidemiological studies have demonstrated an association between long-term exposure to inorganic arsenic and the related adverse effects such as cancers, skin lesions, and vascular diseases. Although several hypotheses have been proposed for the mechanism of arsenic-induced pathogenesis, it remains imperfectly understood. Recent studies have suggested that alterations in growth signal transduction pathways, particularly involving transforming growth factor-alpha (TGF-alpha), may be important. Immunoassays were used to determine the plasma levels of TGF-alpha and epidermal growth factor receptor (EGFR), which is the receptor for TGF-alpha, in residents of an arseniasis area of Taiwan in relation to their estimated cumulative arsenic exposure from drinking water. No relationship between arsenic exposure and EGFR was found. However, among the high cumulative exposure group (>6 ppm-years), levels of plasma TGF-alpha (25.5+/-38.2 pg ml-1) and the proportion of individuals with TGF-alpha over-expression (29.4%) were significantly higher (p<0.05) than normal, healthy unexposed controls (8.1+/-5.6 pg ml-1, 8.6%, respectively). There was a significant linear trend between cumulative arsenic exposure and the prevalence of plasma TGF-alpha over-expression after adjusting for age and sex (p=0.019). The results suggest that plasma TGF-alpha expression may be a useful biomarker when detecting adverse effects on arsenic exposed population.",
Arsenic,1032227,"Glutathione S-transferase pi facilitates the excretion of arsenic from arsenic-resistant Chinese hamster ovary cells Abstract: We have previously demonstrated that glutathione S-transferase pi (GST pi) is overexpressed in SA7 cells, an arsenic resistant cell line derived from Chinese hamster ovary (CHO) cells. Our present results show that SA7 cells accumulate less arsenic than parental CHO cells and partially revertant SA7N cells. The lower levels of arsenic accumulation in SA7 cells resulted from their faster excretion rates. However, the excretion of arsenic from SA7 cells was significantly inhibited by the GST inhibitors ethacrynic acid and Cibacron blue. Furthermore, when GST pi levels in SA7N cells were re-elevated by zinc sulfate pretreatment, arsenic accumulation decreased and arsenic excretion increased to levels similar to those in SA7 cells. These results suggest that GST pi can facilitate the excretion of arsenic. Such facilitation by GST pi is unlikely to be associated with multi-drug resistant P-glycoprotein, since no overexpression of P-glycoprotein was detected in SA7N and SA7 cells.",
Arsenic,1028594,"Spatial pattern of groundwater arsenic occurrence and association with bedrock geology in greater Augusta, Maine Abstract: In New England, groundwater arsenic occurrence has been linked to bedrock geology on regional scales. To ascertain and quantify this linkage at intermediate (10(0)-10(1) km) scales, 790 groundwater samples from fractured bedrock aquifers in the greater Augusta, Maine area are analyzed, and 31% of the sampled wells have arsenic concentrations &gt;10 microg/L. The probability of [As] exceeding 10 microg/L mapped by indicator kriging is highest in Silurian pelite-sandstone and pelite-limestone units (approximately 40%). This probability differs significantly (p &lt; 0.001) from those in the Silurian-Ordovician sandstone (24%),the Devonian granite (15%), and the Ordovician-Cambrian volcanic rocks (9%). The spatial pattern of groundwater arsenic distribution resembles the bedrock map. Thus, bedrock geology is associated with arsenic occurrence in fractured bedrock aquifers of the study area at intermediate scales relevant to water resources planning. The arsenic exceedance rate for each rock unit is considered robust because low, medium, and high arsenic occurrences in four cluster areas (3-20 km2) with a low sampling density of 1-6 wells per km2 are comparable to those with a greater density of 5-42 wells per km2. About 12,000 people (21% of the population) in the greater Augusta area (approximately 1135 km2) are at risk of exposure to &gt;10 microg/L arsenic in groundwater.",
Arsenic,2337076,"Dysfunction of Vascular Smooth Muscle and Vascular Remodeling by Simvastatin Abstract: Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, are widely prescribed for hypercholesterolemia. With the increasing use of statins, numerous reports demonstrated that statins can cause damage to skeletal muscles. However, the toxicities of statins on vascular smooth muscle, which are essential to cardiovascular homeostasis, have not been previously described. Here, we examined the effects of simvastatin on the contractile function and the integrity of vascular smooth muscle in isolated rat thoracic aortic rings, primary cultured vascular smooth muscle cells (VSMCs) in vitro and rats in vivo. In aortic rings, simvastatin suppressed the normal agonist-induced contractile responses in time- and concentration-dependent manners (0.86 g +/- 0.11 at 10 mu M simvastatin for 24 h compared with 1.89 g +/- 0.11 at control). The suppression persisted in the endothelium-denuded aortic rings and was irreversible even after wash-out of simvastatin. Simvastatin suppressed the contraction induced by Bay K8644, an activator of voltage-operated Ca2+ channel (VOCC) in rat aortic rings and abolished agonist-induced intracellular Ca2+ increase in VSMCs. The simvastatin-induced contractile dysfunction was reversed by the supplementation of mevalonate and geranylgeranylpyrophosphate, precursors for protein isoprenylation. Consistently, activation of RhoA, a representative isoprenylated protein, was disrupted by simvastatin in VSMCs and RhoA-mediated phosphorylation of MYPT1 and CPI-17, and tonic tension were also suppressed. Notably, prolonged treatment of simvastatin up to 48 h induced apoptosis of vascular smooth muscle in aortic rings. Most importantly, simvastatin treatment in vivo significantly attenuated the agonist-induced vasoconstriction in rats ex vivo and induced a decrease in luminal area of the vascular wall. Collectively, these results demonstrate that simvastatin can impair the normal vascular contractility by disturbing Ca2+ influx and RhoA activity, ultimately leading to apoptosis and structural remodeling.",
Arsenic,627345,"Health Effects of Arsenic Longitudinal Study (HEALS): Description of a multidisciplinary epidemiologic investigation Abstract: Health Effects of Arsenic Longitudinal Study (HEALS), a multidisciplinary and large prospective cohort study in Araihazar, Bangladesh, was established to evaluate the effects of full-dose range arsenic (As) exposure on various health outcomes, including premalignant and malignant skin tumors, total mortality, pregnancy outcomes, and children's cognitive development. In this paper, we provide descriptions of the study methods including study design, study population, data collection, response rates, and exposure and outcome assessments. We also present characteristics of the study participants including the distribution of exposure and the prevalence of skin lesion at baseline recruitment. A total of 11,746 married men and women between 18 and 75 years of age participated in the study at baseline (a response rate of 98%) and completed a full questionnaire interview that included a food frequency questionnaire, with a response rate of 98%. Among the 98% of the participants who completed the clinical evaluation, over 90% provided blood samples and spot urine samples. Higher educational status, male gender, and presence of premalignant skin lesions were associated with an increased likelihood of providing blood and urine samples. Older participants were less likely to donate a blood sample. About one-third of the participants consumed water from a well with As concentration in each of three groups: >100 microg/l, 25-100 microg/l, and <25 microg/l. Average urinary As concentrations were 140 and 136 microg/l for males and females, respectively. HEALS has several unique features, including a prospective study design, comprehensive assessments of both past and future changes in As exposure at the individual level, a large repository of biological samples, and a full dose range of As exposures in the study population. HEALS is a valuable resource for examining novel research questions on the health effects of As exposure.",
Arsenic,1508602,"Arsenic induced toxicity and histopathological changes in gill and liver tissue of freshwater fish, tilapia (Oreochromis mossambicus) Abstract: Acute toxicity of arsenic to tilapia (Oreochromis mossambicus) and its histopathological impacts on gill and liver tissue were evaluated. The median lethal concentration (96h; LC(50)) of arsenic (NaAsO(2)) was calculated as 28.22ppm in repeated semi static test method. Fish were exposed to 3ppm, 28ppm and 56ppm concentrations of NaAsO(2) and gill and liver samples were collected after 48h, 96h and 192h of exposure. The changes in gill were characterized by epithelial hyperplasia, epithelial lifting and oedema, lamellar fusion, aneurism, desquamation and necrosis, whereas, the liver tissue showed focal lymphocytic and macrophage infiltration, congestion, vacuolization and shrinkage of hepatocytes, dilation of sinusoids, cloudy swelling, vacuolar degeneration, focal necrosis and nuclear hypertrophy. The result showed that acute arsenic toxicity severely affects the normal behavior and vital organs which is deleterious for the exposed fish.",
Arsenic,2149363,"Biochemical view of uptake, metabolism and toxic effects of arsenic compounds on plants Abstract: Arsenic is a non-essential element in plant nutrition. However, As was detected in many agricultural plants, where it may pose a serious health hazard for next members of the food chain. This review presents the recent knowledge of As uptake, metabolism and transport in plants. Arsenates are taken up by phosphate transporters while arsenites are transported to cells via aquaporins located on cytoplasmic membranes. Inside the root cells, arsenates are rapidly reduced with arsenate reductase or some non-specific reducing agents. They are complexed by phytochelatins and then transported to vacuoles. Hyperaccumulators, instead of producing phytochelatins to detoxify As, transport free As to shoots and, similarly, accumulate it in vacuoles. The review highlights the importance of research on As phytotoxicity evaluation in terms of its impact on agricultural production. Exposure to As results in growth and reduction of biomass production, inhibition of germination, impaired nutrient uptake and adverse effects on photosynthetic processes. These aspects are discussed in the review.",
Arsenic,628093,"Arsenic ingestion and increased microvascular disease risk: Observations from the south-western arseniasis-endemic area in Taiwan Abstract: BACKGROUND: We established the association between arsenic ingestion and increased risk of vascular diseases associated with diabetes. However, the specific microvascular diseases in relation to arsenic exposure level have not been well reported. METHODS: The study population was obtained through national health database linkage. A total of 28 499 subjects living in the study area were successfully linked with their medical records from the National Health Insurance database in 1999-2000. The arsenic concentrations of artesian well water in the villages of the study area were utilized as indices of previous ingestion level. Both stratified analysis and unconditional logistic regression were used to examine mainly neurological and renal disease in relation to the arsenic exposure taking into account diabetes status. RESULTS: The age-adjusted and gender-adjusted prevalence of microvascular diseases was 7.51% [95% confidence interval (CI) 7.50-7.51] for arsenic level of <0.1 mg/litre, and then increased from 6.59% (6.59-6.60) for the arsenic concentrations of 0.1-0.29 mg/litre to 8.02% (8.02-8.03) and 11.82% (11.81-11.83) for those of 0.3-0.59 mg/litre and > or =0.6 mg/litre in non-diabetic subjects. For diabetic patients, the prevalence was 16.41% (95% CI 16.37-16.45), 15.85% (15.8-15.9), 21.69% (21.6-21.8), and 28.31% (28.2-28.4) for arsenic levels <0.1, 0.1-0.29, 0.3-0.59, and > or =0.6 mg/litre, respectively. The prevalence of microvascular diseases increased significantly with arsenic exposure, especially at higher levels, and the relationship is stronger in diabetics than in non-diabetic subjects. The results for neurological disease are very similar, and the patterns are the same for renal disease. CONCLUSIONS: The increased prevalence of microvascular diseases, including neurological and renal disorders, is associated with arsenic ingestion. This excess risk was further elevated in diabetic subjects. Further studies are necessary to verify the hypotheses of threshold or dose-response relationships.",
Arsenic,1337678,"A semi-mechanistic integrated toxicokinetic-toxicodynamic (TK/TD) model for arsenic(III) in hepatocytes Abstract: BACKGROUND: A systems engineering approach is presented for describing the kinetics and dynamics that are elicited upon arsenic exposure of human hepatocytes. The mathematical model proposed here tracks the cellular reaction network of inorganic and organic arsenic compounds present in the hepatocyte and analyzes the production of toxicologically potent by-products and the signaling they induce in hepatocytes. METHODS AND RESULTS: The present modeling effort integrates for the first time a cellular-level semi-mechanistic toxicokinetic (TK) model of arsenic in human hepatocytes with a cellular-level toxicodynamic (TD) model describing the arsenic-induced reactive oxygen species (ROS) burst, the antioxidant response, and the oxidative DNA damage repair process. The antioxidant response mechanism is described based on the Keap1-independent Nuclear Factor-erythroid 2-related factor 2 (Nrf2) signaling cascade and accounts for the upregulation of detoxifying enzymes. The ROS-induced DNA damage is simulated by coupling the TK/TD formulation with a model describing the multistep pathway of oxidative DNA repair. The predictions of the model are assessed against experimental data of arsenite-induced genotoxic damage to human hepatocytes; thereby capturing in silico the mode of the experimental dose-response curve. CONCLUSIONS: The integrated cellular-level TK/TD model presented here provides significant insight into the underlying regulatory mechanism of Nrf2-regulated antioxidant response due to arsenic exposure. While computational simulations are in a fair good agreement with relevant experimental data, further analysis of the system unravels the role of a dynamic interplay among the feedback loops of the system in controlling the ROS upregulation and DNA damage response. This TK/TD framework that uses arsenic as an example can be further extended to other toxic or pharmaceutical agents.",
Arsenic,1508685,"Yeast Gis2 and its human ortholog CNBP are novel components of stress-induced RNP granules Abstract: Although a CCTG expansion in the gene encoding the zinc knuckle protein CNBP causes a common form of muscular dystrophy, the function of both human CNBP and its putative budding yeast ortholog Gis2 remain poorly understood. Here we report the protein interactions of Gis2 and the subcellular locations of both Gis2 and CNBP. We found that Gis2 exhibits RNA-dependent interactions with two proteins involved in mRNA recognition, the poly(A) binding protein and the translation initiation factor eIF4G. We show that Gis2 is a component of two large RNA-protein granules, processing bodies and stress granules, which contain translationally repressed mRNAs. Consistent with a functional ortholog, CNBP also associates with the poly(A) binding protein and accumulates in stress granules during arsenite treatment of human cells. These results implicate both Gis2 and CNBP in mRNA handling during stress.",
Arsenic,2088364,"Chronic respiratory symptoms in children following in utero and early life exposure to arsenic in drinking water in Bangladesh Abstract: <strong>BACKGROUND: </strong>Arsenic exposure via drinking water increases the risk of chronic respiratory disease in adults. However, information on pulmonary health effects in children after early life exposure is limited.<br /><br /><strong>METHODS: </strong>This population-based cohort study set in rural Matlab, Bangladesh, assessed lung function and respiratory symptoms of 650 children aged 7-17 years. Children with in utero and early life arsenic exposure were compared with children exposed to less than 10 µg/l in utero and throughout childhood. Because most children drank the same water as their mother had drunk during pregnancy, we could not assess only in utero or only childhood exposure.<br /><br /><strong>RESULTS: </strong>Children exposed in utero to more than 500 µg/l of arsenic were more than eight times more likely to report wheezing when not having a cold [odds ratio (OR) = 8.41, 95% confidence interval (CI): 1.66-42.6, P &lt; 0.01] and more than three times more likely to report shortness of breath when walking on level ground (OR = 3.86, 95% CI: 1.09-13.7, P = 0.02) and when walking fast or climbing (OR = 3.19, 95% CI: 1.22-8.32, P &lt; 0.01]. However, there was little evidence of reduced lung function in either exposure category.<br /><br /><strong>CONCLUSIONS: </strong>Children with high in utero and early life arsenic exposure had marked increases in several chronic respiratory symptoms, which could be due to in utero exposure or to early life exposure, or to both. Our findings suggest that arsenic in water has early pulmonary effects and that respiratory symptoms are a better marker of early life arsenic toxicity than changes in lung function measured by spirometry.",
Arsenic,1021205,"Oxidative mechanism of arsenic toxicity and carcinogenesis Abstract: Arsenic is a known toxin and carcinogen that is present in industrial settings and in the environment. The mechanisms of disease initiation and progression are not fully understood. In the last a few years, there has been increasing evidence of the correlation between the generation of reactive oxygen species (ROS), DNA damage, tumor promotion, and arsenic exposure. This article summarizes the current literature on the arsenic mediated generation of ROS and reactive nitrogen species (RNS) in various biological systems. This article also discusses the role of ROS and RNS in arsenic-induced DNA damage and activation of oxidative sensitive gene expression.",
Arsenic,627364,"Influence of antimonite, selenite, and mercury on the toxicity of arsenite in primary rat hepatocytes Abstract: The long-term toxicity of arsenic (As) as a result of exposure to contaminated drinking water might be modified by coinciding exposures to elements like selenium, antimony, or mercury. In this study the influence of tetravalent selenite, trivalent antimonite, and divalent mercury was investigated in vitro using cultured primary rat hepatocytes. The cell vitality was assessed in the 3-[4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide] (MTT), assay with concurrent exposures of the cells to up to 50 microM sodium arsenite(III) and a potential modifier [50 microM sodium(IV) selenite, 10 microM antimony(III) chloride, 25 microM mercuric(II) chloride], which indicated an additive increase in the combined cytotoxicity. Sodium arsenite was tested for genotoxicity in the micronucleus test in a concentration range of 0.25 up to 7.5 microM. In this range, the MTT conversion was at least 80%, indicating high cell viability. Adose-dependent induction of micronuclei was observed. The lowest concentration causing a significantly elevated frequency of micronuclei was 1 microM As (p < 0.05). A significant influence (i.e., reduction of the combined genotoxicity as a result of the presence of a potential modifier) was only observed for 10 and 25 microM antimony chloride (p < 0.05, Fisher's exact test). The metabolic methylation of arsenite was not affected by concurrent incubation with any of the potential modifiers.",
Arsenic,1352225,Characterization of Axial and Proximal Histidine Mutations of the Decaheme Cytochrome MtrA from Shewanella sp Strain ANA-3 and Implications for the Electron Transport System Abstract: ,
Arsenic,2343523,"Minor and trace-elements in apiary products from a historical mining district (Les Malines, France) Abstract: The trace-elements (TE) contents of honey, royal-jelly and beeswax from a historical Zn-Pb mining district have been investigated to assess potential contamination. In spite of high levels of heavy metal (As, Cd, Tl, Pb) in wastes left after mining stopped, apiary products appear to be relatively free of TE contamination. For honey, the following average levels (±standard error) were observed: Zn 571±440?gkg(-1), Pb 26±20?gkg(-1), Tl 13±10?gkg(-1), Cd 7±6?gkg(-1) and As 3±4?g.kg(-1). These results bring additional data to the potential impact of brownfields left after mining on apiary products. They also bring new data to assess potential risks linked with honey consumption and discuss legal TE contents in honey and other food products from apiaries.",
Arsenic,2343500,"Effects of soluble and insoluble fractions from bilberries, black currants, and raspberries on short-chain fatty acid formation, anthocyanin excretion, and cholesterol in rats Abstract: Dietary fiber and flavonoids, important components in berries, are suggested to improve metabolic health. This study investigates whether soluble and insoluble fractions isolated from bilberry, black currant, and raspberry affect the formation of short-chain fatty acids (SCFAs), uptake and excretion of flavonoids, and levels of cholesterol differently. Cecal SCFA pools were higher in rats fed the soluble than the insoluble fractions (525 vs 166 ?mol, P &lt; 0.001), whereas higher concentrations of butyric acid were found in the distal colon and serum of rats fed the insoluble fractions (5 vs 3 ?mol/g and 58 vs 29 ?mol/L, respectively, P < 0.001). The soluble bilberry fraction gave lower amounts of liver cholesterol (56 mg) than the other berry fractions (87 ± 5 mg), formed the highest amount of SCFAs (746 vs 266 ± 21 ?mol), and contributed the highest intake of anthocyanins. Cyanidin-3-glucoside monoglucuronide was detected in the urine of all groups, whereas anthocyanins were found only in groups fed soluble black currant and raspberry.",
Arsenic,1033585,"Arsine generation and determination of trace amounts of arsenic by atomic absorption spectrometry Abstract: Arsenic can be determined by atomic absorption spectrometry after reduction to arsine with potassium iodide, tin(II) chloride and zinc powder tablet; the arsine generated is carried into an argon-hydrogen flame by means of argon. Accuracy, precision and speed are satisfactory. Serious interferences arise only from nitric acid, lead, chromium and selenium.",
Arsenic,2273351,"DEVELOPMENT OF A NEW METHOD FOR THE DETERMINATION OF ARSENIC IN BABY FORMULAS BY USING EXTRACTION METHOD Abstract: The determination of arsenic in five different extraction environments (acetic acid, EDTA, NaOH, MeOH/H2O, acetonitrile) from baby formulas sold in the market was tested. Total arsenic contents were analyzed with Flow Injection-Hydride Generation-Atomic Absorption Spectrometry (FI-HG-AAS) and Graphite Furnace-Atomic Absorption Spectrometry (GF-AAS) after digestion of samples with nitric acid using a microwave sample digestion system. In order to verify accuracy and certainty of the analytical method applied, soy flours known as FAPAS 770 and FAPAS 787 were used as standard reference materials. The most efficient extraction was achieved with 5M NaOH (recovery rate > 98 %).",
Arsenic,1015804,"An attempt to electrically enhance phytoremediation of arsenic contaminated water Abstract: Water polluted with arsenic presents a challenge for remediation. A combination of phyto- and electro-remediation was attempted in this study. Four tanks were setup in order to assess the arsenic removal ability of the two methods separately and in combination. Lemna minor was chosen for As remediation and collected from a ditch in Utrecht, The Netherlands. The tanks were filled with surface water without any pre-cleaning, therefore containing various elements including metals as Mn (2.9mgL(-1)), Cu (0.05mgL(-1)), Fe (1.39mgL(-1)), and Ba (0.13mgL(-1)). This water was then spiked with As and allocated to a feed container, guaranteeing a continuous flow of 0.12mLs(-1) to each tank. Two experiments were performed: Exp. 1 with 3 consecutive stages with rising applied voltage and Exp. 2, with a constant voltage over a period of 6d. Measurements of pH and temperature were taken every working day, as well as water samples from outlets of all tanks including feed container for control. From the present study, there was no evidence that As had been taken up by the plants, but a strong depletion of As was observed in the tanks where current was applied. Preliminary results clearly showed that applying voltage to the electrodes caused 90% removal of As from the spiked surface water.",
Arsenic,1337319,"Efficiency of Silver Impregnated Porous Pot (SIPP) Filters for Production of Clean Potable Water Abstract: The Silver Impregnated Porous Pot (SIPP) filter is a product of the Tshwane University of Technology manufactured for the production of safe drinking water at a household (home) level. Two SIPP devices were assessed for the reduction efficiency of chemical contaminants such as calcium, magnesium, iron, arsenic, fluorides and total organic carbon (TOC) as well as microbial contaminants from environmental samples. Turbidity change after filtration, together with correlation between chlorophyll a in the feed water and SIPP's flow rates were also evaluated in order to give comprehensive guidelines on the quality of intake water that could be filtered through the filter without causing a significant decrease in flow rate. The SIPP filters removed contaminants from environmental water samples as follows: 70% to 92% iron, 36% to 68% calcium, 42% to 82% arsenic, 39% to 98% magnesium, 39% to 95% fluorides, 12% to 35% TOC and 45% to 82% turbidity. The SIPP filters had initial flow rates of 1 L/h to 4 L/h but the flow rates dropped to 0.5 L/h with an increase in cumulative volume of intake water as the filter was used. Turbidity and chemical contaminant reduction rates decreased with accumulating volume of intake water but the filter removed Ca, Fe and Mg to levels that comply with the South African National Standards (SANS 241) and the World Health Organization (WHO) guideline values. However, the SIPP filters cannot produce enough water to satisfy the daily drinking water requirement of a typical household (25 L/p·d). Chlorophyll a was associated with a decrease in the flow rate through the SIPP filters.",
Arsenic,1032456,"Heat shock proteins in cultured human keratinocytes and fibroblasts Abstract: Heat shock induces in cells the synthesis of specific proteins called heat-shock proteins. We have compared the induction of these proteins in human keratinocytes, skin fibroblasts, and a human epithelial tumor cell line following exposure to weak and strong inducing agents (heat, cadmium sulphate, and sodium arsenite). The induction of heat shock proteins was measured in cells by one-dimensional gel electrophoresis of [35S] methionine-labeled proteins and by immunofluorescence using a specific HSP72 monoclonal antibody. Both HSP90 and HSP116 were constitutively expressed in these cell types. Exposure of these cells to weak inducing agents such as heat or cadmium sulphate resulted in the synthesis of HSP72 and HSP90, whereas HSP28 and HSP116 synthesis was detected in keratinocytes and fibroblasts following exposure to the strong inducing agent sodium arsenite. In addition, sodium arsenite induced the synthesis of HSP46 in human keratinocytes. Immunofluorescence demonstrated a rapid and reversible accumulation of the 72-kD heat shock protein within the nucleolus of heat-stressed human keratinocytes and fibroblasts.",
Arsenic,2278647,"Metals in Honeys from Different Areas of Southern Italy Abstract: The aim of the study was to quantify the cadmium (Cd), lead (Pb), chromium (Cr) and arsenic (As) contents in ninety honey samples from nine areas of southern Italy. Results showed that As content was below the detection limit, while Cd, Pb, and Cr contents were below the recommended maximum acceptable levels. Mean Cd, Pb, and Cr contents were 0.013, 0.289 and 0.707 mg kg(-1), respectively. The metal contents in honey varied greatly depending on considered area. Correlations between the metals were statistically significant (p &lt; 0.05), suggesting that polluting sources involve the simultaneous presence of metals in honey.",
Arsenic,1597345,"Dietary arsenic intake and subsequent risk of cancer: The Japan Public Health Center-based (JPHC) prospective study Abstract: PURPOSE: Arsenic is a known human carcinogen and has been linked to adverse health outcomes, including cancer. However, the effects of arsenic exposure from food on health are still unknown. We researched to examine the association between arsenic exposure from food and incidence of cancer in a Japanese population. METHODS: We conducted a population-based prospective study in 90,378 Japanese men and women aged 45-74 years. Participants responded to a validated questionnaire that included 138 food items. We estimated dietary arsenic intake from 12 food groups (75 items) based on the questionnaire data. During 11 years of follow-up, 7,002 cancer cases were identified. Hazard ratios (HRs) and 95 % confidence intervals (CIs) for cancer were calculated by Cox proportional hazards modeling. RESULTS: Total arsenic and inorganic arsenic showed no association with the risk of total cancer in both men and women. Total arsenic and inorganic arsenic intake tended to be associated with an increased risk of lung cancer in men. In particular, these positive associations were strengthened in currently smoking men, with HRs (95 % CI) in the highest categories of arsenic and inorganic arsenic intake compared with the lowest of 1.29 (95 % CI = 1.03-1.61) and 1.36 (95 % CI = 1.09-1.70), respectively. We also detected an interaction between arsenic and inorganic arsenic intake and smoking status in men (p interaction < 0.01 and 0.07, respectively). CONCLUSION: A significant dose-response trend was seen in the association of arsenic and inorganic intake with lung cancer risk in currently smoking men.",
Arsenic,1034572,"Ultrastructural and biochemical effects of prolonged oral arsenic exposure on liver mitochondria of rats Abstract: This investigation was undertaken to further delineate the subcellular manifestations of arsenic toxicity following chronic exposure using combined ultrastructural and biochemical techniques. Male rats were given access to deionized drinking water solutions containing 0, 20, 40, or 85 arsenic as arsenate (As(+5)) for 6 weeks. In situ swelling of liver mitochondria was the most prominent ultrastructural change observed. Mitochondrial respiration studies indicated decreased state 3 respiration and respiratory control ratios (RCR) for pyruvate/malate but not succinate mediated respiration. Specific activity of monoamine oxidase which is localized on the outer mitochondrial membrane showed increases of up to 150% of control and cytochrome-C oxidase which is localized on the inner mitochondrial membrane showed increases in specific activity of 150-200%. Activity of malate dehydrogenase which is localized in the mitochondrial matrix was unchanged at any dose level. These studies indicate that decreased mitochondrial respiration is only one aspect of arsenic toxicity to this organelle. Marked arsenic-mediated perturbation of important enzyme systems localized in mitochondria which participate in the control of respiration and other normal mitochondrial functions are also important manifestations of cellular dysfunction.",
Arsenic,627272,"Arsenic trioxide induces apoptosis of human monocytes during macrophagic differentiation through nuclear factor-?B-related survival pathway down-regulation Abstract: Arsenic trioxide (As(2)O(3)) is known to be toxic toward leukemia cells. In this study, we determined its effects on survival of human monocytic cells during macrophagic differentiation, an important biological process involved in the immune response. As(2)O(3) used at clinically relevant pharmacological concentrations induced marked apoptosis of human blood monocytes during differentiation with either granulocyte-macrophage colony-stimulating factor or macrophage colony-stimulating factor. Apoptosis of monocytes was associated with increased caspase activities and decreased DNA binding of p65 nuclear factor-kappaB (NF-kappaB); like As(2)O(3), the selective NF-kappaB inhibitor (E)-3-[(4-methylphenyl)-sulfonyl]-2-propenenitrile (Bay 11-7082) strongly reduced survival of differentiating monocytes. The role of NF-kappaB in arsenic toxicity was also studied in promonocytic U937 cells during phorbol 12-myristate 13-acetate-induced macrophagic differentiation. In these cells, As(2)O(3) first reduced DNA binding of p65 NF-kappaB and subsequently induced apoptosis. In addition, overexpression of the p65 NF-kappaB subunit, following stable infection with a p65 retroviral expressing vector, increased survival of As(2)O(3)-treated U937 cells. As(2)O(3) specifically decreased protein levels of X-linked inhibitor of apoptosis protein and FLICE-inhibitory protein, two NF-kappaB-regulated genes in both U937 cells and blood monocytes during their differentiations. Finally, As(2)O(3) was found to inhibit macrophagic differentiation of monocytic cells when used at cytotoxic concentrations; however, overexpression of the p65 NF-kappaB subunit in U937 cells reduced its effects toward differentiation. In contrast to monocytes, well differentiated macrophages were resistant to low concentrations of As(2)O(3). Altogether, our study demonstrates that clinically relevant concentrations of As(2)O(3) induced marked apoptosis of monocytic cells during in vitro macrophagic differentiation likely through inhibition of NF-kappaB-related survival pathways.",
Arsenic,1026537,"Arsenic induced oxidative stress and the role of antioxidant supplementation during chelation: a review Abstract: Arsenic is a naturally occurring metalloid, ubiquitously present in the environment in both organic and inorganic forms. Arsenic contamination of groundwater in the West Bengal basin in India is unfolding as one of the worst natural geoenvironmental disaster to date. Chronic exposure of humans to high concentration of arsenic in drinking water is associated with skin lesions, peripheral vascular disease, hypertension, Blackfoot disease and high risk of cancer The underlying mechanism of toxicity includes the interaction with the sulphydryl groups and the generation of reactive oxygen species leading to oxidative stress. Chelation therapy with chelating agents like British Anti Lewisite (BAL), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), meso 2,3 dimercaptosuccinic acid (DMSA) etc., is considered to be the best known treatment against arsenic poisoning. The treatment with these chelating agents however is compromised with certain serious drawbacks/side effects. The studies show that supplementation of antioxidants along with a chelating agent prove to be a better treatment regimen. This review attempts to provide the readers with a comprehensive account of recent developments in the research on arsenic poisoning particularly the role of oxidative stress/free radicals in the toxic manifestation, an update about the recent strategies for the treatment with chelating agents and a possible beneficial role of antioxidants supplementation to achieve the optimum effects.",
Arsenic,1353897,"A geochemical assessment of the middle and lower Mvoti river system, KwaZulu-Natal, South Africa Abstract: ",
Arsenic,1519204,"Arsenic accumulation and distribution in the tissues of inbred lines in maize (Zea mays L.) Abstract: We investigated arsenic (As) accumulation and distribution in four different tissues of maize, leaves, stems, bracts, and kernels. For these analyses, we used 122 elite inbred lines, which were grown in an As-contaminated area in China. The agricultural soil at the study site is highly As-contaminated (11.02 ± 0.95 mg As kg soil?1) because of excessive use of As-rich surface water for irrigation. The As concentration in the leaves was significantly positively correlated with that in stems and kernels, and the As concentration in the stems was significantly positively correlated with that in the kernels. In the 122 inbred lines, the highest average As concentration was in the leaves, followed by the stems, the bracts, and then the kernels. The range of As concentrations in leaves, stems, bracts, and kernels of the 122 inbred lines was 0.13–1.48, 0.017–0.145, 0.013–0.131, and 0.0001–0.0408 mg As kg?1, respectively. The inbred lines with low As concentrations in the kernels perhaps could be used as a parent to select an elite hybrid with low As concentration for decreasing the As damage for people and animal.",
Arsenic,471141,"Monoisoamyl dimercaptosuccinic acid abrogates arsenic-induced developmental toxicity in human embryonic stem cell-derived embryoid bodies: Comparison with in vivo studies Abstract: The ability of human embryonic stem (ES) cells to differentiate into the three germ layers has proposed its application in studying human developmental toxicity in vitro. In the current study we investigated if the prompted application could be utilized to evaluate the efficacy of a newly developed arsenic antidote, monoisoamyl dimercaptosuccinic acid (MiADMSA) against arsenic (III) and if the results obtained in vitro were in concordance with the animal model for studying developmental toxicity. On the basis of real time PCR (qRT-PCR) and cytotoxicity analysis of human embryoid bodies (EBs), we observed that arsenic (III) caused a significant down regulation of gene expression in all the three germ layers, which could be correlated with high mortality, visceral and skeletal defects in pups. Reversal of arsenic-induced dysfunctioning could be observed with concomitant treatment of MiADMSA in vitro and in vivo, indicating ES-EB model could provide toxicity information similar to in vivo model. IR spectroscopy further suggested that MiADMSA bind to arsenic to form adduct, which prevents arsenic from exerting its toxic effect in both models. To our knowledge this study provides first experimental evidence suggesting human ES cells could be utilized in studying the efficacy of drugs in a comparable manner with animal models. We conclude that the ES-EB model seems to be an effective, faster, cost effective method for predicting efficacy of a drug. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,627038,"Butylhydroquinone protects cells genetically deficient in glutathione biosynthesis from arsenite-induced apoptosis without significantly changing their prooxidant status Abstract: Arsenic, first among the top environmentally hazardous substances, is associated with skin, lung, liver, kidney, prostate, and bladder cancer. Arsenic is also a cardiovascular and a central nervous system toxicant, and it has genotoxic and immunotoxic effects. Paradoxically, arsenic trioxide is used successfully in the treatment of acute promyelocytic leukemia and multiple myeloma. Arsenic induces oxidative stress, and its toxicity is decreased by free thiols and increased by glutathione depletion. To further characterize the role of glutathione and oxidative stress in the toxicity of arsenic, we have used fetal fibroblasts from Gclm(-/-) mice, which lack the modifier subunit of glutamate-cysteine ligase, the rate-limiting enzyme in glutathione biosynthesis. Gclm(-/-) mouse embryo fibroblasts (MEFs) are eight times more sensitive to arsenite-induced apoptotic death. Because of a dramatic decrease in glutathione levels, Gclm(-/-) MEFs have a high prooxidant status that is not significantly relieved by treatment with the phenolic antioxidant tBHQ; however, tBHQ blocks arsenite-induced apoptosis in both Gclm(+/+) and Gclm(-/-) cells, although it raises a significant antioxidant response only in Gclm(+/+) cells. Global gene expression profiles indicate that tBHQ is significantly effective in reversing arsenite-induced gene deregulation in Gclm(+/+) but not in Gclm(-/-) MEFs. This effect of tBHQ is evident in the expression of metalloproteases and chaperones, and in the expression of genes involved in DNA damage and repair, protein biosynthesis, cell growth and maintenance, apoptosis, and cell cycle regulation. These results suggest that regulation of glutathione levels by GCLM determines the sensitivity to arsenic-induced apoptosis by setting the overall ability of the cells to mount an effective antioxidant response.",
Arsenic,1337539,"Role of arsenic (+3 oxidation state) methyltransferase in arsenic metabolism and toxicity Abstract: The metabolism of arsenicals, including their reduction and methylation has been extensively studied, and both classical and novel pathways of arsenic methylation are proposed. Arsenic methylation has been considered to be a detoxification process of inorganic arsenicals, although recent studies have indicated that trivalent methylated arsenicals, the intermediate products of arsenic methylation, are more toxic than inorganic arsenicals. In 2002, arsenite (+3 oxidation state) methyltransferase (As3MT) was discovered to be an enzyme responsible for arsenic methylation. This review focuses on current information on the function, genetic polymorphism, and alternative splicing of As3MT, all of which contribute to arsenic metabolism and toxicity.",
Arsenic,1519098,"Role of gastric lavage in vigorous neonates born with meconium stained amniotic fluid Abstract: <strong>OBJECTIVE: </strong>To compare reduction in incidence of feed intolerance in neonates born with meconium stained amniotic fluid (MSAF) by use of gastric lavage to those who did not receive lavage.<br /><br /><strong>METHODS: </strong>This Randomized controlled trial was conducted in all vigorous newborns delivered through MSAF, with birth weight ?1800 g and gestation ?34 wk. In the lavage group, gastric lavage with 10 ml/kg of normal saline was done.<br /><br /><strong>RESULTS: </strong>Twelve neonates in the lavage group (n?=?124) developed feed intolerance compared to 16 neonates in control group (n?=?120), (p?=?.309; OR 0.69; 95%CI 0.27-1.58). No difference in any other morbidity was noted.<br /><br /><strong>CONCLUSIONS: </strong>Gastric lavage in neonates with MSAF does not reduce feed intolerance, irrespective of thickness of MSAF and it confers no advantages.",
Arsenic,1346433,Polyphenols of Mangifera indica modulate arsenite-induced cytotoxicity in a human proximal tubule cell line Abstract: ,
Arsenic,2298695,"Adsorption and photocatalytic decomposition of roxarsone by TiO2 and its mechanism Abstract: Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) has been widely used as organic arsenic additive in animal industry. In this study, the adsorption of roxarsone on TiO2 under dark conditions, the photocatalytic decomposition of roxarsone under UV/TiO2, and the possible photocatalytic pathway were investigated. At the initial concentration of 5-35 mg/L, the adsorption of roxarsone fitted well with the pseudo-second-order kinetics. The isotherms analysis showed that the Langmuir model was better than the Freundlich and Dubinin-Radushkevich models for describing the adsorption process. After 7 h of photocatalytic decomposition, a complete disappearance of roxarsone was achieved. The pH value has a significant effect on both adsorption and photocatalytic decomposition of roxarsone. The results of high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) and gas chromatography-mass spectrometry (GC/MS) analyses proved the cleavage of the As-C bond during the photocatalytic decomposition process by TiO2 and the intermediates of the decomposition. Based on the results, a possible photocatalytic decomposition pathway was proposed.",
Arsenic,1024374,"A new method for radiochemical separation of arsenic from irradiated germanium oxide Abstract: Radioarsenic labelled radiopharmaceuticals could be a valuable asset to Positron Emission Tomography (PET). In particular, the long half-lives of (72)As (T(1/2)=26 h) and (74)As (T(1/2)=17.8 d) allow to investigate slow physiological or metabolical processes, like the enrichment and distribution of antibodies in tumor tissue. This work describes the direct production of no-carrier-added (nca) arsenic isotopes *As, with *=71, 72, 73, 74 or 77, the reaction to [*As]AsI(3) and its radiochemical separation from the irradiated solid germanium oxide via polystyrene-based solid-phase extraction. The germanium oxide target, irradiated at a cyclotron or a nuclear reactor, is dissolved in concentrated HF and Ge is separated almost quantitatively (99.97%) as [GeF(6)](2-). [*As]AsI(3) is formed by addition of potassium iodide. The radiochemical separation yield for arsenic is &gt;90%. [*As]AsI(3) is a versatile radioarsenic labelling synthon.",
Arsenic,656867,"Arsenic and benzo[a]pyrene differentially alter the capacity for differentiation and growth properties of primary human epidermal keratinocytes Abstract: Normal human epidermal keratinocytes (NHEK) have been chosen as an in vitro model to test the hypothesis that chemicals which alter or interfere in cellular differentiation will concomitantly induce growth perturbations and are, thus, potential carcinogens. In these studies, we have focused on two known skin carcinogens, arsenic and benzo(a)pyrene (BaP). Our results demonstrated that BaP inhibits terminal differentiation in NHEK, as measured by cross-linked envelope (CLE) formation, up to 5.8-fold in control and 1.7-fold in calcium (Ca2+)-treated cells. In comparison, arsenic decreased CLE formation 20-fold in control cells and 5.5-fold in Ca2+-treated NHEK. To characterize the effects of these agents on the growth rate and cell cycle distributions of NHEK, flow cytometric analysis was used. BaP at 2 microM increased proliferation rates by 29%. Altered cell-cycle distribution in BaP-treated cells indicated a more rapid progression through the cell cycle, possibly by a shortened G2 phase. In contrast, arsenic at 5 microM inhibited proliferation by 25%; growth arrest (9%) was also observed in NHEK treated with 2 mM Ca2+. Our findings suggest that, although both BaP and arsenic inhibit CLE production in NHEK, different mechanisms may be involved. Studies in progress will attempt to identify molecular markers involved in the observed chemical effects. These markers will facilitate a mechanistic understanding of how an altered balance between growth and differentiation may play a role in the transformation process in NHEK.",
Arsenic,2088332,"Electrochemical behaviour of arsenic on copper deposition reaction in the low copper concentration electrolyte Abstract: During the electrolytic refining process of copper, arsenic as a common impurity ions, would affect the deposition reaction of the copper cathodes and thereby affected the quality of the cathode copper. In this paper, linear sweep voltammetry and cyclic voltammetry were used to analyze the electrochemical behaviour of arsenic ion in the low-copper electrolyte system. The effect of arsenic ion impacting the limiting current density in copper deposition, as well as co-deposition reaction mechanism on the cathode copper were also studied, which would provide a theoretical basis on the actual improvements of copper electrolysis process.",
Arsenic,628655,"Arsenite inhibits p53 phosphorylation, DNA binding activity, and p53 target gene p21 expression in mouse epidermal JB6 cells Abstract: Epidemiologic investigations demonstrated that arsenite exposure increases the risk of various human cancers, including skin, lung, bladder, and kidney cancers. However, oral administration of arsenite alone has failed to induce tumors in animal models, suggesting that arsenic may act to enhance mutagenicity induced by other carcinogens. Arsenite may function as a co-carcinogen, acting by inhibiting repair of carcinogen-induced DNA damage mediated by p53 and p21, a p53 target gene. To elucidate the interaction between arsenite and p53 tumor suppressor protein, we studied the effect of arsenite on ultraviolet B (UVB)-induced p53 phosphorylation, p53 DNA binding activity, and p53-induced target gene transactivation in the JB6 Cl41 mouse epidermal skin cell model. Our results indicated that arsenite suppressed UVB-induced p53 phosphorylation and p53 DNA binding activity. Arsenite also inhibited casein kinase 2 (CK2) activity and decreased p53-regulated p21 protein expression. These data suggest that the direct inhibition of p53 functional activation is one of the mechanisms through which arsenite interferes with p53 function, and thus may be a significant mechanism for the co-carcinogenic effects of arsenite.",
Arsenic,2345634,"Determination of toxic heavy metals in Echinodermata and Chordata species from South Korea Abstract: This study aimed at analysing concentrations of heavy metals including arsenic, lead, cadmium, aluminium and mercury in commonly consumed seafood species belonging to Echinodermata (Anthocidaris crassispina and Stichopus japonicus) and Chordata (Halocynthia roretzi and Styela plicata). The samples were digested by a microwave system and analysed for As, Cd and Pb by inductively coupled plasma mass spectrometer, for Al by inductively coupled plasma-optical emission spectrometer and Hg by Direct Mercury Analyser. The analytical method was validated by determining sensitivity, linearity, precision, spiking recoveries and analysis of the Standard Reference Material (SRM) NIST 1566-b, an Oyster Tissue. Results showed considerably higher accumulation of Al and As in analysed samples, compared to Pb and Cd, while Hg had the lowest contamination. On comparison, the obtained results with the recommended standards by the Food and Agriculture Organization, European Commission and Ministry of Food and Drug Safety of Korea, it was concluded that the analysed seafoods were safe and thus would not pose a threat to consumers.",
Arsenic,1936105,"Facile template-free fabrication of hollow nestlike ?-Fe?O? nanostructures for water treatment Abstract: Hollow nestlike ?-Fe(2)O(3) spheres were successfully synthesized via a facile template-free, glycerol-mediated hydrothermal process employing microwave heating. The product was characterized using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption measurements. The as-prepared product was found to consist of hierarchically nanostructured spheres assembled of nanorod subunits. The effect of the relative amount of glycerol in the reaction system on the composition and morphology of the products was systematically studied, and a possible formation mechanism of the hollow nestlike spheres was proposed. Because of their large surface area and unique mesoporous structure, we investigated the potential application of the hollow ?-Fe(2)O(3) spheres in water treatment. With maximum removal capacities of 75.3, 58.5, and 160 mg g(-1) for As(V), Cr(VI), and Congo red, respectively, these novel nanostructures have the potential to be used as low-cost and efficient adsorbent materials for the removal of toxic metal ions and organic pollutants from water.",
Arsenic,2088363,"Contents of fluoride, lead, copper, chromium, arsenic and cadmium in Chinese Pu-erh tea Abstract: In order to assess safety for consumers and the levels of contamination in Pu-erh tea, the authors studied the contents of fluoride, lead, copper, chromium, arsenic and cadmium in 56 Chinese samples of Pu-erh tea collected from Dali City, Lincang City, Xishuangbanna City, Simao City and Dehong City in Yunnan province. The ranges obtained for the elements analyzed were 80.2–151.6 mg kg? 1 (fluoride), 0.66–4.66 mg kg? 1 (lead), 14.8–19.3 mg kg? 1 (copper), 1.95–4.98 mg kg? 1 (chromium), 0.07–0.25 mg kg? 1 (arsenic) and 0.023–0.130 mg kg? 1 (cadmium). The mean leached analyte concentrations in tea infusion were 523.86 ?g L? 1 for fluoride, 5.70 ?g L? 1 for lead, 43.18 ?g L? 1 for copper, 13.67 ?g L? 1 for chromium, 0.43 ?g L? 1 for arsenic and 0.17 ?g L? 1 for cadmium after the tea leaves were brewed twice with boil water in a ratio of 1 g/50 ml for 5 min. The mean dissolving rates of fluoride, lead, copper, chromium, arsenic, and cadmium were 45.8%, 24.6%, 26.2%, 35.2%, 30.8% and 27.4%, respectively. Significant differences for the content of the studied elements except copper were generally observed with different Pu-erh tea's habitats. Pu-erh compressed tea had lower lead levels than loose tea. Based on a 70 kg individual consuming 15 g of Pu-erh tea daily or 105 g Pu-erh tea weekly, the dietary intake of the studied elements was below the safe limits recommended by various authorities. This suggested that under the current dietary intake, there are no possible health risks to Pu-erh tea drinking consumers.",
Arsenic,1016877,"Protein levels of escherichia coli thioredoxins and glutaredoxins and their relation to null mutants, growth phase, and function Abstract: Levels of Escherichia coli thioredoxin 1 (Trx1), Trx2, glutaredoxin 1 (Grx1), Grx2, and Grx3 have been determined by novel sensitive sandwich enzyme-linked immunosorbent assay. In a wild type strain, levels of Trx1 increased from the exponential to the stationary phase of growth (1.5-fold to 3400 ng/mg), as did levels of Grx2 (from approximately 2500 to approximately 8000 ng/mg). Grx3 and Trx2 levels were quite stable during growth ( approximately 4500 and approximately 200 ng/mg, respectively). Grx1 levels decreased from approximately 600 ng/mg at the exponential phase to approximately 285 ng/mg at the stationary phase. A large elevation of Grx1 (20-30-fold), was observed in null mutants for the thioredoxin system whereas levels of the other redoxins in all combinations of examined null mutants barely exceeded a 2-3-fold increase. Measurements of thymidine incorporation in newly synthesized DNA suggested that mainly Grx1 and, to a lesser extent, Trx1 contribute to the reduction of ribonucleotides. All glutaredoxin species were elevated in catalase-deficient strains, implying an antioxidant role for the glutaredoxins. Trx1, Trx2, and Grx1 levels increased after exposure to hydrogen peroxide and decreased after exposure to mercaptoethanol. The levels of Grx2 and Grx3 behaved exactly the opposite, suggesting that the transcription factor OxyR does not regulate their expression.",
Arsenic,1519030,"Arkadia, a novel SUMO-targeted ubiquitin ligase involved in PML degradation Abstract: Arkadia is a RING domain E3 ubiquitin ligase that activates the transforming growth factor-? (TGF-?) pathway by inducing degradation of the inhibitor SnoN/Ski. Here we show that Arkadia contains three successive SUMO interacting motifs (SIMs) that mediate non-covalent interaction with poly-SUMO2. We identify the third SIM motif (VVDL) of Arkadia as the most relevant one in this interaction. Furthermore we provide evidence that Arkadia can function as a SUMO-targeted ubiquitin ligase (STUBL) by ubiquitinating SUMO chains. While the SIMs of Arkadia are not essential for SnoN/Ski degradation in response to TGF-?, we show that they are necessary for the interaction of Arkadia with poly-sumoylated PML in response to arsenic and its concomitant accumulation into PML nuclear bodies. Moreover, Arkadia depletion leads to accumulation of poly-sumoylated PML in response to arsenic, highlighting a requirement of Arkadia for arsenic-induced degradation of poly-sumoylated PML. Interestingly, Arkadia homodimerizes but does not heterodimerize with RNF4, the other STUBL involved in PML degradation, suggesting that these two E3s do not act synergistically, but most probably independently during this process. Altogether, these results identify Arkadia as a novel STUBL that can trigger degradation of signal-induced poly-sumoylated proteins.",
Arsenic,1677533,"Knock-in/Knock-out (KIKO) vectors for rapid integration of large DNA sequences, including whole metabolic pathways, onto the Escherichia coli chromosome at well-characterised loci Abstract: <strong>BACKGROUND: </strong>Metabolic engineering projects often require integration of multiple genes in order to control the desired phenotype. However, this often requires iterative rounds of engineering because many current insertion approaches are limited by the size of the DNA that can be transferred onto the chromosome. Consequently, construction of highly engineered strains is very time-consuming. A lack of well-characterised insertion loci is also problematic.<br /><br /><strong>RESULTS: </strong>A series of knock-in/knock-out (KIKO) vectors was constructed for integration of large DNA sequences onto the E. coli chromosome at well-defined loci. The KIKO plasmids target three nonessential genes/operons as insertion sites: arsB (an arsenite transporter); lacZ (beta-galactosidase); and rbsA-rbsR (a ribose metabolism operon). Two homologous 'arms' target each insertion locus; insertion is mediated by lamda Red recombinase through these arms. Between the arms is a multiple cloning site for the introduction of exogenous sequences and an antibiotic resistance marker (either chloramphenicol or kanamycin) for selection of positive recombinants. The resistance marker can subsequently be removed by flippase-mediated recombination. The insertion cassette is flanked by hairpin loops to isolate it from the effects of external transcription at the integration locus. To characterize each target locus, a xylanase reporter gene (xynA) was integrated onto the chromosomes of E. coli strains W and K-12 using the KIKO vectors. Expression levels varied between loci, with the arsB locus consistently showing the highest level of expression. To demonstrate the simultaneous use of all three loci in one strain, xynA, green fluorescent protein (gfp) and a sucrose catabolic operon (cscAKB) were introduced into lacZ, arsB and rbsAR respectively, and shown to be functional.<br /><br /><strong>CONCLUSIONS: </strong>The KIKO plasmids are a useful tool for efficient integration of large DNA fragments (including multiple genes and pathways) into E. coli. Chromosomal insertion provides stable expression without the need for continuous antibiotic selection. Three non-essential loci have been characterised as insertion loci; combinatorial insertion at all three loci can be performed in one strain. The largest insertion at a single site described here was 5.4 kb; we have used this method in other studies to insert a total of 7.3 kb at one locus and 11.3 kb across two loci. These vectors are particularly useful for integration of multigene cassettes for metabolic engineering applications.",
Arsenic,2347576,"Heterologous expression of Ceratophyllum demersum phytochelatin synthase, CdPCS1, in rice leads to lower arsenic accumulation in grain Abstract: Recent studies have identified rice (Oryza sativa) as a major dietary source of inorganic arsenic (As) and poses a significant human health risk. The predominant model for plant detoxification of heavy metals is complexation of heavy metals with phytochelatins (PCs), synthesized non-translationally by PC synthase (PCS) and compartmentalized in vacuoles. In this study, in order to restrict As in the rice roots as a detoxification mechanism, a transgenic approach has been followed through expression of phytochelatin synthase, CdPCS1, from Ceratophyllum demersum, an aquatic As-accumulator plant. CdPCS1 expressing rice transgenic lines showed marked increase in PCS activity and enhanced synthesis of PCs in comparison to non-transgenic plant. Transgenic lines showed enhanced accumulation of As in root and shoot. This enhanced metal accumulation potential of transgenic lines was positively correlated to the content of PCs, which also increased several-fold higher in transgenic lines. However, all the transgenic lines accumulated significantly lower As in grain and husk in comparison to non-transgenic plant. The higher level of PCs in transgenic plants relative to non-transgenic presumably allowed sequestering and detoxification of higher amounts of As in roots and shoots, thereby restricting its accumulation in grain.",
Arsenic,1025980,"Modeling the probability of arsenic in groundwater in New England as a tool for exposure assessment Abstract: We developed a process-based model to predict the probability of arsenic exceeding 5 microg/L in drinking water wells in New England bedrock aquifers. The model is being used for exposure assessment in an epidemiologic study of bladder cancer. One important study hypothesis that may explain increased bladder cancer risk is elevated concentrations of inorganic arsenic in drinking water. In eastern New England, 20-30% of private wells exceed the arsenic drinking water standard of 10 micrograms per liter. Our predictive model significantly improves the understanding of factors associated with arsenic contamination in New England. Specific rock types, high arsenic concentrations in stream sediments, geochemical factors related to areas of Pleistocene marine inundation and proximity to intrusive granitic plutons, and hydrologic and landscape variables relating to groundwater residence time increase the probability of arsenic occurrence in groundwater. Previous studies suggest that arsenic in bedrock groundwater may be partly from past arsenical pesticide use. Variables representing historic agricultural inputs do not improve the model, indicating that this source does not significantly contribute to current arsenic concentrations. Due to the complexity of the fractured bedrock aquifers in the region, well depth and related variables also are not significant predictors.",
Arsenic,1936156,Element distribution imaging in rat kidney using a 2D rapid scan EDXRF device Abstract: ,
Arsenic,2088588,"Methylarsonous acid causes oxidative DNA damage in cells independent of the ability to biomethylate inorganic arsenic Abstract: Inorganic arsenic (iAs) and its toxic methylated metabolite, methylarsonous acid (MMA(III)), both have carcinogenic potential. Prior study shows iAs-induced malignant transformation in both arsenic methylation-proficient (liver) and methylation-deficient (prostate) cells, but only methylation-proficient cells show oxidative DNA damage (ODD) during this transformation. To further define whether arsenic methylation is necessary for transformation or ODD induction, here we chronically exposed these same liver or prostate cell lines to MMA(III) (0.25-1.0 ?M) and tested for acquired malignant phenotype. Various metrics of oncogenic transformation were periodically assessed along with ODD during chronic MMA(III) exposure. Methylation-deficient and methylation-proficient cells both acquired a cancer phenotype with MMA(III) exposure at about 20 weeks, based on increased matrix metalloproteinase secretion, colony formation, and invasion. In contrast, prior work showed iAs-induced transformation took longer in biomethylation-deficient cells (~30 weeks) than in biomethylation-proficient cells (~18 weeks). In the present study, MMA(III) caused similar peak ODD levels at similar concentrations and at similar exposure times (18-22 weeks) in both cell types. At the approximate peak of ODD production, both cell types showed similar alterations in arsenic and oxidative stress adaptation factors (i.e., ABCC1, ABCC2, GST-?, SOD-1). Thus, MMA(III) causes oncogenic transformation associated with ODD in methylation-deficient cells, indicating that further methylation is not required to induce ODD. Together, these results show that MMA(III) and iAs cause an acquired malignant phenotype in methylation-deficient cells, yet iAs does not induce ODD. This indicates iAs likely has both genotoxic and non-genotoxic mechanisms dictated by the target cell's ability to methylate arsenic.",
Arsenic,1351254,"Characterization of human NIPK (TRB3, SKIP3) gene activation in stressful conditions Abstract: The neuronal cell death-inducible putative kinase (NIPK) gene is upregulated in several cell types under stressful conditions. In order to understand the molecular control of the human (h) NIPK gene (also known as TRB3 and SKIP3), we mapped the transcriptional start sites of the gene in HepG2 cells treated with thapsigargin, the inhibitor of endoplasmic reticular Ca(2+)-ATPase, and determined the promoter region of the gene which is essential for endoplasmic reticulum and arsenite stress responses. The analysis of cDNA clones revealed the presence of several hNIPK mRNA isoforms, differing in their 5' regions upstream of the hNIPK translation initiation codon as a result of alternative transcription initiation and alternative splicing. The induction of hNIPK gene in response to thapsigargin and arsenite treatments is mediated by a promoter segment consisting of tandemly arranged 33-bp repeats that contain a regulatory element similar to C/EBP-ATF composite site of the Chop gene promoter. ATF4, whose level is upregulated in the cells exposed to thapsigargin or arsenite, is able to bind to the 33-bp repeat and activate the hNIPK promoter. The coexpression of hNIPK inhibits activation of hNIPK promoter in response to the stress-inducing agents and to overexpressed ATF4, and thus NIPK may function as a negative feedback regulator of ATF4.",
Arsenic,1026103,"Combined effect of fluoride and arsenate on gene expression of osteoclast differentiation factor and osteoprotegerin Abstract: <strong>OBJECTIVE: </strong>To study the combined effect of fluoride and arsenate on the expression of SD rat osteoblastic osteoclast differentiation factor (ODF) mRNA and osteoprotegerin (OPG) mRNA.<br /><br /><strong>METHODS: </strong>Osteoblasts were obtained by enzymatic isolation from newborn SD rats. A factorial experiment was performed. Osteoblasts were exposed to NaF (0.5 mmolF/L, 4 molF/L) and Na3AsH2 (12.5 micromolAs/L and 200 micromolAs/L) separately or F plus As and cultured for 48 h. The gene expression of osteoblastic ODF and OPG was observed by RT-PCR.<br /><br /><strong>RESULTS: </strong>The expression of ODF mRNA increased in F0.5, F4 groups compared with control group and two groups of F0.5As200, F4As200 compared with As200 group, and decreased significantly in groups of F4Asl2.5, F0.5As200, and F4AS200. The expression of OPG mRNA decreased in groups of F4, As200, F4As12.5, F0.5AS200, and F4AS200.<br /><br /><strong>CONCLUSION: </strong>The joint effect of fluoride and arsenate on the gene expression of ODF is antagonistic, while the combined effect on the gene expression of OPG is synergistic. F4, F4As12.5, and F0.5As200 promote bone resorption of rat osteoclasts, whereas F0.5As12.5 inhibits osteolytic effect of rat osteoclasts.",
Arsenic,2345642,"A prospective analysis of airborne metal exposures and risk of Parkinson disease in the nurses health study cohort Abstract: <strong>BACKGROUND: </strong>Exposure to metals has been implicated in the pathogenesis of Parkinson disease (PD).<br /><br /><strong>OBJECTIVES: </strong>We sought to examine in a large prospective study of female nurses whether exposure to airborne metals was associated with risk of PD.<br /><br /><strong>METHODS: </strong>We linked the Environmental Protection Agency's Air Toxics tract-level data with the Nurses Health Study, a prospective cohort of female nurses. Over the course of 18 years of follow-up from 1990 to 2008, we identified 425 incident cases of PD. We examined the association of risk of PD with the following metals that were part of the first EPA collections in 1990, 1996, and 1999: arsenic, antimony, cadmium, chromium, lead, manganese, mercury and nickel, as well as total (sum) metal exposure. To estimate Hazard Ratios (HRs) and 95% confidence intervals (CI), we used the Cox Proportional Hazards model adjusting for age, smoking, and population density.<br /><br /><strong>RESULTS: </strong>In adjusted models, the HR for the highest compared with the lowest quartile of each metal ranged from 0.78 (95% CI: 0.59, 1.04) for chromium to 1.33 (95% CI: 0.98, 1.79) for mercury.<br /><br /><strong>CONCLUSIONS: </strong>Overall, we found limited evidence for the association between adulthood ambient exposure to metals and risk of PD. The results for mercury need to be confirmed in future studies.",
Arsenic,1340115,"Studying arsenite-humic acid complexation using size exclusion chromatography-inductively coupled plasma mass spectrometry Abstract: Arsenic (As) can form complexes with dissolved organic matter (DOM), which affects the fate of arsenic in waste sites and natural environments. It remains a challenge to analyze DOM-bound As, in particular by using a direct chromatographic separation method. Size exclusion chromatography (SEC) hyphenated with UV spectrophotometer and inductively coupled plasma mass spectrometry (ICP-MS) was developed to characterize the complexation of arsenite (As(III)) with DOM. This SEC-UV-ICP-MS method is able to differentiate As(III)-DOM complexes from free As species and has the advantage of direct determination of both free and DOM-bound As(III) through mild separation. The suitability of this method for studying As(III)-DOM complexation was demonstrated by its application, in combination with the Scatchard plot and nonlinear regression of ligand binding model, for characterizing As(III) complexation with humic acid (HA) in the absence or presence of natural sand. The results suggest that, consistent with polyelectrolytic nature of HA, the As(III)-HA complexation should be accounted for by multiple classes of binding sites. By loosely classifying the binding sites into strong (S1) and weak (S2) sites, the apparent stability constants (K(s)) of the resulting As-DOM complexes were calculated as logK(s1)=6.5-7.1 while logK(s2)=4.7-5.0.",
Arsenic,1797851,A luminescent-water soluble inorganic co-crystal for a selective pico-molar range arsenic(iii) sensor in water medium Abstract: The water solution of an intriguing luminescent 'Inorganic Co-crystal' of Cu(ii) monomeric and dimeric units shows extremely selective sensing ability towards inorganic arsenic(iii) in water medium in the pico-molar concentration range even in the presence of other cations.,
Arsenic,1025236,"Exogenous spermidine, arsenic and beta-aminobutyric acid modulate tobacco resistance to tobacco mosaic virus, and affect local and systemic glucosylsalicylic acid levels and arginine decarboxylase gene expression in tobacco leaves Abstract: The polyamine spermidine and the metalloid arsenic increased resistance responses in the well-known pathosystem NN tobacco/tobacco mosaic virus (TMV). Both the hypersensitive response to TMV in a leaf disk model system (inoculated disks floating in the 0.1mM treatments) and systemic acquired resistance (SAR) in whole plants were significantly affected. In the latter case, 1mM foliar sprays of spermidine and arsenic were as effective as TMV and dl-beta-aminobutyric acid (BABA), both taken as positive controls, in improving the plant's response to subsequent challenge inoculation with TMV. Moreover, this phenotypic response was correlated with changes in the endogenous concentration of the SAR-related molecule salicylic acid and in transcript levels of some pathogenesis/stress-related genes (pathogenesis-related proteins PR-1a and PR-2 and arginine decarboxylase (ADC)). Concentrations of free salicylic acid and of 2-O-beta-d-glucosylsalicylic acid and mRNA amount of PR-1a, PR-2 and ADC were analyzed in plants treated with either spermidine or arsenic, and compared with those from untreated plants and from positive (TMV-inoculated or BABA-treated) controls. Conjugated salicylic acid content and ADC transcripts were found to significantly increase, at both the local and systemic levels, relative to untreated controls.",
Arsenic,194133,"Genotoxic effects of environmental exposure to arsenic and lead on children in region Lagunera, Mexico Abstract: DNA damage and DNA repair ability by means of the comet assay and the hydrogen peroxide challenge in lymphocytes from 65 children exposed simultaneously to As and Pb in Region Lagunera, Mexico. The first exposure scenario was concerned with natural As contamination in drinking water affecting all children, particularly those attending the schools farthest from (Gomez Palacio) and closest to the smelter (Pedro Garcia). The second scenario related to additional Pb and As soil and dust contamination in the schools located in the smelter vicinity (Heroe de Nacozari and Pedro Garcia). Most children (93%) had As in urine (AsU) above 50 ?g/L and 65% had blood Pb (PbB) above 10 ?g/dL. The highest AsU median levels were observed in the school farthest from the smelter, whereas the highest PbB values were observed in the closest school. DNA damage and a decreased repair ability observed in children attending the schools were more severe than those reported for healthy Mexican children. However, the multivariate analysis did not show significant associations between DNA basal damage and PbB or AsU. Lymphocytes from 58% of the children did not respond to the peroxide challenge, and those had a more severe basal DNA damage. DNA repair capacity showed a slowed response and was negatively associated with AsU. Thus, in addition to reduced exposure, further studies are needed to ascertain if the deficiency in DNA repair is transient or if children are already displaying a mutator phenotype and are at risk of developing cancer.",
Arsenic,130559,"Arsenite binding to synthetic peptides based on the Zn finger region and the estrogen binding region of the human estrogen receptor-[alpha] Abstract: We selected the estrogen receptor protein for study because of prior results indicating that arsenite is a “potential nonsteroidal environmental estrogen”. We utilized radioactive 73As-labeled arsenite and vacuum filtration methodology to determine the binding affinity of arsenite to synthetic peptides. A zinc finger region containing four free sulfhydryls and the hormone binding region containing three free sulfhydryls based on the human estrogen receptor-? were studied. Peptide 15 (RYCAVCNDYASGYHYGVWSCEGCKA) bound arsenite with a Kd of 2.2 ?M and Bmax (maximal binding capacity) of 89 nmol/mg protein. Peptide 10 (LECAWQGKCVEGTEHLYSMKCKNV) had a Kd of 1.3 ?M and Bmax of 59 nmol/mg protein. In contrast, the monothiol peptide 19 (LEGAWQGKGVEGTEHLYSMKCKNV) bound arsenite with a higher Kd of 124 ?M and a Bmax of 26 nmol/mg protein. In our studies, amino acids other than cysteine (including methionine and histidine) did not bind arsenite at all. Peptides modeled on the estrogen receptor with two or more nearby free sulfhydryls (two or five intervening amino acids) had low Kd values in the 1–4 ?M range. Peptides containing single sulfhydryls or two sulfhydryls spaced 17 amino acids apart had higher Kd values in the 100–200 ?M range, demonstrating lower affinity. With the exception of peptide 24 which had an unusually high Bmax value of 234 nmol/mg, the binding capacity of the studied peptides was proportional to the number of free cysteines. Binding of trivalent arsenicals to peptides and proteins can contribute to arsenic toxicity and carcinogenicity via altered peptide/protein structure and enzyme function.",
Arsenic,1347905,"Mutation of a single conserved tryptophan in multidrug resistance protein 1 (MRP1/ABCC1) results in loss of drug resistance and selective loss of organic anion transport Abstract: Multidrug resistance protein 1 (MRP1/ABCC1) belongs to the ATP-binding cassette transporter superfamily and is capable of conferring resistance to a broad range of chemotherapeutic agents and transporting structurally diverse conjugated organic anions. In this study, we found that substitution of a highly conserved tryptophan at position 1246 with cysteine (W1246C-MRP1) in the putative last transmembrane segment (TM17) of MRP1 eliminated 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG) transport by membrane vesicles prepared from transiently transfected human embryonic kidney cells while leaving the capacity for leukotriene C(4)- and verapamil-stimulated glutathione transport intact. In addition, in contrast to wild-type MRP1, leukotriene C(4) transport by the W1246C-MRP1 protein was no longer inhibitable by E(2)17betaG, indicating that the mutant protein had lost the ability to bind the glucuronide. A similar phenotype was observed when Trp(1246) was replaced with Ala, Phe, and Tyr. Confocal microscopy of cells expressing Trp(1246) mutant MRP1 molecules fused at the C terminus with green fluorescent protein showed that they were correctly routed to the plasma membrane. In addition to the loss of E(2)17betaG transport, HeLa cells stably transfected with W1246C-MRP1 cDNA were not resistant to the Vinca alkaloid vincristine and accumulated levels of [(3)H]vincristine comparable to those in vector control-transfected cells. Cells expressing W1246C-MRP1 were also not resistant to cationic anthracyclines (doxorubicin, daunorubicin) or the electroneutral epipodophyllotoxin VP-16. In contrast, resistance to sodium arsenite was only partially diminished, and resistance to potassium antimony tartrate remained comparable to that of cells expressing wild-type MRP1. This suggests that the structural determinants required for transport of heavy metal oxyanions differ from those for chemotherapeutic agents. Our results provide the first example of a tryptophan residue being so critically important for substrate specificity in a eukaryotic ATP-binding cassette transporter.",
Arsenic,1337369,"A comparison of arsenic accumulation and tolerance among four populations of Pteris vittata from habitats with a gradient of arsenic concentration Abstract: Arsenic (As) contamination poses a high risk to human health. Phytoremediation based on As hyperaccumulator Pteris vittata has been utilized on large areas of contaminated farmland in southern China. However, the reason for the observed differences in As removal among P. vittata populations remains unclear. In this study, spores of four P. vittata populations were collected from four neighboring sites with varying soil As concentration (from 108mg·kg(-1) to 7527mg·kg(-1)) and then cultured in a controlled environment to analyze their differing abilities in terms of As accumulation and tolerance. The results indicate that populations from low-As habitats exhibited 80% greater shoot As concentrations compared with those from high-As habitats. On the other hand, populations from high-As habitats exhibited approximately five times greater biomass compared with those from low-As habitats when exposed to the same As stress. Thus, the As accumulation and tolerance of P. vittata were suggested to be two independent processes. Further investigations reveal that the As absorption and As species conversion occurring in roots are two essential activities that bridge the soil As concentration and the responses of P. vittata to As. Depending on the As concentration of the target soil, the selection of different P. vittata populations can result in approximately an eight-fold difference in terms of remediation efficiency.",
Arsenic,1797830,"Fat deposition in dilated cardiomyopathy assessed by CMR Abstract: <strong>OBJECTIVES: </strong>The aim of this study was to prospectively investigate the prevalence of fat deposition in idiopathic dilated cardiomyopathy (DCM) by fat-water separation imaging. An auxiliary aim was to determine the relationship between left ventricular (LV) fat deposition and characteristic myocardial fibrosis, as well as cardiac functional parameters.<br /><br /><strong>BACKGROUND: </strong>Idiopathic DCM remains the most common cause of heart failure in young people referred for cardiac transplantation; little is known about the clinical value of fat deposition in DCM.<br /><br /><strong>METHODS: </strong>A total of 124 patients with DCM were studied after written informed consent was obtained. The magnetic resonance imaging scan protocols included a series of short-axis LV cine imaging for functional analysis, fat-water separation imaging, and late gadolinium enhancement (LGE) imaging. Fat deposition and fibrosis location were compared to the scar regions on LGE images using a 17-segment model. Statistical comparisons of LV global functional parameters, fibrosis volumes, and fat deposition were carried out using the Pearson correlation, Student t test, and multiple regressions.<br /><br /><strong>RESULTS: </strong>The patients had a 41.9% (52 of 124) prevalence of positive LGE, and 12.9% (16 of 124) fat deposition prevalence was found in this DCM cohort. The patients with fat deposition had larger LV end-diastolic volume (LVEDV) index (140.8 ± 20.2 ml/m(2) vs. 123.4 ± 15.8 ml/m(2); p &lt; 0.01), larger LV end-systolic volume (LVESV) index (111.3 ± 19.2 vs. 87.0 ± 20.3 ml/m(2); p &lt; 0.01), and decreased LV ejection fraction (LVEF) (21.1 ± 7.1% vs. 30.0 ± 10.7%; p &lt; 0.01). Higher volumes of LGE were found in the group with myocardial fat deposition (18.39 ± 9.0 ml vs. 13.40 ± 6.54 ml; p = 0.001), as well as a higher percentage of LGE/LV mass (19.11 ± 7.78% vs. 13.60 ± 4.58%; p = 0.000). The volume of fat deposition was correlated with scar volume, LVEF, LVEDV index, and LVESV index.<br /><br /><strong>CONCLUSIONS: </strong>Fat deposition is a common phenomenon in DCM, and it is associated with DCM characteristics such as fibrosis volume and LV function.",
Arsenic,1016023,"High-resolution secondary ion mass spectrometry reveals the contrasting subcellular distribution of arsenic and silicon in rice roots Abstract: Rice (Oryza sativa) takes up arsenite mainly through the silicic acid transport pathway. Understanding the uptake and sequestration of arsenic (As) into the rice plant is important for developing strategies to reduce As concentration in rice grain. In this study, the cellular and subcellular distributions of As and silicon (Si) in rice roots were investigated using high-pressure freezing, high-resolution secondary ion mass spectrometry, and transmission electron microscopy. Rice plants, both the lsi2 mutant lacking the Si/arsenite efflux transporter Lsi2 and its wild-type cultivar, with or without an iron plaque, were treated with arsenate or arsenite. The formation of iron plaque on the root surface resulted in strong accumulation of As and phosphorous on the epidermis. The lsi2 mutant showed stronger As accumulation in the endodermal vacuoles, where the Lsi2 transporter is located in the plasma membranes, than the wild-type line. As also accumulated in the vacuoles of some xylem parenchyma cells and in some pericycle cells, particularly in the wild-type mature root zone. Vacuolar accumulation of As is associated with sulfur, suggesting that As may be stored as arsenite-phytochelatin complexes. Si was localized in the cell walls of the endodermal cells with little apparent effect of the Lsi2 mutation on its distribution. This study reveals the vacuolar sequestration of As in rice roots and contrasting patterns of As and Si subcellular localization, despite both being transported across the plasma membranes by the same transporters.",
Arsenic,710953,"Implementation of food frequency questionnaire for the assessment of total dietary arsenic intake in Bangladesh: part B, preliminary findings Abstract: Dietary intake of water and food has been identified as one of the major pathways for arsenic (As) exposure in the rural population of Bangladesh. Therefore, realistic assessment and measurement of dietary intake patterns are important for the development of an accurate estimate of As exposure and human health risk assessment. One important consideration is to identify an appropriate tool for measuring dietary intake. In this study an interviewer-administered Food Frequency Questionnaire (FFQ) was implemented to determine age and gender specific dietary intake. The developed FFQ was unique because it developed a synergy between field dietary assessment and As concentration measurements in various environmental media. The resulting integrated database provided an accurate framework for the process of As exposure and human health risk assessment. The preliminary results reported here from the FFQ demonstrated that this technique could be used in rural areas as a tool to assess As exposure and the associated human health risk.",
Arsenic,628611,"Toxicokinetic and genomic analysis of chronic arsenic exposure in multidrug-resistance mdr1a/1b(-/-) double knockout mice Abstract: Multidrug-resistance gene knockout mdr1a/1b(-/-) mice, which are deficient in P-glycoproteins, are more sensitive than wild-type (WT) mice to acute arsenic toxicity. This study assessed toxic manifestations of chronic oral arsenic in mdr1a/1b(-/-) mice, including oxidative stress and altered gene expression, and investigated altered toxicokinetics as a potential basis of enhanced arsenic toxicity. Thus, mdr1a/1b(-/-) and WT mice were exposed to sodium arsenite (0-80 ppm as arsenic) in the drinking water for 10 weeks at which time hepatic arsenic accumulation, lipid peroxidation (LPO), redox status and change in gene expression level were assessed. All mice survived the arsenic exposure, but body weight gain in the highest dose group was reduced in both mdr1a/1b(-/-) and WT mice. Arsenic induced pathological changes, elevated LPO levels and enhanced glutathione S-transferase (GST) activity, in the liver to a greater extent in mdr1a/1b(-/-) than in WT mice. Arsenic also decreased Cu/Zn superoxide dismutase activity in both mdr1a/1b(-/-) and WT mice. The expressions of certain genes, such as those encoding cell proliferation, GST, acute-phase proteins and metabolic enzymes, were modestly altered in arsenic-exposed mice. The expression of cyclin D1, a potential hepatic oncogene, was enhanced in arsenic-exposed mdr1a/1b(-/-) mice only. At the highest level of exposure, hepatic arsenic content was higher in mdr1a/1b(-/-) than in WT mice, suggesting that enhanced accumulation due to transport deficiency may, in part, account for the enhanced toxicity in these mice. In summary, this study shows that chronic arsenic toxicity, including liver pathology and oxidative stress, is enhanced in mdr1a/1b(-/-) mice, possibly due to enhanced accumulation of arsenic as a result of transport system deficiency.",
Arsenic,1677598,"In vitro intestinal bioavailability of arsenosugar metabolites and presystemic metabolism of thio-dimethylarsinic acid in Caco-2 cells Abstract: Whereas inorganic arsenic is classified as a human carcinogen, risks to human health related to the presence of arsenosugars in marine food are still unclear. Since studies indicate that human inorganic arsenic metabolites contribute to inorganic arsenic induced carcinogenicity, a risk assessment for arsenosugars should also include a toxicological characterization of their respective metabolites. Here we assessed intestinal bioavailability of the human arsenosugar metabolites oxo-DMAA(V), thio-DMAA(V), oxo-DMAE(V), thio-DMAE(V) and thio-DMA(V) in relation to arsenite in the Caco-2 intestinal barrier model. Whereas arsenite and thio-DMA(V) caused barrier disruption at concentrations ?10 ?M, all other metabolites did not cause a barrier leakage, even when applied at 50 times higher concentrations than arsenite and thio-DMA(V). The transfer studies point to a strong intestinal bioavailability of thio-DMA(V) and thio-DMAE(V), whereas oxo-DMAA(V), thio-DMAA(V) and oxo-DMAE(V) passed the in vitro intestinal barrier only to a very small extent. Detailed influx and efflux studies indicate that arsenite and thio-DMA(V) cross the intestinal barrier most likely by passive diffusion (paracellular) and facilitated (transcellular) transport. LC-ICP-QMS based arsenic speciation studies during the transfer experiments demonstrate transfer of thio-DMA(V) itself across the intestinal barrier and suggest metabolism of thio-DMA(V) using the in vitro intestinal barrier model to its oxygen-analogue DMA(V). In the case of arsenite no metabolism was observed. In summary the two arsenosugar metabolites thio-DMA(V) and thio-DMAE(V) showed intestinal bioavailability similar to that of arsenite, and about 10-fold higher than that reported for arsenosugars (Leffers et al., Mol. Nutr. Food Res., 2013, DOI: 10.1002/mnfr.201200821) in the same in vitro model. Thus, a presystemic metabolism of arsenosugars might strongly impact arsenic intestinal bioavailability after arsenosugar intake and should therefore be considered when assessing the risks to human health related to the consumption of arsenosugar-containing food.",
Arsenic,1337295,"Induction of apoptotic death and retardation of neuronal differentiation of human neural stem cells by sodium arsenite treatment Abstract: Chronic arsenic toxicity is a global health problem that affects more than 100 million people worldwide. Long-term health effects of inorganic sodium arsenite in drinking water may result in skin, lung and liver cancers and in severe neurological abnormalities. We investigated in the present study whether sodium arsenite affects signaling pathways that control cell survival, proliferation and neuronal differentiation of human neural stem cells (NSC). We demonstrated that the critical signaling pathway, which was suppressed by sodium arsenite in NSC, was the protective PI3K-AKT pathway. Sodium arsenite (2-4?M) also caused down-regulation of Nanog, one of the key transcription factors that control pluripotency and self-renewal of stem cells. Mitochondrial damage and cytochrome-c release induced by sodium arsenite exposure was followed by initiation of the mitochondrial apoptotic pathway in NSC. Beside caspase-9 and caspase-3 inhibitors, suppression of JNK activity decreased levels of arsenite-induced apoptosis in NSC. Neuronal differentiation of NSC was substantially inhibited by sodium arsenite exposure. Overactivation of JNK1 and ERK1/2 and down-regulation of PI3K-AKT activity induced by sodium arsenite were critical factors that strongly affected neuronal differentiation. In conclusion, sodium arsenite exposure of human NSC induces the mitochondrial apoptotic pathway, which is substantially accelerated due to the simultaneous suppression of PI3K-AKT. Sodium arsenite also negatively affects neuronal differentiation of NSC through overactivation of MEK-ERK and suppression of PI3K-AKT.",
Arsenic,1345929,"Nrf2 signaling, a mechanism for cellular stress resistance in long-lived mice Abstract: Transcriptional regulation of the antioxidant response element (ARE) by Nrf2 is important for the cellular adaptive response to toxic insults. New data show that primary skin-derived fibroblasts from the long-lived Snell dwarf mutant mouse, previously shown to be resistant to many toxic stresses, have elevated levels of Nrf2 and of multiple Nrf2-sensitive ARE genes. Dwarf-derived fibroblasts exhibit many of the traits associated with enhanced activity of Nrf2/ARE, including higher levels of glutathione and resistance to plasma membrane lipid peroxidation. Treatment of control cells with arsenite, an inducer of Nrf2 activity, increases their resistance to paraquat, hydrogen peroxide, cadmium, and UV light, rendering these cells as stress resistant as untreated cells from dwarf mice. Furthermore, mRNA levels for some Nrf2-sensitive genes are elevated in at least some tissues of Snell dwarf mice, suggesting that the phenotypes observed in culture may be mirrored in vivo. Augmented activity of Nrf2 and ARE-responsive genes may coordinate many of the stress resistance traits seen in cells from these long-lived mutant mice.",
Arsenic,2343511,"The Proteasome Inhibitor Bortezomib Is a Potent Inducer of Zinc Finger AN1-type Domain 2a Gene Expression: ROLE OF HEAT SHOCK FACTOR 1 (HSF1)-HEAT SHOCK FACTOR 2 (HSF2) HETEROCOMPLEXES Abstract: The zinc finger AN1-type domain 2a gene, also known as arsenite-inducible RNA-associated protein (AIRAP), was recently identified as a novel human canonical heat shock gene strictly controlled by heat shock factor (HSF) 1. Little is known about AIRAP gene regulation in human cells. Here we report that bortezomib, a proteasome inhibitor with anticancer and antiangiogenic properties used in the clinic for treatment of multiple myeloma, is a potent inducer of AIRAP expression in human cells. Using endothelial cells as a model, we unraveled the molecular mechanism regulating AIRAP expression during proteasome inhibition. Bortezomib induces AIRAP expression at the transcriptional level early after treatment, concomitantly with polyubiquitinated protein accumulation and HSF activation. AIRAP protein is detected at high levels for at least 48 h after bortezomib exposure, together with the accumulation of HSF2, a factor implicated in differentiation and development regulation. Different from heat-mediated induction, in bortezomib-treated cells, HSF1 and HSF2 interact directly, forming HSF1-HSF2 heterotrimeric complexes recruited to a specific heat shock element in the AIRAP promoter. Interestingly, whereas HSF1 has been confirmed to be critical for AIRAP gene transcription, HSF2 was found to negatively regulate AIRAP expression after bortezomib treatment, further emphasizing an important modulatory role of this transcription factor under stress conditions. AIRAP function is still not defined. However, the fact that AIRAP is expressed abundantly in primary human cells at bortezomib concentrations comparable with plasma levels in treated patients suggests that AIRAP may participate in the regulatory network controlling proteotoxic stress during bortezomib treatment.",
Arsenic,1019269,"Systemic indicators of inorganic arsenic toxicity in four animal species Abstract: The effect of arsenic compounds depends on the chemical form and is specific for certain organs. The lack of specific biological indicators for the effects of each arsenic species makes it difficult to differentiate their toxicity. Five prospective biological indicators of systemic toxicity were examined at time points ranging from 15 min to 24 h using male Sprague-Dawley rats, B6C3F1 mice, Golden-Syrian hamsters, and Hartley guinea pigs, following intraperitoneal dosing with 0.1 and 1 mg/kg sodium arsenite. Rats and mice were also dosed with 1 mg/kg sodium arsenate. Total blood arsenic levels were determined in all animal species to show that exposure occurred and as an index of the severity of the change is an indicator of toxicity. Total blood arsenic levels were increased in all animal species. This increase was dose, arsenic species, and animal dependent. Renal pyruvate dehydrogenase activity was significantly decreased at early time points in mice, hamsters, and guinea pigs, and at later time points in rats dosed with arsenite. Rats and mice dosed with arsenate also exhibited PDH decrease at early time points. Blood hematocrit and glucose were increased in the rat and guinea pig, respectively, after arsenite administration. Creatinine and urea nitrogen were found to be unresponsive to arsenic in most animal species. Data suggested that the mouse and secondly the hamster appear to be the most appropriate animal models for the study of acute arsenic toxicity.",
Arsenic,613011,"Effect of Selenium and Vitamin E Supplementation on Plasma Protein Carbonyl Levels in Patients With Arsenic-Related Skin Lesions Abstract: An estimated 35 million people in Bangladesh have been chronically exposed to arsenic in drinking water and are at risk of an array of adverse health conditions. The mechanisms of arsenic toxicity have not been well established; however, oxidative stress has been one commonly proposed pathway. In this study, we evaluated the effect of antioxidant supplementation on plasma protein oxidation among patients with arsenical skin lesions participating in a randomized double-blinded placebo-controlled trial of vitamin E and selenium. Subjects were randomized to 1 of 4 treatments arms (vitamin E, selenium, combination, or placebo) and were treated for a 6-mo period. We observed a dose-dependent increase in adjusted protein carbonyl levels by arsenic exposure status in the pretreatment samples, although trends were not statistically significant. Following the 6-mo intervention, there was a decrease in protein carbonyl levels in each treatment group, although no resultant decrease was significantly different from that seen in the placebo group. Although we did not see a notable effect of selenium or vitamin E supplementation on changes in protein carbonyl levels, these preliminary data demonstrate a feasible methodological approach for the assessment of plasma protein carbonyls in relation to environmental toxicants in a human population and their potential use as endpoints in intervention trials. [ABSTRACT FROM AUTHOR] Copyright of Nutrition & Cancer is the property of Lawrence Erlbaum Associates and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1025124,"An exposure and risk assessment for fluoride and trace metals in black tea Abstract: Exposure and associated health risks for fluoride and trace metals in black tea were estimated. Fifty participants were randomly recruited to supply samples from the tea that they drink, and self-administer a questionnaire that inquired about personal characteristics and daily tea intake. Analyzed trace metals included aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, manganese, nickel, strontium, and zinc. Fluoride and four metals (Al, Cr, Mn, Ni) were detected in all samples while barium was detected only in one sample. The remaining metals were detected in &gt;60% of the samples. Fluoride and aluminum levels in instant tea bag samples were greater than in loose tea samples (p&lt;0.05) while the differences in elemental concentrations of loose and pot bag tea samples were not significant. Median and 90th percentile daily tea intake rates were estimated as 0.35 and 1.1l/day, respectively. Neither fluoride nor aluminum levels in black tea were found to associate with considerable risks of fluorosis and Alzheimer's disease, respectively. However, carcinogenic risk levels for arsenic were high; R&gt;1.0 x 10(-6) even at the median level. According to sensitivity analysis, daily tea intake was the most influencing variable to the risk except for arsenic for which the concentration distribution was of more importance.",
Arsenic,1015822,"Effect of bacterial mineralization of phytoplankton-derived phytodetritus on the release of arsenic, cobalt and manganese from muddy sediments in the Southern North Sea. A microcosm study Abstract: Muddy sediments of the Belgian Continental Zone (BCZ) are contaminated by metals such as Co, As, Cd, Pb, and Ni. Previous studies have suggested that mineralization of phytodetritus accumulating each year on sediments might cause secondary contaminations of the overlying seawater (metal effluxes). The aim of the present research was to investigate these effluxes using a microcosm approach. Muddy sediments were placed in microcosms (diameter: 15 cm) and overlaid by phytodetritus (a mix of Phaeocystis globosa with the diatom Skeletonema costatum). The final suspension was 130.6 mg L(-1) (dw) and the final chlorophyll a content was 750 ± 35?gL(-1) (mean ± SD). Natural seawater was used for controls. Microcosms were then incubated in the dark at 15°C during 7 days. Metals were monitored in overlying waters and microbial communities were followed using bacterial and nanoflagellate DAPI counts, thymidine incorporation, community level physiological profiling (CLPP) and fluorescein diacetate analysis (FDA). Benthic effluxes observed in sediments exposed to phytodetritus were always more elevated than those observed in controls. Large effluxes were observed for Mn, Co and As, reaching 1084 nmolm(-2)day(-1) (As), 512 nmolm(-2)day(-1) (Co), and 755 ?molm(-2)day(-1) (Mn). A clear link was established between heterotrophic microbial activity and metal effluxes. The onset of mineralization was very fast and started within 2 h of deposition as revealed by CLPP. An increased bacterial production was observed after two days (8.7mgCm(-2)day(-2)) and the bacterial biomass appeared controlled by heterotrophic nanoflagellates. Calculations suggest that during phytoplankton blooms the microbial activity alone may release substantial amounts of dissolved arsenic in areas of the BCZ covered by muddy sediments.",
Arsenic,1519051,"Uncoupling RARA transcriptional activation and degradation clarifies the bases for APL response to therapies Abstract: In PML/RARA-driven acute promyelocytic leukemia (APL), retinoic acid (RA) induces leukemia cell differentiation and transiently clears the disease. Molecularly, RA activates PML/RARA-dependent transcription and also initiates its proteasome-mediated degradation. In contrast, arsenic, the other potent anti-APL therapy, only induces PML/RARA degradation by specifically targeting its PML moiety. The respective contributions of RA-triggered transcriptional activation and proteolysis to clinical response remain disputed. Here, we identify synthetic retinoids that potently activate RARA- or PML/RARA-dependent transcription, but fail to down-regulate RARA or PML/RARA protein levels. Similar to RA, these uncoupled retinoids elicit terminal differentiation, but unexpectedly fail to impair leukemia-initiating activity of PML/RARA-transformed cells ex vivo or in vivo. Accordingly, the survival benefit conferred by uncoupled retinoids in APL mice is dramatically lower than the one provided by RA. Differentiated APL blasts sorted from uncoupled retinoid-treated mice retain PML/RARA expression and reinitiate APL in secondary transplants. Thus, differentiation is insufficient for APL eradication, whereas PML/RARA loss is essential. These observations unify the modes of action of RA and arsenic and shed light on the potency of their combination in mice or patients.",
Arsenic,1016328,"Integrating phenotypic and expression profiles to map arsenic-response networks Abstract: <strong>BACKGROUND: </strong>Arsenic is a nonmutagenic carcinogen affecting millions of people. The cellular impact of this metalloid in Saccharomyces cerevisiae was determined by profiling global gene expression and sensitivity phenotypes. These data were then mapped to a metabolic network composed of all known biochemical reactions in yeast, as well as the yeast network of 20,985 protein-protein/protein-DNA interactions.<br /><br /><strong>RESULTS: </strong>While the expression data unveiled no significant nodes in the metabolic network, the regulatory network revealed several important nodes as centers of arsenic-induced activity. The highest-scoring proteins included Fhl1, Msn2, Msn4, Yap1, Cad1 (Yap2), Pre1, Hsf1 and Met31. Contrary to the gene-expression analyses, the phenotypic-profiling data mapped to the metabolic network. The two significant metabolic networks unveiled were shikimate, and serine, threonine and glutamate biosynthesis. We also carried out transcriptional profiling of specific deletion strains, confirming that the transcription factors Yap1, Arr1 (Yap8), and Rpn4 strongly mediate the cell's adaptation to arsenic-induced stress but that Cad1 has negligible impact.<br /><br /><strong>CONCLUSIONS: </strong>By integrating phenotypic and transcriptional profiling and mapping the data onto the metabolic and regulatory networks, we have shown that arsenic is likely to channel sulfur into glutathione for detoxification, leads to indirect oxidative stress by depleting glutathione pools, and alters protein turnover via arsenation of sulfhydryl groups on proteins. Furthermore, we show that phenotypically sensitive pathways are upstream of differentially expressed ones, indicating that transcriptional and phenotypic profiling implicate distinct, but related, pathways.",
Arsenic,2298688,"The efficacy and morbidity of different surgical treatment techniques for chronic anal fissure: an academic colorectal experience Abstract: Up to 40 per cent of chronic fissures will fail to heal with medical treatment alone. Open (OLIS) and closed (CLIS) lateral internal sphincterotomies are considered by many to be the treatment of choice for chronic anal fissures (CAF). The aim of this study was to compare the efficacy and clinical outcomes of different surgical techniques for treatment of CAF. We performed a retrospective chart review of 387 patients with CAF who underwent surgical intervention performed by colorectal surgeons between 2006 and 2012 at Greenville Hospital System. Of 387 patients, 199 underwent OLIS, 124 CLIS, and 64 patients underwent fissurectomy alone (FE). We investigated the effect of the surgical technique on time of healing, rate of flatus incontinence, wound infection, recurrence, and the need for additional intervention. There was no statistically significant difference among patients undergoing OLIS, CLIS, and FE in demographic characteristic, time of healing, rate of wound infections, and fecal continence, or recurrence rate. Comparison of a combined lateral internal sphincterotomy (LIS) group with FE showed that there is similar time of healing (P = 0.58), no statistical difference in flatus incontinence rate (P = 0.61), urinary retention (P = 1.0), fissure recurrence (P = 0.11), and prolonged healing (P = 0.2). Patients in FE group more likely required additional treatment to complete wound healing (P = 0.02). LIS is a safe and effective technique for treatment of CAF. Although there was no difference in complications rate and healing time, patients in the FE group required additional surgical or medical treatment more frequently to achieve complete healing.",
Arsenic,1339960,"Concentrations and geographical variations of selected toxic elements in meat from semi-domesticated reindeer (Rangifer tarandus tarandus L.) in mid- and northern Norway: Evaluation of risk assessment Abstract: Meat samples (n = 100) from semi-domesticated reindeer (Rangifer tarandus tarandus L.) were randomly collected from 10 grazing districts distributed over four Norwegian counties in 2008 and 2009. The main aim was to study concentrations and geographical variations in selected toxic elements; cadmium (Cd), lead (Pb), arsenic (As), copper (Cu), nickel (Ni) and vanadium (V) in order to assess the risk associated with reindeer meat consumption. Sample solutions were analysed using an inductively coupled plasma high resolution mass spectrometer (ICP-HRMS), whereas analysis of variance (ANOVA) was used for statistical analyses. Geographical variations in element concentrations were revealed, with As and Cd demonstrating the largest geographical differences. No clear geographical gradient was observed except for the east-west downward gradient for As. The As concentrations were highest in the vicinity of the Russian border, and only Cd was shown to increase with age (p &lt; 0.05). Sex had no significant effect on the concentration of the studied elements. The concentrations of all the studied elements in reindeer meat were generally low and considerably below the maximum levels (ML) available for toxic elements set by the European Commission (EC). Thus, reindeer meat is not likely to be a significant contributor to the human body burden of toxic elements.",
Arsenic,1342527,"Arsenite alters heme synthesis in long-term cultures of adult rat hepatocytes Abstract: Arsenite (As[III]) effects on the intermediate steps of heme biosynthesis were studied in adult rat hepatocytes seeded on a feeder layer of 3T3 cells (3T3-hepatocytes) and maintained for 2 weeks with culture medium non-supplemented or supplemented with 150 microM 5-aminolevulinic acid (ALA). The activities of the intracellular enzymes porphobilinogen deaminase (PBG-D), uroporphyrinogen III synthase (UROIII-S), and uroporphyrinogen III decarboxylase (URO-D), and the intermediary uroporphyrins (URO), coproporphyrins (COPRO) and protoporphyrin IX (PROTO) were determined in these cultures. The 3T3-hepatocytes maintained the activities of PBG-D, UROIII-S and URO-D during 2 weeks and ALA addition to the culture medium increased PBG-D (2-3-fold) and UROIII-S (50%) activities and porphyrin production, which accumulated as PROTO. Exposure to 3.9 microM As(III) inhibited UROIII-S activity (down to 34%), and PBG-D and URO-D activities to a lower extent; these effects were magnified by ALA supplementation. As(III) also produced an intracellular accumulation and a decreased excretion of PROTO, and a 31% reduction of the COPRO/URO ratio in the culture medium. Additionally, As(III) caused cytoplasmic vacuolization and lipid accumulation. Our results show that As(III) exposure selectively inhibits several intermediary enzymes of heme metabolism and affects the intra- and extracellular content of porphyrins and their ratio in the culture medium. They also confirm that 3T3-hepatocytes are a suitable in vitro model to study hepatic heme metabolism and its alterations by hepatotoxic chemicals.",
Arsenic,627653,"Arsenite delays progression through each cell cycle phase and induces apoptosis following G2/M arrest in U937 myeloid leukemia cells Abstract: Arsenic is a well known toxicant and carcinogen that is also effective as a chemotherapeutic in the treatment of acute promyelocytic leukemia. Although its effects on humans are well documented, arsenic's mechanism of action is not well understood. Its ability to act as a carcinogen and as a chemotherapeutic seems paradoxical. However, cancer cell transformation and cancer cell destruction can both occur through perturbations of the cell cycle machinery, making cell cycle function a likely target of arsenic action. Arsenic has previously been shown to inhibit cancer cell cycle progression, but the targeted cell cycle phase has been debated. This study was designed to identify the cell cycle phase at which U937 cells are most sensitive to arsenite-induced growth inhibition. Centrifugal elutriation was used to divide asynchronous cell cultures into specific cell cycle phase-enriched fractions. These fractions were monitored for cell cycle phase progression in the presence and absence of sodium arsenite. We found an overall reduction in cell cycle progression rather than induction of arrest at one specific checkpoint. G(2)/M is the phase most sensitive to arsenite-induced apoptosis. However, arsenite profoundly affects U937 cell growth by increasing the length of time it takes cells to transit each phase of the cell cycle. Future study of cell cycle inhibition by arsenic should consider that the effect may not be mediated by the major cell cycle checkpoints. Arsenic's ability to inhibit growth in any cell cycle phase may increase its value as a chemotherapeutic used together with other, more phase-selective agents, such as camptothecin.",
Arsenic,1337911,"Arsenic species in broiler (Gallus gallus domesticus) litter, soils, maize (Zea mays L.), and groundwater from litter-amended fields Abstract: Manure and bedding material (litter) generated by the broiler industry (Gallus gallus domesticus) often contain high levels of arsenic (As) when organoarsenical roxarsone and p-arsanilic acid are included in feed to combat disease and improve weight gain of the birds. This study was conducted to determine As levels and species in litter from three major broiler producing companies, and As levels in soils, corn tissue (Zea mays L.), and groundwater in fields where litter was applied. Total As in litter from the three different integrators ranged between &lt;1 and 44mgkg(-1). Between 15 and 20% of total As in litter consisted of mostly of arsenate, with smaller amounts of roxarsone and several transformation products that were extractable with phosphate buffer. Soils amended with litter had higher levels of bioavailable As (extractable with Mehlich 3 solution and taken up by corn leaves). Arsenic concentrations in plant tissue and groundwater, however, were below the World Health Organization thresholds, which was attributed to strong sorption/precipitation of arsenate in Fe- and Al-rich soils. Ecological impacts of amending soils with As-laden litter depend on the As species in the litter, and chemical and physical properties of soil that strongly affect As mobility and bioavailability in the environment.",
Arsenic,20366,Inducibility of sister-chromatid exchanges by heavy-metal ions Abstract: HEEP COPYRIGHT: BIOL ABS. CHINESE HAMSTER LUNG DON CELL CHROMIUM IRON NICKEL SELENIUM CADMIUM MERCURY ARSENIC TITANIUM ZIRCONIUM TIN CARCINOGENICITY,
Arsenic,1936136,"Clonal variation in growth, arsenic and heavy metal uptakes of hybrid Eucalyptus clones in a Mediterranean environment Abstract: Variation in growth, arsenic and heavy metal uptakes by aboveground tissues (leaves, stems and branches) of 13 hybrid Eucalyptus clones selected for biomass production in a Mediterranean environment (E. camaldulensis × E. viminalis; E. camaldulesis × E. grandis; E. camaldulensis × E. globulus subsp. bicostata) was investigated on agricultural soils field-contaminated with arsenic (As), cadmium (Cd), chrome (Cr), lead (Pb), copper (Cu) and zinc (Zn) in an ex situ nursery experiment in central Italy. Large variation in growth and contaminant uptake amongst the tested clones was observed. All plants survived and 12 clones grew better than the control (E. camaldulensis). All clones accumulated the contaminants to which they were exposed: As, Cu, Pb and Zn concentrations were significantly higher in leaves than in stems and branches, supporting the potential for phytoremediation of these contaminants by Eucalyptus short rotation woody crops (SRWC). Significant positive correlations between the average contents of Cd–Pb, Cd–Cu, Cd–Zn, Pb–Cu, Pb–Zn and Cu–Zn in the aboveground tissues were detected. Clones revealed better phytoextraction performance than that of the control. Four promising clones for biomass production and phytoremediation were identified for prospective use in SRWC on contaminated soils in Mediterranean environments.",
Arsenic,47166,"Heavy metals in human hair samples from Austria and Italy: Influence of sex and smoking habits Abstract: Hair samples from 79 young healthy adults from Vienna (Austria) and Rome (Italy) were analyzed for As, Cd, Co, Cr, Ni and Pb by ICP-MS. No differences were found between the two locations except for chromium, which was significantly higher in the Viennese population (P &lt; 0.001). In both cities male hair contained higher arsenic (P &lt; 0.001) and lower cadmium (P &lt; 0.05) levels than female hair, and in Vienna lead concentrations were lower in males (P &lt; 0.05). Striking differences appeared when smokers were compared with non-smokers. Geometric means (micrograms/g) of smokers versus non-smokers were: arsenic 0.081 vs. 0.065, cadmium 0.075 vs. 0.038 (P &lt; 0.05), cobalt 0.025 vs. 0.010 (P &lt; 0.05), chromium 0.84 vs. 0.72 (P &lt; 0.05), lead 3.42 vs. 1.47 (P &lt; 0.001) and nickel 0.64 vs. 0.32 (P &lt; 0.005). Consideration of a large number of biological and behavioural factors minimizes bias inherent in unmatched sample composition.",
Arsenic,1026744,"Mortality in a cohort of pesticide applicators in an urban setting: Sixty years of follow-up Abstract: The study is a further follow-up of a cohort of 168 urban pesticide applicators of the municipality of Rome who were first employed in 1946. An earlier analysis of the mortality of this group concerned the deaths observed up to 1987, and showed a significant excess in mortality from liver cancer. In this report we present an updated follow up of the mortality of the cohort, which comprises the total of 85 deaths for the entire period of observation, corresponding to 5227 person/years. The living status of each member of the cohort was ascertained through the official records up to 2005. For the 85 deceased individuals, the primary cause of death was coded according to the 9th Revision of the ICD. Standardized mortality ratios (SMR) were calculated on the basis of the age, sex, and cause specific mortality rates prevailing during the same calendar years in the province of Rome. The SMR from all causes for the whole cohort was 103.8 (90 %CI 86 124). The SMR for all cancers was 106.0 ( 90 % CI 75-146). An increased risk was observed for the exposed for cancer of the gallbladder (SMR 723.8 90% CI 129-2279), of the liver (SMR 596.3, 90 % CI 204-1365) and for cancer of the nervous system (SMR 529.2, 90 % CI 144-1368). All increases were statistically significant, but no association was found between the increased risk of these cancers and the longer duration of exposure. The increase in risk of the three cancers mentioned above (liver, nervous system and gallbladder), was further increased, when the analysis was restricted to the workers exposed prior to the 1978 ban of DDT and products containing arsenic.",
Arsenic,1936053,"Preference for subcutaneous or intravenous administration of trastuzumab in patients with HER2-positive early breast cancer (PrefHer): an open-label randomised study Abstract: Background: Subcutaneous trastuzumab has shown non-inferior efficacy and a similar pharmacokinetic and safety profile when compared with intravenous trastuzumab in patients with HER2-positive early breast cancer. We assessed patient preference for either subcutaneous or intravenous trastuzumab in the international, randomised PrefHer study. Methods: Eligible patients were women aged 18 years or older with HER2-positive, histologically confirmed primary invasive breast adenocarcinoma, no evidence of residual, locally recurrent, or metastatic disease after completion of surgery and chemotherapy (neoadjuvant or adjuvant), an Eastern Cooperative Oncology Group performance status of 0 or 1, and a baseline left-ventricular ejection fraction of 55% or more before the first dose of trastuzumab. Radiotherapy or hormone therapy was allowed. Patients were randomised (randomly permuted blocks of four) to receive four cycles of 600 mg fixed-dose subcutaneous adjuvant trastuzumab via a single-use injection device or hand-held syringe followed by four cycles of standard intravenous trastuzumab, or the reverse sequence. Randomisation was stratified by de-novo versus non-de-novo use of intravenous trastuzumab. The primary endpoint was the proportion of patients indicating an overall preference for subcutaneous or intravenous trastuzumab, assessed by patient interview in the evaluable intention-to-treat (ITT) population (patients who completed both interviews and had at least one administration of both subcutaneous and intravenous trastuzumab). Data collection for PrefHer is ongoing. This study is registered with ClinicalTrials.gov, number NCT01401166. Findings: 124 patients were randomly allocated to receive subcutaneous followed by intravenous trastuzumab, and 124 to receive the reverse sequence. 117 patients in the subcutaneous first group and 119 in the intravenous first group were included in the evaluable ITT population. Subcutaneous trastuzumab via the single-use injection device was preferred by 216 patients (91·5%, 95% CI 87·2–94·7; p<0·0001). Only 16 patients preferred intravenous trastuzumab (6·8%, 3·9–10·8), and four had no preference (1·7%, 0·5–4·3). Clinician-reported adverse events occurred in 141 of 242 (58%) patients during the pooled subcutaneous periods and 105 of 241 (44%) patients during the pooled intravenous periods; seven (3%) and five (2%) were grade 3, no patients had a grade 4 or 5 event. The most common grade 3 adverse event was influenza (two [0·8%] patients). Interpretation: Patient preference and safety results from PrefHer, combined with the known non-inferior efficacy and pharmacokinetic and safety profile data, suggest that a fixed dose of 600 mg trastuzumab administered subcutaneously every 3 weeks is a validated, well tolerated treatment option for HER2-positive breast cancer, and is the preferred treatment of patients. Funding: Hoffmann-La Roche.",
Arsenic,735172,"Modulatory effects of ascorbic acid and alpha-tocopherol on arsenic induced micronuclei formation Abstract: Arsenic is a well known human carcinogen and has many other toxic effects. Sodium arsenite, a compound of arsenic, capable of inducing genotoxic effects through oxidative stress, is evaluated for its genotoxic effect by the formation of micronuclei in the polychromatic erythrocytes in the bone marrow cells of Wistar rats. Further, the modulatory effects of antioxidants like ascorbic acid and alpha-tocopherol on arsenic intoxicated rats is investigated. Therefore, the present study was designed to determine whether the oral supplementation of alpha-tocopherol (400 mg kg(-1) body weight) and ascorbic acid (200 mg kg(-1) b.wt.) to arsenic-intoxicated rats (100 ppm in drinking water) for 30 days, modulates the genotoxicity caused by arsenic through the formation of micronuclei (p<0.05). The findings suggest that co-treatment of ascorbic acid and alpha-tocopherol to arsenic-exposed rats protects the antioxidant system and modulates arsenic induced micronuclei formation.",
Arsenic,1579240,"p27 Suppresses cyclooxygenase-2 expression by inhibiting p38? and p38?-mediated CREB phosphorylation upon arsenite exposure Abstract: p27 is a cyclin-dependent kinase (CDK) inhibitor that suppresses a cell's transition from G0 to S phase, therefore acting as a tumor suppressor. Our most recent studies demonstrate that upon arsenite exposure, p27 suppresses Hsp27 and Hsp70 expressions through the JNK2/c-Jun- and HSF-1-dependent pathways, suggesting a novel molecular mechanism underlying the tumor suppressive function of p27 in a CDK-independent manner. We found that p27-deficiency (p27-/-) resulted in the elevation of cyclooxygenase-2 (COX-2) expression at transcriptional level, whereas the introduction of p27 brought back COX-2 expression to a level similar to that of p27+/+ cells, suggesting that p27 exhibits an inhibitory effect on COX-2 expression. Further studies identified that p27 inhibition of COX-2 expression was specifically due to phosphorylation of transcription factor cAMP response element binding (CREB) phosphorylation mediated by p38? and p38?. These results demonstrate a novel mechanism underlying tumor suppression effect of p27 and will contribute to understanding of the overall mechanism of p27 tumor suppression in a CDK-independent manner.",
Arsenic,710991,"Mitigation of arsenic-mediated renal oxidative stress in rat by Pleurotus florida lectin Abstract: Oyster mushroom, Pleurotus florida is regarded as one of the popular food with biopharmaceutical properties. Here, the study aimed to investigate the antioxidative effects of mushroom (Pleurotus florida) lectin against arsenic-induced nephrotoxicity in rats. Animals were divided into four groups; Group 1 was control. Groups 2, 3 and 4 were exposed to arsenic (20 parts per million [ppm] in drinking water), arsenic plus oral supplementation of ascorbic acid (25 mg/kg body weight) and arsenic plus oral supplementation of mushroom lectin (150 mg/kg body weight) respectively. Both ascorbic acid and mushroom lectin prevented the arsenic-mediated growth retardation and normalized the elevated kidney weight. Disrupted activities of superoxide dismutase (SOD) and catalase (CAT) and enhanced lipid peroxidation (LPO), protein carbonyl (PC) and nitric oxides (NO) production in kidney caused by arsenic could also be maintained towards normalcy by supplementation of mushroom lectin and ascorbic acid. These antioxidative effects were exhibited in a time-dependant manner. Further, arsenic-mediated down-regulation of messenger RNA (mRNA) expression of superoxide dismutase 2 (SOD(2) ) gene was obstructed by these agents. Thus it was found that mushroom lectin reversed the effect of arsenic-mediated oxidative stress in a time-dependent manner.",
Arsenic,1016655,"Multi-component assessment of worker exposures in a copper refinery. Part 1. Environmental monitoring Abstract: The exposure characterisation described in this paper for 135 copper refinery workers (45 females, 90 males) focuses on the concentrations of copper, nickel and other trace elements in the inhalable aerosol fractions, as well as in the water-soluble and water-insoluble subfractions. Some information is also provided on the thoracic and respirable aerosol fractions. Further, results are presented for volatile hydrides of arsenic and selenium released in the copper purification steps of the electrorefining process. For the pyrometallurgical operations, a comparison of the geometric means for the inhalable aerosol fraction indicated that water-soluble copper levels were on average 19-fold higher compared to nickel (p &lt; 0.001) and a significant association was evident between them (r = 0.87, p &lt; 0.001); for the insoluble subfraction, the copper : nickel ratio was 12.5 (p &lt; 0.001) and the inter-element correlation had r = 0.98 and p &lt; 0.001. Although for the electrorefinery workers the relative inhalable concentrations of copper and nickel were not significantly different (p &gt; 0.05), the corresponding inter-element associations were: slope of 7.7, r= 0.54, p &lt; or =0.001 for the water-soluble subfraction and slope of 1.3, r = 0.71 and p &lt; or =0.001 for the water-insoluble subfraction. On average, a good proportion of the inhalable copper and nickel were found in the thoracic (40%) and respirable (20%) aerosol fractions. Cobalt air concentrations were generally low with geometric means and 95% confidence intervals of 3.1 (2.4-4.2)microg m(-3) (pyrometallurgical workers) and 0.3 (0.4-0.5) microg m(-3)(electrorefinery workers). Similarly, the maximum concentrations of cadmium and lead were low, respectively 4 and 25 microg m(-3). Of the hydrides, tellurium and antimony could not be detected, but for the arsenic (arsine) and selenium hydrides measurable exposure occurred for almost all electrorefinery workers, although the levels were generally low at 0.2 microg m(-3).",
Arsenic,2088330,"Bayesian spatial design of optimal deep tube well locations in Matlab, Bangladesh Abstract: ",
Arsenic,2337197,"Association between risk of birth defects occurring level and arsenic concentrations in soils of Lvliang, Shanxi province of China Abstract: The risk of birth defects is generally accredited with genetic factors, environmental causes, but the contribution of environmental factors to birth defects is still inconclusive. With the hypothesis of associations of geochemical features distribution and birth defects risk, we collected birth records and measured the chemical components in soil samples from a high prevalence area of birth defects in Shanxi province, China. The relative risk levels among villages were estimated with conditional spatial autoregressive model and the relationships between the risk levels of the villages and the 15 types of chemical elements concentration in the cropland and woodland soils were explored. The results revealed that the arsenic levels in cropland soil showed a significant association with birth defects occurring risk in this area, which is consistent with existing evidences of arsenic as a teratogen and warrants further investigation on arsenic exposure routine to birth defect occurring risk.",
Arsenic,2225067,"Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2 Abstract: Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 ?g L(-1) Cr(VI) and the limit of detection was found to be 6.6 ?g L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity.",
Arsenic,2345616,"Arsenic induces sustained impairment of skeletal muscle and muscle progenitor cell ultrastructure and bioenergetics Abstract: Over 4 million individuals in the US, and over 140 million individuals worldwide, are exposed daily to arsenic-contaminated drinking water. Human exposures can range from below the current limit of 10?g/L to over 1mg/L, with 100?g/L promoting disease in a large portion of those exposed. Although increased attention has recently been paid to myopathy following arsenic exposure, the pathogenic mechanisms underlying clinical symptoms remain poorly understood. This study tested the hypothesis that arsenic induces lasting muscle mitochondrial dysfunction and impairs metabolism. When compared to non-exposed controls, mice exposed to drinking water containing 100?g/L arsenite for 5 weeks demonstrated impaired muscle function, mitochondrial myopathy, and altered oxygen consumption that were concomitant with increased mitochondrial fusion gene transcription. There was no difference in levels of inorganic arsenic or its mononomethyl- and dimethyl- metabolites between controls and exposed muscles, confirming that arsenic does not accumulate in muscle. Nevertheless, muscle progenitor cells isolated from exposed mice recapitulated the aberrant myofiber phenotype and were more resistant to oxidative stress, generated more reactive oxygen species, and displayed autophagic mitochondrial morphology, as compared to cells isolated from non-exposed mice. These pathological changes from a possible maladaptive oxidative stress response provide insight into declines in muscle functioning caused by exposure to this common environmental contaminant.",
Arsenic,632837,"Arsenite decreases CYP3A4 and RXRalpha in primary human hepatocytes Abstract: Arsenic is a naturally occurring, worldwide contaminant implicated in numerous pathological conditions in humans, including cancer and several forms of liver disease. One of the contributing factors to these disorders may be the alteration of cytochrome P450 (P450) levels by arsenic. P450s are involved in the oxidative metabolism and elimination of numerous toxic chemicals. CYP3A4, a major P450 in humans, is involved in the metabolism of half of all currently used drugs. Acute exposure to arsenite decreases the induction of CYP1A1/2 proteins and activities in cultured human hepatocytes, as well as CYP3A23 in cultured rat hepatocytes. Here, in primary cultures of human hepatocytes, we assessed the effects of acute arsenite exposure on CYP3A4 and several transcription factors involved in CYP3A4 expression. The concentrations of arsenite used in these studies were nontoxic to the hepatocytes and failed to elicit an oxidative response. Treatment with arsenite in the presence of CYP3A4 inducers, rifampicin (Rif) or phenobarbital, caused major decreases in CYP3A4 mRNA, protein, and activity. In addition, the levels of CYP3A4 in untreated cells were decreased following arsenite treatment. Transcription of the CYP3A4 gene is primarily regulated by heterodimers of the retinoid X receptor alpha (RXRalpha) and the pregnane X receptor (PXR). We found that arsenite failed to affect expression of PXR or the transcription factor Sp1, yet caused a significant decrease in PXR responsiveness to Rif. Arsenite caused a large decrease in nuclear RXRalpha protein and, to a lesser extent, RXRalpha mRNA. These results suggest that arsenite inhibits both untreated and induced CYP3A4 transcription in primary human hepatocytes by decreasing the activity of PXR, as well as expression of the nuclear receptor RXRalpha.",
Arsenic,1797806,"Influence of compost on the mobility of arsenic in soil and its uptake by bean plants (Phaseolus vulgaris L.) irrigated with arsenite-contaminated water Abstract: The influence of compost on the growth of bean plants irrigated with As-contaminated waters and its influence on the mobility of As in the soils and the uptake of As (as NaAs(III)O2) by plant components was studied at various compost application rates (3·10(4) and 6·10(4) kg ha(-1)) and at three As concentrations (1, 2 and 3 mg kg(-1)). The biomass and As and P concentrations of the roots, shoots and beans were determined at harvest time, as well as the chlorophyll content of the leaves and nonspecific and specifically bound As in the soil. The bean plants exposed to As showed typical phytotoxicity symptoms; no plants however died over the study. The biomass of the bean plants increased with the increasing amounts of compost added to the soil, attributed to the phytonutritive capacity of compost. Biomass decreased with increasing As concentrations, however, the reduction in the biomass was significantly lower with the addition of compost, indicating that the As phytotoxicity was alleviated by the compost. For the same As concentration, the As content of the roots, shoots and beans decreased with increasing compost added compared to the Control. This is due to partial immobilization of the As by the organic functional groups on the compost, either directly or through cation bridging. Most of the As adsorbed by the bean plants accumulated in the roots, while a scant allocation of As occurred in the beans. Hence, the addition of compost to soils could be used as an effective means to limit As accumulation in crops from As-contaminated waters.",
Arsenic,90046,"Cumulative arsenic exposure and lung cancer in smelter workers: A dose-response study Abstract: The cause-specific mortality was followed through 1981 in a cohort of 3,916 male Swedish smelter workers employed for at least 3 months from 1928 through 1967. Arsenic levels in the air of all workplaces within the smelter were estimated for three different time periods. Using this exposure matrix and detailed information of the work history, cumulative arsenic exposure could be computed for each worker. Standardized mortality ratios (SMRs) were calculated for several dose categories using age-specific mortality rates from the county where the smelter was situated. A positive dose-response relationship was found between cumulative arsenic exposure and lung cancer mortality with an overall SMR of 372 (304-450, 95% confidence interval). The lung cancer mortality was related to the estimated average intensity of exposure to arsenic but not to the duration. No positive dose-response relationship was found between arsenic and ischemic heart disease or cerebrovascular disease. There was also no evident dose-response relationship between estimated exposure to sulfur dioxide and lung cancer.",
Arsenic,2278999,"Comparison of two blanket surveys of arsenic in tubewells conducted 12years apart in a 25km(2) area of Bangladesh Abstract: The arsenic (As) content of groundwater pumped from all tubewells within 61 contiguous villages of Araihazar, Bangladesh, was determined a first time in 2000-01 with laboratory measurements and a second time in 2012-13 using the ITS Arsenic Econo-Quick kit. The two surveys indicate that the total number of tubewells within the area almost doubled from 5560 to 10,879 over 12years. The evolution of the distribution of well ages between the two surveys is consistent with a simple model that combines an annual increase of 42wells/year in the rate of installations within the 61 villages starting in 1980 and a 7%/year rate of abandonment of wells as a function of well age. Colored placards were posted on each pumphead in 2012-13 on the basis of the kit results relative to the WHO guideline for As and the Bangladesh standard for As in drinking water: blue for As?10?g/L, green&gt;10-50?g/L, and red: &gt;50?g/L. According to quality-control samples collected from 502 tubewells for comparing the kit results with laboratory measurements, not a single well labeled blue in 2012-13 should have been labeled red and vice-versa. Field-kit testing in 2012-13 did not change the status of wells relative to the Bangladesh standard of 876 (87%) out of 1007 wells with a placard based on laboratory measurements in 2000-01 still attached to the pumphead. The high proportion of tubewells believed by households to be unsafe (66% out of 2041) that were still used for drinking and cooking in 2012-13 underlines the need for more widespread testing to identify low-As wells as an alternative source of drinking water.",
Arsenic,1936097,"Biomethylation and volatilization of arsenic by the marine microalgae Ostreococcus tauri Abstract: Ostreococcus tauri is a marine green microalga, recognized as a model organism of the marine phytoplankton assemblage and widely distributed from coastal to oligotrophic waters. This study showed it could tolerate both arsenite and arsenate concentrations of up to 100?M, and cellular As concentration increased significantly (P&lt;0.01) with increasing concentration of As(V) in the medium (0-50?M). It was revealed that As biotransformations were mediated by algal cells. Volatilized As was detected and the ability of As biovolatilization by O. tauri was demonstrated. The reduction of As(V) to As(III) might be the limiting step for As methylation and volatilization from seawater since the treatment with As(III) yielded five times more volatile As as compared to that with As(V). Arsenic biogeochemical cycle in the marine environment might play an important role based on the huge surface area of ocean (71%) and the massive number of marine phytoplankton.",
Arsenic,2279580,"Insights into the relationship between antimicrobial residues and bacterial populations in a hospital-urban wastewater treatment plant system Abstract: The relationship between antimicrobial residues, antibiotic resistance prevalence and bacterial community composition in hospital effluent and in the receiving wastewater treatment plant was studied. Samples from hospital effluent, raw inflow and final effluent of the receiving wastewater treatment plant were characterized for amoxicillin and ciprofloxacin resistance prevalence, content of heavy metals and antimicrobial residues and bacterial community structure, based on 16S rRNA gene PCR-DGGE analysis. The concentration of fluoroquinolones, arsenic and mercury was in general higher in hospital effluent than in raw inflow, while the opposite was observed for tetracyclines, sulfonamides and penicillin G. The prevalence of ciprofloxacin resistance was significantly higher in hospital effluent than in raw inflow. The concentration of antimicrobial residues was observed to be significantly correlated with the prevalence of antibiotic resistant bacteria and with variations in the bacterial community. Hospital effluent was confirmed as a relevant, although not unique, source of antimicrobial residues and antibiotic resistant bacteria to the wastewater treatment plant. Moreover, given the high loads of antibiotic residues and antibiotic resistant bacteria that may occur in hospital effluents, these wastewater habitats may represent useful models to study and predict the impact of antibiotic residues on bacterial communities.",
Arsenic,2064226,"Noble metal nanoclusters and nanoparticles precede mineral formation in magmatic sulphide melts Abstract: In low temperature aqueous solutions, it has long been recognized by in situ experiments that many minerals are preceded by crystalline nanometre-sized particles and non-crystalline nanophases. For magmatic systems, nanometre-sized precursors have not yet been demonstrated to exist, although the suggestion has been around for some time. Here we demonstrate by high temperature quench experiments that platinum and arsenic self-organize to nanoparticles, well before the melt has reached a Pt-As concentration at which discrete Pt arsenide minerals become stable phases. If all highly siderophile elements associate to nanophases in undersaturated melts, the distribution of the noble metals between silicate, sulphide and metal melts will be controlled by the surface properties of nano-associations, more so than by the chemical properties of the elements.",
Arsenic,193263,"Micronuclei as biomarkers of carcinogen exposure in populations exposed to arsenic through drinking water in West Bengal, India: A comparative study in three cell types Abstract: Contamination of groundwater by arsenic, a paradoxical human carcinogen, has become a cause of global public health concern. In West Bengal, India, the groundwater in 9 of 18 districts is heavily contaminated with arsenic. Various adverse health effects including cancer have been reported from these districts and are associated with prolonged arsenic exposure. A cross-sectional biomarker study was conducted to evaluate and compare the frequencies of micronuclei in peripheral blood lymphocytes, oral mucosa cells, and urothelial cells from the inhabitants of North 24 Parganas, one of the arsenic-affected districts. The three cell types were collected from 163 residents exposed to high levels of arsenic in drinking water (214.7213 +/- 9.0273 microg/l) and from 154 unexposed subjects residing in the unaffected East Midnapur district with very little or no exposure to arsenic through drinking water (9.2017 +/- 0.3157 microg/l). Our analysis revealed that micronuclei frequencies in the exposed group were significantly elevated to 5.33-fold over unexposed levels for lymphocytes, 4.63-fold for oral mucosa cells, and 4.71-fold for urothelial cells (increases in micronuclei frequencies significant at P < 0.01). The results indicate that chronic ingestion of arsenic in drinking water by the exposed subjects is linked to the enhanced incidence of micronuclei in all the three cell types, slightly higher level of micronuclei being observed in lymphocytes compared with oral mucosa and urothelial cells.",
Arsenic,2345606,"Potential human health risk by metal(loid)s, 234,238U and 210Po due to consumption of fish from the ""Luis L. Leon"" reservoir (Northern México) Abstract: Concentrations of As, Cu, Fe, Hg, Pb and Zn and activity concentrations from 234,238U and 210Po in water, fillet, liver and gills were determined in three stocked fish species from the Luis L. Leon reservoir, located in Northern Mexico. The considered species were Lepomis cyanellus, Cyprinus carpio and Ictalurus furcatus. 238U and 234U activity concentration (AC) in fillet samples showed values of 0.007-0.014 and 0.01-0.02 Bq?kg-1 wet weight (ww), respectively. Liver samples for L. cyanellus, C. carpio and I. furcatus present 210Po AC of 1.16-3.26, 0.70-1.13 and 0.93-1.37 Bq?kg-1 ww. Arsenic, mercury and lead concentration intervals in fillet samples were 0.13-0.39, 0.005-0.126 and 0.009-0.08 mg?kg-1 ww, respectively, while in gill samples they were 0.11-0.43, 0.002-0.039 and 0.02-0.26 mg?kg-1 ww. The elemental Bioaccumulation Factor (BAF) for fish tissues with respect to their concentrations in water was determined. L. cyanellus showed the highest BAF values for As and total U, being BAFAs = 37 and 40 L?kg-1 in fillet and gills, respectively, and BAFU total = 1.5 L?kg-1 in fillet. I. furcatus showed the highest BAF values for Hg and Pb, being BAFHg = 40 and 13 L?kg-1 in fillet and gills, and BAFPb = 6.5 and 22 L?kg-1 in fillet and gills, respectively. Some metal(loid) concentrations are slightly higher than European regulations for fish fillets. The difference in concentrations of metal(loid)s in fillet among the studied species is probably due to their differences in diet and habitat.",
Arsenic,1357737,"A soft tissue sarcoma case control study in a large multi-chemical manufacturing facility Abstract: Deaths due to soft tissue sarcomas were identified among Dow Chemical Company employees at their Midland, Michigan, location and a comparison was then made of the occupational exposures of these individuals against those of a comparison group. Thirteen chemicals known to have an association with soft tissue sarcomas were identified as being used or found in the Midland location for some time since 1940. These included: arsenic (7440382), benzopyrene (50328), cadmium (7440439), chlorinated dioxins, butadiene (106990), chloromethyl-methyl-ether (107302) (CCME), chromium (7440473), ethylene-dibromide (106934) (EDB), ethylene-dichloride (107062) (EDC), hydrazine (302012), nickel (7440020), thorium-oxide (1314201), and vinyl-chloride (75014). A total of 14 cases were found and compared against 126 matched comparisons. Some individuals were exposed to multiple chemicals during their employment at the company. No statistically significant odds ratios were found for any of the chemicals of interest. None of the cases had exposure to the higher chlorinated dioxins. The authors conclude that this study does not support a causal association between soft tissue sarcoma and any of the aforementioned chemicals.",
Arsenic,1070343,"Effects of arsenite and UVA-1 radiation on calcineurin signaling Abstract: Calcineurin is a Ca(2+)-dependent serine/threonine phosphatase and the target of the immunosuppressive drugs cyclosporin and tacrolimus, which are used in transplant recipients to prevent rejection. Unfortunately, the therapeutic use of this drugs is complicated by a high incidence of skin malignancy, which has set off a number of studies into the role of calcineurin signaling in skin, particularly with respect to cell cycle control and DNA repair. Both UVA1 radiation and arsenic species are known to promote skin cancer development via production of reactive oxygen species. In light of the well-documented sensitivity of calcineurin to oxidative stress, we examined and compared the effects of UVA1 and arsenite on calcineurin signaling. In this paper, we show that physiologically relevant doses of UVA1 radiation and low micromolar concentrations of arsenite strongly inhibit calcineurin phosphatase activity in Jurkat and skin cells and decrease NFAT nuclear translocation in Jurkat cells. The effects on calcineurin signaling could be partly prevented by inhibition of NADPH oxidase in Jurkat cells or increased dismutation of superoxide in Jurkat and skin cells. In addition, both UVA1 and arsenite decreased NF-?B activity, although at lower concentrations, arsenite enhanced NF-?B activity. These data indicate that UVA1 and arsenite affect a signal transduction route of growingly acknowledged importance in skin and that calcineurin may serve as a potential link between ROS exposure and impaired tumor suppression.",
Arsenic,2215731,"Prenatal arsenic exposure and the epigenome: Altered microRNAs associated with innate and adaptive immune signaling in newborn cord blood Abstract: The Biomarkers of Exposure to ARsenic (BEAR) pregnancy cohort in Gómez Palacio, Mexico was recently established to better understand the impacts of prenatal exposure to inorganic arsenic (iAs). In this study, we examined a subset (n?=?40) of newborn cord blood samples for microRNA (miRNA) expression changes associated with in utero arsenic exposure. Levels of iAs in maternal drinking water (DW-iAs) and maternal urine were assessed. Levels of DW-iAs ranged from below detectable values to 236 µg/L (mean?=?51.7 µg/L). Total arsenic in maternal urine (U-tAs) was defined as the sum of iAs and its monomethylated and dimethylated metabolites (MMAs and DMAs, respectively) and ranged from 6.2 to 319.7 µg/L (mean?=?64.5 µg/L). Genome-wide miRNA expression analysis of cord blood revealed 12 miRNAs with increasing expression associated with U-tAs. Transcriptional targets of the miRNAs were computationally predicted and subsequently assessed using transcriptional profiling. Pathway analysis demonstrated that the U-tAs-associated miRNAs are involved in signaling pathways related to known health outcomes of iAs exposure including cancer and diabetes mellitus. Immune response-related mRNAs were also identified with decreased expression levels associated with U-tAs, and predicted to be mediated in part by the arsenic-responsive miRNAs. Results of this study highlight miRNAs as novel responders to prenatal arsenic exposure that may contribute to associated immune response perturbations. Environ. Mol. Mutagen., 2013. © 2013 Wiley Periodicals, Inc.",
Arsenic,2149096,"Large area photoconductive terahertz emitter for 1.55 ?m excitation based on an InGaAs heterostructure Abstract: We present scalable large area terahertz (THz) emitters based on a nanoscale multilayer InGaAs/InAlAs heterostructure and a microstructured electrode pattern. The emitters are designed for pump lasers working at the telecommunication wavelength of 1.55 ?m. Electric THz fields of more than 2.5 V cm?¹ are reached with moderate pump powers of 80 mW, the corresponding spectrum extends up to 3 THz. The saturation characteristics have been investigated for different pump laser spot sizes. For small pump powers of less than 50 mW the emitted THz field is nearly independent of the spot size, for higher pump powers and small spot sizes a clear saturation of the generated THz pulse can be observed. Hence the use of scalable emitters is especially promising for high power fibre laser systems. The spectral content of the generated radiation is nearly independent of the parameters spot size, pump power, and bias voltage, which allows for stable operation in spectroscopic applications.",
Arsenic,1677564,"Biological and behavioral factors modify biomarkers of arsenic exposure in a U.S. population Abstract: Although consumption of drinking water contaminated with inorganic arsenic is usually considered the primary exposure route, aggregate exposure to arsenic depends on direct consumption of water, use of water in food preparation, and the presence in arsenicals in foods. To gain insight into the effects of biological and behavioral factors on arsenic exposure, we determined arsenic concentrations in urine and toenails in a U.S. population that uses public or private water supplies containing inorganic arsenic. Study participants were 904 adult residents of Churchill County, Nevada, whose home tap water supplies contained &lt;3 to about 1200µg of arsenic per liter. Biomarkers of exposure for this study were summed urinary concentrations of inorganic arsenic and its methylated metabolites (speciated arsenical), of all urinary arsenicals (total arsenical), and of all toenail arsenicals (total arsenical). Increased tap water arsenic concentration and consumption were associated with significant upward trends for urinary speciated and total and toenail total arsenical concentrations. Significant gender differences in concentrations of speciated and total arsenicals in urine and toenails reflected male-female difference in water intake. Both recent and higher habitual seafood consumption significantly increased urinary total but not speciated arsenical concentration. In a stepwise general linear model, seafood consumption significantly predicted urinary total arsenical but not urinary speciated or toenail total arsenical concentrations. Smoking behavior significantly predicted urinary speciated or total arsenical concentration. Gender, tap water arsenic concentration, and primary drinking water source significantly predicted urinary speciated and total concentrations and toenail total arsenical concentrations. These findings confirm the primacy of home tap water as a determinant of arsenic concentration in urine and toenails. However, biological and behavioral factors can modify exposure-response relations for these biomarkers. Refining estimates of the influence of these factors will permit better models of dose-response relations for this important environmental contaminant.",
Arsenic,2347772,"A structural approach to address the healthy-worker survivor effect in occupational cohorts: an application in the trucking industry cohort Abstract: Background Occupational cohort studies are often challenged by the Healthy Worker Survivor Effect, which may bias standard methods of analysis. G-estimation of structural failure time models is an approach for reducing this type of bias. Accelerated failure time models have recently been applied in an occupational cohort but cumulative failure time models have not. <br> <br>Methods We used g-estimation of a cumulative failure time model to assess the effect of working as a long-haul driver on ischaemic heart disease mortality in a cohort of 30 448 men employed in the unionised US trucking industry in 1985. Exposure was defined by job title and based on work records. We also applied g-estimation of an accelerated failure time model as a sensitivity analysis and approximated HRs from both models to compare them. <br> <br>Results The risk ratio (RR) obtained from the cumulative failure time model, comparing the observed risk under no intervention to the risk had nobody ever been exposed as a long-haul driver, was 1.09 (95% CI 1.02 to 1.16). The RR comparing the risk had everyone been exposed as long-haul driver for 8 years to the risk had nobody ever been exposed was 1.20 (95% CI 1.04 to 1.46). After HR approximations, accelerated failure time model results were similar. <br> <br>Conclusions The cumulative failure time model can effectively control time-varying confounding by Healthy Worker Survivor Effect, and provides an easily interpretable effect estimate. RRs estimated from the cumulative failure time model indicate an elevated ischaemic heart disease mortality risk for long-haul drivers in the US trucking industry.",
Arsenic,2343466,"Heavy metal uptake and toxicity in the presence of titanium dioxide nanoparticles: A factorial approach using Daphnia magna Abstract: Unintentionally released titanium dioxide nanoparticles (nTiO2) may co-occur in aquatic environments together with other stressors, i.e. metal ions. The effects of P25-nTiO2 on the toxicity and uptake of the elements silver (Ag), arsenic (As) and copper (Cu) were assessed by applying a factorial test design. The test design consisted of two developmental stages of Daphnia magna, two levels of nTiO2 (0 versus 2 mg/L) as well as seven nominal test concentrations of the respective element. The presence of nTiO2 increased Ag toxicity for juveniles as indicated by a 40% lower 72-h EC50, while the toxicities of As and Cu were reduced by up to 80%. This reduction was even more pronounced for Cu in the presence of dissolved organic carbon (i.e. seaweed extract) and nTiO2. This outcome coincides with the body burden of the elements, which was elevated two-fold for Ag and decreased fourteen-fold for Cu in the presence of nTiO2. Although the underlying mechanisms could not be uncovered, the data suggest that the carrier function of nTiO2 plays a central role. However, to understand the processes and mechanisms occurring in the field due to the presence of nTiO2 further systematic investigations considering environmental variables and nanoparticle characteristics are required.",
Arsenic,710871,"Association between low-level environmental arsenic exposure and QT interval duration in a general population study Abstract: High-level arsenic exposure is consistently associated with QT prolongation, a risk factor for arrhythmia and sudden cardiac death. Arsenic may act on QT by increasing cardiac calcium currents. The authors hypothesized that low-level arsenic exposure would be associated with QT duration and that this effect would be stronger among persons not using calcium channel blockers. They performed a cross-sectional analysis in elderly men from the Normative Aging Study to analyze associations between toenail arsenic and QT and heart rate-corrected QT (QTc) durations and to examine effect modification by calcium channel blocker use, using linear regression and adjusting for potential confounders. Participants were examined in Boston, Massachusetts, between 2000 and 2002 or in 2006. An interquartile range increase in arsenic concentration was associated with a 3.8-millisecond increase in QT (95% confidence interval: 0.82, 6.8) and a 2.5-millisecond increase in QTc (95% confidence interval: 0.11, 4.9). There was no evidence of effect modification by medication use for either QT (P = 0.93) or QTc (P = 0.58). The authors observed positive associations between a biomarker of arsenic exposure and QT duration but found no evidence of effect modification by calcium channel blocker use, possibly because of modest power.",
Arsenic,1352209,Adsorption of Phosphate from Aqueous Solution Using an Iron-Zirconium Binary Oxide Sorbent Abstract: ,
Arsenic,1378978,ARSENIC INDUCES DECREASED EXPRESSION OF BETA-2-ADRENERGIC RECEPTORS IN CULTURED KERATINOCYTES Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN INTEGUMENTARY SYSTEM ARSENIC CARCINOGEN BETA-ADRENERGIC RECEPTORS EXPRESSION KERATINOCYTES SKIN CANCER RECEPTOR DENSITY TOXICOLOGY INTEGUMENTARY SYSTEM NEOPLASTIC DISEASE INTEGUMENTARY SYSTEM DISEASE,
Arsenic,2347620,"Density functional theory calculations on the complexation of p-arsanilic acid with hydrated iron oxide clusters: Structures, reaction energies, and transition states Abstract: Aromatic organoarsenicals, such as p-arsanilic acid (pAsA), are still used today as feed additives in the poultry and swine industries in developing countries. Through the application of contaminated litter as a fertilizer, these compounds enter the environment and interact with reactive soil components such as iron and aluminum oxides. Little is known about these surface interactions at the molecular level. We report density functional theory (DFT) calculations on the energies, optimal geometries, and vibrational frequencies for hydrated pAsA/iron oxide complexes, as well as changes in Gibbs free energy, enthalpy, and entropy for various types of ligand exchange reactions leading to both inner- and outer-sphere complexes. Similar calculations using arsenate are also shown for comparison, along with activation barriers and transition state geometries between inner-sphere complexes. Minimum energy calculations show that the formation of inner- and outer-sphere pAsA/iron oxide complexes is thermodynamically favorable, with the monodentate mononuclear complexes being the most favorable. Interatomic As-Fe distances are calculated to be between 3.3 and 3.5 Å for inner-sphere complexes and between 5.2 and 5.6 Å for outer-sphere complexes. In addition, transition state calculations show that activation energies greater than 23 kJ/mol are required to form the bidentate binuclear pAsA/iron oxide complexes, and that formation of arsenate bidentate binuclear complexes is thermodynamically -rather than kinetically- driven. Desorption thermodynamics using phosphate ions show that reactions are most favorable using HPO4(2-) species. The significance of our results for the overall surface complexation mechanism of pAsA and arsenate is discussed.",
Arsenic,2279303,"The fronds tonoplast quantitative proteomic analysis in arsenic hyperaccumulator Pteris vittata L Abstract: Pteris vittata, the first known arsenic hyperaccumulating plant, can accumulate very high concentration arsenic in its aboveground tissues, while low in roots. Previous studies have suggested that arsenic vacuole compartmentalization may play an important role in the arsenic-hyperaccumulation in P. vittata, but the mechanism(s) of arsenic transport to vacuole are largely unknown. We obtained tonoplast isolated from fronds of P. vittata sporophyte grown under minus and 1mM arsenate for 3weeks by iodixanol step gradient centrifugation method, and then used TMPP protein labeling technology followed by liquid chromatography-a linear ion trap-Orbitrap hybrid mass spectrometer analysis for the quantitative detection of proteins. And we designed and used an ""artificial"" database for database searching. In total, 56 tonoplast proteins were identified; more than 70% of them were transport proteins. Under arsenate treatment, one TDT transporter protein, a member of the TerC family and a PDR-like protein were upregulated differentially. While V-ATPase subunits c, E, and G, and V-PPase, were downregulated. Additionally, the identified tonoplast proteins in our present study provide an informative basis for arsenic carriers or channels and help to clarify the regulation of tonoplast arsenic transport processes in P. vittata.<br /><br /><strong>BIOLOGICAL SIGNIFICANCE: </strong>Vacuole compartmentalization is crucial to As hyperaccumulator P. vittata, while there is limited known arsenic transport proteins involved in vacuole compartmentalization. In this paper, we obtained tonoplast of P. vittata fronds by iodixanol step gradient centrifugation method and then used TMPP protein labeling proteome technology for the quantitative detection of fronds tonoplast proteins. Our findings are the first challenge to the tonoplast proteins data mining of P. vittata which provide an informative basis for As carriers or channels. The proteomic approach in our study is suited for detecting alterations tonoplast protein and help to clarify the regulation of tonoplast transport processes. This article is part of a Special Issue entitled: Proteomics of non-model organisms.",
Arsenic,1579388,"Grapevine trunk diseases: Complex and still poorly understood Abstract: This review presents an overview of eutypa dieback, esca and botryosphaeria dieback, the predominant grapevine trunk diseases worldwide. It covers their symptomatologies in the trunk, leaves and berries; the characteristics of the different fungal species associated with them; and host–pathogen interactions. Here, the host–pathogen relationship is defined at the cytological, physiological and molecular levels. Currently available experimental tools for studying these diseases, both in vitro and in the field, are discussed. Finally, a progress report on their control, which, since the ban of sodium arsenite, comprises chemical, biological and/or sanitation methods, is presented.",
Arsenic,1385722,"Acute health effects of community exposure to cotton defoliants Abstract: BIOSIS COPYRIGHT: BIOL ABS. In September and October of 1987, the California Department of Health Services responded to community complaints by investigating the relationship between health symptoms and community exposure to cotton defoliants. Symptoms experienced during the 1987 cotton defoliation season by 232 residents of cotton-growing communities were compared with symptoms of 175 residents of non-cotton-growing agricultural communities. Fatigue, eye irritation, rhinitis, throat irriatation, nausea, and diarrhea were statistically elevated in rates adjusted for age, sex, and race and were reported 60-100% more frequently by respondents living or working near sprayed cotton fields than by the comparison group. These symptoms rate elevations were substantially unchanged even after adjustment by a model of potentially confounding factors that included cigarette smoking, chronic illness, and some additional demographic variables.",
Arsenic,67507,"An ecologic study of skin cancer and environmental arsenic exposure Abstract: We conducted an epidemiologic study of skin cancer incidence rates for four counties in Montana. The two counties considered to be exposed to arsenic were Deer Lodge, containing the former Anaconda copper smelter, and Silver Bow, containing an open pit copper mine. Residents in these counties had potential exposure to arsenic and other heavy metals. Gallatin and Park counties served as controls. All histologically proven skin cancer cases during the period January 1980 through June 1986 were collected from pathology services and dermatologists in these four counties. In addition, all skin cancer cases from four dermatologists practicing in urban referral areas outside the counties were reviewed. Results were analyzed by individual as well as by two different definitions of anatomically distinct lesions: the National Cancer Institute (NCI) definition and the study definition. There were 1616 individuals with skin cancer in the four counties during the period under consideration, yielding 2252 (NCI definition) and 2451 (study definition) cases. The clinical features of the skin cancers in the exposed counties were not similar to those described for arsenic-related skin cancer. The age-adjusted annual skin cancer rates were higher for the two control counties as compared to either the county with the former smelter, Deer Lodge, or the county with the mine, Silver Bow. Our results cannot be explained by differences in ascertainment, latitude, or altitude. They can be partially explained by differences in both outdoor employment and medical practice. The overall skin cancer incidence rates for the exposed counties were well within the range of skin cancer rates observed for other locations in the United States.",
Arsenic,1256728,"Selectivity of arsenite interaction with zinc finger proteins Abstract: Arsenic is a carcinogenic element also used for the treatment of acute promyelocytic leukemia. The reactivity of proteins to arsenic must be associated with the various biological functions of As. Here, we investigated the selectivity of arsenite to zinc finger proteins (ZFPs) with different zinc binding motifs (C2H2, C3H, and C4). Single ZFP domain proteins were used for the direct comparison of the reactivity of different ZFPs. The binding constants and the reaction rates have been studied quantitatively. Results show that both the binding affinity and reaction rates of single-domain ZFPs follow the trend of C4 &gt; C3H ? C2H2. Compared with the C2H2 motif ZFPs, the binding affinities of C3H and C4 motif ZFPs are nearly two orders of magnitude higher and the reaction rates are approximately two-fold higher. The formation of multi-domain ZFPs significantly enhances the reactivity of C2H2 type ZFPs, but has negligible effects on C3H and C4 ZFPs. Consequently, the reactivities of the three types of multi-domain ZFPs are rather similar. The 2D NMR spectra indicate that the As(III)-bound ZFPs are also unfolded, suggesting that arsenic binding interferes with the function of ZFPs.",
Arsenic,2088327,"Effects of simultaneous arsenic and iron toxicities on rice (Oryza sativa L.) development, yield-related parameters and As and Fe accumulation in relation to As speciation in the grains Abstract: ",
Arsenic,2088456,"The kinetic signature of toxicity of four heavy metals and their mixtures on MCF7 breast cancer cell line Abstract: This study evaluated the kinetic signature of toxicity of four heavy metals known to cause severe health and environmental issues-cadmium (Cd), mercury (Hg) lead (Pb) arsenic (As)-and the mixture of all four metals (Mix) on MCF7 cancer cells, in the presence and absence of the antioxidant glutathione (GSH). The study was carried out using real time cell electronic sensing (RT-CES). RT-CES monitors in real time the electrical impedance changes at the electrode/culture medium interface due to the number of adhered cells, which is used as an index of cell viability. Cells were seeded for 24 h before exposure to the metals and their mixtures. The results showed that in the presence and absence of cellular glutathione, arsenic was the most cytotoxic of all five treatments, inducing cell death after 5 h of exposure. Lead was the least cytotoxic in both scenarios. In the presence of cellular GSH, the cytotoxic trend was As > Cd > MIX > Hg > Pb, while in the absence of GSH, the cytotoxic trend was As > Hg > MIX > Cd > Pb. The findings from this study indicate the significance of glutathione-mediated toxicity of the metals examined-particularly for mercury-and may be clinically relevant for disorders such as autism spectrum disorder where decreased glutathione-based detoxification capacity is associated with increased mercury intoxication.",
Arsenic,656819,"A biologically based model of growth and senescence of Syrian hamster embryo (SHE) cells after exposure to arsenic Abstract: We modified the two-stage Moolgavkar-Venzon-Knudson (MVK) model for use with Syrian hamster embryo (SHE) cell neoplastic progression. Five phenotypic stages are proposed in this model: Normal cells can either become senescent or mutate into immortal cells followed by anchorage-independent growth and tumorigenic stages. The growth of normal SHE cells was controlled by their division, death, and senescence rates, and all senescent cells were converted from normal cells. In this report, we tested the modeling of cell kinetics of the first two phenotypic stages against experimental data evaluating the effects of arsenic on SHE cells. We assessed cell division and death rates using flow cytometry and correlated cell division rates to the degree of confluence of cell cultures. The mean cell death rate was approximately equal to 1% of the average division rate. Arsenic did not induce immortalization or further mutations of SHE cells at concentrations of 2 microM and below, and chromium (3.6 microM) and lead (100 microM) had similar negative results. However, the growth of SHE cells was inhibited by 5.4 microM arsenic after a 2-day exposure, with cells becoming senescent after only 16 population doublings. In contrast, normal cells and cells exposed to lower arsenic concentrations grew normally for at least 30 population doublings. The biologically based model successfully predicted the growth of normal and arsenic-treated cells, as well as the senescence rates. Mechanisms responsible for inducing cellular senescence in SHE cells exposed to arsenic may help explain the apparent inability of arsenic to induce neoplasia in experimental animals.",
Arsenic,1337272,"Microbial community structure and sulfur biogeochemistry in mildly-acidic sulfidic geothermal springs in Yellowstone National Park Abstract: Geothermal and hydrothermal waters often contain high concentrations of dissolved sulfide, which reacts with oxygen (abiotically or biotically) to yield elemental sulfur and other sulfur species that may support microbial metabolism. The primary goal of this study was to elucidate predominant biogeochemical processes important in sulfur biogeochemistry by identifying predominant sulfur species and describing microbial community structure within high-temperature, hypoxic, sulfur sediments ranging in pH from 4.2 to 6.1. Detailed analysis of aqueous species and solid phases present in hypoxic sulfur sediments revealed unique habitats containing high concentrations of dissolved sulfide, thiosulfate, and arsenite, as well as rhombohedral and spherical elemental sulfur and/or sulfide phases such as orpiment, stibnite, and pyrite, as well as alunite and quartz. Results from 16S rRNA gene sequencing show that these sediments are dominated by Crenarchaeota of the orders Desulfurococcales and Thermoproteales. Numerous cultivated representatives of these lineages, as well as the Thermoproteales strain (WP30) isolated in this study, require complex sources of carbon and respire elemental sulfur. We describe a new archaeal isolate (strain WP30) belonging to the order Thermoproteales (phylum Crenarchaeota, 98% identity to Pyrobaculum/Thermoproteus spp. 16S rRNA genes), which was obtained from sulfur sediments using in situ geochemical composition to design cultivation medium. This isolate produces sulfide during growth, which further promotes the formation of sulfide phases including orpiment, stibnite, or pyrite, depending on solution conditions. Geochemical, molecular, and physiological data were integrated to suggest primary factors controlling microbial community structure and function in high-temperature sulfur sediments.",
Arsenic,1352415,"APPLICATION OF ATOMIC-ABSORPTION SPECTROPHOTOMETRY TO DETERMINATION OF ARSENIC IN FOODSTUFFS - GERMAN - ROSCHNIK,RK Abstract: ",
Arsenic,1034027,"Arsenate induces stress proteins in cultured rat myoblasts Abstract: The induction of stress proteins was examined in rat myoblast cultures by two-dimensional gel electrophoresis. Data obtained by this analysis led to the following observations. (a) Arsenate, which behaves as a phosphate analogue in cellular phosphate-transfer reactions, stresses cultured rat cells and induces the synthesis of a unique set of proteins. (b) Most of the proteins synthesized after the addition of arsenate are identical to proteins synthesized in rat myoblasts in response to heat shock or arsenite stress. (c) However, both arsenic salts induce the synthesis of two unique proteins not induced by heat shock. (d) Five 25-30-kdalton stress proteins of rat cells do not contain methionine residues. (e) A majority of the proteins synthesized in stressed myogenic cells are also induced by stress in other rat cells such as hepatoma cells, pituitary tumor cells, and fibroblasts. The 25-30-kdalton stress-related proteins identified in myogenic cells, on the other hand, are induced in fibroblasts but not hepatoma or pituitary cells.",
Arsenic,1519093,"Protective role of AQP3 in UVA-induced NHSFs apoptosis via Bcl2 up-regulation Abstract: Aquaporin-3 (AQP3), a water/glycerol-transporting protein that facilitates water, urea, and glycerol transport, can inhibit arsenite-induced apoptosis by up-regulating Bcl-2. However, whether it has a protective role in ultraviolet A (UVA)-induced apoptosis in normal human skin fibroblasts is not known. In this study, we demonstrate that mild UVA treatment fails to induce oxidative cell stress and apoptosis in normal human skin fibroblasts (NHSFs) overexpressing AQP3. After severe UVA irradiation, there was an increase in oxidative cell stress and apoptosis when AQP3 levels decreased. We also found that silencing AQP3 sensitized NHSFs to low-dose UVA. Overexpressing AQP3 was protective against high-dose UVA-induced oxidative stress and apoptosis. Besides, we observed that Bcl-2 may be involved in UVA-induced apoptosis. Our findings suggested that the water/glycerol-transporting protein AQP3 plays a role in resistance to UVA-induced apoptosis.",
Arsenic,1936066,"Arsenic Removal from Contaminated Water Using Three-Dimensional Graphene-Carbon Nanotube-Iron Oxide Nanostructures Abstract: We report a highly versatile and one-pot microwave route to the mass production of three-dimensional graphene-carbon nanotube-iron oxide nanostructures for the efficient removal of arsenic from contaminated water. The unique three-dimensional nanostructure shows that carbon nanotubes are vertically standing on graphene sheets and iron oxide nanoparticles are decorated on both the graphene and the carbon nanotubes. The material with iron oxide nanoparticles shows excellent absorption for arsenic removal from contaminated water, due to its high surface-to-volume ratio and open pore network of the graphene-carbon nanotube-iron oxide three-dimensional nanostructures.",
Arsenic,1508639,"Silencing of the human SET gene in vitro with lentivirus-mediated RNA interference Abstract: In our previous study, SET was identified as one of the differentially expressed proteins that was associated with tetra-arsenic tetra-sulfide (As4S4)-induced NB4-R1 [retinoic acid-resistant acute promyelocytic leukemia (APL) cell line] apoptosis. However, the mechanism through which SET regulates pathways during this process remains unclear. The aim of this study was to construct lentivirus-mediated short hairpin RNA (shRNA) against SET and investigate the effect of SET on As4S4-induced retinoic acid-resistant APL cell apoptosis. In the present study, 4 different oligonucleotides targeting the human SET gene were synthesized and cloned into the eukaryotic expression plasmid pGCSIL-GFP. The recombinant vectors were introduced into NB4-R1 cells. The silencing efficiency was measured by real-time quantitative PCR (RT-qPCR) and western blotting. Our results showed that the 4 recombinant RNA interference (RNAi) vectors were constructed successfully. Fluorescence microscopy demonstrated that infection efficiency ranged from 70 to 90%. Infection with the 4 different RNAi vectors significantly knocked down the expression of SET by 52.8, 69.1, 48.9 and 90.3% at the mRNA level, and 92.5, 96.3, 91.7 and 98.4% at the protein level, respectively. We attempt to clarify the mechanism of As4S4 treatment on retinoic acid-resistant APL.",
Arsenic,2088326,Effects of waterlogging on the solubility and redox state of Sb in a shooting range soil and its uptake by grasses: a tank experiment Abstract: ,
Arsenic,627386,"Increased chromosome-type chromosome aberration frequencies as biomarkers of cancer risk in a blackfoot endemic area Abstract: To examine whether biomarkers such as sister chromatid exchanges (SCEs) and chromosome aberrations (CAs) can predict cancer development, a nested case-control study was performed in a blackfoot endemic area with a known high cancer risk. A cohort of 686 residents was recruited from three villages in the blackfoot endemic area. Personal characteristics were collected, and venous blood was drawn for lymphocyte culture and stored in a refrigerator. The vital status and cancer development were followed using the National Death Registry, Cancer Registry, and Blackfoot Disease Registry. The follow-up period was from August 1991 to July 1995. During this 4-year period, 31 residents developed various types of cancer. Blood culture samples from nine of these subjects were unsuitable for experiments due to improper storage. Finally, a total of 22 cancer cases had cytogenetic samples that could be analyzed. Twenty-two control subjects were selected from those who did not develop cancer in the study period, and these subjects were matched to cases by sex, age, smoking habits, and residential area. The results showed that there was no significant difference in the frequencies of SCE and chromatid-type CAs between the case and control groups. However, the frequencies of chromosome-type CAs, e.g., chromosome-type gaps, chromosome-type breaks, chromosome-type breaks plus exchanges, total chromosome-type aberrations, and total frequencies of CAs in the case group, were significantly higher than those in the control group (P < 0.05). The odds ratio of cancer risk in subjects with more than zero chromosome-type breaks was 5.0 (95% confidence interval = 1.09-22.82) compared to those with zero chromosomal breaks. The odds ratios for more than zero chromosome-type breaks plus exchanges and a frequency of total chromosome-type aberrations of >1.007% were 11.0 and 12.0, respectively (P < 0.05). Subjects with a total CA frequency of >4.023% had a 9-fold increase for cancer risk. These results indicate that chromosome-type CAs are good biomarkers for the prediction of cancer development, whereas SCEs and chromatid-type CAs cannot predict cancer risk.",
Arsenic,2343510,"Screening of plant growth-promoting traits in arsenic-resistant bacteria isolated from agricultural soil and their potential implication for arsenic bioremediation Abstract: Twelve arsenic (As)-resistant bacteria (minimum inhibitory concentration ranging from 10 to 30mM and 150 to 320mM for As(III) and As(V), respectively) were isolated from the agricultural soil of the Chianan Plain in southwestern Taiwan using enrichment techniques. Eight isolates capable of oxidizing As(III) (rate of oxidation from 0.029 to 0.059?Mh(-1) 10(-9) cell) and exhibiting As(III)-oxidase enzyme activity belong to Pseudomonas, Acinetobacter, Klebsiella and Comamonas genera, whereas four isolates that did not show As(III)-oxidizing activity belong to Geobacillus, Bacillus, Paenibacillus, and Enterobacter genera. Assessment of the parameters of plant growth promotion revealed that Pseudomonas sp. ASR1, ASR2 and ASR3, Geobacillus sp. ASR4, Bacillus sp. ASR5, Paenibacillus sp. ASR6, Enterobacter sp. ASR10 and Comamonas sp. ASR11, and ASR12 possessed some or all of the studied plant growth-promoting traits, including phosphate-solubilization, siderophore, IAA-like molecules and ACC deaminase production. In addition, the ability of As-resistant isolates to grow over wide ranges of pH and temperatures signify their potential application for sustainable bioremediation of As in the environment.",
Arsenic,888804,"Acetaminophen increases the risk of arsenic-mediated development of hepatic damage in rats by enhancing redox-signaling mechanism Abstract: We evaluated whether the commonly used analgesic-antipyretic drug acetaminophen can modify the arsenic-induced hepatic oxidative stress and also whether withdrawal of acetaminophen administration during the course of long-term arsenic exposure can increase susceptibility of liver to arsenic toxicity. Acetaminophen was co-administered orally to rats for 3 days following 28 days of arsenic pre-exposure (Phase-I) and thereafter, acetaminophen was withdrawn, but arsenic exposure was continued for another 28 days (Phase-II). Arsenic increased lipid peroxidation and reactive oxygen species (ROS) generation, depleted glutathione (GSH), and decreased superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione reductase (GR) activities. Acetaminophen caused exacerbation of arsenic-mediated lipid peroxidation and ROS generation and further enhancement of serum alanine aminotransferase and aspartate aminotransferase activities. In Phase-I, acetaminophen caused further GSH depletion and reduction in SOD, catalase, GPx and GR activities, but in Phase-II, only GPx and GR activities were more affected. Arsenic did not alter basal and inducible nitric oxide synthase (iNOS)-mediated NO production, but decreased constitutive NOS (cNOS)-mediated NO release. Arsenic reduced expression of endothelial NOS (eNOS) and iNOS genes. Acetaminophen up-regulated eNOS and iNOS expression and NO production in Phase-I, but reversed these effects in Phase-II. Results reveal that acetaminophen increased the risk of arsenic-mediated hepatic oxidative damage. Withdrawal of acetaminophen administration also increased susceptibility of liver to hepatotoxicity. Both ROS and NO appeared to mediate lipid peroxidation in Phase-I, whereas only ROS appeared responsible for peroxidative damage in Phase-II. © 2011 Wiley-Liss, Inc. Environ Toxicol, 2011.",
Arsenic,628466,"Increased mortality associated with well-water arsenic exposure in Inner Mongolia, China Abstract: We conducted a retrospective mortality study in an Inner Mongolian village exposed to well water contaminated by arsenic since the 1980s. Deaths occurring between January 1, 1997 and December 1, 2004 were classified according to underlying cause and water samples from household wells were tested for total arsenic. Heart disease mortality was associated with arsenic exposure, and the association strengthened with time exposed to the water source. Cancer mortality and all-cause mortality were associated with well-water arsenic exposure among those exposed 10-20 years. This is the first study to document increased arsenic-associated mortality in the Bayingnormen region of Inner Mongolia.",
Arsenic,628695,"Aurora-A overexpression associates with Ha-ras codon-12 mutation and blackfoot disease endemic area in bladder cancer Abstract: Our data revealed that 59.4% of the bladder cancer specimens showed Aurora-A overexpression, of which 31.8% also had Ha-ras codon-12 mutation; 45.5% were from blackfoot-disease endemic areas in which arsenic exposure is a major environment factor associated with various cancer formation. We further demonstrated that arsenic treatment of the immortalized bladder cell line, E7, increased Aurora-A expression. All together, co-existence of Aurora-A overexpression and Ha-ras mutation suggests a possible additively effect on the tumorigenesis of bladder cancer. In addition, Aurora-A overexpression and up-regulated by arsenic exposure opens a new direction for exploring the occurrence of bladder cancer occurrence in Taiwan.",
Arsenic,1015729,"Assessing element-specific patterns of bioaccumulation across New England lakes Abstract: Little is known about differences among trace elements in patterns of bioaccumulation in freshwater food webs. Our goal was to identify patterns in bioaccumulation of different elements that are large and consistent enough to discern despite variation across lakes. We measured methylmercury (MeHg) and trace element (As, Cd, Hg, Pb, and Zn) concentrations in food web components of seven New England lakes on 3-5 dates per lake, and contrasted patterns of bioaccumulation across lakes, metals and seasons. In each lake, trace element concentrations were compared across trophic levels, including three size fractions of zooplankton, planktivorous fish, and piscivorous fish. The trophic position of each food web component was estimated from N isotope analysis. Trace element concentrations varied widely among taxa, lakes and sampling dates. Yet, we identified four consistent patterns of bioaccumulation that were consistent across lakes: (1) MeHg concentration increased (i.e., was biomagnified) and Pb concentration decreased (i.e., was biodiminished) with increased trophic position. (2) Zinc concentration (as with MeHg) was higher in fish than in zooplankton, but overall variation in Zn concentration (unlike MeHg) was low. (3) Arsenic and Cd concentrations (as with Pb) were lower in fish than in zooplankton, but (unlike Pb) were not significantly correlated with trophic position within zooplankton or fish groups. (4) Average summer concentrations of As, Pb, Hg, and MeHg in zooplankton significantly predicted their concentrations in either planktivorous or piscivorous fish. Our secondary goal was to review sampling approaches in forty-five published studies to determine the extent to which current sampling programs facilitate cross-lake and cross-study comparisons of bioaccumulation. We found that studies include different components of the food web and sample too infrequently to enable strong cross-lake and cross-study comparisons. We discuss sampling strategies that would improve our capacity to identify consistent patterns of bioaccumulation and drivers of elevated trace element concentrations under naturally high levels of variability.",
Arsenic,628432,"Association of arsenic-induced malignant transformation with DNA hypomethylation and aberrant gene expression Abstract: Inorganic arsenic, a human carcinogen, is enzymatically methylated for detoxication, consuming S-adenosyl-methionine (SAM) in the process. The fact that DNA methyltransferases (MeTases) require this same methyl donor suggests a role for methylation in arsenic carcinogenesis. Here we test the hypothesis that arsenic-induced initiation results from DNA hypomethylation caused by continuous methyl depletion. The hypothesis was tested by first inducing transformation in a rat liver epithelial cell line by chronic exposure to low levels of arsenic, as confirmed by the development of highly aggressive, malignant tumors after inoculation of cells into Nude mice. Global DNA hypomethylation occurred concurrently with malignant transformation and in the presence of depressed levels of S-adenosyl-methionine. Arsenic-induced DNA hypomethylation was a function of dose and exposure duration, and remained constant even after withdrawal of arsenic. Hyperexpressibility of the MT gene, a gene for which expression is clearly controlled by DNA methylation, was also detected in transformed cells. Acute arsenic or arsenic at nontransforming levels did not induce global hypomethylation of DNA. Whereas transcription of DNA MeTase was elevated, the MeTase enzymatic activity was reduced with arsenic transformation. Taken together, these results indicate arsenic can act as a carcinogen by inducing DNA hypomethylation, which in turn facilitates aberrant gene expression, and they constitute a tenable theory of mechanism in arsenic carcinogenesis.",
Arsenic,2347653,"Biomonitoring of heavy metals (Cd, Hg, and Pb) and metalloid (As) with the Portuguese common buzzard (Buteo buteo) Abstract: The accumulation of heavy metals in the environment may have a wide range of health effects on animals and humans. Thus, in this study, the concentrations of arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) in the blood and tissues (liver and kidney) of Portuguese common buzzards (Buteo buteo) were determined by inductively coupled plasma-mass spectrometer (ICP-MS) in order to monitor environmental pollution to these elements. In general, Hg and As were the elements which appeared in the highest and lowest concentrations, respectively. A highest percentage of non-detected concentration was found for blood Cd (94.6 %) but, in turn, it was the only metal that was detected in all kidney samples. The kidney was the analyzed sample which showed the highest concentrations of each element evaluated. Statistically, significant differences among blood, liver, and kidney samples were observed for As and Cd (P?&lt;?0.05). Cd concentrations in kidney and liver varied significantly with age: Adults showed higher hepatic and renal Cd concentrations than juveniles. Blood Pb concentration seems to show an association with the hunting season. Although raptors are at the top of the food chain and are thus potentially exposed to any biomagnification processes that may occur in a food web, the individuals evaluated in this study generally had low levels of heavy metals in blood and tissues. However, chronic exposure to these metals was verified. The results presented here lend weight to arguments in favor of continuous biomonitoring of metals and metalloids, since heavy metals may accumulate to levels that will pose a risk to both human health and the environment.",
Arsenic,1347574,"Arsenic contamination in drinking water of tube wells in Bangladesh: Statistical analysis and associated factors Abstract: Recently arsenic contamination in tubewell water is of a growing concern among the policy makers and researchers. This study has been devoted to the investigation of the existing arsenic contamination level in tubewell water and as well as the association among different characteristics of tubewells of two-selected regions of Bangladesh. The data were collected from a highly arsenic contaminated area at Chuddyagram Upazila in Comilla district and from a low arsenic contaminated area at Modhupur Upazila in Tangail district. More than two third of the tubewells of that region are private and 53.3% of the tubewells have been installed in the last ten years. 27.1% of the tubewells were found to be used by 11-20 persons regularly. Around 35.9% of the tubewells were completely unaffected by arsenic. About 68.8% of the tubewells have been installed above 30 m depth level. Among the tubewells under study 66.3% were found to be marked as safe. Among the users of the tubewells, 25.7% were found to be under risk of arsenic pollution by tubewell water. Most of the government tubewells (83.8%) are safe, whereas 58% of the private tubewells are arsenic free. Multiple linear regression analysis suggested that both the depth and age of installation of tubewells have significant negative impacts on the level of arsenic. Number of users was found to be significantly influenced by depth and age of installation in positive direction and by arsenic contamination level in negative direction. Linear logistic regression has been used to identify the factors that significantly affect the status of a tubewells to be identified as arsenic contaminated and only depth level of tubewells was found to have significant negative effect on the dependent variable. Finally, on the basis of the findings a set of recommendations have been suggested in this article, which will help the policy makers to take future initiatives to overcome the problem.",
Arsenic,1508644,"Perioperative and late clinical outcomes of 105 percutaneous transluminal stentings of the celiac and superior mesenteric arteries over the past decade Abstract: BACKGROUND: Several authorities have proposed stenting of the superior mesenteric artery (SMA)/celiac artery (CA) as the primary treatment for patients with chronic mesenteric ischemia. However, most of these reports had small samples and short follow-up periods. METHODS: Eighty-three patients were treated over a 10-year period. Clinical follow-up and duplex ultrasound exams were done to evaluate long-term patency. We used our newly validated duplex criteria to detect ?70% in-stent stenosis of the SMA and CA. A Kaplan-Meier life-table analysis was used to estimate freedom from in-stent stenosis and late symptom and survival rates. RESULTS: Fifty-four SMA and 51 CA stents were analyzed. The initial technical and clinical success rates were 97% and 96%, respectively, with 2% procedure morbidity and 2% mortality. The primary late clinical success rate was 59%, and the late ?70% in-stent stenosis rate was 51% at a mean follow-up of 31 months (range, 1-124). Freedom from late recurrent symptoms at 1, 2, 3, 4, and 5 years was 83, 77, 70, 70, and 65%, respectively. Survival rates at the same intervals were 88%, 82%, 70%, 64%, and 51%. Primary patency rates for the whole series were 69%, 48%, 39%, 28%, and 19% at 1, 2, 3, 4, and 5 years, respectively. Assisted primary patency rates for the whole series were 80%, 61%, 54%, 43%, and 34% at 1, 2, 3, 4, and 5 years, respectively. Primary patency rates for the SMA at 1, 2, 3, 4, and 5 years were 71%, 47%, 37%, 28%, and 18%, respectively; and assisted primary rates were 82%, 64%, 57%, 45%, and 32%, respectively. Primary patency rates for the CA were 68%, 50%, 40%, 29%, and 21%; and assisted primary rates were 79%, 58%, 52%, 42%, and 36% for 1, 2, 3, 4, and 5 years, respectively. There were no significant differences in either primary or assisted primary patency between the SMA and CA (P = .7729 and .8169). A secondary intervention was carried out in 30% of the series. Freedom from ?70% in-stent stenosis for the SMA was 82%, 65%, 56%, 42%, and 34%, and that for the CA was 73%, 59%, 48%, 34%, and 25%, at 1, 2, 3, 4, and 5 years, respectively. CONCLUSIONS: Stenting of SMA/CA stenosis has high technical/early clinical success rates with a satisfactory late clinical outcome; however, it is associated with high rates of late in-stent stenosis and intervention.",
Arsenic,1033465,"Cell cycle-specific effects of sodium arsenite and hyperthermic exposure on incorporation of radioactive leucine and phosphate by stress proteins from mouse lymphoma cell nuclei Abstract: Cultured mouse lymphoma cells incorporated [3H]leucine and [32P]phosphate into nuclear stress proteins within 3 h after exposure to either elevated temperature (45 degrees C) or sodium arsenite. Radiolabeled proteins were detected by autoradiography after two-dimensional polyacrylamide gel electrophoresis. To determine the cell cycle stage specificity of labeling, nuclei were isolated and sorted into two cell cycle phases using a fluorescent activated cell sorter. After either heat shock or sodium arsenite treatment, the majority of [3H]leucine incorporation into stress proteins occurred during the G0 + G1 phase with minimal labeling in the G2 phase. On the other hand, 32P labeling of stress proteins occurred in both the G0 + G1 and G2 phases after exposure to sodium arsenite, while incorporation of 32P was limited after heat stress. Following sodium arsenite treatment, a distinct set of four stress proteins (80-84 kDa) was detected with [3H]leucine only in G0 + G1 phase, but with [32P]phosphate these stress proteins were labeled in both G0 + G1 and G2. There was differential [32P]phosphate labeling between proteins of the 80-84 kDa set during cell cycling. Individual proteins of this set were isolated from gel plugs after sodium arsenite or heat-shock treatment. Coelectrophoresis of proteins from the two treatment groups showed that they had similar electrophoretic mobilities. All four proteins of the 80-84 kDa set (sodium arsenite induced) possessed similar polypeptide maps after digestion with V8 protease. Cytofluorometric analysis demonstrated a reduction in the number of nuclei in both S and G2 phases of the cell cycle two h after heat shock, but not following sodium arsenite treatment. However, there was a significant depression in the number of nuclei in S and G2 4 h after exposure to sodium arsenite and very modest labeling with 32P of stress proteins was observed at this time.",
Arsenic,2345667,"Metabolites and metals in Metazoa - What role do phytochelatins play in animals? Abstract: Phytochelatins are sulfur-rich metal-binding peptides, and phytochelatin synthesis is one of the key mechanisms by which plants protect themselves against toxic soft metal ions such as cadmium. It has been known for a while now that some invertebrates also possess functional phytochelatin synthase (PCS) enzymes, and that at least one species, the nematode Caenorhabditis elegans, produces phytochelatins to help detoxify cadmium, and probably also other metal and metalloid ions including arsenic, zinc, selenium, silver, and copper. Here, we review recent studies on the occurrence, utilization, and regulation of phytochelatin synthesis in invertebrates. The phytochelatin synthase gene has a wide phylogenetic distribution, and can be found in species that cover almost all of the animal tree of life. The evidence to date, though, suggests that the occurrence is patchy, and even though some members of particular taxonomic groups may contain PCS genes, there are also many species without these genes. For animal species that do possess PCS genes, some of them (e.g. earthworms) do synthesize phytochelatins in response to potentially toxic elements, whereas others (e.g. Schistosoma mansoni, a parasitic helminth) do not appear to do so. Just how (and if) phytochelatins in invertebrates complement the function of metallothioneins remains to be elucidated, and the temporal, spatial, and metal specificity of the two systems is still unknown.",
Arsenic,2278609,"A web-accessible computer program for calculating electrical potentials and ion activities at cell-membrane surfaces Abstract: Increasing evidence indicates that plant responses to ions (uptake/transport, inhibition, and alleviation of inhibition) are dependent upon ion activities at the outer surface of root-cell plasma membranes (PMs) rather than activities in the bulk-phase rooting medium. <br> <br>A web-accessible computer program was written to calculate the electrical potential (psi) at the outer surface of root-cell PMs (psi (PM)). From these values of psi (PM), activities of ion I with charge Z ({I (Z)}) can be calculated for the outer surface of the PM ({I (Z)}(PM)). In addition, psi and {I (Z)} in the Donnan phase of the cell walls (psi (CW) and {I (Z)}(CW)) can be calculated. <br> <br>By reanalysing published data, we illustrate how this computer program can assist in the investigation of plant-ion interactions. For example, we demonstrate that in saline solutions, both Ca deficiency and Na uptake are more closely related to {Ca2+}(PM) and {Na+}(PM) than to {Ca2+}(b) and {Na+}(b) (activities in the bulk-phase media). Additional examples are given for Zn and P nutrition, Ni toxicity, and arsenate uptake. <br> <br>The computer program presented here should assist others to develop an electrostatic view of plant-ion interactions and to re-evaluate some commonly-held views regarding mechanisms of ion transport, toxicity, competition among ions, and other phenomena.",
Arsenic,2337142,"Participatory multi-criteria evaluation of alternative options for water supply in cyclone-prone areas of Bangladesh Abstract: Availability of safe drinking water is considered a key challenge in the coastal region of Bangladesh. High concentrations of salinity, iron and arsenic, and the unavailability of suitable aquifers, have deterred the exploitation of groundwater resources. In addition the cyclonic storm surge is a major threat to this system. Cyclones accompanied by storm surges in the coastal area cause significant deterioration of drinking water supply and sanitation. Water professionals have launched some initiatives to promote small-scale, alternative safe water sources (e. g. rainwater harvesting, pond sand filters and piped water techniques) to provide sustainable solutions to the problem. However, a systematic evaluation of the alternatives that considers social, technical and economic criteria has not been carried out so far. The present study is an attempt to evaluate the alternative options for drinking water supply in a cyclone-prone area. The authors conducted a multi-criteria analysis and reached the conclusion that rainwater harvesting is the most suitable option for the area. Moreover, the final result was shared with the users to obtain their feedback to ensure sustainability of the water source.",
Arsenic,1337538,"Fibroblast growth factor 21 is induced by endoplasmic reticulum stress Abstract: Increased hepatic expression is held responsible for elevated serum levels of fibroblast growth factor 21 (FGF21) in non-alcoholic fatty liver disease (NAFLD) but the underlying molecular mechanism is unclear. In the present study we tested the postulate that the metabolic hormone FGF21 is regulated by endoplasmic reticulum (ER) stress, a condition that is observed in a number of diseases including NAFLD and results in activation of an adaptive response known as the unfolded protein response (UPR). ER stress stimuli were found to induce expression of Fgf21 mRNA in H4IIE hepatoma cells and in isolated rat hepatocytes. Moreover, intraperitoneal injection of the ER stressor tunicamycin induced hepatic Fgf21 expression in mice and resulted in marked elevation of serum FGF21 levels. The effect of ER stress on FGF21 expression could be mimicked by overexpression of ATF4, a transcriptional effector of the PERK-branch of the UPR. In silico analysis revealed the presence of two binding sites for ATF4 in the FGF21 promoter region. Combined disruption of these elements, abrogated FGF21 promoter activity induced by ER stress or ATF4 overexpression. These findings implicate the PERK/eIF2alpha/ATF4 cascade in ER stress regulation of FGF21. A consequence of this notion is that other intracellular stress signaling pathways that converge at eIF2alpha, can regulate FGF21 expression. Indeed, both nutrient (amino acid deprivation) and oxidative stress (arsenite) were found to induce Fgf21 expression in hepatoma cells and isolated rat hepatocytes. In conclusion, FGF21 expression is regulated by ER stress and additional intracellular stress signaling pathways. Our findings suggest that increased cellular stress in fatty livers may underlie the elevated FGF21 levels observed in patients with NAFLD.",
Arsenic,1015777,"Potential Health Risk of Total Arsenic from Consumption of Farm Rice (Oryza sativa) from the Southern Caspian Sea Littoral and from Imported Rice in Iran Abstract: In this study, Arsenic (As) was measured in several varieties of imported and local cultivated rice. Soil samples collected from rice farms situated in south Caspian Sea (Iran) were also studied. The mean concentration of As in imported rice, local farmed rice and soil, were determined as 0.28, 0.39 and 3.80 ?g g(-1) dry weight, respectively. Estimated daily intake of As through human consumption of imported and local produced rice was 0.77 and 1.074 ?g day(-1) kg(-1) B.W., respectively. These values are much lower than the tolerable daily intakes estimated by JECFA. The As concentration in the soil (3.80 ?g g(-1) dry) was below acceptable limit for agricultural soil of 20.0 mg kg(-1) as recommended by the European Community (EC). No correlation between the As concentrations in rice and soil samples was found (p &gt; 0.05).",
Arsenic,627973,"Modification of risk of arsenic-induced skin lesions by sunlight exposure, smoking, and occupational exposures in Bangladesh Abstract: BACKGROUND: The risk of skin lesions associated with arsenic exposure from drinking water in Bangladesh is considerably greater in men than in women. METHODS: Using baseline data from 11,062 cohort members in the Health Effects of Arsenic Longitudinal Study in Araihazar, Bangladesh, we performed a cross-sectional analysis to evaluate whether the association between arsenic exposure from drinking water and the risk of skin lesions is modified by tobacco smoking, excessive sunlight, the use of fertilizer, and the use of pesticides. A time-weighted well arsenic concentration was estimated for each participant by incorporating history of well use. Relative excess risk for interaction (RERI) and its 95% confidence intervals (CIs) were estimated using adjusted prevalence odds ratios. RESULTS: We observed a synergistic effect between the highest level of arsenic exposure (> 113 microg/L) and tobacco smoking on risk of skin lesions in men (RERI = 1.5 [95% CI = 0.3 to 2.7] overall and 1.7 [0.2 to 3.4] for the subpopulation with longer-term arsenic exposure). We also observed suggestive synergistic effects between higher levels (28.1-113.0 microg/L and 113.1-864.0 microg/L) of arsenic exposure and fertilizer use in men (RERI = 1.0 [-0.2 to 2.2] and 1.3 [-0.2 to 2.9] respectively). Furthermore, the risk of skin lesions associated with any given level of arsenic exposure was greater in men with excessive sun exposure. The patterns of effect estimates in women indicate similar-but-weaker interaction effects of arsenic exposure with tobacco smoking and fertilizer use. CONCLUSIONS: These findings help explain why the risk of arsenic-related skin lesions was much greater in men than in women in Bangladesh. Because most arsenic-induced skin cancers arise from these skin lesions, treatment and remediation plans should take into consideration these etiologic cofactors.",
Arsenic,1337522,"Arsenite tolerance is related to proportional thiolic metabolite synthesis in rice (Oryza sativa L.) Abstract: Thiol metabolism is the primary detoxification strategy by which rice plants tolerate arsenic (As) stress. In light of this, it is important to understand the importance of harmonised thiol metabolism with As accumulation and tolerance in rice plant. For this aim, tolerant (T) and sensitive (S) genotypes were screened from 303 rice (Oryza sativa) genotypes on exposure to 10 and 25 ?M arsenite (As(III)) in hydroponic culture. On further As accumulation estimation, contrasting (13-fold difference) T (IC-340072) and S (IC-115730) genotypes were selected. This difference was further evaluated using biochemical and molecular approaches to understand involvement of thiolic metabolism vis-a-vis As accumulation in these two genotypes. Various phytochelatin (PC) species (PC(2), PC(3) and PC(4)) were detected in both the genotypes with a dominance of PC(3). However, PC concentrations were greater in the S genotype, and it was noticed that the total PC (PC(2) + PC(3 )+ PC(4))-to-As(III) molar ratio (PC-SH:As(III)) was greater in T (2.35 and 1.36 in shoots and roots, respectively) than in the S genotype (0.90 and 0.15 in shoots and roots, respectively). Expression analysis of several metal(loid) stress-related genes showed significant upregulation of glutaredoxin, sulphate transporter, and ascorbate peroxidase in the S genotype. Furthermore, enzyme activity of phytochelatin synthase and cysteine synthase was greater on As accumulation in the S compared with the T genotype. It was concluded that the T genotype synthesizes adequate thiols to detoxify metalloid load, whereas the S genotype synthesizes greater but inadequate levels of thiols to tolerate an exceedingly greater load of metalloids, as evidenced by thiol-to-metalloid molar ratios, and therefore shows a phytotoxicity response.",
Arsenic,1508670,"Arsenic-transforming microbes and their role in biomining processes Abstract: It is well known that microorganisms can dissolve different minerals and use them as sources of nutrients and energy. The majority of rock minerals are rich in vital elements (e.g., P, Fe, S, Mg and Mo), but some may also contain toxic metals or metalloids, like arsenic. The toxicity of arsenic is disclosed after the dissolution of the mineral, which raises two important questions: (1) why do microorganisms dissolve arsenic-bearing minerals and release this metal into the environment in a toxic (also for themselves) form, and (2) How do these microorganisms cope with this toxic element? In this review, we summarize current knowledge about arsenic-transforming microbes and their role in biomining processes. Special consideration is given to studies that have increased our understanding of how microbial activities are linked to the biogeochemistry of arsenic, by examining (1) where and in which forms arsenic occurs in the mining environment, (2) microbial activity in the context of arsenic mineral dissolution and the mechanisms of arsenic resistance, (3) the minerals used and technologies applied in the biomining of arsenic, and (4) how microbes can be used to clean up post-mining environments.",
Arsenic,1016909,"Arsenic poisoning in groundwater: Health risk and geochemical sources in Bangladesh Abstract: Of the 2508 water samples analyzed in 10 districts of Bangladesh, 51%, on an average, contained arsenic levels of 0.05 to 2.50 mg/l. 95% of nail, 96% of hair, and 94% of urine samples contained arsenic above the normal level. Approximately 3.58 million people out of a total of 17.92 million who are drinking water containing arsenic levels &gt;0.20 mg/l are potentially exposed to high risk of health hazard. Eight thousand and five hundred arsenic patients are identified; they are suffering from various skin lesions, gangrene in leg, skin, lung, bladder, liver, and renal cancer. A big portion of the total population is highly vulnerable to various internal cancers. Lowest arsenic concentration in drinking water producing dermatological disease is found to be 0.103 mg/l. However, the exposure time to develop arsenicosis varies from case to case reflecting its dependence on arsenic level in drinking water and food, nutritional status, genetic variant of human being, and compounding factors. This study has determined the high intensity of fluorescent humic substances in drinking water containing elevated concentrations of arsenic and very low concentrations of heavy metals. The synergistic/antagonistic effect of fluorescent compounds present in drinking water may aggravate the toxicity of arsenic. Geochemical study suggests that arsenic may be released from both reductive dissolution of Fe and Mn (oxy)hydroxide and microbial oxidation of organic matter.",
Arsenic,1021547,"Dose-dependent urinary phenotype of inorganic arsenic methylation in mice with a focus on trivalent methylated metabolites Abstract: Inorganic arsenic (iAs) exposure has been associated with the increased risk of various forms of cancer and of non-cancerous diseases. Metabolic conversions of iAs that yield highly toxic and genotoxic methylarsonite (MAsIII) and dimethylarsinite (DMAsIII) may play a significant role in determining the extent and character of toxic and cancer-promoting effects of iAs exposure. However, in vivo research involving the production of MAsIII and DMAsIII remains an area of ongoing investigation and debate. The results of metabolic and toxicity studies using mice have been entirely applicable to other species including humans. The goal of this study was to investigate the phenotype for the trivalent and pentavalent arsenic metabolites in relation to arsenite dose via immediate analysis of fresh urine samples, while preventing the oxidation of unstable methylated AsIII-containing metabolites. Female mice (C57BL/6) received sodium arsenite by gavage at doses of 0, 3, 6 or 10?mg As/kg/day for 9 days, after which trivalent methylated arsenicals were detected in 100% of urine samples; these arsenicals were not detected in the urine of control mice. The amount of DMAsIII detected in urine depended on the dose of arsenite administered and was determined to be 50.2%, 31.4% and 16.5% of the total urinary arsenic in mice exposed to 3, 6, or 10?mg/kg/day, respectively. This relationship is consistent with the hypothesis of inhibition or saturation of iAs methylation. Understanding the in vivo production of MAsIII and DMAsIII in mice exposed to iAs could aid in developing a biologically based dose-response model for iAs.",
Arsenic,1018141,"Therapeutic efficacy of silymarin and naringenin in reducing arsenic-induced hepatic damage in young rats Abstract: We investigated the effects of silymarin and naringenin in counteracting arsenic-induced hepatic oxidative stress post exposure. Male wistar rats were chronically exposed to sodium arsenite for eight months followed by oral treatment with silymarin and naringenin (50 mg/kg each) for 15 consecutive days to evaluate hepatic damage and antioxidant potential. Our results demonstrate a significant decrease in hepatic GSH levels, SOD and catalase activities and an increase in GST and TBARS levels after arsenic administration. Silymarin or naringenin administration increased GSH levels and was beneficial in the recovery of altered SOD and catalase activity besides significantly reducing blood and tissue arsenic concentration. Our results point to the antioxidant potential of these flavonoids, which might be of benefit in the clinical recovery of subject exposed to arsenic. These flavonoids can be incorporated into the diet or co-supplemented during chelation treatment, and thus may afford a protective effect against arsenite-induced cytotoxicity.",
Arsenic,1519094,"Is saliva a potential biomarker of arsenic exposure? A case-control study in West Bengal, India Abstract: Saliva is a biological fluid that has not been used extensively as a biomonitoring tool in epidemiological studies. This study presents the arsenic (As) concentrations in saliva and urine samples collected from populations of West Bengal, India who had been previously exposed to high As levels in their drinking water. We found a significant (p < 0.05) association between the Log transformed Daily Ingestion of As (?g day(-1)) and the As concentration in saliva (r = 0.68). Additionally, As concentration of saliva and urine also had a significant positive correlation (r = 0.60, p < 0.05). Male participants, smokers, and cases of skin lesion were independently and significantly associated with an increase in salivary As. Thus our findings show that saliva is a useful biomarker of As exposure in the study population. The study also advocates that measurement of the forms of As in saliva may additionally provide insight into the internal dose and any individual differences in susceptibility to As exposure.",
Arsenic,2345646,"Geochemistry and microbial ecology in alkaline hot springs of Ambitle Island, Papua New Guinea Abstract: The availability of microbiological and geochemical data from island-based and high-arsenic hydrothermal systems is limited. Here, the microbial diversity in island-based hot springs on Ambitle Island (Papua New Guinea) was investigated using culture-dependent and -independent methods. Waramung and Kapkai are alkaline springs high in sulfide and arsenic, related hydrologically to previously described hydrothermal vents in nearby Tutum Bay. Enrichments were carried out at 24 conditions with varying temperature (45, 80 °C), pH (6.5, 8.5), terminal electron acceptors (O2, SO4 (2-), S(0), NO3 (-)), and electron donors (organic carbon, H2, As(III)). Growth was observed in 20 of 72 tubes, with media targeting heterotrophic metabolisms the most successful. 16S ribosomal RNA gene surveys of environmental samples revealed representatives in 15 bacterial phyla and 8 archaeal orders. While the Kapkai 4 bacterial clone library is primarily made up of Thermodesulfobacteria (74 %), no bacterial taxon represents a majority in the Kapkai 3 and Waramung samples (40 % Proteobacteria and 39 % Aquificae, respectively). Deinococcus/Thermus and Thermotogae are observed in all samples. The Thermococcales dominate the archaeal clone libraries (65-85 %). Thermoproteales, Desulfurococcales, and uncultured Eury- and Crenarchaeota make up the remaining archaeal taxonomic diversity. The culturing and phylogenetic results are consistent with the geochemistry of the alkaline, saline, and sulfide-rich fluids. When compared to other alkaline, island-based, high-arsenic, or shallow-sea hydrothermal communities, the Ambitle Island archaeal communities are unique in geochemical conditions, and in taxonomic diversity, richness, and evenness.",
Arsenic,1019130,"Monitoring of low level arsenic exposure during maintenance of ion implanters Abstract: To delineate potential exposure in ion implanter maintenance, the authors recruited 21 maintenance engineers (exposed group) and 10 computer programmers (controls) at three semiconductor manufacturing facilities. Samples of air, wipes, and urine; used cleaning cloths; and used gloves were collected for the characterization of arsenic exposure. Arsenic levels were very low in environmental samples, but high arsenic levels were found in some wipe samples, used cleaning cloths, and gloves. The average baseline content of urinary arsenic measured for maintenance engineers was 3.6 microg/g creatinine. Maintenance engineers experienced an increase of 1.0-7.8 microg/g creatinine in urinary arsenic levels during ion implanter maintenance. Results of a mixed-model analysis indicated that urinary arsenic levels were associated significantly with time series (p = .0001), and the extent of association was different among the three facilities (p = .0226). The results of this study indicate that arsenic intake via ingestion, rather than through inhalation, might play a significant role in the elevation of urinary arsenic levels. However, a series of urine samples with self-reference continue to be a good approach for the monitoring of low-level arsenic exposure.",
Arsenic,734916,"Distribution and speciation of arsenic after intravenous administration of monomethylmonothioarsonic acid in rats Abstract: Quite a few new thioarsenicals have recently been found in urine of arsenic-exposed humans and animals, and some of them have been shown to be highly toxic to cells. However, little is known about their toxic effects and metabolism in the body. In order to elucidate the toxic mechanism of thioarsenicals, we further focused on the distribution and metabolism of monomethylmonothioarsonic acid (MMMTA(V)) in rats. MMMTA(V) was synthesized chemically and injected intravenously into rats at the dose of 0.5mg As/kg, followed by speciation analysis of selected organs and body fluids at 10 min and 12h after the injection. MMMTA(V) was excreted into urine in its intact form, and approximately 35% of the dose was recovered in urine at 12h after the injection, suggesting that MMMTA(V) was taken up more effectively by organs/tissues than non-thiolated, monomethylarsonous acid (MMA(V)) previously studied. On the other hand, the liver and kidneys contained arsenic that was in a protein-binding form with free forms of DMA(V) or DMDTA(V) at 10 min, and disappeared at 12h after the injection. Moreover, these bound arsenic species in kidneys were converted back to MMA(V) after oxidation with H(2)O(2), suggesting that the arsenic bound to proteins had been reduced within the body and was in a trivalent oxidation state. In red blood cells (RBCs), most of the arsenic was in the form of DMA(III) bound to hemoglobin (Hb), and approximately 40% of the dose was recovered in RBCs at 12h after injection. These results indicate that arsenic accumulated preferentially in RBCs after being transformed to DMA(III). In addition, we have also discussed the effect of MMMTA(V) on viability of human bladder cancer T24 cells in comparison with MMA(V). Consequently, MMMTA(V) was assumed to be a more toxic arsenic metabolite than non-thiolated MMA(V).",
Arsenic,1519076,"Transmetalation of chromocene by lithium-amide, -phosphide, and -arsenide nucleophiles Abstract: The pnictogen-centered nucleophiles LiE(SiMe3)2 (E = N, P, or As) substitute a cyclopentadienide ligand of chromocene (Cp2Cr), with elimination of lithium cyclopentadienide, to give the series of pnictogen-bridged compounds [(?:?(2):?(5)-Cp)Cr{?-N(SiMe3)2}2Li] (1) and [(?(5)-Cp)Cr{?-E(SiMe3)2}]2, with E = P (2) or E = As (3). Whereas 1 is a heterobimetallic coordination polymer, 2 and 3 are homometallic dimers, with the differences being due to a structure-directing influence of the hard or soft character of the bridging group 15 atoms. For compound 1, the experimental magnetic susceptibility data were accurately reproduced by a single-ion model based on high-spin chromium(II) (S = 2), which gave a g-value of 1.93 and an axial zero-field splitting parameter of D = -1.83 cm(-1). Determinations of phosphorus- and arsenic-mediated magnetic exchange coupling constants, J, are rare: in the dimers 2 and 3, variable-temperature magnetic susceptibility measurements identified strong antiferromagnetic exchange between the chromium(II) centers, which was modeled using the spin Hamiltonian H = -2J(SCrA·SCrB), and produced large coupling constants of J = -166 cm(-1) for 2 and -77.5 cm(-1) for 3.",
Arsenic,1519067,"Arsenic tolerance, uptake, and accumulation by nonmetallicolous and metallicolous populations of Pteris vittata L Abstract: Although it is known that the first As hyperaccumulator identified, Pteris vittata L., could exist in As-contaminated as well as uncontaminated soils, intra-specific variation in As accumulation among metallicolous (from As-contaminated soils) and nonmetallicolous populations (from uncontaminated soils) of P. vittata has not been fully explored. Variations in As concentrations of fronds were observed in three nonmetallicolous populations and four metallicolous populations of P. vittata collected from southeast China. The kinetics study showed that the concentration-dependent influx of arsenate and arsenite observed followed Michaelis-Menten kinetics, and that the average V max for arsenate and arsenite was apparently larger in the three nonmetallicolous populations than that in the three metallicolous populations. The pot trials indicated that the nonmetallicolous populations had significantly (p?&lt;?0.05) higher frond biomass, about 1.5-1.9-folds, when compared with the metallicolous populations in 250 and 500 mg As kg(-1) soil treatments. The pot trials also demonstrated that the nonmetallicolous population of P. vittata had a significantly higher accumulation and translocation capacity for As. The present study suggests that As removal by P. vittata can be greatly enhanced by the judicious selection of the appropriate populations.",
Arsenic,2347650,"Rat subcutaneous tissue response to calcium silicate containing different arsenic concentrations Abstract: Objective: To evaluate the response of rat subcutaneous tissue in implanted polyethylene tubes that were filled with GMTA Angelus and Portland cements containing different arsenic concentrations. Material and Methods: Atomic absorption spectrophotometry was utilized to obtain the values of the arsenic concentration in the materials. Thirty-six rats were divided into 3 groups of 12 animals for each experimental period. Each animal received two implants of polyethylene tubes filled with different test cements and the lateral of the tubes was used as a control group. After 15, 30 and 60 days of implantation, the animals were killed and the specimens were prepared for descriptive and morphometric analysis considering: inflammatory cells, collagen fibers, fibroblasts, blood vessels and other components. The results were analyzed utilizing the Kuskal-Wallis test and the Dunn's Multiple test for comparison (p&lt;0.05). Results: The materials showed, according to atomic absorption spectrophotometry, the following doses of arsenic: GMTA Angelus: 5.01 mg/kg, WPC Irajazinho: 0.69 mg/kg, GPC Minetti: 18.46 mg/kg and GPC Votoran: 10.76 mg/kg. In a 60-day periods, all specimens displayed a neoformation of connective tissue with a structure of fibrocellular aspect (capsule). Control groups and MTA Angelus produced the lower amount of inflammatory reaction and GPC Minetti, the highest reaction. Conclusions: There was no direct relationship between the concentration of arsenic present in the composition of the materials and the intensity of the inflammatory reactions. Higher values, as 18.46 mg/kg of arsenic in the cement, produce characteristics of severe inflammation reaction at the 60-day period. The best results were found in MTA angelus.",
Arsenic,1240154,"Removal of Arsenic from Aqueous Solutions by Sorption onto Sewage Sludge-Based Sorbent Abstract: This study aimed at evaluating and comparing the removal of arsenic from solutions by a low-cost waste-based sorbent, produced by pyrolysing sewage sludge under appropriate conditions, and by a commercially activated carbon. Batch sorption experiments were performed under isothermal conditions (20 degree C), in order to evaluate the effect of pH on the arsenic sorption kinetics and on the equilibrium sorption capacity of the materials under study. Kinetic data revealed that the arsenic sorption was faster onto the activated carbon than onto the pyrolysed sludge. The sorption process was well described by both the pseudo-first and pseudo-second-order kinetics equations for both materials. Changes in the initial solution pH have distinct effects on the removal of arsenic onto pyrolysed sludge and activated carbon. While for pyrolysed sludge, pH affects essentially the equilibrium time, for activated carbon it affects the sorption capacity. Equilibrium results were well described by both Freundlich and Langmuir isotherm models, although fittings corresponding to the Langmuir isotherm were slightly better. The Langmuir maximum sorption capacity determined for the pyrolysed sludge was 71 mu g g super(-1), while for activated carbon was 229 mu g g super(-1). Despite the relative lower capacity of the pyrolysed sludge, the considerable lower cost and the valorisation of the sludge may justify further research on its use for water decontamination.",
Arsenic,2347585,"Vitamin D deficiency in anesthesia department caregivers at the end of winter Abstract: <strong>BACKGROUND: </strong>To test whether the vitamin D status of anesthesia department caregivers practicing at high Northern latitudes is compatible with current recommendations, the 25-hydroxyvitamin D (25(OH)D) levels of caregivers at hospitals in Iceland (64°08' N) and in Wisconsin (43°07' N) were compared at the end of winter.<br /><br /><strong>METHODS: </strong>Anesthesia department faculty and resident physicians, non-physician anesthetists, and critical care nurses completed a questionnaire, and provided blood samples for analysis of 25(OH)D by reverse-phase high performance liquid chromatography.<br /><br /><strong>RESULTS: </strong>One hundred and six participants in Iceland and 124 participants in Wisconsin were enrolled. No difference in mean serum 25(OH)D levels between Iceland [70.53?nmol/l, standard deviation (SD) 30.87?nmol/l] and Wisconsin (70.0?nmol/l, SD 30.0?nmol/l) was observed. In Iceland and Wisconsin, 25(OH)D levels below 25?nmol/l were observed in 4.7% and 4.0%, below 50?nmol/l in 34.9% and 25.0%, and below 75?nmol/l in 56.6% and 61.3% of caregivers, respectively.<br /><br /><strong>CONCLUSIONS: </strong>25(OH)D levels below the 50?nmol/l (20?ng/ml) threshold recommended by the Institute of Medicine and the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis, and below the 75?nmol/l (30?ng/ml) threshold recommended by The Endocrine Society, are highly prevalent among anesthesia caregivers working at two Northern hospitals at the end of winter who may otherwise not meet criteria to be tested. Anesthesia and critical care providers may wish to determine their 25(OH)D levels and use effective, safe, and low cost supplementation to target a 25(OH)D level compatible with optimal health.",
Arsenic,2337248,"Serum arsenic and lipid peroxidation levels in patients with multiple sclerosis Abstract: Oxidative stress plays a crucial role in the pathogenesis of multiple sclerosis (MS). Previous studies have shown that oxidative stress is one of the main underlying mechanisms of arsenic-induced cellular damage. The aim of this study was to assess the serum levels of arsenic and its relationship with lipid peroxidation in MS patients from Tabriz, as the third polluted city of Iran. The study population included 38 MS female patients and 38 age-matched healthy controls. Serum malondialdehyde (MDA) and arsenic levels were measured using thiobarbituric acid reactive substances (TBARS) assay and electrothermal atomic absorption spectrometry, respectively. The results showed that the arsenic (P?&lt;?0.01) and MDA (P?=?0.03) levels were significantly higher in patients with MS than those in control. Moreover, serum levels of arsenic and MDA were positively correlated in MS patients. The elevated levels of serum arsenic might explain the increased oxidative stress in MS patients. We suggest that high arsenic levels in serum may lead to MS development, and therefore, exposure to this metal should be limited.",
Arsenic,628127,"Risk of internal cancers from arsenic in drinking water Abstract: The U.S. Environmental Protection Agency is under a congressional mandate to revise its current standard for arsenic in drinking water. We present a risk assessment for cancers of the bladder, liver, and lung from exposure to arsenic in water, based on data from 42 villages in an arseniasis-endemic region of Taiwan. We calculate excess lifetime risk estimates for several variations of the generalized linear model and for the multistage-Weibull model. Risk estimates are sensitive to the model choice, to whether or not a comparison population is used to define the unexposed disease mortality rates, and to whether the comparison population is all of Taiwan or just the southwestern region. Some factors that may affect risk could not be evaluated quantitatively: the ecologic nature of the data, the nutritional status of the study population, and the dietary intake of arsenic. Despite all of these sources of uncertainty, however, our analysis suggests that the current standard of 50 microg/L is associated with a substantial increased risk of cancer and is not sufficiently protective of public health.",
Arsenic,1356759,Genotoxicity of arsenic and its methylated metabolites Abstract: ,
Arsenic,1508606,"Sulfate availability drives divergent evolution of arsenic speciation during microbially mediated reductive transformation of schwertmannite Abstract: The effect of SO42- availability on the microbially mediated reductive transformation of As(V)-coprecipitated schwertmannite ((Fe8O8OH)3.2(SO4)2.4(AsO4)0.004) was examined in long-term (up to 400 days) incubation experiments. Iron EXAFS spectroscopy showed siderite (FeCO3) and mackinawite (FeS) were the dominant secondary Fe(II) minerals produced via reductive schwertmannite transformation. In addition, ?25% to ?65% of the initial schwertmannite was also transformed relatively rapidly to goethite (?FeOOH), with the extent of this transformation being dependent on SO42- concentrations. More specifically, the presence of high SO42- concentrations acted to stabilize schwertmannite, retarding its transformation to goethite and allowing its partial persistence over the 400 day experiment duration. Elevated SO42- also decreased the extent of dissimilatory reduction of Fe(III) and As(V), instead favoring dissimilatory SO42- reduction. In contrast, where SO42- was less available, there was near-complete reduction of schwertmannite- and goethite-derived Fe(III) as well as solid-phase As(V). As a result, under low SO42- conditions, almost no Fe(III) or As(V) remained toward the end of the experiment and arsenic solid-phase partitioning was controlled mainly by sorptive interactions between As(III) and mackinawite. These As(III)-mackinawite interactions led to the formation of an orpiment (As2S3)-like species. Interestingly, this orpiment-like arsenic species did not form under SO42--rich conditions, despite the prevalence of dissimilatory SO42- reduction. The absence of an arsenic sulfide species under SO42--rich conditions appears to have been a consequence of schwertmannite persistence, combined with the preferential retention of arsenic oxyanions by schwertmannite. The results highlight the critical role that SO42- availability can play in controlling solid-phase arsenic speciation, particularly arsenic-sulfur interactions, under reducing conditions in soils, sediments, and shallow groundwater systems.",
Arsenic,1019363,"Expression of p53 in arsenic-related and sporadic basal cell carcinoma Abstract: <strong>BACKGROUND: </strong>The TP53 gene has been shown to have an important role in the genesis of sporadic, presumably mainly sunlight-related, basal cell carcinoma (BCC). However, its role in arsenic-related BCCs is not clear, although the trivalent form of arsenic has been long recognized as a cause of BCC. Arsenic treatment has been shown to cause hypermethylation of the TP53 gene in lung carcinoma cell lines, but it is not known if this occurs in vivo in arsenic-related BCCs.<br /><br /><strong>OBJECTIVE: </strong>To compare the immunohistochemical expression of the p53 protein in arsenic-related and sporadic BCCs to determine if the expression pattern is consistent with gene silencing.<br /><br /><strong>SETTING: </strong>A research institute and hospital in Australia.<br /><br /><strong>CASES: </strong>One hundred seventeen white patients with 121 sporadic BCCs and 21 white patients with 92 arsenic-related BCCs.<br /><br /><strong>MAIN OUTCOME MEASURES: </strong>The expression and the intensity of p53 were scored semiquantitatively. Statistical analysis was performed using the chi2 test.<br /><br /><strong>RESULTS: </strong>Arsenic-related BCCs express p53 less often and at a lower intensity than sporadic BCCs (P = .001; 2-tailed test). The BCCs from sun-exposed sites, whether arsenic related or sporadic, more frequently showed overexpression of p53 than those from less-exposed areas (P = .004; 2-tailed test). The more aggressive subtypes of BCC show a higher level of expression of p53 than the less aggressive forms (P = .04; 2-tailed chi2 test).<br /><br /><strong>CONCLUSIONS: </strong>These results are consistent with the hypothesis that the TP53 gene is down-regulated by methylation in arsenic-related BCC, particularly those from less-exposed sites. However, an alternative possibility is that mutations in TP53 that stabilize the protein are less common in arsenic-related BCCs. Further analysis will be necessary to distinguish between these hypotheses.",
Arsenic,1021523,"Surveillance on chronic arsenic exposure in the Mekong River basin of Cambodia using different biomarkers Abstract: Thousands of Cambodia populations are currently at high risks of both toxic and carcinogenic effects through drinking arsenic-rich groundwater. In order to determine and assess the use of arsenic contents in different biological samples as biomarkers of chronic arsenic exposure from drinking arsenic-rich groundwater in Cambodia, individual scalp hair, fingernail and toenail were collected from three different provinces in the Mekong River basin of Cambodia. After washing and acid-digestion, digestate was analyzed for total arsenic by an inductively coupled plasma mass spectrometry. Chemical analysis of the acid-digested hair revealed that among 270 hair samples cut from Kandal, 78.1% had arsenic content in scalp hair (As(h)) greater than the typical As(h) (1.00 ?g g(-1)), indicating possible arsenic toxicity. Concurrently, 1.2% and 0.6% were found elevated in Kratie (n=84) and Kampong Cham (n=173), respectively. Similarly, the upper end of the ranges for arsenic contents in fingernail (As(fn)) and toenail (As(tn)) clipped from Kandal (fingernail n=241; toenail n=187) were higher than the normal arsenic content in nail (0.43-1.08 ?g g(-1)), however, none was observed elevated in both Kratie (fingernail n=76, toenail n=42) and Kampong Cham (fingernail n=83; toenail n=52). Significant positive intercorrelations between groundwater arsenic concentration (As(w)), average daily dose (ADD) of arsenic, As(h), As(fn) and As(tn) suggest that As(h), As(fn) and As(tn) can be used as biomarkers of chronic arsenic exposure from drinking arsenic-rich groundwater, in which As(h) is more favorable than As(fn) and As(tn) due to the ease of sample processing and analytical measurements, respectively.",
Arsenic,537890,"Inhibition of mitogen-activated protein kinase kinase enhances apoptosis induced by arsenic trioxide in human breast cancer MCF-7 cells Abstract: 1. Arsenic trioxide (As2O3) has recently been used to treat acute promyelocytic leukaemia and has activity in vitro against several solid tumour cell lines where the induction of differentiation and apoptosis are the prime effects. The mechanism of As2O3-induced cell death has yet to be clarified, especially in solid cancers. 2. In the present study, the human breast cancer cell line MCF-7 was examined as a cellular model for As2O3 treatment. The involvement of extracellular signal-regulated kinase (ERK), p38 and c-Jun N-terminal kinase (JNK) was investigated in As2O3-induced cell death. 3. It was found that As2O3 activates the prosurvival mitogen-activated protein kinase kinase (MEK)/ERK pathway in MCF-7 cells, which, conversely, may compromise the efficacy of As2O3. Hence, a combination treatment of As2O3 and MEK inhibitors was investigated to determine whether this treatment could lead to enhanced growth inhibition and apoptosis in MCF-7 cells. 4. Inhibition of MEK/ERK with the pharmacological inhibitors U0126 (10 mu mol/L) or PD98059 (20 mu mol/L) together with As2O3 (2 and 5 mu mol/L) resulted in a significant enhancement of growth inhibition in breast cancer MCF-7 cells as determined by the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay and [Methyl-H-3]-thymidine incorporation. Furthermore, the results demonstrated that combined treatment with As2O3 and the MEK1/2 inhibitor U0126 could augment breast cancer MCF-7 cell apoptosis approximately twofold compared with the effects of the two drugs alone, as determined by Hoechst 33258 or annexin V/propidium iodide (PI) staining and flow cytometry. 5. In addition, As2O3 activated p38 in a dose-dependent manner, but had no effect on JNK1/2. Treatment with a p38 inhibitor did not prevent As2O3-induced apoptosis. 6. In conclusion, the results of the present study showed that enhanced apoptosis is detected in breast cancer MCF-7 cells in the presence of As2O3 and an MEK inhibitor, which may be a new promising adjuvant to current breast cancer treatments.",
Arsenic,1350393,"Teratogen-induced cell death in postimplantation mouse embryos: differential tissue sensitivity and hallmarks of apoptosis Abstract: Teratogen-induced cell death is a common event in the pathogenesis associated with tissues destined to be malformed. Although the importance of this cell death is recognized, little information is available concerning the biochemistry of teratogen-induced cell death. We show that three teratogens, hyperthermia, cyclophosphamide and sodium arsenite induce an increase in cell death in day 9.0 mouse embryos with concurrent induction of DNA fragmentation, activation of caspase-3 and the cleavage of poly (ADP-ribose) polymerase (PARP). Teratogen-induced cell death is also selective, i. e., some cells within a tissue die while others survive. In addition, cells within some tissues die when exposed to teratogens while cells in other tissues are relatively resistant to teratogen-induced cell death. An example of the latter selectivity is seen in the cells of the developing heart, which are resistant to the cytotoxic potential of many teratogens. We show that the absence of cell death in the heart is accompanied by the complete lack of DNA fragmentation, activtion of caspase-3 and the cleavage of PARP.",
Arsenic,2252589,"Irradiation by gallium-aluminum-arsenate (GaAlAs) diode laser enhances the induction of nitric oxide by porphyromonas gingivalis in RAW 264.7 cells Abstract: Background: Low-level laser irradiation promotes cell viability and wound healing in periodontal tissue. However, its effect on periodontal pathogenic bacteria is unknown. The purpose of this study was to investigate the biological effect of low-level laser irradiation on Porphyromonas gingivalis. Methods: A murine macrophage cell line (RAW 264.7), was cultured and treated with gallium-aluminum-arsenate (GaAlAs) laser-irradiated P. gingivalis with varying levels of energy fluency. Gene expression of monocyte chemotactic protein (MCP)-1, interleukin (IL)-6, Interferon (IFN)-? and inducible nitric oxide synthase (iNOS) was examined by reverse transcription-polymerase chain reaction. Production of iNOS was determined by Western blot analysis and nitric oxide (NO) release was assessed using Griess reagent. Flow cytometric analysis was performed to determine the activation of Toll-like receptors (TLR) in response to P. gingivalis. Results: The laser-irradiated P. gingivalis significantly enhanced mRNA and protein levels of iNOS in RAW 264.7. Although the laser irradiation on P. gingivalis did not alter the expression level of MCP-1, IL-6 and IFN-?, it showed a noticeable effect on NO production in RAW 264.7. Furthermore, the laser-irradiated P. gingivalis accelerated TLR2 activation, but not TLR4 activation. Conclusions: This study revealed that GaAlAs laser irradiation on P. gingivalis induced iNOS expression at transcriptional and translation level and increased NO release in macrophages. Moreover, we confirmed that this process was mediated specifically by TLR2 activation. These findings suggest that low-level laser irradiation to periodontal pathogenic bacteria could be detrimental to periodontal treatments.",
Arsenic,1521791,"Speciation of heavy metals in the sediments of former tin mining catchment Abstract: The chemical speciation of heavy metals (arsenic, chromium, copper, lead, zinc and tin) in the sediments of former tin mining catchment Bestari Jaya, Peninsular Malaysia was determined by using the latest version of the Community Bureau of Reference, usually called the BCR 3-step sequential extraction procedure. Furthermore, a fourth step was introduced for digestion and analysis of the residue. The analysis of total metal content was carried out by using microwave acid digestion. The percentage of each metal obtained from the 4 step extraction (acid-soluble + reducible + oxidizable + residual) is in good agreement with the percentage of total metal content obtained from microwave digestion, which implies the accuracy of the procedure. The degree of pollution in catchment sediments was assessed using geoaccumulation index I-geo and pollution intensity I-POLL. The results indicate that (1) the sediments have been polluted with arsenic (8.8%), chromium (12.9%), copper (17.4%), lead (19.5%), zinc (14.9%) and tin (33.8%) and have high anthropogenic influences; (2) the calculation of geoaccumulation index suggests that catchment sediments have the background concentration for all studied metals (I-geo &lt; 0); (3) High I-POLL showed that all of these heavy metals pose high environmental risk. (4) the mobility order of metals in sediments at SI and S2 was Sn&gt;Pb&gt;Zn&gt;Cr &gt;Cu &gt;As, whereas at S3, S4 and S5, Cu&gt;Pb&gt;Zn&gt;Cr&gt;Sn&gt;As; In conclusion, acidic pH, total organic carbon, scavenging ability and co-precipitation (inclusion, occlusion and adsorption) of studied metals with non-metals could account for change in the geo-chemistry of the catchment sediments.",
Arsenic,1508604,"Preparation and sorption studies of glutaraldehyde cross-linked chitosan copolymers Abstract: Chitosan-glutaraldehyde copolymer sorbents were synthesized by reacting variable weight ratios (low, medium, and high) of glutaraldehyde with fixed amounts of chitosan. Two commercially available chitosan polymers with low (L) and high (H) relative molecular weights were investigated. The chitosan-glutaraldehyde (Chi-Glu) copolymer sorbents are denoted as CPL-X or CPH-X where X denotes the incremental level (X=-1, -2, -3) of glutaraldehyde. The copolymers were characterized using FT-IR spectroscopy and TGA. The solid-solution sorption isotherms in alkaline aqueous solution for the copolymers were characterized using absorbance and emission based spectroscopic methods for p-nitrophenol (PNP) and the arsenate oxoanion HAsO species, respectively. The Sips isotherm model was utilized to obtain sorption parameters at pH 8.5 and 295K (i.e. sorbent surface area, sorption capacity and removal efficiency) for each copolymer sorbent. The sorbent surface areas for the low molecular weight chitosan copolymers are listed in parentheses (mg), as follows: CPL-1 (124), CPL-2 (46.7) and CPL-3 (31.6). The high molecular weight chitosan copolymers are as follows: CPH-1 (79.8), CPH-2 (64.7) and CPH-3 (96.3). The removal efficiencies depend on the pH, temperature, and the relative amounts of sorbate and sorbent. The sorbent removal efficiencies for p-nitrophenol ranged between 7.1% and 49%, and the values for HAsO ranged between 31% to 93% for the low and high molecular weight copolymers.",
Arsenic,1360163,"Nonspecific interstitial pulmonary fibrosis: Association with asbestos fibers detected by electron microscopy Abstract: HEEP COPYRIGHT: BIOL ABS. Lung tissue that showed severe interstitial fibrosis with no evidence of mineral particles on light microscopy was examined in the electron microscope. Although the patient had no exposure to known pathogenic dusts, electron microscopy demonstrated ubiquitous fibrils of chrysotile asbestos, averaging 27.5 nm in width and less than 100 nm in length-well below the resolution of a light optical system. Lung tissue showing alterations diagnosed as ""usual interstitial pneumonia,"" ""fibrosing alveolitis"" or ""idiopathic pulmonary dibrosis"" should be examined by electron microscopy to determine if it really is a pneumoconiosis with evidence of mineral dusts.",
Arsenic,2337099,"Efficient Removal of Arsenic Using Magnetic Multi-Granule Nanoclusters Abstract: Magnetic multi-granule nanoclusters (MGNCs) were investigated as an inexpensive means to effectively remove arsenic from aqueous environment, particularly groundwater sources consumed by humans. Various size MGNCs were examined to determine both their capacity and efficiency for arsenic adsorption for different initial arsenic concentrations. The MGNCs showed highly efficient arsenic adsorption characteristics, thereby meeting the allowable safety limit of 10 mu g/L (ppb), prescribed by the World Health Organization (WHO), and confirming that 0.4 g and 0.6 g of MGNCs were sufficient to remove 0.5 mg/L and 1.0 mg/L of arsenate (AsO43-) from water, respectively. Adsorption isotherm models for the MGNCs were used to estimate the adsorption parameters. They showed similar parameters for both the Langmuir and Sips models, confirming that the adsorption process in this work was active at a region of low arsenic concentration. The actual efficiency of arsenate removal was then tested against 1 L of artificial arsenic-contaminated groundwater with an arsenic concentration of 0.6 mg/L in the presence of competing ions. In this case, only 1.0 g of 100 nm MGNCs was sufficient to reduce the arsenic concentrations to below the WHO permissible safety limit for drinking water, without adjusting the pH or temperature, which is highly advantageous for practical field applications.",
Arsenic,737304,"Dose-response relationship between prevalence of cerebrovascular disease and ingested inorganic arsenic Abstract: Circulatory diseases such as ischemic heart disease and peripheral vascular disease induced by long-term arsenic exposure have been well documented in previous studies, but the dose-response relationship between cerebrovascular disease and ingested inorganic arsenic remains to be elucidated. The prevalence of cerebrovascular disease among residents of the Lanyang Basin on the northeast coast of Taiwan was surveyed to examine its association with exposure to arsenic in well water.<br /><br /> A total of 8102 men and women from 3901 households were recruited in this study. The status of cerebrovascular disease of study subjects was identified through home-visit personal interviews and ascertained by review of hospital medical records according to the World Health Organization criteria. Information on consumption of well water, sociodemographic characteristics, cigarette smoking, and alcohol consumption habits, as well as personal and family history of diseases, was also obtained. Arsenic concentration in the well water of each household was determined by hydride generation and atomic absorption spectrometry. Logistic regression analysis was used to estimate multivariate-adjusted odds ratios and 95% confidence intervals for various risk factors of cerebrovascular disease.<br /><br /> A significant dose-response relationship was observed between arsenic concentration in well water and prevalence of cerebrovascular disease after adjustment for age, sex, hypertension, diabetes mellitus, cigarette smoking, and alcohol consumption. The biological gradient was even more prominent for cerebral infarction, showing multivariate-adjusted odds ratios of 1.0, 3.4, 4.5, and 6.9, respectively, for those who consumed well water with an arsenic content of 0, 0.1 to 50.0, 50.1 to 299.9, and > 300 micrograms/L.<br /><br /> Long-term exposure to inorganic arsenic from well water was associated with an increased prevalence of cerebrovascular disease, especially cerebral infarction.",
Arsenic,1348515,"Effect of the activated Raf protein kinase on the human multidrug resistance 1 (MDR1) gene promoter Abstract: Revealing the regulatory mechanism of the multidrug resistance 1 (MDR1) gene is important to gain understanding of MDR in tumor cells. Using MDR1 deletion constructs and the 22W mutant of c-Raf in which the NH2-terminal half has been deleted, we examined the effect of the activated Raf on human MDR1 promoter activity in transient expression assay and stable transfectants of GHE-L cells. A DNA sequence exhibiting strong activation of MDR1 promoter by 22W was located between -197 and -136 containing the upstream heat shock element (HSE) motifs without other regulatory elements, whereas the MDR1 deletion construct containing downstream HSE motif showed a relatively weaker activation by 22W. We observed that the activated Raf significantly potentiated the induction of MDRCAT activity in GHE-L cells by sodium arsenite or heat shock, which stimulates heat shock factor (HSF) binding to HSE. In addition, protein kinase A inhibitor (H-87) blocked the activation of the MDR1 promoter by 22W in GHE-L cells in a dose-dependent manner. From these results, we propose the possibility that Raf- and protein kinase A-dependent pathways control the transcription of MDR1 gene via a mechanism involving the modulation of HSF activity.",
Arsenic,2025371,"Does nitric oxide activate antioxidant enzymes in plants exposed to arsenic? Abstract: Nitric oxide (NO) is an important cell signaling agent in responses to various kinds of abiotic stress conditions. Under oxidative stress plants produce toxic levels of oxygen reactive intermediates (ROIs), causing damage to cell metabolism. Experimental data is suggestive of an antioxidant action of the NO in plants subjected to abiotic stresses, such as exposed to toxic levels of arsenic (As). The objective of this research was to evaluate the effect of NO, exogenously supplied, on the activity of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) in water hyacinth (Eichhornia crassipes) exposed to toxic levels of As. Plants grown in nutrient solution were exposed to the following treatments: T0 (control), T1 (20 mu M As), T2 (20 mu M As + 100 mu M SNP) and T3 (100 mu M SNP). The SNP (sodium nitroprusside) was the exogenous supplement of NO. After 0, 4, 12 and 24 hr root samples were taken and the antioxidant enzymes activities were determined. The activities of the antioxidant enzymes increased in the plant exposed to toxic levels of As (T1) and with time. Addition of SNP (T2) to the nutrient solution, however, did not increase the activities of the enzymes as expected, probably as a result of a reduction in ROIs content, substrate of the antioxidant enzymes. Probably, NO may be directly used as antioxidant agent reducing the availability of substrates to the enzymes, and therefore reducing cell damage.",
Arsenic,1341235,"Phosphorylation of the M3/6 dual-specificity phosphatase enhances the activation of JNK by arsenite Abstract: Specific outcomes upon activation of the c-Jun N-terminal kinase (JNK) pathway critically depend on the intensity and duration of signal transmission. Dual-specificity phosphatases (DUSPs) play a very important role in these events by modulating the extent of JNK phosphorylation and activation and thus regulating cellular responses to stress. M3/6 (DUSP8) is one of the dual-specificity protein phosphatases with distinct specificity towards JNK. It has been shown that M3/6 itself is phosphorylated by JNK upon stimulation with arsenite, but the role of this phosphorylation has not been investigated. In this study, we mapped JNK-induced phosphorylation sites on M3/6 using mass spectrometry. Phosphorylated residues Ser 515, Thr 518 and Ser 520 were identified and site-directed mutagenesis was employed to investigate their role. Upon arsenite stimulation, M3/6 mutated at these sites exhibited decreased phosphorylation compared to the wild-type protein. No difference was observed in terms of the enzyme's in vitro phosphatase activity, its substrate specificity towards JNK isoforms, its interactions with JNK and the scaffold family of JNK-interacting proteins (JIPs), its stability or its subcellular localization. Interestingly, expression of M3/6 phosphorylation mutants delayed the time-course of JNK phosphorylation and activation by arsenite. We propose that phosphorylation of the M3/6 phosphatase by JNK in response to stress stimuli results in attenuation of phosphatase activity and acceleration of JNK activation.",
Arsenic,627224,"Cytogenetic damage and genetic variants in the individuals susceptible to arsenic-induced cancer through drinking water Abstract: In West Bengal, India, more than 300,000 arsenic-exposed people are showing symptoms of arsenic toxicity, which include cancers of skin and different internal organs. Since only 15-20% of the exposed population manifest arsenic-induced skin lesions, it is thought that genetic variation might play an important role in arsenic toxicity and carcinogenicity. A total of 422 unrelated arsenic-exposed subjects (244 skin-symptomatic and 178 asymptomatic) were recruited for this study. Cytogenetic damage, as measured by chromosomal aberrations in lymphocytes and micronuclei formation in oral mucosa cells, urothelial cells and binucleated lymphocytes, was studied in unexposed, skin-symptomatic and asymptomatic individuals with similar socioeconomic status. Identification of null mutations in GSTT1 and GSTM1 genes were carried out by PCR amplification. GSTP1 SNPs, implicated in susceptibility to various cancers, were assessed by PCR-RFLP method. Symptomatic individuals had higher level of cytogenetic damage compared to asymptomatic individuals and asymptomatic individuals had significantly higher genotoxicity than unexposed individuals. No difference in allelic variants in GSTT1 and GSTP1 was observed between these 2 groups. Incidence of GSTM1 null gene frequencies was significantly higher in the asymptomatic group. Individuals with GSTM1-positive (at least one allele) had significantly higher risk of arsenic-induced skin lesions (odds ratio, 1.73; 95% confidence interval, 1.24-2.22). These results show a protective role of GSTM1 null in arsenic toxicity. This study also indicates that asymptomatic individuals are sub clinically affected and are also significantly susceptible to arsenic-induced genotoxicity.",
Arsenic,2337253,"Arsenic concentrations in paddy soil and rice and health implications for major rice-growing regions of cambodia Abstract: Despite the global importance of As in rice, research has primarily focused on Bangladesh, India, China, and the United States with limited attention given to other countries. Owing to both indigenous As within the soil and the possible increases arising from the onset of irrigation with groundwater, an assessment of As in rice within Cambodia is needed, which offers a &quot;base-case&quot; comparison against sediments of similar origin that comprise rice paddy soils where As-contaminated water is used for irrigation (e.g., Bangladesh). Here, we evaluated the As content of rice from five provinces (Kandal, Prey Veng, Battambang, Banteay Meanchey, and Kampong Thom) in the rice-growing regions of Cambodia and coupled that data to soil-chemical factors based on extractions of paddy soil collected and processed under anoxic conditions. At total soil As concentrations ranging 0.8 to 18 ?g g(-1), total grain As concentrations averaged 0.2 ?g g(-1) and ranged from 0.1 to 0.37 with Banteay Meanchey rice having significantly higher values than Prey Veng rice. Overall, soil-extractable concentrations of As, Fe, P, and Si and total As were poor predictors of grain As concentrations. While biogeochemical factors leading to reduction of As(V)-bearing Fe(III) oxides are likely most important for predicting plant-available As, husk and straw As concentrations were the most significant predictors of grain-As levels among our measured parameters.",
Arsenic,1337717,"Effect of vitamin E supplementation on mRNA expression of superoxide dismutase and interleukin-2 in arsenic exposed goat leukocytes Abstract: The aim of this study was to quantify the expression level of genes involved in antioxidant defenses during inorganic arsenic (iAs) exposure in the blood of goats and to evaluate the regulative activity on these genes of antioxidant vitamin E in the diet. Twenty-four crossbred lactating goats (Alpine × Beetal) were distributed randomly into four equal groups (Control, T(1), T(2) and T(3)) of six in each, on the basis of average body weight (36.10 ± 0.11 kg) and milk yield (1.61 ± 0.004 kg/day). The animals in T(1), T(2) and T(3) were given 50 mg/kg dry matter arsenic daily, while in T(2) and T(3), vitamin E @100 IU and 150 IU/kg dry matter, respectively, was also supplemented additionally for the period of 12 months. Blood was sampled at 0 day then at 3 months interval and analyzed for the expression level of superoxide dismutase (Cu/Zn SOD) and interleukin-2 (IL-2) using real-time PCR technique. Initially there was no difference (p &gt; 0.05) in relative expression of the two genes. But, at 3 months, relative expression of Cu/Zn SOD increased (p &lt; 0.05) in T(1) groups then, at 6 and 9 months expression was decreased (p &lt; 0.05) in all the iAs treated groups whereas at 12 months, vitamin E supplementation increased (p &lt; 0.05) the expression which is comparable to control groups. IL-2 mRNA expression was decreased (p &lt; 0.05) at 6 months in all iAs treated groups, at 9 months there was decline trend but not significantly different whereas at 12 months decline trend was less (p &lt; 0.05) in vitamin E supplemented groups. The result suggests that vitamin E may have a controlling effect on oxidative stress through modulation of SOD and IL-2 expression.",
Arsenic,1356025,"Risk factors for asthma admissions in children Abstract: Bronchial asthma is related to a high morbidity rate, leading to an increasing frequency of emergency room visits and hospital admissions. The aim of this study was to identify severity risk factors for childhood asthma related to hospitalization. The authors studied 124 children admitted to the hospital for asthma, during a 2-year period, correlating the obtained data with a sample of outpatients with asthma matched by age, gender, and socioeconomic status. A standardized questionnaire and skin-prick tests (SPTs) were performed on all children. The significant and independent risk factors identified for hospital admission were prior asthma hospitalization (OR = 7.63; 95% CI = 1.5-39.6; p = 0.01) and last-year admission (OR = 3.18; 95% CI = 1.1-8.9; p = 0.02), environmental tobacco-smoke exposure (OR = 6.63; 95% CI = 2.5-17.8; p = 0.002), allergen sensitization (OR = 3.86; 95% CI = 1.4-10.7; p = 0.009), family history of maternal asthma (OR = 3.58; 95% CI = 1.3-9.6; p = 0.01), and onset of symptoms before 12 months of age (OR = 2.76; 95% CI = 1.0-7.9; p = 0.06). Attendance at day care or kindergarten (OR = 0.38; 95% CI = 0.2-0.9; p = 0.04) and large family size (OR = 0.25; 95% CI = 0.1-0.8; p = 0.01) could be protective factors. Our results stress the importance of early diagnosis and specialized medical care of childhood asthma, mainly in high-risk children, with emphasis on medication planning and the establishment of preventive measures such as environmental tobacco smoke avoidance and limitation of aeroallergen exposure.",
Arsenic,1021826,"Up-regulation of cyclin D1 by JNK1/c-Jun is involved in tumorigenesis of human embryo lung fibroblast cells induced by a low concentration of arsenite Abstract: Inorganic arsenic, a ubiquitous environmental contaminant, is associated with an increased risk of cancer. There are several hypotheses regarding arsenic-induced carcinogenesis. The mechanism of action remains obscure, although hyper-proliferation of cells is involved. In the present study, the molecular mechanisms underlying the proliferation and malignant transformation of human embryo lung fibroblast (HELF) cells induced by a low concentration of arsenite were investigated. The results reveal that a low concentration of arsenite induces cell proliferation and promotes cell cycle transition from the G(1) to the S phase. Moreover, arsenite activates the JNK1/c-Jun signal pathway, but not JNK2, which up-regulates the expression of cyclin D1/CDK4 and phosphorylates the retinoblastoma (Rb) protein. Blocking of the JNK1/c-Jun signal pathway suppresses the increases of cyclin D1 expression and Rb phosphorylation, which attenuates cell proliferation, reduces the transition from the G1 to the S phase, and thereby inhibits the neoplastic transformation of HELF cells induced by a low concentration of arsenite. Thus, activation of the JNK1/c-Jun pathway up-regulates the expression of cyclin D1, which is involved in the tumorigenesis caused by a low concentration of arsenite.",
Arsenic,66687,"Health response by questionnaire in arsenic-exposed populations Abstract: The health status of populations exposed to arsenic through drinking water was determined by a mailed questionnaire. Participants were selected from three communities located in Nevada with 1977 tap water arsenic levels of approximately 0.1 mg/l and one California community with 1977 levels around 0.39 mg/l. The questionnaire responses were obtained in 1979 from the four exposed communities and compared to those of a Wyoming community whose tap water levels of arsenic were less than 0.001 mg/l in 1979. No difference in health status for gastrointestinal, neurological, musculoskeletal, circulatory and skin disorders was found. The average number of years of consumption given by length of residence was 6-16 years. We conclude that the health status of these arsenic-exposed populations has not been adversely affected.",
Arsenic,1027813,"Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes in vitro Abstract: Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes were biphasic: The chemicals at very low concentrations enhanced DNA synthesis, whereas higher concentrations inhibited DNA synthesis. The concentrations of arsenicals at which the maximum stimulating effect was found were 1 x 10(-5) M, 1 x 10(-6) or 2 x 10(-6) M, and 0.8 x 10(-6) or 1 x 10(-6) M for sodium arsenite exposure of 1 h, 3 d, and 6 d, respectively; for sodium arsenate, 1 x 10(-5) M, 1 x 10(-5) M, and 2 x 10(-6) or 5 x 10(-6) M, respectively. Arsenicals must be present for the entire 6-d culture period to produce maximum stimulation of DNA synthesis in human lymphocytes. The longer exposure of the lymphocytes to arsenicals, the lower the concentrations of arsenicals at which the maximum stimulating effect on DNA synthesis was found. Stimulating effect of trivalent arsenic (sodium arsenite) on DNA synthesis was stronger than pentavalent arsenic (sodium arsenate), and the stronger the effect of trivalent arsenic than pentavalent, the longer exposure of the cells to the chemicals. Both sodium arsenite and sodium arsenate stimulated DNA synthesis in human lymphocytes to a lower degree than phytohemagglutinin (PHA).",
Arsenic,737128,"The spatial pattern of risk from arsenic poisoning: A Bangladesh case study Abstract: Arsenic poisoning in Bangladesh has been one of the biggest environmental health and social disasters of recent times. About seventy million people in Bangladesh are exposed to toxic levels of arsenic (0.05 mg/L) in drinking water. It is ironic that so many tubewells have been installed in recent times to provide drinking water that is safe from water-borne diseases but that the water pumped is contaminated with toxic levels of arsenic. Along with the clinical manifestations, some social problems have also emerged due to arsenic toxicity. Analysing the spatial risk pattern of arsenic in groundwater is the main objective of this paper. Establishing the extent of arsenic exposure to the people will facilitate an understanding of the health effects and estimating the population risk over the area. This paper seeks to explore the spatial pattern of arsenic concentrations in groundwater for analyzing and mapping 'problem regions' or 'risk zones' for composite arsenic hazard information by using GIS-based data processing and spatial analysis along with state-of-the-art decision-making techniques. Quantitative data along with spatial information were employed and analyzed for this paper.",
Arsenic,1019216,"Dietary protection by iron against clastogenic effects of short-term exposure to arsenic in mice in vivo Abstract: Iron, as freshly prepared aqueous solution of ferrous sulfate, was administered by gavage to laboratory bred Swiss albino mice. The concentration used was 152 mg/kg body weight (1/10 of the LD(50)). While screening for protection against arsenic, in one set of experiment exposure to iron was followed after 2 hr by gavaging with 2.5 mg/kg body weight (1/10 of the LD(50)) of arsenic as sodium (III) meta arsenite in distilled water. In another set, equal amounts (1:1) of ferrous sulfate and sodium arsenite were administered simultaneously. Control sets were given sodium m-arsenite alone and distilled water (vehicle). After exposure for 24 hr in all experiments, mice were sacrificed and chromosome preparations were made from bone marrow according to a colchicine-hypotonic-fixation-air-drying-Giemsa schedule. Cytogenetic endpoints screened were chromosome aberrations and divisional frequencies. Sodium arsenite alone was highly clastogenic. Ferrous sulfate, whether given together with or before exposure to sodium arsenite, reduced the clastogenic effects of the latter to a significant extent.",
Arsenic,2149152,"An Approach to Mixed Pn Asm Ligand Complexes Abstract: The reaction of a P4 butterfly complex with yellow arsenic yields the largest mixed Pn Asm ligand complexes synthesized to date. [{Cp'''Fe(CO)2 }2 (?,?(1:1) -P4 )] reacts with As4 to yield [{Cp'''Fe}2 (?,?(4:4) -Pn As4-n )] and [Cp'''Fe(?(5) -Pn As5-n )]. Mass spectrometry together with NMR spectroscopy and X-ray crystallography give clear evidence about the arrangement of the E positions within the cyclo-E5 and E4 moieties of the products. Moreover, the results of DFT calculations agree well with the experimental determined outcomes. By coordinating the E4 complex [{Cp'''Fe}2 (?,?(4:4) -Pn As4-n )] with CuCl, a rearrangement of the E positions occurs in favor with a preferred phosphorus coordination towards copper atoms in the resulting 1D polymeric chain.",
Arsenic,379745,"Protective role of tannin-rich fraction of Camellia sinensis in tissue arsenic burden in Sprague Dawley rats Abstract: The protective effect of green tea (Camellia sinensis) was tested against arsenic-induced toxicity. However, the possible role of tannins in green tea in alleviating hepatic and renal oxidative injury has also been studied. Administration of sodium arsenite (100 mg/kg/day) for 28 days in Sprague Dawley female rats resulted in significant reduction of biochemical parameters such as delta-aminolevulinic acid dehydratase (ALAD), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and elevation of thiobarbituric acid reactive substances (TBARS) and the index of nitrite/nitrate (NOx) levels. The tissue arsenic burden was increased after arsenic exposure for a period of 28 days. Green tea crude fraction (GTC) co-treated with sodium arsenite for 28 days caused significant (p < .01) elevation of ALAD, GSH, GPx, SOD, and nitrate/nitrite levels and reduction of the TBARS level and tissue burden when compared to detannified green tea fraction (GTDT)-treated groups. The protective role of tannin-rich fraction of C. sinensis when compared to the detannified fraction was also confirmed by histological examinations. The greater activity of GTC than that of detannified green tea fraction correlates with the higher content of tannins in green tea. Overall, these results indicate that the tannin-rich green tea could have improved the defense mechanism against arsenic-induced oxidative stress and reduced the tissue arsenic burden.",
Arsenic,2088325,Evaluation of bioaccessible arsenic in fly ash by an in vitro method and influence of particle-size fraction on arsenic distribution Abstract: ,
Arsenic,1252718,"Development of bacteria-based bioassays for arsenic detection in natural waters Abstract: Arsenic contamination of natural waters is a worldwide concern, as the drinking water supplies for large populations can have high concentrations of arsenic. Traditional techniques to detect arsenic in natural water samples can be costly and time-consuming; therefore, robust and inexpensive methods to detect arsenic in water are highly desirable. Additionally, methods for detecting arsenic in the field have been greatly sought after. This article focuses on the use of bacteria-based assays as an emerging method that is both robust and inexpensive for the detection of arsenic in groundwater both in the field and in the laboratory. The arsenic detection elements in bacteria-based bioassays are biosensor-reporter strains; genetically modified strains of, e.g., Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Rhodopseudomonas palustris. In response to the presence of arsenic, such bacteria produce a reporter protein, the amount or activity of which is measured in the bioassay. Some of these bacterial biosensor-reporters have been successfully utilized for comparative in-field analyses through the use of simple solution-based assays, but future methods may concentrate on miniaturization using fiberoptics or microfluidics platforms. Additionally, there are other potential emerging bioassays for the detection of arsenic in natural waters including nematodes and clams.",
Arsenic,1344874,"Oxidation of a critical thiol residue of the adenine nucleotide translocator enforces Bcl-2-independent permeability transition pore opening and apoptosis Abstract: Mitochondrial membrane permeabilization is a critical event in the process leading to physiological or chemotherapy-induced apoptosis. This permeabilization event is at least in part under the control of the permeability transition pore complex (PTPC), which interacts with oncoproteins from the Bcl-2 family as well as with tumor suppressor proteins from the Bax family, which inhibit or facilitate membrane permeabilization, respectively. Here we show that thiol crosslinking agents including diazenedicarboxylic acid bis 5N, N-dimethylamide (diamide), dithiodipyridine (DTDP), or bis-maleimido-hexane (BMH) can act on the adenine nucleotide translocator (ANT), one of the proteins within the PTPC. ANT alone reconstituted into artificial lipid bilayers suffices to confer a membrane permeabilization response to thiol crosslinking agents. Diamide, DTDP, and BMH but not tert-butylhydroperoxide or arsenite cause the oxidation of a critical cysteine residue (Cys 56) of ANT. Thiol modification within ANT is observed in intact cells, isolated mitochondria, and purified ANT. Recombinant Bcl-2 fails to prevent thiol modification of ANT. Concomitantly, a series of different thiol crosslinking agents (diamide, DTDP, and BMH, phenylarsine oxide) but not tert-butylhydroperoxide or arsenite induce mitochondrial membrane permeabilization and cell death irrespective of the expression level of Bcl-2. These data indicate that thiol crosslinkers cause a covalent modification of ANT which, beyond any control by Bcl-2, leads to mitochondrial membrane permeabilization and cell death.",
Arsenic,1003606,"Proteomic analysis of arsenite - mediated multiple antibiotic resistance in Yersinia enterocolitica biovar 1A Abstract: Arsenic is one of the most important global environmental pollutants. In the present study, fifty one clinical strains of Yersinia enterocolitica biovar 1A showed high resistance to arsenite and arsenate. The minimum inhibitory concentration (MIC) of arsenite (0.625-20 mM) was lower than arsenate (10-80 mM). Growth of Y. enterocolitica in 2 mM arsenite led to 2-8 fold increase in MICs of the five antibiotics (amikacin, ciprofloxacin, gentamycin, kanamycin and tetracycline), suggesting expression of arsenite-induced multiple antibiotic resistance among the strains. Proteomic analysis of Y. enterocolitica revealed differential expression of certain proteins following arsenite exposure, which included a putative outer membrane porin (OmpA) and a putative amino acid transporter protein. In conclusion, modulation of membrane permeability may be involved in the induction of arsenite-mediated expression of multiple antibiotic resistance in Y. enterocolitica. (© 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim).",
Arsenic,496531,"Effects of arsenic exposure from drinking water on spatial memory, ultra-structures and NMDAR gene expression of hippocampus in rats Abstract: Epidemiological investigations indicate that chronic arsenic exposure call damage neurobehavioral function in children. The present study was aimed to study the effects of arsenic exposure from drinking water on the spatial memory, and hippocampal ultra-structures and N-methyl-D-aspartate receptor (NMDAR) gene expression in rats. Sprague-Dawley rats were assigned to four groups: rats in control group drank regular water, rats in other groups drank water with final arsenic concentration of 2.72 mg/L (group A), 13.6 mg/L. (group B) and 68 mg/L(group C), respectively, for 3 months. The levels of arsenic in blood serum and hippocampus were monitored. Rats were tested in Morris water maze (MWM) for memory Status. Samples of hippocampus Were collected from two rats in each group for transmission electron microscopic study and the detection of NMDAR expression by RT-PCR. The rats in group C showed a significant delay in hidden platform acquisition. Neurons and endothelial cells presented pathological changes and the expression of NR2A was down-regulated in hippocampus in arsenic exposed rats. Our data indicated that arsenic exposure of 68 mg/L Caused spatial memory damage, of which the morphological and biochemical bases could be the ultra-structure changes and reduced NR2A expression in hippocampus. (C) 2008 Published by Elsevier Ireland Ltd.",
Arsenic,1070354,"Enrichment of arsenic transforming and resistant heterotrophic bacteria from sediments of two salt lakes in Northern Chile Abstract: Microbial populations are involved in the arsenic biogeochemical cycle in catalyzing arsenic transformations and playing indirect roles. To investigate which ecotypes among the diverse microbial communities could have a role in cycling arsenic in salt lakes in Northern Chile and to obtain clues to facilitate their isolation in pure culture, sediment samples from Salar de Ascotán and Salar de Atacama were cultured in diluted LB medium amended with NaCl and arsenic, at different incubation conditions. The samples and the cultures were analyzed by nucleic acid extraction, fingerprinting analysis, and sequencing. Microbial reduction of As was evidenced in all the enrichments carried out in anaerobiosis. The results revealed that the incubation factors were more important for determining the microbial community structure than arsenic species and concentrations. The predominant microorganisms in enrichments from both sediments belonged to the Firmicutes and Proteobacteria phyla, but most of the bacterial ecotypes were confined to only one system. The occurrence of an active arsenic biogeochemical cycle was suggested in the system with the highest arsenic content that included populations compatible with microorganisms able to transform arsenic for energy conservation, accumulate arsenic, produce H(2), H(2)S and acetic acid (potential sources of electrons for arsenic reduction) and tolerate high arsenic levels.",
Arsenic,1519056,"Private drinking water quality in rural Wisconsin Abstract: Between July 1, 2007, and December 31, 2010, Wisconsin health departments tested nearly 4,000 rural drinking water supplies for coliform bacteria, nitrate, fluoride, and 13 metals as part of a state-funded program that provides assistance to low-income families. The authors' review of laboratory findings found that 47% of these wells had an exceedance of one or more health-based water quality standards. Test results for iron and coliform bacteria exceeded safe limits in 21% and 18% of these wells, respectively. In addition, 10% of the water samples from these wells were high in nitrate and 11% had an elevated result for aluminum, arsenic, lead, manganese, or strontium. The high percentage of unsafe test results emphasizes the importance of water quality monitoring to the health of nearly one million families including 300,000 Wisconsin children whose drinking water comes from a privately owned well.",
Arsenic,1018678,"Geographical and temporal differences in the urinary excretion of inorganic arsenic: a Belgian population study Abstract: <strong>OBJECTIVE: </strong>This Belgian study assessed the geographical and temporal differences in the exposure of the population to inorganic arsenic, a known carcinogen.<br /><br /><strong>METHODS: </strong>In the CadmiBel study (1985-9) the 24 h urinary arsenic excretion was measured, as an index of recent exposure, in industrialised cities (Liège: n = 664, Charleroi: n = 291), in a rural control area (Hechtel-Eksel: n = 397), and in rural districts in which the population had possibly been exposed through the drinking water or the emissions of nonferrous smelters (Wezel: n = 93, Lommel: n = 111, and Pelt: n = 133). In the PheeCad study, in 1991-5, the rural areas (n = 609) were re-examined together with an urban control area (Leuven: n = 152).<br /><br /><strong>RESULTS: </strong>The CadmiBel results showed that after adjustment for sex, age, and body mass index, the 24 h arsenic excretion was on average low in Liège (91 nmol), Charleroi (155 nmol), Hechtel-Eksel (144 nmol), and Wezel (158 nmol), whereas the highest excretions were found in Lommel (570 nmol) and Pelt (373 nmol). During the PheeCad study, the mean 24 h arsenic excretion in the rural areas ranged from 81 to 111 nmol. This was lower than six years earlier and similar to the excretion in the control town (108 nmol). Longitudinal studies in 529 people living in the rural areas confirmed that their 24 h arsenic excretion had decreased (P &lt; 0.001) from 222 to 100 nmol. As well as the drinking water, industry was likely to be a source of the increased exposure in Lommel and Pelt in 1985-9, because at that time the urinary arsenic excretion did not follow the regional differences in the arsenic content of the drinking water, because the fall in the arsenic excretion over time coincided with the implementation by industry of stricter environmental regulations, because in individual subjects the urinary arsenic excretion was inversely correlated with the distance to the nearest smelter, and because an increased arsenic excretion was only found downwind from the main smelter. The official network that monitors the arsenic concentration in airborne and fall out dust did not detect the high exposure in Lommel and Pelt between 1985 and 1989.<br /><br /><strong>CONCLUSION: </strong>This study highlights the necessity to validate environmental monitoring programmes by directly estimating the internal exposure of the population.",
Arsenic,1248945,"Arsenic in drinking water and acute coronary syndrome in Zrenjanin municipality, Serbia Abstract: BACKGROUND: Arsenic is constantly present in drinking water supply systems of Zrenjanin municipality across decades. It presents a great public health problem in Serbia, but its relationship with acute coronary syndrome (ACS) has not been studied previously. OBJECTIVES: The aims of this study were to assess the incidence of ACS in two areas from Zrenjanin municipality consuming different levels of arsenic in drinking water, and to explore the association between arsenic exposure and the probability of fatal outcome of ACS. METHODS: The research was a registry-based ecological study of two populations consuming water with different arsenic levels, based on current guidelines (10?g/L). Median arsenic in the area above national standard was 80?g/L; median arsenic in the other area was 1?g/L. Newly diagnosed cases of ACS were obtained from the National Registry for Acute Coronary Syndrome from 2006 to 2010. RESULTS: The two populations were comparable by age, gender, and prevalence of risk factors for ACS. Standardized incidence rates (SIR) of ACS were higher for people consuming arsenic above standard (average five-year SIR was 237.00 per 100.000; 95% CI=214.93-260.74), in comparison to people consuming arsenic within limits (average SIR=124.40 per 100.000; 95% CI=96.00-158.56). Exposure to arsenic above limits was insignificantly associated with fatal outcome of ACS for the whole population, men and women. CONCLUSIONS: Consumption of arsenic above national standards was associated with higher risk for the occurrence of acute coronary syndrome and with insignificantly higher probability of fatal outcome of ACS in Zrenjanin municipality.",
Arsenic,1070437,"Accumulation kinetics of arsenic in Daphnia magna under different phosphorus and food density regimes Abstract: In the present study, the dissolved uptake, dietary assimilation, and elimination of arsenic (initially added as arsenate) in the freshwater cladoceran Daphnia magna were examined. A biphasic correlation between the arsenic uptake rate and its ambient concentration, as well as a two-saturation-site arsenic uptake competition with phosphate was observed. The calculated uptake rate constant, as influenced by the ambient phosphorus concentration, ranged from 0.035 to 0.35 L/g/d. Food concentration substantially decreased (by 23.2-64.4%) the arsenic assimilation efficiency with the incipient limiting algal food concentration of 3.86?mg/L dry weight. Arsenic assimilation by the daphnids was independent of their own phosphorus status, but was lower when their algal diet was phosphorus-limited and thus contained a higher proportion of arsenite due to the enhanced biotransformation. Arsenic efflux rate constant ranged from 0.34 to 0.44 d(-1) with increased food concentration slightly facilitating its loss. Excretion, accounting for 51.3 to 60.6% of total loss, was the dominant pathway for arsenic elimination with a remarkable contribution from offspring production (24.7-29.8%), whereas molting (3.64-4.05%) and egestion (7.9-11.9%) had minor roles only. According to the well-established biokinetic model, dietary assimilation was predicted to be the main pathway for arsenic bioaccumulation in the daphnids, and arsenic has a great potential to be biodiminished along the food chain. Environ. Toxicol. Chem. © 2012 SETAC.",
Arsenic,1519080,"Arsenic speciation and spatial and interspecies differences of metal concentrations in mollusks and crustaceans from a South China estuary Abstract: Arsenic speciation and concentrations were determined in mollusks and crustaceans in the intertidal zone from twelve locations in Zhanjiang estuary, South China. Metal concentrations (Ag, As, Cd, Cu, Hg, Ni, Pb, and Zn) were also concurrently determined in these species. Arsenic speciation analysis showed that the less-toxic arsenobetaine (AsB) constituted 80.6-98.8 % of all As compounds, and dimethylarsinic acid (DMA) constituted 0.47-3.44 %. Monomethylarsonic acid (MMA) and As(V) were only detected in the whelk Drupa fiscella and the crab Heteropilumnus ciliatus, respectively. Arsenite [As(III)] was not detected in any of the sampled specimens, but there were also unidentified other As species. A strong spatial variation of metals in the oyster Saccostrea cucullata was found in the estuary, confirming that oysters can be used as a good biomonitor of metal contamination in the studied area. The concentrations of eight metals in the studied mollusks and crustaceans clearly revealed that these invertebrates accumulated different metals to different degrees. Furthermore, As, Cd, Cu, Hg, and Pb contents in mollusks and crustacean samples were below the Food and Agricultural Organization (FAO) safe concentrations, thus there was no obvious health risk from the intake of the metals through marine mollusks and crustaceans consumption.",
Arsenic,627015,"Preliminary morphological and histochemical changes in rat spinal cord neurons following arsenic ingestion Abstract: Aqueous sodium arsenite was administered in doses of 1.0, 1.5 and 2.0 mg/kg body weight (bw)/day by intragastric route to adult Wistar rats, (groups II, III and IV, respectively, n = 6 animals/group) for a period of 12 weeks. Controls (group I) received distilled water without added arsenite. At the end of experimental period, four animals from each group were perfusion fixed with 4% paraformaldehyde and two animals from each group were used for fresh tissue purposes (for SDH localization). Fixed tissue blocks from the cervical and lumbar spinal cords were processed for paraffin and cryostat sectioning. Measurements of nuclear area were carried out in cresyl violet (CV) stained paraffin sections by Image Analysis. Cryostat sections (20 ?m) of the cervical and lumbar spinal cords of fixed and fresh frozen tissue blocks (n = 2/group) were stained for localization of cytochrome oxidase (CO) and succinic dehydrogenase (SDH) activities, respectively. Quantitative estimations of enzyme activities was determined from mean grey values obtained by Image Analysis. The results revealed a dose related reduction in the mean log nuclear area and in the two enzyme activities. The differences noted between the cervical and lumbar motor neurons, viz. (i) the decrease in mean log nuclear area were observed only in cervical motor neurons of animals receiving 2.0 mg/kg bw whereas for the lumbar motor neurons this was true of all doses of arsenite; (ii) in general, CO expression was higher in the cervical than in lumbar spinal cord and (iii) reduction in SDH activity was more pronounced in the cervical spinal cord with doses of 1.5 and 2.0 mg/kg bw as compared to lumbar spinal cord. These observations may throw some light on the earlier observations [Jenkins RB. Inorganic arsenic and the nervous system. Brain 1996;89:479–98] reporting differences in the affliction to arsenic ingestion between the fore limb and hind limb musculature (in human subjects). Our observations ascertain that the neurons, which innervate these musculature, also differ in some characteristics.",
Arsenic,1034258,"Induction of 32- and 34-kDa stress proteins by sodium arsenite, heavy metals, and thiol-reactive agents Abstract: Challenge of human or murine melanoma cells with sodium arsenite, heavy metals (Zn2+, Cu2+ and Cd2+), or thiol-reactive agents (p-chloromercuribenzoate and iodoacetamide) induced the synthesis of four stress proteins with molecular masses of 100, 90, 72 (a doublet), and 32 (human) or 34 (murine) kDa. Enhanced expression of the 32- and 34-kDa polypeptides (p32 and p34) preceded or paralleled the synthesis of the other stress proteins. Hyperthermia, the calcium ionophore A23187, and amino acid analogs (L-azetidine-2-carboxylic acid and L-canavanine) induced the formation of the major stress proteins, but failed to increase synthesis of p32 and p34. Characterization of the dose and time dependence of p32 and p34 synthesis in human (A375) and murine (B16-F10) melanoma cells, respectively, indicated that these proteins were subject to similar regulatory mechanisms. Electrophoretic analysis of stressed cells pulsed with different metabolic precursors revealed that p32 and p34 were radiolabeled with [35S]methionine or 3H-amino acids but not by [3H]mannose or [35S]cysteine. Polyclonal antibodies raised against human p32 cross-reacted with murine p34. These data suggest that p32 and p34 are closely regulated human and murine gene products, respectively, whose synthesis can be modulated by thiol-reactive reagents. Induction of p32 and p34 by these agents, but not by heat shock, suggests that these proteins are a subset of stress-inducible gene products.",
Arsenic,1597376,"Examining church capacity to develop and disseminate a religiously appropriate HIV tool kit with African American churches Abstract: Increasingly, African American churches have been called upon to assist in efforts to address HIV/AIDS in underserved communities. African Americans churches may be well-positioned to provide HIV education, screening, and support services, particularly if they are equipped with church-appropriate, easy-to-deliver HIV tools that can be implemented through the naturalistic church environment. To inform the development of a church-based HIV tool kit, we examined church capacity with African American church leaders (N?=?124 participants; n?=?58 churches represented by senior pastors). Nearly all participants (96%) wanted to learn more about HIV and how to discuss it with their parishioners. Regarding church capacity, most of their representative churches held three regular services each week, facilitated various inreach and community outreach ministries, and had paid staff and computers. Also, many of their churches facilitated HIV/AIDS education/prevention and adolescent sex education activities. Guided by church capacity findings, an ecological framework, and a CBPR approach, we describe the resulting church-based HIV Tool Kit that &quot;fits&quot; naturalistically within a multilevel church infrastructure, builds upon churches' HIV-related experience, and equips faith leaders to efficiently promote HIV services with the communities they serve.",
Arsenic,2345715,"Degradation of antibiotic amoxicillin using 1 x 1 molecular sieve-structured manganese oxide Abstract: The kinetics and mechanism of amoxicillin (AMO) degradation using a 1 x 1 molecular sieve-structured manganese oxide (MnO2) was studied. The presence of the buffer solution (i.e., NaHCO3, NaH2PO4 and KH2PO4) diminished AMO binding to MnO2, thus reducing AMO degradation in the pretest; therefore, all other experiments in this study were conducted without the addition of a buffer. Third-order rate constants, second-order on AMO and first-order on MnO2 increased with elevating pH level (2.81-7.23) from 0.54 to 9.17 M-2 s(-1), and it decreased to 4.27 M-2 s(-1) at pH 8.53 beyond the pk(a2) of AMO (7.3). The dissolution of the MnO2 suspension with and without AMO exhibited a similar trend; that is, Mn2+ concentration increased with decreasing pH. However, the dissolution of MnO2 with AMO was greater than that without AMO, except for the reaction occurring at pH 8.53, partially indicating that MnO2 acts as an oxidant in AMO degradation. The preliminary chromatogram data display different products with varying pH reaction s, implying that AMO elimination using this 1 x 1 molecular sieve-structured MnO2 is by adsorption as well as oxidative degradation. A complementary experiment indicates that the amount of oxidatively degraded AMO increases substantially from 65.5% at 4 h to 95% at 48 h, whereas the AMO adsorbed onto MnO2 decreases slightly from 4.5% at 4 h to 2.4% at 48 h. The oxidative degradation accounted for more AMO removal than adsorption over the whole reaction course, indicating that the oxidative reaction of AMO on MnO2 dominated the AMO removal.",
Arsenic,1070389,"Phytoremediation of an arsenic-contaminated site using Pteris vittata L. and Pityrogramma calomelanos var. austroamericana: a long-term study Abstract: This field study investigated the phytoremediation potential of two arsenic (As) hyperaccumulating fern species, Pityrogramma calomelanos var. austroamericana and Pteris vittata over 27-month duration at a disused As-contaminated cattle-dip site located at Wollongbar, NSW, Australia. Ferns planted in January 2009 were harvested following 10, 22 and 27 months of growth. A detailed soil sampling was undertaken in June 2009 (initial, n?=?42 per plot) and limited sampling in April 2011 (after 27 months, n?=?15 per plot) to measure total and phosphate-extractable As concentrations in soil at 0?-?20-, 20?-?40- and 40?-?60-cm depths. The choice of the limited number of samples was considered sufficient to estimate the changes in soil As concentration following phytoremediation based on a geostatistical model. The average frond dry biomass, As concentration and As uptake were significantly (P?&lt;?0.001?-?0.05) greater in P. calomelanos var. austroamericana than P. vittata, at all three harvests (1.6?-?4.3, 1.3?-?1.5 and 2.2?-?5.7 times, respectively). After 27-months of growth, P. calomelanos var. austroamericana removed 8,053 mg As (i.e. cumulative over three harvests) in plot B (25.4 kg As ha(-1)) that was 2.65 times higher than that depleted by P. vittata (3,042 mg As in plot A (9.7 kg As ha(-1))). The cumulative frond As uptake data of the two fern species revealed that P. calomelanos var. austroamericana extracted 1.7?-?3.9 % and P. vittata removed 0.53?-?1.5 % of total As from soil at three depths. However, for the surface (0?-?20 cm) and subsurface (40?-?60 cm) layers, the (post-experiment) soil As data indicated that total As concentration in soil was reduced by 49 and 63 % (P?&lt;?0.05), respectively, using P. calomelanos var. austroamericana; and 17 and 15 % (P?&gt;?0.05), respectively, by P. vittata. Our results show that phytoremediation time based on observed changes in soil As based on limited sampling is not reliable; hence, it is recommended that the frond As uptake should be considered in order to evaluate the phytoremediation efficiency of the two fern species at the experimental site. Using As uptake of the two fern species, we estimate that with P. calomelanos var. austroamericana it would take 55?-?125 years to decrease mean total As content below the ecological investigation level (20 mg kg(-1)) in the surface and subsurface soils, whereas with P. vittata 143?-?412 years would be required to achieve this target.",
Arsenic,1508697,"Mercury, arsenic and selenium concentrations in water and fish from sub-Saharan semi-arid freshwater reservoirs (Burkina Faso) Abstract: Despite intensive mining activities in Burkina Faso, little is known on the environmental impacts of metals and metalloids potentially released from these activities. Water samples and 334 fish from 10 reservoirs were taken in order to evaluate the extent of mercury (Hg), selenium (Se) and arsenic (As) contamination in aquatic systems and their potential health risk for humans and wildlife, taking into account their antagonistic interactions. Water and fish levels of these elements were relatively low and did not reveal an important impact of gold mining activities. Water temperature and conductivity were the key factors associated with higher levels of MeHg. Higher sulfate content was reported in sites with more particulate Hg, As and Se, suggesting anthropogenic origin of metal(loid) inputs in water reservoirs. Metal(loid) concentrations in fish were low and ranged from 0.002 to 0.607?g/g wet weight (w.w.) for Hg, 0.023 to 0.672 for Se and 0.039 to 0.42 for As. These levels are similar or slightly higher than those reported in many other studies from Africa. Nevertheless, more than 70% of piscivore fish exceeded the threshold for wildlife protection for MeHg. Further, a traditional risk analysis performed ignoring Se antagonism indicated that these piscivores should be consumed by humans with caution. However, when taking into account the antagonistic effect of Se on Hg toxicity, up to 99% of all fish could be protected from Hg toxicity by their Se content. When considering both As/Se and Se/Hg antagonism, 83% instead the 99% of fish should be considered safe for consumption. Fish Se and As concentrations did not pose potential risk for both animals and humans. Overall, these reservoirs were relatively unaffected by As, Se and Hg contamination despite the rising gold mining activities. Further, considering antagonistic effects of As, Se and Hg may help refine consumption advisories.",
Arsenic,2278577,"Leachability, bioaccessibility and plant availability of trace elements in contaminated soils treated with industrial by-products and subjected to oxidative/reductive conditions Abstract: Two industrial by products, red mud (RM) and aluminum-rich water treatment residue (Al-WTR) were used (2% w/w) for the immobilization of As, Cu and Pb in two polluted soils. Soil-1 was a mine contaminated soil (2428 As, 234 Cu and 559 Pb mg kg(-1)); Soil-2 was a chromated copper arsenate contaminated soil (860 and 1500 mg kg(-1) of As and Cu respectively). Two different redox conditions (aerobic and 3 repeated reduction/oxidation cycles) were also applied. The immobilization of trace elements and their bioaccessibility were evaluated through a leaching test and simplified bioaccessibility extraction test (SBRC) respectively, whereas phytoavailability was assessed in pot trials with Lolium perenne. <br> <br>The RM addition increased the solubility of As and Pb, under both redox conditions, in Soil-1 with respect to untreated soil (i.e., +40 and 38% respectively in RMsw-Soil-1 in aerobic condition). In Soil-2 Al-WTR was the amendment most efficient at decreasing As mobility (&lt;50% with respect to untreated soil). The high correlations detected between trace element mobility and dissolved organic carbon (DOC) suggests that As, Cu and Pb formed soluble organic complexes. The SBRC results suggested that this test was mainly affected by physical and chemical characteristics of soils, whereas trial pot showed that the treatments with RMsw and Al-WT in aerobic condition were able to decrease the plant uptake of As by 34 and 57% in Soil-1, and by 88 and 87% in Soil-2. These treatments also reduced uptake of Cu from Soil-2 (by 68 and 86%) and of Pb from Soil-1 (by 52 and 34%). <br> <br>The results of this study show that the efficacy of the soil amendments is a complex function of soil conditions, source of contamination, and perhaps most importantly the environmental endpoint considered. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,184387,"Infectious and noninfectious exposures in the etiology of light chain myeloma: A case-control study Abstract: Sixty-nine subjects with light chain myeloma were interviewed in a multicenter case-control study, and their responses were compared to those of 1683 controls selected from the general population of the same geographic areas. The interview was directed at the subject's history of exposure to a variety of chemical and infectious agents. Persons with a history of a medical implant had 2.2 times the risk of other persons (95% confidence interval = 0.9-5.8), a relative risk that increased with increasing time that the implant had been present. Alkali exposure that was deemed by the subject to be unusually heavy was associated with a relative risk of light chain myeloma of 7.8 (95% confidence interval = 1.7-35.3), while similarly defined exposure to carbon monoxide increased the risk by 6.1 times (95% confidence interval = 2.0-18.2). These findings differ from those obtained in our study of the more common forms of multiple myeloma and, while the differences are plausibly due only to chance given the large number of exposures investigated, they could be an indication that light chain myeloma is an etiologically distinct entity.",
Arsenic,49874,"Exposure to environmental tobacco smoke in the household and urinary cotinine excretion, heavy metals retention, and lung function Abstract: The relationship between urinary levels of cotinine (U-cotinine) and arsenic (U-As), blood levels of cadmium (B-Cd), blood levels of lead (B-Pb), lung function, and questionnaire data on smoking habits were studied in 107 parents and their 46 children (7-10 y of age). There was a statistically significant relationship between the reported amount of tobacco smoked and U-cotinine levels. Nonsmokers who were married to persons who smoked had three times higher U-cotinine levels than nonsmokers whose spouses did not smoke. There was a significant association between the number of parents who smoked in the family and the U-cotinine levels of children. If only one parent smoked, maternal smoking was of greater importance than paternal smoking. There was also an association between U-cotinine and B-Cd. A study of lung function in the children revealed that vital capacity and functional residual capacity (corrected for sex, age, and height) increased as the number of parents who smoked increased. Therefore, the present study showed that (1) U-cotinine was a useful index of active smoking and environmental tobacco smoke exposure in adults and children, (2) U-cotinine was associated with the blood concentration of cadmium, and (3) environmental tobacco smoke exposure was associated with changes in lung function of children.",
Arsenic,1027737,"Invisible killers: Heavy metals, saturnine envy, and the tragic death of Raphaelle Peale Abstract: ",
Arsenic,1175748,"Predicting later-life outcomes of early-life exposures Abstract: Background. Exposure of the fetus in utero to a stressor can lead to disease in later life. Epigenetic mechanisms are likely mediators of later life expression of early life events. Objectives. Present the current state of understanding of later life diseases resulting from early life exposures, identify in utero and postnatal indicators of later life diseases, articulate an agenda for future research, and consider the risk assessment implications of this emerging knowledge. Methods. The authors participated in a National Research Council workshop entitled ""Use of In utero and Postnatal Indicators to Predict Health Outcomes Later in Life: State of the Science and Research Recommendations"" and subsequently developed this review. A case study approach highlights the later life consequences of early life malnutrition and arsenic exposure. Discussion. The environmental sensitivity of the epigenome is viewed as an adaptive mechanism by which the developing organism adjusts its metabolic and homeostatic systems to suit the anticipated extrauterine environment. Inappropriate adaptation may produce a mismatch resulting in subsequent increased susceptibility to disease. A nutritional mismatch between the pre- and postnatal environments, or early life obesogen exposure, may explain at least some of the recent rapid increases in the rates of obesity, type II diabetes and cardiovascular diseases. Early life arsenic exposure is also associated with later life diseases, including cardiovascular disease and cancer. Conclusions. With mounting evidence connecting early life exposures and later life disease, new strategies are needed to incorporate this emerging knowledge into health protective practices.",
Arsenic,1025302,"Unventilated indoor coal-fired stoves in Guizhou province, China: Reduction of arsenic exposure through behavior changes resulting from mitigation and health education in populations with arsenicosis Abstract: We report the results of a coordinated mitigation effort aimed at reducing arsenic (As) exposure in three counties of Guizhou province, China. Mitigation occurred in 2005 and encompassed 21 villages with 47,000 inhabitants, who were exposed to high levels of As in their diet through consumption of As-contaminated chili peppers and corn dried over unventilated stoves that burned coal containing high levels of As. The coal was mined by villagers from local pits. Inhalation of air that contained high levels of As contributed to approximately 25% of the daily As intake of 6-9 mg. Before mitigation, a baseline survey of 45,364 residents in 2004 identified more than 2,800 individuals with arsenicosis. The survey also found that many residents were aware of the health effects of As in general but lacked in-depth understanding of the link between coal use and arsenicosis. Consequently, an overwhelming majority (&gt; 95%) continued to use high-As coal. This survey provided the basis for a health education campaign that promoted lifestyle changes coupled with the shutting down of local coal pits and the installation of 10,000 new stoves with chimneys for ventilation. The cost of the mitigation was about 4 million Yuan RMB (US$500,000) and was financed mostly by the government. A postmitigation response survey in 2005 found that &gt; 85% of the residents now associate the use of coal with arsenicosis; &gt; 90% correctly learned to operate the new ventilated stoves; and &gt; 90% dry corn and chili peppers outdoors in the sun. Urinary As concentrations in the region decreased from 0.198 +/- 0.300 mg/L (n = 144) in 2004 to 0.049 +/- 0.009 mg/L (n = 50) in 2005 in individuals with arsenicosis (p &lt; 0.01), which is consistent with the behavior changes.",
Arsenic,1356330,"Arsenic and medical surveillance Abstract: The relative worth of assessing arsenic in blood, urine, hair and nails as a measure of occupational exposure is examined. Blood levels of arsenic decline too rapidly to be useful for monitoring workers. Hair arsenic analysis may be useful on a group basis as screening device for arsenic in the environment; nail analysis has not proven useful for this type of screening. If recent seafood intake is excluded, urine is the most appropriate body fluid for evaluating worker exposure to arsenic. Because epidemiological evidence indicates that arsenic should be treated as a carcinogen; medical surveillance programmes should be developed accordingly.",
Arsenic,1252291,"Effects of monomethylarsonic and monomethylarsonous acid on evoked synaptic potentials in hippocampal slices of adult and young rats Abstract: Arsenite and its metabolites, dimethylarsinic or dimethylarsinous acid, have previously been shown to disturb synaptic transmission in hippocampal slices of rats (Krüger, K., Gruner, J., Madeja, M., Hartmann, L.M., Hirner, A.V., Binding, N., Mubetahoff, U., 2006a. Blockade and enhancement of glutamate receptor responses in Xenopus oocytes by methylated arsenicals. Arch. Toxicol. 80, 492-501, Krüger, K., Straub, H., Binding, N., Mubetahoff, U., 2006b. Effects of arsenite on long-term potentiation in hippocampal slices from adult and young rats. Toxicol. Lett. 165, 167-173, Krüger, K., Repges, H., Hippler, J., Hartmann, L.M., Hirner, A.V., Straub, H., Binding, N., Mubetahoff, U., 2007. Effects of dimethylarsinic and dimethylarsinous acid on evoked synaptic potentials in hippocampal slices of young and adult rats. Toxicol. Appl. Pharmacol. 225, 40-46). The present experiments investigate, whether the important arsenic metabolites monomethylarsonic acid (MMA(V)) and monomethylarsonous acid (MMA(III)) also influence the synaptic functions of the hippocampus. In hippocampal slices of young (14-21 days-old) and adult (2-4 months-old) rats, evoked synaptic field potentials from the Schaffer collateral-CA1 synapse were measured under control conditions and during and after 30 and 60 min of application of the arsenic compounds. MMA(V) had no effect on the synapse functions neither in slices of adult nor in those from young rats. However, MMA(III) strongly influenced the synaptic transmission: it totally depressed the amplitudes of fEPSPs at concentrations of 50 micromol/l (adult rats) and 25 micromol/l (young rats) and LTP amplitudes at concentrations of 25 micromol/l (adult rats) and 10 micromol/l (young rats), respectively. In contrast, application of 1 micromol/l MMA(III) led to an enhancement of the LTP amplitude in young rats, which is interpretable by an enhancing effect on NMDA receptors and a lack of the blocking effect on AMPA receptors at this concentration (Krüger, K., Gruner, J., Madeja, M., Hartmann, L.M., Hirner, A.V., Binding, N., Mubetahoff, U., 2006a. Blockade and enhancement of glutamate receptor responses in Xenopus oocytes by methylated arsenicals. Arch. Toxicol. 80, 492-501). These effects are probably not mediated by changes in cell excitability or in presynaptic glutamate release rates, since antidromically induced population spikes and paired-pulse facilitation failed to show any MMA(III) effect. The impairment of the excitatory CA1 synapse is more likely caused by the action of MMA(III) on postsynaptic glutamatergic receptors and may be jointly responsible for dysfunctions of cognitive effects in arsenic toxicity.",
Arsenic,1016024,"Impairment of mice spermatogenesis by sodium arsenite Abstract: In order to assess the effect of arsenic on the male reproductive impairment in mice, 7-week-old animals were exposed to 7.5 mg sodium arsenite (NaAsO(2))/kg body weight, during 35 days (one spermatogenic cycle). One group of animals was sacrificed after exposure, while another group received distilled water for an additional period of 35 days, in order to study the spermatoxic effect and the recovery of spermatogenesis. In mice sacrificed after NaAsO(2) exposure, a decrease in testis/body weight ratio and reduction of tubular diameter were observed. Both groups of NaAsO(2)-exposed animals showed remarkable histopathological changes, such as sloughing of immature germ cells. Animals sacrificed after NaAsO(2) exposure showed decreased sperm motility, increased abnormal sperm morphology and decreased sperm viability. The effects of NaAsO(2) on sperm motility recovered to normal values after one spermatogenic cycle, while increased sperm abnormality was maintained. However, at this period, a decrease in acrosome integrity was detected. Concerning oxidative stress parameters, animals sacrificed after NaAsO(2) exposure showed a decreased selenium-dependent glutathione peroxidase activity, which was not detected after the recovery. Conversely, at this period, total glutathione peroxidase activity increased in exposed animals. These results demonstrate the toxic effects of NaAsO(2) on mice spermatogenesis and show the lack of recovery after one spermatogenic cycle.",
Arsenic,736934,"Arsenic contamination of groundwater and its health impact on residents in a village in West Bengal, India Abstract: An in-depth study was carried out in Rajapur, an arsenic-affected village in West Bengal, India, to determine the degree of groundwater contamination with arsenic and the impact of this contamination on residents. The flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) method was used to measure arsenic concentrations in water and biological samples. Dermatologists recorded the dermatological features of arsenicosis. Out of a total of 336 hand-pumped tube-wells in Rajapur, 91% (307/336) contained arsenic at concentrations > 10 microg/l, and 63% (213/336) contained arsenic at > 50 microg/l. The type of arsenic in groundwater, the variation in concentrations of arsenic as the depth of tube-wells changed, and the iron concentration in the wells were also measured. Altogether 825 of 3500 residents were examined for skin lesions; of these, 149 had lesions caused by exposure to arsenic. Of the 420 biological samples collected and analysed, 92.6% (389) contained arsenic at concentrations that were above normal. Thus many villagers might be subclinically affected. Although five arsenic-filtering devices had been installed in Rajapur, it appears that villagers are still exposed to raised concentrations of arsenic in their drinking-water. Detailed village-level studies of arsenic-affected areas in West Bengal are required in order to understand the magnitude of contamination and its effects on people. Villagers are ill-informed about the dangers of drinking arsenic-contaminated water. The contamination could be brought under control by increasing community awareness of the dangers and implementing proper watershed management techniques that involve local people.",
Arsenic,628537,"Specificity of arsenite in potentiating cytogenetic damage induced by the DNA crosslinking agent diepoxybutane Abstract: In the present study, the induction of sister chromatid exchanges (SCEs) and chromosomal aberrations were measured in normal human lymphocytes treated with low concentrations of arsenite alone (0.5-2.0 microM) and arsenite in combination with the potent DNA crosslinking agent diepoxybutane (DEB). Experiments were carried out with lymphocytes from blood donors with different sensitivities to SCE induction by DEB. Arsenite, beginning at concentrations as low as 1 microM, increased SCE frequencies; chromosomal aberration frequencies were increased at 2 microM of arsenite. DEB treatments alone increased SCE frequencies and chromosomal aberrations. The yields of chromatid deletions and exchanges in lymphocytes exposed to both arsenite and DEB were markedly increased above the levels expected if the effects of the two agents had been simply additive. The frequencies of chromatid deletions were 4- to 8-fold greater than expected and chromatid exchanges were increased 7- to 40-fold. Chromatid exchanges detected in cells treated with arsenite and DEB were predominately incomplete exchanges. The most dramatic increases in chromatid aberrations were observed in lymphocytes from an individual sensitive to SCE induction by DEB, indicating that individuals may vary in their sensitivity to the co-clastogenic effects of arsenite. At concentrations that dramatically affect aberrations, arsenite had no effect on the induction of SCEs by DEB. These studies suggest a specific interaction of arsenite with the induction or repair of DNA damage produced by DEB that leads to chromosomal aberrations but not to SCEs. Based on the selective chemical reactivity of low concentrations of arsenite with proteins containing vicinal dithiols and the occurrence of these groups within DNA repair proteins, it is proposed that the specific co-clastogenic effects of arsenite may be mediated by its interference with DNA repair activities.",
Arsenic,2298687,"Impact of concomitant surgical atrial fibrillation ablation in patients undergoing aortic valve replacement Abstract: Background:?The clinical benefit of concomitant atrial fibrillation (AF) ablation at the time of aortic valve replacement (AVR) is uncertain. Methods and Results:?A total of 124 patients with AF who underwent AVR with (n=50) or without (n=74) a concomitant maze procedure, between 2000 and 2011, were evaluated. There were no significant differences in early postoperative outcomes. During a median clinical follow-up of 18.1 months (interquartile range: 6.9-47.8 months), 19 late deaths (15.3%) and 33 valve-related complications (26.6%) occurred, but the differences between groups were not statistically significant. Major event-free survival at 5 years was 60.9±9.9% vs. 57.0±10.3% (P=0.41). After adjustment, the maze group demonstrated similar risks for major adverse cardiac events (hazard ratio, 1.18; 95% confidence interval, 0.56-2.49; P=0.67). However, the rate of sinus rhythm restoration at 4 years was significantly higher in the maze group (80.6% vs. 3.6%, P<0.001). Left atrial dimension was smaller (46.9 vs. 50.4mm, P=0.017), and the ejection fraction was higher (60.6% vs. 58.0%, P=0.059) in the maze group. The rate of postoperative anticoagulation was also lower in the maze group (53.1% vs. 89.2%, P<0.001). Conclusions:?Concomitant AF ablation in patients undergoing AVR resulted in increased sinus rhythm restoration, better echocardiographic results, and decreased anticoagulation requirement, without increasing surgical morbidity or mortality.",
Arsenic,1337362,"Assessment of the effluent quality from a gold mining industry in Ghana Abstract: The physical and chemical qualities of the process effluent and the tailings dam wastewater of AngloGold-Ashanti Limited, a gold mining company in Ghana, were studied from June to September, 2010. The process effluent from the gold extraction plant contains high amounts of suspended solids and is therefore highly turbid. Arsenic, copper and cyanide were identified as the major pollutants in the process effluent with average concentrations of 10.0, 3.1 and 21.6 mg?L(-1), respectively. Arsenic, copper, iron and free cyanide (CN(-)) concentrations in the process effluent exceeded the Ghana EPA discharge limits; therefore, it is necessary to treat the process effluent before it can be discharged into the environment. Principal component analysis of the data indicated that the process effluent characteristics were influenced by the gold extraction process as well as the nature of the gold-bearing ore processed. No significant correlation was observed between the wastewater characteristics themselves, except for the dissolved oxygen and the biochemical oxygen demand. The process effluent is fed to the Sansu tailings dam, which removes 99.9 % of the total suspended solids and 99.7 % of the turbidity; but copper, arsenic and cyanide concentrations were still high. The effluent produced can be classified as inorganic with a high load of non-biodegradable compounds. It was noted that, though the Sansu tailings dam stores the polluted effluent from the gold extraction plant, there will still be serious environmental problems in the event of failure of the dam.",
Arsenic,734934,"Effect of folic acid and tetrahydrofolate on tissue arsenic level in rat Abstract: Quest is still going on for a cheap, effective, and easily available remedy for chronic arsenic toxicity. This study was designed to investigate the effects of folic acid and tetrahydrofolate in lowering the arsenic burden in tissues. Rats received arsenic at 700 µg/day by gavage for 28 days except the control group. Arsenic accumulation was significantly lowered (p<0.05), in liver, kidney, heart, lung and skin in both the folic acid and tetrahydrofolate-treated groups compared to arsenic only treated group. The oxidative stress induced by arsenic treatment was reduced as evident by the reduction in rise of malondialdehyde level in both groups. But folic acid was found to be more efficacious compared to tetrahydrofolate.",
Arsenic,628199,"Research toward the development of a biologically based dose response assessment for inorganic arsenic carcinogenicity: A progress report Abstract: Cancer risk assessments for inorganic arsenic have been based on human epidemiological data, assuming a linear dose response below the range of observation of tumors. Part of the reason for the continued use of the linear approach in arsenic risk assessments is the lack of an adequate biologically based dose response (BBDR) model that could provide a quantitative basis for an alternative nonlinear approach. This paper describes elements of an ongoing collaborative research effort between the CIIT Centers for Health Research, the U.S. Environmental Protection Agency, ENVIRON International, and EPRI to develop BBDR modeling approaches that could be used to inform a nonlinear cancer dose response assessment for inorganic arsenic. These efforts are focused on: (1) the refinement of physiologically based pharmacokinetic (PBPK) models of the kinetics of inorganic arsenic and its metabolites in the mouse and human; (2) the investigation of mathematical solutions for multi-stage cancer models involving multiple pathways of cell transformation; (3) the review and evaluation of the literature on the dose response for the genomic effects of arsenic; and (4) the collection of data on the dose response for genomic changes in the urinary bladder (a human target tissue for arsenic carcinogenesis) associated with in vivo drinking water exposures in the mouse as well as in vitro exposures of both mouse and human cells. An approach is proposed for conducting a biologically based margin of exposure risk assessment for inorganic arsenic using the in vitro dose response for the expression of genes associated with the obligatory precursor events for arsenic tumorigenesis.",
Arsenic,627368,"Arsenic exposure in Hungary, Romania and Slovakia Abstract: Inorganic arsenic is a potent human carcinogen and toxicant which people are exposed to mainly via drinking water and food. The objective of the present study was to assess current exposure to arsenic via drinking water in three European countries. For this purpose, 520 individuals from four Hungarian, two Slovakian and two Romanian countries were investigated by measuring inorganic arsenic and methylated arsenic metabolites in urine by high performance liquid chromatography with hydride generation and inductively coupled plasma mass spectrometry. Arsenic in drinking water was determined by atomic absorption spectrometry. Significantly higher concentrations of arsenic were found in both the water and the urine samples from the Hungarian counties (median: 11 and 15 microg dm(-3), respectively; p &lt; 0.001) than from the Slovakian (median: 0.94 and 4.5 microg dm(-3), respectively) and Romanian (median: 0.70 and 2.1 microg dm(-3), respectively) counties. A significant correlation was seen between arsenic in water and arsenic in urine (R(2)= 0.46). At low water arsenic concentrations, the relative amount of dimethylarsinic acid (DMA) in urine was increased, indicating exposure via food. Also, high body mass index was associated with higher concentrations of arsenic in urine (p= 0.03), mostly in the form of DMA. Smokers had significantly higher urinary arsenic concentrations than non-smokers (p= 0.03). In conclusion, elevated arsenic exposure via drinking water was prevalent in some of the counties. Exposure to arsenic from food, mainly as DMA, and cigarette smoke, mainly as inorganic arsenic, are major determinants of arsenic exposure at very low concentrations of arsenic in drinking water.",
Arsenic,1015948,"Metabolites of arsenic and increased DNA damage of p53 gene in arsenic plant workers Abstract: Recent studies have shown that monomethylarsonous acid is more cytotoxic and genotoxic than arsenate and arsenite, which may attribute to the increased levels of reactive oxygen species. In this study, we used hydride generation-atomic absorption spectrometry to determine three arsenic species in urine of workers who had been working in arsenic plants,and calculated primary and secondary methylation indexes. The damages of exon 5, 6, 8 of p53 gene were determined by the method developed by Sikorsky, et al. Results show that the concentrations of each urinary arsenic species,and damage indexes of exon 5 and 8 of p53 gene in the exposed population were significantly higher, but SMI was significantly lower than in the control group. The closely positive correlation between the damage index of exon 5 and PMI,MMA, DMA were found, but there was closely negative correlation between the damage index of exon 5 and SMI. Those findings suggested that DNA damage of exon 5 and 8 of p53 gene existed in the population occupationally exposed to arsenic. For exon 5, the important factors may include the model of arsenic metabolic transformation, the concentrations of MMA and DMA, and the MMA may be of great importance.",
Arsenic,2347669,"Interspecific and locational differences in metal levels in edible fish tissue from Saudi Arabia Abstract: Metal levels in fish have been extensively studied, but little data currently exists for the Middle East. We examined the levels of metals and metalloids (aluminum, arsenic, copper, manganese, selenium, zinc, and mercury) in the flesh of 13 fish species collected from three fishing sites and a local fish market in Jeddah, Saudi Arabia. We tested the following null hypotheses: (1) there are no interspecific differences in metal levels, (2) there are no differences in metal levels in fishes between market and fishing sites, (3) there are no size-related differences in metal levels, and (4) there are no differences in selenium:mercury molar ratio among different fish species. There were significant interspecific differences in concentrations for all metals. There was an order of magnitude difference in the levels of aluminum, arsenic, mercury, manganese, and selenium, indicating wide variation in potential effects on the fish themselves and on their predators. Fishes from Area II, close to a large commercial port, had the highest levels of arsenic, mercury, and selenium, followed by market fishes. Mercury was positively correlated with body size in 6 of the 13 fish species examined. Mercury was correlated positively with arsenic and selenium, but negatively with aluminum, cobalt, copper, manganese, and zinc. Selenium:mercury molar ratios varied significantly among species, with Carangoides bajad, Cephalopholis argus, Variola louti, and Ephinephelus tauvina having ratios below 10:1. These findings can be used in risk assessments, design of mercury reduction plans, development of fish advisories to protect public health, and future management decision-making.",
Arsenic,2064141,Immobilization of trace metals by phosphates in contaminated soil near lead/zinc mine tailings evaluated by sequential extraction and TCLP Abstract: ,
Arsenic,1346560,"Arsenic residues in broiler meat and excreta at arsenic prone areas of Bangladesh Abstract: The aims of this study were to detect arsenic concentrations in feed, drinking water, tissues and excreta of broiler chickens in Bangladesh; and to assess the effect of arsenic in feed and drinking water on the retention of arsenic in broiler tissues and excreta. Total arsenic concentration (inorganic plus organic) was determined by atomic absorption spectrophotometer. Mean (± SE) levels of arsenic in drinking water, feed (dry weight) and excreta (dry weight) were 80.4 ± 5.5 µg/L, 119.0 ± 4.7 µg/kg and 1221.8 ± 58.3 µg/kg, respectively. In tissues (wet weight), highest arsenic concentration (µg/kg) was in skin (218.8 ± 11.7), followed by liver (102.1 ± 8.0), lung (96.3 ± 5.6), kidney (88.2 ± 7.5) and thigh muscle (67.8 ± 5.1). Arsenic in broiler meat was below the maximum tolerable limits for humans. Accumulations of arsenic in tissues and excreta were boosted with the relative increment of arsenic in drinking water and feed. High arsenic in excreta could be an environmental issue in Bangladesh.",
Arsenic,1017484,"Role of DNA polymerase beta in the genotoxicity of arsenic Abstract: Arsenic, an important hazard in the environment, is associated with human cancer and other degenerative diseases. However, the mechanisms underlying arsenic hazardous effects remain unclear. It has been reported arsenic exposure can result in increased cellular reactive oxygen species and oxidative DNA damage. This suggests DNA base excision repair (BER), the major pathway for repairing oxidative DNA damage, may be involved in combating arsenic hazardous effects. As a critical repair enzyme in BER, DNA polymerase beta (Pol ?) might play an essential role in reducing arsenic toxicity. To test this hypothesis, we evaluated arsenic-induced cytotoxic and genotoxic effects under Pol ? deficiency. Our results demonstrated that the viability of Pol ?-deficient mouse embryonic fibroblasts was much lower than that of Pol ? wild-type cells after treatment with arsenite (As(3+) ). An increased level of DNA damage and significantly delayed arsenite-induced DNA damage repair in Pol ?-deficient cells indicated reduced repair of DNA lesions under Pol ? deficiency. This was consistent with the increase in the frequency of micronuclei (MN), an indicator of chromosomal breakage, which was also observed in Pol ?-deficient cells treated with arsenite. In contrast, cells harboring overexpressed Pol ? resulted in a lower level of DNA damage and MN than Pol ? wild-type cells, indicating overexpression of the enzyme can combat arsenic-induced genotoxic effects. In conclusion, our results indicate an important role for Pol ? in repairing arsenite-induced DNA damage and maintaining chromosomal integrity and further suggest deficiency of BER may be involved in arsenic genotoxicity and carcinogenicity.",
Arsenic,2064264,"A comparison of epididymectomy with vasectomy reversal for the surgical treatment of postvasectomy pain syndrome Abstract: <strong>PURPOSE: </strong>To compare the outcome of epididymectomy and vasectomy reversal (VR) in patients with postvasectomy pain syndrome (PVPS) who required surgical treatment.<br /><br /><strong>METHODS: </strong>A total of 50 patients with PVPS who underwent epididymectomy or VR between January 2000 and January 2010 were included retrospectively. Of these, 36 (72.0 %) patients completed the study questionnaire. These 36 patients completed the questionnaire either during attendance at the outpatient clinic or during a telephone interview. Twenty patients (22 cases) underwent epididymectomy, and sixteen patients (17 cases) underwent VR. Analyses were performed for (1) preoperative clinical findings, (2) preoperative and postoperative visual analogue pain scale (VAPS) scores, (3) patency and pregnancy rate in VR group, and (4) patient satisfaction with surgical treatment.<br /><br /><strong>RESULTS: </strong>The mean age was 48.28 ± 11.27 years, and the mean period of follow-up was 3.58 years (0.15-10.03). The mean VAPS score was 6.78 ± 0.93 preoperatively and 1.13 ± 0.72 postoperatively (p &lt; 0.001). The difference in the mean preoperative and postoperative VAPS scores was 6.00 ± 1.34 (3-8) in the epididymectomy group and 5.50 ± 1.03 (4-8) in the VR group. However, this difference was not statistically significant (p = 0.227). No significant difference in satisfaction with surgical outcome was observed between the epididymectomy and the VR groups (p = 0.124).<br /><br /><strong>CONCLUSIONS: </strong>In PVPS patients requiring surgical treatment, no significant difference was observed between the epididymectomy and VR groups in either the reduction in pain or the degree of patient satisfaction with surgical outcome. Selection of the optimal surgical procedure may be dependent on specific patient characteristics.",
Arsenic,2149327,Best Practice Guides on Metals and Related Substances in Drinking Water Hybrid processes Abstract: ,
Arsenic,1346787,"PI3K/Akt/JNK/c-Jun signaling pathway is a mediator for arsenite-induced cyclin D1 expression and cell growth in human bronchial epithelial cells Abstract: Arsenite exposure is associated with an increased risk of human lung cancer. However, the molecular mechanisms underlying the arsenite-induced human lung carcinogenesis remain elusive. In this study, we demonstrated that arsenite upregulates cyclin D1 expression/activity to promote the growth of human bronchial epithelial Beas-2B cells. In this process, the JNKs (c-Jun N-terminal kinases)/c-Jun cascade is elicited. The inhibition of JNKs or c-Jun by chemical or genetic inhibitors blocks the cyclin D1 induction mediated by arsenite. Furthermore, using a loss of function mutant of p85 (Deltap85, a subunit of PI3K) or dominant-negative Akt (DN-Akt), we showed that PI3K and Akt act as the upstream regulators of JNKs and c-Jun in arsenite-mediated growth promotion. Overall, our data suggest a pathway of PI-3K/Akt/JNK/c-Jun/cylin D1 signaling in response to arsenite in human bronchial epithelial cells.",
Arsenic,2298734,"Serum albumin retains independent prognostic significance in diffuse large B-cell lymphoma in the post-rituximab era Abstract: Serum albumin (SA) has been shown to be a prognostic marker in many hematological malignancies and in diffuse large B-cell lymphoma (DLBCL) prior to chemo-immunotherapy. SA may be a surrogate for age, comorbid status, and disease severity. Here, we aimed to assess whether SA can be an independent prognostic marker in patients with newly diagnosed DLBCL treated with rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisone (R-CHOP). Patients who presented at the Moffitt Cancer Center from 2007 to 2010 for DLBCL diagnosis or treatment were identified using our institutional database. Clinical and treatment data were recorded, including SA levels at diagnosis. Survival time was estimated using the Kaplan-Meier method, with Cox proportional hazard model used to identify potential risk factors for time-to-event data. From 295 identified patients, 171 were excluded for not having primary treatment at our institution or not having R-CHOP treatment. In 124 included patients (mean age at diagnosis of 58 years, 91 % Caucasian), 25 % were categorized as poor by the revised International Prognostic Index. Overall and progression-free survival at 4 years were 65 % (95 % CI 57-75) and 58 % (95 % CI 0.49-0.69), respectively. Using multivariate analysis, we found that the hazard index of death of patients with SA ?3.7 g/dL was 26 % (95 % CI 13-53) of the hazard for those patients who had SA &lt;3.7 g/dL when controlling for the revised International Prognostic Index risk and initial lymphocyte count. Our study shows that SA ?3.7 g/dL is an independent prognostic marker in DLBCL patients treated with R-CHOP.",
Arsenic,710993,"Multi-trace elements level in drinking water and the prevalence of multi-chronic arsenical poisoning in residents in the west area of Iran Abstract: First, we determined the levels of 8 trace elements (As, Se, Hg, Cd, Ag, Mn, Cr and Pb) in 530 village drinking water sources by graphite furnace or flame atomic absorption spectroscopy method, in Kurdistan Province in the west of Iran. The results showed that the level of As, Cd and Se in 28 village drinking water sources exceeded WHO or National Standard limits. The levels of concentration of arsenic in drinking water ranged from 42 to 1500microg/L. Then in a cross-sectional survey, 587 people from 211 households were chosen for clinical examinations of multi-chronic arsenical poisoning including pigment disorders, keratosis of palms and soles, Mee's line in fingers and nails and the gangrene as a systemic manifestation. Of 587 participants, 180 (30.7%) participants were affected by representing the type of chronic arsenical poisoning. The prevalence of Mee's line, keratosis, and pigment disorders were 86.1%, 77.2% and 67.8% respectively. Therefore, the prevalence of Mee's line between inhabitants was higher than the other disorders. The results show a strong linear relationship between arsenic exposure and occurrence of multi-chronic arsenical poisoning (R(2)=0.76). The association between age for more than 40 years and gender for more than 60 years with chronic arsenical poisoning is significant (p&lt;0.05). Also, there is a relationship between subjects who were affected with disorders and duration of living in the village. Except for gangrene disorder, the odds ratio of prevalence of other disorders with arsenic exposure level in drinking water show a highly significant relationship between arsenic content and the risk of chronic disorders (p&lt;0.01). These results confirm the need to further study trace elements in drinking waters, food products and other samples in this area and the relationship to other chronic diseases arising out of arsenicosis.",
Arsenic,1345959,"Antioxidative mechanisms on selenium accumulation in Pteris vittata L., a potential selenium phytoremediation plant Abstract: ",
Arsenic,446845,"Evaluation of status of toxic metals in biological samples of diabetes mellitus patients Abstract: There is accumulating evidence that the metabolism of several trace elements is altered in diabetes mellitus and that these nutrients might have specific roles in the pathogenesis and progress of this disease. The aim of present study was to compare the level of toxic elements, lead (Pb), cadmium (Cd), and arsenic (As) in biological samples (whole blood, urine, and scalp hair) of patients having diabetes mellitus type-2 age ranged (31-60) (n = 238), with those of age matched non-diabetics (ND) as control subjects (n = 196), of both genders. The concentrations of elements were measured by means of an atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy was checked by conventional wet acid digestion method and using certified reference materials. The overall recoveries of all elements were found in the range of 98.1-99.4% of certified values. The results of this study showed that the mean values of Pb, Cd and, As were significantly higher in scalp hair samples of smoker and non-smoker diabetic patients as compared to control subjects (p < 0.001). The concentration of understudy toxic metals was also high in blood and urine samples of DM patient but difference was more significant in smoker DM patients. These results are consistent with those obtained in other studies, confirming that toxic metals may play a role in the development of diabetes mellitus. (C) 2008 Elsevier Ireland Ltd. All rights reserved.",
Arsenic,1252829,"Arsenic In Seafood: What Percentage Of The Total Is Inorganic Arsenic? Abstract: One of the most significant sources of human exposure to arsenic is food, with the highest arsenic concentrations found in seafood. In most seafood, organic forms of arsenic, mainly arsenobetaine, predominate (80?99%); however, other arsenicals, both inorganic and organic, may also be present. Arsenobetaine is not considered toxic, but inorganic arsenic is toxic and carcinogenic. Consequently, the speciation of arsenic in seafood is a critical consideration for estimating human health risk from seafood consumption. Commonly, only the total arsenic concentrations are available. For estimating human cancer and non-cancer risks, an approximation is needed for the percent of the total arsenic that is inorganic. A survey and evaluation of the data on arsenic speciation in various types of seafood was performed in order to determine published concentrations of total arsenic and inorganic arsenic in finfish, aquatic invertebrates, and seaweed. Sources of data included the published literature and EPA documents, and covered seafood worldwide, as well as seafood from specific US sites. A goal of this survey was to determine if default values could be derived for the percent inorganic arsenic in various types of seafood. While average percent inorganic arsenic values typically are <10% for fish and shellfish, the percent inorganic arsenic values for individual samples of a particular type of fish or shellfish can vary widely from not detected to nearly 30%. Frequently, the quality of the data was not documented and the number of samples limited. In seaweed samples, the percent inorganic arsenic values vary even more widely, from <1% to 60%. Data were not adequate to determine whether the percent inorganic arsenic differs in seafood from contaminated versus uncontaminated areas. This literature review indicates that a nation-wide default that accurately characterizes the percent inorganic arsenic in fish, shellfish, or seaweed is not supported by the available published data.",
Arsenic,2064147,"Residue Substitutions Near the Redox Center of Bacillus subtilis Spx Affect RNA Polymerase Interaction, Redox Control, and Spx-DNA Contact at a Conserved cis-Acting Element Abstract: ",
Arsenic,2279344,"Phosphate interference during in situ treatment for arsenic in groundwater Abstract: Contamination of groundwater by arsenic is a problem in many areas of the world, particularly in West Bengal (India) and Bangladesh, where reducing conditions in groundwater are the cause. In situ treatment is a novel approach wherein, by introduction of dissolved oxygen (DO), advantages over other treatment methods can be achieved through simplicity, not using chemicals, and not requiring disposal of arsenic-rich wastes. A lab-scale test of in situ treatment by air sparging, using a solution with approximately 5.3 mg/L ferrous iron and 200 ?g/L arsenate, showed removal of arsenate in the range of 59%. A significant obstacle exists, however, due to the interference of phosphate since phosphate competes for adsorption sites on oxidized iron precipitates. A lab-scale test including 0.5 mg/L phosphate showed negligible removal of arsenate. In situ treatment by air sparging demonstrates considerable promise for removal of arsenic from groundwater where iron is present in considerable quantities and phosphates are low.",
Arsenic,1027739,"Altered urinary porphyrin excretion in a human population chronically exposed to arsenic in Mexico Abstract: 1. A detailed study of the urinary excretion pattern of porphyrins in humans chronically exposed to As via drinking water was performed using high performance liquid chromatography (HPLC) 2. Thirty-six individuals (15 men and 21 women) were selected from a town which had 0.400 mg L-1 of As in drinking water. The control group consisted of thirty-one individuals (13 men and 18 women) whose As concentration in drinking water was 0.020 mg L-1. 3. The major abnormalities in the urinary porphyrin excretion pattern observed in arsenic-exposed individuals were: (a) significant reductions in coproporphyrin III excretion resulting in decreases in the COPRO III/COPRO I ratio, and (b) significant increases in uroporphyrin excretion. Both alterations were responsible for the decrease in the COPRO/URO ratio. 4. No porphyrinogenic response was found in individuals with urinary As concentrations below 1,000 micrograms of As g-1 of creatinine. However, as arsenic concentrations exceeded this value, the excretion of porphyrins (except coproporphyrin III) increased proportionally. 5. The prevalence of clinical signs of arsenicism showed a direct relationship to both As concentration in urine and time-weighted exposure to As. A direct relationship between time-weighted exposure and alterations in urinary porphyrin excretion ratios was also observed. 6. The alterations found are compatible with a lower uroporphyrinogen decarboxylase activity in arsenic-exposed individuals. However, the similarities in the urinary porphyrin excretion pattern between As-exposed individuals and Dubin-Johnson syndrome patients suggest that impairments in the excretion of coproporphyrin isomers may also contribute to the pattern observed.",
Arsenic,1278631,Mathematical models to predict soil heavy metal toxicity in the 2012 Olympic site Abstract: ,
Arsenic,1017627,"Cytogenetic status in newborns and their parents in Madrid: The BioMadrid study Abstract: Monitoring cytogenetic damage is frequently used to assess population exposure to environmental mutagens. The cytokinesis-block micronucleus assay is one of the most widely used methods employed in these studies. In the present study we used this assay to assess the baseline frequency of micronuclei in a healthy population of father-pregnant woman-newborn trios drawn from two Madrid areas. We also investigated the association between micronucleus frequency and specific socioeconomic, environmental, and demographic factors collected by questionnaire. Mercury, arsenic, lead, and cadmium blood levels were measured by atomic absorption spectrometry. The association between micronucleated cell frequency and the variables collected by questionnaire, as well as, the risk associated with the presence of elevated levels of metals in blood, was estimated using Poisson models, taking the number of micronucleated cells in 1,000 binucleated cells (MNBCs) as the dependent variable. Separate analyses were conducted for the 110 newborns, 136 pregnant women, and 134 fathers in whom micronuclei could be assessed. The mean number of micronucleated cells per 1,000 binucleated cells was 3.9, 6.5, and 6.1 respectively. Our results show a statistically significant correlation in MNBC frequency between fathers and mothers, and between parents and newborns. Elevated blood mercury levels in fathers were associated with significantly higher MNBC frequency, compared with fathers who had normal mercury levels (RR:1.21; 95%CI:1.02-1.43). This last result suggests the need to implement greater control over populations which, by reason of their occupation or life style, are among those most exposed to this metal.",
Arsenic,1344953,CHROMOPHORE SERVING AS A BASIS FOR THE DETERMINATION OF ARSENIC BY SILVER DIETHYLDITHIOCARBAMATE Abstract: ,
Arsenic,523773,"The Metabolic Syndrome: A Modern Plague Spread by Modern Technology Abstract: Malnutrition and infectious disease represent the most common health threats facing the developing world. However, increasing technological developments and the expansion of western culture have contributed to the increasing prevalence of the metabolic syndrome. The epidemiologic significance and potential costs to governmental health care systems of an increasing incidence of metabolic syndrome could become high. The role of environmental influences that lead to the development of the metabolic syndrome needs to be explored. Because the metabolic syndrome becomes more common as nations develop, investigations into the ramifications of this disease often come too late.",
Arsenic,1343351,"Specific panicle responses resulting from MSMA-induced straighthead sterility in rice Abstract: Straighthead is a physiological disorder of rice causing sterility. A particular characteristic of straighthead is panicles that remain upright because of the light weight of the unfilled grains, the hulls of which may be distorted into a crescent or parrot-beak shape. Monosodium methanearsenate (MSMA) was used in this study, to induce straighthead-like sterility symptoms in rice. Rating scales were developed to quantify the specific symptoms of straighthead (grain distortion, rachis curvature, panicle exsertion, and panicle weight), which were used to examine MSMA-induced straighthead in a greenhouse setting. Different rice cultivars were surveyed for their specific responses to MSMA, to identify targets for focus in rice breeding that differ in their responses. MSMA altered the pattern of anthesis so that flowering continued for a longer period of time although the initial flowering time and total panicle number were not affected. Early flowering panicles were less affected by MSMA than later flowering panicles. While all previous studies of MSMA-induced straighthead used MSMA applied at or before planting, a time course of MSMA application showed a time point for application at about the V4 (4-leaf) stage when the sterility symptoms were reduced and then an interval of time from about V6 to V8 when applications resulted in symptoms more severe than application at planting. A greenhouse temperature study demonstrated that lowering the temperature of the roots reduced the severity of the responses. MSMA is valuable as a trigger to induce a set of sterility symptoms so that the underlying physiological, biochemical, and genetic causes can be studied, and which may have implications for other sterility conditions.",
Arsenic,2088593,"Genetic diversity and molecular evolution of the major human metapneumovirus surface glycoproteins over a decade Abstract: <strong>BACKGROUND: </strong>Human metapneumovirus (HMPV) is a recently discovered paramyxovirus that is a major cause of respiratory infections worldwide.<br /><br /><strong>OBJECTIVES: </strong>We aim to describe the molecular evolution of the HMPV F (fusion) and G (attachment) surface glycoproteins because they are targets for vaccines, monoclonal antibodies and antivirals currently in development.<br /><br /><strong>STUDY SETTING: </strong>Nasopharyngeal aspirates were collected in children &lt;3 years old with acute respiratory infection in Quebec City during 2001-2010. HMPV-positive samples (n=163) underwent HMPV-F and -G gene sequencing. Furthermore, HMPV-F (n=124) and -G (n=217) sequences were obtained from GenBank and other studies. Evolutionary analyses (phylogenetic reconstruction, sequence identity, detection of recombination and adaptive evolution) were computed.<br /><br /><strong>RESULTS: </strong>Sequences clustered into 5 genetic lineages (A1, A2a, A2b, B1 and B2). Multiple lineages circulated each year in Quebec City. With the exception of B1, each of the 5 subgroups was the predominant lineage during ?1 season. The A1 lineage was not detected since 2002-2003 in our local cohort. There was no evidence of inter- or intragenic recombination. HMPV-F was highly conserved, whereas HMPV-G exhibited greater diversity. HMPV-F demonstrated strong evidence of purifying selection, both overall and in an abundance of negatively selected amino acid sites. In contrast, sites under diversifying selection were detected in all HMPV-G lineages (range, 4-15), all of which were located in the ectodomain.<br /><br /><strong>CONCLUSIONS: </strong>Predominant circulating HMPV lineages vary by year. HMPV-F is highly constrained and undergoes significant purifying selection. Given its high genetic variability, we found a modest number of positively selected sites in HMPV-G.",
Arsenic,1023798,"Hormesis effect of trace metals on cultured normal and immortal human mammary cells Abstract: An in vitro study was conducted to determine the effects of variable concentrations of trace metals on human cultured mammary cells. Monolayers of human mortal (MCF-12A) and immortal (MDA-MB231) mammary epithelial cells were incubated in the absence or presence of increasing concentrations of arsenic (As), mercury (Hg) and copper (Cu) for 24-h, 72-h, 4-d, and 7-d. The MTT assay was used to assess viability for all time periods and cell proliferation was monitored for 4-d and 7-d studies. Monolayers were also labeled with rhodamine-110 (R-6501), Sytox green, and Celltiter blue fluorescent dyes as indicators for intracellular esterase activity, nucleic acid staining, and cell reduction/viability, respectively. Total incubation time with chemical plus dyes was 24 h. For 24-h and 72-h studies, cells were seeded in 96-well plates, after which confluent monolayers were exposed to increasing concentrations of chemicals. For 4-d and 7-d studies, cells were seeded in 12-well plates at 1/3 confluent density (day 0) and exposed to increasing concentrations of metals on day 1. All cells were counted on days 4 and 7. In addition, test medium was removed from select groups of cultures on day 4, replaced with fresh medium in the absence of chemical (recovery studies), and assays were performed on day 7 as above. The data suggest that there is a consistent protective and/or stimulating effect of metals at the lowest concentrations in MCF-12A cells that is not observed in immortal MDA-MB231 cells. In fact, cell viability of MCF-12A cells is stimulated by otherwise equivalent inhibitory concentrations of As, Cu, and Hg on MDA-MB231 cells at 24-h. Whereas As and Hg suppress proliferation and viability in both cell lines after 4-d and 7-d of exposure, Cu enhances cell proliferation and viability of MCF-12A cells. MDA-MB231, however, recover better after 4-days of toxic insult. In addition, nutritional manipulation of media between the cell lines, or pretreatment with penicillamine, did not alter the hormesis effect displayed by MCF-12A. Growth of these cells however was not maintained in the alternative medium. The study demonstrates that a hormesis effect from trace metals is detectable in cultured mammary cells; fluorescent indicators, however, are not as sensitive as cell proliferation or MTT in recognizing the subtle responses. Also, sensitivity of mammary cells to lower concentrations of Cu, a biologically important trace metal, may play an important role in controlling cellular processes and proliferation. The ability to detect this in vitro phenomenon implies that similar processes, occurring in vivo, may be responsible for the development, induction, or enhancement of human cancers.",1
Arsenic,83967,"Effect of arsenic, cadmium and lead on the induction of apoptosis of normal human mononuclear cells Abstract: The aim of this work was to investigate the effect of cadmium, lead and arsenic on the apoptosis of human immune cells. Peripheral blood mononuclear cells (MNC) were incubated with increasing concentrations of these metals and then cellular apoptosis was determined by flow cytometry and by DNA electrophoresis. We found that arsenic induced a significant level of apoptosis at 15 microM after 48h of incubation. Cadmium had a similar effect, but at higher concentrations (65 microM). In addition, cadmium exerted a cytotoxic effect on MNC that seemed to be independent of the induction of apoptosis. In contrast, concentrations of lead as high as 500 microM were nontoxic and did not induce a significant degree of apoptosis. Additional experiments showed that arsenic at concentrations as low as 1.0 microM had a significant pro-apoptotic effect when cells were cultured in the presence of this pollutant for more than 72. Non-T cells were more susceptible than T lymphocytes to the effect of arsenic and cadmium. Interestingly, MNC from children chronically exposed to arsenic showed a high basal rate of apoptosis and a diminished in vitro sensibility to this metalloid. Our results indicate that both arsenic and cadmium are able to induce apoptosis of lymphoid cells, and suggest that this phenomenon may contribute to their immunotoxic effect in vivo.",
Arsenic,2278393,"Avaliação do tratamento sob pressão de postes de Eucalyptus saligna e Eucalyptus cloeziana com CCA-C Abstract: This study aims to evaluate the influence of pressure and time in the penetration and retention of chromated copper arsenate solution (CCA-C) in Eucalyptus saligna and Eucalyptus cloeziana wood poles. The treatments were performed in a horizontal autoclave using a preservative solution of CCA-C and Bethell method. The parameters of the treatments were: initial vacuum of 600 mmHg for 30 minutes, pressure of 10 kgf/cm2 or 12 kgf/cm2 for 60, 90 and 120 minutes and final vacuum of 600 mmHg for 15 minutes. After the impregnation, three wood poles were randomly selected for the analysis of CCA-C penetration and retention. The results showed that the penetration was classified as deep/irregular in the most of poles for both species. Only treatment with pressure of 12 kgf/cm2 for 120 minute showed mean value of retention (9.9 kgf/cm2) higher than the mean value required by NBR 16202:2013 (ABNT, 2013). On the other hand, all the mean values of retention in Eucalyptus cloeziana poles were lower than the mean value required in the standard aforementioned.",
Arsenic,1026442,"Chronic arsenic poisoning in drinking water in Inner Mongolia and its associated health effects Abstract: Since 1990, a large number of people have been experiencing various health problems from drinking arsenic contaminated water (50-1860 microg/L) in 13 counties of Inner Mongolia, China, most of which are located in the Hetao Plain area. It is calculated that 411,243 people are currently at risk from arsenic poisoning. Clinical and epidemiological investigations were carried out on 13,021 people to ascertain the nature and degree of morbidity that occurred due to chronic arsenic toxicity. In all of the studied patients, 22% had typical hyperkeratosis on the palms or soles and some had raindrop-like hyperpigmentation and depigmentation on the trunk. Other data recorded included subjective and objective symptoms, such as chronic cough (35.0%) and insomnia (37.5%). During physical checkups of 680 villagers in arsenic affected areas, liver function tests showed elevated globulin levels in 6.8% (P value=0.006) of the subjects. Neurotoxicity manifesting as loss of hearing 5.88 (P value=0.005), loss of taste 5.44% (P value=0.001), blurred vision 17.35% (P value=0.000), tingling and numbness of the limbs 33.53% (P value=0.000) and hypertension 8.09% (P value=0.000) were significantly higher in the arsenic affected villages and arsenic pollution also seemed to affect patients' social life and mental health. To solve the problem of arsenic exposure, the quality of drinking water needs to be improved by reducing the arsenic content. We also plan to carry out a survey to detect the incidence and types of cancer among this population.",
Arsenic,627528,"Induction of cyclin D1 by submicromolar concentrations of arsenite in human epidermal keratinocytes Abstract: Arsenic is a prevalent environmental carcinogen but arsenic is not directly mutagenic and the mechanism by which arsenite brings about oncogenic transformation is poorly understood. To gain insight into the oncogenic properties of arsenic, we studied the expression of cyclin D1 in cultured human epidermal keratinocytes treated with submicromolar concentrations of sodium arsenite. Arsenite at concentrations between 200 and 800 nM over a 3-day period brought about an increase in cell growth rate. Uptake of the vital stain, neutral red, arsenite at 200 and 400 nM concentrations brought about a parallel increase in cell viability over the same treatment period. Analysis of cell cycle parameters by flow cytometry showed that the growth stimulation was accompanied by a concomitant shift from the G1 into the S/G2 cell cycle compartment in the arsenite-treated cells. Real-time PCR analysis of cyclin D1 transcription showed that there was an induction of more than three-fold in cells exposed to 400 nM arsenite for 3 days. Quantitation of cyclin D levels in Western blots showed that arsenite treatment caused a time-dependent induction of cyclin D proteins representing an induction of about 2.0-fold after a 7 day treatment period. Electrophoretic mobility shift assays (EMSA) showed that arsenite also stimulated binding of the transcription factors, AP1 and CREBP to their respective binding motifs within 3 days. This supports a mechanism of oncogenesis based on persistent upregulation of D type cyclins leading to a concomitant loss of G1/S checkpoint control.",
Arsenic,628346,"The role of oxidative stress in hormesis induced by sodium arsenite in human embryo lung fibroblast (HELF) cellular proliferation model Abstract: Hormetic dose-response relationships induced by environmental agents are often characterized by a low-dose stimulation and a high-dose inhibition. The mechanisms underlying hormesis induced by environmental agents still remain an enigma; however, hormetic consequences may have significant implications for health risk assessments. To investigate the role of oxidative stress in hormetic phenomena associated with cell proliferation induced by sodium arsenite, the levels of reactive oxygen species (ROS), lipid peroxidation (LPO), and heat-shock proteins (HSP) and the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were measured in human embryo lung fibroblast (HELF) cells after treatment with sodium arsenite at various concentrations for differing times. Results showed that sodium arsenite induced significant cell proliferation at low concentrations (0.5 microM for 12, 24, and 48 h), but inhibited cell growth at high amounts (5 and 10 microM for 24 and 48 h), reflected as a beta concentration-response curve. Data indicated that the relationship between ROS levels and sodium arsenite exposure concentration displayed a positive correlation. It was found out that sodium arsenite at high concentrations induced LPO damage. The activities of SOD were enhanced at low metal concentrations but inhibited with high amounts in a concentration-dependent manner. Similarly, heat-shock protein 27 (HSP27) levels were increased by sodium arsenite of low concentrations with early exposure time (3, 6, and 12 h), but decreased with high metal concentrations with greater exposure time (24 and 48 h). Sodium arsenite decreased HSP70 expression at lower concentrations, but increased HSP70 expression at higher concentration. The results indicated that this cellular hormetic model of cell proliferation induced by sodium arsenite occurred in HELF cells, which may explain contradictory effects seen with this metal. Sodium arsenite at low concentrations induced enhanced ROS generation without cytotoxicity and a cellular protective effect. In contrast, sodium arsenite at high concentrations produced marked ROS formation, marked oxidative stress, and cellular damage, as evidenced by LPO.",
Arsenic,736233,"Molecular mechanisms of the diabetogenic effects of arsenic: inhibition of insulin signaling by arsenite and methylarsonous acid Abstract: Increased prevalences of diabetes mellitus have been reported among individuals chronically exposed to inorganic arsenic (iAs). However, the mechanisms underlying the diabetogenic effects of iAs have not been characterized. We have previously shown that trivalent metabolites of iAs, arsenite (iAs(III)) and methylarsonous acid (MAs(III)) inhibit insulin-stimulated glucose uptake (ISGU) in 3T3-L1 adipocytes by suppressing the insulin-dependent phosphorylation of protein kinase B (PKB/Akt).<br /><br /> Our goal was to identify the molecular mechanisms responsible for the suppression of PKB/Akt phosphorylation by iAs(III) and MAs(III).<br /><br /> The effects of iAs(III) and MAs(III) on components of the insulin-activated signal transduction pathway that regulate PKB/Akt phosphorylation were examined in 3T3-L1 adipocytes.<br /><br /> Subtoxic concentrations of iAs(III) or MAs(III) had little or no effect on the activity of phosphatidylinositol 3-kinase (PI-3K), which synthesizes phosphatidylinositol-3,4,5-triphosphate (PIP(3)), or on phosphorylation of PTEN (phosphatase and tensin homolog deleted on chromosome ten), a PIP(3) phosphatase. Neither iAs(III) nor MAs(III) interfered with the phosphorylation of 3-phosphoinositide-dependent kinase-1 (PDK-1) located downstream from PI-3K. However, PDK-1 activity was inhibited by both iAs(III) and MAs(III). Consistent with these findings, PDK-1-catalyzed phosphorylation of PKB/Akt(Thr308) and PKB/Akt activity were suppressed in exposed cells. In addition, PKB/Akt(Ser473) phosphorylation, which is catalyzed by a putative PDK-2, was also suppressed. Notably, expression of constitutively active PKB/Akt restored the normal ISGU pattern in adipocytes treated with either iAs(III) or MAs(III).<br /><br /> These results suggest that inhibition of the PDK-1/PKB/Akt-mediated transduction step is the key mechanism for the inhibition of ISGU in adipocytes exposed to iAs(III) or MAs(III), and possibly for impaired glucose tolerance associated with human exposures to iAs.",
Arsenic,1070380,"Study of heavy metal levels among farmers of Muda Agricultural Development Authority, Malaysia Abstract: Heavy metals, particularly cadmium, lead, and arsenic, constitute a significant potential threat to human health. This study was conducted to determine the levels of cadmium, lead, and arsenic in nail samples from farmers at Muda Agricultural Development Authority (MADA), Kedah, Malaysia, and evaluate factors that can contribute to their accumulations. A total of 116 farmers participated in this study. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze concentration of heavy metals in the nail samples and questionnaires were given to participants to get demographic, health status, and their agricultural activities data. In this paper, the level of heavy metals was within the normal range and varies according to demographic factors. We found that there were significant correlations between working period with level of lead and arsenic (r = 0.315 and r = 0.242, resp., P &lt; 0.01) and age with lead level (r = 0.175, P &lt; 0.05). Our findings suggested that agricultural activities could contribute to the accumulation of heavy metals in farmers. Hence, the control of environmental levels of and human exposure to these metals to prevent adverse health effects is still an important public health issue.",
Arsenic,68029,"Human studies do not support the methylation threshold hypothesis for the toxicity of inorganic arsenic Abstract: Inorganic arsenic (In-As) is an established human carcinogen. Methylation to monomethylarsonate (MMA) and dimethylarsinate (DMA) is believed to be the detoxification mechanism for In-As. Urinary measurement of In-As, MMA, and DMA is considered a good biological marker of internal dose to In-As, since it excludes other ingested forms of arsenic which are much less toxic, and because urinary excretion is the main form of elimination of In-As. A methylation threshold hypothesis for In-As has been proposed, stating that after exposure to In-As reaches a certain level or threshold, methylation capacity begins to decline, thus increasing the toxic effects of In-As. We investigated the validity of this hypothesis by analyzing the data from studies which measured urinary In-As, MMA, and DMA in different populations, ranging from background to high occupational and environmental exposure groups. We also present data from our study of a highly exposed population in California. Our analysis focused on the proportion of urinary In-As remaining in the unmethylated form [In-As/(In-As + MMA + DMA)]. The results indicate that epidemiological and experimental human data do not support the methylation threshold hypothesis. On average, 20-25% In-As remains unmethylated regardless of the exposure level. The wide range of interindividual variability in methylation capacity found in some studies warrants further investigation.",
Arsenic,1250964,"Phylogenetic and phenotypic analyses of arsenic-reducing bacteria isolated from an old tin mine area in Thailand Abstract: An agar plate screening assay was used to determine whether 100 arsenic-resistant bacterial isolates, previously obtained from arsenic-contaminated soils, had the ability to transform arsenite and arsenate. Ninety-five percent of the isolates were capable of reducing arsenate on agar plates. The isolates also grew in the presence of high concentrations of arsenite, but none of the bacterial isolates oxidized arsenite to arsenate under the growth conditions tested. About 14 % (13 of 95) of the tested isolates transformed high levels of arsenate (33-70 ?M) when tested using the molybdenum blue method. Partial sequence analysis of 16S rDNA genes indicated that the isolates belonged to two broad taxonomic groups: Firmicutes and Proteobacteria. Ten isolates were assigned to four species in the genus Bacillus, and three isolates belonged to two species in the genera Enterobacter and Ochrobactrum. Taken together these results indicate that phylogenetically diverse bacteria isolated from arsenic-contaminated soils in an old tin mine area in Thailand have the ability to transform arsenate to arsenite.",
Arsenic,1508544,"Synthesis and Properties of Arsenic(III)-Reactive Coumarin-Appended Benzothiazolines: A New Approach for Inorganic Arsenic Detection Abstract: The EPA has established a maximum contaminant level (MCL) of 10 ppb for arsenic (As) in drinking water requiring sensitive and selective detection methodologies. To tackle this challenge, we have been active in constructing small molecules that react specifically with As to furnish a new fluorescent species (termed a chemodosimeter). We report in this contribution, the synthesis and spectroscopy of two small-molecule fluorescent probes that we term ArsenoFluors (or AFs) as As-specific chemodosimeters. The AFs (AF1 and AF2) incorporate a coumarin fluorescent reporter coupled with an As-reactive benzothiazoline functional group. AFs react with As to yield the highly fluorescent coumarin-6 dye (C6) resulting in a 20-25-fold fluorescence enhancement at ? ? 500 nm with detection limits of 0.14-0.23 ppb in tetrahydrofuran (THF) at 298 K. The AFs also react with common environmental As sources such as sodium arsenite in a THF/CHES (N-cyclohexyl-2-aminoethanesulfonic acid) (1:1, pH 9, 298 K) mixture resulting in a modest fluorescence turn-ON (1.5- to 3-fold) due to the quenched nature of coumarin-6 derivatives in high polarity solvents. Bulk analysis of the reaction of the AFs with As revealed that the C6 derivatives and the Schiff-base disulfide of the AFs (SB1 and SB2) are the ultimate end-products of this chemistry with the formation of C6 being the principle photoproduct responsible for the As-specific turn-ON. It appears that a likely species that is traversed in the reaction path is an As-hydride-ligand complex that is a putative intermediate in the proposed reaction path.",
Arsenic,1247529,"As4S4 induced apoptosis in HeLa cells and its molecular mechanism Abstract: Objective: To investigate the As4S4 induced growth inhibition and apoptosis in HeLa cells and its possible relationship with cyclooxygenase- 2 ( COX- 2). Methods: HeLa cells were treated with various concentrations ( 7.5, 15, 30, 60 mg/ L) of As4S4 at different times ( 12, 24, 36, 48, 60 h). Cell growth was measured by MTT. Apoptosis was detected by double staining flow cytometry ( FCM). Levels of PGE2 were measured by radioimmunoassay. The expression of COX- 2 protein was examined by Western blot analysis. Results: After treated with different concentrations of As4S4, the growth of HeLa cells was suressed significantly in a dose- and time- dependent manner. The IC50 of 24 h was 30 mg/ L ( P < 0.01). As4S4 induced apoptosis with apoptosis rates at 8.13%- 62.36% by flow cytometry ( FCM) in a dose- dependent manners. The release of PGE2 was reduced in HeLa cells with the values being ( 70.56 +/- 2.03), ( 48.58 +/- 2.28), ( 29.25 +/- 1.57) and ( 18.02 +/- 1.04) respectively, significantly different compared with control group ( 3.15 +/- 0.01) ( P < 0.01). As4S4 also inhibited the activity and expression of COX- 2 in a dose dependent manner and down- regulated the expression of COX- 2 protein greatly. Conclusion: As4S4 could inhibit the proliferation and increase apoptosis in human HeLa cells. These effects may depend on the inhibition of the expression of COX- 2 and PGE2 by As4S4.",
Arsenic,1355552,Sublethal arsenic exposure alters focal adhesion and cytoskeletal organization in cultured H9C2 cells Abstract: ,
Arsenic,2064205,"Single and combined effects of cadmium and arsenate in Gammarus pulex (Crustacea, Amphipoda): Understanding the links between physiological and behavioural responses Abstract: This study aimed at investigating the individual and interactive effects of cadmium (Cd) and arsenate (AsV) in Gammarus pulex (Crustacea, Amphipoda) through the use of several biomarkers. Individuals were exposed for 240h to two concentrations of AsV or Cd alone, and all the possible binary mixtures of these concentrations of AsV and Cd in a complete factorial design. The pattern of the biomarkers' responses to Cd and AsV alone or in mixture was similar in Gammarus pulex, even if the response intensity varied depending on the tested conditions. G. pulex responded to contamination with increased mobilization of the detoxification systems [i.e. ?-glutamyl-cystein ligase activity (GCL), reduced glutathione content (GSH) and metallothionein concentrations (MT)]. This response seems to imply changes in energy reserve utilization (total lipids and proteins are used prior to glycogen reserves), but also a possible energy reallocation from locomotion to detoxification processes. The observed increase in lipid peroxidation could be relied to the increasing gammarid mortality, despite the higher mobilization of detoxification systems. Even if the outcome of the complex interactions between AsV and Cd remains difficult to unravel, such studies are critically important for better assessing the effects of stressors on organisms, populations and communities in a multi-contamination context of ecosystems.",
Arsenic,2337101,"Trace elements pollution from an abandoned mine and factors affecting antimony concentrations in the Dahimine wadi bank soils (Northeast Algeria) Abstract: The Dahimine wadi starts on a mountain side (Djebel hamimat) where an abandoned antimony mine exists. A previous study indicated great amounts of antimony (Sb) in soils surrounding mine spoils. The objective of this research is, on one hand, to assess the extent of the contamination and/or pollution by Sb and other trace elements to a wadi part situated lower than the mining area. On the other hand, the aim is to determine factors that play a role in determining antimony accumulation in the studied wadi bank soils. For this purpose, several physic-chemical properties (particle size distribution, CaCO3, organic matter (OM), total phosphorus (TP), total nitrogen (TN), exchangeable sodium (ENa), exchangeable calcium (ECa), exchangeable magnesium (EMg) and exchangeable potassium (EK) contents, cation exchange capacity (CEC), pH and electrical conductivity (EC) and aqua regia extractable chemical elements Sb, As, Pb, Co, Cu, Cr, Cd, Zn, Fe, Mg, Ca and K were determined. Results show that the majority of soils are severely polluted by Sb and As whose maximal concentrations were respectively 2600 mg.kg(-1) and 450 mg.kg(-1). They are moderately contaminated by Pb and Zn that respectively reach 145 mg.kg(-1) and 324 mg.kg(-1). The results of forward stepwise regression analysis show that the most significant variables that explain the soil Sb concentration are, positively, As, ENa, sand, Cd and OM, and, negatively, EK and Zn. These results show that the Sb behaviour differs, partly, from that of the other trace elements, especially in calcareous and semi-arid environments.",
Arsenic,2347654,"Effect of groundwater-lake interactions on arsenic enrichment in freshwater beach aquifers Abstract: Field measurements combined with numerical simulations provide insight into the water exchange, groundwater flow and geochemical processes controlling the mobility of arsenic (As) in freshwater beach aquifers. Elevated dissolved As (up to 56 µg/L) was observed 1 - 2 m below the shoreline at two sandy beaches on Lake Erie, Ontario. Water and solid phase analyses suggest that Fe (hydr)oxides present below the shoreline accumulate As, creating a risk of high As in the beach aquifer. Groundwater flow simulations combined with vertical hydraulic gradient measurements suggest wave-induced flow recirculations across the groundwater-lake interface are significant. These recirculations, which vary with wave intensity and lake water level fluctuations, set up redox and pH gradients where Fe precipitates and subsequently sequesters As. The elevated As concentrations observed at both beaches, combined with the distribution of other dissolved species, suggest that the As enrichment may be naturally-occurring. Regardless of the As source, the interacting hydrologic and geochemical processes revealed may have important implications for the flux of As, and also other oxyanions such as phosphate, across the groundwater-lake interface in nearshore areas of the Great Lakes.",
Arsenic,1148115,"Arsenic Activates Nadph Oxidase Through CDC42 And Their Involvement In Actin Filament Remodeling And Cell Motility In Endothelial Cells Abstract: Although arsenic is a human cancinogen, the molecular mechanisms of its action remain to be understood. By stimulating mouse endothelial cell lines (SVEC4-10) with 10 ?M arsenic, we found that arsenic induced activation of NADPH oxidase as determined by the nitroblue tetrazolium test. Using confocal microscopy, the generation of O-. 2 and H2O2 was observed to be increased in SVEC4-10 cells after exposure to arsenic. We also found that arsenic activated Small Rho GTPase CDC42. Disruption of CDC42 with a dominant negative CDC42 abolished arsenic-induced activation of NADPH oxidase and subsequent generation of O-. 2 and H2O2, suggesting that CDC42 may mediate the effects of arsenic on NADPH oxidase. Furthermore, it was found that arsenic stimulation induced actin filament remodeling and increased cell motility in SVEC4-10 cells. These changes were abrogated by either disruption of CDC42 or inhibition of NADPH oxidase, indicating that the cell signaling changes induced by arsenic are relevant to these cellular functions. Taken together, the data imply that arsenic may promote motility-dependent metastasis of cancer cells through CDC42, NADPH oxidase and reactive oxygen species.",
Arsenic,1519205,"Ultrafine particle and fine trace metal (As, Cd, Cu, Pb and Zn) pollution episodes induced by industrial emissions in Huelva, SW Spain Abstract: Urban air quality impairment by ultrafine particles has become a matter of concern due to the adverse effects on human health. Most of the studies of ultrafine particles in urban air quality have focused on vehicle exhaust emissions. We studied how industrial emissions contribute to ultrafine particle concentrations in downwind urban ambient air. This research is based on experimental data collected in the ambient air of the industrial city of Huelva (SW Spain) over April 2008-December 2009 period (particle number, gaseous pollutants and black carbon concentrations and levels and chemical composition of PM10 and PM2.5 with daily and hourly resolution). This city is affected by emissions from the second largest Cu-smelter in Europe, phosphoric acid and fertilizer production plants and an oil refinery and petrochemical plant. Industrial emissions are the main cause of ultrafine particle episodes. When vehicle exhaust emissions are the main source, ultrafine particles typically show (24-h mean) concentrations within the range 14,700-5000 cm(-3) (50th-lst), with 60% of these linked to this source and 30% to industrial emissions. In contrast, when daily mean levels of N are within the range 50,000 -25,500 cm(-3) (100th-70th), industrial and vehicle exhaust emissions accounted for 49 and 30%, respectively. High concentrations of toxic trace metals (As, Cu, Cd, Zn and Pb) were recorded when the study city suffered fumigations of the Cu-smelter plumes (e.g. 10-25 ng m(-3) As, 1-2 ng m(-3) Cd and &gt;10(5) cm(-3) of ultrafine particles). Because of these industrial emissions, ultrafine particle concentrations during daylight are about two times higher than those observed in other European cities. Recently, ultrafine particle emissions in vehicle exhausts have been subject to limit values in a recent stage of the EURO standards. Industrial emissions should also be considered. (C) 2012 Elsevier Ltd. All rights reserved.",
Arsenic,2278451,"Coagulation with hydrolyzing metal salts: Mechanisms and water quality impacts Abstract: Coagulation is a critical—but highly complex—process in drinking water treatment. Variations in pH, temperature, source water composition, coagulant type, and other conditions collectively influence the process and confound efforts to quantitatively predict coagulation outcomes. Yet, qualitative understanding is possible through synthesis of the extensive literature. This review describes hydrolysis reactions of metal salts and summarizes variables that influence the characteristics of the resulting precipitates. Thereafter, properties of two key contaminants, turbidity and natural organic matter (NOM), are explored in the context of removal during coagulation. Finally, the significance of source water quality and co-occurring ions is described.",
Arsenic,1579322,"[T1 high-grade bladder cancer - value of second operation with prognostuic parameters of first operation: analysis of 167 cases] Abstract: We have evaluated the results of second transurethral resections of the bladder (TURB) after T1 high-grade bladder cancer over a 4.5-year period.From July 2007 to February 2012, 2172 TURB procedures were performed at our institution, of which 1130 were initial resections owing to primary tumour or relapse. Of these, 258 revealed T1 high-grade bladder cancer, and here we investigated tumour characteristics of the initial TURB and results of the second resection.The incidence of T1 high-grade tumours was 22.8% (N=258). Of 167 patients who underwent a second resection, tumour was found in 58.1% (97 of 167). Tumours were mostly multifocal (61.9%) and smaller than 3 cm (69.1%). Histology of the second resection revealed Ta low-grade in 8.4%, Ta high-grade in 16.2%, T1 high-grade in 19.8% and an upstaging to T2 and more in 6.6%. A significant association with the recurrence rate was found for the number of tumours at initial TURB: patients with multiple tumours at initial TURB had a recurrence rate of 69.0% compared with only 46.3% of patients with solitary tumour. For tumour-size and detrusor muscle in specimen a non-significant association was shown.T1 high-grade bladder cancers show a relevant rate of tumour at second TURB which confirms the clinical guidelines of the EAU. A significant association for a tumour-free second TURB in our data was shown for solitary tumours. A non-significant association was shown for tumour-size and when detrusor muscle was present in the specimen. Currently there is no data to determine the best time interval before second resection.",
Arsenic,1070318,"Subchronic exposure to arsenic inhibits spermatogenesis and down-regulates the expression of Ddx3y in testis and epididymis of mice Abstract: Arsenic (As) has been reported to exert toxic impact on the male reproductive system, but the fundamental mechanisms of male reproductive toxicity caused by As remains unclear. In this study, the effects of As on male reproductive system were investigated in adult mice given drinking water alone or containing 1, 2, 4 mg/L arsenic trioxide (As2O3) for 60 days. After the treatment, the weights of testis and epididymis were analyzed. The sperm quality, spermatogenesis, and histological alteration of the testis and epididymis were observed by microscope. Compared to untreated mice, the weights of testis and epididymis were reduced, sperm motility and the number of VII phase cells in the seminiferous epithelium section were decreased, sperm malformation ratio was increased, and histopathological alterations were observed in treated mice. Furthermore, to investigate the mechanisms of As-induced male reproductive toxicity, the expressions of Ddx3y gene, a Y-link gene important in spermatogenesis and sperm mature, and its protein in the testis and epididymis were examined by real-time RT-PCR, western blotting and immunohistochemistry. It was found that the gene and protein expression of Ddx3y in testis and epididymis were significantly down-regulated in As-exposed mice. These results showed that subchronic As exposure has detrimental effects on spermatogenesis and sperm development, and indicated that Ddx3y may be an important target gene of As and the down-regulated the expression of Ddx3y may be closely relate to male reproductive toxicity induce by As.",
Arsenic,2278242,"Arsenic toxicity in broiler chicks and its alleviation with ascorbic acid: A toxico-patho-biochemical study Abstract: To find out toxico-pathological effects of arsenic (As) and ameliorating effect of ascorbic acid (Vit C), broilers birds were administered 50 and 250 mg/kg arsenic and Vit C, respectively alone/in combination. As-treated birds exhibited severe signs of toxicity such as dullness, depression, increased thirst, open mouth breathing and watery diarrhea. All these signs were partially ameliorated with the treatment of Vit C. As-treated birds showed a significant decrease in serum total proteins while serum enzymes, urea and creatinine were significantly increased Alkaline phosphatase and lactate dehydrogenase completely whereas proteins, aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine were partial ameliorated in birds treated with As+Vit C as compared to As-treated and control birds. Pale and hemorrhagic liver and swollen kidneys were observed in As-treated birds. Histopathologically, liver exhibited congestion and cytoplasmic vacuolation while in kidneys, condensation of tubular epithelium nuclei, epithelial necrosis, increased urinary spaces, sloughing of tubules from basement membrane and cast deposition were observed in As-treated birds. Pathological lesions were partially ameliorated with the treatment of Vit C. It can be concluded that arsenic induces biochemical and histopathological alterations in broiler birds; however, these toxic effects can be partially attenuated by Vit C. (C) 2013 Friends Science Publishers",
Arsenic,1347248,"Reduced induction of HSP70 in PC12 cells during neuronal differentiation Abstract: Rat pheochromocytoma PC12 cells differentiate into nonreplicating neuronal cells with neurite extensions in response to nerve growth factor (NGF). To gain better understanding of the regulation of stress responses in neuronal cells, we examined the induction of HSP70, HSP70 mRNA, and heat shock factor 1 (HSF1) DNA-binding activity following treatment by heat shock or with sodium arsenite or amino acid analogue in PC12 cells treated with or without NGF. The induction of HSP70 and HSP70 mRNA following these stresses was diminished in the differentiated PC12 cells compared to the undifferentiated cells, whereas the HSF1 DNA-binding activity was enhanced in the differentiated PC12 cells. This phenomenon was characteristic of the differentiated neuronal cells rather than growth-arrested cells. Thus, neuronal cells appear to show an altered stress response depending on their differentiation state, and the diminished HSP70 expression in the differentiated neuronal cells may explain the sensitivity of neuronal cells to pathophysiological stressors.",
Arsenic,2064127,"The association of diabetes mellitus with subsequent internal cancers in the arsenic-exposed area of Taiwan Abstract: Background Epidemiological studies have shown that diabetes mellitus (DM) is associated with an increased risk of cancer. The aim of this study was to examine the association of diabetes with subsequent internal cancers in an arsenic-exposed area where the prevalence of diabetes is remarkably higher than in the general Taiwan population. Methods The southwestern cohort was recruited from blackfoot disease (BFD) endemic townships with high arsenic levels in their well water, while the northeastern cohort was recruited from four townships in the Lanyang Basin with low-to-moderate arsenic level in their well water. These two cohorts were combined and a total of 9525 subjects were recruited for the analysis. The disease status of the subjects, including diabetes, hypertension or dyslipidemia, was ascertained through linkage with the computerized Taiwan National Health Insurance (NHI) database, while the cancer status of the subjects was ascertained through linkage with National Cancer Registry and via the NHI database for major illness/injury certificates/catastrophic illness cards. The subjects were followed from study entry through December 31, 2009. Cox regression analysis with time-dependent DM status was used to determine the hazard ratios (HRs) and 95% confidence intervals (CIs) for developing internal malignancies. Results Diabetic patients had a 58% higher risk of any site internal cancer compared to non-DM individuals (HR, 1.58; 95% CI: 1.39–1.79) after adjusting for age, sex, education level, cigarette smoking, alcohol drinking, geographical location, cumulative arsenic exposure and history of hypertension or dyslipidemia. A significant association of DM with cancers of the stomach (HR, 1.75; 95% CI: 1.12–2.76), colon (HR, 1.76; 95% CI: 1.20–2.59), liver (HR, 2.46; 95% CI: 1.81–3.34), pancreas (HR, 2.80; 95% CI: 1.30–6.20) and lungs (HR, 1.35; 95% CI: 1.04–1.76) was observed. The association with lung, bladder and kidney cancer was largely confined to diabetic patients with arsenic level in consumed water ?500 ?g/L, while the association with other cancer sites did not show such an effect. With the adjustment of arsenic exposure, marked attenuation for the association was observed, suggesting high level arsenic exposure plays an important role in the development of diabetes mellitus and concomitantly lung, bladder and kidney cancer.",
Arsenic,8269,"Comparison of several methods for the determination of arsenic compounds in water and in urine Abstract: Several arsenic species (inorganic tri- or pentavalent arsenic, mono- and dimethylated arsonic acids) can be determined in water samples by electrothermal atomic absorption spectrometry after appropriate acidification procedures (concentrated HCl or a mixture HCl/HClO4/HBr) and extraction by toluene in the presence or absence of KI; the determination of aromatic derivatives and of arsenic thiol complexes needs a wet or dry ashing step. The procedures for water analysis are not directly applicable to urine samples; in the best conditions, total inorganic plus 85% on the average of the methylated arsenicals present in urine are measured after acidification with concentrated HCl and extraction by toluene in the presence of KI. Total arsenic content (including arsenic from marine origin) is measured only after a drastic mineralization step like MgO treatment at 600°C. The results obtained by the electrothermal atomic absorption technique and those obtained by neutron activation analysis are in excellent agreement. When the presence of arsenic of marine origin is suspected in urine, the analysis of inorganic arsenic and its metabolites is preferably performed by an arsine generation technique. The sum of inorganic arsenic and of its mono and dimethylated derivatives determined by such a technique is identical with the results obtained by electrothermal atomic absorption spectrometry after complete mineralization of the samples as long as no arsenic from marine origin is present. After oral ingestion of As2O3 by man, the urinary excretion of inorganic arsenic and its metabolites is important and rapid (approximately 60% are eliminated by the oral route with a half life of 30 h). While the excretion occurs in the form of inorganic species during the first hours following the ingestion, a methylating process is rapidly triggered and leads to a preponderant excretion of dimethylarsinic acid 1 day after ingestion. In the case of ingestion of seafood containing arsenic, the urinary excretion occurs at a higher rate (half life 18 h) apparently without transformation. The absence of interference of arsenic from marine origin and the capacity of measuring separately inorganic arsenic and its main urinary metabolites makes the arsine generation technique the best suited for the monitoring of workers exposed to inorganic arsenic. However, since the technique may sometimes be too elaborate and time-consuming for routine work, the biological monitoring of workers can be performed by determining total arsenic concentration in urine after mineralization with MgO. Samples with high arsenic content are then re-analyzed to distinguish between occupational exposure and ingestion of the organic arsenic present in marine organisms. This is carried out either by the arsine generation method or, if this technique is not available, by a direct extraction procedure in the presence of KI of a sample acidified with HCI. With the latter procedure, 85% of the methylated arsenic is measured on average without interference of arsenic from marine origin.",
Arsenic,1032911,"Arsenite induced sensitization and self-tolerance of Reuber H35 hepatoma cells Abstract: Our data show that a short incubation with arsenite (30-300 microM) induces a biphasic change in cellular sensitivity towards a second exposure to arsenite. A transient sensitization was followed by the development of self-tolerance. Sensitization was measured using the step-down protocol; i.e., application of a high dose of arsenite pretreatment (100 or 300 microM) followed immediately by incubation in a low dose of arsenite (1-30 microM), with extensive rinsing in between. Whereas no effect of 1 and 3 microM on cellular survival is observed without pretreatment, a large decrease in cell survival can be established when these low doses of arsenite are applied immediately after a 1 hr pretreatment with 100 or 300 microM arsenite. According to the step-down protocol, a high dose of toxic compounds is applied and is followed by prolonged incubation in a lower concentration of the initial toxic compound. This might be a more accurate model for studying the effects of toxic insults on cells and organisms in the manner in which they occur in their natural environment. The level of tolerance was determined by a 1 hr test treatment with 300 microM arsenite applied at different times after pretreatment. Using this fractionated treatment protocol, it was established that tolerance increases with the increasing time intervals between the sodium arsenite treatments, during the 6 hr studied. These observations suggest that sensitization gradually decreases, whereas tolerance develops. Furthermore, our data indicate that the condition of pretreatment determines the extent to which the early sensitivity increases, as well as the development of tolerance later on. A relatively high arsenite concentration leads to more sensitized cells, which are transformed into more tolerant cells in comparison with the effect of a lower arsenite concentration.",
Arsenic,2064243,"Second-Generation Everolimus-Eluting Stents Compared to First-Generation Drug-Eluting Stents in Patients Treated for Multivessel Disease Abstract: <strong>OBJECTIVE: </strong>This study aimed to compare the safety and efficacy of everolimus-eluting stents (EES) to first-generation drug-eluting stents (DES) in multivessel disease (MVD).<br /><br /><strong>BACKGROUND: </strong>Second-generation EES have demonstrated superiority over first-generation DES for single-vessel disease, although the merits of EES in MVD are less established.<br /><br /><strong>METHODS: </strong>A cohort of 1,285 patients (3,124 lesions) with ?2 diseased vessels were treated with either first-generation DES (n?=?1,002) or EES (n?=?283). The rates of death, myocardial infarction, target lesion revascularization, target vessel revascularization, definite stent thrombosis, and major adverse cardiac events (MACE), defined as the combined incidence of target vessel revascularization, death, and non-fatal myocardial infarction, were compared at 1 year.<br /><br /><strong>RESULTS: </strong>Baseline characteristics were similar except for a lower left ventricular ejection fraction and a lower incidence of stable angina pectoris in the first-generation DES group (P?=?0.001 and 0.013, respectively). At 1 year, the MACE rate was lower in the EES group (9.5P% vs. 15.7%; P?=?0.01). Multivariable analysis demonstrated that EES use predicted a higher chance of freedom from MACE at 1 year (hazard ratio 0.58 [0.38-0.87]; P?=?0.009; 95% confidence interval).<br /><br /><strong>CONCLUSIONS: </strong>The use of EES in patients with MVD is safe with signals for improved effectiveness compared to first-generation DES. Randomized trials comparing new-generation DES to coronary artery bypass grafting surgery are warranted.",
Arsenic,2279176,"Arsenic-induced hepatic toxicity and its attenuation by fruit extract of emblica officinalis (Amla) in mice Abstract: Arsenic a metalloid and environmental contaminated has been found to be associated with public health problems in the affected areas. It is naturally occurred in groundwater and its accumulation in plant and animals leads to toxicity in several tissues most notably hepatic organ. Arsenic exposures (3 mg/kg body weight/day for 30 days) in mice exhibited increased arsenic and Zn levels in hepatocytes associated with enhanced oxidative stress in hepatocytes while there were no significantly changes were observed in Cu level. An increase in the lipid peroxidation and decrease in the levels of reduced glutathione and activity of superoxide dismutase, catalase, and glutathione peroxidase were observed in arsenic treated mice as compared to controls. Arsenic exposure in mice also caused a significant change in serum biomarkers in the SGOT, SGPT and creatinine as compared to the controls. There were no significant changes in the serum levels of total protein in these mice. Co-administration of arsenic and fruit extract of amla (500 mg/kg body weight/day for 30 days) caused a significant reduction of arsenic transference associated with significantly decreases hepatic arsenic levels and balanced the antioxidant enzyme and levels of serum hepatic enzymes like SGOT and SGPT. The results of the present study clearly demonstrate the antioxidant property of amla that could be responsible for its protective efficacy in arsenic induced hepatic toxicity.",
Arsenic,1377919,"Inhibition Of DNA Repair As A Mechanism Of Arsenic Carcinogenesis Abstract: Arsenic is a metalloid that is widely distributed in the environment. Exposure to arsenic has been associated with an increased risk of a variety of cancers, including skin, liver, bladder, kidney and lung cancer. However attempts to prove arsenic carcinogenesis in animals have been unsuccessful. A hypothesis has been proposed that arsenic might act as a co-carcinogen instead of a carcinogen itself. Recently Rossman?s group demonstrated that arsenic enhanced the induction of skin tumors by UV irradiation in hairless Skh1 mice (Rossman, 2001). Consistent with its cocarcinogenic activity, arsenic by itself does not seem to induce point mutations in most of the bacteria and mammalian systems tesed. Instead, it can potentiate the mutagenicity of other mutagens, such as UV (Hartmann, 1996), Benzo(a)Pyrene (Maier, 2002) and N-methyl-N-nitrosourea (NMU)(Li, 1989). The mechanism of this co-mutagenicity remains unknown. The most tempting hypothesis is that arsenic can inhibit DNA repair. We have used arsenite at low concentrations in cultured human cells to test this hypothesis, in the hope of shedding light on the mechanism of arsenic mutagenesis and co-mutagenesis. Our study shows that (1) Arsenic at 1 uM is not mutagenic, but induces deletion/insertion mutations at 2.5 uM. Arsenic synergistically enhances UV mutagenicity at 2.5uM, but not at 1uM. (2) Arsenic treatment does not alter the UV mutation spectra. (3) Arsenic at 1-5 uM enhances and prolongs RPAp34 phosphorylation induced by UV irradiation, suggesting the persistence of the DNA damage signal that induces the phosphorylation response. This effect is less prominent in NER-deficient XPA cells. (4) Arsenic does not increase the generation of thymine dimers induced by UV assayed by FACS with thymine dimer-specific antibody, but it inhibits the removal of thymine dimers. All of these results suggest that arsenic inhibits DNA repair, probably nucleotide excision repair. Further work will be required to identify the mechanism of this inhibition.",
Arsenic,2149341,"Metals and Related Substances in drinking water: Proceedings of the 4th International Conference, METEAU Arsenic in drinking water and non-insulin-dependent diabetes in Zrenjanin Municipality, Serbia Abstract: ",
Arsenic,1508571,"Levels and chemical speciation of arsenic in representative biota and sediments of a tropical mangrove wetland, India Abstract: The general concern for arsenic in the marine environment is associated with its wide distribution and potential toxicity. In the present work, concentrations and chemical speciation of arsenic were characterized in sediments and representative biota from the Indian Sundarban, the largest continuous mangrove tract formed at the mouth of the Hugli (Ganges) River estuary, northeastern part of the Bay of Bengal. Analyzed organisms included both shellfish (Macoma birmanica, Sanguinolaria acuminata and Meretrix meretrix) and finfish (Liza parsia, Liza tade, Harpodon nehereus and Eleutheronema tetradactylum). Arsenic concentrations in sediments did not exceed 4 ?g g(-1) dry weight with the contribution of inorganic molecules (arsenate and arsenite) ranging from 61.7 to 81.3%. Total As (T(As)) concentrations varied from less than 2 to 16 ?g g(-1) in tissues of bivalves; the more elevated As accumulation was observed in gills and the mantle probably due to ion exchange properties of the mucous layer covering these organs, whereas adductor muscle and the podium showed limited values. Distribution of various arsenic compounds followed a quite similar trend in bivalve tissues; arsenobetaine (AsB) was the most dominant form followed by compounds such as dimethylarsinate (DMA), trimethyl arsine-oxide (TMAO), tetramethyl arsonium (TETRA) and arsenocholine (AsC), while inorganic arsenic (I(As)) represented a minor constituent (0.2 to 6.9%). Among the fish, detritivorous/herbivorous species (L. parsia and L. tade) exhibited T(As) concentrations of 10.8 and 9.71 ?g g(-1) dry wt with a prevalence of AsB (52-67%) and TETRA (26-35%); higher concentrations of T(As) were measured in the two carnivorous species (20.62 and 19.67 ?g g(-1) dry wt, in H. nehereus and E. tetradactylum respectively) mostly as AsB (63.3-72.3%) and AsC (17.5-28.6%). The obtained results can be considered as baseline levels for arsenic in the investigated area, confirming the predominance of organoarsenicals in marine organisms compared to more toxic inorganic compounds. Considering the ecological importance of this ecosystem and the increasing anthropogenic impact, the distribution of arsenic through the food chain should be continuously monitored, using organisms of different feeding guilds as indicators.",
Arsenic,2337226,"Urinary arsenic levels influenced by abandoned mine tailings in the Southernmost Baja California Peninsula, Mexico Abstract: Gold has been mined at San Antonio-El Triunfo, (Baja California Sur, Mexico) since the 18th century. This area has approximately 5,700 inhabitants living in the San Juan de Los Planes and El Carrizal hydrographic basins, close to more than 100 abandoned mining sites containing tailings contaminated with potentially toxic elements such as arsenic. To evaluate the arsenic exposure of humans living in the surrounding areas, urinary arsenic species, such as inorganic arsenic (iAs) and the metabolites mono-methylated (MMA) and di-methylated arsenic acids (DMA), were evaluated in 275 residents (18-84 years of age). Arsenic species in urine were analyzed by hydride generation-cryotrapping-atomic absorption spectrometry, which excludes the non-toxic forms of arsenic such as those found in seafood. Urinary samples contained a total arsenic concentration (sum of arsenical species) which ranged from 1.3 to 398.7 ng mL-1, indicating 33 % of the inhabitants exceeded the biological exposition index (BEI = 35 ng mL-1), the permissible limit for occupational exposure. The mean relative urinary arsenic species were 9, 11 and 80 % for iAs, MMA and DMA, respectively, in the Los Planes basin, and 17, 10 and 73 %, respectively, in the El Carrizal basin. These data indicated that environmental intervention is required to address potential health issues in this area.",
Arsenic,1016948,"Arsenite stimulates cyclooxygenase-2 expression through activating IkappaB kinase and nuclear factor kappaB in primary and ECV304 endothelial cells Abstract: Epidemiological studies have shown that chronic exposure to arsenic can result in liver injury, peripheral neuropathy, arteriosclerosis, and an increased incidence of cancer of the lung, skin, bladder, and liver. The overexpression of inducible cyclooxygenase-2 (Cox-2) has been associated with vascular inflammation and cellular proliferation. However, the effect of arsenite on Cox-2 gene expression in endothelial cells was left to be investigated. Western Blot analysis of HUVECs revealed a two-fold induction of Cox-2 protein by arsenite. This induction was associated with a two-fold increase of prostaglandin E2 in the media. Furthermore, the level of Cox-2 mRNA was correspondingly elevated as demonstrated by both Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses. Transfection of an immortalized human endothelium cell line (ECV304) with Cox-2 reporter gene constructs demonstrated that the transcription of Cox-2 gene was enhanced by arsenite. This induction was attenuated by pyrrolidine dithiocarbamate (PDTC), an inhibitor of NFkappaB. In addition, electrophoretic mobility shift assays indicated that NFkappaB activity was induced by arsenite. The kinase activity assay also indicated that IkappaB kinase (IKK) activity was induced by arsenite. These findings indicated that the induction of Cox-2 gene transcription by arsenite was through the stimulation of NFkappaB activity. Arsenite could induce IKK activity, which leads to the phosphorylation and degradation of IkappaB in ECV304 cells. Therefore, it appears that IKK signaling pathway is involved in arsenite-mediated Cox-2 expression.",
Arsenic,1798803,"Human urothelial micronucleus assay to assess genotoxic recovery by reduction of arsenic in drinking water: a cohort study in West Bengal, India Abstract: Chronic exposure to arsenic through drinking water affects nearly 26 million individuals in West Bengal, India. Cytogenetic biomarkers like urothelial micronucleus (MN) are extensively used to monitor arsenic exposed population. In 2004-2005, 145 arsenic exposed individuals and 60 unexposed controls were surveyed of which 128 exposed individuals and 54 unexposed controls could be followed up in 2010-2011. In 2004-2005, the extent of arsenic content in the drinking water was 348.23 ± 102.67 ?g/L, which was significantly lowered to 5.60 ± 10.83 ?g/L in 2010-2011. Comparing the data obtained between 2004-2005 and 2010-2011, there was a significant decline in the MN frequency, when assayed in 2010-2011 compared to 2004-2005. Hence, we infer that urothelial MN can be utilized as a good biomarker in detecting remedial effects from toxicity of the low dose of arsenic through drinking water.",
Arsenic,627825,"Manganese enhances peroxynitrite and leukotriene E4 formation in bovine aortic endothelial cells exposed to arsenic Abstract: Long-term exposure to arsenic in drinking water has been linked to cancer and other health effects, including cardiovascular disease. Arsenic in the environment is found in combination with a range of metals that could influence its toxicity. Manganese, in particular, is a metal that is typically found in conjunction with arsenic in contaminated groundwater. Peroxynitrite is a powerful oxidant formed from the reaction between nitric oxide and superoxide anion. Arsenic has been shown to increase the formation of peroxynitrite in bovine aortic endothelial cells (BAECs) and promote the formation of 3-nitrotyrosine (3-NY) in the atherosclerotic plaque of ApoE-/-/LDLr-/- mice. Arsenic exposure also increases leukotriene E4 (LTE4) formation in both the mice and BAECs, an effect that is partially reversed by the addition of Nomega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor. In the present study, we investigated the effect of adding nontoxic concentrations of manganese along with arsenic to BAEC cultures. Manganese increased arsenic toxicity and enhanced peroxynitrite, 3-NY, and LTE4 formation in BAECs. Addition of LNAME reduced 3-NY formation induced by arsenic/manganese mixtures, but in contrast to its effect on arsenic alone, L-NAME actually increased LTE4 synthesis in BAECs treated with the arsenic/manganese combination. Overall, these data suggest that manganese may exacerbate the toxic effects of arsenic on the vascular system.",
Arsenic,627188,"Functional and morphological effects of repeated sodium arsenite exposure on rat peripheral sensory nerves Abstract: Exposure to inorganic arsenic (iAs) is known to result in peripheral neuropathy. To better understand the functional and morphological consequences of iAs exposure, we examined the electrophysiological and histological characteristics of the sensory sural nerves in adult Male Wistar rats following 30 days of sodium arsenite administration by gavage (10 mg/kg body weight/day). Arsenic (As) levels in the peripheral nerves of exposed animals were about 150 times greater than those in controls. Lipid peroxidation was also increased in iAs-exposed animals. Compound action potentials (CAPs) evoked in iAs-exposed nerves were characterized by a slower conduction velocity ( approximately 26%). iAs-exposed nerves also showed a trend towards a decreased CAP area ( approximately 35%). These electrophysiological changes were consistent with histological alterations such as a approximately 56% decrease in myelin thickness. In addition, the perimeter and transverse area of axons were reduced to 29% and 45% of control, respectively. Our results suggest that accumulation of As produced by iAs exposure induces oxidative damage, severe demyelination, and other morphological alterations in axons of peripheral nerves. These changes may, in turn, induce changes in the generation and propagation of action potentials in peripheral nerves, leading to decreased transmission of information from peripheral sensory organs to the central nervous system.",
Arsenic,2278581,"Geochemistry and mineralogy of arsenic in mine wastes and stream sediments in a historic metal mining area in the UK Abstract: Mining generates large amounts of waste which may contain potentially toxic elements (PTE), which, if released into the wider environment, can cause air, water and soil pollution long after mining operations have ceased. The fate and toxicological impact of PTEs are determined by their partitioning and speciation and in this study, the concentrations and mineralogy of arsenic in mine wastes and stream sediments in a former metal mining area of the UK are investigated. Pseudo-total (aqua-regia extractable) arsenic concentrations in all samples from the mining area exceeded background and guideline values by 1-5 orders of magnitude, with a maximum concentration in mine wastes of 1.8×10(5)mgkg(-1) As and concentrations in stream sediments of up to 2.5×10(4)mgkg(-1) As, raising concerns over potential environmental impacts. Mineralogical analysis of the wastes and sediments was undertaken by scanning electron microscopy (SEM) and automated SEM-EDS based quantitative evaluation (QEMSCAN®). The main arsenic mineral in the mine waste was scorodite and this was significantly correlated with pseudo-total As concentrations and significantly inversely correlated with potentially mobile arsenic, as estimated from the sum of exchangeable, reducible and oxidisable arsenic fractions obtained from a sequential extraction procedure; these findings correspond with the low solubility of scorodite in acidic mine wastes. The work presented shows that the study area remains grossly polluted by historical mining and processing and illustrates the value of combining mineralogical data with acid and sequential extractions to increase our understanding of potential environmental threats.",
Arsenic,1351880,"Proteasome inhibitors induce heat shock response and increase IL-6 expression in human intestinal epithelial cells Abstract: In previous studies, the heat shock response, induced by hyperthermia or sodium arsenite, increased interleukin (IL)-6 production in intestinal mucosa and cultured human enterocytes. A novel way to induce the heat shock response, documented in other cell types, is treatment with proteasome inhibitors. It is not known if proteasome inhibition induces heat shock in enterocytes or influences IL-6 production. Here we tested the hypothesis that treatment of cultured Caco-2 cells, a human intestinal epithelial cell line, with proteasome inhibitors induces the heat shock response and stimulates IL-6 production. Treatment of Caco-2 cells with one of the proteasome inhibitors MG-132 or lactacystin activated the transcription factor heat shock factors (HSF)-1 and -2 and upregulated cellular levels of the 72-kDa heat shock protein HSP-72. The same treatment resulted in increased gene and protein expression of IL-6, a response that was blocked by quercetin. Additional experiments revealed that the IL-6 gene promoter contains a HSF-responsive element and that the IL-6 gene may be regulated by the heat shock response. The present results suggest that proteasome inhibition induces heat shock response and IL-6 production in enterocytes and that IL-6 may be a heat shock-responsive gene, at least under certain circumstances. The observations are important considering the multiple biological roles of IL-6, both locally in the gut mucosa and systemically, and considering recent proposals in the literature to use proteasome inhibitors in the clinical setting to induce the heat shock response.",
Arsenic,2278399,"Maternal fish and shellfish consumption and wheeze, eczema and food allergy at age two: A prospective cohort study in Brittany, France Abstract: Background: Environmental exposures, including dietary contaminants, may influence the developing immune system. This study assesses the association between maternal pre-parturition consumption of seafood and wheeze, eczema, and food allergy in preschool children. Fish and shellfish were studied separately as they differ according to their levels of omega-3 polyunsaturated fatty acids (which have anti-allergic properties) and their levels of contaminants. <br> <br>Methods: The PELAGIE cohort included 3421 women recruited at the beginning of pregnancy. Maternal fish and shellfish intake was measured at inclusion by a food frequency questionnaire. Wheeze, eczema, and food allergy were evaluated by a questionnaire completed by the mother when the child was 2 years old (n = 1500). Examination of the associations between seafood intake and outcomes took major confounders into account. Complementary sensitivity analyses with multiple imputation enabled us to handle missing data, due mostly to attrition. <br> <br>Results: Moderate maternal pre-parturition fish intake (1 to 4 times a month) was, at borderline significance, associated with a lower risk of wheeze (adjusted OR = 0.69 (0.45-1.05)) before age 2, compared with low intake (&lt;once/month). This result was not, however, consistent: after multiple imputation, the adjusted OR was 0.86 (0.63-1.17). Shellfish intake at least once a month was associated with a higher risk of food allergy before age 2 (adjusted OR = 1.62 (1.11-2.37)) compared to low or no intake (&lt;once/month). Multiple imputation confirmed this association (adjusted OR = 1.52 (1.05-2.21)). <br> <br>Conclusions: This study suggests that maternal pre-parturition shellfish consumption may increase the risk of food allergy. Further large-scale epidemiologic studies are needed to corroborate these results, identify the contaminants or components of shellfish responsible for the effects observed, determine the persistence of the associations seen at age 2, and investigate potential associations with health effects observable at later ages, such as allergic asthma.",
Arsenic,1021829,"Oxidative stress is implicated in arsenic-induced neural tube defects in chick embryos Abstract: The potential of arsenic to induce neural tube defects (NTDs) remains a topic of controversy. In our previous study, oxidative stress and altered DNA methylation were observed in arsenic-exposed animal models. However, the correlation between these conditions was not fully understood. Therefore, our present aim was to determine whether arsenic exposure results in altered reactive oxygen species levels that affect DNA methylation and may contribute to NTDs in chick embryos. We demonstrated that arsenic-induced NTDs were associated with oxidative stress. Increased intracellular oxidative species and DNA methylation changes were observed following arsenic exposure. These changes were accompanied by a decrease in manganese superoxide dismutase activity. Furthermore, a significant decrease in DNA methyltransferase (DNMT) 1 and 3a expression was observed following arsenic exposure. The known antioxidant N-acetyl-l-cysteine, a known antioxidant, ameliorated global DNA hypomethylation and the decreased DNMT 1 and 3a expression observed during arsenic exposure. In addition, arsenic caused a significant decrease in S-adenosylmethionine (SAM) and significant increase in S-adenosylhomocysteine (SAH). This effect resulted in a significant reduction of the SAM/SAH ratio, which may also contribute to DNA hypomethylation. In conclusion, oxidative stress and reduction in SAM/SAH ratio during arsenic exposure in chick embryos seem to modulate DNA methylation and contribute to arsenic-induced NTDs via epigenetic mechanisms.",
Arsenic,1070382,"Differential modulation of aryl hydrocarbon receptor regulated enzymes by arsenite in the kidney, lung, and heart of C57BL/6 mice Abstract: During the last couple of decades, efforts have been made to study the toxic effects of individual aryl hydrocarbon receptors (AhR) ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or heavy metals typified by arsenic As(III). However, little is known about the combined toxic effects of TCDD and As(III) in vivo. Previous reports from our laboratory and others have demonstrated that As(III), by itself or in the presence of AhR ligands, such as TCDD, is capable of differentially altering the expression of various phase I and phase II AhR-regulated genes in in vitro systems. Thus, the objective of the current study was to investigate whether or not similar effects would occur at the in vivo level. Therefore, we examined the effect of exposure to As(III) (12.5 mg/kg) in the absence and presence of TCDD (15 ?g/kg) on the AhR-regulated genes using C57Bl/6 mice. Our results demonstrated that As(III) alone inhibited Cyp1a1 and Cyp1a2 in the kidney, while it induced their levels in the lung and did not affect their mRNA levels in the heart. As(III) also induced Nqo1 and Gsta1 in all tested tissues. Upon co-exposure to As(III) and TCDD, As(III) inhibited the TCDD-mediated induction of Cyp1a1 in the kidney and heart, Cyp1a2 in the kidney and heart, while it potentiated TCDD-mediated induction of Cyp1a1 in the lung, and Nqo1 and Gsta1 in the kidney and lung. In conclusion, the present study demonstrates for the first time that As(III) modulates constitutive and TCDD-induced AhR-regulated genes in a time-, tissue-, and AhR-regulated enzyme-specific manner.",
Arsenic,1341055,"Differential cytotoxic effects of sodium meta-arsenite on human cancer cells, dental papilla stem cells and somatic cells correlate with telomeric properties and gene expression Abstract: We investigated the effects of sodium meta-arsenite (NaAsO(2)) on human cancer cells (MDA-MB-231, MCF-7 and U-87 MG), dental papilla tissue stem cells (DPSCs) and somatic cells [MRC-5 fetal fibroblasts and adult muscle cells (MCs)] by examining telomeric properties, endogenous reverse transcriptase (RT) activity and the expression of tumorigenesis-linked genes. Half maximal inhibitory concentration (IC(50)) values were higher in DPSCs and MCs, possessing longer telomere lengths when compared to cancer cells. Levels of telomerase and RT activity, and the expression of protein 53 (p53), B-cell lymphoma 2 (BCL2), nuclear factor kappa-light-chain-enhancer of activated B-cells (NF?B), transforming growth factor beta (TGF?) and vascular endothelial growth factor (VEGF) were significantly lower in cancer cells following sodium meta-arsenite treatment, whereas the effect was absent or marginally detected in DPSCs and somatic cells. Collectively, sodium meta-arsenite effectively induced cellular cytotoxicity by inhibiting telomerase and RT activity, and down-regulating transcript levels in cancer cells with shorter telomere lengths, whereas more tolerance was evident in DPSCs and somatic cells possessing longer telomere lengths.",
Arsenic,2149259,"Isolation and molecular characterization of arsenite-tolerant Alishewanella sp. GIDC-5 originated from industrial effluents Abstract: An As-hypertolerant Alishewanella sp. GIDC-5 (Accession no. HQ659190) was isolated from an effluent treatment plant of the industrial area near Sachin, Gujarat (India). In vitro studies revealed that GIDC-5 can tolerate 18mM of arsenite [As(III)] and 220mM of arsenate [As(V)]. PCR analysis confirmed the presence of arsenite transporters [arsB and ACR3(1)] and arsenite oxidase gene [aioB]. Specific activities of arsenite oxidase and arsenate reductase, located on membrane and cytoplasmic fractions respectively, increased in dose dependent manner with arsenite concentration. Also, specific activities of antioxidant enzymes viz., catalase, ascorbate peroxidase, superoxide dismutase and glutathione S-transferase increased in presence of arsenite. Increased exposure to arsenite changes enzyme activities of the glycolysis, Krebs and glyoxylate branches dramatically. These results reveal that along with ars operon, metabolic adaptation and antioxidant activities participate in As(III) tolerance in Alishewanella sp. GIDC-5.",
Arsenic,1023983,"Treating and drinking well water in the presence of health risks from arsenic contamination: results from a U.S. hot spot Abstract: The Safe Drinking Water Act of 1974 regulates water quality in public drinking water supply systems but does not pertain to private domestic wells, often found in rural areas throughout the country. The recent decision to tighten the drinking water standard for arsenic from 50 parts per billion (ppb) to 10 ppb may therefore affect some households in rural communities, but may not directly reduce health risks for those on private wells. The article reports results from a survey conducted in a U.S. arsenic hot spot, the rural area of Churchill County, Nevada. This area has elevated levels of arsenic in groundwater. We find that a significant proportion of households on private wells are consuming drinking water with arsenic levels that pose a health risk. The decision to treat tap water for those on private wells in this area is modeled, and the predicted probability of treatment is used to help explain drinking water consumption. This probability represents behaviors relating to the household's perception of risk.",
Arsenic,627018,"Environmental arsenic exposure and sputum metalloproteinase concentrations Abstract: Exposure to arsenic in drinking water is associated with an increased rate of lung cancer. The objective of this study was to determine whether arsenic exposure at relatively low concentrations (approximately 20 microg/L) is associated with changes in biomarkers of lung inflammation, as measured by the ratio of sputum metalloproteinase and antiproteinase activity. A total of 73 subjects residing in Ajo and Tucson, Arizona were recruited for this cross-sectional study. Tap water and first morning void urine were analyzed for arsenic. Matrix metalloproteinase 2 (MMP-2), 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) were measured in induced sputum. Household tap water arsenic levels in Ajo (20.3+/-3.7 microg/L) were higher than in those Tucson (4.0+/-2.3 microg/L), as were mean urinary total inorganic arsenic levels (29.1+/-20.4 and 11.0+/-12.0 microg/L, respectively). Log-normalized MMP-2, MMP-9, and TIMP-1 concentrations in sputum were not significantly different between towns. However, after adjusting for town, asthma, diabetes, urinary monomethylarsonic acid/inorganic arsenic, and smoking history, total urinary arsenic was negatively associated with MMP-2 and TIMP-1 levels in sputum and positively associated with the ratio of MMP-2/TIMP-1 and MMP-9/TIMP-1 in sputum. Increased sputum proteinase/antiproteinase activity suggests a potential toxic mechanism for low-level arsenic exposure.",
Arsenic,1337695,"Arsenic speciation in Chinese herbal medicines and human health implication for inorganic arsenic Abstract: Rice and drinking water are recognized as the dominant sources of arsenic (As) for human intake, while little is known about As accumulation and speciation in Chinese Herbal Medicines (CHMs), which have been available for many hundreds of years for the treatment of diseases in both eastern and western cultures. Inorganic arsenic was the predominant species in all of CHMs samples. The levels of inorganic arsenic in CHMs from fields and markets or pharmacies ranged from 63 to 550 ng/g with a mean of 208 ng/g and 94 to 8683 ng/g with a mean of 1092 ng/g, respectively. The highest concentration was found in the Chrysanthemum from pharmacies. It indicates that the risk of inorganic As in CHMs to human health is higher in medicines from markets or pharmacies than that collected directly from fields. Some CHMs may make a considerable contribution to the human intake of inorganic arsenic.",
Arsenic,627352,"DNA repair gene XPD and susceptibility to arsenic-induced hyperkeratosis Abstract: Chronic exposure to inorganic arsenic is known to cause non-melanocytic skin and internal cancers in humans. An estimated 50-70 million people in Bangladesh have been chronically exposed to arsenic from drinking water and are at risk of skin and other cancers. We undertook the first study to examine whether genetic susceptibility, as determined by the codon 751 SNP (A-->C) of the DNA repair gene XPD, influences the risk of arsenic-induced hyperkeratotic skin lesions, precursors of skin cancer, in a case-control study of 29 hyperkeratosis cases and 105 healthy controls from the same community in an area of Bangladesh. As expected, there was a monotonic increase in risk of hyperkeratosis in relation to urinary arsenic measures but the XPD genotype was not independently associated with the risk. However, the increase in hyperkeratosis risk in relation to urinary arsenic measures genotype was borderline significant for urinary total arsenic (P for trend=0.06) and statistically significant for urinary creatinine adjusted arsenic (P for trend=0.01) among subjects with the XPD A allele (AA) but not among subjects with the other XPD genotypes. Among AA carriers, the risk for the highest arsenic exposed group compared with the lowest was more than 7-fold for urinary total arsenic and about 11-fold for urinary creatinine adjusted arsenic. In conclusion, our findings suggest that the DNA repair gene XPD may influence the risk of arsenic-induced premalignant hyperkeratotic skin lesions. Future larger studies are needed to confirm this novel finding and investigate how combinations of different candidate genes and/or other host and environmental factors may influence the risk of arsenic induced skin and other cancers.",
Arsenic,1381353,"Effect of PAO (phenylarsine oxide) on the inhibitory effect of insulin and IGF-1 on insulin release from INS-1 cells Abstract: Phenylarsine oxide (PAO) which complexes vicinal thiol groups is a valuable pharmacological tool to investigate the interaction of peptides such as insulin with their receptors and the signal transduction from the receptor to the cell interior. This tool was now used to elucidate the inhibitory effects of insulin and IGF-1 on insulin secretion via their receptors. Insulin and IGF-1 inhibited insulin release from INS-1 cells, an insulin secreting cell line. PAO was able to reverse this inhibitory effect of both hormones. Dimercaptopropanol (DMP), which is well known to antagonize PAO effects, inhibited the abolishment of PAO effect on the inhibitory effect of insulin and IGF-1 regarding insulin release. Membrane bound GLUT2 in INS-1 cells was increased by either insulin and IGF-1 which is counteracted by PAO. Thus the inhibitory effect of insulin and IGF-1 on insulin release is operative and can be disturbed by a thiol interacting compound such as PAO. This may happen at the receptor level or at the sub-receptor level.",
Arsenic,631702,"Comparison of gene expression profiles in HepG2 cells exposed to arsenic, cadmium, nickel, and three model carcinogens for investigating the mechanisms of metal carcinogenesis Abstract: Carcinogenesis is an important chronic toxicity of metals and metalloids, although their mechanisms of action are still unclear. Comparison of gene expression patterns induced by carcinogenic metals, metalloids, and model carcinogens would give an insight into understanding of their carcinogenic mechanisms. In this study, we examined the gene expression alteration in human hepatoma cell line, HepG2, after exposing to two metals (cadmium and nickel), a metalloid (arsenic), and three model carcinogenic chemicals N-dimethylnitrosoamine (DMN), 12-O-tetradecanoylphorbol-13-acetate (TPA), and tetrachloroethylene (TCE) using DNA microarrays with 8,795 human genes. Of the genes altered by As, Cd, and Ni exposures, 31-55% were overlapped with those altered by three model carcinogenic chemical exposures in our experiments. In particular, the metals and metalloid shared certain characteristics with TPA and TCE in remarkable upregulations of the genes associated with progression of cell cycle, which might play a central role in As, Cd, and Ni carcinogenesis. This characteristic of gene expression alteration was partially counteracted by intracellular accumulation of vitamin C in As-exposed cells, whereas the number of cell-cycle associated genes was increased in Cd- and Ni-exposed cells. In our experimental conditions, ROS might have an accelerative effect on the cell proliferation mechanisms of As, but have an inhibitory effect on those of other two heavy metals. Furthermore, based on the results of Q-PCR, the oncogene PTTG1, which was upregulated by all carcinogenic chemical exposures in the array experiments, might be a useful biomarker for evaluation of the carcinogenesis of inorganic carcinogens",
Arsenic,626996,"Evidence of an immunologic mechanism behind the therapeutical effects of arsenic trioxide (As(2)O(3)) on myeloma cells Abstract: Exposure of RPMI 8226, Karpas 707 and U266 human myeloma-like lines to low doses of As(2)O(3) was followed by a marked increase in lymphokine activated killers (LAK)-mediated killing and up- modulation of CD38 and CD54, two molecules involved in cell-cell interactions. Moreover, simultaneous exposure of effectors and targets to As(2)O(3) yielded the most effective condition for lysis. The expression of CD31 (CD38 ligand) and CD11a (CD54 ligand) was also up-regulated by LAK, suggesting that increased adhesion was responsible for the improved killing. Similar results were obtained using freshly isolated myeloma cells. These findings indicate that As(2)O(3) may be useful to boost the immune system against myelomas.",
Arsenic,1508545,"Treatment of organic matter and methylated arsenic in landfill biogas condensate Abstract: To explore the feasible treatment alternatives for organic contaminant, especially organic arsenic species in the landfill gas (LFG) condensate, a variety of treatment approaches were examined and evaluated in this study. Biological degradation, conventional and advanced oxidation, and physical absorption showed limited effectiveness to convert the methylated arsenic to inorganic arsenic. Reverse osmosis (RO) was found to be able to remove the organic arsenic and meet the discharge limits. Maximum removal efficiency and cost level were summarized for all treatment approaches tested, which can be a reference for the organic arsenic treatment method selection under different circumstances.",
Arsenic,628812,"Effects of dimethylsulphoxide on mice arsenite-induced dysmorphogenesis in embryo culture and cytotoxicity in embryo cells Abstract: Dimethylsulphoxide (DMSO) is a widely used vehicle for water insoluble compounds in experimental studies. Nevertheless, little is known about its potential impact on dysmorphogenesis caused by reactive oxygen species (ROS). In order to evaluate if DMSO at concentrations used as vehicle can alter in vitro sodium arsenite (Asi) teratogenicity and cytotoxicity, mouse embryos with 4-5 somites were grown for 48 h in Asi 0.4 and 4 microM, with and without 0.1% DMSO (v/v). Also embryonic mesenchymal cell were cultured, using mesenchymal mouse embryo cells obtained from gestation day 11 and treated with DMSO 0.1%, 0.2% and 0.5% (v/v) 15 min before Asi was added at final concentrations of 0.4 and 4 microM. Cytotoxicity and intracellular ROS production, were evaluated with MTT and 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA), respectively. Results indicated that Asi produced growth retardation and abnormal development. Main malformations involved neural tube closure defects, abnormal rotation and optic vesicle defects among others. Co-treatment with DMSO partially reduced neural tube defects as well as facial dysmophology. Asi reduced cell viability inversely to the level of ROS production, and DMSO returned cellular viability to control values by reducing ROS intracellular production. In summary, the protective effect observed for DMSO appeared to reflect free radical scavenger properties, though other mechanisms independent to ROS production may have also been involved.",
Arsenic,952909,"Inhibition of poly(ADP-ribose) polymerase-1 by arsenite interferes with repair of oxidative DNA damage Abstract: Arsenic enhances skin tumor formation when combined with other carcinogens, including UV radiation (UVR). In this study we report that low micromolar concentrations of arsenite synergistically increases UVR-induced oxidative DNA damage in human keratinocytes as detected by 8-hydroxyl-2'-deoxyguanine (8-OHdG) formation. Poly(ADP-ribose) polymerase-1 (PARP-1) is involved in base excision repair, a process that repairs 8-OHdG lesions. Arsenite suppresses UVR-induced PARP-1 activation in a concentration-dependent manner. Inhibition of PARP-1 activity by 3-aminobenzamide or small interfering RNA silencing of PARP-1 expression significantly increases UVR-induced 8-OHdG formation, suggesting that inhibition of PARP-1 activity by arsenite contributes to oxidative DNA damage. PARP-1 is a zinc finger protein, and mass spectrometry analysis reveals that arsenite can occupy a synthetic apopeptide representing the first zinc finger of PARP-1 (PARPzf). When the PARPzf peptide is preincubated with Zn(II) followed by incubation with increasing concentrations of arsenite, the ZnPARPzf signal is decreased while the AsPARPzf signal intensity is increased as a function of arsenite dose, suggesting a competition between zinc and arsenite for the same binding site. Addition of Zn(II) abolished arsenite enhancement of UVR-stimulated 8-OHdG generation and restored PARP-1 activity. Our findings demonstrate that arsenite inhibits oxidative DNA damage repair and suggest that interaction of arsenite with the PARP-1 zinc finger domain contributes to the inhibition of PARP-1 activity by arsenite. Arsenite inhibition of poly(ADP-ribosyl)ation is one likely mechanism for the reported co-carcinogenic activities of arsenic in UVR-induced skin carcinogenesis.",
Arsenic,1029262,"A pilot simulation study of arsenic tracked from CCA-treated decks onto carpets Abstract: A controlled simulation experiment was performed to assess whether dislodgeable arsenic can be tracked onto carpets via foot traffic from chromated copper arsenate (CCA) pressure-treated decks. The pilot simulation study demonstrated that it is possible to track arsenic from CCA-decks onto carpets under the test conditions evaluated. A total of nine CCA-decks and two non-CCA-treated control surfaces were tested under wet and dry conditions. Five participants walked in a controlled manner (60 cycles, 11 steps per cycle) across decks and then walked over various lanes of carpet to simulate the tracking of arsenic indoors on the bottoms of shoes under heavy foot traffic conditions. To determine if arsenic was transferred from the CCA-treated wood to the carpet via shoes, laboratory analysis was performed on three different types of samples: (1) wipe samples of dislodgeable arsenic from a 46 cm(2) area of carpet, (2) dust samples obtained from vacuuming a 7442 cm(2) area of carpet, and (3) extractions of 13 cm(2) carpet samples. Wipe samples were also taken directly from the deck lumber. Following digestion and extraction, the amount of arsenic in each sample was measured using Graphite Furnace Atomic Absorption Spectrometry. The mean arsenic concentration measured on the carpets was 2.52 microg/(100 cm(2)) and 2.05 microg/(100 cm(2)) with wipes for the dry and wet conditions, respectively, 4.69 microg/(100 cm(2)) and 0.68 microg/(100 cm(2)) with vacuumed dust for the dry and wet conditions, respectively, and 15.56 microg/(100 cm(2)) and 12.31 microg/(100 cm(2)) with carpet extractions for the dry and wet conditions, respectively. The mean arsenic concentration measured on the decks was 22.2 microg/(100 cm(2)) with wipes. Further research is needed to determine if indoor exposure to arsenic due to track-in from outdoor decks via foot traffic is significant compared to exposures from other sources.",
Arsenic,1353495,"Arsenite induces p70S6K1 activation and HIF-1 alpha expression in prostate cancer cells Abstract: Arsenite is ubiquitous in the environment, particularly in the form of contaminated water. Although this metal is a known human carcinogen, its exact mechanism of action remains unclear. P70S6K1 phosphorylates the ribosomal 40S protein leading to increased protein translation, and is an important regulator of cell growth and proliferation. Hypoxia inducible factor-1 (HIF-1) is a basic helix-loop-helix transcription factor composed of two subunits, HIF-1alpha and HIF-1beta. HIF-1 activates the transcription of a number of genes that mediate angiogenesis and tumor formation. In this study we demonstrated that arsenite treatment increased levels of p70S6K1 phosphorylation and p70S6K1 activity in a PI3K and mTOR sensitive manner. We have also shown that arsenite specifically induces HIF-1alpha, but not HIF-1beta, protein levels in prostate cancer cells in a mTOR-dependent manner.",
Arsenic,1797758,"N-(2-Carboxybenzyl) grafted chitosan as adsorptive agent for simultaneous removal of positively and negatively charged toxic metal ions Abstract: A chitosan material, cross-linked and grafted with N-(2-carboxybenzyl) groups, was evaluated as adsorbent to sufficiently remove both positively charged ions (Cu(II), Ni(II)) and negatively charged ones (Cr(VI), As(V)) from aqueous solutions. After complete characterization study with FTIR, SEM and BET analysis, the evaluation of adsorption was done with experiments at pH range 2-12 and then varying the initial concentrations of ions. Langmuir-Freundlich equation was used to fit the adsorption data and showed maximum adsorption capacities 308 mg/g at 25 °C for copper and 381 mg/g for nickel ions. The adsorption capacity of As(V) was 208 mg/g and 175 mg/g for Cr(VI). Also, a mechanistic (phenomenological) model of adsorption kinetics is employed to fit the kinetic data found using parameters with physical meaning, and clearly understand the process dynamics. The regeneration of adsorbents was presented in ten cycles of reuse (adsorption-desorption), showing the strong reuse potential of the adsorbent used.",
Arsenic,498592,"Mortality patterns among workers exposed to arsenic, cadmium, and other substances in a copper smelter Abstract: Objective To evaluate the long-term mortality experience of workers exposed to arsenic, cadmium, and other substances at a copper mine and smelter in Copperhill, Tennessee studied earlier as part of an industry-wide stud) Methods Subjects were 2,422 male workers employed three or more years in the smelter or mill between 1/1/46 until the plant strike and scale-down of operations in April 1996. Vital status was determined through 2000 for 99.4% of subjects and cause of death for 91.3% of 878 deaths. Historical exposures were estimated for lead, SO2, arsenic, cadmium, dust, and cobalt. We computed standardized mortality, ratios (SMRs) based oil U.S. and local county rates and modeled internal relative risks (RRs). Results We observed overall deficits in deaths based on national and local county comparisons from all causes, all cancers and most of the cause of death categories examined. We found limited evidence of increasing mortality, risks from cerebrovascular disease with increasing duration and cumulative arsenic exposure, but no evidence of an exposure-response relationship for cadmium exposure and bronchitis. Conclusions Our limited evidence of an association between inhaled arsenic exposure and CVD is an exploratory finding not observed in other epidemiology studies of more highly exposed occupational populations. Possible alternative explanations include chance alone and uncontrolled confounding or effect modification by co-exposures or other factors correlated with arsenic exposure and unique to the Copperhill facility. Am. J. Ind. Med. 52:633-644, 2009. (C) 2009 Wiley-Liss, Inc.",
Arsenic,568984,"Further evidence against a direct genotoxic mode of action for arsenic-induced cancer Abstract: Arsenic in drinking water, a mixture of arsenite and arsenate, is associated with increased skin and other cancers in Asia and Latin America, but not the United States. Arsenite alone in drinking water does not cause skin cancers in experimental animals; therefore, it is not a complete carcinogen in skin. We recently showed that low concentrations of arsenite enhanced the tumorigenicity of solar UV irradiation in hairless mice, suggesting arsenic cocarcinogenesis with sunlight in skin cancer and perhaps with different carcinogenic partners for lung and bladder tumors. Cocarcinogenic mechanisms could include blocking DNA repair, stimulating angiogenesis, altering DNA methylation patterns, dysregulating cell cycle control, induction of aneuploidy and blocking apoptosis. Arsenicals are documented clastogens but not strong mutagens, with weak mutagenic activity reported at highly toxic concentrations of inorganic arsenic. Previously, we showed that arsenite, but not monomethylarsonous acid (MMA[III]), induced delayed mutagenesis in HOS cells. Here, we report new data on the mutagenicity of the trivalent methylated arsenic metabolites MMA(III) and dimethylarsinous acid [DMA(III)] at the gpt locus in Chinese hamster G12 cells. Both methylated arsenicals seemed mutagenic with apparent sublinear dose responses. However, significant mutagenesis occurred only at highly toxic concentrations of MMA(III). Most mutants induced by MMA(III) and DMA(III) exhibited transgene deletions. Some non-deletion mutants exhibited altered DNA methylation. A critical discussion of cell survival leads us to conclude that clastogenesis occurs primarily at highly cytotoxic arsenic concentrations, casting further doubt as to whether a genotoxic mode of action (MOA) for arsenicals is supportable.",
Arsenic,744882,"The role of the RAS signaling pathway in androgen-independence acquired during arsenic-induced malignant transformation of human prostate epithelial cells Abstract: In humans progression of prostate cancer to androgen-independence (AI) signals a marked worsening of prognosis, and is linked to autocrine or paracrine growth. Evidence indicates that the androgen receptor (AR) and Ras can be involved in acquired AI in prostate cancer. Inorganic arsenic is a potential human prostate carcinogen but its role in prostate tumor progression is undefined. Thus, we studied AI in CAsE-PE cells, a malignant transformant of the non-tumorigenic human prostate epithelial cell line RWPE-1 induced by chronic arsenic exposure. The transformant grew at a much faster rate in complete medium than control cells and also showed sustained growth in steroid-reduced medium. Although similar levels of AR occurred in control and CAsE-PE cells, androgens were less effective in stimulating cell proliferation and AR-related gene expression in CAsE-PE cells. For instance, dihydrotestosterone increased PSA transcript much more in control (4.5- fold) than CAsE-PE (1.5-fold) cells. CAsE-PE cells also showed relatively low levels of growth stimulation by non-androgen steroids, such as estradiol. These data indicate that arsenic did not induce AR over-expression or loss of AR ligand specificity, both of which can occur with acquired AI in prostate cancer. CAsE-PE cells did, however, display constitutively increased expression of unmutated K-Ras (13-fold). Ras is a common component of many signaling pathways activated in advanced prostate cancer. Indeed, events downstream of K-Ras, including A-Raf and B-Raf (both serine-threonine MAP kinases) showed increased constitutive expression in CAsE-PE cells (2.2-fold and 3.2-fold, respectively) compared to control. Thus, arsenic induced malignant transformation is associated with acquired AI in human prostate cells and Ras activation and up-regulation of down-stream pathways appear to correlate with this tumor progression.",
Arsenic,1348325,"15-Deoxy-Delta(12,14)-prostaglandin J(2) facilitates thyroglobulin production by cultured human thyrocytes Abstract: A cyclopentenone-type prostaglandin, 15-deoxy-Delta(12, 14)-prostaglandin J(2) (15-d-PGJ(2)), has been shown to induce the cellular stress response and to be a ligand for the peroxisome proliferator-activated receptor (PPAR)-gamma. We studied its effect on the basal and thyrotropin (TSH)-induced production of thyroglobulin (TG) by human thyrocytes cultured in the presence of 10% FBS. In 15-d-PGJ(2)-treated cells in which the agent itself did not stimulate cAMP production, both the basal production of TG and the response to TSH were facilitated, including the production of TG and cAMP, whereas such production was decreased in untreated cells according to duration of culture. PGD(2) and PGJ(2), which are precursors to 15-d-PGJ(2), exhibited an effect similar to 15-d-PGJ(2). However, the antidiabetic thiazolidinediones known to be specific ligands for PPAR-gamma, and WY-14643, a specific PPAR-alpha ligand, lacked this effect. 15-d-PGJ(2) and its precursors, but not the thiazolidinediones, induced gene expression for heme oxygenase-1 (HO-1), a stress-related protein, and strongly inhibited interleukin-1 (IL-1)-induced nitric oxide (NO) production. Cyclopentenone-type PGs have been recently shown to inhibit nuclear factor-kappaB (NF-kappaB) activation via a direct and PPAR-independent inhibition of inhibitor-kappaB kinase, suggesting that, in human thyrocytes, such PGs may inhibit IL-1-induced NO production, possibly via an inhibition of NF-kappaB activation. On the other hand, sodium arsenite, a known activator of the stress response pathway, induced HO-1 mRNA expression but lacked a promoting effect on TG production. Thus 15-d-PGJ(2) and its precursors appear to facilitate TG production via a PPAR-independent mechanism and through a different pathway from the cellular stress response that is available to cyclopentenone-type PGs. Our findings reveal a novel role of these PGs associated with thyrocyte differentiation.",
Arsenic,1509331,"Effects of soil components and liming effect of CCA-wood ash upon leaching of Cu, Cr, and As from CCA-wood ash in Ultisol soil Abstract: The burning of wood that has been chemically treated with chromated copper arsenate (CCA) produces an ash containing high concentrations of copper, chromium, and arsenic (CCA-metals). The rainwater-leaching of these metals from burn sites can produce increased soil and water contamination. Soil systems have varying natural abilities to retard leaching and they also impact metals speciation and toxicity through sorption, conversion, and sedimentation-related mechanisms. Recent regulations restricting the use of CCA-treatment have resulted in increased quantities of CCA-treated lumber entering the waste stream, making studies of metals leaching from CCA-wood ash and soil/CCA-wood ash systems important areas of investigation. Wood ash composition, soil composition, and CCA-metals speciation are all important factors determining the degree of the metal mobility in a soil system containing metals leached from CCA-wood ash. The CCA-metals composition of CCA-wood ash was determined by analytical methods. Both pH and batch leaching studies were used to postulate mobility mechanisms within the CCA-wood ash/soil system. The contrasting effects of untreated-wood ash and CCA-wood ash on soil components are presented in order to assess the potential for enhancement of immobilization mechanisms that increase the soil system retardance of CCA-metals mobility. Results of this investigation show that the Ultisol test soil retards the mobility of As and Cr compared to CCA-wood ash alone, while Cu mobility is increased in the presence of the Ultisol test soil. Experimental results show that the alkalinity of a CCA-wood ash/Ultisol soil system is lower than that of an untreated-wood ash/Ultisol soil system. This indicates a difference in chemical composition and the potential consumption of hydroxyl ions during treatment by the retardance mechanisms affecting Cr and As mobility. Therefore, the study of these contaminated soil systems and the potential enhancement of immobilization mechanisms are important areas of investigation.",
Arsenic,1019545,"Sodium arsenite reduces proliferation of human activated T-cells by inhibition of the secretion of interleukin-2 Abstract: Arsenic (As) is a common metalloid which contaminates drinking water in several regions of the world and chronic exposure is associated with skin, lung, bladder, and kidney cancer. Previous studies suggest that arsenic exposure leads to a diminution of phytohemaglutinin (PHA) stimulated T cell proliferation in humans. In order to understand the mechanism of this suppression, the effect of As was evaluated on the expression of CD25, and IL-2 secretion in human peripheral blood mononuclear cells (PBMC). Inhibition of proliferation was observed in all donors studied. Most of the donors did not show any change in the expression of CD25, but IL-2 secretion was inhibited in 6 of the 7 donors tested. Proliferative inhibition was due to a suboptimal levels of IL-2 secreted by lymphocytes, since the addition of recombinant IL-2 to the cultures reversed in a dose-dependent fashion the inhibitory effect of As. The determination of the mRNA of IL-2 and the intracellular IL-2 levels demonstrated that the inhibition is not at the transcriptional level. Electron microscopy studies revealed that cellular ultrastructure in Golgi apparatus, mitochondria, cytoskeleton, and perinuclear membrane were altered. These alterations suggest that due to sodium arsenite effects on cytoskeleton, the intracellular secretion of proteins is affected, including the one of IL-2, leading to an impaired proliferation of the T cells when stimulated with PHA.",
Arsenic,1704147,Influence of Arsenate on Lipid Peroxidation Levels and Antioxidant Enzyme Activities in Bacillus cereus Strain XZM002 Isolated from High Arsenic Aquifer Sediments Abstract: ,
Arsenic,1341356,"Involvement of c-Met- and phosphatidylinositol 3-kinase dependent pathways in arsenite-induced downregulation of catalase in hepatoma cells Abstract: Catalase protects cells from reactive oxygen species-induced damage by catalyzing the breakdown of hydrogen peroxide to oxygen and water. Arsenite decreases catalase activity; it activates phosphatidylinositol 3-kinase (PI3K) and its key downstream effector Akt in a variety of cells. The PI3K pathway is known to inhibit catalase expression. c-Met, an upstream regulator of PI3K and Akt, is also involved in the regulation of catalase expression. To examine the involvement of c-Met and PI3K pathways in the arsenite-induced downregulation of catalase, catalase mRNA and protein expression were analyzed in the human hepatoma cell line HepG2 treated with arsenite and either an inhibitor of c-Met (PHA665752 (PHA)) or of PI3K (LY294002 (LY)). Arsenite treatment markedly activated Akt and decreased the levels of both catalase mRNA and protein. Both PHA and LY attenuated arsenite-induced activation of Akt. PHA and LY treatment also prevented the inhibitory effect of arsenite on catalase protein expression but did not affect the level of catalase mRNA. These findings suggest that arsenite-induced inhibition of catalase expression is regulated at the mRNA and post-transcriptional levels in HepG2 cells, and that the post-transcriptional regulation is mediated via c-Met- and PI3K-dependent mechanisms.",
Arsenic,2345833,"Effects of organic/inorganic amendments on trace elements dispersion by leachates from sulfide-containing tailings of the Sao Domingos mine, Portugal. Time evaluation Abstract: Greenhouse pot experiments were conducted over 13 months to evaluate the effect of two amendment mixture doses (30 and 75 Mg/ha) on the geochemical dispersion of trace elements by leaching hazardous mine wastes from the Sao Domingos mine. Mineralogical evolution of these materials was also evaluated. Amendment mixtures containing solid wastes from agriculture (plant remains + strawberry substrate and rocicwool used for the strawberry crop) and from distillation of Ceratonia siliqua Land Arbutus unedo L fruits were used to improve the chemical characteristics of leachates from sulfide mine wastes. Sulfide mine wastes had acidic characteristics, as well as high electrical conductivity and total element concentrations (g/kg; AI: 54.8-612; Fe: 104.0-110.0; Pb: 9.0-13.8; S: 63.6-68.0; As: approximate to 1). These features contributed to the large capacity for leaching of hazardous elements during, at least, the first four months of incubation. In the seventh month of incubation, there was a significant decrease in the leachate concentration of the majority of hazardous elements. The addition of amendments minimised trace element dispersion in leachate percolation during the first seven months (25 to 99% reduction compared to control, depending on the element and sampling period). However, the leachate characteristics were not influenced by amendment doses and no significant differences were observed in leachate composition (control and amended treatments) after 13 months. Amendment application led to differences between the solid phases of the efflorescent salts formed on the surface of the control and the amended treatments. The efflorescent salts contained very soluble aluminium sulfates, together with alunite-jarosite-group solid phases in amended samples, and copiapite-group solid phases in control. In the core materials (5 to 10 cm in depth), the mineralogy was similar in both control and amended samples. The presence of various stable solid phases from alunite-jarosite-group, such as jarosite and beudantite (mainly in deeper materials), can explain the low concentrations of trace elements in the leachates after thirteen months. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,2279127,"Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings Abstract: Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p < 0.05), whose primary source in indoor air is resuspended soil from outdoors. In the second rural community, our estimated metal concentrations in air were comparable to active air sampling measurements taken previously. This passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites.",
Arsenic,2279220,"Analysis of As- and Hg-Species in Metal-Resistant Oral Bacteria, by Imaging ToF-SIMS Abstract: Bacterial strains were isolated from the oral cavity of healthy volunteers and grown in the presence of Hg-ions (1-10 ppm) or arsenate ions at concentrations of 0.1-1.0%. To elucidate how bacteria take up and transform toxic metals inside the cells, we performed ion imaging and depth profiling with time-of-flight secondary ion mass spectrometry (ToF-SIMS). This analysis relies on the use of a pulsed ion beam to ionize surface molecules that can be extracted into a time-of-flight mass spectrometer. By combining the pulsed ion beam with another ion beam in direct current (DC) mode, depth profiles are obtained as a result of consecutive removal of surface layers. The spatial resolution of the depth profile along the y-axis is in the range of a few nanometres, and the spatial resolution along the x- and z-axes is in the ?m range. The ToF-SIMS analysis was performed on crude biofilms of bacteria air-dried at aluminium foil surfaces, allowing subcellular resolution along the y-axis. The mercury ions were found transformed to methylmercury preferably in the periplasmic space, and the arsenate ions were found reduced to arsenite inside the cells, close to the cell membrane. The data are discussed in relation to current concepts in bacterial resistance to metals and antibiotics.",
Arsenic,1032540,"Intracellular distribution and chemical forms of arsenic in rabbits exposed to arsenate Abstract: Inhibition of the methylation of arsenic in rabbits by ip injection of periodate-oxidized adenosine (PAD) prior to an iv injection of 74As-arsenate (AsV; 0.4 mg As/kg body wt) caused a marked increase in the retention of 74As in both the cellular organelles and the soluble fractions of liver and kidney. One day after exposure, almost 30% of the arsenic in the liver and about 40% of the arsenic in the kidney was recovered in the nuclear fraction. In the liver nuclei, the inhibition of the methylation increased the 74As content of the insoluble fraction and most of this arsenic was protein-bound. The major part of the soluble intranuclear 74As was in the form of AsIII, formed by reduction of the administered AsV. In the liver, PAD also caused a pronounced increase in the 74As content of the microsomal fraction. In the kidneys, where most of the arsenic was present as AsV, there was a marked accumulation of arsenic in the mitochondria.",
Arsenic,1015659,"Inflammatory responses induced by fluoride and arsenic at toxic concentration in rabbit aorta Abstract: Epidemiological and experimental studies have demonstrated the atherogenic effects of environmental toxicant arsenic and fluoride. Inflammatory mechanism plays an important role in the pathogenesis of atherosclerosis. The aim of the present study is to determine the effect of chronic exposure to arsenic and fluoride alone or combined on inflammatory response in rabbit aorta. We analyzed the expression of genes involved in leukocyte adhesion [P-selectin (P-sel) and vascular cell adhesion molecule-1(VCAM-1)], recruitment and transendothelial migration of leukocyte [interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1)] and those involved in pro-inflammatory cytokines [interleukin-6 (IL-6)]. We found that fluoride and arsenic alone or combined increased the expression of VCAM-1, P-sel, MCP-1, IL-8, and IL-6 at the RNA and protein levels. The gene expressions of inflammatory-related molecules were attenuated when co-exposure to the two toxicants compared with just one of them. We also examined the lipid profile of rabbits exposed to fluoride and (or) arsenic. The results showed that fluoride slightly increased the serum lipids but arsenic decreased serum triglyceride. We showed that inflammatory responses but not lipid metabolic disorder may play a crucial role in the mechanism of the cardiovascular toxicity of arsenic and fluoride.",
Arsenic,710984,"Manganese, arsenic, and infant mortality in Bangladesh: An ecological analysis Abstract: Recent studies in Bangladesh indicate that arsenic and manganese in tube-well water may increase the incidence of infant mortality. The study reported here examined whether these findings could be replicated. Data available from some 600 villages under the care of the nongovernmental organization (NGO) Gonoshasthaya Kendra included details of 29744 live births and 934 infant deaths in a 2-year period, with age and cause. These were analyzed by mean well levels of arsenic and manganese as reported by the British Geological Survey for the 12 upazillas. Odds ratios were calculated by age at death and cause. The effect of arsenic on all-cause infant mortality, although small and not significant, was consistent with earlier reports. The previous finding of an increased risk of infant mortality at concentrations of manganese &gt; or =0.4 mg/L was not evident.",
Arsenic,1519086,"Microbial arsenic methylation in soil and rice rhizosphere Abstract: Methylated arsenic (As) species are a common constituent of rice grains accounting for 10-90% of the total As. Recent studies have shown that higher plants are unlikely to methylate As in vivo suggesting that As methylation is a microbial mediated process that occurs in soils prior to plant uptake. In this study, we designed primers according to the conserved essential amino acids and structural motifs of arsenite S-adenosylmethionine methyltransferase (ArsM). We report for the first time the successful amplification of the prokaryotic arsM gene in 14 tested soils with wide ranging As concentrations. The abundance and diversity of the arsM gene in the rice rhizosphere soil and roots were analyzed using the designed primers. Results showed that microbes containing arsM genes were phylogenetically diverse, as revealed by the clone library and terminal restriction fragment length polymorphism (T-RFLP) analysis, and were branched into various phyla. Concentration of methylated As species in the soil solution was elevated in the rhizosphere soil and also by the addition of rice straw into the paddy soil, corresponding to the elevated abundance of the arsM gene in the soil. These results, together with evidence of horizontal gene transfer (HGT) of the arsM gene, suggest the genes encoding ArsM in soils are widespread. These findings demonstrate why most rice, when compared with other cereals, contains unusually high concentrations of methylated As species.",
Arsenic,1509353,"Approximate bilateral symmetry in evaporation-induced polycrystalline structures from droplets of wheat grain leakages and fluctuating asymmetry as quality indicator Abstract: The present paper reports on an observation that dendrite-like polycrystalline structures from evaporating droplets of wheat grain leakages exhibit bilateral symmetry. The exactness of this symmetry, measured by means of fluctuating asymmetry, varies depending on the cultivar and stress factor influence, and seems to correspond to the seed germination rate. In the bodies of plants, animals, and humans, the exactness of bilateral symmetry is known to reflect the environmental conditions of an organism's growth, its health, and its success in sexual selection. In polycrystalline structures, formed under the same conditions, the symmetry exactness depends on the properties of the crystallizing solution such as the composition and viscosity; however, it has never been associated with sample quality. We hypothesize here that, as in living nature, the exactness of approximate bilateral symmetry might be considered a quality indicator also in crystallographic methods applied to food quality analysis.",
Arsenic,1337875,"Effects of common competing anions on the adsorption of As(III) by ?-MnO2 and goethite Abstract: Batch experiments had been conducted to study the effects of PO43–, HPO42–, H2PO4–, SiO32–, SO42– and Cl– on the adsorption of As(III) by the d-MnO2 and the goethite. Moreover, the influential mechanisms of anions had been discussed. First, when the concentration of As(III) was low (10 mg/L), the effects of PO43– and SiO32– on the adsorption of As(III) by the d-MnO2 were notable and relative small effects of HPO42– and H2PO4– were suggested. PO43–, SiO32– and H2PO4– could affect the adsorption of As(III) by the goethite and the effect of HPO42– could be negligible. Both SO42– and Cl– had negligible competing adsorption to As(III) by the d-MnO2 and the goethite. The effects of anions on the As(III) adsorption by the d-MnO2 were more severe than that by the goethite. Then, when the concentration of As(III) varied from 0-85 mg/L, compared to the blank, all the anions performed their effects to As(III) absorption by the d-MnO2 and the goethite and the effects were more severe in high concentration than that in low concentration. The effects to the goethite were also obvious than that to the d-MnO2 in high concentration. Lastly, for the d-MnO2 and the goethite, SiO32– magnified the effect of PO43–. For the goethite, the combined effect of SiO32– and PO43– was more remarkable. The difference was decided by the structure characteristic of sorbent themselves, the d-MnO2 had more adsorptive capacity while the goethite had strong adsorptive affinity to As(III).",
Arsenic,1936109,"Effectiveness of zinc in modulating perinatal effects of arsenic on the teratological effects in mice offspring Abstract: Exposure to arsenic via drinking water is considered as a worldwide problem. Studies have shown that arsenic exposure during pregnancy affects embryogenesis and offspring development in rats and mice. Zinc as a micronutrient regulates many physiological functions, including an antioxidative role under various toxic conditions. However, studies on the perinatal protective effect of zinc on offspring need further attention. The present study was designed to evaluate the potential protective role of zinc in mitigating the adverse effects in the offspring of arsenic exposure during pregnancy. The arsenic (40mg/kg body weight) and zinc (4% w/v) doses formed the only drinking fluid source for the experimental groups of dams during the perinatal period of the experiment. The early development of sensory motor coordination reflexes together with morphological development in the male pups was measured during the weaning period. In adolescence, the offspring were tested for their motor behavior. The enzyme ?-glutamyl transferase (?-GT) and the oxidative stress indices like reduced glutathione (GSH) and lipid peroxidation (TBARS) were also estimated in the serum of the young adult male mice. Perinatal arsenic exposure caused depletion in body weight gain, delay in morphological development and retardation in the development of all sensory motor reflexes of the pups. In young adults, significant decrease in motor behavior with significant decrease in GSH level in the serum was observed. On the other hand, ?-GT and TBARS were significantly increased in the serum due to arsenic treatment. However, animals exposed to arsenic in the presence of zinc showed a remarkable ameliorating effect of zinc on all observed teratological and biochemical arsenic toxicity in male offspring. It was observed that zinc has an antioxidative role in the perinatal toxicity of arsenic. It is concluded from the present study that zinc consumed during the perinatal period of pregnancy can ameliorate the possible toxicities of arsenic exposure in the offspring by acting as an ameliorative supplement.",
Arsenic,2347803,"Size-controlled synthesis of uniform akaganeite nanorods and their encapsulation in alginate microbeads for arsenic removal Abstract: Uniform, size-controllable akaganeite nanorods were synthesized by hydrolysis of ferric ions in a two-phase system using sodium oleate as a surfactant. The akaganeite nanorods encapsulated in alginate microbeads showed quick, easy arsenic removal from highly contaminated water, indicating their potential for purification of groundwater in developing countries.",
Arsenic,627997,"Arsenic intoxication-induced reduction of glutathione level and of the activity of related enzymes in rat brain regions: reversal by DL-alpha-lipoic acid Abstract: The purpose of this study was to examine the effects of DL: -alpha-lipoic acid (LA) on arsenic (As) induced alteration of glutathione (GSH) level and of the activity of glutathione-related enzymes-glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G6PDH)-in rat brain regions (cortex, hypothalamus, striatum, cerebellum and hippocampus). Male Wistar rats of 150+/-10 g weight were divided into four groups: control and three experimental groups supplemented with arsenic (sodium arsenite) alone (100 ppm mixed in drinking water), lipoic acid alone (70 mg kg(-1) body weight), arsenic plus lipoic acid (100 ppm arsenic in drinking water plus 70 mg lipoic acid kg(-1) body weight). The arsenic content of brain regions was found to increase with the administration of sodium arsenite. Arsenic exposure elicited a significant decline in glutathione content and in the activity of related enzymes, with the greatest decreases seen in the cortex, striatum, and hippocampus, whereas there were no significant differences between control rats and the group treated with lipoic acid alone. Highly elevated content of the thiobarbituric acid-reactive substance malondialdehyde (MDA) in the brain regions of arsenic-exposed rats reflected extensive lipid peroxidation (LPO) processes. Simultaneous lipoic acid treatment was effective in reducing brain regional arsenic levels and lipid peroxidation and in increasing the glutathione content and the activity of its related enzymes. Lipoic acid, by acting as an alternative sulfhydryl nucleophile to glutathione, prevents its oxidation to glutathione disulfide in detoxifying reactions against reactive oxygen species and consequently increases the activity of glutathione-related enzymes.",
Arsenic,1356875,"Lipid Peroxidation And Distribution Of Inorganic Arsenic And Its Metabolites In Rat Nervous System Abstract: In environmentally exposed humans to inorganic arsenic (iAs) it has been observed a deficit in attention, memory and learning habilities as well as peripheral neuropathies. Rodents exposed to iAs have been showed changes in several brain neurotransmitter systems and alterations in the locomotor activity. These effects have been associated to the presence of arsenic in cerebral tissue. In the present study we analyze the possible relationship between lipid peroxidation (LPO) and distribution of iAs and its metabolites (monomethyl arsenic, MMA and dimethyl arsenic, DMA) in several structures of the rat nervous system (brain, spinal cord, sciatic and sural nerves). Sodium arsenite diluted in water (10 mg/kg/day) was dosed to male Wistar rats (200-300 gr bw) during 30 days, by gavage. iAs and its metabolites concentrations were determined. Results indicated the DMA was the major iAs metabolite in nervous tissues (~95%)and it was higher in peripheral than in central nervous structures (sural nerve>sciatic nerve>spinal cord ~=brain). LPO, expressed by means of malondialdehyde content (MDA), was also observed in rat nervous tissues and it significantly differs from control group (p<0.0001). In addition, MDA content show a close relationship with the arsenic concentration observed in all nervous tissues. Our results may indicated that the presence of DMA induce the formation of MDA and in consequence, the occurrence of oxidative stress in peripheral and central nervous tissues. In addition, our observations also illustrate the existance of a differential distribution of arsenic in peripheral nerves and spinal cord of the exposed rat.",
Arsenic,1030898,"Repeated surveillance of exposure to cadmium, manganese, and arsenic in school-age children living in rural, urban, and nonferrous smelter areas in Belgium Abstract: Once a year from 1974 to 1978, the intensity of exposure to Cd, As, Mn in groups of school-age children living around a lead smelter was assessed. By comparison, groups of children living in an urban and a rural area were also examined. The metal content of blood, urine, hand-rinsing, air, dust, and dirt collected in the school-playground was compared. The urinary excretion of cadmium in children living around the lead smelter is greater than in those living in the urban and in the rural area. In the latter there seems to exist a time-dependent trend in the renal accumulation of cadmium. This suggests that the overall pollution of the environment by cadmium in Belgium is progressively increasing. In the smelter area, both the oral and pulmonary routes play a role in the children's exposure to cadmium. Their relative contribution to the amount of cadmium absorbed appears similar. The concentration of arsenic in urine of children living around the smelter is significantly higher than that of rural children. Speciation of the chemical forms of arsenic in urine indicates that the difference is not due to different dietary habits of the children examined but to different intensity of exposure to inorganic arsenic. The amount of arsenic on the hand of children living at less than 1 km from the smelter (X = 17.6 ?g As/hand) was more than 10 times that found in children living at 2.5 km from the plant (X = 1.5 ?g As/hand) whereas that found in children living in urban and rural areas was below 0.2 ?g As/hand. The arsenic concentration of dust and dirt collected in the school-playground in the different areas follows the same trend. As expected, there are strong interrelationships between the degree of hand contamination by lead, cadmium, and arsenic (r ? 0.8). No statistically significant influence of the dwelling place of the children on the manganese level in blood, urine, and hand rinsing was found. Our results demonstrate that by comparison with the rural and urban children, those living in the vicinity of a nonferrous smelter may be more exposed not only to lead, but also to cadmium and arsenic. The possible long-term effects of such exposure deserve further evaluation.",
Arsenic,596330,"Use of the Syrian hamster embryo cell transformation assay for determining the carcinogenic potential of heavy metal compounds Abstract: Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, vanadium pentoxide, and nickel sulfate heptahydrate were tested in the Syrian hamster embryo (SHE) assay in order to increase the SHE assay database for heavy metals. All five compounds produced significant morphological transformation at one or more doses in a dose-responsive manner. Cobalt sulfate hydrate, gallium arsenide, molybdenum trioxide, and nickel (II) sulfate heptahydrate were all positive with a 24-hr exposure, suggesting direct DNA perturbation. Vanadium pentoxide was negative with a 24-hr exposure, but positive with a 7-day exposure. This pattern of response (24-hr SHE negative/7-day SHE positive) has been seen with other chemicals which have tumor promotion-like characteristics. Since the inception of the use of the SHE cell transformation assay for detecting the neoplastic transformation potential of chemicals, over 42 heavy metal compounds have been tested in this assay. Based on the 24 metal compounds which have been tested in the SHE, Salmonella, and some type of rodent bioassay, the SHE assay is 92% concordant with rodent bioassay carcinogenicity results, including a sensitivity of 95% (21/22) and a specificity of 50% (1/2). At this time, the measure of SHE assay specificity for rodent carcinogenicity of metals is limited by the paucity of metal compounds which are rodent noncarcinogens. The Salmonella assay results are only 33% concordant with the rodent bioassay for these same chemicals. This relatively high concordance between the SHE assay and the rodent bioassay carcinogenicity results demonstrates the utility of the SHE assay for determining the carcinogenic potential of heavy metal compounds in rodent cancer bioassays.",
Arsenic,1033270,Napoleon Bonaparte's exposure to arsenic during 1816 Abstract: Analysis of hair from Napoleon showed that he was exposed to considerable amounts of arsenic during 1816. The distribution pattern of the arsenic in the hair is similar to that found after the daily ingestion of excessive amounts of arsenic.,
Arsenic,1465769,"Transcriptional modulation of the ERK1/2 MAPK and NF-KB pathways in human urothelial cells after trivalent arsenical exposure: implications for urinary bladder cancer Abstract: Chronic exposure to drinking water contaminated with inorganic arsenic (iAs) is associated with an increased risk of urinary bladder (UB) cancers in humans. The exact role of specific iAs metabolite(s) in As-mediated carcinogenesis remains largely unknown. Experimental evidence suggests that trivalent arsenicals, namely arsenite (iAsIII) and two of its metabolites, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), are possible proximate UB carcinogens. Here, we used a transcriptomics approach to examine perturbed molecular pathways in a human urothelial cell line (UROtsa) after short-term exposure to iAsIII, MMAIII and DMAIII. Molecular pathways containing genes that encode proteins implicated in UB cancer development were perturbed by both MMAIII and DMAIII. These pathways included those of the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase (ERK 1/2 MAPK) and nuclear factor kappa beta (NF-kB). Together, these results may inform the current understanding of effects in the UB induced by acute As exposure and the relationship of these effects with As-mediated carcinogenesis.",
Arsenic,1936075,"Model-based integration and analysis of biogeochemical and isotopic dynamics in a nitrate-polluted pyritic aquifer Abstract: Leaching of nitrate from agricultural land to groundwater and the resulting nitrate pollution are a major environmental problem worldwide. Its impact is often mitigated in aquifers hosting sufficiently reactive reductants that can promote autotrophic denitrification. In the case of pyrite acting as reductant, however, denitrification is associated with the release of sulfate and often also with the mobilization of trace metals (e.g., arsenic). In this study, reactive transport modeling was used to reconstruct, quantify and analyze the dynamics of the dominant biogeochemical processes in a nitrate-polluted pyrite-containing aquifer and its evolution over the last 50 years in response to changing agricultural practices. Model simulations were constrained by measured concentration depth profiles. Measured 3H/3He profiles were used to support the calibration of flow and conservative transport processes, while the comparison of simulated and measured sulfur isotope signatures acted as additional calibration constraint for the reactive processes affecting sulfur cycling. The model illustrates that denitrification largely prevented an elevated discharge of nitrate to surface waters, while sulfate discharges were significantly increased, peaking around 15 years after the maximum nitrogen inputs.",
Arsenic,2345633,"Arsenic speciation in rice-based food for adults with celiac disease Abstract: Celiac disease (CD) may affect up to 1% of the Western population. It is a disease whose diagnosis has been made mainly in childhood, but now the profile has changed, with one out of five newly diagnosed individuals being over 65 years old. The only treatment for this population is a gluten-free diet. Therefore, the objective of this study was to analyze the occurrence of arsenic (As) in gluten-free products, basically those rice-based, intended for celiac adult consumers. The current study demonstrated that these rice-based products contained important contents of total arsenic (t-As) (up to 120 ?g kg(-1)) and inorganic arsenic (i-As) (up to 85.8 ?g kg(-1)). It was estimated that the contents of t-As and i-As in rice used as the main ingredient of these foods were as high as 235 and 198 ?g kg(-1), respectively. The estimated daily intake of i-As was 0.46 and 0.45 ?g kg(-1) bw in women and men of 58 and 75 kg of body weight (bw), respectively. These values indicate that a health risk to these consumers cannot be excluded. Finally, legislation is needed to delimit the safety intake by the Health Agencies and to improve the labeling of these special rice-based foods for celiac adult consumers. The label should include information about percentage, geographical origin, and cultivar of the rice used; besides and if companies want to clearly prove the safety of their products the exact content of i-As should also be included.",
Arsenic,2345657,"Prospecting for hyperaccumulators of trace elements: a review Abstract: Specific plant species that can take up and accumulate abnormally high concentrations of elements in their aboveground tissues are referred to as &quot;hyperaccumulators&quot;. The use of this term is justified in the case of enormous element-binding capacity of plants growing in their natural habitats and showing no toxicity symptoms. An increasing interest in the study of hyperaccumulators results from their potential applications in environmental biotechnology (phytoremediation, phytomining) and their emerging role in nanotechnology. The highest number of plant species with confirmed hyperaccumulative properties has been reported for hyperaccumulators of nickel, cadmium, zinc, manganese, arsenic and selenium. More limited data exist for plants accumulating other elements, including common pollutants (chromium, lead and boron) or elements of commercial value, such as copper, gold and rare earth elements. Different approaches have been used for the study of hyperaccumulators - geobotanical, chemical, biochemical and genetic. The chemical approach is the most important in screening for new hyperaccumulators. This article presents and critically reviews current trends in new hyperaccumulator research, emphasizing analytical methodology that is applied in identification of new hyperaccumulators of trace elements and its future perspectives.",
Arsenic,1029992,Scanning with positron-emitting isotopes in cerebrovascular disease Abstract: ,
Arsenic,1936039,"Trace metal and metalloid levels in surface water of Marcal River before and after the Ajka red mud spill, Hungary Abstract: The aim of this study was to compare and assess the dissolved concentrations of trace elements (As, Zn, Hg, Cd, Cr, Ni, Pb and Cu) in surface water of Marcal River before and after the red mud spill that occurred in Ajka, western Hungary, in October 2010. The caustic sludge flooded the surrounding settlements and polluted the nearby Torna Creek, which flows through the Marcal and Raba rivers into the Danube. A total of 92 surface water samples were collected from the Marcal River in the period of 2007-2012 and analysed for dissolved trace metal(loid)s by atomic absorption spectroscopy method. After the spill, the water management authority initially focused on acid dosing of surface waters to lower pH and was effective in lowering both pH and metal(loid) concentrations. Among the dissolved trace metal(loid)s, arsenic and nickel levels were moderately higher in the Marcal River 2 years since the spill compared to that observed in the pre-disaster period. The concentrations of dissolved trace metal(loid)s did not exceed the European water quality standards and the US Environmental Protection Agency aquatic life criteria values (excluding one sample for cadmium).",
Arsenic,1349173,DIFFERENTIAL-EFFECTS OF PRETREATMENT AND POSTTREATMENT OF SODIUM ARSENITE ON THE GENOTOXICITY OF METHYL METHANESULFONATE IN CHINESE-HAMSTER OVARY CELLS Abstract: ,
Arsenic,1797820,"Contribution of diet to aggregate arsenic exposures-An analysis across populations Abstract: The relative contribution of dietary arsenic (As) to aggregate daily exposure has not been well-characterized, especially in relation to the current EPA maximum contaminant level (MCL) of 10?p.p.b. for As in drinking water. Our objectives were to: (1) model exposure to inorganic and total As among non-seafood eaters using subject-specific data, (2) compare the contribution of food, drinking and cooking water to estimated aggregate exposure in households with variable background tap water As levels, and (3) describe the upper distribution of potential dose at different thresholds of tap water As. Dietary As intake was modeled in regional study populations and NHANES 2003-2004 using dietary records in conjunction with published food As residue data. Water As was measured in the regional studies. Among subjects exposed to tap water As >10?p.p.b., aggregate inorganic exposure was 24.5-26.1??g/day, with approximately 30% of intake from food. Among subjects living in homes with tap water As ?10, 5 or 3?p.p.b., aggregate inorganic As exposure was 8.6-11.8??g/day, with 54-85% of intake from food. Median inorganic As potential dose was 0.42-0.50??g/kg BW/day in subjects exposed to tap water As >10?p.p.b. and less than half that among subjects exposed to tap water As ?10?p.p.b. The majority of inorganic and total As exposure is attributable to diet in subjects with tap water As <MCL. Further research is needed to determine the potential toxicity and need for regulation of As in foods.",
Arsenic,2337140,"Occurrence of inorganic arsenic in edible Shiitake (Lentinula edodes) products Abstract: The present study reports arsenic speciation analysis in edible Shiitake (Lentinula edodes) products. The study focused on the extraction, and accurate quantification of inorganic arsenic (iAs), the most toxic form of arsenic, which was selectively separated and determined using anion exchange LC-ICPMS. A wide variety of edible Shiitake products (fresh mushrooms, food supplements, canned and dehydrated) were purchased and analysed. A cultivated Shiitake grown under controlled conditions was also analysed. The extraction method showed satisfactory extraction efficiencies (&gt;90%) and column recoveries (&gt;85%) for all samples. Arsenic speciation revealed that iAs was the major As compound up to 1.38mgAskg(-1)dm (with a mean percentage of 84% of the total arsenic) and other organoarsenicals were found as minor species. Shiitake products had high proportions of iAs and therefore should not be ignored as potential contributors to dietary iAs exposure in populations with a high intake of Shiitake products.",
Arsenic,1028976,"Metallomics study using hair mineral analysis and multiple logistic regression analysis: relationship between cancer and minerals Abstract: <strong>OBJECTIVES: </strong>The objective of this metallomics study is to investigate comprehensively some relationships between cancer risk and minerals, including essential and toxic metals.<br /><br /><strong>METHODS: </strong>Twenty-four minerals including essential and toxic metals in scalp hair samples from 124 solid-cancer patients and 86 control subjects were measured with inductively coupled plasma mass spectrometry (ICP-MS), and the association of cancer with minerals was statistically analyzed with multiple logistic regression analysis.<br /><br /><strong>RESULTS: </strong>Multiple logistic regression analysis demonstrated that several minerals are significantly correlated to cancer, positively or inversely. The most cancer-correlated mineral was iodine (I) with the highest correlation coefficient of r = 0.301, followed by arsenic (As; r = 0.267), zinc (Zn; r = 0.261), and sodium (Na; r = 0.190), with p &lt; 0.01 for each case. In contrast, selenium (Se) was inversely correlated to cancer (r = -0.161, p &lt; 0.05), followed by vanadium (V) (r = -0.128). Multiple linear regression value was highly significantly correlated with probability of cancer (R (2) = 0.437, p &lt; 0.0001), and the area under the receiver-operating characteristic (ROC) curve was calculated to be 0.918. In addition, using contingency table analysis and the chi-square test, the precision of discrimination for cancer was estimated to be 0.871 (chi-square = 99.1, p &lt; 0.0001).<br /><br /><strong>CONCLUSIONS: </strong>These findings suggest that some minerals such as arsenic, selenium, and probably iodine, zinc, sodium, and vanadium contribute to regulation of cancer and also that metallomics study using multiple logistic regression analysis is a useful tool for estimating cancer risk.",
Arsenic,1579296,"Arsenic Levels and Speciation from Ingestion Exposures to Biomarkers in Shanxi, China: Implications for Human Health Abstract: Chronic exposure to arsenic (As) threatens human health. To systematically understand the health risks induced by As ingestion, we explored water and diet contributions to As exposure, and compared As in biomarkers and the arsenicosis in a geogenic As area in China. In this study, high percentages of water (77% of n = 131 total samples), vegetables (92%, n = 120), cereals (32%, n = 25), urine (70%, n = 99), nails (76%, n = 176), and hair (62%, n = 61) contained As higher than the acceptable levels. Dietary As contributed 92% of the average daily dose (ADD) when the water As concentration was less than 10 ?g/L, for which 5 out of 30 examined participants were diagnosed with arsenicosis symptoms. The distinct positive correlation between ADD and As concentrations in urine, nails, and hair suggests different applicability for these biomarkers. Methylated As as the predominant urinary As species confirms that the ingested inorganic As is methylated and is excreted through urine. In situ microdistribution and speciation analysis indicates that As is mainly associated with sulfur in nails and hair. Nails, rather than hair and urine, could be used as a proper biomarker for arsenicosis. High ADD from the environment and low excretion could result in As toxicity to humans.",
Arsenic,1797780,"Evaluation of radiological prognostic factors of hepatic metastases in patients with non-functional pancreatic neuroendocrine tumors Abstract: <strong>PURPOSE: </strong>There are different therapeutic options in non-functional well to moderately differentiated (G1 and G2) pancreatic neuroendocrine tumors (pNET) with unresectable hepatic metastases including systemic chemotherapy and novel molecular targeted therapies. Treatment with somatostatin analogs (SSA) as antiproliferative agents is optional. At initial diagnosis watchful waiting until tumor progression is a well-established approach. Goal of this study was to evaluate imaging features as potential prognostic factors predicting early tumor progression in order to select patients that might benefit from an earlier initiation of medical treatment.<br /><br /><strong>PATIENTS AND METHODS: </strong>In 44 patients we correlated tumor grade, chromogranin A (CgA) levels, treatment with SSA and imaging features of hepatic metastases on contrast-enhanced multiphase CT and MR imaging with time to tumor progression (TTP) according to RECIST 1.0.<br /><br /><strong>RESULTS: </strong>In the total patient cohort none of the tested imaging features was found to be a statistically significant prognostic factor for TTP. Since treatment with SSA was associated with an increased TTP we also analyzed a subgroup of 30 patients not treated with SSA. In this subgroup of patients hypoenhancement of hepatic metastases during early contrast phases was found to be a negative prognostic factor for early tumor progression within 12 months (p=0.039). The other evaluated parameters including hepatic tumor load, number of metastases, and presence of regressive morphological changes did not reveal significant results.<br /><br /><strong>CONCLUSION: </strong>Hypovascularization of liver metastases from G1 and G2 pNET reflected by hypoenhancement during the early contrast phases seems to be associated with early tumor progression. In patients with hypoenhancing metastases repeated biopsy for reassessment of grading of these metastases, and early initiation of therapy should be considered.",
Arsenic,2337267,"Characterization of protein, lipid and mineral contents in common Norwegian seaweeds and evaluation of their potential as food and feed Abstract: <strong>BACKGROUND: </strong>The objectives of this study were to examine protein and amino acid composition, lipid and fatty acid composition, along with a range of essential minerals in common Norwegian seaweed species representing the red (Palmaria palmata and Vertebrata lanosa), green (Cladophora rupestris, Enteromorpha intestinalis and Ulva lactuca) and brown (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Fucus vesiculosus and Pelvetia canaliculata) classes and assess their potential as alternatives to cereals in food and feed. As macroalgae accumulate heavy metals, arsenic, cadmium and mercury were also analyzed.<br /><br /><strong>RESULTS: </strong>Proteins ranged from 34 to 123?g?kg(-1) dry weight (DW) and the essential amino acid levels may cover both human and salmonid requirements. Lipids were low (6-58?g?kg(-1) DW), but the red algae had high relative content of long-chained omega-3 fatty acids (32-34 % of the fatty acids). Iodine contents were particularly high in the Laminaria species. Of the heavy metals only arsenic levels may be of concern.<br /><br /><strong>CONCLUSION: </strong>In total, the red alga P. palmata was regarded as the best alternative to cereals in food and feed. For several of the other species, single-component extraction for the ingredients market may be better than using the whole product. © 2014 Society of Chemical Industry.",
Arsenic,1032254,"Chemical and molecular regulation of enzymes that detoxify carcinogens Abstract: Inductions of detoxication (phase 2) enzymes, such as glutathione transferases and NAD(P)H:(quinone-acceptor) oxidoreductase, are a major mechanism for protecting animals and their cells against the toxic and neoplastic effects of carcinogens. These inductions result from enhanced transcription, and they are evoked by diverse chemical agents: oxidizable diphenols and phenylenediamines; Michael reaction acceptors; organic isothiocyanates; other electrophiles--e.g., alkyl and aryl halides; metal ions--e.g., HgCl2 and CdCl2; trivalent arsenic derivatives; vicinal dimercaptans; organic hydroperoxides and hydrogen peroxide; and 1,2-dithiole-3-thiones. The molecular mechanisms of these inductions were analyzed with the help of a construct containing a 41-bp enhancer element derived from the 5' upstream region of the mouse liver glutathione transferase Ya subunit gene ligated to the 5' end of the isolated promoter region of this gene, and inserted into a plasmid containing a human growth hormone reporter gene. When this construct was transfected into Hep G2 human hepatoma cells, the concentrations of 28 compounds (from the above classes) required to double growth hormone production, and the concentrations required to double quinone reductase specific activities in Hepa 1c1c7 cells, spanned a range of four orders of magnitude but were closely linearly correlated. Six compounds tested were inactive in both systems. A 26-bp subregion of the above enhancer oligonucleotide (containing the two tandem &quot;AP-1-like&quot; sites but lacking the preceding ETS protein binding sequence) was considerably less responsive to the same inducers. We conclude that the 41-bp enhancer element mediates most, if not all, of the phase 2 enzyme inducer activity of all of these widely different classes of compounds.",
Arsenic,1326911,"Arsenite suppression of involucrin transcription through AP1 promoter sites in cultured human keratinocytes Abstract: While preserving keratinocyte proliferative ability, arsenite suppresses cellular differentiation markers by preventing utilization of AP1 transcriptional response elements. In present experiments, arsenite had a dramatic effect in electrophoretic mobility supershift analysis of proteins binding to an involucrin promoter AP1 response element. Without arsenite treatment, binding of JunB and Fra1 was readily detected in nuclear extracts from preconfluent cultures and was not detected a week after confluence, while c-Fos was detected only after confluence. By contrast, band shift of nuclear extracts from arsenite treated cultures showed only JunB and Fra1 binding in postconfluent as well as preconfluent cultures. Immunoblotting of cell extracts showed that arsenite treatment prevented the loss of Fra1 and the increase in c-Fos proteins that occurred after confluence in untreated cultures. Chromatin immunoprecipitation assays demonstrated substantial reduction of c-Fos and acetylated histone H3 at the proximal and distal AP1 response elements in the involucrin promoter and of coactivator p300 at the proximal element. Alteration of AP1 transcription factors was also examined in response to treatment with four metal containing compounds (chromate, vanadate, hemin, divalent cadmium) that also suppress involucrin transcription. These agents all influenced transcription at AP1 elements in a transcriptional reporter assay, but exhibited less effect than arsenite on binding activity assessed by mobility shift and chromatin immunoprecipitation and displayed variable effects on AP1 protein levels. These findings help trace a mechanism by which transcriptional effects of arsenite become manifest and help rationalize the unique action of arsenite, compared to the other agents, to preserve proliferative ability.",
Arsenic,1354990,"Tumor necrosis factor alpha (TNFalpha) induces the unfolded protein response (UPR) in a reactive oxygen species (ROS)-dependent fashion, and the UPR counteracts ROS accumulation by TNFalpha Abstract: Accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER overload, resulting in ER stress. To cope with ER stress, mammalian cells trigger a specific response known as the unfolded protein response (UPR). Although recent studies have indicated cross-talk between ER stress and oxidative stress, the mechanistic link is not fully understood. By using murine fibrosarcoma L929 cells, in which tumor necrosis factor (TNF) alpha induces accumulation of reactive oxygen species (ROS) and cell death, we show that TNFalpha induces the UPR in a ROS-dependent fashion. In contrast to TNFalpha, oxidative stresses by H2O2 or arsenite only induce eukaroytic initiation factor 2alpha phosphorylation, but not activation of PERK- or IRE1-dependent pathways, indicating the specificity of downstream signaling induced by various oxidative stresses. Conversely, the UPR induced by tunicamycin substantially suppresses TNFalpha-induced ROS accumulation and cell death by inhibiting reduction of cellular glutathione levels. Collectively, some, but not all, oxidative stresses induce the UPR, and pre-emptive UPR counteracts TNFalpha-induced ROS accumulation.",
Arsenic,1354272,ESTIMATION OF ARSENIC IN GEOLOGICAL SAMPLES BY ATOMIC-ABSORPTION SPECTROMETRY Abstract: ,
Arsenic,1704105,Effect of nicotinamide on ultraviolet radiation and arsenic-induced DNA damage Abstract: ,
Arsenic,1372540,Some comments on limit test for arsenic in iron and ammonium citrate IP Abstract: IPA COPYRIGHT: ASHP Deficiencies in the Indian Pharmacopeia methods for detecting arsenic in ferric ammonium citrate are briefly discussed. It was suggested that the IP method be modified to the BP method which detects limits of arsenic ranging down to 4 ppm.,
Arsenic,1339986,"Cupriavidus alkaliphilus sp. nov., a new species associated with agricultural plants that grow in alkaline soils Abstract: A group of 20 bacterial strains was isolated from the rhizosphere of different agricultural plants growing in alkaline soils in the northeast of Mexico. The phylogenetic analysis of the 16S rRNA gene sequence from four strains showed that this novel group belonged to the Cupriavidus genus, with C. taiwanensis (?98.9%) and C. necator (?98.8%) as the closest species. However, DNA-DNA reassociation values were less than 20%. The novel group did not fix nitrogen and lacked nifH and nodA genes, unlike C. taiwanensis. Whole-cell protein patterns were highly similar among the 20 strains but different from the closest Cupriavidus species. BOX-PCR patterns were distinct among the 20 strains but also differed from other Cupriavidus type species. The major cellular fatty acids from strains ASC-732(T) and SLV-2362 were C(16:0), C(18:1) ?7c/12t/9t and C(16:1) ?7c and/or C(15:0) iso 2OH. The major polar lipids consisted of phosphatidylglycerol, cardiolipin, phosphatidylethanolamine, 2-hydroxylated-phosphatidylethanolamine and an unknown aminolipid. The DNA G+C content of strain ASC-732(T) was 66.8mol%. All 20 strains grew in the presence of 5-10mgmL(-1) arsenic, 1mgmL(-1) zinc, and 0.1mgmL(-1) copper. Consequently, the group of strains was considered to represent a novel species for which the name Cupriavidus alkaliphilus sp. nov. is proposed. The type strain is ASC-732(T) (=LMG 26294(T)=CIP 110330(T)).",
Arsenic,711021,"A prospective study of the synergistic effects of arsenic exposure and smoking, sun exposure, fertilizer use, and pesticide use on risk of premalignant skin lesions in Bangladeshi men Abstract: Skin lesions are classic clinical signs of toxicity due to long-term exposure to arsenic, and they are considered precursors to arsenic-related skin cancer. The authors prospectively evaluated synergisms between effects of arsenic exposure and those of tobacco use, sun exposure, and pesticide and fertilizer use on incident skin lesions using risk factor data from 5,042 men from the Health Effects of Arsenic Longitudinal Study in Araihazar, Bangladesh, which recruited participants from October 2000 to May 2002. Discrete time hazard models were used to estimate measures of synergistic interactions on the additive scale. The authors observed significant synergistic effects between various measures of arsenic exposure and smoking and fertilizer use. The relative excess risks for the interactions between smoking status and arsenic exposure were 0.12 (95% confidence interval: 0.06, 0.19) for water arsenic and 0.11 (95% confidence interval: 0.05, 0.15) for urinary arsenic measures, respectively. Significant synergistic effects were also observed between fertilizer use and water arsenic (relative excess risk for the interaction = 0.06, 95% confidence interval: 0.01, 0.12). This is the first prospective study based on individual-level data that supports a role for smoking and certain occupational risk factors in modification of the effect of long-term arsenic exposure on skin lesions. Understanding differential arsenic susceptibility allows researchers to develop interventions to prevent the health consequences of this massive problem in the Bangladeshi population and beyond.",
Arsenic,1343984,"Preparation, spectroscopic characterization, and crystal and molecular structure of 1,3,2-benzothiazarsolium tetrachloroaluminate: A dicoordinate arsenic cation containing As-S and As-N p.pi.-bonding Abstract: ",
Arsenic,1018573,"Hypersensitivity to mitomycin C-induced sister chromatid exchange as a biomarker of past exposure to arsenic Abstract: The objective of this study was to determine if cytogenetic markers can be used as indicators of prior exposure to arsenic compounds. Baseline sister chromatid exchange (SCE) and mitomycin C-induced (MMC) SCE were measured in four study populations recruited from a blackfoot (BF) disease endemic area, including 22 patients with cancer (CA) only, 8 patients with both BF disease and CA (BF+CA), 10 patients with BF disease only, and 26 healthy residents (HRs). Another group of 23 healthy, nonarsenic-exposed workers were recruited as external healthy controls (HCs). Characteristics of study population were collected by questionnaire, and 10 ml of venous blood were drawn for lymphocyte culture. The results showed that the frequencies of baseline SCE did not differ among the five study groups. The frequencies of delta SCE (MMC-induced SCE minus baseline SCE) in CA only, BF disease only, and HRs, three arsenic-exposed groups, were significantly higher than in HCs. The frequency of delta SCE in the BF+CA group was nonsignificantly higher than in HCs, probably due to small sample size. The frequencies of both baseline SCE and delta SCE did not differ among CA only, BF disease only, BF+CA, and HR groups. The observation that baseline SCE did not increase in the arsenic-exposed populations indicates either that exposures were insufficiently high to change this marker or that lesions did not persist. The increased SCE response to MMC in arsenic-exposed populations suggests that previous arsenic exposure may result in hypersensitivity of human lymphocytes to carcinogens and/or mutagens. Both baseline SCE and delta SCE were not different among patients with arsenic-induced diseases and healthy normal residents, indicating that hypersensitivity may have been due to previous arsenic exposure but was not associated with disease status.",
Arsenic,1033785,Gas-sampling technique for arsenic determination by atomic absorption spectrophotometry Abstract: ,
Arsenic,627516,"Arsenic induces apoptosis through a c-Jun NH2-terminal kinase-dependent, p53-independent pathway Abstract: Arsenic has been used as an effective chemotherapy agent for some human cancers, such as acute promyelocytic leukemia. In this study, we found that arsenic induces activation of c-Jun NH2-terminal kinases (JNKs) at a similar dose range for induction of apoptosis in JB6 cells. In addition, we found that arsenic did not induce p53-dependent transactivation. Similarly, there was no difference in apoptosis induction between cells with p53 +/+ or p53 -/-. In contrast, arsenic-induced apoptosis was almost totally blocked by expression of a dominant-negative mutant of JNK1. These results suggest that the activation of JNKs is involved in arsenic-induced apoptosis of JB6 cells. Taken together with previous findings that p53 mutations are involved in approximately 50% of all human cancers and nearly all chemotherapeutic agents kill cancer cells mainly by apoptotic induction, we suggest that arsenic may be a useful agent for the treatment of cancers with p53 mutation.",
Arsenic,710988,"Mechanism of thiol-supported arsenate reduction mediated by phosphorolytic-arsenolytic enzymes: II. Enzymatic formation of arsenylated products susceptible for reduction to arsenite by thiols Abstract: Enzymes catalyzing the phosphorolytic cleavage of their substrates can reduce arsenate (AsV) to the more toxic arsenite (AsIII) via the arsenolytic substrate cleavage in presence of a reductant, as glutathione or dithiotreitol (DTT). We have shown this for purine nucleoside phosphorylase (PNP), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), glycogen phosphorylase-a (GPa), and phosphotransacetylase (PTA). Using a multidisciplinary approach, we explored the mechanism whereby these enzymes mediate AsV reduction. It is known that PNP cleaves inosine with AsV into hypoxanthine and ribose-1-arsenate. In presence of inosine, AsV and DTT, PNP mediates AsIII formation. In this study, we incubated PNP first with inosine and AsV, allowing the arsenolytic reaction to run, then blocked this reaction with the PNP inhibitor BCX-1777, added DTT and continued the incubation. Despite inhibition of PNP, large amount of AsIII was formed in these incubations, indicating that PNP does not reduce AsV directly but forms a product (i.e., ribose-1-arsenate) that is reduced to AsIII by DTT. Similar studies with the other arsenolytic enzymes (GPa, GAPDH, and PTA) yielded similar results. Various thiols that differentially supported AsV reduction when present during PNP-catalyzed arsenolysis (DTT approximately dimercaptopropane-1-sulfonic acid &gt; mercaptoethanol &gt; DMSA &gt; GSH) similarly supported AsV reduction when added only after a transient PNP-catalyzed arsenolysis, which preformed ribose-1-arsenate. Experiments with progressively delayed addition of DTT after BCX-1777 indicated that ribose-1-arsenate is short-lived with a half-life of 4 min. In conclusion, phosphorolytic enzymes, such as PNP, GAPDH, GPa, and PTA, promote thiol-dependent AsV reduction because they convert AsV into arsenylated products reducible by thiols more readily than AsV. In support of this view, reactivity studies using conceptual density functional theory reactivity descriptors (local softness, nucleofugality) indicate that reduction by thiols of the arsenylated metabolites is favored over AsV.",
Arsenic,626939,"Carcinogen exposure and gene promoter hypermethylation in bladder cancer Abstract: Tobacco smoking, certain occupational exposures, and exposure to inorganic arsenic in drinking water have been associated with the occurrence of bladder cancer. However, in these tumors the exposure-associated pattern of somatic alterations in genes in the causal pathway for disease has been poorly characterized. In particular, the mechanism by which arsenic induces bladder cancer and the effects of lower environmental levels of exposure remain uncertain. Animal and in-vitro studies have suggested that arsenic and other exposures may act through epigenetic mechanisms. We, therefore, examined, in a population-based study of human bladder cancer, the relationship between epigenetic silencing of three tumor suppressor genes, p16INK4A, RASSF1A and PRSS3, and exposure to both tobacco and arsenic in bladder cancer. Promoter methylation of each of these genes occurred in ~30% of bladder cancers, and both RASSF1A and PRSS3 promoter methylation were associated with advanced tumor stage (P < 0.001 and P < 0.04, respectively). Arsenic exposure, measured as toenail arsenic, was associated with RASSF1A (P < 0.02) and PRSS3 (P < 0.1) but not p16INK4A promoter methylation, in models adjusted for stage and other factors. Cigarette smoking was associated with a >2-fold increased risk of promoter methylation of the p16INK4A gene only, with greater risk seen in patients with exposures more recent to disease diagnosis. These results, from human bladder tumors, add to the body of animal and in vitro evidence that suggests a role in epigenetic alterations for bladder carcinogens.",
Arsenic,710980,"Low-level arsenic impairs glucose-stimulated insulin secretion in pancreatic beta cells: involvement of cellular adaptive response to oxidative stress Abstract: Chronic exposure of humans to inorganic arsenic, a potent environmental oxidative stressor, is associated with incidence of type 2 diabetes (T2D). A key driver in the pathogenesis of T2D is impairment of pancreatic beta-cell function, with the hallmark of beta-cell function being glucose-stimulated insulin secretion (GSIS). Reactive oxygen species (ROS) derived from glucose metabolism serve as one of the metabolic signals for GSIS. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a central transcription factor regulating cellular adaptive response to oxidative stress.<br /><br /> We tested the hypothesis that activation of Nrf2 and induction of antioxidant enzymes in response to arsenic exposure impedes glucose-triggered ROS signaling and thus GSIS.<br /><br /> Exposure of INS-1(832/13) cells to low levels of arsenite led to decreased GSIS in a dose- and time-dependent fashion. Consistent with our hypothesis, a significantly enhanced Nrf2 activity, determined by its nuclear accumulation and induction of its target genes, was observed in arsenite-exposed cells. In keeping with the activation of Nrf2-mediated antioxidant response, intracellular glutathione and intracellular hydrogen peroxide-scavenging activity was dose dependently increased by arsenite exposure. Although the basal cellular peroxide level was significantly enhanced, the net percentage increase in glucose-stimulated intracellular peroxide production was markedly inhibited in arsenite-exposed cells. In contrast, insulin synthesis and the consensus GSIS pathway, including glucose transport and metabolism, were not significantly reduced by arsenite exposure.<br /><br /> Our studies suggest that low levels of arsenic provoke a cellular adaptive oxidative stress response that increases antioxidant levels, dampens ROS signaling involved in GSIS, and thus disturbs beta-cell function.",
Arsenic,2088482,"Serum trace metal levels in Alzheimer's disease and normal control groups Abstract: Objective: To determine whether serum trace metals are related to abnormal cognition in Alzheimer’s disease (AD). Methods: We studied serum lead (Pb), cadmium (Cd), mercury (Hg), and arsenic(As) in 89 patients with AD and in 118 cognitively normal individuals. We analyzed the results of the blood tests and the food intake. Results: Serum Pb levels correlated with word list recall (P = .039) and word list recognition (P = .037). Without age adjustment, serum Cd levels (P = .044) were significantly higher in the AD group. After stratified age adjustment, the levels of selected trace metals did not differ significantly between AD and normal individuals. Food intakes regarding selected trace metals were not significantly different between the 2 groups. Conclusions: In this study, serum Pb, Cd, Hg, and As levels were not directly related to abnormal cognition in AD. Serum Pb levels were significantly negatively correlated with verbal memory scores.",
Arsenic,1018931,"Sodium arsenite enhances AP-1 and NFkappaB DNA binding and induces stress protein expression in precision-cut rat lung slices Abstract: Arsenic is a known human carcinogen. These studies were designed to examine the impact of low arsenite concentrations on immediate early gene expression in precision-cut rat lung slices. Precision-cut lung slices are a versatile in-vitro system for toxicity studies, as they preserve the architecture and cellular heterogeneity of the lung. Since 0.1-100 microM arsenite did not compromise slice viability at 4 hours, effects of arsenite on the expression of c-jun/AP-1, NFkappaB, HSP 32, HSP 72, HSP 60, and HSP 90 were studied, using these concentrations of arsenite at 4 h. Nuclear c-jun was increased by 10 and 100 microM arsenite, while NFkappaB was not affected. Gel-shift assays indicated that 10 microM arsenite resulted in an enhanced DNA-binding activity of both AP-1 and NFkappaB. Confocal microscopic analysis of AP-1 indicated nuclear localization of this transcription factor, mainly in type-II epithelial cells and alveolar macrophages. Nuclear localization of NFkappaB was lower than that observed for AP-1, while most of the NFkappaB was localized to cytoplasm of type-II epithelial cells and alveolar macrophages. HSP 32 was increased by 1.0 and 10 microM arsenite, while HSP 72 was increased by only 100 microM arsenite. HSP 60 and HSP 90 were not changed by arsenite. These studies indicate that noncytotoxic concentrations of arsenite are capable of affecting signal transduction pathways and gene expression in the lung.",
Arsenic,17057,"Tyrosine phosphatases as targets in metal-induced signaling in human airway epithelial cells Abstract: We previously showed that exposure to metal-laden combustion particles disregulates protein tyrosine phosphate homeostasis in human airway epithelial cells (HAEC). More recently, we reported that exposure to certain metal ions activates mitogen-activated protein kinases in HAEC. To study the mechanism responsible, we examined the effects of arsenic (As), vanadium (V), and zinc (Zn) on tyrosine phosphate catabolism in BEAS S6 cells or cultured human bronchial epithelial cells. Western blots and immunocytochemical analyses showed that exposure to noncytotoxic levels of As, V, or Zn resulted in increased levels of protein phosphotyrosines in HAEC. Tyrosine phosphatase activity, measured against [32P]-labeled PolyGlu:Tyr, was markedly inhibited in cells treated with V or Zn but was unaffected by exposure to As. Fast performance liquid chromatography fractionation and subsequent in-gel phosphatase activity assay of HAEC protein extracts revealed the presence of numerous tyrosine phosphatases, of varying molecular weights, that were effectively inhibited by exposure to V or Zn ions. As had no discernible effect on these enzymes. The protein tyrosine phosphatase PTP1B, immunoprecipitated from HAEC, was similarly inhibited by V and Zn but not by As ions. These data show that V and Zn may induce tyrosine phosphate accumulation by inhibiting dephosphorylation and implicate kinase activation as the mechanism in HAEC exposed to As. These findings suggest that metal exposure can activate signaling pathways through multiple mechanisms.",
Arsenic,628120,"Use of the fluorescent micronucleus assay to detect the genotoxic effects of radiation and arsenic exposure in exfoliated human epithelial cells Abstract: The exfoliated cell micronucleus (MN) assay using fluorescent in situ hybridization (FISH) with a centromeric probe is a rapid method for determining the mechanism of MN formation in epithelial tissues exposed to carcinogenic agents. Here, we describe the use of this assay to detect the presence or absence of centromeric DNA in MN induced in vivo by radiation therapy and chronic arsenic (As) ingestion. We examined the buccal cells of an individual receiving 6,500 rads of photon radiation to the head and neck. Exfoliated cells were collected before, during, and after treatment. After radiation exposure a 16.6-fold increase in buccal cell MN frequency was seen. All induced MN were centromere negative (MN-) resulting from chromosome breakage. This finding is consistent with the clastogenic action of radiation and confirmed the reliability of the method. Three weeks post-therapy, MN frequencies returned to baseline. We also applied the assay to exfoliated bladder cells of 18 people chronically exposed to high levels of inorganic arsenic (In-As) in drinking water (average level, 1,312 micrograms As/L) and 18 matched controls (average level, 16 micrograms As/L). The combined increase in MN frequency was 1.8-fold (P = 0.001, Fisher's exact test). Frequencies of micronuclei containing acentric fragments (MN-) and those containing whole chromosomes (MN+) both increased (1.65-fold, P = 0.07, and 1.37-fold, P = 0.15, respectively), suggesting that arsenic may have both clastogenic and weak aneuploidogenic properties in vivo. After stratification on sex, the effect was stronger in male than in female bladder cells. In males the MN- frequency increased 2.06-fold (P = 0.07) while the frequency of MN+ increased 1.86-fold (P = 0.08). In addition, the frequencies of MN- and MN+ were positively associated with urinary arsenic and its metabolites. However, the association was stronger for micronuclei containing acentric fragments. By using FISH with centromeric probes, the mechanism of chemically induced genotoxicity can now be determined in epithelial tissues.",
Arsenic,1348203,Arsenic hyperaccumulation and localization in the pinnule and stipe tissues of the gold-dust fern (Pityrogramma calomelanos (L.) Link var. austroamericana (Domin) Farw.) using quantitative micro-PIXE spectroscopy Abstract: ,
Arsenic,627208,"Effects of protein deficient diets on the developmental toxicity of inorganic arsenic in mice Abstract: Inorganic arsenic, when given by injection to pregnant laboratory animals (mice, rats, hamsters), has been shown to induce malformations. Arsenic methylation may be a detoxification step, and diets deficient in protein are a poor source of methyl donors and may possibly result in impaired arsenic methylation. Human health effects from chronic arsenic exposure have been reported mainly in populations with low socioeconomic status. Individuals in such populations are likely to suffer from malnutrition, which can compromise embryonic/fetal development and diminish arsenic methylating capacity. We sought to determine if dietary protein deficiency affects the developmental toxicity of inorganic arsenic.<br /><br /> Mated females were randomly assigned to one of 12 treatment groups. Experimental groups received either AsIII or AsV i.p. on Gestation Day 8 (GD 8, plug=GD 0) and were maintained on a 5%, 10%, or 20% protein custom mixed diet from GD 1 until sacrifice. Controls received the custom diets alone, were given AsIII or AsV i.p. on GD 8 with Teklad LM-485 rodent diet, or were fed the LM-485 diet alone. Test females were sacrificed on GD 17, and their litters were examined for mortality and developmental defects.<br /><br /> Arsenic plus dietary protein deficiency decreased maternal weight gain and increased the incidences of exencephaly, ablepharia, and skeletal defects, such as malformed vertebral centra, fused ribs, and abnormal sternebrae (bipartite, rudimentary, or unossified).<br /><br /> These results demonstrate that dietary protein deficiency enhances the developmental toxicity of inorganic arsenic, possibly by impairment of arsenic methylation.",
Arsenic,1017550,"Kindlin-2 expression in arsenite- and cadmium-transformed bladder cancer cell lines and in archival specimens of human bladder cancer Abstract: <strong>OBJECTIVE: </strong>To confirm a microarray study that suggested that Kindlin-2 might play a role in the development and progression of bladder cancer. There has been no previous examination of Kindlin-2 expression in human bladder cancer.<br /><br /><strong>METHODS: </strong>A combination of real-time polymerase chain reaction, Western analysis, and immunohistochemistry was used to characterize Kindlin-2 expression in arsenite (As(+3))- and cadmium (Cd(+2))-transformed human cell lines, their tumor transplants in immunocompromised mice, and in archival specimens of human bladder and bladder cancer.<br /><br /><strong>RESULTS: </strong>The results show that the Kindlin-2 expression patterns in the cell lines were not duplicated in the tumor tissues. However, it was shown that Kindlin-2 was expressed in the stromal element of all the transplanted tumors and archival specimens of human bladder cancer. It was also shown that a small number of high-grade invasive urothelial cancers have focal expression of Kindlin-2 in the tumor cells.<br /><br /><strong>CONCLUSION: </strong>Kindlin-2 is expressed in the stromal component of most, if not all, human bladder cancers. Kindlin-2 is not expressed in normal urothelium. Kindlin-2 is expressed in a small subset of high-grade invasive bladder cancers and may have potential as a prognostic marker for tumor progression.",
Arsenic,627122,"Exposure of mice to arsenic and/or benzo[a]pyrene does not increase the frequency of Aprt-deficient cells recovered from explanted skin of Aprt heterozygous mice Abstract: Exposure to inorganic arsenic in drinking water is linked to cancer in humans, but the mechanism of arsenic-induced cancer is not clear. Arsenic is not a powerful point mutagen, but can cause chromosome malsegregation and mitotic recombination, two events that can cause loss of tumor suppressor alleles and thereby contribute to the evolution of cancerous cells. To determine whether arsenic increases the frequency of allele loss due to either malsegregation or mitotic recombination in vivo, Aprt(+/-) hybrid mice were exposed to sodium arsenite (10 mg/L) in their drinking water for 10 weeks. To determine whether arsenic enhances the action of a known mutagen, half of the arsenic-treated mice were exposed to benzo[a]pyrene (BaP) for 8 weeks by skin painting (500 nmoles/week). Cells were taken from painted dorsal skin and cultured in the presence of 2,6-diaminopurine (DAP), to select colonies lacking adenosine phosphoribosyl transferase (Aprt) activity. The frequency of DAP-resistant (DAP(r)) colonies varied substantially within the treatment groups, but there was no significant difference between the groups. Analysis of DNA from DAP(r) colonies suggested that mitotic recombination contributed to the loss of wild-type Aprt allele. Whether arsenic or BaP enhanced or diminished the frequency of this process could not be deduced from these data.",
Arsenic,1021561,"Physiological effects of arsenate on transplant thalli of the lichen Pyxine cocoes (Sw.) Nyl Abstract: Introduction The changes in photosynthetic pigments, chlorophyll fluorescence, protein content, and antioxidant enzymes were investigated in a foliose lichen Pyxine cocoes, which was subjected to increasing concentrations of arsenate. Methods The arsenate concentrations of 10, 25, 50, 75, 100, and 200 ?M were sprayed every alternate day on the lichen thallus. The thalli were then harvested on 10, 20, 30, and 45 days. Results The quantity of photosynthetic pigments exhibited a decreasing trend till 20 days but increased from 30 days onwards. Concomitantly, chlorophyll fluorescence also showed a decreasing trend with increasing arsenic treatment duration as well as concentration. The higher concentration of arsenate was found to be deleterious to the photosynthesis of lichen as the chlorophyll fluorescence and the amount of pigments decreased significantly. The protein content of lichen increased uninterruptedly as the concentration of arsenate as well as duration of treatment increased. The activities of superoxide dismutase and ascorbate peroxide increased initially at lower concentration of arsenate but declined at higher concentrations and longer duration of treatment. Conclusions The catalase activity was found to be most susceptible to arsenate stress as its activity started declining from very beginning of the experiment. P. cocoes also proved to be an excellent accumulator of arsenate whose concentration increased in the thallus corresponding to its increase in the treatment and duration. Thus, it can be utilized for active biomonitoring of arsenic pollution.",
Arsenic,1070344,"Evaluating of arsenic(V) removal from water by weak-base anion exchange adsorbents Abstract: Arsenic contamination of groundwater has been called the largest mass poisoning calamity in human history and creates severe health problems. The effective adsorbents are imperative in response to the widespread removal of toxic arsenic exposure through drinking water. Evaluation of arsenic(V) removal from water by weak-base anion exchange adsorbents was studied in this paper, aiming at the determination of the effects of pH, competing anions, and feed flow rates to improvement on remediation. Two types of weak-base adsorbents were used to evaluate arsenic(V) removal efficiency both in batch and column approaches. Anion selectivity was determined by both adsorbents in batch method as equilibrium As(V) adsorption capacities. Column studies were performed in fixed-bed experiments using both adsorbent packed columns, and kinetic performance was dependent on the feed flow rate and competing anions. The weak-base adsorbents clarified that these are selective to arsenic(V) over competition of chloride, nitrate, and sulfate anions. The solution pH played an important role in arsenic(V) removal, and a higher pH can cause lower adsorption capacities. A low concentration level of arsenic(V) was also removed by these adsorbents even at a high flow rate of 250-350 h(-1). Adsorbed arsenic(V) was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for the next adsorption operation after rinsing with water. The weak-base anion exchange adsorbents are to be an effective means to remove arsenic(V) from drinking water. The fast adsorption rate and the excellent adsorption capacity in the neutral pH range will render this removal technique attractive in practical use in chemical industry.",
Arsenic,1508727,"Deterioration of horizontal saccades in progressive supranuclear palsy Abstract: <strong>OBJECTIVE: </strong>To investigate horizontal saccade changes according to disease stage in patients with progressive supranuclear palsy (PSP).<br /><br /><strong>METHODS: </strong>We studied visually and memory guided saccades (VGS and MGS) in 36 PSP patients at various disease stages, and compared results with those in 66 Parkinson's disease (PD) patients and 58 age-matched normal controls.<br /><br /><strong>RESULTS: </strong>Both vertical and horizontal saccades were affected in PSP patients, usually manifesting as &quot;slow saccades&quot; but sometimes as a sequence of small amplitude saccades with relatively well preserved velocities. Disease progression caused saccade amplitude reduction in PSP but not PD patients. In contrast, VGS and MGS latencies were comparable between PSP and PD patients, as were the frequencies of saccades to cue, suggesting that voluntary initiation and inhibitory control of saccades are similar in both disorders. Hypermetria was rarely observed in PSP patients with cerebellar ataxia (PSPc patients).<br /><br /><strong>CONCLUSIONS: </strong>The progressively reduced accuracy of horizontal saccades in PSP suggests a brainstem oculomotor pathology that includes the superior colliculus and/or paramedian pontine reticular formation. In contrast, the functioning of the oculomotor system above the brainstem was similar between PSP and PD patients.<br /><br /><strong>SIGNIFICANCE: </strong>These findings may reflect a brainstem oculomotor pathology.",
Arsenic,1508724,"The role of salivary duct morphology in the aetiology of sialadenitis: Statistical analysis of sialographic features Abstract: Morphologic characteristics of salivary ducts may contribute to stagnation of saliva. The authors hypothesized that some features might contribute to development of submandibular and parotid sialadenitis. 106 digital subtraction sialograms (DSS) were retrospectively reviewed for: degree of sialadenitis, length of Wharton's and Stensen's ducts (SD), and angle of Wharton's duct (WD) genu. Student's t test was used for independent samples to statistically compare normal and sialadenitis groups. The effect of independent variables (age, gender, side, degree of sialadenitis) on the dependent variable (length or angle) were tested using regression analysis. Submandibular duct sialadenitis was mild (67%), moderate (8%), or severe (25%); parotid duct sialadenitis was mild (57%), moderate (18%), or severe (25%). Mean length of normal WD was 58.2 mm, and 56.3 mm with sialadenitis. Mean length of normal SD was 52 mm, and 53 mm with sialadenitis. The mean angle of WD genu was 115° in normal ducts, and 119° with sialadenitis. None of the independent variables affected variation in length or angle. There were no statistical differences in duct length or measured angle between normal and sialadenitis groups. There is a wide variation in salivary duct morphology but this does not appear to be associated with the cause of sialadenitis.",
Arsenic,2064182,"Role of nitric oxide molecule in the tolerance to arsenic in plants: signal or antioxidant? Abstract: Effect of nitric oxide (NO) in mitigating stress induced by arsenic (As) was assessed in Pistia stratiotes, with NO supplied in the form of SNP. Plants were exposed to four treatments: control, SNP (0.1 mg L-1), As (1.5 mg L-1) and As + SNP (1.5 and 0.1 mg L-1, respectively), for 24 h. The absorption of As triggered various changes, as the increased production of reactive oxygen intermediates and the damage to cell membranes. These effects were attenuated by SNP, which participated directly as an antioxidant, eliminating the superoxide anion, and as signaling, inducing an increase in the concentration of antioxidant enzymatic.",
Arsenic,1240202,"Arsenic induced oxidative stress in plants Abstract: Arsenic is a highly toxic metalloid for all forms of life including plants. Arsenic enters in the plants through phosphate transporters as a phosphate analogue or through aquaglycoporins. Uptake of arsenic in plant tissues adversely affects the plant metabolism and leads to various physiological and structural disorders. Photosynthetic apparatus, cell division machinery, energy production, and redox status are the major section of plant system that are badly affected by As (V). Similarly As (III) can react with thiol (-SH) groups of enzymes and inhibits various metabolic processes. Arsenic is also known to induce oxidative stress directly by generating reactive oxygen species (ROS) during conversion of its valence forms or indirectly by inactivating antioxidant molecules through binding with their -SH groups. As-mediated oxidative stress causes cellular, molecular and physiological disturbances in various plant species. Activation of enzymatic antioxidants namely, superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR), Glutathione s-transferase, glutathione peroxidase (GPX) as well as non antioxidant compounds such as, ascorbate, glutathione, carotenoids are reported to neutralize arsenic mediated oxidative stress. Understanding of biochemistry of arsenic toxicity would be beneficial for the development of arsenic tolerant crops and other economically important plants.",
Arsenic,737350,"The consequences of chronic arsenic poisoning among Moselle wine growers. Pathoanatomical investigations of post-mortem examinations performed between 1960 and 1977 Abstract: From post-mortem examinations performed at the Pathology Institute at Koblenz, 163 cases of wine growers affected by chronic arsenic poisoning were analyzed. While a reduction could be seen in the number of cases of liver cirrhosis, the carcinoma rate was still high and even increased when compared to earlier reports. Lung cancers were identified in 66% of all wine growers affected and are thus the leading form of the skin were observed. A particular characteristic of amount of carcinomas or precarcinogenic alterations of arsenic carcinoma. However, nearly the same amount of carcinomas or precarcinogenic alterations of the skin were observed. A particular characteristic of cases. Among the multiple tumors, up to six different carcinomas were found. As arsenic is no longer detectable by toxicologic-chemical means the deposits of arsenic have been depleted and excreted long ago and so the diagnosis of chronic poisoning today depends on morphological changes of the skin (arsenic hyperkeratosis, melanosis and M. Bowen) which have been shown to be reliable. A comparison of our analysis with much more extensive material collected by the trade association supports our experience and the determined case rates. Furthermore modern theories on the carcinogenic action of arsenic, the question of the tumor latency and the relation of specific cancers to the poison are presented. In addition medical opinions on chronic arsenic poisoning are discussed.",
Arsenic,1340518,"Chemical activation of a high-affinity glutamate transporter in human erythrocytes and its implications for malaria-parasite-induced glutamate uptake Abstract: Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arsenite-induced L-glutamate influx was via a high-affinity, Na(+)-dependent system showing characteristics of members of the &quot;excitatory amino acid transporter&quot; (EAAT) family. Western blots and immunofluorescence assays revealed the presence of a member of this family, EAAT3, on the erythrocyte membrane. Erythrocytes infected with the malaria parasite Plasmodium falciparum take up glutamate from the extracellular environment. Although the majority of uptake is via a low-affinity Na(+)-independent pathway there is, in addition, a high-affinity uptake component, raising the possibility that the parasite activates the host cell glutamate transporter.",
Arsenic,1339165,"Influence of inoculation of arsenic-resistant Staphylococcus arlettae on growth and arsenic uptake in Brassica juncea (L.) Czern. Var. R-46 Abstract: An arsenic hypertolerant bacterium was isolated from arsenic contaminated site of West Bengal, India. The bacteria was identified as Staphylococcus arlettae strain NBRIEAG-6, based on 16S rDNA analysis. S. arlettae was able to remove arsenic from liquid media and possesses arsC gene, gene responsible for arsenate reductase activity. The biochemical profiling of the isolated strain showed that it had the capacity of producing indole acetic acid (IAA), siderophores and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. Furthermore, an experiment was conducted to test the effect of S. arlettae inoculation on concurrent plant growth promotion and arsenic uptake in Indian mustard plant [Brassica juncea (L.) Czern. Var. R-46] when grown in arsenic spiked (5, 10 and 15mgkg(-1)) soil. The microbial inoculation significantly (p&lt;0.05) increased biomass, protein, chlorophyll and carotenoids contents in test plant. Moreover, as compared to the non-inoculated control, the As concentration in shoot and root of inoculated plants were increased from 3.73 to 34.16% and 87.35 to 99.93%, respectively. The experimental results show that the plant growth promoting bacteria NBRIEAG-6 has the ability to help B. juncea to accumulate As maximally in plant root, and therefore it can be accounted as a new bacteria for As phytostabilization.",
Arsenic,1018181,"An emerging role for epigenetic dysregulation in arsenic toxicity and carcinogenesis Abstract: <strong>BACKGROUND: </strong>Exposure to arsenic, an established human carcinogen, through consumption of highly contaminated drinking water is a worldwide public health concern. Several mechanisms by which arsenical compounds induce tumorigenesis have been proposed, including oxidative stress, genotoxic damage, and chromosomal abnormalities. Recent studies have suggested that epigenetic mechanisms may also mediate toxicity and carcinogenicity resulting from arsenic exposure.<br /><br /><strong>OBJECTIVE: </strong>We examined the evidence supporting the roles of the three major epigenetic mechanisms-DNA methylation, histone modification, and microRNA (miRNA) expression-in arsenic toxicity and, in particular, carcinogenicity. We also investigated future research directions necessary to clarify epigenetic and other mechanisms in humans.<br /><br /><strong>DATA SOURCES AND SYNTHESIS: </strong>We conducted a PubMed search of arsenic exposure and epigenetic modification through April 2010 and summarized the in vitro and in vivo research findings, from both our group and others, on arsenic-associated epigenetic alteration and its potential role in toxicity and carcinogenicity.<br /><br /><strong>CONCLUSIONS: </strong>Arsenic exposure has been shown to alter methylation levels of both global DNA and gene promoters; histone acetylation, methylation, and phosphorylation; and miRNA expression, in studies analyzing mainly a limited number of epigenetic end points. Systematic epigenomic studies in human populations exposed to arsenic or in patients with arsenic-associated cancer have not yet been performed. Such studies would help to elucidate the relationship between arsenic exposure, epigenetic dysregulation, and carcinogenesis and are becoming feasible because of recent technological advancements.",1
Arsenic,1337278,"Arsenic effect on the model crop symbiosis Bradyrhizobium-soybean Abstract: Soybean (Glycine max) is often being cultivated in soils with moderate to high arsenic (As) concentrations or under irrigation with As contaminated groundwater. The purpose of this study was to determine the effect of As on soybean germination, development and nodulation in soybean-Bradyrhizobium japonicum E109 symbiosis, as a first-step approach to evaluate the impact of As on soybean production. Semi-hydroponic assays were conducted using soybean seedlings inoculated and non-inoculated with B. japonicum E109 and treated with arsenate or arsenite. Soybean germination and development, at early stage of growth, were significantly reduced from 10 ?M arsenate or arsenite. This also was seen for soybean seedlings inoculated with B. japonicum mainly with arsenite where, in addition, the number of effective nodules was reduced, despite that the microorganism tolerated the metalloid. This minor nodulation could be due to a reduced motility (swarming and swimming) of the microorganism in presence of As. Arsenic concentration in roots was about 250-times higher than in shoots. Transference coefficient values indicated that As translocation to aerial parts was low and As accumulated mainly in roots, without significant differences between inoculated and non-inoculated plants. The presence of As restricted soybean-B. japonicum symbiosis and hence, the efficiency of most used commercial inoculants for soybean. Thus, water and/or soils containing As would negatively impact on soybean production, even in plants inoculated with B. japonicum E109.",
Arsenic,1344851,"p27 suppresses arsenite-induced Hsp27/Hsp70 expression through inhibiting JNK2/c-Jun- and HSF-1-dependent pathways Abstract: p27 is an atypical tumor suppressor that can regulate the activity of cyclin-dependent kinases and G(0)-to-S phase transitions. More recent studies reveal that p27 may also exhibit its tumor-suppressive function through regulating many other essential cellular events. However, the molecular mechanisms underlying these anticancer effects of p27 are largely unknown. In this study, we found that depletion of p27 expression by either gene knock-out or knockdown approaches resulted in up-regulation of both Hsp27 and Hsp70 expression at mRNA- and promoter-derived transcription as well as protein levels upon arsenite exposure, indicating that p27 provides a negative signal for regulating the expression of Hsp27 and Hsp70. Consistently, arsenite-induced activation of JNK2/c-Jun and HSF-1 pathways was also markedly elevated in p27 knock-out (p27(-/-)) and knockdown (p27 shRNA) cells. Moreover, interference with the expression or function of JNK2, c-Jun, and HSF-1, but not JNK1, led to dramatic inhibition of arsenite-induced Hsp27 and Hsp70 expression. Collectively, our results demonstrate that p27 suppresses Hsp27 and Hsp70 expression at the transcriptional level specifically through JNK2/c-Jun- and HSF-1-dependent pathways upon arsenite exposure, which provides additional important molecular mechanisms for the tumor-suppressive function of p27.",
Arsenic,1022071,"The relationship between blood mercury level and osteoporosis in postmenopausal women Abstract: OBJECTIVE: Postmenopausal women have a higher prevalence of osteoporosis compared with premenopausal women. Postmenopause status has been found to be an independent risk factor for osteoporosis. Several studies have reported that heavy metals, including lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As), have detrimental effects on bone. The aim of this study was to evaluate the association among heavy metals, including Pb, Hg, Cd, and As, bone mineral density, and osteoporosis in postmenopausal Korean women. METHODS: We conducted a cross-sectional study of 481 postmenopausal women, all of whom were enrolled in the Korean National Health and Nutrition Examination Survey in 2008. Bone mineral density was measured using dual-energy x-ray absorptiometry. Blood Pb, Hg, and Cd and urinary As levels were measured. RESULTS: Postmenopausal women with higher blood Hg levels were more likely to be younger and have higher vitamin D levels, fish consumption, and prevalence of osteoporosis. On multivariate logistic regression analysis, postmenopausal women with blood Hg levels in the fourth quartile had a 0.36-fold decreased risk of having osteoporosis compared with those with levels in the first quartile, after adjustments for age, body mass index, alcohol intake, smoking history, exercise, use of oral contraceptive pills, hormone therapy, intake of caloric energy and calcium, fish consumption, and vitamin D level. However, there was no association between other heavy metals and osteoporosis. CONCLUSIONS: High blood Hg levels were associated with a lower risk of having osteoporosis in postmenopausal women. Because biomarkers of all four metals measured in this study reflect recent exposures, further studies are necessary to clarify the association of osteoporosis with the level of heavy metals in biomarkers for long-term exposure such as hair or fingernail.",
Arsenic,710860,"Arsenite suppresses Notch1 signaling in human keratinocytes Abstract: Arsenic is a well-known human skin carcinogen whose mechanism of action remains to be elucidated. In this work using cultured human epidermal cells, arsenite suppressed accumulation of the transcriptionally active intracellular domain of Notch1. The cells responded to an active peptide from the Notch1 ligand, Jagged1, with increased levels of differentiation marker mRNAs and decreased colony-forming ability. Arsenite suppressed Jagged1 effects and expression of Jagged1 mRNA as well. Moreover, exposure of the cells to a gamma-secretase inhibitor prevented Notch1 processing, decreased cell size and differentiation marker expression, and increased proliferative potential, all effects that occur with arsenite treatment. Thus, arsenite action in suppressing keratinocyte differentiation while maintaining germinative capability could be due to inhibition of Notch1 signaling subsequent to ligand binding. This work also revealed that such arsenite action depends upon epidermal growth factor receptor kinase activity. These findings may help to explain how arsenite, by decreasing generation of the tumor suppressor Notch1, contributes to skin carcinogenesis.",
Arsenic,1015731,"Exposure to Low Level of Arsenic and Lead in Drinking Water from Antofagasta City Induces Gender Differences in Glucose Homeostasis in Rats Abstract: Populations chronically exposed to arsenic in drinking water often have increased prevalence of diabetes mellitus. The purpose of this study was to compare the glucose homeostasis of male and female rats exposed to low levels of heavy metals in drinking water. Treated groups were Sprague-Dawley male and female rats exposed to drinking water from Antofagasta city, with total arsenic of 30 ppb and lead of 53 ppb for 3 months; control groups were exposed to purified water by reverse osmosis. The two treated groups in both males and females showed arsenic and lead in the hair of rats. The ?-aminolevulinic acid dehydratase was used as a sensitive biomarker of arsenic toxicity and lead. The activity of ?-aminolevulinic acid dehydratase was reduced only in treated male rats, compared to the control group. Treated males showed a significantly sustained increase in blood glucose and plasma insulin levels during oral glucose tolerance test compared to control group. The oral glucose tolerance test and the homeostasis model assessment of insulin resistance demonstrated that male rats were insulin resistant, and females remained sensitive to insulin after treatment. The total cholesterol and LDL cholesterol increased in treated male rats vs. the control, and triglyceride increased in treated female rats vs. the control. The activity of intestinal Na+/glucose cotransporter in male rats increased compared to female rats, suggesting a significant increase in intestinal glucose absorption. The findings indicate that exposure to low levels of arsenic and lead in drinking water could cause gender differences in insulin resistance.",
Arsenic,1031073,"Chronic effects of arsenic on American red crayfish, Procambarus clarkii, exposed to monosodium methanearsonate (MSMA) herbicide Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM ENVIRONMENTAL TOXICOLOGY WATER POLLUTION SHELLFISH FOOD RESIDUE",
Arsenic,1797800,"Dicopper(II) Metallacyclophanes with Electroswitchable Polymethyl-Substituted para-Phenylene Spacers Abstract: Double-stranded anionic dinuclear copper(II) metallacyclic complexes of the paracyclophane type [Cu2 L2 ](4-) have been prepared by the Cu(II) -mediated self-assembly of different para-phenylenebis(oxamato) bridging ligands with either zero-, one-, or four-electron-donating methyl substituents (L=N,N'-para-phenylenebis(oxamate) (ppba; 1), 2-methyl- N,N'-para-phenylenebis(oxamate) (Meppba; 2), and 2,3,5,6-tetramethyl- N,N'-para-phenylenebis(oxamate) (Me4 ppba; 3)). These complexes have been isolated as their tetra-n-butylammonium (1?a-3?a), lithium(I) (1?b-3?b), and tetraphenylphosphonium salts (1?c-3?c). The X-ray crystal structures of 1?a and 3?c show a parallel-displaced ?-stacked conformation with a smaller deviation from perpendicularity between the two benzene rings and the basal planes of the square planar Cu(II) ions when increasing the number of methyl substituents (average dihedral angles (?) of 58.72(7) and 73.67(5)° for 1?a and 3?c, respectively). Variable-temperature (2.0-300?K) magnetic-susceptibility measurements show an overall increase of the intramolecular antiferromagnetic coupling with the number of methyl substituents onto the para-phenylene spacers (-J=75-95, 100-124, and 128-144?cm(-1) for 1?a-c, 2?a-c, and 3?a-c, respectively; H=-JS1 ×S2 ). Cyclic voltammetry (CV) measurements show a reversible one-electron oxidation of the double polymethyl-substituted para-phenylenediamidate bridging skeleton at a relatively low formal potential that decreases with the number of methyl substituents (E1 =+0.33, +0.24, and +0.15?V vs. SCE for 1-3, respectively). The monooxidized dicopper(II) ?-radical cation species 3' prepared by the chemical oxidation of 3 with bromine exhibits intense metal-to-ligand charge-transfer (MLCT) transitions in the visible and near-IR (?max =595 and 875?nm, respectively) regions together with a rhombic EPR signal with a seven-line splitting pattern due to hyperfine coupling with the nuclear spin of the two Cu(II) ions. Density functional (DF) calculations for 3' evidence a characteristic iminoquinonoid-type short-long-short alternating sequence of C?N and C?C bonds for both tetramethyl-para-phenylenediamidate bridges and a large amount of spin density of negative sign mainly delocalized along each of the four benzene C atoms directly attached to the amidate N atoms, which is in agreement with a fully delocalized ?-stacked monoradical ligand description. Hence, the spins of the two Cu(II) ions (SCu =1/2) that are antiparallel aligned in 3 (OFF state) become parallel in 3' (ON state). Further developments may be then envisaged for this new permethylated dicopper(II) paracyclophane with a redox noninnocent ligand as a prototype for molecular magnetic electroswitch.",
Arsenic,1360575,"SPOT TESTS FOR THE DETECTION OF BOUND ARSENIC AND ANTIMONY Abstract: HAPAB Spot tests based upon the pyrolytic reaction of bound arsenic and antimony with ammonium bromide are described. Two tests for bound arsenic are given: Arsenic and antimony present in both inorganic and organic compounds in either the trivalent or pentavalent state are pyrolyzed with ammonium bromide, and the resulting arsenic ( III ) can be detected by the Bettendorf test. The second test for arsenic involves conversion to sulfides by exposure to hydrogen sulfide. The arsenic ( III ) sulfide then reacts with mercury ( II ) ion to form an immediate black precipitate. ANALYSIS 67/04/00, 51 1967",
Arsenic,2347666,"Diversity change of microbial communities responding to zinc and arsenic pollution in a river of northeastern China Abstract: Pollution discharge disturbs the natural functions of water systems. The environmental microbial community composition and diversity are sensitive key indicators to the impact of water pollutant on the microbial ecology system over time. It is meaningful to develop a way to identify the microbial diversity related to heavy metal effects in evaluating river pollution. Water and sediment samples were collected from eight sections along the Tiaozi River where wastewater and sewage were discharged from Siping City in northeastern China. The main pollutants contents and microbial communities were analyzed. As the primary metal pollutants, zinc (Zn) and arsenic (As) were recorded at the maximum concentrations of 420 and 5.72 ?g/L in the water, and 1704 and 1.92 mg/kg in the sediment, respectively. These pollutants posed a threat to the microbial community diversity as only a few species of bacteria and eukaryotes with strong resistance were detected through denaturing gradient gel electrophoresis (DGGE). Acinetobacter johnsonii, Clostridium cellulovorans, and Trichococcus pasteurii were the dominant bacteria in the severely polluted areas. The massive reproduction of Limnodrilus hoffmeisteri almost depleted the dissolved oxygen (DO) and resulted in the decline of the aerobic bacteria. It was noted that the pollution reduced the microbial diversity but the L. hoffmeisteri mass increased as the dominant community, which led to the overconsuming of DO and anaerobic stinking water bodies. Water quality, concentrations of heavy metals, and the spatial distribution of microbial populations have obvious consistencies, which mean that the heavy metals in the river pose a serious stress on the microorganisms.",
Arsenic,1508709,"Gender differences in mitral valve surgery Abstract: Background Knowledge regarding gender-specific mitral valve (MV) pathology and postoperative outcome is rare. We herein describe a single-center experience focusing on gender differences in MV surgery.Materials and Methods A total of 3,761 patients underwent minimal invasive MV surgery at our institution between 1999 and 2011. Demographic data, pre-, intra-, and postoperative characteristics have been collected, including details on MV pathology and surgical technique. Patient data have been analyzed with consideration of gender-specific differences.Results The cohort consisted of 2,124 male (56.5%; 58.8?±?12.5 years) and 1,637 female (43.5%; 64.5?±?13 years) patients. Mitral regurgitation was observed equally in women (91.3%) and men (92.4%). Additional MV stenosis has been diagnosed in 2.7% of men but in 13.9% of women (p?&lt;?0.001). Calcification of the posterior MV leaflet showed a similar trend: 20.1% in women compared with 6.5% in men. Prolapse of the posterior leaflet was present predominantly in men with 63.1 versus 35.7% in women (p?&lt;?0.001). Distinct MV repair differences were retrospectively detected between genders: posterior mitral leaflet resection was performed in 17.9% of men versus 10.1% of women; posterior mitral leaflet chordae replacement was performed in 39.3% of men compared with 20.4% of women. Prosthetic MV replacement was necessary in 26.8% of women compared with only 10.7% of men. Concomitant tricuspid valve surgery was mostly performed in women (14.4 versus 8.2%). Male patients showed a significant better postoperative long-term survival than females, with 96, 89, and 72% compared with 92, 82, and 58% after 1, 5, and 10 years, respectively (p?&lt;?0.0001).Conclusion?Substantial gender-specific differences regarding MV pathology, operative strategy, and long-term outcome are present that need to be addressed in clinical practice.",
Arsenic,628240,"The toxicity of trimethylarsine: An urban myth Abstract: In environmental terms, the 19th century was the age of arsenic. The uses of this element are almost too numerous to mention--embalming, cosmetics, glass and gunshot manufacture, pyrotechnics, taxidermy, weed and rodent control, and particularly in medicine, both by prescription and self-medication. Arsenic was characterized as a ""therapeutic mule"". For centuries, it was used for murder being known in France as ""poudre de succession"" (inheritance powder); the name arsenic is essentially synonymous with poison. However, in areas such as the Austrian province of Styria, arsenic was eaten, as the oxide or sulfide, to give freshness and beauty to the skin, to enhance sexual potency and to improve breathing and stamina in mountain climbing.",
Arsenic,1356831,"shRNA-Mediated Silencing Of AS3MT Expression Modulates The Capacity Of HepG2 Cells To Methylate Inorganic Arsenic Abstract: Several methyltransferases have been linked to the oxidative methylation of inorganic arsenic (iAs) in mammalian cells. However, the relative contributions of these enzymes to the overall capacity of cells to methylate iAs have not been characterized. Arsenic (+3 oxidation state) methyltransferase (AS3MT) that is expressed in rat and human hepatocytes catalyzes all steps in this pathway, yielding mono-, di-, and trimethylated metabolites that contain arsenic in either +3 or +5 oxidation states. Here we used post-transcriptional suppression of AS3MT expression by a short hairpin RNA (shRNA) to examine its role in the metabolic transformation of iAs in human hepatic cells. Three target 21-nucleotide sequences were selected for human AS3MT mRNA (NCBI, NM_020682), using a BLOCK-iT RNAi Designer (Invitrogen). shRNA oligonucleotides designed for each of the target sequences (both sense and antisense) were cloned into a retroviral pSIREN-RetroQ expression vector (Clontech) that contains a puromycin resistance gene and the human U6 promoter. The three shRNA expression vectors, as well as an empty pSIREN-RetroQ vector were used to transduce human hepatocellular carcinoma (HepG2) cells. Four clonal HepG2 cell lines were established, including HepG2/shRNA/A, HepG2/shRNA/B, HepG2/shRNA/C, and HepG2/shRNA/empty. AS3MT mRNA and protein levels were analyzed in each cell lines using quantitative PCR and immunoblot analysis, respectively. Capacity to methylate iAs was examined in cells exposed to 73As-arsenite for 66 hours. The PCR profiles show that the silencing of AS3MT expression was most effective in HepG2/shRNA/A cells. The rate of iAs methylation was suppressed by 95% in clonal HepG2/shRNA/A cells as compared to parental HepG2 cells. These results suggest that AS3MT is the key enzyme in the pathway for methylation of iAs in human hepatic cells.",
Arsenic,1016505,"Reduced reactive oxygen species-generating capacity contributes to the enhanced cell growth of arsenic-transformed epithelial cells Abstract: Reactive oxygen species (ROS) have been implicated in the activation of protein kinases, DNA damage responses, and cell apoptosis. The details of how ROS regulate these intracellular biochemical and genetic processes remain to be fully understood. By establishing transformed bronchial epithelial cells through chronic low-dose arsenic treatment, we showed that the capacity of ROS generation induced by arsenic is substantially reduced in the transformed cells relative to the nontransformed cells. Such a reduction in ROS generation endows cells with premalignant features, including rapid growth, resistance to arsenic toxicity, and increased colony formation of the transformed cells. To validate these observations, the capability of ROS generation was restored in the transformed cells by treatment with inhibitors or siRNAs to silence the function of superoxide dismutase (SOD) or catalase and cell growth was determined following these treatments. Enhancement in ROS generation suppressed cell growth and colony formation of the transformed cells significantly. Despite the fact that the transformed cells showed a decreased expression of NF-kappaB signaling proteins IKKbeta and IKKgamma, the proteolytic processing p105 and p100 and NF-kappaB DNA binding activity were elevated in these cells. Increasing ROS generation by silencing SOD and catalase reduced the DNA binding activity of NF-kappaB in the transformed cells. Taken together, the transformed cells induced by arsenic exhibited a decrease in ROS generation, which is responsible for the enhanced cell growth and colony formation of the transformed cells, most likely through a sustained alternative activation of the NF-kappaB transcription factor.",
Arsenic,1381582,"Role of mitochondrial permeability transition pore in coated-platelet formation Abstract: <strong>OBJECTIVE: </strong>Coated-platelets are a subset of cells observed during costimulation of platelets with collagen and thrombin. Important characteristics of coated-platelets include retention of multiple alpha-granule proteins and expression of phosphatidylserine on the cell surface. The mitochondrial permeability transition pore (MPTP) is a key step in apoptosis and is suggested to be involved in some forms of platelet activation. The objective of this study was to examine the role of MPTP in the synthesis of coated-platelets.<br /><br /><strong>METHODS AND RESULTS: </strong>Flow cytometric analysis of coated-platelet production was used to examine the impact of pharmacological effectors of MPTP formation. Cyclosporin A, coenzyme Q, and bongkrekic acid all inhibit MPTP formation as well as production of coated-platelets. Phenylarsine oxide and diamide, both potentiators of MPTP formation, stimulate coated-platelet synthesis. Atractyloside, another inducer of MPTP formation, does not affect the percentage of coated-platelets synthesized; however, it does increase the level of phosphatidylserine exposed on the surface of coated-platelets.<br /><br /><strong>CONCLUSIONS: </strong>These findings indicate that MPTP formation is an integral event in the synthesis of coated-platelets. Although the exact function of the MPTP remains to be determined, these data support a growing body of evidence that apoptosis-associated events are vital components of the platelet activation process. Formation of coated-platelets involves a complex set of activation events initiated by dual agonist activation. The mitochondrial permeability transition pore (MPTP) is a key intermediate in apoptosis and has been suggested to impact platelet activation. This report demonstrates that MPTP formation is essential to production of coated-platelets.",
Arsenic,711034,"Sodium arsenite delays the differentiation of C2C12 mouse myoblast cells and alters methylation patterns on the transcription factor myogenin Abstract: Epidemiological studies have correlated arsenic exposure with cancer, skin diseases, and adverse developmental outcomes such as spontaneous abortions, neonatal mortality, low birth weight, and delays in the use of musculature. The current study used C2C12 mouse myoblast cells to examine whether low concentrations of arsenic could alter their differentiation into myotubes, indicating that arsenic can act as a developmental toxicant. Myoblast cells were exposed to 20 nM sodium arsenite, allowed to differentiate into myotubes, and expression of the muscle-specific transcription factor myogenin, along with the expression of tropomyosin, suppressor of cytokine signaling 3 (Socs3), prostaglandin I2 synthesis (Ptgis), and myocyte enhancer 2 (Mef2), was investigated using QPCR and immunofluorescence. Exposing C2C12 cells to 20 nM sodium arsenite delayed the differentiation process, as evidenced by a significant reduction in the number of multinucleated myotubes, a decrease in myogenin mRNA expression, and a decrease in the total number of nuclei expressing myogenin protein. The expression of mRNA involved in myotube formation, such as Ptgis and Mef2 mRNA, was also significantly reduced by 1.6-fold and 4-fold during differentiation. This was confirmed by immunofluorescence for Mef2, which showed a 2.6-fold reduction in nuclear translocation. Changes in methylation patterns in the promoter region of myogenin (-473 to +90) were examined by methylation-specific PCR and bisulfite genomic sequencing. Hypermethylated CpGs were found at -236 and -126 bp, whereas hypomethylated CpGs were found at -207 bp in arsenic-exposed cells. This study indicates that 20 nM sodium arsenite can alter myoblast differentiation by reducing the expression of the transcription factors myogenin and Mef2c, which is likely due to changes in promoter methylation patterns. The delay in muscle differentiation may lead to developmental abnormalities.",
Arsenic,1797827,"Determination and evaluation of the metals and metalloids in the Chapeu-de-couro (Echinodorus macrophyllus (Kunth) Micheli) Abstract: The Chapeu-de-couro (Echinodorus macrophyllus (Kunth) Micheli) is a native plant from Brazil, which has been mainly used in medicinal application being a potent antirheumatic and diuretic, in the production of soft drinks, and also in the ornamentation of aquariums. In this paper, the metals and metalloids for the leaves of chapeu-de-couro collected in the Paraguacu River from the city Cachoeira, Bahia State, Brazil, was determined and evaluated using multivariate analysis. The samples were digested using nitric acid and hydrogen peroxide and were analyzed using inductively coupled plasma mass spectrometry. The accuracy of the method was confirmed by analysis of a certified reference material of apple leaves, furnished by National Institute of Standard and Technology. The study involved 15 samples of the Paraguacu River. The results expressed as milligrams of element per kilogram of sample demonstrated that the concentration ranges varied: 1.39-5.27 for chromium, 44.85-165.39 for manganese, 0.55-0.84 for arsenic, 0.01-3.94 for antimony, and 0.18-0.31 for lead. The principal component analysis and hierarchical cluster analysis evidenced that the concentrations of the metals and metalloids varied according with the variations in the water of the Paraguacu.",
Arsenic,1355070,"Mechanisms involved in sodium arsenite-induced apoptosis of human neutrophils Abstract: Apoptosis is a distinct mechanism by which eukaryotic cells die. Factors governing the induction of polymorphonuclear leukocyte (PMN) apoptosis should be important in understanding resolution of acute inflammation. The mechanisms for induction of PMN apoptosis remain uncertain; however, oxidative stress has been suggested. The aims of this study were to determine whether reactive oxygen intermediates play a role in PMN apoptosis and to investigate inhibition of this process by selective use of antioxidants. PMN were isolated from 10 healthy volunteers. PMN (1 x 10(6) PMN/mL) were cultured in 40, 80, and 160 microM of arsenite for 2, 6, 12, 18, and 24 h. Apoptosis was assessed qualitatively by morphology and gel electrophoresis and quantitatively by CD16 receptor expression and propidium iodide DNA staining. There was a significant (P < 0.05) increase in the rate of apoptosis on incubation with arsenite (80 and 160 microM). To investigate the mechanism of this process, intracellular respiratory burst activity was measured following arsenite culture. We found that arsenite-induced PMN apoptosis correlated with an increase in intracellular respiratory burst. To further investigate the role of oxidative injury in inducing apoptosis, the antioxidants catalase, dimethyl sulfoxide (DMSO), glutathione (GSH), N-acetylcysteine (NAC), and taurine were investigated and we demonstrated that GSH, NAC, and taurine were significantly protective against arsenite-induced apoptosis. However, catalase and DMSO failed to induce protection. This study demonstrates that arsenite induces PMN apoptosis through an oxygen-dependent mechanism that can be prevented through selective antioxidants.",1
Arsenic,1033652,"Arsenic as a cause of skin cancer, with notes on its occurrence in Pretoria Abstract: ",
Arsenic,1797847,"Remodeling of Ago2-mRNA interactions upon cellular stress reflects miRNA complementarity and correlates with altered translation rates Abstract: When adapting to environmental stress, cells attenuate and reprogram their translational output. In part, these altered translation profiles are established through changes in the interactions between RNA-binding proteins and mRNAs. The Argonaute 2 (Ago2)/microRNA (miRNA) machinery has been shown to participate in stress-induced translational up-regulation of a particular mRNA, CAT-1; however, a detailed, transcriptome-wide understanding of the involvement of Ago2 in the process has been lacking. Here, we profiled the overall changes in Ago2-mRNA interactions upon arsenite stress by cross-linking immunoprecipitation (CLIP) followed by high-throughput sequencing (CLIP-seq). Ago2 displayed a significant remodeling of its transcript occupancy, with the majority of 3' untranslated region (UTR) and coding sequence (CDS) sites exhibiting stronger interaction. Interestingly, target sites that were destined for release from Ago2 upon stress were depleted in miRNA complementarity signatures, suggesting an alternative mode of interaction. To compare the changes in Ago2-binding patterns across transcripts with changes in their translational states, we measured mRNA profiles on ribosome/polysome gradients by RNA sequencing (RNA-seq). Increased Ago2 occupancy correlated with stronger repression of translation for those mRNAs, as evidenced by a shift toward lighter gradient fractions upon stress, while release of Ago2 was associated with the limited number of transcripts that remained translated. Taken together, these data point to a role for Ago2 and the mammalian miRNAs in mediating the translational component of the stress response.",
Arsenic,1387280,"Health survey of former workers in a Norwegian coke plant: Part 2. Cancer incidence and cause specific mortality Abstract: OBJECTIVES: A Norwegian coke plant that operated from 1964 to 1988 was investigated to ascertain whether the male workers in this plant had increased morbidities of cancer or increased mortality from specific causes, particularly associated with specific exposures at the coke plant. METHODS: Personal data on all the employees of the plant were obtained from the plant's archives. With additional data from the Norwegian Bureau of Statistics we identified 888 male former workers at the plant. Causes of death were obtained from the Norwegian Bureau of Statistics, and cancer diagnoses from the Norwegian Cancer Registry. The results were compared with national averages adjusted for age. Specific exposures were estimated with records of actual measurements done at the plant and interviews with former workers at the plant. RESULTS: A significant excess of stomach cancer (standardised incidence ratio (SIR) 2.22, 95% confidence interval (95% CI) 1.01 to 4.21) was found. Mortality from ischaemic heart disease and sudden death was positively associated with work in areas which entailed peak exposures to CO. When considering work in such areas the past 3 years before death, the association was significant (p = 0.01). The last result is based on only two deaths. CONCLUSIONS: Considering the short follow up time and the small size of the cohort the results should be interpreted with a certain caution. The positive results would justify a re-examination of the cohort at a later date.",
Arsenic,1936149,"Simultaneous stabilization of arsenic, lead, and copper in contaminated soil using mixed waste resources Abstract: ",
Arsenic,1019877,"Low-level arsenite causes accumulation of ubiquitinated proteins in rabbit renal cortical slices and HEK293 cells Abstract: Arsenic is a known human carcinogen that affects a variety of processes within the cell. In this study, the effects of environmentally relevant As(III) exposures on the ubiquitin (Ub)-proteasome pathway have been investigated. Low-level As(III) exposure (0.5 - 10 microM) causes an accumulation of high-molecular-weight ubiquitin protein conjugates in both precision-cut rabbit renal-cortical slices and human embryonic kidney (HEK) 293 cells. The As(III) doses that induced these molecular changes were subcytotoxic in both model systems. Doses of 10 microM As(III) decreased cellular activity of the 20S proteasome by 40 and 15% in slices and HEK293 cells, respectively. As(III) did not cause any notable difference in Ub-conjugating activity of rabbit renal slices or HEK293 cells. Since ubiquitination plays such a vital role in maintaining cellular homeostasis, this noticeable perturbation of cellular ubiquitination is likely to have a multitude of signaling effects within the cells and may contribute to the pathogenesis of low-level arsenic.",
Arsenic,1356712,"Gene Expression In Normal Human Keratinocytes Modulated By Trivalent Arsenicals Abstract: Arsenic exposure has been correlated with the development of several human cancers including those found in the skin, lung, liver, kidney and urinary bladder. Humans are generally exposed to inorganic forms of arsenic, which may be inhaled or ingested. Arsenic forms mono- and di-methylated metabolites in vivo. Both inorganic and methylated arsenicals are excreted in urine. Two of these methylated trivalent species, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII) have been shown in cell systems to be more cytotoxic and genotoxic than trivalent/pentavalent inorganic arsenic and pentavalent methylated forms. The roles arsenite, MMAIII and DMAIII may play in arsenic carcinogenesis are unknown. We chose normal human epidermal keratinocytes (NHEKs) as a model system to study the contributions of individual trivalent arsenicals to the mode of action of arsenic carcinogenesis. NHEKs are a good model for such studies as 1) trivalent arsenicals are readily absorbed but not metabolized to more methylated intermediates in these cells and 2) skin cells are a major target cell of arsenic carcinogenesis in vivo. The global gene expression profiles of NHEKs exposed for 24 h to non-cytotoxic concentrations of inorganic arsenic (sodium arsenite), MMAIII and DMAIII were studied using Affymetrix? GeneChip Human U133 Plus 2.0 arrays and Genespring? v.7.2 software. For each arsenical, significantly effected genes were modulated in a dose-dependent manner. Many of these altered genes were classified as stress response genes or involved in cell signaling and growth. In arsenite- treated cells, upregulated phase II response genes involved in detoxification were the dominant feature, which were not upregulated to the same extent by exposure to MMAIII or DMAIII. Each of the three arsenicals had a distinct expression profile, including some genes that may serve as biomarkers of exposure. Future studies include determining which signaling pathways are involved in trivalent arsenicalmediated changes in gene expression.",
Arsenic,1327343,"Heme-regulated inhibitor kinase-mediated phosphorylation of eukaryotic translation initiation factor 2 inhibits translation, induces stress granule formation, and mediates survival upon arsenite exposure Abstract: Exposure to arsenite inhibits protein synthesis and activates multiple stress signaling pathways. Although arsenite has diverse effects on cell metabolism, we demonstrated that phosphorylation of eukaryotic translation initiation factor 2 at Ser-51 on the alpha subunit was necessary to inhibit protein synthesis initiation in arsenite-treated cells and was essential for stress granule formation. Of the four protein kinases known to phosphorylate eukaryotic translation initiation factor 2alpha, only the heme-regulated inhibitor kinase (HRI) was required for the translational inhibition in response to arsenite treatment in mouse embryonic fibroblasts. In addition, HRI expression was required for stress granule formation and cellular survival after arsenite treatment. In vivo studies elucidated a fundamental requirement for HRI in murine survival upon acute arsenite exposure. The results demonstrated an essential role for HRI in mediating arsenite stress-induced phosphorylation of eukaryotic translation initiation factor 2alpha, inhibition of protein synthesis, stress granule formation, and survival.",
Arsenic,1029423,"Arsenic levels in wipe samples collected from play structures constructed with CCA-treated wood: Impact on exposure estimates Abstract: Lumber treated with chromated copper arsenate (CCA) has been used in residential outdoor wood structures and playgrounds. The U.S. EPA has conducted a probabilistic assessment of children's exposure to arsenic from CCA-treated structures using the Stochastic Human Exposure and Dose Simulation model for the wood preservative scenario (SHEDS-Wood). The EPA assessment relied on data from an experimental study using adult volunteers and designed to measure arsenic in maximum hand and wipe loadings. Analyses using arsenic handloading data from a study of children playing on CCA-treated play structures in Edmonton, Canada, indicate that the maximum handloading values significantly overestimate the exposure that occurs during actual play. The objective of our paper is to assess whether the dislodgeable arsenic residues from structures in the Edmonton study are comparable to those observed in other studies and whether they support the conclusion that the values derived by EPA using modeled maximum loading values overestimate hand exposures. We compared dislodgeable arsenic residue data from structures in the playgrounds in the Edmonton study to levels observed in studies used in EPA's assessment. Our analysis showed that the dislodgeable arsenic levels in the Edmonton playground structures are similar to those in the studies used by EPA. Hence, the exposure estimates derived using the handloading data from children playing on CCA-treated structures are more representative of children's actual exposures than the overestimates derived by EPA using modeled maximum values. Handloading data from children playing on CCA-treated structures should be used to reduce the uncertainty of modeled estimates derived using the SHEDS-Wood model.",
Arsenic,2088448,"Assessment on Pollution by Heavy Metals and Arsenic Based on Surficial and Core Sediments in the Cam River Mouth, Haiphong Province, Vietnam Abstract: ",
Arsenic,656755,"Protection of sodium arsenite-induced ovarian toxicity by coadministration of L-ascorbate (vitamin C) in mature wistar strain rat Abstract: Arsenic, a major water pollutant in India, produces toxic effects on female reproductive system in rodent models at the dose available in drinking water in arsenic-intoxicated zones. This study examines the coadministration of L-ascorbate (vitamin C) on ovarian steroidogenesis, plasma levels of gonadotrophins, brain monoamines, and ovarian as well as uterine peroxidase activities in sodium arsenite-treated rats. After sodium arsenite treatment, relative ovarian and uterine weights, ovarian Delta5-3beta-HSD and 17beta-HSD activities, plasma levels of gonadotrophins, norepinephrine levels in midbrain and diencephalon, and the activities of peroxidase in ovary and uterus were decreased significantly. On the other hand, serotonin levels in midbrain and diencephalon were increased significantly 28 days after sodium arsenite treatment at the dose of 0.4 ppm/100 g body weight/rat/day. All these parameters were protected significantly and in most cases were unchanged from control level when L-ascorbate at 25 mg/100 g body weight/rat/day was coadministered orally with sodium arsenite. This cotreatment of L-ascorbate with sodium arsenite also restored the estrous cycle in a regular manner. We concluded that L-ascorbate plays a pivotal role in maintaining normal ovarian activities and brain monoamines in arsenic-treated rats.",
Arsenic,1358531,RECENT ADVANCES IN METAL CARCINOGENESIS Abstract: HEEP COPYRIGHT: BIOL ABS. RRM BACTERIA MAMMALIAN CELL DNA POLYMERASE INFIDELITY DNA STRAND BREAK CROSS LINK MUTAGEN,
Arsenic,1019107,"Dietary selenium and arsenic affect DNA methylation in vitro in Caco-2 cells and in vivo in rat liver and colon Abstract: Selenium is an essential trace element for human health, and it has received considerable attention for its possible role as an anticarcinogenic agent. The purpose of the present study was to determine whether changes in the amount and the chemical form of selenium would affect DNA methylation and whether this effect would be modified by arsenic. Caco-2 cells, a human colon cancer cell line, were exposed to 0, 1 or 2 micromol supplemental selenite/L and 0, 1 or 2 micromol supplemental arsenite/L for 7 d. DNA isolated from Caco-2 cells not treated with selenite was significantly (P: &lt; 0. 0001) hypomethylated compared with that from cells treated with 1 or 2 micromol selenite/L. DNA isolated from Caco-2 cells not treated with arsenite was significantly (P: &lt; 0.0001) hypomethylated compared with DNA isolated from cells treated with 1 or 2 micromol arsenite/L. In addition, methylation of the p53 promoter region of Caco-2 cells decreased when cells were cultured in the absence of selenite and in the absence of arsenite. Sixty weanling male Fischer 344 rats were fed a torula yeast-based diet supplemented with 0, 0.1 or 2 mg selenium/kg diet as either selenite or selenomethionine in the presence or absence of 5 mg arsenic/kg diet as arsenite for 6 wk. Similar to the results with Caco-2 cells, rats fed selenium-deficient diets had significantly (P: &lt; 0.0001) hypomethylated liver and colon DNA compared with rats fed 0.1 or 2.0 microg selenium/g diets as either selenite or selenomethionine. Thus, alterations in DNA methylation may be a potential mechanism, whereby deficient dietary selenium increases liver and colon tumorigenesis.",
Arsenic,628437,"Metallothionein-1 and -2 expression in cadmium- or arsenic-derived human malignant urothelial cells and tumor heterotransplants and as a prognostic indicator in human bladder cancer Abstract: The goal of this study was to determine if the expression of the metallothionein (MT)-1/2 proteins might serve as a biomarker for the development of bladder cancer. A retrospective analysis of MT-1/2 staining was performed on 343 tissue sections from patients referred for the diagnosis of bladder cancer. The specimens were subdivided into six categories: benign, dysplastic, low-grade cancer, high-grade cancer with no evidence of invasion, high-grade cancer with evidence of invasion, and carcinoma in situ. There was no expression of MT-1/2 in benign lesions and low-grade cancers, a low incidence of expression in dysplastic lesions and high-grade cancers with no evidence of muscle invasion, and a significantly increased incidence of MT-1/2 in high-grade cancers that had invaded the underlying matrix. The expression of MT-1/2 varied in intensity from sample to sample and was focal in its expression. It was concluded from these findings that MT-1/2 may be a prognostic marker for cancers that are progressing to invade the underlying stroma of the bladder wall. The expression of MT-1/2 was also determined in a cell culture model of human urothelium that had been malignantly transformed by Cd2+ and As3+ and shown to be capable of tumor formation in nude mice. It was demonstrated that the expression of MT-1/2 in the tumor heterotransplants was similar to the pattern found in archival specimens of high-grade bladder cancers. The MT-1/2 staining in the heterotransplants was focal in pattern, varied in intensity, and highest in the less differentiated cells of the tumor. These findings indicate that the cell culture model may serve to help define the role of MT-1/2 expression in bladder cancer invasion.",
Arsenic,1026110,"Effects of coal combustion residues on survival, antioxidant potential, and genotoxicity resulting from full-lifecycle exposure of grass shrimp (Palaemonetes pugio Holthius) Abstract: Coal combustion residues (CCRs), largely derived from coal-fired electrical generation, are rich in numerous trace elements that have the potential to induce sublethal effects including oxidative stress, alterations in antioxidant status and DNA single strand breaks (SSB). CCRs are frequently discharged into natural and man-made aquatic systems. As the effects of CCRs have received relatively little attention in estuarine systems, the estuarine grass shrimp, Palaemonetes pugio, was chosen for this study. Grass shrimp were exposed in the laboratory to CCR-enriched sediments and food over a full life cycle. Survival to metamorphosis was significantly reduced in CCR-exposed larvae (17+/-4 versus 70+/-13% in the controls) but not in the juveniles or adults. The COMET assay, a general but sensitive assay for genotoxicity, was used to quantify DNA SSB in the adults. Total antioxidant potential was examined to assess the overall antioxidant scavenging capacity of CCR-exposed and non-exposed adult grass shrimp. Grass shrimp exposed to CCR significantly accumulated selenium and cadmium compared to unexposed shrimp, although an inverse relationship was seen for mercury accumulation. Chronic CCR exposure caused DNA SSB in hepatopancreas cells, as evidenced by the significantly increased percent tail DNA, tail moment, and tail length as compared to reference shrimp. However, no significant difference was observed in total antioxidant potential. Our findings suggest that genotoxicity may be an important mode of toxicity of CCR, and that DNA SSB may serve as a useful biomarker of exposure and effect of this very common, complex waste stream.",
Arsenic,2345787,"What do the trace metal contents of urine and toenail samples from Qatar's farm workers bioindicate? Abstract: Qatar's farm workers provide a unique population for exposure study: they are young, healthy males. This study combined trace element profiles in urine and toenail with survey information from 239 farm workers to assess the extent to which the biomarkers provide complementary exposure information. Urinary Mo levels (average=114 mu g/L) were elevated; average urinary values (mu/L) for all other elements were: V (1.02), Cr (0.55), Mn (2.15), Fe (34.1), Co (0.47), Ni (2.95), Cu (15.0), As (47.8), Se (25.7), Cd (1.09), Ba (225), Pb (2.50) and U (0.15). Average toenail concentrations (mg/kg) were: Mn (2.48), Cu (4.43), As (026), Se (0.58), Mo (0.07), Cd (0.03), Ba (1.00), Pb (0.51) and U (0.02). No significant association was found between corresponding elements in urine and toenails. Elemental profiles suggest groundwater (with the exception of Mo) and soil-dust-crop exposure pathways cannot account for elemental variations. The main factors moderating trace element contents are related to depuration processes involving participants' trace element body burden prior to work in Qatar, and interactions of trace element metabolic cycles which over-ride the exposure footprint. Toenail and urine need to be carefully validated before reliable use as biomarkers of exposure in general populations for most elements in the study. (C) 2014 Elsevier Inc. All rights reserved.",
Arsenic,1018815,"ATM status confers sensitivity to arsenic cytotoxic effects Abstract: Arsenic (As), a human carcinogen, represents a worldwide health problem due to the high number of people exposed to this element in their drinking water. Previously our group has demonstrated that As can impair lymphocyte cell proliferation in vitro and in vivo and can increase the level of P53 protein, with different responses to these effects between individuals. Recently it has been shown that ATM protein, responsible for the autosomal recessive disorder ataxia telangiectasia (AT), regulates P53. In this study the induced response of P53 was evaluated following exposure to As in human lymphoblastoid cell lines normal (+/+), heterozygous (+/-) or homozygous (-/-) for the mutant ATM gene. After 24 h As treatment we found a dose-dependent induction of P53 in normal and heterozygous cell lines, although differences between cell lines were observed. An increase in P21(WAF) protein, a main effector of P53 activation, was also observed in the same cell lines. In contrast, neither P53 nor P21 induction was detected in homozygous cells. The ATM (+/-) and (-/-) genotypes confer more sensitivity to As cytotoxic effects than the normal allelic condition. Paradoxically, ATM heterozygous cells were more sensitive to As, leading us to propose that this might be related to activation of apoptosis and removal of non-repairable cells. In contrast, in AT cells in which ATM is absent or mutated activation of P53 and its target genes is abrogated, allowing cells to replicate with damage in the presence of As, with cell death ensuing by a pathway different from P53.",
Arsenic,1509337,Effects of microbial processes on the fate of arsenic in paddy soil Abstract: ,
Arsenic,99932,Lead and arsenic levels in wines produced from vineyards where lead arsenate sprays are used for caterpillar control Abstract: Twenty-seven dry table wines from 14 wineries throughout Victoria were analysed for lead and arsenic. Wines originating from vineyards using lead arsenate insecticide for caterpillar control had mean levels of 0.31 mg litre--1 lead and 0.08 mg litre--1 arsenic. The mean levels in similar wines from wineries not using lead arsenate sprays were 0.03 mg litre--1 and less than 0.01 mg litre--1 respectively.,
Arsenic,1597359,"Accumulation of arsenic, lead, copper, and zinc, and synthesis of phytochelatins by indigenous plants of a mining impacted area Abstract: Several native plants, able to grow in an unconfined mining impacted area that is now in close vicinity with urban areas, were evaluated for their ability to accumulate heavy metals. The main soil contaminants were As, Pb, Cu, and Zn. Sampling of the rhizospheric metal polluted soil showed that Euphorbia prostrata Aiton, Parthenium incanum Kunth, and Zinnia acerosa (DC.) A. Gray were able to grow in the presence of high amounts of mixtures of these elements. The plants accumulated the metals in the above ground parts and increased the synthesis of thiol molecules. E. prostrata showed the highest capacity for accumulation of the mixture of elements (588 ?g g DW(-1)). Analysis of the thiol-molecules profile showed that these plants synthesized high amounts of long-chain phytochelatins, accompanied by low amounts of monothiol molecules, which may be related to their higher resistance to As and heavy metals. The three plants showed translocation factors from roots to leaves &gt;1 for As, Pb, Cu, and Zn. Thus, by periodically removing aerial parts, these plants could be useful for the phytoremediation of semi-arid and arid mining impacted areas, in which metal hyper-accumulator plants are not able to grow.",
Arsenic,2343482,"Emissions of C&D refuse in landfills: A European case Abstract: A field study was developed in a new landfill for refuse from construction and demolition (C&amp;D) material recovery plants of small size (4Ha.) in Europe, with the aim of evaluating the liquid and gas emissions in this type of facility at a large scale. It included characterization of the materials, monitoring leachate and gas quantity and composition. Besides thermometers, piezometers and sampling ports were placed in several points within the waste. This paper presents the data obtained for five years of the landfill life. The materials disposed were mainly made up of wood and concrete, similar to other C&amp;D debris sites, but the amount of gypsum drywall (below 3% of the waste) was significantly smaller than other available studies, where percentages above 20% had been reported. Leachate contained typical C&amp;D pollutants, such as different inorganic ions and metals, some of which exceeded other values reported in the literature (conductivity, ammonium, lead and arsenic). The small net precipitation in the area and the leachate recirculation into the landfill surface help explain these higher concentrations, thus highlighting the impact of liquid to solid (L/S) ratio on leachate characteristics. In contrast to previous studies, neither odor nuisances nor significant landfill gas over the surface were detected. However, gas samples taken from the landfill inside revealed sulfate reducing and methanogenic activity.",
Arsenic,1704076,"Distribution and Accumulation Characteristics of Heavy Metals in Sediments in Southern Sea Area of Huludao City, China Abstract: The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed modern sediment core can be used to analyze the accumulation and source of the pollutants using Cs-137 and Pb-210(ex). Thirty-five samples of surface sediment and two core sediments were collected from the southern sea area of Huludao City. The concentrations of copper (Cu), lead (Pb), chrome (Cr), zinc (Zn), arsenic (As) and mercury (Hg) in the surface sediments as well as Cu, Pb, Zn, Cr, Cs-137 and Pb-210(ex) in the core sediments were determined to research the spatial distribution and accumulation characteristics, and to analyze the sources and the potential risks of heavy metals. The results show that the pollution levels of Zn and Hg are serious, and 26 stations are at moderate or heavy ecological risks. The concentrations of the heavy metals increase from east to west, as well as from open sea to offshore marine area. The concentrations of heavy metals are not high in the sediments adjacent to the Jinzhou Bay, and the influence caused by the seawater exchange with the Jinzhou Bay is little. The concentrations of the heavy metals in the core sediments show low-high-low characteristic, and it coincides with the pollution history of Huludao City. The atmospheric deposition of heavy metals from the Huludao Zinc Plant is likely to be the main source of pollution without direct discharge of wastewater. The high concentrations of heavy metals appear on the upper sediment of 20 cm. The shallow sediment with high heavy metal contents might be exposed to surface when it was disturbed by the ocean engineering and big storm surge, then cause risk to the safety of aquaculture and human healthy.",
Arsenic,1016005,"MicroRNA-181b and microRNA-9 mediate arsenic-induced angiogenesis via NRP1 Abstract: Environmental exposure to inorganic arsenic compounds has been reported to have serious health effects on humans. Recent studies reported that arsenic targets endothelial cells lining blood vessels, and endothelial cell activation or dysfunction, may underlie the pathogenesis of arsenic-induced diseases and developmental toxicity. It has been reported that microRNAs (miRNAs) may act as an angiogenic switch by regulating related genes. The present study was designed to test the hypothesis that arsenite-regulated miRNAs play pivotal roles in arsenic-induced toxicity. Fertilized eggs were injected via the yolk sac with 100 ?nM sodium arsenite at Hamburger-Hamilton (HH) stages 6, 9, and 12, and harvested at HH stage 18. To identify the individual miRNAs and mRNAs that may regulate the genetic network, the expression profiles of chick embryos were analyzed by microarray analysis. Microarray analyses revealed that the expression of a set of miRNAs changed after arsenite administration, especially miRNA-9, 181b, 124, 10b, and 125b, which exhibited a massive decrease in expression. Integrative analyses of the microarray data revealed that several miRNAs, including miR-9 and miR-181b, might target several key genes involved in arsenic-induced developmental toxicity. A luciferase reporter assay confirmed neuropilin-1 (Nrp1) as a target of mir-9 and mir-181b. Data from the transwell migration assay and the tube-formation assay indicated that miR-9 and mir-181b inhibited the arsenic-induced EA.hy926 cell migration and tube formation by targeting NRP1. Our study demonstrates that the environmental toxin, sodium arsenite, induced angiogenesis by altering the expression of miRNAs and their cognate mRNA targets.",
Arsenic,2343543,"Assessment of soil geochemistry around some selected agricultural sites of Sri Lanka Abstract: Farming is the major source of income for the villagers of North-central Sri Lanka. However, chronic kidney disease of unknown etiology is a major health hazard in the area and it is assumed that agricultural contaminants are the major causative agents. This study focuses on the geochemistry of soils in the area to determine possible natural and anthropogenic impacts of the problem. X-ray fluorescence analysis was used to determine the abundance of selected major and trace elements. Results show that geo-enrichment for many elements indicates slight to significant variations between agricultural and non-agricultural soils. Geoaccumulation index (I (geo)) shows higher pollution levels of Pb and V (2 < I (geo) < 3) and very lower pollution levels of As, Zn, Cu, Fe and Mn (1 < I (geo) < 2) in agricultural soils. However, I (geo) for non-agricultural soils implies lack of contaminations (I (geo) < 1). Positive correlations of As with Pb and Zn and negative correlations with Cu, Ni and Cr suggest that they may have derived from different sources such as sulfide minerals of basement rocks, fertilizers and agrochemicals. The results of this study suggest that there is no significant threat from As and other trace elements to soils. The accumulation of these elements in agricultural fields may have been effectively controlled by seasonal farming practices. However, there is a potential environmental risk from elements such as Pb and V due to their significant enrichment in soils.",
Arsenic,1017330,"Oxidative damage in lymphocytes of copper smelter workers correlated to higher levels of excreted arsenic Abstract: Arsenic has been associated with multiple harmful effects at the cellular level. Indirectly these defects could be related to impairment of the integrity of the immune system, in particular in lymphoid population. To characterize the effect of Arsenic on redox status on this population, copper smelter workers and arsenic unexposed donors were recruited for this study. We analyzed urine samples and lymphocyte enriched fractions from donors to determinate arsenic levels and lymphocyte proliferation. Moreover, we studied the presence of oxidative markers MDA, vitamin E and SOD activity in donor plasma. Here we demonstrated that in human beings exposed to high arsenic concentrations, lymphocyte MDA and arsenic urinary levels showed a positive correlation with SOD activity, and a negative correlation with vitamin E serum levels. Strikingly, lymphocytes from the arsenic exposed population respond to a polyclonal stimulator, phytohemaglutinin, with higher rates of thymidine incorporation than lymphocytes of a control population. As well, similar in vitro responses to arsenic were observed using a T cell line. Our results suggest that chronic human exposure to arsenic induces oxidative damage in lymphocytes and could be considered more relevant than evaluation of T cell surveillance.",
Arsenic,1579252,"Batch effects and pathway analysis: Two potential perils in cancer studies involving DNA methylation array analysis Abstract: Background: DNA methylation microarrays have become an increasingly popular means of studying the role of epigenetics in cancer, though the methods used to analyze these arrays are still being developed and existing methods are not always widely disseminated among microarray users. Methods: We investigated two problems likely to confront DNA methylation microarray users: 1) batch effects; and 2) the use of widely available pathway analysis software to analyze results. First, DNA taken from individuals exposed to low and high levels of drinking water arsenic were plated twice on Illumina's Infinium 450K humanmethylation array, once in order of exposure and again following randomization. Second, we performed simulations in which random CpG sites were drawn from the 450K array and subjected to pathway analysis using Ingenuity's IPA software. Results: The majority of differentially methylated CpG sites identified in Run One were due to batch effects; few sites were also identified in Run Two. In addition, the pathway analysis software reported many significant associations between our data, randomly drawn from the 450K array, and various diseases and biological functions. Conclusions: Data from our own laboratory illustrate the pitfalls of not properly controlling for chip-specific batch effects as well as using pathway analysis software created for gene expression arrays to analyze DNA methylation array data. Impact: We present evidence that 1) chip-specific effects can simulate plausible differential methylation results; and 2) popular pathway analysis software developed for expression arrays can yield spurious results when used in tandem with methylation microarrays.",
Arsenic,1031417,"Histological and haematological disturbance caused by arsenic toxicity in mice model Abstract: Histological and hematological disturbance caused by Arsenic containing water were studied in mice model. Animal were divided into four groups. Control group exposed to arsenic free distilled water and 3 treatmental group exposed to the arsenic containing water with 30, 150 and 300 ppb. Blood samples and organs were collected after 40 days. Histopathological results revealed mild to severe type of necrosis and degenerative changes in kidney and liver of arsenic feed animals. Kidney of the 300 ppb group showed severe type of necrosis and degenerative changes in distal and proximal tubules. The renocytes of proximal and distal tubules were showing hydropic and fatty degeneration. Due to degenerative changes cells were showing cytoplasmic vacoulation and cytoplasmic and nuclear blebbing. Glomeruli cells were contracted and increased the bowman's spaces. Varied degrees of changes were also observed in 30 and 150 ppb exposed group. Necrosis of hepatocytes and cytoplasmic blebbing were also observed. The sinusoidal spaces were expanded due to shrinkage and necrosis of hepatocytes. Spleenocytosis occurred in spleen and the parenchymal and mesenchymal cells were replaced by connective tissue. The lymphocytes were severely damaged by arsenic toxicity. White Blood Cells (WBCs), Red Blood Cells (RBCs) and hemoglobin level in control groups were in normal range where as level were significantly decreased with the increase dose of arsenic in the respective treatmental groups. The data was analyzed statistically and was found that significant was found among the group (p&lt;0.05).",
Arsenic,1348852,"Both IKKalpha and IKKbeta are implicated in the arsenite-induced AP-1 transactivation correlating with cell apoptosis through NF-kappaB activity-independent manner Abstract: Arsenite has been well-proved to act as both an environmental carcinogen as well as a tumor therapeutic agent. AP-1 is one of the transcription factors that can be induced upon arsenite stimulation. However, the study on the mechanism and the function of the arsenite-induced AP-1 transactivation remains far complete. Here we demonstrated that high dose of arsenite induced apoptotic response in mouse fibroblasts correlating with AP-1 transactivation, which events were mediated by both IKKalpha and IKKbeta, two major protein kinases responsible for NF-kappaB activation. In addition, the regulatory effect of IKKs on the arsenite-induced AP-1 activation was delivered by sequential induction of GADD45alpha expression and the activation of MAPKK (MKK3/4/6) and MAPK (JNK and p38K)-dependent pathways. We further provided evidence that p50, but not p65 subunit of NF-kappaB, was involved in GADD45alpha induction and the subsequent MAPKK/MAPK/AP-1 activation under arsenite exposure, while functional NF-kappaB induced by arsenite stimulation consisted of p65 but not of p50 subunit. Therefore, we concluded that both IKKalpha and IKKbeta can mediate arsenite-induced AP-1 transactivation through NF-kappaB activity-independent manner.",
Arsenic,2279084,"Temporal trends of contaminants in cod from Icelandic waters Abstract: Contaminants have been analyzed in cod (Gadus morhua) since 1990 as part of the national monitoring program for the environmental conditions in the sea around Iceland. The aim of this study was to determine the temporal trends of persistent organic pollutants (POPs: polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl dichloroethene (p,p'-DDE), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), chlordanes (CHLs) and toxaphenes (Tox)) and trace elements (As, Cd, Cu, Hg, Pb, Se and Zn) in cod over the last two decades at two different locations in the Arctic Ocean north of Iceland. The relationship between the contaminant concentrations and biological covariates was also determined. All of the POPs showed decreasing trends but the trace elements showed no clear signs of trend except arsenic which showed an increasing trend and zinc which showed a decreasing trend. The concentration of the POPs were lower or similar in the Icelandic cod compared to cod sampled in Norway, the Barents Sea and in the Baltic Sea, except for HCB which was higher in the Icelandic cod compared to the Norwegian cod. The concentration of the trace elements As, Cu, Hg and Zn were similar in the Icelandic cod compared to cod sampled in Norway and Greenland but the concentration of Cd was higher in the Icelandic cod. The inclusion of the biological covariates was found to be important for the statistical analysis. The POPs had a positive relationship with liver fat content but negative relationship with liver weight. The trace elements had a negative relationship with liver fat and liver weight except As which had positive relationship with liver weight. Only positive relationships were observed between the contaminant concentrations and length.",
Arsenic,1025172,"Measurement of quenching cross sections for laser-induced fluorescence of atomic arsenic Abstract: The measurement of collisional quenching cross sections for the (4p)(2) (5s)(1) (4)P(1/2) state of atomic arsenic is reported. The arsenic (4)P(1/2) state was prepared by excitation from the (4p)(3) (4)S(3/2) ground state with 197.2-nm laser radiation. The fluorescence signal from the (4p)(2) (5s)(1) (4)P(1/2) ? (4p)(3) (2)D(1/2) transition was monitored at 249.3 nm. Quenching cross sections were obtained for hydrogen, methane, nitrogen, carbon monoxide, and ethylene.",
Arsenic,1936061,"Qualitative and Quantitative Contrast Enhanced Ultrasonography of the Pancreas Using Bolus Injection and Continuous Infusion Methods in Normal Dogs Abstract: Quantitative contrast enhanced ultrasound is a major breakthrough for ultrasound imaging in recent years. However, contrast enhancement of the pancreas is brief with bolus injection. To assess if continuous infusion of Sonazoid(®) can prolong the duration of pancreatic enhancement over bolus injections, eight adult dogs received bolus injection and continuous infusion of Sonazoid(®) on separate days. Contrast enhanced ultrasound of the pancreatic parenchyma and proximal descending duodenum was performed, and time intensity curves reflecting tissue perfusions were generated. Perfusion parameters- time to initial upslope, peak time, time to wash-out and peak intensity were calculated and evaluated. Fast wash-in to intense peak, followed by rapid wash-out was observed for time intensity curves of bolus injection. With continuous infusion, contrast wash-in to peak intensity was gradual, followed by long plateau and slow wash-out. Median contrast enhancement durations of the pancreas and duodenum were significantly prolonged by continuous infusion from 11 sec (range, 10 to 23 sec) and 16 sec (range, 3 to 43 sec) at bolus injection to 205 sec (range, 170 to 264 sec, P&lt;0.01) and 193 sec (range, 169 to 216 sec, P&lt;0.05), respectively. Median peak intensity of the pancreas was 100.9 MPV (range, 80.2 to 124.3 MPV) at bolus injection and 77.6 MPV (range, 58.2 to 99.5 MPV, P&lt;0.05) at continuous infusion. Prolonged continuous imaging is afforded by continuous infusion of contrast agent. Peak intensity of the pancreas was slightly diminished in continuous infusion, but offered adequate imaging subjectively.",
Arsenic,1251423,"Heat-shock protein-73 protects against small intestinal warm ischemia-reperfusion injury in the rat Abstract: <strong>BACKGROUND: </strong>The protective effects of heat-shock protein (hsp) in rat small intestinal warm ischemia-reperfusion (I/R) injury are poorly understood.<br /><br /><strong>METHODS: </strong>Hsp-73 expression was induced in rat small intestine with use of sodium arsenite injected (6 mg/kg) through a catheter cannulated into the left common carotid artery 24 hours before ischemia (group 1). In the control group an equal volume of phosphate-buffered saline solution was injected (group 2). To block the induction of hsp-73 expression, sodium arsenate and quercetin (5 mg/kg) were injected (group 3).<br /><br /><strong>RESULTS: </strong>The mean peak plasma levels of tumor necrosis factor-alpha and cytokine-induced neutrophil chemoattractant after reperfusion were lower in group 1 than in group 2. The tissue myeloperoxidase activity after reperfusion was lower in group 1 than in group 2. The mean peak plasma level of interleukin-10 after reperfusion was higher in group 1 than in group 2. The induction of hsp-73 expression reduced the synthesis of nitric oxide and the magnitude of the small intestinal warm I/R injury. The results in group 3 were similar to those in group 2.<br /><br /><strong>CONCLUSION: </strong>Hsp-73 protects against small intestinal warm I/R injury by inhibiting the synthesis of inflammatory cytokines and the activation of neutrophils and by accelerating the synthesis of anti-inflammatory cytokines.",
Arsenic,1579284,"Antibacterial evaluation of novel organoarsenic compounds by the microcalorimetric method Abstract: Antibacterial activities of novel organoarsenic compounds As(III)-containing Schiff bases on Escherichia coli (CCTCCAB91112) were investigated by microcalorimetry in this study. The experimental result showed that the arsenic(III)-containing Schiff bases at micromolar concentration exhibit strong inhibition on the E. coli. Specifically, the growth rate constant k decreased, and the generation time tG and the inhibitory ratio I (percentage) increased with the increased dose of the arsenicals as inhibitors. All of the arsenicals display the feature of considerable lag phase inhibition on the cell growth. The compound 4-(4-bromobenzaliminyl)phenylarsenoxide makes the lag phase of E. coli cell growth cycles to reach 650 min at 5 ?mol/L. The compounds with donating electron groups at aromatic ring B have lower IC50 to present higher antibacterial activity. The compound 4-(4-hydroxyl-3-methoxylbenzaliminyl)phenylarsenoxide has the lowest IC50 (1.82 ?mol/L) to show the strongest antibacterial activity among them.",
Arsenic,1508698,"Arsenic release from deep natural solid matrices under experimentally controlled redox conditions Abstract: We investigated the role of iron (Fe) on arsenic (As) release from two samples of a natural deep soil collected in an aquifer body in the Emilia-Romagna Region, Italy. Each sample is representative of a different solid matrix, i.e., sand and vegetal matter. Batch experiments were performed by applying alternating aerobic/anaerobic conditions to the samples under a range of redox and pH conditions, consistent with the corresponding values measured in the field. Arsenic mobilization was triggered by abrupt and rapid changes in redox conditions and displayed a clear correlation with oxidation/reduction potential for both solid matrices. Vegetal matter showed high binding capacity and large As concentration release. Arsenic release was also correlated with Fe released from the solid matrices. Our results suggest that the environmentally critical As concentrations detected in some aquifers in the Emilia-Romagna Region are consistent with (a) the occurrence of high natural As content in the component of the host porous medium associated with vegetal matter and (b) the effect of possible sharp localized (and temporally oscillating) variations in redox conditions.",
Arsenic,79805,"Controlling the healthy worker survivor effect: An example of arsenic exposure and respiratory cancer Abstract: OBJECTIVE: This investigation sought to examine whether methods proposed to control the healthy worker survivor effect would influence the shape or magnitude of the dose-response curve for respiratory cancer induced by arsenic. METHODS: Results from an unadjusted analysis are compared with results obtained by applying four different methods for control of the healthy worker survivor effect to data on arsenic exposure and respiratory cancer. The four methods are: exposure lag, adjustment for work status, cohort restriction, and the G null test. RESULTS: Cohort restriction gave erratic results depending upon the minimum years of follow up used. Exposure lag substantially increased the rate ratios and a non-linear shape (decreasing slope) compared with an unlagged analysis. Adjusting for work status (currently employed upsilon retired or otherwise not employed) yielded slightly higher rate ratios than an unadjusted analysis, with an overall shape similar to the baseline analysis. Results from the G null test procedure of Robins (1986), although not directly comparable with the baseline analysis, did show an adverse effect of exposure that seemed to reach a maximum when exposure was lagged between 10 and 20 years. CONCLUSIONS: All results confirm an adverse effect of arsenic exposure on respiratory cancer. In these data, it seems that the healthy worker survivor effect was not strong enough to mask the strong effect of arsenic exposure on respiratory cancer. Nevertheless, several methods show a stronger association between arsenic exposure and respiratory cancer after adjustment for the healthy worker survivor effect, suggesting that for weaker causal associations, studies not controlling for this source of bias will have low power to detect results. Although the G methods are theoretically the most unbiased, further work elucidating the validity of the assumptions underlying lagging, adjustment for work status, and the G methods are needed before clear recommendations can be made.",
Arsenic,2337194,"Recycling of nickel smelter slag for arsenic remediation--An experimental study Abstract: In this study, recycled Ni smelter slag has been used as a reactive medium for arsenic (As) removal from aqueous solutions. The results of the study showed that 10.16-11.43-cm long columns containing 451-550 g of slag operated for at least 65 days were able to remove 99-100 % As species from continuously flowing contaminated water at an initial As concentration of 10 mg/L. The removal capacities were found to be 1.039 to 1.054 mg As per g of slag. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy data also showed that electrostatic attraction and oxidation-reduction reactions between As species and mixed iron oxides present in the slag were the main mechanisms for the removal of arsenic from aqueous solutions. Theoretical multiplet analysis of XPS data revealed that the amount of goethite in the slag increased from 22 to 60 % during arsenic removal by adsorption and the percentage of magnetite decreased from 50 to 40 %. These changes indicate that redox-mediated reactions occurred as part of the As(V) removal process. Raman spectroscopy studies confirmed that, in addition to surface reactions, internal interactions between the slag and arsenic also occurred. The findings of the study suggest that recycled Ni smelter slag could be an effective low-cost reactive medium for a subsurface remediation system, such as a permeable reactive barrier. Recycling of waste material (slag) for the removal of another waste (arsenic) can significantly reduce the environmental footprint of metallurgical operations and hence contribute to sustainable development. Such recycling also decreases slag disposal costs and eliminates the need to purchase commercial reactive material or obtain expensive natural material for remediation purposes.",
Arsenic,1349667,"Functional activity of Th1 and macrophages from children environmentally exposed to arsenic Abstract: Arsenic exposure has been associated with toxic effects at different levels including the immune system. Data from animal studies and scarce evidence from human adults, have shown that arsenic alters some immune system cells and affect T lymphocyte proliferation. However little is known about effects on children, a high risk group for the immunotoxicity of several chemicals. We studied the effect of arsenic exposure on Th1 and macrophage activation of children exposed to arsenic in drinking water (3.5 to 295.8 micrograms/L). We studied 87 children aged 6-10 years and having total urinary arsenic concentrations ranging from 12.3 to 1, 411 micrograms/L, determined by HGAAS. Th1 function was evaluated by measuring the capability of PHA-stimulated T lymphocytes to activate macrophages. Macrophage function was evaluated in the absence of T cells by direct activation with rhIFN-? plus lipopolysaccharide. Macrophage activation was evaluated by superoxide anion and nitric oxide production. Superoxide anion production in directly activated macrophages was positively associated with total arsenic urinary concentrations whereas a negative association was observed with nitric oxide production. No significant association was found with macrophage activity in response to Th1 stimulation. These data suggest that macrophage activation in children is a relevant target for arsenic exposure. This effect could be related with a decreased resistance to those infections where macrophages play a protective role. Work supported by CONACYT 34508-M to ESCA.",
Arsenic,2298704,"Arsenic(V) Reduction in Relation to Iron(III) Transformation and Molecular Characterization of the Structural and Functional Microbial Community in Sediments of a Northern Utah, Basin-Fill Aquifer Abstract: Basin-fill aquifers of the Southwest U.S. are associated with elevated concentrations of arsenic (As) in groundwater. Many private domestic wells in the Cache Valley Basin, UT, have As concentrations in excess of the U.S. EPA drinking water limit. Thirteen sediment cores were collected from the center of the valley at the depth of the shallow groundwater and were sectioned into layers based on redoxmorphic features. Three of the layers, two from redox transition zones and one from a depletion zone, were used to establish microcosms. Microcosms were treated with groundwater (GW) or groundwater plus glucose (GW+G), to investigate the extent of As reduction in relation to iron (Fe) transformation, and to characterize the microbial community structure and function by sequencing 16S rRNA and arsenate dissimilatory reductase (arrA) genes.Under carbon limited conditions of the GW treatment, As reduction was independent of Fe reduction, despite the abundance of Geobacter and Shewanella related sequences, genera that include a variety of dissimilatory iron reducing bacteria. The addition of glucose, an electron donor and carbon source, caused substantial shifts toward Clostridium related organisms dominating the bacterial community, and As reduction was correlated with Fe reduction for the sediments from the redox transition zone. The arrA gene sequencing from microcosms at Day 54 of incubation showed the presence of 14 unique phylotypes, none of which were related to any previously described arrA gene sequence, suggesting a unique community of the dissimilatory arsenate respiring bacteria in the Cache Valley Basin.",
Arsenic,1936171,"The determination of some heavy metals and minerals in the tissues and organs of the Capoeta umbla fish species in relation to body size, sex, and age Abstract: In this study, the levels of iron, copper, zinc, (manganese), cobalt, cadmium, lead, chrome, arsenic, mercury, nickel, calcium, and magnesium in the muscle, gill, skin, liver, gonad, and kidney of Capoeta umbla caught from Lake Hazar, Elaz??, Turkey were investigated. The concentrations of detected heavy metals were the highest in the liver and the lowest in the muscle. In addition, it has been found that the concentrations of heavy metals and minerals were found to be different in various tissues and organs. The amounts of heavy metals showed differences according to the weight, length, sex, and age groups of the fish. The results were discussed and compared with tolerable values for heavy metals provided by the EPA, WHO, FAO, and Turkish Food Codex to determine whether this species has any risk for human consumption.",
Arsenic,1337694,"Antimony, arsenic and lead distribution in soils and plants of an agricultural area impacted by former mining activities Abstract: An agricultural area impacted by the former exploitation of an arsenical lead-antimony deposit was studied in order to assess the current and eventual environmental and health impacts. Samples of soils and cultivated (wheat) and spontaneously growing plants were collected at different distances from the mine pits and analyzed for the toxic element content and distribution. The soil total concentrations of Sb, As and Pb found in the uppermost soil layer (14.1-324, 246-758 and 757-10,660mgkg(-1), respectively) greatly surpass their maximum tolerable levels in agricultural soils. Wheat grain Pb concentrations (0.068-1.36mgkg(-1)) exceed the prescribed health standard, whereas Sb (&lt;0.05-0.103mgkg(-1)) and As (&lt;0.05-0.126mgkg(-1)) concentrations are below the permissible limits fixed for cereals. Of the spontaneously growing plants, Dactylis glomerata L. shows a relatively high root Pb accumulation and a very low Pb translocation, suggesting its feasibility to be used in Pb phytostabilization strategies.",
Arsenic,1381219,DETERMINATION OF ARSENIC IN ENVIRONMENTAL AND BIOLOGICAL SAMPLES BY FLOW INJECTION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HYDRIDE GENERATION PRECISION ANALYTICAL METHOD,
Arsenic,1340104,"Arsenic resistance and cycling in earthworms residing at a former gold mine in Canada Abstract: Earthworms (Lumbricus castaneous and Dendrodrilus rubidus), their host soils and leaf litter were collected from a former gold mine with widespread arsenic (As) contamination in Nova Scotia, Canada and determined for total and speciated As. Resistance to As toxicity was investigated by measurement of DNA damage in exposed earthworm populations using the comet assay. Arsenobetaine (AB) was observed at low concentration in the earthworms but not in the host soil or leaf litter. Several different organoarsenic species were observed in the leaf litter and only inorganic As was found in the host soils. The results suggest that 1) adaptation to As toxicity in earthworms is widespread and not particular to a single species, 2) AB originates in the earthworm and not the consumed soil or leaf litter and 3) as previously hypothesised (Button et al., 2010), biotransformation of inorganic As to AB is not likely involved in the adaptation.",
Arsenic,1797856,"Nanostructured iron(III)-copper(II) binary oxide: A novel adsorbent for enhanced arsenic removal from aqueous solutions Abstract: To obtain a highly efficient and low-cost adsorbent for arsenic removal from water, a novel nanostructured Fe-Cu binary oxide was synthesized via a facile co-precipitation method. Various techniques including BET surface area measurement, powder XRD, SEM, and XPS were used to characterize the synthetic Fe-Cu binary oxide. It showed that the oxide was poorly crystalline, 2-line ferrihydrite-like and was aggregated with many nanosized particles. Laboratory experiments were performed to investigate adsorption kinetics, adsorption isotherms, pH adsorption edge and regeneration of spent adsorbent. The results indicated that the Fe-Cu binary oxide with a Cu: Fe molar ratio of 1:2 had excellent performance in removing both As(V) and As(III) from water, and the maximal adsorption capacities for As(V) and As(III) were 82.7 and 122.3 mg/g at pH 7.0, respectively. The values are favorable, compared to those reported in the literature using other adsorbents. The coexisting sulfate and carbonate had no significant effect on arsenic removal. However, the presence of phosphate obviously inhibited the arsenic removal, especially at high concentrations. Moreover, the Fe-Cu binary oxide could be readily regenerated using NaOH solution and be repeatedly used. The Fe-Cu binary oxide could be a promising adsorbent for both As(V) and As(III) removal because of its excellent performance, facile and low-cost synthesis process, and easy regeneration.",
Arsenic,2347735,"Heavy Metal Accumulation In the Leaves, Stem and Root of the Invasive Submerged Macrophyte Myriophyllum spicatum L. (Haloragaceae): An Example of Kadin Creek (Mugla, Turkey) Abstract: In this study, the existence of heavy metals such as chromium (Cr), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) their distribution in the organs of plant and their bioaccumulation rates in water samples and Myriophyllum spicatum which were collected from the Kadin Creek in seasonal periods between 2011 and 2012 were analyzed. Heavy metal concentrations in the mineralized plant and water samples were determined with Inductive coupled plasma with mass spectroscopy (ICP-MS). Results showed the maximum heavy metal concentrations, in the root and minimum heavy metal concentrations, except chromium, in the stem. The distribution of heavy metals As, Cd, Hg and Pb was in the form of root &gt; leaf &gt; stem; the distribution of Cr was in the root &gt; stem &gt; leaf. There was a strong negative correlation between the suspended solid matter and heavy metal concentrations in the plant tissues. Heavy metal accumulation showed increase generally in fall. Heavy metals in the water were sorted as Pb &gt; Cr &gt; As &gt; Hg &gt; Cd by their mean concentrations. According to the factor data of bioconcentration, the order of heavy metal accumulation in the plant was As &gt; Cr &gt; Pb &gt; Hg &gt; Cd.",
Arsenic,1337550,"Toxic metals and essential elements in hair and severity of symptoms among children with autism Abstract: Objective: The objective of this study was to assess the levels of ten toxic metals and essential elements in hair samples of children with autism, and to correlate the level of these elements with the severity of autism.Method: The participants were 44 children, age 3 to 9 years, with Autistic Spectrum Disorder (ASD) according to Diagnostic and Statistical Manual of Mental Disorders 4th Edition, (DSM-IV). The severity of autistic symptomatology was measured by the Childhood Autism Rating Scale (CARS). Hair analysis was performed to evaluate the long term metal exposure and mineral level.Results: By comparing hair concentration of autistic vs nonautistic children, elevated hair concentrations were noted for aluminum, arsenic, cadmium, mercury, antimony, nickel, lead, and vanadium. Hair levels of calcium, iron, iodine, magnesium, manganese, molybdenum, zinc, and selenium were considered deficient. There was a significant positive correlation between lead &amp; verbal communication (p = 0.020) and general impression (p = 0.008). In addition, there was a significant negative correlation between zinc &amp; fear and nervousness (p = 0.022).Conclusion: Our data supports the historic evidence that heavy metals play a role in the development of ASD. In combination with an inadequate nutritional status the toxic effect of metals increase along with the severity of symptoms.",
Arsenic,627194,"Genotoxicity of arsenical compounds Abstract: With respect to global human health hazard, arsenic (As) is one of the most important environmental single substance toxicants. Currently, millions of people all over the world are exposed to the ubiquitous element in exposure levels leading to long-term toxicity, in particular cancer. Unfortunately, it has not been elucidated up to now how As mechanistically leads to the induction of neoplasia. Besides its tumorigenic potential, As has been shown to be genotoxic in a wide variety of different experimental set-ups and biological endpoints. In vitro, the element was shown to induce chromosomal mutagenicity like micronuclei, chromosome aberrations, and sister chromatid exchanges. It mainly acts clastogenic but also has an aneugenic potential. Instead, its potential to induce point mutations is very low in bacterial as well as in mammalian cell systems. However, in combined exposure with point mutagens in vitro, As was shown to enhance the frequency of chemical mutations in a synergistic manner. Additionally, As was shown to induce chromosome aberrations and micronuclei in vivo in experiments with mice. After long-term exposure to As-contaminated drinking water, the great majority of human biomonitoring studies found elevated frequencies of DNA lesions like micronuclei or chromosome aberrations. Respective occupational studies are few. Like it is the case for As carcinogenicity, it is not known through which mechanism the genotoxicity of As is mediated, although the data available indicate that As may act indirectly on DNA, i.e. via mechanisms like interference of regulation of DNA repair or integrity. Because of the indirect mode of action, it has been discussed as well that As's genotoxicity may underlie a sublinear dose-response relationship. However, various problems like non-standardized test systems and experimental variability make it impossible to prove such statement. Basically, to be able to improve risk assessment, it is of crucial importance to scientifically approach the mechanistic way of induction of As's genotoxicity and carcinogenicity.",
Arsenic,627207,"Arsenic cancer risk confounder in southwest Taiwan data set Abstract: Quantitative analysis for the risk of human cancer from the ingestion of inorganic arsenic has been based on the reported cancer mortality experience in the blackfoot disease (BFD)–endemic area of southwest Taiwan. Linear regression analysis shows that arsenic as the sole etiologic factor accounts for only 21% of the variance in the village standardized mortality ratios for bladder and lung cancer. A previous study had reported the influence of confounders (township, BFD prevalence, and artesian well dependency) qualitatively, but they have not been introduced into a quantitative assessment. In this six-township study, only three townships (2, 4, and 6) showed a significant positive dose–response relationship with arsenic exposure. The other three townships (0, 3, and 5) demonstrated significant bladder and lung cancer risks that were independent of arsenic exposure. The data for bladder and lung cancer mortality for townships 2, 4, and 6 fit an inverse linear regression model (p < 0.001) with an estimated threshold at 151 ?g/L (95% confidence interval, 42 to 229 ?g/L). Such a model is consistent with epidemiologic and toxicologic literature for bladder cancer. Exploration of the southwest Taiwan cancer mortality data set has clarified the dose–response relationship with arsenic exposure by separating out township as a confounding factor. Key words: arsenic, blackfoot disease, bladder cancer, cancer risk, confounder, dose–response relationship, southwest Taiwan, threshold model.",
Arsenic,1597439,"Factor and cluster analysis of water quality data of the groundwater wells of Kushtia, Bangladesh: Implication for arsenic enrichment and mobilization Abstract: The study area is located in the southwestern part of Bangladesh. Twenty-six groundwater samples were collected from both shallow and deep tube wells ranging in depth from 20 to 60 m. Multivariate statistical analyses including factor analysis, cluster analysis and multidimensional scaling were applied to the hydrogeochemical data. The results show that a few factors adequately represent the traits that define water chemistry. The first factor of Fe and HCO3 is strongly influenced by bacterial Fe (III) reduction which would raise both Fe and HCO3 concentrations in water. Na, Cl, Ca, Mg and PO4 are grouped under the second factor representing the salinity sources of waters. The third factor, represented by As, Mn, SO4 and K is related to As mobilization processes. Cluster analysis has been applied for the interpretation of the groundwater quality data. Initially Piper methods have been employed to obtain a first idea on the water types in the study area. Hierarchical cluster analysis was carried out for further classification of water types in the study area. Twelve components, namely, pH, Fe, Mn, As, Ca, Mg, Na, K, HCO3, Cl, SO4 and NO3 have been used for this purpose. With hierarchical clustering analysis the water samples have been classified into 3 clusters. They are very high, high and moderately As-enriched groundwater as well as groundwater with elevated SO4.",
Arsenic,1337331,"Removal of arsenite(As(III)) and arsenate(As(V)) by synthetic pyrite (FeS(2)): Synthesis, effect of contact time, and sorption/desorption envelopes Abstract: Reliable techniques for synthesizing pyrite are necessary in order to develop effective treatment methods that use pyrite to remove arsenic from water and to stabilize arsenic in wastes. The Fe(3+)/HS(-) values of 0.500 and 0.571 at 60°C and pH values ranging from 3.6 through 5.6 were found to produce pyrite most efficiently. Removal of As(V) was faster than removal of As(III) and the extent of removal of both As(III) and As(V) were more accurately described by the Langmuir adsorption model. Removal of As(III) was observed to increase as pH increased across the range investigated (pH 7-10). However, an optimum pH in the range between pH 8 and pH 9 was observed for removal of As(V). Sorption envelopes for As(III) showed low removal at low pH, increasing removal as pH was increased and moderate irreversibility as pH was titrated backward. Sorption envelopes for As(V) showed similar behavior except low removals were observed initially at high pH, removals increased as pH decreased and moderate to high levels of irreversibility were observed as pH was raised back to the initial values.",
Arsenic,1030583,"Arsenic in Mexican children exposed to contaminated well water Abstract: This cross-sectional study measures the arsenic level in school children exposed to contaminated well water in a rural area in México. Arsenic was measured in hair by hydride generation atomic absorption spectrophotometry. Overall, 110 children were included (average 10 years-old). Among 55 exposed children, mean arsenic level on hair was 1.3 mg/kg (range &lt;0.006-5.9). All unexposed children had undetectable arsenic levels. The high level of arsenic in water was associated to the level in hair. However, exposed children drank less well water at school or at home than unexposed children, suggesting that the use of contaminated water to cook beans, broths or soups may be the source of arsenic exposure.",
Arsenic,2347810,"Mn(IV) promotion mechanism for the photocatalytic oxidation of arsenite by anatase-TiO2 Abstract: A Ti-Mn hybrid oxide (Ti-Mn-HO) that simultaneously contained anatase-TiO2 and Mn3O4 was prepared and applied to arsenite photocatalytic oxidization (PCO) under UV irradiation. X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive spectrometer (SEM/EDS), transmission electron microscopy (TEM) and a N-2 adsorption-desorption method were employed to characterize the morphology of the catalyst. Kinetics experiments indicated that Mn3O4 promoted the PCO-adsorption process of arsenite [As(III)] better than either pure anatase-TiO2 under UV irradiation or Ti-Mn-HO without UV exposure. The cause of this phenomenon was investigated using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Finally, a synergistic effect for the transformation of photoproduct holes and electrons between the TiO2 and Mn3O4 phases is assumed.",
Arsenic,2337171,"Disturbances of trace element metabolism in ESRD patients receiving hemodialysis and hemodiafiltration Abstract: <strong>INTRODUCTION: </strong>Accumulation of trace elements occurs in conditions of decreased kidney function. In some conditions, increased trace elements can have toxic features. On the other hand, studies are showing that concentration of some trace elements could be decreased in ERSD patients as well. The most important factor affecting trace element concentration in ERSD patients is the degree of renal failure and the usage of replacement therapy.<br /><br /><strong>MATERIALS AND METHODS: </strong>We analyzed the trace elements' (boron, aluminum, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, rubidium, strontium, cadmium, cesium, barium and lead) concentration in the whole blood of 41 ESRD patients who were treated with hemodialysis and hemodiafiltration and also of 61 healthy blood donors. In addition, comparison of trace element blood levels of patients receiving hemodialysis and hemofiltration was carried out. Whole blood trace element concentration was determined using inductive coupled plasma mass-spectrometry (ICPMS).<br /><br /><strong>RESULTS: </strong>Levels of boron, aluminum, vanadium, chromium, manganese, zinc, strontium, cadmium, barium and lead were significantly increased in ESRD patients. Significantly decreased levels were observed for nickel, arsenic, selenium and rubidium. Blood levels of cobalt, copper, cadmium and lead in hemodialysis patients were significantly higher compared to patients receiving hemodiafiltration.<br /><br /><strong>CONCLUSIONS: </strong>ESRD is accompanied with serious and multidirectional changes of trace element blood levels. The highest degree of blood level increases were observed for nonessential and toxic trace elements. Disorders of essential trace elements were manifested in a minor degree. Besides this, there were observed differences of trace element concentrations between ESRD patients receiving hemodialysis and hemo-diafiltration.",
Arsenic,1021617,"Total and inorganic arsenic in marketed food and associated health risks for the Catalan (Spain) population Abstract: Inorganic arsenic (iAs) is considered to be a human carcinogen. In this paper, total (As) and iAs contents of 215 food products and drinks (i.e., seafood, fruits and vegetables, meat products, oils and fats, rice and rice products, seasonings, and alcoholic drinks) marketed in Catalonia (Spain) were quantified by inductively coupled plasma-mass spectrometry. The analytical method described was used for different food products, obtaining feasible results without the need to couple LC-ICP-MS for iAs. Daily As and iAs intakes for the average adult Catalan consumer were estimated at 354 and 6.1 ?g/day/person, respectively, using consumption data from the Catalan Nutrition Survey (ENCAT). The highest As content was found in seafood, contributing 96% of dietary As intake, whereas rice presented the highest iAs values, corresponding to 67% of dietary iAs intake. As cooking process may affect iAs content, boiled rice was evaluated, showing an iAs reduction (up to 86%) when using higher water volumes (30:1 water/rice ratio) than those used in previous studies. This iAs exposure was slightly below the exposure risk range stated by the European Food Safety Authority (0.3-8 ?g/kg of body weight/day), although the possibility of a risk to the population with high rice consumption cannot be excluded.",
Arsenic,2345757,"Bacterial Diversity and Community Structure in High Arsenic Aquifers in Hetao Plain of Inner Mongolia, China Abstract: The bacterial diversity and community structure of high arsenic (As) aquifers was investigated using an integrated approach adopting both geochemistry and molecular biology (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library analyses). Nine borehole sediments and one groundwater sample from the living place of a villager (affected by arseniasis) and 12 sediments from a control borehole in Hetao Plain were investigated. The As concentrations ranged from 33.6 to 77.6mg/kg in high As borehole sediments and 1.5 to 5.8mg/kg in those samples from the control. The As concentration in the groundwater was 744.8g/L. Ratios between As(III) and total As in high As sediments increased gradually with depth and ranged from 0.02 to 0.34. Similarly, the Fe(II)/total Fe presented the same increasing trend with depth. The correlation between TOC contents and total As was positive. High concentrations of total As, S, Fe and TOC were found in clay and low in sand samples. Phylogenetic analysis showed significantly different bacterial communities among high As sediments, control sediments and the high As groundwater. Both DGGE and 16S rRNA gene clone library results showed that the high As sediments were dominated by Thiobacillus, Pseudomonas, Brevundimonas, and Hydrogenophaga, with Thiobacillus being distinctly dominant (63.5%). Whereas the low As sediments were dominated by some other genera including Psychrobacter, Massilia and Desulfotalea. The bacterial populations in the high As groundwater mainly included Pseudomonas, Acinetobacter and Aquabacterium. These results improve our understanding of the bacterial diversity in high As aquifers in Hetao Plain and suggest how specific bacterial populations help mediate the mobilization of As into high As groundwaters.",
Arsenic,1015897,"In vitro study of transporters involved in intestinal absorption of inorganic arsenic Abstract: Inorganic arsenic (iAs) [As(III)+As(V)] is a drinking water contaminant, and human exposure to these arsenic species has been linked with a wide range of health effects. The main path of exposure is the oral route, and the intestinal epithelium is the first physiological barrier that iAs must cross in order to be absorbed. However, there is a lack of information about intestinal iAs absorption. The aim of this study was to evaluate the participation of certain transporters [glucose transporters (GLUT and SGLT), organic anion transporting polypeptides (OATPs), aquaporins (AQPs), and phosphate transporters (NaPi and PiT)] in intestinal absorption of As(V) and As(III), using the Caco-2 cell line as a model of the intestinal epithelium. For this purpose, the effects of chemical inhibition and gene silencing of the transporters of interest on iAs uptake were evaluated, and also the differential expression of these transporters after treatment with iAs. The results show that chemical inhibition using rifamycin SV (OATP inhibitor), phloridzin (SGLT inhibitor), phloretin (GLUT and AQP inhibitor), and copper sulfate (AQP inhibitor) leads to a significant reduction in the apparent permeability and cellular retention of As(III). RT-qPCR indicates up-regulation of GLUT2, GLUT5, OATPB, AQP3, and AQP10 after exposure to As(III), while exposure to As(V) increases the expression of sodium-dependent phosphate transporters, especially NaPiIIb. Gene silencing of OATPB, AQP10, and GLUT5 for As(III) and NaPiIIb for As(V) significantly reduces uptake of the inorganic forms. These results indicate that these transporters may be involved in intestinal absorption of iAs.",
Arsenic,626913,"Arsenic co-exposure potentiates benzo[a]pyrene genotoxicity Abstract: Co-exposures to complex mixtures of arsenic and polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) are common in the environment. These two environmental pollutants are carcinogenic, but the nature of their molecular interactions in the induction of cancer is not well understood. Additive or synergistic interactions have been proposed to explain why arsenic, which is not a potent mutagen itself, is comutagenic with a variety of DNA-damaging agents. We have examined the genotoxicity of BaP-arsenic mixtures. We find that exposure of mouse hepatoma Hepa-1 cells to low concentrations of arsenite increases BaP–DNA adduct levels by as much as 18-fold. This effect requires the activation of BaP by cytochrome p450 1A1 (CYP1A1), although arsenite does not alter BaP-inducible CYP1A1 enzymatic activity, suggesting that arsenite acts downstream of metabolic BaP activation. Glutathione homeostasis was important in modulating the potency of arsenite. In cells depleted of reduced glutathione, arsenite increased BaP–DNA adduct formation by an even greater degree than in cells co-treated with BaP and arsenite in control medium. Although arsenic comutagenicity has been attributed to inhibition of DNA repair, arsenite treatment did not alter adduct removal kinetics in BaP-treated cells, suggesting that mechanisms upstream of DNA repair are responsible for increased adduct levels. Concentrations of arsenite and BaP that had no measurable mutagenic effect alone, increased mutation frequency at the Hprt locus by eight-fold when given in combination, demonstrating a comutagenic response between BaP and arsenite. These results provide strong support for the positive interaction between arsenic and PAH-induced cancer observed in epidemiology studies, and help to identify additional mechanistic steps likely to be involved in arsenic comutagenesis.",
Arsenic,627314,"Association between arsenic exposure and a measure of subclinical sensory neuropathy in Bangladesh Abstract: OBJECTIVES: We examined the association between arsenic exposure and peripheral neuropathy in Bangladesh, where the population has been chronically exposed to arsenic in drinking water. METHODS: We conducted a cross-sectional study of 137 subjects derived from a larger cohort. Exposure measures included individual water arsenic concentration, cumulative arsenic index, and urinary arsenic concentration taken at two time points (2001 and 2003). The primary outcome measurement was elevated vibrotactile threshold, as measured by a vibration sensitivity tester (Vibratron II). RESULTS: Arsenic exposure was associated with elevated toe vibration threshold (TVT). Specifically, cumulative arsenic index and urinary arsenic (2001) were both significantly associated with elevated TVT (P = 0.02 and P = 0.009, respectively) after adjustment for age and gender. CONCLUSIONS: Increased arsenic exposure, as measured by both cumulative and urinary measures, was associated with evidence of subclinical sensory neuropathy.",
Arsenic,1291224,"Elemental content of commercial 'ready to-feed' poultry and fish based infant foods in the UK Abstract: The study reported herein was conducted in order to establish the concentration of 20 essential and non-essential elements in a representative range of commercial infant foods in the UK targeted for infants aged between 6-12months. The primary objective of this study was to examine the nutritive values and safety of such complementary infant foods on the UK market in relation to dietary and safety guidelines. Quantitative analyses were conducted on eight different products representing four popular brands (poultry and fish based) of ready to-feed infant foods currently on sale in the UK. Six essential elements, namely: calcium, iron, magnesium, potassium, sodium and zinc were determined by ICP-OES. The concentrations of six essential trace elements (selenium, molybdenum, cobalt, copper, chromium, manganese) and eight non-essential, potentially toxic, elements (arsenic, barium, nickel, cadmium, antimony, lead, mercury, aluminium) were determined by ICP-MS due to the higher sensitivity required. The total daily intakes of essential and trace elements from the consumption of such products were then estimated, based on the results of this study, and were referenced to the Recommended Nutrient Intake (RNI) values and safety guidelines for 6-9months old children. Based on these comparisons the concentration of essential, except for potassium, and trace elements were found to be inadequate in meeting the RNI. In terms of the risk of exposure to toxicity, the concentration of toxic elements in ready to feed products analysed in this study, were not considered to be of concern. These results suggest that commercial complementary infant foods on the UK market may not contain minimum levels of minerals required for labelling declaration of micronutrient content (Commission Directive 2006/125/EC). This provides opportunities and scope for product optimisation to improve their nutritive value.",
Arsenic,1070346,"In silico and in vivo studies of an Arabidopsis thaliana gene, ACR2, putatively involved in arsenic accumulation in plants Abstract: Previously, our in silico analyses identified four candidate genes that might be involved in uptake and/or accumulation of arsenics in plants: arsenate reductase 2 (ACR2), phytochelatin synthase 1 (PCS1) and two multi-drug resistant proteins (MRP1 and MRP2) [Lund et al. (2010) J Biol Syst 18:223-224]. We also postulated that one of these four genes, ACR2, seems to play a central role in this process. To investigate further, we have constructed a 3D structure of the Arabidopsis thaliana ACR2 protein using the iterative implementation of the threading assembly refinement (I-TASSER) server. These analyses revealed that, for catalytic metabolism of arsenate, the arsenate binding-loop (AB-loop) and residues Phe-53, Phe-54, Cys-134, Cys-136, Cys-141, Cys-145, and Lys-135 are essential for reducing arsenate to arsenic intermediates (arsenylated enzyme-substrate intermediates) and arsenite in plants. Thus, functional predictions suggest that the ACR2 protein is involved in the conversion of arsenate to arsenite in plant cells. To validate the in silico results, we exposed a transfer-DNA (T-DNA)-tagged mutant of A. thaliana (mutation in the ACR2 gene) to various amounts of arsenic. Reverse transcriptase PCR revealed that the mutant exhibits significantly reduced expression of the ACR2 gene. Spectrophotometric analyses revealed that the amount of accumulated arsenic compounds in this mutant was approximately six times higher than that observed in control plants. The results obtained from in silico analyses are in complete agreement with those obtained in laboratory experiments.",
Arsenic,628567,"Hypertension and arsenic exposure in Bangladesh Abstract: A prevalence comparison of hypertension among subjects with and those without arsenic exposure through drinking water was conducted in Bangladesh to confirm or refute an earlier observation of a relation in this respect. Wells with and without present arsenic contamination were identified, and we interviewed and examined 1595 subjects who were depending on drinking water from these wells for living, all >/=30 years of age. The interview was based on a questionnaire, and arsenic exposure was estimated from the history of well-water consumption and current arsenic levels. Of the 1595 subjects studied, 1481 had a history of arsenic-contaminated drinking water, whereas 114 had not. Time-weighted mean arsenic levels (in milligrams per liter) and milligram-years per liter of arsenic exposure were estimated for each subject. Exposure categories were assessed as <0.5 mg/L, 0.5 to 1.0 mg/L, and >1.0 mg/L and alternatively as <1.0 mg-y/L, 1.0 to 5.0 mg-y/L, >5.0 but 10.0 mg-y/L, respectively. Hypertension was defined as a systolic blood pressure of >/=140 mm Hg in combination with a diastolic blood pressure of >/=90 mm Hg. Corresponding to the exposure categories, and using ""unexposed"" as the reference, the prevalence ratios for hypertension adjusted for age, sex, and body mass index were 1.2, 2.2, 2.5 and 0.8, 1.5, 2.2, 3.0, in relation to arsenic exposure in milligrams per liter and milligram-years per liter, respectively. The indicated dose-response relationships were significant (P<<0.001) for both series of risk estimates. These results suggest that arsenic exposure may induce hypertension in humans. <<0.001) for both series of risk estimates. These results suggest that arsenic exposure may induce hypertension in humans.",
Arsenic,1015904,"What is the best biomarker to assess arsenic exposure via drinking water? Abstract: Arsenic (As) is a ubiquitous element. The current WHO guideline for As in drinking water is 10 ?g/L. Furthermore, about 130 million people have only access to drinking water containing more than 10 g As/L. Although numerous studies have shown the related adverse effects of As, sensitive appropriate biomarkers are still required for studies of environmental epidemiology. A review of the literature has shown that various biomarkers are used for such research. Their limits and advantages are highlighted in this paper: (i) the detection of As or its derivatives in the blood is an indication of the dose ingested but it is not evidence of chronic intoxication. (ii) The detection of As in urine is an indispensible procedure because it is a good marker for internal dose. It has been demonstrated to correlate well for a number of chronic effects related to As levels in drinking water. However confounding factors must be taken into account to avoid misinterpretation and this may require As speciation. (iii) As in the hair and nails reflects the level of long term exposure but it is difficult to relate the level with the dose ingested. (iv) Some studies showed a correlation between urinary As and urinary and blood porphyrins. However, it is difficult to use only porphyrins as a biomarker in a population survey carried out without doing further studies. (v) Genotoxic effects are based on the characterization of these potential effects. Most studies have detected increases in DNA damage, sister chromatid exchange, micronuclei or chromosomal aberrations in populations exposed to As in drinking water. Micronuclei assay is the technique of choice to follow these populations, because it is sensitive and easy to use. To conclude, whatever epidemiological studies are, the urinary and toenail biomarkers are useful to provide indications of internal dose. Moreover, micronuclei assay can be complementary use as biomarker of early effects.",
Arsenic,628291,"Dietary arsenic affects dimethylhydrazine-induced aberrant crypt formation and hepatic global DNA methylation and DNA methyltransferase activity in rats Abstract: Cell culture studies have suggested that arsenic exposure results in decreased S-adenosylmethionine (SAM), causing DNA hypomethylation. Previously, we have shown that hepatic SAM is decreased and/or S-adenosylhomocysteine increased in arsenic-deprived rats; these rats tended to have hypomethylated DNA. To determine the effect of dietary arsenic on dimethylhydrazine (DMH)-induced aberrant crypt formation in the colon, Fisher 344 weanling male rats were fed diets containing 0, 0.5, or 50 microg As (as NaAsO2)/g. After 12 wk, dietary arsenic affected the number of aberrant crypts (p<0.02) and aberrant crypt foci (p<0.007) in the colon and the amount of global DNA methylation (p<0.04) and activity of DNA methyltransferase (DNMT) (p<0.003) in the liver. In each case, there were more aberrant crypts and aberrant crypt foci, a relative DNA hypomethylation, and increased activity of DNMT in the rats fed 50 microg As/g compared to those fed 0.5 microg As/g. The same phenomenon, an increased number of aberrant crypts and aberrant crypt foci, DNA hypomethylation, and increased DNMT tended to hold when comparing rats fed the diet containing no supplemental arsenic compared to rats fed 0.5 microg As/g. The data suggest that there is a threshold for As toxicity and that possibly too little dietary As could also be detrimental.",
Arsenic,193679,"Analyses of micronuclei in exfoliated epithelial cells from individuals chronically exposed to arsenic via drinking water in inner Mongolia, China Abstract: The groundwater in Bayingnormen (Ba Men), located in Central West Inner Mongolia, China, is naturally contaminated with arsenic at concentrations ranging from 50 microg/L to 1.8 mg/L. Various adverse health effects in this region, including cancer, have been linked to arsenic exposure via drinking water. A pilot study was undertaken to evaluate frequencies of micronuclei (MN), as measures of chromosomal alterations, in multiple exfoliated epithelial cell types from residents of Ba Men chronically exposed to arsenic via drinking water. Buccal mucosal cells, airway epithelial cells in sputum, and bladder urothelial cells were collected from 19 residents exposed to high levels of arsenic in drinking water (527.5 +/- 24 microg/l), and from 13 control residents exposed to relatively low levels of arsenic in drinking water (4.4 +/- microg/L). Analytical results from these individuals revealed that MN frequencies in the high-exposure group were significantly elevated to 3.4-fold over control levels for buccal and sputum cells, and to 2.7-fold over control for bladder cells (increases in MN frequency significant at p < .001 for buccal cells; p < .01 for sputum cells; p < .05 for bladder cells). When smokers were excluded from high-exposure and control groups the effects of arsenic were observed to be greater, although only in buccal and sputum cells; approximately 6-fold increases in MN frequency occurred in these tissues. The results indicate that residents of Ba Men chronically exposed to high levels of arsenic in drinking water reveal evidence of genotoxicity in multiple epithelial cell types; higher levels of induced MN were observed in buccal and sputum cells than in bladder cells.",
Arsenic,1017997,"Curcumin and turmeric attenuate arsenic-induced angiogenesis in ovo Abstract: Trivalent arsenic [As(III)] is currently approved by the FDA for the treatment of chronic and acute leukemias. However, As(III) has also demonstrated damaging effects on human health, including development of cardiovascular disease, diabetes, and cancer. Further, As(III) is a potent angiogenic agent. In this context, curcumin, an active ingredient in the dietary agent turmeric, has demonstrated potent antiproliferative, antiinflammatory, and antiangiogenic properties. In this report, we have shown that both curcumin and turmeric inhibit expression of vascular endothelial growth factor in HCT-116 human colon cancer cells exposed to As(III). Further, in the chicken chorioallantoic membrane assay model, treatment with low As(III) concentrations results in extensive increase in blood vessel density, which, however, is reduced in the presence of curcumin or turmeric. Collectively, the findings reported here strongly suggest that turmeric and curcumin can dramatically attenuate the process of angiogenesis induced by low As(III) concentrations.",
Arsenic,627969,"Sodium arsenite-induced inhibition of eukaryotic translation initiation factor 4E (eIF4E) results in cytotoxicity and cell death Abstract: Exposure to arsenic (As) is a risk factor for the development of diabetes, vascular diseases and cancer. Several theories have been proposed to account for the mechanisms potentially responsible for As toxicity and carcinogenesis. Currently, we have investigated whether the eukaryotic translation initiation factor 4E (eIF4E), the mRNA cap binding and rate limiting factor required for translation, is a target for As-induced cytotoxicity and cell death. We have also investigated the potential cellular mechanisms underlying the As-induced de-regulation of expression of eIF4E that are most likely responsible for the cytotoxicity and cell death induced by As. Exposure of four different human cell lines - HCT15 (colorectal adenocarcinoma), PLC/PR/5 (hepatocellular carcinoma), HeLa (cervical adenocarcinoma) and Chang (likely derived from HeLa cells) to sodium arsenite (NaAsO2) for time intervals up to 24 h resulted in a concentration-dependent cytotoxicity and cell death. All the NaAsO2-treated cells exhibited significant inhibition of eIF4E gene (protein). The potential involvement of eIF4E gene expression in the NaAsO2-induced cytotoxicity and cell death was investigated by silencing the cellular expression of the eIF4E gene by employing a small interfering RNA (SiRNA) specifically targeting the eIF4E gene's expression. The SiRNA-mediated silencing of eIF4E gene expression also resulted in significant cytotoxicity and cell death suggesting that the toxicity noticed among the NaAsO2-treated cells was probably due to the chemically induced inhibition of eIF4E gene expression. The potential involvement of inhibition of eIF4E gene expression in the NaAsO2-induced cytotoxicity and cell death was further investigated by employing transgenic cell lines overexpressing the eIF4E gene. Overexpression of the eIF4E gene in the Chinese hamster ovary cell line was protective against the NaAsO2-induced cytotoxicity and cell death. Additional studies conducted to understand the potential mechanisms responsible for NaAsO2-induced inhibition of eIF4E gene expression demonstrated that exposure to NaAsO2 resulted in transcriptional down-regulation of the eIF4E gene only in HCT-15 and HeLa cells, while in the NaAsO2-treated and PLC/PR/5 and Chang cells, the eIF4E mRNA expression level was comparable to those of the corresponding control cells. Cellular levels of ubiquitin and the process of ubiquitination were significantly higher in the NaAsO2-treated cells compared with the control cells. Immunoprecipitation of lysates obtained from the NaAsO2-treated cells and the subsequent western blot analysis of the immunoprecipitated protein(s) using the eIF4E antibody detected the presence of eIF4E protein in the immunoprecipitate suggesting possible ubiquitination of eIF4E protein in the NaAsO2-treated cells. Pre-exposure of the NaAsO2-treated cells to proteasome inhibitors blocked the inhibition of eIF4E gene expression as well as the resulting cytotoxicity and cell death. Furthermore, exposure of cells to NaAsO2 resulted in a significant inhibition of expression of the cell cycle and growth regulating gene, cyclin D1. Whether or not the inhibition of cyclin D1 in the NaAsO2-treated cells is mediated through the inhibition of eIF4E was tested by silencing the expression of eIF4E gene in the cells. Transfection of cells with SiRNA specifically targeting eIF4E gene expression resulted in a significant inhibition of cyclin D1 gene suggesting that the observed inhibition of cyclin D1 gene in the NaAsO2-treated cells is most likely mediated through inhibition of eIF4E gene. Taken together, our results indicate that the exposure of cells to NaAsO2 resulted in cytotoxicity and cell death, at least in part, due to the inhibition of eIF4E gene expression leading to diminished cellular levels of critical genes such as cyclin D1.",
Arsenic,1070360,"Effects of arsenic exposure on DNA methylation in cord blood samples from newborn babies and in a human lymphoblast cell line Abstract: BACKGROUND: Accumulating evidence indicates that in utero exposure to arsenic is associated with congenital defects and long-term disease consequences including cancers. Recent studies suggest that arsenic carcinogenesis results from epigenetic changes, particularly in DNA methylation. This study aimed to investigate DNA methylation changes as a result of arsenic exposure in utero and in vitro. METHODS: For the exposure in utero study, a total of seventy-one newborns (fifty-five arsenic-exposed and sixteen unexposed newborns) were recruited. Arsenic concentrations in the drinking water were measured, and exposure in newborns was assessed by measurement of arsenic concentrations in cord blood, nails and hair by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In the in vitro study, human lymphoblasts were treated with arsenite at 0-100 muM for two, four and eight hours (short-term) and at 0, 0.5 and 1.0 muM for eight-weeks period (long-term). DNA methylation was analyzed in cord blood lymphocytes and lymphoblasts treated with arsenite in vitro. Global DNA methylation was determined as LINE-1 methylation using combined bisulfite restriction analysis (COBRA) and total 5-methyldeoxycytidine (5MedC) content which was determined by HPLC-MS/MS. Methylation of p53 was determined at the promoter region using methylation-specific restriction endonuclease digestion with MspI and HpaII. RESULTS: Results showed that arsenic-exposed newborns had significantly higher levels of arsenic in cord blood, fingernails, toenails and hair than those of the unexposed subjects and a slight increase in promoter methylation of p53 in cord blood lymphocytes which significantly correlated with arsenic accumulation in nails (p &lt; 0.05) was observed, while LINE-1 methylation was unchanged. Short-term in vitro arsenite treatment in lymphoblastoid cells clearly demonstrated a significant global hypomethylation, determined as reduction in LINE-1 methylation and total 5-MedC content, and p53 hypermethylation (p &lt; 0.05). However, a slight LINE-1 hypomethylation and transient p53 promoter hypermethylation were observed following long-term in vitro treatment. CONCLUSIONS: This study provides an important finding that in utero arsenic exposure affects DNA methylation, particularly at the p53 promoter region, which may be linked to the mechanism of arsenic carcinogenesis and the observed increased incidence of cancer later in life.",
Arsenic,1015698,"Human health risks of Pb and As exposure via consumption of home garden vegetables and incidental soil and dust ingestion: A probabilistic screening tool Abstract: The consumption of home grown vegetables may represent a significant exposure pathway for arsenic (As) and lead (Pb) relative to direct incidental ingestion of soil, thus a probabilistic screening tool for estimating these exposures was developed using regression models relating co-located soil and home garden (HG) vegetable concentrations of Pb and As established from multiple independent studies and 2-dimensional Monte Carlo analyses. For high-quantity consumers of HG vegetables (i.e., the upper 95th percentile of consumers in the general population), the HG consumption pathway can be as significant as incidental soil and dust ingestion for inorganic As and, therefore, should be considered when developing generic health-based soil criteria in residential settings. Predicted Pb Hazard Quotient (HQ) estimates among young children resulting from HG consumption were 4- to 10-fold lower than exposures resulting from direct incidental soil and dust ingestion. The difference in soil/dust ingestion rates used to characterize young children (the 95th percentile of 202mg/d) versus a lifetime residential receptor (the 95th percentile of 30mg/d) was a primary factor contributing to the relative differences observed between HQ and incremental lifetime cancer risk (ILCR) resulting from these two exposure pathways for lead Pb and inorganic arsenic As, respectively.",
Arsenic,1341094,"Evaluation of the toxic effects of arsenite, chromate, cadmium, and copper using a battery of four bioassays Abstract: The sensitivities of four different kinds of bioassays to the toxicities of arsenite, chromate, cadmium, and copper were compared. The different bioassays exhibited different sensitivities, i.e., they responded to different levels of toxicity of each of the different metals. However, with the exception of the ?-glucosidase enzyme activity, arsenite was the most toxic compound towards all the tested organisms, exhibiting the highest toxic effect on the seeds of Lactuca, with an EC(50) value of 0.63 mg/L. The sensitivities of Lactuca and Raphanus were greater than the sensitivities of two other kinds of seeds tested. Therefore, these were the seeds appropriate for use in a seed germination assay. A high revertant mutagenic ratio (5:1) of Salmonella typhimurium was observed with an arsenite concentration of 0.1 ?g/plate, indicative of a high possibility of mutagenicity. These different results suggested that a battery of bioassays, rather than one bioassay alone, is needed as a more accurate and better tool for the bioassessment of environmental pollutants.",
Arsenic,1024764,"Gene expression changes associated with altered growth and differentiation in benzo[a]pyrene or arsenic exposed normal human epidermal keratinocytes Abstract: Both arsenic and benzo[a]pyrene (BaP) inhibit terminal differentiation and alter growth potential in normal human epidermal keratinocytes (NHEK) in vitro. To identify molecular alterations that may be involved in these cellular processes, microarray analysis was carried out on NHEK treated with BaP or arsenic. The gene expression microarray results measuring mRNA levels were as follows: (1) in total, the expression of 85 genes was induced and 17 genes was suppressed by 2.0 microm BaP. (2) Arsenic at an equitoxic dose (5.0 microm) induced the expression of 106 and suppressed 15 genes. Quantitative real-time RT-PCR was used subsequently to confirm microarray findings on selected genes involved in keratinocyte growth and differentiation pathways. These studies confirmed increased mRNA levels in NHEK by BaP of alpha-integrin binding protein 63 (AIBP63) (2.48-fold), retinoic acid- and interferon-inducible protein (IFIT5) (2.74-fold), interleukin-1 alpha (IL1A) (2.64-fold), interleukin-1 beta (IL1B) (2.84-fold) and Ras guanyl releasing protein 1 (RASGRP1) (3.14-fold). Real-time RT-PCR confirmed that arsenic increased mRNA levels of the following genes: retinoblastoma 1 (RB1) (5.4-fold), retinoblastoma-binding protein 1 (ARID4A) (6.8-fold), transforming growth factor beta-stimulated protein (TSC22D1) (6.84-fold), MAX binding protein (MNT) (2.44-fold), and RAD50 (4.24-fold). Collectively, these results indicate that these chemicals target different genes and molecular pathways involved in the regulatory processes controlling NHEK proliferation and differentiation. Mechanistic studies with a subset of genes may allow the correlation of alterations in these molecular markers with chemical-specific blocks to differentiation in NHEK.",
Arsenic,1173137,"Inorganic arsenic in drinking water and bladder cancer: A meta-analysis for dose-response assessment Abstract: Most arsenic cancer risk assessments have been based solely on epidemiological studies to characterize the dose-response relationship for arsenic-associated cancer and to perform risk calculations. However, current epidemiological evidence is too inconsistent and fraught with uncertainty regarding arsenic exposure to provide reliable estimates. This makes it hard to draw a firm conclusion about the shape and slope of the dose-response relationship from individual studies. Meta-analysis is a statistical approach to combining results across studies and offers expanded opportunities for obtaining an improved dose-response relationship. In this study, a meta-analysis of arsenic studies was conducted by combining seven epidemiological studies from different regions to get an overall dose-response relationship between the amount of arsenic intake and the excess probability of bladder cancer. Both the fixed-effect and random-effect models were used to calculate the averaged coefficient of the linear-logistic regression model. A homogeneity test was also conducted. The final product of this research is an aggregated dose-response model in the range of empirical observation of arsenic. Considering the most recent arsenic MCL (maximum contaminant level, i.e. 10microg/L), the associated bladder cancer risk (lifetime excess probability) at this MCL is 2.29 x 10-5.",
Arsenic,1022277,"Occupation and larynx and hypopharynx cancer: A job-exposure matrix approach in an international case-control study in France, Italy, Spain and Switzerland Abstract: <strong>OBJECTIVE: </strong>To investigate the effect of exposure to occupational agents on the risk of hypopharyngeal/laryngeal cancer.<br /><br /><strong>METHODS: </strong>Case-control study conducted during 1979-1982 in six centres in South Europe. An occupational history and information on exposure to non-occupational factors were collected for 1010 male cases of hypopharyngeal/ laryngeal cancer as well as for 2176 population controls. The exposure to 10 occupational agents was assessed through a job-exposure matrix. As occupational histories had been collected since 1945 major analyses were restricted to subjects aged less than 55 years (315 cases and 819 controls).<br /><br /><strong>RESULTS: </strong>Significant elevated risks adjusted for non-occupational variables (smoking, alcohol consumption and diet) and other occupational exposures were consistently found for organic solvents (odds ratio (OR) for ever-exposure: 1.7, 95% confidence interval: 1.1-2.5) and asbestos (OR: 1.6, 1.0-2.5). A significant positive trend for both probability of exposure and duration was found for exposure to solvents. A positive association between exposure to formaldehyde and laryngeal cancer was also suggested. No association was found for exposure to arsenic and compounds, chromium and compounds, and polycyclic aromatic hydrocarbons. Analyses restricted to subjects aged 55 or more did not show elevated risks, with the exception of wood dust (OR: 1.8, 1.3-2.7).<br /><br /><strong>CONCLUSIONS: </strong>In our study occupational exposure to solvents was associated with an increased risk of hypopharyngeal/laryngeal cancer. Results also provide additional evidence of an excess of risk for exposure to asbestos.",
Arsenic,1252040,"Inhibition of the orthophosphatase and pyrophosphatase activities of human alkaline-phosphatase preparations Abstract: 1. Inhibition of the pyrophosphatase and orthophosphatase activities of human liver and small-intestinal alkaline-phosphatase preparations by different classes of inhibitors has been studied. 2. Each type of substrate, pyrophosphate or orthophosphate, is a competitive inhibitor of hydrolysis of the other type. 3. l-Phenylalanine is a non-competitive inhibitor of both types of activity of the intestinal preparation, but inhibits neither activity of the liver enzyme. Arsenate is a competitive inhibitor of both activities of both preparations. For a given inhibitor, the values of K(i) are independent of the type of substrate used when measurements are made at the same pH. 4. Mg(2+) ions activate orthophosphatase but inhibit pyrophosphatase, except in very low concentrations. 5. These results are compatible with the presence in each tissue preparation of a single enzyme with one type of active centre, possessing both orthophosphatase and pyrophosphatase activities.",
Arsenic,1017805,"Oxidatively damaged DNA induced by humic acid and arsenic in maternal and neonatal mice Abstract: We measured the levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), a useful biomarker of oxidative injury, in liver (or urine) of maternal mice and their offspring, that were treated with humic acid (HA) and arsenic (As) alone, or their combination during pregnancy. A highly sensitive and specific isotope-dilution LC-MS/MS method was used for 8-oxodGuo quantification. Total arsenic accumulated in the offspring was also measured using ICP-MS. This study demonstrated, for the first time in an animal model, that HA alone treatment led to a significant increase of 8-oxodGuo levels both in liver and urine of maternal mice. No enhanced effect was observed when HA was combined with As, compared with the As alone treatment. With regard to the associated offspring, elevated levels of 8-oxodGuo and total arsenic were observed in offspring only when mother mice were treated with As and its combination with HA, but not for the HA-treated alone. It was worthy to note that the offspring from maternal combined treatment with HA and As had a significantly lower 8-oxodGuo than those of maternal treatment with As alone. This could be explained by that part of As formed complexes with HA and these macromolecules of HA-As complexes may not readily cross the placenta to the fetus, as evidenced by the lower accumulated total As observed in the offspring livers. Overall, it seems that HA may be detrimental to the maternal mice, but in the meantime it can be beneficial to the offspring by reducing free As.",
Arsenic,1337308,"History of arsenic ethers: who was Felix D'Arcet? Abstract: Williamson serendipitously discovered (1851) a new and efficient way to produce esters using ethyl iodide and potassium salts and in doing so elucidated the molecular mechanism behind ether formation. Lassaigne (1820) made the analogy between sulphovinic and phosphovinic acids and demonstrated the existence of phosphovinic acid, while Pelouze (1833) synthesised monoethyl phosphovinic acid. Finally 1848 Voegeli produced diethyl phosphovinic acid and the first neutral ester of phosphoric acid, the triethyl phosphate (TEP). The successes of Lassaigne and Pelouze in producing phosphovinic acids and Mitscherlich's theory of isomorphism fuelled the search for the vinic acids of arsenic, phosphorus neighbor in the periodic system. This short report attempts to identify the (less known) pharmacists and chemists involved in the quest for both arsenovinic acids and the neutral esters of arsenic and pyroarsenic acids.",
Arsenic,477553,"Association between occupational exposure to arsenic and neurological, respiratory and renal effects Abstract: Occupational exposure by inhalation in copper smelter is associated with several subclinical health phenomena. The respiratory tract is usually involved in the process of detoxication of inhaled noxious agents which, as arsenic, can act as inductors of oxidative stress (Lantz, R.C., Hays, A.M., 2006. Role of oxidative stress in arsenic-induced toxicity. Drug Metab. Rev. 38, 791-804). It is also known that irritating fumes affect distal bronchioles of non-ciliated, epithelial Clara cells, which secrete anti-inflammatory and immunosuppressive Clara cell protein (CC16) into the respiratory tract. The study group comprised 39 smelters employed at different workplaces in a copper foundry, matched for age and smoking habits with the control group (n=16). Subjective neurological symptoms (SNS), visual evoked potentials (VEP), electroneurographic (EneG) and electroencephalographic (EEG) results were examined in the workers and the relationships between As concentration in the air (As-Air) and urine (As-U) were assessed. Effects of exposure were expressed in terms of biomarkers: CC16 as early pulmonary biomarker and beta(2)-microglobulin (beta M-2) in urine and serum and retinol binding protein (RBP) as renal markers, measured by sensitive latex immunoassay. The concentrations of arsenic exceeded about two times the Threshold Limit Values (TLV) (0.01 mg/m(3)). The contents of lead did not exceed the TLV (0.05 mg/m(3)). Low CC16 levels in serum (12.1 mu g/l) of workers with SNS and VEP symptoms and highest level As-U (x(a) 39.0 mu g/l) were noted earliest in relation to occupational time. Moreover, those effects were associated with increased levels of urinary and serum beta M-2 and urinary RBP. Results of our study suggested the initiative key role of oxidative stress in triggering the processes that eventually lead to the subclinical effects of arsenic on the nervous system. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,2337285,"Raman spectroscopy of the arsenate minerals maxwellite and in comparison with tilasite Abstract: Maxwellite NaFe(3+)(AsO4)F is an arsenate mineral containing fluoride and forms a continuous series with tilasite CaMg(AsO4)F. Both maxwellite and tilasite form a continuous series with durangite NaAl(3+)(AsO4)F. We have used the combination of scanning electron microscopy with EDS and vibrational spectroscopy to chemically analyse the mineral maxwellite and make an assessment of the molecular structure. Chemical analysis shows that maxwellite is composed of Fe, Na and Ca with minor amounts of Mn and Al. Raman bands for tilasite at 851 and 831cm(-1) are assigned to the Raman active ?1 symmetric stretching vibration (A1) and the Raman active triply degenerate ?3 antisymmetric stretching vibration (F2). The Raman band of maxwellite at 871cm(-1) is assigned to the ?1 symmetric stretching vibration and the Raman band at 812cm(-1) is assigned to the ?3 antisymmetric stretching vibration. The intense Raman band of tilasite at 467cm(-1) is assigned to the Raman active triply degenerate ?4 bending vibration (F2). Raman band at 331cm(-1) for tilasite is assigned to the Raman active doubly degenerate ?2 symmetric bending vibration (E). Both Raman and infrared spectroscopy do not identify any bands in the hydroxyl stretching region as is expected.",
Arsenic,1359146,"Angiosarcoma of the liver: Annual occurrence and etiology in Great Britain, UK Abstract: HEEP COPYRIGHT: BIOL ABS. The annual occurrence of angiosarcoma of the liver (ASL) in Britain from 1963-1977 was studied, including clinical and occupational details for those cases agreed as ASL by a panel of histopathologists. Cases (28 men, 6 women and 1 infant girl) were agreed as ASL. The increase in the incidence of ASL observed in recent years was attributable to Thorotrast (thorium dioxide) usage (8 cases) and exposure to vinyl chloride (2 cases) in the past. In its clinical presentation and prognosis ASL resembled primary liver carcinoma, except that extrahepatic metatases were found in only 8 (23%) cases, and hemoperitoneum was more common in those cases due to Thorotrast. There is a possible increased risk of ASL in the electrical and plastics fabrication industries, but information on exposure was inadequate to implicate specific chemicals. The clinical features of 1 case was indicative of As intoxication, but medications in the other patients were not of etiological importance.",
Arsenic,1579270,Characteristics of Phosphate Adsorption-Desorption Onto Ferrihydrite: Comparison With Well-Crystalline Fe (Hydr)Oxides Abstract: ,
Arsenic,1015994,"MiADMSA reverses impaired mitochondrial energy metabolism and neuronal apoptotic cell death after arsenic exposure in rats Abstract: Arsenicosis, due to contaminated drinking water, is a serious health hazard in terms of morbidity and mortality. Arsenic induced free radicals generated are known to cause cellular apoptosis through mitochondrial driven pathway. In the present study, we investigated the effect of arsenic interactions with various complexes of the electron transport chain and attempted to evaluate if there was any complex preference of arsenic that could trigger apoptosis. We also evaluated if chelation with monoisoamyl dimercaptosuccinic acid (MiADMSA) could reverse these detrimental effects. Our results indicate that arsenic exposure induced free radical generation in rat neuronal cells, which diminished mitochondrial potential and enzyme activities of all the complexes of the electron transport chain. Moreover, these complexes showed differential responses towards arsenic. These early events along with diminished ATP levels could be co-related with the later events of cytosolic migration of cytochrome c, altered bax/bcl(2) ratio, and increased caspase 3 activity. Although MiADMSA could reverse most of these arsenic-induced altered variables to various extents, DNA damage remained unaffected. Our study for the first time demonstrates the differential effect of arsenic on the complexes leading to deficits in bioenergetics leading to apoptosis in rat brain. However, more in depth studies are warranted for better understanding of arsenic interactions with the mitochondria.",1
Arsenic,2064131,"Spatial and temporal evolutions of groundwater arsenic approximately along the flow path in the Hetao basin, Inner Mongolia Abstract: Patchy distribution of high As groundwater has normally been observed in As-affected areas. Spatial and temporal evolutions help in better understanding mechanisms of As mobilization and in developing effective strategies for ensuring drinking water safety. Four multilevel samplers were installed approximately along the groundwater flow path to investigate spatial and temporal variations in groundwater As in the Hetao basin, Inner Mongolia. Both water chemistry and groundwater level were monitored for about two years. Groundwater As concentration generally showed increasing trends, and Eh values showed decreasing trends along the flow path, indicating that As was mobilized via reductive dissolution of Fe oxides. However, in evaporation discharge area, shallow groundwater As was generally lower than those upstream and downstream. In addition to evaporation, siderite and pyrite precipitations controlled groundwater As concentrations. The negative correlations between As concentration and SIpyrite (or SIsiderite) implied that siderite and pyrite precipitations would scavenge groundwater As and lower As concentration. Temporal variation showed different trends in different locations. It may reflect replenishment of high/low As groundwater for the increase/decrease in As concentrations, resulting from water level fluctuation. The increase trends in groundwater As concentrations at depth around 15 m in the discharge areas would result from the increase in the recharge of underlying groundwater (20 m) with high As concentration due to enhanced evaporation in the seasons with high water levels. The investigation suggested that monitoring of groundwater As should be routinely carried out to ensure the drinking water safety in the As-affected areas.",
Arsenic,1024322,"Immobilization of arsenic in a tailings material by ferrous iron treatment Abstract: Weathering and internal dissolution processes in mining waste materials may mobilize elevated levels of arsenic (As), contaminating ground and surface waters. Treating the polluted waters with iron oxyhydroxides is an established remediation method. By contrast, little knowledge is available to stabilize As in source materials by treating it with Fe precipitates and, on this way, to prevent the generation of polluted waters. In the present work the efficiency of Fe(II) treatment on As immobilization in a tailings material (TM) was studied with regard to the Fe:As molar ratio, the influence of CaCO3 amendment, and the As desorption at continued intensive leaching of Fe-treated TM. Fe precipitates were created by aerobic treatment of TM with Fe(II)sulfate at several Fe:As molar ratios with or without adding CaCO3, followed by aging the Fe-treated TM. The As retention in the treated tailings was studied by 4-fold elution with water, and the As desorption kinetics was examined by suspension leaching in laboratory microcosms over 3 weeks. Fe(II) treatment of TM reduced the water-extractable total As to &lt;10 microg/L as the Fe:As molar ratio increased from 0 to 8. The water-soluble As of Fe-treated tailings could be reduced to 10-30 microg/L also under conditions of intensive leaching. Stabilizing the pH with CaCO3 resulted in consistently higher As release. The As desorption data followed the first-order kinetics in the early time stages of the desorption whereas at longer times the parabolic diffusion model was valid.",
Arsenic,1017165,"Quantitative mass spectrometry reveals the epigenome as a target of arsenic Abstract: Recent studies reveal that posttranslational modifications on chromatin proteins, especially histones, organize genomic DNA and mediate various cellular responses to environmental influences. Quantitative mass spectrometric analysis is a powerful approach to reveal these dynamic events on chromatin in a systematic manner. Here, the effects of arsenic exposure on histone epigenetic state were investigated in human UROtsa cells, and a reduction in acetylation level on several histone H3 and H4 lysine residues was detected. Furthermore, MYST1 was shown to be the major histone acetyltransferase for H4 Lys16 and protect UROtsa cells from arsenic toxicity.",
Arsenic,1020411,"Physical injury risks associated with drinking water arsenic treatment Abstract: We estimated the number of transportation deaths that would be associated with water treatment in Albuquerque to meet the EPA's recently proposed revisions of the Maximum Contaminant Level (MCL) for arsenic. Vehicle mileage was estimated for ion exchange, activated alumina, and iron coagulation/microfiltration water treatment processes to meet an MCL of 0.020 mg/L, 0.010 mg/L, 0.005 mg/L, and 0.003 mg/L. Local crash, injury, and death rates per million vehicle miles were used to estimate the number of injuries and deaths. Depending on the water treatment options chosen, we estimate that meeting an arsenic MCL of 0.005 mg/L will result in 143 to 237 crashes, 58 to 98 injuries, and 0.6 to 2.6 deaths in Albuquerque over a 70-year period, resulting in 26 to 113 years of life lost. The anticipated health benefits for Albuquerque residents from a 0.005 mg/L arsenic MCL, estimated using either a multistage Weibull or Poisson model, ranged from 3 to 80 arsenic-related bladder and lung cancer deaths prevented over a 70-year period, adding between 43 and 1,123 years of life. Whether a revised arsenic MCL increases or reduces overall loss of life in Albuquerque depends on the accuracy of EPA's cancer risk assessment. If the multistage Weibull model accurately estimates the benefits, the years of life added is comparable or lower than the anticipated years lost due to transportation associated with the delivery of chemicals, disposal of treatment waste, and operation of the water treatment system. Coagulation/microfiltration treatment will result in substantially fewer transportation deaths than either ion exchange or activated alumina.",
Arsenic,2345663,"Proteomics of arsenic stress in the gram-positive organism Exiguobacterium sp. PS NCIM 5463 Abstract: The general responses of microorganisms to environmental onslaughts are modulated by altering the gene expression pattern to reduce damage in the cell and produce compensating stress responses. The present study attempts to unravel the response of the Gram-positive Exiguobacterium sp. PS NCIM 5463 in the presence of [As(III)] and arsenate [As(V)] using comparative proteomics via two-dimension gel electrophoresis (2-DE) coupled with identification of proteins using matrix-assisted laser desorption/ionisation (MALDI-TOF/MALDI-TOF/TOF). Out of 926 Coomassie-stained proteins, 45 were differentially expressed (p?&lt;?0.05). Considering the resolution and abundance level, 24 spots (peptides) were subjected to MALDI analysis, identified and categorised into several functional categories, viz., nitrogen metabolism, energy and stress regulators, carbohydrate metabolism, protein synthesis components and others. A functional role of each protein is discussed in Exiguobacterium sp. PS 5463 under arsenic stress and validated at their transcript level using a quantitative real-time polymerase chain reaction. Unlike previous reports that unravel the responses toward arsenic stress in Gram-negative organisms, the present study identified new proteins under arsenic stress in a Gram-positive organism, Exiguobacterium sp. PS NCIM 5463, which could elucidate the physiology of organisms under arsenic stress.",
Arsenic,626994,"Induction of endogenous Nrf2/small maf heterodimers by arsenic-mediated stress in placental choriocarcinoma cells Abstract: Exposure to inorganic arsenic has been associated with various forms of cancer, nervous system pathogenesis, and vascular diseases, as well as reproductive and developmental toxicity. Here, the effect of inorganic arsenic on placental JAR choriocarcinoma cells was assessed. The nuclear protein levels of the CNC transcription factor Nrf2 were strongly induced in the presence of arsenic. Dosage response experiments showed that 0.5 microM of arsenic is sufficient to augment Nrf2 levels. The expression of the Nrf2 dimerization partners MafG and MafK appeared not to be modulated by arsenic, whereas MafF protein levels were slightly increased. Arsenic also induced the binding of endogenous Nrf2/small Maf DNA-binding complexes to a stress response element (StRE) recognition site. In addition, arsenic caused oxidative stress in the choriocarcinoma cell model as evidenced by an increase in intracellular H2O2 levels. Expression of the enzyme heme oxygenase-1 (HO-1), a known Nrf2 target gene, was upregulated by exposure of JAR cells to arsenic. These results suggest that Nrf2/small Maf heterodimers may play an important role in the response to arsenic-mediated stress in placental cells.",
Arsenic,1239886,"Binational Arsenic Exposure Survey: Methodology and Estimated Arsenic Intake from Drinking Water and Urinary Arsenic Concentrations Abstract: The Binational Arsenic Exposure Survey (BAsES) was designed to evaluate probable arsenic exposures in selected areas of southern Arizona and northern Mexico, two regions with known elevated levels of arsenic in groundwater reserves. This paper describes the methodology of BAsES and the relationship between estimated arsenic intake from beverages and arsenic output in urine. Households from eight communities were selected for their varying groundwater arsenic concentrations in Arizona, USA and Sonora, Mexico. Adults responded to questionnaires and provided dietary information. A first morning urine void and water from all household drinking sources were collected. Associations between urinary arsenic concentration (total, organic, inorganic) and estimated level of arsenic consumed from water and other beverages were evaluated through crude associations and by random effects models. Median estimated total arsenic intake from beverages among participants from Arizona communities ranged from 1.7 to 14.1 µg/day compared to 0.6 to 3.4 µg/day among those from Mexico communities. In contrast, median urinary inorganic arsenic concentrations were greatest among participants from Hermosillo, Mexico (6.2 µg/L) whereas a high of 2.0 µg/L was found among participants from Ajo, Arizona. Estimated arsenic intake from drinking water was associated with urinary total arsenic concentration (p &lt; 0.001), urinary inorganic arsenic concentration (p &lt; 0.001), and urinary sum of species (p &lt; 0.001). Urinary arsenic concentrations increased between 7% and 12% for each one percent increase in arsenic consumed from drinking water. Variability in arsenic intake from beverages and urinary arsenic output yielded counter intuitive results. Estimated intake of arsenic from all beverages was greatest among Arizonans yet participants in Mexico had higher urinary total and inorganic arsenic concentrations. Other contributors to urinary arsenic concentrations should be evaluated.",
Arsenic,1348008,"Arsenite exposure of cultured airway epithelial cells activates kappa B-dependent interleukin-8 gene expression in the absence of nuclear factor-kappa B nuclear translocation Abstract: Airway epithelial cells respond to certain environmental stresses by mounting a proinflammatory response, which is characterized by enhanced synthesis and release of the neutrophil chemotactic and activating factor interleukin-8 (IL-8). IL-8 expression is regulated at the transcriptional level in part by the transcription factor nuclear factor (NF)-kappaB. We compared intracellular signaling mediating IL-8 gene expression in bronchial epithelial cells cultured in vitro and exposed to two inducers of cellular stress, sodium arsenite (As(III)), and vanadyl sulfate (V(IV)). Unstimulated bronchial epithelial cells expressed IL-8, and exposure to both metal compounds significantly enhanced IL-8 expression. Overexpression of a dominant negative inhibitor of NF-kappaB depressed both basal and metal-induced IL-8 expression. Low levels of nuclear NF-kappaB were constitutively present in unstimulated cultures. These levels were augmented by exposure to V(IV), but not As(III). Accordingly, V(IV) induced IkappaBalpha breakdown and NF-kappaB nuclear translocation, whereas As(III) did not. However, both As(III) and V(IV) enhanced kappaB-dependent transcription. In addition, As(III) activation of an IL-8 promoter-reporter construct was partially kappaB-dependent. These data suggested that As(III) enhanced IL-8 gene transcription independently of IkappaB breakdown and nuclear translocation of NF-kappaB in part by enhancing transcription mediated by low levels of constitutive nuclear NF-kappaB.",
Arsenic,1337729,"Lightweight nanoporous metal hydroxide-rich zeotypes Abstract: Nanoporous materials have important industrial applications as molecular sieves, catalysts and in gas separation and storage. They are normally produced as moderately dense silicates (SiO(2)) and aluminosilicates making their specific capacities for the uptake and storage of gases, such as hydrogen, relatively low. Here we report the synthesis and characterization of lightweight, nanoporous structures formed from the metal hydroxide Be(OH)(2) in combination with relatively low levels of framework phosphate or arsenate. Three new zeotype structures are described, constructed mainly of Be(OH)(4) tetrahedra bridged through hydroxide into three-membered rings; these units link together to produce several previously unknown zeotype cage types and some of the most structurally complex, nanoporous materials ever discovered. These materials have very low densities between 1.12 and 1.37?g?cm(-3) and theoretical porosities of 63-68% of their total volume thereby yielding very high total specific pore volumes of up to 0.60?cm(3)?g(-1).",
Arsenic,1379202,"Treatment of arsenical keratosis with etretinate Abstract: Treatment with oral etretinate is reported in a case of arsenical keratosis with Bowen's disease. Good (80%) clearance in keratoses was obtained, which is maintained after 15 months' follow up.",
Arsenic,1339800,"Comparison of treated laterite as arsenic adsorbent from different locations and performance of best filter under field conditions Abstract: Arsenic pollution in groundwater is a worldwide concern due to its chronic effects on human health. Numerous studies have been carried out to obtain cost-effective arsenic removal method. Adsorption using natural materials or its treated forms is found to be cost-effective technology. Raw laterite (RL) or its treated form (TL) is studied recently as arsenic adsorbent for aqueous system. Laterite composition varies with geographical location and extent of lateritization. The study on effects of arsenic adsorption with varying composition of laterite is not explored yet. Four laterite samples with different compositions are examined to remove arsenic from water. These laterite samples are activated using an optimized acid followed by base treatment method in order to determine the effects of RL composition on arsenic adsorption behavior of TL. Higher iron and aluminum containing RL samples show higher arsenic adsorption behavior. Similarly, TL obtained from higher iron and aluminum containing RL sample shows the higher specific surface area (130-180m(2)g(-1)) and pore volume (0.28-0.35mLg(-1)). Two household filters using TL are deployed in arsenic affected area of Barasat, 24 Parganas (N), West Bengal, India and their performance is monitored for about a year.",
Arsenic,734920,"Arsenic-related DNA copy-number alterations in lung squamous cell carcinomas Abstract: Lung squamous cell carcinomas (SqCCs) occur at higher rates following arsenic exposure. Somatic DNA copy-number alterations (CNAs) are understood to be critical drivers in several tumour types. We have assembled a rare panel of lung tumours from a population with chronic arsenic exposure, including SqCC tumours from patients with no smoking history.<br /><br /> Fifty-two lung SqCCs were analysed by whole-genome tiling-set array comparative genomic hybridisation. Twenty-two were derived from arsenic-exposed patients from Northern Chile (10 never smokers and 12 smokers). Thirty additional cases were obtained for comparison from North American smokers without arsenic exposure. Twenty-two blood samples from healthy individuals from Northern Chile were examined to identify germline DNA copy-number variations (CNVs) that could be excluded from analysis.<br /><br /> We identified multiple CNAs associated with arsenic exposure. These alterations were not attributable to either smoking status or CNVs. DNA losses at chromosomes 1q21.1, 7p22.3, 9q12, and 19q13.31 represented the most recurrent events. An arsenic-associated gain at 19q13.33 contains genes previously identified as oncogene candidates.<br /><br /> Our results provide a comprehensive approach to molecular characteristics of the arsenic-exposed lung cancer genome and the non-smoking lung SqCC genome. The distinct and recurrent arsenic-related alterations suggest that this group of tumours may be considered as a separate disease subclass.",
Arsenic,1070469,"Cyclooxygenase-2 (COX-2) mediates arsenite inhibition of UVB-induced cellular apoptosis in mouse epidermal Cl41 cells Abstract: Inorganic arsenic is an environmental human carcinogen, and has been shown to act as a co-carcinogen with solar ultraviolet (UV) radiation in mouse skin tumor induction even at low concentrations. However, the precise mechanism of its co-carcinogenic action is largely unknown. Apoptosis plays an essential role as a protective mechanism against neoplastic development in the organism by eliminating genetically damaged cells. Thus, suppression of apoptosis is thought to contribute to carcinogenesis. It is known that cyclooxygenase-2 (COX-2) can promote carcinogenesis by inhibiting cell apoptosis under stress conditions; and our current studies investigated the potential contribution of COX-2 to the inhibitory effect of arsenite in UV-induced cell apoptosis in mouse epidermal Cl41 cells. We found that treatment of cells with low concentration (5 µM) arsenite attenuated cellular apoptosis upon UVB radiation accompanied with a co-inductive effect on COX-2 expression and nuclear factor-?B (NF?B) transactivation. Our results also showed that the COX-2 induction by arsenite and UVB depended on an NF?B pathway because COX-2 co-induction could be attenuated in either p65-deficient or p50-deficient cells. Moreover, UVB-induced cell apoptosis could be dramatically reduced by the introduction of exogenous COX-2 expression, whereas the inhibitory effect of arsenite on UVB-induced cell apoptosis could be impaired in COX-2 knockdown C141 cells. Our results indicated that COX-2 mediated the anti-apoptotic effect of arsenite in UVB radiation through an NF?B-dependent pathway. Given the importance of apoptosis evasion during carcinogenesis, we anticipated that COX-2 induction might be at least partially responsible for the co-carcinogenic effect of arsenite on UVB-induced skin carcinogenesis.",
Arsenic,2088334,Laboratory investigation of GCL performance for covering arsenic contaminated mine wastes Abstract: ,
Arsenic,1677258,"Arsenic exposure and prevalence of diabetes mellitus in Korean adults Abstract: It has been suggested that there is an association between environmental, low-level arsenic exposure and the risk of diabetes mellitus (DM), but little research has been conducted. Here, the glucose tolerance status and urinary creatinine adjusted total arsenic concentrations were analyzed in 3,602 subjects ? 20 yr of age who were registered for the Korea National Health and Nutrition Examination Survey, 2008-2009. Various demographic parameters were associated with urinary arsenic concentrations. After adjusting for these variables, urinary arsenic concentrations in subjects with DM were significantly higher than those in subjects with normal glucose tolerance and those with impaired fasting glucose (P < 0.001). Compared with the lowest quartile ( < 70.7 µg/g creatinine), the odds ratios and 95% confidence intervals for DM were 1.11 (0.73-1.68), 1.42 (0.94-2.13), and 1.56 (1.03-2.36) for urinary arsenic concentrations of 70.7 to < 117.7, 117.7 to < 193.4, and ? 193.4 µg/g creatinine, respectively, following multivariate adjustment. Furthermore, the urinary total arsenic concentration was inversely associated with the insulin secretion index, HOMA2 %B (? = -0.033, P = 0.032). These findings suggest that arsenic exposure, possibly involving beta cell dysfunction, is associated with an increased risk of DM in the Korean population.",
Arsenic,2064190,"Involvement of HIF-2?-mediated inflammation in arsenite-induced transformation of human bronchial epithelial cells Abstract: Arsenic is a well established human carcinogen that causes diseases of the lung. Some studies have suggested a link between inflammation and lung cancer; however, it is unknown if arsenite-induced inflammation causally contributes to arsenite-caused malignant transformation of cells. In this study, we investigated the molecular mechanisms underlying inflammation during neoplastic transformation induced in human bronchial epithelial (HBE) cells by chronic exposure to arsenite. The results showed that, on acute or chronic exposure to arsenite, HBE cells over-expressed the pro-inflammatory cytokines, interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1? (IL-1?). The data also indicated that HIF-2? was involved in arsenite-induced inflammation. Moreover, IL-6 and IL-8 were essential for the malignant progression of arsenite-transformed HBE cells. Thus, these experiments show that HIF-2? mediates arsenite-induced inflammation and that such inflammation is involved in arsenite-induced malignant transformation of HBE cells. The results provide a link between the inflammatory response and the acquisition of a malignant transformed phenotype by cells chronically exposed to arsenite and thus establish a previously unknown mechanism for arsenite-induced carcinogenesis.",
Arsenic,1025895,"Phenotypic analysis of Arabidopsis mutants: heavy metal stress Abstract: INTRODUCTIONArsenic (As) is a major environmental contaminant, arising from both industrial and agricultural use, and is one of the metals given top priority for remediation by the U.S. Department of Energy on the basis of its toxicity and widespread contamination. However, many of the molecular and genetic mechanisms contributing to arsenic toxicity and detoxification remain unknown in plants. The toxicity of arsenic depends on the arsenic oxidation state. The main arsenic oxidation states are As(III) and As(V), both of which are highly toxic to plants and animals. In plants, As(III) disrupts the sulfhydryl groups of proteins and induces the production of hydrogen peroxide, which leads to membrane damage, whereas As(V) uncouples phosphorylation in mitochondria and at high levels can inhibit seed germination. As described in this protocol, resistance or sensitivity to arsenic can be easily scored by measuring germination and root bending in exposed seedlings.",
Arsenic,1018971,"Transactivation of AP-1 in AP-1-luciferase reporter transgenic mice by arsenite and arsenate Abstract: Arsenic is a recognized carcinogen, which acts as a tumor promoter rather than as an initiator. Signal transduction pathways leading to activation of AP-1 and mitogen-activated protein kinases are proposed to be responsible for the tumor promotion activity by arsenic. Induction of AP-1 DNA binding activity and c-jun and c-fos expression was reported to be only observed in cells responding to arsenite, but not to arsenate. However, in this study, we found that both arsenite and arsenate could induce transactivation of AP-1 in mouse epidermal JB6 AP-1-luciferase reporter stable transfectants, P+1-1. This induction of AP-1 activity by arsenic appears to be through activation of mitogen-activated protein kinases and protein kinase C because increased AP-1 activity by arsenite could be blocked by either treatment of cells with PD98059 or overexpression of dominant negative protein kinase Ca. Furthermore, both arsenite and arsenate could induce transactivation of AP-1 in AP-1-luciferase reporter transgenic mice.",
Arsenic,711026,"Rejoinder: Arsenic exposure and prevalence of type 2 diabetes: Updated findings from the National Health Nutrition and Examination Survey, 2003-2006 Abstract: ",
Arsenic,2343481,"Effect of evolocumab or ezetimibe added to moderate- or high-intensity statin therapy on LDL-C lowering in patients with hypercholesterolemia: the LAPLACE-2 randomized clinical trial Abstract: <strong>IMPORTANCE: </strong>In phase 2 studies, evolocumab, a fully human monoclonal antibody to PCSK9, reduced LDL-C levels in patients receiving statin therapy.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the efficacy and tolerability of evolocumab when used in combination with a moderate- vs high-intensity statin.<br /><br /><strong>DESIGN, SETTING, AND PATIENTS: </strong>Phase 3, 12-week, randomized, double-blind, placebo- and ezetimibe-controlled study conducted between January and December of 2013 in patients with primary hypercholesterolemia and mixed dyslipidemia at 198 sites in 17 countries.<br /><br /><strong>INTERVENTIONS: </strong>Patients (n?=?2067) were randomized to 1 of 24 treatment groups in 2 steps. Patients were initially randomized to a daily, moderate-intensity (atorvastatin [10 mg], simvastatin [40 mg], or rosuvastatin [5 mg]) or high-intensity (atorvastatin [80 mg], rosuvastatin [40 mg]) statin. After a 4-week lipid-stabilization period, patients (n?=?1899) were randomized to compare evolocumab (140 mg every 2 weeks or 420 mg monthly) with placebo (every 2 weeks or monthly) or ezetimibe (10 mg or placebo daily; atorvastatin patients only) when added to statin therapies.<br /><br /><strong>MAIN OUTCOMES AND MEASURES: </strong>Percent change from baseline in low-density lipoprotein cholesterol (LDL-C) level at the mean of weeks 10 and 12 and at week 12.<br /><br /><strong>RESULTS: </strong>Evolocumab reduced LDL-C levels by 66% (95% CI, 58% to 73%) to 75% (95% CI, 65% to 84%) (every 2 weeks) and by 63% (95% CI, 54% to 71%) to 75% (95% CI, 67% to 83%) (monthly) vs placebo at the mean of weeks 10 and 12 in the moderate- and high-intensity statin-treated groups; the LDL-C reductions at week 12 were comparable. For moderate-intensity statin groups, evolocumab every 2 weeks reduced LDL-C from a baseline mean of 115 to 124 mg/dL to an on-treatment mean of 39 to 49 mg/dL; monthly evolocumab reduced LDL-C from a baseline mean of 123 to 126 mg/dL to an on-treatment mean of 43 to 48 mg/dL. For high-intensity statin groups, evolocumab every 2 weeks reduced LDL-C from a baseline mean of 89 to 94 mg/dL to an on-treatment mean of 35 to 38 mg/dL; monthly evolocumab reduced LDL-C from a baseline mean of 89 to 94 mg/dL to an on-treatment mean of 33 to 35 mg/dL. Adverse events were reported in 36%, 40%, and 39% of evolocumab-, ezetimibe-, and placebo-treated patients, respectively. The most common adverse events in evolocumab-treated patients were back pain, arthralgia, headache, muscle spasms, and pain in extremity (all &lt;2%).<br /><br /><strong>CONCLUSIONS AND RELEVANCE: </strong>In this 12-week trial conducted among patients with primary hypercholesterolemia and mixed dyslipidemia, evolocumab added to moderate- or high-intensity statin therapy resulted in additional LDL-C lowering. Further studies are needed to evaluate the longer-term clinical outcomes and safety of this approach for LDL-C lowering.<br /><br /><strong>TRIAL REGISTRATION: </strong>clinicaltrials.gov Identifier: NCT01763866.",
Arsenic,67664,"Comparative toxicity of arsine gas in B6C3F1 mice, Fischer 344 rats, and Syrian golden hamsters: System organ studies and comparison of clinical indices of exposure Abstract: Comparative Toxicity of Arsine Gas in B6C3F1 Mice, Fischer 344 Rats, and Syrian Golden Hamsters: System Organ Studies and Comparison of Clinical Indices of Exposure. BLAIR, P. C, THOMPSON, M. B., MORRISSEY, R. E., MOORMAN, M. P., SLOANE, R. A., AND FOWLER, B. a. (1990). Fundam. Appl. Toxicol. 14, 776–787. In order to examine possible species differences in response to arsine exposure, multiple inhalation studies consisting of acute (1-day), subacute (14- and 28-day), and subchronic (90-day) exposures to this agent were conducted using three different species of rodents. Evaluations of hematopoietic organs and alterations in the heme biosynthetic pathway were the focus of these studies. Species used were B6C3F1 mice (exposed 1, 14, or 90 days), Fischer 344 rats (exposed 14, 28, or 90 days), and Syrian Golden hamsters (exposed 28 days). All arsine exposures were at concentrations of 0.5, 2.5, or 5.0 ppm except for 90-day studies, in which concentrations were lowered to 0.025, 0.5, or 2.5 ppm. No changes in body weight gain were observed in either sex of mice or hamsters. The only decrease in body weight gain occurred in male rats exposed to 5.0 ppm arsine for 28 days. Significant exposure-related increases in relative spleen weights occurred in both sexes of mice and rats in the 0.5 (except 14-day female rats), 2.5, and 5.0 ppm exposure groups from all studies and in hamsters in the 2.5 and 5.0 ppm exposure groups. Generally, increases in relative liver weight occurred in fewer exposure groups and were of a lesser magnitude than increases in spleen weight. Other parameters affected included decreased packed cell volumes (mice, rats, and hamsters), hematol-ogy profiles (rats), and an increase in 6-aminolevulinic acid dehydratase activity in all species. Arsenic content was measured in livers of rats after 90 days of exposure. Concentrations increased in relation to atmospheric concentrations of arsine. Histopathological changes included increased hemosiderosis and extramedullary hematopoiesis in spleen and intracanalicular bile stasis (mice only) in liver. Additionally, bone marrow hyperplasia was observed in rats. Effects on other organs were not observed, suggesting that the hematopoietic system is the primary target for arsine. In conclusion, we have determined that the effects of arsine exposure upon mice, rats, and hamsters are similar. Most importantly, even though no effects on the hematopoietic system were observed following a single exposure to 0.5 ppm arsine which is 10 times the Threshold Limit Value (TLV) set by the American Conference of Governmental Industrial Hygienists, repeated exposure to 0.025 ppm (one-half the TLV) caused a significant anemia in rats.",
Arsenic,1251000,"Real-time characterization of cytotoxicity using single-cell impedance monitoring Abstract: Cellular impedance sensors have attracted great attention as a powerful characterization tool for real-time, label-free detection of cytotoxic agents. However, impedance measurements with conventional cell-based sensors that host multiple cells on a single electrode neither provide optimal cell signal sensitivity nor are capable of recording individual cell responses. Here we use a single-cell based platform to monitor cellular impedance on planar microelectrodes to characterize cellular death. In this study, individual cells were selectively patterned on microelectrodes with each hosting one live cell through ligand-mediated natural cell adhesion. Changes in cellular morphology and cell-electrode adherence were monitored after the patterned cells were treated with varying concentrations of hydrogen peroxide, sodium arsenite, and disodium hydrogen arsenate, three potent toxicants related to neurotoxicity and oxidative stress. At low toxicant concentrations, impedance waveforms acquired from individual cells showed variable responses. A time- and concentration-dependent response was seen in the averaged single-cell impedance waveform for all three toxicants. The apoptosis and necrosis characterizations were performed to validate cell impedance results. Furthermore, time constants of apoptosis and necrosis in response to toxicant exposure were analytically established using an equivalent circuit model that characterized the mechanisms of cell death.",
Arsenic,2149265,Influence of heavy metals on the activity of antioxidant enzymes in the metal resistant strains of Ochrobactrum and Bacillus sp Abstract: ,
Arsenic,628635,"Cytotoxic effects of various stressors on PC12 cells: Involvement of oxidative stress and effect of antioxidants Abstract: In order to specifically elucidate the involvement of oxidative stress, the effects of various types of stressors and antioxidants on PC12 cells were examined. In this study, the following four stressors were studied in detail: free radicals generated from 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), 4-hydroxynonenal (HNE), 7-ketocholesterol (KC), and arsenic trioxide (As2O3). Undifferentiated PC12 cells were treated with 50% lethal concentration (LC50) of these stressors, and subsequently the viability, apoptosis/necrosis ratio, reactive oxygen species (ROS) production, caspase-3 activity, and protection by antioxidants were measured to elucidate the underlying mechanisms that determine the action of these stressors on PC12 cells. The cytotoxicity did not correlate directly with the intracellular formation of ROS. For example, as compared to AAPH, As2O3 produced considerably smaller amounts of ROS at LC50. As observed in the cells incubated with As2O3, KC and HNE exerted cell toxicity, but with a moderate production of ROS. With the exception of HNE, the apoptosis/necrosis ratio of all the stressors evaluated by annexin V and propidium iodide assays increased with an increase in the incubation time at the LC50 values of these stressors. In accordance with apoptosis ratio, caspase activity was detected in the cells incubated with AAPH, As2O3, and KC, but not HNE at LC50 for 24 h. The protective effect of alpha-tocopherol, 17beta-estradiol, 2,3-dihydro-5-hydroxy-2,2-dipentyl-4,6-di-tert-butylbenzofuran (BO653), glutathione, and N-acetylcysteine (NAC) against cytotoxicity depended on the type of stressors. These antioxidants were found to be effective against the abovementioned stressors, except As2O3 against which only NAC was effective. These results suggest that the involvement of ROS and the protective effect of antioxidants depend on the type of stressors.",
Arsenic,1337504,"Exposure to heavy metals and polycyclic aromatic hydrocarbons and DNA damage in Taiwanese traffic conductors Abstract: BACKGROUND: Exposure to traffic-related air pollutants, including polycyclic aromatic hydrocarbons (PAHs) and heavy metals, has been associated with the etiology and prognosis of many illnesses. However, the specific causal agents and underlying mechanisms for different health outcomes remain unclear. The aims of this study were to assess the relations between urinary biomarkers of exposure to PAHs (1-hydroxypyrene-glucuronide, 1-OHPG) and heavy metals (cadmium, Cd; nickel, Ni; arsenic, As; lead, Pb; copper, Cu) and their interaction effect on DNA damage (8-oxo-7,8-dihydro-guanine, 8-oxodG). METHODS: We recruited 91 traffic conductors and 53 indoor office workers between May 2009 and June 2011 in Taipei, Taiwan. Post-shift urine samples from 2 consecutive days were analyzed for 1-OHPG, Cd, Ni, As, Pb, Cu and 8-oxodG. To estimate the effects from PAHs and metals on DNA damage, we constructed a linear mixed model adjusted for confounding variables. RESULTS: We found that urinary 1-OHPG and Cd levels were independent predictors of urinary 8-oxodG levels (?=0.112, p=0.015 for 1-OHPG; ?=0.138, p=0.031 for urinary Cd). The joint effect of urinary 1-OHPG and Cd levels was associated with urinary 8-oxodG levels (p=0.001). CONCLUSIONS: Co-exposure to environmental PAHs and Cd could cause oxidative DNA damage. Impact: These findings suggest that the additive interaction between exposure to environmental PAHs and Cd could enhance the burden of oxidative stress. IMPACT: These findings suggest that the additive interaction between exposure to environmental PAHs and Cd could enhance the burden of oxidative stress.",
Arsenic,1508618,"Drinking water arsenic in northern Chile: High cancer risks 40 years after exposure cessation Abstract: BACKGROUND: Millions of people worldwide are exposed to arsenic-contaminated water. In the largest city in northern Chile (Antofagasta) &gt;250,000 people were exposed to high arsenic drinking water concentrations from 1958 until 1970 when a water treatment plant was installed. Because of its unique geology, limited water sources, and good historical records, lifetime exposure and long-term latency patterns can be assessed in this area with better accuracy than in other arsenic-exposed areas worldwide. METHODS: We performed a population-based case-control study in northern Chile from October 2007 to December 2010 involving 232 lung and 306 bladder cancer cases and 640 age- and gender-matched controls, with detailed information on past exposure and potential confounders, including smoking and occupation. RESULTS: Bladder cancer odds ratios for quartiles of average arsenic concentrations in water before 1971 (&lt;11, 11-90, 91-335, and &gt;335 µg/L) were 1.00, 1.36 (95% confidence interval, 0.78 to 2.37), 3.87 (2.25 to 6.64), and 6.50 (3.69 to 11.43), respectively. Corresponding lung cancer odds ratios were 1.00, 1.27 (0.81 to 1.98), 2.00 (1.24 to 3.24), and 4.32 (2.60 to 7.17). Bladder and lung cancer odds ratios in those highly exposed in Antofagasta during 1958-70 but not thereafter were 6.88 (3.84 to 12.32) and 4.35 (2.57 to 7.36), respectively. Conclusions and Impact: The lung and bladder cancer risks that we found up to 40 years after high exposures have ended are very high, and suggest that prevention, treatment, and other mortality reduction efforts in arsenic-exposed countries will be needed for decades after exposure cessation.",
Arsenic,78471,"Arsine toxicity: chemical and mechanistic implications Abstract: Arsine (7784421) toxicity was reviewed. Properties, occurrence, and chemistry of arsine formation were presented. Arsine formation and industrial exposure depends on the occurrence and distribution of inorganic arsenic compounds and processes that can promote the conversion of inorganic arsenic (7440382)) compounds to arsine. Arsine can form as a result of metals reacting with a source of inorganic arsenic to produce the metal oxide, a process that is accompanied by the arsenic salt being reduced to arsine. The toxicological properties of arsine following acute and chronic exposure were discussed. A hypothetical exposure assessment was described that indicated that 4 hours occupational exposure to 30 parts per million (ppm) arsine would produce an arsine concentration of 0.26 millimolar (mM) in the blood. It was noted that since arsine concentrations as low as 0.1mM can induce hemolysis, critically toxic arsine exposures can occur in typical industrial settings. The major toxic effects of acute arsine exposure are hemolysis and renal dysfunction. The kidney dysfunction is attributed to the kidneys having to filter large quantities of hemoglobin produced by the hemolysis. Few studies investigating the effects of chronic (low dose) arsine exposure have been conducted in humans. One such study found evidence of anemia which was proportional to the length of arsine exposure. Erythrocytes are regarded as the primary target of arsine. Animal studies have shown that inhalation of 5 to 9ppm arsine causes significant hemolysis. The mechanism of arsine induced hemolysis has been postulated to involve formation of colloidal arsenic within the erythrocytes, production of hydrogen-peroxide within the cells, inhibition of catalase, or inhibition of sodium/potassium dependent adenosine-triphosphatase. Monitoring workers at risk for arsine exposure and managing arsine intoxication were discussed.",
Arsenic,1020916,"Low molecular weight thiols in arsenic hyperaccumulator Pteris vittata upon exposure to arsenic and other trace elements Abstract: Low molecular weight thiol-containing compounds have been reported to play an important role in metal detoxification and accumulation in some higher plants. The formation of these low molecular weight thiols in the recently discovered arsenic hyperaccumulator, Chinese Brake fern (Pteris vittata) upon exposure to arsenic and other trace metals was investigated. In addition to cysteine and glutathione, an unidentified thiol was observed in the plants exposed to arsenic, which was not found in the control. The concentration of the unidentified thiol showed a very strong and positive correlation with arsenic concentration in the leaflets. The unidentified thiol was low in rachises and undetectable in the roots for As-treated plants. Total and acid-soluble thiols were also measured and the results indicated that arsenic mainly stimulated the synthesis of acid-soluble thiol in Chinese Brake. The investigations of other trace elements (Cd, Cu, Cr, Zn, Pb, Hg, and Se) showed that these elements were not accumulated in Chinese Brake to high levels and the synthesis of the unidentified thiol in the plant was not observed. Our study suggests that the unidentified thiol was induced specifically by arsenic and the distribution patterns of the unidentified thiol and arsenic in the plant were consistent, indicating that the synthesis of this compound was related to As exposure.",
Arsenic,1373296,"Effect Of Arsenite On Cell Cycle Progression And P53 Functionality In Human Bladder Cell Line, HT1197 Abstract: Bladder cancer is one of the most important diseases associated with inorganic arsenic (iAs) exposure in view of its high prevalence and mortality rate. Experimental studies have shown that iAs exposure induces cell proliferation in the bladder of mice subchronically exposed to sodium arsenite (iAsIII). However, there is little available information on its effects on the cell cycle of bladder cells. Thus, our aim was to evaluate the effects of iAsIII on cell cycle progression and the response of p53 and p21 on the human-derived epithelial carcinoma of the bladder cell line HT1197. HT1197 cells were incubated with iAsIII (1-10 uM) for 24 h, and the cell cycle was determined by flow cytometry, p53, p21 and cyclin A levels were analyzed by Western blot. Levels of arsenicals species were analyzed by hydride generation atomic absorption spectrophotometry. Therefore, iAsIII treatment (1-10 uM) for 24 h induced a dose-dependent increase in the proportion of cells in S-phase, which reached 65% at the highest dose. A progressive reduction in cell proliferation was also observed. BrdU was incorporated to cellular DNA in an interrupted form, suggesting an incomplete DNA synthesis. The time-course of iAsIII effects (10 uM) showed an increase in p53 protein content and a transient increase in p21 protein levels accompanying the changes in S-phase. These effects correlated with iAs concentrations inside the cells, which were not able to metabolize iAs. Our findings suggest that the transient increase of p21 was unable to block CDK2/cyclin E complex activity. As a consequence, retinoblastoma is hyperphosphorylated allowing the transcription of genes regulated by the transcription factor E2F and the progression into the S-phase, staying in this phase by low levels of cyclin A. These changes will cause a deregulation in the cell cycle, promoting cancer development. Further studies are needed to ascertain the mechanisms underlying the effects of iAsIII on the G1 to S-phase transition in bladder.",
Arsenic,1381654,"Phenylarsine oxide and H2O2 plus vanadate induce reverse translocation of phorbol-ester-activated PKCbetaII Abstract: The intracellular localization of protein kinase C (PKC) is important for the regulation of its biological activity. Recently, it was reported that, whereas phorbol esters such as PMA induce prolonged translocation of PKC to the plasma membrane, with physiological stimuli, the translocation of PKC is transient and followed by rapid return to the cytoplasm. In addition, this membrane dissociation of PKC was shown to require both the kinase activity of PKC and the phosphorylation of its carboxyl terminus autophosphorylation sites. However, the detailed molecular mechanism of PKC reverse translocation remains obscure. We demonstrated that in porcine polymorphonuclear leucocytes (PMNs), phenylarsine oxide (PAO), a putative protein tyrosine phosphatase (PTPase) inhibitor, induced reverse translocation of PMA-stimulated PKCbetaII. Hydrogen peroxide (H(2)O(2)) in combination with vanadate, both of which are PTPase inhibitors, also induced reverse translocation of PKCbetaII. H(2)O(2) or vanadate alone had little effect on PMA-induced PKCbetaII translocation. Furthermore, genistein and ethanol, which are inhibitors of tyrosine kinase and phospholipase D, respectively, prevented the PKCbetaII reverse translocation induced by the PTPase inhibitors. These results indicate, for the first time, that the tyrosine phosphorylation/phospholipase D pathway may be involved in the process of membrane dissociation of PKC.",
Arsenic,1348704,INTERMOLECULAR INTERACTIONS IN THE SYSTEM OF EQUILIBRIUM CATALYTIC TRANSESTERIFICATION OF ESTERS .2. REACTION OF BORON AND ARSENIC BUTOXIDES WITH ALCOHOLS BASED ON IR SPECTROSCOPIC DATA Abstract: ,
Arsenic,2278379,"Assessment of Heavy Metals and Metalloids Toxicity in Buffaloes Fed on Forages Irrigated With Domestic Wastewater in Bhalwal, Sargodha, Pakistan Abstract: The main purpose of the present investigation was to examine if heavy metal and metalloid toxicity had occurred in grazing livestock fed with forages irrigated with sewage water. In particular the transfer of arsenic (As), selenium (Se) and molybdenum (Mo) from soil to plant and in turn to animal (buffaloes) was conducted in Bhalwal, Sargodha, Pakistan which falls under sub-tropical environmental conditions. Arsenic and Se concentrations were significantly lower in the soil but higher in the forages; however, Mo concentration in both soil and forages was higher. The correlation between soil, forage, hair and feces showed an imbalanced flow of As and Mo and a balanced flow of Se from soil to, forage and then to buffaloes. Based on the findings of the present study, the highest rates of transfer of metals were found in case of sewage water treatment and lowest rates were found in canal water treatment. As the transfer of metals depends on the bioavailability of metals, so the highest values may be due to the high rates of metals uptake by the plants. The lowest values of transfer showed that the plants may be resistant to these three metals or it may be due to the antagonistic effect of other metals present in the sewage water or soil. The high transfer rates show the plants are prone to become toxicant with time in future, which may cause hazardous effects to livestock rearing therein.",
Arsenic,1247625,"Tetra-arsenic oxide (Tetras) enhances radiation sensitivity of solid tumors by anti-vascular effect Abstract: Tetras (tetra-arsenic oxide, As(4)O(6)) is a derivative of arsenic used in Korean traditional medicine for the treatment of cancer, but its mechanism remains largely undefined. Recently, a similar arsenic derivative, diarsenic trioxide (As(2)O(3), ATO), has been shown to mediate anti-tumor activity, therefore reigniting interest in the therapeutic effect of arsenic compounds. Here we report that Tetras can effectively mediate an anti-vascular effect on tumors, leading to delay in tumor growth and increased survival. Our study demonstrates for the first time the potential use of Tetras as a radiation therapy enhancement agent for solid tumors. These findings reveal an unappreciated role of Tetras in cancer therapy and its potential application to radiotherapy in achieving local tumor control.",
Arsenic,710827,"Arsenic induces apoptosis of human umbilical vein endothelial cells through mitochondrial pathways Abstract: To clarify the molecular mechanisms through which arsenic causes injuries to blood vessels, we analyzed the effects of sodium arsenite (NaAsO(2)) on the apoptosis of human umbilical vein endothelial cells (HUVECs), mitochondrial membrane potential (Delta Psi m), intracellular reactive oxygen species (ROS), and the expression of the related genes. HUVECs apoptosis increased and Delta Psi m decreased in a dose-dependent manner following arsenic treatment. Intracellular ROS showed 2 phase alterations: a slight decrease with low levels of arsenic (5 and 10 microM) treatment; but a sharp increase at higher concentrations (>or=20 microM). The arsenic-induced cell apoptosis and intracellular ROS were blocked by the addition of the antioxidant N-acetyl-L-cysteine (NAC). The mRNAs of superoxide dismutase 2 (SOD2) and NAD(P)H:quinone oxidoreductase 1 (NQO1) increased strikingly when cells were treated with a low concentration of NaAsO(2) (5 microM) and the level of induction was decreased with higher concentrations of arsenic treatment. Based on the results, we suggest that the decrease of Delta Psi m caused by arsenic and the resulting cell apoptosis may contribute to the injuries of blood vessel in arsenism. The decrease in intracellular ROS and the increase in SOD2 and NQO1 expressions observed when HUVECs were treated with low concentration of NaAsO(2), suggest the role of the two enzymes in protecting HUVECs from injuries of arsenic exposure.",
Arsenic,1022095,"Pancreatic cancer risk and levels of trace elements Abstract: BACKGROUND AND AIMS: Knowledge on the aetiology of exocrine pancreatic cancer (EPC) is scant. The best established risk factor for EPC is tobacco smoking. Among other carcinogens, tobacco contains cadmium, a metal previously associated with an increased risk of EPC. This study evaluated the association between concentrations of trace elements in toenails and EPC risk. METHODS: The study included 118 EPC cases and 399 hospital controls from eastern Spain. Levels of 12 trace elements were determined in toenail samples by inductively coupled plasma mass spectrometry. OR and 95% CI, adjusted for potential confounders, were calculated using logistic regression. RESULTS: Significantly increased risks of EPC were observed among subjects whose concentrations of cadmium (OR 3.58, 95% CI 1.86 to 6.88; p(trend)=5×10(-6)), arsenic (OR 2.02, 95% CI 1.08 to 3.78; p(trend)=0.009) and lead (OR 6.26, 95% CI 2.71 to 14.47; p(trend)=3×10(-5)) were in the highest quartile. High concentrations of selenium (OR 0.05, 95% CI 0.02 to 0.15; p(trend)=8×10(-11)) and nickel (OR 0.27, 95% CI 0.12 to 0.59; p(trend)=2×10(-4)) were inversely associated with the risk of EPC. CONCLUSION: Novel associations are reported of lead, nickel and selenium toenail concentrations with pancreas cancer risk. Furthermore, the results confirm previous associations with cadmium and arsenic. These novel findings, if replicated in independent studies, would point to an important role of trace elements in pancreatic carcinogenesis.",
Arsenic,1579350,"Kinetics of arsenite removal by halobacteria from a highland Andean Chilean Salar Abstract: <strong>BACKGROUND: </strong>The purpose of this study was to identify arsenite-oxidizing halobacteria in samples obtained from Salar de Punta Negra, II Region of Chile. Seven bacterial isolates, numbered as isolates I to VII, grown in a culture medium with 100 ppm as NaAsO2 (As (III)) were tested. Bacterial growth kinetics and the percent of arsenite removal (PAR) were performed simultaneously with the detection of an arsenite oxidase enzyme through Dot Blot analysis.<br /><br /><strong>RESULTS: </strong>An arsenite oxidase enzyme was detected in all isolates, expressed constitutively after 10 generations grown in the absence of As (III). Bacterial growth kinetics and corresponding PAR values showed significant fluctuations over time. PARs close to 100% were shown by isolates V, VI, and VII, at different times of the bacterial growth phase; while isolate II showed PAR values around 40%, remaining constant over time.<br /><br /><strong>CONCLUSION: </strong>Halobacteria from Salar de Punta Negra showed promising properties as arsenite removers under control conditions, incubation time being a critical parameter.",
Arsenic,1247789,"Occupational cancer burden in Great Britain Abstract: A sound knowledge base is required to target resources to reduce workplace exposure to carcinogens. This project aimed to provide an objective estimate of the burden of cancer in Britain due to occupation. This volume presents extensive analyses for all carcinogens and occupational circumstances defined as definite or probable human occupational carcinogens by the International Agency for Research on Cancer. This article outlines the structure of the supplement - two methodological papers (statistical approach and exposure assessment), eight papers presenting the cancer-specific results grouped by broad anatomical site, a paper giving industry sector results and one discussing work-related cancer-prevention strategies. A brief summary of the methods and an overview of the updated overall results are given in this introductory paper. A general discussion of the overall strengths and limitations of the study is also presented. Overall, 8010 (5.3%) total cancer deaths in Britain and 13,?598 cancer registrations were attributable to occupation in 2005 and 2004, respectively. The importance of cancer sites such as mesothelioma, sinonasal, lung, nasopharynx, breast, non-melanoma skin cancer, bladder, oesophagus, soft tissue sarcoma and stomach cancers are highlighted, as are carcinogens such as asbestos, mineral oils, solar radiation, silica, diesel engine exhaust, coal tars and pitches, dioxins, environmental tobacco smoke, radon, tetrachloroethylene, arsenic and strong inorganic mists, as well as occupational circumstances such as shift work and occupation as a painter or welder. The methods developed for this project are being adapted by other countries and extended to include social and economic impact evaluation.",
Arsenic,1343613,"Partition of arsenic in soils sediments and the origin of naturally elevated concentrations in groundwater of the southern Pampa region (Argentina) Abstract: Excessive arsenic concentrations above the Argentinean and WHO guidelines for drinking water (10 ?g L?1) affects shallow aquifers of the southern Pampean Plain (Argentina) hosted in the Pampean and the Post Pampean formations (loess and reworked loess; Plio-Pleistocene–Holocene). Health problems related to high As concentrations in drinking waters are known as Endemic Regional Chronic Hydroarsenicism. Hydrochemistry of shallow groundwaters and soil geochemistry were investigated aiming to (1) understand the partition of As in the solid phase and its relationship with unacceptable As concentrations in waters, (2) identify the provision source of As to groundwaters. Only 5% of the samples had As concentrations <10 ?g L?1; in 27% As concentrations ranged from 10 to 50 ?g L?1 and in 58% it reached 60–500 ?g L?1. The coarse fraction (50–2,000 ?m) hosts about 27% of the total As in the solid phase, being positively correlated to Ba (p < 0.01; r 2 = 0.93). About 70% is included in the <2 ?m fraction and had positive correlations of As–Fe (p < 0.05; r 2 = 0.85) and As–Cr (p < 0.05; r 2 = 0.68). Soils and sediment sand fractions of vadose zones are the primary sources of As in shallow groundwater while adsorption–desorption processes, codisolution–coprecipitation, and evaporation during the dry seasons raise As concentrations in waters exceeding the guideline value for drinking water.",
Arsenic,628502,"Glutathione peroxidase and catalase modulate the genotoxicity of arsenite Abstract: The X-ray hypersensitive Chinese hamster ovary (CHO) cells, xrs-5, are also more sensitive to sodium arsenite in terms of cell growth and micronucleus induction than CHO-K1 cells. Since reactive oxygen species are suggested to be involved in arsenic toxicity, we have measured antioxidant mechanisms in xrs-5 as well as CHO-K1 cells. There were no apparent differences in the activities of superoxide dismutase, glutathione S-transferase, glutathione reductase, and the levels of glutathione between xrs-5 and CHO-K1 cells. However, the activities of glutathione peroxidase and catalase were 5.4- and 5.8-fold lower, respectively, in xrs-5 cells. The addition of catalase or glutathione peroxidase to cultures reduced the arsenite-induced micronuclei in xrs-5 cells. Whereas, simultaneous treatment with mercaptosuccinate, an inhibitor of glutathione peroxidase, and 3-aminotriazole, an inhibitor of catalase, synergistically increased the arsenite-induced micronuclei. These results suggest that both catalase and glutathione peroxidase are involved in defense against arsenite genotoxicity. The xrs-6 cells, another line of x-ray hypersensitive CHO cells, which had 1.6-fold higher catalase activity and 2.5-fold higher glutathione peroxidase activity than xrs-5 cells, were also more sensitive than CHO-K1 cells but were less sensitive than xrs-5 cells to cell growth inhibition of arsenite. Moreover, a 1.6-fold increase of glutathione peroxidase activity by selenite adaptation effectively removed the arsenite-induced micronuclei in CHO-K1 cells. These results suggest that glutathione peroxidase is more important than catalase in defending against arsenite toxicity. Our results also suggest that increasing the intracellular antioxidant level may have preventive or therapeutic effects in arsenic poisoning.",
Arsenic,627918,"An approach to elucidate potential mechanism of renal toxicity of arsenic trioxide Abstract: OBJECTIVE: To investigate arsenic trioxide's renal toxicity, we analyzed the gene-expression patterns of primary renal and human kidney cells (HEK293 cell line) following exposure to arsenic trioxide. Moreover, we examined a potential renal toxic mechanism(s) of arsenic trioxide by using a toxicity-related gene and investigated potential treatments to reduce the renal toxicity of arsenic trioxide. MATERIALS AND METHODS: Arsenic trioxide was exposed to primary renal and HEK293 cells, and the gene-expression analysis was conducted using DNA microarray. Then, reactive oxygen species inhibitors or alpha-lipoic acid were added to HEK293 cells exposed arsenic trioxide and cell viability was determined. RESULTS: Expression of HMOX1 mRNA increased in a time- and dose-dependent manner, and translation of heme oxygenase 1 protein was also induced. Arsenic trioxide-induced cytotoxicity was inhibited by reactive oxygen species inhibitors. Moreover, superoxide anion was detected in arsenic trioxide-treated HEK293 cells. alpha-Lipoic acid ameliorated arsenic trioxide-induced cytotoxicity and reduced superoxide anion production in HEK293 cells, whereas it had no effect in promyelocytic leukemia cells (HL-60 cells and NB4 cells) and myeloma cells (KMS12BM cells and U266 cells). CONCLUSIONS: Arsenic trioxide-induced renal toxicity is strongly associated with the increased expression of HMOX1, and the cytotoxic mechanisms of arsenic trioxide involves reactive oxygen species production as well as another pathway. These preliminary results suggest that alpha-lipoic acid may be a suitable agent for prevention or treatment of arsenic trioxide-induced renal toxicity.",1
Arsenic,627357,"An arsenic metallochaperone for an arsenic detoxification pump Abstract: Environmental arsenic is a world-wide health issue, making it imperative for us to understand mechanisms of metalloid uptake and detoxification. The predominant intracellular form is the highly mephitic arsenite, which is detoxified by removal from cytosol. What prevents arsenite toxicity as it diffuses through cytosol to efflux systems? Although intracellular copper is regulated by metallochaperones, no chaperones involved in conferring resistance to other metals have been identified. In this article, we report identification of an arsenic chaperone, ArsD, encoded by the arsRDABC operon of Escherichia coli. ArsD transfers trivalent metalloids to ArsA, the catalytic subunit of an As(III)/Sb(III) efflux pump. Interaction with ArsD increases the affinity of ArsA for arsenite, thus increasing its ATPase activity at lower concentrations of arsenite and enhancing the rate of arsenite extrusion. Cells are consequently resistant to environmental concentrations of arsenic. This report of an arsenic chaperone suggests that cells regulate the intracellular concentration of arsenite to prevent toxicity.",
Arsenic,1030597,"Principles and application of an in vivo swine assay for the determination of arsenic bioavailability in contaminated matrices Abstract: The assessment of arsenic (As) bioavailability from contaminated matrices is a crucial parameter for reducing the uncertainty when estimating exposure for human health risk assessment. In vivo assessment of As utilising swine is considered an appropriate model for human health risk assessment applications as swine are remarkably similar to humans in terms of physiology and As metabolism. While limited in vivo As bioavailability data is available in the literature, few details have been provided regarding technical considerations for performing in vivo assays. This paper describes, with examples, surgical, experimental design and analytical issues associated with performing chronic and acute in vivo swine assays to determine As bioavailability in contaminated soil and food.",
Arsenic,2298715,"Bt rice producing Cry1C protein does not have direct detrimental effects on the green lacewing Chrysoperla sinica Tjeder Abstract: The effects of insect-resistant genetically engineered rice producing Cry1C protein derived from Bacillus thuringiensis (Bt) on Chrysoperla sinica Tjeder (Neuroptera: Chrysopidae) were assessed in laboratory bioassays. Survival and development of C. sinica larvae were not adversely affected when the larvae were fed a diet containing purified Cry1C protein at 200?µg/g fresh weight of diet, representing a worst-case exposure scenario; in contrast, C. sinica larvae were adversely affected when the diet contained avidin or potassium arsenate. Life table parameters of C. sinica adults did not differ when the adults were fed with Bt or non-Bt rice pollen together with a 2?M sucrose solution. Life table parameters of C. sinica adults also did not differ when the adults were fed an artificial diet with or without purified Cry1C protein at a nominal concentration that was about 20 times higher than that in rice pollen; in contrast, C. sinica adults were adversely affected when the diet contained potassium arsenate. In all bioassays with lacewings, the bioactivity and stability of the Cry1C protein in the diet and Cry1C protein uptake by the lacewings were confirmed by ELISA and by bioassays with a Cry1C-sensitive lepidopteran. These results demonstrate that neither larvae nor adults of C. sinica are sensitive to Cry1C protein at concentrations higher than those encountered in the field, demonstrating that the growing of Bt rice producing Cry1C protein is unlikely to pose a risk to C. sinica. Environ Toxicol Chem © 2014 SETAC.",
Arsenic,1519096,"Ferrate(VI)-Induced Arsenite and Arsenate Removal by In Situ Structural Incorporation into Magnetic Iron(III) Oxide Nanoparticles Abstract: We report the first example of arsenite and arsenate removal from water by incorporation of arsenic into the structure of nanocrystalline iron(III) oxide. Specifically, we show the capability to trap arsenic into the crystal structure of ?-Fe2O3 nanoparticles that are in situ formed during treatment of arsenic-bearing water with ferrate(VI). In water, decomposition of potassium ferrate(VI) yields nanoparticles having core-shell nanoarchitecture with a ?-Fe2O3 core and a ?-FeOOH shell. High-resolution X-ray photoelectron spectroscopy and in-field (57)Fe Mössbauer spectroscopy give unambiguous evidence that a significant portion of arsenic is embedded in the tetrahedral sites of the ?-Fe2O3 spinel structure. Microscopic observations also demonstrate the principal effect of As doping on crystal growth as reflected by considerably reduced average particle size and narrower size distribution of the &quot;in-situ&quot; sample with the embedded arsenic compared to the &quot;ex-situ&quot; sample with arsenic exclusively sorbed on the iron oxide nanoparticle surface. Generally, presented results highlight ferrate(VI) as one of the most promising candidates for advanced technologies of arsenic treatment mainly due to its environmentally friendly character, in situ applicability for treatment of both arsenites and arsenates, and contrary to all known competitive technologies, firmly bound part of arsenic preventing its leaching back to the environment. Moreover, As-containing ?-Fe2O3 nanoparticles are strongly magnetic allowing their separation from the environment by application of an external magnet.",
Arsenic,1327298,"Induction of vascular endothelial growth factor expression and hypoxia-inducible factor 1alpha protein by the oxidative stressor arsenite Abstract: Recent evidence suggests that vascular endothelial growth factor (VEGF) expression is up-regulated by oxidative stressors through activation of hypoxia-inducible Factor 1 (HIF-1). To investigate whether this is a general phenomenon, we studied the effects of the sulfhydryl reagent arsenite on VEGF expression in human ovarian cancer cells. Arsenite potently induces the production of reactive oxygen species (ROS) in several cell systems and directly interacts with sulfhydryl groups of cellular thiols. We report that arsenite induces VEGF mRNA and protein levels in normoxic H134 and OVCAR-3 cells. Arsenite also increases HIF-1alpha protein levels, suggesting a role for HIF-1 in the induction of VEGF expression. Pretreatment with the ROS inhibitors catalase and mannitol attenuated arsenite-induced ROS production, but did not affect induction of VEGF mRNA and HIF-1alpha protein. In contrast, pretreatment with the thiol antioxidants glutathione or N-acetylcysteine completely abrogated both effects, whereas a potentiation was observed by depletion of intracellular glutathione. These results demonstrate that arsenite-induced VEGF mRNA and HIF-1alpha protein expression is independent of increased ROS production but critically regulated by the cellular reduced glutathione content. In addition, these data suggest the involvement of a thiol-sensitive mechanism in the regulation of VEGF mRNA expression and HIF-1alpha protein in human ovarian cancer cells.",
Arsenic,1519052,"Treatment patterns, risk factor control and functional capacity in patients with cardiovascular and chronic kidney disease in the cardiac rehabilitation setting Abstract: BackgroundChronic kidney disease (CKD) is a frequent comorbidity among elderly patients and those with cardiovascular disease. CKD carries prognostic relevance. We aimed to describe patient characteristics, risk factor management and control status of patients in cardiac rehabilitation (CR), differentiated by presence or absence of CKD.Design and methodsData from 92,071 inpatients with adequate information to calculate glomerular filtration rate (GFR) based on the Cockcroft-Gault formula were analyzed at the beginning and the end of a 3-week CR stay. CKD was defined as estimated GFR &lt;60?ml/min/1.73?m(2).ResultsCompared with non-CKD patients, CKD patients were significantly older (72.0 versus 58.0 years) and more often had diabetes mellitus, arterial hypertension, and atherothrombotic manifestations (previous stroke, peripheral arterial disease), but fewer were current or previous smokers had a CHD family history. Exercise capacity was much lower in CKD (59 vs. 92 Watts). Fewer patients with CKD were treated with percutaneous coronary intervention (PCI), but more had coronary artery bypass graft (CABG) surgery.Patients with CKD compared with non-CKD less frequently received statins, acetylsalicylic acid (ASA), clopidogrel, beta blockers, and angiotensin converting enzyme (ACE) inhibitors, and more frequently received angiotensin receptor blockers, insulin and oral anticoagulants. In CKD, mean low density lipoprotein cholesterol (LDL-C), total cholesterol, and high density lipoprotein cholesterol (HDL-C) were slightly higher at baseline, while triglycerides were substantially lower. This lipid pattern did not change at the discharge visit, but overall control rates for all described parameters (with the exception of HDL-C) were improved substantially. At discharge, systolic blood pressure (BP) was higher in CKD (124 versus 121?mmHg) and diastolic BP was lower (72 versus 74?mmHg). At discharge, 68.7% of CKD versus 71.9% of non-CKD patients had LDL-C &lt;100?mg/dl. Physical fitness on exercise testing improved substantially in both groups.When the Modification of Diet in Renal Disease (MDRD) formula was used for CKD classification, there was no clinically relevant change in these results.ConclusionWithin a short period of 3-4 weeks, CR led to substantial improvements in key risk factors such as lipid profile, blood pressure, and physical fitness for all patients, even if CKD was present.",
Arsenic,2149364,Reactive transport modelling of weathering processes in intensely stratified mine tailings Abstract: ,
Arsenic,1017429,"Antiapoptotic efficacy of folic acid and vitamin B(12) against arsenic-induced toxicity Abstract: Earlier, we proposed that the ability of folic acid and vitamin B(12) to preserve systemic and mitochondrial function after short-term exposure to arsenic may prevent further progression to more permanent injury and pathological changes leading to cell death. To elucidate its mechanism, the present study examined the antiapoptotic efficacy of folic acid and vitamin B(12) against short-term arsenic exposure-induced hepatic mitochondria oxidative stress and dysfunction. Sixteen to eighteen weeks old male albino rats weighing 140-150 × g were divided into five groups: Control (A), Arsenic-treated (B), Arsenic + folic acid (C), Arsenic +vitamin B(12) (D), and Arsenic + folic acid + vitamin B(12) (E). Data generated indicated that folic acid and vitamin B(12) separately or in combination can give significant protection against alterations in oxidative stress and apoptotic marker parameters and downstream changes in mitochondria, namely pro-oxidative (NO, TBARS, OH(-)) and antioxidative defense (SOD, CAT, GSH) markers, iNOS protein expression, mitochondrial swelling, cytochrome c oxidase and Ca(2+)-ATPase activity, Ca(2+) content, caspase-3 activity. Additionally, results of hepatic cell DNA fragmentation, arsenic load of blood, hepatic tissue and urine, and histological observations, all strongly support that both these supplements have efficacy in preventing apoptotic changes and cellular damage. As the mechanisms of actions of both of these supplements are methylation related, a combined application was more effective. Results further reveal new molecular targets through which folic acid and vitamin B(12) separately or in combination work to alleviate one critical component of arsenic-induced liver injury: mitochondria dysfunction. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.",
Arsenic,1070466,"Heavy metal contamination in a school vegetable garden in Johannesburg Abstract: Background. Feeding schemes based on school garden produce have been proposed as an effective solution to food insecurity and hunger among learners in South Africa. However, few studies have looked at the potential contamination of school food gardens when situated near mine tailing dams. Objectives. The aim of the study was to evaluate the potential heavy metal contamination in a school vegetable garden in Johannesburg. Methods. Twenty soil samples were collected from the study school and a comparison school. Surface and deep (±10 cm beneath the surface) soil samples were analysed using X-ray fluorescence for levels of arsenic, chromium, copper, lead and zinc. Thirteen vegetables samples were collected from the school garden, and compared with six samples from a national retailer and four obtained from a private organic garden. The heavy metal concentrations of the vegetable samples were analysed in the laboratories of the South African Agricultural Research Council. Results. High levels of arsenic were found in the school soil samples, and elevated concentrations of lead and mercury in the school vegetables. Calculation of the estimated daily intake for a child of 30 kg however, indicated that levels of lead, mercury and arsenic in vegetables were within acceptable limits. However, the levels of lead in the vegetable samples were high across all three sites. Conclusion. Further investigation and research should be undertaken to assess the source/s and extent of public exposure to heavy metals in vegetables in South Africa.",
Arsenic,40882,"Design of an epidemiologic study of drinking water arsenic exposure and skin and bladder cancer risk in a U S population Abstract: Ingestion of arsenic-contaminated drinking water is associated with an increased risk of several cancers, including skin and bladder malignancies; but it is not yet clear whether such adverse effects are present at levels to which the U.S. population is exposed. In New Hampshire, detectable levels of arsenic have been reported in drinking water supplies throughout the state. Therefore, we have begun a population-based epidemiologic case-control study in which residents of New Hampshire diagnosed with primary squamous cell (n = 900) and basal cell (n = 1200) skin cancers are being selected from a special statewide skin cancer incidence survey; patients diagnosed with primary bladder cancers (n = 450) are being identified through the New Hampshire State Cancer Registry. Exposure histories of these patients will be compared to a control group of individuals randomly selected from population lists (n = 1200). Along with a detailed personal interview, arsenic and other trace elements are being measured in toenail clipping samples using instrumental neutron activation analysis. Household water samples are being tested on selected participants using a hydride generation technique with high-resolution inductively coupled plasma mass spectrometry. In the first 793 households tested arsenic concentrations ranged from undetectable (0.01 microgram/l) to 180 microgram/l. Over 10% of the private wells contained levels above 10 microgram/l and 2.5% were above 50 microgram/l. Based on our projected sample size, we expect at least 80% power to detect a 2-fold risk of basal cell or squamous cell skin cancer or bladder cancer among individuals with the highest 5% toenail concentrations of arsenic.",
Arsenic,1579317,"Stable groundwater quality in deep aquifers of Southern Bangladesh: The case against sustainable abstraction Abstract: In forty six wells &gt;150m deep, from across the arsenic-polluted area of south-central Bangladesh, groundwater composition remained unchanged between 1998 and 2011. No evidence of deteriorating water quality was found in terms of arsenic, iron, manganese, boron, barium or salinity over this period of 13years. These deep tubewells have achieved operating lives of more than 20years with minimal institutional support. These findings confirm that tubewells tapping the deep aquifers in the Bengal Basin provide a safe, popular, and economic, means of arsenic mitigation and are likely to do so for decades to come. Nevertheless, concerns remain about the sustainability of a resource that could serve as a source of As-safe water to mitigate As-pollution in shallower aquifers in an area where tens of millions of people are exposed to dangerous levels of arsenic in well water. The conjunction of the stable composition in deep groundwater and the severe adverse health effects of arsenic in shallow groundwater lead us to challenge the notion that strong sustainability principles should be applied to the management of deep aquifer abstraction in Bangladesh is, the notion that the deep groundwater resource should be preserved for future generations by protecting it from adverse impacts, probably of a minor nature, that could occur after a long time and might not happen at all. Instead, we advocate an ethical approach to development of the deep aquifer, based on adaptive abstraction management, which allows possibly unsustainable exploitation now in order to alleviate crippling disease and death from arsenic today while also benefiting future generations by improving the health, education and economy of living children.",
Arsenic,2337141,"Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method Abstract: A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs) followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V) after oxidation of As(III) to As(V) using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III) was calculated by subtracting the concentration of As(V) from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD) of arsenate were 175 (for 350mL of sample solution), 0.028 mu g mL(-1), 0.090-4.0 mu g mL(-1), and 2.8% (for 2.0 mu g mL(-1), n = 7), respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.",
Arsenic,1345679,"Differential induction of podocyte heat shock proteins by prolonged single and combination toxic metal exposure Abstract: Cadmium, mercury, and arsenite are among the most abundant toxic metals (TM) in our environment, and chronic TM exposure leads to injury to the kidney's glomerular filtration barrier. The small heat shock protein hsp25, highly expressed in glomerular podocytes, is induced during development of experimental nephrotic syndrome, and hsp25 overexpression can protect cultured podocytes from injury. Because little is known about the effect of multiple TM on podocytes, we measured the response of cultured podocytes to prolonged exposures to single and multiple TM. Podocyte viability declined by approximately 50% after 3 days of treatment with 20 microM cadmium, mercury, or arsenite, and 40 microM of any of these metals was lethal. The toxicity of equimolar concentrations of two or all three metals in combination was significantly altered compared to individual metal treatments. Single TM treatments induced only modest increases in the amounts of hsp25, alphaB-crystallin, and inducible hsp70. Toxic metal combinations induced greater stress protein accumulation, especially arsenite + cadmium or arsenite + cadmium + mercury treatments, the TM mixtures with the lowest toxicity. All TM treatments caused a rapid and sustained increase in hsp25 phosphorylation. The intracellular accumulation of cadmium was greater and that of mercury was less in cells treated with TM combinations than in cells treated with a single TM. Our results showed that multiple TM effects on podocyte viability were neither additive nor synergistic and that induction of heat shock proteins correlated with increased resistance to TM injury, suggesting that induction of small heat shock proteins may play an important role in preventing TM-induced podocyte injury.",1
Arsenic,1356863,"Induction Of Oxidative Stress In Response To Ingestion Of Lead, Cadmium And Arsenic Mixtures Abstract: Human populations are commonly exposed to mixtures of chemicals. To date, relatively few studies have examined potential interactive effects using a statistical factorial design. Multiple drinking water studies were performed to test the hypothesis that exposure to arsenic, lead, or cadmium (or their combinations) for 30, 90, or 180 days at lowest-observed-effect levels (LOELs) results in increased levels of oxidative stress in the kidney, which is a target organ for trace element-induced toxicity. Male Sprague-Dawley rats were exposed to lead, cadmium, arsenic, or mixtures of these three trace elements for 30, 90, or 180 days via drinking water. Oxidative stress levels (as measured by increases in kidney carbonyls) were generally increased at 30 days and decreased at 90 and 180 days. At 30 and 180 days, cadmium appeared to attenuate carbonyl increases among mixture groups. Among all treatment groups, increases in kidney carbonyls were lowest among the PbxCdxAs group at all three timepoints. Cellular adaptation to trace element-induced oxidative stress is suggested by the attenuation of increases in kidney carbonyls at the 90 and 180 day timepoints. Statistically significant increases in kidney glutathione levels (measured as nonprotein thiols) were measured after 30 and 180 days of exposure among most treatment groups, with some of the greatest increases measured among the four combination groups at the 30 day timepoint (96%-145% increase) and the 180 day timepoint (20%-70% increase). In contrast, kidney non-protein thiols were statistically significantly decreased in 4 of 7 treatment groups after 90 days of exposure (28%-33% decrease). These data demonstrate that low-level exposure to trace elements or their mixtures results in measurable increases in oxidative stress and upregulation of cellular defensive mechanisms.",
Arsenic,1017895,"Exposure and risk assessment for aluminium and heavy metals in Puerh tea Abstract: As the consumption of Puerh tea is booming because of its multiple health-promoting effects, the possible health risks resulting from long-term exposure to metals contained in this tea need to be evaluated. To assess the human risk associated with drinking Puerh tea, concentrations of aluminium, lead, cadmium, mercury, zinc, copper and arsenic were determined in samples of Puerh tea, tea leaves from the plants, and planted soil collected from the Yunnan province, China. Site-specific exposure parameters such as body weight and consumption rate of Puerh tea were investigated in Kunming and Puer cities using face-to-face surveys. Health risks were evaluated for the inhabitants of Kunming and Puer cities by gender and by age groups. Although the Puerh tea plant easily absorbs aluminium from soil, the concentrations of Al and six other elements in Puerh tea were all far below the safety concentration limits of China. Both the HQ (Hazard Quotient) values for single elements and the HI (Hazard Index) value for all seven elements were far below one, indicating no non-carcinogenic risks from these seven elements for inhabitants of Kunming and Puer under the current consumption rates of Puerh tea. However, probabilistic estimation of carcinogenic risk shows that the 95th percentile carcinogenic rate of arsenic in Puerh tea approaches the accepted risk level of 10(-4) for the highest exposure group. Therefore, the arsenic in Puerh tea is of concern.",
Arsenic,711018,"Prolonged inorganic arsenite exposure suppresses insulin-stimulated AKT S473 phosphorylation and glucose uptake in 3T3-L1 adipocytes: Involvement of the adaptive antioxidant response Abstract: There is growing evidence that chronic exposure of humans to inorganic arsenic, a potent environmental oxidative stressor, is associated with the incidence of type 2 diabetes (T2D). One critical feature of T2D is insulin resistance in peripheral tissues, especially in mature adipocytes, the hallmark of which is decreased insulin-stimulated glucose uptake (ISGU). Despite the deleterious effects of reactive oxygen species (ROS), they have been recognized as a second messenger serving an intracellular signaling role for insulin action. Nuclear factor erythroid 2-related factor 2 (NRF2) is a central transcription factor regulating cellular adaptive response to oxidative stress. This study proposes that in response to arsenic exposure, the NRF2-mediated adaptive induction of endogenous antioxidant enzymes blunts insulin-stimulated ROS signaling and thus impairs ISGU. Exposure of differentiated 3T3-L1 cells to low-level (up to 2?M) inorganic arsenite (iAs(3+)) led to decreased ISGU in a dose- and time-dependent manner. Concomitant to the impairment of ISGU, iAs(3+) exposure significantly attenuated insulin-stimulated intracellular ROS accumulation and AKT S473 phosphorylation, which could be attributed to the activation of NRF2 and induction of a battery of endogenous antioxidant enzymes. In addition, prolonged iAs(3+) exposure of 3T3-L1 adipocytes resulted in significant induction of inflammatory response genes and decreased expression of adipogenic genes and glucose transporter type 4 (GLUT4), suggesting chronic inflammation and reduction in GLUT4 expression may also be involved in arsenic-induced insulin resistance in adipocytes. Taken together our studies suggest that prolonged low-level iAs(3+) exposure activates the cellular adaptive oxidative stress response, which impairs insulin-stimulated ROS signaling that is involved in ISGU, and thus causes insulin resistance in adipocytes.",
Arsenic,626982,"Sodium arsenite accelerates TRAIL-mediated apoptosis in melanoma cells through upregulation of TRAIL-R1/R2 surface levels and downregulation of cFLIP expression Abstract: AP-1/cJun, NF-?B and STAT3 transcription factors control expression of numerous genes, which regulate critical cell functions including proliferation, survival and apoptosis. Sodium arsenite is known to suppress both the IKK-NF-?B and JAK2-STAT3 signaling pathways and to activate the MAPK/JNK-cJun pathways, thereby committing some cancers to undergo apoptosis. Indeed, sodium arsenite is an effective drug for the treatment of acute promyelocytic leukemia with little nonspecific toxicity. Malignant melanoma is highly refractory to conventional radio- and chemotherapy. In the present study, we observed strong effects of sodium arsenite treatment on upregulation of TRAIL-mediated apoptosis in human and mouse melanomas. Arsenite treatment upregulated surface levels of death receptors, TRAIL-R1 and TRAIL-R2, through increased translocation of these proteins from cytoplasm to the cell surface. Furthermore, activation of cJun and suppression of NF-?B by sodium arsenite resulted in upregulation of the endogenous TRAIL and downregulation of the cFLIP gene expression (which encodes one of the main anti-apoptotic proteins in melanomas) followed by cFLIP protein degradation and, finally, by acceleration of TRAILinduced apoptosis. Direct suppression of cFLIP expression by cFLIP RNAi also accelerated TRAIL-induced apoptosis in these melanomas, while COX-2 suppression substantially increased levels of both TRAIL-induced and arsenite-induced apoptosis. In contrast, overexpression of permanently active AKTmyr inhibited TRAIL-mediated apoptosis via downregulation of TRAIL-R1 levels. Finally, AKT overactivation increased melanoma survival in cell culture and dramatically accelerated growth of melanoma transplant in vivo, highlighting a role of AKT suppression for effective anticancer treatment",
Arsenic,2298693,"Catalysis of CO2 Absorption in Aqueous Solution by Inorganic Oxoanions and their Application to Post Combustion Capture Abstract: To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, Post Combustion Capture (PCC) using amine-based solvents to chemically absorb CO2 has been extensively developed. From an infrastructure viewpoint, the faster the absorption of CO2, the smaller the absorber required. The use of catalysts for this process has been broadly studied. In this manuscript, a study of the catalytic efficiencies of inorganic oxoanions such as arsenite, arsenate, phosphite, phosphate and borate is described. The kinetics of the accelerated CO2 absorption at 25°C was investigated using stopped-flow spectrophotometry. The catalytic rate constants of these anions for the reaction of CO2 with H2O were determined to be 137.7(3), 30.3(7), 69(2), 32.7(9) and 13.66(7) M(-1)s(-1), respectively. A new mechanism for the catalytic reaction of oxoanions with CO2 has also been proposed. The applicability of these catalysts to PCC was further studied by simulation of the absorption process under PCC conditions using their experimental catalytic rate constants. Arsenite and phosphite were confirmed to be the best catalysts for CO2 capture. However, considering the toxicological effect of arsenic and the oxidative instability of phosphite, phosphate would be the most promising inorganic catalyst for PCC process from the series of inorganic oxoanions studied.",
Arsenic,2064250,Synthesis and reactivity of metal complexes with acyclic (amino)(ylide)carbene ligands Abstract: No cycle required: The straightforward synthesis of acyclic (amino)(ylide)carbene gold complexes was achieved by reaction of isocyanide gold complexes with phosphorus and arsenic ylides as well as electron-rich olefins. Their ability to form bimetallic species and to act as ligand-transfer reagents has also been established.,
Arsenic,1021681,"miR-190-mediated downregulation of PHLPP contributes to arsenic-induced Akt activation and carcinogenesis Abstract: The role of trivalent arsenic (As(3+)) on the regulation of the recently identified noncoding small RNAs, mainly microRNAs, has not been explored so far. In the present study, we provide evidence showing that As(3+) is a potent inducer for the expression of miR-190 in human bronchial epithelial cells. The induction of miR-190 by As(3+) is concentration dependent and associated with the expression of the host gene of miR-190, talin 2, a gene encoding a high-molecular-weight cytoskeletal protein. The elevated level of miR-190 induced by As(3+) is capable of downregulating the translation of the PH domain leucine-rich repeat protein phosphatase (PHLPP), a negative regulator of Akt signaling. Such a downregulation is occurred through direct interaction of the miR-190 with the 3'-UTR region of the PHLPP mRNA, leading to a diminished PHLPP protein expression and consequently, an enhanced Akt activation and expression of vascular endothelial growth factor, an Akt-regulated protein. Overexpression of miR-190 itself is able to enhance proliferation and malignant transformation of the cells as determined by anchorage-independent growth of the cells in soft agar. Accordingly, the data presented suggest that induction of miR-190 is one of the key mechanisms in As(3+)-induced carcinogenesis.",
Arsenic,2347694,"Spatiotemporal distribution of airborne particulate metals and metalloids in a populated arid region Abstract: A statistical analysis of data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network of aerosol samplers has been used to study the spatial and temporal concentration trends in airborne particulate metals and metalloids for southern Arizona. The study region is a rapidly growing area in southwestern North America characterized by high fine soil concentrations (among the highest in the United States), anthropogenic emissions from an area within the fastest growing region in the United States, and a high density of active and abandoned mining sites. Crustal tracers in the region are most abundant in the summer (April - June) followed by fall (October - November) as a result of dry meteorological conditions which favor dust emissions from natural and anthropogenic activity. A distinct day-of-week cycle is evident for crustal tracer mass concentrations, with the greatest amplitude evident in urban areas. There have been significant reductions since 1988 in the concentrations of toxic species that are typically associated with smelting and mining. Periods with high fine soil concentrations coincide with higher concentrations of metals and metalloids in the atmosphere, with the enhancement being higher at urban sites.",
Arsenic,1256740,"The control of histone methylation and gene expression by oxidative stress, hypoxia and metals Abstract: The harmful consequences of carcinogenic metals, such as nickel, arsenic and chromium, are thought to be in part due to their ability to induce oxidative stress. The ubiquity of oxidative stress in biological systems has made it a fairly obvious culprit in causing cellular damage and/or development of disease. However, the full extent of oxidative stress-induced damage is not limited to its direct effects on cellular components, such as lipids, proteins and DNA, but may extend to its ability to alter gene expression. Gene expression regulation is an important component of cellular and/or tissue homeostasis, and its alteration can have detrimental consequences. Therefore, a growing amount of interest is being paid to understanding how oxidative stress can influence gene expression. Oxidative stress-induced epigenetic dysregulation in the form of post-translational histone modifications, in particular, is a popular topic of research. This review will therefore primarily focus on discussing the role of oxidative stress and hypoxia on histone methylation and/or gene expression alterations. The sources of oxidative stress discussed here are carcinogenic metals, such as, nickel, arsenic and chromium.",
Arsenic,1519141,Prediction of the As(III) and As(V) Abatement Capacity of Zea mays Cob Powder: ANN Modelling Abstract: ,
Arsenic,2298727,"Methods of preventing bacterial sepsis and wound complications after liver transplantation Abstract: <strong>BACKGROUND: </strong>Bacterial sepsis and wound complications after liver transplantation increase mortality, morbidity, or hospital stay and are likely to increase overall transplant costs. All liver transplantation patients receive antibiotic prophylaxis. This is an update of our 2008 Cochrane systematic review on the same topic in which we identified seven randomised clinical trials.<br /><br /><strong>OBJECTIVES: </strong>To assess the benefits and harms of different methods aimed at preventing bacterial sepsis and wound complications in people undergoing liver transplantation.<br /><br /><strong>SEARCH METHODS: </strong>We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and Science Citation Index Expanded to February 2013.<br /><br /><strong>SELECTION CRITERIA: </strong>We included only randomised clinical trials irrespective of language or publication status. We excluded quasi-randomised and other observational studies for assessment of benefits, but not for harms.<br /><br /><strong>DATA COLLECTION AND ANALYSIS: </strong>Two review authors collected the data independently. We calculated the risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) using fixed-effect and the random-effects models based on available-case analysis.<br /><br /><strong>MAIN RESULTS: </strong>We identified only seven trials for inclusion, including 614 participants. Only one trial was of low risk of bias risk. Overall, the quality of evidence was very low. There were five comparisons in the seven trials: selective bowel decontamination versus inactive control; selective bowel decontamination versus prebiotics with probiotics; selective bowel decontamination versus prebiotics; prebiotics with probiotics versus prebiotics; and granulocyte-colony stimulating factor (G-CSF) versus control. Four trials compared selective bowel decontamination versus placebo or no treatment. In one trial, participants were randomised to selective bowel decontamination, active lactobacillus with fibres (probiotic with prebiotic), or to inactivated lactobacillus with fibres (prebiotic). In one trial, active lactobacillus with fibres (probiotic with prebiotic) was compared with inactive lactobacillus with fibres (prebiotic). In the remaining trial, different doses of G-CSF and placebo were compared. There was no trial comparing different antibiotic prophylactic regimens in people undergoing liver transplantation. Most trials included adults undergoing elective liver transplantation. There was no significant difference in proportion of people who died or required retransplantation between the intervention and control groups in any of the five comparison groups. MortalityThere were no differences between 190 participants (three trials); 5/87 (adjusted proportion: 6.2%) in selective bowel decontamination group versus 7/103 (6.8%) in inactive control group; RR 0.91 (95% CI 0.31 to 2.72); 63 participants (one trial); 0/32 (0%) in selective bowel decontamination group versus 0/31 (0%) in prebiotics with probiotics group; RR - not estimable; 64 participants (one trial); 0/32 (0%) in selective bowel decontamination group versus 0/32 (0%) in prebiotics group; RR - not estimable; 129 participants (two trials); 0/64 (0%) in prebiotics with probiotics group versus 0/65 (0%) in prebiotics group; RR - not estimable; and 194 participants (one trial); 22/124 (17.7%) in G-CSF group versus 10/70 (14.3%) in placebo group; RR 1.24 (95% 0.62 to 2.47). RetransplantationThere were no differences between 132 participants (two trials); 4/58 (adjusted proportion: 6.9%) in selective bowel decontamination group versus 6/74 (8.1%) in inactive control group; RR 0.85 (95% CI 0.26 to 2.85); 63 participants (one trial); 1/32 (3.1%) in selective bowel decontamination group versus 0/31 (0%) in prebiotics with probiotics group; RR 2.91 (0.12 to 68.81); 64 participants (one trial); 1/32 (3.1%) in selective bowel decontamination group versus 0/32 (0%) in prebiotics group; RR 3.00 (95% CI 0.13 to 71.00); 129 participants (two tria s); 0/64 (0%) in prebiotics with probiotics group versus 1/65 (1.5%) in prebiotics group; RR 0.33 (95% CI 0.01 to 7.9); and 194 participants (one trial); 10/124 (7.1%) in G-CSF group versus 5/70 (7.1%) in placebo group; RR 1.13 (95% CI 0.4 to 3.17).There was no significant difference in the graft rejections, intensive therapy unit stay, or hospital stay between the intervention and control groups in any of the comparisons. Overall, 193/611 participants (31.6%) developed infective complications. The proportion of people who developed infective complications and the number of infective complication episodes were significantly higher in the selective bowel decontamination group than in the prebiotics with probiotics group (1 study; 63 participants; 15/32 (46.9%) in selective bowel decontamination group versus 4/31 (12.9%) in prebiotics with probiotics group; RR 3.63; 95% CI 1.36 to 9.74 and 23/32 participants (0.72 infective complications per participant) in selective bowel decontamination group versus 4/31 participants (0.13 infective complications per participant) in prebiotics with probiotics group; rate ratio 5.58; 95% CI 1.94 to 16.09). There was no significant difference between the proportion of participants who developed infection and the number of infection episodes between the intervention group and control group in any of the other comparisons.No trials reported quality of life and overall serious adverse events.<br /><br /><strong>AUTHORS' CONCLUSIONS: </strong>Currently, there is no clear evidence for any intervention offering significant benefits in the reduction of bacterial infections and wound complications in liver transplantation. Selective bowel decontamination may even increase the rate of infections compared with prebiotics with probiotics. The confidence intervals were wide and further randomised clinical trials of low risk of bias are necessary.",
Arsenic,656880,"Suppression of p53 and p21CIP1/WAF1 reduces arsenite-induced aneuploidy Abstract: Aneuploidy and extensive chromosomal rearrangements are common in human tumors. The role of DNA damage response proteins p53 and p21(CIP1/WAF1) in aneugenesis and clastogenesis was investigated in telomerase immortalized diploid human fibroblasts using siRNA suppression of p53 and p21(CIP1/WAF1). Cells were exposed to the environmental carcinogen sodium arsenite (15 and 20 microM), and the induction of micronuclei (MN) was evaluated in binucleated cells using the cytokinesis-block assay. To determine whether MN resulted from missegregation of chromosomes or from chromosomal fragments, we used a fluorescent in situ hybridization with a centromeric DNA probe. Micronuclei were predominantly of clastogenic origin in control cells regardless of p53 or p21(CIP1/WAF1) expression. MN with centromere signals in cells transfected with NSC siRNA or Mock increased 30% after arsenite exposure, indicating that arsenite induced aneuploidy in the tGM24 cells. Although suppression of p53 increased the fraction of arsenite-treated cells with MN, it caused a decrease in the fraction with centromeric DNA. Suppression of p21(CIP1/WAF1) like p53 suppression decreased the fraction of MN with centromeric DNA. Our results suggest that cells lacking normal p53 function cannot become aneuploid because they die by mitotic arrest-associated apoptosis, whereas cells with normal p53 function that are able to exit from mitotic arrest can become aneuploid. Furthermore, our current results support this role for p21(CIP1/WAF1) since suppression of p21(CIP1/WAF1) caused a decrease in aneuploidy induced by arsenite, suggesting that p21(CIP1/WAF1) plays a role in mitotic exit.",
Arsenic,710912,"An effective dietary survey framework for the assessment of total dietary arsenic intake in Bangladesh: part-A--FFQ design Abstract: The accurate assessment of dietary intake patterns is important for the determination of total dietary arsenic (As) exposure in As-contaminated regions of Bangladesh. Food intake questionnaires are a common means of assessing food intake. A food frequency questionnaire (FFQ) was designed to assess the daily intake of frequently consumed food items and was successfully implemented to assess dietary patterns and intake of the rural populations in 18 villages from three Districts of Bangladesh (Comilla, Manikganj Sadar, and Munshiganj). The FFQ presented in this paper comprises a complete set of tools which allowed not only collection of information on dietary patterns but also information on the spatial characteristics of the landscape, socio-demographic indicators, and geographic locations of the identified environmental media of the contaminants, which resulted in As exposure to humans. The FFQ was designed in three sections: (1) general household information, (2) household water and rice information, and (3) individual dietary intake of other foods. The dietary intake of other food was then further subdivided into five different food subgroups: (i) grain intake, (ii) protein intake, (iii) fruit intake (iv), vegetable intake, and (v) dal (pulse) intake. During the design and development of the FFQ, emphasis was given to the source of food, the frequency (day/week/month) of consumption, and the daily amount of food consumed by each adult male, adult female, and child to accurately determine the dietary pattern and intake of arsenic in the rural population of Bangladesh.",
Arsenic,2278519,"An EXAFS study on the adsorption structure of phenyl-substituted organoarsenic compounds on ferrihydrite Abstract: Adsorption structures of mono- and diphenyl substituted organoarsenic compounds (PAA and DPAA, respectively) on ferrihydrite were analyzed by extended X-ray absorption fine structure (EXAFS), which suggested that PAA and DPAA form inner-sphere complexes with ferrihydrite regardless of their bulky functional groups. In addition, coexistence of two types of inner-sphere complex modes, i.e. bidentate-binuclear and monodentate surface complexes was suggested by EXAFS fitting with two type of the As-Fe shell.",
Arsenic,1019611,"Alteration in bilirubin excretion in individuals chronically exposed to arsenic in Mexico Abstract: We have studied hepatic function in individuals chronically exposed to arsenic (As) via drinking water in Region Lagunera, Mexico. We studied 51 individuals living in three villages exposed to As in water. Nazareno (0.014 mgAs/l), Santa Ana (0.1 mgAs/l) and Benito Juárez (0.3 mgAs/l). We determined the serum activity of aspartate aminotransferase (SAT) and alanine aminotransferase (ALT) as indicators of hepatocellular injury and that of gamma-glutamyl-transpeptidase (GGT) and alkaline phosphatase (ALP) as indicators of cholestasic injury. Serum bilirubin was used as an indicator of organic conjugated anion transport. Total proteins, albumin and globulin fraction in serum were used as indicators of biosynthetic liver capacity. The main findings of this study were the predominantly conjugated hyperbilirubinemia and increased serum ALP activity which were related to the concentration of total arsenic (TAs) in urine, suggesting the presence of cholestasis in As-exposed individuals. No significant changes were observed in the other parameters studied.",
Arsenic,1508550,"Buildings as repositories of hazardous pollutants of anthropogenic origin Abstract: In the present work the pollutant content of diverse building materials was evaluated by the combination of spectrometric and chromatographic techniques. A first non-destructive analysis carried out by ?-XRF and Raman spectroscopy revealed a high impact of pollutants, which reached depths higher than 6mm. The quantitative analyses pointed out that black crust as accumulation nucleus where concentration values up to 3408mg/kg of lead, 752mg/kg of chromium or 220mg/kg of arsenic, high amounts of diverse sulphates and nitrates as well as substantial amounts of polycyclic aromatic hydrocarbons (PAHs) of a clear pyrolytic source were determined. On the other hand, samples without black crust showed also a surprising soluble salt content up to 5%. Polychlorinated biphenyls (PCB) were found to be absent in all material types. The chemometric analysis of the quantitative results revealed that the accumulation capacity and the subsequent pollutant content depends on the type of construction materials, being mortars the most susceptible.",
Arsenic,1018196,"Micronuclei assay in exfoliated buccal cells from individuals exposed to arsenic in Argentina Abstract: Drinking arsenic (As)-laden water for a long time affects a population's health and leads to chronic hydroarsenicism, which is associated with an increased incidence of different types of cancer. To determine the potential genotoxic risk associated with different degrees of environmental exposure to inorganic As by way of drinking water, micronuclei (MN) frequency in exfoliated buccal cells was evaluated in Argentina among rural populations of Santiago del Estero and urban populations of Buenos Aires. The exposed group in Santiago del Estero (La Firmeza and Santos Lugares localities) showed a significant increase in MN frequency in epithelial cells compared with controls (Monte Quemado and Urutau localities) (p = 0.0005). With regard to the Buenos Aires groups, Navarro individuals (the exposed group) exhibited a significant difference compared with controls (Ciudad Autónoma de Buenos Aires) (p = 0.0002). Comparison of MN frequencies between Santiago del Estero and Buenos Aires individuals showed that genotoxic effects of As in drinking water exhibit variation between rural and urban groups, probably due to individual susceptibility being an important incidence factor. The results clearly show that MN assay in buccal mucosa cells is an ideal methodology with which to measure potential genetic risk related to environmental As exposure in humans.",
Arsenic,627691,"Induction of oxidative stress by arsenic in Clarias batrachus: Involvement of peroxisomes Abstract: Indian catfish, Clarias batrachus, were exposed to two nonlethal doses of arsenic for 10 days, which induced tissue lipid peroxidation, increased the ratio of oxidized to reduced glutathione and produced excess H(2)O(2) within 1-2 days of exposure. Furthermore, arsenic treatment increased the activity of antioxidant enzymes such as glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase but decreased glutathione reductase (GR) activity within a day of exposure, indicating the generation of oxidative stress in fish at an early stage. Reversibility of these arsenic-induced responses by pretreatment with N-acetylcysteine indicates that the oxidative stress was due to excess H(2)O(2) production, which was found to be partially contributed by altered H(2)O(2) metabolism in the peroxisomes. It is therefore concluded that peroxisomal H(2)O(2) metabolizing enzymes are potential targets of arsenic toxicity in C. batrachus.",
Arsenic,628384,"Assessment of apoptosis in thymocytes and splenocytes from mice exposed to arsenate in drinking water: Cytotoxic effects of arsenate on the cells in vitro Abstract: This study provides an assessment of the level of apoptosis in thymocytes and splenocytes from mice exposed to arsenate in drinking water. To simulate the naturally occurring exposure conditions of humans, the animals were exposed to arsenate at the concentrations of 0.5, 5, and 50 mgAs/L. TUNEL method for staining of thymocytes and splenocytes isolated from the mice after 8 and 12 weeks revealed increased percentage of apoptotic cells in the exposed groups. Although statistically significant increases were observed only for the highest concentration of arsenate, the increases showed linear trend as a function of arsenate concentration in drinking water. lcubIn vitrorcub experiments performed on isolated cells incubated for 24 hours with arsenate at 6.7-2000 ?M showed very similar concentration-viability relationships for both cell populations (IC50 was 442 ± 15 ?M and 427 ± 18 ?M for thymocytes and splenocytes, respectively). Arsenate induced a concentration-dependent increase in the percentage of the cells undergoing apoptosis. At higher concentrations, apoptosis was the predominant mode of cell death. It can be speculated that proapoptotic effects of arsenate as observed in our lcubin vivorcub study may contribute to some immunotoxic symptoms observed in people chronically exposed to arsenic in drinking water.",
Arsenic,2345771,"Nanoencapsulation of DMSA monoester for better therapeutic efficacy of the chelating agent against arsenic toxicity Abstract: <strong>AIMS: </strong>Exposure to toxic metals remains a widespread occupational and environmental problem in world. Chelation therapy is a mainstream treatment used to treat heavy metal poisoning. This paper describes the synthesis, characterization and therapeutic evaluation of monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA)-encapsulated polymeric nanoparticles as a detoxifying agent for arsenic poisoning. Materials &amp;<br /><br /><strong>METHODS: </strong>Polymeric nanoparticles entrapping the DMSA monoester, which can evade the reticulo-endothelial system and have a long circulation time in the blood, were prepared. Particle characterization was carried out by transmission electron microscopy and dynamic light scattering. An in vivo study was conducted to investigate the therapeutic efficacy of MiADMSA-encapsulated polymeric nanoparticles (nano- MiADMSA; 50 mg/kg orally for 5 days) and comparison drawn with bulk MiADMSA. Swiss albino mice exposed to sodium arsenite for 4 weeks were treated for 5 days to evaluate alterations in blood, brain, kidney and liver oxidative stress variables. The study also evaluated the histopathological changes in tissues and the chelating potential of the nanoformulation.<br /><br /><strong>RESULTS: </strong>Our results show that nano-MiADMSA have a narrow size distribution in the 50-nm range. We observed an enhanced chelating potential of nano-MiADMSA compared with bulk MiADMSA as evident in the reversal of biochemical changes indicative of oxidative stress and efficient removal of arsenic from the blood and tissues. Histopathological changes and urinary 8-OHdG levels also prove better therapeutic efficacy of the novel formulation for arsenic toxicity.<br /><br /><strong>CONCLUSION: </strong>The results from our study show better therapeutic efficacy of nano-MiADMSA in removing arsenic burden from the brain and liver.",
Arsenic,622668,"Increased susceptibility of human small airway epithelial cells to apoptosis after long term arsenate treatment Abstract: Inorganic arsenic (arsenate and arsenite) are well known human carcinogens. Apoptosis is a normal biological process that is involved in regulating cell development and differentiation, and is an important protective response to cell injury. The aim of this study was to determine the long term arsenic effect on human small airway epithelial cells (SAEC) by analyzing two distinct apoptosis-inducing agents, Fas ligand (Fas L), which evokes death receptor-mediated apoptosis, and hydrogen peroxide H2O2, which induces apoptosis mediated by reactive oxygen species (ROS). The SAEC were continuously exposed to 0.5 Ã‚Âµg/mL arsenic for 28 weeks, and apoptosis was examined after 24 h treatment with either Fas L or H2O2. SAEC displayed decreased cell viability and increased apoptosis after treatment with Fas L and H2O2, compared to non-arsenic treated control cells. Furthermore, treatment of these arsenic-exposed SAEC with Fas L or H2O2 induced cleavage of the DNA damage recognition protein, poly (ADP-ribose) polymerase (PARP), and the Ã¢â‚¬ËœeffectorÃ¢â‚¬â„¢ caspase, Caspase-3, both canonical indicators of apoptosis. We observed increased phosphorylation of p38, a member of the MAP kinase family, following treatment with Fas L or H2O2. To confirm the involvement of p38 in the regulation of apoptosis we pretreated cells with the p38 kinase inhibitor, SB 203580 and observed a significant decrease in apoptosis. [Copyright 2009 Elsevier] Copyright of Science of the Total Environment is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1030044,"Arsenic-induced aberrant gene expression in fetal mouse primary liver-cell cultures Abstract: Exposure of maternal mice to inorganic arsenic through the drinking water induces liver tumors and aberrant gene expression in offspring when they reach adulthood. To help define if these are direct fetal effects of arsenic, fetal liver cells were isolated from untreated mice at gestation day 13.5 by mechanical dissection and centrifugation. Two hours after seeding the cells on collagen1-coated plates in William E media containing 10% fetal bovine serum, 1x ITS (insulin, transferrin, and selenium) and antibiotics, inorganic arsenite (0, 0.1, 0.3, and 1.0 microM) was added to the fresh media for 72 h. Cell morphology and viability were not significantly altered by these arsenic concentrations. At the end of arsenic exposure, cells were harvested into Trizol, and total RNA was extracted, purified, and subjected to real-time reverse transcriptase polymerase chain reaction (RT-PCR) analysis. Arsenite exposure produced a concentration-dependent induction of heme oxygenase-1 (up to eight-fold) and metallothionein-1 (up to five-fold), indicative of stress response to adapt to arsenic insult. Expression of genes related to steroid metabolism, such as 17beta-hydroxysteroid dehydrogenase-7 (HSD17beta7) and Cyp2a4, were increased approximately two-fold, together with increases in estrogen receptor-alpha (ER-alpha) and ER-alpha-linked genes, such as anterior gradient-2, keratin 1-19, and trefoil factor-3. Arsenic in vitro induced a three-fold increase in the expression of alpha-fetoprotein (AFP), a biomarker associated with transplacental arsenic-induced mouse liver tumors. Thus, exposure of mouse fetal liver cells to arsenic induces adaptive responses and aberrant gene expression, which could alter genetic programming at a very early life stage, potentially contributing to tumor formation much later in life.",
Arsenic,2279432,"Bioaccessibility, release kinetics, and molecular speciation of arsenic and lead in geo-dusts from the Iron King Mine Federal Superfund site in Humboldt, Arizona Abstract: Mine tailings contain multiple toxic metal(loid)s that pose a threat to human health via inhalation and ingestion. The goals of this research include understanding the speciation and molecular environment of these toxic metal(loid)s (arsenic and lead) as well as the impacts particle size and residence time have on their bioaccessibilty in simulated gastric and lung fluid. Additionally, future work will include smaller size fractions (PM10 and PM2.5) of surface mine tailings, with the goal of increasing our understanding of multi-metal release from contaminated geo-dusts in simulated bio-fluids. This research is important to environmental human health risk assessment as it increases the accuracy of exposure estimations to toxic metal(loid)s.",
Arsenic,627984,"Procedures for calculating cessation lag Abstract: Environmental regulations aimed at reducing cancer risks usually have the effect of reducing exposure to a carcinogen at the time the regulation is implemented. The reduction of cancer risk may occur shortly after the reduced exposure or after a considerable period of time. The time of risk reduction associated with exposure reduction will vary by compound. Some recommended measures of the economic benefits associated with environmental regulations are sensitive to the timing of the risk reductions and cannot be effectively addressed by the conventional dose-response procedures. This paper introduces the concept and methodologies for calculating cessation lag effects, with the specific goal of answering the following questions: (1) How many cancer cases are avoided at age t after cessation (or reduction) of exposure concentration? and (2) How long does the effect of an exposure last after exposure has terminated (or been reduced)? The proposed procedures do not require more information than what is required by the conventional dose-response procedures for which cumulative or an averaged lifetime exposure is used.",
Arsenic,1677595,"Mixed arbuscular mycorrhizal (AM) fungal application to improve growth and arsenic accumulation of Pteris vittata (As hyperaccumulator) grown in As-contaminated soil Abstract: A greenhouse pot experiment was conducted to study the effects of three types of single inoculum [indigenous mycorrhizas (IM) isolated from As mine, Glomus mosseae (GM) and Glomus intraradices (GI)] and two types of mixed inoculum (mixed with IM and either GM or GI) on the growth response of Pteris vittata (hyperaccumulator) and Cynodon dactylon (non-hyperaccumulator) at three levels of As concentrations (0, 100 and 200mgkg(-1)). Both mycorrhizal plants exhibited significantly higher biomass, and N and P accumulation in its tissue than the control. Among the mycorrhizal inoculum, the mixed inoculum IM/GM promoted substantially higher mycorrhizal colonization and arsenate reductase activity in P. vittata than C. dactylon, among all As levels. The portion of Paris arbuscular mycorrhizal structure (observed in colonized roots) together with the highest As translocation factor of 10.2 in P. vittata inoculated with IM/GM was also noted. It was deduced that IM/GM inoculum may be the best choice for field inoculation at any contaminated lands as the inoculum exhibited better adaptation to variable environmental conditions and hence benefited the host plants.",
Arsenic,2347586,"Arsenic biotransformation by Streptomyces sp. isolated from rice rhizosphere Abstract: Isolation and functional analysis of microbes mediating the methylation of arsenic (As) in paddy soils is important for understanding the origin of dimethylarsinic acid (DMA) in rice grains. Here, we isolated from the rice rhizosphere a unique bacterium responsible for As methylation. Strain GSRB54, which was isolated from the roots of rice plants grown in As-contaminated paddy soil under anaerobic conditions, was classified into the genus Streptomyces by 16S rRNA sequencing. Sequence analysis of the arsenite S-adenosylmethionine methyltransferase (arsM) gene revealed that GSRB54 arsM was phylogenetically different from known arsM genes in other bacteria. This strain produced DMA and monomethylarsonic acid when cultured in liquid medium containing arsenite (As[III]). Heterologous expression of GSRB54 arsM in Escherichia coli promoted methylation of As(III) by converting it into DMA and trimethylarsine oxide. These results demonstrate that strain GSRB54 has a strong ability to methylate As. In addition, DMA was detected in the shoots of rice grown in liquid medium inoculated with GSRB54 and containing As(III). Since Streptomyces are generally aerobic bacteria, we speculate that strain GSRB54 inhabits the oxidative zone around roots of paddy rice and is associated with DMA accumulation in rice grains through As methylation in the rice rhizosphere.",
Arsenic,1015753,"Application of HPLC-ICP-MS and HPLC-ESI-MS procedures for arsenic speciation in seaweeds Abstract: Speciation of arsenic in seaweeds was carried out using ion chromatography (IC) for separation and inductively coupled mass spectrometry (ICP-MS) for detection. The arsenic species studied were arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC). Chromatographic separation of all the species was achieved in &lt;9 min in gradient elution mode using (NH(4))(2)CO(3) and methanol at pH 8.5. The outlet of the IC column was directly connected to the nebulizer of ICP-MS for the determination of arsenic. The speciation of arsenic has been carried out in several seaweed samples. A microwave-assisted extraction method was used for the extraction of arsenic species from seaweed samples. With a mixture of mobile phase A and methanol as extractant, the extraction efficiency was &gt;84%, and the recoveries from spiked samples were in the range of 90-106%. The unknown compounds detected in different seaweeds were identified by coupling IC directly with electrospray ionization-mass spectrometry (ESI-MS). Two arsenosugars and tetramethylarsonium ion (TETRA) were identified in different seaweeds. A fat-soluble arsenolipid compound was identified in the extract of certified reference material BCR-279 Ulva lactuca when 1% HNO(3) was used as the extractant. The precision between sample replicates was &gt;9% for all determinations. The limits of detection were in the range of 0.006-0.015 ?g L(-1) for various arsenic species based on peak height.",
Arsenic,710875,"Associations of plasma selenium with arsenic and genomic methylation of leukocyte DNA in Bangladesh Abstract: Global hypomethylation of DNA is thought to constitute an early event in some cancers and occurs in response to arsenic (As) exposure and/or selenium (Se) deficiency in both in vitro and animal models. In addition, antagonism between As and Se, whereby each reduces toxicity of the other, has been well documented in animal models. Se status may therefore modify the health effects of As in As-exposed populations.<br /><br /> The primary objectives of our study were to test the hypothesis that Se deficiency is associated with genomic hypomethylation of lymphocyte DNA and to determine whether Se levels are associated with blood As (bAs) and urinary As (uAs) concentrations in adults exposed to As-contaminated groundwater in Bangladesh. A secondary objective was to explore the relationships between plasma Se and As metabolites.<br /><br /> We assessed plasma Se concentrations, As metabolite profiles in blood and urine, and genomic methylation of leukocyte DNA in a cross-sectional study of 287 adults.<br /><br /> After adjustment for potential confounders, we observed an inverse association between Se (micrograms per liter) and genomic DNA methylation (disintegrations per minute per 1-µg/L increase in Se): ? = 345.6; 95% confidence interval (CI), 59-632. Se concentrations were inversely associated with total As concentrations (micrograms per liter) in blood (? = -0.04; 95% CI, -0.08 to -0.01) and urine (? = -20.1; 95% CI, -29.3 to -10.9). Se levels were negatively associated with the percentage of monomethylarsinic acid (? = -0.59; 95% CI, -1.04 to -0.13) and positively associated with the percentage of dimethylarsinic acid (? = 0.53; 95% CI, 0.04 to 1.01) in blood.<br /><br /> Our results suggest that Se is inversely associated with genomic DNA methylation. The underlying mechanisms and implications of this observation are unclear and warrant further investigation. In addition, Se may influence bAs and uAs concentrations, as well as relative proportions of As metabolites in blood.",
Arsenic,628036,"Arsenite stimulates plasma membrane NADPH oxidase in vascular endothelial cells Abstract: Low-level arsenite treatment of porcine aortic endothelial cells (PAEC) stimulated superoxide accumulation that was attenuated by inhibitors of NAD(P)H oxidase. To demonstrate whether arsenite stimulated NADPH oxidase, intact PAEC were treated with arsenite for up to 2 h and membrane fractions were prepared to measure NADPH oxidase activity. Arsenite (5 microM) stimulated a twofold increase in activity by 1 h, which was inhibited by the oxidase inhibitor diphenyleneiodonium chloride. Direct treatment of isolated membranes with arsenite had no effect. Analysis of NADPH oxidase components revealed that p67(phox) localized exclusively to membranes of both control and treated cells. In contrast, cytosolic Rac1 translocated to the membrane fractions of cells treated with arsenite or angiotensin II but not with tumor necrosis factor. Immunodepletion of p67(phox) blocked oxidase activity stimulated by all three compounds. However, depleting Rac1 inhibited responses only to arsenite and angiotensin II. These data demonstrate that stimulus-specific activation of NADPH oxidase in endothelial cells was the source of reactive oxygen in endothelial cells after noncytotoxic arsenite exposure.",
Arsenic,2337186,"Arsenic and cadmium are inhibitors of cyanobacterial dinitrogenase reductase (nifH1) gene Abstract: The enzyme nitrogenase complex is a key component conferring nitrogen fixation in all known diazotrophs. This study for the first time examines the impact of As, Na, Cd, Cu and butachlor on component II (dinitrogenase reductase, nifH1) of nitrogenase from diazotrophic cyanobacterium Anabaena sp. PCC7120 using in silico and wet lab approaches. The nifH1 of Anabaena is a glycine-rich stable protein having DNA-binding properties and shows close similarity with free living compared with symbiotic diazotrophs. Phylogenetic tree revealed an adverse effect of the selected stresses on close homologs across the diazotroph community. The protein interaction network demonstrated the presence of nirA, glnA, glnB, alr4255 and alr2485 proteins besides nif proteins, suggesting their involvement in nitrogen fixation along with nifH1. Homology modelling and docking under As, Na, Cd, Cu and butachlor revealed an interaction between stressors and nifH1 protein which was further validated by a transcript of the gene through quantitative real-time PCR (qRT-PCR). Presence of binding sites for As, Na, Cd and Cu on oxyR promoter attested their adverse affects on nifH1. Maximum down-regulation of nifH1 in Cd and As followed by salt, copper and butachlor revealed that arsenic and cadmium were most potential inhibitors of nitrogenase of diazotrophic community, which might negatively affect crop yield.",
Arsenic,1016914,"Decrease of fibrinolytic activity in human endothelial cells by arsenite Abstract: Blackfoot disease (BFD) is an endemic peripheral vascular occlusive disease that occurred in the southwest coast of Taiwan. It is believed that arsenic in the drinking water from artesian wells plays an important role in the development of the disease. We have previously shown that BFD patients had significant lower tissue-type plasminogen activator (t-PA) antigen level and higher plasminogen activator inhibitor, Type 1 (PAI-1) antigen level than normal controls. The purpose of this study was to investigate the effects of arsenite on the fibrinolytic and anticoagulant activities of cultured macrovascular and microvascular endothelial cells. Incubation of human microvascular endothelial cells (HMEC-1), but not human umbilical vein endothelial cells (HUVECs), with arsenite caused a decrease of t-PA mRNA level, a rise of both PAI-1 mRNA level and PAI activity. Arsenite could also inhibit the thrombomodulin (TM) mRNA expression and reduce the TM antigen level in HMEC-1. In conclusion, arsenite had a greater effect on HMEC-1 as compared to HUVECs in lowering the fibrinolytic activity and may be responsible for the reduced capacity of fibrinolysis associated with BFD.",
Arsenic,1337292,"Canadian House Dust Study: Population-based concentrations, loads and loading rates of arsenic, cadmium, chromium, copper, nickel, lead, and zinc inside urban homes Abstract: The Canadian House Dust Study was designed to obtain nationally representative urban house dust metal concentrations (?gg(-1)) and metal loadings (?gm(-2)) for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Consistent sampling of active dust of known age and provenance (area sampled) also permitted the calculation of indoor loading rates (mgm(-2)day(-1) for dust and ?gm(-2)day(-1) for metals) for the winter season (from 2007 to 2010) when houses are most tightly sealed. Geomean/median indoor dust loading rates in homes located more than 2km away from industry of any kind (9.6/9.1mgm(-2)day(-1); n=580) were significantly lower (p&lt;.001) than geomean (median) dust loading rates in homes located within 2km of industry (13.5/13.4mgm(-2)day(-1); n=421). Proximity to industry was characterized by higher indoor metal loading rates (p&lt;.003), but no difference in dust metal concentrations (.29?p?.97). Comparisons of non-smokers' and smokers' homes in non-industrial zones showed higher metal loading rates (.005?p?.038) in smokers' homes, but no difference in dust metal concentrations (.15?p?.97). Relationships between house age and dust metal concentrations were significant for Pb, Cd and Zn (p&lt;.001) but not for the other four metals (.14?p?.87). All seven metals, however, displayed a significant increase in metal loading rates with house age (p&lt;.001) due to the influence of higher dust loading rates in older homes (p&lt;.001). Relationships between three measures of metals in house dust - concentration, load, and loading rate - in the context of house age, smoking behavior and urban setting consistently show that concentration data is a useful indicator of the presence of metal sources in the home, whereas dust mass is the overriding influence on metal loadings and loading rates.",
Arsenic,627420,"Transplacental exposure to inorganic arsenic at a hepatocarcinogenic dose induces fetal gene expression changes in mice indicative of aberrant estrogen signaling and disrupted steroid metabolism Abstract: Exposure to inorganic arsenic in utero in C3H mice produces hepatocellular carcinoma in male offspring when they reach adulthood. To help define the molecular events associated with the fetal onset of arsenic hepatocarcinogenesis, pregnant C3H mice were given drinking water containing 0 (control) or 85 ppm arsenic from day 8 to 18 of gestation. At the end of the arsenic exposure period, male fetal livers were removed and RNA isolated for microarray analysis using 22K oligo chips. Arsenic exposure in utero produced significant (p<0.001) alterations in expression of 187 genes, with approximately 25% of aberrantly expressed genes related to either estrogen signaling or steroid metabolism. Realtime",1
Arsenic,1372310,"Health effects of arsenic in drinking water: Research needs Abstract: BIOSIS COPYRIGHT: BIOL ABS. Research needed to resolve the uncertainties of cancer risk from ingestion of arsenic in drinking water is described. The recommendations fall into two categories reflecting the areas of greatest uncertainty regarding the assessment of arsenic risk: research on the mechanism of cancer, and research on the metabolism and detoxification of arsenic. The recommendations are discussed in light of risk assessment and risk management issues, stressing the need for scientists to interpret research findings for decision managers.",
Arsenic,496413,"Arsenic concentration in tobacco leaves: A study on three commercially important tobacco (Nicotiana tabacum L.) types Abstract: In recent years, arsenic (As) has received increased attention as humans may be exposed to it through occupational and environmental exposure. Tobacco (Nicotiana tabacum L.) like other crops can uptake this element from the soil, which may lead to human exposure. Here, we report on a survey on arsenic in cured or processed tobacco leaves obtained from Africa, Asia, Europe, South and North America. A total of 1,431 leaf samples of flue-cured, burley, and Oriental tobaccos were obtained from various sampling locations during 2002 to 2004. Arsenic concentration in the samples averaged 0.4 +/- 0.6 mu g g(-1) as determined by inductively coupled plasma-mass spectrometry. Recorded values from most samples showed that concentrations of arsenic were usually found at the lower end of the distribution. Significant differences were found among tobacco types, sampling locations, and crop years. Arsenic concentrations were rather low in the majority of regions investigated, which is compatible with data from the literature. However, sample size was small and sampling geographically restricted. Our results would need to be validated with a larger dataset.",
Arsenic,626997,"Effects of chronic exposure to sodium arsenite on hypothalamo-pituitary-testicular activities in adult rats: possible an estrogenic mode of action Abstract: Background: Inorganic arsenic is a major water pollutant and a known human carcinogen that has a suppressive influence on spermatogenesis and androgenesis in male reproductive system. However, the actual molecular events resulting in male reproductive dysfunctions from exposure to arsenic remain unclear. In this context, we evaluated the mode of action of chronic oral exposure of sodium arsenite on hypothalamo-pituitary- testicular activities in mature male albino rats. Methods: The effect of chronic oral exposure to sodium arsenite (5 mg/kg body weight/day) via drinking water without or with hCG (5 I.U./kg body weight/day) and oestradiol (25 micrograms oestradiol 3-benzoate suspended in 0.25 ml olive oil/rat/day) co-treatments for 6 days a week for 4 weeks (about the duration of two spermatogenic cycle) was evaluated in adult male rats. Changes in paired testicular weights, quantitative study of different varieties of germ cells at stage VII of spermatogenic cycle, epididymal sperm count, circulatory concentrations of hormones (LH, FSH, testosterone and corticosterone), testicular activities of delta 5, 3beta-hydroxysteroid dehydrogenase (delta 5, 3beta-HSD), 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD), sorbitol dehydrogenase (SDH), acid phosphatase (ACP), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH), as well as the levels of biogenic amines (dopamine, noradrenaline and 5- hydroxytryptamine (5-HT)) in the hypothalamus and pituitary were monitored in this study. Hormones were assayed by radioimmuno- assay or enzyme- linked immunosorbent assay and the enzymes were estimated after spectrophotometry as well as the biogenic amines by HPLC electrochemistry. Results: Sodium arsenite treatment resulted in: decreased paired testicular weights; epididymal sperm count; plasma LH, FSH, testosterone and testicular testosterone concentrations; and increased plasma concentration of corticosterone. Testicular enzymes such as delta 5, 3 beta-HSD, 17 beta-HSD, and sorbitol dehydrogenase (SDH) were significantly decreased, but those of acid phosphatase (ACP), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were significantly increased. A decrease in dopamine or an increase in noradrenaline and 5-HT in hypothalamus and pituitary were also noted after arsenic exposure. Histological evaluation revealed extensive degeneration of different varieties of germ cells at stage VII of spermatogenic cycle in arsenic exposed rats. Administration of human chorionic gonadotrophin (hCG) along with sodium arsenite partially prevented the degeneration of germ cells and enhanced paired testicular weights, epididymal sperm count, plasma and intratesticular testosterone concentrations, activities of delta 5, 3beta-HSD, 17 beta-HSD and sorbitol dehydrogenase along with diminution in the activities of ACP, ALP and LDH. Since many of the observed arsenic effects could be enhanced by oestradiol, it is suggested that arsenic might somehow acts through an estrogenic mode of action. Conclusion: The results indicate that arsenic causes testicular toxicity by germ cell degeneration and inhibits androgen production in adult male rats probably by affecting pituitary gonadotrophins. Estradiol treatment has been associated with similar effects on pituitary testicular axis supporting the hypothesis that arsenite might somehow act through an estrogenic mode of action.",
Arsenic,2279181,"Metastasis to subsegmental and segmental lymph nodes in patients resected for non-small cell lung cancer: prognostic impact Abstract: <strong>BACKGROUND: </strong>We investigated the prognostic significance of segmental and subsegmental (level 13 and 14) lymph nodes metastasis in patients with resected non-small cell lung cancer (NSCLC).<br /><br /><strong>METHODS: </strong>The pattern of lymph nodal metastasis was analyzed in 124 patients with pN1 NSCLC. Long-term outcomes were compared for 390 pN0, 124 pN1, and 82 pN2 consecutive patients submitted to planned pulmonary resection for NSCLC between 2000 and 2006. The pN1 status was stratified into 3 groups according to the highest level of lymph node involvement: level 10 (hilar); level 11+12 (lobar + interlobar); and level 13+14 (segmental + subsegmental).<br /><br /><strong>RESULTS: </strong>The 5-year overall survival (OS) rates for pN0, pN1, and pN2 patients were 93%, 66%, and 25%, respectively. The highest level of lymph node involvement was a significant prognostic indicator; the 5-year OS rate for level 13+14, level 11+12, level 10 pN1, and pN2 was 81%, 58%, 48%, and 25%, respectively. Significant differences were recorded in long-term outcome when pN0 and pN1 level 13+14, pN1 level 13+14, and pN1 level 11+12, pN1 level 11+12 and pN1 level 10 were compared (p < 0.05). The median number of examined level 13+14 lymph nodes was 2 (range 0 to 6) and 57% pN1 patients had metastasis at level 13+14 lymph nodes.<br /><br /><strong>CONCLUSIONS: </strong>The highest level of lymph node metastases may be used to stratify outcome of patients with pN1 disease. Routine examination of level 13+14 lymph nodes is to be recommended to correctly identify patients at risk of relapse and predict long-term prognosis.",
Arsenic,628640,"Lack of poly(ADP-ribose) polymerase-1 gene product enhances cellular sensitivity to arsenite Abstract: Arsenite (As3+) has long been known to induce cancer and other degenerative diseases. Arsenite exerts its toxicity in part by generating reactive oxygen species. Identification of genetic factors that contribute to arsenic mutagenicity and carcinogenicity is critical for the treatment and prevention of arsenic exposure in human population. As poly(ADP-ribose) polymerase (PARP) is critical for genomic DNA stability, role of PARP-1 was evaluated in arsenic-induced cytotoxic and genotoxic effects. Our study revealed that telomere attrition, probably owing to arsenite-induced oxidative stress, was much more pronounced in PARP-1-/- mouse embryonic fibroblasts (MEF; 40%) compared with PARP-1+/+ MEFs (10-20%). Correlation observed between telomere reduction and apoptotic death in PARP-1 null cells strongly indicates that the telomere attrition might be a trigger for enhanced apoptotic death after arsenite treatment. Elevated DNA damage detected by alkaline comet assay points to an impaired repair ability of arsenite-induced DNA lesions in PARP-1-/- MEFs. Consistent with elevated DNA damage, increased micronuclei induction reflecting gross genomic instability was also observed in arsenite-treated PARP-1-/- MEFs. Microarray analysis has revealed that arsenite treatment altered the expression of about 311 genes majority of which have known functions in cellular responses to stress/external stimulus and cell growth and/or maintenance. Our results suggest an important role for PARP-1 gene product in the maintenance of chromosome-genome stability in response to arsenite-induced DNA damage.",
Arsenic,1579266,"Specific stress responses to cadmium, arsenic and mercury appear in the metallophyte Silene vulgaris when grown hydroponically Abstract: ",
Arsenic,1017256,"Curcumin prevents DNA damage and enhances the repair potential in a chronically arsenic-exposed human population in West Bengal, India Abstract: Induction of oxidative stress and inhibition of DNA repair are possible modes of arsenic-induced carcinogenesis. In West Bengal, India, several districts contain high levels of arsenic, which are far above the WHO-recommended standard. Prevention of arsenic-induced oxidative stress and induction of repair enzymes by curcumin, an active ingredient of turmeric, may be an effective strategy to combat the adverse effects of arsenic. This study aimed at observing the role of curcumin in reducing 8-hydroxy-20-deoxyguanosine formation and enhancing DNA repair capacity in the arsenic-exposed population of West Bengal. Chronically arsenic-exposed volunteers (n= 66), who were asymptomatic, were selected for this study. Our results indicated that curcumin suppressed the 8-hydroxy-20-deoxyguanosine level and OGG1 expression, which were increased by arsenic. Curcumin also induced DNA repair enzymes involved in both base excision repair and nonhomologous end-joining pathways. In this study, both the protein expression and genetic profile were observed for poly-ADP-ribose polymerase 1, DNA b polymerase, X ray repair cross complement 1, DNA ligase III, DNA protein kinase catalytic sub-unit, X ray repair cross-complement 4, DNA ligase IV, and topoisomerase II b. The results indicated that arsenic-inhibited DNA repair was induced by curcumin, both at protein and genetic levels. Thus, curcumin intervention may be a useful modality for the prevention of arsenic-induced carcinogenesis.",
Arsenic,1016627,"Determination of total arsenic levels by hydride generation atomic absorption spectrometry in foods from south-east Spain: estimation of daily dietary intake Abstract: The total concentration of arsenic in different foods from south-east Spain was determined by hydride generation atomic absorption spectrometry. Mineralization was carried out with an HNO(3)-HClO(4) mixture in a thermostated sand bath. Arsenic determination was performed by the standard addition method. Analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of the technique. The highest arsenic levels were found in seafood, cereals, meat and meat by-products. In meat and meat by-products, the total arsenic measured in meat was significantly higher than that in sausages (p&lt;0.05). In cereals, arsenic concentrations in corn and white rice samples were significantly higher (p&lt;0.01) than those measured in wheat by-products. Mean arsenic concentrations in cheese were statistically lower than those in other dairy products (p&lt;0.01). New data have been provided on the total arsenic content of a variety of foods in Spain, which is important for making exposure estimates. The estimated daily intake of total arsenic in the Spanish diet was 221 microg As day(-1).",
Arsenic,1022000,"Global gene expression changes in human urothelial cells exposed to low-level monomethylarsonous acid Abstract: Bladder cancer has been associated with chronic arsenic exposure. Monomethylarsonous acid [MMA(III)] is a metabolite of inorganic arsenic and has been shown to transform an immortalized urothelial cell line (UROtsa) at concentrations 20-fold less than arsenite. MMA(III) was used as a model arsenical to examine the mechanisms of arsenical-induced transformation of urothelium. A microarray analysis was performed to assess the transcriptional changes in UROtsa during the critical window of chronic 50nM MMA(III) exposure that leads to transformation at 3 months of exposure. The analysis revealed only minor changes in gene expression at 1 and 2 months of exposure, contrasting with substantial changes observed at 3 months of exposure. The gene expression changes at 3 months were analyzed showing distinct alterations in biological processes and pathways such as a response to oxidative stress, enhanced cell proliferation, anti-apoptosis, MAPK signaling, as well as inflammation. Twelve genes selected as markers of these particular biological processes were used to validate the microarray and these genes showed a time-dependent changes at 1 and 2 months of exposure, with the most substantial changes occurring at 3 months of exposure. These results indicate that there is a strong association between the acquired phenotypic changes that occur with chronic MMA(III) exposure and the observed gene expression patterns that are indicative of a malignant transformation. Although the substantial changes that occur at 3 months of exposure may be a consequence of transformation, there are common occurrences of altered biological processes between the first 2 months of exposure and the third, which may be pivotal in driving transformation.",
Arsenic,710967,"Interaction between chronic arsenic exposure via drinking water and plasma lactate dehydrogenase activity Abstract: Arsenic is a potent environmental pollutant that has caused one of the largest public health poisonings in the history of human civilization, affecting tens of millions of people worldwide especially in Bangladesh. Lactate dehydrogenase (LDH) in blood plays an important role in predicting cell or organ damage and as an important clue to the diagnosis of a variety of cancers. However, effect of chronic arsenic exposure on the LDH level in blood has not yet been documented. Since the chronic arsenic exposure is associated with organ damages and multi-site cancers, this research aimed at assaying the plasma level of LDH activity in the population who were exposed to arsenic chronically in Bangladesh. A total of 185 individuals living in arsenic-exposed areas and 121 individuals living in non-exposed area in Bangladesh were recruited as study subjects. Arsenic content in drinking water, hair and nails were estimated by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) and LDH activity was assayed by a spectrophotometer. Significant increase in LDH activity was observed with increasing concentrations of arsenic in water, hair and nails. Further, the study subjects were split into four groups based on the three ways of each exposure metrics (water, hair and nail arsenic concentrations) where the study subjects in the non-exposed area were used as a reference (lowest exposure) group. LDH activity was found to be increased in the higher exposure groups of water and hair arsenic concentrations. LDH activity was also increased at low to medium exposure groups of nail arsenic concentrations.Thus, the elevated plasma LDH activity might be helpful for the early prognosis of organ or tissue damage in the individuals who were exposed to arsenic chronically.",
Arsenic,1025534,"Critical cysteine residues of Kelch-like ECH-associated protein 1 in arsenic sensing and suppression of nuclear factor erythroid 2-related factor 2 Abstract: Arsenic activates nuclear factor erythroid 2-related factor 2 (Nrf2) to induce phase II and antioxidative genes. Here we analyzed arsenic-Kelch-like ECH-associated protein 1 (Keap1) cysteine thiol interaction in Nrf2 activation. Arsenic-based Nrf2 activators, fluorescent biarsenical labeling reagent (FlAsH) and phenylarsine oxide (PAO), were used to probe binding of arsenic to Keap1. Strong fluorescence was observed on binding of FlAsH to purified Keap1. Pretreatment with arsenic, tert-butylhydroquinone (tBHQ), or 2,3-dimercaptopropanol significantly reduced the fluorescent signal. PAO affinity beads effectively pulled down Keap1 in vitro and from hepa1c1c7 cells. Arsenic, tBHQ, free PAO, or cadmium blocked Keap1 pulldown. Furthermore, arsenic and free PAO significantly reduced the free thiol contents of purified or endogenous Keap1. Thus, arsenic, FlAsH, and PAO, as well as tBHQ and cadmium, bind to Keap1 cysteine thiols in a similar fashion. All the domains of Keap1 bound PAO, and the linker region exhibited the highest binding activity. The function of arsenic-Keap1 interaction was evaluated in a reconstituted system that mimics endogenous Nrf2 regulation. Mutation of Cys273 or Cys288 in the linker region resulted in high level basal expression of Nrf2 protein. Mutation of Cys151 abolished Nrf2 activation by arsenic. Overexpression of C273A, C288A, or C151A altered the basal and arsenic-induced expression of Nrf2 target genes. The study shows an important role of Cys273 and Cys288 in the suppression of Nrf2 by Keap1 and a critical function of Cys151 in arsenic responsiveness. Our findings support a model in which arsenic binds to different sets of Keap1 cysteine residues to regulate divergent functions in Nrf2 signal transduction.",
Arsenic,1252108,"Detailed study report of Samta, one of the arsenic-affected villages of Jessore District, Bangladesh Abstract: In Bangladesh, arsenic in groundwater above 0.05 mg/l, the maximum permissible limit laid down by WHO, was found in 41 out of 64 districts, People suffering from arsenicosis have been identified in 20 districts out of the 21 districts me have surveyed so far, To know the magnitude of the calamity, it was necessary to survey thousands of villages in the 41 districts, To get an idea about the situation, we surveyed in detail one village, 'Samta', in Jessore district, having a population of 4841. All the tubewells in the village mere analysed for arsenic, A few hundred hair, nail and urine samples were analysed as well to know the arsenic burden on the population, Furthermore, 600 people were examined for arsenical dermatosis. We have attempted a statistical interpretation of the data.",
Arsenic,1021755,"Sodium arsenite dependent protein expression analysis on human embryonic carcinoma (NCCIT) cell line Abstract: Due to their pluripotent nature, embryonic carcinoma (EC) cell lines are useful for the study of basic and applied aspects of medical therapeutics, disease management and environmental mutagenesis. We evaluated the teratogenic like effects of inorganic arsenic during the early stages of cellular development in NCCIT cells, a type of human EC cells. Using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and MetaCore pathway analysis software (GeneGo), the proteomic expression profiles of NCCIT cells after either short- or long-term sodium arsenite (NaAsO(2)) treatment and of NCCIT cell-derived embryoid bodies (EBs) after short-term NaAsO(2) treatment were studied to determine the toxic effects on the process of normal growth and differentiation. The protein expression profiles of the NaAsO(2)-treated NCCIT cells and EBs were compared with that of untreated NCCIT cells. Short-term NaAsO(2) treatment resulted in the down-regulation of most proteins, with heat shock 90-kDa protein (HSP90) and valosin-containing protein (VCP) being significantly downregulated. Long-term NaAsO(2) treatment caused marked up-regulation of B23/nucleophosmin, glucose regulated protein 78-kDa (GRP78), unc-51-like kinase 3 (ULK3), toll-like receptor 6 precursor (TLR6) and mitogen-activated protein kinase 7 isoform A (MAP3K7). NaAsO(2) treatment of the NCCIT cell-derived EBs resulted in the down-regulation of several tumor-suppressor proteins. Taken together, these data suggest that a wide spectrum of cellular responses is induced to cope with chronic non-lethal toxic stresses in NCCIT cells.",
Arsenic,710886,"Chronic exposure to arsenic in tap water reduces acetylcholine-induced relaxation in the aorta and increases oxidative stress in female rats Abstract: The aim of this work is to determine whether consuming tap water containing arsenic (20 ?g/L) alters oxidative stress levels in female rats and changes vascular response. Whereas nitric oxide produces complete relaxation, arsenic (7 months of exposure) impairs the acetylcholine-induced endothelial relaxation in the rat aorta compared with control rats. Arsenic exposure results in a marked elevation in reactive oxygen species in blood, and delta-aminolevulinic acid dehydratase activity, which is a sensitive biomarker for arsenic toxicity and oxidative stress, is significantly decreased in erythrocytes from 7-month-old rats. Diastolic blood pressure increases significantly in 7-month-old arsenic-treated versus control rats. The percentage of change in peripheral resistance increases. The results indicate that chronic environmental exposure to low levels of arsenic alters the release of vasoactive substances, causes changes in oxidative stress, and increases blood pressure in female rats.",
Arsenic,1146088,"Moderate Perinatal Arsenic Exposure Elevates Markers Of Serotonergic Neurotransmission In Dorsal Hippocampal Formation Of Adult Mice Abstract: Arsenic is one of the most common contaminants in drinking water. While the carcinogenic potential of heavy arsenic exposure has received much attention, studies now suggest that moderate arsenic exposure poses a threat to human cognitive development. We recently observed deficits in hippocampal-dependent learning in adult mice whose mothers consumed 50 ppb arsenic in drinking water during pregnancy and until offspring weaning. Further, corticotrophin releasing factor (CRF) and hippocampal glucocorticoid receptors are decreased in these arsenic-exposed mice. Given that corticosteroids inhibit serotonin 5HT1A receptor expression, we hypothesized that 5HT1A receptor number and function would be elevated in arsenic- exposed mice. We used in vitro autoradiography and microdensitometry to measure 5HT1A receptor density and 5HT1A agonist-stimulated receptor G-protein coupling in the hippocampus, parietal cortex, entorhinal cortex and inferior colliculus in control and arsenic-exposed mice. Histological sections were incubated either with 2 nM [3H]-DPAT to measure 5HT1A receptor density or with 100 pM [35S]- GTPgammaS in the absence and presence of DPAT to measure 5HT1A receptor-G protein coupling. A statistically significant increase in specific [3H]-DPAT binding was observed in the dorsal hippocampal formation of arsenic-exposed mice compared to controls. DPAT binding was also elevated in parietal and entorhinal cortex, though not statistically significant. In addition, DPAT-stimulated [35S]-GTPgammaS binding was significantly elevated in dorsal hippocampal formation of arsenic-exposed mice at a half maximally effective (EC50) concentration of agonist. These results suggest that perinatal arsenic exposure increases 5HT1A receptor expression and function in several forebrain regions, a consequence consistent with arsenic-induced damage to the CRF regulation of the serotonergic system within the hippocampus.",
Arsenic,2064260,"Assessment and Prognostic Relevance of Right Ventricular Contractile Reserve in Patients with Severe Pulmonary Hypertension Abstract: <strong>BACKGROUND: </strong>This study sought to analyze a new approach to assess exercise-induced systolic pulmonary artery pressure (PASP) increase by means of stress-Doppler echocardiography as a possible measure of right ventricular (RV) contractile reserve in patients with severe pulmonary hypertension (PH) and right heart failure.<br /><br /><strong>METHODS AND RESULTS: </strong>In this prospective study, patients with invasively diagnosed pulmonary arterial hypertension or inoperable chronic thromboembolic PH and impaired right ventricular pump function despite a stable targeted PAH medication underwent a broad panel of non-invasive assessments including stress echocardiography and cardiopulmonary exercise testing. Based on the assumption that exercise-induced PASP is a measure of right ventricular contractile reserve patients were classified into 2 groups according to an exercise-induced PASP increase above or below median. Patients were followed for 3.0±1.8 years. Uni- and multivariate analysis were employed for analysis of factors predicting survival. Of 124 patients, 66 were below the median exercise-induced PASP increase of 30 mmHg (low PASP), and 58 patients were above (high PASP). These groups were not significantly different concerning medication and resting hemodynamics. Low PASP was associated with a significantly lower 6-minute walking distance, peak VO2/kg and 1-, 3-, and 4-year survival rate (92%, 69% and 48% respectively vs. 96%, 92% and 89%). In the multivariate Cox model analysis adjusted for age and sex PASP increase during exercise and peak VO2/kg remained as independent prognostic markers (hazard ratio 2.56 for peak VO2/kg and 2.84 for PASP increase).<br /><br /><strong>CONCLUSIONS: </strong>Exercise-induced PASP-increase is of high clinical and prognostic relevance in PH-patients and may indicate right ventricular contractile reserve. Stress Doppler echocardiography may be a useful tool for prognostic assessment in PH-patients.",
Arsenic,710824,"Arsenic in public water supplies and cardiovascular mortality in Spain Abstract: High-chronic arsenic exposure in drinking water is associated with increased cardiovascular disease risk. At low-chronic levels, as those present in Spain, evidence is scarce. In this ecological study, we evaluated the association of municipal drinking water arsenic concentrations during the period 1998-2002 with cardiovascular mortality in the population of Spain.<br /><br /> Arsenic concentrations in drinking water were available for 1721 municipalities, covering 24.8 million people. Standardized mortality ratios (SMRs) for cardiovascular (361,750 deaths), coronary (113,000 deaths), and cerebrovascular (103,590 deaths) disease were analyzed for the period 1999-2003. Two-level hierarchical Poisson models were used to evaluate the association of municipal drinking water arsenic concentrations with mortality adjusting for social determinants, cardiovascular risk factors, diet, and water characteristics at municipal or provincial level in 651 municipalities (200,376 cardiovascular deaths) with complete covariate information.<br /><br /> Mean municipal drinking water arsenic concentrations ranged from &lt;1 to 118 microg/L. Compared to the overall Spanish population, sex- and age-adjusted mortality rates for cardiovascular (SMR 1.10), coronary (SMR 1.18), and cerebrovascular (SMR 1.04) disease were increased in municipalities with arsenic concentrations in drinking water &gt; 10 microg/L. Compared to municipalities with arsenic concentrations &lt; 1 microg/L, fully adjusted cardiovascular mortality rates were increased by 2.2% (-0.9% to 5.5%) and 2.6% (-2.0% to 7.5%) in municipalities with arsenic concentrations between 1-10 and &gt;10 microg/L, respectively (P-value for trend 0.032). The corresponding figures were 5.2% (0.8% to 9.8%) and 1.5% (-4.5% to 7.9%) for coronary heart disease mortality, and 0.3% (-4.1% to 4.9%) and 1.7% (-4.9% to 8.8%) for cerebrovascular disease mortality.<br /><br /> In this ecological study, elevated low-to-moderate arsenic concentrations in drinking water were associated with increased cardiovascular mortality at the municipal level. Prospective cohort studies with individual measures of arsenic exposure, standardized cardiovascular outcomes, and adequate adjustment for confounders are needed to confirm these ecological findings. Our study, however, reinforces the need to implement arsenic remediation treatments in water supply systems above the World Health Organization safety standard of 10 microg/L.",
Arsenic,2347783,"Combined use of multivariate statistical analysis and hydrochemical analysis for groundwater quality evolution: A case study in north chain plain Abstract: Understanding the controlling factor of groundwater quality can enhance promoting sustainable development of groundwater resources. To this end, multivariate statistical analysis (MA) and hydrochemical analysis were introduced in this work. The results indicate that the canonical discriminant function with 7 parameters was established using the discriminant analysis (DA) method, which can afford 100% correct assignation according to the 3 different clusters (good water (GW), poor water (PW), and very poor water (VPW)) obtained from cluster analysis (CA). According to factor analysis (FA), 8 factors were extracted from 25 hydrochemical elements and account for 80.897% of the total data variance, suggesting that groundwater with higher concentrations of sodium, calcium, magnesium, chloride, and sulfate in southeastern study area are mainly affected by the natural process; the higher level of arsenic and chromium in groundwater extracted from northwestern part of study area are derived by industrial activities; domestic and agriculture sewage have important contribution to copper, iron, iodine, and phosphate in the northern study area. Therefore, this work can help identify the main controlling factor of groundwater quality in North China plain so as to make better and more informed decisions about how to achieve groundwater resources sustainable development.",
Arsenic,1027605,"Perturbation of defense pathways by low-dose arsenic exposure in zebrafish embryos Abstract: <strong>BACKGROUND: </strong>Exposure to arsenic is a critical risk factor in the complex interplay among genetics, the environment, and human disease. Despite the potential for in utero exposure, the mechanism of arsenic action on vertebrate development and disease is unknown.<br /><br /><strong>OBJECTIVES: </strong>The objective of this study was to identify genes and gene networks perturbed by arsenic during development in order to enhance understanding of the molecular mechanisms of arsenic action.<br /><br /><strong>METHODS: </strong>We exposed zebrafish embryos at 0.25-1.25 hr postfertilization to 10 or 100 ppb arsenic for 24 or 48 hr. We then used total RNA to interrogate genome microarrays and to test levels of gene expression changes by quantitative real-time polymerase chain reaction (QPCR). Computational analysis was used to identify gene expression networks perturbed by arsenic during vertebrate development.<br /><br /><strong>RESULTS: </strong>We identified a set of 99 genes that responded to low levels of arsenic. Nineteen of these genes were predicted to function in a common regulatory network that was significantly associated with immune response and cancer (p &lt; 10(-41)). Arsenic-mediated expression changes were validated by QPCR.<br /><br /><strong>CONCLUSIONS: </strong>In this study we demonstrated that arsenic significantly down-regulates expression levels of multiple genes potentially critical for regulating the establishment of an immune response. The data also provide molecular evidence consistent with phenotypic observations reported in other model systems. Additional mechanistic studies will help explain molecular events regulating early stages of the immune system and long-term consequences of arsenic-mediated perturbation of this system during development.",
Arsenic,1579401,Arsenate and arsenite: the toxic effects on photosynthesis and growth of lettuce plants Abstract: ,
Arsenic,1340183,"Intracellular accumulation of bilirubin as a defense mechanism against increased oxidative stress Abstract: Antioxidant, anti-inflammatory and anti-atherogenic effects have been associated with elevations of unconjugated bilirubin (UCB) in serum and with the induction of heme oxygenase-1 (HO-1), the rate-limiting enzyme in UCB synthesis. The aim of this study was to investigate the intracellular metabolism and antioxidant properties of UCB in human hepatoblastoma HepG2 cells and tissues of Wistar rats exposed to oxidative stressors and lipopolysaccharide (LPS), respectively. Intracellular UCB concentrations in HepG2 cells correlated with its levels in culture media (p &lt; 0.001) and diminished lipid peroxidation in a dose-dependent manner (p &lt; 0.001). Moreover, induction of HO-1 with sodium arsenite led to 2.4-fold (p = 0.01) accumulation of intracellular UCB over basal level while sodium azide-derived oxidative stress resulted in a 60% drop (p &lt; 0.001). This decrease was ameliorated by UCB elevation in media or by simultaneous induction of HO-1. In addition, hyperbilirubinemia and liver HO-1 induction in LPS-treated rats resulted in a 2-fold accumulation of tissue UCB (p = 0.01) associated with enhanced protection against lipid peroxidation (p = 0.02). In conclusion, hyperbilirubinemia and HO-1 induction associated with inflammation and oxidative stress increase intracellular concentrations of UCB, thus enhancing the protection of cellular lipids against peroxidation. Therefore, the previously reported protective effects of hyperbilirubinemia and HO-1 induction are at least in part due to intracellular accumulation of UCB.",
Arsenic,2347609,"Flavobacterium arsenatis sp. nov., a novel anti-arsenic bacterium from the high-arsenic sediment Abstract: A novel bacterial strain Z(T) was isolated from the high-arsenic sediment in Jianghan Plain, China. The strain was Gram-staining-negative, rod-shaped, and formed yellow colonies. This bacterium is capable of resisting to arsenate and arsenite with the MICs of 40 mM and 20 mM, respectively. The strain also possesses catalase, and doesn't produce oxidase. The nucleotide sequence of the 16S rRNA gene of the isolate showed the highest similarity (96.9%) to that of the type strain of Flavobacterium soli. According to the 16S rRNA gene sequence analysis and the phenotypic properties of the strain Z(T), it was assigned to the genus Flavobacterium. The major respiratory menaquinone was MK-6 and the predominant fatty acids were iso-C15:0, summed feature 3 (containing C16:1?6c and/or C16:1?7c) and iso-C15:1 G. The major polar lipids were phosphatidylethanolamine (PE), three uncharacterized aminophospholipids (APLs) and four unknown phospholipids (PLs). The G+C content is 32.1 mol%. Based on the phenotypic and genotypic data presented in this article, it can be concluded that this isolate represents a novel species of the genus Flaovacterium, for which the name Flavobacterium arsenatis sp. nov. is proposed. The type strain is Z(T) (=CCTCC AB 2013048(T)=KCTC 32397(T)).",
Arsenic,1028051,"Energy and electrode consumption analysis of electrocoagulation for the removal of arsenic from underground water Abstract: A systematic study of the effect of design and operation conditions of an electrochemical reactor on the treatment time for arsenic (As) electro-removal from underground water (GW) was carried out to analyse the energy and electrode consumption. The effects of four factors--current density, interelectrode distance, electrode area-volume ratio, and liquid motion driving mode--were evaluated. The response variables were the energy and the electrode consumption and the treatment time to reduce the GW residual As concentration to 10 microg L(-1), which is the maximum contaminant level (MCL) established by the World Health Organization (WHO) in drinking water. The results obtained in this study showed that the factor that had the greatest effect on most of the response variables was the liquid motion driving mode. The best residence time was 20s, which favoured low energy consumption (58.78 Wh m(-3)) and low electrode material loss (9.59 g m(-3)).",
Arsenic,1597282,"Trilithium thio-arsenate octa-hydrate Abstract: The title compound, Li3AsS4·8H2O, is built up from infinite cationic [Li3(H2O)8](3+) chains which extend along [001] and are cross-linked by isolated tetra-hedral AsS4 (3-) anions via O-H?S hydrogen bonds. Two Li and two As atoms lie on special positions with site symmetries -1 (1 × Li) and 2 (1 × Li and 2 × As). The [Li3(H2O)8](3+) chain contains four independent Li atoms of which two are in octa-hedral and two in tetra-hedral coordination by water O atoms. An outstanding feature of this chain is a linear group of three edge-sharing LiO6 octa-hedra to both ends of which two LiO4 tetra-hedra are attached by face-sharing. Such groups of composition Li5O16 are linked into branched chains by means of a further LiO4 tetra-hedron sharing vertices with four adjacent LiO6 octa-hedra. The Li-O bonds range from 1.876?(5) to 2.054?(6)?Å for the LiO4 tetra-hedra and from 2.026?(5) to 2.319?(5)?Å for the LiO6 octa-hedra. The two independent AsS4 (3-) anions have As-S bond lengths ranging from 2.1482?(6) to 2.1677?(6)?Å [&lt;As-S&gt; = 2.161?(10)?Å]. The eight independent water mol-ecules of the structure donate 16 relatively straight O-H?S hydrogen bonds to all S atoms of the AsS4 tetra-hedra [&lt;O?S&gt; = 3.295?(92)?Å]. Seven water mol-ecules are in distorted tetra-hedral coordination by two Li and two S; one water mol-ecule has a flat pyramidal coordination by one Li and two S. At variance with related compounds like Schlippe's salt, Na3SbS4·9H2O, there are neither alkali-sulfur bonds nor O-H?O hydrogen bonds in the structure.",
Arsenic,1240203,"Arsenic impairs embryo development via down-regulating Dvr1 expression in zebrafish Abstract: Exposure to environmental inorganic arsenic compounds has serious health effects on humans, including cancer, cardiovascular disease, developmental and reproductive problems. Our previous study showed that arsenic exposure caused various signs of toxicity in early stages of zebrafish development, including cardiac and neural system, such as pericardium edema, circulation failure, heart malformation. However, how arsenic exerts these effects is little known. Here, real-time quantitative RT-PCR and whole-mount in situ hybridization data showed that zebrafish Dvr1, a mammalian homolog of GDF1 related to the formation of left-right axis, was significantly down-regulated in embryos exposed to arsenite. Embryos with Dvr1 knockdown by antisense morpholino displayed abnormal development, including pericardium edema and failed looping, which is similar to the defects phenotype with arsenic treatment. Furthermore, overexpression of GDF1 significantly rescued development anomalies caused by morpholino or arsenite. Taken together, our results indicated for the first time that Dvr1 played an important role in the left-right asymmetry establishment of zebrafish embryo, and Dvr1 was involved in arsenic-mediated embryo toxicity, which gives novel insight into molecular mechanism of arsenic-mediated embryo toxicity.",
Arsenic,734984,"Requirement of Arsenic Biomethylation for Oxidative DNA Damage Abstract: BACKGROUND: Inorganic arsenic is an environmental carcinogen that may act through multiple mechanisms including formation of methylated derivatives in vivo. Sodium arsenite (up to 5.0 microM) renders arsenic methylation-competent TRL1215 rat liver epithelial cells tumorigenic in nude mice at 18 weeks of exposure and arsenic methylation-deficient RWPE-1 human prostate epithelial cells tumorigenic at 30 weeks of exposure. We assessed the role of arsenic biomethylation in oxidative DNA damage (ODD) using a recently developed immuno-spin trapping method. METHODS: Immuno-spin trapping was used to measure ODD after chronic exposure of cultured TRL1215 vs RWPE-1 cells, or of methylation-competent UROtsa/F35 vs methylation-deficient UROtsa human urothelial cells, to sodium arsenite. Secreted matrix metalloproteinase (MMP)-2 and -9 activity, as analyzed by zymography, cellular invasiveness by using a transwell assay, and colony formation by using soft agar assay were compared in cells exposed to arsenite with and without selenite, an arsenic biomethylation inhibitor, to assess the role of ODD in the transition to an in vitro cancer phenotype. RESULTS: Exposure of methylation-competent TRL1215 cells to up to 1.0 microM sodium arsenite was followed by a substantial increase in ODD at 5-18 weeks (eg, at 16 weeks with 1.0 microM arsenite, 1138% of control, 95% confidence interval [CI] = 797% to 1481%), whereas exposure of methylation-deficient RWPE-1 cells to up to 5.0 microM arsenite did not increase ODD for a 30-week period. Inhibition of arsenic biomethylation with sodium selenite abolished arsenic-induced ODD and invasiveness, colony formation, and MMP-2 and -9 hypersecretion in TRL1215 cells. Arsenic induced ODD in methylation-competent UROtsa/F35 cells (eg, at 16 weeks, with 1.0 microM arsenite 225% of control, 95% CI = 188% to 262%) but not in arsenic methylation-deficient UROtsa cells, and ODD levels corresponded to the levels of increased invasiveness, colony formation, and hypersecretion of active MMP-2 and -9 seen after transformation to an in vitro cancer phenotype. CONCLUSION: Arsenic biomethylation appears to be obligatory for arsenic-induced ODD and appears linked in some cells with the accelerated transition to an in vitro cancer phenotype.",
Arsenic,1070488,"The effects of radial oxygen loss on arsenic tolerance and uptake in rice and on its rhizosphere Abstract: Understanding the complex biotic and abiotic interactions invoked by the rice root system in oxygen-depleted soil is an important step in screening genotypes for low toxic metal or metalloid accumulation. A hydroponic and a rhizobox experiment have been conducted to explore the effects of varying root oxygen release on chemical changes, As fractionation in rhizosphere soil and Fe plaque formation, As uptake and tolerance by different rice genotypes. The results showed that rice genotypes with higher rates of radial oxygen loss (ROL) and at the bolting stage, tended to have greater effects on rhizosphere Eh, pH, Fe(3+)/Fe(2+) quotients, As fractionation and mobility and also on Fe plaque formation compared to those with lower ROL and at the tillering stage. Genotypes with higher ROL have a strong ability to reduce As accumulation in shoots and increase As tolerance by reducing As mobilization in the rhizosphere and by limiting As translocation.",
Arsenic,55874,"Biological monitoring of environmental pollution and human exposure to metals in Tarragona, Spain III Blood levels Abstract: Blood samples were obtained from 72 men and 72 women (age > 16 years) living in 3 residential areas in the vicinity of a new hazardous waste incinerator (HWI), now under construction (Tarragona, Spain). The samples were subjected to arsenic (As), beryllium (Be), cadmium (Cd),chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (TI), and vanadium (V) analyses. Beryllium, Cd, Cr, Mn, Ni, Pb, Tl, Sn, and V were measured by ICP-MS. Arsenic and Hg were determined by using hydride generation/ICP-MS. Results were analyzed in terms of age, sex, and specific place of residence. Arsenic, Be, TI, and V levels were under the respective detection limits. The geometric mean concentrations and ranges ( g/dl) of the remaining elements were the following: Cd 0.70 (0.20-3.24), Cr 0.02 (0.01 -0.11), Hg 0.68 (0.37 - 3.54), Mn 1.90 (0.35- 14.90), Ni 1.39 (0.08- 8.81), Pb 3.83 (1.20- 27.91), and Sn 1.14 (0.007-9.30). No differences in relation to sex were observed. In turn, only Cr (men) and Hg (men and women) concentrations were significantly increased with age. However, significant differences depending on the place of residence of the subjects were noted in the blood concentrations of Cd, Hg, Mn, and Pb. The current blood levels of Cd, Mn, and Pb show some remarkable differences compared to those found in previous surveys.",
Arsenic,1797823,"Uptake of arsenic species by turnip (Brassica rapa L.) and lettuce (Lactuca sativa L.) treated with roxarsone and its metabolites in chicken manure Abstract: Roxarsone is an organoarsenic feed additive that can be metabolised to other higher toxic arsenic (As) species in animal manure such as arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, 3-amino-4-hydroxyphenylarsonic acid and other unknown As species. The accumulation, transport and distribution of As species in turnip (Brassica rapa L.) and lettuce (Lactuca sativa L.) amended with roxarsone and its metabolites in chicken manure were investigated. Results showed arsenite was the predominant As form, followed by arsenate in turnip and lettuce plants, and a low content of dimethylarsinic acid was detected only in lettuce roots. Compared with the control plants treated with chicken manure without roxarsone and its metabolites, the treatments containing roxarsone and its metabolites increased arsenite content by 2.0-3.2% in turnip shoots, by 6.6-6.7% in lettuce shoots, by 11-44% in turnip tubers and by 18-20% in lettuce roots at two growth stages. The enhanced proportion of arsenate content in turnip shoots, turnip tubers and lettuce roots was 4.3-14%, 20-35% and 70%, respectively, while dimethylarsinic acid content in lettuce roots increased 2.4 times. Results showed that the occurrence of dimethylarsinic acid in lettuce roots might be converted from the inorganic As species and the uptake of both inorganic and organic As compounds in turnip and lettuce plants would be enhanced by roxarsone and its metabolites in chicken manure. The pathway of roxarsone metabolites introduced into the human body via roxarsone ? animal ? manure ? soil ? crop was indicated.",
Arsenic,2337203,"Applying carbon dioxide, plant growth-promoting rhizobacterium and EDTA can enhance the phytoremediation efficiency of ryegrass in a soil polluted with zinc, arsenic, cadmium and lead Abstract: This study was conducted to investigate the use of elevated carbon dioxide (CO2), plant growth-promoting rhizobacterium Burkholderia sp. D54 (PGPR) and ethylenediaminetetraacetic acid (EDTA) to enhance the phytoextraction efficiency of ryegrass in response to multiple heavy metal (or metalloid)-polluted soil containing zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb). All of the single or combined CO2, PGPR and EDTA treatments promoted ryegrass growth. The stimulation of ryegrass growth by CO2 and PGPR could primarily be attributed to the regulation of photosynthesis rather than decreased levels of Zn, As and Cd in the shoots. Most treatments seemed to reduce the Zn, As and Cd contents in the shoots, which might be associated with enhanced shoot biomass, thus causing a &quot;dilution effect&quot; regarding their levels. The combined treatments seemed to perform better than single treatments in removing Zn, As, Cd and Pb from soil, judging from the larger biomass and relatively higher total amounts (TAs) of Zn, As, Cd and Pb in both the shoots and roots. Therefore, we suggest that the CO2 plus PGPR treatment will be suitable for removing Zn, As, Cd and Pb from heavy metal (or metalloid)-polluted soils using ryegrass as a phytoremediation material.",
Arsenic,2064248,"Biosorption of As (III) by Non-living Biomass of an Arsenic-Hypertolerant Bacillus cereus Strain SZ2 Isolated from a Gold Mining Environment: Equilibrium and Kinetic Study Abstract: The ability of non-living biomass of an arsenic-hypertolerant Bacillus cereus strain SZ2 isolated from a gold mining environment to adsorb As (III) from aqueous solution in batch experiments was investigated as a function of contact time, initial As (III) concentration, pH, temperature and biomass dosage. Langmuir model fitted the equilibrium data better in comparison to Freundlich isotherm. The maximum biosorption capacity of the sorbent, as obtained from the Langmuir isotherm, was 153.41 mg/g. The sorption kinetic of As (III) biosorption followed well the pseudo-second-order rate equation. The Fourier transform infrared spectroscopy analysis indicated the involvement of hydroxyl, amide and amine groups in As (III) biosorption process. Field emission scanning electron microscopy-energy dispersive X-ray analysis of the non-living B. cereus SZ2 biomass demonstrated distinct cell morphological changes with significant amounts of As adsorbed onto the cells compared to non-treated cells. Desorption of 94 % As (III) was achieved at acidic pH 1 showing the capability of non-living biomass B. cereus SZ2 as potential biosorbent in removal of As (III) from arsenic-contaminated mining effluent.",
Arsenic,1597401,"Biosorption of Arsenic by Mosambi (Citrus limetta) Peel: Equilibrium, Kinetics, Thermodynamics and Desorption Study Abstract: ",
Arsenic,1797784,"(Micro)spectroscopic analyses of particle size dependence on arsenic distribution and speciation in mine wastes Abstract: The chemical speciation and distribution of potentially toxic metal(loid)s in mine wastes is critical to assessing the risks posed by these wastes and predicting the potential bioavailability of the metal(loid)s present. Of additional potential importance is the role of particle size in the fate, transport, and toxicity of contaminated mining materials. Spectroscopic analyses of size-separated mine tailings and adjacent background samples from the Randsburg Historic Mining District, California were conducted to quantify the speciation and distribution of arsenic (As) as a function of particle size. Micro-X-ray fluorescence (?XRF) mapping of separate size fractions was used to identify multiple populations of particles with different As:Fe ratios, indicating a variety of distinct arsenic-bearing species. Bulk extended X-ray absorption fine structure (EXAFS) spectroscopy identified phases including arseniosiderite, Ca2Fe3(3+)(AsO4)3O3·3H2O, and As(V) sorbed to iron hydroxides (ferrihydrite, goethite), confirming a strong statistical correlation between arsenic and iron observed in both ?XRF studies and bulk chemical analyses. Differences in As speciation between the mine tailings and background samples also suggest that weathering of crystalline As-bearing phases in tailings leads to sorption of dissolved arsenic to iron hydroxides in nontailings background material.",
Arsenic,1337520,"Cancer and non-cancer health effects from food contaminant exposures for children and adults in California: a risk assessment Abstract: ABSTRACT: BACKGROUND: In the absence of current cumulative dietary exposure assessments, this analysis was conducted to estimate exposure to multiple dietary contaminants for children, who are more vulnerable to toxic exposure than adults. METHODS: We estimated exposure to multiple food contaminants based on dietary data from preschool-age children (2--4 years, n=207), school-age children (5--7 years, n=157), parents of young children (n=446), and older adults (n=149). We compared exposure estimates for eleven toxic compounds (acrylamide, arsenic, lead, mercury, chlorpyrifos, permethrin, endosulfan, dieldrin, chlordane, DDE, and dioxin) based on self-reported food frequency data by age group. To determine if cancer and non-cancer benchmark levels were exceeded, chemical levels in food were derived from publicly available databases including the Total Diet Study. RESULTS: Cancer benchmark levels were exceeded by all children (100%) for arsenic, dieldrin, DDE, and dioxins. Non-cancer benchmarks were exceeded by &gt;95% of preschool-age children for acrylamide and by 10% of preschool-age children for mercury. Preschool-age children had significantly higher estimated intakes of 6 of 11 compounds compared to school-age children (p&lt;0.0001 to p=0.02). Based on self-reported dietary data, the greatest exposure to pesticides from foods included in this analysis were tomatoes, peaches, apples, peppers, grapes, lettuce, broccoli, strawberries, spinach, dairy, pears, green beans, and celery. CONCLUSIONS: Dietary strategies to reduce exposure to toxic compounds for which cancer and non-cancer benchmarks are exceeded by children vary by compound. These strategies include consuming organically produced dairy and selected fruits and vegetables to reduce pesticide intake, consuming less animal foods (meat, dairy, and fish) to reduce intake of persistent organic pollutants and metals, and consuming lower quantities of chips, cereal, crackers, and other processed carbohydrate foods to reduce acrylamide intake.",
Arsenic,1509363,"Understanding the pK(a) of Redox Cysteines: The Key Role of Hydrogen Bonding Abstract: Many cellular functions involve cysteine chemistry via thiol-disulfide exchange pathways. The nucleophilic cysteines of the enzymes involved are activated as thiolate. A thiolate is much more reactive than a neutral thiol. Therefore, determining and understanding the pK(a)s of functional cysteines are important aspects of biochemistry and molecular biology with direct implications for redox signaling. Here, we describe the experimental and theoretical methods to determine cysteine pK(a) values, and we examine the factors that control these pK(a)s. Drawing largely on experience gained with the thioredoxin superfamily, we examine the roles of solvation, charge-charge, helix macrodipole, and hydrogen bonding interactions as pK(a)-modulating factors. The contributions of these factors in influencing cysteine pK(a)s and the associated chemistry, including the relevance for the reaction kinetics and thermodynamics, are discussed. This analysis highlights the critical role of direct hydrogen bonding to the cysteine sulfur as a key factor modulating the equilibrium between thiol S-H and thiolate S(-). This role is easily understood intuitively and provides a framework for biochemical functional insights.",
Arsenic,1381292,TOXIC EFFECTS OF ARSENIC ON SEED GERMINATION AND SEEDLING GROWTH OF HORSEGRAM DOLICHOS BIFLORUS L Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM NOTE DOLICHOS-BIFLORUS CONTAMINANT,
Arsenic,628423,"High expression of bcl-xL in K562 cells and its role in the low sensitivity of K562 to realgar-induced apoptosis Abstract: Arsenic compounds (As(2)O(3 )or()As(4)S(4)) have been used successfully for the treatment of acute promyelocytic leukemia (APL) for quite a long time. It has been noticed that the sensitivity to apoptosis induced by As(2)O(3 )varies among various leukemia cells. It was reported by several groups that As(2)O(3) could induce apoptosis in APL-derived NB4 cells at concentrations of 0.5-1 mumol/l, whereas in other leukemia cells like K562, As(2)O(3) has no effects at the same concentration. K562 cells undergo apoptosis only when the concentration of As(2)O(3 )is greater than 2 mumol/l. Another arsenic compound, realgar (As(4)S(4)), a traditional Chinese mineral medicine, has been used to treat APL effectively and demonstrated to have lower toxicity than As(2)O(3). It would be interesting to know whether NB4 and K562 cells will show different sensitivity to realgar as well and if there is a difference, what is the cellular mechanism of it. In our present study, K562 cells were much less sensitive than NB4 cells to apoptosis induced by realgar. We confirm that the expression of bcl-x(L) is significantly higher in K562 cells than that in NB4 cells and is not downregulated upon realgar treatment. K562 cells become sensitive to realgar at clinically acceptable concentrations when bcl-x(L) expression level is downregulated by transfecting bcl-x(L) antisense RNA vector into the cells. Our results suggest that the increased bcl-x(L) expression in K562 cells contributes to its insensitivity to realgar-induced apoptosis.",
Arsenic,1070451,"Defining reference values of trace elements in the tear film: Diagnostic methods and possible applications Abstract: The study has been performed on tears of apparently healthy subjects who live and work in urban and rural areas, respectively. After the collection the following elements were investigated: chromium (Cr); arsenic (As); copper (Cu); zinc (Zn); selenium (Se); rubidium (Rb); barium (Ba); lead (Pb) and cobalt (Co). Significantly higher values of As were found in subjects living and working in rural areas as compared to those found in urban area residents (0.290 vs. 0.025; p&lt;0.001). Conversely, Ba and Pb were significantly lower in rural area residents (1.10 vs. 2.50, p=0.027 and 1.70 vs. 1.10, p=0.057, respectively). Our data show that trace elements analysis in tears is possible; further studies could define if it could be a reliable biomarker in persons exposed to high concentration of trace elements due to working or environmental reasons.",
Arsenic,1070489,"Direct effects of arsenic trioxide on action potentials in isolated cardiac tissues: Importance of the choice of species, type of cardiac tissue and perfusion time Abstract: INTRODUCTION: The aim of the present study was to evaluate direct/acute effects of arsenic trioxide on action potentials (APs) in isolated cardiac tissues, and to investigate if the choice of species and tissue and the duration of the perfusion play a role in arsenic-induced acute/direct prolongation of AP/QT. METHODS AND RESULTS: Direct electrophysiological effects of arsenic trioxide were measured in cardiac tissues isolated from four different species using micro-electrode recording. Arsenic (after 30 to 95min perfusion at 10?M) significantly prolonged APD(90), increased triangulation of the AP and elicited early afterdepolarizations (EADs) only in isolated guinea-pig and dog Purkinje fibers but not in rabbit and porcine (minipig) Purkinje fibers. Arsenic induced a prolongation of the APD(90) and increases in triangulation and the occurrence of EADs was not observed in papillary muscles of guinea-pigs and rabbits. Arsenic at 4 increasing concentrations from 0.1?M to 10?M at the standard perfusion-time of 15min per concentration, and after a continuous 90-min perfusion at 1?M and 1Hz did not induce these direct effects on APD(90), triangulation and EADs in isolated guinea-pig Purkinje fibers, but it at 1 µM elicited EADs in 2 out of 7 preparations after 90min at 0.2Hz. DISCUSSION: The present study demonstrates that the choice of species and cardiac tissue as well as perfusion-time play important roles in arsenic-induced direct/acute effects on APD(90) and induction of EADs in vitro.",
Arsenic,629405,"Cytosolic [Ca(2+)] modulates basal GLUT1 activity and plays a permissive role in its activation by metabolic stress and insulin in rat epithelial cells Abstract: The aim of this work was to investigate the role of cytosolic free calcium ([Ca(2+)]c) in the stimulation of GLUT1 by metabolic stress and insulin. Chelation of [Ca(2+)]c with bapta, introduced in rat liver epithelial Clone 9 cells in the acetoxymethyl (AM) form, decreased their basal rate of 2-deoxyglucose uptake in a dose-dependent fashion. Maximal inhibition at 75 microM bapta was by 38 +/- 8% (n = 8). The effect was partially reversed by ionomycin. Basal sugar uptake was also decreased by lowering extracellular [Ca(2+)] in ionomycin-permeabilized cells. Increasing [Ca(2+)]c over its resting level of 168 +/- 32 (n = 27) had no affect on sugar uptake. Chelation of [Ca(2+)]c did not change the abundance of surface GLUT1 and had no significant effect on the affinity of GLUT1 for sugars. In addition, calcium chelation abolished the activation of GLUT1 by azide, arsenate, 2,4-dinitrophenol and insulin. However, [Ca(2+)]c did not increase in the presence of azide. We conclude that [Ca(2+)]c, near or below its resting level, modulates GLUT1 activity over a considerable range and plays a permissive role in the activation of the carrier by metabolic stress and insulin.",
Arsenic,1020721,"Method for the determination of five toxicologically relevant arsenic species in human urine by liquid chromatography-hydride generation atomic absorption spectrometry Abstract: An analytical method for the simultaneous quantitation of arseneous acid (As(III)), arsenic acid (As(V)), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and trimethylarsine oxide (TMAO) in human urine by coupling of high-performance liquid chromatography with hydride generation atomic absorption spectrometry (HPLC/HG-AAS) via a flow-injection interface is presented. After arsenic species separation by anion-exchange displacement chromatography the compounds are on-line reduced to their corresponding hydrides and detected by atomic absorption spectrometry. Detection limits range from 1.1 (TMAO) to 2.6 microg/L (As(V)). The method has been applied to determine arsenic species in the urine of a volunteer before and after consumption of seafood as well as to analyse certified reference urine samples for their arsenic species content.",
Arsenic,2337079,"Development of Isotope Dilution LC-MS/MS Method for Accurate Determination of Arsenobetaine in Oyster Certified Reference Material Abstract: An isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) method has been developed and applied to the determination of arsenobetaine (AsB, (CH3)(3)+AsCH2COO-) from oyster candidate certified reference material (CRM). The exact matching isotope dilution approach was adopted for accurate determination of AsB using C-13(2)-labeled AsB as an internal standard. Efficiencies of different AsB extraction methods were evaluated using a codfish reference material and a simple sonication method was selected as the method of choice for the certification of the oyster candidate CRM. The hydrophilic interaction liquid chromatography (HILIC) combined with electrospray ionization tandem mass spectrometry (ESI/MS/MS) in selected reaction monitoring (SRM) mode was optimized for adequate chromatographic retention and robust quantification of AsB from codfish and oyster samples. By analyzing 12 subsamples taken from each 12 bottles systematically selected from the whole oyster CRM batch, the certified value of AsB was determined as 6.60 mg.kg(-1) +/- 0.31 mg.kg(-1) and it showed excellent between-bottle homogeneity of less than 0.42%, which is represented by relative standard deviation of 12 bottles from the CRM batch. The major source of uncertainty was the certified value of the AsB standard solution.",
Arsenic,1378526,"Occupational exposure to inorganic arsenic in wood workers and taxidermists - Air sampling and biological monitoring Abstract: Arsenic exposure in the following occupational categories was evaluated: taxidermists, workers producing garden fences, workers producing weekend cottages, workers producing new houses, workers impregnating wood with chromium, copper, and arsenic (CCA) solutions, and workers impregnating electric pylons with arsenic solution. Airborne arsenic exposure was documented in 70% (19) of 27 individuals working with products containing arsenic. The maximum exposure concentration in this study was 17.3 mug As/m3, found in a single worker who was filling an impregnation container with CCA pasta. Median exposures of workers working indoors producing garden fences and weekend cottages were 3.7 and 0.9 mug As/m3, respectively. The sum of inorganic arsenic and its methylated metabolites in urine samples was recorded in workers handling arsenic-containing products, their colleagues, and controls (references). The maximum urine concentration recorded in this study was 294.5 nmol As/mmo",
Arsenic,2149332,"Arsenic uptake and phytochelatin synthesis by plants from two arsenic-contaminated sites in Poland Abstract: The aim of our study was to assess the strategy developed by terrestrial plants growing in an area contaminated by arsenic to avoid or minimize the toxic effects caused by this element. Eight plant species from two arsenic-contaminated areas were selected for the investigation. Arsenic uptake by different plants was discussed. The speciation analysis of arsenic in plant leaves was performed as well and both inorganic As(III) and As(V) were detected. Moreover, the concentration of phytochelatins in the investigated terrestrial plants was determined. It was noted that the highest concentration of arsenic was found in herb Robert (Gernium robertianum) 21 mg·kg-1 and common nettle (Urtica dioica) 5.3 mg·kg-1 in the cases of Z?oty Stok and ?omianki, respectively. Phytochelatins were present in all investigated plant species: PC3 was present in the highest concentration in plants from Z?oty Stok (compared to other phytochelatins) while none of the phytochelatins dominated in plants from ?omianki. A correlation between concentrations of phytochelatin and arsenic was found in one of the nettle samples from ?omianki.",
Arsenic,1371595,"Non-Hodgkin's lymphoma among phenoxy herbicide-exposed farm workers in western Washington state Abstract: A case/control study of the incidence of nonHodgkin's lymphoma (NHL) among farms workers exposed to phenoxy acid herbicides in western Washington State was conducted. The study was part of a larger study of the incidence of NHL and soft tissue sarcomas in male agricultural workers exposed to phenoxy acid herbicides in a 13 county area in western Washington State. The cases consisted of 181 males with NHL or soft tissue sarcoma diagnosed between 1981 and 1984 who had ever been employed as farmers. They were matched by age and vital status to 196 farmers not having NHL or soft tissue sarcoma. Odds ratios (ORs) for developing NHL as a function of exposure to phenoxy acid herbicides, duration of employment as farmers, and exposure to other pesticides and chemicals commonly used in agriculture such as chlordane (57749), DDT (50293), organic solvents, lead-arsenate (7784409), other arsenicals, and welding or metal fumes were computed. The OR for developing NHL was slightly, but significantly increased by being employed as a farmer. The risk was significantly increased by working 10 to 19 years as a farmer. The risk was insignificantly increased for working less than 10 years and was decreased for working 20 or more years as a farmer. The risk of developing NHL was not significantly related to exposure to any specific phenoxy acid herbicide or to phenoxy acid herbicides in general. The NHL risk was significantly elevated for exposure to organic solvents and lead-arsenate and nonsignificantly elevated for exposure to the other agricultural chemicals. The authors conclude that farming in western Washington State is associated with a slight, significantly increased risk of NHL. Phenoxy acid herbicides are not associated independently with an increased NHL risk; however, they may increase the risk associated with other pesticides and chemicals used in agriculture.",
Arsenic,1030463,"Blood, sweat, and tears: embedding biological samples in social science research on children Abstract: In the first decade of the 21st Century, calls for interdisciplinary research are commonplace. Yet, relatively few papers discuss how to complete such research successfully. In this paper, I describe the details of data collection focused on five, six and seven-year old children. The project examined the effect of environmental contaminants on children's educational outcomes. It included a primary caregiver interview, a skill test with the child, and a venous blood draw from the child to test for lead, mercury, cadmium, arsenic, nicotine, and cotinine. This paper describes key issues and the solutions I adopted. Challenges discussed here include navigating the Institutional Review Board Process, analyzing the blood, obtaining the supplies needed to draw blood, banking blood for future research, hiring a phlebotomist, and recruiting subjects. While not all details will apply directly to other research projects, this paper provides some perspective on the current realities facing social scientists who decide to collect biological samples.",
Arsenic,1015947,"Arsenite interacts selectively with zinc finger proteins containing C3H1 or C4 motifs Abstract: Arsenic inhibits DNA repair and enhances the genotoxicity of DNA-damaging agents such as benzo[a]pyrene and ultraviolet radiation. Arsenic interaction with DNA repair proteins containing functional zinc finger motifs is one proposed mechanism to account for these observations. Here, we report that arsenite binds to both CCHC DNA-binding zinc fingers of the DNA repair protein PARP-1 (poly(ADP-ribose) polymerase-1). Furthermore, trivalent arsenite coordinated with all three cysteine residues as demonstrated by MS/MS. MALDI-TOF-MS analysis of peptides harboring site-directed substitutions of cysteine with histidine residues within the PARP-1 zinc finger revealed that arsenite bound to peptides containing three or four cysteine residues, but not to peptides with two cysteines, demonstrating arsenite binding selectivity. This finding was not unique to PARP-1; arsenite did not bind to a peptide representing the CCHH zinc finger of the DNA repair protein aprataxin, but did bind to an aprataxin peptide mutated to a CCHC zinc finger. To investigate the impact of arsenite on PARP-1 zinc finger function, we measured the zinc content and DNA-binding capacity of PARP-1 immunoprecipitated from arsenite-exposed cells. PARP-1 zinc content and DNA binding were decreased by 76 and 80%, respectively, compared with protein isolated from untreated cells. We observed comparable decreases in zinc content for XPA (xeroderma pigmentosum group A) protein (CCCC zinc finger), but not SP-1 (specificity protein-1) or aprataxin (CCHH zinc finger). These findings demonstrate that PARP-1 is a direct molecular target of arsenite and that arsenite interacts selectively with zinc finger motifs containing three or more cysteine residues.",
Arsenic,1070350,"Prospective investigation of major dietary patterns and risk of cardiovascular mortality in Bangladesh Abstract: BACKGROUND: Dietary pattern analysis is emerging as a practical, effective tool for relating comprehensive dietary intake to risk of cardiovascular disease mortality. However, no studies have applied this technique to a population outside of the developed world. METHODS: We conducted prospective cohort analyses in 11,116 participants enrolled in the Health Effects of Arsenic Study in Araihazar, Bangladesh, measuring deaths attributable to disease of circulatory system, heart disease, and cerebrovascular disease. Participants were enrolled in 2000 and followed up for an average of 6.6years. Dietary information was obtained through a previously validated food-frequency questionnaire at baseline. RESULTS: Principal component analysis based on our comprehensive, 39 item FFQ yielded 3 dietary patterns: (i) a 'balanced' pattern, comprised of steamed rice, red meat, fish, fruit and vegetables; (ii) an 'animal protein' diet, which was more heavily weighted towards eggs, milk, red meat, poultry, bread, and vegetables; and (iii) a 'gourd and root vegetable' diet that heavily relied on a variety of gourds, radishes, pumpkin, sweet potato, and spinach. We observed a positive association between increasing adherence to the animal protein diet and risk of death from both disease of the circulatory system and heart disease; the hazard ratios were 1.13 (95% CI, 1.00-1.28, p=0.05) and 1.17 (95% CI, 0.99-1.38, p=0.07), respectively, in relation to one standard deviation increase in the factor scores for the animal protein diet pattern, after controlling for age, sex, body mass index, smoking status, and energy intake. The positive association was more significant among ever smokers; the hazard ratios (95% CI) for deaths from disease of the circulatory system and heart disease were 1.17 (1.02-1.34) and 1.20 (1.00-1.45), respectively, in relation to one standard deviation increase in the factor scores for the animal protein diet pattern. CONCLUSIONS: An animal protein-rich diet in rural Bangladesh may increase risk of heart disease mortality, especially among smokers. This emphasizes the need to further explore and address the impact of dietary patterns on cardiovascular disease in populations undergoing epidemiologic transition.",
Arsenic,1018211,"Atorvastatin acts synergistically with N-acetyl cysteine to provide therapeutic advantage against Fas-activated erythrocyte apoptosis during chronic arsenic exposure in rats Abstract: Arsenic is an environmental toxicant that reduces the lifespan of circulating erythrocytes during chronic exposure. Our previous studies had indicated involvement of hypercholesterolemia and reactive oxygen species (ROS) in arsenic-induced apoptotic death of erythrocytes. In this study, we have shown an effective recovery from arsenic-induced death signaling in erythrocytes in response to treatment with atorvastatin (ATV) and N-acetyl cysteine (NAC) in rats. Our results emphasized on the importance of cholesterol in the promotion of ROS-mediated Fas signaling in red cells. Arsenic-induced activation of caspase 3 was associated with phosphatidylserine exposure on the cell surface and microvesiculation of erythrocyte membrane. Administration of NAC in combination with ATV, proved to be more effective than either of the drugs alone towards the rectification of arsenic-mediated disorganization of membrane structural integrity, and this could be linked with decreased ROS accumulation through reduced glutathione (GSH) repletion along with cholesterol depletion. Moreover, activation of caspase 3 was capable of promoting aggregation of band 3 with subsequent binding of autologous IgG and opsonization by C3b that led to phagocytosis of the exposed cells by the macrophages. NAC-ATV treatment successfully amended these events and restored lifespan of erythrocytes from the exposed animals almost to the control level. This work helped us to identify intracellular membrane cholesterol enrichment and GSH depletion as the key regulatory points in arsenic-mediated erythrocyte destruction and suggested a therapeutic strategy against Fas-activated cell death related to enhanced cholesterol and accumulation of ROS.",
Arsenic,2298741,"Cisplatin plus sodium arsenite and hyperthermia induces pseudo-G1 associated apoptotic cell death in ovarian cancer cells Abstract: Cisplatin is effective against solid tumors including ovarian cancer. However, inherent or acquired cisplatin resistance limits clinical success. We recently demonstrated that a combination of sodium arsenite (NaAsO2) and hyperthermia sensitizes p53-expressing ovarian cancer cells to cisplatin by modulating DNA repair pathway and enhancing platinum accumulation. However, it is not understood how this combination therapy modulates cell cycle following platinum-DNA damage. The goal of the present study was to determine if NaAsO2 and hyperthermia alter cisplatin-induced G2 arrest and cause mitotic arrest and mitotic catastrophe. Human epithelial ovarian cancer cells (A2780 and A2780/CP70) were treated with cisplatin ± 20 ?M NaAsO2 at 37 or 39°C for 1 h. Cisplatin ± NaAsO2 at 37 or 39°C caused cells to accumulate in G2/M compartment at 36 h after treatment. Western blot analysis of cyclin A and cyclin B suggested that combined NaAsO2, hyperthermia, and cisplatin induced mitotic arrest. However, we observed &lt; 3% mitotic index and phosphorylation of histone H3 on serine 10 was undetectable. These results did not confirm mitotic arrest. BUBR1 (BUB1B) also was not phosphorylated, suggesting disrupted mitotic checkpoint. Postmitotic cells accumulated in pseudo-G1 as demonstrated by cyclin E stabilization, CDKN1A induction, and hypophosphorylation of retinoblastoma protein. These cells also were positive for Annexin V binding indicating they were apoptotic. In summary, cisplatin plus NaAsO2 and hyperthermia induced pseudo-G1 associated apoptosis in ovarian cancer cells.",
Arsenic,1034495,"Acetylcholinesterase: inhibition by tetranitromethane and arsenite. Binding of arsenite by tyrosine residues Abstract: Tetranitromethane inhibits acetylcholinesterase with respect to the hydrolysis of both acetylthiocholine and indophenyl acetate. The loss of activity with indophenyl acetate, a poor substrate, is preceded by an increase in enzyme activity. Only 12 of the 21 tyrosine residues/monomer of enzyme are susceptible to nitration. Loss of activity with respect to indophenyl acetate occurs well after no further nitration of tyrosines occurs and must be due to the modification of other residues. Incubation of the enzyme with arsenite before nitration results in the nitration of only 10 tyrosines. This experiment reveals that the structural basis for the binding of arsenite is the formation of a diester with two tyrosine residues.",
Arsenic,1021346,"Chronic arsenic poisoning in the rat: treatment with combined administration of succimers and an antioxidant Abstract: The influence of the coadministration of vitamin C or vitamin E on the efficacy of two thiol chelators, meso-2,3-dimercaptosuccinic acid (DMSA) or monoisoamyl DMSA, in counteracting chronic arsenic toxicity was investigated in rats. Vitamin C and vitamin E were only mildly effective when given alone or in combination with the above chelators in mobilizing arsenic from the target tissues. However, combined administration of vitamin C plus DMSA and vitamin E plus MiADMSA led to a more pronounced depletion of brain arsenic. The supplementation of vitamins was significantly effective in restoring inhibition of blood delta-aminolevulinic acid dehydratase (ALAD) oxidative stress in liver, kidneys, and brain as reflected by reduced levels of thiobarbituric acid reactive substance and oxidized and reduced glutathione levels. The results thus lead us to suggest that coadministration of vitamin E or vitamin C may be useful in the restoration of altered biochemical variables (particularly the effects on heme biosynthesis and oxidative injury) although it has only a limited role in depleting arsenic burden.",
Arsenic,1579393,Biogas slurry application elevated arsenic accumulation in rice plant through increased arsenic release and methylation in paddy soil Abstract: ,
Arsenic,1381379,Coordinated surgical and drug treatment of cancer Abstract: Normal cells can proliferate to heal wounds while cancer cells die from chemotherapy with selected sulfhydryl (SH) inhibitors. Choice of the drugs is directed by sensitivity tests run immediately after surgery on each patient's own cancer. The SH-bearing nonhistone chromosomal proteins were predicted to play a major role in regulating genes. Much recent work now suggests that these proteins may play a key role in controlling gene expression.,
Arsenic,1020010,"Effects of ascorbic acid and alpha-tocopherol on arsenic-induced oxidative stress Abstract: Arsenic is an ubiquitous element in the environment causing oxidative burst in the exposed individuals leading to tissue damage. Antioxidants have long been known to reduce the free radical-mediated oxidative stress. Therefore, the present study was designed to determine whether supplementation of alpha-tocopherol (400 mg/kg body weight) and ascorbic acid (200 mg/kg body weight) to arsenic-intoxicated rats (100 ppm in drinking water) for 30 days affords protection against the oxidative stress caused by the metalloid. The arsenic-treated rats showed elevated levels of lipid peroxide, decreased levels of non-enzymatic antioxidants and activities of enzymatic antioxidants. Administration of alpha-tocopherol and ascorbic acid to arsenic-exposed rats showed a decrease in the level of lipid peroxidation (LPO) and enhanced levels of total sulfhydryls, reduced glutathione, ascorbic acid and alpha-tocopherol and so do the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase to near normal. These findings suggest that alpha-tocopherol and ascorbic acid prevent LPO and protect the antioxidant system in arsenic-intoxicated rats.",
Arsenic,79804,"Implications of arsenic genotoxicity for dose response of carcinogenic effects Abstract: Epidemiological data relating arsenic ingestion and skin and internal cancers strongly suggest a sublinear or threshold relationship. Physiological saturation of methylation-based arsenic detoxification has been proposed as one explanation for a sublinear response. We have evaluated the molecular bases for sublinearity in light of new data and hypotheses regarding arsenic genotoxicity and chemical carcinogenesis. A review of the dose–response relationships observed in arsenic genotoxicity assays is presented. With the exception of sister chromatid exchanges, sublinear dose–response relationships for arsenic-induced chromosomal aberrations were observed repeatedly in different mammalian and human cell systems. Arsenic also enhanced the clastogenicity and mutagenicity of other DNA damaging agents with a sublinear dose response. Consistent with the dose response of arsenic-induced genetic alterations, arsenic also inhibited DNA ligases I and II, enzymes which play a role in DNA repair, with a sublinear dose response. In some cases, protective effects of relatively low exposures to arsenic have been observed, again consistent with sublinearity. We discuss recent theories on the mechanism of arsenic carcinogenicity and the potential implications for dose–response modeling and risk assessment. Overall, based on available arsenic genotoxicity data, we conclude that it is likely that arsenic indirectly induces genetic damage with a sublinear dose response in humans, thus providing a biological basis for a sublinear dose–response relationship for human cancer. Furthermore, these results suggest that linear dose–response modeling from populations experiencing high arsenic exposures is likely to overpredict cancer risks at relatively low arsenic levels.",1
Arsenic,1337176,"Arsenic-induced gene expression changes in the neural tube of folate transport defective mouse embryos: Microarray analysis Abstract: Inorganic arsenic occurs naturally in the environment and asan industrial contaminant. Epidemiological studies conducted inheavily polluted areas provide evidence that arsenic exposurecauses adverse health effects. Arsenic is a potent humancarcinogen and a suspected teratogen, although data fromepidemiological studies remains inconclusive. Experiments inlaboratory animals have consistently shown arsenic to beteratogenic, primarily inducing exencephaly. We have shownthat a low folate diet and genetic inactivation of the folatebinding protein 2 (Folbp2) gene both separately, andsynergistically, exacerbate arsenic’s induction of NTDs. In orderto better understand this phenomenon, we performed microarrayanalysis of gene expression in the neural tube of Folbp2-/-embryos exposed to arsenic in utero. Pregnant Folbp2-/-damswere treated with 40 mg/kg sodium arsenate on E 7:12 and E8:12. Embryos from treated and control dams were collected at E8:15, E 9:00 and E 9:12. Anterior neural tubes were dissectedfrom the embryos and total RNA was extracted. After in vitrotranscription and ampli?cation, antisense RNA was biotin-streptavidin labeled and hybridized to the CodeLink UniSet 10KBioarray. No less than 6 embryonic neural tubes (3 controls and3 arsenic treated) were used to evaluate the gene expression ateach of the three selected time-points. Microarray slides werescanned, features extracted and expression values for ~10500 genes were generated. After extensive statistical analysis, weidenti?ed 233 differentially expressed genes: 112 downregulatedgenes, and 121 upregulated genes. Ontological enrichmentanalysis of all differentially expressed genes identi?ed numerousontological groups displaying signi?cant enrichment (P<0.005).These genes were classi?ed into three groups: the I-kappaBkinase/NF-kappaB cascade, oxidative phosphorylation, andeukaryotic translocation elongation factor 1 complex.Speci?cally, the down regulation of oxidative phosphorylationgenes may lead to decreased ATP synthesis and reactive oxygenspecies (ROS) production. As these ROS overwhelm theantioxidant capacity of the cell, oxidative stress ensues,presumably triggering the observed up regulation of genes fromthe I-kappaB kinase/NF-kappaB cascade.",
Arsenic,1936072,"Natural attenuation process via microbial oxidation of arsenic in a high Andean watershed Abstract: Rivers in northern Chile have arsenic (As) concentrations at levels that are toxic for humans and other organisms. Microorganism-mediated redox reactions have a crucial role in the As cycle; the microbial oxidation of As (As(III) to As(V)) is a critical transformation because it favors the immobilization of As in the solid phase. We studied the role of microbial As oxidation for controlling the mobility of As in the extreme environment found in the Chilean Altiplano (i.e., &gt;4000meters above sea level (masl) and &lt;310mm annual rainfall), which are conditions that have rarely been studied. Our model system was the upper Azufre River sub-basin, where the natural attenuation of As from hydrothermal discharge (pH4-6) was observed. As(III) was actively oxidized by a microbial consortium, leading to a significant decrease in the dissolved As concentrations and a corresponding increase in the sediment's As concentration downstream of the hydrothermal source. In-situ oxidation experiments demonstrated that the As oxidation required biological activity, and microbiological molecular analysis confirmed the presence of As(III)-oxidizing groups (aroA-like genes) in the system. In addition, the pH measurements and solid phase analysis strongly suggested that the As removal mechanism involved adsorption or coprecipitation with Fe-oxyhydroxides. Taken together, these results indicate that the microorganism-mediated As oxidation contributed to the attenuation of As concentrations and the stabilization of As in the solid phase, therefore controlling the amount of As transported downstream. This study is the first to demonstrate the microbial oxidation of As in Altiplano basins and its relevance in the immobilization of As.",
Arsenic,484470,"Acetylated H4K16 by MYST1 protects UROtsa cells from arsenic toxicity and is decreased following chronic arsenic exposure Abstract: Arsenic, a human carcinogen that is associated with an increased risk of bladder cancer, is commonly found in drinking water. An important mechanism by which arsenic is thought to be carcinogenic is through the induction of epigenetic changes that lead to aberrant gene expression. Previously, we reported that the SAS2 gene is required for optimal growth of yeast in the presence of arsenite (As-III). Yeast Sas2p is orthologous to human MYST1, a histone 4 lysine 16 (H4K16) acetyltransferase. Here, we show that H4K16 acetylation is necessary for the resistance of yeast to As-III through the modulation of chromatin state. We further explored the role of MYST1 and H4K16 acetylation in arsenic toxicity and carcinogenesis in human bladder epithelial cells. The expression of MYST1 was knocked down in UROtsa cells, a model of bladder epithelium that has been used to study arsenic-induced carcinogenesis. Silencing of MYST1 reduced acetylation of H4K16 and induced sensitivity to As-III and to its more toxic metabolite monomethylarsonous acid (MMA(III)) at doses relevant to high environmental human exposures. In addition, both As-III and MMA(III) treatments decreased global H4K16 acetylation levels in a close- and time-dependent manner. This indicates that acetylated H4K16 is required for resistance to arsenic and that a reduction in its levels as a consequence of arsenic exposure may contribute to toxicity in UROtsa cells. Based on these findings, we propose a novel role for the MYST1 gene in human sensitivity to arsenic. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,1327539,"Sister Chromatid Exchanges in Sheep Peripheral Lymphocytes after in vitro Exposure to Metal-Containing Emission Abstract: BIOSIS COPYRIGHT: BIOL ABS. Industrial pollutants, originated from aluminum processing factory, were tested for induction of sister chromatid exchanges (SCE). Experiments were carried out using sheep peripheral lymphocytes under in vitro assays. The emission tested contained Al, Cd, As, Mn, Pb, Cu, Zn, Fe, Na, Ca, and Mg; the majority of them in the form of sulphides, sulphates, oxides or fluorides. The emission was dissolved and neutralized according to a standard method. The mean of SCE was determined for three concentrations the emitted material (30, 60 and 90 mug /ml) with presence and absence of the metabolic activation (S9 mix). The lowest concentration used corresponded to daily oral intake by sheep grazing on contaminated area. Results from both assays were similar; the significant increase in SCE was observed at the concentration of 60 mug/ml (p 0.01). More conspicuous results were observed without of S 9. No significant decrease in the induction of proliferation index (PI) was found",
Arsenic,2278596,"Bioaccumulation and Translocation of Arsenic in the Ecosystem of the Guandu Wetland, Taiwan Abstract: High arsenic (As) levels occur naturally in geothermal areas, potentially polluting downstream wetland ecosystems. The study was to determine the distribution of As among aqueous, solid, and plant phases in the Guandu Wetland of Taiwan. Chemical compounds (As, Fe, Mn, TOC, SO4 (2-), and FeS2) and isotopic compositions (delta S-34) in water and soil samples were analyzed to characterize the As distribution. The sequential extraction of As and total As in plant samples wasanalyzed to estimate the bioconcentration factor (BCF) and translocation factor (TF; defined as the ratio of metal concentration in the shoots to those in the roots) of As in Kandelia obovata in aqueous and solid phases. The As concentrations in plants (23.69 mg/kg) were higher than in the surrounding water (0.0018 mg/L) and soils (17.24 mg/kg). Kandelia obovata have high As bioavailability and low TF, causing easy adaptation to grow in As-contaminated wetland ecosystems. BCFplants/water (13657.92) was higher than BCFplants/soil (1.38). The uptake and bioaccumulation of As in Kandelia obovata are significant; therefore, Kandelia obovata is an As accumulator. The uptake As by the Kandelia obovata plant might depend on the oxidation of As-contained FeS2 in the aerial roots and/or adsorption of As on root surface.",
Arsenic,1027531,"Respiratory effects in people exposed to arsenic via the drinking water and tobacco smoking in southern part of Pakistan Abstract: In this study, a survey has been conducted during 2005-2007 on surface and groundwater arsenic (As) contamination and its impact on the health of local population, of villages located on the banks of Manchar lake, southern part of Sindh, Pakistan. We have also assessed the relationship between arsenic exposure through respiratory disorders in male subjects with drinking water and smoking cigarettes made from tobacco grown in agricultural land irrigated with As contaminated lake water. The biological samples (blood and scalp hair) were collected from As exposed subjects (100% smokers) and age matched healthy male subjects (40.2% smoker and 59.8% non smokers) belong to unexposed areas for comparison purposes. The As concentration in drinking water (surface and underground water), agricultural soil, cigarette tobacco and biological samples were determined by electrothermal atomic absorption spectrometry. The range of As concentrations in lake water was 35.2-158 microg/L (average 97.5 microg/L), which is 3-15 folds higher than permissible limit of World Health Organization (WHO, 2004). While the As level in local cigarette tobacco was found to be 3-6 folds higher than branded cigarettes (0.37-0.79 microg/g). Arsenic exposed subjects (with and without RD) had significantly elevated levels of As in their biological samples as compared to referent male subject of unexposed area. These respiratory effects were more pronounced in individuals who had also As induced skin lesions. The linear regressions showed good correlations between As concentrations in water versus hair and blood samples of exposed subjects with and without respiratory problems.",
Arsenic,2343563,"Effects of arsenate on tobacco hairy root and seedling growth, and its removal Abstract: Arsenic (As) is a highly toxic environmental contaminant to which most living organisms are exposed. Plants have evolved several mechanisms to cope with this toxic metalloid; however, these mechanisms are only partially understood. The response of plants to As phytotoxicity is highly complex, with considerable variation among species. In this study, arsenate (As+5) effects on germination and early root development of tobacco (Nicotiana tabacum) seedlings were investigated. Also, As+5 tolerance and removal efficiency of tobacco hairy roots (HRs) and seedlings were assessed and compared. Total seed germination capacity was not affected by 10 to 200 mu M As+5, while primary root length and root branching were reduced by As+5 concentrations that were at or above 100 mu M. Both systems were able to tolerate As+5 concentrations of 10 mu M since no growth inhibition was detected. For higher As+5 concentrations, phytotoxicity increased, but it was mitigated by higher phosphate (Pi) availability. Under the studied conditions, As+5 removal efficiency of HRs greatly exceeded that of seedlings. Further, tobacco HRs were able to accumulate As in their tissues. These results justify further investigations on As tolerance and detoxification mechanisms in tobacco, an easy-to-transform crop species with high biomass, which could allow evaluation of the possible application of wild type or alternatively transgenic tobacco plants for As phytoextraction.",
Arsenic,1015779,"Measuring hypoxia induced metal release from highly contaminated estuarine sediments during a 40 day laboratory incubation experiment Abstract: Nutrient inputs to estuarine and coastal waters worldwide are increasing and this in turn is increasing the prevalence of eutrophication and hypoxic and anoxic episodes in these systems. Many urbanised estuaries are also subject to high levels of anthropogenic metal contamination. Environmental O(2) levels may influence whether sediments act as sinks or sources of metals. In this study we investigated the effect of an extended O(2) depletion event (40 days) on fluxes of trace metals (and the metalloid As) across the sediment-water interface in sediments from a highly metal contaminated estuary in S.E. Tasmania, Australia. We collected sediments from three sites that spanned a range of contamination and measured total metal concentration in the overlying water using sealed core incubations. Manganese and iron, which are known to regulate the release of other divalent cations from sub-oxic sediments, were released from sediments at all sites as hypoxia developed. In contrast, the release of arsenic, cadmium, copper and zinc was comparatively low, most likely due to inherent stability of these elements within the sediments, perhaps as a result of their refractory origin, their association with fine-grained sediments or their being bound in stable sulphide complexes. Metal release was not sustained due to the powerful effect of metal-sulphide precipitation of dissolved metals back into sediments. The limited mobilisation of sediment bound metals during hypoxia is encouraging, nevertheless the results highlight particular problems for management in areas where hypoxia might occur, such as the release of metals exacerbating already high loads or resulting in localised toxicity.",
Arsenic,1508700,"Trichoderma inoculation ameliorates arsenic induced phytotoxic changes in gene expression and stem anatomy of chickpea (Cicer arietinum) Abstract: Arsenic, a carcinogenic metalloid severely affects plant growth in contaminated areas. Present study shows role of Trichoderma reesei NBRI 0716 (NBRI 0716) in ameliorating arsenic (As) stress on chickpea under greenhouse conditions. Arsenic stress adversely affected seed germination (25%), chlorophyll content (44%) and almost eliminated nodule formation that were significantly restored on NBRI 0716 inoculation. It also restored stem anomalies like reduced trichome turgidity and density, deformation in collenchymatous and sclerenchymatous cells induced by As stress. Semi-quantitative RT-PCR of stress responsive genes showed differential expression of genes involved in synthesis of cell wall degrading enzymes, dormancy termination and abiotic stress. Upregulation of drought responsive genes (DRE, EREBP, T6PS, MIPS, and PGIP), enhanced proline content and shrunken cortex cells in the presence of As suggests that it creates water deficiency in plants and these responses were modulated by NBRI 0716 which provides a protective role. NBRI0716 mediated production of As reductase enzyme in chickpea and thus contributed in As metabolism. The study suggests a multifarious role of NBRI0716 in mediating stress tolerance in chickpea towards As.",
Arsenic,2278606,"Assessment of air pollution originating from copper smelter in Bor (Serbia) Abstract: Air quality monitoring was performed at the measuring sites in the urban-industrial and suburban zone during the period 2005-2007 in Bor (Serbia). Arsenic, lead, cadmium, copper and sulphur dioxide are predominantly of industrial origin as a result of copper production in the study area. The smelter, which is a part of the Mining-Metallurgical Complex Bor, is the major pollution source. As and SO2 are the pollutants which pose the biggest threat for the inhabitants of the Bor area, since the measured concentrations exceed the proposed limit values. The obtained concentrations showed that the endangered areas are in close vicinity of the smelter, as well as in the directions of the prevailing winds. By grouping these pollutants into separate clusters, the results of cluster analysis confirmed high loads of As and SO2 in the air. The results of principal component analysis showed that copper production has major influence on air pollution.",
Arsenic,2102,"Chemical quality of maternal drinking water and congenital heart disease Abstract: We undertook a case-control study to investigate the association between chemicals in maternal drinking water consumed during pregnancy and congenital heart disease in the offspring. Two hundred and seventy affected children and 665 healthy children were enrolled in the study. Information on contaminant levels in maternal drinking water was available from records of routine water analysis of samples taken from public taps in the communities where the mothers resided during pregnancy. Mothers provided information during a telephone interview on their health, pregnancy management, and demographic characteristics. Nine inorganic metals were analysed for detection of an association with congenital heart disease. The chemical exposures of particular interest were arsenic, lead, mercury and selenium. None of the chemicals was associated materially with an increase in the frequency of congenital heart disease overall. Arsenic exposure at any detectable level was associated with a threefold in-cre 3se in occurence of coarctation of the aorta (prevalence odds ratio = 3.4,95% confidence interval = 1.3-8.9). Detectable tracesof selenium in drinking water were associated with a lower frequency of any congenital heart disease than was observed among children exposed to drinking water not containing detectable levels of selenium (prevalence odds ratio = 0.62,95% confidence limits = 0.40-0.97). A dose-response effect was observed over four levels of selenium exposure. Non-differential errors in the measurement and classification of exposure to contaminants routinely monitored in drinking water could account for lack of positive findings. In addition, most of the contaminant levels were below the maximum levels set by the Environmental Protection Agency, so that lack of evidence of effect may have been due to the low exposure levels in this population.",
Arsenic,1677559,"Biogeochemical patterns in a river network along a land use gradient Abstract: The Bode catchment (Germany) shows strong land use gradients from forested parts of the National Park (23 % of total land cover) to agricultural (70 %) and urbanised areas (7 %). It is part of the Terrestrial Environmental Observatories of the German Helmholtz association. We performed a biogeochemical analysis of the entire river network. Surface water was sampled at 21 headwaters and at ten downstream sites, before (in early spring) and during the growing season (in late summer). Many parameters showed lower concentrations in headwaters than in downstream reaches, among them nutrients (ammonium, nitrate and phosphorus), dissolved copper and seston dry mass. Nitrate and phosphorus concentrations were positively related to the proportion of agricultural area within the catchment. Punctual anthropogenic loads affected some parameters such as chloride and arsenic. Chlorophyll a concentration and total phosphorus in surface waters were positively related. The concentration of dissolved organic carbon (DOC) was higher in summer than in spring, whereas the molecular size of DOC was lower in summer. The specific UV absorption at 254 nm, indicating the content of humic substances, was higher in headwaters than in downstream reaches and was positively related to the proportion of forest within the catchment. CO2 oversaturation of the water was higher downstream compared with headwaters and was higher in summer than in spring. It was correlated negatively with oxygen saturation and positively with DOC concentration but negatively with DOC quality (molecular size and humic content). A principle component analysis clearly separated the effects of site (44 %) and season (15 %), demonstrating the strong effect of land use on biogeochemical parameters.",
Arsenic,1339734,"Efflux of glutathione and glutathione complexes from human erythrocytes in response to vanadate Abstract: The main objective of the present study was to investigate if vanadate is extruded from the cells in a glutathione dependent manner resulting in the appearance of extracellular glutathione and complexes of glutathione with vanadium. Vanadate significantly depleted intracellular non-protein sulfhydryl (NPSH) levels in a time- and concentration-dependent manner. The intracellular NPSH level was decreased to 0.0±0.0 ?mol/ml erythrocyte when exposed to 10mM of vanadate for 4h. Extracellular NPSH level was increased concomitantly with the intracellular decrease and reached to 0.1410±0.005 ?mol/ml erythrocyte in 4 h. Intracellular decrease and extracellular increase in NPSH levels were significantly inhibited in the presence of DIDS, a chloride-bicarbonate exchanger which also mediates phosphate and arsenate transport in erythrocytes. In parallel with the increase in extracellular NPSH levels, significant increases in extracellular glutathione levels were detected following exposure to vanadate. Extracellular glutathione levels reached to 0.0150±0.0.001, 0.0330±0.001, and 0.0576±0.002 ?mol/ml erythrocyte with 1, 5, and 10 mM of vanadate respectively. Dimercaptosuccinic acid treatment of supernatants significantly increased the glutathione levels measured in the extracellular media. Utilization of MK571 an MRP inhibitor decreased the rate of glutathione efflux from erythrocytes suggesting a role for this membrane transporter in the process. A known methylation inhibitor periodate oxidized adenosine decreased the rate of glutathione efflux from erythrocytes. This observed decrease in extracellular GSH levels suggests that GSH release partly requires a proper cellular methylation process and that part of GSH detected in the extracellular media may arise from GSH-vandium complexes. The results of the present study indicate that human erythrocyte efflux glutathione in reduced free form and in conjugated form/s that can be recovered with dimercaptosuccinic acid when exposed to vanadate.",
Arsenic,1936189,"Procedia Earth and Plantetary Science Provenance and paleoenvironment impact on arsenic accumulation in aquifer sediments from the Datong Basin, China: implications from element geochemistry Abstract: ",
Arsenic,2278967,"Distribution characteristics and ecological risk assessment of toxic heavy metals and metalloid in surface water of lakes in Daqing Heilongjiang Province, China Abstract: It is necessary to estimate heavy metal concentrations and risk in surface water for understanding the heavy metal contaminations and for sustainable protection of ecosystems and human health. To investigate the anthropogenic contribution of heavy metal accumulation surrounding an industrial city in China, the concentrations of six heavy metals, including mercury (Hg), arsenic (As), chromium (Cr), lead (Pb), copper (Cu), and cadmium (Cd) were examined; from four different regions of Daqing in autumn 2011 and winter 2012. The results showed heavy metals distributed in the industrial area at concentrations relatively higher than those in other three areas, while concentrations in the farming area and the protected area were lower. The heavy metal concentrations of water bodies in all areas, except those for Hg and As, Cu, Pb and Cr were lower than the cutoff values for the Class I water quality that was set as the highest standard to protect the national nature reserves. While Hg and As of lakes in industry region had a higher level than those in the agriculture and landscape water, the lowest allowed. The concentrations of all the heavy metals in winter were higher than in the autumn. Cu had a higher ecological risks level to freshwater organisms. The discharge of urban sewage and industrial wastewater might be a major pollutant source, thus these sources should identified before remediation efforts. Efforts are needed to protect the lakes from pollution and also to reduce environmental health risks. This study and the valuable data will pave the way for future research on these Lakes in Daqing.",
Arsenic,1508518,"Microbial communities in low-permeability, high pH uranium mine tailings: Characterization and potential effects Abstract: AIMS: To describe the diversity and metabolic potential of microbial communities in uranium mine tailings characterized by high pH, high metal concentration and low permeability. METHODS AND RESULTS: To assess microbial diversity and their potential to influence the geochemistry of uranium mine tailings using aerobic and anaerobic culture-based methods, in conjunction with next generation sequencing and clone library sequencing targeting two universal bacterial markers (16S rRNA and cpn60 genes. Growth assays revealed that 69% of the 59 distinct culturable isolates evaluated were multiple-metal resistant, with 15% exhibiting dual-metal hypertolerance. There was a moderately-positive correlation coefficient (R=0.43, p &lt; 0.05) between multiple-metal resistance of the isolates and their enzyme expression profile. Of the isolates tested, 17 reduced amorphous iron, 22 reduced molybdate, and 7 oxidized arsenite. Based on next generation sequencing, tailings-depth was shown to influence bacterial community composition, with the difference in the microbial diversity of the upper (0-20 m) and middle (20-40 m) tailings zones being highly-significant (p &lt; 0.01) from the lower zone (40-60 m) and the difference in diversity of the upper and middle tailings zone being significant (p &lt; 0.05). Phylotypes closely-related to well-known sulfate and iron reducing bacteria were identified with low abundance, yet relatively-high diversity. CONCLUSIONS: The presence of a population of metabolically-diverse, metal-resistant microorganisms within the tailings environment, along with their demonstrated capacity for transforming metal elements, suggests that these organisms have the potential to influence the long term geochemistry of the tailings.",
Arsenic,1027255,"Desorption of arsenic from drinking water distribution system solids Abstract: Previous work has shown that arsenic can accumulate in drinking water distribution system (DWDS) solids (Lytle et al., 2004) when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers' tap. The primary objective of this work was to examine the impact of pH and orthophosphate on the chemical release (i.e. desorption) of arsenic from nine DWDS solids collected from utilities located in the Midwest. Arsenic release comparisons were based on the examination of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168 hours. Results showed that arsenic was released from solids and suggested that arsenic release was a result of desorption rather than dissolution. Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in the test range of 7 to 9). Finally, orthophosphate (3 and 5 mg PO4/L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting in elevated levels at the consumer's tap.",
Arsenic,1019938,"Low serum carotene level and increased risk of ischemic heart disease related to long-term arsenic exposure Abstract: To elucidate the association between arsenic-related ischemic heart disease (ISHD) and serum antioxidant micronutrient level, residents aged 30 or older living in arseniasis-hyperendemic villages in Taiwan were recruited in a community-based health survey. A structured questionnaire was used to obtain a history of long-term exposure to arsenic through consuming artesian well water and fasting serum samples were also collected at the recruitment. A total of 74 patients affected with ISHD, who were diagnosed through both electrocardiography and Rose questionnaire interview, and 193 age-sex-matched healthy controls were selected for the examination of serum levels of micronutrients by high performance liquid chromatography (HPLC). There was a significant biological gradient between the risk of ISHD and the duration of consuming high-arsenic artesian well water. A significant reverse dose-response relationship with arsenic-related ISHD was observed for serum level of alpha- and beta-carotene, but not for serum levels of retinol, lycopene and alpha-tocopherol. Multivariate analysis showed a synergistic interaction on arsenic-related ISHD between duration of consuming artesian well water and low serum carotene level. An increased risk of arsenic-related ISHD was also associated with hypertension and elevated body mass index, but not with serum lipid profile, cigarette smoking and alcohol drinking. The findings seem to suggest that arsenic-related ISHD has a pathogenic mechanism which is at least partially different from that of ISHD unrelated to long-term exposure to arsenic.",
Arsenic,1252445,"Interaction between some common genotoxic agents Abstract: The clastogenic effects of arsenic, lead and sulphur dioxide and the protective effect of selenium were studied in short-term lymphocyte cultures. The three agents selected are the major toxic substances in emissions from copper smelters. Cells from non-smoking, healthy individuals were exposed to individual agents and combinations of the four agents (sodium arsenite, lead acetate, sodium sulphite and sodium selenite) and the cells were analysed for chromosome aberrations and sister chromatide exchanges. Selenium showed an antagonistic (protective) effect against the other agents. No synergistic effects were found, and the interactions between arsenic, lead and sulphur dioxide were mainly antagonistic. These rather unexpected findings indicate that mixed exposure from copper smelters, and other mixed exposures where arsenic, lead and sulphur dioxide are involved, may cause less genetic damage than expected and that an adequate dietary supplement of selenium may reduce the genotoxic effects of these agents.",
Arsenic,1022505,"Association between arsenic exposure from a coal-burning power plant and urinary arsenic concentrations in Prievidza District, Slovakia Abstract: To assess the arsenic exposure of a population living in the vicinity of a coal-burning power plant with high arsenic emission in the Prievidza District, Slovakia, 548 spot urine samples were speciated for inorganic As (Asinorg), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and their sum (Assum). The urine samples were collected from the population of a case-control study on nonmelanoma skin cancer (NMSC). A total of 411 samples with complete As speciations and sufficient urine quality and without fish consumption were used for statistical analysis. Although current environmental As exposure and urinary As concentrations were low (median As in soil within 5 km distance to the power plant, 41 micro g/g; median urinary Assum, 5.8 microg/L), there was a significant but weak association between As in soil and urinary Assum(r = 0.21, p < 0.01). We performed a multivariate regression analysis to calculate adjusted regression coefficients for environmental As exposure and other determinants of urinary As. Persons living in the vicinity of the plant had 27% higher Assum values (p < 0.01), based on elevated concentrations of the methylated species. A 32% increase of MMA occurred among subjects who consumed homegrown food (p < 0.001). NMSC cases had significantly higher levels of Assum, DMA, and Asinorg. The methylation index Asinorg/(MMA + DMA) was about 20% lower among cases (p < 0.05) and in men (p < 0.05) compared with controls and females, respectively.",
Arsenic,1347691,"Asymmetric synthesis of enaminophosphines via palladacycle-catalyzed addition of Ph2PH to ?,?-unsaturated imines Abstract: A highly reactive, chemo- and enantioselective addition of diphenylphosphine to ?,?-unsaturated imines catalyzed by a palladacycle has been developed, thus providing the access to a series of chiral tertiary enaminophosphines in high yields. A putative catalytic cycle has also been proposed.",
Arsenic,1597454,"Antimony resistance and environment: Elusive links to explore during Leishmania life cycle Abstract: Leishmania drug resistance and particularly antimony resistance still continues to emerge in different part of the world. Because visceral and cutaneous leishmaniasis are transmitted in foci with zoonotic or anthroponotic life-cycles, the link between chemotherapeutic resistance and the selection for drug resistance, through drug consumption, cannot be as obvious for all forms of leishmaniasis. The underlying factors that trigger the selection of antimony resistant parasites are poorly studied in regard to environmental aspects. Recently, a correlation between the emergence of antimony unresponsiveness in India and water arsenic contamination has been raised. The presence of some yet unidentified environmental factors driving the selection of antimony resistant Leishmania populations in a zoonotic context of leishmaniasis is also currently questioned. The identification of key molecules involved in the selection of antimony resistance and their importance in the selective process have to be re-evaluated in light of the environment were all the hosts of Leishmania (mammalian and arthropod) evolved. These new insights will help to (i) address the risk of therapeutic failure associated with the emergence of drug-resistance and (ii) propose new therapeutic protocols to aim at reducing the risk of resistance in endemic areas. (C) 2012 Published by Elsevier Ltd. on behalf of Australian Society for Parasitology Inc.",
Arsenic,1018419,"Reactive oxygen species do not cause arsine-induced hemoglobin damage Abstract: Previous work suggested that arsine- (AsH3-) induced hemoglobin (HbO2) damage may lead to hemolysis (Hatlelid et al., 1996). The purpose of the work presented here was to determine whether reactive oxygen species are formed by AsH3 in solution, in hemoglobin solutions, or in intact red blood cells, and, if so, to determine whether these species are responsible for the observed hemoglobin damage. Hydrogen peroxide (H2O2) was detected in aqueous solutions containing AsH3 and HbO2 or AsH3 alone but not in intact red blood cells or lysates. Additionally, high-activity catalase (19,200 U/ml) or glutathione peroxidase (68 U/ml) added to solutions of HbO2 and AsH3 had only a minor protective effect against AsH3-induced damage. Further, the differences between the visible spectra of AsH3-treated HbO2 and H2O2-treated HbO2 indicate that two different degradative processes occur. The presence of superoxide anion (O2-) was measured by O2(-)-dependent reduction of nitro blue tetrazolium (NBT). The results were negative for O2-. Exogenous superoxide dismutase (100 micrograms/ml) did not affect AsH3-induced HbO2 spectral changes, nor did the hydroxyl radical scavengers, mannitol, and DMSO (20 mM each). The general antioxidants ascorbate (&lt; or = 10 mM) and glutathione (&lt; or = 1 mM) also had no effect. These results indicate that the superoxide anion and the hydroxyl radical (OH) are not involved in the mechanism of AsH3-induced HbO2 damage. The results also indicate that although AsH3 contributes to H2O2 production in vitro, cellular defenses are adequate to detoxify the amount formed. An alternative mechanism by which an arsenic species is the hemolytic agent is proposed.",
Arsenic,1340132,"Effect of different arbuscular mycorrhizal fungal isolates on growth and arsenic accumulation in Plantago lanceolata L Abstract: The role of indigenous and non-indigenous arbuscular mycorrhizal fungi (AMF) on As uptake by Plantago lanceolata L. growing on substrate originating from mine waste rich in As was assessed in a pot experiment. P. lanceolata inoculated with AMF had higher shoot and root biomass and lower concentrations of As in roots than the non-inoculated plants. There were significant differences in As concentration and uptake between different AMF isolates. Inoculation with the indigenous isolate resulted in increased transfer of As from roots to shoots; AMF from non-polluted area apparently restricted plants from absorbing As to the tissue; and plants inoculated with an AMF isolate from Zn-Pb waste showed strong As retainment within the roots. Staining with dithizone indicated that AMF might be actively involved in As accumulation. The mycorrhizal colonization affected also the concentration of Cd and Zn in roots and Pb concentration, both in shoots and roots.",
Arsenic,2149165,"Radioprotection and cell cycle arrest of intestinal epithelial cells by darinaparsin, a tumor radiosensitizer Abstract: <strong>PURPOSE: </strong>It was recently reported that the organic arsenic compound darinaparsin (DPS) is a cytotoxin and radiosensitizer of tumor cells in vitro and in subcutaneous xenograft tumors. Surprisingly, it was also found that DPS protects normal intestinal crypt epithelial cells (CECs) from clonogenic death after ionizing radiation (IR). Here we tested the DPS radiosensitizing effect in a clinically relevant model of prostate cancer and explored the radioprotective effect and mechanism of DPS on CECs.<br /><br /><strong>METHODS AND MATERIALS: </strong>The radiation modification effect of DPS was tested in a mouse model of orthotopic xenograft prostate cancer and of IR-induced acute gastrointestinal syndrome. The effect of DPS on CEC DNA damage and DNA damage responses was determined by immunohistochemistry.<br /><br /><strong>RESULTS: </strong>In the mouse model of IR-induced gastrointestinal syndrome, DPS treatment before IR accelerated recovery from body weight loss and increased animal survival. DPS decreased post-IR DNA damage and cell death, suggesting that the radioprotective effect was mediated by enhanced DNA damage repair. Shortly after DPS injection, significant cell cycle arrest was observed in CECs at both G1/S and G2/M checkpoints, which was accompanied by the activation of cell cycle inhibitors p21 and growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A). Further investigation revealed that DPS activated ataxia telangiectasia mutated (ATM), an important inducer of DNA damage repair and cell cycle arrest.<br /><br /><strong>CONCLUSIONS: </strong>DPS selectively radioprotected normal intestinal CECs and sensitized prostate cancer cells in a clinically relevant model. This effect may be, at least in part, mediated by DNA damage response activation and has the potential to significantly increase the therapeutic index of radiation therapy.",
Arsenic,1017067,"c-Src-dependent activation of the epidermal growth factor receptor and mitogen-activated protein kinase pathway by arsenic. Role in carcinogenesis Abstract: Environmental or occupational exposure to arsenic is associated with a greatly increased risk of skin, urinary bladder, and respiratory tract cancers in arseniasis-endemic areas throughout the world. Arsenic shares many properties of tumor promoters by affecting specific cell signal transduction pathways responsible for cell proliferation. The activation of the epidermal growth factor receptor (EGFR)-extracellular signal-regulated protein kinase (ERK) pathway is important in mediating gene expression related to regulation of cellular growth. In the current studies, we demonstrate that arsenic activates EGFR and ERK in a human uroepithelial cell line. The EGFR phosphorylation by arsenic is ligand-independent and does not involve the major autophosphorylation site Tyr(1173). c-Src activity is also induced by arsenic and is a prerequisite for the EGFR and ERK activation. Consistent with these in vitro observations, exposure of mice to arsenic in drinking water, which has been found previously to be associated with AP-1 activation and epithelial proliferation, induces EGFR and ERK activation in the urinary bladder. This response is also accompanied with an increase in c-Src levels interacting with EGFR. These findings represent a potential pathway for mediating arsenic-induced phenotypic changes in the uroepithelium.",
Arsenic,1016191,"Development of arsenic testing field kit--a tool for rapid on-site screening of arsenic contaminated water sources Abstract: Recognizing the enormity and severity of the problem of arsenic poisoning in ground water, the capabilities of commercially available arsenic detection field kits were critically evaluated. In the light of findings of the evaluation of these kits, their merits and limitations; a simple, efficient, prudent, userfriendly, indigenous field kit has been developed. The kit can be used for rapid on-site screening of arsenic contaminated water sources and is capable of detecting arsenic concentration as low as 0.01 mg L(-1), the guideline value for arsenic set by the WHO. The kit has been subjected to extensive laboratory and field testing. The details of development of the kit and its salient features are presented in the paper.",
Arsenic,1017163,"Arsenic tolerances in rice (Oryza sativa) have a predominant role in transcriptional regulation of a set of genes including sulphur assimilation pathway and antioxidant system Abstract: World wide arsenic (As) contamination of rice has raised much concern as it is the staple crop for millions. Four most commonly cultivated rice cultivars, Triguna, IR-36, PNR-519 and IET-4786, of the West Bengal region were taken for a hydroponic study to examine the effect of arsenate (As(V)) and arsenite (As(III)) on growth response, expression of genes and antioxidants vis-à-vis As accumulation. The rice genotypes responded differentially under As(V) and As(III) stress in terms of gene expression and antioxidant defences. Some of the transporters were up-regulated in all rice cultivars at lower doses of As species, except IET-4786. Phytochelatin synthase, GST and ?-ECS showed considerable variation in their expression pattern in all genotypes, however in IET-4786 they were generally down-regulated in higher As(III) stress. Similarly, most of antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) increased significantly in Triguna, IR-36 and PNR-519 and decreased in IET-4786. Our study suggests that Triguna, IR-36 and PNR-519 are tolerant rice cultivars accumulating higher arsenic; however IET-4786 is susceptible to As-stress and accumulates less arsenic than other cultivars.",
Arsenic,1029584,"Chemistry of Bowen's disease: Relationship to arsenic Abstract: Analytical determination of arsenic (7440382) content in cutaneous lesions of Bowen's disease from 50 cancer patients was performed to determine the relationship of arsenic to Bowen's disease and the associated internal cancer. A significant proportion of Bowen's disease patients had increased amount of arsenic in lesions and in the adjacent skin than did the control patients, with the Bowen's lesions concentrating arsenic more than did the normal adjacent skin and the control lesions. Histopathological changes were of value in determining possible histogenesis and pathogenesis of the Bowen's lesions. The results suggest that arsenic could be one of the causes of Bowen's disease, and that internal and cutaneous cancer present in the patients may be a systemic manifestation of the carcinogen.",
Arsenic,1798802,The Lewis base stabilized parent arsanylborane H2 AsBH2 ?NMe3 Abstract: Exclusively hydrogen substituted arsanylboranes: The synthesis of the unprecedented Lewis base stabilized monomeric parent compound of the arsanylborane H2 AsBH2 ?NMe3 was achieved in a one-pot reaction in high yield and purity. The analogous phosphanylborane was synthesized in a similar manner. A series of different reactions was performed on H2 AsBH2 ?NMe3 to show its broad reactivity pattern.,
Arsenic,627579,"Polymorphism in the ERCC2 codon 751 is associated with arsenic-induced premalignant hyperkeratosis and significant chromosome aberrations Abstract: In West Bengal, India more than 6 million people are exposed to high levels of arsenic through drinking water. Since, only 15-20% of the exposed individuals show arsenic-induced skin lesions, it is assumed that genetic variation might play an important role in arsenic toxicity and carcinogenicity. Arsenic exposure often leads to the development of hyperkeratosis, the precursor of arsenic-induced skin cancer. ERCC2 (excision repair cross-complementing rodent repair deficiency, complementation group 2) is a nucleotide excision repair pathway gene, and its SNPs have been implicated in several types of epithelial cancers. We investigated the possible association of ERCC2 codon 751 A-->C polymorphism (lysine to glutamine) with arsenic-induced hyperkeratosis and correlated ERCC2 genotypes with increased frequencies of chromosomal aberration to ascertain whether any genotype leads to sub-optimal DNA repair. For this association study, 318 unrelated arsenic exposed subjects (165 with hyperkeratosis and 153 without any arsenic-induced skin lesions), drinking water contaminated with arsenic to a similar extent, were recruited. Genotyping was done through PCR-RFLP procedure. Lys/Lys genotype was significantly over-represented in the arsenic-induced hyperkeratosis-exhibiting group [odds ratio (OR) = 4.77, 95% confidence interval (CI) = 2.75-8.23]. A statistically significant increase in both CA/cell and percentage of aberrant cells was observed in the individuals with AA genotype compared to those with AC or CC genotype combined (P < 0.01) in each of the two study groups, as also, in the total study population. This study indicates that ERCC2 codon 751 Lys/Lys genotype is significantly associated with arsenic-induced premalignant hyperkeratosis and is possibly due to sub-optimal DNA repair capacity of the ERCC2 codon 751 Lys/Lys genotype.",
Arsenic,1070483,"The characteristics of waste Saccharomyces cerevisiae biosorption of arsenic(III) Abstract: PURPOSE: The potential of using waste Saccharomyces cerevisiae as adsorbent for the adsorption of As(III) from aqueous solution was assessed. METHODS: The biosorbent was characterized by Fourier transform infrared (FTIR) spectroscopy analysis. Various parameters including pH, biosorbent dosage, contact time, and temperature were systematically investigated. RESULTS AND CONCLUSIONS: The FTIR results of S. cerevisiae biomass showed that biomass has different functional groups, and these functional groups are able to react with metal ion in aqueous solution. Several biosorption isotherms were used to fit the equilibrium data, showing sorption to be monolayer on the heterogeneous surface of the biosorbent. The maximum biosorption capacity calculated using Langmuir model was found to be 62.908 ?g/g at pH 5.0, biosorbent dosage 5 g/L, contact time 240 min, and temperature 35 °C. The kinetic studies indicated that the biosorption process of the As(III) followed well the pseudo-second-order equation. The intraparticle diffusion and Richenberg models were applied to the data, and we found that the biosorption of As(III) was governed by film diffusion followed by intraparticle diffusion. The thermodynamics constants indicated that the biosorption of As(III) onto S. cerevisiae was spontaneous and endothermic under examined conditions. Biosorbent could be regenerated using 0.5 M NaOH solution, with up to 75 % recovery.",
Arsenic,2278872,"ERCC1 expression as a predictor of resistance to platinum-based chemotherapy in primary ovarian cancer Abstract: <strong>AIM: </strong>The purpose of the present study was to investigate the possible association between Excision repair cross-complementing group 1 (ERCC1) score and platinum resistance in first-line chemotherapy for ovarian cancer.<br /><br /><strong>PATIENTS AND METHODS: </strong>ERCC1 Expression was determined using immunohisto-chemistry in 68 patients with platinum-responding tumor and 30 with platinum-resistant tumors. The primary end-point of this study was the association between the expression of ERCC1 protein with resistance to standard platinum-based chemotherapy in primary ovarian cancer.<br /><br /><strong>RESULTS: </strong>In pairwise comparisons, the overall survival (OS) for patients with ovarian cancer, who were non-responders to platinum-based chemotherapy with low or intermediate H-score for ERCC1 was better than that of non-responders with high H-score for ERCC1 [median OS=21 (16.8-25.2 months) and 28 (14.6-41.4 months) vs. 15 months (6.2-23.8 months), p-value=0.048, and p-value=0.017, respectively].<br /><br /><strong>CONCLUSION: </strong>There were no significant differences in the progression-free survival between those with low, intermediate and high H-score for ERCC1. There is no statistically significant relationship between ERCC1 score and response to platinum-based chemotherapy in patients with primary ovarian cancer.",
Arsenic,1936143,Metallic Iron for Water Treatment: A Critical Review Abstract: ,
Arsenic,62134,"Arsenic exposure to smelter workers: Clinical and neurophysiological studies Abstract: Forty-seven copper smelter workers, exposed to airborne arsenic for 8-40 years, were examined clinically with electromyography, and the motor and sensory conduction velocities in their arms and legs were determined. Fifty age-matched industrial workers not exposed to arsenic formed a reference group. The level of arsenic in the air at the smeltery was estimated to be below 500 micrograms/m3 before 1975 and approximately 50 micrograms/m3 thereafter. Urine analyses of arsenic showed a mean value of 71 micrograms/l (1 mumol/l) in the exposed group; this value is lower than that found in earlier studies reporting clinically detectable neuropathy. Only minor neurological and electromyographic abnormalities were found. A slightly reduced nerve conduction velocity in two or more peripheral nerves was more common among the arsenic workers than the referents, and a statistically significant correlation between cumulative exposure to arsenic and reduced nerve conduction velocity in three peripheral motor nerves was found. This occurrence was interpreted as a sign of slight subclinical neuropathy. In conclusion the risk of clinically significant neuropathy is small when exposure is kept below 50 micrograms/m3 in workroom air. The subclinical findings may be of interest in relation to the prevention of early adverse health effects from arsenic exposure.",
Arsenic,530289,"Arsenic-induced toxicity: effect on protein composition in sciatic nerve Abstract: Exposure to arsenic compounds may lead to skin and lung cancer and various disorders such as vascular disease and peripheral neuropathy in humans. Peripheral arsenic neurotoxicity has been demonstrated clinically and in electrophysiological studies. Patients intoxicated with arsenic show neurological symptoms in their feet and hands. These patients show significantly lower nerve conduction velocities (NCVs) in their peripheral nerves in comparison with controls. The mechanism of arsenic peripheral nervous system (PNS) toxicity, however, has never been described before. This is the first study to investigate the toxicity of arsenic on the PNS. Male Wistar rats were exposed to arsenite given as a single dose i.v. After sacrifice, sciatic nerves were excised and the protein composition was analysed. Protein analysis of sciatic nerves showed disappearance of neurofilament and fibroblast proteins in rats treated with arsenite doses of 15 and 20 mg/kg in comparison with the control groups. Some fibroblast protein bands had disappeared in the 20-mg/kg dose group. The analysed neurofilament-M and -L proteins decreased dose dependency over time. arsenic affects the composition of proteins in the rat sciatic nerve, especially the neurofilaments. The reduction of signals in Western blot analysis reveals changes in cytoskeletal composition, which may well lead to neurotoxic effects in vivo.",
Arsenic,1579241,"Phosphorus-arsenic interactions in variable-charge soils in relation to arsenic mobility and bioavailability Abstract: Phosphorus (P) influences arsenic (As) mobility and bioavailability which depends on the charge components of soil. The objective of this study was to examine P-As interaction in variable-charge allophanic soils in relation to P-induced As mobilization and bioavailability. In this work, the effect of P on arsenate [As(V)] adsorption and desorption was examined using a number of allophanic and non-allophanic soils which vary in their anion adsorption capacity. The effect of P on As uptake by Indian mustard (Brassica juncea L.) plants was examined using a solution culture, and a soil plant growth experiment involving two As-spiked allophanic and non-allophanic soils which vary in their anion adsorption capacity, and a field As-contaminated sheep dip soil. Arsenate adsorption increased with an increase in the anion adsorption capacity of soils. The addition of P resulted in an increase in As desorption, and the effect was more pronounced in the case of allophanic soil. In the case of both As-spiked soils and field contaminated sheep-dip soil, application of P increased the desorption of As, thereby increasing its bioavailability. The effect of P on As uptake was more pronounced in the high anion adsorbing allophanic than low adsorbing non-allophanic soil. In the case of solution culture, As phytoavailability decreased with increasing concentration of P which is attributed to the competition of P for As uptake by roots. While increasing P concentration in solution decreased the uptake of As, it facilitated the translocation of As from root to shoot. The net effect of P on As phytoavailability in soils depends on the extent of P-induced As mobilization in soils and P-induced competition for As uptake by roots. The P-induced mobilization of As could be employed in the phytoremediation of As-contaminated sites. However, care must be taken to minimize the leaching of As mobilized through the P-induced desorption, thereby resulting in groundwater and off site contamination.",
Arsenic,1020188,"Endonuclease III, formamidopyrimidine-DNA glycosylase, and proteinase K additively enhance arsenic-induced DNA strand breaks in human cells Abstract: We report here that sequential digestion with endonuclease III, formamidopyrimidine-DNA glycosylase, and proteinase K in Tris buffer markedly increased the sensitivity for detecting DNA damage in arsenic-treated cells. These three enzymes increased DNA strand breaks in an additive manner. By using this sequential-enzyme-digestion comet assay, we demonstrated that trivalent inorganic arsenic induced more DNA damage than monomethylarsonous acid, monomethylarsonic acid, and dimethylarsinic acid in human blood cell lines. However, trivalent inorganic arsenic was far less potent than monomethylarsonous acid in inhibiting pyruvate dehydrogenase activity. Therefore, different mechanisms are involved in inhibiting pyruvate dehydrogenase activity and inducing DNA damage. Our results also indicate while trivalent inorganic arsenic induced more endonuclease III-digestible adducts, monomethylarsonous acid and monomethylarsonic acid induced more proteinase K-digestible adducts. These results suggest there is a difference in the mechanism for inducing DNA damage between inorganic and organic methylated arsenic compounds.",
Arsenic,1020632,"Suppression of Fas ligand expression on endothelial cells by arsenite through reactive oxygen species Abstract: Chronic exposure to arsenite is associated with vascular disease, such as arteriosclerosis. However, the cellular mechanisms for vascular disease in response to arsenic are not well known. The present study has demonstrated that arsenite not arsenate decreased the Fas ligand (FasL) expression on ECV304 cells through reactive oxygen species. Incubation of ECV304 cells with arsenite decreased the FasL expression and increased the intracellular peroxide levels. In addition, hydrogen peroxide was found to suppress FasL expression in a dose-dependent manner. The antioxidant, N-acetyl-cysteine, blocked the suppression of FasL expression in response to arsenite. These data suggested that arsenite initiates endothelium dysfunction, at least partly, by suppressing the FasL expression through activating reactive oxygen species sensitive endothelial cell signaling.",
Arsenic,1936093,"Micro x-ray absorption spectroscopic analysis of arsenic localization and biotransformation in Chironomus riparius Meigen (Diptera: Chironomidae) and Culex tarsalis Coquillett (Culicidae) Abstract: The distribution and speciation of arsenic (As) were analyzed in individuals of various life stages of a midge, Chironomus riparius, and the mosquito Culex tarsalis exposed to 1000 ?g/l arsenate. X-ray absorption spectroscopy (XAS) revealed that C. riparius larvae accumulate As in their midgut, with inorganic arsenate [As(V)] being the predominant form, followed by arsenite [As(III)] and an As-thiol. Reduced concentrations of As in pupal and adult stages of C. riparius indicate excretion of As between the larval and pupal stages. In adults, As was limited to the thorax, and the predominant form was an As-thiol. In Cx. tarsalis, As was not found in high enough concentrations to determine As speciation, but the element was distributed throughout the larva. In adults, As was concentrated in the thorax and eyes of adults. These results have implications for understanding the biotransformation of As and its movement from aquatic to terrestrial environments.",
Arsenic,628484,"Effects of sodium arsenite exposure on development and behavior in the rat Abstract: Arsenic is an environmental contaminant found in soil, water and air in some zones of the world. It has been widely studied for its effects as a human carcinogenic agent, but few studies have dealt with neurobehavioral effects. In addition, studies of arsenic effects on development have only addressed its effects on embryotoxicity and teratogenicity after a single oral, gavage or intraperitoneal exposure. Among the behavioral alterations reported after intoxication with arsenic are both increased and decreased locomotor activity and learning deficits in a delayed alternation task [Toxicol. Lett. 54 (1990) 345; Bull. Environ. Contam. Toxicol. 50 (1993) 100; Brain Res. Bull. 55 (2001) 301]. To further characterize developmental and behavioral alterations induced by arsenic exposure, Sprague-Dawley rats were exposed to arsenite (36.70 mg arsenic/l in drinking water) from gestation day 15 (GD 15) or postnatal day 1 (PND 1), until approximately 4 months old. The pregnant or lactating dams received either the arsenic solution or regular drinking water and once pups were weaned, they continued receiving the same solution as drinking water. Animals exposed from GD 15 showed increased spontaneous locomotor activity and both exposed groups showed increased number of errors in a delayed alternation task in comparison to the control group. Total arsenic (TA) content in brain was similar for both exposed groups and significantly different from the control group. These results indicate that rats exposed to arsenic during development present deficits in spontaneous locomotor activity and alterations in a spatial learning task.",
Arsenic,1508567,"Bioaccessibility and speciation of arsenic in country foods from contaminated sites in Canada Abstract: Arsenic in foods obtained through foraging or hunting (country foods) in contaminated areas has not been reported; moreover the chemical form (arsenic speciation) is not known. Bioaccessibility extractions can be used to extract the arsenic from samples, giving information about the arsenic that is available for absorption into humans. Bioaccessibility of arsenic was measured in country foods (berries, other plants, mushrooms and hares) collected from contaminated sites in Canada. Arsenic speciation in the bioaccessibility extracts was also determined. Arsenic concentrations in berries ranged from 0.06 to 21mg/kg, and Labrador tea contained 1.9mg/kg of arsenic (all wet weight). Arsenic concentrations (wet weight) ranged up to 46mg/kg in mushrooms, but they were much lower in hare muscle tissue (0.007 to 0.6mg/kg). Percent bioaccessibility was lowest in berries and plants (means of 12-45%), where the arsenic species were mostly toxic inorganic arsenic. Bioaccessibility was higher in mushrooms and hare meat (means of 22-76%), where along with toxic inorganic arsenic, substantial proportions of less toxic organoarsenic species were measured, including non-toxic arsenobetaine. The speciation patterns were highly variable in both mushrooms and hare meat. Toxic forms of arsenic are present in country foods collected from contaminated areas, but the amounts vary according to and within each sample type. Therefore testing should ideally be carried out for new sample types and locations to estimate exposures to humans.",
Arsenic,1070418,"Pre- and postnatal arsenic exposure and body size to two years of age: A cohort study in rural Bangladesh Abstract: Background: Exposure to arsenic via drinking water has been associated with adverse pregnancy outcomes and infant morbidity and mortality. Little is known, however, about effects of arsenic on child growth. Objective: To assess potential effects of early-life arsenic exposure on weight and length of children from birth to 2 years of age. Methods: We followed 2372 infants born in a population-based intervention trial in rural Bangladesh. Exposure was assessed by arsenic concentrations in urine (U-As) of mothers (gestational weeks 8 and 30) and children (18 months old). Child anthropometry was measured monthly in the first year and quarterly in the second. Linear regression models were used to examine associations of U-As (by quintiles) with child weight and length, adjusted for age, maternal BMI, SES, and sex (or stratified by sex). Results: Median (10th-90th percentiles) U-As concentrations were about 80 (25-400) µg/L in the mothers and 34 (12-159) µg/L in the children. Inverse associations of maternal U-As with attained weight and length at 3-24 months were markedly attenuated after adjustment. However, associations of U-As at 18 months with weight and length at 18-24 months were more robust, particularly in girls. Compared to girls in the first quintile of U-As (<16 µg/L), those in the fourth quintile (26-46 µg/L) were almost 300 g lighter and 0.7 cm shorter, and had adjusted odds ratios (95% confidence interval) for underweight and stunting of 1.57 (1.02-2.40) and (1.58 (1.05-2.37), respectively, at 21 months. Conclusions: Postnatal arsenic exposure was associated with lower body weight and length among girls, but not boys.",
Arsenic,2337218,"Investigation of severe water problem in urban areas of a developing country: the case of Dhaka, Bangladesh Abstract: The present study evaluated water supply geochemistry in Dhaka City, Bangladesh, to provide detailed trace level (subppb) water quality data that include major ions, low dissolved oxygen (DO) and toxic trace metals for sustainable development. Dhaka Groundwater, which almost uniformly meets the World Health Organization guideline, has become the preferred source. Due to groundwater depletion and an ever-increasing need to meet water demands by city residents, Dhaka water supply and sewerage authority has initiated the treatment of river water, despite the fact that very little is known about the geochemical structure, and trace metal content in the Dhaka water supply. Major ion composition of water samples was determined, and the results used to generate Stiff diagrams. The diagrams served to visually compare water from different sources based on units of mass/volume. Hydrochemical facies analysis showed supply ground and surface waters are comprised predominately of Ca-Na-Mg-HCO3 and Ca-Na-Mg-HCO3-Cl types. Spatial distribution of ions, and Na/Cl and Na/SiO2 molar ratio indicated that silicate weathering is the dominant geochemical process. Chemical data revealed that toxic Cr metal mobilization is associated with chemical hazards from the leather industry. The vulnerability of deep wells to contamination by As is governed by the geometry of induced groundwater flow paths and the geochemical conditions encountered between the shallow and deep regions of the aquifer. Quantifying total arsenic (As) and As from interlocking geochemical cycles (Fe, Mn) may assist in interpreting As dynamics in Dhaka well water. The surface source water was hypoxic to anoxic low DO associated with very high concentrations of biological oxygen demands, and electrical conductivity compared to industrial and non-industrial urban processes and standard activity guidelines. The results of this study should be applied to future research focused on the potential to improve water quality in urban and surrounding areas.",
Arsenic,1330314,"Urine analysis of patients exposed to phenylarsenic compounds via accidental pollution Abstract: New methods involving high-performance liquid chromatography/inductively coupled plasma mass spectrometry were examined for the determination of phenylarsenic compounds derived from chemical warfare agents. Several methods were examined for the separation of diphenylarsinic acid (DPAA), phenylarsonic acid, phenylmethylarsinic acid (PMAA), phenyldimethylarsine oxide, and diphenylmethylarsine oxide. Analysis of the urine samples of the patients exposed to phenylarsenic compounds indicated that the main phenylarsenic components were DPAA and PMAA; moreover, some unknown arsenicals, which were also found in contaminated groundwater and rice samples, were also detected.",
Arsenic,1794775,"Surface morphology and crystallographic properties of GaAs films grown by the MBE process on vicinal Si(001) substrates Abstract: Using the method of molecular-beam epitaxy, GaAs films are grown on Si substrates tilted from the (001) plane by 6° to the [110] direction. The GaAs films are grown both on Si surfaces terminated by arsenic atoms and on pseudo-morphic GaP/Si layers. The layers of GaAs are nucleated by the method of atomic-layer epitaxy at low temperatures. The resulting structures are found to differ in crystallographic orientation of the GaAs film with respect to the film tilt direction. The structures thus grown are examined by the methods of x-ray diffraction analysis and atomic force microscopy.",
Arsenic,627155,"Laboratory diet profoundly alters gene expression and confounds genomic analysis in mouse liver and lung Abstract: Nutritional studies in laboratory animals have long shown that various dietary components can contribute to altered gene expression and metabolism, but diet alone has not been considered in whole animal genomic studies. In this study, global gene expression changes in mice fed either a non-purified chow or a purified diet were investigated and background metal levels in the two diets were measured by ICP-MS. C57BL/6J mice were raised for 5 weeks on either the cereal-based, non-purified LRD-5001 diet or the purified, casein-based AIN-76A diet, as part of a larger study examining the effects of low dose arsenic (As) in the diet or drinking water. Affymetrix Mouse Whole Genome 430 2.0 microarrays were used to assess gene expression changes in the liver and lung. Microarray analysis revealed that animals fed the LRD-5001 diet displayed a significantly higher hepatic expression of Phase I and II metabolism genes as well as other metabolic genes. The LRD-5001 diet masked the As-induced gene expression changes that were clearly seen in the animals fed the AIN-76A diet when each dietary group was exposed to 100 ppb As in drinking water. Trace metal analysis revealed that the LRD-5001 diet contained a mixture of inorganic and organic As at a total concentration of 390 ppb, while the AIN-76A diet contained approximately 20 ppb. These findings indicate that the use of non-purified diets may profoundly alter observable patterns of change induced by arsenic and, likely, by other experimental treatments, particularly, altering gene and protein expression.",
Arsenic,1021650,"Altered gene expression by low-dose arsenic exposure in humans and cultured cardiomyocytes: assessment by real-time PCR arrays Abstract: Chronic arsenic exposure results in higher risk of skin, lung, and bladder cancer, as well as cardiovascular disease and diabetes. The purpose of this study was to investigate the effects on expression of selected genes in the blood lymphocytes from 159 people exposed chronically to arsenic in their drinking water using a novel RT-PCR TaqMan low-density array (TLDA). We found that expression of tumor necrosis factor-? (TNF-?), which activates both inflammation and NF-?B-dependent survival pathways, was strongly associated with water and urinary arsenic levels. Expression of KCNA5, which encodes a potassium ion channel protein, was positively associated with water and toe nail arsenic levels. Expression of 2 and 11 genes were positively associated with nail and urinary arsenic, respectively. Because arsenic exposure has been reported to be associated with long QT intervals and vascular disease in humans, we also used this TLDA for analysis of gene expression in human cardiomyocytes exposed to arsenic in vitro. Expression of the ion-channel genes CACNA1, KCNH2, KCNQ1 and KCNE1 were down-regulated by 1-?M arsenic. Alteration of some common pathways, including those involved in oxidative stress, inflammatory signaling, and ion-channel function, may underlay the seemingly disparate array of arsenic-associated diseases, such as cancer, cardiovascular disease, and diabetes.",
Arsenic,1597362,"Arsenic removal with composite iron matrix filters in bangladesh: a field and laboratory study Abstract: The main arsenic mitigation measures in Bangladesh, well-switching and deep tube wells, have reduced As exposure, but water treatment is important where As-free water is not available. Zero-valent iron (ZVI) based SONO household filters, developed in Bangladesh, remove As by corrosion of locally available inexpensive surplus iron and sand filtration in two buckets. We investigated As removal in SONO filters in the field and laboratory, covering a range of typical groundwater concentrations (in mg/L) of As (0.14-0.96), Fe (0-17), P (0-4.4), Ca (45-162), and Mn (0-2.8). Depending on influent Fe(II) concentrations, 20-80% As was removed in the top sand layer, but As removal to safe levels occurred in the ZVI-layer of the first bucket. Residual As, Fe, and Mn were removed after re-aeration in the sand of the second bucket. New and over 8-year-old filters removed As to &lt;50 ?g/L and mostly to &lt;10 ?g/L and Mn to &lt;0.2 mg/L. Vertical concentration profiles revealed formation of Fe(II) by corrosion of Fe(0) with O2 and incorporation of As into forming amorphous Fe phases in the composite iron matrix (CIM) of newer filters and predominantly magnetite in older filters. As mass balances indicated that users filtered less than reported volumes of water, pointing to the need for more educational efforts. All tested SONO filters provided safe drinking water without replacement for up to over 8 years of use.",
Arsenic,1031084,"Nondestructive determination of arsenic in urine by epithermal neutron activation analysis and Compton suppression Abstract: Epithermal neutron activation analysis, in conjunction with Compton suppression, has been employed to determine arsenic levels in artificially doped urine samples. Typical detection limits were of the order of 10 ng/g. Replicate determinations gave precision values between 2 and 12%, whereas accuracy measurements were between +/- 1 and +/- 20%. Biological and geological reference materials from the National Institute of Standards and Technology (NIST) were also analyzed for arsenic content. Typically, the precision achieved again was between 2 and 12%, whereas the accuracy measurements were in excellent agreement with the certified values.",
Arsenic,2345746,"A 3300-year atmospheric metal contamination record from Raeburn Flow raised bog, south west Scotland Abstract: There is now a plethora of records of atmospheric metal deposition across Europe based on total concentrations and calculated enrichment factors. However, to place such records into an archaeological context and to identify anthropogenic contamination signals more accurately, it is important to separate the signals derived from anthropogenic activities from those of a natural origin. This study presents a new 3300-year record from a bog in the vicinity of Hadrian's Wall and the Northern Pennine orefield in order to generate a new atmospheric metal deposition record for this archaeologically important part of the British Isles. For this purpose multi element geochemistry was undertaken to apportion the contribution of trace metals (lead, zinc, copper, arsenic and mercury) and sulphur as a result of mining/metallurgy and/or geogenic processes. To extract the different contributions through time we used total concentrations and enrichment factors (EF), and applied principal component analysis (PCA) to the dataset. The PCA extracted 7 components: at least two components are necessary to elucidate the trace metal distribution. Zinc, arsenic and lead are mostly related to atmospheric pollution, while mercury and copper appear to be more closely associated with organic matter. Based on these results four phases of lead contamination have been identified that date to: I, c. 2350-1500 cal BP; II, c. 1050-700 cal BP; III, c. 500-350 cal BP and IV, 250 cal BP-present. Copper enrichment also occurs during the Bronze Age (c. 3150-2800 cal BP). Peaks in other metals do not always correspond with lead and they may have been caused by other land use changes or processes that operate internally within the bog. Although the lead can be attributed to both anthropogenic and geogenic sources, its down profile pattern is in accordance with contamination records elsewhere in Britain and Europe, and the lead enrichment recorded at Raeburn Flow suggests that the Northern Pennine orefield was exploited for metals during the late Iron Age and Roman period. (C) 2014 Elsevier Ltd. All rights reserved.",
Arsenic,1251442,"The pag gene product, a physiological inhibitor of c-abl tyrosine kinase, is overexpressed in cells entering S phase and by contact with agents inducing oxidative stress Abstract: The human pag gene product is an inhibitor of the c-abl tyrosine kinase and belongs to a new family of proteins. We show here that higher levels of pag gene expression are observed following induction of proliferation and contact with compounds inducing oxidative stress such as diethyl maleate and sodium arsenate. A weaker overexpression is seen in a macrophage cell line using hydrogen peroxide or menadione as inducers. Pag gene expression increases in synchronized cells entering the S phase. This raises the possibility that elevated levels of pag counteract the cytostatic activity of abl. Treatment of growth arrested cells with diethyl maleate and sodium arsenate induces pag gene overexpression, independently of cell proliferation. Thus, enhanced pag gene expression occurs in two cellular events: proliferation and response to oxidative stress.",
Arsenic,2337219,"Spatial and temporal variability of surface water pollution in the Mekong Delta, Vietnam Abstract: Surface water pollution in the Vietnamese Mekong Delta (MD) could threaten human, animal and ecosystem health given the fact that this water source is intensively used for drinking, irrigation and domestic services. We therefore determined the levels of pollution by organic pollutants, salts, metals and microbial indicators by (bi)monthly monitoring of canals between November 2011 and July 2012 at 32 sampling locations, representing fresh and saline/brackish environments. The results were compared with national water quality guidelines, between the studied regions and with water quality data from main waterways. Key factors explaining the observed levels of pollution in surface water were identified through principal component analysis (PCA). Temporal variations due to tidal regime and seasonality were also assessed. Based on regression models, the spatial variability of five water quality parameters was visualized using GIS based maps. Results indicate that pH (max. 8.6), turbidity (max. 461FTU), maximum concentrations of ammonium (14.7mgL(-1)), arsenic (44.1?gL(-1)), barium (157.5?gL(-1)), chromium (84.7?gL(-1)), mercury (45.5?gL(-1)), manganese (1659.7?gL(-1)), aluminum (14.5mgL(-1)), iron (17.0mgL(-1)) and the number of Escherichia coli (87,000CFU100mL(-1)) and total coliforms (2,500,000CFU100mL(-1)) in canals exceed the thresholds set by Vietnamese quality guidelines for drinking and domestic purposes. The PCA showed that i) urbanization; ii) metal leaching from soils; iii) aquaculture; and iv) tidal regime explain 85% of the variance of surface water quality attributes. Significant differences in water quality were found due to daily tidal regime and as a result of seasonality. Surface water quality maps for dissolved oxygen, ammonium, ortho-phosphate, manganese and total coliforms were developed to highlight hot-spot areas of pollution. The results of this study can assist policy makers in developing water management strategies and drinking water companies in selecting optimum water extraction locations.",
Arsenic,90057,"Mortality and cancer morbidity in workers exposed to sulphur dioxide in a sulphuric acid plant Abstract: To evaluate the risk of non-malignant respiratory disease and tumours at exposure to sulphur dioxide, a retrospective cohort study was performed on a group of 400 male workers, employed for at least six months during the period 1961-1981, in a sulphuric acid factory. Since 1969, fairly extensive measurements have been performed in the respiratory zone of the workers. The median level of total dust, over the years, was 2.2 mg/m3 (time-weighted average), of respirable dust 0.6 mg/m3, of sulphur dioxide 3.6 mg/m3, and of arsenic 11 micrograms/m3. There was a significantly increased total mortality in the period 1961-1985. Applying greater than or equal to 5 years latency period there were 47 observed deaths, giving a standardized mortality rate (SMR) of 1.57 (P = 0.002). The increased mortality was due to violence and intoxication (observed 9, SMR = 2.83; P = 0.006) and cardiovascular disease (SMR = 1.51, P = 0.05). The total tumour morbidity was not increased (observed 17, SMR = 1.17, P greater than 0.5) and there was no rise of either non-malignant or malignant lung diseases. However, there was an increase of bladder cancer (observed 5, SMR = 4.36, P = 0.006).",
Arsenic,1508594,"E-learning in medical education in resource constrained low- and middle-income countries Abstract: BACKGROUND: In the face of severe faculty shortages in resource-constrained countries, medical schools look to e-learning for improved access to medical education. This paper summarizes the literature on e-learning in low- and middle-income countries (LMIC), and presents the spectrum of tools and strategies used. METHODS: Researchers reviewed literature using terms related to e-learning and pre-service education of health professionals in LMIC. Search terms were connected using the Boolean Operators AND and OR to capture all relevant article suggestions. Using standard decision criteria, reviewers narrowed the article suggestions to a final 124 relevant articles. RESULTS: Of the relevant articles found, most referred to e-learning in Brazil (14 articles), India (14), Egypt (10) and South Africa (10). While e-learning has been used by a variety of health workers in LMICs, the majority (58%) reported on physician training, while 24% focused on nursing, pharmacy and dentistry training. Although reasons for investing in e-learning varied, expanded access to education was at the core of e-learning implementation which included providing supplementary tools to support faculty in their teaching, expanding the pool of faculty by connecting to partner and/or community teaching sites, and sharing of digital resources for use by students. E-learning in medical education takes many forms. Blended learning approaches were the most common methodology presented (49 articles) of which computer-assisted learning (CAL) comprised the majority (45 articles). Other approaches included simulations and the use of multimedia software (20 articles), web-based learning (14 articles), and eTutor/eMentor programs (3 articles). Of the 69 articles that evaluated the effectiveness of e-learning tools, 35 studies compared outcomes between e-learning and other approaches, while 34 studies qualitatively analyzed student and faculty attitudes toward e-learning modalities. CONCLUSIONS: E-learning in medical education is a means to an end, rather than the end in itself. Utilizing e-learning can result in greater educational opportunities for students while simultaneously enhancing faculty effectiveness and efficiency. However, this potential of e-learning assumes a certain level of institutional readiness in human and infrastructural resources that is not always present in LMICs. Institutional readiness for e-learning adoption ensures the alignment of new tools to the educational and economic context.",
Arsenic,1255519,"Sodium arsenite-induced abnormalities in expressions of Caveolin-1, eNOS, IKK?, and COX-2 in SV-40 immortalized human uroepithelial cells and in urothelial carcinomas Abstract: Arsenic, a known human carcinogen, is found throughout the crust of the earth. Prolonged arsenic exposure is a known cause of urothelial carcinoma (UC) and blackfoot disease (BFD). The aim of this study was to determine the effect of sodium arsenite on Caveolin-1 and downstream signaling molecules (eNOS, IKK? and COX-2) expression in human urothelial cells (SV-HUC-1). Immunohistochemical (IHC) staining of Caveolin-1, eNOS, IKK?, and COX-2 was also compared between UC patients from endemic and non-endemic areas of BFD in Taiwan. Immunocytochemical staining and Western blotting results revealed increased expression of Caveolin-1, IKK?, and COX-2 but decreased eNOS in SV-HUC-1 cells treated with low concentration of arsenite. Additionally, MEK inhibitor (U0126) significantly attenuated arsenite-induced expression of Caveolin-1, IKK? and COX-2 while reducing eNOS expression. The IHC staining of UCs revealed that expressions of Caveolin-1, IKK?, and COX-2 were significantly higher in patients from endemic areas of BFD compared to patients from non-endemic areas (p=0.011, p=0.002, p=0.0001) whereas eNOS was significantly lower (p=0.0001). The correlation observed between Caveolin-1 and downstream signaling molecule expression may be an important mechanism of arsenic-induced urothelial carcinogenesis.",
Arsenic,627758,"Gender-specific protective effect of hemoglobin on arsenic-induced skin lesions Abstract: Chronic arsenic poisoning remains a public health crisis in Bangladesh. As arsenic has been shown to bind to human hemoglobin (Hb), hematologic mechanisms may play a role in the pathway through which arsenic exerts its toxicity. Two separate studies, a case-control and a cohort, were conducted to investigate the role of Hb in the development of arsenic-induced skin lesions. In the first, conditional logistic regression was used to investigate the effect of Hb on skin lesions among 900 case-control pairs from Pabna, Bangladesh, in which individuals were matched on gender, age, and location. In the second, mixed linear regression models were used to examine the association between toenail arsenic, urinary arsenic, and Hb within a cohort of 184 individuals from 50 families in the same region who did not have arsenic-induced skin lesions. Hb was significantly associated with skin lesions but this association was gender specific. In males, a 40% reduction in the odds of skin lesions occurred for every 1 g/dL increase in Hb (odds ratio, 0.60; 95% confidence interval, 0.49-0.73). No effect was observed for females (odds ratio, 1.16; 95% confidence interval, 0.92-1.46). In the cohort of 184 individuals, no associations between toenail arsenic or urinary arsenic species and Hb levels were observed. Low Hb levels may exacerbate the detrimental health effects of chronic arsenic poisoning. Whereas providing clean water remains the optimal solution to Bangladesh's problem of arsenic poisoning, improving nutrition and reducing iron-deficiency anemia may ameliorate negative health effects, such as skin lesions in individuals who have been exposed.",
Arsenic,1344221,"Heat shock protein (HSP72) and p38 MAPK involvement in sublethal hemorrhage (SLH)-induced tolerance Abstract: <strong>BACKGROUND: </strong>Our in vivo model of tolerance, sublethal hemorrhage (SLH), alters cytokine production, nuclear factor-kappaB mobilization, mitogen-activated protein (MAP) kinase activity, and makes rats tolerant to shock. Heat shock protein (HSP) protects animals from stress. This study investigated if SLH induces in vivo HSP72 expression and whether in vitro HSP72 induction by sodium arsenite (NaArs) alters intracellular signal transduction and cytokine production similar to SLH.<br /><br /><strong>METHODS: </strong>Sprague-Dawley rats were made tolerant by SLH (MAP = 30 mmHg for 15 min, shed blood returned) and given lipopolysaccharide (LPS; 40 mg/kg i.p.) 24 h later. Lung was harvested 1, 12, and 24 h after SLH (n = 4) and 1 h after LPS (n = 8). Other rats underwent bronchoalveolar lavage 24 h after SLH, and macrophages (mphi) were treated with LPS (10 microg/ml). The NR8383 alveolar mphi cell line was treated with 50 microM NaArsx 12 h and LPS. Reverse transcription polymerase chain reaction, Western blots, and enzyme-linked immunosorbent assay were performed for gene, MAPK, and protein expression (tumor necrosis factor [TNF], HSP, p38).<br /><br /><strong>RESULTS: </strong>SLH induced significantly more lung HSP72 mRNA and protein. SLH mphi had more HSP72 protein before and after LPS compared with shams. NaArs induced HSP72 mRNA and protein in NR8383 mphi, and these cells made less TNF compared with controls. NaArs significantly increased p38 activation vs control. SB203580 inhibition of p38 activity did not affect HSP72 expression, or reverse NaArs inhibition of LPS induced TNF production.<br /><br /><strong>CONCLUSION: </strong>SLH induces HSP72 in vivo. In vitro HSP72 induction is associated with increased p38 phosphorylation. Like SLH, mphi with induced HSP72 expression, have an attenuated TNF response. HSP72 acts independently from p38 in inducing tolerance.",
Arsenic,2064164,Mycorrhizal fungi modify element distribution in gametophytes and sporophytes of a fern Pellaea viridis from metaliferous soils Abstract: ,
Arsenic,656853,"Evidence for toxicity differences between inorganic arsenite and thioarsenicals in human bladder cancer cells Abstract: Arsenic toxicity is dependent on its chemical species. In humans, the bladder is one of the primary target organs for arsenic-induced carcinogenicity. However, little is known about the mechanisms underlying arsenic-induced carcinogenicity, and what arsenic species are responsible for this carcinogenicity. The present study aimed at comparing the toxic effect of DMMTA(V) with that of inorganic arsenite (iAs(III)) on cell viability, uptake efficiency and production of reactive oxygen species (ROS) toward human bladder cancer EJ-1 cells. The results were compared with those of a previous study using human epidermoid carcinoma A431 cells. Although iAs(III) was known to be toxic to most cells, here we show that iAs(III) (LC(50)=112 microM) was much less cytotoxic than DMMTA(V) (LC(50)=16.7 microM) in human bladder EJ-1 cells. Interestingly, pentavalent sulfur-containing DMMTA(V) generated a high level of intracellular ROS in EJ-1 cells. However, this was not observed in the cells exposed to trivalent inorganic iAs(III) at their respective LC(50) dose. Furthermore, the presence of N-acetyl-cysteine completely inhibited the cytotoxicity of DMMTA(V) but not iAs(III), suggesting that production of ROS was the main cause of cell death from exposure to DMMTA(V), but not iAs(III). Because the cellular uptake of iAs(III) is mediated by aquaporin proteins, and because the resistance of cells to arsenite can be influenced by lower arsenic uptake due to lower expression of aquaporin proteins (AQP 3, 7 and 9), the expression of several members of the aquaporin family was also examined. In human bladder EJ-1 cells, mRNA/proteins of AQP3, 7 and 9 were not detected by reverse transcription polymerase chain reaction (RT-PCR)/western blotting. In A431 cells, only mRNA and protein of AQP3 were detected. The large difference in toxicity between the two cell lines could be related to their differences in uptake of arsenic species.",
Arsenic,1021559,"Arsenic speciation, distribution, and bioaccessibility in shrews and their food Abstract: Shrews (Sorex cinereus) collected at a historic mine in Nova Scotia, Canada, had approximately twice the arsenic body burden and 100 times greater daily intake of arsenic compared with shrews from a nearby uncontaminated background site. Shrews store arsenic as inorganic and simple methylated arsenicals. Much of the arsenic associated with their primary food source, i.e., small invertebrates, may be soil adsorbed to their exoskeletons. A physiologically based extraction test estimated that 47 ± 2% of invertebrate arsenic is bioaccessible in the shrew gastrointestinal tract. Overall, shrews appear to be efficient at processing and excreting inorganic arsenic.",
Arsenic,1508637,"Comparison between hepatic and renal effects in rats treated with arsenic and/or antioxidants during gestation and lactation Abstract: The aim of this study was to determine whether biochemical changes occurred in the liver and kidney of arsenic (As) exposed pups during gestation and lactation, and investigate the potential beneficial role of antioxidants against arsenic exposure damage. Pregnant wistar rats received the following treatments as drinking water: (1) distilled water; (2) arsenic (50mg/L); (3) antioxidants: zinc (20mg/L)+vitamin C (2g/L)+vitamin E (500mg/L); (4) arsenic (50mg/L)+antioxidants. As- intoxicated pups showed significant decreases in liver cholesterol and triglyceride concentration, whereas Aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities were increased. Treatment with antioxidants returns these values to control ones. TBARS production in both organs and liver glutathione peroxidase (GPx) activity also increased whereas catalase (CAT) activity in both organs decreased in arsenic-exposed pups; the antioxidant administration only recover TBARS concentration to control values. Our findings suggest that administration of antioxidants during gestation and lactation could prevent some of the negative effects of arsenic.",
Arsenic,1579324,"Cell-type specificity of lung cancer associated with low-dose soil heavy metal contamination in Taiwan: An ecological study Abstract: BACKGROUND: Numerous studies have examined the association between heavy metal contamination (including arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], nickel [Ni], lead [Pb], and zinc [Zn]) and lung cancer. However, data from previous studies on pathological cell types are limited, particularly regarding exposure to low-dose soil heavy metal contamination. The purpose of this study was to explore the association between soil heavy metal contamination and lung cancer incidence by specific cell type in Taiwan. METHODS: We conducted an ecological study and calculated the annual averages of eight soil heavy metals (i.e., As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) by using data from the Taiwan Environmental Protection Administration from1982 to 1986. The age-standardized incidence rates of lung cancer according to two major pathological types (adenocarcinoma [AC] and squamous cell carcinoma [SCC]) were obtained from the National Cancer Registry Program conducted in Taiwan from 2001 to 2005. A geographical information system was used to plot the maps of soil heavy metal concentration and lung cancer incidence rates. Poisson regression models were used to obtain the adjusted relative ratios (RR) and 95% confidence intervals (CI) for the lung cancer incidence associated with soil heavy metals. RESULTS: For males, the trend test for lung SCC incidence caused by exposure to Cr, Cu, Hg, Ni, and Zn showed a statistically significant dose--response relationship. However, for lung AC, only Cu and Ni had a significant dose--response relationship. As for females, those achieving a statistically significant dose--response relationship for the trend test were Cr (P = 0.02), Ni (P = 0.02), and Zn (P= 0.02) for lung SCC, and Cu (P < 0.01) and Zn (P = 0.02) for lung AC. CONCLUSION: The current study suggests that a dose--response relationship exists between low-dose soil heavy metal concentration and lung cancer occurrence by specific cell-type; however, the relevant mechanism should be explored further.",
Arsenic,1015662,"Genotoxic potential of arsenic at its reference dose Abstract: Arsenic, a highly hazardous contaminant in our drinking water, accounts for various toxic effects (including cancer) in human. However, intake of arsenic @0.3?gkg(-1)day(-1) through drinking water, containing arsenic at its guideline value or maximum contaminant limit (10?gL(-1)), has been estimated to pose very little or no measurable risk to cancer in humans. The value also appears to be equal to the human reference dose (or index dose) of arsenic based on human skin toxicity data. The present work was a quantitative assessment of the genotoxic potential of arsenic in mice at doses equivalent to its human reference dose as well as its multiples. Significant increases in the frequencies of chromosome abnormalities in the bone marrow cells were registered over the control level upon exposure to all the doses of arsenic including its reference dose (or index dose). The assessment of arsenic genotoxicity in humans at low doses will therefore be highly instrumental in establishing a permissible limit of arsenic in drinking water.",1
Arsenic,1339996,"Long-term arsenic exposure induces histone H3 Lys9 dimethylation without altering DNA methylation in the promoter region of p16(INK4a) and down-regulates its expression in the liver of mice Abstract: Long-term exposure of humans to high concentrations of arsenic is associated with an increased risk of cancer. Previous studies have suggested that arsenic exposure promotes tumorigenesis by inducing changes in the expression of tumor-related genes by dysregulating DNA methylation at tumor-related gene loci. However, the causal relationships between epigenetic changes and both arsenic exposure and tumorigenesis are still unclear. In the present study, we investigated whether arsenic can change the expression of tumor-related genes by inducing epigenetic modifications before tumorigenesis. We did so by investigating the effects of long-term arsenic exposure on representative epigenetic modifications, DNA methylation and histone modifications, in the tumor-free normal liver of C57Bl/6 mice. We focused on the tumor-related genes, p16(INK4a) , RASSF1A, Ha-ras and ER-? as target genes, because their expression and promoter methylation status in mice have been reported to be affected by long-term arsenic exposure. The results showed that long-term arsenic exposure induced a significant decrease in expression of p16(INK4a) associated with an increase in level of dimethylated histone H3 lysine 9 (H3K9), a transcription-suppressive histone modification, in the promoter region, but that DNA methylation of the promoter region was unaffected. The results also showed a significant increase in recruitment of H3K9 histone methyltransferase G9a to the promoter after arsenic exposure. These findings suggest that long-term arsenic exposure may induce down-regulation of p16(INK4a) by targeting recruitment of G9a and H3K9 dimethylation without altering DNA methylation before tumorigenesis in the liver. Copyright © 2012 John Wiley &amp; Sons, Ltd.",
Arsenic,1030949,"The determination of arsine in workplace air by x-ray fluorescence spectrometry Abstract: Arsine (7784421) was collected from air on silver-nitrate impregnated filter papers, and X-ray fluorescence was used for the determination of arsenic content. An assessment was made of the collection efficiency of the filters for laboratory generated arsine. At the three air flow rates used, the collection efficiency was greater than 95 percent, but there was a decrease in collection efficiency with increasing flow rate. Precision was good, with a 5 percent coefficient of variation calculated for levels as low as one tenth of the threshold limit value (TLV) (1 microgram). The method was capable of determining concentrations at 0.1TLV with a sample volume of only 15 liters on a routine basis. Field trials were carried out in a zinc-chloride manufacturing facility in which zinc waste containing arsenic as an impurity was treated with concentrated hydrochloric-acid. Along with hydrogen, appreciable amounts of arsine, hydrogen-sulfide, and hydrochloric-acid mist were evolved. This method of analysis was shown to be in agreement with two other standard methods, and no interference from hydrogen-sulfide was seen. The authors state that this method has the advantages of being safe and nondestructive and can be used for personal exposure monitoring. Use of the X-ray spectrometer allows for rapid analysis of a large number of samples.",
Arsenic,1519157,"Synthesis, characterization and adsorptive properties of carbon with iron nanoparticles and iron carbide for the removal of As(V) from water Abstract: This manuscript presents the synthesis of carbon modified with iron nanoparticles (CFe) and iron carbide (CarFe) from the pyrolyzed crown leaves of pineapple (Ananas comosus) treated with iron salts. The materials that were obtained were used for the removal of As(V) from aqueous media. The carbonaceous materials were characterized by Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS) and Mossbauer Spectroscopy. The specific area (BET), number site density and point of zero charge (pH(pzc)) were also determined. The kinetic parameters were obtained by fitting the experimental data to the pseudo-first-order and pseudo-second-order models. Different isotherm models were applied to describe the As(V) adsorption behavior. The kinetics of As(V) sorption by CFe and CarFe was well defined for the pseudo-second-order model (R(2) = 0.9994 and 0.999, respectively). The maximum As(V) uptake was 1.8 mg g(-1) for CFe and 1.4 mg g(-1) for CarFe. The results obtained indicated that both materials are equally useful for As(V) sorption. The As(V) experimental isotherm data were described by the Freundlich model for CFe and CarFe.",
Arsenic,1327475,"Arsenite-inducible RNA-associated protein (AIRAP) protects cells from arsenite toxicity Abstract: Exposure of cells to arsenicals activates multiple stress pathways resulting in the induction of specific genes whose identity and role in the adaptation to arsenical-induced cellular stress are poorly understood. We report here the identification of a novel gene encoding an arsenite-inducible, cysteine- and histidine-rich RNA-associated protein, AIRAP, that is conserved among mammals, Drosophila and C elegans. Immunochemistry and cell fractionation experiments indicate that, when induced, AIRAP is present in both the nucleus and the cytoplasm, and cross-linking experiments indicate that it associates with RNA in vivo. The expression of a C elegans homologue of AIRAP, aip-1, is also induced by exposure to arsenite, and expression of an aip-1::gfp transgene is most pronounced in hypodermal cells. RNA-mediated interference (RNAi) of aip-1 lowers the resistance of nematodes to arsenite yet does not appear to affect viability under standard growth conditions. These experiments suggest a role for AIRAP/AIP-1 in protecting cells from the toxic effects of arsenite.",
Arsenic,509878,"Morphological and functional alterations in human proximal tubular cell line induced by low level inorganic arsenic: Evidence for targeting of mitochondria and initiated apoptosis Abstract: The kidney is a known target organ for arsenic and is critical for both arsenic biotransformation and elimination. Previous studies have demonstrated that at high doses (ppm) inorganic arsenic is toxic to mitochondria primarily by affecting cellular respiration. However, the effect of inorganic arsenic on mitochondria after low level exposures is not known, particularly in the kidney. Thus the functional and morphological effects of low level inorganic arsenic were investigated in a human proximal tubular cell line, HK-2. Mitochondrial function was assessed at subcytotoxic concentrations of arsenite (<= 10 mu m) by examining the alteration of the mitochondrial membrane potential using MitoTracker Red, a mitochondrion selective dye. In a subset of cells, subcytotoxic arsenite led to mitochondrial membrane depolarization, which could subsequently lead to permeability transition and apoptosis. Subcytotoxic arsenite also induced translocation of phosphatidylserine, indicative of early-stage apoptosis. To confirm whether subcytotoxic arsenite induces cellular and/or mitochondrial morphological alterations consistent with initiated apoptosis, HK-2 cells were evaluated with transmission electron microscopy. Classic morphology of apoptosis was not observed with subcytotoxic arsenite exposures; however, evidence of necrotic changes in the cytoplasmic structure and mitochondrial morphology were apparent. Therefore, based on depolarization of mitochondria and the externalization of phosphatidyllserine, HK-2 cells appear to initiate apoptosis following subcytotoxic arsenite insult, but morphological changes indicate that HK-2 cells fail to complete apoptosis and ultimately undergo necrosis. Therefore, subcytotoxic arsenite can be sufficiently toxic to mitochondria that they lose their ability to keep the cell on course for apoptotic cell death. Copyright (c) 2006 John Wiley & Sons, Ltd.",
Arsenic,2278643,"Preparation, characterization of polyacrylonitrile-aluminum hydroxide composite anion exchanger and its analytical application as AsO4-3 selective membrane electrode Abstract: Polyacrylonitrile–Aluminium hydroxide [PAN–Al(OH)3] composite anion-exchanger was prepared by solid–gel method. The physicochemical properties of the anion exchanger was determined using Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and elemental analysis (CHNS/O) studies. The analytical applications of the anion exchanger have been explored by making View the MathML source selective membrane electrode. Among different composition of membrane the composition of 5:1 (PAN:Al(OH)3) showed best results for water content, porosity, thickness and swelling. These studies showed that the ion selective membrane electrode was selective for View the MathML source having detection limit (1 × 10?7–1 × 10?1 M), response time (40 s) and working pH range (5.0–9.0). The selectivity coefficients values for interfering ions indicate good selectivity for View the MathML source over interfering anions. The results were also compared by PCA-Arsenomat (Arsenic analyzer).",
Arsenic,1508646,"Surface Passivation and Interface Properties of Bulk GaAs and Epitaxial-GaAs/Ge Using Atomic Layer Deposited TiAlO Alloy Dielectric Abstract: High quality surface passivation on bulk-GaAs substrates and epitaxial-GaAs/Ge (epi-GaAs) layers were achieved by using atomic layer deposited (ALD) titanium aluminum oxide (TiAlO) alloy dielectric. The TiAlO alloy dielectric suppresses the formation of defective native oxide on GaAs layers. X-ray photoelectron spectroscopy (XPS) analysis shows interfacial arsenic oxide (As(x)O(y)) and elemental arsenic (As) were completely removed from the GaAs surface. Energy dispersive X-ray diffraction (EDX) analysis and secondary ion mass spectroscopy (SIMS) analysis showed that TiAlO dielectric is an effective barrier layer for reducing the out-diffusion of elemental atoms, enhancing the electrical properties of bulk-GaAs based metal-oxide-semiconductor (MOS) devices. Moreover, ALD TiAlO alloy dielectric on epi-GaAs with AlGaAs buffer layer realized smooth interface between epi-GaAs layers and TiAlO dielectric, yielding a high quality surface passivation on epi-GaAs layers, much sought-after for high-speed transistor applications on a silicon platform. Presence of a thin AlGaAs buffer layer between epi-GaAs and Ge substrates improved interface quality and gate dielectric quality through the reduction of interfacial layer formation (Ga(x)O(y)) and suppression of elemental out-diffusion (Ga and As). The AlGaAs buffer layer and TiAlO dielectric play a key role to suppress the roughening, interfacial layer formation, and impurity diffusion into the dielectric, which in turn largely enhances the electrical property of the epi-GaAs MOS devices.",
Arsenic,1248974,"Geochemistry and health risk assessment of arsenic exposure to street dust in the zinc smelting district, Northeast China Abstract: The aim of this study was to investigate arsenic (As) accumulation in street dust and health risk of population. The investigation concentrated on: a. pollution levels of As in street dust; b. spatial distribution of As in street dust; c. physicochemical properties analysis of street dust; and d. assessment of population health risk due to As exposure to street dust. As concentration in street dust ranged from 3.33 to 185.1 mg kg(-1), with a mean of 33.10 mg kg(-1), which was higher than the background value of Liaoning soil. As contamination level of the area closing to Huludao Zinc Plant (HZP) was highest. Spatial variation showed that the pollution center was close to HZP, formed radial distribution pattern and extended to the northeast and southwest of HZP. The pH and organic matter of street dust were both higher than the background values of soil in Liaoning. There was significantly negative correlation between As concentration and the pH. The mass percentages of particles 180-100, &lt;100-75, &lt;75-63, and &lt;63 ?m were 29.8, 3.7, 21.3, and 4.2 %, respectively. The highest of As concentration was found in the smallest particle size (&lt;63 ?m). As loadings in the particles of grain size 180-100 and &lt;75-63 ?m were higher than other particle fractions. Results of the risk assessment indicated that the highest risk was associated with the ingestion of street dust particles. Health risk for different use scenarios to human decreased in the order of HZP &gt; Industrial district &gt; School &gt; Commercial center &gt; Residential area. Around HZP, Hazard Index (HI) for children and cancer risk of As by street dust exposure exceeded the acceptable values. It indicated that there was a potential adverse effect on children health by As exposure to the street dust of Huludao.",
Arsenic,1372008,"Heat Shock Protein 70 As An Indicator Of Early Lung Injury Caused By Exposure To Arsenic Abstract: Heat shock proteins (HSPs) are a family of highly conserved proteins that are induced by stress, temperature, redox status, heavy metals, and inflammation. HSPs play a major role within a cell from folding of synthesized proteins or its degradation by proteosome. Intracellular transport and defects in folding can cause accumulation of these proteins resulting in several disease processes. HSP expression can be interpreted as an early and sensitive biomarker of cells in stress. Arsenic (As) is a naturally occurring metal that is distributed widely in the environment and is used in several industries. Exposure to As is associated with the development of pulmonary and skin cancers. The present study was undertaken to evaluate the expression levels of Hsp70 protein and mRNA induced by exposure to As which could be a sensitive and early biomarker. In addition, the cellular and molecular mechanisms of Hsp70 expression by As were investigated in the human bronchial cell line BEAS-2B. Cytotoxicity, lipid peroxidation and hydrogen peroxide generation were measured as indicators of cell injury and perturbed oxidative metabolism by As. Exposure of BEAS-2B cells to As(III) was associated with increased expression of Hsp70 protein and mRNA in a time and dose dependent manner. Hsp70 protein expression showed a significant five-fold increase by Western blot analysis and was increased 20-fold using an ELISA assay at a 50 uM As(III) concentration with a 6 hr exposure and an 8 hr recovery time. Hsp70 mRNA expression showed a 28% increase compared to controls. Cytotoxicity resulting from As(III) increased with a longer exposure time (48 hr). Lipid peroxidation increased six-fold at a concentration of 20 uM As(III) for 24 hr exposure, while H2O2 generation showed a twofold increase. These results suggest that the induction of Hsp70 was the most sensitive indicator of cell injury by As(III), and Hsp70 may be a valuable indicator of oxygen free radical-induced lung cell injury.",
Arsenic,628692,"Oxidative stress indices and plasma biochemical parameters during oral exposure to arsenic in rats Abstract: An experiment was conducted to study the response of rat tissues to low level exposure of arsenic (III) for different time periods. Rats were exposed to 0 (Gr. I, healthy control, n=18) or 10 ppm arsenic (Gr. II, positive control, n=18) through drinking water ad lib for a maximum period of 12 weeks. Six rats were sacrificed from each group under light chloroform anesthesia at the end of 4, 8 and 12 weeks of arsenic exposure for collection of blood, liver and kidneys. Samples were processed for estimation of oxidative stress indices and biochemical variables indicative of hepatic and renal functions. Tissue arsenic burden was measured at the end of 12 weeks of exposure. Arsenic treated rats (Gr. II) had comparatively poor body weight gain over time, and the mean body weights of these rats were significantly (P<0.05) lower from 10th weeks onwards. Oral exposure to arsenic for a period of 12 weeks significantly (P<0.05) increased arsenic burden in blood, liver and kidney from arsenic treated rats. This was associated with exposure duration-dependent rise (P<0.05) in lipid peroxidation in these tissues. Superoxide dismutase (SOD) and catalase (CAT) activities increased initially (P<0.05) in all the tissues followed by a declining trend and at the end of 12 weeks, the activities were non-significantly (P>0.05) lower than respective controls. Alterations in most of the biochemical parameters did not reach statistical significance (P>0.05). It was concluded from the present study that low dose arsenic exposure for a shorter period caused activation of intrinsic antioxidant defense whereas a prolonged insult suppressed it. However, biochemical parameters indicative of hepatic and renal dysfunction remained well within the normal range.",
Arsenic,1016708,"Roles of mitogen activated protein kinases and EGF receptor in arsenite-stimulated matrix metalloproteinase-9 production Abstract: The dermatotoxicity of arsenic is well established and epidemiological studies identify an increased incidence of keratinocytic tumors (basal cell and squamous cell carcinoma) associated with arsenic exposure. Little is known about the underlying mechanisms of arsenic-mediated skin carcinogenesis, but activation of mitogen-activated protein (MAP) kinases and subsequent regulation of downstream target genes may contribute to tumor promotion and progression. In this study, we investigated activation of the extracellular signal regulated kinase (ERK) and the stress-associated kinase p38 by arsenite in HaCat cells, a spontaneously immortalized human keratinocyte cell line. Arsenite concentrations &gt; or =100 microM stimulate rapid activation of p38 and ERK MAP kinases. However, upon extended exposure (24 h), persistent stimulation of p38 and ERK MAP kinases was detected at low micromolar concentrations of arsenite. Although ERK and p38 were activated with similar time and concentration dependence, the mechanism of activation differed for these two MAP kinases. ERK activation by arsenite was fully dependent on the catalytic activity of the epidermal growth factor (EGF) receptor and partially dependent on Src-family kinase activity. In contrast, p38 activation was independent of EGF receptor or Src-family kinase activity. Arsenite-stimulated MAP kinase signal transduction resulted in increased production of matrix metalloproteinase (MMP)-9, an AP-1 regulated gene product. MMP-9 induction by arsenite was prevented when EGF receptor or MAP kinase signaling was inhibited. These studies indicate that EGF receptor activation is a component of arsenite-mediated signal transduction and gene expression in keratinocytes and that low micromolar concentrations of arsenite stimulate key signaling pathways upon extended exposure. Stimulation of MAP kinase cascades by arsenic and subsequent regulation of genes including c-fos, c-jun, and the matrix degrading proteases may play an important role in arsenic-induced skin carcinogenesis.",
Arsenic,1579245,"Understanding self-aligned planar growth of InAs nanowires Abstract: Semiconducting nanowires have attracted lots of attentions because of their potential applications. Compared with free-standing nanowires, self-aligned planar nanowires grown epitaxially on the substrate have shown advantageous properties such as being twin defect free and ready for device fabrication, opening potentials for the large scale device applications. Understanding of planar nanowire growth, which is essential for selective growth of planar vs. free standing wires, is still limited. In this paper, we reported different growth behaviors for self-aligned planar and free-standing InAs nanowires under identical growth conditions. We present a new model based on a revised Gibbs-Thomson equation for the planar nanowires. Using this model, we predicted and successfully confirmed through experiments that higher arsenic vapor partial pressure promoted free-standing InAs nanowire growth. A smaller critical diameter for planar nanowire growth was predicted and achieved experimentally. Successful control and understanding of planar and free-standing nanowire growth established in our work opens up the potential of large scale integration of self-aligned nanowires for practical device applications.",
Arsenic,1339393,"Effect of bauxite mineralized soil on residual metal levels in some post harvest food crops in Jamaica Abstract: The concentrations of nine residual metals in some Jamaican foods were determined using inductively coupled plasma mass spectrometry technique. Cadmium concentration was highest in yellow yam (0.21 mg/kg). Sweet potato had the highest concentrations of lead (0.31 mg/kg), arsenic (0.70 mg/kg) and mercury (0.35 mg/kg). Samples from Grove Place exceeded the regulatory limits of 0.1 mg/kg for cadmium, lead and arsenic and 0.05 mg/kg for mercury. Significant correlations were found between soil and agricultural produce concentrations for cadmium and lead (r(2) ? 0.5). These results suggest that the elements were available in soluble forms in the soil for absorption by food crops.",
Arsenic,2343456,"Evaluating the potential for environmental pollution from chromated copper arsenate (CCA)-treated wood waste: A new mass balance approach Abstract: The potential for pollution from arsenic, chromium and copper in chromated copper arsenate (CCA) treated wood waste was assessed using two lysimeter studies. The first utilised lysimeters containing soil and CCA wood waste mulch exposed to natural conditions over a five month period. The second study used the same lysimeter setup in a regulated greenhouse setting with a manual watering regime. Woodchip, soil and leachate samples were evaluated for arsenic, chromium and copper concentrations. Resultant concentration data were used to produce mass balances, an approach thus far unused in such studies. This novel analysis revealed new patterns of mobility and distribution of the elements in the system. The results suggest that CCA wood waste tends to leach on initial exposure to a leachant and during weathering of the wood. When in contact with soil, metal(loid) transport is reduced due to complexation reactions. With higher water application or where the adsorption capacity of the soil is exceeded, the metal(loid)s are transported through the soil column as leachate. Overall, there was an unexplained loss of metal(loid)s from the system that might be attributed to volatilisation of arsenic and plant uptake. This suggests a hitherto unidentified risk to both the environment and human health.",
Arsenic,2088471,"The Role of Chelation in the Treatment of Arsenic and Mercury Poisoning Abstract: Chelation for heavy metal intoxication began more than 70 years ago with the development of British anti-lewisite (BAL; dimercaprol) in wartime Britain as a potential antidote the arsenical warfare agent lewisite (dichloro[2-chlorovinyl]arsine). DMPS (unithiol) and DMSA (succimer), dithiol water-soluble analogs of BAL, were developed in the Soviet Union and China in the late 1950s. These three agents have remained the mainstay of chelation treatment of arsenic and mercury intoxication for more than half a century. Animal experiments and in some instances human data indicate that the dithiol chelators enhance arsenic and mercury excretion. Controlled animal experiments support a therapeutic role for these chelators in the prompt treatment of acute poisoning by arsenic and inorganic mercury salts. Treatment should be initiated as rapidly as possible (within minutes to a few hours), as efficacy declines or disappears as the time interval between metal exposure and onset of chelation increases. DMPS and DMSA, which have a higher therapeutic index than BAL and do not redistribute arsenic or mercury to the brain, offer advantages in clinical practice. Although chelation following chronic exposure to inorganic arsenic and inorganic mercury may accelerate metal excretion and diminish metal burden in some organs, potential therapeutic efficacy in terms of decreased morbidity and mortality is largely unestablished in cases of chronic metal intoxication.",
Arsenic,1677609,"Arsa-diazonium salts with an arsenic-nitrogen triple bond Abstract: Arsenic triply bound: Arsa-diazonium salts containing a cation with an arsenic-nitrogen triple bond ([R-N?As](+) ), which is stable at room temperature, are isolated and fully characterized for the first time. Analogous to the diazonium salts, arsa-diazonium salts can be used in [3+2] dipolar cycloaddition reactions with azides to prepare arsenic analogues (RAsN4 ) of pentazoles (RN5 ).",
Arsenic,627045,"Disruption of the arsenic (+3 oxidation state) methyltransferase gene in the mouse alters the phenotype for methylation of arsenic and affects distribution and retention of orally administered arsenate Abstract: The arsenic (+3 oxidation state) methyltransferase (As3mt) gene encodes a 43 kDa protein that catalyzes methylation of inorganic arsenic. Altered expression of AS3MT in cultured human cells controls arsenic methylation phenotypes, suggesting a critical role in arsenic metabolism. Because methylated arsenicals mediate some toxic or carcinogenic effects linked to inorganic arsenic exposure, studies of the fate and effects of arsenicals in mice which cannot methylate arsenic could be instructive. This study compared retention and distribution of arsenic in As3mt knockout mice and in wild-type C57BL/6 mice in which expression of the As3mt gene is normal. Male and female mice of either genotype received an oral dose of 0.5 mg of arsenic as arsenate per kg containing [(73)As]-arsenate. Mice were radioassayed for up to 96 h after dosing; tissues were collected at 2 and 24 h after dosing. At 2 and 24 h after dosing, livers of As3mt knockouts contained a greater proportion of inorganic and monomethylated arsenic than did livers of C57BL/6 mice. A similar predominance of inorganic and monomethylated arsenic was found in the urine of As3mt knockouts. At 24 h after dosing, As3mt knockouts retained significantly higher percentages of arsenic dose in liver, kidneys, urinary bladder, lungs, heart, and carcass than did C57BL/6 mice. Whole body clearance of [(73)As] in As3mt knockouts was substantially slower than in C57BL/6 mice. At 24 h after dosing, As3mt knockouts retained about 50% and C57BL/6 mice about 6% of the dose. After 96 h, As3mt knockouts retained about 20% and C57BL/6 mice retained less than 2% of the dose. These data confirm a central role for As3mt in the metabolism of inorganic arsenic and indicate that phenotypes for arsenic retention and distribution are markedly affected by the null genotype for arsenic methylation, indicating a close linkage between the metabolism and retention of arsenicals.",
Arsenic,627506,"Inhibition of alpha7-nicotinic acetylcholine receptor expression by arsenite in the vascular endothelial cells Abstract: The ?7-nicotinic acetylcholine receptor (?7-nAChR), expressed in the neuronal and non-neuronal cells, has been shown to regulate cell proliferation. However, the expression and function of the ?7-nAChR in the proliferation of the vascular endothelial cells remain unclear. In this study, we investigated the expression of the ?7-nAChR in the arsenite-exposed vascular endothelial cells. The vascular endothelial cells SVEC4-10 and porcine aorta endothelial cells (PAEC) expressed the ?7-nAChR proteins. Moreover, the location of the ?7-nAChR proteins on cell membrane of the vascular endothelial cells was identified by the ?7-nAChR binding to a tetramethylrhodamine-labeled ?-bungarotoxin (?-BTX). Arsenite (20 ?M, 24 h) significantly induced the cytotoxicity, cell growth inhibition, and apoptosis in the vascular endothelial cells. The level of ?7-nAChR proteins was concentration dependently decreased in the arsenite-treated endothelial cells. Furthermore, a specific ?7-nAChR antagonist, ?-BTX, inhibited the cell viability in the vascular endothelial cells. Nevertheless, ?-BTX, and a ?7-nAChR agonist, nicotine, did not significantly alter the cytotoxicity in the arsenite-treated endothelial cells. In addition, arsenite decreased the level of endothelial nitric oxide synthase proteins but did not alter choline acetyltransferase proteins in the SVEC4-10 endothelial cells. Together, our results indicate that arsenite can inhibit the ?7-nAChR protein expression and cause the cell injury in the vascular endothelial cells.",
Arsenic,2088461,"Pro-inflammatory effects and oxidative stress in lung macrophages and epithelial cells induced by ambient particulate matter Abstract: The objective of this study was to compare the toxicological effects of different source-related ambient PM10 samples in regard to their chemical composition. In this context we investigated airborne PM from different sites in Aachen, Germany. For the toxicological investigation human alveolar epithelial cells (A549) and murine macrophages (RAW264.7) were exposed from 0 to 96 h to increasing PM concentrations (0-100 ?g/ml) followed by analyses of cell viability, pro-inflammatory and oxidative stress responses. The chemical analysis of these particles indicated the presence of 21 elements, water-soluble ions and PAHs. The toxicological investigations of the PM10 samples demonstrated a concentration- and time-dependent decrease in cell viability and an increase in pro-inflammatory and oxidative stress markers.",
Arsenic,2064302,"Consumption of Ruditapes philippinarum and Ruditapes decussatus: comparison of element accumulation and health risk Abstract: Ruditapes philippinarum, a species native from the Indo-Pacific region, was introduced in Europe at the beginning of the 1970s for culture purposes, leading to a massive decrease of the native species Ruditapes decussatus and a high increase of R. philippinarum yields in Europe. Bivalves can accumulate high amounts of metals and thus easily reach concentrations that are toxic not only to themselves but also to consumers. Since differences in the accumulation of pollutants may exist between bivalve species, different health risks may be overcome. For this reason, the level of metals in seafood raises public health concerns, and international organisations like European Food Safety Authority, United States Food and Drug Administration, and Food Standards Australia and New Zealand (FSANZ) set maximum levels (MLs), above which edible seafood cannot be marketed. In order to evaluate the risk associated with the consumption of R. philippinarum and R. decussatus, both clam species were collected in the same site in Ria de Aveiro and the concentration of eight elements determined in organisms before and after a 48-h depuration period. Results evidence that even at low contaminated areas, the MLs for some elements can easily be achieved. The concentrations of As were above the reference values for FSANZ, and the provisional tolerable weekly intake (PTWI) is exceeded for As when more than 0.5 kg of R. decussatus and 0.9 kg of R. philippinarum clam flesh is consumed, in 1 week, by an adult (70 kg). When comparing with other systems worldwide, consumers of depurated clams from this coastal system have a similar or lower risk of exceeding the PTWI for Cd, As, Pb, and Hg. The recently introduced clam, R. philippinarum, accumulates lower amounts of the most health-threatening elements (less than 71 % of Cd, 40 % of As, and 20 % of Hg) than the native R. decussatus, except for Pb. R. philippinarum also reduces more the element burden when subjected to depuration than R. decussatus. Moreover, R. philippinarum allocates a lower proportion of the accumulated elements in the soluble fraction, where they are readily available. Thus, it is safer to consume R. philippinarum than R. decussatus, except when clams come from areas heavily polluted by Pb.",
Arsenic,1018261,"Arsenic speciation in clinical samples: Urine analysis using fast micro-liquid chromatography ICP-MS Abstract: Arsenic speciation is a subject that is developing all the time both from improvements in analytical techniques and from increases in toxicological understanding. Despite speciation methods being widely developed, arsenic speciation is not routinely offered as an analysis in clinical laboratory. The work in this paper describes a simple routine method for arsenic speciation that could be easily implemented in clinical laboratories. The method described, a new, fast analytical method for arsenic speciation, is reported using micro-liquid chromatography hyphenated to an inductively coupled plasma mass spectrometer (?LC-ICP-MS). The method uses a low-pressure delivery six-port valve with a 5 cm anion exchange column, which allows a fully resolved separation of five arsenic species (arsenobetaine [AB], arsenite [As(3+)], arsenate [As(5+)], mono-methylarsonic acid [MMA(5+)] and dimethylarsinic acid [DMA(5+)]) in urine in just 6 min. This fast analytical method offers an arsenic speciation method that is feasible for a laboratory that does not have the capability for a dedicated arsenic speciation LC-ICP-MS instrument. The micro-LC system is small, easy to install and is fully integrated with the ICP-MS software. The results reported here are from urine samples from 65 workers in a semiconductor work providing a sample for their routine biological monitoring to assess workplace exposure. Control samples from 20 unexposed people were also determined. Results show that the semiconductor workers exhibit very low levels of arsenic in their urine samples, similar to the levels in the controls, and thus are not significantly exposed to arsenic. Care must be taken when interpreting urinary arsenic species results because it is not always possible to differentiate between dietary and other external sources of exposure.",
Arsenic,1337270,"Environmental arsenic exposure and serum matrix metalloproteinase-9 Abstract: The objective of this study was to evaluate the relationship between environmental arsenic exposure and serum matrix metalloproteinase (MMP)-9, a biomarker associated with cardiovascular disease and cancer. In a cross-sectional study of residents of Arizona, USA (n=215) and Sonora, Mexico (n=163), drinking water was assayed for total arsenic, and daily drinking water arsenic intake was estimated. Urine was speciated for arsenic, and concentrations were adjusted for specific gravity. Serum was analyzed for MMP-9 using ELISA. Mixed model linear regression was used to assess the relation among drinking water arsenic concentration, drinking water arsenic intake, urinary arsenic sum of species (the sum of arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid), and MMP-9, controlling for autocorrelation within households. Drinking water arsenic concentration and intake were positively associated with MMP-9, both in crude analysis and after adjustment for gender, country/ethnicity, age, body mass index, current smoking, and diabetes. Urinary arsenic sum of species was positively associated with MMP-9 in multivariable analysis only. Using Akaike's Information Criterion, arsenic concentration in drinking water provided a better fitting model of MMP-9 than either urinary arsenic or drinking water arsenic intake. In conclusion, arsenic exposure evaluated using all three exposure metrics was positively associated with MMP-9.Journal of Exposure Science and Environmental Epidemiology advance online publication, 12 December 2012; doi:10.1038/jes.2012.107.",
Arsenic,627318,"Blood arsenic as a biomarker of arsenic exposure: Results from a prospective study Abstract: Exposure to arsenic (As)-contaminated drinking water affects millions of people worldwide. Arsenic exposure is associated with skin lesions, skin, lung, kidney and liver cancers, neurologic and cardiovascular effects. Past studies involving biomarkers of As exposure have typically examined urinary As (UAs) (adjusted for urinary creatinine), hair or toenail As, but not blood As (BAs) since blood concentrations are exceedingly low and are not detectable by conventional atomic absorption spectrophotometric techniques. In a case-cohort analysis of 303 newly diagnosed cases of skin lesions, and 849 subcohort members randomly selected from 8092 participants in the health effects of as longitudinal study (HEALS) in Araihazar, Bangladesh, we measured blood, urine and water As concentrations, and examined their associations with each other, and with the risk for skin lesions. BAs concentrations were highly correlated with creatinine-adjusted UAs concentrations (r=0.85) and with water As (WAs) (r=0.75). We observed consistent dose-response relationships between the risk of skin lesions and all the measures of As exposure. Rate ratios (RRs) for skin lesions by quintile of As exposure, adjusted for age and gender, revealed that the two highest quintiles were significantly related to an increased risk of skin lesions for each measure of exposure: BAs, UAs, WAs and a time-weighted water As variable. This prospective study confirms the increased risk of skin lesions in relation to As concentrations in blood, urine and water and also establishes that BAs is a useful biomarker of As exposure in this study population.",
Arsenic,1519137,"Response of wheat cultivars to arsenic contamination in polluted soils of West Bengal, India Abstract: Arsenic, the toxic metalloid, widely available in the natural ecosystem, poses serious problem through contaminated groundwater and drinking water. The emerging areas of arsenic hazards in agricultural systems through use of contaminated irrigation water and entry of toxin in crops has been largely overlooked. Arsenic accumulation by plants and its translocation to edible parts were observed to vary within crops and also across the cultivars. Wheat is an alternative choice of summer rice, due to low water requirement. With this background, the current experiment was conducted with four popular wheat cultivars to study the arsenic accumulation and varietal tolerance under different soils and groundwater. The arsenic content was determined by using atomic absorption spectrophotometer (AAS). Result revealed that, wheat cultivars differed in their grain arsenic concentration (0.23–1.22 mg kg?1), which differed across the sites and year of experiment. The arsenic translocation in wheat grains usually least, and accumulation by different tissues followed the order root > stem > leaf > grain across the cultivars. The cultivar UP-262 was found to accumulate least arsenic in grains and cultivar Kalyansona the highest under same growing condition, due to phyto-extraction or phyto-morphological potential of the varieties.",
Arsenic,1677550,"Attic dust assessment near a wood treatment plant: Past air pollution and potential exposure Abstract: The wood treatment process uses substances that generate hazardous compounds that may contaminate environmental compartments. In the present study, an area under influence of a deactivated wood treatment plant was investigated to evaluate past air pollution and to try to understand local air dispersion. Attic dust samples were collected from eight residences around the plant and from two residences outside this area, as reference samples. The presence of copper, chromium, arsenic, pentachlorophenol, sixteen priority polycyclic aromatic hydrocarbons and mutagenic activity using Salmonella/microsome assay was evaluated. The residences close to the entrance to the plant were the most affected, according to potentially toxic elements analysis. The PCP concentration was 0.49mg/kg and the total PAHs content ranged from 0.40 to 13.31?g/g with greater dispersion than potentially toxic elements. The highest mutagenesis values were 15,905 and 10,399 revertants/g of dust in the absence and presence of S9 mix (mammalian metabolic activation), respectively. Samples in which the total PAHs concentration was less than 2?g/g no mutagenic effects were observed, including the residences in the reference area. The contribution of PAHs to mutagenesis was 10 percent, indicating that other compounds may contribute to the mutagenic effect. These results suggest that the population was or is potentially exposed to substances with strong effects on health.",
Arsenic,2064242,"Bioaccumulation and the soil factors affecting the uptake of arsenic in earthworm, Eisenia fetida Abstract: To better understand arsenic (As) bioaccumulation, a soil invertebrate species was exposed to 17 field soils contaminated with arsenic due to mining activity. Earthworms (Eisenia fetida) were kept in the soils for 70 days under laboratory conditions, as body burden increased and failed to reach equilibrium in all soils. After 70 days of exposure, XANES spectra determined that As was biotransformed to a highly reduced form. Uptake kinetics for As was calculated using one compartment model. Stepwise multiple regression suggested that sorbed As in soils are bioaccessible, and uptake is governed by soil properties (iron oxide, sulfate, and dissolved organic carbon) that control As mobility in soils. As in soil solution are highly related to uptake rate except four soils which had relatively high chloride or phosphate. The results imply that uptake of As is through As interaction with soil characteristics as well as direct from the soil solution. Internal validation showed that empirically derived regression equations can be used for predicting As uptake as a function of soil properties within the range of soil properties in the data set.",
Arsenic,627786,"Arsenic concentrations in prediagnostic toenails and the risk of bladder cancer in a cohort study of male smokers Abstract: At high concentrations, inorganic arsenic can cause bladder cancer in humans. However, it is unclear whether low exposure to inorganic arsenic in drinking water (<100 µg/liter) is related to bladder cancer risk. No study has been known to use biomarkers to assess the relation between individual arsenic exposure and bladder cancer risk. Toenail samples provide an integrated measure of internal arsenic exposure and reflect long-term exposure. The authors examined the relation between toenail arsenic levels and bladder cancer risk among participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a cohort of Finnish male smokers aged 50–69 years. Data for 280 incident bladder cancer cases, identified between baseline (1985–1988) and April 1999, were available for analysis. One control was matched to each case on the basis of age, toenail collection date, intervention group, and smoking duration. Arsenic levels in toenail samples were determined by using neutron activation analysis. Logistic regression analyses were performed to estimate odds ratios. Arsenic toenail concentrations in this Finnish study were similar to those reported in US studies (range: 0.02–17.5 µg/g). The authors observed no association between inorganic arsenic concentration and bladder cancer risk (odds ratio = 1.13, 95% confidence interval: 0.70, 1.81 for the highest vs. lowest quartile). These findings suggest that low-level arsenic exposure is unlikely to explain a substantial excess risk of bladder cancer.",
Arsenic,628489,"Activation of Nrf2 by arsenite and monomethylarsonous acid is independent of Keap1-C151: Enhanced Keap1-Cul3 interaction Abstract: Drinking water contaminated with arsenic, a human carcinogen, is a worldwide health issue. An understanding of cellular signaling events in response to arsenic exposure and rational designing of strategies to reduce arsenic damages by modulating signaling events are important to fight against arsenic-induced diseases. Previously, we reported that activation of the Nrf2-mediated cellular defense pathway confers protection against toxic effects induced by sodium arsenite [As(III)] or monomethylarsonous acid [MMA(III)]. Paradoxically, arsenic has been reported to induce the Nrf2-dependent signaling pathway. Here, we report the unique mechanism of Nrf2 induction by arsenic. Similar to tert-butylhydroquinone (tBHQ) or sulforaphane (SF), arsenic induced the Nrf2-dependent response through enhancing Nrf2 protein levels by inhibiting Nrf2 ubiquitination and degradation. However, the detailed action of arsenic in Nrf2 induction is different from that of tBHQ or SF. Arsenic markedly enhanced the interaction between Keap1 and Cul3, subunits of the E3 ubiquitin ligase for Nrf2, which led to impaired dynamic assembly/disassembly of the E3 ubiquitin ligase and thus decreased its ligase activity. Furthermore, induction of Nrf2 by arsenic is independent of the previously identified C151 residue in Keap1 that is required for Nrf2 activation by tBHQ or SF. Distinct mechanisms of Nrf2 activation by seemingly harmful and beneficial reagents provide a molecular basis to design Nrf2-activating agents for therapeutic intervention.",
Arsenic,1247279,"ATF4-dependent oxidative induction of the DNA repair enzyme Ape1 counteracts arsenite cytotoxicity and suppresses arsenite-mediated mutagenesis Abstract: Arsenite is a human carcinogen causing skin, bladder, and lung tumors, but the cellular mechanisms underlying these effects remain unclear. We investigated expression of the essential base excision DNA repair enzyme apurinic endonuclease 1 (Ape1) in response to sodium arsenite. In mouse 10T(1/2) fibroblasts, Ape1 induction in response to arsenite occurred about equally at the mRNA, protein, and enzyme activity levels. Analysis of the APE1 promoter region revealed an AP-1/CREB binding site essential for arsenite-induced transcriptional activation in both mouse and human cells. Electrophoretic mobility shift assays indicated that an ATF4/c-Jun heterodimer was the responsible transcription factor. RNA interference targeting c-Jun or ATF4 eliminated arsenite-induced APE1 transcription. Suppression of Ape1 or ATF4 sensitized both mouse fibroblasts (10T(1/2)) and human lymphoblastoid cells (TK6) to arsenite cytotoxicity. Expression of Ape1 from a transgene did not efficiently restore arsenite resistance in ATF4-depleted cells but did offset initial accumulation of abasic DNA damage following arsenite treatment. Mutagenesis by arsenite (at the TK and HPRT loci in TK6 cells) was observed only for ATF4-depleted cells, which was strongly offset by Ape1 expression from a transgene. Therefore, the ATF4-mediated up-regulation of Ape1 and other genes plays a key role against arsenite-mediated toxicity and mutagenesis.",
Arsenic,1029567,"Expression of AS3MT alters transcriptional profiles in human urothelial cells exposed to arsenite Abstract: Inorganic arsenic (iAs) is an environmental toxicant and human carcinogen. The enzymatic methylation of iAs that is catalyzed by arsenic (+3 oxidation state)-methyltransferase (AS3MT) generates reactive methylated intermediates that contribute to the toxic and carcinogenic effects of iAs. We have shown that clonal human urothelial cells (UROtsa/F35) that express rat AS3MT and methylate iAs are more susceptible to acute toxicity of arsenite (iAs(III)) than parental UROtsa cells that do not express AS3MT and do not methylate iAs. The current work examines transcriptional changes associated with AS3MT expression and identifies specific categories of genes expressed in UROtsa and UROtsa/F35 cells in response to a 24-h exposure to 1 or 50 microM iAs(III). Here, the expression of 21,073 genes was assessed using Agilent Human 1A(V2) arrays. Venn analysis showed marked concentration-dependent differences between gene expression patterns in UROtsa and UROTsa/F35 cells exposed to iAs(III). Among 134 genes altered by exposure to subtoxic 1 microM iAs(III), only 14 were shared by both cell lines. Exposure to cytotoxic 50 microM iAs(III) uniquely altered 1389 genes in UROtsa/F35 and 649 genes in UROtsa cells; 5033 altered genes were associated with the chemical alone. In UROtsa, but not UROtsa/F35 cells exposure to 1 microM iAs(III) altered expression of genes associated with cell adhesion. In contrast, expression of genes involved in cell cycle regulation was significantly altered in UROtsa/F35 cells at this exposure level. At 50 microM iAs(III), pathways regulating cell cycle, cell death, transcription, and metabolism were affected in both cell lines. However, only Urotsa/F35 cells showed numerous G-protein and kinase pathway alterations as well as alterations in pathways involved in cell growth and differentiation. These data link the AS3MT-catalyzed methylation of iAs to specific genomic responses in human cells exposed to iAs(III). Further analysis of these responses will help to characterize the role of AS3MT-catalyzed methylation in modulation of iAs(III) toxicity.",
Arsenic,1380126,ARSENIC UNCOUPLES CARDIAC AND RESPIRATORY RESPONSES OF HEMIFUSUS-TUBA GMELIN TO THERMAL STRESS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXICITY BIOACCUMULATION OXYGEN CONSUMPTION,
Arsenic,1017889,"Ecosystem perspective of groundwater arsenic contamination in India and relevance in policy Abstract: Millions of people living in India are at risk by consuming arsenic contaminated groundwater. Several technological solutions have failed to address the problem due to segmental approaches, resulting in human suffering for a period of three decades. The article is based on an analysis of arsenic-related health problems from an ecosystem perspective through a primary survey conducted in five arsenic affected villages in the state of West Bengal and review of existing research and policy documents. Although modern agricultural practices and drinking water policies have resulted in arsenic contamination of groundwater, current mitigation policy is essentially confined to biomedical approaches, which includes potable water supply and medical care. The study also shows that existing disparity, difficulty in coping, inaccessibility to health service and potable water supply and lack of participation in decision making have resulted in more suffering among the poor. On the other hand, spreading of arsenic contamination in the ecosystem remains unabated. Foods grown in the affected area have emerged as additional sources of exposure to humans. There is lack of evidence of any perceivable benefits due to sustainable agriculture, as present nature of agriculture practice is essentially driven by crop yield only. Further research is needed to generate credible evidence of alternative agriculture paradigms that may eventually reduce body burden of arsenic through reduced dependency on groundwater.",
Arsenic,1339973,"Arsenic stress elicits cytosolic Ca(2+) bursts and Crz1 activation in Saccharomyces cerevisiae Abstract: Although arsenic is notoriously poisonous to life, its utilization in therapeutics brings many benefits to human health, so it is therefore essential to discover the molecular mechanisms underlying arsenic stress responses in eukaryotic cells. Aiming to determine the contribution of Ca(2+) signalling pathways to arsenic stress responses, we took advantage of the use of Saccharomyces cerevisiae as a model organism. Here we show that Ca(2+) enhances the tolerance of the wild-type and arsenic-sensitive yap1 strains to arsenic stress in a Crz1-dependent manner, thus providing the first evidence that Ca(2+) signalling cascades are involved in arsenic stress responses. Moreover, our results indicate that arsenic shock elicits a cytosolic Ca(2+) burst in these strains, without the addition of exogenous Ca(2+) sources, strongly supporting the notion that Ca(2+) homeostasis is disrupted by arsenic stress. In response to an arsenite-induced increase of Ca(2+) in the cytosol, Crz1 is dephosphorylated and translocated to the nucleus, and stimulates CDRE-driven expression of the lacZ reporter gene in a Cnb1-dependent manner. The activation of Crz1 by arsenite culminates in the induction of the endogenous genes PMR1, PMC1 and GSC2. Taken together, these data establish that activation of Ca(2+) signalling pathways and the downstream activation of the Crz1 transcription factor contribute to arsenic tolerance in the eukaryotic model organism S. cerevisiae.",
Arsenic,1032401,"Suppression of splenic accessory cell function in mice exposed to gallium arsenide Abstract: Acute exposure of mice to a single intratracheal dose of gallium arsenide (50, 100, and 200 mg/kg) depresses the primary IgM antibody response to the T-dependent antigen sheep red blood cells (SRBC) through alterations in the function of splenic accessory cells. To determine the mechanism by which GaAs exposure influences splenic accessory cells, the cells were isolated by adherence and their functional capability investigated 24 hr following GaAs exposure in the animal. Splenic adherent cells from GaAs-exposed mice were greatly impaired in their ability to process and present the particulate antigen SRBC to a SRBC-primed T-cell population. However, GaAs exposure did not inhibit phagocytosis of fluorescent covaspheres by these cells, nor did it inhibit in vivo phagocytosis of 51Cr-labeled SRBC, indicating that the findings reported here were not due to decreased uptake of antigen by the accessory cells. Furthermore, production of IL-1 by these cells from exposed mice was not different from control and addition of exogenous IL-1 to cultures did not reverse GaAs-induced inhibition of the primary antibody response. GaAs exposure did not affect the percentage of Ia positive macrophages (F4/80 positive cells), but the amount of cell surface IAk molecules expressed was significantly decreased as measured by flow cytometry. In contrast to the SRBC response, GaAs did not suppress the ability of adherent splenocytes to process and present the antigen pigeon cytochrome c to the helper/inducer T cell clone F1.A.2 or the antigen KLH (keyhole limpet hemocyanin) to KLH-primed T cells. Therefore, GaAs exposure interferes with the capacity of splenic macrophages to process and/or present the particulate antigen SRBC, but not the soluble protein antigens pigeon cytochrome c or KLH.",
Arsenic,2088480,"Chelator-free synthesis of a dual-modality PET/MRI agent Abstract: Old technique, new application: A simple and efficient chelator-free strategy for the synthesis of a novel dual-modality PET/MRI agent has been developed. Labeling of radioarsenic (*As(III) and *As(V) , *=71, 72, 74, 76) at the surface of superparamagnetic iron oxide nanoparticles (SPIONs) resulted in *As-SPIONs that can be used for simultaneous PET/MRI in cancer diagnosis, lymph-node mapping, and potentially for internal radiotherapy.",
Arsenic,628039,"Modulation of DNA repair and glutathione levels in human keratinocytes by micromolar arsenite Abstract: Arsenic (As) is a human carcinogen, but not a mutagen, although it inhibits DNA repair and is a comutagen. Human AG06 keratinocytes treated with micromolar arsenic exhibit dose and time dependent loss of DNA ligase function. However, purified human DNA ligase I, ligase III, and other repair enzymes such as DNA polymerase ?,are not inhibited by less than millimolar arsenite, As(lII), the most toxic form of As found in the environment. DNA ligase activity in extracts from untreated keratinocytes is also insensitive to less than millimolar As. Pyruvate dehydrogenase, on the other hand, is inhibited by micromolar As and probably determines As-induced cytotoxicity. Simultaneous treatment of AG06 cells with an alkylating agent, I-methyl-3-nitro-l-nitrosoguanidine '(MNNG), plus As produces a synergistic increase in viability (dye uptake) at low doses and a synergistic increase in toxicity at high doses. Micromolar As also modulates cellular redox levels and induces a variety of cellular stress response genes. Keratinocytes treated with As exhibit both a time and dose-dependent increase in cellular GSH levels and alterations in the relative activity of several GSH-dependent enzymes. These As-induced changes in cellular redox capacity and DNA repair activity are not directly related to toxicity. Maximal induction of GSH and DNA repair occurs after treatment with sub-toxic concentrations of As. At submicromolar concentrations, arsenic also induces hyperproliferation of keratinocytes, both in vivo and in vitro. Our results suggest that As modulates DNA repair and redox levels primarily through post-translational or transcriptional mechanisms.",
Arsenic,1337523,"Bladder/lung cancer mortality in Blackfoot-disease (BFD)-endemic area villages with low (<150?g/L) well water arsenic levels - An exploration of the dose-response Poisson analysis Abstract: OBJECTIVE: To examine the analytic role of arsenic exposure on cancer mortality among the low-dose (well water arsenic level &lt;150?g/L) villages in the Blackfoot-disease (BFD) endemic area of southwest Taiwan and with respect to the southwest regional data. METHOD: Poisson analyses of the bladder and lung cancer deaths with respect to arsenic exposure (?g/kg/day) for the low-dose (&lt;150?g/L) villages with exposure defined by the village median, mean, or maximum and with or without regional data. RESULTS: Use of the village median well water arsenic level as the exposure metric introduced misclassification bias by including villages with levels &gt;500?g/L, but use of the village mean or the maximum did not. Poisson analyses using mean or maximum arsenic levels showed significant negative cancer slope factors for models of bladder cancers and of bladder and lung cancers combined. Inclusion of the southwest Taiwan regional data did not change the findings when the model contained an explanatory variable for non-arsenic differences. A positive slope could only be generated by including the comparison population as a separate data point with the assumption of zero arsenic exposure from drinking water and eliminating the variable for non-arsenic risk factors. CONCLUSION: The cancer rates are higher among the low-dose (&lt;150?g/L) villages in the BFD area than in the southwest Taiwan region. However, among the low-dose villages in the BFD area, cancer risks suggest a negative association with well water arsenic levels. Positive differences from regional data seem attributable to non-arsenic ecological factors.",
Arsenic,2216501,"As, Cd, Cr, Pb and Hg in seafood species used for sashimi and evaluation of dietary exposure Abstract: The presence of inorganic contaminants As, Cd, Cr, Hg and Pb was evaluated in 116 samples of muscles of seafood used for sashimi from Japanese restaurants in Campinas, SP, Brazil. Tuna (Thunnus thynnus), salmon (Salmo solar), mullet (Mugil platanus) and octopus (Octopus vulgaris) were the most common seafood species in these restaurants. Samples were digested in a microwave assisted system and the contaminants were determined by inductively coupled plasma (ICP OES). The percentage of samples above the maximum limit permitted by MERCOSUL and European regulations were: As (90% tuna, 48% salmon, 31% mullet and 100% octopus); Cd (61% octopus); Hg (7% tuna); Pb (6% mullet). Octopus and tuna were the sashimi that most contributed to arsenic and mercury intake, respectively.",
Arsenic,1508632,"Identification and analysis of a novel dimerization domain shared by various members of c-Jun N-terminal kinase (JNK) scaffold proteins Abstract: Mitogen-activated protein kinases (MAPKs) form a kinase tier module in which MAPK, MAP2K and MAP3K are held by scaffold proteins. The scaffold proteins serve as a protein platform for selective and spatial kinase activation. The precise mechanism by which the scaffold proteins function has not yet been fully explained. WDR62 is a novel scaffold protein of the c-Jun N-terminal kinase (JNK) pathway. Recessive mutations within WDR62 result in severe cerebral cortical malformations. One of the WDR62 mutant proteins found in a patient with microcephaly encodes a C-terminal truncated protein that fails to efficiently associate with JNK and MKK7?1. The present paper shows that the WDR62 C-terminal region harbors a novel dimerization domain composed of a putative loop-helix domain that is necessary and sufficient for WDR62 dimerization and is critical for its scaffolding function. The loop-helix domain is highly conserved between orthologues and is also shared by the JNK scaffold protein, JNKBP1/MAPKBP1. Based on the high sequence conservation of the loop-helix domain, our paper shows that MAPKBP1 homodimerizes and heterodimerizes with WDR62. Endogenous WDR62 and MAPKBP1 co-localize to stress granules following arsenite treatment, but not during mitosis. This study proposes another layer of complexity, in which coordinated activation of signaling pathways is mediated by the association between the different JNK scaffold proteins depending on their biological function.",
Arsenic,1026364,"Mechanism of metalloid-induced death in Leishmania spp.: role of iron, reactive oxygen species, Ca2+, and glutathione Abstract: There is growing evidence that metalloid-induced cell death in protozoan parasites is due to oxidative injury; however, the biochemical changes related to this event are not fully understood. Leishmania spp. demonstrated cross-resistance to two related metalloids, arsenic and antimony, and both metalloids induced cell death accompanied by cell shrinkage and DNA fragmentation that was preceded by an increase in reactive oxygen species. Both drugs caused mitochondrial dysfunction in terms of loss of membrane potential and a drop in ATP levels. Arsenic treatment resulted in an elevation of intracellular Ca2+ levels that did not occur with antimony exposure. Cellular glutathione level was reduced after antimony treatment but arsenic did not affect glutathione. Inhibition of Ca2+ influx during arsenic treatment reduced cell death, whereas supplementation of glutathione during antimony treatment rescued cell loss. Under iron-depleted conditions, the cytotoxic effects of arsenic and antimony did not occur and cell survival increased; in contrast, the presence of excess iron resulted in higher cell death. Therefore, this study provides a new possibility that iron can potentiate parasite death induced by metalloids like arsenic and antimony. In addition, an important observation is that the two similar metalloids produce toxicity by very different mechanisms.",
Arsenic,1255514,"Arsenic contamination of coarse-grained and nanostructured nitinol surfaces induced by chemical treatment in hydrofluoric acid Abstract: XPS measurements of coarse-grained and nanostructured nitinol (Ni(50.2) Ti(49.8) ) before and after chemical treatment in hydrofluoric acid (40% HF, 1 min) are presented. The nanostructured state, providing the excellent mechanical properties of nitinol, is achieved by severe plastic deformation. The near-surface layers of nitinol were studied by XPS depth profiling. According to the obtained results, a chemical treatment in hydrofluoric acid reduces the thickness of the protective TiO(2) oxide layer and induces a nickel release from the nitinol surface and an arsenic contamination, and can therefore not be recommended as conditioning to increase the roughness of NiTi-implants. A detailed evaluation of the resulting toxicological risks is given. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.",
Arsenic,2278250,"Evaluation of trace elements in selected foods and dietary intake by young children in Thailand Abstract: Elemental concentrations in rice, animal products, eggs, vegetables, fruits, infant formulas and drinking water were determined in 667 food samples randomly collected from local markets, big supermarkets and grocery stores in Bangkok, Thailand, during the period October 2005–August 2008. Samples were digested with nitric acid and analysed by inductively coupled plasma–mass spectrometry. Arsenic and cadmium levels in most foods were below the maximum levels as set by international organisations. Filtered and bottled drinking water, rice, vegetables and banana contained low concentrations of arsenic, cadmium and lead. Non-polished rice had higher magnesium, calcium, manganese, iron and selenium concentrations than polished rice. Banana was a major source for manganese and selenium. Pig kidney and liver contained high levels of arsenic and cadmium. Manganese, cadmium, lead and aluminium concentrations in soybean milk could also be of concern. With respect to food safety for children, the amounts of arsenic and cadmium ingested with poultry, pig liver or rice corresponded to high weekly or monthly intake.",
Arsenic,1026439,"Arsenic mitigation in Bangladesh: national screening data and case studies in three upazilas Abstract: Since 2000, nearly 5 million wells in Bangladesh have been tested for arsenic. Results of this survey are presented, and it is estimated that approximately 20% of tube wells nationwide contain arsenic above the drinking water limit of 50 parts per billion, with approximately 20 million people at risk of consuming water above this limit. Three case studies in arsenic mitigation are presented, which indicate that substantial progress has been made in raising awareness about arsenic. Substantial differences were found in tubewell surveys made in 2001 and 2005, with 17% of tubewells painted green in 2001 showing arsenic above 50 ppb in 2005, and 12% of tubewells painted red in 2001 showing 50 ppb arsenic or less in 2005. In 38% of households having red tubewells, household water was found to contain 50 ppb arsenic or less, indicating substantial behaviour change. In two upazilas where safe alternatives (primarily safe shallow tubewells and newly installed deep tubewells) are available, 52% and 75% of people at risk were found to have arsenic-safe water in the household, indicating that they have changed their drinking water sources. In a third upazila where safe alternatives are scarce, less than 10% of people at risk were found to have safe water in the home. The greatest challenges remain in areas where contamination is high but installation of new safe water points is constrained for technical reasons (e.g. unsuitability of the deep aquifer).",
Arsenic,1031537,"Exposure of pesticide applicators to arsenic acid Abstract: The arsenic content of long-sleeved coveralls worn by ground rig drivers, pilots, and ground crew members averaged 430, 260 and 348 mg of arsenic, respectively after being worn during the normal pursuit of the application of arsenic acid as a desiccant on cotton in Texas and Oklahoma. The average arsenic content in breathing zone air for ground rig applicators was 7.8 microgram As/m3 during the application. The applicators coveralls received only about 0.1 to 50 ml of the applied spray. The results will aid in the determination of preliminary hazards of exposure to arsenic acid spray when the expected absorption percentage of arsenic from clothing and bare skin is determined at some future date.",
Arsenic,1026450,"Individual lifetime exposure to inorganic arsenic using a space-time information system Abstract: <strong>OBJECTIVES: </strong>A space-time information system (STIS) based method is introduced for calculating individual-level estimates of inorganic arsenic exposure over the adult life-course. STIS enables visualization and analysis of space-time data, overcoming some of the constraints inherent to spatial-only Geographic Information System software. The power of this new methodology is demonstrated using data from southeastern Michigan where 8% of the population is exposed to arsenic &gt;10 microg/l (the World Health Organization guideline) in home drinking water.<br /><br /><strong>METHODS: </strong>Participants (N=440) are members of a control group in a population-based bladder cancer case-control study in southeastern Michigan and were recruited by phone using random digit dialing. Water samples were collected and analyzed for arsenic at current residence and participants were required to answer questions concerning lifetime mobility history and dietary habits. Inorganic arsenic concentrations were estimated at past residences and workplaces, and in select foods. Fluid and food consumption data were integrated with mobility histories and arsenic concentrations to calculate continuous estimates of inorganic arsenic intake over the adult life-course.<br /><br /><strong>RESULTS: </strong>Estimates of continuous arsenic exposure are displayed, making use of both participant age and calendar year as measures of time. Results illustrate considerable temporal variability in individual-level exposure, with 26% of the participants experiencing a change in drinking water arsenic concentration of at least +/-10 microg/l over their adult lives. The average cumulative intake over the adult life-course ranges from 2.53 x 10(4)-1.30 x 10(5) microg, depending on the selected exposure metric.<br /><br /><strong>CONCLUSIONS: </strong>The STIS-based exposure assessment method allows for flexible inclusion of different parameters or alternative formulations of those parameters, thus enabling the calculation of different exposure metrics. This flexibility is particularly useful when additional exposure routes are considered, input datasets are updated, or when a scientific consensus does not exist regarding the proper formulation of the exposure metric. These results demonstrate the potential of STIS as a useful tool for calculating continuous estimates of adult lifetime exposure to arsenic or other environmental contaminants for application in exposure and risk assessment.",
Arsenic,1234306,"The role of oxidative stress in the modulation of aryl hydrocarbon receptor-regulated genes by As3+, Cd2+, and Cr6+ Abstract: Heavy metals alter the capacity of AhR ligands to induce the bioactivating phase I and the detoxifying phase II xenobiotic-metabolizing enzymes but the mechanism(s) remain unknown. In the present study, we evaluated the role of As(3+)-, Cd(2+)-, and Cr(6+)-induced oxidative stress on the expression of Cyp1a1, Nqo1, and Gst ya in Hepa 1c1c7 cells. Both Cd2+ and Cr6+, but not As3+, increased the production of ROS. However, all metals increased cellular GSH content and heme oxygenase-1 mRNA levels. Although all three metals inhibited the induction of Cyp1a1 activity by TCDD, Cyp1a1 mRNA levels were potentiated. When cellular GSH was depleted with buthionine-(S,R)-sulfoximine (BSO), Cyp1a1 mRNA expression was further potentiated whereas Cyp1a1 activity was further inhibited. In parallel, pretreatment with the antioxidant N-acetylcysteine (NAC) did not alter Cyp1a1 mRNA expression but completely abrogated the inhibition of Cyp1a1 activity induction by all three metals. On the other hand, all three metals, alone or in the presence of TCDD, enhanced Nqo1 and Gst ya mRNA levels and Nqo1 activity. These effects were potentiated in the presence of BSO and abrogated with NAC. Our data clearly show that As(3+)-, Cd(2+)-, and Cr(6+)-induced oxidative stress modulates Cyp1a1 at transcriptional and posttranscriptional levels but induces Nqo1 and Gst ya at the transcriptional level.",
Arsenic,2345650,"Biochemical and histopathological effects of subchronic oral exposure of rats to a mixture of five toxic elements Abstract: Arsenic, cadmium, lead, chromium and mercury are toxic elements that occur with high frequency in the soil and thus in agricultural products in China. To explore their combined effects, thirty male and thirty female Sprague–Dawley rats were orally exposed to a mixture of these elements at high dose (2.11, 6.47, 72.82, 2.26 and 2.71 mg/kg bw/day), medium dose (1/10 of the high dose) and low dose (1/100 of the high dose) via their drinking water for 90 days. The results revealed that BUN increased in all rats given the high dose, and serum creatinine increased in female rats given the medium dose. Decreased ALP levels in all treated male rats accompanied decreased RBC counts. In the high dose group, serum albumin, globulin and total protein content decreased in male rats, whereas serum ALT levels increased in female rats. Pathological changes were observed in the hepatocytes and renal tubules of all rats given the high dose, and the numbers of spermatogenic cells and sperm significantly decreased in both the epididymides and testes of the rats given the high dose. Abnormalities were observed earlier and more clearly in the males than in the females under combined exposure.",
Arsenic,2298746,"Arsenic removal in a sulfidogenic fixed-bed column bioreactor Abstract: In the present study, the bioremoval of arsenic from synthetic acidic wastewater containing arsenate (As(5+)) (0.5-20mg/L), ferrous iron (Fe(2+)) (100-200mg/L) and sulfate (2000mg/L) was investigated in an ethanol fed (780-1560mg/L chemical oxygen demand (COD)) anaerobic up-flow fixed bed column bioreactor at constant hydraulic retention time (HRT) of 9.6h. Arsenic removal efficiency was low and averaged 8% in case iron was not supplemented to the synthetic wastewater. Neutral to slightly alkaline pH and high sulfide concentration in the bioreactor retarded the precipitation of arsenic. Addition of 100mg/L Fe(2+) increased arsenic removal efficiency to 63%. Further increase of influent Fe(2+) concentration to 200mg/L improved arsenic removal to 85%. Decrease of influent COD concentration to its half, 780mg/L, resulted in further increase of As removal to 96% when Fe(2+) and As(5+) concentrations remained at 200mg/L and 20mg/L, respectively. As a result of the sulfidogenic activity in the bioreactor the effluent pH and alkalinity concentration averaged 7.4±0.2 and 1736±239mg CaCO3/L respectively. Electron flow from ethanol to sulfate averaged 72±10%. X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the nature of the precipitate generated by sulfate reducing bacteria (SRB) activity. Precipitation of arsenic in the form of As2S3 (orpiment) and co-precipitation with ferrous sulfide (FeS), pyrite (FeS2) or arsenopyrite (FeAsS) were the main arsenic removal mechanisms.",
Arsenic,8256,"Solubility, retention, and metabolism of intratracheally or orally administered inorganic arsenic compounds in the hamster Abstract: The absorption, biotransformation, and tissue retention of arsenic following intratracheal and oral administration of 74As-labeled sodium arsenite, sodium arsenate, arsenic trisulfide (suspension), and lead arsenate (suspension) have been studied in hamsters, and correlated to the in vitro and in vivo solubility of the compounds. After intratracheal instillation, the clearance of 74As from the lungs was positively correlated to the in vivo solubility. Less than 0.1% of the sodium arsenite and sodium arsenate was retained in the lungs after 3 days, compared to 1.3% of the arsenic trisulfide particles and 45% of the lead arsenate particles. The latter showed a very low solubility both in vivo and in vitro. In general, orally administered arsenic had a shorter biological half-life than intratracheally administered, especially when given in the form of arsenic trisulfide or lead arsenate particles, which seemed to be absorbed to only 20-30% in the gastrointestinal tract. Reduction, oxidation, and methylation of arsenic varied to a great extent with the arsenic compound and the route of exposure. Trivalent arsenic was methylated to a greater extent than pentavalent and less soluble compounds (suspended particles) more than dissolved compounds. The trivalent arsenic compounds caused higher concentrations than the pentavalent in the upper gastrointestinal tract but not in other tissues.",
Arsenic,2279119,"Evaluation of the phytostabilisation efficiency in a trace elements contaminated soil using soil health indicators Abstract: The efficiency of a remediation strategy was evaluated in a mine soil highly contaminated with trace elements (TEs) by microbiological, ecotoxicological and physicochemical parameters of the soil and soil solution (extracted in situ), as a novel and integrative methodology for assessing recovery of soil health. A 2.5-year field phytostabilisation experiment was carried out using olive mill-waste compost, pig slurry and hydrated lime as amendments, and a native halophytic shrub (Atriplex halimus L.). Comparing with non-treated soil, the addition of the amendments increased soil pH and reduced TEs availability, favoured the development of a sustainable vegetation cover (especially the organic materials), stimulated soil microorganisms (increasing microbial biomass, activity and functional diversity, and reducing stress) and reduced direct and indirect soil toxicity (i.e., its potential associated risks). Therefore, under semi-arid conditions, the use of compost and pig slurry with A. halimus is an effective phytostabilisation strategy to improve soil health of nutrient-poor soils with high TEs concentrations, by improving the habitat function of the soil ecosystem, the reactivation of the biogeochemical cycles of essential nutrients, and the reduction of TEs dissemination and their environmental impact.",
Arsenic,2064300,"Equilibrium leaching of toxic elements from cement stabilized soil Abstract: The toxicity characteristics leaching procedure (TCLP) is commonly used to assess the efficiency of solidification/stabilization (S/S) of pollutants in wastes, despite recent objections to this method. In this study, formulations of 7, 10, 15 and 20% (w/w) of calcium aluminate cement (CAC) and sulfate resistant Portland cement (SRC) were used for S/S of soil from brownfield contaminated with 43,149, 10,115, 7631, 6130, 90, 82 mg kg(-1) of Zn, Pb, Cu, As, Cd and Ni, respectively. CAC produced S/S soil monoliths of higher mechanical strength (up to 7.65 N mm(-2)). Mass-transfer analysis indicated surface wash-off as a mechanism of toxic elements release, and equilibrium leaching as a crucial parameter of S/S efficiency assessment. In the expected range of field soil pH after S/S (pH 7-9), the TCLP gave markedly different results than the multi-point pH equilibrium leaching method (using nine targeted pH values): up to 2953-, 94-, 483-, 1.3-, 27- and 1.5-times more Zn, Pb, Cu, As, Cd and Ni, respectively, was determined in the TCLP leachate. S/S with CAC reduced leachability of toxic elements more effectively than SRC. Our results indicate that, under given field conditions, the TCLP significantly underrates the efficiency of S/S of contaminated soil with cementitious binders.",
Arsenic,1579297,"Genome sequences of two dehalogenation specialists - Dehalococcoides mccartyi strains BTF08 and DCMB5 enriched from the highly polluted Bitterfeld region Abstract: The genomes of two novel Dehalococcoides mccartyi strains, DCMB5 and BTF08, enriched from the heavily organohalide-contaminated megasite around Bitterfeld (Germany), were fully sequenced and annotated. Although overall similar, the genome sequences of the two strains reveal remarkable differences in their genetic content, reflecting a specific adaptation to the contaminants at the field sites from which they were enriched. The genome of strain BTF08 encodes for 20 reductive dehalogenases, including all three of which are necessary to couple the reductive dechlorination of PCE to ethene to growth. The genes encoding trichloroethene and vinyl chloride reductive dehalogenases, tceA and vcrA, are located within mobile genetic elements, suggesting their recent horizontal acquisition. The genome of strain DCMB5 contains 23 reductive dehalogenase genes, including cbrA, which encodes a chlorobenzene reductive dehalogenase, and a gene cluster encoding arsenic resistance proteins, both corresponding to typical pollutants at its isolation site.",
Arsenic,1794817,EVALUATION OF CHROMOSOME ABERRATIONS INDUCED BY DIGOXIN IN CHINESE HAMSTER OVARY CELLS Abstract: ,
Arsenic,1356975,"Altered gene expression patterns to predict and understand chemical teratogenesis Abstract: The Human Genome Project is progressing towards completion, providing a wealth of information in the form of expressed sequence tags (ESTs), single nucleotide polymorphisms (SNPs) and physically mapped genes to the research community. As a result, toxicologists are now able to incorporate this information into their research programs, enabling them to easily efficiently perform studies that were once regarded as possible only by molecular geneticists. These new technologies have created the situation where many long sought after interactions between environmental toxicants and their gene targets can finally be addressed. Perhaps the most important development is the existence of expression chips or DNA microarrays. With these DNA chips, investigators can detect and simultaneously monitor the expression of ordered sets of hundreds or thousands of genes from small biological samples. The application of these experimental approaches to understanding the mechanisms underlying teratogen-induced congenital defects will be the focus of this presentation. Experimental examples will include both pharmaceutical compounds (valproic acid and phenytoin) and environmental contaminants (arsenic). Specific target genes include: cell cycle checkpoint genes, folate biosynthesis pathway genes, and selected transcription factors. Efforts to understand the implications of the gene expression data will be fully explored, including experimental approaches to validate gene expression observations.",
Arsenic,1017528,"Mitochondria are the main target organelle for trivalent monomethylarsonous acid (MMA(III))-induced cytotoxicity Abstract: Excessive generation of reactive oxygen species (ROS) is considered to play an important role in arsenic-induced carcinogenicity in the liver, lungs, and urinary bladder. However, little is known about the mechanism of ROS-based carcinogenicity, including where the ROS are generated, and which arsenic species are the most effective ROS inducers. In order to better understand the mechanism of arsenic toxicity, rat liver RLC-16 cells were exposed to arsenite (iAs(III)) and its intermediate metabolites [i.e., monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III))]. MMA(III) (IC(50) = 1 ?M) was found to be the most toxic form, followed by DMA(III) (IC(50) = 2 ?M) and iAs(III) (IC(50) = 18 ?M). Following exposure to MMA(III), ROS were found to be generated primarily in the mitochondria. DMA(III) exposure resulted in ROS generation in other organelles, while no ROS generation was seen following exposures to low levels of iAs(III). This suggests the mechanisms of induction of ROS are different among the three arsenicals. The effects of iAs(III), MMA(III), and DMA(III) on activities of complexes I-IV in the electron transport chain (ETC) of rat liver submitochondrial particles and on the stimulation of ROS production in intact mitochondria were also studied. Activities of complexes II and IV were significantly inhibited by MMA(III), but only the activity of complexes II was inhibited by DMA(III). Incubation with iAs(III) had no inhibitory effects on any of the four complexes. Generation of ROS in intact mitochondria was significantly increased following incubation with MMA(III), while low levels of ROS generation were observed following incubation with DMA(III). ROS was not produced in mitochondria following exposure to iAs(III). The mechanism underlying cell death is different among As(III), MMA(III), and DMA(III), with mitochondria being one of the primary target organelles for MMA(III)-induced cytotoxicity.",
Arsenic,1936023,"Outcomes and xerostomia after postoperative radiotherapy for oral and oropharyngeal carcinoma Abstract: Background: We compared outcomes and xerostomia grade after postoperative IMRT and conventional radiotherapy in patients with oral and oropharyngeal carcinoma. Methods: Eighty-eight patients with oral cavity (n=77) and oropharyngeal (n=11) carcinoma underwent postoperative IMRT (n=44) or conventional radiotherapy (CRT) (n=44). Outcomes, failure patterns, volume, doses, salivary gland V30, and xerostomia grade were evaluated. The median follow-up was 53 months (range, 48-58 months). The median interval from surgery to RT was 4 weeks (range, 3-6 weeks). Results: Twenty-one patients (7 and 14 for the IMRT and CRT groups, respectively) experienced local-regional failure. For the IMRT group, all 7 local-regional failures occurred in the high-dose target volumes. For the CRT group, there were 12 in-field failures, 1 at the margin, and 1 out-of-field. Nine patients experienced distant failure (5 and 4 for the IMRT and CRT groups, respectively). The 4-year local-regional control, disease-free survival, overall survival, and distant-metastasis rates for the IMRT and conventional radiotherapy groups were 84.1% vs. 68.2% (p = 0.055), 68.2% vs. 52.3% (p = 0.091), 70.5% vs. 56.8% (p = 0.124), and 11.4% vs. 9.1% (p = 0.927), respectively. Xerostomia grade after radiotherapy was lower for IMRT compared with conventional radiotherapy (p&lt;0.001). Conclusions: Postoperative IMRT for oral and oropharyngeal carcinoma significantly improves mean dose, salivary gland V30, and xerostomia grade when compared with conventional radiotherapy. The predominant failure pattern was local. No differences were found in survival outcomes between both groups. There was a marginal difference in local-regional control. Head Neck, 2013.",
Arsenic,8261,"A new method for the analysis of cohort studies: Implications of the multistage theory of carcinogenesis applied to occupational arsenic exposure Abstract: Implications of the multistage theory of carcinogenesis for evaluating the effect of exposure to carcinogens in the workplace are described. This theory predicts different patterns of excess risk related to duration of exposure, age at initial exposure, and follow-up time since exposure stopped, depending upon which stage of the carcinogenic process is affected by the carcinogen, i.e., action at an early stage or a late stage. New statistical methodologies are proposed to examine these patterns and are applied to the lung cancer mortality experience from a cohort study of smelter workers exposed to arsenic. Under this multistage hypothesis, the results indicate that arsenic exerts a definite late stage effect though an additional effect at the initial stage cannot be ruled out. The possibilities of biased conclusions resulting from incomplete exposure histories and lack of smoking information are also discussed as well as implications of these results to experimental animal studies.",
Arsenic,2278348,"Coordinated transcriptional regulation of Hspa1a gene by multiple transcription factors: Crucial roles for HSF-1, NF-Y, NF-?B, and CREB Abstract: Although the transcript level of inducible heat shock protein 70.3 (Hsp70.3, also known as Hspa1a) is altered in various disease states, its transcriptional regulation remains incompletely understood. Here, we systematically analyzed the Hspa1a promoter to identify major cis elements and transcription factors that may govern the constitutive/inducible gene expression. Computational analyses coupled with extensive in vitro (promoter-reporter activity and electrophoretic mobility shift assays) and in vivo (chromatin immunoprecipitation assays) revealed interaction of several transcription factors with Hspa1a promoter motifs: HSF-1 (heat shock factor 1) at -114/-97 bp and -788/-777bp, NF-Y (nuclear transcription factor Y) at -73/-58 bp, NF-?B (nuclear factor kappa B) at -133/-124 bp, and CREB (cAMP response element binding protein) at -483/-476 bp. Consistently, siRNA (small interfering RNA)-mediated down-regulation of each of these transcription factors caused substantial reduction of endogenous Hspa1a expression. Heat-shock-induced activation of Hspa1a was coordinately regulated by HSF-1 and NF-Y/NF-?B. The Hspa1a expression was augmented by TNF-? (tumor necrosis factor-alpha) and forskolin in NF-?B and CREB-dependent manners, respectively. NF-?B and CREB also activated Hspa1a transcription in cardiac myoblasts upon exposure to ischemia-like conditions. Taken together, this study discovered previously unknown roles for NF-?B and CREB to regulate Hspa1a expression and a coordinated action by several transcription factors for Hspa1a transactivation under heat-shock/ischemia-like conditions and thereby provided new insights into the mechanism of Hspa1a regulation.",
Arsenic,1033966,"Urinary arsenic, chromium, and copper levels in workers exposed to arsenic-based wood preservatives Abstract: Urinary excretion of arsenic, chromium, and copper in workers exposed to arsenic-based wood preservatives was examined to evaluate occupational exposure to these chemicals. Spot urine samples were collected from 89 wood treaters and a comparison group of 232 individuals with no known exposure to arsenicals. The results of urinalysis revealed that the wood treaters averaged 103 micrograms arsenic/L while the comparison group averaged 74 micrograms arsenic/L. The mean urinary chromium and copper levels of the wood treaters were 41 micrograms chromium/L and 191 micrograms copper/L compared with 63 micrograms chromium/L and 221 micrograms copper/L for the comparison group. Covariance analysis of urinary arsenic level between the exposed and comparison groups revealed that the adjusted mean arsenic levels of the exposed population (78 to 122 micrograms arsenic/L) were significantly higher than that of the comparison group (72 micrograms arsenic/L). The adjusted mean urinary arsenic levels of these wood treaters, however, were within published normal limits. Analysis of covariance allowed comparison of group means after statistical adjustments for possible confounding variables such as seafood intake and age. The results indicate that urinary arsenic values can provide a useful index of occupational exposure to chromated copper arsenate wood preservatives, when the effects of dietary arsenic are controlled statistically.",
Arsenic,1797853,"An End-on-Coordinated As4 Tetrahedron Abstract: One time only: The reaction of [Cp*Ru(dppe)Cl] with the potent As4 transfer reagent [Ag(?(2) -As4 )2 ](+) [pftb](-) leads to [Cp*Ru(dppe)(?(1) -As4 )](+) [pftb](-) with an unprecedented end-on-coordinated As4 tetrahedron. Reaction with a second cationic ruthenium complex fragment does not lead to a second end-on coordination but to the cleavage of one basal As?As bond. This behavior, which differs from its phosphorus analogues, is rationalized by DFT calculations.",
Arsenic,628407,"Enzymatic methylation of arsenic compounds: III. The marmoset and tamarin, but not the rhesus, monkeys are deficient in methyltransferases that methylate inorganic arsenic Abstract: The methylation of inorganic arsenic to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) have been generally considered to be the major pathway for inorganic arsenic biotransformation and detoxification. Yet, when arsenate/arsenite is injected into the Callithrix jacchus (marmoset) monkey or chimpanzee, monomethylarsonic acid and dimethylarsinic acid are not found in the urine. With the development of a rapid assay for the methyltransferases of arsenic metabolism, we have investigated the methyltransferases of the marmoset monkey liver. We have found that the marmoset, a New World animal, is deficient in liver arsenite and monomethylarsonic acid methyltransferase activities. However, the rhesus monkey, an Old World animal, has ample amounts of such methyltransferase activities. The tamarin, another New World species, is also deficient in these methyltransferases. Polymorphism and deficiency of these methyltransferases may have allowed high levels of arsenite to be maintained in the blood and liver of the marmoset and tamarin. Such high levels of arsenite may have been selective for survival of the species. The rhesus liver methyltransferases for arsenite and MMA have been purified and found to have some properties different from those of the previously reported purified rabbit liver activities. The rhesus and rabbit liver arsenite and MMA methyltransferases are devoid of catechol O-methyltransferase activity.",
Arsenic,1240082,"Production of metallothionein and heat-shock proteins in response to metals Abstract: Acute stress, such as heat, and some metals, such as arsenite, will induce a specific group of stress proteins referred to as heat-shock proteins. The heat-shock proteins contribute to the survival of cells following a variety of stresses. Similarly, metals such as cadmium and zinc, will increase the levels of metallothionein (MT). The metal-binding protein, MT, has also been found to have a protective role in the cellular response to acute stresses like heavy metals. The purpose of the present study was to examine the production of these proteins in response to metals. Rat hepatocytes were maintained in monolayer culture for 22 hr, and subsequently treated with various concentrations of metals for 4 hr, or incubated at 43.5 degrees C for 15-60 min. Following two washes with fresh media, the cells were labeled with [35S]-methionine (25 microCi/ml) in methionine-free media for 4 hr for determination of heat-shock protein production, or reincubated in fresh media for 20 hr for MT determination. Heat-shock protein production was determined by SDS-polyacrylamide gel electrophoresis followed by autoradiography. The autoradiograms were quantified by densitometric scanning. MT was determined by the Cd/hemoglobin affinity assay. Three metals (arsenite, cadmium, and zinc) strongly increased the heat-shock proteins. Whereas arsenite was a much less effective inducer of MT than was cadmium or zinc, arsenite was as effective as the other metals in inducing heat-shock proteins. Nickel was a good inducer of MT; however, it resulted in only a slight increase in the levels of heat-shock proteins.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,2345689,"Efficiency of soil organic and inorganic amendments on the remediation of a contaminated mine soil: I. Effects on trace elements and nutrients solubility and leaching risk Abstract: A mesocosm experiment, in columns, was conducted in a growth chamber to assess the viability of two organic materials (pig slurry and compost; in combination with hydrated lime) for the remediation of a highly acidic and trace elements (TEs) contaminated mine soil and the reduction of its associated leaching risks. Their influence on the evolution throughout the soil depth of the physicochemical properties (including TEs mobility) of the soil and soil solution (in situ periodic collection) and on Lolium perenne growth and foliar TEs accumulation was evaluated. Soluble and extractable concentrations of the different TEs were considerably high, although the organic amendments (with lime) and lime addition successfully decreased TEs mobility in the top soil layer, as a consequence of a rise in pH and changes in the redox conditions. Compost and pig slurry increased the soluble organic-C and dissolved N, K and P of the soil, producing a certain downwards displacement of N and K. The organic amendments allowed the growth of L. perenne in the soil, thus indicating improvement of soil conditions, but elevated TEs availability in the soil led to toxicity symptoms and abnormally high TEs concentrations in the plants. An evaluation of the functioning and ecotoxicological risks of the remediated soils is reported in part II: this allows verification of the viability of the amendments for remediation strategies.",
Arsenic,1020187,"Determination of arsenic metabolic complex excreted in human urine after administration of sodium 2,3-dimercapto-1-propane sulfonate Abstract: Sodium 2,3-dimercapto-1-propane sulfonate (DMPS) has been used to treat acute arsenic poisoning. Presumably DMPS functions by chelating some arsenic species to increase the excretion of arsenic from the body. However, the excreted complex of DMPS with arsenic has not been detected. Here we describe a DMPS complex with monomethylarsonous acid (MMA(III)), a key trivalent arsenic in the arsenic methylation process, and show the presence of the DMPS-MMA(III) complex in human urine after the administration of DMPS. The DMPS-MMA(III) complex was characterized using electrospray tandem mass spectrometry and determined by using HPLC separation with hydride generation atomic fluorescence detection (HGAFD). The DMPS-MMA(III) complex did not form a volatile hydride with borohydride treatment. On-line digestion with 0.1 M sodium hydroxide following HPLC separation decomposed the DMPS-MMA(III) complex and allowed for the subsequent quantification by hydride generation atomic fluorescence. Arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)), dimethylarsinic acid (DMA(V)), MMA(III), and DMPS-MMA(III) complex were analyzed in urine samples from human subjects collected after the ingestion of 300 mg of DMPS. The administration of DMPS resulted in a decrease of the DMA(V) concentration and an increase of the MMA(V) concentration excreted in the urine, confirming the previous results. The finding of the DMPS-MMA(III) complex in human urine after DMPS treatment provides an explanation for the inhibition of arsenic methylation by DMPS. Because MMA(III) is the substrate for the biomethylation of arsenic from MMA(V) to DMA(V), the formation of DMPS-MMA(III) complex would reduce the availability of MMA(III) for the subsequent biomethylation.",
Arsenic,1015874,"Renal, hepatic, pulmonary and adrenal tumors induced by prenatal inorganic arsenic followed by dimethylarsinic acid in adulthood in CD1 mice Abstract: Inorganic arsenic, an early life carcinogen in humans and mice, can initiate lesions promotable by other agents in later life. The biomethylation product of arsenic, dimethylarsinic acid (DMA), is a multi-site tumor promoter. Thus, pregnant CD1 mice were given drinking water (0 ppm or 85 ppm arsenic) from gestation day 8 to 18 and after weaning male offspring received DMA (0 ppm or 200 ppm; drinking water) for up to 2 years. No renal tumors occurred in controls or DMA alone treated mice while gestational arsenic exposure plus later DMA induced a significant renal tumor incidence of 17% (primarily renal cell carcinoma). Arsenic plus DMA or arsenic alone also increased renal hyperplasia over control but DMA alone did not. Arsenic alone, DMA alone and arsenic plus DMA all induced urinary bladder hyperplasia (33-35%) versus control (2%). Compared to control (6%), arsenic alone tripled hepatocellular carcinoma (20%), and arsenic plus DMA doubled this rate again (43%), but DMA alone had no effect. DMA alone, arsenic alone, and arsenic plus DMA increased lung adenocarcinomas and adrenal adenomas versus control. Overall, DMA in adulthood promoted tumors/lesions initiated by prenatal arsenic in the kidney and liver, but acted independently in the urinary bladder, lung and adrenal.",
Arsenic,62189,"Pulmonary clearance and toxicity of respirable gallium arsenide particulates intratracheally instilled into rats Abstract: Gallium arsenide (GaAs) is an intermetallic compound that is recognized as a potential toxicological risk to workers occupationally exposed to its dust. Previous results have shown that rats intratracheally instilled with a fraction of GaAs particulates, characterized with a mean count diameter of 8.30 microns and a mean volume diameter of 12.67 microns, developed signs of systemic arsenic intoxication, pulmonary inflammation, and pneumocyte hyperplasia. The results of the present study confirm these findings and also show that a significantly smaller fraction of GaAs is a relatively more severe pneumotoxicant. Decreasing the particle mean count and mean volume diameter to 1.63 micron and 5.82 microns, respectively, increased the in vivo dissolution rate of GaAs, increased the severity of pulmonary lesions previously associated with GaAs exposure, and resulted in unique pathological sequelae in affected lung tissue. Pulmonary fibrosis, as indicated by analysis of lung 4-hydroxyproline content, was not considered statistically significant although histological examination of lung tissue revealed a mild fibrotic response. These results provide additional evidence that pulmonary exposure to respirable GaAs particulates is a potential health hazard in the semiconductor industry.",
Arsenic,1794820,"Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia Abstract: This paper presents the first gaseous elemental mercury (GEM) air-surface exchange measurements obtained over naturally enriched and background (<0.1 ?g g?1 Hg) terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and winter periods at a copper-gold-cobalt-arsenic-mercury mineral field near Pulganbar, NSW. GEM fluxes using a dynamic flux chamber approach were measured, along with controlling environmental parameters over three naturally enriched and three background substrates. The enriched sites results showed net emission to the atmosphere and a strong correlation between flux and substrate Hg concentration, with average fluxes ranging from 14 ± 1 ng m?2 h?1 to 113 ± 6 ng m?2 h?1. Measurements at background sites showed both emission and deposition. The average Hg flux from all background sites showed an overall net emission of 0.36 ± 0.06 ng m?2 h?1. Fluxes show strong relationships with temperature, radiation, and substrate parameters. A compensation point of 2.48, representative of bare soils was determined. For periods of deposition, dry deposition velocities ranged from 0.00025 cm s?1 to 0.0083 cm s?1 with an average of 0.0041 ± 0.00018 cm s?1, representing bare soil, nighttime conditions. Comparison of the Australian data to North American data suggests the need for Australian-specific mercury air-surface exchange data representative of Australia's unique climatic conditions, vegetation types, land use patterns and soils.",
Arsenic,2064233,"LC-ICP-MS analysis of arsenic compounds in dominant seaweeds from the Thermaikos Gulf (Northern Aegean Sea, Greece) Abstract: The content of total arsenic and arsenic compounds in the dominant seaweed species in the Thermaikos Gulf, Northern Aegean Sea was determined in samples collected in different seasons. Total arsenic was determined by acid digestion followed by ICP-MS. Arsenic speciation was analyzed by water extraction followed by LC-ICP-MS. Total arsenic concentrations in the seaweeds ranged from 1.39 to 55.0mgkg(-1). Cystoseira species and Codium fragile showed the highest total As contents, while Ulva species (U. intestinalis, U. rigida,U. fasciata) had the lowest Arsenosugars, the most common arsenic species in seaweeds, were found in all samples, and glycerol-arsenosugar was the most common form; however, phosphate-arsenosugar and sulfate-arsenosugar were also present. Inorganic arsenic was measured in seven algae species and detected in another. Arsenate was the most abundant species in Cystoseira barbata (27.0mgkg(-1)). Arsenobetaine was measured in only one sample. Methylated arsenic species were measured at very low concentrations. The information should contribute to further understanding the presence of arsenic compounds in dominant seaweeds from the Thermaikos Gulf.",
Arsenic,1508649,"Application of zirconium-iridium permanent modifier for the simultaneous determination of lead, cadmium, arsenic, and nickel in atmospheric particulate matter by multi-element electrothermal atomic absorption spectrometry Abstract: A novel and robust method for the simultaneous determination of lead, cadmium, arsenic, and nickel in atmospheric particulate matter by multi-element electrothermal atomic absorption spectrometry was developed, using zirconium-iridium coating as permanent modifier (140 ?g Zr and 4 ?g Ir). After 300 atomization cycles, it was necessary to add 2 ?g of Ir. Due to the varying concentrations of Pb in atmospheric particulate matter, lead was monitored at two wavelengths, at the less sensitive line of 261.4 nm for high concentration samples (&gt;20 ?g?L(-1)) or at 283.3 nm for the low concentration samples. Matrix-matched calibration had to be performed for quantitative recoveries (96-102 %). Following this approach, the four elements were determined in atmospheric particulate matter samples from an industrial area near the city of Athens in two different time periods (cold-warm) with limits of detection of 5.5 ng?m(-3) for Pb at 261.4 nm and 0.29 ng?m(-3) at 283.3 nm, 0.019 ng?m(-3) for Cd, 0.14 ng?m(-3) for As, and 0.22 ng?m(-3) for Ni. Lead, Cd, and As levels were very low, whereas Ni content was at comparable levels with other areas worldwide.",
Arsenic,1576389,"Daily and hourly sourcing of metallic and mineral dust in urban air contaminated by traffic and coal-burning emissions Abstract: A multi-analytical approach to chemical analysis of inhalable urban atmospheric particulate matter (PM), integrating particle induced X-ray emission, inductively coupled plasma mass spectrometry/atomic emission spectroscopy, chromatography and thermal-optical transmission methods, allows comparison between hourly (Streaker) and 24-h (High volume sampler) data and consequently improved PM chemical characterization and source identification. In a traffic hot spot monitoring site in Madrid (Spain) the hourly data reveal metallic emissions (Zn, Cu, Cr, Fe) and resuspended mineral dust (Ca, Al, Si) to be closely associated with traffic flow. These pollutants build up during the day, emphasizing evening rush hour peaks, but decrease (especially their coarser fraction PM2.5-10) after nocturnal road washing. Positive matrix factorization (PMF) analysis of a large Streaker database additionally reveals two other mineral dust components (siliceous and sodic), marine aerosol, and minor, transient events which we attribute to biomass burning (K-rich) and industrial (incinerator?) Zn, Pb plumes. Chemical data on 24-h filters allows the measurement of secondary inorganic compounds and carbon concentrations and offers PMF analysis based on a limited number of samples but using fuller range of trace elements which, in the case of Madrid, identifies the continuing minor presence of a coal combustion source traced by As, Se, Ge and Organic Carbon. This coal component is more evident in the city air after the change to the winter heating season in November. Trace element data also allow use of discrimination diagrams such as V/Rb vs. La/Ce and ternary plots to illustrate variations in atmospheric chemistry (such as the effect of Ce-emissions from catalytic converters), with Madrid being an example of a city with little industrial pollution, recently reduced coal emissions, but serious atmospheric contamination by traffic emissions.",
Arsenic,734976,"Reversal and prevention of arsenic-induced human bronchial epithelial cell malignant transformation by microRNA-200b Abstract: Arsenic is a well-recognized human carcinogen, yet the mechanism by which it causes human cancer has not been elucidated. MicroRNAs (miRNAs) are a big family of small noncoding RNAs and negatively regulate the expression of a large number of protein-coding genes. We investigated the role of miRNAs in arsenic-induced human bronchial epithelial cell malignant transformation and tumor formation. We found that prolonged exposure of immortalized p53-knocked down human bronchial epithelial cells (p53(low)HBECs) to low levels of arsenite (NaAsO?, 2.5 ?M) caused malignant transformation that was accompanied by epithelial to mesenchymal transition (EMT) and reduction in the levels of miR-200 family members. Stably reexpressing miR-200b in arsenite-transformed cells (As-p53(low)HBECs) completely reversed their transformed phenotypes, as evidenced by inhibition of colony formation in soft agar and prevention of xenograft tumor formation in nude mice. Moreover, stably expressing miR-200b alone in parental nontransformed p53(low)HBECs was sufficient to completely prevent arsenite exposure from inducing EMT and malignant transformation. Further mechanistic studies showed that depletion of miR-200 in arsenite-transformed cells involved induction of the EMT-inducing transcription factors zinc-finger E-box-binding homeobox factor 1 (ZEB1) and ZEB2 and increased methylation of miR-200 promoters. Stably expressing ZEB1 alone in parental nontransformed p53(low)HBECs was sufficient to deplete miR-200, induce EMT and cause cell transformation, phenocopying the oncogenic effect of 16-week arsenite exposure. These findings establish for the first time a causal role for depletion of miR-200b expression in human cell malignant transformation and tumor formation resulting from arsenic exposure.",
Arsenic,579475,"Activation of protein kinase C and disruption of endothelial monolayer integrity by sodium arsenite--Potential mechanism in the development of atherosclerosis Abstract: Arsenic exposure has been shown to exacerbate atherosclerosis, beginning with activation of the endothelium that lines the vessel wall. Endothelial barrier integrity is maintained by proteins of the adherens junction (AJ) such as vascular endothelial cadherin (VE-cadherin) and [beta]-catenin and their association with the actin cytoskeleton. In the present study, human aortic endothelial cells (HAECs) were exposed to 1, 5 and 10Â [mu]M sodium arsenite [As(III)] for 1, 6, 12 and 24Â h, and the effects on endothelial barrier integrity were determined. Immunofluorescence studies revealed formation of actin stress fibers and non-uniform VE-cadherin and [beta]-catenin staining at cell-cell junctions that were concentration- and time-dependent. Intercellular gaps were observed with a measured increase in endothelial permeability. In addition, concentration-dependent increases in tyrosine phosphorylation (PY) of [beta]-catenin and activation of protein kinase C[alpha] (PKC[alpha]) were observed. Inhibition of PKC[alpha] restored VE-cadherin and [beta]-catenin staining at cell-cell junctions and abolished the As(III)-induced formation of actin stress fibers and intercellular gaps. Endothelial permeability and PY of [beta]-catenin were also reduced to basal levels. These results demonstrate that As(III) induces activation of PKC[alpha], which leads to increased PY of [beta]-catenin downstream of PKC[alpha] activation. Phosphorylation of [beta]-catenin plausibly severs the association of VE-cadherin and [beta]-catenin, which along with formation of actin stress fibers, results in intercellular gap formation and increased endothelial permeability. To the best of our knowledge, this is the first report demonstrating that As(III) causes a loss of endothelial monolayer integrity, which potentially could contribute to the development of atherosclerosis.",
Arsenic,1024707,"A versatile technique for radiochemical separation of medically useful no-carrier-added (nca) radioarsenic from irradiated germanium oxide targets Abstract: A method for the separation of no-carrier-added (nca) arsenic radionuclides from bulk amounts of irradiated germanium oxide (GeO2) target was developed in view of their potentialities in different biological and nuclear medicine applications. The beta- emitting 77As radionuclide, produced by the decay of 77Ge through the natGe(n,gamma)77Ge nuclear reaction, was used for standardization of the radiochemical separation procedure. The radiochemical separation was performed by precipitation followed by solvent extraction. About 99% post-irradiation recovery of the GeO2 target material, in a form suitable for reuse in future irradiation, was achieved. The developed method was suitable for the production of nca arsenic radionuclides either as trivalent or pentavalent arsenic in various vehicles which provided flexibility of formulations of different kinds of compound. The overall radiochemical yield for the complete separation of 77As was 90%. The separated nca 77As was of high radionuclidic purity and did not contain detectable amounts of the target material. This method can be adopted for the radiochemical separation of other different arsenic radionuclides produced from GeO2 through cyclotron as well as reactor irradiation.",
Arsenic,2088424,"The effects of large borate deposits on groundwater quality Abstract: Seydisuyu Basin, which contains very important agricultural areas and boron deposits of Turkey, is located in Eskis?ehir province. In this paper, the groundwater quality of Seydisuyu Basin was evaluated by using some physiochemical (temperature, conductivity, salinity, and demanded oxygen) and chemical (boron and arsenic) parameters. Groundwater samples were collected seasonally (2011-12) from 14 wells from the Seydisuyu Basin and all of the data obtained experimentally were compared with national and international drinking and usage water standards. Also, cluster analysis (CA) was applied to the results to classify the stations according to the contents of arsenic and boron levels by using the Past package program, factor analysis (FA) was applied to the results to classify the affective factors on groundwater quality, and Pearson Correlation Index was applied to the results to determine the relations of parameters by using the SPSS 17 package program. According to data, arsenic and boron accumulations of wells were higher than the drinking water limits specified by the Turkish Standards Institute (TS266), European Communities (EC), and World Health Organization (WHO) Drinking Water Standards. According to the results of FA, three effective factors that explain 76.36% of the total variance was detected and arsenic-boron contents of groundwater were positively loaded with the second factor, named as “Boron Works and Environmental Factor.” According to results of CA identified by using arsenic and boron accumulations, station 1, which was the closest well to the boron facility, showed the highest distance and lowest similarity with the other stations.",
Arsenic,2064125,"Evaluation of copper, lead and arsenic level in tilapia fish in Cempaka Lake (Bangi, Malaysia) and human daily/weekly intake Abstract: ",
Arsenic,1704134,"Evaluation of microbial biomass and activity in different soils exposed to Increasing level of arsenic pollution: A laboratory study Abstract: Soil contamination with arsenic is a widespread phenomenon in many parts of the world and it is well known that it may affect the soil microbial community. A laboratory experiment was performed to evaluate the acute toxicity effect of different As concentrations (0, 0.1, 1.0, 10, 100, and 200 mg/kg) on soil biological parameters like microbial biomass carbon (MBC), active microbial biomass carbon (AMBC), basal soil respiration (BSR), fluorescein diacetate hydrolase activity (FDA), and dehydrogenase activity (DHA) under three different soil types (Inceptisol, Vertisol, and Entisol). Soil enzyme activities, microbial biomass, and respiration were significantly decreased by arsenic exposure. The soil metabolic quotient increased with increasing As concentration, the maximum being observed for Entisol followed by Vertisol and Inceptisol. Except for soil enzyme activities, the majority of which started to decrease after the addition of 10 mg/kg arsenic, all other parameters decreased at arsenic dose ?0.1 mg/kg. The decrease of AMBC/MBC ratio showed that acute arsenic stress affected the active microorganisms more than the dormant component of total microbial biomass. Among the three soils studied, Vertisol was comparatively more tolerant to As exposure in terms of soil enzymes and biomass, followed by Inceptisol and Entisol. MBC has evolved as a distinct parameter in cluster analysis, while some others, such as DHA and AMBC, and FDA and BSR, appeared essentially redundant.",
Arsenic,2343495,"Arsenic and lung disease mortality in Bangladeshi adults Abstract: <strong>BACKGROUND:: </strong>Chronic arsenic exposure through drinking water is a public health problem affecting millions of people worldwide, including at least 30 million in Bangladesh. We prospectively investigated the associations of arsenic exposure and arsenical skin lesion status with lung disease mortality in Bangladeshi adults.<br /><br /><strong>METHODS:: </strong>Data were collected from a population-based sample of 26,043 adults, with an average of 8.5 years of follow-up (220,157 total person-years). There were 156 nonmalignant lung disease deaths and 90 lung cancer deaths ascertained through October 2013. We used Cox proportional hazards models to estimate adjusted hazard ratios and 95% confidence intervals (CIs) for lung disease mortality.<br /><br /><strong>RESULTS:: </strong>Creatinine-adjusted urinary total arsenic was associated with nonmalignant lung disease mortality, with persons in the highest tertile of exposure having a 75% increased risk for mortality (95% CI = 1.15-2.66) compared with those in the lowest tertile of exposure. Persons with arsenical skin lesions were at increased risk of lung cancer mortality (hazard ratio = 4.53 [95% CI = 2.82-7.29]) compared with those without skin lesions.<br /><br /><strong>CONCLUSIONS:: </strong>This prospective investigation of lung disease mortality, using individual-level arsenic measures and skin lesion status, confirms a deleterious effect of ingested arsenic on mortality from lung disease. Further investigations should evaluate effects on the incidence of specific lung diseases, more fully characterize dose-response, and evaluate screening and biomedical interventions to prevent premature death among arsenic-exposed populations, particularly among those who may be most susceptible to arsenic toxicity.",
Arsenic,627273,"Dose response evaluation of gene expression profiles in the skin of K6/ODC mice exposed to sodium arsenite Abstract: Chronic drinking water exposure to inorganic arsenic and its metabolites increases tumor frequency in the skin of K6/ODC transgenic mice. To identify potential biomarkers and modes of action for this skin tumorigenicity, we characterized gene expression profiles from analysis of K6/ODC mice administered 0, 0.05, 0.25, 1.0 and 10 ppm sodium arsenite in their drinking water for 4 weeks. Following exposure, total RNA was isolated from mouse skin and processed to biotin-labeled cRNA for microarray analyses. Skin gene expression was analyzed with Affymetrix Mouse Genome 430A 2.0 GeneChips, and pathway analysis was conducted with DAVID (NIH), Ingenuity Systems and MetaCore's GeneGo. Differential expression of several key genes was verified through qPCR. Only the highest dose (10 ppm) resulted in significantly altered KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, including MAPK, regulation of actin cytoskeleton, Wnt, Jak-Stat, Tight junction, Toll-like, phosphatidylinositol and insulin signaling pathways. Approximately 20 genes exhibited a dose response, including several genes known to be associated with carcinogenesis or tumor progression including cyclin D1, CLIC4, Ephrin A1, STAT3 and DNA methyltransferase 3a. Although transcription changes in all identified genes have not previously been linked to arsenic carcinogenesis, their association with carcinogenesis in other systems suggests that these genes may play a role in the early stages of arsenic-induced skin carcinogenesis and can be considered potential biomarkers.",
Arsenic,1021844,"Arsenic accumulation in native plants of West Bengal, India: prospects for phytoremediation but concerns with the use of medicinal plants Abstract: Arsenic (As) is a widespread environmental and food chain contaminant and class I, non-threshold carcinogen. Plants accumulate As due to ionic mimicry that is of importance as a measure of phytoremediation but of concern due to the use of plants in alternative medicine. The present study investigated As accumulation in native plants including some medicinal plants, from three districts [Chinsurah (Hoogly), Porbosthali (Bardhman), and Birnagar (Nadia)] of West Bengal, India, having a history of As pollution. A site-specific response was observed for Specific Arsenic Uptake (SAU; mg kg(?-?1) dw) in total number of 13 (8 aquatic and 5 terrestrial) collected plants. SAU was higher in aquatic plants (5-60 mg kg(?-?1) dw) than in terrestrial species (4-19 mg kg(?-?1) dw). The level of As was lower in medicinal plants (MPs) than in non-medicinal plants, however it was still beyond the WHO permissible limit (1 mg kg(?-?1) dw). The concentration of other elements (Cu, Zn, Se, and Pb) was found to be within prescribed limits in medicinal plants (MP). Among the aquatic plants, Marsilea showed the highest SAU (avg. 45 mg kg(?-?1) dw), however, transfer factor (TF) of As was the maximum in Centella asiatica (MP, avg. 1). Among the terrestrial plants, the maximum SAU and TF were demonstrated by Alternanthera ficoidea (avg. 15) and Phyllanthus amarus (MP, avg. 1.27), respectively. In conclusion, the direct use of MP or their by products for humans should not be practiced without proper regulation. In other way, one fern species (Marsilea) and some aquatic plants (Eichhornia crassipes and Cyperus difformis) might be suitable candidates for As phytoremediation of paddy fields.",
Arsenic,1519139,Arsenite removal from water by electro-coagulation on zinc-zinc and copper-copper electrodes Abstract: ,
Arsenic,2064186,"Arsenite-induced stress signaling: Modulation of the phosphoinositide 3'-kinase/Akt/FoxO signaling cascade Abstract: FoxO transcription factors and their regulators in the phosphoinositide 3'-kinase (PI3K)/Akt signaling pathway play an important role in the control of cellular processes involved in carcinogenesis, such as proliferation and apoptosis. We have previously demonstrated that physiologically relevant heavy metal ions, such as copper or zinc ions, can stimulate this pathway, triggering phosphorylation and nuclear export of FoxO transcription factors. The present study aims at investigating the effect of arsenite on FoxO transcription factors and the role of PI3K/Akt signaling therein. Exposure of HaCaT human keratinocytes to arsenite resulted in a distinct decrease of glutathione levels only at cytotoxic concentrations. In contrast, a strong phosphorylation of FoxO1a/FoxO3a and Akt was observed at subcytotoxic concentrations of arsenite in HaCaT human keratinocytes. A time- and concentration-dependent increase in phosphorylation of FoxO1a and FoxO3a at sites known to be phosphorylated by Akt as well as phosphorylation of Akt at Ser-473 was detected. These phosphorylations were blunted in the presence of wortmannin, pointing to the involvement of PI3K.",
Arsenic,1032652,"Effects of time-variant exposure on toxic substance response Abstract: Sources of time-variant exposure to toxic substances are identified and examined for their effects on the estimation of response. It is shown that only time-averaged target tissue concentrations are required to obtain rigorous risk estimates from the one-hit and multihit models. In contrast, detailed concentration histories need to be retained throughout analyses involving two-event models with intermediate-stage clonal growth advantage (clonal two-stage) and multistage models. Cumulative incidence ratios, based on the exact to time-averaged treatment of concentration time dependencies, are evaluated for substances whose toxic responses exhibit moderate (arsenic) and strong (ethylene dibromide) dependence on time of actual exposure. These ratios reveal that time-averaged dose approximations may lead to several orders of magnitude error in both the multistage and clonal two-stage models if exposure periods are short, and that 3.4-fold (arsenic) and 8-fold (ethylene dibromide) errors still exist even when an actual two-thirds lifetime exposure is averaged over a full lifetime. Finally, the effects of time-variant exposure on risk estimation due to migration and birth-death in an epidemiological setting are examined. A residence time distribution calculation shows that, if these effects are ignored for a population orally exposed to arsenic and characterized by an out-migration rate in excess of 5%/yr, response errors will exceed an order of magnitude.",
Arsenic,2278039,"Speciation analysis of arsenic in prenatal and children's dietary supplements using microwave-enhanced extraction and ion chromatography-inductively coupled plasma mass spectrometry Abstract: A study was conducted to develop a microwave-enhanced extraction method for the determination of arsenic species in prenatal and children's dietary supplements prepared from plant materials. The method was optimized by evaluating the efficiency of various solutions previously used to extract arsenic from the types of plant materials used in the dietary supplement formulations. A multivitamin standard reference material (NIST SRM 3280) and a prenatal supplement sample were analyzed in the method optimization. The identified optimum conditions were 0.25g of sample, 5mL of 0.3molL(-1) orthophosphoric acid (H3PO4) and microwave heating at 90°C for 30min. The extracted arsenic was speciated by cation exchange ion chromatography-inductively coupled plasma mass spectrometry (IC-ICP-MS). The method detection limit (MDL) for the arsenic species was in the range 2-8ngg(-1). Ten widely consumed prenatal and children's dietary supplements were analyzed using the optimized protocol. The supplements were found to have total arsenic in the concentration range 59-531ngg(-1). The extraction procedure recovered 61-92% of the arsenic from the supplements. All the supplementary products were found to contain arsenite (As(3+)) and dimethylarsinic acid (DMA). Arsenate (As(5+)) was found in two of the supplements, and an unknown specie of arsenic was detected in one product. The results of the analysis were validated using mass balance by comparing the sum of the extracted and non-extracted arsenic with the total concentration of the element in the corresponding samples.",
Arsenic,2337125,"Dissolution and Solubility of the (BaxSr1-x)HAsO4 center dot H2O Solid Solution in Aqueous Solution at 25 degrees C and pH 2 Abstract: Six different members of the (BaxSr1-x)HAsO4 center dot H2O solid solution were prepared and characterized, and then dissolution of the synthetic solids was studied at 25 degrees C and pH 2 in a series of batch experiments for 4320 h. With the increase in the Ba/(Ba + Sr) mole fraction of the solids, the aqueous pH decreased and the aqueous barium concentration increased. The aqueous strontium and arsenic concentrations had the highest values at Ba/(Ba + Sr) = 0.21. The solubility products for BaHAsO4 center dot H2O and SrHAsO4 center dot H2O were calculated to be 10(-5.52) and 10(-4.62), respectively. The corresponding free energies of formation were determined to be -1543.99 +/- 0.18 kJ/mol and -1537.94 +/- 0.02 kJ/mol. The solid solution had a minimum solubility product of 10(-5.61) at Ba/(Ba + Sr) = 0.82. The Guggenheim coefficients were determined to be a(0) = 1.55 and a(1) = -4.35. The Lippmann diagram was a typical Lippmann diagram for a nonideal solid solution with a negative enthalpy of mixing. The system shows an ""alyotropic"" minimum at the aqueous Ba/(Ba+Sr) activity fraction of 0.87 where the solutus and solidus curves meet. At the end of the dissolution experiment, the dissolution followed the saturation curve for the pure endmember BaHAsO4 center dot H2O and approached the intersection with the minimum stoichiometric saturation curve on the Lippmann diagram.",
Arsenic,628528,"Arsenic stimulates sinusoidal endothelial cell capillarization and vessel remodeling in mouse liver Abstract: Trivalent arsenic [As(III)] is a well-known environmental toxicant that causes a wide range of organ-specific diseases and cancers. In the human liver, As(III) promotes vascular remodeling, portal fibrosis, and hypertension, but the pathogenesis of these As(III)-induced vascular changes is unknown. To investigate the hypothesis that As(III) targets the hepatic endothelium to initiate pathogenic change, mice were exposed to 0 or 250 parts per billion (ppb) of As(III) in their drinking water for 5 weeks. Arsenic(III) exposure did not affect the overall health of the animals, the general structure of the liver, or hepatocyte morphology. There was no change in the total tissue arsenic levels, indicating that arsenic does not accumulate in the liver at this level of exposure. However, there was significant vascular remodeling with increased sinusoidal endothelial cell (SEC) capillarization, vascularization of the peribiliary vascular plexus (PBVP), and constriction of hepatic arterioles in As(III)-exposed mice. In addition to ultrastructural demonstration of SEC defenestration and capillarization, quantitative immunofluorescence analysis revealed increased sinusoidal PECAM-1 and laminin-1 protein expression, suggesting gain of adherens junctions and a basement membrane. Conversion of SECs to a capillarized, dedifferentiated endothelium was confirmed at the cellular level with demonstration of increased caveolin-1 expression and SEC caveolae, as well as increased membrane-bound Rac1-GTPase. Conclusion: These data demonstrate that exposure to As(III) causes functional changes in SEC signaling for sinusoidal capillarization that may be initial events in pathogenic changes in the liver.",
Arsenic,2298673,"Synthesis and Characterization of Arsenolipids: Naturally Occurring Arsenic Compounds in Fish and Algae Abstract: Arsenic-containing lipids (arsenolipids) are natural products present in fish and algae. Because these compounds occur in foods, there is considerable interest in their human toxicology. We report the synthesis and characterization of seven arsenic-containing lipids, including six natural products. The compounds comprise dimethylarsinyl groups attached to saturated long-chain hydrocarbons (three compounds), saturated long-chain fatty acids (two compounds), and monounsaturated long chain fatty acids (two compounds). The arsenic group was introduced through sodium dimethylarsenide or bis(dimethylarsenic) oxide. The latter route provided higher and more reproducible yields, and consequently, this pathway was followed to synthesize six of the seven compounds. Mass spectral properties are described to assist in the identification of these compounds in natural samples. The pure synthesized arsenolipids will be used for in vitro experiments with human cells to test their uptake, biotransformation, and possible toxic effects.",
Arsenic,1326996,"SPARC gene expression is repressed in human urothelial cells (UROtsa) exposed to or malignantly transformed by cadmium or arsenite Abstract: SPARC belongs to a class of extracellular matrix-associated proteins that have counteradhesive properties. The ability of SPARC to modulate cell-cell and cell-matrix interactions provides a strong rationale for studies designed to determine its expression in cancer. The objective of this study was to determine if SPARC expression was altered in cadmium (Cd(2+)) and arsenite (As(3+)) induced bladder cancer and if these alterations were present in archival specimens of human bladder cancer. The expression of SPARC was determined in human parental UROtsa cells, their Cd(2+) and As(3+) transformed counterparts and derived tumors, and in archival specimens of human bladder cancer using a combination of real time reverse transcriptase polymerase chain reaction, Western blotting, immunofluorescence localization and immunohistochemical staining. It was demonstrated that SPARC expression was down-regulated in Cd(2+) and As(3+) transformed UROtsa cells. In addition, the malignant epithelial component of tumors derived from these cell lines were also down-regulated for SPARC expression, but the stromal cells recruited to these tumors was highly reactive for SPARC. This finding was shown to translate to specimens of human bladder cancer where tumor cells were SPARC negative, but stromal cells were positive. Acute exposure of UROtsa cells to both cadmium and arsenite reduced the expression of SPARC through a mechanism that did not involve changes in DNA methylation or histone acetylation. These studies suggest that environmental exposure to As(3+) or Cd(2+) can alter cell-cell and cell-matrix interactions in normal urothelial cells through a reduction in the expression of SPARC. The SPARC associated loss of cell-cell and cell-matrix contacts may participate in the multi-step process of bladder carcinogenesis.",
Arsenic,1031805,"Cancer incidence and exposure to iron oxide dust Abstract: Iron oxides, particularly hematite, have been suspected for carcinogenic properties based on epidemiological observations and experimental data. This case-control (case-referent) study concerns a worker population with high exposure to dust of iron oxides, particularly hematite, and with some impurities of pentavalent arsenic and other metals. In spite of the high exposure levels no excess of cancer has been observed, either in the respiratory system or at other sites. It is suggested that earlier findings of respiratory cancers as possibly associated with iron oxides exposure might rather be due to other concomitant risk factors.",
Arsenic,1597328,"Behaviour of aluminium, arsenic and vanadium during the neutralisation of red mud leachate by HCl, gypsum, or seawater Abstract: Red mud leachate (pH 13) collected from Ajka, Hungary is neutralised to <pH 10 by HCl, gypsum or seawater addition. During acid neutralisation >99 % Al is removed from solution during the formation of an amorphous boehmite-like precipitate and dawsonite. Minor amounts of As (24 %) are also removed from solution via surface adsorption of As onto the Al oxyhydroxides. Gypsum addition to red mud leachate results in the precipitation of calcite, both in experiments and in field samples recovered from rivers treated with gypsum after the October 2010 red mud spill. Calcite precipitation results in 86 % Al and 81 % As removal from solution, and both are non-exchangeable with 0.1 mol/L phosphate solution. Contrary to As associated with neoformed Al oxyhydroxides, EXAFS analysis of the calcite precipitates revealed only isolated arsenate tetrahedra with no evidence for surface adsorption or incorporation into the calcite structure, possibly as a result of very rapid As scavenging by the calcite precipitate. Seawater neutralisation also resulted in carbonate precipitation, with >99 % Al and 74 % As removed from solution during the formation of a poorly ordered hydrotalcite phase and via surface adsorption to the neoformed precipitates, respectively. Half the bound As could be remobilised by phosphate addition, indicating that As was weakly bound, possibly in the hydrotalcite interlayer. Only 5-16 % V was removed from solution during neutralisation, demonstrating a lack of interaction with any of the neoformed precipitates. High V concentrations are therefore likely to be an intractable problem during the treatment of red mud leachates.",
Arsenic,1508671,"Implication of Organic Matter on Arsenic and Antimony Sequestration in Sediment: Evidence from Sundarban Mangrove Forest, India Abstract: This study reports the measurement of stability constants for the interaction of As (V and III) and Sb (V and III) with humic substances extracted from aquatic sediments of the Sundarban mangrove forest ecosystem. It was observed that As and Sb formed a slightly more stable association with fulvic acid (FA) than with its humic acid (HA) counterpart. Quenching of fluorescence at increasing As (III and V) or Sb (III and V): FA or HA ratios was obtained that ideally correspond to a 1:1 complexation model. Quite strong complexation of As and Sb by FA and HA occurs at neutral pH, indicating that HA and FA probably markedly affect the mobility of As and Sb in the mangrove environment.",
Arsenic,1597336,"Environmental exposure to metals and children's growth to age 5 years: A prospective cohort study Abstract: In this prospective cohort study, based on 1,505 mother-infant pairs in rural Bangladesh, we evaluated the associations between early-life exposure to arsenic, cadmium, and lead, assessed via concentrations in maternal and child urine, and children's weights and heights up to age 5 years, during the period 2001-2009. Concurrent and prenatal exposures were evaluated using linear regression analysis, while longitudinal exposure was assessed using mixed-effects linear regression. An inverse association was found between children's weight and height, age-adjusted z scores, and growth velocity at age 5 years and concurrent exposure to cadmium and arsenic. In the longitudinal analysis, multivariable-adjusted attributable differences in children's weight at age 5 years were -0.33 kg (95% confidence interval (CI): -0.60, -0.06) for high (?95th percentile) arsenic exposure and -0.57 kg (95% CI: -0.88, -0.26) for high cadmium exposure, in comparison with children with the lowest exposure (?5th percentile). Multivariable-adjusted attributable differences in height were -0.50 cm (95% CI: -1.20, 0.21) for high arsenic exposure and -1.6 cm (95% CI: -2.4, -0.77) for high cadmium exposure. The associations were apparent primarily among girls. The negative effects on children's growth at age 5 years attributable to arsenic and cadmium were of similar magnitude to the difference between girls and boys in terms of weight (-0.67 kg, 95% CI: -0.82, -0.53) and height (-1.3 cm, 95% CI: -1.7, -0.89).",
Arsenic,1597298,"Theoretical and experimental study of the vibrational spectra of sarkinite Mn2(AsO4)(OH) and adamite Zn2(AsO4)(OH) Abstract: The arsenate hydroxyl-bearing minerals sarkinite and adamite were studied with vibrational spectroscopic (IR and Raman) and quantum theoretical methods. The observed IR bands in the higher (1100-600cm(-1)) and especially lower (600-450cm(-1)) frequency region of AsO4 vibrations could clearly discriminate between the studied analogues. The differences between their crystal structures are much pronounced in both IR and Raman OH-stretching regions. Namely, a single strong band is found in the case of orthorhombic adamite compared to four weaker bands observed in corresponding IR and Raman spectral regions of monoclinic sarkinite. Essentially all bands in the experimental spectra, collected at both room and liquid nitrogen temperature, were tentatively assigned. To support the tentative assignment of bands in the vibrational spectra of the mentioned minerals, periodic pseudopotential plane wave density functional theory calculations were carried out. Geometry optimizations of the 3D periodic systems included both optimizations of the atomic positions within the unit cell and of the unit cell itself. In most cases, the assignments were either supported or implied by the obtained theoretical data. It is worth mentioning that this is the first experimental and theoretical study of the vibrational spectra of the very-rare sarkinite mineral.",
Arsenic,1016962,"Elevated blood mercury and neuro-otological observations in children of the Ecuadorian gold mines Abstract: The prevalence of mercury (Hg) intoxication was investigated in 114 Andean Saraguro and non-Saraguro (Mestizo) children living in remote gold-mining settlements in Nambija and Portovelo, Ecuador. Venous blood samples showed a mean total blood mercury (B-Hg) level of 18.2 microg/L (SD 15.5; range 2-89.) for 77 Saraguro and non-Saraguro children in the Nambija settlement, which was significantly higher than that of children in the Portovelo and reference groups. Comparison of groups showed mean B-Hg levels of 26.4 microg/L (range 4-89 microg/L) for 32 indigenous/Saraguro children; 12.3 microg/L (range 2-33 microg/L) for 45 non-Saraguro children; 4.9 microg/L (range 1-10 microg/L) for 37 children in Portovelo; and 2.4 microg/L (range 1-6 microg/L) for a reference group of 15 children. Fisher's post hoc analysis revealed significant differences among groups, except between the Portovelo and the reference groups. Neuro-otological symptoms and abnormalities were observed in Saraguro, non-Saraguro, and Portovelo children. Samples of soil collected at sites near the local school were found to contain Hg levels ranging from 0. 1 to 38 ppm, cadmium (Cd) levels from 0.07 to 0.82 ppm and arsenic (As) levels from &lt; 1 to 3.9 ppm. in conclusion, the children of Nambija, particularly the Saraguro &quot;Amer-Indians,&quot; exhibited elevated B-Hg levels from exposure to Hg used in the gold-mining process, and are at risk for neurological impairment. The children of Portovelo who reported neuro-otological symptoms but had low B-Hg levels (&lt;10 microg/L) may be affected by exposure to sodium cyanide, which is used extensively in the local gold-mining operations.",
Arsenic,1337508,"Effects of arsenite in astrocytes on neuronal signaling transduction Abstract: The main purpose of this study was to test the hypothesis that arsenite induces neurotoxicity via effects on astrocytes. Astrocytes were exposed to 0, 5 or 10?M arsenite in medium for 24h, and then astrocyte-conditioned medium (ACM) was collected after incubation with fresh medium for 6h. Primary neuron cultures were divided into four groups due to ACM, which were neurons without ACM exposure (group I) and neurons exposed to ACM from 0, 5 or 10?M arsenite treated astrocytes (group II-IV). Protein expression of N-methyl-d-aspartate receptors (NR1, NR2A, NR2B), calmodulin-dependent protein kinaseII (CaMKII) and adenylate cyclase (AC) in neurons were measured after incubation with ACM for 4, 8 or 12h. Morphological changes and synaptic formation were observed after a 72h-incubation with ACM. Compared to group II, synaptic formation and protein expression of NR2A, NR2B, CaMKII and AC in group III and IV were significantly suppressed. Moreover, synaptic formation and protein expression of CaMKII and AC in group II were significantly enhanced when compared with group I. Taken together, findings from this study suggested that arsenic in astrocytes might impair synaptic formation through disturbing astrocytic effects on neuronal signal transduction.",
Arsenic,1240311,"Trace metals alter DNA repair and histone modification pathways concurrently in mouse embryonic stem cells Abstract: Exposure to metals alters gene expression, changes transcription rates or interferes with DNA repair mechanisms. We tested a hypothesis to determine whether in vitro acute metal exposure, with or without recovery, alters epigenetic pathways in mouse embryonic stem (mES) cells. We measured cell viability, total and histone protein production, changes in gene expression for differentiation and DNA repair, and histone lysine mono-methylation (H3K27me1), in differentiated cells. Confluent differentiated cultures of mES cells were exposed to arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), lithium (Li), mercury (Hg), and nickel (Ni), for 1-h and 24-h, followed by a recovery period. The data demonstrate that maximum cell death occurred during the first few hours of exposure at 24-h IC50 concentrations for all metals. Prolonged in vitro exposure to metals at low concentrations also inhibited protein production and cell proliferation. Subsequently, we determined that metals alter cell differentiation (Oct-4 and egfr) and DNA repair mechanisms (Rad-18, Top-3a and Ogg-1). Interestingly, As, Cd, Hg, and Ni decreased cell proliferation to a greater extent than total histone protein production. Yet, at equivalent concentrations, As and Hg significantly decreased total histone protein production per cell compared to respective controls, suggesting suppression of repair or compensatory mechanisms involving histone pathways. And, acute exposure to As, Cd, Hg and Ni decreased H3K27me1 residue, when compared to control cells. Because activation of cellular differentiation, histone modification, and DNA repair are linked by common transcriptional pathways, and the data propose that metals alter these conduits, then it is reasonable to conclude that trace quantities of metals are capable of suppressing regulation of chromatin structure, cellular differentiation, and controlled cell proliferation in mES cells.",
Arsenic,628126,"Arsenic inhibition of telomerase transcription leads to genetic instability Abstract: Arsenic is effective in the treatment of acute promyelocytic leukemia. Paradoxically, it is also carcinogenic. In the process of elucidating a mechanism of arsenic resistance in a leukemia cell line, NB4, we discovered that arsenic exposure causes chromosomal abnormalities, with a preponderance of end-to-end fusions. These chromosomal end fusions suggested that telomerase activity may be inhibited by arsenic. We found that arsenic inhibits transcription of the hTERT gene, which encodes the reverse transcriptase subunit of human telomerase. This effect may in part be explained by decreased c-Myc and Sp1 transcription factor activities. Decreased telomerase activity leads to chromosomal end lesions, which promote either genomic instability and carcinogenesis or cancer cell death. These phenomena may explain the seemingly paradoxical carcinogenic and antitumor effects of arsenic.",
Arsenic,1026305,"Enhancements of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism and carcinogenic risk via NNK/arsenic interaction Abstract: Epidemiological studies indicated an enhancement of cigarette smoke-induced carcinogenicity, including hepatocellular carcinoma, by arsenic. We believe that arsenic will enhance the expression of hepatic CYP2A enzyme and NNK metabolism (a cigarette smoke component), thus its metabolites, and carcinogenic DNA adducts. Male ICR mice were exposed to NNK (0.5 mg/mouse) and sodium arsenite (0, 10, or 20 mg/kg) daily via gavaging for 10 days and their urine was collected at day 10 for NNK metabolite analysis. Liver samples were also obtained for CYP2A enzyme and DNA adducts evaluations. Both the cyp2a4/5 mRNA levels and the CYP2A enzyme activity were significantly elevated in arsenic-treated mice liver. Furthermore, urinary NNK metabolites in NNK/arsenic co-treated mice also increased compared to those treated with NNK alone. Concomitantly, DNA adducts (N(7)-methylguanine and O(6)-methylguanine) were significantly elevated in the livers of mice co-treated with NNK and arsenic. Our findings provide clear evidence that arsenic increased NNK metabolism by up-regulation of CYP2A expression and activity leading to an increased NNK metabolism and DNA adducts (N(7)-methylguanine and O(6)-methylguanine). These findings suggest that in the presence of arsenic, NNK could induce greater DNA adducts formation in hepatic tissues resulting in higher carcinogenic potential.",
Arsenic,2278953,"Identification of a Novel Membrane Transporter Mediating Resistance to Organic Arsenic in Campylobacter jejuni Abstract: Although bacterial mechanisms involved in the resistance to inorganic arsenic are well understood, the molecular basis for organic arsenic resistance has not been described. Campylobacter jejuni, a major food-borne pathogen causing gastroenteritis in humans, is highly prevalent in poultry and is reportedly resistant to the arsenic compound roxarsone (4-hydroxy-3-nitrobenzenearsonic acid), which has been used as a feed additive in the poultry industry for growth promotion. In this study, we report the identification of a novel membrane transporter (named ArsP) that contributes to organic arsenic resistance in Campylobacter. ArsP is predicted to be a membrane permease containing eight transmembrane helices, distinct from other known arsenic transporters. Analysis of multiple C. jejuni isolates from various animal species revealed that the presence of an intact arsP gene is associated with elevated resistance to roxarsone. In addition, inactivation of arsP in C. jejuni resulted in 4- and 8-fold reductions in the MICs of roxarsone and nitarsone, respectively, compared to that for the wild-type strain. Furthermore, cloning of arsP into a C. jejuni strain lacking a functional arsP gene led to 16- and 64-fold increases in the MICs of roxarsone and nitarsone, respectively. Neither mutation nor overexpression of arsP affected the MICs of inorganic arsenic, including arsenite and arsenate, in Campylobacter. Moreover, acquisition of arsP in NCTC 11168 led to accumulation of less roxarsone than the wild-type strain lacking arsP. Together, these results indicate that ArsP functions as an efflux transporter specific for extrusion of organic arsenic and contributes to the resistance to these compounds in C. jejuni.",
Arsenic,1019080,"Modulation of cell adhesion and viability of cultured murine bone marrow cells by arsenobetaine, a major organic arsenic compound in marine animals Abstract: 1. In this study, we investigated the biological effects of trimethyl (carboxymethyl) arsonium zwitterion, namely arsenobetaine (AsBe), which is a major organic arsenic compound in marine animals using murine bone marrow (BM) cells and compared them with those of an inorganic arsenical, sodium arsenite, in vitro. 2. Sodium arsenite showed strong cytotoxicity in BM cells, and its IC(50) was 6 microM. In contrast, AsBe significantly enhanced the viability of BM cells in a dose-dependent manner during a 72-h incubation; about a twofold increase in the viability of cells compared with that of control cells cultured with the medium alone was observed with a microM level of AsBe. 3. In morphological investigations, AsBe enhanced the numbers of large mature adherent cells, especially granulocytes, during a 72-h BM culture. When BM cells were cultured together with AsBe and a low dose (1 u ml(-1)) of recombinant murine granulocyte/macrophage colony-stimulating factor (rMu GM-CSF), significant additive-like increasing effects were observed on the numbers of both granulocytes and macrophages originated from BM cells. However, AsBe did not cause proliferation of BM cells at all as determined by colony-forming assay using a gelatinous medium. 4. These findings demonstrate the unique and potent biological effects in mammalian cells of AsBe, a major organic arsenic compound in various marine animals which are ingested daily as seafood in many countries.",
Arsenic,1033950,"Effects of chronic exposure to arsenate on the cardiovascular function of rats Abstract: Cardiovascular function was studied in anaesthetised male rats which received 50 micrograms/ml of arsenic (as sodium arsenate) in deionised drinking water for 320 days. High urinary excretion of arsenic was found at the end of treatment and the metal accumulated considerably in the kidneys and liver, which both presented slight alterations. No histopathological modifications were evident in other organs. Base line blood pressure, cardiac inotropism, and chronotropism and cardiovascular reactivity to noradrenaline, acetylcholine, angiotensin II, bradykinin, histamine, and serotonin did not differ in exposed or in control animals. In the exposed group, however, there was potentiation of the effects of vascular beta-adrenoceptor stimulation and a reduction in the vascular responsiveness to angiotensin I. Chronic arsenic exposure did not affect the baroreflex sensitivity but was able to induce sympathetic hyperactivity or hypersensitivity, or both, possibly associated with an antivagal action. Our results might help to explain the cardiovascular alterations seen in people chronically exposed to high concentrations of arsenic.",
Arsenic,1235468,"A comparison of hepatocyte cytotoxic mechanisms for chromate and arsenite Abstract: In the following, we have compared the cytotoxic mechanisms of the chromate CrO(4)(2-) and arsenite AsO(2)(-). Chromate (Cr (VI)) cytotoxicity was associated with reactive oxygen species (ROS) formation, lipid peroxidation and loss of mitochondrial membrane potential, which were prevented by catalase, antioxidants and ROS scavengers. Hepatocyte glutathione was also rapidly oxidized. Chromate reduction was inhibited in glutathione depleted hepatocytes, and glutathione depleted hepatocytes were also much more resistant to chromate induced cytotoxicity, ROS formation and lipid peroxidation. This suggests that chromate is reductively activated by glutathione. Chromate cytotoxicity also involved lysosomal injury and protease activation, which were prevented by lysosomotropic agents, endocytosis inhibitors, protease inhibitors and ROS scavengers. On the other hand, arsenite cytotoxicity was associated with much less oxidative stress, and lysosomal damage did not occur. However, arsenite cytotoxicity was also associated with loss of mitochondrial membrane potential, which in contrast to chromate cytotoxicity was inhibited by the ATP generators fructose, xylitol and glutamine. Arsenite induced cytotoxicity, mitochondrial membrane potential decline and also ROS formation were significantly increased by inactivating hepatocyte methionine synthase or hepatocyte methyl transferase. However, methyl donors such as betaine, methionine or folic acid prevented arsenite but not chromate cytotoxicity, and this suggests that arsenite is detoxified by reductive methylation. In conclusion, chromate induced cytotoxicity could be attributed to oxidative stress and lysosomal damage, whereas arsenite induced cytotoxicity could be attributed to mitochondrial toxicity and ATP depletion.",
Arsenic,2343528,"The impact of increased soil risk elements on carotenoid contents Abstract: A pot experiment was conducted to compare the responses of a non-transgenic tobacco plant (WT) and plants with genetically prolonged life-span (SAG) to risk elements of As, Cd and Zn. Plants were grown in control soil and in soil with higher levels of risk elements. The pigment contents were established by HPLC and chlorophyll fluorescence parameters were measured from slow kinetics after a 15 min dark period with the PAM fluorometer. Top (i.e. young) leaves of both WT and SAG plants were more sensitive to photoinhibition caused by these risk elements but plants showed acclimation to such elements in the bottom leaves. Plants differed in the participation of individual pigments of xanthophyll cycle: increased levels of risk elements seem to stimulate especially first (violaxanthin to antheraxanthin) and second (anhtheraxanthin to zeaxanthin) steps of the cycle in WT plants. In SAG plants, toxic elements caused an increase in the content, particularly of the initial compound of the cycle - violaxanthin.",
Arsenic,2088321,Migration of arsenic in multi-aquifer system of southern Bengal Basin: analysis via numerical modeling Abstract: ,
Arsenic,1344778,"Heavy metal concentrations in sultana-cultivation soils and sultana raisins from Manisa (Turkey) Abstract: This paper describes the concentrations of heavy metals in soils and in raisins (sultanas) cultivated upon the Gediz Plain (Manisa), western Turkey, which is cut by major roads from ?zmir to ?stanbul and ?zmir to Ankara. A total of 212 samples of surface soil and 82 raisin samples were analysed. Soil samples have nearly same mineralogy, quartz, calcite, magnetite, pseudo-rutile and clay minerals. Dolomite is seen especially in areas close to Neogene sediments. Clay minerals are mainly mica (illite–muscovite), chlorite/kaolinite, smectite and mixed layers (Sm-Il). The concentrations of 21 elements (Ba, Ni, Mo, Cu, Pb, Zn, Co, Mn, As, U, Sr, Cd, Sb, Bi, Cr, B, W, Hg, Sn, Li and organic C) were determined in the surface soils. The degree of element enrichment in soil can be measured in many ways, the most common of which are the geoaccumulation index (Igeo), enrichment factor and the pollution index. Arsenic and Sb showed the highest Igeo values, corresponding to Igeo classes 3–4. Hence, the area is characterised as “being heavily contaminated to polluted” by As and Sb. Arsenic contamination has been reported from all over world. Arsenic-related pollutants enter the groundwater system by gradually moving with the flow of groundwater from rains and irrigation. Gediz Plain forms the main groundwater supply of ?zmir city. The enrichment factor (EFarsenic) of the analysed soil samples is around 76, which corresponds to “extremely high enrichment”. The concentrations of 33 elements (Al, Sb, As, Ba, Be, Bi, B, Cd, Ca, Cr, Co, Cu, Fe, Pb, Li, Mg, Mn, Hg, Mo, Ni, K, Se, Ag, Na, Sr, Ta, Th, Sn, Ti, U, V, Zn and Zr) were determined in the raisin samples. The Pb and Cd contents of raisins are of great concern due to their toxicity. Pb contents ranged between 0.05 and 0.46 mg kg?1, and average Cd content was 0.04 mg kg?1. Only one sample contained high level of Cd, 0.23 mg kg?1. After cleaning the raisins, the heavy metal concentrations were low as in the European Community (EC) regulation No: 466/2001 for allowable levels of Pb (0.2 mg kg?1) and Cd (0.05 mg kg?1).",
Arsenic,1337745,"Arsenic extractability and uptake by velvetgrass Holcus lanatus and ryegrass Lolium perenne in variously treated soils polluted by tailing spills Abstract: Phytostabilization should be considered as an appropriate phytoremediation technique to restore the area affected by tailing spills in Zloty Stok, where arsenic ores were mined and processed for several centuries. The study aimed to compare the suitability of velvetgrass (Holcus lanatus L.) and ryegrass (Lolium perenne L.) for development of plant cover in that area. Various treatments commonly applied to support phytostabilization were examined. A pot experiment was carried out to assess the effects of soil amendment with phosphate (P), sewage sludge (SS) and iron salts (Fe) on arsenic extractability and its uptake by grass. Four kinds of soil material, containing 356-5350mgkg(-1) As, were examined. Velvetgrass proved to be more resistant than ryegrass to the toxicity of soil arsenic. Ammonium sulphate extractability of As in soils correlated well with As concentrations in the biomass of both grass species. In three of four tested soils, application of Fe failed to decrease As extractability and to reduce its concentrations in the aboveground parts of grasses. Application of P and SS resulted in increased As solubility in soils, but their effects on plant biomass and As uptake were ambiguous. SS had a strong beneficial influence on the growth of velvetgrass, while such an effect was not observed for ryegrass.",
Arsenic,1519136,"Vertical geochemical variations and arsenic mobilization in the shallow alluvial aquifers of the Chapai-Nawabganj District, northwestern Bangladesh: implication of siderite precipitation Abstract: ",
Arsenic,1031991,"Carcinogenesis as the result of the deficiency of some essential trace elements Abstract: &quot;Energetic&quot; biological trace elements [gallium (III), germanium (IV), silicon (silica), arsenic (V) and selenium (IV)] occurring in DNA of eukaryotic cells may improve the semiconductor properties of DNA and may influence the mechanisms that control genetic expression at the electronic level. Their roles are postulated as follows: (i) to maintain the level and direction of free sliding electrons in DNA, (ii) to modulate the electron conductivity and hole conductivity of DNA. This specific electronic nature of DNA take the form of magnetic pigeonholes in which an electric pulse is (0), or is not (1) stored as an area of local magnetisation. These types of conductivity occurring in different parts of DNA of different cells could participate in the switch on and switch off of genetic information in gene expression. This model may help to elucidate the mechanism of action of these naturally occurring antitumor agents and may help in understanding the role of trace elements in charge transport of DNA and in carcinogenesis.",
Arsenic,2343497,"Exploring the diversity of arsenic resistance genes from acid mine drainage microorganisms Abstract: The microbial communities from the Tinto River, a natural acid mine drainage (AMD) environment, were explored to search for novel genes involved in arsenic resistance using a functional metagenomic approach. Seven As(V)-resistance clones were selected and analyzed to find the genes responsible for this phenotype. Insights about their possible mechanisms of resistance were obtained from sequence similarities and cellular arsenic concentration. A total of 19 individual ORFs were analyzed and each one was individually cloned and assayed for its ability to confer arsenic resistance in E. coli cells. A total of 13 functionally active genes involved in arsenic resistance were identified and they could be classified into different global processes: transport, stress response, DNA damage repair, phospholipids biosynthesis, amino acid biosynthesis and RNA modifying enzymes. Most genes (eleven) encode proteins not previously related to heavy metal resistance or hypothetical or unknown proteins. On the other hand, two genes were previously related to heavy metal resistance in microorganisms. In addition, the ClpB chaperone and the RNA modifying enzymes retrieved in this work were shown to increase the cell survival under different stress conditions (heat shock, acid pH and UV-radiation). Thus, these results reveal novel insights about unidentified mechanisms of arsenic resistance.",
Arsenic,627476,"Arsenic Exposure and Health Effects III Reproductive and developmental effects associated with chronic arsenic exposure Abstract: Chronic exposure to inorganic arsenic is known to cause cancer and non-cancer health effects in humans. The evidence from animal studies clearly shows that arsenic is teratogenic, and the findings of limited human studies suggest that inorganic arsenic may be associated with several reproductive/developmental outcomes, including increased rates of spontaneous abortion, low birth weight, congenital malformations, pre-eclampsia and infant mortality. The city of Antofagasta, located in northern Chile, has a history of high arsenic exposure in drinking water. Due to changes in the sources of water, there were considerably high arsenic levels in the public drinking water supply from 1958 to 1970 (over 800 ug/L), which decreased gradually to the current concentrations close to 50 ug/L. A number of studies have reported various health effects associated with the high exposure period, including skin alterations typically linked to arsenic exposure and increases in bladder and lung cancer. We conducted an ecologic study of infant mortality rates in Chile from 1950 to 1996, comparing Antofagasta to low arsenic exposure areas. Temporal and cross-regional comparisons showed a general steady decline over time in late fetal, neonatal and post-neonatal mortality rates for all locations, consistent with improvements in standard of living and health care. However, comparatively high rates were observed in Antofagasta for the three outcomes studied during the 12-year period of highest arsenic exposure, compared to Santiago and Valparaiso, two locations used as reference groups. While not definitive, these findings support a role for arsenic in the observed increases in mortality rates. Given the worldwide public health concern for arsenic effects, more population studies are needed in the area of human reproductive and developmental effects.",
Arsenic,1346097,Kinetic Modeling of the Alkaline Decomposition of Potassium Arsenojarosite Abstract: ,
Arsenic,1508599,"As(III) and As(V) sorption on iron-modified non-pyrolyzed and pyrolyzed biomass from Petroselinum crispum (parsley) Abstract: The sorption of As(III) and As(V) from aqueous solutions onto iron-modified Petroselinum crispum (PCFe) and iron-modified carbonaceous material from the pyrolysis of P. crispum (PCTTFe) was investigated. The modified sorbents were characterized with scanning electron microscopy. The sorbent elemental composition was determined with energy-dispersive X-ray spectroscopy (EDS). The principal functional groups from the sorbents were determined with FT-IR. The specific surfaces and points of zero charge (pzc) of the materials were also determined. As(III) and As(V) sorption onto the modified sorbents were performed in a batch system. After the sorption process, the As content in the liquid and solid phases was determined with atomic absorption and neutron activation analyses, respectively. After the arsenic sorption processes, the desorption of Fe from PCFe and PCTTFe was verified with atomic absorption spectrometry. The morphology of PC changed after iron modification. The specific area and pzc differed significantly between the iron-modified non-pyrolyzed and pyrolyzed P. crispum. The kinetics of the arsenite and arsenate sorption processes were described with a pseudo-second-order model. The Langmuir-Freundlich model provided the isotherms with the best fit. Less than 0.02% of the Fe was desorbed from the PCFe and PCTTFe after the As(III) and As(V) sorption processes.",
Arsenic,1704074,Preparation and evaluation of Zr-beta-FeOOH for efficient arsenic removal Abstract: ,
Arsenic,1936079,"Arsenic toxicity induced endothelial dysfunction and dementia: Pharmacological interdiction by histone deacetylase and inducible nitric oxide synthase inhibitors Abstract: Arsenic toxicity has been reported to damage all the major organs including the brain and vasculature. Dementia including Alzheimer's disease (AD) and vascular dementia (VaD) are posing greater risk to the world population as it is now increasing at a faster rate. We have investigated the role of sodium butyrate, a selective histone deacetylase (HDAC) inhibitor and aminoguanidine, a selective inducible nitric oxide synthase (iNOS) inhibitor in pharmacological interdiction of arsenic toxicity induced vascular endothelial dysfunction and dementia in rats. Arsenic toxicity was done by administering arsenic drinking water to rats. Morris water-maze (MWM) test was used for assessment of learning and memory. Endothelial function was assessed using student physiograph. Oxidative stress (aortic superoxide anion, serum and brain thiobarbituric acid reactive species, brain glutathione) and nitric oxide levels (serum nitrite/nitrate) were also measured. Arsenic treated rats have shown impairment of endothelial function, learning and memory, reduction in serum nitrite/nitrate & brain GSH levels along with increase in serum & brain TBARS. Sodium butyrate as well as aminoguanidine significantly convalesce arsenic induced impairment of learning, memory, endothelial function, and alterations in various biochemical parameters. It may be concluded that arsenic induces endothelial dysfunction and dementia, whereas, sodium butyrate, a HDAC inhibitor as well as aminoguanidine, a selective iNOS inhibitor may be considered as potential agents for the management of arsenic induced endothelial dysfunction and dementia.",
Arsenic,2343504,"Trace-Element Interactions in Rook Corvus frugilegus Eggshells Along an Urbanisation Gradient Abstract: Concentrations of seven trace elements [arsenic (As), chromium (Cr), nickel (Ni), lead (Pb), copper (Cu), zinc (Zn), and cadmium (Cd)] in the eggshells of Rooks Corvus frugilegus, a focal bird species of Eurasian agricultural environments, are increased above background levels and exceed levels of toxicological concern. The concentrations of Cr, Ni, Pb, Cu, and Zn are greater in eggshells from urban rookeries (large cities) compared with rural areas (small towns and villages) suggesting an urbanisation gradient effect among eggs laid by females. In the present study, the investigators assessed whether the pattern of relationships among the seven trace elements in eggshells change along an urbanisation/pollution gradient. Surprisingly, we found that eggshells with the greatest contaminant burden, i.e., from urban rookeries, showed far fewer significant relationships (n = 4) than eggshells from villages (n = 10), small towns (n = 6), or rural areas (n = 8). In most cases, the relationships were positive. As was an exception: Its concentration was negatively correlated with Ni and Cd levels in eggshells from small town rookeries (where As levels were the highest), whereas eggshells from villages (with a lower As level) showed positive relationships between As and Cd. Our findings suggest that at low to intermediate levels, interactions between the trace elements in Rook eggshells are of a synergistic character and appear to operate as parallel coaccumulation. A habitat-specific excess of some elements (primarily Cr, Ni, Cu, As) suggests their more competitively selective sequestration.",
Arsenic,1797756,"Biostabilization enhancement of heavy metals during the vermiremediation of sewage sludge with passivant Abstract: The present study revealed the effects of fly ash (FA) and phosphoric rock (PR) on stabilization of sewage sludge (SS) after vermicomposting for 60 days. The earthworms in all vermibeds showed significant increases in tissue metal; however, the bioconcentration factors (BCFs) of all investigated metals (except Zn) differed among treatments. Additionally, significant differences were observed in the final system weight and SS+Passivant weight reduction among treatments, but not in the percentage reduction of total system weight and organic matter (OM). pH decreased from the initial levels, eventually reaching neutrality. Significantly greater earthworm heavy metals content, growth and reproduction rates and BCFs were observed, while a decreased percentage of total heavy metals concentration and a proportional decrease of extractable metals (except Cu and Zn) were observed in treatments mixed with FA and PR. Furthermore, significant linear correlations between BCFs and a reduction in percentage concentration of total metals (Cu, Pb, Cd and As) were shown, as well as BCF-Cu and relative proportional changes in extractable Cu. These results indicate that vermicomposting with proportions of FA and PR is better for stabilization and remediation of SS in a short period of time.",
Arsenic,1936129,"In situ analysis of oxygen consumption and diffusive transport in high-temperature acidic iron-oxide microbial mats Abstract: The role of dissolved oxygen as a principal electron acceptor for microbial metabolism was investigated within Fe(III)-oxide microbial mats that form in acidic geothermal springs of Yellowstone National Park (USA). Specific goals of the study were to measure and model dissolved oxygen profiles within high-temperature (65–75°C) acidic (pH?=?2.7–3.8) Fe(III)-oxide microbial mats, and correlate the abundance of aerobic, iron-oxidizing Metallosphaera yellowstonensis organisms and mRNA gene expression levels to Fe(II)-oxidizing habitats shown to consume oxygen. In situ oxygen microprofiles were obtained perpendicular to the direction of convective flow across the aqueous phase/Fe(III)-oxide microbial mat interface using oxygen microsensors. Dissolved oxygen concentrations dropped from ??50–60??M in the bulk-fluid/mat surface to below detection (<?0.3??M) at a depth of ??700??m (??10% of the total mat depth). Net areal oxygen fluxes into the microbial mats were estimated to range from 1.4–1.6?×?10?4??mol?cm?2?s?1. Dimensionless parameters were used to model dissolved oxygen profiles and establish that mass transfer rates limit the oxygen consumption. A zone of higher dissolved oxygen at the mat surface promotes Fe(III)-oxide biomineralization, which was supported using molecular analysis of Metallosphaera yellowstonensis 16S rRNA gene copy numbers and mRNA expression of haem Cu oxidases (FoxA) associated with Fe(II)-oxidation.",
Arsenic,1019241,"Biliary and urinary excretion of inorganic arsenic: monomethylarsonous acid as a major biliary metabolite in rats Abstract: In rats exposed to arsenite (AsIII) or arsenate (AsV), the biliary excretion of arsenic depends completely on availability of hepatic glutathione, suggesting that both AsIII and AsV are transported into bile in thiol-reactive trivalent forms (Gyurasics et al. [1991], Biochem. Pharmacol. 42, 465-468). To test this hypothesis, the bile and urine of bile duct-cannulated rats injected with AsIII or AsV (50 micromol/kg, iv) were collected periodically for 2 h and analyzed for arsenic metabolites by HPLC-hydride generation-atomic fluorescence spectrometry. Arsenic was excreted predominantly into bile in AsIII-injected rats, but the urine was the main route of excretion in AsV-exposed rats. Injected AsIII was excreted in urine practically unchanged, whereas both AsV and AsIII appeared in urine after administration of AsV. Irrespective of the arsenical administered, the bile contained 2 main arsenic species, namely AsIII and a hitherto unidentified metabolite. Formation of this metabolite could be prevented by pretreatment of the rats with the methylation inhibitor periodate-oxidized adenosine, indicating that it is a methylated arsenic compound. This metabolite could be converted in vitro into monomethylarsonic acid (MMAsV) by oxidation, whereas synthetic MMAsV could be converted into the unknown metabolite by reduction. Consequently, this biliary metabolite of both AsIII and AsV is monomethylarsonous acid (MMAsIII), a long-hypothesized, but never identified, intermediate in the biotransformation of AsIII and AsV. Although MMAsIII is thought to be formed from an oxidized precursor, rats injected with MMAsV did not excrete MMAsIII. In summary, the inorganic arsenicals investigated are transported into bile exclusively in trivalent forms, namely as AsIII and MMAsIII, but are excreted in urine in both tri- and pentavalent forms. Identification of MMAsIII is signified by the fact that this metabolite is more toxic than AsIII and AsV and thus formation of MMAsIII represents toxification of inorganic arsenic.",
Arsenic,1017992,"Bioavailability of arsenic in soil: pilot study results and design considerations Abstract: Bioavailability of arsenic (As) from ingested soil is estimated in a two-period experimental study involving 11 subjects/period. In the first period, a 7-day mass-balance study measured As in food/beverages, urine, and stool to estimate bioavailability of As in food and beverages. Food/beverage As bioavailability (percentage ingested that is not in stool samples) is estimated as 91.0% with a 95% confidence interval given by (84.1%, 97.9%). In the second 7-day study period, subjects were placed on an As suppression diet. In the evening of day 2, each subject ingested a capsule containing 0.63 g of soil, including approximately 111.7 µg of soil-As. The bioavailability estimate of As from food and beverage ingestion during the first 2 days of the second period was 89.7%. Bioavailability of soil-As was estimated over the 5-day period following capsule ingestion, accounting for estimated bioavailability of food/beverage As. Assuming analytic recovery rates of As from combined soil and food/beverage samples are equal, soil-As bioavailability is estimated as 48.7% (95% CI [36.2%, 61.3%]). Relative to bioavailability of As from food/beverage sources, soil-As is estimated to be 54.3% (95% CI [40.3%, 68.4%]) as bioavailable.",
Arsenic,1797746,"Irrigation of three wetland species and a hyperaccumlating fern with arsenic-laden solutions: observations of growth, arsenic uptake, nutrient status, and chlorophyll content Abstract: Engineered wetlands can be an integral part of a treatment strategy for remediating arsenic-contaminated wastewater, wherein, As is removed by adsorption to soil particles, chemical transformation, precipitation, or accumulation by plants. The remediation process could be optimized by choosing plant species that take up As throughout the seasonal growing period. This report details experiments that utilize wetland plant species native to Ohio (Carex stricta, Pycnanthemum virginianum, and Spartina pectinata) that exhibit seasonally related maximal growth rates, plus one hyperaccumulating fern (Pteris vittata) that was used to compare arsenic tolerance. All plants were irrigated with control or As-laden nutrient solutions (either 0, 1.5, or 25 mg As L(-1)) for 52 d. Biomass, nutrient content, and chlorophyll content were compared between plants treated and control plants (n = 5). At the higher concentration of arsenic (25 mg L(-1)), plant biomass, leaf area, and total chlorophyll were all lower than values in control plants. A tolerance index, based on total plant biomass at the end of the experiment, indicated C. stricta (0.99) and S. pectinata (0.84) were more tolerant than the other plant species when irrigated with 1.5 mg As L(-1). These plant species can be considered as candidates for engineered wetlands.",
Arsenic,2064135,"Arsenic accumulating bacteria isolated from soil for possible application in bioremediation Abstract: Twenty six arsenic (As) resistant bacterial strains were isolated from As contaminated paddy soil of West Bengal, India. Among them, 10 isolates exhibited higher As resistance capacity and could grow in concentration of 12000 mg l­1 of arsenate (AsV) and 2000 mg l­1 of arsenite (AsIII) in growing medium. Maximum growth was observed at 1000 mg l­1 and 100 mg l­1 in case of AsV and AsIII respectively. Results of incubation study carried out in basal salt minimal media (BSMY) containing 25 mg l­1 of AsV and AsIII separately showed that the isolates could accumulate 1.03 ­ 6.41 mg L­1 of AsV and 2.0 ­ 7.6 mg l­1 of AsIII from the media. The bacterial isolate AGH­21 showed highest As accumulating capacity both for AsV (25.64%) and AsIII (30.4%) under laboratory conditions. The isolates AGH­21 (NCBI accession no: HQ834295) showed highest sequence similarity (98%) with Bacillus sp. and could be used as a potential bioremediator in future to combat with arsenic toxicity.",
Arsenic,2088501,"Smokers' and Nonsmokers' Beliefs About Harmful Tobacco Constituents: Implications for FDA Communication Efforts Abstract: Introduction: Legislation requires the U.S. Food and Drug Administration (FDA) to release information to the public about harmful constituents in tobacco and tobacco smoke. To inform these efforts, we sought to better understand how smokers and nonsmokers think about tobacco constituents.Methods: In October 2012, 300U.S. adults aged 18-66 completed a cross-sectional Internet survey. The questions focused on 20 harmful tobacco constituents that FDA has prioritized for communicating with the public.Results: Most participants had heard of 7 tobacco constituents (ammonia, arsenic, benzene, cadmium, carbon monoxide, formaldehyde, and nicotine), but few participants had heard of the others (e.g., acrolein). Few participants correctly understood that many constituents were naturally present in tobacco. Substances that companies add to cigarette tobacco discouraged people from wanting to smoke more than substances that naturally occur in cigarette smoke (p &lt; .001). Ammonia, arsenic, carbon monoxide, and formaldehyde being in cigarettes elicited the most discouragement from smoking. Constituents elicited greater discouragement from wanting to smoke if respondents were nonsmokers (? = -.34, p &lt; .05), had negative images of smokers (i.e., negative smoker prototypes; ? = .19, p &lt; .05), believed constituents are added to tobacco (? = .14, p &lt; .05), or were older (? = .16, p &lt; .05).Conclusions: Our study found low awareness of most tobacco constituents, with greater concern elicited by additives. Efforts to communicate health risks of tobacco constituents should consider focusing on ones that elicited the most discouragement from smoking.",
Arsenic,2279341,"The occurrence of heavy metals in irrigated and non-irrigated arable soils, NW Albania Abstract: The study analysed the content of heavy metals in surface soil and sediment samples from the Bregu i Matit Plain in NW Albania in relation to irrigation in order to evaluate the soil pollution and the potential risk to human health. Evaluation of soil pollution was performed using the enrichment factor and geo-accumulation index. Contents of cadmium, chromium and nickel of irrigated soils were significantly higher than those of non-irrigated soil, while contents of lead (in three of the irrigated locations), zinc and arsenic (in one of the irrigated locations) were significantly lower. Correlation analysis (CA) and principal component analysis (PCA) indicated that the primary source of the first three metals was irrigation, and the last three metals were originated from other anthropic sources, like the use of chemicals, etc. Enrichment factor (E f) calculation showed that irrigated soils were most enriched in cadmium, chromium, copper and nickel. Index of geo-accumulation (I geo) revealed that arable soils of Bregu i Matit are unpolluted to moderately polluted with cadmium, chromium, copper and zinc and moderately to strongly polluted with nickel and arsenic. The presence of heavy metals in the studied soils indicates a potential risk of transfer of these elements in the food chain. Therefore, further studies on the speciation of heavy metals in the studied soils in order to evaluate their mobility are needed.",
Arsenic,379298,"Exposure to Metal-rich Particulate Matter Modifies the Expression of Candidate MicroRNAs in Peripheral Blood Leukocytes Abstract: BACKGROUND: Altered patterns of gene expression mediate the effects of particulate matter (PM) on human health, but mechanisms through which PM modifies gene expression are largely undetermined. MicroRNAs are highly conserved, non-coding small RNAs that regulate the expression of broad gene networks at the post-transcriptional level. OBJECTIVES: We evaluated the effects of exposure to PM and PM metal components on candidate miRNAs (miR-222, miR-21 and miR-146a) related with oxidative stress and inflammatory processes in 63 workers of an electric-furnace steel plant. METHODS: We measured miR-222, miR-21 and miR-146a expression in blood leukocyte RNA on the first day of a workweek (baseline) and after three days of work (post-exposure). Relative expression of microRNAs was measured by real-time PCR. We measured blood oxidative stress (8-hydroxyguanine) and estimated individual exposures to PM1, PM10, coarse particles and PM metal components (chromium, lead, cadmium, arsenic, nickel, manganese) between the baseline and post-exposure measurements. RESULTS: miR-222 and miR-21 expression was significantly increased in post-exposure samples (baseline=0.68+/-3.41, post-exposure=2.16+/-2.25; p=0.002 for miR-222; baseline=4.10+/-3.04, post-exposure=4.66+/-2.63,; p=0.05 for miR-21). In post-exposure samples, miR-222 expression was positively correlated with lead exposure (beta=0.41, p=0.02), while miR-21 expression was associated with blood 8-hydroxyguanine (beta=0.11, p=0.03), but not with individual PM or metals. Post-exposure expression of miR-146a was not significantly different from baseline (baseline=0.61+/-2.42, post-exposure=1.90+/-3.94; p=0.19), but it was negatively correlated with exposure to lead (beta=-0.51, p=0.011) and cadmium (beta=-0.42, p=0.04). CONCLUSIONS: Changes in miRNA expression may represent a novel mechanism mediating responses to PM and its metal components.",
Arsenic,1250971,"Desulfohalophilus alkaliarsenatis gen. nov., sp. nov., an extremely halophilic sulfate- and arsenate-respiring bacterium from Searles Lake, California Abstract: A haloalkaliphilic sulfate-respiring bacterium, strain SLSR-1, was isolated from a lactate-fed stable enrichment culture originally obtained from the extreme environment of Searles Lake, California. The isolate proved capable of growth via sulfate-reduction over a broad range of salinities (125-330 g/L), although growth was slowest at salt-saturation. Strain SLSR-1 was also capable of growth via dissimilatory arsenate-reduction and displayed an even broader range of salinity tolerance (50-330 g/L) when grown under these conditions. Strain SLSR-1 could also grow via dissimilatory nitrate reduction to ammonia. Growth experiments in the presence of high borate concentrations indicated a greater sensitivity of sulfate-reduction than arsenate-respiration to this naturally abundant anion in Searles Lake. Strain SLSR-1 contained genes involved in both sulfate-reduction (dsrAB) and arsenate respiration (arrA). Amplicons of 16S rRNA gene sequences obtained from DNA extracted from Searles Lake sediment revealed the presence of close relatives of strain SLSR-1 as part of the flora of this ecosystem despite the fact that sulfate-reduction activity could not be detected in situ. We conclude that strain SLSR-1 can only achieve growth via arsenate-reduction under the current chemical conditions prevalent at Searles Lake. Strain SLSR-1 is a deltaproteobacterium in the family Desulfohalobiacea of anaerobic, haloalkaliphilic bacteria, for which we propose the name Desulfohalophilus alkaliarsenatis gen. nov., sp. nov.",
Arsenic,1794747,Oxidative stress: the mitochondria-dependent and mitochondria-independent pathways of apoptosis Abstract: ,
Arsenic,657847,"Chronic exposure to arsenic sensitizes CD3+ and CD56+ human cells to sodium arsenite-mediated apoptosis Abstract: Despite the relevance of immune responses in cancer development, little is known about arsenite-induced apoptosis on different immune effectors cells. In this work, we determined the effect of in vitro exposure to sodium arsenite on apoptosis rates of blood lymphocytes, monocytes and NK cells. Blood was obtained from six healthy non-exposed donors, and also from a woman chronically exposed to arsenic. The results indicated that in vitro exposure of mononuclear cells (MNC) from non-exposed donors to sodium arsenite showed no increase in apoptosis as compared to non-treated cells. In contrast, cells obtained from the exposed-donor showed a significant increase in apoptosis after the treatment with sodium arsenite as compared to non-treated cells. This effect was observed in CD3+ and CD56+ but not in CD14+ cells. In addition, we found a preexisting high basal level of apoptosis in MNC from the exposed-donor. These results indicate that chronic exposure to arsenic increases the sensitivity of immune cells to in vitro sodium arsenite-mediated apoptosis.",
Arsenic,1354699,"ON POSSIBLE ORIGIN OF BACKGROUND CONTENTS OF HEAVY METALS AND METALLOIDS IN THE SUBSURFACE PENNSYLVANIAN TESENY METASANDSTONES, SW HUNGARY Abstract: ",
Arsenic,2298714,"Rapid on-site separation of as(III) and as(V) in waters using a disposable thiol-modified sand cartridge Abstract: The rapid redox transformation of arsenic (As) species in waters presents a great environmental challenge in accurate determination of its concentration and toxicity. The motivation for our study is therefore to develop a method for rapid on-site separation of As(V) and As(III) in various aqueous matrices. We synthesized a thiol-modified sand (T-sand), which selectively removed As(III) but did not adsorb As(V). The novel application of this T-sand in a disposable cartridge could successfully separate As(V) (37-970?µg?L(-1) ) and As(III) (N.D.-488?µg?L(-1) ) in 23 groundwater samples collected in areas with naturally occurring As. The As speciation results determined with T-sand separation in the field were consistent with those obtained using HPLC-AFS. Furthermore, the T-sand cartridge was applicable in a wide variety of matrices including groundwater, leachants of the toxicity characteristic leaching procedure, and extracts from the California waste extraction test, sequential extraction test, and in vitro gastrointestinal extraction. This easy-to-use separation method is especially suitable for routine field monitoring of As speciation. Environ Toxicol Chem © 2014 SETAC.",
Arsenic,2278546,"Is arsenic biotransformation a detoxification mechanism for microorganisms? Abstract: Arsenic (As) is extremely toxic to living organisms at high concentration. In aquatic systems, As exists in different chemical forms. The two major inorganic As (iAs) species are As(V), which is thermodynamically stable in oxic waters, and As(III), which is predominant in anoxic conditions. Photosynthetic microorganisms (e.g., phytoplankton and cyanobacteria) take up As(V), biotransform it to As(III), then biomethylate it to methylarsenic (MetAs) forms. Although As(III) is more toxic than As(V), As(III) is much more easily excreted from the cells than As(V). Therefore, majority of researchers consider the reduction of As(V) to As(III) as a detoxification process. The biomethylation process results in the conversion of toxic iAs to the less toxic pentavalent MetAs forms (monomethylarsonate; MMA(V), dimethylarsonate; DMA(V), and trimethylarsenic oxide; TMAO(V)) and trimethylarsine (TMAO(III)). However, biomethylation by microorganisms also produces monomethylarsenite (MMA(III)) and dimethylarsenite (DMA(III)), which are more toxic than iAs, as a result of biomethylation by the microorganisms, demonstrates the need to reconsider to what extent As biomethylation contributes to a detoxification process. In this review, we focused on the discussion of whether the biotransformation of As species in microorganisms is really a detoxification process with recent data.",
Arsenic,627367,"HPLC-ICP-MS speciation analysis of arsenic in urine of Japanese subjects without occupational exposure Abstract: The toxicity and carcinogenicity of arsenic depend on its species. Individuals living in Japan consume much seafood that contains high levels of organoarsenics. Speciation analysis of urinary arsenic is required to clarify the health risks of arsenic intake. There has been no report of urinary arsenic analysis in Japan using high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). We performed speciation analysis of urinary arsenic for 210 Japanese male subjects without occupational exposure using HPLC-ICP-MS. The median values of urinary arsenics were as follows: sodium arsenite (AsIII), 3.5; sodium arsenate (AsV), 0.1; monomethylarsonic acid (MMA), 3.1; dimethylarsinic acid (DMA), 42.6; arsenobetaine (AsBe), 61.3; arsenocholine, trimethylarsine oxide, and unidentified arsenics (others), 5.2; and total arsenic (total As), 141.3 microgAs/l. The median creatinine-adjusted values were as follows: AsIII, 3.0; AsV, 0.1; MMA, 2.6; DMA, 35.9; AsBe, 52.1; others 3.5; and total As, 114.9 microgAs/g creatinine. Our findings indicate that DMA and AsBe levels in Japan are much higher than those found in Italian and American studies. It appears that the high levels of DMA and AsBe observed in Japan may be due in part to seafood intake. ACGIH and DFG set the BEI and BAT values for occupational arsenic exposure as 35 microgAs/l and 50 microgAs/l, respectively, using the sum of inorganic arsenic (iAs), MMA, and DMA. In the general Japanese population, the sums of these were above 50 microgAs/l in 115 (55%) samples. We therefore recommend excluding DMA concentration in monitoring of iAs exposure.",
Arsenic,1347282,"Polychromic structures and pigments in Guangyuan Thousand-Buddha Grotto of the Tang Dynasty (China) Abstract: This paper presents a multi-analytical study of the polychromy in the Guangyuan Thousand-Buddha Grotto. Samples taken from 15 locations in No. 512 and No. 689 caves are prepared as cross-sections for the analysis by optical microscopy (OM) and scanning electron microscopy coupled with backscattered electron imaging (SEM-BSE). The cross section analysis indicates that some paintings were repainted in the past. The chemical composition of each painting layer is obtained by scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX). The main pigments for 15 samples including green, red, blue, white and black paint layers, are identified by the combination of polarized light microscopy (PLM), Fourier Transform infrared spectrum (FT-IR), Raman spectroscopy (RS) and X-ray diffraction (XRD) analysis. The integrated analytical results reveal that the green pigments are malachite and atacamite; the red color is attributed to minium, hematite and cinnabar; the blue pigments are lazurite and organic blue materials; the white color is ascribed to anglesite and gypsum; and the black surface of polychrome is the accumulation of longtime smudging by folk burning incense in the devotional practice or the soot deposition resulting from burning bonfires in the caves. Some arsenic-containing pigment is detected in the green samples. This case study also demonstrates the advantages and the limitations of every analytical technique for the pigment identification, confirming the necessity of the integrated analytical techniques approach. The present results are not only useful to assist in the authenticity of the used pigment materials and history of the polychromic in the past, but also aimed at guiding the conservation scientists in taking into account materials and methods utilized in the past.",
Arsenic,1247916,"Comparison of expression patterns of keratin 6, 7, 16, 17, and 19 within multiple independent isolates of As(+3)- and Cd (+2)-induced bladder cancer : keratin 6, 7, 16, 17, and 19 in bladder cancer Abstract: This laboratory has generated a series of seven cadmium (Cd(+2))- and six arsenite (As(+3))-transformed urothelial cancer cell lines by exposure of parental UROtsa cells to each agent under similar conditions of exposure. In this study, the seven Cd(+2)-transformed cell lines were characterized for the expression of keratin 6, 16, and 17 while the six As(+3) cell lines were assessed for the expression of keratin 7 and 19. The results showed that the series of Cd(+2)-transformed cell lines and their respective transplants all had expression of keratin 6, 16, and 17 mRNA and protein. The expression of keratin 6, 16, and 17 was also correlated with areas of the urothelial tumor cells that had undergone squamous differentiation. The results also showed that four of the six As(+3)-transformed cell lines had expression of keratin 7 and 19 mRNA and protein and produced subcutaneous tumors with intense focal staining for keratin 7 and 19. The other two As(+3)-transformed cell lines had very low expression of keratin 7 mRNA and protein and produced subcutaneous tumors having no immunoreactivity for keratin 7; although keratin 19 expression was still present. The peritoneal tumors produced by one of these two cell lines regained expression of keratin 7 protein. The present results, coupled with previous studies, indicate that malignant transformation of UROtsa cells by Cd(+2) or As(+3) produce similar patterns of keratin 6, 7, 16, 17, and 19 in the resulting series of cell lines and their respective tumors.",
Arsenic,1255642,"Theoretical Study of Hyperfine Interactions in Small Arsenic-Containing Radicals Abstract: Various density functional theory (DFT) and ab initio MP2 and CCSD methods were employed in calculations of arsenic isotropic and anisotropic hyperfine parameters in three small radicals, AsH2, AsO2, and H2AsO. Convergent basis sets for these calculations were specially derived starting from Dunning's correlation-consistent sets. DFT methods proved to be particularly appropriate choice, since the results obtained with the suitable functionals are in accordance with the available experimental values. Additionally, mechanisms of hyperfine couplings were investigated by examining individual orbital contributions to spin density. Spin polarization mechanism in AsH2 was studied by evaluating one- and two-electron integrals in spin-restricted and unrestricted case. Apart from non-relativistic, scalar-relativistic Douglas-Kroll-Hess DFT calculations were performed in order to examine relativistic impacts on spin density distribution.",
Arsenic,2278808,"Naturally dissolved arsenic concentrations in the Alpine/Mediterranean Var River watershed (France) Abstract: A detailed study on arsenic (As) in rocks and water from the Var River watershed was undertaken aiming at identifying (i) the origin and the distribution of As in this typical Alpine/Mediterranean basin, and (ii) As input into the Mediterranean Sea. Dissolved As concentrations in the Var River range from 0.1 to 4.5 ?g?L(-1), due to high hydrological variability and the draining through different geological formations. In the upper part of the Var drainage basin, in the Tinée and the Vésubie valleys, high levels of dissolved As concentrations occur (up to 263 ?g?L(-1)). The two main sources of As in rocks are the Hercynian metamorphic rocks and the Permian argilites. Highly heterogeneous distribution of As in waters draining through metamorphic rocks is probably related to ore deposits containing arsenopyrite. As, U, W and Mo concentrations in water and rocks correspond to the formation of As-rich ore deposits around Argentera granite by hydrothermal fluids deposited at the end of the Hercynian chain formation, which occurred about 300 My ago. In 2009, weekly monitoring was performed on the Var River (15 km upstream of the mouth), highlighting an average dissolved As concentration (<0.45 ?m) of 2.7 ± 0.9 ?g?L(-1), which is significantly higher than the world-average baseline for river water (0.83 ?g?L(-1)). Taking the average annual discharge (49.4 m(3)?s(-1)) into account and the As levels in the dissolved phase and in deposits of the Var River, dissolved As input into the Mediterranean Sea would be 4. 2± 1.4 tons?year(-1) which represents 59% of the total As flux. This study also reveals a probable non-conservative As behaviour, i.e., possible transfer between aqueous and solid phases, during the mixing of the Var River with a tributary.",
Arsenic,628340,"Reduction in kidney cancer mortality following installation of a tap water supply system in an arsenic-endemic area of Taiwan Abstract: Arsenic is the major risk factor for blackfoot disease, a peripheral vascular disease that has been endemic to the southwest coast of Taiwan for more than 50 yr because of the consumption of local artesian well water containing high levels of arsenic. Long-term arsenic exposure has been associated with kidney cancer mortality in a dose-response relationship. In the early 1960s, a tap water supply system was implemented in the blackfoot-endemic areas. After the mid-1970s, artesian well water was no longer used for drinking or cooking in the region. The authors examined whether kidney cancer mortality decreased after the elimination of arsenic exposure from artesian well water. Standardized mortality ratios for kidney cancer were calculated for the blackfoot-endemic area for the years 1971-2000. Study results showed that mortality from kidney cancer declined gradually during this time; therefore, the association of arsenic exposure with kidney cancer mortality was likely causal.",
Arsenic,2278385,"Improved sustainability of water supply options in areas with arsenic-impacted groundwater Abstract: The supply of water for rural populations in developing countries continues to present enormous problems, particularly where there is arsenic contamination in the groundwater, as exists over significant parts of Bangladesh. In response, improvements in the sustainability of water supplies are feasible through the use of a combination of water sources wherein rainwater harvesting is employed for a portion of the year. This can potentially reduce the duration of the year during which arsenic-contaminated groundwater is utilized. As demonstrated, a rainwater cistern volume of 0.5 m(3) in the Jessore district area of Bangladesh can provide rainwater for periods averaging 266 days of the year, which allows groundwater at 184 mu g/L arsenic to be used as a water supply for the remainder of the year. This dual supply approach provides the body burden equivalent to the interim drinking water guideline of arsenic concentration of 50 mu g/L for 365 days of the year (assuming the water consumption rate is 4 L/cap/day for a family of five with a rainwater collection area of 15 m(2)). If the water use rate is 20 L/cap/day, the same cistern can provide water for 150 days of the year; however, although this is insufficient to supply water to meet the body burden equivalent guideline of 50 mu g/L. Results are provided also for different rooftop areas, sizes of cisterns and alternative arsenic guidelines [World Health Organization (WHO) and Bangladeshi]. These findings provide useful guidelines on supply options to meet sustainability targets of water supply. However, they also demonstrate that the use of cisterns cannot assist the meeting of the 10 mu g/L WHO target arsenic body burden, if the arsenic contamination in the groundwater is high (e. g., at 100 mu g/L).",
Arsenic,1025202,"Modulation of antioxidant defence system for arsenic detoxification in Indian mustard Abstract: This study investigates the modulation of antioxidant defence system of Indian mustard (cv. Pusa Jai Kisan) against the arsenic (As)-induced toxicity in 20-day-old plants, exposed to 5 and 25 microM As for 96 h in hydroponic culture. Reduction in plant growth, measured in terms of root and shoot dry weights, was insignificant with 5 microM, but highly significant with 25 microM As treatment. Shoots accumulated more As than roots. The extent of oxidative stress in the leaves was measured as the rate of lipid peroxidation. The As treatments significantly increased the activities of antioxidative enzymes (superoxide dismutase, ascorbate peroxidase and glutathione reductase) and the contents of antioxidants metabolites (glutathione and ascorbate), the increase being dependent on exposure time. Increase in the activity of catalase was not significant, however. In conclusion, Indian mustard was able to detoxify the low As level through induction of antioxidant defence mechanism.",
Arsenic,1340862,"Microarray genomic profile of mitochondrial and oxidant response in manganese chloride treated PC12 cells Abstract: Environmental or occupational exposure to high levels of manganese (Mn) can lead to manganism, a symptomatic neuro-degenerative disorder similar to idiopathic Parkinson's disease. The underlying mechanism of Mn neurotoxicity remains unclear. In this study, we evaluate the primary toxicological events associated with MnCl(2) toxicity in rat PC12 cells using whole genome cDNA microarray, RT-PCR, Western blot and functional studies. The results show that a sub-lethal dose range (38-300 ?M MnCl(2)) initiated slight metabolic stress evidenced by heightened glycolytic rate and induction of enolase/aldolase - gene expression. The largest shift observed in the transcriptome was MnCl(2) induction of heme-oxygenase 1 (HO-1) [7.7 fold, p&lt;0.001], which was further corroborated by RT-PCR and Western blot studies. Concentrations in excess of 300 ?M corresponded to dose dependent loss of cell viability which was associated with enhanced production of H(2)O(2) concomitant to elevation of gene expression for diverse antioxidant enzymes; biliverdin reductase, arsenite inducible RNA associated protein, dithiolethione-inducible gene-1 (DIG-1) and thioredoxin reductase 1. Moreover, Mn initiated significant reduction of gene expression of mitochondrial glutaryl-coenzyme A dehydrogenase (GCDH), an enzyme involved with glutaric acidemia, oxidative stress, lipid peroxidation and striatal degeneration observed in association with severe dystonic-dyskinetic movement disorder. Future research will be required to elucidate a defined role for HO-1 and GCDH in Mn toxicity.",
Arsenic,1597361,"Arsenic exposure induces the Warburg effect in cultured human cells Abstract: Understanding how arsenic exacts its diverse, global disease burden is hampered by a limited understanding of the particular biological pathways that are disrupted by arsenic and underlie pathogenesis. A reductionist view would predict that a small number of basic pathways are generally perturbed by arsenic, and manifest as diverse diseases. Following an initial observation that arsenite-exposed cells in culture acidify their media more rapidly than control cells, the report here shows that low level exposure to arsenite (75ppb) is sufficient to induce aerobic glycolysis (the Warburg effect) as a generalized phenomenon in cultured human primary cells and cell lines. Expanded studies in one such cell line, the non-malignant pulmonary epithelial line, BEAS-2B, established that the arsenite-induced Warburg effect was associated with increased accumulation of intracellular and extracellular lactate, an increased rate of extracellular acidification, and inhibition by the non-metabolized glucose analog, 2-deoxyglucose. Associated with the induction of aerobic glycolysis was a pathway-wide induction of glycolysis gene expression, as well as protein accumulation of an established glycolysis master-regulator, hypoxia-inducible factor 1?. Arsenite-induced alteration of energy production in human cells represents the type of fundamental perturbation that could extend to many tissue targets and diseases.",
Arsenic,1252652,"Stereological analyses of hepatocyte changes parallel arsenic accumulation in the livers of green sunfish Abstract: Cellular changes in hepatocytes of green sunfish (Lepomis cyanellus) exposed to arsenic-contaminated or control lake water were compared with the level of arsenic in the liver. Standard stereological procedures involved conversion of two-dimensional data (i.e. fractional measurements of morphological changes) to three-dimensional data for interpretation. Both the volume and numbers of nuclei increased slightly with increasing concentration of arsenic in the liver. Significant increases (p less than 0.01) were observed in the volumes occupied by necrotic and fibrous bodies as arsenic levels in the liver increased; linear regression analysis of these data resulted in 0.9066 and 0.9359 correlation coefficients for necrotic and fibrous bodies, respectively, when volume changes were considered on a unit body weight basis. The volume occupied by necrotic areas, abnormal lysosomes, and autophagic vacuoles increased with increased arsenic concentration. The surface density of rough endoplasmic reticulum increased with increasing arsenic concentration; linear regression resulted in a correlation coefficient of 0.8367 when data were based on unit body weight.",
Arsenic,1022146,"A modified batch reactor system to study equilibrium-reactive transport problems Abstract: It is difficult to design column experiments to study transport processes involving slow geochemical reactions that require long residence times to reach equilibrium. We propose a sequential equilibration reactor (SER) setup to study such equilibrium geochemical reactive transport problems. The proposed system consists of sequentially operated batch reactors that directly mimic typical one-dimensional grids used in numerical reactive transport models. The SER experimental setup has the characteristics of batch experiments and provides complete control over the reaction time; in addition, the setup also includes certain simple transport features. We conducted several single-reactor and multiple-reactor SER experiments to investigate arsenic adsorption and transport on iron-oxide coated sand, at different pH, solid-solution ratio, and initial arsenic concentration conditions. The data generated from the experiments are compared against predictions from a geochemical transport code (PHREEQCI) that used previously developed surface complexation model parameters to describe the reaction system. The model predictions matched the SER experimental data well. The proposed SER system provides a flexible alternative to column experiments and allows better control over system parameters such as pH, reaction time, and solid-solution ratio.",
Arsenic,903707,"Cross-sectional exposure assessment of environmental contaminants in Churchill County, Nevada Abstract: Background: Having identified an increased number of childhood leukemia cases within Churchill County, Nevada, the Nevada State Health Division requested that CDC conduct a cross-sectional exposure assessment to identify contaminants unique to that community. Methods: 14 children with ALL or AML, and 55 age and gender matched controls were enrolled. Questionnaire data and biologic samples were collected from the cases, controls, and their immediate family. Environmental samples from current and previous homes within the county were collected. All samples were tested for metals, volatile organic compounds, PCBs, and pesticides. Results: 205 participants were enrolled. No positive association was found between the analytes measured and the case families. Tungsten urine levels were significantly greater in study participants (mean = 1.19 ?g/L, 95% CI 0.89?1.59) than in the US population (mean = 0.08 ?g/L). The median level of urine arsenic was 37.40 ?g/L (range 0?1180.40 ?g/L) with 34% of the participants above the normal threshold (50.0 ?g/L). Tungsten and arsenic were also detected in most of the tap water samples collected. Five nonpersistent and one persistent pesticide were elevated when compared with the US population. Conclusion: This investigation identified several environmental exposures of concern among Churchill County residents. Steps are being taken to further define the health implications of these exposures and to pursue genetic testing related to the metabolism of these chemicals. Specific recommendations have been made to decrease personal exposure.",
Arsenic,1788782,"Effects of chloride, sulfate and natural organic matter (NOM) on the accumulation and release of trace-level inorganic contaminants from corroding iron Abstract: This study examined effects of varying levels of anions (chloride and sulfate) and natural organic matter (NOM) on iron release from and accumulation of inorganic contaminants in corrosion scales formed on iron coupons exposed to drinking water. Changes of concentrations of sulfate and chloride were observed to affect iron release and, in lesser extent, the retention of representative inorganic contaminants (vanadium, chromium, nickel, copper, zinc, arsenic, cadmium, lead and uranium); but, effects of NOM were more pronounced. DOC concentration of 1 mg/L caused iron release to increase, with average soluble and total iron concentrations being four and two times, respectively, higher than those in the absence of NOM. In the presence of NOM, the retention of inorganic contaminants by corrosion scales was reduced. This was especially prominent for lead, vanadium, chromium and copper whose retention by the scales decreased from &gt;80% in the absence of NOM to &lt;30% in its presence. Some of the contaminants, notably copper, chromium, zinc and nickel retained on the surface of iron coupons in the presence of DOC largely retained their mobility and were released readily when ambient water chemistry changed. Vanadium, arsenic, cadmium, lead and uranium retained by the scales were largely unsusceptible to changes of NOM and chloride levels. Modeling indicated that the observed effects were associated with the formation of metal-NOM complexes and effects of NOM on the sorption of the inorganic contaminants on solid phases that are typical for iron corrosion in drinking water.",
Arsenic,1015943,"In vitro study of intestinal transport of arsenite, monomethylarsonous acid, and dimethylarsinous acid by Caco-2 cell line Abstract: Arsenic is a pollutant widely distributed in the environment. There are numerous studies on the toxicity of trivalent arsenic forms As(III), MMA(III), and DMA(III), but few data are available on the processes of digestion and absorption of these arsenic species and the mechanisms involved are unknown. The present study evaluated the processes involved in intestinal absorption of trivalent arsenic species, using the Caco-2 cell model as system. The apparent permeability values obtained for As(III) in apical-basolateral direction (4.6±0.3)×10(-6)cm/s, showing moderate intestinal absorption. Transport of MMA(III) [P(app)=(7.0±0.9)×10(-6)cm/s] and DMA(III) [P(app)=(10.6±1.4)×10(-6)cm/s] is greater than that of As(III). The cellular retention of As(III) (0.9-2.4%) was less than that observed for MMA(III) (30%) and DMA(III) (35%). A substantial paracellular component was observed in transport of As(III) and MMA(III), whereas DMA(III) does not use this pathway for its absorption. For all the trivalent species, transport depends on temperature, with an active transcellular component for MMA(III) and DMA(III). Variations in pH do not affect transport of these species. The presence of GSH and green tea extract significantly alters transport of As(III) across Caco-2 cells.",
Arsenic,1255512,"Analysis of arsenic and antimony distribution within plants growing at an old mine site in Ouche (Cantal, France) and identification of species suitable for site revegetation Abstract: One of the objectives of this study was to assess the contamination levels in the tailings of an old antimony mine site located in Ouche (Cantal, France). Throughout the 1.3 ha site, homogenous concentrations of antimony and arsenic, a by-product of the operation, were found along 0-0.5 m-deep profiles. Maximum concentrations for antimony and arsenic were 5780 mg kg(-1) dry tailings and 852 mg kg(-1) dry tailings, respectively. Despite the presence of the contaminants and the low pH and organic matter contents of the tailings, several patches of vegetation were found. Botanical identification determined 12 different genera/species. The largest and most abundant plants were adult pines (Pinus sylvestris), birches (Betula pendula) and the bulrush (Juncus effusus). The distribution of the metalloids within specimens of each genera/species was analysed in order to deduce their concentration and translocation capacities. This was the second goal of this work. All plant specimens were highly contaminated with both metalloids. Most were root accumulators with root to shoot translocation factors &lt;1. Whereas contamination levels were high overall, species with both a low translocation factor and a low root accumulation coefficient were identified as suitable candidates for the complete revegetation of the site. Species combining those characteristics were the perennials P.sylvestris, B.pendula, Cytisus scoparius and the herbaceous Plantago major, and Deschampsia flexuosa.",
Arsenic,666336,"Chronic arsenic exposure and oxidative stress: OGG1 expression and arsenic exposure, nail selenium, and skin hyperkeratosis in inner Mongolia Abstract: Arsenic, a human carcinogen, is known to induce oxidative damage to DNA. In this study we investigated oxidative stress and As exposure by determining gene expression of OGG1, which codes for an enzyme, 8-oxoguanine DNA glycosylase, involved in removing 8-oxoguanine in As-exposed individuals. Bayingnormen (Ba Men) residents in Inner Mongolia are chronically exposed to As via drinking water. Water, toenail, and blood samples were collected from 299 Ba Men residents exposed to 0.34–826 ?g/L As. RNA was isolated from blood, and mRNA levels of OGG1 were determined using real-time polymerase chain reaction. OGG1 expression levels were linked to As concentrations in drinking water and nails, selenium concentrations in nails, and skin hyperkeratosis. OGG1 expression was strongly associated with water As concentrations (p < 0.0001). Addition of the quadratic term significantly improved the fit compared with the linear model (p = 0.05). The maximal OGG1 response was at the water As concentration of 149 ?g/L. OGG1 expression was also significantly associated with toenail As concentrations (p = 0.015) but inversely associated with nail Se concentrations (p = 0.0095). We found no significant differences in the As-induced OGG1 expression due to sex, smoking, or age even though the oldest group showed the strongest OGG1 response (p = 0.0001). OGG1 expression showed a dose-dependent increased risk of skin hyperkeratosis in males (trend analysis, p = 0.02), but the trend was not statistically significant in females. The results from this study provide a linkage between oxidative stress and As exposure in humans. OGG1 expression may be useful as a biomarker for assessing oxidative stress from As exposure.",
Arsenic,1339385,"Effect of fluoride exposure on the intelligence of school children in Madhya Pradesh, India Abstract: <strong>OBJECTIVE: </strong>To assess the relationship between exposure to different drinking water fluoride levels and children's intelligence in Madhya Pradesh state, India.<br /><br /><strong>MATERIALS AND METHODS: </strong>This cross-sectional study was conducted among 12-year-old school children of Madhya Pradesh state, India. The children were selected from low (< 1.5 parts per million) and high (?1.5 parts per million) fluoride areas. A questionnaire was used to collect information on the children's personal characteristics, residential history, medical history, educational level of the head of the family, and socioeconomic status of the family. Levels of lead, arsenic, and iodine in the urine and the levels of fluoride in the water and urine were analyzed. The children's intelligence was measured using Raven's Standard Progressive Matrices. Data analysis was done using the chi-square, one way analysis of variance, simple linear regression, and multiple linear regression tests. P value <0.05 was considered statistically significant.<br /><br /><strong>RESULTS: </strong>Differences in participant's sociodemographic characteristics, urinary iodine, urinary lead, and urinary arsenic levels were statistically not significant (P>0.05). However, a statistically significant difference was observed in the urinary fluoride levels (P 0.000). Reduction in intelligence was observed with an increased water fluoride level (P 0.000). The urinary fluoride level was a significant predictor for intelligence (P 0.000).<br /><br /><strong>CONCLUSION: </strong>Children in endemic areas of fluorosis are at risk for impaired development of intelligence.",
Arsenic,1579402,Response of adenine and pyridine metabolism during germination and early seedling growth under arsenic stress in Brassica juncea Abstract: ,
Arsenic,1519083,"Impact of iron precipitant on toxicity of arsenic in water: A combined in vivo and in vitro study Abstract: Removing arsenic (As) from drinking water is widely dependent on iron (Fe)-based coagulation/flocculation techniques. However, little is known about the influence of Fe precipitant on As toxicity. In this present study, the influence of Fe on As toxicity was determined at systems biology level by in vitro and in vivo experiments. In vitro study based on HepG2 cell line found that Fe increased the As toxicity on cell viability and DNA damage, indicating the synergetic toxic effects. However, when the Fe and As were simultaneously exposed to mice by drinking water for 90 days, the results showed that Fe reduced the changes of hepatic transcriptomic profiles and serum and urine metabolic profiles caused by As exposure, showing the antagonistic toxic effects. The antagonistic effects might be because Fe reduced As bioavailability and accumulation, which was verified by As and Fe levels in feces and liver. The results of this study indicate that Fe precipitant can influence the As toxicity. The interactions between As and Fe and their bioavailability might play important roles in the As toxicity. When assessing the safety of As in drinking water, it is necessary to fully consider the combined effects of As and Fe.",
Arsenic,1797789,"An evaluation of water quality in private drinking water wells near natural gas extraction sites in the Barnett Shale formation Abstract: Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques. Analyses revealed that arsenic, selenium, strontium and total dissolved solids (TDS) exceeded the Environmental Protection Agency's Drinking Water Maximum Contaminant Limit (MCL) in some samples from private water wells located within 3 km of active natural gas wells. Lower levels of arsenic, selenium, strontium, and barium were detected at reference sites outside the Barnett Shale region as well as sites within the Barnett Shale region located more than 3 km from active natural gas wells. Methanol and ethanol were also detected in 29% of samples. Samples exceeding MCL levels were randomly distributed within areas of active natural gas extraction, and the spatial patterns in our data suggest that elevated constituent levels could be due to a variety of factors including mobilization of natural constituents, hydrogeochemical changes from lowering of the water table, or industrial accidents such as faulty gas well casings.",
Arsenic,1519164,Arsenic Distribution in Soils of a Former As Mining Area and Processing Abstract: ,
Arsenic,1022913,"Genetic predisposition to the cytotoxicity of arsenic: the role of DNA damage and ATM Abstract: Arsenic is a pervasive cytotoxin and carcinogen in the environment. Although its mode of action has yet to be fully elucidated, oxidative DNA damage has been suggested. A series of DNA repair-defective human and hamster cell lines associated with sensitivity to oxidative agents were examined for their response to arsenic-induced cytotoxicity. Only the Ataxia telangiectasia (AT) cells displayed a marked hypersensitive response (greater than twofold). The protective role of the ATM protein was confirmed by the normal response to arsenic displayed by AT cells expressing wild-type ATM. Although the ATM protein plays a pivotal role in response to DNA double-strand breakage, none of the other cell lines with defects in double-strand break repair displayed a similar hypersensitivity. Further examination indicated that concentrations of sodium arsenite as high as 1 mg/l do not generate significant levels of double-strand breaks. Our data suggest that the ATM protein functions in an important but different capacity in the cellular response to arsenic toxicity than it does in response to agents that generate double-strand breaks, such as ionizing radiation. Furthermore, the lack of hypersensitivity to arsenic displayed by the other cell lines calls into question the hypothesis that DNA damage is a significant factor in arsenic cytotoxicity.",
Arsenic,1070504,"Effect of water management, arsenic and phosphorus levels on rice in a high-arsenic soil-water system: II. Arsenic uptake Abstract: Rice consumption is one of the major pathways for As intake in populations that depend on a rice diet in several countries of South and South-east Asia. Pot experiments were undertaken to investigate the effects of water management (WM), arsenic (As) contaminated soil-water and Phosphorus (P) rates on As uptake in rice plants. There were 18 treatments comprising of three each of As rates (0, 20 and 40mgkg(-1) soil) and P rates (0, 12.5 and 25mgkg(-1) soil) and two WM (aerobic and anaerobic) strategies on winter (boro var. BRRI dhan 29) and monsoon (aman var. BRRI dhan 32) rice at the Wheat Research Center (WRC), Nashipur, Dinajpur, Bangladesh. Arsenic concentrations in rice grain and straw increased significantly ((??)P?0.01) with the increasing As rates in the soil. Arsenic availability in soil pore-water solution was less (58%) under aerobic WM (redox potential-Eh=+135 to +138mV; pH-6.50 at 24.3°C) as compared to anaerobic WM (flooded: Eh=-41 to -76mV; pH-6.43 at 23°C). The highest total grain As content 2.23±0.12mgkg(-1) and 0.623±0.006mgkg(-1) was found in T(6) (P(12.5)As(40)-anaerobic) and T(9) (P(25)As(40)-anaerobic) in BRRI dhan 29 and BRRI dhan 32, respectively, which was significantly higher (41-45%) than in the same As and P treatments for pots under aerobic WM. The As content in rice straw (up to 24.7±0.49ppm in BRRI dhan 29, 17.3±0.49mgkg(-1) in BRRI dhan 32 with the highest As level) suggested that As can more easily be translocated to the shoots under anaerobic conditions than aerobic condition. BRRI dhan 29 was more sensitive to As than BRRI dhan 32. Under aerobic WM, P soil amendments reduced As uptake by rice plants. The study demonstrated that aerobic water management along with optimum P amendment and selection of arsenic inefficient rice varieties are appropriate options that can be applied to minimize As accumulation in rice which can reduce effects on human and cattle health risk as well as soil contamination.",
Arsenic,627867,"Ischemic heart disease mortality reduction in an arseniasis-endemic area in southwestern Taiwan after a switch in the tap-water supply system Abstract: Arsenic has been identified as a major contributing risk factor for development of blackfoot disease (BFD), a unique peripheral vascular disease that was endemic to the southwestern coast of Taiwan, where residents imbibed artesian well water continuing high amounts of arsenic for more than 50 yr. Chronic arsenic exposure was found to be associated with ischemic heart disease (CHD) in a dose-dependent manner. A tap-water supply system was implemented in the early 1960s in the BFD-endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study was to examine whether CHD-related mortality decreased after consumption of high-arsenic-containing artesian well water ceased and, if so, when the reduction occurred. Standardized mortality ratios (SMRs) for CHD were calculated for the BFD endemic area for the years 1971-2000. Cumulative-sum techniques were used to detect the occurrence of changes in the SMRs. Data show that mortality attributed to CHD declined gradually for approximately 17 to 20 yr following cessation of consumption of high-arsenic artesian well water. Based on the reversibility criterion, the association between arsenic exposure an1rd CHD-related mortality is likely to be causal. Copyright Taylor & Francis Inc.",
Arsenic,1351975,"An improved HPLC-ICPMS method for determining inorganic arsenic in food: Application to rice, wheat and tuna fish Abstract: ",
Arsenic,1251021,"Arsenate V induced glutathione efflux from human erythrocytes Abstract: <strong>OBJECTIVE: </strong>The objective of the present study was to investigate if arsenate V exposure results in glutathione efflux from human erythrocytes.<br /><br /><strong>PROCEDURE: </strong>The changes in intracellular and extracellular nonprotein sulfhydryl and glutathione levels were determined in arsenate (V) exposed erythrocytes. Presence of any cellular membrane damage was assessed by lactate dehydrogenase activity measurement in the supernatant.<br /><br /><strong>RESULTS: </strong>When erythrocytes were exposed to 10 mM of arsenate (V) for 4 h, the intracellular NPSH level decreased to 0.28±0025 ?mol/ml erythrocyte. In contrast, extracellular nonprotein thiol level was increased to 0.180±0.010 ?mol/ml erythrocyte in 4 h. Extracellular glutathione levels reached to 0.028±0.001, 0.052±0.002, and 0.054±0.004 ?mol/ml erythrocyte with 1, 5, and 10 mM of arsenate (V), respectively. Utilization of MK571 a multi drug resistance-associated protein 1 inhibitor decreased the rate of glutathione efflux from erythrocytes suggesting a role for this membrane transporter in the process.<br /><br /><strong>CONCLUSION: </strong>The results of the present study indicate that erythrocytes efflux glutathione when exposed to arsenate (V).",
Arsenic,2347678,"Pristine Arctic: Background mapping of PAHs, PAH metabolites and inorganic trace elements in the North-Atlantic Arctic and sub-Arctic coastal environment Abstract: As the ice cap of the Arctic diminishes due to global warming, the polar sailing route will be open larger parts of the year. These changes are likely to increase the pollution load on the pristine Arctic due to large vessel traffic from specific contaminant groups, such as polycyclic aromatic hydrocarbons (PAHs). A well-documented baseline for PAH concentrations in the biota in the remote regions of the Nordic Seas and the sub-Arctic is currently limited, but will be vital in order to assess future changes in PAH contamination in the region. Blue mussels (Mytilus edulis) were collected from remote sites in Greenland, Iceland, the Faroe Islands, Norway and Sweden as well as from urban sites in the same countries for comparison. Cod (Gadus morhua) was caught north of Iceland and along the Norwegian coast. Sixteen priority PAH congeners and the inorganic trace elements arsenic, cadmium, mercury and lead were analysed in the blue mussel samples as well as PAH metabolites in cod bile. ?16PAHs ranged from 28ng/g dry weight (d.w.) (Álftafjörður, NW Iceland) to 480ng/g d.w. (Ísafjörður, NW Iceland). Mussel samples from Mjóifjörður, East Iceland and Maarmorilik, West Greenland, contained elevated levels of ?16PAHs, 370 and 280ng/g d.w., respectively. Levels of inorganic trace elements varied with highest levels of arsenic in mussels from Ísafjörður, Iceland (79ng/g d.w.), cadmium in mussels from Mjóifjörður, Iceland (4.3ng/g d.w.), mercury in mussels from Sørenfjorden, Norway (0.23ng/g d.w.) and lead in mussels from Maarmorilik, Greenland (21ng/g d.w.). 1-OH-pyrene was only found above limits of quantification (0.5ng/mL) in samples from the Norwegian coast, ranging between 44 and 140ng/ml bile. Generally, PAH levels were low in mussels from the remote sites investigated in the study, which indicates limited current effect on the environment.",
Arsenic,86147,"Mortality in the Swedish glassworks industry Abstract: An earlier, relatively small case-referent study has shown an increased risk for glassworks employees to die from stomach cancer, lung cancer, and cardiovascular disorders. This observation suggested an extended study virtually covering the entire glass-producing industry of Sweden. This new study confirmed the earlier results and, furthermore, an excess risk for colon cancer was also identified. No deviation was found in the cancer mortality pattern for all men in the glass-producing area compared to the whole of Sweden. The grouping of glassworks employees according to type of metal consumption at the glassworks showed the excess risks of stomach cancer, colon cancer, and cardiovascular deaths to relate to glassworks with a high consumption of lead, arsenic, antimony, and manganese. However, the strong correlation of these various metal exposures did not permit any successful separation of the effects of the different metals. For cardiovascular mortality, as for cancer, the glassblowers especially suffered from increased risk. Their exposure might, to a great extent, be oral, involving the glassblower's pipe as a ""vector"" for the exposure to various metals.",
Arsenic,1070361,"Hypoxia-induced exposure of isaza fish to manganese and arsenic at the bottom of Lake Biwa, Japan: Experimental and geochemical verification Abstract: In December 2007, a mass mortality of isaza (Gymnogobius isaza), a goby fish in Lake Biwa, Japan, was observed under severe hypoxia. Considering the level of manganese and arsenic in the dead isaza during the event was much higher than that in live isaza, hypoxia-induced mobilization of manganese and arsenic and subsequent exposure could be the reason for this adverse effect. However, secondary accumulation of manganese and arsenic after the mortality event could not be ruled out. To test this hypothesis, we conducted tissue distribution/speciation analysis and absorption tests on dead specimens. All the results, particularly the limited absorption of arsenic in the absorption tests, indicated that the isaza were exposed to arsenic before the mortality event. Parallel to this, the geochemical behavior of manganese and arsenic in oxygen-rich conditions (June) and oxygen-poor conditions (December) was investigated to verify the mechanism of exposure. Considerable enrichment of manganese and arsenic in a thin surface layer of sediment was a common feature in all seven stations studied. In the water at the bottom of the lake, a clear increase of arsenite in December was observed, and the manganese level was several hundred times higher in both seasons than the average level of the lake. Although further verification is needed, the data provided here support exposure to manganese and arsenic under hypoxia.",
Arsenic,1252840,"Arsenic Carcinogenesis in Animals and in Humans: Mechanistic, Experimental and Epidemiological Evidence Abstract: The carcinogenicity of arsenic (7440382) was reviewed, sources of arsenic exposure were summarized, the historical background of the use of arsenic as a poison and in medicine was outlined, and the metabolism and disposition of arsenic were discussed. Ingested inorganic arsenicals, arsenates and arsenites, are quickly absorbed in both humans and experimental animals. They rapidly enter the blood stream where the arsenates are efficiently reduced to arsenites through reactions with glutathione and transported to the liver. In the liver, arsenite (1327533) undergoes methylation to methanearsonic-acid (124583) by a nonenzymatic process, and to monomethylarsonic-acid (124583) (MMA), and subsequently to dimethylarsinic-acid (75605) (DMA) by enzymatic processes. Methylated arsenicals produced metabolically from inorganic arsenicals are excreted faster and have a lower affinity for tissue sulfhydryl groups than inorganic arsenicals, especially arsenites. This suggests that methylation is a detoxification process. The toxicity and carcinogenicity of arsenic and possible mechanisms of action were discussed. In humans, dermal exposure to arsenic has been shown to cause skin cancer. Oral exposure from drinking arsenic contaminated well water has been shown to cause nonmelanoma skin cancer and other malignancies. Occupational exposure by way of inhalation leads to lung and skin cancer and other malignancies. Exposure to arsenic containing pesticides has also caused malignancies. The International Agency for Research on Cancer (IARC) has classified arsenic as a human carcinogen as well as the National Toxicology Program and the Environmental Protection Agency. Various arsenic compounds have been tested for carcinogenicity in experimental animals. Most of these have produced negative results. The few studies producing positive results have resulted in the IARC concluding that inadequate evidence exists for arsenic being classified as carcinogenic in experimental animals. Some of the studies have indicated that arsenic can induce tumors in animals if not quickly methylated and cleared. The question as to whether arsenic can induce tumors in experimental animals was considered. Several hypotheses have been proposed to explain why arsenic appears not to induce tumors in experimental animals. One suggests that experimental animals have greater methylation capacity for arsenicals than humans. It has also been postulated that arsenic carcinogenicity in humans may reflect simultaneous exposure to other carcinogens as well as to arsenic, whereas in experimental studies only the pure arsenical is used. Data needs and proposed experimental studies involving arsenic carcinogenicity were discussed.",
Arsenic,1349456,Geochemical characteristics of the mud volcano fluids in southwestern Taiwan and their possible linkage to elevated arsenic concentration in Chianan plain groundwater Abstract: ,
Arsenic,2279348,"Determination of sixteen elements and arsenic species in brown, polished and milled rice Abstract: The concentrations of 16 elements in 10 rice flour samples and the distribution of the elements in the rice grains from which the flour were made were determined by ICP-MS and ICP-OES after microwave-assisted digestion of the samples. Arsenic speciation analysis was carried out by HPLC-ICP-MS following heat-assisted extraction of the sample. The concentrations of inorganic As (As(III) and As(V)), monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) and their distribution in the rice grains were determined. Portions of the brown rice were polished/milled to different degrees to yield milled off samples and polished rice samples. All samples were powdered and analyzed for 16 elements and for As species. The recoveries and mass balances for all elements in all samples showed good agreements with the starting materials. As(III), As(V), MMAA and DMAA were detected, and the sums of the concentrations of all species in the extract were 86 - 105% of the total As concentration in each case.",
Arsenic,1033510,"Histologic changes in nude mouse skin and human skin xenografts following exposure to sulfhydryl reagents: Arsenicals Abstract: This report documents the histological changes in nude mouse skin and in human skin xenografts on nude mice following exposure to phenyldichloroarsine (PDA), a vesicant arsenical. Under light microscopy, we observed in PDA-treated human skin grafts: 1) degeneration of epidermal cell nuclei (apparent by 2 hr after exposure with increasing severity through 48 hr); 2) loss of epidermal cytoplasmic basophilia (apparent by 4 hr, maximal within 12 hr); 3) epidermal cytoplasmic vacuolization (vacuoles appeared within 4 hr and increased in size through 24 hr); 4) cleft formation within the basement membrane zone (apparent by 12 hr, increasing in severity through 24 hr); 5) inflammation evidenced by polymorphonuclear leukocyte (PMN) infiltration (apparent by 4 hr and increasing through 48 hr). The PMNs frequently formed a wall around the lesion, but did not infiltrate the treated area. Nude mouse skin reacted faster to PDA than did the grafts, but the histological changes were similar. Nude mouse hair follicles and sebaceous glands showed similar cellular changes at approximately the same time as did epidermal cells. Transmission electron microscopy of mouse skin exposed to PDA revealed a widening of intercellular spaces with attenuation of desmosomes. The subepidermal clefts resulted from separation within the lamina lucida with the lamina densa forming the base of the cleft. Diphenylchloroarsine caused lesions histologically indistinguishable from those of PDA. Lesions resulting from exposure to other sulfhydryl-binding compounds were very different from arsenical lesions. The arsenical-sensitive cellular constituents were not identified.",
Arsenic,1797795,"Photooxidation of Arsenite under 254 nm Irradiation with a Quantum Yield Higher than Unity Abstract: Arsenite (As(III)) in water was demonstrated to be efficiently oxidized to arsenate (As(V)) under 254 nm UV irradiation without needing any chemical reagents. Although the molar absorption coefficient of As(III) at 254 nm is very low (2.49±0.1 M(-1)cm(-1)), the photooxidation proceeded with a quantum yield over 1.0, which implies a chain of propagating oxidation cycles. The rate of As(III) photooxidation was highly enhanced in the presence of dissolved oxygen, which can be ascribed to its dual role as an electron acceptor of photo-excited As(III) and a precursor of oxidizing radicals. The in-situ production of H2O2 was observed during the photooxidation of As(III) and its subsequent photolysis under UV irradiation produced OH radicals. The addition of tert-butyl alcohol as OH radical scavengers significantly reduced (but not completely inhibited) the oxidation rate, which indicates that OH radicals as well as superoxide serve as an oxidant of As(III). Superoxide, H2O2, and OH radicals were all in situ generated from the irradiated solution of As(III) in the presence of dissolved O2 and their subsequent reactions with As(III) induce the regeneration of some oxidants, which makes the overall quantum yield higher than 1. The homogeneous photolysis of arsenite under 254 nm irradiation can be also proposed as a new method of generating OH radicals.",
Arsenic,2347774,"Effect of ageing on surface charge characteristics and adsorption behaviour of cadmium and arsenate in two contrasting soils amended with biochar Abstract: Biochar has been recognised as an effective amendment for the remediation of contaminated soils; however, there is limited knowledge on the effects of biochar ageing in soil on its adsorption behaviour for cationic and anionic species. Biochars are considered to develop negative charge from oxidation with ageing, which may create additional interaction mechanisms for adsorption processes. In the present study, surface charge characteristics and cadmium (Cd) and arsenate (AsO43-) adsorption behaviour of aged biochar were investigated in two soils with variable charge, an Oxisol and an Inceptisol, by comparing (i) unamended soils, and soils amended with (ii) fresh biochar (450 degrees C) and (iii) biochar (450 degrees C) aged for 12 months, applied at a rate of 2% w/w. Surface charge characteristics were assessed using the 'index' ion adsorption method, with a LiCl electrolyte. Batch adsorption studies were conducted using fresh and aged soil-biochar mixtures. In contrast to previous studies, the results provided no evidence of an increase in cation exchange capacity as a consequence of biochar ageing. There was an increase in Cd adsorption in the presence of aged biochar in both soil types compared with unamended soils and soils amended with fresh biochar. Results also indicated an increase in AsO43- adsorption in the Inceptisol amended with aged biochar, whereas a decrease in AsO43- adsorption was observed in the Oxisol amended with aged biochar. Overall, the study has highlighted that adsorption behaviour of aged biochar varies depending on the ion it interacts with, soil properties and solution pH.",
Arsenic,2064183,Synthesis of monodispersed alpha-FeOOH nanorods with a high content of surface hydroxyl groups and enhanced ion-exchange properties towards As(V) Abstract: ,
Arsenic,2088508,"Resolving the Enigma of the Mesoamerican Nephropathy: A Research Workshop Summary Abstract: The First International Research Workshop on Mesoamerican Nephropathy (MeN) met in Costa Rica in November 2012 to discuss how to establish the extent and degree of MeN, examine relevant causal hypotheses, and focus efforts to control or eliminate the disease burden. MeN describes a devastating epidemic of chronic kidney disease of unknown origin predominantly observed among young male sugarcane cutters. The cause of MeN remains uncertain; however, the strongest hypothesis pursued to date is repeated episodes of occupational heat stress and water and solute loss, probably in combination with other potential risk factor(s), such as nonsteroidal anti-inflammatory drug and other nephrotoxic medication use, inorganic arsenic, leptospirosis, or pesticides. At the research workshop, clinical and epidemiologic case definitions were proposed in order to facilitate both public health and research efforts. Recommendations emanating from the workshop included measuring workload, heat, and water and solute loss among workers; quantifying nephrotoxic agents in drinking water and food; using biomarkers of early kidney injury to explore potential causes of MeN; and characterizing social and working conditions together with methods for valid data collection of exposures and personal risk factors. Advantages and disadvantages of different population study designs were detailed. To elucidate the etiology of MeN, multicountry studies with prospective cohort design, preferably integrating an ecosystem health approach, were considered the most promising. In addition, genetic, experimental, and mechanistic methods and designs were addressed, specifically the need for kidney biopsy analysis, studies in animal models, advances in biomarkers, genetic and epigenetic studies, a common registry and repository of biological and demographic data and/or specimens, and other areas of potential chronic kidney disease experimental research. Finally, in order to improve international collaboration on MeN, workshop participants agreed to establish a research consortium to link these Mesoamerican efforts to other efforts worldwide.",
Arsenic,1348138,"Recent Research on Folate Intake, Rice Products, Fiber Intake, and Enzyme Degradation of Gluten Abstract: ",
Arsenic,734963,"Subcellular distribution of inorganic and methylated arsenic compounds in human urothelial cells and human hepatocytes Abstract: Epidemiological studies have indicated that exposure of humans to inorganic arsenic in drinking water is associated with the occurrence of bladder cancer. The mechanisms by which arsenic induces this malignancy are still uncertain; however, arsenic metabolites are suspected to play a pivotal role. The aim of the present study was the investigation of uptake capabilities of human urothelial cells (UROtsa) compared with primary human hepatocytes (phH) as well as the intracellular distribution of the arsenic species. Additionally, we were interested in the cyto- and genotoxic potential (comet assay, radical generation) of the different arsenic compounds in these two cell types. Our results show that UROtsa cells accumulate higher amounts of the arsenic species than the phH. Differential centrifugation revealed that the arsenic compounds are preferentially distributed into nuclei and ribosomes. After 24-h exposure, arsenic is mainly found in the ribosomes of UROtsa cells and in the nuclei and mitochondria of phH. In contrast to the pentavalent arsenic species, the trivalent species induced a 4- to 5-fold increase of DNA damage in hepatocytes. Radical generation, measured by thiobarbituric acid reactive substances, was more pronounced in hepatocytes than in urothelial cells. In summary, the uptake of arsenic compounds appears to be highly dependent upon cell type and arsenic species. The nonmethylating urothelial cells accumulate higher amounts of arsenic species than the methylating hepatocytes. However, cyto- and genotoxic effects are more distinct in hepatocytes. Further studies are needed to define the implications of the observed accumulation in cellular organelles for the carcinogenic activity of arsenic.",
Arsenic,1345877,"Increased heat shock protein 70 expression following toxicant-mediated cytotoxicity: A ubiquitous marker of toxicant exposure? Abstract: The up-regulation of heat shock protein (HSP) expression has been proposed as a general biomarker of cellular protection against various environmental stresses and chemicals. The present study investigated the possibility of using HSP70 up-regulation as a biomarker of toxicant exposure in vitro. Cells of a rat hepatoma cell line (FGC4) were exposed to concentrations of 1,3-dichloroacetone, duroquinone, diquat dibromide, menadione, hydrogen peroxide, cadmium chloride (CdCl2) and sodium (meta)arsenite (NaAsO2) that elicited 20-50% cytotoxicity over a 24-hour period, and HSP70 levels were measured by ELISA. Up-regulation of HSP70 expression was demonstrated following treatment with menadione, CdCl2 and NaAsO2, but not with the other chemicals tested. A shorter exposure time (6 hours) and/or the use of non-toxic concentrations reduced the level of HSP70 up-regulation with menadione, CdCl2 and NaAsO2, but did not uncover any up-regulation with the other chemicals. Although the toxicity of the majority of the chemicals tested is believed to involve an oxidative stress component, the results of this study clearly demonstrate that up-regulation of HSP70 expression cannot be used as a general biomarker of toxicant exposure in vitro.",
Arsenic,2347513,"Lung tumors in mice induced by ""whole-life"" inorganic arsenic exposure at human-relevant doses Abstract: In mice, inorganic arsenic in the drinking water in the parts per million range via the dam during in utero life or with whole-life exposure is a multi-site carcinogen in the offspring. However, human arsenic exposure is typically in the parts per billion (ppb) range. Thus, we studied &quot;whole-life&quot; inorganic arsenic carcinogenesis in mice at levels more relevant to humans. Breeder male and female CD1 mice were exposed to 0, 50, 500 or 5,000 ppb arsenic (as sodium arsenite) in the drinking water for 3 weeks prior to breeding, during pregnancy and lactation, and after weaning (at week 3) groups of male and female offspring (initial n = 40) were exposed for up to 2 years. Tumors were assessed in these offspring. Arsenic exposure had no effect on pregnant dam weights or water consumption, litter size, offspring birthweight or weight at weaning compared to control. In male offspring mice, arsenic exposure increased (p &lt; 0.05) bronchiolo-alveolar tumor (adenoma or carcinoma) incidence at 50-ppb group (51 %) and 500-ppb group (54 %), but not at 5,000-ppb group (28 %) compared to control (22 %). These arsenic-induced bronchiolo-alveolar tumors included increased (p &lt; 0.05) carcinoma at 50-ppb group (27 %) compared to controls (8 %). An increase (p &lt; 0.05) in lung adenoma (25 %) in the 50-ppb group compared to control (11 %) occurred in female offspring. Thus, in CD1 mice whole-life arsenic exposure induced lung tumors at human-relevant doses (i.e., 50 and 500 ppb).",
Arsenic,737398,"Respiratory cancer and inhaled inorganic arsenic in copper smelters workers: A linear relationship with cumulative exposure that increases with concentration Abstract: Inhalation of high levels of airborne inorganic arsenic is a recognized cause of respiratory cancer. Although multiple epidemiologic studies have demonstrated this association, there have been few analyses of the mathematical relationship between cumulative arsenic exposure and risk of respiratory cancer, and no assessment as to whether and how arsenic concentration may modify this association.<br /><br /> The objective is an evaluation of the shape of the relationship between respiratory cancer mortality and cumulative inhaled arsenic exposure among copper smelter workers, and the modification of that relationship by arsenic concentration.<br /><br /> We used Poisson regression methods to analyze data from a cohort of arsenic-exposed copper smelter workers under a linear-exponential model for the excess relative risk.<br /><br /> Within categories of arsenic concentration, the association between respiratory cancer and cumulative arsenic exposure was consistent with linearity. The slope of the linear relationship with cumulative exposure increased with increasing arsenic concentration category.<br /><br /> Our results suggested a direct concentration effect from inhaled inorganic arsenic, whereby the excess relative risk for a fixed cumulative exposure was greater when delivered at a higher concentration and shorter duration than when delivered at a lower concentration and longer duration.",
Arsenic,2337280,"Outcomes and treatment patterns as a function of time in stage IS testicular seminoma: A population-based analysis Abstract: <strong>OBJECTIVES: </strong>To assess outcomes and treatment patterns as a function of time in stage IS pure testicular seminoma patients using a population-based analysis.<br /><br /><strong>METHODS: </strong>One thousand one hundred and fifty-two stage I testicular seminoma patients with normal alpha-fetoprotein levels were identified in the Surveillance, Epidemiology, and End Results (SEER) database between 1998 and 2005. Three hundred and twenty-three of these patients had persistent elevations of their serum lactate dehydrogenase (LDH) and/or beta subunit of human chorionic gonadotropin (bHCG) level post-orchiectomy, i.e., &quot;stage IS&quot; disease.<br /><br /><strong>RESULTS: </strong>Median follow-up was 86 months. There was persistent elevation of LDH or bHCG levels post-orchiectomy in 19% and 15% stage I patients, respectively. Post-orchiectomy LDH and bHCG did not predict overall survival (OS) or cause-specific survival (CSS) in stage IS patients. There was a decrease in utilization of adjuvant RT in stage IS patients from 1998 (100%) to 2005 (58%, p=.01). The annual percentage decrease in RT utilization for stage IS patients was -5.4% (95% confidence interval: -7.7% to -3.9%). Modern, linear accelerator-based RT was associated with an improvement in OS. However, longer follow up is necessary to determine if the OS benefit persists.<br /><br /><strong>CONCLUSIONS: </strong>Post-orchiectomy LDH and bHCG did not predict OS or CSS in stage IS patients. There was a steady decrease in utilization of adjuvant RT in the United States in stage IS testicular seminoma patients between 1998 and 2005. This may be due to the increasing popularity of chemotherapy or active surveillance.",
Arsenic,1338847,"Prediction of macroscopic findings of hepatocellular carcinoma on hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging: Correlation with pathology Abstract: AIM: We aimed to correlate the macroscopic and magnetic resonance imaging (MRI) findings of hepatocellular carcinomas (HCC). METHODS: This was a multicenter study, whose study protocol was approved by each institutional review board. One hundred and forty-six resected nodules in 124 patients who had received a preoperative hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced MRI (EOB-MRI) were analyzed. In both findings, we compared the diameter of HCC and macroscopic types divided into five types: (i) small nodular type with indistinct margin (SN-IM); (ii) simple nodular type (with distinct margin) (SN-DM); (iii) simple nodular type with extranodular growth (SN-EG); (iv) confluent multinodular type (CMN); and (v) infiltrative type (IF). RESULTS: The diameters in each finding (D(surg) and D(MRI) ) were significantly correlated (R?=?0.961), although D(surg) was larger than D(MRI) (P?=?0.0216). There were significant differences between D(surg) in SN-IM and the other groups (P?&lt;?0.0001). Sensitivity, specificity and accuracy were 5.3, 99.2 and 87; 84.8, 62.7 and 81.4; 58.1, 91.3 and 84.2; 70.6, 91.5 and 89, in SN-IM, SN-DM, SN-EG and CMN, respectively. The kappa value of every size was as follows: all sizes, 0.45; 20?mm or less, 0.23; more than 20?mm, 0.56. CONCLUSION: EOB-MRI could predict the macroscopic pathological findings except for SN-IM. Small tumor size might be helpful to diagnose SN-IM.",
Arsenic,1579391,"Exceedance of air quality standards resulting from pyro-metallurgical production of copper: a case study, Bor (Eastern Serbia) Abstract: This study represents air quality data of SO2 and As concentrations around the mining-metallurgical complex Bor (Serbia) from 1994 to 2008. Daily and annual SO2 concentrations greatly exceed current air quality standards in the studied area. The ""hot spot"" with the highest SO2 and As annual concentrations during 15 years was the urban-industrial area (the town core). Daily SO2 concentrations and meteorological parameters during the period from 2005 to 2008 were statistically analysed to develop suitable prediction equations for daily SO2 concentrations. Anode copper production is an important but not the only factor that has influence on SO2 concentrations. By stepwise multiple linear regression analysis, it was determined that daily SO2 concentrations are most influenced by maximum wind gust, relative humidity and air temperature at all the measuring sites. The prediction equations of daily SO2 concentrations represent a good model with regression coefficients from 0.854 to 0.926 at all the measuring sites. Correlation analysis showed that eastern and western winds increase SO2 concentrations, thus increasing the health risk of the inhabitants in the study area.",
Arsenic,620261,"Arsenic Requires Sphingosine-1-Phosphate Type 1 Receptors to Induce Angiogenic Genes and Endothelial Cell Remodeling Abstract: Arsenic in drinking water is a major public health concern as it increases risk and incidence of cardiovascular disease and cancer. Arsenic exposure affects multiple vascular beds, promoting liver sinusoidal capillarization and portal hypertension, ischemic heart disease, peripheral vascular disease, and tumor angiogenesis. While Rac1-GTPase and NADPH oxidase activities are essential for arsenic-stimulated endothelial cell signaling for angiogenesis or liver sinusoid capillarization, the mechanism for initiating these effects is unknown. We found that arsenic-stimulated cell signaling and angiogenic gene expression in human microvascular endothelial cells were Pertussis toxin sensitive, indicating a G-protein coupled signaling pathway. Incubating human microvascular endothelial cells with the sphingosine-l-phosphate type 1 receptor (S1P(1)) inhibitor VPC23019 or performing small interfering RNA knockdown of S1P(1) blocked arsenic-stimulated HMVEC angiogenic gene expression and tube formation, but did not affect induction of either HMOX1 or IL8. Liver sinusoidal endothelial cells (LSECs) defenestrate and capillarize in response to aging and environmental oxidant stresses. We found that S1P(1) was enriched on LSECs in vivo and in primary cell culture and that VPC23019 inhibited both sphingosine-1-phosphate-stimulated and arsenic-stimulated LSEC oxidant generation and defenestration. These studies identified novel roles for S1P(1) in mediating arsenic stimulation of both angiogenesis and pathogenic LSEC capillarization, as well as demonstrating a role for S1P(1) in mediating environmental responses in the liver vasculature, providing possible mechanistic insight into arsenic-induced vascular pathogenesis and disease. (Am J Pathol 2009, 174:1949-1958; DOI: 10.2353/ajpath.2009.081016)",
Arsenic,1347050,Change in minerals bioavailability in chronic arsenic toxicity with or without methionine and betaine supplementation in layer chicken Abstract: ,
Arsenic,1509352,"Acclimation of arsenic-resistant Fe(II)-oxidizing bacteria in aqueous environment Abstract: This study investigated the potential of the Fe(II)-oxidizing bacteria in removing arsenic in aqueous environment. The bacteria were isolated from the batch of tap water and rusty iron wires, and were acclimated to culture media amended with arsenic concentrations, gradually increasing from 100 ?g L?1 to 100 mg L?1. Acclimated bacteria with enhanced arsenic tolerance were used to remove arsenic from the aqueous solution. These bacteria belonged to Pseudomonas species according to 16S rRNA gene sequences. Extracellular enzymes produced by these bacteria played important roles in microbial Fe(II) oxidization and Fe oxide precipitation. Moreover, these bacteria survived and propagated in high arsenic condition (100 mg L?1 As). However, after As(III/V) acclimation, morphological characteristics of the bacteria showed some changes, e.g., shrinking of long bacillus. XRD (X-ray diffraction) patterns indicated that Fe oxide precipitations by Fe(II)-oxidizing bacteria in Fe-rich culture medium were poorly-crystallized ferrihydrites. Adsorption on the biogenic ferrihydrites greatly contributed to high arsenic removal efficiency of Fe(II)-oxidizing bacteria.",
Arsenic,1579385,"Comparison of neurobehavioral and biochemical effects in rats exposed to dusts from copper smelter plant at different locations Abstract: Mixed exposure to metals (including arsenic and lead) associated with the neurological and respiratory effects constitute one of the major health problems of copper smelting. Chemical composition of the dust, and the expected health effect of inhalation can be very diverse at different parts of the smelter plant. The aims of this study were to compare lung responses and behavioral effects in female Wistar rats after instillation of dust collected from different production processes at the same smelter department. Dusts collected at two different locations of furnace hall were sifted through 25-?m-mesh sieve. Obtained dust fractions, P-25(I) collected near stove, rich in heavy metals and arsenic, and P-25(II) collected near anode residue storage site, rich in aluminium, were instilled to rats. At 1, 7 and 30 days after dusts instillation, lung injury and inflammation were measured by analyzing sings of lung permeability in the bronchoalveolar lavage fluid (BALF), cell differentiation in BALF sediment and lung morphology. The behavioral studies were done 30 days after exposure. Results of biochemical tests showed a strong pro-inflammatory effect of P-25(I) fractions. Mostly characteristic effects after instillation of P-25(I) samples were 10× increased protein leakages in BALF. Both P-25(I) and P-25(II) fractions caused a reduction of Clara-cell 16 protein concentration (CC16) in BALF and activation of serum butyrylcholinesterase (BChE) at all time points. The morphological studies after exposure to P-25(I) fractions showed multi-focal infiltrations in the alveoli. The behavioral results, especially P-25(II) group rats (in open filed, passive avoidance and hot plate tests), indicated adverse effects in the nervous system, which may be related to changes in the dopaminergic and cholinergic pathway. The symptoms were noted in the form of persistent neurobehavioral changes which might be associated with the content of neurotoxic metals. e.g. Al, Mn and/or As. Decrease of CC16 concentration that occurred immediately after instillation of both dust samples, point out impaired anti-inflammatory potential, resulted in early harmful effect not only to the respiratory tract but also to the whole body, including the nervous system.",
Arsenic,1579346,"The &quot;Strong&quot; RNA World Hypothesis: Fifty Years Old Abstract: This year marks the 50(th) anniversary of a proposal by Alex Rich that RNA, as a single biopolymer acting in two capacities, might have supported both genetics and catalysis at the origin of life. We review here both published and previously unreported experimental data that provide new perspectives on this old proposal. The new data include evidence that, in the presence of borate, small amounts of carbohydrates can fix large amounts of formaldehyde that are expected in an environment rich in carbon dioxide. Further, we consider other species, including arsenate, arsenite, phosphite, and germanate, that might replace phosphate as linkers in genetic biopolymers. While linkages involving these oxyanions are judged to be too unstable to support genetics on Earth, we consider the possibility that they might do so in colder semi-aqueous environments more exotic than those found on Earth, where cosolvents such as ammonia might prevent freezing at temperatures well below 273 K. These include the ammonia-water environments that are possibly present at low temperatures beneath the surface of Titan, Saturn's largest moon. Key Words: Astrobiology-Mineral adsorption-Origin of life-RNA world-Titan. Astrobiology 13, xxx-xxx.",
Arsenic,1020116,"Pharmacokinetic modeling of arsenite uptake and metabolism in hepatocytes--mechanistic insights and implications for further experiments Abstract: Arsenic (iAs) is a known human carcinogen and widespread contaminant in drinking water. To provide a quantitative framework for experimental design and hypothesis testing, we developed a pharmacokinetic model describing the uptake and methylation of arsenite (AsIII) in primary rat hepatocytes. Measured metabolites were inorganic As (iAs), mono-methylated As (MMA), and di-methylated As (DMA) concentration in cells and media. Transport and methylation parameters were estimated from time course data for iAs, MMA, and DMA at three initial media As(III) concentrations (0.1, 0.4, 1.0 microM). Inhibition of the formation DMA from MMA by As(III) was necessary to adequately describe the data. The data were consistent with multiple types of inhibition, although uncompetitive inhibition provided a slightly better fit. Model simulations indicate that cellular MMA (cMMA) is a key arsenical to measure; measurement of cMMA in the 4-6 hr time range using an initial concentration of 1.4 microM AsIII would provide the best experimental conditions to distinguish uncompetitive from other types of inhibition. Due to the large number of model parameters estimated from the data, we used sensitivity analysis to determine the influential parameters. Use of sensitivity surfaces facilitated the comparison of parameters over time and across doses. Predicted model responses were most sensitive to influx and efflux parameters, suggesting that transport processes are critical in determining cellular arsenical concentrations. These high sensitivities imply that independent experiments to estimate these parameters with greater certainty may be crucialfor refinement of this model and to extend this model to describe methylation and transport in human hepatocytes.",
Arsenic,1579311,"Differentiated dysplasia is a frequent precursor or associated lesion in invasive squamous cell carcinoma of the oral cavity and pharynx Abstract: The source of precursor lesions of squamous cell carcinoma (SCC) of the oral cavity and pharynx, their classification, and grading are controversial. In contrast, vulvar and penile cancer precursor lesions are known to be related to human papillomavirus or chronic inflammation and can be described using the vulvar intraepithelial neoplasia (VIN) classification system (VIN 1-3) or as differentiated vulvar intraepithelial neoplasia (dVIN), respectively. Oral and pharyngeal SCC precursor lesions are more etiologically diverse, and the spectrum of lesions may thus be wider. No international consensus exists regarding the histological types of precursor lesions or the significance of individual types. We therefore reviewed resection specimens and preceding biopsies of 155 patients with SCC of the oral cavity and pharynx (excluding tonsils) and identified five basic patterns of SCC-associated or precursor lesions: (1) pleomorphic (22/155), (2) basaloid (5/155), (3) differentiated (63/155), (4) mixed (42/155), and (5) verrucous (12/155). Keratinization was a common but variable feature in differentiated, mixed, and verrucous dysplasia. In 11/155 patients, no precursor lesion could be identified. Progression of isolated differentiated dysplasia (ranging from months to years) was documented in 13/155 (8 %) of patients. Our data suggest that full-thickness epithelial dysplasia of pleomorphic or basaloid type is present in &lt;20 % of oral and pharyngeal SCC, and differentiated dysplasia is a frequent precursor or associated in situ lesion. Failure to recognize differentiated dysplasia results in the underdiagnosis of many patients at risk for invasive carcinoma. These results indicate a need to refine criteria to distinguish differentiated dysplasia from morphologically related lichenoid lesions.",
Arsenic,627798,"Cdc42 regulates arsenic-induced NADPH oxidase activation and cell migration through actin filament reorganization Abstract: Although arsenic is a human carcinogen, the molecular mechanisms of its action remain to be understood. The present study reports that exposure to arsenic induced actin filament reorganization, resulting in lamellipodia and filopodia structures through the activation of Cdc42 in SVEC4-10 endothelial cells. It was also found that arsenic induced the formation of the superoxide anion (O2*) in SVEC4-10 cells. Immunoprecipitation and Western blotting analysis demonstrated that arsenic stimulation induced serine phosphorylation of p47phox, a key component of NADPH oxidase, indicating that arsenic induces O2* formation through NADPH oxidase activation. Inhibition of arsenic-induced actin filament reorganization by either overexpression of a dominant negative Cdc42 or pretreatment of an actin filament stabilizing regent, jasplakinolide, abrogated arsenic-induced NADPH oxidase activation, showing that the activation of NADPH oxidase was regulated by Cdc42-mediated actin filament reorganization. This study also showed that overexpression of a dominant negative Rac1 was sufficient to abolish arsenic-induced O2*- production, implying that Rac1 activities are required for Cdc42-mediated NADPH oxidase activation in response to arsenic stimulation. Furthermore, arsenic stimulation induced cell migration, which can be inhibited by the inactivation of either Cdc42 or NADPH oxidase. Taken together, the results indicate that arsenic is able to activate NADPH oxidase through Cdc42-mediated actin filament reorganization, leading to the induction of an increase in cell migration in SVEC4-10 endothelial cells.",
Arsenic,1508585,"Estimation of autistic children by metallomics analysis Abstract: Clarification of the pathogenesis and treatment of autism spectrum disorders is one of the challenges today. In this study, we examine scalp hair concentrations of 26 trace elements for 1,967 children with autistic disorders (1,553 males and 414 females). Five-hundred and eighty-four (29.7%), 347 (17.6%) and 114 (5.8%) subjects was found deficient in zinc, magnesium and calcium, respectively, and 2.0% or less in the other essential metals. The incidence rate of mineral deficiency was highly observed in infants aged 0-3 year-old. In contrast, 339 (17.2%), 168 (8.5%) and 94 (4.8%) individuals was found suffering from high burden of aluminium, cadmium and lead, and 2.8% or less from mercury and arsenic burden. These findings suggest that infantile zinc- and magnesium-deficiency and/or toxic metal burdens may epigenetically play principal roles as environmental factors in autistic disorders and that metallomics approach may lead to early screening and prevention of the neurodevelopment disorders.",
Arsenic,1346047,"The behavior of arsenic and antimony at Pezinok mining site, southwestern part of the Slovak Republic Abstract: ",
Arsenic,1026282,"Sodium arsenite modulates histone acetylation, histone deacetylase activity and HMGN protein dynamics in human cells Abstract: Extensive epidemiological data indicate that inorganic arsenic is associated with several types of human cancer. Nevertheless, the underlying mechanisms are poorly understood. Among its mode of action are the alterations on DNA methylation, which provoke aberrant gene expression. However, beyond DNA methylation, little is known about arsenic's effects on chromatin. In this study, we investigated the effects of sodium arsenite (NaAsO(2)) on global histone modifications and nucleosome-associated proteins. Our findings revealed that NaAsO(2) exposure significantly increases global histone acetylation. This effect was related to the inhibition of histone deacetylase (HDAC) activity because NaAsO(2) was able to inhibit HDACs comparable to the well-known HDAC inhibitor trichostatin A (TSA). Furthermore, analyses of the dynamic properties of the nucleosome-associated high mobility group N proteins demonstrate that NaAsO(2) elevates their mobility. Thus, our data suggest that NaAsO(2) induces chromatin opening by histone hyperacetylation due to HDAC inhibition and increase of the mobility of nucleosome-associated proteins. As the chromatin compaction is crucial for the regulation of gene expression as well as for genome stability, we propose that chromatin opening by NaAsO(2) may play a significant role to impart its genotoxic effects.",
Arsenic,2064225,"Mineral nutrition and enzymatic adaptation induced by arsenate and arsenite exposure in lettuce plants Abstract: Arsenate (As(V)) and arsenite (As(III)) contamination is able to interfere negatively on plant metabolism, promoting a reduction of nutrients uptake and transport and also an increase of reactive oxygen species (ROS) generation. However, some plants are considered tolerant against As exposure through the activation of defense mechanisms. Therefore, this study aimed to evaluate the effects of different As(V) and As(III) concentrations (0.0, 6.6, 13.2, 26.4 and 52.8 ?mol L(-1)), on mineral nutrients concentration [calcium (Ca), magnesium (Mg), phosphorous (P), iron (Fe), manganese (Mg) and copper (Cu)], on membrane lipid peroxidation and also on the enzymes belonging to the antioxidant defense system [superoxide dismutase (SOD), total peroxidase (POX), catalase (CAT), glutathione reductase (GR) and ascorbate peroxidase (APX)] of plants of Lactuca sativa L. cv Hanson. As(V) and As(III), showed, in general, the same toxic effects in leaves and roots with significant changes in essential macro- and micronutrients concentration. Lipid peroxidation of cellular membranes was also observed in tested plants, probably resulted from an action of ROS generated by this metalloid. The increase of ROS generation and their scavenge were evident since an increase of SOD, POX, CAT and APX activity in leaves, and SOD, CAT and GR activity in roots were observed. Therefore, As(V) and As(III) exposure resulted in toxic effects in leaves and roots of lettuce plants; however, this plant species was able to attenuate these potential As damages through the activation of defense mechanisms, keeping its metabolism. Arsenic-tolerant plants are considered a great risk to the public health since it results in As insertion to the food chain.",
Arsenic,1508675,"Antipyrine based arsenate selective fluorescent probe for living cell imaging Abstract: Condensation of salicylaldehyde and 4-aminoantipyrine has yielded a new fluorescent probe (APSAL) capable of detecting intracellular arsenate at the micromolar level for the first time. The structure of the probe has been established by different spectroscopic techniques and confirmed from X-ray crystallography. Common anions, viz., F(-), Cl(-), Br(-), I(-), N(3)(-), NCO(-), NO(2)(-), NO(3)(-), SCN(-), CN(-), CH(3)COO(-), SO(4)(2-), ClO(4)(-), and HPO(4)(2-) do not interfere. The binding constant of APSAL for H(2)AsO(4)(-) has been determined using the Benesi-Hildebrand equation as 8.9 × 10(3) M(-1). Fluorescence quantum yield of APSAL (0.016) increases more than 12 times upon binding arsenate ion.",
Arsenic,710849,"Arsenic-induced QT dispersion is associated with atherosclerotic diseases and predicts long-term cardiovascular mortality in subjects with previous exposure to arsenic: A 17-Year follow-up study Abstract: Chronic arsenic poisoning is a major worldwide public health problem. Recently, we had reported chronic arsenic poisoning was dose-dependently associated with ventricular abnormalities quantified by electrocardiographic QT prolongation linking to atherosclerotic diseases. An association of chronic arsenic poisoning with ventricular repolarization inhomogeneity quantified by QT dispersion (QTD) is of particular interest from a theoretical and practical perspective. We aimed to further elucidate (1) the association of chronic arsenic exposure with ventricular abnormalities quantified by QTD, (2) the association of QTD with atherosclerotic diseases and (3) the predictability of QTD for long-term mortality in subjects with chronic arsenic poisoning. We followed up 280 men and 355 women living in arseniasis-endemic area in southwestern coast in Taiwan for 17 years. QTD in electrocardiogram and carotid intima-media thickness by ultrasonography were measured. Coronary artery disease was diagnosed by an abnormal electrocardiogram and a definite history. Cumulative arsenic exposure was significantly associated with QTD showing a dose-response relationship (P &lt; 0.001). Significant associations of the QTD with coronary artery disease and carotid atherosclerosis existed after adjustment for potential confounders in the multiple linear regression analysis (all P values &lt; 0.05). In the multivariate Cox regression analyses, the hazard ratios (95% confidence interval, P value) of cumulative cardiovascular and all-cause mortality were 3.9 (2.1-6.2, P = 0.002) and 1.4 (0.9-2.3, P = 0.10), respectively, for QTD &gt; or = 65 ms compared with QTD &lt; 65. QTD may be indicated as an early biomarker for atherosclerotic diseases and a significant and strong predictor of cardiovascular mortality in population with chronic arsenic exposure.",
Arsenic,1340116,"Biosorption of arsenic from aqueous solution using dye waste Abstract: The purpose of this study is to examine on removal of arsenic from water by biosorption through potential application of herbal dye wastes. Four different flower dye residues (after extraction of natural dye) viz. Hibiscus rosasinensis, Rosa rosa, Tagetes erecta, and Canna indica were utilized successfully for the removal of arsenic from aqueous solution. Batch studies were carried out for various parameters viz. pH, sorbent dose, contact time, initial metal ion concentration, and temperature. Data were utilized for isothermal, kinetic, and thermodynamic studies. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDAX), and Fourier transform infrared (FTIR) analyses of biomass were performed. The results showed that 1 g/100 ml for 5.0-5.5 h contact time at pH 6.0-7.5 with agitation rate 150 rpm provided 98, 96, 92, and 85 % maximum absorption of arsenic by R. rosa, H. rosasinensis, T. erecta, and C. indica, respectively, at initial concentration of 500 ppb. Data followed Langmuir isotherm showing sorption to be monolayer on heterogeneous surface of biosorbent. Negative values of ?G° indicated spontaneous nature, whereas ?H° indicates exothermic nature of system followed by pseudo-first-order adsorption kinetics. FTIR results showed apparent changes in functional group regions after metal chelation. SEM and EDAX analyses showed the changes in surface morphology of all test biosorbents. Herbal dye wastes, used as biosorbent, exhibited significant (85-98 %) removal of arsenic from aqueous solution. Hence, these biosorbents are cost-effective, easily available, eco-friendly, and comparatively more effective than other biosorbents already in use. These may be used to remove arsenic and other toxic metals from water.",
Arsenic,1508704,"A baseline study of levels of mercury, arsenic, cadmium and lead in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea Abstract: This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and liver of more than 800 Northeast Arctic cod caught at 32 sites in the Barents Sea are reported. The highest concentration of both mercury in the muscle and cadmium in the liver was found in cod caught in the western part of the Barents Sea, while the highest concentration of total arsenic was found in cod from the eastern part. The arsenic concentrations varied greatly among individual fish, ranging from 0.3 to 170mgkg(-1) wet weight in the muscle. Such high levels of total arsenic have never previously been reported in any fish, and the primary factor for these high concentrations is likely to be the shrimp in the cod diet.",
Arsenic,1029249,"Effects of simultaneous repeated exposure at high levels of arsenic and malathion on hepatic drug-biotransforming enzymes in broiler chickens Abstract: Groundwater contamination with arsenic is a major global health concern. The organophosphorus insecticide malathion has gained significance as an environmental pollutant due to its widespread use in agriculture, grain storage, ectoparasite control and public health management. The deleterious effects produced by arsenic or malathion alone are documented, but very little is known about the consequences of their coexposure. The aim of the current study was to examine the effects of repeated simultaneous exposure to arsenic and malathion on drug-biotransforming enzymes in the liver of broiler chickens. One-month-old broiler chickens were exposed daily to arsenic (50 ppm)-supplemented drinking water, malathion (500 ppm)-mixed diet or in a similar fashion coexposed to these agents for 28 days. At the term, changes in body weight, organ weights, and levels of hepatic cytochrome P450 (CYP), cytochrome b(5), microsomal and cytosolic proteins; aminopyrine N-demethylase (ANDM), aniline P-hydroxylase (APH), glutathione S-transferase (GST) and uridine diphosphate glucuronosyltransferase (UGT) were assessed. Arsenic, malathion or their coexposure decreased the body weight gain and liver weight. Brain weight (relative) was increased with arsenic or malathion, but not with the coexposure. Treatment with arsenic decreased the CYP and cytochrome b(5) contents by 39 and 36%, than with malathion by 54 and 22% and the coexposure by 45 and 28%, respectively. The ANDM activity was decreased with arsenic (44%), malathion (23%) and the coexposure (32%). Arsenic (23%) and the coexposure (37%), but not malathion (14%), reduced the APH activity. The activities of hepatic microsomal and cytosolic GST were increased with all the three treatments [Arsenic (microsomal: 88% cytosolic: 113%), malathion (microsomal: 137%, cytosolic: 94%) and coexposure (microsomal: 140%, cytosolic: 148%)]. These treatments did not significantly affect the hepatic UGT activity, but reduced the hepatic microsomal (arsenic: 28%, malathion: 34% and coexposure: 43%) and cytosolic (17-19%) protein contents. The effects of coexposure on the activities of various phase I and phase II drug-biotransforming enzymes were almost similar to that of arsenic or malathion. This study provides evidence that repeated coexposure to arsenic and malathion may influence the extent of drug metabolism in chickens.",
Arsenic,2337088,"Reduced Antimony Accumulation in ARM58-Overexpressing Leishmania infantum Abstract: Antimony-based drugs are still the mainstay of chemotherapy against Leishmania infections in many countries where the parasites are endemic. The efficacy of antimonials has been compromised by increasing numbers of resistant infections, the basis of which is not fully understood and likely involves multiple factors. By using a functional cloning strategy, we recently identified a novel antimony resistance marker, ARM58, from the parasite Leishmania braziliensis that protects the parasites against antimony-based antileishmanial compounds. Here we show that the Leishmania infantum homologue also confers resistance against antimony but not against other antileishmanial drugs and that its function depends critically on one of four conserved domains of unknown function. This critical domain requires at least two hydrophobic amino acids and is predicted to form a transmembrane structure. Overexpression of ARM58 in antimony-exposed parasites reduces the intracellular Sb accumulation by over 70%, indicating a role for ARM58 in Sb extrusion pathways, but without involvement of energy-dependent transporter proteins.",
Arsenic,1017850,"Protective effect of Corchorus olitorius leaves against arsenic-induced oxidative stress in rat brain Abstract: The present study was undertaken to evaluate the protective effect of an aqueous extract of Corchorus olitorius leaves (AECO) against NaAsO(2) induced brain toxicity in experimental rats. The animals exposed to NaAsO(2) (10mg/kg, p.o.) for 10 days exhibited a significant inhibition (p&lt;0.01) of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase and reduced glutathione levels in rat brain. In addition, the toxin increased (p&lt;0.01) the levels of oxidized glutathione and thiobarbituric acid reactive substances in the brain tissue of experimental rats. Treatment with AECO (50 and 100mg/kg, p.o.) for 15 days prior to arsenic intoxication significantly improved antioxidant markers in a dose dependant manner. Histological studies on the ultrastructural changes of brain tissue supported the protective activity of the AECO. The results suggest that treatment with AECO prior to arsenic intoxication has a significant role in protecting animals from arsenic-induced toxicity.",
Arsenic,2347734,"Assessment of groundwater quality with special reference to arsenic in Nawalparasi district, Nepal using multivariate statistical techniques Abstract: Groundwater is a precious resource for humankind not only in Nepal but also across the globe due to its diverse functions. A total of 48 groundwater samples were collected from three villages of Nawalparasi district, Nepal, during pre-monsoon and monsoon to estimate the overall groundwater quality and to identify the sources of contamination with emphasis on arsenic (As). The average concentrations of all tested groundwater quality parameters (temp., pH, EC, ORP, Ca2+, Mg2+, Na+, K+, Cl-, F-,SO4 (2-), PO4 (3-), HCO3 (-), NO3 (-), Cu, Ni, Mn, Cd, Pb, Fe, Zn, Cr, and As) were well within permissible limits of WHO for drinking water, except for Ni, Cd, Pb, Cr, and As. Concentration of As ranged from 60 to 3,100 mu g L-1 and 155 to 1,338 mu g L-1 in pre-monsoon and monsoon, respectively. The Piper diagram of the groundwater chemistry showed groundwater of Nawalparasi belongs to Ca-Mg-HCO3 and Mg-HCO3 water type with HCO3 (-) as dominant ions. As content in the study area was negatively correlated with Fe in pre-monsoon, while it was positively correlated in monsoon. Furthermore, As was negatively correlated with oxidation reduction potential suggesting reducing condition of groundwater. Principal component analysis revealed seven major factors that explained 81.996 and 83.763 % of total variance in water quality in pre-monsoon and monsoon, respectively. The variance of water quality was related mainly with the degree of water-rock interaction, mineralization, and anthropogenic inputs.",
Arsenic,1347391,"Sodium arsenite downregulates transcriptional activity of AP-1 and CRE binding proteins in IL-1 beta-treated Caco-2 cells by increasing the expression of the transcriptional repressor CREM alpha Abstract: In recent studies, sodium arsenite (SA) inhibited IL-6 production in cultured intestinal epithelial cells, at least in part by downregulating the activity of nuclear factor-kappaB (NF-kappaB). The influence of SA on the activity of other transcription factors regulating the interleukin-6 (IL-6) gene in enterocytes is not known. We tested the effect of SA on the activity of CCAAT/enhancer binding protein (C/EBP), activating protein-1 (AP-1), and CRE binding proteins in IL-1beta-treated Caco-2 cells. DNA binding activity was determined by electrophoretic mobility shift assay (EMSA) and transcriptional activity by transfecting cells with luciferase reporter plasmids containing promoter constructs with binding sites for the individual transcription factors. DNA binding activity for all three transcription factors was increased after treatment with SA or IL-1beta. In contrast, SA inhibited transcriptional activity of AP-1 and CRE binding proteins but not C/EBP. Additional experiments provided evidence that the inhibition of AP-1 and CRE mediated transcriptional activity was associated with, and probably caused by, increased expression of the transcriptional repressor cyclic AMP response element modulator (CREM)alpha. The present results are consistent with the concept that SA inhibits IL-6 production in stimulated enterocytes by downregulating the transcriptional activity of several, but not all, IL-6-related transcription factors. Because of the multiple important biological functions of IL-6 in the enterocyte and gut mucosa, methods to regulate enterocyte IL-6 production have significant clinical implications.",
Arsenic,627050,"Differential activation of AP-1 in human bladder epithelial cells by inorganic and methylated arsenicals Abstract: Chronic exposures to inorganic arsenic (iAs) have been linked to increased incidences of various cancers, including cancer of the urinary bladder. Mechanisms by which iAs promotes cancer may include stimulation of activator protein-1 (AP-1) DNA binding through increased expression and/or phosphorylation of the AP-1 constituents. However, the role of methylated metabolites of iAs in AP-1 activation has not been thoroughly examined. In this study, we show that short-time exposures to 0.1-5 microM arsenite (iAsIII) or the methylated trivalent arsenicals methylarsine oxide (MAsIIIO), or iododimethylarsine (DMAsIIII) induce phosphorylation of c-Jun and increase AP-1 DNA binding activity in human bladder epithelial cells. DMAsIIII and especially MAsIIIO are considerably more potent than iAsIII as inducers of c-Jun phosphorylation and AP-1 activation. Phosphorylated c-Jun, JunB, JunD, and Fra-1, but not c-Fos, FosB, or ATF-2, are detected in the AP-1-DNA binding complex in cells exposed to trivalent arsenicals. In cells transiently transfected with an AP-1-dependent promoter-reporter construct, MAsIIIO was more potent than iAsIII in inducing the AP-1-dependent gene transcription. Exposures to trivalent arsenicals induce phosphorylation of extracellular signal-regulated kinase (ERK), but not c-Jun N-terminal kinases or p38 kinases. These results indicate that an ERK-dependent signal transduction pathway is at least partially responsible for c-Jun phosphorylation and AP-1 activation in UROtsa cells exposed to inorganic or methylated trivalent arsenicals.",
Arsenic,710965,"Inorganic arsenic modulates the expression of selenoproteins in mouse embryonic stem cell Abstract: At least 25 selenoproteins in humans and 24 homologues in rodents have been identified. They play important roles in antioxidation, redox regulation and detoxification. The modulation of the expression of selenoproteins by inorganic arsenic (iAs) exposure may highlight the molecular mechanism for the arsenic toxicity. To investigate the effects of iAs exposure on the expression of selenoproteins, we determined how addition of iAs to culture medium affected all known selenoproteins in the mouse embryonic stem (ES) cells. Separated groups of ES cells were treated with arsenite (iAsIII) (0.25-0.5microM), arsenate (iAsV) (1.0-2.0microM) and co-treatment with sodium selenite (SeIV) (0.5microM). The mRNA levels of all selenoproteins were detected by real time quantitative PCR. The up-regulated selenoproteins were confirmed by immunoblotting analysis and enzymatic activity detection. Results showed that CGR8 cells treated with iAsIII (0.25-0.5microM) and iAsV (2.0microM) displayed significant increases of cellular reactive oxygen species (ROS) generation and nuclear accumulation of the transcription factor NF-E2-related factor 2 (Nrf2). Treatments of iAsIII (0.5microM) or iAsV (2.0microM) for 24h caused significant increases in the expression of the antioxidant selenoproteins (Gpx1, Gpx4, and Tr1), whereas led to significant decreases in the mRNA levels of selenoprotein H and some endoplasmic reticulum (ER) located selenoproteins (15-Sep, SelK, SelM, and SelS). Additionally, supplement of SeIV (0.5microM) could restore most of the down-regulated selenoproteins. These results suggested that iAs exposure modulated not only the antioxidant selenoproteins but also the ER stress associated selenoproteins. Further studies are required to clarify whether these modulated selenoproteins genes are targets for selenium supplement in the defense against the toxicity of iAs.",
Arsenic,1016359,"Arsenic-induced cell proliferation is associated with enhanced ROS generation, Erk signaling and CyclinA expression Abstract: Arsenic is a well-established human carcinogen; however molecular mechanisms to arsenic-induced carcinogenesis are complex and elusive. The present study identifies a potential biomarker of arsenic exposure, and redefines arsenic-induced signaling in stimulation of cell proliferation. The effect of arsenic exposure on gene expression was evaluated in PBMC of arsenic-exposed individuals selected from a severely affected district of West Bengal, India. A novel, un-documented biomarker of arsenic exposure, CyclinA was identified by microarray analysis from the study. Non-transformed cell lines HaCat and Int407 when exposed to clinically achievable arsenic concentration showed significant increase of CyclinA substantiating the clinical data. An associated increase in S phase population of cells in cell cycle, indicative of enhanced proliferation was also noticed. On further investigation of the pathway to arsenic-induced proliferation, we observed that arsenic resulted: ROS generation; activated Erk signaling; stimulated AP-1 activity, including immediate early genes, c-Jun and c-Fos. N-Acetyl-l-cysteine, a ROS quencher, blocked the arsenic-induced effects. Our study underlines a previously undefined mechanism by which arsenic imparts its toxicity and results in uncontrolled cell proliferation.",
Arsenic,1030111,"Massive arsenic poisoning--effect of hemodialysis and dimercaprol on arsenic kinetics Abstract: In massive arsenic poisoning, the use of hemodialysis and dimercaprol (BAL) therapy is still controversial. Hemodialysis is thought of value only for supportive care. BAL therapy has been criticized because of its delayed action, its own toxicity and its possible influence on arsenic clearance during hemodialysis. We studied arsenic kinetics during an acute suicidal intoxication (10 g of sodium arsenate). Treatment included gastric lavage, oral charcoal and supportive measures. Hemodialysis was performed immediately and repeated the next day. BAL therapy was prescribed only on the second day. Cardiovascular collapse, anuria and hepatic disturbance recovered in a few days and the patient could be discharged on the 15th day. Instantaneous serum arsenic hemodialysis clearance was 85 +/- 75 ml/min without previous BAL injection and 87.5 +/- 75 ml/min with a previous 250 mg BAL injection (difference not significant) indicating that BAL did not impede arsenic dialysis. The calculated total hemodialysis clearance of arsenic was higher than mean serum hemodialysis clearance indicating that erythrocyte bound arsenic is also eliminated during dialysis. We propose to consider early hemodialysis as an elimination measure in massive arsenic poisoning and to choose BAL as a chelator when dialysis is required.",
Arsenic,1015705,"Genome-wide association study identifies chromosome 10q24.32 variants associated with arsenic metabolism and toxicity phenotypes in bangladesh Abstract: Arsenic contamination of drinking water is a major public health issue in many countries, increasing risk for a wide array of diseases, including cancer. There is inter-individual variation in arsenic metabolism efficiency and susceptibility to arsenic toxicity; however, the basis of this variation is not well understood. Here, we have performed the first genome-wide association study (GWAS) of arsenic-related metabolism and toxicity phenotypes to improve our understanding of the mechanisms by which arsenic affects health. Using data on urinary arsenic metabolite concentrations and approximately 300,000 genome-wide single nucleotide polymorphisms (SNPs) for 1,313 arsenic-exposed Bangladeshi individuals, we identified genome-wide significant association signals (P&lt;5×10(-8)) for percentages of both monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) near the AS3MT gene (arsenite methyltransferase; 10q24.32), with five genetic variants showing independent associations. In a follow-up analysis of 1,085 individuals with arsenic-induced premalignant skin lesions (the classical sign of arsenic toxicity) and 1,794 controls, we show that one of these five variants (rs9527) is also associated with skin lesion risk (P?=?0.0005). Using a subset of individuals with prospectively measured arsenic (n?=?769), we show that rs9527 interacts with arsenic to influence incident skin lesion risk (P?=?0.01). Expression quantitative trait locus (eQTL) analyses of genome-wide expression data from 950 individual's lymphocyte RNA suggest that several of our lead SNPs represent cis-eQTLs for AS3MT (P?=?10(-12)) and neighboring gene C10orf32 (P?=?10(-44)), which are involved in C10orf32-AS3MT read-through transcription. This is the largest and most comprehensive genomic investigation of arsenic metabolism and toxicity to date, the only GWAS of any arsenic-related trait, and the first study to implicate 10q24.32 variants in both arsenic metabolism and arsenical skin lesion risk. The observed patterns of associations suggest that MMA% and DMA% have distinct genetic determinants and support the hypothesis that DMA is the less toxic of these two methylated arsenic species. These results have potential translational implications for the prevention and treatment of arsenic-associated toxicities worldwide.",1
Arsenic,1016149,"Estimation of a method detection limit for an in vivo XRF arsenic detection system Abstract: An x-ray fluorescence measurement system has been developed with an 125I source to detect arsenic in superficial layers of phantoms and tissue. Based on in vivo measurements, in conjunction with Monte Carlo simulations, the detection limit for arsenic in skin ranges between 2.6+/-0.5 and 5.7+/-1.1 microg g(-1), depending on skin thickness and assuming that arsenic is uniformly distributed in the skin. The effect of skin arsenic distribution was also examined.",
Arsenic,1018549,"Effect of arsenite on urea production by long-term cultures of adult rat hepatocytes Abstract: Urea cycle is a hepatic metabolic pathway involving five enzymes and several intermediary metabolites and can be altered by different chemicals. To investigate the effect of arsenic, an ubiquitous hepatotoxic agent, on urea production we exposed long-term cultures of adult rat hepatocytes, which produce urea, to 1.33 and 6.67 microM arsenite for 2 weeks. In cultures exposed to 6.67 microM, urea production decreased 60-70% and cellular arginase activity decreased 30, 70 and 85% after 4, 7 and 14 days of exposure, respectively. The arginase activity released to the medium increased significantly after 4, 7 and 14 days, with a maximum value after 7 days of exposure that was 27-fold higher than that of the untreated controls. The total arginase activity also decreased 35, 52 and 82% after 4, 7 and 14 days of exposure and protein content decreased 57 and 65% after 7 and 14 days of exposure, respectively. Exposure to 6.67 microM arsenite also produced accumulation of intracytoplasmic lipid droplets, vacuolizations and enlargement of the intercellular spaces. On the other hand, exposure of hepatocytes to 1.33 microM arsenite caused an initial decrease of 20% in urea production, did not change cellular, released and total arginase activity and cellular protein content and produced accumulation of intracytoplasmic lipid droplets. These results show that long-term exposure of cultured rat hepatocytes to 6.67 microM arsenite decreases urea production, cellular and total arginase activity and protein content and increases the release of arginase into the culture medium. These alterations could be useful markers of hepatotoxicity in in vitro assays.",
Arsenic,1240290,"Potential pollutant sources in a Choptank River (USA) subwatershed and the influence of land use and watershed characteristics Abstract: Row-crop and poultry production have been implicated as sources of water pollution along the Choptank River, an estuary and tributary of the Chesapeake Bay. This study examined the effects of land use, subwatershed characteristics, and climatic conditions on the water quality parameters of a subwatershed in the Choptank River watershed. The catchments within the subwatershed were defined using advanced remotely-sensed data and current geographic information system processing techniques. Water and sediment samples were collected in May-October 2009 and April-June 2010 under mostly baseflow conditions and analyzed for select bacteria, nitrate-N, ammonium-N, total arsenic, total phosphorus (TP), orthophosphate (ortho-P), and particle-phase phosphorus (PP); n=96 for all analytes except for arsenic, n=136, and for bacteria, n=89 (aqueous) and 62 (sediment). Detections of Enterococci and Escherichia coli concentrations were ubiquitous in this subwatershed and showed no correlation to location or land use, however larger bacterial counts were observed shortly after precipitation. Nitrate-N concentrations were not correlated with agricultural lands, which may reflect the small change in percent agriculture and/or the similarity of agronomic practices and crops produced between catchments. Concentration data suggested that ammonia emission and possible deposition to surface waters occurred and that these processes may be influenced by local agronomic practices and climatic conditions. The negative correlation of PP and arsenic concentrations with percent forest was explained by the stronger signal of the head waters and overland flow of particulate phase analytes versus dissolved phase inputs from groundwater. Service roadways at some poultry production facilities were found to redirect runoff from the facilities to neighboring catchment areas, which affected water quality parameters. Results suggest that in this subwatershed, catchments with poultry production facilities are possible sources for arsenic and PP as compared to catchment areas where these facilities were not present.",
Arsenic,1019529,"Altered activity of heme biosynthesis pathway enzymes in individuals chronically exposed to arsenic in Mexico Abstract: Our objective was to evaluate the activities of some enzymes of the heme biosynthesis pathway and their relationship with the profile of urinary porphyrin excretion in individuals exposed chronically to arsenic (As) via drinking water in Region Lagunera, Mexico. We selected 17 individuals from each village studied: Benito Juarez, which has current exposure to 0.3 mg As/l; Santa Ana, where individuals have been exposed for more than 35 years to 0.4 mg As/l, but due to changes in the water supply (in 1992) exposure was reduced to its current level (0.1 mg As/l), and Nazareno, with 0.014 mg As/l. Average arsenic concentrations in urine were 2058, 398, and 88 microg As/g creatinine, respectively. The more evident alterations in heme metabolism observed in the highly exposed individuals were: (1) small but significant increases in porphobilinogen deaminase (PBG-D) and uroporphyrinogen decarboxylase (URO-D) activities in peripheral blood erythrocytes; (2) increases in the urinary excretion of total porphyrins, mainly due to coproporphyrin III (COPROIII) and uroporphyrin III (UROIII); and (3) increases in the COPRO/URO and COPROIII/COPROI ratios. No significant changes were observed in uroporphyrinogen III synthetase (UROIII-S) activity. The direct relationships between enzyme activities and urinary porphyrins, suggest that the increased porphyrin excretion was related to PBG-D, whereas the increased URO-D activity would enhance coproporphyrin synthesis and excretion at the expense of uroporphyrin. None of the human studies available have reported the marked porphyric response and enzyme inhibition observed in rodents. In conclusion, chronic As exposure alters human heme metabolism; however the severity of the effects appears to depend on characteristics of exposure not yet fully characterized.",
Arsenic,1017369,"Occupational exposure to arsenic, cadmium, chromium, lead and nickel, and renal cell carcinoma: A case-control study from Central and Eastern Europe Abstract: <strong>OBJECTIVES: </strong>To investigate the risk of renal cell carcinoma (RCC) in Central and Eastern Europe in relation to exposure to known and suspected carcinogenic metals.<br /><br /><strong>METHODS: </strong>During 1999-2003, the authors conducted a hospital-based study in Czech Republic, Poland, Romania and Russia, including 1097 cases of RCC and 1476 controls. Occupational exposure to arsenic, cadmium, chromium(III), chromium(VI), lead and nickel was assessed by teams of local industrial hygiene experts, based on detailed occupational questionnaires.<br /><br /><strong>RESULTS: </strong>The ORs for RCC were 1.55 (95% CI 1.09 to 2.21) for exposure to lead and 1.40 (95% CI 0.69 to 2.85) for exposure to cadmium. No clear monotonic exposure-response relation was apparent for either duration of exposure or cumulative exposure to either metal, although the OR for the highest category of cumulative exposure to lead was 2.25 (95% CI 1.21 to 4.19). Exposure to other metals did not entail an increased risk of RCC.<br /><br /><strong>CONCLUSIONS: </strong>For cadmium, the lack of statistical significance of most results, potential confounding and the absence of clear dose-response relations suggest that an association with RCC is unlikely to be causal. In the case of lead, however, the elevated risk in the category of highest cumulative exposure is noteworthy and justifies further investigation.",
Arsenic,1797818,"Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks Abstract: Pregnant women in Africa, Asia and Suriname, and some immigrants in Western societies, traditionally consume clay products known by a variety of names such as mabele, calabash chalk, sikor and pimba. Furthermore, clay is used for health purposes in Western societies. Because certain clays can contain high levels of metals and metalloids, the aim of this study was to determine lead, arsenic, mercury and cadmium in clay products for oral use available on the Dutch market. Traditional clays originating from Africa (n = 10) and Suriname (n = 26), and health clays (n = 27) were sampled from 2004 up to and including 2012. Total metal and metalloid contents were measured by ICP-MS and showed maximum levels of lead, arsenic, mercury and cadmium of 99.7, 45.1, 2.2 and 0.75 mg kg(-1), respectively. In the absence of maximum limits for these type of clays, the potential exposure was estimated from the determined concentration, the estimated daily use level of the clays, and the estimated bioaccessibility of the different metals and arsenic. The intake estimates were compared with existing health-based guidance values. For lead, the use of 34 of the 36 traditional clays and two of the 27 health clays would result in intake levels exceeding the toxicological limit by up to 20-fold. Use of 15 of the 35 traditional clays and 11 of the 27 health clays would result in intake levels exceeding the toxicological limit for inorganic arsenic by up to 19-fold. Although limited bioaccessibility from the clay may limit the exposure and exceedance of the health-based guidance values, it was concluded that lead and arsenic intakes from some clay products could be of concern also because of their use by pregnant women and the potential developmental toxicity. As a result the use of these products, especially by pregnant women, should be discouraged.",
Arsenic,2278450,"The use of olive-mill waste compost to promote the plant vegetation cover in a trace-element-contaminated soil Abstract: The applicability of a mature compost as a soil amendment to promote the growth of native species for the phytorestoration of a mine-affected soil from a semi-arid area (SE Spain), contaminated with trace elements (As, Cd, Cu, Mn, Pb and Zn), was evaluated in a 2-year field experiment. The effects of an inorganic fertiliser were also determined for comparison. Bituminaria bituminosa was the selected native plant since it is a leguminous species adapted to the particular local pedoclimatic conditions. Compost addition increased total organic-C concentrations in soil with respect to the control and fertiliser treatments, maintained elevated available P concentrations throughout the duration of the experiment and stimulated soil microbial biomass, while trace elements extractability in the soil was rather low due to the calcareous nature of the soil and almost unaltered in the different treatments. Tissue concentrations of P and K in B. bituminosa increased after the addition of compost, associated with growth stimulation. Leaf Cu concentration was also increased by the amendments, although overall the trace elements concentrations can be considered non-toxic. In addition, the spontaneous colonisation of the plots by a total of 29 species of 15 different families at the end of the experiment produced a greater vegetation cover, especially in plots amended with compost. Therefore, the use of compost as a soil amendment appears to be useful for the promotion of a vegetation cover and the phytostabilisation of moderately contaminated soils under semi-arid conditions.",
Arsenic,2088503,"Arsenic augments the uptake of oxidized LDL by upregulating the expression of lectin-like oxidized LDL receptor in mouse aortic endothelial cells Abstract: Although chronic arsenic exposure is a well-known risk factor for cardiovascular diseases, including atherosclerosis, the molecular mechanism underlying arsenic-induced atherosclerosis remains obscure. Therefore, this study aimed to elucidate this molecular mechanism. We examined changes in the mRNA level of the lectin-like oxidized LDL (oxLDL) receptor (LOX-1) in a mouse aortic endothelial cell line, END-D, after sodium arsenite (SA) treatment. SA treatment significantly upregulated LOX-1 mRNA expression; this finding was also verified at the protein expression level. Flow cytometry and fluorescence microscopy analyses showed that the cellular uptake of fluorescence (Dil)-labeled oxLDL was significantly augmented with SA treatment. In addition, an anti-LOX-1 antibody completely abrogated the augmented uptake of Dil-oxLDL. We observed that SA increased the levels of the phosphorylated forms of nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-?B)/p65. SA-induced upregulation of LOX-1 protein expression was clearly prevented by treatment with an antioxidant, N-acetylcysteine (NAC), or an NF-?B inhibitor, caffeic acid phenethylester (CAPE). Furthermore, SA-augmented uptake of Dil-oxLDL was also prevented by treatment with NAC or CAPE. Taken together, our results indicate that arsenic upregulates LOX-1 expression through the reactive oxygen species-mediated NF-?B signaling pathway, followed by augmented cellular oxLDL uptake, thus highlighting a critical role of the aberrant LOX-1 signaling pathway in the pathogenesis of arsenic-induced atherosclerosis.",
Arsenic,1018180,"Time-period mortality patterns in a gaseous diffusion plant workforce Abstract: <strong>BACKGROUND: </strong>We sub-divided a cohort of 6820 workers at the Paducah (KY) Gaseous Diffusion Plant (PGDP) which was traced from 1953 to 2003. The subdivisions were made to assess the mortality risks in a sub-group of workers employed solely during the plant's refit period, a time of suspected higher exposure to metal dusts (nickel, arsenic, chromium and uranium) and trichloroethylene.<br /><br /><strong>METHODS: </strong>This article describes a comparison of exposures and causes of death for 754 workers employed exclusively during the period of 1975-1979, with 1554 workers who worked in this period as well as other years. This interval was when the gaseous diffusion cascade facilities were re-fit. The workers employed 'only' during this period have a variety of deterministic factors (age-at-hire, duration of employment) that distinguish this sub-group of employees from the 'long-term' workforce.<br /><br /><strong>RESULTS: </strong>The 'only 1975-1979' workers had a larger fraction of minorities and female workers. This 'only' sub-group was disproportionately employed in unskilled labor positions. The 'only' workers were younger than the referent group, and a 14-year earlier mean age at death. The all-cause mortality standardized rate ratio [SRR] was 1.58 [95% Cl: 0.97-2.42]. The 'only' group was significantly different from the 'ever' workers with respect to suicides, SRR = 3.74 [95% Cl: 1.86-6.69], and for homicides, SRR = 11.71 [95% Cl: 3.20-30.03].<br /><br /><strong>CONCLUSIONS: </strong>These elevated mortality risks do not seem to be due to PGDP employment exposures to metal dusts or trichloroethylene. Socio-economic factors may be a determinant for the patterns of suicides and murders described for this sub-group of employees. These findings provide guidance for communities with a dominant local employer. Persons who experience short-term hiring may warrant public health services to mitigate their risk of tragic deaths. A case-control study of these deaths is recommended to clarify individual risk behaviors.",
Arsenic,1021687,"Arsenic exposure and motor function among children in Bangladesh Abstract: <strong>BACKGROUND: </strong>Several reports indicate that drinking water arsenic (WAs) and manganese (WMn) are associated with children's intellectual function. Very little is known, however, about possible associations with other neurologic outcomes such as motor function.<br /><br /><strong>METHODS: </strong>We investigated the associations of WAs and WMn with motor function in 304 children in Bangladesh, 8-11 years of age. We measured As and Mn concentrations in drinking water, blood, urine, and toenails. We assessed motor function with the Bruininks-Oseretsky test, version 2, in four subscales-fine manual control (FMC), manual coordination (MC), body coordination (BC), and strength and agility-which can be summarized with a total motor composite score (TMC). REsults: Log-transformed blood As was associated with decreases in TMC [? = -3.63; 95% confidence interval (CI): -6.72, -0.54; p &lt; 0.01], FMC (? = -1.68; 95% CI: -3.19, -0.18; p &lt; 0.05), and BC (? = -1.61; 95% CI: -2.72, -0.51; p &lt; 0.01), with adjustment for sex, school attendance, head circumference, mother's intelligence, plasma ferritin, and blood Mn, lead, and selenium. Other measures of As exposure (WAs, urinary As, and toenail As) also were inversely associated with motor function scores, particularly TMC and BC. Square-transformed blood selenium was positively associated with TMC (? = 3.54; 95% CI: 1.10, 6.0; p &lt; 0.01), FMC (? = 1.55; 95% CI: 0.40, 2.70; p &lt; 0.005), and MC (? = 1.57; 95% CI: 0.60, 2.75; p &lt; 0.005) in the unadjusted models. Mn exposure was not significantly associated with motor function.<br /><br /><strong>CONCLUSION: </strong>Our research demonstrates an adverse association of As exposure and a protective association of Se on motor function in children.",
Arsenic,1026437,"Critical pathway analysis to determine key uncertainties in net impacts on disease burden in Bangladesh of arsenic mitigation involving the substitution of arsenic bearing for groundwater drinking water supplies Abstract: It has been increasingly recognised that calculation of the disease burden due to populations, such as in Bangladesh, extensively using hazardous arsenic bearing well waters, must explicitly account for the trade-off between diarrhoeal disease incidence and that of arsenic-related diseases. This is because it is likely that moves to alternative drinking water sources, be they surface waters or even more distant groundwaters, without further mitigation would result in a concurrent increase in diarrhoeal disease. In this paper, we update the model of Lokuge of the effects of such arsenic mitigation on disease burden in Bangladesh, using updated population data and background disease estimates. We run a critical pathway analysis on the model using Standardised Mortality Ratios (SMRs) for diabetes mellitus and ischemic heart disease from different epidemiological studies recently reviewed by Navas-Acien. Our analysis agrees with that of Lokuge that mitigation simply involving the substitution of a range of surface waters for well water sources with As &gt; 50 microg/L would have a net positive impact on disease burden, as determined by deaths and Disability Life Adjusted Years (DALYs). In contrast, however, there is considerable ambiguity in the analogous results for mitigation for all the population exposed to well water with As &gt; 10 microg/L. Depending upon the data source chosen for diabetes mellitus and ischaemic heart disease SMRs, such mitigation is modelled to have either a positive or a negative net impact on overall disease burden. The modelled negative impacts are entirely commensurate with the rationale for seeking groundwater as an alternative to surface waters as a drinking water supply, and highlight the practical requirement for multiple mitigation strategies, including those directed at ensuring the microbiological safety and continued protection of any alternative water supplies. Our study highlights the need for (i) adequate epidemiological studies involving multiple exposure categories, ideally resulting in an accurate dose-response relationship for arsenic uptake and the non-malignant high incidence conditions diabetes mellitus and ischemic heart disease for individuals with the socioeconomic and nutritional status of the Bangladeshi populations, and (ii) refined estimates of the diarrhoel disease burden arising from usage of surface waters.",
Arsenic,627994,"Genetic events associated with arsenic-induced malignant transformation: Applications of cDNA microarray technology Abstract: Arsenic is a human carcinogen. Our recent work showed that chronic (>18 wk), low-level (125-500 nM) arsenite exposure induces malignant transformation in normal rat liver cell line TRL1215. In these arsenic-transformed cells, thecellular S-adenosylmethionine pool was depleted from arsenic metabolism, resulting in global DNA hypomethylation. DNA methylation status in turn may affect the expression of a variety of genes. This study examined the aberrant gene expression associated with arsenic-induced transformation with the use of Atlas Rat cDNA Expression microarrays. Poly(A(+)) RNA was prepared from arsenic-transformed cells and passage-matched control cells, and (32)P-labeled cDNA probes were synthesized with Clontech Rat cDNA Synthesis primers and moloney murine leukemia virus reverse transcriptase. The hybrid intensity was analyzed with AtlasImage software and normalized with the sum of the four housekeeping genes. Four hybridizations from separate cell preparations were performed, and mean and SEM for the expression of each gene were calculated for statistical analysis. Among the 588 genes, approximately 80 genes ( approximately 13%) were aberrantly expressed. These included genes involved in cell-cycle regulation, signal transduction, stress response, apoptosis, cytokine production and growth-factor and hormone-receptor production and various oncogenes. These initial gene expression analyses for the first time showed potentially important aberrant gene expression patterns associated with arsenic-induced malignant transformation and set the stage for numerous further studies. Mol. Carcinog. 30:79-87, 2001. Published 2001 Wiley-Liss, Inc.",
Arsenic,2279136,"Stress granule formation in Entamoeba histolytica: cross-talk between EhMLBP, EhRLE3 reverse transcriptase and polyubiquitinated proteins Abstract: The Entamoeba histolytica-methylated LINE-binding protein (EhMLBP) binds to methylated repetitive DNA and is a positive regulator of a reverse transcriptase of a long interspersed nucleotide element (LINE). This protein protects trophozoites against heat shock by reducing protein aggregation. The presence of EhMLBP and polyubiquitinated proteins in heat shock-induced protein aggregates raised the question whether these proteins interact. This assumption was confirmed by co-immunoprecipitation experiments: ubiquitinated proteins were detected in the perinuclear region of non-stressed E.?histolytica trophozoites, whereas ubiquitinated proteins were detected in the perinuclear region and colocalized with EhMLBP in cytoplasmic granules in heat-shocked trophozoites. We also observed that overexpression of the reverse transcriptase of EhRLE3 induced the upregulation of EhMLBP expression and the formation of these EhMLBP-containing granules. Since (i) these EhMLBP-containing granules in the cytoplasm of heat-shocked E.?histolytica trophozoites also contain polyubiquitinated proteins and poly(A)(+) mRNA and (ii) their formation is promoted by sodium arsenate, puromycin, and pateamine A and is inhibited by cycloheximide, we propose that these cytoplasmic EhMLBP-containing granules are stress granules. Our data also suggest that the formation of these granules is dependent upon EhMLBP and LINE.",
Arsenic,627900,"Malignant neoplasms among residents of a blackfoot disease-endemic area in Taiwan: High-arsenic artesian well water and cancers Abstract: The objective of this study is to elucidate the association between high-arsenic artesian well water and cancers in endemic area of blackfoot disease, a unique peripheral vascular disease related to continuous arsenic exposure. As compared with the general population in Taiwan, both the standardized mortality ratio (SMR) and cumulative mortality rate were significantly high in blackfoot disease-endemic areas for cancers of bladder, kidney, skin, lung, liver, and colon. The SMRs for cancers of bladder, kidney, skin, lung, liver, and colon were 1100, 772, 534, 320, 170, and 160, respectively, for males, and 2009, 1119, 652, 413, 229, and 168, respectively, for females. A dose-response relationship was observed between SMRs of the cancers and blackfoot disease prevalence rate of the villages and townships in the endemic areas. SMRs of cancers were greater in villages where only artesian wells were used as the drinking water source than in villages using both artesian and shallow wells, and even greater than in villages using shallow wells only.",
Arsenic,1021984,"Simultaneous immobilization of metals and arsenic in acidic polluted soils near a copper smelter in central Chile Abstract: Introduction Acidic and metal(oid)-rich topsoils resulted after 34 years of continuous operations of a copper smelter in the Puchuncaví valley, central Chile. Currently, largescale remediation actions for simultaneous in situ immobilization of metals and As are needed to reduce environmental risks of polluted soils. Aided phytostabilization is a cost-effective alternative, but adequate local available soil amendments have to be identified and management options have to be defined. Materials and methods Efficacy of seashell grit (SG), biosolids (B), natural zeolite (Z), and iron-activated zeolite (AZ), either alone or in mixtures, was evaluated for reducing metal (Cu and Zn) and As solubilization in polluted soils under laboratory conditions. Perennial ryegrass was used to test phytotoxicity of experimental substrates. Results Soil neutralization to a pH of 6.5 with SG, with or without incorporation of AZ, significantly reduces metal (Cu and Zn) solubilization without affecting As solubilization in soil pore water; furthermore, it eliminates phytotoxicity and excessive metal(oid) accumulation in aerial plant tissues. Addition of B or Z to SG-amended soil does not further reduce metal solubilization into soil pore water, but increase As solubilization due to excessive soil neutralization (pH>6.5); however, no significant As increase occurs in aerial plant tissues. Conclusion Simultaneous in situ immobilization of metal(oid) in acidic topsoils is possible through aided phytostabilization.",
Arsenic,1016320,"Development of probabilistic emission inventories of air toxics for Jacksonville, Florida Abstract: Probabilistic emission inventories were developed for 1,3-butadiene, mercury (Hg), arsenic (As), benzene, formaldehyde, and lead for Jacksonville, FL. To quantify inter-unit variability in empirical emission factor data, the Maximum Likelihood Estimation (MLE) method or the Method of Matching Moments was used to fit parametric distributions. For data sets that contain nondetected measurements, a method based upon MLE was used for parameter estimation. To quantify the uncertainty in urban air toxic emission factors, parametric bootstrap simulation and empirical bootstrap simulation were applied to uncensored and censored data, respectively. The probabilistic emission inventories were developed based on the product of the uncertainties in the emission factors and in the activity factors. The uncertainties in the urban air toxics emission inventories range from as small as -25 to +30% for Hg to as large as -83 to +243% for As. The key sources of uncertainty in the emission inventory for each toxic are identified based upon sensitivity analysis. Typically, uncertainty in the inventory of a given pollutant can be attributed primarily to a small number of source categories. Priorities for improving the inventories and for refining the probabilistic analysis are discussed.",
Arsenic,476953,"Levels of arsenic in drinking-water and cutaneous lesions in Inner Mongolia Abstract: The most common health effects from drinking-water containing dissolved arsenic are skin abnormalities and lesions that are typically diagnosed as keratosis and pigment disorder. It was previously reported that the prevalence of cutaneous lesions was about 44% in arsenic-affected villages. However, there has been little research on the relationship between levels of arsenic in drinking-water and cutaneous lesions in Inner Mongolia. One study examined the association between the prevalence of keratosis and levels of arsenic exposure and the relationship between pigment disorder and levels of arsenic exposure among villagers aged 18 years or older in the arsenic-affected village of Hetao Plain in Inner Mongolia, PR China. The study included 227 participants who were affected by cutaneous lesions and 221 participants who were not affected by cutaneous lesions diagnosed in 1996 and 1998. Well-water drunk by the participants was collected to analyze arsenic content. Adjusting for age, sex, and smoking, logistic regression was applied to calculate the risks that arsenic in drinking-water will lead to cutaneous lesions. The results from the logistic regression showed that, with the increase of arsenic concentration in water, the risk of pigment disorder also increased (odds ratio [OR]=5.25, 95% confidence interval [CI] 1.32-83.24 for 50-199 mu g/L; OR=10.97, 95% CI 1.50-79.95 for 200-499 mu g/L; OR=10.00, 95% CI 1.39-71.77 for >= 500 mu g/L (p=0.000), but the association between risk of keratosis and levels of arsenic was not significant (p=0.346). The findings suggest that keratosis is an early feature of arsenic poisoning, and the development of pigment disorder depends on higher doses of arsenic intake rather than keratosis. Further studies are needed to confirm that cutaneous lesions and other adverse health effects occur at low levels of arsenic exposure.",
Arsenic,1579369,"Effects of recharge and discharge on delta2H and delta18O composition and chloride concentration of high arsenic/fluoride groundwater from the Datong Basin, northern China Abstract: To better understand the effects of recharge and discharge on the hydrogeochemistry of high levels of arsenic (As) and fluoride (F) in groundwater, environmental isotopic composition (delta2H and delta18O) and chloride (Cl) concentrations were analyzed in 29 groundwater samples collected from the Datong Basin. High arsenic groundwater samples (As &gt; 50 micog/L) were found to be enriched in lighter isotopic composition that ranged from -92 to -78 per thousand for deuterium (delta2H) and from -12.5 to -9.9 per thousand for oxygen-18 (delta18O). High F-containing groundwater (F &gt; 1 mg/L) was relatively enriched in heavier isotopic composition and varied from -90 to -57 per thousand and from -12.2 to -6.7 per thousand for delta2H and delta18O, respectively. High chloride concentrations and delta18O values were primarily measured in groundwater samples from the northern and southwestern portions of the study area, indicating the effect of evaporation on groundwater. The observation of relatively homogenized and low delta18O values and chloride concentrations in groundwater samples from central part of the Datong Basin might be a result of fast recharge by irrigation returns, which suggests that irrigation using arsenic-contaminated groundwater affected the occurrence of high arsenic-containing groundwater in the basin.",
Arsenic,1677611,"Controlling the Band Gap Energy of Cluster-Assembled Materials Abstract: Cluster-assembled materials combine the nanoscale size and composition-dependentproperties of clusters, which have highly tunable magnetic and electronic properties useful for a great variety of potential technologies. To understand the emergent properties as clusters are assembled into hierarchical materials, we have synthesized 23 cluster-assembled materials composed of As7(3-)-based motifs and different countercations and measured their band gap energies. We found that the band gap energy varies from 1.09 to 2.21 eV. In addition, we have carried out first principles electronic structure studies to identify the physical mechanisms that enable control of the band gap edges of the cluster assemblies. The choice of counterion has a profound effect on the band gap energy in ionic clusterassemblies. The top of the valence band is localized on the arsenic cluster, while the conduction band edge is located on the alkali metal counterions. Changing the counterion changes the position of the conduction band edge, enabling control of the band gap energy. We can also vary the architecture of the ionic solid by incorporating cryptates as counterions, which provide charge but are separated from the clusters by bulky ligands. Higher dimensionality typically decreases the band gap energy through band broadening; however band gap energies increased upon moving from zero-dimensional (0D) to two-dimensional (2D) assemblies. This is because internal electric fields generated by the counterion preferentially stabilize the adjacent lone pair orbitals that mark the top of the valence band. Thus, the choice of the counterion can control the position of the conduction band edge of ionic cluster assemblies. In addition, the dimensionality of the solid via internal electric fields can control the valence band edge. Through covalently linking arsenic clusters into composite building blocks, we have also been able to tune the band gap energy. We used a theoretical description based on cluster orbital theory to provide microscopic understanding of the electronic character of the composite building blocks and the observed variations in the band gap energy. Also, we have shown how dimeric linkers can be used to control the band gap energy. Lastly, we also investigated the effects of charge transfer complexes of M(CO)3 on the band gap energy.",
Arsenic,1268370,"Biological monitoring of environmental pollution and human exposure to metals in Tarragona, Spain. IV. Estimation of the dietary intake Abstract: BIOSIS COPYRIGHT: BIOL ABS. The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) were analyzed in different classes of food items purchased in the area of Tarragona (Catalonia, Spain). A total of 11 food groups were included in the study. Trace element concentrations were measured by ICP-MS. In all food groups, Be, Tl, and V were under the respective detection limits. The dietary intake of the remaining 8 elements was determined by a total diet-study. Calculations were made based on previous data on the consumption of the selected food items in the area. Total daily intakes (mug) were the following: As 272.7, Cd 18.2, Cr 139.2, Hg 4.8, Mn 2190, Ni 143.8, Pb 48.6, and Sn 63.7. These values are in the same order as most data for dietary intakes found in recent surveys from different countries. Moreover, the dietary daily intake of the toxic elements As, Cd, Hg, and Pb should no",
Arsenic,2149163,"Identification and characterization of metabolic properties of bacterial populations recovered from arsenic contaminated ground water of North East India (Assam) Abstract: Diversity of culturable bacterial populations within the Arsenic (As) contaminated groundwater of North Eastern state (Assam) of India is studied. From nine As contaminated samples 89 bacterial strains are isolated. 16S rRNA gene sequence analysis reveals predominance of Brevundimonas (35%) and Acidovorax (23%) along with Acinetobacter (10%), Pseudomonas (9%) and relatively less abundant (&lt;5%) Undibacterium, Herbaspirillum, Rhodococcus, Staphylococcus, Bosea, Bacillus, Ralstonia, Caulobacter and Rhizobiales members. High As(III) resistance (MTC 10-50 mM) is observed for the isolates obtained from As(III) enrichment, particularly for 3 isolates of genus Brevundimonas (MTC 50 mM). In contrast, high resistance to As(V) (MTC as high as 550 mM) is present as a ubiquitous property, irrespective of isolates' enrichment condition. Bacterial genera affiliated to other groups showed relatively lower degree of As resistance [MTCs of 15-20 mM As(III) and 250-350 mM As(V)]. As(V) reductase activity is detected in strains with high As(V) as well as As(III) resistance. A strong correlation could be established among isolates capable of reductase activity and siderophore production as well as As(III) tolerance. A large number of isolates (nearly 50%) is capable of anaerobic respiration using alternate inorganic electron acceptors [As(V), Se(VI), Fe(III), [Formula: see text] , [Formula: see text] , [Formula: see text] ]. Ability to utilize different carbon sources ranging from C2-C6 compounds along with some complex sugars is also observed. Particularly, a number of strains is found to possess ability to grow chemolithotrophically using As(III) as the electron donor. The study reports for the first time the identity and metabolic abilities of bacteria in As contaminated ground water of North East India, useful to elucidate the microbial role in influencing mobilization of As in the region.",
Arsenic,1508627,"Gastrointestinal tuberculosis is not associated with proton pump inhibitors: A retrospective cohort study Abstract: <strong>AIM: </strong>To evaluate the effect of proton pump inhibitors (PPIs) on the development of gastrointestinal tuberculosis.<br /><br /><strong>METHODS: </strong>All patients who were more than 20 years old and who had received a prescription for PPIs among those who visited Seoul National University Hospital from January 1, 2005 to December 31, 2009 were identified. Due to the low sensitivity of the microbiologic test and the nonspecific pathologic findings, the diagnosis of gastrointestinal tuberculosis was confirmed through the presence of active ulcerations and the responses to anti-tuberculosis medications. The patients were divided into two groups according to treatment duration (group 1: ? 3 mo; group 2: &gt; 3 mo) and were followed up from the time they took the first prescription of PPIs until their last visit. Logistic regression analysis was used to calculate the relative risks (RR) and 95%CI, adjusting for covariates.<br /><br /><strong>RESULTS: </strong>Among the 61??834 patients exposed to PPIs (50??534 in group 1; 11??300 in group 2), 21 patients were diagnosed with PPI-associated gastrointestinal tuberculosis during 124??274 person-years of follow-up. Of 21 patients, the 12 who revealed only scar changes in the colonoscopy were excluded from the statistical analyses. Of those who remained, 2 were excluded because they underwent gastrointestinal endoscopy within 4 wk of the first prescription for PPIs. Longer exposure to PPI was associated with a higher mean age (55.0 ± 14.5 in group 1 vs 58.2 ± 13.3 in group 2, P &lt; 0.001) and a higher Charlson co-morbidity index (0.50 ± 0.93 in group 1 vs 0.77 ± 1.14 in group 2, P &lt; 0.001). The true incidence of active gastrointestinal tuberculosis was 0.65 per 1000 person-years in group 1 and 0.03 per 1 000 person-years in group 2. Like the less-than-three-month PPI treatment period in group 1, the over-three-month PPI therapy period in group 2 was not associated with increased risk of acquiring gastrointestinal tuberculosis, after adjusting for age and co-morbidities, whereas the Charlson co-morbidity index was associated with increased risk of acquiring gastrointestinal tuberculosis based on the score [RR: (reference 1) in group 1 vs 1.518 in group 2; 95% CI: 1.040-2.216, P = 0.03].<br /><br /><strong>CONCLUSION: </strong>Long-term PPI therapy does not seem to be associated with increased risk of acquiring gastrointestinal tuberculosis, but a higher Charlson co-morbidity index is associated with such.",
Arsenic,1677552,"Can Arsenates Replace Phosphates in Natural Biochemical Processes? A Computational Study Abstract: A bacterial strain, GFAJ-1 was recently proposed to be substituting arsenic for phosphorus to sustain its growth. We have performed theoretical calculations for analyzing this controversial hypothesis by examining the addition of phosphate to ribose and glucose. Dispersion corrected Density Functional Theory (DFT) calculations in small molecules and QM/MM calculations on clusters derived from crystal structure are performed on structures involved in phosphorylation, considering both phosphates and arsenates. The exothermicity as well as the activation barriers for phosphate and arsenate transfer were examined. Quantum mechanical studies reveal that the relative stability of the products decrease marginally with successive substitution of P with As. However, simultaneously, the transition state barriers decrease with P replacement. This indicates that kinetically, addition of As is more facile. Pseudorotation barriers for the pentavalent intermediates formed during the nucleophilic attack are also analyzed. A monotonic increase in barriers is observed for pseudorotation with the successive replacement of phosphorus with arsenic in methyl-DHP A glucokinase crystal structure was chosen to construct a model system for QM/MM calculations. Free energy of the reaction (?G) reduces by less than 2.0 kcal/mol and the activation barrier (?G‡) decreases by ~ 1 kcal/mol on arsenic incorporation. Thus, both DFT and QM/MM calculations show that arsenic can readily substitute phosphorus in key biomolecules. Secondary kinetic isotope effects for phosphorylation mechanism obtained by QM/MM calculations are also reported. The solvent kinetic isotopic effect (SKIE) for ATP and ATP (As) are calculated to be 5.81 and 4.73, respectively. A difference of ~ 1.0 in SKIE suggests that it should be possible to experimentally determine the As - phosphorylation process.",
Arsenic,1248887,"Nitrate and trace elements in municipal and bottled water in Spain Abstract: OBJECTIVES: To describe levels of nitrate and trace elements in drinking water from the study areas of a multicase-control study of cancer in Spain (MCC-Spain). METHODS: A total of 227 tap water samples were randomly collected from 67 municipalities in 11 provinces and the nine most frequently consumed bottled water brands were sampled to measure levels of nitrate, arsenic, nickel, chromium, cadmium, lead, selenium and zinc. RESULTS: The median nitrate level was 4.2mg/l (range&lt;1-29.0), with similar levels in rural and urban municipalities (p=0.86). Trace elements were unquantifiable in 94% of tap water samples. Differences between areas were significant for nitrate (p&lt;0.001) and arsenic (p=0.03). Only nitrate was quantifiable in bottled water (range 2.3-15.6mg/l). CONCLUSIONS: Nitrate levels in municipal water differed between regions and were below the regulatory limit in all samples, including bottled water. Trace element levels were low and mainly unquantifiable in tap and bottled water.",
Arsenic,1022073,"Changes in serum thioredoxin among individuals chronically exposed to arsenic in drinking water Abstract: It is well known that oxidative damage plays a key role in the development of chronic arsenicosis. There is a complex set of mechanisms of redox cycling in vivo to protect cells from the damage. In this study, we examined the differences in the levels of serum thioredoxin1 (TRX1) among individuals exposed to different levels of arsenic in drinking water and detected early biomarkers of arsenic poisoning before the appearance of skin lesions. A total of 157 subjects from endemic regions of China were selected and divided into arsenicosis group with skin lesions (total intake of arsenic: 8.68-45.71mg-year) and non-arsenicosis group without skin lesions, which further divided into low (0.00-1.06mg-year), medium (1.37-3.55mg-year), and high (4.26-48.13mg-year) arsenic exposure groups. Concentrations of serum TRX1 were analyzed by an ELISA method. Levels of water arsenic and urinary speciated arsenics, including inorganic arsenic (iAs), monomethylated arsenic (MMA), and dimethylated arsenic (DMA), were determined by hydride generation atomic absorption spectrometry. Our results showed that the levels of serum TRX1 in arsenicosis patients were significantly higher than that of the subjects who were chronically exposed to arsenic, but without skin lesions. A positive correlation was seen between the levels of serum TRX1 and the total water arsenic intake or the levels of urinary arsenic species. The results of this study indicate that arsenic exposure could significantly change the levels of human serum TRX1, which can be detected before arsenic-specific dermatological symptoms occur. This study provides further evidence on revealing the mechanism of arsenic toxicity.",
Arsenic,1677398,"Minimization of the contact resistance between InAs nanowires and metallic contacts Abstract: We investigate different processes for optimizing the formation of Ohmic contacts to InAs nanowires. The nanowires are grown via molecular beam epitaxy without the use of metal catalysts. Metallic contacts are attached to the nanowires by using an electron beam lithography process. Before deposition of the contacts, the InAs nanowires are treated either by wet etching in an ammonium polysulfide (NH(4))(2)S(x) solution or by an argon milling process in order to remove a surface oxide layer. Two-point electrical measurements show that the resistance of the ammonium polysulfide-treated nanowires is two orders of magnitude lower than that of the untreated nanowires. The nanowires that are treated by the argon milling process show a resistance which is more than an order of magnitude lower than that of those treated with ammonium polysulfide. Four-point measurements allow us to extract an upper bound of 1.4 × 10(-7) ? cm(2) for the contact resistivity of metallic contacts on nanowires treated by the argon milling process.",
Arsenic,2298674,"Maternal-child transfer of essential and toxic elements through breast milk in a mine-waste polluted area Abstract: Objective: To determine the daily intake of essential micronutrients and toxic elements through breast milk in exclusive and nonexclusive breastfed infants living in an area with major mine tailing deposition (n?=?24), compared with a control area (n?=?11). Study Design: The milk volume ingested by 2 to 4 and 4 to 6?month infants was measured by a stable isotopic method. Elements in milk, maternal and infant urine, and drinking water were measured by inductively coupled plasma mass spectrometry (ICP-MS). Results: Similar breast milk volume and essential micronutrients intake in groups of exclusively breastfed infants, but more cadmium, boron, and lithium through breastfeeding in experimental area was found. This exposure was even higher in the nonexclusively breastfed infants, who also ingested more arsenic, boron, and lithium than exclusive breastfed infants. Conclusion: The use of the deuterium and the ICP-MS methods made it possible to evaluate the exact amount of essential and toxic elements ingested by infants through breast milk demonstrating that lower amount of toxic elements are transferred to exclusive breastfed infants compared with those who additionally received nonmaternal milk.",
Arsenic,1355638,Assessment of Arsenic and Selenium Concentration with Chlorophyll Contents of Sugar Beet (Beta vulgaris var.saccharifera) and Wheat (Triticum aestivum) Exposed to Municipal Sewage Sludge Doses Abstract: ,
Arsenic,1579247,"Rhizosphere colonization and arsenic translocation in sunflower (Helianthus annuus L.) by arsenate reducing Alcaligenes sp. strain Dhal-L Abstract: In the present study, six arsenic-resistant strains previously isolated were tested for their plant growth promoting characteristics and heavy metal resistance, in order to choose one model strain as an inoculum for sunflower plants in pot experiments. The aim was to investigate the effect of arsenic-resistant strain on sunflower growth and on arsenic uptake from arsenic contaminated soil. Based on plant growth promoting characteristics and heavy metal resistance, Alcaligenes sp. strain Dhal-L was chosen as an inoculum. Beside the ability to reduce arsenate to arsenite via an Ars operon, the strain exhibited 1-amino-cyclopropane-1-carboxylic acid deaminase activity and it was also able to produce siderophore and indole acetic acid. Pot experiments were conducted with an agricultural soil contaminated with arsenic (214 mg kg(-1)). A real time PCR method was set up based on the quantification of ACR3(2) type of arsenite efflux pump carried by Alcaligenes sp. strain Dhal-L, in order to monitor presence and colonisation of the strain in the bulk and rhizospheric soil. As a result of strain inoculation, arsenic uptake by plants was increased by 53 %, whereas ACR3(2) gene copy number in rhizospheric soil was 100 times higher in inoculated than in control pots, indicating the colonisation of strain. The results indicated that the presence of arsenate reducing strains in the rhizosphere of sunflower influences arsenic mobilization and promotes arsenic uptake by plant.",
Arsenic,628795,"Protective effect of methionine supplementation on arsenic-induced alteration of glucose homeostasis Abstract: Short term exposure of arsenic produces carbohydrate depletion and hypoglycemia. Dietary deficiency of methionine causes impaired biotransformation of arsenic which has been attributed to the pathogenesis of different diseases induced by arsenic. Accordingly, the effects of methionine supplementation on the altered glucose homeostasis induced by arsenic were studied. Arsenic (as sodium arsenite) treatment (i.p) of male Wistar rats (weighing 80-100 g) at a dose of 5.55 mg kg(-1) body weight (equivalent to 35% LD50) per day for a period of 21 days caused a significant diminution in blood glucose level and fall in liver glycogen and pyruvic acid contents. The free amino acid nitrogen content of liver was elevated while that of kidney was decreased after arsenic treatment. Transaminase activities in liver and kidney were not significantly altered except that glutamate-pyruvate transaminase activity of kidney decreased significantly after arsenic treatment. Methionine supplementation reversed the above changes except decreased liver glycogen due to arsenic treatment. It may be suggested that hypoglycemia with associated decreased glycolytic activity induced by arsenic treatment at the present dose and duration can be partially counteracted by dietary methionine supplementation.",
Arsenic,1579310,"Arsenic inhibits autophagic flux activating the Nrf2-Keap1 pathway in a p62-dependent manner Abstract: The Nrf2-Keap1 signaling pathway is a protective mechanism promoting cell survival. Activation of the Nrf2 pathway by natural compounds has been proven to be an effective strategy for chemoprevention. Interestingly, a cancer-promoting function of Nrf2 has been recently observed in many types of tumors due to deregulation of the Nrf2-Keap1 axis, which leads to constitutive activation of Nrf2. Here, we report a novel mechanism of Nrf2 activation by arsenic that is distinct from that of chemopreventive compounds. Arsenic deregulates the autophagic pathway through blockage of autophagic flux, resulting in accumulation of autophagosomes and sequestration of p62, Keap1, and LC3. Thus, arsenic activates Nrf2 through a non-canonical mechanism (p62-dependent), leading to a chronic, sustained activation of Nrf2. In contrast, activation of Nrf2 by sulforaphane and tert-butylhydroquinone depend upon Keap1-C151 and not p62 (the canonical mechanism). More importantly, SF and tBHQ do not have any effect on autophagy. In fact, SF and tBHQ alleviate arsenic-mediated deregulation of autophagy. Collectively, these findings provide evidence that arsenic causes prolonged activation of Nrf2 through autophagy dysfunction, possibly providing a similar scenario to constitutive activation of Nrf2 found in certain human cancers. This may represent a previously unrecognized mechanism underlying arsenic toxicity and carcinogenicity in humans.",
Arsenic,1346783,"Assessment of heavy metal pollution in lake sediments of Katedan Industrial Development Area, Hyderabad, India Abstract: Spatial distribution and temporal trends studies were carried out at Katedan Industrial Development Area (KIDA) near Hyderabad, capital of Andhra Pradesh state, India under Indo-Norwegian Institutional Cooperation Program, to find out the extent of contamination in streams and lake sediments from the discharge of industrial effluents. Stream and lake sediment samples were collected from the five lakes in the study area and connecting water streams. The samples were analyzed by XRF spectrometer for toxic elements. The studies reveal that the stream sediments with in the KIDA and the impounded Noor Mohammed Lake down stream have high concentration of some of the toxic elements like chromium, nickel, lead, arsenic, zinc etc. The geology of the area indicates that the study area consists of residual soil of acidic rocks, which are predominantly of Archaean gneisses and granites having low to medium concentrations of chromium and nickel. The source of these high concentration of elements like lead 2,300 mg/kg, copper 1,500 mg/kg, arsenic 500 mg/kg, chromium 500 mg/kg etc. cannot be derived from the surrounding acidic rocks and may be attributed to the industrial effluents released in the ditches and random dumping of hazardous solid waste. It was observed that the metal concentrations increased in the streams during the dry season (pre-monsoon period). After the monsoon rains, the metal concentrations in the streams were reduced by half which may be due to dilution. The eroded sediments are deposited in the lake where very high concentrations were encountered. Overflowing of the lake will spread the contamination further downstream. The lake sediments will remain as a major source of contamination by desorption to the water phase regardless of what happens to the effluent discharge in the KIDA. However, some samples showed enrichment of lead, arsenic and nickel during post-monsoon, which were collected near the dumpsite due to the leaching of toxic elements from the dump site to the lakes. Some of the toxic elements like nickel and copper have not shown any dilution but have increased after the rains, which could be due to the leaching of arsenic from the dumpsite to the lake along with rainwater. Geochemical maps showing the distribution of heavy/trace elements in streams and lakes are prepared and presented in this paper. Effect of toxic elements on the health of the residents in the surrounding residential areas is also discussed.",
Arsenic,627315,"Mechanism of comutagenesis of sodium arsenite with n-methyl-n-nitrosourea Abstract: Arsenic compounds are known carcinogens. Although many carcinogens are also mutagens, we have previously shown that sodium arsenite is not mutagenic at either the Na+/K+ ATPase orhprt locus in Chinese hamster V79 cells. It can, however, enhance UV-mutagenesis. We now confirm the nonmutagenicity of sodium arsenite in line G12, a pSV2gpt-transformed V79 (hprt ?) cell line, which is able to detect multilocus deletions in addition to point mutations and small deletions. The lack of arsenic mutagenicity has led to studies emphasizing its comutagenicity. Sodium arsenite at relatively nontoxic concentrations (5 ?M for 24 h or 10 ?M for 3 h) is comutagenic withN-methyl-N-nitrosourea (MMU) at thehprt locus in V79 cells. Using a nick translation assay, which measures DNA strand breaks by incorporating radioactive deoxyribonucleoside monophosphate at their 3?OH ends in permeabilized cells, we found that much more incorporation was seen in cells treated with MNU (4 mM, 15 min) followed by 3-h incubation with 10 ?M sodium arsenite compared with cells exposed to the same MNU treatment followed by 3-h incubation without sodium arsenite. This result shows that in the presence of arsenite, strand breaks resulting from MNU or its repair accumulate over a 3-h period. We suggest that the repair of MNU-induced DNA lesions may be inhibited by arsenite either by affecting the incorporation of dNMPs into the MNU-damaged DNA template or by interfering with the ligation step.",
Arsenic,1234412,"Malsegregation as a possible mechanism of aneuploidy induction by metal salts in MRC-5 human cells Abstract: Many aneugenic compounds are known to affect one or more components of the mitotic apparatus leading to an erroneous migration of chromosomes. Malsegregation occurs when a chromosome (or a chromatid) fails to migrate and remains at the metaphase plate. Nondisjunction implies the lack of dissociation between sister chromatids and the migration of both together to the same pole. The aim of the present study was to provide evidence that the aneugenic effect of some metal salts is the consequence of malsegregation at anaphase and that it is not caused by nondisjunction mechanisms. The frequencies of lagging chromosomes at anaphase-telophase of mitosis, hypoploid metaphases, and kinetochore-positive micronuclei induced by cadmium chloride, potassium dichromate, and cacodilic acid (dimethylarsinic acid) in MRC-5 human cells were compared. The data indicate that all the tested compounds are able to induce aneuploidy in MRC-5 human cells. Positive, statistically significant correlations were found when kinetochore-positive micronuclei, hypoploidy, and lagging chromosome frequencies were compared. The results suggest that malsegregation is the main mechanism involved in the induction of aneuploidy by metal salts in MRC-5 cells.",
Arsenic,627114,"Lung cancer and arsenic concentrations in drinking water in Chile Abstract: Cities in northern Chile had arsenic concentrations of 860 microg/liter in drinking water in the period 1958-1970. Concentrations have since been reduced to 40 microg/liter. We investigated the relation between lung cancer and arsenic in drinking water in northern Chile in a case-control study involving patients diagnosed with lung cancer between 1994 and 1996 and frequency-matched hospital controls. The study identified 152 lung cancer cases and 419 controls. Participants were interviewed regarding drinking water sources, cigarette smoking, and other variables. Logistic regression analysis revealed a clear trend in lung cancer odds ratios and 95% confidence intervals (CIs) with increasing concentration of arsenic in drinking water, as follows: 1, 1.6 (95% CI = 0.5-5.3), 3.9 (95% CI = 1.2-12.3), 5.2 (95% CI = 2.3-11.7), and 8.9 (95% CI = 4.0-19.6), for arsenic concentrations ranging from less than 10 microg/liter to a 65-year average concentration of 200-400 microg/liter. There was evidence of synergy between cigarette smoking and ingestion of arsenic in drinking water; the odds ratio for lung cancer was 32.0 (95% CI = 7.2-198.0) among smokers exposed to more than 200 microg/liter of arsenic in drinking water (lifetime average) compared with nonsmokers exposed to less than 50 microg/liter. This study provides strong evidence that ingestion of inorganic arsenic is associated with human lung cancer.",
Arsenic,1026117,"Rural communities' preferences for arsenic mitigation options in Bangladesh Abstract: In the context of arsenic contamination of groundwater in Bangladesh, this paper analyses rural people's preferences for arsenic-free drinking water options. A particular focus is on rural households' willingness to pay for piped water supply which can provide a sustainable solution to the arsenic problem, and how the preference for piped water supply compares with that for various other household/community-based arsenic mitigation technologies. The analysis is based on data collected in a survey of over 2700 households in rural Bangladesh. Six arsenic mitigation technologies were selected for the study: three-kolshi (pitcher) method, activated alumina method (household-based and community-based), dugwell, pond sand filter and deep tubewell (handpump). The survey results indicate that, after taking into consideration the initial and recurring costs, convenience, associated risks and the advantages and disadvantages of each selected technology, the preference of the rural people is overwhelmingly in favor of deep tubewells, followed by the three-kolshi method. The analysis reveals a strong demand for piped water in both arsenic-affected and arsenic-free rural areas, and scope of adequate cost recovery. Between piped water and other arsenic mitigation technologies, the preference of the rural people is found to be predominantly in favor of the former.",
Arsenic,2149108,"Oxidative stress-inducible truncated serine/arginine-rich splicing factor 3 regulates interleukin-8 production in human colon cancer cells Abstract: Serine/arginine-rich splicing factor 3 (SRSF3) is a member of the SR protein family and plays wide-ranging roles in gene expression. The human SRSF3 gene generates two alternative splice transcripts, a major mRNA isoform (SRSF3-FL) encoding functional full-length protein and a premature termination codon (PTC)-containing isoform (SRSF3-PTC). The latter is degraded through nonsense-mediated mRNA decay (NMD). Treatment of a human colon cancer cell line (HCT116) with 100 ?M sodium arsenite increased SRSF3-PTC mRNA levels without changing SRSF3-FL mRNA levels. A chemiluminescence-based NMD reporter assay system demonstrated that arsenite treatment inhibited NMD activity and increased SRSF3-PTC mRNA levels in the cytoplasm, facilitating translation of a truncated SRSF3 protein (SRSF3-TR) from SRSF3-PTC mRNA. SRSF3-TR lacked two-thirds of Arg/Ser-rich (RS) domain whose phosphorylation state is known to be crucial for subcellular distribution. SRSF3-FL was localized in the nucleus, while overexpressed SRSF3-TR was diffusely distributed in the cytoplasm and the nucleus. A part of SRSF3-TR was also associated with stress granules in the cytoplasm. Interestingly, treatment of HCT116 cells with a small interference RNA specifically targeting SRSF3-PTC mRNA significantly attenuated arsenite-stimulated induction of c-JUN protein, its binding activity to the AP-1 binding site (-126 to 120 bp) in the interleukin (IL)-8 gene promoter, and AP-1 promoter activity, resulting in significant reduction of arsenite-stimulated IL-8 production. Our results suggest that SRSF3-TR may function as a positive regulator of oxidative stress-initiated inflammatory responses in colon cancer cells.",
Arsenic,2343438,"The influence of metamorphic grade on arsenic in metasedimentary bedrock aquifers: A case study from Western New England, USA Abstract: Elevated As occurs in many meta-sedimentary bedrock aquifers where elevated bulk-rock As content is one of the primary controls on the concentration of As in groundwater. This study was designed to determine As concentrations in a black shale, black slate and black phyllite sequence that comprises the bedrock aquifer system of the Taconic Mountain region of southwestern Vermont and adjacent New York State. Variability in groundwater As concentrations provides the impetus for this study: 25% of wells in weakly metamorphosed shales and slates (&lt;lower chlorite zone) exceed 10?g/L (133nmol/L) As, yet only 3% of wells in stratigraphically-equivalent phyllites (metamorphosed to ?upper chlorite zone) exceed 10?g/L As. Geochemical analysis indicates that whole-rock As content is inversely proportional to metamorphic grade, ranging from a mean of 26.9mgkg(-1) in low-grade black shales and slates to 13.8mgkg(-1) in higher-grade black phyllites. The differences in As concentrations are statistically significant (p&lt;0.03), and Cu, Ni, Pb and Zn are also significantly (p&lt;0.03) depleted in higher-grade phyllites. These differences are attributed to recrystallization of pyrite with increasing metamorphic grade, a process which introduces As and other trace elements into pore fluids, after which the high mobility of As makes it susceptible to be leached out of metapelites. Data from this study and previous research indicates that depletion of As from metapelites tends to occur once the rocks reach upper chlorite zone or lower biotite zone, corresponding to metamorphic temperatures of ~250-350°C. This suggests that, in the absence of subsequent hydrothermal mineralization (e.g. arsenopyrite in late-stage veins), metapelites metamorphosed to upper chlorite zone or higher will be less likely to foster elevated As in groundwater compared to their lower-grade shale and slate counterparts.",
Arsenic,711002,"Oxidative stress and hepatic stellate cell activation are key events in arsenic induced liver fibrosis in mice Abstract: Arsenic is an environmental toxicant and carcinogen. Exposure to arsenic is associated with development of liver fibrosis and portal hypertension through ill defined mechanisms. We evaluated hepatic fibrogenesis after long term arsenic exposure in a murine model. BALB/c mice were exposed to arsenic by daily gavages of 6 ?g/gm body weight for 1 year and were evaluated for markers of hepatic oxidative stress and fibrosis, as well as pro-inflammatory, pro-apoptotic and pro-fibrogenic factors at 9 and 12 months. Hepatic NADPH oxidase activity progressively increased in arsenic exposure with concomitant development of hepatic oxidative stress. Hepatic steatosis with occasional collection of mononuclear inflammatory cells and mild portal fibrosis were the predominant liver lesion observed after 9 months of arsenic exposure, while at 12 months, the changes included mild hepatic steatosis, inflammation, necrosis and significant fibrosis in periportal areas. The pathologic changes in the liver were associated with markers of hepatic stellate cells (HSCs) activation, matrix reorganization and fibrosis including ?-smooth muscle actin, transforming growth factor-?1, PDGF-R?, pro-inflammatory cytokines and enhanced expression of tissue inhibitor of metalloproteinase-1 and pro(?) collagen type I. Moreover, pro-apoptotic protein Bax was dominantly expressed and Bcl-2 was down-regulated along with increased number of TUNEL positive hepatocytes in liver of arsenic exposed mice. Furthermore, HSCs activation due to increased hepatic oxidative stress observed after in vivo arsenic exposure was recapitulated in co-culture model of isolated HSCs and hepatocytes exposed to arsenic. These findings have implications not only for the understanding of the pathology of arsenic related liver fibrosis but also for the design of preventive strategies in chronic arsenicosis.",
Arsenic,1023951,"Can administration of potentized homeopathic remedy, Arsenicum album, alter antinuclear antibody (ANA) titer in people living in high-risk arsenic contaminated areas? I. A correlation with certain hematological parameters Abstract: To examine whether elevated antinuclear antibody (ANA) titers reported in random human population of arsenic contaminated villages can be reverted to the normal range by administration of a potentized homeopathic drug, Arsenicum album, randomly selected volunteers in two arsenic contaminated villages and one arsenic-free village in West Bengal (India) were periodically tested for their ANA titer as well as various blood parameters in two types of experiments: 'placebo-controlled double blind' experiment for shorter duration and 'uncontrolled verum fed experiment' for longer duration. Positive modulation of ANA titer was observed along with changes in certain relevant hematological parameters, namely total count of red blood cells and white blood cells, packed cell volume, hemoglobin content, erythrocyte sedimentation rate and blood sugar level, mostly within 2 months of drug administration. Thus, Arsenicum album appears to have great potential for ameliorating arsenic induced elevated ANA titer and other hematological toxicities.",
Arsenic,1031305,"Survival following massive arsenic ingestion Abstract: A case of a 30-year-old man who ingested a massive quantity of arsenic (approximately 2,150 mg) in an apparent suicide attempt is presented. Aggressive initial therapy, including fluid resuscitation, chelation therapy, and hemodialysis, resulted in the patient's survival. The successful management of arsenic intoxication requires both prompt recognition and the initiation of specific and aggressive therapeutic modalities.",
Arsenic,1519015,"Facile dimethylarsenic exchange and pyramidal inversion in its cysteine and glutathione adducts Abstract: Rapid thiolate exchange of dimethylarsonium, Me2As(+), is observed between two different thiolate species in solution. NMR is used to characterize the equilibrium constants for interthiol transfer as well the rapid intra molecular conformational dynamics which leads to the coalescence of diastereotopic methyl resonances. These rapid exchange kinetics have important consequences of arsenic's toxicity and pharmacology.",
Arsenic,1337511,"Mobilization of arsenic in aquifers from the Datong Basin, China: Evidence from geochemical and iron isotopic data Abstract: Iron isotope compositions of various Fe pools in aquifer sediments were measured at a known As-contaminated site in the Datong Basin, China. The ?(56)Fe values of HCl-extracted poor-crystalline Fe(III) range widely from -0.41‰ to 0.36‰. We interpret the low Fe(II)/Fe(Extractable) ratios (&lt;50%) and the negative correlation between Fe(II)/Fe(Extractable) and ?(56)Fe values in HCl-extracted poor-crystalline Fe to be best explained by redox cycling of Fe induced by microbial Fe(III) reduction. However, the high Fe(II)/Fe(Extractable) ratios (?70%) and positive correlation between Fe(II)/Fe(Extractable) and ?(56)Fe values for HCl-extracted poor-crystalline Fe indicates production of sulfides (FeSs). The ?(56)Fe values of crystalline Fe(III) extracted by reductant appears to be comparatively small varying from -0.01‰ to 0.24‰, which is consistent with the ?(56)Fe values for ferric oxides/hydroxides having undergone microbial Fe(III) reduction. The Fe isotope composition of various Fe pools shows the transformation between crystalline Fe(III) and poor-crystalline crystalline Fe(III) and the secondary Fe(II) phases has already occurred or is occurring in aquifer sediments. More importantly, there is a significant difference in the As concentrations in crystalline Fe(III) oxides/hydroxides and HCl-extracted Fe phases. The concentrations of As range from 1.6 to 29.9mgkg(-1) and from 0.6 to 3.0mgkg(-1), for crystalline Fe(III) and HCl-extracted Fe phases respectively. Accordingly, the transformation of Fe minerals induced by microbial Fe(III) reduction can contribute to the mobilization of As. This study is the first to examine the Fe isotope compositions in high As aquifer sediments; the results show that the Fe isotope would be an important tool in demonstrating the enrichment of As in groundwater.",
Arsenic,1029307,"Chronic exposure to low concentration of arsenic is immunotoxic to fish: Role of head kidney macrophages as biomarkers of arsenic toxicity to Clarias batrachus Abstract: The present study was aimed at elucidating the effect of chronic low-level arsenic exposure on the head kidney (HK) of Clarias batrachus and at determining the changes in head kidney macrophage (HKM) activity in response to arsenic exposure. Chronic exposure (30 days) to arsenic (As(2)O(3), 0.50 microM) led to significant increase in arsenic content in the HK accompanied by reduction in both HKM number and head kidney somatic index (HKSI). Arsenic induced HK hypertrophy, reduction in melano-macrophage population and increased hemosiderin accumulation. Transmission electron microscopy of 30 days exposed HKM revealed prominent endoplasmic reticulum, chromatin condensation and loss in structural integrity of nuclear membrane. Head kidney macrophages from exposed fish demonstrated significant levels of superoxide anions but on infection with Aeromonas hydrophila were unable to clear the intracellular bacteria and died. Exposure-challenge experiments with A. hydrophila revealed that chronic exposure to micromolar concentration of arsenic interfered with the phagocytic potential of HKM, helped in intracellular survival of the ingested bacteria inside the HKM inducing significant HKM cytotoxicity. The immunosuppressive effect of arsenic was further evident from the ability of A. hydrophila to colonize and disseminate efficiently in exposed fish. Enzyme linked immunosorbent assay indicated that chronic exposure to arsenic suppressed the production of pro-inflammatory 'IL-1beta like' factors from HKM. It is concluded that arsenic even at very low concentration is immunotoxic to fish and the changes observed in HKM may provide a useful early biomarker of low-level xenobiotic exposure.",
Arsenic,1597331,"Bioanalytical separation and preconcentration using ionic liquids Abstract: Ionic liquids (ILs) are novel solvents that display a number of unique properties, such as negligible vapor pressure, thermal stability (even at high temperatures), favorable viscosity, and miscibility with water and organic solvents. These properties make them attractive alternatives to environmentally unfriendly solvents that produce volatile organic compounds. In this article, a critical review of state-of-the-art developments in the use of ILs for the separation and preconcentration of bioanalytes in biological samples is presented. Special attention is paid to the determination of various organic and inorganic analytes-including contaminants (e.g., pesticides, nicotine, opioids, gold, arsenic, lead, etc.) and functional biomolecules (e.g., testosterone, vitamin B12, hemoglobin)-in urine, blood, saliva, hair, and nail samples. A brief introduction to modern microextraction techniques based on ILs, such as dispersive liquid-liquid microextraction (DLLME) and single-drop microextraction (SDME), is provided. A comparison of IL-based methods in terms of their limits of detection and environmental compatibilities is also made. Finally, critical issues and challenges that have arisen from the use of ILs in separation and preconcentration techniques are also discussed.",
Arsenic,1016435,"Dietary intake of arsenic by children and adults from Jinhu area of China Abstract: The aim of this study was to estimate the dietary intake of arsenic (As) by children and adults from Jinhu area of China. A duplicate diet approach was used to collect diet samples in November and December 2007. The As content was measured by hydride generation atomic fluorescence spectrometry. The As intakes (median) for different group were: children: 0.6 microg kg(-1) bw day(-1) or 6.7 microg kg(-1) bw week(-1); adults: 0.5 microg kg (-1) bw day(-1) or 3.8 microg kg (-1) bw week(-1), none of which exceeded the provisional tolerable weekly intake (PTWI) of 15 microg kg (-1) bw week(-1) for As proposed by the World Health Organization (WHO). The median and maximum of the children group amounted to 44.7% and 125.3% of the PTWI; the values for adults were 25.3% and 118.7%, respectively. There were 3.3% of children whose weekly As intake exceeded the PTWI, and there were 6.7% of adults whose weekly As intake exceeded the PTWI. It is concluded that dietary As intake was safe for most people in Jinhu area, but the high dietary As intake for a minority of people in this area deserves attention.",
Arsenic,1326786,"Distinct Nrf1/2-independent mechanisms mediate As 3+-induced glutamate-cysteine ligase subunit gene expression in murine hepatocytes Abstract: Trivalent arsenite (As(3+)) is a known human carcinogen that is also capable of inducing apoptotic cell death. Increased production of reactive oxygen species is thought to contribute to both the carcinogenic and the cytotoxic effects of As(3+). Glutathione (GSH) constitutes a vital cellular defense mechanism against oxidative stress. The rate-limiting enzyme in GSH biosynthesis is glutamate-cysteine ligase (GCL), a heterodimeric holoenzyme composed of a catalytic (GCLC) and a modifier (GCLM) subunit. In this study, we demonstrate that As(3+) coordinately upregulates Gclc and Gclm mRNA levels in a murine hepatocyte cell line resulting in increased GCL subunit protein expression, holoenzyme formation, and activity. As(3+) increased the rate of transcription of both the Gclm and the Gclc genes and induced the posttranscriptional stabilization of Gclm mRNA. The antioxidant N-acetylcysteine abolished As(3+)-induced Gclc expression and attenuated induction of Gclm. As(3+) induction of Gclc and Gclm was also differentially regulated by the MAPK signaling pathways and occurred independent of the Nrf1/2 transcription factors. These findings demonstrate that distinct transcriptional and posttranscriptional mechanisms mediate the coordinate induction of the Gclc and Gclm subunits of GCL in response to As(3+) and highlight the potential importance of the GSH antioxidant defense system in regulating As(3+)-induced responses in hepatocytes.",
Arsenic,628676,"The relationship of arsenic levels in drinking water and the prevalence rate of skin lesions in Bangladesh Abstract: To determine the relationship of arsenic-associated skin lesions and degree of arsenic exposure, a cross-sectional study was conducted in Bangladesh, where a large part of the population is exposed through drinking water. Four villages in Bangladesh were identified as mainly dependent on wells contaminated with arsenic. We interviewed and examined 1,481 subjects Greater/equal to 30 years of age in these villages. A total of 430 subjects had skin lesions (keratosis, hyperpigmentation, or hypopigmentation) . Individual exposure assessment could only be estimated by present levels and in terms of a dose index, i.e., arsenic levels divided by individual body weight. Arsenic water concentrations ranged from 10 to 2,040 µg/L, and the crude overall prevalence rate for skin lesions was 29/100. After age adjustment to the world population the prevalence rate was 30.1/100 and 26.5/100 for males and females, respectively. There was a significant trend for the prevalence rate both in relation to exposure levels and to dose index (p < 0.05) , regardless of sex. This study shows a higher prevalence rate of arsenic skin lesions in males than females, with clear dose-response relationship. The overall high prevalence rate in the studied villages is an alarming sign of arsenic exposure and requires an urgent remedy.",
Arsenic,2343446,"Arsenic exposure increases maternal but not cord serum immunoglobulin G level in Bangladesh Abstract: <strong>BACKGROUND: </strong>Thousands of pregnant women are exposed to arsenic (As), which has been shown to lead to a higher risk of maternal and infant morbidity. We hypothesized that As-induced modifications to the humoral immune system may be partly responsible, and examined the relationship between As and immunoglobulin G (IgG) levels.<br /><br /><strong>METHODS: </strong>Pregnant women were recruited in As-contaminated rural areas in Bangladesh. Blood and urine samples, and questionnaire data were collected. We analyzed data from 202 pregnant women and a subset of 121 mother-infant pairs. Urinary-As was measured by inductively coupled plasma-mass spectrometry and adjusted with specific gravity (U-AsSG). Maternal (IgGmat) and cord (IgGcord) serum total IgG levels were measured by an immunoturbidity assay.<br /><br /><strong>RESULTS: </strong>The geometric mean U-AsSG (N = 202) was 69 ?g/L (range: 3.1-1356 ?g/L). Urinary-AsSG level was significantly associated with IgGmat (N = 202) (r = 0.24; 95% confidence interval = 0.10-0.36; P < 0.001) and remained so after the inclusion of maternal-associated variables in a multiple-regression model (? = 1.26; 95% confidence interval = 0.47-2.05; P < 0.01). However, U-AsSG level was not significantly associated with IgGcord level (N = 121), while IgGmat and IgGcord levels were also not associated.<br /><br /><strong>CONCLUSIONS: </strong>Maternal As exposure was positively associated with the IgGmat but not IgGcord level. An elevated IgGmat level may have implications as regards maternal morbidity and the placental transfer of specific IgGs. Further studies are required to better understand how As may affect maternal and child health by modifying the humoral immune system.",
Arsenic,1345182,"Occupational genotoxicity among copper smelters Abstract: Occupational exposure in a copper smelting industry may produce various adverse health effects including cancer. Despite a number of well-documented studies reporting an increased risk of cancer among copper smelter workers, the data on genotoxic effects in this industry are scarce. In view of the above, an assessment of DNA damage in peripheral blood leukocytes by Comet assay from copper smelter workers was undertaken. Additionally, the proton-induced X-ray emission (PIXE) analysis was assessed to determine the metal content of samples. The study was conducted with all workers from a copper smelter (males; n = 11), and a control group (n = 11) was recruited. The results of our study showed a significant increase (p &lt; 0.001; Mann-Whitney test) in DNA damage in peripheral blood lymphocytes of smelter workers, compared to the controls (p &lt; 0.001; Mann-Whitney test). No correlation between DNA damage or metal concentration and age mean or time of exposure was found under study. Our findings indicate that copper smelter workers have increased levels of DNA damage in somatic cells, suggesting a potential health risk for the workers. PIXE results show the presence of copper, iron, and other metals.",
Arsenic,1339039,"Characterisation of organic matter associated with groundwater arsenic in reducing aquifers of southwestern Taiwan Abstract: Arsenic (As) in groundwaters extensively used by people across the world constitutes a serious public health threat. The importance of organic matter (OM) as an electron donor in microbially-mediated reduction of As(V) or Fe(III)-bearing As-host minerals leading to mobilisation of solid-phase arsenic is widely recognised. Notwithstanding this, there are few studies characterising OM in such aquifers and, in particular, there is a dearth of data from the classic arsenic bearing aquifers in southwestern Taiwan. Organic geochemical analyses of sediments from a known groundwater arsenic hot-spot in southwestern Taiwan revealed contributions of thermally mature and plant derived origin, consistent with OM sources in all other Asian groundwater aquifer sediments analysed to date, indicating comparable sources and routes of OM transfer. The combined results of amended As(V) reduction assays with the organic geochemical analysis revealed that the microbiological process of dissimilatory As(V) reduction is active in this aquifer, but it is not controlled by a specific source of analysed OM. These indicate that (i) part of the OM that was considered to be less bio-available could still be used as an electron donor or (ii) other electron donors, not analysed in present study, could be controlling the rate of As release.",
Arsenic,2149169,"Chloride-catalyzed, multicomponent self-assembly of arsenic thiolates Abstract: We present the observation that chloride serves as a simple catalyst for the acceleration of a self-assembly reaction between AsCl3 and dithiolate ligands (H2L) to form As2L3 assemblies. Studies on a model monomeric arsenic complex suggest that chloride may accelerate ligand exchange dynamics in pnictogen thiolates in general.",
Arsenic,2337239,"Application of biochar to soil reduces cancer risk via rice consumption: A case study in Miaoqian village, Longyan, China Abstract: Consumption of rice contaminated with potentially toxic elements (PTEs) is a major pathway for human exposure to PTEs. This is particularly true in China's so called &quot;Cancer Villages&quot;. In this study, sewage sludge biochar (SSBC) was applied to soil (at 5% and 10%) to suppress PTE phytoavailability and as a consequence to reduce PTE levels in rice grown in mining impacted paddy soils. Risk assessment indicated that SSBC addition (10%) markedly (P?0.05) decreased the daily intake, associated with the consumption of rice, of PTEs (As, Cd, Co, Cu, Mn, Pb and Zn by: 68, 42, 55, 29, 43, 38 and 22%, respectively). In treatments containing SSBC (10%) the health quotient (HQ) indices for PTEs (except for As, Cu and Mn) were &lt;1, indicating that SSBC suppressed the health risk associated with PTEs in rice. The addition of SSBC (10%) markedly (P?0.01) reduced AsIII (72%), dimethylarsinic acid (DMA) (74%) and AsV (62%) concentrations in rice. Consequentially, following SSBC application (10%), the incremental lifetime cancer (ILTR) value for iAs (AsIII+AsV) associated with the consumption of rice was significantly (P?0.01) reduced by 66%. These findings suggest that SSBC could be a useful soil amendment to mitigating PTE exposure, through rice consumption, in China's &quot;Cancer Villages&quot;.",
Arsenic,1292194,"Transcriptomic changes and signalling pathways induced by arsenic stress in rice roots Abstract: Arsenic (As) is considered the most common toxic metalloid, but its molecular mode of action is not well understood. We investigated whether arsenate [As(V)] can induce intracellular reactive oxygen species production and calcium oscillation in rice roots. To better understand the molecular basis of plant cell responses to As, we performed a large-scale analysis of the rice transcriptome during As(V) stress. As(V) induced genes involved in abiotic stress, detoxification pathways and secondary metabolic process. Genes involved in secondary cell wall biogenesis, cell cycle and oligopeptide transport were mainly downregulated. Genes encoding signalling components such as receptor-like cytoplasmic kinases protein kinase, APETALA2/ethylene response factor, heat shock factor, MYB and zinc-finger protein expressed in inflorescence meristem transcription factors were increased in expression. The expression of GARP-G2-like and C3H transcription factors was specifically modulated by As(V) stress. The predominant families of As(V)-regulated transporters belonged to the ATP-binding cassette superfamily and telurite-resistance/dicarboxylate transporters. Several factors involved in signaling, such as mitogen-activated protein kinase (MAPK), MAPK kinase kinase and calcium-dependent protein kinase (CDPK), were also upregulated. Moreover, As(V) markedly increased the activity of MAPKs and CDPK-like kinases, and CDPK and NADPH oxidases were involved in As-induced MAPK activation. Further characterization of these As(V)-responsive genes and signalling pathways may help better understand the mechanisms of metalloid uptake, tolerance and detoxification in plants.",
Arsenic,1015836,"Effects of manganese and arsenic species on the level of energy related nucleotides in human cells Abstract: Cellular adenine and pyridine nucleotides play important roles in the cellular energy and redox state. An imbalance in the cellular levels of these tightly regulated energy related nucleotides can lead to oxidative stress and thus is discussed to contribute to neurotoxic and carcinogenic processes. Here we established a reliable ion-pair reversed phase HPLC based method for the parallel quantification of six energy related nucleotides (ATP, ADP, ADP-ribose, AMP, NAD(+), NADH) in cells and subsequently applied it to determine effects of manganese and arsenic species in cultured human cells. In human lung cells, MnCl(2) (?50 ?M) decreased the levels of ATP, NAD(+) and NADH as well as the NAD(+)/NADH ratio. This reflects a decline in the cellular energy metabolism, most likely resulting from a disturbance of the mitochondrial function. In contrast, cultured astrocytes were more resistant towards manganese. Regarding the arsenicals, a disturbance of the cellular energy related nucleotides was detected in lung cells for arsenite (?50 ?M), monomethylarsonous (?1 ?M), dimethylarsinous (?1 ?M) and dimethylarsinic acid (?100 ?M). Thereby, the single arsenicals seem to disturb the cellular energy and redox state by different mechanisms. Taken together, this study provides further evidence that cellular energy related nucleotides serve as sensitive indicators for toxic species exposure. When searching for a molecular mechanism of toxic compounds, the data illustrate the necessity of quantifying several energy related nucleotides in parallel, especially since ATP depletion, redox state alterations and oxidative stress are known to potentiate each other.",
Arsenic,1033127,"Localization of the vicinal dithiols involved in steroid binding to the rat glucocorticoid receptor Abstract: Our previous studies with the thiol-specific reagent methyl methanethiolsulfonate (MMTS) and the vicinal dithiol-specific reagent sodium arsenite have established that 2 spatially close thiols (i.e. vicinal dithiols) are involved in steroid binding to the intact 98 K rat glucocorticoid receptor. These 2 thiols form an intramolecular disulfide after treatment with low concentrations of MMTS. One of these thiols was proposed to by Cys-656. In an effort to identify both thiols, we have examined the effects of MMTS and arsenite on proteolytic fragments of the receptor, which contain progressively fewer cysteines. MMTS and arsenite are now found to cause the same dithiothreitol-reversible inhibition of steroid binding and affinity labeling of both the 42 K chymotrypsin fragment and the 16 K steroid-binding core fragment of the receptor as was seen for the intact receptor. Characteristic responses include a bimodal inhibition curve for steroid binding after preincubation with MMTS and an inhibition of binding by very low concentrations of arsenite. Low concentrations of MMTS could block steroid binding by forming a disulfide bond between the receptor and a tightly associated, nonreceptor protein. However, no evidence for such cross-linking was observed when intact 98 K receptors, 42 K chymotrypsin fragments, or 16 K trypsin fragments were treated with various concentrations of MMTS, separated on nonreducing sodium dodecyl sulfate-polyacrylamide gels, and visualized by Western blotting with antiheat shock protein 90 or antireceptor antibodies. One of the antireceptor antibodies (aP1) that had been raised against the rat receptor sequence 440-795 was now found to recognize at least 1 epitope in the 16 K core fragment. We conclude that the vicinal dithiols involved in steroid binding are 2 of the 3 cysteines in the sequence of Thr537-Arg673.",
Arsenic,628387,"Chronic arsenic exposure increases TGFalpha concentration in bladder urothelial cells of Mexican populations environmentally exposed to inorganic arsenic Abstract: Inorganic arsenic (iAs) is a well-established carcinogen and human exposure has been associated with a variety of cancers including those of skin, lung, and bladder. High expression of transforming growth factor alpha (TGF-alpha) has associated with local relapses in early stages of urinary bladder cancer. iAs exposures are at least in part determined by the rate of formation and composition of iAs metabolites (MAs(III), MAs(V), DMAs(III), DMAs(V)). This study examines the relationship between TGF-alpha concentration in exfoliated bladder urothelial cells (BUC) separated from urine and urinary arsenic species in 72 resident women (18-51 years old) from areas exposed to different concentrations of iAs in drinking water (2-378 ppb) in central Mexico. Urinary arsenic species, including trivalent methylated metabolites were measured by hydride generation atomic absorption spectrometry method. The concentration of TGF-alpha in BUC was measured using an ELISA assay. Results show a statistically significant positive correlation between TGF-alpha concentration in BUC and each of the six arsenic species present in urine. The multivariate linear regression analyses show that the increment of TGF-alpha levels in BUC was importantly associated with the presence of arsenic species after adjusting by age, and presence of urinary infection. People from areas with high arsenic exposure had a significantly higher TGF-alpha concentration in BUC than people from areas of low arsenic exposure (128.8 vs. 64.4 pg/mg protein; p<0.05). Notably, exfoliated cells isolated from individuals with skin lesions contained significantly greater amount of TGF-alpha than cells from individuals without skin lesions: 157.7 vs. 64.9 pg/mg protein (p=0.003). These results suggest that TGF-alpha in exfoliated BUC may serve as a susceptibility marker of adverse health effects on epithelial tissue in arsenic-endemic areas.",
Arsenic,2279204,"Association between arsenic exposure from drinking water and hematuria: Results from the Health Effects of Arsenic Longitudinal Study Abstract: Arsenic (As) exposure has been associated with both urologic malignancy and renal dysfunction; however, its association with hematuria is unknown. We evaluated the association between drinking water As exposure and hematuria in 7843 men enrolled in the Health Effects of Arsenic Longitudinal Study (HEALS). Cross-sectional analysis of baseline data was conducted with As exposure assessed in both well water and urinary As measurements, while hematuria was measured using urine dipstick. Prospective analyses with Cox proportional regression models were based on urinary As and dipstick measurements obtained biannually since baseline up to six years. At baseline, urinary As was significantly related to prevalence of hematuria (P-trend&lt;0.01), with increasing quintiles of exposure corresponding with respective prevalence odds ratios of 1.00 (reference), 1.29 (95% CI: 1.04-1.59), 1.41 (95% CI: 1.15-1.74), 1.46 (95% CI: 1.19-1.79), and 1.56 (95% CI: 1.27-1.91). Compared to those with relatively little absolute urinary As change during follow-up (-10.40 to 41.17?g/l), hazard ratios for hematuria were 0.99 (95% CI: 0.80-1.22) and 0.80 (95% CI: 0.65-0.99) for those whose urinary As decreased by &gt;47.49?g/l and 10.87 to 47.49?g/l since last visit, respectively, and 1.17 (95% CI: 0.94-1.45) and 1.36 (95% CI: 1.10-1.66) for those with between-visit increases of 10.40 to 41.17?g/l and &gt;41.17?g/l, respectively. These data indicate a positive association of As exposure with both prevalence and incidence of dipstick hematuria. This exposure effect appears modifiable by relatively short-term changes in drinking water As.",
Arsenic,1349638,"Regulation of metallothionein gene expression. Studies in transfected primary cultures of chick embryo liver cells Abstract: To study the regulation of expression of the metallothionein gene in normal liver cells, we transfected chick embryo liver cells in primary cultures with constructs containing luciferase or chloramphenicol acetyl transferase (as reporter genes) under the control of differing lengths of the 5'-promoter region of the chick metallothionein gene (containing 30, 122, 190, or 623 base pairs upstream of the transcriptional start site). We controlled for efficiency of transfection by co-transfections with a plasmid containing a bacterial beta-galactosidase gene under the control of the SV 40 promoter and enhancer. Treatment of the transfected cells with transition metallic ions (cadmium, cobalt, and zinc) or sodium arsenite produced increases in activities of luciferase or chloramphenicol acetyl transferase, relative to beta-galactosidase, and this activity mapped to the first 122 base pairs of the promoter. Although heme has recently been reported to induce the endogenous metallothionein gene in chick embryo liver cells, 10-50 microM heme did not increase reporter gene activities in transfected cells. Nevertheless, the heme-dependent induction of endogenous heme oxygenase-1 in these cells was normal. We conclude that the heme-dependent induction of the liver metallothionein gene depends upon DNA region(s) outside the regulatory region of the chick metallothionein gene studied here and that elements within the first 122 base pairs of the metallothionein promoter are sufficient to confer responsiveness to transition metals or sodium arsenite.",
Arsenic,2343570,"Sensitization of melanoma cells for TRAIL-induced apoptosis by activation of mitochondrial pathways via Bax Abstract: The death ligand TRAIL (TNF-related apoptosis-inducing ligand) represents a promising therapeutic strategy for metastatic melanoma, however prevalent and inducible resistance limits its applicability and therapeutic use. Recent work has revealed that combinations with survival pathway inhibitors could efficiently sensitize melanoma cells for TRAIL Here, a particular role was attributed to the activation of Bax, which is regulated by phosphorylation. Thus, TRAIL resistance in melanoma is explained by three major steps, namely high levels of antiapoptotic Bcl-2 proteins, high levels of inhibitor of apoptosis proteins (cIAPs) and suppressed Bax activity. Importantly, Bid was activated in response to TRAIL alone also in resistant cells to antagonize Bcl-2, and Bax was activated in response to pathway inhibitors. However, only in combinations, mitochondrial apoptosis pathways were opened to result in release of Smac/DIABLO, which functions as antagonist of cIAPs. Opening the caspase cascade by Smac then allowed efficient induction of apoptosis. Thus, direct or indirect targeting of Bax represents a suitable strategy to overcome TRAIL resistance in melanoma and may allow the establishment of TRAIL-based therapeutic approaches. (C) 2013 Elsevier GmbH. All rights reserved.",
Arsenic,1337263,"Physiological profile of elite Chinese female wrestlers Abstract: The purpose of this investigation was to describe the physiological profile of elite senior Chinese female wrestlers. Twenty-five elite wrestlers, nationally ranked in the top 3 of their weight class, participated in the study. The subjects included Olympic and world champion medalists. The physiological profile included testing of running maximal oxygen consumption (VO2max), 3,200-m run time, 400-m run time, 30-second Wingate anaerobic power and capacity, shoulder, elbow, knee and trunk isokinetic torque, and one repetition maximums (1RMs) in specified exercises. The major results (mean ± SD) were VO2max: 50.58 ± 3.33 ml kg-1 min-1; 3,200-m run: 14.1 min ± 0.49 s; 400-m run: 1 min 11 s ± 4 s; Wingate maximal anaerobic power: 495.21 ± 79.13 W and mean power: 262.97 ± 52.39 W; 1RM dead lift: 124 ± 19 kg; 1RM deep squat: 98 ± 11 kg; 1RM prone rowing: 72 ± 8 kg; 1RM power clean: 76 ± 12 kg; and 1RM hold and squat: 109 ± 17 kg. In absolute terms in the majority of measures the heavier weight classes had greater values than the lighter weight classes, but relative to body mass there were few differences in measures between weight classes. In most measures the best value was that of an Olympic and/or world championship medalist. The results indicate female wrestling success is not dependent upon one physiological characteristic, but that a variety of physiological profiles can result in success. This data on elite female wrestlers can be compared to other wrestlers to help determine individual weaknesses or strengths, and to design training programs that result in wrestling success.",
Arsenic,1021811,"In vitro evaluation of co-exposure of arsenium and an organic nanomaterial (fullerene, C??) in zebrafish hepatocytes Abstract: Taking into account the concept of the Trojan Horse, where contaminants may have its entry into specific organs potentiated by its association with nanomaterials, the aim of this study was to analyze the joint toxic effects induced by an organic nanomaterial, fullerene (C(60)) with the metalloid arsenic (As(III)). Hepatocytes of zebrafish Danio rerio were exposed to As(III) (2.5 or 100 ?M), C(60) or As+C(60) for 4h, not altering cells viability. Intracellular reactive oxygen species concentration was reduced in cells exposed only to the C(60) (1mg/L) and in the treatment of 100 ?M As(III)+C(60). Co-exposure with C(60) abolished the peak of the antioxidant glutathione (GSH) registered in cells exposed to the lowest As(III) concentration (2.5 ?M). A similar result was observed in terms of lipid damage (TBARS). Total antioxidant capacity was significantly higher at both As(III) concentrations co-exposed to C(60) when compared with the control group. Activity of glutathione-S-transferase omega, a limiting enzyme in the methylation pathway of As(III), was reduced in the 100 ?M As(III)+C(60) treatment. Cells co-exposed to C(60) had a significantly higher accumulation of As(III), showing a Trojan Horse effect which did not result in higher cell toxicity. Instead, co-exposure of As(III) with C(60) showed to reduce cellular injury.",
Arsenic,1579314,"Microbial transformations of arsenic: Perspectives for biological removal of arsenic from water Abstract: Arsenic is present in many environments and is released by various natural processes and anthropogenic actions. Although arsenic is recognized to cause a wide range of adverse health effects in humans, diverse bacteria can metabolize it by detoxification and energy conservation reactions. This review highlights the current understanding of the ecology, biochemistry and genomics of these bacteria, and their potential application in the treatment of arsenic-polluted water.",
Arsenic,627326,"Arsenic levels in ground water and cancer incidence in Idaho: An ecologic study Abstract: PURPOSE: Long-term exposure to arsenic above 50 microg/L in drinking water has been related to multiple types of cancers. Few epidemiologic studies conducted in the US have detected an association between regional exposures below this level in drinking water and corresponding cancer occurrence rates. This county-level ecologic study evaluates arsenic levels in ground water and its association with targeted cancer incidence in Idaho, where some regions have been found to contain higher arsenic levels. METHODS: Using cancer incidence data (1991-2005) from the Cancer Data Registry of Idaho and arsenic data (1991-2005) from the Idaho Department of Environmental Quality, we calculated the age-adjusted incidence rate for cancers of the urinary bladder, kidney and renal pelvis, liver and bile duct, lung and bronchus, non-Hodgkin's lymphoma (NHL), and all malignant cancers according to arsenic levels in ground water. Multivariate regression analysis was applied to evaluate the relationship between arsenic levels in ground water and cancer incidence. RESULTS: For males, but not for females, age-adjusted incidence for lung cancer and all malignant cancers was significantly higher in the intermediate arsenic counties (2-9 microg/L, n = 16) and the high arsenic counties (>or=10 microg/L, n = 5) compared to the low arsenic counties (<2.0 microg/L, n = 23). When adjusted for race, gender, population density, smoking and body mass index (BMI), no relationship was found between arsenic levels in ground water and cancer incidence. CONCLUSIONS: In this ecological design, exposure to low-level arsenic in ground water is not associated with cancer incidence when adjusting for salient variables. For populations residing in southwestern Idaho, where arsenic has been found to exceed 10 microg/L in ground water, individual risk assessment is required in order to determine whether there is a link between long-term arsenic exposure at these levels and cancer risk.",
Arsenic,1031747,"Activation of heme oxygenase and heat shock protein 70 genes by stress in human hepatoma cells Abstract: Effects of various stresses were examined on the accumulation of mRNA for microsomal heme oxygenase and a heat shock protein, hsp70, in three human hepatoma cell lines. By heat shock, hsp70 mRNA was induced in all three hepatoma lines, Hep G2, Hep 3B and Hep G2f, while heme oxygenase mRNA was increased only in Hep 3B. Time-courses of the heat shock induction of both mRNAs in Hep 3B were similar. Arsenite caused induction of both mRNAs in all three cell lines, while cadmium increased them in Hep G2 and Hep 3B, but not in Hep G2f cells. These findings suggest that, although both hsp70 and heme oxygenase are heat shock proteins, the mode of induction of mRNAs for these proteins is different.",
Arsenic,1017763,"Transition metal ions and selenite modulate the methylation of arsenite by the recombinant human arsenic (+3 oxidation state) methyltransferase (hAS3MT) Abstract: This report demonstrates that transition metal ions and selenite affect the arsenite methylation by the recombinant human arsenic (+3 oxidation state) methyltransferase (hAS3MT) in vitro. Co(2+), Mn(2+), and Zn(2+) inhibited the arsenite methylation by hAS3MT in a concentration-dependent manner and the kinetics indicated Co(2+) and Mn(2+) to be mixed (competitive and non-competitive) inhibitors while Zn(2+) to be a competitive inhibitor. However, only a high concentration of Fe(2+) could restrain the methylation. UV-visible, CD and fluorescence spectroscopy were used to study the interactions between the metal ions above and hAS3MT. Further studies showed that neither superoxide anion nor hydrogen peroxide was involved in the transition metal ion or selenite inhibition of hAS3MT activity. The inhibition of arsenite methylating activity of hAS3MT by selenite was reversed by 2mM DTT (dithiothreitol) but neither by cysteine nor by beta-mercaptoethanol. Whereas, besides DTT, cysteine can also prevent the inhibition of hAS3MT activity by Co(2+), Mn(2+), and Zn(2+). Free Cys residues were involved in the interactions of transition metal ions or selenite with hAS3MT. It is proposed that the inhibitory effect of the ions (Co(2+), Mn(2+), and Zn(2+)) or selenite on hAS3MT activity might be via the interactions of them with free Cys residues in hAS3MT to form inactive protein adducts.",
Arsenic,2298744,"Arsenic transforming abilities of groundwater bacteria and the combined use of Aliihoeflea sp. strain 2WW and goethite in metalloid removal Abstract: Several technologies have been developed for lowering arsenic in drinking waters below the World Health Organization limit of 10?g/L. When in the presence of the reduced form of inorganic arsenic, i.e. arsenite, one options is pre-oxidation of arsenite to arsenate and adsorption on iron-based materials. Microbial oxidation of arsenite is considered a sustainable alternative to the chemical oxidants. In this contest, the present study investigates arsenic redox transformation abilities of bacterial strains in reductive groundwater from Lombardia (Italy), where arsenite was the main arsenic species. Twenty isolates were able to reduce 75mg/L arsenate to arsenite, and they were affiliated to the genera Pseudomonas, Achromobacter and Rhodococcus and genes of the ars operon were detected. Three arsenite oxidizing strains were isolated: they belonged to Rhodococcus sp., Achromobacter sp. and Aliihoeflea sp., and aioA genes for arsenite oxidase were detected in Aliihoeflea sp. strain 2WW and in Achromobacter sp. strain 1L. Uninduced resting cells of strain 2WW were used in combination with goethite for arsenic removal in a model system, in order to test the feasibility of an arsenic removal process. In the presence of 200?g/L arsenite, the combined 2WW-goethite system removed 95% of arsenic, thus lowering it to 8?g/L. These results indicate that arsenite oxidation by strain 2WW combined to goethite adsorption is a promising approach for arsenic removal from contaminated groundwater.",
Arsenic,1797745,"Archaeal and bacterial diversity in an arsenic-rich shallow-sea hydrothermal system undergoing phase separation Abstract: Phase separation is a ubiquitous process in seafloor hydrothermal vents, creating a large range of salinities. Toxic elements (e.g., arsenic) partition into the vapor phase, and thus can be enriched in both high and low salinity fluids. However, investigations of microbial diversity at sites associated with phase separation are rare. We evaluated prokaryotic diversity in arsenic-rich shallow-sea vents off Milos Island (Greece) by comparative analysis of 16S rRNA clone sequences from two vent sites with similar pH and temperature but marked differences in salinity. Clone sequences were also obtained for aioA-like functional genes (AFGs). Bacteria in the surface sediments (0-1.5 cm) at the high salinity site consisted of mainly Epsilonproteobacteria (Arcobacter sp.), which transitioned to almost exclusively Firmicutes (Bacillus sp.) at ~10 cm depth. However, the low salinity site consisted of Bacteroidetes (Flavobacteria) in the surface and Epsilonproteobacteria (Arcobacter sp.) at ~10 cm depth. Archaea in the high salinity surface sediments were dominated by the orders Archaeoglobales and Thermococcales, transitioning to Thermoproteales and Desulfurococcales (Staphylothermus sp.) in the deeper sediments. In contrast, the low salinity site was dominated by Thermoplasmatales in the surface and Thermoproteales at depth. Similarities in gas and redox chemistry suggest that salinity and/or arsenic concentrations may select for microbial communities that can tolerate these parameters. Many of the archaeal 16S rRNA sequences contained inserts, possibly introns, including members of the Euryarchaeota. Clones containing AFGs affiliated with either Alpha- or Betaproteobacteria, although most were only distantly related to published representatives. Most clones (89%) originated from the deeper layer of the low salinity, highest arsenic site. This is the only sample with overlap in 16S rRNA data, suggesting arsenotrophy as an important metabolism in similar environments.",
Arsenic,1024647,"Identification of arsenic-binding proteins in human breast cancer cells Abstract: As a cancer chemotherapeutic drug, arsenic acts on numerous intracellular signal transduction pathways in cancer cells. However, its mechanism of actions is still not fully understood. Previous studies suggest that arsenic reacts with closely spaced cysteine (Cys) residues of proteins with high Cys content and accessible sulfhydryl (SH) groups. In this study, human breast cancer cell line MCF-7 was examined as a cellular model to explore arsenic-binding proteins and the mechanism of binding. An arsenic-biotin conjugate was synthesized by coupling the pentafluorophenol ester of biotin with p-aminophenylarsenoxide. Arsenic-binding proteins were eluted with streptavidin resin from arsenic-biotin treated MCF-7 cells, separated by polyacrylamide gel electrophoresis, and identified by matrix assisted laser desorption ionization mass spectrometry (MALDI-MS). Arsenic-binding properties of two of these proteins, beta-tubulin and pyruvate kinase M2 (PKM2), were studied further in vitro and the biological consequences of this binding was evaluated. Binding assay with Western blotting confirmed binding of beta-tubulin and PKM2 by arsenic in a concentration-dependent manner. Arsenic binding inhibited tubulin polymerization, but surprisingly had no effect on PKM2 activity. Molecular modeling showed that binding of Cys(12) alone or vicinal Cys residues (Cys(12) and Cys(213)) of beta-tubulin by arsenic blocked the active site for access of GTP, which is necessary for tubulin polymerization. On the contrary, all Cys residues of PKM2 were far away from the active site of the enzyme. In summary, this study confirmed beta-tubulin and PKM2 as arsenic-binding proteins in MCF-7 cells. Functional consequence of such binding may depend on whether arsenic binding causes conformational changes or blocks active sites of target proteins.",
Arsenic,1337290,"Monte Carlo-based evaluation of S-values in mouse models for positron-emitting radionuclides Abstract: In addition to being a powerful clinical tool, Positron emission tomography (PET) is also used in small laboratory animal research to visualize and track certain molecular processes associated with diseases such as cancer, heart disease and neurological disorders in living small animal models of disease. However, dosimetric characteristics in small animal PET imaging are usually overlooked, though the radiation dose may not be negligible. In this work, we constructed 17 mouse models of different body mass and size based on the realistic four-dimensional MOBY mouse model. Particle (photons, electrons and positrons) transport using the Monte Carlo method was performed to calculate the absorbed fractions and S-values for eight positron-emitting radionuclides (C-11, N-13, O-15, F-18, Cu-64, Ga-68, Y-86 and I-124). Among these radionuclides, O-15 emits positrons with high energy and frequency and produces the highest self-absorbed S-values in each organ, while Y-86 emits ?-rays with high energy and frequency which results in the highest cross-absorbed S-values for non-neighbouring organs. Differences between S-values for self-irradiated organs were between 2% and 3%/g difference in body weight for most organs. For organs irradiating other organs outside the splanchnocoele (i.e. brain, testis and bladder), differences between S-values were lower than 1%/g. These appealing results can be used to assess variations in small animal dosimetry as a function of total-body mass. The generated database of S-values for various radionuclides can be used in the assessment of radiation dose to mice from different radiotracers in small animal PET experiments, thus offering quantitative figures for comparative dosimetry research in small animal models.",
Arsenic,1025342,"Arsenic and metaldehyde toxicosis in a beef herd Abstract: Over a 12-day period, 13 animals in a herd of 110 beef cattle developed ataxia with profound muscle fasciculations progressing to recumbency. Twelve animals (5 adults and 7 calves from 8-10 months of age) died, and 1 cow was euthanized. Hemorrhagic diarrhea occurred in some, but not all, animals. The onset of clinical signs was at least 12 hours after the cattle had gained access to contents of old buildings used for storage, and the majority of deaths occurred within 24 to 48 hours after the onset of clinical signs. Approximately 9 kg of unidentified pellets were found strewn in the barn area where the cattle had been. Autolysis considered more severe than expected for the postmortem interval, suggestive of high body temperature before death, and congestion of body tissues were the only significant findings detected in the cow that was euthanized and submitted for necropsy examination. The clinical history and lack of postmortem lesions were most consistent with toxicity. A toxic level of arsenic (6.18 ppm) was detected in the kidney, and metaldehyde was detected in the liver. The pellets were analyzed and found to contain both arsenic and metaldehyde, consistent with a discontinued molluscicidal product.",
Arsenic,1026156,"Nondestructive identification of arsenic and cobalt minerals from Cobalt City, Ontario, Canada: Arsenolite, erythrite, and spherocobaltite on pararammelsbergite Abstract: A Ni-Co-As ore sample from Cobalt City, Ontario, Canada, was examined with scanning electron microscopy and energy dispersive X-ray analysis. In addition to cobaltian pararammelsbergite with variable cobalt content, for which Cobalt City is the type locality, and erythrite, one new mineral was observed for this locality. Well-formed crystals of arsenolite, As(2)O(3), were found embedded in what appears to be fibrous spherocobaltite, CoCO(3). Additional information was obtained by Raman microscopy, confirming the identification of the arsenolite. Both are considered to be secondary minerals formed by exposure to air resulting in oxidation and the formation of secondary carbonates.",
Arsenic,1018446,"Interaction of arsenic(III) with nucleotide excision repair in UV-irradiated human fibroblasts Abstract: Even though epidemiological studies have identified arsenic compounds as carcinogenic to humans, they are not mutagenic in bacterial and mammalian test systems. However, they increase the mutagenicity and clastogenicity in combination with other DNA damaging agents and there are indications of inhibition of DNA repair processes. We investigated the effect of arsenic(III) on nucleotide excision repair (NER) after UV irradiation in human fibroblasts in detail by using two repair-proficient and one partly repair-deficient xeroderma pigmentosum group C human fibroblast cell lines. The results show that two steps of NER are affected by arsenite. Most severely, the incision frequency is reduced at concentrations as low as 2.5 microM arsenic(III); at higher, cytotoxic concentrations, the ligation of repair patches is also impaired. Furthermore, our results indicate that both the global genome repair pathway and the transcription-coupled repair pathway are affected by arsenite. Repair inhibition may well explain the potentiation of genotoxic effects by arsenic in combination with other DNA damaging agents and may thus be of high relevance for the carcinogenic action of arsenic compounds.",
Arsenic,8522,"Effects of arsenic, selenium, and chromium on the fidelity of DNA synthesis Abstract: #The effect of three environmentally important metals, arsenic, selenium, and chromium, on the accuracy of DNA synthesis in vitro has been analyzed. The addition of arsenic to fidelity assays did not significantly alter accuracy. Selenium did not alter fidelity under normal conditions of magnesium activation, nor did it affect the mutagenicity of manganese. Chromium in the form of Cr(III) as well as Cr(VI) diminished the fidelity by which Escherichia coli DNA polymerase I copies polynucleotide templates. Nearest-neighbor analysis of the product synthesized in the presence of chromium indicates that the misincorporated bases are present as single-base substitutions. Chromium was also mutagenic using the recently developed ""Phi""""Chi""174 assay, which measures the fidelity of DNA synthesis with a natural DNA template.",
Arsenic,1519145,"An XPS study on the valence states of arsenic in arsenian pyrite: Implications for Au deposition mechanism of the Yang-shan Carlin-type gold deposit, western Qinling belt Abstract: ",
Arsenic,2064283,"An update on oxidative stress-mediated organ pathophysiology Abstract: Exposure to environmental pollutants and drugs can result in pathophysiological situations in the body. Research in this area is essential as the knowledge on cellular survival and death would help in designing effective therapeutic strategies that are needed for the maintenance of the normal physiological functions of the body. In this regard, naturally occurring bio-molecules can be considered as potential therapeutic targets as they are normally available in commonly consumed foodstuffs and are thought to have minimum side effects. This review article describes the detailed mechanisms of oxidative stress-mediated organ pathophysiology and the ultimate fate of the cells either to survive or to undergo necrotic or apoptotic death. The mechanisms underlying the beneficial role of a number of naturally occurring bioactive molecules in oxidative stress-mediated organ pathophysiology have also been included in the review. The review provides useful information about the recent progress in understanding the mechanism(s) of various types of organ pathophysiology, the complex cross-talk between these pathways, as well as their modulation in stressed conditions. Additionally, it suggests possible therapeutic applications of a number of naturally occurring bioactive molecules in conditions involving oxidative stress.",
Arsenic,1797809,"Environmental tobacco smoke and arsenic methylation capacity are associated with urothelial carcinoma Abstract: <strong>BACKGROUND/PURPOSE: </strong>Cigarette smoking, exposure to secondhand smoke, and arsenic exposure are well known risk factors for developing urothelial carcinoma (UC). We investigated the combined effects of cigarette smoking, exposure to secondhand smoke, and the presence of urinary total arsenic on the risk of developing UC.<br /><br /><strong>MATERIALS AND METHODS: </strong>We conducted a hospital-based, case-control study involving 261 UC patients and 672 cancer-free control individuals between September 2002 and May 2009.<br /><br /><strong>RESULTS: </strong>Individuals who had smoked &lt;100 cigarettes in their lifetime (never smokers) and had a high urinary total arsenic level (?15.40 ?g/g creatinine), and those who had smoked &gt;100 cigarettes in their lifetime (ever smokers) and had a high urinary total arsenic level, had increased risks of developing UC (3.20-fold and 6.45-fold greater), respectively, compared to individuals who were never smokers and had a low urinary total arsenic level. Individuals who had high urinary total arsenic levels and had been exposed to secondhand smoke, and individuals with high urinary arsenic levels who had not been exposed to secondhand smoke, had increased chances (2.71-fold and 5.00-fold greater, respectively) of developing UC, compared to individuals who were not exposed to secondhand smoke and had low urinary total arsenic levels. Ever smokers who had been exposed to secondhand smoke and had a high urinary total arsenic level had the greatest increased risk for developing UC (10.82-fold greater).<br /><br /><strong>CONCLUSION: </strong>Individuals in a Taiwanese population who smoked cigarettes, were exposed to secondhand smoke, and a high urinary total arsenic level, had a significant risk for developing UC.",
Arsenic,628566,"Gene expression of inflammatory molecules in circulating lymphocytes from arsenic-exposed human subjects Abstract: Long-term arsenic exposure is associated with an increased risk of vascular diseases including ischemic heart disease, cerebrovascular disease, and carotid atherosclerosis. The pathogenic mechanisms of arsenic atherogenicity are not completely clear. A fundamental role for inflammation in atherosclerosis and its complications has become appreciated recently. To investigate molecular targets of inflammatory pathway possibly involved in arsenic-associated atherosclerosis, we conducted an exploratory study using cDNA microarray and enzyme-linked immunosorbent assay to identify genes with differential expression in arsenic-exposed yet apparently healthy individuals. As an initial experiment, array hybridization was performed with mRNA isolated from activated lymphocytes of 24 study subjects with low (0-4.32 microg/L), intermediate (4.64-9.00 microg/L), and high (9.60-46.5 microg/L) levels of blood arsenic, with each group comprising eight age-, sex-, and smoking frequency-matched individuals. A total of 708 transcripts of known human genes were analyzed, and 62 transcripts (8.8%) showed significant differences in the intermediate or high-arsenic groups compared with the low-level arsenic group. Among the significantly altered genes, several cytokines and growth factors involving inflammation, including interleukin-1 beta, interleukin-6, chemokine C-C motif ligand 2/monocyte chemotactic protein-1 (CCL2/MCP1), chemokine C-X-C motif ligand 1/growth-related oncogene alpha, chemokine C-X-C motif ligand 2/growth-related oncogene beta, CD14 antigen, and matrix metalloproteinase 1 (interstitial collagenase) were upregulated in persons with increased arsenic exposure. Multivariate analyses on 64 study subjects of varying arsenic exposure levels showed that the association of CCL2/MCP1 plasma protein level with blood arsenic remained significant after adjustment for other risk factors of cardiovascular diseases. The results of this gene expression study indicate that the expression of inflammatory molecules may be increased in human subjects after prolonged exposure to arsenic, which might be a contributory factor to the high risk of atherosclerosis in arseniasis-endemic areas in Taiwan. Further multidisciplinary studies, including molecular epidemiologic investigations, are needed to elucidate the role of arsenic-associated inflammation in the development of atherosclerosis and subsequent cardiovascular disease.",1
Arsenic,1704058,ARSENIC SPECIATION IN TYPICAL SURFACE SOILS FROM MINING AREAS IN THE SOUTHEAST OF HUBEI PROVINCE Abstract: ,
Arsenic,1020054,"Arsenic-induced Mre11 phosphorylation is cell cycle-dependent and defective in NBS cells Abstract: Cancer-prone diseases ataxia-telangiectasia (AT), Nijmegen breakage syndrome (NBS) and ataxia-telangiectasia-like disorder (ATLD) are defective in the repair of DNA double-stranded break (DSB). On the other hand, arsenic (As) has been reported to cause DSB and to be involved in the occurrence of skin, lung and bladder cancers. To dissect the repair mechanism of As-induced DSB, wild type, AT and NBS cells were treated with sodium arsenite to study the complex formation and post-translational modification of Rad50/NBS1/Mre11 repair proteins. Our results showed that Mre11 went through cell cycle-dependent phosphorylation upon sodium arsenite treatment and this post-translational modification required NBS1 but not ATM. Defective As-induced Mre11 phosphorylation was rescued by reconstitution with full length NBS1 in NBS cells. Although As-induced Mre11 phosphorylation was not required for Rad50/NBS1/Mre11 complex formation, it might be required for the formation of Rad50/NBS1/Mre11 nuclear foci upon DNA damage.",
Arsenic,1677610,"Arsenic-Bearing Calcite in Natural Travertines: Evidence from Sequential Extraction, ?XAS, and ?XRF Abstract: Recent studies demonstrated that synthetic calcite may host considerable amounts of arsenic (As). In this paper, the concentration of As in natural calcite was determined using two novel, specifically designed, sequential extraction procedures. In addition, the oxidation state of As and its distribution between calcite and coexisting Fe-oxyhydroxides was unravelled by ?XRF elemental mapping and As K-edge ?XAS spectroscopy. Our results conclusively demonstrate that arsenic can be found in natural calcite up to 2 orders of magnitude over the normal crustal As abundances. Because of the large diffusion of calcite in the environment, this phase may exert an important control on As geochemistry, mobility, and bioavailability.",
Arsenic,1252602,"Non-Hodgkin's lymphoma and exposure to phenoxyherbicides, chlorophenols, fencing work, and meat works employment: A case-control study Abstract: A previous case-control study which used the occupational information available on the New Zealand Cancer Registry found that agricultural workers were at increased risk of developing non-Hodgkin's lymphoma. The findings are now presented for the second phase of the study which entailed interviewing 83 cases of non-Hodgkin's lymphoma registered under code 202 of the International Classification of Diseases together with 168 controls with other types of cancer and 228 general population controls. The findings for the two control groups were similar, and there were no significant differences between cases and controls regarding potential exposure to phenoxy-herbicides (odds ratio = 1.4, 90% confidence limits 0.7-2.5, p = 0.26) or chlorophenols (odds ratio = 1.3, 90% confidence limits 0.6-2.7, p = 0.39). The odds ratio for fencing work, necessitating exposure to several potential risk factors including arsenic and sodium pentachlorophenate was 2.0 (90% confidence limits 1.3-3.0, p = 0.01). The odds ratio for employment in a meat works, necessitating potential exposure to 2, 4, 6-trichlorophenol and zoonotic viruses, was 1.8 (90% confidence limits 1.1-3.1, p = 0.04). There was a significant statistical interaction between the risks associated with these two activities, the odds ratio for involvement in both activities compared with involvement in neither being 5.7 (90% confidence limits 2.3-14.3, p = 0.03).",
Arsenic,1350677,"Immobilization of arsenic(V) during the transformation of ferrihydrite: A direct speciation study using synchrotron-based XAFS spectroscopy Abstract: In the present study, we investigated the behavior of arsenic (As) during the transformation of poorly crystalline iron(III) hydroxide, ferrihydrite. Adsorbed As on solids gradually decreased as ferrihydrite transformed to crystalline goethite and hematite. X-ray absorption fine structure (XAFS) analysis indicated that the As immobilization dominantly resulted from the incorporation of arsenate into poorly crystalline ferrihydrite under present experimental conditions.",
Arsenic,1519073,"Arsenite elicits anomalous sulfur starvation responses in barley Abstract: Treatment of barley (Hordeum vulgare) seedlings with arsenite (AsIII) rapidly induced physiological and transcriptional changes characteristic of S deficiency, even in plants replete with S. AsIII and S deficiency induced 5 - 20 fold increases in the three genes responsible for sulfate reduction. Both treatments also caused upregulation of a sulfate transporter, but only in the case of S deficiency was there an increase in sulfate influx. Longer term changes included reduction in transfer of S from roots to shoots, and an increase in root growth relative to shoot growth. Genes involved in complexation and compartmentation of As were upregulated by AsIII but not by S-deficiency. The rate at which As accumulated appeared to be controlled by the rate of thiol synthesis. Over a range of AsIII concentrations and growth periods, the ratio of thiols to As was always close to 3:1, which is consistent with the formation of a stable GS3:AsIII complex.The greater toxicity of As under S-limiting conditions is likely to be due to an intensification of S deficiency as a result of thiol synthesis rather than to a direct toxicity to metabolism. Since influx of AsIII was nearly 20-fold faster than the rate of synthesis of thiols, it is questionable whether this complexation strategy can be effective in preventing As toxicity unless As uptake becomes limited by diffusive resistances in the rhizosphere.",
Arsenic,2149140,Rapid in situ identification of arsenic species using a portable Fe3O4@Ag SERS sensor Abstract: Rapid and sensitive SERS identification and quantification of arsenic species in multiple matrices have been realized using a Fe3O4@Ag magnetic substrate. The molecular structure of arsenic on Fe3O4@Ag characterized using EXAFS spectroscopy and DFT confirms the existence of a chemical effect on SERS enhancement.,
Arsenic,2278777,"A different sequence of events than previously reported leads to arsenic-induced damage in Ceratophyllum demersum L Abstract: Arsenic (As) is a common pollutant, and still many questions remain concerning As toxicity mechanisms under environmentally relevant conditions in plants. Here we investigated thresholds and interactions of various proposed As toxicity mechanisms. Experiments were done under environmentally pertinent conditions in the rootless aquatic macrophyte Ceratophyllum demersum L., a model for plant shoots. Arsenic (provided as As(v)) inhibited plant metabolism at much lower concentrations and with a different sequence of events than previously reported. The first observed effect of toxicity was a decrease in pigment concentration, it started even at 0.5 ?M As. In contrast to toxic metals, no inhibition of the photosystem II reaction centre (PSIIRC; measured as Fv/Fm) was found at sublethal As concentrations. Instead, the decrease in light harvesting pigments caused a less efficient exciton transfer towards the PSIIRC. At higher As concentrations this led to increased non-photochemical quenching (NPQ) by light harvesting complex II (LHCII). Afterwards, photosynthetic electron transport decreased, but the increase in starch content indicated stronger inhibition of starch consumption than production. At lethal As concentration, photosynthesis was completely inhibited, its malfunction caused oxidative stress and not the other way round as reported previously. Photosynthesis was inhibited before any sign of oxidative stress was observed. Elevated phosphate drastically shifted thresholds of lethal As effects, not only by the known uptake competition but also by modifying uptake regulation and intracellular processes.",
Arsenic,1357035,"Comparative effects of essential and nonessential metals on preimplantation mouse embryo development Abstract: It is well recognized that deficiencies of essential trace elements during early development can result in structural abnormalities and/or embryonic death. Recently, there has been increasing interest in the concept that small excesses of essential minerals may also have negative effects on the developing embryo. We hypothesize that, with respect to toxicity, metals with similar physico-chemical properties would act by similar mechanisms to influence the preimplantation embryo. In the current study we investigated the influence of four essential (Cu, Mn, Fe, Zn), and eight nonessential (Cr, Hg, Pb, V, Al, Ag, Cd, As) minerals on mouse preimplantation embryonic development. Two cell stage mouse embryos were cultured for 72 h in media containing varying mineral concentrations (0.05-200 uM). Developmental kinetic data were collected throughout the culture period; embryo cell number was assessed at the end of the culture period. Both nonessential and essential metals were observed to be embryotoxic at relatively low concentrations. However, in contrast to our prediction, at similar molar concentrations, redox active essential minerals were less toxic than non-redox active nonessential minerals. These data suggest that direct metal binding to critical membrane sites and/or intracellular ligands, including protein and nucleic acids, may trigger abnormal development and death prior to metal associated oxidative damage.",
Arsenic,1021776,"Aberrant immune responses in arsenical skin cancers Abstract: Arsenic is a well-known human carcinogen. It also impairs immune functions and activation in many aspects. However, only a small portion of arsenic-exposed population develops skin abnormalities, including Bowen's disease and skin cancers. Differential immune activation among the individuals might account for the different susceptibilities. In patients with arsenic-induced Bowen's disease, there is a selective CD4 T-cell apoptosis through tumor necrosis factor-alpha pathway, decrease in macrophage differentiation and phagocytosis, reduced Langerhans cell numbers and dendrites, altered regulatory T-cell distribution, and other immune alterations. Several lines of evidence from mouse and fish studies also confirmed the potent and multifaceted effects of arsenic in the immune system. The molecular bases of immunosuppression by arsenic in lymphocytes may include chromosomal and DNA abnormalities, decreased T-cell receptor activation, and the cellular status of oxidation and methylation. This article also reviews the causative and differential role of selective CD4 cell apoptosis and the carcinogenesis of arsenic-induced Bowen's disease.",
Arsenic,1021872,"Inference for causal interactions for continuous exposures under dichotomization Abstract: Dichotomization of continuous exposure variables is a common practice in medical and epidemiological research. The practice has been cautioned against on the grounds of efficiency and bias. Here we consider the consequences of dichotomization of a continuous covariate for the study of interactions. We show that when a continuous exposure has been dichotomized certain inferences concerning causal interactions can be drawn with regard to the original continuous exposure scale. Within the context of interaction analyses, dichotomization and the use of the results in this article can furthermore help prevent incorrect conclusions about the presence of interactions that result simply from erroneous modeling of the exposure variables. By considering different dichotomization points one can gain considerable insight concerning the presence of causal interaction between exposures at different levels. The results in this article are applied to a study of the interactive effects between smoking and arsenic exposure from well water in producing skin lesions.",
Arsenic,1371921,ARSENITE AS THE PROBABLE ACTIVE SPECIES IN THE HUMAN CARCINOGENICITY OF ARSENIC MOUSE MICRONUCLEUS ASSAYS ON SODIUM AND POTASSIUM ARSENITE ORPIMENT AND FOWLER'S SOLUTION Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN LUNG CANCER SKIN CANCER GENOTOXIN ANALYTICAL METHOD,
Arsenic,2278612,"Solubility and disintegration of new calcium aluminate cement (EndoBinder) containing different radiopacifying agents Abstract: <strong>INTRODUCTION: </strong>The aim of this study was to evaluate the solubility and disintegration of EndoBinder (EB) containing 3 different radiopacifying agents, bismuth oxide (Bi2O3), zinc oxide (ZnO), or zirconium oxide (ZrO2), in comparison with gray mineral trioxide aggregate (GMTA) and white MTA (WMTA).<br /><br /><strong>METHODS: </strong>Ten specimens of each cement were made in a stainless steel matrix (20 × 1.5 mm) according to Specification no. 57 of American National Standards Institute/American Dental Association: EB + Bi2O3, EB + ZrO, EB + ZnO, WMTA, and GMTA. The specimens were weighed on an accurate analytical scale and immersed in 50 mL distilled and deionized water at 37°C for 7 days. Afterwards, specimens were dried and weighed again to determine mass loss (%). Resulting solutions were analyzed in an atomic absorption spectrophotometer for identification and quantification of chemical elements released.<br /><br /><strong>RESULTS: </strong>All cements presented mean values of solubility and disintegration above the American National Standards Institute/American Dental Association Specification no. 57. EB + Bi2O3 presented the lowest mass loss (5.08%) and WMTA (6.65%) the highest, with no statistically significant difference (P > .05). The release of several chemical elements was observed, mostly metal ions. Only GMTA and EB + Bi2O3 showed the presence of Cr, with significant difference (P < .05). EB + ZnO presented the highest levels of Pb, followed by WMTA (P < .05). For As, the cements presented different release levels, with EB + ZnO showing the highest and GMTA the lowest levels (P < .05). However, the amounts of As and Pb released were lower than the safe limit proposed by ISO 9917-1.<br /><br /><strong>CONCLUSIONS: </strong>Irrespective of the radiopacifying agents used, EndoBinder presented similar behavior to MTA.",
Arsenic,1337333,"Sodium arsenite induced cardiotoxicity in rats: Protective role of p-coumaric acid, a common dietary polyphenol Abstract: This study was performed to investigate the ameliorative role of p-coumaric acid against sodium arsenite-induced cardiotoxicity in rats. Sodium arsenite (5?mg/kg/b.wt) was orally administered once a day for 30 days to the animals to induce cardiotoxicity. After the experimental period, cardiotoxicity was assessed by estimating the levels of lipid peroxidation, anti-oxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, total reduced glutathione, protein sulfyhydryl and non-protein sulfhydryl groups) and DNA fragmentation in the cardiac tissue of control and experimental rats. In addition, cardiac tissue specific serum markers (triacylglycerides, total cholesterol, low-density lipoprotein cholesterol and high density lipoprotein cholesterol) in serum and histopathological changes in the cardiac tissue were also evaluated. From the results obtained in our study, sodium arsenite administration to the rats increased lipid peroxidation, DNA fragmentation, triacylglycerides, total cholesterol and low-density lipoprotein cholesterol, whereas antioxidant status and high-density lipoprotein cholesterol were found to be reduced. However, p-coumaric acid (75 and100?mg/kg/b.wt) treatment orally once per day for 30 days, immediately before a daily administration of sodium arsenite protected the abnormal biochemical abnormalities observed in the cardiac tissue of sodium arsenite treated rats as evidenced by the cardiac histopathology. For comparison purpose, a standard antioxidant vitamin C (100?mg/kg/b.wt) was used. In conclusion, this study concluded that p-coumaric acid could be a promising candidate for protecting the sodium arsenite-induced cardiotoxicity in rats through its antioxidant character.",
Arsenic,94738,"Effects of chronic arsenic exposure on hematopoietic function in adult mammalian liver Abstract: In these studies the effects of ingested arsenic (As(+5)) on hepatic heme biosynthetic capability and hemoprotein function in adult male rats were investigated. Animals exposed for 6 weeks to 0, 20, 40, or 85 ppm sodium arsenate in the drinking water suffered depression of hepatic delta-aminolevulinic acid (ALA) synthetase and heme synthetase (ferrochelatase) activities, with maximal decreases to 67 and 55% of control levels, respectively, at 85 ppm. Concomitantly, urinary uroporphyrin levels were elevated by as much as 12 times, and coproporphyrin by as much as 9 times, control values. The rate of incorporation of (3)H-ALA into mitochondrial and microsomal hemes was depressed by 40-50% at 20 ppm but was increased with regard to controls by as much as 150% at the higher treatment levels. A similar biphasic pattern was observed in regard to (14)C-leucine incorporation into cellular membranal proteins. In contrast, the levels of ALA dehydratase, uroporphyrinogen I synthetase, aminopyrine demethylase, and cytochrome P-450 were not significantly changed in As(+5)-treated rats. These results support the hypothesis that chronic, low level, arsenic exposure results in selective inhibition of mitochondrial-bound heme biosynthetic pathway enzymes (ALA synthetase and heme synthetase) resulting in a substantial increase in urinary porphyrins, uniquely characterized by a greater increase in uroporphyrin than coproporphyrin levels. These changes occur independent of, or prior to, alterations in hepatic hemoprotein-dependent functions and may thus serve in the clinical analysis of pretoxic exposure to arsenic compounds in human populations.",
Arsenic,1704063,"Investigation of Arsenic Airborne in Particulate Matter around Caterers' Wood Fires in the Cape Town Region Abstract: Smoke from wood fires has long been recognized as a significant health hazard. Our recent work has reported on the occurrence of waste timber previously treated by chromated copper arsenate (CCA) insecticide in the fuel supplies of informally operating caterers in the Cape Town region. The main objective of this paper is to report evidence that the burning of CCA-treated wood by informal caterers does lead to arsenic enrichment of the smoke. Atmospheric particulate matter with aerodynamic diameter <= 10 mu m (PM10) was collected using an Air Metrics MiniVol portable aerosol sampler onto quartz filters for durations varying from 1 h to 4 h, at 5 L/min. Smoke was first sampled under controlled conditions, in which CCA-treated samples (of hazard classes H5 and H2) and two untreated wood samples were burned. 18 field samples were collected, from Nyanga, Langa and Khayelitsha (Cape Town) and Kayamandi (Stellenbosch). The PM10 concentrations were calculated and the smoke samples were microwave-digested using nitric acid for metals analysis by ICP-AES. Under controlled conditions, the concentrations of arsenic volatilised from (H2 and H5) were 19 and 52 mu g/m(3), and the As:Cu and As:Cr ratios strongly increased compared the ratios found in the timber. The lowest concentration of PM10 was found around the Nyanga taxi rank at a distance of +/- 100 m from caterers, at 33 mu g/m(3) , while the highest concentration was 8139 mu g/m(3) for a 1-hour sample representing occupational exposure close to wood burning fires. Arsenic was detected in 15 smoke samples. The average arsenic level of positive samples was 1.3 mu g/m(3). The arsenic levels measured exceed normal background levels, which have been reported by the WHO to be 0.02-4 ng/m(3) in rural air and up to 30 ng/m(3) in urban air.",
Arsenic,2343506,"Energy-dispersive X-ray fluorescence analysis of moss and soil from abandoned mining of Pb-Zn ores Abstract: This research investigates heavy metal pollution around one of the most important mining areas in Turkey, the Sebinkarahisar (Giresun) lead-zinc mining, by means of analyzing moss and soil samples collected in the neighborhood of the copper mining at different distances. Energy dispersive X-ray fluorescence spectrometry (Epsilon 5, PANalytical, Almelo, The Netherlands) is utilized in the experiments. The results have indicated that the both moss and soil samples contain aluminum, vanadium, chromium, manganese, iron, nickel, copper, zinc, arsenic, barium, cerium, tungsten, and lead. The comparison of the heavy metal concentrations with the typical measurements in the world and with the limit values for the human health has revealed the critical heavy metal pollution levels in the region. The possible consequences of these results are briefly discussed from the point of potential hazards to ecology and human health.",
Arsenic,1379245,"Complex effects of phenylarsine oxide in T cells. Induction of tyrosine phosphorylation and calcium mobilization independent of CD45 expression Abstract: The effects of phenylarsine oxide, a phosphotyrosine phosphatase inhibitor, on early signal transduction events in human T cells were studied. Simultaneous stimulation of T cells with anti-CD3 monoclonal antibody and phenylarsine oxide prevented increased tyrosine phosphorylation of phospholipase C gamma 1. In contrast, treatment of resting T cells with phenylarsine oxide alone resulted in increased tyrosine phosphorylation of a number of other intracellular substrates. Further, phenylarsine oxide was able to cause an immediate disruption of signal transduction in T cells after anti-CD3 stimulation, as measured by a return of intracellular calcium concentration and inositol 1,4,5-trisphosphate production to base-line levels. Surprisingly, in view of the inhibitory effects of phenylarsine oxide on T cell receptor signal transduction, treatment of T cells with phenylarsine oxide alone caused a dose-dependent increase in intracellular-free calcium concentration that was not accompanied with detectable increases in inositol 1,4,5-trisphosphate production. The phenylarsine oxide-induced increase in free calcium had distinct kinetics from antigen receptor-activated calcium mobilization and was derived from both intracellular sources and increased plasma membrane calcium permeability. This effect was independent of the CD45 transmembrane tyrosine phosphatase. Phenylarsine oxide thus has complex effects on signal transduction in T cells that suggests multiple intracellular targets, and these should be considered in the interpretation of experiments using this agent to study cellular kinase and phosphatase interactions. Finally, the effects of phenylarsine oxide on cellular calcium homeostasis may provide a mechanism of action for the therapeutic and/or toxic effects of arsenicals used for various forms of chemotherapy.",
Arsenic,627248,"Cytogenetic effects in human exposure to arsenic Abstract: The cytogenetic effects of arsenic exposure were studied among rural populations that live in the same geographical area and have similar socioeconomic status, but different degree of exposure to inorganic arsenic (As) via drinking water. A group of inhabitants of Santa Ana (408.17 micrograms/l of As in drinking water) were considered the exposed individuals and a group of inhabitants of Nazareno (29.88 micrograms/l) were considered as controls. Blood and urine samples were obtained from volunteers. Past and current exposure, health, and nutritional status as well as the presence of arsenic skin lesions were ascertained in study participants through questionnaires and physical examination. The frequencies and types of chromosomal aberrations in first-division metaphases were studied in whole blood lymphocyte cultures while the presence of micronuclei (MN) was studied in exfoliated epithelial cells obtained from the oral mucosa and from urine samples. Total arsenic (TAs) content, and the relative proportions of inorganic arsenic (IAs), and the metabolites monomethylarsonic (MMA) and dimethylarsinic (DMA) acid were determined in urine samples. Exposed individuals showed a significant increase in the frequency of chromatid and isochromatid deletions in lymphocytes and of MN in oral and urinary epithelial cells. Males were more affected than females, and a higher number of micronucleated oral cells were found among those individuals with skin lesions. The type of cytogenetic damage observed gives evidence of arsenic as a clastogenic/aneugenic carcinogen.",
Arsenic,25940,"Arsenic in drinking water and the prevalence of respiratory effects in West Bengal, India Abstract: Background - A large population in West Bengal, India has been exposed to naturally occurring inorganic arsenic through their drinking water. A cross-sectional survey involving 7683 participants of all ages was conducted in an arsenic-affected region between April 1995 and March 1996. The main focus of the study was skin keratoses and pigmentation alterations, two characteristic signs of ingested inorganic arsenic. Strong exposure-response gradients were found for these skin lesions. The study also collected limited information concerning respiratory system signs and symptoms, which we report here because increasing evidence suggests that arsenic ingestion also causes pulmonary effects. Methods - Participants were clinically examined and interviewed, and the arsenic content in their current primary drinking water source was measured. There were few smokers and analyses were confined to non-smokers (N = 6864 participants). Results - Among both males and females, the prevalence of cough, shortness of breath, and chest sounds (crepitations and/or rhonchi) in the lungs rose with increasing arsenic concentrations in drinking water. These respiratory effects were most pronounced in individuals with high arsenic water concentrations who also had skin lesions. Prevalence odds ratio (POR) estimates were markedly increased for participants with arsenic-induced skin lesions who also had high levels of arsenic in their current drinking water source (<500 Ág/l) compared with individuals who had normal skin and were exposed to low levels of arsenic (<50 Ág/l). In participants with skin lesions, the age-adjusted POR estimates for cough were 7.8 for females (95% CI: 3.1-19.5) and 5.0 for males (95% CI: 2.6-9.9); for chest sounds POR for females was 9.6 (95% CI: 4.0-22.9) and for males 6.9 (95% CI: 3.1-15.0). The POR for shortness of breath in females was 23.2 (95% CI: 5.8-92.8) and in males 3.7 (95% CI: 1.3-10.6). Conclusion - These results add to evidence that long-term ingestion of inorganic arsenic can cause respiratory effects.",
Arsenic,656944,"Induction of centrosome amplification during arsenite-induced mitotic arrest in CGL-2 cells Abstract: Arsenite-induced mitotic abnormalities result in mitotic death in several cancer cell lines. However, how arsenite induces these effects is not known. We have previously shown that arsenite induces mitotic arrest, mitotic abnormalities, and mitotic death in CGL-2 cells. To further delineate the mechanism of action of arsenite, we examined its effect on centrosome duplication and the possible link between centrosome dysregulation and arsenite-induced mitotic death. Immunofluorescence staining of gamma-tubulin revealed that centrosome amplification was induced in arsenite-arrested mitotic cells but not in nocodazole-arrested cells. When S phase-enriched cells were treated with arsenite, they progressed into and arrested at mitosis and then formed supernumerary centrosomes. A further increase in arsenite-induced centrosome amplification was seen during the prolonged mitotic arrest. The arsenite-induced supernumerary centrosomes might result from uneven fragmentation of centrosome, overexpression of pericentriolar materials, and inhibition of centrosomal coalescence during mitosis. Furthermore, termination of mitotic arrest by treatment of arsenite-arrested mitotic cells with cyclin-dependent kinase 1 inhibitors or by suppression of spindle checkpoint function by small interfering RNA-mediated silencing of BubR1 or Mad2 markedly reduced the induction of centrosome amplification and mitotic death in arsenite-treated cells. These results indicate that centrosome amplification is induced in arsenite-arrested mitotic CGL-2 cells in a spindle checkpoint-dependent manner and is involved in the induction of arsenite-induced mitotic death.",
Arsenic,1371429,DISTRIBUTION AND EXCRETION OF ARSENIC-74 AND SELENIUM-75 IN RATS AFTER THEIR SIMULTANEOUS ADMINISTRATION THE EFFECT OF ARSENIC SELENIUM AND COMBINED PRETREATMENT Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RADIONUCLIDES HEPATIC CLEARANCE ENVIRONMENTAL HUMAN EXPOSURE ANIMAL MODEL,
Arsenic,2064298,"Distribution and accumulation of elements (As, Cu, Fe, Hg, Mn, and Zn) in tissues of fish species from different trophic levels in the Danube River at the confluence with the Sava River (Serbia) Abstract: Pikeperch (Sander lucioperca), European catfish (Silurus glanis), common carp (Cyprinus carpio), and gobies (Neogobius gymnotrachelus, Neogobius melanostomus) were collected from the Danube River (Belgrade section), and samples of liver, muscle, or whole-body composites (in the case of gobies) were analyzed for As, Cu, Fe, Hg, Mn, and Zn with inductively coupled plasma optical spectrometry to find out if there was a correlation between accumulation of these elements in predatory and prey species, as well as in pairs of species with overlapping diets. Concentrations of all analyzed elements were either higher (Cu, Fe, Mn, Zn) in liver than in muscle, or equal (As, Hg), except for Hg in carp, which was higher in muscle. Mercury concentration in liver and muscle of predators (catfish, pikeperch) was significantly (&lt;10(-4)) higher than in prey fishes (carp and gobies). The results indicate that Hg concentration was biomagnified through the food chain. Concentrations of As, Fe, and Hg in carp liver and gobies whole-body composite were similar, but carp had significantly (&lt;10(-4)) higher values of Zn and Cu in liver. The regression analysis and trendline equations indicate that the concentrations of all tested elements, except for As in liver, and Mn and Fe in muscle, were similar in predatory fish (pikeperch and catfish), on one hand, and in prey fish (carp and gobies), on the other hand. Distinctly high Zn concentration in carp is very common in this species due to its physiology. Concentrations of Hg and Zn were higher than the maximum acceptable concentration due to the high pollution level in this section of the Danube River, accordingly posing a risk for the human consumption of these fish species.",
Arsenic,2347590,"Fabrication of magnetic porous Fe-Mn binary oxide nanowires with superior capability for removal of As(III) from water Abstract: Magnetic porous Fe-Mn binary oxide nanowires were successfully fabricated to efficient removal of As(III) from water. The adsorption capacity of the porous nanowires for As(III) obviously increased with increasing of manganese oxide in the composite, accompanying decrease of the saturation magnetization of the adsorbents. Magnetic porous Fe-Mn binary oxide nanowires with an initial Fe:Mn molar ratio of 1:3 exhibited the highest absorption capacity for As(III) and enable magnetic separation from water. The maximal adsorption capacity value is 171mgg(-1) at pH 7.0. In the initial pH range from 3 to 9, 200?gL(-1) of As(III) could be easily decreased to below 10?gL(-1) by the magnetic porous Fe-Mn binary oxide nanowires (0.05gL(-1)) within 75min, and the corresponding residual As was completely oxidized to less toxic As(V). The coexisting chloride, nitrate and sulfate had no significant effect on arsenic removal, whereas, phosphate and humic acid reduced the removal of As(III) by competing with arsenic species for adsorption sites. The resulting magnetic porous Fe-Mn binary oxide nanowires could be a promising adsorbent for As(III) removal from water.",
Arsenic,628518,"Endogenous reductants support the catalytic function of recombinant rat cyt19, an arsenic methyltransferase Abstract: The postulated scheme for the metabolism of inorganic As involves alternating steps of oxidative methylation and of reduction of As from the pentavalent to the trivalent oxidation state, producing methylated compounds containing AsIII that are highly reactive and toxic. S-Adenosyl-L-methionine:AsIII methyltransferase purified from rat liver catalyzes production of methyl and dimethyl arsenicals from inorganic As. This protein is encoded by the cyt19 gene orthologous with cyt19 genes in mouse and human. The reductants dithiothreitol or tris(2-carboxylethyl)phosphine support catalysis by recombinant rat cyt19 (rrcyt19). Coupled systems containing an endogenous reductant (thioredoxin/thioredoxin reductase/NADPH, glutaredoxin/glutathione/glutathione reductase/NADPH, or lipoic acid/thioredoxin reductase/NADPH) support inorganic As methylation by rrcyt19. Although glutathione alone does not support rrcyt19's catalytic function, its addition to reaction mixtures containing other reductants increases the rate of As methylation. Aurothioglucose, an inhibitor of thioredoxin reductase, reduces the rate of As methylation by rrcyt19 in thioredoxin-supported reactions. Addition of guinea pig liver cytosol, a poor source of endogenous As methyltransferase activity, to reaction mixtures containing rrcyt19 shows that endogenous reductants in cytosol support the enzyme's activity. Methylated compounds containing either AsIII or AsV are detected in reaction mixtures containing rrcyt19, suggesting that cycling of As between oxidation states is a component of the pathway producing methylated arsenicals. This enzyme may use endogenous reductants to reduce pentavalent arsenicals to trivalency as a prerequisite for utilization as substrates for methylation reactions. Thus, cyt19 appears to possess both AsIII methyltransferase and AsV reductase activities.",
Arsenic,193374,"DNA damage in buccal epithelial cells from individuals chronically exposed to arsenic via drinking water in Inner Mongolia, China Abstract: The purpose of this pilot study was to assess DNA damage in buccal cells from individuals chronically exposed to arsenic via drinking water in Ba Men, Inner Mongolia. Buccal cells were collected from 19 Ba Men residents exposed to arsenic at 527.5 ± 23.7 ?g/L (mean ± SEM) and 13 controls exposed to arsenic at 4.4 ± 1.0 ?g/L. DNA fragmentation by the DNA ladder and TUNEL assay were used to detect DNA damage in buccal cells. In the DNA ladder assay, 89% (17/19) of the arsenic-exposed group showed <100 bp DNA fragments, in contrast to 15% (2/13) of the controls ( p< 0.0001). For the TUNEL assay, the mean frequencies of positive cells were higher in the exposed group (15.1%) than in the controls (2.0%) (p<0.0001). This study showed that high arsenic exposure via drinking water resulted in DNA damage and DNA fragmentation in buccal cells thus may be an appropriate biomarker for assessing chronic effects of arsenic in humans. A study investigating DNA fragmentation from the individuals with low levels of arsenic exposure in this population is in progress.",
Arsenic,2343555,"Arsenic root sequestration by a tropical woody legume as affected by arbuscular mycorrhizal fungi and organic matter: Implications for land reclamation Abstract: The potential use of the arsenic-tolerant woody leguminous species Anadenanthera peregrina (L) Spegazzini for rehabilitating arsenic (As)-contaminated areas was studied. In an As (539.33 mg/kg)-contaminated soil experiment, plants were able to accumulate arsenic in their roots with a low transfer index to the shoot. Inoculation with arbuscular mycorrhizal fungi (AMF) amplified this behavior and improved both biomass production and the phosphorus concentration in the shoot. AMF inoculation not only improved A. peregrina plant growth but also protected the shoot against As toxicity. Aside from the AMF inoculation, the addition of organic matter reduced the soil pH, thus improving the ability of the roots to accumulate arsenic. The majority (81 %) of the variations in As accumulation in A. peregrina roots were explained by the effects of the organic matter and soil pH as well as AMF treatments, as found by a principal component analysis. A. peregrina promoted phytostabilization through As root sequestration. Therefore, A. peregrina plants inoculated with AMF in the presence of organic matter are recommended to rehabilitate degraded areas of soil contaminated with arsenic.",
Arsenic,8395,"Arsenic and respiratory cancer in man: An occupational study Abstract: To clarify the role of arsenic in human carcinogenesis, the mortality experience of 8,047 white male smelter workers exposed to arsenic trioxide during 1938–63 was studied and compared with that of the white male population of the same States. Smelter workers had an excess total mortality, due mainly to malignant neoplasms of the respiratory system and diseases of the heart. The threefold increase in respiratory cancer was analyzed in relation to the length of employment and degree of exposure to arsenic, sulfur dioxide, and other elements in the smelter. The excess of respiratory cancer was as high as eightfold among employees who worked more than 15 years and who were heavily exposed to arsenic; it showed a gradient in proportion to the degree of exposure to arsenic and sulfur dioxide. The findings support the hypothesis that inhaled arsenic is a respiratory carcinogen in man, but an influence of sulfur dioxide or unidentified chemicals, varying concomitantly with arsenic exposure, cannot be discounted.",
Arsenic,1250974,"Design, synthesis and evaluation of 2-(arylsulfonyl)oxiranes as cell permeable covalent inhibitors of protein tyrosine phosphatases Abstract: A structure-based design approach has been applied to develop 2-(arylsulfonyl)oxiranes as potential covalent inhibitors of protein tyrosine phosphatases. A detailed kinetic analysis of inactivation by these covalent inhibitors reveals that this class of compounds inhibits a panel of PTPs in a time- and dose-dependent manner, consistent with the covalent modification of the enzyme active site. An inactivation experiment in presence of sodium arsenate, a known competitive inhibitor of PTP, indicated that these inhibitors were active-site bound. This finding is consistent with the mass spectrometric analysis of the covalently-modified PTP enzyme. Further experiments indicated that these compounds remained inert towards other classes of arylphosphate-hydrolyzing enzymes, and alkaline and acid phosphatases. Cell-based experiments with human A549 lung cancer cell lines indicated that 2-(phenylsulfonyl)oxirane (1) caused increase in intracellular pTyr levels in a dose-dependent manner thereby suggesting its cell permeable nature. Taken together, the newly identified 2-(arylsulfonyl)oxiranyl moiety could serve as a novel chemotype for the development of activity-based probes and therapeutic agents against PTP superfamily of enzymes.",
Arsenic,1355564,"Speciation analysis and characterisation of arsenic in lavers collected from coastal waters of Fujian, south-eastern China Abstract: ",
Arsenic,1371820,ARSENIC INDUCES INTERLEUKIN-8 EXPRESSION IN CULTURED KERATINOCYTES Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN KERATINOCYTE INTEGUMENTARY SYSTEM INTERLEUKIN-8 EXPRESSION ARSENIC CARCINOGENS TUMOR BIOLOGY SODIUM ARSENITE CARCINOGENESIS INTEGUMENTARY SYSTEM,
Arsenic,1519233,Arsenic Release from the Mine Tailings with Bio-oxidation Pretreatment Abstract: ,
Arsenic,180062,"Atmospheric transport of mold spores in clouds of desert dust Abstract: Fungal spores can be transported globally in clouds of desert dust. Many species of fungi (commonly known as molds) and bacteria—including some that are human pathogens—have characteristics suited to long-range atmospheric transport. Dust from the African desert can affect air quality in Africa, Europe, the Middle East, and the Americas. Asian desert dust can affect air quality in Asia, the Arctic, North America, and Europe. Atmospheric exposure to mold-carrying desert dust may affect human health directly through allergic induction of respiratory stress. In addition, mold spores within these dust clouds may seed downwind ecosystems in both outdoor and indoor environments.",
Arsenic,1018563,"Efflux-mediated resistance to arsenicals in arsenic-resistant and -hypersensitive Chinese hamster cells Abstract: Several Chinese hamster V79 cell line variants resistant to arsenite and one arsenite-hypersensitive variant have been isolated. The basis for the variation in arsenite sensitivity was studied by transport experiments using radiolabeled arsenite. Two arsenite-resistant variants (As/R7 and As/R27) exhibited decreased accumulation of arsenite, and the hypersensitive variant (As/S5) exhibited increased arsenite accumulation compared with the parental line. Cells depleted of endogenous energy reserves were loaded with radiolabeled arsenite, and the rate of arsenic efflux was measured. Arsenite-resistant variants exhibited an increased rate of efflux, while the hypersensitive variant exhibited a decreased efflux rate. Efflux was decreased in cells incubated with the protonophore carbonyl cyanide m-chlorophenylhydrazine, demonstrating its energy dependence. Two inhibitors of glutathione S-transferase also decreased arsenite efflux, suggesting the involvement of an arsenite-glutathione complex. However, separation of the products of extrusion and the intracellular arsenic species by paper chromatography followed by autoradiography failed to show the appearance of an arsenite-glutathione complex in either case. Rather, all label in the product of the transport reaction appeared to be arsenite whether cells were loaded with arsenate or arsenite, indicating first that intracellular reduction of As(V) to As(III) had occurred and second that the arsenite was transported as an unconjugated species. All intracellular label was associated with high-molecular-weight material, possibly protein. Our results demonstrate the existence of an energy-dependent arsenical efflux pump in mammalian cells and show that arsenic is extruded as arsenite.",
Arsenic,1026622,"As(III) transcriptionally activates the gadd45a gene via the formation of H2O2 Abstract: Arsenic is a ubiquitous environmental contaminant associated with increased risks of human cancers of the skin, lung, bladder, and prostate. Intriguingly, it is also used to treat certain types of leukemia. It has recently been suggested that these paradoxic effects may be mediated by arsenic's ability to simultaneously activate DNA damage and apoptotic and transformation pathways. Here, we investigate the effects of arsenic exposure on the induction of the growth arrest and DNA damage protein 45 alpha (GADD45 alpha), which is thought to play roles in apoptosis, DNA damage response, and cell cycle arrest. We found that arsenic transcriptionally activates the gadd45 alpha promoter located in a 153-bp region between -234 and -81, relative to the transcriptional start site. In addition, this transcriptional induction was abrogated in the presence of H2O2 scavengers, suggesting a role for H2O2 in the transcriptional control of the gadd45a gene through a Fenton-like free radical mechanism.",
Arsenic,1020230,"Accumulation of arsenic in tissues of iron-deficient rats Abstract: Toxic concentration of arsenic (400 microg/kg body weight/day) was administered orally for 8 weeks to both iron-supplemented and iron-deficient rats. The results showed greater amount of arsenic in both the duodenum and liver of iron-deficient rats, compared to iron-supplemented ones. Duodenum containing high concentration of arsenic in iron-deficient rats showed significant reduction of ferrireductase (the enzyme responsible for the conversion of ferric iron to ferrous one) activity. Our results suggest that anemic rats are more prone to develop arsenic poisoning following chronic ingestion of high content of arsenic.",
Arsenic,1597392,Plain film as a quick investigation tool for acute arsenic poisoning Abstract: ,
Arsenic,627243,"Induction of DNA damage by free radicals generated either by organic or inorganic arsenic (AsIII, MMAIII, and DMAIII) in cultures of B and T lymphocytes Abstract: The aim of this work is based in the premise that inorganic arsenic (AsIII) and trivalentmethylated metabolites monomethylarsonous (MMAIII) and dimethylarsinous (DMAIII) participate in DNA damage through the generation of reactive oxygen species (ROS). We have utilized two lymphoblastic lines, Raji (B cells) and Jurkat (T cells), which were treated with the trivalent arsenic species (dose: 0-100 microM) and analyzed by two assays (comet assay and flow cytometry) in the determination of DNA damage and ROS effects in vivo. The results showed that the damage to the DNA and the generation of ROS are different in both cellular lines with respect to the dose of organic arsenic, and the order of damage is MMAIII>DMAIII>AsIII. This fact suggests that the DMAIII is not always the more cytotoxic intermediary xenobiotic, as has already been reported in another study.",
Arsenic,1343783,"E-cadherin and alpha-catenin expression in normal, hyperplastic and neoplastic endometrium Abstract: The aim of this study was to determine whether modulation of expression of cell adhesion molecules may occur in neoplastic transformation of endometrial epithelium. MATERIALS AND METHODS: E-Cadherin and ?-catenin protein expression were evaluated by immunohistochemistry in 124 biopsies representative of normal, hyperplastic and neoplastic endometrium. RESULTS: In normal endometrium (proliferative, secretive and atrophic endometrium) strong homogeneous, E-cadherin and ?-catenin reactivity was found; 58.3% and 66.6% of biopsies representative of simple hyperplastic endometrium were homogeneously positive for E-cadherin and ?-catenin, respectively, whereas no samples representative of atypical hyperplasia showed evidence of homogeneous E-cadherin or ?-catenin expression. No expression of homogeneous E-cadherin was seen in endometrial adenocarcinomas; ?-catenin homogeneous immunostaining was observed in 2 G1 and 2 G2 out of 22 adenocarcinoma samples (18.2%). A homogeneous co-expression of both molecules was seen only in normal (70%) and simple hyperplastic (46%) endometrium. CONCLUSION: These results suggest that E-cadherin and ?-catenin down-regulation might be associated with neoplastic transformation of endometrial tissues.",
Arsenic,1029627,"The effect of arsenic exposure and the efficacy of DMSA on the proteins and lipids of the gill tissues of Labeo rohita Abstract: Arsenic is a naturally occurring, highly toxic environmental pollutant. Fourier transform infrared (FT-IR) spectroscopy is a non-disturbing technique which provides quantitative information about the molecular composition of biological samples. The aim of this work is to study the compositional and structural changes at the molecular level occurring in gill tissues of Labeo rohita fingerlings due to arsenic exposure for various exposure periods by using FT-IR spectroscopic technique. The results of the present study suggest that arsenic exposure causes significant changes on the major biochemical constituents such as proteins, lipids and nucleic acids in the gill tissues of L. rohita. The changes are more pronounced as the period of exposure is increased. The significant decrease in the intensity and area of the amide I peak and CH(3) asymmetric stretching band suggests an alteration in the protein profile and lipid levels respectively, due to arsenic exposure. The amide A peak shifts suggests a change in the level of protein amide hydrogen bonding due to arsenic exposure. Further, the treatment with meso-2,3-dimercaptosuccinic acid (DMSA) improves the levels of biochemical constituents significantly, which suggest that DMSA treatment reduces the toxic effects and helps the recovery of gill tissues and its return to the level of the control.",
Arsenic,1022291,"Difference in uptake and toxicity of trivalent and pentavalent inorganic arsenic in rat heart microvessel endothelial cells Abstract: Intake of inorganic arsenic is known to cause vascular diseases as well as skin lesions and cancer in humans. We investigated the differences in cytotoxicity, uptake rate of arsenic, and gene expression of antioxidative enzymes between arsenite (As(3+))- and arsenate (As(5+))-exposed rat heart microvessel endothelial cells. As(3+) was more cytotoxic than As(5+), and LC(50) values were calculated to be 36 and 220 micro M, respectively. As(3+) (1-25 micro M) increased mRNA levels of antioxidant enzymes such as heme oxygenase-1 (HO-1), thioredoxin peroxidase 2, NADPH dehydrogenase, and glutathione S-transferase P subunit. HO-1 mRNA levels showed the most remarkable increase in response to As(3+). cDNA microarray analysis indicated that there was no prominent difference in arsenic-induced transcriptional changes between As(3+)- and As(5+)-exposed cells, when the cells were exposed to one-fourth the LC(50) concentration of arsenic (9 and 55 micro M for As(3+) and As(5+), respectively). N-acetyl- l-cysteine (NAC) reduced both the cytotoxicity of inorganic arsenic and the HO-1 mRNA level, and buthionine sulfoximine enhanced cytotoxicity of inorganic arsenic. As(3+) was taken up by the endothelial cells 6-7 times faster than As(5+), and the presence of NAC in the culture medium did not change the uptake rate of As(3+). These results suggest that the effects of NAC on arsenic-induced cytotoxicity and oxidative stress were due to the antioxidative role of non-protein thiols and not to chelation of arsenic in the culture medium. The difference in cellular uptake of arsenic between As(3+) and As(5+) appeared not to be due to the ionic charge on arsenic (at physiological pH, trivalent arsenic is neutral whereas pentavalent arsenic is negatively charged). These results suggest that the higher toxicity of As(3+) compared with that of As(5+) is probably due to the faster uptake of As(3+) by endothelial cells, and inorganic arsenic exerts its toxicity at least in part via intracellular oxidative stress.",
Arsenic,1018778,Arsenic and lipid peroxidation in patients with blackfoot disease Abstract: ,
Arsenic,1033113,"Arsenic levels in fingernails as a biological indicator of exposure to arsenic Abstract: The analysis of urine, blood, and hair has been used previously to monitor occupational exposure to arsenic (As). Although arsenic is normally present in human fingernails (usually as a result of dietary factors), this study evaluated the potential use of levels of arsenic in fingernails as a biological indicator of occupational exposure to this element. Air samples and fingernail clippings were obtained from individuals with no exposure and high, medium, and low exposure. A washing technique, previously developed to remove exogenous arsenic from hair, was modified to wash the fingernail samples collected in this study. It was demonstrated that 98% of exogenous arsenic was removed from these nails. A high correlation coefficient (r = 0.89) was observed in a comparison of the mean air arsenic concentrations of each exposure group with corresponding arsenic levels in fingernails. From the data collected, an equation was derived to estimate the air arsenic exposure level for a worker from the arsenic content of fingernails: air arsenic concentration (micrograms As/m3) = 1.79 x fingernail arsenic level (micrograms As/g nail)-5.9.",
Arsenic,2337151,"Temperature and pH Effects on Adsorption Materials used for Arsenic Removal from Drinking Water Abstract: This study focused on removal of arsenic from drinking water using different media such as bauxite, lime and plastic clay. Media were treated with different temperature and pH to check adsorption capacity changes. According to the results obtained, temperature (30 degrees C and 40 degrees C), pH 9 and 1h retention time has resulted maximum removal of arsenic on the media. The adsorption data was analyzed and it was found to obey Langmuir model with a good value (0.99) of correlation coefficient.",
Arsenic,2343535,"Cadmium uptake, localization and stress-induced morphogenic response in the fern Pteris vittata Abstract: Cadmium uptake, tissue localization and structural changes induced at cellular level are essential to understand Cd tolerance in plants. In this study we have exposed plants of Pteris vittata to different concentrations of CdCl2 (0, 30, 60, 100 mu M) to evaluate the tolerance of the fern to cadmium. Cadmium content determination and its histochemical localization showed that P. vittata not only takes up, but also transports and accumulates cadmium in the aboveground tissues, delocalizing it mainly in the less bioactive tissues of the frond, the trichomes and the scales. Cadmium tolerance in P. vittata was strictly related to morphogenic response induced by the metal itself in the root system. Adaptive response regarded changes of the root apex size, the developmental pattern of root hairs, the differentiation of xylem elements and endodermal suberin lamellae. All the considered parameters suggest that, in our experimental conditions, 60 mu M of Cd may represent the highest concentration that P. vittata can tolerate; indeed this Cd level even improves the absorbance features of the root and allows good transport and accumulation of the metal in the fronds. The results of this study can provide useful information for phytoremediation strategies of soils contaminated by Cd, exploiting the established ability of P. vittata to transport, delocalize in the aboveground biomass and accumulate polluting metals.",
Arsenic,1381421,"Carcinogenic heavy metals, As3+ and Cr6+, increase affinity of nuclear mono-ubiquitinated annexin A1 for DNA containing 8-oxo-guanosine, and promote translesion DNA synthesis Abstract: To elucidate the biological roles of mono-ubiquitinated annexin A1 in nuclei, we investigated the interaction of purified nuclear mono-ubiquitinated annexin A1 with intact and oxidatively damaged DNA. We synthesized the 80mer 5'-GTCCACTATTAAAGAACGTGGACTCCAACGTCAAAGGGCGAAAAACCGTCTATCAGGGCGATGGCCCACTACGTGAACCA-3' (P0G), and four additional 80mers, each with a selected single G in position 14, 30, 37 or 48 replaced by 8-oxo-guanosine (8-oxo-G) to model DNA damaged at a specific site by oxidation. Nuclear mono-ubiquitinated annexin A1 was able to bind oligonucleotides containing 8-oxo-G at specific positions, and able to anneal damaged oligonucleotide DNA to M13mp18 in the presence of Ca(2+) or heavy metals such as As(3+) and Cr(6+). M13mp18/8-oxo-G-oligonucleotide duplexes were unwound by nuclear annexin A1 in the presence of Mg(2+) and ATP. The binding affinity of nuclear annexin A1 for ssDNA was higher for oxidatively damaged oligonucleotides than for the undamaged oligonucleotide P0G, whereas the maximal binding was not significantly changed. The carcinogenic heavy metals, As(3+) and Cr(6+), increased the affinity of mono-ubiquitinated annexin A1 for oxidatively damaged oligonucleotides. Nuclear mono-ubiquitinated annexin A1 stimulated translesion DNA synthesis by Pol ?. Nuclear extracts of L5178Y tk(+/-) lymphoma cells also promoted translesion DNA synthesis in the presence of the heavy metals As(3+) and Cr(6+). This DNA synthesis was inhibited by anti-annexin A1 antibody. These observations do not prove but provide strong evidence for the hypothesis that nuclear mono-ubiquitinated annexin A1 is involved in heavy metal promoted translesion DNA synthesis, thereby exhibiting the capacity to increase the introduction of mutations into DNA.",
Arsenic,1018361,"Reversal of heavy metal resistance in multidrug-resistant human KB carcinoma cells Abstract: Human KB carcinoma C-A120 cells that express multidrug resistance-associated protein (MRP) were cross-resistant to trivalent and pentavalent antimonials and arsenicals. Intracellular glutathione (GSH) content was higher in C-A120 than its parental KB-3-1 cell line. Glutathione-S-transferase (GST) was similar in both cell lines. Depletion of cellular GSH by treatment of the cells with the inhibitor of gamma-glutamylcysteine synthetase (gamma-GCS), buthione sulfoximine (BSO), significantly increased the sensitivity of both KB-3-1 and C-A120 cells to heavy metals. A pyridine analog, PAK-104P, almost completely reversed the resistance to antimonials and arsenicals in C-A120 cells. BSO at 100 microM or PAK-104P at 10 microM enhanced the accumulation of antimony potassium tartrate in C-A120 cells to the level of that in KB-3-1 cells without the agents. PAK-104P inhibited the ATP-dependent efflux of antimony potassium tartrate. These findings suggest that MRP transports antimony conjugated with GSH ATP-dependently outside the cells and PAK-104P inhibits the transporting activity of MRP.",
Arsenic,2149102,"Toxicity of synthetic chelators and metal availability in poultry manure amended Cd, Pb and As contaminated agricultural soil Abstract: Chelating agents added to contaminated soils may increase solubility and phytoextraction efficiency of soil metals. However, they can create negative effects on soil biological quality. A 90-day incubation experiment was conducted to evaluate mixed effects of chelating agents and poultry manure on changes in available Cd, Pb and As, CO2-C efflux, microbial biomass C, dissolved organic C (DOC), and N mineralization in metal-polluted agricultural soil. Application of poultry manure resulted in a considerable increase in soil pH, DOC, CO2-C efflux, net N mineralization, net N nitrification, and microbial biomass C compared to those in unmanured soil. Availability of arsenic increased twice in manure amended soil due to changes in pH and DOC. However, adding poultry manure did not affect the concentrations of available Pb and Cd compared to those in control soil. Chelating agents increased CO2-C efflux, DOC, and metal availability but decreased microbial biomass C and net N mineralization. Maximum decrease in microbial biomass C, net N mineralization, and net N nitrification, was observed in EDTA applied soil possibly due to high metal availability to soil microorganisms. Overall results revealed that the application of synthetic chelators in combination with poultry manure enhances available As and demonstrates better environment for soil biota.",
Arsenic,626961,"Low dose exposure to sodium arsenite synergistically interacts with UV radiation to induce mutations and alter DNA repair in human cells Abstract: Inorganic arsenic is a known human carcinogen, yet its mechanism of action remains poorly understood. Epidemiological data suggest that arsenic exposure interacts with UV radiation exposure to increase the risk of skin cancer. Studies have suggested that arsenic is able to impair DNA repair enzymes and alter the repair of UV-induced DNA damage. Here we have tested the hypothesis that arsenite [As(III)] and UV interact synergistically to enhance mutagenesis. TK6 human lymphoblastoid cells that are functionally heterozygous at the thymidine kinase (TK) locus were pre-exposed to As(III) alone and in combination with UV. Our data suggest that As(III) is mutagenic only at high doses at the TK locus. As(III) enhanced UV mutagenesis in a more than additive fashion. To investigate the mechanism underlying this synergy we assessed the removal of UV-induced dimers in TK6 cells using the T4 endonuclease-incorporated Comet assay. Pre-treatment with As(III) specifically inhibited the repair of UV-induced pyrimidine dimer-related DNA damage. Taken together, these data suggest that pre-treatment of human cells with arsenic impairs the nucleotide excision repair pathway and leads to enhanced UV mutagenesis.",
Arsenic,1344871,Competitive Sorption of Arsenate and Phosphate on Aluminum Mining By-product Abstract: ,
Arsenic,1031778,"Quantitative evaluation of the radon and lung cancer association in a case control study of Chinese tin miners Abstract: Studies of underground miners have consistently shown an increased risk of lung cancer with cumulative exposure to radon-222 and its decay products. Although the deleterious effects of high radon exposure are clear, questions regarding the shape of the exposure-response relationship, and the effects of time factors such as attained age, time since exposure and early age at first exposure, the effect of exposure rate, and the joint association of radon exposure and tobacco use have not yet been fully clarified. This report considers these questions by fitting various models for the relative odds of disease to 74 male lung cancer cases who were diagnosed between 1981 and 1984 and were alive in 1985 and an equal number of controls. All subjects are current or past employees of the Yunnan Tin Corporation, Gejiu City, China, who reside in the local area. Workers were interviewed to obtain information on work history, from which radon exposure in cumulative working level months and arsenic exposure were estimated, and on tobacco use. Results indicate that excess relative risk increases by 1.7% per cumulative working level month [95% confidence interval (0.5, 5.4)]. The linear exposure response relationship significantly declines with year since last radon exposure (P = 0.02). The risk trend also declines with increasing exposure rate (P = 0.001), indicating that long duration of exposure at a low rate may be more deleterious than short duration of exposure at a high rate. A unique aspect of this study population is the very early ages at first radon exposure for many of the workers, about 37% of the radon-exposed workers were first exposed under the age of 13 years. The analysis shows no modification of the radon lung cancer relationship with age at first exposure. These patterns of risk with radon exposure are generally consistent with those reported in the recent National Academy of Sciences' Biological Effects of Ionizing Radiations IV report. The primary method of tobacco consumption in this area of China is by waterpipe. Lung cancer risk increases with pipe-years of use. The joint analysis of tobacco use and radon exposure supports the Biological Effects of Ionizing Radiations IV conclusion that the most likely model is between additive and multiplicative. The variations of the radon lung cancer relationship by years since last exposure and exposure rate are not affected by adjustment for arsenic exposure.",
Arsenic,1597358,"Prolonged environmental exposure of arsenic through drinking water on the risk of hypertension and type 2 diabetes Abstract: Prolonged exposure to inorganic arsenic has been a severe environmental public health issue worldwide in the recent decades. Increasing evidence has suggested a possible role of prolonged arsenic exposure through drinking water in the development of arsenic-induced chronic noncancer diseases, among which hypertension and type 2 diabetes (T2D) are the focus of concern. Although exposure to high levels of arsenic has been reported to be associated with excess risk of hypertension or T2D in a dose-dependent manner, the association has yet to be established, especially low-level exposure. This cross-sectional study was designed to evaluate the potential association between prolonged environmental arsenic exposure through drinking water and the prevalence of hypertension and T2D in Inner Mongolia, China, with emphasis on the assessment of low-level exposure. In this study (a total of 669 men and women), we found that the blood pressure levels were significantly correlated with cumulative arsenic exposure and that the systolic blood pressure of the subjects with arsenic exposure >50 ?g/L was significantly higher than those of the subjects with <10 and 10-50 ?g/L exposure. Significant prevalence of hypertension was found in the subjects of the >50 ?g/L group both before and after adjustment for confounders. In addition, a significant negative relationship was found between urinary arsenic percentage of dimethylated arsenic (DMA%) and the prevalence of hypertension in the >50 ?g/L group. However, low-level arsenic exposure (10-50 ?g/L) was not statistically associated with hypertension. No significant difference of blood glucose was found among the groups with different arsenic exposure levels. No statistical association was found between arsenic exposure and T2D. Our findings suggested that prolonged arsenic exposure might play a role in the development of hypertension; however, only high-level arsenic was associated with the risk of hypertension. Our findings also indicated that lower DMA% might be related with the increased susceptibility of arsenic-induced hypertension.",
Arsenic,711030,"Risk of carotid atherosclerosis is associated with low serum paraoxonase (PON1) activity among arsenic exposed residents in Southwestern Taiwan Abstract: To understand whether human paraoxonase 1 (PON1) would modulate the risk for arsenic-related atherosclerosis, we studied 196 residents from an arseniasis-endemic area in Southwestern Taiwan and 291 age- and sex-matched residents from a nearby control area where arsenic exposure was found low. Carotid atherosclerosis was defined by a carotid artery intima-media wall thickness (IMT) of &gt;1.0 mm. Prevalence of carotid atherosclerosis was increased in the arseniasis-endemic area as compared to the control area after adjustment for conventional risk factors (OR=2.20, p&lt;0.01). The prevalence was positively associated with cumulative arsenic exposure (mg/L-year) in a dose-dependent manner. Multiple logistic regression analysis showed that in the endemic group, low serum PON1 activity was an independent risk factor for atherosclerosis (OR=4.18 low vs. high, p&lt;0.05). For those of low PON1 activity and high cumulative arsenic exposure, the odds ratio for the prevalence of atherosclerosis was further increased up to 5.68 (p&lt;0.05). No significant association was found between atherosclerosis and four polymorphisms of the PON gene cluster (PON1 -108C/T, PON1 Q192R, PON2 A148G, PON2 C311S). However, genetic frequencies of certain alleles including PON1 Q192, PON2 G148 and PON2 C311 were found increased in the endemic group as compared to the controls and a general Chinese population, indicating a possible survival selection in the endemic group after a long arsenic exposure history. Our results showed a significant joint effect between arsenic exposure and serum PON1 activity on carotid atherosclerosis, suggesting that subjects of low PON1 activity may be more susceptible to arsenic-related cardiovascular disease.",
Arsenic,1704096,Potential Risk of Arsenic and Antimony Accumulation by Medicinal Plants Naturally Growing on Old Mining Sites Abstract: ,
Arsenic,627044,"Incidence of transitional cell carcinoma of the bladder and arsenic exposure in New Hampshire Abstract: Arsenic is a known bladder carcinogen and populations exposed to high arsenic levels in their water supply have reported elevated bladder cancer mortality and incidence rates. To examine the effects of lower levels of arsenic exposure on bladder cancer incidence, we conducted a case-control study in New Hampshire, USA where levels above 10 micro/l are commonly found in private wells.<br /><br /> We studied 383 cases of transitional cell carcinoma of the bladder cancer, newly diagnosed between July 1, 1994 and June 30, 1998 and 641 general population controls. Individual exposure to arsenic was determined in toenail clippings using instrumental neutron activation analysis.<br /><br /> Among smokers, an elevated odds ratio (OR) for bladder cancer was observed for the uppermost category of arsenic (OR: 2.17, 95% CI: 0.92-5.11 for greater than 0.330 mcg/g compared to less than 0.06 micro/g). Among never smokers, there was no association between arsenic and bladder cancer risk.<br /><br /> These, and other data, suggest that ingestion of low to moderate arsenic levels may affect bladder cancer incidence, and that cigarette smoking may act as a co-carcinogen.",
Arsenic,1936196,ISOLATION AND FUNCTIONAL CHARACTERISATION OF LEAD-RESISTANT ENTEROBACTER AEROGENES (BDUP1) FROM PAINT INDUSTRY EFFLUENT CONTAMINATED SITE Abstract: ,
Arsenic,628492,"Arsenic and fluoride exposure in drinking water: Children's IQ and growth in Shanyin county, Shanxi province, China Abstract: BACKGROUND: Recently, in a cross-sectional study of 201 children in Araihazar, Bangladesh, exposure to arsenic (As) in drinking water has been shown to lower the scores on tests that measure children's intellectual function before and after adjustment for sociodemographic features. OBJECTIVES: We investigated the effects of As and fluoride exposure on children's intelligence and growth. METHODS: We report the results of a study of 720 children between 8 and 12 years of age in rural villages in Shanyin county, Shanxi province, China. The children were exposed to As at concentrations of 142 +/- 106 microg/L (medium-As group) and 190 +/- 183 microg/L (high-As group) in drinking water compared with the control group that was exposed to low concentrations of As (2 +/- 3 microg/L) and low concentrations of fluoride (0.5 +/- 0.2 mg/L). A study group of children exposed to high concentrations of fluoride (8.3 +/- 1.9 mg/L) but low concentrations of As (3 +/- 3 microg/L) was also included because of the common occurrence of elevated concentrations of fluoride in groundwater in our study area. A standardized IQ (intelligence quotient) test was modified for children in rural China and was based on the classic Raven's test used to determine the effects of these exposures on children's intelligence. A standardized measurement procedure for weight, height, chest circumference, and lung capacity was used to determine the effects of these exposures on children's growth. RESULTS: The mean IQ scores decreased from 105 +/- 15 for the control group, to 101 +/- 16 for the medium-As group (p < 0.05), and to 95 +/- 17 for the high-As group (p < 0.01). The mean IQ score for the high-fluoride group was 101 +/- 16 and significantly different from that of the control group (p < 0.05). Children in the control group were taller than those in the high-fluoride group (p < 0.05); weighed more than the those in the high-As group (p < 0.05); and had higher lung capacity than those in the medium-As group (p < 0.05). CONCLUSIONS: Children's intelligence and growth can be affected by high concentrations of As or fluoride. The IQ scores of the children in the high-As group were the lowest among the four groups we investigated. It is more significant that high concentrations of As affect children's intelligence. It indicates that arsenic exposure can affect children's intelligence and growth.",
Arsenic,1519214,"The protective role of vitamin E on the testicular tissue in rats exposed to sodium arsenite during the prenatal stage till sex maturity: A stereological analysis Abstract: Background: Vitamin E is an effective antioxidant, protecting cells against oxidative stress. Objective: In this investigation the protective effect of vitamin E on the testis during development and spermatogenesis in rats exposed to sodium arsenite was evaluated. Materials and Methods: Pregnant Wistar rats were divided into 4 groups (n=8) control, sodium arsenite (8 mg/kg/day), sodium arsenite+vitamin E (100 mg/kg/day) and vitamin E. Treatment was carried out from day seven of pregnancy till 90 days. Finally the right testis was stereologically studied. The obtained data was analyzed using one way ANOVA and Tukey's test and the means difference was considered significant at p <0.05. Results: The weight and volume of testis, volume of seminiferous tubules and its diameter, volume of interstitial tissue, height of germinal epithelium and the total number of types A and B spermatogonia, spermatocyte, spermatid and sertoli cells reduced significantly in sodium arsenite group compared to the control. Co-administration of vitamin E and sodium arsenite compensated the adverse effects of sodium arsenite on the above parameters. Conclusion: We concluded co-treatment of rats with sodium arsenite and vitamin E could prevent the adverse effects of sodium arsenite exposure on the testicular tissue during the prenatal stage till sex maturity.",
Arsenic,1268201,"Notification of adverse health effects due to chemicals: Two different ways in Germany Abstract: BIOSIS COPYRIGHT: BIOL ABS. The reporting of adverse health effects caused by chemical substances is regulated in Germany by the Ordinance on Industrial Diseases and the Chemical Substances Act. This retrospective analysis is based on the latest available annual reports for the year 1993, published by the Federal Ministry of Labor and Social Order, the Employers' Liability Insurance Associations and the Federal Institute of Consumer Health Protection and Veterinary Medicine. The list of occupational diseases (first published in 1925) currently includes diseases caused by a group of 27 chemicals. In 1993 there were 3,835 (3.5%) reported cases of suspected intoxication. Chemical substances caused 1.5% of all occupational accidents. In addition to this traditional procedure, it has even been necessary for physicians to report intoxications and diseases due to household chemicals and diseases attributed to environmental causes since 1990. Nation-wide 805 cases were registered in 1993. These figures re",
Arsenic,1379852,"Micronucleus Frequency In Blood Lymphocytes From Children Environmentally Exposed To Lead Abstract: Lead has been classified as a possible human carcinogen by the EPA since results from animal models had shown genotoxic effects. However, in adult humans results are controversial and studies to determine genotoxic effects in children environmentally exposed are not available. Thus, we evaluated micronucleus (MN) frequencies in peripheral blood lymphocytes of 47 children from a rural area in a mining zone in Mexico. We used a cross-sectional study design in boys and girls aged 6 to 10 years environmentally exposed to different levels of Pb. Information on sociodemographic status and factors affecting exposure were obtained by parent interviews. Blood lead concentration (PbB) was evaluated using a Zeeman graphite furnace atomic absorption spectrophotometer. Total arsenic (tAs) was determined in urine by hydride generation atomic absorption spectrophotometry as a possible confounding factor. MN were determined in binuclear cultured lymphocytes. Children had PbB values ranging from 2.8 to 20.4 ug/dl (mean of 9.7 ug/dl ?3.8). The average tAs concentration was 15.6 ug/L (ranging from 4.2 to 64.2 ug/L). Four percent of the population had urinary tAs levels above 50 ug/l. MN found in studied children ranged from 0 to 7 MN, within the range of values found in nonexposed children. Preliminary statistical analysis showed no significant correlations between MN frequencies and lead or arsenic levels.",
Arsenic,2345798,"Environmental and health risk assessment of Pb, Zn, As and Sb in soccer field soils and sediments from mine tailings: solid speciation and bioaccessibility Abstract: Areas polluted by the persistent presence of metal(loid)s induce health problems, especially when recreational activities (on land or water) promote human exposure to the pollutants. This study focuses on one of the most encountered worldwide mining waste, i.e. those from the extraction of Pb-Zn-Ag. The representative Pb-Zn-rich tailing (about 64,100 m(3)) sampled is located near a soccer field and a famous river for fishing. The scientific interests is relative to: (1) mobility and bioaccessibility of metal(oid)s, (2) human risk assessments and (3) relationship between human risks and solid-bearing phases in the environment. Soccer field soils, tailings and sediments from the nearby river were sampled; moreover, metal(loid) speciation (from BCR experiments) and bioaccessibility were measured and solid speciation performed by X-ray diffraction and electron microscopy in order to highlight metal(loid) dispersion and impact. Results demonstrate that the soccer field is highly contaminated by Pb, Zn, As and Sb due primarily to waste runoff. In terms of risk assessment, Pb and As human bioaccessibility highlights the major health risk (48 and 22.5 % of human bioaccessibility, respectively). Since local populations are regularly in close contact with metal(loid)s, the health risk due to pollutant exposure needs to be reduced through sustainable waste disposal and the rehabilitation of polluted sites.",
Arsenic,1030128,"Theoretical study of the intake of trace elements (nutrients and contaminants) via total diet in some geographical areas of Spain Abstract: The aim of this study was to monitor exposure to heavy metal contaminants from habitual diets and to estimate the health risk for the consumer by comparing the analyzed content with the acceptable daily intake (ADI). This study is based on the household consumption as assessed by the National Institute of Statistics (INE) and our department. The number of food groups (237) consumed by the population (national and the 17 Autonomy Communities) is considered. A list of the metal content of foods in included. The data were collected from reports issued by the Ministry of Health, other official organizations, and from specialized literature. The results show that the intakes of arsenic (0.019 mg/person/d), mercury (0.004 mg/person/d), and lead (0.082 mg/person/d) do not reach the ADI, but that of cadmium exceeds the ADI in some geographical areas. The intake of zinc and chromium does not exceed the dietetic recommendations.",
Arsenic,1344395,"Mitochondria: The portrayal of an executioner Abstract: Around 2 billion years ago, an alliance between the then ancestral cell of all eukaryotes and an ancestor of today's purple bacteria resulted in a proto-eukaryotic cell, with the new endo-symbiotic bacteria becoming the mitochondria. In years that passed by, mitochondria gradually assumed the central respiratory role playing one of the pivotal regulators in maintaining cellular homeostasis. The complex role of mitochondria in mammalian cell apoptosis came into focus when biochemical studies identified several mitochondrial proteins that are able to activate cellular apoptotic programs directly. Apoptosis or targeted cell destruction is critical both in physiological contexts as well as pathological states. Signals converge on mitochondria to induce mitochondrial membrane permeabilization (MMP). A number of agents such as the Bcl-2 family members (both pro- and anti-apoptotic), calcium and reactive oxygen species can all affect mitochondrial membrane depolarization. Anti-apoptotic Bcl-2 family members (e.g. Bcl-2, Bcl-XL) are normally localized on the mitochondrial membranes while the pro-apoptotic factors such as Bax, Bid, Bad, and Bim translocate to mitochondria in response to apoptotic signals. Bid is cleaved by caspase-8, generating an active truncated-Bid that aids the oligomerization and insertion of Bax into the mitochondrial membrane. Bad is sequestered in the cytoplasm by phosphorylation and is associated with 14-3-3 scaffold protein where its dephosphorylation [i.e. by calcineurin (Cn)] promotes translocation to mitochondria. Bim is localized to microtubules via association with the LC8 dynein light chain, and also translocates to mitochondria following apoptotic stimulus. Several other intracellular signals, including DNA damage and endoplasmic reticulum (ER) stress, also converge on mitochondria to induce MMP, which causes the release of pro-apoptotic factors from the intermembrane space (IMS). Among these, cytochrome c (Cyt c) induces the apoptosis protease-activating factor 1 (APAF-1) and ATP/dATP to assemble the apoptosome, a molecular platform which promotes the proteolytic maturation of the initiator-caspase-9. Active caspase-9, in turn, cleaves and activates the effector caspases, which finally lead to apoptosis. DNA damage may also signal through the activation of caspase-2, which acts upstream mitochondria to favor MMP. Further, p53, the ""guardian of the genome"" may favor MMP by direct interactions with Bak, Bax, Bcl-2, and Bcl-X-L at the outer mitochondrial membrane (OM). With the gaining importance of MMP, an increasing number of experimental anticancer drugs, including lonidamine, arsenite, betulinic acid, CD437, and several amphipathic peptides, are thus now being targeted towards it. Moreover in our lab, work with the anti-neoplastic, immunotherapeutic and apoptotic glycopeptide T11TS also showed MMP during glioma apoptosis. Bid and p53 acted in synergy to activate Bax thereby bringing about T11TS mediated glioma apoptosis via the release of mitochondrial cytochrome c and subsequent caspase activation. Thus the design of mitochondrion-targeted cytotoxic drugs may constitute a novel strategy for overcoming apoptosis resistance where conventional drugs fail to do so.",
Arsenic,2298683,"Fate of arsenate following arsenite oxidation in agrobacterium tumefaciens GW4 Abstract: The fate of arsenate (As(V) ) generated by microbial arsenite (As(III) ) oxidation is poorly understood. Agrobacterium tumefaciens wild type strain (GW4) was studied to determine how the cell copes with As(V) generated in batch culture. GW4 grown heterotrophically with mannitol used As(III) as a supplemental energy supply as reflected by enhanced growth and increased cellular levels of NADH and ATP. Under low phosphate (Pi) conditions and presence of As(III) oxidation, up to ?50% of the resulting As(V) was taken up and found associated with the periplasm, membrane or cytoplasm fractions of the cells. Arsenic was found associated with proteins and polar lipids, but not in nucleic acids or sugars. Thin layer chromatography and GC-MS analysis suggested the presence of arsenolipids in membranes, presumably as part of the bilayer structure of the cell membrane and replacing Pi under Pi-limiting conditions. The potential role of a Pi binding protein (PstS) for As(V) uptake was assessed with the His-tag purified protein. Intrinsic tryptophan fluorescence spectra analysis suggests that PstS can bind As(V) , but with lower affinity as compared to Pi. In early stationary phase cells, the As(V) :Pi ratio was approximately 4.3 and accompanied by an altered cell ultrastructure.",
Arsenic,1350399,"INDUCTION IN-VITRO OF 72-KD HEAT-SHOCK PROTEIN IN A CONTINUOUS-CULTURE OF RAT-THYROID CELLS, FRTL5 Abstract: In Graves' disease and Hashimoto's thyroiditis, the presence of 72-kD heat shock protein (hsp-72) on thyrocytes has been reported. To clarify the significance of this phenomenon, we induced the antigen in thyroid cell culture in vitro. In the FRTL5 rat cell line, which had been heated at 42.5 degrees C or treated with sodium arsenite, expression of hsp-72 was examined with immunoperoxidase staining and immunoprecipitation of the metabolically labelled protein using a specific MoAb. In the cells cultured either with or without thyrotropin (TSH), heat and chemical stresses reproducibly and dose-dependently induced hsp-72 antigen, whereas unstimulated controls had no significant immunoreactivity. Unlike in Graves' retrocular fibroblasts, hydrogen peroxide was not an effective stress in FRTL5, and the induction was not suppressed by methylmercaptoimmidazole and propylthiouracil, nor enhanced by interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha). These data could not support the hypotheses that suppression of thyroid autoimmunity by thionamides is due to their modulatory action on hsp-72 expression, or that presence of that antigen in the thyroid tissues affected by autoimmunity is secondary to cytokine secretion from infiltrating immunocytes. On the other hand, coculture experiments of stressed FRTL5 cells and syngeneic Fisher rat splenocytes suggest that aberrantly expressed hsp may activate part of the thyroid-infiltrating lymphocytes and thereby aggravate autoimmune processes. The induction and detection systems of hsp-72 using FRTL5 cells would facilitate future studies, possibly utilizing human materials as well, to explore possible relations between stress proteins and thyroid autoimmunity.",
Arsenic,2149133,"Polycyclic Aromatic Hydrocarbons and Metals in Transplanted Lichen (Pseudovernia furfuracea) at Sites Adjacent to a Solid-waste Landfill in Central Italy Abstract: The aim of the study was to evaluate the airborne contamination by polycyclic aromatic hydrocarbons (PAHs) and some heavy metals (arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], nickel [Ni], lead [Pb], and zinc [Zn]) of different pollution scenarios around a solid-waste landfill in central Italy using the lichen Pseudovernia furfuracea as a monitoring tool. For this purpose, eight stations around a landfill characterized by different air pollution sources (industrial, agricultural, residential areas, and roads with different traffic intensities), together with three stations far from the landfill (control areas), were monitored using a set of 22 lichen samples (11 samples analysed for PAHs and metals after 4 months, and 11 samples analysed for metals after 8 months). After 4 months of exposure, the lichen content of all of the analysed elements was greater than that in the pre-exposed lichens. In addition, the Cu and Pb concentration after 8 months was greater than the level after 4 months. The order of metal concentration was Zn &gt; Pb &gt; Cu (or Cu &gt; Pb) &gt; Cr &gt; Ni &gt; As &gt; Cd in all cases. The range of ?11PAHs concentration was 634-1,371 ng/g dw (three to seven times greater than the amount in the pre-exposed lichens). The ?11PAHs were dominated (&gt;70 %) by compounds with three aromatic rings. The comparison of the levels of air pollutants among the monitored stations shows nonrelevant spatial patterns between the landfill stations and the control areas; the levels of PAHs and metals found in the lichen samples around the landfill seemed to be more related to the general diffusion of these pollutants in that area.",
Arsenic,1366373,"Nonmelanoma skin cancer in Japanese residents of Kauai, Hawaii Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN BASAL CELL CARCINOMA SQUAMOUS CELL CARCINOMA UV EXPOSURE ARSENIC EXPOSURE",
Arsenic,2298677,"Chromatographic separation of selenium and arsenic: A potential (72)Se/(72)As generator Abstract: An anion exchange method was developed to separate selenium and arsenic for potential utility in a (72)Se/(72)As generator. The separation of the daughter (72)As from the (72)Se parent is based on the relative acid-base behavior of the two oxo-anions in their highest oxidation states. At pH 1.5, selenate is retained on strongly basic anion exchange resin as HSeO4(-) and SeO4(2-), while neutral arsenic acid, H3AsO4, is eluted.",
Arsenic,2278557,"Decontamination of metals, pentachlorophenol, and polychlorined dibenzo-p-dioxins and dibenzofurans polluted soil in alkaline conditions using an amphoteric biosurfactant Abstract: In this paper, flotation in acidic conditions and alkaline leaching soil washing processes were compared to decontaminate four soils with variable contamination with metals, pentachlorophenol (PCP), and polychlorodibenzo dioxins and furans (PCDD/F). The measured concentrations of the four soils prior treatment were between 50 and 250mg/kg for As, 35 and 220mg/kg for Cr, 80 and 350mg/kg for Cu, and 2.5 and 30mg/kg for PCP. PCDD/F concentrations reached 1394, 1375, 3730, and 6289ng/kg for F1, S1, S2, and S3 soils, respectively. The tests were carried out with masses of 100g of soil (fraction 0-2mm) in a 2L beaker or in a 1L flotation cell. Soil flotation in sulphuric acid for 1h at 60 degrees C with three flotation cycles using the surfactant cocamidopropyl betaine (BW) at 1% allows the solubilization of metals and PCP with average removal yields of 85%, 51%, 90%, and 62% for As, Cr, Cu, and PCP, respectively. The alkaline leaching for 2h at 80 degrees C solubilizes As, Cr, Cu, and PCP with average removal yields of 60%, 32%, 77%, and 87%, respectively. Tests on PCDD/F solubilization with different surfactants were carried out in combination with the alkaline leaching process. PCDD/F removal yields of 25%, 72%, 70%, and 74% for F1, S1, S2, and S3 soils, respectively, were obtained using the optimized conditions.",
Arsenic,1025898,"Environmental arsenic as a disruptor of insulin signaling Abstract: Previous laboratory studies have shown that exposures to inorganic As (iAs) disrupt insulin production or glucose metabolism in cellular and animal models. Epidemiological evidence has also linked chronic human exposures to iAs to an increased risk of diabetes mellitus, a metabolic disease characterized by impaired glucose tolerance and insulin resistance. We have recently shown that arsenite and its methylated metabolites inhibit insulin-stimulated glucose uptake in cultured adipocytes by disrupting insulin-activated signal transduction pathway and preventing insulin-dependent translocation of GLUT4 transporters to the plasma membrane. Here, we present results of follow-up studies using male C57BL/6 mice chronically exposed to arsenite (1 to 50 ppm As) or to its metabolite methylarsonite (0.1 to 5 ppm As) in drinking water for 8 weeks. Results of these studies show that only the exposure to arsenite at the highest level of 50 ppm As produces symptoms attributable to impaired glucose tolerance. Notably, tissue concentrations of iAs and its methylated metabolites in pancreas and in major glucose metabolizing tissues in mice in this exposure group were comparable to the concentrations of total As reported in livers of Bangladeshi residents exposed to much lower concentrations of iAs in drinking water. These results suggest that because mice clear iAs and its metabolites more rapidly than humans, much higher exposure levels may be needed in mouse studies to produce the diabetogenic effects of iAs commonly found in human populations exposed to iAs from environmental sources.",
Arsenic,1292190,"Strong Positive Associations Between Seafood, Vegetables, and Alcohol With Blood Mercury and Urinary Arsenic Levels in the Korean Adult Population Abstract: Blood mercury and urinary arsenic levels are more than fivefold greater in the Korean population compared with those of the United States. This may be related to the foods people consumed. Therefore, we examined the associations between food categories and mercury and arsenic exposure in the Korean adult population. Data regarding nutritional, biochemical, and health-related parameters were obtained from a cross-sectional study, the 2008-2009 Korean National Health and Nutrition Examination Survey (3,404 men and women age ?20 years). The log-transformed blood mercury and urinary arsenic levels were regressed against the frequency tertiles of each food group after covariate adjustment for sex, age, residence area, education level, smoking status, and drinking status using food-frequency data. Blood mercury levels in the high consumption groups compared to the low consumption groups were elevated by about 20 percents with salted fish, shellfish, whitefish, bluefish, and alcohol, and by about 9-14 percents with seaweeds, green vegetables, fruits and tea, whereas rice did not affect blood mercury levels. Urinary arsenic levels were markedly increased with consumption of rice, bluefish, salted fish, shellfish, whitefish, and seaweed, whereas they were moderately increased with consumption of grains, green and white vegetables, fruits, coffee, and alcohol. The remaining food categories tended to lower these levels only minimally. In conclusion, the typical Asian diet, which is high in rice, salted fish, shellfish, vegetables, alcoholic beverages, and tea, may be associated with greater blood mercury and urinary arsenic levels. This study suggests that mercury and arsenic contents should be monitored and controlled in soil and water used for agriculture to decrease health risks from heavy-metal contamination.",
Arsenic,1378228,"Molecular Events During Transplacental Inorganic Arsenic Carcinogenesis In Mice: Aberrant Activation Of Genes Linked To Cell Cycle Dysregulation Abstract: Defining carcinogenic mechanisms is critical to assessing the human health hazard of arsenic exposure. As gestation is a time of high sensitivity to chemical carcinogenesis, we have performed several in utero exposure studies with inorganic arsenic. Pregnant mice received drinking water containing sodium arsenite at various levels, and the offspring were observed for up to 2 years. As adults, male offspring consistently developed hepatocellular carcinoma (HCC) and adrenal tumors, while female offspring showed ovarian and lung tumors, as well as uterine and oviduct preneoplasia. The livers of adult male mice bearing arsenic-induced HCC after in utero exposure showed marked over-expression of estrogen receptor-alpha (ER) at both the protein and RNA levels. ER is an estrogen activated transcription factor mediating cell proliferation. ER was intensely localized within the liver cell nucleus, indicating the active form. Activation of hepatic cyclin D1, which can be turned on by ER, was also seen in arsenic exposed mice. Cyclin D1 is critical in cell cycle regulation and, if over-expressed, is considered a hepatic oncogene. In utero arsenite induced hypomethylation of the ER promoter region DNA, probably accounting for its over-expression. The cyclin D1 promoter was constitutively unmethylated, and unaltered by arsenic exposure, indicating over-expression was a secondary event. As further evidence that ER over-expression had functional impact, a female pattern of metabolic enzymes occurred in adult male liver after in utero arsenic exposure, including over-expression of female-dominant CYP2A4 and CYP2B9, and reduced expression of male-dominant CYP7B1. In summary, altered gene expression occurred in the livers of adult mice bearing HCC induced by in utero arsenite exposure that likely resulted in cell cycle dysregulation and enhanced proliferation. Thus, aberrant estrogen signaling, possibly from methylation errors, may play a role in liver cancers induced by in utero arsenic exposure.",
Arsenic,1353847,"Distribution of As, Cd, Pb, and Zn in redox features of mine-waste impacted wetland soils Abstract: Purpose: Wetland soils of the Coeur d’Alene (CdA) River Basin of northern Idaho, USA are contaminated with toxic elements released during mining activities. In this paper, we report results from a multi-scale investigation of total As, Cd, Pb, and Zn distributions along a transect of these contaminated soils. Materials and methods: Four sites along an 80-m transect were established at the Black Rock Slough wetland in CdA River Basin. The elevation difference between the upslope and lowland site was 1.1 m. Soils were sampled from three depths, down to 45 cm. Redoximorphic features were isolated from the soils and categorized into five types of cemented particles, and Fe-enriched and depleted soil masses. Soils and isolated soil separates were analyzed for total elemental concentration. Results and discussion: Within soil profiles, contaminants are enriched in surface horizons as compared to the original depositional profiles. Enrichment was more dramatic in the upland sites than the lowland sites. Fe-enriched masses that ranged in size from a few millimeters to several centimeters were also enriched in As, Pb, and Zn. At the smallest scale investigated, five different soil aggregate types ranging in size from 1 to 2 mm in diameter had distinct contaminant associations: Fe-cemented aggregates were elevated in As and Zn; Mn-cemented aggregates had more than five times as much Pb as the bulk soil; root channels were elevated in As; and charcoal particles were elevated in all contaminants, particularly Pb and Cd. Conclusions: Results show that in wetland soils pedogenic processes differentially distribute contaminants amongst the redoximorphic features. The distribution is affected by landscape position and water table influence. At the pedon scale, there is an enrichment of As, Cd, Pb, and Zn in surface horizons, suggesting that upward flux of contaminants is occurring. This contaminant redistribution should be considered in design of management and remediation strategies.",
Arsenic,1519077,"Spatial variation of potentially toxic elements in different grain size fractions of marine sediments from Gulf of Mannar, India Abstract: Marine sediments of the Gulf of Mannar (GoM), India are contaminated by potential toxic elements (PTEs) due to anthropogenic activities posing a risk to the existing fragile coral ecosystem and human health. The current study aimed to assess the distribution of PTEs (arsenic-As; cobalt-Co; copper-Cu, molybdenum-Mo; lead-Pb; and zinc-Zn) in marine sediments of different grain size fractions, viz., medium sand (710 ?m), fine sand (250 ?m), and clay (&lt;63 ?m) among the different coastal regions of Pamban, Palk Bay, and Rameswaram coasts of GoM, using grain size as one of the key factor controlling their concentrations. The concentrations of PTEs were measured in the different size fractions of sediment using inductively coupled plasma mass spectrophotometer. The order of accumulation of all PTEs in the three fractions was ranked as Zn &gt; Cu &gt; Pb &gt; As &gt; Co &gt; Mo and in the three locations as Rameswaram &gt; Palk Bay &gt; Pamban. The concentration of PTEs in Palk Bay and Rameswaram coast was significantly different (P?&lt;?0.05), when compared to Pamban coast. Measured geoaccumulation index (I geo) and contamination factor (CF) indicated significant enrichment of Co and Pb from Rameswaram coast when compared to other two coasts. Although the concentration of Co was low but the measured I geo and CF values indicated significant enrichment of this PTE in Rameswaram coast. The increased input of PTEs in the coastal regions of GoM signifies the need to monitor the coast regularly using suitable monitoring tools such as sediments to prevent further damage to the marine ecosystem.",
Arsenic,1029000,Chronic arsenical poisoning due to prolonged administration of a bromide and arsenic mixture Abstract: ,
Arsenic,628804,"Arsenic induced mitochondrial DNA damage and altered mitochondrial oxidative function: Implications for genotoxic mechanisms in mammalian cells Abstract: Arsenic is a well-established human carcinogen that is chronically consumed in drinking water by millions of people worldwide. Recent evidence has suggested that arsenic is a genotoxic carcinogen. Furthermore, we have shown that mitochondria mediate the mutagenic effects of arsenic in mammalian cells, as arsenic did not induce nuclear mutations in mitochondrial DNA (mtDNA)-depleted cells. Using the human-hamster hybrid A(L) cells, we show here that arsenic alters mitochondrial function by decreasing cytochrome c oxidase function and oxygen consumption but increasing citrate synthase function. These alterations correlated with depletion in mtDNA copy number and increase in large heteroplasmic mtDNA deletions. In addition, mtDNA isolated periodically from cultures treated continuously with arsenic did not consistently display the same deletion pattern, indicating that the mitochondrial genome was subjected to repeated and continuous damage. These data support the theory that the mitochondria, and particularly mtDNA, are important targets of the mutagenic effects of arsenic in mammalian cells.",
Arsenic,628406,"Enzymatic methylation of arsenic compounds: VII. Monomethylarsonous acid (MMAIII) is the substrate for MMA methyltransferase of rabbit liver and human hepatocytes Abstract: Inorganic arsenite is methylated by some, but not all, animal species to dimethylarsinic acid (DMA). The monomethyl compound containing arsenic in an oxidation state of +3 has been proposed as an intermediate. Using highly purified arsenic methyltransferase from rabbit liver and the partially purified enzyme from Chang human liver hepatocytes, the activity of methylarsonic acid (MMAV) and methylarsonous acid (MMAIII) as a substrate has been characterized by Michaelis-Menten kinetics. The rabbit liver enzyme has a greater affinity for MMAIII (Km = 0.92 x 10(-5) M) than MMAV (Km = 7.0 x 10(-5) M) since the smaller the Km the greater the affinity. In addition, a dithiol, reduced lipoic acid or dithiothreitol, appears to be more active than GSH in satisfying the thiol requirement of the enzyme. Although investigators have been unable to detect the arsenic methyltransferase in surgically removed human liver, its presence in Chang human hepatocytes now has been established. The Km for MMAIII, 3.04 x 10(-6), using MMAIII methyltransferase from Chang human hepatocytes was not greatly different from that of the rabbit liver enzyme.",
Arsenic,2064193,"Polymorphism of inflammatory genes and arsenic methylation capacity are associated with urothelial carcinoma Abstract: Chronic exposure to arsenic can generate reactive oxidative species, which can induce certain proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-?), interleukin-6 (IL-6) and interleukin-8 (IL-8). TNF-?, IL-6 and IL-8 have been shown to be involved in the development and progression of various cancers, including bladder cancer. This study aimed to investigate the joint effect of the polymorphism of TNF-? -308 G/A, IL-6 -174 G/C, IL-8 -251 T/A and urinary arsenic profiles on urothelial carcinoma (UC) risk. This study evaluated 300 pathologically-confirmed cases of UC and 594 cancer-free controls. Urinary arsenic species were detected using high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. The polymorphism of TNF-? -308 G/A, IL-6 -174 G/C and IL-8 -251 T/A was determined using polymerase chain reaction-restriction fragment length polymorphism. The joint effects on UC risk were estimated by odds ratios and 95% confidence intervals using unconditional logistic regression. We found that the TNF-? -308 A/A and IL-8 -251 T/T polymorphisms were significantly associated with UC. Moreover, significant dose-response joint effect of TNF-? -308 A/A or IL-8 -251 T/T genotypes and arsenic methylation indices were seen to affect UC risk. The present results also showed a significant increase in UC risk in subjects with the IL-8 -251 T/T genotype for each SD increase in urinary total arsenic and MMA%. In contrast, a significant decrease in UC risk was found in subjects who carried the IL-8 -251 T/T genotype for each SD increase in DMA%.",
Arsenic,2337245,"Inverse association between toenail arsenic and body mass index in a population of welders Abstract: Recent data show that arsenic may play a role in obesity-related diseases. However, urinary arsenic studies report an inverse association between arsenic level and body mass index (BMI). We explored whether toenail arsenic, a long-term exposure measure, was associated with BMI in 74 welders with known arsenic exposure. BMI showed significant inverse associations with toenail arsenic (p=0.01), which persisted in models adjusted for demographics, diet and work history. It is unclear whether low arsenic biomarker concentrations in high BMI subjects truly reflect lower exposures, or instead reflect internal or metabolic changes that alter arsenic metabolism and tissue deposition.",
Arsenic,1794808,"Synthesis of mesoporous Cu/Mg/Fe layered double hydroxide and its adsorption performance for arsenate in aqueous solutions Abstract: The mesoporous Cu/Mg/Fe layered double hydroxide (Cu/Mg/Fe-LDH) with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions. The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry, X-ray diffraction crystallography, scanning electron microscopy, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller. Effects of various physico-chemical parameters such as pH, adsorbent dosage, contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated. Results showed that it was efficient for the removal of arsenate, and the removal efficiency of arsenate increased with the increment of the adsorbent dosage, while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11. The adsorption isotherms can be well described by the Langmuir model with R2 &gt; 0.99. Its adsorption kinetics followed the pseudo second-order kinetic model. Coexisting ions such as HPO4(2-), CO3(2-), SO4(2-) and NO3(-) could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH. The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process. It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of &lt; 10 microg/L under the experimental conditions, and makes it a potential material for the decontamination of arsenate polluted water.",
Arsenic,1034559,"Outbreak of chronic arsenic poisoning among retired workers from an arsenic mine in Japan Abstract: Retired former workers of Matsuo Arsenic Mine of Miyazaki prefecture in Japan were subjected to extensive medical examination. The number of retired workers subjected to examination were 61 of 208 workers who were engaged in the works of the mine and were tracked down by the work rolls. These workers left the mine more than 15 years prior to the time of the examination. The main works in the mine were classified as mining, dressing of ores, refining, and clerical work. Several findings such as arsenodermatitis, depigmentation, performation of nasal septum, hyposmia, anosmia, and peripheral nervous disturbance attributed to exposure to arsenic were observed in 9 of 21 roasters who often worked in the arsenic kitchen. No characteristic findings of arsenic poisoning, that is, gastrointestinal disturbance, disorder of the cardiovascular system, hematopoietic disorders, or liver disturbance were observed in the retired workers. Another notable finding was that 8 cases diagnosed as pneumoconiosis were found in 18 miners.",
Arsenic,2337073,"Screening of wild plants for use in the phytoremediation of mining-influenced soils containing arsenic in semiarid environments Abstract: When dealing with remediation projects in zones affected by mining activities, the risk posed by the ingestion of the plants by fauna is often forgotten. The purpose of this study is the assessment of arsenic assimilation by the natural vegetation in these areas. To study the transfer to the trophic chain two mammals, the sheep and the vole are selected. The risk analysis is founded on the contribution of these natural plants to the ingestion. <br> <br>Soil samples and the same number of plants (165) growing in the soils were collected in an old mining area in the southeast of Spain. Physico-chemical properties were calculated by means of the usual procedures. To determine the arsenic content, the soil samples and plant materials were digested by means of a microwave system and the arsenic concentration was determined using atomic fluorescence spectrometry with automated continuous flow hydride generation (HG-AFS). A semiquantitative estimation of the mineralogical composition of the samples was made by X-ray diffraction analysis. <br> <br>The mineralogy and As content of the soils studied depends on the materials related with the mining activity. The descriptive statistical analysis of the population of plants studied points to an As range of 0.31-150 mg/kg in roots, although the concentration in shoots was lower (0.21-83.4 mg/kg). Bioconcentration (BCF) and transfer factors (TF) were studied for each plant species and soil type on which it grew. The results show that As transfer depends on the plant species and the characteristics of the soil. The potential risk of As entering the food chain through the plant species was evaluated. The exposure pathway considered was oral ingestion, calculating the contribution of the plant to the daily dose based on the arsenic concentration in the shoots of the plants analysed. <br> <br>In the samples studied, the levels of As in roots were higher than in shoots, and increased with the As concentration in the soil. The BCFs were generally very low, and the TFs while slightly higher, seldom exceeded unity. When undertaking with the phytoremediation of contaminated sites, the contribution of the As level in plants to the daily diet of animals should be used as an indicator for the screening of the vegetal species to be used.",
Arsenic,1509351,"Phylogenetic and genome analyses of antimony-oxidizing bacteria isolated from antimony mined soil Abstract: Antimony-oxidizing bacteria play an important role in the biogeochemical cycling of antimony, converting the more toxic Sb(?) to the less toxic Sb(?). Little is known about the bacterial species and mechanisms involved in mediating Sb(?) oxidation. In this study, 25 Sb(?)-resistant bacteria were isolated from Sb mined soil. Among these strains, 6 were Sb(?)-oxidizing bacteria including Acinetobacter sp. JL7, Comamonas sp. JL25, Comamonas sp. JL40, Comamonas sp. S44, Stenotrophomonas sp. JL9 and Variovorax sp. JL23. Strain S44 showed the highest Sb(?) oxidation rate which could aerobically oxidize 50 ?M Sb(?) to Sb(?) in 3 d. Whole genome sequencing of strain S44 revealed a number of genes encoding putative metal(loid) resistance proteins including 2 putative As(?)/Sb(?) efflux pump proteins ArsB. Based on our study, the ability of Sb(?) resistance and oxidation was found among diverse bacterial lineages. Microbiological oxidation of Sb(?) may therefore be widely distributed across different bacterial lineages mediating detoxification of Sb at high concentrations in the environment.",
Arsenic,1018033,"Alpha-lipoic acid regulates heme oxygenase gene expression and nuclear Nrf2 activation as a mechanism of protection against arsenic exposure in HepG2 cells Abstract: Oxidative stress is a known mechanism induced, among other things, by arsenic toxicity. As a response, the cell triggers the synthesis of antioxidant and stress response elements like glutathione and heme oxygenase. Alpha-lipoic acid (ALA) is a well-known antioxidant that confers protection to oxidative stress conditions. We analyzed the effect of ALA pretreatment on Nrf2-responsive gene expression of HepG2 cells exposed to As(3+). Cells were treated with 5mM ALA and 8h later exposed to 50?M As(3+) for 24h, analyzing MTT-activity, glutathione content, Nrf2 induction and antioxidant gene expression. As(3+) increased glutathione (154%), heme oxygenase, glutamate cystein ligase, modifier subunit and metallothionein (35-fold, 10-fold and 9-fold, respectively). ALA prevented the strong expression of heme oxygenase by As(3+) exposure (from 35- to 5-times of control cells), which correlated with the reduction of Nrf2 observed in As(3+) group. ALA pretreatment can down-modulate the response mediated by Nrf2 and provide protection to As(3+) exposed HepG2 cells.",
Arsenic,2064292,"Use of a dietary exposure system for screening of insecticidal compounds for their toxicity to the planthopper Laodelphax striatellus Abstract: We developed a dietary exposure assay for screening insecticidal compounds for their toxicity and for assessing the side effects of insecticidal proteins produced by genetically engineered plants on the planthopper Laodelphax striatellus Fallén. The fitness bioassay confirmed that the diet adopted fits the requirements to be used in the dietary exposure system. To validate the efficacy of the dietary exposure system, nymphs of L. striatellus were fed diets treated with different concentrations of an inorganic stomach poison, potassium arsenate (PA), or a cysteine protease inhibitor, E-64. The results showed that with increasing concentrations of E-64, the larval development time was prolonged, the adult weight was reduced and the survival rate of L. striatellus was decreased. Similarly the survival rates of L. striatellus consistently decreased with increasing PA content in the diet. The data indicate that the dietary exposure assay is able to detect the effects of insecticidal compounds on L. striatellus. Subsequently, this assay was successfully used for assessing the potential toxicity of Cry2Aa. The results showed that L. striatellus larvae were not negatively affected when fed the artificial diet containing purified Cry2Aa at 300 ?g/g diet.. In the assay, the stability and bioactivity of Cry proteins in the food sources were confirmed by ELISA and sensitive-insect bioassays. These results show that L. striatellus is not sensitive to Cry2Aa. We conclude that the dietary exposure system is valid and useful for assessing the toxicity of insecticidal compounds produced by GE plants on planthoppers. This article is protected by copyright. All rights reserved.",
Arsenic,1031705,Peripheral neuropathy as a sign of systemic disease Abstract: ,
Arsenic,1347167,"Structure analysis of bacterial community and their heavy-metal resistance determinants in the heavy-metal-contaminated soil sample Abstract: In this study we performed the phylogenetic analysis of non-cultivable bacteria from anthropogenically disturbed soil using partial sequences of the 16S rRNA (16S rDNA) and the heavy-metal resistance genes. This soil sample contained high concentrations of nickel (2,109 mg/kg), cobalt (355 mg/kg) and zinc (177 mg/kg), smaller concentrations of iron (35.75 mg/kg) and copper (32.2 mg/kg), and also a trace amount of cadmium (<0.25 mg/kg). The 16S rDNA sequences from a total of 74 bacterial clones were distributed into four broad taxonomic groups, Acidobacteria, Actinobacteria, Bacteroidetes and Gemmatimonadetes, and some of them were unidentified. Comparing our clone sequences with those from the GenBank database, only 9 clones displayed high similarity to known bacteria belongig to actinomycetes; others were identified as uncultured ones. Among clones evidently Actinobacteria predominated. Sixteen clones from soil sample carried only the nccA-like heavy-metal-resistance genes and all sequences showed too low similarity to known proteins encoded by these genes. However, our results suggested that the heavy-metal-contaminated soil is able to present very important reservoir of the new and until now unknown partly bacteria, partly heavy-metal-resistance determinants and their products. Bacteria and nccA-like genes identified in this study could represent the objects of interest as bioremediation agents because they can be potentially used in different transformation and immobilization processes.",
Arsenic,1339210,"Development of an ion chromatography-inductively coupled plasma-mass spectrometry method to determine inorganic arsenic in liver from chickens treated with roxarsone Abstract: Roxarsone, (4-hydroxy-3-nitrophenyl)arsonic acid, is an arsenic-containing compound that has been approved as a feed additive for poultry and swine since the 1940s; however, little information is available regarding residual arsenic species present in edible tissues. We developed a novel method for the extraction and quantification of arsenic species in chicken liver. A strongly basic solution solubilized the liver, and ultrafiltration removed macromolecules and particulate material. Ion chromatography separated the species [arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, (4-hydroxy-3-aminophenyl)arsonic acid, (4-hydroxy-3-acetaminophenyl)arsonic acid, and roxarsone] in the extracts, which were then detected by inductively coupled plasma-mass spectrometry. The extraction oxidized most arsenite to arsenate. For fortification concentrations at 2 ?g kg-1 and above, recoveries ranged from 70 to 120%, with relative standard deviations from 7 to 34%. We detected roxarsone, its 3-amino and 3-acetamido metabolites, inorganic arsenic, and additional unknown arsenic species in livers from roxarsone-treated chickens. Both the originating laboratory and a second laboratory validated the method.",
Arsenic,1349598,Trace elements in vegetables grown in an area exposed to the emissions of geothermal power plants Abstract: ,
Arsenic,1508693,"Water Safety and Inequality in Access to Drinking-water between Rich and Poor Households Abstract: While water and sanitation are now recognized as a human right by the United Nations, monitoring inequality in safe water access poses challenges. This study uses survey data to calculate household socio-economic-status (SES) indices in seven countries where national drinking-water quality surveys are available. These are used to assess inequalities in access as indicated by type of improved water source, use of safe water, and a combination of these. In Bangladesh, arsenic exposure through drinking-water is not significantly related to SES (p = 0.06) among households using tubewells, whereas in Peru, chlorine residual in piped systems varies significantly with SES (p &lt; 0.0001). In Ethiopia, Nicaragua, and Nigeria, many poor households access nonpiped improved sources, which may provide unsafe water, resulting in greater inequality of access to &quot;safe&quot; water compared to &quot;improved&quot; water sources. Concentration indices increased from 0.08 to 0.15, 0.10 to 0.14, and 0.24 to 0.26, respectively, in these countries. There was minimal difference in Jordan and Tajikistan. Although the results are likely to be underestimates as they exclude individual-level inequalities, they show that use of a binary &quot;improved&quot;/&quot;unimproved&quot; categorization masks substantial inequalities. Future international monitoring programmes should take account of inequality in access and safety.",
Arsenic,62180,"Effects and dose-response relationships of skin cancer and Blackfoot disease with arsenic Abstract: In a limited area on the southwest coast of Taiwan, where artesian well water with a high concentration of arsenic has been used for more than 60 years, a high prevalence of chronic arsenicism has been observed in recent years. The total population of this “endemic” area is approximately 100,000. A general survey of 40,421 inhabitants and follow-up of 1,108 patients with blackfoot disease were made. Blackfoot disease, so-termed locally, is a peripheral vascular disorder resulting in gangrene of the extremities, especially the feet. The overall prevalence rates for skin cancer was 10.6 per 1000, and for blackfoot disease 8.9 per 1000. Generally speaking, the prevalence increased steadily with age in both diseases. The prevalence rates for skin cancer and blackfoot disease increased with the arsenic content of well water, i.e., the higher the arsenic content, the more patients with skin cancer and blackfoot disease. A dose–response relationship between blackfoot disease and the duration of water intake was also noted. Furthermore, the degree of permanent impairment of function in the patient was directly related to duration of intake of arsenical water and to duration of such intake at the time of onset. The most common cause of death in the patients with skin cancer and blackfoot disease was carcinoma of various sites. The 5-year survival rate after the onset of blackfoot disease was 76.3%; the 10-year survival rate was 63.3% and 15-year survival rate, 52.2%. The 50% survival point was 16 years after onset of the disease.",
Arsenic,2337090,"A role for TRAIL/TRAIL-R2 in radiation-induced apoptosis and radiation-induced bystander response of human neural stem cells Abstract: Adult neurons, which are terminally differentiated cells, demonstrate substantial radioresistance. In contrast, human neural stem cells (NSC), which have a significant proliferative capacity, are highly sensitive to ionizing radiation. Cranial irradiation that is widely used for treatment of brain tumors may induce death of NSC and further cause substantial cognitive deficits such as impairing learning and memory. The main goal of our study was to determine a mechanism of NSC radiosensitivity. We observed a constitutive high-level expression of TRAIL-R2 in human NSC. On the other hand, ionizing radiation through generation of reactive oxygen species targeted cell signaling pathways and dramatically changed the pattern of gene expression, including upregulation of TRAIL. A significant increase of endogenous expression and secretion of TRAIL could induce autocrine/paracrine stimulation of the TRAIL-R2-mediated signaling cascade with activation of caspase-3-driven apoptosis. Furthermore, paracrine stimulation could initiate bystander response of non-targeted NSC that is driven by death ligands produced by directly irradiated NSC. Experiments with media transfer from directly irradiated NSC to non-targeted (bystander) NSC confirmed a role of secreted TRAIL for induction of a death signaling cascade in non-targeted NSC. Subsequently, TRAIL production through elimination of bystander TRAIL-R-positive NSC might substantially restrict a final yield of differentiating young neurons. Radiation-induced TRAIL-mediated apoptosis could be partially suppressed by anti-TRAIL antibody added to the cell media. Interestingly, direct gamma-irradiation of SK-N-SH human neuroblastoma cells using clinical doses (2-5 Gy) resulted in low levels of apoptosis in cancer cells that was accompanied however by induction of a strong bystander response in non-targeted NSC. Numerous protective mechanisms were involved in the maintenance of radioresistance of neuroblastoma cells, including constitutive PI3K-AKT over-activation and endogenous synthesis of TGF beta 1. Specific blockage of these survival pathways was accompanied by a dramatic increase in radiosensitivity of neuroblastoma cells. Intercellular communication between cancer cells and NSC could potentially be involved in amplification of cancer pathology in the brain.",
Arsenic,1344426,"Depletion of phospholipid hydroperoxide glutathione peroxidase up-regulates arachidonate metabolism by 12(S)-lipoxygenase and cyclooxygenase 1 in human epidermoid carcinoma A431 cells Abstract: Phospholipid hydroperoxide glutathione peroxidase (PHGPx), a selenium-dependent glutathione peroxidase, can interact with lipophilic substrates, including the phospholipid hydroperoxides, fatty-acid hydroperoxides, and cholesteryl ester hydroperoxides, and reduce them to hydroxide compounds. We studied the functional role of endogenous PHGPx in regulation of 12(S)-lipoxygenase and cyclooxygenase 1 activities in human epidermoid carcinoma A431 cells by using a cell system overexpressing anti-PHGPx mRNA. A retroviral expression vector designated as L1-3, wherein cDNA of PHGPx was reversely inserted into pFB-ERV in antisense orientation, was constructed. A number of stable transfectants of A431 cells with PHGPx depletion were generated from virions containing plasmid L1-3. In an intact cell assay system, the metabolism of arachidonic acid to prostaglandin E2 and 12(S)-hydroxyeicosatetraenoic acid was significantly enhanced in stable L1-3 transfectants compared with that in vector-control cells. Flow cytometric analysis revealed a significant elevated level of intracellular hydroperoxides in stable L1-3 transfectants. Treatment of stable L1-3 transfectants with 50 microM arsenite induced more significant formation of intracellular hydroperoxides than that of vector-control cells. Taken together, these results support the notion that the endogenous PHGPx plays a pivotal role in the regulation of 12(S)-lipoxygenase and cyclooxygenase 1 activities by reducing the level of intracellular lipid hydroperoxides in arachidonate metabolism in A431 cells.",
Arsenic,1246954,From Figures to Values: The Implicit Ethical Judgements in our Measures of Health Abstract: ,
Arsenic,2347605,"Arbuscular mycorrhizal symbiosis influences arsenic accumulation and speciation in Medicago truncatula L. in arsenic-contaminated soil Abstract: In two pot experiments, wild type and a non-mycorrhizal mutant (TR25:3-1) of Medicago truncatula were grown in arsenic (As)-contaminated soil to investigate the influences of arbuscular mycorrhizal fungi (AMF) on As accumulation and speciation in host plants. The results indicated that the plant biomass of M. truncatula was dramatically increased by AM symbiosis. Mycorrhizal colonization significantly increased phosphorus concentrations and decreased As concentrations in plants. Moreover, mycorrhizal colonization generally increased the percentage of arsenite in total As both in shoots and roots, while dimethylarsenic acid (DMA) was only detected in shoots of mycorrhizal plants. The results suggested that AMF are most likely to get involved in the methylating of inorganic As into less toxic organic DMA and also in the reduction of arsenate to arsenite. The study allowed a deeper insight into the As detoxification mechanisms in AM associations. By using the mutant M. truncatula, we demonstrated the importance of AMF in plant As tolerance under natural conditions.",
Arsenic,2278401,"Factors affecting compliance in the first year of postcolposcopy surveillance among women with a high incidence of cervical cancer Abstract: <strong>OBJECTIVE: </strong>To assess postcolposcopy compliance among women with abnormal cervical screening results and to identify factors associated with noncompliance for postcolposcopy follow-up.<br /><br /><strong>METHODS: </strong>In a retrospective study, the records of women who underwent colposcopy at Srinagarind Hospital, Thailand, between January and December 2010 were reviewed. Women were considered to be noncompliant if their total follow-up time after colposcopy was less than 12months. Univariate and multivariate logistic regression methods were used to determine factors significantly predicting noncompliance.<br /><br /><strong>RESULTS: </strong>Among 548 women who underwent colposcopy, the percentage of noncompliance was 49.5% (95% confidence interval [CI], 45.1%-53.7%). The risk for noncompliance rose significantly among those without intraepithelial lesions (OR, 2.19; 95% CI, 1.53-3.13), younger age (OR, 1.79; 95% CI, 1.19-2.67), and low education level (OR, 1.58; 95% CI, 1.11-2.24). Risk for noncompliance was significantly lower among those with a previous history of abnormal smear (OR, 0.39; 95% CI, 0.24-0.64).<br /><br /><strong>CONCLUSION: </strong>The percentage of noncompliance with postcolposcopy follow-up was high among the study women. The significant independent factors predicting noncompliance were previous history of abnormal smear, severity of cervical histopathology, age, and education level.",
Arsenic,2347571,"Comparison of Pb, Zn, Cd, As, Cr, Mo and Sb adsorption onto natural surface coatings in a stream draining natural As geochemical anomaly Abstract: Natural surface coatings (biofilms) were collected on glass slides in the shallow, arsenic-rich stream and were used to compare biofilm trace element adsorption properties. Biofilm element retention and affinities were element specific indicating different processes control their sequestration. Distribution coefficients (K d values), calculated as the ratio between biofilm and dissolved trace element concentrations, revealed solid phase enrichment that, depending on the trace element, extended from 10(0.18) to 10(3.17). Elements were specifically scavenged by the organic constituents of the biofilm itself (Fe, Pb, Zn, Cr) and associated biominerals of poorly ordered Mn oxide (Cd, As, Mo, Sb). The results provide an evidence for the significant role that microbial activity can play in trace element geochemistry in freshwater environment.",
Arsenic,1016364,"Evaluation of in vitro anti-genotoxic potential of melatonin against arsenic and fluoride in human blood cultures Abstract: Melatonin has been known for its anti-oxidant potential but not much studied for the anti-genotoxic potential. The current study elucidate the role of melatonin against in vitro genotoxicity by arsenic (As) and fluoride (F). Human peripheral blood cultures were exposed to As (1.4 microM) and F (34 microM), alone and in combination, with and without melatonin (0.2 mM). Ethyl methane sulphonate (EMS; 1.9 mM) was selected as the positive control to analyze the genotoxic parameters like sister chromatid exchanges (SCEs), cell cycle proliferative index (CCPI) and primary DNA damage. The frequency of SCE/cell, SCE/chromosome and primary DNA damage reduced significantly (p&lt;0.001) accompanied with a marked increase in CCPI upon addition of melatonin. Similarly marked recovery was attained by melatonin from As and F induced primary DNA damage as studied using comet assay. The results clearly indicate towards the protection of lymphocytes from toxic effects af As and F by melatonin in vitro.",
Arsenic,710879,"Biological effects of inorganic arsenic on primary cultures of rat astrocytes Abstract: It is well established that inorganic arsenic induces neurotoxic effects and neurological defects in humans and laboratory animals. The cellular and molecular mechanisms of its actions, however, remain elusive. Herein we report the effects of arsenite (NaAsO2) on primary cultures of rat astrocytes. Cells underwent induction of heat shock protein 70 only at the highest doses of inorganic arsenic (30 and 60 microM), suggesting a high threshold to respond to stress. We also investigated arsenic genotoxicity with the comet assay. Interestingly, although cells treated with 10 microM arsenite for 24 h maintained >70% viability, with respect to untreated cells, high DNA damage was already observed. Since arsenic is not known to be a direct-acting genotoxic agent, we investigated the possibility that its effects are due, in astrocytes as well, to ROS formation, as already described for other cell types. However, FACS analysis after CM-H2DCFDA staining did not evidence any significant increase of ROS production while, on the contrary, at the highest arsenite concentrations used, ROS production decreased. Concordantly, we found that, if most cells in the culture are still alive (i.e. up to 10 microM arsenite), they show a treatment-dependent increase in the concentration of SOD1. On the other hand, SOD2 concentration did not change. Finally, we found that astrocytes also synthesize PIPPin, an RNA-binding protein, the concentration of which was recently reported to change in response to stress induced by cadmium. Here we also report that, in cells exposed to high doses of arsenite, an anti-PIPPin antibody-positive faster migrating protein appears.",
Arsenic,1579383,"Arsenic removal from groundwater using iron electrocoagulation: Effect of charge dosage rate Abstract: We demonstrate that electrocoagulation (EC) using iron electrodes can reduce arsenic below 10 ?g/L in synthetic Bangladesh groundwater and in real groundwater from Bangladesh and Cambodia, while investigating the effect of operating parameters that are often overlooked, such as charge dosage rate. We measure arsenic removal performance over a larger range of current density than in any other single previous EC study (5000-fold: 0.02 - 100 mA/cm(2)) and over a wide range of charge dosage rates (0.060 - 18 Coulombs/L/min). We find that charge dosage rate has significant effects on both removal capacity (?g-As removed/Coulomb) and treatment time and is the appropriate parameter to maintain performance when scaling to different active areas and volumes. We estimate the operating costs of EC treatment in Bangladesh groundwater to be $0.22/m(3). Waste sludge (? 80 - 120 mg/L), when tested with the Toxic Characteristic Leachate Protocol (TCLP), is characterized as non-hazardous. Although our focus is on developing a practical device, our results suggest that As[III] is mostly oxidized via a chemical pathway and does not rely on processes occurring at the anode.",
Arsenic,1018682,Optical processes related to arsenic vacancies in semi-insulating GaAs studied by positron spectroscopy Abstract: ,
Arsenic,2278517,"Natural wetland emissions of methylated trace elements Abstract: Natural wetlands are well known for their significant methane emissions. However, trace element emissions via biomethylation and subsequent volatilization from pristine wetlands are virtually unstudied, even though wetlands constitute large reservoirs for trace elements. Here we show that the average volatile fluxes of selenium (&lt;0.12??g?m(-2)?day(-1)), sulphur (&lt;37??g?m(-2)?day(-1)) and arsenic (&lt;0.54??g?m(-2)?day(-1)) from a pristine peatland are considerable and consistent over two summers. We compare these fluxes with the total concentrations in the peat and show that selenium is up to 40 times more efficiently volatilized than arsenic, and over 100 times more efficiently volatilized than sulphur. We further show that the volatilization of selenium and arsenic increases with temperature, implying that emissions of these health-relevant trace elements will increase with global warming. We suggest that biomethylation and volatilization in wetlands play a crucial role in the mobilization and global biogeochemical cycling of trace elements.",
Arsenic,1337287,"Hair toxic metal concentrations and autism spectrum disorder severity in young children Abstract: Previous studies have found a higher body-burden of toxic metals, particularly mercury (Hg), among subjects diagnosed with an autism spectrum disorder (ASD) in comparison to neurotypical controls. Moreover, Hg body-burden was associated with ASD severity. This cross-sectional study examined the potential correlation between hair toxic metal concentrations and ASD severity in a prospective cohort of participants diagnosed with moderate to severe ASD. The Institutional Review Board at the University of Texas Southwestern Medical Center at Dallas (Dallas, TX) approved the present study. Qualifying study participants (n = 18) were evaluated for ASD severity using the Childhood Autism Rating Scale (CARS) and quantitatively for arsenic, Hg, cadmium, lead, chromium, cobalt, nickel, aluminum, tin, uranium, and manganese using hair toxic element testing by Doctor's Data (a CLIA-approved laboratory). CARS scoring and hair toxic element testing were blinded to one another. Increasing hair Hg concentrations significantly correlated with increased ASD severity. In contrast, no significant correlations were observed between any other of the hair toxic metals examined and ASD severity. This study helps to provide additional mechanistic support for Hg in the etiology of ASD severity, and is supported by an increasing number of recent critical reviews that provide biological plausibility for the role of Hg exposure in the pathogenesis of ASDs.",
Arsenic,1340130,"Atmospheric deposition studies of heavy metals in Arctic by comparative analysis of lichens and cryoconite Abstract: Lichens and cryoconite (rounded or granular, brownish-black debris occurring in holes on the glacier surface) from Ny-Ålesund were used for understanding the elemental deposition pattern in the area. Lichen samples collected from low-lying coastal region and cryoconite samples from high altitudinal glacier area were processed and analysed for elements such as aluminium (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) through inductively coupled plasma mass spectrometry. Results showed that heavy metals, Al and Fe, are present in high concentration in the cryoconite samples. Al was also present in high amounts in seven of the eight lichen samples studied. The general scheme of elements in the decreasing order of their concentrations for most of the cryoconite samples was Al?&gt;?Fe?&gt;?Mn?&gt;?Zn?&gt;?V?&gt;?Pb?&gt;?Cr?&gt;?Ni?&gt;?Cu?&gt;?Co?&gt;?As?&gt;?Cs?&gt;?Cd while that for the lichen samples was Al?&gt;?Fe?&gt;?Zn?&gt;?Mn?&gt;?Pb?&gt;?Cu?&gt;?Cs?&gt;?Cr?&gt;?Ni?&gt;?V?&gt;?Co?&gt;?As?&gt;?Cd. Similarity in trends in the two sample types confirms that the environment indeed contains these elements in that order of concentration which overtime got accumulated in the samples. Overall comparison showed most elements to be present in high concentrations in the cryoconite samples as compared to the lichen samples. Within the lichens, elemental accumulation data suggests that the low-lying site (L-2) from where Cladonia mediterranea sample was collected was the most polluted accumulating a number of elements at high concentrations. The probable reasons for such deposition patterns in the region could be natural (crustal contribution and sea salt spray) and anthropogenic (local and long-distance transmission of dust particles). In the future, this data can form a baseline for monitoring quantum of atmospheric heavy metal deposition in lichens and cryoconite of Svalbard, Arctic.",
Arsenic,1353020,Column Bioleaching of Arsenic and Heavy Metals from Gold Mine Tailings by Aspergillus fumigatus Abstract: ,
Arsenic,1352559,"Cell-based assay for the detection of chemically induced cellular stress by immortalized untransformed transgenic hepatocytes Abstract: <strong>BACKGROUND: </strong>Primary hepatocytes, one of the most widely used cell types for toxicological studies, have a very limited life span and must be freshly derived from mice or even humans. Attempts to use stable cell lines maintaining the enzymatic pattern of liver cells have been so far unsatisfactory. Stress proteins (heat shock proteins, HSPs) have been proposed as general markers of cellular injury and their use for environmental monitoring has been suggested. The aim of this work is to develop a bi-transgenic hepatocyte cell line in order to evaluate the ability of various organic and inorganic chemicals to induce the expression of the HSP70 driven reporter gene. We previously described transgenic mice (Hsp70/hGH) secreting high levels of human Growth Hormone (hGH) following exposure to toxic compounds in vivo and in vitro in primary cultures derived from different organs. In addition, we also reported another transgenic model (AT/cytoMet) allowing the reproducible immortalization of untransformed hepatocytes retaining in vitro complex liver functions.<br /><br /><strong>RESULTS: </strong>The transgenic mouse line Hsp70/hGH was crossed with the AT/cytoMet transgenic strain permitting the reproducible immortalization of untransformed hepatocytes. From double transgenic animals we derived several stable hepatic cell lines (MMH-GH) which showed a highly-differentiated phenotype as judged from the retention of epithelial cell polarity and the profile of gene expression, including hepatocyte-enriched transcription factors and detoxifying enzymes. In these cell lines, stresses induced by exposure to inorganic [Sodium Arsenite (NaAsO2) and Cadmium Chloride (CdCl2)], and organic [Benzo(a)Pyrene (BaP), PentaChloroPhenol (PCP), TetraChloroHydroQuinone (TCHQ), 1-Chloro-2,4-DiNitro-Benzene (CDNB)] compounds, specifically induced hGH release in the culture medium.<br /><br /><strong>CONCLUSIONS: </strong>MMH-GH, an innovative model to evaluate the toxic potential of chemical and physical xenobiotics, provides a simple biological system that may reduce the need for animal experimentation and/or continuously deriving fresh hepatocytes.",
Arsenic,1327573,"Delay of the Excision of UV Light-induced DNA Adducts is Involved in the Coclastogenicity of UV Light Plus Arsenite Abstract: Chromatid exchanges and chromatid breaks were synergistically increased by a 2-h post-treatment with arsenite (VS treatment) but not with arabinofuranosyl cytosine (VA treatment) of UV-irradiated late-G1 Chinese hamster ovary cells. In order to determine the mechanism of this UV-arsenite coclastogenicity, we have compared the effects of arsenite and arabinofuranosyl cytosine on the generation of DNA strand breaks in UV-irradiated cells by alkaline elution and alkaline sucrose sedimentation. Only very small numbers of DNA breaks were detected immediately after VS treatment, however the breaks in parental strands increased as the cells reached mitosis in drug-free medium, whereas a large number of breaks were detected immediately after VA treatment but the breaks decreased thereafter. By labelling the newly synthesized DNA, we have also shown that the VS-treated cells had more breaks in daughter strands than the VA-treated cells at the time of reaching mitosis. The effect of a 2-h post-treatment with arsenite on the excision of UV-induced DNA adducts was further investigated by using the exponentially growing cells. The results confirmed that very low amount of breaks was detectable immediately after VS treatment, however the amount of breaks increased upon the removal of arsenite. Therefore, the breaks in the daughter strands of VS-treated cells may come from DNA replication using templates containing unexcised adducts, or using broken templates. It is conceivable that gaps in the overlapping regions of parental and daughter strands may result in chromatid breaks and that misreplication, because of unexcised adducts or gaps in the parental strands, may result in chromatid exchanges.",
Arsenic,1338912,"Effects of mineral supplementation on liver cirrhotic/cancer male patients Abstract: The aim of the present study was to compare the levels of essential trace and toxic elements in biological samples (blood and serum) of male liver cirrhotic/cancer patients (n?=?144), of age groups 30-50 years, before and after 60 days treatment with mineral supplementation. For comparison purposes, the same biological samples were also collected from healthy male subjects (n?=?120) of the same age groups. The biological samples were oxidized by 65 % HNO(3)/30 % H(2)O(2) (2:1) in a microwave oven. The digests of all biological samples were analyzed for arsenic (As), cadmium (Cd), selenium (Se), and zinc (Zn) by electrothermal atomic absorption spectrometry. The levels of Se and Zn were lower in liver cirrhotic/cancer patients as compared to healthy individuals (p?&lt;?0.001). The patients with liver cirrhosis/cancer have twofold higher As and Cd levels in biological samples as compared to age-matched referents. Moreover, a negative correlation was observed between essential and toxic elements. The pathogenesis of liver cirrhosis/cancer has been associated with changes in the balance of certain essential trace and toxic elements. The study confirms that oral supplements of Se and Zn produce metabolic effects in patients with liver cirrhosis/cancer. It was observed that the status of essential trace elements, Se and Zn, was improved in biological samples of all patients after 60 days of treatment with mineral supplementation.",
Arsenic,628792,"Prospective protective role of melatonin against arsenic-induced metabolic toxicity in Wistar rats Abstract: Subchronic exposure to arsenic is associated with alteration of glucose homeostasis. Arsenic treatment (as sodium arsenite) of male Wistar rats (weighing 130-150 g) at a dose of 5.55 mg kg(-1) body weight (equivalent to 35% of LD(50)) (i.p.) per day for a period of 30 days produced hypoglycemia, with associated increased urinary excretion of glucose and depletion of liver glycogen and pyruvic acid contents. Mobilization of free amino acids from kidney to liver was facilitated by arsenic treatment. Arsenic exposure significantly decreased the glutamate-pyruvate transaminase activity in kidney. Glucose 6-phosphatase activity in liver tissue was also significantly decreased after arsenic treatment. In addition to these, liver lactate dehydrogenase activity was elevated due to arsenic treatment. Melatonin supplementation (i.p.) at a dose of 10 mg kg(-1) day(-1) for last five days prior to sacrifice reversed most of the above changes caused by arsenic. Melatonin, being a potent free radical scavenger may reduce arsenic-induced free radical production, and thereby, eliminating its toxic effects. So, arsenic-induced hypoglycemia, with associated glycogenolytic as well as glycolytic activities of liver can be partially counteracted by melatonin supplementation. Accordingly, it may be suggested that melatonin can serve as a prospective protective agent against arsenic-induced metabolic toxicity.",
Arsenic,1339975,"A pilot study determining hair arsenic and lead levels in residents of a community established on a former landfill in Puerto Rico Abstract: Arsenic (As) and lead (Pb) were determined in hair of 12 adult women and 27 children living in a soil-metal contaminated community in Puerto Rico. Average concentrations in residential soils ranged from 24 to 109 ?g/g for As and from 42 to 1,585 ?g/g for Pb. For hair-As, about 75% of the samples were below 0.08 ?g/g. Hair-Pb presented levels of health concern, with 10% of the samples above a reference value of 5 ?g/g, indicating significant exposure to Pb. Multivariate analyses revealed that children's Pb hair levels were predicted by age and sex, while consumption of home-grown animals influenced the association with soil-Pb.",
Arsenic,2149138,"Antimicrobial-related Severe Adverse Events during Treatment of Methicillin-Susceptible Staphylococcus aureus Bone and Joint Infection Abstract: Prolonged antimicrobial therapy is recommended in methicillin-susceptible Staphylococcus aureus (MSSA) bone and joint infection (BJI), but its safety and risk factors for severe adverse events (SAE) in clinical practice are unknown. We addressed this question in a retrospective cohort study (2001-2011) analysing antimicrobial-related SAE (defined according to Common Terminology Criteria for Adverse Events) in 200 patients (male 62%; age 60.8 (IQR 45.5-74.2)) with MSSA BJI admitted in a reference regional centre with acute (66%) or chronic arthritis (7.5%), osteomyelitis (9.5%), spondylodiscitis (16%), or orthopaedic device-related infections (67%) received anti-staphylococcal therapy for 26.6 weeks (IQR 16.8-37.8). Thirty-eight SAE occurred in 30 patients (15%) in a delay 34 days (IQR 14.75-60.5), including 10 hematologic reactions, 9 cutaneo-mucosal reactions, 6 acute renal injuries, 4 hypokalaemia, and 4 cholestatic hepatitis. The most frequently implicated antimicrobials were anti-staphylococcal penicillins (ASP) (13 SAE/145 patients), fluoroquinolones (12/187), glycopeptides (9/101), and rifampin (7/107). Kaplan-Meier curves and stepwise binary logistic regression were used to determine risk factors for the occurrence of antimicrobial-related SAE. Only age (OR=1.479 for 10-year increase; 95%CI 1.116-1.960; p=0.006) appeared to be independent risk factors for SAE. In patients receiving ASP or rifampin, daily dose (OR 1.028; 95%CI 1.006-1.051, p=0.014) and obesity (OR 8.991; 95%CI 1.453-55.627; p=0.018) were associated with occurrence of SAE, respectively. The high rate of SAE and their determinants highlighted the importance of the management and follow-up of BJI, with a particular attention to be paid in elderly, especially for ASP dosages, and in rifampin dose adjustment in obese patients.",
Arsenic,899764,"Effects of exogenous glutathione on arsenic burden and NO metabolism in brain of mice exposed to arsenite through drinking water Abstract: Chronic exposure to inorganic arsenic (iAs) is associated with neurotoxicity. Studies to date have disclosed that methylation of ingested iAs is the main metabolic pathway, and it is a process relying on reduced glutathione (GSH). The aim of this study was to explore the effects of exogenous GSH on arsenic burden and metabolism of nitric oxide (NO) in the brain of mice exposed to arsenite via drinking water. Mice were exposed to sodium arsenite through drinking water contaminated with 50 mg/L arsenic for 4 weeks and treated intraperitoneally with saline solution, 200 mg/kg body weight (b.w), 400 mg/kg b.w, or 800 mg/kg b.w GSH, respectively, at the 4th week. Levels of iAs, monomethylarsenic acid, and dimethylarsenic acid (DMAs) in the liver, blood, and brain were determined by method of hydride generation coupled with atomic absorption spectrophotometry. Activities of nitric oxide synthase (NOS) and contents of NO in the brain were determined by colorimetric method. Compared with mice exposed to arsenite alone, administration of GSH increased dose-dependently the primary and secondary methylation ratio in the liver, which caused the decrease in percent iAs and increase in percent DMAs in the liver, as a consequence, resulted in significant decrease in iAs levels in the blood and total arsenic levels in both blood and brain. NOS activities and NO levels in the brain of mice in iAs group were significantly lower than those in control; however, administration of GSH could increase significantly activities of NOS and contents of NO. Findings from this study suggested that exogenous GSH could promote both primary and secondary arsenic methylation capacity in the liver, which might facilitate excretion of arsenicals, and consequently reduce arsenic burden in both blood and brain and furthermore ameliorate the effects of arsenicals on NO metabolism in the brain.",
Arsenic,734893,"Modulatory role of Emblica officinalis fruit extract against arsenic induced oxidative stress in Swiss albino mice Abstract: Arsenic, an important human toxin, is naturally occurring in groundwater and its accumulation in plants and animals have assumed a menacing proportion in a large part of the world, particularly Asia. Epidemiological studies have shown a strong association between chronic arsenic exposure and various adverse health effects, including cardiovascular diseases, neurological defects and cancer of lung, skin, bladder, liver and kidney. The protective role of the fruits of Emblica officinalis (500 mg/kg b.wt.) was studied in adult Swiss albino mice against arsenic induced hepatopathy. Arsenic treated group (NaAsO(2), 4 mg/kg b.wt.) had a significant increase in serum transaminases and lipid peroxidation (LPO) content in liver, whereas significant decrease was recorded in hepatic superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and serum alkaline phosphatase activity. Combined treatment of Emblica and arsenic (pre and post) declined the serum transaminases and LPO content in liver whereas significant increase was noticed in SOD, CAT, GST and serum alkaline phosphatase activities. Liver histopathology showed that Emblica fruit extract had reduced karyolysis, karyorrhexis, necrosis and cytoplasmic vacuolization induced by NaAsO(2) intoxication. Thus it can be concluded that pre- and post-supplementation of E. officinalis fruit extract significantly reduced arsenic induced oxidative stress in liver.",
Arsenic,1597304,"Arsenic induces VL30 retrotransposition: the involvement of oxidative stress and heat-shock protein 70 Abstract: Arsenic is an environmental contaminant with known cytotoxic and carcinogenic properties, but the cellular mechanisms of its action are not fully known. As retrotransposition consists a potent mutagenic factor affecting genome stability, we investigated the effect of arsenic on retrotransposition of an enhanced green fluorescent protein (EGFP)-tagged non-autonomous long terminal repeat (LTR)-retrotransposon viral-like 30 (VL30) in a mouse NIH3T3 cell culture-retrotransposition assay. Flow cytometry analysis of assay cells treated with 2.5-20 µM sodium arsenite revealed induction of retrotransposition events, in a dose- and time-dependent manner, which was further confirmed as genomic integrations by PCR analysis and appearance of EGFP-positive cells by UV microscopy. Specifically, 20 µM sodium arsenite strongly induced the VL30 retrotransposition frequency, which was ~90.000-fold higher than the natural one, and also VL30 RNA expression was ~6.6-fold. Inhibition of the activity of endogenous reverse transcriptases (enRTs) by efavirenz at 15 µM or nevirapine at 375 µM suppressed the arsenite-induced VL30 retrotransposition by 71.16- or 79.88%, respectively. In addition, the antioxidant Nacetyl-cysteine (NAC) reduced the level of arsenite-induced retrotransposition, which correlated with the rescue of arsenite-induced G2/M cell cycle arrest and cell toxicity. Treatment of assay cells ectopically overexpressing the human heat-shock protein 70 (Hsp70) with 15 µM sodium arsenite resulted in an additional ~4.5-fold induction of retrotransposition compared to normal assay cells, while treatment with 20 µM produced a massive cell death. Our results show for the first time that arsenic both as an oxidative and heat-shock mimicking agent is a potent inducer of VL30 retrotransposition in mouse cells. The impact of arsenic-induced retrotransposition, as a cellular response, on contribution to or explanation of the arsenic-associated toxicity and carcinogenicity is discussed.",
Arsenic,1021558,"A possible mechanism for combined arsenic and fluoride induced cellular and DNA damage in mice Abstract: Arsenic and fluoride are major contaminants of drinking water. Mechanisms of toxicity following individual exposure to arsenic or fluoride are well known. However, it is not explicit how combined exposure to arsenic and fluoride leads to cellular and/or DNA damage. The present study was planned to assess (i) oxidative stress during combined chronic exposure to arsenic and fluoride in drinking water, (ii) correlation of oxidative stress with cellular and DNA damage and (iii) mechanism of cellular damage using IR spectroscopy. Mice were exposed to arsenic and fluoride (50 ppm) either individually or in combination for 28 weeks. Arsenic or fluoride exposure individually led to a significant increase in reactive oxygen species (ROS) generation and associated oxidative stress in blood, liver and brain. Individual exposure to the two toxicants showed significant depletion of blood glutathione (GSH) and glucose 6-phosphate dehydrogenase (G6PD) activity, and single-stranded DNA damage using a comet assay in lymphocytes. We also observed an increase in the activity of ATPase, thiobarbituric acid reactive substance (TBARS) and a decreased, reduced and oxidized glutathione (GSH?:?GSSG) ratio in the liver and brain. Antioxidant enzymes like superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) were decreased and increased in liver and brain respectively. The changes were more pronounced in liver compared to brain suggesting liver to be more susceptible to the toxic effects of arsenic and fluoride. Interestingly, combined exposure to arsenic and fluoride resulted in less pronounced toxic effects compared to their individual effects based on biochemical variables, IR spectra, DNA damage (TUNEL and comet assays) and histopathological observations. IR spectra suggested that arsenic or fluoride perturbs the strength of protein and amide groups; however, the shifts in peaks were not pronounced during combined exposure. These results thus highlight the role of arsenic- or fluoride-induced oxidative stress, DNA damage and protein interaction as the major determinants of toxicity, along with the differential toxic effects during arsenic-fluoride interaction during co-exposure. The study further corroborates our earlier observations that at the higher concentration co-exposures to these toxicants do not elicit synergistic toxicity.",
Arsenic,1936146,"Modulation of arsenic toxicity-induced oxidative damage by coronatine pretreatment in sweet basil (Ocimum basilicum) seedlings Abstract: Coronatine (COR), a functional analogue of jasmonates, affects the accumulation of defense-related metabolites in plants. However, information on how its effects may be mediated by heavy metal stress is scanty. This study was carried out to determine the changes in some physiological parameters in sweet basil (Ocimum basilicum L.) seedlings pretreated with COR under arsenic (As) toxicity. COR was applied to seedlings at the three-leaf stage at 50 and 100 nanomolars (nmol·L?1). Arsenic at 150 and 300 ?mol·L?1 was imposed after completion of COR treatment. Toxic effects of As were reflected by the reduction in growth parameters and photosynthetic pigments and induction of lipid peroxidation coupled with enhancing hydrogen peroxide and electrolyte leakage in leaves. Under As toxicity, plants treated with COR significantly increased the fresh mass and relative water content in leaves. The increase was accompanied by decreased lipid peroxidation and hydrogen peroxide content and maintenance of chlorophyll pigments. COR supplement also increased the accumulation of phenolic compounds and proline content in the leaf of As-treated seedlings. Pretreatment with COR significantly enhanced activities of catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (POD) in basil leaves under As treatment. The results suggested that COR might alleviate As toxicity in sweet basil by activating antioxidant enzymes and inducing conservative components, thereby preventing membrane peroxidation.",
Arsenic,1345552,"Natural background levels for some ions in groundwater of the Campania region (southern Italy) Abstract: The aim of the study was the determination of the natural background levels (NBLs) for the ions Na+, Cl?, SO4 2?, As3+, F?, Fe2+, and Mn2+, in some groundwater bodies of the Campania region (southern Italy). The “Protocol to evaluate the natural background concentrations” proposed in 2009 by ISPRA (Italian Institute for Environmental Protection and Research) has been applied to the chemical data set of groundwater of the examined groundwater bodies. These analyses have also been examined following the guidelines of the BRIDGE project (Background cRiteria for the IDentification of Groundwater thrEshold). These approaches to evaluate the Threshold Values (TVs) and the NBLs, based on probability distribution functions, have been applied in many countries by various authors during the last 5 years. Changes applied to ISPRA Protocol in this study concern mainly the preselection criteria, in particular threshold values of specific ions, deriving from the aquifers geochemical features. The preselection criteria of the ISPRA Protocol have been merged with those of the BRIDGE Project in order to define a procedure suitable for the definition of the NBLs in the examined aquifers. The NBL of fluoride for the “Phlegrean Fields” and the “eastern Plain of Naples” groundwater bodies shows values deeply exceeding the reference value (REF) of 1,500 ?g/L, ranging between 3,600 and 15,000 ?g/L. The cause of this very high fluoride content is in the natural features of the aquifers constituted by volcanic and pyroclastic rocks. The volcanic origin of the aquifers is also the reason for the high arsenic content in “Phlegrean Fields” groundwater. Here the NBL calculated was about 47 ?g/L against the drinking water standard value of 10 ?g/L. The widespread high content of manganese and iron for the groundwater body of the “eastern Plain of Naples” is due to the reducing conditions related to the extensive marshlands present in the past. The very high NBL of all the examined ions for the groundwater body of “Ischia Island” depends on the existence of a geothermal system.",
Arsenic,627603,"Genetic toxicology of a paradoxical human carcinogen, arsenic: A review Abstract: Arsenic is widely distributed in nature in air, water and soil in the form of either metalloids or chemical compounds. It is used commercially, as pesticide, wood preservative, in the manufacture of glass, paper and semiconductors. Epidemiological and clinical studies indicate that arsenic is a paradoxical human carcinogen that does not easily induce cancer in animal models. It is one of the toxic compounds known in the environment. Intermittent incidents of arsenic contamination in ground water have been reported from several parts of the world. Arsenic containing drinking water has been associated with a variety of skin and internal organ cancers. The wide human exposure to this compound through drinking water throughout the world causes great concern for human health. In the present review, we have attempted to evaluate and update the mutagenic and genotoxic effects of arsenic and its compounds based on available literature.",
Arsenic,627953,"Arsenic methylation and skin cancer risk in southwestern Taiwan Abstract: Arsenic is a known carcinogen, but data are especially lacking on the health effects of low-level exposure, and on the health significance of methylation ability. We conducted a case-control study (76 cases and 224 controls from 1996 to 1999) in southwestern Taiwan to explore the association among primary and secondary arsenic methylation index (PMI and SMI, respectively), cumulative arsenic exposure (CAE), and the risk of skin cancer. As compared with the controls, the skin cancer group reported more sun exposure (P = 0.02) and had a lower BMI (P = 0.03), as well as lower education level (P = 0.01). Skin cancer patients and controls were similar with regard to age, gender, smoking and alcohol consumption. Given a low SMI (< or = 5), CAE > 15 mg/L-year was associated with an increased risk of skin cancer (OR, 7.48; 95% CI, 1.65-33.99) compared to a CAE < or = 2 mg/L-year. Given the same level of PMI, SMI, and CAE, men had a higher risk of skin cancer (OR, 4.04; 95% CI, 1.46-11.22) when compared to women. Subjects with low SMI and high CAE have a substantially increased risk of skin cancer. Males in all strata of arsenic exposure and methylation ability had a higher risk of skin cancer than women.",
Arsenic,1353792,ARSENIC IN EDIBLE MUSHROOMS Abstract: ,
Arsenic,656653,"A follow-up study of mortality among the arseniasis patients exposed to indoor combustion of high arsenic coal in Southwest Guizhou Autonomous Prefecture, China Abstract: OBJECTIVE: This study was directed to ascertain the mortality of a group of arseniasis patients in an endemic rural township in Southwest China, where the residents were exposed for decades to indoor combustion of high arsenic coal. METHODS: All the diagnosed arseniasis cases registered in 1991 were defined as the target population, which were assigned to three symptom subgroups by the severity of dermal lesions. The death cases were surveyed and checked. The follow-up period was 12.5 years. The standardized mortality ratio (SMR) of all death causes combined, all cancers combined, and the cancers at every site were analyzed. The age standardized mortality rates (ASMRs) were calculated in three subgroups using the procedure of standardization. RESULTS: One hundred and six death cases were recorded. Liver cirrhosis, non-melanotic skin cancer, lung and liver cancer were the four most prevalent death causes and referred to 70.8% (75/106) of the total death cases. The mortality of all death causes combined was not higher than that of the whole of China in 2001 (SMR = 0.76, 95% CI 0.63-0.93). The crude mortality rate of non-melanotic skin cancer in males reached up to 128.66/10(5). SMRs of lung cancer and larynx cancer in males (SMRs 2.84 and 27.27, 95% CIs 1.51-4.86 and 5.61-79.62, respectively) significantly exceeded the levels for all male Chinese. ASMRs of all death causes combined, all cancers combined and non-melanotic skin cancer in males of the severe dermal symptoms subgroup were significantly higher than those in medium and/or mild dermal symptom subgroups. CONCLUSIONS: A significantly increased mortality due to lung cancer and non-melanotic skin cancer was confirmed, alike the situation in other arseniasis endemic areas in the world. No significant elevation of mortality due to liver cancer and bladder cancer was observed. Male arseniasis patients diagnosed with severe skin lesions face higher risks of malignancies and of non-melanotic skin cancer in particular in the following years.",
Arsenic,2337083,"Assessing Exposure and Health Consequences of Chemicals in Drinking Water: Current State of Knowledge and Research Needs Abstract: BACKGROUND: Safe drinking water is essential for well-being. Although microbiological contamination remains the largest cause of water-related morbidity and mortality globally, chemicals in water supplies may also cause disease, and evidence of the human health consequences is limited or lacking for many of them. <br> <br>OBJECTIVES: We aimed to summarize the state of knowledge, identify gaps in understanding, and provide recommendations for epidemiological research relating to chemicals occurring in drinking water. Discussion: Assessing exposure and the health consequences of chemicals in drinking water is challenging. Exposures are typically at low concentrations, measurements in water are frequently insufficient, chemicals are present in mixtures, exposure periods are usually long, multiple exposure routes may be involved, and valid biomarkers reflecting the relevant exposure period are scarce. In addition, the magnitude of the relative risks tends to be small. <br> <br>CONCLUSION: Research should include well-designed epidemiological studies covering regions with contrasting contaminant levels and sufficient sample size; comprehensive evaluation of contaminant occurrence in combination with bioassays integrating the effect of complex mixtures; sufficient numbers of measurements in water to evaluate geographical and temporal variability; detailed information on personal habits resulting in exposure (e. g., ingestion, showering, swimming, diet); collection of biological samples to measure relevant biomarkers; and advanced statistical models to estimate exposure and relative risks, considering methods to address measurement error. Last, the incorporation of molecular markers of early biological effects and genetic susceptibility is essential to understand the mechanisms of action. There is a particular knowledge gap and need to evaluate human exposure and the risks of a wide range of emerging contaminants.",
Arsenic,2347622,"Effect of some operational parameters on the arsenic removal by electrocoagulation using iron electrodes Abstract: Arsenic contamination of drinking water is a global problem that will likely become more apparent in future years as scientists and engineers measure the true extent of the problem. Arsenic poisoning is preventable though as there are several methods for easily removing even trace amounts of arsenic from drinking water. In the present study, electrocoagulation was evaluated as a treatment technology for arsenic removal from aqueous solutions. The effects of parameters such as initial pH, current density, initial concentration, supporting electrolyte type and stirring speed on removal efficiency were investigated. It has been observed that initial pH was highly effective on the arsenic removal efficiency. The highest removal efficiency was observed at initial pH?=?4. The obtained experimental results showed that the efficiency of arsenic removal increased with increasing current density and decreased with increasing arsenic concentration in the solution. Supporting electrolyte had not significant effects on removal, adding supporting electrolyte decreased energy consumption. The effect of stirring speed on removal efficiency was investigated and the best removal efficiency was at the 150 rpm. Under the optimum conditions of initial pH 4, current density of 0.54 mA/cm(2), stirring speed of 150 rpm, electrolysis time of 30 minutes, removal was obtained as 99.50%. Energy consumption in the above conditions was calculated as 0.33 kWh/m(3). Electrocoagulation with iron electrodes was able to bring down 50 mg/L arsenic concentration to less than 10 ?g/L at the end of electrolysis time of 45 minutes with low electrical energy consumption as 0.52 kWh/m(3).",
Arsenic,79264,"Dose-response relationship between ischemic heart disease mortality and long-term arsenic exposure Abstract: The cardiovascular effects of inorganic arsenic have been documented, but the dose-response relationship between ischemic heart disease (ISHD) and long-term arsenic exposure remains to be elucidated. Mortality rates from ISHD among residents in 60 villages of the area in Taiwan with endemic arseniasis from 1973 through 1986 were analyzed to examine their association with arsenic concentration in drinking water. Based on 1 355 915 person-years and 217 ISHD deaths, the cumulative ISHD mortalities from birth to age 79 years were 3.4%, 3.5%, 4.7%, and 6.6%, respectively, for residents who lived in villages in which the median arsenic concentrations in drinking water were <0.1, 0.1 to 0.34, 0.35 to 0.59, and 0.6 mg/L. A cohort of 263 patients affected with blackfoot disease (BFD), a unique arsenic-related peripheral vascular disease, and 2293 non-BFD residents in the endemic area of arseniasis were recruited and followed up for an average period of 5.0 years. There was a monotonous biological gradient relationship between cumulative arsenic exposure through drinking artesian well water and ISHD mortality. The relative risks were 2.5, 4.0, and 6.5, respectively, for those who had a cumulative arsenic exposure of 0.1 to 9.9, 10.0 to 19.9, and 20.0 mg/L-years compared with those without the arsenic exposure after adjustment for age, sex, cigarette smoking, body mass index, serum cholesterol and triglyceride levels, and disease status for hypertension and diabetes through proportional-hazards regression analysis. BFD patients were found to have a significantly higher ISHD mortality than non-BFD residents, showing a multivariate-adjusted relative risk of 2.5 (95% CI, 1.1 to 5.4).",
Arsenic,1015694,"Poly(ADP-ribose) polymerase-1 inhibition by arsenite promotes the survival of cells with unrepaired DNA lesions induced by UV exposure Abstract: Human arsenic exposure is associated with increased risk of skin cancer and arsenite greatly enhances ultraviolet (UV)-induced skin tumors in a mouse model of carcinogenesis. Inhibition of DNA repair is one proposed mechanism for the observed co-carcinogenicity. We have previously demonstrated that low concentrations of arsenite inhibit Poly (ADP-ribose) polymerase (PARP)-1, thus interfering with DNA-repair process triggered by UV radiation. Since over-activation of PARP-1 often leads to apoptotic cell death, and unrepaired DNA lesions promote genomic instability and carcinogenesis, we hypothesized that inhibition of PARP-1 by arsenic may promote the survival of potentially &quot;initiated carcinogenic cells&quot;, i.e., cells with unrepaired DNA lesions. In the present study, we tested this hypothesis on UV-challenged HaCat cells. Cells were pretreated with 2 ?M arsenite for 24 hrs before UV exposure. Outcome parameters included apoptotic death rate, PARP-1 activation, apoptotic molecules and retention of DNA lesions. UV exposure induced PARP-1 activation and associated PAR production, apoptosis inducing factor (AIF) release, cytochrome C release and caspases activation, which led to apoptotic death in HaCat cells. Pretreatment with 2 ?M arsenite significantly inhibited UV-induced cell death as well as the associated molecular events. Notably, knockdown of PARP-1 with siRNA completely abolished the antagonism of arsenite. Furthermore, arsenite pretreatment led to long-term retention of UV-induced cyclobutane-pyrimidine dimers (CDPs). Together, these results suggest that low concentration of arsenite reduces UV-induced apoptosis via inhibiting PARP-1, thus promoting the survival of cells with unrepaired DNA lesions, which may be an important mechanism underlying arsenic co-carcinogenic action.",
Arsenic,628694,"Identification of the major arsenic-binding protein in rat plasma as the ternary dimethylarsinous-hemoglobin-haptoglobin complex Abstract: Chronic exposure to arsenic causes a wide range of diseases such as hyperkeratosis, cardiovascular diseases, and skin, lung, and bladder cancers, and millions of people are chronically exposed to arsenic worldwide. However, little is known about the mechanisms underlying these toxic actions. The metabolism of arsenic is essential for understanding the toxic actions. Here, we identified the major arsenic-binding protein (As-BP) in the plasma of rats after oral administration of arsenite by the use of two different HPLC columns, gel filtration and anion exchange ones, coupled with an inductively coupled argon plasma mass spectrometer (ICP MS). The molecular mass of the As-BP was estimated to be 90 kDa based on results using the former column, and arsenic bound to this protein only in the form of dimethylarsinous acid (DMA (III)) in the plasma in vivo. In addition, the purified As-BP was shown to consist of two different proteins, haptoglobin (Hp) of 37 kDa (three bands) and the hemoglobin (Hb) alpha chain of 14 kDa (single band), using sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), respectively, suggesting that the As-BP was the ternary DMA (III)-Hb-Hp complex. To confirm the present observations, an arsenic-binding assay was carried out in vitro . Although DMA (III) bound directly to fresh rat plasma proteins, they were different from that identified in vivo. However, when a DMA (III)-exposed rat RBC lysate (DMA (III) binds to Hb in rat RBCs) was added to control rat plasma, a new arsenic peak increased at the expense of the arsenic-Hb one. Furthermore, this new arsenic peak was consistent with the As-BP identified in the plasma in vivo, suggesting that arsenic bound to Hb further binds to haptoglobin (Hp), forming the ternary As-Hb-Hp complex.",
Arsenic,628109,"Lung cancer mortality reduction after installation of tap-water supply system in an arseniasis-endemic area in southwestern Taiwan Abstract: Arsenic has been well documented as the major risk factor for blackfoot disease (BFD), a unique peripheral vascular disease (PVD) that was endemic in the Southwestern coast of Taiwan, where residents had used high-arsenic artesian well water for more than 50 years. Long-term arsenic exposure has also been reported to associated with lung cancer mortality in a dose-response relationship. A tap-water supply system was implemented in the early 1960s in the BFD-endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study is to examine whether lung cancer mortality decreased after the improvement of drinking water supply system through elimination of arsenic exposure from artesian well water. Standardized mortality ratios (SMRs) for lung cancer were calculated for the BFD-endemic area for the years 1971-2000. The study results show that mortality from lung cancer declined gradually after the improvement of drinking water supply system to eliminate arsenic exposure from artesian well water. Based on the reversibility criterion, the association between arsenic exposure and lung cancer mortality is likely to be causal.",
Arsenic,626922,"Hepatoprotective activity of liposomal flavonoid against arsenite-induced liver fibrosis Abstract: Arsenic, the environmental metalloid toxicant, is known to induce oxidative damage to liver and produce hepatic fibrosis. The theme of our study was to optimize and evaluate the therapeutic efficacy of galactosylated liposomal flavonoidal antioxidant, quercetin (QC), in combating arsenic-induced hepatic fibrogenesis. The rats of the hepatic damage group were injected s.c. a single dose of sodium arsenite (NaAsO(2)) (100.06 microM/kg b. wt. in 0.5 ml of physiological saline). Hepatocytes and stellate cells were separated. Mitochondrial membranes were isolated from all those separated cells. Oxidative damage was monitored at different isolated subcellular parts of different hepatic cells. Liver fibrosis was also induced by the injection of NaAsO(2). Galactosylated liposomal QC injection before NaAsO(2) treatment checked fibrogenesis completely by protecting the liver from oxidative attack in cellular and subcellular levels. The maximal protections from hepatocellular and fatty metamorphosis, necrosis, Kupffer cell hyperplasia, fibrosis, and in the deposition of collagen contents were observed and reconfirmed by our histopathological and histochemical analysis when rats were treated with galactosylated liposomal QC before NaAsO(2) injection. Application of galactosylated liposomal QC may be a potent therapeutic approach for NaAsO(2)-induced fibrogenesis through a complete protection against oxidative attack in cellular and subcellular parts of rat liver.",
Arsenic,1015678,"Phytochelatins play a key role in arsenic accumulation and tolerance in the aquatic macrophyte Wolffia globosa Abstract: The rootless duckweed Wolffia globosa can accumulate and tolerate relatively large amounts of arsenic (As); however, the underlying mechanisms were unknown. W. globosa was exposed to different concentrations of arsenate with or without l-buthionine sulphoximine (BSO), a specific inhibitor of ?-glutamylcysteine synthetase. Free thiol compounds and As(III)-thiol complexes were identified and quantified using HPLC - high resolution ICP-MS - accurate mass ESI-MS. Without BSO, 74% of the As accumulated in the duckweed was complexed with phytochelatins (PCs), with As(III)-PC(4) and As(III)-PC(3) being the main species. BSO was taken up by the duckweed and partly deaminated. The BSO treatment completely suppressed the synthesis of PCs and the formation of As(III)-PC complexes, and also inhibited the reduction of arsenate to arsenite. BSO markedly decreased both As accumulation and As tolerance in W. globosa. The results demonstrate an important role of PCs in detoxifying As and enabling As accumulation in W. globosa.",
Arsenic,656676,"A redox-linked novel pathway for arsenic-mediated RET tyrosine kinase activation Abstract: We examined the biochemical effects of arsenic on the activities of RET proto-oncogene (c-RET protein tyrosine kinases) and RET oncogene (RET-MEN2A and RET-PTC1 protein tyrosine kinases) products. Arsenic activated c-RET kinase with promotion of disulfide bond-mediated dimerization of c-RET protein. Arsenic further activated RET-MEN2A kinase, which was already 3- to 10-fold augmented by genetic mutation compared with c-RET kinase activity, with promotion of disulfide bond-mediated dimerization of RET-MEN2A protein (superactivation). Arsenic also increased extracellular domain-deleted RET-PTC1 kinase activity with promotion of disulfide bond-mediated dimerization of RET-PTC1 protein. Arsenic increased RET-PTC1 kinase activity with cysteine 365 (C365) replaced by alanine with promotion of dimer formation but not with cysteine 376 (C376) replaced by alanine. Our results suggest that arsenic-mediated regulation of RET kinase activity is dependent on conformational change of RET protein through modulation of a special cysteine sited at the intracellular domain in RET protein (relevant cysteine of C376 in RET-PTC1 protein). Moreover, arsenic enhanced the activity of immunoprecipitated RET protein with increase in thiol-dependent dimer formation. As arsenic (14.2 microM) was detected in the cells cultured with arsenic (100 microM), direct association between arsenic and RET in the cells might modulate dimer formation. Thus, we demonstrated a novel redox-linked mechanism of activation of arsenic-mediated RET proto-oncogene and oncogene products.",
Arsenic,1453801,"Methylated trivalent arsenicals are potent inhibitors of glucose stimulated insulin secretion by murine pancreatic islets Abstract: Epidemiologic evidence has linked chronic exposure to inorganic arsenic (iAs) with an increased prevalence of diabetes mellitus. Laboratory studies have identified several mechanisms by which iAs can impair glucose homeostasis. We have previously shown that micromolar concentrations of arsenite (iAs(III)) or its methylated trivalent metabolites, methylarsonite (MAs(III)) and dimethylarsinite (DMAs(III)), inhibit the insulin-activated signal transduction pathway, resulting in insulin resistance in adipocytes. Our present study examined effects of the trivalent arsenicals on insulin secretion by intact pancreatic islets isolated from C57BL/6 mice. We found that 48-hour exposures to low subtoxic concentrations of iAs(III), MAs(III) or DMAs(III) inhibited glucose-stimulated insulin secretion (GSIS), but not basal insulin secretion. MAs(III) and DMAs(III) were more potent than iAs(III) as GSIS inhibitors with estimated IC(50)?0.1?M. The exposures had little or no effects on insulin content of the islets or on insulin expression, suggesting that trivalent arsenicals interfere with mechanisms regulating packaging of the insulin transport vesicles or with translocation of these vesicles to the plasma membrane. Notably, the inhibition of GSIS by iAs(III), MAs(III) or DMAs(III) could be reversed by a 24-hour incubation of the islets in arsenic-free medium. These results suggest that the insulin producing pancreatic ?-cells are among the targets for iAs exposure and that the inhibition of GSIS by low concentrations of the methylated metabolites of iAs may be the key mechanism of iAs-induced diabetes.",
Arsenic,1508674,"Characterization of Heavy-Metal Contamination in Surface Sediments of the Minho River Estuary by way of Factor Analysis Abstract: Surface sediments were collected in August 2009 from 49 sites along the Minho estuary (between Tui and Caminha) and analyzed for grain size, organic carbon (C(org)) and total nitrogen (N(tot)) contents, and major (silicon [Si], aluminum [Al], iron [Fe], calcium [Ca], magnesium [Mg], sodium [Na], potassium [K], titanium [Ti], and mangesese [Mn]) and trace element (arsenic [As], chromium [Cr], copper [Cu], mercury [Hg], lithium [Li], lead [Pb], rubidium [Rb], tin [Sn], and zinc [Zn]) concentrations. Factor analysis was used to decrease 22 selected variables into 4 factors accounting for 85.9 % of the total variance explained, suggesting distinct elemental sources or sediment components affecting their spatial distributions. Although factors 1 (detrital component; elements strongly associated with fine- [Na, Mg, Ti, Li, Cr, Cu, Fe, Al, Zn, Ca, and As] and coarse-grained sediments [Si, K, Rb; mean grain-size [M(GS)]) and 3 (Fe-Mn oxyhydroxide sediment component; Fe, Mn, As, fine fraction) are interpreted as reflecting predominance of natural contributions, factors 2 (urban and industrial contamination: sediment components [Pb, Hg, organic carbon [C(org)], total nitrogen [N(tot)] and 4 (components associated with contamination by nautical activities; the association of tin [Sn] and calcium [Ca]) seem to indicate anthropogenic contributions). Nevertheless, the influence of elemental contributions derived from tungsten (W)-Sn mineralizations and those resulting from mining activities can also contribute to the obtained geochemical associations and should be considered. Spatial distribution of dominant factor scores shows the dominance of factors 2 and 4 between Tui and Vila Nova de Cerveira, whereas samples dominated by factors 3 and 1 are found between Ilha da Boega and Seixas and in the Caminha areas, respectively. Despite the dominance of factor score 1 in the Caminha area, the distribution pattern of dominant factor scores shows samples dominated by other factor scores that can be explained by dredging activities in this river sector that restore ancient sedimentary characteristics or expose contaminated sediments. Through the identification of sample locations dominated by factors associated with contamination, it will be possible to select them as priority areas where new environmental (e.g., toxicity tests, organic Sn compounds, tracers of sewage contamination) studies should be implemented in the future.",
Arsenic,1327159,"Comparisons of survival time estimates for Niigata Prefecture (Japan) residents exposed to ingested arsenic Abstract: Survival analysis was used to analyze follow-up data on an arsenic-poisoned area, identified in 1959, in order to assess the effect of arsenic on survival time. The subjects were 443 residents of Namiki-cho, Nakajo-machi, Niigata Prefecture, Japan, who ingested well water contaminated with arsenic between 1955 and 1959. Their exposure to arsenic was only by ingestion of well water. We observed this historical cohort from October 1959 to February 1992. Survival time was calculated in two ways: from 1959 (the end of exposure) until death or until 1992 (the termination of follow-up); or from birth until death or until 1992. The entire cohort was divided into two groups according to the arsenic concentration measured in the wells in 1959. Different survival curves of the two were drawn using the Kaplan–Meier method. The lifetime survival curves indicate that the lifetimes of arsenic-exposed residents were significantly shorter than that of the low-dose exposure group or of unexposed residents. From the differences in the estimated lifetime survival curves, the effect of arsenic on the mortality of the residents can be inferred.",
Arsenic,1026549,"Genomic methylation of peripheral blood leukocyte DNA: Influences of arsenic and folate in Bangladeshi adults Abstract: Background: Studies in cell culture and animal models indicate that arsenic exposure induces modifications in DNA methylation, including genome-wide DNA hypomethylation. It is not known whether arsenic exposure influences genomic DNA methylation in human populations chronically exposed to arsenic-contaminated drinking water. Objective: The objective of this study was to determine whether arsenic is associated with genomic hypomethylation of peripheral blood leukocyte (PBL) DNA in Bangladeshi adults who are chronically exposed to arsenic. We also investigated whether arsenicinduced alterations inDNAmethylation may be influenced by folate nutritional status. Design: PBLDNAmethylation and concentrations of plasma folate, plasma arsenic, and urinary arsenic were assessed in 294 adults in Araihazar, Bangladesh. Genomic PBL DNA methylation was measured by using a [3H]-methyl incorporation assay. Results: Urinary arsenic, plasma arsenic, and plasma folate were positively associated with the methylation of PBLDNA(P 0.009, 0.03, and 0.03, respectively). Stratification of participants by folate nutritional status [ 9 nmol/L (n 190) or 9 nmol/L (n 104)] showed that the associations between arsenic exposure and methylation of PBL DNA were restricted to persons with folate concentrations 9 nmol/L. Conclusions: Contrary to our a priori hypothesis, arsenic exposure was positively associated with genomic PBL DNA methylation in a dose-dependent manner. This effect is modified by folate, which suggests that arsenic-induced increases in DNA methylation cannot occur in the absence of adequate folate. The underlying mechanisms and physiologic implications of increased genomic DNA methylation are unclear, and they warrant further study.",
Arsenic,710863,"The association between arsenic and children's intelligence: A meta-analysis Abstract: This present study was undertaken to investigate whether arsenic exposure increases the risk of children's low intelligence quotient (IQ) in China. MEDLINE, SCI, CNKI, and CBM search were organized for all documents published, in English and Chinese, between 1988 and 2008 using the following keywords: arsenic, intelligence, and IQ. As a result, four cross-sectional studies that assessed the development of low IQ in children who had been exposed to arsenic earlier in their life were included in this study. The summary weighted mean difference of IQ was calculated in this meta-analyses, when arsenicosis areas or slight arsenicosis areas were compared with non-arsenicosis areas; it is -6.85 (95% confidence interval [CI] = -8.30 to -5.41; p &lt; 0.01, using a fixed effect model) and -6.54 (95%CI = -8.93 to -4.15; p &lt; 0.01, using a random effect model), which means that children who live in an arsenicosis area or a slight arsenicosis area have lower IQ than those who live in a non-arsenicosis area, and there may be a strong association between arsenic and children's intelligence.",
Arsenic,1252416,ENHANCEMENT OF UV-MUTAGENESIS BY LOW CONCENTRATIONS OF ARSENITE IN ESCHERICHIA-COLI Abstract: ,
Arsenic,627124,"Methylated trivalent arsenicals as candidate ultimate genotoxic forms of arsenic: Induction of chromosomal mutations but not gene mutations Abstract: Arsenic is a prevalent human carcinogen whose mutagenicity has not been characterized fully. Exposure to either form of inorganic arsenic, As(III) or As(V), can result in the formation of at least four organic metabolites: monomethylarsonic acid, monomethylarsonous acid (MMA(III)), dimethylarsinic acid, and dimethylarsinous acid (DMA(III)). The methylated trivalent species, as well as some of the other species, have not been evaluated previously for the induction of chromosome aberrations, sister chromatid exchanges (SCE), or toxicity in cultured human peripheral blood lymphocytes; for mutagenicity in L5178Y/Tk(+/-) mouse lymphoma cells or in the Salmonella reversion assay; or for prophage-induction in Escherichia coli. Here we evaluated the arsenicals in these assays and found that MMA(III) and DMA(III) were the most potent clastogens of the six arsenicals in human lymphocytes and the most potent mutagens of the six arsenicals at the Tk(+/-) locus in mouse lymphoma cells. The dimethylated arsenicals were also spindle poisons, suggesting that they may be ultimate forms of arsenic that induce aneuploidy. Although the arsenicals were potent clastogens, none were potent SCE inducers, similar to clastogens that act via reactive oxygen species. None of the six arsenicals were gene mutagens in Salmonella TA98, TA100, or TA104; and neither MMA(III) nor DMA(III) induced prophage. Our results show that both methylated As(V) compounds were less cytotoxic and genotoxic than As(V), whereas both methylated As(III) compounds were more cytotoxic and genotoxic than As(III). Our data support the view that MMA(III) and DMA(III) are candidate ultimate genotoxic forms of arsenic and that they are clastogens and not gene mutagens. We suggest that the clastogenicity of the other arsenicals is due to their metabolism by cells to MMA(III) or DMA(III).",
Arsenic,1018808,"Clustering of hepatotoxins based on mechanism of toxicity using gene expression profiles Abstract: Microarray technology, which allows one to quantitate the expression of thousands of genes simultaneously, has begun to have a major impact on many different areas of drug discovery and development. The question remains of whether microarray analysis and gene expression signature profiles can be applied to the field of toxicology. To date, there are very few published studies showing the use of microarrays in toxicology and important questions remain regarding the predictability and accuracy of applying gene expression profiles to toxicology. To begin to address these questions, we have treated rats with 15 different known hepatotoxins, including allyl alcohol, amiodarone, Aroclor 1254, arsenic, carbamazepine, carbon tetrachloride, diethylnitrosamine, dimethylformamide, diquat, etoposide, indomethacin, methapyrilene, methotrexate, monocrotaline, and 3-methylcholanthrene. These agents cause a variety of hepatocellular injuries including necrosis, DNA damage, cirrhosis, hypertrophy, and hepatic carcinoma. Gene expression analysis was done on RNA from the livers of treated rats and was compared against vehicle-treated controls. The gene expression results were clustered and compared to the histopathology findings and clinical chemistry values. Our results show strong correlation between the histopathology, clinical chemistry, and gene expression profiles induced by the agents. In addition, genes were identified whose regulation correlated strongly with effects on clinical chemistry parameters. Overall, the results suggest that microarray assays may prove to be a highly sensitive technique for safety screening of drug candidates and for the classification of environmental toxins.",
Arsenic,1252754,"Trivalent methylated arsenical-induced phosphatidylserine exposure and apoptosis in platelets may lead to increased thrombus formation Abstract: Trivalent methylated metabolites of arsenic, monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)), have been found highly reactive and toxic in various cells and in vivo animal models, suggesting their roles in the arsenic-associated toxicity. However, their effects on cardiovascular system including blood cells, one of the most important targets for arsenic toxicity, remain poorly understood. Here we found that MMA(III) and DMA(III) could induce procoagulant activity and apoptosis in platelets, which play key roles in the development of various cardiovascular diseases (CVDs) through excessive thrombus formation. In freshly isolated human platelets, treatment of MMA(III) resulted in phosphatidylserine (PS) exposure, a hallmark of procoagulant activation, accompanied by distinctive apoptotic features including mitochondrial membrane potential disruption, cytochrome c release, and caspase-3 activation. These procoagulant activation and apoptotic features were found to be mediated by the depletion of protein thiol and intracellular ATP, and flippase inhibition by MMA(III), while the intracellular calcium increase or reactive oxygen species generation was not involved. Importantly, increased platelet procoagulant activity by MMA(III) resulted in enhanced blood coagulation and excessive thrombus formation in a rat in vivo venous thrombosis model. DMA(III) also induced PS-exposure with apoptotic features mediated by protein thiol depletion, which resulted in enhanced thrombin generation. In summary, we believe that this study provides an important evidence for the role of trivalent methylated arsenic metabolites in arsenic-associated CVDs, giving a novel insight into the role of platelet apoptosis in toxicant-induced cardiovascular toxicity.",
Arsenic,8555,"Arsenic contamination of drinking water and foodstuffs causing endemic chronic poisoning Abstract: An ivestigation on patients with chronic arsenic poisoning from the city of Antofagasta, Chile, and concentrations of arsenic in drinking water was performed. During the period 1968-1971, a total of 457 patients (208 males, 249 females) bearing cutaneous lesions (leukoderma, melanoderma, hyperkeratosis, squamous-cell carcinoma) were registered. Children (0-15 years of age) accounted for 69.2% of male cast 77.5% of female cases. These patients exhibited high arsenic content in the hair. The mean concentration of arsenic in drinking water in the period 1968-1969 was 0.58 ppm versus 0.08 ppm in 1971, differing by a factor of 7.2. Such difference was due to a Filter Plant which started operation in May 1970. The average incidence rates per 100,000 population for cases with cutaneous lesions in 1968-1969 were 145.5 for males and 168.0 for females. The incidence rates decreased in 1971 to 9.1 for males and 10.0 for females. Among the 337 registered children, 5 died showing thrombosis of brain arteries, thrombosis of mesenteric artery, restriction of lumen of coronary arteries, and/or myocardial infarction. Of the 64 registered adult males, 2 developed multiple skin carcinomata with lymph node metastases.",
Arsenic,627290,"Drinking water arsenic in Utah: A cohort mortality study Abstract: The association of drinking water arsenic and mortality outcome was investigated in a cohort of residents from Millard County, Utah. Median drinking water arsenic concentrations for selected study towns ranged from 14 to 166 ppb and were from public and private samples collected and analyzed under the auspices of the State of Utah Department of Environmental Quality, Division of Drinking Water. Cohort members were assembled using historical documents of the Church of Jesus Christ of Latter-day Saints. Standard mortality ratios (SMRs) were calculated. Using residence history and median drinking water arsenic concentration, a matrix for cumulative arsenic exposure was created. Without regard to specific exposure levels, statistically significant findings include increased mortality from hypertensive heart disease [SMR = 2.20; 95% confidence interval (CI), 1.36-3.36], nephritis and nephrosis (SMR = 1.72; CI, 1.13-2.50), and prostate cancer (SMR = 1.45; CI, 1.07-1. 91) among cohort males. Among cohort females, statistically significant increased mortality was found for hypertensive heart disease (SMR = 1.73; CI, 1.11-2.58) and for the category of all other heart disease, which includes pulmonary heart disease, pericarditis, and other diseases of the pericardium (SMR = 1.43; CI, 1.11-1.80). SMR analysis by low, medium, and high arsenic exposure groups hinted at a dose relationship for prostate cancer. Although the SMRs by exposure category were elevated for hypertensive heart disease for both males and females, the increases were not sequential from low to high groups. Because the relationship between health effects and exposure to drinking water arsenic is not well established in U.S. populations, further evaluation of effects in low-exposure populations is warranted.",
Arsenic,8507,The chemistry of sulfur and arsenic in airborne copper smelter particulates Abstract: HEEP COPYRIGHT: BIOL ABS. UTAH USA,
Arsenic,1936157,Sorption of As(V) by Aluminum-Modified Crop Straw-Derived Biochars Abstract: ,
Arsenic,1508561,"Protective benefits of deep tube wells against childhood diarrhea in Matlab, Bangladesh Abstract: Objectives. We investigated whether deep tube wells installed to provide arsenic-free groundwater in rural Bangladesh have the added benefit of reducing childhood diarrheal disease incidence. Methods. We recorded cases of diarrhea in children younger than 5 years in 142 villages of Matlab, Bangladesh, during monthly community health surveys in 2005 and 2006. We surveyed the location and depth of 12?018 tube wells and integrated these data with diarrhea data and other data in a geographic information system. We fit a longitudinal logistic regression model to measure the relationship between childhood diarrhea and deep tube well use. We controlled for maternal education, family wealth, year, and distance to a deep tube well. Results. Household clusters assumed to be using deep tube wells were 48.7% (95% confidence interval?=?27.8%, 63.5%) less likely to have a case of childhood diarrhea than were other household clusters. Conclusions. Increased access to deep tube wells may provide dual benefits to vulnerable populations in Matlab, Bangladesh, by reducing the risk of childhood diarrheal disease and decreasing exposure to naturally occurring arsenic in groundwater. (Am J Public Health. Published online ahead of print February 14, 2013: e1-e5. doi:10.2105/AJPH.2012.300975).",
Arsenic,1677652,"The optimization of As(V) removal over mesoporous alumina by using response surface methodology and adsorption mechanism Abstract: The Box-Behnken Design of the response surface methodology was employed to optimize four most important adsorption parameters (initial arsenic concentration, pH, adsorption temperature and time) and to investigate the interactive effects of these variables on arsenic(V) adsorption capacity of mesoporous alumina (MA). According to analysis of variance (ANOVA) and response surface analyses, the experiment data were excellent fitted to the quadratic model, and the interactive influence of initial concentration and pH on As(V) adsorption capacity was highly significant. The predicted maximum adsorption capacity was about 39.06mg/g, and the corresponding optimal parameters of adsorption process were listed as below: time 720min, temperature 52.8°C, initial pH 3.9 and initial concentration 130mg/L. Based on the results of arsenate species definition, FT-IR and pH change, As(V) adsorption mechanisms were proposed as follows: (1) at pH 2.0, H3AsO4 and H2AsO4(-) were adsorbed via hydrogen bond and electrostatic interaction, respectively; (2) at pH 6.6, arsenic species (H2AsO4(-) and HAsO4(2-)) were removed via adsorption and ion exchange, (3) at pH 10.0, HAsO4(2-) was adsorbed by MA via ion exchange together with adsorption, while AsO4(3-) was removed by ion exchange.",
Arsenic,628004,"Cell cycle inhibition by sodium arsenite in primary embryonic rat midbrain neuroepithelial cells Abstract: Arsenite (As3+) exposure during development has been associated with neural tube defects and other structural malformations, and with behavioral alterations including altered locomotor activity and operant learning. The molecular mechanisms underlying these effects are uncertain. Because arsenic can cross the placenta and accumulate in the developing neuroepithelium, we examined cell cycling effects of sodium arsenite (As3+ 0, 0.5, 1, 2, and 4 microM) on embryonic primary rat midbrain (gestational day [GD] 12) neuroepithelial cells over 48 h. There was a concentration- and time-dependent As3+-induced reduction in cell viability assessed by neutral red dye uptake assay but minimal apoptosis at concentrations below 4 microM. Morphologically, apoptosis was not apparent until 4 microM at 24 h, which was demonstrated by a marginal but statistically significant increase in cleaved caspase-3/7 activity. Cell cycling effects over several rounds of replication were determined by continuous 5-bromo-2'-deoxyuridine (BrdU) labeling and bivariate flow cytometric Hoechst-Propidium Iodide analysis. We observed a time- and concentration-dependent inhibition of cell cycle progression as early as 12 h after exposure (> or =0.5 microM). In addition, data demonstrated a concentration-dependent increase in cytostasis within all cell cycle phases, a decreased proportion of cells able to reach the second cell cycle, and a reduced cell cycle entry from gap 1 phase (G1). The proportion of affected cells and the severity of the cell cycle perturbation, which ranged from a decreased transition probability to complete cytostasis in all cell cycle phases, were also found to be concentration-dependent. Together, these data support a role for perturbed cell cycle progression in As3+ mediated neurodevelopmental toxicity.",
Arsenic,1026214,"Arsenic in seaweed--forms, concentration and dietary exposure Abstract: This study has measured the content of total and inorganic forms of arsenic in seaweed available on retail sale for consumption, to provide data for dietary exposure estimates and to support advice to consumers. A total of 31 samples covering five varieties of seaweed were collected from various retail outlets across London and the internet. All of the samples were purchased as dried product. For four of the five varieties, soaking was advised prior to consumption. The recommended method of preparation for each individual sample was followed, and total and inorganic arsenic were analysed both before and after preparation. The arsenic remaining in the water used for soaking was also measured. Arsenic was detected in all samples with total arsenic at concentrations ranging from 18 to 124 mg/kg. Inorganic arsenic, which can cause liver cancer, was only found in the nine samples of hijiki seaweed that were analysed, at concentrations in the range 67-96 mg/kg. Other types of seaweed were all found to contain less than 0.3mg/kg inorganic arsenic, which was the limit of detection for the method used. Since consumption of hijiki seaweed could significantly increase dietary exposure to inorganic arsenic, the UK Food Standards Agency (FSA) issued advice to consumers to avoid eating it.",
Arsenic,1017042,"Effects on levels of glutathione and some related enzymes in tissues after an acute arsenic exposure in rats and their relationship to dietary protein deficiency Abstract: Arsenic is a potent toxin, carcinogen and modulator of antioxidant defense system. In this study, male rats of Wistar strain, maintained on either 18% or 6% protein (casein) diet, received an acute i.p. exposure to sodium arsenite (As3+) at its LD50 dose (15.86 mg/kg body weight). One hour after the arsenic exposure, glutathione (GSH) concentration was significantly depleted and lipid peroxidation was increased. A relationship between any two of tissue arsenic concentrations, GSH levels and lipid peroxidation values was observed only for liver when the proportional changes of respective parameters in either of the dietary groups of animals were compared. This suggests that, in liver, arsenic metabolism appears dependant upon the GSH concentration. Acute arsenic exposure significantly increased the glutathione peroxidase (GPx) activity in liver of both dietary groups and in kidney of only the 18% protein-fed group of animals. The glutathione-S-transferase (GST) activity significantly decreased in liver of the 18% protein-fed animals while GST increased in kidney of both the 18% and the 6% protein-fed groups. No significant change in glutathione reductase (GR) or glucose-6-phosphate dehydrogenase (G6PDH) activity was observed. In the present investigation, liver as a whole seems to be more affected in terms of GSH level and GST activity. The mode of responses of GPx and GR activities as well as the unaltered G6PDH activity might result in arsenic-induced GSH depletion and increase in lipid peroxidation. The animals of the 6% protein-fed group, appeared to be affected less in terms of tissue arsenic concentration, GSH level and GST activity. lipid peroxidation",
Arsenic,626908,"Arsenic contamination in drinking water and skin manifestations in lowland Nepal: The first community-based survey Abstract: A community-based, dose-response study on arsenic contamination was conducted in three communities in Terai in lowland Nepal. The arsenic concentration of all the tube wells in use (n = 146) and the prevalence of arsenic-induced skin manifestation among 1,343 (approximately 80% of the inhabitants) subjects indicated the existence of a highly contaminated area in Terai. It was found that overall prevalence of arsenicosis among the subjects > or = 15 years old was 6.9%, which was comparable to those found by the same examiner in arsenic-contaminated areas in Bangladesh, and that males had prevalence a twice as high as females, which could not be explained by the difference in the exposure level.",
Arsenic,1677535,"K(MoO2)4O3(AsO4) Abstract: A new compound with a non-centrosymmetric structure, potassium tetra-kis-[dioxomolybdenum(IV)] arsenate trioxide, K(MoO2)4O3(AsO4), has been synthesized by a solid-state reaction. The [(MoO2)4O3(AsO4)](+) three-dimensional framework consists of single arsenate AsO4 tetra-hedra, MoO6 octa-hedra, MoO5 bipyramids and bi-octa-hedral units of edge-sharing Mo2O10 octa-hedra. The [Mo2O8]? octa-hedral chains running along the a-axis direction are connected through their corners to the AsO4 tetra-hedra, MoO6 octa-hedra and MoO5 bipyramids, so as to form large tunnels propagating along the a axis in which the K(+) cations are located. This structure is compared with compounds containing M 2O10 (M = Mo, V, Fe) dimers and with those containing M 2O8 (M = V) chains.",
Arsenic,2298720,"Project update: Evaluating the community health legacy of WWI chemical weapons testing Abstract: The Spring Valley community of Washington, District of Columbia, was built on the site of a World War I chemical weapons lab where testing activities had distributed arsenic to surface soil and waste disposal had resulted in localized subsurface contamination. In previous work, findings were suggestive of potential site-related health issues, although no evidence of cancer clustering was found. In follow-up, we updated the community health assessment and explored time trends for several arsenic-related cancers. Health indicators continue to be very good in Spring Valley. For all major causes of mortality, Spring Valley rates were lower than United States (US) rates with most substantially lower (20-80 %); rates for heart diseases, Alzheimer's, and essential hypertension and related kidney disease were only slightly lower than US rates (3-8 %). Incidence and mortality rates for the selected cancers in the Spring Valley area were lower than US rates. Small non-statistically significant increasing time trends were observed in Spring Valley for incidence of two arsenic-related cancers: bladder and lung and bronchus. A moderate statistically significant increasing rate trend was observed for lung and bronchus cancer mortality in Spring Valley (p &lt; 0.01). Lung and bronchus cancer mortality rates were also increasing in the Chevy Chase community, the local comparison area closely matched to Spring Valley on important demographic variables, suggesting that the observed increases may not be site-related. A full profile of common cancer site rates and trends for both study areas was suggested to better understand the rate trend findings but no epidemiological study was recommended.",
Arsenic,1579403,Arsenic accumulation in Ocimum spp. and its effect on growth and oil constituents Abstract: ,
Arsenic,1579282,"Left sided colorectal adenomatous polyps have more risk for high grade dysplasia Abstract: Colorectal cancer is the second leading cause of cancer death worldwide. Through risk assessment of malignancy in polyps, screening programs can achieve the best results. This study aimed to determine the association between the grade of dysplasia and the location of colorectal polyps. 240 colorectal adenomatous polyps which were referred to department of pathology at Rasoul-e-Akram Hospital between 2005 and 2009 met the inclusion criteria. Demographic data and information about size of polyps, grade of dysplasia and location of polyps were collected and analyzed by Chi-square and t-test. 124 (58.8%) patients were male and 87 (41.2%) were female. The mean age of the patients was 61.6 years. 47 (19.6%) polyps were right-sided and 193 (80.4%) were left sided. 39 (16.2%) polyps had high grade dysplasia. 27 (12.8%) patients had 56 synchronous polyps (23.3%). 176 (73.3%), 39 (16.2%) and 25 (10.5%) polyps were of tubular, tubulovillous and villous types respectively. The greatest dimension of 110 (45.8%) polyps was &amp;lt;0.5 cm, 97 (40.4%) 0.5-1 cm, 22 (9.2%) between 1 and 2 cm and finally 11 (4.6%) &amp;gt;2 cm. High grade dysplasia was detected in 3 (6.3 %) of right-sided and 36 (18.6%) of left-sided polyps. The obtained results revealed that size of polyp and amount of villous component were strongly associated with high grade dysplasia. Left side location of polyps was independently associated with high grade dysplasia. Left-sided colorectal polyps must be treated more seriously, especially the larger ones with villous component. There was no association between age and gender and the grade of dysplasia.",
Arsenic,1026302,"Arsenic speciation analysis in human saliva Abstract: <strong>BACKGROUND: </strong>Determination of arsenic species in saliva is potentially useful for biomonitoring of human exposure and studying arsenic metabolism. Arsenic speciation in saliva has not been reported previously.<br /><br /><strong>METHODS: </strong>We separated arsenic species in saliva using liquid chromatography (LC) and quantified them by inductively coupled plasma mass spectrometry. We further confirmed the identities of arsenic species by LC coupled with electrospray ionization tandem mass spectrometry. These methods were successfully applied to the determination of arsenite (As(III)), arsenate (As(V)), and their methylation metabolites, monomethylarsonic acid (MMA(V)), and dimethylarsinic acid (DMA(V)), in &gt;300 saliva samples collected from people who were exposed to varying concentrations of arsenic.<br /><br /><strong>RESULTS: </strong>The mean (range) concentrations (microg/L) in the saliva samples from 32 volunteers exposed to background levels of arsenic were As(III) 0.3 [not detectable (ND) to 0.7], As(V) 0.3 (ND to 0.5), MMA(V) 0.1 (ND to 0.2), and DMA(V) 0.7 (ND to 2.6). Samples from 301 people exposed to increased concentrations of arsenic in drinking water showed detectable As(III) in 99%, As(V) in 98%, MMA(V) in 80%, and DMA(V) in 68% of samples. The mean (range) concentrations of arsenic species in these saliva samples were (in microg/L) As(III) 2.8 (0.1-38), As(V) 8.1 (0.3-120), MMA(V) 0.8 (0.1-6.0), and DMA(V) 0.4 (0.1-3.9). Saliva arsenic correlated with drinking water arsenic. Odds ratios for skin lesions increased with saliva arsenic concentrations. The association between saliva arsenic concentrations and the prevalence of skin lesions was statistically significant (P &lt;0.001).<br /><br /><strong>CONCLUSIONS: </strong>Speciation of As(V), As(III), MMA(V), and DMA(V) in human saliva is a useful method for monitoring arsenic exposure.",
Arsenic,1378386,"Sodium Arsenite Decreases Proliferation In PHA-Stimulated Lymphocytes, By Inhibiting Interleukin-2 Expression And Secretion Abstract: Evidence from human and animal models have shown that arsenic (As) induces suppression of T lymphocytes. We have previously shown that sodium arsenite inhibited phytohemagglutinin (PHA)-induced proliferation in murine T lymphocytes (Goytia-Acevedo et al., 2003) probably by a mechanism mediated by high intracellular Ca++ [Ca++]i level. On the other hand, it has been shown that sodium arsenite reduces secretion of IL-2 in human lymphocytes and the expression of its receptor (Yu et al., 1998); however the effect of arsenite on IL-2 gene transcription has not been evaluated. Thus, we evaluated, the effect of sodium arsenite on IL-2 mRNA expression by RT-PCR, and IL-2 secretion by ELISA in PHA-stimulated spleen T lymphocytes obtained from female C57BL/6 mice. T lymphocyte activation was measured through CD69 expression by cytofluorometry, and ERK1/2 phosphorylation was determined by immunoblotting. Sodium arsenite (1 and 10 uM) significantly inhibited IL-2 mRNA expression and IL-2 secretion in a concentration- dependent manner in PHA-stimulated lymphocytes (24 h). Interestingly, in PHA-stimulated lymphocytes (4 h), sodium arsenite (1 and 10 uM) significantly inhibited (75%) CD69 expression. These results were in agreement with our previous data showing that sodium arsenite (1 and 10 uM) inhibited PHA-induced ERK1/2 phosphorylation in a concentration dependent manner (Conde-Moo et al., 2003). Our results suggest that sodium arsenite modulate IL-2 gene expression probably by interfering with ERK1/2 signaling, and this may be related, at least partially, to the inhibition of PHA-induced proliferation of T lymphocytes. Further research on the relationships between As-induced [Ca++]i imbalance and the ability of As to modulate IL-2 gene expression is needed. This work was partially supported by the Mexican Council for Science and Technologhy",
Arsenic,627487,"Effects of glutamine on adhesion molecule expression and leukocyte transmigration in endothelial cells exposed to arsenic Abstract: This study evaluated whether glutamine (GLN) concentration was related to endothelial surface molecule expression and the migration of polymorphonuclear neutrophils (PMNs) through endothelial cells (ECs) stimulated by arsenic. Human umbilical vein endothelial cells (HUVECs) and PMNs were treated with different GLN concentrations (0, 300, 600 and 1000 microM) for 24 h. After that, we stimulated HUVECs for 3 h with 0.5 microM arsenic, and PMNs were allowed to transmigrate to ECs for 2 h. HUVEC surface expressions of cell adhesion molecules and integrin (CD11b) and interleukin (IL)-8 receptor expressions on PMNs were measured. The transendothelial migration of PMNs was also analyzed. The results showed that cell adhesion molecule (CAM) and integrin expressions in arsenic groups were higher than in those without arsenic. Among the arsenic groups, the expression of CAMs on ECs and CD11b, and IL-8 receptor on PMNs was lowest with 0 microM compared with the other GLN concentrations. Vascular CAM-1 on ECs and CD11b on PMN expression were higher with 300 microM than with 600 and 1000 microM GLN. IL-8 secretions from ECs and PMNs were higher with 300 muM than with 600 and 1000 microM GLN, and this was consistent with the expression of the IL-8 receptor on PMNs. Polymorphonuclear neutrophil transmigration was significantly higher with 300 muM GLN than with other GLN concentrations. These results suggest that ECs and PMNs were activated after arsenic stimulation. Cell adhesion molecule expressions on ECs and PMNs were suppressed in the absence of GLN. A low GLN concentration comparable to catabolic conditions resulted in higher adhesion molecule expression and greater transendothelial migration of neutrophils. Glutamine administration at levels similar to or higher than physiological concentrations reduced IL-8 and adhesion molecule expression; PMN transmigration was also decreased after stimulation with arsenic.",
Arsenic,2278773,"A report on the prevalence of depression and anxiety in patients with frozen shoulder and their relations to disease status Abstract: Musculoskeletal diseases often have concomitant psychological disorders, such as depression and anxiety. Frozen shoulder (FS) is a musculoskeletal disease, and causes pain and stiffness in the shoulder. The relationship between FS and psychological disorders has rarely been investigated. This cross-sectional study was to evaluate the risk of depression and anxiety in patients with primary FS, and to explore the relationship between psychological disorders and disease status. In this study, anxiety and depression were evaluated in 124 patients (78 women and 46 men) with primary FS, compared with 130 (72 women and 58 men) age-, sex- and education matched healthy controls between March 2009 and June 2012. Simple shoulder test (SST); shoulder pain and disability index (SPADI); the range of motion (ROM); visual analog scales (VAS) for pain and sleep disturbances; hospital anxiety and depression scale for depression (HADS-D) and for anxiety (HADS-A); and health assessment questionnaire (HAQ) were used to assess clinical and psychological status. In FS patients, the prevalence of depression and anxiety was 28.2 and 24.2%, respectively. Compared with the healthy controls, higher HADS-D (6.41?±?3.69, 5. 23?±?2.87 p?=?0.006) and HADS-A (6.16?±?3.62, 4.90?±?3.05 p?=?0.003) were detected. The FS patients with depression or anxiety had significantly lower SST and HAQ scores, significantly higher VAS and SPADI scores and significantly higher prevalence of sleep disturbances compared with the FS patients with normal psychological status. The correlations of SST, SPADI, VAS and sleep disturbances but not ROM with HADS-A and HADS-D were significant (?p?&lt;?0.05). This finding indicates that anxiety and depression may coexist with FS; patients with psychological disorders have more severe self-reported shoulder pain and functional restriction.",
Arsenic,710905,"Effect of arsenic exposure during pregnancy on infant development at 7 months in rural Matlab, Bangladesh Abstract: Exposure to arsenic-contaminated drinking water during pregnancy is associated with low birth weight and fetal loss, and there is concern that the infants' development may be affected.<br /><br /> We assessed the effects of in utero arsenic exposure during pregnancy on infants' problem-solving ability and motor development.<br /><br /> We conducted a large population-based study of nutritional supplementation with 4,436 pregnant women in Matlab, Bangladesh, an area of high-arsenic-contaminated tube wells. We measured arsenic concentration in spot urine specimens at 8 and 30 weeks of pregnancy. We assessed a subsample of 1,799 infants, born to these mothers, at 7 months of age on two problem-solving tests (PSTs), the motor scale of the Bayley Scales of Infant Development-II, and behavior ratings.<br /><br /> Arsenic concentrations in maternal urine were high, with a median (interquartile range) of 81 microg/L (37-207 microg/L) at 8 weeks of gestation and of 84 microg/L (42-230 microg/L) at 30 weeks. Arsenic exposure was related to many poor socioeconomic conditions that also correlated with child development measures. Multiple regressions of children's motor and PST scores and behavior ratings, controlling for socioeconomic background variables, age, and sex, showed no significant effect of urinary arsenic concentration on any developmental outcome.<br /><br /> We detected no significant effect of arsenic exposure during pregnancy on infant development. However, it is possible that other effects are as yet unmeasured or that effects will become apparent at a later age.",
Arsenic,1017778,"Reduced cellular redox status induces 4-hydroxynonenal-mediated caspase 3 activation leading to erythrocyte death during chronic arsenic exposure in rats Abstract: Chronic exposure to arsenic in rats led to gradual accumulation of the toxicant in erythrocytes causing oxidative stress in these cells. 4-Hydroxynonenal (4-HNE), a major aldehyde product of lipid peroxidation, contributed significantly to the cytopathological events observed during oxidative stress in the erythrocytes of exposed rats. 4-HNE triggered death signal cascade that was initiated with the formation of HNE-protein adducts in cytosol. HNE-protein adduct formation resulted in depletion of cytosolic antioxidants followed by increased generation of ROS. Results showed accumulation of hydrogen peroxide (H(2)O(2)) from the early stages of arsenic exposure, while superoxide (O(2)(*-)) and hydroxyl radical ((*)OH) also contributed to the oxidative stress during longer period of exposure. Suppression of antioxidant system coupled with increased generation of ROS eventually led to activation of caspase 3 during arsenic exposure. Attenuation of HNE-mediated activation of caspase 3 in presence of N-acetylcysteine (NAC) indicated the involvement of GSH in the process. Prevention of HNE-mediated degradation of membrane proteins in presence of Z-DEVD-FMK identified caspase 3 as the principal mediator of HNE-induced cellular damage during arsenic exposure. Degradation of band 3 followed by its aggregation on the red cell surface promoted immunologic recognition of redistributed band 3 by autologous IgG with subsequent attachment of C3b. Finally, the formation of C3b-IgG-band 3 immune complex accelerated the elimination of affected cells from circulation and led to the decline of erythrocyte life span during chronic arsenic toxicity.",1
Arsenic,1019147,"Effects of arsenite on central monoamines and plasmatic levels of adrenocorticotropic hormone (ACTH) in mice Abstract: We studied the effects of chronic arsenic exposure on brain monoamines and plasma levels of adrenocorticotropic hormone (ACTH) of mice. After weaning, mice received arsenic (0, 20, 40, 60 or 100 ppm) in drinking water over a period of 9 weeks. Monoamine content was quantified in different brain regions, arsenic was quantified in brain tissue and ACTH levels in plasma. Brain arsenic concentrations up to 200 ng/g showed a significant correlation with exposure levels and produced slight modifications in regional monoamine levels. ACTH plasma levels were significantly associated with norepinephrine (NE) concentrations in the medulla and pons, but not with hypothalamic NE levels. ACTH levels were significantly higher in the group exposed to 20 ppm. Dopamine showed significant dose-related decreases in the hypothalamus. These results show that chronic sodium arsenite exposure produces changes in central monoamines, which are not associated on a dose-dependent basis with major alterations in plasma ACTH.",
Arsenic,1372992,"Differential effects of various trivalent ad pentavalent organic and inorganic arsenic species on glucose metabolism in isolated kidney cells Abstract: BIOSIS COPYRIGHT: BIOL ABS. We have compared the acute toxicities of the trivalent arsenic species arsenite, oxophenylarsine (PhAsO), 2-chlorovinyloxoarsine (ClvinAsO), methyloxoarsine (MeAsO), and of the pentavalent arsenic species arsenate, methyl- and phenylarsonic acid in rat kidney tubules (RKT) and Madin-Darby canine kidney (MDCK) cells. In RKT, PhAsO (1 mumol l-1, 60 min) almost completely (>90%) blocked gluconeogenesis without affecting cell viability as assessed by dye exclusion. In MDCK cells, PhAsO (2 mumol l-1) markedly inhibited glucose uptake (60% of controls) within 30 min, while cell viability, as assessed by formazan formation, was not affected within 180 min. MeAsO and ClvinAsO were similarly effective to PhAsO in both RKT and MDCK cells. Estimated IC50 values for the inhibition of gluconeogenesis were 0.55 (PhAsO), 0.69 (ClvinAsO) and 0.99 mumol l-1 (MeAsO) and for the inhibition of glucose uptake 1.23 (PhAsO), 2.62 (ClvinAsO) and 6.99 mumol l-1 (MeAsO). At longer storage tim",
Arsenic,627578,"Persistent neuropathy and hyperkeratosis from distant arsenic exposure Abstract: The purpose of this case series is to assess long-term sequelae of arsenic exposure in a cohort acutely exposed to arsenic in drinking water from a well dug into a landfill containing arsenical pesticides. Ten of the 13 individuals (or next of kin) in the initial study agreed to participate in the follow-up study. Next of kin provided questionnaire data and released medical information on the three individuals who had died. The remaining seven cohort members were assessed by an interview, questionnaire, detailed physical examination and sensory nerve testing. Available medical records were obtained and reviewed. Sensory testing was performed using an automated electrodiagnostic sensory Nerve Conduction Threshold (sNCT) evaluation. Sensory complaints and electrodiagnostic findings consistent with polyneuropathy were found in a minority (3/7) of subjects 28 years after an acute toxic arsenic exposure. Two of the seven patients examined (1 of 3 with neuropathic findings) also had hyperkeratotic lesions consistent with arsenic toxicity and one of the patients had hyperpigmentation on their lower extremities possibly consistent with arsenic toxicity.",
Arsenic,628680,"Sodium arsenite-induced stress-related gene expression in normal human epidermal, HaCaT, and HEL30 keratinocytes Abstract: Arsenic is a carcinogen that poses a significant health risk in humans. Based on evidence that arsenic has differential effects on human, rodent, normal, and transformed cells, these studies addressed the relative merits of using normal human epidermal keratinocytes (NHEK) and immortalized human (HaCaT) and mouse (HEL30) keratinocytes when examining stress-induced gene expression that may contribute to carcinogenesis. We hypothesize that redox-related gene expression is differentially modulated by arsenic in normal versus immortalized keratinocytes. To test the hypothesis, we exposed keratinocytes to sodium arsenite for 4 or 24 hr, at which time serine threonine kinase-25 (stk25) and nicotine adenine dinucleotide phosphate [nad(p)h] quinone oxidoreductase gene expression were measured. The effect of glutathione reduction on arsenite-induced cytotoxicity and gene expression in NHEK also was evaluated by addition of l-buthionine-[S,R]-sulfoximine (BSO) to culture media. Results indicate the term LC(50) for arsenite is approximately 10-15 microM in NHEK and HEL30 keratinocytes and 30 microM in HaCaT keratinocytes. Compared with HaCaT and HEL30 keratinocytes, a nontoxic concentration of arsenite (2.5 microM) increases stk25 and nad(p)h quinone oxidoreductase gene expression in NHEK, an effect partially attenuated by BSO. These data indicate that NHEK and HaCaT/HEL30 keratinocytes have similar sensitivities toward arsenite-induced cytotoxicity but unique gene expression responses. They also suggest that arsenite modulates gene expression in NHEK involved in cellular signaling and other aspects of intermediary metabolism that may contribute to the carcinogenic process.",
Arsenic,1348151,SCREENING TECHNIQUES FOR DETERMINATION OF ARSENIC Abstract: HEEP COPYRIGHT: BIOL ABS.,
Arsenic,1330747,"Thioredoxin-related Protein 32 is an arsenite-regulated Thiol Reductase of the proteasome 19 S particle Abstract: Perturbation of the cytoplasmic protein folding environment by exposure to oxidative stress-inducing As(III)-containing compounds challenges the ubiquitin-proteasome system. Here we report on mass spectrometric analysis of As(III)-induced changes in the proteasome's composition in samples prepared by stable isotope labeling with amino acids in cell culture, using mammalian cells in which TRP32 (thioredoxin-related protein of 32 kDa; also referred to as TXNL1) was identified as a novel subunit of the 26 S proteasome. Quantitative genetic interaction mapping, using the epistatic miniarray profiling approach, identified a functional connection between TRP32 and the proteasome. Deletion of txl1, the Schizosaccharomyces pombe homolog of TRP32, results in a slow growth phenotype when combined with deletion of cut8, a gene required for normal proteasome localization. Deletion analysis in vivo, chemical cross-linking, and manipulation of the ATP concentration in vitro during proteasome immunopurification revealed that the C-terminal domain of mammalian TRP32 binds the 19 S regulatory particle in proximity to the proteasome substrate binding site. Thiol modification with polyethylene glycol-maleimide showed disulfide bond formation at the active site of TRP32 in cells exposed to As(III). Pulse-chase labeling showed that TRP32 is a stable protein whose half-life of &gt;6 h is surprisingly reduced to 1 h upon exposure of cells to As(III). These findings reveal a previously undescribed thiol reductase at the proteasome's regulatory particle.",
Arsenic,2064209,"Differential in vitro bioaccessibility of residual As in a field-aged former smelter site and its implication for potential risk Abstract: Chemical forms of arsenic (As) present in a former smelter site were determined. A five-step sequential extraction showed that about 94.8 to 99.2% of total As concentration was found to be present as residual form, and interestingly some of the residual As seemed to be still bioaccessible, when determined with an in vitro bioaccessibility test. However, the extents of bioaccessible As greatly varied among the three soils tested. Soil B showed the highest bioaccessibility being 17.18mg-As/kg (11.9%) followed by 12.71 (2.02%) and 14.03mg-As/kg (0.64%) in soils C and A, respectively. When the residual As was treated with hydrofluoric acid (i.e., HF) 65.3 to 80.9mg-As/kg was extracted and only 4.17 to 7.25% of the HF-extractable As was found to be bioaccessible. In contrast, when the residual As was treated with hydroperchloric acid (i.e., HClO4) only 5.64 to 8.01mg-As/kg was recovered but 64.5 to 92.5% of the HClO4-extractable As was bioaccessible. The results suggest the presence of differential bioaccessibility of residual As, which apparently depends on the solid phase that As is associated with (i.e., organic matter or clay minerals). Of the As present as residual fraction, the As mainly bound to silicate mineral showed extremely low bioaccessibility and the As associated with refractory organic matter was highly bioaccessible.",
Arsenic,744880,"Arsenite and monomethyl arsonous acid-induced toxicity in human urothelial cells Abstract: Arsenic is a known bladder carcinogen. However, the mechanism of arsenic-induced bladder injury or carcinogenesis is unknown. Studies investigating gene expression caused by arsenite [As(III)] and monomethylarsonous acid [MMA(III)] exposure in human urothelial (UROtsa) cells revealed the presence of both oxidative stress and protein damage. These results prompted the study of reactive oxygen species generation in As(III) and MMA(III)-induced cytotoxicity in UROtsa cells. Reduction of intracellular glutathione levels via administration of buthionine S-Rsulfoximine (25 ?M) increased cytotoxicity of MMA(III) and As(III) by 4 and 7 fold, respectively, indicating the critical role of cellular antioxidant status. However, concurrent treatment of UROtsa cells with radical scavengers [DPPD (10 ?M and 100 ?M) and DMSO (0.1% and 0.5%)] only ameliorated the cytotoxicity of higher concentrations of As(III) and MMA(III). Thus efforts to block the production of As(III) and MMA(III)-induced reactive oxygen species via adenoviral-mediated infection of both superoxide dismutase and catalase are underway. In addition, to demonstrate that As(III) and MMA(III) produce reactive oxygen species and induce oxidative DNA damage, the fluorescent probe CM-H2DCFDA is being used to detect oxyradical production using confocal microscopy and increases in 8-hydroxy- 2-deoxyguanosine (8-OHdG) are being detected via HPLC to illustrate oxidative DNA damage. These studies will improve the understanding of the role reactive oxygen species play in As(III) and MMA(III) toxicity in a target organ cell line.",
Arsenic,628700,"Arsenic exposure, urinary arsenic speciation, and peripheral vascular disease in Blackfoot disease-hyperendemic villages in Taiwan Abstract: Long-term exposure to ingested inorganic arsenic is associated with peripheral vascular disease (PVD) in the blackfoot disease (BFD)-hyperendemic area in Taiwan. This study further examined the interaction between arsenic exposure and urinary arsenic speciation on the risk of PVD. A total of 479 (220 men and 259 women) adults residing in the BFD-hyperendemic area were studied. Doppler ultrasound was used to diagnose PVD. Arsenic exposure was estimated by an index of cumulative arsenic exposure (CAE). Urinary levels of total arsenic, inorganic arsenite (AsIII) and arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) were determined. Primary methylation index [PMI = MMAV/(AsIII + AsV)] and secondary methylation index (SMI = DMAV/MMAV) were calculated. The association between PVD and urinary arsenic parameters was evaluated with consideration of the interaction with CAE and the confounding effects of age, sex, body mass index, total cholesterol, triglycerides, cigarette smoking, and alcohol consumption. Results showed that aging was associated with a diminishing capacity to methylate inorganic arsenic and women possessed a more efficient arsenic methylation capacity than men did. PVD risk increased with a higher CAE and a lower capacity to methylate arsenic to DMAV. The multivariate-adjusted odds ratios for CAE of 0, 0.1–15.4, and >15.4 mg/L × year were 1.00, 3.41 (0.74–15.78), and 4.62 (0.96–22.21), respectively (P < 0.05, trend test); and for PMI ? 1.77 and SMI > 6.93, PMI > 1.77 and SMI > 6.93, PMI > 1.77 and SMI ? 6.93, and PMI ? 1.77 and SMI ? 6.93 were 1.00, 2.93 (0.90–9.52), 2.85 (1.05–7.73), and 3.60 (1.12–11.56), respectively (P < 0.05, trend test). It was concluded that individuals with a higher arsenic exposure and a lower capacity to methylate inorganic arsenic to DMAV have a higher risk of developing PVD in the BFD-hyperendemic area in Taiwan.",
Arsenic,1508647,"Optimized design and synthesis of a cell-permeable biarsenical cyanine probe for imaging tagged cytosolic bacterial proteins Abstract: To optimize cellular delivery and specific labeling of tagged cytosolic proteins by biarsenical fluorescent probes built around a cyanine dye (Cy3) scaffold, we have systematically varied the polarity of the N-alkyl chain (i.e., 4-5 methylene groups appended by a sulfonate or methoxy ester moiety) and arsenic capping reagent (ethanedithiol versus benzenedithiol). Optimal live-cell labeling and visualization of tagged cytosolic proteins is reported using an ethanedithiol capping reagent with the uncharged methoxy ester functionalized N-alkyl chains. These measurements demonstrate the general utility of this new class of photostable and highly fluorescent biarsenical probes based on the cyanine dye scaffold for in vivo labeling of tagged cellular proteins for live cell imaging measurements of protein dynamics.",
Arsenic,2278911,"Dietary arsenic exposure with low level of arsenic in drinking water and biomarker: A study in West Bengal Abstract: The authors investigated association of arsenic intake through water and diet and arsenic level in urine in people living in arsenic endemic region in West Bengal supplied with arsenic-safe water (&lt;50 ?g L(-1)). Out of 94 (Group-1A) study participants using water with arsenic level &lt;50 ?g L(-1), 72 participants (Group-1B) were taking water with arsenic level &lt;10 ?g L(-1). Multiple regressions analysis conducted on the Group-1A participants showed that daily arsenic dose from water and diet were found to be significantly positively associated with urinary arsenic level. However, daily arsenic dose from diet was found to be significantly positively associated with urinary arsenic level in Group-1B participants only, but no significant association was found with arsenic dose from water in this group. In a separate analysis, out of 68 participants with arsenic exposure through diet only, urinary arsenic concentration was found to correlate positively (r = 0.573) with dietary arsenic in 45 participants with skin lesion while this correlation was insignificant (r = 0.007) in 23 participants without skin lesion. Our study suggested that dietary arsenic intake was a potential pathway of arsenic exposure even where arsenic intake through water was reduced significantly in arsenic endemic region in West Bengal. Observation of variation in urinary arsenic excretion in arsenic-exposed subjects with and without skin lesion needed further study.",
Arsenic,1021573,"Genetic and epigenetic effects of environmental arsenicals Abstract: Environmental arsenic compounds and their methylated metabolites do not form adducts with DNA, but do cause oxidative DNA damage. Chromosome aberrations are seen at toxic concentrations. Genetic effects that occur at non-toxic concentrations include aneuploidy, comutagenesis (resulting from indirect effects on DNA repair), and delayed mutagenesis (probably secondary to aneuploidy and/or epigenetic effects). Effects of trivalent arsenicals on poly(ADP ribose) polymerase and P53 activation may mediate effects on DNA repair and aneuploidy. A growing literature points to the epigenetic effects of arsenic compounds in cells and in vivo. A review of the current literature on DNA methylation, histone modifications and microRNA effects is presented.",
Arsenic,1348516,"Suppression of multidrug resistance via inhibition of heat shock factor by quercetin in MDR cells Abstract: MDR1 promoter has been shown to contain heat shock elements (HSE), and it has been reported that FM3A/M and P388/M MDR cells show a constitutively activated heat shock factor (HSF), suggesting that HSF might be an important target for reversing the multidrug resistance. Therefore, it was examined whether quercetin, which has been shown to interfere with the formation of the complex between HSE and HSF, and to downregulate the level of HSF1, can sensitize MDR cells against anticancer drugs by inhibition of HSF DNA-binding activity. In this study, quercetin appeared to inhibit the constitutive HSF DNA-binding activity and the sodium arsenite-induced HSF DNA-binding activity in the MDR cells. The basal and sodium arsenite-induced MDRCAT activities were remarkably suppressed by the treatment of quercetin. These results were well consistent with the finding that the treatment of quercetin decreased the expression level of P-gp, MDR1 gene product, in dose-dependent manner, and markedly increased the sensitivity of MDR cells to vincristine or vinblastine. These results suggest that quercetin can decrease the expression of P-gp via inhibition of HSF DNA-binding activity, and might be useful as a chemosensitizer in MDR cells.",
Arsenic,736148,"Risk assessment of low-level cadmium and arsenic on the kidney Abstract: Cadmium (Cd) and arsenic (As) are widely distributed in the environment and are known human carcinogens. Several studies reported that chronic exposure to Cd and As produced renal injuries in humans. As one of the mechanisms, oxidative stress was suggested to play a role in the early process of Cd- and/or As-induced tubular damage in the kidney. This study was performed to evaluate the significance of urinary biomarkers, role of oxidative stress, and effect of coexposure to environmental low-level exposure to Cd and/or As in the general population. Urine samples were collected from 290 adults (86 males and 204 females). Urinary concentrations of Cd and As were measured, and kidney biomarkers of toxicity such as beta(2)-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) activity determined in urine. Urinary malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured as oxidative stress indices. The mean concentration of Cd was 1.21 microg/L, 0.84 microg/g creatinine, and As was 5.7 microg/L, 3.95 microg/g creatinine in urine. NAG, MDA, and 8-OHdG were positively correlated with both Cd and As in urine. Positive correlations were also observed between NAG and oxidative indices. The effects of coexposure to Cd and As on biomarkers are more pronounced than for exposure to each metal alone. These findings suggest that chronic exposure to low levels of Cd and/or As might produce tubular damage in the kidney through oxidative stress in humans.",
Arsenic,1346169,EFFECTS OF ARSENIC ON MITOCHONDRIAL AND MICROSOMAL OXIDATIVE INTERACTIONS Abstract: HEEP COPYRIGHT: BIOL ABS. ABSTRACT RAT AMINOPYRINE DEMETHYLASE MIXED FUNCTION OXIDASE NAD DEPENDENT MITOCHONDRIAL DEHYDROGENASE,1
Arsenic,628428,"Deficiency in Ikkbeta gene enhances arsenic-induced gadd45alpha expression Abstract: Chronic arsenic exposure is implicated in the pathophysiology of various human diseases, including cancer and diabetes. Using Ikk? gene knockout mouse embryonic fibroblast cells (Ikk??/?), in the present study we demonstrated that NF-?B inhibition due to Ikk? deficiency up-regulated basal and arsenic-induced expression of gadd45?. In addition to gadd45?, the basal expression of other gadd family members including gadd45?, gadd45? and gadd153 was substantially increased in Ikk??/? cells. Ikk? deficiency prevented the induction of gadd45? and gadd45? by arsenic, whereas the induction of gadd45? and gadd153 was appreciably enhanced in Ikk??/? cells. Furthermore, a substantial decrease in the expression of c-myc, an established endogenous transcriptional repressor of gadd45? and gadd153 genes, was noted. Thus, these results uncover the molecular mechanism by which NF-?B signalling contributes to the regulation of gadd family gene expression induced by arsenic.",
Arsenic,1015709,"Low-Level Environmental Cadmium Exposure is Associated with DNA Hypomethylation in Argentinean Women Abstract: Background: Cadmium, a common food pollutant, alters DNA methylation in vitro. Epigenetic effects might therefore partly explain cadmium's toxicity, including carcinogenicity, but human data on epigenetic effects are lacking. Objectives: To evaluate effects of dietary cadmium exposure on DNA methylation, considering other environmental exposures, genetic predisposition, and gene expression. Methods: Concentrations of cadmium, arsenic, selenium and zinc in blood and urine of nonsmoking women (N=202) from the Northern Argentinean Andes were measured by ICP-MS. Methylation in CpG islands of LINE1 (proxy for global DNA methylation) and promoter regions of p16 (CDKN2A) and MLH1 in peripheral blood were measured by bisulfite PCR pyrosequencing. Genotyping (N=172) for DNMT1 (rs10854076, rs2228611) and DNMT3B (rs2424913, rs2424932) was performed with SequenomTM; and gene expression (N=90) with DirectHyb HumanHT-12 v3.0. Results: Cadmium exposure was low: median concentrations in blood and urine were 0.36 and 0.23 µg/L, respectively. Urinary cadmium (ln transformed) was inversely associated with LINE1 methylation (?=-0.50, p=0.0070; ?=-0.44, p=0.026 adjusted for age and coca chewing), but not with p16 or MLH1 methylation. Both DNMT1 rs10854076 and DNMT1 rs2228611 polymorphisms modified associations between urinary cadmium and LINE1 (p-values for interaction in adjusted models were 0.045 and 0.064, respectively). The rare genotypes demonstrated stronger hypomethylation with increasing urinary cadmium concentrations. Cadmium was inversely associated with DNMT3B (rs -0.28, p=0.0086), but not with DNMT1 expression (rs -0.075, p=0.48). Conclusion: Environmental cadmium exposure was associated with DNA hypomethylation in peripheral blood and DNMT1 genotypes modified this association. The role of epigenetic modifications in cadmium-associated diseases needs clarification.",
Arsenic,2298682,"Involvement of the Acr3 and DctA antiporters in Arsenite Oxidation in Agrobacterium tumefaciens 5A Abstract: Microbial arsenite (AsIII) oxidation forms a critical piece of the arsenic cycle in nature, though our understanding of how and why microorganisms oxidize AsIII remains rudimentary. Our model organism Agrobacterium tumefaciens 5A contains two distinct ars operons (ars1 and ars2) that are similar in their coding region content. The ars1 operon is located nearby the aio operon that is essential for AsIII oxidation. The AsIII/H(+) antiporters encoded by acr3-1 and acr3-2 are required for maximal AsIII and antimonite (SbIII) resistance, but acr3-1 (negatively regulated by ArsR-1) appears more active in this regard and also required for AsIII oxidation and expression of aioBA. A malate:phosphate antiporter DctA is regulated by RpoN and AsIII, and is required for normal growth with malate as a sole carbon source. Qualitatively, a ?dctA mutant was normal for AsIII oxidation and AsIII/SbIII resistance at metalloid concentrations inhibitory to the ?acr3-1 mutant; however, aioBA induction kinetics was significantly phase-shift delayed. Acr3 involvement in AsIII/SbIII resistance is reasonably well understood, but the role of Acr3 and DctA antiporters in AsIII oxidation and its regulation is unexpected, and suggests that controlled AsIII trafficking across the cytoplasmic membrane is important to a process understood to occur in the periplasm.",
Arsenic,732011,"Indirect effects of Bax and Bak initiate the mitochondrial alterations that lead to cytochrome c release during arsenic trioxide-induced apoptosis Abstract: Arsenic trioxide is a potent chemotherapeutic agent by virtue of its ability to selectively trigger apoptosis in tumor cells. Previous studies have demonstrated that arsenicals cause direct damage to mitochondria, but it is not clear that these effects initiate apoptosis. Here we used Bak-/- mouse liver mitochondria and virally immortalized Bax-/- Bak-/- mouse embryonic fibroblasts (MEFs) to investigate whether or not multidomain proapoptotic BCL-2 family proteins were required for arsenic-induced mitochondrial damage and cell death. At clinically achievable concentrations, arsenic stimulated cytochrome c release and apoptosis via a Bax/Bak-dependent mechanism. At higher concentrations (125 microM-1 mM), cells died via a Bax/Bak-independent mechanism mediated by oxidative stress that resulted in necrosis. Consistent with previous reports, arsenic directly inhibited complex I of the mitochondrial electron transport chain, which resulted in mitochondrial permeability transition (MPT), accompanying generation of reactive oxygen species (ROS), and thiol oxidation. However, these effects only occurred at concentrations of arsenic trioxide of 50 microM and higher, and the oxidative stress associated with these effects blocked caspase activation. Our data demonstrate for the first time that the cytochrome c release which initiates apoptosis in cells exposed to this classic mitochondrial poison occurs indirectly via the activation of Bax/Bak rather than via direct mitochondrial damage. Furthermore, the results implicate reactive oxygen species in a concentration-dependent mechanistic switch between apoptosis and necrosis.",
Arsenic,504133,"Exposure to metals through the consumption of fish and seafood by the population living near the Ebro River in Catalonia, Spain: Health risks Abstract: The health risks due to metal exposure from consuming various fish and seafood species were assessed for the Catalan population living near the Ebro River (Spain). The concentrations of arsenic, cadmium, chromium, copper, mercury, manganese, nickel, and lead were determined in samples of mussel, clam, hake, sole, cuttlefish, sardine, and anchovy randomly acquired in various localities of the zone under evaluation. In general terms, metal concentrations were similar or lower than the levels recently reported in the literature. The current dietary intake of metals is analogous to that recently estimated for the non-exposed population of Catalonia. Metal exposure through fish and seafood consumption would only mean a slight increase of noncarcinogenic and carcinogenic risk for arsenic, whereas the remaining elements showed risk values below the corresponding threshold levels.",
Arsenic,2278365,"Changes in the level of proteins, free amino acids and protease activities of Clarias batrachus in response to sodium meta-arsenite intoxication Abstract: Increased hazard of arsenic toxicity at many provinces of India causing extensive contamination of their wetlands. To illustrate the consequences of the arsenic menace on the aquatic fauna, a nutritionally important freshwater catfish Clarias batrachus (Linn.) was subjected to the stress of sublethal concentration (1mg/L; 5% of 96-h LC50 value) of sodium meta-arsenite. The alterations induced by the arsenic salt on certain biomolecules (proteins, free amino acids (FAA), and protease activities) in five tissue components (muscle, liver, brain skin, and gills) of the fish using biochemical techniques were estimated. Significant (p&lt;0.01) decrease in the concentration of proteins in all the tissues (19.74-44.84% in muscles; 3.17-49.39% in liver; 10.05-36.16% in brain; 12.62-52.01% in skin and 7.34-61.69% in gills), and significant (p&lt;0.01) increase in FAA (6.84-269.89% in muscles; 125.89-358.03% in liver; 1.07-152.90% in brain; 29.31-401.62% in skin and 38.53-165.07% in gills), and protease activities (43.59-183.33% in muscles; 19.52-131.90% in liver; 8.85-46.72% in brain; 33.33-261.53% in skin and 25.39-50.79% in gills) of the exposed fish were observed. This increase in amino acids and enzyme activity point out toward breakdown of protein leading to their depletion.",
Arsenic,1019806,"Low concentrations of arsenic induce vascular endothelial growth factor and nitric oxide release and stimulate angiogenesis in vitro Abstract: Arsenic (As) is widely distributed in nature, and its contamination in drinking water remains a major public health problem. Exposure to As may lead to degenerative peripheral vascular diseases. The purpose of this study is to clarify the role of As in modulating cell proliferation and in vitro angiogenesis in human umbilical vein endothelial cells (HUVECs) and to scrutinize the contributing factors of these events. The results revealed that lower concentrations (up to 1 microM) of sodium arsenite stimulated HUVEC cell growth. An in vitro angiogenesis assay indicated that low concentrations of As increased vascular tubular formation, which was abrogated by hemoglobin, a potent nitric oxide scavenger. In contrast, higher concentrations of As (&gt;5 micro M) revealed cytotoxicity and inhibition to angiogenesis. We also demonstrated that lower concentrations of As upregulated the expression of constitutive nitric oxide synthase (NOS3) at both transcriptional and translational levels and that lower concentrations of As implicated a modulatory role in vascular endothelial growth factor (VEGF) expression. In addition, low concentrations of As (&lt;1 micro M) increased von Willebrand Factor (vWF) antigen expression, whose elevation paralleled the onset of angiogenesis and was considered an early indicator of endothelial activation in tumor metastasis. VEGF and basic fibroblast growth factor can synergistically upregulate the vWF gene expression. Therefore, we conclude that the treatment of HUVECs with As leads to cell proliferation and activation, which preferentially enhances angiogenesis in vitro, possibly via the VEGF-NOS signaling pathway. The molecular mechanism(s) by which As facilitates angiogenesis remains to be elucidated.",
Arsenic,627033,"Oxidative stress reveals heterogeneity of FMRP granules in PC12 cell neurites Abstract: PC12 cells are a well-known model of parasympathetic neurons. They have also been used to study the dynamics of heterologously expressed fragile X mental retardation (FMRP) granule trafficking down neurites. Here, we demonstrate that undifferentiated and differentiated PC12 cells harbor endogenous FMRP-containing granules. These granules are not stress granules because they do not associate with an authentic stress granule marker protein T-cell internal antigen 1 (TIA-1). Treatment with sodium arsenite induces stress granule formation in undifferentiated and differentiated PC12 cells. In NGF-treated cells, FMRP-containing stress granules are observed in the soma, neurites and growth cones by co-immunostaining with anti-TIA-1 antibody. These data demonstrate that all three microdomains respond similarly to oxidative stress. Nevertheless, we find significantly less co-localization of FMRP and TIA-1 and FMRP and its homologs in the neurites of differentiated PC12 cells treated with sodium arsenite than in the soma or growth cones. The heterogeneity of these granules suggests that FMRP has multiple roles in neurites.",
Arsenic,1366275,"Application of ICP-MS to arsenic determination in solid samples containing silica Abstract: BIOSIS COPYRIGHT: BIOL ABS. Different sorbents mixed with sand are being tested for the retention of arsenic compounds in flue gases from coal combustion and gasification processes. In order to control the efficiency and the retention capacities of these sorbents and to evaluate the likely emissions into the environment, the determination of arsenic content must be carried out after the sorption. In this work, a methodology was developed for sample preparation and arsenic determination in samples with high levels of silica generation AAS method and tested on a standard reference material, with reproducible and accurate results.",
Arsenic,1797850,"Dietary arsenic consumption and urine arsenic in an endemic population: response to improvement of drinking water quality in a 2-year consecutive study Abstract: We assessed the association between arsenic intake through water and diet, and arsenic levels in first morning-void urine under variable conditions of water contamination. This was done in a 2-year consecutive study in an endemic population. Exposure of arsenic through water and diet was assessed for participants using arsenic-contaminated water (?50 ?g L(-1)) in a first year (group I) and for participants using water lower in arsenic (<50 ?g L(-1)) in the next year (group II). Participants with and without arsenical skin lesions were considered in the statistical analysis. Median dose of arsenic intake through drinking water in groups I and II males was 7.44 and 0.85 ?g kg body wt.(-1) day(-1) (p <0.0001). In females, it was 5.3 and 0.63 ?g kg body wt.(-1) day(-1) (p <0.0001) for groups I and II, respectively. Arsenic dose through diet was 3.3 and 2.6 ?g kg body wt.(-1) day(-1) (p?=?0.088) in males and 2.6 and 1.9 ?g kg body wt.(-1) day(-1) (p?=?0.0081) in females. Median arsenic levels in urine of groups I and II males were 124 and 61 ?g L(-1) (p?=?0.052) and in females 130 and 52 ?g L(-1) (p?=?0.0001), respectively. When arsenic levels in the water were reduced to below 50 ?g L(-1) (Indian permissible limit), total arsenic intake and arsenic intake through the water significantly decreased, but arsenic uptake through the diet was found to be not significantly affected. Moreover, it was found that drinking water mainly contributed to variations in urine arsenic concentrations. However, differences between male and female participants also indicate that not only arsenic uptake, but also many physiological factors affect arsenic behavior in the body and its excretion. As total median arsenic exposure still often exceeded 3.0 ?g kg body wt.(-1) day(-1) (the permissible lower limit established by the Joint Expert Committee on Food Additives) after installation of the drinking water filters, it can be concluded that supplying the filtered water only may not be sufficient to minimize arsenic availability for an already endemic population.",
Arsenic,1240225,"Arsenic induces apoptosis in myoblasts through a reactive oxygen species-induced endoplasmic reticulum stress and mitochondrial dysfunction pathway Abstract: A pool of myoblasts available for myogenesis is important for skeletal muscle size. The decreased number of skeletal muscle fibers could be due to the decreased myoblast proliferation or cytotoxicity. Identification of toxicants that regulate myoblast apoptosis is important in skeletal muscle development or regeneration. Here, we investigate the cytotoxic effect and its possible mechanisms of arsenic trioxide (As(2)O(3)) on myoblasts. C2C12 myoblasts underwent apoptosis in response to As(2)O(3) (1-10 ?M), accompanied by increased Bax/Bcl-2 ratio, decreased mitochondria membrane potential, increased cytochrome c release, increased caspase-3/-9 activity, and increased poly (ADP-ribose) polymerase (PARP) cleavage. Moreover, As(2)O(3) triggered the endoplasmic reticulum (ER) stress indentified through several key molecules of the unfolded protein response, including glucose-regulated protein (GRP)-78, GRP-94, PERK, eIF2?, ATF6, and caspase-12. Pretreatment with antioxidant N-acetylcysteine (NAC, 0.5 mM) dramatically suppressed the increases in reactive oxygen species (ROS), lipid peroxidation, ER stress, caspase cascade activity, and apoptosis in As(2)O(3) (10 ?M)-treated myoblasts. Furthermore, As(2)O(3) (10 ?M) effectively decreased the phosphorylation of Akt, which could be reversed by NAC. Over-expression of constitutive activation of Akt (c.a. Akt) also significantly attenuated As(2)O(3)-induced myoblast apoptosis. Taken together, these results suggest that As(2)O(3) may exert its cytotoxicity on myoblasts by inducing apoptosis through a ROS-induced mitochondrial dysfunction, ER stress, and Akt inactivation signaling pathway.",
Arsenic,1508633,"Metagenomic exploration reveals high levels of microbial arsenic metabolism genes in activated sludge and coastal sediments Abstract: Arsenic contamination in a water system is an urgent environmental problem that has caused severe endemic arsenicosis in south and southeast Asian countries. It is well known that microbially mediated arsenic metabolism can enhance arsenic mobility, bioavailability, and toxicity. Here, for the first time, we applied the Illumina high-throughput metagenomic and metatranscriptomic approaches to study the distribution, diversity, abundance, and expression of microbial arsenic metabolism genes in activated sludge and five coastal sediments. An average depth of ~2.6 Gb clean data for each sample was finally obtained for BLAST analysis after quality filtration and normalization. The results revealed that: (1) highly diverse arsenic metabolism-like genes were found and the overall abundance varied from 0.18 % to 0.26 % in the six metagenomic data sets; (2) arsenic metabolism-like genes were expressed with extremely low levels or no expression at all in activated sludge; and (3) the distribution, diversity, and abundance of aioA-like, arrA-like, arsB-like, ACR3-like, and arsM-like genes varied significantly in the six surveyed environments. This study provided a novel perspective on understanding the ecology of arsenic metabolism in different water environments using high-throughput sequencing technique.",
Arsenic,1070407,"Decreased metal accumulation in passerines as a result of reduced emissions Abstract: Technological advances in industrial processes have resulted in reduced atmospheric emissions from metal industries all over the globe, but the response of the environment is not well known. The authors studied metal (As, Cd, Cu, Ni, Pb, and Se) accumulation in passerine birds (pied flycatcher, Ficedula hypoleuca, and great tit, Parus major) following almost 20 years of reduced metal emissions from the largest nonferrous smelter in Finland. Close to the industry, emission reductions resulted in reduced exposure to several of the elements and, more importantly, reduced accumulation by 58 to 95% in liver tissue. Albeit showing significant tissue reductions, nestlings had elevated concentrations of arsenic, cadmium, lead, and selenium close to the industry. Single-element concentrations were below critical levels associated with subclinical effects, but the mixture of toxic elements indirectly affected health and reproduction. Our study indicates that in environments with moderate duration of industrial activity, impact, and soil pollution, metal accumulation in organisms can decrease relatively rapidly when atmospheric emissions are reduced.",
Arsenic,1021978,"Dietary Intake of Metals by the Population of Tarragona County (Catalonia, Spain): Results from a Duplicate Diet Study Abstract: The daily intakes of arsenic (As), beryllium, cadmium (Cd), cobalt, chromium, copper, mercury (Hg), manganese, nickel, lead (Pb), antimony, tin, thallium, uranium, vanadium, and zinc by an adult population living in Tarragona County (Catalonia, Spain) were determined by the duplicate diet method with a 10-day sampling period. Duplicate diet samples, prepared as per consumption, were collected during September 2010 in 20 restaurants offering a variety of daily menus (breakfast, lunch, and dinner). A total of 200 composite samples, corresponding to 600 individual samples, were prepared for trace elements analyses, which were carried out by inductively coupled plasma mass spectrometry. The results were compared with data from previous total diet studies (TDS) recently performed in the same geographical area. Notable differences in the intake of the toxic elements As, Cd, Hg, and Pb were found depending on the method used. It is concluded that both the duplicate diet method and the TDS may provide important and useful information to estimate human exposure to metals through the diet and their derived health risks. However, for comparison between surveys or for establishing temporal trends in the intake of metals, it seems to be recommendable to use always the same method. Notwithstanding, if the interest is only to know whether the intake of a certain element is below the tolerable intake, both methods are useful.",
Arsenic,1572527,Quality control of arsenic determination in drinking water with ICP-MS: Krakow Tap Survey 2010 Abstract: ,
Arsenic,1508712,"Exposure Assessment of Organochlorine Pesticides, Arsenic, and Lead in Children From the Major Agricultural Areas in Sonora, Mexico Abstract: There is a lack of information of exposure to organochlorine pesticides (OCP) and some metals, such as lead (Pb) and arsenic (As), both of which were used as arsenicals pesticides, in children living in the major agricultural areas of Mexico. The objective of this study was to assess the exposure of children to different OCP, As, and Pb in the Yaqui and Mayo valleys of Sonora to generate population baseline levels of these toxins. A cross-sectional study was undertaken in 165 children (age 6-12 years old) from 10 communities from both valleys during 2009. Blood samples were analyzed for OCP and Pb and first morning void urine for inorganic As (InAs). All of the blood samples had detectable levels of dichlorodiphenyltrichloroethylene (p,p'-DDE) ranging from 0.25 to 10.3 ?g/L. However lindane, dichlorodiphenyltrichloroethane (p,p'-DDT), aldrin, and endosulfan were detected in far less of the population (36.4, 23.6, 9.1, and 3 %, respectively). Methoxychlor and endrin were not found in any sample. The average value of Pb in this population was 3.2 ?g Pb/dL (range 0.17-9.0) with 8.5 % of the samples having levels &lt;5.0 ?g Pb/dL. Urinary As levels ranged from 5.4 to 199 ?g As/L with an average value of 31.0 ?g As/L. Levels &gt; 50 ?g/L were observed in 12.7 % of the samples. Our results show that is important to start a risk-reduction program to decrease exposure to these toxins in Mexican communities. In addition, the results can be used to establish the baseline levels of exposure to these toxins in this agricultural region and may be used as a reference point for regulatory agencies.",
Arsenic,1022562,"Global alteration of gene expression in human keratinocytes by inorganic arsenic Abstract: Alteration of gene expression by inorganic arsenic has been studied in cultured human keratinocytes derived from normal epidermis, a premalignant lesion and a malignant tumor. The purpose was to find whether these cells displayed common alterations in gene expression that might elucidate the mechanism of arsenic action. Global analysis of approximately 12 000 genes by microarray showed that approximately 30% were expressed. Of these, transcription of a substantial fraction (up to 12%) was altered, nearly twice as many being suppressed as stimulated by 2-fold or more at 2 micro M sodium arsenite or 6 micro M arsenate, which did not affect cell growth. At 0.67 micro M arsenite (50 p.p.b.), effects on transcription were less pronounced but clearly evident. Genes whose transcription was altered in common among all the treated keratinocytes included those induced by reactive oxygen, of which heme oxygenase-1 displayed the highest fold induction. Genes indicative of reactive oxygen generation were detected at the earliest time examined, raising the possibility this feature drives subsequent cellular responses. Unlike some agents that produced transient induction of heme oxygenase-1, arsenicals produced sustained induction. Comparison with other agents producing reactive oxygen in the cells, as reflected in heme oxygenase-1 induction, suggested cellular differentiation was suppressed by sustained but not transient generation of reactive oxygen. Sustained global changes in gene expression were seen in target cells treated chronically with inorganic arsenic at concentrations consumed by millions of humans in contaminated drinking water.",
Arsenic,711019,"A prospective study of body mass index and mortality in Bangladesh Abstract: Body mass index (BMI) (kg/m(2)) has a U- or J-shaped relationship with all-cause mortality in Western and East Asian populations. However, this relationship is not well characterized in Bangladesh, where the BMI distribution is shifted towards lower values.<br /><br /> Using data on 11,445 individuals (aged 18-75 years) participating in the Health Effects of Arsenic Longitudinal Study (HEALS) in Araihazar, Bangladesh, we prospectively examined associations of BMI (measured at baseline) with all-cause mortality during approximately 6 years of follow-up. We also examined this relationship within strata of key covariates (sex, age, smoking, education and arsenic exposure). Cox proportional hazards models adjusted for these covariates and BMI-related illnesses were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for BMI categories defined by the World Health Organization.<br /><br /> Low BMI was strongly associated with increased mortality in this cohort (P-trend < 0.0001). Severe underweight (BMI < 16 kg/m(2); HR 2.06, CI 1.53-2.77) and moderate underweight (16.0-16.9 kg/m(2); HR 1.39, CI 1.01-2.90) were associated with increased all-cause mortality compared with normal BMI (18.6-22.9 kg/m(2)). The highest BMI category (> or =23.0 kg/m(2)) did not show a clear association with mortality (HR 1.10, CI 0.77-1.53). The BMI-mortality association was stronger among individuals with <5 years of formal education (interaction P = 0.02).<br /><br /> Underweight (presumably due to malnutrition) is a major determinant of mortality in the rural Bangladeshi population.",
Arsenic,2088566,"Histopathology predicts clinical outcome in advanced epithelial ovarian cancer patients treated with neoadjuvant chemotherapy and debulking surgery Abstract: <strong>OBJECTIVE: </strong>To analyze the factors prognostic of survival in patients with advanced epithelial ovarian cancer (EOC) treated with neoadjuvant chemotherapy (NAC) followed by interval debulking surgery.<br /><br /><strong>METHODS: </strong>Outcomes were retrospectively in patients with advanced EOC or peritoneal cancer who received neoadjuvant paclitaxel and carboplatin chemotherapy every 3weeks for three to four cycles, followed by interval debulking surgery and three additional cycles of the same regimens from January 2001 to November 2010. Therapeutic response was assessed histopathologically as grade 0 to 3, based on the degree of disappearance of cancer cells, displacement by necrotic and fibrotic tissue, and tumor-induced inflammation. Factors prognostic of progression-free survival (PFS) and overall survival (OS) were calculated.<br /><br /><strong>RESULTS: </strong>The 124 enrolled patients had a median age of 62years (range, 35-79years). Viable cancer cells were observed in specimens resected from 72 patients (58%) at interval debulking surgery after NAC. Multivariate analysis using the Cox proportional hazard model showed that advanced (stage IV) disease (hazard ratio [HR]=1.94, p=0.003), residual cancer at the end of surgery ?1cm (HR=3.78, p&lt;0.001), and histological grade 0-1 (HR=1.65, p=0.03) were independent predictors of decreased OS. Grade 0-1 was also an independent predictor of increased risk of relapse within 6months (odds ratio=8.42, p=0.003).<br /><br /><strong>CONCLUSIONS: </strong>Residual disease of ?1cm, advanced stage, and the presence of more viable disease in resected specimens are prognostic factors for survival in advanced EOC patients receiving NAC followed by interval debulking surgery.",
Arsenic,1020257,"Arsenic induces oxidative stress and activates stress gene expressions in cultured lung epithelial cells Abstract: Chronic exposure to low levels of arsenic can cause lung cancer. However, the cellular and molecular mechanisms for lung cell transformation in response to arsenic are not known. These studies investigated the hypothesis that low levels of arsenic increase intracellular oxidant levels, promote production of mitogenic transcription factors and antioxidant enzymes. Initially, arsenic decreased GSH cellular level and rapidly increased to 280% of GSH level in nonexposed lung cells in 24 h. Buthionine sulfoximine (BSO) potentiated the arsenic toxicity of lung epithelial cells (LEC). Exposure of LEC to 5 microM arsenite cause time-dependent increase in gamma-glutamylcysteine synthetase (gamma-GCS) expression. Our data demonstrated that arsenic induced the heavy subunit of gamma-GCS (gamma-GCS-HS) mRNA levels as early as 4 h as compared to the control level. It significantly increased (sixfolds) gamma-GCS-HS mRNA expression after 8 h of treatment. The activation of AP-1 transcription factors may also play a regulatory role in this process. Significant elevations in c-fos and c-jun mRNA levels were observed within 30 min after exposure to arsenic and by enhancement of AP-1 DNA binding activity and transactivation activity. Responsiveness of LEC to oxidative stress caused by arsenic exposure was further evaluated with mobility shift assay involving redox-sensitive transcription factor NF-kappa B. The specificity of binding was verified by an antibody-supershift. The NF-kappa B DNA binding activities increased more than twofold 30 min after exposure to arsenic and returned to control levels after 4 h of treatment. It remains to be determined whether NF-kappa B plays a role in the As-induced apoptosis or alternatively in attempting to protect the cells from As-induced cell death by upregulating the expression of resistance factors.",
Arsenic,2278053,"Xenophilus arseniciresistens sp. nov., an arsenite-resistant bacterium isolated from soil Abstract: A Gram-negative, aerobic, motile, rod-shaped, arsenite [As(III)]-resistant bacterium, designated as strain YW8T, was isolated from agricultural soil. The 16S rDNA sequence analysis showed over 97 % sequence similarity to strains of the environmental species Xenophilus azovorans, Xenophilus aerolatus, Simplicispira metamorpha, Variovorax soli, and Xylophilus ampelinus. However, the phylogenetic tree indicated that strain YW8T formed a separate clade from Xenophilus azovorans. DNA-DNA hybridization experiments showed that the DNA-DNA relatedness values between strain YW8T and its closest phylogenetic neighbours were below 24.2-35.5 %, which clearly separated the strain from these closely related species. The major cellular fatty acids were C16:0, C 17:0 cyclo, C18:1 ?7c, and Summed feature 3(C16:1 ?6c and/or C16:1 ?7c). The genomic DNA G+C content was 69.3 mol%, and the major respiratory quinone was ubiquinone-8. The predominant polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), unknown phospholipid 1 (PL1), unknown phospholipid 2 (PL2), unknown phospholipid 3 (PL3), unknown polar Lipid (L) and phosphatidylserine (PS). The major polyamine were 2-hydroxyputrescine and putrescine. On the basis of morphological and physiological/biochemical characteristics, phylogenetic position, DNA-DNA hybridization, and chemotaxonomic data, this strain was considered to represent a novel species of the genus Xenophilus, for which the name Xenophilus arseniciresistens sp. nov. was proposed; the type strain is YW8T (=CCTCC AB 2012103T=KACC 16853T).",
Arsenic,2337095,"Enhanced cadmium resistance and accumulation in Pseudomonas putida KT2440 expressing the phytochelatin synthase gene of Schizosaccharomyces pombe Abstract: Phytochelatins (PCs) are cysteine-rich peptides with high binding affinity for toxic metals. Expressing the PC synthase gene (PCS) in plant growth-promoting bacteria may enhance its metal resistance and accumulation, consequently increasing phytoremediation efficiency in heavy metal pollution. In this study, PCS from Schizosaccharomyces pombe was cloned and expressed in Pseudomonas putida KT2440, which was confirmed by real-time RT-PCR through an increase in SpPCS mRNA expression level when induced by 20 mu mol of CdCl2 in the transformed Ps.putida cells. The recombined strain KT2440-SpPCS exhibited enhanced Cd, Ag and Hg resistance. Compared with the original strain, KT2440-SpPCS also displayed a threefold to fivefold increase in Cd accumulation (14 center dot 32 mu mol g(-1) to 17 center dot 38 mu mol g(-1); dry weight) when grown in 30 and 50 mu mol CdCl2, along with an increase in nonprotein thiols. Further experiments showed significantly enhanced germination rates and growth of wheat seeds in 0 center dot 1mmol to 1 center dot 0mmol Cd when inoculated with KT2440-SpPCS. This study shows potential use of Ps.putida KT2440-SpPCS in plants to construct a symbiotic system for an enhanced phytoremediation of heavy metal-contaminated environments. <br> <br>Significance and Impact of the Study <br> <br>The symbiotic system of using plant growth-promoting bacteria Pseudomonas putida to express phytochelatin synthase gene of Schizosaccharomyces pombe together in plants resulted in high heavy metal resistance and high accumulation capacity, suggesting potential enhancement in phytoremediation of heavy metal-contaminated environments.",
Arsenic,1025503,"Co-administration of monoisoamyl dimercaptosuccinic acid and Moringa oleifera seed powder protects arsenic-induced oxidative stress and metal distribution in mice Abstract: Arsenic contamination of groundwater in the West Bengal basin in India is unfolding as one of the worst natural geo-environmental disasters to date. Chelation therapy with chelating agents is considered to be the best known treatment against arsenic poisoning; however, they are compromised with certain serious drawbacks/side-effects. Efficacy of combined administration of Moringa oleifera (M. oleifera) (English: Drumstick tree) seed powder, a herbal extract, with a thiol chelator monoisoamyl DMSA (MiADMSA) post-arsenic exposure in mice was studied. Mice were exposed to 100 ppm arsenic in drinking water for 6 months, followed by 10-days treatment with M. oleifera seed powder (500 mg/kg, orally through gastric gavage, once daily), MiADMSA (50 mg/kg, intraperitoneally, once daily) either individually or in combination. Arsenic exposure caused significant decrease in blood glutathione, delta-aminolevulinic acid dehydratase (ALAD), accompanied by increased production of reactive oxygen species in blood and soft tissues. Significant inhibition of superoxide dismutase, catalase, and glutathione peroxidase activities in tissues (liver in particular) along with significant increase in thiobarbituric acid reactive substances and metallothionein levels in arsenic intoxicated mice was also noted. Combined administration of MiADMSA with M. oleifera proved better than all other treatments in the recovery of most of the above parameters accompanied by more pronounced depletion of arsenic. The results suggest that concomitant administration of M. oleifera during chelation treatment with MiADMSA might be a better treatment option than monotherapy with the thiol chelator in chronic arsenic toxicity.",
Arsenic,1015879,"Content of selenium, total and inorganic arsenic and bioaccessibility of arsenic in children diets of Mexico Abstract: BACKGROUND: The aim of this study was to evaluate the intake of selenium, total and inorganic arsenic and the bioaccessibility of arsenic in diets of Mexican schoolchildren using an in vitro method. RESULTS: Total and inorganic arsenic concentrations in the diets ranged from 0.05 to 1.15 mg kg(-1) dry weight (DW) and from 0.023 to 0.088 mg kg(-1) DW respectively, while selenium levels were between 0.08 and 0.20 mg kg(-1) DW. Daily intake of total and inorganic arsenic ranged from 0.15 to 10.49 µg day(-1) kg(-1) body weight (BW) and from 0.06 to 1.11 µg day(-1) kg(-1) BW respectively, while that of selenium varied from 0.29 to 2.63 µg day(-1) kg(-1) BW. Bioaccessibility of total and inorganic arsenic ranged from 4 to 97% (mean 44 ± 21.5%) and from 33 to 97% (mean 71 ± 22.5%) respectively. CONCLUSION: Inorganic arsenic levels in the diets were low. Therefore there appears to be a low risk of adverse effects resulting from excess inorganic arsenic intake from these diets. Copyright © 2011 Society of Chemical Industry.",
Arsenic,2345790,"Characterization of polycyclic aromatic hydrocarbons degradation and arsenate reduction by a versatile Pseudomonas isolate Abstract: A Pseudomonas isolate, designated PAHAs-1, was found capable of reducing arsenate and degrading polycyclic aromatic hydrocarbons (PAHs) independently and simultaneously. This isolate completely reduced 1.5 mM arsenate within 48 h and removed approximately 100% and 50% of 60 mg l(-1) phenanthrene and 20 mg l-1 pyrene within 60 h, respectively. Using PAHs as the sole carbon source, however, this isolate showed a slow arsenate reduction rate (4.62 mu M h(-1)). The presence of arsenic affected cell growth and concurrent PAHs removal, depending on PAH species and arsenic concentration. Adding sodium lactate to the medium greatly enhanced the arsenate reduction and pyrene metabolism. The presence of the alpha subunit of the aromatic ring-hydroxylating dioxygenase (ARHD) gene, arsenate reductase (arsC) and arsenite transporter (ACR3(2)) genes supported the dual function of the isolate. The finding of latter two genes indicated that PAHAs-1 possibly reduced arsenate via the known detoxification mechanism. Preliminary data from hydroponic experiment showed that PAHAs-1 degraded the majority of phenanthrene (&gt;60%) and enhanced arsenic uptake by Pteris vittata L (from 246.7 to 1187.4 mg kg(-1) As in the fronds). The versatile isolate PAHAs-1 may have potentials in improving the bioremediation of PAHs and arsenic co-contamination using the plant-microbe integrated strategy. (C) 2014 Elsevier Ltd. All rights reserved.",
Arsenic,1519010,"Probing the fractal pattern and organization of Bacillus thuringiensis bacteria colonies growing under different conditions using quantitative spectral light scattering polarimetry Abstract: Development of methods for quantification of cellular association and patterns in growing bacterial colony is of considerable current interest, not only to help understand multicellular behavior of a bacterial species but also to facilitate detection and identification of a bacterial species in a given space and under a given set of condition(s). We have explored quantitative spectral light scattering polarimetry for probing the morphological and structural changes taking place during colony formations of growing Bacillus thuringiensis bacteria under different conditions (in normal nutrient agar representing favorable growth environment, in the presence of 1% glucose as an additional nutrient, and 3 mM sodium arsenate as toxic material). The method is based on the measurement of spectral 3×3 Mueller matrices (which involves linear polarization measurements alone) and its subsequent analysis via polar decomposition to extract the intrinsic polarization parameters. Moreover, the fractal micro-optical parameter, namely, the Hurst exponent H, is determined via fractal-Born approximation-based inverse analysis of the polarization-preserving component of the light scattering spectra. Interesting differences are noted in the derived values for the H parameter and the intrinsic polarization parameters (linear diattenuation d, linear retardance ?, and linear depolarization ? coefficients) of the growing bacterial colonies under different conditions. The bacterial colony growing in presence of 1% glucose exhibit the strongest fractality (lowest value of H), whereas that growing in presence of 3 mM sodium arsenate showed the weakest fractality. Moreover, the values for ? and d parameters are found to be considerably higher for the colony growing in presence of glucose, indicating more structured growth pattern. These findings are corroborated further with optical microscopic studies conducted on the same samples.",
Arsenic,628763,"Is the genotoxic effect of arsenic mediated by oxygen free radicals? Abstract: Previous investigations have shown that trivalent arsenic is inducing chromosomal aberrations and sister chromatid exchanges (SCEs). In a search for the genotoxic mechanism we have studied the effects of the oxygen-radical-scavenging enzymes superoxide dismutase (SOD) and catalase (CAT) on arsenic-induced SCEs in cultured human lymphocytes. The results indicate that SOD and possibly also CAT have a protective effect against arsenic-induced DNA damage. Arsenic, which is emitted in environmental pollutions e.g. from smelters and coal-fired power plants, appears to be underestimated as environmental mutagen and potential synergist to ionizing radiation.",
Arsenic,1015944,"Hepatoprotective and neuroprotective activity of liposomal quercetin in combating chronic arsenic induced oxidative damage in liver and brain of rats Abstract: <strong>CONTEXT: </strong>Arsenic is a naturally occurring toxicant that causes acute and chronic adverse health effects, including cancer.<br /><br /><strong>OBJECTIVE: </strong>The study was performed to evaluate the therapeutic efficacy of liposome entrapped flavonoidal quercetin in combating arsenic toxicity mediated oxidative damage in hepatocytes and brain cells in rat model.<br /><br /><strong>MATERIALS AND METHODS: </strong>Hepatic and neuronal cell damage in rats was made by daily arsenic (6 mg/kg b wt, 9 mg/kg b wt and 12 mg/kg b wt) treatment via oral route for four consecutive months. Liposomal quercetin (2.71 mg QC/kg b. wt) were injected s.c. on rats treated with 12 mg/kg b. wt. NaAsO(2) twice a week for four months.<br /><br /><strong>RESULTS AND DISCUSSION: </strong>Inorganic arsenic deposition was found to be most significant in hepatic (9.32 ± 0.100 µg/g tissue) and neuronal (6.21 ± 0.090 µg/g tissue) cells of rats treated with 12 mg/kg b wt of arsenite. Antioxidant levels in hepatic and neuronal cells were reduced significantly by the induction of arsenic. Liposomal quercetin was found most potent for a complete prevention of arsenite-induced reduction in antioxidant levels in the liver and brain of rats. Arsenic induced a substantial increase in hepatic hydroxyproline (HP) and Liposomal quercetin treatment resulted in complete replenishment of the HP level to normal. Liposomal quercetin completely prevented the arsenite-induced upregulation of cytochrome c expression in liver and brain significantly suggesting that the protective effect of Liposomal quercetin could be related to the reduction of arsenic deposition in both the organs.<br /><br /><strong>CONCLUSION: </strong>Thus, Liposomal quercetin might prove to be of therapeutic potential against arsenite-induced hepatic and neuronal cell damage in rats.",
Arsenic,1020539,"Transactivation of RARE and GRE in the cellular response to arsenic Abstract: Arsenic compounds are a somewhat unique class of metals, which have been considered as both carcinogens and chemotherapeutic agents for cancers. Tumor promotion effects of arsenic are believed to be associated with its transactivational activities on transcription factors, such as AP-1 and NFkappaB, while the induction of cell apoptosis and differentiation by arsenic is considered to be a mechanism for the chemotherapeutic effects of arsenic. Here, we found that exposure of cells to arsenite and arsenate leads to transactivation of retinoic acid response elements (RARE) and glucocorticoid response elements (GRE) in mouse epidermal JB6 cells. These inductions occur in a time-dependent manner. Furthermore, induction of RARE activity by arsenic was synergistically enhanced by co-treatment of cells with retinoic acid, while GRE activation by arsenic was not affected by combined treatment of cells with fluocinolone acetonide (FA). In consideration of the important role of RARE and GRE in induction of cell differentiation, we speculate that transactivation of RARE and GRE by arsenic may be involved in its induction of cell differentiation and anti-cancer activities in addition to its induction of apoptosis.",
Arsenic,1031467,"Induction of cytoplasmic accumulation of p53: A mechanism for low levels of arsenic exposure to predispose cells for malignant transformation Abstract: Although epidemiologic studies have linked arsenic exposure to the development of human cancer, the mechanisms underlying the tumorigenic role of arsenic remain largely undefined. We report here that treatment of cells with sodium arsenite at the concentrations close to environmental exposure is associated with the up-regulation of Hdm2 and the accumulation of p53 in the cytoplasm. Through the mitogen-activated protein kinase pathway, arsenite stimulates the P2 promoter-mediated expression of Hdm2, which then promotes p53 nuclear export. As a consequence, the p53 response to genotoxic stress is compromised, as evidenced by the impaired p53 activation and apoptosis in response to UV irradiation or 5FU treatment. The ability of arsenite to impede p53 activation is further demonstrated by a significantly blunted p53-dependent tissue response to 5FU treatment when mice were fed with arsenite-containing water. Together, our data suggests that arsenic compounds predispose cells to malignant transformation by up-regulation of Hdm2 and subsequent p53 inactivation.",
Arsenic,1794816,The Chemistry of Lucrezia Borgia et al Abstract: ,
Arsenic,1381715,"Topical fluorouracil therapy for precancers and cancers of the skin Abstract: Topical fluorouracil (FU) is an extremely effective agent for treating multiple actinic keratoses. It is also of value in the treatment of Bowen's disease, actinic cheilitis, arsenical keratoses, radiodermatitis, X-ray-induced keratoses, leukoplakia, and the erythroplasia of Queyrat. Topical FU may be successful in the treatment of superficial basal-cell carcinomas, but should not be used for nodular carcinomas of the face or neck except under unusual circumstances and with mandatory histologic follow-up evaluation. The usual method of treatment is twice daily application of a 1 percent FU solution in propylene glycol. Several modifications of various types of commonly employed preparations and the manner in which each is used are described, along with the respective indications. The considerable discomfort associated with the use of topical FU can be lessened by the stepwise approach outlined--a method extraordinarily valuable for older patients. Occasional complications are primary irritant dermatitis and allergic contact dermatitis; these must be recognized promptly and treated, as must other less frequent side effects. Topical FU appears to be of great value in the destruction of existing precancerous skin lesions. When used repeatedly, it may postpone indefinitely the development of significant precancerous and cancerous skin lesions.",
Arsenic,1509334,A Simple and Sensitive Colorimetric Detection of Silver Ions Based on Cationic Polymer-Directed AuNPs Aggregation Abstract: ,
Arsenic,2343518,"The effect of a telephone follow-up intervention on illness perception and lifestyle after myocardial infarction in China: A randomized controlled trial Abstract: <strong>BACKGROUND: </strong>Lifestyle modification is an integral component of cardiac secondary prevention, while it has been confirmed that myocardial infarction (MI) patients' health-related behaviors are heavily influenced by their illness perception.<br /><br /><strong>OBJECTIVES: </strong>To evaluate the effect of a telephone follow-up intervention for improving MI patients' illness perception and lifestyle.<br /><br /><strong>DESIGN: </strong>A randomized controlled trial, longitudinal research design was employed.<br /><br /><strong>SETTINGS: </strong>Cardiac care units in four major general hospitals in Guangzhou, China.<br /><br /><strong>PARTICIPANTS: </strong>Inclusion criteria were being diagnosed with an initial acute MI, being able to communicate orally in Mandarin or Cantonese and read in Chinese, and living in Guangzhou. Exclusion criteria were with continuing uncontrolled arrhythmias or heart failure, being illiteracy, or with a history of major psychiatric illness, exercise-induced asthma, uncontrolled diabetes, or evidence of dementia.<br /><br /><strong>METHOD: </strong>124 patients admitted with the first acute MI were randomized to receive either routine care or routine care plus a telephone follow-up intervention, which consist of a pre-discharge education and three telephone follow-up instructions. Data were collected before discharge, at the 6th and the 12th week after discharge from hospital, respectively.<br /><br /><strong>RESULTS: </strong>At the 6th and the 12th week after discharge, patients in the intervention group had significantly positive perceptions about symptoms of MI (mean difference 3.27, 95% confidence interval 2.48-4.07, p&lt;.001; mean difference 2.12, 95% confidence interval 1.34-2.89, p&lt;.001 respectively) and how long their illness would last (mean difference -0.69, 95% confidence interval -0.91 to -0.47, p&lt;.001; mean difference -0.74, 95% confidence interval -0.96 to -0.51, p&lt;.001 respectively) compared with the control group. The intervention group also had more positive beliefs about the controllability (F=4.23, p=.04) and more improved beliefs about the causes of MI than the control group. Moreover, the intervention improved the patients' nutrition (F=5.16, p=.03) and physical activity at the 12-week follow-up (mean difference 0.37, 95% confidence interval 0.17-0.58, p&lt;.001).<br /><br /><strong>CONCLUSION: </strong>This telephone follow-up intervention can result in improved illness perception and lifestyle after MI. It could be incorporated into current hospital treatment regimens for MI to improve patients' quality of life.",
Arsenic,1936199,"FRACTIONATION AND DISTRIBUTION OF ARSENIC IN DESULFURIZATION GYPSUM, SLAG AND FLY ASH FROM A COAL-FIRED POWER PLANT Abstract: An increasing number of pollution control devices furnished in power plants to reduce air pollution produce large amounts of solid waste. Toxic elements in the solid byproducts pose some new environmental problems. The total amounts and fractions of arsenic in desulfurization gypsum, slag and fly ash from a power plant were investigated using a chemical sequential extraction procedure in this study. The fractions were divided into (1) non-specifically sorbed fraction, (2) specifically-sorbed fraction, (3) amorphous Fe and Al oxide-bound fraction, (4) crystalline Fe and Al oxide-bound fraction, and (5) residual fraction. The arsenic in the various fractions showed different mobilities. The order of the total arsenic contents in the different samples was: fly ash &gt; gypsum &gt; slag. Arsenic was accumulated in fly ash and lost in slag. Transportation of arsenic from the flue to gypsum during the desulfurization process was negligible. The arsenic in fly ash had higher mobility compared with the other samples. The order of the mobility of arsenic was: fly ash &gt; slag &gt; desulfurization gypsum. Our findings indicated that arsenic in fly ash could be leached out readily under natural conditions and pose risks to our environment. The storage of fly ash should be considered carefully to avoid or minimize the possibility of arsenic pollution.",
Arsenic,1331171,"Arsenite down-regulates cytochrome P450 1A1 at the transcriptional and posttranslational levels in human HepG2 cells Abstract: Aryl hydrocarbon receptor (AhR) ligands, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and metals, typified by arsenite (As(III)), are environmental cocontaminants, and their molecular interaction may disrupt the coordinated regulation of the carcinogen activating enzyme cytochrome P450 1A1 (CYP1A1). Therefore, in this study we examined the effects of coexposure to As(III) and TCDD on the expression of CYP1A1 in HepG2 cells. Our results showed that As(III) caused a dose-dependent decrease in TCDD-mediated induction of CYP1A1 mRNA, protein, and catalytic activity levels. As(III) significantly inhibited TCDD-mediated induction of AhR-dependent luciferase reporter gene expression without altering CYP1A1 mRNA stability. In addition, As(III) increased heme oxygenase-1 (HO-1) mRNA, which coincided with a further decrease in the CYP1A1 catalytic activity levels. When a competitive HO-1 inhibitor, tin mesoporphyrin, was applied to HepG2 cells or the cells were transfected with siRNA for HO-1 there was a partial restoration of the inhibition of TCDD-mediated induction of CYP1A1 catalytic activity. Treatment of cells with heme or hemoglobin partially restored the As(III)-mediated inhibition of CYP1A1 catalytic activity. On the other hand, cobalt protoporphyrin increased HO-1 mRNA, with a concomitant decrease in CYP1A1 activity, without affecting CYP1A1 mRNA, which was reversed by HO-1 siRNA transfection. This study demonstrates that As(III) down-regulates CYP1A1 through transcriptional and posttranslational mechanisms. In addition, HO-1 is involved in the As(III)-mediated down-regulation of CYP1A1 at the catalytic activity level.",
Arsenic,1378309,"DMPS-arsenic challenge test: I: Increased urinary excretion of monomethylarsonic acid in humans given dimercaptopropane sulfonate Abstract: BIOSIS COPYRIGHT: BIOL ABS. The purpose of the present study was to evaluate in a novel manner the arsenic exposure of humans living in two towns in Northeastern Chile. Residents of one town drink water containing 593 mug As. Those in the control town drink water containing 21 mug As/I. Our hypothesis was that the administration of the chelating agent, 2,3-dimercaptopropane-1-sulfonic acid, Na salt (DMPS, DIMAVAL) would increase the urinary excretion of arsenic, alter the urinary profile of arsenic species and thus result in a better indication of the body load of arsenic and a better biomarker for arsenic exposure. The method used to evaluate these subjects was to give them 300 mg DMPS by mouth, after an overnight fast, and collect urine at specified time periods. The urine samples were analyzed for inorganic arsenic, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and total arsenic by hydride generation and atomic absorption spectrophotometry. The results indicated that: 1) During the 2",
Arsenic,1018270,"Hepatoprotective role and antioxidant capacity of selenium on arsenic-induced liver injury in rats Abstract: The present study was undertaken to evaluate the protective effect of selenium against arsenic-induced oxidative damage in experimental rats. Males were randomly divided into four groups where the first was served as a control, whereas the remaining groups were respectively treated with sodium selenite (3mg/kg b.w.), sodium arsenite (5.55mg/kg b.w.) and a combination of sodium arsenite and sodium selenite. Changes in liver enzyme activities, thiobarbituric acid reactive substances (TBARS) level, antioxidants and reduced glutathione (GSH) contents were determined after 3 weeks experimental period. Exposure of rats to As caused a significant increase in liver TBARS compared to control, but the co-administration of Se was effective in reducing its level. The activities of glutathione peroxidase (GPx) and glutathione-S-transferase (GST) of As-treated group were found lower compared to the control and the Se-treated group. The co-administration of Se had an additive protective effect on liver enzyme activities compared to As-treated animals. On the other hand, a significant increase in plasmatic activities of AST, ALT and ALP was observed in As-treated group. The latter was also exhibited a decrease in body weight and an increase in liver weight compared to the control. The co-administration of Se has decreased the activities of AST, AST and ALP and improved the antioxidant status as well. Liver histological studies have confirmed the changes observed in biochemical parameters and proved the beneficial role of Se. To conclude, results suggest that As exposure enhanced an oxidative stress by disturbing the tissue antioxidant defense system, but the Se co-administration protected liver tissues against As intoxication probably owing to its antioxidant properties.",
Arsenic,1022120,"Critical windows of exposure for arsenic-associated impairment of cognitive function in pre-school girls and boys: A population-based cohort study Abstract: <strong>BACKGROUND: </strong>Exposure to arsenic through drinking water has been associated with impaired cognitive function in school-aged children in a few cross-sectional studies; however, there is little information on critical windows of exposure.<br /><br /><strong>METHODS: </strong>We conducted a population-based longitudinal study in rural Bangladesh. We assessed the association of arsenic exposure, based on urinary arsenic (U-As; twice during pregnancy and twice in childhood), with the development of about 1700 children at 5 years of age using Wechsler Pre-school and Primary Scale of Intelligence [intelligence quotient (IQ)].<br /><br /><strong>RESULTS: </strong>Median maternal U-As in pregnancy was 80 µg/l (10-90 percentiles: 25-400 µg/l). Children's urine contained 35 (12-155) µg/l and 51 (20-238) µg/l at 1.5 and 5 years, respectively. Using multivariable-adjusted regression analyses, controlling for all potential confounders and loss to follow-up, we found that verbal IQ (VIQ) and full scale IQ (FSIQ) were negatively associated with (log) U-As in girls. The associations were consistent, but somewhat stronger with concurrent arsenic exposure [VIQ: B = -2.4, 95% confidence interval (CI) = -3.8 to -1.1; FSIQ: B = -1.4, 95% CI = -2.7 to -0.1, n = 817), compared with that at 1.5 years (VIQ: B = -0.85, 95% CI = -2.1 to 0.4; FSIQ: B = -0.74, 95% CI = -1.9 to 0.4, n = 902), late gestation (VIQ: B = -1.52, 95% CI = -2.6 to -0.4; FSIQ: B = -1.35, 95% CI = -2.4 to -0.3, n = 874) and early gestation (VIQ: B = -1.23, 95% CI = -2.4 to -0.06; FSIQ: B = -0.92, 95% CI = -2.0 to -0.2, n = 833). In boys, U-As showed consistently low and non-significant associations with all IQ measures. An effect size calculation indicated that 100 µg/l U-As was associated with a decrement of 1-3 points in both VIQ and FSIQ in girls.<br /><br /><strong>CONCLUSION: </strong>We found adverse effects of arsenic exposure on IQ in girls, but not boys, at 5 years of age.",
Arsenic,1936067,"Arsenic-induced cutaneous hyperplastic lesions are associated with the dysregulation of Yap, a Hippo signaling-related protein Abstract: Arsenic exposure in humans causes a number of toxic manifestations in the skin including cutaneous neoplasm. However, the mechanism of these alterations remains elusive. Here, we provide novel observations that arsenic induced Hippo signaling pathway in the murine skin. This pathway plays crucial roles in determining organ size during the embryonic development and if aberrantly activated in adults, contributes to the pathogenesis of epithelial neoplasm. Arsenic treatment enhanced phosphorylation-dependent activation of LATS1 kinase and other Hippo signaling regulatory proteins Sav1 and MOB1. Phospho-LATS kinase is known to catalyze the inactivation of a transcriptional co-activator, Yap. However, in arsenic-treated epidermis, we did not observed its inactivation. Thus, as expected, unphosphorylated-Yap was translocated to the nucleus in arsenic-treated epidermis. Yap by binding to the transcription factors TEADs induces transcription of its target genes. Consistently, an up-regulation of Yap-dependent target genes Cyr61, Gli2, Ankrd1 and Ctgf was observed in the skin of arsenic-treated mice. Phosphorylated Yap is important in regulating tight and adherens junctions through its binding to ?Catenin. We found disruption of these junctions in the arsenic-treated mouse skin despite an increase in ?Catenin. These data provide evidence that arsenic-induced canonical Hippo signaling pathway and Yap-mediated disruption of tight and adherens junctions are independently regulated. These effects together may contribute to the carcinogenic effects of arsenic in the skin.",
Arsenic,1337490,"The effect of cigarette smoke and arsenic exposure on urothelial carcinoma risk is modified by glutathione S-transferase M1 gene null genotype Abstract: Inter-individual variation in the metabolism of xenobiotics, caused by factors such as cigarette smoking or inorganic arsenic exposure, is hypothesized to be a susceptibility factor for urothelial carcinoma (UC). Therefore, our study aimed to evaluate the role of gene-environment interaction in the carcinogenesis of UC. A hospital-based case-control study was conducted. Urinary arsenic profiles were measured using high-performance liquid chromatography-hydride generator-atomic absorption spectrometry. Genotyping was performed using a polymerase chain reaction-restriction fragment length polymorphism technique. Information about cigarette smoking exposure was acquired from a lifestyle questionnaire. Multivariate logistic regression was applied to estimate the UC risk associated with certain risk factors. We found that UC patients had higher urinary levels of total arsenic, higher percentages of inorganic arsenic (InAs%) and monomethylarsonic acid (MMA%) and lower percentages of dimethylarsinic acid (DMA%) compared to controls. Subjects carrying the GSTM1 null genotype had significantly increased UC risk. However, no association was observed between gene polymorphisms of CYP1A1, EPHX1, SULT1A1 and GSTT1 and UC risk after adjustment for age and sex. Significant gene-environment interactions among urinary arsenic profile, cigarette smoking, and GSTM1 wild/null polymorphism and UC risk were observed after adjustment for potential risk factors. Overall, gene-environment interactions simultaneously played an important role in UC carcinogenesis. In the future, large-scale studies should be conducted using tag-SNPs of xenobiotic-metabolism-related enzymes for gene determination.",
Arsenic,1339057,"Novel and unexpected bacterial diversity in an arsenic-rich ecosystem revealed by culture-dependent approaches Abstract: <strong>BACKGROUND: </strong>Acid Mine Drainages (AMDs) are extreme environments characterized by very acid conditions and heavy metal contaminations. In these ecosystems, the bacterial diversity is considered to be low. Previous culture-independent approaches performed in the AMD of Carnoulès (France) confirmed this low species richness. However, very little is known about the cultured bacteria in this ecosystem. The aims of the study were firstly to apply novel culture methods in order to access to the largest cultured bacterial diversity, and secondly to better define the robustness of the community for 3 important functions: As(III) oxidation, cellulose degradation and cobalamine biosynthesis.<br /><br /><strong>RESULTS: </strong>Despite the oligotrophic and acidic conditions found in AMDs, the newly designed media covered a large range of nutrient concentrations and a pH range from 3.5 to 9.8, in order to target also non-acidophilic bacteria. These approaches generated 49 isolates representing 19 genera belonging to 4 different phyla. Importantly, overall diversity gained 16 extra genera never detected in Carnoulès. Among the 19 genera, 3 were previously uncultured, one of them being novel in databases. This strategy increased the overall diversity in the Carnoulès sediment by 70% when compared with previous culture-independent approaches, as specific phylogenetic groups (e.g. the subclass Actinobacteridae or the order Rhizobiales) were only detected by culture. Cobalamin auxotrophy, cellulose degradation and As(III)-oxidation are 3 crucial functions in this ecosystem, and a previous meta- and proteo-genomic work attributed each function to only one taxon. Here, we demonstrate that other members of this community can also assume these functions, thus increasing the overall community robustness.<br /><br /><strong>CONCLUSIONS: </strong>This work highlights that bacterial diversity in AMDs is much higher than previously envisaged, thus pointing out that the AMD system is functionally more robust than expected. The isolated bacteria may be part of the rare biosphere which remained previously undetected due to molecular biases. No matter their current ecological relevance, the exploration of the full diversity remains crucial to decipher the function and dynamic of any community. This work also underlines the importance to associate culture-dependent and -independent approaches to gain an integrative view of the community function.<br /><br /><strong>REVIEWERS: </strong>This paper was reviewed by Sándor Pongor, Eugene V. Koonin and Brett Baker (nominated by Purificacion Lopez-Garcia).",
Arsenic,1023868,"Treatment delay period: the case of arsenicosis in rural Bangladesh Abstract: Arsenic concentrations of tubewell water that exceed acceptable limits poses a serious health problem in Bangladesh. Many Bangladeshis are now suffering from arsenic-related diseases. The objectives of this paper are to examine the extent of delay in seeking medical treatment by victims of arsenic poisoning and to identify factors contributing to this delay. Questionnaire survey successfully administered to 663 victims living in two rural areas of Bangladesh provided the major data source for this study. Analysis of survey data reveal that median delay period was 12 months, but the delay period ranged from 1 month to 18 years. Because of this extremely large range, the mean delay period was about 22 months. The study identified time of identification of symptoms of arsenicosis as the most significant determinant of treatment delay followed by treatment sought from members of mobile medical teams, perceived threat, and level of education. Based on the study findings, it is recommended that the Bangladesh government and NGOs involved in arsenic mitigation and prevention efforts should educate individuals at risk for arsenic poisoning about the benefits of seeking early treatment. This study also recommends to continue to dispatch mobile medical teams to the arsenic-impacted areas.",
Arsenic,2278649,"Chemical safety of cereal-based foods: Risk management considerations Abstract: Cereals are a significant food-source for man and his animals and, as such, are extensively traded on the international market. Given the quantities consumed, even low levels of chemical contamination can have significance both in terms of consumer health and the agri-food economy. In terms of the food-safety aspects of cereals and their products, considerable attention has been paid to the role of chemical contaminants. These can arise both during cultivation and/or when cereals are processed. Contamination can arise as a consequence of natural phenomena (e.g. heavy metals and mycotoxins) or by the direct actions of man himself (e.g. pesticides and food process toxicants). However, even where natural phenomena are the direct cause, the presence of the resulting contaminants can be aggravated or mitigated by agronomic and/or subsequent processing practices. In terms of assuring consumer safety, these issues are being addressed as part of the ongoing development of an international consensus on food-safety in terms of good agricultural and manufacturing practices as well as through the evolution of regulatory limits and codes of practice to achieve them.",
Arsenic,612686,"Oxidative damage induced genotoxic effects in human fibroblasts from Xeroderma Pigmentosum group A patients Abstract: Abstract: Xeroderma Pigmentosum A protein plays a pivotal role in the nucleotide excision repair pathway. Through site-directed binding of rigidly kinked double-stranded DNA, it verifies damaged DNA for subsequent excision and incision. Although Xeroderma Pigmentosum A-deficient cells have shown to be defective in oxidative base-lesion repair, the effects of oxidative assault on such cells have not been fully explored. Therefore, we sought to determine the involvement of Xeroderma Pigmentosum A in oxidative DNA damage-repair by treating primary fibroblasts from a patient suffering from Xeroderma Pigmentosum A with sodium arsenite and hydrogen peroxide. Our results show dose-dependent increase in genotoxicity with little change in cytotoxicity with both arsenite and H2O2 in Xeroderma Pigmentosum A-deficient cells compared to control cells. Xeroderma Pigmentosum A-deficient cells displayed increased susceptibility and reduced repair capacity when subjected to DNA damage induced by oxidative stress. Superarray results of apoptotic genes revealed differential expression of Ã¢Ë†Â¼10 genes between Xeroderma Pigmentosum A-deficient and normal cells following arsenite treatment. Interestingly, we noted that arsenite did not inflict as much damage in the cells compared to H2O2. Lack of functional Xeroderma Pigmentosum A seems to increase the susceptibility of oxidative stress-induced genotoxicity while retaining cell viability posing as a potential cancer risk factor of Xeroderma Pigmentosum A patients. [Copyright 2008 Elsevier] Copyright of International Journal of Biochemistry & Cell Biology is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,4648,"The German Environmental Survey 1990/1992 (GerES II): A representative population study Abstract: The German Environmental Survey (GerES) is a large-scale population study which has repeatedly been carried out in Germany. GerES I was conducted in 1985 / 1986 followed by GerES ITs in 1990/1991 (West Germany) and GerES lib in 1991 / 1992 (East Germany). GerES Ill is currently run in both parts of Germany. The main goal of the surveys is to analyse and document the extent, distribution and determinants of the exposure to environmental pollutants of the German general population. Field work is conducted using a combination of several tools, including questionnaires, interviews, human biomonitoring, and indoor and outdoor environmental samplings. This paper describes the design of GerES II, and gives a general outline of the field work and the analytical procedures used. In GerES Il, about 4000 adults were representatively selected from the German population with regard to age, gender and community size. Approximately 700 children were also included. Arsenic, cadmium, copper, chromium, lead, and mercury were determined in blood, morning urine and/or scalp hair. In addition, samples were taken and analysed to characterise exposure in the domestic environment (indoor air, house dust, drinking water). The contribution to exposure of food was also studied. Exposure to volatile organic compounds (VOCs) was determined by personal sampling.",
Arsenic,1704093,Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents-A cost-benefit analysis Abstract: ,
Arsenic,1244045,"Arsenic pollution and fractionation in sediments and mine waste samples from different mine sites Abstract: A characterization of arsenic pollution and its associations with solid mineral phases in sediments and spoil heap samples from four different abandoned mines in Spain is performed. Three of them were mercury mines located in the same mining district, in the province of Asturias, and the other one, devoted to arsenic mining, is in the province of León. A sequential extraction procedure, especially developed for arsenic, was applied for the study of arsenic partitioning. Very high total arsenic concentrations ranging 300-67,000mg·kg(-1) were found. Arsenic fractionation in each mine is broadly in accordance with the mineralogy of the area and the extent of the mine workings. In almost all the studied samples, arsenic appeared predominantly associated with iron oxyhydroxides, especially in the amorphous form. Sediments from cinnabar roasted piles showed a higher arsenic mobility as a consequence of an intense ore treatment, posing an evident risk of arsenic spread to the surroundings. Samples belonging to waste piles where the mining activity was less intense presented a higher proportion of arsenic associated with structural minerals. Nevertheless, it represents a long-term source of arsenic to the environment.",
Arsenic,2347637,"Sources and contents of air pollution affecting term low birth weight in Los Angeles County, California, 2001–2008 Abstract: <strong>BACKGROUND: </strong>Low birth weight (LBW, &lt;2500g) has been associated with exposure to air pollution, but it is still unclear which sources or components of air pollution might be in play. The association between ultrafine particles and LBW has never been studied.<br /><br /><strong>OBJECTIVES: </strong>To study the relationships between LBW in term born infants and exposure to particles by size fraction, source and chemical composition, and complementary components of air pollution in Los Angeles County (California, USA) over the period 2001-2008.<br /><br /><strong>METHODS: </strong>Birth certificates (n=960,945) were geocoded to maternal residence. Primary particulate matter (PM) concentrations by source and composition were modeled. Measured fine PM, nitrogen dioxide and ozone concentrations were interpolated using empirical Bayesian kriging. Traffic indices were estimated. Associations between LBW and air pollution metrics were examined using generalized additive models, adjusting for maternal age, parity, race/ethnicity, education, neighborhood income, gestational age and infant sex.<br /><br /><strong>RESULTS: </strong>Increased LBW risks were associated with the mass of primary fine and ultrafine PM, with several major sources (especially gasoline, wood burning and commercial meat cooking) of primary PM, and chemical species in primary PM (elemental and organic carbon, potassium, iron, chromium, nickel, and titanium but not lead or arsenic). Increased LBW risks were also associated with total fine PM mass, nitrogen dioxide and local traffic indices (especially within 50m from home), but not with ozone. Stronger associations were observed in infants born to women with low socioeconomic status, chronic hypertension, diabetes and a high body mass index.<br /><br /><strong>CONCLUSIONS: </strong>This study supports previously reported associations between traffic-related pollutants and LBW and suggests other pollution sources and components, including ultrafine particles, as possible risk factors.",
Arsenic,2345816,"Gauging intraurban variability of ambient particulate matter arsenic and other air toxic metals from a network of monitoring sites Abstract: A four site monitoring network was established in the Missouri portion of Metropolitan St. Louis during 2008 to characterize spatiotemporal patterns in PM10 arsenic. Arsenic measured at two urban sites in the City of St. Louis was typically higher than arsenic at two suburban sites. Spatiotemporal variability in arsenic is examined by plotting the Pearson correlation coefficient (PCC) against the coefficient of divergence (COD) for each site-pair to merge the temporal tracking ability of PCC with COD's ability to gauge spatial homogeneity. Arsenic measured across the network is apportioned into a network-wide baseline and site-specific excess concentrations to semi-quantitatively differentiate local-scale emission source contributions from sources exerting influence over larger spatial scales. Comparing measured concentrations at each site against the network-wide baseline concentration using a scattergram of PCC and COD emphasizes the impact of local sources on intraurban variability. Conditional probability function (CPF) plots constructed using site-specific measured arsenic and surface winds identify a broad emission source region towards the east, but mask the bearings of local sources in the urban core. CPF plots using site-specific arsenic in excess of the baseline concentrations provide better resolution of local emission source bearings and are triangulated to identify a likely arsenic emission source zone along the industrialized Mississippi Riverfront. Additional air toxic metals measured in this study (selenium, manganese and lead) are also investigated to examine the efficacy of this methodology to characterize intraurban variability. (C) 2014 Elsevier Ltd. All rights reserved.",
Arsenic,1350769,NONDISPERSIVE AND DISPERSIVE ATOMIC FLUORESCENCE SPECTROMETRY OF ARSENIC BY UTILIZING ARSINE-GENERATION TECHNIQUE Abstract: ,
Arsenic,2337232,"Effect of fluvastatin on 24-week telaprevir-based combination therapy for hepatitis C virus genotype 1b-infected chronic hepatitis C Abstract: OBJECTIVES: The addition of fluvastatin significantly improves sustained virological response (SVR) in pegylated interferon and ribavirin (peg-IFN/RBV) combination therapy for patients infected with the hepatitis C virus. However, the add-on effect on telaprevir-based triple combination therapy remains unknown. The aim of this study was to investigate the effect of fluvastatin on telaprevir-based combination therapy by conducting a prospective, open-label, randomized, controlled trial. PATIENTS AND METHODS: Among 124 genotype 1b-infected chronic hepatitis C patients recruited, 116 eligible patients were allocated randomly to two study arms; they received 12 weeks of telaprevir/peg-IFN/RBV, followed by 12 weeks of peg-IFN/RBV with or without 24 weeks of fluvastatin (fluvastatin group and control group, respectively). Treatment outcomes and adverse effects were compared between the two groups. RESULTS: There were 56 men and 60 women, median age 60 years (range, 28-71 years). Rapid virological response and end of treatment response rates were 87.9% (51/58) and 96.6% (56/58) in the control group and 75.9% (44/58) and 98.3% (57/58) in the fluvastatin group, respectively. SVR rates in the control group and the fluvastatin group were 84.5% (49/58) and 81.0% (47/58), respectively; there was no significant difference (P=0.806). Stratified analysis showed that no factors associated with the SVR rate were found between the two groups. No adverse events were associated with fluvastatin. CONCLUSION: In this trial, administration of fluvastatin with telaprevir/peg-IFN/RBV was a safe combination. However, fluvastatin had no add-on effect on 24-week telaprevir-based combination therapy for chronic hepatitis C genotype 1b-infected patients.",
Arsenic,1508525,"Bioaccessible and non-bioaccessible fractions of soil arsenic Abstract: In order for in vitro methods to become widely accepted as tools that accurately assess soil arsenic (As) exposure through the oral ingestion pathway, a better understanding is needed regarding which fractions of soil As are being measured in the in vitro extraction. The objective of the current study is to (1) identify in vitro bioaccessible (IVBA) and non-IVBA fractions of soil As using sequential extraction; and (2) determine the sorptive phases of soil in non-IVBA As soil fractions. Nineteen soils with a range of soil properties were spiked with 250 mg/kg of sodium arsenate and aged. In vitro bioaccessible As (IVBA As) was then determined using The Ohio State University in vitro gastrointestinal method (OSU-IVG), and soil As was fractionated using sequential extraction into: (F1) non-specifically sorbed; (F2) specifically sorbed; (F3) amorphous and poorly crystalline oxides of Fe and Al; (F4) well-crystallized oxides of Fe and Al and residual As phases. The IVBA As across the 19 soil ranged from 0.36 to 2.75 mmol/kg (12 to 86%) with a mean of 1.26 mmol/kg (42%) in the gastric phase and from 0.39 to 2.80 mmol/kg (13 to 87%) in the intestinal phase with a mean of 1.32 mmol/kg (43%). The results of the sequential extraction showed that IVBA As extracted by the OSU-IVG is the As present in the first two fraction (F1 and F2) of the sequential extraction. In the non-IVBA fractions, highly significant relationships (P &lt; 0.01) exist between F3 As and log transformed F3 Fe (r (2) = 0.74), but not F3 Al. In addition, the gastric extraction dissolves a significant fraction of soil Al, but not soil Fe, therefore As sorbed to Al oxides likely contributed to IVBA As and is accounted for in the F2 fraction of the sequential extraction. In vitro methods that demonstrate the ability to extract the similar soil fractions that occur in vivo across a wide range of soil types and As-contaminant sources is an important criteria for in vitro method validation. Further research that includes soils with multiple As-contaminant sources (mining, pesticide, etc.), soil As fractionation, and in vivo bioavailability is needed in order to determine if F1+F2 are the bioavailable As fractions in soils that vary in total As content and sorbed As species.",
Arsenic,1015942,"Arsenic-induced oxidative stress and its reversibility Abstract: This review summarizes the literature describing the molecular mechanisms of arsenic-induced oxidative stress, its relevant biomarkers, and its relation to various diseases, including preventive and therapeutic strategies. Arsenic alters multiple cellular pathways including expression of growth factors, suppression of cell cycle checkpoint proteins, promotion of and resistance to apoptosis, inhibition of DNA repair, alterations in DNA methylation, decreased immunosurveillance, and increased oxidative stress, by disturbing the pro/antioxidant balance. These alterations play prominent roles in disease manifestation, such as carcinogenicity, genotoxicity, diabetes, cardiovascular and nervous systems disorders. The exact molecular and cellular mechanisms involved in arsenic toxicity are rather unrevealed. Arsenic alters cellular glutathione levels either by utilizing this electron donor for the conversion of pentavalent to trivalent arsenicals or directly binding with it or by oxidizing glutathione via arsenic-induced free radical generation. Arsenic forms oxygen-based radicals (OH(•), O(2)(•-)) under physiological conditions by directly binding with critical thiols. As a carcinogen, it acts through epigenetic mechanisms rather than as a classical mutagen. The carcinogenic potential of arsenic may be attributed to activation of redox-sensitive transcription factors and other signaling pathways involving nuclear factor ?B, activator protein-1, and p53. Modulation of cellular thiols for protection against reactive oxygen species has been used as a therapeutic strategy against arsenic. N-acetylcysteine, ?-lipoic acid, vitamin E, quercetin, and a few herbal extracts show prophylactic activity against the majority of arsenic-mediated injuries in both in vitro and in vivo models. This review also updates the reader on recent advances in chelation therapy and newer therapeutic strategies suggested to treat arsenic-induced oxidative damage.",
Arsenic,711051,"Urinary arsenic species and CKD in a Taiwanese population: a case-control study Abstract: Inorganic arsenic has been linked to decreased kidney function through oxidative damage. Arsenic methylation is believed to be a pathway for arsenic metabolism. Lycopene is an antioxidant that reduces oxidative stress; however, the association between urinary arsenic species, plasma lycopene level, and chronic kidney disease (CKD) has seldom been evaluated.<br /><br /> Case-control study.<br /><br /> 125 patients with CKD and 229 controls were recruited from a hospital-based pool.<br /><br /> Urinary arsenic species and plasma lycopene level.<br /><br /> CKD was defined as estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m(2), calculated by using the Modification of Diet in Renal Disease Study equation. Plasma lycopene was measured by means of high-performance liquid chromatography. Urinary arsenic species, including arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid, were determined by means of high-performance liquid chromatography and hydride generator-atomic absorption spectrometry.<br /><br /> Lycopene level was associated positively with eGFR, and participants with a high serum lycopene level had a significant, inverse association with CKD (odds ratio, 0.41; 95% confidence interval, 0.21 to 0.81). Total arsenic level was associated significantly with CKD in a dose-response relationship, especially in participants with a total arsenic level greater than 20.74 compared with 11.78 microg/g creatinine or less (odds ratio, 4.34; 95% confidence interval, 1.94 to 9.69). Furthermore, participants with a high urinary total arsenic level or participants with a low percentage of dimethylarsinic acid had a positive association with CKD when their plasma lycopene level was low.<br /><br /> Because of the single spot evaluation of plasma antioxidants and urinary arsenic species and the small sample size, statistical significance should be interpreted with caution.<br /><br /> This study shows that high urinary total arsenic or low plasma lycopene level is associated positively with CKD. Results suggest that the capacity for arsenic methylation may be associated with CKD in individuals who ingest low arsenic levels in drinking water and also have a low plasma lycopene level.",
Arsenic,1021586,"Health risk assessment of eight heavy metals in nine varieties of edible vegetable oils consumed in China Abstract: Eight heavy metals, namely Cu, Zn, Fe, Mn, Cd, Ni, Pb and As, in nine varieties of edible vegetable oils collected from China were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and graphite furnace atomic absorption spectrometry (GF-AAS) after microwave digestion. The accuracy of procedure was confirmed by certified reference materials (GBW10018 and GBW08551). The relative standard deviations were found below 10%. The concentrations for copper, zinc, iron, manganese, nickel, lead and arsenic were observed in the range of 0.214-0.875, 0.742-2.56, 16.2-45.3, 0.113-0.556, 0.026-0.075, 0.009-0.018 and 0.009-0.019 ?g g-1, respectively. Cadmium was found to be 2.64-8.43 ?g/kg. In general, iron content was higher than other metals in the investigated edible vegetable oils. Comparing with safety intake levels for these heavy metals recommended by Institute of Medicine of the National Academies (IOM), US Environmental Protection Agency (US EPA) and Joint FAO/WHO Expert Committee on Food Additives (JECFA), the dietary intakes of the eight heavy metals from weekly consumption of 175 g of edible vegetable oils or daily consumption 25 g of edible vegetable oils for a 70 kg individual should pose no risk to human health.",
Arsenic,1936049,"Early life arsenic exposure and acute and long-term responses to influenza a infection in mice Abstract: <strong>BACKGROUND: </strong>Arsenic is a significant global environmental health problem. Exposure to arsenic in early life has been shown to increase the rate of respiratory infections during infancy, reduce childhood lung function and increase the rates of bronchiectasis in early adulthood.<br /><br /><strong>OBJECTIVES: </strong>We aimed to determine if early life exposure to arsenic exacerbates the response to early life influenza infection.<br /><br /><strong>METHODS: </strong>C57BL/6 mice were exposed to arsenic in utero and throughout post-natal life. At 1 week of age a subgroup of mice were infected with influenza A. The acute and long term effects of arsenic exposure on viral clearance, inflammation, lung structure and lung function were assessed.<br /><br /><strong>RESULTS: </strong>Early life arsenic exposure reduced the clearance of and exacerbated the inflammatory response to influenza A, and resulted in acute and long term changes in lung mechanics and airway structure.<br /><br /><strong>CONCLUSIONS: </strong>Increased susceptibility to respiratory infections combined with exaggerated inflammatory responses throughout early life may contribute to the development of bronchiectasis in arsenic exposed populations.",
Arsenic,627813,"Induction of multinucleated cells in V79 Chinese hamster cells exposed to dimethylarsinic acid, a methylated derivative of inorganic arsenics: Mechanism associated with the formation of aberrant mitotic spindles Abstract: Induction of multinucleated cells in V79 Chinese hamster cells exposed to dimethylarsinic acid (DMAA), a methylated derivative of inorganic arsenics, and the mechanism of induction were investigated in terms of cytoskeletal changes. DMAA caused mitotic arrest and concomitant induction of multinucleated cells. Arsenite was less effective than DMAA in causing mitotic arrest and in inducing multinucleated cells. Analysis by videograph and a study of post-mitotic incubation of cells arrested in metaphase by DMAA demonstrated that the cells escaped from metaphase with ameboid behaviour and pseudopodia, but they did not divide into daughter cells, thereby resulting in multinucleated cells. During the post-mitotic incubation in the presence of DMAA, the cells did not proliferate but retained their capacity to synthesize DNA. DMAA caused disappearance of the microtubule network in interphase cells, but did not influence the organization of actin stress fibres. Furthermore, DMAA caused aberrations of mitotic microtubules, such as tripolar or quadripolar spindles and aster-like spindles, in a concentration-dependent manner. These results suggest that DMAA specifically acted on the microtubules and that multinucleated cells appeared when cells with aberrant spindles escaped from metaphase to advance the cell cycle and the nuclear membranes were regenerated.",
Arsenic,187145,"Effects of carcinogenic metals on gene expression Abstract: Six metals and/or their compounds have been recognized as carcinogens: arsenic, beryllium, cadmium, chromium, cobalt and nickel. With the exception of arsenic, the main rote of exposure is inhalation and the main target organ is the lung. Arsenic is exceptional because it also produces tumors of skin and lung after oral uptake. With the exception of hexavalent chromium, carcinogenic metals are weak mutagens, if at all, and their mechanisms of carcinogenicity are still far from clear. A general feature of arsenic, cadmium, cobalt and nickel is their property to enhance the mutagenicity and carcinogenicity of directly acting genotoxic agents. These properties can be interpreted in terms of the ability of these metals to inhibit the repair of damaged DNA. However, because carcinogenic metals cause tumor development in experimental animals even under exclusion of further carcinogens, other mechanisms have to be envisaged, too. Evidence will be discussed that carcinogenic metal compounds alter patterns of gene expression leading to stimulated cell proliferation, either by activation of early genes (proto-oncogenes) or by interference with genes downregulating cell growth. Special reference will be devoted to the effects of cadmium and arsenic on gene expression, which have been studied extensively. Possible implications for occupational safety and health will be discussed.",
Arsenic,734989,"Identification of genes responding to low-dose arsenite using HiCEP Abstract: Chronic ingestion of arsenic in polluted food and water can cause various human disorders including skin and lung cancers. Sensitive biomarkers from human tissue/cells could help to prevent chronic intoxication with low-dose arsenite. Using High-Coverage Expression Profiling (HiCEP), an Amplified Fragment Length Polymorphism (AFLP)-based gene expression profiling technique, we analyzed the expression of approximately 11,000 genes in human lung fibroblasts (HFLIII) and compared the profiles between cells, treated and untreated with 1 muM sodium arsenite (NaAsO(2)). Hundreds of genes appeared upregulated and downregulated more than two-fold, 2 h after the treatment. Marked induction was found (>4.4-fold) in a few genes including HMOX1, INHBA, and ANKRD11. Induction of the HMOX1 was detected with a dose of arsenite at as low as 0.3 muM (0.04 ppm) and reached its maximum at 4 h after the treatment. The arsenite-induced HMOX1 expression was attenuated by the promoted glutathione (GSH) synthesis by N-acetyl-L-cysteine (NAC). However, it was not affected by pretreating the cells with general radical scavengers, consistent with the fact that ionizing radiation at either high-or low-doses has never induced HMOX1 in the same assay system. Thus, induction of HMOX1 gene is highly sensitive and also selective against arsenite in the cells. The present process could provide a useful strategy for exploring biomarkers that might help in assessing the known and unknown risks of any natural and artificial toxic reagents.",
Arsenic,1798805,"Reversal effect of monoisoamyl dimercaptosuccinic acid (MiADMSA) for arsenic and lead induced perturbations in apoptosis and antioxidant enzymes in developing rat brain Abstract: Oxidative stress (OS) has been implicated in the pathophysiology of many neurodegenerative disorders. Several studies have shown that exposure to arsenic (As) and lead (Pb) produces oxidative stress, one of the most noted molecular mechanisms for the neurotoxicity of these metals. In the present study, we examined the effect of combined exposure to these metals (As and Pb) on the activity levels of antioxidant enzymes and apoptotic marker enzymes in brain regions (cerebral cortex, hippocampus and cerebellum) of rats at postnatal day (PND) 21, 28 and 3 months age and compared the toxicity levels with individual metals (As or Pb). Further, we also evaluated the therapeutic efficacy of a chelating agent, monoisoamyl dimercaptosuccinic acid (MiADMSA) against arsenic and lead induced developmental neurotoxicity. Pregnant rats were exposed to sodium meta-arsenite (50ppm) and lead acetate (0.2%) individually, and in combination (As=25ppm+Pb=0.1%) via drinking water throughout perinatal period (GD 6 to PND 21). MiADMSA (50mg/kg, orally through gavage) was given for three consecutive days to the PND 18 pups (i.e., PND 18 to PND 20). Exposure to metal mixture resulted in a significant decrease in the activity levels of antioxidant enzymes such as manganese-superoxide dismutase (Mn-SOD), Cu/Zn superoxide dismutase (Cu/Zn-SOD), catalase (CAT) and glutathione peroxidase (GPx) while the malondialdehyde (MDA) levels and mRNA expression levels of caspase-3 and caspase-9 were significantly increased in all the three brain regions. The observed alterations were greater with exposure to metal mixture than individual metals (As or Pb) and the changes were more prominent at PND 28 and greater in cerebral cortex than hippocampus and cerebellum. Interestingly, chelation therapy with MiADMSA showed significant recovery in antioxidant enzymes, lipid peroxidation and gene expression levels of caspase-3 and caspase-9. From these findings, it can be concluded that combined exposure to As and Pb showed an additive effect on antioxidant enzymes than individual metal exposure and chelation therapy with MiADMSA significantly reversed the As and Pb induced apoptosis and oxidative stress, a major contributing factor to neurotoxicity.",
Arsenic,1015747,"Low-level arsenic exposure, AS3MT gene polymorphism and cardiovascular diseases in rural Texas counties Abstract: Most Americans living in rural areas use groundwater for drinking. Exposure to low-level (around the current U.S. standard 10?g/L) arsenic in drinking water is associated with increased mortality of cardiovascular diseases. The current study was to determine if coronary heart disease, hypertension, and hyperlipidemia were associated with low-level arsenic exposure and AS3MT gene single nucleotide polymorphism (SNP) A35991G (rs10748835) in rural Texas. Subjects (156 men, 343 women, 40-96 years of age with a mean of 61) were residents from rural counties Cochran, Palmer, and Bailey, Texas. Groundwater arsenic concentration at each subject's home was estimated with ArcGIS inverse distance weighted interpolation based on the residential location's distances to surrounding wells with known water arsenic concentrations. The estimated groundwater arsenic concentration ranged from 2.2 to 15.3 (mean 6.2)?g/L in this cohort. Logistic regression analysis showed that coronary heart disease was associated with higher arsenic exposure (p&lt;0.05) and with AS3MT genotype GG vs. AA (p&lt;0.05) after adjustments for age, ethnicity, gender, education, smoking status, alcoholism, and anti-hyperlipidemia medication. Hypertension was associated with higher arsenic exposure, while hyperlipidemia was associated with genotype AG vs. AA of the AS3MT gene (p&lt;0.05). Thus, coronary heart disease and its main risk factors were associated with low-level arsenic exposure, AS3MT polymorphism or both.",
Arsenic,735074,"Carcinogenic effect of arsenate in C57BL/6J/Han mice and its modulation by different dietary selenium status Abstract: In this study, carcinogenic effects of arsenate in female C57BL/6J/Han mice exposed in drinking water to 50, 200 or 500 ?g As/L for 24 months were investigated. All animals were fed low-selenium diet, however half of them were supplemented with sodium selenite in drinking water (200 ?g Se/L) to ensure the normal dietary level of selenium. Glutathione peroxidase activity in erythrocytes and plasma as well as selenium concentration in plasma after 3, 6, 12 and 18 months in satellite groups showed considerable decrease in animals from non-selenium supplemented groups in comparison to supplemented groups. A clear arsenic concentration-dependent increase in the number of malignant lymphoma associated with increase in the risk of death was observed (hazard ratio=0.91, 1.46, and 2.24, for 50, 200 and 500 ?g As/L, respectively). No significant influence of selenium dietary status on arsenic carcinogenicity was shown. A significant association between selenium supplementation status and increased risk of death of the animals from causes other than malignant tumors was found (HR=1.79, p=0.04).",
Arsenic,1021799,"Calcium supplementation modulates arsenic-induced alterations and augments arsenic accumulation in callus cultures of Indian mustard (Brassica juncea (L.) Czern.) Abstract: In the present study, the effect of arsenate (AsV) exposure either alone or in combination with calcium (Ca) was investigated in callus cultures of Brassica juncea (L.) Czern. cv. Pusa Bold grown for a period up to 24 h. The AsV?(250 ?M) + Ca (10 mM) treatment resulted in a significantly higher level of As (464 ?g g(-1) dry weight (DW)) than AsV without Ca (167 ?g g(-1) DW) treatment at 24 h. Furthermore, AsV + Ca-treated calli had a higher percent of AsIII (24-47%) than calli subjected to AsV treatment (12-14%). Despite this, AsV + Ca-treated calli did not show any signs of hydrogen peroxide (H(2)O(2)) accumulation or cell death upon in vivo staining, while AsV-exposed calli had increased H(2)O(2), shrinkage of cytoplasmic contents, and cell death. Thus, AsV treatment induced oxidative stress, which in turn elicited a response of antioxidant enzymes and metabolites as compared with control and AsV + Ca treatment. The positive effects of Ca supplementation were also correlated to an increase in thiolic constituents', viz., cysteine, reduced glutathione, and glutathione reductase in AsV + Ca than in AsV treatment. An analysis of selected signaling related genes, e.g., mitogen-activated protein kinases (MAPK3 and MAPK6) and jasmonate ZIM-domain (JAZ3) suggested that AsV and AsV + Ca followed variable pathways to sense and signal the As stress. In AsV-alone treatment, jasmonate signaling was seemingly activated, while MAPK3 was not involved. In contrast, AsV + Ca treatment appeared to specifically inhibit jasmonate signaling and activate MAPK3. In conclusion, Ca supplementation may hold promise for achieving increased As accumulation in plants without compromising their tolerance.",
Arsenic,1508673,"Use of arsenic-induced palmoplantar hyperkeratosis and skin cancers to predict risk of subsequent internal malignancy Abstract: Hyperpigmentation, hyperkeratoses, and Bowen's disease are hallmarks of chronic arsenic exposure. The association between arsenic-induced skin lesions and subsequent internal cancers is examined by using a community-based prospective study. The cohort was enrolled from an arseniasis-endemic area in southwestern Taiwan, where 2,447 residents participated in skin examinations during the late 1980s. The number of participants diagnosed with hyperpigmentation was 673; with hyperkeratosis, 243; and with skin cancer (Bowen's disease or non-melanoma skin cancer), 378. Newly diagnosed internal cancers were ascertained through linkage with National Cancer Registry profiles. Cox regression was performed to estimate hazard ratios with 95% confidence intervals for potential risk predictors. Compared with participants without skin lesions, patients affected with skin cancers had a significantly increased risk of lung cancer (hazard ratio = 4.64, 95% confidence interval: 2.92, 7.38) and urothelial carcinoma (hazard ratio = 2.02, 95% confidence interval: 1.23, 3.30) after adjustment for potential confounders and cumulative arsenic exposure. Hyperkeratosis is significantly associated with an increased lung cancer risk (hazard ratio = 2.76, 95% confidence interval: 1.35, 5.67). A significant interactive effect on lung cancer risk between hyperkeratosis and cigarette smoking was identified, which suggests that patients with hyperkeratosis who have been exposed to arsenic should cease smoking.",
Arsenic,1017308,"Rapid biotransformation of arsenic by a model protozoan Tetrahymena pyriformis GL-C. [corrected] Abstract: Arsenic biomethylation and biovolatilization are thought to be two important metabolic pathways in aquatic and soil environments. Tetrahymena thermophila is a genus of free-living ciliated protozoan that is widely distributed in freshwater environments around the world. In this study, we studied arsenic accumulation, speciation, efflux, methylation and volatilization in this unicellular eukaryote exposed to various concentrations of arsenate. Our results show that T. thermophila accumulated 187 mg.kg?¹ dry weight of arsenic when exposed to 40 ?M for 48 h, with MMAs(V) (monomethylarsenate) and DMAs(V) (dimethylarsenate) as the dominant species, accounting for 66% of the total arsenic. Meanwhile, arsenate, arsenite, MMAs(V) and DMAs(V) were detected in the culture medium; the last three were released by the cells. The production of volatile arsenic increased with increasing external As(V) concentrations and exposure time. To our knowledge, this is the first study on arsenic metabolism, particularly biomethylation and biovolatilization, in protozoa.",
Arsenic,1021879,"Contrasting controls on arsenic and lead budgets for a degraded peatland catchment in Northern England Abstract: Atmospheric deposition of trace metals and metalloids from anthropogenic sources has led to the contamination of many European peatlands. To assess the fate and behaviour of previously deposited arsenic and lead, we constructed catchment-scale mass budgets for a degraded peatland in Northern England. Our results show a large net export of both lead and arsenic via runoff (282 ± 21.3 gPb ha(-1) y(-1) and 60.4 ± 10.5 gAs ha(-1) y(-1)), but contrasting controls on this release. Suspended particulates account for the majority of lead export, whereas the aqueous phase dominates arsenic export. Lead release is driven by geomorphological processes and is a primary effect of erosion. Arsenic release is driven by the formation of a redox-dynamic zone in the peat associated with water table drawdown, a secondary effect of gully erosion. Degradation of peatland environments by natural and anthropogenic processes has the potential to release the accumulated pool of legacy contaminants to surface waters.",
Arsenic,1797775,"Associations between socioeconomic status and environmental toxicant concentrations in adults in the USA: NHANES 2001-2010 Abstract: Low level chronic exposure to toxicants is associated with a range of adverse health effects. Understanding the various factors that influence the chemical burden of an individual is of critical importance to public health strategies. We investigated the relationships between socioeconomic status (SES) and bio-monitored chemical concentration in five cross-sectional waves of the U.S. National Health and Nutrition Examination Survey (NHANES). We utilised adjusted linear regression models to investigate the association between 179 toxicants and the poverty income ratio (PIR) for five NHANES waves. We then selected a subset of chemicals associated with PIR in 3 or more NHANES waves and investigated potential mediating factors using structural equation modelling. PIR was associated with 18 chemicals in 3 or more NHANES waves. Higher SES individuals had higher burdens of serum and urinary mercury, arsenic, caesium, thallium, perfluorooctanoic acid, perfluorononanoic acid, mono(carboxyoctyl) phthalate and benzophenone-3. Inverse associations were noted between PIR and serum and urinary lead and cadmium, antimony, bisphenol A and three phthalates (mono-benzyl, mono-isobutyl, mono-n-butyl). Key mediators included fish and shellfish consumption for the PIR, mercury, arsenic, thallium and perfluorononanoic acid associations. Sunscreen use was an important mediator in the benzophenone-3/PIR relationship. The association between PIR and cadmium or lead was partially mediated by smoking, occupation and diet. These results provide a comprehensive analysis of exposure patterns as a function of socioeconomic status in US adults, providing important information to guide future public health remediation measures to decrease toxicant and disease burdens within society.",
Arsenic,1070324,"Effect of mercury and arsenic from industrial effluents on the drinking water and comparison of the water quality of polluted and non-polluted areas: A case study of Peshawar and Lower Dir Abstract: The purpose of the present study was to find out the sources of mercury and arsenic pollution of water in the industrial area of Peshawar, the capital of Khyber Pakhtunkhwa, Pakistan. Samples of effluents, mud, and water were collected from the target area (industrial area of Peshawar), the area of water supply source, and from the less polluted area, the Lower Dir district, as the control. Hg was determined by the cold vapor generation technique, while arsenic was determined using the electrothermal atomic absorption technique. Data of the water from the industrial area were compared with that of the source area, control area, as well as with the WHO and some international drinking water quality standards. The results show that some parameters, i.e., TDS, DO, pH, and hardness, were more than the permissible limits. Textile and glass industries were found to be the major sources of Hg and As pollution. Downstream dilution of these contaminants was also observed.",
Arsenic,2298740,"Laser ablation synthesis of new gold arsenides using nano-gold and arsenic as precursors. Laser desorption ionisation time-of-flight mass spectrometry and spectrophotometry Abstract: <strong>RATIONALE: </strong>Currently, a limited number of gold arsenides have been described, some of which have important industrial applications, Laser ablation synthesis (LAS) has been employed in an attempt to generate some novel gold arsenide compounds.<br /><br /><strong>METHODS: </strong>LAS of gold arsenides was performed using nano-gold (NG) and arsenic as precursors. The clusters formed during laser desorption ionisation (LDI) were analysed by mass spectrometry using a quadrupole ion trap and reflectron time-of-flight analyser to determine the stoichiometry. UV/VIS spectrophotometry was used to follow possible hydrothermal synthesis of gold arsenides.<br /><br /><strong>RESULTS: </strong>LAS of NG yielded singly charged gold clusters Aum (+(-)) (m?=?1-35). LAS of bulk arsenic and nano-arsenic produced Asn (+(-)) clusters with n?=?2-10 and n?=?2-20, respectively. Laser ablation of Au-As nano-composites or NG-As mixtures generated Aum (+(-)) (m?=?1-12), Asn (+(-)) (n?=?3-4), and several series of Aum Asn (+(-)) (m?=?1-60, n?=?1-18) clusters. Over 450 species of gold arsenide clusters and 212 mixed chlorinated Aum Asn Clx clusters were detected and their stoichiometry determined.<br /><br /><strong>CONCLUSIONS: </strong>Many new gold arsenides were synthesised via LAS for the first time with Au-As composites and NG-As mixtures of different Au:As ratios using mass spectrometry to determine cluster stoichiometry. The resolved stoichiometry of Aum Asn clusters determined in this study could accelerate the development of advanced Au-As nano-materials.",
Arsenic,1509350,"Changes in Sb speciation with waterlogging of shooting range soils and impacts on plant uptake Abstract: A pot experiment was conducted to investigate the solubility and redox species of antimony (Sb) in a relocated shooting range soil and its uptake by Lolium perenne L. and Holcus lanatus L. under different water regimes. After 1-week waterlogging, the total Sb concentration in soil solution decreased from ?110 ?g L(-1) to &lt;20 ?g L(-1), and slowly increased over the following 4 weeks, with the dissolution of Fe and Mn (hydr)oxides. In this process, half of the Sb in soil solution was reduced to Sb(III), which greatly affected the plant uptake of Sb. Waterlogging increased shoot Sb concentrations of L. perenne by ?10 fold but decreased uptake in H. lanatus by 80%. Results indicate that Sb might primarily be taken up as Sb(III) by L. perenne and as Sb(V) by H. lanatus. Temporary waterlogging of soil may increase the risk of trace elements entering the food chain.",
Arsenic,2278504,"Trace metal distribution in pristine permafrost-affected soils of the Lena River delta and its hinterland, northern Siberia, Russia Abstract: Soils are an important compartment of ecosystems and have the ability to buffer and immobilize substances of natural and anthropogenic origin to prevent their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since Arctic ecosystems are considered to be highly sensitive to climatic changes as well as to chemical contamination. This study characterises background levels of trace metals in permafrost-affected soils of the Lena River delta and its hinterland in northern Siberia (73.5–69.5° N), representing a remote region far from evident anthropogenic trace metal sources. Investigations on the element content of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co), and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest median concentrations of Fe and Mn were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) while the highest median values of Ni, Pb and Zn were found in soils of both the ice-complex and the Holocene estuarine terrace of the Lena River delta region, as well as in the southernmost study unit of the hinterland area. Detailed observations of trace metal distribution on the micro scale showed that organic matter content, soil texture and iron-oxide contents influenced by cryogenic processes, temperature, and hydrological regimes are the most important factors determining the metal abundance in permafrost-affected soils. The observed range of trace element background concentrations was similar to trace metal levels reported for other pristine northern areas.",
Arsenic,1031076,"Arsenic intake and excretion by Japanese adults: a 7-day duplicate diet study Abstract: The amount of arsenic in the urine, faeces and in duplicate diets of two couples who had eaten customary Japanese meals were monitored for 7 days by arsine-generator atomic absorption spectrophotometry. For the four volunteers, the mean daily intake of arsenic from their diets was 182 micrograms (range 27 to 376 micrograms). The dietary arsenic was composed of 5.7% inorganic arsenic, 3.6% methylarsonic acid, 27.4% dimethylarsinic acid and 47.9% trimethylarsenic compounds. The mean amounts of arsenic eliminated daily in urine and faeces were 148 micrograms (50-416 micrograms) and 46 micrograms (0-138 micrograms), respectively. The urinary arsenic was composed of 1.4% inorganic arsenic, 3.5% methylarsonic acid, 33.6% dimethylarsinic acid and 61.4% trimethylarsenic compounds. The daily intake of arsenic influenced the total amount of arsenic excreted in the urine (r = 0.7302, P less than 0.01) and the amount eliminated in the faeces (r = 0.5900, P less than 0.01) the next day. Specifically, there was also a significant correlation between the daily intakes of trimethylarsenic compounds and dimethylarsinic acid and the amounts of these compounds found in the urine the following day (r = 0.6833, P less than 0.01 and r = 0.6630, P less than 0.01, respectively). Considering the amounts of arsenic compounds present in seafood and in other components of the diet together with the urinary elimination patterns of arsenic compounds, it seemed probable that the trimethylarsenic compounds in the urine originated largely from fish and shellfish, which contain mainly arsenobetaine. Trimethylarsenic compounds in the urine should therefore be the preferred indicator of arsenic arising from the ingestion of seafood, especially fish and shellfish. In this study, the mean daily intake of inorganic arsenic from the diet (0.18 micrograms/kg) did not exceed the FAO/WHO JECFA Tolerable Daily Intake of 2 micrograms inorganic arsenic kg.",
Arsenic,2343450,"Heterogeneous arsenic enrichment in meta-sedimentary rocks in central Maine, United States Abstract: Arsenic is enriched up to 28 times the average crustal abundance of 4.8mgkg(-1) for meta-sedimentary rocks of two adjacent formations in central Maine, USA where groundwater in the bedrock aquifer frequently contains elevated As levels. The Waterville Formation contains higher arsenic concentrations (mean As 32.9mgkg(-1), median 12.1mgkg(-1), n=38) than the neighboring Vassalboro Group (mean As 19.1mgkg(-1), median 6.0mgkg(-1), n=38). The Waterville Formation is a pelitic meta-sedimentary unit with abundant pyrite either visible or observed by scanning electron microprobe. Concentrations of As and S are strongly correlated (r=0.88, p&lt;0.05) in the low grade phyllite rocks, and arsenic is detected up to 1944mgkg(-1) in pyrite measured by electron microprobe. In contrast, statistically significant (p&lt;0.05) correlations between concentrations of As and S are absent in the calcareous meta-sediments of the Vassalboro Group, consistent with the absence of arsenic-rich pyrite in the protolith. Metamorphism converts the arsenic-rich pyrite to arsenic-poor pyrrhotite (mean As 1mgkg(-1), n=15) during de-sulfidation reactions: the resulting metamorphic rocks contain arsenic but little or no sulfur indicating that the arsenic is now in new mineral hosts. Secondary weathering products such as iron oxides may host As, yet the geochemical methods employed (oxidative and reductive leaching) do not conclusively indicate that arsenic is associated only with these. Instead, silicate minerals such as biotite and garnet are present in metamorphic zones where arsenic is enriched (up to 130.8mgkg(-1) As) where S is 0%. Redistribution of already variable As in the protolith during metamorphism and contemporary water-rock interaction in the aquifers, all combine to contribute to a spatially heterogeneous groundwater arsenic distribution in bedrock aquifers.",
Arsenic,1519022,"Toxicogenomic approaches for understanding molecular mechanisms of heavy metal mutagenicity and carcinogenicity Abstract: Heavy metals that are harmful to humans include arsenic, cadmium, chromium, lead, mercury, and nickel. Some metals or their related compounds may even cause cancer. However, the mechanism underlying heavy metal-induced cancer remains unclear. Increasing data show a link between heavy metal exposure and aberrant changes in both genetic and epigenetic factors via non-targeted multiple toxicogenomic technologies of the transcriptome, proteome, metabolome, and epigenome. These modifications due to heavy metal exposure might provide a better understanding of environmental disorders. Such informative changes following heavy metal exposure might also be useful for screening of biomarker-monitored exposure to environmental pollutants and/or predicting the risk of disease. We summarize advances in high-throughput toxicogenomic-based technologies and studies related to exposure to individual heavy metal and/or mixtures and propose the underlying mechanism of action and toxicant signatures. Integrative multi-level expression analysis of the toxicity of heavy metals via system toxicology-based methodologies combined with statistical and computational tools might clarify the biological pathways involved in carcinogenic processes. Although standard in vitro and in vivo endpoint testing of mutagenicity and carcinogenicity are considered a complementary approach linked to disease, we also suggest that further evaluation of prominent biomarkers reflecting effects, responses, and disease susceptibility might be diagnostic. Furthermore, we discuss challenges in toxicogenomic applications for toxicological studies of metal mixtures and epidemiological research. Taken together, this review presents toxicogenomic data that will be useful for improvement of the knowledge of carcinogenesis and the development of better strategies for health risk assessment.",
Arsenic,1020180,"Arsenic induces peroxynitrite generation and cyclooxygenase-2 protein expression in aortic endothelial cells: Possible role in atherosclerosis Abstract: Epidemiological evidence suggests that exposure to the metalloid arsenic constitutes a risk factor for cardiovascular disease. The purpose of this study was to determine whether arsenic could stimulate generation of factors involved in oxidative stress and inflammation, conditions associated with atherosclerosis, or coronary artery disease. We found that production of peroxynitrite, a strong oxidant formed from the coupling of nitric oxide and superoxide anion, was significantly increased in bovine aortic endothelial (BAE) cells exposed to sodium arsenite at concentrations as low as 0.5 microM. Expression of the inflammatory mediator cyclooxygenase-2 (COX-2) was also upregulated in response to arsenite exposure as demonstrated by Western blot analysis. The increase in COX-2 protein was time dependent with highest levels at 30 min and 48 h. This result was supported by an increase in the generation of prostaglandin E(2) following exposure to arsenic. Nitrotyrosine residues in proteins are indicative of peroxynitrite generation, and extensive nitrotyrosine formation has been detected in atherosclerotic plaques. Therefore, COX-2 protein was immunoprecipitated from BAE cells and submitted to Western blot analysis using an antibody to nitrotyrosine. Nitration of COX-2 was detected in arsenic-treated cells, but not in untreated control cells. The findings in this report suggest an increase in reactive species, notably peroxynitrite, in BAE cells exposed to arsenic. Furthermore, induction of important inflammatory mediators such as COX-2 may exacerbate the inflammatory state typical of atherosclerosis.",
Arsenic,2343436,"Effect of Weak Magnetic Field on Arsenate and Arsenite Removal from Water by Zerovalent Iron: An XAFS Investigation Abstract: In this study, a weak magnetic field (WMF), superimposed with a permanent magnet, was utilized to improve ZVI corrosion and thereby enhance As(V)/As(III) removal by ZVI at pHini 3.0-9.0. The experiment with real arsenic-bearing groundwater revealed that WMF could greatly improve arsenic removal by ZVI even in the presence of various cations and anions. The WMF-induced improvement in As(V)/As(III) removal by ZVI should be primarily associated with accelerated ZVI corrosion, as evidenced by the pH variation, Fe(2+) release, and the formation of corrosion products as characterized with X-ray absorption fine structure spectroscopy. The arsenic species analysis in solution/solid phases at pHini 3.0 revealed that As(III) oxidation to As(V) in aqueous phase preceded its subsequent sequestration by the newly formed iron (hydr)oxides. However, both As(V) adsorption following As(III) oxidation to As(V) in solution and As(III) adsorption preceding its conversion to As(V) in solid phase were observed at pHini 5.0-9.0. The application of WMF accelerated the transformation of As(III) to As(V) in both aqueous and solid phases at pHini 5.0-9.0 and enhanced the oxidation of As(III) to As(V) in solution at pHini 3.0.",
Arsenic,1032405,"Cellular retention, toxicity and carcinogenic potential of seafood arsenic. I. Lack of cytotoxicity and transforming activity of arsenobetaine in the BALB/3T3 cell line Abstract: Cytotoxicity, morphological neoplastic transformation, intracellular retention and metabolic behaviour have been investigated in BALB/3T3 Cl A 31-1-1 cells for arsenobetaine, the main form of arsenic in certain seafoods, in comparison to inorganic sodium arsenite. In order to avoid false results, particular attention was paid to the purity, checking for the presence of any trace amounts of inorganic arsenic as well as methylated contaminants in the chemically synthesized arsenobetaine. Cytotoxicity and morphological transformation assays gave obvious positive results for sodium arsenite at a dose exposure of 10 microM. On the other hand, concentrations of arsenobetaine as high as 500 microM failed to induce either cytotoxic effects or neoplastic transformations. The absence of cytotoxicity and transforming potential of arsenobetaine in comparison to inorganic arsenite can be explained by the different degree of retention and the intracellular behaviour of the two arsenic species. Cellular retention of arsenobetaine was dose dependent for exposure concentrations ranging from 1 to 500 microM with a mechanism resembling a simple diffusion (1.4 and 760 pmol of As/10(6) cells were cell associated for the two concentrations at 24 h respectively). About 95% of the intracellular arsenobetaine was present in the cytosol fraction and the attempt to detect any intracellular degradation of the organoarsenic compound failed. Thus, the low retention efficiency of arsenobetaine, its inability to interact with intracellular components and the absence of biotransformation in the cell could explain the lack of cytotoxicity and transforming potential observed in the BALB/3T3 cells. These findings reinforce the view that in humans exposed to different chemical species of arsenic the contribution to the total health risk, including the carcinogenic potential, of arsenobetaine ingested with marine foodstuffs would be negligible.",
Arsenic,1030913,"An industrial hygiene evaluation of chimney sweeping Abstract: With the increased use of wood and coal for home heating, chimney sweeping is becoming a more common occupation. A preliminary study was designed to evaluate the air contaminants present in the process. Arsenic and sulfur dioxide were found along with coal tar pitch volatiles. A method of minimizing the exposure of these chemicals to chimney sweeps by spraying a water mist is discussed.",
Arsenic,1519200,"Does returning sites of historic peri-urban waste disposal to vegetable production pose a risk to human health? - A case study near Manchester, UK Abstract: Urban waste disposal occurred on fenland to the west of Manchester, England, between 1900 and 1964. The reclaimed fenland, Chat Moss, is now used for mixed arable farming. A total of 1.92 Mt of waste including privy midden, street sweepings, clinkers and slaughterhouse refuse was incorporated into the moss resulting in a modified topsoil with raised pH and reduced organic matter content compared with the subsoil. Elevated levels of potentially toxic elements (PTEs) are observed in the topsoil beyond the typical depth of atmospheric contamination; Cd and As concentrations exceed soil guideline values (SGVs) at 1.8 and 43 mg/kg, respectively. Sequential extraction indicates that waste-derived Pb, Zn and Ni remain predominantly in the residual fraction, whereas Cu was mainly organically bound. Arsenic was predominately found in oxide and organic matter fractions with Cd in carbonate, oxide, organic matter and residual fractions. Pot trials indicated limited uptake of PTEs by vegetables grown on the waste-amended soil, with the exception of Cd uptake by lettuce (0.22 mg/kg FW) and Pb uptake by radish (0.16 mg/kg FW), which exceeded current EU limits of 0.2 and 0.1 mg/kg FW, respectively. Hazard quotients (HQs) identified no risks to adults from consumption of vegetables grown in these soils with the exception of lettuce consumption with a HQ of 1.4. Risks to children were slightly greater with HQs >1 for Cd in lettuce, spinach, carrots and onion, As in lettuce, parsley and onion and for Zn in spinach.",
Arsenic,1017576,"Arsenite exposure downregulates EAAT1/GLAST transporter expression in glial cells Abstract: Chronic exposure to inorganic arsenic severely damages the central nervous system (CNS). Glutamate (GLU) is the major excitatory amino acid and is highly neurotoxic when levels in the synaptic cleft are not properly regulated by a family of Na?-dependent excitatory amino acid transporters. Within the cerebellum, the activity of the Bergmann glia Na?-dependent GLU/aspartate transporter (GLAST) excitatory amino acid transporter 1 (EAAT1/GLAST) accounts for more than 90% of GLU uptake. Because exposure to the metalloid arsenite results in CNS toxicity, we examined whether EAAT1/GLAST constitutes a molecular target. To this end, primary cultures of chick cerebellar Bergmann glial cells were exposed to sodium arsenite for 24 h, and EAAT1/GLAST activity was evaluated via ³H-D-aspartate uptake. A sharp decrease in GLU transport was observed, and kinetic studies revealed protein kinase A, protein kinase C, and p38 mitogen-activated protein kinase-dependent decreases in K(M) and V(max) concomitant with diminished chglast transcription. To gain insight into the molecular mechanisms involved in these phenomena, we investigated the generation of reactive oxidative species and the lipid peroxidative damage caused by arsenite exposure. None of these responses were found, although we did observe an increase in nuclear factor (erythroid-derived 2)-like 2 DNA-binding activity correlated with a rise in total glutathione levels. Our results clearly suggest that EAAT1/GLAST is a molecular target of arsenite and support the critical involvement of glial cells in brain function and dysfunction.",
Arsenic,1353231,"Cellulomonas carbonis sp nov., isolated from coal mine soil Abstract: ",
Arsenic,1579364,"Phosphate transporters expression in rice (Oryza sativa L.) associated with arbuscular mycorrhizal fungi (AMF) colonization under different levels of arsenate stress Abstract: It is known that arsenate and phosphate (P) share the same transporters in plants, and arbuscular mycorrhizal fungi (AMF) influence the expressions of Pi transporters (OsPT1–13) in rice. In order to study the effects of AMF on arsenate accumulation in rice, Glomus intraradices (AH01) was inoculated to rice and treated with different levels of arsenate (0, 2 and 8 ?M). Results revealed that OsPT11 was increased whereas OsPT2 decreased (P < 0.05) in mycorrhizal plants. The increased expression of OsPT11 was one of the most important factors that led to the significantly higher P concentration (P < 0.05) in plant tissues, which compensated the down-regulation of OsPT2. The symbiosis of G. intraradices with rice slightly decreased (P > 0.05) the arsenate concentration in plant tissues but markedly enhanced (P < 0.05) plant biomass. The higher P content in mycorrhizal plants led to the higher P/As molar ratio (P < 0.05) and lower As uptake ratio (P < 0.05) in mycorrhizal plants treated by 2 ?M arsenate. Mycorrhizal plants under such an arsenate treatment took up less As by per unit of root dry mass. The inoculation of G. intraradices was not able to transform the inorganic As to organic As. Further studies should be conducted focusing on the transport activities of each Pi transporter using yeast or oocyte expression system to identify which Pi transporters are responsible for the accumulation of arsenate.",
Arsenic,2343532,"Arsenic(V) Reduction in Relation to Iron(III) Transformation and Molecular Characterization of the Structural and Functional Microbial Community in Sediments of a Basin-Fill Aquifer in Northern Utah Abstract: Basin-fill aquifers of the Southwestern United States are associated with elevated concentrations of arsenic (As) in groundwater. Many private domestic wells in the Cache Valley Basin, UT, have As concentrations in excess of the U.S. EPA drinking water limit. Thirteen sediment cores were collected from the center of the valley at the depth of the shallow groundwater and were sectioned into layers based on redoxmorphic features. Three of the layers, two from redox transition zones and one from a depletion zone, were used to establish microcosms. Microcosms were treated with groundwater (GW) or groundwater plus glucose (GW + G) to investigate the extent of As reduction in relation to iron (Fe) transformation and characterize the microbial community structure and function by sequencing 16S rRNA and arsenate dissimilatory reductase (arrA) genes. Under the carbon-limited conditions of the GW treatment, As reduction was independent of Fe reduction, despite the abundance of sequences related to Geobacter and Shewanella, genera that include a variety of dissimilatory iron-reducing bacteria. The addition of glucose, an electron donor and carbon source, caused substantial shifts toward domination of the bacterial community by Clostridium-related organisms, and As reduction was correlated with Fe reduction for the sediments from the redox transition zone. The arrA gene sequencing from microcosms at day 54 of incubation showed the presence of 14 unique phylotypes, none of which were related to any previously described arrA gene sequence, suggesting a unique community of dissimilatory arsenate-respiring bacteria in the Cache Valley Basin.",
Arsenic,1025465,"Positive signaling interactions between arsenic and ethanol for angiogenic gene induction in human microvascular endothelial cells Abstract: Arsenic in the drinking water may promote vascular diseases in millions of people worldwide through unresolved mechanisms. In addition, little is known of the effects of coexposures to arsenic and other common vasculature toxicants, such as alcohol. To investigate signaling interactions between arsenic and alcohols, primary human microvascular endothelial (HMVEC) cells were exposed to noncytotoxic concentrations of arsenite (1-5 microM) in the presence or absence of 0.1% ethanol (EtOH). Coexposure, but not exposure to either agent alone, rapidly increased active Fyn tyrosine kinase, tyrosine phosphorylation of a 109-kDa protein and serine phosphorylation of protein kinase C (PKC)delta. The 109-kDa protein was identified as PYK2, a regulator of vascular integrin signaling and an upstream activator of PKCdelta. Membrane localization of phospholipase Cgamma1 was increased by coexposure within 15 min, but not by either agent alone. In contrast, both agents equally increased membrane localization of Rac1-GTPase. Coexposure, but not exposure to either agent alone, induced transcript levels for the angiogenic genes, vascular endothelial cell growth factor (Vegfa) and insulin-like growth factor-1 (Igf1). However, EtOH inhibited arsenic-induced, nuclear factor-kappaB-driven interleukin-8 and collagen-1 expression. Differential effects of selective PKC inhibitors on induced gene expression combined with a lack of interaction for induction of hemeoxygenase-1 further demonstrated that arsenic-responsive signaling pathways differ in sensitivity to EtOH interactions. Finally, coexposure enhanced endothelial tube formation in in vitro angiogenesis assays. These data indicate that complex interactions occur between arsenic and EtOH exposures that functionally affect endothelial signaling for gene induction and remodeling stimuli.",
Arsenic,659732,"Perturbations in immune responses induced by concurrent subchronic exposure to arsenic and endosulfan Abstract: The metalloid arsenic and the chlorinated insecticide endosulfan are common environmental contaminants. Humans, animals, and birds are exposed to these chemicals through water and food. Although health effects due to either arsenic or endosulfan exposure are documented, the toxicological impact of co-exposure to these environmental pollutants is unpredictable and unknown. The present study was undertaken to assess whether concurrent exposure to arsenic and endosulfan induces significant alterations in immunological functions. Day-old chicks were exposed to 3.7 ppm of arsenic via drinking water and to 30 ppm of endosulfan-mixed feed either individually or concurrently for up to 60 days. All the chicks were vaccinated with Ranikhet disease virus (F-strain; RD-F) on days 1 and 30. During the course of study and at term, parameters of cellular and humoral immunity were determined. None of the treatments altered the absolute body weight or body weight gain, except arsenic significantly reduced weight gain on day 60. Absolute, but not the relative, weights of spleen, thymus and bursa of Fabricius were significantly reduced in all the treatment groups. The metalloid and insecticide combination significantly depressed the ability of peripheral blood and splenic lymphocytes to proliferate in response to antigen RD-F and mitogen Con A. The delayed type hypersensitivity response to 2,4-dinitro-1-chlorobenzene or to PHA-P was also significantly decreased. Nitric oxide production by RD-F or lipopolysaccharide-stimulated peripheral blood and splenic mononuclear cells was significantly suppressed following concurrent exposure to arsenic and endosulfan. Furthermore, the combined exposure also decreased the antibody response to RD-F. The suppression of cellular and humoral immune responses was also evident following administration of individual compounds, and it was not exacerbated following concurrent exposure. To our knowledge, this is the first report describing the suppression of immune responses following exposure to arsenic alone or in combination with endosulfan at environmentally realistic concentrations in avian species. Therefore, immunotoxicological effects induced by concurrent exposure to arsenic and chlorinated pesticides should be considered when assessing the risk to human and animal health.",
Arsenic,734907,"Beclin-1 expression in normal bladder and in Cd2+ and As3+ exposed and transformed human urothelial cells (UROtsa) Abstract: The expression of beclin-1 in normal human bladder and in Cd(2+) and As(3+) exposed and transformed urothelial cells (UROtsa) was examined in this study. It was shown using a combination of real-time PCR, Western analysis and immunohistochemistry that beclin-1 was expressed in the urothelial cells of the normal bladder. It was also demonstrated that the parental UROtsa cell line expressed beclin-1 mRNA and protein at levels similar to that of the in situ urothelium. The level of beclin-1 expression underwent only modest alterations when the UROtsa cells were malignantly transformed by Cd(2+) or As(3+) or when the parental cells were exposed acutely to Cd(2+) or As(3+). While there were instances of significant alterations at individual time points and within cell line-to-cell line comparisons there was no evidence of a dose-response relationship or correlations to the phenotypic properties of the cell lines. Similar results were obtained for the expression of the Atg-5, Atg-7, Atg-12 and LC3B autophagy-related proteins. The findings provide initial evidence for beclin-1 expression in normal bladder and that large alterations in the expression of beclin-1 and associated proteins do not occur when human urothelial cells are malignantly transformed with, or exposed to, either Cd(2+) or As(3+.).",
Arsenic,1354056,"ALTERNATIVE 5' SPLICE-SITE SELECTION INDUCED BY HEAT-SHOCK Abstract: The mouse HSP47 gene consists of six exons separated by five introns. Three HSP47 cDNAs differing only in their 5' noncoding regions have been reported. One of these alternatively spliced mRNAs was detected only after heat shock, which caused an alternative 5' splice donor site selection. Other stress inducers, including an amino acid analog and sodium arsenite, had no effect on the alternative splicing. The alternatively spliced mRNA, which was 169 nucleotides longer in the 5' noncoding region compared to mRNA transcribed in non-heat shock conditions, was efficiently translated under heat shock conditions. This novel finding that alternative splicing is caused by artificial treatment like heat shock will provide a useful in vivo model for understanding the exon-intron recognition mechanism as well as heat shock-induced alterations in gene expression.",
Arsenic,1579251,"Spleen Stiffness in Patients With Cirrhosis in Predicting Esophageal Varices Abstract: OBJECTIVES:Screening for esophageal varices (EV) is recommended in patients with cirrhosis. Noninvasive tests had shown varying sensitivity (Se) and specificity (Sp) for predicting EV. Splenomegaly is a common finding in liver cirrhosis because of portal and splenic congestion. These changes can be quantified by transient elastography; hence, the aim of this study was to investigate the utility of spleen stiffness (SS) in evaluating EV in comparison with other noninvasive tests.METHODS:We measured SS and liver stiffness (LS) by using FibroScan in 200 consecutive cirrhotic patients who met the inclusion criteria. Patients were also assessed by hepatic venous pressure gradient (HVPG), upper gastrointestinal endoscopy, LS-spleen diameter to platelet ratio score (LSPS), and platelet count to spleen diameter ratio (PSR).RESULTS:Of 200 patients enrolled, 174 patients had valid LS and SS measurement, and 124 (71%) patients had EV (small, n=46 and large n=78). There was a significant difference in median LS (51.4 vs. 23.9?kPa, P=0.001), SS (54 vs. 32?kPa, P=0.001), LSPS (6.1 vs. 2.5, P=0.001), and PSR (812 vs. 1,165, P=0.001) between patients with EV and those without EV. LS ?27.3?kPa had an Se of 91%, Sp of 72%, positive predictive value (PPV) of 89%, negative predictive value (NPV) of 76%, and a diagnostic accuracy of 86% in predicting EV. LSPS ?3.09 had Se and Sp of 89% and 76%, respectively, and a PSR cutoff value of 909 or less had Se of 64%, Sp of 76%, and diagnostic accuracy of 68% in predicting EV. SS ?40.8?kPa had Se (94%), Sp (76%), PPV (91%), NPV (84%), and diagnostic accuracy of 86% for predicting EV. SS was significantly higher in patients who had large varices (56 vs. 49?kPa, P=0.001) and variceal bleed (58 vs. 50.2?kPa, P=0.001). Combining LS+SS (27.3+40.8?kPa) had Se of 90%, Sp 90%, PPV 96%, NPV 79%, and a diagnostic accuracy of 90%. HVPG (n=52) showed significant correlation with SS (r=0.433, P=0.001), LSPS (r=0.335, P=0.01), and PSR (r=-0.270, P=0.05), but not with LS (r=0.178, P=0.20).CONCLUSIONS:Measurement of SS can be used for noninvasive assessment of EV and can differentiate large vs. small varices and nonbleeder vs. bleeder.Am J Gastroenterol advance online publication, 30 April 2013; doi:10.1038/ajg.2013.119.",
Arsenic,1018290,"Arsenite exposure in human lymphoblastoid cell lines induces autophagy and coordinated induction of lysosomal genes Abstract: Chronic exposure to inorganic arsenic is associated with diverse, complex diseases, making the identification of the mechanism underlying arsenic-induced toxicity a challenge. An increasing body of literature from epidemiological and in vitro studies has demonstrated that arsenic is an immunotoxicant, but the mechanism driving arsenic-induced immunotoxicity is not well established. We have previously demonstrated that in human lymphoblastoid cell lines (LCLs), arsenic-induced cell death is strongly associated with the induction of autophagy. In this study we utilized genome-wide gene expression analysis and functional assays to characterize arsenic-induced effects in seven LCLs that were exposed to an environmentally relevant, minimally cytotoxic, concentration of arsenite (0.75 ?M) over an eight-day time course. Arsenic exposure resulted in inhibition of cellular growth and induction of autophagy (measured by expansion of acidic vesicles) over the eight-day exposure duration. Gene expression analysis revealed that arsenic exposure increased global lysosomal gene expression, which was associated with increased functional activity of the lysosome protease, cathepsin D. The arsenic-induced expansion of the lysosomal compartment in LCL represents a novel target that may offer insight into the immunotoxic effects of arsenic.",
Arsenic,2278258,"Arsenic hexoxide inhibits NF-kappa B activity through, at least in part, suppression of I kappa B alpha phosphorylation in MCF-7 human breast cancer cells Abstract: Arsenic hexoxide (As4O6) has been used in Korean folk remedy for the treatment of cancer since the late 1980’s. Evidence suggests that the anti-cancer effects of As4O6 are different from those of As2O3. Nuclear factor-{kappa}B (NF-{kappa}B) is a well-known transcription factor involved in cell proliferation, invasion and metastasis. Here, we investigated the effects of As4O6 on NF-{kappa}B activity, NF-{kappa}B-regulated gene expressions, and NF-{kappa}B-mediated cellular responses. As4O6 suppressed NF-{kappa}B activation induced by TNF-?, and the some of the downstream NF-{kappa}B-regulated proteins involved in caner proliferation, metastasis and anti-apoptosis. As4O6 also suppressed I{kappa}B phosphorylation in a time-dependent manner, suggesting the suppression of NF-{kappa}B results from at least in part by inhibiting I{kappa}B degradation. We also confirmed the anti-NF-{kappa}B activity of As4O6 with synergism with TNF-? at the molecular levels. This study demonstrates that As4O6 inhibits NF-{kappa}B activation and NF-{kappa}B regulated proteins at least in part through the inhibition of I{kappa}B phosphorylation. [This study was supported by a grant from the National R&D Program for Cancer Control, Ministry for Health, Welfare & Family Affairs, Republic of Korea. (0820050), and National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (20120002631).]",
Arsenic,1597332,"Arsenic K-edge X-ray absorption near-edge spectroscopy to determine oxidation states of arsenic of a coastal aquifer-aquitard system Abstract: Determination of oxidation states of solid-phase arsenic in bulk sediments is a valuable step in the evaluation of its bioavailability and environmental fate in deposits, but is difficult when the sediments have low arsenic contents and heterogeneous distribution of arsenic species. As K-edge X-ray absorption near-edge spectroscopy (XANES) was used to determine quantitatively the oxidation states of arsenic in sediments collected from different depths of boreholes in the Pearl River Delta, China, where the highest aquatic arsenic concentration is 161.4 ?g/L, but the highest solid arsenic content only 39.6 mg/kg. The results demonstrated that XANES is efficient in determining arsenic oxidation states of the sediments with low arsenic contents and multiple arsenic species. The study on the high-resolution vertical variations of arsenic oxidation states also indicated that these states are influenced strongly by groundwater activities. With the help of geochemical data, solid arsenic speciation, toxicity and availability were further discussed.",
Arsenic,2149143,"Responses of wild small mammals to arsenic pollution at a partially remediated mining site in Southern France Abstract: Partial remediation actions at a former gold mine in Southern France led to a mosaic of contaminated and rehabilitated zones. In this study, the distribution of arsenic and its potential adverse effects on small mammals were investigated. The effectiveness of remediation for reducing the transfer of this element into wildlife was also discussed. Arsenic levels were measured in the soil and in the stomach contents, livers, kidneys, and lungs of four small mammal species (the wood mouse (Apodemus sylvaticus), the Algerian mouse (Mus spretus), the common vole (Microtus arvalis), and the greater white-toothed shrew (Crocidura russula)). The animals were caught at the former extraction site, in zones with three different levels of remediation treatments, and at a control site. Arsenic concentrations in the soil were highly spatially heterogeneous (ranging from 29 to 18,900?gg(-1)). Despite the decrease in arsenic concentrations in the remediated soils, both wood mice and Algerian mice experienced higher oral exposure to arsenic in remediated zones than in the control area. The accumulated arsenic in their organs showed higher intra-zonal variability than the arsenic distribution in the soil, suggesting that, in addition to remediation processes, other variables can help explain arsenic transfer to wildlife, such as the habitat and diet preferences of the animals or their mobility. A weak but significant correlation between arsenic concentration and body condition was observed, and weak relationships between the liver/kidney/lung mass and arsenic levels were also detected, suggesting possible histological alterations.",
Arsenic,711054,"Urine arsenic and hypertension in US adults: The 2003-2008 National Health and Nutrition Examination Survey Abstract: High chronic exposure to inorganic arsenic may contribute to the development of hypertension. Limited information is available, however, on the association of low to moderate exposure to inorganic arsenic with blood pressure levels and hypertension. We investigated the association of exposure to inorganic arsenic (as measured in urine) with systolic and diastolic blood pressure levels and the prevalence of hypertension in US adults.<br /><br /> We studied 4167 adults 20 years of age or older who participated in the National Health and Nutrition Examination Survey (NHANES) from 2003 through 2008 and for whom total arsenic, dimethylarsinate (DMA), and arsenobetaine had been assessed in urine.<br /><br /> The median (interquartile range) urine concentrations were 8.3 ?g/L (4.2-17.1) for total arsenic, 3.6 ?g/L (2.0-6.0) for DMA, and 1.4 ?g/L (0.3-6.3) for arsenobetaine. The weighted prevalence of hypertension in the study population was 36%. After multivariable adjustment, a 2-fold increase in total arsenic was associated with a hypertension odds ratio of 0.98 (95% confidence interval = 0.86-1.11). A doubling of total arsenic minus arsenobetaine was associated with a hypertension OR of 1.03 (0.94-1.14) and a doubling of DMA concentrations was associated with a hypertension OR of 1.11 (0.99-1.24). Total arsenic, total arsenic minus arsenobetaine, or DMA levels were not associated with systolic or diastolic blood pressure.<br /><br /> At the low to moderate levels, typical of the US population, total arsenic, total arsenic minus arsenobetaine, and DMA concentrations in urine were not associated with the prevalence of hypertension or with systolic or diastolic blood pressure levels. A weak association of DMA with hypertension could not be ruled out.",
Arsenic,49085,"A cross-sectional study of pulmonary function among workers exposed to multimetals in the glass bangle industry Abstract: Spirometric lung functions were evaluated in 220 asymptomatic glass bangle workers exposed to the salts of various heavy metals, such as arsenic, lead, zinc, copper, manganese, cobalt, cadmium, and selenium, which are used as coloring agents in the manufacture of glass bangles. The mean values of various spirometric variables (viz. FVC, FEV1, IMBC, and PEFR) were within normal range (more than 80% of the predicted values) in both smoking and nonsmoking glass bangle workers and did not reveal any significant differences in comparison with those observed in the unexposed controls. However, variables such as FEV1/FVC% ratio, FEF25-75 and FEF75-85 were reduced significantly (p less than 0.001) in the exposed group. The reduction was more marked in the smoking glass bangle workers indicating additive effect of cigarette smoking on the small airways. The exposed group showed a significantly higher prevalence (16.3%) of respiratory impairment in comparison to that observed in the controls (7.9%) as a result of exposure to various metals in the work environment (p less than 0.01). The respiratory impairment observed in the exposed group indicated primarily restrictive pattern of pulmonary abnormality (10.4%), while the controls revealed only 1.1% prevalence of this disease (p less than 0.001). The effect of the duration of exposure on the prevalence of respiratory impairment in the glass bangle industry revealed significantly higher prevalence (p less than 0.05) in those who worked for more than 10 years (23.0%) than in those who worked for less than 10 years (10.8%) thereby indicating that the duration of exposure is directly related to the prevalence of respiratory impairment.",
Arsenic,2278559,Dual-specificity Phosphatase 8 Promotes the Degradation of the Polyglutamine Protein Ataxin-1 Abstract: ,
Arsenic,1019773,"Oxidative stress, mitochondrial respiration, and glycemic control: clues from chronic supplementation with Cr3+ or As3+ to male Wistar rats Abstract: Multiple experiments in male Wistar rats were designed to clarify the role of mitochondrial dysfunction in the mechanisms of oxidative stress-related diseases and toxicity-induced pathologies. In this particular report, 21 male Wistar rats were supplemented ad libitum with either As3+ or Cr3+ salts in drinking water to assess insulin secretion patterns in vivo and in vitro, mitochondrial dysfunction, oxidative stress, liver damage, basal insulin, and glucose tolerance curves, among other parameters. Results were compared with a control group without any metal supplementation. The CrCl3 supplements were more invasive of metabolism and had a stronger effect on mitochondrial dysfunction than As3+, despite that both seem to use similar mechanisms of toxicity; viz.: binding to thiol or -SS- group in enzymes and proteins, and releasing oxidant species during their redox-cycling and metabolic activation processes, e.g., by cytochrome P450 in liver. Results support our aim to prove the influence of oxidative stress-induced mitochondrial dysfunction on glycemic control.",
Arsenic,2347777,"Effect of temperature on the rate of oxidation of pyrrhotite-rich sulfide ore flotation concentrate and the structure of the acidophilic chemolithotrophic microbial community Abstract: Oxidation of flotation concentrate of a pyrrhotite-rich sulfide ore by acidophilic chemolithoautotrophic microbial communities at 35, 40, and 45 degrees C was investigated. According to the physicochemical parameters of the liquid phase of the pulp, as well as the results of analysis of the solid residue after biooxidation and cyanidation, the community developed at 40 degrees C exhibited the highest rate of oxidation. The degree of gold recovery at 35, 40, and 45 degrees C was 89.34, 94.59, and 83.25%, respectively. At 40 degrees C, the highest number of microbial cells (6.01 x 10(9) cells/mL) was observed. While temperature had very little effect on the species composition of microbial communities (except for the absence of Leptospirillum ferriphilum at 35 degrees C), the shares of individual species in the communities varied with temperature. Relatively high numbers of Sulfobacillus thermosulfidooxidans, the organism oxidizing iron and elemental sulfur at higher rates than other acidophilic chemolithotrophic species, were observed at 40 degrees C.",
Arsenic,1032454,"Sodium arsenite induces ATP depletion and mitochondrial damage in HeLa cells Abstract: Our present results show that treatment with sodium arsenite apparently decreases cellular ATP levels in a dose- and time-dependent manner in HeLa S-3 cells. The reduction in ATP induced by sodium arsenite was possibly through mitochondrial damage, since treatment with sodium arsenite resulted in reduction of rhodamine 123 accumulation and disruption of the structure of the cristae in mitochondria. However, all of these changes could be reversed by removing sodium arsenite from the culture medium. The levels of ATP depletion were correlated with the killing effects of sodium arsenite in HeLa S-3 cells.",
Arsenic,1292201,"Arsenic contamination: a potential hazard to the affected areas of West Bengal, India Abstract: Arsenic contamination in groundwater is becoming more and more a worldwide problem. Nearing 50 million of people are at health risk from arsenic contamination at Ganga-Meghna-Bramhaputra basin. The experimental results of the five blocks under Malda district of West Bengal, India, showed that the arsenic concentration in groundwater (0.41-1.01 mg/l) was higher than the permissible limit for drinking water (0.01 mg/l) (WHO) and FAO (Food and Agriculture Organization) permissible limit for irrigation water (0.10 mg/l). The soil arsenic level (13.12 mg/kg) crossed the global average (10.0 mg/kg), but within the maximum acceptable limit for agricultural soil (20.0 mg/kg) recommended by the European Union. The total arsenic concentration on food crops varied from 0.000 to 1.464 mg/kg of dry weight. The highest mean arsenic concentration was found in potato (0.456 mg/kg), followed by rice grain (0.429 mg/kg). The total mean arsenic content (milligrams per kg dry weight) in cereals ranged from 0.121 to 0.429 mg/kg, in pulses and oilseeds ranged from 0.076 to 0.168 mg/kg, in tuber crops ranged from 0.243 to 0.456 mg/kg, in spices ranged from 0.031 to 0.175 mg/kg, in fruits ranged from 0.021 to 0.145 mg/kg and in vegetables ranged from 0.032 to 0.411 mg/kg, respectively. Hence, arsenic accumulation in cereals, pulses, oilseed, vegetables, spices, cole crop and fruits crop might not be safe in future without any sustainable mitigation strategies to avert the potential arsenic toxicity on the human health in the contaminated areas.",
Arsenic,1380651,"Inhibition of ICE-related proteases (caspases) and nuclear apoptosis by phenylarsine oxide Abstract: Biochemical analyses of nuclear apoptosis in vitro have revealed the existence of multiple active interleukin-1beta-converting enzyme-related proteases (caspases) with distinct substrate recognition properties in extracts of preapoptotic chicken DU249 cells (S/M extracts). Previously we demonstrated that the activity of a caspase that cleaves lamins is required for the disintegration of nuclei in the late stages of apoptosis, despite the presence of a second active caspase that cleaves poly(ADP-ribose) polymerase (PARP). One simple explanation for this observation was that the lamin-cleaving caspase is sufficient to drive the nuclear events of apoptotic execution. Here, we report that phenylarsine oxide (PAO) inhibits the protease activities of recombinant human caspases as well as endogenous chicken caspases that are active in S/M extracts. PAO at 100 microM blocks the morphological changes of nuclear apoptosis in vitro and internucleosomal DNA fragmentation in S/M extracts without interfering with PARP or lamin A cleavage. Thus, lamin cleavage is not sufficient to drive the changes in nuclear morphology characteristic of apoptosis. Affinity labeling with YV(bio)KD-aomk shows that the degree of sensitivity to PAO differs among active caspases in S/M extracts. These results suggest that a PAO-sensitive caspase that is distinct from the PARP- or lamin-cleaving enzymes is required for the initiation of apoptotic morphological changes and for the activation of endonuclease(s). Taken together, our results suggest that two or more caspases are required for proteolytic events that are essential for the initiation and completion of nuclear apoptotic changes. The observation that PAO is an inhibitor of caspases and nuclear apoptotic events should be useful for the biochemical dissection of apoptosis in vitro and in vivo.",
Arsenic,544515,"The association between low levels of lead in blood and occupational noise-induced hearing loss in steel workers Abstract: Abstract: As the use of leaded gasoline has ceased in the last decade, background lead exposure has generally been reduced. The aim of this study was to examine the effect of low-level lead exposure on human hearing loss. This study was conducted in a steel plant and 412 workers were recruited from all over the plant. Personal information such as demographics and work history was obtained through a questionnaire. All subjects took part in an audiometric examination of hearing thresholds, for both ears, with air-conducted pure tones at frequencies of 500, 1000, 2000, 3000, 4000, 6000 and 8000Hz. Subjects'' blood samples were collected and analyzed for levels of manganese, copper, zinc, arsenic, cadmium and lead with inductive couple plasma-mass spectrometry. Meanwhile, noise levels in different working zones were determined using a sound level meter with A-weighting network. Only subjects with hearing loss difference of no more than 15dB between both ears and had no congenital abnormalities were included in further data analysis. Lead was the only metal in blood found significantly correlated with hearing loss for most tested sound frequencies (p <0.05 to p <0.0001). After adjustment for age and noise level, the logistic regression model analysis indicated that elevated blood lead over 7ÃŽÂ¼g/dL was significantly associated with hearing loss at the sound frequencies of 3000 through 8000Hz with odds ratios raging from 3.06 to 6.26 (p <0.05~ p <0.005). We concluded that elevated blood lead at level below 10ÃŽÂ¼g/dL might enhance the noise-induced hearing loss. Future research needs to further explore the detailed mechanism. [Copyright &y& Elsevier]; Copyright of Science of the Total Environment is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)",
Arsenic,1030773,"c-Jun/AP-1 pathway-mediated cyclin D1 expression participates in low dose arsenite-induced transformation in mouse epidermal JB6 Cl41 cells Abstract: Arsenic is a well-documented human carcinogen associated with skin carcinogenesis. Our previous work reveals that arsenite exposure is able to induce cell transformation in mouse epidermal cell JB6 Cl41 through the activation of ERK, rather than JNK pathway. Our current studies further evaluate downstream pathway in low dose arsenite-induced cell transformation in JB6 Cl41 cells. Our results showed that treatment of cells with low dose arsenite induced activation of c-Jun/AP-1 pathway, and ectopic expression of dominant negative mutant of c-Jun (TAM67) blocked arsenite-induced transformation. Furthermore, our data indicated that cyclin D1 was an important downstream molecule involved in c-Jun/AP-1-mediated cell transformation upon low dose arsenite exposure, because inhibition of cyclin D1 expression by its specific siRNA in the JB6 Cl41 cells resulted in impairment of anchorage-independent growth of cells induced by low dose arsenite. Collectively, our results demonstrate that c-Jun/AP-1-mediated cyclin D1 expression is at least one of the key events implicated in cell transformation upon low dose arsenite exposure.",
Arsenic,1797769,"Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers Abstract: This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 ?g/L) and 54% of samples had As above the WHO drinking water guideline value of 10 ?g/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (?80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3¯, U, B, V, and Mo (R(2) &gt; 0.5; p &lt; 0.001). Chemical modeling of the groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated in the groundwater, suggesting that the As reactivity is controlled by adsorption/desorption processes with these minerals. The data show that As and other oxyanion-forming elements such as U, B, Mo, and V had typically higher concentrations at pH &gt; ?8, reflecting the pH-dependence of their mobilization. Based on the geochemical and stable isotope variations we have established a conceptual model for the occurrence of naturally occurring contaminants in MER groundwater: 1) regional groundwater recharge from the Highland, along the Rift margins, followed by lateral flow and water-rock interactions with the aquifer rocks resulted in a gradual increase of the salinity and naturally occurring contaminants towards the center of the valley; and (2) local ?(18)O-rich lake water recharge into adjacent shallow aquifers, followed by additional mobilization of As and other oxyanion-forming elements from the aquifer rocks. We posit that the combined physical-chemical conditions of the aquifers such as oxidizing state, Na-HCO3 composition, and pH&gt;?8 lead to enhanced mobilization of oxyanion-forming elements from Fe-oxides and consequently contamination of local groundwater. These geochemical conditions characterize groundwater resources along the Eastern African Rift and thus constitute a potential threat to the quality of groundwater in larger areas of Eastern Africa.",
Arsenic,1339116,"Rapid Equilibrium Kinetic Analysis of Arsenite Methylation Catalyzed by Recombinant Human Arsenic (+3 Oxidation State) Methyltransferase (hAS3MT) Abstract: In the human body, arsenic is metabolized by methylation. Understanding this process is important and provides insight into the relationship between arsenic and its related diseases. We used the rapid equilibrium kinetic model to study the reaction sequence of arsenite methylation. The results suggest that the mechanism for arsenite methylation is a completely ordered mechanism that is also of general interest in reaction systems with different reductants, such as tris(2-carboxyethyl)phosphine, cysteine, and glutathione. In the reaction, cysteine residues of recombinant human arsenic (+3 oxidation state) methyltransferase (hAS3MT) coordinate with arsenicals and involve the methyl transfer step. S-Adenosyl-l-methionine (AdoMet) is the first-order reactant, which modulates the conformation of hAS3MT to a best matched state by hydrophobic interaction. As the second-order reactant, reductant reduces the disulfide bond, most likely between Cys-250 and another cysteine residue of hAS3MT, and exposes the active site cysteine residues for binding trivalent inorganic arsenic (iAs(3+)) to give monomethylarsonic dicysteine (MADC(3+)). In addition, the reaction can be extended to further methylate MADC(3+) to dimethylarsinic cysteine (DAMC(3+)). In the methylation reaction, the ?-pleated sheet content of hAS3MT is increased, and the hydrophobicity of the microenvironment around the active sites is decreased. Similarly, we confirm that both the high ?-pleated sheet content of hAS3MT and the high dissociation ability of the enzyme-AdoMet-reductant improve the yield of dimethylated arsenicals.",
Arsenic,1030927,"Survival and mortality pattern among Swedish smelter workers Abstract: The study analyses work history and mortality data for 3919 male workers first employed during 1928-66 at Rönnskärsverken, a copper smelter in north-east Sweden. 99% of the workers were traced from employment records and central population registers. By means of standarized mortality ratios and life-table analysis comparisons were made with both the general and local populations. For all causes excess mortality is 18% relative to the general population. This can be ascribed to tumours and circulatory diseases, for which excess figures are 39 and 32% respectively. For tumours, the excess mortality is mainly due to lung cancer for which the risk is trebled relative to the general population and 5-fold relative to local populations. For circulatory diseases, the excess figure is mainly accounted for by cerebrovascular disease with an elevated risk of 60-70%. The probable remaining life-time from 50 years is 2 years shorter than for Swedish men in the 60's. Internal comparisons were made to analyse the importance of latency, exposure, calendar time and place of work. A dose-response analysis clearly indicates that the roasters and arsenic departments are risk places for the development of cancer, especially lung cancer. A 50-year old worker who has been exposed to the roasters for more than 5 years, has a probable remaining life-time which is almost 3 years shorter than the average Rönnskär employee and almost 5 years shorter than the average Swedish male. Case-control studies aimed at exploring exposure associated with stomach cancer and cerebrovascular mortality are under way.",
Arsenic,1022036,"Testing tubewell platform color as a rapid screening tool for arsenic and manganese in drinking water wells Abstract: A low-cost rapid screening tool for arsenic (As) and manganese (Mn) in groundwater is urgently needed to formulate mitigation policies for sustainable drinking water supply. This study attempts to make statistical comparison between tubewell (TW) platform color and the level of As and Mn concentration in groundwater extracted from the respective TW (n = 423), to validate platform color as a screening tool for As and Mn in groundwater. The result shows that a black colored platform with 73% certainty indicates that well water is safe from As, while with 84% certainty a red colored platform indicates that well water is enriched with As, compared to WHO drinking water guideline of 10 ?g/L. With this guideline the efficiency, sensitivity, and specificity of the tool are 79%, 77%, and 81%, respectively. However, the certainty values become 93% and 38%, respectively, for black and red colored platforms at 50 ?g/L, the drinking water standards for India and Bangladesh. The respective efficiency, sensitivity, and specificity are 65%, 85%, and 59%. Similarly for Mn, black and red colored platform with 78% and 64% certainty, respectively, indicates that well water is either enriched or free from Mn at the Indian national drinking water standard of 300 ?g/L. With this guideline the efficiency, sensitivity, and specificity of the tool are 71%, 67%, and 76%, respectively. Thus, this study demonstrates that TW platform color can be potentially used as an initial screening tool for identifying TWs with elevated dissolved As and Mn, to make further rigorous groundwater testing more intensive and implement mitigation options for safe drinking water supplies.",
Arsenic,628418,"A randomized, double-blind placebo-controlled trial evaluating the effects of vitamin E and selenium on arsenic-induced skin lesions in Bangladesh Abstract: OBJECTIVE: We sought to determine whether supplementation of vitamin E (alpha-tocopherol), selenium (L-selenomethionine), or their combination improves arsenical skin lesions. METHODS: A 2 x 2 randomized, placebo-controlled, double-blind trial among 121 men and women chronically exposed to arsenic in drinking water was conducted in rural Bangladesh. Participants were randomized to one of four treatment arms: vitamin E, selenium, vitamin E and selenium (combination), or placebo and were treated for 6 months. RESULTS: At baseline, the average skin lesion scores were 2.23, 2.26, and 2.63 and at follow-up, the average skin lesion scores went down to 2.00, 2.06, and 2.47 in those receiving vitamin E, selenium, and the combination, respectively. CONCLUSIONS: Supplementation with vitamin E and selenium, either alone or in combination, slightly improved skin lesion status, although the improvement was not statistically significant.",
Arsenic,2337216,"In situ stabilization of As and Sb with naturally occurring Mn, Al and Fe oxides in a calcareous soil: Bioaccessibility, bioavailability and speciation studies Abstract: This study investigated the effectiveness of 6 different types of naturally occurring manganese, aluminum and iron oxides for stabilization of As and Sb in a calcareous soil spiked with 50mgkg(-1) of As or Sb and two dosages of treatments (2% and 5%). The resulting contaminated soils were subjected to a series of chemical extraction studies including sequential extraction, single step extraction with DTPA and Simplified Bioaccessibility Extraction Test (SBET) for estimation of bioaccessible fraction of As and Sb in soil and a greenhouse experiment using barley as the test crop. The results showed that Fe-associated and carbonate-bound fraction of As and Sb were predominant fractions. However, the amounts of labile fractions were higher in As contaminated soils, whereas the percentage of Sb associated with crystalline Fe-oxide and residual fractions were higher. The results revealed that application of natural metal oxides reduced DTPA and SBET extractable amounts and plant uptake of As and Sb. After application of amendments, the exchangeable fraction of As decreased dramatically by up to 82% while Sb exchangeable fraction decreased by up to 60% depending upon the additive. The results of chemical extractions and plant uptake confirmed that Sb had lower bioavailability, compared with As.",
Arsenic,2347663,"Structure of Escherichia coli Grx2 in complex with glutathione: a dual-function hybrid of glutaredoxin and glutathione S-transferase Abstract: The structure of glutaredoxin 2 (Grx2) from Escherichia coli co-crystallized with glutathione (GSH) was solved at 1.60?Å resolution. The structure of a mutant with the active-site residues Cys9 and Cys12 changed to serine crystallized in the absence of glutathione was solved to 2.4?Å resolution. Grx2 has an N-terminal domain characteristic of glutaredoxins, and the overall structure is congruent with the structure of glutathione S-transferases (GSTs). Purified Grx2 exhibited GST activity. Grx2, which is the physiological electron donor for arsenate reduction by E. coli ArsC, was docked with ArsC. The docked structure could be fitted with GSH bridging the active sites of the two proteins. It is proposed that Grx2 is a novel Grx/GST hybrid that functions in two steps of the ArsC catalytic cycle: as a GST it catalyzes glutathionylation of the ArsC-As(V) intermediate and as a glutaredoxin it catalyzes deglutathionylation of the ArsC-As(III)-SG intermediate.",
Arsenic,628317,"Tissue distribution and retention of 74As-dimethylarsinic acid in mice and rats Abstract: The metabolism of dimethylarsinic acid (DMA), a common pesticide and the primary metabolite of inorganic arsenic in mammals, has been studied in mice and rats. About 80% of an oral dose (0.4 mg As/kg body weight) was absorbed from the gastrointestinal tract. In the mice, more than 99% of the dose was eliminated within 3 days, as compared to about 50% in the rats, mainly due to accumulation in the blood. The tissue distribution in the mice was characterized by highest initial (0.5–6 hr) concentrations in kidneys, lungs, intestinal mucosa, stomach, and testes. Tissues with longest retention time were lungs, thyroid, intestinal walls and lens. No demethylation of the74As-DMA to inorganic arsenic was observed, but some of the74As-DMA in the tissues was apparently in a complexed form. This work was performed within the framework of the contract of collaboration No. 1644-81-10 TS ISP S between the Commission of the European Communities and the National Institute of Environmental Medicine, Stockholm",
Arsenic,1030723,"Does arsenic exposure increase the risk for prostate cancer? Abstract: Arsenic has been well documented as the major risk factor for blackfoot disease (BFD), a unique peripheral vascular disease that was endemic to the southwestern coast of Taiwan, where residents consumed artesian well water containing high levels of arsenic for more than 50 yr. Chronic arsenic exposure was also reported to be associated with mortality attributed to prostate cancer in a dose-response relationship. A tap-water supply system was implemented in the early 1960s in the BFD-endemic areas in Taiwan. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study was to determine whether prostate cancer mortality decreased after the improvement of drinking-water supply system through elimination of arsenic ingestion from artesian well water. Standardized mortality ratios (SMRs) for prostate cancer were calculated for the BFD-endemic area for the years 1971-2006. Results showed that mortality attributed to prostate cancer declined gradually after the improvement of drinking-water supply system. Based on the reversibility criterion, the association between arsenic exposure and development of prostate cancer is likely to be causal.",
Arsenic,1340105,"Acute arsenic toxicity alters cytochrome P450 and soluble epoxide hydrolase and their associated arachidonic acid metabolism in C57Bl/6 mouse heart Abstract: Acute arsenic (As(III)) exposure has been reported to cause cardiac toxicity, however this toxicity was never linked to the disturbance in cytochrome P450 (P450)-mediated arachidonic acid metabolism. Therefore, we investigated the effect of acute As(III) toxicity on the expression of P450 and soluble epoxide hydrolase (sEH) and their associated arachidonic acid metabolism in mice hearts. As(III) toxicity was induced by a single intraperitoneal injection of 12.5 mg/kg of As(III). Our results showed that As(III) treatment caused a significant induction of the cardiac hypertrophic markers in addition to Cyp1b1, Cyp2b, Cyp2c, Cyp4f, and sEH gene expression in mice hearts. Furthermore, As(III) increased sEH protein expression and activity in hearts with a consequent decrease in 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs) formation. Whereas the formation of 8,9-, 11,12-, 14,15-dihydroxyeicosatrienoic acids (DHETs) was significantly increased. As(III) also increased sEH mRNA and protein expression levels in addition to the hypertrophic markers which was reversed by knockdown of sEH in H9c2 cells. In conclusion, acute As(III) toxicity alters the expression of several P450s and sEH enzymes with a consequent decrease in the cardioprotective EETs which may represent a novel mechanism by which As(III) causes progressive cardiotoxicity. Furthermore, inhibiting sEH might represent a novel therapeutic approach to prevent As(III)-induced hypertrophy.",
Arsenic,2337110,"Removal of arsenate with hydrous ferric oxide coprecipitation: Effect of humic acid Abstract: Insights from the adverse effect of humic acid (HA) on arsenate removal with hydrous ferric oxide (HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering (SERS), extended X-ray absorption fine structure (EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared (ATR-FTIR) measurement, and charge distribution multisite complexation (CD-MUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26-3.31 angstrom. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms inner-sphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well.",
Arsenic,2149300,Phosphate deficiency signaling pathway is a target of arsenate and phosphate transporter OsPT1 is involved in As accumulation in shoots of rice Abstract: ,
Arsenic,1020254,"Solar UV radiation enhances the toxicity of arsenic in Ceriodaphnia dubia Abstract: Extensive research exists regarding the toxicity of metals (including arsenic) to aquatic invertebrates. However, there has been little consideration of potential synergies between metals and ultraviolet (UV) radiation--despite considerable debate on this topic in human health research. Ultraviolet radiation is nearly ubiquitous in the natural environment, but it is generally overlooked as a confounding variable in toxicological assessments. We evaluate synergies between arsenic and solar UV radiation using the crustacean, Ceriodaphnia dubia. Both laboratory (with simulated solar radiation) and outdoor (with natural solar radiation) factorial experiments were performed with two intensities of UV (low and high) and four arsenic concentrations (0, 1, 1.25 and 1.5 mg/l). The laboratory experiment was multigenerational, examining survival and fecundity effects. The combination of high UV + 1.5 mg/l As adversely impacted survival; whereas, High UV + 0 mg/l As and Low UV + 1.5 mg/l As treatments did not. These results suggest synergism. This pattern was consistent for all three generations. Fecundity effects were not consistent across generations, and arsenic was demonstrated to have a greater impact than UV. Outdoor experiments were limited to assessing survival. Exposures in September 1999 resulted in a pattern similar to that in the laboratory exposure. High UV + 1.5 mg/l As treatment elicited diminished survival as compared to high UV + 0 mg/l As and low UV + 1.5 mg/l As. These results indicate that a synergistic effect between arsenic and UV exposure is possible under ambient conditions and within a relatively narrow dose range. The mechanism of this effect is unknown but could include synergistic genotoxic or oxidative stress. These findings point to the importance of using realistic UV exposures when determining criteria for protection of aquatic life.",
Arsenic,1519171,"Porphyrin and heme metabolism and the porphyrias Abstract: Porphyrins and metalloporphyrins are the key pigments of life on earth as we know it, because they include chlorophyll (a magnesium-containing metalloporphyrin) and heme (iron protoporphyrin). In eukaryotes, porphyrins and heme are synthesized by a multistep pathway that involves eight enzymes. The first and rate-controlling step is the formation of delta-aminolevulinic acid (ALA) from glycine plus succinyl CoA, catalyzed by ALA synthase. Intermediate steps occur in the cytoplasm, with formation of the monopyrrole porphobilinogen and the tetrapyrroles hydroxymethylbilane and a series of porphyrinogens, which are serially decarboxylated. Heme is utilized chiefly for the formation of hemoglobin in erythrocytes, myoglobin in muscle cells, cytochromes P-450 and mitochondrial cytochromes, and other hemoproteins in hepatocytes. The rate-controlling step of heme breakdown is catalyzed by heme oxygenase (HMOX), of which there are two isoforms, called HMOX1 and HMOX2. HMOX breaks down heme to form biliverdin, carbon monoxide, and iron. The porphyrias are a group of disorders, mainly inherited, in which there are defects in normal porphyrin and heme synthesis. The cardinal clinical features are cutaneous (due to the skin-damaging effects of excess deposited porphyrins) or neurovisceral attacks of pain, sometimes with weakness, delirium, seizures, and the like (probably due mainly to neurotoxic effects of ALA). The treatment of choice for the acute hepatic porphyrias is intravenous heme therapy, which repletes a critical regulatory heme pool in hepatocytes and leads to downregulation of hepatic ALA synthase, which is a biochemical hallmark of all forms of acute porphyria in relapse.",
Arsenic,1015663,"Arsenite exposure altered the expression of NMDA receptor and postsynaptic signaling proteins in rat hippocampus Abstract: Chronic arsenic exposure has an adverse effect on neurobehavioral function. Our previous study demonstrated an elevated arsenic level, ultra-structure changes and reduced NR2A gene expression in hippocampus, and impaired spatial learning in arsenite-exposed rats. The NMDA receptor and the postsynaptic signaling proteins CaMKII, postsynaptic density protein 95 (PSD-95), synaptic Ras GTPase-activating protein (SynGAP) and nuclear activated extracellular-signal regulated kinase (ERK1/2) play important roles in synaptic plasticity, learning and memory. We hypothesized that the above molecular expression changes may contribute to arsenic neurotoxicity. In present study, the expression of NMDA receptor and postsynaptic signaling proteins in hippocampus were evaluated in rats exposed to 0, 2.72, 13.6 and 68mg/L sodium arsenite for 3 months. Decreased protein expression of NR2A, PSD-95 and p-CaMKII ? in the hippocampus of arsenite-exposed rats was observed, while the expression of SynGAP, a negative regulator of Ras-MAPK activity, was increased when compared with the controls. Additionally, decreased p-ERK1/2 activity was found in the hippocampus of arsenite-exposed rats. These data suggest that altered expression of NMDA receptor complex and postsynaptic signaling proteins may explain arsenic-induced neurotoxicity.",
Arsenic,670830,"Effects of copper, cadmium, lead, and arsenic in a live diet on juvenile fish growth Abstract: The effects of diet-borne copper, cadmium, lead, and arsenic on juvenile fish were evaluated using a live diet consisting of the oligochaete Lumbriculus variegatus. In 30d exposures, no effects were observed on the growth and survival of rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas), and channel catfish (Ictalurus punctatus) fed diets contaminated with copper [130-310?g Cu·(g dm)?1], cadmium [90-540?g Cd·(g dm)?1], and lead [850-1000?g Pb·(g dm)?1]. However, rainbow trout growth was reduced in a dose-dependent manner for diets contaminated with arsenic [26-77?g As·(g dm)?1]. These effects of arsenic on fish growth were accompanied by slower feeding rate, reduced food conversion efficiency, liver cell abnormalities, and fecal matter changes suggestive of digestive effects, and occurred to a similar extent whether the diet was exposed to arsenate or arsenite. Effects from these dietary levels of arsenic, and the absence of effects from these dietary levels of metals, were generally consistent with literature reports using laboratory diets amended with toxicant salts. These results also indicated that reported growth effects on rainbow trout fed diets of invertebrates collected from mining-contaminated areas of the Clark Fork River (Montana, USA) or exposed in the laboratory to Clark Fork River sediments are likely more attributable to the arsenic than the metals in those diets.",
Arsenic,1348344,"Modulation of the arsenite-induced expression of stress proteins by reducing agents Abstract: We examined the effects of reducing agents on the expression of heat shock protein 27 (hsp27), alpha B crystallin, and hsp70 in C6 rat glioma cells in response to stress. Cells were exposed to arsenite (100 microM for 1 h) in the presence of dithiothreitol at various concentrations (0.03-2 mM), and the accumulation of all three proteins was markedly stimulated in cells that had been exposed to arsenite in the presence of a low concentration (0.03-0.1 mM) of dithiothreitol. Stimulation of these arsenite-induced responses was also observed in the presence of 0.1 mM 2-mercaptoethanol or 0.05 mM dithioerythritol. The enhanced expression of mRNAs for hsp27, alpha B crystallin and hsp70, as well as the prolonged activation of heat shock transcription factor 1 (HSF1), were also observed in cells that had been treated with arsenite in the presence of 0.05 mM dithiothreitol. The arsenite-inducible expression of the three proteins was completely suppressed when dithiothreitol was present at concentrations above 1 mM during the stress period, although delayed activation of the binding to a heat shock element (HSE) by phosphorylated HSF was observed in these cells. Exposure of cells first to arsenite for 1 h and then to dithiothreitol resulted in a very effective suppression of the arsenite-inducible responses, and the responses were inhibited even by a low concentration of dithiothreitol. These results suggest that the signal transduction pathway for the arsenite-induced expression of hsps involves at least two redox-sensitive steps: (i) a process that is stimulated by mild reducing power during the stress period; and (ii) a process that is followed by the activation of HSF and is very sensitive to suppression by a reducing agent.",
Arsenic,1339266,"Potential release of selected trace elements (As, Cd, Cu, Mn, Pb and Zn) from sediments in Cam River-mouth (Vietnam) under influence of pH and oxidation Abstract: Since contaminated river-bed sediments in the Cam River-mouth (Vietnam) are regularly dredged and disposed on land, an understanding of the influence of time, pH and oxidation on the leaching behavior of heavy metals (Cd, Cu, Mn, Pb and Zn) and arsenic is necessary for the management of these dredged materials. A 96 h pH(stat)-leaching test to examine the leaching behavior of elements at pre-set pH values (2, 4, 6, 8 (natural), 9 and 11) and a BCR 3-step extraction to clarify the element fractionation, were performed on a freshly-collected wet suboxic sediment and a dry oxidized sediment. All heavy metals and arsenic display a V-shaped pH-dependent leaching pattern with important releases at pHs 2 and 11. At the investigated pH values, the release of As, Mn, Pb and Zn from the oxidized sediment is slower and lower if compared with the suboxic sediment while the opposite trend is found for Cd and Cu at pHs 2-8. The transfer from the acid-soluble (exchangeable and carbonate-bound) fraction to the reducible (Fe and Mn hydr/oxide-bound) fraction is consistent with the lower leachability of As, Mn and Zn at pHs 2-8 and Pb at pHs 4-8 after oxidation, while the transfer from the oxidizable (organic matter and sulfide-bound) fraction to the reducible fraction relates to the higher leachability of Cd and Cu at pHs 2-8. The lower leachability of all elements at alkaline pHs 9-11 is due to lower leached concentration of organic matter from the oxidized sediment. Sulfides only play a minor role in controlling the leachability of heavy metals and arsenic.",
Arsenic,1070453,"Arsenic-Transformed Malignant Prostate Epithelia Can Convert Noncontiguous Normal Stem Cells into an Oncogenic Phenotype Abstract: Background: Cancer stem cells (CSCs) are likely critical to carcinogenesis, and, like normal stem cells (NSCs), are impacted by microenvironment. Malignant cells release extracellular factors modifying tumor behavior. Inorganic arsenic, a human carcinogen, over-produces CSCs in various model systems of carcinogenesis. Here, we determine if NSCs are influenced by nearby arsenic-transformed malignant epithelial cells (MECs) as a possible factor in arsenic associated CSC overabundance. Methods: Transwell non-contact co-culture allowed the study of the effects of non-contiguous, arsenic-transformed prostate MECs on the isogenic human prostate NSC line, WPE-stem. Cancer phenotype was assessed by secreted MMPs, invasiveness, colony formation and spheroid formation. Gene expression was assessed at the protein (western blot) or mRNA (RT-PCR) levels. Results: Non-contact co-culture of MECs and NSCs rapidly (? 3 weeks) caused hyper-secretion of MMPs and marked suppression of the tumor suppressor gene PTEN in NSCs. NSCs co-cultured with MECs also showed increased invasiveness and clonogenicity and formed more free-floating spheroids and highly branched ductal-like structures in Matrigel, all typical for CSCs. MEC co-culture caused dysregulated self-renewal and differentiation-related gene expression patterns and epithelial-to-mesenchymal transition in NSCs consistent with acquired cancer phenotype. Interleukin-6, a cytokine involved in tumor microenvironment control, was hyper-secreted by MECs and interleukin-6 exposure duplicated several responses in NSCs of conversion to CSCs via MEC co-culture (MMP hyper-secretion, decreased PTEN, etc.). Conclusions: These results indicate that arsenic-transformed MECs recruit nearby NSCs into a cancer phenotype thereby potentially increasing CSC number. This may be a factor in arsenic-induced CSC overabundance seen in multiple model systems.",
Arsenic,1021445,"Human exposure to arsenic through foodstuffs cultivated using arsenic contaminated groundwater in areas of West Bengal, India Abstract: The widespread incidence of chronic arsenicosis in the Bengal Delta has led to intensive research on arsenic (As) enrichment in groundwater as well as accumulation in foodstuffs, as there are potential health risks associated with exposure to As from both sources. This study deals with human As exposure through the drinking of groundwater, consumption of locally grown foodstuffs (e.g., crops and vegetables) and cooked food in Nadia district, West Bengal. Groundwater and foodstuffs were collected and analyzed with FI-HG-AAS to estimate the total As content. Urine samples collected from human subjects were analyzed to assess the As exposure. Two major crops, boro and aman rice, showed a considerable amount of As, with mean values of 194 and 156 ?g kg(-1), respectively. Significant levels of As were also found in other common crops and vegetables cultivated in this area (for example, the mean As in Arum and radish was 780 and 674 ?g kg(-1), respectively). Total intake of As from foodstuffs by adults (560 ?g day(-1)) and children (393 ?g day(-1)) in the area was found to be at alarming levels. Arsenic exposure was demonstrated by the presence of As in urine (ranging between 154 and 276 ?g L(-1)), with overall As retention of 50-60 %. The results of this study further indicate the potential risk of As exposure to local inhabitants through the food chain which is associated with continuous consumption of As-contaminated foodstuffs. Therefore, more action needs to be taken to control the contamination pathways (such as the water-soil-crop system) to protect humans from continuous ingestion of As through foodstuffs.",
Arsenic,2279489,"Multi-technique quantitative analysis and socioeconomic considerations of lead, cadmium, and arsenic in children's toys and toy jewelry Abstract: A wide spectrum and large number of children's toys and toy jewelry items were purchased from both bargain and retail vendors and analyzed for arsenic, cadmium, and lead metal content using multiple analytical techniques, including flame and furnace atomic absorption spectroscopy as well as X-ray fluorescence spectroscopy. Particularly dangerous for young children, metal concentrations in toys/toy jewelry were assessed for compliance with current Consumer Safety Product Commission (CPSC) regulations (F963-11). A conservative metric involving multiple analytical techniques was used to categorize compliance: one technique confirmation of metal in excess of CPSC limits indicated a &quot;suspect&quot; item while confirmation on two different techniques warranted a non-compliant designation. Sample matrix-based standard addition provided additional confirmation of non-compliant and suspect products. Results suggest that origin of purchase, rather than cost, is a significant factor in the risk assessment of these materials with 57% of toys/toy jewelry items from bargain stores non-compliant or suspect compared to only 15% from retail outlets and 13% if only low cost items from the retail stores are compared. While jewelry was found to be the most problematic product (73% of non-compliant/suspect samples), lead (45%) and arsenic (76%) were the most dominant toxins found in non-compliant/suspect samples. Using the greater Richmond area as a model, the discrepancy between bargain and retail children's products, along with growing numbers of bargain stores in low-income and urban areas, exemplifies an emerging socioeconomic public health issue.",
Arsenic,1352459,"Arsenic exposure and health effects IV Human cell models for arsenic carcinogenicity and toxicity: Transformation and genetic susceptibility Abstract: Humans are more sensitive to arsenic compounds than are rodents by at least an order of magnitude. This is also true on the cellular level. The lack of an arsenite-inducible tolerance mechanism in human cells may partly account for their sensitivity. In addition, inter-individual variability in sensitivity to arsenic is well known. It is therefore important to study the effects of arsenic compounds on human cells. We have found that extremely low and completely nontoxic concentrations of arsenite (0.1 nM) can transform human osteosarcoma (HOS) cells to anchorage-independence, a marker for tumorigenicity. The transformation is seen only after extensive growth (similar to8 weeks) in the presence of arsenite. HOS transformation will be an important system with which to study the mechanism of arsenite carcinogenicity. We have also started a study of genetic diversity by measuring the sensitivities of 14 lymphoblast lines derived from normal human donors. We show that growth inhibition by arsenite differs significantly in different lymphoblast lines, and that the differences are not related to the growth rates of the lymphoblasts. By comparing arsenite metabolism, uptake, efflux, and specific gene expression between the most sensitive and most resistant lines, we may be able to identify genes of importance in arsenic sensitivity.",
Arsenic,1508665,"The discovery of stromatolites developing at 3570 m above sea level in a high-altitude volcanic lake Socompa, Argentinean Andes Abstract: We describe stromatolites forming at an altitude of 3570 m at the shore of a volcanic lake Socompa, Argentinean Andes. The water at the site of stromatolites formation is alkaline, hypersaline, rich in inorganic nutrients, very rich in arsenic, and warm (20-24°C) due to a hydrothermal input. The stromatolites do not lithify, but form broad, rounded and low-domed bioherms dominated by diatom frustules and aragonite micro-crystals agglutinated by extracellular substances. In comparison to other modern stromatolites, they harbour an atypical microbial community characterized by highly abundant representatives of Deinococcus-Thermus, Rhodobacteraceae, Desulfobacterales and Spirochaetes. Additionally, a high proportion of the sequences that could not be classified at phylum level showed less than 80% identity to the best hit in the NCBI database, suggesting the presence of novel distant lineages. The primary production in the stromatolites is generally high and likely dominated by Microcoleus sp. Through negative phototaxis, the location of these cyanobacteria in the stromatolites is controlled by UV light, which greatly influences their photosynthetic activity. Diatoms, dominated by Amphora sp., are abundant in the anoxic, sulfidic and essentially dark parts of the stromatolites. Although their origin in the stromatolites is unclear, they are possibly an important source of anaerobically degraded organic matter that induces in situ aragonite precipitation. To the best of our knowledge, this is so far the highest altitude with documented actively forming stromatolites. Their generally rich, diverse and to a large extent novel microbial community likely harbours valuable genetic and proteomic reserves, and thus deserves active protection. Furthermore, since the stromatolites flourish in an environment characterized by a multitude of extremes, including high exposure to UV radiation, they can be an excellent model system for studying microbial adaptations under conditions that, at least in part, resemble those during the early phase of life evolution on Earth.",
Arsenic,2345706,"Desorption of metals from aquifer soils during infiltration of low ionic strength water by pH effect Abstract: Primary and trace metals from S400 samples are higher than that from S700 because the size of S400 is smaller than one of S700. The effects of solution chemistry, i.e., ionic strength and pH, on metal immobilization were evaluated via batch desorption equilibrium experiments for aquifer soils during infiltration of low ionic strength water. For S400 and S700, cumulative desorption amount of Ca is, respectively 2050 and 1900 mg/kg-soil with 12 times extraction at 58 mg/L of TDS water at pH = 4. It was found that desorption of Ca, Mg and Ba decreases with increasing pH. For S400 and S700, cumulative desorption amount of As is 0.9 mg/kg-soil with 15 times extraction at 58 mg/L of TDS water at pH = 9. On the contrary, desorption of As was found to increase slightly with increasing solution pH, although the effect of pH is not as great as that for the other metals. This effect was offset by the less dissolution of CaCO3 at higher pH, which reduced release of carbonate associated arsenic.",
Arsenic,1508711,"Impact of arsenic on uptake and bio-accumulation of antimony by arsenic hyperaccumulator Pteris vittata Abstract: Individual uptake of As and Sb species in Pteris vittata have been investigated, but little information is available how uptake is affected if both metalloids are simultaneously present in different amounts. We investigated the uptake of antimony and its speciation in Pteris vittata cultivated in quartz substrate with, versus without, co-contamination with arsenic and a contaminated soil for 7 weeks. Applying HPLC-ICP-MS technique Sb(V), Sb(III), As(III), and As(V) could be identified as main species in aqueous extracts of roots and fronds with up to 230 mg kg(-1) of total Sb in the roots. Adding increasing amounts of As to the quartz substrate resulted in increasing uptake of Sb. In contrast to As, which is readily transferred to the fronds, Sb is primarily accumulated in the roots with Sb(V) being the dominant species (&gt;90% of Sb). The addition of As doesn't result in enhanced translocation of Sb into the fronds.",
Arsenic,1021367,"Role of NADPH oxidase in arsenic-induced reactive oxygen species formation and cytotoxicity in myeloid leukemia cells Abstract: Arsenic has played a key medicinal role against a variety of ailments for several millennia, but during the past century its prominence has been displaced by modern therapeutics. Recently, attention has been drawn to arsenic by its dramatic clinical efficacy against acute promyelocytic leukemia. Although toxic reactive oxygen species (ROS) induced in cancer cells exposed to arsenic could mediate cancer cell death, how arsenic induces ROS remains undefined. Through the use of gene expression profiling, interference RNA, and genetically engineered cells, we report here that NADPH oxidase, an enzyme complex required for the normal antibacterial function of white blood cells, is the main target of arsenic-induced ROS production. Because NADPH oxidase enzyme activity can also be stimulated by phorbol myristate acetate, a synergism between arsenic and the clinically used phorbol myristate acetate analog, bryostatin 1, through enhanced ROS production can be expected. We show that this synergism exists, and that the use of very low doses of both arsenic and bryostatin 1 can effectively kill leukemic cells. Our findings pinpoint the arsenic target of ROS production and provide a conceptual basis for an anticancer regimen.",
Arsenic,1025844,"Characterization of arsenic (V) and arsenic (III) in water samples using ammonium molybdate and estimation by graphite furnace atomic absorption spectroscopy Abstract: Arsenic (V) is known to form heteropolyacid with ammonium molybdate in acidic aqueous solutions, which can be quantitatively extracted into certain organic solvents. In the present work, 12-molybdoarsenic acid extracted in butan-1-ol is used for quantification of As (V). Total arsenic is estimated by converting arsenic (III) to arsenic (V) by digesting samples with concentrated nitric acid before extraction. Concentration of As (III) in the sample solutions could be calculated by the difference in total arsenic and arsenic (V). The characterization of arsenic was carried out by GFAAS using Pd as modifier. Optimization of the experimental conditions and instrumental parameters was investigated in detail. Recoveries of (90-110%) were obtained in the spiked samples. The detection limit was 0.2 microg l(-1). The proposed method was successfully applied for the determination of trace amount of arsenic (III) and arsenic (V) in process water samples.",
Arsenic,628394,"Metals, toxicity and oxidative stress Abstract: Metal-induced toxicity and carcinogenicity, with an emphasis on the generation and role of reactive oxygen and nitrogen species, is reviewed. Metal-mediated formation of free radicals causes various modifications to DNA bases, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Lipid peroxides, formed by the attack of radicals on polyunsaturated fatty acid residues of phospholipids, can further react with redox metals finally producing mutagenic and carcinogenic malondialdehyde, 4-hydroxynonenal and other exocyclic DNA adducts (etheno and/or propano adducts). Whilst iron (Fe), copper (Cu), chromium (Cr), vanadium (V) and cobalt (Co) undergo redox-cycling reactions, for a second group of metals, mercury (Hg), cadmium (Cd) and nickel (Ni), the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. Arsenic (As) is thought to bind directly to critical thiols, however, other mechanisms, involving formation of hydrogen peroxide under physiological conditions, have been proposed. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. Common mechanisms involving the Fenton reaction, generation of the superoxide radical and the hydroxyl radical appear to be involved for iron, copper, chromium, vanadium and cobalt primarily associated with mitochondria, microsomes and peroxisomes. However, a recent discovery that the upper limit of ""free pools"" of copper is far less than a single atom per cell casts serious doubt on the in vivo role of copper in Fenton-like generation of free radicals. Nitric oxide (NO) seems to be involved in arsenite-induced DNA damage and pyrimidine excision inhibition. Various studies have confirmed that metals activate signalling pathways and the carcinogenic effect of metals has been related to activation of mainly redox-sensitive transcription factors, involving NF-kappaB, AP-1 and p53. Antioxidants (both enzymatic and non-enzymatic) provide protection against deleterious metal-mediated free radical attacks. Vitamin E and melatonin can prevent the majority of metal-mediated (iron, copper, cadmium) damage both in vitro systems and in metal-loaded animals. Toxicity studies involving chromium have shown that the protective effect of vitamin E against lipid peroxidation may be associated rather with the level of non-enzymatic antioxidants than the activity of enzymatic antioxidants. However, a very recent epidemiological study has shown that a daily intake of vitamin E of more than 400 IU increases the risk of death and should be avoided. While previous studies have proposed a deleterious pro-oxidant effect of vitamin C (ascorbate) in the presence of iron (or copper), recent results have shown that even in the presence of redox-active iron (or copper) and hydrogen peroxide, ascorbate acts as an antioxidant that prevents lipid peroxidation and does not promote protein oxidation in humans in vitro. Experimental results have also shown a link between vanadium and oxidative stress in the etiology of diabetes. The impact of zinc (Zn) on the immune system, the ability of zinc to act as an antioxidant in order to reduce oxidative stress and the neuroprotective and neurodegenerative role of zinc (and copper) in the etiology of Alzheimer's disease is also discussed. This review summarizes recent findings in the metal-induced formation of free radicals and the role of oxidative stress in the carcinogenicity and toxicity of metals.",
Arsenic,710841,"Arsenic promotes angiogenesis in vitro via a heme oxygenase-1-dependent mechanism Abstract: Angiogenesis and vessel remodeling are fundamental to the pathogenesis of a number of diseases caused by environmental arsenic exposure, including tumorigenesis and cardiovascular diseases. Arsenic (AsIII) has been shown to stimulate angiogenesis and vascular remodeling in vivo. However, the exact molecular mechanisms accounting for arsenic-induced angiogenesis are not clear. The present study investigates the role of heme oxygenase-1 (HO-1) in sodium arsenite-mediated angiogenesis in vitro. Transwell assay, three-dimensional Matrigel assay, RT-PCR, ELISA and immunoblotting were used to determine cell migration, vascular tube formation, mRNA and protein expression. Chromatin immunoprecipitation and luciferase assay were applied to examine the DNA binding with protein and HO-1 transcriptional activity. Here, we report that low concentrations of arsenite (0.1-1 muM) stimulated cell migration and vascular tube formation in human microvascular endothelial cells (HMVEC). Arsenite induced HO-1 mRNA and protein expression. Knock down of HO-1 expression decreased arsenite-induced VEGF expression, cell migration, and tube formation. We showed that arsenite promoted dissociation of Bach1 (a transcriptional repressor) from the HO-1 enhancers and increased Nrf2 binding to these elements. Site directed mutagenesis assay identified that Bach1 cysteine residues 557 and 574 were essential for the induction of HO-1 gene in response to arsenite. These findings demonstrate a role for HO-1 in arsenite-mediated angiogenesis in vitro.",
Arsenic,732052,"Enhanced expression of multidrug resistance-associated protein 2 and reduced expression of aquaglyceroporin 3 in an arsenic-resistant human cell line Abstract: Arsenic-resistant cells (R15), derived from a human lung adenocarcinoma cell line (CL3), were 10-fold more resistant to sodium arsenite (As(III)). Because R15 cells accumulated less arsenic than parental CL3 cells, this arsenic resistance may be due to higher efflux and/or lower uptake of As(III). We therefore compared expression of the multidrug resistance-associated proteins MRP1, MRP2, and MRP3 in these two cell lines. MRP2 expression was 5-fold higher in R15 cells than in CL3 cells, whereas MRP1 and MRP3 expression levels were similar. Furthermore, verapamil and cyclosporin A, inhibitors of multidrug resistance transporters, significantly reduced the efflux of arsenic from R15. Thus, increased arsenic extrusion by MRP2 may contribute to arsenic resistance in R15 cells. We also examined the expression of several aquaglyceroporins (AQPs), which mediate As(III) uptake by cells. Little AQP7 or AQP9 mRNA was detected by reverse transcription-PCR in either cell line, whereas AQP3 mRNA expression was 2-fold lower in R15 cells than in CL3 cells. When AQP3 expression in CL3 cells was knocked down by RNA interference, CL3 cells accumulated less arsenic and became more resistant to As(III). Conversely, overexpression of AQP3 in human embryonic kidney 293T cells increased arsenic accumulation, and the cells were more susceptible to As(III) than 293T cells transfected with vector alone. These results suggest that AQP3 is involved in As(III) accumulation. Taken together, our results suggest that enhanced expression of MRP2 and lower expression of AQP3 are responsible for lower arsenic accumulation in arsenic-resistant R15 cells.",
Arsenic,1508532,"Temporal trends (1989-2011) in levels of mercury and other heavy metals in feathers of fledgling great egrets nesting in Barnegat Bay, NJ Abstract: There is an abundance of data for levels of metals from a range of species, but relatively few long-term time series from the same location. In this paper I examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers from fledgling great egrets (Ardea alba) collected at nesting colonies in Barnegat Bay, New Jersey from 1989 to 2011. The primary objectives were to test the null hypotheses that (1) There were no temporal differences in metal levels in feathers of fledgling great egrets, and (2) Great egrets nesting in different areas of Barnegat Bay (New Jersey) did not differ in metal levels. There were significant yearly variations in levels of all heavy metals in feathers of fledgling great egret, but levels decreased significantly from 1989 to 2011 only for lead (1470 ppb to 54.3 ppb), cadmium (277 ppb to 30.5 ppb), and manganese (only since 1996; 2669 ppb to 329 ppb). Although mercury levels decreased from 2003-2008 (6430 ppb to 1042 ppb), there was no pattern before 2003, and levels increased after 2008 to 2610 ppb in 2011. Lead, cadmium, chromium, manganese and mercury were higher in feathers from great egrets nesting in the northern part of the bay, and selenium was highest in feathers from mid-bay. The lack of a temporal decline in mercury levels in feathers of great egrets is cause for concern, since the high levels in feathers from some years (means as high as 6430 ppb) are in the range associated with adverse effects (5000 ppb for feathers).",
Arsenic,2337129,"ASSESSMENT OF DISTILLATE WATER QUALITY PARAMETERS PRODUCED BY SOLAR STILL FOR POTABLE USAGE Abstract: In this study, a few field experiments were conducted on a simple solar still and water quality analyses were done in laboratory to check the contaminants removal efficiency from raw water samples. A few water quality parameters such as pH, redox, electrical conductivity (EC), salinity, total dissolved solids (TDS), Escherichia coli and arsenic for the feed (before distillation) and product water (after distillation by a solar still) were obtained. A wide range of water samples (e.g. seawater, pond water, and arsenic contaminated groundwater) were collected from various locations in Malaysia and Bangladesh. A few synthetic saline water samples (e.g. 1, 2, 3 and 5% salt) were also prepared. The values of pH (6.5-7.5), redox (100-200 mV), EC (&lt; 750 mu S/cm) of the product water were found within the standard ranges. The average removal efficiencies of more than 24 and 99% were obtained from repetitive tests run on salinity and arsenic, respectively. The still was also successful in removing pathogenic bacteria by more than 80%. These obtained parameters of the product water were then compared with various drinking water standards and found that most of the values obtained were within the acceptable ranges provided by the standards. Finally, it is concluded that the solar still is able to produce potable water and can be installed to remove the water scarcity in coastal and arid regions.",
Arsenic,1337674,"SMN Deficiency Reduces Cellular Ability to Form Stress Granules, Sensitizing Cells to Stress Abstract: Spinal Muscular Atrophy (SMA) is a neurodegenerative disease that is caused by deletion of the SMN (Survival of Motor Neuron) gene. The SMN protein is essential for cell survival and co-localized with TIA-1/R and G3BP, two characteristic markers of stress granules (SGs). To further study the SMN function in stress granules and in response to stress, we generated stable cell lines with SMN knockdown. Our data indicate that suppression of SMN drastically reduces cellular ability to form stress granules in response to stress treatment. In addition, we show that SMN deficiency sensitizes cells to sodium arsenite and H(2)O(2), two well-known stress inducers, leading to cell death at a much lower concentration of inducers in SMN knockdown cells than in control cells. Interestingly, the cell death is correlated with formation of stress granules, suggesting that involvement of SMN in formation of stress granules may play an important role in cell survival. Furthermore, rescue of SGs formation by overexpression of G3BP can reverse the defective formation of stress granules and results in partial abrogation of cell death against SMN deficiency. We deduce that modulation of stress response may be useful for potential SMN treatment.",
Arsenic,1350143,"Regulation of System A amino acid transport in L6 rat skeletal muscle cells by insulin, chemical and hyperthermic stress Abstract: In this study we have investigated the effects of insulin, chemical and hyperthermic stresses upon the activity of the System A amino acid transporter in L6 rat muscle cells. Uptake of alpha-methyl-aminoisobutyric acid (Me-AIB), a non-metabolisable System A substrate, was increased by between 50% and 80% when muscle cells were exposed to a maximally effective concentration of insulin (100 nM), sodium arsenite (ARS, 0.5 mM) or a 42 degrees C heat shock (HS). The observed activation in System A in response to all three stimuli was maximal within 20 min and in the case of insulin and ARS primarily involved an increase in the Vmax of System A transport. In contrast, HS induced significant increases in both Vmax and Km of System A transport suggesting that hyperthermic stress may activate System A by a mechanism distinct from that mediating the effects of insulin and ARS. The hormonal stimulation of System A was blocked by the phosphoinositide 3-kinase (PI3k) inhibitor, wortmannin, but not by rapamycin or PD 98059 which respectively inhibit the mTOR and classical MAP kinase pathways. Exposure of L6 cells to ARS, but not HS, caused a 4.7-fold stimulation in MAPKAP-K2 activity that was blocked by SB 203580, a specific inhibitor of the stress activated protein kinase SAPK2/p38. However, neither SB 203580, rapamycin nor wortmannin were able to suppress the ARS- or HS-induced stimulation in System A transport. In summary, our results demonstrate that activity of the System A transporter can be rapidly upregulated in response to hormonal and stress stimuli through changes in the transport kinetics of the System A carrier. Our data show that whilst the hormonal response is PI3k dependent, the signalling mechanisms which instigate changes in System A activity in response to chemical or hyperthermic stress do not appear to involve PI3k or components of the mTOR, p42/p44 MAP kinase or SAPK2/p38 signalling pathways.",
Arsenic,1392399,"Effect of Subchronic Arsine Inhalation on Immune Function and Host Resistance Abstract: The effect of arsine (7784421) on immune function and host resistance was studied in mice. Female B6C3F1-mice were exposed to 0.5, 2.5, or 5.0 parts per million (ppm) arsine 6 hours/day for 14 days. Selected mice were killed after the last exposure. Host resistance against inoculation with melanoma tumor cells, Listeria-monocytogenes, influenza, and Plasmodium-yoelii was evaluated in other mice. Arsine induced concentration related decreases in absolute and relative spleen weights. Concentration dependent decreases in splenic rubricytes and percentage lymphocytes also occurred; however, total cellularity was not significantly affected. The relative numbers of T-lymphocytes were significantly decreased in a concentration dependent manner. The relative number of B-lymphocytes was significantly decreased only by 5.0ppm arsine. The proliferative responses of splenic lymphocytes were not significantly affected when expressed on a per lymphocyte basis. Arsine did not significantly affect natural killer cell or cytotoxic T-cell function. Host resistance to challenge with melanoma tumor cells or influenza was not affected. Host resistance to Listeria and Plasmodium was impaired. Arsine concentrations above 2.5ppm significantly increased the plaque forming cell response to sheep red blood cells. The authors suggest that the spleen is a target organ for arsine. Since some of the changes were induced by concentrations only ten times the current threshold limit value, additional studies should be conducted to determine if arsine represents an occupational health hazard.",
Arsenic,1070467,"Survival, reproduction, and arsenic body burdens in Chironomus riparius exposed to arsenate and phosphate Abstract: Despite the increasing awareness of arsenic (As) contamination in surface waters worldwide, little is known about how As alone and in the presence of other chemicals affects aquatic insects. Larvae of Chironomus riparius were exposed in a laboratory investigation to factorial combinations of 0, 0.13, 2.0, 5.3, and 13?molAsl(-1) and 0, 0.15, and 15?molPO(4)l(-1) throughout development from first instar to pupal emergence. The time between male and female emergence increased from 1.8±0.17days to 2.9±0.34days with exposure at higher As levels. The highest As exposure also decreased the number of eggs per egg mass, which may affect population maintenance. For these parameters, there was no effect from PO(4), and no interaction between As and PO(4). Total As determination of larval and adult tissues was conducted using Hydride Generated Atomic Absorption Spectroscopy (HGAAS) and revealed concentrations ranging from 2.48±0.363 to 30.5±0.473?g/g and 1.03±0.286 to 8.97±0.662?g/g, respectively, indicating elimination of approximately 72% of total As body burdens between the fourth instar and adult stages. There was no effect of PO(4), indicating PO(4) does not alter uptake of As in C. riparius. The potential for movement of As to terrestrial systems exists, though trophic transfer may be more likely during the aquatic larval stage.",
Arsenic,1240339,"Extremophilic Acinetobacter Strains from High-Altitude Lakes in Argentinean Puna: Remarkable UV-B Resistance and Efficient DNA Damage Repair Abstract: High-Altitude Andean Lakes (HAAL) of the South American Andes are almost unexplored ecosystems of shallow lakes. The HAAL are recognized by a remarkably high UV exposure, strong changes in temperature and salinity, and a high content of toxic elements, especially arsenic. Being exposed to remarkably extreme conditions, they have been classified as model systems for the study of life on other planets. Particularly, Acinetobacter strains isolated from the HAAL were studied for their survival competence under strong UV-B irradiation. Clinical isolates, Acinetobacter baumannii and Acinetobacter johnsonii, served as reference material. Whereas the reference strains rapidly lost viability under UV-B irradiation, most HAAL-derived strains readily survived this exposure and showed less change in cell number after the treatment. Controls for DNA repair activity, comparing dark repair (DR) or photo repair (PR), gave evidence for the involvement of photolyases in the DNA repair. Comparative measurements by HPLC-mass spectrometry detected the number of photoproducts: bipyrimidine dimers under both PR and DR treatments were more efficiently repaired in the HAAL strains (up to 85 % PR and 38 % DR) than in the controls (31 % PR and zero DR ability). Analysis of cosmid-cloned total genomic DNA from the most effective DNA-photorepair strain (Ver3) yielded a gene (HQ443199) encoding a protein with clear photolyase signatures belonging to class I CPD-photolyases. Despite the relatively low sequence similarity of 41 % between the enzymes from Ver3 and from E. coli (PDB 1DNPA), a model-building approach revealed a high structural homology to the CPD-photolyase of E. coli.",
Arsenic,1018405,"The inhibitory effect of selenium on induction of tetraploidy by dimethylarsinic acid in Chinese hamster cells Abstract: Arsenic is a human carcinogen. On the other hand, selenium supplementation can inhibit induction of carcinogenesis by chemical carcinogens. The effect of selenium compounds on the cytotoxicity of dimethylarsinic acid (DMA) and on the induction of tetraploidy by DMA were studied using Chinese hamster V79 cells. Two selenium compounds were tested, sodium selenite and trimethylselenonium iodide (TMSeI). Trimethylselenonium is a major excretory product of selenite metabolism. The cytotoxicity of sodium selenite was 1000-fold greater than that of TMSeI. The cytotoxicity of DMA was about the same as that of TMSeI. The mitotic index for DMA administration was increased by these selenium compounds at low concentrations and decreased by them at high concentrations. The tetraploid index for DMA decreased with increasing concentrations of these selenium compounds. Tetraploidy is a form of aneuploidy, and aneuploidy is known to induce carcinogenesis. The finding that selenium inhibited induction of tetraploidy by DMA may yield clues to the role of selenium in the chemoprevention of carcinogenesis by chemical carcinogens.",
Arsenic,1348742,TRACE ANALYSIS OF ULTRAPURE ARSENIC AND SELENIUM BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY Abstract: ,
Arsenic,2298719,"Business model innovation in the water sector in developing countries Abstract: Various technologies have been deployed in household devices or micro-water treatment plants for mitigating fluoride and arsenic, and thereby provide safe and affordable drinking water in low-income countries. While the technologies have improved considerably, organizations still face challenges in making them financially sustainable. Financial sustainability questions the business models behind these water technologies. This article makes three contributions to business models in the context of fluoride and arsenic mitigation. Firstly, we describe four business models: A) low-value devices given away to people living in extreme poverty, B) high-value devices sold to low-income customers, C) communities as beneficiaries of micro-water treatment plants and D) entrepreneurs as franchisees for selling water services and highlight the emergence of hybrid business models. Secondly, we show current business model innovations such as cost transparency &amp; cost reductions, secured &amp; extended water payments, business diversification and distribution channels. Thirdly, we describe skills and competencies as part of capacity building for creating even more business model innovations. Together, these three contributions will create more awareness of the role of business models in scaling-up water treatment technologies.",
Arsenic,1704146,"Comparison of Two In Vitro Extraction Protocols for Assessing Metals' Bioaccessibility Using Dust and Soil Reference Materials Abstract: The bioaccessibility of arsenic, cadmium, chromium, copper, lead, nickel, and zinc in four National Institute of Standards and Technology (NIST) standard reference materials and two Canadian dust samples as determined using the Solubility/Bioavailability Research Consortium (SBRC) in vitro procedure ranged from a low of 1.8% for chromium in standard reference material NIST 2711 to a high of 95.2% for cadmium in NIST 2584. The SBRC data were compared to data generated using a modified EN-71 Toy Safety protocol conducted at two different laboratories. Results for the two extraction methods compared well with differences between the means (SBRC vs. modified EN-71) generally less than 10% for the majority of the metals. These differences between the two extraction methods were negligible compared to variability caused by (a) the inherent heterogeneity of typical house dust samples and (b) differences in ICP-MS analytical approaches employed in the different laboratories. Results indicate that the modified EN-71 method is useful and appropriate as a relatively simple, rapid, and reproducible screening test for estimating metals' bioaccessibility in soil and dust samples.",
Arsenic,1326907,"Cyclooxygenase-2 induction by arsenite is through a nuclear factor of activated T-cell-dependent pathway and plays an antiapoptotic role in Beas-2B cells Abstract: Arsenite is a well known metalloid human carcinogen, and epidemiological evidence has demonstrated its association with the increased incidence of lung cancer. However, the mechanism involved in its lung carcinogenic effect remains obscure. The current study demonstrated that exposure of human bronchial epithelial cells (Beas-2B) to arsenite resulted in a marked induction of cyclooxygenase (COX)-2, an important mediator for inflammation and tumor promotion. Exposure of the Beas-2B cells to arsenite also led to significant transactivation of nuclear factor of activated T-cells (NFAT), but not activator protein-1 (AP-1) and NFkappaB, suggesting that NFAT, rather than AP-1 or NFkappaB, is implicated in the responses of Beas-2B cells to arsenite exposure. Furthermore, we found that inhibition of the NFAT pathway by either chemical inhibitors, dominant negative mutants of NFAT, or NFAT3 small interference RNA resulted in the impairment of COX-2 induction and caused cell apoptosis in Beas-2B cells exposed to arsenite. Site-directed mutation of two putative NFAT binding sites between-111 to +65 in the COX-2 promoter region eliminated the COX-2 transcriptional activity induced by arsenite, confirming that those two NFAT binding sites in the COX-2 promoter region are critical for COX-2 induction by arsenite. Moreover, knockdown of COX-2 expression by COX-2-specific small interference RNA also led to an increased cell apoptosis in Beas-2B cells upon arsenite exposure. Together, our results demonstrate that COX-2 induction by arsenite is through NFAT3-dependent and AP-1- or NFkappaB-independent pathways and plays a crucial role in antagonizing arsenite-induced cell apoptosis in human bronchial epithelial Beas-2B cells.",
Arsenic,1353251,"Chelating Effect of Leek (Allium tuberosum Rottler ex Sprengel) Containing Chlorophyll on Cd, Pb, and As Abstract: ",
Arsenic,1022133,"Induction of cyclin D1 by arsenite and UVB-irradiation in human keratinocytes Abstract: Arsenic is an environmental pollutant with carcinogenic properties that is found in many regions of the world but that poses a health risk primarily in economically disadvantaged areas. In these areas, arsenic ingestion affects various tissues, especially skin in which it acts as a comutagen with the ultraviolet component of solar radiation. Both epidemiological and experimental evidence indicates that arsenic and ultraviolet radiation act on signaling pathways that effect the expression of cyclin D1. We have previously employed an in vitro model system of human epidermal keratinocytes to study the effects of submicromolar concentrations of sodium arsenite on cyclin D1 expression. Here, we employed this system to demonstrate concordant cyclin D1-related induction profiles of ultraviolet B radiation and arsenite using cDNA microarray analysis. We also show that both of these agents act epigenetically to bring about demethylation of the cyclin D1 promoter.",
Arsenic,1644868,"Characterization of shallow groundwater quality in the Lower St. Johns River Basin: a case study Abstract: Characterization of groundwater quality allows the evaluation of groundwater pollution and provides information for better management of groundwater resources. This study characterized the shallow groundwater quality and its spatial and seasonal variations in the Lower St. Johns River Basin, Florida, USA, under agricultural, forest, wastewater, and residential land uses using field measurements and two-dimensional kriging analysis. Comparison of the concentrations of groundwater quality constituents against the US EPA's water quality criteria showed that the maximum nitrate/nitrite (NO x ) and arsenic (As) concentrations exceeded the EPA's drinking water standard limits, while the maximum Cl, SO 4 (2?-) , and Mn concentrations exceeded the EPA's national secondary drinking water regulations. In general, high kriging estimated groundwater NH 4 (+) concentrations were found around the agricultural areas, while high kriging estimated groundwater NO x concentrations were observed in the residential areas with a high density of septic tank distribution. Our study further revealed that more areas were found with high estimated NO x concentrations in summer than in spring. This occurred partially because of more NO x leaching into the shallow groundwater due to the wetter summer and partially because of faster nitrification rate due to the higher temperature in summer. Large extent and high kriging estimated total phosphorus concentrations were found in the residential areas. Overall, the groundwater Na and Mg concentration distributions were relatively more even in summer than in spring. Higher kriging estimated groundwater As concentrations were found around the agricultural areas, which exceeded the EPA's drinking water standard limit. Very small variations in groundwater dissolved organic carbon concentrations were observed between spring and summer. This study demonstrated that the concentrations of groundwater quality constituents varied from location to location, and impacts of land uses on groundwater quality variation were profound.",
Arsenic,1579250,"Sources and methods of determination of arsenic compounds in environmental samples Abstract: The article is a review of information available in literature about arsenic and its compounds. The paper characterizes forms of arsenic that can be found in the environment, main chemical and physical transformations it undergoes, application of arsenic in industry and agriculture, dangers associated with arsenic contamination and its toxicity for humans and the environment. Natural and artificial sources of arsenic are discussed. Final part presents fractionating of arsenic in detail, as well as main methods of arsenic determination in the laboratory.",
Arsenic,1032483,"Inhibition of metabolic coupling by metals Abstract: Several metals were evaluated in cell cultures for their ability to inhibit metabolic coupling, the intercellular transfer of low-molecular-weight metabolites by directly connecting gap junctions. To monitor inhibition of metabolic coupling, wild-type Chinese hamster V79 cells proficient in metabolism of 6-thioguanine (6-TG) were cocultured with mutant V79 cells unable to metabolize 6-TG to its toxic metabolite (6-TG-resistant cells). In the presence of 6-TG, inhibition of metabolic coupling by the metals was manifested as increased recovery of 6-TG-resistant cells compared to recovery in untreated cocultures. The toxic metal compounds, arsenic(V) acid, mercury(II) chloride, lead(II) acetate, and nickel(II) chloride, significantly (p less than .05) increased recovery of 6-TG-resistant cells at concentrations that did not alter cell survival. However, because the increased recovery observed with nickel showed no concentration dependence, its importance may be negligible. Cadmium chloride increased 6-TG-resistant cell recovery only at a toxic concentration, and zinc sulfate failed to increase recovery. These data demonstrate that some metal compounds inhibit metabolic coupling, and suggest that inhibition of junctional communication should be further evaluated as a potential mechanism of toxicity of some metals.",
Arsenic,1794748,"Arsenic movement and traces in the groundwater from the Hetao area, Inner Mongolia Abstract: ",
Arsenic,627964,"Neurosensory effects of chronic human exposure to arsenic associated with body burden and environmental measures Abstract: Exposure to arsenic in drinking water is known to produce a variety of health problems, including peripheral neuropathy. Auditory, visual and somatosensory impairment have been reported in Mongolian farmers living in the Yellow River Valley, where drinking water is contaminated by arsenic. In the present study, sensory tests, including pinprick and vibration thresholds, were administered to 320 residents with well-water arsenic levels, ranging from non-detectable to 690 microg/L. Vibration thresholds in the second and fifth fingers of both hands were measured using a vibrothesiometer. Drinking water, urine and toenail samples were obtained to assess arsenic exposure and body burden. Regression analyses indicated significant associations of pinprick scores and vibration thresholds with all arsenic measures. Vibration thresholds were more strongly associated with urinary than water or nail arsenic measures, but odds ratios for decreased pinprick sensitivity were highest for the water arsenic measure. Results of the current study indicate neurosensory effects of arsenic exposure at concentrations well below the 1000 microg/L drinking water level specified by NRC, and suggest that non-carcinogenic end-points, such as vibration thresholds, are useful in the risk assessment of exposure to arsenic in drinking water.",
Arsenic,628490,"Arsenic exposure and age- and sex-specific risk for skin lesions: A population-based case-referent study in Bangladesh Abstract: BACKGROUND: The objective of this population-based case-referent study in Matlab, Bangladesh, was to assess the susceptibility to arsenic-induced skin lesions by age and sex, in a population drinking water from As-contaminated tube wells. METHODS: Identification of As-related skin lesions was carried out in three steps: a) screening of the entire population > 4 years of age (n = 166,934) by trained field teams; b) diagnosis of suspected As-related cases by physicians; and c) confirmation by experts based on physicians' records and photographs. A total of 504 cases with skin lesions were confirmed. We randomly selected 2,201 referents from the Matlab health and demographic surveillance system; 1,955 were eligible, and 1,830 (94%) were available for participation in the study. Individual history of As exposure was based on information obtained during interviews and included all drinking-water sources used since 1970 and concentrations of As (assessed by atomic absorption spectrophotometry) in all the tube wells used. RESULTS: Cases had been exposed to As more than referents (average exposure since 1970: male cases, 200 microg/L; female cases, 211 microg/L; male referents, 143 microg/L; female referents, 155 microg/L). We found a dose-response relationship for both sexes (p < 0.001) and increased risk with increasing socioeconomic status. Males had a higher risk of obtaining skin lesions than females (odds ratio 10.9 vs. 5.78) in the highest average exposure quintile (p = 0.005). Start of As exposure (cumulative exposure) before 1 year of age was not associated with higher risk of obtaining skin lesions compared to start of As exposure later in life. CONCLUSIONS: The results demonstrate that males are more susceptible than females to develop skin lesions when exposed to As in water from tube wells.",
Arsenic,2215710,"Electro-chemical arsenic remediation: Field trials in West Bengal Abstract: Millions of people in rural South Asia are exposed to high levels of arsenic through groundwater used for drinking. Many deployed arsenic remediation technologies quickly fail because they are not maintained, repaired, accepted, or affordable. It is therefore imperative that arsenic remediation technologies be evaluated for their ability to perform within a sustainable and scalable business model that addresses these challenges. We present field trial results of a 600L Electro-Chemical Arsenic Remediation (ECAR) reactor operating over 3.5months in West Bengal. These results are evaluated through the lens of a community scale micro-utility business model as a potential sustainable and scalable safe water solution for rural communities in South Asia. We demonstrate ECAR's ability to consistently reduce arsenic concentrations of ~266?g/L to <5?g/L in real groundwater, simultaneously meeting the international standards for iron and aluminum in drinking water. ECAR operating costs (amortized capital plus consumables) are estimated as $0.83-$1.04/m(3) under realistic conditions. We discuss the implications of these results against the constraints of a sustainable and scalable business model to argue that ECAR is a promising technology to help provide a clean water solution in arsenic-affected areas of South Asia.",
Arsenic,1579333,"Simultaneous preconcentration of toxic elements in artificial saliva extract of smokeless tobacco product, mainpuri by cloud point extraction method Abstract: It has been extensively investigated that smokeless tobacco chewing can lead mainly to inflammation of oral cavity. In present study, the total and artificial saliva extracted toxic elements, arsenic, cadmium, nickel and lead were estimated in smokeless tobacco product, mainpuri. Cloud point extraction has been used for the preconcentration of arsenic, cadmium, nickel and lead in artificial saliva extract, using complexing reagent, ammonium pyrrolidinedithiocarbamate. Total and extractable toxic elements were measured by electrothermal atomic absorption spectrometry. The chemical variables of cloud point extraction were optimized. The validity of methodology was tested by simultaneously analyzing certified reference material (Virginia tobacco leaves) and spike recovery test. The artificial saliva extractable levels of arsenic, cadmium, nickel and lead ranged from 15-22, 45-70, 35-58, and 18-32%, respectively, of total elemental contents in mainpuri samples. It was estimated that intake of 10g of different brands of mainpuri contributing the 5.88, 55.0, 45.0 and 40.3% of the provisional maximum tolerable daily intake for arsenic, cadmium, nickel and lead, respectively for adults of ~60kg.",
Arsenic,2279079,"Biological toxicity of groundwater in a seashore area: Causal analysis and its spatial pollutant pattern Abstract: To ensure the safety of groundwater usage in a seashore area where seawater incursion and unexpected leakage are taking place, this paper utilizes the Microtox test to quantify the biological toxicity of groundwater and proposes an integrated data analysis procedure based on hierarchical cluster analysis (HCA) and principal component analysis (PCA) for determining the key environmental factors that may result in the biological toxicity, together with the spatial risk pattern associated with groundwater usage. For these reasons, this study selects the coastal area of Taichung city in Central Taiwan as an example and implements a monitoring program with 40 samples. The results indicate that the concentration of total arsenic in the coastal areas is about 0.23-270.4?gL(-1), which is obviously higher than the interior of Taichung city. Moreover, the seawater incursion and organic pollution in the study area may be the key factors resulting in the incubation of toxic substances. The results also indicate that As(3+) is the main contributor to biological toxicity compared to other disinfection by-products. With the help of the visualized spatial pollutants pattern of groundwater, an advanced water quality control plan can be made.",
Arsenic,1256742,"Influence of Polluted SY River on Child Growth and Sex Hormones Abstract: <strong>OBJECTIVE: </strong>To investigate the influence of the polluted SY River on children's growth and sex hormones, and provide scientific data for assessment of the polluted status of the SY River.<br /><br /><strong>METHODS: </strong>The study areas were selected randomly from the SY River Basin. Lead (Pb), mercury (Hg), arsenic (As), phthalates (DEP, DBP, DMP, DEHP), and bisphenol A (BPA) were measured both in the river water and in the drinking water. School children were selected by cluster sampling (n=154). Physical development indexes (height, weight, bust-circumference, and skinfold thickness) and sex hormones [testosterone (T) and estradiol (E2)] were measured for all the children.<br /><br /><strong>RESULTS: </strong>The contents of Pb and Hg exceeded Class V standards of surface water quality in each section of the river and other indicators exceeded Class III. Compared to the control area, the concentrations of Pb, Hg, As, BPA, DEP, and DBP in the drinking water were significantly higher than in the polluted area (P<0.05). Children from the control area had significantly lower E2 and T than children from the polluted area (P<0.05). Among anthropometric results, only skinfold thickness had statistically significant difference between the two groups (P<0.05), while the other indexes showed no significant differences between the two groups (P>0.05).<br /><br /><strong>CONCLUSION: </strong>The drinking water has been polluted by the SY River and affected serum sex hormone levels of children living in the polluted area.",
Arsenic,1025103,"Responses of 6500 households to arsenic mitigation in Araihazar, Bangladesh Abstract: This study documents the response of 6500 rural households in a 25 km(2) area of Bangladesh to interventions intended to reduce their exposure to arsenic contained in well water. The interventions included public education, posting test results for arsenic on the wells, and installing 50 community wells. Sixty-five percent of respondents from the subset of 3410 unsafe wells changed their source of drinking water, often to new and untested wells. Only 15% of respondents from the subset of safe wells changed their source, indicating that health concerns motivated the changes. The geo-referenced data indicate that distance to the nearest safe well also influenced household responses.",
Arsenic,1378703,"Pancreatic Oxidative Damage And Endocrine Function In Rats Subchronically Exposed To Arsenite Abstract: Chronic exposure to inorganic arsenic (iAs) contributes to oxidative stress in several organs and systems through production of reactive oxygen species. Since the pancreas is a susceptible organ to the oxidative stress and target of the toxic action of iAs exposure, our study evaluated the presence of oxidative stress and endocrine function of pancreas in rats subchronically exposed to iAs. The oral glucose tolerance test (OGTT) was performed in male Wistar rats after 60 days of treatment with sodium arsenite at 1.7mgAs3+/kg/12h. The effect of subchronic iAs administration on blood glucose, serum insulin, lipid peroxidation (LPO), levels of glutathione (GSH) and As species in pancreas were evaluated after 90 days of iAs treatment in other group of male Wistar rats exposed with sodium arsenite at 1.7mgAs3+/kg/12h. The OGTT shown an impaired glucose tolerance. Hyperinsulinemia (2.7?0.9 vs 1.4?0.6 ng/ml of control group) and hyperglycemia (9.3? 0.7 vs 7.1 ?0.8 mmol/l) was observed at the end of iAs treatment. On the other hand the pancreatic LPO and glutathione levels increased significantly in iAs exposed rats. Dimethylated arsenic (DMA) was the main specie present in the pancreas. The results of this study suggest that subchronic iAs exposure causes oxidative damage and pancreatic beta cell dysfunction related to insulin resistance and hyperglycemia. These results may be related with the presence of pre-diabetes status.",
Arsenic,1070480,"Health assessment of free-ranging and captive Matschie's tree kangaroos (Dendrolagus matschiei) in Papua New Guinea Abstract: Medical evaluations were performed on free-ranging and captive Matschie's tree kangaroos (Dendrolagus matschiei) in Papua New Guinea. The health assessment included physical examination, morphometrics, cloacal swab; and blood, hair, and feces collection. Radio-collars were placed on free-ranging tree kangaroos to determine home range and forest habitat use. The free-ranging tree kangaroos were lightly anesthetized with tiletamine/zolazepam for the data collection. A total of nine free-ranging and seven captive tree kangaroos were evaluated; medical samples were collected from six and five animals, respectively. Results of physical examination, anesthetic monitoring, serum vitamin, mineral, trace nutrient, and electrolytes, whole blood heavy metal analysis, mycobacterial screening, and fecal examinations are presented. Free-ranging tree kangaroos had significantly lower values for beta carotene, copper, selenium, molybdenum, lead, and arsenic and significantly higher values for vitamin E than captive individuals. Cloacal swabs were all negative for Mycobacterium avium via polymerase chain reaction. Some free-ranging and captive individuals had positive coprologic exams revealing Eimeria spp. oocysts and strongyle spp. type ova. These are the first medical and anesthetic data published on Matschie's tree kangaroos from Papua New Guinea.",
Arsenic,2337081,"A new and sensitive method for the determination of trace arsenic using differential pulse polarography Abstract: A new and simple differential pulse polarographic method has been developed for the trace determination of arsenic. When selenite was added into solutions of some ions such as copper, lead, cadmium, zinc, and chromium, their differential pulse polarographic peak decreased. A new reduction peak appeared at a more positive potential than the ion present and it was always higher than the corresponding reduction peak of the ion. Thus, we made use of this interference for the trace determination of As(III). By the addition of selenite onto As(III), a new As-Se intermetallic compound peak was formed at about -0.35 V (pH at about 1.0-2.0). The trace arsenic concentration could be determined simply from this peak by the addition of standard arsenic into a polarographic cell. In the presence of large amounts of selenite, 2 x 10(-7) mol/L As(III) could be determined from this peak precisely. With the newly established method, the limit of detection was 1 x 10(-8) mol/L (S/N = 3). Among the most common cations and anions, only Cd-Se and Pb-Se intermetallic compound peaks had an overlap with the As-Se peak. This interference could be eliminated simply by the addition of EDTA. This method was applied successfully for the determination of arsenic in a digested beer sample.",
Arsenic,82862,"Environmental arsenic exposure of children around a former copper smelter site Abstract: Arsenic residues in the communities surrounding former smelters remain a public health concern, especially for infants and children. To evaluate environmental exposure among these children, a population-based cross-sectional study was conducted in the vicinity of a former copper smelter in Anaconda, Montana. A total of 414 children less than 72 months old were recruited. First morning voided urine samples and environmental samples were collected for arsenic measurements. The geometric mean of speciated urinary arsenic was 8.6 microg/liter (GSD = 1.7, N = 289). Average arsenic levels of different types of soil ranged from 121 to 236 microg/g and were significantly related to proximity and wind direction to the smelter site. The same significant relationship was observed for interior dust arsenic. Speciated urinary arsenic was found to be significantly related to soil arsenic in bare areas in residential yards (P < 0.0005). In general, elevated excretion of arsenic was demonstrable and warranted parents' attention to reduce exposure of their children to environmental arsenic.",
Arsenic,1346473,"Impact of dimethyl sulfoxide and examples of combined genotoxicity in the SOS chromotest Abstract: The bacterial SOS chromotest with Escherichia coli PQ37 was used for the assessment of genotoxicity of combined xenobiotic treatments. The modulation of test compound genotoxicity by dimethyl sulfoxide (DMSO), a common solvent for test compounds, was assessed as well. It was shown that DMSO modulated SOS chromotest genotoxicity of several xenobiotics: in comparison to test compound dissolution in water, the commonly used addition of 3.2% (v/v) DMSO as solvent lead to a significant increase in the genotoxicity of K(2)RhCl(5) and beta-propiolactone (BPL). However, the effects of cisplatin decreased significantly when DMSO was added. Thus, albeit DMSO is not genotoxic in this test itself, it can interfere with SOS chromotest responses. Further experiments were performed in the absence of DMSO. BPL and cisplatin in combination showed an over-additive synergism in SOS genotoxicity as well as K(2)RhCl(5) and cisplatin did. Addition of Pd(NH(3))(4)Cl(2) and NaAsO(2), which are non-genotoxic in the SOS chromotest, did not enhance the K(2)RhCl(5)- or BPL-mediated SOS sfiA induction. Nevertheless, at the highest subcytotoxic dose of NaAsO(2) tested (200 microM), a slight yet significant suppression of BPL-mediated SOS genotoxicity was observed. These results confirm that the SOS chromotest is a useful tool for the rapid evaluation of the combined genotoxicity of compound mixtures. However, the use of DMSO as test solvent has to be taken with caution.",
Arsenic,485541,"Effects of combined administration of captopril and DMSA on arsenite induced oxidative stress and blood and tissue arsenic concentration in rats Abstract: We compared the therapeutic efficacy of captopril and a thiol chelating agent, meso 2,3-dimercaptosuccinic acid (DMSA) either individually or in combination against arsenite induced oxidative stress and mobilization of metal in rats. Animals were exposed to 100 ppm arsenite as sodium arsenite in drinking water for six weeks followed by treatment with DMSA (50 mg/kg, orally), captopril (50 mg/kg, intraperitoneally) either alone or in combination, once daily for 5 consecutive days. Arsenite exposure led to a significant depletion of blood delta-aminolevulinic acid dehydratase (ALAD) activity, glutathione and platelet levels while significantly increased the level of reactive oxygen species (in RBCs). Hepatic reduced glutathione (GSH) level showed a significant decrease while, thiobarbituric acid reactive substances (TBARS) levels increased on arsenite exposure indicating arsenite induced hepatic oxidative stress. Kidney GSH, GSSG, catalase and TBARS remained unchanged on arsenite exposure. Treatment with DMSA was effective in increasing ALAD activity while, captopril was ineffective when given alone. Captopril when co-administered with DMSA also provided no additional beneficial effect on blood ALAD activity but significant brought altered platelet counts back to the normal value. In contrast, administration of captopril alone provided significant beneficial effects on hepatic oxidative stress, and in combination with DMSA provided a more pronounced recovery in the TBARS level compared to the individual effect of DMSA and captopril. Renal biochemical variables remained insensitive to arsenite and any of the treatments. Interestingly, combined administration of captopril with DMSA had a remarkable effect in depleting total arsenic concentration from blood and soft tissues. These results lead us to conclude that captopril administration during chelation treatment had some beneficial effects particularly on the protection of inhibited blood ALAD activity, and depletion of arsenic level. The study supports our earlier conclusion that a co-administration of an antioxidant is more beneficial than monotherapy with the chelating agents, in order to achieve optimal effects of chelation in arsenite toxicity. (c) 2006 Elsevier Inc. All rights reserved.",
Arsenic,1352575,"Glutathione efflux from cultured astrocytes Abstract: The characteristics and kinetics of GSH efflux from the monolayer culture of rat astrocytes were investigated. GSH efflux was dependent on temperature, with a Q10 value of 2.0 between 37 and 25 degrees C. The GSH efflux rate showed a hyperbolic dependency on the intracellular GSH concentration. The data were fitted well to the Michaelis-Menten model, giving the following kinetic parameter values: Km = 127 nmol/mg of protein; Vmax = 0.39 nmol/min/mg of protein. p-Chloromercuribenzenesulfonic acid, a thiol-reactive agent impermeable to the cell membrane, lowered the GSH efflux rate by 25% without affecting the intracellular GSH content. These results suggest that a carrier is involved in the efflux of GSH. The GSH content of cultured astrocytes showed a marked increase when the cells were exposed to insults, such as sodium arsenite, cadmium chloride, and glucose/glucose oxidase that lead to the generation of hydrogen peroxide. The increase in GSH content was attributed to the induction of the cystine transport activity by the agents. Although the intracellular GSH concentration and GSH efflux were increased, the kinetics of GSH efflux were not affected by those agents that imposed the oxidative stress. Because the Km value is very large, it is suggested that astrocytes release GSH depending on their GSH concentration in a wide range.",
Arsenic,2215694,"Relationship between drinking water and toenail arsenic concentrations among a cohort of Nova Scotians Abstract: Consumption of arsenic-contaminated drinking water is associated with increased cancer risk. The relationship between arsenic body burden, such as concentrations in human toenails, and arsenic in drinking water is not fully understood. We evaluated the relationship between arsenic concentrations in drinking water and toenail clippings among a cohort of Nova Scotians. A total of 960 men and women aged 35 to 69 years provided home drinking water and toenail clipping samples. Information on water source and treatment use and covariables was collected through questionnaires. Arsenic concentrations in drinking water and toenail clippings and anthropometric indices were measured. Private drilled water wells had higher arsenic concentrations compared with other dug wells and municipal drinking water sources (P<0.001). Among participants with drinking water arsenic levels ?1??g/l, there was a significant relationship between drinking water and toenail arsenic concentrations (r=0.46, P<0.0001). Given similar levels of arsenic exposure from drinking water, obese individuals had significantly lower concentrations of arsenic in toenails compared with those with a normal weight. Private drilled water wells were an important source of arsenic exposure in the study population. Body weight modifies the relationship between drinking water arsenic exposure and toenail arsenic concentrations.Journal of Exposure Science and Environmental Epidemiology advance online publication, 25 December 2013; doi:10.1038/jes.2013.88.",
Arsenic,614166,"Differential oxidative stress and DNA damage in rat brain regions and blood following chronic arsenic exposure Abstract: Chronic arsenic poisoning caused by contaminated drinking water is a wide spread and worldwide problem particularly in India and Bangladesh. One of the possible mechanisms suggested for arsenic toxicity is the generation of reactive oxygen species (ROS). The present study was planned 1) to evaluate if chronic exposure to arsenic leads to oxidative stress in blood and brain -- parts of male Wistar rats and 2) to evaluate which brain region of the exposed animals was more sensitive to oxidative injury. Male Wistar rats were exposed to arsenic (50 ppm sodium arsenite in drinking water) for 10 months. The brain was dissected into five major parts, pons medulla, corpus striatum, cortex, hippocampus, and cerebellum. A number of biochemical variables indicative of oxidative stress were studied in blood and different brain regions. Single-strand DNA damage using comet assay was also assessed in lymphocytes. We observed a significant increase in blood and brain ROS levels accompanied by the depletion of GSH/GSSG ratio and glucose-6-phosphate dehydrogenase (G6PD) activity in different brain regions of arsenic-exposed rats. Chronic arsenic exposure also caused significant single-strand DNA damage in lymphocytes as depicted by comet with a tail in arsenic-exposed cells compared with the control cells. On the basis of results, we concluded that the cortex region of the brain was more sensitive to oxidative injury compared with the other regions studied. The present study, thus, leads us to suggest that arsenic induces differential oxidative stress in brain regions with cortex followed by hippocampus and causes single-strand DNA damage in lymphocytes. [ABSTRACT FROM AUTHOR] Copyright of Toxicology & Industrial Health is the property of Sage Publications, Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1326982,"Sodium arsenite suppresses human papillomavirus-16 E6 gene and enhances apoptosis in E6-transfected human lymphoblastoid cells Abstract: The p53 tumor suppressor pathway is disrupted by human papillomavirus (HPV) in most cervical cancer cells. The E6 proteins, which could mediate p53 degradation, are related to cellular immortalization, transformation, and tumor formation. In order to study the E6 abrogated p53 function in stress, we transfected HPV-16 E6 gene to TK6 cells in this study. Here we showed that HPV-16 E6 mRNA levels decreased in a dose dependent manner after sodium arsenite (SA) treatment, but not after X-irradiation. P53, p21, and MDM2 were induced in E6-transfected TK6 cells, as well as in parental TK6 cells after arsenite treatment. But the above proteins were only induced in TK6 cells after X-irradiation. It indicated that arsenite, but not X-ray, could suppress the transcription of E6 gene and therefore activate the p53 tumor suppressor pathway in TK6-E6 cells. After arsenite treatment, TK6-E6 cells showed more sub-G1 apoptosis, activated caspase-3/CPP32 fragment, DNA ladder, and less viability than parental TK6 cells, indicating that arsenite enhanced apoptosis in E6-transfected TK6 cells. In contrast, after X-irradiation, TK6-E6 cells showed less sub-G1 apoptosis and higher viability than parental TK6 cells. Thus, it would be another possible strategy to promote arsenite as another potential candidate for the therapeutic purpose in HPV-positive cancer cells.",
Arsenic,1352708,DIRECT AND INDIRECT EFFECTS OF ARSENIC ON THE SURVIVAL AND FECUNDITY OF ESTUARINE ZOOPLANKTON Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM PREDATOR-PREY RELATIONSHIP GRAZING POLLUTANT IMPACT,
Arsenic,1338831,"A modular cell-based biosensor using engineered genetic logic circuits to detect and integrate multiple environmental signals Abstract: Cells perceive a wide variety of cellular and environmental signals, which are often processed combinatorially to generate particular phenotypic responses. Here, we employ both single and mixed cell type populations, pre-programmed with engineered modular cell signalling and sensing circuits, as processing units to detect and integrate multiple environmental signals. Based on an engineered modular genetic AND logic gate, we report the construction of a set of scalable synthetic microbe-based biosensors comprising exchangeable sensory, signal processing and actuation modules. These cellular biosensors were engineered using distinct signalling sensory modules to precisely identify various chemical signals, and combinations thereof, with a quantitative fluorescent output. The genetic logic gate used can function as a biological filter and an amplifier to enhance the sensing selectivity and sensitivity of cell-based biosensors. In particular, an Escherichia coli consortium-based biosensor has been constructed that can detect and integrate three environmental signals (arsenic, mercury and copper ion levels) via either its native two-component signal transduction pathways or synthetic signalling sensors derived from other bacteria in combination with a cell-cell communication module. We demonstrate how a modular cell-based biosensor can be engineered predictably using exchangeable synthetic gene circuit modules to sense and integrate multiple-input signals. This study illustrates some of the key practical design principles required for the future application of these biosensors in broad environmental and healthcare areas.",
Arsenic,1015761,"Levels and speciation of arsenic in the atmosphere in Beijing, China Abstract: Arsenic levels and speciation in the total suspended particles (TSPs) were quantitatively determined by high performance liquid chromatography on-line coupled with hydride generation atomic fluorescence spectrometry in Beijing, China from February 2009 to March 2011. The high TSP levels fluctuated between 0.07 and 0.79mgm(-3), with a mean level of 0.32±0.17mgm(-3). The total arsenic concentrations ranged from 0.03 to 0.31?gm(-3) (mean: 0.13±0.06?gm(-3)) in Beijing's air. The concentrations of As(III) and As(V) ranged from 0.73 to 20ngm(-3) (mean: 4.7±3.6ngm(-3)) and from 14 to 2.5×10(2)ngm(-3) (mean: 67±35ngm(-3)), respectively. As levels and speciation demonstrated relative higher levels in spring and autumn and lower values in summer and winter. As(V) accounted for 81-99% of the extractable species in the TSP samples which showed that As(V) was the major fraction of the extractable As. Organoarsenic species, monomethylarsonate (MMA) and dimethylarsinate (DMA) were not found in all samples. Higher values of enrichment factors demonstrated that arsenic in TSP mainly come from anthropogenic sources. High As and its species levels in air and respiratory exposure (0.30-0.84?gd(-1)) attributed to higher excess cancer risk ((4.2±2.0)×10(-4)) for people in Beijing.",
Arsenic,1028873,"Axial distribution of arsenic in individual human hairs by solid sampling graphite furnace AAS Abstract: In cases of arsenic poisoning, the distribution of arsenic along the length of a hair can be used to distinguish between chronic and acute exposure. Individual 5-mm segments of a hair were analyzed for their arsenic content by solid sampling graphite furnace atomic absorption spectrophotometry with a mixed Pd-Mg(NO3)2 matrix modifier. Results obtained using arsenic calibration solutions and standard additions to uncontaminated hairs are analytically indistinguishable, allowing aqueous standards to be used for hair analysis. The characteristic mass is 24 pg, and the 3 sigma detection limit is approximately 10 pg. Results obtained for hairs from two victims of arsenic poisoning are in good agreement with those obtained using neutron activation analysis.",
Arsenic,627338,"Sister chromatid exchanges in human peripheral blood lymphocytes after ingestion of high doses of arsenicals Abstract: OBJECTIVE: To evaluate the cytogenetic effects following the ingestion of high doses of arsenicals. METHODS: Determination of the mean sister chromatid exchange (SCE) frequency and the population of high-frequency cells (HFC, cells with a high SCE frequency) in the peripheral blood lymphocytes in four patients who ingested 150 mg KAsO2, 1 g, 10 g and 20 g As2O3 respectively. RESULTS: Doses of 10 g and 20 g significantly increased the HFC frequency and produced a shift in the distribution of the cells in accordance with the number of SCEs. The mean frequency of SCEs/cell was affected only after the highest dose (20 g). CONCLUSION: These results strongly suggest that cytogenetic methods are inappropriate for biomonitoring people occupationally exposed to arsenicals.",
Arsenic,1357820,"Concentration and Chemical Status of Arsenic in the Blood of Pregnant Hamsters during Critical Embryogenesis. 2. Acute Exposur Abstract: The concentration, availability, and chemical composition of arsenic (7440382) (As) in the plasma and red cells in hamster dams was investigated. Pregnant Syrian-hamsters were injected intraperitoneally with 64.2 micromoles/kilogram (micromol/kg) of As(74) labeled sodium-arsenate (7778430) at 8:00 AM on the eighth day of gestation. Arsenate (7778394) and its metabolites in plasma and red cells were determined by ion exchange chromatography. Arsenite (1327533) and the methylated As species were separated using a modified Ag5O method. Tightly bound As and low molecular weight metabolites in red cells were separated by lysing the cells, acidifying, removing arsenate on Dowex2 resin, and separating arsenite and methylated species with ethanol. The concentration of As in whole blood rose to 222micromol/kg within approximately 30 minutes postinjection and then declined to a low of 6.01micromol/kg after five hours. A similar trend was observed in plasma where the high during the same period was 358 and low 5.69micromol/kg, respectively. In the red cells the high level of As was 100 and the low 6.45micromol/kg in the indicated study period. All plasma As was found in the ethanol supernatant fractions. Initially 99 percent of plasma As was in the arsenate form and one percent was present as dimethylarsinate (DMA). After five hours arsenate declined to 36, arsenite increased to 15, and DMA rose to 53 percent on the average. The As was also taken up rapidly by the liver, kidney, and placenta. The total concentration in these tissues was similar to that in maternal blood. The authors state that the investigation provides a firmer base for predicting the teratogenic potential of arsenate in mammals.",
Arsenic,1597320,"Outcomes of endovascular aneurysm repair on renal function compared with open repair Abstract: OBJECTIVE: Recent studies have shown that progressive renal dysfunction may develop in patients after endovascular aneurysm repair (EVAR). Data are conflicting about the effect of EVAR on renal function compared with open repair (OR). The purpose of this study was to compare the effects of EVAR, both with transrenal fixation (TRF) and infrarenal fixation (IRF), vs OR on renal function detected with renal perfusion scintigraphy (RPS). METHODS: A prospective study was carried out from January 2003 to December 2007. Exclusion criteria included factors that could influence post-procedural renal function as: preoperative creatinine clearance level &lt;65 mL/min for men and 60 mL/min for women, renal artery stenosis &gt;60%, renal accessory artery planned to be covered by the endograft, single functioning kidney, hemodialysis, and kidney transplant. To evaluate renal function, an RPS was performed preoperatively, at 30 days, at 6 and 12 months, and then yearly. The glomerular filtration rate (GFR) was estimated with the Gates method. RESULTS: During the study period, 403 patients were enrolled; 243 (60%) had OR and 160 (40%) EVAR; among these, 83 (51%) had a TRF and 77 (48%) an IRF; 55 patients were excluded from the study. No statistical differences were observed between groups for demographics and risk factors. Statistically significant differences emerged between OR and EVAR for early postoperative death (4% vs 0%; P = .01). Follow-up ranged from 54 to 126 months (mean, 76 months) for OR and from 54 to 124 months (mean, 74 months) for EVAR (P = NS). Kaplan-Meier analysis survival rate at 9 years was 70% for OR and 58% for EVAR with a risk of secondary procedure of 9% and 34%, respectively (P &lt; .0001). A deterioration of the GFR was observed during the follow-up in both groups with a decrease after 9 years of 11% in the EVAR group and 3% in the OR group respective to baseline (P &lt; .001). A remarkable difference emerged on renal function between EVAR patients who required a secondary procedure compared with the other EVAR patients (P &lt; .005). No significant differences emerged between TFR and IRF for GFR decline during the follow-up period. CONCLUSIONS: After EVAR, there is a continuous decline in renal function with respect to OR, regardless of fixation level and independently of pre-existing renal insufficiency. The risk of GFR impairment after EVAR should be taken into consideration in selecting patients with preoperative renal insufficiency.",
Arsenic,1936073,"Differential arsenic binding in the sediments of two sites in Chile's lower Loa River basin Abstract: Fluvial sediments from two lower Loa River basin sites in northern Chile were compared in order to probe the effects of vegetation and organic matter (OM) on As accumulation in fluvial environments. The two sites were the Sloman dam, which lacks macrophytes and has a low OM content (2.4%) in sediments, and the Quillagua Oasis, which is 23 km downstream from the Sloman site and has a higher OM (6.2%) in sediments and abundant aquatic plant life. The Quillagua site had preferential As enrichment with a co-occurrence pattern that differed from that of the Sloman site, which had a lower As concentration (1528 vs. 262 mg/kg d.w., respectively). At the Quillagua site, As concentration was strongly correlated with Mn and OM (r=0.91 and 0.85, respectively); while at the Sloman site, As concentration in sediments was significantly correlated with Ca and Sr (r=0.63 and 0.54, respectively). Sequential extraction analyses showed that the Sloman site had higher percentage of easily exchangeable As within the surface sediment (12%, 45 mg/kg d.w.) compared with the Quillagua site (3%, 40 mg/kg d.w.). These contrasting results suggest that both vegetation and OM control the immobilization and accumulation of As in the arid Loa River basin.",
Arsenic,2347788,"Adsorption of arsenite from groundwater using titanium dioxide Abstract: Upper tract urothelial cancer (UTUC) is a rare malignant disease with few known environmental risk factors. In particular, arsenic has not been clearly associated to higher UTUC incidence or mortality rates. Antofagasta is a well-known arsenic-exposed region in Northern Chile, with a significant impact of this geologic factor on public health, even two decades after having controlled arsenic concentrations in drinking-water. The aim of the study was to assess UTUC health care needs and mortality rates in this affected region during the last decades, comparing them to those of the rest of the country.",
Arsenic,1936027,"Arsenic immobilization as alunite-type phases: The arsenate substitution in alunite and hydronium alunite Abstract: AsO4-for-SO4 substitution in alunite (KAl3(SO4)2(OH)6) and hydronium alunite ((H3O)Al3(SO4)2(OH)6) has been investigated by hydrothermal precipitation at 200°C. Arsenical alunite presented a good precipitation yield and a significant AsO4 substitution (up to 15% molar). The degree of arsenate substitution depends on the solution composition. It increased as (AsO4/(AsO4+SO4))alunite?0.5 (AsO4/(AsO4+SO4))L. For (AsO4/(AsO4+SO4))L&lt;0.26, arsenical alunite was the unique phase and, above this ratio, mansfieldite (AlAsO4·2H2O) co-precipitated. The a unit cell parameter is practically independent of the AsO4 substitution, but the c unit cell parameter increased consistently with the differences between the AsO1 and SO1 distances in tetrahedral sites of the structure. The maximum stability of arsenical alunite in short-term tests is between pH 5 and 8, with an As-solubilization of 0.01-0.03mg/L in 24h. Long-term tests were performed at some synthesized samples at its natural pH. Arsenical alunite was stabilized at 0.3mg/L released As in 2.5 weeks. These values were similar to those obtained in pure and largely crystalline natural scorodite (0.4mg/L released As), but lower than the obtained for synthetic scorodite (1.3mg/L released As). Thus, arsenical alunite could be effective for arsenic immobilization, especially for effluents or wastes containing large SO4/AsO4 ratio. Hydronium alunite presents a low precipitation yield and a very low arsenate incorporation (up to 1% molar). This may be related by the difficulty of substituting protonated H2O-for-OH(-) groups, due to the location of the H-bridges of the H3O in the structure. These characteristics make hydronium alunite unsuitable for arsenic immobilization.",
Arsenic,1017940,"Association of genotoxic effects of arsenic with haematological malignancy in West Bengal Abstract: Arsenic is a naturally occurring metalloid that has been associated with increased incidence of human cancers in certain highly exposed populations. This present work aimed to study whether arsenic plays any role in the increased incidence of blood cancer among residents of West Bengal, India, which is one of the worst arsenic-affected areas of the world. Our study group included both blood cancer patients and age-, sex-matched healthy controls. We studied the arsenic concentration in the hair and nail samples of our study group. We found significantly higher arsenic concentration in the biological tissues of patients, which also correlated with their greater incidence of chromosomal aberrations. Thus, arsenic may act as a predisposing factor for blood cancer.",
Arsenic,1252634,"Calcium efflux from sarcoplasmic reticulum microsomes due to oxidation and sulfhydryl-binding agents Abstract: Calcium permeability of sarcoplasmic reticulum (SR) microsomes was measured after aging or after exposure to peroxydisulfate or to sulfhydryl-binding agents. Under conditions where the Ca2+-ATPase was active, the maximum net release of Ca2+ was not significantly different between control and oxidized SR. However, when calcium uptake was prevented by EGTA or apyrase, the Ca2+ permeability of oxidized microsomes was 2 to 3 times greater than control of low (10(-9), 10(-7) M) but not high (10(-6) M) levels of external calcium. The observation that vesicles preincubated with 5 mM dithiothreitol loaded up to 3 times as much calcium and had a slightly lower calcium permeability coefficient than control vesicles suggested that sulfhydryl oxidation might modulate calcium flux. This hypothesis was tested by exposing to sulfhydryl-binding agents: silver, arsenite, and p-chloromercuriphenylsulfonic acid. Sulfhydryl-binding agents initiated a rapid release of calcium from microsomes, and release was halted by dithiothreitol. Inhibition of calcium transport could not entirely account for the apparent increase in permeability because the calcium permeability of SR treated with sulfhydryl-binding agents was 5 times greater than that of SR exposed to Ca2+-ATPase inhibitors. These results suggest that oxidation may increase the calcium permeability of SR by allowing calcium loss through a channel that can be gated by sulfhydryl oxidation.",
Arsenic,1508546,"In utero exposure to low dose arsenic via drinking water impairs early life lung mechanics in mice Abstract: <strong>BACKGROUND: </strong>Exposure to arsenic via drinking water is a significant environmental issue affecting millions of people around the world. Exposure to arsenic during foetal development has been shown to impair somatic growth and increase the risk of developing chronic respiratory diseases. The aim of this study was to determine if in utero exposure to low dose arsenic via drinking water is capable of altering lung growth and postnatal lung mechanics.<br /><br /><strong>METHODS: </strong>Pregnant C57BL/6 mice were given drinking water containing 0, 10 (current World Health Organisation (WHO) maximum contaminant level) or 100?g/L arsenic from gestational day 8 to birth. Birth outcomes and somatic growth were monitored. Plethysmography and the forced oscillation technique were used to collect measurements of lung volume, lung mechanics, pressure-volume curves and the volume dependence of lung mechanics in male and female offspring at two, four, six and eight weeks of age.<br /><br /><strong>RESULTS: </strong>In utero exposure to low dose arsenic via drinking water resulted in low birth weight and impaired parenchymal lung mechanics during infancy. Male offspring were more susceptible to the effects of arsenic on growth and lung mechanics than females. All alterations to lung mechanics following in utero arsenic exposure were recovered by adulthood.<br /><br /><strong>CONCLUSIONS: </strong>Exposure to arsenic at the current WHO maximum contaminant level in utero impaired somatic growth and the development of the lungs resulting in alterations to lung mechanics during infancy. Deficits in growth and lung development in early life may contribute to the increased susceptibility of developing chronic respiratory disease in arsenic exposed human populations.",
Arsenic,73121,"Intracellular survival of Staphylococcus aureus due to alteration of cellular activity in arsenic and lead intoxicated mature Swiss albino mice Abstract: The role of heavy metals like arsenic (As) and lead (Pb) as environmental toxicants is established. However, the exact mechanism of their effect on immunocompetent cell activity is not well known. Staphylococcus aureus is a virulent pathogen that has the ability to cause a variety of potentially life-threatening infections. The objective of our study was to demonstrate in an experimental mouse model of bacteremic S. aureus infection, bacterial clearance from blood and spleen in arsenic, lead treated and control group of mice. Bacterial density was measured in blood and spleen after 0, 24, 48 and 72 h post-infection. Our findings show a significant increase in bacterial load in blood (P<0.025 for arsenic and P<0.01 for lead) and delayed bacterial clearance by spleen in both arsenic (P<0.05) and lead (P<0.025) treated groups as compared to control, thus highlighting an immuno-compromised state following heavy metal exposure. To further elucidate immunomodulatory effects of both arsenic and lead, cell function studies were performed on splenic macrophages (M""P"") isolated from lead and arsenic treated as well as control group of mice. Our findings show a decrease in cell adhesion property (P<0.005) of splenic M""P"" 's from 2.9925?0.053 in control to 1.395?0.106 in arsenic and 0.8835?0.0106 in lead treated mice at 60 min. Morphologic alteration of the splenic M""P"" 's showed an increase (As: P<0.05, Pb: P<0.0005) in both arsenic (6.876?0.3287%) and lead (16.55?1.051%) treated mice to control (2.649?1.238%) which may be responsible for the formersÆ reduced functional status. The chemotactic index, a measure of chemotactic migration of the macrophages toward immune serum, was 16.43?1.007 in control cell and was reduced (P<0.0005) to 4.19?0.393 in arsenic and 2.92?0.649 in lead treated mice at 60 min. These altered cell functions could probably explain the intracellular survival of S. aureus but such a causal relationship awaits further detailed examination.",
Arsenic,735026,"Toxicity of inorganic arsenic and its metabolites on haematopoietic progenitors “in vitro”: Comparison between species and sexes Abstract: Inorganic arsenic (iAs) and its metabolites are transferred to the foetus through the placental barrier and this exposure can compromise the normal development of the unborn. For this reason, we assessed the toxicity of sodium arsenite (iAs(III)) and its metabolites dimethylarsinic acid (DMA(V)), monomethylarsonic acid (MMA(V)) and monomethylarsonous acid (MMA(III)) on human haematopoietic cord blood cells and murine bone marrow progenitors in vitro, looking at the effects induced at different concentrations in the two genders. The expression of two enzymes responsible for arsenic biotransformation arsenic methyltranferase (AS3MT) and glutathione S-transferase omega 1 (GSTO1) was evaluated in human cord blood cells. Cord blood and bone marrow cells were exposed in vitro to iAs(III) at a wide range of concentrations: from 0.0001 microM to 10 microM. The methylated arsenic metabolites were tested only on human cord blood cells at concentrations ranging from 0.00064 microM to 50 microM. The results showed that iAs(III) was toxic on male and female colony forming units to about the same extent both in human and in mouse. Surprisingly, very low concentrations of iAs(III) increased the proliferation rate of both human and murine female cells, while male cells showed no significant modulation. MMA(V) and DMA(V) did not exert detectable toxicity on the cord blood cells, while MMA(III) had a marked toxic effect both in male and female human progenitors. AS3MT mRNA expression was not induced in human cord blood cells after iAs(III) exposure. GSTO1 expression decreased after MMA(III) treatment. This study provides evidence that exposure to iAs(III) and MMA(III) at muM concentrations is associated with immunosuppression in vitro.",
Arsenic,1509329,"External sources vs internal processes: What control inorganic As speciation and concentrations in the Penze estuary? Abstract: Over one year study (12 campaigns), particulate arsenic and dissolved inorganic arsenic (total inorganic As, and arsenite As(III)) levels were determined along the whole salinity gradient of the Penze estuary (12 stations) in Brittany (France). Concentrations, in the range 2-26 nM and 3-56 mu g g(-1) for dissolved inorganic and particulate arsenic, respectively, were relatively high in comparison to pristine systems and were attributed to pig and poultry farming activities taking place in the catchment area. Our results show that variations of dissolved inorganic and particulate arsenic up to mid-estuary were significantly linked to fluvial inputs, these latter being controlled by water discharge and precipitations. Arsenite variations over a large salinity range (S&gt;4) were controlled by those of the marine end-member mainly through bacterial processes. Removal of dissolved species within the water column by adsorption on oxide material was found to be minimal while arsenic fluxes from the sediment control arsenate and arsenite levels in the upper part of the estuary. (C) 2011 Elsevier B.V. All rights reserved.",
Arsenic,1337469,"Biogenesis of photosynthetic complexes in the chloroplast of Chlamydomonas reinhardtii requires ARSA1, a homolog of prokaryotic arsenite transporter and eukaryotic TRC40 for guided entry of Tail-anchored proteins Abstract: as1, for antenna size mutant 1, was obtained by insertion mutagenesis of the unicellular green alga Chlamydomonas reinhardtii. This strain has a low chlorophyll content, 8% with respect to the wild type, and displays a general reduction in thylakoid polypeptides. The mutant was found to carry an insertion into a homolog gene of prokaryotic arsenite transporter (ARSA), whose yeast and mammal counterparts were found to be involved in targeting of Tail-anchored (TA) proteins to cytosol-exposed membranes, essential for several cellular functions. Here, we present the characterisation in a photosynthetic organism of an insertion mutant in an ARSA-homolog gene. The ARSA1 protein was found to be localized in the cytosol and yet its absence in as1 leads to a small chloroplast and a strongly decreased chlorophyll content per cell. ARSA1 appears to be required for optimal biogenesis of photosynthetic complexes because of its involvement in accumulation of TOC34, an essential component of the outer chloroplast membrane translocon (TOC) complex, which, in turn, catalyzes the import of nucleus-encoded precursor polypeptides into the chloroplast. Remarkably, the effect of the mutation appears to be restricted to biogenesis of chlorophyll-binding polypeptides and is not compensated by the other ARSA-homolog encoded by C. reinhardtii genome, implying a non redundant function. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.",
Arsenic,1017475,"Assessing the genotoxic potentials of arsenic in tilapia (Oreochromis mossambicus) using alkaline comet assay and micronucleus test Abstract: This experiment was conducted to study the genotoxic potentials of sodium arsenite (NaAsO(2)) in freshwater fish Oreochromis mossambicus by using alkaline comet assay and micronucleus (MN) test. Fish were exposed to three different concentrations (3 ppm, 28 ppm and 56 ppm) of arsenic and gill, liver and blood tissue samples were collected after 48 h, 96 h and 192 h of exposure. Arsenic exposure induced DNA damage in all tissues examined in a concentration dependent manner. A significant (p&lt;0.05) increase in the comet tail DNA (%) of the exposed fish liver, gill, and blood was observed after 48 h and 96 h of exposure, but a decline in DNA damage was recorded in all the tissues at all the three concentrations studied after 192 h of exposure. Liver tissue exhibited significantly (p&lt;0.05) higher DNA damage at all the concentrations examined, followed by gill and blood. Higher liver tail DNA (51.38 ± 0.21%) refers that it is more prone to injury to arsenic toxicity than the gill and blood. In blood samples arsenic induced micronucleus formation in a concentration dependent manner and highest (5.8 ± 0.46%) value was recorded in 56 ppm after 96 h of exposure, whereas, it was decreased after 192 h of exposure at all the three concentrations of NaAsO(2) examined which refers to the DNA repairing ability of fish to arsenic toxicity. The results of this study depict the genotoxic potentials of arsenic to fish which in turns provide insight on advanced study in aquatic toxicology.",
Arsenic,1936025,"Arsenite removal from aqueous solution by a microbial fuel cell-zerovalent iron hybrid process Abstract: Conventional zerovalent iron (ZVI) technology has low arsenic removal efficiency because of the slow ZVI corrosion rate. In this study, microbial fuel cell (MFC)-zerovalent iron (MFC-ZVI) hybrid process has been constructed and used to remove arsenite (As(III)) from aqueous solutions. Our results indicate that the ZVI corrosion directly utilizes the low-voltage electricity generated by MFC in the hybrid process and both the ZVI corrosion rate and arsenic removal efficiency are therefore substantially increased. The resultant water qualities are compliant with the recommended standards of EPA and WHO. Compared to the ZVI process alone, the H2O2 generation rate and output are dramatically improved in MFC-ZVI hybrid process. Strong oxidants derived from H2O2 can rapidly oxidize As(III) into arsenate (As(V)), which helps to improve the As(III) removal efficiency. The distribution analysis of As and Fe indicates that the As/Fe molar ratio of the flocs in solution is much higher in the MFC-ZVI hybrid process. This phenomenon results from the different arsenic species and hydrous ferric oxides species in these two processes. In addition, the electrosorption effect in the MFC-ZVI hybrid process also contributed to the arsenic removal by concentrating As(V) in the vicinity of the iron electrode.",
Arsenic,1252552,CYTOGENETIC EFFECTS IN MICE AFTER CHRONIC EXPOSURE TO ARSENIC FOLLOWED BY A SINGLE DOSE OF ETHYLMETHANE SULFONATE Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM CHROMOSOME MUTATION STATISTICAL ANALYSIS,
Arsenic,132619,"Metabolism and toxicity of arsenic in human urothelial cells expressing rat arsenic (+3 oxidation state)-methyltransferase Abstract: The enzymatic methylation of inorganic As (iAs) is catalyzed by As(+3 oxidation state)-methyltransferase (AS3MT). AS3MT is expressed in rat liver and in human hepatocytes. However, AS3MT is not expressed in UROtsa, human urothelial cells that do not methylate iAs. Thus, UROtsa cells are an ideal null background in which the role of iAs methylation in modulation of toxic and cancer-promoting effects of this metalloid can be examined. A retroviral gene delivery system was used in this study to create a clonal UROtsa cell line (UROtsa/F35) that expresses rat AS3MT. Here, we characterize the metabolism and cytotoxicity of arsenite (iAsIII) and methylated trivalent arsenicals in parental cells and clonal cells expressing AS3MT. In contrast to parental cells, UROtsa/F35 cells effectively methylated iAsIII, yielding methylarsenic (MAs) and dimethylarsenic (DMAs) containing either AsIII or AsV. When exposed to MAsIII, UROtsa/F35 cells produced DMAsIII and DMAsV. MAsIII and DMAsIII were more cytotoxic than iAsIII in UROtsa and UROtsa/F35 cells. The greater cytotoxicity of MAsIII or DMAsIII than of iAsIII was associated with greater cellular uptake and retention of each methylated trivalent arsenical. Notably, UROtsa/F35 cells were more sensitive than parental cells to the cytotoxic effects of iAsIII but were more resistant to cytotoxicity of MAsIII. The increased sensitivity of UROtsa/F35 cells to iAsIII was associated with inhibition of DMAs production and intracellular accumulation of MAs. The resistance of UROtsa/F35 cells to moderate concentrations of MAsIII was linked to its rapid conversion to DMAs and efflux of DMAs. However, concentrations of MAsIII that inhibited DMAs production by UROtsa/F35 cells were equally toxic for parental and clonal cell lines. Thus, the production and accumulation of MAsIII is a key factor contributing to the toxicity of acute iAs exposures in methylating cells.",
Arsenic,1508686,"Nuclear import and export signals control the subcellular localization of Nurr1 protein in response to oxidative stress Abstract: Orphan receptor Nurr1 participates in the acquisition and maintenance of the dopaminergic cell phenotype, modulation of inflammation, and cytoprotection, but little is known about its regulation. In this study, we report that Nurr1 contains a bipartite nuclear localization signal (NLS) within its DNA binding domain and two leucine-rich nuclear export signals (NES) in its ligand binding domain. Together, these signals regulate Nurr1 shuttling in and out of the nucleus. Immunofluorescence and immunoblot analysis revealed that Nurr1 is mostly nuclear. A Nurr1 mutant lacking the NLS failed to enter the nucleus. The Nurr1 NLS sequence, when fused to green fluorescent protein, led to nuclear accumulation of this chimeric protein, indicating that this sequence was sufficient to direct nuclear localization of Nurr1. Furthermore, two NES were characterized in the ligand binding domain, whose deletion caused Nurr1 to accumulate predominantly in the nucleus. The Nurr1 NES was sensitive to CRM1 and could function as an independent export signal when fused to green fluorescent protein. Sodium arsenite, an agent that induces oxidative stress, promoted nuclear export of ectopically expressed Nurr1 in HEK293T cells, and the antioxidant N-acetylcysteine rescued from this effect. Similarly, in dopaminergic MN9D cells, arsenite induced the export of endogenous Nurr1, resulting in the loss of expression of Nurr1-dependent genes. This study illustrates that Nurr1 shuttling between the cytosol and nucleus is controlled by specific nuclear import and export signals and that oxidative stress can unbalance the distribution of Nurr1 to favor its cytosolic accumulation.",
Arsenic,1337642,"Environmental exposure to arsenic, AS3MT polymorphism and prevalence of diabetes in Mexico Abstract: Exposure to arsenic in drinking water is associated with increased prevalence of diabetes. We previously reported an association of diabetes and urinary concentration of dimethylarsinite (DMAs(III)), a toxic product of arsenic methylation by arsenic (+3 oxidation state) methyltransferase (AS3MT). Here we examine associations between AS3MT polymorphism, arsenic metabolism and diabetes. Fasting blood glucose, oral glucose tolerance and self-reported diagnoses were used to identify diabetic individuals. Inorganic arsenic and its metabolites were measured in urine. Genotyping analysis focused on six polymorphic sites of AS3MT. Individuals with M287T and G4965C polymorphisms had higher levels of urinary DMAs(III) and were more frequently diabetic than the respective wild-type carriers, although the excess was not statistically significant. Odds ratios were 11.4 (95% confidence interval (CI) 2.2-58.8) and 8.8 (95% CI 1.6-47.3) for the combined effects of arsenic exposure &gt;75th percentile and 287T and 4965C genotypes, respectively. Carriers of 287T and 4965C may produce more DMAs(III) and be more likely to develop diabetes when exposed to arsenic.Journal of Exposure Science and Environmental Epidemiology advance online publication, 24 October 2012; doi:10.1038/jes.2012.103.",
Arsenic,1379755,"Stimulation of intracellular Ca2+ elevation in neutrophils by thiol-oxidizing phenylarsine oxide Abstract: Phenylarsine oxide (PAO), a trivalent arsenical compound, stimulated [Ca2+]i elevation in rat neutrophils in a Ca2+-containing medium but caused no appreciable response in a Ca2+-free medium. PAO also induced external Mn2+ entry, which was inhibited by N-acetyl-L-cysteine (NAC), but failed to elicit any appreciable Ba2+ and Sr2+ entry. Pretreatment of neutrophils with thiol-reducing agents including dithiothreitol (DTT), NAC, 2,3-dimercapto-1-propanol (DMP), 2,3-dimercaptopropane-1-sulfonic acid (DMPS) and tris-(2-carboxyethyl)phosphine (TCEP), all greatly inhibited PAO-induced [Ca2+]i elevation. Addition of Ni2+ or La3+ followed by PAO stimulation also attenuated the Ca2+ signals in a concentration-dependent manner. PAO had no significant effect on the production of reactive oxygen intermediates (ROI) and nitric oxide (NO) nor did it decrease cellular low molecular weight thiols levels. PAO-induced [Ca2+]i elevation was significantly inhibited by 1-[6-[17beta-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U-73122), the inhibitor of phospholipase C-coupled processes, genistein, a general tyrosine kinase inhibitor, phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, calyculin A, a cortical actin stabilizer, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY 294002), a phosphoinositide 3-kinase inhibitor, 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365), and cis-N-(2-phenylcyclopentyl)azacyclotridec-1-en-2-amine (MDL-12,330A), the blockers of receptor-gated and store-operated Ca2+ channels, whereas there was no appreciable effect exerted by aristolochic acid, a phospholipase A2 inhibitor, 7-nitroindazole and N-(3-aminomethyl)benzylacetamidine (1400W), the blockers of NO synthase, and by suspension in a Na+-deprived medium. In contrast, 2-aminoethoxydiphenyl borane (2-APB), the blocker of IP3 receptor and Ca2+ influx, enhanced the PAO-induced response. PAO had no effect on the plasma membrane Ca2+-ATPase (PMCA) activity in the pharmacological isolated neutrophil preparation and the neutrophil membrane fractions. These results indicate that PAO stimulates [Ca2+]i rise in rat neutrophils mainly through the oxidation of vicinal thiol groups on the cell surface membrane to activation of a non-store operated Ca2+ entry (non-SOCE) without affecting the activity of PMCA and the plasmalemmal Na+/Ca2+ exchanger.",
Arsenic,1348589,"ALPHA-B-CRYSTALLIN IS A SMALL HEAT-SHOCK PROTEIN Abstract: Sequence similarity between alpha B-crystallin and small heat shock proteins (HSPs) has prompted us to investigate whether alpha B-crystallin expression is induced by heat shock. Indeed, accumulation of alpha B-crystallin was detected immunologically in NIH 3T3 cells after incubation at elevated temperatures and after addition of Cd2+ or sodium arsenite to these cells. Two-dimensional gel electrophoresis revealed identity between alpha B-crystallin from eye lenses and from heat-treated fibroblasts. The promoter of the alpha B-crystallin gene was fused to the bacterial chloramphenicol acetyltransferase gene and was shown to confer heat inducibility on this reporter gene in transient transfection assays. A perfect heat shock element within the promoter region is likely to mediate this response. Small HSPs and alpha B-crystallin were shown to share the following two physical properties: (i) they form supramolecular structures with sedimentation values around 17 S and (ii) they are associated with the nucleus at high temperatures and are localized in the cytoplasm under normal conditions. We conclude that alpha B-crystallin has to be considered a member of the class of small HSPs.",
Arsenic,1357534,Trace elements in the hair of workers of a copper mine and of children living in the vicinity Abstract: Eleven trace elements were determined in the hair of Chuquicamata copper mine workers and of children living in camp by means of neutron activation analysis. Comparative studies demonstrated that concentrations of certain elements were greater than those corresponding to the nonexposed populations. Arsenic exceeded the normal limit considered for this element by health organizations.,
Arsenic,2278431,"Knockdown of p66Shc by siRNA injection rescues arsenite-induced developmental retardation in mouse preimplantation embryos Abstract: Two-cell arrest plays a principal role in the elevated levels of embryo loss during the first week of development in mouse. Previously, we have shown that arsenic can apparently induce 2-cell arrest in mouse preimplantation embryo and the expression of oxidative stress adaptor protein p66(Shc) is up-regulated in this process. In the present study, we demonstrated that microinjection of p66(Shc) siRNA into the pronucleus of zygotes resulted in a markedly decrease in both mRNA and protein levels of p66(Shc). The arsenite-induced 2-cell arrests, along with a reduction in the levels of reactive oxygen species (ROS), were significantly inhibited and the number of embryos developing to morula stage concurrently increased upon p66(shc) siRNA microinjection. These findings indicate that knockdown of p66(shc) improves the developmental competence of arsenite-exposed embryos in vitro by increasing the resistance to oxidative stress. In addition, we highlight the utility of single-embryo analysis in preimplantation embryos.",
Arsenic,1021754,"Interdependent genotoxic mechanisms of monomethylarsonous acid: Role of ROS-induced DNA damage and poly(ADP-ribose) polymerase-1 inhibition in the malignant transformation of urothelial cells Abstract: Exposure of human bladder urothelial cells (UROtsa) to 50 nM of the arsenic metabolite, monomethylarsonous acid (MMA(III)), for 12 weeks results in irreversible malignant transformation. The ability of continuous, low-level MMA(III) exposure to cause an increase in genotoxic potential by inhibiting repair processes necessary to maintain genomic stability is unknown. Following genomic insult within cellular systems poly(ADP-ribose) polymerase-1 (PARP-1), a zinc finger protein, is rapidly activated and recruited to sites of DNA strand breaks. When UROtsa cells are continuously exposed to 50 nM MMA(III), PARP-1 activity does not increase despite the increase in MMA(III)-induced DNA single-strand breaks through 12 weeks of exposure. When UROtsa cells are removed from continuous MMA(III) exposure (2 weeks), PARP-1 activity increases coinciding with a subsequent decrease in DNA damage levels. Paradoxically, PARP-1 mRNA expression and protein levels are elevated in the presence of continuous MMA(III) indicating a possible mechanism to compensate for the inhibition of PARP-1 activity in the presence of MMA(III). The zinc finger domains of PARP-1 contain vicinal sulfhydryl groups which may act as a potential site for MMA(III) to bind, displace zinc ion, and render PARP-1 inactive. Mass spectrometry analysis demonstrates the ability of MMA(III) to bind a synthetic peptide representing the zinc-finger domain of PARP-1, and displace zinc from the peptide in a dose-dependent manner. In the presence of continuous MMA(III) exposure, continuous 4-week zinc supplementation restored PARP-1 activity levels and reduced the genotoxicity associated with MMA(III). Zinc supplementation did not produce an overall increase in PARP-1 protein levels, decrease the levels of MMA(III)-induced reactive oxygen species, or alter Cu-Zn superoxide dismutase levels. Overall, these results present two potential interdependent mechanisms in which MMA(III) may increase the susceptibility of UROtsa cells to genotoxic insult and/or malignant transformation: elevated levels of MMA(III)-induced DNA damage through the production of reactive oxygen species, and the direct MMA(III)-induced inhibition of PARP-1.",
Arsenic,1347214,"Current aspects on the genotoxicity of arsenite and its methylated metabolites: Oxidative stress and interactions with the cellular response to DNA damage Abstract: Increased cancer incidences associated with arsenic exposure have long been recognized Significant levels of arsenic exist at a variety of workplaces including copper, zinc and lead smelters or glass manufacturing, as well as during the production and use of pesticides and herbicides (IARC 1980). Although the commercial use of arsenicals has been largely reduced over the last decades, there is, nevertheless, persistent concern about high levels of arsenic in drinking water in some regions of Argentina, Canada, India, Japan, Taiwan, and Thailand due to natural sources (National Research Council 2001). While exposure to arsenic compounds by inhalation increases the risk of lung cancer (IARC 1980), oral ingestion of arsenic has been associated with increased incidence of skin, lung, kidney, bladder, and liver tumours (Chiou et al. 1995; National Research Council 2001). However, the reason for the carcinogenicity of arsenic compounds is not fully understood. Inorganic arsenic compounds are not significantly mutagenic in bacterial test systems or in mammalian cells in culture, but they are clastogenic, causing mainly chromatid type chromosomal aberrations, sister-chromatid exchanges and micronuclei (for recent reviews see Gebel 2001, Basu et al. 2001).",
Arsenic,8474,"Mortality experience of arsenic-exposed workers Abstract: The mortality experience of all pensioners from a copper smelter who were aged 65 or over between 1949 and 1973 has been studied. An index of arsenic exposure was developed for all operations in the plant for 1973. This was applied to all individuals studied so that a comparative measure could be made of each individual's working-life exposure to arsenic. The overall mortality of this cohort was 12.2% higher than for males living in the same area, of the same ages, and in the same time periods. The excess mortality was due chiefly to respiratory cancer where mortality was three times the expected. Because other contaminants were present in the atmosphere, it is not certain that arsenic was entirely responsible for the respiratory cancer observed, yet a close association with arsenic seems highly likely.",
Arsenic,8390,"Induction by inorganic metal salts of sister chromatid exchanges and chromosome aberrations in human and Syrian hamster cell strains Abstract: Sister chromatid exchange (SCE) and chromosome aberration induction were determined for several inorganic metal salts. Arsenic, nickel and beryllium salts at concentrations effective in causing transformation of Syrian hamster cells (HEC) induced SCE and chromosome aberrations of HEC and human lymphocytes; sodium tungstate, a nontransforming chemical, neither induced SCE nor chromosome aberrations. Normal human and hamster cells exhibited equal sensitivity to SCE induction; nontoxic concentrations of sodium arsenite, beryllium sulfate and nickel sulfate caused an increase of 8-10 SCE/cell over control values. Sodium arsenite, a trivalent arsenic, and sodium arsenate, a pentavalent arsenic, produced increases in SCE, but the former was effective at lower concentrations. Both arsenic salts were less efficient in inducing SCE in human whole blood than in purified lymphocyte cultures. Sodium arsenite, sodium arsenate, nickel sulfate and beryllium sulfate also caused damage consisting primarily of chromatid type of aberrations. In HEC, with doses most effective in SCE induction, all 4 metals produced aberrations in 16-21% of cells. In human lymphocytes, 34 and 30% of the cells had chromosome damage after sodium arsenite and sodium arsenate, respectively; beryllium sulfate or nickel sulfate caused damage inf SCE and chromosomal aberrations by metals reemphasizes the sensitivity of cytological assays and their importance for detecting genetic damage caused by carcinogens.",
Arsenic,1175749,"Influence of prenatal arsenic exposure and newborn sex on global methylation of cord blood DNA Abstract: Background: An emerging body of evidence indicates that early-life arsenic (As) exposure may influence the trajectory of health outcomes later in life. However, the mechanisms underlying these observations are unknown. Objective: The objective of this study was to investigate the influence of prenatal As exposure on global methylation of cord blood DNA in a study of mother/newborn pairs in Matlab, Bangladesh. Design: Maternal and cord blood DNA were available from a convenience sample of 101 mother/newborn pairs. Measures of As exposure included maternal urinary As (uAs), maternal blood As (mbAs) and cord blood As (cbAs). Several measures of global DNA methylation were assessed, including the [3H]-methyl-incorporation assay and three Pyrosequencing assays: Alu, LINE-1 and LUMA. Results: In the total sample, increasing quartiles of maternal uAs were associated with an increase in covariate-adjusted means of newborn global DNA methylation as measured by the [3H]-methyl-incorporation assay (quartile 1 (Q1) and Q2 vs. Q4; p = 0.06 and 0.04, respectively). Sex-specific linear regression analyses, while not reaching significance level of 0.05, indicated that the associations between As exposures and Alu, LINE-1 and LUMA were positive among male newborns (N = 58) but negative among female newborns (N = 43); tests for sex differences were borderline significant for the association of cbAs and mbAs with Alu (p = 0.05 and 0.09, respectively) and for the association between maternal uAs and LINE-1 (p = 0.07). Sex-specific correlations between maternal urinary creatinine and newborn methyl-incorporation, Alu and LINE-1 were also evident (p,0.05). Conclusions: These results suggest that prenatal As exposure is associated with global DNA methylation in cord blood DNA, possibly in a sex-specific manner. Arsenic-induced epigenetic modifications in utero may potentially influence disease outcomes later in life. Additional studies are needed to confirm these findings and to examine the persistence of DNA methylation marks over time.",
Arsenic,1936041,"Application of the positive matrix factorization approach to identify heavy metal sources in sediments. A case study on the Mexican Pacific Coast Abstract: During the last two decades, sediments collected in different sources of water bodies of the Tehuantepec Basin, located in the southeast of the Mexican Pacific Coast, showed that concentrations of heavy metals may pose a risk to the environment and human health. The extractable organic matter, geoaccumulation index, and enrichment factors were quantified for arsenic, cadmium, copper, chromium, nickel, lead, vanadium, zinc, and the fine-grained sediment fraction. The non-parametric SiZer method was applied to assess the statistical significance of the reconstructed metal variation along time. This inference method appears to be particularly natural and well suited to temperature and other environmental reconstructions. In this approach, a collection of smooth of the reconstructed metal concentrations is considered simultaneously, and inferences about the significance of the metal trends can be made with respect to time. Hence, the database represents a consolidated set of available and validated water and sediment data of an urban industrialized area, which is very useful as case study site. The positive matrix factorization approach was used in identification and source apportionment of the anthropogenic heavy metals in the sediments. Regionally, metals and organic matter are depleted relative to crustal abundance in a range of 45-55 %, while there is an inorganic enrichment from lithogenous/anthropogenic sources of around 40 %. Only extractable organic matter, Pb, As, and Cd can be related with non-crustal sources, suggesting that additional input cannot be explained by local runoff or erosion processes.",
Arsenic,1614972,"Arsenic in groundwater and its influence on exposure risks through traditionally cooked rice in Prey Vêng Province, Cambodia Abstract: Arsenic (As) contamination of communal tubewells in Prey Vêng, Cambodia, has been observed since 2000. Many of these wells exceed the WHO As in drinking water standard of 10?g/L by a factor of 100. The aim of this study was to assess how cooking water source impacts dietary As intake in a rural community in Prey Vêng. This aim was fulfilled by (1) using geostatistical analysis techniques to examine the extent of As contaminated groundwater in Prey Vêng and identify a suitable study site, (2) conducting an on-site study in two villages to measure As content in cooked rice prepared with water collected from tubewells and locally harvested rainwater, and (3) determining the dietary intake of As from consuming this rice. Geostatistical analysis indicated that high risk tubewells (&gt;50?g As/L) are concentrated along the Mekong River's east bank. Participants using high risk tubewells are consuming up to 24 times more inorganic As daily than recommended by the previous FAO/WHO provisional tolerable daily intake value (2.1?g/kgBW/day). However, As content in rice cooked in rainwater was significantly reduced, therefore, it is considered to be a safer and more sustainable option for this region.",
Arsenic,2279305,"Investigation of sonochemical activities at a frequency of 334kHz: The effect of geometric parameters of sonoreactor Abstract: In this study, the effect of the dimensions of the bottom plate and liquid height was investigated for high-frequency sonoreactors under a vertically irradiated system. The dimensions of the bottom plate did not significantly influence sonochemical activity considering power density. However, as the bottom plate was increased in size, the hydroxyl radical generation rate decreased because of a decrease in power density. It is therefore recommended that sonoreactors with bottom-plate dimensions close to those of the ultrasonic transducer module be used. Liquid height had a significant effect on sonochemical activity, but the trend of the activity considering power density changed as the initial pollutant concentration changed. In the case of low initial concentration of As(III) (1 mg/L), the maximum cavitation yield for As(III) oxidation was observed at liquid heights of 150 mm.",
Arsenic,656923,"Development of a mechanistically-based genetically engineered PC12 cell system to detect p53-mediated cytotoxicity Abstract: The human wild type p53 gene, key for apoptosis, was introduced into the pheochromocytoma (PCI 2) cell line, to create a mechanistically-based in vitro test model for the detection of p53-mediated toxicity. Expression of the wt p53 gene was regulated by a system, which allowed or blocked expression p53 by absence or presence of tetracycline in the culture media. Western blot analyses confirmed an inducible and tetracycline-dependent expression of the wt p53 protein. Functionality of the p53 protein was verified by camptothecin treatment, known to induce p53-dependent apoptosis. Results showed that p53-expressing cells were significantly more sensitive to camptothecin induced cytotoxicity compared to non-expressing cells, and presented a significantly higher incidence of apoptosis. A screening study on 31 metal compounds, showed that the classified human carcinogens (NaASO(2), CdSO4 center dot 8H(2)O, Na2CrO4 center dot 4H(2)O, MnCl2, (NH4)(2)PtCl6) significantly increased cytotoxicity in p53-expressing cells compared to non-expressing cells, suggesting that their cytotoxicity was p53-mediated. Finally, acute and subchronic treatment with methyl mercury showed no significant differences in cytotoxicity and the percentage of apoptosis or necrosis between p53-expressing and non-expressing differentiated cells, suggesting that methyl mercury cytotoxicity was p53-independent. (C) 2006 Elsevier Ltd. All rights reserved.",
Arsenic,1519060,"Selenium mediated arsenic toxicity modifies cytotoxicity, reactive oxygen species and phosphorylated proteins Abstract: The effect of selenium on modulating arsenic cytotoxicity is well known in mammals, but not well understood. Cell cytotoxicity and reactive oxygen species (ROS) changes were performed in combinations of As(iii) and selenomethionine (SeMet) toxic mixes on, HEK293, human kidney cells. Cell growth is readily restored from 20% to 60% when switching from 30 ?M As(iii) as toxin to a mix of 30 ?M As(iii) and 100 ?M SeMet. As(iii) alone triggers ROS formation, primarily hydrogen peroxide, in a concentration dependent manner as observed through changes in the fluorescence from 2',7'-dichlorofluorescein diacetate. Importantly, SeMet induces lower ROS levels at the same concentrations used to modulate As(iii) cytotoxicity (IC50). Elevated ROS is important to As(iii) cytotoxicity and minimizing it is essential to the SeMet modulating function. Changes in cell signaling, through analysis of signaling changes via differential protein phosphorylation to uncover molecular level changes occurring in HEK293 human kidney cells as SeMet modulates the As(iii) cytotoxicity. To discover changes in the phosphoproteome, cells were incubated under three conditions: 30 ?M As(iii), 100 ?M SeMet, and 30 ?M As(iii) + 100 ?M SeMet. After total protein isolation the three samples were separated into fractions using size exclusion chromatography by detecting (31)P(+). Each sample was analyzed for the phosphorylated peptides by enzymatic digestion, selective enrichment of phosphorylated peptides via TiO2, followed by nanoLC-ESIMS. Phosphorylated proteins unique to the As(iii)-SeMet mixture were then identified. The molecular level changes to the cells show uniquely that the As(iii)-SeMet mixture details proteins involved in ROS detoxification, cell cycle arrest, and protein/DNA damage. This study shows that SeMet not only lowers the total amount of ROS in a cell but also confers upon HEK293 cells the ability to detoxify. Thus, SeMet is not only a potent antioxidant in this system, but induces molecular changes that confer survival.",
Arsenic,626986,"Diabetogenic effects and pancreatic oxidative damage in rats subchronically exposed to arsenite Abstract: Recent epidemiologic studies have associated chronic inorganic arsenic (iAs) exposure with an increase in the prevalence of diabetes mellitus. Currently, the diabetogenic mechanism caused by iAs exposure is unclear. However, it is recognized that iAs contributes to oxidative stress in several organs and systems through generation of reactive oxygen species (ROS). ROS can function as signaling molecules to activate a number of cellular stress-sensitive pathways linked to insulin resistance and decreased insulin secretion. MaleWistar rats were administered sodium arsenite at 1.7 mg/kg (12 h), or water (controls) orally for 90 days. At the end of the 90 days of iAs exposure hyperglycemia, hyperinsulinemia and low insulin sensitivity, evaluated by the homeostasis model assessment of insulin resistance,was observed. Arsenicals in pancreas of rats exposed to iAs were significantly higher than the control group, being dimethyl and trimethyl metabolites the predominant arsenic species. The activity of pancreatic thioredoxin reductase was lower than the control group. Also, the levels of total glutathione and lipoperoxidation in pancreas increased significantly relative to the control group indicating the presence of stress and oxidative damage, respectively. These results represent an attempt to establish an animal model for in vivo studies of diabetogenic effects of chronic arsenic exposure.",1
Arsenic,628436,"Enhanced expression of metallothionein isoform 3 protein in tumor heterotransplants derived from As+3- and Cd+2-transformed human urothelial cells Abstract: This laboratory has proposed that the third isoform of the metallothionein gene family (MT-3) might be a biomarker for the development of human bladder cancer. Immunohistochemical staining of MT-3 on archival diagnostic specimens showed that only 2 of 63 (3.17%) benign bladder specimens had even weak reactivity for the MT-3 protein. In contrast, 103 of 107 (96.26%) high-grade urothelial cancers and 17 of 17 (100%) specimens of carcinoma in situ stained positive for the MT-3 protein. For low-grade bladder cancer it was shown that 30 of 48 specimens (62.5%) expressed the MT-3 protein. Using a cell culture model (UROtsa), it was demonstrated that expression of the MT-3 protein was not required for malignant transformation of urothelial cells by either Cd+2 or As+3. In contrast, it was shown that the cells transformed by Cd+2 and As+3 that did not express the MT-3 gene in cell culture, gained expression of MT-3 when grown as heterotransplants in nude mice. The gain in MT-3 expression when cells were grown as heterotransplants was also shown to occur for the MCF-7, T-47D, Hs 578t, MDA-MB-231 breast cancer, and the PC-3 prostate cancer cell lines. An analysis of MT-3 mRNA and protein expression suggested that a posttranscriptional mechanism was responsible for accumulation of the MT-3 protein. The results provide strong evidence that MT-3 could be a biomarker for the development of high-grade bladder cancer and that the expression of the MT-3 gene is not involved in the in vitro malignant transformation of UROtsa cells by Cd+2 and As+3.",
Arsenic,1026348,"Effects of long-term exposure of the red swamp crawfish Procambarus clarkii to a mixture of two herbicides, 2,4-dichlorophenoxyacetic acid and monosodium methanearsonate, and associated human health risks Abstract: 2,4-dichlorophenoxyacetic acid and monosodium methanearsonate are often sold in commercial mixtures. Bioconcentration studies have been performed for each of these herbicides individually, but little information exists concerning long-term exposure to a mixture of these herbicides. The following study examined the uptake of arsenic in crawfish after long-term exposure to this mixture, and the health risks associated with consumption of these crawfish. Bioconcentration and depuration experiments using a 50:50 by concentration mixture of the two herbicides, with and without surfactant, were performed to quantify how much arsenic is concentrated in the edible tissue of the crawfish. Of the three tissues (muscle, gill, and hepatopancreas) sampled hepatopancreas bioconcentrated the highest amount of arsenic. Surfactant significantly reduced this uptake but did not affect bioconcentration of arsenic into other tissues. Surfactant had no effect on depuration of arsenic from any of the tissues. Cooking lowered hepatopancreatic arsenic content, possibly as a result of structural changes in the hepatopancreas. Assessment of the human health risk associated with consuming these crawfish showed an exposure dose at the high end of consumption that was approximately twice the reference dose for arsenic. Cancer risks were averaged at approximately 7 extra tumors in a population of 10,000 and 6 extra tumors in a population of 10,000 resulting from a lifetime consumption of crawfish exposed to the herbicide mixture without and with surfactant, respectively.",
Arsenic,734856,"Plasma folate level, urinary arsenic methylation profiles, and urothelial carcinoma susceptibility Abstract: To elucidate the influence of folate concentration on the association between urinary arsenic profiles and urothelial carcinoma (UC) risks in subjects without evident arsenic exposure, 177 UC cases and 488 controls were recruited between September 2002 and May 2004. Urinary arsenic species including inorganic arsenic, monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) were determined by employing a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry procedure. After adjustment for suspected risk factors of UC, the higher indicators of urinary total arsenic levels, percentage of inorganic arsenic, percentage of MMA(V), and primary methylation index were associated with increased risk of UC. On the other hand, the higher plasma folate levels, urinary percentage of DMA(V) and secondary methylation index were associated with decreased risk of UC. A dose-response relationship was shown between plasma folate levels or methylation indices of arsenic species and UC risk in the respective quartile strata. The plasma folate was found to interact with urinary arsenic profiles in affecting the UC risk. The results of this study may identify the susceptible subpopulations and provide insight into the carcinogenic mechanisms of arsenic even at low arsenic exposure.",
Arsenic,1597425,Biosorption of Heavy Metals in Leachate Derived from Gold Mine Tailings Using Aspergillus fumigatus Abstract: ,
Arsenic,65321,"Alterations in urethan-induced adenoma formation in mice exposed to selenium and arsenic Abstract: Female Swiss were exposed to sodium selenite (3 micrograms/ml selenium content) and sodium arsenate (80 micrograms/ml arsenic content) in the drinking water individually or in combination on alternate days for 15 weeks. Comparable water consumption was observed in all individual or combined metal-exposure groups. After 3 weeks of metal exposure, the mice were administered urethan (1.5 mg/g) intraperitoneally. Pulmonary adenoma formation was evaluated 12 weeks later. Arsenic exposure reduced the tumor incidence (P = 0.0046) and tumor size (P less than 0.0001). Selenium exposure did not alter the tumor incidence but caused a reduction in tumor size (P = 0.022). No selenium-arsenic interactions associated with tumor size or number were observed. Urethan-induced sleeping times were unaffected by exposure to selenium (P = 0.832) or arsenic (P = 0.42), although combined metal exposure reduced the duration of urethan-induced sleep (P = 0.029) as compared to the individual metal exposures. This metal-metal interaction, which appeared to enhance the rate of urethan elimination as indicated by the reduced sleeping time, did not influence adenoma formation significantly.",
Arsenic,1339209,"Study of heavy metal poisoning in frequent users of Chinese medicines in Hong Kong and Macau Abstract: This study is a direct assessment of blood heavy metal concentrations of frequent users of Chinese medicines (CM), who had been taking prescribed CM at least 6?days per week for not less than 3?months, to determine whether their intake of CM could cause an increased load of toxic heavy metals in the body. From November 2009 to June 2010, 85 subjects were recruited with informed consent, and their blood samples were collected for measurement of arsenic, cadmium, lead and mercury concentrations. Results showed that blood concentrations of four heavy metals of nearly all 85 subjects were within reference ranges. Only one subject who had consumed plentiful seafood was found to have transiently increased blood arsenic concentration (29% higher than the upper limit of the reference range). However, after refraining from eating seafood for 1?month, his blood arsenic concentration returned to normal. Eighty commonly prescribed CM in both raw medicine and powder concentrate supplied by local distributors were also tested for the four heavy metals. Twelve out of the 80 raw medicines were found to contain one or more of the heavy metals that exceeded the respective maximum permitted content. Cadmium was most frequently found in the contaminated samples. None of the powder concentrates had heavy metal content exceeding their respective maximum permitted level.",
Arsenic,1030600,"Dietary exposure and biomarkers of arsenic in consumers of fish and shellfish from France Abstract: Seafood, especially fish, is considered as a major dietary source of arsenic (As). Seafood consumption is recommended for nutritional properties but contaminant exposure should be considered. The objectives were to assess As intake of frequent French seafood consumers and exposure via biomarkers. Consumptions of 996 high consumers (18 and over) of 4 coastal areas were assessed using a validated food frequency questionnaire. Seafood samples were collected according to a total diet study (TDS) sampling method and analyzed for total As, arsenite (AsIII), arsenate (AsV), arsenobetaïne (AsB), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The average As dietary exposure is 94.7+/-67.5 microg/kg bw/week in females and 77.3+/-54.6 microg/kg bw/week in males (p&lt;0.001) and the inorganic As dietary exposure is respectively 3.34+/-2.06 microg/kg bw/week and 3.04+/-1.86 microg/kg bw/week (p&lt;0.05). Urine samples were collected from 382 of the subjects. The average urinary As concentration is 94.8+/-250 microg/g creatinine for females and 59.7+/-81.8 microg/g for males (p&lt;0.001). Samples having an As concentration above 75 microg/g creatinine (n=101) were analyzed for inorganic As (As(III), As(V), MMA(V) and DMA(V)) which was 24.6+/-27.9 microg/g creatinine for males and 27.1+/-20.6 microg/g for females. Analyses do not show any correlation between dietary exposure and urinary As. These results show that biological results should be interpreted cautiously. Diet recording seems to be the best way to assess dietary As exposure. Seafood is a high source of As exposure but even among high consumers it is not the main source of toxic As. From a public health point of view these results should be interpreted carefully in the absence of international consensus on the health-based guidance value.",
Arsenic,1027842,"Plasma protein C activity is enhanced by arsenic but inhibited by fluorescent humic acid associated with blackfoot disease Abstract: Blackfoot disease is a peripheral vascular disease causally related to the fluorescent humic acid found in the drinking water of endemic areas in Taiwan. We compared the effects of humic acid (HA) purified from the well water of Blackfoot disease endemic areas with the effects of commercial humic acid (Aldrich) as well as trivalent arsenic (As2O3) on protein C activity, which plays an important role in regulation of blood coagulation and fibrinolysis. Humic acid, either purified from drinking water or obtained commercially, dose-dependently inhibited both activated protein C activity and the activation of protein C induced by Protac, a snake venom-derived protein C activator. In contrast to humic acid, arsenic oxide dose-dependently enhanced both activated protein C activity and the Protac-stimulated activation of protein C. In the presence of humic acid the enhancement effect of arsenic oxide was completely abolished, resulting in concentration-dependent inhibition of protein C activity. Therefore, the results of this study indicate that humic acid is a potent protein C inhibitor even in the presence of arsenic, which enhances the protein C activity. Since protein C is a potent anticoagulant and profibrinolytic agent, acquired defects of protein C induced by humic acid might cause a thrombophilic or hypercoagulable state. Whether this is one of the possible mechanisms of humic acid-induced thrombotic disorders in Blackfoot disease needs to be further characterized.",
Arsenic,657852,"GSTM1 and APE1 genotypes affect arsenic-induced oxidative stress: A repeated measures study Abstract: BACKGROUND: Chronic arsenic exposure is associated with an increased risk of skin, bladder and lung cancers. Generation of oxidative stress may contribute to arsenic carcinogenesis. METHODS: To investigate the association between arsenic exposure and oxidative stress, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was evaluated in a cohort of 97 women recruited from an arsenic-endemic region of Bangladesh in 2003. Arsenic exposure was measured in urine, toenails, and drinking water. Drinking water and urine samples were collected on three consecutive days. Susceptibility to oxidative stress was evaluated by genotyping relevant polymorphisms in glutathione-s transferase mu (GSTM1), human 8-oxoguanine glycosylase (hOGG1) and apurinic/apyrimidinic endonuclease (APE1) genes using the Taqman method. Data were analyzed using random effects Tobit regression to account for repeated measures and 8-OHdG values below the detection limit. RESULTS: A consistent negative effect for APE1 was observed across water, toenail and urinary arsenic models. APE1 148 glu/glu + asp/glu genotype was associated with a decrease in logged 8-OHdG of 0.40 (95%CI -0.73, -0.07) compared to APE1 148 asp/asp. An association between total urinary arsenic and 8-OHdG was observed among women with the GSTM1 null genotype but not in women with GSTM1 positive. Among women with GSTM1 null, a comparison of the second, third, and fourth quartiles of total urinary arsenic to the first quartile resulted in a 0.84 increase (95% CI 0.27, 1.42), a 0.98 increase (95% CI 033, 1.66) and a 0.85 increase (95% CI 0.27, 1.44) in logged 8-OHdG, respectively. No effects between 8-OHdG and toenail arsenic or drinking water arsenic were observed. CONCLUSION: These results suggest the APE1 variant genotype decreases repair of 8-OHdG and that arsenic exposure is associated with oxidative stress in women who lack a functional GSTM1 detoxification enzyme.",
Arsenic,711023,"Protective role of zinc in ameliorating arsenic-induced oxidative stress and histological changes in rat liver Abstract: The aim of present work was to gain insight into the role of dietary zinc in ameliorating the adverse effects caused by arsenic on rat liver. Male Wistar rats received arsenic alone in the form of sodium arsenite in drinking water at a dose level of 100 ppm, zinc alone in the form of zinc sulfate in drinking water at a dose level of 227 mg/L, or arsenic + zinc treatments in the combined group for a total duration of 3 months. Arsenic treatment resulted in a significant increase in lipid peroxidase (LPO); however, glutathione (GSH) levels and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT) were found to be significantly decreased following arsenic treatment. Furthermore, arsenic treatment resulted in a significant decrease in hepatic zinc levels. Histological studies showed well-differentiated signs of focal hepatitis, lobular inflammation, prominent hepatocyte degeneration, and severe periportal necrosis. Administration of zinc to arsenic-treated rats significantly decreased the level of LPO but increased the level of GSH compared with arsenic-treated rats. Further, the zinc level and activities of SOD, GPx, GR, and CAT were found to be significantly increased following zinc treatment. The administration of zinc to arsenic-treated rats caused signs of improvement in liver histoarchitecture, but a few focal areas of degeneration and necrosis were still occasionally seen. In conclusion, the results of this study suggest that zinc can be beneficial against arsenic-induced hepatotoxicity in rats.",
Arsenic,1508558,"The Accumulation and Distribution of Metals in Water, Sediment, Aquatic Macrophytes and Fishes of the Gruža Reservoir, Serbia Abstract: The concentrations of iron, lead, cadmium, copper, manganese, mercury and arsenic were measured in water, sediment, five macrophytes (Typha angustifolia, Iris pseudacorus, Polygonum amphybium, Myriophyllum spicatum and Lemna gibba) and five fish species (Sander lucioperca, Abramis brama, Carassius gibelio, Silurus glanis and Arystichtys nobilis) in the Gruža Reservoir, used for water supply and recreational fishing. The concentrations of all examined elements were higher in sediment than in water. The values of the ratio between element concentrations in the sediment and those in the water were the highest for Fe and As. Among the five plant species, the highest concentrations of Pb and Mn were observed in T. angustifolia, while the highest concentrations of Fe, Cu and Hg were in L. gibba. I. pseudacorus and P. amphybium had the highest concentrations of Cd and As, respectively. Among the fish species, C. gibelio showed the highest tendency of element accumulation (Fe, Cd, Cu), followed by S. lucioperca (Pb, Hg), A. brama (Mn) and A. nobilis (As). The average concentrations of elements in fish muscle, except for As in A. nobilis (2.635 ± 0.241 mg kg(-1) ww), were below the limits that are considered safe for human consumption in accordance with the European Commission Regulation and Official Gazette of Serbia.",
Arsenic,1348012,CHEMISTRY OF THE PHENOXATHIINS AND ISOSTERICALLY RELATED HETEROCYCLES .20. ARSENIC CONTAINING HETEROCYCLES .2. CONFIRMATION OF THE STRUCTURE OF BENZO[A]-9-CHLOROPHENARSAZINE 12-CHLORIDE BY C-13-NMR SPECTROSCOPY AND SPIN-LATTICE RELAXATION-TIME STUDIES - POSSIBLE EVIDENCE FOR THE CONTRIBUTION OF AN AS-75-C-13 MECHANISM TO THE RELAXATION OF THE ARSENIC BEARING QUATERNARY CARBONS IN THE PHENARSAZINE RING-SYSTEMIM Abstract: ,
Arsenic,154852,"Tissue distribution and urinary excretion of dimethylated arsenic and its metabolites in dimethylarsinic acid- or arsenate-treated rats Abstract: Adult female Fisher 344 rats received drinking water containing 0, 4, 40, 100, or 200 parts per million of dimethylarsinic acid or 100 parts per million of arsenate for 14 days. Urine was collected during the last 24 h of exposure. Tissues were then taken for analysis of dimethylated and trimethylated arsenicals; urines were analyzed for these arsenicals and their thiolated derivatives. In dimethylarsinic acid-treated rats, highest concentrations of dimethylated arsenic were found in blood. In lung, liver, and kidney, concentrations of dimethylated arsenic exceeded those of trimethylated species; in urinary bladder and urine, trimethylated arsenic predominated. Dimethylthioarsinic acid and trimethylarsine sulfide were present in urine of dimethylarsinic acid-treated rats. Concentrations of dimethylated arsenicals were similar in most tissues of dimethylarsinic acid- and arsenate-treated rats, including urinary bladder which is the target for dimethylarsinic acid-induced carcinogenesis in the rat. Mean concentration of dimethylated arsenic was significantly higher (P < 0.05) in urine of dimethylarsinic acid-treated rats than in arsenate-treated rats, suggesting a difference between treatment groups in the flux of dimethylated arsenic through urinary bladder. Concentrations of trimethylated arsenic concentrations were consistently higher in dimethylarsinic acid-treated rats than in arsenate-treated rats; these differences were significant (P < 0.05) in liver, urinary bladder, and urine. Concentrations of dimethylthioarsinic acid and trimethylarsine sulfide were higher in urine from dimethylarsinic acid-treated rats than from arsenate-treated rats. Dimethylarsinic acid is extensively metabolized in the rat, yielding significant concentrations of trimethylated species and of thiolated derivatives. One or more of these metabolites could be the species causing alterations of cellular function that lead to tumors in the urinary bladder.",
Arsenic,2088365,"Sulfur redox chemistry governs diurnal antimony and arsenic cycles at Champagne Pool, Waiotapu, New Zealand Abstract: ",
Arsenic,388058,"Decreased arginine methylation and myelin alterations in arsenic exposed rats Abstract: Methylation has an important role in the synthesis of myelin basic protein (MBP), an essential component that confers compactness to myelin, and the correct synthesis and assembling of myelin are fundamental in the development of the central nervous system. Since arsenic metabolism requires a high consumption of S-adenosylmethionine, the main donor of methyl groups in the organism, it has been proposed that arsenic exposure can lead to a demethylation status in the organism comprising DNA and protein hypomethylation. This study documents myelin alterations in brain and changes in levels of methylated arginines in brain and serum of adult female Wistar rats exposed to arsenic (3 and 36 ppm, drinking water) from gestation throughout lactation, development and until 1, 2, 3 and 4 months of age. Morphological characteristics were analyzed by means of light microscopy and methylated arginines were analyzed through HPLC. Arsenic intake resulted in myelin damage reflected as empty spaces in fiber tracts of the exposed animals. The low exposure group (approximately 0.4 mg/kg/day) did not present myelin damage during the first 2 months, only moderate alterations in the third and fourth months. By contrast, animals exposed to 36 ppm (approximately 4 mg/kg/day) showed moderate to severe damage to nerve tracts from the first month of age. These alterations were accompanied by significant lower levels of dimethyl arginine in both exposed groups, as compared with the controls, in the third and fourth months of age and exposure. These data demonstrate that myelin composition is a target of arsenic through interference with arginine methylation, and they suggest that disturbances in nervous transmission through myelinated fibers are an important component of arsenic neurotoxicity.",
Arsenic,1797785,"Micro-scale Distribution and Speciation of Arsenic in Peat Studied with µ-XRF and µ-XAS Abstract: Arsenic binding by sulfhydryl groups of natural organic matter (NOM) was recently identified as important As sequestration pathway in the naturally As-enriched minerotrophic peatland Gola di Lago, Switzerland. Here, we explore the micro-scale distribution, elemental correlations, and chemical speciation of As in the Gola di Lago peat. Thin sections of undisturbed peat samples from 0-37 cm and 200-249 cm depth were analyzed by synchrotron micro-X-ray fluorescence (µ-XRF) spectrometry and micro-X-ray absorption spectroscopy (µ-XAS). Additionally, peat samples were studied by bulk As, Fe, and S K-edge XAS. Micro-XRF analyses showed that As in the near-surface peat was mainly concentrated in 10-50 µm sized hotspots, identified by µ-XAS as realgar (?-As4S4). In the deep peat layer samples, however, As was more diffusely distributed and mostly associated with particulate NOM of varying decomposition stages. The NOM-associated As was present as trivalent As bound by sulfhydryl groups. Arsenopyrite (FeAsS) and arsenian pyrite (FeAsxS2-x) of &lt;25 µm size, which have escaped detection by bulk As and Fe K-edge XAS, were found as minor As species in the peat. Bulk S K-edge XAS revealed that the deep peat layers were significantly enriched in reduced organic S species. Our findings suggest an authigenic formation of realgar and arsenopyrite in strongly reducing microenvironments of the peat, and indicate that As(III)-NOM complexes are formed by the passive sorption of As(III) to NOM. This reaction appears to be favored by a combination of abundant reduced organic S and comparatively low As solution concentrations preventing the formation of secondary As-bearing sulfides.",
Arsenic,1340448,"Can one or two high doses of oral vitamin D3 correct insufficiency in a non-supplemented rheumatologic population? Abstract: We evaluated the effectiveness of supplementation with high dose of oral vitamin D3 to correct vitamin D insufficiency. We have shown that one or two oral bolus of 300,000 IU of vitamin D3 can correct vitamin D insufficiency in 50% of patients and that the patients who benefited more from supplementation were those with the lowest baseline levels. INTRODUCTION: Adherence with daily oral supplements of vitamin D3 is suboptimal. We evaluated the effectiveness of a single high dose of oral vitamin D3 (300,000 IU) to correct vitamin D insufficiency in a rheumatologic population. METHODS: Over 1 month, 292 patients had levels of 25-OH vitamin D determined. Results were classified as: deficiency &lt;10 ng/ml, insufficiency ?10 to 30 ng/ml, and normal ?30 ng/ml. We added a category using the IOM recommended cut-off of 20 ng/ml. Patients with deficient or normal levels were excluded, as well as patients already supplemented with vitamin D3. Selected patients (141) with vitamin D insufficiency (18.5 ng/ml (10.2-29.1) received a prescription for 300,000 IU of oral vitamin D3 and were asked to return after 3 (M3) and 6 months (M6). Patients still insufficient at M3 received a second prescription for 300,000 IU of oral vitamin D3. Relation between changes in 25-OH vitamin D between M3 and M0 and baseline values were assessed. RESULTS: Patients (124) had a blood test at M3. Two (2%) had deficiency (8.1 ng/ml (7.5-8.7)) and 50 (40%) normal results (36.7 ng/ml (30.5-5.5)). Seventy-two (58%) were insufficient (23.6 ng/ml (13.8-29.8)) and received a second prescription for 300,000 IU of oral vitamin D3. Of the 50/124 patients who had normal results at M3 and did not receive a second prescription, 36 (72%) had a test at M6. Seventeen (47%) had normal results (34.8 ng/ml (30.3-42.8)) and 19 (53%) were insufficient (25.6 ng/ml (15.2-29.9)). Of the 72/124 patients who receive a second prescription, 54 (75%) had a test at M6. Twenty-eight (52%) had insufficiency (23.2 ng/ml (12.8-28.7)) and 26 (48%) had normal results (33.8 ng/ml (30.0-43.7)). At M3, 84% patients achieved a 25-OH vitamin D level &gt;20 ng/ml. The lowest the baseline value, the highest the change after 3 months (negative relation with a correlation coefficient r?=?-0.3, p?=?0.0007). CONCLUSIONS: We have shown that one or two oral bolus of 300,000 IU of vitamin D3 can correct vitamin D insufficiency in 50% of patients.",
Arsenic,1355534,"CROSS-LINK FORMATION BETWEEN DNA AND NUCLEAR PROTEINS BY INVIVO AND INVITRO EXPOSURE OF CELLS TO DIMETHYLARSINIC ACID Abstract: Induction of pulmonary DNA/protein crosslinks by dimethylarsinic-acid (75605) (DMAA) was studied in mice. Induction of DNA/protein crosslinks in human lung cells was also investigated. Male ICR-mice were administered 0 or 1,500mg/kg DMAA orally. Selected mice were killed 0, 6, 12, 18, 24, or 36 hours (hr) later. The DNA was extracted from the lungs and analyzed for DNA/protein crosslinks by the proteinase-K/alkaline elution technique. Some of the DNA samples were treated with 6 molar (M) guanidine-hydrochloride (GHC) or irradiated with 500 roentgen X-rays before assay. L-132 cells, a human embryonic alveolar type-II cell line, were incubated with 12 millimolar (mM) DMAA in the presence or absence of 6M GHC or 3.8M hydroxylamine. The DNA was extracted after 0, 6, 9, or 12hr and analyzed for DNA/protein crosslinks. DMAA induced a time dependent increase in DNA/protein crosslinks as well as single strand breaks (SSBs) in mice. DNA/protein crosslinks were detected in X-irradiated and nonirradiated DNA after 6hr. SSBs were detected after 12hr. The SSBs in DMAA treated, nonirradiated DNA appeared to be repaired after 18hr. The crosslinks appeared to be sensitive to GHC as adding GHC to the assay mixtures decreased the crosslink yield. This suggested that the DNA/protein linkage sites occurred in phosphoserine and phosphothreonine residues of H1 histone and nonhistone proteins since these sites were known to be sensitive to GHC. DNA/protein crosslinks were induced in L-132 cells 6hr after DMAA treatment. The crosslinks were dissociated by both GHC and hydroxylamine. The authors conclude that the mechanism of DNA/protein crosslink induction by DMAA may involve, at least partially, formation of a complex containing H1 histone and nonhistone proteins. Induction of DNA/protein crosslinks by DMAA may involve a free radical mechanism, probably the dimethyl arsenic peroxyl radical.",
Arsenic,2298701,"Poisoned blood, Ghaa, and the infected body: Lay understandings of arsenicosis in rural Bangladesh Abstract: This article draws on ethnographic data from rural Bangladesh to examine how community members affected by arsenicosis understand, explain, and experience this deadly illness. Biomedically, arsenicosis has been described as a disease caused by drinking arsenic-contaminated water, and it is manifested through physiological complications such as symmetric hyperkeratosis of the palms and soles, cancer of the skin, kidney and lungs, and diseases of the blood vessels. This paper goes beyond such biomedical discourse and illustrates how arsenicosis has been vernacularized as ghaa in practice. It focuses on lay world views, logic, local knowledge systems, and sociocultural factors that shape popular understandings of the disease. This article is thus a contribution to our understanding of how arsenicosis, apart from its biomedical and clinical manifestations, is understood and experienced by affected individuals living within the particular sociocultural and ecological constraints of rural Bangladesh.",
Arsenic,710819,"Arsenic exposure in utero and nonepidermal proliferative response in adulthood in Tg.AC mice Abstract: To expand our knowledge on the transplacental carcinogenic potential of inorganic arsenic, pregnant Tg.AC mice received drinking water with 0, 42.5, or 85 ppm arsenite from gestation day 8 to 18. After birth, groups (n = 25) of offspring received topical 12-O-tetradecanoyl phorbol-13-acetate (TPA) (2 microg twice a week) for 36 weeks and were killed; nonskin tumors were assessed. Arsenic increased adrenal cortical adenomas (ACAs; 25%-29%) compared with control (0%) independent of TPA in all male groups. Arsenic increased urinary bladder (UB) hyperplasia in males, but only with TPA. Arsenic induced ACAs in all female groups (control 0%; arsenic 17%-26%). Arsenic-treated females had UB hyperplasia in most groups (control 0%; arsenic 26%-32%), with 2 UB papillomas. All arsenic-treated females had uterine hyperplasia (26%-40%; control 4%) independent of TPA, and 3 had uterine tumors. Thus, arsenic in utero rapidly induces ACAs and uterine and UB preneoplasias in Tg.AC mice, showing transplacental carcinogenic potential in yet another strain of mice.",
Arsenic,656885,"Upregulation of glutathione-related genes and enzyme activities in cultured human cells by sublethal concentrations of inorganic arsenic Abstract: Inorganic arsenic (iAs), a known human carcinogen, acts as a tumor promoter in part by inducing a rapid burst of reactive oxygen species (ROS) in mammalian cells. This causes oxidative stress and a subsequent increase in the level of cellular glutathione (GSH). Glutathione, a ubiquitous reducing sulfhydryl tripeptide, is involved in ROS detoxification and its increase may be part of an adaptive response to the oxidative stress. Glutathione related enzymes including glutathione reductase (GR) and glutathioneS-transferase (GST) also play key roles in these processes. In this study the regulatory effects of inorganic arsenite (As(III)) on the activities of GSH-related enzymes were investigated in cultured human keratinocytes. Substantial increases in GR enzyme activity and mRNA levels were shown in keratinocytes and other human cell lines after exposure to low, subtoxic, micromolar concentrations of As(III) for 24 h. Upregulation of GSH synthesis paralleled the upregulation of GR as shown by increases in glutamate-cysteine lyase (GCL) enzyme activity and mRNA levels, cystine uptake, and intracellular GSH levels. Glutathione S-transferase activity was also shown to increase slightly in keratinocytes, but not in fibroblasts or breast tumor cells. Overall the results show that sublethal arsenic induces a multicomponent response in human keratinocytes that involves upregulation of parts, but not all of the GSH system and counteracts the acute toxic effects of iAs. The upregulation of GR has not previously been shown to be an integral part of this response, although GR is critical for maintaining levels of reduced GSH.",
Arsenic,2149305,"HAZARDOUS SUBSTANCES IN DICALCIUM PHOSPHATE, LIMESTONE AND BOVINE BONE MEAL USED IN BRAZILIAN LIVESTOCK: DIOXINS, FURANS, BIPHENYLS, ARSENIC, THORIUM, URANIUM Abstract: ",
Arsenic,1034072,"Tissue retention of arsenic in rats fed witch founder or cacodylic acid Abstract: Weanling rats were fed one of five diets for 42 days either ad libitum or on a restricted-equalized feeding regimen. The five diets included a low arsenic control and a medium or high level of arsenic from either witch flounder (Glyptocephalus cynoglossus) tissue or cacodylic acid. Dietary arsenic in either form did not influence any of the biological indices of exposure examined except tissue arsenic levels. Retentions of arsenic in the livers and spleens of rats fed the highest level of fish arsenic (28.8 ppm) were about 7 and 2 times higher, respectively, than controls. Retentions of arsenic in the livers and spleens of rats fed the highest level of arsenic from cacodylic acid (22.1 ppm) were about 30 and 110 times higher, respectively, than controls. Retention of arsenic within the erythrocytes of rats fed the highest level of fish arsenic were equal to controls whereas it was about 130 times higher than controls among rats fed the highest level of arsenic as cacodylic acid. Apparently the chemical form of the arsenic in the edible tissue of witch flounder is uniquely metabolized by the rat compared to other arsenic forms.",
Arsenic,1250994,"Antagonistic toxicity of arsenate and cadmium in a freshwater amphipod (Gammarus pulex) Abstract: Because toxicants rarely occur alone in the environment, a major challenge in risk assessment is to address the combined effects of chemicals on aquatic organisms. This work is aimed at investigating the joint toxicity action of binary mixtures of cadmium and arsenate on Gammarus pulex. Individuals were exposed during 240 h to four single arsenate or cadmium concentrations and binary mixtures of these metals according to a complete factorial plane. Observed mortality in binary mixtures was compared to observed mortality in single arsenate or cadmium exposures. In addition, interactive effects (antagonistic, additive or synergistic) were evaluated using a predictive model for the theoretically expected interactive effect of chemicals. For all the tested concentration combinations, we observed an antagonist 'between-metals' interaction on G. pulex mortality. This antagonistic effect was more marked for the lowest than for the highest (i.e. 1502.0 ?g(AsV) L(-1) and 28.5 ?g(Cd) L(-1)) tested concentrations of individual metals in binary mixtures. Metal concentrations in body tissues were evaluated and were significantly lower in binary mixtures than in single metal exposures at similar concentration, especially for combinations corresponding to the highest concentrations of both metals (1502.0 ?g(AsV) L(-1) and 28.5 ?g(Cd) L(-1)). Results were discussed in terms of (1) mechanisms of uptake and bioconcentration and (2) relationships between metal concentration in gammarid body and observed toxicity.",
Arsenic,1019088,"Drinking water contaminants and childhood leukemia Abstract: We conducted a population-based case-control study to evaluate the relation between exposure to drinking water contaminants (total and specific trihalomethanes and certain metals and nitrates) and childhood acute lymphoblastic leukemia. We compared 491 cases 0-9 years of age with 491 controls. We developed a municipality-exposure matrix based on municipal and provincial historical data, a tapwater survey in 227 homes, and information about residential history. We used average level of exposure and cumulative average over the period as exposure indices, and we measured risk for the pregnancy period as well as for the postnatal period. We show that risks were generally not increased for the prenatal period nor with average levels of exposure. Postnatal cumulative exposure for total trihalomethanes at above the 95th percentile of the distribution for cases and controls was associated with an odds ratio of 1.54 (95% confidence interval = 0.78-3.03); for that same period, risk associated with exposure to chloroform was increased (odds ratio = 1.63; 95% confidence interval = 0.84-3.19) as well as that for exposure to zinc (odds ratio = 2.48; 95% confidence interval = 0.99-6.24). Risks were also increased for exposure to cadmium and arsenic, but not for other metals nor for nitrates.",
Arsenic,1015683,"Characterization and analyses of acid-extractable and leached trace elements in dental cements Abstract: Aims Determination of the elemental constitution and investigation of the total and leachable arsenic, chromium and lead in Portland cement, pure tricalcium silicate, Biodentine, Bioaggregate and mineral trioxide aggregate (MTA) Angelus. Methodology? The chemical composition of Portland cement, MTA Angelus, tricalcium silicate cement, Biodentine and Bioaggregate was determined using X-ray fluorescence (XRF). Measurements of arsenic, lead and chromium were taken with inductively coupled plasma-mass spectrometry (ICP-MS), following acid digestion on the hydrated material and on leachates of cements soaked in Hank's balanced salt solution (HBSS). Results? All the cements investigated had a similar oxide composition with the main oxide being calcium and silicon oxide. Both the Portland cement and MTA Angelus had an additional aluminum oxide. The dental cements included a radiopacifying material. All the materials tested had higher acid-extractable arsenic content than the level set by ISO 9917-1 (2007) and an acceptable level of lead. Regardless these high levels of trace elements present in the materials, the leaching in HBSS was minimal for all the dental material tested in contrast to the high levels displayed by Portland cement. Conclusions Dental materials based on tricalcium silicate cement and MTA Angelus release minimal quantities of trace elements when in contact with simulated body fluids. The results of acid extraction could be affected by nonspecific matrix effects by the cement.",
Arsenic,1070439,"Arsenic modulates heme oxygenase-1, interleukin-6, and vascular endothelial growth factor expression in endothelial cells: roles of ROS, NF-?B, and MAPK pathways Abstract: Chronic arsenic exposure has been linked to an increased risk of vascular diseases. To clarify the molecular mechanisms through which arsenic causes injuries to blood vessels, we analyzed the effects of arsenic trioxide on the cytotoxicity, intracellular reactive oxygen species (ROS), the expression of related genes, and signaling pathways involved in the SVEC4-10 mouse endothelial cells. Arsenic dose-dependently caused SVEC4-10 cell death, which is completely inhibited by ?-lipoic acid (LA), a thioreductant, but partially ameliorated by Tiron, a potent superoxide scavenger. The mRNA levels of heme oxygenase-1 (HO-1), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor (VEGF) were significantly increased by arsenic. The up-regulation of these can be blocked by LA instead of Tiron, suggesting ROS is not important in their increase. HO-1 competitive inhibitor zinc protoporphyrin improved the cytotoxicity of arsenic in an inverted-U dose-response curve, indicating the biphasic hormetic effect of HO-1. HO-1 siRNA decreased VEGF expression in response to arsenic. Arsenic exposure also enhanced NF-E2-related factor 2 (Nrf2) expression and increased activation of nuclear factor-?B (NF-?B). NF-?B inhibitor Bay 11-7082 reduced arsenic-mediated expression of HO-1 and IL-6. Selective blocking of the MAPK pathways with p38 inhibitor SB203580 significantly decreased arsenic-induced HO-1 and VEGF expression, while JNKs inhibitor SP600125 increased IL-6 expression. These results suggest that in arsenic-treated SVEC4-10 cells, HO-1 expression is mediated through Nrf2-, NF-?B-, and p38 MAPK-dependent signaling pathways and serves as an upstream regulator of VEGF. IL-6 expression is regulated by NF-?B and JNKs. In conclusion, oxidative stress may be associated with arsenic-induced cytotoxicity and endothelial gene up-regulation, but signaling transduction dominates the direct effects of ROS.",
Arsenic,1343972,Induction of 5-lipoxygenase in vascular endothelial cells in response to arsenic exposure Abstract: ,
Arsenic,710922,"Factors associated with arsenicosis and arsenic exposure status in Nepal: Implications from community based study Abstract: A significant public health problem due to exposure to arsenic via groundwater in communities of lowland Terai region of Nepal has issued forth need to assess the exposure status and factors associated with arsenicosis. We observed arsenical dermal manifestations and collected and assessed total arsenic content in tubewell water, urine, and hair samples of study subjects at arsenic affected communities in Nawalparasi district of Nepal. The explanatory variables associated with arsenicosis were elevated arsenic in tubewell, male gender and increased age (P < 0.05). 67% (73/109) and 66% (77/117) of subjects exceeded the normal urinary and hair arsenic levels respectively. Among them 52% (57/109) and 47% (55/117) exceeded normal urinary and hair arsenic levels having no arsenical dermal manifestations. Males and symptomatic cases had significantly higher hair arsenic levels (P < 0.05). We also observed significant positive correlation of both urine and hair arsenic levels to tubewell arsenic levels (r = 0.27, 0.37, P < 0.01) and negative correlation of urine arsenic levels with the age of the subjects (r = -0.18, P = 0.06). We conclude that elucidating factors associated with arsenicosis could be of prime importance in intervention and preventive measures. In arsenic affected communities of Nepal exposure to arsenic is still a major problem despite mitigation efforts and the potential for sub-clinical effects in exposed population is high.",
Arsenic,2279285,"Enhanced removal of arsenic from a highly laden industrial effluent using a combined coprecipitation/nano-adsorption process Abstract: Effective arsenic removal from highly laden industrial wastewater is an important but challenging task. Here, a combined coprecipitation/nano-adsorption process, with ferric chloride and calcium chloride as coprecipitation agents and polymer-based nanocomposite as selective adsorbent, has been validated for arsenic removal from tungsten-smelting wastewater. On the basis of operating optimization, a binary FeCl3 (520 mg/L)-CaCl2 (300 mg/L) coprecipitation agent could remove more than 93 % arsenic from the wastewater. The resulting precipitate has proved environmental safety based on leaching toxicity test. Fixed-bed column packed with zirconium or ferric-oxide-loaded nanocomposite was employed for further elimination of arsenic in coprecipitated effluent, resulting in a significant decrease of arsenic (from 0.96 to less than 0.5 mg/L). The working capacity of zirconium-loaded nanocomposite was 220 bed volumes per run, much higher than that of ferric-loaded nanocomposite (40 bed volumes per run). The exhausted zirconium-loaded nanocomposite could be efficiently in situ regenerated with a binary NaOH-NaCl solution for reuse without any significant capacity loss. The results validated the combinational coprecipitation/nano-adsorption process to be a potential alternative for effective arsenic removal from highly laden industrial effluent.",
Arsenic,2149284,Assessing Molybdenum Adsorption onto an Industrial Soil and Iron Minerals Abstract: ,
Arsenic,627313,"Serum levels of the extracellular domain of the epidermal growth factor receptor in individuals exposed to arsenic in drinking water in Bangladesh Abstract: Epidermal growth factor receptor-dependent mechanisms have been implicated in growth signal transduction pathways that contribute to cancer development, including dermal carcinogenesis. Detection of the extracellular domain of the epidermal growth factor receptor (EGFR ECD) in serum has been suggested as a potential biomarker for monitoring this effect in vivo. Arsenic is a known human carcinogen, producing skin and other malignancies in populations exposed through their drinking water. One such exposed population, which we have been studying for a number of years, is in Bangladesh. The purpose of this study was to examine the EGFR ECD as a potential biomarker of arsenic exposure and/or effect in this population. Levels of the EGFR ECD were determined by enzyme-linked immunosorbent assay in the serum samples from 574 individuals with a range of arsenic exposures from drinking water in the Araihazar area of Bangladesh. In multiple regression analysis, serum EGFR ECD was found to be positively associated with three different measures of arsenic exposure (well water arsenic, urinary arsenic and a cumulative arsenic index) at statistically significant levels (p&lt;or=0.034), and this association was strongest among the individuals with arsenic-induced skin lesions (p &lt;or= 0.002). When the study subjects were stratified in tertiles of serum EGFR ECD levels, the risk of skin lesions increased progressively for each increase in all three arsenic measures (also stratified in tertiles) and this increasing risk became more pronounced among subjects within the highest tertile of EGFR ECD levels. These results suggest that serum EGFR ECD levels may be a potential biomarker of effect of arsenic exposure and may indicate those exposed individuals at greatest risk for the development of arsenic-induced skin lesions.",
Arsenic,1358206,An experimental investigation of the &quot;ring hypothesis&quot; of arsenical toxicity Abstract: ,
Arsenic,1357449,"Chromosomal Aberrations in Humans Exposed to Arsenic in the Srednogorie Area, Bulgaria Abstract: The induction of chromosomal aberrations due to arsenic (7440382) (As) in humans living close to a copper smelter in the Srednogorie area of Bulgaria was investigated. Heavy air pollution and soil contamination had occurred since the smelter started operation in 1959. In the nearby River Topolnitza, downstream As concentrations ranged from 0.75 to 1.5 parts per million (ppm) during 1987 to 1990. In April 1991, blood was collected from five women from the area, and four women from an unexposed region. All subjects were aged 38 to 55 years. As concentration in hair and toe nails were tested. Blood samples were collected and micronuclei were scored in at least 1000 lymphocytes per individual. Results showed a significant increase in micronuclei of lymphocytes in exposed individuals (29 to 57 versus 12 to 17 in referents). The hair and toe nail As levels were correspondingly higher than in the unexposed individuals (as high as 3.9ppm in hair and 7.7ppm in toe nails of exposed individuals versus 0.08ppm and 0.41ppm in unexposed subjects). The authors conclude that inorganic As is clastogenic in humans, and probably exerts its effects by inhibiting DNA repair.",
Arsenic,8426,"Studies of morbidity near a copper smelter Abstract: Children living near a copper smelter in Tacoma, Washington, have been shown to have increased levels of urinary and hair arsenic. Studies of hearing, blood status and school attendance in exposed and nonexposed children failed to detect any differences in these parameters.",
Arsenic,2347651,"Th(As(III)4As(V)4O18): a Mixed-Valent Oxoarsenic(III)/arsenic(V) Actinide Compound Obtained under Extreme Conditions Abstract: A high-temperature/high-pressure method was employed to investigate phase formation in the Th(NO3)4·5H2O-As2O3-CsNO3 system. It was observed that an excess of arsenic(III) in starting system leads to the formation of Th(As(III)4As(V)4O18), which is representative of a rare class of mixed-valent arsenic(III)/arsenic(V) compounds. This compound was studied with X-ray diffraction, energy-dispersive X-ray, and Raman spectroscopy methods. Crystallographic data show that Th(As(III)4As(V)4O18) is built from (As(III)4As(V)4O18)(4-) layers connected through Th atoms. The arsenic layers are found to be isoreticular to those in previously reported As2O3 and As3O5(OH), and the geometric differences between them are discussed. Bands in the Raman spectrum are assigned with respect to the presence of AsO3 and AsO4 groups.",
Arsenic,1597357,"Arsenic-stimulated lipolysis and adipose remodeling is mediated by G-protein-coupled receptors Abstract: Arsenic in drinking water promotes a number of diseases that may stem from dysfunctional adipose lipid and glucose metabolism. Arsenic inhibits adipocyte differentiation and promotes insulin resistance; however, little is known of the impacts of and mechanisms for arsenic effects on adipose lipid storage and lipolysis. Based on our earlier studies of arsenic signaling mechanisms for vascular remodeling and inhibition of adipogenesis, we investigated the hypothesis that arsenic acts through specific adipocyte G-protein coupled receptors to promote lipolysis and decrease lipid storage. We first demonstrated that 5 wk exposure of mice to 100 ?g/L of arsenic in drinking water stimulated epididymal adipocyte hypertrophy, reduced the adipose tissue expression of perilipin (a lipid droplet coat protein), and increased perivascular ectopic fat deposition in skeletal muscle. Incubating adipocytes, differentiated from adipose-derived huMSC, with arsenic stimulated lipolysis and decreased both Nile red positive lipid droplets and perilipin expression. Arsenic-stimulated lipolysis was not associated with increased cAMP levels. However, pre-incubation of adipocytes with the Gi-inhibitor, Pertussis toxin, attenuated As(III)-stimulated lipolysis and lipid droplet loss. Antagonizing Gi-coupled endothelin-1 type A and B receptors (EDNRA/EDNRB) also attenuated arsenic effects, but antagonizing other adipose Gi-coupled receptors that regulate fat metabolism was ineffective. The endothelin receptors have different roles in arsenic responses, since only EDNRA inhibition prevented arsenic-stimulated lipolysis, but antagonists to either receptor protected lipid droplets and perilipin expression. These data support a role for specific G-protein coupled receptors in arsenic signaling for aberrant lipid storage and metabolism that may contribute to the pathogenesis of metabolic disease caused by environmental arsenic exposures.",1
Arsenic,2279401,"Toxic Metal Concentrations in Mainstream Smoke from Cigarettes Available in the USA Abstract: Public health officials and leaders of 168 nations have signaled their concern regarding the health and economic impacts of smoking by becoming signatory parties to the World Health Organization Framework Convention on Tobacco Control (FCTC). One of FCTC's purposes is to help achieve meaningful regulation for tobacco products in order to decrease the exposure to harmful and potentially harmful constituents (HPHCs) delivered to users and those who are exposed to secondhand smoke. Determining baseline delivery ranges for HPHCs in modern commercial tobacco products is crucial information regulators could use to make informed decisions. Establishing mainstream smoke delivery concentration ranges for toxic metals was conducted through analyses of total particulate matter (TPM) collected with smoking machines using standard smoking regimens. We developed a rapid analytical method with microwave digestion of TPM samples obtained with smoking machines using electrostatic precipitation under the ISO and Intense smoking regimens. Digested samples are analyzed for chromium, manganese, cobalt, nickel, arsenic, cadmium and lead using inductively coupled plasma-mass spectrometry. This method provides data obtained using the ISO smoking regimen for comparability with previous studies as well as an Intense smoking regimen that represents deliveries that fall within the range of human exposure levels to toxic metals.",
Arsenic,1345850,"Measuring and Modeling Atmospheric Arsenic Pollutants, Total As, As(III), and As(V), at Five Characteristic Sampling Sites Abstract: This investigation determines ambient air arsenic (As), As(III), and As(V) concentrations in total suspended particulates (TSP) and dry deposition. Calculated/measured dry deposition flux ratios of ambient air As, As(III) and As(V) were evaluated using two dry deposition models at five characteristic sampling sites during 2009-2010. The highest average concentrations of As, As(III) and As(V) in TSP and dry deposition were measured at the Quan-xing industrial sampling site during August-January. The Quan-xing site, with many industrial factories under process around there regions, its air is extremely polluted. In addition, the average dry deposition velocities for ambient air total arsenic (As) at Bei-shi, Chang-hua, He-mei, Quan-xing and Gao-mei were 0.60 (cm/sec), 0.57 (cm/sec), 0.73 (cm/sec), 0.67 (cm/sec) and 0.66 (cm/sec), respectively at these five characteristic sampling sites. <br> <br>The highest average seasonal variation for As, As(III) and As(V) in TSP and dry deposition were in winter and fall due to emissions from fossil fuel combustion by the nearby Taichung Thermal Power Plant (TTPP) and for household heating.",
Arsenic,2278417,"The influence of arsenate and phosphate exposure on arsenic uptake, metabolism and species formation in the marine phytoplankton Dunaliella tertiolecta Abstract: The influence of As(V) (50 mu g L-1 &amp; 2 mu g L-1) and PO43- (3 mg L-1 &amp; 0.12 mg L-1) exposures on arsenic cycling by the marine phytoplankton Dunaliella tertiolecta was investigated both separately and in combination. Total arsenic concentrations in D. tertiolecta tissue ranged from 8 to 10 mu g g(-1) when exposed to 50 mu g L-1 As(V), and 2-4 mu g g(-1) when exposed to 2 mu g L-1 As(V), with PO43- exposure having little to no influence on total arsenic concentrations. <br> <br>Arsenic was evenly distributed (approximate to 33%) between the three major biochemical cell fractions (lipid, water, residue) in cultures exposed to high As(V) :high PO43- concentrations. Under low As(V) :high PO43- exposures arsenic was predominantly lipid-soluble (40-55%) and residue bound (30-40%). When exposed to high As(V):low PO43- concentrations arsenic was predominantly residue bound (50-70%) and lipid-soluble (20-40%), whilst under low As(V):low PO43- exposures arsenic was predominantly residue bound (75-80%). <br> <br>As(V) was the dominant arsenic species present in the water-soluble cell fractions of all D. tertiolecta cultures. Under high PO43- concentrations As(V) accounted for greater than 93% of the extractable water-soluble arsenic, with As(III) the only other species detected. Conversely, under low PO43- concentrations As(V) accounted for between 66 and 71% of the extractable arsenic with As(III) (16-26%) and PO4-riboside (8-13%) present. <br> <br>Under high As(V) :high PO43- concentrations As (V) was the major arsenic species in hydrolysed lipid extracts accounting for approximately 56% of the extractable arsenic, with Gly-riboside (26%), PO4-riboside (13%) and As(III) (5%) also present. Under low As(V):high PO43- conditions As(V) only accounted for approximately 18% of the extractable arsenic with Gly-riboside (44%) and PO4-riboside (38%) more prominent Under low PO43- conditions Gly-riboside was the major arsenic species (84-92%) irrespective of As(V) exposure with As(V) (8-10%) and PO4-riboside (6%) also present. <br> <br>This study demonstrates that D. tertiolecta alters its arsenic and nutrient cycling processes depending on the chemical composition of the culture media or surrounding environment. Future research should endeavour to culture laboratory phytoplankton at nutrient and arsenic concentrations that mimic the natural environment to ensure that observations generated in laboratory experiments can be used to describe arsenic cycling in marine systems. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,1016386,"An empirical model of perceived mortality risks for selected U.S. Arsenic hot spots Abstract: Researchers have long recognized that subjective perceptions of risk are better predictors of choices over risky outcomes than science-based or experts' assessments of risk. More recent work suggests that uncertainty about risks also plays a role in predicting choices and behavior. In this article, we develop and estimate a formal model for an individual's perceived health risks associated with arsenic contamination of his or her drinking water. The modeling approach treats risk as a random variable, with an estimable probability distribution whose variance reflects uncertainty. The model we estimate uses data collected from a survey given to a sample of people living in arsenic-prone areas in the United States. The findings from this article support the fact that scientific information is essential to explaining the mortality rate perceived by the individuals, but uncertainty about the probability remains significant.",
Arsenic,1019615,"Different effects of inorganic and dimethylated arsenic compounds on cell morphology, cytoskeletal organization, and DNA synthesis in cultured Chinese hamster V79 cells Abstract: Changes in cytoskeletal organization of cultured V79 cells exposed to arsenite and dimethylarsinic acid (DMAA), a methylated derivative of inorganic arsenics, and related changes, such as mitotic arrest and induction of multinucleated cells, were investigated in comparison with their effects on DNA synthesis. DMAA caused mitotic arrest and induction of multinucleated cells with a delay of 12 h relative to the mitotic arrest. By contrast, arsenite at equitoxic concentrations to DMAA was less effective than DMAA in causing mitotic arrest and in inducing multinucleated cells. Post-mitotic incubation of cells arrested in metaphase by 6 h incubation with 10 mM DMAA showed that the incidence of multinucleated cells increased conversely with a rapid decrease in metaphase cells. This suggests that metaphase-arrested cells can escape from metaphase, resulting in the appearance of multinucleated cells. The mitotic arrest caused by DMAA was accompanied by disruption of the microtubule network. By contrast, both arsenite and DMAA did not cause disorganization of actin stress fibers even when incubated at concentrations that caused a marked retardation of cell growth. Cells exposed to arsenite for 6 h showed marked inhibition of DNA synthesis, whereas inhibition by DMAA was not observed. When incubation was prolonged by 18 h, the arsenite-induced inhibition of DNA synthesis was mitigated. By contrast, inhibition of DNA synthesis by DMAA occurred in parallel with an increase in the population of mitotic cells. These results suggest that DMAA caused growth retardation and morphological changes via disruption of the microtubule network, and that arsenite-induced retardation of cell growth and inhibition of DNA synthesis were not attributable to the cytoskeletal changes.",
Arsenic,1017343,"Chronic exposure to arsenic causes increased cell survival, DNA damage, and increased expression of mitochondrial transcription factor A (mtTFA) in human prostate epithelial cells Abstract: Arsenic is a known carcinogen, and its exposure is associated with cancers in multiple target organs including the prostate. Whether arsenic causes cancer by increased cell proliferation or cell survival is not clear. Additionally, mitochondria have been shown to play important roles in arsenic-induced DNA damage and carcinogenesis. However, the mechanism of mitochondrial involvement in arsenic-induced cancer is not clear. Therefore, the objectives of this study were to investigate the effect of arsenic on cell proliferation/survival and genotoxicity, and to determine the effect of arsenic on the expression of mitochondrial transcription factor A (mtTFA) in human prostate epithelial cells, RWPE-1. Results of this study revealed that chronic exposure to arsenic causes increased cell survival. Arsenic also induced nuclear DNA damage and mutations in mitochondrial DNA. Expressions of DNA repair genes ERCC6, XPC, OGG1, and reactive oxygen species (ROS) scavenger MnSOD was also altered in arsenic-exposed cells. Arsenic concentration-dependent increased expression of mtTFA and its regulator NRF-1 was observed in arsenic-exposed cells, suggesting that arsenic regulates mitochondrial activity through an NRF-1-dependent pathway. In summary, this study suggests that chronic exposure to arsenic causes DNA damage and increased cell survival that may ultimately result in neoplastic transformation of human prostate epithelial cells. Additionally, this study also provides evidence that arsenic controls mitochondrial function by regulating mtTFA expression.",
Arsenic,1019696,"Urine arsenic concentrations in healthy adults as indicators of environmental contamination: relation with some pathologies Abstract: Arsenic concentrations were determined in 126 urine samples by hydride generation atomic absorption spectrometry. Samples were mineralized with nitric acid in a thermostated mineralization block. This technique was compared with a method that involves mineralization in a microwave digestion bomb. A mean recovery percentage of 100.80 +/- 5.57% was obtained. The relative standard deviation ranged from 1.7 to 10.52%. It was found that subject sex and age did not affect urine As levels (P &gt; 0.05). The mean urine As levels in patients with hepatic injury (4.24 +/- 1.98 micrograms/l), diabetes (3.44 +/- 2.36 micrograms/l) and myocardial infarction (3.64 +/- 1.85 micrograms/l) were not statistically different (P &gt; 0.05) to that found in the control group (healthy subjects) (3.68 +/- 2.27 micrograms/l). This result could be related to the fact that the regulation of As in the human organism is independent of these diseases. Measured As concentrations in the eight basic health zones of the study area were not statistically different (P &gt; 0.01). This fact demonstrates the existence of a similarly low environmental As distribution in coastal and mountainous zones.",
Arsenic,1024426,"Urinary 8-hydroxy-2'-deoxyguanosine in inhabitants chronically exposed to arsenic in groundwater in Cambodia Abstract: Arsenic concentrations in hair and urine, and urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were examined for inhabitants of the Mekong Basin in Kratie Province, Cambodia. Also, the arsenic levels of tube-well water were determined. Total arsenic concentrations in tube-well water ranged from &lt;1 to 886 microg L(-1), and 44.8% of these exceeded the WHO drinking water guideline of 10 microg L(-1). Elevated levels of arsenic were observed in the human hair and urine, and also a significant positive correlation was observed between the concentrations in hair and urine. These results suggest that the inhabitants are chronically exposed to arsenic through drinking the tube-well water. Levels of urinary 8-OHdG were higher for the subjects with higher arsenic levels in hair and urine, suggesting that induction of oxidative DNA damage was caused by chronic exposure to arsenic in tube-well water for the inhabitants in Kratie Province. To our knowledge, this is the first report on the oxidative DNA damage caused by chronic exposure to arsenic in groundwater for the inhabitants in Cambodia.",
Arsenic,1021466,"Mathematical model insights into arsenic detoxification Abstract: <strong>BACKGROUND: </strong>Arsenic in drinking water, a major health hazard to millions of people in South and East Asia and in other parts of the world, is ingested primarily as trivalent inorganic arsenic (iAs), which then undergoes hepatic methylation to methylarsonic acid (MMAs) and a second methylation to dimethylarsinic acid (DMAs). Although MMAs and DMAs are also known to be toxic, DMAs is more easily excreted in the urine and therefore methylation has generally been considered a detoxification pathway. A collaborative modeling project between epidemiologists, biologists, and mathematicians has the purpose of explaining existing data on methylation in human studies in Bangladesh and also testing, by mathematical modeling, effects of nutritional supplements that could increase As methylation.<br /><br /><strong>METHODS: </strong>We develop a whole body mathematical model of arsenic metabolism including arsenic absorption, storage, methylation, and excretion. The parameters for arsenic methylation in the liver were taken from the biochemical literature. The transport parameters between compartments are largely unknown, so we adjust them so that the model accurately predicts the urine excretion rates of time for the iAs, MMAs, and DMAs in single dose experiments on human subjects.<br /><br /><strong>RESULTS: </strong>We test the model by showing that, with no changes in parameters, it predicts accurately the time courses of urinary excretion in mutiple dose experiments conducted on human subjects. Our main purpose is to use the model to study and interpret the data on the effects of folate supplementation on arsenic methylation and excretion in clinical trials in Bangladesh. Folate supplementation of folate-deficient individuals resulted in a 14% decrease in arsenicals in the blood. This is confirmed by the model and the model predicts that arsenicals in the liver will decrease by 19% and arsenicals in other body stores by 26% in these same individuals. In addition, the model predicts that arsenic methyltransferase has been upregulated by a factor of two in this population. Finally, we also show that a modification of the model gives excellent fits to the data on arsenic metabolism in human cultured hepatocytes.<br /><br /><strong>CONCLUSIONS: </strong>The analysis of the Bangladesh data using the model suggests that folate supplementation may be more effective at reducing whole body arsenic than previously expected. There is almost no data on the upregulation of arsenic methyltransferase in populations chronically exposed to arsenic. Our model predicts upregulation by a factor of two in the Bangladesh population studied. This prediction should be verified since it could have important public health consequences both for treatment strategies and for setting appropriate limits on arsenic in drinking water. Our model has compartments for the binding of arsenicals to proteins inside of cells and we show that these comparments are necessary to obtain good fits to data. Protein-binding of arsenicals should be explored in future biochemical studies.",
Arsenic,2345759,"Assessment of regional groundwater quality based on health risk in Xi'an region, PR China Abstract: To reveal the relationship between the dynamic change Of groundwater quality and human health, this paper uses the shallow groundwater in Xi'an region as the research object, introduces the health risk assessment into the dynamic study of regional groundwater and finally implements a dynamic assessment of the health risk associated with regional groundwater. The results show that the primary carcinogen in the shallow groundwater of Xi'an region is arsenic, with a carcinogenic risk exceeding the standard rate by 26.3 %. The primary non-carcinogenic chronic toxicity is nitrate, With a 50.66 % non-carcinogenic toxicity risk among the total non-carcinogenic risks. Besides,,even for the:groundwater satisfying the national standards for drinking water, its arsenic and nitrate pose potential risks for human health. There are generally declining tendencies-for both the carcinogenic risk and the non-carcinogenic chronically toxic risk caused by toxic substances in groundwater, with exceptions for certain substances which Still exceed maximum acceptable values recommended by US EPA. Therefore, it is extremely necessary for long-term observations and health risk management, especially in those high-risk regions with poorer groundwater quality. In that way, the adverse influences by Chemical substances in the groundwater will be reduced for the health of drinking populations.",
Arsenic,656667,"Molecular interaction between arsenic hydrate microcrystals and the cell-surface endopeptidase CD10 (neprilysin) - a possible link to the development of renal and cutaneous malignancies upon occupational exposure to arsenic compounds? Abstract: Arsenic poisoning has become a worldwide public health concern since arsenic is recognized as a human carcinogen although the detailed mechanisms of carcinogenesis related to arsenic exposure are not completely understood at present. In particular, the skin and the kidneys are prone to neoplastic transformation upon occupational exposure of the human body to inorganic arsenic compounds. The cell-surface endopeptidase CD10 is variably expressed in cutaneous and renal malignancies, and due to this expression profile, might theoretically be implicated in arsenic-induced skin and renal neoplasias. From the functional point of view, CD10 conveys important anti-tumorigenic effects brought about by the inactivation of neuropeptide growth factors implicated in cancer progression. Placing the focus on the structural composition of arsenic hydrate microcrystals encountered in the cellular microenvironment, the present hypothesis suggests so far neglected molecular interactions between arsenic microcrystals and membrane-bound CD10 to be implicated in arsenic-induced carcinogenesis.",
Arsenic,1579359,"Genotypic difference in temporal variation of arsenic accumulation and expression of silicon efflux transporter (LSi2) gene in the field grown rice Abstract: Rice-straw accumulated significantly higher amount of arsenic than grain but linear correlation did not exist among straw and grain accumulation. A popular cultivar, IR64 accumulated majority of grain arsenic in the husk, rather than brown rice, both at kharif and boroseason. Till two weeks after fertilization (dough stage) arsenic accumulation in spikelet remains same for all the eight genotypes. Variation of total arsenic in grain of eight rice genotypes started during dough stage to maturity. Expression of arsenite efflux transporter,LSi2, in root and stem was not correlated with arsenic accumulation at brown rice but expression in grain showed stronger correlation (r=0.87) with accumulation in husk among these genotypes.",
Arsenic,1070487,"Predicting the risk of arsenic contaminated groundwater in Shanxi Province, Northern China Abstract: Shanxi Province is one of the regions in northern China where endemic arsenicosis occurs. In this study, stepwise logistic regression was applied to analyze the statistical relationships of a dataset of arsenic (As) concentrations in groundwaters with some environmental explanatory parameters. Finally, a 2D spatial model showing the potential As-affected areas in this province was created. We identified topography, gravity, hydrologic parameters and remote sensing information as explanatory variables with high potential to predict high As risk areas. The model identifies correctly the already known endemic areas of arsenism. We estimate that the area at risk exceeding 10?gL(-1) As occupies approximately 8100km(2) in 30 counties in the province.",
Arsenic,56429,"Effects of low-level lead and arsenic exposure on copper smelter workers Abstract: An analysis of reported symptoms and their relationship with indicators of lead absorption--blood lead (Pb-B) and zinc protoporphyrin (ZPP)--and of arsenic absorption--urinary arsenic (As-U)--was undertaken among 680 active copper smelter workers. Lead and arsenic absorption in the copper smelter employees were characterized by the median values of 30.4 micrograms/dl for Pb-B, 41.5 micrograms/dl for ZPP, and 26 micrograms/L for As-U. Blood lead was 40 micrograms/dl or higher in 16.7% of cases, ZPP was 50 micrograms/dl or higher in 31.2%, and urinary arsenic was 50 micrograms/L or higher in 16.4% of currently active copper smelter workers. The number of reported symptoms (from a total of 14 symptoms) increased with ZPP levels; the relationship with Pb-B was less marked. Arsenic contributed relatively little. Mean Pb-B, ZPP, and As-U levels for subjects reporting each of the 14 symptoms were compared with those of subjects who did not report the symptoms. Mean Pb-B was found to differ significantly for one symptom, fatigue. Significant differences in mean ZPP levels were found for fatigue, sleep disturbances, weakness, paresthesia, and joint pain. Prevalence rates for these symptoms rose more markedly with increasing ZPP than with Pb-B levels. The results indicate a relationship between certain CNS and musculo-skeletal symptoms and increased lead absorption in this population. Adherence to exposure standards that preclude undue lead absorption and appropriate biological monitoring including ZPP levels, are necessary to prevent adverse, especially long-term, health effects.",
Arsenic,1337315,"Chronic arsenic exposure in nanomolar concentrations compromises wound response and intercellular signaling in airway epithelial cells Abstract: Paracrine ATP signaling in the lung epithelium participates in a variety of innate immune functions including mucociliary clearance, bactericide production and as an initiating signal in wound repair. We evaluated the effects of chronic low-dose arsenic relevant to U.S. drinking water standards (i.e. 10 ppb (130 nM)) on airway epithelial cells. Immortalized human bronchial epithelial cells (16HBE14o-) were exposed to 0, 130, or 330 nM arsenic (as Na-arsenite) for 4 - 5 weeks and examined for wound repair efficiency and ATP-mediated Ca(2+) signaling. We found chronic arsenic exposure at these low doses slows wound repair and reduces ATP-mediated Ca(2+) signaling. We further show that arsenic compromises ATP-mediated Ca(2+) signaling by altering both Ca(2+) release from intracellular stores (via metabotropic P2Y receptors) and Ca(2+) influx mechanisms (via ionotropic P2X receptors). To better model the effects of arsenic on ATP-mediated Ca(2+) signaling under conditions of natural exposure, we cultured tracheal epithelial cells obtained from mice exposed to control or 50 ppb Na-arsenite supplemented drinking water for four weeks. Tracheal epithelial cells from arsenic-exposed mice displayed reduced ATP-mediated Ca(2+) signaling dynamics similar to our in vitro chronic exposure. Our findings demonstrate that chronic arsenic exposure at levels that are commonly found in drinking water (i.e. 10 - 50 ppb) alters cellular mechanisms critical to airway innate immunity.",
Arsenic,1356873,"Potentiation Of Mitochondrial Susceptibility, Oxidative Stress And NF-KB Signaling Following Chemical Mixture (Lead And Arsenic)-Induced Neurotoxicity Abstract: Lead (Pb) and arsenic (As) as neurotoxic metals, can produce a cognitive deficits, central and peripheral neuropathy in human. The mechanism responsible for these effects on the central nervous system is not clear. Previous studies in animals and cell culture models show that both arsenic and lead can produce neuronal cell death that may be related to oxidative stress. In the present study, the vulnerability of the cultured dopaminergic neurons to Pb and As mixture by characterizing the cytotoxic interaction between Pb and As and then examined the underlying mechanism. In mesencepahlic cells (dopaminergic cell lines), lead (0, 10, 20, 50 and 100 uM) and arsenic (0, 10, 20, 50, and 100 uM) produced minimal reactive oxygen species (ROS) dose dependently over 24 hr period. When cells were exposed concurrently to these metals, a burst of ROS was noted. To test the role of mitochondrial viability in response to Pb and As mixture, MTT up-take assay were done as a mitochondrial marker in cultured neurons. Cells that were exposed concurrently to Pb and As showed reduced MTT-up-take in dose dependent manner over the control and Pb and As alone exposed cells. Further, incubation of cells with Pb and As induced alteration in redox sensitive transcription factor, NF-kB activity and its significant change over the Pb and As alone have been analyzed and results will be discussed with cell death mechanism. This explains the neurochemical basis of the cells vulnerability to chemical mixture induced toxicity and determine if any antioxidants prevent cytotoxicity.",
Arsenic,1509322,"Screening Indian mustard genotypes for phytoremediating arsenic-contaminated soils Abstract: Ten Indian mustard (Brassica juncea L.) genotypes were screened for their phytoremediation potential for arsenic (As) contaminated water under laboratory-controlled conditions. The genotypes were grown in a hydroponic chamber for 20 days in 250-mL beakers containing As-contaminated water. During plant development, changes in plant growth, biomass, and total As were evaluated. Of the 10 genotypes (Pusa Agrani, BTO, Pusa Kranti, Pusa Bahar, Pusa Bold, Pusa Basant, Pusa Jai Kisan, Arka Vardhan, Varuna, and Vaibhav) Pusa Jai Kisan was the most effective in phytoremediating As-contaminated water under hydroponic conditions. This will provide new information for Indian mustard genotypes for phytoremediating As-contaminated soils.",
Arsenic,1027536,Arsenic exposure through groundwater to the rural and urban population in the Allahabad-Kanpur track in the upper Ganga plain Abstract: This preliminary study reports for the first time that part of the rural population in the Allahabad district and the urban population in the Suklaganj-Kanpur of Unnao district in the Allahabad-Kanpur track of the upper Ganga plain are drinking and using for agricultural irrigation arsenic contaminated water (maximum arsenic concentrations in drinking water and urine are 707 and 1744 microg L(-1) respectively) mostly from shallow hand tube-wells (depth 7.5-40 m) without knowing that these are arsenic contaminated.,
Arsenic,1794767,"Adsorption and desorption characteristics of diphenylarsenicals in two contrasting soils Abstract: Diphenylarsinic acid (DPAA) is formed during the leakage of aromatic arsenic chemical weapons in soils, is persistent in nature, and results in arsenic contamination in the field. The adsorption and desorption characteristics of DPAA were investigated in two typical Chinese soils, an Acrisol (a variable-charge soil) and a Phaeozem (a constant-charge soil). Their thermodynamics and some of the factors influencing them (i.e., initial pH value, ionic strength and phosphate) were also evaluated using the batch method in order to understand the environmental fate of DPAA in soils. The results indicate that Acrisol had a stronger adsorption capacity for DPAA than Phaeozem. Soil DPAA adsorption was a spontaneous and endothermic process and the amount of DPAA adsorbed was affected significantly by variation in soil pH and phosphate. In contrast, soil organic matter and ionic strength had no significant effect on adsorption. This suggests that DPAA adsorption may be due to specific adsorption on soil mineral surfaces. Therefore, monitoring the fate of DPAA in soils is recommended in areas contaminated by leakage from chemical weapons.",
Arsenic,1579300,"Arsenate (As V) in water: Quantitative sensitivity relationships among biomarker, ecotoxicity and genotoxicity endpoints Abstract: It is useful to test ecotoxicity and genotoxicity endpoints in the environmental impact assessment. Here, we compare and discuss ecotoxicity and genotoxicity effects in organisms in response to exposure to arsenate (As V) in solution. Eco(geno)toxicity responses in Aliivibrio fischeri, Lytechinus variegatus, Daphnia magna, Skeletonema costatum and Vicia faba were analyzed by assessing different endpoints: biomass growth, peroxidase activity, mitotic index, micronucleus frequency, and lethality in accordance with the international protocols. Quantitative sensitivity relationships (QSR) between these endpoints were established in order to rank endpoint sensitivity. The results for the QSR values based on the lowest observed effect concentration (LOEC) ratios varied from 2 (for ratio of root peroxidase activity to leaf peroxidase activity) to 2286 (for ratio of higher plant biomass growth to root peroxidase activity). The QSR values allowed the following sensitivity ranking to be established: higher plant enzymatic activity&gt;daphnids?echinoderms&gt;bacteria?algae&gt;higher plant biomass growth. The LOEC values for the mitotic index and micronucleus frequency (LOEC=0.25mgAsL(-1)) were similar to the lowest LOEC values observed in aquatic organisms. This approach to the QSR of different endpoints could form the basis for monitoring and predicting early effects of pollutants before they give rise to significant changes in natural community structures.",
Arsenic,1936086,"Health risk from As contaminated fish consumption by population living around River Chenab, Pakistan Abstract: We analyzed six edible fish species (Securicola gora; Cirrhinus reba; Rita rita; Sperata sarvari; Culpisoma naziri and Labeo kalbasu) to evaluation As contamination. These species were caught from the River Chenab of Pakistan. The aim of this study was to determine the concentration of arsenic (As) and the antioxidant response in the muscle, liver and gills. The sampling sites were divided into agricultural, industrial and urban land uses. Although, the highest concentration of As, and the antioxidant activity was found in the liver, but the muscles also had a high concentration of As than that of gills. The range of As detected in these tissues was in the following order: Liver (0.009-3.95?gg(-1))&gt;muscles (0.006-3.5?gg(-1))&gt;gills (0.002-2.96?gg(-1)). Furthermore, the R. rita showed the highest concentration of As (2.18?gg(-1)) followed by S. sarvari (1.98?gg(-1)). The median concentrations of As, in the liver and muscles were also above the FAO/WHO, EPA permissible limits. The LPO activity was significantly related to As, which showed a possibility of cell membrane damage in these species. The human health risk assessment revealed that higher than normal concentration of As in muscle was particularly hazardous for the younger population.",
Arsenic,1936059,"The conserved Mediator subunit MDT-15 is required for oxidative stress responses in Caenorhabditis elegans Abstract: Reactive oxygen species (ROS) play important signaling roles in metazoans, but also cause significant molecular damage. Animals tightly control ROS levels using sophisticated defense mechanisms, yet the transcriptional pathways that induce ROS defense remain incompletely understood. In the nematode Caenorhabditis elegans, the transcription factor SKN-1 is considered a master regulator for detoxification and oxidative stress responses. Here, we show that MDT-15, a subunit of the conserved Mediator complex, is also required for oxidative stress responses in nematodes. Specifically, mdt-15 is required to express SKN-1 targets upon chemical and genetic increase of SKN-1 activity. mdt-15 is also required to express genes in SKN-1-dependent and -independent fashions downstream of insulin/IGF-1 signaling and for the longevity of daf-2/insulin receptor mutants. At the molecular level, MDT-15 binds SKN-1 through a region distinct from the classical transcription factor binding KIX-domain. Moreover, mdt-15 is essential for the transcriptional response to and survival on the organic peroxide tert-butyl-hydroperoxide (tBOOH), a largely SKN-1-independent response. The MDT-15 interacting Nuclear Hormone Receptor, NHR-64, is specifically required for tBOOH but not arsenite resistance, but NHR-64 is dispensable for the transcriptional response to tBOOH. Hence NHR-64 and MDT-15's mode of action remain elusive. Lastly, the role of MDT-15 in oxidative stress defense is functionally separable from its function in fatty acid metabolism, as exogenous polyunsaturated fatty acid complementation rescues developmental, but not stress sensitivity phenotypes of mdt-15 worms. Our findings reveal novel conserved players in the oxidative stress response and suggest a broad cytoprotective role for MDT-15.",
Arsenic,1355009,"Caffeic acid phenethyl ester (CAPE) prevents transformation of human cells by arsenite (As) and suppresses growth of As-transformed cells Abstract: Recent evidence suggests that inflammatory cytokines and growth factors contribute to arsenite (As)-induced human carcinogenesis. We investigated the expression of inflammatory cytokine mRNAs during the transformation process induced by chronic As exposure in non-tumorigenic human osteogenic sarcoma (N-HOS) cells using gene arrays, and results were confirmed by RT-PCR and protein arrays. Caffeic acid phenethyl ester (CAPE), a naturally occurring immunomodulating agent, was used to evaluate the role of inflammatory factors in the process of As-mediated N-HOS cell transformation and in As-transformed HOS (AsT-HOS) cells. We found that an 8-week continuous exposure of N-HOS to 0.3 microM arsenite resulted in HOS cell transformation. That exposure also caused substantial decreases in inflammatory cytokine mRNAs, such as interleukin (IL) IL-1alpha, IL-2, IL-8, IL-18, MCP-1, TGF-beta2, and TNF-alpha, while it increased c-jun mRNA in a time-dependent manner. Co-incubation of N-HOS with As and CAPE (0.5-2.5 microM) prevented As-mediated declines in cytokine mRNAs in the co-treated cells, as well as their transformation to anchorage independence, while it caused decreases in c-jun mRNA. CAPE (up to 10 microM) had no effect on growth of N-HOS cells. However, CAPE (1-10 microM) treatment of AsT-HOS cells inhibited cell growth, induced cell cycle G2/M arrest, and triggered apoptosis, accompanied by changes in cytokine gene expression, as well as decreases in cyclin B1 and cdc2 abundance. Resveratrol (RV) and (-)(.) epigallocatechin gallate (EGCG), preventive agents present in grapes and green tea, respectively, induced similar changes in AsT-HOS cell growth but required much higher doses than CAPE to cause 50% growth arrest (&lt;2.5 microM CAPE versus 25 microM RV or 50 microM EGCG). Overall, our findings suggest that inflammatory cytokines play an important role in the suppressive effects of CAPE on As-induced cell transformation and in the selective cytotoxicity of CAPE to As-transformed HOS cells.",
Arsenic,1597447,Mechanisms of Metal Resistance and Homeostasis in Haloarchaea Abstract: ,
Arsenic,2279248,"A nanofiltration-coagulation integrated system for separation and stabilization of arsenic from groundwater Abstract: A membrane-integrated hybrid treatment system has been developed for continuous removal of arsenic from contaminated groundwater with simultaneous stabilization of arsenic rejects for safe disposal. Both trivalent and pentavalent arsenic could be removed by cross flow nanofiltration following a chemical pre-oxidation step for conversion of trivalent arsenic into pentavalent form. The very choice of the membrane module and its judicious integration with upstream oxidation and downstream stabilization resulted in continuous removal of more than 98% arsenic from water that contained around 190mgL(-1) of total suspended solid, 205mgL(-1) of total dissolved solid, 0.18mgL(-1) of arsenic and 4.8mgL(-1) of iron at a pH of 7.2. The used flat sheet cross flow membrane module yielded a high flux of 144-145Lm(-2)h(-1) at a transmembrane pressure of only 16kgf·cm(-2) without the need for frequent replacement of the membranes. Transmembrane pressure, cross flow rate through the membrane module and oxidant dose were found to have pronounced effects on arsenic rejection and pure water flux. For the first time, an effective scheme for protection of the total environment has been ensured in this context where arsenic separated with high degree of efficiency has been stabilized in a solid matrix of iron and calcium under response surface optimized conditions. The study culminated in a total and sustainable solution to the problem of arsenic contamination of groundwater by offering arsenic-free water at a reasonably low price of only1.41$·m(-3).",
Arsenic,1031613,"The effects of prolonged oral arsenate exposure on liver mitochondria of mice: morphometric and biochemical studies Abstract: HEEP COPYRIGHT: BIOL ABS. Exposure of mice to As in drinking water at concentrations of 0, 20, 40, or 85 ppm for 6 wk resulted in mild swelling of hepatocyte mitochondria, binucleate cells, and a slight but not statistically significant increase in the overall relative volume-density of the nuclear compartment, as determined by ultrastructural morphometry. Despite only slight changes in morphometric parameters, hepatocyte mitochondria in arsenate-treated mice showed a significant decrease in pyruvate/malate, but not succinate-mediated state 3 respiration and respiratory control ratios, and decreases in P ratios with both substrate types. Mitochondria from arsenate treated mice also showed a significant dose-related increase of up to 175% of control of the specific activity of monoamine oxidase, which was used as an outer membranal marker enzyme. Cytochrome oxidase and Mg2+-ATPase, which are localized on the inner mitochondrial membrane showed statistically nonsignificant increases in specific activity of up to 150 and 120% of control, respectively. Malate dehydrogenase, which was used as a marker for enzymatic activity in the mitochondrial matrix, showed no significant alteration in activity. Ultrastructural and biochemical data were related to liver concentrations of total As. Despite little quantitative physical alteration of the mitochondrial compartment, significant changes in various membrane-associated biochemical functions may occur in mouse liver mitochondria during prolonged arsenate exposure.",
Arsenic,1677537,"Plasma level of homocysteine associated with severe vertebral fracture in postmenopausal women Abstract: The aim of this cross-sectional cohort study was to clarify risk factors for severe vertebral fractures in postmenopausal Japanese women. Subjects were ambulatory volunteers age over 50 years who were recruited from a population of outpatients at a primary care institute. At registration, age, body mass index (BMI), bone mineral density (BMD), and present illness were investigated. Biochemical parameters including urinary levels of type I collagen cross-linked N-telopeptides (NTXs), and pentosidine and plasma levels of homocysteine were measured. Values were compared with different fracture grades (grade 0-3). A total of 1,475 postmenopausal women (66.6 ± 9.0 years) were included in the present study. Distributions of vertebral fracture grades were grade 1, 137 cases (9.3 %); grade 2, 124 cases (8.4 %); and grade 3, 162 cases (11.0 %). Age, BMI, BMD, NTX, pentosidine, and homocysteine were significantly associated with vertebral fracture in unadjusted analysis. In addition, a higher prevalence of hypertension was observed in patients with severe fracture. When comparing vertebral fracture grade 0 versus grade 2-3 by multiple regression analysis, pentosidine and homocysteine levels were a significant risk for moderate/severe vertebral fracture (odds ratio [OR] = 1.17, 95 % confidence interval [CI] 1.00-1.38, p = 0.049; OR = 1.22, 95 % CI 1.03-1.46, p = 0.013). Homocysteine levels were also a significant risk when comparing vertebral fracture grade 0 versus grade 3 (OR = 1.27, 95 % CI 1.04-1.58, p = 0.021). Plasma level of homocysteine was an independent risk for severe vertebral fractures.",
Arsenic,1025559,"Incorporation of an internal ribosome entry site-dependent mechanism in arsenic-induced GADD45 alpha expression Abstract: We have previously shown that trivalent arsenic (arsenite, As(3+)) is able to induce GADD45 alpha expression in human bronchial epithelial cells through activation of c-Jun NH(2)-terminal kinase and nucleolin-dependent mRNA stabilization. In the present report, we show that As(3+) is capable of inducing translation of the GADD45 alpha protein through a cap-independent, or rather, an internal ribosome entry site (IRES)-dependent mechanism. In growth-arrested cells, As(3+) elevated the GADD45 alpha protein level in a dose- and time-dependent manner which did not correlate with the GADD45 alpha mRNA expression. Pretreatment of the cells with rapamycin, an inhibitor for the cap-dependent translation machinery through the suppression of mTOR and p70S6 kinase, failed to affect the induction of the GADD45 alpha protein induced by As(3+). Sequence analysis revealed a potential IRES element in the 5'-untranslated region of the GADD45 alpha mRNA. This IRES element in the 5'-untranslated region of the GADD45 alpha mRNA is functional in mediating As(3+)-induced translation of the GADD45 alpha protein in a dicistronic reporter gene activity assay. Immunoprecipitation and proteomic studies suggest that As(3+) impairs the assembly of the cap-dependent initiating complex for general protein translation but increases the association of human elongation factor 2 and human heterogeneous nuclear ribonucleoprotin with this complex. Thus, these results suggest that in growth-arrested cells, As(3+) is still capable of inducing GADD45 alpha expression through an IRES-dependent translational regulation.",
Arsenic,627099,"Elevation of 8-hydroxydeoxyguanosine and cell proliferation via generation of oxidative stress by organic arsenicals contributes to their carcinogenicity in the rat liver and bladder Abstract: Monomethylarsonic acid (MMAV), dimethylarsinic acid (DMAV) and trimethylarsine oxide (TMAOV) are well-documented inorganic arsenic (iAs) methylated metabolites. In our previous studies, DMAV and TMAOV were shown to exert carcinogenicity in the rat bladder and liver, respectively. Furthermore, MMAV, DMAV and TMAOV exhibited promoting activity on rat hepatocarcinogenesis. To clarify mechanisms of arsenical carcinogenicity and compare biological responses in the liver and bladder, male F344 rats were sequentially treated for 5, 10, 15, 20 days with MMAV, DMAV and TMAOV in their drinking water at a dose of 0.02%. Significant increase of P450 total content and generation of hydroxyl radicals in the liver were observed from 10 and 15 days of treatment with arsenicals, respectively, with the highest levels induced by TMAOV. Similarly, elevation of 8-hydroxy-2?-deoxyguanosine (8-OHdG) formation was found in the DNAwith significant increase by TMAOV treatment in the liver at days 15 and 20, and DMAV in the bladder after 20 days treatment. In addition, cell proliferation and apoptosis indices were significantly increased by TMAOV in the liver and by DMAV in the bladder of rats. These events were accompanied by differential up-regulation of phase I and II metabolizing enzymes, cyclins D1 and E, PCNA, caspase 3 and FasL. The results indicate that early elevation of 8-OHdG and cell proliferation via generation of oxidative stress by TMAOV and DMAV contributes to their carcinogenicity in the rat liver and bladder.",
Arsenic,627055,"Dimethylarsenics reveal DNA damage induced by superoxide anion radicals Abstract: We previously reported that DNA single-strand breaks (ssb) induced by exposure to dimethylarsinic acid (DMAA) were enhanced by the presence of paraquat (PQ), a superoxide anion radical 0 -(2)-producing agent, in cultured human alveolar type II (L-132) cells in vitro. In the present study, we examined the effect of sequential exposure of the cells to PQ and then DMAA under conditions causing no ssb by each alone, and observed a remarkable occurrence of ssb. The result suggests that 0 -(2) caused DNA damage, which became detectable as ssb by the treatment using DMAA. The DNA damage induced by the exposure to PQ alone was different from that by DMAA; PQ-induced damage was fully repaired after 24 h, while DMAA-induced damage was repaired only partially, and aphidicolin, an inhibitor of repair-serving DNA polymerases alpha, delta and/or epsilon, inhibited only the latter repair but not the former. These findings indicate that the DMAA treatment may be an effective tool to reveal DNA damage induced by 0 -(2), which to date has not been sufficiently clarified.",
Arsenic,2088319,"Evaluation of chemical immobilization treatments for reducing arsenic transport in red mud Abstract: Red mud (RM) was produced during alumina production from bauxite known as the Bayer process. Arsenic was detected in the solid phase of RM (RMsf) which was disposed in the disposal area. This study investigates the effectiveness of using Zero-valent iron (ZVI), ferrihydrite, ferrous sulfate (FeSO4), waste acid (WA) or CO2 for immobilization of arsenic in the RMsf. To test the effect of the amendments on the arsenic leachability, the RMsf samples were amended with the iron-based materials or acidifiers at various w/w (weight/weight) ratios (1-10 %) for 30 days. The leachability of arsenic in the RMsf was evaluated by a 4-step water elusion process. After 30-day treatment of the RMsf, the leachability of As decreased from an initial (12.7 %) to (7.0 %) with a w/w ratio of 5 % ZVI (0 %) with 5 % FeSO4 center dot 7H(2)O, (3.4 %) with 5 % ferryhydrite, (2.0 %) with 6 % WA and (11.8 %) with 6 % CO2. FeSO4 center dot 7H(2)O and WA showed more effectively than other amendments for immobilizing arsenic. Arsenic fractionation with a sequential extraction procedure was used to evaluate the arsenic migration potential in the RMsf. FeSO4 and WA were effective in increasing the hydrous oxide combined arsenic in the RMsf. The leachable Cl- and SO4 (2-) in the RMsf increased from 2.9 to 14.1 mg/g and 19.9-44.4 mg/g with 6 % WA and 5 % FeSO4 center dot 7H(2)O added, respectively. The estimated cost of the FeSO4 and WA treatment was 0.47 and 0.49 USD per ton, respectively.",
Arsenic,1021543,"Toxicity of volatile methylated species of bismuth, arsenic, tin, and mercury in Mammalian cells in vitro Abstract: The biochemical transformation of mercury, tin, arsenic and bismuth through formation of volatile alkylated species performs a fundamental role in determining the environmental processing of these elements. While the toxicity of inorganic forms of most of these compounds are well documented (e.g., arsenic, mercury) and some of them are of relatively low toxicity (e.g., tin, bismuth), the more lipid-soluble organometals can be highly toxic. In the present study we investigated the cyto- and genotoxicity of five volatile metal(loid) compounds: trimethylbismuth, dimethylarsenic iodide, trimethylarsine, tetramethyltin, and dimethylmercury. As far as we know, this is the first study investigating the toxicity of volatile metal(loid) compounds in vitro. Our results showed that dimethylmercury was most toxic to all three used cell lines (CHO-9 cells, CaCo, Hep-G2) followed by dimethylarsenic iodide. Tetramethyltin was the least toxic compound; however, the toxicity was also dependend upon the cell type. Human colon cells (CaCo) were most susceptible to the toxicity of the volatile compounds compared to the other cell lines. We conclude from our study that volatile metal(loid) compounds can be toxic to mammalian cells already at very low concentrations but the toxicity depends upon the metal(loid) species and the exposed cell type.",
Arsenic,2279413,"Association between betel quid chewing and carotid intima-media thickness in rural Bangladesh Abstract: <strong>BACKGROUND:: </strong>Areca nut, more commonly known as betel nut, is the fourth most commonly used addictive substance in the world. Though recent evidence suggests it may play a role in the development of cardiovascular disease, no studies have investigated whether betel nut use is related to subclinical atherosclerosis.<br /><br /><strong>METHODS:: </strong>We evaluated the association between betel nut use and subclinical atherosclerosis in 1206 participants randomly sampled from the Health Effects of Arsenic Longitudinal Study (HEALS). Frequency and duration of betel nut use were assessed at baseline, and carotid IMT was measured on average 6.65 years after baseline.<br /><br /><strong>RESULTS:: </strong>A positive association was observed between duration and cumulative exposure (function of duration and frequency) of betel nut use and IMT, with above-median use for duration (7 or more years) and cumulative exposure (30 or more quid-years) corresponding to a 19.1 ?m [95% confidence interval (CI): 5.3-32.8; P ? 0.01] and 16.8 ?m (95% CI: 2.9-30.8; P &lt; 0.05) higher IMT in an adjusted model, respectively. This association was more pronounced in men [32.8 ?m (95% CI: 10.0-55.7) and 30.9 ?m (95% CI: 7.4-54.2)]. There was a synergy between cigarette smoking and above-median betel use such that the joint exposure was associated with a 42.4 ?m (95% CI: 21.6-63.2; P ? 0.01) difference in IMT.<br /><br /><strong>CONCLUSION:: </strong>Betel nut use at long duration or high cumulative exposure levels is associated with subclinical atherosclerosis as manifested through carotid IMT. This effect is especially pronounced among men and cigarette smokers.",
Arsenic,1362760,"Induction of the 72-kD heat shock protein in human skin melanoma and squamous cell carcinoma cell lines Abstract: Heat shock proteins (HSPs) or stress proteins comprise a characteristic group of proteins synthesized in cells exposed to heat or other environmental stimuli. Of the many HSPs, the 72-kD heat shock protein (HSP72) is the most stress-inducible one. In the present study, we examined the effects of heat, chemicals (azetidine and sodium arsenite), ultraviolet (UV) light, and gamma-ray irradiation on the induction of HSP72 in cultured human skin melanoma cell lines (P-39 and G-361), a human skin squamous cell carcinoma cell line (HSC-1), and an SV40-transformed human lung fibroblast cell line (WI38VA13) as a control. In these cell lines, heat treatment induced HSP72 more rapidly and intensely than did chemical exposure. Compared with the SCC cell line, the two melanoma cell lines produced less HSP72 with heat treatment. UVC irradiation (20 J/m2) induced HSP72 only in the WI38VA13 cells. After gamma-ray irradiation, no HSP72 induction was detected in any of the cell lines examined. These observations suggest that, in cultured cells, inducibility of HSP72 depends not only on the inducer but also on the origin of each cell line.",
Arsenic,1339272,"Application of receptor-specific risk distribution in the arsenic contaminated land management Abstract: Concerns over health risks and financial costs have caused difficulties in the management of arsenic contaminated land in Taiwan. Inflexible risk criteria and lack of economic support often result in failure of a brownfields regeneration project. To address the issue of flexible risk criteria, this study is aimed to develop maps with receptor-specific risk distribution to facilitate scenario analysis of contaminated land management. A contaminated site risk map model (ArcGIS for risk assessment and management, abbreviated as Arc-RAM) was constructed by combining the four major steps of risk assessment with Geographic Information Systems. Sampling of contaminated media, survey of exposure attributes, and modeling of multimedia transport were integrated to produce receptor group-specific maps that depicted the probabilistic spatial distribution of risks of various receptor groups. Flexible risk management schemes can then be developed and assessed. In this study, a risk management program that took into account the ratios of various land use types at specified risk levels was explored. A case study of arsenic contaminated land of 6.387km(2) has found that for a risk value between 1.00E-05 and 1.00E-06, the proposed flexible risk management of agricultural land achieves improved utilization of land. Using this method, the investigated case can reduce costs related to compensation for farmland totaling approximately NTD 5.94 million annually.",
Arsenic,2343492,"Monitoring Arsenic Contamination in Agricultural Soils with Reflectance Spectroscopy of Rice Plants Abstract: The objective of this study was to explore the feasibility and to investigate the mechanism for rapidly monitoring arsenic (As) contamination in agricultural soils with the reflectance spectra of rice plants. Several data pretreatment methods were applied to improve the prediction accuracy. The prediction of soil As contents was achieved by partial least-squares regression (PLSR) using laboratory and field spectra of rice plants, as well as linear regression employing normalized difference spectral index (NDSI) calculated from fild spectra. For laboratory spectra, the optimal PLSR model for predicting soil As contents was achieved using Savitzky-Golay smoothing (SG), first derivative and mean center (MC) (root-mean-square error of prediction (RMSEP) = 14.7 mg kg(-1); r = 0.64; residual predictive deviation (RPD) = 1.31). For field spectra, the optimal PLSR model was also achieved using SG, first derivative and MC (RMSEP = 13.7 mg kg(-1); r = 0.71; RPD = 1.43). In addition, the NDSI with 812 and 782 nm obtained a prediction accuracy with r = 0.68, RMSEP = 13.7 mg kg(-1), and RPD = 1.36. These results indicated that it was feasible to monitor the As contamination in agricultural soils using the reflectance spectra of rice plants. The prediction mechanism might be the relationship between the As contents in soils and the chlorophyll-a/-b contents and cell structure in leaves or canopies of rice plants.",
Arsenic,1579353,"Arsenite adsorption on cryogels embedded with iron-aluminium double hydrous oxides: Possible polishing step for smelting wastewater? Abstract: Arsenic is among the most toxic elements and it commonly exists in water as arsenite (As(III)) and arsenate (As(V)) ions. As(III) removal often requires a pre-oxidation or pH adjustment step and it is a challenge to adsorb As(III) at circumneutral pH. In this study, iron-aluminium double hydrous oxides were synthesized and incorporated into cryogels. The resulting composite cryogels were evaluated for As(III) adsorption. Initial experiments indicated that the adsorbent showed similar adsorption kinetics for both As(V) and As(III) ions. The adsorption of As(III) best fit the Langmuir isotherm and the maximum adsorption capacity was 24.6mg/g. Kinetic modeling indicated that the mechanism of adsorption was chemisorption, making the adsorbent-adsorbate interactions independent of charge and hence allowing the adsorbent to function equally efficient across pH 4-11. A Swedish smelting wastewater was used to evaluate the adsorption performance in continuous mode. The studies showed that the adsorbent was successful in reducing the arsenic concentrations below the European Union emission limit (0.15mg/l) in a smelting wastewater collected after two precipitation processes. The arsenic removal was obtained without requiring a pH adjustment or a pre-oxidation step, making it a potential choice as an adsorbent for As(III) removal from industrial wastewaters.",
Arsenic,2347652,"Co-exposure of arsenic and cadmium through drinking water and tobacco smoking: Risk assessment on kidney dysfunction Abstract: The combined exposure of arsenic (As) and cadmium (Cd) causes more pronounced renal toxicity. The study aimed to evaluate the level of As and Cd in biological samples (blood and urine) of adults males, age ranged (30-50 years) exposed referent (ER) and exposed kidney patients (EKP), consumed contaminated drinking water of lake and smoking local cigarettes manufactured by tobacco plants grown on agricultural soil, irrigated with contaminated lake water. For comparative purpose age matched nonexoposed referent (NR) and nonexposed kidney patient (NKP), consumed municipal treaded water and smoking branded cigarette were also selected. The As and Cd levels in drinking water, biological samples, tobacco of branded and nonbranded cigarettes were analyzed using electrothermal atomic absorption spectrometry. The As and Cd concentrations in lake water were higher than the permissible limit recommended by the World Health Organization for drinking water. The As and Cd levels in local cigarette tobacco were found to be 3- to 4-folds higher than branded cigarettes. The biochemical parameters especially urinary N-acetyl-?-glucosaminidase (NAG) of ER, EKP, ER, and EKP subjects were studied as a biomarkers of renal dysfunction. The NAG values were found to be higher in EKP as compared to NKP (p?&lt;?0.01). The linear regressions showed higher correlations between As and Cd concentrations in water versus blood and urine samples of EKP (r?=?0.71-0.78 and 0.68-0.72), as compared to NKP (p?&lt;?0.05).",
Arsenic,710859,"Arsenite induces oxidative injury in rat brain: synergistic effect of iron Abstract: Sodium arsenite (arsenite)-induced neurotoxicity and its interaction with ferrous citrate (iron) was investigated in rat brain. In vitro data showed that arsenite (1-10 micromol/L) concentration dependently increased lipid peroxidation and the potency of arsenite was less than that of iron. The oxidative activity of arsenite, sodium arsenate (arsenate), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were evaluated by inducing lipid peroxidation in cortical homogenates, and the potency for this effect was as follows: arsenite &gt; arsenate &gt; MMA and DMA. Several well-known antioxidants, including glutathione, melatonin, and beta-estradiol inhibited arsenite-induced lipid peroxidation in a concentration-dependent manner. Our in vivo study employed intranigral infusion of arsenite (5 nmol) in the substantia nigra (SN) of anesthetized rats. Four hours to 7 days after infusion, lipid peroxidation was elevated while glutathione was depleted in the infused SN. The dopamine content in the striatum ipsilateral to arsenite-infused SN was first elevated 24 h and then decreased 7 days after intranigral infusion of arsenite. Using pretreatment of l-buthionine-[S,R]-sulfoximine (l-BSO, i.c.v.) to reduce glutathione content in rat brain, arsenite-induced oxidative injury was augmented. Low doses of arsenite (1.5 nmol) and iron (3 nmol) alone induced minimal oxidative injury; however, co-infusion of arsenite and iron augmented neurotoxicity, including elevated lipid peroxidation and reduced striatal dopamine content. Moreover, expression of heme oxygenase-1, alpha-synuclein aggregation, and DNA fragmentation were significantly enhanced in SN co-infused with low doses of arsenite and iron. Taken together, our study demonstrates that arsenite was less potent than iron in inducing oxidative stress. Furthermore, concomitant arsenite and iron potentiated oxidative injury in the nigrostriatal dopaminergic system, indicating that interaction of metals plays a more clinically-relevant role in pathophysiology of central nervous system neurodegeneration.",
Arsenic,1597427,The role of arsenic in Chalcolithic copper artefacts insights from Vila Nova de Sao Pedro (Portugal) Abstract: ,
Arsenic,2149369,Study on Interaction among Cerium-Arsenic-Iron Abstract: ,
Arsenic,1579365,The roles of selenium in protecting plants against abiotic stresses Abstract: ,
Arsenic,502479,"Mercury impairment of mouse thymocyte survival in vitro: Involvement of cellular thiols Abstract: Heavy metals are well known to be able to induce immunotoxicity, but comparative metal studies related to apoptosis have not been conducted. In the present study, the effects of arsenic, cadmium, gold, lead, manganese, and mercury on thymocytes from BALB/c mice were analyzed. Thymic cells were cultured for 3-24 h in vitro in the absence or presence of metal, and markers of apoptosis or cell death, including annexin V binding, DNA loss/oligonucleosomal fragmentation, 7-amino-actinomycin D uptake (loss of impermeance), changes of the mitochondrial membrane potential (JC-1 fluorescence), and Western analysis of cellular thiols, were assayed. Mercury (Hg) was the only metal shown to be consistently toxic with the dose and times utilized. Cadmium (Cd) was the only other metal tested that also produced some significant level of DNA loss; however, the induction of apoptosis by Cd was not as consistent as that observed with Hg. When Hg was added with 2-mercaptoethanol (2-ME), Hg produced greater toxicity. Endogenous DNA synthesis by thymocytes was immediately inhibited by Hg and Hg + 2-ME. The Hg + 2-ME-induced apoptosis appeared to be associated with altered levels of cellular thiols, in that glutathione (GSH) depletion was significant in comparison to the non-metal control and Hg alone. The increased Hg-induced toxicity in the presence of 2-ME likely was due to the ability of 2-ME to enhance (10- to 20-fold) the cellular uptake of Hg. Western analysis with biotin maleimide demonstrated that Hg + 2-ME and to a lesser extent the positive control dexamethasone eliminated many reactive thiols; the major thiol-reactive protein still reactive with the maleimide probe had an approximate Molecular Mass of 45 kD. Surprisingly, Hg alone enhanced the expression of this thiol-expressing protein, which by Mass Spectrometry (MS)/MS analysis was shown to be beta-actin. Hg also produced the appearance of yet to be identified new proteins. Based on the results with Hg 2-ME, it is suggested that numerous protein thiols participate in maintenance of cell survival and their loss is associated with apoptosis. The increased expression of new thiol-reactive proteins or thiol-reactive proteins with altered electrophoretic profiles needs to be further investigated. However, the enhanced toxicity attributed to Hg + 2-ME suggests that increased intracellular oxidative stress, observed as increased depletion of GSH, is responsible for the accelerated cell death.",
Arsenic,2347790,"Toxic and Essential Elements in Different Types of Compost Samples Abstract: The aim of this study is the evaluation of toxic and essential elements levers in compost of main farming areas in Yunnan, China. The determination Of the nitric acid/hydrogen peroxide soluble contents of 18 micro - and macro-elements (As, Pb, Cd, Ni, Cr, Hg, Co, Mo, Se, Cu, Zn, Mn, B, P, K, Ca, Mg and Fe) in composts was developed by the microwave digestion, technique combined with inductively coupled plasma optical emission or mass spectrometry. This investigated was focused on different types of compost. All of the results were compared with Standards and guidelines for marketable composts Mean characteristics of Compost's proved to be in good agreement with the specification of the GB quality assurance for :compost except a small portion of arsenic content and cadmium in samples could be above the GB specification, as well as one sample of chromium and mercury content which may cause serious environmental impacts. The experimental study was conducted Using three GB standard reference materials. Additional validation data are provided bases on the analysis of 9 different types of samples by the proposed method and using comparative Methods Of official GB methods. The calculated accuracy and precision confirmed the good performance of the adopted procedures.",
Arsenic,2088362,Speciation of As(III) and As(V) in water and sediment using reverse-phase ion-pair high-performance liquid chromatography-neutron activation analysis (HPLC-NAA) Abstract: ,
Arsenic,1017287,"Incidence of cleft pathology in greater New Orleans before and after Hurricane Katrina Abstract: Background: Reports after the 2005 Hurricane Katrina have documented an increase in stress reactions and environmental teratogens (arsenic, mold, alcohol). Objective: To assess the incidence of cleft pathology before and after the hurricane, and the distribution of cleft cases by gender and race. Methods: Retrospective chart review of cleft lip with or without cleft palate (CL/P) and cleft palate (CP) cases registered with the Cleft and Craniofacial Team at Children's Hospital of New Orleans, the surgical center that treated cleft cases in Greater New Orleans between 2004 and 2007. Live birth data were obtained from the Louisiana State Center for Health Statistics. Results: The incidence of cleft cases, beginning 9 months after the hurricane (i.e., June 1, 2006) was significantly higher compared with the period before the hurricane (0.80 versus 1.42; p ?=? .008). Within racial group comparisons showed a higher incidence among African Americans versus whites (0.42 versus 1.22; p ?=? .01). The distribution of CL/P and CP cases by gender was significant (p ?=? .05). Conclusion: The increase in the incidence of cleft cases after the hurricane may be attributable to increased stress and teratogenic factors associated with the hurricane. The increase among African Americans may have been due to comparatively higher exposure to environmental risk factors. These findings warrant further investigation to replicate the results elsewhere in the Gulf to determine whether there is a causal relationship between environmental risk factors and increased cleft pathology.",
Arsenic,711020,"A prospective study of respiratory symptoms associated with chronic arsenic exposure in Bangladesh: Findings from the Health Effects of Arsenic Longitudinal Study (HEALS) Abstract: A prospective cohort study was conducted to evaluate the effect of arsenic (As) exposure from drinking water on respiratory symptoms using data from the Health Effects of Arsenic Exposure Longitudinal Study (HEALS), a large prospective cohort study established in Ariahazar, Bangladesh in 2000-2002. A total of 7.31, 9.95 and 2.03% of the 11 746 participants completing 4 years of active follow-up reported having a chronic cough, breathing problem or blood in their sputum, respectively, as assessed by trained physicians.<br /><br /> Cox regression models were used to estimate HRs for respiratory symptoms during the follow-up period in relation to levels of chronic As exposure assessed at baseline, adjusting for age, gender, smoking, body mass index, education and arsenic-related skin lesion status.<br /><br /> Significant positive associations were found between As exposure and respiratory symptoms. As compared with those with the lowest quintile of water As level (<or=7 microg/l), the HRs for having respiratory symptoms were 1.27 (95% CI 1.09 to 1.48), 1.39 (95% CI 1.19 to 1.63), 1.43 (95% CI 1.23 to 1.68) and 1.43 (95% CI 1.22 to 1.68) for the second to fifth quintiles of baseline water As concentrations (7-40, 40-90, 90-178 and >178 microg/l), respectively. Similarly, the corresponding HRs in relation to the second to fifth quintiles of urinary arsenic were 1.10 (95% CI 0.94 to 1.27), 1.11 (95% CI 0.95 to 1.29), 1.29 (95% CI 1.11 to 1.49) and 1.35 (95% CI 1.16 to 1.56), respectively. These associations did not differ appreciably by cigarette smoking status.<br /><br /> This prospective cohort study found a dose-response relationship between As exposure and clinical symptoms of respiratory diseases in Bangladesh. In particular, these adverse respiratory effects of As were clearly evident in the low to moderate dose range, suggesting that a large proportion of the country's population may be at risk of developing serious lung diseases in the future.",
Arsenic,1030940,"Arsenic poisoning Abstract: Arsenic poisoning continues to require awareness of its diverse clinical manifestations. Industry is the major source of arsenic exposure. Although epidemiologic studies strongly contend that arsenic is carcinogenic, there are little supportive research data. Arsenic poisoning, both acute and chronic, is often overlooked initially in the evaluation of the patient with multisystem disease, but once it is suspected, many accurate methods are available to quantitate the amount and duration of exposure. Treatment with dimercaprol remains the mainstay of therapy, and early treatment is necessary to prevent irreversible complications.",
Arsenic,1015878,"Silibinin potentially protects arsenic-induced oxidative hepatic dysfunction in rats Abstract: Arsenic (As) compounds are reported as environmental toxicants and human carcinogens. Exposure to arsenic imposes a big health issue worldwide. Silibinin (SB) is a major flavonolignan compound of silimarin and is found in milk thistle of Silybum marianum. It has been reported that silibinin has antioxidant efficacy as metal chelators due to the orientation of its functional groups. However, it has not yet been explored in experimental animals. In view of this fact, the purpose of this study was to delineate the ameliorative role of silibinin against arsenic-induced hepatotoxicity in rats. Rats were orally treated with arsenic alone (5?mg/kg body weight (bw)/day) plus silibinin (75?mg/kg bw/day) for 4weeks. Hepatotoxicity was evaluated by the increased activities of serum hepatospecific enzymes namely aspartate transaminase, alanine transaminase, alkaline phosphatase, gamma glutamyl transferase, lactate dehydrogenase and total bilirubin along with increased elevation of lipid peroxidative markers, thiobarbituric acid reactive substances, lipid hydroperoxides, protein carbonyl content and conjugated dienes. The toxic effect of arsenic was also indicated by significantly decreased activities of membrane bound ATPases, enzymatic antioxidants like superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase and glucose-6-phosphate dehydrogenase along with nonenzymatic antioxidants like reduced glutathione, total sulfhydryl groups, vitamins C and E. Administration of silibinin exhibited a significant reversal of arsenic-induced toxicity in hepatic tissue. All these changes were supported by reduction of DNA damage in hepatocytes and histopathological observations of the liver. These results suggest that silibinin has a potential protective effect over arsenic-induced hepatotoxicity in rat.",
Arsenic,134649,"Dose-dependent effects on tissue distribution and metabolism of dimethylarsinic acid in the mouse after intravenous administration Abstract: Most mammals methylate inorganic arsenic to dimethylarsinic acid (DMA). This organic arsenical causes organ-specific toxicity and is a multi-organ tumor promoter. The objective of this study was to examine whether dose could affect the distribution and metabolism of DMA. Female B6C3F1 mice (3–4/time point) were administered 1.11 or 111 mg/kg of DMA (1 ?Ci of [14C] or unlabeled) intravenously and killed serially (5–480 min). Blood was separated into plasma and red blood cell fractions and liver, kidney and lung were removed, weighed and homogenized. Tissue samples were oxidized and analyzed for DMA-derived radioactivity. Blood and several organs of the non-radioactive DMA-treated animals were digested in acid and analyzed by hydride generation atomic absorption spectrophotometry for DMA and metabolites. Concentration–time profiles showed a biexponential decrease of DMA-derived radioactivity in all tissues examined. Kidney had the highest concentration (1–20% dose/gm) of radioactivity of all tissues up to 60 min post-administration. Concentration of radioactivity was greater in plasma than red blood cells at 5 and 15 min and then was similar for the remaining time points. A dose-dependent effect on the concentration of radioactivity was observed in the lung. The retention of radioactivity in the lung was altered compared with liver and kidney, with a much longer t 1/2? and a disproportionate increase in area under the curve with increased dose. No methylated or demethylated products of DMA were detected in blood or any organ up to 8 h post-exposure. The dose-dependent distribution of DMA in the lung may have a role in the toxic effects DMA elicits in this organ",
Arsenic,1240223,"Arsenic affects essential and non-essential amino acids differentially in rice grains: Inadequacy of amino acids in rice based diet Abstract: Recent breakthroughs in rice arsenic (As) research demonstrate that As accumulation significantly affects trace nutrients in rice grain. In the present study we analyzed the amino acid (AA) profile of sixteen rice genotypes differing in grain As accumulation, grown at three sites with different soil As concentrations, in ascending order, Chinsurah&lt;Purbosthali&lt;Birnagar. Grain As accumulation negatively correlated with essential amino acids (EAAs) which were more prominent in high As accumulating rice genotypes (HAARGs). Conversely, non-essential amino acids (NEAAs) showed an increase in low As accumulating rice genotypes (LAARGs) but a decrease in HAARGs. EAAs like isoleucine, leucine, valine, phenylalanine, and tyrosine also decreased in most of the genotypes. NEAAs like glutamic acid, glycine, proline, and histidine showed an increase in all LAARGs. Likewise, sulfur containing AAs (methionine and cysteine) increased in LAARGs but decreased in HAARGs. Among NEAAs in HAARGs, only arginine and serine showed some induction in most of the genotypes. At the highest As site (Birnagar) total EAAs and NEAAs show significant reduction in HAARGs compared to LAARGs. The study concluded that As accumulation in rice grain alters EAAs and NEAAs differentially, and reduction was more pronounced in HAARGs than in LAARGs. Thus, As tainted rice limits required levels of AAs in rice based diets and therefore cannot alone fulfill the recommended daily intake (RDI) of AAs.",
Arsenic,1022142,"Total and inorganic arsenic concentrations in different species of economically important algae harvested from coastal zones of Chile Abstract: Chile is one of the major producers of phytocolloids extracted from seaweed. Multicellular algae are considered to be primary accumulators of arsenic. We analyzed 14 species of algae belonging to the groups Rhodophyceae (10), Phaeophyceae (3) and Chlorophyceae (1) from different coastal zones of Chile in 2003-2004. Dry ashing mineralization (for total As) and acid digestion (for inorganic As) together with quantification by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) were employed. In general, total arsenic concentrations varied between 3.0 and 68mgkg(-1), whereas inorganic arsenic concentrations ranged between 0.15 and 1.06mgkg(-1). The algal species Durvillaea antarctica and Porphyra columbina, used for direct human consumption, did not have inorganic arsenic levels that represent a health risk to consumers. Among species used for phytocolloids production, such as Macrocystis piryfera, Gracilaria chilensis and Gigartina skottsbergii, observed levels of inorganic arsenic were greater than 1mgkg(-1), the limit value established by the regulations of some countries. Among the 14 species of algae tested, inorganic arsenic levels were between 0.8% and 13% of the total arsenic concentrations; that is, arsenic present in these algae was found primarily as organic arsenic.",
Arsenic,502150,"Combined administration of iron and monoisoamyl-DMSA in the treatment of chronic arsenic intoxication in mice Abstract: Co-administration of iron in combination with monoisoamyl dimercaptosuccinic acid (MiADMSA) against chronic arsenic poisoning in mice was studied. Mice preexposed to arsenic (25 ppm in drinking water for 6 months) mice were treated with MiADMSA (50 mg/kg, intraperitoneally) either alone or in combination with iron (75 or 150 mg/kg, orally) once daily for 5 days. Arsenic exposure led to a significant depletion of blood delta-aminolevulinic acid dehydratase (ALAD) activity, hematocrit, and white blood cell (WBC) counts accompanied by small decline in blood hemoglobin level. Hepatic reduced glutathione (GSH) level, catalase and superoxide dismutase (SOD) activities showed a significant decrease while, oxidized glutathione (GSSG) and thiobarbituric acid-reactive substances (TBARS) levels increased on arsenic exposure, indicating arsenic-induced hepatic oxidative stress. Liver aspartate and alanine transaminases (AST and ALT) activities also decreased significantly on arsenic exposure. Kidney GSH, GSSG, catalase level and SOD activities remained unchanged, while, TBARS level increased significantly following arsenic exposure. Brain GSH, glutathione peroxidase (GPx), and SOD activities decreased, accompanied by a significant elevation of TBARS level after chronic arsenic exposure. Treatment with MiADMSA was marginally effective in reducing ALAD activity, while administration of iron was ineffective when given alone. Iron when co-administered with MiADMSA restored blood ALAD activity. Administration of iron alone had no beneficial effects on hepatic oxidative stress, while in combination with MiADMSA it produced significant decline in hepatic TBARS level compared to the individual effect of MiADMSA. Renal biochemical variables were insensitive to any of the treatments. Combined administration of iron with MiADMSA also had no additional beneficial effect over the individual protective effect of MiADMSA on brain oxidative stress. Interestingly, combined administration of iron with MiADMSA provided more pronounced depletion of blood arsenic, while no additional beneficial effects on tissue arsenic level over the individual effect of MiADMSA were noted. The results lead us to conclude that iron supplementation during chelation has some beneficial effects particularly on heme synthesis pathway and blood arsenic concentration.",
Arsenic,2347701,"Prognosis for patients with CML and &gt;10% BCR-ABL1 after 3 months of imatinib depends on the rate of BCR-ABL1 decline Abstract: In chronic myeloid leukemia (CML) patients, a breakpoint cluster region-Abelson (BCR-ABL1) value &gt;10% at 3 months of therapy is statistically associated with poorer outcome, yet many of these patients still achieve satisfactory outcomes. We investigated 528 first-line imatinib-treated patients to determine whether patients with the poorest outcome can be better discriminated at 3 months. All outcomes were significantly superior for the 410 patients with BCR-ABL1 ?10% at 3 months (P &lt; .001). However, the poorest outcomes among the 95 evaluable patients with BCR-ABL1 &gt;10% at 3 months were identified by the rate of BCR-ABL1 decline from baseline, assessed by estimating the number of days over which BCR-ABL1 halved. Patients with BCR-ABL1 halving time &lt;76 days (n = 74) had significantly superior outcomes compared with patients whose BCR-ABL1 values did not halve by 76 days (n = 21; 4-year overall survival, 95% vs 58%, P = .0002; progression-free survival, 92% vs 63%, P = .008; failure-free survival, 59% vs 6%, P &lt; .0001; and major molecular response, 54% vs 5%, P = .008). By multivariate analysis, the halving time was an independent predictor of outcome in this poor risk group. Our study highlighted that the rate of BCR-ABL1 decline may be a critical prognostic discriminator of the patients with very poor outcome among those &gt;10% at 3 months. The International Randomized IFN vs STI571 (IRIS) trial was registered at http://www.clinicaltrials.gov as #NCT00006343. The Tyrosine Kinase Inhibitor Optimization and Selectivity (TOPS) trial was registered at http://www.clinicaltrials.gov as #NCT00124748. The Therapeutic Intensification in DE-novo Leukaemia (TIDEL) I trial was registered at http://www.ANZCTR.org.au as #ACTRN12607000614493. The TIDEL II trial was registered at http://www.ANZCTR.org.au as #ACTRN12607000325404.",
Arsenic,1351930,"P38 MAPK activation selectively induces cell death in K-ras-mutated human colon cancer cells through regulation of vitamin D receptor Abstract: Ras is the most characterized oncogene in human cancer, and yet there are no effective therapeutics to selectively target this oncogene. Our previous work demonstrated the inhibitory activity of the p38 pathway in Ras proliferative signaling in experimental NIH 3T3 cells (Chen, G., Hitomi, M., Han, J., and Stacey, D. W. (2000) J. Biol. Chem. 275, 38973-38980). Here we explore the therapeutic potential of p38 kinase activation in human colon cancer cells with and without endogenous K-ras activation. p38 activation by both adenovirus-mediated gene delivery of constitutively active p38 activator MKK6 and by arsenite selectively induces cell death in K-ras-activated human colon cancer HCT116 cells but not in the K-ras-disrupted HCT116-derived sublines. The cell death-inducing effect of MKK6 is not because of its selective activation of p38 kinase or its downstream transcription factor substrates, ATF-2 or c-Jun, in K-ras-activated cells. Rather, cell death in K-ras-activated cells is linked to the down-regulation of vitamin D receptor (VDR) by an AP-1-dependent mechanism. Forced VDR expression in K-ras-activated cells inhibits p38 activation-induced cell death, and inhibition of endogenous VDR protein expression in K-ras-disrupted cells increased the arsenite-induced toxicity. Analysis of an additional two human colon cancer cell lines with and without K-ras mutation also showed a K-ras- and VDR-dependent toxicity of MKK6. Hence, p38 pathway activation selectively induces cell death in K-ras-mutated human colon cancer cells by mechanisms involving the suppression of VDR activity.",
Arsenic,1017178,"Trivalent arsenicals and glucose use different translocation pathways in mammalian GLUT1 Abstract: Rat glucose transporter isoform 1 or rGLUT1, which is expressed in neonatal heart and the epithelial cells that form the blood-brain barrier, facilitates uptake of the trivalent arsenicals arsenite as As(OH)? and methylarsenite as CH?As(OH)?. GLUT1 may be the major pathway for arsenic uptake into heart and brain, where the metalloid causes cardiotoxicity and neurotoxicity. In this paper, we compare the translocation properties of GLUT1 for trivalent methylarsenite and glucose. Substitution of Ser(66), Arg(126) and Thr(310), residues critical for glucose uptake, led to decreased uptake of glucose but increased uptake of CH?As(OH)?. The K(m) for uptake of CH?As(OH)? of three identified mutants, S66F, R126K and T310I, were decreased 4-10 fold compared to native GLUT1. The osmotic water permeability coefficient (P(f)) of GLUT1 and the three clinical isolates increased in parallel with the rate of CH?As(OH)? uptake. GLUT1 inhibitors Hg(II), cytochalasin B and forskolin reduced uptake of glucose but not CH?As(OH)?. These results indicate that CH?As(OH)? and water use a common translocation pathway in GLUT1 that is different to that of glucose transport.",
Arsenic,1015787,"Differential response of oxidative stress and thiol metabolism in contrasting rice genotypes for arsenic tolerance Abstract: The mechanism of arsenic (As) tolerance was investigated on two contrasting rice (Oryza sativa L.) genotypes, selected for As tolerance and accumulation. One tolerant (Triguna) and one sensitive (IET-4786) variety were exposed to various arsenate (0-50?M) levels for 7d for biochemical analyses. Arsenic induced oxidative stress was more pronounced in IET-4786 than Triguna especially in terms of reactive oxygen species, lipid peroxidation, EC and pro-oxidant enzymes (NADPH oxidase and ascorbate oxidase). However, Triguna tolerated As stress through the enhanced enzymes activities particularly pertaining to thiol metabolism such as serine acetyl transferase (SAT), cysteine synthase (CS), ?-glutamyl cysteine synthase (?-ECS), ?-glutamyl transpeptidase (?-GT), and glutathione-S-transferase (GST) as well as arsenate reductase (AR). Besides maintaining the ratio of redox couples GSH/GSSG and ASC/DHA, the level of phytochelatins (PCs) and phytochelatin synthase (PCS) activity were more pronounced in Triguna, in which harmonized responses of thiol metabolism was responsible for As tolerance in contrast to IET-4786 showing its susceptible nature towards As exposure.",
Arsenic,2278828,"A low-dose arsenic-induced p53 protein-mediated metabolic mechanism of radiotherapy protection Abstract: Radiotherapy is the current frontline cancer treatment, but the resulting severe side effects often pose a significant threat to cancer patients, raising a pressing need for the development of effective strategies for radiotherapy protection. We exploited the distinct metabolic characteristics between normal and malignant cells for a metabolic mechanism of normal tissue protection. We showed that low doses of arsenic induce HIF-1?, which activates a metabolic shift from oxidative phosphorylation to glycolysis, resulting in increased cellular resistance to radiation. Of importance is that low-dose arsenic-induced HIF-1? requires functional p53, limiting the glycolytic shift to normal cells. Using tumor-bearing mice, we provide proof of principle for selective normal tissue protection against radiation injury.",
Arsenic,1330196,"ARS2 is a conserved eukaryotic gene essential for early mammalian development Abstract: Determining the functions of novel genes implicated in cell survival is directly relevant to our understanding of mammalian development and carcinogenesis. ARS2 is an evolutionarily conserved gene that confers arsenite resistance on arsenite-sensitive Chinese hamster ovary cells. Little is known regarding the function of ARS2 in mammals. We report that ARS2 is transcribed throughout embryonic development and is expressed ubiquitously in mouse and human tissues. The mouse ARS2 protein is predominantly localized to the nucleus, and this nuclear localization is ablated in ARS2-null embryos, which in turn die around the time of implantation. After 24 h of culture, ARS2-null blastocysts contained a significantly greater number of apoptotic cells than wild-type or heterozygous blastocysts. By 48 h of in vitro culture, null blastocysts invariably collapsed and failed to proliferate. These data indicate ARS2 is essential for early mammalian development and is likely involved in an essential cellular process. The analysis of data from several independent protein-protein interaction studies in mammals, combined with functional studies of its Arabidopsis ortholog, SERRATE, suggests that this essential process is related to RNA metabolism.",
Arsenic,1575004,"EVALUATION OF PROCESSES CONTROLLING THE ENRICHMENT OF ARSENIC IN GROUNDWATER FROM THE DATONG BASIN, NORTHERN CHINA Abstract: ",
Arsenic,710904,"Distribution of speciated arsenicals in mice exposed to arsenite at the early life Abstract: The aim of this study was to explore distribution of speciated arsenicals in mice exposed to arsenite at early developmental stages. Levels of speciated arsenicals in both liver and brain of mice were analyzed by hydride generation of volatile arsines, and determined by atomic absorption spectrophotometry (HG-AAS). In the liver, levels of inorganic arsenic (iAs) increased on postnatal day (PND) 15, and monomethylarsonic acid (MMA) increased on PND 21, however, levels of dimethylarsinic acid (DMA) in newborn mice were significantly higher than those on PND 10 and 15. In the brain, levels of iAs on PND 21 were the highest; iAs levels on PND 15 were also significantly higher than those on PND 35. Our results suggested transplacental transfer of arsenicals from pregnant mice into their fetus was relatively efficient, lactational transfer from mother mice into their offspring was inefficient, and transfer of iAs from blood into brain at early developmental stages was efficient.",
Arsenic,1579394,"Differential toxicity and accumulation of inorganic and methylated arsenic in rice Abstract: Background and aims: Efficient accumulation of arsenic (As) in rice (Oryza sativa L.) poses a potential health risk to rice consumers. The aim of this study was to investigate the mechanisms of uptake, transport and distribution of inorganic arsenic (Asi) and dimethylarsinic acid (DMA) in rice plants. Methods: Rice was exposed to Asi (As(V)) and DMA in hydroponics. High-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and synchrotron X-ray fluorescence (SXRF) microprobe were used to determine As concentration and the in situ As distribution. Results: DMA induced abnormal florets before flowering and caused a sharp decline in the seed setting rate after flowering compared to Asi. Rice grains accumulated 2-fold higher DMA than Asi. The distribution of Asi concentration (root > leaf > husk > caryopsis) in As(V) treatments was different from that of the DMA concentration (caryopsis > husk > root ? leaf) in DMA treatments. SXRF showed that Asi mainly accumulated in the vascular trace of caryopsis with limited distribution to the endosperm, whereas DMA was observed in both tissues. Conclusions: DMA tended to accumulate in caryopsis and induced higher toxicity to the reproductive tissues resulting in markedly reduced grain yield, whereas Asi mainly remained in the vegetative tissues and had no significant effect on yield. DMA is more toxic than Asi to the reproductive tissues when both of them are at similar concentrations in nutrient solution.",
Arsenic,1028753,"Early-life nutritional and environmental determinants of thymic size in infants born in rural Bangladesh Abstract: <strong>AIM: </strong>The aim was to assess the impact of nutritional status and environmental exposures on infant thymic development in the rural Matlab region of Bangladesh.<br /><br /><strong>METHODS: </strong>In a cohort of N(max) 2094 infants born during a randomized study of combined interventions to improve maternal and infant health, thymic volume (thymic index, TI) was assessed by ultrasonography at birth and at 8, 24 and 52 weeks of age. Data on birth weight, infant anthropometry and feeding status were also collected.<br /><br /><strong>RESULTS: </strong>At all ages, TI was positively associated with infant weight and strongly associated with the month of measurement. Longer duration of exclusive breastfeeding resulted in a larger TI at 52 weeks. TI at birth and at 8 weeks correlated positively with birth weight, but by 24 and 52 weeks and when adjusted for infant weight this effect was no longer present. Thymic size was not affected by pre-natal maternal supplementation or by socioeconomic status but was correlated to arsenic exposure during pregnancy.<br /><br /><strong>CONCLUSION: </strong>In this population of rural Bangladeshi infants, thymic development is influenced by both nutritional and environmental exposures early in life. The long-term functional implications of these findings warrant further investigation.",
Arsenic,2064301,"Spatial distribution and source apportionment of water pollution in different administrative zones of Wen-Rui-Tang (WRT) river watershed, China Abstract: Water quality degradation in river systems has caused great concerns all over the world. Identifying the spatial distribution and sources of water pollutants is the very first step for efficient water quality management. A set of water samples collected bimonthly at 12 monitoring sites in 2009 and 2010 were analyzed to determine the spatial distribution of critical parameters and to apportion the sources of pollutants in Wen-Rui-Tang (WRT) river watershed, near the East China Sea. The 12 monitoring sites were divided into three administrative zones of urban, suburban, and rural zones considering differences in land use and population density. Multivariate statistical methods [one-way analysis of variance, principal component analysis (PCA), and absolute principal component score-multiple linear regression (APCS-MLR) methods] were used to investigate the spatial distribution of water quality and to apportion the pollution sources. Results showed that most water quality parameters had no significant difference between the urban and suburban zones, whereas these two zones showed worse water quality than the rural zone. Based on PCA and APCS-MLR analysis, urban domestic sewage and commercial/service pollution, suburban domestic sewage along with fluorine point source pollution, and agricultural nonpoint source pollution with rural domestic sewage pollution were identified to the main pollution sources in urban, suburban, and rural zones, respectively. Understanding the water pollution characteristics of different administrative zones could put insights into effective water management policy-making especially in the area across various administrative zones.",
Arsenic,2279544,"Impact of caste on the neurodevelopment of young children from birth to 36 months of age: a birth cohort study in Chitwan Valley, Nepal Abstract: <strong>BACKGROUND: </strong>Caste, a proxy of socioeconomic position, can influence the neurodevelopment of children through several pathways, including exposure to toxic elements. Studies from developing countries where caste is represented by prevailing caste groups and people are highly exposed to toxic elements can provide useful insights into the mechanisms of neurodevelopmental inequities among children. This study aims to investigate the impact of caste on the neurodevelopment of children from birth to 36 months of age in Chitwan Valley, Nepal, where people are exposed to high levels of arsenic (As) and lead (Pb).<br /><br /><strong>METHODS: </strong>Participants (N?=?94) were mother-infant pairs from the Chitwan district in Nepal. The neurodevelopment of the infants was assessed using the Brazelton Neonatal Behavioral Assessment Scale, Third Edition, (NBAS III) at birth and the Bayley Scales of Infant Development, Second Edition, (BSID II) at ages 6, 24, and 36 months. Caste was categorized based on surname, which, in Nepal generally refers to one of four caste groups. We also measured the concentrations of As and Pb in cord blood.<br /><br /><strong>RESULTS: </strong>Caste was positively associated with the state regulation cluster score of the NBAS III at birth after adjustment for covariates (p for trend &lt; 0.01). Adding cord blood As levels attenuated the association (p for trend = 0.12). With regard to neurodevelopment at six months of age, the third-ranked caste group scored higher than the first-ranked caste group on the Mental Development Index (MDI) of the BSID II (coefficient = 3.7; 95% confidence interval (CI) = 1.3 to 6.0). This difference remained significant after adjustment for cord blood As levels and other covariates was made (coefficient = 3.9; 95% CI = 1.2 to 6.7). The remaining clusters of the NBAS III and BSID II at 6, 24, and 36 months were not significantly associated with caste group.<br /><br /><strong>CONCLUSIONS: </strong>Caste was positively associated with the state regulation cluster score of NBAS III at birth. This association was partially mediated by cord blood As levels. However, the negative impact of caste on neurodevelopment disappeared as the children grew. Furthermore, an inverse association between caste and MDI at six months of age was observed. Additional studies are needed to elucidate the mechanism of how caste affects neurodevelopment.",
Arsenic,710986,"Maternal exposure to low-level heavy metals during pregnancy and birth size Abstract: We evaluated the effect of environmental, low-level exposure to heavy metals during pregnancy, as estimated by urine analysis, on birth size of the newborns. Spot urine samples were collected from unexposed 78 pregnant women in Tokyo during 2007 and 2008. The urinary concentrations of beryllium (Be), copper (Cu), arsenic (As), zinc (Zn), selenium (Se), molybdenum (Mo), cadmium (Cd), tin (Sn), antimony (Sb), and lead (Pb) were measured by ICP-MS. The birthweight (BW), length (BL) and head circumference (HC) of the newborns delivered to the subjects were measured and relationship with urinary metal concentration was examined. The geometric mean concentration of urinary Be, Cu, As, Zn, Se, Mo, Cd, Sn, Sb, and Pb were 0.031, 12.8, 393, 76.9, 37.6, 79.0, 0.766, 0.232, &lt; 0.21, 0.483 microg g-creatinine(-1), respectively. The mean birth size of the newborn was close to the national average value in Japan. Stepwise multiple regression analysis using birth size as a dependent variable and urinary metal concentrations and covariates as independent variables extracted urinary Cd with a significant negative standardized partial regression coefficient (beta) for BW along with gestational age and maternal BMI. For HC, Sn was selected with a negative beta. The present study suggested that even a low-level Cd body burden of general population has slight but significant negative effect on BW.",
Arsenic,2278532,"Relationship between firewood usage and urinary Cr, Cu and As in informal areas of Cape Town Abstract: Objectives. The study investigated whether wood usage by informal food vendors and household residents in Cape Town results in the absorption of arsenic (As), chromium (Cr) and copper (Cu) owing to release of these metals in the burning of chromated copper arsenate (CCA)-treated wood. Methods. The participants (N=78) selected included an equal number of food vendors and non-vendors from 2 informal settlements. All participants answered a questionnaire concerning exposure and were tested for urinary Cr, Cu and As, while the urine of 29 participants was also tested for toxic As (As(tox)). Results. Multivariate analysis showed that the time spent in close proximity to the wood, as well as the quantity of wood used for cooking and for household use, was weakly positively associated with urinary levels of As, Cr and the sum of As, Cr and Cu. Conclusions. The study provides evidence that use of wood likely to contain CCA as a fuel for informal food outlets and household purposes may increase the absorption of inorganic As, Cu and Cr.",
Arsenic,1016849,"Mental health burden amongst inhabitants of an arsenic-affected area in Inner Mongolia, China Abstract: Inner Mongolia, China, is an area with high levels of arsenic. The adverse health effects resulting from chronic arsenic exposure include skin keratosis, vascular diseases and cancers. However, the effects of arsenic exposure on mental health have not received much attention. The purpose of this study was to examine the effects of arsenic poisoning on the mental health of the inhabitants of an arsenic-affected area. We performed a cross-sectional study at two villages in Hetao Plain, Inner Mongolia. The populations of both villages were similar in age, sex, lifestyle, socioeconomic conditions, and geographic location. One hundred and thirty four (93.7%) of the 143 inhabitants in the arsenic-affected village and 36 (76.6%) of the 47 inhabitants in the arsenic-free village participated in the study. Subjects with a 30-item version of General Health Questionnaire score of 9 or more were defined as having symptoms of distress. The multiple logistic analyses showed that the mental health of the subjects in the arsenic-affected village was worse than in those in the arsenic-free village (OR=2.5, 95% CI=1.1-6.0). The effect of arsenic on mental health in arsenic-affected areas deserves further investigation. The mental health burden in arsenic-affected areas should be considered in the wider context of public and community health.",
Arsenic,1251028,"Indigenous soil bacteria with the combined potential for hydrocarbon consumption and heavy metal resistance Abstract: <strong>INTRODUCTION: </strong>Transconjugant bacteria with combined potential for hydrocarbon utilization and heavy metal resistance were suggested by earlier investigators for bioremediation of soils co-contaminated with hydrocarbons and heavy metals. The purpose of this study was to offer evidence that such microorganisms are already part of the indigenous soil microflora.<br /><br /><strong>METHODS: </strong>Microorganisms in pristine and oily soils were counted on nutrient agar and a mineral medium with oil as a sole carbon source, in the absence and presence of either sodium arsenate (As V), sodium arsenite (As III) or cadmium sulfate, and characterized via 16S rRNA gene sequencing. The hydrocarbon-consumption potential of individual strains in the presence and absence of heavy metal salts was measured.<br /><br /><strong>RESULTS: </strong>Pristine and oil-contaminated soil samples harbored indigenous bacteria with the combined potential for hydrocarbon utilization and As and Cd resistance in numbers up to 4?×?10? CFU g?¹. Unicellular bacteria were affiliated to the following species arranged in decreasing order of predominance: Bacillus subtilis, Corynebacterium pseudotuberculosis, Brevibacterium linens, Alcaligenes faecalis, Enterobacter aerogenes, and Chromobacterium orangum. Filamentous forms were affiliated to Nocardia corallina, Streptomyces flavovirens, Micromonospora chalcea, and Nocardia paraffinea. All these isolates could grow on a wide range of pure aliphatic and aromatic hydrocarbons, as sole sources of carbon and energy, and could consume oil and pure hydrocarbons in batch cultures. Low As concentrations, and to a lesser extent Cd concentrations, enhanced the hydrocarbon-consumption potential by the individual isolates.<br /><br /><strong>CONCLUSION: </strong>There is no need for molecularly designing microorganisms with the combined potential for hydrocarbon utilization and heavy metal resistance, because they are already a part of the indigenous soil microflora.",
Arsenic,2343512,"HIV viremia and incidence of non-Hodgkin lymphoma in patients successfully treated with antiretroviral therapy Abstract: Background.?The incidence of non-Hodgkin lymphoma (NHL) in human immunodeficiency virus (HIV)-infected patients remains high despite treatment with antiretroviral therapy (ART). Methods.?We evaluated NHL incidence in HIV-infected patients followed in the Centers for AIDS Research Network of Integrated Clinical Systems who started combination ART and achieved suppression of HIV. We estimated the hazard ratio for NHL by time-varying HIV viremia categories, accounting for time-varying CD4 cell count using marginal structural models. Results.?We observed 37 incident NHL diagnoses during 21 607 person-years of follow-up in 6036 patients (incidence rate, 171 per 100 000 person-years; 95% confidence interval [CI], 124-236). NHL incidence was high even among patients with nadir CD4 cell count &gt;200 cells/µL (140 per 100 000 person-years [95% CI, 80-247]). Compared with ?50 copies/mL, hazard ratios (HRs) for NHL were higher among those with HIV viremia of 51-500 copies/mL (HR current = 1.66 [95% CI, .70-3.94]; HR 3-month lagged = 2.10 [95% CI, .84-5.22]; and HR 6-month lagged = 1.46 [95% CI, .60-3.60]) and &gt;500 copies/mL (HR current = 2.39 [95% CI, .92-6.21]; HR 3-month lagged = 3.56 [95% CI, 1.21-10.49]; and HR 6-month lagged = 2.50 [95% CI, .91-6.84]). Current HIV RNA as a continuous variable was also associated with NHL (HR = 1.42 per log10 copies/mL [95% CI, 1.05-1.92]). Conclusions.?Our findings demonstrate a high incidence of NHL among HIV-infected patients on ART and suggest a role of HIV viremia in the pathogenesis of NHL. Earlier initiation of potent ART and maximal continuous suppression of HIV viremia may further reduce NHL risk.",
Arsenic,627842,"Exposure to inorganic arsenic in drinking water and total urinary arsenic concentration in a Chilean population Abstract: The relationship of inorganic arsenic exposure through drinking water and total urinary arsenic excretion in a nonoccupationally exposed population was evaluated in a cross-sectional study in three mayor cities of Chile (Antofagasta, Santiago, and Temuco). A total of 756 individuals in three population strata (elderly, students, and workers) provided first morning void urine specimens the day after exposure and food surveys were administered. Arsenic intake from drinking water was estimated from analysis of tap water samples, plus 24-h dietary recall and food frequency questionnaires. Multilevel analysis was used to evaluate the effects of the age group and city factors adjusted by predictor variables. Arsenic levels in drinking water and urine were significantly higher in Antofagasta compared with the other cities. City- and individual-level factors, 12% and 88%, respectively, accounted for the variability in urinary arsenic concentration. The main predictors of urinary arsenic concentration were total arsenic consumption through water and age. These findings indicate that arsenic concentration in drinking water continues to be the principal contributing factor to exposure to inorganic arsenic in the Chilean population.",
Arsenic,1350475,Assessment of concentrations of toxic elements in aquaculture food products in Malaysia Abstract: ,
Arsenic,1509327,"Activated carbon from bamboo waste modified with iron and its application in the study of the adsorption of arsenite and arsenate Abstract: Activated carbon obtained from bamboo waste was synthesised and modified with iron (BAC-Fe) and used for the removal of arsenic from aqueous solutions. Two different adsorption models were used for analysing the data. The adsorption capacities were determined for BAC-arsenite, BAC-Fe-arsenite, BAC-arsenate and BAC-Fe-arsenate, with a qmax (µg g?1) of 14.89, 19.19, 22.32 and 27.32 respectively. Adsorption capacity varied as a function of pH and modifications to the sorbent. Adsorption isotherms from an aqueous solution of arsenite and arsenates on activated carbons were determined. These adsorption isotherms were consistent with the Langmuir and Freundlich adsorption models. Adsorption kinetics followed a pseudo-first order rate equation, as did the kinetics for BAC-Fe-arsenite and BAC-Fe-arsenate adsorption.",
Arsenic,2345624,"Molecular characterization of amikacin, kanamycin and capreomycin resistance in M/XDR-TB strains isolated in Thailand Abstract: <strong>BACKGROUND: </strong>The emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) makes the treatment and control of tuberculosis difficult. Rapid detection of drug-resistant strains is important for the successful treatment of drug-resistant tuberculosis; however, not all resistance mechanisms to the injectable second-line drugs such as amikacin (AK), kanamycin (KM), and capreomycin (CAP) are well understood. This study aims to validate the mechanisms associated with AK, KM, and CAP resistance in M. tuberculosis clinical strains isolated in Thailand.<br /><br /><strong>RESULTS: </strong>A total of 15,124 M. tuberculosis clinical strains were isolated from 23,693 smear-positive sputum samples sent from 288 hospitals in 46 of 77 provinces of Thailand. Phenotypic analysis identified 1,294 strains as MDR-TB and second-line drugs susceptibility was performed in all MDR-TB strains and revealed 58 XDR-TB strains. Twenty-nine KM-resistant strains (26 XDR-TB and 3 MDR-TB) could be retrieved and their genes associated with AK, KM, and CAP resistance were investigated compared with 27 KM-susceptible strains. Mutation of the rrs (A1401G) was found in 21 out of 29 KM-resistant strains whereas mutations of eis either at C-14 T or at G-37 T were found in 5 strains. Three remaining KM-resistant strains did not contain any known mutations. Capreomycin resistance was determined in 28 of 29 KM-resistant strains. Analysis of tlyA revealed that the A33G mutation was found in all CAP-resistant strains and also in susceptible strains. In contrast, the recently identified tlyA mutation T539G and the novel Ins49GC were found in two and one CAP-resistant strains, respectively. In addition, our finding demonstrated the insertion of cytosine at position 581 of the tap, a putative drug efflux encoding gene, in both KM-resistant and KM-susceptible strains.<br /><br /><strong>CONCLUSIONS: </strong>Our finding demonstrated that the majority of KM resistance mechanism in Thai M. tuberculosis clinical strains was rrs mutation at A1401G. Mutations of the eis promoter region either at C-14 T or G-37 T was found in 5 of 29 strains whereas three strains did not contain any known mutations. For CAP resistance, 3 of 28 CAP-resistant strains contained either T539G or Ins49GC mutations at tlyA that might be associated with the resistant phenotype.",
Arsenic,915396,"Protective role of exogenous ?-lipoic acid (ALA) on hippocampal antioxidant status and memory function in rat pups exposed to sodium arsenite during the early post-natal period Abstract: The present work focussed on the effect of exogenous ?-lipoic acid (ALA) administration on retention memory and oxidative stress markers in the hippocampus subsequent to early post-natal exposure of rat pups to sodium arsenite (NaAsO(2)). Wistar rat pups were divided into the control groups receiving either no treatment (Ia) or distilled water by intraperitoneal route (i.p.) (Ib) and the experimental groups receiving either NaAsO(2) alone (1.5 and 2.0?mg/kg body wt.) (IIa, IIb) or NaAsO(2) (1.5 and 2.0?mg/kg body wt.) followed by ALA (70?mg/kg body wt.) (IIIa, IIIb) (i.p.) from post-natal day (PND) 4-15. The initial and retention transfer latency (ITL and RTL) was determined on PND 14 and 15 using elevated plus maze. The animals were sacrificed by cervical decapitation (PND 16) and the brains were obtained. The dissected out hippocampus was processed for estimation of oxidative stress markers, glutathione (GSH), and superoxide dismutase (SOD). NaAsO(2) exposure resulted in longer RTL in animal groups IIa and IIb, thereby suggestive of arsenic-induced impairment in retention memory. RTL was significantly shorter in animal groups (IIIa, IIIb) receiving ALA following NaAsO(2), thereby suggestive of improvement in retention memory. GSH and SOD levels were significantly decreased in animals receiving NaAsO(2) alone as against group Ib and administration of ALA following NaAsO(2) increased the levels of hippocampal GSH and SOD. These observations are suggestive of the role of exogenous ALA in ameliorating the adverse effects induced by NaAsO(2) exposure of rat pups on retention memory and oxidative stress markers.",
Arsenic,1020052,"Arsenic toxicity and HSP70 expression in Xenopus laevis embryos Abstract: The evaluation of the effect of trace metals on health can be difficult, because of their presence in the environment in various chemical forms. Exposure to arsenic compounds is an example of this complexity, as it can be present in the environment in inorganic and organic forms. The effects of arsenic in vertebrates are complicated by several variables, such as speciation of the element, the exposure route, and the susceptibility of the particular animal species. The embryotoxicity and teratogenicity of three arsenic species - sodium arsenite (NaAsO(2)), disodium hydrogen arsenate (Na(2)HAsO(4)) and dimethylarsinic acid [(CH3)2AsOOH] - were evaluated by the modified frog embryo teratogenic assay on Xenopus (FETAX). We also show how the classical FETAX endpoints, based on morphological and morphometrical analysis, can conveniently be integrated with the study of molecular markers. Possible changes in the expression of the mRNA for the heat-shock protein HSP70, following exposure to NaAsO(2), were examined by using the reverse transcriptase polymerase chain reaction. HSP70 mRNA is strongly induced by arsenic.",
Arsenic,1251577,"Cytotoxicity and chromosome aberrations in normal human oral keratinocytes induced by chemical carcinogens: Comparison of inter-individual variations Abstract: Normal human keratinocytes from the oral cavity were cultured in vitro in serum-free medium. Cultures from different individuals were established, and the responses of the cells to different chemicals were compared. The cells, grown at clonal densities, were treated separately with an alkylating agent (N-methyl-N'-nitro-N-nitrosoguanidine; MNNG), two arsenical salts (sodium arsenate or sodium arsenite), sodium fluoride or two polyaromatic hydrocarbons (benzo[a]pyrene or 7,12-dimethylbenz[a]-anthracene). There were no significant differences in the colony-forming efficiencies (22.8 +/- 4.2%) of control (untreated) cells from five different individuals. At selected doses, each of the chemicals reduced the colony-forming efficiencies of the treated cells. The cytotoxicity of most of the chemicals did not differ significantly among cells derived from different individuals, with the exception of sodium arsenate at two doses and sodium fluoride at the highest dose tested. Induction of chromosome aberrations by MNNG, sodium arsenite, sodium arsenate and sodium flouride was analysed with cells derived from up to nine individuals. There was little difference in the inducibilities of chromosome aberrations among cultured keratinocytes from different donors. Treatment of cells from nine donors with one dose of sodium fluoride revealed a statistically significant inter-individual variation. These findings provide a model system to study the effects of carcinogens on the target cells for oral cancers. The results can be compared with findings for cells from other epithelial tissues, since the culture conditions support the growth of keratinocytes regardless of origin. Little inter-individual variation was observed in the response of oral keratinocytes to the chemicals examined.",
Arsenic,1018540,"Determination of arsenic in blood and stomach contents by inductively coupled plasma/mass spectrometry (ICP/MS) Abstract: Inductively coupled plasma/mass spectrometry (ICP/MS) was used and evaluated for the practical analysis of the arsenic content of body fluid samples without ashing. The calibration curve for arsenic in blood solution was shown to have good sensitivity, linearity and reproducibility. Blood obtained from normal volunteers was determined by ICP/MS, and compared with that determined by atomic absorption spectrometry (AAS). The arsenic contents determined by ICP/MS showed a linear correlation with that determined by AAS. Furthermore, arsenic was determined in the blood and supernatant of stomach contents obtained from a suicide autopsy case resulting from ingestion of an arsenic compound. It was therefore concluded that ICP/MS could be used rapidly and conveniently in the field of forensic toxicology in acute metal poisoning cases.",
Arsenic,1252319,"Estimation of dietary intake of inorganic arsenic in US children Abstract: Arsenic is a natural component of the environment and is ubiquitous in soils, water, and the diet. Because dietary intake can be a significant source of background exposure to inorganic arsenic (the most toxicologically significant form), accurate intake estimates are needed to provide a context for risk management of arsenic exposure. Intake of inorganic arsenic by adults is fairly well characterized, but previous estimates of childhood intake were based on inorganic arsenic analyses in a limited number of foods (13 food types). This article estimates dietary intake for U.S. children (1 to 6 years of age) based on reported inorganic arsenic concentrations in 38 foods and in water used in cooking those foods (inorganic arsenic concentration of 0.8 mug/L), and U.S. Department of Agriculture food consumption data. This information is combined using a probabilistic software model to extract food consumption patterns and compute exposure distributions. The mean childhood dietary intake estimate for inorganic arsenic was 3.2 mug/day with a range of 1.6 to 6.2 mug/day for the 10th and 95th percentiles, respectively. For both the mean and 95th percentile inorganic arsenic intake rates, intake was predominantly contributed by grain and grain products, fruits and fruit juices, rice and rice products, and milk.",
Arsenic,1018341,"Metabolism of arsenic after acute occupational arsine intoxication Abstract: Among the elements of toxicological relevance, inorganic arsenic (As) probably exhibits the most complex metabolism, and we deemed it interesting to identify and quantify the different As species excreted after an occupational acute intoxication with arsine. For this purpose total As and five As species were determined using an hybrid analytical method coupling liquid chromatography with inductively coupled plasma mass spectrometry. The highest urinary elimination of total As was observed in the first 5 d after admission. The As species mostly excreted were monomethylarsonate (MMA), dimethylarsinate (DMA), As3+, arsenobetaine (AsB), and to a lesser extent As5+. The amount of AsB excreted in urine by the subject does not appear to be completely justified by AsB intake through food. Arsenic is excreted mainly via the urine with a clearance of 7.8 ml/h/kg and follows a triphasic model with periods of 28 h, 59 h, and 9 d, respectively. The evidence that DMA excretion culminates after a few days, when the excretion of the inorganic form is substantially reduced (while that of MMA is still elevated), seems to confirm the existence of two successive methylating enzyme activities. Furthermore, the elimination rate of As from blood follows a three-phase model and the half-lives of different species vary from about 27 to 86 h with the following gradient As5+ &lt; MMA &lt; As3+ &lt; DMA &lt; AsB.",
Arsenic,1356717,"Urinary arsenic speciation by high-performance liquid chromatography/atomic absorption spectrometry for monitoring occupational exposure to inorganic arsenic Abstract: Total urinary arsenic determinations are often used to assess occupational exposure to inorganic arsenic. Ingestion of sea food can increase the normal background levels of total arsenic in urine by up to an order of magnitude, but this arsenic has relatively little toxicity; it is tightly bound as arsenobetaine. The excretion of inorganic arsenic and its metabolites dimethylarsenic acid (DMA) and monomethylarsonic acid (MMA) is not influenced by the consumption of arsenic from sea food. Specific measurements of DMA, MMA and inorganic arsenic provide a more reliable indicator or exposure than total urinary arsenic levels. An automated atomic absorption method involving high-performance liquid chromatographic separation of the arsenic species and continuous hydride generation is described for the determination of arsenite, arsenate, DMA and MMA at ?g As l?1 levels. The method is used to study normal urinary arsenic levels in laboratory staff and arsenic excretion by exposed workers.",
Arsenic,1385066,GENOTOXICITY TESTING OF ARSENOBETAINE THE PREDOMINANT FORM OF ARSENIC IN MARINE FISHERY PRODUCTS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM SALMONELLA-TYPHIMURIUM CHINESE HAMSTER V-79 CELL SEAFOOD MUTAGENESIS,
Arsenic,1023899,"HERG channel trafficking Abstract: Mutations in the cardiac potassium channel hERG/IKr cause inherited long QT syndrome with increased susceptibility to ventricular arrhythmias. Several mutations in hERG produce trafficking-deficient channels that are retained in the endoplasmic reticulum (ER). Surface expression of certain mutations (i.e. hERG G601S) can be restored by specific channel blockers. Although hERG currents have been studied extensively, little is known about proteins in the processing pathway. Using biochemical and electrophysiological assays we show that the cytosolic chaperones Hsp70 and Hsp90 interact transiently with wild-type hERG. Inhibition of Hsp90 prevents maturation and reduces hERG/IKr currents. Trafficking-deficient mutants remain tightly associated with chaperones in the ER until trafficking is restored, e.g. by channel blockers. hERG/chaperone complexes represent novel targets for therapeutic compounds with cardiac liability such as arsenic, which is used in the treatment of leukaemias. Arsenic interferes with the formation of hERG/chaperone complexes and inhibits hERG maturation causing ECG abnormalities. We conclude that Hsp9O and Hsp70 are crucial for productive folding of wild-type hERG. Therapeutic compounds that inhibit chaperone function produce a novel form of acquired long QT syndrome not by direct channel block but by reduced surface expression due to an acquired trafficking defect of hERG.",
Arsenic,1677607,"Bacteria diversity and arsenic mobilization in rock biofilm from an ancient gold and arsenic mine Abstract: In this paper we characterize the biofilm community from an ancient Z?oty Stok gold and arsenic mine. Bacterial diversity was examined using a culture-independent technique based on 16S rRNA gene amplification, cloning and sequencing. We show that unexpectedly the microbial diversity of this community was extremely high (more than 190 OTUs detected), with the most numerous members from Rhizobiales (?-Proteobacteria). Although the level of rock biofilm diversity was similar to the microbial mat community we have previously characterized in the same adit, its taxonomic composition was completely different. Detailed analysis of functional arrA and aioA genes, chemical properties of siderophores found in pore water as well as the biofilm chemical composition suggest that the biofilm community contributes to arsenic pollution of surrounding water in a biogeochemical cycle similar to the one observed in bacterial mats. To interpret our results concerning the biological arsenic cycle, we applied the theory of ecological pyramids of Charles Elton.",
Arsenic,2298698,"Modelling oxyanion adsorption on ferralic soil. 2. Chromate, selenate, molybdate, and arsenate adsorption Abstract: High levels of oxyanions are found in the soil environment, often as a result of human activity. At high concentrations, oxyanions can be harmful to both humans and wildlife. Information about the interactions between oxyanions and natural samples is essential for understanding the bioavailability, toxicity and transport of these compounds in the environment. In the present study, we investigated the reactivity of different oxyanions (AsO4 , MoO4 , SeO4 and CrO4 ) at different pH in two horizons of a ferralic soil. By combining available microscopic data on iron oxides with the macroscopic data obtained here, we were able to use the charge distribution (CD) model to accurately describe the adsorption of these four oxyanions and thus to determine the surface speciation. The CD model was previously calibrated and evaluated using phosphate adsorption/desorption data. The adsorption behaviour on the ferralic soil is mainly controlled by the natural iron oxides present and it is qualitatively analogous to that exhibited by synthetic iron oxides. The highest adsorption was found for arsenate ions whereas the lowest was found for selenate, with chromate and molybdate ions showing an intermediate behaviour. Environ Toxicol Chem © 2014 SETAC.",
Arsenic,1347661,Cell stage specificity of ultraviolet-light and sodium arsenite on the induction of chromosome-aberrations Abstract: ,
Arsenic,1597451,"Removal of boron and arsenic from petrochemical wastewater by using aquatic booster as adsorbent Abstract: The potential to remove boron and arsenic from petrochemical wastewater by using aquatic booster was investigated in batch experiment process and the results were measured by inductively coupled plasma mass spectrometry (ICPMS). The main parameters influencing arsenic and boron adsorption onto the aquatic booster were contact time, size of particle, agitation speed, and dosage. The initial concentration of boron and arsenic was fixed by changing contact time (120-480 minutes), agitation speed (0-120 rpm), aquatic booster dosage (0-55 g/L), and size of particle (2 mm, 1 mm, and 0.60 mm). The adsorption efficiency of arsenic and boron increases with longer contact time as well as more aquatic booster dosage and higher agitation speed. However, it tends to achieve equilibrium once the active sites of the adsorbent are fully occupied. On the other hand, adsorption efficiency decreases with larger adsorbent particle size. The equilibrium time for both boron and arsenic is 390 minutes. The removal efficiency for boron is around 60.36% by 35g/L dosage, 80 rpm and a particle size of 0.60 mm at of 390 minutes. As for the arsenic, the condition where it gives the removal percentage around 71.83% is that particle size of 0.6 mm, 300 minutes contact time, agitation speed of 80 rpm and dosage of 45g/L. The modeling study shows that the adsorption isotherms for both metals onto aquatic booster are Freundlich type.",
Arsenic,1936083,"Metal stoichiometry of isolated and arsenic substituted metallothionein: PIXE and ESI-MS study Abstract: The stoichiometric analysis of the metal induced Metallothionein (MT) is pertinent for understanding the metal-MT interactions. Despite innumerable publications on MT, the literature addressing these aspects is limited. To bridge this gap, PIXE and ESI-MS analysis of the commercial rabbit liver MT1 (an isoform of MT), zinc induced isolated rat liver MT1, apo and Arsenic substituted rabbit liver MT1 have been carried out. These techniques in combination provide information about number and the signature of all the metal ions bound to MT. By using ESI-MS in the rabbit MT1, ions of Zn n MT1 (n = 0, 1, 4, 5, 6, 7) whereas, in rat MT1, the Zn1MT1 and Zn5MT1 ions are observed. PIXE analysis shows that some copper along with zinc is also present in the rabbit as well as rat MT1 which could not be assessed with ESI-MS. During As metallation reaction with rabbit MT1, with increase in arsenic concentration, the amount of arsenic bound to MT1 also increases, though not proportionally. The presence of both Zn and Cu in MT1 on Zn supplementation can be related to the role of MT in Zn and Cu homeostasis. Further, the presence of partially metallated MT1 suggests that MT1 may donate fractional amount of metal from it's fully metallated form to other proteins where Zn acts as a cofactor.",
Arsenic,627253,"Effects and Interactions of low doses of arsenic and UVB on keratinocyte apoptosis Abstract: Although arsenic and ultraviolet light B (UVB) are both causes for skin cancers, lesions of arsenic-induced Bowen's disease are often confined to sun-protected skin. UVB may play a modulatory role in skin carcinogenesis by arsenic. The purpose of this study was to evaluate the effects and interactions of arsenic and UVB on cell cycle progression and apoptosis. Cultured human keratinocytes were treated with sodium arsenite (1 microM) and/or UVB (50 mJ/cm(2)) irradiation in different combinations: (i) arsenic alone, (ii) UVB alone, (iii) arsenic followed by UVB (As-UVB), and (iv) UVB followed by arsenic (UVB-As) treatments. Cell cycle analysis and BrdU pulsing revealed S phase arrest in all treatment groups and growth arrest in As-UVB and UVB-As groups. The terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling assay showed a higher apoptosis rate in the UVB-As group as compared to that of the As-UVB and UVB groups. UVB irradiation significantly decreased Bcl-2 expression. In either the As-UVB or the UVB-As group, the expression of Bcl-2 was further suppressed as compared to the UVB group. The caspase-3, -8, and -9 relative activities were all increased in the UVB group; however, arsenic significantly enhanced caspase-8 and -3 relative activities in UVB-irradiated keratinocytes (the UVB-As group). Pretreatment with the caspase inhibitor(s) rescued the keratinocytes viability to different degrees with the least in the UVB-As group. Our findings revealed that arsenic enhances UVB-induced keratinocyte apoptosis via suppression of Bcl-2 expression and stimulation of caspase-8 activity. Combined UVB and arsenic treatment resulted in the antiproliferative and proapoptotic effects in keratinocytes. Our results provide the explanation for the rare occurrences of arsenical cancers in the sun-exposed skin and the potential therapeutic role of UVB in arsenic-induced Bowen's disease.",
Arsenic,2343454,"Arsenic and copper stabilisation in a contaminated soil by coal fly ash and green waste compost Abstract: In situ metal stabilisation by amendments has been demonstrated as an appealing low-cost remediation strategy for contaminated soil. This study investigated the short-term leaching behaviour and long-term stability of As and Cu in soil amended with coal fly ash and/or green waste compost. Locally abundant inorganic (limestone and bentonite) and carbonaceous (lignite) resources were also studied for comparison. Column leaching experiments revealed that coal fly ash outperformed limestone and bentonite amendments for As stabilisation. It also maintained the As stability under continuous leaching of acidic solution, which was potentially attributed to high-affinity adsorption, co-precipitation, and pozzolanic reaction of coal fly ash. However, Cu leaching in the column experiments could not be mitigated by any of these inorganic amendments, suggesting the need for co-addition of carbonaceous materials that provides strong chelation with oxygen-containing functional groups for Cu stabilisation. Green waste compost suppressed the Cu leaching more effectively than lignite due to the difference in chemical composition and dissolved organic matter. After 9-month soil incubation, coal fly ash was able to minimise the concentrations of As and Cu in the soil solution without the addition of carbonaceous materials. Nevertheless, leachability tests suggested that the provision of green waste compost and lignite augmented the simultaneous reduction of As and Cu leachability in a fairly aggressive leaching environment. These results highlight the importance of assessing stability and remobilisation of sequestered metals under varying environmental conditions for ensuring a plausible and enduring soil stabilisation.",
Arsenic,627983,"A comparative study of the sub-chronic toxic effects of three organic arsenical compounds on the urothelium in F344 rats; gender-based differences in response Abstract: Epidemiological studies indicated that human arsenic exposure can induce urinary bladder cancer. Methylation of inorganic arsenic can generate more reactive and toxic organic arsenical species. In this regard, it was recently reported that the methylated arsenical metabolite, dimethylarsinic acid [DMA(V)], induced urinary bladder tumors in rats. However, other methylated metabolites, like monomethylarsonic acid [MMA(V)] and trimethylarsine oxide (TMAO) were not carcinogenic to the urinary bladder. In order to compare the early effects of DMA(V), MMA(V), and TMAO on the urinary bladder transitional cell epithelium at the scanning electron microscope (SEM) level, we investigated the sub-chronic (13 weeks) toxicological effects of MMA(V) (187 ppm), DMA(V) (184 ppm), TMAO (182 ppm) given in the drinking water to male and female F344 rats with a focus on the urinary bladder in this study. Obvious pathological changes, including ropy microridges, pitting, increased separation of epithelial cells, exfoliation, and necrosis, were found in the urinary bladders of both sexes, but particularly in females receiving carcinogenic doses of DMA(V). Urine arsenical metabolic differences were found between males and females, with levels of MMA(III), a potential genotoxic form, higher in females treated with DMA(V) than in males. Thus, this study provides clear evidence that DMA(V) is more toxic to the female urinary bladder, in accord with sensitivity to carcinogenesis. Important gender-related metabolic differences including enhanced presentation of MMA(III) to the urothelial cells might possibly account for heightened sensitivity in females. However, the potential carcinogenic effects of MMA(III) need to be further elucidated.",
Arsenic,627614,"Enhanced frequency of micronuclei in individuals exposed to arsenic through drinking water in West Bengal, India Abstract: In West Bengal, India arsenic in ground water has been found to be above the maximum permissible limit in seven districts covering an area of 37,493km2. In the present study, evaluation of the micronuclei (MN) formation in oral mucosa cells, urothelial cells and peripheral blood lymphocytes was carried out in the symptomatic individuals exposed to arsenic through drinking water. Forty five individuals with cutaneous signs of arsenicism from four affected districts (368.11 microg/l of As in drinking water) were considered as the exposed group and 21 healthy individuals with no symptoms of arsenic poisoning and residing in two unaffected districts (5.49 microg/l of As) were considered as controls. The exposed and control groups had similar age distribution and socioeconomic status. Standardised questionnaires were utilised and medical examination was conducted to ascertain exposure history, sociodemographic characteristics, diet, health, medication, addiction and chief symptoms in the study participants. Arsenic exposure was confirmed by measuring the arsenic content in the drinking water, nails, hair and urine samples from the volunteers. Arsenic contents in the urine, nail and hair in the exposed group were 24.45 microg/l, 12.58 and 6.97 microg/g, respectively which were significantly high in comparison to corresponding control group values of 4.88 microg/l, 0.51 and 0.34 microg/g, respectively. Exposed individuals showed a statistically significant increase in the frequency of MN in oral mucosa, urothelial cells and lymphocytes (5.15, 5.74 and 6.39/1000 cells, respectively) when compared with the controls (0.77, 0.56 and 0.53/1000 cells, respectively). Thus, the above results indicate that the symptomatic individuals exposed to arsenic through drinking water in this region have significant cytogenetic damage.",
Arsenic,2278549,"Embryonic arsenic exposure reduces the number of muscle fibers in killifish (Fundulus heteroclitus) Abstract: Arsenic is a contaminant of drinking water and has been correlated with adverse developmental outcomes such as low birth weight, reduced weight gain, and altered locomotor activity. Previous research has shown that killifish (Fundulus heteroclitus) exposed to high arsenic levels during embryogenesis had smaller muscle fiber diameters. The current study was designed to determine whether changes in muscle fibers persisted, were exacerbated, or resolved over time. Killifish embryos were exposed to 0-5 ppm arsenite and, upon hatching, were transferred into either clean water or continued receiving the same exposure to arsenic for up to 16 weeks. Arsenic significantly decreased the weight of both embryonic-only exposed juveniles and continuously exposed juveniles between 4 and 16 weeks of development at concentrations as low as 0.8 ppm. Although arsenite exposure increased the percentage of small diameter fibers during the early weeks, fiber diameters returned to control levels in the embryonic-only exposed fish. However, muscle fiber density was still reduced to 85.7%, 80.3%, and 73.8% of control for the 0.8, 2, and 5 ppm embryonic-only exposure groups, respectively, even after 16 weeks of development. These results indicate that while continuous exposure to arsenic may alter the size of muscle fibers, embryonic-only exposure to arsenic has lasting effects on the number of muscle fibers formed.",
Arsenic,1070430,"Baseline health parameters and species comparisons among free-ranging Atlantic sharpnose (Rhizoprionodon terraenovae), bonnethead (Sphyrna tiburo), and spiny dogfish (Squalus acanthias) sharks in Georgia, Florida, and Washington, USA Abstract: Sharks are of commercial, research, conservation, and exhibition importance but we know little regarding health parameters and population status for many species. Here we present health indicators and species comparisons for adults of three common wild-caught species: 30 Atlantic sharpnose sharks (Rhizoprionodon terraenovae) and 31 bonnethead sharks (Sphyrna tiburo) from the western Atlantic, and 30 spiny dogfish sharks (Squalus acanthias) from the eastern Pacific. All animals were captured during June-July 2009 and 2010. Median values and preliminary reference intervals were calculated for hematology, plasma biochemistry, trace nutrients, and vitamin A, E, and D concentrations. Significant differences, attributable to physiologic differences among the species, were found in the basic hematologic and plasma biochemistry variables. Significant species differences in arsenic and selenium plasma concentrations were found and appear to coincide with diet and habitat variability among these three species. Vitamin E was significantly higher in the bonnethead shark, again related to the foraging ecology and ingestion of plant material by this species. The Atlantic sharpnose had significantly higher vitamin A concentrations, supported by the higher proportion of teleosts in the diet. Vitamin D was below the limit of quantification in all three species. These preliminary reference intervals for health variables can be used to assess and monitor the population health and serve as indicators of nutritional status in these populations of wild elasmobranchs.",
Arsenic,1019315,"Studies on the mechanisms of arsenic-induced self tolerance developed in liver epithelial cells through continuous low-level arsenite exposure Abstract: Arsenic (As) is a human carcinogen. Our prior work showed that chronic (&gt;18 weeks) low level (500 nM) arsenite (As3+) exposure induced malignant transformation in a rat liver epithelial cell line (TRL 1215). In these cells, metallothionein (MT) is hyper-expressible, a trait often linked to metal tolerance. Thus, this study examined whether the adverse effects of arsenicals and other metals were altered in these chronic arsenite-exposed (CAsE) cells. CAsE cells, which had been continuously exposed to 500 nM arsenite for 18 to 20 weeks, and control cells, were exposed to As3+, arsenate (As5+), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), antimony (Sb3+), cadmium (Cd2+), cisplatin (cis-Pt), and nickel (Ni2+) for 24 h and cell viability was determined by metabolic integrity. The lethal concentration for 50% of exposed cells (LC50) for As3+ was 140 microM in CAsE cells as compared to 26 microM in control cells, a 5.4-fold increase in tolerance. CAsE cells were also very tolerant to the acute toxic effects of As5+ (LC50 &gt; 4000 microM) compared to control (LC50 = 180 microM). The LC50 for DMA was 4.4-fold higher in CAsE cells than in control cells, but the LC50 for MMA was unchanged. There was a modest cross-tolerance to Sb3+, Cd2+, and cis-Pt in CAsE cells (LC50 1.5-2.0-fold higher) as compared to control. CAsE cells were very tolerant to Ni2+ (LC50 &gt; 8-fold higher). Culturing CAsE cells in As(3+)-free medium for 5 weeks did not alter As3+ tolerance, implicating an irreversible phenotypic change. Cellular accumulation of As was 87% less in CAsE cells than control and the accumulated As was more readily eliminated. Although accumulating much less As, a greater portion was converted to DMA in CAsE cells. Altered glutathione (GSH) levels were not linked with As tolerance. A maximal induction of MT by Zn produced only a 2.5-fold increase in tolerance to As3+ in control cells. Cell lines derived from MT normal mice (MT+/+) were only slightly more resistant (1.6-fold) to As3+ than cells from MT null mice (MT-/-). These results show that CAsE cells acquire tolerance to As3+, As5+, and DMA. It appears that this self-tolerance is based primarily on reduced cellular disposition of the metalloid and is not accounted for by changes in GSH or MT.",
Arsenic,558347,"Arsenic-induced alteration in the expression of genes related to type 2 diabetes mellitus Abstract: Chronic exposure to high concentrations of arsenic in drinking water is associated with an increased risk for developing type 2 diabetes. The present revision focuses on the effect of arsenic on tissues that participate directly in glucose homeostasis, integrating the most important published information about the impairment of the expression of genes related to type 2 diabetes by arsenic as one of the possible mechanisms by which it leads to the disease. Many factors are involved in the manner in which arsenic contributes to the occurrence of diabetes. The reviewed studies suggest that arsenic might increase the risk for type 2 diabetes via multiple mechanisms, affecting a cluster of regulated events, which in conjunction trigger the disease. Arsenic affects insulin sensitivity in peripheral tissue by modifying the expression of genes involved in insulin resistance and shifting away cells from differentiation to the proliferation pathway. In the liver arsenic disturbs glucose production, whereas in pancreatic beta-cells arsenic decreases insulin synthesis and secretion and reduces the expression of antioxidant enzymes. The consequences of these changes in gene expression include the reduction of insulin secretion, induction of oxidative stress in the pancreas, alteration of gluconeogenesis, abnormal proliferation and differentiation pattern of muscle and adipocytes as well as peripheral insulin resistance.",
Arsenic,627942,"Arsenic-induced DNA hypomethylation affects chromosomal instability in mammalian cells Abstract: Early genetic instability induced in dividing V79-Cl3 Chinese hamster cells by inorganic arsenic, as demonstrated in our previous investigation, was evidenced by aneuploidy and nuclear abnormalities, but not by chromosomal rearrangements. Here we report the results of cytogenetic and morphological analyses performed on the progeny of cells dividing at the end of sodium arsenite treatment after they had been expanded through 120 generations (ASO cells) and then cloned. The acquired genetic instability persisted and was increased by highly unstable chromosomal rearrangements, namely dicentric chromosomes and telomeric associations, which were not seen following acute exposure. A peculiar finding was the preferential involvement of a particular chromosome in dicentric rearrangements observed in some isolated ASO clones. Interestingly, by immunostaining with anti-5-methylcytosine antibodies the genome-wide DNA hypomethylation, induced by arsenic immediately after the acute treatment, was found to affect those ASO clones characterized by aneuploidy and chromosomal rearrangements. These findings demonstrate that short-term exposure to arsenic has long-term effects and suggest that genome-wide DNA hypomethylation enhances genetic instability.",
Arsenic,1337303,"Intact As(4) Tetrahedra Coordinated Side-On to Metal Cations Abstract: Extremely light sensitive yellow arsenic (As(4) ) reacts with a weakly coordinated silver cation to afford [Ag(?(2) -As(4) )(2) ](+) [Al{OC(CF(3) )(3) }(4) ](-) as the first known homoleptic arsenic complex. DFT calculations and Raman spectroscopy clearly indicate the coordination of two intact As(4) tetrahedra. This unprecedented complex is used as an As(4) transfer agent, which is demonstrated by the synthesis of [(PPh(3) )Au(?(2) -As(4) )](+) [Al{OC(CF(3) )(3) }(4) ](-) .",
Arsenic,1034028,Levels of arsenic in liver cirrhosis Abstract: The present studies were conducted to determine the arsenic levels in liver specimens obtained at autopsy from human subjects suffering from liver cirrhosis. Arsenic content was determined using the neutron activation analysis technique. Increased levels of arsenic were found in cirrhotic liver samples including alcoholic cirrhosis. Various surveys were conducted in different places to find the cause for high arsenic in patients with alcoholic cirrhosis. It was found that patients were consuming 'home-made brew' which was contaminated with arsenic. The study suggests that elevated levels of arsenic may be associated with liver damage in cirrhotic patients.,
Arsenic,735015,"Effects of DNMT and MEK inhibitors on the expression of RECK, MMP-9, -2, uPA and VEGF in response to arsenite stimulation in human uroepithelial cells Abstract: It has been shown that the ingestion of arsenic-contaminated drinking water is closely correlated with risk of several cancers. The mechanism of arsenic-induced carcinogenesis is still unclear. The RECK, MMP-9, -2, uPA and VEGF are the most common dysregulation in human tumors and cancer cell lines. However, the effect of arsenite on these markers expression and the molecular mechanism are still unclear. The purpose of the study was to investigate the relationship between the expression of RECK, MMP-9, -2, uPA and VEGF in arsenite-treated human and rat uroepithelial cells. In addition, we also observed and compared the expression of these markers in urothelial carcinoma (UC) from Blackfoot disease (BFD) areas and non-Blackfoot disease (non-BFD) areas. We analyzed the arsenite causing cell proliferation, RECK, MMP-9, -2, uPA and VEGF expression by Western blotting, immunocytochemistry (ICC), RT-PCR, and gelatin zymography. We demonstrated the effect of arsenite on methylation status of RECK promoter as determined by using methylation-specific PCR (MSP). Our results show that arsenite downregulation of RECK is caused by epigenetic inactivation via promoter hypermethylation, and that levels of MMP-9, -2, uPA and VEGF were increased in human uroepithelial cells (SV-HUC-1). However, when the cells were pretreated with inhibitors (5-aza-CdR or U0126) for 24h, the effects of arsenite on RECK, MMP-9, -2, uPA and VEGF expression were suppressed. Indeed, we also found significant differences between the expression of RECK, MMP-9, -2, uPA and VEGF in UC from the BFD areas and non-BFD areas (p=0.006, 0.007, 0.003, &lt;0.001 and 0.001 respectively), as detected by immunohistochemistry (IHC). In in vivo study, our results showed the RECK protein expression was reduced and the expression of MMP-9, -2, uPA and VEGF increased in arsenite treatment groups. In conclusion, our results support the notion that arsenite might cause the histologic changes, RECK, MMP-9, -2, uPA and VEGF dysregulation through epigenetic inactivation and ERK1/2 activation in SV-HUC-1 cells. These findings may provide a better understanding of the urothelial carcinogenesis of arsenite.",
Arsenic,1337622,"Arsenic and peripheral blood count in workers exposed to urban stressors Abstract: Objectives. Previous studies have shown that arsenic at high doses can alter the hematopoietic system. The purpose of the present study is to see whether the same problems may be caused by chronic exposure to low doses. Materials and Methods. A sample of 349 policemen of a big urban city was divided into 3 groups according to levels of urinary arsenic. The subjects were further divided according to gender, smoking habits, and work task. We calculated indices of correlation (r) and multiple linear regression (?), between urinary arsenic, RBC, WBC, HB, HT, MCV, MCH, MCHC, platelets, reticulocytes and leukocyte formula (percentage of lymphocytes, monocytes, neutrophils, eosinophils and basophils). It was also calculated Student's t and chi-square test between the various groups to check for any differences. Results. We found several statistically significant indices of correlation and regression (ptwo-tailed <0.05) between urinary arsenic, red blood cells, white blood cells, hemoglobin, hematocrit, reticulocytes, and all the cell lines of the white series. Conclusions. Chronic exposure to low doses of arsenic seems to cause decrease in red blood cells, hematocrit and hemoglobin. However, this response is dependent on the amount of absorbed dose, according to an ormetic mechanism. With regard to the white series, arsenic seems to provoke an inflammatory response; the scarcity of literature"" available, and the great variety of results, however, not allow us to definitely characterize the damage caused by this metal on white series. Clin Ter 2012; 163(5):e293-302.",
Arsenic,1345418,"Geochemical behaviour of some heavy metals of the Grot flotation tailing, Southeast Serbia Abstract: ",
Arsenic,627922,"Human nails as a biomarker of arsenic exposure from well water in Inner Mongolia: comparing atomic fluorescence spectrometry and neutron activation analysis Abstract: Arsenic (As) is found naturally in the geological strata within the Ba Men Region of Inner Mongolia, China. A study was conducted to compare the total As measurements from two analytical techniques: instrumental neutron activation analysis (INAA) and atomic fluorescence spectrometry (AFS), and to verify nails as an exposure biomarker in this population. In 1999, nail and water samples were collected in a pilot study. Fingernails and toenails were pooled from 32 participants and analysed for total As by both INAA and AFS. Mean nail As values were 14.8+/-2.4 and 19.4+/-2.8 microg g-1 (+/-SEM) for INAA and AFS, respectively. Results from these two methods were significantly correlated (r=0.93, p<0.0001). In 2000, a second study was conducted and INAA was used to measure total As in toenails from 314 Ba Men residents. Well water samples were collected from 121 households and analysed by AFS. A significant correlation was observed between toenail and well water As (r=0.84, p<0.0001). Based on the results, INAA was significantly correlated with AFS and proved to be a reliable measure of nail As levels. In this population, toenail samples are a useful internal As exposure biomarker from drinking water sources.",
Arsenic,1936101,"Trace metal and metalloid contamination levels in soils and in two native plant species of a former industrial site: evaluation of the phytostabilization potential Abstract: This study aimed at identifying the extent and type of contamination of a former lead smelting site in the area of Marseille, France, dating from the industrial revolution, and to evaluate environmental hazards and opportunities for phytoremediation, a promising sustainable technology. Amongst the native plants growing in this semiarid shrub ecosystem, two perennials Globularia alypum L. and Rosmarinus officinalis L. were selected. Twenty-one soil/plant couples were collected and seventeen additional soil samples were added to better characterize the soil pollution of the area. A multi-contamination by Pb, As, Sb, Zn, Cu was demonstrated, with huge variations within the contamination levels. The soils highest concentrations were encountered along the horizontal chimney and on the slag heaps area. However, both sites differed from each other. The former was characterized by the highest Pb, As and Sb concentrations that could reach 130, 7.0 and 9.0gkg(-1) respectively, the latter, by high Cu, Fe, Mn, S concentrations, even if it was also heavily contaminated by Pb and Zn. G. alypum and R. officinalis were shown to be metal-tolerant and to accumulate trace metals and As. Due to the low bioconcentration and translocation factors determined, both species may not be used for phytoextraction, but seem to be good candidates for phytostabilization.",
Arsenic,1579379,"Natural contamination by As and heavy metals in soil, their bio-accumulation and potential sources: the case of a travertine limestone quarry, Greece Abstract: ",
Arsenic,1367500,"Inhibition of ubiquitin-protein ligase (E3) by mono- and bifunctional phenylarsenoxides. Evidence for essential vicinal thiols and a proximal nucleophile Abstract: Trivalent arsenoxides bind to vicinal thiol groups of proteins. We showed previously that the simplest trivalent arsenoxide, inorganic arsenite, inhibits ubiquitin-dependent protein degradation in rabbit reticulocyte lysate (Klemperer, N.S., and Pickart, C.M. (1989) J. Biol. Chem. 264, 19245-19242). We now show that, relative to arsenite, phenylarsenoxides are 10-165-fold more potent inhibitors of protein degradation in the same system (K0.5 for inhibition by p-aminophenylarsenoxide was 3.5-20 microM, depending on the substrate). In the ubiquitin-dependent proteolytic pathway, covalent ligation of ubiquitin to protein substrates targets the latter for degradation. In certain cases, specificity in ubiquitin-substrate conjugation depends critically upon the properties of ubiquitin-protein ligase or E3. Among other effects, p-aminophenylarsenoxide decreased the steady-state level of ubiquitinated human alpha-lactalbumin; this is a substrate which is acted upon directly by ubiquitin-protein ligase-alpha (E3-alpha). This finding suggests that phenylarsenoxides (unlike arsenite) inhibit E3. Several other lines of evidence confirm this conclusion. 1) A complex of E3-alpha and the 14-kDa ubiquitin-conjugating (E2) isozyme binds to phenylarsenoxide-Sepharose resin, with the E3 component of the complex mediating binding. 2) p-Aminophenylarsenoxide inhibited isolated E3 (K0.5 approximately 50 microM); inhibition was readily reversed by addition of dithiothreitol (which contains a competing vicinal thiol group), but not by beta-mercaptoethylamine (a monothiol). 3) A bifunctional phenylarsenoxide (bromoacetylaminophenylarsenoxide) rapidly and irreversibly inactivated E3; bromoacetyl aniline, which lacks an arsenoxide moiety, did not inhibit E3. These results suggest that E3 possesses essential vicinal thiol groups and that there is a reactive nucleophile proximal to the vicinal thiol site. The bifunctional phenylarsenoxide should be a useful tool for probing the relationship between structure and function in E3. As expected from prior results with arsenite, p-aminophenylarsenoxide was also a potent inhibitor of the turnover of ubiquitin-(human) alpha-lactalbumin conjugates.",
Arsenic,1380122,"Coordinate regulation of enzyme markers for inflammation and for protection against oxidants and electrophiles Abstract: An elaborate network of highly inducible phase 2 proteins protects aerobic cells against the cumulative damaging effects of reactive oxygen intermediates and toxic electrophiles, which are the major causes of malignancy and chronic degenerative diseases. Many chemical and phytochemical agents, all of which react with thiol groups, induce the phase 2 response through their reactivity with critical cysteine thiols of Keap1. We recently found that the anti-inflammatory potencies (suppression of iNOS and COX-2 expression) of a series of triterpenoids with Michael reaction centers were closely correlated with the potencies of these agents to induce the phase 2 response. We now report that representatives of seven recognized chemical classes of inducers, including isothiocyanates, bisbenzylidenes, arsenicals, heavy metals, and vicinal dithiols, showed highly correlated inducer and anti-inflammatory potencies spanning more than six orders of magnitude of concentrations in established cells and in primary mouse peritoneal macrophages. Potency measurements were expressed as the D(m) values (median effect concentration) by use of the Median Effect Equation. Whereas the phase 2 induction required the functional integrity of both the repressor Keap1 and the transcription factor Nrf2, the effectiveness of inducers in blocking the up-regulation of iNOS by inflammatory cytokines was related to the nature of the cytokine and the inducer concentration. These studies identify suppression of inflammation as a consistent property of inducers of the phase 2 response and strongly suggest that this property is a central aspect of their chemoprotective actions.",
Arsenic,1017151,"Seafood intake and urine concentrations of total arsenic, dimethylarsinate and arsenobetaine in the US population Abstract: <strong>BACKGROUND: </strong>Seafood is the main source of organic arsenic exposure (arsenobetaine, arsenosugars and arsenolipids) in the population. Arsenosugars and arsenolipids are metabolized to several species including dimethylarsinate (DMA).<br /><br /><strong>OBJECTIVE: </strong>Evaluate the association of seafood intake with spot urine arsenic concentrations in the 2003-2006 National Health Nutrition and Examination Survey (NHANES).<br /><br /><strong>METHODS: </strong>We studied 4276 participants ? 6 years. Total arsenic was measured using inductively coupled plasma dynamic reaction cell mass spectrometry (ICPMS). Urine DMA and arsenobetaine were measured by high-performance liquid chromatography coupled with ICPMS.<br /><br /><strong>RESULTS: </strong>Participants reporting seafood in the past 24-h had higher urine concentrations of total arsenic (median 24.5 vs. 7.3 ?g/L), DMA (6.0 vs. 3.5 ?g/L), arsenobetaine (10.2 vs. 0.9 ?g/L) and total arsenic minus arsenobetaine (11.0 vs. 5.5 ?g/L). Participants reporting seafood ? 2/wk vs. never during the past year had 2.3 (95% confidence interval 1.9, 2.7), 1.4 (1.2, 1.6), 6.0 (4.6, 7.8) and 1.7 (1.4, 2.0) times higher (p-trend &lt;0.001) concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine, respectively. In participants without detectable arsenobetaine and in analyses adjusted for arsenobetaine, seafood consumption in the past year was not associated with total arsenic or DMA concentrations in urine.<br /><br /><strong>CONCLUSION: </strong>Seafood intake was a major determinant of increased urine concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine in the US population. Epidemiologic studies that use total arsenic, DMA, the sum of inorganic arsenic, methylarsonate and DMA, and total arsenic minus arsenobetaine as markers of inorganic arsenic exposure and/or metabolism need to address seafood intake.",
Arsenic,1019193,"Occurrence of monomethylarsonous acid in urine of humans exposed to inorganic arsenic Abstract: Monomethylarsonous acid (MMA(III)) has been detected for the first time in the urine of some humans exposed to inorganic arsenic in their drinking water. Our experiments have dealt with subjects in Romania who have been exposed to 2.8, 29, 84, or 161 microg of As/L in their drinking water. In the latter two groups, MMA(III) was 11 and 7% of the urinary arsenic while the monomethylarsonic acid (MMA(V)) was 14 and 13%, respectively. Of our 58 subjects, 17% had MMA(III) in their urine. MMA(III) was not found in urine of any members of the group with the lowest level of As exposure. If the lowest-level As exposure group is excluded, 23% of our subjects had MMA(III) in their urine. Our results indicate that (a) future studies concerning urinary arsenic profiles of arsenic-exposed humans must determine MMA(III) concentrations, (b) previous studies of urinary profiles dealing with humans exposed to arsenic need to be re-examined and re-evaluated, and (c) since MMA(III) is more toxic than inorganic arsenite, a re-examination is needed of the two hypotheses which hold that methylation is a detoxication process for inorganic arsenite and that inorganic arsenite is the major cause of the toxicity and carcinogenicity of inorganic arsenic.",
Arsenic,1390685,"Squamous epithelioma probably due to tar ointment in a case with psoriasis Abstract: A case of squamous epithelioma arising on a patch of psoriasis in a 31 year old male was investigated. The patient presented with a 2 centimeter lump over the head of the right fibula. The lesion was raised 3 to 4 millimeters above the skin surface; the edge was firm and rolled, and the center showed slight ulceration without discharge. There was also a diffuse discoid psoriasis and a marked tar acne with one or two tar mollusca. No history of arsenic administration was found, and the only agent applied to the skin that might have been carcinogenic was an ointment containing salicylic-acid (69727), oleated-mercury (1191806), coal-tar, and an emulsifying base. Lesions appeared 14 days after initiation of tar ointment application. The patient used this ointment for 3 months before seeking medical advise. The epitheliomatous lesion was excised, and the diagnosis of squamous carcinoma was confirmed histologically. The author concludes that the continued insult to the skin of the tar ointment is the essential factor in the production of malignant change.",
Arsenic,2233932,"Natural and anthropogenic factors affecting the groundwater quality in Serbia Abstract: Various chemometric techniques were used to analyze the quality of groundwater data sets. Seventeen water quality parameters: the cations Na, K, Ca, Mg, the anions Cl, SO4, NO3, HCO3 and nine trace elements Pb, As, Mn, Ni, Cu, Cd, Fe, Zn and Cr were measured at 66 different key sampling sites in ten representative areas (low land-Northern Autonomous Province of Serbia, Vojvodina and central Serbia) for the summer period of 2009. HCA grouped the sample sites into four clusters based on the similarities of the characteristics of the groundwater quality. DA showed two parameters, HCO3 and Zn, affording more than 90% correct assignments in the spatial analysis of four/three different regions in Serbia. Factor analysis was applied on the log-transformed data sets and allowed the identification of a reduced number of factors with hydrochemical meaning. The results showed severe pollution with Mn, As, NO3, Ni, Pb whereby anthropogenic origin of these contaminants was indicated. The pollution comes from both scattered point sources (industrial and urban effluent) and diffuse source agricultural activity. These samples may not be suitable for human consumption; the water quality belongs to class III/IV (contaminated). The Fe anomalies (7.1mg/L) in the water from the Vetrnica site can be attributed to natural sources, such as the dissolution of rock masses and rock fragments. The serious groundwater contamination with As (25.7-137.8 ?g/L) in the area of Banat (Northern Autonomous Province of Serbia, Vojvodina) and a sample No. 9 at the Great Morava River requires urgent attention.",
Arsenic,1347250,"Micro-raman characterization of the lapeyreite mineral, the Alpes-Maritimes region, Nice, France Abstract: The Raman spectroscopy is performed for the first time on the new discovered secondary copper arsenate mineral, lapeyreite [Cu3O[AsO3(OH)]2.0.75H2O]. The bands attributed to two main vibrating (CuO5 and AsO4) units are readily identified in the Raman spectrum. Symmetric stretching modes at 1047 cm-1 and at 627 and 405 cm-1 are assigned to (n1)CuO5, (n2)AsO4 and (n3)AsO4 units, respectively. Bending vibration modes in the Raman spectrum are assigned to (n2)AsO4 units at 214, 198 and 188 cm-1 and to (n2)CuO5 units at 141 and 100 cm-1. In addition, As-O bond and O-H-O bond lengths in the structure of lapeyreite were assigned from the FT-IR at 3420, 2870 and 1640 cm-1. The position and the intensity of both Raman vibrations reveal that the secondary occurring lapeyreite mineral is hydrothermally altered from the primary occurring cuprite mineral.",
Arsenic,1936088,"Trace metals associated with deep-sea tailings placement at the Batu Hijau copper-gold mine, Sumbawa, Indonesia Abstract: The Batu Hijau copper-gold mine on the island of Sumbawa, Indonesia operates a deep-sea tailings placement (DSTP) facility to dispose of the tailings within the offshore Senunu Canyon. The concentrations of trace metals in tailings, waters, and sediments from locations in the vicinity of the DSTP were determined during surveys in 2004 and 2009. In coastal and deep seawater samples from Alas Strait and the South Coast of Sumbawa, the dissolved concentrations of Ag, As, Cd, Cr, Hg, Pb and Zn were in the sub ?g/L range. Dissolved copper concentrations ranged from 0.05 to 0.65?g/L for all depths at these sites. Dissolved copper concentrations were the highest in the bottom-water from within the tailings plume inside Senunu Canyon, with up to 6.5?g Cu/L measured in close proximity to the tailings discharge. In general, the concentrations of dissolved and particulate metals were similar in 2004 and 2009.",
Arsenic,627558,"Arsenic in drinking-water and risk for cancer in Denmark Abstract: BACKGROUND: Arsenic is a well-known carcinogen, which is often found in drinking-water. Epidemiologic studies have shown increased cancer risks among individuals exposed to high concentrations of arsenic in drinking-water, whereas studies of the carcinogenic effect of low doses have had inconsistent results. OBJECTIVE: Our aim was to determine if exposure to low levels of arsenic in drinking-water in Denmark is associated with an increased risk for cancer. METHODS: The study was based on a prospective Danish cohort of 57,053 persons in the Copenhagen and Aarhus areas. Cancer cases were identified in the Danish Cancer Registry, and the Danish civil registration system was used to trace and geocode residential addresses of the cohort members. We used a geographic information system to link addresses with water supply areas, then estimated individual exposure to arsenic using residential addresses back to 1970. Average exposure for the cohort ranged between 0.05 and 25.3 microg/L (mean = 1.2 microg/L). Cox's regression models were used to analyze possible relationships between arsenic and cancer. RESULTS: We found no significant association between exposure to arsenic and risk for cancers of the lung, bladder, liver, kidney, prostate, or colorectum, or melanoma skin cancer; however, the risk for non-melanoma skin cancer decreased with increasing exposure (incidence rate ratio = 0.88/microg/L average exposure; 95% confidence interval, 0.84-0.94). Results adjusted for enrollment area showed no association with non-melanoma skin cancer. CONCLUSIONS: The results indicate that exposure to low doses of arsenic might be associated with a reduced risk for skin cancer.",
Arsenic,1704088,"The application of lithogeochemical and alteration index for copper mineralization in the Sonajil area, NW Iran Abstract: ",
Arsenic,1509339,"Protein tyrosine phosphatases - from housekeeping enzymes to master regulators of signal transduction Abstract: There are many misconceptions surrounding the roles of protein phosphatases in the regulation of signal transduction, perhaps the most damaging of which is the erroneous view that these enzymes exert their effects merely as constitutively active housekeeping enzymes. On the contrary, the phosphatases are critical, specific regulators of signalling in their own right and serve an essential function, in a coordinated manner with the kinases, to determine the response to a physiological stimulus. This review is a personal perspective on the development of our understanding of the protein tyrosine phosphatase family of enzymes. I have discussed various aspects of the structure, regulation and function of the protein tyrosine phosphatase family, which I hope will illustrate the fundamental importance of these enzymes in the control of signal transduction.",
Arsenic,627661,"Risk of arsenic-related skin lesions in Bangladeshi villages at relatively low exposure: A report from Gonoshasthaya Kendra Abstract: OBJECTIVE: Arsenic concentrations in 25% of tube wells in Bangladesh exceed 50 microg/L, a level known to be hazardous. Levels in individual wells vary widely. We gathered data on arsenic exposure levels and skin lesion prevalence to address the lack of knowledge about risks where the average arsenic concentrations was lower. METHODS: The nongovernmental organization Gonoshasthaya Kendra did three related studies of keratotic skin lesions since 2004: (1) an ecological prevalence survey among 13 705 women aged > 18 in a random sample of 53 villages; (2) a case-control study of 176 cases and age- and village-matched referents; and (3) a prevalence survey of the entire population of 11,670 in two additional villages. We calculated prevalence as a function of average arsenic concentrations as reported in the National Hydrochemical Survey, and measured arsenic concentrations in wells used by subjects in the case-control study. FINDINGS: The prevalence of skin lesions was 0.37% in people exposed to arsenic concentrations below 5 microg/L, 0.63% at 6-50 microg/L, and 6.84% at 81 microg/L. In the case-control analysis, relative risk of skin lesions increased threefold at concentrations above 50 microg/L (P < 0.05). CONCLUSION: Little serious skin disease is likely to occur if the arsenic concentration in drinking water is kept below 50 microg/L, but ensuring this water quality will require systematic surveillance and reliable testing of all wells, which may be impractical. More research is needed on feasible prevention of toxic effects from arsenic exposure in Bangladesh.",
Arsenic,1251017,"Effects of arsenite stress on growth and proteome of Klebsiella pneumoniae Abstract: In the present study an arsenite, As(III), tolerating bacterium, MR4, was isolated from Mulla River Pune, India, capable of reducing arsenate to arsenite and identified as Klebsiella pneumoniae (HQ857583). Comparative proteomic analysis using two-dimensional gel electrophoresis (2-DGE) and matrix assisted laser desorption ionization-time of flight-time of flight (MALDI-TOF/TOF) was used to monitor the proteins undergoing changes in expression levels under 2.5 mM As(III) stress. The 2-DGE proteome map has shown that 60 proteins were differentially expressed under As(III) stress, of which 39 proteins were successfully identified with a MASCOT score greater than 70 (p&lt;0.05). Among the identified proteins, membrane transport/binding proteins, porins, and amino acid metabolism enzymes were down-regulated while stress responsive proteins and antioxidant enzymes were up-regulated. Proteins involved in carbohydrate metabolism, particularly those in pentose phosphate pathway were also up-regulated while those involved in pyruvate metabolism were down-regulated. However, proteins involved in glycolysis and tricarboxylic acid cycle showed a mixed regulation response. These findings provide new insights into the probable mechanisms by which K. pneumoniae (HQ857583) could be adapting to As(III) stress.",
Arsenic,1509346,Assay of Biochemical Compositions of Two Indian Fresh Water Eel with Special Emphasis on Accumulation of Toxic Heavy Metals Abstract: ,
Arsenic,2343545,"Manganese-reducing Pseudomonas fluorescens-group bacteria control arsenic mobility in gold mining-contaminated groundwater Abstract: Previous studies show the importance of iron- and arsenate-reducing bacteria in mobilizing arsenic in groundwater. Here the authors present experimental evidence of arsenic mobilization in connection with bacterially mediated manganese reduction in groundwater affected by mining activities. Manganese-reducing Pseudomonas species were enriched, isolated and identified by 16S rRNA gene phylogeny from groundwater containing high co-dissolved arsenic (as As-III) and manganese. Enrichment cultures dissolved synthetic birnessite and hausmannite efficiently, but Mn reduction by isolates was reduced at the upper range of environmental levels of dissolved As-III. Results suggest either a self-limiting release of arsenic coupled to bacterial manganese reduction, in the absence of other electron donors like sulfide, or increased arsenic resistance conferred to Mn-reducing bacteria in consortia.",
Arsenic,491767,"In utero and postnatal exposure to arsenic alters pulmonary structure and function Abstract: in addition to cancer endpoints, arsenic exposures can also lead to non-cancerous chronic lung disease. Exposures during sensitive developmental time points can contribute to the adult disease. Using a mouse model, in utero and early postnatal exposures to arsenic (100 ppb or less in drinking water) were found to alter airway reactivity to methacholine challenge in 28 day old pups. Removal of mice from arsenic exposure 28 days after birth did not reverse the alterations in sensitivity to methacholine. In addition, adult mice exposed to similar levels of arsenic in drinking water did not show alterations. Therefore, alterations in airway reactivity were irreversible and specific to exposures during lung development. These functional changes correlated with protein and gene expression changes as well as morphological structural changes around the airways. Arsenic increased the whole lung levels of smooth muscle actin in a dose dependent manner. The level of smooth muscle mass around airways was increased with arsenic exposure, especially around airways smaller than 100 mu m in diameter. This increase in smooth muscle was associated with alterations in extracellular matrix (collagen, elastin) expression. This model system demonstrates that in utero and postnatal exposure to environmentally relevant levels of arsenic can irreversibly alter Pulmonary structure and function in the adults. (C) 2008 Elsevier Inc. All rights reserved.",
Arsenic,1026559,"Protection of arsenic-induced hepatic disorder by arjunolic acid Abstract: Arsenic is one of the ubiquitous environmental pollutants, which affects nearly all organ systems. The present study has been carried out to investigate the hepatoprotective role of arjunolic acid, a triterpenoid saponin, against arsenic-induced oxidative damages in murine livers. Administration of sodium arsenite at a dose of 10 mg/kg body weight for 2 days significantly reduced the activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione S-transferase, glutathione reductase and glutathione peroxidase as well as depleted the level of reduced glutathione and total thiols. In addition, sodium arsenite also increased the activities of serum marker enzymes, alanine transaminase and alkaline phosphatase, enhanced DNA fragmentation, protein carbonyl content, lipid peroxidation end-products and the level of oxidized glutathione. Studies with arjunolic acid show that in vitro it possesses free radical-scavenging and in vivo antioxidant activities. Treatment with arjunolic acid at a dose of 20 mg/kg body weight for 4 days prior to arsenic administration prevents the alterations of the activities of all antioxidant indices and levels of the other parameters studied. Histological studies revealed less centrilobular necrosis in the liver treated with arjunolic acid prior to arsenic intoxication compared to the liver treated with the toxin alone. Effects of a known antioxidant, vitamin C, have been included in the study as a positive control. In conclusion, the results suggest that arjunolic acid possesses the ability to attenuate arsenic-induced oxidative stress in murine liver probably via its antioxidant activity.",
Arsenic,1025419,"Mechanism of arsenic-induced neurotoxicity may be explained through cleavage of p35 to p25 by calpain Abstract: In recent studies we have demonstrated that arsenic (As) metabolites change the composition of neuronal cytoskeletal proteins in vivo and in vitro. To further examine the mechanism of arsenic-induced neurotoxicity with various arsenate metabolites (iAsV, MMAV and DMAV) and arsenite metabolites (iAsIII, MMAIII and DMAIII), we investigated the role of the proteolytic enzyme calpain and its involvement in the cleavage of p35 protein to p25, and also mRNA expression levels of calpain, cyclin-dependent kinase 5 (cdk5) and glycogen synthase kinase 3 beta (gsk3ss). A HeLa cell line transfected with a p35 construct (HeLa-p35) was used as a model, since all other proteins such as calpain, CDK5 and GSK3beta are already present in HeLa cells as they are in neuronal cells. HeLa-p35 cells were incubated with various As metabolites and concentrations of 0, 10 and 30 microM for duration of 4 h. Subsequently the cells were either lysed to study their relative quantification levels of these genes or to be examined on their p35-protein expression. P35-RNA expression levels were significantly (p&lt;0.01) increased by arsenite metabolites, while p35 protein was cleaved to p25 (and p10) after incubation with these metabolites. The cleavage of p35 is caused by calcium (Ca2+) induced activation of calpain. Inhibition of calpain activity by calpeptin prevents cleavage of p35 to p25. These results suggest that cleavage of p35 to p25 by calpain, probably As-induced Ca2+-influx, may explain the mechanism by which arsenic induces its neurotoxic effects.",
Arsenic,1508615,"Ets1 and heat shock factor 1 regulate transcription of the Transformer 2? gene in human colon cancer cells Abstract: BACKGROUND: Transformer (Tra) 2? is a member of the serine/arginine-rich (SR)-like protein family that regulates alternative splicing of numerous genes in a concentration-dependent manner. Several types of cancer cells up-regulate Tra2? expression, while the regulatory mechanism of Tra2? expression remains to be elucidated. In this study, we examined the transcriptional regulation and possible functions of Tra2? in human colon cancer cells. METHODS: We cloned 959 bp-upstream of the human TRA2? 5'-flank into luciferase constructs. Chromatin immunoprecipitation (ChIP) was employed to identify crucial cis element(s) and trans activator(s) of the TRA2? promoter. Tra2? expression in the human colon and colon cancer tissues was examined by immunohistochemistry. RESULTS: In response to sodium arsenite, colon cancer cells (HCT116) increased levels of TRA2?1 mRNA encoding a functional, full-length Tra2? with a peak around 6 h without changing its mRNA stability. Transient expression assays using a reporter gene driven by serially truncated TRA2? promoters and Chip assay demonstrated that an Ets1-binding site present at -64 to -55 bp was crucial for basal transcription, while three heat shock elements (HSEs) located at -145 to -99 bp mediated the oxidant-induced transactivation of TRA2?. Tra2? knockdown caused apoptosis of HCT116 cells. Tra2? were preferentially expressed in proliferative compartment of normal human colonic glands and adenocarcinomas, where Ets1 and heat shock factor 1 were also highly expressed. CONCLUSIONS: Our results suggest that oxidative stress-responsive Tra2? may play an important role in colon cancer growth.",
Arsenic,1255509,"Arsenic urinary concentrations in children living in a naturally arsenic contaminated area Abstract: A cross sectional study using environmental and biological samples was undertaken to assess the association between arsenic (As) soil concentrations and urinary As levels of children living in an area where the soil is naturally As rich, during summer and winter. Twenty-nine children aged between 2 and 7 years from 21 dwellings in the summer study, and 23 of the 29 previous children from 17 dwellings in the winter study, were recruited. Housing characteristics, living conditions and individual characteristics were collected by questionnaire, and urine samples were collected for iAs+MMA+DMA measurement. Soil total As content and bioaccessibility were measured. Urinary As concentrations revealed that the children were not overexposed. Low bioaccessibility combined with moderately high levels in soil could explain this result. The concentration of arsenic in soil and soil-related factors appeared to contribute to the children's impregnation in summer but not in winter, which could be related to the children's behavior. This study highlights the need for additional studies of children to better understand their behavior, and obtain reference values in this particular population.Journal of Exposure Science and Environmental Epidemiology advance online publication, 18 July 2012; doi:10.1038/jes.2012.72.",
Arsenic,1508588,"Expression of a rice Lambda class of glutathione S-transferase, OsGSTL2, in Arabidopsis provides tolerance to heavy metal and other abiotic stresses Abstract: Global industrial growth has contaminated the soil and water with many hazardous compounds, including heavy metals. These heavy metals are not only toxic to plants but also cause severe human health hazards when leach out into food chain. One of the approaches employed for the decontamination of environment includes identification and overexpression of genes involved in the detoxification mechanism of plants. Glutathione S-transferases (GSTs) are a superfamily of enzymes, principally known for their role in detoxification reactions. Different classes of GSTs have been used to develop plants with improved detoxification mechanism, but not much information is available for Lambda class of GSTs. Here, we studied expression of OsGSTLs in different rice genotypes under arsenic stress. The study suggests differential expression of these genes in arsenic sensitive and tolerant genotypes. Further, the role of one member of Lambda class OsGSTL2 was studied by expressing in heterologous system, Arabidopsis. Transgenic lines developed were analysed for their response to different abiotic stresses including heavy metals. Analysis suggests that OsGSTL2 provides tolerance for heavy metals and other abiotic stresses like cold, osmotic stress and salt. We conclude that OsGSTLs can be utilized for developing plant varieties tolerant to different abiotic stresses including heavy metals.",
Arsenic,2337220,"Effect of ultrasonic treatment on heavy metal decontamination in milk Abstract: Ultrasound has been found useful in increasing the efficiency and consumer safety in food processing. Removal of heavy metal (lead, mercury, and arsenic) contamination in milk is extremely important in regions of poor ecological environment - urban areas with heavy motor traffic or well established metallurgical/cement industry. In this communication, we report on the preliminary studies on the application of low frequency (20kHz) ultrasound for heavy metal decontamination of milk without affecting its physical, chemical, and microbiological properties.",
Arsenic,627899,"A retrospective study on malignant neoplasms of bladder, lung and liver in blackfoot disease endemic area in Taiwan Abstract: A total of 69 bladder cancer, 76 lung cancer and 59 liver cancer deceased cases and 368 alive community controls group-matched on age and sex were studied to evaluate the association between high-arsenic artesian well water and cancers in the endemic area of blackfoot disease (BFD), a unique peripheral vascular disease related to continuous arsenic exposure. According to a standardized structured questionnaire, information on risk factors was obtained through proxy interview of the cases and personal interview of the controls. A positive dose-response relationship was observed between the exposure to artesian well water and cancers of bladder, lung and liver. The age-sex-adjusted odds ratios of developing bladder, lung and liver cancers for those who had used artesian well water for 40 or more years were 3.90, 3.39, and 2.67, respectively, as compared with those who never used artesian well water. Multiple binary logistic regression analyses showed that the dose-response relationships and odds ratios remained much the same while other risk factors were further adjusted.",
Arsenic,129101,"Drinking water arsenic exposure and blood pressure in healthy women of reproductive age in Inner Mongolia, China Abstract: The extremely high exposure levels evaluated in prior investigations relating elevated levels of drinking water arsenic and hypertension prevalence make extrapolation to potential vascular effects at lower exposure levels very difficult. A cross-sectional study was conducted on 8790 women who had recently been pregnant in an area of Inner Mongolia, China known to have a gradient of drinking water arsenic exposure. This study observed increased systolic blood pressure levels with increasing drinking water arsenic, at lower exposure levels than previously reported in the literature. As compared to the referent category (below limit of detection to 20 ?g of As/L), the overall population mean systolic blood pressure rose 1.29 mm Hg (95% CI 0.82, 1.75), 1.28 mm Hg (95% CI 0.49, 2.07), and 2.22 mm Hg (95% CI 1.46, 2.97) as drinking water arsenic concentration increased from 21 to 50, 51 to 100, and > 100 ?g of As/L, respectively. Controlling for age and body weight (n = 3260), the population mean systolic blood pressure rose 1.88 mm Hg (95% CI 1.03, 2.73), 3.90 mm Hg (95% CI 2.52, 5.29), and 6.83 mm Hg (95% CI 5.39, 8.27) as drinking water arsenic concentration increased, respectively. For diastolic blood pressure effect, while statistically significant, was not as pronounced as systolic blood pressure. Mean diastolic blood pressure rose 0.78 mm Hg (95% CI 0.39, 1.16), 1.57 mm Hg (95% CI 0.91, 2.22) and 1.32 mm Hg (95% CI 0.70, 1.95), respectively, for the overall population and rose 2.11 mm Hg (95% CI 1.38, 2.84), 2.74 mm Hg (95% CI 1.55, 3.93), and 3.08 mm Hg (95% CI 1.84, 4.31), respectively, for the adjusted population (n = 3260) at drinking water arsenic concentrations of 21 to 50, 51 to 100, and > 100 ?g of As/L. If our study results are confirmed in other populations, the potential burden of cardiovascular disease attributable to drinking water arsenic is significant.",
Arsenic,1337335,"Cultivar-specific kinetics of chitinase induction in soybean roots during exposure to arsenic Abstract: The kinetics of defense responses was studied in soybean exposed to ecologically relevant concentrations of arsenic for 96 h. In the roots of two soybean cultivars with contrasting tolerance to this metalloid there were observed differences in basal levels of membrane lipid peroxidation as well as a significantly different course of peroxidation upon exposure to As. The different course of stress was reflected in the accumulation of defense components. The responses of individual chitinase isoforms were studied since these enzymes had previously been shown to be stable components of defense against metals. The kinetics and magnitude of accumulation of the three isoforms during exposure to As significantly differed within as well as between the studied cultivars. Furthermore, accumulation of these isoforms appeared to be related to oxidative status in the root tissue. The timing of induced responses is likely to be important for efficient defense against metal(oid) pollution in environment.",
Arsenic,1031830,"Arsenite inhibits two steps in the ubiquitin-dependent proteolytic pathway Abstract: Eukaryotic cells possess a multienzyme ATP-dependent proteolytic pathway in which the small, highly conserved protein ubiquitin (Ub) acts as a cofactor. In this pathway, formation of a covalent Ub-substrate conjugate precedes ATP-dependent degradation of the substrate. Inorganic arsenite (AsO2-) inhibited Ub-dependent protein degradation in a concentration-dependent fashion, both in intact rabbit reticulocytes and in a reticulocyte lysate (fraction II). Concentrations of arsenite causing half-maximal inhibition in fraction II varied with the substrate, ranging from 0.025 mM (bovine alpha-lactalbumin) to 3.3 mM (reduced/carboxymethylated bovine serum albumin). Inhibition was rapidly reversed upon addition of dithiothreitol. Arsenite inhibited the Ub-dependent proteolytic pathway at one or both of two steps, depending on the substrate. 1) Proteins with acidic amino termini must be amino terminally arginylated, in a tRNA-dependent reaction, prior to becoming conjugated to Ub (Ferber, S., and Ciechanover, A. (1987) Nature 326, 808-811). Arsenite inhibited substrate arginylation, and therefore also inhibited Ub conjugation. The inhibited species appeared to be arginyl aminoacyl-tRNA transferase, since arsenite was without strong effect on the rate or extent of arginyl-tRNA formation in fraction II, yet almost completely inhibited arginine transfer from arginyl-tRNA to reduced/carboxymethylated bovine serum albumin. 2) Arsenite also inhibited Ub-substrate conjugate turnover, as shown in pulse-chase experiments. For a given substrate, degradative (protease-dependent) and Ub regenerative (isopeptidase-dependent) components of conjugate turnover were similarly inhibited by arsenite. The potency of this inhibition varied for different substrates. Monosubstituted trivalent arsenicals such as arsenite typically interact with sites containing vicinal sulfhydryl groups. Inhibition by arsenite of two steps in the Ub-dependent proteolytic pathway suggests that the relevant pathway components could possess this kind of structural/catalytic feature.",
Arsenic,2279281,"Draft genome sequence of the polyextremophilic Halorubrum sp. strain AJ67, isolated from hyperarsenic lakes in the Argentinian Puna Abstract: Halorubrum sp. strain AJ67, an extreme halophilic UV-resistant archaeon, was isolated from Laguna Antofalla in the Argentinian Puna. The draft genome sequence suggests the presence of potent enzyme candidates that are essential for survival under multiple environmental extreme conditions, such as high UV radiation, elevated salinity, and the presence of critical arsenic concentrations.",
Arsenic,1677554,"Arsenic exposure from drinking water, arsenic methylation capacity, and carotid intima-media thickness in Bangladesh Abstract: We conducted a cross-sectional study to evaluate the interrelationships between past arsenic exposure, biomarkers specific for susceptibility to arsenic exposure, and carotid intima-media thickness (cIMT) in 959 subjects from the Health Effects of Arsenic Longitudinal Study in Bangladesh. We measured cIMT levels on average 7.2 years after baseline during 2010-2011. Arsenic exposure was measured in well water at baseline and in urine samples collected at baseline and during follow-up. Every 1-standard-deviation increase in urinary arsenic (357.9 µg/g creatinine) and well-water arsenic (102.0 µg/L) concentration was related to a 11.7-µm (95% confidence interval (CI): 1.8, 21.6) and 5.1-µm (95% CI: -0.2, 10.3) increase in cIMT, respectively. For every 10% increase in monomethylarsonic acid (MMA) percentage, there was an increase of 12.1 µm (95% CI: 0.4, 23.8) in cIMT. Among participants with a higher urinary MMA percentage, a higher ratio of urinary MMA to inorganic arsenic, and a lower ratio of dimethylarsinic acid to MMA, the association between well-water arsenic and cIMT was stronger. The findings indicate an effect of past long-term arsenic exposure on cIMT, which may be potentiated by suboptimal or incomplete arsenic methylation capacity. Future prospective studies are needed to confirm the association between arsenic methylation capacity and atherosclerosis-related outcomes.",
Arsenic,2088353,Sensitive colorimetric detection of melamine in milk with an aptamer-modified nanogold probe Abstract: ,
Arsenic,1380908,"Phenylarsine oxide (PAO) blocks antigen receptor-induced calcium response and tyrosine phosphorylation of a distinct group of proteins Abstract: Antigen receptor (AgR) crosslinking by antigens or AgR-specific antibodies induces a cascade of enzymatic events in lymphocytes which involves activation of several non-receptor tyrosine- and serine/threonine kinases, phosphatases, phospholipases, etc. Here we show data demonstrating that a thiol group-reactive protein tyrosine phosphatase (PTP) inhibitor, phenylarsine oxide (PAO), uncouples a crucial part of the signaling events induced by anti-IgM or anti-Leu-4 (CD3) in human tonsil B lymphocytes, BL41 and Daudi B cell lines and Jurkat T lymphoma cells. PAO treatment (10 microM) resulting in distinct modification of AgR-induced tyrosine phosphorylation pattern inhibited the AgR-mediated calcium response (Ca++ release and influx) of all of these cells completely. Since this treatment did not alter the cell viability and the binding capacity of the AgR crosslinking antibodies, alteration of the tyrosine phosphorylation pattern and blockage of the calcium response indicate prompt inactivation of essential signal transduction element(s).",
Arsenic,1597375,"Ultrasound as a useful tool in the diagnosis and management of traumatic nerve lesions Abstract: <strong>OBJECTIVE: </strong>The possibility of depicting through ultrasound (US) the nerve and its surroundings should be very useful in traumatic nerve lesion (TNL) management. Our study aimed at evaluating the contribution of US as complementary tool in a neurophysiological laboratory for the diagnosis and management of TNL.<br /><br /><strong>METHODS: </strong>A total of 112 nerves from 98 consecutive patients with clinical suspicion of TNL were considered. Two independent and blinded clinicians, different from the examiners performing electrodiagnosis and US, classified clinical, neurophysiological and US findings and classified the contribution of US as follows: 'contributive' and 'non-contributive' if US confirmed the clinical and neurophysiological diagnosis or if US findings were unremarkable.<br /><br /><strong>RESULTS: </strong>US was 'contributive' (strongly modified the diagnostic and therapeutic path) in 58% of cases (n: 65) providing information on therapeutic approach (immediate or delayed surgery), diagnosis and follow-up. US specifically contributed to the (1) assessment of nerve continuity/discontinuity, hence neurotmesis/axonotmesis; (2) identification of aetiology; and (3) demonstration of multiple sites of damage. US was contributive mainly in cases with neurophysiological evidence of complete axonal damage.<br /><br /><strong>CONCLUSIONS: </strong>US should be used, when available, in all patients in whom TNL is suspected as it provides a more comprehensive diagnosis than neurophysiologic studies alone. Anatomical information is often crucial for choosing the most appropriate therapeutic strategies (and for surgical planning).<br /><br /><strong>SIGNIFICANCE: </strong>US can improve the outcome of TNL.",
Arsenic,2343516,"Occupational exposure to solid chemical agents in biomass-fired power plants and associated health effects Abstract: Occupational exposure to aluminium, arsenic, lead, cadmium, and manganese can increase the risk of numerous neurophysiological changes in workers, and may lead to conditions resembling Parkinson's and Alzheimer's disease. However, although the health hazard aspect of these agents has been examined, biomass-fired power plant workers' exposure to them remains a neglected issue. The purpose of this study was to measure maintenance and ash removal workers' multiple exposures to inhalable dust, metals, and crystalline silica during their work tasks in biomass-fired power plants. Maintenance and ash removal workers were exposed to high inhalable dust concentrations inside biomass-fired boilers. The median air inhalable dust concentration in workers' breathing zones were 33 mg m(-3) and 120 mg m(-3) in ash removal and maintenance tasks, respectively. The median concentration of manganese (0.31 mg m(-3)) exceeded the occupational exposure limit in worker's breathing zone samples in maintenance tasks. The most evident exposure-associated health risk from multiple exposures to metals was that of cancer, followed by central nervous system disorders, lower respiratory tract irritation, and finally upper respiratory tract irritation. To avoid the above mentioned health effects, powered air respirators with ABEK+P3 cartridges and carbon monoxide gas detectors are recommended as the minimum requirement for these work tasks. A compressed air breathing apparatus is the best form of protection for the most demanding work phases inside boilers in biomass-fired power plants.",
Arsenic,628404,"Enzymatic methylation of arsenic compounds: Assay, partial purification, and properties of arsenite methyltransferase and monomethylarsonic acid methyltransferase of rabbit liver Abstract: A rapid, accurate, in vitro assay utilizing radioactive S-adenosylmethionine (SAM) has been developed for the methylation of arsenite and monomethylarsonate (MMA) by rabbit liver methyltransferases. The assay has been validated by separating, identifying, and measuring the products of the reaction using chloroform extraction, ion exchange chromatography, TLC, or HPLC. The enzymes involved in this pathway, arsenite methyltransferase and MMA methyltransferase, have been purified approximately 2000-fold from rabbit liver. After gel electrophoresis, a single band is obtained with both enzyme activities in it. The pH optima for purified arsenite methyltransferase and monomethylarsonic acid methyltransferase are 8.2 and 8.0, respectively. A thiol, S-adenosylmethionine, and arsenite are required for the partially purified arsenite methyltransferase that catalyzes the synthesis of monomethylarsonate. A different enzyme activity that catalyzes the methylation of monomethylarsonate to dimethylarsinate also requires SAM and a thiol. Even though arsenite methyltransferase and monomethylarsonate methyltransferase have different substrates, pH optima, and saturation concentrations for their substrates, whether the two activities are present on one protein molecule or different protein molecules is still uncertain. Both activities have a molecular mass of 60 kDa as determined by gel exclusion chromatography. There is no evidence at the present time for these enzyme activities being on different protein molecules. Neither arsenate, selenate, selenite, or selenide are methylated by the purified enzyme preparations. Results from the use of crude extracts, often called cytosol, to study the properties of these methyltransferases dealing with arsenic species should be viewed with caution since such crude extracts contain inhibiting and other interfering activities.",
Arsenic,628420,"Chromosome studies in human subjects chronically exposed to arsenic in drinking water Abstract: A two-year study was carried out on human subjects of various ages and backgrounds who had been drinking water containing more than 0.05 mg/liter (0.05 ppm) arsenic for a period of at least five years. The main aim was to correlate the frequency of chromosome aberrations and sister chromatid exchanges in the lymphocytes with the amount of arsenic in the water. In addition, we explored the incidence of skin cancer, fetal wastage, and genetic or developmental abnormalities. Several other variables--eg, coffee, wine, and cigarette consumption; sex; residence (rural vs urban); and exposure to chemicals, smelters, or pesticides--were also taken into consideration. The data on chromosome aberrations (104 exposed and 86 control individuals) and on sister chromatid exchanges (98 exposed and 83 control individuals) did not show that arsenic at concentrations used by our population (greater than 0.05 mg/liter) has any effect on these parameters. Similarly, no other health effects of arsenic at these concentrations were found.",
Arsenic,1030375,"Trace elements in hair of Blackfoot disease Abstract: Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Though extensive epidemiological study has implicated that high arsenic content in artesian well water of the endemic area bears some important connection with the disease, the etiology of the disease is still unknown. In this study, attention is paid to multielement determination in order to find out whether the trace elements in hair of Blackfoot disease patients are different from those of the controls. Experimental results indicate that the concentrations of As and Se in hair of patients are significantly higher than those of the controls, but Ca and Zn are significantly lower than those of the controls. The possible connection of these elements with the etiology of the disease is discussed.",
Arsenic,2343461,"Role of nanoparticles in controlling arsenic mobilization from sediments near a realgar tailing Abstract: Microcosm experiments were conducted to investigate the mechanism of microbial-mediated As mobilization from high arsenic tailing sediments amended with nanoparticles (NPs). The addition of SiO2 NPs could substantially stimulate arsenic mobilization in the sodium acetate amendment sediments. However, the addition of Fe2O3 and Fe3O4 NPs restrained arsenic release because these NPs resulted in Fe-As coprecipiate. Moreover, NP additions in sediments amended with sodium acetate as the electron donor clearly promoted microbial dissimilatory iron reduction. Nearly 4 times the Fe(II) (11.67-12.87 mg•L-1) from sediments amended with NPs and sodium acetate was released compared to sediments amended with only sodium acetate (3.49 mg•L-1). Based on molecular fingerprinting and sequencing analyses, the NP additions could potentially change the sediment bacterial community composition and increase the abundance of Fe(III) and As(V) reduction bacteria. Several potential NP-stimulated bacteria were related to Geobacter, Anaeromyxobacter, Clostridium and Alicyclobacillus. The findings offer a relatively comprehensive assessment of NP (e.g., Fe2O3, Fe3O4 and SiO2) effects on sediment bacterial communities and As mobilization.",
Arsenic,710858,"Arsenite induces endothelial cell permeability increase through a reactive oxygen species--Vascular endothelial growth factor pathway Abstract: As a potent environmental oxidative stressor, arsenic exposure has been reported to exacerbate cardiovascular diseases and increase vascular endothelial cell monolayer permeability. However, the underlying mechanism of this effect is not well understood. In this paper, we test our hypothesis that reactive oxygen species (ROS)-induced vascular endothelial growth factor (VEGF) expression may play an important role in an arsenic-caused increase of endothelial cell monolayer permeability. The mouse brain vascular endothelial cell bEnd3 monolayer was exposed to arsenite for 1, 3, and 6 days. The monolayer permeability, VEGF protein release, and ROS generation were determined. In addition, VE-cadherin and zonula occludens-1 (ZO-1), two membrane structure proteins, were immunostained to elucidate the effects of arsenite on the cell-cell junction. The roles of ROS and VEGF in arsenite-induced permeability was determined by inhibiting ROS with antioxidants and immuno-depleting VEGF with a VEGF antibody. We observed that arsenite increased bEnd3 monolayer permeability, elevated the production of cellular ROS, and increased VEGF release. VE-cadherin and ZO-1 disruptions were also found in cells treated with arsenite. Furthermore, both antioxidant (N-acetyl cysteine and tempol) and the VEGF antibody treatments significantly lowered the arsenite-induced permeability of the bEnd3 monolayer as well as VEGF expression. VE-cadherin and ZO-1 disruptions were also diminished by N-acetyl cysteine and the VEGF antibody. Our data suggest that the increase in VEGF expression caused by ROS may play an important role in the arsenite-induced increase in endothelial cell permeability.",
Arsenic,1030955,"Mechanism of arsenic-induced inhibition of erythropoiesis in mice Abstract: Anemia accompanies arsenic intoxication in man. The present studies were undertaken to clarify further the effects of arsenic on erythropoiesis. A dose-related inhibition of red cell 59 Fe incorporation and reticulocyte response was observed in normal mice treated with a single injection of arsenic. Arsenite was approximately two times as inhibitory as arsenate. The effects of arsenic on erythropoietin-induced erythroid differentation revealed a significant inhibitory effect on young, proliferating marrow nucleated erythroid precursor cells. More mature, nonproliferating nucleated erythr oid cells were resistant to the toxic action of arsenic. A dose-related inhibitory effect of arsenic on DNA synthesis was observed in fetal liver nucleated erythroid cells incubated with 3 H thymidine. Ineffective erythropoiesis as well as the megaloblastic morphology accompanying aberrant DNA synthesis -- manifestations of arsenic toxicity in man -- were not evident in the present studies.",
Arsenic,1070325,"Determination of zeta potential in Planctomycetes and its application in heavy metals toxicity assessment Abstract: Zeta potential of Planctomycetes was evaluated under different environmental conditions and correlated to cell viability. Phylogenetically distinct strains of the Planctomycetes presented different negative zeta potential values. More negative values were associated with Rhodopirellula spp. and related to the great amount of fimbriae in these species. Milli-Q water was chosen as the best dispersion media to perform the measurements. Zeta potential increased with ionic strength and varied with pH. In the physiological range of pH 5.0-9, zeta potential remained low and Rhodopirellula sp. strain LF2 cells were viable. Out of this range, zeta potential increased significantly and viability decreased. The effect on zeta potential of arsenic, cadmium, chromium, copper, lead, nickel, and zinc was assessed in Rhodopirellula sp. strain LF2. Zeta potential increased with increasing toxicity of the heavy metals in a dose-response way. This result was confirmed by the results observed for Rhodopirellula baltica strain SH1 under copper toxicity. Lead was the most toxic metal and zinc was the least toxic as observed by zeta potential and viability. The results support a correlation between zeta potential and cell viability which seem to indicate the possibility to use it as a viability predictor for the effects of heavy metals toxicity.",
Arsenic,589077,"Comparative toxicity of arsenite metabolites in wild type cho cells and in cells deficient in excision repair cross-complementing 1 and 2 Abstract: Arsenic (As) has been shown to alter one or more DNA repair processes. Excision repair cross-complementing 1 and 2 (ERCC1 and ERCC2) have shown to be associated with arsenic-induced toxicity and carcinogenicity. In this study, we investigated cytotoxic effects of various As metabolites in relation to two nucleotide excision repair genes: ERCC1 and ERCC2. Various arsenate (pentavalent) and arsenite (trivalent) metabolites were tested in ERCC1, ERCC2 deficient and wild type cells. Our results showed that in the selected concentration range pentavalent As metabolites; iAsV, MMAV and DMAV were not cytotoxic, unlike the trivalent As metabolites; iAsIII, MMAIII and DMAIII. The measured LC50 demonstrated a significant difference (pÂ <Â 0.01) for iAsIII between the three cell lines, while MMAIII and DMAIII are more cytotoxic to all three cell lines. UV5 (ERCC2 deficient) cells also showed a lower resistance to iAsIII in comparison to AA8 (wild type) and UV20 (ERCC2 deficient) cells. This might be explained through the generation of hydrogen peroxide (H2O2), which is generated by increase of intracellular Ca2+ level. Generation of H2O2 in UV5 cells after incubation with iAsIII is significantly higher than AA8 and UV20 cells (pÂ <Â 0.01). In conclusion, absence of ERCC2 leads to a increased generation of H2O2 by iAsIII in UV5 cells, which is in contrast to AA8 and UV20 cells.",
Arsenic,1794795,"Legacy of cyanide and ARD at a low-scale gold mine (Furtei, Italy) Abstract: A gold deposit was exploited from 1997 to 2003 at Furtei, Sardinia (Italy). Gold and silver were recovered from oxidized ores by cyanidation; copper concentrates were separated from the sulfide ores by flotation. Following unplanned closure, sulfide-rich materials derived from mining and processing residues were left on site. During operation, cyanide solutions were disposed of in a tailings impoundment. The cyanide underwent natural degradation so that by 2011, cyanide concentrations in the tailings impoundment and seeps were below the Italian limit for industrial effluents. However, during the rainy season, sulfide-rich materials in the waste rock dumps produce extreme acidic solutions and concentrations of some dissolved contaminants, especially ammonium, aluminum, arsenic, copper, iron and manganese, still exceed discharge criteria in the tailings impoundment and seeps. Highly contaminated drainage flows downstream from the mine and poses a hazard to agricultural areas.",
Arsenic,1348191,"p38 alpha and p38 delta mitogen-activated protein kinase isoforms regulate invasion and growth of head and neck squamous carcinoma cells Abstract: Recent studies indicate that the specificity of p38 mitogen-activated protein kinase (MAPK)-mediated cellular stress responses is determined by the expression pattern of the distinct p38 isoforms. Here, we have analysed the function of distinct p38 isoforms in the growth and invasion of head and neck squamous cell carcinomas (HNSCCs). Activation of p38 MAPK by arsenite resulted in inactivation of the ERK1,2 signaling pathway by dephosphorylation of MEK1,2 in primary human epidermal keratinocytes (HEKs), whereas in HNSCC cells this p38-mediated inhibition of the ERK1,2 pathway was absent. Quantitation of p38 pathway component mRNA expression in HNSCC cell lines (n=42) compared to HEKs (n=8) revealed that p38alpha and p38delta isoforms are predominantly expressed in both cell types and that MKK3 is the primary upstream activator expressed. Inhibition of endogenous p38alpha or p38delta activity by adenoviral delivery of corresponding dominant-negative p38 isoforms potently reduced MMP-13 and MMP-1 expressions, and suppressed the invasion of HNSCC cells through collagen. Dominant-negative p38alpha and p38delta inhibited squamous cell carcinoma (SCC) cell proliferation and inhibition of p38alpha activity also compromised survival of SCC cells. p38alpha and p38delta were predominantly expressed in HNSCCs (n=24) and nonneoplastic epithelium in vivo (n=6), with MKK3 being the primary upstream activator. Activation and expression of p38alpha and p38delta by tumor cells was detected in HNSCCs in vivo (n=16). Adenoviral expression of dominant-negative p38alpha or p38delta in cutaneous SCC cells potently inhibited their implantation in skin of severe combined immunodeficiency mice and growth of xenografts in vivo. Our results indicate that p38alpha and p38delta specifically promote the malignant phenotype of SCC cells by regulating cell survival, proliferation and invasion, suggesting these p38 MAPK isoforms as potential therapeutic targets in HNSCCs.",
Arsenic,1579340,"Ribosomal protein S7 regulates arsenite-induced GADD45? expression by attenuating MDM2-mediated GADD45? ubiquitination and degradation Abstract: The stress-responding protein, GADD45?, plays important roles in cell cycle checkpoint, DNA repair and apoptosis. In our recent study, we demonstrate that GADD45? undergoes a dynamic ubiquitination and degradation in vivo, which process can be blocked by the cytotoxic reagent, arsenite, resulting in GADD45? accumulation to activate JNKs cell death pathway, thereby revealing a novel mechanism for the cellular GADD45? functional regulation. But the factors involved in GADD45? stability modulations are unidentified. Here, we demonstrated that MDM2 was an E3 ubiquitin ligase for GADD45?. One of MDM2-binding partner, ribosomal protein S7, interacted with and stabilized GADD45? through preventing the ubiquitination and degradation of GADD45? mediated by MDM2. This novel function of S7 is unrelated to p53 but seems to depend on S7/MDM2 interaction, for the S7 mutant lacking MDM2-binding ability lost its function to stabilize GADD45?. Further investigations indicated that arsenite treatment enhanced S7-MDM2 interaction, resulting in attenuation of MDM2-dependent GADD45? ubiquitination and degradation, thereby leading to GADD45?-dependent cell death pathway activation. Silencing S7 expression suppressed GADD45?-dependent cytotoxicity induced by arsenite. Our findings thus identify a novel function of S7 in control of GADD45? stabilization under both basal and stress conditions and its significance in mediating arsenite-induced cellular stress.",
Arsenic,1070322,"The Pht1;9 and Pht1;8 transporters mediate inorganic phosphate acquisition by the Arabidopsis thaliana root during phosphorus starvation Abstract: • The activation of high-affinity root transport systems is the best-conserved strategy employed by plants to cope with low inorganic phosphate (Pi) availability, a role traditionally assigned to Pi transporters of the Pht1 family, whose respective contributions to Pi acquisition remain unclear. • To characterize the Arabidopsis thaliana Pht1;9 transporter, we combined heterologous functional expression in yeast with expression/subcellular localization studies and reverse genetics approaches in?planta. Double Pht1;9/Pht1;8 silencing lines were also generated to gain insight into the role of the closest Pht1;9 homolog. • Pht1;9 encodes a functional plasma membrane-localized transporter that mediates high-affinity Pi/H(+) symport activity in yeast and is highly induced in Pi-starved Arabidopsis roots. Null pht1;9 alleles exhibit exacerbated responses to prolonged Pi limitation and enhanced tolerance to arsenate exposure, whereas Pht1;9 overexpression induces the opposite phenotypes. Strikingly, Pht1;9/Pht1;8 silencing lines display more pronounced defects than the pht1;9 mutants. • Pi and arsenic plant content analyses confirmed a role of Pht1;9 in Pi acquisition during Pi starvation and arsenate uptake at the root-soil interface. Although not affecting plant internal Pi repartition, Pht1;9 activity influences the overall Arabidopsis Pi status. Finally, our results indicate that both the Pht1;9 and Pht1;8 transporters function in sustaining plant Pi supply on environmental Pi depletion.",
Arsenic,1355685,"Stress protein expression in primary and immortalized cultures of human thyroid cells: a model system for the study of stress proteins in the pathogenesis of autoimmune thyroid disease Abstract: Stress has, for many years, been linked to the onset of autoimmune disease and, in particular, autoimmune thyroid disease (AITD). Whilst the exact mechanism of this association is unknown, it is clear that episodes of stress can induce profound changes in the immune system. More specifically, recent studies from several laboratories have shown an association between the expression of stress proteins and, particularly, the Hsp70 family with AITD. Our own studies describe a thyroid-specific Hsp70 which shares antigenicity with the key thyroid autoantigen, thyroid peroxidase. Further studies on the molecular basis for this observation are, however, hampered by the lack of a suitably validated thyroid cell model. In this paper we compare the response of primary cultures of human thyrocytes to hyperthermia with the response seen in the immortalized human thyroid cell line HTori3. Both cell types responded in a broadly similar manner, synthesizing proteins from two of the major stress protein families, Hsp70 and Hsp90. In the primary human thyrocyte cultures the 70 kDa proteins showed a 7.5-fold increase and the 90 kDa proteins a 2.7-fold increase with hyperthermia whilst in the HTori3 cells the increases in response to hyperthermia were 10- and 6.5-fold, respectively. We also show a dose-dependent stress response in HTori3 cells cultured in the presence of arsenite ions. We conclude that the response of this highly differentiated and stable thyroid cell line to stress is similar to that seen in primary cultures of human thyroid cells and that these immortalized cells will afford a convenient and effective model for the further study of the role of stress in the pathology of AITD.",
Arsenic,1586452,Efficient removal of arsenate by versatile magnetic graphene oxide composites Abstract: ,
Arsenic,2343540,"Metal mobility and toxicity to microalgae associated with acidification of sediments: CO2 and acid comparison Abstract: The injection and storage of CO2 into marine geological formations has been suggested as a mitigation measure to prevent global warming. However, storage leaks are possible resulting in several effects in the ecosystem. Laboratory-scale experiments were performed to evaluate the effects of CO2 leakage on the fate of metals and on the growth of the microalgae Phaeodactylum tricornutum. Metal contaminated sediments were collected and submitted to acidification by means of CO2 injection or by adding HCl. Sediments elutriate were prepared to perform toxicity tests. The results showed that sediment acidification enhanced the release of metals to elutriates. Iron and zinc were the metals most influenced by this process and their concentration increased greatly with pH decreases. Diatom growth was inhibited by both processes: acidification and the presence of metals. Data obtained is this study is useful to calculate the potential risk of CCS activities to the marine environment.",
Arsenic,8278,"Arsenic levels in human blood, urine, and hair in response to exposure via drinking water Abstract: Five communities with water supplies having arsenic concentrations of 6, 51, 98, 123, and 393 ?g/liter were selected for study. Samples of blood, hair, urine, and tap water were obtained from participants in each community and analyzed for arsenic content. Results showed an increase in arsenic concentration for urine and hair samples as the water arsenic concentrations increased. Arsenic levels in blood did not show this trend until chronic toxicity was expected. We conclude that arsenic levels in water at concentrations of 100 ?g/liter or less seem not to produce an undue body burden.",
Arsenic,2149155,"Elevated blood pressure in offspring of rats exposed to diverse chemicals during pregnancy Abstract: Adverse intrauterine environments have been associated with increased risk of later cardiovascular disease and hypertension. In an animal model using diverse developmental toxicants, we measured blood pressure (BP), renal nephron endowment, renal glucocorticoid receptor (GR) gene expression, and serum aldosterone in offspring of pregnant Sprague-Dawley rats exposed to dexamethasone (Dex), perfluorooctane sulfonate (PFOS), atrazine, perfluorononanoic acid (PFNA), arsenic or nicotine. BP was assessed by tail cuff photoplethysmography, nephron endowment by confocal microscopy, and renal GR mRNA by qPCR. BP was also measured by telemetry, and corticosterone (CORT) was measured in resting or restrained Dex and atrazine offspring. Treated dams gained less weight during treatment in all groups except arsenic. There were chemical- and sex-specific effects on birth weight, but offspring body weights were similar by weaning. BP was higher in Dex, PFOS, atrazine and PFNA male offspring by 7-10 weeks. Female offspring exhibited elevated BP at 10 weeks for PFNA and arsenic, and at 37 weeks for Dex, PFOS and atrazine. Dex, PFOS and atrazine offspring still exhibited elevated BP at 52-65 weeks of age; others did not. Elevated BP was associated with lower nephron counts. Dex, PFOS and atrazine offspring had elevated renal GR gene expression. Elevations in BP were also observed in Dex and atrazine offspring by radiotelemetry. Atrazine offspring exhibited enhanced CORT response to restraint. Elevated offspring BP was induced by maternal exposure to toxicants. Since all treatments affected maternal gestational weight gain, maternal stress may be a common underlying factor in these observations.",
Arsenic,1326914,"Biphasic effect of arsenite on cell proliferation and apoptosis is associated with the activation of JNK and ERK1/2 in human embryo lung fibroblast cells Abstract: Biphasic dose-response relationship induced by environmental agents is often characterized with the effect of low-dose stimulation and high-dose inhibition. Some studies showed that arsenite may induce cell proliferation and apoptosis via biphasic dose-response relationship in human cells; however, mechanisms underlying this phenomenon are not well understood. In the present study, we aimed at investigating the relationship between biphasic effect of arsenite on cell proliferation and apoptosis and activation of JNK and ERK1/2 in human embryo lung fibroblast (HELF) cells. Our results demonstrated that cell proliferation may be stimulated at lower concentrations (0.1 and 0.5 microM) arsenite but inhibited at higher concentrations (5 and 10 microM). When cell apoptosis was used as the endpoint, the concentration-response curves were changed to U-shapes. During stimulation phospho-JNK levels were significantly increased at 3, 6, and 12 h after 0.1 or 0.5 microM arsenite exposure. Phospho-ERK1/2 levels were increased with different concentrations (0.1-10 microM) of arsenite at 6, 12, and 24 h. Blocking of JNK pathway with 20 microM SP600125 or ERK1/2 by 100 microM PD98059 significantly inhibited biphasic effect of arsenite in cells. Data in the present study suggest that activation of JNK and ERK1/2 may be involved in biphasic effect of arsenite when measuring cell proliferation and apoptosis in HELF cells. JNK activation seems to play a more critical role than ERK1/2 activation in the biphasic process.",
Arsenic,1579264,Transport and Retention of Heavy Metal in Soils: Competitive Sorption Abstract: ,
Arsenic,1025804,"Reverse osmosis filter use and high arsenic levels in private well water Abstract: Inorganic arsenic causes cancer, and millions of people worldwide are exposed to arsenic-contaminated water. Regulatory standards for arsenic levels in drinking water generally do not apply to private domestic wells. Reverse osmosis (RO) units commonly are used by well owners to reduce arsenic concentrations, but may not always be effective. In a survey of 102 homes in Nevada, 19 used RO devices. Pre- and post-RO filtration arsenic concentrations averaged 443 microg/l and 87 microg/l, respectively. The average absolute and percent reductions in arsenic concentrations after filtration were 356 microg/l and 79%, respectively. Postfiltration concentrations were higher than 10 microg/l in 10 homes and higher than 100 microg/l in 4 homes. These findings provide evidence that RO filters do not guarantee safe drinking water and, despite regulatory standards, some people continue to be exposed to very high arsenic concentrations.",
Arsenic,2064178,"Using Bayesian networks to discover relations between genes, environment, and disease Abstract: ",
Arsenic,2149175,"PML isoforms in response to arsenic: High resolution analysis of PML body structure and degradation Abstract: Arsenic is a clinically effective treatment for acute promyelocytic leukaemia (APL) in which the promyelocytic leukaemia (PML) protein is fused to retinoic receptor alpha (RAR?). PML-RAR? is degraded by the proteasome via a SUMO-dependent, ubiquitin-mediated pathway in response to arsenic treatment, curing the disease. Due to alternative splicing, six major PML isoforms are expressed, each of which encodes a unique C-terminal region. Using a system in which only a single EYFP-linked PML isoform is expressed, we demonstrate that PML I, II and VI accumulate in the cytoplasm following arsenic treatment, whereas PML III, IV and V do not. 3D structured illumination was employed to obtain super-resolution images of PML bodies, revealing spherical shells of PML along with associated SUMO. Arsenic treatment results in dramatic and isoform specific changes to PML body ultrastructure. After extended arsenic treatment most PML isoforms are degraded, leaving SUMO at the core of the nuclear bodies. A high content imaging assay identifies PML V as the isoform most readily degraded following arsenic treatment, and PML IV as relatively resistant to degradation. Immunoprecipitation analysis demonstrates that all PML isoforms are SUMO and ubiquitin modified after arsenic treatment and by using siRNA we demonstrate that arsenic induced degradation of all PML isoforms is dependent on the ubiquitin E3 ligase RNF4. Intriguingly, depletion of RNF4 results in marked accumulation of PML V, suggesting this isoform is an optimal substrate for RNF4. Thus the variable C-terminal domain influences the rate and location of degradation of PML isoforms following arsenic treatment.",
Arsenic,1345473,"Methylation, oxidation state and membrane permeability determine toxicity of arsenic compounds Abstract: As described by the Challenger Mechanism, mammalian metabolism of inorganic arsenic is a series of reductions and oxidative methylations meaning that tri- and pentavalent methylarsenic species are formed. We investigated cyto-/genotoxic effects of arsenate Asi(V), arsenite Asi(III), monomethylarsonic acid MMA(V), monomethylarsonous acid MMA(III), dimethylarsinic acid DMA(V), dimethylarsinous acid DMA(III) and trimethylarsine oxide TMAO(V) after an extended exposure time of 24 h and compared the uptake capabilities of fibroblasts (CHO-9) used for genotoxicity studies, with those of hepatic cells (HepG2). In addition, we forced cellular uptake of arsenic compounds into CHO cells by electroporation. Our results show that trivalent arsenicals exerted higher cytotoxic effects than pentavalent species in both cell lines. Furthermore, the methylated trivalent species MMA(III) and DMA(III) were significantly more cytotoxic than inorganic Asi(III) or (V). DMA(III) was the most membrane permeable species in both cell lines and induced strong genotoxic effects in CHO cells. In contrast, MMA(III) was more reactive in HepG2 cells. The uptake of all other arsenic species was relatively low (<1 % by HepG2 and <4 % by CHO cells), but was dose-dependent. Electroporation increased intracellular arsenic as well as the number of induced MN. With exception of Asi(III) and DMA(III) in CHO, the tested arsenicals were not bound to cell membranes, but were present in the cytosol. This may indicate the existence of DMA(III)-specific exporter proteins as are known for Asi(III). It may be hypothesized that the greater genotoxic effects observed in CHO are due to the higher uptake of arsenicals into this cell type. Our results indicate that uptake of arsenic compounds is highly dependent upon both cell type and arsenic species. The degree of methylation and the oxidation state determine the membrane permeability of arsenicals and finally its toxicity.",
Arsenic,1797831,"The evolution of December 2004 tsunami deposits: Temporal and spatial distribution of potentially toxic metalloids Abstract: The article presents the results of research into the content of metalloid fractions in the tsunami deposits from southern Thailand. The following fractions, which are potentially most easily released from deposits to the environment, have been distinguished: the water soluble fraction, the exchangeable fraction extracted with the phosphate buffer and the fraction eluted with the solution of hydrochloric acid. The analytical technique atomic absorption spectrometry with hydride generation was applied. Spatial variability of the metalloid fractions in deposits and changes occurring in deposits over a period of several years of observation were determined. Based on the statistical analysis of the results, an attempt was made to determine the post-depositional release of deposits components to the environment. Based on the conducted research, the 4years forming process of the arsenic, antimony and selenium occurrence after the deposition of sediments on land were described, as well as the balance in the amount of deposit components released to the environment.",
Arsenic,627753,"Effects of arsenite on UROtsa cells: Low-level arsenite causes accumulation of ubiquitinated proteins that is enhanced by reduction in cellular glutathione levels Abstract: Chronic arsenic exposure increases risk for the development of diabetes, vascular disease, and cancers of the skin, lung, kidney, and bladder. This study investigates the effects of arsenite [As(III)] on human urothelial cells (UROtsa). As(III) toxicity was determined by exposing confluent UROtsa cells to As(III) (0.5-200 microM). Depleting cellular glutathione levels with buthionine sulfoximine (BSO) potentiated the toxicity of As(III). Cell viability was assessed with the (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. UROtsa cell ability to biotransform As(III) was determined by dosing cells with environmentally relevant concentrations of As(III) followed by HPLC/ICP-MS analysis of cell media and lysate. Both pentavalent and trivalent monomethylated products were detected. Although cytotoxicity was observed at high doses of As(III) (approximately 100 microM) in UROtsa cells, perturbations of a variety of molecular processes occurred at much lower doses. Exposure to low-level As(III) (0.5-25 microM) causes an accumulation of ubiquitin (Ub)-conjugated proteins. This effect is enhanced when cellular glutathione levels have been reduced with BSO treatment. Because As(III) has many effects on UROtsa cells, a greater understanding of how As(III) is affecting cellular proteins in a target tissue will lead to a better understanding of the mechanism of toxicity and pathogenesis for low-level As(III).",
Arsenic,628541,"Arsenic groundwater contamination and sufferings of people in North 24-Parganas, one of the nine arsenic affected districts of West Bengal, India Abstract: To understand the magnitude of the arsenic calamity in West Bengal, a detailed study spanning 7 years was made in North 24-Parganas, one of the nine arsenic affected districts. Area and population of North 24-Parganas district are 4093.82 sq. km and 7.3 million, respectively. Fourty eight thousand and thirty water samples were analyzed from hand tubewells of North 24-Parganas in use for drinking, cooking and 29.2% of the tubewells were found to have arsenic above 50 microg/L, the maximum permissible limit of World Health Organization (WHO) and 52.8% have arsenic above 10 microg/L, WHO recommended value of arsenic in drinking water. Out of the 22 blocks of North 24-Parganas, in 20 blocks arsenic has been found above the maximum permissible limit and so far in 16 blocks people have been identified as suffering from arsenical skin lesions. From the generated data, it is estimated that about 2.0 million and 1.0 million people are drinking arsenic contaminated water above 10 microg/L and 50 microg/L level, respectively in North 24-Parganas alone. So far, in our preliminary study 33,000 people have been examined at random from arsenic affected villages in North 24-Parganas and 2274 people have been registered with arsenical skin lesions. Extrapolation of the available data indicates about 0.1 million people may be suffering from arsenical skin lesions from North 24-Parganas alone. A sum of 21,000 hair, nail, and urine samples analyses from arsenic affected villages show 56%, 80%, and 87% people have arsenic in biological specimen more than normal/toxic (hair) level, respectively. Thus, many may be subclinically affected. Due to use of arsenic contaminated groundwater for agricultural irrigation, rice and vegetable are getting arsenic contaminated. Hence there is an additional arsenic burden from food chain. People from arsenic affected villages are also suffering from arsenical neuropathy. A followup study indicates that many of the victims suffering from severe arsenical skin lesions for several years are now suffering from cancer or have already died of cancer.",
Arsenic,1597363,Engineering the soil bacterium Pseudomonas putida for arsenic methylation Abstract: Accumulation of arsenic has potential health risks through consumption in food. Here we inserted the gene As(III) S-adenosylmethionine methyltransferase (ArsM) into the chromosome of Pseudomonas putida KT2440. Recombinant bacteria methylate inorganic arsenic into less toxic organoarsenicals. This has potential for bioremediation of environmental arsenic and reducing arsenic contamination in food.,
Arsenic,1797836,"Effect of Text Messaging to Deter Early Resumption of Sexual Activity after Male Circumcision for HIV Prevention: A Randomized Controlled Trial Abstract: <strong>BACKGROUND:: </strong>Resumption of sex before complete wound healing after male circumcision may increase risk of post-operative surgical complications, and HIV acquisition and transmission. We aimed to determine the effect of text messaging to deter resumption of sex before 42 days post-circumcision.<br /><br /><strong>METHODS:: </strong>We conducted a randomized trial where men &gt;18 years old who owned mobile phones and had just undergone circumcision were randomized to receive a series of text messages (n=600) or usual care (n=600). The primary outcome was self-reported resumption of sex before 42 days.<br /><br /><strong>RESULTS:: </strong>Sex before 42 days was reported by 139/491 (28.3%) men in the intervention group and 124/493 (25.2%) in the control group (relative risk=1.13, 95% CI 0.91-1.38, p=0.3). Men were more likely to resume early if they were married or had a live-in sexual partner (adjusted relative risk [aRR] 1.57, 95% CI 1.18-2.08, p&lt;0.01); in the month before circumcision had one (aRR 1.50, 95% CI 1.07-2.12, p=0.02) or &gt;1 (aRR 1.81, 95% CI 1.24-2.66, p&lt;0.01) sexual partner(s); had primary school or lower education (aRR 1.62, 95% CI 1.33-1.97, p&lt; 0.001); were employed (aRR 1.35, 95% CI 1.05-1.72, p=0.02); or were 21-30 years old (aRR 1.58, 95% CI 1.01-2.47, p=0.05); 31-40 (aRR 1.91, 95% CI 1.18-3.09, p&lt;0.01) or &gt;40 years old (aRR 1.76, 95% CI 1.04-2.97, p=0.03) compared to &lt;21 years old.<br /><br /><strong>CONCLUSIONS:: </strong>Text messaging as used in this trial did not reduce early resumption of sex after circumcision. We identified key risk factors for early resumption that need to be considered in circumcision programs.",
Arsenic,1351581,Reducing total mercury and methylmercury accumulation in rice grains through water management and deliberate selection of rice cultivars Abstract: ,
Arsenic,1034368,"The suitability of the dry ashing procedure for determination of arsenic in marine samples Abstract: The dry ashing procedure with Mg/(NO3)2/Mgo ashing aid, followed by arsenic determination by colorimetry, has been compared to an X-ray fluorescence method for determination of arsenic in marine samples. Good agreement between these techniques indicated the suitability of the dry ashing, colorimetric procedure for determination of &quot;fish-arsenic&quot;. A wet digestion procedure using HNO3-H2SO4-HC104 was also shown to be suitable.",
Arsenic,627399,"Transplacental arsenic plus postnatal 12-O-teradecanoyl phorbol-13-acetate exposures associated with hepatocarcinogenesis induce similar aberrant gene expression patterns in male and female mouse liver Abstract: Our prior work shows that in utero arsenic exposure alone is a complete transplacental carcinogen, producing hepatocellular carcinoma in adult male offspring but not in females. In a follow-up study to potentially promote arsenic-initiated tumors, mice were exposed to arsenic (85 ppm) from gestation day 8 to 18 and then exposed to 12-O-teradecanoyl phorbol-13-acetate (TPA), a well-known tumor promoter after weaning. The dermal application of TPA (2 mug/0.1 ml acetone, twice/week for 21 weeks) after transplacental arsenic did not further increase arsenic-induced liver tumor formation in adult males but significantly increased liver tumor formation in adult females. Thus, for comparison, liver tumors and normal liver samples taken from adult male and female mice at necropsy were analyzed for aberrant gene/protein expression by microarray, real-time RT-PCR and Western blot analysis. Arsenic/TPA treatment resulted in increased expression of alpha-fetoprotein, k-ras, c-myc, estrogen receptor-alpha, cyclin D1, cdk2na, plasminogen activator inhibitor-1, cytokeratin-8, cytokeratin-18, glutathione S-transferases and insulin-like growth factor binding proteins in liver and liver tumors from both male and female mice. Arsenic/TPA also decreased the expression of BRCA1, betaine-homocysteine methyltransferase, CYP7B1, CYP2F2 and insulin-like growth factor-1 in normal and cancerous livers. Alterations in these gene products were associated with arsenic/TPA-induced liver tumors, regardless of sex. Thus, transplacental arsenic plus postnatal TPA exposure induced similar aberrant gene expression patterns in male and female mouse liver, which are persistent and potentially important to the mechanism of arsenic initiation of hepatocarcinogenesis.",
Arsenic,1346227,"Subcellular partitioning of elements and availability for trophic transfer: Comparison between the bivalve Cerastoderma edule and the polychaete Diopatra neapolitana Abstract: Metal transference through food-chain can constitute a serious problem, particularly in coastal systems, where macrobenthic organisms are often exposed to metal contamination. Previous studies have shown that the elements accumulated in macrobenthic organisms can either be precipitated or soluble in the cells. Whilst differences in the subcellular distribution between fractions are described for Cd, Cu and Zn, little is known for other elements such as As, Pb or Hg, despite their toxicity. The present study compared the subcellular partitioning of several elements in two different macrobenthic species, the bivalve Cerastoderma edule and the polychaete Diopatra neapolitana, and the potential that each element has to be trophically available was determined. There were differences in element accumulation between the two species: D. neapolitana presented a higher concentration of Zn and As while, C. edule accumulated more Al, Ni and Pb. The results obtained for the soluble fraction showed that the elements in higher concentration were, for both species, Al and Zn. In addition to these two elements, Cu, Cd, Cr and As concentrations in this fraction were higher in D. neapolitana than in C. edule, although the bivalve presented higher Ni levels. These results give a good estimate of the amount of elements more readily available to be trophically transferred. The relative amount of metal present in the soluble fraction may indicate more clearly the ability of each species to cope with each element and thus their propensity to allocate subcellular elements, regardless of the environment that it inhabits. The percentage of elements in the soluble fraction showed that C. edule had a high predisposition to compartmentalise As and Cd in the trophically available fraction, given that the other elements were preferentially in the insoluble fraction. In contrast, D. neapolitana distributes metals and As more evenly throughout both fractions. As our study simultaneously evaluated the different elements, this gave a more precise idea of the real contamination that passes to higher trophic levels, especially in the elements that have high toxicity and which had not yet been evaluated (Hg, Pb, and As). This shows that contamination of the food webs of an ecosystem is not only dependent on its chemical contamination, but also on the organisms at each trophic level.",
Arsenic,1508616,"Homicide by poisoning Abstract: ABSTRACT: By studying the number and method of homicidal poisoning in Miami-Dade County, Florida; New York City, NY; Oakland County, Michigan; and Sweden, we have confirmed that this is an infrequently established crime.Several difficulties come with the detection of homicidal poisonings. Presenting symptoms and signs are often misdiagnosed as natural disease, especially if the crime is committed in a hospital environment, suggesting that an unknown number of homicides go undetected.In the reported cases analyzed, the lethal agent of choice has changed over the years. In earlier years, traditional poisons such as arsenic, cyanide, and parathion were frequently used. Such poisonings are nowadays rare, and instead, narcotics are more commonly detected in victims of this crime.",
Arsenic,2345625,"Metals in tissues of migrant semipalmated sandpipers (Calidris pusilla) from Delaware Bay, New Jersey Abstract: There is an abundance of field data on levels of metals for feathers in a variety of birds, but relatively few data for tissues, especially for migrant species from one location. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in muscle, liver, brain, fat and breast feathers from migrant semipalmated sandpipers (Calidris pusilla) collected from Delaware Bay, New Jersey. Our primary objectives were to (1) examine variation as a function of tissue, (2) determine the relationship of metal levels among tissues, and (3) determine the selenium:mercury molar ratio in different tissues since selenium is thought to protect against mercury toxicity. We were also interested in whether the large physiological changes that occur while shorebirds are on Delaware Bay (e.g. large weight gains in 2-3 weeks) affected metal levels, especially in the brain. There were significant differences among tissues for all metals. The brain had the lowest levels of arsenic and cadmium, and was tied for the lowest levels of all other metals except lead and selenium. Correlations among metals in tissues were varied, with mercury levels being positively correlated for muscle and brain, and for liver and breast feathers. Weights vary among individuals at the Delaware Bay stopover, as they arrive light, and gain weight prior to migration north. Bird weight and levels of arsenic, cadmium, and selenium in the brain were negatively correlated, while they were positively correlated for lead. There was no positive correlation for mercury in the brain as a function of body weight. The selenium:mercury molar ratio varied significantly among tissues, with brain (ratio of 141) and fat having the highest ratios, and liver and breast feathers having the lowest. In all cases, the ratio was above 21, suggesting the potential for amelioration of mercury toxicity.",
Arsenic,1015711,"Heterologous expression of the yeast arsenite efflux system ACR3 improves Arabidopsisthaliana tolerance to arsenic stress Abstract: • Arsenic contamination has a negative impact on crop cultivation and on human health. As yet, no proteins have been identified in plants that mediate the extrusion of arsenic. Here, we heterologously expressed the yeast (Saccharomyces cerevisiae) arsenite efflux transporter ACR3 into Arabidopsis to evaluate how this affects plant tolerance and tissue arsenic contents. • ACR3 was cloned from yeast and transformed into wild-type and nip7;1 Arabidopsis. Arsenic tolerance was determined at the cellular level using vitality stains in protoplasts, in intact seedlings grown on agar plates and in mature plants grown hydroponically. Arsenic efflux was measured from protoplasts and from intact plants, and arsenic levels were measured in roots and shoots of plants exposed to arsenate. • At the cellular level, all transgenic lines showed increased tolerance to arsenite and arsenate and a greater capacity for arsenate efflux. With intact plants, three of four stably transformed lines showed improved growth, whereas only transgenic lines in the wild-type background showed increased efflux of arsenite into the external medium. The presence of ACR3 hardly affected tissue arsenic levels, but increased arsenic translocation to the shoot. • Heterologous expression of yeast ACR3 endows plants with greater arsenic resistance, but does not lower significantly arsenic tissue levels.",
Arsenic,1019770,"Arsenite stimulates poly(ADP-ribosylation) by generation of nitric oxide Abstract: Recent studies indicate that arsenic may generate reactive oxygen species to exert its toxicity. Because reactive oxygen species are known to induce poly(ADP-ribosylation), which is implicated in DNA repair, signal transduction, and apoptosis, we have investigated the effect of arsenite on poly(ADP-ribosylation). The results showed that arsenite treatment induced poly(ADP-ribosylation), NAD depletion, DNA strand breaks, and micronuclei in CHO-K1 cells. Increase of nitrite level, a stable product of nitric oxide, was also detected in medium of arsenite-treated cultures. S-methyl-L-thiocitrulline and N omega-nitro-L-arginine methyl ester, inhibitors of nitric oxide synthase, could suppress the arsenite-induced NAD depletion, DNA strand breaks, and micronuclei, whereas 3-aminobenzamide, an inhibitor of poly (ADP-ribose) polymerase, could enhance micronucleus production and NAD depletion in arsenite-treated cells. These results suggest that arsenite treatment may generate nitric oxide to damage DNA and which then stimulate poly(ADP-ribosylation). Because arsenite also induced DNA strand breaks and NAD depletion in bovine aortic endothelial cells, and these could also be suppressed by S-methyl-L-thiocitrulline, the induction of nitric oxide may be important to the etiology of arsenic-induced vascular disorders in humans.",
Arsenic,1377974,"Inhibition of embryonic catalase by arsenicals as a potential mechanism of dysmorphogenesis Abstract: The adverse developmental effects of arsenicals are well established. Exogenous antioxidants (e.g. glutathione peroxidase) ameliorate the dysmorphogenic effects of arsenite and to a lesser degree arsenate in whole embryo culture. To determine the origin of reactive oxygen species (ROS) we measured embryonic catalase activity at varying times after exposure to arsenicals in CD-1 mouse conceptuses in culture. M arsenite (that induces 100% malformations) produced a progressive decrease in embryonic catalase activity. After 6H of exposure there is a trend towards a reduction in activity (13% reduction) and a 33% reduction after 12H of exposure. By 24H catalase activity was reduced 75% by 5 uM arsenite. Catalase activity was reduced 45% by 4 uM and 21% by 3 uM arsenite after 24H. 20 uM arsenate produced a 25% reduction and 10 uM arsenate produced no effect on catalase activity after 24H. Therefore, one mechanism for ROS accumulation produced by arsenicals appears to be an inhibition in endogenous antioxidant defenses. In order to determine if inhibition of catalase would produce malformations, 3-6 somite stage conceptuses were exposed to 3-amino-1,2,4-triazole (3-AT), an irreversible catalase inhibitor. 3-AT produced dysmorphogenesis in embryos after a 26H culture period. The heart and pharyngeal arches were most sensitive to 3-AT and neural tube closure defects are not a major effect of 3-AT exposure. Therefore, inhibition of catalase does not reproduce the full spectrum of arsenical-induced dysmorphogenesis, but does induce the facial and heart effects. These studies suggest that the dysmorphogenic effects of arsenicals are not produced by a single biochemical effect.",
Arsenic,1380127,RESPONSE OF CHESAPEAKE BAY USA PHYTOPLANKTON COMMUNITIES TO LOW LEVELS OF TOXIC SUBSTANCES Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM DIATOMS CYANOPHYTE ARSENIC SILVER HIGHER TROPHIC LEVEL EFFECTS,
Arsenic,1797837,"Randomised, double-blind, placebo-controlled trial to determine whether steroids reduce the incidence and severity of nephropathy in Henoch-Schönlein Purpura (HSP) Abstract: BACKGROUND: The long-term prognosis of Henoch-Schönlein Purpura (HSP) is predominantly determined by the extent of renal involvement. There is no consensus as to whether treatment with prednisolone at presentation can prevent or ameliorate the progression of nephropathy in HSP.<br /><br /><strong>METHODS: </strong>Children under 18 years of age with new-onset HSP were randomly assigned to receive prednisolone or placebo for 14 days. The primary outcomes were (a) the presence of proteinuria at 12 months (defined as urine protein?:?creatinine ratio (UP?:?UC) &gt;20 mg/mmol) and (b) the need for additional treatment (defined as the presence of hypertension requiring treatment or renal biopsy anomalies or the need for treatment of renal disease) during the 12 month study period.<br /><br /><strong>RESULTS: </strong>352 children were randomised. Of those patients with laboratory UP?:?UC results available at 12 months, 18/123 (15%) patients on prednisolone and 13/124 (10%) patients on placebo had UP?:?UC &gt;20 mg/mmol. There was no significant difference in the proportion of patients with UP?:?UC &gt;20 mg/mmol at 12 months between the treatment groups (OR (prednisolone/placebo)=1.46, 95% CI 0.68 to 3.14, n=247), even after adjusting for baseline proteinuria and medications known to affect proteinuria (adjusted OR=1.29, 95% CI 0.58 to 2.82, n=247). Similarly, there was no significant difference in the time needed for additional treatment between the two groups (hazard ratio (HR) (prednisolone/placebo)=0.53, 95% CI 0.18 to 1.59, n=323).<br /><br /><strong>CONCLUSIONS: </strong>This is the largest trial of the role of steroids in children with HSP. We found no evidence to suggest that early treatment with prednisolone reduces the prevalence of proteinuria 12 months after disease onset in children with HSP.<br /><br /><strong>TRIAL REGISTRATION NUMBER: </strong>ISRCTN71445600.",
Arsenic,627292,"Effects of 12 metal ions on iron regulatory protein 1 (IRP-1) and hypoxia-inducible factor-1 alpha (HIF-1?) and HIF-regulated genes Abstract: Several metal ions that are carcinogenic affect cellular iron homeostasis by competing with iron transporters or iron-regulated enzymes. Some metal ions can mimic a hypoxia response in cells under normal oxygen tension, and induce expression of HIF-1alpha-regulated genes. This study investigated whether 12 metal ions altered iron homeostasis in human lung carcinoma A549 cells as measured by an activation of IRP-1 and ferritin level. We also studied hypoxia signaling by measuring HIF-1alpha protein levels, hypoxia response element (HRE)-driven luciferase reporter activity, and Cap43 protein level (an HIF-1alpha responsive gene). Our results show the following: (i) Ni(II), Co(II), V(V), Mn(II), and to a lesser extent As(III) and Cu(II) activated the binding of IRP-1 to IRE after 24 h, while the other metal ions had no effect; (ii) 10 of 12 metal ions induced HIF-1alpha protein but to strikingly different degrees. Two of these metal ions, Al(III) and Cd(II), did not induce HIF-1alpha protein; however, as indicated below, only Ni(II), Co (II), and to lesser extent Mn(II) and V(V) activated HIF-1alpha-dependent transcription. The combined effects of both [Ni(II) + As(III)] and [Ni(II) + Cr(VI)] on HIF-1alpha protein were synergistic; (iii) Addition of Fe(II) with Ni(II), Co(II), and Cr(VI) attenuated the induction of HIF-1alpha after 4 h treatment; (iv) Ni(II), Co(II), and Mn(II) significantly decrease ferritin level after 24 h exposure; (v) Ni(II), Co(II), V(V), and Mn(II) activated HRE reporter gene after 20 h treatment; (vi) Ni(II), Co(II), V(V), and Mn(II) increased the HIF-1-dependent Cap43 protein level after 24 h treatment. In conclusion, only Ni (II), Co (II), and to a lesser extent Mn(II) and V(V) significantly stabilized HIF-1alpha protein, activated IRP, decreased the levels of ferritin, induced the transcription of HIF-dependent reporter, and increased the expression of Cap43 protein levels (HIF-dependent gene). The mechanism for the significant stabilization and elevation of HIF-1alpha protein which drives these other parameters was previously shown by us and others to involve a loss of cellular Fe as well as inhibition of HIF-1alpha-dependent prolyl hydroxylases which target the binding of VHL ubiquitin ligase and degrade HIF-1alpha. Even though there were small effects of some of the other metals on IRP and HIF-1alpha, downstream effects of HIF-1alpha activation and therefore robust hypoxia signaling were only observed with Ni(II), Co(II), and to much lesser extents with Mn(II) and V(V) in human A549 lung cells. It is of interest that the metal ions that were most effective in activating hypoxia signaling were the ones that were poor inducers of metallothionein protein and also decreased Ferritin levels, since both of these proteins can bind metal ions and protect the cell against toxicity in human lung cells. It is important to study effects of these metals in human lung cells since this represents a major route of human environmental and occupational exposure to these metal ions.",
Arsenic,8265,"Implications of the multistage theory of carcinogenesis applied to occupational arsenic exposure Abstract: The multistage theory of carcinogenesis and its implications for evaluating the effect of exposure to carcinogens in the workplace are described. This theory predicts different relationships between excess carcinogenic risk and duration of exposure, age at initial exposure, and follow-up time since exposure stopped. These relationships are shown to depend on the stage of the carcinogenic process affected by the carcinogen, i.e., action at an early stage or a later stage. The patterns of excess lung cancer mortality were examined for a cohort of copper smelter workers exposed to atmospheric arsenic and other contaminants. Under this multistage hypothesis, the results indicate that arsenic appears to exert a definite effect on a late stage of the carcinogenic process, although an additional effect at the initial stage cannot be conclusively ruled out. Other factors, such as exposure to sulfur dioxide in the environment, calendar year at start of employment, and the potential bias resulting from incomplete exposure histories are also discussed as well as the implications of these results to experimental animal studies.",
Arsenic,628430,"Analysis of p16 gene mutation, deletion and methylation in patients with arseniasis produced by indoor unventilated-stove coal usage in Guizhou, China Abstract: The aim of this study was to determine p16 gene mutation, deletion, and promoter 5' CpG island hypermethylation in peripheral blood mononuclear leukocyte of patients with arseniasis as attributed to exposure to indoor unventilated coal stove. The role of the aberrant change of p16 gene in the induction and development of carcinogenesis in endemic arsenisiasis region in China was also examined. Polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP), multiplex PCR (mPCR), methylation-specific PCR (MSP), and sequencing techniques were performed to detect (1) mutation of the p16 gene exon 2, (2) homozygous deletion of the p16 gene exon 1 and exon 2, and (3) hypermethylation of the promoter CpG island in peripheral blood mononuclear leukocyte of patients with arseniasis. Results showed no mutation was found in exon 2 of p16 gene. The homozygous deletion frequency of p16 gene was 5 and 15% in control and arseniasis patients, respectively. The homozygous deletion occurred mainly in exon 2, with significant deletion frequencies of 9, 13, and 20% in mild, intermediate, and severe arseniasis groups. The significant homozygous deletion frequency was 9 and 39% in noncarcinoma and carcinoma individuals. The positive rate of p16 gene promoter CpG island hyermethylation was 42 and 2% in the exposed group and the control group, respectively. The positive rate was 26, 42, and 50% in mild, intermediate, and severe arseniasis. The marked different positive rate was 22 and 56% in noncarcinoma and carcinoma individuals, respectively. In conclusion, homozygous deletion and hypermethylation of p16 gene may play an important role in the initiation and development of manifestations seen in endemic arseniasis including carcinogenesis.",
Arsenic,1936211,"Development of polaron-transformed explicitly correlated full configuration interaction method for investigation of quantum-confined Stark effect in GaAs quantum dots Abstract: The effect of external electric field on electron-hole (eh) correlation in gallium arsenide quantum dots is investigated. The electron-hole Schrodinger equation in the presence of an external electric field is solved using explicitly correlated full configuration interaction method and accurate exciton binding energy and electron-hole recombination probability are obtained. The effect of the electric field was included in the 1-particle single component basis functions by performing variational polaron transformation. The quality of the wavefunction at small inter-particle distances was improved by using Gaussian-type geminal function that depended explicitly on the electron-hole separation distance. The parameters of the explicitly correlated function were determined variationally at each field strength. The scaling of total exciton energy, exciton binding energy, and electron-hole recombination probability with respect to the strength of the electric field was investigated. It was found that a 500 kV/cm change in field strength reduces the binding energy and recombination probability by a factor of 2.6 and 166, respectively. The results show that the eh-recombination probability is affected much more strongly by the electric field than the exciton binding energy. Analysis using the polaron-transformed basis indicates that the exciton binding should asymptotically vanish in the limit of large field strength.",
Arsenic,1020684,"Arsenic exposure and human papillomavirus response in non-melanoma skin cancer Mexican patients: A pilot study Abstract: We assessed the relationships between chronic arsenic (As) exposure, human papilloma virus (HPV) contact and non-melanoma skin cancer (NMSC) by means of a dermatology clinic-based case-control study (42 cases and 48 controls) in Region Lagunera, Mexico, where chronic As poisoning is endemic. Exposure was determined through detailed history of residence in the As-contaminated area and measurement of As levels in drinking water and urine. We used a consensus epitope from the central region of L1 protein of the HPV family to determine antibodies against HPV. A history of As exposure and HPV seropositivity were associated with increased NMSC risks. A history of exposure to high levels of As increased the risk for NMSC (OR = 4.53; P = 0.11) in the group of seronegative HPV patients. A positive response to HPV significantly increased the OR for NMSC to 9.04 (P = 0.01) when history showed exposure to low levels of As. Interestingly, the OR was significantly increased to 16.5 (P = 0.001) when both exposure to high levels of As and HPV seropositivity were present. In addition, the presence of NMSC increased the OR (5.45; P = 0.03) for a positive response to HPV when history showed exposure to low levels of As, but the OR was increased to 8.0 (P = 0.005) in the cases with high exposure levels. Thus, HPV infection could constitute an additional risk factor for NMSC development in humans chronically exposed to As. However, further studies with additional populations are needed to determine the interaction between HPV and As exposure in NMSC.",
Arsenic,628548,"Early detection of illness associated with poisonings of public health significance Abstract: Since September 11, 2001, concern about potential terrorist attacks has increased in the United States. To reduce morbidity and mortality from outbreaks of illness from the intentional release of chemical agents, we examine data from the Toxic Exposure Surveillance System (TESS). TESS, a national system for timely collection of reports from US poison control centers, can facilitate early recognition of outbreaks of illness from chemical exposures. TESS data can serve as proxy markers for a diagnosis and may provide early alerts to potential outbreaks of covert events. We use 3 categories of information from TESS to detect potential outbreaks, including call volume, clinical effect, and substance-specific data. Analysis of the data identifies aberrations by comparing the observed number of events with a threshold based on historical data. Using TESS, we have identified several events of potential public health significance, including an arsenic poisoning at a local church gathering in Maine, the TOPOFF 2 national preparedness exercise, and contaminated food and water during the northeastern US blackout. Integration of poison control centers into the public health network will enhance the detection and response to emerging chemical threats. Traditionally, emergency physicians and other health care providers have used poison control centers for management information; their reporting to these centers is crucial in poisoning surveillance efforts.",
Arsenic,1034480,"Diseases diagnosed in broiler chicken flocks in Victoria, Australia, 1977 to 1984 Abstract: During the period July 1977 to June 1984, specimens from 1402 broiler chicken flocks were submitted to the Veterinary Research Institute, Victoria, Australia for investigation of morbidity, mortality and, or, poor performance. A total of 19,450 post mortem examinations, as well as numerous ancillary tests, were performed. The findings on these flocks are presented and the consequences of some particular diseases noted.",
Arsenic,1789318,"On the antiquity of metalloenzymes and their substrates in bioenergetics Abstract: Many metalloenzymes that inject and extract reducing equivalents at the beginning and the end of electron transport chains involved in chemiosmosis are suggested, through phylogenetic analysis, to have been present in the Last Universal Common Ancestor (LUCA). Their active centres are affine with the structures of minerals presumed to contribute to precipitate membranes produced on the mixing of hydrothermal solutions with the Hadean Ocean ~4billion years ago. These mineral precipitates consist of transition element sulphides and oxides such as nickelian mackinawite ([Fe&gt;Ni]2S2), a nickel-bearing greigite (~FeSS[Fe3NiS4]SSFe), violarite (~NiSS[Fe2Ni2S4]SSNi), a molybdenum bearing complex (~Mo(IV/VI)2Fe3S(0/2-)9) and green rust or fougerite (~[Fe(II)Fe(III)(OH)4](+)[OH](-)). They may be respectively compared with the active centres of Ni-Fe hydrogenase, carbon monoxide dehydrogenase (CODH), acetyl coenzyme-A synthase (ACS), the complex iron-sulphur molybdoenzyme (CISM) superfamily and methane monooxygenase (MMO). With the look of good catalysts - a suggestion that gathers some support from prebiotic hydrothermal experimentation - and sequestered by short peptides, they could be thought of as the original building blocks of proto-enzyme active centres. This convergence of the makeup of the LUCA-metalloenzymes with mineral structure and composition of hydrothermal precipitates adds credence to the alkaline hydrothermal (chemiosmotic) theory for the emergence of life, specifically to the possibility that the first metabolic pathway - the acetyl CoA pathway - was initially driven from either end, reductively from CO2 to CO and oxidatively and reductively from CH4 through to a methane thiol group, the two entities assembled with the help of a further thiol on a violarite cluster sequestered by peptides. By contrast, the organic coenzymes were entirely a product of the first metabolic pathways. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.",
Arsenic,2347618,"Levels of heavy metals and trace elements in umbilical cord blood and the risk of adverse pregnancy outcomes: A population-based study Abstract: To better understand the relationship between prenatal exposure to heavy metals and trace elements and the risk of adverse pregnancy outcomes, we investigated the status of heavy metals and trace elements level in a Chinese population by collecting umbilical cord blood. Umbilical cord blood heavy metals and trace elements concentrations were determined by inductively coupled plasma-mass spectrometry. No differences with statistical significance in the median arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), strontium (Sr), thallium (Tl), vanadium (V), and zinc (Zn) concentrations were observed between the adverse pregnancy outcome group and the reference group. Titanium (Ti) and antimony (Sb) were found at higher levels with statistical significance in the cord blood samples with adverse pregnancy group when compared to the ones in the reference group. The association between Ti levels and the risk of adverse pregnancy outcomes remained significant after adjusting for potential confounding factors, including newborn weight. These results indicated that environmental exposure to Ti may increase the risk of adverse pregnancy outcomes in Chinese women without occupational exposure.",
Arsenic,48666,"Herbal medicine as a cause of combined lead and arsenic poisoning Abstract: 1. Combined chronic lead and arsenic poisoning was diagnosed in a 33-year-old Korean woman following consumption of a Korean herbal medicine prescribed for haemorrhoids. 2. The patient had malaise, severe difficulty walking, arthralgia, oedema and abdominal pain with diarrhoea. 3. Investigation showed anaemia with basophilic stippling, fragmentation and a raised reticulocyte count. 4. Raised blood and urine lead levels and urine arsenic levels were found. 5. Analysis of the herbal medicine revealed a high lead and arsenic content. 6. Treatment with the newer chelating agent 2,3-dimercaptosuccinic acid was successful, with no detectable side-effects.",
Arsenic,1019632,"Involvement of reactive oxygen species and caspase 3 activation in arsenite-induced apoptosis Abstract: Recent studies indicate that arsenic may generate reactive oxygen species to exert its toxicity. However, the mechanism is still unclear. In this study, we demonstrate that arsenite is able to induce apoptosis in a concentration- and time-dependent manner; however, arsenate is unable to do so. An increase of intracellular peroxide levels was accompanied with arsenite-induced apoptosis, as demonstrated by flow cytometry using DCFH-DA. N-Acetyl-L-cysteine (a thiol-containing antioxidant), diphenylene iodonium (an inhibitor of NADPH oxidase), 4,5-dihydro-1,3-benzene disulfonic acid (a selective scavenger of O2-), and catalase significantly inhibit arsenite-induced apoptosis and intracellular fluorescence intensity. In contrast, allopurinol (an inhibitor of xanthine oxidase), indomethacin (an inhibitor of cyclooxygenase), superoxide dismutase, or PDTC had no effect on arsenite-induced cell death. Activation of CPP32 activity, PARP (a DNA repair enzyme) degradation, and release of cytochrome c from mitochondria to the cytosol are involved in arsenite-induced apoptosis, and Bcl-2 antagonize arsenite-induced apoptosis by a mechanism that interferes in the activity of CPP32. These results lead to a working hypothesis that arsenite-induced apoptosis is triggered by the generation of hydrogen peroxide through activation of flavoprotein-dependent superoxide-producing enzymes (such as NADPH oxidase), and hydrogen peroxide might play a role as a mediator to induce apoptosis through release of cytochrome c to cytosol, activation of CPP32 protease, and PARP degradation.",
Arsenic,626470,"Assessment of genotoxicity of 14 chemical agents used in dental practice: Ability to induce chromosome aberrations in Syrian hamster embryo cells Abstract: To assess the genotoxicity of 14 chemical agents used as locally applied agents in dental practice, the ability of these agents to elicit chromosome aberrations was examined using Syrian hamster embryo (SHE) cells. Chromosome aberrations in SHE cells were induced by treatment with three of eight chemical agents used as endodontic medicaments, i.e. ethylenediaminetetraacetic acid (EDTA), formocresol (a mixture of formalin and tricresol), and sodium arsenite. The other five chemical agents, i.e. chloramphenicol, p-chlorophenol, p-phenolsulfonic acid, sodium hypochlorite, and tetracycline hydrochloride exhibited a negative response for chromosome aberrations. Assessment of three dyes used for disclosing dental plaque showed chromosome aberrations induced by basic fuchsin but not by acid fuchsin and erythrosine B. Three local anesthetics, lidocaine hydrochloride, prilocaine hydrochloride, and procaine hydrochloride, were negative for chromosome aberrations. Among the ten chemical agents that exhibited a negative response in the assay, p-chlorophenol, sodium hypochlorite, and erythrosine B induced chromosome aberrations in SHE cells when treated in the presence of exogenous metabolic activation. The percentages of cells with polyploidy or endoreduplication were enhanced by formocresol, sodium arsenite, p-chlorophenol, p-phenolsulfonic acid, sodium hypochlorite, erythrosine B, prilocaine hydrochloride, and procaine hydrochloride in the absence or presence of exogenous metabolic activation. Our results indicate that the chemical agents that had a positive response in the present study are potentially genotoxic to mammalian cells.",
Arsenic,2149289,"Assessment of metals concentration and ecotoxicology of the sediment core of Rehri Creek, Karachi Coast, Pakistan Abstract: Trace metal concentrations were investigated in a recent sediment core collected from the Rehri Creek area of the Karachi coast, Sindh - Pakistan. The core was sliced horizontally at 2.5-cm intervals to determine grain size, sediment composition, pH, organic matter, and acid-leach able trace metals: cadmium, chromium, copper, lead, and zinc. The trace metals were analyzed by ICP. To separate anthropogenic from geogenic input, several approaches were made, including comparison with sediment quality guidelines—ecotoxicological sense of heavy metal contamination and classification by quantitative indexes. Grain-size analysis and sediment composition of core sample show a sandy nature with neutral pH. Elemental sequence (ES) of the trace metals is in the order of Zn (19.2–109.56 ppm) > Si (66.46–101.71 ppm) > Ba (12.05–26.86 ppm) > As (8.18–17.36 ppm) > Ni (4.2–14.69 ppm) > Cr (3.02–9.62 ppm) > Pb (2.79–6.83 ppm) > Cu (2.2–5.29 ppm) > Co (0.9–2.05 ppm). Thus it is likely that the area may face a serious threat of metal pollution with the present deposition rates unless stringent pollution control norms are adopted. The Sediment Geo-accumulation Index shows that there is no Cr, Cu, Ni, Pb, Zn, or Fe pollution; however, the former index and the Pollution Load Index indicate arsenic pollution in the sediments.",
Arsenic,2279440,"Heavy metals induce oxidative stress and genome-wide modulation in transcriptome of rice root Abstract: Industrial growth, ecological disturbances and agricultural practices have contaminated the soil and water with many harmful compounds, including heavy metals. These heavy metals affect growth and development of plants as well as cause severe human health hazards through food chain contamination. In past, studies have been made to identify biochemical and molecular networks associated with heavy metal toxicity and uptake in plants. Studies suggested that most of the physiological and molecular processes affected by different heavy metals are similar to those affected by other abiotic stresses. To identify common and unique responses by different metals, we have studied biochemical and genome-wide modulation in transcriptome of rice (IR-64 cultivar) root after exposure to cadmium (Cd), arsenate [As(V)], lead (Pb) and chromium [Cr(VI)] in hydroponic condition. We observed that root tissue shows variable responses for antioxidant enzyme system for different heavy metals. Genome-wide expression analysis suggests variable number of genes differentially expressed in root in response to As(V), Cd, Pb and Cr(VI) stresses. In addition to unique genes, each heavy metal modulated expression of a large number of common genes. Study also identified cis-acting regions of the promoters which can be determinants for the modulated expression of the genes in response to different heavy metals. Our study advances understanding related to various processes and networks which might be responsible for heavy metal stresses, accumulation and detoxification.",
Arsenic,1344480,"Inhibition of arsenite-induced apoptosis by aspirin Abstract: Arsenite exposure and subsequent arsenite-induced toxicity and carcinogenesis are common in many countries. Thus the study of chemopreventive compounds that inhibit arsenite-induced toxicity and carcinogenesis is very valuable. In the present work, we investigated the effect of aspirin on arsenite-induced apoptosis and signal transduction by means of luciferase activity, apoptosis analysis and Western blotting. Arsenite induced AP-1 transcriptional activity at the same concentration (20 microM) as was effective for inducing apoptosis. Arsenite-induced apoptosis and AP-1 transactivation in JB6 cells were blocked by aspirin and salicylate (SA). Both aspirin and SA inhibited arsenite-induced phosphorylation of Erks, but had no effect on phosphorylation of JNKs. SA inhibited arsenite-induced phosphorylation of p38 kinase, but aspirin did not. These results indicate that aspirin and SA inhibit arsenite-induced apoptosis through the inhibition of the Erks/AP-1 pathway.",
Arsenic,1797747,"Arsenite retards the cardiac differentiation of rat cardiac myoblast H9c2 cells Abstract: It is well known that exposure to inorganic arsenic through groundwater leads not only to cancer and cardiovascular disease, but also to detrimental effects on development. In this study, we investigated the effects of arsenite on the cardiac differentiation of rat myoblast H9c2 cells. The cardiac differentiation of H9c2 cells cultured in media containing 1% fetal bovine serum and all-trans retinoic acid was confirmed by enhanced expression of cardiac troponin T (cTnT), the appearance of multinucleated cells, and cell cycle arrest at G0/G1 phase. Exposure of H9c2 cells to inorganic arsenite (As(III)) during cardiac differentiation suppressed the appearance of the morphological and biological characteristics observed in the cardiac phenotype of H9c2 cells. In addition, As(III) inhibited PKC? phosphorylation, which is detected in early-stage differentiation. These results suggest that As(III) retards the cardiac differentiation of H9c2 cells, at least partly, via the inhibition of PKC? phosphorylation.",
Arsenic,1015745,"Arsenate toxicity and stress responses in the freshwater ciliate Tetrahymena pyriformis Abstract: The arsenic metabolism in different biological organisms has been studied extensively. However, little is known about protozoa. Herein, we investigated the cell stress responses of the freshwater ciliate Tetrahymena pyriformis to arsenate toxicity. An acute toxicity assay revealed an 18-h EC(50) arsenate concentration of ca. 40?M, which caused significant changes in the cell shape, growth and organism mobility. Whereas, under exposure to 30?M arsenate, T. pyriformis could grow reasonably well, indicating a certain resistance of this organism. Arsenic speciation analysis revealed that 94-98% of the total arsenate in cells of T. pyriformis could be transformed to monomethylarsonic acid, dimethylarsinic acid and a small proportion of arsenite after 18h of arsenate exposure, thus indicating the major detoxification pathway by arsenic oxidation/reduction and biomethylation. Finally, comparative proteomic analysis unveiled significant changes in the expression of multiple proteins involved in anti-oxidation, sugar and energy metabolism, proteolysis, and signal transduction. Our results revealed multiple pathways of arsenate detoxification in T. pyriformis, and indicated that protozoa may play important roles in the biogeochemical cycles of arsenic.",
Arsenic,1172924,"The distribution and fate of arsenic in the Waikato River system, North Island, New Zealand Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenic levels were determined in waters, sediments, aquatic macrophytes and other organisms taken from the Waikato River system, North Island, New Zealand. All water samples contained elevated levels of arsenic relative to 0.0017 mug g-1, the background level for arsenic in aquatic systems. Most water samples taken between Lakes Aratiatia and Whakamaru had arsenic levels above the World Health Organization (WHO) limit for arsenic in drinking water (0.01 mug mL-1). Arsenic levels in the water of the river decreased downstream from the Wairakei and Ohaaki geothermal power stations, indicating that these are major sources of arsenic to the river. The arsenic concentration of the sediments was typically around 30 mug g-1, though there was a large variation. Sediments appear to be a sink for arsenic. Some aquatic macrophytes (Ceratophylium demersum and Egeria densa) had arsenic concentrations up to 1,000 mug g-1, (0.1%) in dried tissue. These plants may be used as bioindic",
Arsenic,1028138,"Induction of metallothionein I by arsenic via metal-activated transcription factor 1: critical role of C-terminal cysteine residues in arsenic sensing Abstract: Metal-activated transcription factor 1 (MTF1) mediates the induction of metallothioneins I and II by zinc and stress signals. The mechanism of MTF1 activation has not been well understood. We analyzed the interaction between arsenic (As(3+)) and MTF1 for Mt1 induction. As(3+) potently induces Mt1 mRNA expression in mouse hepa1c1c7 cells. Induction is dependent upon functional MTF1 as induction is lost in Mtf1 knockout cells but is restored upon reconstitution with Mtf1; moreover, As(3+) induces the binding of MTF1 to the metal response elements of endogenous Mt1. Induction is not affected by modulating zinc concentrations but is markedly enhanced by cycloheximide. Phenylarsine oxide (PAO), which covalently binds to vicinal protein cysteine thiol groups, induces Mt1 with a magnitude of higher potency than that of As(3+). PAO affinity beads effectively pulls down the carboxyl half of MTF1 (MTF1(321-675)) by binding to a cluster of five cysteine residues near the terminus. Preincubation with As(3+), Cd(2+), Co(2+), Ni(2+), Ag(+), Hg(2+), and Bi(3+) blocks pulldown of MTF1(321-675) by PAO beads in vitro and in vivo, indicating that binding of the metal inducers to the same C-terminal cysteine cluster as PAO occurs. Deletion of the C-terminal cysteine cluster or mutation of the cysteine residues abolishes or markedly reduces the transcription activation activity of MTF1 and the ability of MTF1 to restore Mt1 induction in Mtf1 knockout cells. The findings demonstrate a critical role of the C-terminal cysteine cluster of MTF1 in arsenic sensing and gene transcription via arsenic-cysteine thiol interaction.",
Arsenic,2064238,"Risk of laryngeal and nasopharyngeal cancer associated with arsenic and cadmium in the Tunisian population Abstract: Chronic exposure to heavy metals has long been recognized as being capable of increasing head and neck cancer (HNC) incidence, such as laryngeal (LC) and nasopharyngeal (NPC), among exposed human populations. The aim of the present study was to evaluate the concentrations of arsenic (As) and cadmium (Cd) in the blood of 145 patients (LC and NPC) and 351 controls in order to establish a potential relationship between these factors and the occurrence of LC and NPC. Mean blood levels of As and Cd in patients (5.67 and 3.51 ?g/L, respectively) were significantly higher than those of controls (1.57 and 0.74 ?g/L, respectively). The blood levels of As and Cd were mostly significantly higher than those of controls (p?<?0.05) after controlling the other risk factors of HNC including tobacco smoking and chewing, and alcohol drinking. Cd levels in blood increase significantly with the number of occupational exposure years for patients (p?<?0.05). However, seafood was not found to be contributing as an exposure source. Among these risk factors, smoking (>30 pack years) and occupational exposure (>20 years) presented the most significant association with HNC (OR?=?10.22 and 10.38, respectively, p?<?0.001). Cd level in blood sample of cases that are occupationally exposed/tobacco users (smokers and chewers) were higher than that of non-occupationally exposed/nontobacco users (p?<?0.001). The logistic regression model illustrated that HNC (LC?+?NPC) was significantly associated with blood levels of As (OR?=?2.41, p?<?0.001) and Cd (OR?=?4.95, p?<?0.001).",
Arsenic,1345260,"Heat shock induces I kappa B-alpha and prevents stress-induced endothelial cell apoptosis Abstract: <strong>OBJECTIVE: </strong>To determine whether prior heat shock would attenuate endothelial cell apoptosis and whether any effect of preemptive heat shock is mediated through a nuclear factor kappa B and inhibitor kappa B alpha mechanism.<br /><br /><strong>DESIGN: </strong>A randomized, controlled in vitro study.<br /><br /><strong>SETTING: </strong>A laboratory in a large, academic medical center.<br /><br /><strong>INTERVENTIONS: </strong>Cultured primary porcine endothelial cells were treated with increasing doses of sodium arsenite (40-160 micromol/L), after which the interval until subsequent apoptotic (lipopolysaccharide-arsenite) challenge was varied (4-16 hours). The degree of cell death and apoptosis were determined using neutral red uptake and staining with annexin V and propidium iodide, respectively. Inducible heat shock protein 70 and inhibitor kappa B alpha levels in treated cells were determined by Western blot analysis. Lipopolysaccharide-induced nuclear factor kappa B activity was assessed using an electrophoretic mobility shift assay.<br /><br /><strong>RESULTS: </strong>Prior arsenite treatment decreased cell death by apoptosis in a time- and dose-dependent manner. Specifically, a higher sodium arsenite concentration and shorter intervals afforded better protection (P=.01, 160 micromol/L at 4 hours). Protection against apoptosis correlated with increased heat shock protein 70 and inhibitor kappa B alpha levels and decreased nuclear factor kappa B binding activity.<br /><br /><strong>CONCLUSIONS: </strong>Arsenite, an inducer of the heat shock response, decreased stress-induced endothelial cell apoptosis. The mechanism of this protection may include decreased nuclear factor kappa B activity or increased inducible heat shock protein 70 levels. Heat shock protein 70 may serve as a molecular marker to determine not only the phenotypic state of the cell but also the durability of protection afforded by heat shock. These data support the hypothesis that stress-induced changes in transcription factor activity and protein expression can regulate the induction of apoptosis.",1
Arsenic,711046,"Systemic manifestations in chronic arsenic toxicity in absence of skin lesions in West Bengal Abstract: Pigmentation and keratosis are the prerequisites to diagnose arsenicosis. However, many systemic manifestations occur in association with pigmentation and keratosis in people exposed to chronic drinking of arsenic contaminated water. The present study aim to find out whether systemic manifestations occur in significant number of cases in arsenic exposed people in the absence of skin lesions in an affected district in West Bengal, India.<br /><br /> A cross-sectional study was carried out in South 24 Parganas, an arsenic affected district of West Bengal, India. Both dermatological and systemic manifestations were recorded and water samples collected for arsenic analysis from 7683 participants. A correlation of systemic manifestations in relation to arsenic exposure was carried out in subjects having no arsenical skin lesion. Prevalence odds ratio (POR) was calculated for each outcome comparing those with high arsenic exposure with those with lowest exposure.<br /><br /> The frequency of occurrence of various clinical manifestations like weakness, anaemia, diarrhoea, hepatomegaly and lung disease was found to be significantly higher among participants drinking water having arsenic concentration > or = 50 microg/l in comparison to those taking water with arsenic content below this level. Further, there was increased occurrence of these manifestations with increasing concentration of arsenic level in drinking water, and this followed a dose-response relationship.<br /><br /> It appears that it is worthwhile to include people with systemic manifestations in absence of skin lesions with evidence of arsenic exposure as suspected cases of arsenicosis for case detection and in surveillance programme.",
Arsenic,2278240,SpringerBriefs in Immunology Leishmania and Leishmaniasis Preface Abstract: ,
Arsenic,1025517,"A petition to Mr Peel: Gideon Mantell and the trial of Hannah Russell Abstract: In the summer of 1826, Hannah Russell was tried for petty treason, viz. the murder of her husband, Benjamin Russell, by poisoning. Their lodger, Daniel Leney, was indicted as her accomplice. The exact circumstances surrounding the death were unclear but Hannah was known to have purchased white arsenic (arsenious oxide). A local surgeon, Thomas Evans, supported at the post-mortem examination by two further surgeons, not only reported severe corrosion of the gastrointestinal tract, but also the recovery of nearly an eighth of an ounce of arsenic from the victim's stomach. Both accused were convicted and sentenced to death. Leney was executed, but Hannah Russell was respited because the trial judge, Sir Robert Graham, had doubts as to a direction he had given to the jury. The surgeon and paleontologist Gideon Mantell took up her case, stressing that death from arsenic could not have taken place as quickly as was alleged and maintaining that the chemical evidence of arsenic poisoning was inconclusive. He gained the support of some eminent chemists and physicians. Subsequently, forensic toxicologists [Sir] Robert Christison and Alfred Swaine Taylor pointed out that Mantell's arguments as to the possible time to death in arsenic poisoning were quite wrong. Moreover, Evans gave details of the analyses he and his colleagues had undertaken to Christison, who pronounced the findings sound, as indeed did Mantell after Evans and his colleagues published details of their investigations in the Sussex Advertiser. Papers in The National Archives show that Hannah was pardoned for the offence for which she was indicted, leaving it open to prefer a lesser charge. That this was never done may have been due to Mantell's campaign, at least in part, but the pardon she did receive was due to the concern of the trial judge as to the implications of the evidence presented at trial.",
Arsenic,1237548,"A transgenic mouse model for the detection of cellular stress induced by toxic inorganic compounds Abstract: BIOSIS COPYRIGHT: BIOL ABS. Transgenic mice for genotoxicity testing have been developed, although no such models have been produced for the evaluation of toxic, nongenotoxic chemical compounds. We have developed a transgenic mouse model for the analysis of toxic inorganic compounds. We engineered a mouse lineage with the human growth hormone (hGH) gene under the control of the human hsp70 promoter, in which a plasma-detectable hGH response can be elicited by exposure to heat shock. In primary cell cultures from these mice, hGH release was observed following treatment with several toxic inorganics. Transgenic mice injected intraperitoneally with sodium arsenite, cadmium chloride, copper sulphate, or methylmercurium chloride showed significant hGH levels in plasma.",
Arsenic,710976,"Long isoforms of NRF1 contribute to arsenic-induced antioxidant response in human keratinocytes Abstract: Human exposure to inorganic arsenic (iAs), a potent oxidative stressor, causes various dermal disorders, including hyperkeratosis and skin cancer. Nuclear factor-erythroid 2-related factor 1 (NRF1, also called NFE2L1) plays a critical role in regulating the expression of many antioxidant response element (ARE)-dependent genes.<br /><br /> We investigated the role of NRF1 in arsenic-induced antioxidant response and cytotoxicity in human keratinocytes.<br /><br /> In cultured human keratinocyte HaCaT cells, inorganic arsenite (iAs3+) enhanced the protein accumulation of long isoforms (120-140 kDa) of NRF1 in a dose- and time-dependent fashion. These isoforms accumulated mainly in the nuclei of HaCaT cells. Selective deficiency of NRF1 by lentiviral short-hairpin RNAs in HaCaT cells [NRF1-knockdown (KD)] led to decreased expression of ?-glutamate cysteine ligase catalytic subunit (GCLC) and regulatory subunit (GCLM) and a reduced level of intracellular glutathione. In response to acute iAs3+ exposure, induction of some ARE-dependent genes, including NAD(P)H:quinone oxidoreductase 1 (NQO1), GCLC, and GCLM, was significantly attenuated in NRF1-KD cells. However, the iAs3-induced expression of heme oxygenase 1 (HMOX-1) was unaltered by silencing NRF1, suggesting that HMOX-1 is not regulated by NRF1. In addition, the lack of NRF1 in HaCaT cells did not disturb iAs3+-induced NRF2 accumulation but noticeably decreased Kelch-like ECH-associated protein 1 (KEAP1) levels under basal and iAs3+-exposed conditions, suggesting a potential interaction between NRF1 and KEAP1. Consistent with the critical role of NRF1 in the transcriptional regulation of some ARE-bearing genes, knockdown of NRF1 significantly increased iAs3+-induced cytotoxicity and apoptosis.<br /><br /> Here, we demonstrate for the first time that long isoforms of NRF1 contribute to arsenic-induced antioxidant response in human keratinocytes and protect the cells from acute arsenic cytotoxicity.",
Arsenic,1381756,"Comparison of NAOH fusion and microwave oven digestion for the determination of arsenic and selenium in coal fly ash reference material using hydride generation-atomic absorption spectrometry Abstract: A method is described for the determination of As and Se in coal fly ash standard reference material SRM NIST-1633b, using microwave oven digestion with a Parr bomb and hydride generation. The results obtainedwith this preocedure agree well with the certified values. The methodis further compared with the NaOH fusion dissolution procedure. The limit of detection for As and Se was 0.25 ng/mL and 0.8 ng/mL, respectively. The characteristic concentration, corresponding to 0.0044 absorbance signal, was 0.35 ng/mL for As and 0.88 ng/mL for Se.",
Arsenic,1797786,"Tetravalent manganese feroxyhyte: a novel nano-adsorbent equally selective for As(III) and As(V) removal from drinking water Abstract: The development of a single-phase Fe/Mn oxy-hydroxide (?-Fe0.76Mn0.24OOH), highly efficient at adsorbing both As(III) and As(V), is reported. Its synthesis involves the co-precipitation of FeSO4 and KMnO4 in a kilogram-scale continuous process, in acidic and strongly oxidizing environments. The produced material was identified as a manganese feroxyhyte in which tetravalent manganese is homogeneously distributed into the crystal unit, whereas a second-order hollow spherical morphology is favored. According to this structuration, the oxy-hydroxide maintains the high adsorption capacity for As(V) of a single Fe oxy-hydroxide combined with enhanced As(III) removal based on the oxidizing mediation of Mn(IV). Ion-exchange between arsenic species and sulfates as well as the strongly positive surface charge further facilitate arsenic adsorption. Batch adsorption tests performed in natural-like water, indicate that Mn(IV)-feroxyhyte can remove 11.7 ?g As(V)/mg and 6.7 ?g As(III)/mg at equilibrium pH 7, before residual concentration overcomes the regulation limit of 10 ?g As/L for drinking water. The improved efficiency of this material, its low cost and the possibility for scaling-up its production to industry indicate the high practical impact and environmental importance of this novel adsorbent.",
Arsenic,557718,"Biomarkers of oxidative stress and damage in human populations exposed to arsenic Abstract: Arsenic (As) is an ubiquitous element in the environment for which the main route of human exposure is through consumption of drinking water. Reactive oxygen species generation (ROS) associated with As exposure is known to play a fundamental role in the induction of adverse health effects and disease (cancer, diabetes, hypertension, and cardiovascular and neurological diseases). However, the precise mechanisms of oxidative stress and damage from As exposure are not fully understood and moreover the use of non-invasive methods of measuring ROS generation and oxidative damage footprints in humans is no easy task. Although As induces adverse health effects not all exposed individuals develop degenerative chronic diseases or even manifest adverse effects or symptoms, suggesting that genetic susceptibility is an important factor involved in the human response to As exposure. This mini-review summarizes the literature describing the molecular mechanisms affected by As, as well as the most used biomarkers of oxidative stress and damage in human populations. The most reported biomarkers of oxidative DNA damage are the urinary excretion of 8-OHdG and the comet assay in lymphocytes, and more recently DNA repair mechanism markers from the base and nuclear excision repair pathways (BER and NER). Genetic heterogeneity in the oxidative stress pathways involved in As metabolism are important causative factors of disease. Thus further refinement of human exposure assessment is needed to reinforce study design to evaluate exposure-response relationships and study gene-environment interactions. The use of microarray-based gene expression analysis can provide better insights of the underlying mechanisms involved in As-induced diseases and could help to identify target genes that can be modulated to prevent disease.",
Arsenic,95503,"Nitric oxide and superoxide anion production in monocytes from children exposed to arsenic and lead in region Lagunera, Mexico Abstract: We evaluated in Mexican children environmentally exposed to arsenic and lead monocyte nitric oxide (NO) and superoxide anion production in response to direct activation with interferon-""gamma"" (IFN-""gamma"") + lipopolysaccharide (LPS). The integrity of Th1-regulated cellular immune response when monocytes were indirectly activated was also evaluated. Most children lived near a primary lead smelter. Lead and arsenic contamination in soil and dust by far exceeded background levels. As levels in water were between 10 and 30 ppb. Most children (93%) had urinary arsenic (AsU) concentrations above 50 Ág/l (range 16.75-465.75) and 65% had lead blood levels (PbB) above 10 Ág/dl (range 3.47-49.19). Multivariate analyses showed that NO production in monocytes activated indirectly was negatively associated with both PbB and AsU. Superoxide production in directly activated monocytes was negatively associated with AsU but positively associated with PbB. The models including the interaction term for AsU and PbB suggested the possibility of a negative interaction for NO production and a positive interaction for superoxide. There were indications of differential gender-based associations, NO production in indirectly activated monocytes obtained from girls was negatively associated with AsU but not with PbB. Superoxide production was positively associated with PbB in both directly and indirectly activated monocytes from boys but the latter was negatively associated with AsU. These effects are consistent with immune system abnormalities observed in human populations exposed to Pb or As. Further studies in larger populations are required to characterize As and Pb interactions and the mechanism(s) underlying the observed effects.",
Arsenic,2279391,"Long-term outcome following Thulium VapoEnucleation of the prostate Abstract: <strong>INTRODUCTION: </strong>To evaluate Thulium VapoEnucleation of the prostate (ThuVEP) for patients with symptomatic benign prostatic obstruction (BPO) with long-term follow-up.<br /><br /><strong>METHODS: </strong>A prospective analysis of 124 patients who underwent ThuVEP between January 2007 and July 2008 at our institution was done. ThuVEP was carried out using the 70-Watt 2-?m continuous wave Tm:YAG laser. Patient demographic, perioperative complications, and follow-up data were analysed.<br /><br /><strong>RESULTS: </strong>The median (interquartile range) preoperative prostate volume was 58.5 (45-70.75) cc. The median operation and enucleation time were 74 (60-100) and 32.54 (25.62-37.52) min, respectively. The median catheter time and postoperative hospital stay were 2 (2-2) and 4 (3-5) days, respectively. Nine (7.3 %) patients required a second-look operation in the immediate postoperative course (failed morcellation = 2, clot retention = 3, and residual adenoma = 4). Two patients needed blood transfusions (1.6 %) postoperatively. At 12-month follow-up, International Prostate Symptom Score (IPSS), quality of life (QoL), maximum urinary flow rate (Qmax), and postvoiding residual urine (PVR) improved significantly in comparison with preoperative assessment (p &lt; 0.001). A significant decrease of median PSA (4.7 vs. 0.92 ?g/l) was seen at one-year follow-up (p &lt; 0.001). At the 48-month follow-up mark, Qmax, PVR, IPSS, and QoL still differed significantly from baseline (p &lt; 0.001). Bladder neck contractures and urethral strictures each developed in 1.6 and 0.8 % of the patients during follow-up. None of the patients were re-treated during follow-up for recurrent prostatic tissue.<br /><br /><strong>CONCLUSIONS: </strong>ThuVEP is a safe, efficacious, and durable procedure for the treatment of BPO. The incidence of late complications with ThuVEP was low.",
Arsenic,1797825,"Long-term outcome of laparoscopic ileocecal resection for Crohn's disease before the era of biologics Abstract: <strong>BACKGROUND: </strong>Crohn's disease (CD) of the terminal ileum not responding to standard medical treatment is more and more treated with biologics instead of surgery. In order to get more information on the results of surgery, we analyzed the outcome of laparoscopic ileocecal resection (LICR) performed before the widespread use of these drugs.<br /><br /><strong>METHODS: </strong>Chart reviews and telephone follow-ups were performed on 119 patients treated with laparoscopic ileocecal resection for CD. Follow-ups were performed at a median of 58 (17-124) and 113(69-164)?months. Symptomatic restenosis requiring surgery or endoscopic dilatation was the primary endpoint. We further analyzed risk factors of recurrence.<br /><br /><strong>RESULTS: </strong>Of the 119 patients initially treated, 18 required surgery (n?=?14) or endoscopic dilatation (n?=?4). The calculated rates of re-intervention were 10 und 17.5 % at 5 and 10 years, respectively. Ninety percent of the patients had a Crohn-specific medication treatment at the time of surgery, but only 51.4 und 46.9 % at FU 1 und 2, respectively. Smoking increased the risk of recurrence (OR 3.7, P?=?0.011).<br /><br /><strong>CONCLUSION: </strong>The data demonstrate excellent long-term results of LICR for CD of the terminal ileum. Surgery should be considered as a first choice treatment in many patients with ileocecal CD not responding to conventional treatment.",
Arsenic,1579276,"Oil and flour of Cannabis sativa L. multiscreening analysis of mycotoxins, phthalates, polycyclic aromatic hydrocarbons, metals and pesticide residues Abstract: This paper describes the application of multiscreening methods aimed to the determination of mycotoxins, phthalates, polycyclic aromatic hydrocarbons, metals and phytoresidues in oil and flour obtained from Cannabis sativa L. This plant is cultivated for textile fiber production and extraction of oil from seeds and is used in food and folk medicinal preparations for its positive health benefits, including lowering of cholesterol and blood pressure. Moreover, due to the high content of polyunsaturated compounds, hemp seed oil has been used for printer's ink, wood preservative and also for detergents and soaps. <br> <br>The multiscreening analysis regarding mycotoxins (aflatoxin B1, B2, G1, G2, deoxynivalenol, ochratoxin A, zearalenone) and polycyclic aromatic hydrocarbons on oil and flour were negative for all components. The analysis of the main phthalates, used in plastic production, showed a fairly high content of diethylhexylphthalate in hemp oil, probably due to the type of packaging in which the sample was stored. <br> <br>The analysis of heavy metals (lead, cadmium, nickel, arsenic and chromium) and some metals from industrial processes (iron, copper and phosphorus) in the oil found no presence for the former and only few amounts of iron, copper and phosphorus. <br> <br>The hemp flour is instead found to be a potential source of micronutrients, such as iron, manganese and zinc, useful in human and animal nutrition, in addition to a high amount of phosphorus highly available, while the concentrations of the toxic metal compounds were below the limit of detection of the analytical methods. <br> <br>Execution of multiscreening analysis for pesticides revealed positive results for certain residues on oil, flour, and oil extracted from the flour, even if at low concentrations.",
Arsenic,1936036,"Novel pseudo SCCmec element ({Psi}SCCmec57395) in methicillin-resistant Staphylococcus pseudintermedius CC179 Abstract: Genetic characterization of methicillin-resistant Staphylococcus pseudintermedius (MRSP) from Thailand and Israel revealed the presence of a predominant atypical clonal lineage which was not typeable by SmaI-PFGE and SCCmec typing. All the isolates (n=34) belonged to CC179 (30 ST45, 2 ST179, 1 ST57, and 1 ST85 isolates). The isolates originated from healthy and diseased dogs and cats, as well as from the environment of one clinic. Cfr9I-PFGE and dru typing permitted the further distinction of CC179 isolates from the two different countries. Microarray analysis identified genes that confer resistance to ?-lactams (mecA; blaZ), aminoglycosides [aac(6')-Ie-aph(2')-Ia; aph(3')-III; ant (6)-Ia], macrolides and lincosamides [erm(B)], tetracyclines [tet(M)], trimethoprim [dfr(G)], streptothricin [sat4], and chloramphenicol [catpC221]. Fluoroquinolone resistance was attributed to specific amino acid substitutions, i.e. Ser84Leu in GyrA and Ser80Ile and Asp84Asn in GrlA. A novel pseudo staphylococcal cassette chromosome (?SCCmec57395) element was identified in MRSP strain 57395 (sequence type ST45) by whole genome sequencing. The 12,282-bp ?SCCmec57395 element contained a class C1 mec gene complex but no ccr genes. In addition to the methicillin resistance gene mecA, ?SCCmec57395 also carried determinants of resistance to heavy metals, such as arsenic, cadmium, and copper. Bsu36I restriction analysis of the ?SCCmec57395 element amplified by long range PCR revealed the presence of ?SCCmec57395 in the 33 additional isolates of MRSP CC179. The ?SCCmec57395 element represents a new class of SCCmec and has been identified in MRSP of CC179, which is a predominant clonal lineage in Israel and Thailand.",
Arsenic,1345144,"Evaluation of arsenic availability in sulfidic materials from gold mining areas in Brazil Abstract: This study is aimed at evaluating the availability and mobility of arsenic in sulfidic materials from gold mining areas in Minas Gerais State, Brazil. Eight extraction media were employed in a sequential extraction scheme, as follows: exchangeable As; strongly adsorbed As; As coprecipitated with acid-volatile sulfide, carbonates, MnO2, and Al2O3; As coprecipitated with amorphous iron; As linked to crystalline iron oxide; As coprecipitated with silicates; As coprecipitated with amorphous FeS2 and As2S3, and residual As, which was determined by GFAAS. Results demonstrated that in spite of differences in arsenic concentrations, the availability of the metalloid was found to be low for all samples. In general, arsenic was found in less available forms. Nevertheless, most of the arsenic in the environment is retained in the fractions 3, 4, and 5 which are susceptible to dissolution in acid medium, which in turn might be due to oxidation of the sulfide present in the samples.",
Arsenic,2149281,"Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching Abstract: ",
Arsenic,894634,"V-PROLI/NO, a nitric oxide donor prodrug, protects liver cells from arsenic-induced toxicity Abstract: Inorganic arsenic shows great promise in human cancer chemotherapy, although hepatotoxicity is a major limiting side-effect. O(2)-Vinyl 1-[2-(Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO) [Correction added after publication 19 December 2008: 1-[2-(Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO) was corrected to O(2)-Vinyl 1-[2-(Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO)] is a nitric oxide (NO) donor prodrug that is metabolized by liver cytochromes P450 to release NO. Other NO-releasing agents have been shown to mitigate arsenic toxicity. Thus, the effects of V-PROLI/NO pretreatment on the toxicity of inorganic arsenic (as NaAsO(2)) were studied in vitro in a human liver (HepG2) cell line. HepG2 cells acted upon the prodrug to release NO, as assessed by nitrite levels, in a dose- and time-dependent fashion to maximal levels of 57-fold above control levels. In cells pretreated with V-PROLI/NO (200 microM, 24 h) then exposed to arsenic for an additional 24 h, arsenic was much less toxic (LC(50) = 151.9 +/- 5.9 microM) than in control cells (LC(50) = 90.5 +/- 6.5 microM) and the reduced cytolethality was directly related to the level of NO produced. V-PROLI/NO also increased CYP2E1 transcriptional expression in a dose-dependent manner and CYP2E1 expression was directly related to the level of NO produced and the reduction in arsenic cytotoxicity. V-PROLI/NO pretreatment markedly reduced arsenic-induced apoptosis as measured by DNA fragmentation. Pretreatment with V-PROLI/NO suppressed phosphorylation of JNK1/2 after arsenic exposure. Arsenic increased metallothionein, a metal-binding protein important in arsenic tolerance, and V-PROLI/NO pretreatment caused additional increases in metallothionein levels. Thus, the prodrug, V-PROLI/NO, protects against arsenic toxicity in cultured human liver cells, reducing cytolethality, apoptosis and dysregulation of mitogen-activated protein kinases, through generation of NO formed after metabolism by liver cell enzymes, possibly including CYP2E1.",
Arsenic,1019207,"Touch-free in situ investigation of ancient Egyptian pigments Abstract: Some of the pigments painted on the Funerary Stele of Amenemhat (ca. 2000 B.C.) exhibited at the Egyptian Museum, Cairo and on the walls of the Tomb of Userhat (ca. 1420 B.C.), a rock-cut tomb in Thebes, Egypt, were investigated in situ using both a convenient home-made hand-held type of X-ray diffractometer and a commercial X-ray fluorescence spectrometer in a complementary way under touch-free conditions. CaCO3.3MgCO3 (huntite) was found in the white-painted parts of these two ancient monuments. An arsenic (As)-bearing phase was detected in the yellow-painted parts of the latter monument. The occurrence of huntite in Egypt has not been reported previously.",
Arsenic,627449,"Arsenic exposure from drinking water and birth weight Abstract: BACKGROUND: Arsenic exposures from drinking water increase the risk of various cancers and noncancer health endpoints. Limited evidence suggests that arsenic may have adverse human reproductive effects. We investigated the association between drinking water arsenic exposure and fetal growth, as manifest in birth weight. METHODS: We conducted a prospective cohort study in two Chilean cities with contrasting drinking water arsenic levels: Antofagasta (40 micro g/L) and Valparaíso (<1 micro g/L). Study subjects completed in-depth interviews and provided urine samples for exposure analysis. We obtained pregnancy and birth information from medical records. The birth weight analysis was restricted to liveborn, singleton infants born between December 1998 and February 2000. RESULTS: The final study group consisted of 424 infants from Antofagasta and 420 from Valparaíso. After controlling for confounders, results of the multivariable analysis indicated that Antofagasta infants had lower mean birth weight (-57 g; 95% confidence interval = -123 to 9). CONCLUSION: This study suggests that moderate arsenic exposures from drinking water (<50 micro g/L) during pregnancy are associated with reduction in birth weight, similar in magnitude to that resulting from other environmental exposures such as environmental tobacco smoke and benzene.",
Arsenic,628363,"Emodin enhances arsenic trioxide-induced apoptosis via generation of reactive oxygen species and inhibition of survival signaling Abstract: Although arsenic trioxide (As(2)O(3)) induces apoptosis in a relatively wide spectrum of tumors, the sensitivity of different cell types to this treatment varies to a great extent. Because reactive oxygen species (ROS) are critically involved in As(2)O(3)-induced apoptosis, we attempted to explore the possibility that elevating the cellular ROS level might be an approach to facilitate As(2)O(3)-induced apoptosis. Emodin, a natural anthraquinone derivative, was selected because its semiquinone structure is likely to increase the generation of intracellular ROS. Its independent and synergistic effects with As(2)O(3) in cytotoxicity were studied, and the plausible signaling mechanism was investigated in HeLa cells. Cell Proliferation Assay and flow cytometry were used to assess cell viability and apoptosis. Electrophoretic mobility shift assay, luciferase reporter assay, and Western blotting were performed to analyze signaling alteration. The results demonstrated that coadministration of emodin, at low doses of 0.5-10 micro M, with As(2)O(3) enhanced As(2)O(3)-rendered cytotoxicity on tumor cells, whereas these treatments caused no detectable proproliferative or proapoptotic effects on nontumor cells. ROS generation was increased, and activation of nuclear factor kappaB and activator protein 1 was suppressed by coadministration. All enhancements by emodin could be abolished by the antioxidant N-acetyl-L-cysteine. Therefore, we concluded that emodin sensitized HeLa cells to As(2)O(3) via generation of ROS and ROS-mediated inhibition on two major prosurvival transcription factors, nuclear factor kappaB and activator protein 1. This result allows us to propose a novel strategy in chemotherapy that uses mild ROS generators to facilitate apoptosis-inducing drugs whose efficacy depends on ROS.",
Arsenic,2278422,"Signal-peptide-mediated translocation is regulated by a p97-AIRAPL complex Abstract: Protein homoeostasis is a fundamental requirement for all living cells in order to survive in a dynamic surrounding. Proper levels of AIRAPL (arsenite-inducible RNA-associated protein-like protein) (ZFAND2B) are required in order to maintain cellular folding capacity in metazoans, and functional impairment of AIRAPL results in acceleration of aging and protein aggregation. However, the cellular roles of AIRAPL in this process are not known. In the present paper, we report that AIRAPL binds and forms a complex with p97 [VCP (valosin-containing protein)/Cdc48], Ubxd8 (ubiquitin regulatory X domain 8), Npl4-Ufd1, Derlin-1 and Bag6 on the ER (endoplasmic reticulum) membrane. In spite of the fact that AIRAPL complex partners are involved in the ERAD (ER-associated degradation) process, AIRAPL knockdown does not show any impairment in ERAD substrate degradation. However, translocation into the ER of a subset of ERAD- and non-ERAD-secreted proteins are regulated by AIRAPL. The ability to regulate translocation by the p97-AIRAPL complex is entirely dependent on the proteins' signal peptide. Our results demonstrate a p97 complex regulating translocation into the ER in a signal-peptide-dependent manner.",
Arsenic,1777681,"Topical efficacy of dimercapto-chelating agents against lewisite-induced skin lesions in SKH-1 hairless mice Abstract: Lewisite is a potent chemical warfare arsenical vesicant that can cause severe skin lesions. Today, lewisite exposure remains possible during demilitarization of old ammunitions and as a result of deliberate use. Although its cutaneous toxicity is not fully elucidated, a specific antidote exists, the British anti-lewisite (BAL, dimercaprol) but it is not without untoward effects. Analogs of BAL, less toxic, have been developed such as meso-2,3-dimercaptosuccinic acid (DMSA) and have been employed for the treatment of heavy metal poisoning. However, efficacy of DMSA against lewisite-induced skin lesions remains to be determined in comparison with BAL. We have thus evaluated in this study the therapeutic efficacies of BAL and DMSA in two administration modes against skin lesions induced by lewisite vapor on SKH-1 hairless mice. Our data demonstrate a strong protective efficacy of topical application of dimercapto-chelating agents in contrast to a subcutaneous administration 1h after lewisite exposure, with attenuation of wound size, necrosis and impairment of skin barrier function. The histological evaluation also confirms the efficacy of topical application by showing that treatments were effective in reversing lewisite-induced neutrophil infiltration. This protective effect was associated with an epidermal hyperplasia. However, for all the parameters studied, BAL was more effective than DMSA in reducing lewisite-induced skin injury. Together, these findings support the use of a topical form of dimercaprol-chelating agent against lewisite-induced skin lesion within the first hour after exposure to increase the therapeutic management and that BAL, despite its side-effects, should not be abandoned.",
Arsenic,1614969,"Arsenic Methylation in Soils and Its Relationship with Microbial arsM Abundance and Diversity, and As Speciation in Rice Abstract: Methylation of arsenic in soil influences its environmental behavior and accumulation by plants, but little is known about the factors affecting As methylation. As speciation was determined in the pore waters of 6 soils from diverse geographical locations over 54 days of incubation under flooded conditions. The concentration of methylated As (monomethylarsonic acid, MMA, and dimethylarsinic acid, DMA) varied from 0 to 85 µg L-1 (0 - 69% of the total As in pore water). Two Bangladeshi paddy soils contaminated by irrigation of As-laden groundwater produced large concentrations of inorganic As but relatively little methylated As. Two contaminated paddy soils from China produced a transient peak of DMA during the early phase of incubation. Methylated As represented considerable proportions of the total soluble As in the two uncontaminated soils from the UK and US. The copy number of the microbial arsenite methyltransferase gene (arsM) correlated positively with soil pH. However, pore-water methylated As correlated negatively with pH or arsM copy number, and positively with dissolved organic C. GeoChip assay revealed considerable arsM diversity among the 6 soils, with 27 - 35 out of 66 sequences in the microarray being detected. As speciation in rice plants grown in the soils generally mirrored that in the pore water. The results suggest that methylated As species in plants originated from the soil and As methylation in soil was influenced strongly by the soil conditions.",
Arsenic,15637,"Long-term arsenic exposure and incidence of non-insulin-dependent diabetes mellitus: A cohort study in arseniasis-hyperendemic villages in Taiwan Abstract: Diabetes prevalence in arseniasis-hyperendemic villages in Taiwan has been reported to be significantly higher than in the general population. The aim of this cohort study was to further evaluate the association between ingested inorganic arsenic and the incidence of non-insulin-dependent diabetes mellitus in these villages. A total of 446 nondiabetic residents in these villages were followed biannually by oral glucose tolerance test. Diabetes is defined as a fasting plasma glucose level > or = 7.8 mmol/L and/or a 2-hr post-load glucose level > or = 11.1 mmol/L. During the follow-up period of 1499.5 person-years, 41 cases developed diabetes, showing an overall incidence of 27.4/1,000 person-years. The incidence of diabetes correlated with age, body mass index, and cumulative arsenic exposure. The multivariate-adjusted relative risks were 1.6, 2.3, and 2.1 for age > or = 55 versus < 55 years, a body mass index Greater/Equal to 25 versus < 25 kg/m(2), and a cumulative arsenic exposure > or = 17 versus < 17 mg/L-years, respectively. The incidence density ratios (95% confidence intervals) between the hyperendemic villages and the two nonendemic control townships were 3.6 (3.5-3.6), 2.3 (1.1-4.9), 4.3 (2.4-7.7), and 5.5 (2.2-13.5), respectively, for the age groups of 35-44, 45-54, 55-64, and 65-74 years. The findings are consistent with our previous cross-sectional observation that ingested inorganic arsenic is diabetogenic in human beings.",
Arsenic,95179,"A comparison of several measures of exposure to arsenic. Matched case-control study of copper smelter employees Abstract: To explore the relation between respiratory cancer mortality and exposure to airborne arsenic, methods of conditional logistic regression analysis are applied to a matched case-control study of copper smelter employees in Montana. With follow-up data for the period 1938-1977, several measures of arsenic exposure are compared. For men first employed prior to 1925, three measures--the category of maximum arsenic exposure, cumulative arsenic exposure, and time-weighted average arsenic exposure--are good predictors of respiratory cancer mortality. Within this group, there was a significantly elevated relative risk of respiratory cancer mortality associated with medium and heavy exposure to arsenic. For men first employed during 1925-1947, time-weighted average exposure to arsenic (adjusted for age at first employment) is the best predictor. In this group, men with heavy arsenic exposure and initially employed at 16.9 years had a relative risk of 6.0 in comparison to the baseline group with only light exposure to arsenic and initially employed at 31.9 years. No particular advantage is found in lagging exposures 10 years prior to death of the case in each matched set.",
Arsenic,1337503,"Cold-adapted arsenite oxidase from a psychrotolerant Polaromonas species Abstract: Polaromonas sp. str. GM1 is an aerobic, psychrotolerant, heterotrophic member of the Betaproteobacteria and is the only isolate capable of oxidising arsenite at temperatures below 10 °C. Sequencing of the aio gene cluster in GM1 revealed the presence of the aioB and aioA genes, which encode the arsenite oxidase but the regulatory genes typically found upstream of aioB in other members of the Proteobacteria were absent. The GM1 Aio was purified to homogeneity and was found to be a heterodimer. The enzyme contained Mo and Fe as cofactors and had, using the artificial electron acceptor 2,6-dichlorophenolindophenol, a K(m) for arsenite of 111.70 ± 0.88 ?M and a V(max) of 12.16 ± 0.30 U mg(-1), which is the highest reported specific activity for any known Aio. The temperature-activity profiles of the arsenite oxidases from GM1 and the mesophilic betaproteobacterium Alcaligenes faecalis were compared and showed that the GM1 Aio was more active at low temperatures than that of A. faecalis. A homology model of the GM1 Aio was made using the X-ray crystal structure of the Aio from A. faecalis as the template. Structural changes that account for cold adaptation were identified and it was found that these resulted in increased enzyme flexibility and a reduction in the hydrophobicity of the core.",
Arsenic,1704141,"Oxidation of As(III) by the bacterial community of a marine sediment monitored by microcalorimetry Abstract: Oxidation of arsenic(III) by the bacterial community of a contaminated sediment (from the Estaque marina, Marseille, France) was studied using microcalorimetry. A low, but reproducible, heat output was detectable during microbial As(III) oxidation. The heat produced was of the same order of magnitude as the heat value calculated from the standard molar enthalpy change for the As(III) oxidation by oxygen. Parameters associated with the biogeochemical cycles of arsenic, iron and carbon were studied in parallel. Amendment with arsenite delayed CO2 production and increased the rate of Fe(II) oxidation in the sediment. These results suggest a correlation between arsenic and iron biogeochemical cycles and mineralization of organic matter.",
Arsenic,1339298,"Knocking out ACR2 does not affect arsenic redox status in Arabidopsis thaliana: Implications for As detoxification and accumulation in plants Abstract: Many plant species are able to reduce arsenate to arsenite efficiently, which is an important step allowing detoxification of As through either efflux of arsenite or complexation with thiol compounds. It has been suggested that this reduction is catalyzed by ACR2, a plant homologue of the yeast arsenate reductase ScACR2. Silencing of AtACR2 was reported to result in As hyperaccumulation in the shoots of Arabidopsis thaliana. However, no information of the in vivo As speciation has been reported. Here, we investigated the effect of AtACR2 knockout or overexpression on As speciation, arsenite efflux from roots and As accumulation in shoots. T-DNA insertion lines, overexpression lines and wild-type (WT) plants were exposed to different concentrations of arsenate for different periods, and As speciation in plants and arsenite efflux were determined using HPLC-ICP-MS. There were no significant differences in As speciation between different lines, with arsenite accounting for &gt;90% of the total extractable As in both roots and shoots. Arsenite efflux to the external medium represented on average 77% of the arsenate taken up during 6 h exposure, but there were no significant differences between WT and mutants or overexpression lines. Accumulation of As in the shoots was also unaffected by AtACR2 knockout or overexpression. Additionally, after exposure to arsenate, the yeast (Saccharomyces cerevisiae) strain with ScACR2 deleted showed similar As speciation as the WT with arsenite-thiol complexes being the predominant species. Our results suggest the existence of multiple pathways of arsenate reduction in plants and yeast.",
Arsenic,627991,"Buthionine sulfoximine enhancement of arsenic trioxide-induced apoptosis in leukemia and lymphoma cells is mediated via activation of c-Jun NH2-terminal kinase and up-regulation of death receptors Abstract: The mechanism of apoptosis induced by treatment with As(2)O(3) alone or in combination with buthionine sulfoximine (BSO) was studied in NB4, U937, Namalwa, and Jurkat cells. As(2)O(3) at concentrations <2 micromol/L induced apoptosis in NB4 cells and Namalwa cells but not in U937 and Jurkat cells. As(2)O(3)-induced apoptosis in NB4 cells and Namalwa cells correlated with increase of H(2)O(2) and caspase activation without activation of c-Jun NH(2)-terminal kinase (JNK). BSO (10 micromol/L) depleted the reduced form of intracellular glutathione without inducing apoptosis but synergized with 1 micromol/L As(2)O(3) to induce apoptosis in all four cell lines. This synergy correlated with JNK activation. Treatment with As(2)O(3) plus BSO, but not with As(2)O(3) alone, increased the levels of death receptor (DR) 5 protein and caspase-8 cleavage. The JNK inhibitor SP600125 inhibited the increase in DR5 protein and attenuated apoptosis induced by treatment with As(2)O(3) plus BSO. These observations suggest that a DR-mediated pathway activated by JNK is involved in apoptosis induced by treatment with As(2)O(3) plus BSO.",1
Arsenic,1453816,"Urinary environmental chemical concentrations and vitamin D are associated with vision, hearing, and balance disorders in the elderly Abstract: BACKGROUND: Acute exposure to environmental chemicals can result in loss of consciousness and upon recovery neurological symptoms, but little evidence exists in large epidemiological human studies. Hence, it was aimed to determine the relationships between urinary environmental chemicals (including heavy metals, environmental bisphenols, pesticides, arsenic, and phthalates) concentrations and vision, hearing, and balance disorders in a national population-based setting. METHODS: United States National Health and Nutrition Examination Surveys is a national population-based multi-year cross-sectional study. Information on demographics and vision, hearing, and balance disorders was obtained by household interview using questionnaires in the 2003-2004 cohort (aged 50 and above). Urinary environmental chemicals were detected by mass spectrometry in selected but representative people. Analyses involved logistic regression models. RESULTS: Urinary cadmium, molybdenum, and tungsten concentrations, which are commonly associated with heart disease, were associated with vision disorder. Urinary 2,4,5-trichlorophenol and arsenic acid concentrations and circulating mono-n-butyl phthalate, mono-benzyl phthalate, and mono-(3-carboxypropyl) phthalate metabolites were significantly associated with hearing disorder. Moreover, urinary barium and 4-tert-octyl-phenol concentrations were associated with balance disorder. People who had ears ringing, roaring, or buzzing in the past year tended to have higher urinary barium, 2,4-dichlorophenol, and mono-benzyl phthalate concentrations. DISCUSSION: Significant correlations were observed in urinary environmental chemicals and neurobehavioural impairment for the first time. However, the causation cannot be established due to its cross-sectional study design. Future studies with a longitudinal aspect and/or in clinical trials are warranted to clearly understand the biological mechanism along the pathway before drawing a firm conclusion on these relationships.",
Arsenic,1327499,"Effects of Arsenic Compounds on Proliferation and Nitric Oxide Synthesis in C3H 10T 1/2 Murine Fibroblasts Abstract: BIOSIS COPYRIGHT: BIOL ABS. Exposure to arsenic, either through chronic consumption of contaminated water or inhalation, is associated with increased risk of cancer, yet the mechanism by which arsenicals promote neoplastic change remains undefined. The carcinogenic process involves the formation of heritable genetic changes in the DNA of normal cells and this process may be enhanced by environmental agents that increase cellular proliferation, increase DNA damage and decrease the ability to repair damage or cause immunosuppression. We describe the inhibition of cellular proliferation of C3H 10T1/2 murine fibroblasts in the presence of 1.0 muM arsenate or arsenite; yet cacodylic acid had no significant effect on cell growth in culture at this concentration. Both arsenate and cacodylate, at micromolar concentrations, slightly stimulated cell growth and cell density when cells were treated with interferon-gamma/lipopolysaccharide (IFN-gamma). At 1 muM, arsenate and cacodylate also slightly increased",
Arsenic,1579305,"The glutathione reductase GSR-1 determines stress tolerance and longevity in Caenorhabditis elegans Abstract: Glutathione (GSH) and GSH-dependent enzymes play a key role in cellular detoxification processes that enable organism to cope with various internal and environmental stressors. However, it is often not clear, which components of the complex GSH-metabolism are required for tolerance towards a certain stressor. To address this question, a small scale RNAi-screen was carried out in Caenorhabditis elegans where GSH-related genes were systematically knocked down and worms were subsequently analysed for their survival rate under sub-lethal concentrations of arsenite and the redox cycler juglone. While the knockdown of ?-glutamylcysteine synthetase led to a diminished survival rate under arsenite stress conditions, GSR-1 (glutathione reductase) was shown to be essential for survival under juglone stress conditions. gsr-1 is the sole GSR encoding gene found in C. elegans. Knockdown of GSR-1 hardly affected total glutathione levels nor reduced glutathione/glutathione disulphide (GSH/GSSG) ratio under normal laboratory conditions. Nevertheless, when GSSG recycling was impaired by gsr-1(RNAi), GSH synthesis was induced, but not vice versa. Moreover, the impact of GSSG recycling was potentiated under oxidative stress conditions, explaining the enormous effect gsr-1(RNAi) knockdown had on juglone tolerance. Accordingly, overexpression of GSR-1 was capable of increasing stress tolerance. Furthermore, expression levels of SKN-1-regulated GSR-1 also affected life span of C. elegans, emphasising the crucial role the GSH redox state plays in both processes.",
Arsenic,1936062,"Precision and accuracy of ST-EDXRF performance for As determination comparing with ICP-MS and evaluation of As deviation in the soil media Abstract: The present study was conducted to (i) determine the precision and accuracy of arsenic measurement in soil samples using ST-EDXRF by comparison with the results of ICP-MS analyses and (ii) identify the relationship of As concentration with soil characteristics. For the analysis of samples, inductively coupled plasma mass spectrometry (ICP-MS) and energy dispersive X-ray fluorescence spectrometry (EDXRF) were performed. According to the results found in the soil samples, the addition of HCl to HNO3, used for the digestion gave significant variations in the recovery of As. However, spectral interferences between peaks for As and Pb can affect detection limits and accuracy for XRF analysis. When comparing the XRF and ICP-MS results a correlation was observed with R(2)=0.8414. This means that using a ST-EDXRF spectrometer, it is possible to achieve accurate and precise analysis by the calibration of certified reference materials and choosing an appropriate secondary target. On the other hand, with regard to soil characteristics analyses, the study highlighted that As is mostly anthropogenically enriched in the studied area.",
Arsenic,1352364,"OGG1 and MYH are involved in the incision of trivalent arsenical-induced DNA adducts Abstract: Since trivalent arsenicals are known to induce oxidative DNA damage in human cells, we asked if they induce other types of DNA damage and how these DNA damages are repaired. Treatment of human promyelocytic leukemia NB4 cells with 0.5 microM As2O3 for 30 min induced no DNA breaks, as analyzed by a standard comet assay. However, breaks were detected if these cells were then digested with endonuclease III (EnIII), formamidopyrimidine-DNA glycosylase (Fpg), or a nuclear extract (NE) of NB4 cells. Using either H2O2-Fe treated nuclei or As2O3-treated cells, digestion with either NE or EnIII+Fpg generated the same amount of breaks, and subsequent treatment with EnIII+Fpg resulted in no increase in breaks in NE-digested cells and vice versa. The human cell lines, defective in nucleotide excision protein, such as XPA, XPD, and XPG, excised UVC-induced adducts less rapidly than normal fibroblasts, but excised As2O3-adducts at the same rate as the normal cells. Immunodepletion of the NE with antibody against OGG1 or MYH decreased the incision of DNA adducts induced by As2O3, NaAsO2, monomethylarsonic acid, and dimethylarsinic acid, while antibodies against XPA, XPB, XPD, XPF, or XPG, did not. These results suggest that these trivalent arsenicals induce the formation of only oxidative DNA adducts and that OGG1 and MYH are involved in these incision processes.",
Arsenic,1019643,"Exposure to polymeric materials in vascular soft-tissue sarcomas Abstract: <strong>UNLABELLED: </strong>Known etiologic factors related to endothelial angiosarcomas are exposures to arsenic, thorium dioxide, therapeutic irradiation, and certain congenital diseases. Little is known on the etiology of hemangiopericytomas. Since 1974, several reports have appeared on a distinct relationship between the exposure to vinyl chloride monomers and angiosarcomas of the liver. The early reports on this matter provided the reason to collect the occupational histories of vascular sarcomas accumulated since that time.<br /><br /><strong>METHODS: </strong>Data on the occupational histories of patients with different forms of angiosarcomas, treated between 1975 and 1995 in two institutions, were prospectively collected and analyzed. In this personal series the only selection criteria were the referral of patients for postoperative or palliative irradiation and their personal care by the author.<br /><br /><strong>FINDINGS: </strong>Among 21 adult cases of vascular sarcomas there were 4 patients with occupational exposure to vinyl chloride (VC) either alone or together with other artificial polymers. Seven other patients showed exposure to several plastics or resins other than VC. Altogether, 11 of 21 (52%) of the explored patients were found to have been exposed to artificial polymeric materials over a mean period of 18 years. The patients without such exposure were 4 farmers, 2 house-wives, and 1 woodworker, telephonist, mason, and inland revenue official, respectively. Two cases were radiation-induced. The series contained no angiosarcoma of the liver.<br /><br /><strong>INTERPRETATION: </strong>This study offers new evidence of the occurrence of vinyl-chloride-induced angiosarcomas outside the liver and confirms observations that have previously been published in case reports. Moreover, it may be suspected from this analysis that polyvinyl chloride and its monomers are not the only polymeric materials that may contribute to an induction of angiosarcomas in humans. Repeated occupational histories have to be taken from the patients to achieve data of the greatest value, since there are many professional activities that do not primarily lead to the assumption of specific exposure to polymeric materials.",
Arsenic,1240248,"Bioaccessibility and health risk of arsenic and heavy metals (Cd, Co, Cr, Cu, Ni, Pb, Zn and Mn) in TSP and PM2.5 in Nanjing, China Abstract: The bioaccessibility and human health risks of As and heavy metals (Cu, Pb, Zn, Ni, Co, Cr, Cd and Mn) in total suspended particulates (TSP) and fine particulate matter (PM2.5) in Nanjing, China were investigated. The average mass concentration ratios of PM2.5 to TSP were 0.61 for Gulou sampling site and 0.50 for Pukou sampling site, respectively. Zn, Pb, Mn and Cu were the most abundant elements among the studied metal(loid)s in both TSP and PM2.5. The results of a simple bioaccessibility extraction test of the studied metal(loid)s varied among elements, with Cd, Zn, Mn, Pb and As showing the higher bioaccessibility. The carcinogenic risks of As, Cd, Co, Cr and Ni in both TSP and PM2.5 via dermal contact and inhalation exposure were within the acceptable level (<1 × 10?4) for both children and adults, but there was potential carcinogenic risk posed by Pb via ingestion to children and adults. The hazard index values for all of the studied elements suggested no non-carcinogenic health risks via ingestion and dermal contact, but a potential non-carcinogenic health risk via inhalation to adults. Values of hazard quotient and hazard index indicated the non-carcinogenic risks from the studied metal(loid)s to children via ingestion, dermal contact and inhalation pathways in Nanjing given the present air quality.",
Arsenic,1378292,"Effect Of Arsenite On PU.1, C/EBPs, And Nfkb Activation In U937 Promonocytic Leukemia Cells Abstract: Arsenite has been reported to exert dose-dependent dual effect; triggering apoptosis at relatively high concentration, whereas it induces partial differentiation at low concentration in leukemia cells. However its bilateral character regarding the molecular mechanisms remains to be clearly defined. We examined the effect of arsenite on key transcription factors for macrophage differentiation such as PU.1 and C/EBPs to find out how arsenite interacts with the signaling pathways for differentiation in U937 promonocytic leukemia cells. Electrophoretic mobility shift assays were used to analyze the interaction between arsenite induced signaling and these transcription factors. In addition the phorbol ester TPA which activates PKCs was compared with arsenite as a second type of differentiation inducer for leukemia cells. The PU.1 activation was not changed in the presence of 1 ?M or 10 ?M arsenite for 3, 6, or 24-hrs exposure. On the other hand, activation pattern of PU.1 was drastically changed in the presence of 10 nM TPA after 24-hrs exposure. Among C/EBPs, C/EBPalpha and C/EBPepsilon were slightly affected by arsenite, but their activation were suppressed by TPA after 24-hrs exposure. NF-kappaB was constitutively activated by serum free conditions in U937 cells and this activation was suppressed by arsenite. These results indicate that arsenite and TPA interact with key regulators by different pathway in monocytic differentiation of U937 cells.",
Arsenic,711016,"Prevalence of disability in an arsenic exposure area in Inner Mongolia, China Abstract: Long term exposure to arsenic can cause adverse health effects and lead to different levels of disability. The prevalence of arsenical dermatosis is as high as 40% in the Hetao Plain area of Inner Mongolia, but the association between exposure to arsenic in drinking water and the occurrence of disability has not yet been fully examined. The aim of this study was to investigate the prevalence of disability in arsenic-affected villages in Inner Mongolia, China.<br /><br /> A cross-sectional study was performed to examine the prevalence of disability. A total of 320 villagers in the age range of 20-39 years were interviewed and examined for disability and arsenical skin lesions. The subjects were classified into a high arsenic group (50 microg L(-1)) and a low arsenic group (&lt;50 microg L(-1)). The relationship between levels of arsenic in drinking water and disability was analyzed using multivariate logistic regression models to estimate the odds ratios and 95% confidence intervals.<br /><br /> The prevalence of disability was 6.88% in the arsenic affected area of Inner Mongolia and 24.72% in the arsenic group 50 microg L(-1). A strong correlation was found between disability and arsenical skin lesions (OR=86.39, 95%CI: 25.45-293.20).<br /><br /> This suggests that the level of arsenic exposure is a major risk factor for disability. Further research is needed to place the results in a wider context and to determine the exact relationship between arsenic exposure and disability.",
Arsenic,1340197,"Arginylated calreticulin at plasma membrane increases susceptibility of cells to apoptosis Abstract: Post-translational modifications of proteins are important for the regulation of cell fate and functions; one of these post-translational modifications is arginylation. We have previously established that calreticulin (CRT), an endoplasmic reticulum resident, is also one of the arginylated substrates found in the cytoplasm. In the present study, we describe that arginylated CRT (R-CRT) binds to the cell membrane and identified its role as a preapoptotic signal. We also show that cells lacking arginyl-tRNA protein transferase are less susceptible to apoptosis than wild type cells. Under these conditions R-CRT is present on the cell membrane but at early stages is differently localized in stress granules. Moreover, cells induced to undergo apoptosis by arsenite show increased R-CRT on their cell surface. Exogenously applied R-CRT binds to the cell membrane and is able to both increase the number of cells undergoing apoptosis in wild type cells and overcome apoptosis resistance in cells lacking arginyl-tRNA protein transferase that express R-CRT on the cell surface. Thus, these results demonstrate the importance of surface R-CRT in the apoptotic response of cells, implying that post-translational arginylation of CRT can regulate its intracellular localization, cell function, and survival.",
Arsenic,1027527,"Prophylactic role of taurine on arsenic mediated oxidative renal dysfunction via MAPKs/ NF-kappaB and mitochondria dependent pathways Abstract: The present study has been designed and carried out to investigate the protective role of taurine (2-aminoethanesulphonic acid) against NaAsO(2) induced nephrotoxicity. Oral administration of arsenic increased the productions of ROS and RNS, enhanced lipid peroxidation, protein carbonylation and decreased intracellular antioxidant defence in the kidney tissue. Investigating the responsible signalling cascades, it was found that NaAsO(2) administration activates mitogen-activated protein kinases (MAPKs) and NF-kappaB in oxidative stress mediated renal dysfunction and induced apoptotic cell death by the reciprocal regulation of Bcl-2/Bad in association with reducing mitochondrial membrane potential and increased cytosolic cytochrome C as well. Treatment with taurine prior to arsenic administration effectively ameliorated As-induced oxidative renal dysfunctions and apoptotic cell death. Histological studies also support the experimental findings. Combining, results suggest that taurine possesses the ability to ameliorate arsenic-induced oxidative insult and renal damage, probably due to its antioxidant activity and functioning via MAPKs/NF-kappaB and mitochondria dependent pathways.",
Arsenic,2149178,"Unplanned Pregnancies among HIV-infected Women in Care -- United States Abstract: <strong>OBJECTIVE:: </strong>To examine the prevalence of unplanned pregnancies among HIV-infected women in care in the United States (US).<br /><br /><strong>METHODS:: </strong>We used the 2007-2008 cycles of the Medical Monitoring Project (MMP), which collected data on HIV-infected adults in care. Women were included if they had an HIV diagnosis before 45 years of age and responded to questions about pregnancies and pregnancy planning after HIV diagnosis. Logistic regression was used to calculate unadjusted and adjusted odds ratios (OR) and 95% confidence intervals (CI) for correlates of unplanned pregnancies among women with ? 1 pregnancy at or following an HIV diagnosis.<br /><br /><strong>RESULTS:: </strong>Of 1,492 women, 382 (25.6%) reported ? 1 pregnancy after HIV diagnosis (median diagnosis age = 25.0 years; interquartile range = 21.0-30.0); 58% were non-Hispanic black, 22% Hispanic and 15% non-Hispanic white. Of those, 326 (85.3%) reported ? 1 unplanned pregnancy; 124 (32.5%) reported recent unprotected vaginal and/or anal sex with a male partner with either negative or unknown HIV status. Unplanned pregnancies were more likely among women: who reported nadir CD4 cell counts &lt; 200 cells/µL (AOR = 2.3; 95% CI = 1.2-4.8) or did not report nadir CD4 cell counts (AOR = 4.3; 95% CI = 1.9-10.5) compared with women who reported nadir CD4 cell counts ? 200 cells/µL; and who received public assistance in the most recent year before MMP interview (AOR = 2.1; 95% CI = 1.1-3.8) compared with women who did not receive assistance.<br /><br /><strong>CONCLUSIONS:: </strong>Unplanned pregnancies were prevalent among our sample. To avoid unplanned pregnancies, HIV-infected women need access to effective family planning services and risk reduction discussions during routine care visits.",
Arsenic,20362,"Mutagenicity of metal salts in the L5178Y mouse lymphoma assay Abstract: In these in vitro experiments strong positive responses at cell survival rates10% were observed with CdSO[4], K[2]Cr[2]O[7] and MnCl[2]. Weak positive responses, yielding 2- to 3-fold increases in mutation frequency, occurred with HgCl[2], NaAsO[2], Na[2] HAsO[4] and Pb(NO[3])[2]. Negative responses were obtained with MgCl[2], NaCl and AlCl[3].",
Arsenic,2343546,"Environmental distribution and health impacts of As and Pb in crops and soils near Vinto smelter, Oruro, Bolivia Abstract: The Vinto Sb-Sn smelter (Oruro, Bolivia) has been linked to arsenic and heavy metal pollution in air, soils, residual waters of the smelter, and hair and urine of workers, but crop concentrations had not been assessed previously. In this article, alfalfa, onions, and carrots, separated into roots and shoots, were analyzed for As and Pb, together with corresponding soil samples. The aim was to assess the environmental distribution and potential health impacts of these toxic elements and to compare them to levels observed at other sites around the world. As and Pb concentrations in all analyzed crop samples exceed the FAO/WHO, UK or Chilean limits by 1.5-2 orders of magnitude and As health risk indices were 286 (carrot) and 651 (onion), showing that the potential health risk due to consumption of these products is extremely high. As and Pb soil-plant transfer factors are similar to other contaminated sites around the world, but daily intake and health risk index for As are much higher in Vinto area due to very high concentrations in soils. Arsenic and lead soil and crop concentrations suggest increasing trends toward VMC. Correlations are significant for Pb in some crop fractions, but not for As, possibly due to considerable geogenic contributions to soil As in the area. In future surveys, larger numbers of soil and crop samples should be analyzed, and additional analyses should be carried out to distinguish anthropogenic and geogenic sources of As and Pb in soils and crops in the area.",
Arsenic,1337318,"Highly efficient arsenic removal using a composite of ultrafine magnetite nanoparticles interlinked by silane coupling agents Abstract: Arsenic (As) contamination in groundwater is a great environmental health concern and is often the result of contact between groundwater and arsenic-containing rocks or sediments and from variation of pH and redox potentials in the subsurface. In the past decade, magnetite nanoparticles (MNPs) have been shown to have high adsorption activity towards As. Alerted by the reported cytotoxicity of 5–12 nm MNP, we studied the adsorption behavior of 1.15 nm MNP and a MNP composite (MNPC), MNPs interlinked by silane coupling agents. With an initial concentration of As at 25 mg L?1, MNPs exhibited high adsorption capacity for As(V) and As (III), 206.9 mg·g?1 and 168.6 mg·g?1 under anaerobic conditions, respectively, and 109.9 mg·g?1 and 108.6 mg·g?1 under aerobic conditions, respectively. Under aerobic conditions, MNPC achieved even higher adsorption capacity than MNP, 165.1 mg·g?1 on As(V) and 157.9 mg·g?1 on As(III). For As(V) at 50 mg L?1, MNPC achieved an adsorption capacity as high as 341.8 mg·g?1, the highest in the literature. A kinetic study indicated that this adsorption reaction can reach equilibrium within 15 min and the rate constant of As(V) is about 1.9 times higher than that of As(III). These results suggested that MNPC can serve as a highly effective adsorbent for fast removal of As.",
Arsenic,2278494,"Changes in microbial biomass, CH4 and CO2 emissions, and soil carbon content by fly ash co-applied with organic inputs with contrasting substrate quality under changing water regimes Abstract: Application of fine-textured and Ca-rich fly ash may be helpful in enhancing soil carbon content via protecting soil organic C (SOC) by organo-mineral complexation and via reducing CO2 emission by carbonation (e.g. formation of CaCO3). However, very limited information is available on the effects of fly ash application on gases loss of C and soil C content. In this study, to estimate the potential use of fly ash as a soil amendment for SOC enhancement purposes, the effects of fly ash application (0, 5, and 10 w/w %) on microbial biomass C (MBC), CH4 and CO2 emissions, and on soil C content were investigated. A 60-days incubation experiment was conducted with an acidic soil in the presence of organic input (pig manure compost, PMC; hairy vetch, HV) with contrasting substrate quality under changing water regime from water-logged to unsaturated via a transition period. Fly ash application did not affect MBC under water-unsaturated conditions, but reduced (P &lt; 0.01) microbial growth under water-logged conditions, probably due to the increased solubility of a certain toxic element such as arsenic under the anaerobic conditions. Across the 60 days of incubation, the CO2 emission was reduced by fly ash regardless of organic input by 20.5-41.3%; meanwhile, a decline of CH4 emission by fly ash application was significant (P &lt; 0.05) only in the HV treatment. Overall, fly ash application slowed down gases C loss and increased soil C content, probably due to the retardation of CH4 and CO2 emission as well as the addition of C contained in the fly ash. Biochemical (inhibition of microbial activity), chemical (formation of CaCO3 via carbonation), and physical (restriction of gas diffusion) mechanisms were suggested for the fly ash effects. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,1032280,"Effect of amino acid analogs on the development of thermotolerance and on thermotolerant cells Abstract: Exposure of HA-1 Chinese hamster fibroblasts to amino acid analogs has been shown to have a heat-sensitizing effect as well as inducing the heat shock response (Li and Laszlo, 1985a). In this study, we have examined the effect of amino acid analogs on the development of thermotolerance after a brief heat shock or exposure to sodium arsenite and the effect of amino acid analogs on cells that are already thermotolerant. Exposure of HA-1 cells to amino acid analogs inhibited the development of thermotolerance following a mild heat shock or treatment with sodium arsenite. However, cells that were already thermotolerant were resistant to the sensitizing action of amino acid analogs. The refractoriness of thermotolerant cells to amino acid analog treatment developed in parallel with thermotolerance. The uptake of the arginine analog, canavanine, and its incorporation into proteins was not altered in the thermotolerant cells. Furthermore, another biological consequence of exposure to amino acid analogs, sensitization to ionizing radiation, also was not altered in the thermotolerant cells. The inhibition of the development of thermotolerance by amino acid analogs and the refractoriness of thermotolerant cells to the heat-sensitizing action of amino acid analogs lend further support the role of heat-shock proteins in the phenomenon of thermotolerance.",
Arsenic,1027673,"Multiple risk factors associated with arsenic-induced skin cancer: Effects of chronic liver disease and malnutritional status Abstract: In order to evaluate the prevalence and multiple risk factors of arsenic-induced skin cancer among residents in Taiwanese villages in which chronic arseniasis is hyperendemic, a total of 1571 subjects aged 30 or more years were recruited between September 1988 and March 1989. All of them were interviewed personally by a public health nurse using a structured questionnaire, and 1081 interviewed study subjects, including 468 men and 613 women, participated in physical examination, giving a participation rate of 68.8%. The overall prevalence of skin cancer was as high as 6.1%, showing an increase with age in both men and women. There was a significant dose-response relation between skin cancer prevalence and chronic arsenic exposure as indexed by duration of residence in the endemic area, duration of consumption of high-arsenic artesian well water, average arsenic exposure in parts per million (p.p.m.) and cumulative arsenic exposure in p.p.m.-years. Chronic carriers of hepatitis B surface antigen with liver dysfunction had an increased prevalence of skin cancer. Undernourishment, indexed by a high consumption of dried sweet potato as a staple food, was also significantly associated with an increased prevalence of arsenic-induced skin cancer. All these risk factors remained statistically significant in the multiple logistic regression analysis. Consistent with animal experiments, the findings imply that liver function and nutritional status may affect the metabolism of inorganic arsenic and the development of subsequent skin cancers.",
Arsenic,112480,"Gene expression profiling of responses to dimethylarsinic acid in female F344 rat urothelium Abstract: Gene expression profiling has been shown to be useful for identifying underlying mechanisms of toxicity, determining patterns of biological response, and elucidating candidate markers of exposure and response. Inorganic arsenic (iAs) is a human carcinogen and epidemiologic evidence implicates it in the development of urinary bladder cancer. Dimethylarsinic acid (DMA), the major excreted metabolite of iAs in humans, is a known rat bladder carcinogen. To examine the changes associated with DMA exposure, microarray analysis of the urothelium was performed in female F344 rats exposed to non-toxic and toxic doses of DMA in their drinking water for 28 days. A novel method for isolating predominantly urothelial cells was developed. Gene expression profiling of the urothelium using a custom 2-dye spotted array revealed that DMA treatment modulated the expression of transcripts of genes that regulate apoptosis, cell cycle regulation and the oxidative stress response. Expression of genes mapping to pathways involved in cancer control processes were also altered after DMA exposure. Morphological data suggested a dose dependent increase in cellular toxicity. Significant changes in differential gene expression were present after all treatments event at doses where standard toxicological responses were not detectable. The greatest perturbation in gene expression was present in rats after treatment with 40 ppm DMA. Doses which produced no histologic or ultrastructural evidence of toxicity (non-toxic) could be differentiated from toxic doses based on the expression of a subset of genes, which control cell signaling and the stress response. These reported changes in gene expression show similarities between the mechanisms of action of DMA in vivo and those previously described for iAs in vitro. These data illustrate the utility of transcriptional profiling and its potential in predicting key mechanistic pathways involved in toxicity and as a time efficient tool to inform the mode of action analysis in risk assessment.",
Arsenic,1024337,"Novel thioarsenic metabolites in human urine after ingestion of an arsenosugar, 2',3'-dihydroxypropyl 5-deoxy-5-dimethylarsinoyl-beta-D-riboside Abstract: The presence of arsenic-containing carbohydrates, arsenosugars, in many seafoods raises questions of human health concerning the ingestion and metabolism of these compounds. A previous study investigating the metabolites in human urine after the ingestion of a common arsenosugar 2',3'-dihydroxypropyl 5-deoxy-5-dimethylarsinoyl-beta-d-riboside (oxo-arsenosugar) showed that the arsenic was rapidly excreted in the urine and was present as at least 12 metabolites, only three of which could be identified. In this repeat study with oxo-arsenosugar and using high-performance liquid chromatography/inductively coupled plasma mass spectrometry, we report the identification of seven arsenic metabolites, which together accounted for 88% of the total urinary arsenic collected over 61 h. The metabolites included previously reported human urinary arsenicals dimethylarsinate (DMA), oxo-dimethylarsenoethanol (oxo-DMAE), and trimethylarsine oxide, in addition to new human metabolites oxo-dimethylarsenoacetate (oxo-DMAA), thio-dimethlyarsenoacetate (thio-DMAA), thio-dimethylarsenoethanol (thio-DMAE), and the thio-arsenosugar. Cytotoxicity testing of the major metabolites DMA, oxo-DMAE, thio-DMAE, oxo-DMAA, and thio-DMAA showed that they were nontoxic even at 10 mM, except for DMA, which showed some toxic effects at 1 mM.",
Arsenic,1029493,"Cultured rat embryo accumulation of DNA, RNA, and protein following maternal administration of sodium arsenate Abstract: HEEP COPYRIGHT: BIOL ABS. The effects on embryonic development of a number of metal and metal-like elements found in the environment are interesting because of their teratogenic potential. Whole embryo culture techniques were used to test the effects of sodium arsenate on the rates of DNA, RNA and protein accumulation. Rat embryos were isolated on the 10th gestational day (sperm day = day 0) either 4 or 24 h after maternal injection. The cultivation period was for 24 or 42 h. DNA, RNA and protein values were not significantly different for in utero treatment 4 h prior to dissection. For embryos treated in utero 24 h prior to dissection, DNA, RNA and protein levels were significantly lower at the beginning of cultivation and after 24 h in culture. By 42 h, DNA and RNA values were still significantly reduced. A number of morphologic differences were also noted following cultivation for embryos treated in utero 24 h prior to dissection. These include a significant number of embryos failing to rotate to a ventroflexed position, have a closed anterior neuropore, establish a visceral yolk sac circulation, and fuse the allantoic sac in placental formation. Sodium arsenate takes longer than 4 h to affect the embryo. A 24-h in utero exposure is adequate to initiate teratogenic responses. The abnormal persistence of a definitive allantoic sac after culture may be indicative of abnormalities in urogenital system formation. Effects of sodium arsenate seem to be related to proliferative embryonic cell requirements with some insult recovery of the embryo possible.",
Arsenic,2064256,"Association of low to moderate levels of arsenic exposure with risk of type 2 diabetes in Bangladesh Abstract: Chronic exposure to high levels of arsenic in drinking water is associated with increased risk of type 2 diabetes mellitus (T2DM), but the association between lower levels of arsenic and T2DM is more controversial. Therefore, this study evaluated the association between low to moderate arsenic exposure and T2DM. In 2009-2011, we conducted a study of 957 Bangladeshi adults who participated in a case-control study of skin lesions in 2001-2003. The odds ratio of T2DM was evaluated in relationship to arsenic exposure measured in drinking water and in subjects' toenails (in 2001-2003) prior to the diagnosis of T2DM (in 2009-2011). Compared with those exposed to the lowest quartile of arsenic in water (?1.7 µg/L), the adjusted odds ratio for T2DM was 1.92 (95% confidence interval (CI): 0.82, 4.35) for those in the second quartile, 3.07 (95% CI: 1.38, 6.85) for those in the third quartile, and 4.51 (95% CI: 2.01, 10.09) for those in the fourth quartile. The relative excess risk of T2DM was 4.78 for individuals who smoked and 8.93 for people who had a body mass index (weight (kg)/height (m)(2)) greater than 25. These findings suggest that exposure to modest levels of arsenic in drinking water was associated with increased risk of T2DM in Bangladesh. Being overweight or smoking was also associated with increased risk of T2DM.",
Arsenic,1509336,"Recent advances in speciation analysis of mercury, arsenic and selenium Abstract: ",
Arsenic,1337518,"Hazardous impact of organic arsenical compounds in chicken feed on different tissues of broiler chicken and manure Abstract: The purpose of this study was to evaluate the translocation of arsenic (As) from feed to different tissues of broiler chicken (leg, breast, liver and heart) and excretory product (manure). The feed, broiler chicken and manure samples were collected from five selected poultry farms. The As concentrations in all samples were determined by electrothermal atomic absorption spectrometry, after microwave assisted acid digestion in closed vessels. The concentrations of As in different chicken feeds were found in the range of 21.3-43.7?gg(-1). The contents of As in different tissues of broiler chicken, liver, muscles and heart were found in the range of 3.07-7.17, 2.15-5.28 and 2.11-6.36?gg(-1), respectively, while manure samples contains 22.8-50.3?gg(-1). The obtained data shows the high correlation coefficient between As contents in feed, excretory product or manure and tissues of broiler chicken in the range of r=0.41-0.83. The high level of As in excretory product may add toxicant to environment, on their disposal.",
Arsenic,1355021,"ELEVATED LEVELS OF ARSENIC AND FLUORIDE, BUT NOT SELENIUM, ASSOCIATED WITH ENDEMIC DISEASE IN THE CHINESE VILLAGE OF DAZHUYUAN, SHAANXI PROVINCE Abstract: ",
Arsenic,627234,"Speciation of key arsenic metabolic intermediates in human urine Abstract: Biomethylation is the major human metabolic pathway for inorganic arsenic, and the speciation of arsenic metabolites is essential to a better understanding of arsenic metabolism and health effects. Here we describe a technique for the speciation of arsenic in human urine and demonstrate its application to the discovery of key arsenic metabolic intermediates, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), in human urine. The study provides a direct evidence in support of the proposed arsenic methylation pathway in the human. The finding of MMAIII and DMAIII in human urine, along with recent studies showing the high toxicity of these arsenicals, suggests that the usual belief of arsenic detoxification by methylation needs to be reconsidered. The arsenic speciation technique is based on ion pair chromatographic separation of arsenic species on a 3-micron particle size column at 50 degrees C followed by hydride generation atomic fluorescence detection. Speciation of MMAIII, DMAIII, arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) in urine samples is complete in 6 min with detection limits of 0.5-2 micrograms/L. There is no need for any sample pretreatment. The capability of rapid analysis of trace levels of arsenic species, which resulted in the findings of the key metabolic intermediates, makes the technique useful for routine arsenic speciation analysis required for toxicological and epidemiological studies.",
Arsenic,711003,"p52-Bcl3 complex promotes cyclin D1 expression in BEAS-2B cells in response to low concentration arsenite Abstract: Arsenic is a well-recognized human carcinogen that causes a number of malignant diseases, including lung cancer. Previous studies have indicated that cyclin D1 is frequently over-expressed in many cancer types. It is also known that arsenite exposure enhances cyclin D1 expression, which involves NF-kappaB activation. However, the mechanism between cyclin D1 and the NF-kappaB pathway has not been well studied. This study was designed to characterize the underlying mechanism of induced cell growth and cyclin D1 expression in response to low concentration sodium arsenic (NaAsO(2)) exposure through the NF-kappaB pathway. Cultured human bronchial epithelial cells, BEAS-2B, were exposed to low concentration sodium arsenite for the indicated durations, and cytotoxicity, gene expression, and protein activity were assessed. To profile the canonical and non-canonical NF-kappaB pathways involved in cell growth and cyclin D1 expression induced by low concentration arsenite, the NF-kappaB-specific inhibitor-phenethyl caffeate (CAPE) and NF-kappaB2 mRNA target sequences were used, and cyclin D1 expression in BEAS-2B cells was assessed. Our results demonstrated that exposure to low concentration arsenite enhanced BEAS-2B cells growth and cyclin D1 mRNA and protein expression. Activation and nuclear localization of p52 and Bcl3 in response to low concentration arsenite indicated that the non-canonical NF-kappaB pathway was involved in arsenite-induced cyclin D1 expression. Moreover, we further demonstrated that p52/Bcl3 complex formation enhanced cyclin D1 expression through the cyclin D1 gene promoter via its kappaB site. The up-regulation of cyclin D1 mediated by the p52-Bcl3 complex in response to low concentration arsenite might be important in assessing the health risk of low concentration arsenite and understanding the mechanisms of the harmful effects of arsenite.",
Arsenic,1032988,Reduction in heat shock gene expression correlates with increased thermosensitivity in senescent human fibroblasts Abstract: The expression of three major classes of heat shock genes was examined in human diploid cells at differing in vitro ages. Metabolic labeling of cellular proteins following a brief heat shock showed that the synthesis of heat shock proteins was significantly reduced in late-passage cells. Northern blot analyses revealed that the reduced expression of heat shock proteins in old cells correlated with a reduced accumulation of heat shock-specific transcripts. The attenuation of heat shock gene activity in senescent cells was not unique to thermal stress since exposure of cells to sodium arsenite (10-50 microM) elicited a similar response. The reduced expression of heat shock gene products correlated with an increased thermal lability in late-passage cells following acute hyperthermic (49 degrees C) exposure. The preinduction of heat shock genes protected cells against the lethal effects of acute hyperthermia and abolished the increased thermal lability observed in senescent cells. The reduced expression of the heat shock response demonstrates that old cells possess a diminished ability to withstand adverse environmental conditions and maintain homeostasis.,
Arsenic,1936154,"Dependence of arsenic fate and transport on biogeochemical heterogeneity arising from the physical structure of soils and sediments Abstract: Reduction of As(V) and Fe(III) is commonly the dominant process controlling the fate and transport of As in soils and sediments. However, the physical structure of such environments produces complex heterogeneity in biogeochemical processes controlling the fate and transport of As. To resolve the role of soil and sediment physical structure on the distribution of biogeochemical processes controlling the fate and transport of As, we examined the biogeochemical transformations of As and Fe within constructed aggregates—a fundamental unit of soil structure. Spherical aggregates were made with As(V)- or As(III)-bearing, ferrihydrite-coated quartz that was fused with agarose and placed in a cylindrical reactor; advective flow of anoxic solutes was then initiated around the aggregates to examine As release from a dual-pore domain system. To examine the impact of biotic As(V) and Fe(III) reduction, constructed aggregates having As(V)-bearing, ferrihydrite-coated quartz inoculated with Shewanella sp. ANA-3 were placed in flow-through reactors under anoxic and aerated advective flow. Consistent with desorption from advective columns, As(III) is released to advecting water more prevalently than As(V) within abiotic aggregate systems, indicating a greater lability and concomitant enhanced propensity for transport of As(III) relative to As(V). During reaction with Shewanella, As release to advecting water was similar between anoxic and aerated systems for the first 20 d; thereafter, the anoxic advecting solutes increased As release relative to the aerated counterpart. With aerated advecting solutes, Fe remained oxidized (or was oxidized) in the aggregate exterior, forming a protective barrier that limited As release to the advective channel. However, anaerobiosis within the aggregate interior, even with aerated advective flow, promotes internal repartitioning of As to the exterior region.",
Arsenic,1376483,"Spontaneous high expression of heat-shock proteins in mouse embryonal carcinoma cells and ectoderm from day 8 mouse embryo Abstract: When submitted to a heat-shock, mouse embryonal carcinoma (EC) and fibroblast cells show very different behavior. All the EC cells so far analyzed express very high levels of several heat-shock proteins (HSP) in the absence of stress and independent of their origin and culture conditions. In such cells, the 89-kd, 70-kd and 59-kd HSP are the most prominent proteins after actin. In addition, the 89-kd and 59-kd HSP are not stimulated by an arsenite shock in contrast to what is observed with fibroblasts or cells of the parietal yolk sac type. Arsenite induces the synthesis of a 105-kd polypeptide in fibroblasts but not in EC cells. In vitro differentiation of F9 cells induced by retinoic acid and dibutyryl cAMP is accompanied by a decrease in the spontaneous relative abundance of HSP and restores the arsenite-induced synthesis of the 105-kd polypeptide. EC cells are usually believed to be similar to inner cell mass cells of mouse blastocyst. Furthermore, data in the literature together with our own results suggest that the same three HSP are also spontaneously expressed in high amounts in the early mouse embryo.",
Arsenic,627592,"Arsenic-induced cell death in liver and brain of experimental rats Abstract: Arsenic is a well established human carcinogen and is ubiquitous in the environment. The present study demonstrates the effect of acute arsenic administration at three different doses in liver and brain of Wistar rats. Sodium arsenite was administered orally at doses of 6.3 mg/kg, 10.5 mg/kg and 12.6 mg/kg of body weight on the basis of a lethal dose 50% (LD50) for 24 hr. After administration of arsenites, liver and brain were analyzed for various parameters of oxidative stress, histopathological changes and caspase-3 activity. Glutathione levels were decreased significantly in the liver at all doses. In liver the following biochemical changes were observed, a significant lipid peroxidation and cytochrome-P450 induction along with significant decrease in catalase and superoxide dismutase was observed at 10.5 mg/kg and 12.6 mg/kg. The activity of glutathione peroxidase was increased significantly at all doses. In brain, no significant change was observed at 6.3 mg/kg. However, a significant increase in lipid peroxidation and glutathione peroxidase activity along with significant decrease in the activity of glutathione, catalase and superoxide dismutase was observed at 10.5 mg/kg and 12.6 mg/kg. The activity of glutathione-S-transferase was decreased significantly in both liver and brain at 10.5 and 12.6 mg/kg. No significant alteration in the activity of glucose-6-phosphate dehydrogenase and glutathione reductase was observed in either liver or brain at any dose. Dose-dependent histopathological changes, observed in both liver and brain are also described. A significant increase in caspase-3 activity was observed at all doses in liver and at 10.5 and 12.6 mg/kg in brain. Sodium arsenite caused DNA cleavage into fragments and manifested as ""DNA laddering"", a hallmark of apoptosis.",
Arsenic,1346505,"Direct cardiotoxicity from an acute pentavalent arsenic ingestion Abstract: Background: Inorganic trivalent (TA) and pentavalent arsenic (PA), are interconverted in vivo. TA binds to sulfhydryl groups and inhibits glycolysis and the Kreb’s cycle. PA replaces phosphate in ATP and uncouples oxidative phosphorylation, and arsenic can produce oxygen free radicals. Acute arsenic cardiotoxicity is commonly manifested as dysrhythmias. We present a case with evidence of both dysrhythmia and direct myocardial ischemia from PA. Case report: A 57 yo healthy male intentionally ingested 3 grams of granular PA and presented to the emergency department 6.5 hours later with nausea, hematemesis and abdominal pain. His initial ECG showed ST depression in leads II, III, and aVF with hyperacute T waves in leads V2-V5. After transfer to a tertiary center 9 hours post ingestion, his blood pressure was 117/56 mm Hg, heart rate 100 bpm, ECG had ST depression in leads V3-V6 with a QTc of 610 ms, and the troponin I was 0.51 ng/mL. The troponin I continued to rise to 6.81 ng/mL at 19 hrs and 17.49 ng/mL at 27 hrs post ingestion. The patient was treated with IV fluid boluses, gastric lavage, endoscopy, dimercaprol, mechanical ventilation, vasopressors and continuous venovenous hemofiltration. The patient died approximately 32 hours post-ingestion from multisystem organ failure. His 8 hour post-ingestion urinary inorganic arsenic concentration was 264 mg/L. Discussion: A variety of ECG findings may be seen with acute arsenic poisoning including conduction blocks, QT interval prolongation, T wave changes, as well as ventricular tachycardia and fibrillation. Cardiovascular complications and cardiomyopathy have been described after chronic arsenic exposure. CoInclusion: This case of acute PA toxicity demonstrated early laboratory and ECG signs of cardiac ischemia before refractory hypotension and multi-system organ failure developed. These findings suggest that acute cardiac ischemia may result from acute PA induced reduction in myocardial ATP production, and free radical generation.",
Arsenic,1519038,"The metalloid arsenite induces nuclear export of Id3 possibly via binding to the N-terminal cysteine residues Abstract: Ids are versatile transcriptional repressors that regulate cell proliferation and differentiation, and appropriate subcellular localization of the Id proteins is important for their functions. We previously identified distinct functional nuclear export signals (NESs) in Id1 and Id2, but no active NES has been reported in Id3. In this study, we found that treatment with the stress-inducing metalloid arsenite led to the accumulation of GFP-tagged Id3 in the cytoplasm. Cytoplasmic accumulation was impaired by a mutation in the Id3 NES-like sequence resembling the Id1 NES, located at the end of the HLH domain. It was also blocked by co-treatment with the CRM1-specific nuclear export inhibitor leptomycin B (LMB), but not with the inhibitors for mitogen-activated protein kinases (MAPKs). Importantly, we showed that the closely spaced N-terminal cysteine residues of Id3 interacted with the arsenic derivative phenylarsine oxide (PAO) and were essential for the arsenite-induced cytoplasmic accumulation, suggesting that arsenite induces the CRM1-dependent nuclear export of Id3 via binding to the N-terminal cysteines. Finally, we demonstrated that Id3 significantly repressed arsenite-stimulated transcription of the immediate-early gene Egr-1 and that this repression activity was inversely correlated with the arsenite-induced nuclear export. Our results imply that Id3 may be involved in the biological action of arsenite.",
Arsenic,628474,"Effects of arsenic exposure and genetic polymorphisms of p53, glutathione S-transferase M1, T1, and P1 on the risk of carotid atherosclerosis in Taiwan Abstract: To evaluate the joint effects between genetic polymorphisms of glutathione S-transferase M1, T1, P1, and p53, and arsenic exposure through drinking well water on the risk of carotid atherosclerosis, 605 residents including 289 men and 316 women were recruited from a northeastern area of Taiwan. Carotid atherosclerosis was diagnosed by either a carotid artery intima-media thickness (IMT) of >1.0 mm, a plaque score of > or =1, or stenosis of >50%. A significant age- and gender-adjusted odds ratio of 3.3 for the development of carotid atherosclerosis was observed among the high-arsenic exposure group who drank well water containing arsenic at levels >50 microg/L. The high-arsenic exposure group with GSTP1 variant genotypes of Ile/Val and Val/Val, and with the p53 variant genotypes of Arg/Pro and Pro/Pro had 6.0- and 3.1-fold higher risks of carotid atherosclerosis, respectively. In addition, the high-arsenic exposure group with one or two variant genotypes of GSTP1 and p53 had 2.8- and 6.1-fold higher risks of carotid atherosclerosis, respectively, and showed a dose-dependent relationship. A multivariate-adjusted odds ratio of 3.4 for the risk of carotid atherosclerosis among study subjects with the two variant genotypes of GSTP1 and p53 was also found. Our study showed the joint effects on the risk of carotid atherosclerosis between the genetic polymorphisms of GSTP1 and p53, and arsenic exposure.",
Arsenic,1797788,"Prediction of cadmium concentration in selected home-produced vegetables Abstract: Soil contaminated with cadmium presents a potential hazard for humans, animals and plants. The latter play a major role in the transfer of cadmium to the food chain. The uptake of cadmium and its accumulation by plants is dependent on various soil, plants and environmental factors. In order to identify soil properties with statistically significant influence on cadmium concentration in vegetables and to reduce the collection of data, time and costs, regression models can be applied. The main objective of this research was to develop regression models to predict the concentration of cadmium in 9-vegetable species: zucchini, tomato, cabbage, onion, potato, carrot, red beet, endive and chicory, based on soil properties. Soil samples were collected from 123 home gardens of the Municipality of Celje and 59 of these gardens were also included in vegetable sampling. The concentration of elements (e.g. arsenic, cadmium, copper, lead, and zinc) in the samples was determined by Inductively Coupled Plasma Mass Spectrometry. Single (for cabbage, potato, red beet and chicory) and multiple (for tomato, onion, carrot and endive) linear regression models were developed. There was no statistically significant regression model for zucchini. The most significant parameter for the influencing the cadmium concentration in vegetables was the concentration of cadmium in soil. Other important soil properties were the content of organic matter, pH-value and the concentration of manganese. It was concluded that consuming carrots, red beets, endives, onions, potatoes and chicory which are grown in gardens with Cd concentrations (mgkg(-1) DW) above 2.4, 3.2, 6.3, 7.9, 8.3 and 10.9, respectively, might represent an important contribution to dietary Cd exposure.",
Arsenic,1579375,What could arsenic bacteria teach us about life? Abstract: ,
Arsenic,1356596,"Effect of arsenite on certain aspects of protein metabolism in fresh water teleost, Tilapia mossambica (Peters) Abstract: The sublethal toxicity of sodium arsenite on protein metabolism was investigated in teleost fish, Tilalpia mossambica at the end of 24, 48, 72 and 96 h of exposure. Total protein content, free amino acid content and activities of the enzymes aspartate amino transferase (AAT) and alanine amino transferase (ALAT) in liver, gill, brain and muscle exhibited significant (P&lt;0.05) alterations throughout the investigation in relation to that of control. It is suggested that the fish is able to respond to the stressful situations by gearing up the metabolic activity as revealed by the elevated protein, amino acid content and the activities of AAT and ALAT.",
Arsenic,2149104,"Arsenic ecotoxicology: The interface between geosphere, hydrosphere and biosphere Abstract: ",
Arsenic,1378219,"P53 Modulates Arsenite-Induced Mitotic Disruption And Altered Gene Expression Abstract: Arsenic is both a carcinogen and an efficacious chemotherapeutic for acute promyelocytic leukemia. The underlying mechanism of arsenic-induced carcinogenesis or chemotherapy is unknown. Arsenic disrupts mitosis, induces mitotic delay, and alters chromosome segregation. Our data suggest p53 status is a determinant in response to mitotic disruption by arsenic. Arsenic-treated p53 deficient cells are prone to mitotic arrest associated apoptosis (MAAA). P53 wt cells are more resistant to MAAA and survive an aberrant, aneuploidogenic mitosis. To examine how p53 status impacts mitotic entry and exit in arsenic-treated cells, we used TR9-7 cells which express p53 from a tet-off regulated vector. TR9-7 cells expressing (p53+) or not expressing (p53-) p53 were synchronized in G2 and released with or without 5 uM NaAsO2. Arsenite delayed mitotic entry independent of p53. Arsenite-treated p53+ cells exited mitosis normally, while treated p53- cells had delayed kinetics. To test if differential gene expression altered exit kinetics, microarray analysis was performed on mRNAs from G2 synchronized p53+ and p53- cells after 0 and 3 h arsenite exposure. Heme oxygenase and metallothionein, two oxidative stress response genes, were induced independent of p53 status. Inhibitor of DNA binding 1 (ID1) was induced 6.9-fold in p53+ cells and 4.3-fold in p53- cells. Immunoblotting confirmed induction that was more extensive and sustained in p53+ cells. As a dominant negative inhibitor of transcription, ID1 represses genes involved in cell cycle arrest. ID1 is elevated in many tumors and its overexpression immortalizes primary human keratinocytes and induces abnormal centrosome numbers. ID1 induction may play a role in the survival of arsenite-treated p53+ cells and contribute to the carcinogenicity of arsenic.",
Arsenic,2347807,"Efficient removal of arsenic (V) from water using steel-making slag Abstract: This study describes the potential use of steel-making slag as an arsenic-removal medium. Systematic analysis of slag material revealed a composition of oxides of calcium, iron, silicon, and phosphorous. Under the experimental conditions of this study, the equilibrium time was shown to be 2 hours, and the removal capacity to be 99%, with an adsorbent loading capacity of 1.25g/l. The adsorption kinetics were shown to follow a pseudo-second-order rate equation, and the adsorption isotherm closely followed both the Langmuir and Freundlich isothermic models. Variations in solution pH levels demonstrated that with a decrease in the initial solution pH, the adsorption capacity decreases. This is attributed to the leaching of silica and phosphate from the slag to the solution, which imparted a competing effect for adsorption sites. However, with an alkaline pH, such leaching was reduced, and due to formation of calcium carbonate from the leached calcium from the slag material, the arsenic removal efficiency increased as it was co-precipitated with calcium carbonate.",
Arsenic,1519225,"Bacterial mechanisms of reversible protein S-thiolation: Structural and mechanistic insights into mycoredoxins Abstract: Mycobacteria produce millimolar concentrations of mycothiol (MSH) as their major low molecular weight thiol redox buffer. MSH-deficient mutants display increased sensitivity towards reactive oxygen, nitrogen and electrophilic species as well as alkylating agents and antibiotics. MSH is maintained in its reduced thiol state by the NADPH-dependent mycothiol disulphide reductase (Mtr). However, the redoxin that uses the MSH/Mtr/NADPH pathway for reduction of MSH-mixed protein disulphides, formed during oxidative stress, has long remained unknown. In this issue, Van Laer et?al. report that MSH provides the reducing power for mycoredoxin-1 (Mrx1) in reduction of synthetic MSH-mixed disulphides. The reduced (dithiol) and oxidized (disulphide) solution structures of Mrx1 have been solved by nuclear magnetic resonance (NMR) spectroscopy. NMR time course experiments have also demonstrated the transient S-mycothiolation of the active site Cys14 of oxidized Mrx1 during reduction by the MSH/Mtr/NADPH electron pathway. The paper opens a new era of research to identify S-mycothiolated Mrx1 substrates and the function of MSH in redox regulation and virulence in Mycobacterium tuberculosis.",
Arsenic,1022086,"Elevated risk of hypertension induced by arsenic exposure in Taiwanese rural residents: Possible effects of manganese superoxide dismutase (MnSOD) and 8-oxoguanine DNA glycosylase (OGG1) genes Abstract: Heavy metals, including arsenic and lead, may lead to cellular oxidative damage that is linked to hypertension. Manganese superoxide dismutase (MnSOD) is a scavenger of reactive oxygen species, and 8-oxoguanine DNA glycosylase (OGG1) is the major glycosylase that repairs DNA lesions. Interestingly, whether there is an elevated risk of hypertension with arsenic or lead exposure in individuals with genetic variations in MnSOD or OGG1 has not yet been investigated. Questionnaires were administered to 240 Taiwanese rural residents. Blood pressure and biochemical indicators were assessed in each subject. Urinary levels of arsenic and lead were measured with atomic absorption spectrometry; and MnSOD and OGG1 genotypes were identified via polymerase chain reaction. There was a dose-response relationship between urinary arsenic levels and risk of hypertension (P = 0.021, test for trend). However, there was no association between urinary lead levels and hypertension risk. Individuals with high urinary arsenic levels and the MnSOD Val-Ala/Ala-Ala genotypes had a greater risk of hypertension than those with low urinary arsenic levels and the MnSOD Val-Val genotype (odds ratio [OR] = 4.2, 95% confidence interval [CI] = 1.7-10.3). Subjects with a high urinary arsenic level and the OGG1 Cys-Cys genotype also had a greater risk of hypertension than those with a low urinary arsenic level and the OGG1 Ser-Ser/Ser-Cys genotypes (OR = 3.4, 95% CI = 1.1-10.7). Thus, both MnSOD and OGG1 genotypes may be prone to an increased risk of hypertension associated with arsenic exposure.",
Arsenic,2337065,"Asymmetric synthesis of P-stereogenic diarylphosphinites by palladium-catalyzed enantioselective addition of diarylphosphines to benzoquinones Abstract: The reaction of phenyl(2,4,6-trimethylphenyl)phosphine with a substituted benzoquinone in the presence of a chiral phosphapalladacycle complex as a catalyst and triethylamine in chloroform at -45 degrees C proceeded in a new type of addition manner to give a high yield of a 4-hydroxyphenyl phenyl(2,4,6-trimethylphenyl)phosphinite with 98% enantioselectivity, which is a versatile intermediate readily convertible into various phosphines and their derivatives with high enantiomeric purity.",
Arsenic,627824,"Arsenic exposure exacerbates atherosclerotic plaque formation and increases nitrotyrosine and leukotriene biosynthesis Abstract: A correlation between arsenic and cardiovascular disease (CVD) has been established through epidemiological studies, although the mechanisms are unknown. Using a mouse model that develops atherosclerotic lesions on a normal chow diet, we have confirmed a connection between long-term arsenic intake and CVD. Our results reveal a significant increase in the degree of atherosclerotic plaque stenosis within the innominate artery of ApoE-/-/LDLr-/- mice treated with 10 ppm sodium arsenite (133 ?M) in drinking water for 18 weeks compared to controls. Immunohistochemistry shows nitrotyrosine formation, a marker of reactive nitrogen species generation, is significantly higher within the atherosclerotic plaque of arsenic-treated mice. In addition, there is a significant increase in the 5-lipoxygenase (5-LO) product, leukotriene E4 (LTE4), in the serum of arsenic-treated mice. This is supported by induction of the 5-LO protein and subsequent increases in LTE4 synthesis in bovine aortic endothelial cells. This increase in LTE4 is partially inhibited by inhibitors of nitric oxide synthase, suggesting a link between reactive nitrogen species and arsenic-induced inflammation. Furthermore, there is a significant increase in prostacyclin (PGI2) in the serum of arsenic-treated mice. We conclude that changes in specific inflammatory mediators such as LTE4 and PGI2 are related to arsenic-induced atherosclerosis. In addition, amplified synthesis of reactive species such as peroxynitrite results in increased protein nitration in response to arsenic exposure. This finding is consistent with the pathology seen in human atherosclerotic plaques.",
Arsenic,1347196,"Heterogeneous redox conditions, arsenic mobility, and groundwater flow in a fractured-rock aquifer near a waste repository site in New Hampshire, USA Abstract: Anthropogenic sources of carbon from landfill or waste leachate can promote reductive dissolution of in situ arsenic (As) and enhance the mobility of As in groundwater. Groundwater from residential-supply wells in a fractured crystalline-rock aquifer adjacent to a Superfund site in Raymond, New Hampshire, USA, showed evidence of locally enhanced As mobilization in relatively reducing (mixed oxic-anoxic to anoxic) conditions as determined by redox classification and other lines of evidence. Redox classification was determined from geochemical indicators based on threshold concentrations of dissolved oxygen (DO), nitrate (NO (3) (-) ), iron (Fe2+), manganese (Mn2+), and sulfate (SO (4) (2-) ). Redox conditions were evaluated also based on methane (CH4), excess nitrogen gas (N-2) from denitrification, the oxidation state of dissolved As speciation (As(III) and As(V)), and several stable isotope ratios. Samples from the residential-supply wells primarily exhibit mixed redox conditions, as most have long open boreholes (typically 50-100 m) that receive water from multiple discrete fractures with contrasting groundwater chemistry and redox conditions. The methods employed in this study can be used at other sites to gauge redox conditions and the potential for As mobilization in complex fractured crystalline-rock aquifers where multiple lines of evidence are likely needed to understand As occurrence, mobility, and transport.",
Arsenic,2343471,"Geochemistry of acid mine drainage from a coal mining area and processes controlling metal attenuation in stream waters, southern Brazil Abstract: Acid drainage influence on the water and sediment quality was investigated in a coal mining area (southern Brazil). Mine drainage showed pH between 3.2 and 4.6 and elevated concentrations of sulfate, As and metals, of which, Fe, Mn and Zn exceeded the limits for the emission of effluents stated in the Brazilian legislation. Arsenic also exceeded the limit, but only slightly. Groundwater monitoring wells from active mines and tailings piles showed pH interval and chemical concentrations similar to those of mine drainage. However, the river and ground water samples of municipal public water supplies revealed a pH range from 7.2 to 7.5 and low chemical concentrations, although Cd concentration slightly exceeded the limit adopted by Brazilian legislation for groundwater. In general, surface waters showed large pH range (6 to 10.8), and changes caused by acid drainage in the chemical composition of these waters were not very significant. Locally, acid drainage seemed to have dissolved carbonate rocks present in the local stratigraphic sequence, attenuating the dispersion of metals and As. Stream sediments presented anomalies of these elements, which were strongly dependent on the proximity of tailings piles and abandoned mines. We found that precipitation processes in sediments and the dilution of dissolved phases were responsible for the attenuation of the concentrations of the metals and As in the acid drainage and river water mixing zone. In general, a larger influence of mining activities on the chemical composition of the surface waters and sediments was observed when enrichment factors in relation to regional background levels were used.",
Arsenic,1026446,"Association between total ingested arsenic and toenail arsenic concentrations Abstract: The association between arsenic exposure from drinking water and toenail arsenic concentrations appears to be non-linear at low exposure levels. To investigate whether this observation is a result exposure misclassification, a dietary exposure assessment was conducted in a cohort of 47 women concurrently enrolled in a prospective longitudinal biomonitoring study in Pabna, Bangladesh. Arsenic intake was evaluated using a duplicate diet study design which collected food and water samples for a total of 6 days. Total inorganic arsenic was measured in 24-hour composite food samples (N=282) using inductively coupled plasma-mass spectrometry coupled with a dynamic reaction cell (ICP-DRC-MS). Average annual tubewell arsenic concentrations and toenail arsenic concentrations were computed for each participant using biomonitoring data from the prospective study. Separate multivariate regression models evaluated the association between drinking water, total dietary intake, and total dietary dose with toenail arsenic, a biomarker of internal dose. In these models, dietary intakes were adjusted using the residual method to provide estimate that was independent of water arsenic concentrations. Median daily arsenic intake from food and drinking water was 48.3 microg/day and 4.2 microg/day. Taking into consideration participant's body weight, the median daily arsenic dose was 1.0 microg/kg-day from food and 0.1 microg/kg-day from drinking water although drinking water exposure was highly skewed and was the dominant exposure route for the upper 25th percentile of the distribution. The regression model that used total daily arsenic intake from food (beta=0.46; 95%CI: 0.18-0.73) and drinking water (95%CI: 0.26-0.38) explained the most variability in toenail arsenic concentrations (R(2)(a)=0.71). The effect estimates for food and drinking water are similar suggesting that both sources have a similar contribution to internal dose.",
Arsenic,1020697,"Role of metal-reducing bacteria in arsenic release from Bengal delta sediments Abstract: The contamination of ground waters, abstracted for drinking and irrigation, by sediment-derived arsenic threatens the health of tens of millions of people worldwide, most notably in Bangladesh and West Bengal. Despite the calamitous effects on human health arising from the extensive use of arsenic-enriched ground waters in these regions, the mechanisms of arsenic release from sediments remain poorly characterized and are topics of intense international debate. We use a microscosm-based approach to investigate these mechanisms: techniques of microbiology and molecular ecology are used in combination with aqueous and solid phase speciation analysis of arsenic. Here we show that anaerobic metal-reducing bacteria can play a key role in the mobilization of arsenic in sediments collected from a contaminated aquifer in West Bengal. We also show that, for the sediments in this study, arsenic release took place after Fe(III) reduction, rather than occurring simultaneously. Identification of the critical factors controlling the biogeochemical cycling of arsenic is one important contribution to fully informing the development of effective strategies to manage these and other similar arsenic-rich ground waters worldwide.",
Arsenic,627456,"Binding of dimethylarsinous acid to cys-13? of rat hemoglobin is responsible for the retention of arsenic in rat blood Abstract: The metabolism, disposition, and carcinogenicity of arsenic differ dramatically between humans and rats. To understand the molecular basis of these differences, we have characterized arsenic species in rats that were treated with inorganic arsenate (iAsV), monomethylarsonic acid (MMAV), or dimethylarsinic acid (DMAV) for up to 15 weeks. Arsenic significantly accumulated in the red blood cells (RBCs) of rats in the form of hemoglobin (Hb) complexed with dimethylarsinous acid (DMAIII), regardless of whether the rats were treated with iAsV, MMAV, or DMAV, suggesting rapid methylation of arsenic species followed by strong binding of DMAIII to rat Hb. The binding site for DMAIII was identified to be cysteine 13 in the alpha-chain of rat Hb with a stoichiometry of 1:1. Over 99% of the total arsenic (maximum 2.5-3.5 mM) in rat RBCs was bound to Hb for all rats examined (n = 138). In contrast, only 40-49% of the total arsenic (maximum approximately 10 muM) in rat plasma was bound to proteins. The ratios of the total arsenic in RBCs to that in plasma ranged from 88-423 for rats that were fed iAsV, 100-680 for rats that were fed MMAV, and 185-1393 for rats that were fed DMAV, when samples were obtained over the 15-week exposure duration. Previous studies have shown an increase in urothelial hyperplasia in rats fed DMAV. This is the first article reporting that treatment with iAsV in the drinking water also produces urothelial hyperplasia and at an even earlier time point than dietary DMAV. Dietary MMAV produced only a slight urothelial response. A correlation between the Hb-DMAIII complex and urothelial lesion severity in rats was observed. The lack of cysteine 13alpha in human Hb may be responsible for the shorter retention of arsenic in human blood. These differences in the disposition of arsenicals may contribute to the observed differences between humans and rats in susceptibility to arsenic carcinogenicity.",
Arsenic,1028909,"Cyclic arsenic-nitrogen cations Abstract: A series of different cyclo-diarsa-diazenium salts bearing several bulky groups such as supermesityl (Mes* = 2,4,6-tBu(3)C(6)H(2)) and m-terphenyl (2,6-Mes(2)-C(6)H(3), Mes = 2,4,6-Me(3)C(6)H(2)) and anions such as triflate (OTf = SO(3)CF(3) = trifluoromethylsulfonate) and tetrachloridogallate (GaCl(4)(-)) were synthesized and fully characterized. The novel 1-chloro-cyclo-1,3-diarsa-2,4-diazenium cation represents the first example of a binary cyclic As(III)/N four-membered heterocyclic cation, with a di- and tricoordinated As atom and a delocalized pi bond along the NAs((+))N unit. The addition of excess Me(3)SiN(3) yields the fully characterized cationic arsenic azide, 1-azido-cyclo-1,3-diarsa-2,4-diazenium-mu-azido-hexachlorido-digallate. The Cl(-)/N(3)(-) exchange is triggered by the action of the Lewis acid GaCl(3). Depending on the Me(3)SiN(3) stoichiometry, different mu-azido-hexachlorido-digallate salts with either 1-chloro- or 1-azido-cyclo-1,3-diarsa-2,4-diazenium cations or even a mixture of both are observed. Moreover, it was of special interest to study the distances between the cationic arsenic center and the anion in cyclo-diarsa-diazenium salts. A correlation between the color of the salt and the anion/cation distance, ranging between 2 and 8 A in cyclo-diarsa-diazenium salts of the type [R(2)N(2)As(2)Y](+)X(-) depending on the bulky group R (R = Mes*, Ter), the substituent Y (Y = Cl, N(3), OTf), and the anion X(-) (X = OTf, GaCl(4), Cl(3)Ga-N(3)-GaCl(3)), was established.",
Arsenic,2337287,"Frontal sinus drillout (modified Lothrop procedure): Long-term results in 204 patients Abstract: <strong>OBJECTIVES/HYPOTHESIS: </strong>To determine the long-term results of frontal sinus drillout (also known as modified Lothrop procedure) for the treatment of advanced frontal sinus disease.<br /><br /><strong>STUDY DESIGN: </strong>Retrospective review.<br /><br /><strong>METHODS: </strong>The records of patients who underwent frontal sinus drillout by a single surgeon at an academic medical center from June 1995 through November 2011 were reviewed. Patient demographics and perioperative clinical findings were analyzed for their impact on surgical outcome. Failure was defined as restenosis of the frontal drainage pathways, necessitating additional frontal sinus surgery.<br /><br /><strong>RESULTS: </strong>A total of 204 patients underwent frontal drillout surgery (143 bilateral procedures) over the 16-year period. Mean follow-up was 10.2 years (range 0.9-17 years). Symptomatic re-obstruction of the frontal sinus requiring revision surgery occurred in 61 (29.9%) patients. Drillouts performed for a diagnosis of mucocele or tumor had significantly higher failure rate (38.9%, odds ratio [OR]?=?2.9, P?=?0.022 and 58.3%, OR?=?5.3, P?=?0.020, respectively). The majority of surgical failures (61%) occurred within 2 years of surgery, but delayed failures were observed up to 12 years after drillout. Clinical outcome did not correlate with a history of smoking, asthma, nasal allergy, aspirin sensitivity, prior sinus surgery, nasal polyposis, or the presence of eosinophilic mucin.<br /><br /><strong>CONCLUSION: </strong>For the majority of patients who undergo frontal sinus drillout, patency of the frontal sinus outflow tract appears to be maintained for more than a decade; nevertheless, almost one-third of patients who undergo this procedure will ultimately require additional frontal sinus surgery.<br /><br /><strong>LEVEL OF EVIDENCE: </strong>4. Laryngoscope, 124:1066-1070, 2014.",
Arsenic,611940,"The molecular resonance fluorescence method for determination of arsenic in hair samples Abstract: A molecular resonance fluorescence quenching method for the determination of arsenic was proposed. The method is based on the quenching effect of As (V) on the molecular resonance fluorescence of Rhodamine B (RhB) in sulfuric acid medium and in the presence of molybdate and PVA. The influences of acidity, chemical and manifold variables on the sensitivity were studied. At the optimized conditions, the linear range for the determination of arsenic was 2.0 × 10?3–0.12 ?g ml?1 with the detection limit of 1.20 × 10?9 g ml?1. The relative standard deviations for the eleven replicate determinations of 0.006 ?g ml?1 and 0.060 ?g ml?1 of arsenic were 1.12% and 1.61%, respectively. The proposed method was applied successfully for the determination of trace arsenic in hair samples with the recoveries of 94.8–104.6%.",
Arsenic,32220,"Environmentally related disorders of the nervous system Abstract: Specific physical and chemical agents found in the workplace and in the general environment are responsible for characteristic pathologic processes within the nervous system. It has been shown that many neurotoxic agents produce a dose-related spectrum of impairment ranging from mild slowing of nerve conducting velocity or prolongation in reaction time to neuropathy and frank encephalopathy. Clinical manifestations are determined by the agent involved, by the dose of exposure, the vulnerability of the cellular target, the ability of the organism to metabolize and excrete the agent, and the ability to repair damage. An occupational history, including evaluation of evidence of specific agents and job history, is a critical component in the clinical management of individuals with suspect neurotoxic disease. Environmentally-induced disorders can be prevented by appropriate environmental controls. Prevention of neurotoxic disease is a complex process requiring continuous involvement of public health agencies and strong scientific research.",
Arsenic,734878,"Could removing arsenic from tobacco smoke significantly reduce smoker risks of lung cancer Abstract: If a specific biological mechanism could be determined by which a carcinogen increases lung cancer risk, how might this knowledge be used to improve risk assessment? To explore this issue, we assume (perhaps incorrectly) that arsenic in cigarette smoke increases lung cancer risk by hypermethylating the promoter region of gene p16INK4a, leading to a more rapid entry of altered (initiated) cells into a clonal expansion phase. The potential impact on lung cancer of removing arsenic is then quantified using a three-stage version of a multistage clonal expansion (MSCE) model. This refines the usual two-stage clonal expansion (TSCE) model of carcinogenesis by resolving its intermediate or &quot;initiated&quot; cell compartment into two subcompartments, representing experimentally observed &quot;patch&quot; and &quot;field&quot; cells. This refinement allows p16 methylation effects to be represented as speeding transitions of cells from the patch state to the clonally expanding field state. Given these assumptions, removing arsenic might greatly reduce the number of nonsmall cell lung cancer cells (NSCLCs) produced in smokers, by up to two-thirds, depending on the fraction (between 0 and 1) of the smoking-induced increase in the patch-to-field transition rate prevented if arsenic were removed. At present, this fraction is unknown (and could be as low as zero), but the possibility that it could be high (close to 1) cannot be ruled out without further data.",
Arsenic,88142,"Effects of co-administration of antioxidants and arsenicals on the rat urinary bladder epithelium Abstract: Oxidative stress has been increasingly recognized as a possible mechanism in the toxicity and carcinogenicity of various chemicals, including arsenic. Therefore, treatment with antioxidants may afford a protective effect against arsenic-induced cytotoxicity and carcinogenesis. Dimethylarsinic acid (DMAV) has been shown to be a bladder carcinogen in rats when administered at high doses (100 ppm) in the diet or in the drinking water. The main purpose of the present study was to evaluate the effects of co-administration of antioxidants with arsenicals on the rat urinary bladder epithelium in vitro and in vivo. In a previous experiment, treatment with 1000 ppm melatonin for two weeks did not inhibit cell proliferation induced in the rat urothelium by 100 ppm DMAV. In the current study, we examined the effects of five antioxidants that act via different mechanisms, on the in vitro cytotoxicity of various arsenicals, for the purpose of determining which antioxidants might have protective effects against arsenic-induced cytotoxicity. The antioxidants that inhibited cytotoxicity in vitro were then studied also in vivo. Melatonin showed slight inhibition of the cytotoxicity of arsenite, but had no effect on the other arsenicals. N-acetylcysteine (NAC) inhibited the cytotoxicity of monomethylarsonous acid (MMAIII), DMAV, dimethylarsinous acid (DMAIII), and trimethylarsine oxide (TMAO). Vitamin C inhibited cytotoxicity induced by arsenate, arsenite, MMAIII) and DMAIII. Tiron and Trolox had no effect on the cytotoxicity of any arsenical. The in vitro inhibitory effects of NAC and vitamin C on DMAV and on DMAIII, suggested that these antioxidants might afford preventive effects on DMAV-induced bladder cytotoxicity and carcinogenesis in rats. To test this hypothesis, a 10-week rat bioassay was conducted. Melatonin was also included to clarify the results of the previous two-week experiment. The sodium salt of vitamin C (Na-Asc), but not melatonin or NAC, inhibited the proliferative effects of DMAV on the bladder epithelium in rats. These results suggest that oxidative stress is at least in part involved in DMAV-induced rat bladder toxicity and proliferation, and therefore, vitamin C may afford inhibitory effects in DMAV-induced bladder carcinogenesis in rats. Microarray analysis of DMAV-responsive genes revealed that DMAV did not have a consistent modifying effect on gene expression in the rat bladder epithelium, suggesting that proteins and/or lipids may be the targets of damage by DMAV-induced oxidative stress.",
Arsenic,628391,"Survey of arsenic and other heavy metals in food composites and drinking water and estimation of dietary intake by the villagers from an arsenic-affected area of West Bengal, India Abstract: An investigation of arsenic, copper, nickel, manganese, zinc and selenium concentration in foodstuffs and drinking water, collected from 34 families and estimation of the average daily dietary intake were carried out in the arsenic-affected areas of the Jalangi and Domkal blocks, Murshidabad district, West Bengal where arsenic-contaminated groundwater (mean: 0.11 mg/l, n=34) is the main source for drinking. The shallow large diameter tubewells, installed for agricultural irrigation contain an appreciable amount of arsenic (mean: 0.094 mg/l, n=10). So some arsenic can be expected in the food chain and food cultivated in this area. Most of the individual food composites contain a considerable amount of arsenic. The mean arsenic levels in food categories are vegetables (20.9 and 21.2 microg/kg), cereals and bakery goods (130 and 179 microg/kg) and spices (133 and 202 microg/kg) for the Jalangi and Domkal blocks, respectively. For all other heavy metals, the observed mean concentration values are mostly in good agreement with the reported values around the world (except higher zinc in cereals). The provisional tolerable daily intake value of inorganic arsenic microg/kg body wt./day) is: for adult males (11.8 and 9.4); adult females (13.9 and 11); and children (15.3 and 12) in the Jalangi and Domkal blocks, respectively (according to FAO/WHO report, the value is 2.1 microg/kg body wt./day). According to WHO, intake of 1.0 mg of inorganic arsenic per day may give rise to skin lesions within a few years. The average daily dietary intake of copper, nickel and manganese is high, whereas for zinc, the value is low (for adult males: 8.34 and 10.2 mg/day; adult females: 8.26 and 10.3 mg/day; and children: 4.59 and 5.66 mg/day) in the Jalangi and Domkal blocks, respectively, compared to the recommended dietary allowance of zinc for adult males, adult females and children (15, 12 and 10 mg/day, respectively). The average daily dietary intake of selenium microg/kg body wt./day) is on the lower side for the children (1.07 and 1.22), comparable for the adult males (0.81 and 0.95) and slightly on the higher side for the adult females (1.08 and 1.26), compared to the recommended value (1.7 and 0.9 microg/kg body wt./day for infants and adults, respectively).",
Arsenic,2279035,"Metabolomic study in plasma, liver and kidney of mice exposed to inorganic arsenic based on mass spectrometry Abstract: The mechanism of arsenic toxicity still remains unclear, although enzymatic inhibition, impaired antioxidants metabolism and oxidative stress may play a role. The toxicological effects of trivalent inorganic arsenic on laboratory mouse Mus musculus after oral administration (3 mg/kg body weight/day) were investigated along 12 days, using a metabolomic approach based on direct infusion mass spectrometry to polar and lipophilic extracts from different organs and fluids (liver, kidney, and plasma). Positive and negative acquisition modes (ESI(+)/ESI(-)) were used throughout the experiments. The most significant endogenous metabolites affected by exposure were traced by partial least square-discriminant analysis and confirmed by tandem mass spectrometry (MS/MS) and gas chromatography coupled to MS. In this work, the toxic effect of arsenic has been related with important metabolic pathways, such as energy metabolism (e.g., glycolysis, Krebs cycle), amino acids metabolism, choline metabolism, methionine cycle, and degradation of membrane phospholipids (cell apoptosis). In addition, this work illustrates the high reliability of mass spectrometry based on a metabolomic approach to study the biochemical effects induced by metal exposure.",
Arsenic,1032954,"Alterations of mitogenic responses of mononuclear cells by arsenic in arsenical skin cancers Abstract: We have studied the endemic occurrence of chronic arsenism in a limited area on the southwest coast of Taiwan. The effects of arsenic on the mitogenic responses of mononuclear cells (MNC) derived from patients with arsenical skin cancers in that area were evaluated. The subjects enrolled in this study included patients with 1) Bowen's disease, 2) arsenical skin cancers (basal cell carcinoma and squamous cell carcinoma), 3) non-arsenical skin cancers (basal cell carcinoma and squamous cell carcinoma), 4) nasopharyngeal cancer and 5) healthy controls from endemic and non-endemic areas. Phytohemagglutinin (PHA) stimulated [3H]thymidine incorporation in MNC in all groups except the arsenical skin cancer group. However, when a low concentration of As2O3 (2.5 x 10(-7) M) was added to PHA-stimulated MNC, a tremendous amplification of the uptake of [3H]thymidine was noticed in patients with arsenical skin cancer. In this study, this phenomenon did not occur in cancers not related to arsenic. This result shows that arsenical carcinomas are hyperreactive to its specific etiology--arsenic. Arsenic seems to play a role as a co-stimulant of PHA similar to interleukin-1.",
Arsenic,575010,"Exposure to monomethylarsonous acid (MMAIII) leads to altered selenoprotein synthesis in a primary human lung cell model Abstract: Monomethylarsonous acid (MMAIII), a trivalent metabolite of arsenic, is highly cytotoxic and recent cell culture studies suggest that it might act as a carcinogen. The general consensus of studies indicates that the cytotoxicity of MMAIII is a result of increased levels of reactive oxygen species (ROS). A longstanding relationship between arsenic and selenium metabolism has led to the use of selenium as a supplement in arsenic exposed populations, however the impact of organic arsenicals (methylated metabolites) on selenium metabolism is still poorly understood. In this study we determined the impact of exposure to MMAIII on the regulation of expression of TrxR1 and its activity using a primary lung fibroblast line, WI-38. The promoter region of the gene encoding the selenoprotein thioredoxin reductase 1 (TrxR1) contains an antioxidant responsive element (ARE) that has been shown to be activated in the presence of electrophilic compounds. Results from radiolabeled selenoproteins indicate that exposure to low concentrations of MMAIII resulted in increased synthesis of TrxR1 in WI-38 cells, and lower incorporation of selenium into other selenoproteins. MMAIII treatment led to increased mRNA encoding TrxR1 in WI-38 cells, while lower levels of mRNA coding for cellular glutathione peroxidase (cGpx) were detected in exposed cells. Luciferase activity of TrxR1 promoter fusions increased with addition of MMAIII, as did expression of a rat quinone reductase (QR) promoter fusion construct. However, MMAIII induction of the TRX1 promoter fusion was abrogated when the ARE was mutated, suggesting that this regulation is mediated via the ARE. These results indicate that MMAIII alters the expression of selenoproteins based on a selective induction of TrxR1, and this response to exposure to organic arsenicals that requires the ARE element.",
Arsenic,1579348,"Occurrence of trivalent monomethyl arsenic and other urinary arsenic species in a highly exposed juvenile population in Bangladesh Abstract: Following reports of high cytotoxicity and mutagenicity of monomethyl arsonous acid (MMA(III)) and early reports of urinary MMA(III) in arsenic-exposed individuals, MMA(III) has often been included in population studies. Use of urinary MMA(III) as an indicator of exposure and/or health risk is challenged by inconsistent results from field studies and stability studies, which indicate potential artifacts. We measured urinary arsenic species in children chronically exposed to arsenic in drinking water, using collection, storage, and analysis methods shown to conserve MMA(III). MMA(III) was easily oxidized in sample storage and processing, but recoveries of 80% or better in spiked urine samples were achieved. Attempts to preserve the distribution of MMA between trivalent and pentavalent forms using complexing agents were unsuccessful and MMA(III) spiked into treated urine samples actually showed lower stability than in untreated samples. In 643 urine samples from a highly exposed population from the Matlab district in Bangladesh stored for 3-6 months at ?-70?°C, MMA(III) was detected in 41 samples, with an estimated median value of 0.3??g/l, and levels of MMA(III) above 1??g/l in only two samples. The low urinary concentrations in highly exposed individuals and known difficulties in preserving sample oxidation state indicate that urinary MMA(III) is not suitable for use as an epidemiological biomarker.Journal of Exposure Science and Environmental Epidemiology advance online publication, 3 April 2013; doi:10.1038/jes.2013.14.",
Arsenic,668057,"Trichloroethylene, tetrachloroethylene, nitrates, and other chemicals in well water in the Fresno-Clovis Metropolitan Area Abstract: In this study, the author examined the spatial and temporal distribution of tetrachloroethylene, trichloroethylene, nitrate, and several other organic and inorganic chemicals in large community wells in the Fresno-Clovis Metropolitan Area and estimated the lifetime cancer risk associated with exposure to tetrachloroethylene and trichloroethylene. By 1992-1993, investigators found the industrial solvent tetrachloroethylene in 34 wells and found trichloroethylene in 16 wells. All wells had detectable levels of nitrate. In addition, investigators found radon, arsenic, cadmium, iron, manganese, trihalomethanes, and several other volatile organic chemicals in the wells, but only radon and arsenic posed a significant health risk. In 1995, 16 wells were closed because chemicals were found in them. Twenty-six of 248 (10.5%) active wells and 24 of 43 (55.8%) closed wells contained multiple contaminants, excluding nitrate. Between 1988 and 1993, concentrations of trichloroethylene, tetrachloroethylene, and nitrates increased in selected wells. Daily, monthly, and bimonthly variations in the concentrations of tetrachloroethylene, trichloroethylene, and nitrate were often considerable. Granulated activated carbon filtration reduced trichloroethylene levels in well water by 91%–95%, and the author examined its usefulness as a remedial measure. Estimated lifetime cancer risks for tetrachloroethylene and trichloroethylene were 1 excess cancer death per 9.5 million people and 1 excess death per 250 million, respectively. The author also included recommendations for the conduct of further epidemiological and environmental studies.",
Arsenic,744831,"Arsenic methyltransferase Cyt19 expression and activity in rat tissues Abstract: Inorganic arsenicals such as arsenite (iAsIII) and arsenate (iAsV) are well-known worldwide environmental contaminants and human carcinogen. Arsenic is known to be metabolized by repetitive reduction and methylation, and excreted mainly in urine as methylated arsenicals such as monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV). Although it has been known that the arsenic methylation is catalyzed by arsenic methyltransferase, Cyt 19, very little is known about characteristics of the enzyme. In the present study we report gene expression and enzyme activity of Cyt19 in rat tissues. We investigated mRNA and protein levels of Cyt19 in rat tissues, such as heart, brain, spleen, lung, liver, skeletal muscle, kidney and testis, by Northern and Western analysis, respectively. The rat tissues cytosol was incubated at 37 ?C for 3 h with 10 ?M iAsIII, 5 mM GSH and 1 mM Sadenosyl- L-methionine in 75 mM phosphate buffer (pH 7.0). The reaction was stopped by boiling the reaction mixture for 5 min, and then treated with H2O2 to oxidize all arsenicals to pentavalency. The metabolites, MMAV and DMAV, were analyzed on a reversed phase column by high-performance liquid chromatographyinductively coupled argon plasma mass spectrometry (HPLC-ICP MS). Both mRNA and protein levels were highest in the liver. The intermediate expression of Cyt19 mRNA was observed in heart and testis. However, arsenic methylating activity was detected only in the liver cytosol using the current HPLC-ICP MS method.",
Arsenic,1019401,"Species differences in arsenic-mediated renal copper accumulation: a comparison between rats, mice and guinea pigs Abstract: 1. Administration of arsenite leads to an accumulation of copper in the rat kidney. Owing to the high retention of arsenic in the erythrocytes, however, the rat is considered to possess special toxicokinetics of arsenic and is therefore considered less comparable with other species in this respect. 2. Therefore, we compared the effect of dietary arsenite in mice and guinea pigs with that in rats. Each species was divided into four groups of animals according to the diets fed which contained increasing concentrations of sodium arsenite (NaAsO2; 0, 10, 30 and 60 mg As/kg of diet). Animals were killed after 1, 2 and 3 weeks. Tissues were sampled and analyzed for arsenic and other trace metals (Cu, Fe, Zn and Mn). 3. Compared to controls with copper levels of about 10 microg Cu/g wet wt. in the renal cortex, dietary administration of arsenite up to 60 mg As/kg of diet for 3 weeks to rats increased cortical levels to 65 microg Cu/g wet wt. An increase of renal copper levels similar to that in rats, was only observed in guinea pigs but not in mice. Renal copper accumulation in guinea pigs was time- and concentration-dependent as in rats. Feeding a diet with 60 mg As/kg for 3 weeks increased cortical copper levels from about 6 - 40 microg Cu/g wet wt. Renal copper levels in mice as well as other trace metal levels in guinea pigs and mice were not essentially altered by dietary arsenite. 4. The study shows that the renal copper-arsenic interaction is not restricted to the rat. Since in rats and guinea pigs, but not in mice, arsenic accumulated in the kidney rather similarly, a common mechanism is suggestive. As it was previously shown in rats that only inorganic arsenic is involved in this interaction, a rapid conversion of the inorganic form into methylated metabolites as in mice may diminish the extent of the renal copper accumulation whereas the lack of, or a less efficient, methylation as in guinea pigs or rats increases it.",
Arsenic,1346046,"Stress-induced glucose uptake in bovine chromaffin cells: a comparison of the effect of arsenite and anisomycin Abstract: The effect of the toxic chemical Na-arsenite and the protein synthesis inhibitor anisomycin on glucose transport in primary cultures of bovine chromaffin cells was compared using the effect of insulin-like growth factor I (IGF-I) as a reference. The enhanced uptake of glucose obtained in response to arsenite and anisomycin reached maximum after 60 min, with the response to anisomycin being delayed in onset relative to that of arsenite. At maximal doses the arsenite effect was consistently higher than that of anisomycin and comparable to the approximately 2-fold effect produced by IGF-I. The selective inhibitor of stress-activated protein kinase 2 (SAPK2), SB 203580, inhibited completely anisomycin-induced glucose uptake but only partly suppressed uptake stimulated by arsenite. Both substances, in concentrations producing maximal effects on glucose transport, led to a strong phosphorylation of SAPK2. In contrast to the effect on glucose transport, the arsenite-induced phosphorylation of SAPK2 was relatively slow compared to the anisomycin-induced activation. The results indicate that glucose uptake induced by the two types of cellular stress are mediated by at least two different signaling pathways, which also differ from that activated by IGF-I.",
Arsenic,1508664,"Quantification of arsenic, lead, mercury and cadmium in newborn dried blood spots Abstract: Exposures to heavy metals during fetal and perinatal development are of particular concern. Yet, the health impacts of exposures to toxic metals during these early stages of human development are not well understood due to the paucity of in vivo human data. Dried blood spots (DBS), collected by public health departments to screen for inherited metabolic errors and other disorders, are routinely archived and can be used for exposure assessment. Here we report an improved method for quantifying arsenic, lead, mercury and cadmium in newborn DBS to facilitate epidemiologic research on the health effects of early exposures to toxic metals.",
Arsenic,1018715,"Determination of total arsenic in serum and packed cells of patients with renal insufficiency Abstract: In order to investigate the arsenic level in serum and packed cells of patients with renal insufficiency, total arsenic (As) concentrations were determined with hydride generation atomic absorption spectrometry (HGAAS) in serum (S) and packed cells (PC) of 31 non-dialyzed patients. The accuracy of the method was tested by the analysis of arsenic in 3 certified reference materials. Patients showed a three-fold increase of arsenic concentrations in serum and a two-fold increase of arsenic in packed cells compared with controls. Patients (n=10) with higher serum creatinine (>2.0 mg/dL), urea (>0.70 g/L) and urinary protein (mean+/-SD: 1.12+/-0.82 g/L) showed higher arsenic concentrations (5.8+/-3.3 microg/L in serum and 18.0+/-16.7 microg/kg in packed cells) compared with those with lower creatinine (<1.6 mg/dL), urea (<0.6 g/L) and urinary protein (mean+/-SD: 0.27+/-0.82 g/L) (n=16, serum arsenic 1.2+/-1.2 microg/L, packed cells arsenic 2.6+/-1.9 microg/kg). The significant differences (both p < 0.001) in S and PC-arsenic levels of patients in group I and II implies a relationship between the arsenic level and the degree of chronic renal insufficiency.",
Arsenic,2337139,"In vitro toxicological characterisation of three arsenic-containing hydrocarbons Abstract: Arsenic-containing hydrocarbons are one group of fat-soluble organic arsenic compounds (arsenolipids) found in marine fish and other seafood. A risk assessment of arsenolipids is urgently needed, but has not been possible because of the total lack of toxicological data. In this study the cellular toxicity of three arsenic-containing hydrocarbons was investigated in cultured human bladder (UROtsa) and liver (HepG2) cells. Cytotoxicity of the arsenic-containing hydrocarbons was comparable to that of arsenite, which was applied as the toxic reference arsenical. A large cellular accumulation of arsenic, as measured by ICP-MS/MS, was observed after incubation of both cell lines with the arsenolipids. Moreover, the toxic mode of action shown by the three arsenic-containing hydrocarbons seemed to differ from that observed for arsenite. Evidence suggests that the high cytotoxic potential of the lipophilic arsenicals results from a decrease in the cellular energy level. This first in vitro based risk assessment cannot exclude a risk to human health related to the presence of arsenolipids in seafood, and indicates the urgent need for further toxicity studies in experimental animals to fully assess this possible risk.",
Arsenic,710795,"Adverse health effects due to arsenic exposure: modification by dietary supplementation of jaggery in mice Abstract: Populations of villages of eastern India and Bangladesh and many other parts of the world are exposed to arsenic mainly through drinking water. Due to non-availability of safe drinking water they are compelled to depend on arsenic-contaminated water. Generally, poverty level is high in those areas and situation is compounded by the lack of proper nutrition. The hypothesis that the deleterious health effects of arsenic can be prevented by modification of dietary factors with the availability of an affordable and indigenous functional food jaggery (sugarcane juice) has been tested in the present study. Jaggery contains polyphenols, vitamin C, carotene and other biologically active components. Arsenic as sodium-m-arsenite at low (0.05 ppm) and high (5 ppm) doses was orally administered to Swiss male albino mice, alone and in combination with jaggery feeding (250 mg/mice), consecutively for 180 days. The serum levels of total antioxidant, glutathione peroxidase and glutathione reductase were substantially reduced in arsenic-exposed groups, while supplementation of jaggery enhanced their levels in combined treatment groups. The serum levels of interleukin-1beta, interleukin-6 and TNF-alpha were significantly increased in arsenic-exposed groups, while in the arsenic-exposed and jaggery supplemented groups their levels were normal. The comet assay in bone marrow cells showed the genotoxic effects of arsenic, whereas combination with jaggery feeding lessened the DNA damage. Histopathologically, the lung of arsenic-exposed mice showed the necrosis and degenerative changes in bronchiolar epithelium with emphysema and thickening of alveolar septa which was effectively antagonized by jaggery feeding. These results demonstrate that jaggery, a natural functional food, effectively antagonizes many of the adverse effects of arsenic.",
Arsenic,1022520,"Oxidative stress contributes to arsenic-induced telomere attrition, chromosome instability, and apoptosis Abstract: The environmental contaminant arsenic causes cancer, developmental retardation, and other degenerative diseases and, thus, is a serious health concern worldwide. Paradoxically, arsenic also may serve as an anti-tumor therapy, although the mechanisms of its antineoplastic effects remain unclear. Arsenic exerts its toxicity in part by generating reactive oxygen species. We show that arsenic-induced oxidative stress promotes telomere attrition, chromosome end-to-end fusions, and apoptotic cell death. An antioxidant, N-acetylcysteine, effectively prevents arsenic-induced oxidative stress, telomere erosion, chromosome instability, and apoptosis, suggesting that increasing the intracellular antioxidant level may have preventive or therapeutic effects in arsenic-induced chromosome instability and genotoxicity. Embryos with shortened telomeres from late generation telomerase-deficient mice exhibit increased sensitivity to arsenic-induced oxidative damage, suggesting that telomere attrition mediates arsenic-induced apoptosis. Unexpectedly, arsenite did not cause chromosome end-to-end fusions in telomerase RNA knockout mouse embryos despite progressively damaged telomeres and disrupting embryo viability. Together, these findings may explain why arsenic can initiate oxidative stress and telomere erosion, leading to apoptosis and anti-tumor therapy on the one hand and chromosome instability and carcinogenesis on the other.",
Arsenic,2343517,"Porcine small intestine submucosal grafts for post-tumor resection orbital reconstruction Abstract: Objectives/Hypothesis Removal of the medial orbital wall for sinonasal tumor involvement is required to obtain complete oncologic resection. However, orbital fat herniation can produce significant morbidity, including enophthalmos and diplopia. The purpose of the current study was to evaluate outcomes following use of porcine small intestine submucosa (SIS) grafts for orbital reconstruction following extirpation of sinonasal malignancies. Study Design Case series in a tertiary hospital setting. Methods Review of prospectively collected data regarding orbital reconstruction using SIS was performed. Demographics, tumor histology, size of orbital defect, adjuvant treatment, clinical status, and complications were recorded.",
Arsenic,628271,"Experimental exposure of arsenic in cultured rat intestinal epithelial cells and cell line: Toxicological consequences Abstract: Arsenic is a naturally occurring metalloid and the drinking water contamination by inorganic arsenic remains a major public health problem. The trivalent arsenic (arsenite) is more toxic than the pentavalent form (arsenate), and is known to cause gastrointestinal toxicity. Specific immortal cell lines are considered to be suitable for toxicity screening and testing of chemicals as they are easy to handle and possess most of the biochemical pathways present in the corresponding cells present in vivo. The present study was designed to evaluate and compare the in vitro toxicity of arsenite on rat intestinal epithelial cell line (IEC-6) and primary cultures of rat intestinal epithelial cells (IEC). To evaluate in vitro toxicity, cultures of IEC and IEC-6 cells were assessed for viability, morphometric analysis, membrane transport enzymes and structural constituents for membrane damage, dehydrogenase activity test for respiratory and energy producing processes and esterase activity test for intra and extra cellular degradation, following the post exposures to arsenite (0-20 ppm). Significantly similar concentration-dependent changes in these toxicity-screening parameters in IEC and IEC-6 were observed. Highest tested concentration of arsenite (20 ppm) was found to be detrimental in both IEC and IEC-6. Furthermore, to evaluate arsenite toxicity in epithelial cells of rat intestine, intestinal loops were filled with arsenite solutions and incubated for 30 min in situ. In situ studies also showed a significant arsenite concentration-dependent decline in epithelial cell membrane transport enzyme activities and total hexose and sialic acid contents. Concomitant release of membrane enzymes, hexose and sialic acid in the intestinal luminal fluid following higher arsenite exposures further indicated partial membrane damage. Similar morphological changes in IEC and IEC-6 were also evident. These findings also suggest that IEC-6 cell lines are suitable for initial screening of gastrointestinal cellular toxicity caused by arsenite.",
Arsenic,532483,"Children's intellectual function in relation to arsenic exposure Abstract: Background: Very little evidence exists concerning the possible impairment of children's intellectual function in relation to arsenic exposure in utero and during childhood. Methods: We conducted a cross-sectional study among 351 children age 5 to 15 years who were selected from a source population of 7683 people in West Bengal, India, in 2001-2003. Intellectual function was assessed with 6 subtests from the Wechsler Intelligence Scale for Children as well as with the Total Sentence Recall test, the Colored Progressive Matrices test, and a pegboard test. Arsenic in urine and lifetime water sources (including during the pregnancy period) were assessed using measurements of samples from 409 wells. The test scores were analyzed with linear regression analyses based on the method of generalized estimating equations incorporating relevant covariates. Results: Stratifying urinary arsenic concentrations into tertiles, we found associations between arsenic and reductions in the adjusted scores of the vocabulary test (0, -0.14, -0.28; P for trend = 0.02), the object assembly test (0, -0.16, -0.24- P for trend = 0.03), and the picture completion test (0, - 0.15, -0.26; P for trend = 0.02). These findings correspond to relative declines of 12% (95% confidence interval =0.4% to 24%) in the vocabulary test, 21% (-0.8% to 42%) in the object assembly test, and of 13% (0.3% to 24%) in the picture completion test in the upper urinary arsenic tertile. However, we did not find evidence of an association between test results and arsenic water concentrations during pregnancy or childhood. Conclusions: Current arsenic concentrations in urine, which reflect all sources of recent exposure, including water and food, were associated with small decrements in intellectual testing in school-aged children in West Bengal. We did not see associations between long-term water arsenic concentrations and intellectual function.",
Arsenic,1245797,"Expression of the 25-kDa heat-shock protein (HSP27) correlates with resistance to the toxicity of cadmium chloride, mercuric chloride, cis-platinum(II)-diammine dichloride, or sodium arsenite in mouse embryonic stem cells transfected with sense or antisense HSP27 cDNA Abstract: Embryonic stem (ES) cells were transfected with the protein-coding region of rat HSP27 cDNA placed in sense or antisense orientation in vector pcDNA3 under the control of the constitutive cytomegalovirus (CMV) promoter. Compared with nontransfected ES cells, five sense HSP27 cDNA-transfected ES cell clones displayed up to fourfold increases in expression of HSP27 mRNA and up to sixfold increases in expression of HSP27 protein, whereas four antisense HSP27 cDNA-transfected ES cell lines exhibited synthesis of antisense HSP27 RNA and a 50-85% decrease in HSP27 protein expression. Compared to the parental ES cell lines or ES cells transfected with the vector lacking any HSP27 sequence, all ES cell lines overexpressing HSP27 were resistant to killing by cadmium chloride (CdCl2), mercuric chloride (HgCl2), cis-platinum(II)-diammine dichloride (cDDP), sodium arsenite (NaAsO2), and heat while ES cell lines expressing reduced HSP27 were more sensitive to metal toxicity and heat. The relative toxicities of the tested metals to ES cells were cDDP &gt; NaAsO2 &gt; HgCl2 &gt; CdCl2. Protection of ES cells against metal or heat toxicity was positively correlated with the level of HSP27. These data confirm in ES cells previous reports of the ability of HSP27 to protect other cell types against heat and demonstrate that HSP27 protects mammalian cells against the toxic effects of diverse metals.",
Arsenic,1579246,"Charles Darwin's mitochondria Abstract: Charles Darwin's long-term illness has been the subject of much speculation. His numerous symptoms have led to conclusions that his illness was essentially psychogenic in nature. These diagnoses have never been fully convincing, however, particularly in regard to the proposed underlying psychological background causes of the illness. Similarly, two proposed somatic causes of illness, Chagas disease and arsenic poisoning, lack credibility and appear inconsistent with the lifetime history of the illness. Other physical explanations are simply too incomplete to explain the range of symptoms. Here, a very different sort of explanation will be offered. We now know that mitochondrial mutations producing impaired mitochondrial function may result in a wide range of differing symptoms, including symptoms thought to be primarily psychological. Examination of Darwin's maternal family history supports the contention that his illness was mitochondrial in nature; his mother and one maternal uncle had strange illnesses and the youngest maternal sibling died of an infirmity with symptoms characteristic of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS syndrome), a condition rooted in mitochondrial dysfunction. Darwin's own symptoms are described here and are in accord with the hypothesis that he had the mtDNA mutation commonly associated with the MELAS syndrome.",
Arsenic,2149156,"A short-term study to evaluate the uptake and accumulation of arsenic in Asian willow (Salix sp.) from arsenic-contaminated water Abstract: Five Asian willow species (Salix jiangsuensis J172, Salix matsudana, Salix integra Yizhibi, Salix integra Weishanhu, and Salix mongolica) were evaluated for their potential for phytofiltration of arsenic (As) from synthetically contaminated waters. Arsenic accumulation, tolerance, uptake influx, and phytofiltration ability of the five willow species were examined under hydroponic conditions in a glasshouse. Short-term exposure (2 weeks) to solutions containing 80 ?mol L(-1) arsenate (As(V)), resulted in significant accumulation of As in all willow species. Arsenic concentration in plant roots ranged from 322 mg kg(-1) dry weight (DW) for S. matsudana to 604 mg kg(-1) (DW) for S. integra Yizhibi. S. integra Yizhibi decreased As(V) concentration in water from 3.87 to 1.89 ?mol L(-1) (290 to 142 ?g L(-1)) over 168 h, which is 50 % of the total As(V) in the solution. The results suggested that even though Asian willow was not a traditional aquatic species, it still had significant potential for phytofiltration of As from contaminated waters. Of the five willow species studied, S. integra Yizhibi had the greatest capacity to remove As from As-contaminated waters. Thus, Asian willow has significant potential for the phytofiltration of As and may also be suitable for practical phytoremediation of As in highly water-logged areas.",
Arsenic,1579265,"Toxic effects of perinatal arsenic exposure on the brain of developing rats and the beneficial role of natural antioxidants Abstract: The aim of this study was to determine what changes in biochemical parameters and in the antioxidant capacity occur in the brain of arsenic-exposed rats (50mg As/L in drinking water) and investigate the protective effect of antioxidants as Zn, vitamin C and vitamin E during pregnancy and lactation. After arsenic-exposure, alkaline phosphatase (ALP) activity was enhanced in arsenic group, returning to normal levels in the arsenic+antioxidants one. A significant increase of acetylcholinesterase (AChE) activity was noted in both arsenic groups. Metalloide exposure caused a significant increase in lipid peroxidation (TBARS), whereas antioxidant administration reversed it. Catalase (CAT) activity in arsenic groups was increased, but no changes were found in the other groups. No significant effect of arsenic in superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and reduced glutathione concentration (GSH) was noted. This study provides evidence of the deleterious effect of arsenic exposure during gestation and lactation and the beneficial role of antioxidants.",
Arsenic,1020043,"Study of the content of heavy metals related to environmental load in urban areas in Slovakia Abstract: <strong>UNLABELLED: </strong>It is natural for the man to take care of his environment so the negative influences of intensification of industrial and agricultural production and the entire process of pollution are kept at minimum or eliminated as early as possible. However, they must first be identified.<br /><br /><strong>BACKGROUND: </strong>companion animals, for example dogs, are a very good indicator of the pollution load on the environment. They inhabit the same space as humans and are exposed to the action of the same pollutants. The most important role in contamination of the environment with heavy metals is played by emissions of different origin. For that reason it is appropriate and advantageous to evaluate the load on the man by parallel evaluation of the heavy metal load on dogs, particularly in large town agglomerations.<br /><br /><strong>MAIN PURPOSE: </strong>the aim of the study was to compare and evaluate the content of three heavy metals, cadmium, arsenic and lead, in the hair of dogs from two largest town agglomerations of Slovakia, Bratislava and Kosice. In addition to that, an effort was made to compare the environmental load in Bratislava and Kosice by using the dog as a bioindicator of environmental pollution with heavy metals and to quantify the content of heavy metals in dog' hair.<br /><br /><strong>METHODS: </strong>The generally low level of heavy metals in biological material makes it impossible to use common analytical methods. In our study the samples of dog hair were analysed using the method of atomic absorption spectrometry. The measurements were carried out on a Perkin-Elmer spectrometer, model 5000, using the following wavelengths: 228.8 nm for Cd, 193.7 nm for As and 283.3 nm for Pb. The results of analyses are presented as means. The concentrations of Cd, As and Pb are expressed in microg/kg dog hair. Statistical evaluation of results was carried out by means of Student's t-test.<br /><br /><strong>RESULTS: </strong>The mean values of heavy metals in the set of dogs from Bratislava reached the following levels: 38.09 microg/kg for Cd, 111.07 microg/kg for As, and 729.59 microg/kg for Pb. The set of dogs from Kosice allowed us to detect the following mean values: 22.21 microg/kg for Cd, 79.87 microg/kg for As, and 542.49 microg/kg for Pb. The mean values for the entire Slovak territory reached 27.39 microg/kg for Cd, 90.06 microg/kg for As, and 601.96 microg/kg for Pb. The comparison of the first two experimental sets of data with the Slovak mean values showed highly significant differences in arithmetic means (p &lt; 0.01) for Cd and significant (p &lt; 0.05) for As with the Bratislava set reaching higher values. No statistically significant differences were observed with regard to Pb.<br /><br /><strong>CONCLUSION: </strong>The study confirms the need for further research in this area with the dog as a bioindicator involving also other environmental loads not only that resulting from heavy metals. It indicates the importance of risk assessment in relation to environmental pollution. As the studies on animals are applicable also to the human population it appears very appropriate to use also this indirect way to point out to the negative impact of the polluted environment. Lead, cadmium and arsenic are the heavy metals that raise particular concern because of their wide-spectrum negative influences on live organisms. (Tab. 4, Fig. 5, Ref 28.)",
Arsenic,1579253,"Nona-copper(II)-containing 18-tungsto-8-arsenate(III) exhibits antitumor activity Abstract: The nona-CuII-containing tungstoarsenate(III) [H4{CuII9AsIII6O15(H2O)6}(?-AsIIIW9O33)2]8- (1a) has been synthesized and characterized. Polyanion comprises a unique, cylindrical {CuII9AsIII6O15(H2O)6}6+ cluster, which forms a large central cavity and is capped on either end by an [?-AsIIIW9O33]9- capping group. It exhibits remarkable activity against K562 leukaemia cells, as well as induces HepG2 cell apoptosis and autophagy.",
Arsenic,1017777,"Toxic effects of various pollutants in 11B7501 lymphoma B cell line from harbour seal (Phoca vitulina) Abstract: Although, heavy metals and polycyclic aromatic hydrocarbons (PAHs) have been reported at high levels in marine mammals, little is known about the toxic effects of some of these contaminants. In this study, we assessed the immunotoxic and genotoxic effects of seven heavy metals (arsenic, vanadium, selenium, iron, zinc, silver and chromium) and one PAH (benzo[a]pyrene or B[a]P) on a lymphoma B cell line from harbour seal (Phoca vitulina). A significant reduction in lymphocyte proliferation was registered following an exposure to 0.05 microM of B[a]P, 5 microM of arsenic or selenium, 50 microM of vanadium, 100 microM of silver and 200 microM of iron. On the contrary, zinc increased the lymphoproliferative response at 200 microM. Decreased phagocytosis was observed at 20 microM of arsenic, 50 microM of B[a]P or selenium, 200 microM of zinc and 500 microM of vanadium. Micronuclei induction occurred with 0.2 microM of B[a]P, 100 microM of vanadium and with 200muM of arsenic or selenium. Exposure to 50muM of arsenic decreased G(2)/M phase of the cell cycle. Chromium did not induce any effects at the concentrations tested. Concentrations of heavy metals (except silver and vanadium) and B[a]P inducing an toxic effect are within the environmental ranges reported in the blood tissue of pinnipeds. The reduction of some functional activities of the harbour seal immune system may cause a significant weakness capable of altering host resistance to disease in free-ranging pinnipeds.",
Arsenic,1579390,Predicting natural arsenic contamination of bedrock groundwater for a local region in Korea and its application Abstract: ,
Arsenic,734866,"Decreased urinary beta-defensin-1 expression as a biomarker of response to arsenic Abstract: Ingestion of arsenic (As) through contaminated drinking water results in increased risks of skin, lung, kidney, and bladder cancers. Due to its association with kidney and bladder cancers, we hypothesized that analysis of the urinary proteome could provide insight into the mechanisms of As toxicity. Urine from participants in a cross-sectional As biomarker study conducted in Nevada, classified as having either high (&gt;or= 100 microg total urinary As/l) or low exposure (&lt; 100 microg total urinary As/l) was analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Two polypeptides, 2.21 and 4.37 kDa, were significantly decreased in the high exposure group (p &lt; 0.05) and were limited to men when stratified by sex. To replicate these findings, urine from participants in a second As study in Chile was analyzed and results confirmed the decrease of the 4.37 kDa polypeptide as well as a 4.76 kDa polypeptide among highly exposed men. These peaks were identified and confirmed as human beta-defensin-1 (HBD-1) peptides. In a separate in vitro experiment, gene expression analysis of As-treated cell lines demonstrated reduced HBD1 mRNA confirming that the observed decrease in HBD-1 resulted from As exposure. HBD-1 is an antimicrobial peptide constitutively expressed in multiple tissues including epithelial cells of the respiratory and urogenital systems. Recent studies support its role as a tumor suppressor gene for urological cancers suggesting that decreased HBD-1 levels may play a role in the development of cancers associated with As exposure. Further studies are warranted to investigate the role of HBD-1 in As-related toxicity.",
Arsenic,1018615,"Effect of arsenic and cadmium on the persistence of mutagen-induced DNA lesions in human cells Abstract: The alkaline single cell gel electrophoresis (SCG test or comet assay) was used to characterize the influence of sodium arsenite (NaAsO2) and cadmium sulphate (CdSO4) on the persistence of mutagen-induced DNA lesions. Human blood and SV4O-transformed fibroblasts (MRC5CV1) were treated for 2 hr with methyl methanesulphonate (MMS) or benzo(a)pyrene (BaP). MMS induced concentration-related DNA damage in white Blood cells (WBC) and fibroblasts in similar concentrations. For the induction of DNA damage in white blood cells (WBC) and fibroblasts in similar concentrations. For the induction of DNA damage by BaP, higher concentrations had to be applied to WBC than to the fibroblast cell line. To study the influence of metal ions on the persistence of DNA lesions, treated cells were further incubated for 2 hr in the absence (postincubation) or presence (posttreatment) of NaAsO2 or CdSO4. After postincubation, MMS and BaP-induced DNA effects were reduced in both cell types, indicating that repair of DNA lesions had taken place. When the cells were posttreated with NaAsO2 or CdSO4, BaP- and MMS-induced DNA lesions persisted in both cell types, indicating an inhibition of DNA repair by these metals. The results suggest a strong interaction of arsenic and cadmium with BaP- and MMS-induced DNA repair processes.",
Arsenic,711013,"Pre- and postnatal arsenic exposure and child development at 18 months of age: A cohort study in rural Bangladesh Abstract: Exposure to arsenic through drinking water has been associated with impaired cognitive function in school-aged children in cross-sectional studies; however, there are few longitudinal studies and little information on effects of exposure in early life when the brain is generally most vulnerable.<br /><br /> A longitudinal cohort study beginning in early pregnancy was conducted in rural Bangladesh, where arsenic concentrations in well water vary considerably. We assessed the effects of pre- and postnatal arsenic exposure on development of 2112 children at 18 months of age with Bayley Scales of Infant Development-II (mental and psychomotor development indices), Wolke's Behavior Rating Scale and maternal report of language. We related the measures of child development to arsenic concentrations in maternal urine in gestational weeks 9 and 30 and child's urinary arsenic at 18 months of age. Details of socio-economic background, home stimulation and anthropometric measurements of mothers and children were also available.<br /><br /> Median maternal urinary arsenic concentration averaged over early and late gestation was 96 µg/l, whereas children's urine contained 35 µg/l of arsenic. There was no significant effect of any of the arsenic exposure measures on any of the child development measures after controlling for social and economic confounders, child's age and sex.<br /><br /> Contrary to expectations, we found no indications of adverse effects of pre- or postnatal arsenic exposure on child development at 18 months. It remains possible that duration of exposure is critical and that effects will become apparent later in childhood.",
Arsenic,1020481,"Chemical bonding in hypervalent molecules: is the octet rule relevant? Abstract: The bonding in a large number of hypervalent molecules of P, As, S, Se, Te, Cl, and Br with the ligands F, Cl, O, CH(3), and CH(2) has been studied using the topological analysis of the electron localization function ELF. This function partitions the electron density of a molecule into core and valence basins and further classifies valence basins according to the number of core basins with which they have a contact. The number and geometry of these basins is generally in accord with the VSEPR model. The population of each basin can be obtained by integration, and so, the total population of the valence shell of an atom can be obtained as the sum of the populations of all the valence basins which share a boundary with its core basin. It was found that the population of the V(A, X) disynaptic basin corresponding to the bond, where A is the central atom and X the ligand, varies with the electronegativity of the ligand from approximately 2.0 for a weakly electronegative ligand such as CH(3) to less than 1.0 for a ligand such as F. We find that the total population of the valence shell of a hypervalent atom may vary from close to 10 for a period 15 element and close to 12 for a group 16 element to considerably less than 8 for an electronegative ligand such as F. For example, the phosphorus atom in PF(5) has a population of 5.37 electrons in its valence shell, whereas the arsenic atom in AsMe5 has a population of 9.68 electrons in its valence shell. By definition, hypervalent atoms do not obey the Lewis octet rule. They may or may not obey a modified octet rule that has taken the place of the Lewis octet rule in many recent discussions and according to which an atom in a molecule always has fewer than 8 electrons in its valence shell. We show that the bonds in hypervalent molecules are very similar to those in corresponding nonhypervalent (Lewis octet) molecules. They are all polar bonds ranging from weakly to strongly polar depending on the electronegativity of the ligands. The term hypervalent therefore has little significance except to indicate that an atom in a molecule is forming more than four electron pair bonds.",
Arsenic,2336877,"Trace metals in size-fractionated particulate matter in a Portuguese hospital: Exposure risks assessment and comparisons with other countries Abstract: Hospitals are considered as a special and important type of indoor public place where air quality has significant impacts on potential health outcomes. Information on indoor air quality of these environments, concerning exposures to particulate matter (PM) and related toxicity, is limited though. This work aims to evaluate risks associated with inhalation exposure to ten toxic metals and chlorine (As, Ni, Cr, Cd, Pb, Mn, Se, Ba, Al, Si, and Cl) in coarse (PM2.5-10) and fine (PM2.5) particles in a Portuguese hospital in comparison with studies representative of other countries. Samples were collected during 1 month in one urban hospital; elemental PM characterization was determined by proton-induced X-ray emission. Noncarcinogenic and carcinogenic risks were assessed according to the methodology provided by the United States Environmental Protection Agency (USEPA; Region III Risk-Based Concentration Table) for three different age categories of hospital personnel (adults, &gt;20, and &lt;65 years) and patients (considering nine different age groups, i.e., children of 1-3 years to seniors of &gt;65 years). The estimated noncarcinogenic risks due to occupational inhalation exposure to PM2.5-bound metals ranged from 5.88?×?10(-6) for Se (adults, 55-64 years) to 9.35?×?10(-1) for As (adults, 20-24 years) with total noncarcinogenic risks (sum of all metals) above the safe level for all three age categories. As and Cl (the latter due to its high abundances) were the most important contributors (approximately 90 %) to noncarcinogenic risks. For PM2.5-10, noncarcinogenic risks of all metals were acceptable to all age groups. Concerning carcinogenic risks, for Ni and Pb, they were negligible (&lt;1?×?10(-6)) in both PM fractions for all age groups of hospital personnel; potential risks were observed for As and Cr with values in PM2.5 exceeding (up to 62 and 5 times, respectively) USEPA guideline across all age groups; for PM2.5-10, increased excess risks of As and Cr were observed particularly for long-term exposures (adults, 55-64 years). Total carcinogenic risks highly (up to 67 times) exceeded the recommended level for all age groups, thus clearly showing that occupational exposure to metals in fine particles pose significant risks. If the extensive working hours of hospital medical staff were considered, the respective noncarcinogenic and carcinogenic risks were increased, the latter for PM2.5 exceeding the USEPA cumulative guideline of 10(-4). For adult patients, the estimated noncarcinogenic and carcinogenic risks were approximately three times higher than for personnel, with particular concerns observed for children and adolescents.",
Arsenic,2347569,"Semi-quantification of pneumothorax volume by lung ultrasound Abstract: <strong>BACKGROUND: </strong>Lung ultrasound (LUS) may accurately diagnose pneumothorax. However, there is uncertainty about its usefulness in the quantification of pneumothorax size. To determine the ability of LUS in the semi-quantification of pneumothorax volume, we compared the projection of the lung point (LP) with the pneumothorax volume measured by computerized tomography (CT) and the interpleural distance on chest radiography (CXR).<br /><br /><strong>METHODS: </strong>We performed LUS in patients with pneumothorax and all the LP located on the chest wall were compared to CXR and CT studies. The primary outcome of the study was the ability of LP to grade pneumothorax volumes measured by CT. The secondary outcome was the accuracy of LP to predict small and large pneumothorax according to the societal guidelines based on CXR reading.<br /><br /><strong>RESULTS: </strong>A total of 124 patients with pneumothorax were enrolled (76 spontaneous, 20 traumatic and 28 post-procedural). Ninety-four CXR and 58 CT were available for the analysis. An LP posterior to the mid axillary line corresponded to three different CXR criteria for large pneumothorax with sensitivity from 81.4 to 88.2 % and specificity from 64.7 to 72.6 %. The mid axillary line also represented the limit for predicting greater than 15 % of lung collapse when volume is measured at CT, with sensitivity 83.3 % and specificity 82.4 %.<br /><br /><strong>CONCLUSIONS: </strong>LUS-targeted assessment of LP was a useful predictor of pneumothorax volume in this research study setting. LUS reliably classified pneumothorax size when compared to criteria based on CXR reading, particularly the small sized pneumothorax. However, LUS greatly outperformed conventional CXR reading for a graded quantification of the percentage of lung collapse.",
Arsenic,1337685,"Occurrence and sorption properties of arsenicals in marine sediments Abstract: The content of total arsenic, the inorganic forms: arsenite (As(III)) and arsenate (As(V)), the methylated forms: monomethylarsonic acid and dimethylarsinic acid (DMA), trimethylarsenic oxide, tetramethylarsenonium ion and arsenobetaine was measured in 95 sediment samples and 11 pore water samples from the Baltic Sea near the island of Bornholm at depths of up to 100 m. As(III+V) and DMA were detected in the sediment and As(III+V) was detected in the sediment pore water. Average total As concentration of 10.6?±?7.4 mg/kg dry matter (DM) in the sediment corresponds to previously reported values in the Baltic Sea and other parts of the world. Existing data for on-site measurements of sorption coefficients (Kd) of arsenicals in marine and freshwater sediments show large variability from &lt;1 to &gt;1,000 L/kg. In this work, calculated sorption coefficients (Kd and Koc) for As(III+V) showed significant correlation with depth, dissolved oxygen (DO), salinity and sediment classification; for depths &lt;70 m, salinity &lt;11 %, DO &gt;9 mg/L and sand/silt/clay sediments the Kd was 118?±?76 L/kg DM and for depths &gt;70 m, salinity &gt;11 %, DO?&lt;?9 mg/L and muddy sediments the Kd was 513?±?233 L/kg DM. The authors recommend using the found Kd value for arsenic in marine sediments when conditions are similar to the Baltic Sea. At locations with significant anthropogenic point sources or where the local geology contains volcanic rock and sulphide mineral deposits, there may be significantly elevated arsenic concentrations, and it is recommended to determine on-site Kd values.",
Arsenic,2278383,"Geographic variation in liver metal concentrations of greater sage-grouse Abstract: Populations of greater sage-grouse (Centrocercus urophasianus) have declined throughout the species' range. We evaluated metal concentrations in livers sampled from greater sage-grouse collected from hunters in Eureka County, Nevada, during autumn of 2008 and 2010. We make local comparisons of metal concentrations between two populations of greater sage-grouse in Eureka County, as well as regional comparisons with previously reported values for greater sage-grouse collected in Wyoming and Montana. With one exception, tissue concentrations of lead, arsenic, and mercury were below method detection limits. Mean concentrations of iron, molybdenum, and zinc differed between the two Nevada populations, and magnesium, cadmium, molybdenum, and selenium differed between greater sage-grouse in eastern Nevada, and values reported for Wyoming and Montana. In contrast, we found no evidence for local variation in magnesium, copper, cadmium, or selenium, or for regional variation in iron, zinc, or copper. Of particular interest were low selenium concentrations in our study system relative to Wyoming and Montana. Some individuals in our study returned liver selenium values considered consistent with selenium deficiency in domestic poultry. This research adds to the small body of literature on background contaminant levels in greater sage-grouse, and provides evidence for geographic variation in metal concentrations at local and regional scales.",
Arsenic,1677298,"A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation Abstract: Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1h ON, 1h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency.",
Arsenic,2220013,"Urinary excretion of arsenic metabolites after long-term oral administration of various arsenic compounds to rats Abstract: The metabolism of arsenic compounds in rats was studied by comparing urinary metabolites of arsenic compounds administered for 1 wk or 7 mo. Male F344/DuCrj rats were given 100 mg As/L as monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), or arsenobetaine (AsBe), or 10 mg As/L as arsenite [As(III)] via drinking water for 7 mo. Urine was collected by forced urination after 1 wk or 7 mo. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry. In the case of As(III) ingestion, a small portion of all arsenic excreted in urine (about 6%) was excreted in inorganic form, while most arsenic was excreted as methylated arsenic metabolites. Following MMA treatments for 1 wk or 7 mo, the predominant products excreted were unchanged MMA and DMA accompanied by small amounts of TMAO and tetramethylarsonium (TeMA). In the case of DMA treatment the urinary compounds found were mainly the parent DMA and TMAO with minute amounts of TeMA. TMAO was methylated to TeMA to a slight extent after 1 wk and 7 mo of administration, although most TMAO was excreted in the form of unchanged TMAO. AsBe was predominantly eliminated in urine without any transformation. Two unidentified metabolites were detected in urine after 7 mo of arsenic species exposure; the amounts of these metabolites increased in the order DMA &gt; MMA &gt; TMAO with only small quantities of these detected in the As(III)-treated group. These results suggest that these unidentified metabolites are formed during a demethylation process, and not during methylation. Our findings indicate that long-term exposure to As(III), MMA, or DMA decreases the proportion of TMAO elimination in urine and increases that of DMA, M-1, and M-2, and that further methylation to TMAO to TeMA does occur to a slight extent following long-term exposure to arsenical compounds in rats.",
Arsenic,1029072,"Carbon and arsenic metabolism in Thiomonas strains: Differences revealed diverse adaptation processes Abstract: BACKGROUND: Thiomonas strains are ubiquitous in arsenic-contaminated environments. Differences between Thiomonas strains in the way they have adapted and respond to arsenic have never been studied in detail. For this purpose, five Thiomonas strains, that are interesting in terms of arsenic metabolism were selected: T. arsenivorans, Thiomonas spp. WJ68 and 3As are able to oxidise As(III), while Thiomonas sp. Ynys1 and T. perometabolis are not. Moreover, T. arsenivorans and 3As present interesting physiological traits, in particular that these strains are able to use As(III) as an electron donor. RESULTS: The metabolism of carbon and arsenic was compared in the five Thiomonas strains belonging to two distinct phylogenetic groups. Greater physiological differences were found between these strains than might have been suggested by 16S rRNA/rpoA gene phylogeny, especially regarding arsenic metabolism. Physiologically, T. perometabolis and Ynys1 were unable to oxidise As(III) and were less arsenic-resistant than the other strains. Genetically, they appeared to lack the aox arsenic-oxidising genes and carried only a single ars arsenic resistance operon. Thiomonas arsenivorans belonged to a distinct phylogenetic group and increased its autotrophic metabolism when arsenic concentration increased. Differential proteomic analysis revealed that in T. arsenivorans, the rbc/cbb genes involved in the assimilation of inorganic carbon were induced in the presence of arsenic, whereas these genes were repressed in Thiomonas sp. 3As. CONCLUSION: Taken together, these results show that these closely related bacteria differ substantially in their response to arsenic, amongst other factors, and suggest different relationships between carbon assimilation and arsenic metabolism.",
Arsenic,2279110,"Microbial ecology of arsenic-mobilizing Cambodian sediments: lithological controls uncovered by stable-isotope probing Abstract: Microbially mediated arsenic release from Holocene and Pleistocene Cambodian aquifer sediments was investigated using microcosm experiments and substrate amendments. In the Holocene sediment, the metabolically active bacteria, including arsenate-respiring bacteria, were determined by DNA stable-isotope probing. After incubation with (13) C-acetate and (13) C-lactate, active bacterial community in the Holocene sediment was dominated by different Geobacter spp.-related 16S rRNA sequences. Substrate addition also resulted in the enrichment of sequences related to the arsenate-respiring Sulfurospirillum spp. (13) C-acetate selected for ArrA related to Geobacter spp. whereas (13) C-lactate selected for ArrA which were not closely related to any cultivated organism. Incubation of the Pleistocene sediment with lactate favoured a 16S rRNA-phylotype related to the sulphate-reducing Desulfovibrio oxamicus?DSM1925, whereas the ArrA sequences clustered with environmental sequences distinct from those identified in the Holocene sediment. Whereas limited As(III) release was observed in Pleistocene sediment after lactate addition, no arsenic mobilization occurred from Holocene sediments, probably because of the initial reduced state of As, as determined by X-ray Absorption Near Edge Structure. Our findings demonstrate that in the presence of reactive organic carbon, As(III) mobilization can occur in Pleistocene sediments, having implications for future strategies that aim to reduce arsenic contamination in drinking waters by using aquifers containing Pleistocene sediments.",
Arsenic,1026107,"The source of naturally occurring arsenic in a coastal sand aquifer of eastern Australia Abstract: The discovery of dissolved arsenic in a coastal aquifer used extensively for human consumption has led to widespread concern for its potential occurrence in other sandy coastal environments in eastern Australia. The development of an aquifer specific geomorphic model (herein) suggests that arsenic is regionally derived from erosion of arsenic-rich stibnite (Sb(2)S(3)) mineralisation present in the hinterland. Fluvial processes have transported the eroded material over time to deposit an aquifer lithology elevated in arsenic. Minor arsenic contribution to groundwater is derived from mineralised bedrock below the unconsolidated aquifer. An association with arsenic and pyrite has been observed in the aquifer in small discrete arsenian pyrite clusters rather than actual acid sulfate soil horizons. This association is likely to influence arsenic distribution in the aquifer, but is not the dominant control on arsenic occurrence. Arsenic association with marine clays is considered a function of their increased adsorptive capacity for arsenic and not solely on the influence of sea level inundation of the aquifer sediments during the Quaternary Period. These findings have implications for, but are not limited to, coastal aquifers. Rather, any aquifer containing sediments derived from mineralised provenances may be at risk of natural arsenic contamination. Groundwater resource surveys should thus incorporate a review of the aquifer source provenance when assessing the likely risk of natural arsenic occurrence in an aquifer.",
Arsenic,1328503,"Cross-linking of surface IgM in the Burkitt's lymphoma cell line ST486 provides protection against arsenite- and stress-induced apoptosis that is mediated by ERK and phosphoinositide 3-kinase signaling pathways Abstract: The ST486 cell line, derived from a human Burkitt's lymphoma, is a model for antigen-induced clonal deletion in germinal center B-lymphocytes, with apoptosis induced upon cross-linking of surface IgM. Moreover, this cell line is highly sensitive to the induction of apoptosis by many chemicals, including sodium arsenite, a significant environmental contaminant with immunotoxic activity. In contrast to arsenite and other chemicals, surface IgM cross-linking induces apoptosis in ST486 cells with delayed kinetics. Moreover, the initial signaling events following IgM stimulation are associated with cell survival and proliferation and include activation of the extracellular-signal regulated kinase (ERK) and the phosphoinositide 3-kinase (PI3K) pathways. We examined the question of whether IgM-mediated activation of the ERK and PI3K pathways can influence the apoptotic response of ST486 cells following exposure to arsenite and selected drugs with different molecular targets, including cycloheximide, etoposide, and camptothecin, and a physical stress, hyperthermia. Our findings show that IgM-stimulated cells are significantly protected against arsenite and drug-induced apoptosis during a window of several hours after surface IgM cross-linking, as evidenced by an inhibition of cleavage of poly(ADP-ribose) polymerase and lack of morphological changes indicative of apoptosis. Significantly, surface IgM cross-linking also protects against arsenite-induced mitochondrial depolarization as well as caspase-9 cleavage. Furthermore, we demonstrate that this IgM-mediated protection requires the activation of the ERK and PI3K pathways, because inhibition of either pathway blocks the ability of antigen receptor activation to protect against apoptosis. Our study also provides evidence for p90(S6) ribosomal kinase as a point of convergence between the two signaling pathways resulting in the phosphorylation of the pro-apoptotic Bcl-2 family member Bad at serine 112. This investigation demonstrates, for the first time, that specific signals transduced by activation of the B-cell receptor protect cells at a common point of regulation in the apoptotic pathways for diverse stresses.",
Arsenic,568930,"The role of protein binding of trivalent arsenicals in arsenic carcinogenesis and toxicity Abstract: Three of the most plausible biological theories of arsenic carcinogenesis are protein binding, oxidative stress and altered DNA methylation. This review presents the role of trivalent arsenicals binding to proteins in arsenic carcinogenesis. Using vacuum filtration based receptor dissociation binding techniques, the lifetimes of unidentate (<1Â s), bidentate (1-2Â min) and tridentate (1-2Â h) arsenite containing peptide binding complexes were estimated. According to our experimental data some of the protein targets to which arsenite may bind in vivo include tubulin, poly(ADP-ribose)polymerase (PARP-1), thioredoxin reductase, estrogen receptor-alpha, arsenic(+3)methyltransferase and Keap-1. Arsenite binding to tubulin can lead to several of the genetic effects observed after arsenic exposures (aneuploidy, polyploidy and mitotic arrests). Among many other possible arsenite binding sites are rat hemoglobin, the DNA repair enzyme xeroderma pigmentosum protein A (XPA), and other C2H2, C3H and C4 zinc finger proteins including members of the steroid receptor superfamily (e.g. glucocorticoid receptor). Macromolecules to which arsenite does not bind to include calf thymus DNA, mixed Type II-A histones and bovine H3/H4 histone. Although all six tested arsenicals released iron from ferritin, radioactive arsenite did not bind to the protein horse ferritin.",
Arsenic,759702,"Arsenic, stem cells, and the developmental basis of adult cancer Abstract: That chemical insults or nutritive changes during in utero and/or postnatal life can emerge as diseases much later in life are now being accepted as a recurring phenomenon. In this regard, inorganic arsenic is a multisite human carcinogen found at high levels in the drinking water of millions of people, although it has been difficult until recently to produce tumors in rodents with this metalloid. A mouse transplacental model has been developed where maternal exposure to inorganic arsenic either acts as a complete carcinogen or enhances carcinogenic response to other agents given subsequently in the offspring, producing tumors during adulthood. Similarly, human data now have emerged showing that arsenic exposure during the in utero period and/or in early life is associated with cancer in adulthood. The mouse arsenic transplacental model produces tumors or enhances response to other agents in multiple strains and tissues, including sites concordant with human targets of arsenic carcinogenesis. It is now believed that cancer often is a stem cell (SC)-based disease, and there is no reason to think cancer induced by developmental chemical exposure is any different. Indeed, arsenic impacts human SC population dynamics in vitro by blocking exit into differentiation pathways and whereby creating more key targets for transformation. In fact, during in vitro malignant transformation, arsenic causes a remarkable survival selection of SCs, creating a marked overabundance of cancer SCs (CSCs) compared with other carcinogens once a cancer phenotype is obtained. In addition, skin cancers produced following in utero arsenic exposure in mice are highly enriched in CSCs. Thus, arsenic impacts key, long-lived SC populations as critical targets to cause or facilitate later oncogenic events in adulthood as a possible mechanism of developmental basis of adult disease.",
Arsenic,1340123,"Effect of fishing vessels on trace metal contamination in sediments of three harbors along Iranian Oman Sea coast Abstract: In this study, the levels of natural and anthropogenic metal contamination (aluminum (Al), iron (Fe), manganese (Mn), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn)) in surface sediments of three harbors along the Iranian coast of Gulf of Oman were examined and reported for the first time. Effect of grain size, mineralogy, normalization technique using Fe concentrations, and different sediment quality guidelines were discussed. Data from the harbors were compared with other harbors worldwide. Sediments inside the harbors are characterized by moderate and high levels of pollution by trace metals Cu (12-287 ?g/g), Pb (11-1,780 ?g/g), Zn (38-547 ?g/g), Cr (70-2,370 ?g/g), and Ni (31-116 ?g/g). However, As and Cd did not show considerable pollution inside and outside the harbors. Considering that there is no industrial activity around the study harbors, the major sources of contamination in the harbors are repairing, fueling, greasing, and painting of fishing ships and boats. Mineralogy of sediments in the study area as well as trace metal concentration in reference samples taken from onshore geological units confirmed that natural inputs of Cd, Cu, Pb, and Zn in the harbors are very low while most of Ni and Cr contamination in the study area comes from erosion of ophiolitic mélange units at the North of Makran mountains.",
Arsenic,1021593,"Akt activation is responsible for enhanced migratory and invasive behavior of arsenic-transformed human bronchial epithelial cells Abstract: <strong>BACKGROUND: </strong>Arsenic is one of the most common environmental contaminants. Long-term exposure to arsenic causes human bronchial epithelial cell (HBEC) malignant transformation and lung cancer. However, the mechanism of arsenic lung carcinogenesis is not clear, and the migratory and invasive properties of arsenic-transformed cells (As-transformed cells) have rarely been studied.<br /><br /><strong>OBJECTIVES: </strong>This study was designed to investigate the migratory and invasive behavior of As-transformed HBECs and the underlying mechanism.<br /><br /><strong>METHODS: </strong>As-transformed p53lowHBECs were generated by exposing p53-knockdown HBECs to sodium arsenite (2.5 ?M) for 16 weeks. Cell migration was assessed by transwell migration and wound-healing assay. Cell invasion was evaluated using Matrigel-coated transwell chambers. Gene overexpression, small interfering RNA (siRNA) knockdowns, and pharmacological inhibitors were used to determine the potential mechanism responsible for enhanced cell migration and invasion.<br /><br /><strong>RESULTS: </strong>Transwell migration and invasion assays revealed that As-transformed p53lowHBECs were highly migratory and invasive. Akt (also known as protein kinase B) and extracellular signal-regulated protein kinase 1/2 (Erk1/2) were strongly activated in As-transformed p53lowHBECs. Stable expression of microRNA 200b in As-transformed p53lowHBECs abolished Akt and Erk1/2 activation and completely suppressed cell migration and invasion. Pharmacological inactivation of Akt but not Erk1/2 significantly decreased cell migration and invasion. Inhibition of Akt reduced the expression of epithelial-to-mesenchymal transition-inducing transcription factors zinc-finger E-box-binding homeobox factor 1 (ZEB1) and ZEB2. siRNA knockdown of ZEB1 and ZEB2 impaired As-transformed p53lowHBEC migration and invasion.<br /><br /><strong>CONCLUSIONS: </strong>Akt activation plays a critical role in enabling As-transformed HBEC migration and invasion by promoting ZEB1 and ZEB2 expression.",
Arsenic,1003631,"Isolation and characterization of aerobic culturable arsenic-resistant bacteria from surfacewater and groundwater of Rautahat District, Nepal Abstract: Arsenic (As) contamination of groundwater is a serious Environmental Health Management issue of drinking water sources especially in Terai region of Nepal. Many studies have reported that due to natural abundance of arsenic in the environment, various bacteria have developed different resistance mechanisms for arsenic compound. In this study, the culturable arsenic-resistant bacteria indigenous to surfacewater as well as groundwater from Rautahat District of Nepal were randomly isolated by standard plate count method on the basis of viable growth on plate count agar amended with arsenate ranging from 0, 0.5, 10, 40, 80 to 160 milligram per liter (mg/l). With respect to the morphological and biochemical tests, nine morphologically distinct potent arsenate tolerant bacteria showed relatedness with Micrococcus varians, Micrococcus roseus, Micrococcus luteus, Pseudomonas maltophilia, Pseudomonas sp., Vibrio parahaemolyticus, Bacillus cereus, Bacillus smithii 1 and Bacillus smithii 2. The isolates were capable of tolerating more than 1000 mg/l of arsenate and 749 mg/l of arsenite. Likewise, bioaccumulation capability was highest with M.roseus (85.61%) and the least with B.smithii (47.88%) indicating the potential of the organisms in arsenic resistance and most probably in bioremediation.",
Arsenic,1346552,"HCV proteins increase expression of heme oxygenase-1 (HO-1) and decrease expression of Bach1 in human hepatoma cells Abstract: <strong>BACKGROUND/AIMS: </strong>Hepatitis C infection induces hepatic oxidative stress. Heme oxygenase (HO), the rate-controlling enzyme of heme catabolism, plays a key role as a protector against oxidative, and other stresses. Other recent work has implicated Bach1, a heme binding protein that represses gene expression, in the regulation of HO-1 gene expression.<br /><br /><strong>METHODS: </strong>We investigated the effects of HCV polyprotein expression on expression of HO-1 and Bach1 genes in human hepatoma cells (Huh-7 cells).<br /><br /><strong>RESULTS: </strong>HO-1 was up-regulated in the cell line expressing HCV proteins from core up to the aminoterminal domain of NS3. Addition of increasing concentrations of N-acetylcysteine (NAC) led to down-regulation of HO-1 in cells expressing HCV proteins. In contrast, Bach1 was significantly down-regulated in these cells. Sodium arsenite, a strong inducer of oxidative stress and HO-1, reduced Bach1 expression in wild type Huh-7 cells, and NAC partially abrogated this decrease.<br /><br /><strong>CONCLUSIONS: </strong>Huh-7 cells expressing HCV proteins show significant up-regulation of the HO-1 gene, and reciprocal down-regulation of the Bach1 gene. Exogenous oxidative stressors and anti-oxidants can modulate expression of these genes. These and other results suggest a key role of down-regulation of Bach1 and up-regulation of HO-1 in diminishing cytotoxic effects of HCV proteins in human hepatocytes.",
Arsenic,1070312,"Diphenylarsinic Acid Increased the Synthesis and Release of Neuroactive and Vasoactive Peptides in Rat Cerebellar Astrocytes Abstract: ABSTRACT: An incident of poisoning occurred in Japan in 2003 when high-level contamination with arsenic, mainly diphenylarsinic acid (DPAA), was found in well water. People using this water particularly experienced cerebellar symptoms. In the present study, we investigated the adverse effects of DPAA on the cerebellum in vitro and in vivo to understand the biological mechanisms that cause cerebellar symptoms.Comprehensive gene expression analyses in primary cultured ratcerebellar cells exposed to 10 ?M DPAA for 24 hours indicated significant alterations in the mRNA expression of genes encoding antioxidative stress proteins (heme oxigenase 1 and heat shock protein72) and neuroactive and vasoactive peptides (neuropeptide Y, adrenomedullin, monocyte chemoattractant protein 1, and fibroblast growth factor 2). Further analyses of proteins revealed that cultured cerebellar astrocytes expressed these antioxidative stress proteins and peptides in response to exposure to DPAA. In addition, these adverseeffects were also observed in the cerebellum exposed in vivo to DPAA (100 mg/L) for 21 days. These results suggested that cerebellarastrocytes irregularly secrete neuroactive and vasoactive peptidesagainst DPAA-induced oxidative stress, which leads to abnormal neural functions and disrupted cerebellar autoregulation dynamics and results in the onset of cerebellar symptoms.",
Arsenic,628350,"Arsenic trioxide sensitivity is associated with low level of glutathione in cancer cells Abstract: Arsenic trioxide (As2O3) is a novel anticancer agent, which has been found to induce remission in acute promyelocytic leukaemic patients following daily intravenous administration. The therapeutic value of As2O3 in other cancers is still largely unknown. Cytotoxic tests in a panel of cancer cell lines showed that bladder cancer, acute promyelocytic leukaemic and gastrointestinal cancer cells were the most sensitive to As2O3 among 17 cell lines tested. Cellular glutathione (GSH) system plays an important role in arsenic detoxification in mammalian cells. Cancer cells that were intrinsically sensitive to As2O3 contained lower levels of GSH, whereas resistant cancer cells contained higher levels of GSH. On the other hand, there was no association of glutathione-S-transferase-? or multidrug resistance-associated protein 1 levels with arsenic sensitivity in these cancer cells. Multidrug-resistant cancer cells that were cross-resistant to arsenic contained higher levels of GSH or multidrug-resistance-associated protein 1 than their drug-sensitive parental cells. Cancer cells become more sensitive to arsenic after depletion of cellular GSH with L-buthionine sulphoximine. We concluded that cellular GSH level is the most important determinant of arsenic sensitivity in cancer cells. Cellular GSH level and its modulation by buthionine sulphoximine should be considered in designing clinical trials using arsenic in solid tumours.",
Arsenic,67294,"Inorganic arsenic effects on human lymphocyte stimulation and proliferation Abstract: Lymphocyte cultures from individuals exposed to high levels of hydroarsenicism showed a slower cell cycle kinetics than cultures from low-exposed individuals. Since this difference in proliferation could be due to chronic arsenic exposure, the in vitro effects of inorganic arsenic in human whole blood lymphocyte cultures were investigated. When lymphocytes were exposed to concentrations of arsenite and arsenate similar to those found in the blood of exposed subjects (10?7, 10?8 and 10?9 M) during the last 24 h before harvesting, a dose-related inhibition of proliferation was observed. Cultures were also treated with 10?9 M of arsenite and arsenate for 2, 6 and 24 h at the beginning of the cultures in the presence or absence of phytohemagglutinin (PHA). Inhibition of stimulation and proliferation was directly related to the length of treatment. The results show that, at the concentrations tested, arsenite and arsenate impair lymphocyte stimulation and poliferation and confirm the fact that chronic arsenic exposure can affect the proliferation of whole blood lymphocytes.",
Arsenic,2279475,"Comparison of the accuracy of kriging and IDW interpolations in estimating groundwater arsenic concentrations in Texas Abstract: Exposure to arsenic causes many diseases. Most Americans in rural areas use groundwater for drinking, which may contain arsenic above the currently allowable level, 10µg/L. It is cost-effective to estimate groundwater arsenic levels based on data from wells with known arsenic concentrations. We compared the accuracy of several commonly used interpolation methods in estimating arsenic concentrations in &gt;8000 wells in Texas by the leave-one-out-cross-validation technique. Correlation coefficient between measured and estimated arsenic levels was greater with inverse distance weighted (IDW) than kriging Gaussian, kriging spherical or cokriging interpolations when analyzing data from wells in the entire Texas (p&lt;0.0001). Correlation coefficient was significantly lower with cokriging than any other methods (p&lt;0.006) for wells in Texas, east Texas or the Edwards aquifer. Correlation coefficient was significantly greater for wells in southwestern Texas Panhandle than in east Texas, and was higher for wells in Ogallala aquifer than in Edwards aquifer (p&lt;0.0001) regardless of interpolation methods. In regression analysis, the best models are when well depth and/or elevation were entered into the model as covariates regardless of area/aquifer or interpolation methods, and models with IDW are better than kriging in any area/aquifer. In conclusion, the accuracy in estimating groundwater arsenic level depends on both interpolation methods and wells' geographic distributions and characteristics in Texas. Taking well depth and elevation into regression analysis as covariates significantly increases the accuracy in estimating groundwater arsenic level in Texas with IDW in particular.",
Arsenic,732021,"Long term low-dose arsenic exposure induces loss of DNA methylation Abstract: Arsenic ranks as the number one toxic environmental contaminant. In humans, arsenic exposure is associated with various forms of cancer, cardiovascular and skin diseases, neuropathies of the central nervous system, and genotoxic and immunotoxic effects. Although a well recognized human carcinogen, arsenic itself is not a potent mutagen and has been thought to act through epigenetic mechanisms that modify DNA methylation patterns, perhaps in conjunction with DNA-damaging agents. To develop preliminary support for a more thorough examination of this hypothesis, we have measured the effect of submicromolar and low-micromolar concentrations of arsenite on the methylation status of DNA and the biochemical reactions that regulate it. We find that arsenic causes the depletion of S-adenosylmethionine, the main cellular methyl donor, and represses the expression of the DNA methyltransferase genes DNMT1 and DNMT3A. Possibly as a consequence of these two complementary mechanisms, long-term exposure to arsenic results in DNA hypomethylation.",
Arsenic,1508883,"Sirtuin-4 modulates sensitivity to induction of the mitochondrial permeability transition pore Abstract: The sustained opening of the mitochondrial permeability transition pore (PTP) is a decisive event in the onset of irreversible cell injury. The PTP is modulated by numerous exogenous and endogenous effectors, including mitochondrial membrane potential, ions and metabolites. Mitochondrial sirtuins have recently emerged as pivotal mediators of mitochondrial metabolism. In the present study, we demonstrate that sirt-4 modulates sensitivity to PTP onset induced by calcium and the oxidative cross linking reagent phenylarsine oxide, and PTP dependent cytotoxicity brought about by TNF or doxorubicin. Moreover, the ability of sirt-4 to modulate onset of the PTP is dependent on the expression of glutamate dehydrogenase-1.",
Arsenic,2149141,"Republished: Environmental and occupational exposure to chemicals and telomere length in human studies Abstract: Telomeres are complexes of tandem repeats of DNA (5'-TTAGGG-3') and protein that cap eukaryotic chromosomes and play a critical role in chromosome stability. Telomeres shorten with aging and this process can be accelerated by increased oxidative stress and episodes of inflammation. Evidence is rapidly growing that telomere length (TL) may be affected by environmental chemicals that have frequently been associated with chronic diseases. In this article, we review the published data on TL in relation to environmental and occupational exposure to several chemicals based on our own and others' studies. The environmental and occupational exposures associated with shorter TL include traffic-related air pollution (ie, particulate matter (PM), black carbon (BC), and benzene and toluene), polycyclic aromatic hydrocarbons (PAHs), N-nitrosamines, pesticides, lead, exposure in car mechanical workshops, and hazardous waste exposure. Arsenic, persistent organic pollutants (POPs) and short-term exposure to PM are associated with longer TL. We discuss the possible reasons for the differences in results, including time- and dose-related issues, study design, and possible mechanisms involved in telomere regulation. We also discuss the future directions and challenges for TL-related environmental and occupational health research, such as investigation of TL in subpopulations of blood leukocytes, and the study of genetic and epigenetic factors that may regulate telomere integrity using longitudinal designs.",
Arsenic,657850,"Determinants of arsenic metabolism: Blood arsenic metabolites, plasma folate, cobalamin, and homocysteine concentrations in maternal-newborn pairs Abstract: BACKGROUND: In Bangladesh, tens of millions of people have been consuming waterborne arsenic for decades. The extent to which As is transported to the fetus during pregnancy has not been well characterized. OBJECTIVES: We therefore conducted a study of 101 pregnant women who gave birth in Matlab, Bangladesh. METHODS: Maternal and cord blood pairs were collected and concentrations of total As were analyzed for 101 pairs, and As metabolites for 30 pairs. Maternal urinary As metabolites and plasma folate, cobalamin, and homocysteine levels in maternal cord pairs were also measured. Household tube well-water As concentrations exceeded the World Health Organization guideline of 10 microg/L in 38% of the cases. RESULTS: We observed strong associations between maternal and cord blood concentrations of total As (r = 0.93, p < 0.0001). Maternal and cord blood arsenic metabolites (n = 30) were also strongly correlated: in dimethylarsinate (DMA) (r = 0.94, p < 0.0001), monomethylarsonate (r = 0.80, p < 0.0001), arsenite (As(+3)) (r = 0.80, p < 0.0001), and arsenate (As(+5)) (r = 0.89, p < 0.0001). Maternal homocysteine was a strong predictor of %DMA in maternal urine, maternal blood, and cord blood (beta = -6.2, p < 0.02; beta = -10.9, p < 0.04; and beta = -13.7, p < 0.04, respectively). Maternal folate was inversely associated with maternal blood As(5+) (beta = 0.56, p < 0.05), and maternal cobalamin was inversely associated with cord blood As(5+) (beta = -1.2, p < 0.01). CONCLUSIONS: We conclude that exposure to all metabolites of inorganic As occurs in the prenatal period.",
Arsenic,1677585,"Bipolar mass spectrometry of labile coordination complexes, redox active inorganic compounds, and proteins using a glass nebulizer for sonic-spray ionization Abstract: In this study, we report on the development of a novel nebulizer configuration for sonic-spray ionization (SSI) mass spectrometry (MS), more specifically for a version of SSI that is referred to as Venturi easy ambient sonic-spray ionization (V-EASI) MS. The developed nebulizer configuration is based on a commercially available pneumatic glass nebulizer that has been used extensively for aerosol formation in atomic spectrometry. In the present study, the nebulizer was modified in order to achieve efficient V-EASI-MS operation. Upon evaluating this system, it has been demonstrated that V-EASI-MS offers some distinct advantages for the analysis of coordination compounds and redox active inorganic compounds over the predominantly used electrospray ionization (ESI) technique. Such advantages, for this type of compounds, are demonstrated here for the first time. More specifically, a series of labile heptanuclear heterometallic [Cu(II) 6Ln(III)] clusters held together with artificial amino acid ligands, in addition to easily oxidized inorganic oxyanions of selenium and arsenic, were analyzed. The observed advantages pertain to V-EASI appearing to be a &quot;milder&quot; ionization source than ESI, not requiring electrical potentials for gas phase ion formation, thus eliminating the possibility of unwanted redox transformations, allowing for the &quot;simultaneous&quot; detection of negative and positive ions (bipolar analysis) without the need to change source ionization conditions, and also not requiring the use of syringes and delivery pumps. Because of such features, especially because of the absence of ionization potentials, EASI can be operated with minimal requirements for source parameter optimization. We observed that source temperature and accelerating voltage do not seem to affect labile compounds to the extent they do in ESI-MS. In addition, bipolar analysis of proteins was demonstrated here by acquiring both positive and negative ion mass spectra from the same protein solutions, without the need to independently adjust solution and source conditions in each mode. Finally, the simple and efficient operation of a dual-nebulizer configuration was demonstrated for V-EASI-MS for the first time.",
Arsenic,1350182,Rapid Analysis of Elemental Concentrations in Compost Via Portable X-ray Fluorescence Spectrometry Abstract: ,
Arsenic,1015912,"Phytoremediation of arsenic in submerged soil by wetland plants Abstract: Wetland aquatic plants including Canna glauca L., Colocasia esculenta L. Schott, Cyperus papyrus L. and Typha angustifolia L. were used in the phytoremediation of submerged soil polluted by arsenic (As). Cyperus papyrus L. was noticed as the largest biomass producer which has arsenic accumulation capacity of 130-172 mg As/kg plant. In terms of arsenic removal rate, however, Colocasia esculenta L. was recognized as the largest and fastest arsenic remover in this study. Its arsenic removal rate was 68 mg As/m2/day while those rates of Canna glauca L., Cyperus papyrus L. and Typha angustifolia L. were 61 mg As/m2/day, 56 mg As/m2/day, and 56 mg As/m2/day, respectively. Although the 4 aquatic plants were inferior in arsenic accumulation, their high arsenic removal rates were observed. Phytostabilization should be probable for the application of these plants.",
Arsenic,627021,"Trolox selectively enhances arsenic-mediated oxidative stress and apoptosis in APL and other malignant cell lines Abstract: Although arsenic trioxide (As2O3) is an effective therapy in acute promyelocytic leukemia (APL), its use in other malignancies is limited by the toxicity of concentrations required to induce apoptosis in non-APL tumor cells. We looked for agents that would synergize with As2O3 to induce apoptosis in malignant cells, but not in normal cells. We found that trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), a widely known antioxidant, enhances As2O3-mediated apoptosis in APL, myeloma, and breast cancer cells. Treatment with As2O3 and trolox increased intracellular oxidative stress, as evidenced by heme oxygenase-1 (HO-1) protein levels, c-Jun terminal kinase (JNK) activation, and protein and lipid oxidation. The synergistic effects of trolox may be specific to As2O3, as trolox does not add to toxicity induced by other chemotherapeutic drugs. We explored the mechanism of this synergy using electron paramagnetic resonance and observed the formation of trolox radicals when trolox was combined with As2O3, but not with doxorubicin. Importantly, trolox protected nonmalignant cells from As2O3-mediated cytotoxicity. Our data provide the first evidence that trolox may extend the therapeutic spectrum of As2O3. Furthermore, the combination of As2O3 and trolox shows potential specificity for tumor cells, suggesting it may not increase the toxicity associated with As2O3 monotherapy in vivo.",
Arsenic,1380538,"Phenylarsine oxide and ethanol prevent cell death of porcine polymorphonuclear leucocytes induced by phorbol myristate acetate Abstract: In this study, we report that phenylarsine oxide and ethanol, both of which suppress a number of polymorphonuclear leucocyte functions including superoxide production, prevented the phorbol myristate acetate-induced cell death in a dose-dependent manner. These reagents had an inhibitory effect even after polymorphonuclear leucocytes were stimulated to produce superoxide by treatment with phorbol myristate acetate. The results indicate that activation of protein kinase C and subsequent superoxide release do not directly cause phorbol myristate acetate-induced cell death. Phenylarsine oxide or ethanol prevents cell death by affecting pathways downstream from those involved in the superoxide production.",
Arsenic,2278467,"Using biofilm as a novel approach to assess stormwater treatment efficacy Abstract: Contaminants associated with stormwater are among the leading causes of water quality impairment in urban streams. Multiple device treatment systems are commonly installed with the aim of reducing contaminant loads within stormwater discharge. However, the in situ performance of such systems remains poorly understood. We investigated the efficacy of an advanced stormwater treatment system by monitoring biofilm associated metals and biofilm bacterial community composition at multiple locations through the treatment system (which included rain gardens, grassy swales, a stormwater filter and a wetland) and in the receiving stream above and below the stormwater discharge. Changes in bacterial community composition were assessed by Automated Ribosomal Intergenic Spacer Analysis (ARISA) and concentrations of biofilm associated metals monitored by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Significant differences in bacterial community composition were detected throughout the stormwater network. Bacterial communities gradually changed towards a community more similar to that within the receiving stream and the discharge of treated stormwater had little effect on the composition of bacterial communities in the receiving stream, suggesting the effective conditioning of water quality by the treatment system. Concentrations of some biofilm-associated metals declined following sequential treatment, for example copper (73% reduction), zinc (48% reduction) and lead (46% reduction). In contrast, levels of arsenic, cadmium, chromium and nickel were not reduced by the treatment system. We demonstrate that biofilm bacterial community composition is a sensitive indicator of environmental changes within freshwater ecosystems and an efficient indicator to monitor water quality in enclosed stormwater networks where traditional biological indicators are not available.",
Arsenic,1020666,"Dimethylthioarsenicals as arsenic metabolites and their chemical preparations Abstract: Two unidentified arsenic metabolites were detected in the liver of rats on a gel filtration column by HPLC inductively coupled argon plasma mass spectrometry after an injection of dimethylarsinic (DMA(V)), dimethylarsinous (DMA(III)), monomethylarsonic (MMA(V)), or monomethylarsonous (MMA(III)) acid. The same arsenicals were also produced in vitro by incubation of DMA(III) in the liver supernatant but not by DMA(V). The two arsenic metabolites eluted at the same retention times as those of the two arsenicals prepared by reaction of DMA(V) with either thiosulfate plus disulfite or hydrogen sulfide or sodium sulfide plus sulfuric acid. The faster and slower eluting products on a gel filtration column were assigned as dimethyldithioarsinic acid (dimethylarsinodithioic acid) (DMTA(V)) and dimethylthioarsinous acid (DMTA(III)) from mass spectrometric data at m/z = 170 and 138 by electrospray ionization mass spectrometry with negative and positive ion modes, respectively. They were prepared selectively by reacting DMA(V) with hydrogen sulfide or sodium sulfide plus sulfuric acid under different reaction conditions. DMA(III) but not DMA(V) was transformed to DMTA(III) and DMTA(V) in the presence of sodium sulfide in vitro, suggesting that DMA(V) is reduced to DMA(III) with hydrogen sulfide, thiolated to DMTA(III), and then further thiolated oxidatively to DMTA(V). Metabolically, it is assumed that DMA(III) is transformed to DMTA(III) in the presence of sulfide ions, and then, DMTA(III) is oxidatively thiolated to DMTA(V). As the chemical species produced by reduction with the Reay and Asher method are DMTA(III) and DMTA(V), and different from DMA(III), the studies carried out with DMA(III) with the Reay and Asher method have to be reexamined.",
Arsenic,656913,"Curcumin supplementation protects from genotoxic effects of arsenic and fluoride Abstract: The present study was aimed to evaluate curcumin as a potential natural antioxidant to mitigate the genotoxic effects of arsenic (As) and fluoride (F) in human peripheral blood lymphocytes. The study was divided into nine groups consisting of negative control, positive control treated with ethyl methane sulphonate (EMS; 1.93 mM) and curcumin control with only curcumin (1.7 microM) in blood culture. As (1.4 microM) and F (34 microM) were added alone as well as in combination, to the cultures, with and without curcumin. Cultures were analysed for chromosomal aberrations (both structural and numerical) and primary DNA damage via comet assay as the genotoxic parameters after an exposure duration of 24h. Results revealed that curcumin efficiently ameliorates the toxic effect of As and F by reducing the frequency of structural aberrations (>60%), hypoploidy (>50%) and primary DNA damage. In conclusion, curcumin mitigates the genotoxic effects of the two well known water contaminants (As and F) effectively and efficiently at the given concentration in vitro.",
Arsenic,1337384,"Step-wise kinetics of natural physical ageing in arsenic selenide glasses Abstract: The long-term kinetics of physical ageing at ambient temperature is studied in Se-rich As-Se glasses using the conventional differential scanning calorimetry technique. It is analysed through the changes in the structural relaxation parameters occurring during the glass-to-supercooled liquid transition in the heating mode. Along with the time dependences of the glass transition temperature (T(g)) and partial area (A) under the endothermic relaxation peak, the enthalpy losses (?H) and calculated fictive temperature (T(F)) are analysed as key parameters, characterizing the kinetics of physical ageing. The latter is shown to have step-wise character, revealing some kinds of subsequent plateaus and steep regions. A phenomenological description of physical ageing in the investigated glasses is proposed on the basis of an alignment-shrinkage mechanism and first-order kinetic equations.",
Arsenic,1025314,"Market basket survey shows elevated levels of As in South Central U.S. processed rice compared to California: Consequences for human dietary exposure Abstract: We report the largest market basket survey of arsenic (As) in U.S. rice to date. Our findings show differences in transitional-metal levels between polished and unpolished rice and geographical variation in As and selenium (Se) between rice processed in California and the South Central U.S. The mean and median As grain levels for the South Central U.S. were 0.30 and 0.27 mimcrog As g(-1), respectively, for 107 samples. Levels for California were 41% lower than the South Central U.S., with a mean of 0.17 microg As g(-1) and a median of 0.16 microg As g(-1) for 27 samples. The mean and median Se grain levels for the South Central U.S. were 0.19 microg Se g(-1). Californian rice levels were lower, averaging only 0.08 and 0.06 microg Se g(-1) for mean and median values, respectively. The difference between the two regions was found to be significant for As and Se (General Linear Model (GLM): As p &lt; 0.001; Se p &lt; 0.001). No statistically significant differences were observed in As or Se levels between polished and unpolished rice (GLM: As p= 0.213; Se p= 0.113). No significant differences in grain levels of manganese (Mn), cobalt (Co), copper (Cu), or zinc (Zn) were observed between California and the South Central U.S. Modeling arsenic intake for the U.S. population based on this survey shows that for certain groups (namely Hispanics, Asians, sufferers of Celiac disease, and infants) dietary exposure to inorganic As from elevated levels in rice potentially exceeds the maximum intake of As from drinking water (based on consumption of 1 L of 0.01 mg L(-1) In. As) and Californian state exposure limits. Further studies on the transformation of As in soil, grain As bioavailability in the human gastrointestinal tract, and grain elemental speciation trends are critical.",
Arsenic,2064185,Synthesis of mesoporous maghemite (gamma-Fe2O3) nanostructures with enhanced arsenic removal efficiency Abstract: ,
Arsenic,2278468,"The role of Mn oxide doping in phosphate removal by Al-based bimetal oxides: Adsorption behaviors and mechanisms Abstract: This study investigated the behaviors and mechanisms of phosphate adsorbed onto manganese (Mn) oxide-doped aluminum (Al) oxide (MODAO). The isotherm results demonstrated that the maximum amount of phosphorus (P) adsorbed onto MODAO was 59.8 mg/g at T=298 K (pH 6.0). This value was nearly twice the amount of singular AlOOH and could increase with rising temperatures. The kinetic results illustrated that most of the P was adsorbed onto MODAO within 5 h, which was shorter than the equilibrium time of phosphate adsorption onto AlOOH. The Elovich model effectively described the adsorption kinetic data of MODAO because of its heterogeneous surface. The optimal solution pH for phosphate removal was approximately 5.0 because of electrostatic interaction effects. Meanwhile, the decrease in P uptake with increasing ion strength suggested that phosphate adsorption occurred through an outer-sphere complex. Phosphates would compete for adsorption sites on the surface of MODAO in the presence of fluoride ion or sulfate. In addition, the spectroscopic analysis results of Fourier transform infrared spectroscopy and X-ray photoemission spectroscopy indicated that removal mechanisms of phosphate primarily include adhesion to surface hydroxyl groups and ligand exchange.",
Arsenic,737374,"Effect of arsenite on the DNA repair of UV-irradiated Chinese hamster ovary cells Abstract: Arsenite, an ubiquitous human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity and clastogenicity of UV light in mammalian cells. Arsenite may exert its co-genotoxic effects by inhibiting DNA repair. Results from alkaline sucrose gradient sedimentation show that arsenite did not accumulate UV-induced DNA strand breaks in Chinese hamster ovary (CHO) K1 cells as aphidicolin plus hydroxyurea (HU) did. These data indicate that arsenite did not inhibit the activity of DNA polymerase alpha in UV repair. Treatment with arsenite before UV irradiation slightly reduced the DNA strand breaks accumulated by cytosine beta-D-arabinofuranoside (AraC) plus HU. This effect implies that arsenite only slightly inhibited the incision of UV-induced DNA adducts. The low molecular weight DNA accumulated by post-UV incubation with AraC plus HU shifted to high molecular weight upon the incubation of cells in drug-free medium, but this shifting was prohibited by the presence of arsenite. This suggests that arsenite inhibited the rejoining of DNA strand breaks. When a pulse-chase labelling procedure was applied on UV-irradiated cells, the chain elongation of nascent DNA was strongly inhibited by post-incubation with arsenite. These data show that arsenite inhibited post-replication repair in UV-irradiated cells. Therefore, the steps inhibited by arsenite in UV-induced DNA repair in CHO K1 cells are different from human fibroblasts in which the inhibition of excision of pyrimidine dimers by arsenite was reported to be the major target.",
Arsenic,1015896,"Chronic low-level arsenite exposure through drinking water increases blood pressure and promotes concentric left ventricular hypertrophy in female mice Abstract: Cardiovascular disease is the leading cause of death in the United States and worldwide. High incidence of cardiovascular diseases has been linked to populations with elevated arsenic content in their drinking water. Although this correlation has been established in many epidemiological studies, a lack of experimental models to study mechanisms of arsenic-related cardiovascular pathogenesis has limited our understanding of how arsenic exposure predisposes for development of hypertension and increased cardiovascular mortality. Our studies show that mice chronically exposed to drinking water containing 100 parts per billion (ppb) sodium arsenite for 22 weeks show an increase in both systolic and diastolic blood pressure. Echocardiographic analyses as well as histological assessment show concentric left ventricular hypertrophy, a primary cardiac manifestation of chronic hypertension. Live imaging by echocardiography shows a 43% increase in left ventricular mass in arsenic-treated animals. Relative wall thickness (RWT) was calculated showing that all the arsenic-exposed animals show an RWT greater than 0.45, indicating concentric hypertrophy. Importantly, left ventricular hypertrophy, although often associated with chronic hypertension, is an independent risk factor for cardiovascular-related mortalities. These results suggest that chronic low-level arsenite exposure promotes the development of hypertension and the comorbidity of concentric hypertrophy.",
Arsenic,1326975,"SV40-immortalized human keratinocytes as an in vitro model system for studying environmental carcinogens Abstract: BIOSIS COPYRIGHT: BIOL ABS. We have extensively characterized the properties of an in vitro model system of human epidermal keratinocytes immortalized by the oncogenic virus, SV40. Here we show how the unique features of this system can be employed as a tool for studying the effects of both mutagenic and nongenotoxic carcinogens on human epithelial cells. 1. SV40-infected human keratinocyte lines at low serial passage have been used as an in vitro system to study the effects of arsenic. Arsenic as both arsenate and arsenit tantly, analyses of cell cycle kinetics by fluorescence activated cell sorting (FACS) revealed thatthe stimulation of cell growth might be accounted for by a relative shortening of the G1 phase of the cell cycle. 2. The mutagenic effects of the methylating carcinogen, MNNG have been studied using the integrated viral origin of replication in a line of SV40-immortalized human keratinocytes as a target. Sequence data from this system revealed an unusual spectrum of base alterations as compared wit",
Arsenic,1028814,"Human urinary arsenic excretion after one-time ingestion of seaweed, crab, and shrimp Abstract: We studied chemical speciation of arsenic compounds in urine samples by using HPLC with inductively coupled plasma mass spectrometry detection. We examined urinary arsenic excretion patterns and the arsenic species excreted from nine human subjects who ingested seaweed products and crab (or shrimp). Fast urinary excretion of unchanged arsenobetaine was seen after ingestion of crab and shrimp, which contain arsenobetaine as the major arsenic species. In contrast, the arsenosugars, which comprise the major arsenic species in seaweed, are metabolized and have a longer retention time in the human body. When nine volunteers ingested the commercial seaweed product nori, both the urinary arsenic excretion pattern and the excreted arsenic species varied from individual to individual, and as many as six metabolites could be detected. It seems that arsenosugars are not decomposed by stomach acid and that reactions involving enzymatic and (or) microbial activity in the human body may be responsible for the metabolism of arsenosugars.",
Arsenic,1350256,"Distribution of Fe, Zn, Pb, Cu, Cd and As from mining wastes and wastewater along a transect of Taxco river in Guerrero, Mexico Abstract: Inadequate waste disposal from ore processing is one of the main inputs of metals to rivers where they are transported either in dissolved or in particulate form. Heavy metals 'and arsenic from metal-rich wastes may reach hazardous levels to humans and ecosystems, and constitute a negative influence on sustainable development. The present study focuses on determining the concentrations and speciation of dissolved and suspended particulate arsenic, cadmium, copper; lead, zinc and iron produced by the combined input of mine wastes and urban wastewater in the Taxco River. Water samples were collected along the river in both, dry and rainy seasons. Results showed near neutral or slightly basic pH values at most sites, dominated by bicarbonate, sulfate, calcium, sodium and magnesium as the main ions. The highest content of metals measured in the water at site TX3 close to tailings were: Fe and As, mainly in particulate form (54.5 mg/L and 0.047 mg/L respectively), Zn, Pb, Cu and Cd in dissolved form (245.83, 0.217, 3.94 and 1.73 mg/L respectively). Closeness of TX3 to mine tailings allows dragging of material by water and wind induced erosion. This process supplies metals, ions and acid drainage to the river water altering its composition mainly in the dry season (pH 2.8). A seasonal dilution factor was observed in the chemistry of the river; since in the dry season average flow of the studied transect was only 0.05 m(3)/s and in the rainy season the flow increased to 1.45 m(3)/s. Aqueous metal speciation, predicted using WATEQ4F software, reflected the influence of local geology with presence of limestones, as well as sulfide oxidation of minerals within tailings. Speciation results data indicated that oxides, ohyhydroxides and carbonates are the main compounds controlling mobilization/immobilization processes of the studied metals. Metal concentrations over drinking water standards, as well as urban wastewater influence render the river water unsuitable for irrigation and as a drinking water source without a previous treatment, mainly at sites close to discharges and wastes. Environmental protection of the river implies avoiding direct wastewater discharges, as well as particle dragging and acid mine drainage input to the river that may be attained through the construction of physical barriers and water treatment systems.",
Arsenic,2149326,Best Practice Guides on Metals and Related Substances in Drinking Water Arsenic removal processes Abstract: ,
Arsenic,1343443,"Outpatient therapy of canine dirofilariosis according to the heartworm protocol of the American Heartworm Society: Two case studies Abstract: Two dogs imported from Spain with a positive Dirofilariose- antigen test were presented. Both dogs showed a dry cough under exertion. Thoracal x-rays revealed abnormal patterns in the caudal lobe of the lung area. Both dogs were treated according to the Heartworm-Protocol of the American Heartworm Society, but were not hospitalised. For elimination of the microfilariaes Milbemycin-Oxim, Praziquantel (Milbemax®, Novartis, G) was used. Adulticidal therapy was done with the arsenic drug Melarsomine (Immiticide ®, Merial, F) in two steps. The second dose of Melarsomine was administered at least four weeks later. The adulticidal was given two times with 24 hours interval between each treatment. Tetracycline (doxycycline) was used at different time intervals. One dog was treated initially with doxycline (Ronaxan, Merial, D) for 14 days. 16 weeks after adulticidal therapy a heartworm-antigen test was negative. The second dog reveiced doxycycline (Ronaxan®, Merial, D) was given from the first up to the 78th day of treatment. Heartworms were also combated by killing their endosymbionts, wolbachia, by doxycycline. The heartworm antigen test was still negative six weeks after adulticidal therapy.",
Arsenic,1337621,"Enhanced carcinogenicity by coexposure to arsenic and iron and a novel remediation system for the elements in well drinking water Abstract: Various carcinomas including skin cancer are explosively increasing in arsenicosis patients who drink arsenic-polluted well water, especially in Bangladesh. Although well drinking water in the cancer-prone areas contains various elements, very little is known about the effects of elements except arsenic on carcinogenicity. In order to clarify the carcinogenic effects of coexposure to arsenic and iron, anchorage-independent growth and invasion in human untransformed HaCaT and transformed A431 keratinocytes were examined. Since the mean ratio of arsenic and iron in well water was 1:10 in cancer-prone areas of Bangladesh, effects of 1 ?M arsenic and 10 ?M iron were investigated. Iron synergistically promoted arsenic-mediated anchorage-independent growth in untransformed and transformed keratinocytes. Iron additionally increased invasion in both types of keratinocytes. Activities of c-SRC and ERK that regulate anchorage-independent growth and invasion were synergistically enhanced in both types of keratinocytes. Our results suggest that iron promotes arsenic-mediated transformation of untransformed keratinocytes and progression of transformed keratinocytes. We then developed a low-cost and high-performance adsorbent composed of a hydrotalcite-like compound for arsenic and iron. The adsorbent rapidly reduced concentrations of both elements from well drinking water in cancer-prone areas of Bangladesh to levels less than those in WHO health-based guidelines for drinking water. Thus, we not only demonstrated for the first time increased carcinogenicity by coexposure to arsenic and iron but also proposed a novel remediation system for well drinking water.",
Arsenic,2278658,"Arsenic uptake and translocation by plants in pot and field experiments Abstract: A work undertaken by pot and field experiments to assess the suitability of poplars and ferns for the in-situ, phytoextraction, of a dumping site with residues from the roasting process of arseno-pyrite is reported. The main characteristic of this site is the high content of both the As metalloid and heavy metals (e.g., Al, Fe, Cu, Co, Cr, Pb). Two poplar clones (Populus deltoides ‘Dvina’ and Populus x canadensis ‘Orion’) and Pteris vittata (Chinese brake fern) were planted in the contaminated soil both ex situ in pots and in situ. Plant survival, As accumulation in plant tissues, leaf content of pigments, soluble proteins, activity of catalase and SH-groups in both roots and leaves were evaluated during a 24-month study period. Both poplar and fern plants exhibited an increase in the activity of catalase and SH group contents when grown in the presence of pyrite ashes. The results showed that the co-planting system (arsenic-hyperaccumulator fern Pteris vittata and Populus clones) was suitable for phytoextraction of multi-contaminated dumping sites. Agronomic measures such as irrigation, soil tillage and amendments also seem to be necessary for the successful establishment of poplar trees and ferns in contaminated soils in order to enhance plant growth through the improvement of soil conditions.",
Arsenic,1357716,"An Interlaboratory Comparison Programme for Several Toxic Substances in Blood and Urine Abstract: The results were presented of an interlaboratory comparison program established to examine the performance of various laboratories in analyzing blood lead (7439921), urine mercury (7439976), urine arsenic (7440382), urine fluoride (16984488), blood and urine cadmium (7440439), urine chromium (7440473), and serum aluminum (7429905) in workers exposed to these agents. The level of proficiency demonstrated by the participating laboratories was in general adequate for the large scale monitoring of exposed workers. No systematic chronological trend was noted among substances which had been part of the investigative study for over 6 years. This included blood lead and urine analyses for fluoride, arsenic, and mercury. There were marked improvements noted in the accuracy of analyses in the recently introduced blood and urine cadmium studies. The use of different methods resulted in systematic differences in the results only in the case of blood lead determinations. Participating labs using anodic stripping voltammetry obtained results which consistently underestimated the concentrations of lead, particularly at low exposure levels. Of the three atomic absorption methods used, the Delves cup and APDC extraction methods yielded results which were slightly elevated, particularly at low concentrations, while no bias was demonstrated for the graphite furnace atomic absorption method, which became the preferred method.",
Arsenic,2347753,"Biogeochemical Process-Based Design and Performance of a Pilot-Scale Constructed Wetland for Arsenic Removal from Simulated Bangladesh Groundwater Abstract: A pilot-scale constructed wetland treatment system (CWTS) was designed and built to produce bio-geochemical conditions promoting processes targeted for removal of arsenic from simulated Bangladesh ground-water. Two CWTS series were designed to promote coprecipitation and sorption of arsenic with iron oxyhydroxides under oxidizing conditions, and two series were designed to promote precipitation of arsenic sulfide and coprecipitation of arsenic with iron sulfide under reducing conditions. Arsenic removal performance was greater in series with oxidizing conditions than in series with reducing conditions (mean outflow concentrations of 64 and 108 mu g L-1, respectively). Additions of zero-valent iron (ZVI) to oxidizing series and to reducing series enhanced arsenic removal (mean removal efficiencies of 72 and 42%, respectively) compared to unamended series (27 and 20 %, respectively). Arsenic removal performance was significantly greater (alpha=0.05) in the oxidizing series amended with ZVI than in the other series, with removal extents, efficiencies, and rate coefficients ranging from 6 to 79 mu g L-1, 40 to 95 %, and 0.13 to 0.77 day(-1), respectively. Results from this pilot-scale study demonstrate that a CWTS can decrease concentrations of arsenic in arsenic-contaminated water to below the World Health Organization (WHO) drinking water quality guideline of 10 mu g L-1.",
Arsenic,627255,"Phenotypic anchoring of arsenic and cadmium toxicity in three hepatic-related cell systems reveals compound- and cell-specific selective up-regulation of stress protein expression: implications for fingerprint profiling of cytotoxicity Abstract: Exposure of cells to toxic chemicals is known to up-regulate the expression of a number of stress proteins (SPs), including metallothionein (MT) and members of the heat shock protein (HSP) family, and this response may allow the development of a fingerprint profile to identify mechanisms of toxicity in an in vitro toxicology setting. To test this hypothesis, three hepatic-derived cell culture systems (rat hepatoma FGC4 cell line, rat hepatocytes, human hepatoma HepG2 cell line) were exposed to cadmium (as CdCl2) and arsenic (as NaAsO2), two compounds believed to exert their toxicity through an oxidative stress mechanism, under conditions of phenotypic anchoring defined as minimal and mild toxicity (approximately 5 and 25% reduction in neutral red uptake, respectively). The expression of six SPs--MT, HSP25/27, HSP40, HSP60, HSP70, and HSP90--was then determined by ELISA. Expression of four of these SPs--MT, HSP25/27, HSP40 and HSP70--was up-regulated in at least one experimental condition. However, the patterns of expression of these four SPs varied across the experimental conditions, according to differences in toxicant concentration and/or level of toxicity, cell-type and toxicant itself. This lack of uniformity in response of a focussed set of mechanistically defensible targets suggests that similar problems may emerge when using more global approaches based on genomics and proteomics, in which problems of redundancy in targets and uncertain mechanistic relevance will be greater.",
Arsenic,627600,"Non-cancer effects of chronic arsenicosis in Bangladesh: Preliminary results Abstract: A total of 136 patients were studied in three Upazillas of Laxmipur, Barisal and Madaripur districts were selected for health awareness campaign program. According to the existing data, these villages were ranked as high exposure. Demographic data of the patients investigated are showing pigmentation was seen in all—136 cases, keratosis was found only in 110 cases, and skin ulcer was detected in 13 cases. The predominant features are indicating respiratory sign and symptoms followed by conjunctival congestion and redness of eyes. Weakness was predominant symptom, and all most all cases reported weakness. There were few smokers (n = 16) and analyses were confined to non-smokers (n = 94). A total of the 94 subjects participated in this study. The sex ratio was 1:1.3 (male vs. female). The relative risk of chronic cough increased with age (RR = 2.12, for 26-50 age group; RR = 2.30 for age group more than 51) reflecting chronic exposure, but the 95% confidence intervals included unity. The relative risk of chronic bronchitis increased with age (RR = 2.68, for 26-50 age group; RR = 2.30 for age group more than 51) reflecting chronic exposure, but the 95% confidence intervals also included unity. The findings presented here provide evidence that ingestion of inorganic arsenic in drinking water may results in increases risk of chronic cough and bronchitis.",
Arsenic,1016101,"Pre-cancerous changes in urothelial endocytic vesicle leakage, fatty acid composition, and As and associated element concentrations after arsenic exposure Abstract: The urothelium covering the luminal surface of the urinary bladder has developed an efficient permeability barrier that protects it against the back-flow of toxins eliminated in the urine. The subapical endocytic vesicles containing the urinary bladder fluid phase are formed during the micturition cycle by endocytosis processes of the superficial cells. In normal conditions, the permeability barrier of the endocytic vesicles blocks the passage of the fluid phase to the cellular cytoplasm and the fluid is recycled to the bladder lumen. The aim of this work was to investigate the alteration of the endocytic vesicle membrane permeability barrier to toxins such as iAs (inorganic arsenic) administered in drinking water. By using an induced endocytosis model and the fluorescence requenching technique, it is shown that the exposure of rats to ingestion of water containing iAs not only induced pre-cancerous morphological changes, but allowed the differential leakage of an endocytosed fluorescent marker, HPTS, and its quencher, DPX, (hydroxypyrene-1,3,6-trisulfonic acid and p-xylene-bis-pyridinium bromide, respectively) out of the vesicular lumen. The leakage of the cationic DPX was almost complete, while the release of the anionic HPTS molecule was partial and higher in arsenic-treated-rats than in controls. Such membrane alteration would allow the toxins to elude the permeability barrier and to leak out of the endocytic vesicles, thus establishing a &quot;bypass&quot; to the permeability barrier. The retention of As in the urinary bladder, assessed by synchrotron radiation X-ray fluorescence spectrometry (SR-?XRF), was lower than the kidney accumulation of arsenic previously observed by our group and was accompanied by altered concentrations of K, Ca, Fe, Cu and Zn, all ions related to cellular metabolism. The results support the hypothesis that low amounts of endocytosed As can accumulate in the interior of the urothelial superficial cells and initiate the cytotoxic effects reflected in the morphological alterations observed.",
Arsenic,627036,"Arsenite-induced aryl hydrocarbon receptor nuclear translocation results in additive induction of phase I genes and synergistic induction of phase II genes Abstract: Complex mixtures of carcinogenic metalloids, such as arsenic, and polycyclic aromatic hydrocarbons or halogenated aromatic hydrocarbons are common environmental contaminants. The biological consequences of exposure to these mixtures are unpredictable and, although the health effects of individual chemicals may be known, the toxicity of environmental mixtures is largely unexplored. Arsenic, not a potent mutagen by itself, is co-mutagenic with many DNA-damaging agents. Mixtures of arsenite plus benzo[a]pyrene (B[a]P) augment B[a]P mutagenicity, suggesting that arsenite might uncouple expression of phase I and II genes responsible for detoxification. We have studied the effects of arsenite exposure on the activation of the aryl hydrocarbon receptor (AHR) and its subsequent role in gene transactivation. Treatment of mouse Hepa-1 cells with arsenite induces AHR nuclear translocation and binding to the Cyp1a1 gene promoter with the same efficiency as tetrachlorodibenzo-p-dioxin (TCDD), the most potent ligand of the AHR; however, TCDD and B[a]P are an order of magnitude more potent than arsenite in up-regulating Cyp1a1 transcription. Global profiling analyses of cells treated with arsenite plus B[a]P indicate that several phase I and II detoxification genes are in some cases additively and in others synergistically deregulated by the mixtures. Real-time reverse transcription-polymerase chain reaction analyses of mouse embryonic fibroblasts showed that the mixtures had an additive effect on the mRNA levels of Cyp1b1, a prototypical phase I detoxification gene, and an AHR-dependent synergistic effect on the corresponding levels of Nqo1, a prototypical phase II gene. We conclude that exposure to arsenite/B[a]P mixtures causes regulatory changes in the expression of detoxification genes that ultimately affect the metabolic activation and disposition of toxicants.",
Arsenic,1354189,"Heavy metal concentrations in raw milk collected from different regions of Samsun, Turkey Abstract: ",
Arsenic,628329,"The role of active arsenic species produced by metabolic reduction of dimethylarsinic acid in genotoxicity and tumorigenesis Abstract: In recent research of arsenic carcinogenesis, many researchers have directed their attention to methylated metabolites of inorganic arsenics. Because of its high cytotoxicity and genotoxicity, trivalent dimethylated arsenic, which can be produced by the metabolic reduction of dimethylarsinic acid (DMA), has attracted considerable attention from the standpoint of arsenic carcinogenesis. In the present paper, we examined trivalent dimethylated arsenic and its further metabolites for their chemical properties and biological behavior such as genotoxicity and tumorigenicity. Our in vitro and in vivo experiments suggested that the formation of cis-thymine glycol in DNA was induced via the production of dimethylated arsenic peroxide by the reaction of trivalent dimethylated arsenic with molecular oxygen, but not via the production of common reactive oxygen species (ROS; superoxide, hydrogen peroxide, hydroxyl radical, etc.). Thus, dimethylated arsenic peroxide may be the main species responsible for the tumor promotion in skin tumorigenesis induced by exposure to DMA. Free radical species, such as dimethylarsenic radical [(CH(3))(2)As.] and dimethylarsenic peroxy radical [(CH(3))(2)AsOO.], that are produced by the reaction of molecular oxygen and dimethylarsine [(CH(3))(2)AsH], which is probably a further reductive metabolite of trivalent dimethylated arsenic, may be main agents for initiation in mouse lung tumorigenesis.",
Arsenic,1797743,"Method for Speciation of Organoarsenic in Mussels by Liquid Chromatography Coupled to Electrospray Ionization and QTRAP Tandem Mass Spectrometry Abstract: Arsenic toxicity to humans critically depends on the chemical form of the arsenic. The Expert Committee of the Food and Agriculture Organization and the World Health Organization defined a tolerable intake only for inorganic arsenic, although the toxicity of some organoarsenic compounds is known. Arsenobetaine (AsB), arsenocholine (AsC), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) are abundant in shellfish. We present a fast and reliable method for identification of the type of organic arsenic in mussels by using liquid chromatography coupled to electrospray ionization tandem mass spectrometry on triple quadrupole with parallel determination of total arsenic by atomic absorption spectrophotometry. The method was validated by evaluating mean recoveries, repeatability, specificity, limits of quantification, and limits of detection that produced satisfactory results. The method was used to carry out the first survey of the concentrations of AsB, AsC, MMA, and DMA in seafood from southern Italy. Total As concentrations ranged from 1.38 to 12.79 mg/kg. AsB and DMA were detected in all samples (AsB: 0.72 to 10.36 mg/kg; DMA: 0.28 to 1.08 mg/kg), and concentrations of AsC and MMA ranged from 0.20 to 1.53 mg/kg. This method allowed us to rapidly and inexpensively identify arsenic types in fishery products and would be suitable for routine detection of organoarsenic compounds in molluscs.",
Arsenic,1519187,Studies on surface characterisation and isotherm modelling: Biosorption of arsenic(III) onto low cost biosorbent derived from orange peel Abstract: ,
Arsenic,1351752,"Study on metal-triggered callose deposition in roots of maize and soybean Abstract: Callose plays important roles in a variety of processes of plant development, and/or in a response to a range of biotic and abiotic stresses. In the current work we have studied and compared the effect of lead, cadmium and arsenic on accumulation of newly formed callose deposits in the roots of maize and soybean. We observed formation of characteristic callose deposits in the root cell walls, probably associated with plasmodesmata, depending on the type of metal and the plant species investigated. Further, the callose turnover was analysed by measuring of total callose content as well as activities of total ?-(1,3)-glucanases in roots. The latter enzymes are responsible for callose depletion, and their possible role during metal stress has previously been proposed. However, neither of these biochemical values appeared to be sufficiently reliable for scoring the altered callose turnover (including local deposits) in plant tissue. The microscopical observations are discussed in light of the biochemical data obtained.",
Arsenic,627126,"Arsenic-induced oxidative stress and its reversibility following combined administration of N-acetylcysteine and meso 2,3-dimercaptosuccinic acid in rats Abstract: 1. The present study examined whether arsenic induces oxidative stress in liver, brain and erythrocytes (RBC) based on the investigation of certain selected parameters. It also explored the possibility that combined administration of N-acetylcysteine (NAC) and meso 2,3-dimercaptosuccinic acid (DMSA) was capable of achieving better reversibility in the parameters indicative of arsenic-induced oxidative stress than individual treatment with either of these drugs. 2. Male rats were exposed to 100 p.p.m. sodium arsenite in their drinking water for 12 weeks (equivalent to 12 mg/kg As). The arsenic was then removed and rats were given NAC (1 mmol/kg per day), DMSA (1 mmol/kg per day) or a combination of the two, orally, once daily for 5 days. Animals not given arsenic and those given arsenic but not NAC or DMSA served as negative and positive controls, respectively. 3. Twelve weeks of arsenic exposure was found to deplete glutathione (GSH) levels, increase oxidized glutathione (GSSG) and promote malondialdehyde (MDA) production in both liver and brain samples. In addition to a significant reduction in RBC delta-aminolevulinic acid dehydratase (ALAD) activity and GSH levels, a marked elevation in MDA production may also contribute to arsenic-induced oxidative stress. 4. Treatment with either NAC or DMSA alone partially reversed arsenic-induced alterations in hepatic GSH and MDA, while only brain MDA levels responded favourably to these drugs. Only DMSA appeared to restore blood ALAD, while RBC MDA levels responded favourably to both drugs. Treatment with DMSA also produced an effective depletion of blood and hepatic arsenic concentrations. In the liver, most of these parameters were more effectively reversed by combined treatment with NAC and DMSA compared with the effects of either drug alone. 5. These results provide in vivo evidence of arsenic-induced oxidative stress in liver, brain and RBC and indicate that these effects can be mitigated by pharmacological intervention that encompasses combined treatment with NAC and DMSA.",
Arsenic,2298738,"Arsenite binding to sulfhydryl groups in the absence and presence of ferrihydrite: a model study Abstract: Binding of arsenite (As(III)) to sulfhydryl groups (Sorg(-II)) plays a key role in As detoxification mechanisms of plants and microorganisms, As remediation techniques, and reduced environmental systems rich in natural organic matter. Here, we studied the formation of Sorg(-II)-As(III) complexes on a sulfhydryl model adsorbent (Ambersep GT74 resin) in the absence and presence of ferrihydrite as a competing mineral adsorbent under reducing conditions and tested their stability against oxidation in air. Adsorption of As(III) onto the resin was studied in the pH range 4.0-9.0. On the basis of As X-ray absorption spectroscopy (XAS) results, a surface complexation model describing the pH dependence of As(III) binding to the organic adsorbent was developed. Stability constants (log K) determined for dithio ((AmbS)2AsO(-)) and trithio ((AmbS)3As) surface complexes were 8.4 and 7.3, respectively. The ability of sulfhydryl ligands to compete with ferrihydrite for As(III) was tested in various anoxic mixtures of both adsorbents at pH 7.0. At a 1:1 ratio of their reactive binding sites, R-SH and ?FeOH, both adsorbents possessed nearly identical affinities for As(III). The oxidation of Sorg(-II)-As(III) complexes in water vapor saturated air over 80 days, monitored by As and S XAS, revealed that the complexed As(III) is stabilized against oxidation (t1/2 = 318 days). Our results thus document that sulfhydryl ligands are highly competitive As(III) complexing agents that can stabilize As in its reduced oxidation state even under prolonged oxidizing conditions. These findings are particularly relevant for organic S-rich semiterrestrial environments subject to periodic redox potential changes such as peatlands, marshes, and estuaries.",
Arsenic,1357355,"Cancer Incidence and Mortality among Swedish Leather Tanners Abstract: The incidence of cancer and mortality among Swedish leather tanners was investigated. The cohort consisted of 2,026 workers from three tanneries who had been exposed to chromium (7440473) compounds, arsenic (7440382), mercury (7439976) compounds including methylmercury (22967926), azo dyes, benzidine (92875), and various organic solvents. Information on causes of death and tumors were obtained from Statistics Sweden, and the National Swedish Tumor Registry. Risk estimates were calculated for the period 1952 to 1989, and cause specific standardized mortality ratios (SMRs) and standardized incidence ratios (SIRs) were calculated. Results showed that overall mortality did not differ from the expected, and was true for both malignant tumors and cardiovascular disease. The overall incidence of cancer was slightly but significantly enhanced (1.16). When a 20 year (yr) latency period was excluded the estimates increased to 1.22. Risk estimates were multiple myeloma SIR 2.54, soft tissue sarcoma SIR 4.27, breast cancer SIR 1.47, prostate cancer SIR 1.31, pancreatic cancer SIR 1.55, lung cancer SIR 1.33, bladder cancer SIR 1.25, and lip cancer SIR 2.45. When a 20yr induction period was introduced, the risk estimates increased slightly. The overall incidence of cancer was unaffected by the introduction of the 20yr latency period in facility-A and facility-B, but did significantly increase in facility-C due to soft tissue sarcoma, and lip and prostate cancers. Workers employed for at least 10yr had a higher overall incidence of cancer (SIR 1.31). A tentative association between employment duration and prostate cancer risk was evident, but not for lung cancer. No obvious associations were evident between soft tissue sarcoma and myelomas. The authors conclude that there is a risk of soft tissue sarcoma, and an excess (although statistically not significant) of multiple myelomas in Swedish leather tanners.",
Arsenic,1019445,"Lack of promotional effects of groundwater contaminant mixtures on the induction of preneoplastic foci in rat liver Abstract: F344 rats were exposed to drinking water mixtures of seven of the most common groundwater contaminants associated with hazardous waste sites [arsenic, benzene, chloroform, chromium, lead, phenol, and trichloroethylene (TCE)] as the full mixture or submixtures of the organic and/or inorganic chemicals. The lowest concentrations (1x) of the individual chemicals were environmentally realistic and below what would be expected to induce significant short-term toxicity. This study was intended to determine if previously reported increases in localized hepatocellular proliferation in response to these chemicals might be correlated with increased risk for hepatocarcinogenesis. Rats were exposed via a drinking water solution to the full seven- chemical mixture (at 1x and 10x concentrations), submixtures of the organic or inorganic chemicals (at 10x concentrations), a mixture of TCE, lead, and chloroform (TLC submixture at 10x and 100x concentrations), or deionized water as a control. The rats were evaluated for promotion of placental glutathione-S-transferase (GST-P) positive preneoplastic liver cell foci after diethylnitrosamine (DEN) initiation and partial hepatectomy. Focus formation, cell proliferation, and apoptosis were evaluated after exposure to DEN or saline controls, the chemical mixtures or deionized water controls, or combinations of these treatments. The total number and area of GST-P positive foci in DEN-treated rats exposed to the full seven-chemical mixture was increased as compared with the DEN-water controls, but this was statistically significant only for total focus area in the 1x dose group. In DEN-treated rats, the inorganic or TLC submixtures resulted in a significant reduction in number and area of GST-P positive foci. Focus area also was decreased in the organic submixture-treated group, but not significantly. Hepatocellular proliferation was not significantly changed in the chemical mixture saline groups as compared with the mixture water controls. After DEN treatment, however, cell proliferation was significantly decreased after the 10x seven-chemical and organic mixture treatments and the 100x TLC mixture treatment. Different groups showed either increased or decreased apoptotic rates which did not correlate well with proliferation rates or focus formation. Mixtures of these seven chemicals, therefore, did not appear to act as promoters of hepatic foci at environmentally relevant concentrations, and some mixture combinations appeared to decrease promotional activity.",
Arsenic,1339192,"Effect of Pleurotus florida lectin (PFL) on arsenic induced activities of splenoctyes in rodents Abstract: The present study was undertaken to investigate the protective effect of Pleurotus florida lectin (PFL) against arsenic-induced cytotoxicity and oxidative damages in freshly isolated splenocytes of rodents. Our finding indicated that arsenic caused reduction in cell adhesion, morphological alterations, cell proliferation, nitro blue tetrazolium (NBT) index, superoxide dismutase (SOD) activity, catalase (CAT) activity and relative mRNA expression of SOD2 in relation to housekeeping gene glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and increased production of nitric oxide (NO), protein carbonyl (PC) and lipid peroxidation levels (LPO) assembled to play key factors for cytotoxicity and oxidative stress. PFL normalized cellular damages and enhanced SOD production pathway relating to gene expression. Further studies are needed to address effective phytochemicals of the edible mushroom and their mechanism.",
Arsenic,1797759,"Bound states, electron localization and spin correlations in low-dimensional GaAs/AlGaAs quantum constrictions Abstract: We analyze the occurrence of local magnetization and the effects of electron localization in different models of quantum point contacts (QPCs) using spin-relaxed density functional theory (DFT/LSDA) by means of numerical simulations. In the case of soft confinement potentials the degree of localization is weak and we therefore observe only traces of partial electron localization in the middle of the QPC. In the pinch-off regime there is, however, distinct accumulation at the QPC edges. At the other end, strong confinement potential, low-electron density in the leads and top or implant gates favor electron localization. In such cases one may create a variety of electron configurations from a single localized electron to more complex structures with multiple rows and Wigner lattices.",
Arsenic,1597318,"Arsenic transport in irrigation water across rice-field soils in Bangladesh Abstract: Experiments were conducted to analyze processes impacting arsenic transport in irrigation water flowing over bare rice-field soils in Bangladesh. Dissolved concentrations of As, Fe, P, and Si varied over space and time, according to whether irrigation water was flowing or static. Initially, under flowing conditions, arsenic concentrations in irrigation water were below well-water levels and showed little spatial variability across fields. As flowing-water levels rose, arsenic concentrations were elevated at field inlets and decreased with distance across fields, but under subsequent static conditions, concentrations dropped and were less variable. Laboratory experiments revealed that over half of the initial well-water arsenic was removed from solution by oxidative interaction with other water-column components. Introduction of small quantities of soil further decreased arsenic concentrations in solution. At higher soil-solution ratios, however, soil contributed arsenic to solution via abiotic and biotic desorption. Collectively, these results suggest careful design is required for land-based arsenic-removal schemes.",
Arsenic,2279329,"Compact portable biosensor for arsenic detection in aqueous samples with Escherichia coli bioreporter cells Abstract: We present a compact portable biosensor to measure arsenic As(III) concentrations in water using Escherichia coli bioreporter cells. Escherichia coli expresses green fluorescent protein in a linearly dependent manner as a function of the arsenic concentration (between 0 and 100??g/L). The device accommodates a small polydimethylsiloxane microfluidic chip that holds the agarose-encapsulated bacteria, and a complete optical illumination/collection/detection system for automated quantitative fluorescence measurements. The device is capable of sampling water autonomously, controlling the whole measurement, storing and transmitting data over GSM networks. We demonstrate highly reproducible measurements of arsenic in drinking water at 10 and 50??g/L within 100 and 80 min, respectively.",
Arsenic,710891,"Coenzyme Q10 counteracts testicular injury induced by sodium arsenite in rats Abstract: The protective effect of coenzyme Q10 against testicular toxicity induced by sodium arsenite (10mg/kg/day, orally for two consecutive days) was investigated in rats. Coenzyme Q10 treatment (10mg/kg/day, i.p.) was applied for five consecutive days, starting three days before arsenite administration. Coenzyme Q10 significantly increased serum testosterone level which was reduced by sodium arsenite. Coenzyme Q10 significantly suppressed lipid peroxidation, restored the depleted antioxidant defenses, and attenuated the increases of tumor necrosis factor-? and nitric oxide resulted from arsenic administration. Also, the elevation of arsenic ion, and the reductions of selenium and zinc ions in testicular tissue were mitigated by coenzyme Q10. Histopathological examination showed that testicular injury mediated by arsenic was ameliorated by coenzyme Q10 treatment. Immunohistochemical analysis revealed that coenzyme Q10 significantly decreased the arsenic-induced expression of inducible nitric oxide synthase, nuclear factor-?B, Fas ligand and caspase-3 in testicular tissue. It was concluded that coenzyme Q10 represents a potential therapeutic option to protect the testicular tissue from the detrimental effects of arsenic intoxication.",
Arsenic,1936056,"The metabolic acclimation of Arabidopsis thaliana to arsenate is sensitized by the loss of mitochondrial lipoamide dehydrogenase2, a key enzyme in oxidative metabolism Abstract: Mitochondrial lipoamide dehydrogenase is essential for the activity of four mitochondrial enzyme complexes central to oxidative metabolism. The reduction in protein amount and enzyme activity caused by disruption of mitochondrial LIPOAMIDE DEHYDROGENASE2 enhanced the arsenic sensitivity of Arabidopsis thaliana. Both arsenate and arsenite inhibited root elongation, decreased seedling size and increased anthocyanin production more profoundly in knockout mutants than in wild-type seedlings. Arsenate also stimulated lateral root formation in the mutants. The activity of lipoamide dehydrogenase in isolated mitochondria was sensitive to arsenite, but not arsenate, indicating that arsenite could be the mediator of the observed phenotypes. Steady-state metabolite abundances were only mildly affected by mutation of mitochondrial LIPOAMIDE DEHYDROGENASE2. In contrast, arsenate induced the remodelling of metabolite pools associated with oxidative metabolism in wild-type seedlings, an effect that was enhanced in the mutant, especially around the enzyme complexes containing mitochondrial lipoamide dehydrogenase. These results indicate that mitochondrial lipoamide dehydrogenase is an important protein for determining the sensitivity of oxidative metabolism to arsenate in Arabidopsis.",
Arsenic,1508539,"Na(3)Al(AsO(4))(2) Abstract: The structure of the title compound tris-odium aluminium bis-(arsenate), Na(3)Al(AsO(4))(2), is built up from AlO(4) and AsO(4) corner-sharing tetra-hedra, forming an undulating two-dimensional framework parallel to (100). The layers are constituted of large Al(6)As(6)O(36) rings made up from six AlO(4) and AsO(4) tetra-hedra in which two sodium cations are situated, the third sodium cation being located in the inter-layer space. The structural relationships between the title compound and Na(3)Fe(PO(4))(2), NaAlCo(PO(4))(2) and Al(5)Co(3)(PO(4))(8) are discussed.",
Arsenic,1326931,"Comparative investigations of the genotoxic effects of metals in the single cell gel (SCG) assay and the sister chromatid exchange (SCE) test Abstract: Sodium arsenite (NaAsO2) and cadmium sulphate (CdSO4) were tested for their ability to induce genotoxic effects in the single cell gel (SCG) assay and the sister chromatid exchange (SCE) test in human blood cultures in vitro. Both metals induced DNA damage in white blood cells that was expressed and detected as DNA migration in the SCG assay. Dose dependent effects were seen for cadmium in concentrations from 5 × 10?4-5 × 10?3 M and for arsenic in concentrations from 2 × 10?4-1.5 × 10?3 M. The distribution of DNA migration among cells, a function of dose, revealed that the majority of exposed cells expressed more DNA damage than cells from control cultures and that with increasing length of DNA migration the variability in migration among cells increased as well. Treatment of cells for 2 hr or 24 hr beginning 48 hr after the start of the blood cultures did not increase the SCE frequency in the case of cadmium but caused a small but significant SCE induction with arsenic at the highest concentration. The metal concentrations which could be investigated in the SCE test were much lower due to a strong toxic effect. Metal concentrations which were toxic in the SCE test were without visible effect in the SCG assay. Thus the two endpoints for the determination of genotoxic effects in vitro differed markedly with respect to the detection of genotoxicity induced by metals. These differences and the biological significance of the findings are discussed.",
Arsenic,1252588,"Sodium arsenite disturbs mitosis and induces chromosome loss in human fibroblasts Abstract: Arsenite, a unique human carcinogen, induces many types of cytogenetic alterations, such as sister chromatid exchanges, chromosome aberrations, and endoreduplication in a variety of in vivo and in vitro systems. Cytogenetic alterations are frequently associated with cancer development. The purpose of this study was to explore how arsenite induces cytogenetic alterations in human skin fibroblasts (HFW). The present results show that treatment of G2-enriched HFW cells with 5 microM arsenite results in significant delay of cell cycle progression, accumulation of mitotic cells, and prolongation of mitosis. Arsenite-induced G2 and mitotic delay are accompanied by accumulation of cyclin B1 and hyperphosphorylation of cdc2 and Mos proteins. In addition to mitotic delay and prolongation, arsenite treatment also induced out-of-phase centromere separation and alterations of chromosome segregation, such as the appearance of c-metaphase, ball-metaphase, and lagged chromosomes. Unlike spindle poisons, arsenite at the dose range used did not inhibit the spindle fiber formation but conceivably deranges the spindle apparatus. By analyzing the karyotype of established subclones surviving arsenite injury, 18% (8 of 44) showed one chromosome loss, whereas all 26 subclones derived from the untreated cultures were diploid. Furthermore, most arsenite-treated clones manifest prolonged life span (86 +/- 18 population doublings) as compared to those derived from the untreated cultures (44 +/- 11 population doublings). Unfortunately, none became immortal. Collectively, treatment of the G2-enriched HFW cells with arsenite can disturb the mitotic events and subsequently induce chromosome loss.",
Arsenic,1360232,"Arsenic in blood and urine of forest workers: As indices of exposure to to cacodylic acid Abstract: HEEP COPYRIGHT: BIOL ABS. Five healthy forest workers exposed to cacodyllic acid (an herbicide) during a 2 mo. period were observed for evidence of accumulation of As in the blood, the pattern of its urinary excretion, and signs of clinical toxicity. Urinary As appeared to constitute an index of exposure, with excretion levels increasing within 1 wk. Blood levels correlated poorly with exposure. Worker education and proper safety precautions in clothing must be emphasized. Arsine gas in treated forest areas may be potentially dangerous to forest workers.",
Arsenic,1327406,"Caveolin-Induced Activation of the Phosphatidylinositol 3-Kinase/Akt Pathway Increases Arsenite Cytotoxicity Abstract: The inhibitory effect of caveolin on the cellular response to growth factor stimulation is well established. Given the significant overlap in signaling pathways involved in regulating cell proliferation and stress responsiveness, we hypothesized that caveolin would also affect a cell's ability to respond to environmental stress. Here we investigated the ability of caveolin-1 to modulate the cellular response to sodium arsenite and thereby alter survival of the human cell lines 293 and HeLa. Cells stably transfected with caveolin-1 were found to be much more sensitive to the toxic effects of sodium arsenite than either untransfected parental cells or parental cells transfected with an empty vector. Unexpectedly, the caveolin-overexpressing cells also exhibited a significant activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which additional studies suggested was likely due to decreased neutral sphingomyelinase activity and ceramide synthesis. In contrast to its extensively documented antiapoptotic influence, the elevated activity of Akt appears to be important in sensitizing caveolin-expressing cells to arsenite-induced toxicity, as both pretreatment of cells with the PI3K inhibitor wortmannin and overexpression of a dominant-negative Akt mutant markedly improved the survival of arsenite-treated cells. This death-promoting influence of the PI3K/Akt pathway in caveolin-overexpressing cells appeared not to be unique to sodium arsenite, as wortmannin pretreatment also resulted in increased survival in the presence of H(2)O(2). In summary, our results indicate that caveolin-induced upregulation of the PI3K/Akt signaling pathway, which appears to be a death signal in the presence of arsenite and H(2)O(2), sensitizes cells to environmental stress.",
Arsenic,1704065,"Species-level study on arsenic availability from dietary components Abstract: Arsenic (As) contaminated water and foodstuffs are of major concern. Samples of drinking–cooking water (n = 50), raw rice (n = 50), common vegetables (eight types), and common pulses (three types) were collected from households in the endemic region. The study found up to 70% As reduction by using safe water for cooking of rice and vegetables. Speciation study reflected more arsenate than arsenite and other organic arsenicals in all the types of samples. Male intake of 293 ?g As through drinking water contained 38 ?g arsenite and 246 ?g arsenate, and female intake of 199 ?g As contained 167 ?g arsenate and 25 ?g arsenite. In cooked rice, 108 ?g As contained 69 ?g arsenate and 17 ?g arsenite with 9 ?g dimethylarsonic acid (DMA). Total As consumption from cooked vegetables was 45 ?g with 34 and 4 ?g of arsenite and arsenate, respectively, and 5 ?g of DMA. Data indicate that cooking with As-free water removes arsenic in already contaminated foodstuffs but without interconversion of the As species, from toxic inorganic to less toxic organic forms.",
Arsenic,627097,"Evaluation of urinary 8-hydroxydeoxyguanine in healthy Japanese people Abstract: The urinary concentration of 8-hydroxydeoxyguanine (8-0HdG), which is a biomarker of oxidative DNA damage, was measured in 248 healthy Japanese, and its correlations with life style, urinary metal elements, serum antioxidants, and other plasma or serum factors were investigated. The mean urinary concentration of 8-0HdG was 15.2±5.71 ng/mg creatinine. Mean urinary 8-0HdG was not signiiicantly different in terms of age «45, ?-45), gender, smoking (no, <20, ?-20), and alcohol consumption (no, occasionally, sometimes and usually). Moreover, multiple regression analysis showed a signi[icant association between urinary 8-0HdG and urinary arsenic (As) or chromium (Cr), and a tendency for association between the former and aluminum (AI) and nickel (Ni). Age, gender and plasma or serum factors including antioxidants, lipid peroxide, HbAlc, BUN, and iron did not show such an association. The present study suggests that natural exposure to toxic metal elements such as As, Cr, and Ni may influence oxidative DNA damage in healthy people under usual environmental management. Therefore, the measurement of urinary metals such as As, Ni and Cr is prerequisite for the study of the relationship between urinary 8-0HdG and other variable factors.",
Arsenic,1015968,"Correlation between arsenic concentration in fish and human scalp hair of people living in arsenic-contaminated and noncontaminated areas of Pakistan Abstract: The effects of arsenic (As) toxicity due to frequent consumption of arsenic-contaminated fish was estimated by the analysis of scalp hair of adult males, living near arsenic-contaminated area of Pakistan. For comparison purposes, scalp hair samples were also collected from the inhabitants of Hyderabad city consuming fish species with low levels of As, collected from Indus River. Concentration of As in scalp hair samples was analyzed by using hydride generation atomic absorption spectrometry (HG AAS), after microwave-assisted acid digestion. The accuracy of the As measurement was tested simultaneously analyzing certified reference material. The concentration of As in muscle tissues of fish species were found in the range of 2.11 to 14.1 ?g/g and 1.92 to 12.2 ?g/g, collected from arsenic-contaminated and noncontaminated areas, respectively. Exposed subjects had significantly elevated levels of As in scalp hair samples (0.72-4.94 ?g/g) as compared with referent subjects (0.21-1.484 ?g/g; p?&lt;?0.01). The As levels in scalp hair was positively correlated with As levels in fish.",
Arsenic,1597440,Arsenic induced clinico-hemato pathological alteration in brouilers and its attenuation by vitamin E and selenium Abstract: ,
Arsenic,1019976,"Fighting arsenic at the grassroots: experience of BRAC's community awareness initiative in Bangladesh Abstract: The study evaluates the arsenic mitigation project of BRAC in raising awareness of arsenic poisoning in rural communities in Bangladesh. Data came from selected project villages in south-western Bangladesh. Comparison villages were also selected from the same region. A total of 1240 randomly selected adults were interviewed in May 2000. Findings reveal that the mitigation project played a significant, positive role in raising awareness of the safe water options, signs of arsenicosis, mode of transmission and the type of treatment. Testing tube-well water for arsenic created curiosity, innovation and interest in the community, and the water treatment plant became a symbol of the arsenic campaign. The study concludes that the behavioural change aspects of the arsenic mitigation project have the potential to significantly improve the level of understanding about arsenic contamination in the traditional communities.",
Arsenic,1031866,"Chronic oral arsenic intoxication as a possible aetiological factor in idiopathic portal hypertension (non-cirrhotic portal fibrosis) in India Abstract: Estimates were made of the arsenic concentration in liver specimens from nine patients having idiopathic portal hypertension (IP), and in four livers these were found to be significantly higher than those in patients with cirrhosis and in control subjects. The splenovenogram revealed extensive portosystemic collateral circulation. Corrected sinusoidal pressure and blood flow studies showed higher levels in four patients than in normal subjects. Microscopic examination of liver tissues revealed periportal fibrosis. The higher hepatic arsenic levels that were found were due to the inadvertent drinking of water contaminated with arsenic, adulterated opium, and indigenous medicines. A history of opium intake was not forthcoming but two patients had drunk water contaminated with arsenic and two others had taken bhasams (Ayurvedic medicines prepared by repeated oxidation of ores). Though the aetiology of idiopathic portal hypertension is not known, it is possible that arsenic intake may be one of the factors.",
Arsenic,1019276,Arsenic uptake in orchard trees: Implications for dendroanalysis Abstract: The distribution of arsenic in the stems of fruit trees grown in soils exposed to arsenical pesticides has been studied using neutron activation analysis. The results show arsenic to be confined mainly to heartwood near the pith and active xylem tissue in the most recent annual growth rings. These results suggest that dendroanalysis for arsenic in fruit trees will not yield a reliable chronology of arsenic exposure.,
Arsenic,2088589,"Analysis of the biological response of mouse liver (Mus musculus) exposed to As2O3 based on integrated -omics approaches Abstract: Organic and inorganic mass spectrometries were used to investigate the biochemical response of mice (Mus musculus) to inorganic arsenic exposure using liver as the target organ. The toxicological effects of trivalent inorganic arsenic after oral administration (3 mg kg(-1) body weight and per day) were investigated over a period of 7 days using metallomics, metabonomics and redox proteomics approaches. Size-exclusion chromatography (SEC) with ICP-MS detection was combined with anion exchange chromatography (AEC) to characterize the biological response of the exposed mice. On the other hand, direct infusion mass spectrometry (DI-ESI-QTOF-MS) of polar and lipophilic extracts using positive and negative modes of acquisition (ESI+/ESI-) provided information about time-dependent changes in endogenous metabolites identified by Partial Least Square-Discriminant Analysis (PLS-DA). Finally, the study has been complemented with the evaluation of up/down-regulation of enzymes related to oxidative stress such as superoxide dismutase (SOD), glutathione reductase (GR), catalase (CAT) and peroxidases in connection with metal toxicity issues. The results show that the inorganic arsenic methylation in the liver may reach the saturation point upon chronic exposure to the element. On the other hand, SEC-ICP-MS coupling provided information about metal containing-proteins and metabolites related to arsenic exposure (metallomics) which has been correlated with the changes in the global metabolism (metabonomics), also considering their consequences on the redox status of protein and protein expression (redox proteomics). Our study shows that arsenic causes biochemical pathway alterations, such as energy metabolism (e.g. glycolysis, Krebs cycle), amino acid metabolism, choline metabolism and degradation of membrane phospholipids (apoptosis). This work illustrates the high reliability of the integrated use of organic mass spectrometry for the metabonomic study of biochemical effects induced by As2O3, with inorganic mass spectrometry for metallomic and speciation assessment of arsenic biomethylation in the liver of exposed mice, and redox proteomics to evaluate inhibition of enzymatic activity in different proteins such as superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) caused by this element. In conclusion, the integration of metallomics, metabolomics and redox proteomics results provides a more comprehensive evaluation about the biological response in experiments dealing with exposure to toxic metals.",
Arsenic,1016264,"Direct data manipulation for local decision analysis as applied to the problem of arsenic in drinking water from tube wells in Bangladesh Abstract: A wide variety of tools are available, both parametric and nonparametric, for analyzing spatial data. However, it is not always clear how to translate statistical inferences into decision recommendations. This article explores the possibilities of estimating the effects of decision options using very direct manipulation of data, bypassing formal statistical analysis. We illustrate with the application that motivated this research, a study of arsenic in drinking water in nearly 5,000 wells in a small area in rural Bangladesh. We estimate the potential benefits of two possible remedial actions: (1) recommendations that people switch to nearby wells with lower arsenic levels; and (2) drilling new community wells. We use simple nonparametric clustering methods and estimate uncertainties using cross-validation.",
Arsenic,627509,"Gene expression profiles in peripheral lymphocytes by arsenic exposure and skin lesion status in a Bangladeshi population Abstract: Millions of individuals worldwide are chronically exposed to arsenic through their drinking water. In this study, the effect of arsenic exposure and arsenical skin lesion status on genome-wide gene expression patterns was evaluated using RNA from peripheral blood lymphocytes of individuals selected from the Health Effects of Arsenic Longitudinal Study. Affymetrix HG-U133A GeneChip (Affymetrix, Santa Clara, CA) arrays were used to measure the expression of approximately 22,000 transcripts. Our primary statistical analysis involved identifying differentially expressed genes between participants with and without arsenical skin lesions based on the significance analysis of microarrays statistic with an a priori defined 1% false discovery rate to minimize false positives. To better characterize differential expression, we also conducted Gene Ontology and pathway comparisons in addition to the gene-specific analyses. Four-hundred sixty-eight genes were differentially expressed between these two groups, from which 312 differentially expressed genes were identified by restricting the analysis to female never-smokers. We also explored possible differential gene expression by arsenic exposure levels among individuals without manifest arsenical skin lesions; however, no differentially expressed genes could be identified from this comparison. Our findings show that microarray-based gene expression analysis is a powerful method to characterize the molecular profile of arsenic exposure and arsenic-induced diseases. Genes identified from this analysis may provide insights into the underlying processes of arsenic-induced disease and represent potential targets for chemoprevention studies to reduce arsenic-induced skin cancer in this population.",
Arsenic,1794815,"Changes during a century in trace element and macronutrient concentrations of an agricultural soil Abstract: Surface soil and subsoil samples collected in 2012 from a long-term agronomic experimental field at Cornell University were digested in concentrated nitric-perchloric acid and analyzed for macronutrient and trace element concentrations by ICP-OES (inductively coupled plasma optical emission spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry). Archived soil samples, taken from the same field nearly a century earlier (1913), were simultaneously analyzed by the same methods to determine any temporal trends in acid-soluble soil elemental composition that might have resulted from agricultural practices and amendments or from diffuse pollution at this semirural site. Modest increases in surface soil concentrations of several macronutrients (P, Ca, Mg, K) were observed between 1913 and 2012, probably attributable to fertilizer and lime amendments. Most trace elements showed either no significant concentration increase (Zn, Ba, Mn) or a small increase (Ni, Cr) in the surface soil. The greatest relative increase in surface soil trace metal concentrations was for arsenic (81%), followed by lead (40%) and cadmium (33%), although acid-soluble concentrations of these toxic metals in 2012 remained in the range considered typical for background levels in uncontaminated agricultural soils of this region. Cadmium measured in acid digests by ICP-OES was shown to overestimate total soil Cd at these low near-background concentrations, with both ICP-MS and a flame atomic absorption method using a preconcentration step for Cd in extracts providing results more consistent with known total soil Cd concentrations of certified standards.",
Arsenic,1015830,"Advances in carcinogenic metal toxicity and potential molecular markers Abstract: Metal compounds such as arsenic, cadmium, chromium, cobalt, lead, mercury, and nickel are classified as carcinogens affecting human health through occupational and environmental exposure. However, the underlying mechanisms involved in tumor formation are not well clarified. Interference of metal homeostasis may result in oxidative stress which represents an imbalance between production of free radicals and the system's ability to readily detoxify reactive intermediates. This event consequently causes DNA damage, lipid peroxidation, protein modification, and possibly symptomatic effects for various diseases including cancer. This review discusses predominant modes of action and numerous molecular markers. Attention is paid to metal-induced generation of free radicals, the phenomenon of oxidative stress, damage to DNA, lipid, and proteins, responsive signal transduction pathways with major roles in cell growth and development, and roles of antioxidant enzymatic and DNA repair systems. Interaction of non-enzymatic antioxidants (carotenoids, flavonoids, glutathione, selenium, vitamin C, vitamin E, and others) with cellular oxidative stress markers (catalase, glutathione peroxidase, and superoxide dismutase) as well as certain regulatory factors, including AP-1, NF-?B, Ref-1, and p53 is also reviewed. Dysregulation of protective pathways, including cellular antioxidant network against free radicals as well as DNA repair deficiency is related to oncogenic stimulation. These observations provide evidence that emerging oxidative stress-responsive regulatory factors and DNA repair proteins are putative predictive factors for tumor initiation and progression.",
Arsenic,1030766,"Arsenic exposure through drinking water and its effect on pregnancy outcome in Bengali women Abstract: Twelve districts of the state of West Bengal, India are affected by arsenic (As) and millions of individuals are consuming As-contaminated groundwater. The probable adverse effects of As on pregnancy outcome (stillbirth and miscarriage) are yet to be properly studied. The present investigation is an attempt to understand the effects of As exposure on the pregnancy outcome in Bengali women exposed to As through drinking water and residing in different villages in North 24 Parganas District of West Bengal. The results show a significantly higher rate of stillbirths and miscarriages than those in the unexposed population.",
Arsenic,2278551,"Method for assessing lead, cadmium, mercury and arsenic in high-density polyethylene packaging and study of the migration into yoghurt and simulant Abstract: The purpose of this paper was to assess the concentration of lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As) in high-density polyethylene (HDPE) packaging intended for contact with yoghurt and the migration of these elements using the food itself and 3% acetic acid as a food simulant in accordance to ANVISA, the Brazilian Health Surveillance Agency. In order to perform this study, it was necessary to develop and validate a method by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. For method validation, the parameters linearity, limits of detection (LODs) and quantification (LOQs), accuracy and precision were determined. Fifteen commercial samples of yoghurt, marketed in Campinas - São Paulo (Brazil), were used for the analysis. The packaging and yoghurt were digested in high-pressure ashing equipment (HPA) and the migration of the elements into simulant were determined directly in the solution. The validated method proved adequate and the results obtained showed that all the packaging had levels of Hg and Cd below the LOQ, corresponding to 1.0 and 1.5 ?g l(-1), respectively. The highest levels of As and Pb were 0.87 and 462.3 mg kg(-1), respectively. The migration of these elements to the yoghurt after 45 days of contact at 4ºC was below the LOQ for all the samples assessed. The results of specific migration into 3% acetic acid simulant showed the concentrations of Cd, Hg and As below 5, 5 and 10 µg kg(-1), respectively, which are the maximum limits set by ANVISA. However, for three samples the packaging lid showed migration of Pb into simulant ranging from 30.6 to 40.2 ?g kg(-1), exceeding the limit set by ANVISA of 10 ?g kg(-1).",
Arsenic,2298692,"Is stability of the proximal tibiofibular joint important in the multiligament-injured knee? Abstract: BACKGROUND: The incidence of proximal tibiofibular joint instability in the setting of the multiligament-injured knee has not been previously reported. The integrity of the proximal tibiofibular joint is required to perform a fibular-based, lateral-sided knee reconstruction. QUESTIONS/PURPOSES: We report (1) the frequency of proximal tibiofibular joint instability in patients presenting with multiligament knee injuries and evaluate (2) our ability to restore stability to this joint, (3) patient-reported outcome scores, and (4) complications in patients surgically treated for proximal tibiofibular joint instability at the time of treatment of multiligament knee instability. METHODS: From 2005 to 2013, 124 patients (129 knees) sustaining multiligament knee injuries with Grade 3 instability to at least two ligaments were treated at our institution. We defined proximal tibiofibular joint instability as a dislocated or dislocatable proximal tibiofibular joint at the time of surgery. These patients underwent surgery to restore proximal tibiofibular joint stability and ligament reconstruction or repair and were followed with routine clinical examination, radiographs, and subjective outcome measures, including Lysholm and IKDC scores. Minimum followup was 12 months (mean, 32 months; range, 12-61 months). RESULTS: Twelve knees (12 patients, 9% of 129 knees) showed proximal tibiofibular joint instability. Knee stability in 10 patients was restored to Grade 1 or less in all surgically treated ligaments. No proximal tibiofibular joint instability has recurred. No patients have complained of ankle stiffness or pain. In the ten patients with subjective scores, mean Lysholm score was 75 (range, 54-95) and mean IKDC score was 58 (range, 22-78). There were four complications: one failed posterolateral corner reconstruction, one proximal tibiofibular joint screw removal secondary to pain over the screw head, one deep infection treated with serial irrigation and débridements with graft retention, and one closed manipulation secondary to arthrofibrosis and loss of ROM. CONCLUSIONS: In the setting of multiligament-injured knees, our series demonstrated a 9% incidence of proximal tibiofibular joint instability. The technique we describe successfully restored stability to the proximal tibiofibular joint and resulted in satisfactory patient-reported outcomes with low complication rates. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.",
Arsenic,1032687,"Nonmelanoma skin cancer in Japanese residents of Kauai, Hawaii Abstract: A prospective 3-year survey of nonmelanoma skin cancer in Japanese-American residents of the Hawaiian island of Kauai was conducted beginning in January 1983. The crude rate for basal cell and squamous cell carcinoma was 123/100,000, 88 times higher than the corresponding figure from Japan. This discrepancy may be attributed to an increase in ultraviolet exposure due to lifestyle and latitude, but arsenic exposure may also have played a role. Nonmelanoma skin cancer in Japanese in Hawaii appears to be a significant problem that has not been appreciated because these malignancies are not reportable to tumor registries.",
Arsenic,1015667,"Isolation and characterization of Staphylococcus sp. strain NBRIEAG-8 from arsenic contaminated site of West Bengal Abstract: Arsenic contaminated rhizospheric soils of West Bengal, India were sampled for arsenic resistant bacteria that could transform different arsenic forms. Staphylococcus sp. NBRIEAG-8 was identified by16S rDNA ribotyping, which was capable of growing at 30,000 mg l(-1) arsenate [As(V)] and 1,500 mg l(-1) arsenite [As(III)]. This bacterial strain was also characterized for arsenical resistance (ars) genes which may be associated with the high-level resistance in the ecosystems of As-contaminated areas. A comparative proteome analysis was conducted with this strain treated with 1,000 mg l(-1) As(V) to identify changes in their protein expression profiles. A 2D gel analysis showed a significant difference in the proteome of arsenic treated and untreated bacterial culture. The change in pH of cultivating growth medium, bacterial growth pattern (kinetics), and uptake of arsenic were also evaluated. After 72 h of incubation, the strain was capable of removing arsenic from the culture medium amended with arsenate and arsenite [12% from As(V) and 9% from As(III)]. The rate of biovolatilization of As(V) was 23% while As(III) was 26%, which was determined indirectly by estimating the sum of arsenic content in bacterial biomass and medium. This study demonstrates that the isolated strain, Staphylococcus sp., is capable for uptake and volatilization of arsenic by expressing ars genes and 8 new upregulated proteins which may have played an important role in reducing arsenic toxicity in bacterial cells and can be used in arsenic bioremediation.",
Arsenic,2278246,"Inorganic micropollutants removal by means of membrane processes: State of the art Abstract: A number of inorganic anions and metals, especially heavy metals, at certain conditions, have been found in potentially harmful concentrations in numerous water sources. The maximum permissible levels of these compounds, in drinking water and wastewaters discharged to environment, set by the WHO and a number of countries are very low (from mu g/dm(3) to a few mg/dm(3)). Several common treatment technologies, which are nowadays used for removal of inorganic contaminants from natural water supplies, represent serious exploitation problems. Membrane processes such as reverse osmosis and nanofiltration, ultrafiltration and microfiltration in integrated systems, Donnan dialysis and electrodialysis as well as membrane bioreactors, if properly selected, offer the advantage of producing high quality drinking water without inorganic substances as well as purified wastewater which can be drained off to natural water sources.",
Arsenic,1392394,"Selenium, Tellurium, and Osmium Abstract: The biological effects of occupational exposure to selenium (7782492), tellurium (13494809), osmium (7440042), and related compounds were reviewed and discussed. The chemical properties, occurrence, and industrial uses of these elements were described. Studies indicated that selenium may cause skin, mucous membrane, and respiratory irritation in exposed humans and that selenium-oxide (7446084) can destroy skin on contact. Treatment of selenium exposure depended upon the route of administration. Exposure to tellurium vapor or hydrogen-telluride (7783097) has resulted in respiratory irritation which can be fatal. Experimental evidence has suggested that ingested tellurium may act as a teratogen. The acute toxic effects of tellurium exposure were similar to those seen for arsenic, and no effective treatment was currently available. Osmium exposure has resulted in gastric and respiratory system irritation in experimental studies, and human exposure to osmium metal has resulted in fatalities. Exposure to osmium-tetroxide (20816120) has produced eye, pulmonary, and kidney damage.",
Arsenic,656917,"Arsenic inhibits the repair of DNA damage induced by benzo (a) pyrene Abstract: In order to study the effect of arsenic on DNA damage, Sprague–Dawley rats were dosed with sodium arsenite (10 mg/kg) with or without 800 ?g of benzo(a)pyrene (BP) by intramammilary injection. The animals were sacrificed on day 1, 3, 5, 10 and 27 and the mammary gland tissues were collected for DNA adduct measurement using a 32P post-labeling assay. Animals dosed with arsenic alone did not show any DNA adducts. DNA adduct levels in rats dosed with BP alone reached a maximum level by day 5, reducing to 13% of this level by day 27. Adduct levels in rats dosed with arsenic and BP also reached a maximum by day 5 but only 80% of the level observed in the BP group. However, 84% of this amount still remained by day 27. The First Nucleotide Change (FNC) technique was used for the screening of 115 samples of various tissues from mice that had been chronically exposed to sodium arsenate for over 2 years revealed that inorganic arsenic did not attack the two putative hotspots (codons 131 and 154) of the hOGG1 gene. These results support the hypothesis that arsenic exerts its biological activity through DNA repair inhibition.",
Arsenic,1030827,"Detection of mercury-, arsenic-, and selenium-containing proteins in fish liver from a mercury polluted area of Guizhou Province, China Abstract: Mercury (Hg)-, selenium (Se)-, and arsenic (As)- containing proteins in liver tissues of bighead carp and grass carp sampled from a mercury-polluted area of Wanshan, Guizhou Province, China, were separated by thin-layer isoelectric focusing. The relative content of Hg, Se, and As in protein bands was measured with synchrotron radiation x-ray fluorescence. The results indicated that there were at least 3 Hg-containing bands with pI 3.7, 4.8, and 6.2 in liver of bighead carp and 1 Hg-containing band with pI 6.2 in grass carp. Se and As were found in the Hg-containing bands 3.7 in bighead carp and 6.2 in grass carp. The bands may be corresponding to the antagonistic effect of Se against the toxicity of Hg and As. In addition, Hg and As often coexist in the same band, suggesting that the two elements may be involved in the same metabolic processes.",
Arsenic,1353462,Comparative Study of Holmium (III) Selective Sensors Based on Thiacalixarene and Calixarene Derivatives as an Ionophore Abstract: ,
Arsenic,628799,"DNA damage in leukocytes of workers occupationally exposed to arsenic in copper smelters Abstract: Inorganic arsenic (i-As) is a known human carcinogen; however, humans continue to be exposed to i-As in drinking water and in certain occupational settings. In this study, we used the Comet assay to evaluate DNA damage in the somatic cells of workers from three Polish copper smelters who were occupationally exposed to i-As. Blood samples were collected from 72 male workers and 83 unexposed male controls and used for the detection of DNA damage, oxidative DNA damage, and DNA damage after a 3-hr incubation in culture. Urine samples were collected to assess the level of exposure. The mean concentration of arsenic metabolites in urine [the sum of arsenite (AsIII), arsenate (AsV), monomethylarsenate (MMA) and dimethylarsenate (DMA)] and the concentrations of DMA (the main metabolite in urine) were higher in workers than in controls, but the differences were not statistically significant. By contrast, the level of DNA damage, expressed as the median tail moment, was significantly higher in the leukocytes of workers than in the controls. Comet assays conducted with formamidopyrimidine glycosylase (FPG) digestion to detect oxidative DNA damage indicated that oxidative lesions were present in leukocytes from both the exposed and control groups, but the levels of damage were significantly higher among the workers. Incubation of the cells in culture resulted in a significant reduction in the levels of DNA damage, especially among leukocytes from the workers, suggesting that the DNA damage was subject to repair. Our findings indicate that copper smelter workers have increased levels of DNA damage in somatic cells, suggesting a potential health risk for the workers. Although i-As was present in air samples from the smelters and in urine samples from workers, no clear association could be made between i-As exposure and the DNA damage. Copyright 2005 Wiley-Liss, Inc.",
Arsenic,1337684,"Arsenic interactions with a fullerene-like BN cage in the vacuum and aqueous phase Abstract: Adsorption of arsenic ions, As (III and V), on the surface of fullerene-like B(12)N(12) cage has been explored in vacuum and aqueous phase using density functional theory in terms of Gibbs free energies, enthalpies, geometry, and density of state analysis. It was found that these ions can be strongly chemisorbed on the surface of the cluster in both vacuum and aqueous phase, resulting in significant changes in its electronic properties so that the cluster transforms from a semi-insulator to a semiconductor. The solvent significantly affects the geometry parameters and electronic properties of the As/B(12)N(12) complexes and the interaction between components is considerably weaker in the aqueous phase than that in the vacuum.",
Arsenic,1519199,"Development of an early-tier laboratory bioassay for assessing the impact of orally-active insecticidal compounds on larvae of Coccinella septempunctata (Coleoptera: Coccinellidae) Abstract: Early-tier studies are the initial step in the environmental risk assessment of genetically engineered plants on nontarget arthropods. They are conducted in the laboratory where surrogate species are exposed to higher concentrations of the arthropod-active compound than those expected to occur in the field. Thus, early-tier tests provide robust data and allow to make general conclusions about the susceptibility of the surrogate to the test substance. We have developed an early-tier test for assessing the toxicity of orally-active insecticidal compounds to larvae of the ladybird beetle Coccinella septempunctata L. (Coleoptera: Coccinellidae). Using potassium arsenate and the protease inhibitor E-64 as model compounds, we validated the bioassay set-up for C. septempunctata. Sucrose solution containing the test compound was offered to larvae for 24 h on the first day of each of its four larval instars. Subsequently, larvae were fed ad libitum with Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs. Both compounds negatively affected C. septempunctata larval survival and development, and adult weight, indicating that the bioassay setup was able to detect dietary effects of insecticidal substances on the ladybird. Power analyses revealed that sample sizes of 20 or 45 per treatment are sufficient to detect 50 or 20% differences between the control and treatment groups, respectively, for the various measurement endpoints.",
Arsenic,1028785,"Effects on operant learning and brain acetylcholine esterase activity in rats following chronic inorganic arsenic intake Abstract: 1. Very young and adult Wistar rats were given As5+, 5 mg arsenic kg-1 body weight day-1 (sodium arsenate). 2. Operant learning was tested in a Skinner box at the end of exposure and, in the case of developing animals, also after a recovery period. 3. Acetylcholine esterase (AChE) activity was estimated in discrete brain regions of these animals. 4. The animals exposed to arsenic took longer to acquire the learned behaviour and to extinguish the operant. AChE activity was inhibited in some regions of the brain.",
Arsenic,1597305,"A baseline study of metals in cod (Gadus morhua) from the North Sea and coastal Norwegian waters, with focus on mercury, arsenic, cadmium and lead Abstract: This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and livers of 516 cod caught at 22 positions in the North Sea were analysed. An additional 687 cod were caught from 13 fjords and coastal areas along the coast of Norway. Three out of 1203 samples of muscle exceeded the maximum limit of 0.5mgHgkg(-1) wet weight set by the EU for foodstuffs. The mercury concentration in cod muscle was higher and the cadmium concentration in the liver was lower in the North Sea and coastal areas in the southern part of Norway than in the Barents Sea and coastal areas in the northern part of Norway. These differences are perhaps caused by differences in the cod diet.",
Arsenic,2347819,"Influence of iron content, surface area and charge distribution in the arsenic removal by activated carbons Abstract: Due to the high number of toxicological issues, the presence of asenic (V) in water supplies is a major problem of public concern. Adsorption by iron modified activated carbons stands as an interesting alternative for the removal of arsenic (V) from aqueous solutions. However, the question of which of the activated carbon properties have impact during arsenic (V) uptake has arisen. The influence of textural and chemical features of several activated carbons (AC), un-modified and modified with iron oxyhydroxide nanoparticles, for the removal of arsenic (V) from aqueous solution was studied. The surface area micropore volume, surface charge and iron content of 28 ACs were determined. Results showed that the S-BET of materials range from 388 to 1747 m(2)/g, the point of zero charge (PHpzc) from 3 to 11 and the iron content range from negligible to around 2%. A detailed data analysis demonstrated that the most important parameter of AC when removing arsenic (V) from water is the pH(pzc) (52.5% of contribution); however, the presence of iron is indispensable for enhancing the adsorption capacity (by 36.5%). An empirical model indicated that in order to effectively remove arsenic from water a basic AC with an iron content of about 1% is desirable. Arsenic (V) adsorption isotherms under normal conditions demonstrated that the materials studied have a great potential for water polishing. Finally it is suggested that the arsenate uptake by iron-modified AC is conducted by two simultaneous mechanisms: ligand interchange with iron oxyhydroxide particles and electrostatic attraction on basic AC.",
Arsenic,2278905,"Feasibility studies on arsenic removal from aqueous solutions by electrodialysis Abstract: The effectiveness of electrodialysis (ED) in removing inorganic arsenic (As) from aqueous solution was investigated. A tailor-made ED stack was used to perform current-voltage and optimization experiments in a recirculating batch mode. Samples were pre-oxidized with NaClO using 1:2 sample to oxidant weight ratio (RS:O) to transform 100% of As(III) to As(V) in 180 seconds. A high feed water conductivity of 1500 ?S/cm and a low feed water conductivity of 800?S/cm had limiting currents of 595 mA and 525 mA, respectively. Optimum experimental conditions that provided maximum As separation were applied potential (E) of 12 V, feed flow rate (Q) of 0.033 L/s, feed concentration (C) of 662.0 ?g L(-1), and operating time (t) of 45 min, the most significant ones were applied potential, feed concentration and operating time. Model confirmation experiments showed a good agreement with experimental results with only 0.031% error. The total As in the diluate stream was 4.0 ?g L(-1), consisting of an average of 3.0 ?g L(-1) As(V) and 1.0 ?g L(-1) As(III).",
Arsenic,1337602,"Arsenic increases Pi-mediated vascular calcification and induces premature senescence in vascular smooth muscle cells Abstract: Several mechanisms have been proposed to explain the vascular toxicity of arsenic. Some of them are described in this work, such as stress-induced premature senescence (SIPS), dedifferentiation, and medial vascular calcification, and they all affect vascular smooth muscle cells (VSMC). Rat aortic VSMC were treated with 1-100 µM of either sodium arsenate (As(V)), arsenite (As(III)), monomethylarsonic acid (MMA), or dimethylarsinic acid (DMA). None of the treatments induced VSMC calcification in the presence of 1 mM inorganic phosphate (Pi), but 1 µM As(III) did increase calcification when induced with 2.5 mM Pi. An LDH assay revealed that this increase was explained by a rise in cytotoxicity due to simultaneous incubation with 1 µM As(III) and 2.5 mM Pi. This calcification increase was also observed in the aortas of a vascular calcification model: 5/6 nephrectomized rats fed with a high Pi diet and treated with vitamin D(3). Several known mechanisms that might explain arsenic toxicity in our experimental model were discarded: apoptosis, oxidative stress, and inflammasome activation. Nevertheless, both senescence-associated ß-galactosidase (SA ß-gal) activity and p21 expression were increased by As(III), which reveals the induction of SIPS. As(III) also caused dedifferentiation of VSMC, as shown by the reduced expression of the VSMC markers SM22? and calponin. Senescence and gene expression were also observed in the aortas of healthy rats treated with 50 ppm As(V) in drinking water for one month. In conclusion, both premature senescence in aortic VSMC with phenotypic dedifferentiation and the increase of Pi-induced calcification are novel mechanisms of arsenic vasculotoxicity.",
Arsenic,1794814,"Role of chelating agents on release kinetics of metals and their uptake by maize from chromated copper arsenate-contaminated soil Abstract: Kinetic aspects of metal release were investigated to understand the effects of synthetic chelating agents (EDTA, EDDS and NTA) and low molecular weight (LMW) organic acids (oxalic and citric acids) on the release kinetics of Cr, Cu and As in chromated copper arsenate (CCA)-contaminated soil, as well as their uptake by maize (Zea mays L.). The results showed that the release of metals from soil was better described by parabolic diffusion, power function or simple Elovich model than by the first- and second-order models, indicating a heterogeneous diffusion of metals. Synthetic chelating agents afforded a higher release of Cu than that of LMW organic acids, whereas citric acid was the most effective chelating agent for Cr and As release. The most effective treatments for stimulating metal uptake in plant shoots were EDDS for Cu, EDTA for Cr, and citric acid for As, as indicated by the removal efficiencies of 0.046%, 0.036%, and 0.004%, respectively. However, Zea mays is not an attractive species for chelate-enhanced phytoremediation of CCA-contaminated soils due to its low phytoextraction rate, even in the presence of chelating agents and ligands.",
Arsenic,1339308,"Heavy metals and trace elements in hair and urine of a sample of arab children with autistic spectrum disorder Abstract: General information: Autism is a severe developmental disorder which involves social withdrawal, communication deficits, and stereotypic/repetitive behavior. The pathophysiological etiologies which precipitate autism symptoms remain elusive and controversial in many cases, but both genetic and environmental factors (and their interactions) have been implicated. While autism is considered multicausal, environmental factors have received significant attention. International discussion has ocused on neurotoxins such as mercury and lead, suggesting that these and other toxic metals contribute to the development of the disorder. An epidemiological study released in 2006 (Palmer et al.) linking Toxic Release Inventory (TRI) data on mercury to special education data in Texas reported a 61% increase in autism prevalence rates (or 17% adjusted) per 1000 pounds of mercury released into the environment (1). We attempted to further evaluate whether exposure to variable environmental contributes to the genesis of autistic spectrum disorder, and thus is a factor increasing the risk for developing autism symptoms in utero or in early childhood.Purpose: The purpose of this study is to examine possible environmental risk factors and sources of exposure to mercury and other heavy metals in children with autism spectrum disorder versus controls. Through laboratory diagnostics we are able to distinguish between present and past exposure (i.e. hair analysis measurements reflect past exposure), urinary excretion levels of unprovoked urine represent immediate exposure. By assessing a spectrum of trace elements and heavy metals in hair and urine of both autistic and control groups, we focused on the participants? past and present exposure.Methodology: The participants were 25 Autistic Spectrum Disorder (ASD) children (22 boys and 3 girls) between the age of 3 and 9 years. They were either diagnosed previously by other psychiatrist, psychologist, and developmental pediatrician or suspected by their parents as being autistic. All children were attendants to the Child Psychiatric Clinic in Erfan Psychiatric Hospital in Jeddah, KSA. Samples were collected during the period of June 2006 to March 2008. A control group of 25 children without any psychiatric or medical disorders was age-matched and sex-matched. All parents signed informed consent forms. All autistic children were subjected to a full clinical child psychiatric sheet for the diagnosis of autism spectrum disorder and exclusion of other psychiatric disorders according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM IV). The severity of autistic symptomatology was measured by the Childhood Autism Rating Scale (CARS) and Autism Behavior Checklist (ABC) using the Arabic versions. Both groups were subjected to the Questionnaire on Exposure to Heavy Metals, Physical Symptoms, and Child Development. Hair and baseline urine samples (i.e. unprovoked urine) were taken from both groups and sent to the German clinical and environmental laboratory Micro Trace Minerals Gmbh, for the detection of heavy metals and trace elements levels where metal testing was performed via ICP-MS spectroscopy utilizing cell technique. Results: By comparing the ASD Group to the Control Group, we found a statistically significant difference in the mean hair levels of arsenic, cadmium, barium, cerium and lead (p=0.01, 0.03, 0.003, 0.003, and 0.03 respectively), and in the mean hair levels of magnesium and zinc (p=0.001 and 0.003 respectively). There were also statistically significant differences in the mean urine levels of aluminum, barium, cerium, mercury, and lead (p=0.004, 002, 0.014, 0.006 and 0.004 respectively), and in the mean urine levels of copper and germanium (p=0.049 and 0.02 respectively). An agreement was found in both specimen (hair and urine) for barium and lead. The statistically significant differences in mean hair levels of arsenic, cadmium, and cerium were not supported by urine baseline levels. Also, the statistically significant magnesium and zinc levels of hair ere not supported by urine levels. A disagreement was also found with copper and germanium concentrations.",
Arsenic,2337127,"Green synthesis of a silver nanoparticle-graphene oxide composite and its application for As(III) detection Abstract: We report a facile and green synthetic approach to synthesize a silver nanoparticle (AgNPs)-graphene oxide (GO) composite using beta cyclodextrin as a stabilizing agent and ascorbic acid as a reducing agent. Further, we demonstrate its application as a highly sensitive and selective electrochemical sensor for selective determination of As(III) in the presence of other elements, such as Cu and some organic and inorganic molecules. The GO sheets provided the surface for the reduction of silver ions. The composite can be easily used for the construction of a disposable electrochemical sensor on a glassy carbon electrode (GCE) using a drop deposition method. The composite was characterized by scanning and transmission electron microscopies, energy dispersive X-ray spectroscopy, X-ray diffraction and electrochemical impedance spectroscopy. Cyclic voltammetry and anodic stripping voltammetry measurements were employed to evaluate the electrochemical properties of beta cyclodextrin stabilized AgNPs-GO/GCE towards arsenic(III) detection. The AgNPs-GO film exhibited distinctly higher activity for the anodic stripping analysis of As(III) compared to the GO film alone with approximately three times enhancement of the peak current. This nanostructured electrode applied for As(III) analysis displayed a wide linear range (13.33-375.19 nM), a high sensitivity (180.5(mu A mu M-1)) including a 0.24 nM detection limit. We demonstrate the real-life application of the developed sensor by selectively determining the As content in ground and river water samples.",
Arsenic,2149167,"Localization of SERBP1 in stress granules and nucleoli Abstract: SERBP1 (SERPINE1 mRNA binding protein 1) is an arginine methylated RNA binding protein and the modification affects protein interaction and intracellular localization. In the present study, we show that under normal growth condition without stress, SERBP1 interacts with some arginine methylated and stress granule-associated proteins such as hnRNPA1, FMRP, FXR1 in an RNA-dependent manner. We also show that after arsenite treatment, a fraction of full-length SERBP1 protein co-localizes with the typical stress granule marker TIA-1in the cytoplasmic SGs. Truncated SERBP1 with the N-terminal, middle RG or C-terminal deletions, or else any single domain segment containing the N-terminal, middle or C-terminal region, was recruited to SGs upon arsenite treatment but with reduced efficiency. Besides, upon arsenite treatment, diffuse cytoplasmic localization of SERBP1 was shifted to nuclear-dominant and concentrated nucleolar distribution. Similar distribution was observed when cells were treated with a methylation inhibitor adenosine periodate (AdOx) and was also detected in the N- or C-terminal domain deletions and all three single domain fragments even without stress induction. We further demonstrate that AdOx treatment delays the association/dissociation of SERBP1 with SGs. Hypomethylation retains SERBP1 in the nucleus/nucleolus regardless of arsenite treatment. Our study indicates that arginine methylation is correlated with the recruitment of SERBP to as well as its retention in stress granules and nucleoli. Our study is the first report of an RNA binding protein that can be shifted simultaneously to cytoplasmic SGs and nucleoli, two RNP-concentrated subcellular compartments, upon stress. This article is protected by copyright. All rights reserved.",
Arsenic,1033433,"Exposure to arsenic and respiratory cancer. A reanalysis Abstract: This paper is a reanalysis of data on the respiratory cancer mortality experience of 2,802 men who worked one year or more during the period 1940-1964 at a copper smelter in Tacoma, Washington. Exposure estimates presented earlier have been recalculated and perhaps improved. While the previous analysis showed only a weak relation between respiratory cancer and arsenic exposure, use of new data shows a much stronger relation--but one that is concave downward and not ordinarily considered for environmental exposure and cancer. This new analysis indicates that arsenic is probably more potent as a carcinogen than indicated by other studies. It also demonstrates the distinction between airborne arsenic and the bioavailability of arsenic, and the importance of this distinction for risk assessment. When a dose-response relation is based on airborne concentrations of arsenic, it is clearly concave downward, but when based on urine concentrations, it appears to be linear.",
Arsenic,1024681,"Laser-activated fluoride treatment of enamel against an artificial caries challenge: comparison of five wavelengths Abstract: <strong>BACKGROUND: </strong>Laser-activated fluoride (LAF) therapy with 488 nm laser energy has been shown previously to increase the resistance of human enamel and dentine to acid dissolution in laboratory models of dental caries. The aims of this study were to examine whether LAF therapy, conducted using a range of wavelengths in the visible and near infrared regions, can protect human dental enamel from an artificial cariogenic challenge.<br /><br /><strong>MATERIALS AND METHODS: </strong>Buccal and lingual surfaces of extracted sound, molar and premolar teeth were used to prepare matched pairs of enamel slabs (N=10 per group). After application of neutral sodium fluoride gel (12300 ppm F ion), slab surfaces were lased (energy density 15 J/cm2; spot size 5mm, wavelength 532, 633, 670, 830 or 1064nm), then exposed to an artificial cariogenic challenge for a period of seven days. The Vicker's hardness number (VHN) was recorded before and after laser treatment and again following the cariogenic challenge. Negative controls did not receive laser exposure.<br /><br /><strong>RESULTS: </strong>All wavelengths of laser light examined provided an effective LAF effect, compared with the unlased negative control surfaces.<br /><br /><strong>CONCLUSION: </strong>Using this in vitro model, we conclude that the action spectrum of the LAF effect extends across the visible and near-infrared regions of the spectrum.",
Arsenic,1337358,"Concentration of arsenic in water, sediments and fish species from naturally contaminated rivers Abstract: Arsenic (As) may occur in surface freshwater ecosystems as a consequence of both natural contamination and anthropogenic activities. In this paper, As concentrations in muscle samples of 10 fish species, sediments and surface water from three naturally contaminated rivers in a central region of Argentina are reported. The study area is one of the largest regions in the world with high As concentrations in groundwater. However, information of As in freshwater ecosystems and associated biota is scarce. An extensive spatial variability of As concentrations in water and sediments of sampled ecosystems was observed. Geochemical indices indicated that sediments ranged from mostly unpolluted to strongly polluted. The concentration of As in sediments averaged 6.58 ?g/g ranging from 0.23 to 59.53 ?g/g. Arsenic in sediments barely followed (r = 0.361; p = 0.118) the level of contamination of water. All rivers showed high concentrations of As in surface waters, ranging from 55 to 195 ?g/L. The average concentration of As in fish was 1.76 ?g/g. The level of contamination with As differed significantly between species. Moreover, the level of bioaccumulation of As in fish species related to the concentration of As in water and sediments also differed between species. Whilst some fish species seemed to be able to regulate the uptake of this metalloid, the concentration of As in the large catfish Rhamdia quelen mostly followed the concentration of As in abiotic compartments. The erratic pattern of As concentrations in fish and sediments regardless of the invariable high levels in surface waters suggests the existence of complex biogeochemical processes behind the distribution patterns of As in these naturally contaminated ecosystems.",
Arsenic,1338680,"Arsenic, chromium and mercury removal using mussel shell ash or a sludge/ashes waste mixture Abstract: Different batches of valued mussel shell and waste mussel shell ash are characterised. Shell ash has pH?&gt;?12 and high electrical conductivities (between 16.01 and 27.27 dS?m(-1)), while calcined shell shows pH values up to 10.7 and electrical conductivities between 1.19 and 3.55 dS?m(-1). X-ray fluorescence, nitric acid digestion and water extractions show higher concentrations in shell ash for most parameters. Calcite is the dominant crystalline compound in this ash (95.6 %), followed by aragonite. Adsorption/desorption trials were performed for mussel shell ash and for a waste mixture including shell ash, sewage sludge and wood ash, showing the following percentage adsorptions: Hg(II) &gt;94 %, As(V) &gt;96 % and Cr(VI) between 11 and 30 % for shell ash; Hg(II) &gt;98 %, As(V) &gt;88 % and Cr(VI) between 30 and 88 % for the waste mixture. Hg and As desorption was &lt;5 % for both shell ash and the waste mixture, while Cr desorption was between 92 and 45 % for shell ash, and between 19 and 0 % for the mixture. In view of that, mussel shell ash and the mixture including shell ash, sewage sludge and wood ash could be useful for Hg(II) and As(V) removal.",
Arsenic,1936029,"Mechanisms of chromium and arsenite adsorption by amino-functionalized SBA-15 Abstract: The adsorption of Cr(VI) and As(III) by amino-functionalized SBA-15 (NH2-SBA-15) from single and binary systems were investigated in this work. The effects of pH and temperature on the adsorption of NH2-SBA-15 were studied. Adsorption kinetics, isotherm model, and thermodynamics were studied to analyze the experimental data. pH 2 was the optimum condition for the adsorption of Cr(VI) and pH 4 for As(III) adsorption. Increasing temperature had a positive effect on the removal of both Cr(VI) and As(III). The Freundlich isotherm model can depict the adsorption process best. The pseudo-second-order kinetic model fitted well with the kinetic data of Cr(VI) and As(III) in the single-component system. In the binary system, the adsorption of As(III) by NH2-SBA-15 was slightly enhanced with the presence of Cr(VI); however, As(III) had no obvious effect on the removal of Cr(VI). Regeneration experiments indicated that 0.1 mol/L NaHCO3 was an efficient desorbent for the recovery of Cr(VI) and As(III) from NH2-SBA-15; the desorption rates for Cr(VI) and As(III) were 91.6 and 33.59 %, respectively. After five recycling cycles, the removal rates were 88 and 7 % for Cr(VI) and As(III) adsorption by NH2-SBA-15, respectively.",
Arsenic,1355410,Arsenic therapy shows promise in acute promyelocytic leukaemia Abstract: ,
Arsenic,1030742,"Arsenite and its metabolites, MMA(III) and DMA(III), modify CYP3A4, PXR and RXR alpha expression in the small intestine of CYP3A4 transgenic mice Abstract: Arsenic is an environmental pollutant that has been associated with an increased risk for the development of cancer and several other diseases through alterations of cellular homeostasis and hepatic function. Cytochrome P450 (P450) modification may be one of the factors contributing to these disorders. Several reports have established that exposure to arsenite modifies P450 expression by decreasing or increasing mRNA and protein levels. Cytochrome P450 3A4 (CYP3A4), the predominant P450 expressed in the human liver and intestines, which is regulated mainly by the Pregnane X Receptor-Retinoid X Receptor alpha (PXR-RXR alpha) heterodimer, contributes to the metabolism of approximately half the drugs in clinical use today. The present study investigates the effect of sodium arsenite and its metabolites monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)) on CYP3A4, PXR, and RXR alpha expression in the small intestine of CYP3A4 transgenic mice. Sodium arsenite treatment increases mRNA, protein and CYP3A4 activity in a dose-dependent manner. However, the increase in protein expression was not as marked as compared to the increase in mRNA levels. Arsenite treatment induces the accumulation of Ub-protein conjugates, indicating that the activation of this mechanism may explain the differences observed between the mRNA and protein expression of CYP3A4 induction. Treatment with 0.05 mg/kg of DMA(III) induces CYP3A4 in a similar way, while treatment with 0.05 mg/kg of MMA(III) increases mostly mRNA, and to a lesser degree, CYP3A4 activity. Sodium arsenite and both its metabolites increase PXR mRNA, while only DMA(III) induces RXR alpha expression. Overall, these results suggest that sodium arsenite and its metabolites induce CYP3A4 expression by increasing PXR expression in the small intestine of CYP3A4 transgenic mice.",
Arsenic,2343498,"A novel low-cost detection method for screening of arsenic in groundwater Abstract: In the present work, a novel and simple detection system for As inorganic species contained in groundwater is presented. To reach the required detection limit, the proposed methodology is based on two steps: first is the transport and preconcentration of the inorganic arsenic species using a polymer inclusion membrane (PIM) system and second is the formation of a coloured complex, the  absorbance of which is measured. Different parameters related to the membrane composition and the transport kinetics have been studied, and it was found that membranes made of polyvinyl chloride (PVC) as a polymer, and Aliquat 336 as a carrier, ensured efficient arsenic transport when the carrier content was at least 31 % (w/w). The implementation of the designed PIM in a special device that contained only 5 mL of the stripping solution (0.1 M NaCl) allowed As preconcentration from a 100-mL water sample, thus facilitating its detection with the colorimetric method. The new method developed here was validated, and its analytical figures of merit were determined, i.e. limit of detection of 4.5 ?g L(-1) at 820 nm and a relative standard deviation within the range 8-10 %. Finally, the method was successfully applied to the analysis of different water samples from Catalonia region with naturally occurring As.",
Arsenic,1365837,"Heat shock glycoprotein GP50: product of the retinoic acid-inducible J6 gene Abstract: High intracellular levels of heat shock proteins and enhanced protein glycosylation are two phenomena closely associated with the cellular stress response. GP50 is the major heat-induced glycoprotein in Chinese hamster ovary (CHO) cells; however, GP50 is not well characterized, and its function is unknown. J6 is a gene originally identified in F9 murine teratocarcinoma cells after exposure to retinoic acid. In this study we show that J6 is heat-inducible and codes for a protein that shares characteristics with GP50. Western blotting of CHO cell homogenates, using a J6 polyclonal antibody, showed a single band with a molecular weight identical to that of GP50. Thermotolerant cells showed increased levels of the J6/GP50 protein. Heat-shocked CHO cells also accumulated transiently high levels of J6 mRNA between 2 and 7 h following 10 min at 45 degrees C. These induction kinetics are similar to those for GP50 labeling with D-[3H]mannose and to the activation of major heat shock genes, e.g., hsp70. Hybrid selection of J6 mRNA from CHO cells, followed by in vitro translation, produced a single band on SDS-PAGE with a molecular weight identical to that of deglycosylated GP50. Neither cellular proliferation (exponential growth versus plateau phase) nor the specific heat shock temperature (41.5 degrees C versus 45 degrees C) had significant effects on J6 induction by heat stress. Stress conditions other than hyperthermia, including ethanol, arsenite, and hypoxia, increased J6 mRNA levels. Conversely, J6 mRNA was reduced by quercetin, brefeldin A, okadaic acid, uv, and hydrogen peroxide. Our data support the hypothesis that J6 is a heat shock gene with a gene product identical to the polypeptide moiety of GP50.",
Arsenic,1016313,"Glutathione reductase inhibition and methylated arsenic distribution in Cd1 mice brain and liver Abstract: Inorganic arsenic exposure via drinking water has been associated with cancer and serious injury in various internal organs, as well as with peripheral neuropathy and diverse effects in the nervous system. Alterations in memory and attention processes have been reported in exposed children, whereas adults acutely exposed to high amounts of inorganic arsenic showed impairments in learning, memory, and concentration. Glutathione (GSH) is extensively involved in the metabolism of inorganic arsenic, and both arsenite and its methylated metabolites have been shown to be potent inhibitors of glutathione reductase (GR) in vitro. Brain would be more susceptible to GR inhibition because of the decreased activities of superoxide dismutase (SOD) and catalase reported in this tissue. To investigate whether GR inhibition could be documented in vivo, we determined the activity and levels of GR in brain as well as in liver, the main organ of arsenic metabolism in mice exposed to 2.5, 5, or 10 mg/kg/day of sodium arsenite over a period of 9 days. In contrast to what has been observed in vitro, significant inhibition of the expression and activity of GR was observed only at the highest concentration used (10 mg/kg/day) in both organs. Although the disposition of arsenicals was higher in liver, significant amounts of inorganic and methylated arsenic forms were determined in the brain of exposed animals. The formation of monomethylarsenic (MMA) and dimethylarsenic (DMA) metabolites in the brain was confirmed by incubating brain slices for 24, 48, and 72 h with sodium arsenite.",
Arsenic,1251009,"Soil pollution assessment and identification of hyperaccumulating plants in chromated copper arsenate (CCA) contaminated sites, Korea Abstract: In recent decades, heavy metal contamination in soil adjacent to chromated copper arsenate (CCA) treated wood has received increasing attention. This study was conducted to determine the pollution level (PL) based on the concentrations of Cr, Cu and As in soils and to evaluate the remediative capacity of native plant species grown in the CCA contaminated site, Gangwon Province, Korea. The pollution index (PI), integrated pollution index (IPI), bioaccumulation factors (BAF(shoots) and BAF(roots)) and translocation factor (TF) were determined to ensure soil contamination and phytoremediation availability. The 19 soil samples from 10 locations possibly contaminated with Cr, Cu and As were collected. The concentrations of Cr, Cu and As in the soil samples ranged from 50.56-94.13 mg kg(-1), 27.78-120.83 mg kg(-1), and 0.13-9.43 mg kg(-1), respectively. Generally, the metal concentrations decreased as the distance between the CCA-treated wood structure and sampling point increased. For investigating phytoremediative capacity, the 19 native plant species were also collected in the same area with soil samples. Our results showed that only one plant species of Iris ensata, which presented the highest accumulations of Cr (1120 mg kg(-1)) in its shoot, was identified as a hyperaccumulator. Moreover, the relatively higher values of BAF(shoot) (3.23-22.10) were observed for Typha orientalis, Iris ensata and Scirpus radicans Schk, suggesting that these plant species might be applicable for selective metal extraction from the soils. For phytostabilization, the 15 plant species with BAF(root) values&gt;1 and TF values&lt;1 were suitable; however, Typha orientalis was the best for Cr.",
Arsenic,1252670,"Release of arsenic from semiconductor wafers Abstract: The production of integrated circuits and other semiconductor devices requires the introduction of impurities or dopants into the crystal lattice of a silicon substrate. This &quot;doping&quot; or junction formation is achieved through one of two processes: thermal diffusion or ion implantation. Ion implantation, the more contemporary and more accurate of the two processes, accomplishes junction formation by bombarding selected areas of the silicon wafer with a beam of dopant ions. Inorganic arsenic, which is regulated by the Occupational Health and Safety Administration (OSHA) as a carcinogen, is frequently used as dopant material. Silicon wafers are found to emit inorganic arsenic following ion implantation. Data collected during this experiment demonstrate that arsenic is released over a 3.5-hour period following implantation and that the total amount of arsenic emitted may approach 6.0 micrograms per 100 wafers processed within 4 hours after implantation. The discovery and quantification of this phenomenon suggest that newly implanted silicon wafers are a potential source of arsenic contamination--a source that may impact both the quality of the work environment and the integrated circuit product.",
Arsenic,1597415,"Monoisoamyl 2,3-dimercaptosuccinic acid attenuates arsenic induced toxicity: Behavioral and neurochemical approach Abstract: Chronic exposure to arsenic in drinking water is associated with skin lesions, neurological effects, hypertension and high risk of cancer. The treatment in use at present employs administration of thiol chelators, such as meso-2,3-dimercaptosuccinic acid (DMSA) which are compromised with number of limitations due to their lipophobic nature. To address this problem, therapeutic efficacy of monoisoamyl meso-2,3-dimercaptosuccinic acid (MiADMSA), an analog of DMSA having lipophilic character, was examined against chronic arsenic poisoning in rats. Adult male Wistar rats were orally exposed to arsenic (2mg sodium arsenite/kg body weight) for 10 weeks followed by treatment with MiADMSA (50mg/kg, orally, once daily for 5 consecutive days). As-exposed rats showed significant differences in behavioral functions (open field behavior, total locomotor activity, grip strength and exploratory behavior) and water maze learning. Further, the biochemical studies performed on three brain regions (cerebellum, cortex and hippocampus) also showed significant elevation in malondialdehyde (MDA) levels with a concomitant decrease in the oxidative stress marker enzymes Mn-superoxide dismutase (Mn-SOD), Cu/Zn-superoxide dismutase (Cu/Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST). The alterations were more pronounced in cortex compared to cerebellum and hippocampus. The results showed that MiADMSA significantly reversed the As-induced alterations in behavior and biochemical variables suggestive of oxidative injury.",
Arsenic,1337322,"Arsenic exposure and oral cavity lesions in Bangladesh Abstract: OBJECTIVE:: To evaluate the relationship between arsenic exposure and oral cavity lesions among an arsenic-exposed population in Bangladesh. METHODS:: We carried out an analysis utilizing the baseline data of the Health Effects of Arsenic Exposure Longitudinal Study, which is an ongoing population-based cohort study to investigate health outcomes associated with arsenic exposure via drinking water in Araihazar, Bangladesh. We used multinomial regression models to estimate the risk of oral cavity lesions. RESULTS:: Participants with high urinary arsenic levels (286.1 to 5000.0 ?g/g) were more likely to develop arsenical lesions of the gums (multinomial odds ratio = 2.90; 95% confidence interval, 1.11 to 7.54), and tongue (multinomial odds ratio = 2.79; 95% confidence interval, 1.51 to 5.15), compared with those with urinary arsenic levels of 7.0 to 134.0 ?g/g. CONCLUSIONS:: Higher level of arsenic exposure was positively associated with increased arsenical lesions of the gums and tongue.",
Arsenic,1677396,"Caged Gammarus fossarum (Crustacea) as a robust tool for the characterization of bioavailable contamination levels in continental waters: Towards the determination of threshold values Abstract: We investigated the suitability of an active biomonitoring approach, using the ecologically relevant species Gammarus fossarum, to assess trends of bioavailable contamination in continental waters. Gammarids were translocated into cages at 27 sites, in the Rhône-Alpes region (France) during early autumn 2009. Study sites were chosen to represent different physico-chemical characteristics and various anthropic pressures. Biotic factors such as sex, weight and food availability were controlled in order to provide robust and comparable results. After one week of exposure, concentrations of 11 metals/metalloids (Cd, Pb, Hg, Ni, Zn, Cr, Co, Cu, As, Se and Ag) and 38 hydrophobic organic substances including polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyles (PCBs), pentabromodiphenylethers (PBDEs) and organochlorine pesticides, were measured in gammarids. All metals except Ag, and 33 organic substances among 38 were quantified in G. fossarum, showing that this species is relevant for chemical biomonitoring. The control of biotic factors allowed a robust and direct inter-site comparison of the bioavailable contamination levels. Overall, our results show the interest and robustness of the proposed methodological approach for assessing trends of bioavailable contamination, notably for metals and hydrophobic organic contaminants, in continental waters. Furthermore, we built threshold values of bioavailable contamination in gammarids, above which measured concentrations are expected to reveal a bioavailable contamination at the sampling site. Two ways to define such values were investigated, a statistical approach and a model fit. Threshold values were determined for almost all the substances investigated in this study and similar values were generally derived from the two approaches. Then, levels of contaminants measured in G. fossarum at the 27 study sites were compared to the threshold values obtained using the model fit. These threshold values could serve as a basis for further implementation of quality grids to rank sites according to the extent of the bioavailable contamination, with regard to the applied methodology.",
Arsenic,1936182,"Procedia Earth and Plantetary Science Hydrogeochemical characteristics of high As and high F groundwater in Hangjinhouqi, Hetao Plain, China Abstract: ",
Arsenic,1509364,"Sustainability of groundwater usage in northern China: dependence on palaeowaters and effects on water quality, quantity and ecosystem health Abstract: ",
Arsenic,2337112,"Antimony(V) removal from water by hydrated ferric oxides supported by calcite sand and polymeric anion exchanger Abstract: We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides (HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents (denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3 would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 mu g/L to below 5 mu g/L (the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.",
Arsenic,1019041,"Histopathology of skin lesions in chronic arsenic toxicity--grading of changes and study of proliferative markers Abstract: Chronic arsenic toxicity (CAT) manifests predominantly as cutaneous lesions in the form of melanosis, keratosis and neoplastic changes. We have studied skin biopsies from 42 patients of CAT. Histological study of H/E stained sections showed--hyperkeratosis in 13, parakeratosis in 13, acanthosis in 12, papillomatosis in 24, elongation of reteridges in 21, increased basal pigmentation in 27 and dysplastic changes in 8 cases. Squamous cell carcinoma was present in 2, basisquamous in 1 and basal cell carcinoma in 1 case. Changes of skin lesions after drug DMSA and DMPS therapy compared to placebo were studied. The result was inconclusive. Proliferative activity of skin lesions in CAT were studied by AgNOR stain to assess the biological behaviour of the lesions. AgNOR score showed--normal control 1.08, benign changes (e.g. Hyperkeratosis, parakeratosis, acanthosis, papillomatosis etc.) without dysplasia--1.35, mild to moderate dysplasia--1.735, severe dysplasia--3.0 and carcinoma--3.56. Thus, AgNOR score gives some idea on the biological behaviour of CAT lesions. It is suggested that AgNOR staining should be done regularly along with H&amp;E staining for proper assessment of the cases.",
Arsenic,2337061,"Concentrations and health risks of lead, cadmium, arsenic, and mercury in rice and edible mushrooms in China (vol 147, pg 147, 2013) Abstract: ",
Arsenic,1519058,"Arsenic exposure and incidence of type 2 diabetes in Southwestern American Indians Abstract: Association of urinary arsenic concentration with incident diabetes was examined in American Indians from Arizona who have a high prevalence of type 2 diabetes and were screened for diabetes between 1982 and 2007. The population resides where drinking water contains arsenic at concentrations above federally recommended limits. A total of 150 nondiabetic subjects aged ?25 years who subsequently developed type 2 diabetes were matched by year of examination and sex to 150 controls who remained nondiabetic for ?10 years. Total urinary arsenic concentration, adjusted for urinary creatinine level, ranged from 6.6 µg/L to 123.1 µg/L, and inorganic arsenic concentration ranged from 0.1 µg/L to 36.0 µg/L. In logistic regression models adjusted for age, sex, body mass index, and urinary creatinine level, the odds ratios for incident diabetes were 1.11 (95% confidence interval (CI): 0.79, 1.57) and 1.16 (95% CI: 0.89, 1.53) for a 2-fold increase in total arsenic and inorganic arsenic, respectively. Categorical analyses suggested a positive relationship between quartiles of inorganic arsenic and incident diabetes (P = 0.056); post-hoc comparison of quartiles 2-4 with quartile 1 revealed 2-fold higher odds of diabetes in the upper quartiles (OR = 2.14, 95% CI: 1.19, 3.85). Modestly elevated exposure to inorganic arsenic may predict type 2 diabetes in American Indians. Larger studies that include measures of speciated arsenic are required for confirmation.",
Arsenic,2347671,"Impact of human activity and natural processes on groundwater arsenic in an urbanized area (South China) using multivariate statistical techniques Abstract: Anthropogenic factors resulted from the urbanization may affect the groundwater As in urbanized areas. Groundwater samples from the Guangzhou city (South China) were collected for As and other parameter analysis, in order to assess the impact of urbanization and natural processes on As distribution in aquifers. Nearly 25.5 % of groundwater samples were above the WHO drinking water standard for As, and the As concentrations in the granular aquifer (GA) were generally far higher than that in the fractured bedrock aquifer (FBA). Samples were classified into four clusters by using hierarchical cluster analysis. Cluster 1 is mainly located in the FBA and controlled by natural processes. Anthropogenic pollution resulted from the urbanization is responsible for high As concentrations identified in cluster 2. Clusters 3 and 4 are mainly located in the GA and controlled by both natural processes and anthropogenic factors. Three main mechanisms control the source and mobilization of groundwater As in the study area. Firstly, the interaction of water and calcareous rocks appears to be responsible for As release in the FBA. Secondly, reduction of Fe/Mn oxyhydroxides and decomposition of organic matter are probably responsible for high As concentrations in the GA. Thirdly, during the process of urbanization, the infiltration of wastewater/leachate with a high As content is likely to be the main source for groundwater As, while NO3 (-) contamination diminishes groundwater As.",
Arsenic,627434,"The accumulation and toxicity of methylated arsenicals in endothelial cells: Important roles of thiol compounds Abstract: Excess intake of arsenic is known to cause vascular diseases as well as skin lesions and cancer in humans. Recent reports suggest that trivalent methylated arsenicals, which are intermediate metabolites in the methylation process of inorganic arsenic, are responsible for the toxicity and carcinogenicity of environmental arsenic. We investigated acute toxicity and accumulation of monomethylarsonic acid (MMA(V)), dimethylarsinic acid (DMA(V)), trimethylarsine oxide (TMAO), and monomethylarsonous acid diglutathione (MMA(III) (GS)(2)) in rat heart microvessel endothelial (RHMVE) cells. MMA(V) (LC(50) = 36.6 mM) and DMA(V) (LC(50) = 2.54 mM) were less toxic than inorganic arsenicals (cf. LC(50) values for inorganic arsenite (iAs(III)), and inorganic arsenate (iAs(V)) was reported to be 36 and 220 microM, respectively, in RHMVE cells. TMAO was essentially not toxic. However, MMA(III) (GS)(2) was highly toxic (LC(50) = 4.1 microM). The order of cellular arsenic accumulation of those four organic arsenic compounds was MMA(III) (GS)(2) >> MMA(V) > DMA(V) > TMAO. MMA(III) (GS)(2) was efficiently taken up by the cells and cellular arsenic content increased with the concentration of MMA(III) (GS)(2) in culture medium. N-acetyl-l-cysteine (NAC) reduced cellular arsenic content in DMA(V)-exposed cells and also decreased the cytotoxicity of DMA(V), whereas it changed neither cellular arsenic content nor the viability in MMA(V)-exposed cells. mRNA levels of heme oxygenase-1 (HO-1) were decreased by NAC in DMA(V)-exposed, but MMA(V)-exposed cells. Buthionine sulfoximine (BSO), a cellular glutathione (GSH) depleting agent, enhanced the cytotoxicity of MMA(V). However, BSO reduced, rather than enhanced, the cytotoxicity of DMA(V). These results suggest that intracellular GSH modulated the toxic effects of arsenic in opposite ways for MMA(V) and DMA(V). Even though intracellular GSH decreased the cytotoxicity of MMA(V), extracellularly added GSH enhanced the cytotoxicity of MMA(V). The use of high-performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometric analyses suggested that a small amount of MMA(V) was converted to MMA(III) (GS)(2) in the presence of GSH. These results suggest that MMA(III) (GS)(2) is highly toxic compared to other arsenic compounds because of faster accumulation of this species by cells, in addition to having the toxic nature of methylated trivalent organic arsenics.",
Arsenic,2279042,"Statistical analysis of causes of death (2005-2010) in villages of Simav Plain, Turkey, with high arsenic levels in drinking water supplies Abstract: The purpose of this research was to compare the causes of death in five villages situated in Simav Plain, Turkey during 2005-2010 where different arsenic levels were detected in drinking water supplies. Since groundwater in Simav plain had arsenic concentrations that ranged between 7.1 and 833.9 ppb, a two phase research was formulated. In the first phase, public health surveys were conducted with 1003 villagers to determine the distribution of diseases. In the second phase, verbal autopsy surveys and official death records were used to investigate the causes of death. Totally, 402 death cases were found in the study area where cardiovascular system diseases (44%) and cancers (15.2%) were major causes. Cancers of lung (44.3%), prostate (9.8%), colon (9.8%) and stomach (8.2%) were comparably higher in villages with high arsenic levels in drinking water supplies. Furthermore, the majority of cases of liver, bladder and stomach cancers were observed in villages with high arsenic levels.",
Arsenic,1677577,"Phytoremediation potential of Pteris vittata L. under the combined contamination of As and Pb: beneficial interaction between As and Pb Abstract: The frequent co-existence of arsenic (As) and lead (Pb) necessitates the investigation of clean-up technologies for multi-metal(loid)s. Field survey and hydroponic experiments were conducted to elucidate the co-accumulation of As and Pb in Pteris vittata L. The P. vittata population isolated from a Pb-Zn mine in Yunnan province, China is a potential extractor of As and Pb co-contamination. Hydroponic experiment found that the highest frond As and Pb concentrations in mining population of P. vittata reached 12.2 and 0.99 g kg(-1), respectively. The interaction between As and Pb in P. vittata was further more disclosed. Pb (2 mg L(-1)) improved the frond As concentration by 60 to 150 % in mining populations of P. vittata. Micro-X-ray absorption spectroscopy indicated that under the combined exposure of As and Pb, the As content in the rhizoid epidermis increased by about 10-fold, and the As(V) percentage increased in each rhizoid tissue, as compared with that under As exposure alone. The co-absorption of As and Pb on the epidermis and the enhanced transportation of As(V) from epidermis into the rhizoid were suggested to contribute to the increased As accumulation.",
Arsenic,1033532,"Heavy metal exposure from foods Abstract: The Food and Drug Administration has a continuing program of monitoring foods for their content of lead, cadmium, mercury, zinc, arsenic, and selenium to determine trends of increasing or decreasing levels. The monitoring protocol is that of the Total Diet Study, in which &quot;market baskets&quot; of typical foods and beverages consumed by 15- to 20-year-old American males are collected in various geographical locations at regular intervals during the year, divided into food classes, composited, and analyzed. Cadmium has the most widespread distribution of the six heavy metals and mercury the most limited. The analytical values for lead may be underestimated because of limitations of the methodology; these do not apply to the other five elements. A tabulation by year shows that the levels of these elements in foods do not vary significantly from one year to the next. Average intakes of lead, cadmium, and mercury are below the WHO/FAO tolerable intakes for adults; such tolerable intakes have not been established for arsenic and selenium. Increases in concentrations of these elements in foods would be considered undesirable, however.",
Arsenic,2064189,"Evaluation of dietary arsenic exposure and its biomarkers: A case study of West Bengal, India Abstract: Few reports are available that characterize daily arsenic exposure through water and diet among people living in groundwater-contaminated regions and correlate it with biomarkers. The present study describes the total individual arsenic exposure and arsenic level in urine and hair of such an arsenic-exposed population in West Bengal. Demographic characteristics and the total daily arsenic intake through water and diet were determined in 167 (Group-1 participants selected from arsenic endemic region) and 69 (Group-2 participants selected from arsenic non-endemic region) in West Bengal. Out of 167 Group-1 participants 78 (Group-1A) had arsenical skin lesions while 89 Group-1B) had no such lesion. Arsenic level in water samples as well as diet, urine and hair samples, collected from all the individual participants, were estimated. The mean value of estimated total arsenic content from water and diet was 349 (range: 20-1615) ?g/day in 167 (Group-1) participants living in As endemic region [As in water: mean value 54 (range:BDL-326) ?g/L] and 36 (range:12-120) ?g/day in 69 (Group-2) participants living in As non-endemic region (As in water: below detection level (BDL), < 0.3 ?g/L). Estimated mean arsenic level in urine in these two groups of participants was 116 (range: 6-526) ?g/L and 17 (range: BDL-37) ?g/L and in hair was 1.0 (range: 0.22-3.98) mg/Kg and 0.16 (range: 0.06-0.37) mg/Kg, respectively. Multiple regressions analysis in Group-1 participants showed that total arsenic intake was associated significantly with urinary and hair arsenic level. The estimated regression coefficient was 0.0022 (95% confidence interval, C.I: 0.0016, 0.0028; P < 0.001) and 0.0024 (95% C.I: 0.0021, 0.003; P < 0.001), respectively. In sub group analysis, higher median urinary arsenic value relative to arsenic intake through water and diet was observed in 78 Group-1A subjects with skin lesion compared to urinary arsenic value in 89 Group-1B subjects without skin lesions, though there was a marginal difference of median total arsenic intake in these two groups. This study showed that significant elevation of arsenic level in urine and hair was associated with elevated arsenic intake through water and diet in people living in arsenic endemic region (Group-1), while these values were low in people living in non-endemic region (Group-2). Those with skin lesions were found to have higher arsenic in urine and hair compared to those without skin lesion with similar arsenic intake through water and diet.",
Arsenic,1244037,"Evidence of antiapoptotic properties of Pleurotus florida lectin against chronic arsenic toxicity in renal cells of rats Abstract: Chronic arsenic exposure results in toxicity in humans and causes many toxicologic manifestations. Apoptosis was measured by cell adhesion, morphologic alterations, cell proliferation, terminal deoxyuridine triphosphate nick-end labeling (TUNEL), and caspase-3/CPP32 fluorometric protease assay. Results of the present study suggested that arsenic administration in rats caused apoptosis by elevating morphologic alterations, TUNEL-positive nuclei, caspase-3 activity, and DNA damage and by reducing cell adhesion and cell proliferation in a time-dependent manner. The apoptosis in renal cells of arsenic-exposed rats reverted to normal values after coadministration of mushroom lectin. This study provided significant evidence that Pleurotus florida lectin has an antiapoptotic property by protecting from arsenic-induced toxicity. The beneficial effect of Pleurotus florida lectin was proportional to its duration of exposure. This finding might be of therapeutic benefit in people suffering from chronic exposure to arsenic from natural sources, a global problem that is especially relevant to millions of people on the Indian subcontinent.",
Arsenic,2337145,"Physical, Chemical, and Biological Methods for the Removal of Arsenic Compounds Abstract: Arsenic is a toxic metalloid which is widely distributed in nature. It is normally present as arsenate under oxic conditions while arsenite is predominant under reducing condition. The major discharges of arsenic in the environment are mainly due to natural sources such as aquifers and anthropogenic sources. It is known that arsenite salts are more toxic than arsenate as it binds with vicinal thiols in pyruvate dehydrogenase while arsenate inhibits the oxidative phosphorylation process. The common mechanisms for arsenic detoxification are uptaken by phosphate transporters, aquaglyceroporins, and active extrusion system and reduced by arsenate reductases via dissimilatory reduction mechanism. Some species of autotrophic and heterotrophic microorganisms use arsenic oxyanions for their regeneration of energy. Certain species of microorganisms are able to use arsenate as their nutrient in respiratory process. Detoxification operons are a common form of arsenic resistance in microorganisms. Hence, the use of bioremediation could be an effective and economic way to reduce this pollutant from the environment.",
Arsenic,1327284,"Immediate-early gene induction by the stresses anisomycin and arsenite in human osteosarcoma cells involves MAPK cascade signaling to Elk-1, CREB and SRF Abstract: Cellular stress activates multiple mitogen-activated protein kinase (MAPK) cascades and immediate-early gene (IEG) transcription. To address how these events are linked, we investigated the endogenous signaling/transcription factor network driving IEG activation by arsenite and anisomycin in the human osteosarcoma cell line HOS/TE-85. Induction of IEG transcription by both stresses corresponded temporally with the phosphorylation of the regulatory factors Elk-1 and cAMP response element-binding protein (CREB), along with activation of the extracellular signal-regulated kinase (ERK), stress-activated protein kinase (SAPK) and p38 MAPK cascades. To assess the role of the different cascades, they were selectively inhibited with PD98059, SP600125 and SB203580, respectively. This implicated all three cascades in Elk-1 phosphorylation after arsenite treatment, whereas ERK and SAPK inhibition diminished this, and IEG mRNA levels, downstream of anisomycin. SB blocked phosphorylation of both serum response factor (SRF) and CREB, and strongly reduced IEG activation by both stresses. Combining PD with SB further reduced arsenite induction of IEG transcription. Thus, all three MAPK cascades mediate anisomycin- and arsenite-induced signaling to IEG promoters in HOS cells through the differential targeting of Elk-1, SRF and CREB.",
Arsenic,1597324,"Kinetics of heavy metal inhibition of 1,2-dichloroethane biodegradation in co-contaminated water Abstract: Sites co-contaminated with heavy metals and 1,2-DCA may pose a greater challenge for bioremediation, as the heavy metals could inhibit the activities of microbes involved in biodegradation. Therefore, this study was undertaken to quantitatively assess the effects of heavy metals (arsenic, cadmium, mercury, and lead) on 1,2-DCA biodegradation in co-contaminated water. The minimum inhibitory concentrations (MICs) and concentrations of the heavy metals that caused half-life doubling (HLDs) of 1,2-DCA as well as the degradation rate coefficient (k1 ) and half-life (t½ ) of 1,2-DCA were measured and used to predict the toxicity of the heavy metals in the water microcosms. An increase in heavy metal concentration resulted in a progressive increase in the t½ and relative t½ and a decrease in k1 . The MICs and HLDs of the heavy metals were found to vary, depending on the heavy metals type. In addition, the presence of heavy metals was shown to inhibit 1,2-DCA biodegradation in a dose-dependent manner, with the following order of decreasing inhibitory effect: Hg(2+) ?&gt;?As(3+) ?&gt;?Cd(2+) ?&gt;?Pb(2+) . Findings from this study have significant implications for the development of bioremediation strategies for effective degradation of 1,2-DCA and other related compounds in wastewater co-contaminated with heavy metals.",
Arsenic,627400,"Induction of oxyradicals by arsenic: Implication for mechanism of genotoxicity Abstract: Although arsenic is a well-established human carcinogen, the mechanisms by which it induces cancer remain poorly understood. We previously showed arsenite to be a potent mutagen in human-hamster hybrid (A(L)) cells, and that it induces predominantly multilocus deletions. We show here by confocal scanning microscopy with the fluorescent probe 5',6'-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate that arsenite induces, within 5 min after treatment, a dose-dependent increase of up to 3-fold in intracellular oxyradical production. Concurrent treatment of cells with arsenite and the radical scavenger DMSO reduced the fluorescent intensity to control levels. ESR spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPOL-H) as a probe in conjunction with superoxide dismutase and catalase to quench superoxide anions and hydrogen peroxide, respectively, indicates that arsenite increases the levels of superoxide-driven hydroxyl radicals in these cells. Furthermore, reducing the intracellular levels of nonprotein sulfhydryls (mainly glutathione) in A(L) cells with buthionine S-R-sulfoximine increases the mutagenic potential of arsenite by more than 5-fold. The data are consistent with our previous results with the radical scavenger DMSO, which reduced the mutagenicity of arsenic in these cells, and provide convincing evidence that reactive oxygen species, particularly hydroxyl radicals, play an important causal role in the genotoxicity of arsenical compounds in mammalian cells.",
Arsenic,711029,"Reliability of spot urine samples in assessing arsenic exposure Abstract: Urinary arsenic concentration is often used as a biomarker of arsenic exposure. First morning void (FMV) and spot urine samples from 131 participants in southeastern Michigan were analyzed using an HPLC-IC-PMS system for six different arsenic species: arsenobetaine (AsB), arsenite (As[III]), arsenate (As[V]), methylarsonous acid MMA[III], methylarsenic acid MMA[V], and dimethylarsenic DMA[V]. Bland-Altman plots, intraclass correlation coefficients (ICCs), and Pearson correlation procedures were used to evaluate the relationship between the arsenic species in FMV and spot urine collections after normalizing the samples by specific gravity. DMA[III] and MMA[III] were not detected in any of the samples. The sum of As[III], As[V], MMA[V], and DMA[V] was designated SumAs. The ICC between SumAs in FMV and SumAs in spot samples was 0.90. The ICC showed that 90% of variation comes from between individuals and not within individuals. A significant correlation (r=0.80 p<0.001) was observed between FMV and spot samples for SumAs. The spot sample were a good predictor of the MMA[V] (r=0.83 p<0.0001), and DMA[V] (r=0.77 p<0.0001) in the FMV sample. These associations suggest that either FMV or spot samples can be used as an adequate bioindicator of arsenic metabolites in human urine. The benefit of using spot urine samples, instead of 24-h or FMV urine samples, is the potential reduction in budgetary and logistic requirements in epidemiological studies.",
Arsenic,1017909,"Lifetime exposure to arsenic in residential drinking water in Central Europe Abstract: Objective Methods and results are presented for an arsenic exposure assessment integral to an epidemiological case–control study of arsenic and cancer—the European Commission funded ASHRAM (Arsenic Health Risk Assessment and Molecular Epidemiology) study carried out in some counties of Hungary, Romania and Slovakia. Methods The exposure history of each participant (N = 1,392) was constructed by taking into account how much water they consumed (as water, in drinks and in food), sources of drinking water in their various residences over their lifetime, and the concentrations of arsenic in their various water supplies measured by Hydride GenerationAtomic Absorption Spectrometry (HG-AAS). Concentrations of arsenic in previous water supplies were either derived from contemporary analyses of the same source, or from routine historical data from measurements performed by the authorities in each country. Using this approach, 80% of the recorded lifetime residential history was matched to an arsenic concentration. Seven indices of current, life time, and peak exposure were calculated. Results The exposure indices were all log-normally distributed and the mean and median lifetime average concentrations were in Hungary 14.7 and 13.3 g l¡1, Romania 3.8 and 0.7 g l¡1 and in Slovakia 1.9 and 0.8 g l¡1, respectively. Overall 25% of the population had average concentrations over 10 g l¡1 and 8% with exposure over 50 g l¡1. Conclusions Careful assessment of arsenic in drinking water supplies (both current and previous) enabled the majority of study participants’ cumulative lifetime of potential exposure to arsenic in residential water to be characterised.",
Arsenic,1344492,"Determination of arsenic in edible oils by direct graphite furnace atomic absorption spectrometry Abstract: A direct analytical method of arsenic content in edible oil with graphite furnace atomic absorption spectrophotometer was studied. Edible oil was diluted with n-heptane followed by the determination of arsenic with Zeeman graphite furnace atomic absorption spectrophotometer and transverse heated graphite atomizer (THGA). The arsenic organic AAS standard solution was used as calibration standard, and his (benzonitrile) dichloro palladium solution was used as a matrix modifier. The results showed that the optimal ashing and atomizing temperatures were 1200 °C and 2300 °C, respectively. The detection limit was estimated to be 0.010 ppm, and the percentages of recovery for the spike of 0.05, 0.10 and 0.20 ppm arsenic to salad oil, fish oil, palm oil, and lard were 91.2~94.3%, 94.7~95.6%, 94.2~96.7% and 93.3~94.1%, respectively. With the use of this method, thirty edible oils were analyzed and the arsenic contents were found to be below the detection limits.",
Arsenic,1252638,Iatrogenic peripheral corneal disease Abstract: ,
Arsenic,1936164,Comparing two operating configurations in a full-scale arsenic removal plant. Case study: Guatemala Abstract: ,
Arsenic,1337651,"A new arsenate reductase involved in arsenic detoxification in Anabaena sp. PCC7120 Abstract: In silico analysis followed by experimental validation leads us to propose that the predicted protein All0195 of Anabaena sp. PCC7120 showing enhanced expression under sodium arsenate (Na(2)HAsO(4)) stress belongs to the thioredoxin superfamily with structural similarity to bacterial arsenate reductase. The All0195 protein demonstrated C-X-TC-X-K, NTSG-X(2)-YR, and D-X(2)-L-X-KRP as functional motifs that show similarity to seven known bacterial arsenate reductase family protein homologs with Cys, Arg, and Pro as conserved residues. In view of physicochemical properties, such as aliphatic index, ratio of Glu?+?Lys to Gln?+?His, and secondary structure, it was evident that All0195 was also a thermostable protein. The predicted three-dimensional structure on molecular docking with arsenate oxyanion ([Formula: see text]) revealed its interaction with conserved Cys residue as also known for other bacterial arsenate reductase. In silico derived properties were experimentally attested by cloning and heterologous expression of all0195. Furthermore, this protein functionally complemented the arsenate reductase-deficient sodium arsenate-hypersensitive phenotype of Escherichia coli strainWC3110 (?arsC) and depicted arsenate reductase activity on purification. In view of the above properties, All0195 appears to be a new arsenate reductase involved in arsenic detoxification in Anabaena sp. PCC7120.",
Arsenic,1359765,"The effect of arsenic on the thermal tolerance of newly hatched muskellunge fry (Esox masquinongy) Abstract: HEEP COPYRIGHT: BIOL ABS. The temperature tolerance, Critical Thermal Maxima (CTM), was significantly reduced when newly hatched muskellunge fry were reared in tanks containing 0.05, 1.0 and 5.0 ppm As as sodium arsenite (NaAsO2). During swim-up (8-14 days post-hatch), CTM decreased from 32.5? to 30.5? C for fry exposed to 0.05 ppm As, from 32.2? to 30.0? C for fry in 1.0 ppm As and from 31.3? to 29.3? C for fry in 5.0 ppm. The CTM for the fry exposed to As remained depressed from the onset of swim-up until the experiment was terminated. The control group also displayed a drop in CTM during swim-up from 32.4? to 30.3? C but the CTM then slowly recovered and increased to 31.8? C on day 15. Swim-up began in all tanks on day 8 and was accompanied by a rapid increase in mortality in those fry exposed to As. Mortality (50%) was reached 2 days after swim-up began at 5.0 ppm As, 4 days after swim-up began at 1.0 ppm and 5 days after the onset of swim-up for 0.05 ppm. All fish exposed to As died within 7 days after the onset of swim-up. Control fish completed swim-up in 3 days (11 days after hatching), began to feed and appeared normal.",
Arsenic,95267,"Transfer of antimony and arsenic to the developing organism Abstract: The transfer of 73As and 125SB to the developing mouse organism was studied in the following ways. a)A diet containing the isotopes was given from the day of the vaginal plug and the radioactivity in uterus, ovaries and different maternal organs was determined 2,4, and 6 days after initiation of feeding. b)The isotopes were injected i.p. during organogenesis at day 12, and the transfer into the fetus as well as activity in maternal organs were followed for a period of 7 days. c)The radioactive diet was supplied during the entire pregnancy and 15 days thereafter. The radioactivity in the females was followed for 150 days, that in the litter for 50 days. Components of turnover of less than a day, less than a week and several months can be discerned in the adult for both isotopes and transfer to the fetus occurs during organogenesis. Less antimony than arsenic is transferred from food during fetal life. After birth, arsenic as well as antimony are taken up by the newborn via the milk.",
Arsenic,2088354,"Mechanism and diastereoselectivity of arsenic ylide mediated cyclopropanation: A theoretical study Abstract: The mechanism and diastereoselectivity of cyclopropanation reactions of arsenic ylides with enones have been investigated using density functional theory (DFT) calculations. The reactions of two different arsenic ylides, semistabilized (Ph) and stabilized (COMe), with enone have been considered. Calculations reveal that the transoid mode of addition is more favoured than the cisoid mode of addition in both reactions. Steric interactions induced by ylidic substituents and the methyl group of enones, and weak C–H?O hydrogen bond interactions are mainly responsible for the inherent stability difference between the addition transition states. The initial addition is found to be the diastereoselectivity-determining step for both semistabilized and stabilized ylides. The slight preferences for the formation of cis-cyclopropanes over trans-cyclopropanes in both cases is explained on the basis of weak H-bonding interactions and steric interactions encumbered on the diastereomeric transition states.",
Arsenic,2337229,"A prospective cohort study of the association between drinking water arsenic exposure and self-reported maternal health symptoms during pregnancy in Bangladesh Abstract: <strong>BACKGROUND: </strong>Arsenic, a common groundwater pollutant, is associated with adverse reproductive health but few studies have examined its effect on maternal health.<br /><br /><strong>METHODS: </strong>A prospective cohort was recruited in Bangladesh from 2008-2011 (N?=?1,458). At enrollment (&lt;16 weeks gestational age [WGA]), arsenic was measured in personal drinking water using inductively-coupled plasma mass spectrometry. Questionnaires collected health data at enrollment, at 28 WGA, and within one month of delivery. Adjusted odds ratios (aORs) and 95% confidence intervals (95% CI) for self-reported health symptoms were estimated for each arsenic quartile using logistic regression.<br /><br /><strong>RESULTS: </strong>Overall, the mean concentration of arsenic was 38 ?g/L (Standard deviation, 92.7 ?g/L). A total of 795 women reported one or more of the following symptoms during pregnancy (cold/flu/infection, nausea/vomiting, abdominal cramping, headache, vaginal bleeding, or swollen ankles). Compared to participants exposed to the lowest quartile of arsenic (?0.9 ?g/L), the aOR for reporting any symptom during pregnancy was 0.62 (95% CI?=?0.44-0.88) in the second quartile, 1.83 (95% CI?=?1.25-2.69) in the third quartile, and 2.11 (95% CI?=?1.42-3.13) in the fourth quartile where the mean arsenic concentration in each quartile was 1.5 ?g/L, 12.0 ?g/L and 144.7 ?g/L, respectively. Upon examining individual symptoms, only nausea/vomiting and abdominal cramping showed consistent associations with arsenic exposure. The odds of self-reported nausea/vomiting was 0.98 (95% CI: 0.68, 1.41), 1.52 (95% CI: 1.05, 2.18), and 1.81 (95% CI: 1.26, 2.60) in the second, third and fourth quartile of arsenic relative to the lowest quartile after adjusting for age, body mass index, second-hand tobacco smoke exposure, educational status, parity, anemia, ferritin, medication usage, type of sanitation at home, and household income. A positive trend was also observed for abdominal cramping (P for trend &lt;0.0001). A marginal negative association was observed between arsenic quartiles and odds of self-reported cold/flu/infection (P for trend?=?0.08). No association was observed between arsenic and self-reported headache (P for trend?=?0.19).<br /><br /><strong>CONCLUSION: </strong>Moderate exposure to arsenic contaminated drinking water early in pregnancy was associated with increased odds of experiencing nausea/vomiting and abdominal cramping. Preventing exposure to arsenic contaminated drinking water during pregnancy could improve maternal health.",
Arsenic,2347746,"Chitosan-Immobilized Pumice for the Removal of As(V) from Waters Abstract: A novel sorbent, chitosan-immobilized pumice, has been prepared for the sorption of As(V) from waters prior to its determination by hydride generation atomic absorption spectrometry. The success of the immobilization has been checked with such characterization techniques as scanning electron microscopy, thermal gravimetric analysis, and elemental analysis. Points of zero charge of the sorbents were determined with potentiometric mass titration. Batch-type equilibration studies have shown that the novel sorbent can be employed at a wide pH range resulting in quantitative sorption (&gt;90 %) at pH 3.0-7.0 and greater than 70 % sorption at pH &gt;8.0. These results demonstrate the advantage of immobilizing chitosan onto pumice, because, under the same conditions, pumice displays &lt;20 % sorption toward As(V), whereas chitosan gives approximately 90% sorption only at pH 3.0. The validity of the method was verified through the analysis of ultrapure, bottled drinking, and tap water samples spiked with arsenate; the respective sorption percentages of 93.2 (+/- 0.7), 89.0 (+/- 1.0), and 80.9 (+/- 1.3) were obtained by batch-type equilibration. Arsenic sorption was also examined in the presence of common interfering ions resulting in competing effects of PO43- and NO3- on As(V) adsorption.",
Arsenic,711047,"Time course of arsenic species in the brain and liver of mice after oral administration of arsenate Abstract: The understanding of the biomethylation process of arsenic is essential to uncover the mechanisms of arsenic toxicity. This work analyzes the time course of arsenic species in the brain and liver of adult mice, after a single oral administration of three arsenate doses [2.5, 5.0 and 10 mg As(V)/kg]. Quantification of arsenic species was performed by means of liquid chromatography coupled to atomic fluorescence 2, 5, 8, 12 and 24 h after administration. The results show that 2 h after arsenate administration inorganic arsenic arrives to the liver and its concentration diminishes gradually until becoming non-detectable at 12 h. Arsenic takes longer to appear in the brain and it is present only as dimethyl arsinic acid. Since arsenic concentration decreases in liver while it increases in the brain, this suggests that the arsenic metabolite reaches the brain after formation in the liver. Importantly, the fact that dimethyl arsinic acid is no longer present after 24 h suggests the existence of a mechanism to clear this metabolite from brain tissue.",
Arsenic,1339143,"Assessment of solid phase microfiber extraction fibers for the monitoring of volatile organoarsinicals emitted from a plant-soil system Abstract: Phytoremediation, the use of plants and microbes to clean up inorganic and organic pollutants, has shown great promise as an inexpensive and feasible form of remediation. More recently, studies have shown that some plants have an amazing capacity to volatilize contaminants and can be an effective remediation strategy if the chemicals released are non-toxic. Arsenic contamination and remediation has drawn great attention in the scientific community. However, its toxicity also varies depending on its form. We evaluated, optimized, and then utilized a solid phase microfiber extraction (SPME) head space sampling technique to characterize the organoarsinical emissions from rabbitfoot grass (Polypogon monspeliensis) in arsenic treated soils to determine if the potentially more toxic organic forms of arsenic (AsH(3), AsH(2)CH(3), AsH(CH(3))(2), and As(CH(3))(3)) were being emitted from the plant-soil system. The SPME fiber that proved best fitted for this application was the DVB/CAR/PDMS fiber with a 45min sampling period. We did detect and confirm the emissions of dimethylchloroarsine (AsCl(CH(3))(2)) and pentamethylarsine (As(CH(3))(5)). However, it was determined that the more toxic organic forms of arsenic were not released during phytovolatilization.",
Arsenic,453907,"Mortality experience of male workers at a UK tin smelter Abstract: Background Between 1937 and 1991, Capper Pass and Sons Limited operated a tin smelter complex in North Humberside, UK, at which employees were potentially exposed to a number of substances, including lead, arsenic, cadmium and natural series radionuclides. Decommissioning and site clearance continued until 1995. Between 1967 and 1995 the company was a subsidiary of Rio Tinto plc. Aims The aim was to identify any significant excess, or deficits, in mortality among former employees that might be attributable to factors associated with occupation. Methods We defined a cohort of 1462 males who had been employed for at least 12 months between 1/11/1967 and 28/7/1995, followed-up through to 31/12/2001. The mortality of the cohort was compared against that expected for both national and regional populations. Results Mortality from all causes and all cancers did not differ from that expected. Mortality from ischaemic heart disease showed a deficit and mortality from lung cancer showed a statistically significant excess. Mortality from smoking related diseases other than lung cancer showed a non-significant deficit. Conclusions The pattern of lung cancer mortality is consistent with the hypothesis that the risk of lung cancer has been enhanced by occupational exposure to one or more carcinogens, the effect of which diminishes with time since exposure. The deficit in ischaemic heart disease may be attributed to a protective effect from manual labour. The results provide no evidence for attribution of other excess or deficits in mortality to factors associated with employment.",
Arsenic,1021552,"Evaluation of hydrochemical changes due to intensive aquifer exploitation: case studies from Mexico Abstract: The impact of intensive aquifer exploitation has been observed in numerous places around the world. Mexico is a representative example of this problem. In 2010, 101 out of the 653 aquifers recognized in the country, showed negative social, economic, and environmental effects related to intensive exploitation. The environmental effects include, among others, groundwater level decline, subsidence, attenuation, and drying up of springs, decreased river flow, and deterioration of water quality. This study aimed at determining the hydrochemical changes produced by intensive aquifer exploitation and highlighting water quality modifications, taking as example the Valle de Toluca, Salamanca, and San Luis Potosi aquifers in Mexico's highlands. There, elements such as fluoride, arsenic, iron, and manganese have been detected, resulting from the introduction of older groundwater with longer residence times and distinctive chemical composition (regional flows). High concentrations of other elements such as chloride, sulfate, nitrate, and vanadium, as well as pathogens, all related to anthropogenic pollution sources (wastewater infiltration, irrigation return flow, and atmospheric pollutants, among others) were also observed. Some of these elements (nitrate, fluoride, arsenic, iron, and manganese) have shown concentrations above Mexican and World Health Organization drinking water standards.",
Arsenic,627457,"Chronic arsenic exposure and risk of infant mortality in two areas of Chile Abstract: Chronic arsenic exposure has been associated with a range of neurologic, vascular, dermatologic, and carcinogenic effects. However, limited research has been directed at the association of arsenic exposure and human reproductive health outcomes. The principal aim of this study was to investigate the trends in infant mortality between two geographic locations in Chile: Antofagasta, which has a well-documented history of arsenic exposure from naturally contaminated water, and Valparaíso, a comparable low-exposure city. The arsenic concentration in Antofagasta's public drinking water supply rose substantially in 1958 with the introduction of a new water source, and remained elevated until 1970. We used a retrospective study design to examine time and location patterns in infant mortality between 1950 and 1996, using univariate statistics, graphical techniques, and Poisson regression analysis. Results of the study document the general declines in late fetal and infant mortality over the study period in both locations. The data also indicate an elevation of the late fetal, neonatal, and postneonatal mortality rates for Antofagasta, relative to Valparaíso, for specific time periods, which generally coincide with the period of highest arsenic concentration in the drinking water of Antofagasta. Poisson regression analysis yielded an elevated and significant association between arsenic exposure and late fetal mortality [rate ratio (RR) = 1.7; 95% confidence interval (CI), 1.5-1.9], neonatal mortality (RR = 1.53; CI, 1.4-1.7), and postneonatal mortality (RR = 1.26; CI, 1.2-1.3) after adjustment for location and calendar time. The findings from this investigation may support a role for arsenic exposure in increasing the risk of late fetal and infant mortality.",
Arsenic,2298697,"Factors affecting temporal variability of arsenic in groundwater used for drinking water supply in the United States Abstract: The occurrence of arsenic in groundwater is a recognized environmental hazard with worldwide importance and much effort has been focused on surveying and predicting where arsenic occurs. Temporal variability is one aspect of this environmental hazard that has until recently received less attention than other aspects. For this study, we analyzed 1245 wells with two samples per well. We suggest that temporal variability, often reported as affecting very few wells, is perhaps a larger issue than it appears and has been masked by datasets with large numbers of non-detect data. Although there was only a slight difference in arsenic concentration variability among samples from public and private wells (p=0.0452), the range of variability was larger for public than for private wells. Further, we relate the variability we see to geochemical factors-primarily variability in redox-but also variability in pH and major-ion chemistry. We also show that in New England there is a weak but statistically significant indication that seasonality may have an effect on concentrations, whereby concentrations in the first two quarters of the year (January-June) are significantly lower than in the second two quarters (July-December) (p&lt;0.0001). In the Central Valley of California, though not statistically significant (p=0.4169), arsenic concentration is lower in the first quarter of the year but increases in subsequent quarters. In both regions, these changes appear to follow groundwater levels. It is possible that this difference in arsenic concentrations is related to groundwater level changes, pumping stresses, evapotranspiration effects, or perhaps mixing of more oxidizing, lower pH recharge water in wetter months. Focusing on the understanding the geochemical conditions in aquifers where arsenic concentrations are concerns and causes of geochemical changes in the groundwater environment may lead to a better understanding of where and by how much arsenic will vary over time.",
Arsenic,2064187,"Mouse assay for determination of arsenic bioavailability in contaminated soils Abstract: A mouse assay for measuring the relative bioavailability (RBA) of arsenic (As) in soil was developed. In this study, results are presented of RBA assays of 16 soils, including multiple assays of the same soils, which provide a quantitative assessment of reproducibility of mouse assay results, as well as a comparison of results from the mouse assay with results from a swine and monkey assay applied to the same test soils. The mouse assay is highly reproducible; three repeated assays on the same soils yielded RBA estimates that ranged from 1 to 3% of the group mean. The mouse, monkey, and swine models yielded similar results for some, but not all, test materials. RBA estimates for identical soils (nine test soils and three standard reference materials [SRM]) assayed in mice and swine were significantly correlated (r?=?0.70). Swine RBA estimates for 6 of the 12 test materials were higher than those from the mouse assay. RBA estimates for three standard reference materials (SRM) were not statistically different (mouse/swine ratio ranged from 0.86-1). When four test soils from the same orchard were assessed in the mouse, monkey, and swine assays, the mean soil As RBA were not statistically different. Mouse and swine models predicted similar steady state urinary excretion fractions (UEF) for As of 62 and 74%, respectively, during repeated ingestion doses of sodium arsenate, the water-soluble As form used as the reference in the calculation of RBA. In the mouse assay, the UEF for water soluble As(V) (sodium arsenate) and As(III) (sodium [meta] arsenite) were 62% and 66%, respectively, suggesting similar absolute bioavailabilities for the two As species. The mouse assay can serve as a highly cost-effective alternative or supplement to monkey and swine assays for improving As risk assessments by providing site-specific assessments of RBA of As in soils.",
Arsenic,1020888,"Community wells to mitigate the arsenic crisis in Bangladesh Abstract: <strong>OBJECTIVE: </strong>To monitor the effectiveness of deep community wells in reducing exposure to elevated levels of arsenic in groundwater pumped from shallower aquifers.<br /><br /><strong>METHODS: </strong>Six community wells ranging in depth from 60 m to 140 m were installed in villages where very few of the wells already present produced safe water. By means of flow meters and interviews with villagers carrying water from the community wells, a study was made of the extent to which these were used during one year. The results were compared with household and well data obtained during a previous survey in the same area.<br /><br /><strong>FINDINGS: </strong>The mean arsenic concentration in water pumped from wells already in use in the villages where the community wells, were installed was 180 +/- 140 micrograms/l (n = 956). Monthly sampling for 4-11 months showed that arsenic levels in groundwater from five of the six newly installed wells were consistently within the WHO guideline value of 10 micrograms/l for drinking-water. One of these wells met the Bangladesh standard of 50 micrograms/l arsenic but failed to meet the WHO guideline values for manganese and uranium in drinking-water. The community wells were very popular. Many women walked hundreds of metres each day to fetch water from them. On average, 2200 litres were hand-pumped daily from each community well, regardless of the season.<br /><br /><strong>CONCLUSION: </strong>A single community well can meet the needs of some 500 people residing within a radius of 150 m of it in a densely populated village. Properly monitored community wells should become more prominent in campaigns to reduce arsenic exposure in Bangladesh. Between 8000 and 10,000 deep community wells are needed to provide safe water for the four to five million people living in the most severely affected parts of the country.",
Arsenic,1352464,EFFECT OF COMBINED ACTION OF SELENIUM AND ARSENIC ON SUSPENSION CULTURE OF MICE FIBROBLASTS Abstract: ,
Arsenic,1579292,"Arsenic upregulates the expression of angiotensin II Type I receptor in mouse aortic endothelial cells Abstract: Although chronic arsenic exposure is a well-known risk for cardiovascular disease and has a strong correlation with hypertension, the molecular pathogenesis underlying arsenic exposure-induced hypertension remains poorly understood. To delineate the pathogenesis, we examined changes in the mRNA levels of 2 angiotensin II Type I receptor (AT1R) subtypes, AT1AR and AT1BR, in a mouse aortic endothelial cell line, END-D. Quantitative real-time PCR analysis revealed significant increases in the mRNA levels of 2 AT1R subtypes, AT1AR and AT1BR following sodium arsenite (SA) treatment. Flow cytometry analysis revealed that SA increases the generation of reactive oxygen species (ROS) in a dose-dependent manner. In addition, western blot analysis revealed that SA enhances the phosphorylations of c-Jun N-terminal kinases (JNK) and activated protein 1 (AP-1). These phosphorylations were inhibited by N-acetylcysteine (NAC), an anti-oxidant. Finally, SA-induced AT1R expression was found to be prevented both by NAC and specific JNK inhibitor, SP6001325, strongly indicating that AT1R upregulation is a result of the ROS-mediated activation of the JNK signaling pathway. Taken together, our results indicate that arsenic indeed upregulates the AT1R expression, thus highlighting a role of arsenic-induced aberrant AT1R signaling in the pathogenesis of hypertension.",
Arsenic,1356819,"P53 Protein Expression In Human Lymphocytes Abstract: In response to various types of stress the p53 tumor-suppressor protein exerts antiproliferative effects, including growth arrest and apoptosis. In normal tissues, wild type protein is present at low levels due to its short half-life, thus p53 protein is tightly controlled and maintained at low levels in cells by constant ubiquitination and proteasomal degradation. Alterations in the balance of induction / degradation could confer differences in the response to genotoxic effects. It has been proposed that p53 protein induction might be used as an indicator of genotoxic/ carcinogenic damage in cell lines. Since lymphocytes are the main cells used for human monitoring, p53 expression could become another important end-point in the evaluation of in vivo exposures. Blood was obtained from 10 healthy donors and p53 expression was evaluated by immunoblot in non-stimulated and stimulated peripheral lymphocytes. In all but one sample, p53 levels increased when mitotic index (MI) decreased. However, p53 was expressed in non-proliferating lymphocytes of this one sample. Thus, in general, p53 expression appeared to correlate inversely with lymphocyte proliferation measured by MI. Cells also were treated with arsenic (As), actinomycin-D (AcD) or ionizing radiation. In two of the samples, p53 was not observed after As of AcD exposure and only low levels of p53 were observed after ionizing radiation, even when treated with 2 and 4 Gy. To find if these low levels were related to a faster degradation of the protein, we treated cultures with a proteasomal inhibitor (MG132). MG132 treatment enabled p53 induction in response to As and AcD treatment in cultures which did not show any response in the absence of MG132. Balance of induction / degradation of p53 in lymphocytes could be of relevance in the understanding of individual susceptibility to xenobiotics.",
Arsenic,2149338,Determination of mineral contents of Digitalis purpurea L. and Digitalis lanata Ehrh Abstract: ,
Arsenic,619730,"Intra-individual variability in toenail arsenic concentrations in a Michigan population, USA Abstract: Arsenic concentration in toenail clippings is used as a biomarker of exposure in epidemiological studies, often under the assumption that a single measurement represents long-term exposure. For this assumption to hold, the measured arsenic concentrations must be stable over time, yet temporal variability has not been adequately assessed. This study aims to evaluate temporal variability in multiple toenail samples collected from a population exposed to drinking water arsenic levels <100 ÃŽÂ¼g/l. Our objectives are to investigate factors responsible for biomarker variability and to assess the suitability of single versus multiple measurements for determining exposure in epidemiological studies. Multiple toenail and drinking water samples were collected from 254 participants enrolled in a caseÃ¢â‚¬â€œcontrol study of arsenic exposure and bladder cancer in Michigan, USA; participants also answered questions on water consumption. Toenail samples collected an average of 14 months apart were positively correlated, although a substantial amount of variability was detected (r=0.43, P<0.0001, n=236). Arsenic concentration in drinking water was stable and small changes in drinking water arsenic concentration did not explain variability in toenail arsenic concentration. Change in drinking water consumption, however, was significant in predicting differences in toenail arsenic concentration. Stronger correlations between drinking water arsenic concentration and intake and toenail arsenic concentration were observed when two toenail samples were averaged, suggesting that multiple measurements may more accurately reflect exposure. When exposure was categorized into tertiles and other pre-determined categories, 25Ã¢â‚¬â€œ40% of exposures were differentially classified. Only a small percentage (<4%), however, were classified as having low exposure using a single measurement and high exposure when an average of two measurements was used. These results suggest that the use of... [ABSTRACT FROM AUTHOR] Copyright of Journal of Exposure Science & Environmental Epidemiology is the property of Nature Publishing Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,2149150,"Assessing arsenic intake from groundwater and rice by residents in Prey Veng province, Cambodia Abstract: We investigated total daily intake of As by residents in Prey Veng province in the Mekong River basin of Cambodia. Groundwater (n = 11), rice (n = 11) and fingernail (n = 23) samples were randomly collected from the households and analyzed for total As by inductively coupled plasma mass spectrometry. Calculation indicated that daily dose of inorganic As was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL0.5 equals to 3.0 ?g d(-1) kg(-1)body wt.). Moreover, positive correlation between As in fingernail and daily dose of As from groundwater and rice and total daily dose of As were found. These results suggest that the Prey Veng residents are exposed to As in groundwater. As in rice is an additional source which is attributable to high As accumulation in human bodies in the Mekong River basin of Cambodia.",
Arsenic,1240274,"Variation in soft tissue chemistry among scyphozoan and cubozoan jellyfishes from the Great Barrier Reef, Australia Abstract: Bioaccumulation of trace elements in jellyfish has so far received little attention, despite their being prey for many animals from multiple trophic levels and targeted by commercial jellyfish fisheries. Scyphozoan and cubozoan jellyfish were collected over a three year period from across-shelf and along the northern and central Great Barrier Reef, Australia. To test the hypotheses that jellyfishes were able to accumulate elements above ambient background levels, and if there were spatial or temporal variations among species, soft tissue concentrations of 14 trace elements were compared with ambient seawater concentrations. Most elements, including aluminium, arsenic, barium, cadmium, chromium, copper, iron, manganese and zinc were measured at concentrations above ambient seawater levels indicating bioaccumulative capacity. Results showed some regulation of lithium in Cassiopea sp., Cyanea sp. and Mastigias sp., while calcium, magnesium and strontium reflected ambient conditions for all species. Accumulation varied significantly among species and sampling locations. For Mastigias sp. and Netrostoma sp., tissue concentrations of Al, As, Cu, Fe and Zn decreased with distance from the mainland. The hypothesis that jellyfishes are capable of accumulating trace elements was accepted, and their use as biomonitors should be investigated further.",
Arsenic,1350492,"Effect of vitamin E on sperm parameters and DNA integrity in sodium arsenite-treated rats Abstract: BACKGROUND: Arsenic as an environmental toxicant is able to exert malformations in male reproductive system by inducing oxidative stress. Vitamin E (Vit.E) is known as antioxidant vitamin. OBJECTIVE: The aim of this study was to investigate the harmful effects of sodium arsenite on sperm parameters and the antioxidant effects of Vit.E on sperm anomalies in sodium arsenite treated rats. MATERIALS AND METHODS: Adult male rats were divided into 4 groups: control, sodium arsenite (8 mg/kg/day), Vit.E (100 mg/kg/day) and sodium arsenite+Vit.E. Oral treatments were performed till 8 weeks. Body and left testis weight were recorded and then left caudal epididymis was cut in Ham's F10. Released spermatozoa were used to analyze number, motility, viability and abnormalities of the sperm. Sperm chromatin quality was assessed by nuclear staining using acridine orange and aniline blue. RESULTS: Body and testis weight showed no significant change in 4 groups (p>0.05). A significant decrease in the number, motility, viability and normal sperm morphology was found in sodium arsenite-treated rats compared to the control (p<0.001). Sodium arsenite had no effect on sperm DNA integrity and histon-protamine replacement (p>0.05). In sodium arsenite+Vit.E group, Vit.E could significantly compensate the harmful effects of sodium arsenite on sperm number, motility, viability and morphology compared to sodium arsenite group. In addition, sperm viability and motility was significantly increased in rats treated with Vit.E alone compared to the control and sodium arsenite+Vit.E group. CONCLUSION: Vitamin E could compensate the adverse effects of sodium arsenite on sperm parameters in adult rats. The aim of this study was to investigate the harmful effects of sodium arsenite on sperm parameters and the antioxidant effects of Vit.E on sperm anomalies in sodium arsenite treated rats.",
Arsenic,1251255,"Low-level arsenite activates the transcription of genes involved in adipose differentiation Abstract: In this study we analyzed gene expression in 3T3-F442A pre-adipocyte cells that differentiate in the presence of micro-molar arsenate concentration. Two concentrations of arsenite (As2O3, 0.25 micromol/L and 0.5 micromol/L) were applied for three days with and without insulin (170 nmol/L) and gene expressions were evaluated by quantitative RT-PCR. The genes included genes of oxidative-stress responses: heme-oxygenase-1 (HO1) and the hypoxia inducible factor 1a (HIF1alpha), genes of cell-cycle: c-jun and Kruppel like factor 5 (KLF5), and genes that play important roles in adipose determination: a peroxisome proliferator-activated receptor (PPARgamma) and a CCAAT/ enhancer binding protein (C/EBPalpha). Arsenite induced the expression of HO1, HIF1alpha, KLF5, PPARgamma and C/EBPalpha. These results suggest that under condition of oxidative stress arsenite induces genes that are required for adipose differentiation.",
Arsenic,1347457,"Necessity of normalization to aluminum to assess the contamination by heavy metals and arsenic in sediments near Haiphong Harbor, Vietnam Abstract: ",
Arsenic,1033751,"Quercetin, a bioflavonoid, inhibits the increase of human multidrug resistance gene (MDR1) expression caused by arsenite Abstract: Expression of the MDR1 gene, which encodes P-glycoprotein, is increased under some stress conditions. We have reported that quercetin, a bioflavonoid, inhibits the expression of heat-shock proteins. We have identified the effects of quercetin on the MDR1 gene expression in the human hepatocarcinoma cells line, HepG2. The increase of P-glycoprotein synthesis and MDR1 mRNA accumulation caused by exposure to arsenite were inhibited by quercetin. The CAT assay suggested that quercetin suppressed the transcriptional activation of the MDR1 gene after exposure to arsenite. Although many drugs that prevent the P-glycoprotein function have been reported, this is the first report to describe the inhibition of MDR1 expression by a reagent.",
Arsenic,1346446,"Examination of the expression of the heat shock protein gene, hsp110, in Xenopus laevis cultured cells and embryos Abstract: Eukaryotic organisms respond to various stresses with the synthesis of heat shock proteins (HSPs). HSP110 is a large molecular mass HSP that is part of the HSP70/DnaK superfamily. In this study, we have examined, for the first time, the expression of the hsp110 gene in Xenopus laevis cultured cells and embryos. Sequence analysis revealed that the protein encoded by the hsp110 cDNA exhibited 74% identity with its counterparts in mammals and only 27-29% with members of the Xenopus HSP70 family. Hsp110 mRNA and/or protein was detected constitutively in A6 kidney epithelial cells and was inducible by heat shock, sodium arsenite, and cadmium chloride. However, treatment with ethanol or copper sulfate had no detectable effect on hsp110 mRNA levels. Similar results were obtained for hsp70 mRNA except that it was inducible with ethanol. In Xenopus embryos, hsp110 mRNA was present constitutively during development. Heat shock-inducible accumulation of hsp110 mRNA occurred only after the midblastula stage. Whole mount in situ hybridization analysis revealed that hsp110 mRNA accumulation in control and heat shocked embryos was enriched in selected tissues. These studies demonstrate that Xenopus hsp110 gene expression is constitutive and stress inducible in cultured cells and developmentally- and tissue specifically-regulated during early embryogenesis.",
Arsenic,1365968,"c-fos induction by stress can be mediated by the SRE Abstract: The proto-oncogene c-fos is important in cell growth, differentiation and development. Several promoter elements have been identified as mediators for the induction of c-fos by serum, tumor promoting agents, epidermal growth factor and other stimuli. Stressors, including heat shock, arsenite and cadmium can induce c-fos transcription, but a heat shock element in the c-fos promoter has not been described. In this report we show that the induction of c-fos by heat shock, arsenite and cadmium can be mediated by the serum response element. Furthermore we show that casein kinase II, which has been proposed to be involved in serum induction via the serum response element, may also be involved in heat shock, arsenite and cadmium induction of c-fos.",
Arsenic,2088476,"Differential Patterns of Accumulation and Retention of Dietary Trace Elements Associated With Coal Ash During Larval Development and Metamorphosis of an Amphibian Abstract: We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at &quot;low&quot; and &quot;high&quot; concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements.",
Arsenic,1453805,"Arsenic trioxide regulates the production and activities of matrix metalloproteinases-1, -2, and -9 in fibroblasts and THP-1 Abstract: <strong>BACKGROUND: </strong>The elevated matrix metalloproteinase (MMP) activity is an important cause of chronic wound healing failure. Arsenolite, whose main component is arsenic trioxide (As2O3), is a common traditional Chinese medicine wildly used in treating chronic wounds; it can remove necrotic tissue and promote tissue regeneration. This research was designed to evaluate the effects of As2O3 on production and activities of MMP-1, MMP-2 and MMP-9, and on regulation of its signal transduction pathway in human skin fibroblasts (HSFb) and human monocyte line (THP-1 cells) that were in an inflammatory state.<br /><br /><strong>METHODS: </strong>We established three cell models; HSFb activated by TNF-?, THP-1 cells activated by phorbol 12-myristate 13-acetate (PMA) and an HSFb-THP-1 co-culture system. Three cell models was cultured with As2O3 for 24 hours. The levels of MMP-1, MMP-2, MMP-9, TNF-? and IL-1? in the cell culture supernatants were assayed by ELISA. The mRNA expressions of MMP-1, MMP-2 and MMP-9 were determined by RT-PCR. The activities of MMP-2 and MMP-9 were tested by Gelatin zymography assays. The phosphorylation levels of ERK1/2 and p38MAPK were assayed by Western blotting.<br /><br /><strong>RESULTS: </strong>As2O3 inhibited the expression of MMP-1, MMP-2 and MMP-9 mRNA, the secretion and activity of MMP-1, MMP-2 and MMP-9 in HSFb and THP-1 cells in the inflammatory state (P &lt; 0.05 and P &lt; 0.01 respectively). It also inhibited the secretion of TNF-? and IL-1? in THP-1 cells and in the co-culture system (P &lt; 0.05 and P &lt; 0.01, respectively). It also decreased the phosphorylation of ERK1/2 and p38 MAPK in HSFb and THP-1 cells (P &lt; 0.05 and P &lt; 0.01, respectively).<br /><br /><strong>CONCLUSIONS: </strong>As2O3, as a main component of arsenolite, can inhibit the production of MMPs by HSFb and THP-1 cells in an inflammatory state through inhibiting the release of inflammatory factors and the activation of the MAPK cascade pathway. This may be a possible mechanism for arsenolite healing chronic wounds.",
Arsenic,1026379,"ATM/ATR-related checkpoint signals mediate arsenite-induced G2/M arrest in primary aortic endothelial cells Abstract: Epidemiological studies have demonstrated a high association of inorganic arsenic exposure with vascular disease. Our recent in vitro studies have linked this vascular damage to vascular endothelial dysfunction induced by arsenic exposure. However, cell-cycle arrest induced by arsenic and its involvement in vascular dysfunction remain to be clarified. In this study, we employed primary porcine aortic endothelial cells to investigate regulatory mechanisms of G2/M phase arrest induced by arsenite. Our study revealed that lower concentrations of arsenite (1 and 3 microM) increased cell proliferation, whereas higher concentrations of arsenite (10, 20, and 30 microM) inhibited cell proliferation together with correlated increases in G2/M phase arrest. We found that this arsenite-induced G2/M phase arrest was accompanied by accumulation and/or phosphorylation of checkpoint-related molecules, including p53, Cdc25B, Cdc25C, and securin. Inhibition of activations of these checkpoint-related molecules by caffeine significantly attenuated the 30-microM arsenite-induced G2/M phase arrest by 93%. Our data suggest that the DNA damage responsive kinases ATM (ataxia-telangiectasia mutated) and ATR (ATM and Rad3-related) play critical roles in arsenite-induced G2/M phase arrest in aortic endothelial cells possibly via regulation of checkpoint-related signaling molecules including p53, Cdc25B, Cdc25C, and securin.",
Arsenic,1027696,"An insect model for assessing oxidative stress related to arsenic toxicity Abstract: The potential usefulness of an insect model to evaluate oxidative stress induced by environmental pollutants was examined with trivalent arsenic (As3+, NaAsO2) and pentavalent arsenic (As5+, Na2HAsO4) in adult female house flies, Musca domestica, and fourth-instar cabbage loopers, Trichoplusia ni. M. domestica was highly susceptible to both forms of arsenic following 48 h exposure in the drinking water with LC50s of 0.008 and 0.011% w/v for As3+ and As5+, respectively. T. ni larvae were susceptible to dietary As3+ with an LC50 of 0.032% w/w but seem to tolerate As5+ well with an LC50 of 0.794% concentration after 48 h exposure. The minimally acute LC5 dose of both As3+ and As5+ varied considerably but averaged 0.005% for both insects. The potential of both valencies of arsenic for inducing oxidative stress in the insects exposed ad libitum to approximately LC5 levels was assessed. The parameters examined were the alterations of the antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST), the peroxidase activity of glutathione transferase (GSTPX), and glutathione reductase (GR), and increases in lipid peroxidation and protein oxidation. SOD (1.3-fold), GST (1.6-fold), and GR (1.5-fold) were induced by As3+ in M. domestica but CAT and GSTPX were not affected. As5+ had no effect on M. domestica. In T. ni, the antioxidant enzyme activities were not affected by As3+ except for SOD which was suppressed by 29.4% and GST which was induced by 1.4-fold. As5+ had no effect except the suppression of SOD by 41.2%. Lipid peroxidation and protein oxidation, which represent stronger indices of oxidative stress, were elevated in both insects by up to 2.9-fold. However, based on the antioxidant enzyme response to the arsenic anions, the mode of action of arsenic induced oxidative stress may differ between the two insects. Until this aspect is further clarified, evidence at this time favors the prospect of As3+ as a pro-oxidant, especially for M. domestica.",
Arsenic,711015,"Prenatal and early life arsenic exposure induced oxidative damage and altered activities and mRNA expressions of neurotransmitter metabolic enzymes in offspring rat brain Abstract: To better understand the effect of arsenic on central nervous system by prenatal and early life exposure, the oxidative stress and neurotransmitter metabolic enzymes were determined in offspring rats' brain cortex and hippocampus. Forty-eight pregnant rats were randomly divided into four groups, each group was given free access to drinking water that contained 0, 10, 50, and 100 mg/L NaAsO(2) from gestation day 6 (GD 6) until postnatal day 42 (PND 42). Once pups were weaned, they started to drink the same arsenic (As)-containing water as the dams. The level of malondialdehyde in 100 mg/L As-exposed pup's brain on PND 0 and cortex on PND 28 and 42 were significantly higher than in the control group (p < 0.05). Reduced glutathione (GSH) levels showed a clear decreasing trend in pup's cortex and hippocampus on PND 42. Activity of acetylcholinesterase was significantly higher in 100 mg/L As-exposed pup's hippocampus than in control group on PND 28 and 42. mRNA expression of glutamate decarboxylase (GAD(65) and GAD(67)) in 100 mg/L As-exposed pup's cortex or hippocampus on PND 28 and 42 were significantly higher than in control (p < 0.05). These alterations in the neurotransmitters and reduced antioxidant defence may lead to neurobehavioral and learning and memory changes in offspring rats.",
Arsenic,734982,Lung cancer mortality in arsenic-exposed workers from a cadmium recovery plant Abstract: BACKGROUND: There is evidence that arsenic is a late-stage human lung carcinogen. AIMS: To investigate lung cancer risks in a cohort of cadmium recovery workers in relation to period from ceasing exposure to arsenic. METHODS: The mortality experience (1940-2001) of a cohort of 625 male workers from a US cadmium recovery plant was compared with expectations based on US national mortality rates. RESULTS: There was a statistically significant (P < 0.05) negative trend in lung cancer standardized mortality ratios in relation to period from ceasing arsenic exposure. CONCLUSIONS: The findings are consistent with the hypothesis that arsenic is a late-stage human carcinogen.,
Arsenic,1358747,"Tissue distribution and subcellular binding of arsenic in marmoset monkeys after injection of arsenic-74-labeled-arsenite Abstract: HEEP COPYRIGHT: BIOL ABS. The distribution and retention of As in marmoset monkeys, given 74As-arsenite (0.4 mg As/kg body wt) i.p., were studied by whole-body autoradiography and determination of 74As-levels in tissues and excreta. Only ? 30% of the dose was eliminated over 4 days, mainly via the kidneys. All As in urine and tissues was in an inorganic form. Tissues with highest accumulation 4 days after dosing were liver (? 20% of the dose), squamous epithelium of oral cavity and esophagus, kidney cortex, skin, testes (mainly tubuli seminiferi) and intestinal wall. The major part of the As in these tissues was associated with cellular organelles. In the liver ? 50% of the As was strongly bound to the rough microsomal membranes. In the soluble extract of tissues, As was mainly associated with macromolecular constituents. The long retention time and tight binding of As was explained by the fact that no biotransformation into methylated As occurred, in contrast to all other species studied so far.",
Arsenic,1022011,"Arsenic, cadmium and neuron specific enolase (ENO2, ?-enolase) expression in breast cancer Abstract: <strong>UNLABELLED: </strong>ABSTRACT:<br /><br /><strong>BACKGROUND: </strong>Neuron specific enolase (ENO2, ?-enolase) has been used as a biomarker to help identify neuroendocrine differentiation in breast cancer. The goal of the present study was to determine if ENO2 expression in the breast epithelial cell is influenced by the environmental pollutants, arsenite and cadmium. Acute and chronic exposure of MCF-10A cells to As+3 and Cd+2 sufficient to allow colony formation in soft agar, was used to determine if ENO2 expression was altered by these pollutants.<br /><br /><strong>RESULTS: </strong>It was shown that both As+3 and Cd+2 exposure caused significant increases in ENO2 expression under conditions of both acute and chronic exposure. In contrast, ENO1, the major glycolytic enolase in non-muscle and neuronal cells, was largely unaffected by exposure to either As+3 or Cd+2. Localization studies showed that ENO2 in the MCF-10A cells transformed by As+3 or Cd+2 had both a cytoplasmic and nuclear localization. In contrast, ENO1 was localized to the cytoplasm. ENO2 localized to the cytoplasm was found to co-localized with ENO1.<br /><br /><strong>CONCLUSION: </strong>The results are the first to show that ENO2 expression in breast epithelial cells is induced by acute and chronic exposure to As+3 or Cd+2. The findings also suggest a possible link between As+3 and Cd+2 exposure and neuroendocrine differentiation in tumors. Overall, the results suggest that ENO2 might be developed as a biomarker indicating acute and/or chronic environmental exposure of the breast epithelial cell to As+3 and Cd+2.",
Arsenic,2215756,"Amino acid assisted templating synthesis of hierarchical zeolitic imidazolate framework-8 for efficient arsenate removal Abstract: We report the strategy of using the cationic surfactant cetyltrimethylammonium bromide (CTAB) and amino acid l-histidine (His) as co-templates to produce hierarchical ZIF-8 in an aqueous system at room temperature. The hierarchical ZIF-8 had both meso- and microporous structure, resulting in a high mesopore volume as well as specific surface area which can be controlled by the synthesis conditions. We put forward the hypothesis for the formation of a mesoporous structure and the enhancement of the porosity of ZIF-8 that the histidine plays a key role on the stabilization of CTAB micelles and avoiding the production of unexpected by-products therefore promotes the fabrication of pure phase ZIF-8 containing the mesopores interconnected with micropores. The prepared hierarchical ZIF-8 exhibited an excellent performance as a new kind of porous absorbent for efficient removal of the toxic arsenate.",
Arsenic,1356890,"Further Studies On Aberrant Gene Expression In Arsenic-Induced Malignant Transformation Of Liver Epithelial Cells Abstract: Inorganic arsenic induces liver tumors in humans and rodents. In prior research we found chronic exposure (>18 wk) of rat liver epithelial TRL1215 cells to low level arsenite (500 nM) induces malignant transformation. Initial microarray studies revealed changes in gene expression in these chronic arsenic exposed (CAsE) cells that warrant further study. Real-time RT-PCR showed large increases in CAsE cell stress-response genes like glutathione S-transferase-pi (GST-pi, 3-fold), heme oxygenase- 1 (4-fold), superoxide dismutase-1 (5-fold) and metallothionein-1 (MT-1; 4- fold) compared to control. The positive cell-cycle regulatory genes cyclin D1 (10- fold) and PCNA (3-fold) were overexpressed in CAsE cells, while negative regulatory genes p21 (30% of control) and p16 (1%) were markedly depressed. In CAsE cells c-jun, c-met, c-myc,Wilms tumor protein-1 (WT-1) and alpha-fetoprotein (AFP) expression increased from 3 to 13-fold, while expression of insulin-like growth factor II (IGF-II) and fibroblast growth factor (FGF) were abolished. Western-blot analysis confirmed increases in GST-pi, WT-1, AFP and decreases in p16 and p21 protein. MT overexpression was not due to DNA methylation as bisulfite sequencing showed the MT-1 promoter region was slightly more methylated in CAsE cells than controls. Treatment of CAsE cells with the DNA demethylating agent 5-aza-deoxycytidine (Aza; 2.5 ?M, 72 hrs) greatly increased MT-1 (19- fold) compared to control cells (5-fold), indicating CAsE cells are more sensitive to DNA demethylation stress. Conversely, Aza did not restore expression of p16, IGFII, or FGF to control levels in CAsE cells, indicating suppression was due to factors other than DNA methylation changes. Thus, an intricate variety of gene expression changes occur in arsenic-induced malignant transformation, including oncogene activation and increased and decreased expression of genes critical to growth regulation.",
Arsenic,710950,"Impact of early developmental arsenic exposure on promotor CpG-island methylation of genes involved in neuronal plasticity Abstract: Epigenetic mechanisms are crucial to regulate the expression of different genes required for neuronal plasticity. Neurotoxic substances such as arsenic, which induces cognitive deficits in exposed children before any other manifestation of toxicity, could interfere with the epigenetic modulation of neuronal gene expression required for learning and memory. This study assessed in Wistar rats the effects that developmental arsenic exposure had on DNA methylation patterns in hippocampus and frontal cortex. Animals were exposed to arsenic in drinking water (3 and 36ppm) from gestation until 4 months of age, and DNA methylation in brain cells was determined by flow cytometry, immunohistochemistry and methylation-specific polymerase chain reaction (PCR) of the promoter regions of reelin (RELN) and protein phosphatase 1 (PP1) at 1, 2, 3 and 4 months of age. Immunoreactivity to 5 methyl-cytosine was significantly higher in the cortex and hippocampus of exposed animals compared to controls at 1 month, and DNA hypomethylation was observed the following months in the cortex at high arsenic exposure. Furthermore, we observed a significant increase in the non-methylated form of PP1 gene promoter at 2 and 3 months of age, either in cortex or hippocampus. In order to determine whether this exposure level is associated with memory deficits, a behavioral test was performed at the same age points, revealing progressive and dose-dependent deficits of fear memory. Our results demonstrate alterations of the methylation pattern of genes involved in neuronal plasticity in an animal model of memory deficit associated with arsenic exposure.",
Arsenic,1508667,"Molybdenum blue spectrophotometry for trace arsenic in ground water using a soluble membrane filter and calcium carbonate column Abstract: An improved molybdenum blue spectrophotometry using a soluble membrane filter and CaCO(3)-column was proposed for determining arsenic in drinking water supplied from ground water in the presence of phosphate. A 100 mL sample solution containing 0.5 - 10 ?g arsenic was passed through a CaCO(3)-column to remove phosphate, arsenate (As(V)). Arsenite (As(III)) which was not retained on the column was oxidized to As(V). As(V) was converted into a heteropolymolybdenum blue anion. The blue anion was collected on a membrane filter as an ion-associate with n-dodecyltrimethylammonium ion by filtration. The filter was dissolved in 2 mL of 2-methoxyethanol. The absorbance of the solution was measured at 810 nm against a reagent blank. Total inorganic arsenic was determined by reducing As(V) to As(III) before the column treatment. The RSDs for 10 ?g L(-1) of As(III) and As(V) were 2.9%. Phosphate 0.2 mg L(-1) (as P) and iron 0.1 mg L(-1) did not interfere with the determination of 10 ?g L(-1) arsenic. The proposed method was successfully applied to ground waters.",
Arsenic,1353957,"Particle-Induced X-ray Emission Analysis of Elements in Plasma from Wild and Captive Sea Turtles (Eretmochelys imbricata, Chelonia mydas, and Caretta caretta) in Okinawa, Japan Abstract: The aim of this study was to evaluate the reliability of direct determination of trace and major element concentrations in plasma samples from wild (six hawksbill, nine green, and nine loggerhead) and captive sea turtles (25 howksbill, five green, and three loggerhead) in Okinawa, Japan. The particle induced X-ray emission method allowed detection of 23 trace and major elements (Al, As, Br, Ca, Cl, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Ni, P, Pb, S, Se, Si, Sr, Ti, Y, and Zn). The wild sea turtles were found to have high concentrations of As and Pb in plasma compared with captive, but there were no significant changes in the Al and Hg concentrations. Loggerhead sea turtles were found to have significantly higher accumulation of As and Pb in plasma in comparison to other species. These findings may be useful when adjusting environmental and species-related factors in severely polluted marine ecosystems. Our results indicate that measuring the plasma As and Pb concentrations in wild sea turtles might be of help to assess the level of pollution in marine ecosystems, keeping in mind that loggerhead sea turtles had been shown to have higher levels of As and Pb in plasma.",
Arsenic,1021453,"Evidence of Bioactivation of Halomethanes and its Relation to Oxidative Stress Response in Chirostoma riojai, an Endangered Fish from a Polluted Lake in Mexico Abstract: Halomethanes (HMs) are produced autochthonously in water bodies through the action of ultraviolet light in the presence of HM precursors, such as dissolved organic carbon and halogens. In mammals, toxic effects induced by HMs are diverse and include oxidative stress, which is also induced by divalent and polyvalent metals; however, in fish little information is available on HM metabolism and its possible consequences at the population level. In the present study, high CYP 2E1 and GST theta-like activities were found in viscera of the Toluca silverside Chirostoma riojai from Lake Zumpango (LZ; central Mexico). Formaldehyde, one of the HM metabolites, was correlated with CYP 2E1 activity and also induced lipid peroxidation in viscera. Hepatic CYP 2E1 activity was correlated with GST theta-like activity, suggesting the coupling of both pathways of HM bioactivation and its consequent oxidative damage. Sediment metals, among others, were also responsible for oxidative stress, particularly iron, lead, arsenic and manganese. However, under normal environmental conditions, the antioxidant enzymes of this species sustain catalysis adapted to oxidative stress. Findings suggest that this fish species apparently has mechanisms of adaptation and recovery that enable it to confront toxic agents of natural origin, such as metals and other substances formed through natural processes, e.g., HMs. This has allowed C. riojai to colonize LZ despite the high sensitivity of this species to xenobiotics of anthropogenic origin.",
Arsenic,2088517,"Oxidative DNA damage and repair in children exposed to low levels of arsenic in utero and during early childhood: Application of salivary and urinary biomarkers Abstract: The present study aimed to assess arsenic exposure and its effect on oxidative DNA damage and repair in young children exposed in utero and continued to live in arsenic-contaminated areas. To address the need for biological specimens that can be acquired with minimal discomfort to children, we used non-invasive urinary and salivary-based assays for assessing arsenic exposure and early biological effects that have potentially serious health implications. Levels of arsenic in nails showed the greatest magnitude of difference between exposed and control groups, followed by arsenic concentrations in saliva and urine. Arsenic levels in saliva showed significant positive correlations with other biomarkers of arsenic exposure, including arsenic accumulation in nails (r=0.56, P&lt;0.001) and arsenic concentration in urine (r=0.50, P&lt;0.05). Exposed children had a significant reduction in arsenic methylation capacity indicated by decreased primary methylation index and secondary methylation index in both urine and saliva samples. Levels of salivary 8-OHdG in exposed children were significantly higher (~4-fold, P&lt;0.01), whereas levels of urinary 8-OHdG excretion and salivary hOGG1 expression were significantly lower in exposed children (~3-fold, P&lt;0.05), suggesting a defect in hOGG1 that resulted in ineffective cleavage of 8-OHdG. Multiple regression analysis results showed that levels of inorganic arsenic (iAs) in saliva and urine had a significant positive association with salivary 8-OHdG and a significant negative association with salivary hOGG1 expression.",
Arsenic,1070417,"Effects of cadmium and arsenic on Pteris vittata under hydroponic conditions Abstract: Pteris vittata is known to hyperaccumulate arsenic, and a large number of studies on this fern species can be found in the literature aimed at evaluating its behavior when coexposed to other toxic elements. In the present study, P. vittata was treated with different concentrations of As and/or Cd in a hydroponic system, that is, under complete bioavailability of the elements, with the objective of investigating the effects of these two elements and their interactions. The response of the plant was evaluated by measuring As, Cd, P, and Ca concentrations in different parts of the plant. Moreover, the symptoms of phytotoxicity were assessed in terms of biomass reduction and loss of photosynthetic efficiency related to necrosis of pinnae. The concentrations of As and Cd measured in the fronds and the root system were significantly dependent on the treatment, whereas P and Ca concentrations were not affected. Interaction effects between As and Cd were observed, with maximum toxicity symptoms after treatment with both elements. This could affect the potential use of this fern for phytoremediation. Although As treatment produced a significant effect on leaves (e.g., chlorosis and necrosis), Cd treatment produced a stronger negative impact on plant health, reducing significantly the biomass and photosynthetic efficiency. Environ. Toxicol. Chem. © 2012 SETAC.",
Arsenic,1579280,"Sparingly-soluble phosphate rock induced significant plant growth and arsenic uptake by Pteris vittata from three contaminated soils Abstract: We evaluated the potential of As-hyperaccumulator Pteris vittata (PV) to remove As from As-contaminated soils over five harvests in 2.5 years in a field experiment. We tested the hypothesis that a P-limiting environment would enhance PV growth and As uptake owing its unique ability to take up P under As-rich environment. In Dec. 2009, PV was transplanted to three As-contaminated soils (pH of 5.5-7.2) containing 25 - 129 mg kg-1 As, which was amended with sparingly-soluble phosphate rock (PR-soil) or soluble P fertilizer (P-soil). During the 2.5-year, PV obtained sufficient P (1,882 vs. 2,225 mg kg-1) from PR-soils, attributing to its increase in root biomass (33%) and root exudation (53%) compared to P-soils. In addition, its frond biomass increased by 20% consecutively with each harvest (six month interval) from 18 to 36 g plant-1 and its frond biomass in PR-soils (52.2 g plant-1 year-1 or ~12 mt ha-1 year-1) averaged 39% more than that in P-soils. To our knowledge, this represented the largest PV frond biomass reported, demonstrating the effectiveness of PR in enhancing PV growth. In addition to biomass increase, PV in PR-soils took up ~1.5 times more As in fronds (2,540, 780, and 920 mg kg-1) than those from P-soils (1,740, 570, and 400 mg kg-1). The low available P in PR-soils induced substantial plant growth and As uptake by PV. This translated into significantly more As removal from soil, averaging 48% reduction in PR-soils and 36% in P-soils in 2.5 years. With multiple harvests and PR amendments, our results showed As removal by PV from contaminated soils was ~7 times faster than published studies.",
Arsenic,627986,"Induction of chromosomal aberrations in cultured human fibroblasts by inorganic and organic arsenic compounds and the different roles of glutathione in such induction Abstract: Clastogenic effects of a variety of arsenic compounds were examined on cultured human fibroblasts. The following compounds were tested: inorganic arsenicals (arsenite and arsenate), the major metabolites of inorganic arsenicals in human and experimental animals [methylarsonic acid (MAA), dimethylarsinic acid (DMAA) and trimethylarsine oxide (TMAO)], and water-soluble organoarsenic derivatives [2?,3?-dihydroxypropyl-5-deoxy-5-dimethylarsinoyl-?-Image -riboside (arsenosugar), arsenocholine, arsenobetaine and tetramethylarsonium iodide] found in marine organisms. Arsenic compounds induced mainly chromatid gaps and chromatid breaks. The rank order of compounds in terms of clastogenic potency was arsenite arsenate DMAA MAA TMAO. DMAA was very potent and caused chromosome pulverizations in most metaphases when present at doses higher than 7 × 10?3 M. Arsenosugar, arsenocholine, arsenobetaine and tetrametylarsonium iodide were less effective. Depletion of cellular glutathione (GSH) with Image -buthionine-SR-sulfoximine (BSO), increased the incidence of chromosomal aberrations induced by arsenite, arsenate and MAA, and markedly suppressed the clastogenic effects of DMAA. DMAA was highly clastogenic even in GSH-depleted cells when the cells were incubated with DMAA in the presence of GSH (5 and 10 mM). These results suggest that GSH might play a role in protecting cells against the clastogenic effects of arsenite, arsenate and MAA. GSH might be involved in the expression of clastogenic actions of DMAA.",
Arsenic,627669,"Molecular events associated with arsenic-induced malignant transformation of human prostatic epithelial cells: Aberrant genomic DNA methylation and K-ras oncogene activation Abstract: Numerous studies link arsenic exposure to human cancers in a variety of tissues, including the prostate. Our prior work showed that chronic arsenic exposure of the non-tumorigenic, human prostate epithelial cell line, RWPE-1, to low levels of (5 microM) sodium arsenite for 29 weeks resulted in malignant transformation and produced the tumorigenic CAsE-PE cell line. The present work focuses on the molecular events occurring during this arsenic-induced malignant transformation. Genomic DNA methylation was significantly reduced in CAsE-PE cells. A time course experiment showed that during malignant transformation DNA methyltransferase activity was markedly reduced by arsenic. However, DNA methyltransferase mRNA levels were not affected by arsenic exposure. Microarray screening showed that K-ras was highly overexpressed in CAsE-PE cells, a result further confirmed by Northern blot and Western blot analyses. Since ras activation is thought to be a critical event in prostate cancer progression, further detailed study was performed. Time course experiments also showed that increased K-ras expression preceded malignant transformation. Mutational analysis of codons 12, 13, and 61 indicated the absence of K-ras mutations. The K-ras gene can be activated by hypomethylation, but our study showed that CpG methylation in K-ras promoter region was not altered by arsenic exposure. Arsenic metabolism studies showed RWPE-1, CAsE-PE, and primary human prostate cells all had a very poor capacity for arsenic methylation. Thus, inorganic arsenic-induced transformation in human cells is associated with genomic DNA hypomethylation and K-ras overexpression. However, overexpression of K-ras occurred without mutations and through a mechanism other than promoter region hypomethylation.",
Arsenic,1348703,"STUDY OF INTERMOLECULAR INTERACTIONS IN A SYSTEM FOR EQUILIBRIUM CATALYTIC TRANSESTERIFICATION OF ESTERS .1. REACTION OF BORON, TITANIUM, AND ARSENIC BUTOXIDES WITH ESTERS ACCORDING TO IR FOURIER SPECTROSCOPIC DATA Abstract: ",
Arsenic,1519189,Review on Toxic Metal Speciation Analysis Based on Coupled Technique HPLC-ICP-MS (Environmental Aspects) Abstract: ,
Arsenic,627032,"Arsenic alters the function of the glucocorticoid receptor as a transcription factor Abstract: Chronic human exposure to nonovertly toxic doses of arsenic is associated with an increased risk of cancer. Although its carcinogenic mechanism is still unknown, arsenic does not directly cause DNA damage or mutations and is therefore thought to act principally as a co-mutagen, co-carcinogen, and/or tumor promoter. Previous studies in our laboratory demonstrated that effects of lowdose arsenic (III) (arsenite) on expression of the hormone-regulated phosphoenolpyruvate carboxykinase (PEPCK) gene were strongly associated with the glucocorticoid receptor (GR)-mediated regulatory pathway. We therefore examined specifically the effects of arsenite on the biochemical function of GR in hormone-responsive H4IIE rat hepatoma cells. Completely noncytotoxic arsenite treatments (0.3–3.3 ?M) significantly decreased dexamethasone-induced expression of transiently transfected luciferase constructs containing either an intact hormone-responsive promoter from the mammalian PEPCK gene or two tandem glucocorticoid response elements (GRE). Western blotting and confocal microscopy of a green fluorescent protein-tagged–GR fusion protein demonstrated that arsenite pretreatment did not block the normal dexamethasone-induced nuclear translocation of GR. These data indicate that nontoxic doses of arsenite can interact directly with GR complexes and selectively inhibit GR-mediated transcription, which is associated with altered nuclear function rather than a decrease in hormone-induced GR activation or nuclear translocation. Key words: arsenic, carcinogenesis, endocrine disruptor, gene regulation, glucocorticoid receptor, metal, transcription factor.",
Arsenic,1337330,"Total and inorganic arsenic in dietary supplement supplies in northern Mexico Abstract: The aim of this study was to evaluate the presence of total and inorganic arsenic in dietary supplements composed of herbal plants and seaweed, and to determine the potential toxicological risk. Total arsenic was determined by dry ashing and hydride generation atomic absorption spectrometry, and inorganic arsenic was determined by acid digestion, solvent extraction, and hydride generation atomic absorption spectrometry. Total and inorganic arsenic in the supplements ranged from 0.07 to 8.31 mg?kg(-1) dry weight and from 0.14 to 0.28 mg?kg(-1) dry weight, respectively. Daily intake of total arsenic ranged from 0.05 to 12.46 ?g?day(-1). Inorganic arsenic intake ranged from 0.21 to 0.83 ?g?day(-1), values that are below the Benchmark Dose Lower Confidence Limit recommended by the Word Health Organization. Therefore, there appears to be a low risk of adverse effects resulting from excess inorganic arsenic intake from these supplements. This is the first study conducted in Mexico that investigates total and inorganic arsenic in dietary supplements. Although the results do not suggest toxicological risk, it is nonetheless important considering the toxicity of inorganic arsenic and the increasing number consumer preferences for dietary supplements. Moreover, it is important to improve and ensure the safety of dietary supplements containing inorganic arsenic.",
Arsenic,2278225,"Molybdate reduction to molybdenum blue by an antarctic bacterium Abstract: A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo6+ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20 degrees C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo- reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20 degrees C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum- reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.",
Arsenic,1936065,"Geochemical modeling of arsenic release from a deep natural solid matrix under alternated redox conditions Abstract: Dissolved arsenic (As) concentrations detected in groundwater bodies of the Emilia-Romagna Region (Italy) exhibit values which are above the regulation limit and could be related to the natural composition of the host porous matrix. To support this hypothesis, we present the results of a geochemical modeling study reproducing the main trends of the dynamics of As, Fe, and Mn concentrations as well as redox potential and pH observed during batch tests performed under alternating redox conditions. The tests were performed on a natural matrix extracted from a deep aquifer located in the Emilia-Romagna Region (Italy). The solid phases implemented in the model were selected from the results of selective sequential extractions performed on the tested matrix. The calibrated model showed that large As concentrations have to be expected in the solution for low crystallinity phases subject to dissolution. The role of Mn oxides on As concentration dynamics appears significant in strongly reducing environments, particularly for large water-solid matrix interaction times. Modeled data evidenced that As is released firstly from the outer surface of Fe oxihydroxides minerals exhibiting large concentrations in water when persistent reducing conditions trigger the dissolution of the crystalline structure of the binding minerals. The presence of organic matter was found to strongly affect pH and redox conditions, thus influencing As mobility.",
Arsenic,1027226,"A method detection limit for potential in vivo arsenic measurements with a 50 W x-ray tube Abstract: Using a 50 W x-ray tube as the fluorescing source, an x-ray fluorescence system was designed to measure arsenic in superficial layers of tissue-simulating phantoms. The detection limit for arsenic in the phantoms at a setting of 35 kV and with 200 microm of a Mo filter was 0.40 +/- 0.06 microg As g(-1). This measurement results in an effective dose of 0.6 microSv.",
Arsenic,1453810,"Arsenic-induced biochemical and genotoxic effects and distribution in tissues of Sprague-Dawley rats Abstract: Arsenic (As) is a well documented human carcinogen. However, its mechanisms of toxic action and carcinogenic potential in animals have not been conclusive. In this research, we investigated the biochemical and genotoxic effects of As and studied its distribution in selected tissues of Sprague-Dawley rats. Four groups of six male rats, each weighing approximately 60 ± 2 g, were injected intraperitoneally, once a day for 5 days with doses of 5, 10, 15, 20 mg/kg bw of arsenic trioxide. A control group was also made of 6 animals injected with distilled water. Following anaesthetization, blood was collected and enzyme analysis was performed by spectrophotometry following standard protocols. At the end of experimentation, the animals were sacrificed, and the lung, liver, brain and kidney were collected 24 h after the fifth day treatment. Chromosome and micronuclei preparation was obtained from bone marrow cells. Arsenic exposure significantly increased (p&lt;0.05) the activities of plasma alanine aminotransferase-glutamate pyruvate transaminase (ALT/GPT), and aspartate aminotransferase-glutamate oxaloacetate transaminase (AST/GOT), as well as the number of structural chromosomal aberrations (SCA) and frequency of micronuclei (MN) in the bone marrow cells. In contrast, the mitotic index in these cells was significantly reduced (p&lt;0.05). These findings indicate that aminotransferases are candidate biomarkers for arsenic-induced hepatotoxicity. Our results also demonstrate that As has a strong genotoxic potential, as measured by the bone marrow SCA and MN tests in Sprague-Dawley rats. Total arsenic concentrations in tissues were measured by inductively coupled plasma mass spectrometry (ICP-MS). A dynamic reaction cell (DRC) with hydrogen gas was used to eliminate the ArCl interference at mass 75, in the measurement of total As. Total As doses in tissues tended to correlate with specific exposure levels.",
Arsenic,1677586,"Midterm results of endovascular abdominal aortic aneurysm repair: comparison of instruction-for-use (IFU) cases and non-IFU cases Abstract: PURPOSE: To investigate the midterm results of abdominal aortic aneurysm repair (EVAR) and compare the endoleak (EL) and abdominal aortic aneurysm (AAA) prognoses between instruction-for-use (IFU) patients and non-IFU patients. MATERIALS AND METHODS: Of 124 patients (104 men, 20 women; mean age 76.2 years; age range 58-93 years) with AAA who underwent EVAR with the Zenith (68 patients) or Excluder device (56) and were analyzed, 86 were IFU and 38 non-IFU. RESULTS: The mean absorbed dose of radiation exposure was 1907 mGy in the IFU group and 2283 mGy in the non-IFU group (p = 0.013). Thirty-five patients experienced EL: 8 (6.5 %) type I and 27 (21.8 %) type II. Type I ELs were observed in 3 patients in the IFU group (3.5 %) and 5 patients in the non-IFU group (13.2 %). Of the 14 patients with AAA diameter expansion of ?5 mm, 6 (6/86, 7.0 %) belonged to the IFU group and 8 (8/38, 21.1 %) to the non-IFU group (p = 0.027). CONCLUSION: The frequency of AAA expansion ?5 mm was higher in non-IFU patients than in IFU patients. Therefore, careful follow-up is necessary for non-IFU patients rather than IFU patients.",
Arsenic,1378381,"Arsenic-Induced Gene Expression Changes in the Neural Tube of Folate Transport Defective Mouse Embryos and #150; Microarray Analysis Abstract: Inorganic arsenic occurs naturally in the environment and as an industrial contaminant. Epidemiological studies conducted in heavily polluted areas provide evidence that arsenic exposure causes adverse health effects. Arsenic is a potent human carcinogen and a suspected teratogen, although data from epidemiological studies remains inconclusive. Experiments in laboratory animals have consistently shown arsenic to be teratogenic, primarily inducing exencephaly. We have shown that a low folate diet and genetic inactivation of the folate binding protein 2 (Folbp2) gene both separately, and synergistically, exacerbate arsenic and #146;s induction of NTDs. In order to better understand this phenomenon, we performed microarray analysis of gene expression in the neural tube of Folbp2-/- embryos exposed to arsenic in utero. Pregnant Folbp2-/- dams were treated with 40 mg/kg sodium arsenate on E 7:12 and E 8:12. Embryos from treated and control dams were collected at E 8:15, E 9:00 and E 9:12. Anterior neural tubes were dissected from the embryos and total RNA was extracted. After in vitro transcription and amplification, antisense RNA was biotinstreptavidin labeled and hybridized to the CodeLink UniSet 10K Bioarray. No less than 6 embryonic neural tubes (3 controls and 3 arsenic treated) were used to evaluate the gene expression at each of the three selected time-points. Microarray slides were scanned, features extracted and expression values for 10500 genes were generated. After extensive statistical analysis, we identified 233 differentially expressed genes: 112 downregulated genes, and 121 upregulated genes. Ontological enrichment analysis of all differentially expressed genes identified numerous ontological groups displaying significant enrichment (P<0.005). These genes were classified into three groups: the I-kappaB kinase/NF-kappaB cascade, oxidative phosphorylation, and eukaryotic translocation elongation factor 1 complex. Specifically, the down regulation of oxidative phosphorylation genes may lead to decreased ATP synthesis and reactive oxygen species (ROS) production. As these ROS overwhelm the antioxidant capacity of the cell, oxidative stress ensues, presumably triggering the observed up regulation of genes from the I-kappaB kinase/NF-kappaB cascade.",
Arsenic,628798,"Genotoxic effects in C57Bl/6J mice chronically exposed to arsenate in drinking water and modulation of the effects by low-selenium diet Abstract: In C57Bl/6J mice chronically exposed to arsenate in drinking water at 50, 200, or 500 ?g As/L, genotoxic effects in bone-marrow cells using micronucleus test and in peripheral blood leukocytes using the comet assay were determined after 3, 6 or 12 mo. To assess the modulating role of selenium in development of the effects, the animals were fed a specially prepared low-selenium diet and were supplemented with sodium selenite (200 ?g Se/L) in drinking water (supplemented groups) or were without Se supplementation (nonsupplemented groups). Measurements of glutathione peroxidase activity in erythrocytes and plasma as well as selenium concentration in plasma were performed after 3, 6, and 12 mo and showed a marked decrease in values in animals in non-Se supplemented compared to Se-supplemented groups. After 3 mo of arsenic exposure in the Se-supplemented animals the level of DNA fragmentation (without Endo III and Fpg enzymes) did not differ from the control; however, increased oxidative damage of purine and pyrimidine bases was observed. In groups not supplemented with Se, an increase of DNA fragmentation was observed; however, the levels of oxidative DNA damage in these groups did not differ from the control. None of the positive effects observed in the comet assay after 3 mo was related to arsenate concentration. The levels of DNA damage after 6 and 12 mo of exposure to arsenic as well as the frequency of micronuclei after 3, 6, and 12 mo did not differ significantly between exposed and control animals, irrespective of Se supplementation status.",
Arsenic,554507,"Environmental causes of violence Abstract: Violent and anti-social behavior is usually attributed to social factors, including poverty, poor education, and family instability. There is also evidence that many forms of violent behavior are more frequent in individuals of lower IQ. The role of exposure to environmental contaminants has received little attention as a factor predisposing to violent behavior. However a number of environmental exposures are documented to result in a common pattern of neurobehavioral effects, including lowered IQ, shortened attention span, and increased frequency of antisocial behavior. This pattern is best described for children exposed to lead early in life, but a similar pattern is seen upon exposure to polychlorinated biphenyls and methyl mercury. Although not as extensively studied, similar decrements in IQ are seen upon exposure to arsenic and secondhand smoke (SHS) exposure. Prenatal and postnatal SHS exposure is also associated with increased rates of conduct disorder and attention deficit hyperactivity. Recent evidence suggests that temporal trends in rates of violent crime in many nations are consistent with earlier preschool blood lead trends, with a lag of about 20Â years. These ecologic correlations are consistent with many controlled studies suggesting that lead-exposed children suffer irreversible brain alterations that make them more likely to commit violent crimes as young adults. If this pattern is true for lead and other contaminants, the most effective way to fight crime may be to prevent exposure to these contaminants.",
Arsenic,1022135,"Arsenic-induced straighthead: an impending threat to sustainable rice production in South and South-East Asia! Abstract: Straighthead is a physiological disorder of rice (Oryza sativa L.) that results in sterile florets with distorted lemma and palea, and the panicles or heads may not form at all in extreme cases. Heads remain upright at maturity, hence the name 'straighthead'. The diseased panicles may not emerge from the flag leaf sheath when the disease is severe. Straighthead disease in rice results in poorly developed panicles and significant yield loss. Although other soil physicochemical factors involved, arsenic contamination in soil has also been reported to be closely associated with straighthead of rice. Monosodium methanearsonate has been a popular herbicide in cotton production in the USA, which has shown to cause injuries in rice that are similar to straighthead. Since toxicity of inorganic arsenic (iAs) is higher than other forms of arsenic, it may produce a more severe straighthead disorder in rice. The use of iAs-rich groundwater for irrigation, and the increase of iAs concentrations in agricultural soil in arsenic epidemic South and South-East Asia may cause a high incidence of straighthead in rice, resulting in a threat to sustainable rice production in this region.",
Arsenic,1576390,"Survey of total mercury and arsenic content in infant cereals marketed in Spain and estimated dietary intake Abstract: Due to the fact that infants and children are especially sensitive to mercury and arsenic exposure, predominantly through diet, a strict control of the most widely consumed infant foods, especially infant cereals, is of paramount importance. Levels of both total mercury and arsenic in 91 different infant cereals from ten different manufacturers in Spain were determined by flow injection adapted to cold vapor and hydride generation atomic absorption spectrometry, respectively. Cereals were assessed in terms of the different types, the predominating cereal in the formulation, the added ingredients, and whether the cereal was organically or conventionally obtained. In general, the content of toxic elements (median (Q(1); Q(3))) found in infant cereals based on conventionally obtained raw materials (n = 74, Hg: 2.11 (0.42; 4.58), As: 21.0 (9.4; 50.9) mu g Kg(-1)) was lower than in cereals produced by organic methods (n = 17, Hg: 5.48 (4.54; 7.64), As: 96.3 (87.5; 152.3) mu g Kg(-1)). Mercury content in infant cereals shows the higher values in those formulations with ingredients susceptible to particulate contamination such as gluten-free or cacao-based cereals. The highest arsenic content appears in the rice-based cereals. The mercury and the inorganic arsenic dietary intakes for infants fed on the infant cereals studied were assessed, taking into account the different stages of growth. Organic infant cereals based on cocoa showed the highest risk intakes of mercury, very close to exceeding the intake reference. Just the opposite, 95% of the organically produced infant cereals and 70% of the conventional gluten-free infant cereals showed an inadmissible risk of arsenic intake. Thus, it seems prudent to call for continued efforts in standardizing routine quality control and in reducing arsenic levels in infant cereals; in addition it is essential that relevant legislation be established and regulated by EC regarding these two toxic elements. (C) 2012 Elsevier Ltd. All rights reserved.",
Arsenic,1017399,"Risk of human exposure to arsenic and other toxic elements from geophagy: Trace element analysis of baked clay using inductively coupled plasma mass spectrometry Abstract: BACKGROUND: Geophagy or earth-eating is common amongst some Bangladeshi women, especially those who are pregnant, both in Bangladesh and in the United Kingdom. A large proportion of the population in Bangladesh is already exposed to high concentrations of arsenic (As) and other toxic elements from drinking contaminated groundwater. Additional exposure to As and other toxic elements from non-food sources has not been adequately addressed and here we present the first study to monitor As levels in baked clay (known as sikor). METHODS: Sikor samples originating from Bangladesh were digested using a microwave digester and analysed for their As, Pb, Cd, Mn, Fe and Zn levels using ICP-MS. Detailed As speciation analysis was performed using HPLC-ICP-MS. RESULTS: Of particular concern were the levels of As (3.8-13.1 mg kg(-1)), Cd (0.09-0.4 mg kg(-1)) and Pb (21-26.7 mg kg(-1)) present in the sikor samples and their possible impact on human health. Speciation analysis revealed that sikor samples contained mainly inorganic As. Modest consumption of 50 g of sikor is equivalent to ingesting 370 ?g of As and 1235 ?g of Pb per day, based on median concentration values. This level of sikor consumption exceeds the permitted maximum tolerable daily intake (PMTDI) of inorganic As by almost 2-fold. CONCLUSION: We conclude that sikor can be a significant source of As, Cd and Pb exposure for the Bangladeshi population consuming large quantities of this material. Of particular concern in this regard is geophagy practiced by pregnant women concurrently exposed to As contaminated drinking water. Future studies needs to evaluate the bioavailability of As and other elements from sikor and their impact on human health.",
Arsenic,1240273,"Influence of iron plaque and cultivars on antimony uptake by and translocation in rice (Oryza sativa L.) seedlings exposed to Sb(III) or Sb(V) Abstract: Background and Aims: Characteristically baseline levels of Sb in the environment are low, but problematic local elevation trends arise from anthropogenic activities such as mining and incineration. Arsenic (analog of Sb) accumulation by rice can be reduced by iron (Fe) plaque. A hydroponic experiment was conducted to investigate whether Fe plaque could reduce the uptake and translocation of different Sb species in different rice cultivars. Methods: After Fe plaque on rice roots was induced in solution containing 0, 0.2, 0.4, 0.7, 1.2, 2.0 mM Fe super(2+) for 24 h, seedlings were transferred into nutrient solution with 20 mu M Sb(V) or Sb(III) for 3 d. Results: About 60-80% (Sb(III) treatment) and 40-60% (Sb(V) treatment) of the total Sb accumulated in Fe plaque. There was a significant correlation between the concentrations of Sb and Fe on the root surface. A similar relationship was observed in roots and shoots. Cultivar (Jiahua 1) formed the most Fe plaque, had the highest Fe associated Sb sequestration but the lowest Sb concentration in the root interior. Conclusions: Fe plaque may act as a 'buffer' for Sb(V) and Sb(III) in the rhizosphere, and cultivars played an important role in the different species Sb uptake and translocation.",
Arsenic,1353452,Determination of arsenic in fly ash and sulphide ore by flame atomic absorption spectrometry using hydride generator Abstract: ,
Arsenic,2064287,"Arsenic, zinc, and aluminium removal from gold mine wastewater effluents and accumulation by submerged aquatic plants (Cabomba piauhyensis, Egeria densa, and Hydrilla verticillata) Abstract: The potential of three submerged aquatic plant species (Cabomba piauhyensis, Egeria densa, and Hydrilla verticillata) to be used for As, Al, and Zn phytoremediation was tested. The plants were exposed for 14 days under hydroponic conditions to mine waste water effluents in order to assess the suitability of the aquatic plants to remediate elevated multi-metals concentrations in mine waste water. The results show that the E. densa and H. verticillata are able to accumulate high amount of arsenic (95.2%) and zinc (93.7%) and resulted in a decrease of arsenic and zinc in the ambient water. On the other hand, C. piauhyensis shows remarkable aluminium accumulation in plant biomass (83.8%) compared to the other tested plants. The ability of these plants to accumulate the studied metals and survive throughout the experiment demonstrates the potential of these plants to remediate metal enriched water especially for mine drainage effluent. Among the three tested aquatic plants, H. verticillata was found to be the most applicable (84.5%) and suitable plant species to phytoremediate elevated metals and metalloid in mine related waste water.",
Arsenic,1029552,"Taurine protects rat testes against NaAsO(2)-induced oxidative stress and apoptosis via mitochondrial dependent and independent pathways Abstract: Arsenic (As) is a well known toxicity inducer. Recent investigations, however, showed that it might have some therapeutic application in cancer treatment. These dual roles of arsenic have attracted a renewed research in organ pathophysiology. In this study, we report that As administration (in the form of NaAsO(2) at a dose of 10mg/kg body weight for 2 days, orally) induces apoptosis in testicular tissue of the experimental rats by the activation of caspase-3 and reciprocal regulation of Bcl-2/Bad with the concomitant reduction of mitochondrial membrane potential and increased level of cytosolic cytochrome C. Arsenite has also been shown to induce activation of mitogen-activated protein kinases (MAPKs), Akt as well as NF-kappaB (p65) in testicular tissue. In addition, As significantly decreased testicular Delta(5)-3beta-HSD and 17beta-HSD activities and reduced the plasma testosterone level, testicular sperm count and sperm motility. Besides, arsenite exposure increased the levels of reactive oxygen species (ROS), serum TNF-alpha, As accumulation and lipid peroxidation and decreased the activities of the antioxidant enzymes and glutathione in the testicular tissue. Oral administration of taurine (at a dose of 100mg/kg body weight for 5 days) was found to be effective in counteracting As-induced oxidative stress, attenuation of testicular damages and amelioration of apoptosis in testicular tissue by controlling the reciprocal regulation of Bcl-2/Bad, phospho-ERK1/2, phospho-p38, phospho-Akt and NF-kappaB. Taurine was also found to play similar beneficial role via mitochondrial dependent pathways in As-induced testicular damages leading to apoptotic cell death.",
Arsenic,1794750,Definition of areas of probable risk to human health posed by As and Pb in soils and ground-level dusts of the surrounding area of an abandoned As-sulfide mine in the north of Portugal: part 1 Abstract: ,
Arsenic,2345710,"Stabilising metal(loid)s in soil with iron and aluminium-based products: Microbial, biochemical and plant growth impact Abstract: Four iron and aluminium-based products, including red mud (RM), hematite (Fe2O3), an iron-rich water treatment residual (Fe-WTR) and amorphous Al hydroxide (Al-OH), were evaluated for their effectiveness at stabilising As and heavy metals (i.e. Cd, Cu, Pb, Zn) in a circumneutral contaminated soil [As (2105 mg kg(-1)), Cd (18 mg kg(-1)), Cu (264 mg kg(-1)), Pb (710 mg kg(-1)), Zn (522 mg kg(-1))]. Treatment impacts on soil microbial and biochemical features (i.e. microbial biomass-C, microbial counts, 16S rRNA PCR-TTGE of culturable bacteria, dehydrogenase, urease and ?-glucosidase activity, Biolog derived parameters-AWCD and richness) as well as bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth were also assessed. After 6 months equilibration, all the amendments (application rate 3% w/w) but RM reduced labile As while only Al-OH reduced the concentration of water-soluble heavy metals. Despite the highest bioavailability of contaminants, most of the soil microbial and biochemical features monitored (i.e. microbial biomass-C, total bacterial counts, dehydrogenase activity and AWCD) were significantly higher in the RM-soil. Bean germination was completely inhibited in RM-soil while wheat growth was similar to that of the control. The Al-OH treatment was best overall, promoting microbial abundance, diversity and activity while increasing bean and wheat growth and reducing As accumulated in plant shoots. Results suggest that Al-OH is a suitable candidate for field evaluations while the use of RM in the remediation of circumneutral or subalkaline contaminated soils should be reconsidered.",
Arsenic,1597334,"Goitre and urinary iodine excretion survey in schoolchildren of Kashmir Valley Abstract: BACKGROUND: An extensive survey on schoolchildren in Kashmir Valley in 1995 showed a high prevalence of goitre, making it imperative to have a relook at our iodine status, 15 years post-iodisation. OBJECTIVE: To study the total prevalence of goitre and urinary iodine excretion (UIE) in Kashmiri schoolchildren, 15 years post-iodisation. DESIGN: A cross-sectional survey, covering 9576 schoolchildren, aged 5-15 years (5988 in 6-12 year age-group). Goitres were graded as per WHO/UNICEF/ICCIDD. UIE was measured by the arsenic acid reduction of ceric ions method, and was estimated in 208 sub-sampled children. Results were compared with that of 1995 survey. RESULTS: The overall prevalence of goitre in the present study was 3.8% (95% CI: 3.4-4.2) (5-15 year age-group), and 3.7% (95% CI: 3.2-4.2) in those aged 6-12 years. No significant difference in prevalence of goitre was observed between boys and girls overall (3.6% vs. 4.1%. P&gt;0.2), nor in the 6-12 year age-group (3.3% vs. 4.0%, P&gt;0.1). There was a significant trend of increasing prevalence of goitre with age (P, 0.005). UIE ranged from 12 to 397 ?g/g.creatinine (median, 104); 11% subjects had UIE of &lt;50 ?g/g.creatinine. Overall, prevalence of goitre was significantly lower (3.8% vs. 45.2%, P&lt;0.001) and mean UIE was significantly better (123.6±5.3 vs. 49.60±3.55 ?g/g.creatinine, P&lt;0.001), compared to that in the 1995 survey. CONCLUSION: The marked improvement in overall iodine nutrition in Kashmir Valley, one and a half decades after implementation of salt iodisation should encourage healthcare providers to make tangible efforts for implementation of iodisation programs in areas with iodine deficiency. This article is protected by copyright. All rights reserved.",
Arsenic,1033513,"Ultrastructural cytochemical analysis of intranuclear arsenic inclusions Abstract: To establish the chemical composition of the arsenic inclusion, freshly isolated preparations of inclusions and epon-embedded thin sections of inclusions were subjected to ultrastructural cytochemical analysis. Intranuclear inclusions are composed of amorphous, arsenic-containing subunits aligned linearly to form a coiled complex. Lipase, ribonuclease, deoxyribonuclease, trypsin, pepsin, protease, amylase, or ethylenediaminetetraacetic acid (EDTA) was used to digest or chelate these inclusions. Following enzymatic digestion or chelation, the electron opacity of inclusions was compared with that of control sections exposed for equal times to equivalent solutions lacking the enzymes. Exposure to amylase caused a consistent reduction in the electron opacity of thin sections of inclusions and almost complete digestion of the freshly isolated preparations of inclusions. This was indicative of the presence of a carbohydrate moiety within arsenic inclusions. Incubation of inclusions with EDTA resulted in solubilization of freshly isolated and thin-sectioned embedded material. These data indicated that the intranuclear arsenic inclusion is composed of both metallic and carbohydrate moieties, confirming earlier studies which identified arsenic within inclusions using instrumental neutron activation analysis and X-ray microprobe analysis.",
Arsenic,1367945,"Preservation of keratin expression in oral mucosa using a novel transport medium Abstract: Cellular expression of keratins (intermediate filaments) can be demonstrated by immunocytochemistry using unfixed tissue. However, for practical reasons, provision of fresh tissue to the laboratory is often difficult. Recently a fresh tissue transport medium (Patent applied for) has been developed which allows keratin immunocytochemistry to be performed up to 4 days after biopsy. In this study oral mucosal biopsies from 10 patients were hemisected, half placed in the new transport medium at 4 degrees C and the other half immediately frozen in liquid nitrogen. After 4 days frozen sections of both halves of the biopsies were stained by immunocytochemistry using various antikeratin antibodies. The morphology and staining characteristics of the two halves of the biopsies were then assessed. No significant difference could be found in either morphology or preservation of keratin expression in specimens stored in transport medium, as compared to those in liquid nitrogen. This new transport medium may offer considerable advantage for the provision of a histologic and immunocytochemical diagnostic service.",
Arsenic,1597366,"Catalase has a key role in protecting cells from the genotoxic effects of monomethylarsonous acid: A highly active metabolite of arsenic Abstract: Although it is widely known that arsenic-contaminated drinking water causes many diseases, arsenic's exact mode of action (MOA) is not fully understood. Induction of oxidative stress has been proposed as an important key event in the toxic MOA of arsenic. The authors' studies are centered on identifying a reactive species involved in the genotoxicity of arsenic using a catalase (CAT) knockout mouse model that is impaired in its ability to breakdown hydrogen peroxide (H2 O2 ). The authors assessed the induction of DNA damage using the Comet assay following exposure of mouse Cat(+/) (+) and Cat(-) (/) (-) primary splenic lymphocytes to monomethylarsonous acid (MMA(III) ) to identify the potential role of H2 O2 in mediating cellular effects of this metalloid. The results showed that the Cat(-) (/) (-) lymphocytes are more susceptible to MMA(III) than the Cat(+/) (+) lymphocytes by a small (1.5-fold) but statistically significant difference. CAT activity assays demonstrated that liver tissue has approximately three times more CAT activity than lymphocytes. Therefore, Comet assays were performed on primary Cat(+/) (+) , Cat(+/) (-) , and Cat(-) (/) (-) hepatocytes to determine if the Cat(-) (/) (-) cells were more susceptible to MMA(III) than lymphocytes. The results showed that the Cat(-) (/) (-) hepatocytes exhibit higher levels of DNA strand breakage than the Cat(+/) (+) (approximately fivefold) and Cat(+/) (-) (approximately twofold) hepatocytes exposed to MMA(III) . Electron spin resonance using 5,5-dimethyl-1-pyrroline-N-oxide as the spin-trap agent detected the generation of ·OH via MMA(III) when H2 O2 was present. These experiments suggest that CAT is involved in protecting cells against the genotoxic effects of the ·OH generated by MMA(III).",
Arsenic,1508527,"Quantitative real-time expression profiling of aquaporins-isoforms and growth response of Brassica juncea under arsenite stress Abstract: The present study analyzed the expression level of aquaporins of plasma membrane intrinsic protein (PIP) class in response to arsenite (AsIII) exposure of 100 ?M from 0.5 h to 8 days in Brassica juncea. The expression levels of most of the PIPs were down-regulated during the course of AsIII exposure. This led to decrease in total water content of plants, which in turn hampered seedling growth. The level of reactive oxygen species (superoxide radicals and hydrogen peroxide), lipid peroxidation and root oxidizability increased significantly upon exposure to AsIII as compared to that of control leading to an increase in cell death. The study proposes that the down-regulation of PIPs happened presumably to regulate AsIII levels, which, however, occurred at the cost of reduced growth, disturbed water balance and induced oxidative stress.",
Arsenic,1353145,Phosphate supply as a promoter of tolerance to arsenic in pearl millet Abstract: ,
Arsenic,2039137,"The nature of synthetic basic ferric arsenate sulfate (Fe(AsO4)(1-x)(SO4)(x)(OH)(x)) and basic ferric sulfate (FeOHSO4): Their crystallographic, molecular and electronic structure with applications in the environment and energy Abstract: In this study we investigate a new family of arsenate-bearing phases belonging to one set of structures (Basic Ferric Sulfate-BFS: monoclinic–orthorhombic FeOHSO4) that are significant as an industrial arsenic control material in the environment or a cathodic material in rechargeable Li-ion battery cells. We determine for the first time (after two decades of its known existence in the processing industry) the average crystallographic structure of Basic Ferric Arsenate Sulfate-BFAS: Fe(AsO4)1?x(SO4)x(OH)x·(1?x)H2O) that is a member of this family of phases and how it relates to its parent BFS structure. Moreover, we demonstrate how the substitution of AsO4 ? SO4 affects the crystallographic structure of these phases, the phase(s) that are formed and their material properties as environmentally stable arsenic controls or Li-ion battery cathodes.",
Arsenic,711028,"Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam Abstract: This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam. Arsenic levels in groundwater ranged from &lt;1.8 to 486 microg/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 microg/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 microg/week/kg body wt.) by FAO/WHO for 92% of the residents examined. Inorganic As and its metabolite (monomethylarsonic acid and dimethylarsinic acid) concentrations in human urine were positively correlated with estimated inorganic As intake. These results suggest that residents in these areas are exposed to As through consumption of groundwater and rice, and potential health risk of As is of great concern for these people. Urinary concentration ratios of dimethylarsinic acid to monomethylarsonic acid in children were higher than those in adults, especially among men, indicating greater As methylation capacity in children.",
Arsenic,1338692,"Assessment of mouth-level exposure to tobacco constituents in U.S. snus consumers Abstract: INTRODUCTION: When assessing the health risks associated with different tobacco product categories (e.g., combustible and noncombustible), it is important to understand exposure. Snus, a smokeless tobacco product with lower levels of most tobacco-related toxicants than cigarette smoke, has been recently introduced in the United States. The objective of this study was to evaluate the mouth-level exposure (MLE) to selected tobacco constituents from snus by adult consumers of Camel SNUS (CSNUS). METHODS: For 7 days, 53 adult CSNUS consumers used their usual brand styles ad libitum, collecting their snus pouches after use. The collected pouches and unused product were analyzed for nicotine, N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N'-nitrosoanabasine (NAB), N'-nitrosoanatabine (NAT), benzo[a]pyrene (B[a]P), arsenic, cadmium, chromium, lead, and nickel. MLE was estimated using the difference between the constituent amounts in the used and unused snus products. RESULTS: CSNUS consumption averaged 3.3 pouches/day or approximately 1.98g/day. Mean nicotine MLE was 2.8mg/pouch or 9.4mg/day. Mean MLE to total tobacco-specific nitrosamines (TSNAs: NNK, NNN, NAB, and NAT) was 171.5ng/pouch or 527.7ng/day. B[a]P MLE averaged 0.2ng/pouch or 0.68ng/day. CONCLUSIONS: This study is the first to report snus MLE under normal conditions of use in a group of adult, U.S. snus consumers. On average, approximately 60%-90% of the amounts of nicotine, TSNAs, and B[a]P initially present in a snus pouch remained in the pouch after use by snus consumers in this study. The results from this study provide a preliminary assessment of exposure to constituents present in snus, which is potentially useful in risk assessment.",
Arsenic,627947,"Dose-response relationship between ingested arsenic and cataracts among residents in Southwestern Taiwan Abstract: This association study was carried out to examine the effect of long-term exposure to ingested arsenic on various types of cataract. A total of 349 residents living in arseniasis-hyperendemic villages of southwestern Taiwan were recruited. Cumulative arsenic exposure was derived from the history of consuming artesian well water and the arsenic level in well water. The Lens Opacities System III was used to classify different types of cataract. The cataract surgery prevalence was 10% for the age group of 50 or more years. Cortical opacity was most common (35%), while nuclear and posterior subcapsular opacities were observed in 24% and 22% of subjects, respectively. Diabetes mellitus was a significant risk factor for all types of cataract. Occupational sunlight exposure was associated with cortical and posterior subcapsular opacities in a dose-response relationship. The cumulative exposure to arsenic from artesian well water and the duration of consuming artesian well water were associated with an increased risk of all types of lens opacity. But statistically significant dose-response relations with the cumulative arsenic exposure and the duration of consuming artesian well water were observed only for posterior subcapsular opacity (P=0.014 and P=0.023, respectively) after adjustment for age, sex, diabetes status, and occupational sunlight exposure. It was concluded that there was an increasing prevalence of posterior subcapsular opacity with the increase in exposure to ingested arsenic.",
Arsenic,1936064,"Effects of sodium arsenate exposure on liver fatty acid profiles and oxidative stress in rats Abstract: The present study aimed to evaluate the effect of arsenic on liver fatty acids (FA) composition, hepatotoxicity and oxidative status markers in rats. Male rats were randomly devised to six groups (n?=?10 per group) and exposed to sodium arsenate at a dose of 1 and 10 mg/l for 45 and 90 days. Arsenate exposure is associated with significant changes in the FA composition in liver. A significant increase of saturated fatty acids (SFA) in all treated groups (p?<?0.01) and trans unsaturated fatty acids (trans UFA) in rats exposed both for short term for 10 mg/l (p?<?0.05) and long term for 1 and 10 mg/l (p?<?0.001) was observed. However, the cis UFA were significantly decreased in these groups (p?<?0.05). A markedly increase of indicator in cell membrane viscosity expressed as SFA/UFA was reported in the treated groups (p?<?0.001). A significant increase in the level of malondialdehyde by 38.3 % after 90 days of exposure at 10 mg/l was observed. Compared to control rats, significant liver damage was observed at 10 mg/l of arsenate by increasing plasma marker enzymes after 90 days. It is through the histological investigations in hepatic tissues of exposed rats that these damage effects of arsenate were confirmed. The antioxidant perturbations were observed to be more important at groups treated by the high dose (p?<?0.05). An increase in the level of protein carbonyls was observed in all treated groups (p?<?0.05). The present study provides evidence for a direct effect of arsenite on FA composition disturbance causing an increase of SFA and TFAs isomers, liver dysfunction and oxidative stress. Therefore, arsenate can lead to hepatic damage and propensity towards liver cancer.",
Arsenic,2064274,"Size-fractionation of groundwater arsenic in alluvial aquifers of West Bengal, India: The role of organic and inorganic colloids Abstract: Dissolved organic carbon (DOC) and Fe mineral phases are known to influence the mobility of arsenic (As) in groundwater. Arsenic can be associated with colloidal particles containing organic matter and Fe. Currently, no data is available on the dissolved phase/colloidal association of As in groundwater of alluvial aquifers in West Bengal, India. This study investigated the fractional distribution of As (and other metals/metalloids) among the particulate, colloidal and dissolved phases in groundwater to decipher controlling behavior of organic and inorganic colloids on As mobility. The result shows that 83-94% of As remained in the 'truly dissolved' phases (i.e., &lt;0.05?m size). Strong positive correlation between Fe and As (r(2) between 0.65 and 0.94) is mainly observed in the larger (i.e., &gt;0.05?m size) colloidal particles, which indicates the close association of As with larger Fe-rich inorganic colloids. In smaller (i.e., &lt;0.05?m size) colloidal particles strong positive correlation is observed between As and DOC (r(2)=0.85), which highlights the close association of As with smaller organic colloids. As(III) is mainly associated with larger inorganic colloids, whereas, As(V) is associated with smaller organic/organometallic colloids. Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy confirm the association of As with DOC and Fe mineral phases suggesting the formation of dissolved organo-Fe complexes and colloidal organo-Fe oxide phases. Attenuated total reflectance-Fourier transform infrared spectroscopy further confirms the formation of As-Fe-NOM organometallic colloids, however, a detailed study of these types of colloids in natural waters is necessary to underpin their controlling behavior.",
Arsenic,2343537,"Geochemical behavior of arsenic in reducing sulfidic sediments of reservoir contaminated by acid mine drainage Abstract: The sediment from an acid mine drainage affected reservoir of Guizhou province of China has the iron and arsenic concentration of about 400 and 2.6 g/kg, respectively. Sediment cores were collected, and were used to study the arsenic behavior in the seriously acidified reservoir from the viewpoint of chemical thermodynamics. The limestone neutralization and ferric iron hydrolysis regulated the porewater pH from about 2.9-5.8. The reductive dissolution of As-Fe-rich (hydr)oxides under the mild acidic conditions was the main mechanism for the release of absorbed arsenic into porewater. The maximum concentrations of iron, sulfate and arsenic reached to about 2,800, 9,000 and 1 mg/l, respectively. Arsenic speciation transformation and hydrous ferric oxide (HFO) crystallization enhanced the arsenic mobility in sediment. In addition, the iron sulfide minerals diagenesis could play a role in removing the dissolved arsenic from porewater. The actual distribution of arsenic concentration in porewater was well simulated using the model of surface complexation of arsenic to HFO. Although arsenic concentration in porewater could be above 100 times higher than that of reservoir water, it was not easy to release into the reservoir water through diffusion, because the shallow sediment had relatively strong arsenic adsorption capacity, and new HFO could be generated continuously at the sediment water interface.",
Arsenic,627086,"Dietary arsenic exposure in Bangladesh Abstract: BACKGROUND: Millions of people in Bangladesh are at risk of chronic arsenic toxicity from drinking contaminated groundwater, but little is known about diet as an additional source of As exposure. METHODS: We employed a duplicate diet survey to quantify daily As intake in 47 women residing in Pabna, Bangladesh. All samples were analyzed for total As, and a subset of 35 samples were measured for inorganic arsenic (iAs) using inductively coupled plasma mass spectrometry equipped with a dynamic reaction cell. RESULTS: Median daily total As intake was 48 ?g As/day [interquartile range (IQR), 33–67) from food and 4 ?g As/day (IQR, 2–152) from drinking water. On average, iAs comprised 82% of the total As detected in dietary samples. After adjusting for the estimated inorganic fraction, 34% [95% confidence interval (CI), 21–49%] of all participants exceeded the World Health Organization’s provisional tolerable daily intake (PTDI) of 2.1 ?g As/kg-day. Two of the 33 women who used a well with < 50 ?g As/L exceeded this recommendation. CONCLUSIONS: When drinking water concentrations exceeded the Bangladesh drinking water standard of 50 ?g As/L, ingested water was the dominant source of exposure. However, as drinking water As concentrations decrease, the relative contribution of dietary As sources becomes more important to ingested dose. The combined intake from both diet and drinking water can cause some individuals to exceed the PTDI in spite of using a tube well that contains < 50 ?g As/L.",
Arsenic,1019592,"Microwave spectrum of the AsD2(X2B1) radical: Harmonic force field and molecular structure Abstract: The pure rotational spectrum of AsD2 in the 2B1 ground electronic state was measured in the frequency region of 268-398 GHz by microwave spectroscopy. The AsD2 radical was generated in a free-space cell by dc-glow discharge of a gaseous mixture of D2 and He over arsenic powder. Fifty fine and hyperfine components of nine rotational transitions were measured and analyzed by least-squares methods determining the detailed molecular constants of AsD2: the rotational constants, the centrifugal distortion constants, the spin-rotation coupling constant with the centrifugal distortion terms, and the hyperfine coupling constants associated with the arsenic and deuterium nuclei. The harmonic force field of AsH2 was determined from the centrifugal distortion constants, the equilibrium vibrational frequency of nu2 mode of AsH2, and the inertial defects of AsH2 and AsD2. The harmonic force field was used to calculate vibrational corrections to the rotational constants of both species and thus the zero-point average structures for both species were derived; AsH2: rz(AsH) = 1.53436(15) Å, thetaz(HAsH) = 90.695(20) degrees, and AsD2: rz(AsD) = 1.52902(13) Å, thetaz(DAsD) = 90.722(17) degrees, where the errors in parentheses are due to residual inertial defects of the corrected moments of inertia. From the difference between the rz structures for AsH2 and AsD2 the re structure of AsH2 is estimated to be re(AsH) = 1.5158(6) Å, thetae(HAsH) = 90.79(8) degrees.",
Arsenic,2347632,"Behavior of arsenic in the coastal area of the Changjiang (Yangtze River) Estuary: Influences of water mass mixing, the spring bloom and hypoxia Abstract: The biogeochemical cycle of arsenic in the aquatic environment has received scientific attention because of the complex forms and toxicity of this element. Previous studies have shown the frequent occurrence of hypoxia in the coastal area of the Changjiang (Yangtze River) Estuary. In an especially dry year (2006), three cruises were conducted (June, August and October) in this area to investigate the impact of hypoxia on total dissolved inorganic arsenic (TDIAs: [TDIAs] = [AsO43-] + [AsO33-]), dissolved organic arsenic (DOAs) and total arsenic in surface sediments. The distribution of TDIAs in the study area was similar among the three field studies, with high concentrations being found in the coastal area and in near bottom waters offshore in the East China Sea (ECS). TDIAs was scavenged in the surface layer in June. The distribution of DOAs was opposite that of TDIAs, especially in the region having high concentrations of chlorophyll-a (Chl-a). The DOAs/TDAs (total dissolved arsenic: [TDAs] = [DOAs] + [TDIAs]) ratio decreased from June to October. The concentrations of total arsenic in surface sediments decreased gradually from the Changjiang Estuary to the central ECS shelf. The behavior of TDIAs was non-conservative in the coastal area of the Changjiang Estuary. Biological mediation and hypoxia are the main factors influencing the internal cycling of arsenic within the study area. The DOAs/TDAs ratio was negatively correlated with apparent oxygen utilization (r=0.71, p &lt; 0.05, and n=33) in the hypoxic zone, which suggests that the decomposition of organic matter may have a significant effect on the internal transformations of various arsenic species in the coastal area of the Changjiang Estuary. Sediment-water incubation experiments conducted under various redox conditions showed that hypoxia resulted in the release of arsenic from the sediments into the water; this may contribute to the high TDIAs concentrations in bottom waters in August. With increased toxicity and residence time of inorganic arsenic species during hypoxia, the potential damage to the ecosystem and marine environment should receive more attention.",
Arsenic,1016082,"A transgenic Drosophila model for arsenic methylation suggests a metabolic rationale for differential dose-dependent toxicity endpoints Abstract: The mechanisms by which exposure to arsenic induces its myriad pathological effects are undoubtedly complex, while individual susceptibility to their type and severity is likely to be strongly influenced by genetic factors. Human metabolism of arsenic into methylated derivatives, once presumed to result in detoxification, may actually produce species with significantly greater pathological potential. We introduce a transgenic Drosophila model of arsenic methylation, allowing its consequences to be studied in a higher eukaryote exhibiting conservation of many genes and pathways with those of human cells while providing an important opportunity to uncover mechanistic details via the sophisticated genetic analysis for which the system is particularly well suited. The gene for the human enzyme, arsenic (+3 oxidation state) methyltransferase, was introduced into nonmethylating Drosophila under inducible control. Transgenic flies were characterized for enzyme inducibility, production of methylated arsenic species, and the dose-dependent consequences for chromosomal integrity and organismal longevity. Upon enzyme induction, transgenic flies processed arsenite into mono and dimethylated derivatives identical to those found in human urine. When induced flies were exposed to 9 ppm arsenite, chromosomal stability was clearly reduced, whereas at much higher doses, adult life span was significantly increased, a seemingly paradoxical pair of outcomes. Measurement of arsenic body burden in the presence or absence of methylation suggested that enhanced clearance of methylated species might explain this greater longevity under acutely toxic conditions. Our study clearly demonstrates both the hazards and the benefits of arsenic methylation in vivo and suggests a resolution based on evolutionary grounds.",
Arsenic,8597,"Whole-body retention, excretion and metabolism of [74As] arsenic acid in the hamster Abstract: In order to assess the whole-body retention, excretion and metabolism of inorganic arsenic, male and female hamsters were given either a single oral or i.v. dose of 74As(33? ?Ci/hamster; 0.01 ?g arsenic/hamster) as arsenic acid. 74As radioactivity was measured in the whole body, urine and feces for up to 35 days. 24-h samples of urine were analyzed for arsenic metabolites. For the i.v. dosed hamsters, the half-period of elimination for the first component (65% of the dose) was 0.40 days; the second component (35% of the dose) had a half-period of 4.5 days. For the orally dosed hamsters, the half-period of elimination for the first component (98% of the dose) was 0.29 days; the second component (2% of the dose) had a half-period of 3.8 days. Differences in the percent of dose excreted between oral and i.v. dosed hamsters appear to be due to the increased fecal excretion of arsenic (70%) in the orally dosed hamsters as compared to the i.v. dosed hamsters (6%). No statistically significant differences between the i.v. and oral treatments were found in the half- periods of elimination for either of the 2 components. Analysis of the urine for metabolites revealed arsenic was present as dimethylarsinic acid and inorganic arsenic.",
Arsenic,2279357,"Improved Diffusive Gradients in Thin Films (DGT) Measurement of Total Dissolved Inorganic Arsenic in Waters and Soils Using a Hydrous Zirconium Oxide Binding Layer Abstract: A high-capacity diffusive gradients in thin films (DGT) technique has been developed for measurement of total dissolved inorganic arsenic (As) using a long shelf life binding gel layer containing hydrous zirconium oxide (Zr-oxide). Both As(III) and As(V) were rapidly accumulated in the Zr-oxide gel and could be quantitatively recovered by elution using 1.0 M NaOH for freshwater or a mixture of 1.0 M NaOH and 1.0 M H2O2 for seawater. DGT uptake of As(III) and As(V) increased linearly with deployment time and was independent of pH (2.0-9.1), ionic strength (0.01-750 mM), the coexistence of phosphate (0.25-10 mg P L(-1)), and the aging of the Zr-oxide gel up to 24 months after production. The capacities of the Zr-oxide DGT were 159 ?g As(III) and 434 ?g As(V) per device for freshwater and 94 ?g As(III) and 152 ?g As(V) per device for seawater. These values were 5-29 times and 3-19 times more than those reported for the commonly used ferrihydrite and Metsorb DGTs, respectively. Deployments of the Zr-oxide DGT in As-spiked synthetic seawater provided accurate measurements of total dissolved inorganic As over the 96 h deployment, whereas ferrihydrite and Metsorb DGTs only measured the concentrations accurately up to 24 and 48 h, respectively. Deployments in soils showed that the Zr-oxide DGT was a reliable and robust tool, even for soil samples heavily polluted with As. In contrast, As in these soils was underestimated by ferrihydrite and Metsorb DGTs due to insufficient effective capacities, which were likely suppressed by the competing effects of phosphate.",
Arsenic,656821,"The association between frequencies of mitomycin C-induced sister chromatid exchange and cancer risk in arseniasis Abstract: In order to examine whether biomarkers of cytogenetic damage and susceptibility, such as spontaneous and mitomycin C-induced sister chromatid exchange (SCE) can predict cancer development, a nested case-control study was performed in a blackfoot endemic area with known high cancer risk. A cohort of 686 residents was recruited from three villages in the arseniasis area. Personal characteristics were collected and venous blood was drawn for lymphocyte culture and stored in a refrigerator. The vital status and cancer development was followed using the National Death Registry, Cancer Registry, and Blackfoot Disease Registry. The follow up period was from August 1991 to July 1997. During this 6-year-period, 55 residents developed various types of cancer. Blood culture samples from 23 of these subjects were unsuitable for spontaneous SCE experiments and 45 of these subjects were unsuitable for mitomycin C-induced SCE experiments due to improper storage. Finally, a total of 32 cancer cases had cytogenetic samples that could be analyzed. About 32 control subjects were selected from those who did not develop cancer in the study period and these subjects were matched to cases by sex, age, smoking habits, and residential area. The results showed that there was no significant difference in the frequencies of spontaneous and mitomycin C-induced SCE between the case and control groups. There was also no significant difference in the net difference of spontaneous and mitomycin C-induced SCE between the case and control groups. These results suggest that SCEs, either spontaneous or mitomycin C-induced, might not be good markers to predict cancer risk.",
Arsenic,2337242,"Determining heavy metals in spent compact fluorescent lamps (CFLs) and their waste management challenges: Some strategies for improving current conditions Abstract: From environmental viewpoint, the most important advantage of compact fluorescent lamps (CFLs) is reduction of green house gas emissions. But their significant disadvantage is disposal of spent lamps because of containing a few milligrams of toxic metals, especially mercury and lead. For a successful implementation of any waste management plan, availability of sufficient and accurate information on quantities and compositions of the generated waste and current management conditions is a fundamental prerequisite. In this study, CFLs were selected among 20 different brands in Iran. Content of heavy metals including mercury, lead, nickel, arsenic and chromium was determined by inductive coupled plasma (ICP). Two cities, Tehran and Tabriz, were selected for assessing the current waste management condition of CFLs. The study found that waste generation amount of CFLs in the country was about 159.80, 183.82 and 153.75 million per year in 2010, 2011 and 2012, respectively. Waste generation rate of CFLs in Iran was determined to be 2.05 per person in 2012. The average amount of mercury, lead, nickel, arsenic and chromium was 0.417, 2.33, 0.064, 0.056 and 0.012mg per lamp, respectively. Currently, waste of CFLs is disposed by municipal waste stream in waste landfills. For improving the current conditions, we propose by considering the successful experience of extended producer responsibility (EPR) in other electronic waste management. The EPR program with advanced recycling fee (ARF) is implemented for collecting and then recycling CFLs. For encouraging consumers to take the spent CFLs back at the end of the products' useful life, a proportion of ARF (for example, 50%) can be refunded. On the other hand, the government and Environmental Protection Agency should support and encourage recycling companies of CFLs both technically and financially in the first place.",
Arsenic,1032517,"Quality of community drinking water and the occurrence of spontaneous abortion Abstract: To investigate the relationship between community drinking water quality and spontaneous abortion, we compared trace element levels in the drinking water of 286 women having a spontaneous abortion through 27 wk gestation with that of 1,391 women having livebirths. Trace element levels were gathered from routine analyses of public tap water supplies from the communities where the women resided during pregnancy. After adjustment for potential confounders, an increase in the frequency of spontaneous abortion was associated with detectable levels of mercury; high levels of arsenic, potassium, and silica; moderately hard water, and surface water. In contrast, a decrease in the frequency of spontaneous abortion was associated with high levels of alkalinity and sulfate, and any detectable level of nitrate. These results require further corroboration because there is a paucity of data investigating this issue.",
Arsenic,1508681,"Assessment of arsenic surface contamination in a museum anthropology department Abstract: <strong>OBJECTIVE: </strong>: To assess potential arsenic (As) contamination of work surfaces to improve upon the control strategy at an anthropology department in a large natural history museum.<br /><br /><strong>METHODS: </strong>: Workpractices were observed and control strategy reviewed to inform an occupational hygiene assessment strategy utilizing surface wipe sampling. A total of 35 sampling targets were identified, focusing on surfaces that receive high touch traffic, including workstations, artifact transport carts, and elevator buttons. Arsenic sampling and analysis were performed using reference method Occupational Safety and Health Administration ID-125G.<br /><br /><strong>RESULTS: </strong>: Four of the sampling areas returned detectable levels of As, ranging from 0.052 to 0.350 ?g/100 cm.<br /><br /><strong>CONCLUSION: </strong>: Workplace observations and wipe sampling data enabled the development of recommendations to help to further reduce potential occupational exposure to As. Continuous reduction of surface contamination is prudent for known human carcinogens.",
Arsenic,2347646,"Higher urinary heavy metal, phthalate and arsenic concentrations accounted for 3-19% of the population attributable risk for high blood pressure: US NHANES, 2009-2012 Abstract: The link between environmental chemicals and human health has emerged, but has not been completely examined in terms of its risk factors. Therefore, we aimed to study the relationships of different sets of urinary environmental chemical concentrations and high blood pressure (BP) in a national, population-based study. Data were retrieved from the United States National Health and Nutrition Examination Surveys, 2009-2012, including demographics, BP readings and urinary environmental chemical concentrations. Analyses included ?(2)-test, t-test, survey-weighted logistic regression models and population attributable risk estimation. Urinary cesium (odds ratio (OR) 1.52, 95% confidence interval (CI) 1.06-2.18, P=0.026), molybdenum (OR 1.45, 95% CI 1.04-2.02, P=0.029), lead (OR 1.49, 95% CI 1.12-1.98, P=0.009), platinum (OR 1.66, 95% CI 1.14-2.21, P=0.002), antimony (OR 1.44, 95% CI 1.12-1.86, P=0.008) and tungsten (OR 1.48, 95% CI 1.22-1.79, P<0.001) concentrations were observed to be associated with high BP. Similar results were observed for mono-2-ethyl-5-carboxypentyl (OR 1.29, 95% CI 1.04-1.59, P=0.024), mono-n-butyl (OR 1.36, 95% CI 1.11-1.67, P=0.005), mono-2-ethyl-5-hydroxyhexyl (OR 1.21, 95% CI 1.01-1.46, P=0.041), mono-n-methyl (OR 1.24, 95% CI 1.01-1.46, P=0.014), mono-2-ethyl-5-oxohexyl (OR 1.21, 95% CI 1.01-1.45, P=0.036), mono-benzyl (OR 1.41, 95% CI 1.15-1.74, P=0.002), dimethylarsonic acid (OR 1.38, 95% CI 1.08-1.76, P=0.012) and trimethylarsine oxide (OR 2.56, 95% CI 1.29-5.07, P=0.010) concentrations. Each chemical could account for 3-19% of the population attributable risk for high BP. A small sex difference was found. However, there are no associations between environmental parabens and pesticides and high BP. Urinary heavy metal, phthalate and arsenic concentrations were associated with high BP, although a causal effect cannot be established. Elimination of environmental chemical exposure in humans still needs to be pursued.Hypertension Research advance online publication, 31 July 2014; doi:10.1038/hr.2014.121.",
Arsenic,2149287,Dissolution and Solubility of the Erythrite/Annabergite Solid Solution [(CoxNi1-x)(3)(AsO4)(2)center dot 8H(2)O] at 25 degrees C Abstract: ,
Arsenic,1508513,"Biosorption and toxicity responses to arsenite (As[III]) in Scenedesmus quadricauda Abstract: Toxicity and biosorption responses to arsenite (As[III]) were examined in a 96-h exposure study using Scenedesmus quadricauda, one of the most popular green algae distributed in freshwaters in China. Results indicated that the pH-dependent distribution of two arsenite species (H2AsO3- and H3AsO3) played an important role in biosorption and toxicity. The undissociated H3AsO3 was more toxic than its monoanionic H2AsO3- through comparison of algal cell numbers, chlorophyll-a contents, and algal ultrastructural changes observed with transmission electron microscopy. An effective biosorption of 89.0mgg-1 at 100mgL-1 As[III] was found in the treatments with an initial pH of 9.3 and 25.2?gg-1 at 0.03mgL-1 As[III] at an initial pH of 8.2 as a result of the predominant species of H2AsO3- under the ambient pH and Eh conditions. Our results imply that S. quadricauda may provide a new means for the removal of toxic arsenite species present in contaminated surface water.",
Arsenic,1519044,"Renin-angiotensin-aldosterone system activity in hyperthyroid cats with and without concurrent hypertension Abstract: BACKGROUND: Hypertension is present in some hyperthyroid cats at diagnosis or can develop after treatment for hyperthyroidism. Activation of the renin-angiotensin-aldosterone system (RAAS) could be involved in the pathogenesis of hypertension. HYPOTHESIS: Hyperthyroid cats that develop hypertension before or after treatment for hyperthyroidism will have greater RAAS activation than normotensive cats. ANIMALS: Ninety-nine hyperthyroid cats. METHODS: Retrospective case-control study. Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in untreated hyperthyroid hypertensive cats (HT-Pre group), initially normotensive hyperthyroid cats that develop hypertension after treatment (HT-Post group), and hyperthyroid cats that are normotensive (NT group). Data are presented as median [25th, 75th percentile]. RESULTS: Baseline PRA was not significantly different among the 3 groups (HT-Pre group 1.50 [0.05, 2.37] ng/mL/h, HT-Post group 0.66 [0.17, 2.31] ng/mL/h, NT group 1.11 [0.57, 2.18] ng/mL/h; P = .44). PRA decreased significantly after treatment in the NT group (1.09 [0.53, 2.47] versus 0.22 [0.05, 0.76] ng/mL/h; P &lt; .001) and the HT-Post group (0.71 [0.17, 2.33] versus 0.28 [0.07, 0.57] ng/mL/h; P = .006). Baseline PAC was not significantly different among the 3 groups (HT-Pre group 72.2 [40.0, 145.6] pg/mL, HT-Post group 69.7 [43.3, 142.6] pg/mL, NT group 109.0 [68.2, 184.6] pg/mL; P = .10). PAC decreased significantly after treatment in the NT group (114.4 [56.6, 204.1] versus 59.5 [32.4, 98.2] pg/mL; P &lt; .001) but did not change significantly in the HT-Post group (61.2 [44.9, 124.0] versus 58.4 [42.0, 97.7] pg/mL; P = .59). CONCLUSIONS AND CLINICAL IMPORTANCE: RAAS activation occurs in hyperthyroid cats, but is not associated with the development of hypertension. PAC is not influenced by changes in PRA in hyperthyroid cats that develop hypertension after treatment, perhaps indicating RAAS dysfunction in these cats.",
Arsenic,627047,"shRNA silencing of AS3MT expression minimizes arsenic methylation capacity of HepG2 cells Abstract: Several methyltransferases have been shown to catalyze the oxidative methylation of inorganic arsenic (iAs) in mammalian species. However, the relative contributions of these enzymes to the overall capacity of cells to methylate iAs have not been characterized. Arsenic (+3 oxidation state) methyltransferase (AS3MT) that is expressed in rat and human hepatocytes catalyzes the conversion of iAs, yielding methylated metabolites that contain arsenic in +3 or +5 oxidation states. This study used short hairpin RNA (shRNA) to knock down AS3MT expression in human hepatocellular carcinoma (HepG2) cells. In a stable clonal HepG2/A cell line, AS3MT mRNA and protein levels were reduced by 83 and 88%, respectively. In comparison, the capacity to methylate iAs decreased only by 70%. These data suggest that AS3MT is the major enzyme in this pathway, although an AS3MT-independent process may contribute to iAs methylation in human hepatic cells.",
Arsenic,1352269,"The modulation of thiol redox state affects the production and metabolism of hydrogen peroxide by heart mitochondria Abstract: In rat heart mitochondria, auranofin, arsenite, diamide, and BCNU increase H2O2 formation, further stimulated by antimycin. However, in submitochondrial particles, H2O2 formation and oxygen uptake are not affected, indicating that these substances do not alter respiration. Mitochondria are also able to rapidly metabolize added H2O2 in a process partially prevented by BCNU or auranofin. Calcium does not modify the production of H2O2 and the mitochondrial thioredoxin system is not affected by calcium ions. Auranofin, arsenite, and diamide determine a large mitochondrial permeability transition, while BCNU and acetoacetate are ineffective. Thiols and glutathione are modified only by BCNU and diamide. However, all the compounds tested cause the release of cytochrome c that occurs also in the absence of mitochondrial swelling. In conclusion, the compounds utilized share the common feature of shifting the mitochondrial thiol-linked redox balance towards a more oxidized condition that is responsible of the observed effects.",
Arsenic,1248866,"Histone deacetylase 6 associates with ribosomes and regulates de novo protein translation during arsenite stress Abstract: Histone deacetylase 6 (HDAC6) is known as a cytoplasmic enzyme that regulates cell migration, cell adhesion, and degradation of misfolded proteins by deacetylating substrates such as ?-tubulin and Hsp90. When HaCaT keratinocytes were exposed to 1-200?M sodium arsenite, we observed perinuclear localization of HDAC6 within 30 min. Although the overall level of HDAC6 protein did not change, sodium arsenite caused an increase of HDAC6 in ribosomal fractions. Separation of ribosomal subunits versus intact ribosomes or polysomes indicated that HDAC6 was mainly detected in 40/43S fractions containing the small ribosomal subunit in untreated cells but was associated with 40/43S and 60/80S ribosomal fractions in arsenite-treated cells. Immunocytochemistry studies revealed that arsenite caused colocalization of HDAC6 with the ribosomal large and small subunit protein L36a and S6. Both L36a and S6 were detected in the immunocomplex of HDAC6 isolated from arsenite-treated cells. The observed physical interaction of HDAC6 with ribosomes pointed to a role of HDAC6 in stress-induced protein translation. Among arsenite stress-induced proteins, de novo Nrf2 protein translation was inhibited by Tubastatin A. These data demonstrate that HDAC6 was recruited to ribosomes, physically interacted with ribosomal proteins, and regulated de novo protein translation in keratinocytes responding to arsenite stress.",
Arsenic,1794807,"Joint effects of heavy metal binary mixtures on seed germination, root and shoot growth, bacterial bioluminescence, and gene mutation Abstract: ",
Arsenic,1070478,"Prenatal exposure to arsenic and its effects on fetal development in the general population of Dalian Abstract: To evaluate prenatal exposure to arsenic in the general population and its effects on birth size, we conducted a cross-sectional study in Dalian, China. Arsenic concentration in maternal and cord blood was detected by inductively coupled plasma-mass spectrometry and its effects on birth size were analyzed by multivariate analysis and multiple linear regression analysis. Arsenic concentrations in cord blood were significantly lower than those in maternal blood. A significant positive correlation was shown between maternal and cord blood arsenic concentrations. Maternal arsenic concentration was negatively associated with birth weight, height and chest circumference, and fetal arsenic concentration was negatively associated with head circumference. Our results indicate that arsenic exposure at environmental levels in uterus may pose adverse effects on fetal development.",
Arsenic,1252103,"Dimethylarsinic acid effects on DNA damage and oxidative stress related biochemical parameters in B6C3F1 mice Abstract: Adult female B6C3F1 mice were given 720 mg/kg of DMA by oral gavage at one of three times (2 h, 15 h, or at both 21 and 4 h) before sacrifice. Significant (P &lt; 0.05) decreases in liver GSH and GSSG contents (15-37%) were observed. Some evidence of DMA-induced hepatic DNA damage (at the P &lt; 0.10 level only) was observed. Pulmonary and hepatic ODC activities were reduced (19-59%) by DMA treatment. Overall, these biochemical studies show that mice are much less responsive to DMA than rats.",
Arsenic,1786298,"Rhizoreduction of arsenate and chromate in Australian native grass, shrub and tree vegetation Abstract: Background and aims Rhizosphere influences the dynamics of nutrients and contaminants through increased microbial activity, release of root exudates and alteration of pH. The objective of this study was to evaluate the rhizosphere-induced reduction (i.e. rhizoreduction) and redistribution of arsenate [As(V)] and chromate [Cr(VI)] in Australian native vegetation in relation to their bioavailability. Methods The reduction of As(V) and Cr(VI) was examined using rhizosphere soils from a number of Australian native vegetation (Acacia pubescens, Eucalyptus camaldulensis, Enchylaena tomentosa, Templetonia retusa, Dichantheum sericeum and Austrodanthonia richardsonii). Naturally contaminated As and Cr soils were used to examine the effect of Dichantheum sericeum on the redistribution and bioavailability of these metal(loid)s. Results The rhizosphere soil contained higher levels of microbial activity, dissolved organic carbon and organic acid content than the non-rhizosphere soil. The rhizosphere soil caused up to 2.4 and 5.1 fold increases in the rate of reduction of As(V) and Cr(VI), respectively. There was a significant relationship between rhizosphere-induced increases in microbial activity (? basal respiration) and As(V) and Cr(VI) reduction (? rate of reduction), indicating the role of increased microbial activity in rhizosphere soil on metal(loid) reduction. In the plant growth experiment, Dichantheum sericeum enhanced the reduction of metal(loid)s in the naturally contaminated soils, thereby increasing the bioavailability of As but decreasing that of Cr. Conclusions Depending on the nature of metal(loid)s present in soil, the rhizosphere-induced reduction by plant species such as Dichantheum sericeum and Templetonia retusa has implications to both their bioavailability to higher plants and microorganisms, and remediation of contaminated soils. While rhizoreduction decreases Cr bioavailability it increases that of As.",
Arsenic,1031779,"The expression of colligin/hsp47 after stress in human periodontal fibroblasts in vitro Abstract: Fibroblasts from human periodontal ligaments were grown in vitro. The levels of collagen and total protein in these cells were compared with subject- and passage-matched gingival fibroblasts. In 3 subjects the levels of both were greater in ligament than in gingival fibroblasts. These increased levels were also associated with increased levels of proteins reacting with anti-colligin/hsp47 antibodies on SDS-PAGE. Ligament and gingival fibroblasts were subjected to heat shock, sodium arsenite and the amino acid analogue AZC. These studies showed that (a) sodium arsenite and AZC enhanced the cellular levels of hsp47 in both types of fibroblast, (b) the colligin/hsp47 levels expressed were associated with elevated levels of protein and collagen production and (c) the presence of colligin/hsp47 was decreased under conditions of serum deprivation.",
Arsenic,711031,"Role of aquaporin 9 in cellular accumulation of arsenic and its cytotoxicity in primary mouse hepatocytes Abstract: Aquaporin (AQP) 9 is a member of the aquaglyceroporin subfamily of AQPs in the transfer of water and small solutes such as glycerol and arsenite. It is well recognized that arsenic toxicity is associated with intracellular accumulation of this metalloid. In the present study, we examined the contribution of AQP9 to the uptake of inorganic arsenite, thereby increasing arsenic-induced cytotoxicity in primary mouse hepatocytes. Pretreatment with sorbitol as a competitive inhibitor of AQP9 and siRNA-mediated knockdown of AQP9 resulted in a significant decrease of arsenite uptake in the cell and its cytotoxicity. Furthermore, overexpression of AQP9 in HEK293 cells led to the enhancement of intracellular arsenic concentration, resulting in enhanced cytotoxicity after arsenite exposure. These results suggest that AQP9 is a channel to define arsenite sensitivity in primary mouse hepatocytes.",
Arsenic,2278048,"Human health risks of geothermally derived metals and other contaminants in wild-caught food Abstract: Arsenic (As) and mercury (Hg) associated with geothermally influenced lakes and rivers represent a potential health risk to communities where wild-caught food is consumed. The Rotorua Lakes region of New Zealand has extensive natural geothermal activity and a large proportion (35%) of indigenous M?ori population, for whom wild food gathering is an important cultural activity. The aim of this study was to measure selected heavy metal and organochlorine (OC) concentrations in important local fish and shellfish species and assess the potential health risk to the local population of consuming these species. Following U.S. Environmental Protection Agency (EPA) protocols, consumption limits were calculated based on both excess lifetime cancer risk and noncancer risk. These were compared with local consumption rates, which were determined by questionnaire (n?=?19). Median and 95th percentile contaminant concentrations were calculated to approximate random and most extreme contaminant consumption scenarios. Only Hg concentrations exceeded established Food Standards Australia New Zealand (FSANZ) guideline values of 0.5 mg/kg, namely, for rainbow trout (Oncorhynchus mykiss; 62% of the study sites) and koura (freshwater crayfish; Paranephrops planifrons; 25% of sites). The major risk was from consumption of trout, where the local consumption rate (1.5 meals/mo) exceeded the consumption limit of 0.9 meals/mo (median data) and 0.4 meals/mo (95th percentile data). Shellfish-pipi (Paphies australis) and mussel (Perna canaliculus)-collected from the only estuarine site also had local consumption rates (3.5 meals/mo) above calculated consumption limits (2.6 and 2.9 meals/mo, respectively). Our results, while based on a limited sample size and therefore exploratory in nature, nevertheless provide the basis for developing consumption guidelines. This study makes a significant contribution to broadening our understanding of the complexities of managing customary fisheries.",
Arsenic,1021459,"Mercury and other heavy metals in free-ranging mink of the lower Great Lakes basin, Canada, 1998-2006 Abstract: Mercury concentrations were examined in livers of free-ranging mink (Neovison vison) trapped in the lower Great Lakes basin from 1998 to 2006. Significant geographic variation in total mercury levels was found in mink from 13 Great Lakes locations, many of which are within Great Lakes Areas of Concern (AOCs). Total mercury levels in mink from these locations were generally low to moderate, with means (±SE) ranging from 0.99 (±0.36) ?g/g dry weight in mink from inland Lake Erie to 7.31 (±1.52) ?g/g in mink from Walpole Island in the St. Clair River AOC. Overall, mercury exposure was highest in mink trapped in locations associated with large riverine wetlands. Total mercury concentrations were negatively related to the percentage of mercury present as methylmercury and positively related to selenium concentrations, consistent with increasing demethylation of methylmercury with increasing total mercury concentrations. One-year old mink had significantly higher levels of mercury and selenium than mink under 1 year but similar to mink 2 years of age and older. Mercury levels were below those associated with mercury toxicity. Concentrations of cadmium, lead and arsenic were low and largely associated with environmental background levels. Significant age and sex effects were found for cadmium. Lead levels were significantly lower in mink infected by the lung nematode parasite compared to uninfected animals. Further studies of biomagnification of methylmercury in wetland environments, where top predators such as mink may be an increased risk of exposure, are warranted.",
Arsenic,1332331,"Arsenite efflux is inhibited by verapamil, cyclosporin A, and GSH-depleting agents in arsenite-resistant Chinese hamster ovary cells Abstract: We have previously demonstrated that arsenite-resistant SA7 cells can extrude arsenite more effectively and completely than their parental Chinese hamster ovary cells. Our present results show that arsenite efflux from SA7 cells is inhibited by chemosensitizing agents to multidrug resistant-associated protein: verapamil and cyclosporin A and by glutathione-depleting agents: dinitrofluorobenzene and diethyl maleate. These results suggest that arsenite extrusion in SA7 cells may be mediated by a GSH-dependent and verapamil- and cyclosporin A-sensitive membrane transport system. Since arsenite extrusion was found dose-dependently inhibited by energy poison [potassium cyanide (KCN)] and an ATPase inhibitor (sodium vanadate), ATP is apparently required for arsenite extrusion in SA7 cells.",1
Arsenic,2279145,"Global assessment of arsenic pollution using sperm whales (Physeter macrocephalus) as an emerging aquatic model organism Abstract: Arsenic is an oceanic pollutant of global concern due to its toxicity, ability to bioaccumulate and continued input into the environment by anthropogenic activities. The sperm whale (Physeter macrocephalus) is an emerging aquatic model for both human disease and ocean health having global distribution and high trophic level. The aim of this study was to establish global and regional baselines of total arsenic concentrations using free-ranging sperm whales. Skin biopsies (n=342) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age in males. Arsenic was detectable in 99% of samples with a global mean of 1.9?g/g ww ranging from 0.1 to 15.6?g/g ww. Previous work in toothed whale skin found mean concentrations 3 fold lower with 0.6?g/g ww. A significant gender-related effect was found with males having higher mean arsenic concentrations than females. There was no significant age-related effect between adult and subadult males. Arsenic concentrations in sloughed skin samples were similar to levels in skin biopsies indicating that arsenic excretion can occur by skin sloughing. Regional mean concentrations were highest in the Maldives, Seychelles and Sri Lanka with 3.5, 2.5, and 2.4?g/g ww, respectively, raising concern for arsenic pollution in the Indian Ocean. Literature suggests that arsenic exposure is emitted from natural sources and the heavy use of arsenic-containing pesticides and herbicides in this region. These data suggest that research is needed in determining the extent and source of arsenic pollution in the Indian Ocean.",
Arsenic,1677519,"Relationship of metal enrichment with adverse biological effect in the Yangtze Estuary sediments: Role of metal background values Abstract: Exclusive pristine values of As, Cd, Cr, Cu, Fe, Mn, Pb, and Zn in the Yangtze Estuary are calculated using principal components analysis (PCA) to probe the relationship between degrees of metal enrichment and their adverse biological effects. The results show that obvious differences in the degrees of metal enrichment exist when the enrichment factors are analyzed with reference background values on global, national, and local scales. Based on the low variability of aluminum, the exclusive metal background values in the estuary are obtained with PCA and are more likely to reflect the pristine contents of the abovementioned metals in the Yangtze Estuary. For the six most common metals (As, Cd, Cr, Cu, Pb, and Zn), significant correlations exist between the enrichment factors and their adverse biological effects. Arsenic shows the highest potential to cause adverse effects despite its general lack of enrichment. However, Cd is the most conservative element and is not likely to cause biological effects in the estuary.",
Arsenic,1016543,"High selenium status in individuals exposed to arsenic through coal-burning in Shaanxi (PR of China) modulates antioxidant enzymes, heme oxygenase-1 and DNA damage Abstract: <strong>BACKGROUND: </strong>Although interactions of arsenite and selenite in mammalian organisms have been suggested by literature data, the antioxidant effects and biochemical mechanisms of dietary selenium on human populations exposed to inorganic arsenic are not fully understood.<br /><br /><strong>METHODS: </strong>Total blood, urine and hair concentrations of arsenic and selenium were determined in all individuals by hydride generation atomic fluorescence spectrometry. The individuals with skin lesions were subsequently classified as &quot;High As group&quot; and &quot;High Se/As group&quot; and controls were classified as &quot;High Se group&quot; and &quot;Control group&quot; according to their blood selenium concentrations.<br /><br /><strong>RESULTS: </strong>High selenium status was correlated with elevated activities of serum superoxide dismutase, glutathione peroxidase, catalase, and reduced levels of malondialdehyde, and increased RNA and protein expression of heme oxygenase-1 in peripheral blood mononuclear cells (PBMC) of individuals in the high arsenic group. Urinary 8-hydroxy-2'-deoxyguanosine levels were positively associated with blood arsenic, but inversely with blood and hair selenium among individuals with skin lesions, whereas mRNA are protein levels of 8-oxoganine DNA glycosylase 1 in PBMC increased in the &quot;High Se/As group&quot; compared to the &quot;High As group&quot;.<br /><br /><strong>CONCLUSIONS: </strong>Inorganic arsenic exposure is associated with oxidative stress, which may be prevented by high selenium status via its antioxidative activity and detoxification effect possibly through the formation of an arsenic and selenium containing metabolite, the seleno-bis(S-glutathionyl) arsinium ion.",
Arsenic,2064218,"The mortality and cancer experience of New Zealand Vietnam war veterans: A cohort study Abstract: <strong>OBJECTIVES: </strong>The aim was to observe the patterns of mortality and cancer incidence in New Zealand Vietnam veterans. The objectives were to assess whether the patterns of disease observed were consistent with those associated with military service in Vietnam, and similar to the patterns identified in other groups of Vietnam veterans.<br /><br /><strong>DESIGN: </strong>A historical cohort study.<br /><br /><strong>SETTING: </strong>Veterans, identified from service records, with Vietnam service between 1964 and 1972.<br /><br /><strong>PARTICIPANTS: </strong>Of the 3322 survivors of Vietnam service, we followed up 2783 (84%).<br /><br /><strong>OUTCOME MEASURES: </strong>Standardised mortality and incidence ratios (SMRs and SIRs, respectively) were calculated based on the number of deaths and cancer registrations observed, those expected being based on New Zealand national rates.<br /><br /><strong>RESULTS: </strong>All cause mortality was significantly reduced (SMR 0.85, 95% CI 0.77 to 0.94) and cancer incidence non-significantly increased (SIR 1.06, 95% CI 0.97 to 1.16). The risk of mortality from cancers of the head and neck (SMR 2.20, 95% CI 1.09 to 3.93); oral cavity pharynx and larynx (SMR 2.13, 95% CI 1.06 to 3.81) and the incidence of chronic lymphatic leukaemia (CLL) (SIR 1.91, 95% CI 1.04 to 3.20) were, however, significantly increased. Other lymphohaematopoietic disorders, specifically multiple myeloma and Hodgkin disease, showed non-significant mortality excesses, reflected by a similar increase in incidence.<br /><br /><strong>CONCLUSIONS: </strong>Service in the Vietnam war was associated with defoliant herbicide exposure, including 2,4,5-trichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, picloram and cacodylic acid. Subsequent reviews of mechanistic, animal and epidemiological evidence led to certain conditions being deemed compensable. The pattern of mortality and cancer incidence is not at odds with the list of compensable conditions and consistent with that found in Australian veterans serving in the same area of Vietnam, but also consistent with smoking and the healthy soldier effect. In common with the Australian experience, this is the only veterans group to show a significant excess of CLL.",
Arsenic,1339403,"[Migration of eight harmful elements from metal accessories that infants may swallow by mistake] Abstract: The International Standard ISO 8124-3:2010 &quot;Safety of toys--Part 3: Migration of certain elements&quot; controls the levels of migrated eight harmful elements (antimony, arsenic, barium, cadmium, chromium, lead, mercury and selenium) from infants toys. Moreover, the Japanese Food Sanitation Law controls the levels of migrated lead from metal accessory toys. However, the levels of migrated harmful elements from metal accessories that are not infants toys are not controlled, since they are not covered by the ISO Standard or the Food Sanitation Law. Therefore, we investigated the level of eight harmful elements migrated from metal accessories that infants may swallow by mistake. The extraction test of ISO 8124-3:2010 was executed in 117 products (total 184 specimens), and the concentration of these eight elements was measured by inductively coupled plasma mass spectroscopy (ICP-MS). As a result, 28 and one products released lead and cadmium beyond the maximum acceptable levels of the ISO standard, respectively. Metal accessories that infants may swallow by mistake should ideally not release harmful elements such as lead and cadmium.",
Arsenic,1031755,"Arsenic distribution in rabbits after Lewisite administration and treatment with British anti-Lewisite (BAL) Abstract: The standard treatment of Lewisite (dichloro(2-chlorovinyl)arsine) poisoning is by chelation with BAL (British anti-Lewisite, dimercaptopropanol). The present study investigated the effect of BAL treatment on the distribution of arsenic after Lewisite administration. Lewisite was administered subcutaneously at the LD10 and LD40 of the compound. Without BAL treatment arsenic was eliminated with a half-life in blood of between 55 and 75 hr and a blood clearance of 120 ml/hr/kg. Arsenic had a large volume of distribution of several liters per kilogram, indicating extensive distribution in tissues. The highest tissue concentrations, more than seven times blood concentrations, were found in the liver, lung, and kidneys. These organs maintained an approximately constant concentration ratio with blood during the sampling period. Concentrations in tissues with a blood-to-tissue barrier, such as the brain and the spinal cord, rose between 4 and 96 hr while blood concentrations declined more than fourfold over the same time period. BAL treatment by four equal, maximally tolerated doses over 12 hr substantially reduced arsenic concentrations in blood and tissues. For example, at 24 hr the concentrations in brain and liver (target organs for arsenic toxicity) were reduced by 65 to 89% over the range of Lewisite doses administered. The total exposure of brain and spinal cord was reduced by more than two-thirds by BAL treatment. Further, the blood clearance of arsenic was increased. BAL treatment enhanced the elimination of arsenic in two ways: by decreasing the tissue-to-blood partitioning which mobilizes arsenic into the blood stream, and by increasing the clearance of arsenic.",
Arsenic,1337294,"Using indicator kriging for the evaluation of arsenic potential contamination in an abandoned mining area (Portugal) Abstract: Mining and mineral-processing activities can modify the environment in a variety of ways. Sulfide mineralization is notorious for producing waters with high metal contents. Arsenic is commonly associated with sulfide mineralization and is considered to be toxic in the environment at low levels. The studied abandoned mining area is located in central Portugal and the resulting tailings and rejected materials were deposited and exposed to the air and water for the last 50years. Sixteen water sample-points were collected. One of these was collected outside the mining influence, with the aim of obtaining a reference background. The risk assessment, concerning the proximity to abandoned mineralized deposits, needs the evaluation of intrinsic and specific vulnerabilities aiming the quantification of the anthropogenic activities. In this study, two indicator variables were constructed. The first one (I(1)), a specific vulnerability, considers the arsenic water supply standard value (0.05mg/L), and the probability of it being exceeded is dependent on the geologic and hydrological characteristics of the studied area and also on the anthropogenic activities. The second one (I(2)), an intrinsic vulnerability, considers arsenic background limit as cut-off value, and depends only on the geologic and hydro-geological characteristics of the studied area. At Segura, the arsenic water content found during December 2006 (1.190mg/L) was higher than the arsenic water content detected in October 2006 (0.636mg/L) which could be associated to the arsenic released from Fe oxy-hydroxide. At Segura abandoned mining area, the iso-probability maps of October 2006 and December 2006, show strong anomalies associated with the water drainage from abandoned mining activities. Near the village, the probability of exceeding the arsenic background value is high but lower than the probability of exceeding the arsenic water supply value. The arsenic anomalies indicate a high probability for water arsenic contamination and those waters should not be used for human consumption.",
Arsenic,736386,"Urinary arsenic profile affects the risk of urothelial carcinoma even at low arsenic exposure Abstract: Arsenic exposure is associated with an increased risk of urothelial carcinoma (UC). To explore the association between individual risk and urinary arsenic profile in subjects without evident exposure, 177 UC cases and 313 age-matched controls were recruited between September 2002 and May 2004 for a case-control study. Urinary arsenic species including the following three categories, inorganic arsenic (As(III)+As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)), were determined with high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Arsenic methylation profile was assessed by percentages of various arsenic species in the sum of the three categories measured. The primary methylation index (PMI) was defined as the ratio between MMA(V) and inorganic arsenic. Secondary methylation index (SMI) was determined as the ratio between DMA(V) and MMA(V). Smoking is associated with a significant risk of UC in a dose-dependent manner. After multivariate adjustment, UC cases had a significantly higher sum of all the urinary species measured, higher percent MMA(V), lower percent DMA(V), higher PMI and lower SMI values compared with controls. Smoking interacts with the urinary arsenic profile in modifying the UC risk. Differential carcinogenic effects of the urinary arsenic profile, however, were seen more prominently in non-smokers than in smokers, suggesting that smoking is not the only major environmental source of arsenic contamination since the UC risk differs in non-smokers. Subjects who have an unfavorable urinary arsenic profile have an increased UC risk even at low exposure levels.",
Arsenic,1026185,"Spatial and temporal variations in arsenic exposure via drinking-water in northern Argentina Abstract: This study evaluated the spatial, temporal and inter-individual variations in exposure to arsenic via drinking-water in Northern Argentina, based on measurements of arsenic in water, urine, and hair. Arsenic concentrations in drinking-water varied markedly among locations, from <1 to about 200 ?g/L. Over a 10-year period, water from the same source in San Antonio de los Cobres fluctuated within 140 and 220 ?g/L, with no trend of decreasing concentration. Arsenic concentrations in women's urine (3-900 ?g/L, specific weight 1.018 g/mL) highly correlated with concentrations in water on a group level, but showed marked variations between individuals. Arsenic concentrations in hair (range 20-1,500 ?g/kg) rather poorly correlated with urinary arsenic, possibly due to external contamination. Thus, arsenic concentration in urine seems to be a better marker of individual arsenic exposure than concentrations in drinking-water and hair.",
Arsenic,1508630,"Arsenic contaminated groundwater and its treatment options in Bangladesh Abstract: Arsenic (As) causes health concerns due to its significant toxicity and worldwide presence in drinking water and groundwater. The major sources of As pollution may be natural process such as dissolution of As-containing minerals and anthropogenic activities such as percolation of water from mines, etc. The maximum contaminant level for total As in potable water has been established as 10 µg/L. Among the countries facing As contamination problems, Bangladesh is the most affected. Up to 77 million people in Bangladesh have been exposed to toxic levels of arsenic from drinking water. Therefore, it has become an urgent need to provide As-free drinking water in rural households throughout Bangladesh. This paper provides a comprehensive overview on the recent data on arsenic contamination status, its sources and reasons of mobilization and the exposure pathways in Bangladesh. Very little literature has focused on the removal of As from groundwaters in developing countries and thus this paper aims to review the As removal technologies and be a useful resource for researchers or policy makers to help identify and investigate useful treatment options. While a number of technological developments in arsenic removal have taken place, we must consider variations in sources and quality characteristics of As polluted water and differences in the socio-economic and literacy conditions of people, and then aim at improving effectiveness in arsenic removal, reducing the cost of the system, making the technology user friendly, overcoming maintenance problems and resolving sludge management issues.",
Arsenic,2149347,Arsenic oxidation treatment by H2O2 and UV radiation Abstract: ,
Arsenic,1936078,"WRKY6 transcription factor restricts arsenate uptake and transposon activation in arabidopsis Abstract: Stress constantly challenges plant adaptation to the environment. Of all stress types, arsenic was a major threat during the early evolution of plants. The most prevalent chemical form of arsenic is arsenate, whose similarity to phosphate renders it easily incorporated into cells via the phosphate transporters. Here, we found that arsenate stress provokes a notable transposon burst in plants, in coordination with arsenate/phosphate transporter repression, which immediately restricts arsenate uptake. This repression was accompanied by delocalization of the phosphate transporter from the plasma membrane. When arsenate was removed, the system rapidly restored transcriptional expression and membrane localization of the transporter. We identify WRKY6 as an arsenate-responsive transcription factor that mediates arsenate/phosphate transporter gene expression and restricts arsenate-induced transposon activation. Plants therefore have a dual WRKY-dependent signaling mechanism that modulates arsenate uptake and transposon expression, providing a coordinated strategy for arsenate tolerance and transposon gene silencing.",
Arsenic,1519230,Application of Near-infrared Spectroscopy in Micro Inorganic Analysis Abstract: ,
Arsenic,1021531,"DNA damage and decreased DNA repair in peripheral blood mononuclear cells in individuals exposed to arsenic and lead in a mining site Abstract: The aim of this study was to evaluate DNA damage and the capacity for DNA repair in children exposed to arsenic and lead. During 2006, we studied a total of 85 healthy children (aged 4-11 years) who were residents of Villa de la Paz (community A), Matehuala (community B), and Soledad de Graciano Sanchez (community C) in San Luis Potosi, Mexico. The quantification of arsenic in urine (AsU) and lead in blood (PbB) was performed by atomic absorption spectrophotometry. The alkaline comet assay was used to evaluate DNA damage and DNA repair. The highest levels of AsU and PbB in children were found in community A (44.5 ?g/g creatinine for arsenic and 11.4 ?g/dL for lead), followed by community B (16.8 ?g/g creatinine for arsenic and 7.3 ?g/dL for lead) and finally by children living in community C (12.8 ?g/g creatinine for arsenic and 5.3 ?g/dL for lead). When DNA damage was assessed, children living in community A had the highest DNA damage. Analysis of these same cells 1 h after a challenge with H(2)O(2) 10 ?M showed a dramatic increase in DNA damage in the cells of children living in community B and community C, but not in the cells of children living in community A. Moreover, significantly higher levels of DNA damage were observed 3 h after the challenge ended (repair period) in cells from individuals living in community A. Our results show that children exposed to metals might be more susceptible to DNA alterations.",
Arsenic,1936091,"Reduced hemopexin levels in peritoneal fluid of patients with endometriosis Abstract: <strong>OBJECTIVE: </strong>To study altered hemopexin concentrations in peritoneal fluid (PF) samples from patients with endometriosis. Recent data implicate a role of altered iron metabolism in endometriosis patients. Hemopexin is the major transport protein for heme. Like iron, heme exposure to the epithelial surface can provoke oxidative stress on the peritoneal epithelium. Therefore, altered hemopexin concentrations and heme scavenging in PF might play a role in the pathophysiology of endometriosis.<br /><br /><strong>DESIGN: </strong>Prospective explorative study.<br /><br /><strong>SETTING: </strong>Academic tertiary care center.<br /><br /><strong>PATIENT(S): </strong>Eighty symptomatic patients scheduled for laparoscopy for the diagnosis and/or therapy of endometriosis.<br /><br /><strong>INTERVENTION(S): </strong>Aspiration of PF samples during laparoscopy.<br /><br /><strong>MAIN OUTCOME MEASURE(S): </strong>Hemopexin and heme concentration in PF.<br /><br /><strong>RESULT(S): </strong>At laparoscopy, 47 of 80 (58.8%) patients exhibited endometriosis, and 33 (41.2%) were proven disease-free (CO). By means of ELISA significantly lower concentrations of hemopexin in the samples from patients with endometriosis (endometriosis 0.377 ± 0.16 mg/mL) compared with controls (disease-free 0.479 ± 0.20 mg/mL) could be demonstrated. Heme levels in the samples were not significantly different between groups (endometriosis 9.130 ± 6.124 ?M and disease-free 9.990 ± 4.485 ?M). There was no significant correlation between heme and hemopexin levels (Pearson's correlation coefficient r = -0.146). Demographic data between the groups were comparable.<br /><br /><strong>CONCLUSION(S): </strong>These data provide further evidence that hemopexin is significantly down-regulated in PF samples from patients with endometriosis compared with controls. This study confirms recent findings in two-dimensional gel electrophoresis demonstrating a down-regulation of hemopexin in PF from patients with endometriosis in a larger series of samples.",
Arsenic,1343983,"Preparation and spectroscopic characterisation of dithia-arsolium and -stibolium cations: Evidence for p?-p? bonding of sulphur with arsenic and antimony Abstract: 5-Methyl-1,3,2-benzodithiarsolium and 5-methyl-1,3,2-benzodithiastibolium cations have been prepared and the naphthalenic nature of the compounds is strong is evidence for the presence of unique p?-p? bonding of sulphur to arsenic and antimony.",
Arsenic,2337121,"Evaluation of heavy metals contamination in Iranian foodstuffs: canned tomato paste and tomato sauce (ketchup) Abstract: One hundred and thirty-five samples of canned tomato paste and 30 tomato sauces (ketchup) samples (23 and 10 brands, respectively) purchased from wholesale markets in the Tehran, Iran, during the period 2010-2013 were analysed. Levels of lead and cadmium were determined by graphite furnace atomic absorption spectrophotometer (GF-AAS) and arsenic by hydride vapour generation (HG-AAS or VGA). Average concentration of arsenic found in the tomato paste and ketchup samples was 62 +/- 14 and 48 +/- 12ngg(-1), respectively. Cadmium values in 7% of tomato paste and 10% of ketchup samples were below the limit of quantification (LOQ). Lead concentrations were below LOQ in 75% of tomato paste and 77% of ketchup samples. Values obtained for these heavy metals in all samples were lower than the limits of national and international standards.",
Arsenic,1350799,"The challenge of health & environment: Profiling risks & strategic priorities for now & the future Abstract: A substantial burden of communicable and non-communicable diseases in the developing countries is attributable to environmental risk factors. WHO estimates that the environmental factors are responsible for an estimated 24 per cent of the global burden of disease in terms of healthy life years lost and 23 per cent of all deaths; children being the worst sufferers. Given that the environment is linked with most of the Millennium Development Goals (MDGs), without proper attention to the environmental risk factors and their management, it will be difficult to achieve many MDGs by 2015. The impact of environmental degradation on health may continue well into the future and the situation in fact, is likely to get worse. In order to address this challenge, two facts are worth noting. First, that much of the environmental disease burden is attributable to a few critical risk factors which include unsafe water and sanitation, exposure to indoor smoke from cooking fuel, outdoor air pollution, exposure to chemicals such as arsenic, and climate change. Second, that environment and health aspects must become, as a matter of urgency, a national priority, both in terms of policy and resources allocation. To meet the challenge of health and environment now and in the future, the following strategic approaches must be considered which include conducting environmental and health impact assessments; strengthening national environmental health policy and infrastructure; fostering inter-sectoral co-ordination and partnerships; mobilizing public participation; and enhancing the leadership role of health in advocacy, stewardship and capacity building.",
Arsenic,1338810,"Chemical stabilization of metals and arsenic in contaminated soils using oxides - A review Abstract: Oxides and their precursors have been extensively studied, either singly or in combination with other amendments promoting sorption, for in situ stabilization of metals and As in contaminated soils. This remediation option aims at reducing the available fraction of metal(loid)s, notably in the root zone, and thus lowering the risks associated with their leaching, ecotoxicity, plant uptake and human exposure. This review summarizes literature data on mechanisms involved in the immobilization process and presents results from laboratory and field experiments, including the subsequent influence on higher plants and aided phytostabilization. Despite the partial successes in the field, recent knowledge highlights the importance of long-term and large-scale field studies evaluating the stability of the oxide-based amendments in the treated soils and their efficiency in the long-term.",
Arsenic,82367,"Lung cancer risks among lead smelter workers also exposed to arsenic Abstract: Recent publications indicate an increased incidence of lung cancer in non-ferrous smelter workers exposed to lead. The present study provides further data on selected subgroups in one such cohort. The cohort was based on 3979 smelter workers employed for at least 1 year between 1928 and 1979, and also exposed to lead and included in the Blood Lead Register that was started at the smelter in 1950. Two subcohorts were formed from the original cohort. One consists of 710 workers employed at the lead departments (Lead subcohort 1), and the other of 383 workers employed at the lead departments (Lead subcohort 2), but never at other works where an excess lung cancer risk was previously identified. Standardized Cancer Incidence Rates (SIR) 1958-1987 were calculated relative to county rates. In the subcohorts, arsenic exposure in lung cancer cases was assessed in detail based on occupational hygiene information from the company. Lung cancer incidence was raised in both subcohorts (Lead subcohort 1: SIR 2.4; 95% CI 1.2-4.5; Lead subcohort 2: SIR 3.6; 95% CI 1.2-8.3). Total cancer incidence in the cohorts was not increased. A detailed study of arsenic exposure in the 10 lung cancer cases in these two subcohorts revealed that all but one of these cases had a significant exposure also to arsenic. An elevated incidence of lung cancer was observed in smelter workers exposed to lead. However, considerable arsenic exposure also occurred in a majority of the lung cancer cases in the investigated subcohorts. In this multifactorial exposure situation it has not been possible to separate the carcinogenic effects of lead and arsenic, but a possible interaction between these metals may be involved in explaining the carcinogenic risks.",
Arsenic,1797842,"Molecular characterization of Alr1105 a novel arsenate reductase of the diazotrophic cyanobacterium Anabaena sp. PCC7120 and decoding its role in abiotic stress management in Escherichia coli Abstract: This paper constitutes the first report on the Alr1105 of Anabaena sp. PCC7120 which functions as arsenate reductase and phosphatase and offers tolerance against oxidative and other abiotic stresses in the alr1105 transformed Escherichia coli. The bonafide of 40.8 kDa recombinant GST+Alr1105 fusion protein was confirmed by immunoblotting. The purified Alr1105 protein (mw 14.8 kDa) possessed strong arsenate reductase (Km 16.0 ± 1.2 mM and Vmax 5.6 ± 0.31 ?mol min(-1) mg protein(-1)) and phosphatase activity (Km 27.38 ± 3.1 mM and Vmax 0.077 ± 0.005 ?mol min(-1) mg protein(-1)) at an optimum temperature 37 °C and 6.5 pH. Native Alr1105 was found as a monomeric protein in contrast to its homologous Synechocystis ArsC protein. Expression of Alr1105 enhanced the arsenic tolerance in the arsenate reductase mutant E. coli WC3110 (?arsC) and rendered better growth than the wild type W3110 up to 40 mM As (V). Notwithstanding above, the recombinant E. coli strain when exposed to CdCl2, ZnSO4, NiCl2, CoCl2, CuCl2, heat, UV-B and carbofuron showed increase in growth over the wild type and mutant E. coli transformed with the empty vector. Furthermore, an enhanced growth of the recombinant E. coli in the presence of oxidative stress producing chemicals (MV, PMS and H2O2), suggested its protective role against these stresses. Appreciable expression of alr1105 gene as measured by qRT-PCR at different time points under selected stresses reconfirmed its role in stress tolerance. Thus the Alr1105 of Anabaena sp. PCC7120 functions as an arsenate reductase and possess novel properties different from the arsenate reductases known so far.",
Arsenic,1345710,"Inhibition of HSP70 expression by calcium ionophore A23187 in human cells - An effect independent of the acquisition of DNA-binding activity by the heat shock transcription factor Abstract: Heat shock proteins (HSPs) are induced in mammalian cells in a variety of pathophysiological states and have an important role in cytoprotection in vitro and in vivo. In this study, we report that the calcium ionophore A23187, a glucose-regulated protein (GRP) inducer, dramatically inhibits HSP70 synthesis and HSP70 mRNA transcription after induction by heat shock, sodium arsenite, or prostaglandin A1 treatment in human K562 cells. A23187 does not suppress, and it actually prolongs, the DNA-binding activity of the human heat shock transcription factor (HSF), while it alters HSF1 phosphorylation in heat shock-treated cells. To inhibit HSP70 expression, A23187 needs to be present during heat shock, while treatment before or after heat shock does not affect HSP70 mRNA transcription. The GRP inducer thapsigargin, which specifically inhibits the endoplasmic reticulum Ca2+-ATPase, has no effect on heat-induced HSP70 synthesis, indicating that A23187 inhibitory activity is not due to depletion of intracellular calcium stores and is independent of the concomitant induction of GRP genes. Inhibition of HSP70 expression is correlated with alterations in HSF1 phosphorylation in heat-shocked cells, but not in sodium arsenite-treated cells, indicating that different mechanisms may be involved in mediating A23187 inhibitory activity.",
Arsenic,1027720,"Influence of glucose on the toxicity of oxophenylarsine in MDCK cells Abstract: Trivalent arsenicals like oxophenylarsine (PhAsO) inhibit cellular pyruvate dehydrogenase, thus leading to a drop of acetylCoA formation and a slow-down of the citric acid cycle. Glucose may protect cells from arsenic toxicity, because increased glycolysis may prevent fatal shortage of ATP. On the other hand, PhAsO has been shown to inhibit glucose uptake in Madin-Darby canine kidney (MDCK) cells. We have investigated the effect of PhAsO on viability, ATP levels and glucose uptake of MDCK cells in the presence of normal (5 mmol/l) and low (0.01 mmol/l) glucose concentrations. At normal as well as at low glucose concentrations, cell viability as assessed by formazan formation was not affected by PhAsO concentrations up to 2 mumol/l within 3 h of observation. At higher PhAsO concentrations viability was diminished earlier and more pronounced in the presence of low glucose concentrations. 10 mumol/l PhAsO induced a drastic drop of ATP within 30 min which was followed by an almost complete loss of viable cells after 180 min in the presence of low glucose concentrations, while at normal glucose levels no influence on ATP contents or on cell viability was detected within 60 min of incubation. On the other hand, glucose uptake, determined as 14C accumulation by cells incubated for 10 min with D-[6-14C]-glucose, was inhibited by PhAsO at low as well as at normal glucose concentrations in a dose dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,1519055,"XANES evidence of arsenate removal from water with magnetic ferrite Abstract: Arsenic (As) in groundwater and surface water is a worldwide problem possessing a serious threat to public health. In this study, a magnetic ferrite, was synthesized and investigated for its As(V) removal efficiency. The adsorption of As(V) by magnetic ferrite exhibited an L-shaped nonlinear isotherm, suggesting limiting binding sites on the adsorbent surface. The As K-edge X-Ray Absorption Near-Edge Structure (XANES) revealed that the adsorbed As(V) on ferrite was not reduced to more toxic As(III) by Fe(2+) in the ferrite structure. The maximum As adsorption capacity of ferrite was 14 mg/g at pH 3 and decreased with increasing pH due to enhanced electrostatic repulsion between As(V) and the adsorbent surface. Desorption of As(V) using six different acid and salt solutions showed that the desorption rate decreased in an order of H3PO4 &gt; Na3PO4 &gt; H2SO4 &gt; Na2SO4 &gt; HCl &gt; HNO3. These results suggest that magnetic ferrite without surface modification is an effective adsorbent for removing As(V) from water, which was confirmed by the effective removal of As(V) from contaminated groundwater using this material. The used material can then be recovered using a magnet because of its paramagnetism; the adsorbed As(V) on the material can be recovered using H3PO4 or Na3PO4 solutions.",
Arsenic,627029,"Inorganic arsenic compounds cause oxidative damage to DNA and protein by inducing ROS and RNS generation in human keratinocytes Abstract: Arsenic is a naturally occurring element that is present in food, soil, and water. Inorganic arsenic can accumulate in human skin and is associated with increased risk of skin cancer. Oxidative stress due to arsenic exposure is proposed as one potential mode of carcinogenic action. The purpose of this study is to investigate the specific reactive oxygen and nitrogen species that are responsible for the arsenic-induced oxidative damage to DNA and protein. Our results demonstrated that exposure of human keratinocytes to trivalent arsenite caused the generation of 8-hydroxyl-2'-deoxyguanine (8-OHdG) and 3-nitrotyrosine (3-NT) in a concentration- and time-dependent manner. Pentavalent arsenate had similar effects, but to a significantly less extent. The observed oxidative damage can be suppressed by pre-treating cells with specific antioxidants. Furthermore, we found that pre-treating cells with Nomega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), or with 5,10,15,20-tetrakis (N-methyl-4'-pyridyl) porphinato iron (III) chloride (FeTMPyP), a decomposition catalyst of peroxynitrite, suppressed the generation of both 8-OHdG and 3-NT, which indicated that peroxynitrite, a product of the reaction of nitric oxide and superoxide, played an important role in arsenic-induced oxidative damage to both DNA and protein. These findings highlight the involvement of peroxynitrite in the molecular mechanism underlying arsenic-induced human skin carcinogenesis.",
Arsenic,1023467,"Physiological changes and differential gene expression in mummichogs (Fundulus heteroclitus) exposed to arsenic Abstract: Arsenic has been detected as a contaminant in water bodies around the world. Although a number of studies have shown toxicity to adult fish, little is known about its effects on the offspring. However, human epidemiological studies have shown that arsenic increases the number of stillbirths and prematurely born infants. We examined changes in the morphology and gene expression in juvenile mummichogs (Fundulus heteroclitus) whose parents were exposed to 230 ppb arsenic for 10 days immediately prior to spawning. The hatchlings of exposed fish had a 2.8-fold increased incidence of curved or stunted tails. Total RNA from 6-week-old hatchlings, reared in clean water, was used to construct a cDNA subtractive hybridization library. Using this library, we found 13 genes whose expression was altered in the hatchlings as a result of arsenic exposure. We confirmed differential expression by real-time PCR and found significant up-regulation of myosin light chain 2 (4.2-fold), type II keratin (1.5-fold), tropomyosin (3.1-fold) and parvalbumin (3.5-fold) in the hatchlings whose parents were exposed to arsenic. These genes are important during embryogenesis and their differential expression may be linked to the morphological changes observed in the hatchlings.",
Arsenic,2064224,"Effects of As levels on radial oxygen loss and As speciation in rice Abstract: Greenhouse experiment was conducted to examine effects of arsenic (As) on iron plaque formation, radial oxygen loss, As accumulation, and speciation in rice. Three genotypes were grown in soil with three different concentrations of As. The stress of As caused a slight increase of iron plaque formation (P?&gt;?0.05) and a decrease in the rates of radial oxygen loss (ROL; P?&lt;?0.01). The results of As speciation showed that the percentages of DMA increased from 19-28 % to 53-58 %, while the percentages of inorganic As decreased from 53-58 % to 36-42 % with the increasing soil As concentrations, indicating a strong environmental influence on As species in rice grain. The present study showed that elevated soil As may induce As toxicity towards rice plants, leading to the decrease of ROL; environmental factors could influence As methylation or As species transportation. Our study provided useful information on As tolerance and accumulation in rice which may contribute to reducing the health risk posed by As contamination in rice.",
Arsenic,2279059,"HIV infection and its association with an excess risk of clinical fractures and : A nation-wide case-control study Abstract: Background: Different studies have reported an association between HIV infection, antiretroviral therapies, and impaired bone metabolism, but data on their impact on fracture risk are scarce. We studied the association between a clinical diagnosis of HIV infectionand fracture risk. Methods: We conducted a case–control study using data from the Danish National Health Service registries, including 124,655 fracture cases and 373,962 age- and gender-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. Results: A total of 50 (0.40/1000) patients in the fracture group and 52 (0.14/1000) controls had an HIV diagnosis. The risk of any fracture was thus significantly increased among HIV-infected patients (ageand gender-matched OR = 2.89, 95% CI: 1.99 to 4.18). Similarly, significant increases in the risk of hip (OR = 8.99, 95% CI: 1.39 to 58.0), forearm (OR = 3.50, 95% CI: 1.26 to 9.72), and spine fractures (OR = 9.00, 95% CI: 1.39 to 58.1) were observed. Conclusions: HIV infection is associated with an almost 3-fold increase in fracture risk compared with that of age- and gendermatched uninfected patients. HIV patients are also at an almost 9-fold higher risk of hip fracture.",
Arsenic,627384,"Arsenic trioxide produces polymerization of microtubules and mitotic arrest before apoptosis in human tumor cell lines Abstract: Arsenic trioxide (As(2)O(3)) has been found to induce apoptosis in leukemia cell lines and clinical remissions in patients with acute promyelocytic leukemia. In this study, we investigated the cytotoxic effect and mechanisms of action of As(2)O(3) in human tumor cell lines. As(2)O(3) caused inhibition of cell growth (IC(50) range, 3-14 microM) in a variety of human solid tumor cell lines, including four human non-small-cell lung cancer cell lines (H460, H322, H520, H661), two ovarian cancer cell lines (SK-OV-03, A2780), cervical cancer HeLa, and breast carcinoma MCF-7, as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Flow cytometry analysis showed that As(2)O(3) treatment resulted in a time-dependent accumulation of cells in the G(2)/M phase. We observed, using Wright-Giemsa and 4',6-diamidine-2-phenylindole-dihydrochloride staining, that As(2)O(3) blocked the cell cycle in mitosis. In vitro examination revealed that As(2)O(3) markedly promoted tubulin polymerization without affecting GTP binding to beta-tubulin. Immunocytochemical and EM studies of treated MCF-7 cells showed that As(2)O(3) treatment caused changes in the cellular microtubule network and formation of polymerized microtubules. Similar to most anti-tubulin agents, As(2)O(3) treatment induced up-regulation of the cyclin B1 levels and activation of p34(cdc2)/cyclinB1 kinase, as well as Bcl-2 phosphorylation. Furthermore, activation of caspase-3 and -7 and cleavage of poly(ADP-ribose) polymerase and beta-catenin occurred only in As(2)O(3)-induced mitotic cells, not in interphase cells, suggesting that As(2)O(3)-induced mitotic arrest may be a requirement for the activation of apoptotic pathways. In addition, As(2)O(3) exhibited similar inhibitory effects against parental MCF-7, P-glycoprotein-overexpressing MCF-7/doxorubicin cells, and multidrug resistance protein (MRP)-expressing MCF-7/etoposide cells (resistance indices, 2.3 and 1.9, respectively). Similarly, As(2)O(3) had similar inhibitory effect against parental ovarian carcinoma A2780 cells and tubulin mutation paclitaxel-resistant cell lines PTx10 and PTx22 (resistance indices, 0.86 and 0.93, respectively), suggesting that its effect on tubulin polymerization and G(2)/M phase arrest is distinct from that of paclitaxel. Taken together, our data demonstrate that As(2)O(3) has a paclitaxel-like effect, markedly promotes tubulin polymerization, arrests cell cycle at mitosis, and induces apoptosis. In addition, As(2)O(3) is a poor substrate for transport by P-glycoprotein and MRP, and non-cross-resistant with paclitaxel resistant cell lines due to tubulin mutation, suggesting that As(2)O(3) may be useful for treatment of human solid tumors, particularly in patients with paclitaxel resistance.",1
Arsenic,1352061,Renewable Resource-Based Magnetic Nanocomposites for Removal and Recovery of Phosphorous from Contaminated Waters Abstract: ,
Arsenic,1340101,"Environmental assessment of trace element bioaccumulation in sipunculan from seagrass and wetland sediments Abstract: This study is the first measurement of trace elements in sipunculan and their surrounding sediments. The bioaccumulation characteristics of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) were analyzed and compared in two sipunculan species, Sipuncula nudus and Siphonosoma vastum, which were collected from seagrass beds and wetlands in Taiwan. The sipunculan and sediment samples were analyzed using an inductively coupled plasma mass spectrometer. Both sipunculan in the wetlands and seagrass beds had a high Cu bioaccumulation mechanism. Multivariate analysis, principle component analysis, and partial least squares for discriminant analysis of trace element levels and bioaccumulation factors were used to distinguish the element distributions that corresponded to the two habitats (seagrass beds and wetlands). Different levels of certain trace elements in these two sipunculan species may result not only from the environmental factors of various habitats but also from the accumulation characteristics of various species. The As, Cd, Cr, Cu, Hg, and Zn concentrations were markedly lower in sipunculan than in other invertebrates from the adjacent polluted regions. The public health issues regarding the consumption of sipunculan are also discussed.",
Arsenic,627147,"Combined efficacies of dl-?-lipoic acid and meso 2,3 dimercaptosuccinic acid against arsenic induced toxicity in antioxidant systems of rats Abstract: Health hazards caused by heavy metals have become a great concern to the population. Arsenic as an environmental agent is considered to be a toxic substance due to its carcinogenic potential in humans. Since arsenic compounds might exert their toxicity by the generation of reactive oxygen species, we have evaluated the effect of both DL-alpha-lipoic acid (LA) and meso 2,3 dimercapto succinic acid (DMSA) on the antioxidants and lipid peroxidation in arsenic treated rats. The objective of the study was to determine whether DL-alpha-lipoic acid and meso 2,3 dimercapto succinic acid could rehabitate antioxidant depletion and damage to biomolecules in protection against oxidative insults. A significant increase in the levels of reactive oxygen species formation and lipid peroxidation and decrease in the activities of antioxidant enzymes were observed in arsenic exposed rats. Supplementation of DL-alpha-lipoic acid and meso 2,3 dimercapto succinic acid to arsenic fed rats significantly increased the activities of superoxide dismutase, catalase, glutathione peroxidase with elevation in the levels of reduced glutathione, total sulfhydryl, ascorbic acid and alpha-tocopherol. In addition, significant decrease in the levels of reactive oxygen species formation and lipid peroxidation was also observed in our study. From our results, we conclude that DL-alpha-lipoic acid and meso 2,3 dimercapto succinic acid play a synergistic role in decreasing arsenic induced oxidative damage by elevating the antioxidant status in liver and kidney.",
Arsenic,628769,"EGF receptor-dependent JNK activation is involved in arsenite-induced p21Cip1/Waf1 upregulation and endothelial apoptosis Abstract: Arsenic exposure is associated with an increased risk of atherosclerosis and vascular diseases. Although endothelial cells have long been considered to be the primary targets of arsenic toxicity, the underlying molecular mechanism remains largely unknown. In this study, we sought to explore the signaling pathway triggered by sodium arsenite and its implication for endothelial phenotype. We found that sodium arsenite produced time- and dose-dependent decreases in human umbilical vein endothelial cell viability. This effect correlated with the induction of p21Cip1/Waf1 (up to 10-fold), a regulatory protein of cell cycle and apoptosis. We also found that arsenite-stimulated EGF (ErbB1) and ErbB2 receptor transactivation, manifest as receptor tyrosine phosphorylation, appeared to be a proximal signaling event leading to p21Cip1/Waf1 induction, because both pharmacological inhibitors and knockdown of receptors by RNA interference blocked arsenite-induced p21Cip1/Waf1 upregulation. Arsenite-induced activation of JNK and p38 MAPK was distinct, with only JNK as a downstream target of the EGF receptor. Moreover, inhibition of JNK with SP-600125 or dominant negative MKK7 inhibited only p21Cip1/Waf1 induction, whereas the p38 MAPK inhibitor SB-203580 or dominant negative MKK4 inhibited both p21Cip1/Waf1 and p53 induction. Functionally, inhibition of p21Cip1/Waf1 induction prevented endothelial apoptosis due to arsenite treatment. Insofar as endothelial dysfunction promotes vascular disease, these data provide a mechanism for the increased incidence of cardiovascular disease due to arsenite exposure.",
Arsenic,1337708,"Competitive biosorption of lead, cadmium, copper, and arsenic ions using algae Abstract: The present study aims to evaluate the competitive biosorption of lead, cadmium, copper, and arsenic ions by using native algae. A series of experiments were carried out in a batch reactor to obtain equilibrium data for adsorption of single, binary, ternary, and quaternary metal solutions. The biosorption of these metals is based on ion exchange mechanism accompanied by the release of light metals such as calcium, magnesium, and sodium. Experimental parameters such as pH, initial metal concentrations, and temperature were studied. The optimum pH found for removal were 5 for Cd(2+) and As(3+) and 3 and 4 for Pb(2+) and Cu(2+), respectively. Fourier transformation infrared spectroscopy analysis was used to find the effects of functional groups of algae in biosorption process. The results showed that Pb(2+) made a greater change in the functional groups of algal biomass due to high affinity to this metal. An ion exchange model was found suitable for describing the biosorption process. The affinity constants sequence calculated for single system was K (Pb) &gt; K (Cu) &gt; K (Cd) &gt; K (As); these values reduced in binary, ternary, and quaternary systems. In addition, the experimental data showed that the biosorption of the four metals fitted well the pseudo-second-order kinetics model.",
Arsenic,1032544,"Blackfoot disease in Taiwan: A 30-year follow-up study Abstract: Blackfoot disease is an endemic peripheral vascular disease found among the inhabitants of a limited area on the southwest coast of Taiwan, where artesian well water with a high concentration of arsenic has been used for more than eighty years. The natural history of blackfoot disease, based on a prospective study of 1,300 patients, is presented. The overall male/female ratio was 1.5:1. Although the clinical onset was usually insidious, it may be quite sudden and almost always begins with numbness or coldness in one or more extremities, usually the feet. Ultimately, rest pain develops and progresses to gangrene. In this series, 68% of the patients underwent spontaneous or operative amputation, and the reamputation rate was 23.3%. Lower extremity involvement in blackfoot disease was observed in 97.7% of the cases. The average annual rate for major amputation was 3.81 per 100 patient-years. The factors influencing the prognosis, such as amputation in relation to age and disease onset, are analyzed. The case fatality rate was 66.5% during thirty years; 44% of these were cardiovascular deaths. The annual death rate was 4.84 per 100 patient-years. Other reported case fatality rates for vascular insufficiency are reviewed. A dose-response relationship between blackfoot disease and the duration of water intake was also noted. The survival rates after the onset of blackfoot disease were: five years, 76.0%; ten years, 59.5%; twenty years, 38.2%; thirty years, 28.6%. The 50% survival point was 13.5 years after onset of the disease.",
Arsenic,1019175,"Derivatization of phytochelatins from Silene vulgaris, induced upon exposure to arsenate and cadmium: comparison of derivatization with Ellman's reagent and monobromobimane Abstract: Phytochelatins (PCs) are a family of thiol-rich peptides, with the general structure (gamma-Glu-Cys)(n)()-Gly, with n = 2-11, induced in plants upon exposure to excessive amounts of heavy metals and some metalloids, such as arsenic. Two types of PC analyses are currently used, i.e., acid extraction and separation on HPLC with either precolumn derivatization (pH 8.2) with monobromobimane (mBBr) or postcolumn derivatization (pH 7.8) with Ellman's reagent [5, 5'-dithiobis(2-nitrobenzoic acid), DTNB]. Although both methods were satisfactory for analysis of Cd-induced PCs, formation of (RS)(3)-As complexes during extraction of As-induced PCs rendered the DTNB method useless. This paper shows that precolumn derivatization with mBBr, during which the (RS)(3)-As complexes are disrupted, provides a qualitative and quantitative analysis of both Cd- and As-induced PCs. In addition, derivatization efficiencies of both methods for the oligomers with n = 2-4 (PC(2)(-)(4)) are compared. Derivatization efficiency decreased from 71.8% and 81.4% for mBBr and DTNB derivatization, respectively, for PC(2) to 27.4% and 50.2% for PC(4). This decrease is most likely due to steric hindrance. Correction of measured thiol concentration is therefore advised for better quantification of PC concentrations in plant material.",
Arsenic,1015732,"Impact on arsenic exposure of a growing proportion of untested wells in Bangladesh Abstract: BACKGROUND: In many areas of Bangladesh, it has been more than six years since a national campaign to test tubewells for arsenic (As) was conducted. Many households therefore draw their water for drinking and cooking from untested wells. METHODS: A household drinking water survey of 6646 households was conducted in Singair upazilla of Bangladesh. A subset of 795 untested wells used by 1000 randomly selected households was tested in the field by trained village workers with the Hach EZ kit, using an extended reaction time of 40 min, and in the laboratory by high-resolution inductively-coupled plasma-mass spectrometry (HR ICP-MS). RESULTS: The household survey shows that more than 80% of the wells installed since the national testing campaign in this area were untested. Less than 13% of the households with untested wells knew where a low-As well was located near their home. Village workers using the Hach EZ kit underestimated the As content of only 4 out of 795 wells relative to the Bangladesh standard. However, the As content of 168 wells was overestimated relative to the same threshold. CONCLUSION: There is a growing need for testing tubewells in areas of Bangladesh where As concentrations in groundwater are elevated. This could be achieved by village workers trained to use a reliable field kit. Such an effort would result in a considerable drop in As exposure as it increases the opportunities for well switching by households.",
Arsenic,2278605,"A Visual Basic simulation software tool for performance analysis of a membrane-based advanced water treatment plant Abstract: A Visual Basic simulation software (WATTPPA) has been developed to analyse the performance of an advanced wastewater treatment plant. This user-friendly and menu-driven software is based on the dynamic mathematical model for an industrial wastewater treatment scheme that integrates chemical, biological and membrane-based unit operations. The software-predicted results corroborate very well with the experimental findings as indicated in the overall correlation coefficient of the order of 0.99. The software permits pre-analysis and manipulation of input data, helps in optimization and exhibits performance of an integrated plant visually on a graphical platform. It allows quick performance analysis of the whole system as well as the individual units. The software first of its kind in its domain and in the well-known Microsoft Excel environment is likely to be very useful in successful design, optimization and operation of an advanced hybrid treatment plant for hazardous wastewater.",
Arsenic,1355014,"p70 S6 kinase is activated by sodium arsenite in adult rat cardiomyocytes: Roles for phosphatidylinositol 3-kinase and p38 MAP kinase Abstract: p70 S6 kinase (p70 S6k) is important in regulating a variety of cellular functions including mRNA translation and cell cycle progression and is activated by mitogens and hormones. Unexpectedly, we have found that, in adult rat cardiomyocytes, arsenite, which generally induces stress responses, markedly and rapidly activates p70 S6k. This activation of p70 S6k is completely blocked by rapamycin but only partially prevented by inhibitors of phosphatidylinositol 3-kinase. In trying to delineate the mechanism underlying this effect, we found that arsenite did not activate protein kinase B, JNK or MAP kinase, but did activate p38 MAP kinase in cardiac myocytes. A specific inhibitor of p38 MAP kinase (SB203580) partially attenuated the stimulation of p70 S6k by arsenite. These data indicate that the activation of p70 S6k by arsenite involves p38 MAP kinase and phosphatidylinositol 3-kinase but not PKB.",
Arsenic,627810,"Distribution of gamma-tubulin in multipolar spindles and multinucleated cells induced by dimethylarsinic acid, a methylated derivative of inorganic arsenics, in Chinese hamster V79 cells Abstract: Localization of gamma-tubulin, a well-characterized component of microtubule-organizing centers (MTOCs), was investigated because of interest in the mechanism of the induction of aberrant mitotic spindles in Chinese hamster V79 cells exposed to dimethylarsinic acid (DMAA). In control cultures, gamma-tubulin in interphase cells was located as a perinuclear dot on which the microtubules were nucleated. In metaphase cells, the location of gamma-tubulin coincided with that of the mitotic spindle poles. DMAA caused mitotic delay and aberrant spindles, such as tripolar- and quadripolar spindles, in the mitotic cells. Gamma-tubulin was co-localized with the aberrant spindles induced by DMAA. The incidence of gamma-tubulin in the mitotic cells coincided with that of the aberrant spindles and rose with an increasing concentration of DMAA. By contrast, DMAA did not influence the number and location of gamma-tubulin signals in interphase cells. These results suggest that multiple microtubule nucleation sites were induced by DMAA during transition from interphase to mitotic phase. DMAA-induced multiple signals of gamma-tubulin were integrated into one signal at the center of multinucleated cells, surrounded by multiple nuclei as the cell cycle progressed to the next interphase, suggesting the presence of a self-integration mechanism of centrosomal MTOCs during the cell cycle.",
Arsenic,1339187,"Co-occurrence of arsenic and fluoride in groundwater of semi-arid regions in Latin America: Genesis, mobility and remediation Abstract: Several million people around the world are currently exposed to excessive amounts of arsenic (As) and fluoride (F) in their drinking water. Although the individual toxic effects of As and F have been analyzed, there are few studies addressing their co-occurrences and water treatment options. Several studies conducted in arid and semi-arid regions of Latin America show that the co-occurrences of As and F in drinking water are linked to the volcaniclastic particles in the loess or alluvium, alkaline pH, and limited recharge. The As and F contamination results from water-rock interactions and may be accelerated by geothermal and mining activities, as well as by aquifer over-exploitation. These types of contamination are particularly pronounced in arid and semi-arid regions, where high As concentrations often show a direct relationship with high F concentrations. Enrichment of F is generally related to fluorite dissolution and it is also associated with high Cl, Br, and V concentrations. The methods of As and F removal, such as chemical precipitation followed by filtration and reverse osmosis, are currently being used at different scales and scenarios in Latin America. Although such technologies are available in Latin America, it is still urgent to develop technologies and methods capable of monitoring and removing both of these contaminants simultaneously from drinking water, with a particular focus towards small-scale rural operations.",
Arsenic,1031491,"Microprobe XRF mapping and XAS investigations of the intracellular metabolism of arsenic for understanding arsenic-induced toxicity Abstract: Arsenic (As) is responsible for mass-poisonings worldwide following the ingestion of As-contaminated drinking water. Importantly, however, As toxicity is exploited in the antileukemia drug, Trisenox (As2O3), which successfully cures 65-80% of patients suffering relapsed acute promyelocytic leukemia. In an effort to determine the intracellular organelle and biomolecular targets of As, microprobe X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XAS) analyses were performed on HepG2 cells following their exposure to high doses of arsenite (1 mM) or arsenate (20 mM). Microprobe XRF elemental mapping of thin-sectioned cells showed As accumulation in the euchromatin region of the cell nucleus (following arsenite exposure) synonymous with As targeting of DNA or proteins involved in DNA transcription. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) analysis of arsenite-treated cells, however, showed the predominance of an As tris-sulfur species, providing increased credence to As interactions with nuclear proteins as a key factor in As-induced toxicity.",
Arsenic,1015710,"Arsenic toxicity: A heart-breaking saga of a freshwater mollusc Abstract: The freshwater wetland systems of India is a complex habitat that supports a broad range of diverse species including molluscs, which play an important role in supplementing third world countries. In the arsenic affected flood plains of West Bengal, a huge amount of arsenic laden groundwater is raised for the purpose of irrigation. Agricultural runoffs and flood water movement during monsoon may cause accumulation of arsenic in the adjacent freshwater aquifers, the common habitat of Lamellidens marginalis (Mollusca; Bivalvia; Eulamellibranchiata), a filter feeder, sensitive to altered environmental conditions. To examine the nature of toxicity induced by inorganic arsenic on both the haemocytes and tissues of the invertebrate heart, the animals were exposed to five different sublethal concentrations of sodium arsenite for a maximum time span of 30 days in vitro. Significant differences were recorded in the total haemocyte count, biochemical and histopathological parameters of the heart of L. marginalis under the arsenic induced stress. Our observations indicate the development of profound haematopoietic and cardiac stress under the sublethal inorganic arsenite exposure and it also implies the nature of risk imposed on the freshwater aquatic ecosystem under potential arsenic contamination.",
Arsenic,471981,"Comparison of the mutagenic potential of 17 physical and chemical agents analyzed by the flow cytometry mutation assay Abstract: Several methods to assess genotoxicity of physical and chemical agents have been developed, most of which depend on growing colonies in selective medium. We recently published a new method for detecting mutations in the CD59 gene in a Chinese hamster ovary cell line that contains a single copy of human chromosome 11 (CHO A(L)). The assay is based on detecting the surface expression of CD59 with monoclonal antibodies using flow cytometry. The capabilities of this flow cytometry mutation assay (FCMA) to detect mutations from a wide variety of genotoxic agents are described here. There was a 400-fold separation between CD59(-) and CD59(+) populations based on fluorescence intensity. Small numbers of negative cells mixed in with positive cells were detected in a highly linear fashion. Mutation dose response curves over a dose range yielding 80% to 20% survival are shown for ethyl methane sulfonate (EMS), mitomycin C (MMC) and lead acetate. EMS and lead acetate exhibited a threshold in response while MMC had a linear dose response over the full dose range. The mutant fraction was measured over time periods ranging up to 35 days following treatment. The mutant fraction peaked at different times ranging from 6 to 12 days after treatment. An additional 14 chemical and physical agents including point mutagens, heavy metals, ionizing and UV radiation, and DNA intercalators and cross linkers, were analyzed for mutagenic potential after doses giving 80% to 20% survival. The results presented here demonstrate the sensitivity and broad-ranging capability of the FCMA to detect mutations induced by a variety of genotoxic agents. Published by Elsevier B.V.",
Arsenic,1019723,"Urinary excretion of arsenic species after exposure to arsenic present in drinking water Abstract: The water from some drilled wells in southwest Finland contains high arsenic concentrations (min-max: 17-980 microg/L). We analyzed inorganic arsenic (As-i) and organic arsenic (monomethylarsonate [MMA] and dimethylarsinate [DMA]) species in urine and conducted a clinical examination of current users (n = 35) and ex-users (n = 12) of such wells. Ex-users had ceased to use the water from the wells 2-4 months previously. Urinary arsenic species were also analyzed from persons whose drinking water contained less than 1 microg/L of arsenic (controls, n = 9). The geometric means of the concentrations of total arsenic in urine were 58 microg/L for current users, 17 microg/L for ex-users, and 5 microg/L for controls. The excreted arsenic was associated with the calculated arsenic doses, and on average 63% of the ingested arsenic dose was excreted in urine. The ratios of MMA/DMA and As-i/As-tot (As-tot = As-i + MMA + DMA) in urine tended to be lower among the current users and in the higher exposure levels than in controls, suggesting that As-i was better methylated in current users. However, the differences were mainly explained by age; older persons were better methylators of inorganic arsenic than younger individuals. The arsenic content of hair correlated well with the past and chronic arsenic exposure; an increase of 10 microg/L in the arsenic concentration of the drinking water or an increase of 10-20 microg/day of the arsenic exposure corresponded to a 0.1 mg/kg increase in hair arsenic. The individuals were interviewed and complained of muscle cramps, mainly in the legs, and this was associated with elevated arsenic exposure. The present study demonstrates that arsenic methylation has no threshold at these exposure levels.",
Arsenic,2337135,"REMOVAL OF As (V) AND As(III) FROM WATER USING Mn-DOPED MAGHEMITE NANOPARTICLES Abstract: Although nano-adsorbents often show better adsorptive properties, they suffer from the difficulties to be separated from water. Magnetic separation is an efficient process to separate magnetic solids from water. It will be interesting to prepare magnetic nanoparticles as adsorbent for pollutant removal, which combines advantages of better adsorption capacity and easy separation using magnetic process. In this study, a novel nano magnetic adsorbent, Mn-doped maghemite, was developed. The prepared adsorbent can be separated efficiently using magnetic separation process. The adsorbent was characterized and the results showed that the nano-adsorbent with a high specific surface area (133.9m(2)/g) was part amorphous. Iron and manganese existed mainly in the oxidation state of +III and +square, respectively. The adsorbent showed excellent adsorption towards As(V) and As(III) and they showed significantly higher adsorption capacity for As(III) than As(V). The adsorption fits Langmuir isotherm well and the calculated As(V) and As(III) maximum adsorption capacity was 14.97 mg/g and 22.59 mg/g respectively, at pH 7.0. Coexisting ions have different kinds of effects on arsenic removal. Phosphate was the greatest competitor with arsenic for adsorptive sites on the adsorbent, while Ca2+, Mg2+ enhanced the adsorption capacity of the adsorbent for As(V).",
Arsenic,1677388,"Trace metal source terms in carbon sequestration environments Abstract: Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO(2) or CO(2)-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO(2). Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs by an order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality.",
Arsenic,1021539,"Overabundance of putative cancer stem cells in human skin keratinocyte cells malignantly transformed by arsenic Abstract: Arsenic is a human skin carcinogen. Cancer is probably a disease driven by stem cells (SCs), and SCs are likely a key target during arsenic oncogenesis. In utero arsenic exposure predisposes mice to skin cancers that overproduce cancer SCs (CSCs) and have distorted CSC signaling and population dynamics. Therefore, we hypothesized CSC accumulation may occur during arsenic-induced malignant transformation in vitro of human skin keratinocytes. Thus, the HaCaT cell line, malignantly transformed by arsenite (100 nM, 30 weeks; termed As-TM cells) in prior work, was further studied for the quantity and nature of SCs after this transformation. SCs were isolated from passage-matched control and As-TM cells by a magnetic bead system that enriches for CD34-positive cells. There were 2.5 times more SCs isolated from As-TM cells than control. Holoclone production from As-TM putative CSCs was 2.5-fold higher by 1 week and 3.5-fold higher by 2 weeks than control SCs. Potential malignant phenotype was assessed in isolated SC/CSCs. Transcript level of SC/CSC markers were elevated in both isolated As-TM CSCs and control SCs compared with parental cells, but compared with control SCs, As-TM putative CSCs had elevated CD34, K5, K14, K15, and K19 transcripts and dramatically stronger staining for p63, Rac1, K5, Notch1, and K19. As-TM putative CSCs also showed markedly elevated MMP-9 secretion and colony formation, indicators of cancer phenotype, even compared with total population of As-TM cells. Thus, malignant phenotype is particularly pronounced in CSCs after arsenic-induced transformation of human skin cells and occurs concurrently with a potential overproduction of these cells.",
Arsenic,656836,"The role of oxidative DNA damage in human arsenic carcinogenesis: Detection of 8-hydroxy-2'-deoxyguanosine in arsenic-related Bowen's disease Abstract: Arsenic is widely distributed in nature in the form of either metalloids or chemical compounds, which cause a variety of pathologic conditions including cutaneous and visceral malignancies. Recently, reactive oxygen species have been hypothesized to be one of the causes of arsenic-induced carcinogenesis. 8-Hydroxy-2'-deoxyguanosine is one of the major reactive oxygen species-induced DNA base-modified products that is widely accepted as a sensitive marker of oxidative DNA damage. We studied the presence of 8-hydroxy-2'-deoxyguanosine by immunohistochemistry using N45.1 monoclonal antibody in 28 cases of arsenic-related skin neoplasms and arsenic keratosis as well as in 11 cases of arsenic-unrelated Bowen's diseases. The frequency of 8-hydroxy-2'-deoxyguanosine positive cases was significantly higher in arsenic-related skin neoplasms (22 of 28; 78%) than in arsenic-unrelated Bowen's disease (one of 11; 9%) (p < 0.001 by chi2 test). 8-Hydroxy-2'-deoxyguanosine was also detected in normal tissue adjacent to the arsenic-related Bowen's disease lesions. Furthermore, arsenic was detected by neutron activation analysis in the deparaffined skin tumor samples of arsenic-related disease (four of five; 80%), whereas arsenic was not detected in control samples. Our results strongly suggest the involvement of reactive oxygen species in arsenic-induced human skin cancer. Key word: neutron activation analysis.",
Arsenic,1597423,"Proteomic and metabolomic responses of clam Ruditapes philippinarum to arsenic exposure under different salinities Abstract: Arsenic (As) contamination is a severe problem in the intertidal zones of the Bohai Sea (China) with wide salinity variation. In the present study, we combined proteomics and metabolomics to characterize the differential responses of arsenic in clam Ruditapes philippinarum under different salinities (31.1, 23.3 and 15.6psu). Both proteomic and metabolomic responses indicated that varying salinities could significantly affect the toxicological responses of clams to As. Metabolic biomarkers revealed that the environmentally relevant arsenic (20?gL(-1)) exposure induced disturbance in energy metabolism and/or osmotic regulation under different salinities, whereas protein biomarkers indicated oxidative stress, cellular injury and apoptosis and disturbance in energy metabolism. In addition, the up-regulated proteins including ATP synthase, succinyl-CoA synthetase and nucleoside diphosphate kinase were validated by related metabolites, succinate and ATP, which confirmed the disturbance in energy metabolism in clam gills at low salinity (15.6psu). These findings provide important insights into toxicological effects of environmental contaminant at molecular levels using combined proteomics and metabolomics.",
Arsenic,627939,"Biomarkers of exposure, effect, and susceptibility of arsenic-induced health hazards in Taiwan Abstract: Long-term exposure to inorganic arsenic from drinking water has been documented to induce cancers and vascular diseases in a dose-response relationship. A series of molecular environmental epidemiological studies have been carried out to elucidate biomarkers of exposure, effect, and susceptibility for arsenic-related health hazards in Taiwan. Arsenic levels in urine, hair, and nail are biomarkers for short-term (<1 year) internal dose, skin hyperpigmentation and palmoplantar hyperkeratosis are for long-term (many years) internal dose, and percentage of monomethylarsonic acid in total metabolites of inorganic arsenic in urine may be considered as an exposure marker for biologically effective dose. The biomarkers of early biological effects of ingested inorganic arsenic included blood levels of reactive oxidants and anti-oxidant capacity, genetic expression of inflammatory molecules, as well as cytogenetic changes including sister chromatid exchange, micronuclei, and chromosome aberrations of peripheral lymphocytes. Both mutation type and hot spots of p53 gene were significantly different in arsenic-induced and non-arsenic-induced TCCs. The frequency of chromosomal imbalances analyzed by comparative genomic hybridization and the frequency of loss of heterozygosity were significantly higher in arsenic-induced TCC than non-arsenic-induced TCC at specific sites. Biomarkers of susceptibility to arsenic-induced health hazards included genetic polymorphisms of enzymes involved in xenobiotic metabolism, DNA repair, and oxidative stress, as well as serum level of carotenoids. Gene-gene and gene-environment interactions are involved in arsenic-induced health hazards through toxicological mechanisms including genomic instability and oxidative stress.",
Arsenic,1019590,"Enzymatic methylation of arsenic compounds. VI. Characterization of hamster liver arsenite and methylarsonic acid methyltransferase activities in vitro Abstract: Methylation of inorganic arsenic to methylarsonic acid (MMA) and dimethylarsinic acid (DMA) has been considered to be the major pathway of inorganic arsenic biotransformation and detoxification. Comparative studies, in vivo, have demonstrated variation in the abilities of animals to methylate inorganic arsenic. We propose that the rate of inorganic arsenite methylation may be one of the factors responsible for observed species variation. Arsenite and MMA methyltransferases of Golden Syrian hamster liver have been partially purified 40- and 67-fold, respectively. The monothiol L-cysteine promotes greater activities, in vitro, of these enzymes than similar concentrations of either glutathione or dithiothreitol. The pH optima of the partially purified arsenite and MMA methyltransferase activities are 7.6 and 8.0, respectively. Both activities display classic Michaelis-Menten enzyme kinetics. The K(m) and Vmax of hamster liver arsenite methyltransferase are 1.79 x 10(-6) M and 0.022 pmol/mg protein/60 min, respectively. Hamster liver MMA methyltransferase has K(m) and Vmax values of 7.98 x 10(-4) M and 0.007 pmol/mg protein/60 min, respectively. A similar kinetic relationship of these activities is also observed in the liver of the rabbit, which, like the hamster, excretes higher amounts of MMA than most other species studied. The higher K(m) and lower Vmax of MMA methyltransferase, compared to arsenite methyltransferase, measured in these two species suggests that MMA may be produced at a rate higher than it can be subsequently methylated to DMA, thereby allowing MMA to accumulate and be excreted.",
Arsenic,1032278,"Induction of metallothionein by arsenicals in mice Abstract: Metallothionein (MT) is a sulfhydryl-rich, metal-binding protein that provides protection against metal toxicity. MT is induced by acute stress, hormones, metals, and various organic compounds. Recently, arsenicals have also been shown to induce MT. However, the mechanism and character of MT induction by arsenicals is unknown. Therefore, the effect of various arsenic forms on the tissue concentration of MT was determined. Mice were injected sc with various doses of arsenite [As(III)], arsenate [As(V)], monomethylarsenate (MMAA), and dimethylarsenate (DMAA), and MT content in the liver was measured 24 hr later by the Cd-hemoglobin radioassay. As(III) is a potent hepatic MT inducer in that a 30-fold increase in MT was observed at the dose of 85 mumol/kg. In comparison, it took 3-, 50-, and 120-fold higher molar amounts of As(V), MMAA, and DMAA, respectively to produce a similar effect. MMAA produces the largest increase in hepatic MT (80-fold), followed by As(III) (30-fold), As(V) (25-fold), and DMAA (10-fold). However, none of the arsenicals induced MT in mouse primary hepatocyte cultures. Both MT-I and MT-II were coordinately induced by As(III), As(V), and MMAA. MT induction by As(III) was further characterized following sc administration of arsenite (85 mumol/kg). Hepatic MT induction peaked at 24 hr, and in addition to the liver, As(III) also increased MT in kidney, spleen, stomach, intestine, heart, and lung. MT-I mRNA increased 24-, 52-, and 11-fold at 3, 6, and 15 hr after As(III) administration. This induction profile is similar to that observed after Zn or Cd exposure.(ABSTRACT TRUNCATED AT 250 WORDS)",1
Arsenic,2337085,"Influence of moderate pre-oxidation treatment on the physical, chemical and phosphate adsorption properties of iron-containing activated carbon Abstract: A novel adsorbent based on iron oxide dispersed over activated carbon (AC) were prepared, and used for phosphate removal from aqueous solutions. The influence of pre-oxidation treatment on the physical, chemical and phosphate adsorption properties of iron-containing AC were determined. Two series of ACs, non-oxidized and oxidized carbon modified by iron (denoted as AC-Fe and AC/O-Fe), resulted in a maximum impregnated iron of 4.03% and 7.56%, respectively. AC/O-Fe showed 34.0%-46.6% higher phosphate removal efficiency than the AC-Fe did. This was first attributed to the moderate pre-oxidation of raw AC by nitric acid, achieved by dosing Fe(II) after a pre-oxidation, to obtain higher iron loading, which is favorable for phosphate adsorption. Additionally, the in-situ formed active site on the surface of carbon, which was derived from the oxidation of Fe(II) by nitric acid dominated the remarkably high efficiency with respect to the removal of phosphate. The activation energy for adsorption was calculated to be 10.53 and 18.88 kJ/mol for AC-Fe and AC/O-Fe, respectively. The results showed that the surface mass transfer and intra-particle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism.",
Arsenic,2149283,Heterologous Expression of a Carrot Small Heat Shock Protein Increased Escherichia coli Viability under Lead and Arsenic Stresses Abstract: ,
Arsenic,1032565,"Effects of nickel sulfate, lead sulfate, and sodium arsenite alone and with UV light on sister chromatid exchanges in cultured human lymphocytes Abstract: Sister chromatid exchanges (SCE) have been examined in human lymphocytes following in vitro treatments with metal salts, nickel sulfate, lead sulfate and sodium arsenite. All of the metal salts produced significant increases in the SCE frequencies over the levels for untreated lymphocytes. The SCE frequencies were also examined for metal treatments combined with ultraviolet light (200 ergs/mm2). For the lead treatments combined with the UV dose selected, an additive SCE response was observed compared to the SCE responses for UV or metal alone. The nickel and arsenite treatments combined with UV produced a less than additive SCE response for most concentrations tested. These results suggest that nickel or arsenite present in complex mixtures may reduce the SCE response to other compounds in the mixture normally capable of producing a much stronger SCE response and therefore lead to an underestimate of the effects of chemical exposure.",
Arsenic,627027,"The MRP2/cMOAT transporter and arsenic-glutathione complex formation are required for biliary excretion of arsenic Abstract: Worldwide, millions of people are exposed to arsenic in drinking water that exceeds the World Health Organization standard of 10 microg/liter by as much as 50-300-fold, yet little is known about the molecular basis for arsenic excretion. Here we show that transport of arsenic into bile depends on the MRP2/cMOAT transporter and that glutathione is obligatory for such transport. Using reversed phase liquid chromatography/mass spectrometry, we demonstrate that two arsenic-glutathione complexes not previously identified in vivo, arsenic triglutathione and methylarsenic diglutathione, account for most of the arsenic in the bile. The structure of the compounds was also confirmed by nuclear magnetic resonance spectroscopy. Our findings may help explain the increased susceptibility of malnourished human populations to arsenic.",
Arsenic,1579290,"Protective effects of selenium on oxidative damage and oxidative stress related gene expression in rat liver under chronic poisoning of arsenic Abstract: Arsenic (As) is a toxic metalloid existing widely in the environment, and chronic exposure to it through contaminated drinking water has become a global problem of public health. The present study focused on the protective effects of selenium on oxidative damage of chronic arsenic poisoning in rat liver. Rats were divided into four groups at random and given designed treatments for 20weeks. The oxidative damage of liver tissue was evaluated by lipid peroxidation and antioxidant enzymes. Oxidative stress related genes were detected to reflect the liver stress state at the molecular level. Compared to the control and Na2SeO3 groups, the MDA content in liver tissue was decreased and the activities of antioxidant enzymes were increased in the Na2SeO3 intervention group. The mRNA levels of SOD1, CAT, GPx and Txnrd1 were increased significantly (P&lt;0.05) in the combined Na2SeO3+NaAsO2 treatment group. The expressions of HSP70 and HO-1 were significantly (P&lt;0.05) increased in the NaAsO2 group and reduced in the combined treatment group. The results indicate that long-term intake of NaAsO2 causes oxidative damage in the rat liver, and Na2SeO3 protects liver cells by adjusting the expression of oxidative stress related genes to improve the activities of antioxidant enzymes.",
Arsenic,710830,"Arsenic induces mitochondria-dependent apoptosis by reactive oxygen species generation rather than glutathione depletion in Chang human hepatocytes Abstract: This study was conducted to evaluate the possible involvement of mitochondrial pathway in NaAsO2-induced apoptosis and the role of reactive oxygen species (ROS) and reduced glutathione (GSH) in the apoptotic effect in Chang human hepatocytes. The MTT assay demonstrated that sodium arsenite (NaAsO2) treatment for 24 h caused a dose-dependent decrease of cell viability. NaAsO2 treatment (0-30 microM) was also found to induce phosphatidylserine externalization, a hallmark of apoptosis; to disrupt the mitochondrial membrane potential (Deltapsi ( m )); to cause the release of cytochrome c into the cytosol, and to trigger cleavage of caspase-3 and poly (ADP-ribose) polymerase (PARP) in a dose-dependent manner. All these changes were accompanied with the enhanced generation of intracellular ROS and malondialdehyde (MDA). Increase of intracellular GSH also coincided unexpectedly. Moreover, the extracellular addition of N-acetyl-L-cysteine (NAC, 5 mM) effectively reduced the generation of ROS and MDA, and rescued the cells from NaAsO2 induced apoptosis and related alteration of mitochondria. These data suggest that the arsenic-induced cell apoptosis occurs though the mitochondrial pathway, and is mostly dependent on generation of ROS rather than GSH depletion in Chang human hepatocytes.",
Arsenic,1023929,"Arsenic burden survey among refuse incinerator workers Abstract: <strong>BACKGROUND: </strong>Incinerator workers are not considered to have arsenic overexposure although they have the risk of overexposure to other heavy metals.<br /><br /><strong>AIM: </strong>To examine the relationship between arsenic burden and risk of occupational exposure in employees working at a municipal refuse incinerator by determining the concentrations of arsenic in the blood and urine.<br /><br /><strong>SETTINGS AND DESIGN: </strong>The workers were divided into three groups based on their probability of contact with combustion-generated residues, namely Group 1: indirect contact, Group 2: direct contact and Group 3: no contact. Healthy age- and sex-matched residents living in the vicinity were enrolled as the control group.<br /><br /><strong>MATERIALS AND METHODS: </strong>Heavy metal concentrations were measured by atomic absorption spectrophotometer. Downstream rivers and drinking water of the residents were examined for environmental arsenic pollution. A questionnaire survey concerning the contact history of arsenic was simultaneously conducted.<br /><br /><strong>STATISTICAL ANALYSIS: </strong>Non-parametric tests, cross-tabulation and multinomial logistic regression.<br /><br /><strong>RESULTS: </strong>This study recruited 122 incinerator workers. The urine and blood arsenic concentrations as well as incidences of overexposure were significantly higher in the workers than in control subjects. The workers who had indirect or no contact with combustion-generated residues had significantly higher blood arsenic level. Arsenic contact history could not explain the difference. Airborne and waterborne arsenic pollution were not detected.<br /><br /><strong>CONCLUSION: </strong>Incinerator workers run the risk of being exposed to arsenic pollution, especially those who have incomplete protection in the workplace even though they only have indirect or no contact with combustion-generated pollutants.",
Arsenic,1028618,"Arsenic induces telomerase expression and maintains telomere length in human cord blood cells Abstract: Inorganic arsenic (iAs) is a human carcinogen, well known as a clastogenic compound. To evaluate the molecular mechanism of arsenite (iAs(III)) toxicity, we investigated the effects on cell growth and apoptosis, telomere length, telomerase expression, as well as the formation of reactive oxygen species (ROS) in male and female human cord blood cells in vitro. Incubation with iAs(III) at the concentration of 0.0001 microM increased telomerase mRNA and protein expression maintained both telomere length and cellular growth, and induced mRNA over-expression of the two oncogenes ras and myc. Our results suggest that female cord blood cells are more sensitive than male ones to iAs(III) induced telomerase stimulation at low concentrations, possibly related to the increased expression of ras and myc oncogenes. On the contrary, at the concentration of 1 microM, iAs(III) decreased telomerase expression and telomere length, and induced apoptosis, necrosis and production of reactive oxygen species. Buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, markedly increased the percentage of apoptotic cells, suggesting that GSH is fundamental for detoxification of iAs(III) in cord blood cells. The reactive oxygen species (ROS) scavenger, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), protected cord blood cells from iAs(III) toxicity, and prevented telomere shortening and telomerase down-modulation. It can be concluded that telomerase expression and telomere length are associated with iAs(III) induced cell death, via production of reactive oxygen species, as well as with iAs(III) induced effects on cell differentiation processes and rate of cell growth.",
Arsenic,2279557,"A SAM-dependent methyltransferase cotranscribed with arsenate reductase alters resistance to peptidyl transferase center-binding antibiotics in Azospirillum brasilense Sp7 Abstract: The genome of Azospirillum brasilense harbors a gene encoding S-adenosylmethionine-dependent methyltransferase, which is located downstream of an arsenate reductase gene. Both genes are cotranscribed and translationally coupled. When they were cloned and expressed individually in an arsenate-sensitive strain of Escherichia coli, arsenate reductase conferred tolerance to arsenate; however, methyltransferase failed to do so. Sequence analysis revealed that methyltransferase was more closely related to a PrmB-type N5-glutamine methyltransferase than to the arsenate detoxifying methyltransferase ArsM. Insertional inactivation of prmB gene in A. brasilense resulted in an increased sensitivity to chloramphenicol and resistance to tiamulin and clindamycin, which are known to bind at the peptidyl transferase center (PTC) in the ribosome. These observations suggested that the inability of prmB:km mutant to methylate L3 protein might alter hydrophobicity in the antibiotic-binding pocket of the PTC, which might affect the binding of chloramphenicol, clindamycin, and tiamulin differentially. This is the first report showing the role of PrmB-type N5-glutamine methyltransferases in conferring resistance to tiamulin and clindamycin in any bacterium.",
Arsenic,1339206,"Heavy metals distribution in muscle, liver, kidney and gill of European catfish (Silurus glanis) from Italian Rivers Abstract: The accumulation of heavy metals in freshwaters has direct consequences to man and ecosystem. Thus, in this study, the concentrations of mercury, cadmium, lead, arsenic and chromium in organs of the predator European catfish (Silurus glanis) were investigated. Samples were collected annually in five sites covering the area of the Po River (North Italy) between 2007 and 2009. Metals were differently distributed in the various organs, the highest concentrations of Hg were found in muscle and liver, Cd in kidney, Pb in gill and liver, as in muscle, and of Cr in gill and liver. Our survey found Hg exceeding the Maximum Levels (MLs) of 0.5ppm in 18% of samples, while Pb and Cd were lower than the MLs set by European regulations in muscle tissues (1881/2006/EC and 629/2008/EC). Hg concentrations were significantly related to sampling stations studied, according to the presence of many industrial activities in the catchment area of Bormida and Tanaro Rivers. The finding that Hg did not fit food fish legislation limits indicated that S. glanis flesh might not be utilised for human consumption. A close monitoring of metals pollution is strongly recommended especially in piscivorous fish, cause their bioaccumulation capacity.",
Arsenic,1346920,POTENTIAL OF MACROPHYTE FOR REMOVING ARSENIC FROM AQUEOUS SOLUTION Abstract: ,
Arsenic,1372646,"Comparison of hydride generation and graphite furnace atomic absorption spectrometry for the determination of arsenic in food Abstract: BIOSIS COPYRIGHT: BIOL ABS. Hydride generation (HG) and graphite furnace atomic absorption spectroscopy for determination of arsenic in various foodstuffs are compared. Two methods of sample pre-treatment, wet ashing and pressurized decomposition in an autoclave, are discussed in detail. It is shown that, for the determination of arsenic in foodstuffs, the HG technique is preferable. The relative standard deviation for arsenic determined by the HG technique does not exceed 15.4% for three parallel weighed samples with an arsenic content of 1.0 mg kg-1.",
Arsenic,1017121,"Analysis of neuroglobin mRNA expression in rat brain due to arsenite-induced oxidative stress Abstract: Arsenic (As) in drinking water is a toxicant causing several health problems including nervous system disturbance. Neuroglobin (Ngb) is a tissue globin in nervous system playing protective role against oxidative stress in many injuries. This study was to investigate how long arsenite exposure (sodium arsenite 7.5 mg/kg/day) could induce oxidative stress in blood and brain of rats and to determine whether Ngb expression in rat brain changed due to oxidative stress. Results showed that superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in serum and brain homogenates and reactive oxygen species (ROS) generation in red blood cells (RBCs) did not change in the rats exposed to arsenite for 8 weeks. In the rats exposed to arsenite for 16 weeks, SOD activity decreased (serum: P &lt; 0.05; brain homogenates: P &lt; 0.01) and MDA level increased (P &lt; 0.01) in serum and brain homogenates; ROS production increased (P &lt; 0.01) in RBC. When oxidative stress occurred, Ngb mRNA expression did not change in whole brain, cerebral cortex, midbrain, and hippocampus; however, Ngb mRNA expression increased significantly (P &lt; 0.05) in cerebellum compared to the control group. This study suggests that arsenite exposure for 16 weeks can lead to oxidative stress of blood and brain of rats. Ngb may play a protective role incerebellum when oxidative stress occurs due to arsenite exposure. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.",
Arsenic,1936168,RETENTION AND PENETRATION OF CCA IN WOOD OF FIRST AND SECOND ROTATION OF Eucalyptus urophylla ST Blake Abstract: ,
Arsenic,2149147,"Draft genome sequence of the arsenate-respiring bacterium Chrysiogenes arsenatis strain DSM 11915 Abstract: Here we present the draft genome sequence of Chrysiogenes arsenatis strain DSM 11915, only the second genome sequence from the phylum Chrysiogenetes. This strictly anaerobic organism was isolated from arsenic-contaminated gold mine wastewater and respires arsenate or nitrate instead of oxygen. The assembly contains 2,824,977 bp in 22 scaffolds.",
Arsenic,1597404,"Heap bioleaching of refractory arsenic gold concentrates Abstract: In this work, we pretreated refractory arsenic gold concentrate, obtained from the Shaanxi Pangjiahe mine located in Feng county, Shaanxi, China, by heap bioleaching with Acidithiobacillus ferrooxidans (A.f.). The purpose of this research was to evaluate the feasibility of heap bioleaching on refractory gold concentrate. The samples with an agglomerate agent were bio-leached within a temperature range of 15-28 ºC for periods of 60 d, 132 d and 306 d, respectively, in leaching column. Then the residues were cyanide leached. The highest gold extraction rate increased from 39.97 %, which is the gold extraction rate from the direct cyanidation process, to 88.66 %. Our results demonstrate that the Au extraction rate was linear with the As extraction rate. The redox potential of Fe3+/Fe2+ is the primary potential in the leaching solution and the T.f. activity varied periodically with inhibition and accommodation. Heap bioleaching can probably be applied on refractory gold concentrate. Further study should be carried out to determine ways to shorten the bioleaching time.",
Arsenic,1342819,"Dietary intake of minerals and trace elements in rice on the Jamaican market Abstract: Twenty-five rice brands, available on the Jamaican market, and a local field trial sample were collected and analyzed for 36 essential, non-essential and toxic elements using four techniques: flame atomic absorption spectrophotometry (F-AAS), inductively coupled plasma optical emission spectrometry (ICP-OES), instrumental neutron activation analysis (INAA), and total reflection X-ray fluorescence (TXRF). The mean values for both white and brown rice respectively for calcium (127 mg/kg; 104 mg/kg), chromium (0.08 mg/kg; 0.157 mg/kg), copper (1.65 mg/kg; 2.96 mg/kg), iron (22.3 mg/kg; 20.1 mg/kg), magnesium (371 mg/kg; 1205 mg/kg), manganese (10.5 mg/kg; 26.5 mg/kg), molybdenum (0.790 mg/kg; 0.770 mg/kg), phosphorus (1203 mg/kg; 3361 mg/kg), potassium (913 mg/kg; 2157 mg/kg), selenium (0.108 mg/kg; 0.131 mg/kg), sodium (6.00 mg/kg; 15.1 mg/kg), sulfur (1131 mg/kg; 1291 mg/kg) and zinc (15.6 mg/kg; 20.2 mg/kg) were used to calculate intake values. The percentage contribution to Provisional Tolerable Weekly Intakes were also estimated for the toxic elements aluminum (6.6–17.9%), arsenic (7.8–10.2%), cadmium (5.1–9.0%) and mercury (3.2–12.0%) with ranges dependent on white or brown rice consumption and gender. It was concluded that, for most essential elements, rice does not significantly contribute to mineral nutrition. The local field trial sample yielded encouraging results in terms of uptake of toxic elements.",
Arsenic,1018601,"Dimethylarsinic acid causes apoptosis in HL-60 cells via interaction with glutathione Abstract: Inducibility of apoptosis in cultured human HL-60 cells by arsenic compounds, such as arsenite, arsenate, methylarsonic acid (MAA), and dimethylarsinic acid (DMAA), was investigated, together with the role of glutathione (GSH) in the induction. Among the arsenic compounds DMAA was the most potent in terms of the ability to cause the morphological changes (formation of nuclear fragmentation and apoptotic bodies) characteristic of apoptosis. Furthermore, fragmentation of internucleosomal DNA was also induced by DMAA. Depletion of cell GSH by L-buthionine-SR-sulfoximine, a selective inhibitor of gamma-glutamylcysteine synthetase, enhanced the cytotoxicity of arsenite, arsenate, and MAA, while such depletion suppressed the cytotoxicity of DMAA. The depletion of GSH also suppressed the morphological changes and the fragmentation of internucleosomal DNA caused by DMAA, both of which are characteristic features of apoptosis. The results suggest that the death of cells caused by DMAA is due to apoptosis and that GSH is involved in the induction of apoptosis by this arsenic compound.",
Arsenic,1022088,"Impact of tubewell access and tubewell depth on childhood diarrhea in Matlab, Bangladesh Abstract: <strong>BACKGROUND: </strong>During the past three decades in Bangladesh, millions of tubewells have been installed to reduce the prevalence of diarrheal disease. This study evaluates the impacts of tubewell access and tubewell depth on childhood diarrhea in rural Bangladesh.<br /><br /><strong>METHODS: </strong>A total of 59,796 cases of diarrhea in children under 5 were recorded in 142 villages of Matlab, Bangladesh during monthly community health surveys between 2000 and 2006. The location and depth of 12,018 tubewells were surveyed in 2002-04 and integrated with diarrhea and other data in a geographic information system. A proxy for tubewell access was developed by calculating the local density of tubewells around households. Logistic regression models were built to examine the relationship between childhood diarrhea, tubewell density and tubewell depth. Wealth, adult female education, flood control, population density and the child's age were considered as potential confounders.<br /><br /><strong>RESULTS: </strong>Baris (patrilineally-related clusters of households) with greater tubewell density were associated with significantly less diarrhea (OR (odds ratio) = 0.87, 95% confidence interval (CI): 0.85-0.89). Tubewell density had a greater influence on childhood diarrhea in areas that were not protected from flooding. Baris using intermediate depth tubewells (140-300 feet) were associated with more childhood diarrhea (OR = 1.24, 95% CI: 1.19-1.29) than those using shallow wells (10-140 feet). Baris using deep wells (300-990 feet) had less diarrheal disease than those using shallow wells, however, the difference was significant only when population density was low (&lt; 1000 person/km(2)) or children were at the age of 13-24 months.<br /><br /><strong>CONCLUSIONS: </strong>Increased access to tubewells is associated with a lower risk of childhood diarrhea. Intermediate- depth wells are associated with more childhood diarrhea compared to shallower or deeper wells. These findings may have implications for on-going efforts to reduce exposure to elevated levels of arsenic contained in groundwater that is pumped in this study area primarily from shallow tubewells.",
Arsenic,1597309,"Influence of the Activity of Allobophora molleri in Microbial Activity and Metal Availability of Arsenic-Polluted Soils Abstract: We investigate the use of Allolobophora molleri as a biomarker of arsenic (As)-polluted soils and study the influence of A. molleri on the metabolic activity and microbial biodiversity of soil polluted with As. Because there are no experimental data available regarding the effect of the pollutant rate of As on A. molleri, we determined the LC50 that was 143.5 mg As kg(-1). Sodium arsenite was added at two rates, equivalent to 143.5 and 71.8 mg As kg(-1) soil, to a soil that was then maintained with and without worms for 120 days. In addition, a nonpolluted soil without and with earthworms was used as the control. The As concentration in the soil was measured after 7 and 120 and the worm weight and As concentration after 120 days of exposure. Soil enzymatic activities and the structure of the soil microbial community, by analysis of phospholipid fatty acids, were determined. At the end of the experiment, the highest earthworm As contents were found in soils polluted with the highest rate of As. Earthworm weights significantly decreased in soil polluted with 143.5 or 71.8 mg As kg(-1), by 49.9 and 29.8 % of initial weight, because the worm consumption rate decreased. These results suggest that A. molleri can be used as a good biomarker of the As toxicity. The As available fraction decreased in polluted soil with worms because the metal was accumulated in worm tissues. However, this assimilation was lower than other worms such as L. rubbellus or L. terrestris. Soil enzymatic activities were decreased in As-polluted soils but were increased significantly by the presence of earthworms. The earthworms modified the soil microbial diversity. In this respect, A. molleri significantly increased (p &lt; 0.05) the bacterial and fungal populations. Soil As pollution decreased microbial biodiversity but to a lesser extent in the presence of A. molleri.",
Arsenic,627335,"Arsenic induces human keratinocyte apoptosis by the FAS/FAS ligand pathway, which correlates with alterations in nuclear factor-?B and activator protein-1 activity Abstract: Epidemiologic studies demonstrated that long-term exposure to arsenic induces arsenical skin cancers, including Bowen’s disease. Immunohistochemically, Bowen’s disease shows proliferating and apoptotic characteristics. The transcription factors nuclear factor-jB (NF-jB) and activator protein-1 (AP-1) functionally regulate cell proliferation, transformation, and apoptosis. To investigate the mechanism of arsenic-induced apoptosis and related alterations in NF-jB and AP-1 activity, we exposed cultured human foreskin keratinocytes to different concentrations of sodium arsenite. At lower concentrations (p1 lM), arsenic induced keratinocyte proliferation and enhanced both",
Arsenic,1031483,"Arsenic induces oxidative stress, sphingolipidosis, depletes proteins and some antioxidants in various regions of rat brain Abstract: <strong>OBJECTIVES: </strong>To seek an interrelationship, if any, between oxidant stress and neurochemical changes in various rat brain regions after arsenic exposure.<br /><br /><strong>MATERIALS AND METHODS: </strong>This study was carried out at the Department of Biochemistry, Al Arab Medical University, Benghazi, Libya. Seventy five male Spraque-Dawley rats were divided into three groups: CONTROL GROUP: Rats were administered 2 ml of normal saline solution/kg body weight (b.wt.) daily for 20 days by intraperitoneal (i.p.) route. ARSENIC-TREATED GROUP: Rats received elemental arsenic (as sodium arsenate) 2.0 mg/kg b.wt. daily for 20 days by i.p. route. RECOVERY GROUP: Rats received 2.0 mg/kg b.wt. elemental arsenic daily for 20 days by i.p. route and were allowed to recover for 20 days. Rats were sacrificed and brains were dissected into cerebral cortex, corpus striatum, cerebellum and brain stem. Tissue homogenized in respective mediums. And were analyzed for lipid classes, oxidative stress, concentration of proteins, glutathione and ascorbic acid by utilizing standard colorimetric procedures.<br /><br /><strong>RESULTS: </strong>Arsenic exposure increased the oxidant stress because lipid peroxidation was enhanced. And decreased the contents of lipid classes, proteins, glutathione and the ascorbic acid in various rat brain regions. However, thins-layer chromatography exhibited regional variations in phospholipids classes.<br /><br /><strong>CONCLUSION: </strong>These results suggested that arsenic-initiated oxidant stress by increasing lipid peroxidation. The losses of lipid classes, ascorbic acid and glutathione may be attributed to peroxidative damage and binding of arsenic with sulfhydryl groups of enzymes. Recovery of animals showed reversibility in most of studied parameters, but gangliosides and cerebrosides over shooted. And speculated &quot;Sphingolipidosis&quot;. It is then likely that repeated exposures of humans to arsenic may result in hampering of cell signalling, apoptosis and mutagenesis.",
Arsenic,2279138,"Preparation and performance of arsenate (V) adsorbents derived from concrete wastes Abstract: Solid adsorbent materials, prepared from waste cement powder and concrete sludge were assessed for removal of arsenic in the form of arsenic (As(V)) from water. All the materials exhibited arsenic removal capacity when added to distilled water containing 10-700mg/L arsenic. The arsenic removal isotherms were expressed by the Langmuir type equations, and the highest removal capacity was observed for the adsorbent prepared from concrete sludge with heat treatment at 105°C, the maximum removal capacity being 175mg-As(V)/g. Based on changes in arsenic and calcium ion concentrations, and solution pH, the removal mechanism for arsenic was considered to involve the precipitation of calcium arsenate, Ca3(AsO4)2. The enhanced removal of arsenic for the adsorbent prepared from concrete sludge with heat treatment was thought to reflect ion exchange by ettringite. The prepared adsorbents, derived from waste cement and concrete using simple procedures, may offer a cost effective approach for arsenic removal and clean-up of contaminated waters, especially in developing countries.",
Arsenic,2149183,"Accumulation of heavy metals in leaf vegetables from agricultural soils and associated potential health risks in the Pearl River Delta, South China Abstract: This study investigated the extent of heavy metal accumulation in leaf vegetables and associated potential health risks in agricultural areas of the Pearl River Delta (PRD), South China. Total concentrations of mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr) and arsenic (As) were determined in 92 pairs of soil and leaf vegetable (flowering Chinese cabbage, lettuce, pakchoi, Chinese cabbage, loose-leaf lettuce, and Chinese leaf mustard) samples collected from seven agricultural areas (cities). The bioconcentration factors (BCF) of heavy metals from soil to vegetables were estimated, and the potential health risks of heavy metal exposure to the PRD residents through consumption of local leaf vegetables were assessed. Results showed that among the six leaf vegetables, pakchoi had the lowest capacity for heavy metal enrichment, whereas among the five heavy metals, Cd had the highest capacity for transferring from soil into vegetables, with BCF values 30-fold those of Hg and 50-fold those of Cr, Pb and As. Sewage irrigation and fertilization were likely the main sources of heavy metals accumulated in leaf vegetables grown in agricultural areas of the PRD region. Different from previous findings, soil pH had no clear effect on metal accumulation in leaf vegetables. Despite a certain degree of metal enrichment from soil to leaf vegetables, the PRD residents were not exposed to significant health risks associated with consumption of local leaf vegetables. Nevertheless, more attention should be paid to children due to their sensitivity to metal pollutants.",
Arsenic,601043,"Angiogenic Potential of 3-Nitro-4-Hydroxy Benzene Arsonic Acid (Roxarsone) Abstract: BACKGROUND: Roxarsone (3-nitro-4-hydroxy benzene arsonic acid) is an arsenic compound widely used in the poultry industry as a feed additive to prevent coccidiosis, stimulate growth, and to improve tissue pigmentation. Little is known about the potential human health effects from roxarsone released into the environment from chicken waste or from residual compound in chicken products. OBJECTIVE: The growth potentiation and enhanced tissue pigmentation suggest that low levels of roxarsone exposure may have an angiogenic potential similar to that of inorganic arsenite (As<sup>III</sup>). The goal of this investigation was to test the hypothesis described above using cultured human aortic and lung microvascular endothelial cells in high-content imaging tube-forming assays and begin developing a molecular level understanding of the process. METHODS: We used a three-dimensional Matrigel assay for probing angiogenesis in cultured human endothelial cells, and a polymerase chain reaction (PCR) array to probe the gene changes as a function of roxarsone or As<sup>III</sup> treatment. In addition, we used Western blot analysis for changes in protein concentration and activation. RESULTS: Roxarsone was found to exhibit a higher angiogenic index than As<sup>III</sup> at lower concentrations. Increased endothelial nitric oxide synthase (eNOS) activity was observed for roxarsone but not for As<sup>III</sup>-induced angiogenesis. However, As<sup>III</sup> caused more rapid and pronounced phosphorylation of eNOS. Quantitative PCR array on select genes revealed that the two compounds have different and often opposite effects on angiogenic gene expression. CONCLUSIONS: The results demonstrate that roxarsone and As<sup>III</sup> promote angiogenic phenotype in human endothelial cells through distinctly different signaling mechanisms. ABSTRACT FROM AUTHOR Copyright of Environmental Health Perspectives is the property of Superintendent of Documents and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,2088422,"Sorption of Oxoanions of As(V), Sb(V) and P(V) and Their Mixtures on Synthetic Goethite Abstract: ",
Arsenic,2278603,"Invasive pneumococcal disease, comorbidities, and polysaccharide vaccine use in children aged 5-15 years in England and Wales Abstract: <strong>BACKGROUND: </strong>In the United Kingdom, the 23-valent pneumococcal polysaccharide vaccine (PPV23) is recommended in addition to routine pneumococcal conjugate vaccination for at-risk children aged ?2 years. This study describes the epidemiology, serotype distribution, clinical characteristics, vaccination status, and reasons for nonvaccination in children aged 5-15 years with invasive pneumococcal disease (IPD).<br /><br /><strong>METHODS: </strong>Public Health England conducts enhanced national surveillance of IPD in England and Wales. In 2012, general practitioners (GPs) were contacted to complete a questionnaire for children aged 5-15 years with laboratory-confirmed IPD diagnosed during 2 epidemiological years, July 2009-June 2011.<br /><br /><strong>RESULTS: </strong>During 2009-2011, 447 IPD episodes occurred in 439 children (incidence, 2.2/100 000), and GPs of 423 of the 439 (96.4%) children completed the questionnaire. Comorbidity was reported in 124 (29.3%); a third each were immunocompromised or had chronic respiratory disease or other comorbidities. Pneumonia was the most common presentation (332/439 [75.6%]), and IPD-related case fatality was 1.8% (8/439). Only 26.6% (33/124) of children with comorbidities had received PPV23, and development of PPV23-type IPD was not associated with prior PPV23 vaccination (adjusted odds ratio [AOR], 1.09; 95% confidence interval [CI], .36-3.32; P = .88), even when analysis was restricted to the extra 11 PPV23 serotypes not contained in the 13-valent pneumococcal conjugate vaccine (AOR, 1.70; 95% CI, .30-9.76; P = .55). GPs of eligible but unvaccinated cases with comorbidities were mostly unaware that the child required PPV23 and/or expected pediatricians to inform them to administer the vaccine.<br /><br /><strong>CONCLUSIONS: </strong>Only a quarter of children with comorbidities who developed IPD had received PPV23 prior to infection. Among PPV23-vaccinated children with comorbidities, however, there was no evidence of protection against PPV23 serotypes.",
Arsenic,1019211,"Oxidative stress in liver of mice exposed to arsenic-contaminated water Abstract: <strong>BACKGROUND: </strong>Oxidative stress has been implicated in the initiation of hepatic damage caused by various agents. Not much data on oxidative stress in liver in chronic arsenic exposure are available in the literature. We therefore studied this aspect in a murine model.<br /><br /><strong>METHODS: </strong>BALB/c mice were given arsenic-contaminated (3.2 mg/L) or arsenic-free (&lt; 0.01 mg/L, control) drinking water ad libitum. Batches of mice were sacrificed after 2 and 4 months, and blood samples and liver tissue were collected. Liver histology was examined and levels of hepatic reduced glutathione (GSH), malondialdehyde, and enzymes of the antioxidant defense system in the liver tissue were determined. Arsenic content in liver tissues obtained at 4 months was estimated.<br /><br /><strong>RESULTS: </strong>Two-month exposure to arsenic caused significant elevation of hepatic GSH (11.4 [0.8] micrograms/mg protein) compared to control mice (9.3 [0.4]; p &lt; 0.01). Levels of enzymes related to GSH homeostasis were also elevated. At 4 months, hepatic GSH was significantly reduced (8.4 [0.5] micrograms/mg protein) when compared to control mice (9.3 [0.4]; p &lt; 0.01). Arsenic content in the liver tissue after 4 months of exposure was significantly higher (0.40 [0.05] microgram/g) as compared to control mice (0.04 [0.04]; p &lt; 0.01).<br /><br /><strong>CONCLUSION: </strong>The results suggest that the antioxidant defense system in the liver of mice is activated after exposure to arsenic for 2 months. However, prolonged exposure to arsenic probably causes overuse failure of this system, which might result in initiation of biochemical injury to the liver.",
Arsenic,2298716,"DNA microarray analysis reveals that antibiotic resistance-gene diversity in human gut microbiota is age related Abstract: The human gut is a reservoir for antibiotic resistance genes. In this report, we used a DNA microarray chip covering 369 resistance types to investigate the relationship between antibiotic resistance-gene diversity and human age. Metagenomic DNA from fecal samples from 124 healthy volunteers of four different age groups (pre-school-aged children (CH), school-aged children (SC), high school students (HSS) and adults (AD)) were hybridized to the microarray chip. The results showed that 80 different gene types were recovered from the gut microbiota of the 124 individuals: 25 from CH, 37 from SC, 58 from HSS and 72 from AD. Further analysis indicated that the antibiotic resistance genes in the CH, SC and AD groups clustered independently, whereas the gene types in the HSS group were more divergent. Our results indicated that antibiotic resistance genes in the human gut microbiota accumulate from childhood to adulthood and become more complex with age.",
Arsenic,1508726,"MiroCam™ capsule for obscure gastrointestinal bleeding: A prospective, single centre experience Abstract: <strong>BACKGROUND: </strong>Capsule endoscopy is an established tool for the evaluation of obscure gastrointestinal bleeding but published literature is mostly limited to PillCam SB (Given Imaging, Israel).<br /><br /><strong>AIMS: </strong>The aims of this study were to determine the findings, the diagnostic yield and the rebleeding rate in a series of patients with overt or occult obscure gastrointestinal bleeding studied with MiroCam(Intromedic, Seoul, Korea) capsule endoscopy.<br /><br /><strong>METHODS: </strong>Data of 118 patients who underwent capsule endoscopy for overt or occult obscure gastrointestinal bleeding were prospectively collected between March 2009 and March 2011.<br /><br /><strong>RESULTS: </strong>Evaluation of the entire small bowel (completion rate) was achieved in 96% of cases. Relevant lesions occurred in 58% of patients. Angiodysplasias was the most common finding. Six patients (9% of the positive findings) had a non-small-bowel lesion detected by capsule. The yield of capsule endoscopy in the overt group was greater than in the occult group but without achieving a significant difference (61% vs. 54%, p&gt;0.05). Rebleeding rate was lower in patients with a negative examination (6%) than in patients with a positive one (17%) (p=0.03). Capsule retention was registered in 3 of 118 patients (2.5%).<br /><br /><strong>CONCLUSIONS: </strong>MiroCam capsule endoscopy is a safe and effective tool for exploring small bowel with a high completion rate.",
Arsenic,656927,"Arsenic exposure in utero exacerbates skin cancer response in adulthood with contemporaneous distortion of tumor stem cell dynamics Abstract: Arsenic is a carcinogen with transplacental activity that can affect human skin stem cell population dynamics in vitro by blocking exit into differentiation pathways. Keratinocyte stem cells (KSC) are probably a key target in skin carcinogenesis. Thus, we tested the effects of fetal arsenic exposure in Tg.AC mice, a strain sensitive to skin carcinogenesis via activation of the v-Ha-ras transgene likely in KSCs. After fetal arsenic treatment, offspring received topical 12-O-tetradecanoyl phorbol-13-acetate (TPA) through adulthood. Arsenic alone had no effect, whereas TPA alone induced papillomas and squamous cell carcinomas (SCC). However, fetal arsenic treatment before TPA increased SCC multiplicity 3-fold more than TPA alone, and these SCCs were much more aggressive (invasive, etc.). Tumor v-Ha-ras levels were 3-fold higher with arsenic plus TPA than TPA alone, and v-Ha-ras was overexpressed early on in arsenic-treated fetal skin. CD34, considered a marker for both KSCs and skin cancer stem cells, and Rac1, a key gene stimulating KSC self-renewal, were greatly increased in tumors produced by arsenic plus TPA exposure versus TPA alone, and both were elevated in arsenic-treated fetal skin. Greatly increased numbers of CD34-positive probable cancer stem cells and marked overexpression of RAC1 protein occurred in tumors induced by arsenic plus TPA compared with TPA alone. Thus, fetal arsenic exposure, although by itself oncogenically inactive in skin, facilitated cancer response in association with distorted skin tumor stem cell signaling and population dynamics, implicating stem cells as a target of arsenic in the fetal basis of skin cancer in adulthood. [Cancer Res 2008;68(20):8278–85]",
Arsenic,1519091,"Remediation of inorganic arsenic in groundwater for safe water supply: A critical assessment of technological solutions Abstract: Arsenic contaminations of groundwater in several parts of the world are the results of natural and/or anthropogenic sources, and have a large impact on human health. Millions of people from different countries rely on groundwater containing As for drinking purposes. This paper reviews removal technologies (oxidation, coagulation flocculation, adsorption, ion exchange and membrane processes) with attention for the drawbacks and limitations of these applied technologies. The technologies suggested and applied for treatment of As rich water have various problems, including the need for further treatment of As containing secondary waste generated from these water treatment processes. More efficient technologies, with a lower tendency to generate waste include the removal of As by membrane distillation or forward osmosis, instead of using pressure driven membrane processes and subsequently reducing soluble As to commercially valuable metallic As are surveyed. An integrated approach of two or more techniques is suggested to be more beneficial than a single process. Advanced technologies such as membrane distillation, forward osmosis as well as some hybrid integrated techniques and their potentials are also discussed in this review. Membrane processes combined with other process (especially iron based technologies) are thought to be most sustainable for the removal of arsenic and further research allowing scale up of these technologies is suggested.",
Arsenic,628459,"Animal models for arsenic carcinogenesis: Inorganic arsenic is a transplacental carcinogen in mice Abstract: Inorganic arsenic is a known human carcinogen causing tumors of the skin, urinary bladder, lung, liver, kidney, and possibly other organs. However, the animal models for inorganic arsenic carcinogenesis have been limited and development has been problematic. Gestation is often a period of high sensitivity to carcinogenesis so we investigated inorganic arsenite as a transplacental carcinogen in mice. Pregnant C3H mice were exposed to sodium arsenite (0, 42.5, and 85 ppm as arsenic) in the drinking water for a brief period during gestation (from gestation day 8 to 18), with no further arsenic exposure or other treatments. The offsprings were monitored up to 90 weeks. Transplacental inorganic arsenic exposure produced a dose-dependent induction of tumors in the liver, adrenal, lung, and ovary in the offsprings after they had reached adulthood. This included hepatocellular carcinoma (HCC), a tumor associated with arsenic exposure in humans. These tumors occurred when mice became adults in the absence of any other treatments and well after arsenic exposure had ended. Genomic analysis of liver tumors and tumor-surrounding tissues revealed several patterns of aberrant gene expression associated with transplacental arsenic carcinogenesis. This animal model demonstrated that inorganic arsenic could act as a ""complete"" transplacental carcinogen in mice. In addition, other important animal models for inorganic arsenic as a skin tumor co-promoter or as a co-carcinogen are discussed. The development of these animal models should advance our understanding of the mechanisms of inorganic arsenic carcinogenesis.",
Arsenic,2278657,"Phytoprotective effect of arbuscular mycorrhizal fungi species against arsenic toxicity in tropical leguminous species Abstract: Arbuscular mycorrhizal fungi (AMF) improve the tolerance of hosting plants to arsenic (As) in contaminated soils. This work assessed the phytoprotective effect of Glomus etunicatum, Acaulospora morrowiae, Gigaspora gigantea, and Acaulospora sp. on four leguminous species (Acacia mangium, Crotalaria juncea, Enterolobium contortisiliquum, and Stizolobium aterrimum) in an As-contaminated soil from a gold mining area. AMF root colonization, biomass production, As and P accumulation, as well as arsenic translocation index (TI) from roots to shoots were measured. The AMF phytoprotective effect was assessed by the P/As ratio and the activity of plant antioxidant enzymes. The AMF colonization ranged from 24 to 28%. In general, all leguminous species had low As TI when inoculated with AMF species. Inoculation of C. juncea with Acaulospora sp. improved significantly As accumulation in roots, and decreased the activity of ascorbate peroxidase (APX) and superoxide dismutase (SOD), highlighting its phytoprotective effect and the potential use of this symbiosis for phytoremediation of As-contaminated soils. However, S. aterrimum has also shown a potential for phytoremediation irrespectively of AMF inoculation. APX was a good indicator of the phytoprotective effect against As contamination in C. juncea and A. mangium. In general P/As ratio in shoots was the best indicator of the phytoprotective effect of all AMF species in all plant species.",
Arsenic,1340043,"A cluster-based randomized controlled trial promoting community participation in arsenic mitigation efforts in Bangladesh Abstract: <strong>UNLABELLED: </strong>ABSTRACT:<br /><br /><strong>OBJECTIVE: </strong>To reduce arsenic (As) exposure, we evaluated the effectiveness of training community members to perform water arsenic (WAs) testing and provide As education compared to sending representatives from outside communities to conduct these tasks.<br /><br /><strong>METHODS: </strong>We conducted a cluster based randomized controlled trial of 20 villages in Singair, Bangladesh. Fifty eligible respondents were randomly selected in each village. In 10 villages, a community member provided As education and WAs testing. In a second set of 10 villages an outside representative performed these tasks.<br /><br /><strong>RESULTS: </strong>Overall, 53% of respondents using As contaminated wells, relative to the Bangladesh As standard of 50??g/L, at baseline switched after receiving the intervention. Further, when there was less than 60% arsenic contaminated wells in a village, the classification used by the Bangladeshi and UNICEF, 74% of study households in the community tester villages, and 72% of households in the outside tester villages reported switching to an As safe drinking water source . Switching was more common in the outside-tester (63%) versus community-tester villages (44%). However, after adjusting for the availability of arsenic safe drinking water sources, well switching did not differ significantly by type of As tester (Odds ratio =0.86[95% confidence interval 0.42-1.77). At follow-up, among those using As contaminated wells who switched to safe wells, average urinary As concentrations significantly decreased.<br /><br /><strong>CONCLUSION: </strong>The overall intervention was effective in reducing As exposure provided there were As-safe drinking water sources available. However, there was not a significant difference observed in the ability of the community and outside testers to encourage study households to use As-safe water sources. The findings of this study suggest that As education and WAs testing programs provided by As testers, irrespective of their residence, could be used as an effective, low cost approach to reduce As exposure in many As-affected areas of Bangladesh.",
Arsenic,1509357,"Lead and arsenic uptake by leafy vegetables grown on contaminated soils: Effects of mineral and organic amendments Abstract: To assess strategies for mitigating Pb and As transfer into leafy vegetables from contaminated garden soils, we conducted greenhouse experiments using two field-contaminated soils amended with materials expected to reduce metal phytoavailability. Lettuce and mustard greens grown on these soils were analyzed by ICP-MS, showing that some Pb and As transfer into the vegetables occurred from both soils tested, but plant Pb concentrations were highly variable among treatment replicates. Soil-to-plant transfer was more efficient for As than for Pb. Contamination of the leaves by soil particles probably accounted for most of the vegetable Pb, since plant Pb concentrations were correlated to plant tissue concentrations of the immobile soil elements Al and Fe. This correlation was not observed for vegetable As concentrations, evidence that most of the soil-to-plant transfer for this toxic metal occurred by root uptake and translocation into the above-ground tissues. A follow-up greenhouse experiment with lettuce on one of the two contaminated soils revealed a lower and less variable foliar Pb concentration than observed in the first experiment, with evidence of less soil particle contamination of the crop. This reduced transfer of Pb to the crop appeared to be a physical effect attributable to the greater biomass causing reduced overall exposure of the above-ground tissues to the soil surface. Attempts to reduce soil Pb and As solubility and plant uptake by amendment at practical rates with stabilizing materials, including composts, peat, Ca phosphate, gypsum, and Fe oxide, were generally unsuccessful. Only Fe oxide reduced soluble As in the soil, but this effect did not persist. Phosphate amendment rapidly increased soil As solubility but had no measurable effect on either soil Pb solubility or concentrations of Pb or As in the leafy vegetables. The ineffectiveness of these amendments in reducing Pb transfer into leafy vegetables is attributed in this study to the low initial Pb solubility of the studied soils and the fact that the primary mechanism of Pb transfer is physical contamination.",
Arsenic,628330,"Folate deficiency enhances arsenic effects on expression of genes involved in epidermal differentiation in transgenic K6/ODC mouse skin Abstract: Chronic arsenic exposure in humans is associated with cancers of the skin, lung, bladder and other tissues. There is evidence that folate deficiency may increase susceptibility to arsenic effects, including skin lesions. K6/ODC mice develop skin tumors when exposed to 10 ppm sodium arsenite for 5 months. In the current study, K6/ODC mice maintained on either a folate deficient or folate sufficient diet were exposed to 0, 1, or 10 ppm sodium arsenite in the drinking water for 30 days. Total RNA was isolated from skin samples and gene expression analyzed using Affymetrix Mouse 430 2.0 GeneChips. Data from 24 samples, with 4 mice in each of the 6 treatment groups, were RMA normalized and analyzed by two-way ANOVA using GeneSpring™. Top gene ontology (GO) categories for genes responding significantly to both arsenic treatment and folate deficiency include nucleotide metabolism and cell organization and biogenesis. For many of these genes, folate deficiency magnifies the response to arsenic treatment. In particular, expression of markers of epidermal differentiation, e.g., loricrin, small proline rich proteins and involucrin, was significantly reduced by arsenic in the folate sufficient animals, and reduced further or at a lower arsenic dose in the folate deficient animals. In addition, expression of a number of epidermal cell growth/proliferation genes and cellular movement genes was altered. These results indicate that arsenic disrupts the normal balance of cell proliferation and differentiation, and that folate deficiency exacerbates these effects, consistent with the view that folate deficiency is a nutritional susceptibility factor for arsenic-induced skin tumorigenesis.",
Arsenic,1034742,Difficulties in the determination of arsenic by atomic absorption spectrometry Abstract: ,
Arsenic,157923,"Carcinogens induce reversion of the mouse pink-eyed unstable mutation Abstract: Deletions and other genome rearrangements are associated with carcinogenesis and inheritable diseases. The pink-eyed unstable (pun) mutation in the mouse is caused by duplication of a 70-kb internal fragment of the p gene. Spontaneous reversion events in homozygous pun/pun mice occur through deletion of a duplicated sequence. Reversion events in premelanocytes in the mouse embryo detected as black spots on the gray fur of the offspring were inducible by the carcinogen x-rays, ethyl methanesulfonate, methyl methanesulfonate, ethyl nitrosourea, benzo[a]pyrene, trichloroethylene, benzene, and sodium arsenate. The latter three carcinogens are not detectable with several in vitro or in vivo mutagenesis assays. We studied the molecular mechanism of the carcinogen-induced reversion events by cDNA analysis using reverse transcriptase-PCR method and identified the induced reversion events as deletions. DNA deletion assays may be sensitive indicators for carcinogen exposure.",
Arsenic,2337069,"Sequestration of arsenate from aqueous solution using 2-line ferrihydrite: equilibria, kinetics, and X-ray absorption spectroscopic analysis Abstract: Arsenic(V), as the arsenate (AsO4 (3-)) ion and its conjugate acids, has a strong affinity on Fe, Mn, and Al (oxyhydr)oxides and clay minerals. Removal of arsenate from aqueous solution by poorly crystalline ferrihydrite (hydrous ferric oxide) via a combination of macroscopic (equilibria and kinetics of sorption) and X-ray absorption spectroscopic studies was investigated. The removal of arsenate significantly decreased with increasing pH and sorption maxima of approximately 1.994 mmol/g (0.192 mol(As)/mol(Fe)) were achieved at pH 2.0. The Langmuir isotherm is most appropriate for arsenate sorption over the wide range of pH, indicating that arsenate sorption preferentially takes place at relatively homogenous and monolayer sites rather than heterogeneous and multilayer surfaces. The kinetic study demonstrated that arsenate sorption onto 2-line ferrihydrite is considerably fast, and sorption equilibrium was achieved within the reaction time of 2 h. X-ray absorption near-edge structure spectroscopy indicates no change in oxidation state of arsenate following interaction with the ferrihydrite surfaces. Extended X-ray absorption fine structure spectroscopy supports the efficient removal of arsenate by the 2-line ferrihydrite through the formation of highly stable inner-sphere surface complexes, such as bidentate binuclear corner-sharing (C-2) and bidentate mononuclear edge-sharing (E-2) complexes.",
Arsenic,1018492,"Estimation of dietary intake of arsenic in the general population of the Republic of Croatia Abstract: Total amounts of arsenic in foods sold in Croatia were determined over a 5-year period (1988-1993). Highest mean levels were recorded in the following food groups: fish (498 micrograms/kg), fishery products (270 micrograms/kg) and cheese and dairy products (39 micrograms/kg); lowest levels were contained in fruit, chocolate and fruit products (0.2, 0.2 and 0.3 microgram/kg, respectively). Mean weekly dietary arsenic intake estimated on the basis of the level of arsenic and consumption of the studied foodstuffs is 81.9 micrograms/individual. The PTWI level achieved by the general population of Croatia is 7.8%.",
Arsenic,2088507,"Trivalent arsenic species induce changes in expression and levels of proinflammatory cytokines in intestinal epithelial cells Abstract: Chronic arsenic (As) toxicity in humans has been documented in many countries where exposure mostly occurs through drinking water. The As immunotoxic effects have been demonstrated in animal models as well as in humans. The studies of the immunotoxicity of As have centered on organs related to immune response or target organs, with few data being available at intestinal level. The present study has evaluated the changes in the expression and release of cytokines in Caco-2 cells, widely used as an intestinal epithelial model. Differentiated cells were exposed to 1 ?M of As(III), 0.1 ?M of monomethylarsonous acid [MMA(III)] and 1 ?M of dimethylarsinous acid [DMA(III)] during 2, 4, 6 and 24 h. Additionally, the effect of As coexposure with lipopolysaccharide (LPS, 10 ng/mL) has been evaluated. The results show trivalent species to induce increases in the expression and release of the proinflammatory cytokines tumor necrosis factor alpha (TNF?), IL6, IL8, IL1? and IL1? - the magnitude and time of response being different for each As species. The response of greatest magnitude corresponds to DMA(III), followed by As(III), while MMA(III) generates a limited response. Furthermore, the presence of LPS in the co-exposed cells could affect the expression and secretion of cytokines compared with individual exposure to arsenicals, especially for As(III)/LPS and DMA(III)/LPS.",
Arsenic,1252669,"Arsenic uptake, cytotoxicity and detoxification studied in mammalian cells in culture Abstract: The cytotoxicity of trivalent and pentavalent inorganic arsenic salts was determined in mouse fibroblasts in vitro. Concentrations of As (III) in the microM range led to a reduction of proliferation and viability with a concomitant increase in LDH release and stimulation of lactic acid production. Similar effects were noted with approximately 10-fold greater molar concentrations of As(V). Cells pretreated with a low As(III) concentration are less sensitive to toxic doses of As(III) or As(V). Uptake of As(III) by the fibroblasts is greater than that of As(V). Both forms of inorganic arsenic are converted intracellularly to monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are then released into the culture medium. In As-pretreated cells, which are more resistant to As toxicity, biotransformation of inorganic arsenic to MMA and DMA is increased.",
Arsenic,1509333,On the way to artificial photosynthesis: Simple materials and system designs for photoelectrodes Abstract: For commercial viability new technologies for the sustainable generation of energy should be simple and efficient. Photoelectrodes made of boron arsenide are the latest advance: they can be synthesized easily directly from the elements and convert sunlight into electric current.,
Arsenic,1018432,Cancer risk in an arsenic-contaminated area of Chile Abstract: ,
Arsenic,2279030,"Axon guidance factor SLIT2 inhibits neural invasion and metastasis in pancreatic cancer Abstract: Pancreatic ductal adenocarcinoma (PDAC) metastasizes by neural, vascular, and local invasion routes, which limit patient survival. In nerves and vessels, SLIT2 and its ROBO receptors constitute repellent guidance cues that also direct epithelial branching. Thus, the SLIT2-ROBO system may represent a key pinch point to regulate PDAC spread. In this study, we examined the hypothesis that escaping from repellent SLIT2-ROBO signaling is essential to enable PDAC cells to appropriate their local stromal infrastructure for dissemination. Through immunohistochemical analysis, we detected SLIT2 receptors ROBO1 and ROBO4 on epithelia, nerves, and vessels in healthy pancreas and PDAC specimens, respectively. SLIT2 mRNA expression was reduced in PDAC compared with nontransformed pancreatic tissues and cell lines, suggesting a reduction in SLIT2-ROBO pathway activity in PDAC. In support of this interpretation, restoring the SLIT2 expression in SLIT2-deficient PDAC cells inhibited their bidirectional chemoattraction with neural cells, and more specifically, impaired unidirectional PDAC cell navigation along outgrowing neurites in models of neural invasion. Restoring autocrine/paracrine SLIT2 signaling was also sufficient to inhibit the directed motility of PDAC cells, but not their random movement. Conversely, RNA interference-mediated silencing of ROBO1 stimulated the motility of SLIT2-competent PDAC cells. Furthermore, culture supernatants from SLIT2-competent PDAC cells impaired migration of endothelial cells (human umbilical vein endothelial cells), whereas an N-terminal SLIT2 cleavage fragment stimulated such migration. In vivo investigations of pancreatic tumors with restored SLIT2 expression demonstrated reduced invasion, metastasis, and vascularization, with opposing effects produced by ROBO1 silencing in tumor cells or sequestration of endogenous SLIT2. Analysis of clinical specimens of PDAC showed that those with low SLIT2 mRNA expression exhibited a higher incidence and a higher fraction of tumor-infiltrated lymph nodes. Taken together, our findings argue that disrupting SLIT2-ROBO signaling in PDAC may enhance metastasis and predispose PDAC cells to neural invasion.",
Arsenic,1353491,"Characteristic of thymus in newborn mice after chronic exposure of their mothers to sodium arsenite Abstract: Thymus morphology from 26 newbon CBA-mice (11 control and 15 experimental animals), whose mothers had been treated by oral administration of 10 mg/kg body weight dose of sodium arsenite for 15 days before and within 15 days of the gestation period, has been studied. The thymus was studied by histological, morphometrical and electronmicroscopical methods. It was found that a total dose of sodium arsenite equal to 300 mg/kg body weight is ""critical"" for pregnant mice as it results in blood-placenta barrier permeability damage and is accompanied with arsenic accumulation in the body of newborns. Development of marked accidental thymus involution in the newborn mice of the experimental group was noted and it was accompanied by high rate of lymphocyte death due to apoptosis.",
Arsenic,2345677,"Stress induced start codon fidelity regulates arsenite inducible regulatory particle associated protein (AIRAP) translation Abstract: Initial steps in protein synthesis are highly regulated processes as they define the reading frame of the translation machinery. Eukaryotic translation initiation is a process facilitated by numerous factors (eIFs), aimed to form a scanning mechanism towards the initiation codon. Translation initiation of the main open reading frame (ORF) in an mRNA transcript has been reported to be regulated by upstream open reading frames (uORFs) in a manner of re-initiation. This mode of regulation is governed by the phosphorylation status of eIF2 ? and controlled by cellular stresses. Another mode of translational initiation regulation is leaky scanning and this regulatory process has not been extensively studied. We have identified arsenite inducible regulatory article associated protein (AIRAP) transcript to be translationally induced during arsenite stress conditions. AIRAP transcript contains a single uORF in a poor-kozak context. AIRAP translation induction is governed by means of leaky scanning and not re-initiation. This induction of AIRAP is solely dependent on eIF1 and the uORF kozak context. We show that eIF1 is phosphorylated under specific conditions that induce protein misfolding and have biochemically characterized this site of phosphorylation. Our data indicate that leaky scanning like re-initiation is responsive to stress conditions and that leaky scanning can induce ORF translation by bypassing poor kozak context of a single uORF transcript.",
Arsenic,627322,"Comutagenesis of sodium arsenite with ultraviolet radiation in Chinese hamster V79 cells Abstract: Solar ultraviolet radiation has been associated with the induction of skin cancer. Recent studies have indicated that near-ultraviolet, especially UVB, is mutagenic. Exposure to trivalent inorganic arsenic compounds has also been associated with increased skin cancer prevalence. Trivalent arsenic compounds are not mutagenic per se, but are comutagenic with a number of cancer agents. Here, we test the hypothesis that arsenite enhances skin cancer via its comutagenic action with solar ultraviolet radiation. Irradiation of Chinese hamster V79 cells with UVA (360 nm), UVB (310 nm) and UVC (254 nm) caused a fluence-dependent increase in mutations at the hprt locus. On an energy basis, UVC was the most mutagenic and UVA the least. However, when expressed as a function of toxicity, UVB was more mutagenic than UVC. Nontoxic concentrations of arsenite increased the toxicity of UVA, UVB and UVC. Arsenite acted as a comutagen at the three wavelengths; however, higher concentrations of arsenite were required to produce a significant (P less than 0.05) comutagenic response with UVB. The increased mutagenicity of UVB and UVA by arsenite may play a role in arsenite-related skin cancers.",
Arsenic,1021777,"Concentration-dependent cellular responses of arsenic in keratinocytes Abstract: Arsenic (As) is considered as a human carcinogen or tumor-promoting agent. Epidemiological evidences indicated that cancer incidences of residents in arseniasis areas were significantly higher in multiple organs, including urinary bladder, lungs, and especially the skin, than those living in non-arseniasis areas. In the context of skin cancers, keratinocytes are believed to be the main target cells in As carcinogenesis. Therefore, we discuss the significance of keratinocyte-specific effects of As on skin carcinogenesis. As is known to be cytotoxic because of its chemical reactions with the thiol group of proteins and its ability to generate free radicals during cellular metabolism. However, at relatively low concentrations, As shows stimulatory effects, such as cell activation and proliferation. Because long-term As exposure is associated with skin carcinogenesis, we reviewed the mechanisms of As-induced keratinocyte dysfunctions by means of time- and concentration-dependent cellular responses. The mechanisms and interactions underlying As-induced keratinocyte dysfunctions not only provide a model of As in skin carcinogenesis process but also help in understanding the regulation of As carcinogenesis in other internal organs.",
Arsenic,1519138,"Identification of potential soil adsorbent for the removal of hazardous metals from aqueous phase Abstract: The present study attempted to identify the efficient hazardous metal-removing sorbent from specific types of soil, upper and middle layer shirasu, shell fossil, tuff, akadama and kanuma soils of Japan by physico-chemical and metal (arsenic, cadmium and lead) removal characterizations. The physico-chemical characteristics of soil were evaluated using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy techniques, whereas metal removal properties of soil were characterized by analyzing removal capacity and sorption kinetics of potential metal-removing soils. The chemical characteristics revealed that all soils are prevalently constituted of silicon dioxide (21.83–78.58 %), aluminum oxide (4.13–38 %) and ferrous oxide (0.835–7.7 %), whereas calcium oxide showed the highest percentage (65.36 %) followed by silicon dioxide (21.83 %) in tuff soil. The results demonstrated that arsenic removal efficiency was higher in elevated aluminum oxide-containing akadama (0.00452 mg/L/g/h) and kanuma (0.00225 mg/L/g/h) soils, whereas cadmium (0.00634 mg/L/g/h) and lead (0.00693 mg/L/g/h) removal efficiencies were maximum in elevated calcium oxide-containing tuff soil. Physico-chemical sorption and ion exchange processes are the metal removal mechanisms. The critical appraisal of three metal removal data also clearly revealed cadmium > lead > arsenic order of removal efficiency in different soils, except in tuff and akadama soils followed by lead > cadmium > arsenic. It clearly signified that each type of soil had a specific metal adsorption affinity which was regulated by the specific chemical composition. It may be concluded that akadama would be potential arsenic-removing and tuff would be efficient cadmium and lead-removing soil sorbents.",
Arsenic,2343522,"As, Cd, Hg and Pb in four edible shellfish species from breeding and harvesting areas along the eastern Adriatic Coast, Croatia Abstract: Four species of shellfish (Mytilus galloprovincialis, Ostrea edulis, Chlamis varia and Venus verrucosa) were collected during the autumn 2011 and spring 2012 along the eastern Adriatic coast from six shellfish harvesting areas (all species) and 13 breeding sampling areas (mussels) to assess As, Cd, Hg and Pb levels and the human risks of shellfish consumption. The mean metal concentrations (wet weight) in the examined species ranged from 1.420 to 9.575mg/kg for As, 0.034 to 1.270 for Cd, 0.005 to 0.680 for Hg and 0.140 to 2.072 for Pb. Examination of the spatial distribution of As, Cd, Hg and Pb revealed statistically significant differences among the studied areas. Since the concentrations were below the maximum prescribed by the laws of the EU and Croatia (the concentrations slightly exceeded the upper limits for three samples; Pb, Cd and Hg) and the hazard index, (HI) for Cd, Hg and Pb were below 1 and the target cancer risk (TR) for As was lower than 1×10(-6), there is no human health risk of consumption of shellfish from Croatian waters.",
Arsenic,1015803,"Effect of seepage conditions on chemical attenuation of arsenic by soils across an abandoned mine site Abstract: The effect of seepage velocity on the As leaching/adsorption by soils collected from abandoned mine sites was evaluated under batch equilibrium and different seepage settings. The breakthrough curves (BTCs) of As leaching from the mine soil column initially displayed the peak export and gradually leveled off over the leaching experiment. A similar As peak was observed after a flow interruption period. Adsorption by downgradient soils was clearly nonlinear, as Freundlich N was &lt;1. In the BTCs of the layered columns, where downgradient soils were overloaded above the mine soil, the extended lag period of As appearance and lower steady-state As concentration observed for slow seepage velocity supported the idea of kinetically limited As attenuation driven by soil adsorption. The perturbation of As concentration was insignificant when the intra-column As concentration gradient was higher. The As concentration drop and time to recovery were greater for less adsorptive soil and fast seepage velocity. Desorption of As from soils retrieved from both batch adsorption and column experiment demonstrate hysteric behavior. The results of this work demonstrated that the risk of As leaching from an abandoned mine site can be greatly attenuated by intermediate downgradient soils via chemical adsorption, which tends to be kinetically limited and energetically hysteric (i.e., non-identical energy pathway).",
Arsenic,1356946,"Sex differences in response to arsenic and advanced maternal age in a C57BL/6J splotch heterozygote cross Abstract: Embryonic susceptibility to teratogens depends on a host of gene-environment interactions. This murine study examines the in utero interactions of the splotch (Sp) mutation in Pax3, embryonic sex, and exposure to arsenic or advanced maternal age. Previous studies in mice have shown an altered sex ratio resulting from maternally-induced diabetes and administration of arsenite. Splotch heterozygous C57BL/6J mice were crossed to produce offspring of three genotypes (+/+, Sp/+, Sp/Sp) that were exposed to either advanced maternal age (dams older than 12 months), or a maternal injection of 10 mg/kg sodium arsenite on gestational day (g.d.) 8.0. Embryos were extracted on either g.d. 10 or 12 (before the Sp/Sp embryos die) and genotyped for Pax3 and sex. Embryos were phenotyped for spina bifida and exencephaly. Arsenite treatment and advanced maternal age resulted in elevated male/female sex ratios for wildtype (2.3) and heterozygous embryos (1.7 for arsenite-treated and 1.9 for advanced-maternal-age). The sex ratio was not significantly different from 1.0 for splotch homozygotes or for the three genotypes from control litters. Therefore, the mutation in the Pax3 gene appears to protect the embryos from a differential sex-based response. Additional embryos have been collected from 23 arsenite-treated Sp/+ x Sp/+ litters. Further experiments will examine if other teratogens induce the same perturbation of the sex ratio, and whether the ratio changes with gestational age. To date, genetic (Pax3 mutation) and environmental (arsenite exposure and advanced maternal age) factors contributed to the determination of murine sex ratios, with female embryos more susceptible to loss.",
Arsenic,2337173,"Geophagy practices and the content of chemical elements in the soil eaten by pregnant women in artisanal and small scale gold mining communities in Tanzania Abstract: <strong>BACKGROUND: </strong>Geophagy, a form of pica, is the deliberate consumption of soil and is relatively common across Sub-Saharan Africa. In Tanzania, pregnant women commonly eat soil sticks sold in the market (pemba), soil from walls of houses, termite mounds, and ground soil (kichuguu). The present study examined geophagy practices of pregnant women in a gold mining area of Geita District in northwestern Tanzania, and also examined the potential for exposure to chemical elements by testing soil samples.<br /><br /><strong>METHOD: </strong>We conducted a cross sectional study using a convenience sample of 340 pregnant women, ranging in age from 15-49 years, who attended six government antenatal clinics in the Geita District, Tanzania. Structured interviews were conducted in June-August, 2012, to understand geophagy practices. In addition, soil samples taken from sources identified by pregnant women practicing geophagy were analysed for mineral element content.<br /><br /><strong>RESULTS: </strong>Geophagy was reported by 155 (45.6%) pregnant women with 85 (54.8%) initiating the practice in the first trimester. A total of 101 (65%) pregnant women reported eating soil 2 to 3 times per day while 20 (13%) ate soil more than 3 times per day. Of 155 pregnant women 107 (69%) bought pemba from local shops, while 48 (31%) consumed ground soil kichuguu. The estimated mean quantity of soil consumed from pemba was 62.5 grams/day. Arsenic, chromium, copper, iron, manganese, nickel and zinc levels were found in both pemba and kichuguu samples. Cadmium and mercury were found only in the kichuguu samples. Based on daily intake estimates, arsenic, copper and manganese for kichuguu and copper and manganese for pemba samples exceed the oral Minimum Risk Levels designated by the U.S. Agency for Toxic Substance and Disease Registry.<br /><br /><strong>CONCLUSION: </strong>Almost 50% of participants practiced geophagy in Geita District consistent with other reports from Africa. Both pemba and kichuguu contained chemical elements at varying concentration, mostly above MRLs. As such, pregnant women who eat soil in Geita District are exposed to potentially high levels of chemical elements, depending upon frequency of consumption, daily amount consumed and the source location of soil eaten.",
Arsenic,2149362,"Procedia Environmental Sciences Multifractal analysis to characterize urban surface dust volume-size distribution Abstract: The amount of ubiquitous urban environment surface dust with high contaminants is directly correlated with the degree of harm to the human body. This paper discusses the surface dust grain-size distribution characteristics by utilizing the multifractal model. The results indicate that urban surface dust particle distribution is a scattered distribution. Renyi-dimension spectra curves of dust are either nearly sigma shaped (q &gt;= 0), or they follow a quasi-linear variation (q &gt; 0). The Renyi dimensions (D(q)) and pH were found to have significance correlation. No relationship was found between D(q) and Arsenic (As). When q &gt; 0, organic matter (OM) and Mercury (Hg) are positively correlated with Renyi dimensions. However, OM and Hg are not correlated with D(q) when q &gt;= 0. The use of this multifractal model could be considered a way to express the contaminant level in dust. It may be taken into consideration in environment management strategies. (C) 2011 Published by Elsevier B. V. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University.",
Arsenic,1339081,"Perinatal exposure to 50 ppb sodium arsenate induces hypothalamic-pituitary-adrenal axis dysregulation in male C57BL/6 mice Abstract: Over the past two decades, key advancements have been made in understanding the complex pathology that occurs following not only high levels of arsenic exposure (&gt;1 ppm) but also levels previously considered to be low (&lt;100 ppb). Past studies have characterized the deleterious effects of arsenic on the various functions of cardiovascular, pulmonary, immunological, respiratory, endocrine and neurological systems. Other research has demonstrated an elevated risk of a multitude of cancers and increased rates of psychopathology, even at very low levels of arsenic exposure. The hypothalamic-pituitary-adrenal (HPA) axis represents a multisite integration center that regulates a wide scope of biological and physiological processes: breakdown within this system can generate an array of far-reaching effects, making it an intriguing candidate for arsenic-mediated damage. Using a mouse model, we examined the effects of perinatal exposure to 50 ppb sodium arsenate on the functioning of the HPA axis through the assessment of corticotrophin-releasing factor (CRF), proopiomelanocortin (Pomc) mRNA, adrenocorticotrophin hormone (ACTH), corticosterone (CORT), 11?-hydroxysteroid dehydrogenase Type 1 (11?-HSD 1), and glucocorticoid receptor (GR) protein and mRNA. Compared to controls, we observed that the perinatal arsenic-exposed offspring exhibit an increase in hypothalamic CRF, altered CORT secretion both at baseline and in response to a stressor, decreased hippocampal 11?-HSD 1 and altered subcellular GR distribution in the hypothalamus. These data indicate significant HPA axis impairment at post-natal day 35 resulting from perinatal exposure to 50 ppb sodium arsenate. Our findings suggest that the dysregulation of this critical regulatory axis could underlie important molecular and cognitive pathology observed following exposure to arsenic.",
Arsenic,1337699,"Remodulation of central carbon metabolic pathway in response to arsenite exposure in Rhodococcus sp. strain NAU-1 Abstract: Arsenite-tolerant bacteria were isolated from an organic farm of Navsari Agricultural University (NAU), Gujarat, India (Latitude: 20°55'39.04?N; Longitude: 72°54'6.34?E). One of the isolates, NAU-1 (aerobic, Gram-positive, non-motile, coccobacilli), was hyper-tolerant to arsenite (As(III) , 23?mM) and arsenate (As(V) , 180?mM). 16S rRNA gene of NAU-1 was 99% similar to the 16S rRNA genes of Rhodococcus (Accession No. HQ659188). Assays confirmed the presence of membrane bound arsenite oxidase and cytoplasmic arsenate reductase in NAU-1. Genes for arsenite transporters (arsB and ACR3(1)) and arsenite oxidase gene (aoxB) were confirmed by PCR. Arsenite oxidation and arsenite efflux genes help the bacteria to tolerate arsenite. Specific activities of antioxidant enzymes (catalase, ascorbate peroxidase, superoxide dismutase and glutathione S-transferase) increased in dose-dependent manner with arsenite, whereas glutathione reductase activity decreased with increase in As(III) concentration. Metabolic studies revealed that Rhodococcus NAU-1 produces excess of gluconic and succinic acids, and also activities of glucose dehydrogenase, phosphoenol pyruvate carboxylase and isocitrate lyase were increased, to cope with the inhibited activities of glucose-6-phosphate dehydrogenase, pyruvate dehydrogenase and ?-ketoglutarate dehydrogenase enzymes respectively, in the presence of As(III) . Enzyme assays revealed the increase in direct oxidative and glyoxylate pathway in Rhodococcus NAU-1 in the presence of As(III) .",
Arsenic,1016783,"Ecological risk assessment of persistent toxic substances for the clam Tapes philipinarum in the Lagoon of Venice, Italy Abstract: Because of contamination of sediments of the Lagoon of Venice, Italy, by inorganic pollutants (e.g., arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc) and organic pollutants (e.g., polychlorobiphenyls), as well as the ecological and economical relevance of the edible clam Tapes philipinarum, an ecological risk assessment was undertaken to ascertain the extent of bioaccumulation that would pose a significant risk. Risk was estimated by means of toxic units and hazard quotient approaches, by comparing the exposure concentration with the effect concentration. Clam exposure was estimated by applying previous results based on bioaccumulation spatial regression models. In addition, a comparison was made between sum of dioxin-like polychlorinated biphenyl (PCB) congeners and total PCB bioaccumulation provided by spatial regression models and by a partitioning model. The effect concentrations were calculated as tissue screening concentrations, as the product of pollutant sediment quality criteria and the bioaccumulation factor. Finally, the cumulative risk posed by selected inorganic pollutants and total PCBs was estimated and a map of risk was drawn. The resulting chemicals of potential ecological concern were mercury, cadmium, arsenic, and nickel, as well as, to a lesser extent, total PCBs.",
Arsenic,1519061,"Advantages of low pH and limited oxygenation in arsenite removal from water by zero-valent iron Abstract: The removal of toxic arsenic species from contaminated waters by zero-valent iron (ZVI) has drawn considerable attention in recent years. In this approach, arsenic ions are mainly removed by adsorption to the iron corrosion products. Reduction to zero-valent arsenic on the ZVI surface is possible in the absence of competing oxidants and can reduce arsenic mobility and sludge formation. However, associated removal rates are relatively low. In the current study, simultaneous high reduction and removal rates of arsenite (H3AsO3), the more toxic and mobile environmentally occurring arsenic species, was demonstrated by reacting it with ZVI under limited aeration and relatively low pH. 90% of the removed arsenic was attached to the ZVI particles and 60% of which was in the elemental state. Under the same non-acidic conditions, only 40-60% of the removed arsenic was attached to the ZVI with no change in arsenic oxidation state. Under anaerobic conditions, reduction occurred but total arsenic removal rate was significantly lower and ZVI demand was higher. The effective arsenite removal under acidic oxygen-limited conditions was explained by formation of Fe(II)-solid intermediate on the ZVI surface that provided high surface area and reducing power.",
Arsenic,1379236,"Rapid analysis of Lewisite metabolites in urine by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry Abstract: A high-throughput method has been developed for determining Lewisite [dichloro(2-chlorovinyl)arsine] exposure by measuring the urine metabolite 2-chlorovinylarsonous acid (CVAA) and the oxidized metabolite 2-chlorovinylarsonic acid (CVAOA). The rapid sample preparation included a simple dilution of 400 microL of urine with 40 microL of water and 1 mL of buffer containing an internal standard and brief centrifugation prior to analysis by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (ICP-MS). CVAOA and CVAA were eluted isocratically with retention factors of approximately 3.0 and 4.2, respectively, from a reversed-phase polar embedded column with a cycle time of 5 min per sample. The dynamic reaction cell, typically used to remove polyatomic isobaric interferences, was not required for ICP-MS analysis because of the resolution of chloride from arsenical peaks of interest. This method was used to detect CVAA and CVAOA in the urine of a rat administered Lewisite up to 24 h after exposure. The method demonstrated linearity over at least three orders of magnitude and had a method detection limit of 1.3 microg/L as CVAA (1.4 microg/L CVAOA). The relative standard deviations for quality control samples ranged from 3 to 6%. The method was sensitive and selective with no false positives in 100 different urine samples collected from individuals with no known exposure to Lewisite. Ninety-six samples could be analyzed in an 8-h day.",
Arsenic,2347687,"Selenium ameliorates arsenic induced oxidative stress through modulation of antioxidant enzymes and thiols in rice (Oryza sativa L.) Abstract: Arsenic (As) contamination of rice is a major problem for South-East Asia. In the present study, the effect of selenium (Se) on rice (Oryza sativa L.) plants exposed to As was studied in hydroponic culture. Arsenic accumulation, plant growth, thiolic ligands and antioxidative enzyme activities were assayed after single (As and Se) and simultaneous supplementations (As + Se). The results indicated that the presence of Se (25 µM) decreased As accumulation by threefold in roots and twofold in shoots as compared to single As (25 µM) exposed plants. Arsenic induced oxidative stress in roots and shoots was significantly ameliorated by Se supplementation. The observed positive response was found associated with the increased activities of ascorbate peroxidase (APX; EC 1.11.1.11), catalase (CAT; EC 1.11.1.6) and glutathione peroxidase (GPx; EC 1.11.1.9) and induced levels of non-protein thiols (NPTs), glutathione (GSH) and phytochelatins (PCs) in As + Se exposed plants as compared to single As treatment. Selenium supplementation modulated the thiol metabolism enzymes viz., ?-glutamylcysteine synthetase (?-ECS; EC 6.3.2.2), glutathione-S-transferase (GST; EC 2.5.1.18) and phytochelatin synthase (PCS; EC 2.3.2.15). Gene expression analysis of several metalloid responsive genes (LOX, SOD and MATE) showed upregulation during As stress, however, significant downregulation during As + Se exposure as compared to single As treatment. Gene expressions of enzymes of antioxidant and GSH and PC biosynthetic systems, such as APX, CAT, GPx, ?-ECS and PCS were found to be significantly positively correlated with their enzyme activities. The findings suggested that Se supplementation could be an effective strategy to reduce As accumulation and toxicity in rice plants.",
Arsenic,1030361,"Ontario gold miners with lung cancer. Occupational exposure assessment in establishing work-relatedness Abstract: Because of inherent errors in exposure data as well as a requirement in the Workers' Compensation Act of Ontario that all claims must be considered on the merits and justice of the individual case, the criteria for assessing work-relatedness of Ontario gold miners who had primary lung cancer could not be based upon any strict occupational exposure criteria. However, a relationship between exposure to silica, arsenic, and radon progeny was derived from results of the epidemiologic studies. A retrospective occupational exposure assessment of silica dust, arsenic, and radon decay products was made in individual cases presented in this paper. The assessment results of 11 gold miners presented in this paper illustrate that the exposure parameters could provide persuasive evidence when the data were consistent with the key epidemiologic findings, eg, the miner's age at first exposure, length of dusty exposure, and latency.",
Arsenic,28337,"Comparison of risks from outdoor and indoor exposure to toxic chemicals Abstract: Environmental Protection Agency TEAM (Total Exposure Assessment Measurement) Studies have measured exposures of about 800 persons to 25 volatile organic compounds (VOCs) and exposures of about 300 persons to 32 pesticides. These persons were selected to represent more than 1 million residents of industrial manufacturing cities such as Bayonne and Elizabeth, New Jersey, and Los Angeles, California; cities with light industry, such as Greensboro, North Carolina, and Baltimore, Maryland; rural areas such as Devils Lake, North Dakota; and cities with high pesticide use such as Jacksonville, Florida, as well as low-to-moderate pesticide use such as Springfield, Massachusetts. The TEAM data provide an opportunity to estimate the risks from airborne exposure to a number of suspected carcinogens for a substantial number of persons residing in a wide variety of urban, suburban, and rural areas. Because all of the TEAM Studies measured outdoor concentrations near the homes of the participants, it is possible to apportion the risks between outdoor and indoor sources. Upper-bound lifetime risks of cancer are calculated for both indoor and outdoor sources of 12 VOCs and about 23 pesticides measured in the TEAM Studies. These risk calculations are supplemented by calculations based on other studies for some additional pollutants, including radon and environmental tobacco smoke. The relationship of these upper-bound risk estimates to ""best-guess"" values is discussed. Sharper estimates of risk based on identifying population subgroups exposed to major sources are also discussed. Important gaps in our knowledge of exposure measurements are identified, e.g., particulates (including polyaromatic hydrocarbons); 1,3-butadiene, asbestos, chromium, cadmium, arsenic, vinyl chloride, methylene chloride, and most polar organics.",
Arsenic,1070440,"Application of classic epidemiological studies and proteomics in research of occupational and environmental exposure to lead, cadmium and arsenic Abstract: The metals/metaloids lead (Pb), cadmium (Cd), and arsenic (As) are among the leading toxic agents in the environment. They represent an important source of dangerous exposure in humans, particularly in industry workers. The most serious consequences of exposure to those heavy metals are cancers and cardiovascular diseases. In studies of human exposure to Pb, Cd, and As alone and in a mixture markers signaling the subtle, early lesions that occur in the human body are still lacking. It is appropriate to develop high throughput techniques and use non-invasive materials. The techniques currently used in classic epidemiological studies allow selection of single markers of changes of exposure to chronic low dose levels of metal/metaloids mixtures. However, application of proteomic techniques in such studies may allow the selection of new biomarkers of environmental and occupational exposure to heavy metals characterized by high sensitivity and specificity. As presented in our review paper, proteomic techniques in combination with appropriate statistical methods allow the selection of potential markers to estimate the changes in the human body when exposed to those heavy metals.",
Arsenic,1018990,"Estimation of the dietary intake of pesticide residues, lead, cadmium, arsenic and radionuclides in France Abstract: Estimation of the dietary exposure of French consumers to 10 pesticides (omethoate, oxydemeton, phosalon, phosphamidon, triazophos, dicofol (op' + pp'), parathion ethyl, dichlorvos, procymidon and vinchlozolin), three heavy metals (lead, cadmium and arsenic) and three radionuclides (134caesium, 137caesium and 131iodine) from collected duplicate portion in mass catering establishments in 1998/1999 are reported, and compared with those from previous French studies as well as those from other countries. Dietary exposure estimates appear to be reassuring, in that Estimated Daily Intake (EDI) estimates are generally low, representing at maximum only 4% of the Acceptable Daily Intake (ADI) for pesticide residues and 28% of the Provisional Tolerable Weekly Intake (PTWI) for heavy metals. Moreover, none of the three radionuclides has been found in duplicate meals. When comparisons are possible, estimated dietary exposures for heavy metals are lower than those from previous French studies and similar or above those from other countries.",
Arsenic,85949,"Biological monitoring of environmental pollution and human exposure to metals in Tarragona, Spain II levels in autopsy tissues Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), vanadium (V), and zinc (Zn) concentrations were determined in brain, bone, kidney, liver, and lung of 20 autopsied subjects nonoccupationally exposed to these elements, who at the time of death had lived in Tarragona (Catalonia, Spain) during at least the last 10 years. Results were analyzed in terms of age, sex, and specific place of residence. Beryllium, Cd, Cr, Mn, Ni, Pb, Tl, Sn, V, and Zn were measured by ICP-MS, whereas As and Hg were determined by using hydride generation-MS. Beryllium, Tl, and V were under the respective detection limits. Bone showed the highest concentrations of As, Cr, Ni, Pb, Sn, and Zn. In turn, the highest levels of Cd and Hg were found in kidney, while liver was the organ with the highest Mn concentrations. For most elements, tissue levels were higher in males than in females. No significant differences",
Arsenic,1103549,"Gallium arsenide selectively up-regulates inflammatory cytokine expression at exposure site Abstract: Gallium arsenide (GaAs), a technologically and economically important semiconductor, is widely utilized in both military and commercial applications. This chemical is a potential health hazard as a carcinogen and immunotoxicant. We previously reported that macrophages at the exposure site exhibit characteristics of activation. In vitro culture of macrophages with GaAs fails to recapitulate the in vivo phenotype, suggesting that complete GaAs-mediated activation in vivo may require other cells or components found in the body's microenvironment. Our present study examined the role of cytokines upon GaAs-mediated macrophage activation. Intraperitoneal administration of GaAs elicited rapid specific recruitment of blood monocytes to the exposure site. This recruitment occurred concomitant with up-regulation of 17 chemokine and inflammatory cytokine mRNAs, while transcripts of three inhibitory cytokines diminished. Administration of latex beads caused less cytokine induction than GaAs, indicating that changes in mRNA levels could not be attributed to phagocytosis. Four representative chemokines and cytokines were selected for further analysis. Increased cytokine mRNA expression was paralleled by similar increases in cytokine protein levels, and secreted protein products were detected in peritoneal fluid. Cytokine protein expression was constrained to myeloid cells, and to a lesser extent to B cells. Alterations in patterns of cytokine gene expression elucidate mechanisms for increased cellular activation and antigen processing, and modulation of the inflammatory response. Our findings indicate that in vivo GaAs exposure alters cytokine gene expression, which may lead to an inflammatory reaction and contribute to pathological tissue damage.",
Arsenic,2345707,"Chelation technique for the removal of heavy metals (As, Pb, Cd and Ni) from green mussel, Perna viridis Abstract: Present research was carried out to study the efficiency of chelation method to remove heavy metals like arsenic (As), lead (Pb), cadmium (Cd) and nickel (Ni) from P. viridis. Chelation method was studied using three types of chelating agents, namely trisodium citrate, disodium oxalate and sodium acetate. Metals concentrations were analysed using ICP-MS technique. Results showed that the sodium acetate gave the highest percentage removal of heavy metals (As 59.50%, Pb 88.57%, Cd 68.01% and Ni 79.67%) followed by disodium oxalate (As 46.89%, Pb 85.46%, Cd 60.41% and Ni 47.80%) and trisodium citrate (As 38.13%, Pb 68.90%, Cd 70.49% and Ni 36.92%). The findings showed that sodium acetate was able to chelate and remove all the studied heavy metals to levels below the permissible limit set forth by Malaysian Food Regulations (1985) and EU Commission Regulation (2006).",
Arsenic,1033692,"Induction of cystine transport in bovine pulmonary artery endothelial cells by sodium arsenite Abstract: Sodium arsenite is one of a number of agents reported to induce a 30-34 kDa 'stress' protein in cells. Other agents which induce this stress protein, including diethyl maleate (DEM) and H2O2, have also been reported to be inducers of cystine transport in fibroblasts, macrophages, endothelial cells and other cell types. We have determined that micromolar levels of sodium arsenite increase cystine transport in bovine pulmonary artery endothelial cells (BPAEC), resulting in increases in intracellular glutathione (GSH). The increase in cystine transport appears to be due to stimulation of the synthesis of a protein analogous to the xc- transport system, a sodium-independent system specific for cystine and glutamate. We have determined that this stimulation is maximal between 8-16 h after addition of sodium arsenite and is inhibited by exogenous GSH. Others have reported that synthesis of the 30-34 kDa stress protein is maximal between 2-4 h and returns to baseline by 6-10 h. We conclude that cystine transport may be considered a 'secondary' stress response and is likely to be modulated by sulfhydryl-reactive agents.",
Arsenic,1346800,"Human TRB3 is upregulated in stressed cells by the induction of translationally efficient mRNA containing a truncated 5'-UTR Abstract: Tribbles homolog 3 (TRB3) is a pseudokinase that has been implicated in the control of stress response, cell viability and metabolic processes, and has been linked to medical conditions, including insulin resistance, cardiovascular disease and diabetes. Therefore, the understanding of mechanisms that regulate TRB3 expression is of considerable importance. We have previously described the existence of several human (h) TRB3 mRNA isoforms that differ in their 5'-untranslated region (5'-UTR). In this study, we use a reverse transcription-quantitative polymerase chain reaction (RT-qPCR) system to characterize the expression levels of hTRB3 mRNA isoforms in HepG2 hepatoma cells cultured in regular medium or exposed to arsenite, and investigate the effect of hTRB3 5'-UTR variants on the efficiency of mRNA translation. The data indicate that of the hTRB3 mRNA splice variants, 1A is predominant (&gt;80% of molecules) in both the stressed and unstressed states, and that the remainder consists mainly of 1B4, with the variants 1B1, 1B2 and 1B3 together forming less than 1% of the population in either condition. In addition to the substantial transcriptional upregulation of all hTRB3 mRNA splice variants, the exposure of cells to arsenite results in a marked increase in the proportion of splice variant 1A molecules containing a truncated 5'-UTR. The shortened 1A 5'-UTR proved to be translationally more efficient than the untruncated 1A 5'-UTR, due to the lack of an inhibitory upstream open reading frame (uORF). Thus, increased transcription as well as altered usage of 5'-UTR variants contributes to the upregulation of hTRB3 protein synthesis in stressful conditions.",
Arsenic,1024624,"The SHEDS-Wood model: Incorporation of observational data to estimate exposure to arsenic for children playing on CCA-treated wood structures Abstract: Background Lumber treated with chromated copper arsenate (CCA) compounds has been used in residential outdoor wood structures and public playgrounds. The U.S. Environmental Protection Agency (EPA) has conducted a probabilistic assessment of children’s exposure to arsenic using the Stochastic Human Exposure and Dose Simulation model for the wood preservative scenario (SHEDS-Wood). The assessment relied on data derived from an experimental study conducted using adult volunteers and designed to result in maximum hand and wipe loadings to estimate the residue–skin transfer efficiency. Recent analyses of arsenic hand-loading data generated by studies of children actively involved in playing on CCA-treated structures indicate that the transfer efficiency coefficient and hand-loading estimates derived from the experimental study significantly overestimate the amount that occurs during actual play. Objectives Our goal was to assess the feasibility of using child hand-loading data in the SHEDS-Wood model and their impact on exposure estimates. Methods We used data generated by the larger of the studies of children in SHEDS-Wood, instead of the distributions used by U.S. EPA. We compared our estimates of the lifetime average daily dose (LADD) and average daily dose (ADD) with those derived by the U.S. EPA. Results Our analysis indicates that data from observational studies of children can be used in SHEDS-Wood. Our estimates of the mean (and 95th percentile) LADD and ADD were 27% (10%) and 29% (15%) of the estimates derived by U.S. EPA. Conclusion We recommend that the SHEDS-Woods model use data from studies of children actively playing on playsets to more accurately estimate children’s actual exposures to CCA.",
Arsenic,2345802,"Prospecting metal-resistant plant-growth promoting rhizobacteria for rhizoremediation of metal contaminated estuaries using Spartina densiflora Abstract: In the salt marshes of the joint estuary of Tinto and Odiel rivers (SW Spain), one of the most polluted areas by heavy metals in the world, Spartina densiflora grows on sediments with high concentrations of heavy metals. Furthermore, this species has shown to be useful for phytoremediation. The total bacterial population of the rhizosphere of S. densiflora grown in two estuaries with different levels of metal contamination was analyzed by PCR denaturing gradient gel electrophoresis. Results suggested that soil contamination influences bacterial population in a greater extent than the presence of the plant. Twenty-two different cultivable bacterial strains were isolated from the rhizosphere of S. densiflora grown in the Tinto river estuary. Seventy percent of the strains showed one or more plant growth-promoting (PGP) properties, including phosphate solubilization and siderophores or indolacetic acid production, besides a high resistance towards Cu. A bacterial consortium with PGP properties and very high multiresistance to heavy metals, composed by Aeromonas aquariorum SDT13, Pseudomonas composti SDT3, and Bacillus sp. SDT14, was selected for further experiments. This consortium was able to two-fold increase seed germination and to protect seeds against fungal contamination, suggesting that it could facilitate the establishment of the plant in polluted estuaries.",
Arsenic,1337510,"Arsenic removal by modified activated carbons with iron hydro(oxide) nanoparticles Abstract: Different activated carbons modified with iron hydro(oxide) nanoparticles were tested for their ability to adsorb arsenic from water. Adsorption isotherms were determined at As (V) concentrations &lt; 1 ppm, with varying pH (6, 7, 8) and temperature (25 and 35 °C). Also, competition effect of anions on the As (V) adsorption capacity was evaluated using groundwater. The surface areas of the modified activated carbons ranged from 632 m(2) g(-1) to 1101 m(2) g(-1), and their maximum arsenic adsorption capacity varied from 370 ?g g(-1) to 1250 ?g g(-1). Temperature had no significant effect on arsenic adsorption; however, arsenic adsorption decreased 32% when the solution pH increased from 6 to 8. In addition, when groundwater was used in the experiments, the arsenic adsorption considerably decreased due to the presence of competing anions (mainly SO(4)(2-), Cl(-) and F(-)) for active sites. The data from kinetic studies fitted well to the pseudo-second-order model (r(2) = 0.98-0.99). The results indicated that sample CAZ-M had faster kinetics than the other two materials in the first 10 min. However, sample F400-M was only 5.5% slower than CAZ-M. The results of this study show that iron modified activated carbons are efficient adsorbents for arsenic at concentrations lower than 300 ?g L(-1).",
Arsenic,1350972,"Transient global cerebral ischemia induces a massive increase in protein sumoylation Abstract: A new group of proteins, small ubiquitin-like modifier (SUMO) proteins, has recently been identified and protein sumoylation has been shown to play a major role in various signal transduction pathways. Here, we report that transient global cerebral ischemia induces a marked increase in protein sumoylation. Mice were subjected to 10 mins severe forebrain ischemia followed by 3 or 6 h of reperfusion. Transient cerebral ischemia induced a massive increase in protein sumoylation by SUMO2/3 both in the hippocampus and cerebral cortex. SUMO2/3 conjugation was associated with a decrease in levels of free SUMO2/3. After ischemia, protein levels of the SUMO-conjugating enzyme Ubc9 were transiently decreased in the cortex but not in the hippocampus. We also exposed HT22 cells to arsenite, a respiratory poison that impairs cytoplasmic function and induces oxidative stress. Arsenite exposure induced a marked rise in protein sumoylation, implying that impairment of cytoplasmic function and oxidative stress may be involved in the massive post-ischemic activation of SUMO conjugation described here. Sumoylation of transcription factors has been shown to block their activation, with some exceptions such as the heat-shock factor and the hypoxia-responsive factor, where sumoylation blocks their degradation, and the nuclear factor-kappaB (NF-kappaB) essential modulator where sumoylation leads to an activation of NF-kappaB. Because protein sumoylation is known to be involved in the regulation of various biologic processes, the massive post-ischemic increase in protein sumoylation may play a critical role in defining the final outcome of neurons exposed to transient ischemia.",
Arsenic,1019148,"Effects of arsenic, cadmium, chromium, and lead on gene expression regulated by a battery of 13 different promoters in recombinant HepG2 cells Abstract: Toxic metals occur naturally at low concentrations throughout the environment, but are found in higher concentrations at many of the hazardous waste sites on the EPA Superfund list. As part of the Agency for Toxic Substances and Disease Registry (ATSDR) mandate to evaluate the toxicity of metals and mixtures, we chose four of the high-priority metal pollutants from ATSDR's HAZDAT list, including arsenic, cadmium, chromium, and lead, to test in a commercially developed assay system, CAT-Tox(L) (Xenometrix). This assay employs a battery of recombinant HepG2 cell lines to test the transcriptional activation capacity of xenobiotics in any of 13 different signal transduction pathways. Our specific aims were to identify metal-responsive promoters and determine whether the pattern of gene expression changed with a mixture of metals. Humic acid was used in all assays as a carrier to help solubilize the metals and, in all cases, the cells were exposed to the humic acid-metal mixture for 48 h. Humic acid alone, at 50-100 microM, showed moderate activation of the XRE promoter, but little other notable activity. As(V), at doses of 50-250 microM, produced a complex profile of activity showing significant dose-dependent induction of the hMTIIA, GST Ya, HSP70, FOS, XRE, NFkappaBRE, GADD153, p53RE, and CRE promoters. Pb(II) showed dose-related induction of the GST Ya, XRE, hMTIIA, GRP78, and CYP IA1 promoters at doses in the range of 12-100 microM. Cd(II), at 1.25-15 microM, yielded significant dose-dependent induction of hMTIIA, XRE, CYP IA1, GST Ya, HSP70, NFkappaBRE, and FOS. Whereas Cr(III) yielded small, though significant inductions of the CRE, FOS, GADD153, and XRE promoters only at the highest dose (750 microM), Cr(VI) produced significant dose-related inductions of the p53RE, FOS, NFkappaBRE, XRE, GADD45, HSP70, and CRE promoters at much lower doses, in the range of 5-10 microM. Assays testing serial dilutions of a mixture comprising 7.5 microM Cd(II), 750 microM Cr(III), and 100 microM Pb(II) (the combination of metals most frequently found at National Priority List sites) showed significant dose-dependent induction of the hMTIIA promoter, but failed to show dose-related induction of any other promoter and showed no evidence of synergistic activation of gene expression by the metals in this mixture. Our results thus show metal activation of gene expression through several previously unreported signal transduction pathways, including As(V) induction of GST Ya, FOS, XRE, NFkBRE, GADD153, p53RE, and CRE; Pb(II) induction of GST Ya, XRE, Cyp IA1, and GADD153; Cd(II) induction of NFkBRE, Cyp IA1, XRE, and GST Ya; and Cr(VI) induction of p53RE, XRE, GADD45, HSP70, and CRE promoters, and thus suggest new insights into the biochemical mechanisms of toxicity and carcinogenicity of metals. It is also an important finding that no evidence of synergistic activity was detected with the mixture of Cd(II), Cr(III), and Pb(II) tested in these assays.",
Arsenic,1359548,"Response to CHO cell proliferation and histone phosphorylation to sodium arsenite Abstract: HEEP COPYRIGHT: BIOL ABS. Because of the causal association between arsenic and cancer in humans, studies were initiated to determine whether low levels of arsenic affect cell proliferation and chromatin constituents. Cultured CHO (hamster ovary) cells were treated with As(III) or As(V) in the form of sodium arsenite (NaAsO2) or sodium arsenate (Na2HAsO4), respectively. Arsenite was 10 times more toxic than arsenate; 50 muM arsenite caused irreversible inhibition of culture growth. At lower concentrations, 10 muM NaAsO2 induced culture growth kinetics that were radiomimetic, i.e., caused a cell division delay period followed by spontaneous recovery of cell division in the continued presence of the arsenite. During this division delay, histone HI phosphorylation was reduced to 40% of the control level. It recovered to the control level just before recovery of cell division. Histone H2A phosphorylation was stimulated in the middle of the delay period, followed by stimulation of H3 phosphorylation just before recovery of cell division. ATP pool levels were unaffected at these low arsenite concentrations. The DNA synthesis rate was reduced during division delay, but did not recover immediately before resumption of cell division. Arsenite uncoupled H1 phosphorylation from DNA synthesis. Flow microfluorometric analysis showed that cell cycle progression was inhibited in G1, S and G2 during the division delay period. On recovery of cell division, cells in S and G2 regained the capacity to resume cycle traverse earlier than did cells in G1. Part of the reduced rate of DNA synthesis observed on resumption of cell division results from the failure of G1 cells to resume initiation of S phase at the same time that S and G2 cells begin cell cycle traverse. Cell survival studies indicated that 89% of the cells survived 24-h treatment with 10 muM NaAsO2. The spontaneous recovery of cell proliferation and high survival rate of arsenite-treated cells indicate a need to determine whether the perturbations in histone and DNA metabolism caused by arsenite result in any genetic damage that could be transferred to future cell generations.",
Arsenic,1342785,"ENHANCED HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-I EXPRESSION FOLLOWING INDUCTION OF THE CELLULAR STRESS-RESPONSE Abstract: Human T-cell lymphotropic virus type I (HTLV-I) infection is typically associated with long incubation periods between virus exposure and disease manifestation. Although viral protein expression is considered to play an important role in the pathogenesis of HTLV-I-associated diseases, limited information is known regarding host cell mechanisms that control viral gene expression. This study was designed to evaluate modulation of HTLV-I gene expression following induction of the cellular stress response in HTLV-I-infected lymphocytes. The cellular stress response was elicited by treatment with either Na arsenite or thermal stress and was monitored by demonstrating increased expression of the 72-kDa heat shock protein. Induction of the cellular stress response in HTLV-I-infected lymphocytes resulted in significantly increased HTLV-I-mediated syncytia formation due to enhanced HTLV-I envelope (gp46) expression. Intracellular viral proteins and released p24 capsid protein were increased in stressed infected lymphocytes as compared to nonstressed infected lymphocytes. Furthermore, HTLV-I-LTR reporter gene constructs had increased activity (three- to sixfold) in a transiently transfected, uninfected lymphocyte cell line following induction of the cellular stress response. Quantitation of HTLV-I RNA expression by slot blot analysis of infected lymphocytes suggested variable increases in RNA accumulation. Northern blot analysis demonstrated no qualitative changes in expression of RNA species. These data suggest a relationship between modulation of viral replication and a basic cellular response to stress and have important implications for understanding host cell control mechanisms of HTLV-I expression.",
Arsenic,1357660,"Mutation and Neoplastic Transformation. Correlations and Dissociations Abstract: The somatic mutation theory of carcinogenesis has been used as the basis for most short term tests for carcinogens. Good experimental data supported this theory based on molecular and cytogenic analysis of mutational changes in tumors. Even so, certain chemicals have been defined as nonmutagenic carcinogens. Several mechanisms for the lack of detectable mutagenic activity of these carcinogens were discussed. One example was amitrole (61825), which was inactive as a mutagen in bacterial test systems, but was mutagenic in Syrian-hamster embryo cells. The organotropism of amitrol was explained by the metabolic activation of this chemical to reactive intermediates in combination with a hormone like action on the thyroid. Other apparent exceptions to the correlation between carcinogenicity and mutagenicity such as benzene (71432), arsenic (7440382), diethylstilbestrol (56531), and asbestos (1332214) may involve the ability of certain chemicals to act specifically as chromosome mutagens. The methylation of DNA at the 5 position of cytosine was found to be important in the regulation of gene expression and was one possible mechanism for the heritable change in cancer cells that does not require a direct interaction between the carcinogen and DNA. Some chemicals exerted a carcinogenic effect due in part to their tumor promoting activity. Such activity should not be viewed as mutually exclusive of genetic activity in the same chemical.",
Arsenic,1337528,"Levels of heavy metals in tissues of shingi fish (Heteropneustes fossilis) from Buriganga River, Bangladesh Abstract: Heavy metal pollution was reported in commercially valuable freshwater edible fish in the Buriganga River, Bangladesh. The concentrations of As, Pb, Cd, Cr, Zn, and Cu were investigated in the muscle, gill, stomach, intestine, and liver of Heteropneustes fossilis caught at three stations to assess the degree of fish pollution by heavy metals. Significant differences in concentrations of analyzed elements were observed among different tissues, but not among the stations. The ranges of the measured concentrations (?g/g dry weight) in the tissues of H. fossilis were as follows: arsenic concentration was (0.2-0.4), (0.82-0.90), (3.29-3.99), (2.20-2.80), and (2.41-2.90), that of lead was (1.79-2.20), (4.95-6.55), (10.36-13.38), (5.74-9.70), and (18.20-18.79), that of cadmium was (0.3-0.4), (2.87-4.27), (1.03-1.63), (1.55-4.59), and (2.25-5.50), that of chromium was (1.40-1.70), (3.52-3.72), (2.28-5.29), (2.77-3.79), and (4.25-8.65), that of zinc was (24.47-28.82), (16.82-18.80), (20.22-22.20), (22.86-26.68), and (60.82-67.80), and that of copper was (7.80-8.50), (6.22-6.81), (38.21-44.25), (17.07-21.03), and (43.24-47.30) in the muscle, gill, stomach, intestine, and liver, respectively. This research showed that the liver appeared to be the main heavy metal storage tissue, while the muscle had the lowest levels of analyzed metals. The concentrations of metal in the muscles not exceeded the acceptable levels for a food source for human consumption.",
Arsenic,1172214,"Environmental Arsenic Concentrations Alter Calcium Signaling And Wound Repair In Lung Epithelial Cells Abstract: Epidemiological evidence implicates arsenic exposure in increased incidence of lung cancer and chronic lung disease. While chronic exposure to moderate and/or high levels of arsenic in drinking water may lead to the development of lung injury in humans, the effects at low dose are inferred only through models of high exposure dose. To further explore arsenic-induced alterations, we exposed confluent bronchial airway epithelial cell cultures (16HBE) to 25, 50, 100 ppb and 500 ppb arsenite and monitored wound healing and associated intracellular Ca2+ concentration ([Ca2+]i) changes. Following a 24 exposure to arsenic, the ability of the cells to undergo mechanical wound repair was inhibited by arsenic exposures of 50 ppb and greater. Mechanical wounding results in a coordinated increase in [Ca2+]i among neighboring cells (calcium wave). Arsenic at 100 ppb resulted in a slight decrease in the number of cells involved in the calcium wave. However, the difference was not significant. Because wound-induced calcium signaling is blocked by apyrase, we also tested whether arsenite treated cells displayed altered responses to purinergic agonists. Treatment with 100 ppb arsenite for 24 hours resulted in a significant reduction in the number of cells responding to ATP stimulation. Over 50% of untreated cells responded with increased [Ca2+]i after stimulation with 1 uM ATP. 100 ppb arsenite treatment reduced the percentage of responding cells to 20%. While over 30% of cells responded to 500 nM ATP stimulation, this was reduced to 4% in arsenic treated cells. Taken together, these data indicate that environmental levels of arsenic can reduce purinergic dependent [Ca2+]i signaling and wound healing in human bronchial epithelial cells.",
Arsenic,1508578,"Arsenite-induced changes in abundance and expression of arsenite transporter and arsenite oxidase genes of a soil microbial community Abstract: We describe a real-time PCR assay for the quantitative detection of arsB and ACR3(1) arsenite transporter gene families, two ubiquitous and key determinants of arsenic resistance in prokaryotes. The assay was applied in batch growth experiments using a wasteland soil bacterial community as an inoculum to investigate the effect of increasing arsenite [As(III)] concentrations on genes and transcript abundances. The aioA gene encoding the large subunit of arsenite oxidase was monitored in parallel. Results showed that arsB and ACR3(1) gene abundances correlated positively with the As(III) concentration. Both genes showed similar transcription patterns and strong upregulation by arsenic. Microbial As(III) oxidation occurred in As(III) spiked cultures and was associated with expression of the aioA gene in most cases. However, aioA was also expressed in several non-amended culture replicates. Analysis of cDNA clone libraries revealed that Pseudomonas was the dominant metabolically active genus whatever the As(III) concentration. Expressed arsB and ACR3(1) gene sequences were also affiliated with those from Pseudomonas, while expressed aioA sequences were more taxonomically diverse. The study suggests that arsenite transporter genes are appropriate biomarkers of arsenic stress that may be suitable for further exploring the adaptive response of bacterial communities to arsenic in contaminated environments.",
Arsenic,1597313,"Effects of sodium arsenite on neurite outgrowth and glutamate AMPA receptor expression in mouse cortical neurons Abstract: There has been broad concern that arsenic in the environment exerts neurotoxicity. To determine the mechanism by which arsenic disrupts neuronal development, primary cultured neurons obtained from the cerebral cortex of mouse embryos were exposed to sodium arsenite (NaAsO2) at concentrations between 0 and 2?M from days 2 to 4 in vitro and cell survival, neurite outgrowth and expression of glutamate AMPA receptor subunits were assessed at day 4 in vitro. Cell survival was significantly decreased by exposure to 2?M NaAsO2, whereas 0.5?M NaAsO2 increased cell survival instead. The assessment of neurite outgrowth showed that total neurite length was significantly suppressed by 1?M and 2?M NaAsO2, indicating that the lower concentration of NaAsO2 impairs neuritogenesis before inducing cell death. Immunoblot analysis of AMPA receptor subunit expression showed that the protein level of GluA1, a specific subunit of the AMPA receptor, was significantly decreased by 1?M and 2?M NaAsO2. When immunocytochemistry was used to confirm this effect by staining for GluA1 expression in neuropeptide Y neurons, most of which contain GluA1, GluA1 expression in neuropeptide Y neurons was found to be significantly suppressed by 1?M and 2?M NaAsO2 but to be increased at the concentration of 0.5?M. Finally, to determine whether neurons could be rescued from the NaAsO2-induced impairment of neuritogenesis by compensatory overexpression of GluA1, we used primary cultures of neurons transfected with a plasmid vector to overexpress either GluA1 or GluA2, and the results showed that GluA1/2 overexpression protected against the deleterious effects of NaAsO2 on neurite outgrowth. These results suggest that the NaAsO2 concentration inducing neurite suppression is lower than the concentration that induces cell death and is the same as the concentration that suppresses GluA1 expression. Consequently, the suppression of GluA1 expression by NaAsO2 seems at least partly responsible for neurite suppression induced by NaAsO2.",
Arsenic,1354902,"THE ROLE OF THE MATRIX CALCIUM LEVEL IN THE ENHANCEMENT OF MITOCHONDRIAL PYRUVATE CARBOXYLATION BY GLUCAGON PRETREATMENT Abstract: The effect of Ca2+ on the rate of pyruvate carboxylation was studied in liver mitochondria from control and glucagon-treated rats, prepared under conditions that maintain low Ca2+ levels (1-3 nmol/mg of protein). When the matrix-free [Ca2+] was low (less than 100 nM), the rate of pyruvate carboxylation was not significantly different in mitochondria from control and glucagon-treated rats. Accumulation of 5-8 nmol of Ca2+/mg, which increased the matrix [Ca2+] to 2-5 microM in both preparations, significantly enhanced pyruvate carboxylase flux by 20-30% in the mitochondria from glucagon-treated rats, but had little effect in control preparations. Higher levels of Ca2+ (up to 75 nmol/mg) inhibited pyruvate carboxylation in both preparations, but the difference between the mitochondria from control and glucagon-treated animals was maintained. The enhancement of pyruvate dehydrogenase flux by mitochondrial Ca2+ uptake was also significantly greater in mitochondria from glucagon-treated rats. These differential effects of Ca2+ uptake on enzyme fluxes did not correlate with changes in the mitochondrial ATP/ADP ratio, the pyrophosphate level, or the matrix volume. Arsenite completely prevented 14CO2 incorporation when pyruvate was the only substrate, but caused only partial inhibition when succinate and acetyl carnitine were present as alternative sources of energy and acetyl-CoA. Under these conditions, mitochondria from glucagon-treated rats were less sensitive to arsenite than the control preparations, even at low Ca2+ levels. We conclude that the Ca(2+)-dependent enhancement of pyruvate carboxylation in mitochondria from glucagon-treated rats is a secondary consequence of pyruvate dehydrogenase activation; glucagon treatment is suggested to affect the conditions in the mitochondria that change the sensitivity of the pyruvate dehydrogenase complex to dephosphorylation by the Ca(2+)-sensitive pyruvate dehydrogenase phosphatase.",
Arsenic,1027337,"OCCURRENCE OF GERMANIUM AND ARSENIC IN METEORITES Abstract: 1. Spectroscopic evidence has been obtained of the occurrence of germanium in certain siderites, siderolites and aerolites. 2. Judging from the number and intensity of spectral lines the germanium in these meteorites is present in traces. 3. Germanium has been extracted from Toluca and Welland siderites. 4. Arsenic has been extracted from Toluca and Welland siderites.",
Arsenic,1520114,The endocrine disruptors cadmium chloride and sodium arsenate induce human lung adenocarcinoma cell proliferation by activating the estrogen receptor-mediated signaling pathway Abstract: ,
Arsenic,1797781,"Trace elements in animal-based food from Shanghai markets and associated human daily intake and uptake estimation considering bioaccessibility Abstract: The concentrations of four human essential trace elements [iron (Fe), manganese (Mn), zinc (Zn), chromium (Cr)] and non-essential elements [cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg)] in eighteen animal-based foods including meat, fish, and shellfish collected from markets in Shanghai, China, were analyzed, and the associated human daily intake and uptake considering bioaccessibility were estimated. The mean concentration ranges for eight trace elements measured in the foods were 3.98-131µgg(-1) for Fe, 0.437-18.5µgg(-1) for Mn, 5.47-53.8µgg(-1) for Zn, none detected-0.101µgg(-1) for Cr, 2.88×10(-4)-2.48×10(-2)µgg(-1) for Cd, 1.18×10(-3)-0.747µgg(-1) for Pb, none detected-0.498µgg(-1) for As, and 8.98×10(-4)-6.52×10(-2)µgg(-1) for Hg. The highest mean concentrations of four human essential elements were all found in shellfish. For all the trace elements, the observed mean concentrations are mostly in agreement with the reported values around the world. The total daily intake of trace elements via ingestion of animal-based food via an average Shanghai resident was estimated as 7371µgd(-1) for the human essential elements and 13.0µgd(-1) for the human non-essential elements, but the uptake decreased to 4826µgd(-1) and 6.90µgd(-1), respectively, after trace element bioaccessibility was considered. Livestock and fish for human essential and non-essential elements, respectively, were the main contributor, no matter whether the bioaccessibility was considered or not. Risk estimations showed that the intake and uptake of a signal trace element for an average Shanghai resident via ingestion animal-based foods from Shanghai markets do not exceed the recommended dietary allowance values; consequently, a health risk situation is not indicated.",
Arsenic,1349290,Synthesis of Mesostructured Iron Oxides with Potential As(V) Adsorption Application Abstract: ,
Arsenic,2337120,"Toxic and micronutrient elements in organic, brown and polished rice in Brazil Abstract: Concentration levels of As, Cd, Hg, Pb, Tl, Sn, Sb Co, Cu, Mn, Se, Zn, Cr, Ni and Mo in different types of rice cultivated in irrigated fields in Brazil were evaluated. Arsenic, Cd, Pb, Zn, Mn and Cu were found in higher concentrations in brown rice samples, suggesting the prevalence of these elements in the bran. Meanwhile, lower concentrations of Pb, Mo, Cr, Se and Co were found in parboiled rice. Organic rice did not differ of cultivated conventionally rice. Thallium, Hg and Sb were not detected in any rice sample whose limits of detection were 0.7 ?g kg(-1), 2.5 ?g kg(-1) and 8 ?g kg(-1), respectively. The concentrations of the investigated elements were compared with those reported for polished rice and brown rice from other countries, unveiling concentrations in general at the same level for rice produced at non-contaminated sites.",
Arsenic,2278438,"Comparison of As sequestration in iron plaque and uptake by different genotypes of rice plants grown in As-contaminated paddy soils Abstract: Limited information is available on comparing the iron plaque formation capabilities and their effect on arsenic (As) uptake by different rice plant genotypes grown in As-contaminated soils. This study investigates the effect of iron plaque on As uptake in different rice genotypes grown in As-contaminated soils from the Guandu Plain of northern Taiwan. <br> <br>Twenty-eight rice genotypes including 14 japonica and 14 indica genotypes were used in this study. Rice seedlings were grown in As-contaminated soils for 38 days. The iron plaque formed on the rice roots were extracted using dithionite-citrate-bicarbonate. The concentrations of As, Fe, and P in soil solutions, iron plaque, and plants were measured. The speciation of As in the root's iron plaque was determined by As K-edge X-ray absorption near-edge structure spectroscopy (XANES). <br> <br>The amounts of iron plaque formation on roots were significantly different among 28 tested rice genotypes, and 75.7-92.8 % of As uptake from soils could be sequestered in iron plaque. However, there were no significant negative correlations between the amounts of Fe or As in the iron plaque and the content of As accumulated in rice plants of tested genotypes. XANES data showed that arsenate was the predominant As species in iron plaque, and there were difference in the distribution of As species among different rice genotypes. <br> <br>The iron plaque can sequester most of As uptake from soils no matter what rice genotypes used in this study. However, the iron plaque alone did not control the extent of As accumulation in rice plants from As-contaminated soils among 28 tested rice genotypes. Low As uptake genotypes of rice selected from this study can be recommended to be grown in the As-contaminated soils.",
Arsenic,627267,"Arsenic trioxide induces selective tumour vascular damage via oxidative stress and increases thermosensitivity of tumours Abstract: It has previously been found that the anti-leukaemia agent Arsenic Trioxide (ATO) causes vascular shutdown in solid tumours and markedly sensitizes tumours to hyperthermia. The present study was designed to evaluate the mechanism of action and dose-dependence of ATO-induced thermosensitization in FSaII and SCK murine tumours. The role of oxidative stress was studied by observing ATO-induced vascular shutdown in vivo and ATO-induced endothelial cell adhesion molecule expression in vitro in the presence or absence of an anti-oxidant. It was found that a dose as low as 2 mg/kg ATO impaired vascular function, as estimated by 86Rb uptake, in the tumour. The degree of tumour growth delay induced by 1 h of hyperthermia at 42.5 degrees C, applied 2 h after ATO injection, was proportional to the dose of ATO administered. In addition, it was found that ATO can directly thermosensitize tumour cells in vitro. The development of massive tissue necrosis in the tumour was observed in the days after treatment, especially with the combination of ATO and heating. ATO-induced adhesion molecule expression in vitro was abolished when the anti-oxidant n-acetyl-cysteine (NAC) was introduced prior to exposure, while the addition of NAC in vivo partially blocked ATO-induced vascular shutdown. These results suggest that the expression of adhesion molecules by the vasculature due to oxidative stress contribute to the ATO-induced selective tumour vascular effects observed and that the clinical use of ATO to increase tumour thermosensitivity via direct cellular and vascular effects appears feasible.",
Arsenic,1508595,"Genetic Determinants for Cadmium and Arsenic Resistance among Listeria monocytogenes Serotype 4b from Sporadic Human Listeriosis Abstract: In Listeria monocytogenes serotype 4b from sporadic listeriosis, heavy metal resistance was primarily encountered in certain clonal groups (ECI, ECII, ECIa). All arsenic-resistant isolates harbored the arsenic resistance cassette previously identified in pLI100; ECIa harbored additional arsenic resistance genes and a novel cadmium resistance determinant in a conserved chromosomal locus.",
Arsenic,1353071,Arsenic dopant mapping in state-of-the-art semiconductor devices using electron energy-loss spectroscopy Abstract: ,
Arsenic,8598,"Cancer potential in liver, lung, bladder and kidney due to ingested inorganic arsenic in drinking water Abstract: In order to compare risk of various internal organ cancers induced by ingested inorganic arsenic and to assess the differences in risk between males and females, cancer potency indices were calculated using mortality rates among residents in an endemic area of chronic arsenicism on the southwest coast of Taiwan, and the Armitage-Doll multistage model. Based on a total of 898,806 person-years as well as 202 liver cancer, 304 lung cancer, 202 bladder cancer and 64 kidney cancer deaths, a significant dose-response relationship was observed between arsenic level in drinking water and mortality of the cancers. The potency index of developing cancer of the liver, lung, bladder and kidney due to an intake of 10 micrograms kg day of arsenic was estimated as 4.3 x 10(-3), 1.2 x 10(-2), 1.2 x 10(-2), and 4.2 x 10(-3), respectively, for males; as well as 3.6 x 10(-3), 1.3 x 10(-2), 1.7 x 10(-2), and 4.8 x 10(-3), respectively, for females in the study area. The multiplicity of inorganic arsenic-induced carcinogenicity without showing any organotropism deserves further investigation.",
Arsenic,1936175,"Groundwater arsenic in the fluvial Bengal plains: Geochemistry and mitigation  Abstract: The water quality and chemistry of the groundwater of the fluvial Bengal plains have been investigated. It has been found that shallow aquifers (< 50 m bgl) are contaminated in a few pockets, surrounded by areas with low arsenic (As)/As-free groundwater, while the deeper aquifer (> 100 m bgl) is generally free from As (< 10 ?g/L). It also reveals that multiple As mobilization processes are occurring simultaneously, rather than any single geochemical process. An attempt has been made to demonstrate the degree of As heterogeneity with groundwater quality, and this has been followed by a few local conditions. The study further suggests that the As distribution (spatio-vertical) helps to identify safe shallow aquifers, and several signatures (colour of the sediments/land use pattern/geomorphological features/local recharge events) are apparent that can be useful for formulating long-term mitigation options.",
Arsenic,734873,"Increased childhood liver cancer mortality and arsenic in drinking water in northern Chile Abstract: Arsenic in drinking water is an established cause of lung, bladder, and skin cancers in adults and may also cause adult kidney and liver cancers. Some evidence for these effects originated from region II of Chile, which had a period of elevated arsenic levels in drinking water, in particular from 1958 to 1970. This unique exposure scenario provides a rare opportunity to investigate the effects of early-life arsenic exposure on childhood mortality; to our knowledge, this is the first study of childhood cancer mortality and high concentrations of arsenic in drinking water. In this article, we compare cancer mortality rates under the age of 20 in region II during 1950 to 2000 with those of unexposed region V, dividing subjects into those born before, during, or after the peak exposure period. Mortality from the most common childhood cancers, leukemia and brain cancer, was not increased in the exposed population. However, we found that childhood liver cancer mortality occurred at higher rates than expected. For those exposed as young children, liver cancer mortality between ages 0 and 19 was especially high: the relative risk (RR) for males born during this period was 8.9 [95% confidence interval (95% CI), 1.7-45.8; P = 0.009]; for females, the corresponding RR was 14.1 (95% CI, 1.6-126; P = 0.018); and for males and females pooled, the RR was 10.6 (95% CI, 2.9-39.2; P &lt; 0.001). These findings suggest that exposure to arsenic in drinking water during early childhood may result in an increase in childhood liver cancer mortality.",
Arsenic,2343536,"An overview of the role of goethite surfaces in the environment Abstract: Goethite, one of the most thermodynamically stable iron oxides, has been extensively researched especially the structure (including surface structure), the adsorption capacity to anions, organic/organic acid (especially for the soil organic carbon) and cations in the natural environment and its potential application in environmental protection. For example, the adsorption of heavy metals by goethite can decrease the concentration of heavy metals in aqueous solution and immobilize; the adsorption to soil organic carbon can decrease the release of carbon and fix carbon. In this present overview, the possible physicochemical properties of the goethite surface contributing to the strong affinity of goethite to nutrients and contaminants in natural environment are reported. Moreover, these chemicals adsorbed by goethite were also summarized and the suggested adsorption mechanism for these adsorbates was elucidated, which will help us understand the role of goethite in natural environment and provide some information about goethite as an absorbent. In addition, the feasibility of goethite used as catalyst carrier and the precursor of NZVI was proposed for removal of environmental pollution. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,1356797,"Cell-cycle dependence of the cytotoxicity and clastogenicity of sodium arsenite in Chinese hamster ovary cells Abstract: The cell-cycle time of the replated shake-off mitotic cells was determined to be 16 h, with an G1 of 6h, an S of 6h and G2 plus mitosis of 4h. Cells at early G1 were the most sensitive to the killing and mitotic inhibition of sodium arsenite. Whereas, the highest clastogenicity of sodium arsenite was detected at G1/S border. Sodium arsenite may be classified as an S-dependent clastogen, because the aberrations induced were mainly chromatid breaks and chromatid exchanges, when the cells were treated with sodium arsenite in G1 and early S phases.",
Arsenic,627201,"Comparison of tissue dosimetry in the mouse following chronic exposure to arsenic compounds Abstract: Several chronic bioassays have been conducted in multiple strains of mice in which various concentrations of arsenate or arsenite were administered in the drinking water without a tumorigenic effect. However, one study (Ng et al., 1999) reported a significant increase in tumor incidence in C57Bl/6J mice exposed to arsenic in their drinking water throughout their lifetime, with no tumors reported in controls. A physiologically based pharmacokinetic model for arsenic in the mouse has previously been developed (Gentry et al., 2004) to investigate potential differences in tissue dosimetry of arsenic species across various strains of mice. Initial results indicated no significant differences in blood, liver, or urine dosimetry in B6C3F1 and C57Bl/6 mice for acute or subchronic exposure. The current work was conducted to compare model-predicted estimates of tissue dosimetry to additional kinetic information from the (C57Bl/6 xCBA)F1 and TgAc mouse. The results from the current modeling indicate that the pharmacokinetic parameters derived based on information in the B6C3F1 mouse adequately describe the measured concentrations in the blood/plasma, liver, and urine of both the (C57Bl/6 x CBA)F1 and TgAc mouse, providing further support that the differences in response observed in the chronic bioassays are not related to strain-specific differences in pharmacokinetics. One significant finding was that no increases in skin or lung concentrations of arsenic species in the (C57Bl/6 x CBA)F1 strain were observed following administration of low concentrations (0.2 or 2 mg/U of arsenate in the drinking water, even though differences in response in the skin were reported. These data suggest that pharmacodynamic changes may be observed following exposure to arsenic compounds without an observable change in tissue dosimetry. These results provided further indirect support for the existence of inducible arsenic efflux in these tissues.",
Arsenic,1579378,"Effects of diphenylarsinic acid on bacterial and archaeal community structures in an anaerobic paddy soil Abstract: DPAA is often found as one of the major degradation products in soil and groundwater contaminated with diphenylcyanoarsine or diphenylchloroarsine. These compounds were produced mainly during the World Wars as chemical warfare agents. This study investigated the effect of DPAA contamination on soil bacterial and archaeal community structures under anaerobic conditions in a model experiment using 16S rRNA targeted PCR-DGGE fingerprinting of DNA extracted from the contaminated soil. DPAA decreased in anaerobically incubated soil cultures due to microbiological activity. Addition of rice straw partially enhanced the extent of DPAA degradation. Inorganic arsenic acid, PM, and an unknown arsenical species were detected as degradation products using LC-ICPMS. PCR-DGGE fingerprinting for bacterial community analysis revealed that anaerobic bacterial and archaeal species, including Clostridium and Methanosarcina, became abundant in the incubated soil within a week. In the soil cultures incubated with DPAA, while a few bacterial bands found on the DGGE gels disappeared or became weaker, most of the bands showed no significant changes. Addition of DPAA had no significant effect on archaeal communities. These findings suggest that, even though DPAA may have a direct effect on some abundant bacterial species, overall bacterial and archaeal community structures under the anaerobic soil conditions tended to be stable regardless of DPAA contamination. (c) 2012 Elsevier B.V. All rights reserved.",
Arsenic,2347677,"Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: Implications for emission management and human health Abstract: Mining operations, including crushing, grinding, smelting, refining, and tailings management, are a significant source of airborne metal and metalloid contaminants such as As, Pb and other potentially toxic elements. In this work, we show that size-resolved concentrations of As and Pb generally follow a bimodal distribution with the majority of contaminants in the fine size fraction (&lt;1?m) around mining activities that include smelting operations at various sites in Australia and Arizona. This evidence suggests that contaminated fine particles (&lt;1?m) are the result of vapor condensation and coagulation from smelting operations while coarse particles are most likely the result of windblown dust from contaminated mine tailings and fugitive emissions from crushing and grinding activities. These results on the size distribution of contaminants around mining operations are reported to demonstrate the ubiquitous nature of this phenomenon so that more effective emission management and practices that minimize health risks associated with metal extraction and processing can be developed.",
Arsenic,1508614,"Oxidation of carbene-stabilized diarsenic: Diarsene dications and diarsenic radical cations Abstract: Oxidation of carbene-stabilized diarsenic, L:As-As:L [L: = :C{N(2,6-(i)Pr(2)C(6)H(3))CH}(2)] (1), with gallium chloride in a 1:4 ratio in toluene affords the dicationic diarsene complex [L:As?As:L](2+)([GaCl(4)](-))(2) (2(2+)[GaCl(4)](2)), while oxidation of 1 with GaCl(3) in a 1:2 ratio in Et(2)O yields the monocationic diarsenic radical complex [L:AsAs:L](•+)[GaCl(4)](-) (2(•+)[GaCl(4)]). Strikingly, complex 2(•+) is the first arsenic radical to be structurally characterized in the solid state. The nature of the bonding in these complexes was probed computationally and spectroscopically.",
Arsenic,1017594,"Urinary arsenic concentrations and speciation in residents living in an area with naturally contaminated soils Abstract: A cross sectional study was carried out to evaluate arsenic exposure of residents living in an area with a soil naturally rich in arsenic (As), through urinary measurements. During the summer of 2007, 322 people aged over 7 years and resident in the study area for at least 4 days prior to the investigation were recruited. The sum of urinary inorganic arsenic and metabolites (iAs+MMA+DMA) and speciation were determined by graphite furnace atomic absorption spectrometry and high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry, respectively. Geometric means levels of iAs+MMA+DMA were 3.6 microg/L or 4.4 microg/g creatinine. The percent of DMA, As(III) and MMA contribution to urinary arsenic concentrations was respectively 84.2%, 12% and 3.7%. We found significant associations between urinary arsenic concentrations and the consumption of seafood (p=0.03), the consumption of wine (p=0.03) and beer (p=0.001), respectively 3 and 4 days before the investigation. When we focus on the various species, As(V) was rarely detected and DMA is the predominant metabolite composing the majority of measurable inorganic-related As in the urine. Considering the percent of DMA contribution to iAs+MMA+DMA urinary concentrations, almost half of the subjects had 100% of DMA contribution whatever the concentration of urinary As whereas the others had a lower DMA contribution, between 39 and 90%. Arsenic levels reported in this original study in France were between 2 and 4 times lower than in other studies dealing with iAs+MMA+DMA levels associated with soil arsenic exposure. Arsenic levels were similar to those observed in unexposed individuals in European countries, although 10% were above the French guideline values for the general population.",
Arsenic,2345831,"Surface rearrangement of nanoscale zerovalent iron: The role of pH and its implications in the kinetics of arsenate sorption Abstract: We consider the use of metallic iron nanoparticles for cleaning contaminated water, focusing our study in the sorption of arsenic compounds. In particular, we discuss the results of their sorption process on the surface of zerovalent iron nanoparticles (nZVI) by performing a complete characterization of the surface modifications. Using scanning electron microscopy, X-ray diffraction analysis and high-resolution transmission electron microscopy, spectroscopy diffraction measurements and elemental mapping, we typify the surface reconstruction during the sorption process of As(V) from aqueous solutions using nZVI when it goes into a crystalline parasymplesite structure. The experimental results were correlated to the Freundlich isotherm sorption where the sorption capacity is depleted by the increase in the pH from 4 to 7 and associated with the surface passivation of nZVI. These techniques confirm the dependence of the sorption of arsenic as a function of pH and describe the specific details on the modification of the surface area of the nanoparticles.",
Arsenic,2088486,"In-vivo evaluation of the permeability of the blood-brain barrier to arsenicals, molybdate, and methylmercury by use of online microdialysis-packed minicolumn-inductively coupled plasma mass spectrometry Abstract: To study the permeability of the blood-brain barrier (BBB) to arsenates, arsenite, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), molybdate, and methylmercury, and the transfer behavior of these species, we constructed an automatic online analytical system comprising a microdialysis sampling device, a minicolumn packed with nonfunctionalized poly(vinyl chloride) beads, and an inductively coupled plasma mass spectrometer for continuous in-vivo measurement of their dynamic variation in the extracellular space of the brains of living rats. By using ion-polymer interactions as a novel working mechanism for sample pretreatment of volume-limited microdialysate, we simplified the operating procedure of conventional solid-phase extraction and reduced the contribution to the blank of the chemicals used. After optimizing this hyphenated system, we measured its performance by analysis of NIST standard reference materials 1640a (trace elements in natural water) and 2672a (trace elements in human urine) and by in-vivo monitoring of the dynamic variation of the compounds tested in the extracellular fluid (ECF) of rat brain. We found that intraperitoneal administration led to observable BBB permeability of arsenates, arsenite, DMA, MMA, and molybdate. Nevertheless, the limited sensitivity of the system and the size of microdialysis samples meant that detection of MeHg in ECF remained problematic, even when we administered a dose of 20 mg MeHg kg(-1) body weight. On the basis of these practical demonstrations, we suggest that our analytical system could be used not only for dynamic monitoring of the transfer kinetics of the four arsenicals and molybdate in the rat brain but also to describe associated neurotoxicity in terms of exposure to toxic metals and their species.",
Arsenic,67671,"Hematopoietic effects in mice exposed to arsine gas Abstract: Arsine gas is a potent hemolytic agent. Concern about semiconductor workers prompted an in-depth study of arsine at the National Institute of Environmental Health Sciences to determine the hematopoietic effects of prolonged exposure to this gas. Female B6C3F1 mice were exposed by inhalation to 0, 0.5, 2.5, and 5 ppm arsine, 6 hr/day for 14 days. Body weights of exposed mice were comparable to those of controls, but a marked, concentration-related splenomegaly was observed. Higher level arsine exposure produced statistically significant decreases in red blood cells, hematocrit and hemoglobin, with increases in white blood cell counts and mean corpuscular volume of red blood cells. Erythropoiesis as measured by quantitation of erythroid precursors in culture revealed a marrow reduction of colony-forming unit erythroids/femur cells for all treated groups on Day 3 postexposure and only at the 5 ppm dose group on 24 days postexposure, while splenic erythropoiesis increased at higher concentrations of arsine. There was no alteration in bone marrow cellularity and a less significant effect on granulocyte-macrophage progenitors. A 12-week study of arsine at 0, 0.025, 0.5, and 2.5 ppm (6 hr/day) by inhalation showed similar effects on hematopoiesis in mice. In conclusion, arsine exposure at low concentrations produces a stress on the hematopoietic system characterized by hemolysis, which persists for a prolonged period following exposure.",
Arsenic,1355662,DETECTION OF CYANIDE AND ARSENIC FROM ORAL-TISSUES OF ACUTE POISONED RABBITS Abstract: ,
Arsenic,1579313,"The impact of oscillating redox conditions: Arsenic immobilisation in contaminated calcareous floodplain soils Abstract: Arsenic contamination of floodplain soils is extensive and additional fresh arsenic inputs to the pedosphere from human activities are ongoing. We investigate the cumulative effects of repetitive soil redox cycles, which occur naturally during flooding and draining, on a calcareous fluvisol, the native microbial community and arsenic mobility following a simulated contamination event. We show through bioreactor experiments, spectroscopic techniques and modelling that repetitive redox cycling can decrease arsenic mobility during reducing conditions by up to 45%. Phylogenetic and functional analyses of the microbial community indicate that iron cycling is a key driver of observed changes to solution chemistry. We discuss probable mechanisms responsible for the arsenic immobilisation observed in-situ. The proposed mechanisms include, decreased heterotrophic iron reduction due to the depletion of labile particulate organic matter (POM), increases to the proportion of co-precipitated vs. aqueous or sorbed arsenic with ?-FeOOH/Fe(OH)3 and potential precipitation of amorphous ferric arsenate.",
Arsenic,1794827,"Occurrence of CCA-treated timber in caterers' fuelwood stocks in the Cape Town region Abstract: Wood used as fuel under conditions of urban poverty is a source of air pollution. Fuelwood is harvested from pen-urban green areas or sourced as waste from industry or commerce, and used in the informal economy, both by households and by productive activities such as roadside catering. End-of-life timber may have previously been treated for protection, sometimes by impregnation with chromated copper arsenate (CCA). Combustion of CCA-treated timber could magnify the health and environmental risks associated with air pollution, as a result of the release of arsenic and chromium in toxic and carcinogenic forms. Fuelwood supplies of roadside caterers in the urban settlements of Nyanga and Khayelitsha were randomly sampled and 86 collected specimens were prepared for analysis. A further 12 samples were taken, based on their appearance, from households and caterers in settlements near Stellenbosch, Worcester and Paarl. Shavings from the timber specimens were microwave digested using nitric acid and analysed using inductively coupled plasma analysis. All samples collected in the first round showed low concentrations of Cr, Cu and As, believed to be representative of natural backgrounds. Of the 12 pen-urban samples collected in the second round, 8 showed higher levels, typical of treatment to H2-H5 standards. Once it was clear that appearance was a fair indicator of treatment, a further set of 18 suspect pieces from caterers' supplies in Langa, Nyanga, Khayelitsha and Kayamandi were tested, of which at least 1 sample from each area was found to be treated. CCA-treated timber was found infrequently in fuel supplies of urban caterers, and more frequently in peri-urban areas. Further research and interventions to limit health and environmental risks are recommended.",
Arsenic,1003591,"A periplasmic arsenite-binding protein involved in regulating arsenite oxidation Abstract: Arsenic (As) is the most common toxic element in the environment, ranking first on the Superfund List of Hazardous Substances. Microbial redox transformations are the principal drivers of As chemical speciation, which in turn dictates As mobility and toxicity. Consequently, in order to manage or remediate environmental As, land managers need to understand how and why microorganisms react to As. Studies have demonstrated a two-component signal transduction system comprised of AioS (sensor kinase) and AioR (response regulator) is involved in regulating microbial AsIII oxidation, with the AsIII oxidase structural genes aioB and aioA being upregulated by AsIII. However, it is not known whether AsIII is first detected directly by AioS or by an intermediate. Herein we demonstrate the essential role of a periplasmic AsIII-binding protein encoded by aioX, which is upregulated by AsIII. An ?aioX mutant is defective for upregulation of the aioBA genes and consequently AsIII oxidation. Purified AioX expressed without its TAT-type signal peptide behaves as a monomer (MW 32?kDa), and Western blots show AioX to be exclusively associated with the cytoplasmic membrane. AioX binds AsIII with a K(D) of 2.4?µM AsIII; however, mutating a conserved Cys108 to either alanine or serine resulted in lack of AsIII binding, lack of aioBA induction, and correlated with a negative AsIII oxidation phenotype. The discovery and characterization of AioX illustrates a novel AsIII sensing mechanism that appears to be used in a range of bacteria and also provides one of the first examples of a bacterial signal anchor protein.",
Arsenic,2088489,"A Protective Role of Heme-Regulated eIF2? kinase in Cadmium-Induced Toxicity in Erythroid Cells Abstract: Although a number of studies have demonstrated that cadmium (Cd) can incur damage to mature red cells, the potential injuries of Cd to erythroid progenitor cells have not been investigated thus far. Heme-regulated eIF2? kinase (Hri) is essential for translational regulation and survival of erythroid precursors in the setting of iron deficiency. Hri has been demonstrated to activate Atf4 signaling in reducing oxidative stress and in promoting erythroid differentiation during stress erythropoiesis. Here, we demonstrated that Cd significantly provoked cell death and suppressed erythroid differentiation of erythroid progenitor cells. Importantly, our results established a crucial role of Hri in ameliorating Cd-induced impairment to erythropoiesis. Upon Cd treatment, Hri-eIF2?P-Atf4 signaling was activated to protect cells from cell death and differentiation attenuation in Wt fetal liver erythroblasts; in contrast, Hri(-/-) erythroblasts suffered from enhanced oxidative stress, as evidenced by increased levels of reactive oxygen species (ROS) and consequentially elevated apoptosis. As for Cd administration in vivo, impaired erythropoiesis in bone marrow and dramatic extramedullary erythropoiesis in spleen were observed in Hri(-/-) mice. Taken together, our combined data highlighted a crucial role of Hri in protecting survival and differentiation of erythroid progenitor cells upon Cd treatment.",
Arsenic,1027349,Relative susceptibility to arsenic in successive instars of the silkworm Abstract: The susceptibility of the silkworm to arsenic decreases during its larval development. Relative susceptibility may be expressed numerically as a ratio of areas under dosage-effect curves.,
Arsenic,2088515,"Urinary tuberculosis is associated with the development of urothelial carcinoma but not renal cell carcinoma: a nationwide cohort study in Taiwan Abstract: Background:Obstructive uropathy and chronic urinary tract infection increase the risk of urinary tract cancer. Urinary tuberculosis (UTB) can cause chronic urinary tract inflammation, lead to obstructive uropathy, and potentially contribute to the development of urinary tract cancer. However, the association between UTB and urinary tract cancer has not been studied.Methods:This study enrolled 135?142 tuberculosis (TB) cases (male, 69%) from a nationwide health insurance research database in Taiwan and investigated the risk factors for urinary tract cancer, with emphasis on a history of UTB. The incidence of urinary tract cancer in the general population without TB was also calculated for comparison.Results:The TB patients had a mean age of 57.5±19.5 years. Of the 1287 UTB and 133?855 non-UTB patients, 15 (1.2%) and 396 (0.3%) developed urothelial carcinoma, respectively (P&lt;0.001); and 2 (0.2%) and 96 (0.1%) developed renal cell carcinoma, respectively (P=0.240). Cox regression analysis revealed that age, male sex, end-stage renal disease, obstructive uropathy, arsenic intoxication, organ transplantation, and UTB (hazard ratio: 3.38 (2.01-5.69)) were independent risk factors for urothelial carcinoma. The hazard ratio of UTB was higher among female patients (5.26 (2.12-13.06)) than that among male patients (2.96 (1.57-5.60)).Conclusion:Urinary tuberculosis had a strong association with urothelial carcinoma, but not with renal cell carcinoma. In TB endemic areas, the urinary tract of TB patients should be scrutinised. It is also imperative that these patients be followed-up carefully in the post-treatment period, and urinalysis, ultrasonography or endoscopy should be an integral part of the follow-up.British Journal of Cancer advance online publication, 15 October 2013; doi:10.1038/bjc.2013.538 www.bjcancer.com.",
Arsenic,1519035,"Proteomic approach of adaptive response to arsenic stress in Exiguobacterium sp. S17, an extremophile strain isolated from a high-altitude Andean Lake stromatolite Abstract: The North-Western part of Argentina is particularly rich in wetlands located in the Puna in an altitude between 3,600 and 4,600 m above sea level. Most of these high-altitude Andean lakes are inhospitable areas due to extreme habitat conditions such as high contents of toxic elements, particularly arsenic. Exiguobacterium sp. S17, isolated from stromatolites in Laguna Socompa, exhibited remarkable tolerance to high arsenic concentration, i.e., it tolerated arsenic concentration such as 10 mM of As(III) and 150 mM of As(V). A proteomics approach was conducted to reveal the mechanisms that provide the observed outstanding resistance of Exiguobacterium sp. S17 against arsenic. A comparative analysis of S17, exposed and unexposed to arsenic revealed 25 differentially expressed proteins. Identification of these proteins was performed by MALDI-TOF/MS revealing upregulation of proteins involved in energy metabolism, stress, transport, and in protein synthesis being expressed under arsenic stress. To our knowledge, this work represents the first proteomic study of arsenic tolerance in an Exiguobacterium strain.",
Arsenic,1337530,"Molecular identification of an arsenic four-gene operon in Campylobacter lari Abstract: An arsenic (ars) four-gene operon, containing genes encoding a putative membrane permease (ArsP), a transcriptional repressor (ArsR), an arsenate reductase (ArsC) and an arsenical-resistance membrane transporter (Acr3) was first identified in urease-positive thermophilic Campylobacter (UPTC) isolate, CF89-12. UPTC CF89-12 and some other Campylobacter lari isolates contained their ars four-genes, similarly, differing from that in the reference C. lari RM2100 strain. Two putative promoters and a putative terminator were identified for the operon in UPTC CF89-12. In vivo transcription of the operon was confirmed in the UPTC cells. PCR experiments using two primer pairs designed in silico to amplify two arsR and arsC-acr3 segments, respectively, generated two amplicons, approximately 200 and 350 base pairs, with all 31 of 31 and 19 of 31 C. lari isolates (n?=?17 for UPTC; n?=?14 for UN C. lari), respectively. An inverted repeat forming a dyad structure, a potential binding site for a transcriptional repressor, was identified in the promoter region. Within the deduced 61 amino acids sequence of the putative arsR open reading frame from the UPTC CF89-12, a metal binding box and a DNA-binding helix-turn-helix motif were identified. The UPTC CF89-12 and some other UPTC isolates isolated from natural environment were resistant to arsenate.",
Arsenic,2337123,"SYNTHESIS OF MAGNETIC AS(V)-IMPRINTED POLYMERS AND THEIR ADSORPTION PERFORMANCES FOR ARSENATE IN WATER SOLUTIONS Abstract: Three magnetic As(V)-imprinted polymers have been synthesized by surface-ion-imprinted technology with Fe3O4 nanoparticles as the support. The adsorption performances for arsenate in aqueous solutions using these polymers were investigated. The results showed that the difference of solvents and crosslinkers used in the experiments significantly affected the adsorption efficiency of the synthesized materials. It was found that the magnetic As(V)-imprinted polymer synthesized with ethanol as the solvent and without a crosslinker (IIP-eth) was most efficient for arsenate removal. The surface morphology and structure of this IIP-eth adsorbent was characterized by FT-IR, SEM, TEM and BET-N-2 adsorption technology. The results revealed that the IIP-eth was mainly consists of nanoparticles about 10nm with micropores. Its maximum adsorption capacity was 3.24mg/g at pH 4-5. The adsorption equilibrium can be reached within 10min and the adsorbent easily separated by applying an external magnetic field. The imprinting effect and the template-recognition behaviors of the As(V)-imprinted polymer was reflected by the selective adsorption for arsenate in the presence of other competing ions including Zn(II), Cd(II), Mn(II) and P(V). The desorption of arsenate was easy and the desorption rate was almost 100% when 2 mol/L HCl was used as the eluent. It can be concluded that the synthesized IIP-eth is a promising absorbent for the selective removal of arsenic from water solutions.",
Arsenic,2225297,"Potential of Novel Bacterial Consortium for the Remediation of Chromium Contamination Abstract: This study was aimed to examine the efficiency of a novel bacterial consortium on the reduction of toxic hexavalent chromium [Cr(VI)] to non-toxic trivalent Cr [Cr(III)]. Six Cr(VI)-resistant bacteria (IS1-IS6) were isolated from a tannery waste disposal site at Mount Barker, South Australia, of which three viz., IS1, IS2 and IS3 were selected based on Cr(VI) reduction ability in minimal salt medium. The isolates were identified as Bacillus endophyticus (IS1), Microbacterium paraoxydans (IS2) and Bacillus simplex (IS3) by 16S rRNA gene sequencing. All three isolates were able to tolerate chromium (Cr(VI), 300-400 mg L-1), arsenic (As(V), 1,000 mg L-1), copper (Cu(II), 300-400 mg L-1) and lead (Pb(II), 1,000 mg L-1). The isolates were evaluated both as an individual and as a consortia for Cr(VI) reduction inminimal salt medium and storm water, both spiked with 100 mg Cr(VI) L-1. In both cases, the rate of Cr(VI) reduction was found to be significantly higher in the bacterial consortium inoculation (t(1/2) = 8.45 for minimal salt medium; 6.02 h for storm water), compared to inoculation with individual isolates (t = 53.3-115.5 h for minimal salt medium; 8.77-9.76 h for storm water). The rate of Cr(VI) reduction in both minimal salt medium and storm water was found to be higher in bacterial consortium inoculation (IS1+IS2+IS3) than in individual isolate inoculation. This experiment demonstrated that bacterial consortium prepared by using B. endophyticus, M. paraoxydans and B. simplex was more effective in Cr(VI) detoxification than application of individual bacterium. This experiment also proved that a bacterial consortium was more effective in Cr(VI) detoxification than the application of individual bacterial strain.",
Arsenic,2345838,"Effect of sample preparation procedure for the determination of As, Sb and Se in fruit juices by HG-ICP-OES Abstract: Various sample preparation procedures for the simultaneous determination of As, Sb and Se in fruit juices by hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP-OES) were examined. Applicability of total wet digestion with HNO3/H2O2, partial decomposition (solubilisation in aqua regia), 1:1 dilution with 2% (v/v) HNO3 and direct analysis were evaluated. Hydrides were generated in the reaction of an acidified sample with NaBH4 after pre-reduction with KI-ascorbic acid for total As and Sb, and boiling with HCl for total Se. Best results, i.e. limits of detection (LODs) of 0.51-0.73 ng mL(-1), precision (RSD) within 1.7-3.6% and recoveries for spiked samples between 101% and 106% were found using aqua regia treatment. This procedure simplifying and improving sample preparation step prior to As, Sb and Se measurements in fruit juices by HG-ICP-OES, thus could be adequate for the routine analysis in terms of the quality control of these drinks. (C) 2014 Elsevier Ltd. All rights reserved.",
Arsenic,1032050,"The detection and estimation of (A) arsenic in opium, and (B) strychnine in opium and heroin, as a means of identification of their respective sources Abstract: Samples of opium with arsenic as an adulterant, and both opium and heroin with strychnine as an adulterant are not infrequently encountered in the local drug scene. The paper describes a method for the possible identification of the sources of opium and heroin in the local market on the basis of an accurate quantitation of the adulterant arsenic and strychnine contents of the respective samples. A possible extension of this concept, would be the possibility of a similar identification of sources outside the country with a view to establishing channels of entry from abroad. Arsenic is determined by the Gutzeit method while strychnine is estimated by high performance liquid chromatography (HPLC).",
Arsenic,1351331,"Mineral Contents and Heavy Metal Contamination in Kashar Cheeses Consumed in Erzurum Province, Turkey Abstract: ",
Arsenic,628777,"Protective effect of N-acetylcysteine against arsenic-induced depletion in vivo of carbohydrate Abstract: N-acetylcysteine (NAC), a synthetic aminothiol, possesses antioxidative and cytoprotective properties. The present study evaluates the effect of NAC supplementation on arsenic-induced depletion in vivo of carbohydrates. Arsenic (as sodium arsenite) treatment (i.p.) of male Wistar rats (120-140 g b.w.) at a dose of 5.55 mg/kg body weight (35% of LD50) per day for a period of 30 days produced a significant decrease in blood glucose level (hypoglycemia) and a fall in liver glycogen and pyruvic acid contents. The free amino acid nitrogen content of liver increased while that of kidney decreased after arsenic treatment. Arsenic also enhanced the liver lactate dehydrogenase activity whereas glucose 6-phosphatase activity in both liver and kidney decreased significantly following arsenic treatment. Transaminase activities in liver and kidney were not significantly altered except the glutamate-pyruvate transaminase activity that was reduced in kidney after arsenic treatment. Oral administration of NAC (163.2 mg/kg/day) for last 7 days of treatment prevented the arsenic-induced hypoglycemia and glycogenolytic effects to an appreciable extent. There was also recovery of liver pyruvic acid as well as liver and kidney free amino acid nitrogen content after NAC supplementation. Arsenic-induced alteration of glucose 6-phosphatase activity in both liver and kidney was also counteracted by NAC. It is suggested that carbohydrate depletion in vivo due to exposure to arsenic can be counteracted by NAC supplementation.",
Arsenic,1498020,"Simultaneously evaluate the toxic levels of fluoride and arsenic species in underground water of Tharparkar and possible contaminant sources: A multivariate study Abstract: The present study investigated total arsenic (tAs), inorganic arsenic (iAs) species and fluoride ion (F(-)) contamination in underground water of Mithi and Nangarparkar subdistricts of Tharparkar, Pakistan. Statistical parameters, principal component analysis, cluster analysis, sodium absorption ratio and saturation indices (SI) were used to detect interrelation and sources of concentration of tAs, iAs species (As(3+) and As(5+)), F(-) and others physicochemical parameters. The concentration of As(3+) was measured by cloud point extraction using ammonium pyrrolidinedithiocarbamate (APDC) as complexing reagent, while inorganic arsenic (iAs) was determined by solid phase extraction, using titanium dioxide. The positive correlation was observed between F(-) contents with As species and other major ions, found in the underground water of the study area. The resulted data indicated that underground water samples of two areas of Tharparkar were severely contaminated with arsenic (0.100-3.83mg/L) and fluoride ion (13.8-49.3mg/L), which were exceeded the World Health Organization provisional guideline values, 0.01mg/L and 1.5mg/L, respectively. The SI of fluorite and calcite in the underground water samples showed that most of the samples were oversaturated with respect to calcite and fluorite.",
Arsenic,1579262,"Measuring the applicability of biosensors to detect possible terror chemicals in water distribution network Abstract: Instant and accurate detection of chemical contamination in a water distribution system is significant in protecting public health and water resource. Using water quality surrogates to signal a contamination occurrence offers the advantage of detecting a large number of chemicals. This article describes how the indigenous biofilm in a contaminated drinking water system may provide an effective indirect surrogate response with either turbidity or ultraviolet changes (UV254). Rotating annular bioreactors (RAB) and pipe loops were used to quantify biofilm along with turbidity and UV254 measurements. The number of biofilm cells on the polyvinyl chloride (PVC) analytical coupons was also enumerated, using automated fluorescence microscopy. Measuring the biosensing capacity, the analytical coupons were submersed into beakers with potential chemical contaminants such as aldicarb, cyanide, cycloheximide, nicotine, sodium arsenate, and sodium fluoroacetate. Resulting data indicated that turbidity was a useful surrogate for forensically monitoring chemical contaminants. Turbidity measurement can make an inexpensive biosensor for the security of a water distribution system.",
Arsenic,2064279,"Functional characterization of SbmA, a bacterial inner membrane transporter required for importing the antimicrobial peptide Bac7(1-35) Abstract: SbmA is an inner membrane protein of Gram-negative bacteria that is involved in the internalisation of glycopeptides, of prokaryotic and eukaryotic antimicrobial peptides, as well as of peptide-nucleic acid (PNA) oligomers. The SbmA homolog BacA is required for the development of Sinorhizobium meliloti bacteroids within plant cells and favours chronic infections with Brucella abortus and Mycobacterium tuberculosis in mice. Here, we investigated functional features of SbmA/BacA using the proline-rich antimicrobial peptide Bac7(1-35) as a substrate. Circular dichroism and affinity chromatography studies were used to investigate the ability of SbmA to bind the peptide, and a whole cell transport assay with fluorescently-labelled peptide allowed the determination of transport kinetic parameters with a calculated Km value of 6.95±0.89 ?M peptide and a Vmax of 53.91±3.17 nmol/min/mg SbmA. Use of a bacterial two-hybrid system coupled to SEC-MALLS analyses established that SbmA is a homodimer in the membrane, and treatment of the cells with arsenate or ionophores indicate that the peptide transport mediated by SbmA is driven by the electrochemical gradient. Overall these results shed light on the SbmA-mediated internalisation of peptide substrates and suggest that the transport of (an) unknown substrate(s) represent the function of this protein.",
Arsenic,1508593,"Novel phytase from Pteris vittata resistant to arsenate, high temperature, and soil deactivation Abstract: Arsenate interferes with enzymatic processes and inhibits inorganic phosphorus (P(i)) uptake in many plants. This study examined the role of phytase and phosphatase in arsenate tolerance and phosphorus (P) acquisition in the arsenic hyperaccumulator Pteris vittata . Enzyme-mediated hydrolysis of phytate in P. vittata extracts was not inhibited by arsenate at 5 mM or by heating at 100 °C for 10 min. Root exudates of P. vittata exhibited the highest phytase activity (18 nmol P(i) mg(-1) protein min(-1)) when available P was low, allowing its growth on media amended with phytate as the sole source of P. Phosphorus concentration in P. vittata gametophyte tissue grown on phytate was equivalent to plants grown with inorganic phosphate at 2208 mg kg(-1), and arsenic was increased from 1777 to 2630 mg kg(-1). After 2 h of mixing with three soils, P. vittata phytase retained more activity, decreasing from ?26 to ?25 nmol P(i) mg(-1) protein min(-1), whereas those from Pteris ensiformis and wheat decreased from ?18 to ?1 nmol P(i) mg(-1) protein min(-1). These results suggest P. vittata has a uniquely stable phytase enabling its P acquisition in P-limiting soil environments. Furthermore, the P. vittata phytase has potential use as a soil amendment, a transgenic tool, or as a feed additive supplement, reducing the need for nonrenewable, polluting P fertilizers.",
Arsenic,1343730,NMR spectral studies X - Arsenic trichloride as a convenient solvent for C-13 NMR spectroscopy Abstract: ,
Arsenic,1579298,"Single dose pharmacokinetics of oral tenofovir in plasma, peripheral blood mononuclear cells, colonic and vaginal tissue Abstract: HIV seroconversion outcomes in pre-exposure prophylaxis (PrEP) trials of oral tenofovir (TFV)-containing regimens are sensitive to drug concentration, yet less-than-daily dosing regimens are studied. Description of TFV and TFV diphosphate (TFV-DP), in blood, vaginal tissue, and colon tissue may guide the design and interpretation of PrEP clinical trials. Six healthy women were administered a single oral dose of 300 mg tenofovir disoproxil fumarate (TDF) and 4.3 mg (12.31 MBq, 333 ?Ci) 14C-TDF. Blood was collected every 4 h for the first 24 h, then at 4, 8, 11, and 15 days post-dosing. Colonic and vaginal samples were collected 1, 8 and 15 days post-dose. Samples were analyzed for TFV and TFV-DP. Plasma TFV demonstrated triphasic decay with terminal elimination half-life median (interquartile range [IQR]) 69 hour (58 - 77). PBMC TFV-DP demonstrated biphasic peaks (median 12 h and 96 h) followed by a terminal 48 hour (38 - 76) half-life; Cmax was 20 fmol/million cells (20 - 63). One day post-dose, the TFV-DP paired colon:vaginal tissue concentration ratio was 1 or greater in all subjects' tissue homogenates, median 124 (range 1-281), but was not sustained. The ratio was lower and more variable in cells extracted from tissue. Among all sample types, TFV and TFV-DP half-life ranged from 23 - 139 hours. PBMC TFV-DP rose slowly in the hours after dosing indicating success with exposure-driven dosing regimens may be sensitive to timing of the dose prior to exposure. Colonic tissue homogenate TFV-DP concentrations were greater than in vaginal homogenate at 24 hours, but not in cells extracted from tissue. These and the other pharmacokinetic findings will guide interpretation and design of future PrEP trials.",
Arsenic,1016037,"Selenium effects on arsenic cytotoxicity and protein phosphorylation in human kidney cells using chip-based nanoLC-MS/MS Abstract: Although arsenic toxicity is well known, little is known of how it exerts its effects at the proteome level. Protein phosphorylation is an important post-translational modification in the regulation of cell signaling. Despite the importance of protein phosphorylation, the identification and characterization of phosphorylated proteins, as influenced by interaction between arsenic and selenium species have not been fully studied. The aim of this study is to identify phosphorylation in arsenic toxified cells, with and without selenium present. Here, we identify the phosphorylated proteins related to post translational modifications (PTMs) after inorganic arsenic (iAs) and selenomethionine (SeMet) were inoculated together with HEK293 human kidney cells. In this study, using TiO(2)-based nanoLC-phosphochip® coupled to ESI-MS we observed phosphorylated peptide enrichment and significant reduction in sample complexity. The identification of phosphorylated proteins in highly complex digests of cell lysate were markedly different with As toxification only, or when in the presence of SeMet. Several phosphorylation sites and proteins are identified using Spectrum Mill and Mascot protein data base search engines. Cytotoxicity studies showed that SeMet significantly reduces the cytotoxic effect of iAs in HEK293 cells, while inorganic selenium did not.",
Arsenic,8792,"Quantitative studies of in vitro morphological transformation of Syrian hamster cells by inorganic metal salts Abstract: Morphological transformation of Syrian hamster embryo cells was induced by direct exposure to some inorganic salts of nickel, cadmium, chromium, beryllium, and arsenic but not salts of iron, titanium, tungstate, zinc, aluminum, and nickel sulfide amorphous. Furthermore, no transformation was observed in untreated controls. Lethality, indicated by a reduction in cloning efficiency, occurred with carcinogenic and noncarcinogenic metal salts. In addition, transformation of Syrian hamster cells was observed also after transplacental exposure to inorganic salts of nickel, beryllium, chromate, and cadmium which had been injected into pregnant hamsters. The transformed colonies had a variety of morphologies reflecting the cell types present in early passages of cells and were identical to those observed after organic carcinogens. Animal experimental data exist for the carcinogenicity of all positive inorganic metals except arsenic. Epidemiological evidence indicates an association between exposures to all positive metals except for cadmium, although there is a possibility of a relationship between occupational exposure to cadmium and cancer of the prostate. Although in terms of dose-response relationships cadmium and chromium were the most potent transforming agents, the comparative potency of the various metals cannot be determined since it would depend on the ionization potential of the metal, the inorganic salt form, and possible biointeractions of the various metals.",
Arsenic,1597428,"Detection of trace copper metal at carbon nanotube based electrodes using squarewave anodic stripping voltammetry Abstract: We investigate sensitivity and limit of detection (LOD) of trace copper (Cu) metal using pristine carbon nanotube (CNT) and acidified CNT (ACNT) electrodes. Squarewave based anodic stripping voltammetry (SWASV) is used to determine the stripped Cu concentration. Prior to performing the SWASV measurements, its optimal conditions are determined and with that, effects of potential scan rate and concentration on stripping current are evaluated. The measurements indicate that (1) ACNT electrode shows better results than CNT electrode and (2) stripping is controlled by surface reaction. In the given concentration range of 25-150 ppb, peak stripping current has linearity with concentration. Quantitatively, sensitivity and LOD of Cu in ACNT electrode are 9.36 and 3 ppb, while their values are 3.99 and 3 ppb with CNT electrode. We evaluate the effect of three different water solutions (deionized water, tap water and river water) on stripping current and the confirm types of water don't affect the sensitivity of Cu. It turns out by optical inspection and cyclic voltammetry that superiority of ACNT electrode to CNT electrode is attributed to exfoliation of CNT bundles and improved interfacial adhesion occurring during oxidation of CNTs.",
Arsenic,2278852,"Contaminant levels in Gulf of Mexico reef fish after the Deepwater Horizon oil spill as measured by a fishermen-led testing program Abstract: The BP oil disaster posed a significant threat to the U.S. seafood industry. Invertebrates (shrimp, oyster, crab) and other nearshore species comprised the majority of postspill testing by federal and state agencies. Deeper water finfish were sampled less frequently, despite population ranges that overlapped with affected waters. We report on a voluntary testing program with Gulf of Mexico commercial fishermen to ensure the safety of their catch. Seven species of reef fish were tested for polycyclic aromatic hydrocarbons, several metals, and a constituent of Corexit 9500A and 9527A dispersants. Only two of 92 samples had detectable levels of benzo(a)pyrene-equivalents (a combined measure of carcinogenic potency across 7 different PAHs), which were still below federal safety thresholds. PAH ratios for these samples suggest pyrogenic (not petrogenic) contamination - indicating potential sources other than Deepwater Horizon. Metals were largely absent (cadmium, lead) or consistent with levels previously reported (mercury, arsenic). One notable exception was tilefish, which showed mercury concentrations lower than expected. We did not detect dispersant in any of our samples, indicating that it was not present in these species during the study period. Our findings suggest minimal risk to public health from these seafoods as a result of the disaster; however, the most contaminated areas were not sampled through this program.",
Arsenic,1025442,"Inorganic arsenic induces necrosis of human CD34-positive haematopoietic stem cells Abstract: Inorganic arsenic is a major environmental contaminant known to exert immunosuppressive effects. In this study, we report toxicity of As2O3, a trivalent inorganic form, toward isolated human hematopoietic CD34+ progenitor cells. Our results demonstrate that low concentrations of As2O3 (0.1-5 microM) inhibit in vitro proliferation of CD34+ cells and their differentiation into various hematological cell lineages. These effects were associated with the induction of a necrotic process independent of caspases and likely related to mitochondrial damage. We conclude that As2O3 can impair in vitro human hematopoiesis by decreasing survival of CD34+ progenitor cells.",
Arsenic,2343507,"Effect of aging on arsenic and lead fractionation and availability in soils: Coupling sequential extractions with diffusive gradients in thin-films technique Abstract: We coupled the diffusive gradients in thin-films (DGT) technique with two sequential extraction methods to investigate the influence of aging on As and Pb fractionation and availability in three soils spiked with As (40 or 400mgkg(-1)), Pb (150 or 1500mgkg(-1)) or As+Pb (40mgkg(-1) As and 150mgkg(-1) Pb). During aging, As moved from the more available (non-specifically and specifically sorbed) to less available (amorphous and crystallized Fe/Al) fractions while Pb moved from the first three fractions (exchangeable, carbonate and Fe/Mn hydroxide) to organic fraction. However, even after 33-week aging, much more As and Pb were in the least available residual fraction in spiked soils than native soils (11-59% vs. 1.2-12%). Relatively, As in spiked soils was much more available than Pb with 11-14% As and 46-59% Pb in the residual fraction. Correlation analysis indicated that As in the non-specifically and specifically sorbed fractions and Pb in the exchangeable fraction were likely sources of DGT-measured labile As and Pb. The fact that As and Pb distribution and availability in spiked soils were significantly different from native soils suggests caution needs to be exercised when using spiked soils for research.",
Arsenic,1026273,"Comparison of arsenic content in pelletized poultry house waste and biosolids fertilizer Abstract: Managers of human biosolids have been incorporating the practice of waste pelletization for use as fertilizer since the mid 1920s, and waste pelletization has recently been embraced by some poultry producers as a way to move nutrients away from saturated agricultural land. However, the presence of arsenic in pelletized poultry house waste (PPHW) resulting from the use of organoarsenical antimicrobial drugs in poultry production raises concerns regarding additional incremental population exposures. Arsenic concentrations were determined in PPHW and pelletized biosolids fertilizer (PBF) samples. Pellets were processed using strong acid microwave digestion and analyzed by graphite furnace atomic absorption spectroscopy. The mean arsenic concentration in PPHW (20.1 ppm) fell within the lower part of the range of previously report arsenic concentrations in unpelletized poultry house waste. Arsenic concentrations in PBF, the source of which is less clear than for PPHW, were approximately a factor of 5 times lower than those in PPHW, with a mean concentration of 4.1 ppm. The pelletization and sale of these biological waste fertilizers present new pathways of exposure to arsenic in consumer populations who would otherwise not come into contact with these wastes. Arsenic exposures in humans resulting from use of these fertilizer pellets should be quantified to avoid potential unintended negative consequences of managing wastes through pelletization.",
Arsenic,1029247,"Trivalent dimethylarsenic compound induces histone H3 phosphorylation and abnormal localization of Aurora B kinase in HepG2 cells Abstract: Trivalent dimethylarsinous acid [DMA(III)] has been shown to induce mitotic abnormalities, such as centrosome abnormality, multipolar spindles, multipolar division, and aneuploidy, in several cell lines. In order to elucidate the mechanisms underlying these mitotic abnormalities, we investigated DMA(III)-mediated changes in histone H3 phosphorylation and localization of Aurora B kinase, which is a key molecule in cell mitosis. DMA(III) caused the phosphorylation of histone H3 (ser10) and was distributed predominantly in mitotic cells, especially in prometaphase cells. By contrast, most of the phospho-histone H3 was found to be localized in interphase cells after treatment with inorganic arsenite [iAs(III)], suggesting the involvement of a different pathway in phosphorylation. DMA(III) activated Aurora B kinase and slightly activated ERK MAP kinase. Phosphorylation of histone H3 by DMA(III) was effectively reduced by ZM447439 (Aurora kinase inhibitor) and slightly reduced by U0126 (MEK inhibitor). By contrast, iAs(III)-dependent histone H3 phosphorylation was markedly reduced by U0126. Aurora B kinase is generally localized in the midbody during telophase and plays an important role in cytokinesis. However, in some cells treated with DMA(III), Aurora B was not localized in the midbody of telophase cells. These findings suggested that DMA(III) induced a spindle abnormality, thereby activating the spindle assembly checkpoint (SAC) through the Aurora B kinase pathway. In addition, cytokinesis was not completed because of the abnormal localization of Aurora B kinase by DMA(III), thereby resulting in the generation of multinucleated cells. These results provide insight into the mechanism of arsenic tumorigenesis.",
Arsenic,1027674,Studies in the incidence of cancer in a factory handling inorganic compounds of arsenic; mortality experience in the factory Abstract: ,
Arsenic,1337569,"Unusual localization of a common cutaneous neoplasm: basal cell carcinoma Abstract: Basal cell carcinoma (BCC) is the most common form of the skin carcinomas and ultraviolet radiation is the major risk factor in the etiopathogenesis. However, reports of unusual sites for BCC are increased in the literature. Authors draw attention to possibility of other etiological agents for BCC like local trauma, ageing, ionizing radiation, arsenic, chronic inflammation, and immune deficiency. Here, we reported a 74-year-old male patient with nodular BCC on groin. We thought that ageing or local trauma may have a role in its formation.",
Arsenic,1704148,"Changes in bacterial community structure and abundance in agricultural soils under varying levels of arsenic contamination Abstract: Arsenic contamination from groundwater used to irrigate crops is a major issue across several agriculturally important areas of Asia. Assessing bacterial community composition in highly contaminated sites could lead to the identification of novel bioremediation strategies. In this study, the bacterial community structure and abundance are assessed in agricultural soils with varying levels of arsenic contamination at Ambagarh Chauki block, Chhattisgarh, India, based on polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of the 16S rRNA gene and the most probable number-polymerase chain reaction (MPN-PCR). The results revealed that the bacterial communities of arsenic-contaminated soils are dominated by ?-proteobacteria (36%), ?-proteobacteria (21%), ?-proteobacteria (11%), ?-proteobacteria (11%), and Bacteroidetes (11%). The bacterial composition of high arsenic-contaminated soils differed significantly from that of low arsenic-contaminated soils. The Proteobacteria appeared to be more resistant to arsenic contamination, while the Bacteroidetes and Nitrospirae were more sensitive to it. The bacterial abundance determined by MPN-PCR decreased significantly as As-toxicity increased. In addition to As, other trace metals, like Pb, U, Cu, Ni, Sn, Zn and Zr, significantly ( p < 0.01) explain the changes in bacterial structural diversity in agricultural soils with different level of arsenic contamination, as determined by canonical correspondence analysis (CCA).",
Arsenic,2298732,"Effects of seasonal operation on the quality of water produced by public-supply wells Abstract: Seasonal variability in groundwater pumping is common in many places, but resulting effects of seasonal pumping stress on the quality of water produced by public-supply wells are not thoroughly understood. Analysis of historical water-quality samples from public-supply wells completed in deep basin-fill aquifers in Modesto, California (134 wells) and Albuquerque, New Mexico (95 wells) indicates that several wells have seasonal variability in concentrations of contaminants of concern. In Modesto, supply wells are more likely to produce younger groundwater with higher nitrate and uranium concentrations during the summer (high) pumping season than during the winter (low) pumping season. In Albuquerque, supply wells are more likely to produce older groundwater with higher arsenic concentrations during the winter pumping season than during the summer pumping season. Seasonal variability in contaminant concentrations in Modesto is influenced primarily by effects of summer pumping on vertical hydraulic gradients that drive migration of shallow groundwater through the aquifer to supply wells. Variability in Albuquerque is influenced primarily by the period of time that a supply well is idle, allowing its wellbore to act as a conduit for vertical groundwater flow and contaminant migration. However, both processes are observed in each study area. Similar findings would appear to be likely in other alluvial basins with stratified water quality and substantial vertical head gradients. Results suggest that even in aquifers dominated by old groundwater, changes to seasonal pumping patterns and/or to depth of well completion can help reduce vulnerability to selected contaminants of either natural or anthropogenic origin.",
Arsenic,1017573,"Inhibition of arsenic-induced rat liver injury by grape seed exact through suppression of NADPH oxidase and TGF-?/Smad activation Abstract: Chronic arsenic exposure induces oxidative damage to liver leading to liver fibrosis. We aimed to define the effect of grape seed extract (GSE), an antioxidant dietary supplement, on arsenic-induced liver injury. First, Male Sprague-Dawley rats were exposed to a low level of arsenic in drinking water (30ppm) with or without GSE (100mg/kg, every other day by oral gavage) for 12months and the effect of GSE on arsenic-induced hepatotoxicity was examined. The results from this study revealed that GSE co-treatment significantly attenuated arsenic-induced low antioxidant defense, oxidative damage, proinflammatory cytokines and fibrogenic genes. Moreover, GSE reduced arsenic-stimulated Smad2/3 phosphorylation and protein levels of NADPH oxidase subunits (Nox2, Nox4 and p47phox). Next, we explored the molecular mechanisms underlying GSE inhibition of arsenic toxicity using cultured rat hepatic stellate cells (HSCs). From the in vitro study, we found that GSE dose-dependently reduced arsenic-stimulated ROS production and NADPH oxidase activities. Both NADPH oxidases flavoprotein inhibitor DPI and Nox4 siRNA blocked arsenic-induced ROS production, whereas Nox4 overexpression suppressed the inhibitory effects of GSE on arsenic-induced ROS production and NADPH oxidase activities, as well as expression of TGF-?1, type I procollagen (Coll-I) and ?-smooth muscle actin (?-SMA) mRNA. We also observed that GSE dose-dependently inhibited TGF-?1-induced transactivation of the TGF-?-induced smad response element p3TP-Lux, and that forced expression of Smad3 attenuated the inhibitory effects of GSE on TGF-?1-induced mRNA expression of Coll-I and ?-SMA. Collectively, GSE could be a potential dietary therapeutic agent for arsenic-induced liver injury through suppression of NADPH oxidase and TGF-?/Smad activation.",
Arsenic,1020640,"Effect of phosphate transporter and methylation inhibitor drugs on the disposition of arsenate and arsenite in rats Abstract: Arsenate (AsV) is biotransformed into the more toxic arsenite (AsIII) and monomethylarsonous acid (MMAsIII), but it is unknown how to decrease production of these harmful metabolites. We investigated the effects of foscarnet and fosfomycin, drugs interacting with the phosphate transporter, on biotransformation of AsV, an analog of inorganic phosphate. The effects of entacapone, an inhibitor of catechol-O-methyl transferase (COMT), and nitrous oxide, an inactivator of methylcobalamin, were also tested on the formation of MMAsIII from AsIII in order to clarify the role of COMT and methylcobalamin in biomethylation of AsIII. Arsenic in bile and urine of control and treated rats receiving AsV or AsIII was speciated by HPLC-HG-AFS. In AsV-injected rats, foscarnet, but not fosfomycin, increased the urinary excretion of AsV and decreased the biliary and urinary excretion of AsIII as well as biliary excretion of MMAsIII. In AsIII-injected rats, however, foscarnet failed to influence the excretion of AsIII and its metabolites, suggesting that this drug inhibits the hepatic uptake and renal reabsorption of AsV, thereby decreasing formation of AsIII and MMAsIII from AsV. Entacapone or nitrous oxide pretreatment slightly or not at all influenced the biliary excretion of MMAsIII and urinary excretion of dimethylarsinic acid (DMAsV) in AsIII-injected rats. In contrast, periodate-oxidized adenosine, an inhibitor of S-adenosylmethionine-dependent methyltransferases, nearly abolished appearance of methylated arsenic metabolites in bile and urine. Thus, foscarnet facilitates urinary clearance of AsV and decreases formation of toxic AsIII and MMAsIII, indicating that this drug may be used to promote elimination and counter toxification of AsV. Because entacapone and nitrous oxide influenced the excretion of MMAsIII and DMAsV negligibly, neither COMT nor methylcobalamin appears to be involved in arsenic methylation in rats.",
Arsenic,1519235,"Vertical Distribution and Mobilization of Arsenic in Shallow Alluvial Aquifers of Chapai-Nawabganj District, Northwestern Bangladesh Abstract: ",
Arsenic,2337082,"The effect of silicon on the uptake and translocation of arsenic in tomato (Solanum lycopersicum L.) Abstract: Measuring tomato seed germination on a medium containing either arsenite or arsenate showed that the presence of 0.5 mM NaH2AsO4 center dot 7H(2)O reduced germination by between 20% and 40%, depending on cultivar. The inhibitory effect was mitigated by the addition of CaSiO3. However, the presence of both forms of As had a drastic negative effect on seedling shoot elongation, which was not mitigated by the presence of CaSiO3. In a subsequent soil-based pot trial, damage due to the presence of As was visible by 15 days after the initiation of the treatment, and the provision of CaSiO3 was significantly ameliorative; again, the severity of the effects was cultivar-dependent. Analysis of the accumulation and distribution of As showed that some of the cultivars are As excluders, and others accumulators. As was taken up by the latter cultivars whether or not CaSiO3 supplementation was provided. The extent of As entry into the fruit varied from cultivar to cultivar, but never rose above the safety threshold. A survey of stress response-associated genes showed that LeGR was strongly up-regulated by exposure to As. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,628493,"Thio-dimethylarsinate is a common metabolite in urine samples from arsenic-exposed women in Bangladesh Abstract: Over the last 6 years, much work on arsenic species in urine samples has been directed toward the determination of the reduced dimethylated arsenic species, DMA(III), because of its high toxicity and perceived key role in the metabolism of inorganic arsenic. Recent work, however, has suggested that DMA(III) may at times have been misidentified because its chromatographic properties can be similar to those of thio-dimethylarsinate (thio-DMA). We analyzed by HPLC-ICPMS (inductively coupled plasma mass spectrometry) urine samples from 75 arsenic-exposed women from Bangladesh with total arsenic concentrations ranging from 8 to 1034 microg As/L and found that thio-DMA was present in 44% of the samples at concentrations ranging mostly from trace amounts to 24 microg As/L (one sample contained 123 microg As/L). Cytotoxicity testing with HepG2 cells derived from human hepatocarcinoma indicated that thio-DMA was about 10-fold more cytotoxic than dimethylarsinate (DMA). The widespread occurrence of thio-DMA in urine from these arsenic-exposed women suggests that this arsenical may also be present in other urine samples and has so far escaped detection. The work highlights the need for analytical methods providing specific determinations of arsenic compounds in future studies on arsenic metabolism and toxicology.",
Arsenic,1644871,"Immunomodulatory effects of nanocurcumin in arsenic-exposed rats Abstract: We evaluated whether the nanoformulation of curcumin could be more effective than free curcumin against arsenic-induced immune dysfunction in rats. Curcumin was encapsulated in polylactic-co-glycolic acid (PLGA). Nanocurcumin (CUR-NP) exhibited a spherical shape with the mean particle size of 130.8nm. Rats were randomly divided into five groups of six each. Group I was kept as the control. In Group II, rats were exposed to sodium arsenite (25ppm) daily through drinking water for 42days. Groups III, IV and V were treated with arsenic as in Group II, however, they were administered with nanoparticle, curcumin (100mg/kgbw) and CUR-NP (100mg/kgbw), respectively, by oral gavage during the last 14days of arsenic exposure. At term, serum and spleen were collected. Immune dysfunction was evaluated by assessing cellular and humoral immunities. Arsenic significantly decreased the splenic lymphocyte proliferation in response to the antigen - Keyhole Limpet Hemocyanin (KLH) and mitogen - concanavalin-A. Arsenic reduced both the delayed type hypersensitivity response and secondary antibody (IgG) response to KLH. It also reduced the lipopolysaccharide-stimulated nitric oxide production in splenic lymphocytes. Free curcumin and CUR-NP treatment significantly attenuated these arsenic-mediated effects. However, the magnitude of the effects indicates that CUR-NP has better ameliorative potential than free curcumin at the equivalent dose level.",
Arsenic,732024,"Pharmacologic inhibitors of PI3K/Akt potentiate the apoptotic action of the antileukemic drug arsenic trioxide via glutathione depletion and increased peroxide accumulation in myeloid leukemia cells Abstract: Treatment for 14 to 24 hours with low concentrations of arsenic trioxide (As2O3, 1-4 microM) caused apoptosis in U-937 promonocytes and other human myeloid leukemia cell lines (HL-60, NB4). This effect was potentiated by cotreatment with the phosphatidylinositol 3-kinase (PI3K) inhibitors LY294002 and wortmannin, and the Akt inhibitor Akt(i)5. However, the inhibitors did not increase the toxicity of the mitochondria-targeting drug lonidamine, and the DNA-specific drugs camptothecin and cisplatin, when used under similar experimental conditions as As2O3. The potentiation of As2O3-provoked apoptosis involved the increased disruption of mitochondrial transmembrane potential, increased caspase-3 activation and cytochrome c release from mitochondria, increased Bax and Bid activation, and attenuation of 27-kDa heat shock protein (HSP27) expression; the potentiation was prevented by Bcl-2 overexpression. The PI3K/Akt inhibitors decreased the intracellular glutathione content, and caused intracellular oxidation, as measured by peroxide accumulation. Cotreatment with subcytotoxic concentrations of hydrogen peroxide increased apoptosis induction by As2O3. On the other hand, the treatments did not significantly affect glutathione S-transferase pi expression and activity. These results, which indicate that glutathione is a target of PI3K/Akt in myeloid leukemia cells, may partially explain the selective increase of As2O3 toxicity by PI3K/Akt inhibitors, and may provide a rationale to improve the efficacy of these inhibitors as therapeutic agents.",
Arsenic,656791,"Cell type specificity of lung cancer associated with arsenic ingestion Abstract: Arsenic is a well-documented human carcinogen. Previous studies on urinary bladder and skin cancers have shown that arsenic can cause specific cell types of malignancy. To evaluate whether this is also true for lung cancers, we conducted a study on 243 townships in Taiwan. We identified patients through the National Cancer Registry Program and compared the proportion of each major cell type between an endemic area of arsenic intoxication with exposures through drinking water, which includes 5 of the townships and the other 238 townships. To control for gender and age, we analyzed data on men and women separately and divided patients into four age groups. A total of 37,290 lung cancer patients, including 26,850 men and 10,440 women, was diagnosed between January 1, 1980 and December 31, 1999 in study townships. Patients from the endemic area had higher proportions of squamous cell and small cell carcinomas, but a lower proportion of adenocarcinomas. These findings were similar across all age groups in both genders, although the lack of data on smoking is a limitation of our study. The results suggested that the carcinogenicity of arsenic on lungs is also cell type-specific: squamous cell and small cell carcinomas appeared to be related to arsenic ingestion, but not adenocarcinoma. Whereas data in the literature are limited, the association between adenocarcinoma and arsenic exposures through inhalation appeared to be stronger than that of squamous cell carcinoma. Therefore, we speculate that arsenic may give rise to different mechanisms in the development of lung cancers through different exposure routes.",
Arsenic,1579320,"Biochar addition to an arsenic contaminated soil increases arsenic concentrations in the pore water but reduces uptake to tomato plants (Solanum lycopersicum L.) Abstract: Arsenic (As) concentrations in soil, soil pore water and plant tissues were evaluated in a pot experiment following the transplantation of tomato (Solanum lycopersicum L.) plantlets to a heavily As contaminated mine soil (~6000mgkg(-1) pseudo-total As) receiving an orchard prune residue biochar amendment, with and without NPK fertiliser. An in-vitro test was also performed to establish if tomato seeds were able to germinate in various proportions of biochar added to nutrient solution (MS). Biochar significantly increased arsenic concentrations in pore water (500?gL(-1)-2000?gL(-1)) whilst root and shoot concentrations were significantly reduced compared to the control without biochar. Fruit As concentrations were very low (<3?gkg(-1)), indicating minimal toxicity and transfer risk. Fertilisation was required to significantly increase plant biomass above the control after biochar addition whilst plants transplanted to biochar only were heavily stunted and chlorotic. Given that increasing the amount of biochar added to nutrient solution in-vitro reduced seed germination by up to 40%, a lack of balanced nutrient provision from biochar could be concluded. In summary, solubility and mobility of As were increased by biochar addition to this soil, but uptake to plant was reduced, and toxicity-transfer risk was negligible. Therefore leaching rather than food chain transfer appears the most probable immediate consequence of biochar addition to As contaminated soils.",
Arsenic,2088498,"Cytotoxic Effects of Polystyrene-Titanium-Arsenate Composite in Cultured H9c2 Cardiomyoblasts Abstract: In the present report, we explored the toxicological behaviour of engineered polystyrene-titanium-arsenate (PS-Ti-As) composite using cultured H9c2 cardiomyoblasts in vitro. From in vitro cytotoxicity studies, it appears that the composite can be toxic to the cardiac cells and the value of IC50 investigated to be the highest concentration of 500 ?g mL(-1), during 16-24 h of incubation period. The cell morphological studies based on dual staining with acridine orange and ethidium bromide indicates that apoptosis is the dominating pathway of cell death. Furthermore, an enhanced DNA fragmentation, increased reactive oxygen species production and caspase release demonstrates the potential risks associated with the exposure of PS-Ti-As composite to the cardiac cells.",
Arsenic,1026096,"An eight-year study report on arsenic contamination in groundwater and health effects in Eruani village, Bangladesh and an approach for its mitigation Abstract: Based on several surveys during 1997-2005 and visits of a medical team to Eruani village, Laksham upazila, Comilla district, Bangladesh, the arsenic contamination situation and consequent clinical manifestations of arsenicosis among the villagers, including dermatology, neuropathy, and obstetric outcome, are reported here. Analysis of biological samples from patients and non-patients showed high body burden of arsenic. Even after eight years of known exposure, village children were still drinking arsenic-contaminated water, and many of them had arsenical skin lesions. There were social problems due to the symptoms of arsenicosis. The last survey established that there is a lack of proper awareness among villagers about different aspects of arsenic toxicity. The viability of different options of safe water, such as dugwells, deep tubewells, rainwater harvesting, and surface water with watershed management in the village, was studied. Finally, based on 19 years of field experience, it was felt that, for any successful mitigation programme, emphasis should be given to creating awareness among villagers about the arsenic problem, role of arsenic-free water, better nutrition from local fruits and vegetables, and, above all, active participation of women along with others in the struggle against the arsenic menace.",
Arsenic,1519037,"Linking geological and health sciences to assess childhood lead poisoning from artisanal gold mining in Nigeria Abstract: Background: In 2010, Médecins Sans Frontières discovered a lead poisoning outbreak linked to artisanal gold processing in northwestern Nigeria. The outbreak has killed approximately 400 young children and affected thousands more. Objectives: Our aim was to undertake an interdisciplinary geological- and health-science assessment to clarify lead sources and exposure pathways, identify additional toxicants of concern and populations at risk, and examine potential for similar lead poisoning globally. Methods: We applied diverse analytical methods to ore samples, soil and sweep samples from villages and family compounds, and plant foodstuff samples. Results: Natural weathering of lead-rich gold ores before mining formed abundant, highly gastric-bioaccessible lead carbonates. The same fingerprint of lead minerals found in all sample types confirms that ore processing caused extreme contamination, with up to 185,000 ppm lead in soils/sweep samples and up to 145 ppm lead in plant foodstuffs. Incidental ingestion of soils via hand-to-mouth transmission and of dusts cleared from the respiratory tract is the dominant exposure pathway. Consumption of water and foodstuffs contaminated by the processing is likely lesser, but these are still significant exposure pathways. Although young children suffered the most immediate and severe consequences, results indicate that older children, adult workers, pregnant women, and breastfed infants are also at risk for lead poisoning. Mercury, arsenic, manganese, antimony, and crystalline silica exposures pose additional health threats. Conclusions: Results inform ongoing efforts in Nigeria to assess lead contamination and poisoning, treat victims, mitigate exposures, and remediate contamination. Ore deposit geology, pre-mining weathering, and burgeoning artisanal mining may combine to cause similar lead poisoning disasters elsewhere globally.",
Arsenic,2337189,"Origin of Arsenic in Groundwater from the Multilayer Aquifer in Cremona (Northern Italy) Abstract: An analysis of 70 wells that tap groundwater from depths of up to 260 m in and around the town of Cremona, N. Italy, shows that 50 of them contain more than 10 ?g/L of arsenic. Concentrations of As &gt;10 ppb are accompanied by concentrations of Fe ranging from &lt;0.1 to 6 mg/L and high concentrations of NH4 and Mn (&lt;19 and &lt;1.3 mg/L, respectively). The associations suggest that the mechanism of mobilization of As is the reductive dissolution of Fe oxides driven by the degradation of peat, which is commonly found in the aquifer system. Groundwater in the aquifer has a component of downward flow via leakage through aquitards and flow through lateral discontinuities in them. Along these flow paths, As is released by reductive dissolution of Fe oxides in shallow and intermediate aquifers (0-85 m below surface), reaching up to 183 ?g/L, and is attenuated (&lt;95 ?g/L) at greater depths (100-150 m). Coprecipitation in iron sulfides could play an important role in As attenuation at these depths. The lower As concentration (&lt;37 ?g/L) in the deepest aquifer (160-260 m) is less related to the As concentration of the overlying aquifers because the groundwater here has a component of upward flow.",
Arsenic,1936114,"Pilot study of natural attenuation of arsenic in well water discharged to the Little River above Lake Thunderbird, Norman, Oklahoma, 2012 Abstract: The City of Norman, Oklahoma, wanted to augment its water supplies to meet the needs of an increasing population. Among the citys potential water sources are city wells that produce water that exceeds the 10 micrograms per liter primary drinking-water standard for arsenic. The City of Norman was interested in investigating low-cost means of using natural attenuation to remove arsenic from well water and augment the water supply of Lake Thunderbird, the primary water source for the city. The U.S. Geological Survey, in cooperation with the City of Norman, conducted a preliminary investigation (pilot study) to determine if discharge of water from those wells into the Little River over a 12-day period would reduce arsenic concentrations through natural-attenuation processes. Water in the Little River flows into Lake Thunderbird, the principal water source for the city, so the discharged well water would improve the water balance of that reservoir. During this pilot study, 150–250 gallons per minute from each of six city wells were discharged to the Little River over a 12-day period. Water-quality samples were collected from the wells during discharge and from the river before, during, and after well discharges. Streambed-sediment samples were collected at nine sites in the river before and after the well-discharge period. Water discharge from the six wells added 0.3 kilogram per day of arsenic to the river at the nearest downstream streamflow-gaging station. Dissolved arsenic concentration in the Little River at the closest downstream sampling site from the wells increased from about 4 micrograms per liter to as much as 24 micrograms per liter. Base flow in the river increased by about 1.7 cubic feet per second at the nearest downstream streamflow-gaging station. Streamflow in the river was two-thirds of that expected from the amount of water discharged from the wells because of seepage to soils and evapotranspiration of well water along drainage ways to the river. Arsenic concentrations at the nearest downstream streamflow-gaging station were less than arsenic concentrations measured in many of the well-water samples during the well-pumping period. Arsenic concentrations, loads, and yields in the Little River generally decreased downstream from the closest streamflow-gaging station to the wells by 50 percent or more, indicating removal of about 0.25 kilogram or 0.53 pound per day of arsenic during base-flow conditions. Measured river-water arsenic concentrations near the confluence of the Little River with Lake Thunderbird were in compliance with the primary drinking-water standard. Arsenic concentrations measured at four downstream stations in the Little River also were less than established criteria set for protection of aquatic biota. After well discharges to the Little River were stopped, arsenic concentrations, loads, and yields in the river gradually decreased over 14 days to concentrations measured prior to the well-water discharges. Cumulative loads of arsenic discharged at the wells and the closest and farthest downstream streamflow-gaging stations indicated removal of about 2.5 kilograms of arsenic as well-water flowed to and down the river. Arsenic concentrations in streambed-sediment samples collected before and after the well-water discharges were not significantly different. Results of this pilot study indicate that using natural-attenuation processes to remove arsenic from water and supplement city water supplies may be a viable, relatively low-cost method for attenuating arsenic in well water and for augmenting the water supply of Lake Thunderbird.",
Arsenic,627291,"Arsenic level in drinking water and mortality of lung cancer (Taiwan) Abstract: OBJECTIVE: Lung cancers have been observed among patients of arsenic intoxication since the 1950s, but data on the dose-response relationship were limited. In order to obtain such data, a study was conducted in ten townships in Taiwan. METHODS: Measurements of arsenic levels in drinking water were available for 138 villages from a census survey conducted by the government. Certificates of deaths that occurred in the villages between January 1, 1971 and December 31, 1990 were reviewed, and 673 male and 405 female mortality cases of lung cancer were identified. Multi-variate regression models were applied to assess associations between arsenic levels in drinking water and mortality of lung cancer using village as the unit. RESULTS: After adjusting for age, arsenic levels above 0.64 mg/l were associated with a significant increase in the mortality of lung cancer in both genders, but no significant effect was observed at lower levels. Post-hoc analyses confirmed such a dose-response relationship. CONCLUSIONS: The results indicate a prominent carcinogenic effect of high arsenic levels in drinking water on the lung and suggest the new 'maximum contaminant level' of 10 micro g/l published by the US Environmental Protection Agency provides sufficient protection against lung cancer. Nonetheless, further studies with exposure data on individuals are warranted to confirm these findings.",
Arsenic,1015718,"Age-related effects of sodium arsenite on splenocyte proliferation and Th1/Th2 cytokine production Abstract: Aging is associated with immune dysfunction and conditions such as inflamm-aging and immunosuppression. Arsenic, an environmental contaminant distributed worldwide, affects the immune system. This study tested the hypothesis that arsenic has distinct effects on T cell proliferation and the production of cytokines by activated T cells. Murine splenocytes from young (2 months) and aged (24-26 months) C57BL/6 mice were exposed to arsenite (As(3+)), the most toxic form of inorganic arsenic, and stimulated with concanavalin A (Con A) or anti-CD3 antibody. T cell proliferation decreased significantly in response to Con A and anti-CD3 at subtoxic doses of arsenite in splenocytes from both young and aged mice. Arsenite, added concurrently with Con A or anti-CD3, significantly inhibited the production of interleukin-2 (IL-2), interferon-? (IFN-?), and interleukin-4 (IL-4) by splenocytes from young mice and significantly reduced the production of IL-10 by splenocytes from aged mice. In contrast, the production of IL-2 and IL-4 by splenocytes from aged mice was only slightly affected by arsenite. The results show that arsenic exposure reduces the immune response in splenocytes. Moreover, this effect may be influenced by aging.",
Arsenic,2345766,"Health effects and arsenic species in urine of copper smelter workers Abstract: The aim of this study was to compare indices of exposure in workers employed at different work posts in a copper smelter plant using neurophysiological tests and to evaluate the relationship between urinary arsenic species with the aid of sensitive respiratory and renal biomarkers. We have attempted to elucidate the impact of different arsenic speciation forms on the observed health effects. We focused on the workers (n = 45) exposed to atmospheres containing specific diverse mixtures of metals (such as those occurring in Departments of Furnaces, Lead and Electrolysis) compared to controls (n = 16). Subjective symptoms from the central (CNS) and the peripheral (PNS) nervous system were recorded and visual evoked potential (VEP), electroneurography (ENeG) and electroencephalography (EEG) curves were analysed. Levels of airborne lead (PbA), zinc (ZnA) and copper (CuA) and Pb levels in blood (PbB) and the relationships between airborne As concentrations (AsA) and the urinary levels of the inorganic (iAs); As(+3), As(+5) and the organic; methylarsonate (MMA(V)), dimethylarsinate (DMA(V)) and arsenobetaine (AsB) arsenic species were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Effects of exposure were expressed in terms of biomarker levels: Clara cell protein (CC16) in serum as early pulmonary biomarker and ?2-microglobulin (?2M) in urine and serum, retinol binding protein (RBP) as renal markers, measured by sensitive latex-immunoassay (LIA). Abnormal results of neurophysiological tests, VEP, EEG and ENeG showed dominant subclinical effects in CNS and PNS of workers from Departments of Lead and Furnace. In group of smelters from Departments of Furnace exposed to arsenic above current TLV, excreted arsenic species As(+3) and As(+5) seemed to reduce the level of Clara cell protein (CC16), thereby reducing anti-inflammatory potential of the lungs and increasing the levels of renal biomarker (?2M) and copper in urine (CuU). The study confirmed deleterious arsenic effects to the kidney by increased levels of low-molecular weight protein in urine and the extent of the renal copper accumulation/excretion. The results of our work also support the usefulness of application of the sensitive neurophysiologic tests, such as VEP, EEG and ENeG, for the detection of early subclinical effects of the exposure of the nervous system in copper smelters.",
Arsenic,1337316,"Blood pressure hyperreactivity: An early cardiovascular risk in normotensive men exposed to low-to-moderate inorganic arsenic in drinking water Abstract: BACKGROUND:: Essential hypertension is associated with chronic exposure to high levels of inorganic arsenic in drinking water. However, early signs of risk for developing hypertension remain unclear in people exposed to chronic low-to-moderate inorganic arsenic. OBJECTIVE:: We evaluated cardiovascular stress reactivity and recovery in healthy, normotensive, middle-aged men living in an arsenic-endemic region of Romania. METHODS:: Unexposed (n?=?16) and exposed (n?=?19) participants were sampled from communities based on WHO limits for inorganic arsenic in drinking water (&lt;10??g/l). Water sources and urine samples were collected and analyzed for inorganic arsenic and its metabolites. Functional evaluation of blood pressure included clinical, anticipatory, cold pressor test, and recovery measurements. Blood pressure hyperreactivity was defined as a combined stress-induced change in SBP (&gt;20?mmHg) and DBP (&gt;15?mmHg). RESULTS:: Drinking water inorganic arsenic averaged 40.2?±?30.4 and 1.0?±?0.2??g/l for the exposed and unexposed groups, respectively (P?&lt;?0.001). Compared to the unexposed group, the exposed group expressed a greater probability of blood pressure hyperreactivity to both anticipatory stress (47.4 vs. 12.5%; P?=?0.035) and cold stress (73.7 vs. 37.5%; P?=?0.044). Moreover, the exposed group exhibited attenuated blood pressure recovery from stress and a greater probability of persistent hypertensive responses (47.4 vs. 12.5%; P?=?0.035). CONCLUSIONS:: Inorganic arsenic exposure increased stress-induced blood pressure hyperreactivity and poor blood pressure recovery, including persistent hypertensive responses in otherwise healthy, clinically normotensive men. Drinking water containing even low-to-moderate inorganic arsenic may act as a sympathetic nervous system trigger for hypertension risk.",
Arsenic,1347765,"Direct determination of arsenic in beer by electrothermal atomic absorption spectrometry with deuterium background correction (D-2-ET-AAS) Abstract: We describe here a method for the direct determination of As in beer by D2-ET-AAS, using Pd modifier, the atomization from platform and insertion of a cooling step before atomization. This method results in a 40% increase of sensitivity in peak-height measurements. Pd was found to be the most advantageous chemical modifier for the elimination of phosphate interference compared to Ni or Pt + citric acid. In addition, Pd is able to stabilize As at charring temperatures of 1500 °C and further addition of V, Mg or Sr have no influence. Addition of the modifier to standards and samples made possible the use of matrix-free standard solutions for attaining accurate analysis of diluted samples. The accuracy was checked by the comparison of results of direct analysis of beer samples by the proposed method with those found for microwave-digested samples measured by an inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP-oa-TOFMS) method. The accuracy was also confirmed by the analysis of certified reference samples.",
Arsenic,2279231,"Association of the type of 5q loss with complex karyotype, clonal evolution, TP53 mutation status, and prognosis in acute myeloid leukemia and myelodysplastic syndrome Abstract: We analyzed 1,200 patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) harboring a 5q deletion in order to clarify whether the type of 5q loss is associated with other biological markers and prognosis. We investigated all patients by chromosome banding analysis, FISH with a probe for EGR1 (5q31) and, if necessary, to resolve complex karyotypes with 24-color-FISH. Moreover, 420 patients were analyzed for mutations in the TP53 gene. The patient cohort was subdivided based on type of 5q loss: Patients with interstitial deletions and patients with 5q loss due to unbalanced rearrangements or monosomy 5. Loss of the long arm of chromosome 5 due to an unbalanced rearrangement occurred more often in AML (286/627; 45.6%) than MDS (188/573; 32.8%; P?&lt;?0.001). In both entities, patients with 5q loss due to unbalanced translocations showed complex karyotypes more frequently (MDS: 179/188; 95.2% vs. 124/385; 32.2%; P?&lt;?0.001; AML: 274/286; 95.8% vs. 256/341; 75.1%; P?&lt;?0.001). Moreover, in MDS unbalanced 5q translocations were associated with clonal evolution (109/188; 58.0% vs. 124/385; 32.2%; P?&lt;?0.001), mutation of TP53 (64/67; 95.5% vs. 40/120; 40.0%; P?&lt;?0.001), and shorter survival (15.3 months vs. not reached; P?&lt;?0.001). In MDS, complex karyotype was an independent adverse prognostic factor (HR?=?5.34; P?=?0.032), whereas in AML presence of TP53 mutations was the strongest adverse prognostic factor (HR?=?2.21; P?=?0.026). In conclusion, in AML and MDS, loss of the long arm of chromosome 5 due to unbalanced translocations is associated with complex karyotype and in MDS, moreover, with clonal evolution, mutations in the TP53 gene and adverse prognosis. © 2014 Wiley Periodicals, Inc.",
Arsenic,569029,"Cytogenetic insights into DNA damage and repair of lesions induced by a monomethylated trivalent arsenical Abstract: Arsenic is a human carcinogen, and only recently animal models have been developed that are useful in investigating its carcinogenic mode of action (MOA). However, how arsenic induces cancer is still an open question. In a previous paper, we proposed a model detailing how arsenic might induce DNA lesions leading to cytogenetic damage [A.D. Kligerman, A.H. Tennant, Toxicol. Appl. Pharmacol. 222 (2007) 281-288]. In this model we hypothesized that arsenic does not induce chromosome damage via DNA adduction but induces short-lasting lesions from the action of reactive oxygen species (ROS). These lesions cause single-strand breaks (SSB) that induce chromosome breakage when treatment is in late G1- or S-phase. However, if treatment is confined to the G0- or early G1-phase of the cell cycle, it is predicted that little or no cytogenetic damage will result at the subsequent metaphase. Here, we describe the results from testing this model using monomethylarsonous acid (MMAIII) and cytosine arabinoside (araC), a DNA chain terminator, to extend the time that DNA lesions remain open during repair to allow the lesions to reach S-phase or interact to form DNA exchanges that would lead to exchange aberrations at metaphase. The results of our study only partially confirmed our hypothesis. Instead, the results indicated that the lesions induced by MMAIII are quickly repaired through base excision repair, that there is little chance for araC to extend the life of the lesions, and thus the DNA damage induced by arsenicals that leads to chromosome aberrations is very short lived.",
Arsenic,1380809,"Gallium arsenide-induced increase in serum corticosterone is not responsible for suppression of the IgM antibody response Abstract: Previous investigations demonstrated gallium arsenide (GaAs) to be an immunosuppressive agent that alters the function of all cell types involved in the generation of a primary antibody response. In those studies, GaAs was administered as a particulate compound that remained in the lung at least 14 days after exposure. The extended presence of the particulate in the lung may induce a stress response that leads to the release of endogenous corticosteroids. In addition, some of the observed immunomodulatory effects of GaAs were similar to immunological alterations reported to be induced by corticosteroids. The present studies were designed to determine whether suppression of the immunoglobulin (Ig) M antibody-forming calls (AFC) response by GaAs was a result of a GaAs-induced increase in serum corticosterone. GaAs (50-200 mg/kg) significantly decreased the weights of both the thymus and spleen and the cellularity of the spleen. In addition, there was a GaAs-induced decrease in the CD4+/CD8+ thymocyte subpopulations and a concomitant increase in CD4+ and CD8+ cells. Within the spleen, there were no alterations in the percentages of CD4, CD8 or Ig-positive cells. However, when expressed as an absolute cell number, there was a 50% decrease in the numbers of CD4+ and CD8+ cells in the spleen. GaAs also dose-dependently suppressed (50-75%) the IgM AFC response. The GaAs-induced changes in cell populations and immune organ weights were correlated with an increase (6- to 10-fold) in serum corticosterone levels. The treatment of mice with the glucocorticoid antagonist mifepristone (also called RU 486) blocked the observed alterations in splenic and thymic cell populations induced by GaAs.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,1597430,"Phosphate adsorption from aqueous solutions onto goethite, bentonite, and bentonite-goethite system Abstract: The present paper examines the phosphate adsorption from aqueous solutions onto goethite, bentonite, and bentonite–goethite system. The properties of the materials were studied by X-ray diffraction (XRD), attenuated total reflectance (ATR), and NMR spectra and by the measurement of the specific surface area, the point of zero charge (p.z.c.) and the pore-specific volume. ATR and NMR spectra of bentonite and bentonite–goethite system show peaks which correspond to tetrahedrally and octahedrally coordinated Al. The specific surface area of the system differs according to the appropriate method used, while system’s p.z.c. is higher than bentonite and lower than goethite. The pore-specific volume of bentonite–goethite system is higher than that of bentonite or goethite. According to XRD spectrum of bentonite–goethite system, goethite coats the (001) spacing of bentonite while the coating of (010) plane of bentonite is limited. The crystallinity of the system decreases and the negative permanent charge increases. Phosphate adsorption experiments took place at different pH (3.8–9.0) and concentrations (40.3–443.5 ?mol?L?1) and constant capacitance model was applied to describe adsorption. A ligand exchange mechanism characterizes the model because the charge is divided among adsorbate and adsorbent. The constant capacitance model describes the adsorption mechanism in all examined pH. This model can be utilized in such systems using the surface protonation-dissociation constant of goethite and showing the exact shape of the adsorption isotherms for different pH values. ?he produced low-cost bentonite–goethite system presents the highest adsorption of P per kilogram of goethite.",
Arsenic,1337579,"Burden of skin lesions of arsenicosis at higher exposure through groundwater of taluka Gambat district Khairpur, Pakistan: A cross-sectional survey Abstract: Prior surveys conducted have found higher proportion of arsenic-contaminated wells in villages along river Indus in Pakistan. This study aims to determine the prevalence of arsenicosis skin lesions among population exposed to higher exposure in taluka Gambat district Khairpur in Sindh. The cross-sectional survey was conducted from August 2008 to January 2009 among 610 households. A total of 707 water sources (hand pumps/wells) were tested from the villages of union councils of Agra and Jado Wahan for arsenic levels with Quick rapid arsenic field test kits. A total of 110 households exposed to arsenic levels >50 ppb were identified. Case screening for arsenic skin lesions was performed for 610 individuals residing in these 110 high-risk households. Information regarding household and socio-demographic characteristics, height and weight measurements and arsenic exposure assessment were collected. Physical examinations by trained physicians were carried out to diagnose the arsenic skin lesions. After data cleaning, 534 individuals from all age groups were included in the final analysis which had complete exposure and outcome information. Overall prevalence of arsenicosis skin lesions was 13.5 % (72 cases). Of the 534 individuals, 490 (91.8 %) were exposed to arsenic levels of ?100 ppb in drinking water (8.2 % to >50-99 ppb, 58.6 % to 100-299 ppb, 14.6 % to 300-399 ppb and 18 % to ?400 ppb). Prevalence rate (per 100 population) of arsenicosis was highest at arsenic levels of 100-199 ppb (15.2 cases) followed by ?400 ppb (13.5 cases) and 300-399 (12.8 cases). Prevalence rate was higher among females (15.2) compared to males (11.3). Our study reports arsenicosis burden due to exposure to higher arsenic levels in drinking water in Pakistan. Exposure to very high levels of arsenic in drinking water calls for urgent action along river Indus. Prevalence of skin lesions increases with increasing arsenic levels in drinking groundwater. Provision of arsenic-free drinking water is essential to avoid current and future burden of arsenicosis in Pakistan.",
Arsenic,1016064,"The association between total urinary arsenic concentration and renal dysfunction in a community-based population from central Taiwan Abstract: Arsenic (As) is an important environmental toxicant that can cause cancer and cardiovascular disease, but the relationship between As exposure and renal dysfunction is not clear. The aim of this study is to examine the association between As exposure and renal dysfunction in a community-based population in central Taiwan. One thousand and forty-three subjects were recruited between 2002 and 2005. The risk for type 2 diabetes was increased by 2-fold (p&lt;0.05) in subjects with total urinary As (U-As)&gt;75 ?g g(-1) creatinine as compared with subjects whose U-As was ? 35 ?g g(-1) creatinine after the adjustment for potential confounders. The adjusted odds ratio for an abnormal ?2 microglobulin (B2MG&gt;0.154 mg L(-1)) was significantly higher in subjects with U-As&gt;35 ?g g(-1) creatinine as compared with the reference group adjusted for age, sex, living area, cigarette smoking, diabetes, and hypertension. The risk for abnormal B2MG and estimated glomerular filtration rate (eGFR&lt;90 mL min(-1)(1.73 m(2))(-1)) was both increased around 2-fold (p&lt;0.05) in subjects with U-As&gt;75 ?g g(-1) creatinine as compared with those with U-As ? 35 ?g g(-1) creatinine adjusted for all the risk factors plus lead (Pb), cadmium and nickel. The prevalence of abnormal B2MG was 4.82 times higher in subjects with both over the median levels of U-As (85.1 ?g L(-1)) and urinary Pb (18.9 ?g L(-1)) as compared to both lower than the median (p&lt;0.001). These results indicate that U-As might relate to renal dysfunction even other important risk factors were taken into account. Follow-up studies for causal inference are warranted.",
Arsenic,1337340,"Toxic element contamination of natural health products and pharmaceutical preparations Abstract: <strong>BACKGROUND: </strong>Concern has recently emerged regarding the safety of natural health products (NHPs)-therapies that are increasingly recommended by various health providers, including conventional physicians. Recognizing that most individuals in the Western world now consume vitamins and many take herbal agents, this study endeavored to determine levels of toxic element contamination within a range of NHPs.<br /><br /><strong>METHODS: </strong>Toxic element testing was performed on 121 NHPs (including Ayurvedic, traditional Chinese, and various marine-source products) as well as 49 routinely prescribed pharmaceutical preparations. Testing was also performed on several batches of one prenatal supplement, with multiple samples tested within each batch. Results were compared to existing toxicant regulatory limits.<br /><br /><strong>RESULTS: </strong>Toxic element contamination was found in many supplements and pharmaceuticals; levels exceeding established limits were only found in a small percentage of the NHPs tested and none of the drugs tested. Some NHPs demonstrated contamination levels above preferred daily endpoints for mercury, cadmium, lead, arsenic or aluminum. NHPs manufactured in China generally had higher levels of mercury and aluminum.<br /><br /><strong>CONCLUSIONS: </strong>Exposure to toxic elements is occurring regularly as a result of some contaminated NHPs. Best practices for quality control-developed and implemented by the NHP industry with government oversight-is recommended to guard the safety of unsuspecting consumers.",
Arsenic,1797814,"Association between in utero arsenic exposure, placental gene expression, and infant birth weight: A US birth cohort study Abstract: <strong>BACKGROUND: </strong>Epidemiologic studies and animal models suggest that in utero arsenic exposure affects fetal health, with a negative association between maternal arsenic ingestion and infant birth weight often observed. However, the molecular mechanisms for this association remain elusive. In the present study, we aimed to increase our understanding of the impact of low-dose arsenic exposure on fetal health by identifying possible arsenic-associated fetal tissue biomarkers in a cohort of pregnant women exposed to arsenic at low levels.<br /><br /><strong>METHODS: </strong>Arsenic concentrations were determined from the urine samples of a cohort of 133 pregnant women from New Hampshire. Placental tissue samples collected from enrollees were homogenized and profiled for gene expression across a panel of candidate genes, including known arsenic regulated targets and genes involved in arsenic transport, metabolism, or disease susceptibility. Multivariable adjusted linear regression models were used to examine the relationship of candidate gene expression with arsenic exposure or with birth weight of the baby.<br /><br /><strong>RESULTS: </strong>Placental expression of the arsenic transporter AQP9 was positively associated with maternal urinary arsenic levels during pregnancy (coefficient estimate: 0.25; 95% confidence interval: 0.05 -- 0.45). Placental expression of AQP9 related to expression of the phospholipase ENPP2 which was positively associated with infant birth weight (coefficient estimate: 0.28; 95% CI: 0.09 -- 0.47). A structural equation model indicated that these genes may mediate arsenic's effect on infant birth weight (coefficient estimate: -0.009; 95% confidence interval: -0.032 -- -0.001; 10,000 replications for bootstrapping).<br /><br /><strong>CONCLUSIONS: </strong>We identified the expression of AQP9 as a potential fetal biomarker for arsenic exposure. Further, we identified a positive association between the placental expression of phospholipase ENPP2 and infant birth weight. These findings suggest a path by which arsenic may affect birth outcomes.",
Arsenic,711017,"Prevention of arsenic-induced hepatic apoptosis by concomitant administration of garlic extracts in mice Abstract: Garlic is well known as a folk remedy for a variety of ailments since ancient times, however, very few studies are available suggesting its beneficial role against arsenic toxicity pertaining to its ability to eliminate arsenic from the blood and soft tissues and in reversal of arsenic-induced oxidative stress in affected tissues. The present study was planned to investigate the protective efficacy of aqueous garlic extract using two different doses on parameters suggestive of hepatic injury, tissue oxidative stress and mobilization of arsenic. Further, an attempt to understand the mechanism of arsenic in inducing hepatic apoptosis was also studied. Results of the present study suggested that arsenic administration in mice caused generation of reactive oxygen species (ROS) causing apoptosis through mitochondria-mediated pathway. The ROS generation in hepatic tissue reverted to normal values after co-administration of garlic extracts. The study provides significant evidence that garlic extracts contain strong anti-oxidant property which could be beneficial in preventing arsenic-induced toxicity in cells. However, further research is required to determine whether the results from animal studies are applicable to humans before garlic can be recommended as a putative agent against arsenic toxicity.",
Arsenic,448752,"Drinking-water arsenic exposure modulates gene expression in human lymphocytes from a U.S. population Abstract: BACKGROUND: Arsenic exposure impairs development and can lead to cancer, cardiovascular disease, and diabetes. The mechanism underlying these effects remains unknown. Primarily because of geologic sources of contamination, drinking-water arsenic levels are above the current recommended maximum contaminant level of 10 mu g/L in the northeastern, western, and north central regions of the United States. OBJECTIVES: We investigated the effects of arsenic exposure, defined by internal biomarkers at levels relevant to the United States and similarly exposed populations, on gene expression. METHODS: We conducted separate Affymetrix microarray-based genomewide analyses of expression patterns. Peripheral blood lymphocyte samples from 21 controls interviewed (1999-2002) as part of a case-control study in New Hampshire were selected based on high- versus low-level arsenic exposure levels. RESULTS: The biologic functions of the transcripts that showed statistically significant abundance differences between high- and low-arsenic exposure groups included an overrepresentation of genes involved in defense response, immune function, cell growth, apoptosis, regulation of cell cycle, T-cell receptor signaling pathway, and diabetes. Notably, the high-arsenic exposure group exhibited higher levels of several killer cell immunoglobulin-like receptors that inhibit natural killer cell activity. CONCLUSIONS: These findings define biologic changes that occur with chronic arsenic exposure in humans and provide leads and potential targets for understanding and monitoring the pathogenesis of arsenic-induced diseases.",
Arsenic,1340137,"Arsenic and chromium in sea foods from Niger Delta of Nigeria: a case study of Warri, Delta State Abstract: This study determined the concentration of Arsenic and Chromium in sea foods samples from Ethiope River. The sea foods were bought from different locations along the bank of the river. Arsenic concentration ranged from 0.046 ± 0.01 to 0.083 ± 0.05 mg/kg, while the chromium concentration ranged from 0.079 ± 0.04 to 0.152 ± 0.14 mg/kg. Palaemon serratus has the highest concentration of arsenic and chromium, 152 ± 0.14 mg/kg and 0.081 ± 0.04 mg/kg respectively, while Harengula jaguana has the lowest concentration of arsenic and chromium, 0.079 ± 0.04 mg/kg and 0.046 ± 0.01 mg/kg respectively. There are various oil prospecting companies and oil and gas related industries in this area which discharge untreated waste products into Ethiope River. In view of this, there is need to determine the level of arsenic and chromium contamination of the river, since the inhabitants depend on the river for fishing and other domestic uses.",
Arsenic,1027390,"ABSORPTION OF ARSENIC FOLLOWING INTRA-MUSCULAR INJECTIONS OF SALVARSAN AND NEOSALVARSAN Abstract: Intramuscular injection of salvarsan and neosalvarsan in rabbits always produces necrosis of the muscles. A much more intense reaction is produced by salvarsan than by neosalvarsan. The rate of absorption of arsenic following intramuscular injections of salvarsan is very slow, while following intramuscular injections of neosalvarsan between 75 and 85 per cent of the arsenic is absorbed during the first week. The subsequent absorption is quite slow.",
Arsenic,1358644,"Synergism and antagonism of arsenic, chromium and fluoride on nitrification process Abstract: Based on the experimental data obtained for nitrification in a fixed film packed bed reactor, a rate expression of the following form has been developed under the shock load of trivalent arsenic, hexavalent chromium and fluoride, in pair: (image of formula) where I1 is the concentration of the stronger inhibitor and I2, that of the weaker one in the pair. In the expression, k is equal to 4 for the chromium arsenic and arsenic?fluoride combinations while for the chromium?fluoride combination it is equal to 3. ßj is the regression coefficient of the polynomial curve fit. Amongst chromium, arsenic and fluoride, which non?competitively inhibit nitrification, chromium is most inhibitory while fluoride, the least. Under the simultaneous presence of any two of these, the mode of inhibition has been characterised in terms of synergism and antagonism. Interaction factor V, has been introduced to quantitatively take these phenomena into account. ¥ has been corelated to the experimental data by the following expression: (image of formula) The physical significance of ? is that the interaction between I, and I2 is synergistic for ? greater than unity and antagonistic for ? less than unity. It is additive when ? is equal to unity. The analysis of the data shows that synergestic inhibition occurs upto 26.0 and 29.0 mgl?1 of chromium for corresponding arsenic concentrations of 75.0 and 150.0 mgl?1 , respectively. The same phenomenon takes place upto 26.0, 23.6, 16.0 and 14.4 mgl?1 of chromium corresponding to fluoride concentrations of 150.0, 300.0, 600.0 and 800.0 mgl?1 , respectively. Arsenic suppresses nitrification synergistically upto 200.0, 180.0, 145.0 and 125.0 mgl?1 for fluoride concentrations of 300.0, 150.0, 600.0 and 800.0 mgl?1 , respectively. Beyond the above concentrations of chromium and arsenic, the effect is found to be antagonistic.",
Arsenic,711024,"Pulmonary injury and antioxidant response in mice exposed to arsenate and hexavalent chromium and their combination Abstract: Chromated copper arsenate, which is used worldwide as a wood preservative, can adversely affect human health. Accumulating evidence suggests that chromium (Cr) and arsenic (As) can potentially disrupt the redox balance and cause respiratory diseases and cancer in humans. The present study was designed to determine the combined toxic effects of these metals in the lungs and to clarify the specific molecules that are stimulated by combined exposure to both metals. Male C57BL/6J mice were intratracheally instilled with arsenate [As(V)], hexavalent chromium [Cr(VI)], or a combination of both metals. Mice were sacrificed 2 days after treatment to collect bronchoalveolar lavage fluid and lung tissue samples. Inflammation, cytotoxicity, apoptosis, and oxidative stress markers were measured. Our results indicated that administration of Cr(VI) alone or in combination with As(V) induced neutrophil-dominant inflammation as well as phosphorylation of mitogen-activated protein kinases; effects of treatment with As(V) alone were comparatively less potent. By analyzing the production of interleukin-6 and activity of lactate dehydrogenase and caspase, we confirmed that co-treatment intensified pulmonary injury and that it was accompanied by oxidative stress, as confirmed by marked increases in the production of reactive oxygen species, reduced glutathione content, and thioredoxin reductase (TRXRD) activity. Expressed mRNA levels of heme oxygenase-1, glutamylcysteine ligase, glutathione peroxidase 2, thioredoxin (TRX) 1, and TRXRD1 were also enhanced by co-treatment, whereas treatment with As(V) alone reduced the mRNA expression level of TRX2. Our data suggest that co-treatment with As(V) exacerbated Cr(VI)-induced pulmonary injury and that this effect may be exerted through a disruption in the balance among several antioxidant genes.",
Arsenic,1936153,"Environmental lead exposure risks associated with children's outdoor playgrounds Abstract: This study examines exposure risks associated with lead smelter emissions at children's public playgrounds in Port Pirie, South Australia. Lead and other metal values were measured in air, soil, surface dust and on pre- and post-play hand wipes. Playgrounds closest to the smelter were significantly more lead contaminated compared to those further away (t(27.545) = 3.76; p = .001). Port Pirie post-play hand wipes contained significantly higher lead loadings (maximum hand lead value of 49,432 ?g/m(2)) than pre-play hand wipes (t(27) = 3.57, p = .001). A 1% increase in air lead (?g/m(3)) was related to a 0.713% increase in lead dust on play surfaces (95% CI, 0.253-1.174), and a 0.612% increase in post-play wipe lead (95% CI, 0.257-0.970). Contaminated dust from smelter emissions is determined as the source and cause of childhood lead poisoning at a rate of approximately one child every third day.",
Arsenic,2064144,Arsenic-induced changes in growth and antioxidant metabolism of fenugreek Abstract: ,
Arsenic,628341,"Bladder cancer mortality reduction after installation of a tap-water supply system in an arsenious-endemic area in southwestern Taiwan Abstract: Arsenic has been well documented as the major risk factor for blackfoot disease (BFD), a unique peripheral vascular disease that was endemic in the southwestern coast of Taiwan, where residents had consumed high-arsenic artesian well water for more than 50 years. Long-term arsenic exposure has also been reported to be associated with bladder cancer mortality in a dose-response relationship. A tap water supply system was implemented in the early 1960s in the BFD endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study is to examine whether bladder cancer mortality decreased after the improvement of the drinking water supply system through elimination of arsenic exposure from artesian well water. Standardized mortality ratios (SMRs) for bladder cancer were calculated for the BFD endemic area for the years 1971-2000. The study results show that mortality from bladder cancer declined gradually after the improvement of the drinking water supply system to eliminate arsenic exposure from artesian well water. Based on the reversibility criterion, this finding strengthened the likelihood of the observed association between arsenic exposure and bladder cancer being causal.",
Arsenic,1292192,"Rice consumption and urinary arsenic concentrations in U.S. Children Abstract: Background: In adult populations, emerging evidence indicates that humans are exposed to arsenic by ingestion of contaminated foods such as rice, grains, and juice; yet little is known about arsenic exposure among children.Objectives: Our goal was to determine whether rice consumption contributes to arsenic exposure in U.S. children.Methods: We used data from the nationally representative National Health and Nutrition Examination Survey (NHANES) to examine the relationship between rice consumption (measured in 0.25 cups of cooked rice per day) over a 24-hr period and subsequent urinary arsenic concentration among the 2,323 children (6-17 years of age) who participated in NHANES from 2003 to 2008. We examined total urinary arsenic (excluding arsenobetaine and arsenocholine) and dimethylarsinic acid (DMA) concentrations overall and by age group: 6-11 years and 12-17 years.Results: The median [interquartile range (IQR)] total urinary arsenic concentration among children who reported consuming rice was 8.9 ?g/L (IQR: 5.3-15.6) compared with 5.5 ?g/L (IQR: 3.1-8.4) among those who did not consume rice. After adjusting for potentially confounding factors, and restricting the study to participants who did not consume seafood in the preceding 24 hr, total urinary arsenic concentration increased 14.2% (95% confidence interval: 11.3, 17.1%) with each 0.25 cup increase in cooked rice consumption.Conclusions: Our study suggests that rice consumption is a potential source of arsenic exposure in U.S. children.",
Arsenic,2278522,"Different modes of adsorptions of arsenate on silica grafted with Fe3+-coordinated silanes Abstract: In order to optimize the adsorption of arsenate, we prepared silica based adsorbents by grafting Fe(3+)-coordinated N-(2-aminoethyl)-3-aminopropyltriethoxysilanes (aeaptes) in various Fe:aeaptes ratios (mixing ratios). Two kinds of mesoporous silica (MCM-41 and SBA-15) and fumed silica (Cab-O-sil M7D) were used as substrates. The adsorption of arsenate saturated at As/Fe=1, 2 and 3 on mesoporous silica based adsorbents from with Fe:aeaptes ratios of 1:1, 1:2 and 1:3, respectively. On the other hand, saturation occurred at As/Fe=1 on Cab-O-sil M7D-based adsorbents for all three Fe:aeaptes ratios. In addition to this dependence of the adsorption on the coordination conditions, two different modes were clearly distinguished in the adsorption isotherm for the MCM-41 based adsorbent prepared with a Fe:aeaptes ratio of 1:1. These two distinct adsorptions are likely to be due to the induction of well-defined coordination structures by this method. This result is significantly different from that found in a previous study where adsorbents were prepared by the grafting of aeaptes followed by the coordination of Fe(3+), where a single mode of adsorption was observed. The adsorptions were further analyzed using the Langmuir equation and by X-ray adsorption spectroscopy.",
Arsenic,2149313,"European Mineralogical Union Notes in Mineralogy: Environmental Mineralogy II Analytical, experimental and computational methods in environmental mineralogy Abstract: The analytical, experimental and computational methods now used in environmental mineralogy are introduced and illustrated with selected examples. Following a note on the importance of the radiation sources used for diffraction and spectroscopic studies, and a brief reminder of the key role still played by routine methods of mineral characterization (optical microscopy, X-ray powder diffraction [XRD], electron microbeam methods), more specialist techniques for the characterization of bulk solids (including nanoparticles) are considered. These include synchrotron-based advanced XRD and X-ray scattering methods, X-ray absorption spectroscopies, X-ray microprobe techniques, and infrared and Raman spectroscopies. Also considered are transmission electron microscopy, nuclear and magnetic spectroscopies, and particle induced X-ray emission. Following this, attention is focused on the characterization of mineral surfaces and interfaces using low-energy electron diffraction, X-ray reflectivity, X-ray absorption and X-ray standing wave methods, X-ray photoelectron and Auger electron spectroscopies, secondary ion mass spectrometry, environmental scanning electron microscopy, scanning tunnelling and atomic force microscopies and laser confocal microscopy. Computer modelling of solids, surfaces and solution species is discussed briefly before experimental approaches to determining reaction kinetics are considered, followed by experimental studies of the phenomena of adsorption, of evolution of the mineral surface during processes such as silicate weathering, and of how combinations of methods can be used to study the geochemical cycling of arsenic, olivine breakdown, or the comparative reactivities of silicate, carbonate, sulphide and oxide minerals.",
Arsenic,744849,"Global changes in posttranslational covalent histone modifications mediated by low-dose arsenic Abstract: In vitro, arsenic mediates induction of a large number of genes including the oxidative stress-response battery, a hallmark of arsenic exposure. In microarray experiments, arsenic also down-regulates at least as many genes as it induces, suggesting that arsenic triggers substantial alterations to chromatin structure through mechanisms that have yet to be elucidated. Gene promoter elements, when packaged as nucleosomes, exclude DNA-interacting proteins thereby preventing transcription, while active gene transcription necessitates relaxation of chromatin structure to permit protein access. Covalent modifications of promoter-region histones, spanning only a few nucleosomes, occur concomitantly with gene induction or repression. Here we investigate the global effects of low-dose arsenic treatment on covalent histone modifications. In general, acetylation relaxes histone structure permitting access of transcriptional proteins; conversely, deacetylation closes down chromatin structure, impairing transcription. Histones were isolated from human keratinocyte- derived HaCaT cells by acid extraction following exposure to 5 ?M arsenic. Reverse-phase high-pressure liquid chromatography (HPLC) was used to separate raw histone extracts into each major histone constituent, namely histones H2A, H2B, H3 and H4. Covalent modifications on each core histone were analyzed by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). In some instances, these modifications were confirmed using TAU-PAGE separation and immunoblot identification of specific modifications. The experiments presented here demonstrate that 1) at toxicologically relevant concentrations, arsenic modifies the pattern of covalent histone modification; 2) particular core histones are targets for arsenic-mediated covalent modification; 3) specific amino acid residues in each histone are targets for modification by arsenic.",
Arsenic,1381289,DETERMINATION OF AS CD AND PB IN FEEDSTUFF BY GRAPHITE FURNACE AAS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ENVIRONMENTAL TOXIN ARSENIC CADMIUM LEAD GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY ANALYTICAL METHOD,
Arsenic,2337094,"Iron and arsenic speciation in marine sediments undergoing a resuspension event: The impact of biotic activity Abstract: Purpose: Changes in the chemical conditions of sediment following a resuspension event might lead to release of sequestered pollutants. In the present study, arsenic (As) and iron (Fe) speciation were investigated before and after such an event, in sediment from L'Estaque marina (France). This marina is located near an industrial plant which processed As-bearing ores for several decades. Materials and methods: Cores (0–60 cm) and surface sediment (0–10 cm) were collected by a diver. Sediment properties along the length of the core were determined by coupling chemical extractions, and diffraction (i.e., X-ray diffraction) and spectroscopic techniques (i.e., micro-X-ray fluorescence, scanning electron microscopy coupled with energy dispersive spectroscopy, Raman spectroscopy, and X-ray absorption near-edge spectroscopy). Laboratory experiments mimicking resuspension and resettlement events were conducted over a period of 3 months in both biotic and abiotic (autoclaved) conditions. In both cases, oxidation proceeded by oxygen diffusion from the top to the bottom of the sediment. Results and discussion: It was demonstrated that the unperturbed sediment was anoxic. Arsenic, almost fully under its trivalent As(III) form, had a concentration between 194 and 473 ?g g?1, and its main carrier phase was the Fe-monosulfide mackinawite; this mineral originated from in situ transformation of Fe oxides, partly emitted by the industrial plant. The observed progressive pyritisation of mackinawite was not accompanied by further reduction of As which means that As remained bound to mackinawite, as incorporation into the pyrite lattice would require that it reduced to its (?I) oxidation state. After oxidation during the resuspension event, and in abiotic conditions, As was fully pentavalent As(V) in the oxidized zone of the re-settled sediment. On the contrary, in the biotic experiment, the development of a bacterial mat, which consumed oxygen for respiration processes, preserved the sediment from total oxidation. Consequently, As was present under both As(III) and As(V) forms, the first one being minor (?20 % of total As) in the top of the sediment. The diversity of aioA genes was large, and was similar in the oxidized layer and the deeper black-colored sediment. Conclusions: These results indicate that biological processes partly control the in situ geochemical system by inducing low redox areas in theoretically oxidized sediments.",
Arsenic,1519135,"Sheep psoroptic mange: An update on history, control and present situation in the United Kingdom Abstract: Psoroptic mange in sheep was first recognised in England with the dissolution of the monasteries by Henry VIII, as they yielded less wealth, due to erosion of their income by wool loss due to Psoroptic mange. The defining date in history of the disease is 1870, when owners and shepherds were obliged to report its presence in their flocks. Although in 1893, the first effective dips (arsenic, sulphur and nicotine) were introduced, during the 1890s, over 83,000 infested sheep were imported from America and Ireland, which led to an increase in prevalence of the disease. Hence, the government became involved and, in 1903, the problem was addressed with the introduction of the “Diseases of Animals Act”. Any sheep leaving a parish had to undergo dipping, organised by the local authority and the police. However, the measures failed and the disease was still rife in 1910. In 1914, the then Chief Veterinary Officer ordered that double dipping with an interval of eight days had to be carried out before the annual sheep sales. World War I resulted in lack of manpower and shrinking of the national flock, so by 1920 psoroptic mange had been reduced, except in the uplands and hill areas. In 1920, the local authorities of the country became empowered to make their own dipping arrangements and, as a result, chaos reigned. In 1933, another effort was made to address the problem in the uplands and hills, by involving the Ministry of Agriculture, the local authorities and the police. This was more effective and the prevalence of the disease was reduced, hence, in 1938, responsibility for control of the disease was transferred entirely to the Ministry of Agriculture. World War II brought the development of the organochlorine insecticides for incorporation into sheep dips. Following their use, prevalence of the disease decreased dramatically and the disease was eliminated by 1951. However, it was re-introduced to Great Britain by sheep imported from Ireland in 1973. Initially, cases were individually treated; then, in 1976, national dipping was introduced and, in 1983, double dipping became compulsory. In 1984, the organochlorines were withdrawn and for the next eight years the organophosphates held sway until introduction of the synthetic pyrethroids. The disease continued to occur, but at a fairly low prevalence. In 1988, the incidence fell to its lowest (only 16 cases), but, one year later, summer compulsory dip was abandoned and the possibility of eradicating the disease was lost. Finally, in 1992, psoroptic mange was deregulated, leading to increased incidence for the next three years to reach the rates of the late 1800s. Various half-hearted attempts were made to involve the industry through various schemes, but all have failed. Currently, the outlook to control, let alone eliminate, psoroptic mange looks bleak, except in Scotland where psoroptic mange is once again a notifiable disease. The early dips were partially successful in treating, but not eliminating psoroptic mange. Introduction of the organochlorines and organophosphates rectified the situation, but the disease had spread widely and problems of complete treatment and failure of some shepherds to take the problem seriously, failed to make full use of their efficacy. Macrocyclic lactones provide an easy control option, but they are not 100% effective, they have confusing directions for use and long withdrawal periods and they pose the danger of resistance development by internal parasites as a consequence of continuous use. Currently, the only available products with 100% efficacy are the organophosphates, which, however, are under threat, because of a perceived potential threat to humans; moreover, they have long withdrawal periods. Research studies into biological control and vaccination have not yielded any useful results. Hopefully, the return to notifiable disease status in Scotland will be successful and act as an incentive for a similar approach to be made in the rest of Great Britain.",
Arsenic,2345803,"Occurrence and distribution of selected heavy metals and boron in groundwater of the Gulf of Khambhat region, Gujarat, India Abstract: The concentration of selected heavy metals, like As, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn as well as B, was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) in groundwater samples from various locations in the Gulf of Khambhat (GoK), an inlet of the Arabian Sea in the state of Gujarat, India, during post-monsoon, winter, and pre-monsoon seasons in a year. Most heavy elements are characterized by low mobility under slightly alkaline and reducing conditions; concentrations in confined aquifers are smaller than the maximum permissible values for drinking water. The temporal changes indicate that a majority of metals is entering the aquifer during monsoon. Principle component analysis of the heavy metal data suggests that Co, Cu, Cd, and Zn are interrelated with each other and derived significantly from anthropogenic route, while input of Pb and Cr may be due to atmospheric deposition in the study area. Both weathering of rocks and anthropogenic input were found to be main sources of elements in the groundwater. The heavy metal levels in groundwaters of the GoK region in comparison with some of the European and Asian sites were higher; however, these metal levels were found to be comparable with few urban sites in the world.",
Arsenic,462298,"The influence of lead and arsenite on the inhibition of human breast cancer MCF-7 cell proliferation by American ginseng root (Panax quinquefolius L.) Abstract: American ginseng root (Panax quinquefolius) has a number of purported therapeutic effects, including inhibition of cancer cell proliferation. The ability of environmentally relevant heavy metals to alter ginseng effects on cancer cell growth was the subject of this study. A water extract of American ginseng root was applied alone or in combination with physiologically relevant doses of either lead (Pb) or arsenite to MCF-7 breast cancer cells in vitro and effects on cell proliferation were determined. Ginseng alone produced a significant dose-dependent inhibition of MCF-7 cell proliferation starting at 0.5 mg ml(-1). Treatment of MCF-7 cells with 2.5 mu M arsenite significantly decreased MCF-7 cell proliferation (p < 0.01). When cells were treated with arsenite (1.25 or 2.5 mu M) in combination with ginseng extract (0.5 mg ml(-1)), there was an apparent synergistic inhibition of cell proliferation. Treatment of MCF-7 breast cancer cells with 50 mu M Pb significantly decreased cell proliferation relative to control (p < 0.01), and concomitant ginseng and Pb treatment did not lead to a further decrease. These results suggest that contaminant heavy metals, some of which have been detected in ginseng root extracts or commercial ginseng preparations, may alter the biological activity of ginseng. (c) 2005 Elsevier Inc. All rights reserved.",
Arsenic,1509361,"Arsenic removal from aqueous solutions by Salvadora persica stem ash Abstract: Arsenic is a naturally occurring metalloid, which is widely distributed in nature and is regarded as the largest mass poisoning in history. In the present study, the adsorption potential of Salvadora persica (S. persica) stem ash in a batch system for the removal of As(V) from aqueous solutions was investigated. Isotherm studies were carried out to evaluate the effect of contact time (20–240?min), pH (2–11), initial arsenic concentration (50–500??g/L), and adsorbent dose on sorption efficiency. Maximum removal efficiency of 98.33% and 99.32% was obtained at pH 6, adsorbent dosage 3.5?g/L, initial As(V) concentration 500??g/L, and contact time 80 and 60?min for S. persica stem ash at 300?°C and 500?°C, respectively. Also, the adsorption equilibriums were analyzed by the Langmuir and Freundlich isotherm models. Such equilibriums showed that the adsorption data was well fitted with the Freundlich isotherm model for S. persica stem ash at both 300?°C and 500?°C ( and 0.9274, resp.). According to achieved results, it was defined that S. persica stem ash can be used effectively for As(V) removal from the aqueous environment.",
Arsenic,1519069,"Microwave ablation using 915-MHz and 2.45-GHz systems: what are the differences? Abstract: OBJECTIVES: This study was conducted to evaluate differences between 915-MHz and 2.45-GHz microwave ablation (MWA) systems in the ablation of hepatic tumours. METHODS: A retrospective analysis of patients undergoing hepatic tumour MWA utilizing two different systems over a 10-month period was carried out. RESULTS: Data for a total of 48 patients with a mean age of 58 ± 1.24 years were analysed. A total of 124 tumours were ablated; 72 tumours were ablated with a 915-MHz system and 52 with a 2.45-GHz system. Mean tumour diameters were 1.7 ± 0.1?cm in the 915-MHz group and 2.5 ± 0.2?cm in the 2.45-GHz group (P &lt; 0.01). Mean ablation time per burn was 8.1 ± 0.3?min in the 915-MHz group and 4.0 ± 0.1?min in the 2.45-GHz group (P &lt; 0.01). The mean number of burns per lesion was 2.0 ± 0.1 in the 915-MHz group and 1.7 ± 0.1 in the 2.45-GHz group (P &lt; 0.05). The mean ablation time per lesion was 9.7 ± 0.7?min in the 915-MHz group, and 6.6 ± 0.6?min in the 2.45-GHz group (P &lt; 0.01). The 2.45-GHz system demonstrated a better correlation between ablation time and tumour size (r(2) = 0.6222) than the 915-MHz system; (r(2) = 0.0696). Mean total energy applied per lesion, and energy applied per cm, were greater with the 915-MHz system (P &lt; 0.05 and P &lt; 0.01, respectively). Total energy applied per lesion was similarly correlated for the 2.45-GHz (r(2) = 0.6263) and 915-MHz (r(2) = 0.7012) systems. Mean total energy applied per cm/min was greater with the 2.45-GHz system (P &lt; 0.05). CONCLUSIONS: Both 915-MHz and 2.45-GHz MWA systems achieve reproducible hepatic tumour ablation. The 2.45-GHz system achieves equivalent, but more predictable and faster ablations using a single antenna system.",
Arsenic,627090,"Maternal arsenic exposure and impaired glucose tolerance during pregnancy Abstract: Background: Accumulating evidence has shown an increased risk of type 2 diabetes in general populations exposed to arsenic, but little is known about exposures during pregnancy and the association with gestational diabetes (GD). Objectives: We studied 532 women living proximate to the Tar Creek Superfund Site to investigate whether arsenic exposure is associated with impaired glucose tolerance during pregnancy. Methods: Blood glucose was measured between 24 and 28 weeks gestation after a 1-hr oral glucose tolerance test (GTT) as part of routine prenatal care. Blood and hair were collected at delivery and analyzed for arsenic using inductively coupled plasma mass spectrometry with dynamic reaction cell. Results: Arsenic concentrations ranged from 0.2 to 24.1 ?g/L (ppb) (mean ± SD, 1.7 ±1.5) and 1.1 to 724.4 ng/g (ppb) (mean ± SD, 27.4 ± 61.6) in blood and hair, respectively. One-hour glucose levels ranged from 40 to 284 mg/dL (mean ± SD, 108.7 ± 29.5); impaired glucose tolerance was observed in 11.9% of women when using standard screening criterion (> 140 mg/dL). Adjusting for age, Native-American race, prepregnancy body mass index, Medicaid use, and marital status, women in the highest quartile of blood arsenic exposure had 2.8 higher odds of impaired GTT than women in the lowest quartile of exposure (95% confidence interval, 1.1–6.9) (p-trend = 0.008). Conclusions: Among this population of pregnant women, arsenic exposure was associated with increased risk of impaired GTT at 24–28 weeks gestation and therefore may be associated with increased risk of GD.",
Arsenic,710915,"Effects of in utero arsenic exposure on child immunity and morbidity in rural Bangladesh Abstract: Chronic exposure to arsenic, a potent carcinogen and toxicant, via drinking water is a worldwide public health problem. Because little is known about early-life effects of arsenic on immunity, we evaluated the impact of in utero exposure on infant immune parameters and morbidity in a pilot study. Pregnant women were enrolled at 6-10 weeks of gestation in Matlab, a rural area of Bangladesh, extensively affected by arsenic contamination of tubewell water. Women (n=140) delivering at local clinics were included in the study. Anthropometry and morbidity data of the pregnant women and their children, as well as infant thymic size by sonography were collected. Maternal urine and breast milk were collected for immune marker and arsenic assessment. Maternal urinary arsenic during pregnancy showed significant negative correlation with interleukin-7 (IL-7) and lactoferrin (Ltf) in breast milk and child thymic index (TI). Urinary arsenic was also positively associated with fever and diarrhea during pregnancy and acute respiratory infections (ARI) in the infants. The effect of arsenic exposure on ARI was only evident in male children. The findings suggest that in utero arsenic exposure impaired child thymic development and enhanced morbidity, probably via immunosuppression. The effect seemed to be partially gender dependent. Arsenic exposure also affected breast milk content of trophic factors and maternal morbidity.",
Arsenic,1034587,"Health aspects of burning coal with a high arsenic content: II. Hearing changes in exposed children Abstract: HEEP COPYRIGHT: BIOL ABS. Hearing changes were analyzed after audiometric and clinical otorhinolaryngological examination of a group of 56 10 yr old children residing near a power plant burning local coal of high As content. The results of both audiometric and clinical examination were compared with those of a control group numbering 51 children of the same age living outside the polluted area. The highly standardized audiometric and clinical examinations were completed with a questionnaire analysis concerning the personal medical histories of the children. The data obtained were elaborated statistically by means of the chi2 text. In the case of air conduction, important hearing losses were found at frequencies of 125, 250 and 8000 Hz, especially at the lowest frequency range. Significant degrees of hearing loss were found in bone conduction as well as in the corresponding ranges of frequencies. The results of clinical examination including the vestibular one are discussed in detail. While an assumed influence of the anamnestic presence of middle ear inflammation is fully documented in the control group, such does not appear in the exposed group. The high statistical significance of the hearing impairments bound to points to a very low probability of their being only an accidental finding. The possibility of central damage to the ear cannot yet be excluded.",
Arsenic,1579256,"Seleniivibrio woodruffii gen. nov., sp. nov., a selenate- and arsenate-respiring bacterium in the Deferribacteraceae Abstract: The Gram negative, obligate anaerobic, selenate-respiring bacterium, strain S4T, was isolated from activated sludge of a wastewater treatment plant in New Jersey after enrichment with 10 mM selenate as the sole electron acceptor. In addition to its selenate respiring capability, strain S4T also respires arsenate with acetate as carbon source and electron donor. Fermentative growth was not observed. The optimum growth temperature was 37°C and optimum pH was 7. Phylogenetic analysis of the 16S rRNA gene revealed that strain S4T is a new member of the Deferribacteraceae family with Denitrovibrio acetiphilus as its closest cultivated relative with 91.5% sequence similarity. The cellular fatty acid content was composed of predominately straight-chain fatty acids, C14:0, C15:0, C16:0, C17:0, and C18:0, which distinguishes this organism from its closest relatives. The DNA G+C content was found to be 47.7 mol%. Together, these findings support that strain S4T represents a novel genus and species for which the name Seleniivibrio woodruffii gen. nov., sp. nov. is proposed. The Type strain is S4T = DSM 24984T = ATCC BAA-2290T.",
Arsenic,1018071,"Autophagy is the predominant process induced by arsenite in human lymphoblastoid cell lines Abstract: Arsenic is a widespread environmental toxicant with a diverse array of molecular targets and associated diseases, making the identification of the critical mechanisms and pathways of arsenic-induced cytotoxicity a challenge. In a variety of experimental models, over a range of arsenic exposure levels, apoptosis is a commonly identified arsenic-induced cytotoxic pathway. Human lymphoblastoid cell lines (LCL) have been used as a model system in arsenic toxicology for many years, but the exact mechanism of arsenic-induced cytotoxicity in LCL is still unknown. We investigated the cytotoxicity of sodium arsenite in LCL 18564 using a set of complementary markers for cell death pathways. Markers indicative of apoptosis (phosphatidylserine externalization, PARP cleavage, and sensitivity to caspase inhibition) were uniformly negative in arsenite exposed cells. Interestingly, electron microscopy, acidic vesicle fluorescence, and expression of LC3 in LCL 18564 identified autophagy as an arsenite-induced process that was associated with cytotoxicity. Autophagy, a cellular programmed response that is associated with both cellular stress adaptation as well as cell death appears to be the predominant process in LCL cytotoxicity induced by arsenite. It is unclear, however, whether LCL autophagy is an effector mechanism of arsenite cytotoxicity or alternatively a cellular compensatory mechanism. The ability of arsenite to induce autophagy in lymphoblastoid cell lines introduces a potentially novel mechanistic explanation of the well-characterized in vitro and in vivo toxicity of arsenic to lymphoid cells.",
Arsenic,627039,"Forced uptake of trivalent and pentavalent methylated and inorganic arsenic and its cyto-/genotoxicity in fibroblasts and hepatoma cells Abstract: Mammals are able to convert inorganic arsenic to mono-, di-, and trimethylated metabolites. In previous studies we have shown that the trivalent organoarsenic compounds are more toxic than their inorganic counterparts and that the toxicity is associated with the cellular uptake of the arsenicals. In the present study, we investigated cyto-/genotoxic effects of the arsenic compounds arsenate [As(i)(V)], arsenite [As(i)(III)], monomethylarsonic acid [MMA(V)], monomethylarsonous acid [MMA(III)], dimethylarsinic acid [DMA(V)], dimethylarsinous acid [DMA(III)], and trimethylarsine oxide [TMAO(V)] after an extended exposure time (24 h) and compared the uptake capabilities of fibroblasts (CHO-9 cells: Chinese hamster ovary) used for genotoxicity studies, with those of hepatic cells (Hep G2: hepatoma cell-line). To find out whether the arsenic compounds are bound to membranes or if they are present in the cytosol, the amount of arsenic was measured in whole-cell extracts and in membrane-removed cell extracts by inductively coupled plasma-mass spectrometry (ICP-MS). In addition, we forced the cellular uptake of the arsenic compounds into CHO-9 cells by electroporation and measured the intracellular arsenic concentrations before and after this procedure. Our results show that organic and inorganic arsenicals are taken up to a higher degree by fibroblasts compared to hepatoma cells. The arsenic metabolite DMA(III) was the most membrane permeable species in both cell lines and induced strong genotoxic effects in CHO-9 cells after an exposure time of 24 h. The uptake of all other arsenic species was relatively low (<1% by Hep G2 and <4% by CHO cells), but was dose-dependent. Electroporation increased the intracellular arsenic levels as well as the number of induced MN in CHO-9 cells. With the exception of As(i)(III) and DMA(III) in CHO-9 cells, the tested arsenic compounds were not bound to cell membranes, but were present in the cytosol. This may indicate the existence of DMA(III)-specific exporter proteins as are known for As(i)(III). Our results indicate that the uptake capabilities of arsenic compounds are highly dependent upon the cell type. It may be hypothesized that the arsenic-induced genotoxic effects observed in fibroblasts are due to the high uptake of arsenicals into this cell type. This may explain the high susceptibility of skin fibroblasts to arsenic exposure.",
Arsenic,1704138,Arsenic in soil and vegetation of a contaminated area Abstract: ,
Arsenic,2337178,"To add or not to add: The use of quenching agents for the analysis of disinfection by-products in water samples Abstract: The formation of disinfection by-products (DBPs) is a public health concern due to their potential adverse health effects. Robust and sensitive methods for the analysis of DBPs, as well as appropriate sample handling procedures, are essential to obtain accurate, precise and reliable data on DBP occurrence and formation. In particular, the use of an appropriate quenching agent is critical to prevent further formation of DBPs during the holding time between sample collection and analysis. Despite reports of decomposition of DBPs caused by some quenching agents, particularly sulphite and thiosulphate, a survey of the literature shows that they are still the most commonly used quenching agents in analysis of DBPs. This study investigated the effects of five quenching agents (sodium sulphite, sodium arsenite, sodium borohydride, ascorbic acid, and ammonium chloride) on the stability of seven different classes of DBPs commonly found in drinking waters, in order to determine the most appropriate quenching agent for the different classes of DBPs. All of the quenching agents tested did not adversely affect the concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs), and thus are suitable for quenching of disinfectant residual prior to analysis of these DBPs. Ascorbic acid was found to be suitable for the analysis of haloacetonitriles (HANs) and haloketones (HKs), but should not be used for the analysis of chlorite. Sodium arsenite, sodium borohydride, and ascorbic acid were all acceptable for the analysis of haloacetaldehydes (HALs). All of the quenching agents tested adversely affected the concentration of chloropicrin. A 'universal' quenching agent, suitable for all groups of DBPs studied, was not identified. However, based on the results of this study, we recommend the use of ascorbic acid for quenching of samples to be analysed for organic DBPs (i.e. THMs, HAAs, HANs, HKs, and HALs) and sodium sulphite for analysis of inorganic DBPs. Our study is the first comprehensive study on the effects of quenching agents on the stability of DBPs involving a wide range of DBP classes and quenching agents.",
Arsenic,1018957,"Microarray analysis of hepatotoxins in vitro reveals a correlation between gene expression profiles and mechanisms of toxicity Abstract: A rate-limiting step that occurs in the drug discovery process is toxicological evaluation of new compounds. New techniques that use small amounts of the experimental compound and provide a high degree of predictivity would greatly improve this process. The field of microarray technology, which allows one to monitor thousands of gene expression changes simultaneously, is rapidly advancing and is already being applied to numerous areas in toxicology. However, it remains to be determined if compounds with similar toxic mechanisms produce similar changes in transcriptional expression. In addition, it must be determined if gene expression changes caused by an agent in vitro would reflect those produced in vivo. In order to address these questions, we treated rat hepatocytes with 15 known hepatoxins (carbon tetrachloride, allyl alcohol, aroclor 1254, methotrexate, diquat, carbamazepine, methapyrilene, arsenic, diethylnitrosamine, monocrotaline, dimethyl-formamide, amiodarone, indomethacin, etoposide, and 3-methylcholanthrene) and used microarray technology to characterize the compounds based on gene expression changes. Our results showed that gene expressional profiles for compounds with similar toxic mechanisms indeed formed clusters, suggesting a similar effect on transcription. There was not complete identity, however, indicating that each compound produced a unique signature. These results show that large-scale analysis of gene expression using microarray technology has promise as a diagnostic tool for toxicology.",
Arsenic,1597418,"Assessment of the genotoxicity of two agricultural residues after processing by diplopods using the Allium cepa assay Abstract: Agroindustrial by-products and residues from treatment of sewage sludge have been recently recycled as soil amendments. This study was aimed at assessing toxic potential of biosolid, obtained from a sewage treatment plant (STP), vinasse, a by-product of the sugar cane industry, and a combination of both residues using Allium cepa assay. Bioprocessing of these samples by a terrestrial invertebrate (diplopod Rhinocricus padbergi) was also examined. Bioassay assembly followed standards of the Brazilian legislation for disposal of these residues. After adding residues, 20 diplopods were placed in each terrarium, where they remained for 30 days. Chemical analysis and the A. cepa assay were conducted before and after bioprocessing by diplopods. At the end of the bioassay, there was a decrease in arsenic and mercury. For the remaining metals, accumulation and/or bioavailability varied in all samples but suggested bioprocessing by animals. The A. cepa test revealed genotoxic effects characterized by different chromosome aberrations. Micronuclei and chromosome breaks on meristematic cells and F1 cells with micronuclei were examined to assess mutagenicity of samples. After 30 days, the genotoxic effects were significantly reduced in the soil?+?biosolid and soil?+?biosolid?+?vinasse groups as well as the mutagenic effects in the soil?+?biosolid?+?vinasse group. Similar to vermicomposting, bioprocessing of residues by diplopods can be a feasible alternative and used prior to application in crops to improve degraded soils and/or city dumps. Based on our findings, further studies are needed to adequately dispose of these residues in the environment.",
Arsenic,2345615,"Determination of doping and temperature-dependent elastic constants of degenerately doped silicon from MEMS resonators Abstract: Elastic constants c11, c12, and c44 of degenerately doped silicon are studied experimentally as a function of the doping level and temperature. First-and second-order temperature coefficients of the elastic constants are extracted from measured resonance frequencies of a set of MEMS resonators fabricated on seven different wafers doped with phosphorus (carrier concentrations 4.1, 4.7, and 7.5 x 10(19) cm(-3)), arsenic (1.7 and 2.5 x 10(19) cm(-3)), or boron (0.6 and 3 × 10(19) cm(-3)). Measurements cover a temperature range from -40°C to +85°C. It is found that the linear temperature coefficient of the shear elastic parameter c11 - c12 is zero at n-type doping level of n ~ 2 x 10(19) cm(-3), and that it increases to more than 40 ppm/K with increasing doping. This observation implies that the frequency of many types of resonance modes, including extensional bulk modes and flexural modes, can be temperature compensated to first order. The second-order temperature coefficient of c11 - c12 is found to decrease by 40% in magnitude when n-type doping is increased from 4.1 to 7.5 × 10(19) cm(-3). Results of this study enable calculation of the frequency drift of an arbitrary silicon resonator design with an accuracy of ±25 ppm between the calculated and real(ized) values over T = -40°C to +85°C at the doping levels covered in this work. Absolute frequency can be estimated with an accuracy of ±1000 ppm.",
Arsenic,2345644,"Household's willingness to pay for arsenic safe drinking water in Bangladesh Abstract: This study examines willingness to pay (WTP) in Bangladesh for arsenic (As) safe drinking water across different As-risk zones, applying a double bound discrete choice value elicitation approach. The study aims to provide a robust estimate of the benefits of As safe drinking water supply, which is compared to the results from a similar study published almost 10 years ago using a single bound estimation procedure. Tests show that the double bound valuation design does not suffer from anchoring or incentive incompatibility effects. Health risk awareness levels are high and households are willing to pay on average about 5 percent of their disposable average annual household income for As safe drinking water. Important factors influencing WTP include the bid amount to construct communal deep tubewell for As safe water supply, the risk zone where respondents live, household income, water consumption, awareness of water source contamination, whether household members are affected by As contamination, and whether they already take mitigation measures.",
Arsenic,2279227,"Effect of gemfibrozil, rifampicin, or probenecid on the pharmacokinetics of the SGLT2 inhibitor empagliflozin in healthy volunteers Abstract: <strong>BACKGROUND: </strong>Empagliflozin is a potent, oral, selective inhibitor of sodium glucose cotransporter 2 in development for the treatment of type 2 diabetes mellitus.<br /><br /><strong>OBJECTIVE: </strong>The goal of these studies was to investigate potential drug-drug interactions between empagliflozin and gemfibrozil (an organic anion-transporting polypeptide 1B1 [OATP1B1]/1B3 and organic anion transporter 3 [OAT3] inhibitor), rifampicin (an OATP1B1/1B3 inhibitor), or probenecid (an OAT3 and uridine diphosphate glucuronosyltransferase inhibitor).<br /><br /><strong>METHODS: </strong>Two open-label, randomized, crossover studies were undertaken in healthy subjects. In the first study, 18 subjects received the following in 1 of 2 randomized treatment sequences: a single dose of empagliflozin 25 mg alone and gemfibrozil 600 mg BID for 5 days with a single dose of empagliflozin 25 mg on the third day. In the second study, 18 subjects received a single dose of empagliflozin 10 mg, a single dose of empagliflozin 10 mg coadministered with a single dose of rifampicin 600 mg, and probenecid 500 mg BID for 4 days with a single dose of empagliflozin 10 mg on the second day in 1 of 6 randomized treatment sequences.<br /><br /><strong>RESULTS: </strong>In the gemfibrozil study, 11 subjects were male, mean age was 35.1years and mean body mass index (BMI) was 23.47kg/m(2). In the rifampicin/probenecid study, 10 subjects were male, mean age was 32.7years and mean BMI was 23.03kg/m(2). Exposure to empagliflozin was increased by coadministration with gemfibrozil (AUC0-?: geometric mean ratio [GMR], 158.50% [90% CI, 151.77-165.53]; Cmax: GMR, 115.00% [90% CI, 106.15-124.59]), rifampicin (AUC0-?: GMR, 135.20% [90% CI, 129.58-141.06]; Cmax: GMR, 175.14% [90% CI, 160.14-191.56]), and probenecid (AUC0-?: GMR, 153.47% [90% CI, 146.41-160.88]; Cmax: GMR, 125.60% [90% CI, 113.67-138.78]). All treatments were well tolerated.<br /><br /><strong>CONCLUSIONS: </strong>Increases in empagliflozin exposure were <2-fold, indicating that the inhibition of the OATP1B1/1B3, OAT3 transporter, and uridine diphosphate glucuronosyltransferases did not have a clinically relevant effect on empagliflozin exposure. No dose adjustments of empagliflozin were necessary when it was coadministered with gemfibrozil, rifampicin, or probenecid. ClinicalTrials.gov identifiers: NCT01301742 and NCT01634100.",
Arsenic,1022015,"Buffalo (Bubalus bubalis) epiphyseal proteins counteract arsenic-induced oxidative stress in brain, heart, and liver of female rats Abstract: Arsenic (As) toxicity through induction of oxidative stress is a well-known mechanism of organ toxicity. To address this problem, buffalo epiphyseal proteins (BEP, at 100 ?g/kg BW, i.p. for 28 days) were administered intraperitoneally to female Wistar rats exposed to As (100 ppm sodium arsenite via drinking water for 28 days). Arsenic exposure resulted in marked elevation in lipid peroxidation in brain, cardiac, and hepatic tissues, whereas significant (p?&lt;?0.05) adverse change in catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase, and reduced glutathione level were observed in cardiac, hepatic, and brain tissues of As-administered animals. BEP significantly (p?&lt;?0.05) counteracted all the adverse changes in antioxidant defense system brought about by As administration. Based on these results, we consider BEP as a potent antioxidant to be used for protection from arsenic-induced oxidative stress related damage of vital organs.",
Arsenic,627897,"A prospective study of blood selenium levels and the risk of arsenic-related premalignant skin lesions Abstract: Arsenic exposure from drinking water is considered to be a risk factor for skin and internal cancers. Animal studies suggest a potential antagonism between arsenic and selenium in the body. We did a case-cohort analysis to prospectively evaluate the association between arsenic-related premalignant skin lesions and prediagnostic blood selenium levels in 303 cases of skin lesions newly diagnosed from November 2002 to April 2004 and 849 subcohort members randomly selected from the 8,092 participants in the Health Effects of Arsenic Longitudinal Study with available baseline blood and urine samples collected in 2000. Incidence rate ratios for skin lesions in increasing blood selenium quintiles were 1.00 (reference), 0.68 [95% confidence interval (95% CI), 0.39-1.18], 0.51 (95% CI, 0.29-0.87), 0.52 (95% CI, 0.30-0.91), and 0.53 (95% CI, 0.31-0.90). Effect estimates remained similar with adjustments for age, sex, body mass index, smoking status, excessive sunlight exposure (in men), well water arsenic concentration at baseline, and nutritional intakes of folate, iron, protein, vitamin E, and B vitamins. At any given arsenic exposure level, the risk of premalignant skin lesions was consistently greater among participants with blood selenium lower than the average level. The findings support the hypothesis that dietary selenium intake may reduce the incidence of arsenic-related premalignant skin lesions among populations exposed to arsenic exposure from drinking water.",
Arsenic,627545,"Arsenic trioxide exposure to ovarian carcinoma cells leads to decreased level of topoisomerase II and cytotoxicity Abstract: The objective of this study was to investigate the effect of arsenic trioxide (As(2)O(3)) on topoisomerase II levels using western blotting method on MDAH 2774 ovarian carcinoma cell culture. Experimental designs were established to determine the cytotoxic effects of As(2)O(3) on MDAH 2774 cells and the IC50 (fatal dose for the 50% of cells) value. Cytotoxicity experiments were carried out using various concentrations of As(2)O(3). The 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) and trypan blue dye-exclusion tests were used to evaluate cytotoxicity. Topoisomerase II expressions were investigated using western blotting method with various concentrations of As(2)O(3). Densitometric analysis of topoisomerase 2 bands was carried out using Quantity One 1-D analysis software (Bio-Rad USA, Life Science Research, Hercules, CA). IC50 value of As(2)O(3) was found to be 5 x 10(-6) M for MDAH 2774 cells. When the bands were evaluated, it was observed that there was a decrease in topoisomerase II levels in MDAH 2774 cells with increasing concentrations of As(2)O(3). It was also observed by the densitometric analysis that topoisomerase II expression ratios of MDAH 2774 cells were decreased by approximately 50% at this concentration. Topoisomerase II levels were significantly decreased with the increasing concentrations of As(2)O(3). Inhibition of topoisomerase II enzyme was one of the antiproliferative influence mechanisms of As(2)O(3).",
Arsenic,2088540,"Herbal' but potentially hazardous: An analysis of the constituents and smoke emissions of tobacco-free waterpipe products and the air quality in the cafes where they are served Abstract: <strong>BACKGROUND: </strong>There are limited data on the composition and smoke emissions of 'herbal' shisha products and the air quality of establishments where they are smoked.<br /><br /><strong>METHODS: </strong>Three studies of 'herbal' shisha were conducted: (1) samples of 'herbal' shisha products were chemically analysed; (2) 'herbal' and tobacco shisha were burned in a waterpipe smoking machine and main and sidestream smoke analysed by standard methods and (3) the air quality of six waterpipe cafés was assessed by measurement of CO, particulate and nicotine vapour content.<br /><br /><strong>RESULTS: </strong>We found considerable variation in heavy metal content between the three products sampled, one being particularly high in lead, chromium, nickel and arsenic. A similar pattern emerged for polycyclic aromatic hydrocarbons. Smoke emission analyses indicated that toxic byproducts produced by the combustion of 'herbal' shisha were equivalent or greater than those produced by tobacco shisha. The results of our air quality assessment demonstrated that mean PM2.5 levels and CO content were significantly higher in waterpipe establishments compared to a casino where cigarette smoking was permitted. Nicotine vapour was detected in one of the waterpipe cafés.<br /><br /><strong>CONCLUSIONS: </strong>'Herbal' shisha products tested contained toxic trace metals and PAHs levels equivalent to, or in excess of, that found in cigarettes. Their mainstream and sidestream smoke emissions contained carcinogens equivalent to, or in excess of, those of tobacco products. The content of the air in the waterpipe cafés tested was potentially hazardous. These data, in aggregate, suggest that smoking 'herbal' shisha may well be dangerous to health.",
Arsenic,1247778,"Telmisartan treatment attenuates arsenic-induced hepatotoxicity in mice Abstract: The protective effect of telmisartan, the angiotensin II-receptor antagonist, against liver toxicity induced by sodium arsenite (5mg/kg/day, p.o., for 30 days) was investigated in mice. Telmisartan treatment (10mg/kg/day, p.o.) was applied for 30 days, starting on the same day of arsenic administration. Telmisartan significantly reduced serum alanine aminotransferase level which was increased by sodium arsenite. Telmisartan significantly suppressed lipid peroxidation, and prevented the reduced glutathione depletion and nitric oxide elevation in the liver tissue resulted from arsenic administration. Also, the increase of arsenic ion, and the reductions of selenium and zinc ions in liver tissue were attenuated by telmisartan. Histopathological examination showed that liver tissue injury mediated by arsenic was ameliorated by telmisartan treatment. Immunohistochemical analysis revealed that telmisartan significantly decreased the arsenic-induced expression of inducible nitric oxide synthase, tumor necrosis factor-?, cyclooxygenase-2, nuclear factor-?B and caspase-3 in liver tissue. It was concluded that telmisartan may represent a potential option to protect the liver tissue from the detrimental effects of arsenic toxicity.",
Arsenic,628069,"Interaction between environmental tobacco smoke and arsenic methylation ability on the risk of bladder cancer Abstract: OBJECTIVE: Arsenic exposure and environmental tobacco smoke (ETS) have been suspected to be associated with bladder cancer risk. We hypothesize that interaction between ETS and the ability to methylate arsenic, a detoxification pathway, modifies the risk of bladder cancer. METHODS: From January 1996 to December 1999, we identified 41 newly diagnosed bladder cancer patients and 202 fracture and cataract patients at the National Cheng-Kung University (NCKU) Medical Center. The levels of urinary arsenic species [As(III), As(V), MMA(V), and DMA(V)] were determined in all subjects. RESULTS: We found significant interaction between ETS and secondary methylation index (SMI) on the risk of bladder cancer (p=0.02). Among non-smokers with a high primary methylation index (PMI), the risk of bladder cancer was lower in subjects exposed to ETS (OR, 0.37; 95% CI, 0.14-0.96) than in subjects without exposure to ETS. Among non-smokers without ETS, the risk of bladder cancer was 4.7 times higher in subjects with a low SMI (95% CI, 1.30-16.81) than in subjects with a high SMI. CONCLUSIONS: Ability to methylate arsenic plays an important role in reducing the risk of bladder cancer attributable to the continuation of arsenic exposure from drinking water and from ETS exposure.",
Arsenic,2278887,"Spatial and temporal trends of metals and arsenic in German freshwater compartments Abstract: Cadmium, lead, mercury, copper, nickel, zinc, and arsenic were analyzed in suspended particulate matter (SPM), zebra mussels, and bream sampled yearly under the program of the German Environmental Specimen Bank (ESB) in the rivers Rhine, Elbe, Danube, Saar, Mulde, and Saale and in Lake Belau. Temporal and spatial trends were analyzed, correlations between metal levels in different specimen types assessed, and sampling sites ranked according to their metal levels by calculating a Multi-Metal Index (MMI) for every specimen type and site. SPM: Highest metal loads were detected in Mulde, Saale, and Elbe right downstream of the Saale confluence. In the Elbe, metal loads in SPM were mostly highest in the upper and middle section of the river while in Rhine and Saar concentrations increased downstream. Temporal trends since 2005 were detected only at three sites. Zebra mussel: MMIs were highest in the tidal section of the Elbe and the lower Rhine and lowest in Lake Belau and the upper Danube. Different temporal trends were detected since the early 1990s depending on site and metal. Bream: As, Pb, Cu, and Hg were analyzed in muscle tissue and Pb, Cd, Cu, and Zn in liver. For both tissues, MMIs were highest in Mulde and Saale and the lower and middle Elbe. Since the early 1990s, Hg, Pb, and Cu decreased in bream muscle at many sites while As increased at 6 of the 17 sites. The findings indicate that Hg, Pb, and Cu have obviously decreased in many freshwater ecosystems in recent years, whereas As and Ni levels have increased at several sites. Metal levels and temporal trends mostly differed between the specimen types under investigation and only few correlations between specimen types were detected. This underlines the importance of including different components of an ecosystem when assessing its environmental quality.",
Arsenic,2215699,"Arsenic programmes cellular genomic-immunity through miR-2909 RNomics Abstract: It is widely recognized that human cells are equipped with innate antiviral-RNA armour involving the production of type I interferons and APOBEC3G (apolipoprotein B mRNA-editing, enzyme-catalytic, polypeptide-like 3G) gene-product. Although arsenic has been shown to have paradoxical effect on one arm of this armour involving APOBEC3G, the exact molecular mechanism of its action in this regard is far from clear. The present study, addressed to explore as to how arsenic programmes this innate antiviral-RNA cellular-sensing pathway, clearly revealed that arsenic programmes this innate cellular antiviral genomic response through its inherent capacity to initiate cellular miR-2909 RNomics pathway, involving not only the modulation of APOBEC3G gene but also KLF4 (Kruppel-like factor 4) dependent regulation of gene coding for IKBK? (Inhibitor of nuclear factor kappa-B kinase subunit epsilon/gamma) which in turn modulates RIG-I (retinoic acid-inducible gene 1) pathway responsible for the production of IFN? (interferon beta) through restriction of CYLD (Cylindromatosis) deubiqutinating activity. This restricted inhibitory enzyme activity of CYLD upon NFkB (nuclear factor kappa-light-chain-enhancer of activated B cells) also ensures sustained expression of miR-2909. Our results for the first time show that cellular miR-2909 RNomics may constitute an innate genomic armour to promote as well as restrict retroviral infection.",
Arsenic,1346461,"Comparative hepatotoxicity and clastogenicity of sodium arsenite and three petroleum products in experimental Swiss Albino Mice: The modulatory effects of Aloe vera gel Abstract: Petroleum products (PPs) consist of complex chemical mixtures, mainly hydrocarbons. Their composition varies considerably with source and use. Inappropriate manual handling and use of PPs, in countries like Nigeria, results in excessive skin contact with the possibility of hazard to health. There has been inadequate evidence to classify diesel, kerosene and hydraulic oil as human carcinogens and there is limited evidence for their toxicity and carcinogenicity in experimental animals. We compared the hepatotoxicity and clastogenicity of diesel, petrol or hydraulic oil with that of sodium arsenite (Na(2)AsO(2)) in mice. Our findings showed that these PPs are capable of inducing gamma-glutamyl transferase (gammaGT) activity in the serum and liver to levels comparable with that induced by Na(2)AsO(2). Mice treated with individual PPs have elevated mean liver and serum gammaGT at levels that are significantly different from the values observed for the negative control group. Also, the individual PPs alone have micronuclei formation induction activity similar to Na(2)AsO(2). We found that treatment with Aloe vera gel before the PPs significantly reduced mean liver and serum gammaGT, and the mean number of micronuclei scored when compared with groups administered each of the PPs alone, supporting the presence of hepatoprotective components in Aloe vera.",
Arsenic,1373084,"Molecular Mechanisms Underlying Inhibition Of Insulin-Stimulated Glucose Uptake In Adipocytes Exposed To Trivalent Arsenicals Abstract: Chronic environmental or occupational exposures to inorganic arsenic (iAs) have been associated with increased prevalences of non-insulin-dependent (type-2) diabetes mellitus. The clinical symptoms of the disease indicate that iAs or its metabolites interfere with insulin signaling and/or suppress insulin-stimulated glucose metabolism in tissues. We have previously shown that exposures to subtoxic concentrations of arsenite (iAsIII), methylarsine oxide (MAsIIIO) or iododimethylarsine (DMAsIIII) inhibit glucose uptake in murine 3T3-L1 adipocytes by interfering with insulin-stimulated GLUT4 translocation from the perinuclear compartment to the plasma membrane. The present work examined molecular mechanisms underlying these effects. We found that treatments of cultured 3T3-L1 adipocytes with iAsIII or MAsIIIO resulted in suppression of insulin-dependent phosphorylation of protein kinase B (PKB/Akt) and inhibition of PKB/Akt activity. Neither iAsIII nor MAsIIIO interfered with activation of the components of the insulin-activated signal transduction pathway upstream from PKB/Akt. Notably, in an in vitro assay system, both arsenicals inhibited activity of PKB/Akt isolated by immunoprecipitation from untreated insulin-stimulated adipocytes. Unlike iAsIII and MAsIIIO, DMAsIIII did not suppress PKB/Akt phosphorylation or activity in intact adipocytes. However, DMAsIIII inhibited in vitro activity of the immunoprecipitated enzyme isolated from untreated cells. Expression of constitutively active PKB/Akt restored the normal pattern of insulin-dependent PKB/Akt phosphorylation and glucose uptake in cells treated with iAsIII or MAsIIIO, but had no effect on inhibition of glucose uptake in cells exposed to DMAsIIII. These results suggest that iAsIII and MAsIIIO interfere with insulin-stimulated glucose uptake in 3T3-L1 adipocytes by inhibiting PKB/Akt phosphorylation and the activity of the phosphorylated enzyme. The inhibition of glucose uptake by DMAsIIII may involve mechanisms independent of Akt.",
Arsenic,1936082,"Case-control study of arsenic in drinking water and lung cancer in California and Nevada Abstract: Millions of people are exposed to arsenic in drinking water, which at high concentrations is known to cause lung cancer in humans. At lower concentrations, the risks are unknown. We enrolled 196 lung cancer cases and 359 controls matched on age and gender from western Nevada and Kings County, California in 2002-2005. After adjusting for age, sex, education, smoking and occupational exposures, odds ratios for arsenic concentrations ?85 µg/L (median = 110 µg/L, mean = 173 µg/L, maximum = 1,460 µg/L) more than 40 years before enrollment were 1.39 (95% CI = 0.55-3.53) in all subjects and 1.61 (95% CI = 0.59-4.38) in smokers. Although odds ratios were greater than 1.0, these increases may have been due to chance given the small number of subjects exposed more than 40 years before enrollment. This study, designed before research in Chile suggested arsenic-related cancer latencies of 40 years or more, illustrates the enormous sample sizes needed to identify arsenic-related health effects in low-exposure countries with mobile populations like the U.S. Nonetheless, our findings suggest that concentrations near 100 µg/L are not associated with markedly high relative risks.",
Arsenic,2345721,"Comorbidity profile of chronic rhinosinusitis: A population-based study Abstract: OBJECTIVES/HYPOTHESIS: This study aimed to explore the prevalence of a broad spectrum of comorbid medical conditions among patients with chronic rhinosinusitis (CRS), using a population-based dataset. STUDY DESIGN: A cross-sectional study. METHODS: In total, 5,734 CRS subjects and 17,202 comparison subjects were included in this study. Separate conditional logistic regression analyses were performed to calculate the odds ratio (OR) for each of 39 medical comorbidities between subjects with and without CRS. RESULTS: For 27 of the 39 study comorbidities, results showed that subjects with CRS had a statistically significantly higher OR than subjects without CRS after adjusting for sociodemographic characteristics. Ranks of the top five comorbid relationships from the strongest ORs to the lowest were as follows: asthma (OR?=?3.09), chronic pulmonary disease (OR?=?3.04), weight loss (OR?=?2.58), obesity (OR?=?2.50), and migraines (OR?=?2.30). CONCLUSION: Our results indicate that subjects with CRS have an increased prevalence of various comorbidities.",
Arsenic,1936122,"Mid-Silurian back-arc spreading at the northeastern margin of Gondwana: The Dapingzhang dacite-hosted massive sulfide deposit, Lancangjiang zone, southwestern Yunnan, China Abstract: ",
Arsenic,2215767,"Low-cost field test kits for arsenic detection in water Abstract: Arsenic, a common contaminant of groundwater, affects human health adversely. According to the World Health Organization (WHO), the maximum recommended contamination level of arsenic in drinking water is 10 ?g/L. The purpose of this research was to develop user-friendly kits for detection of arsenic to measure at least up to 10 ?g/L in drinking water, so that a preventive measure could be taken. Two different kits for detection of total arsenic in water are reported here. First, the arsenic in drinking water was converted to arsine gas by a strong reducing agent. The arsine produced was then detected by paper strips via generation of color due to reaction with either mercuric bromide (KIT-1) or silver nitrate (KIT-2). These were previously immobilized on the detector strip. The first one gave a yellow color and the second one grey. Both of these kits could detect arsenic contamination within a range of 10 ?g/L-250 ?g/L. The detection time for both the kits was only 7 min. The kits exhibited excellent performance compared to other kits available in the market with respect to detection time, ease of operation, cost and could be easily handled by a layman. The field trials with these kits gave very satisfactory results. A study on interference revealed that these kits could be used in the presence of 24 common ions present in the arsenic contaminated water. Though the kits were meant for qualitative assay, the results with unknown concentrations of real samples, when compared with atomic absorption spectrophotometer (AAS) were in good agreement as revealed by the t-test.",
Arsenic,1797799,"Arsenic-tolerant, arsenite-oxidising bacterial strains in the contaminated soils of West Bengal, India Abstract: As biological agents represent an affordable alternative to costly metal decontamination technologies, we isolated arsenic (As) oxidising bacteria from the As-contaminated soils of West Bengal, India. These strains were closely related to various species of Bacillus and Geobacillus based on their 16S rRNA gene sequences. They were found to be hyper-resistant to both As(V) (167-400mM) and As(III) (16-47mM). Elevated rates of As(III) oxidation (278-1250?Mh(-1)) and arsenite oxidase activity (2.1-12.5nMmin(-1)mg(-1) protein) were observed in these isolates. Screening identified four strains as superior As-oxidisers. Among them, AMO-10 completely (100%) oxidised 30mM of As(III) within 24h. The presence of the aoxB gene was confirmed in the screened isolates. Phylogenetic tree construction based on the aoxB sequence revealed that two strains, AGO-S5 and AGH-02, clustered with Achromobacter and Variovorax, whereas the other two (AMO-10 and ADP-25) remained unclustered. The increased rate of As(III) oxidation by these native strains might be exploited for the remediation of As in contaminated environments. Notably, this study presents the first correlation regarding the presence of the aoxB gene and As(III) oxidation ability in Geobacillus stearothermophilus.",
Arsenic,627972,"Elevation of cellular BPDE uptake by human cells: a possible factor contributing to co-carcinogenicity by arsenite Abstract: BACKGROUND: Arsenite (iAsIII) can promote mutagenicity and carcinogenicity of other carcinogens. Considerable attention has focused on interference with DNA repair by inorganic arsenic, especially the nucleotide excision repair (NER) pathway, whereas less is known about the effect of arsenic on the induction of DNA damage by other agents. OBJECTIVES: We examined how arsenic modulates DNA damage by other chemicals. METHODS: We used an NER-deficient cell line to dissect DNA damage induction from DNA repair and to examine the effects of iAsIII on the formation of benzo[a]pyrene diol epoxide (BPDE)-DNA adducts. RESULTS: We found that pretreatment with iAsIII at subtoxic concentrations (10 microM) led to enhanced formation of BPDE-DNA adducts. Reduced glutathione levels, glutathione S-transferase activity and chromatin accessibility were also measured after iAsIII treatment, but none of these factors appeared to account for the enhanced formation of DNA adducts. However, we found that pretreatment with iAsIII increased the cellular uptake of BPDE in a dose-dependent manner. CONCLUSIONS: Our results suggest that iAsIII enhanced the formation of BPDE-DNA adducts by increasing the cellular uptake of BPDE. Therefore, the ability of arsenic to increase the bioavailability of other carcinogens may contribute to arsenic co-carcinogenicity.",
Arsenic,1020196,"Arsenic species excretion after controlled seafood consumption Abstract: Influence of controlled consumption of marine fish on the urinary excretion of arsenite, arsenate, dimethylarsinic and monomethylarsonic acid (DMA, MMA) was investigated in two experiments. Arsenic species were separated by anion-exchange chromatography and detected with hydride-technique atomic absorption spectrometry (detection limit 1, 10, 2, 2 microg/l). Firstly, 13 probands ate different types of seafood after having refrained from any seafood for 1 week. DMA levels rose from 3.4+/-1.3 microg/g creatinine (n=12; a day before seafood) to a mean peak level of 28.2+/-20.6 microg/g (n=13; 10-23 h after; P&lt;0.001; max. 77.7 microg/g). No other species were excreted before the meal, but small amounts of arsenite (8.5% positive; max. 1.7 microg/g) and MMA (1.2%; 1.6 microg/g) within 2 days after it (n=82). Consumption of white herring caused the highest DMA levels. Secondly, eight probands ingested white herring (dose 3.5 g/kg; DMA content 32.1+/-15.3 ng/g wet weight; n=36). No arsenite, arsenate and MMA was found in the urine or in the herring tissues. The mean DMA mass excreted after the meal (65.3+/-22.0 microg/24 h) was about 6-fold higher than the sum of base DMA excretion (3.0+/-1.7 microg/24 h) and the ingested DMA mass (7.9+/-2.7 microg). This indicates that the elevated DMA excretion after herring consumption is not caused by the metabolism of inorganic arsenic but of other arsenic species present in the fish tissue, e.g. arsenobetaine or fat-soluble arsenic species.",
Arsenic,1597398,"Bioaccessibility of 12 trace elements in marine molluscs Abstract: We conducted a large scale investigation of the bioaccessibility of 12 trace elements from 11 marine mollusc species (scallop, oyster, clam, abalone, snail, and mussel) collected from five locations in Chinese coastal waters. The bioaccessibility of all the 12 trace elements was generally high, with the average values ranging from 42.5% to 90.7%. The highest bioaccessibility was observed for As, Cu, Ni and Se, and the lowest for Fe, Co and Pb. Steaming decreased the bioaccessibility of all 12 trace elements and thus diminished their risks. No correlation was observed between the bioaccessibility and the total concentration of the 12 elements. However, there was a significant correlation between the bioaccessibility of the 12 elements and their subcellular distribution. For most trace elements, a significantly negative relationship was demonstrated between the bioaccessibility and the elemental partitioning in the metal-rich granule fraction or in the cellular debris fraction, and a significantly positive correlation was observed between the bioaccessibility and the elemental partitioning in the heat-stable protein fraction and in the trophically available fraction. Hence, the elemental subcellular distribution, especially the elemental partitioning in the trophically available fraction, might be a good predictor of the bioaccessibility and risks of trace elements in molluscs.",
Arsenic,710876,"The ATP-Binding Cassette Transporter ABCB6 Is Induced by Arsenic and Protects against Arsenic Cytotoxicity Abstract: Arsenic, an environmental carcinogen, remains a major public health problem. Arsenic damages biological systems through multiple mechanisms, including the generation of reactive oxygen species. ABCB6 is an ATP-binding cassette transporter that is highly expressed in cells resistant to arsenic. We have recently demonstrated that ABCB6 expression protects against cellular stressors. In the present study, we evaluated the significance of ABCB6 expression to arsenic toxicity both in mice and in cell culture. We show that sodium arsenite induces ABCB6 expression in a dose-dependent manner both in mice fed sodium arsenite in drinking water and in cells exposed to sodium arsenite in vitro. Arsenite-induced ABCB6 expression was transcriptionally regulated, but this induction was not mediated by the redox-sensitive transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2). We demonstrate that, in HepG2 and Hep3B cells, knockdown of ABCB6 expression using ABCB6-specific small interfering RNA sensitized the cells to arsenite toxicity. In contrast, stable overexpression of ABCB6 conferred a strong survival advantage toward arsenite-induced oxidative stress. Collectively, these results, obtained by both loss of function and gain of function analysis, suggest that ABCB6 expression in response to sodium arsenite might be an endogenous protective mechanism activated to protect cells against arsenite-induced oxidative stress.",
Arsenic,597993,"Inorganic cadmium- and arsenite-induced malignant transformation of human bladder urothelial cells Abstract: Arsenic and cadmium (Cd(+2)) are human carcinogens, and epidemiological studies have implicated both pollutants in the development of urinary bladder cancer. Despite this epidemiological base, it is unknown if either Cd(+2) or arsenite (As(+3)) can directly cause the malignant transformation of human urothelial cells. The goal of this study was to determine if Cd(+2) and/or As(+3) are able to cause the malignant transformation of human urothelial cells. The strategy employed was to expose the nontumorigenic urothelial cell line UROtsa to long-term in vitro exposure to Cd(+2) and As(+3), with the endpoint being the ability of the cells to form colonies in soft agar and tumors when heterotransplanted into nude mice. It was demonstrated that a long-term exposure to either 1 M Cd(+2) or 1 M As(+3) resulted in the selection of cells that were able to form colonies in soft agar and tumors when heterotransplanted into nude mice. The histology of the tumor heterotransplants produced by UROtsa cells malignantly transformed by Cd(+2) had epithelial features consistent with those of a classic transitional-cell carcinoma of the bladder. The histology of the tumor heterotransplants produced by cells malignantly transformed by As(+3) was unique in that the cells displayed a prominent squamoid differentiation.",
Arsenic,1018371,"DMPS-arsenic challenge test. I: Increased urinary excretion of monomethylarsonic acid in humans given dimercaptopropane sulfonate Abstract: The purpose of the present study was to evaluate in a novel manner the arsenic exposure of humans living in two towns in Northeastern Chile. Residents of one town drink water containing 593 microg As/l. Those in the control town drink water containing 21 microg As/l. Our hypothesis was that the administration of the chelating agent, 2,3-dimercaptopropane-1-sulfonic acid, Na salt (DMPS, DIMAVAL) would increase the urinary excretion of arsenic, alter the urinary profile of arsenic species and thus result in a better indication of the body load of arsenic and a better biomarker for arsenic exposure. The method used to evaluate these subjects was to give them 300 mg DMPS by mouth, after an overnight fast, and collect urine at specified time periods. The urine samples were analyzed for inorganic arsenic, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and total arsenic by hydride generation and atomic absorption spectrophotometry. The results indicated that: 1) During the 2-hr period after DMPS administration, MMA represented 42%, inorganic As, 20 to 22% and DMA, 37 to 38% of the total urinary arsenic. The usual range of the MMA percentage in human urine has been 10 to 20%. The % MMA increased almost equally for both the arsenic-exposed and control subjects. 2) The exposed subjects had a greater urinary excretion of total arsenic, before and after DMPS administration, than the control subjects. 3) Although buccal cells were obtained only from a few subjects, the prevalence of mononucleated buccal cells, an indication of genotoxicity, was 5-fold greater for those who consumed drinking water with the higher arsenic content than among control subjects. Our conclusions are that 1) DMPS has a highly specific effect in humans on MMA metabolism and/or urinary excretion; 2) the human body stores substantial amounts of arsenic; and 3) the urinary arsenic concentration after DMPS administration may be more indicative of the body burden of arsenic because it was greater than that found before DMPS was given.",
Arsenic,1936074,"Spontaneous Vitreous Hemorrhage in Children Abstract: <strong>PURPOSE: </strong>To determine the clinical profile, causes, and outcomes of &quot;spontaneous&quot; vitreous hemorrhage in children (&lt;18 years).<br /><br /><strong>DESIGN: </strong>Retrospective computer-assisted chart review.<br /><br /><strong>METHODS: </strong>Charts of 124 eyes of 76 children who presented with nontraumatic, nonsurgical vitreous hemorrhage between 2002 and 2012 were reviewed. All children underwent an appropriate ocular and systemic examination. Data collected included demographics, visual acuity, cause of &quot;spontaneous&quot; vitreous hemorrhage, ocular and systemic findings at presentation and at last follow-up, investigations, management details, and visual outcomes.<br /><br /><strong>RESULTS: </strong>The median age was 153.45 ± 56.19 months. There were 39 female and 37 male patients. Forty-eight patients had bilateral vitreous hemorrhage. The most common presenting complaints were diminished vision (96.45%) and behavioral changes (87.24%). The mean baseline BCVA in logMAR was 2.25 ± 1.11. The most common causes included vasculitis (34.6%) and hematologic disorders (27.4%). Patients were given medical therapy (topical and/or systemic) or underwent laser photocoagulation (29%) and/or surgery (55.6%). Twenty-nine eyes (23.3%) did not require any intervention. The mean number of surgeries was 1.89 ± 1.45 (range 1-4 surgeries). The mean final visual acuity was 0.76 ± 0.58 logMAR and was significantly better than the baseline (P &lt; .001). The best anatomic and visual outcomes were seen in vasculitis, whereas congenital disorders such as retinoschisis had the worst.<br /><br /><strong>CONCLUSIONS: </strong>Spontaneous pediatric vitreous hemorrhage has a diverse etiology, vasculitis being the most common cause in our series. A comprehensive evaluation (systemic and ocular) is required to ensure that vision- and life-threatening conditions are not missed.",
Arsenic,1326820,"Arsenite promotes centrosome abnormalities under a p53 compromised status induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) Abstract: Epidemiological evidence indicated that residents, especially cigarette smokers, in arseniasis areas had significantly higher lung cancer risk than those living in non-arseniasis areas. Thus an interaction between arsenite and cigarette smoking in lung carcinogenesis was suspected. In the present study, we investigated the interactions of a tobacco-specific carcinogen 4- (methylnitrosamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosamine ketone, NNK) and arsenite on lung cell transformation. BEAS-2B, an immortalized human lung epithelial cell line, was selected to test the centrosomal abnormalities and colony formation by NNK and arsenite. We found that NNK, alone, could enhance BEAS-2B cell growth at 1-5 microM. Under NNK exposure, arsenite was able to increase centrosomal abnormality as compared with NNK or arsenite treatment alone. NNK treatment could also reduce arsenite-induced G2/M cell cycle arrest and apoptosis, these cellular effects were found to be correlated with p53 dysfunction. Increased anchorage-independent growth (colony formation) of BEAS-2B cells cotreated with NNK and arsenite was also observed in soft agar. Our present investigation demonstrated that NNK could provide a p53 compromised status. Arsenite would act specifically on this p53 compromised status to induce centrosomal abnormality and colony formation. These findings provided strong evidence on the carcinogenic promotional role of arsenite under tobacco-specific carcinogen co-exposure.",
Arsenic,1070473,"Elemental concentrations in scalp hair, nutritional status and health-related quality of life in hemodialysis patients Abstract: Elemental concentrations in hair from hemodialysis (HD) patients have not been well investigated. We examined the relationships between the elemental concentrations in scalp hair and health-related quality of life (HRQOL) and nutritional status in HD patients. Twenty six elemental concentrations were measured in scalp hair samples from 60 male HD patients using inductively-coupled plasma mass spectrometry. To evaluate HRQOL, the Short Form 36 item health survey (SF36) was used. As indices of nutritional status, body mass index, serum parameters, and geriatric nutritional risk index (GNRI) were used. Phosphorus correlated positively with serum creatinine, blood urea nitrogen (BUN), GNRI and the physical domains of the SF36. Zinc correlated positively with serum creatinine, BUN and the physical domains of the SF36. Mercury and arsenic correlated positively with BUN. Cadmium correlated negatively with serum albumin, BUN and GNRI. Copper correlated positively with the physical domains of the SF36. Iodine correlated negatively with the physical domains of the SF36. Selenium correlated negatively with the mental domains of the SF36. In conclusion, phosphorus and zinc concentrations in scalp hair can be additional biomarkers of HRQOL and/or nutritional status in HD patients. Cadmium accumulation correlated with malnutrition. Iodine and selenium accumulation may adversely affect HRQOL. Further investigation is necessary to determine precisely how these elements affect these measures.",
Arsenic,2088492,"Methylated pentavalent arsenic metabolites are bifunctional inducers as they induce cytochrome P450 1A1 (CYP1A1) and NAD(P)H: quinone oxidoreductase (NQO1) through AhR and Nrf2 dependent mechanisms Abstract: Activation of the aryl hydrocarbon receptor (AhR) ultimately leads to the induction of the carcinogen activating enzyme cytochrome P450 1A1 (CYP1A1). While activation of the nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) in addition to the AhR pathway induces the expression of the NADP(H): quinone oxidoreductase (NQO1). Therefore, the aim of the current study was to examine the effect of As(III) pentavalent metabolites, MMA(V), DMA(V), and TMA(V) on AhR and Nrf2 activation and their prototypical downstream targets CYP1A1 and NQO1 expression, respectively. Our results showed that treatment of HepG2 cells with MMA(V), DMA(V), or TMA(V) in the absence and presence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or sulphoraphane (SUL) significantly induced both CYP1A1 and NQO1 at the mRNA, protein, and catalytic activity levels. Furthermore, these metabolites increased the AhR-dependent XRE-driven and the Nrf2-dependent ARE-driven luciferase reporter activities which coincided with increased nuclear accumulation of both transcription factors. However, none of these metabolites were shown to be AhR ligands. The induction of CYP1A1 by these metabolites appears to be ligand-independent possibly through decreasing HSP90 protein expression levels. The metabolites also increased ROS production that was significantly higher than that of As(III). Upon the knockdown of AhR and Nrf2 the MMA(V)-, DMA(V)-, and TMA(V)-mediated induction of both CYP1A1 and NQO1 proteins was significantly decreased. In conclusion, the present study demonstrates for the first time that methylated pentavalent arsenic metabolites are bifunctional inducers as they increase CYP1A1 through activating the AhR/XRE signaling pathway and they increase NQO1 through activating Nrf2/ARE signaling pathway in addition to the AhR/XRE pathway.",
Arsenic,1357248,"Arsenic Speciation in Serum of Uraemic Patients Based on Liquid Chromatography with Hydride Generation Atomic Absorption Spectrometry and On-Line UV Photo-oxidation Digestion Abstract: An on/line method for determining various arsenic (7440382) species in human serum was developed. The method was developed to determine monomethylarsonic-acid (124583) (MMA), dimethylarsinic-acid (75605) (DMA), arsenobetaine (37221333) (AsB), and arsenocholine (39895813) (AsC) by atomic absorption spectrometry using on line sample digestion. Serum samples were deproteinated with perchloric-acid, then digested on line by a photooxidation procedure using alkaline potassium-persulfate and ultraviolet irradiation, after which they were fractionated by cation exchange liquid chromatography. The eluents were analyzed for MMA, DMA, AsB, and AsC by hydride generation atomic absorption spectrometry. Recovery experiments in which human sera were spiked with 50 and 100 micrograms per liter (microg/l) MMA, DMA, AsB, and AsC yielded average recoveries of 98.3, 93.0, 95.4, and 94.7%, respectively. For a sample volume of 100 microliters, the detection limits for MMA, DMA, AsB, and AsC were 1.0, 1.3, 1.5, and 1.4microg/l, respectively. Ten replicate determinations of serum samples containing 10.0microg/l MMA, DMA, AsB, and AsC were associated with relative standard deviations varying from 4.2 to 4.8%. The method was applied to determining the arsenic species in serum samples from five uremic patients and one healthy person. AsB at concentrations of 1.90 to 9.10microg/l was detected in five samples and DMA at 1.15 and 2.60microg/l was detected in two samples from the uremic patients. AsC and MMA were not detected in any of the samples. No arsenic species were detected in the healthy subject. The authors conclude that the method is suitable for detecting MMA, DMA, AsB, and AsC in human serum.",
Arsenic,627615,"Case-control study of bladder cancer and arsenic in drinking water Abstract: Mortality from several cancers, including bladder cancer, is elevated in a Taiwanese population exposed to high levels of arsenic in drinking water. Data from the Utah respondents to the National Bladder Cancer Study conducted in 1978 were used to evaluate these associations in a US population exposed to measurable, but much lower, levels of drinking water arsenic. Two indices of cumulative arsenic exposure were used, one representing total cumulative exposure (index 1) and the other, intake concentration (index 2). Overall, there was no association of bladder cancer with either measure; however, among smokers, but not among nonsmokers, positive trends in risk were found for exposures estimated for decade-long time periods, especially in the 30- to 39-year period prior to diagnosis. Exposures were in the range 0.5-160 micrograms/liter (mean, 5.0 micrograms/liter). The data raise the possibility that smoking potentiates the effect of arsenic on risk of bladder cancer. However, the risk estimates obtained are much higher than predicted on the basis of the results of the Taiwanese studies, raising concerns about bias or the role of chance. Confirmatory studies are needed.",
Arsenic,1597378,"Atmospheric emissions of F, As, Se, Hg, and Sb from coal-fired power and heat generation in China Abstract: Coal is one of the major energy resources in China, with nearly half of produced Chinese coal used for power and heat generation. The large use of coal for power and heat generation in China may result in significant atmospheric emissions of toxic volatile trace elements (i.e. F, As, Se, Hg, and Sb). For the purpose of estimating the atmospheric emissions from coal-fired power and heat generation in China, a simple method based on coal consumption, concentration and emission factor of trace element was adopted to calculate the gaseous emissions of elements F, As, Se, Hg, and Sb. Results indicate that about 162161, 236, 637, 172, and 33 t F, As, Se, Hg, and Sb, respectively, were introduced into atmosphere from coal combustion by power and heat generation in China in 2009. The atmospheric emissions of F, As, Se, Hg, and Sb by power and heat generation increased from 2005 to 2009 with increasing coal consumptions.",
Arsenic,2347702,"Carfilzomib, cyclophosphamide, and dexamethasone in patients with newly diagnosed multiple myeloma: A multicenter, phase 2 study Abstract: This multicenter, open-label phase 2 trial determined the safety and efficacy of carfilzomib, a novel and irreversible proteasome inhibitor, in combination with cyclophosphamide and dexamethasone (CCyd) in patients with newly diagnosed multiple myeloma (NDMM) ?65 years of age or who were ineligible for autologous stem cell transplantation. Patients (N = 58) received CCyd for up to 9 28-day cycles, followed by maintenance with carfilzomib until progression or intolerance. After a median of 9 CCyd induction cycles (range 1-9), 95% of patients achieved at least a partial response, 71% achieved at least a very good partial response, 49% achieved at least a near complete response, and 20% achieved stringent complete response. After a median follow-up of 18 months, the 2-year progression-free survival and overall survival rates were 76% and 87%, respectively. The most frequent grade 3 to 5 toxicities were neutropenia (20%), anemia (11%), and cardiopulmonary adverse events (7%). Peripheral neuropathy was limited to grades 1 and 2 (9%). Fourteen percent of patients discontinued treatment because of adverse events, and 21% of patients required carfilzomib dose reductions. In summary, results showed high complete response rates and a good safety profile. This trial was registered at clinicaltrials.gov as #NCT01346787.",
Arsenic,2345937,"Urinary concentrations of bisphenol A and phthalate metabolites and weight change: a prospective investigation in US women Abstract: Objective:Both bisphenol A (BPA) and phthalates are known endocrine-disrupting chemicals for which there is widespread general population exposure. Human exposure occurs through dietary and non-dietary routes. Although animal studies have suggested a potential role of these chemicals in obesity, evidence from human studies is sparse and inconsistent, and prospective evidence is lacking. This study evaluated urinary concentrations of BPA and major phthalate metabolites in relation to prospective weight change.Methods:The study population was from the controls in a prospective case-control study of type 2 diabetes in the Nurses' Health Study (NHS) and NHSII. A total of 977 participants provided first-morning-void urine samples in 1996-2002. Urinary concentrations of BPA and nine phthalate metabolites were measured using liquid chromatography-mass spectrometry. Body weights were self-reported at baseline and updated biennially thereafter for 10 years.Results:On average, the women gained 2.09?kg (95% confidence interval (CI), -2.27 to 6.80?kg) during the 10-year follow-up. In multivariate analysis with adjustment of lifestyle and dietary factors, in comparison with women in the lowest quartile of BPA concentration, those in the highest quartile had 0.23?kg per year (95% CI, 0.07-0.38?kg per year) greater weight gain during the 10-year follow-up (P-trend=0.02). Several phthalate metabolites, including phthalic acid, MBzP and monobutyl phthalate, were also associated with faster prospective weight gain in a dose-response fashion (P-trend<0.01), whereas other phthalates metabolites, including MEP and monoethylhexyl phthalate, were not monotonically associated with body weight change.Conclusions:These data suggest urinary concentrations of BPA and certain individual phthalate metabolites that were associated with modestly greater weight gain in a dose-response fashion. These data are consistent with a potential role of BPA and phthalates in obesity, although more prospective data are needed to corroborate these observations.International Journal of Obesity advance online publication, 13 May 2014; doi:10.1038/ijo.2014.63.",
Arsenic,1347874,"c-fos induction by heat, arsenite, and cadmium is mediated by a heat shock element in its promoter Abstract: c-fos mRNA is induced by many types of noxious stimuli that are known to enhance transcription mediated by the heat shock element (HSE). Nonetheless, it has been accepted that the c-fos promoter does not contain an HSE. In this report, we revealed that the human and rodent c-fos promoters do contain HSEs which are highly responsive to heat, arsenite, and cadmium. These HSEs may play important roles in regulating c-fos expression in various pathological and physiological situations.",
Arsenic,2278556,"Arsenic and chromium removal from water using biochars derived from rice husk, organic solid wastes and sewage sludge Abstract: Biochars derived from rice husk, the organic fraction of municipal solid wastes and sewage sludge, as well as a sandy loam soil, were used as adsorbents for As(V), Cr(III) and Cr(VI) removal from aqueous solutions. The kinetic study showed that sorption can be well described by the pseudo-second order kinetic model, while simulation of sorption isotherms gave better fit for the Freundlich model. The materials examined removed more than 95% of the initial Cr(III). However, removal rates for As(V) and Cr(VI) anions were significantly lower. Biochar derived from sewage sludge was efficient in removing 89% of Cr(VI) and 53% of As(V). Its ash high Fe2O3 content may have enhanced metal adsorption via precipitation. Soil was the most effective material for the removal of As(V), yet it could not strongly retain metal anions compared to biochars, as a significant amount of the adsorbed metal was released during desorption experiments.",
Arsenic,1345701,"MORE EVIDENCE FOR A SELENIUM, ARSENIC INTERACTION IN MODIFYING MERCURY TOXICITY Abstract: HEEP COPYRIGHT: BIOL ABS.",
Arsenic,1070468,"Influence of amendments on soil arsenic fractionation and phytoavailability by Pteris vittata L Abstract: Increasing availability of soil arsenic is of significance for accelerating phytoremediation efficiency of As-polluted sites. The effects of seven amendments, i.e., citrate, oxalate, EDTA, sodium polyacrylate (SPA), phosphate rock (PR), single superphosphate (SSP), and compost on fractionation and phytoavailability of soil As were investigated in lab culture experiment. The results showed that the addition of PR, SPA, EDTA or compost to soils significantly increased the concentration of NaHCO(3)-extractable As over a 120d incubation period compared with the control (amendment-free) soil. Then, the four amendments were selected to add to As-contaminated soil growing Pteris vittata. It was concluded that As accumulation by the fern increased significantly under the treatments of PR and SPA by 25% and 31%, respectively. For As fractionation in soil, SPA increased Fe-As significantly by 51% and PR increased Ca-As significantly by 18%, while both the two amendments reduced occluded-As by 16% and 19%, respectively. Adding PR and SPA in soil increased the activities of urease and neutral phosphatase resulting from the improvement the fertility and physical structure of the soil, which benefits plant growth and As absorption of P. vittata. The results of the research revealed that both PR and SPA were effective amendments for improving phytoremediation of As-contaminated sites by P. vittata.",
Arsenic,1366182,"Coinduction of two low-molecular-weight stress proteins, alpha B crystallin and HSP28, by heat or arsenite stress in human glioma cells Abstract: The responses of two low-molecular-weight stress proteins, alpha B crystallin and HSP28, to various types of stress were determined quantitatively by specific immunoassays in a human glioblastoma cell line (U118 MG). Levels of alpha B crystallin (2-4 ng/mg protein) and HSP28 (1-1.5 micrograms/mg protein) in the soluble fraction from cells that had been cultured at 37 degrees C increased about 100-fold and 3-fold, respectively, within 24 h after heat treatment for 15 min at 45 degrees C, with a temporary decrease, due to redistribution to the insoluble fraction, during the heat treatment. Exposure of cells to arsenite (NaAsO2, 100 microM for 1 h) also induced the two proteins with a time course similar to that observed after heat stress, but without a decrease during the stress period. L-Azetidine-2-carboxylate (5 mM for 5 h) was also effective in inducing the two proteins, but to a lesser extent. Other chemicals, including CdCl2, ZnCl2, AlCl3, ethanol, caffeine, nicotine, NaN3, dibutyryl 3',5'-cyclic AMP, forskolin, and a phorbol ester, did not induce the two proteins. Expression of alpha B crystallin and HSP28 mRNAs in cells was enhanced after heat stress and after exposure to arsenite. When cells were challenged with heat stress in the presence of arsenite, the effect on the induction of the two proteins was synergistic. Ethanol (1-2%) enhanced the responses to heat stress or arsenite stress.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,2149114,"Potential beneficial uses of coalbed natural gas (CBNG) water Abstract: The CBNG well water is typically managed by discharging into nearby disposal ponds. The CBNG well water could potentially be very useful in the water-limited regions (e.g., arid and semi-arid), but beneficial uses may be hindered by water quality problems. Objectives of this research were to: (1) examine trend analysis of nine years of CBNG well water at discharge (outfall) points and in corresponding disposal ponds, (2) evaluate geochemical processes, (3) identify potential water quality issues, and (4) find potential beneficial uses. The CBNG well water at discharge points and in corresponding disposal ponds was measured on-site for pH and electrical conductivity (EC). These water samples were also analyzed in the laboratory for calcium (Ca), sodium (Na), magnesium (Mg), potassium (K), iron (Fe), aluminum (Al), copper (Cu), arsenic (As), selenium (Se), cadmium (Cd), and barium (Ba). Total dissolved solids (TDS) were calculated from EC measurements. The sodium adsorption ratio (SAR) was calculated from Na, Ca, and Mg concentrations. Trend analyses of outfalls and disposal ponds were conducted separately so that the differences in trends could be compared. Trends in CBNG well water at discharge points are not always the same as trends in CBNG disposal ponds: environmental and geochemical processes play an important role in the water quality of these well waters. Overall trend analyses suggest that CBNG well water at discharge points in all basins of the Powder River Basin meets beneficial use criteria, except for SAR and to some extent EC, for aquatic life, livestock and wildlife watering, and irrigation. The CBNG well water in disposal ponds across all basins meets criteria for all beneficial uses except for As, pH, SAR, and to some extent EC for irrigation, aquatic life, and livestock and wildlife watering.",
Arsenic,2149304,"THE EFFECT OF AN INTERVENTION WITH FISH AND SHELLFISH ON MERCURY, ARSENIC, LEAD, AND CADMIUM LEVELS IN BLOOD Abstract: ",
Arsenic,1797843,"Retinoic acid receptor alpha amplifications and retinoic acid sensitivity in breast cancers Abstract: BACKGROUND: Molecular segmentation of breast cancer allows identification of small groups of patients who present high sensitivity to targeted agents. A patient, with chemo- and trastuzumab-resistant HER2-overexpressing breast cancer, who presented concomitant acute promyelocytic leukemia, showed a response in her breast lesions to retinoic acid, arsenic, and aracytin. We therefore investigated whether RARA gene amplification could be associated with sensitivity to retinoic acid derivatives in breast cancers. MATERIALS AND METHODS: Array comparative genomic hybridization and gene expression arrays were used to characterize RARA amplifications and expression in 103 breast cancer samples. In vitro activity of ATRA was characterized in T47D, SKBR3, and BT474 cell lines. RESULTS: Retinoic acid receptor alpha was gained or amplified in 27% of HER2-positive and 13% of HER2-negative breast cancer samples. Retinoic acid receptor alpha can be coamplified with HER2. Retinoic acid receptor alpha copy number changes could be correlated with messenger RNA expression. All-trans-retinoic acid reduced cell viability of RARA-amplified, but not RARA-normal, cell lines through apoptosis. Gene expression arrays showed that ATRA-induced apoptosis in RARA-amplified cell lines was related to an increase in CASP1 and IRF1. CONCLUSION: The results of this study suggest that breast cancers exhibiting RARA amplifications could be sensitive to retinoic acid. A phase II trial will evaluate this hypothesis in the clinical setting.",
Arsenic,8464,"Mortality in a region surrounding an arsenic emitting plant Abstract: The purpose of the investigation is to study whether an increased mortality from certain causes exists in an area around the Rönnskärsverken smelter works in northern Sweden. Founded in 1928, this metallurgical plant processing mainly nonferrous metals has since its initial operations been using ore with a high arsenic content. This has resulted in environmental pollution to air and water of arsenic, as well as other metals and sulfur dioxide. The causes of death for the population of two parishes in the vicinity of the plant were listed from the National Sedish Register on Death Causes. A reference area in the same part of Sweden with similar degree of urbanization, occupational profile, and age distribution was chosen. The causes of death for the two populations were followed during a period of 14 yr. A significantly higher mortality rate for lung cancer was noted in men in the exposed area. However, this increase was no longer significant when the occupationally exposed at Rönnskärsverken were excluded. The latter showed a highly significant excess mortality due to primary respiratory cancer.A continuation of this investigation in the form of a cohort study of both the mortality and cancer incidence is currently under way.",
Arsenic,1352070,"Sources and behavior of arsenic and trace elements in groundwater and surface water in the Poopo Lake Basin, Bolivian Altiplano Abstract: ",
Arsenic,1015726,"Arsenic metabolism and thioarsenicals Abstract: Arsenic has received considerable attention in the world, since it can lead to a multitude of toxic effects and has been recognized as a human carcinogen causing cancers. Here, we focus on the current state of knowledge regarding the proposed mechanisms of arsenic biotransformation, with a little about cellular uptake, toxicity and clinical utilization of arsenicals. Since pentavalent methylated metabolites were found in animal urine after exposure to iAs(III), methylation was considered to be a detoxification process, but the discovery of methylated trivalent intermediates and thioarsenicals in urine has diverted the view and gained much interest regarding arsenic biotransformation. To further investigate the partially understood phenomena relating to arsenic toxicity and the uses of arsenic as a drug, it is important to elucidate the exact pathways involved in metabolism of this metalloid, as the toxicity and the clinical uses of arsenic can be best recognized in context of its biotransformation. Thereby, in this perspective, we have focused on arsenic metabolic pathways including three proposed mechanisms: a classic pathway by Challenger in 1945, followed by a new metabolic pathway proposed by Hayakawa in 2005 involving arsenic-glutathione complexes, while the third is a new reductive methylation pathway that is proposed by our group involving As-protein complexes. According to previous and present in vivo and in vitro experiments, we conclude that the methylation reaction takes place with simultaneous reductive rather than stepwise oxidative methylation. In addition, production of pentavalent methylated arsenic metabolites are suggested to be as the end product of metabolism, rather than intermediates.",
Arsenic,1346960,"Oxidative stress-induced alternative splicing of transformer 2beta (SFRS10) and CD44 pre-mRNAs in gastric epithelial cells Abstract: The tra2beta gene encoding an alternative splicing regulator, transformer 2-beta (Tra2beta), generates five alternative splice variant transcripts (tra2beta1-5). Functionally active, full-length Tra2beta is encoded by tra2beta1 isoform. Expression and physiological significance of the other isoforms, particularly tra2beta4, are not fully understood. Rat gastric mucosa constitutively expressed tra2beta1 isoform and specifically generated tra2beta4 isoform that includes premature termination codon-containing exon 2, when exposed to restraint and water immersion stress. Treatment of a gastric cancer cell line (AGS) with arsenite (100 microM) preferentially generated tra2beta4 isoform and caused translocation of Tra2beta from the nucleus to the cytoplasm in association with enhanced phosphorylation during the initial 4-6 h (acute phase). Following the acute phase, AGS cells continued upregulated tra2beta1 mRNA expression, and higher amounts of Tra2beta were reaccumulated in their nuclei. Treatment with small interference RNAs targeting up-frameshift-1 or transfection of a plasmid containing tra2beta1 cDNA did not induce tra2beta4 isoform expression and did not modify the arsenite-induced expression of this isoform, suggesting that neither the nonsense-mediated mRNA decay nor the autoregulatory control by excess amounts of Tra2beta participated in the tra2beta4 isoform generation. Knockdown of Tra2beta facilitated skipping of the central variable region of the CD44 gene and suppressed cell growth. In contrast, overexpression of Tra2beta stimulated combinatorial inclusion of multiple variable exons in the region and cell growth. The similar skipping and inclusion of the variable region were observed in arsenite-treated cells. Our results suggest that Tra2beta may regulate cellular oxidative response by changing alternative splicing of distinct genes including CD44.",
Arsenic,2278963,"Arsenic species uptake and subcellular distribution in Vallisneria natans (Lour.) Hara as influenced by aquatic pH Abstract: Vallisneria natans (Lour.) Hara, a widely distributed submerged aquatic plant, is a promising species for arsenic (As) removal from contaminated water. We investigated the effects of pH on the accumulation, subcellular distribution and detoxification of As in V. natans. The results showed that the optimum pH for submerged V. natans growth is close to 7.0. The accumulation of As in the plant increased with the increase of pH (p &lt; 0.05). This may have been due to arsenic/phosphate transporters with a higher affinity for the more highly electronegative AsO4 (3-) than for HAsO4 (2-) and H2AsO4 (-). After As(V) was accumulated by plants, more than 80 % was reduced to As(III), but As reduction decreased with increased pH. The majority of accumulated As and reduced As(III) (47 %-66 %) was found in the vacuoles. Higher As concentrations in vacuoles could be considered as an important mechanism for As detoxification in submerged plants.",
Arsenic,2345849,"A comparison of toxicant-induced succession for five antifouling compounds on marine periphyton in SWIFT microcosms Abstract: Five antifouling biocides, chlorothalonile, dichlofluanide, medetomidine, tolylfluanide, and zinc pyrithione, were evaluated regarding their effect on the composition of the periphyton community and the subsequent toxicant-induced succession (TIS). The periphyton communities were exposed in a semi-static setting for 96h using a SWIFT microcosm. As a measure of community composition, pigment profiles from the exposed communities were used as effect indicators and compared with unexposed parts of the same community using the Bray-Curtis dissimilarity index. Chlorothalonile caused changes in the community starting at 85 mu gl(-1) while dichlofluanide had no effect even at the highest concentrations used, 810 mu gl(-1). The related substance tolylfluanide only affected the community composition at 2700 mu gl(-1). Medetomidine had a different response curve with a small effect on the community composition at 0.8 mu gl(-1) which then disappeared only to reappear at 240 mu gl(-1). Zinc pyrithione had the largest effect on the periphyton community with changes starting at 10 mu gl(-1) and no detectable pigments at 100 mu gl(-1). The changes in the community composition for the five substances were also compared using multidimensional scaling. When all substances were analyzed and plotted together, chlorothalonile, dichlofluanide, medetomidine, and tolylfluanide showed surprisingly similar effects compared to zinc pyrithione that gave very different TIS. However, when only chlorothalonile, dichlofluanide, and tolylfluanide were plotted together, clear differences in TIS between the three toxicants were revealed. Dichlofluanide only induced small effects, while concentration-dependent TIS trajectories for chlorothalonile and tolylfluanide took off in opposite directions indicating very different responses of the periphyton communities. This study demonstrates that substances with a similar chemical structure and mechanisms of action can have different effects on the community composition. With the exception of zinc pyrithione, none of the recorded effect levels were at concentrations reported from marine environments so far.",
Arsenic,2149356,Geochemical evidences in the release processes of Arsenic into the groundwater in a part of Brahmaputra Floodplains Abstract: ,
Arsenic,1022117,"Urinary inorganic arsenic in residents living in close proximity to a nickel and copper smelter in Ontario, Canada Abstract: <strong>OBJECTIVES: </strong>The current study determines whether internal exposure to inorganic arsenic for residents living in close proximity to an operating smelter is any different from that for residents living in a similar community without anthropogenic sources of inorganic arsenic. Furthermore, the study examines factors that may contribute to internal inorganic arsenic exposure in these populations.<br /><br /><strong>METHODS: </strong>A cross-sectional study was used to determine whether recent internal exposure to inorganic arsenic for residents living in close proximity to an operating smelter with known elevated soil arsenic content is any different from exposure for residents living in a similar socio-demographic community without point sources of arsenic. Personal information was collected from participants during in-home interviews, and first morning void urine samples were obtained to assess recent internal exposure to arsenic.<br /><br /><strong>RESULTS: </strong>The mean concentration of urinary inorganic arsenic of residents living in the exposed community was 7.11 ug/L (Standard deviation (SD) 4.53, N = 368) and in the non-exposed community was 7.19 ug/L (SD 5.63, N = 321). The difference in urinary inorganic concentration was not statistically significant (p = 0.83). Regression analysis showed that age and sex were significant predictors of internal exposure, with males and younger age groups having higher exposure levels.<br /><br /><strong>CONCLUSIONS: </strong>Based on analyses of data collected, the results did not demonstrate a statistically significant difference in recent internal exposure to inorganic arsenic between the community with and the one without industrial or other point sources of environmental arsenic contamination. However, individual characteristics such as age and sex are important contributors to urinary inorganic arsenic levels.",
Arsenic,1346447,"Intracellular localization of the heat shock protein, HSP110, in Xenopus laevis A6 kidney epithelial cells Abstract: Heat shock protein 110 (HSP110) is a large molecular mass chaperone that is part of the HSP70/DnaK superfamily. In the present study, we examined the accumulation of HSP110 in Xenopus laevis A6 kidney epithelial cells. Immunoblot analysis, using a homologous antibody, detected the presence of HSP110 in A6 cells maintained at 22 degrees C. The relative levels of HSP110 accumulation increased after heat shock or sodium arsenite treatment. Immunocytochemical analysis revealed that constitutively expressed HSP110 was localized in the cytoplasm in a diffuse granular pattern with enrichment in the nucleus. In A6 cells heat shocked at 33 degrees C or 35 degrees C for 2 to 4 h, HSP110 accumulation was enhanced and detected primarily in the cytoplasm as thread- or spindle-like structures. In contrast, HSP30 was not detected constitutively and heat shock treatment of A6 cells induced a relatively uniform punctate pattern primarily in the cytoplasm. Also, treatment of A6 cells at 35 degrees C for 6 h resulted in the presence of HSP110 and HSP30 enriched in the nucleus of most cells. Finally, A6 cells treated with 25 microM sodium arsenite produced very dense HSP110 structures primarily in the cytoplasm while HSP30 was enriched in the cytoplasm in a granular pattern.",
Arsenic,62143,"Peripheral neuropathy in arsenic smelter workers Abstract: We conducted a double-blind controlled study of individuals exposed to arsenic trioxide in a copper-smelting factory. Subjects fell into three categories of peripheral neuropathy: none, subclinical, and clinical. The subclinical group had no symptoms or signs of numbness or reduced reflexes, but did have reduced nerve conduction velocity and amplitude measurements. Clinical neuropathy groups had signs and symptoms of neuropathy and electrophysiologic abnormalities. The clinical and subclinical groups correlated with increased content of arsenic in urine, hair and nails. The incidence of subclinical and clinical neuropathy was greater in arsenic workers than in unexposed controls.",
Arsenic,1240165,"Arsenic mobilization and speciation during iron plaque decomposition in a paddy soil Abstract: Purpose: Little information is available concerning the mobilization and speciation of arsenic (As) in paddy soils during iron plaque decomposition. It is important to investigate these processes since they affect As bioavailability and contaminate surface and ground water systems. Materials and methods: A microcosm experiment was conducted to investigate the reductive dissolution of iron plaque and subsequent As mobilization under NaN sub(3) sterilized (abiotic treatments) and non-sterilized (biotic treatments) paddy soil conditions. Results and discussion: In the biotic treatment, As and iron (Fe) were quickly released into the soil solution, with more than 76.1% of total arsenic (T sub(As)) on the roots lost in 27 days. In the abiotic treatment, both iron plaque decomposition and As release were significantly slower, with only 39.4% of T sub(As) on the roots lost in 85 days. A part of arsenate reduction reaction occurred before and may also occur after release from roots in both abiotic and biotic treatments. Bacterial abundance, quantified by real-time PCR, varied significantly between treatments. Terminal restriction fragment length polymorphism combined with principal component analysis (PCA) revealed that microbial community structures were also different between treatments. Conclusions: The changes in microbial factors (bacterial abundance and microbial diversity and activities) significantly affected iron plaque decomposition, As mobilization, and speciation processes. Iron plaque reductive dissolution was likely the major factor leading to As release. Most As released was trapped in the solid phase during the incubation period.",
Arsenic,499160,"Altered porphyrin excretion and histopathology of greylag geese (Anser anser) exposed to soil contaminated with lead and arsenic in the Guadalquivir Marshes, southwestern Spain Abstract: Greylag geese (Anser anser) in the Guadalquivir Marshes (southwestern Spain) can be exposed to sources of inorganic pollution such as heavy metals and arsenic from mining activities or Pb shot used for hunting. We have sampled 270 fecal excreta in different areas of the marshes in 2001 to 2002 to evaluate the exposure to Pb, Zn, Cu, Mn, and As and to determine its relationship with soil ingestion and with the excretion of porphyrins and biliverdin as biomarkers. These effects and the histopathology of liver, kidney, and pancreas were also studied in 50 geese shot in 2002 to 2004. None of the geese had ingested Pb shot in the gizzard. This contrasts with earlier samplings before the ban of Pb shot for waterfowl hunting in 2001 and the removal of Pb shot in points of the Donana National Park (Spain) in 1999 to 2000. The highest exposure through direct soil ingestion to Pb and other studied elements was observed in samples from Entremuros, the area of the Donana Natural Park affected by the Aznalcollar mine spill in 1998. Birds from Entremuros also more frequently showed mononuclear infiltrates in liver and kidney than birds from the unaffected areas, although other more specific lesions of Pb or Zn poisoning were not observed. The excretion of coproporphyrins, especially of the isomer 1, was positively related to the fecal As concentration, and the ratio of coproporphyrin III/I was positively related to fecal Pb concentration. Biliary protoporphyrin IX concentration was also slightly related to hepatic Pb concentration. This study reflects biological effects on terrestrial animals by the mining pollution in Donana that can be monitored with the simple noninvasive sampling of feces.",
Arsenic,2298747,"Antiplatelet and anticoagulation therapy in microlaryngeal surgery Abstract: OBJECTIVES/HYPOTHESIS: Indications for antiplatelet and anticoagulation use are expanding. There is no evidence to direct therapeutic management in patients undergoing microlaryngeal surgeries. Our aim was to compare bleeding complications between microlaryngeal surgeries performed for patients preoperatively taken off and maintained on antiplatelet and/or anticoagulation therapy. STUDY DESIGN: Retrospective cohort study. METHODS: Patients undergoing microlaryngeal surgeries (2008-2009) on baseline antiplatelet and/or anticoagulation therapy were identified. Records were reviewed to determine whether therapy was stopped preoperatively. The primary outcome, bleeding complication, was compared between those taken off and maintained on therapy. Patient characteristics, surgical data, and outcomes were assessed. RESULTS: Of 287 microlaryngeal surgeries, 26% were performed for patients on antiplatelet (23%) and/or anticoagulation (3%) therapy. There was no difference in bleeding complications between patients' naïve to and on baseline antiplatelet or anticoagulation therapy [naïve: 3.8% vs. on: 5.3%, P?=?0.58] and no thromboembolic events. Among surgeries performed for patients on baseline antiplatelet therapy, 35% preoperatively stopped therapy. No observed difference in bleeding complications was observed between those taken off or maintained on therapy [off: 8.0% vs. on: 4.9%, P?=?0.63]. Of 3% of surgeries performed for patients on warfarin, no bleeding complications occurred, even among the 8/10 with therapeutic international normalized ratios. CONCLUSIONS: Perioperative management decisions regarding antiplatelet and anticoagulation therapy are becoming more common. Results suggest that antiplatelet therapy can be maintained during microlaryngeal surgery without increasing bleeding risk. Further prospective research is required to confirm findings and rigorously investigate the safety of continuing warfarin and other anticoagulation therapy in these surgeries.",
Arsenic,2088303,"Metals and polybrominated diphenyl ethers leaching from electronic waste in simulated landfills Abstract: Landfills established prior to the recognition of potential impacts from the leaching of heavy metals and toxic organic compounds often lack appropriate barriers and pose significant risks of contamination of groundwater. In this study, bioavailable metal(oids) and polybrominated diphenyl ethers (PBDEs) in leachates from landfill columns that contained intact or broken e-waste were studied under conditions that simulate landfills in terms of waste components and methods of disposal of e-wastes, and with realistic rainfall. Fourteen elements and PBDEs were analysed in leachates over a period of 21 months. The results demonstrate that the average concentrations of Al, Ba, Be, Cd, Co, Cr, Cu, Ni, Pb, Sb and V in leachates from the column that contained broken e-waste items were significantly higher than the column without e-waste. BDE-153 was the highest average PBDEs congener in all columns but the average of ?PBDEs levels in columns that contained intact e-waste were (3.7 ng/l) and were not significantly higher than that in the leachates from the control column.",
Arsenic,2347696,"Arsenic uptake and depuration kinetics in Microcystis aeruginosa under different phosphate regimes Abstract: Strategies used by Microcystis aeruginosa, bloom-forming cyanobacteria, for potential inorganic arsenic (arsenate and arsenite) uptake, and depuration kinetics under phosphate-enriched (+P) and depleted (-P) treatments were examined via short- and long-term experiments. Phosphate depletion improved arsenate or arsenite uptake rate constants. M. aeruginosa arsenite influx occurred considerably faster than arsenate influx under +P or -P treatments. Different phosphate regimes yielded significant impacts on long-term but not on short-term arsenic (As) uptake. In addition, considerable differences were observed in short-term As efflux between live and dead cells after arsenate or arsenite pre-exposure. Arsenic depuration rates in live M. aeruginosa cells were affected not only by accumulation rates of different As inorganic species but also by phosphate concentrations in tested media, which was inferred from estimated kinetic parameters. Specifically, +P was clearly found to inhibit As efflux after live M. aeruginosa cells were pre-exposed to As(V). Efflux was higher for dead cells no matter the inorganic As species involved. Owing to higher As uptake and depuration rates under -P treatments, P deficiency will considerably accelerate As uptake and efflux processes in aquatic environments.",
Arsenic,1028819,"Expression of heme oxygenase in arsenic-resistant human lung adenocarcinoma cells Abstract: We have established arsenic-resistant cells (CL3R) and their subclones from a human lung adenocarcinoma cell line (CL3). CL3R cells and their subclones were maintained in the presence of 4 microM sodium arsenite. They were 6-fold more resistant than CL3 cells to arsenite. Heme oxygenase was expressed in CL3R cells and their subclones, as demonstrated by electrophoretic analysis, Northern blotting, and enzyme activity assay. When CL3R15 cells were grown in arsenite-free medium, their arsenite resistance declined in parallel with their decreasing heme oxygenase activity. Tin-protoporphyrin, a heme oxygenase inhibitor, was found to increase the toxicity of arsenic to CL3R cells. Expression of heme oxygenase might therefore be involved in the mechanism of arsenic resistance. CL3R cells were also shown to be cross-resistant to oxygen-radical generating agents, such as menadione and Adriamycin. Furthermore, sodium arsenite treatment dose-dependently increased the dichlorofluorescein fluorescence in CL3 cells but not in CL3R15 cells. These results suggest that heme oxygenase plays an important role in reducing cellular oxidants that are enhanced by sodium arsenite treatment.",
Arsenic,1247796,"Inorganic arsenic impairs proliferation and cytokine expression in human primary T lymphocytes Abstract: Inorganic arsenic is a toxic environmental contaminant to which humans are mainly exposed through drinking water. This metalloid impairs functions of several key immune cells. Particularly, it reduces IL-2 secretion and proliferation of blood peripheral mononuclear cells stimulated by lectins that, however, do not mimic physiological T cell activation. The present study used isolated human T cells activated, in a more physiological manner, through stimulation with CD3/CD28 antibodies, to carefully analyze the impact of arsenic on T cell proliferation and cytokine expression. We demonstrate that non cytotoxic concentrations of sodium arsenite (As(III), 0.25-2?M) significantly reduce T cell proliferation by increasing the percentage of non dividing cells blocked in G1 phase and by preventing cyclin D3 and CDC25A expression. They also markedly, although not totally, reduces IL-2 expression at both mRNA and protein levels; however, metalloid-dependent inhibition of T cells could not be reversed by addition of recombinant IL-2. In addition, As(III) markedly reduces secretion of interferon-? without impairing that of IL-4 and IL-13; it also decreases interferon-? mRNA levels but increases those of IL-13. Finally, simultaneously to its immune effects, As(III) rapidly and potently increases expression of the redox-sensitive genes HMOX1, NQO1 and GCLM in activated T cells without altering the levels of reactive oxygen species. In conclusion, our results demonstrate that As(III) inhibits T cell proliferation, independently of IL-2, and alters the Th balance of cytokines secreted by co-stimulated T cells which thus constitute direct targets of this major environmental contaminant.",
Arsenic,1070457,"Zinc in well water and infant mortality in Bangladesh: A report from Gonoshasthaya Kendra Abstract: Zinc supplementation reduces the duration, severity and recurrence of diarrhoea in young children. This study examines whether zinc, found naturally in drinking water, reduced infant deaths from diarrhoea in rural Bangladesh. Information was compiled for births over two calendar years with follow-up for deaths within one year of birth. The study included 29,744 live births and 934 deaths in some 600 villages under the care of Gonoshasthaya Kendra (GK), grouped into 15 health centre regions within 12 upazillas. Individual matching of death to birth data was not possible, but information on exposures through well water and on potential confounders was available for each upazilla. Average concentration of zinc in well water, reported by the British Geological Survey, was grouped into high (>0.07 mg/L), moderate (0.020-0.070 mg/L) and low (&lt;0.020 mg/L) concentrations. Odds ratios (OR) were calculated for zinc by age and cause of death. Zinc concentration was unrelated to all-cause mortality but a decrease in deaths from diarrhoea (N = 50) was seen in areas with high zinc (OR = 0.30; 95% CI 0.13-0.69). No relation to diarrhoeal deaths was found with other well contaminants (arsenic, manganese) having accounted for zinc. Upazillas with a high proportion of women without education had higher rates of death from diarrhea, but the decrease in risk with high zinc remained (OR adjusted = 0.41; 95% CI 0.20-0.84). It is concluded that exposure to zinc through drinking water may reduce risk of diarrhoeal deaths.",
Arsenic,1340110,"Developmental and neurobehavioural toxicity study of arsenic on rats following gestational exposure Abstract: To characterize developmental and behavioral alterations induced by arsenic exposure, Albino rats were exposed to arsenic (0, 1.5, 3.0 and 4.5 mg/kg/day/po) from gestation day 8 to till parturition and the offspring were observed over the first 3 postnatal weeks, until they were weaned on post-natal day (PND) 21. Once the pups were delivered (PND0), the treatment was discontinued. All pups were assessed for physical development, reflex development, strength and motor coordination from standard neurobehavioural developmental test batteries beginning on PND1. Gestational administration of arsenic at tested dose levels, showed no significant changes in the day of appearance of eye opening, startle reflex, negative geotaxis and spontaneous alteration performance in comparison to the control group. The number of live fetuses, mean fetal body weight and percentages of resorptions or malformations per litter were not affected by arsenic exposure. No treatment-related malformations or developmental variations were noted at any exposure level, suggesting that arsenic exposure at this dose level did not adversely affect behavioural endpoints of developmental toxicity.",
Arsenic,62165,"Chromosomal aberrations and fetotoxic effects of atmospheric arsenic exposure in mice Abstract: Fetal chromosomal damage and toxicity were investigated in mice exposed to the atmospheric concentrations of 28.5 mg m-3, 2.9 mg m-3 and 0.26 mg m-3 of arsenic for 4 h per day on the 9th, 10th, 11th and 12th days of gestation. On the 18th day, the fetuses were removed, and the following parameters were examined: the number of dead fetuses, retardation in growth, osteogenesis and chromosomal aberrations in liver cells. It was found that exposure to As2O3 at 28.5 mg m-3 caused fetotoxic effects and chromosomal damage, while the two lower exposures produced no significant changes with the exception of a slight decrease (9.9 and 3.1%, respectively) in fetal weight.",
Arsenic,1015672,"Associations between microRNA (miR-21, 126, 155 and 221), albuminuria and heavy metals in Hong Kong Chinese adolescents Abstract: BACKGROUND AND AIM: Pathogenetic mechanisms underlying albuminuria are not completely understood. Heavy metals might lead to atherosclerosis and kidney damage. miR-21, 126, 155 and 221 regulated endothelial function and might contribute to the development of albuminuria. To date, no clinical trial has explored the relationship between miRNAs, microalbuminuria and heavy metals in human. In this study, we aimed to examine the association between microalbuminuria, miRNAs and heavy metals in adolescents. MATERIALS AND METHODS: From a cross-sectional, population-recruited study, we identified 60 school children aged 12-19years with microalbuminuria (defined as spot urine albumin-creatinine ratio &gt;3.5mg/mmol). We compared the urine heavy metals (arsenic, mercury, cadmium and lead) and miRNAs levels (miR-21,126, 155 and 221) with another 60 age-and sex-matched normoalbuminuric adolescents as control. RESULTS: Mean age of the study cohort was 15.5±2.1years. 43% were boys. Among the four miRNAs tested, only miR-21 was associated with microalbuminuria (p=0.02). Urinary arsenic and lead levels had a negative association with both miR-21 and miR-221. No significant association was found between heavy metals examined and microalbuminuria. CONCLUSION: The results of our study suggest an association between microalbuminuria, miR-21 and heavy metals (arsenic and lead). This might imply that miR-21 is involved in the pathogenetic mechanisms linking heavy metals exposure and albuminuria.",
Arsenic,1508721,"Towards better triage of infants suspected of cow's milk allergy: development of a preliminary multivariable diagnostic index Abstract: The double-blind placebo-controlled food challenge (DBPCFC) is currently the gold standard to diagnose cow's milk allergy (CMA). However, DBPCFCs are burdensome, expensive and require specialised facilities. For primary care physicians, selective and consistent referral to DBPCFC of infants suspected of CMA may be difficult. The objective of this study was to assess the predictive value of clinical parameters for a positive DBPCFC in infants suspected of CMA. Clinical data from 124 infants suspected of CMA that had undergone a DBPCFC were collected. Out of a total of 23 parameters, nine candidate predictors were selected on clinical grounds. We used bootstrapped logistic regression analysis to find a more parsimonious and practical model. The prevalence of a positive DBPCFC was 34.7 % (95 % CI from 27 to 43). A well-calibrated diagnostic model containing as predictors abdominal cramps, inconsolable crying and the objective SCORAD index discriminated moderately well between infants with and without a positive DBPCFC. The area under the ROC curve was 0.68 (95 % CI from 0.58 to 0.78). The fifth and 95th percentiles of the positive DBPCFC predictive probability distribution were 17 and 73 % (17 and 59 % after correction for over-optimism). We conclude that a diagnostic model with three clinical parameters may be used for better referral of children suspected of CMA and the decision to either initially perform an open food challenge or directly perform a DBPCFC. Large prospective studies are needed to validate these findings and provide additional precision.",
Arsenic,471138,"Arsenic moiety in gallium arsenide is responsible for neuronal apoptosis and behavioral alterations in rats Abstract: Gallium arsenide (GaAs), an intermetallic semiconductor finds widespread applications in high frequency microwave and millimeter wave, and ultra fast supercomputers. Extensive use of GaAs has led to increased exposure to humans working in semiconductor industry. GaAs has the ability to dissociate into its constitutive moieties at physiological pH and might be responsible for the oxidative stress. The present study was aimed at evaluating, the principle moiety (Ga or As) in GaAs to cause neurological dysfunction based on its ability to cause apoptosis, in vivo and in vitro and if this neuronal dysfunction translated to neurobehavioral changes in chronically exposed rats. Result indicated that arsenic moiety in GaAs was mainly responsible for causing oxidative stress via increased reactive oxygen species (ROS) and nitric oxide (NO) generation, both in vitro and in vivo. Increased ROS further caused apoptosis via mitochondrial driven pathway. Effects of oxidative stress were also confirmed based on alterations in antioxidant enzymes, GPx, GST and SOD in rat brain. We noted that ROS induced oxidative stress caused changes in the brain neurotransmitter levels, Acetylcholinesterase and nitric oxide synthase, leading to loss of memory and learning in rats. The study demonstrates for the first time that the slow release of arsenic moiety from GaAs is mainly responsible for oxidative stress induced apoptosis in neuronal cells Causing behavioral changes. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,2337162,"A HYBRID SYSTEM INCORPORATING A PIPE REACTOR AND MICROFILTRATION FOR BIOLOGICAL IRON, MANGANESE AND ARSENIC REMOVAL FROM ANAEROBIC GROUNDWATER Abstract: In the present work the removal of As(III) and As(V) from groundwater was studied by the application of biological oxidation of dissolved iron and manganese in a pipe reactor (PR), followed by microfiltration (MF). The examined groundwater (Berlin, Marienfelde) contained average Fe(III) and Mn(II) concentrations of 2.9 and 0.6 mg/L, respectively. Oxidation of these metals provided sufficient adsorption sites and therefore, arsenic species were removed from groundwater very efficiently. From initial arsenic concentrations in the range 20 to 250 mu g/L, the residual concentrations were in all cases below 10 mu g/L. A significant advantage of this technology is the uptake of oxidized iron and manganese onto recirculated suspended solids which flocculated in the pipe reactor, thus eliminating the need for mechanical cleaning of the membrane, while keeping the Trans-Membrane Pressure (TMP) constantly low. Furthermore, the As(V) removal capacity in terms of mu g As(V) removed per mg of this hybrid PR-MF unit was found to be significantly higher than that achieved by conventional coagulation filtration with Fe(III). The presence of phosphate at concentrations up to 1.6 mg/L did not exercise any negative impact on As(III) removal from initial As(III) concentrations of 100 mu g/L. Conclusively, the proposed PR-MF process efficiently removes iron, manganese and arsenic without the use of chemical reagents for oxidation or pH adjustment, and without the need for regular regeneration or backwashing, and thus it follows the principles of green chemistry.",
Arsenic,1508551,"Arsenic mobility controlled by solid calcium arsenates: A case study in Mexico showcasing a potentially widespread environmental problem Abstract: An As-contaminated perched aquifer under an urban area affected by mining was studied over a year to determine the contamination source species and the mechanism of As mobilization. Results show that the dissolution of calcium arsenates in residues disposed on an inactive smelter has caused high levels of As pollution in the adjoining downgradient 6-km perched aquifer, reaching up to 158 mg/L of dissolved As, and releasing a total of ca. 7.5 tons of As in a year. Furthermore, free calcium ion availability was found to control As mobility in the aquifer through the diagenetic precipitation of calcium arsenates (Ca(5)H(2)(AsO(4))(4)·cH(2)O) preventing further mobilization of As. Results shown here represent a model for understanding a highly underreported mechanism of retention of arsenate species likely to dominate in calcium-rich environments, such as those in calcareous sediments and soils, where the commonly reported mechanism of adsorption to iron(III) oxyhydroxides is not the dominant process.",
Arsenic,710966,"Inorganic arsenite inhibits IgE receptor-mediated degranulation of mast cells Abstract: Millions of people worldwide are exposed to arsenic (As), a toxicant which increases the risk of various cancers, cardiovascular disease and several other health problems. Arsenic is a potent endocrine disruptor, including of the estrogen receptor. It was recently shown that environmental estrogen-receptor disruptors can affect the signaling of mast cells, which are important players in parasite defense, asthma and allergy. Antigen (Ag) or allergen crosslinking of IgE-bound receptors on mast cells leads to signaling, culminating in degranulation, the release of histamine and other mediators. Because As is an endocrine disruptor and because endocrine disruptors have been found to affect degranulation, here we have tested whether sodium arsenite affects degranulation. Using the rat basophilic leukemia (RBL) mast cell model, we have measured degranulation in a fluorescence assay. Arsenic alone had no effect on basal levels of degranulation. However, As strongly inhibited Ag-stimulated degranulation at environmentally relevant concentrations, in a manner that is very dependent on concentrations of both As and Ag. The concentrations of As effective at inhibiting degranulation were not cytotoxic. This inhibition may be a mechanism underlying the traditional Chinese medicinal use of As to treat asthma. These data indicate that As may inhibit the ability of humans to fight off parasitic disease. Copyright © 2010 John Wiley &amp; Sons, Ltd.",
Arsenic,2279273,"Myxococcus xanthus low-molecular-weight protein tyrosine phosphatase homolog, ArsA, possesses arsenate reductase activity Abstract: Myxococcus xanthus MXAN_0575, ArsA, exhibited sequence homology to low-molecular-weight protein tyrosine phosphatases (LMWPTPs) and arsenate reductases. ArsA exhibited weak phosphatase activity toward p-nitrophenyl phosphate, and high arsenate reductase activity, suggesting that ArsA may play a role in arsenate reductase, but not LMWPTP.",
Arsenic,1794733,"Arsenicosis and dietary nutrient intake among men and women Abstract: To determine the dietary intake of nutrients and its correlation with manifestations of arsenicosis and gender a cross-sectional study was conducted in India among two groups of participants, Group 1 (108 cases having skin lesions) and Group 2 (exposed controls, 100 cases not having skin lesions) with exposure to arsenic drawn from geographical areas known to have high level of arsenic in ground water (above permissible limit, i.e. >50 ?g/L). For diet survey, combinations of two methods of diet study i.e. weighment of cooked food and the 24-h diet recall were followed. The nutrients in each food items and calorie consumption were calculated. The mean calorie intake of males was significantly less than that of females in both cases and controls. In both the sexes, mean protein consumption was significantly less than that of the controls. In females, intake of most of the nutrients like thiamin, riboflavin, niacin, magnesium, copper and zinc were less in comparison to controls. In both the sexes mean choline intake was lower significantly in comparison to exposed controls. Riboflavin, copper, zinc and vitamin B6 consumption were below the RDAs in nearly 90 % of the study population. The strongest trend in ORs was for protein (4.28). The present study revealed that low socio-economic status along with dietary intake of calorie, protein and micronutrients like thiamine, riboflavin, niacin, zinc and choline may have a definite role in increasing the risk of development of arsenicosis.",
Arsenic,735046,"Formation of dimethylthioarsenicals in red blood cells Abstract: The bladder and skin are the primary targets for arsenic-induced carcinogenicity in mammals. Thioarsenicals dimethylmonothioarsinic (DMMTA(V)) and dimethyldithioarsinic (DMDTA(V)) acids are common urinary metabolites, the former being much more toxic than non-thiolated dimethylarsinic acid (DMA(V)) and comparable to dimethylarsinous acid (DMAIII) in epidermoid cells, suggesting that the metabolic production of thioarsenicals may be a risk factor for the development of cancer in these organs. To reveal their production sites (tissues/body fluids), we examined the uptake and transformation of the four dimethylated arsenicals by incubation with rat and human red blood cells (RBCs). Although DMA(V) and DMDTA(V) were not taken up by either type of RBCs, DMAIII and DMMTA(V) were taken up by both (more efficiently by rat ones), though DMMTA(V) was taken up slowly, and then the arsenic transformed into DMDTA(V) was excreted from both types of animal RBCs. On the other hand, although DMA(III) taken up rapidly by rat RBCs was retained in the RBCs, that taken up by human RBCs was immediately transformed into DMMTA(V) and then excreted into the incubation medium without being retained in the RBCs. In a separate experiment, arsenic remaining in primary rat hepatocytes after incubation with 1.5 microM DMAIII was recovered from the incubation medium in the forms of DMA(V) and DMMTA(V) in the presence of human RBCs, but not in the presence of rat RBCs (in which the arsenic was bound to hemoglobin). Thus, DMMTA(V) was detected in the medium only in the presence of human RBCs and increased with incubation time. It was proposed that arsenic is excreted from hepatocytes into the bloodstream in the form of DMAIII and then taken up by RBCs in humans, where it is transformed into DMMTA(V) and then excreted again into the bloodstream.",
Arsenic,627465,"Lung and kidney cancer mortality associated with arsenic in drinking water in Córdoba, Argentina Abstract: BACKGROUND: Studies in Taiwan have found dose-response relations between arsenic ingestion from drinking water and cancers of the skin, bladder, lung, kidney and liver. To investigate these associations in another population, we conducted a study in Córdoba, Argentina, which has a well-documented history of arsenic exposure from drinking water. METHODS: Mortality from lung, kidney, liver and skin cancers during the period 1986-1991 in Córdoba's 26 counties was investigated, expanding the authors' previous analysis of bladder cancer in the province. Counties were grouped a priori into low, medium and high arsenic exposure categories based on available data. Standardized mortality ratios (SMR) were calculated using all of Argentina as the reference population. RESULTS: We found increasing trends for kidney and lung cancer mortality with arsenic exposure, with the following SMR, for men and women respectively: kidney cancer, 0.87, 1.33, 1.57 and 1.00, 1.36, 1.81; lung cancer, 0.92, 1.54, 1.77 and 1.24, 1.34, 2.16 (in all cases, P < 0.001 in trend test), similar to the previously reported bladder cancer results (0.80, 1.28, 2.14 for men, 1.22, 1.39, 1.81 for women). There was a small positive trend for liver cancer but mortality was increased in all three exposure groups. Skin cancer mortality was elevated for women only in the high exposure group, while men showed a puzzling increase in mortality in the low exposure group. CONCLUSIONS: The results add to the evidence that arsenic ingestion increases the risk of lung and kidney cancers. In this study, the association between arsenic and mortality from liver and skin cancers was not clear.",
Arsenic,2064303,"A highly sensitive hybrid organic-inorganic sensor for continuous monitoring of hemoglobin Abstract: Microelectronic-based sensors are ideal for real-time continuous monitoring of health states due to their low cost of production, small size, portability, and ease of integration into electronic systems. However, typically semiconductor-based devices cannot be operated in aqueous solutions, especially in solutions with a low pH. However, in this work we overcame this difficulty and demonstrated the feasibility of a hemoglobin sensing array based on hybrid organic GaAs-based devices, which can remain in biological solutions for more than 24h. This was achieved by coating devices with a nanometer-thick polymer protective layer with subsequent adsorption of antibodies on its surface. The device is capable of functioning even in harsh physiological fluids, such as urine and bile juice. The surface modification allows a change in electrical potential, created by the interaction, to be efficiently transferred to the surface of the semiconductor device. By utilizing an array configuration, it is possible to obtain high sensitivity and selectivity.",
Arsenic,2345669,"Roles for root iron plaque in sequestration and uptake of heavy metals and metalloids in aquatic and wetland plants Abstract: Toxic metal(loid) contamination of soil and sediment poses long term risk to soil and human health through plant-human or plant-animal-human food chain pathways. Iron plaque (IP) formation is frequent in aquatic and wetland plant species and is responsible for the sequestration of various metal(loids). The presence of IP may act as a buffer or barrier and may thus enhance or reduce the uptake of potentially phytotoxic metals and metalloids by plants. If IP acts as a barrier, then low IP producing macrophytes/aquatic plants may be better accumulators of toxic metals and may find use in constructed wetlands for remediation of pollutants, while high IP forming edible plant species could be safer for human consumption. Conversely, if IP acts as a buffer for mineral nutrients and toxic elements then those cultivars may be rich in nutrients, but may also cause toxicity. However, an ecotoxicological risk is also inevitable if IP rich macrophyte roots containing heavy metals are consumed by herbivores. In this review, we summarize the current understanding about the role of IP in metal and metalloid sequestration, uptake, and transport. Furthermore, we will address the role of root IP in Oryza sativa for arsenic (As) sequestration leading to lower grain As translocation, reducing the risk of human exposure.",
Arsenic,1579254,"COMPARISON OF SLAUGHTER YIELD, CONTENTS OF BASIC NUTRIENTS, AND HEAVY METALS LEVELS IN MUSCLES OF CARP (CYPRINUS CARPIOL.) FARMED IN VARIOUS REGIONS IN POLAND Abstract: ",
Arsenic,1350040,"Involvement of the tyrosine phosphorylation pathway in induction of human heme oxygenase-1 by hemin, sodium arsenite, and cadmium chloride Abstract: The effect of a tyrosine kinase inhibitor, herbimycin A, on the induction of heme oxygenase-1 (HO-1) mRNA in HeLa cells upon exposure to hemin, sodium arsenite and cadmium chloride was examined. The induction of HO-1 mRNA by hemin was inhibited when the cells were pretreated with herbimycin A. Herbimycin also inhibited arsenite- and cadmium-dependent induction of HO-1 mRNA in a dose-dependent manner, but less inhibition was observed in cadmium-treated cells than in ones treated with hemin- or arsenite. Genistein (50 microM), another tyrosine kinase inhibitor, also inhibited the induction of HO-1 mRNA by hemin, arsenite, and cadmium. Nuclear runoff assays revealed that herbimycin blocked the hemin-induced transcription of the HO-1 gene. The induction of HO-1 mRNA by hemin in human peripheral blood mononuclear cells was inhibited by herbimycin. The tyrosine phosphorylation of a protein with a molecular mass of 66 kDa in the cells was increased by hemin- or arsenite-treatment, and this increase was inhibited by treatment with 5 microM herbimycin. When HeLa cells were treated with a specific inhibitor of the mitogen-activated protein kinase (MAPK)/extracellular-signal regulated kinase cascade, PD58059 (100 microM), suppression of the cadmium-dependent HO-1 induction was not observed, but the hemin- or arsenite-dependent induction was slightly inhibited. SB203580, an inhibitor of p38 MAPK, did not affect the HO-1 induction. These results indicated that signal transduction involving tyrosine kinase rather than the MAPK family regulates the induction of human HO-1 gene expression by stress inducers.",
Arsenic,1255520,"Increasing arsenic sorption on red mud by phosphogypsum addition Abstract: Mining by-products have been tested as adsorbents for arsenic in order to reduce As bioavailability. This study evaluated a red mud (RM) treated with or without phosphogypsum (G) in order to improve its As retention. Red mud and G samples and their mixtures were chemically and mineralogically characterized to gather information concerning their composition, which is key for a better understanding of the adsorbent properties. Phosphogypsum was added to RM in the following proportions: 0, 1, 2, 5, 10, and 25% by weight. These mixtures were subjected to As adsorption and desorption and tested for their maximum adsorption capacity of As (As(MAC)). Arsenic adsorption increased upon increasing the proportion of G added to RM. The As(MAC) at pure RM reached 909mgkg(-1), whereas the 75%-RM+25%-G mixture sorbed up to 3333mgkg(-1) of As, i.e., a 3.5-fold increase in As(MAC). Using G in mixtures with RM increases the efficiency of As adsorption due to the presence of Ca(2+), which alters the charge balance of the adsorbent, leading to the formation of ternary complexes. Addition of G to RM is thus a promising technique to improve As retention, while providing additional value to both by-products, G and RM.",
Arsenic,2088559,"Oral nanoparticulate curcumin combating arsenic-induced oxidative damage in kidney and brain of rats Abstract: Arsenic exposure through drinking water causes oxidative stress and tissue damage in the kidney and brain. Curcumin (CUR) is a good antioxidant with limited clinical application because of its hydrophobic nature and limited bioavailability, which can be overcome by the encapsulation of CUR with nanoparticles (NPs). The present study investigates the therapeutic efficacy of free CUR and NP-encapsulated CUR (CUR-NP) against sodium arsenite-induced renal and neuronal oxidative damage in rat. The CUR-NP prepared by emulsion technique and particle size ranged between 120 and 140 nm, with the mean particle size being 130.8 nm. Rats were divided into five groups (groups 1-5) with six animals in each group. Group 1 served as control. Group 2 rats were exposed to sodium arsenite (25 ppm) daily through drinking water for 42 days. Groups 3, 4, and 5 were treated with arsenic as in Group 2; however, these animals were also administered with empty NPs, CUR (100 mg/kg body weight), and CUR-NP (100 mg/kg), respectively, by oral gavage during the last 14 days of arsenic exposure. Arsenic exposure significantly increased serum urea nitrogen and creatinine levels. Arsenic increased lipid peroxidation (LPO), reduced glutathione content and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were depleted significantly in both kidney and brain. Treatment with free CUR and CUR-NP decreased the LPO and increased the enzymatic and nonenzymatic antioxidant system in kidney and brain. Histopathological examination showed that kidney and brain injury mediated by arsenic was ameliorated by treatment. However, the amelioration percentage indicates that CUR-NP had marked therapeutic effect on arsenic-induced oxidative damage in kidney and brain tissues.",1
Arsenic,1508540,"Thermodynamic and kinetic studies of As(V) removal from water by zirconium oxide-coated marine sand Abstract: Arsenic contamination of groundwater is a major threat to human beings globally. Among various methods available for arsenic removal, adsorption is fast, inexpensive, selective, accurate, reproducible and eco-friendly in nature. The present paper describes removal of arsenate from water on zirconium oxide-coated sand (novel adsorbent). In the present work, zirconium oxide-coated sand was prepared and characterised by infrared and X-ray diffraction techniques. Batch experiments were performed to optimise different adsorption parameters such as initial arsenate concentration (100-1,000 ?g/L), dose (1-8 g/L), pH of the solution (2-14), contact time (15-150 min.), and temperature (20, 30, 35 and 40 °C). The experimental data were analysed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Furthermore, thermodynamic and kinetic parameters were evaluated to know the mode of adsorption between ZrOCMS and As(V). The maximum removal of arsenic, 97 %, was achieved at initial arsenic concentration of 200 ?g/L, after 75 min at dosage of 5.0 g/L, pH?7.0 and 27?±?2 °C. For 600 ?g/L concentration, the maximum Langmuir monolayer adsorption capacity was found to be 270 ?g/g at 35 °C. Kinetic modelling data indicated that adsorption process followed pseudo-second-order kinetics. The mechanism is controlled by liquid film diffusion model. Thermodynamic parameter, ?H°, was -57.782, while the values of ?G° were -9.460, -12.183, -13.343 and -13.905 kJ/mol at 20, 30, 35 and 40 °C, respectively, suggesting exothermic and spontaneous nature of the process. The change in entropy, ?S°?=?-0.23 kJ/mol indicated that the entropy decreased due to adsorption of arsenate ion onto the solid adsorbent. The results indicated that the reported zirconium oxide-coated marine sand (ZrOCMS) was good adsorbent with 97 % removal capacity at 200 ?g/L concentration. It is interesting to note that the permissible limit of arsenic as per World Health Organization is 10 ?g/L, and in real situation, this low concentration can be achieved through this adsorbent. Besides, the adsorption capacity showed that this adsorbent may be used for the removal of arsenic from any natural water resource.",
Arsenic,1579380,"THE ANALYSIS OF PLANT-BASED RAW MATERIALS OF UNKNOWN ORIGIN Abstract: Chosen aspects of the safety of use of several herbs received from National Medicines Institute, which came from smuggling, have been examined. The analysis has been conducted in three different aspects: (1) Possibilities of contamination of plant-based raw materials by metals of heavy elements (As, Cd, Cu, Cr, Pb). (2) Conscious smuggling of intoxicating preparation or narcotics in plant-based raw materials. (3) Radioactive contamination originating mostly from 137Cs isotope. To solve the problem, analytical methods of GFAAS and ICP-MS, X-ray diffraction and high-distributive spectrometry of gamma-radiation have been applied. Determined concentration of arsenic in all analyzed samples and the concentration of lead in one sample exceeded allowable concentration recommended by WHO. In analyzed materials, no presence of narcotics or radioactive contamination of 137Cs isotope has been detected.",
Arsenic,2278594,"Prostate tissue metal levels and prostate cancer recurrence in smokers Abstract: Although smoking is not associated with prostate cancer risk overall, smoking is associated with prostate cancer recurrence and mortality. Increased cadmium (Cd) exposure from smoking may play a role in progression of the disease. In this study, inductively coupled plasma mass spectrometry was used to determine Cd, arsenic (As), lead (Pb), and zinc (Zn) levels in formalin-fixed paraffin embedded tumor and tumor-adjacent non-neoplastic tissue of never- and ever-smokers with prostate cancer. In smokers, metal levels were also evaluated with regard to biochemical and distant recurrence of disease. Smokers (N?=?25) had significantly higher Cd (median ppb, p?=?0.03) and lower Zn (p?=?0.002) in non-neoplastic tissue than never-smokers (N?=?21). Metal levels were not significantly different in tumor tissue of smokers and non-smokers. Among smokers, Cd level did not differ by recurrence status. However, the ratio of Cd ppb to Pb ppb was significantly higher in both tumor and adjacent tissue of cases with distant recurrence when compared with cases without distant recurrence (tumor tissue Cd/Pb, 6.36 vs. 1.19, p?=?0.009, adjacent non-neoplastic tissue Cd/Pb, 6.36 vs. 1.02, p?=?0.038). Tissue Zn levels were also higher in smokers with distant recurrence (tumor, p?=?0.039 and adjacent non-neoplastic, p?=?0.028). These initial findings suggest that prostate tissue metal levels may differ in smokers with and without recurrence. If these findings are confirmed in larger studies, additional work will be needed to determine whether variations in metal levels are drivers of disease progression or are simply passengers of the disease process.",
Arsenic,1034973,"Hyperthermia, Na+K+ATPase and lactic acid production in some human tumour cells Abstract: When HeLa cells are exposed to brief heat shock at 45 degrees C there is a reduction in the cellular level of Na+K+ATPase. Return of the cells to the normal growth temperature of 37 degrees C leads to a partial restoration of enzyme activity. The pattern of this recovery of activity suggests that it may be associated with the induction of heat shock proteins. Indeed other means of heat shock protein induction such as continuous heat treatment at 42 degrees C, or treatment of cells at 37 degrees C with sodium arsenite, leads to elevated levels of Na+K+ATPase activity and alterations in the kinetic properties of the enzyme. Continuous hyperthermia at 42 degrees C led to increased lactate production which could be blocked with ouabain suggesting that effects on Na+K+ATPase activity could partly influence glycolysis. A number of other human and hamster cells also showed increased lactate production at 42 degrees C and also an inhibition of lactate production by ouabain. Whilst incubation of HeLa cells with cyanide had little effect on glycolysis at 37 degrees C elevation of the temperature to 42 degrees C (or 45 degrees C), in the presence of cyanide, impaired glycolysis. The possible role in this phenomenon, of an unusual oxygen-sensitive isoenzyme of lactate dehydrogenase, expressed in human cancers, is discussed.",
Arsenic,1936195,THE USE OF WATER PLANTS IN BIOMONITORING AND PHYTOREMEDIATION OF WATERS POLLUTED WITH HEAVY METALS Abstract: ,
Arsenic,2278656,"The intake of inorganic arsenic from long grain rice and rice-based baby food in Finland - low safety margin warrants follow up Abstract: We evaluated total and inorganic arsenic levels in long grain rice and rice based baby foods on Finnish market. Inorganic arsenic was analysed with an HPLC-ICP-MS system. The total arsenic concentration was determined with an ICP-MS method. In this study, the inorganic arsenic levels in long grain rice varied from 0.09 to 0.28mg/kg (n=8) and the total arsenic levels from 0.11 to 0.65mg/kg. There was a good correlation between the total and inorganic arsenic levels in long grain rice at a confidence level of 95%. The total arsenic levels of rice-based baby foods were in the range 0.02 - 0.29mg/kg (n=10), however, the level of inorganic arsenic could only be quantitated in four samples, on average they were 0.11mg/kg. Our estimation of inorganic arsenic intake from long grain rice and rice-based baby food in Finland indicate that in every age group the intake is close to the lowest BMDL0.1 value 0.3?g/kg bw/day set by EFSA. According to our data, the intake of inorganic arsenic should be more extensively evaluated.",
Arsenic,1788718,"Maternal exposure to metals--Concentrations and predictors of exposure Abstract: A variety of metals are important for biological function but have also been shown to impact health at elevated concentrations, whereas others have no known biological function. Pregnant women are a vulnerable population and measures to reduce exposure in this group are important. We undertook a study of maternal exposure to the metals, aluminium, arsenic, copper, cobalt, chromium, lithium, manganese, nickel, selenium, tin, uranium and zinc in 173 participants across Western Australia. Each participant provided a whole blood and urine sample, as well as drinking water, residential soil and dust samples and completed a questionnaire. In general the concentrations of metals in all samples were low with the notable exception of uranium (blood U mean 0.07µg/L, range &lt;0.01-0.25µg/L; urinary U mean 0.018µg/g creatinine, range &lt;0.01-0.199µg/g creatinine). Factors that influenced biological concentrations were consumption of fish which increased urinary arsenic concentrations, hobbies (including mechanics and welding) which increased blood manganese concentrations and iron/folic acid supplement use which was associated with decreased concentrations of aluminium and nickel in urine and manganese in blood. Environmental concentrations of aluminium, copper and lithium were found to influence biological concentrations, but this was not the case for other environmental metals concentrations. Further work is underway to explore the influence of diet on biological metals concentrations in more detail. The high concentrations of uranium require further investigation.",
Arsenic,627069,"Gene expression changes and induction of cell proliferation by chronic exposure to arsenic of mouse testicular Leydig cells Abstract: Arsenic is an important environmental carcinogen that affects millions of people worldwide through contaminated water supplies. Chronic exposure of arsenic has been shown to induce malignant transformation of mammalian cells; however, the mechanism underlying arsenic-induced carcinogenesis is not clear. The (1) induction in the cell proliferation, (2) decrease in DNA repair capacity resulting in the accumulation of mutations, and (3) changes in the DNA methylation patterns affecting regulation of genes are hallmarks of cancer development. Thus, the purpose of this study was to determine whether long-term exposure of both low and high concentrations of arsenic can perturb cell proliferation, DNA repair, and the maintenance of DNA methylation status in TM3 cells, an immortalized Leydig cell derived from normal mouse testis. The effect of arsenic on cell proliferation was determined by cell count data, and arsenic-induced gene expression changes were measured by quantitative real-time polymerase chain reduction (PCR). The results this study revealed a concentration-dependent induction of cell proliferation by arsenic. Increased expression of cell proliferation marker genes (PCNA, CyclinD1) and DNA methylation (DNA Methyl Transferase I) and decreased expression of genes for DNA repair (DNA Polymerase beta, ERCC6) with lower concentrations of arsenic was also observed. Thus, the findings of this study are novel, as they indicate a mechanism for arsenic-induced cancers. This is based on the observed increase in cell proliferation and decrease in the capacity of cells to maintain its genomic stability. Our study provides the evidence that arsenic may play a role in the etiology of testicular cancer.",
Arsenic,1003587,"The contribution of microbial mats to the arsenic geochemistry of an ancient gold mine Abstract: The ancient Zloty Stok (SW Poland) gold mine is such an environment, where different microbial communities, able to utilize inorganic arsenic species As(III) and As(V), are found. The purpose of the present study was to (i) estimate prokaryotic diversity in the microbial mats in bottom sediments of this gold mine, (ii) identify microorganisms that can metabolize arsenic, and (iii) estimate their potential role in the arsenic geochemistry of the mine and in the environment. The oxidation/reduction experiments showed that the microbial mat community may significantly contribute to arsenic contamination in groundwater. The presence of both arsenite oxidizing and dissimilatory arsenate reducing bacteria in the mat was confirmed by the detection of arsenite oxidase and dissimilatory arsenate reductase genes, respectively. This work also demonstrated that microorganisms utilizing other compounds that naturally co-occur with arsenic are present within the microbial mat community and may contribute to the arsenic geochemistry in the environment.",
Arsenic,2278462,"Batch and fixed-bed column studies of arsenic adsorption on the natural and modified clinoptilolite Abstract: The samples of natural and iron-modified clinoptilolite (GC, Na-GC, Fe1-GC, and Fe2-GC) were assessed as adsorbent for arsenate removal by batch and column studies. The influences of retention time, pH, adsorbent dosage, and initial arsenate concentration on the arsenate adsorption efficiency were investigated. The experiments demonstrated that Fe1-GC has the highest arsenate removal efficiency with the adsorption capacity of 8.4 mu g g(-1) at equilibrium time of 60 min. Both the Fe1-GC and Fe2-GC removed arsenate effectively over the initial pH range 4-10. Adsorption capacity of Fe1-GC was adequately described by Freundlich isotherm. According to the results of the desorption performance experiments, the Fe1-GC was used six times until arsenic removal efficiency was reduced to 19 %. The adsorption percentage of arsenic increased with the diminish of initial concentration of arsenic and increase of adsorbent dose for all types of clinoptilolite. The column study demonstrated that Fe1-GC was achieved to reduce final arsenate of about 10 mu g L-1 or below for up to 300 bed volumes in a continuous flow mode. The results of this study show that Fe1-GC can be used as an alternative adsorbent for arsenate removal.",
Arsenic,1508542,"Speciation of arsenic in marine food (Anemonia sulcata) by liquid chromatography coupled to inductively coupled plasma mass spectrometry and organic mass spectrometry Abstract: Arsenic species have been investigated in Anemonia sulcata, which is frequently consumed food staple in Spain battered in wheat flour and fried with olive oil. Speciation in tissue extracts was carried out by anion/cation exchange chromatography with inductively coupled plasma mass spectrometry (HPLC-(AEC/CEC)-ICP-MS). Three methods for the extraction of arsenic species were investigated (ultrasonic bath, ultrasonic probe and focused microwave) and the optimal one was applied. Arsenic speciation was carried out in raw and cooked anemone and the dominant species are dimethylarsinic acid (DMAV) followed by arsenobetaine (AB), AsV, monomethylarsonic acid (MAV), tetramethylarsonium ion (TETRA) and trimethylarsine oxide (TMAO). In addition, arsenocholine (AsC), glyceryl phosphorylarsenocholine (GPAsC) and dimethylarsinothioic acid (DMAS) were identified by liquid chromatography coupled to triple quadrupole mass spectrometry (HPLC-MS). These results are interesting since GPAsC has been previously reported in marine organisms after experimental exposure to AsC, but not in natural samples. In addition, this paper reports for the first time the identification of DMAS in marine food.",
Arsenic,1351067,Designing Iron-Amended Biosand Filters for Decentralized Safe Drinking Water Provision Abstract: ,
Arsenic,2088413,Geochemical mapping of Spitsbergen in the High Arctic using overbank sediments of deltas and floodplains Abstract: ,
Arsenic,1797777,"Electrochemically Driven Catalysis of Rhizobium sp. NT-26 Arsenite Oxidase with its Native Electron Acceptor Cytochrome c552 Abstract: We describe the catalytic voltammetry of the periplasmic arsenite oxidase (Aio) from the chemolithoautotrophic bacterium Rhizobium sp. str. NT-26 that oxidizes arsenite to arsenate. Electrochemistry of the enzyme was accomplished using its native electron transfer partner, cytochrome c552 (cyt c552), as a mediator. The protein cyt c552 adsorbed on a mercaptoundecanoic acid (MUA) modified Au electrode exhibited a stable, reversible one-electron voltammetric response at +275mV vs NHE (pH7). In the presence of arsenite and Aio the voltammetry of cyt c552 is transformed from a transient response to an amplified sigmoidal (steady state) wave consistent with an electro-catalytic system. Digital simulation was performed using single set of enzyme dependent parameters for all catalytic voltammetry obtained at different sweep rates and various substrate concentrations. The obtained kinetic constants from digital simulation provide new insight into the kinetics of the NT-26 Aio catalytic mechanism.",
Arsenic,628009,"Chronic arsenic exposure and adverse pregnancy outcomes in Bangladesh Abstract: BACKGROUND: Chronic exposure to arsenic through drinking water has the potential to cause adverse pregnancy outcomes, although the association has not been demonstrated conclusively. This cross-sectional study assessed the association between arsenic in drinking water and spontaneous abortion, stillbirth, and neonatal death. METHODS: In this cross-sectional study, 533 women were interviewed. Information on sociodemographic characteristics, drinking water use, and adverse pregnancy outcomes was obtained through a structured pretested interviewer-administered questionnaire. The respondents reported use of a total of 223 tube wells; for 208 wells, water samples were measured using an ultraviolet/visible spectrophotometry method, whereas 15 were measured by flow-injection hydride generation atomic absorption spectrometry (FIHG-AAS). RESULTS: Excess risks for spontaneous abortion and stillbirth were observed among the participants chronically exposed to higher concentrations of arsenic in drinking water after adjusting for participant's height, history of hypertension and diabetes, and (for neonatal death only) age at first pregnancy. Comparing exposure to arsenic concentration of greater than 50 microg/L with 50 microg/L or less, the odds ratios were 2.5 (95% confidence interval=1.5-4.3) for spontaneous abortion, 2.5 (1.3-4.9) for stillbirth, and 1.8 (0.9-3.6) for neonatal death. CONCLUSIONS: These study findings suggest that chronic arsenic exposure may increase the risk of fetal and infant death.",
Arsenic,1026017,"Effects of time and point-of-use devices on arsenic levels in Southeastern Michigan drinking water, USA Abstract: Health effects associated with chronic, low-level exposures to arsenic in drinking water (&lt;100 microg/L) remain unclear, in part due to uncertainties in assessing exposure. Drinking water concentrations have been used to assess past exposure to arsenic in epidemiological studies, under the assumption that a single measurement can be used to estimate historical exposure. This study aims to better understand (1) temporal variability in arsenic concentrations in drinking water and (2) the impact of point-of-use (POU) treatment devices on arsenic exposure measurements, and on reliability of the exposure measurement for population-level studies. Multiple drinking water samples were collected at two points in time (an average of fourteen months apart) for 261 individuals enrolled in a case-control study of arsenic exposure and bladder cancer in Michigan. Sources of drinking water included private wells (n = 221), public water supplies (n = 33), and bottled water (n = 7); mean arsenic concentration was highest in private wells (7.28 microg/L) and lowest in bottled water samples (0.28 microg/L). Arsenic concentrations in primary drinking water samples were highly correlated (r = 0.88, p &lt; 0.0001, n = 196), with 3% of the water sources exceeding the United States Environmental Protection Agency's Maximum Contaminant Level (MCL) in one sample but not in the other sample. Measurement reproducibility did not vary by type of POU device (e.g., softener, filter, reverse osmosis system). Arsenic concentrations did differ, however, between samples treated with POU devices and untreated samples taken on the same day. Substantial differences in arsenic concentrations were consistently observed for reverse osmosis systems; other POU devices had variable effects on arsenic concentrations. These results indicate that while a single residential arsenic measurement may be used to represent exposure in this region, researchers must obtain information on changes in water source and POU treatment devices to better characterize population exposures over time.",
Arsenic,2088416,"Arsenic, tobacco smoke, and occupation: Associations of multiple agents with lung and bladder cancer Abstract: <strong>BACKGROUND: </strong>Millions of people worldwide are exposed to arsenic in drinking water, and many are likely coexposed to other agents that could substantially increase their risks of arsenic-related cancer.<br /><br /><strong>METHODS: </strong>We performed a case-control study of multiple chemical exposures in 538 lung and bladder cancer cases and 640 controls in northern Chile, an area with formerly high drinking water arsenic concentrations. Detailed information was collected on lifetime arsenic exposure, smoking, secondhand smoke, and other known or suspected carcinogens, including asbestos, silica, and wood dust.<br /><br /><strong>RESULTS: </strong>Very high lung and bladder cancer odds ratios (ORs), and evidence of greater than additive effects, were seen in people exposed to arsenic concentrations &gt;335 µg/L and who were tobacco smokers (OR = 16, 95% confidence interval = 6.5-40 for lung cancer; and OR = 23 [8.2-66] for bladder cancer; Rothman Synergy Indices = 4.0 [1.7-9.4] and 2.0 [0.92-4.5], respectively). Evidence of greater than additive effects were also seen in people coexposed to arsenic and secondhand tobacco smoke and several other known or suspected carcinogens, including asbestos, silica, and wood dust.<br /><br /><strong>CONCLUSIONS: </strong>These findings suggest that people coexposed to arsenic and other known or suspected carcinogens have very high risks of lung or bladder cancer.",
Arsenic,1016929,"Role of the Multidrug Resistance Protein 1 in protection from heavy metal oxyanions: investigations in vitro and in MRP1-deficient mice Abstract: The Multidrug Resistance Protein 1 (MRP1) is a membrane pump that mediates the efflux of a wide variety of xenobiotics, including arsenical and antimonial compounds, as demonstrated by the study of MRP1-transfected cell lines. We have previously shown that mrp1(-/-) cells are hypersensitive to sodium arsenite, sodium arsenate, and antimony potassium tartrate. We now report that the retroviral vector-mediated overexpression of MRP1 and of the two subunits of gamma-GCS (heavy and light) resulted in higher intracellular glutathione levels and in a greater level of resistance to sodium arsenite and antimony potassium tartrate, compared to the overexpression of MRP1 and gamma-GCS heavy alone. These observations further demonstrate that glutathione is an important component of MRP1-mediated cellular resistance to arsenite and antimony. However, the constitutive expression of MRP1 did not protect mice from the lethality of sodium arsenite and antimony potassium tartrate nor reduced the tissue accumulation of arsenic in mice injected i.p. with sodium arsenite. It is conceivable that, in vivo, other pump(s) effectively vicariate for MRP1-mediated transport of heavy metal oxyanions.",
Arsenic,1247400,"Early-life or lifetime sun exposure, sun reaction, and the risk of squamous cell carcinoma in an Asian population Abstract: BACKGROUND: It has been widely accepted that sun exposure is a risk factor of squamous cell carcinoma (SCC) among fair-skinned populations. However, sun exposure and sun reaction have not been explored in Asians and no gender-specific data were available. METHOD: In a case-control study, 176 incident skin cancer cases were recruited from National Cheng-Kung University Medical Center from 1996 to 1999. Controls included 216 age-, gender-, and residency-matched subjects from the southwestern Taiwan. A questionnaire was administered to collect information on life style and other risk factors. Logistic regression analysis was performed to evaluate the association between sun exposure or sun reaction and the risk of SCC by gender. RESULTS: Early-age (age 15 to 24) and lifetime sun exposure were significantly associated with increased risk of SCC in a dose-response pattern [odds ratio (OR) = 1.49-3.08, trend p = 0.009 and 0.0007, respectively]. After stratified by gender, the third tertile of early-age sun exposure was significantly associated with the SCC risk among men (OR = 3.08). The second and third tertiles of lifetime sun exposure was significantly associated with SCC risk among women (OR = 3.78 and 4.53, respectively). Skin reaction after 2-h sun exposure during childhood and adolescence was not significantly associated with the risk of SCC. CONCLUSIONS: Lifetime sun exposure was more related to SCC risk in women, while early-age sun exposure was more relevant to men's SCC risk. This may be attributable to different lifestyle between men and women.",
Arsenic,1677575,"In utero arsenic exposure and infant infection in a United States cohort: A prospective study Abstract: Arsenic (As), a ubiquitous environmental toxicant, has recently been linked to disrupted immune function and enhanced infection susceptibility in highly exposed populations. In drinking water, as levels above the EPA maximum contaminant level occur in our US study area and are a particular health concern for pregnant women and infants. As a part of the New Hampshire Birth Cohort Study, we investigated whether in utero exposure to As affects risk of infant infections. We prospectively obtained information on 4-month-old infants (n=214) using a parental telephone survey on infant infections and symptoms, including respiratory infections, diarrhea and specific illnesses, as well as the duration and severity of infections. Using logistic regression and Poisson models, we evaluated the association between maternal urinary As during pregnancy and infection risks adjusted for potentially confounding factors. Maternal urinary As concentrations were related to total number of infections requiring a physician visit (relative risk (RR) per one-fold increase in As in urine=1.5; 95% confidence interval (CI)=1.0, 2.1) or prescription medication (RR=1.6; 95% CI=1.1, 2.4), as well as lower respiratory infections treated with prescription medication (RR=3.3; 95% CI=1.2, 9.0). Associations were observed with respiratory symptoms (RR=4.0; 95% CI=1.0, 15.8), upper respiratory infections (RR=1.6; 95% CI=1.0, 2.5), and colds treated with prescription medication (RR=2.3; 95% CI=1.0, 5.2). Our results provide initial evidence that in utero As exposure may be related to infant infection and infection severity and provide insight into the early life impacts of fetal As exposure.",
Arsenic,1936089,"Enhanced arsenite removal from water by Ti(SO4)2 coagulation Abstract: Coagulation with the conventional coagulants such as ferric and aluminum salts is not efficient for As(III) removal. In this study Ti(SO4)2 was employed for enhanced As(III) removal and Fe2(SO4)3 was used as a reference. The removal efficiencies of As(III) by Ti(SO4)2 at pH 4.0-9.0 were greater than that by Fe2(SO4)3 by 7.39-32.8% and 3.14-48.1% for coagulants dosed at 8.0 mg/L and 12.0 mg/L, respectively. The advantage of Ti(SO4)2 over Fe2(SO4)3 for As(III) removal was more significant at lower pH, which may be ascribed to the more negatively charged surface of Ti(IV) hydroxides. To reduce As(III) from 0.2 mg/L to 10 ?g/L, the necessary dosage of Ti(SO4)2 was only ?50% of that of Fe2(SO4)3. The adsorption capacity of As(III) on Ti(IV) hydroxides formed in-situ was greater than that on Fe(III) hydroxides formed in-situ by ?100 mg/g and several times higher than the adsorption capacities of TiO2 for As(III) reported in the literature. The presence of competing anions, silicate, phosphate and humic acid, did not alter the advantage of Ti(SO4)2 over Fe2(SO4)3 for arsenite removal. Replacing partial Ti(SO4)2 with Fe2(SO4)3 (same dosage) and applying them sequentially could achieve similar As(III) removal efficiency as single Ti(SO4)2, which could thus reduce the chemical cost. The extended X-ray absorption fine structure (EXAFS) spectroscopy indicated that As(III) form bidentate binuclear surface complexes with Ti(IV) hydroxides as evidenced by As(III)-Ti bond distances of 3.33-3.35 ?. This study revealed that Ti(SO4)2 may be an alternative coagulant for efficient As(III) removal.",
Arsenic,628446,"Evaluation of micronucleus frequencies and DNA damage in glass workers exposed to arsenic Abstract: Arsenic (As) is a known human carcinogen; however, very little is known about the health consequences of occupational exposure to As. In the present study, we assessed the genotoxic damage in the blood cells and in the buccal cells of south Indian glass factory workers who are occupationally exposed to As. The As content in the whole blood of 200 workers and 165 controls was evaluated with inductively coupled plasma mass spectrometry. Blood leukocytes from the subjects were monitored for the level of DNA damage using the Comet assay (mean comet tail length); buccal cells were used to determine the frequency of micronuclei (MN). The mean As concentration was significantly higher in the workers (56.76 microg/L) than in the controls (11.74 microg/L) (P < 0.001). The workers also had increased frequencies of MN in the buccal cells and increased levels of DNA damage in leukocytes compared to the controls (P < 0.001). There were significant correlations between the genotoxicity endpoints that were evaluated and blood As concentration, smoking, age, and the duration of working in the factory. Also, a significant correlation was observed between the frequency of MN and comet tail-length for the worker samples. Our findings indicate that chronic occupational exposure to As is genotoxic and that the Comet assay and micronucleus test are useful assays for evaluating genotoxicity in humans occupationally exposed to As.",
Arsenic,2347762,"Removal of organic compounds and trace metals from oil sands process-affected water using zero valent iron enhanced by petroleum coke Abstract: The oil production generates large volumes of oil sands process-affected water (OSPW), referring to the water that has been in contact with oil sands or released from tailings deposits. There are concerns about the environmental impacts of the release of OSPW because of its toxicity. Zero valent iron alone (ZVI) and in combination with petroleum coke (CZVI) were investigated as environmentally friendly treatment processes for the removal of naphthenic acids (NAs), acid-extractable fraction (AEF), fluorophore organic compounds, and trace metals from OSPW. While the application of 25 g/L ZVI to OSPW resulted in 58.4% removal of NAs in the presence of oxygen, the addition of 25 g petroleum coke (PC) as an electron conductor enhanced the NAs removal up to 90.9%. The increase in ZVI concentration enhanced the removals of NAs, AEF, and fluorophore compounds from OSPW. It was suggested that the electrons generated from the oxidation of ZVI were transferred to oxygen, resulting in the production of hydroxyl radicals and oxidation of NAs. When OSPW was de-oxygenated, the NAs removal decreased to 17.5% and 65.4% during treatment with ZVI and CZVI, respectively. The removal of metals in ZVI samples was similar to that obtained during CZVI treatment. Although an increase in ZVI concentration did not enhance the removal of metals, their concentrations effectively decreased at all ZVI loadings. The Microtox (R) bioassay with Vibrio fischeri showed a decrease in the toxicity of ZVI- and CZVI-treated OSPW. The results obtained in this study showed that the application of ZVI in combination with PC is a promising technology for OSPW treatment.",
Arsenic,1241382,"Arsenic release and speciation in a degraded fen as affected by soil redox potential at varied moisture regime Abstract: Soil surveys have demonstrated arsenic (As) contents of up to 1600 mg kg super(- 1) in surface horizons of degraded fens in the Bavarian Molasse basin, Germany. Ground water from the Tertiary aquifer seems to be the primary source of As. Yet, the cause of its accumulation in the topsoil is unclear. Focussing the influence of redox processes on As redistribution, we conducted soil column experiments with the A (716 mg As kg super(- 1)), Ag (293 mg As kg super(- 1)) and 2Ag (37 mg As kg super(- 1)) horizons of a Mollic Gleysol (pH 7.2). The fixed beds were equipped with redox electrodes and suction cups and subjected to a saturation-drainage-saturation cycle. Water table fluctuations were simulated by defined pressure heads applied to the lower column boundaries via a digitally controlled vacuum system. After water saturation, the redox potential (E sub(H)) dropped to minimum values of around 0 mV in the A/Ag and-400 mV in the 2Ag horizon. Soil drainage resulted in a quick return to oxidising conditions. Both in the A and Ag horizons total aqueous As concentrations were low (up to 20 kg l super(- 1)) and not related to E sub(H). In contrast, aqueous As concentrations of the 2Ag horizon were between 5 and 140 kg l super(- 1) and increased as the E sub(H) decreased. However, the As species distribution showed no clear trend with E sub(H) since both As(III) and As(V) were detected under reducing conditions. High release of As in the 2Ag horizon is consistent with low contents in Fe (hydr)oxides. In the A and Ag horizons, pedogenetic enrichment of sesquioxides contributes to a comparably lower sensitivity of E sub(H) to water saturation and favours As retention. Thereby, As released under saturated conditions in the 2Ag horizon may be stabilised in the topsoil following capillary rise. Thus, surface horizons may act both as historic and as recent sinks for geogenic As at the site.",
Arsenic,1342993,Arsenic salvage is superior to chemotherapy and bone marrow transplantation for relapsed acute promyelocytic leukemia: Ten years of experience from Hong Kong Abstract: ,
Arsenic,1337499,"Silicate Mineral Impacts on the Uptake and Storage of Arsenic and Plant Nutrients in Rice ( Oryza sativa L.) Abstract: Arsenic-contaminated rice grain may threaten human health globally. Since H(3)AsO(3)(0) is the predominant As species found in paddy pore-waters, and H(4)SiO(4)(0) and H(3)AsO(3)(0) share an uptake pathway, silica amendments have been proposed to decrease As uptake and consequent As concentrations in grains. Here, we evaluated the impact of two silicate mineral additions differing in solubility (+Si(L), diatomaceous earth, 0.29 mM Si; +Si(H), Si-gel, 1.1 mM Si) to soils differing in mineralogy on arsenic concentration in rice. The +Si(L) addition either did not change or decreased As concentration in pore-water but did not change or increased grain-As levels relative to the (+As-Si) control. The +Si(H) addition increased As in pore-water, but it significantly decreased grain-As relative to the (+As-Si) control. Only the +Si(H) addition resulted in significant increases in straw- and husk-Si. Total grain- and straw-As was negatively correlated with pore-water Si, and the relationship differed between two soils exhibiting different mineralogy. These differing results are a consequence of competition between H(4)SiO(4)(0) and H(3)AsO(3)(0) for adsorption sites on soil solids and subsequent plant-uptake, and illustrate the importance of Si mineralogy on arsenic uptake.",
Arsenic,1070378,"Use of chitosan and chitosan-derivatives to remove arsenic from aqueous solutions-a mini review Abstract: Arsenic removal has become a relevant concern due to the final confirmation of its behaviour as chronic human carcinogen, corresponding to an ever-increasing contamination of water, soil and crops in many parts of the world. Developing easily accessible removal strategies is therefore a primary environmental matter. Chitosan and chitosan derivatives show good adsorption performances against arsenic removal and are considered low cost products, easily obtainable. This review provides a summary of recent advances of the application of these compounds in the area of sorption sciences for arsenate and arsenite removal from water, focusing on equilibrium and kinetic mechanisms.",
Arsenic,1351366,Modulation of mercury-induced mitochondria-dependent apoptosis by glycine in hepatocytes Abstract: ,
Arsenic,2337270,"Arsenic hypertolerance in the protist Euglena mutabilis is mediated by specific transporters and functional integrity maintenance mechanisms Abstract: Arsenic is a toxic metalloid known to cause multiple and severe cellular damages, including lipid peroxidation, protein misfolding, mutagenesis and double and single-stranded DNA breaks. Thus, exposure to this compound is lethal for most organisms but some species such as the photosynthetic protist Euglena mutabilis are able to cope with very high concentrations of this metalloid. Our comparative transcriptomic approaches performed on both an arsenic hypertolerant protist, i.e. E.?mutabilis, and a more sensitive one, i.e. E.?gracilis, revealed multiple mechanisms involved in arsenic tolerance. Indeed, E.?mutabilis prevents efficiently the accumulation of arsenic in the cell through the expression of several transporters. More surprisingly, this protist induced the expression of active DNA reparation and protein turnover mechanisms, which allow E.?mutabilis to maintain functional integrity of the cell under challenging conditions. Our observations suggest that this protist has acquired specific functions regarding arsenic and has developed an original metabolism to cope with acid mine drainages-related stresses.",
Arsenic,2343561,"Macroscopic experimental and modeling evaluation of selenite and selenate adsorption mechanisms on gibbsite Abstract: Selenite Se(IV) and selenate Se(VI) adsorption behavior was investigated on gibbsite as a function of solution pH and solution ionic strength. Adsorption of both Se redox states decreased with increasing solution pH. Electrophoretic mobility measurements showed downward shifts in point of zero charge (PZC) indicative of the formation of inner-sphere Se(IV) and Se(VI) surface complexes. However, the downward shift was less than for strongly adsorbing anions such as phosphate and arsenate, suggesting that outer-sphere surface complexes are also present. The triple layer model, a chemical surface complexation model, was well able to describe Se(IV) and Se(VI) adsorption as a function of solution pH and solution ionic strength by simultaneously optimizing both inner-sphere and outer-sphere surface complexation constants. Direct spectroscopic investigations of selenite surface configuration are needed to corroborate the species suggested by the macroscopic experiments and obtained from the triple layer model optimizations.",
Arsenic,1579319,"Bayesian Networks as a screening tool for exposure assessment Abstract: A tiered approach to contamination exposure assessment is currently adopted in many countries. Increasing the site-specific information in exposure assessments is generally recommended when guideline values for contaminants in soil are exceeded. This work details a Bayesian Network (BN) approach to developing a site-specific environmental exposure assessment that focuses on the simple mapping and assessment of assumptions and the effect of new data on assessment outcomes. The BN approach was applied to a floodplain system in New South Wales, Australia, where site-specific information about elevated antimony (Sb) concentrations and distribution in soils was available. Guidelines for exposure assessment in Australia are used as a template for this site, although the approach is generic. The BN-based assessment used an iterative approach starting with limited soil Sb data (41 samples ranging from 0 to 18 mg kg-(1) Sb) and extending the model with more detailed Sb data (145 samples ranging from 0 to 40 mg kg-(1) Sb). The analyses identified dominant exposure pathways and assessed the sensitivity of these pathways to changes in assumptions and the level of site-specific information available. In particular, there was a 10.8% probability of exceeding the tolerable daily intake of Sb in the case study when the limited soil Sb data was used, which increased to 26.2% with the more detailed sampling regime. There was also a 47% decrease in the probability of overexposure to Sb when the dermal bioavailability of arsenic (a similar metalloid) was used as a surrogate measure instead of a default bioavailability of 100%. We conclude that the BN approach to soil exposure assessment has merit both in the context of Australian and international soil exposure assessments.",
Arsenic,626999,"Genotoxic effects of sodium arsenite on human cells Abstract: The effects of sodium arsenite (SA) were studied either alone or in combination with X-rays in peripheral blood lymphocytes, and with short-wave ultraviolet (UV) radiation in primary human fibroblast culture systems. It was found that SA (i) inhibited the cell cycle progression of phytohaemagglutinin (PHA)-responsive lymphocytes, (ii) induced chromatid-type aberrations and sister-chromatid exchanges (SCEs) as a function of concentration and (iii) potentiated the X-ray- and UV-induced chromosomal damage. Our results suggest that SA interferes with the DNA repair process, presumably by inhibiting the ligase activity. This accounted for an increase in the DNA replication-dependent processes, chromatid aberrations and SCEs and synergistic enhancement of the X-ray- and UV-induced chromosomal damage. This ability of arsenite may be responsible for its comutagenic properties with different types of mutagens and hence its carcinogenicity.",
Arsenic,1021838,"A program consisting of a phytonutrient-rich medical food and an elimination diet ameliorated fibromyalgia symptoms and promoted toxic-element detoxification in a pilot trial Abstract: <strong>BACKGROUND: </strong>An effective treatment for fibromyalgia (FM) has yet to become available.<br /><br /><strong>OBJECTIVE: </strong>To assess the efficacy ofa lifestyle program consisting of a modified elimination diet and a supplemental medical food on clinical symptoms of FM assessed by the Fibromyalgia Impact Questionnaire (FIQ), FibroQuest Symptoms Survey (FibroQuest), Medical Symptoms Questionnaire (MSQ), metallothionein mRNA expression, and urinary toxic element excretion.<br /><br /><strong>METHODS: </strong>Eight women (aged 48-74 years) were enrolled in an 8-week pilot trial employing a sequential design. During the initial 4-week Program A (control), participants consumed a modified US Department of Agriculture food pyramid diet and a rice protein powder supplement that provided basic macronutrient support. During the second 4-week Program B (intervention), participants consumed a modified elimination diet and a phytonutrient-rich medical food.<br /><br /><strong>RESULTS: </strong>Compared to baseline, both programs showed trends toward lower mean FIQ total score, MSQ total score, and FibroQuest total score, FIQ stiffness score, and FibroQuest headaches score. Compared to Program A, Program B resulted in a significant decrease (P&lt; .05) in the FIQpain score and stiffness score. Participants also had better pain tolerance at five tender points during Program B than during Program A. Higher metallothionein mRNA expression was observed during Program B. An increase in creatinine-adjusted mercury excretion and suggestive increase in creatinine-adjusted arsenic excretion were noted when Program B was compared to baseline. Urinary mercury/arsenic concentrations were inversely associated with FIQand FibroQuest scores.<br /><br /><strong>CONCLUSIONS: </strong>Program B was shown to be a safe and efficacious botanically derived medical food treatment program for the amelioration of FM symptoms.",
Arsenic,2064177,"Honey as a bioindicator of arsenic contamination due to volcanic and mining activities in Chile Abstract: The content of heavy metals in honey is indicative of natural or anthropogenic pollution and has therefore been proposed as a feasible bioindicator for arsenic contamination in different regions of Chile. Total arsenic (t-As) and inorganic As (i-As) concentrations were determined in 227 samples of honey harvested during the years 2007, 2008, and 2009 in the areas of San Pedro de Atacama, Atacama, Chiloé, and Futaleufú, with the last town located 156 km from the Chaitén Volcano (latest eruption in 2008). These analyses were conducted using an atomic absorption spectrophotometer coupled with a hydride generator. In the honey samples, the concentrations of t-As ranged from 2.2 to 171.9 ?g kg-1, and the i-As concentrations ranged from none detected (ND) to 24.6 ?g kg-1, with the area of San Pedro de Atacama having the highest As concentrations. The samples of honey from Futaleufú showed higher As concentrations after the eruption of the Chaitén Volcano in 2008. This study demonstrates that As pollution in honey may originate from both natural and anthropogenic sources. The results indicate that it is appropriate to use honey as a bioindicator of environmental pollution. In addition, the consumption of the honey studied herein does not pose any health hazards to the consumer due to its As content.",
Arsenic,2345666,"From community approaches to single-cell genomics: The discovery of ubiquitous hyperhalophilic Bacteroidetes generalists Abstract: The microbiota of multi-pond solar salterns around the world has been analyzed using a variety of culture-dependent and molecular techniques. However, studies addressing the dynamic nature of these systems are very scarce. Here we have characterized the temporal variation during 1 year of the microbiota of five ponds with increasing salinity (from 18% to &gt;40%), by means of CARD-FISH and DGGE. Microbial community structure was statistically correlated with several environmental parameters, including ionic composition and meteorological factors, indicating that the microbial community was dynamic as specific phylotypes appeared only at certain times of the year. In addition to total salinity, microbial composition was strongly influenced by temperature and specific ionic composition. Remarkably, DGGE analyses unveiled the presence of most phylotypes previously detected in hypersaline systems using metagenomics and other molecular techniques, such as the very abundant Haloquadratum and Salinibacter representatives or the recently described low GC Actinobacteria and Nanohaloarchaeota. In addition, an uncultured group of Bacteroidetes was present along the whole range of salinity. Database searches indicated a previously unrecognized widespread distribution of this phylotype. Single-cell genome analysis of five members of this group suggested a set of metabolic characteristics that could provide competitive advantages in hypersaline environments, such as polymer degradation capabilities, the presence of retinal-binding light-activated proton pumps and arsenate reduction potential. In addition, the fairly high metagenomic fragment recruitment obtained for these single cells in both the intermediate and hypersaline ponds further confirm the DGGE data and point to the generalist lifestyle of this new Bacteroidetes group.",
Arsenic,1579274,Phosphacycles as Building Blocks for Main Group Cages Abstract: ,
Arsenic,8307,"Cancer among workers exposed to arsenic and other substances in a copper smelter Abstract: A study of the mortality experience of 2802 men who worked one year or more during the period 1940-4964 at a copper smelter in Tacoma, Washington, where arsenic exposure occurred showed a twofold excess in respiratory cancer deaths. Using a time-weighted measure of exposure, a life table method for accumulating dose, and a 10-year lag period, the excess ranged from 1.5 in the lowest exposure category to 2.5 in the highest exposure category. Neither duration of exposure nor time since first exposure contributed strongly to the respiratory cancer excess. The twofold excess in respiratory cancer deaths held for workers with relatively short exposures (less than 10 years) and with a relatively short latency period (less than 20 years) as well as for those with longer exposure and latent periods. This appeared to be because the respiratory cancer excess tended to disappear with time for workers who terminated employment alive, and because workers in high-exposure jobs tended to terminate more quickly than workers in low-exposure jobs. A somewhat unorthodox analytic method showed a weak relationship between the respiratory cancer excess and exposure duration when exposure intensity was held constant. Here, arsenic exposure intensity made an independent contribution to the respiratory cancer excess.",
Arsenic,1025551,"Monomethylarsonous acid induced cytotoxicity and endothelial nitric oxide synthase phosphorylation in endothelial cells Abstract: Chronic arsenic poisoning is reported to be associated with peripheral and cardiovascular disease, arteriosclerosis, Raynaud's syndrome, hypertension, and Blackfoot disease. Monomethylarsonous acid (MMA(III)) is a reactive metabolite of inorganic arsenic and a potent inhibitor of endothelial nitric oxide synthase (eNOS). Arsenic is also reported to phosphorylate eNOS in cultured keratinocyte and Human T cell leukemia Jurkat cells, respectively. In the present study, we examined the cytotoxicity and eNOS phosphorylation by MMA(III) exposure in cultured bovine aortic endothelial cells (BAEC). Results showed that MMA(III) is more toxic than arsenite in BAEC cells. The IC(50) values for MMA(III) and arsenite were determined to be approximately 1.7 and 24.1 micromol/L, respectively. Exposure of BAEC to MMA(III) (0.75 micromol/L) caused a significant eNOS phosphorylation 15 min after MMA(III) exposure. However, a complex of MMA(III) with dithiothreitol (DTT) that lacks the reactivity with vicinal thiols unaffected eNOS phosphorylation. The present study shows that MMA(III )generated during biomethylation of arsenic is highly toxic in BAEC. Our study also suggests that MMA(III) could induce the eNOS phosphorylation through modification to cellular thiols of the eNOS enzyme. And the initial up-regulation of eNOS phosphorylation by MMA(III )seems to be an adaptive response against disruption of eNOS bioactivity during arsenic exposure.",
Arsenic,1018466,"Clinicopathological features of bladder cancer associated with chronic exposure to arsenic Abstract: A high incidence of bladder cancer has been documented in an area of chronic arsenic (As) exposure. This study investigates the characteristics of As-associated (n = 49) and other (n = 64) bladder cancers. A higher histological grading was observed for the As-exposed tumours (P = 0.04), but no other difference in pathobiological features or prognosis was found between the two groups.",
Arsenic,64046,"Lung cancer in a non-ferrous smelter: The role of cadmium Abstract: Lung cancer mortality was examined in a cohort of 4393 men employed at a zinc-lead-cadmium smelter. There was an excess of lung cancer (overall SMR = 124.5, 95% confidence interval 107-144) which was particularly evident for those employed for more than 20 years. A statistically significant trend in SMRs with increasing duration of employment was apparent. Quantitative estimates of exposure to cadmium and ordinal rankings for lead, arsenic, zinc, sulphur dioxide, and dust were used to calculate cumulative exposures from job histories. Matched logistic regression was used to compare the cumulative exposures of cases of lung cancer to those of controls matched for date of birth and date of starting work and surviving at the time of death of the matched cases. The increasing risk of lung cancer associated with increasing duration of employment could not be accounted for by cadmium and did not appear to be restricted to any particular process or department. Although lung cancer mortality was associated with estimates of cumulative exposure to arsenic and to lead, it was not possible to determine whether the increased risk might be due to arsenic, lead, or to other contaminants in the smelter. These results are compared with findings from other non-ferrous smelters.",
Arsenic,1244046,"JNK dependent Stat3 phosphorylation contributes to Akt activation in response to arsenic exposure Abstract: Environmental exposure to arsenic, especially the trivalent inorganic form (As3+), has been linked to human cancers in addition to a number of other diseases including skin lesions, cardiovascular disorders, neuropathy, and internal organ injury. In the present study, we describe a novel signaling axis of the c-Jun NH2 kinase (JNK) and signal transducer and activator of transcription 3 (Stat3) and its involvement in As3+-induced Akt activation in human bronchial epithelial cells. As3+ activates JNK and induces phoshporylation of the Stat3 at serine 727 (S727) in a dose- and time-dependent manner, which occurred concomitantly with Akt activation. Disruption of the JNK signaling pathway by treatment with the JNK inhibitor SP600125, siRNA knockdown of JNK, or genetic deficiency of the JNK1 or JNK2 gene abrogated As3+-induced S727 phosphorylation of Stat3, Akt activation, and the consequent release of vascular endothelial growth factor (VEGF) and migration of the cells. Similarly, pretreatment of the cells with Stat3 inhibitor or Stat3 siRNA prevented Akt activation and VEGF release from the cells in response to As3+ treatment. Taken together, these data revealed a new signaling mechanism that might be pivotal in As3+-induced malignant transformation of the cells by linking the key stress signaling pathway, JNK, to the activation of Stat3 and the carcinogenic kinase, Akt.",
Arsenic,1326964,"Coordination of JNK1 and JNK2 is critical for GADD45alpha induction and its mediated cell apoptosis in arsenite responses Abstract: Arsenite is a well documented environmental pathogen, whereas it has also been applied as medication to treat various neoplasmas. The pathogenic and therapeutic effects of arsenite are associated with cellular apoptotic responses. However, the molecular mechanisms of arsenite-induced apoptosis are not very well understood. Our previous study has shown that arsenite exposure is able to activate JNKs, which subsequently mediate the apoptotic outcome. The present study further revealed that the coordination of JNK1 and JNK2 was critical for the arsenite-induced expression of GADD45alpha (growth arrest and DNA damage 45alpha), which in turn mediated the cellular apoptosis. The arsenite-induced apoptosis and GADD45alpha expression were significantly impaired in mouse embryonic fibroblasts deficient in either jnk1 (JNK1-/-) or jnk2 (JNK2-/-). Knockdown of GADD45alpha by its specific small interfering RNA also dramatically reduced the apoptotic responses, and overexpression of GADD45alpha in either JNK1-/- or JNK2-/- mouse embryonic fibroblasts partially resensitized the cell death. Furthermore, it was found that the regulation of GADD45alpha by JNK1 and JNK2 was achieved through mediating the activation of c-Jun, since in the JNK1-/- and JNK2-/- cells the c-Jun activation was impaired, and overexpression of the dominant negative mutant of c-Jun (TAM67) in wild type cells could also block GADD45alpha induction as well as cellular apoptosis. Our results demonstrate that the coordination of JNK1 and JNK2 is critical for c-Jun/GADD45alpha-mediated cellular apoptosis induced by arsenite.",
Arsenic,2343429,"Species- and tissue-specific bioaccumulation of arsenicals in various aquatic organisms from a highly industrialized area in the Pohang City, Korea Abstract: Contamination of water and sediment with arsenic (As) in a highly industrialized area of Pohang City, Korea was investigated, with emphasis on in situ bioaccumulation of arsenicals by various aquatic organisms. Species- and tissue-specific concentrations of arsenicals were determined by use of HPLC-ICP/MS and ?-X-ray absorption near-edge structure (?-XANES). Concentrations of arsenic in aquatic organisms were strongly associated with corresponding water concentrations, which indicates point sources associated with land use and activities. Arsenobetaine was the most dominant form of arsenic found in fishes, bivalves, crabs, and shrimps, while As(III) was predominant in freshwater snails. The ?-XANES analysis provided additional information about the unidentified arsenicals such as As-thiol. Arsenicals were mainly localized in intestine of mullet and marsh clam. Distribution and bioaccumulation of arsenic were strongly correlated with salinity, which indicates that natural processes controlling biogeochemistry of arsenic would be important in estuarine lotic system.",
Arsenic,1015925,"Chemical forms and ecological risk of arsenic in the sediment of the Daliao River System in China Abstract: The chemical forms and ecological risk of As were characterized in the sediment of the Daliao River System (DRS), which has been affected by long-term intensive industrial, urban, and agricultural activities. Twenty-seven samples of surface sediment were collected and analyzed for total As content and that of its chemical forms. The results indicated that the average total As content in the sediment was 9.83 mg kg(?-?1) but that the levels ranged from 1.57 to 83.09 mg kg(?-?1). At the sites near cities, mining sites, and the estuary of the DRS, it is likely that adverse effects on aquatic organisms occur, due to As levels in the sediment that are often higher than the threshold effect level and occasionally higher than the probable effect level. A selectively sequential extraction indicated that the majority of As in the sediment was bound to Fe oxides (62.1%), with moderate proportions of residual As (19.8%), specifically adsorbed As (17.9%), and a low proportion of non-specifically adsorbed As (1.1%). In addition, the content of Fe in the sediment was positively and significantly correlated with the contents of amorphous and crystalline Fe oxide-bound As, confirming the crucial role of Fe oxides in immobilizing high amounts of As in superficial environments. The average molar ratio of As to Fe was 1.18 × 10(?-?4) in the surface sediment of the DRS, similar to that of natural Fe oxides, but much lower than that of synthesized Schwertmannite. Therefore, the release of As under reduced and low pH conditions can cause serious problems for water resources and for living organisms.",
Arsenic,1344566,"Study of the state of uranoarsenates M-II(AsUO6)(2)center dot nH(2)O(M-II = Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+) in aqueous solutions Abstract: State of uranoarsenates MII(AsUO6)2·nH2O (MII = Mn, Co, Ni, Cu, Zn, Cd, Pb) in aqueous solutions in a wide range of acidity (pH 0–14) was studied. Acid-base boundaries of existence of the compounds were estimated, products of conversion were identified, and solubility of MII(AsUO6)2·nH2O was determined. On the basis of the obtained data the solubility products and Gibbs functions of formation of uranoarsenates, and the solubility curves were calculated, phase diagrams of uranium(VI) and arsenic(V) in solutions and in equilibrium solid phases were constructed with the use of the equilibrium thermodynamics technique.",
Arsenic,628508,"Arsenite induces apoptosis in Chinese hamster ovary cells by generation of reactive oxygen species Abstract: Arsenic, a human carcinogen, possesses a serious environmental threat but the mechanism of its toxicity remains unclear. Knowledge of how arsenic induces cell death and how cells escape the death path may help to understand arsenic carcinogenesis. We have investigated the nature of sodium arsenite-induced cell death in Chinese hamster ovary K1 cells. Following phosphate-citric acid buffer extraction, apoptotic cells with lower DNA content than the G1 cells were detected by flow cytometry. Immediately after 4 h of 40 microM arsenite treatment, no appreciable fraction of cells with sub-G1 DNA content was detected; however, the sub-G1 cell fraction increased with postarsenite incubation time, and detectable increase started at 8 h of incubation, whereas the intracellular peroxide level as measured by the fluorescent intensity of 2',7'-dichlorofluorescein increased immediately following a 4-h arsenite treatment. Simultaneous treatment with arsenite plus antioxidant (N-acetyl-cysteine, Trolox, and Tempo); copper ion chelator (neocuproine); protein kinase inhibitor (H-7) or protein synthesis inhibitor (cycloheximide) reduced the fraction of sub-G1 cell and internucleosomal DNA degradation. Trolox, neocuproine, or cycloheximide given after arsenite treatment also effectively reduced apoptosis. These results lead to a working hypothesis that arsenite-induced apoptosis in CHO-K1 cells is triggered by the generation of hydrogen peroxide, followed by a copper-mediated Fenton reaction that catalyzes the production of hydroxyl radicals, which selectively activates protein kinase through de novo synthesis of macromolecules.",
Arsenic,627339,"A novel S-adenosyl-L-methionine:Arsenic(III) methyltransferase from rat liver cytosol Abstract: S-Adenosyl-l-methionine (AdoMet):arsenic(III) methyltransferase, purified from liver cytosol of adult male Fischer 344 rats, catalyzes transfer of a methyl group from AdoMet to trivalent arsenicals producing methylated and dimethylated arsenicals. The kinetics of production of methylated arsenicals in reaction mixtures containing enzyme, AdoMet, dithiothreitol, glutathione (GSH), and arsenite are consistent with a scheme in which monomethylated arsenical produced from arsenite is the substrate for a second methylation reaction that yields dimethylated arsenical. The mRNA for this protein predicts a 369-amino acid residue protein (molecular mass 41056) that contains common methyltransferase sequence motifs. Its sequence is similar to Cyt19, a putative methyltransferase, expressed in human and mouse tissues. Reverse transcription-polymerase chain reaction detects S-adenosyl-l-methionine:arsenic(III) methyltransferase mRNA in rat tissues and in HepG2 cells, a human cell line that methylates arsenite and methylarsonous acid. S-Adenosyl-l-methionine:arsenic(III) methyltransferase mRNA is not detected in UROtsa cells, an immortalized human urothelial cell line that does not methylate arsenite. Because methylation of arsenic is a critical feature of its metabolism, characterization of this enzyme will improve our understanding of this metalloid's metabolism and its actions as a toxin and a carcinogen.",
Arsenic,627394,"Lung cancer in a U.S. population with low to moderate arsenic exposure Abstract: BACKGROUND: Little is known about the carcinogenic potential of arsenic in areas with low to moderate concentrations of arsenic (< 100 microg/L) in drinking water. OBJECTIVES: We examined associations between arsenic and lung cancer. METHODS: A population-based case-control study of primary incident lung cancer was conducted in 10 counties in two U.S. states, New Hampshire and Vermont. The study included 223 lung cancer cases and 238 controls, each of whom provided toenail clippings for arsenic exposure measurement by inductively coupled-plasma mass spectrometry. We estimated odds ratios (ORs) of the association between arsenic exposure and lung cancer using unconditional logistic regression with adjustment for potential confounders (age, sex, race/ethnicity, smoking pack-years, education, body mass index, fish servings per week, and toenail selenium level). RESULTS: Arsenic exposure was associated with small-cell and squamous-cell carcinoma of the lung [OR = 2.75; 95% confidence interval (CI), 1.00-7.57] for toenail arsenic concentration > or = 0.114 microg/g, versus < 0.05 microg/g. A history of lung disease (bronchitis, chronic obstructive pulmonary disease, or fibrosis) was positively associated with lung cancer (OR = 2.86; 95% CI, 1.39-5.91). We also observed an elevated risk of lung cancer among participants with a history of lung disease and toenail arsenic > or = 0.05 microg/g (OR = 4.78; 95% CI, 1.87-12.2) than among individuals with low toenail arsenic and no history of lung disease. CONCLUSION: Although this study supports the possibility of an increased risk of specific lung cancer histologic types at lower levels of arsenic exposure, we recommend large-scale population-based studies.",
Arsenic,1018063,"Arsenic-induced myocardial injury: protective role of Corchorus olitorius leaves Abstract: Groundwater arsenic contamination in Bangladesh and its adjoining part of West Bengal (India) is reported to be the biggest arsenic calamity in the world in terms of the affected population. Tossa jute, Corchorus olitorius is a popular crop of this arsenic prone population. The present study was undertaken to evaluate the protective effect of aqueous extract of C. olitorius leaves (AECO) against sodium arsenite (NaAsO(2)) induced cardiotoxicity in experimental rats. The animals exposed to NaAsO(2) (10mg/kg, p.o.) for 10days exhibited a significant inhibition (p&lt;0.01) of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase and reduced glutathione level in myocardial tissues of rats. In addition, it significantly increased (p&lt;0.01) oxidized glutathione, malondialdehyde and protein carbonyl content in myocardial tissue. Treatment with AECO (50 and 100mg/kg, p.o.) for 15days prior to NaAsO(2)-intoxication significantly protected cardiac tissue against arsenic-induced oxidative impairment. In addition, AECO pretreatment significantly prevented NaAsO(2) induced hyperlipidemia, cardiac arsenic content and DNA fragmentation in experimental rats. Histological studies of myocardial tissue supported the protective activity of the AECO. The results concluded that the treatment with AECO prior to arsenic intoxication has significant protecting effect against arsenic-induced myocardial injury.",
Arsenic,2149272,Fractionation and mobility of metals in bauxite red mud Abstract: ,
Arsenic,735069,"Arsenic-induced malignant transformation of human keratinocytes: Involvement of Nrf2 Abstract: Arsenic is a well-known human skin carcinogen but the underlying mechanisms of carcinogenesis are unclear. Transcription factor Nrf2-mediated antioxidant response represents a critical cellular defense mechanism, and emerging data suggest that constitutive activation of Nrf2 contributes to malignant phenotype. In the present study when an immortalized, non-tumorigenic human keratinocyte cell line (HaCaT) was continuously exposed to environmentally relevant level of inorganic arsenite (100 nM) for 28 weeks, malignant transformation occurred as evidenced by the formation of highly aggressive squamous cell carcinoma after inoculation into nude mice. To investigate the mechanisms involved, a broad array of biomarkers for transformation were assessed in these arsenic-transformed cells (termed As-TM). In addition to increased secretion of matrix metalloproteinase-9 (MMP-9), a set of markers for squamous differentiation and skin keratinization, including keratin-1, keratin-10, involucrin, and loricrin, were significantly elevated in As-TM cells. Furthermore, As-TM cells showed increased intracellular glutathione, elevated expression of Nrf2 and its target genes, as well as generalized apoptotic resistance. In contrast to increased basal Nrf2 activity in As-TM cells, a diminished Nrf2-mediated antioxidant response induced by acute exposure to high dose of arsenite or tert-butyl hydroxyquinone occurred. The findings that multiple biomarkers for malignant transformation observed in As-TM cells, including MMP-9 and cytokeratins, are potentially regulated by Nrf2 suggest constitutive Nrf2 activation may be involved in arsenic carcinogenesis of skin. The weakened Nrf2 activation in response to oxidative stressors observed in As-TM cells, coupled with acquired apoptotic resistance, would potentially have increased the likelihood of transmittable oxidative DNA damage and fixation of mutational/DNA damage events.",
Arsenic,1070384,"Association between arsenic exposure from drinking water and plasma levels of cardiovascular markers Abstract: The authors conducted a cross-sectional study to assess the relation between arsenic exposure from drinking water and plasma levels of markers of systemic inflammation and endothelial dysfunction (matrix metalloproteinase-9, myeloperoxidase, plasminogen activator inhibitor-1, soluble E-selectin, soluble intercellular adhesion molecule-1 (ICAM-1), and soluble vascular adhesion molecule-1 (VCAM-1)) using baseline data from 668 participants (age, >30 years) in the Health Effects of Arsenic Longitudinal Study in Bangladesh (2007-2008). Both well water arsenic and urinary arsenic were positively associated with plasma levels of soluble VCAM-1. For every 1-unit increase in log-transformed well water arsenic (ln ?g/L) and urinary arsenic (ln ?g/g creatinine), plasma soluble VCAM-1 was 1.02 (95% confidence interval: 1.01, 1.03) and 1.04 (95% confidence interval: 1.01, 1.07) times greater, respectively. There was a significant interaction between arsenic exposure and higher body mass index, such that the increased levels of plasminogen activator inhibitor-1 and soluble VCAM-1 associated with arsenic exposure were stronger among people with higher body mass index. The findings indicate an effect of chronic arsenic exposure from drinking water on vascular inflammation and endothelial dysfunction that could be modified by body mass index and also suggest a potential mechanism underlying the association between arsenic exposure and cardiovascular disease.",
Arsenic,1579351,"Bacterial metabolism of environmental arsenic-mechanisms and biotechnological applications Abstract: Arsenic causes threats for environmental and human health in numerous places around the world mainly due to its carcinogenic potential at low doses. Removing arsenic from contaminated sites is hampered by the occurrence of several oxidation states with different physicochemical properties. The actual state of arsenic strongly depends on its environment whereby microorganisms play important roles in its geochemical cycle. Due to its toxicity, nearly all organisms possess metabolic mechanisms to resist its hazardous effects, mainly by active extrusion, but also by extracellular precipitation, chelation, and intracellular sequestration. Some microbes are even able to actively use various arsenic compounds in their metabolism, either as an electron donor or as a terminal electron acceptor for anaerobic respiration. Some microorganisms can also methylate inorganic arsenic, probably as a resistance mechanism, or demethylate organic arsenicals. Bioavailability of arsenic in water and sediments is strongly influenced by such microbial activities. Therefore, understanding microbial reactions to arsenic is of importance for the development of technologies for improved bioremediation of arsenic-contaminated waters and environments. This review gives an overview of the current knowledge on bacterial interactions with arsenic and on biotechnologies for its detoxification and removal.",
Arsenic,1032277,"A cohort study in southern China of tin miners exposed to radon and radon decay products Abstract: Several studies of underground miners have demonstrated that exposure to radioactive radon gas (more precisely, 222Rn and its short-lived decay products) at levels historically found in mines increases the risk of lung cancer. Because of small numbers of lung cancers, previous studies have had limited power to evaluate temporal and other characteristics of patterns of risk. Herein we report on a historical cohort study of male employees of the Yunnan Tin Corporation in southern China. The cohort consists of 17,143 workers with 175,143 person-years of observation and 981 lung cancer events. Eighty percent of the workers were employed underground and exposed to radon. The excess relative risk increased linearly with exposure, rising 0.6% per working level month (95% confidence interval = 0.4-0.8). In the mines, workers were also exposed to arsenic-containing dusts. Adjustment for arsenic exposure, a known lung carcinogen, reduced the effect of radon exposure to 0.2% per working level month (95% confidence interval = 0.1-0.2). The excess relative risk/working level month declined significantly with attained age and with radon exposure rate as measured by the cumulative working level month divided by duration of exposure. It also declined significantly with years from last exposure and with time since exposure, but these declines were consistent only after adjustment for arsenic exposure. In this cohort, 41% of the underground workers were first exposed when &lt; 15 y old; however, lung cancer risk did not vary consistently with age at first radon exposure. A joint analysis of radon exposure and smoking status (smoker vs. nonsmoker) rejected both an additive and a multiplicative association; the relationship was consistent with an intermediate association.",
Arsenic,69319,"Comparative in vitro effects of sodium arsenite and sodium arsenate on neuroblastoma cells Abstract: The toxic effects of arsenic at different cellular levels were assessed using two inorganic chemical species: sodium arsenite and sodium arsenate, representing the trivalent and pentavalent states of arsenic, respectively. Mouse neuroblastoma cell cultures (Neuro-2a) were exposed for 24 h, and cytotoxic effects evaluated were: cell proliferation by quantification of total protein content; cytoplasmic membrane integrity to cytosolic lactate dehydrogenase leakage; lysosomal hexosaminidase release; lactate dehydrogenase activity; mitochondrial succinate dehydrogenase activity; relative neutral red uptake by lysosomes; lysosomal hexosaminidase sphingolipid degradation activity; and acetylcholinesterase activity. As(III) was found to be five times more toxic than As(V) to neuroblastoma cell proliferation, but the relative extent of other alterations differed. Special sensitivity was detected for lactate dehydrogenase inhibition. Hexosaminidase activity was also very susceptible, being inhibited at low concentrations and stimulated at high concentrations. Less sensitive were the inhibition of cell proliferation, relative neutral red uptake, and acetylcholinesterase activity. As(III) was lysosomotropic, with secretion of hexosaminidase, but the release was decreased by As(V). Mitochondrial succinate dehydrogenase was inhibited by As(III) and stimulated by As(V). Minor sensitivity to cytoplasmic lactate dehydrogenase leakage for both compounds also shows that functional metabolic alterations produced by arsenic are more important than structural damage.",
Arsenic,736161,"Arsenic exposure during pregnancy and size at birth: A prospective cohort study in Bangladesh Abstract: The authors evaluated the association of prenatal arsenic exposure with size at birth (birth weight, birth length, head and chest circumferences). This prospective cohort study, based on 1,578 mother-infant pairs, was conducted in Matlab, Bangladesh, in 2002-2003. Arsenic exposure was assessed by analysis of arsenic in urine collected at around gestational weeks 8 and 30. The association of arsenic exposure with size at birth was assessed by linear regression analyses. In analysis over the full range of exposure (6-978 microg/L), no dose-effect association was found with birth size. However, significant negative dose effects were found with birth weight and head and chest circumferences at a low level of arsenic exposure (&lt;100 microg/L in urine). In this range of exposure, birth weight decreased by 1.68 (standard error (SE), 0.62) g for each 1-microg/L increase of arsenic in urine. For head and chest circumferences, the corresponding reductions were 0.05 (SE, 0.03) mm and 0.14 (SE, 0.03) mm per 1 microg/L, respectively. No further negative effects were shown at higher levels of arsenic exposure. The indicated negative effect on birth size at a low level of arsenic exposure warrants further investigation.",
Arsenic,1677416,"Experimental Assessment of CO2-Mineral-Toxic Ion Interactions in a Simplified Freshwater Aquifer: Implications for CO2 Leakage from Deep Geological Storage Abstract: The possible intrusion of CO2 into a given freshwater aquifer due to leakage from deep geological storage involves a decrease in pH, which has been directly associated with the remobilization of hazardous trace elements via mineral dissolution and/or via desorption processes. In an effort to evaluate the potential risks to potable water quality, the present study is devoted to experimental investigation of the effects of CO2 intrusion on the mobility of toxic ions in simplified equilibrated aquifers. We demonstrate that remobilization of trace elements by CO2 intrusion is not a universal physicochemical effect. In fact goethite and calcite, two minerals frequently found in aquifers, could successfully prevent the remobilization of adsorbed Cu(II), Cd(II), Se(IV), and As(V) if CO2 is intruded into a drinking water aquifer. Furthermore, a decrease in pH resulting from CO2 intrusion could reactivate the adsorption of Se(IV) and As(V) if goethite and calcite are sufficiently available in underground layers. Our results also suggest that adsorption of cadmium and copper could be promoted by calcite dissolution. These adsorbed ions on calcite are not remobilized when CO2 is intruded into the system, but it intensifies calcite dissolution. On the other hand, arsenite As(III) is significantly adsorbed on goethite, but is partially remobilized by CO2 intrusion.",
Arsenic,1508658,"An arsenic-nitrogen biradicaloid: synthesis, properties, and reactivity Abstract: As you like it: The first reported four-membered heterocycle [As(?-NTer)](2) , which can be referred to as a high-temperature stable biradicaloid, is formed, when a bulky substituent, such as the terphenyl group, prevents dimerization. Addition reactions of elemental sulfur and selenium as well as the double bond of CS(2) demonstrate that [As(?-NTer)](2) has radical-type behavior.",
Arsenic,2088514,"Association of inorganic arsenic exposure with type 2 diabetes mellitus: A meta-analysis Abstract: <strong>BACKGROUND: </strong>The association of long-term effects of inorganic arsenic (iAs) exposure with type 2 diabetes mellitus (T2DM) risk remains controversial.<br /><br /><strong>METHODS: </strong>A literature search was performed in PubMed, China National Knowledge Infrastructure and Web of Knowledge for relevant available articles published in English or Chinese from 1 January 1990 to 5 June 2013. Case-control, cohort or cross-sectional studies evaluating iAs and T2DM were included. The DerSimonian and Laird random effect model was adopted as the pooling method. Dose-response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression.<br /><br /><strong>RESULTS: </strong>Of the 569 articles identified through searching databases, 17 published articles with 2 243 745 participants for iAs in drinking water and 21 083 participants for total arsenic (tAs) in urine were included for this meta-analysis. The pooled relative risk with 95% CI of T2DM for the highest versus lowest category of iAs exposure level in drinking water was 1.75 (1.20 to 2.54). After removing three studies that had a strong effect on heterogeneity, the pooled relative risk was 1.23 (1.12 to 1.36). Dose-response analysis suggested T2DM risk increased by 13% (1.13 (1.00 to 1.27)) for every 100 µg/L increment of iAs in drinking water. Significant association of T2DM risk with tAs in urine was also found 1.28 (1.14 to 1.44).<br /><br /><strong>CONCLUSIONS: </strong>This meta-analysis indicates that long-term iAs exposure might be positively associated with T2DM risk.",
Arsenic,1021536,"Age adjustment in ecological studies: Using a study on arsenic ingestion and bladder cancer as an example Abstract: <strong>BACKGROUND: </strong>Despite its limitations, ecological study design is widely applied in epidemiology. In most cases, adjustment for age is necessary, but different methods may lead to different conclusions. To compare three methods of age adjustment, a study on the associations between arsenic in drinking water and incidence of bladder cancer in 243 townships in Taiwan was used as an example.<br /><br /><strong>METHODS: </strong>A total of 3068 cases of bladder cancer, including 2276 men and 792 women, were identified during a ten-year study period in the study townships. Three methods were applied to analyze the same data set on the ten-year study period. The first (Direct Method) applied direct standardization to obtain standardized incidence rate and then used it as the dependent variable in the regression analysis. The second (Indirect Method) applied indirect standardization to obtain standardized incidence ratio and then used it as the dependent variable in the regression analysis instead. The third (Variable Method) used proportions of residents in different age groups as a part of the independent variables in the multiple regression models.<br /><br /><strong>RESULTS: </strong>All three methods showed a statistically significant positive association between arsenic exposure above 0.64 mg/L and incidence of bladder cancer in men and women, but different results were observed for the other exposure categories. In addition, the risk estimates obtained by different methods for the same exposure category were all different.<br /><br /><strong>CONCLUSIONS: </strong>Using an empirical example, the current study confirmed the argument made by other researchers previously that whereas the three different methods of age adjustment may lead to different conclusions, only the third approach can obtain unbiased estimates of the risks. The third method can also generate estimates of the risk associated with each age group, but the other two are unable to evaluate the effects of age directly.",
Arsenic,8447,"Occupational and environmental risks in and around a smelter in northern Sweden VII Reanalysis and follow-up of chromosomal aberrations in workers exposed to arsenic Abstract: HEEP COPYRIGHT: BIOL ABS. A reanalysis of data on chromosomal aberrations among 33 copper smelter workers exposed to arsenic revealed no significant variations due to age, smoking habits or degree of arsenic exposure although the observed deviations were in the expected direction. The arsenic exposed workers showed significantly increased frequencies of chromosomal aberrations when compared with referents without known occupational exposure to genotoxic agents. Eight workers were studied at 3 different occasions, namely, 1976, 1978 and 1979. The levels of urinary arsenic decreased significantly between 1976 and 1978. There was also a significant decrease of chromosomal aberrations between 1976 and 1978 when group data were analyzed. Two individuals showed a significant decrease of breaks with time. One of them had changed from full time to half time work in 1977. In the follow-up study there is some evidence that decreased exposure leads to a lowered frequency of aberrations.",
Arsenic,1936188,"Procedia Earth and Plantetary Science Geochemical signature of arsenic-contaminated groundwater in Barak Valley (Assam) and surrounding areas, northeastern India Abstract: ",
Arsenic,1255516,"Treatment of mining acidic leachates with indigenous limestone, Zimapan Mexico Abstract: An experimental study to evaluate the potential of using indigenous limestones in a passive system to treat acid mine drainage, at a mining zone of Mexico was carried out. Chemical and mineralogical characteristics of four types of native rocks (KIT1, KIT2, KSS, QZ) showed distinct CaCO(3) contents. Synthetic aqueous leachates from an old tailings impoundment had a pH of 2.18, 34mg/L As, 705mg/L Fe(total), and 3975mg/L SO(4)(2-). To evaluate dissolution behavior of rocks, kinetic batch experiments with an acid Fe-rich solution were performed. Decaying kinetic constants adjusting H(+) concentration to a first order exponential process were: KIT1 (k=2.89), KIT2 (k=0.89) and KSS (k=0.47). Infrared spectrum and XRD of precipitates showed schwertmannite formation. To determine As and heavy metals (Fe, Cd, Zn, Al) removal from the synthetic leachates, batch experiments using KIT1 were developed. Arsenic decreased from 34.00mg/L to 0.04mg/L, Fe and Al were totally removed, and concentrations of Zn and Cd decreased 88% and 91% respectively. Analyses by IR and SEM-EDS indicate that co-precipitation with Fe-Hydroxides formed upon leachate interaction with limestone is the main As removal process. Chamosite, identified by XRD may participate in the removal of Al, SiO(2) and a fraction of Fe.",
Arsenic,1025951,"Retrospective exposure assessment for respirable and inhalable dust, crystalline silica and arsenic in the former German uranium mines of SAG/SDAG Wismut Abstract: <strong>OBJECTIVES: </strong>Starting shortly after the reunification of Germany and lasting up to the end of the 1990s, an extensive series of retrospective exposure investigations for the East German uranium mining industry was performed in order to provide information about the exposure situation of the miners towards respirable dust, inhalable dust, crystalline silica and heavy metals. It should provide the necessary information for legal compensation of miners with potential industrial diseases as well as for epidemiological research.<br /><br /><strong>METHODS: </strong>Extensive side-by-side measurements using original historic equipments as well as comprehensive evaluation of the time increments of specific jobs with respect to exposure relevant tasks were performed. After attributing average exposures to the tasks, shift exposures for the jobs could be calculated.<br /><br /><strong>RESULTS: </strong>By the end a comprehensive job exposure matrix for all underground jobs of the German uranium mining industry was developed for the components mentioned, including arsenic where relevant. In the early days of SAG/SDAG Wismut dust and silica exposures were extremely high with respirable dust up to 20 mg/m(3) and respirable crystalline silica well above 2 mg/m(3) as shift averages. Beginning from about the early 1960s dust control measures started to improve conditions dramatically.<br /><br /><strong>CONCLUSIONS: </strong>It is absolutely necessary to invest sufficient effort for the estimation of exposure situations of past technological environments. Especially, the situation of early mechanised mining, characterised by low ventilation, dry drilling techniques and generally lacking dust control measures was characterized by extreme shift exposures. It is important to keep these in mind when metal mining exposure in different environments is considered.",
Arsenic,1248948,"Modulation of arsenic-induced epidermal growth factor receptor pathway signalling by resveratrol Abstract: Arsenic (As) is both a human carcinogen and an effective anticancer drug. These aspects of arsenic toxicity develop as a consequence of arsenic-induced oxidative stress and modifications to signal pathway activity which alter gene expression. Resveratrol (RVL) a food antioxidant found in grapes and other fruits, exhibits anti-carcinogenic properties by reducing oxidative stress and restoring signal pathway control. This study investigated the impact of RVL on arsenite [As(III)]-induced cell signalling in HaCaT keratinocytes by assaying phosphorylation status of epidermal growth factor receptor (EGFR) signalling intermediates and measuring changes in expression of Phase II and DNA repair biomarkers. As(III) exposure produced dose-dependent toxicity which was associated with increased activation of EGFR pathway intermediates, cSrc, Rac1 and extracellular signal-regulated kinases 1 and 2 (ERK1/2). Arsenic-mediated ERK1/2 activation negatively regulated DNA polymerase beta expression and up regulated heme-oxygenase-1 at toxic concentrations. RVL treatment modulated As(III)-mediated ERK1/2 activation by shifting the balance of cSrc regulatory domain phosphorylation. These effects significantly altered the response of the EGFR pathway to growth factor-induced stimulation. Our research provides evidence that treatment with pharmacologically relevant doses of RVL influences cellular responses to As(III), largely due to RVL-mediated changes to Src and ERK1/2 activation.",
Arsenic,467930,"The role of reactive oxygen species in arsenite and monomethylarsonous acid-induced signal transduction in human bladder cells: Acute studies Abstract: Arsenicals are known to induce ROS, which can lead to DNA damage, oxidative stress, and carcinogenesis. A human urothelial cell line, UROtsa, was used to study the effects of arsenicals on the human bladder. Arsenite [As(III)] and monomethylarsonous acid [MMA(III)] induce oxidative stress in UROtsa cells after exposure to concentrations as low as 1 mu M and 50 nM, respectively. Previous research has implicated ROS as signaling molecules in the MAPK signaling pathway. As(III) and MMA(III) have been shown to increase phosphorylation of key proteins in the MAPI( signaling cascade downstream of ErbB2. Both Src phosphorylation (p-Src) and cyclooxygenase-2 (COX-2) are induced after exposure to 50 nM MMA(III) and 1 mu M As(III). These data suggest that ROS production is a plausible mechanism for the signaling alterations seen in UROtsa cells after acute arsenical exposure. To determine importance of ROS in the MAPK cascade and its downstream induction of p-Src and COX-2, specific ROS antioxidants (both enzymatic and nonenzymatic) were used concomitantly with arsenicals. COX-2 protein and mRNA was shown to be much more influenced by altering the levels of ROS in cells, particularly after MMA(III) treatment. The antioxidant enzyme superoxide dismutase (SOD) effectively blocked both As(III)-and MMA(III)- associated COX-2 induction. The generation of ROS and subsequent altered signaling did lead to changes in protein levels of SOD, which were detected after treatment with either 1 mu M As(III) or 50 nM MMA(III). These data suggest that the generation of ROS by arsenicals may be a mechanism leading to the altered cellular signaling seen after low-level arsenical exposure. (C) 2008 Elsevier Ireland Ltd. All rights reserved.",
Arsenic,1026119,"Arsenite interactions with phospholipid bilayers as molecular models for the human erythrocyte membrane Abstract: There are scanty reports concerning the effects of arsenic compounds on the structure and functions of cell membranes. With the aim to better understand the molecular mechanisms of the interaction of arsenite with cell membranes we have utilized bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. The capacity of arsenite to perturb the bilayer structures was determined by X-ray diffraction and fluorescence spectroscopy, whilst the modification of their thermotropic behaviour was followed by differential scanning calorimetry (DSC). The experiments carried out by X-ray diffraction and calorimetry clearly indicated that NaAsO(2) interacted with DMPE and modified its thermotropic behaviour. No such information has been so far reported in the literature.",
Arsenic,627405,"Arsenite-induced alterations in Ku70-deficient cells: A model to study genotoxic effects Abstract: As one of three subunits of DNA-dependent protein kinase (DNA-PK), Ku70 protein plays an important role in repair of DNA double-strand breaks (DNA DSB). To further understand the functions of Ku70 protein and the mechanisms underlying arsenite-induced genotoxic effects, the effects of Ku70 deficiency were examined. The Ku70-deficient cell line HLFK and null vector cell line HLFC were established after recombinant plasmid of Ku70 gene antisense RNA and null pEGFP-C1 vector were transferred into human embryo lung fibroblasts (HLF) cells. Experiments were undertaken to detect DNA DSB damage by neutral single-cell gel electrophoresis assay (SCGE), chromosomal alterations by micronucleus test, and cell cycle progression by flow cytometry in HLFC and HLFK cells treated with control, 1, 2.5, 5, or 10 microM sodium arsenite for 2, 4, or 24 h, respectively. Western blot analysis results showed that Ku70 protein content in HLFK cells decreased to 38% of those in HLFC cells. The median lethal concentrations (LC50) of sodium arsenite to HLFC and HLFK cells for 24 h were 27.38 microM and 21.80 microM, respectively. Results of neutral SCGE assay showed that there were concentration-dependent increases in tail length of DNA DSB, in percent of cells with DNA DSB tails, and in severity of DNA DSB damage in HLFK and HLFC cells. The increases in these indices in HLFK cells were significantly higher than those found in HLFC cells exposed to similar amounts of metal. The ability of DNA DSB to repair in HLFK cells was less than that seen in HLFC cells. Sodium arsenite produced concentration-dependent elevation in micronuclei and abnormal nuclei formation. The Ku70-deficiency enhanced the susceptibility to chromosomal alterations induced by sodium arsenite. Low concentrations of sodium arsenite induced cell arrest at G1; however, at high concentrations of metal this G1 arrest effect disappeared. These results suggested that Ku70 protein plays an important role in repair of DNA DSB damage and for maintainance of genome stability.",
Arsenic,2088496,"Arsenic induces reactive oxygen species-caused neuronal cell apoptosis through JNK/ERK-mediated mitochondria-dependent and GRP 78/CHOP-regulated pathways Abstract: Arsenic (As), a well-known high toxic metal, is an important environmental and industrial contaminant, and it induces oxidative stress, which causes many adverse health effects and diseases in humans, particularly in inorganic As (iAs) more harmful than organic As. Recently, epidemiological studies have suggested a possible relationship between iAs exposure and neurodegenerative disease development. However, the toxicological effects and underlying mechanisms of iAs-induced neuronal cell injuries are most unknown. The present study demonstrated that iAs significantly decreased cell viability and induced apoptosis in Neuro-2a cells. iAs also increased oxidative stress damage (production of malondialdehyde (MDA) and ROS, and reduction of Nrf2 and thioredoxin protein expression) and induced several features of mitochondria-dependent apoptotic signals, including: mitochondrial dysfunction, the activations of PARP and caspase cascades, and the increase in caspase-3 activity. Pretreatment with the antioxidant N-acetylcysteine (NAC) effectively reversed these iAs-induced responses. iAs also increased the phosphorylation of JNK and ERK1/2, but did not that p38-MAPK, in treated Neuro-2a cells. NAC and the specific JNK inhibitor (SP600125) and ERK1/2 inhibitor (PD98059) abrogated iAs-induced cell cytotoxicity, caspase-3/-7 activity, and JNK and ERK1/2 activation. Additionally, exposure of Neuro-2a cells to iAs triggered endoplasmic reticulum (ER) stress identified through several key molecules (GRP 78, CHOP, XBP-1, and caspase-12), which was prevented by NAC. Transfection with GRP 78- and CHOP-specific si-RNA dramatically suppressed GRP 78 and CHOP expression, respectively, and attenuated the activations of caspase-12, -7, and -3 in iAs-exposed cells. Therefore, these results indicate that iAs induces ROS causing neuronal cell death via both JNK/ERK-mediated mitochondria-dependent and GRP 78/CHOP-triggered apoptosis pathways.",
Arsenic,189562,"Sequence of exposure to cadmium and arsenic determines the extent of toxic effects in male Fischer rats Abstract: Arsenic and cadmium are both priority hazardous substances and human carcinogens. Although there is the potential for simultaneous exposure to both metals, the interactions of cadmium and arsenic are not well defined. We examined the toxicity of these metals when given alone or in alternating sequence to adult male Fischer rats. In the first study, a non-toxic dose of arsenic (22.5 micromol NaAsO2/kg, s.c.) was given 24 h before cadmium (10, 20, or 30 micromol CdCl2/kg, s.c.) and toxicity was assessed 24 h later. Arsenic pretreatment markedly reduced mortality in rats given the high dose of cadmium (9 survivors/10 treated) compared to rats given cadmium alone (2/10). Arsenic pretreatment also reduced cadmium-induced hepatotoxicity, as indicated by serum glutamic oxalacetic transaminase (SGOT) activity, and markedly reduced cadmium-induced testicular hemorrhagic necrosis. Arsenic pretreatment produced an 8-fold increase in hepatic levels of metallothionein (MT), a metal-binding protein often associated with cadmium tolerance. In the second study, a non-toxic dose of cadmium (3 micromol CdCl2/kg, s.c.) was given 24 h before arsenic (68, 79, 84, or 90 micro/mol NaAsO2/kg. s.c.) and toxicity was assessed 24 h later. Cadmium pretreatment did not alter the lethality of the high dose of arsenic and had no effect on arsenic-induced hepatotoxicity. Although cadmium pretreatment had no effect on arsenic toxicity, it produced large increases in hepatic MT (26-fold) before the arsenic challenge and greatly enhanced MT induction after the challenge. Thus, even though both arsenic and cadmium induce MT synthesis, only arsenic pretreatment protects against cadmium intoxication, and cadmium pretreatment does not effect arsenic toxicity. Thus, toxic interactions of arsenic and cadmium appear to depend on the sequence of exposure.",
Arsenic,2088505,"Arsenic in drinking water and renal cancers in rural Bangladesh Abstract: <strong>OBJECTIVES: </strong>Data on the role of arsenic in renal cancer are suggestive but inconclusive. The present analysis aimed to determine whether renal cancers were more likely in Bangladeshi villagers exposed to high arsenic concentration in well water and, if so, whether this excess was limited to transitional cell cancers (TCC) or occurred also for renal cell cancers (RCC).<br /><br /><strong>METHODS: </strong>Histology/cytology results from renal biopsies carried out at a single clinic in Dhaka, Bangladesh, from January 2008 to October 2011 were classified into four groups: RCC, TCC, other malignancy and benign. Patients aged ?18 years using hand-pumped well water were identified by questionnaire, blind to diagnosis. Arsenic concentration was estimated from British Geological Survey reports for administrative area (thana) of residence. In a case-referent design (with benign results as referents), ORs were calculated by multilevel logistic regression adjusted for confounding. Time since well installation and smoking were examined by stratification.<br /><br /><strong>RESULTS: </strong>Among 1489 cases included, 896 were RCC, 90 TCC and 503 benign. Arsenic concentration was estimated for 301 thanas with 63% of cases and 40% referents with arsenic concentration ?50 µg/L (p&lt;0.001). Risk increased monotonically with arsenic concentration ?50 µg/L for both cell types (RCC and TCC). Risk estimates were greater in thana with early well installation where risk was increased for RCC in exposure stratum 10&lt;50 µg/L (OR=2.47 95% CI 1.52 to 4.01). Stratification by 'ever smoked' confirmed the presence of risk in non-smokers.<br /><br /><strong>CONCLUSIONS: </strong>The relationship between arsenic concentration and both RCC and TCC suggests that arsenic is a causal factor in renal cancer.",
Arsenic,1597297,"Cell to organ: Physiological, immunotoxic and oxidative stress responses of Lamellidens marginalis to inorganic arsenite Abstract: The emerging pollutants in diverse habitats have created a need for basic research towards profiling the structural and functional parameters ranging from cell to organs in a diversity of species, thus enabling realistic analyses of the risks imposed by the environmental stressors. In the present study, the circulating haemocytes and digestive gland of an edible bivalve mollusc from eastern India, Lamellidens marginalis, were investigated for morphological and functional attributes under the challenge of inorganic arsenite-an up-coming threat to the natural freshwater reserves of the Indo-Gangetic flood plains. The molluscs were exposed to three sublethal concentrations of sodium arsenite under controlled laboratory conditions for a maximum time span of thirty days. The toxic exposure caused significant alteration in the haemocytometric profile. It inhibited the activities of phosphatases, transaminases and acetylcholinesterase which are iconic for assessment of the physiological homoeostasis in the haemocytes and digestive tissue. At both cellular and tissue level, immune surveillance was compromised through inhibited generation of nitric oxide, phenoloxidase and superoxide anions. Moreover, exposure to sodium arsenite promoted xenometabolic and oxidative stress in both haemocytes and digestive gland by reducing the activity of glutathione S-transferase and catalase. It inflicted inflammatory damage and promoted neplasia in the digestive tissue as evident from the histopathological observations. The findings would be crucial to gauge the impending threats from inorganic arsenite exposure to the freshwater invertebrates. Further, it creates an avenue to speculate a new model for arsenic biomonitoring.",
Arsenic,628461,"Enhanced urinary bladder and liver carcinogenesis in male CD1 mice exposed to transplacental inorganic arsenic and postnatal diethylstilbestrol or tamoxifen Abstract: Pregnant CD1 mice received 85 ppm arsenite in the drinking water from gestation day 8 to 18, groups (n = 35) of male offspring were subsequently injected on postpartum days 1 through 5 with diethylstilbestrol (DES; 2 microg/pup/day) or tamoxifen (TAM; 10 microg/pup/day), and tumor formation was assessed over 90 weeks. Arsenic alone increased hepatocellular carcinoma (14%), adenoma (23%) and total tumors (31%) compared to control (0, 2 and 2%, respectively). Arsenic alone also increased lung adenocarcinoma, adrenal cortical adenoma and renal cystic tubular hyperplasia compared to control. Compared to arsenic alone, arsenic plus DES increased liver tumor incidence in mice at risk 2.2-fold and increased liver tumor multiplicity (tumors/liver) 1.8-fold. The treatments alone did not impact urinary bladder carcinogenesis, but arsenic plus TAM significantly increased formation of urinary bladder transitional cell tumors (papilloma and carcinoma; 13%) compared to control (0%). Urinary bladder proliferative lesions (combined tumors and hyperplasia) were also increased by arsenic plus TAM (40%) or arsenic plus DES (43%) compared to control (0%) or the treatments alone. Urinary bladder proliferative lesions occurred in the absence of any evidence of uroepithelial cytotoxic lesions. Urinary bladder lesions and hepatocellular carcinoma induced by arsenic plus TAM and/or DES overexpressed estrogen receptor-alpha, indicating that aberrant estrogen signaling may have been a factor in the enhanced carcinogenic response. Thus, in male CD1 mice, gestational arsenic exposure alone induced liver adenoma and carcinoma, lung adenocarcinoma, adrenal adenoma and renal cystic hyperplasia. Furthermore, DES enhanced transplacental arsenic-induced hepatocarcinogenesis. In utero arsenic also initiated urinary bladder tumor formation when followed by postnatal TAM and uroepithelial proliferative lesions when followed by TAM or DES.",
Arsenic,628427,"Increased glycophorin A somatic cell variant frequency in arsenic-exposed patients of Guizhou, China Abstract: Exposure to arsenic through domestic burning arsenic-containing coal causes various tumors in a population of Guizhou, China. The glycophorin A (GPA) assay is a human mutation assay detecting somatic variation in erythrocytes expressing the MN blood type, and was used to assess genotoxicity of arsenic-exposed patients. Peripheral blood was collected from 18 adult healthy subjects and 40 arsenic-exposed patients in heparin-treated tubes. Erythrocytes were isolated, fixed in formalin and immuno-labeled with fluorescent antibodies against GPA, followed by flow cytometry analysis. Arsenic exposure increased the variant frequency (expressed as the number of variant red cells per 10(6) erythrocytes): NN, 3.7 in healthy subjects versus 21.2 in arsenic-exposed patients; N phi, 12.6 versus 33.1; MM, 13.1 versus 110; and M phi, 5.2 versus 20.3. The total GPA variant frequency was increased about five-fold (34.7 in healthy subjects versus 185 in arsenosis patients). Furthermore, the variant frequency was significantly higher in skin tumor-bearing patients: NN, 19.4 in arsenic-exposed non-tumor patients versus 31.5 in tumor-bearing patients; N phi, 29.5 versus 54.5; MM, 102 versus 159; M phi, 15.9 versus 45.1. Total GPA variant frequency in arsenic-exposed patients bearing skin tumors was significantly increased compared to patients without skin tumors (167 versus 290). The relationship between arsenic exposure history and GPA variant frequency was less evident. These data demonstrate that arsenic exposure is associated with mutations at the GPA locus, an effect exaggerated in patients bearing arsenic-induced skin tumors. The variant frequency of GPA could be a useful biomarker for arsenic exposure and arsenic carcinogenesis.",
Arsenic,2041459,"Plant Responses to Arsenic: the Role of Nitric Oxide Abstract: Arsenic (As) toxicity and the effects of nitric oxide (NO), supplied as sodium nitroprusside (SNP), were analyzed in Pistia stratiotes. The plants, which were grown in nutrient solution at pH 6.5, were exposed to four treatments for 24 h: control; SNP (0.1 mg L-1); As (1.5 mg L-1); and As + SNP (1.5 and 0.1 mg L-1). As accumulated primarily in the roots, indicating the low translocation factor of P. stratiotes. The As accumulation triggered a series of changes with increasing production of reactive oxygen intermediates and damage to cell membranes. The application of SNP was able to mitigate the harmful effects of As. This attenuation was probably due to the action of the SNP as an antioxidant, reducing the superoxide anion concentration, and as a signaling agent. Acting as a signal transducer, SNP increased the activity of enzymatic antioxidants (POX, CAT, and APX) in the leaves and stimulated the entire phytochelatins biosynthetic pathway in the roots (increased sulfate uptake and synthesis of amino acids, non-proteinthiols, and phytochelatins). The As also stimulated the phytochelatins biosynthesis, but this effect was limited, probably because plants exposed only to pollutant showed small increments in the sulfate uptake. Thus, NO also may be involved in gene regulation of sulfate carriers.",
Arsenic,627572,"Vascular smooth muscle dysfunction induced by monomethylarsonous acid (MMA III): A contributing factor to arsenic-associated cardiovascular diseases Abstract: While arsenic in drinking water is known to cause various cardiovascular diseases in human, exact mechanism still remains elusive. Recently, trivalent-methylated arsenicals, the metabolites of inorganic arsenic, were shown to have higher cytotoxic potential than inorganic arsenic. To study the role of these metabolites in arsenic-induced cardiovascular diseases, we investigated the effect of monomethylarsonous acid (MMA III), a major trivalent-methylated arsenical, on vasomotor tone of blood vessels. In isolated rat thoracic aorta and small mesenteric arteries, MMA III irreversibly suppressed normal vasoconstriction induced by three distinct agonists of phenylephrine (PE), serotonin and endothelin-1. Inhibition of vasoconstriction was retained in aortic rings without endothelium, suggesting that MMA III directly impaired the contractile function of vascular smooth muscle. The effect of MMA III was mediated by inhibition of PE-induced Ca2+ increase as found in confocal microscopy and fluorimeter in-lined organ chamber technique. The attenuation of Ca2+ increase was from concomitant inhibition of release from intracellular store and extracellular Ca2+ influx via L-type Ca2+ channel, which was blocked by MMA III as shown in voltage-clamp assay in Xenopus oocytes. MMA III did not affect downstream process of Ca2+, as shown in permeabilized arterial strips. In in vivo rat model, MMA III attenuated PE-induced blood pressure increase indeed, supporting the clinical relevance of these in vitro findings. In conclusion, MMA III-induced smooth muscle dysfunction through disturbance of Ca2+ regulation, which results in impaired vasoconstriction and aberrant blood pressure change. This study will provide a new insight into the role of trivalent-methylated arsenicals in arsenic-associated cardiovascular diseases.",
Arsenic,1172213,"Arsenic and other trace elements contamination in groundwater and a risk assessment study for the residents in the Kandal Province of Cambodia Abstract: Concentrations of arsenic and other trace elements in groundwater were examined at three villages (PT, POT and CHL) in the Kandal Province of Cambodia. Concentrations of arsenic in the groundwater ranged from 6.64 (in POT village) to 1543 microg/L (in PT village), with average and median concentrations of 552 and 353 microg/L, respectively. About 86% out of fifteen samples contained arsenic concentrations exceeding the WHO drinking water guidelines of 10 microg/L. Concentrations of arsenic (III) varied from 4 (in POT village) to 1334 microg/L (in PT village), with an average concentration of 470 microg/L. In addition, about 67%, 80% and 86% of the groundwater samples had higher concentrations for, respectively, barium, manganese and lead than the WHO drinking water guidelines. These results reveal that groundwater in Kandal Province is not only considerably contaminated with arsenic but also with barium, manganese and lead. A risk assessment study found that one sample (PT25) had a cumulative arsenic concentration (6758 mg) slightly higher than the threshold level (6750 mg) that could cause internal cancer in smelter workers with chronic exposure to arsenic from groundwater. High cumulative arsenic ingestion poses a health threat to the residents of Kandal Province.",
Arsenic,1019642,Arsenic induces decreased expression of beta2-adrenergic receptors in cultured keratinocytes Abstract: ,
Arsenic,2149302,"Leaching of elements from flue dust produced in copper scrap smelting process Abstract: To understand the features and leaching characteristics of copper (Cu) scrap smelting dust and its potential risk to environment and humans, three types of smelting dust were sampled and investigated. The dust samples were collected from the dust captured by cyclone collector, panel cooler, and bag house in a typical Cu scrap smelting process of a factory in Guangxi of China. Zinc (Zn), Cu and lead (Pb) were the main elements of the samples of cyclone collector dust (CCD), panel cooler dust (PCD), and bag house dust (BHD). There were less arsenic (As), Pb and Cu in CCD than PCD and BHD, and PCD contained more manganese (Mn), nickel (Ni), and iron (Fe) than BHD. The particle shapes of BHD appeared more regular than CCD and PCD, and energy dispersive X-ray spectroscopy analysis illustrated the compositions of selected surface areas of three samples. The size of particles ranged from 0.011 to 33.11m in CCD, from less than 1m to several mm in PCD, and from 0.832 to 363.078m in BHD. The main elements in leachate were Zn and Mn from CCD, Zn, cadmium (Cd) and Pb from PCD, Zn, Mn and Cd from BHD. The leaching toxicity risk of Cd, Mn, and Zn of PCD and BHD was higher than CCD.",
Arsenic,1015970,"Inorganic arsenic causes cell apoptosis in mouse cerebrum through an oxidative stress-regulated signaling pathway Abstract: Arsenic pollution is a major public health problem worldwide. Inorganic arsenic (iAs) is usually more harmful than organic ones. iAs pollution increases the risk of human diseases such as peripheral vascular disease and cancer. However, the toxicological effects of iAs in the brain are mostly unclear. Here, we investigated the toxic effects and possible mechanisms of iAs in the cerebrum of mice after exposure to iAs (0.5 and 5 ppm (mg/l) As(2)O(3), via the drinking water), which was the possible human exposed dose via the ingestion in iAs-contaminated areas, for 6 consecutive weeks. iAs dose-dependently caused an increase of LPO production in the plasma and cerebral cortex. iAs also decreased the reduced glutathione levels and the expressions of NQO1 and GPx mRNA in the cerebral cortex. These impairments in the cerebral cortex caused by iAs exposure were significantly correlated with the accumulation of As. Moreover, iAs induced the production of apoptotic cells and activation of caspase-3, up-regulation of Bax and Bak, and down-regulation of Mcl-1 in the cerebral cortex. Exposure to iAs also triggered the expression of ER stress-related genes, including GRP78, GRP94, and CHOP. Meanwhile, an increase of p38 activation and dephosphorylation of ERK1/2 were shown in the cerebral cortex as a result of iAs-exposed mice. These iAs-induced damages and apoptosis-related signals could be significantly reversed by NAC. Taken together, these results suggest that iAs-induced oxidative stress causes cellular apoptosis in the cerebrum, signaling of p38 and ERK1/2, and ER stress may be involved in iAs-induced cerebral toxicity.",1
Arsenic,1350786,"Blockade of calcium entry accelerates arsenite-mediated apoptosis in rat cerebellar granule cells Abstract: Arsenical exposure can cause defects in the central nervous system, yet the underlying cellular and molecular mechanisms are largely unknown. We have recently demonstrated that sodium arsenite induces apoptosis of cultured cortical and cerebellar neurons, suggesting that arsenite-induced neuronal apoptosis may contribute to at least some of its neurotoxic effects. Here we investigated the effect of Ca2+ on arsenite-mediated cerebellar granule neuron death. Sodium arsenite induced apoptosis in cerebellar neurons which were maintained in the presence of serum and depolarizing concentrations of potassium chloride (25 mM KCI). Under these conditions, inhibition of calcium entry by N-methyl-D-aspartate (NMDA) receptor blocker DL-aminophosphonovalerate (APV) or calcium channel antagonist nifedipine increased arsenite-induced apoptosis, while APV or nifedipine alone had little effect on cell viability. In cortical neurons or cerebellar neurons maintained at low potassium (5 mM), arsenite also induced apoptosis. However, the addition of APV or nifedipine did not alter levels of arsenite-induced apoptosis. These data suggest that arsenite-mediated apoptosis is regulated by intracellular calcium levels.",
Arsenic,1579302,"Identification of Tet45, a tetracycline efflux pump, from a poultry-litter-exposed soil isolate and persistence of tet(45) in the soil Abstract: OBJECTIVES: To characterize a tetracycline resistance (Tc(R)) determinant, closely related to the TetL efflux pump, in a Bhargavaea cecembensis strain previously isolated from a poultry-litter-impacted soil. METHODS: Genomic DNA of B. cecembensis DMV42A was shotgun cloned and expressed in Escherichia coli. Antimicrobial susceptibility testing and a [(3)H]tetracycline uptake assay were used to confirm the function of the target gene. Transferability of the gene was examined using filter matings and confirmed by PCR and sequencing. Real-time quantitative PCR was performed on soil metagenomic DNA to evaluate the prevalence of the gene in the soil from which B. cecembensis DMV42A was isolated and in more pristine local soils. RESULTS: The Tc(R) determinant from B. cecembensis DMV42A, designated Tet45, was identified as a tetracycline efflux pump sharing 78% amino acid identity with certain TetL proteins. In B. cecembensis DMV42A, tet(45) was adjacent to truncated and non-functional arsenic resistance genes with high sequence similarities to genes from staphylococcal plasmids. After filter matings, the tet(45) gene could be found in E. coli transconjugants, although the transfer mechanism was unknown. Tet45 homologues are also present in the genomes of several Bacillus cereus strains and a Bacillus thuringiensis strain. tet(45) was detected in the poultry-litter-impacted soil, and persisted at a similar level 2 years after removal of the chicken waste, although it was not detected in several more pristine soils. CONCLUSIONS: Tet45 is a tetracycline efflux pump closely related to TetL. Horizontal gene transfer may have contributed to the dissemination and persistence of tet(45) in a poultry-litter-impacted soil.",
Arsenic,1509326,"GSTO2*N142D gene polymorphism associated with hypothyroidism in Italian patients Abstract: Hypothyroidism is a multifactorial endocrinal disease characterized by abnormally low thyroid hormone production. Thyroiditis is one of the primary causes of hypothyroidism, as it is an increasing level of inflammation in the thyroid gland that could be due to a failure of the anti-inflammatory response. Glutathione S-transferases are biomarkers of inflammation and oxidative stress. These phase II enzymes play a relevant role in detoxifying xenobiotic compounds. Particular attention has been focused on GSTA1, GSTM1, GSTO2, GSTP1, and GSTT1 genes to evaluate if GST gene polymorphisms are associated with hypothyroidism. We screened a case-control population (patients with hypothyroidism n = 110, controls n = 122) to analyze GST gene polymorphisms. GST SNPs were determined using the PCR-RFLP method, while GST null polymorphisms were determined using a Multiplex PCR. In this study, we found differences in genotype distribution between hypothyroid individuals and controls only for the GSTO2*N142D polymorphism. Logistic regression analysis, after adjustment for age and sex, confirmed this positive association (OR = 4.56; 95 % CI 1.22-17.00; p = 0.009). The GSTO2 enzyme can catalyze several reactions important for countering oxidative stress: subjects with the D142 allele may have a deficiency in the antioxidant enzymatic system. A decrease in antioxidant capacity may trigger increased oxidative stress. Previous studies have highlighted the role of GST enzymes in inflammation disorders, but no data are available on their role in hypothyroidism. Our results suggest that GSTO2 could increase disease risk susceptibility and could act as a risk factor for hypothyroidism in Italian patients.",
Arsenic,627093,"Squalene inhibits sodium arsenite-induced sister chromatid exchanges and micronuclei in Chinese hamster ovary-K1 cells Abstract: Arsenic, widely distributed throughout our environment, is a well-established human carcinogen. We report here that squalene, a natural fish oil, is a potential agent in the reduction of sodium arsenite-induced sister chromatid exchange (SCE) and micronuclei in Chinese hamster ovary (CHO-K1) cells. Squalene dose-dependently inhibited sodium arsenite-induced SCE. At the highest concentration (160 microM), squalene reduced the SCE frequency from 8.85 to 6.47 SCEs per cell which is very close to the background level (5.82 SCEs per cell). Sodium arsenite dose-dependently induces micronuclei in CHO-K1 cells, and squalene at 80 microM significantly inhibits arsenite-induced micronuclei. However, squalene did not eliminate the killing effects of arsenite on the cells and only slightly decreased intracellular accumulation of arsenic.",
Arsenic,1339967,"Ultrasound assisted preparation of water in oil emulsions and their application in arsenic (V) removal from water in an emulsion liquid membrane process Abstract: Water in oil emulsions are prepared by using an ultra-sonication device and used in an emulsion liquid membrane process in order to recover arsenic (V) ions from an aqueous medium. The aim of this work is the investigation of the effect of emulsifier concentration and composition, and also sonication time on the emulsion droplet size and the extraction efficiency in order to obtain stable emulsions with small droplets that favor the extraction. Results show that ultrasonic waves reduce internal droplet size which enhances the extraction of arsenic. In addition, internal droplet size is decreased initially and then increased by increasing Span 80 concentration. On the other hand, by increasing Span 80 concentration, extraction amount is increased and then decreased. Furthermore, emulsifier blends provide more stability for the emulsion. Increasing concentration of Tween 20 as a hydrophilic emulsifier up to an optimum concentration decreases internal droplet size and increases extraction amount. By increasing sonication time up to 4 min, the internal droplet size is decreased and the extraction amount is increased. If sonication time is increased further, the internal droplet size is increased and the extraction amount is decreased.",
Arsenic,2064227,"Angiogenesis, mediated by miR-21, is involved arsenite-induced carcinogenesis Abstract: Evidence for arsenite-induced lung cancer in humans is strong, but the molecular mechanisms by which arsenite causes cancer remain to be established. Angiogenesis is a fundamental characteristic of cancer and is necessary in its multi-step progression. In this investigation, the mechanism for arsenite-induced angiogenesis was evaluated. Tumors formed from human bronchial epithelial (HBE) cells transformed by arsenite developed new blood vessels, which were prevented by the knockdown of miR-21, and cultures of human umbilical vein endothelial cells (HUVEC) exposed to arsenite developed endothelial tubes, a characteristic of angiogenesis. Also found in transformed HBE cells were up-regulation of a microRNA, miR-21, and increased levels of vascular endothelial growth factor (VEGF), which promotes angiogenesis. Down-regulation of miR-21 in these cells inhibited the arsenite-induced increases of VEGF levels. Thus, we conclude that arsenite induces tumor angiogenesis through processes mediated by miR-21.",
Arsenic,628042,"Protective effect of ascorbic acid against oxidative stress induced by inorganic arsenic in liver and kidney of rat Abstract: Ascorbic acid treatment in arsenic trioxide treated rats increased arsenic excretion, inhibited lipid peroxidation, improved GSH status, regulated GSSG turnover and also restored glutathione-S-transferases activity in liver and kidney. Suitable mechanisms leading to ascorbic acid protection have been discussed. Upregulation of GSH dependent enzymes was found to be necessary for a protective effect. Protection is finally attributed to higher GSH levels observed in the liver and kidney of ascorbic acid and inorganic arsenic treated rats. It is also concluded that ascorbic acid protection is influenced by gender dependent factors. Arsenic poisoning is a global problem now. Gender differences need to be considered while applying therapeutic measures.",
Arsenic,1327415,"Arsenite-induced Cdc25C degradation is through the KEN-box and ubiquitin-proteasome pathway Abstract: Arsenite is a known human carcinogen that induces tumorigenesis through either a genotoxic or an epigenetic mechanism. In this study, the effect of arsenite on cell cycle regulation and the mechanisms that contribute to this effect were investigated. Treatment of the cells with arsenite suppressed cell proliferation and reduced cell viability in a dose- or time-dependent manner. Analysis of cell cycle profile and cell cycle regulatory proteins indicated that arsenite arrested the cell cycle at G(2)/M phase, partially through induction of cell division cycle 25 (Cdc25) isoform C (Cdc25C) degradation via ubiquitin-proteasome pathways. Mutation of the putative KEN box within the region 151 to 157 of human Cdc25C or treatment of the cells with a peptide competitor encompassing the KEN box partially inhibited arsenite-induced ubiquitination of Cdc25C. Thus, these results indicate that the regulated ubiquitination of Cdc25C may be involved in the arsenite-induced proteolytic down-regulation of Cdc25C activity in the G(2)/M phase of the cell cycle and suggest a link between cell cycle and the carcinogenic effects of arsenite.",
Arsenic,2345686,"Bayesian importance parameter modeling of misaligned predictors: Soil metal measures related to residential history and intellectual disability in children Abstract: In this paper, we propose a novel spatial importance parameter hierarchical logistic regression modeling approach that includes measurement error from misalignment. We apply this model to study the relationship between the estimated concentration of soil metals at the residence of mothers and the development of intellectual disability (ID) in their children. The data consist of monthly computerized claims data about the prenatal experience of pregnant women living in nine areas within South Carolina and insured by Medicaid during January 1, 1996 and December 31, 2001 and the outcome of ID in their children during early childhood. We excluded mother-child pairs if the mother moved to an unknown location during pregnancy. We identified an association of the ID outcome with arsenic (As) and mercury (Hg) concentration in soil during pregnancy, controlling for infant sex, maternal race, mother's age, and gestational weeks at delivery. There is some indication that Hg has a slightly higher importance in the third and fourth months of pregnancy, while As has a more uniform effect over all the months with a suggestion of a slight increase in risk in later months.",
Arsenic,1372838,"Vascular dysmorphogenesis causes placental insufficiency and miscarraige in arsenic exposed mice Abstract: Rationale: Arsenic (As) exposure in human populations is associated with high rates of miscarriage. Our mouse model has revealed increased miscarriage rates in As exposed females associated with dysfunctional vasculogenesis in the placenta. The goal of this project is to define the molecular mechanisms for how As exposure causes miscarriage. Hypothesis: As exposure in utero alters the PLGF/VEGF regulatory pathway causing vascular dysmorphogenesis, placental insufficiency and miscarriage. Aims and Methods: 1. Determine how As exposure causes placental vascular dysmorphogenesis. Timed-pregnant mice were exposed to sodium arsenite (As III; 20 pmm) in their drinking water until E7.5. E8.5, E10.5 and E12.5. Vascular structure, function and expression of key endothelial cell proteins were examined. 2. Determine how As exposure alters expression of the placental PLGF/VEGF trophic system resulting in vascular dysmorphogenesis and instability. Human microvascular endothelial cells (HMEC) were exposed to AsIII and analyzed for alterations in their toxic response elements and subsequent interactions with regulatory pathways controlling cell death and cell proliferation. Results: AsIII exposure causes miscarriage between E7.5 and E12.5. when the placenta becomes vascularized. Histology shows irregularities in the placental vasculature. Expression of VWF other endothelial cell proteins are lost in a time dependent manner between E7.5 and E12.5 representing endothelial cell dysfunction and vascular instability. As exposure in cultured HMEC revealed a loss of viability commensurate with increased caspase and LDH expression; related to alterations in the VEGF regulatory pathway. Conclusions: These data show that As exposure causes vascular dysmorphogenesis resulting in placental insufficiency and subsequent miscarriage. Histomorphometry and gene expression data suggest that these effects are due to a loss of vascular trophism provided by the VEGF regulatory pathway.",
Arsenic,2298679,"Determination of lewisite metabolite 2-chlorovinylarsonous acid in urine by use of dispersive derivatization liquid-liquid microextraction followed by gas chromatography-mass spectrometry Abstract: The purpose of this study was to develop a sensitive and simple method, based on dispersive derivatization liquid-liquid microextraction-gas chromatography-mass spectrometry (DDLLME-GC-MS) in scanning and selected-ion-monitoring (SIM) modes, for detection of 2-chlorovinylarsonous acid (CVAA) as a hydrolysis product and urinary metabolite of lewisite in urine samples. Chloroform (65 ?L), methanol (500 ?L), and ethanedithiol (10 ?L) were used as extraction solvent, dispersive solvent, and derivatizing reagent, respectively. Critical conditions of the proposed method were optimized. The nucleophilic reactions of dithiol and monothiol compounds with CVAA were also studied using a competitive method. In view of the high affinity of trivalent arsenic for sulfhydryl groups, the interaction between CVAA and bis(2-chlorovinyl)arsonous acid (BCVAA) and free cysteine (Cys) was also investigated using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). The interference of Cys, present in human urine, with the detection of CVAA was evaluated using dithiol and monothiol chemicals as derivatization agents. The developed method provided a preconcentration factor of 250, and limits of detection of 0.015 and 0.30 ?g L(-1) in SIM and scanning modes, respectively. The calibration curves were linear over the concentration range of 1-400 ?g L(-1) in full-scan mode. The relative standard deviation (RSD) values were calculated to be 5.5 and 3.2 % at concentrations of 20 and 100 ?g L(-1), respectively. Collision-induced dissociation studies of the major electron-impact (EI) ions were performed to confirm the proposed fragment structure of CVAA-dithiols derivatives. Results indicated that the developed method for analysis of CVAA is suitable not only for verification of human exposure to lewisite, but also for quantification of CVAA in urine samples.",
Arsenic,1033272,"Hydride generation atomic absorption spectrophotometry for determination of arsenic in hair Abstract: A modified hydride generation, atomic absorption spectrophotometric (AAS) method for the analysis of total arsenic in hair has been developed to evaluate occupational exposures to arsenic. Hair samples are processed by a multi-step cleaning procedure to remove all external arsenic contamination prior to digestion in a nitric-sulfuric acid mixture. The resulting solution is diluted to volume with distilled water and subsequently analyzed by arsine generation and AAS using an argon-hydrogen entrained air flame. Recovery data indicate that the method is quantitative for the determination of arsenic with a recovery of over 90% and a detection limit of 0.02 microgram.",
Arsenic,2064145,What is required for the validation of in vitro assays for predicting contaminant relative bioavailability? Considerations and criteria Abstract: ,
Arsenic,1797857,"Improvement in iodine status of pregnant Australian women 3 years after introduction of a mandatory iodine fortification programme Abstract: <strong>INTRODUCTION: </strong>In order to address population-level mild iodine deficiency in Australia, a mandatory iodine fortification programme of salt used in bread was introduced in late 2009.<br /><br /><strong>METHODS: </strong>A before-after study was conducted to assess changes in median urinary iodine concentration (MUIC) measurements, according to supplement use, in convenience samples of pregnant women attending a public antenatal clinic in a regional area of New South Wales, Australia in 2008 (n=139), 2011 (n=147) and 2012 (n=114). Knowledge and practices related to iodine nutrition were investigated in 2012, using self-administered questionnaires.<br /><br /><strong>RESULTS: </strong>The mild iodine deficiency confirmed pre-fortification (MUIC (IQR)=87.5 (62-123.5; n=110)) has steadily improved to 145.5 ?g/L (91-252) in 2011 (n=106) and 166 (97-237) in 2012 (n=95) (sufficiency ? 150 ?g/L). However, only women taking supplements containing iodine had MUIC indicative of sufficiency in both years surveyed post fortification (2011: 178 ?g/L vs. 109 ?g/L, P&lt;0.001; 2012: 202 ?g/L vs. 124 ?g/L, P&lt;0.05). Despite bread being the vehicle for iodine fortification, dairy foods remained major contributors to total iodine intake (58%). Overall knowledge regarding health implications of iodine deficiency was poor.<br /><br /><strong>CONCLUSIONS: </strong>Iodine status of women has improved since the introduction of mandatory iodine fortification; however supplementation is indicated during pregnancy.",
Arsenic,1936190,Procedia Earth and Plantetary Science Evaluation of groundwater flow model for arsenic mobilization in the Datong Basin Abstract: ,
Arsenic,1070398,"Chronic occupational exposure to arsenic induces carcinogenic gene signaling networks and neoplastic transformation in human lung epithelial cells Abstract: Chronic arsenic exposure remains a human health risk; however a clear mode of action to understand gene signaling-driven arsenic carcinogenesis is currently lacking. This study chronically exposed human lung epithelial BEAS-2B cells to low-dose arsenic trioxide to elucidate cancer promoting gene signaling networks associated with arsenic-transformed (B-As) cells. Following a 6month exposure, exposed cells were assessed for enhanced cell proliferation, colony formation, invasion ability and in vivo tumor formation compared to control cell lines. Collected mRNA was subjected to whole genome expression microarray profiling followed by in silico Ingenuity Pathway Analysis (IPA) to identify lung carcinogenesis modes of action. B-As cells displayed significant increases in proliferation, colony formation and invasion ability compared to BEAS-2B cells. B-As injections into nude mice resulted in development of primary and secondary metastatic tumors. Arsenic exposure resulted in widespread up-regulation of genes associated with mitochondrial metabolism and increased reactive oxygen species protection suggesting mitochondrial dysfunction. Carcinogenic initiation via reactive oxygen species and epigenetic mechanisms was further supported by altered DNA repair, histone, and ROS-sensitive signaling. NF-?B, MAPK and NCOR1 signaling disrupted PPAR?/?-mediated lipid homeostasis. A 'pro-cancer' gene signaling network identified increased survival, proliferation, inflammation, metabolism, anti-apoptosis and mobility signaling. IPA-ranked signaling networks identified altered p21, EF1?, Akt, MAPK, and NF-?B signaling networks promoting genetic disorder, altered cell cycle, cancer and changes in nucleic acid and energy metabolism. In conclusion, transformed B-As cells with their whole genome expression profile provide an in vitro arsenic model for future lung cancer signaling research and data for chronic arsenic exposure risk assessment.",
Arsenic,87762,"Arsenic, mode of action at biologically plausible low doses: What are the implications for low dose cancer risk? Abstract: Arsenic is an established human carcinogen. However, there has been much controversy about the shape of the arsenic response curve, particularly at low doses. This controversy has been exacerbated by the fact that the mechanism(s) of arsenic carcinogenesis are still unclear and because there are few satisfactory animal models for arsenic-induced carcinogenesis. Recent epidemiological studies have shown that the relative risk for cancer among populations exposed to </=60 ppb As in their drinking water is often lower than the risk for the unexposed control population. We have found that treatment of human keratinocyte and fibroblast cells with 0.1 to 1 (mu)M arsenite (AsIII) also produces a low dose protective effect against oxidative stress and DNA damage. This response includes increased transcription, protein levels and enzyme activity of several base excision repair genes, including DNA polymerase beta and DNA ligase I. At higher concentrations (> 10 (mu)M), As induces down-regulation of DNA repair, oxidative DNA damage and apoptosis. This low dose adaptive (protective) response by a toxic agent is known as hormesis and is characteristic of many agents that induce oxidative stress. A mechanistic model for arsenic carcinogenesis based on these data would predict that the low dose risk for carcinogenesis should be sub-linear. The threshold dose where toxicity outweighs protection is hard to predict based on in vitro dose response data, but might be estimated if one could determine the form (metabolite) and concentration of arsenic responsible for changes in gene regulation in the target tissues.",
Arsenic,1352595,The Utility of Hedgehog Signaling Pathway Inhibition for Cancer Abstract: ,
Arsenic,1340124,"Arsenic exposure inhibits myogenesis and neurogenesis in P19 stem cells through repression of the ?-catenin signaling pathway Abstract: Epidemiological studies have correlated embryonic arsenic exposure with adverse developmental outcomes such as stillbirths, neonatal mortality, and low birth weight. Additionally, arsenic exposure reduces neuronal cell migration and maturation, and reduces skeletal muscle cell formation, alters muscle fiber subtype, and changes locomotor activity. This study used P19 mouse embryonic stem cells to examine whether arsenic exposure could alter their differentiation into skeletal muscles and neurons. When P19 cells were exposed to 0.1, 0.5, or 1.0 ?M sodium arsenite, embryoid body (EB) formation was not altered. However, arsenic suppressed their differentiation into muscles and neurons, as evidenced by morphological changes accompanied by a significant reduction in myosin heavy chain and Tuj1 expression. Real-time PCR, immunofluorescence, and immunoblotting were used to confirm that the altered differentiation was due to the repression of muscle- and neuron-specific transcription factors such as Pax3, Myf5, MyoD, myogenin, neurogenin 1, neurogenin 2, and NeuroD in the arsenite-exposed cells. The reductions in transcription factors expression appear to be caused by repressed Wnt/?-catenin signaling pathways in early embryogenesis, as evidenced by decreased ?-catenin expression in the arsenic-exposed EBs on differentiation days 2 and 5. Interestingly, the expression of Nanog, a transcription factor that maintains the pluripotency of stem cells, was increased after arsenite exposure, indicating that arsenite inhibits their differentiation but not proliferation. This study demonstrates that arsenic can perturb the embryonic differentiation process by repressing the Wnt/?-catenin signaling pathway. More importantly, this study may provide insight into how arsenic exposure affects skeletal and neuronal differentiation during embryogenesis.",
Arsenic,1015802,"Green tea extract alleviates arsenic-induced biochemical toxicity and lipid peroxidation in rats Abstract: The present work was undertaken to evaluate the protective effect of an aqueous extract of green tea (GT, Camellia sinensis) leaves against arsenic (NaAsO(2))-induced biochemical toxicity and lipid peroxidation production in experimental rats. The treatment with arsenic exhibited a significant increase in some serum hepatic and renal biochemical parameters (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total protein, albumin, bilirubin, cholesterol, urea and creatinine). But the co-administration of GT has increased the level of plasmatic concentration of biochemical parameters. Exposure of rats to arsenic caused also a significant increase in liver, kidney and testicular thiobarbituric acid reactive substances compared to control. However, the co-administration of GT was effective in reducing its level. To conclude, our data suggest that arsenic exposure enhanced an oxidative stress by disturbing the tissue antioxidant defense system, but the GT co-administration alleviates the toxicity induced by arsenic exposure.",
Arsenic,2298711,"Water Chemistry Impacts on Arsenic Mobilization from Arsenopyrite Dissolution and Secondary Mineral Precipitation: Implications for Managed Aquifer Recharge Abstract: Managed aquifer recharge (MAR) is a water reuse technique with the potential to meet growing water demands. However, MAR sites have encountered arsenic mobilization resulting from recharge operations. To combat this challenge, it is imperative to identify the mechanisms of arsenic mobilization during MAR. In this bench-scale study, arsenic mobilization from arsenopyrite (FeAsS) was characterized for conditions relevant to MAR operations. Experimentally determined activation energies for arsenic mobilization from FeAsS under aerobic conditions were 36.9 ± 2.3 kJ/mol for 10 mM sodium chloride, 40.8 ± 3.5 kJ/mol for 10 mM sodium nitrate, and 43.6 ± 5.0 kJ/mol for secondary effluent from a wastewater treatment plant. Interestingly, the sodium chloride system showed higher arsenic mobilization under aerobic conditions. In addition, secondary mineral precipitation varied among systems and further affected arsenic mobilization. For example, the wastewater system inhibited precipitation, while in the sodium chloride system, faster phase transformation of iron(III) (hydr)oxide precipitates was observed, resulting in hematite formation after 7 days. The phase transformation to hematite will result in less available surface area for arsenic attenuation. These new observations and activation energies can be useful to develop improved reactive transport models for the fate of arsenic during MAR, and develop strategies to minimize arsenic release.",
Arsenic,50003,"The mortality of lead smelter workers: an update Abstract: A followup study was conducted on the mortality rates of a group of lead (7439921) smelter workers which had been studied from 1977 through 1988. The average airborne lead concentration to which these workers had been exposed was 3.1mg/m3 and the blood levels averaged 56.3 micrograms/100 milliliters in 1976. Arsenic (7440382) exposures in this cohort were relatively low. An excess amount of kidney cancer was identified in the group, particularly at the higher exposure levels. A previously elevated rate of chronic renal disease was lessened somewhat in this followup period. Deaths from accidents and nonmalignant respiratory disease were significantly increased. When comparing the findings based on length of exposure, chronic renal disease was elevated among those with the longest exposure histories. No specific trend was noted for kidney cancer with regard either to duration of exposure or time since first exposure.",
Arsenic,8367,"Levels of arsenic in the United States food supply Abstract: At the present time, the Food and Drug Administration (FDA) accords the highest priority to mercury, lead, cadmium, arsenic, selenium, and zinc in its program on toxic elements in foods. The only regulatory levels for arsenic in foods in the U. S. are the tolerances which have been established for its residues in specified foods, resulting from the application of arsenical pesticides on food and feed crops and from animal feed additives. FDA has monitored for arsenic in its Total Diet Survey since the inception of this program. The data from this program indicate that the average daily intake for arsenic (as As(2)O(3)) has decreased from about 130 mug/day in 1968 to about 20 mug/day in 1974. Most of the arsenic is found in the meat-fish-poultry food class of the total diet. In individual foods, the highest levels were found in fish, with a mean level of about 1.5 ppm (as As(2)O(3)) in the edible portion of finfish. Much lower levels were found in all the other food types analyzed; of these, the highest levels found were a mean level of 0.08 ppm in chicken and 0.16 ppm in rice. FDA toxicologists do not believe that the average daily intake of arsenic, or its levels in the different food commodities, pose a hazard to the consumer.",
Arsenic,1378444,"EFFECT OF ARSENIC IN CAUSING CHROMOSOME CHANGES IN CULTURED MAMMALIAN CELLS Abstract: ARSENICALS ARE A KNOWN CAUSE OF SKIN AND LUNG CANCER IN HUMANS. THE EFFECT OF THESE AGENTS ON CHROMOSOMES OF HIGHER ORGANISMS IS CONTROVERSIAL. TO CLARIFY THE SITUATION FURTHER, THE INFLUENCE OF ARSENITE AND ARSENATE ON CHROMOSOME ABERRATIONS AND SISTER-CHROMATID EXCHANGE (SCE) IN CULTURED CHINESE HAMSTER OVARY (CHO) CELLS WAS INVESTIGATED. THE CELL CULTURES WERE TREATED WITH 10(-8), 10(-7), 10(-6), AND 10(-5) M OF NAASO2 (TRIVALENT) AND NA2HASO4 (PENTAVALENT) FOR 24 H AT 37 DEG C. IT WAS OBSERVED THAT BOTH ARSENITE AND ARSENATE COMPOUNDS PRODUCED A DOSE DEPENDENT INCREASE IN THE FREQUENCIES OF CHROMOSOME ABERRATIONS. THE MOST PROFOUND EFFECT WAS OBSERVED IN THE 10(-5) M OF NAASO2 WHERE AN EXCESSIVE NUMBER OF METAPHASE PLATES REVEALED POLYTENE CHROMOSOMES. THE ARSENICALS USED IN THIS STUDY ALSO ENHANCED THE RATES OF SCE BUT THE INCREASE DID NOT APPEAR TO BE DOSE DEPENDENT. ALL CONCENTRATIONS OF THE TEST CHEMICALS SHOWED ABOUT 2 FOLD INCREASE IN SCE. THESE RESULTS DEFINITELY INDICATE A LINK BETWEEN ARSENICALS AND MAMMALIAN CHROMOSOMES, HOWEVER, ADDITIONAL STUDIES ARE NEEDED TO REVEAL WHETHER TRIVALENT ARSENIC IS THE ""ULTIMATE CARCINOGENIC METABOLITE"" AS INDICATED BY OTHER INVESTIGATORS.",
Arsenic,1031376,"Skin cancer in chronic arsenicism Abstract: HEEP COPYRIGHT: BIOL ABS. In a limited area on the southwest coast of Taiwan where artesian well water with a high concentration of As has been used for more than 50 yr, a high prevalence of chronic arsenicism was observed in recent years, The total population of this endemic area is approximately 100,000. A general survey of 40,421 inhabitants of the area was made (19,269 males and 21,152 females). The overall prevalence rates for skin cancer, hyperpigmentation and keratosis were 10.6, 183.5, and 71.0/1000, respectively and for blackfoot disease (a local term), a peripheral vascular disorder resulting in gangrene of the extremities, 8.9/1000. The male-to-female ratio was 2.91:1 for skin cancer,1.1:1 for hyperpigmentation and keratosis, respecitvely and 1.99:1 for blackfoot disease. The prevalence increased steadily with age in all 4 conditions. The association of blackfoot disease with hyperpigmentation, keratosis and skin cancer was significantly higher than expected. The causal relationship between blackfoot disease and chronic arsenicism is emphasized. A total of 303 arsenical cancers in 184 patients (119 men and 65 women) were studied histologically; 143 patients (78%) were older than 50 yr. Of the 303 lesions, 57 were epidermoid carcinoma; 45, basal cell carcinoma (23 type B keratosis and 153 classic Bowen's lesions and its variants) and 25, combined forms. Bowen's variants included 10 with squamous whirls, 7 with features of seborrheic keratosis and 12 with horn formation. The combined forms were a mixture of superficial basal cell carcinoma, Bowen's lesion or its variants and Jadassohn epithelioma. Among the 45 basal cell carcinomas, 10 revealed bizarre multinucleated giant cells and nuclear atypicalities, 3 in deep and 7 in superficial layers. The cases of arsenical keratosis encountered were of both benign type A and malignant type B (intraepidermal carcinoma) forms. Among the 81 type A keratoses, 57 revealed no cellular atypy and 24, only mild changes. The fine structure in 30 classic cases of Bowen's lesion is briefly described and illustrated. A 5 yr follow-up study of 422 skin cancer patients and 344 patients with blackfoot disease was made. Standard mortality ratios were calculated for both and the causes of death analyzed.",
Arsenic,1020167,"Arsenic induces tumor necrosis factor alpha release and tumor necrosis factor receptor 1 signaling in T helper cell apoptosis Abstract: Long-term exposure to arsenic induces arsenical cancers in human beings. Arsenic has been shown to induce apoptosis in a variety of cell systems. Previous studies revealed that patients with arsenic-induced Bowen's disease showed a defective cell-mediated immunity and decreased percentages of T cell and T helper cell subpopulations in peripheral mononuclear cells. The purpose of this study was to investigate the effects of arsenic on T cell survival and function in mononuclear cells. Arsenic concentrations higher than 1 micro M induced tumor necrosis factor alpha release from mononuclear cells and caused a cytotoxic effect on T cells. When exposed to higher concentrations of arsenic, apoptosis was induced. CD4+ cells were the major apoptoic population in mononuclear cells. Tumor necrosis factor receptor 1 expression on CD4+ cells, but not Fas/FasL, was significantly enhanced by arsenic treatment compared to other mononuclear cells. Increased expressions of tumor necrosis factor receptor 1 related death domain proteins and activated caspases were observed. These findings indicate that tumor necrosis factor receptor 1 signaling is the major pathway in arsenic-induced T helper cell apoptosis.",
Arsenic,8332,"A survey of a population exposed to high concentrations of arsenic in well water in Fairbanks, Alaska Abstract: Following the discovery of high concentrations of arsenic (up to 10,000 µg/liter) In the well water of a residential area near Fairbanks, Alaska, an epidemiologic study was undertaken in September, 1976, to assess exposure, absorption, and clinical sequelae of chronic arsenic ingestion. Two hundred eleven (91%) of 232 area residents completed questionnaires relating to water consumption history and to the signs and symptoms of arsenicalism. Physical examinations were conducted, and complete blood counts performed. Urine, hair, nail, and well water samples were analyzed for arsenic content. Urine arsenic levels above 2 µg/100 ml were found in 130/198 (66%) of the study population. Hair arsenic levels above 1 µg/g occurred in 74/181 (41%), and nail arsenic levels above 4 µg/g In 49/132 (37%). In well-water drinkers, a close correlation was found between well water arsenic levels and levels of arsenic In urine (r = 0.58, p < 10–8). Mean urine arsenic levels (17.83 µg/100 ml) In persons who drank well water containing 100µg arsenic/liter were significantly greater than levels in bottled-water drinkers or In well-water drinkers exposed to <100µg arsenic/liter (mean 4.09 µg/100 ml; p < 10–10). Hair arsenic levels also correlated positively with well water arsenic levels (r = 0.43; p < 10–6), but may have reflected external contamination of hair during washing. Nail arsenic levels correlated poorly with well water arsenic exposure. Despite the chronic Increased exposure of the study population to arsenic, no clinical or hematologic abnormalities were found. Although the study did not consider long-term carcinogenic effects, based on the water level of arsenic (100 µg/liter) above which urine arsenic In drinkers Increases, the EPA standard (50 µg/liter) seems reasonable and conservative.",
Arsenic,1025855,"Effects of dimethylarsinic and dimethylarsinous acid on evoked synaptic potentials in hippocampal slices of young and adult rats Abstract: In this study, the effects of pentavalent dimethylarsinic acid ((CH(3))(2)AsO(OH); DMA(V)) and trivalent dimethylarsinous acid ((CH(3))(2)As(OH); DMA(III)) on synaptic transmission generated by the excitatory Schaffer collateral-CA1 synapse were tested in hippocampal slices of young (14-21 day-old) and adult (2-4 month-old) rats. Both compounds were applied in concentrations of 1 to 100 micromol/l. DMA(V) had no effect on the amplitudes of evoked fEPSPs or the induction of LTP recorded from the CA1 dendritic region either in adult or in young rats. However, application of DMA(III) significantly reduced the amplitudes of evoked fEPSPs in a concentration-dependent manner with a total depression following application of 100 micromol/l DMA(III) in adult and 10 micromol/l DMA(III) in young rats. Moreover, DMA(III) significantly affected the LTP-induction. Application of 10 micromol/l DMA(III) resulted in a complete failure of the postsynaptic potentiation of the fEPSP amplitudes in slices taken both from adult and young rats. The depressant effect was not reversible after a 30-min washout of the DMA(III). In slices of young rats, the depressant effects of DMA(III) were more pronounced than in those taken from adult ones. Compared to the (absent) effect of DMA(V) on synaptic transmission, the trivalent compound possesses a considerably higher neurotoxic potential.",
Arsenic,1032079,"Structural beta-cell changes and transient hyperglycemia in mice treated with compounds inducing inhibited citric acid cycle enzyme activity Abstract: An initial transient hyperglycemia was seen in mice injected with asparagine, fluoroacetate, hydroxylamine, or malonate plus methionine, whereas an initial triphasic blood glucose response and a transient &quot;secondary&quot; hyperglycemia were exhibited in those injected with hydroxylamine plus arsenite, and a delayed hypoglycemia was observed in those treated with fluoroacetate or arsenite. The glucose-induced insulin secretion was significantly decreased in isolated pancreatic islets incubated with hydroxylamine plus arsenite. Light and electron microscopy, pyroantimonate technique, and X-ray microanalysis disclosed mitochondrial damage, degeneration, and necrosis among the beta-cells in the islets of mice injected with hydroxylamine plus arsenite. Glycogen depletion and microvesicular fatty change were seen in the liver of mice treated with fluoroacetate, arsenite, or hydroxylamine plus arsenite. These observations support the view that inhibition of the activity of citric acid cycle enzymes and associated reactions in the beta-cells play a role in the induction of diabetic features.",
Arsenic,2345675,"Long-term exposure to low-level arsenic in drinking water and diabetes incidence: A prospective study of the diet, cancer and health cohort Abstract: <strong>BACKGROUND: </strong>Established causes of diabetes do not fully explain the epidemic. High level arsenic exposure has been implicated in diabetes risk but the effect of low-level arsenic exposure in drinking water remains unclear.<br /><br /><strong>OBJECTIVE: </strong>To determine if long-term exposure to low-level arsenic in drinking water in Denmark is associated with increased risk of diabetes using a large prospective cohort.<br /><br /><strong>METHODS: </strong>During 1993-1997 we recruited 57,053 persons. We followed each cohort member for diabetes occurrence from enrollment until 31 December 2006. We traced and geocoded residential addresses of the cohort members and used a geographic information system to link addresses with water supply areas. We estimated individual exposure to arsenic using all addresses from 1 January 1971 until the censoring date. Cox proportional hazards models were used to model the association between arsenic exposure and diabetes incidence, separately for two definitions of diabetes: all cases and a more strict definition, where cases of diabetes based solely on blood glucose results were excluded.<br /><br /><strong>RESULTS: </strong>Over a mean follow-up of 9.7 years of 52,931 eligible subjects, there were 4,304 (8.1%) diabetes cases in total, and 3,035 (5.8%) cases of diabetes based on a stricter definition. The adjusted incidence rate ratio's per 1 µg/L increment in arsenic levels in drinking water were (IRR = 1.03; 95% CI: 1.01, 1.06) and (IRR = 1.02; 95% CI: 0.99, 1.05) for all and strict diabetes cases, respectively.<br /><br /><strong>CONCLUSIONS: </strong>Long-term exposure to low-level arsenic in drinking water may contribute to development of diabetes.",
Arsenic,1936117,"Total arsenic, inorganic arsenic, and other elements concentrations in Italian rice grain varies with origin and type Abstract: Rice is comparatively efficient at assimilating inorganic arsenic (Asi), a class-one, non-threshold carcinogen, into its grain, being the dominant source of this element to mankind. Here it was investigated how the total arsenic (Ast) and Asi content of Italian rice grain sourced from market outlets varied by geographical origin and type. Total Cr, Cd Se, Mg, K, Zn, Ni were also quantified. Ast concentration on a variety basis ranged from means of 0.18 mg kg(-1) to 0.28 mg kg(-1), and from 0.11 mg kg(-1) to 0.28 mg kg(-1) by production region. For Asi concentration, means ranged from 0.08 mg kg(-1) to 0.11 mg kg(-1) by variety and 0.10 mg kg(-1) to 0.06 mg kg(-1) by region. There was significant geographical variation for both Ast and Asi; total Se and Ni concentration; while the total concentration of Zn, Cr, Ni and K were strongly influenced by the type of rice.",
Arsenic,1015794,"Chronic arsenicosis in goats with special reference to its exposure, excretion and deposition in an arsenic contaminated zone Abstract: Thirty goats were selected randomly from a village of Nadia district, West Bengal according to the previous reports of human being suffering from chronic arsenicosis. Environmental samples viz. drinking water, rice plants and grass used for goat and biological samples viz. blood, urine, faeces, hair and meat were collected to evaluate the arsenic status. It was found that arsenic concentration in both environmental and biological samples was significantly (p&lt;0.01) higher rather than respective samples on control zone. Bio-concentration factor (BCF) and bio-transfer factor (BTF) are indicated to evaluate the subclinical toxicity in goat as they do not exhibit clinical manifestation like human beings.",
Arsenic,1337284,"Transport Decreases the Quality of Cardiopulmonary Resuscitation During Simulated Maternal: Cardiac Arrest Abstract: BACKGROUND:The purpose of this study was to compare cardiopulmonary resuscitation (CPR) for simulated maternal cardiac arrest rendered during transport to the operating room with that rendered while stationary in the labor room. We hypothesized that the quality of CPR would deteriorate during transport.METHODS:Twenty-six teams composed of 2 providers (obstetricians, nurses, or anesthesiologists) were randomized to perform CPR on the Laerdal Resusci Anne SkillReporter(TM) mannequin during transport or while stationary. The primary outcome measure was the percentage of correctly delivered compressions, defined as compression rate ?100 beats per minute, correct sternal hand placement, compression depth ?1.5 inches (3.8 cm), and proper release. Secondary outcomes included interruptions in compressions, position of providers relative to the mannequin during the transport phase, and ventilation tidal volume.RESULTS:The median (interquartile range) percentage of correctly rendered compressions during phase II was 32% (10%-63%) in the transport group and 93% (58%-100%) in the stationary group (P = 0.002, 95% confidence interval of mean difference = 22%-58%). The median (interquartile range) compression rates were 124 (110-140) beats per minute in the transport group and 123 (115-132) beats per minute in the stationary group (P = 0.531). Interruptions in CPR were observed in 92% of transport and 7% of stationary drills (P &lt; 0.001, 95% confidence interval of difference = 61%-92%). During transport, 18 providers kneeled next to the mannequin, 2 straddled the mannequin, and 4 ran alongside the gurney. Median (interquartile range) tidal volume was 270 (166-430) mL in the transport group and 390 (232-513) mL in the stationary group (P = 0.03).CONCLUSIONS:Our data confirm our hypothesis and demonstrate that transport negatively affects the overall quality of resuscitation on a mannequin during simulated maternal arrest. These findings, together with previously published data on transport-related delays when moving from the labor room to the operating room further strengthen recommendations that perimortem cesarean delivery should be performed at the site of maternal cardiac arrest.",
Arsenic,711006,"Pattern of expression of apoptosis and inflammatory genes in humans exposed to arsenic and/or fluoride Abstract: We have assessed whether the combined exposure to arsenic (As) and fluoride (F) exerts a different effect than the exposure to As alone on the pattern of expression of apoptosis and inflammatory genes by immune cells. RNA was extracted from peripheral blood mononuclear cells from twenty individuals exposed or not to As or F or both. Then, cDNA was isolated, and the expression of 180 genes related to apoptosis and inflammation was tested by a cDNA array test. We found significant differences in the expression of 9 apoptosis and 15 inflammation genes in the three exposed groups compared to non-exposed individuals. In addition, subjects exposed to As or F or both showed different patterns of expression of at least 19 genes. Our data indicate that the combined exposure to As and F has a different effect on gene expression than the exposure to As or F alone.",
Arsenic,735045,"SNPs of GSTM1, T1, P1, epoxide hydrolase and DNA repair enzyme XRCC1 and risk of urinary transitional cell carcinoma in southwestern Taiwan Abstract: A hospital-based case-control study was conducted near a former black-foot disease (BFD)-endemic area in southwestern Taiwan to examine the possible risk factors and genetic susceptibility for urinary transitional cell carcinoma (TCC). A total of 221 patients with pathologically confirmed TCC and 223 age-sex-matched control subjects from urology outpatient clinics were recruited between 1998 and 2002. The results showed that residency in the BFD area and consumption of well water for more than 10 years was a strong factor on urinary cancer risk (odds ratio [OR],8.16, 95% confidence interval [CI],3.34-19.90, p<0.0001). Dose response relationship between average arsenic concentration in well water and TCC risk was also observed. Cigarette smoking played a relatively minor role in urinary carcinogenesis in this study. The GSTP1 Ile105Val A-->G polymorphism was significantly associated with cancer risk (A/G+G/G: OR=0.60, 95%CI=0.39-0.94, p=0.02), and the effect of Val105 allele was largely confined to the subjects diagnosed earlier than 55 years old (A/G+G/G: OR,0.29; 95% CI, 0.09-0.87, p=0.03). The results suggest that GSTP1 is a candidate for susceptibility locus and Ile105 allele may predispose individuals to early-onset urinary TCC. The GSTM1 null genotype was associated with tumors of high-invasiveness (OR,2.21; 95% CI, 1.34-4.73) as well as with early-onset TCC risk (OR,2.53; 95% CI, 0.97-6.59). Our preliminary results showed the XRCC1 Arg194Trp were associated with arsenic-related urinary TCC and the interaction between the genotype and the exposure was statistically significant. The modulating effect of the GSTM1, GSTT1, GSTP1 Ile105Val, EPHX Tyr113His and XRCC1 Arg280His on arsenic-related TCC risk was also suggestive. These observations implied that impaired metabolism of carcinogenic exposure as well as impaired DNA repair function play an important role in arsenic-related urinary transitional cell carcinogenesis.",
Arsenic,627210,"Bladder cancer and arsenic exposure: Differences in the two populations enrolled in a study in southwest Taiwan Abstract: Objective Analyses of bladder cancer mortality in the Black Foot Disease (BFD) endemic area of southwest Taiwan conducted by Morales et al. showed a discontinuity in risk at 400 mg/L arsenic in the drinking water in a stratified analysis and no discontinuity in a continuous analysis. As the continuous analysis presentation had been used by both the NRC and the EPA to assess the carcinogenic risk from arsenic ingestion, an explanation of the discontinuity was sought. Methods Review of 40 years of published health studies of the BFD-endemic area of SW Taiwan showed that earlier publications had limited their cancer associations with arsenic levels in artesian well waters and that the reports of Morales et al., NRC, and EPA failed to do so . Underlying data for the Morales et al. study were obtained from the appendix to the NRC report. Bladder cancer mortality rates were calculated from case counts and person-years of observation for each study village. Villages were categorized by water source according to the descriptions from the underlying study. Graphic and regression analyses were conducted of the bladder cancer mortality rates using exposure as a continuous variable and simultaneously stratifying by water source. Results The median village well arsenic levels ranged from 350 to 934 mg/L for villages solely dependent on artesian well water and from 10 to 717 mg/L for villages not solely dependent on artesian well water. Bladder cancer mortality rates were found to be dependent upon the arsenic level only for those villages that were solely dependent on artesian well water for their water source. Bladder cancer mortality rates were found to be independent of arsenic level for villages with non-artesian well water sources. Conclusions The data indicate that arsenic exposure levels do not explain the bladder cancer mortality risk in SW Taiwan among villages not dependent upon artesian well water. The association for villages dependent upon artesian well water may be explained either by arsenic acting as a high-dose carcinogen or in artesian well water as a co-carcinogen with some other aspect of artesian well water (possibly humic acid). Arsenic exposure level alone appears to be an insufficient exposure measure to describe the risk of bladder cancer mortality in the BFD-endemic area. Risk analyses that fail to take water source into account are likely to misrepresent the risk characterization, particularly at low arsenic levels.",
Arsenic,2216500,"Application of Box-Behnken design with response surface methodology for modeling and optimizing ultrasonic oxidation of arsenite with H2O2 Abstract: A combined ultrasound (US)/H2O2 process was used to oxidize arsenite to arsenate, yielding a synergistic effect value of 1.26. This showed that the combined process could be an effective method of oxidizing arsenite, instead of using either ultrasonic or H2O2 oxidation processes. This combined process was successfully modeled and optimized using a Box-Behnken design with response surface methodology (RSM). The effects of the US power density, the initial concentration of arsenite, and the H2O2 concentration on the sonochemical oxidation efficiency of arsenite were investigated. Analysis of variance indicated that the proposed quadratic model successfully interpreted the experimental data with coefficients of determination of R (2) = 0.95 and adjusted R (2) = 0.91. Through this model, we can predict and control the oxidation efficiency under different conditions. Furthermore, the optimal conditions for the oxidation of arsenite were found to be a US power density of 233.26 W L-1, an initial arsenite concentration of 0.5 mg L-1, and an H2O2 concentration of 74.29 mg L-1. The predicted oxidation efficiency obtained from the RSM under the optimal conditions was 88.95%. A confirmation test of the optimal conditions verified the validity of the model, yielding an oxidation efficiency of 90.1%.",
Arsenic,1797739,"Epithelial to mesenchymal transition in arsenic-transformed cells promotes angiogenesis through activating ?-catenin-vascular endothelial growth factor pathway Abstract: Arsenic exposure represents a major health concern increasing cancer risks, yet the mechanism of arsenic carcinogenesis has not been elucidated. We and others recently reported that cell malignant transformation by arsenic is accompanied by epithelial to mesenchymal transition (EMT). However, the role of EMT in arsenic carcinogenesis is not well understood. Although previous studies showed that short term exposure of endothelial cells to arsenic stimulated angiogenesis, it remains to be determined whether cells that were malignantly transformed by long term arsenic exposure have a pro-angiogenic effect. The objective of this study was to investigate the effect of arsenic-transformed human bronchial epithelial cells that underwent EMT on angiogenesis and the underlying mechanism. It was found that the conditioned medium from arsenic-transformed cells strongly stimulated tube formation by human umbilical vein endothelial cells (HUVECs). Moreover, enhanced angiogenesis was detected in mouse xenograft tumor tissues resulting from inoculation of arsenic-transformed cells. Mechanistic studies revealed that ?-catenin was activated in arsenic-transformed cells up-regulating its target gene expression including angiogenic-stimulating vascular endothelial growth factor (VEGF). Stably expressing microRNA-200b in arsenic-transformed cells that reversed EMT inhibited ?-catenin activation, decreased VEGF expression and reduced tube formation by HUVECs. SiRNA knockdown ?-catenin decreased VEGF expression. Adding a VEGF neutralizing antibody into the conditioned medium from arsenic-transformed cells impaired tube formation by HUVECs. Reverse transcriptase-PCR analysis revealed that the mRNA levels of canonical Wnt ligands were not increased in arsenic-transformed cells. These findings suggest that EMT in arsenic-transformed cells promotes angiogenesis through activating ?-catenin-VEGF pathway.",
Arsenic,1034271,"Case-control study of multiple myeloma and farming Abstract: A previous case-control study which utilised the occupational information available on the New Zealand Cancer Registry found an increased risk of multiple myeloma in agricultural workers consistent with previous findings in the United States. The findings are now presented for the second phase of the study which involved interviewing 76 cases of multiple myeloma (who had been included in the previous study) together with 315 controls with other types of cancer. The previous finding on an excess of farmers in the case group was confirmed by the interview data (odds ratio = 1.7, 95% confidence limits 1.0-2.9, P = 0.04). There were no significant differences between cases and controls regarding potential exposure to phenoxy herbicides or chlorophenols. There were also no significant differences regarding activities involving potential exposure to other agricultural chemicals, although the odds ratio for fencing work, which may involve exposure to arsenic and sodium pentachlorophenate, was 1.6 (95% confidence limits 0.9-2.7, P = 0.11). The odds ratios were significantly elevated for sheep farming (odds ratio = 1.9, 95% confidence limits 1.0-3.6, P = 0.04) and exposure to beef cattle (odds ratio = 1.7, 95% confidence limits 1.0-2.9, P = 0.05). The odds ratio was also elevated for persons reporting a history of hay fever (odds ratio = 1.9, 95% confidence limits 1.0-3.5, P = 0.05). Overall, these findings suggest that the search for the causes of elevated mortality in farmers from multiple myeloma should be directed to potential causes other than pesticide exposure.",
Arsenic,656841,"Dietary folate deficiency enhances induction of micronuclei by arsenic in mice Abstract: Folate deficiency increases background levels of DNA damage and can enhance the genotoxicity of chemical agents. Arsenic, a known human carcinogen present in drinking water supplies around the world, induces chromosomal and DNA damage. The effect of dietary folate deficiency on arsenic genotoxicity was evaluated using a mouse peripheral blood micronucleus (MN) assay. In duplicate experiments, male C57Bl/6J mice were fed folate-deficient or folate-sufficient diets for 7 weeks. During week 7, mice on each diet were given four consecutive daily doses of sodium arsenite (0, 2.5, 5, or 10 mg/kg) via oral gavage. Over the course of the study the folate-deficient diet produced an approximate 60% depletion of red blood cell folate. Folate deficiency by itself was associated with small but significant increases in MN in normochromatic erythrocytes (NCEs) and polychromatic erythrocytes (PCEs). Arsenic exposure was associated with significant increases in MN-PCEs in both folate-deficient and folate-sufficient mice. MN-PCE frequencies at the 10 mg/kg dose of arsenic were increased 4.5-fold over vehicle control in folate-deficient mice and 2.1-fold over control in folate-sufficient mice. At the 5 and 10 mg/kg doses of arsenic, MN-PCE levels were significantly higher (1.3-fold and 2.4-fold, respectively) in folate-deficient mice compared to folate-sufficient mice. Very few MN from either control or treated animals in either experiment exhibited kinetochore immunostaining, suggesting that the MN were derived from chromosome breakage rather than from whole chromosome loss. These results indicate that folate deficiency enhances arsenic-induced clastogenesis at doses of 5 mg/kg and higher.",
Arsenic,1019688,"Palmar spiny keratoderma associated with type IV hyperlipoproteinemia Abstract: We report the case of a 35-year-old man with acquired palmar spiny keratoderma (SK) in association with type IV hyperlipoproteinemia. Cutaneous lesions appeared 11 years before with no history of any previous skin conditions, topical medication or systemic treatment with Vitamin A-derived drugs, x-irradiation, arsenic poisoning or prolonged sun exposure. Family aggregation for SK or other disorders of keratinization was ruled out. Blood chemistries demonstrated hypertriglyceridemia (422 mg/dl) and elevation in plasma concentration of the pre-beta fraction (VLDL) of lipoproteins pattern compatible with a type IV hyperlipoproteinemia. Family aggregation for this metabolic defect was then confirmed. The histologic hallmark of the 'spine' lesion was a compact column of hyperparakeratotic cells (columnar hyperparakeratosis) continuous with a hypogranular layer, without further evidence of dyskeratotic or vacuolated keratinocytes and inflammatory cells in the corresponding dermis. SK represents a well-definite entity which fulfills precise clinico-histologic criteria. However, three main questions are related to SK: differential diagnosis with porokeratosis on histologic examination (columnar hyperparakeratosis or hyperorthokeratosis alone in SK vs. cornoid lamella accompanied by remarkable dermoepidermal changes in porokeratosis); classificative scheme (proper nomenclature to avoid misleading and confounding names); and nosological arrangement (probably two subsets exist: hereditary or benign; and acquired, or idiopathic, which may be paraneoplastic in about 50% of the patients). To the best of our knowledge this is the first case reporting the association between SK and a metabolic impairment although the real connections linking these conditions are still unclear.",
Arsenic,2088417,"Relations of arsenic concentrations among groundwater, soil and paddy from an alluvial plain of Korea Abstract: ",
Arsenic,805143,"Associations between blood metals and fecundity among women residing in New York State Abstract: Trace exposures to metals may affect female reproductive health. To assess the relation between trace concentrations of blood metals and female fecundity, 99 non-pregnant women discontinuing contraception for the purpose of becoming pregnant were prospectively followed. Participants completed a baseline interview and daily diaries until pregnant, or up to 12 menstrual cycles at risk for pregnancy; home pregnancy test kits were used. For 80 women, whole blood specimens were analyzed for arsenic, cadmium, lead, magnesium, nickel, selenium and zinc using inductively coupled plasma mass spectrometry (ICP-MS). Time to pregnancy was estimated using Cox proportional hazards models for discrete time. Metal concentrations were generally within population reference intervals. Adjusted models suggest a 51.5% increase in the probability for pregnancy per 3.60 ?g/L increase in Mg (P=0.062), and a 27.7% decrease per 0.54 ?g/L increase in Zn (P=0.114). Findings indicate that Mg and Zn may impact female fecundity, but in varying directions.",
Arsenic,2278651,"Concentrations and health risks of lead, cadmium, arsenic, and mercury in rice and edible mushrooms in China Abstract: In this study, four common heavy metals, lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in rice and edible mushrooms of China were studied to evaluate contamination level and edible safety. Ninety two (92) rice samples were collected from the main rice growing regions in China, and 38 fresh and 21 dry edible mushroom samples were collected from typical markets in Nanjing City. The analyzed metal concentrations were significantly different between rice and edible mushroom samples (p<0.05). The results showed that Pb, Cd and As contents in 4.3%, 3.3% and 2.2% rice samples respectively, were above maximum allowable concentration (MAC). In fresh edible mushroom, Pb and Hg contents in 2.6% samples were above MAC, respectively. However, only Hg content in 4.8% dry edible mushroom samples was above its MAC. Therefore, more than 95% rice and edible mushroom samples in our test had high edible safety.",
Arsenic,2064289,"Beyond the fringe: when science moves from innovative to nonsense Abstract: Microbiology has experienced examples of highly-productive researchers who have gone beyond just interpreting their experimental results with hypotheses and published nonsense that was readily recognized as such by readers. Although the most-discussed cases of this pathology come from physics, studies of single celled microbes, virology, and immunology have provided many examples. Five cases are described here along with some generalizations. These are the Lamarckian inheritance of acquired characteristics reported by distinguished and experienced researchers, vector-less DNA transfer and incorporation of bacterial DNA into chromosomes of plants years before vector construction of genetically modified plants was invented, water with memory of immunoglobulin IgE, a new electromagnetic radiation method for identifying bacterial and viral pathogens by the discoverer of HIV virus, and the claim of isolation of a new bacterial isolate with arsenic replacing phosphorus in DNA. The examples represent very dissimilar areas and the only common factor is hubris on the part of experienced researchers. Secondarily, failure of peer review sometimes happens and journal editors do not step in, sometimes even when alerted before publication,. These failures of the publishing process teach us that unnecessary mistakes occur and should warn us all to watch our own enthusiasms. This article is protected by copyright. All rights reserved.",
Arsenic,627000,"Metallothionein (I/II) suppresses genotoxicity caused by dimethylarsinic acid Abstract: Abstract. Arsenic is an environmental chemical of considerable concern due to its association with an increased risk of human cancer. Dimethy1arsinic acid (DMAA) is one of the major methylated metabolites of ingested arsenicals in most mammals. To better clarify the role of metallothionein (MT) in modifying DMAA genotoxicity, MT-I1II null mice, and the corresponding wild-type mice, were exposed to DMAA (0, 188, 375 or 750 mg/kg body weight) via a single oral dose. Twenty-four hours after the DMAA injection, there was increased formation of 8-hydroxy-2'-deoxyguanosine (8-0HdG) in serum and urine and a higher number of DNA strand breaks in peripheral blood cells. These increased levels were concomitant with increasing dose concentrations of DMAA in both strains of mice and they were significantly higher in MT-I1Il null mice than in wild-type mice. Furthermore, the induction of apoptotic cells in the urinary bladder epithelium of MT-I1II null mice was significantly higher than in dose-matched wild-type mice exposed to DMAA. On the other hand, in both liver and in the alveolar and bronchial areas of the lung, the extent of DMAA-induced apoptosis was not different between wild-type and MT-I1II null mice and was increased in both strains. In addition, the concentration of hepatic MT in wild-type mice increased in a DMAA dose-dependent manner but was undetectable-in MT-I1II null mice and could not subsequently be induced by DMAA. In conclusion, DMAA exposure causes oxidative stress, DNA damage and, specific induction of apoptosis in target organs of arsenic carcinogenesis, which may be attributable to the mechanism(s) of arsenic-induced carcinogenesis in rodents. MT exhibited some protective roles during DNA damage presumably by acting as an antioxidant.",
Arsenic,2337166,"Hepatoprotective activity of Tephrosia purpurea against arsenic induced toxicity in rats Abstract: <strong>AIM: </strong>The present study was conducted to evaluate the hepatoprotective activity of Tephrosia purpurea (TP) against sodium arsenite (NaAsO2) induced sub-acute toxicity in rats.<br /><br /><strong>MATERIALS AND METHODS: </strong>Twenty four wistar albino rats of either sex were randomly divided into three groups. Group II and III were orally administered with sodium arsenite (10 mg/kg) daily in drinking water for 28 days. Additionally Group III was orally treated with hydro-alcoholic extract of Tephrosia purpurea (TP) @ 500 mg/kg daily for the same time period, whereas only deionized water was given to Group I (control). Serum biomarker levels, oxidative stress parameters and arsenic concentration were assessed in liver. Histopathology was also conducted.<br /><br /><strong>RESULTS: </strong>It has been seen that TPE (500 mg/kg) significantly (P &lt; 0.01) reduced serum ALT, AST, ALP activity and increased total protein and reduced necrosis and inflammation in liver of group III compared to group II. A significantly (P &lt; 0.01) higher LPO and lower GSH levels without change in SOD activity in liver was also observed in group II compared to group III, though there was no significant difference in arsenic accumulation between them. The plant extract also protects the animals of group III from significant (P &lt; 0.01) reduction in body weight.<br /><br /><strong>CONCLUSION: </strong>Our study shows that supplementation of Tephrosia purpurea extract (500 mg/kg) could ameliorate the hepatotoxic action of arsenic.",
Arsenic,1018284,"Influence of arsenic stress on synthesis and localization of low-molecular-weight thiols in Pteris vittata Abstract: The roles of low-molecular-weight thiols (LMWTs), such as glutathione and phytochelatins, in arsenic (As) tolerance and hyperaccumulation in Pteris vittata an As-hyperaccumulator fern remain to be better understood. This study aimed to thoroughly characterize LMWT synthesis in P. vittata to understand the roles played by LMWTs in As tolerance and hyperaccumulation. LMWT synthesis in P. vittata was induced directly by As, and not by As-mediated oxidative stress. Expression of PvECS2, one of the putative genes of ?-glutamylcysteine synthetase (?ECS), increases in P. vittata shoots at 48h after the onset of As exposure, almost corresponding to the increase in the concentrations of ?-glutamylcysteine and glutathione. Furthermore, localization of As showed similar trends to those of LMWTs in fronds at both whole-frond and cellular levels. This study thus indicates the specific contribution of LMWTs to As tolerance in P. vittata. ?ECS may be responsible for the As-induced enhancement of LMWT synthesis.",
Arsenic,1022060,"Toxicokinetics/toxicodynamics with damage feedback improves risk assessment for tilapia and freshwater clam exposed to arsenic Abstract: It has been proposed that irreversible responses of organisms exposed to contaminants are due to a systems-level feedback. Here we tested this hypothesis by reanalyzing the published data on toxicokinetics and survival probability based on a systems-level threshold damage model (TDM) incorporating with a positive damage feedback to explore the steady-state response and dynamic behavior of damage for tilapia and freshwater clam exposed to waterborne arsenic (As). We found that ultrasensitivity appeared in As-tilapia and freshwater clam systems with Hill coefficient n ? 4, indicating that the positive damage feedback mechanism has been triggered. We confirmed that damage can trigger a positive feedback loop that together with As stressor increases irreversibility. This study also showed that TDM with positive feedback gave a much better predictability than that of TDM at As concentrations ranging from 100 to 500 mg l-1 for freshwater clam, whereas for tilapia, two models had nearly same performance on predictability. We suggested that mortality-time profile derived Hill coefficient could be used as a new risk indicator to assess the survival probability for species exposed to waterborne metals. We anticipated that the proposed toxicokinetics/toxicodynamics with a positive damage feedback may facilitate our understanding and manipulation of complex mechanisms of metal susceptibility among species and improve current risk assessment strategies.",
Arsenic,1019783,"Arsenic content in the femur head of the residents of southern and central Poland Abstract: Arsenic content was assayed in the samples of the femur head of the people living in southern and central Poland (Kraków, n=13; Silesian region, n=13; Lódz, n=12). The average age being 68.7+/-8.7 yr. Arsenic content in the femur head was determined applying the hydride generation atomic absorption spectrometry (HG-AAS) method after microwave mineralization. The average arsenic contents in the femur head of the residents of the Lódz, Kraków, and Silesian regions were 0.41 microg/g, 0.37 microg/g, and 0.18 microg/g, respectively. No correlation has been found between arsenic content in the femur head and the content of other metals. Neither the age nor sex of the people tested affected the arsenic content in the femur head.",
Arsenic,1343863,"Inhibition of translational initiation by activators of the glucose-regulated stress protein and heat shock protein stress response systems - Role of the interferon-inducible double-stranded RNA-activated eukaryotic initiation factor 2 alpha kinase Abstract: Depletion of endoplasmic reticulum (ER) Ca2+ perturbs protein folding and processing within the organelle while inhibiting translational initiation through activation of the double-stranded RNA-activated eukaryotic initiation factor (eIF)-2alpha kinase (PKR) (Prostko, C. R., Dholakia, J. N., Brostrom, M. A., and Brostrom, C. O. (1995) J. Biol. Chem. 270, 6211-6215). The glucose-regulated stress protein (GRP) chaperones are subsequently induced. We now report that sodium arsenite, a prototype for stressors fostering cytoplasmic protein misfolding, also inhibits translational initiation through activation of PKR while subsequently inducing the heat shock protein (HSP) chaperones. Arsenite neither mobilized ER-associated Ca2+ nor slowed peptide chain elongation. Various HSP-inducing chemicals caused rapid phosphorylation of eIF-2alpha. When incubated with double-stranded RNA, extracts derived from arsenite-treated cells displayed greater degrees of phosphorylation of PKR and eIF-2alpha than did control extracts. Cells overexpressing a dominant negative PKR mutation resisted translational inhibition and eIF-2alpha phosphorylation in response to ER or cytoplasmic stressors. Induction of either the HSP or GRP chaperones was accompanied by development of translational tolerance to either Ca2+-mobilizing agents or arsenite. Following induction of the HSPs by arsenite, cells remained susceptible to induction of the GRPs by Ca2+-mobilizing agents. Conversely, cells possessing induced GRP contents in response to Ca2+-mobilizing agents readily induced the HSPs in response to arsenite. It is concluded that the two chaperone systems function independently except for their mutual suppression of PKR.",
Arsenic,1343824,"Cell stress is related to re-localization of Argonaute 2 and to decreased RNA interference in human cells Abstract: Various kinds of stress on human cells induce the formation of endogenous stress granules (SGs). Human Argonaute 2 (hAgo2), the catalytic core component of the RNA-induced silencing complex (RISC), can be recruited to SGs as well as P-bodies (PBs) indicating that the dynamic intracellular distribution of hAgo2 in SGs, in PBs or at other sub-cellular sites could be related to the efficiency of the RNA interference (RNAi) machinery. Here, we studied the influence of heat shock, sodium arsenite (NaAsO2), cycloheximide (CHX) and Lipofectamine 2000-mediated transfection of phosphorothioate (PS)-modified oligonucleotides (ON) on the intracellular localization of hAgo2 and the efficiency of RNAi. Fluorescence microscopy and sedimentation analysis of cell fractions indicate stress-induced accumulation of hAgo2 in SGs and the loss of distinctly composed complexes containing hAgo2 or their sub-cellular context. Transfection of cells with PS-ON induces cell stress that is phenotypically similar to the established inducers heat shock and NaAsO2. The intracellular re-distribution of hAgo2 is related to its increased metabolic stability and to decreased RNAi directed by microRNA or by short interfering RNA. Here, we propose a functional model of the relationship between cell stress, translocation of hAgo2 to SGs providing a depot function, and loss of RNAi activity.",
Arsenic,729432,"Identification of aneuploidy-inducing agents using cytokinesis-blocked human lymphocytes and an antikinetochore antibody Abstract: The identification of agents causing aneuploidy in humans, a condition associated with carcinogenesis and birth defects, is currently limited due to the highly skilled and time-consuming nature of cytogenetic analyses. We report the development of a new simple and rapid assay to identify aneuploidy-inducing agents (aneuploidogens). The assay involves the chemical- or radiation-induced formation of micronuclei in cytokinesis-blocked human lymphocytes and the use of an antikinetochore antibody to determine whether the micronuclei contain centromeres--a condition indicating a high potential for aneuploidy. All agents tested produced dose-related increases in the frequency of micronucleated cells. The micronucleated cells induced by the known aneuploidogens--colchicine, vincristine sulfate, and diethylstilbestrol--contained kinetochore-positive micronuclei 92, 87, and 76% of the time, respectively. In contrast, the micronucleated cells induced by the potent clastogens--ionizing radiation and sodium arsenite--contained kinetochore-positive micronuclei only 3 and 19% of the time, respectively. These results indicate that this relatively simple assay can discriminate between aneuploidogens and clastogens and may allow a more rapid identification of environmental and therapeutic agents with aneuploidy-inducing potential.",
Arsenic,1328415,"Genes associated with pro-apoptotic and protective mechanisms are affected differently on exposure of neuronal cell cultures to arsenite. No indication for endoplasmic reticulum stress despite activation of grp78 and gadd153 expression Abstract: The effect of arsenite exposure on cell viability, protein synthesis, energy metabolism and the expression of genes coding for cytoplasmic (hsp70) and endoplasmic reticulum (ER; gadd153, grp78, grp94) stress proteins was investigated in primary neuronal cell cultures. Furthermore, signs of ER stress were evaluated by investigating xbp1 mRNA processing. Arsenite levels of 30 and 100 microM induced severe cell injury. Protein synthesis was reduced to below 20% of control in cultures exposed to 30 and 100 microM arsenite for 1 h, and it remained markedly suppressed until 24 h of exposure. Arsenite induced a transient inhibition of energy metabolism after 1 h of exposure, but energy state recovered completely after 3 h. Arsenite exposure affected the expression and translation of genes coding for HSP70 and GRP78, GRP94, GADD153 to different extents. While hsp70 mRNA levels rose drastically, approximally 550-fold after 6 h exposure, HSP70 protein levels did not change over the first 6 h. On the other hand, gadd153 mRNA levels rose only approximately 14-fold after 6 h exposure, while GADD153 protein levels were markedly increased after 3 and 6 h exposure. HSP70 protein levels were markedly increased and GADD153 protein levels decreased to almost control levels in cultures left in arsenite solution for 24 h, i.e. when only a small fraction of cells had escaped arsenite toxicity. Arsenite exposure of neurons thus induced an imbalance between pro-apoptotic and survival-activating pathways. Despite the marked increase in gadd153 mRNA levels, we did not observe signs of xbp1 processing in arsenite exposed cultures, indicating that arsenite did not produce ER stress.",
Arsenic,1070356,"Occurrence and geochemical behavior of arsenic in a coastal aquifer-aquitard system of the Pearl River Delta, China Abstract: Elevated concentrations of arsenic, up to 161?g/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer-aquitard system.",
Arsenic,2337115,"Accumulation of uranium by aquatic plants in field conditions: Prospects for phytoremediation Abstract: A study was undertaken to determine Uranium concentrations in water and aquatic plants in the uraniferous region of Beiras, Central Portugal. Samples were collected from running water (n = 200) at places where aquatic species were observed. Plant samples were collected from 28 species of submerged, free-floating and rooted emergent plants including 2 bryophytes and 1 pteridophyte. Uranium concentrations in surface waters ranged from 0.23 to 1217 mu g L-1. The aquatic plant species studied, including several previously untested species, exhibited the ability to accumulate U in concentrations many times that of the ambient water. In general submerged plants exhibited higher U content followed by rooted emergent and free floating species. The highest U concentrations were observed in the bryophyte Fontinalis antipyretica (up to 4979 mg kg(-1)) followed by Callitriche stagnalis (1963 mg kg(-1)), Callitriche hamulata (379 mg kg(-1)), Ranunculus peltatus subsp. saniculifolius (243 mg kg(-1)), Callitriche lusitanica (218 mg kg(-1)), and Ranunculus trichophyllus (65.8 mg kg(-1)). In two out of three rooted emergent species U seemed to be preferentially partitioned in rhizome/roots with highest rhizome U content recorded in Typha latifolia (380 mg kg(-1)). Among the free-floating species, the highest U content (42.5 mg kg(-1)) was seen in Lemna minor. The bryophyte F. antipyretica and Callitrichaceae members seem to be promising candidates for the development of phytofiltration methodologies based on U accumulation, abundance and biomass production. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,2337192,"Does the metal content in soil around a pregnant woman's home increase the risk of low birth weight for her infant? Abstract: Low birth weight (LBW) is associated with a number of maternal environmental exposures during pregnancy. This study explored the association between soil metal concentrations around the home where the mother lived during pregnancy and the outcome of LBW. We used a retrospective cohort of 9,920 mother-child pairs who were insured by Medicaid during pregnancy and lived in ten residential areas, where we conducted soil sampling. We used a grid that overlaid the residential areas and collected soil samples at the grid intersections. The soil was analyzed for the concentration of eight metals [arsenic (As), barium (Ba), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), and mercury (Hg)], and we then used Bayesian Kriging to estimate the concentration at the actual maternal addresses, since we had the GIS coordinates of the homes. We used generalized additive modeling, because the metal concentrations had nonlinear associations with LBW, to develop the best fitting multivariable model for estimating the risk of LBW. The final model showed significant associations for female infants, maternal smoking during pregnancy, non-white mothers, Cu, and As with LBW. The As variable was nonlinear in relation to LBW, and the association between higher concentrations of As with LBW was strong (p = 0.002). We identified a statistically significant association between soil concentrations of arsenic around the home of pregnant women and an increased risk of LBW for her infant.",
Arsenic,1519218,"COMPARATIVE STUDY OF Cu, As AND Sb TOXICITY BETWEEN DUMP-FIELDS OF ABANDONED Cu-DEPOSITS L'UBIETOVA AND SPANIA DOLINA (CENTRAL SLOVAKIA) Abstract: ",
Arsenic,1345852,The Chinese Herb Isolate Isorhapontigenin Induces Apoptosis in Human Cancer Cells by Down-regulating Overexpression of Antiapoptotic Protein XIAP Abstract: ,
Arsenic,656907,"Effects of co-administration of dietary sodium arsenite and an NADPH oxidase inhibitor on the rat bladder epithelium Abstract: Arsenite (As(III)), an inorganic arsenical, is a known human carcinogen, inducing tumors of the skin, urinary bladder and lung. It is metabolized to organic methylated arsenicals. Oxidative stress has been suggested as a mechanism for arsenic-induced carcinogenesis. Reactive oxygen species (ROS) can be important factors for carcinogenesis and tumor progression. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is known to produce intracellular ROS, therefore, we investigated the ability of apocynin (acetovanillone), an NADPH oxidase inhibitor, to inhibit the cytotoxicity and regenerative cell proliferation of arsenic in vitro and in vivo. Apocynin had similar effects in reducing the cytotoxicity of As(III) and dimethylarsinous acid (DMA(III)) in rat urothelial cells in vitro. When tested at the same concentrations as apocynin, other antioxidants, such as l-ascorbate and N-acetylcysteine, did not inhibit As(III)-induced cytotoxicity but they were more effective at inhibiting DMA(III)-induced cytotoxicity compared with apocynin. In vivo, female rats were treated for 3 weeks with 100ppm As(III). Immunohistochemical staining for 8-hydroxy-2'-deoxyguanosine (8-OHdG) showed that apocynin reduced oxidative stress partially induced by As(III) treatment on rat urothelium, and significantly reduced the cytotoxicity of superficial cells detected by scanning electron microscopy (SEM). However, based on the incidence of simple hyperplasia and the bromodeoxyuridine (BrdU) labeling index, apocynin did not inhibit As(III)-induced urothelial cell proliferation. These data suggest that the NADPH oxidase inhibitor, apocynin, may have the ability to partially inhibit arsenic-induced oxidative stress and cytotoxicity of the rat bladder epithelium in vitro and in vivo. However, apocynin did not inhibit the regenerative cell proliferation induced by arsenite in a short-term study.",
Arsenic,628806,"Nonmalignant respiratory effects of chronic arsenic exposure from drinking water among never-smokers in Bangladesh Abstract: BACKGROUND: Arsenic from drinking water has been associated with malignant and nonmalignant respiratory illnesses. The association with nonmalignant respiratory illnesses has not been well established because the assessments of respiratory symptoms may be influenced by recall bias or interviewer bias because participants had visible skin lesions. OBJECTIVES: We examined the relationship of the serum level of Clara cell protein CC16--a novel biomarker for respiratory illnesses--with well As, total urinary As, and urinary As methylation indices. METHODS: We conducted a cross-sectional study in nonsmoking individuals (n = 241) selected from a large cohort with a wide range of As exposure (0.1-761 microg/L) from drinking water in Bangladesh. Total urinary As, urinary As metabolites, and serum CC16 were measured in urine and serum samples collected at baseline of the parent cohort study. RESULTS: We observed an inverse association between urinary As and serum CC16 among persons with skin lesions (beta = -0.13, p = 0.01). We also observed a positive association between secondary methylation index in urinary As and CC16 levels (beta = 0.12, p = 0.05) in the overall study population; the association was stronger among people without skin lesions (beta = 0.18, p = 0.04), indicating that increased methylation capability may be protective against As-induced respiratory damage. In a subsample of study participants undergoing spirometric measures (n = 31), we observed inverse associations between urinary As and predictive FEV(1) (forced expiratory volume measured in 1 sec) (r = -0.37; FEV(1)/forced vital capacity ratio and primary methylation index (r = -0.42, p = 0.01). CONCLUSIONS: The findings suggest that serum CC16 may be a useful biomarker of epithelial lung damage in individuals with arsenical skin lesions. Also, we observed the deleterious respiratory effects of As exposure at concentrations lower than reported in earlier studies.",
Arsenic,1508568,"Elemental composition of dog foods using nitric acid and simulated gastric digestions Abstract: Eighteen dry dog foods obtained commercially in the United States were digested using microwave assisted nitric acid digestion and a simulated gastric digestion. Digests were analysed for 23 elements using inductively coupled plasma-mass spectrometry. Data, expressed as dry matter concentrations, were compared to published nitric acid digestion results. Nitric acid data obtained in the present study were not statistically different from published data, with the exception of Mo, Sn, Sb, Tl and Th. However, significant differences in individual intra-sample results were observed between published studies and the present work. Simulated gastric digestions demonstrated lower extraction efficiencies (&lt;50% nitric acid digestions) that were statistically significant. Much lower bioavailability was observed for Al, Ba and Pb. In general, elemental concentrations were determined to be lower than the appropriate Mineral Tolerance Limit or consistent with background concentrations in foodstuffs. Evaluation against Reference Doses (RfDs) showed concentrations for many elements obtained by nitric acid digestion to be above RfD levels. However, the respective simulated gastric digestion data were below or only moderately elevated above RfDs. Only arsenic displayed median and maximum concentrations at factors of five and ten above the relevant RfD.",
Arsenic,732013,"Arsenite induces delayed mutagenesis and transformation in human osteosarcoma cells at extremely low concentrations Abstract: Arsenite is a human multisite carcinogen, but its mechanism of action is not known. We recently found that extremely low concentrations (</=0.1 microM) of arsenite transform human osteosarcoma TE85 (HOS) cells to anchorage-independence. In contrast to other carcinogens which transform these cells within days of exposure, almost 8 weeks of arsenite exposure are required for transformation. We decided to reexamine the question of arsenite mutagenicity using chronic exposure in a spontaneous mutagenesis assay we previously developed. Arsenite was able to cause a delayed increase in mutagenesis at extremely low concentrations (</=0.1 microM) in a dose-dependent manner. The increase in mutant frequency occurred after almost 20 generations of growth in arsenite. Transformation required more than 30 generations of continuous exposure. We also found that arsenite induced gene amplification of the dihydrofolate reductase (DHFR) gene in a dose-dependent manner. Since HOS cells are able to methylate arsenite at a very low rate, it was possible that active metabolites such as monomethylarsonous acid (MMA(III)) contributed to the delayed mutagenesis and transformation in these cells. However, when the assay was repeated with MMA(III), we found no significant increase in mutagenesis or transformation, suggesting that arsenite-induced delayed mutagenesis and transformation are not caused by arsenite's metabolites, but by arsenite itself. Our results suggest that long-term exposure to low concentrations of arsenite may affect signaling pathways that result in a progressive genomic instability.",
Arsenic,1019862,"Arsenite-induced nitric oxide generation is cell cycle-dependent and aberrant in NBS cells Abstract: Exposure to arsenic has been reported to cause DNA damage and eventually the occurrence of bladder, lung and skin cancers. A previous report has demonstrated that arsenite-induced phosphorylation of Mre11, a protein involved in the repair of DNA double strand breaks (DSBs), is M phase-dependent and requires the Nijmegen breakage syndrome (NBS) protein, NBS1 [DNA Repair 1 (2002) 137]. Furthermore, arsenite treatment arrests cells at the M phase and the cells eventually go through apoptosis [Biochemical Pharmacology 60 (2000) 771]. Here we demonstrate that arsenite treatment enhances the generation of nitric oxide (NO), and that the enhanced NO generation is dominant at the G2/M phase. Arsenite-induced NO generation is impaired in DSB repair-defective NBS cells, but not in NBS1-reconstituted NBS cells, suggesting NBS1 is required for effective NO generation. In summary, our study showed, for the first time, that arsenite-induced NO generation is cell-cycle- and NBS1-dependent.",
Arsenic,2278973,"Selenium(IV) uptake by maghemite (?-Fe2O3) Abstract: The mechanism of selenium(IV) uptake by maghemite was investigated on both the macroscopic and the molecular level. Maghemite nanoparticles exhibited fast adsorption kinetics toward selenium(IV). Batch experiments showed a decreased sorption with increasing pH (3.5-11). Ionic strength variations (0.01 to 0.1 M NaCl) had no significant influence on selenium(IV) uptake. Electrophoretic mobility measurements revealed a significant shift toward lower values of the isoelectric point of maghemite upon selenium(IV) uptake, suggesting the formation of inner-sphere surface complexes. At the molecular level, using X-ray Absorption Fine-Structure Spectroscopy (EXAFS), the formation of both bidentate binuclear corner-sharing ((2)C) and bidentate mononuclear edge-sharing ((1)E) inner-sphere surface complexes was observed, with a trend toward solely (1)E complexes at high pH. The absence of a tridentate surface complex as observed for arsenic(III) and antimonite(III) might be due to the relatively small size of the Se(IV)O3 unit. These new spectroscopic results can be implemented in reactive transport models to improve the prediction of selenium migration behavior in the environment as well as its monitoring through its interaction with maghemite or maghemite layers at the surface of magnetite. Due to its chemical stability even at low pH and its magnetization properties allowing magnetic separation, maghemite is a promising sorbing phase for the treatment of Se polluted waters.",
Arsenic,2345808,"Modeling spatial patterns in soil arsenic to estimate natural baseline concentrations Abstract: Arsenic in soil is an important public health concern, but risk-based toxicity regulatory standards derived from laboratory studies should also consider concentrations measured away from obvious contamination (i.e., baseline concentrations that approximate natural background) to avoid unnecessary remediation burdens on society. We used soil and stream sediment samples from the USGS National Geochemical Survey to assess the spatial distribution of As over a 1.16 x 10(5) km(2) area corresponding to the state of Ohio. Samples were collected at 348 soil and 144 stream sites at locations selected to minimize anthropogenic inputs. Total As was measured by sodium peroxide fusion with subsequent dissolution using concentrated HCl and analysis using hydride-generation atomic absorption spectrometry. Arsenic in the soil and streambed samples ranged from 2.0 to 45.6 mg kg(-1). Sequential Gaussian simulation was used to map the expected concentration of As and its uncertainty. Five areas of elevated concentration, greater than the median of 10 mg kg(-1), were identified, and relationships to geologic parent materials, glacial sedimentation, and soil conditions interpreted. Arsenic concentrations <4 mg kg(-1) were rare, >10 mg kg(-1) common, and >20 mg kg(-1) not unusual for the central and west central portions of Ohio. Concentrations typically exceeded the soil As human generic screening level of 0.39 mg kg(-1), a value corresponding to an increase in cancer risk of 1 in 1,000,000 for soil ingestion. Such results call into question the utility of the USEPA and similarly low soil screening levels. The contrast between laboratory screens and concentrations occurring in nature argue for risk assessment on the basis of baseline concentrations.",
Arsenic,674798,Biological monitoring of exposure to metals a report Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN WORKER LEAD CHROMIUM ARSENIC COBALT NICKEL,
Arsenic,1018444,"Toxic effects of arsenic (As3+) and other metal ions on acute promyelocytic leukemia cells Abstract: Since arsenic compounds reportedly induced complete remission in patients with acute promyelocytic leukemia (APL) in China, we studied the in vitro effect of metal ions including As3+, As5+, Cd2+, Ga3+, Ge4+, Hg2+, Se4+, and Zn2+ on myeloid cell lines. One-tenth microM As3+ caused growth suppression and morphological changes resembling differentiation in NB4 cells, but did not induce the maturation-markers, CD11b, CD14 and NBT-reductase. More than 1 microM As3+ caused the time- and dose-dependent apoptosis of NB4 cells. Other metal ions at the same concentrations induced neither morphological changes nor apoptosis in myeloid cell lines including NB4, whereas Cd2+, Ga3+, and Hg2+ induced moderate and non-specific growth suppression. All-trans retinoic acid (ATRA)-resistant NB4 cells were similarly sensitive to As3+. Among the clinical leukemia samples, As3+ was selectively toxic to APL cells regardless of ATRA-sensitivity. These findings suggest that APL cells are sensitive to As3+, and that As3+ acts on APL cells via a different pathway than ATRA.",
Arsenic,732048,"Arsenite maintains germinative state in cultured human epidermal cells Abstract: Arsenic is a well-known carcinogen for human skin, but its mechanism of action and proximal macromolecular targets remain to be elucidated. In the present study, low micromolar concentrations of sodium arsenite maintained the proliferative potential of epidermal keratinocytes, decreasing their exit from the germinative compartment under conditions that promote differentiation of untreated cells. This effect was observed in suspension and in post-confluent surface cultures as measured by colony-forming ability and by proportion of rapidly adhering colony-forming cells. Arsenite-treated cultures exhibited elevated levels of beta1-integrin and beta-catenin, two proteins enriched in cells with high proliferative potential. Levels of phosphorylated (inactive) glycogen synthase kinase 3beta were higher in the treated cultures, likely accounting for the increased levels of transcriptionally available beta-catenin. These findings suggest that arsenic could have co-carcinogenic and tumor co-promoting activities in the epidermis as a result of increasing the population and persistence of germinative cells targeted by tumor initiators and promoters. These findings also identify a critical signal transduction pathway meriting further exploration in pursuit of this phenomenon.",
Arsenic,2149184,"Foci of contamination of Listeria monocytogenes in different cheese processing plants Abstract: Listeria monocytogenes is a ubiquitous bacterium widely distributed in the environment that can cause a severe disease in humans when contaminated foods are ingested. Cheese has been implicated in sporadic cases and in outbreaks of listeriosis worldwide. Environmental contamination, in several occasions by persistent strains, has been considered an important source of finished product contamination. The objectives of this research were to (i) evaluate the presence of L. monocytogenes within the factory environments and cheeses of three processing plants, artisanal producer of raw ewe's milk cheeses (APC), small-scale industrial cheese producer (SSI) and industrial cheese producer (ICP) each producing a distinct style of cheese, all with history of contamination by L. monocytogenes (ii) and identify possible sources of contamination using different typing methods (arsenic and cadmium susceptibility, geno-serotyping, PFGE). The presence of markers specific for 3 epidemic clones (ECI-ECIII) of L. monocytogenes was also investigated. Samples were collected from raw milk (n=179), whey (n=3), cheese brining solution (n=7), cheese brine sludge (n=505), finished product (n=3016), and environment (n=2560) during, at least, a four-year period. Listeria monocytogenes was detected in environmental, raw milk and cheese samples, respectively, at 15.4%, 1.1% and 13.6% in APC; at 8.9%, 2.9% and 3.4% in SSI; and at 0%, 21.1% and 0.2% in ICP. Typing of isolates revealed that raw ewe's milk and the dairy plant environment are important sources of contamination, and that some strains persisted for at least four years in the environment. Although cheeses produced in the three plants investigated were never associated with any case or outbreak of listeriosis, some L. monocytogenes belonging to specific PFGE types that caused disease (including putative epidemic clone strains isolated from final products) were found in this study.",
Arsenic,1070462,"Role of Aspergillus niger acrA in arsenic resistance and its use as the basis for an arsenic biosensor Abstract: Arsenic contamination of groundwater sources is a major issue worldwide, since exposure to high levels of arsenic has been linked to a variety of health problems. Effective methods of detection are thus greatly needed as preventive measures. In an effort to develop a fungal biosensor for arsenic, we first identified seven putative arsenic metabolism and transport genes in Aspergillus niger, a widely used industrial organism that is generally regarded as safe (GRAS). Among the genes tested for RNA expression in response to arsenate, acrA, encoding a putative plasma membrane arsenite efflux pump, displayed an over 200-fold increase in gene expression in response to arsenate. We characterized the function of this A. niger protein in arsenic efflux by gene knockout and confirmed that AcrA was located at the cell membrane using an enhanced green fluorescent protein (eGFP) fusion construct. Based on our observations, we developed a putative biosensor strain containing a construct of the native promoter of acrA fused with egfp. We analyzed the fluorescence of this biosensor strain in the presence of arsenic using confocal microscopy and spectrofluorimetry. The biosensor strain reliably detected both arsenite and arsenate in the range of 1.8 to 180 ?g/liter, which encompasses the threshold concentrations for drinking water set by the World Health Organization (10 and 50 ?g/liter).",
Arsenic,1021321,Arsenic accumulation and acute toxicity in aquacultural juvenile milkfish (Chanos chanos) from blackfoot disease area in Taiwan Abstract: ,
Arsenic,1677557,"Organo-modified sericite in the remediation of an aquatic environment contaminated with As(III) or As(V) Abstract: The aim of this investigation was to obtain the hybrid material precursor to the naturally and abundantly available sericite, a mica-based clay; the materials were further employed in the remediation of arsenic from aqueous solutions. The study was intended to provide a cost-effective and environmentally benign treatment technology. The hybrid organo-modified sericite was obtained using hexadecyltrimethylammonium bromide (HDTMA) and alkyldimethylbenzylammonium chloride (AMBA) organic surfactants by introducing regulated doses of HDTMA or AMBA. The materials were characterized using infrared and X-ray diffraction analytical data, whereas the surface morphology was discussed by taking its SEM images. These materials were employed to assess the pre-concentration and speciation of As(III) and As(V) from aqueous solutions. The batch reactor data showed that increasing the sorptive concentration (from 1.0 to 15.0 mg/L) and pH (i.e., pH 2.0 to 10.0) caused the percent uptake of As(III) and As(V) to decrease significantly. The kinetic data showed that a sharp initial uptake of arsenic reached its equilibrium state within about 50 min of contact time, and the sorption kinetics followed a pseudo-second-order rate law both for As(III) and As(V) sorption. A 1,000 times increase in the background electrolyte concentration, i.e., NaNO3, caused a significant decrease in As(III) removal, whereas As(V) was almost unaffected, which inferred that As(III) was adsorbed, mainly by the van der Waals or even by the electrostatic attraction, whereas As(V) was adsorbed chemically and formed &quot;inner-sphere&quot; complexes at the solid/solution interface. The equilibrium state modeling studies indicated that the sorption data fitted well the Freundlich and Langmuir adsorption isotherms. Henceforth, the removal capacity was calculated under these equilibrium conditions. It was noted that organo-modified sericite possessed a significantly higher removal capacity compared to its virgin sericite. Between these two organo-modified sericite, the HDTMA-modified sericite possessed a higher removal capacity compared to the AMBA-modified sericite.",
Arsenic,1597317,"Time course of urothelial changes in rats and mice orally administered arsenite Abstract: Inorganic arsenic (arsenite and arsenate) at high exposures is a known human carcinogen, inducing tumors of the urinary bladder, skin, and lungs. In two experiments, we examined the urothelial proliferative effects of treatment with 173 ppm sodium arsenite (100 ppm arsenic) in the drinking water for 6 and 24 hr, and 3, 7, and 14 days in female F344 rats and 43.3 ppm sodium arsenite (25 ppm arsenic) in female C57BL/6 wild-type and arsenic (+3 oxidation state) methyltransferase knockout (As3mt KO) mice that are unable to methylate arsenicals. In the rat and both mouse genotypes, scanning electron microscopy showed cytotoxic urothelial changes as early as 6 hr after the start of arsenic exposure. The severity of As(III)-induced cytotoxic urothelial changes increased over time in the rat and in the As3mt KO mouse. Light microscopy showed an increase in urothelial hyperplasia in the rat. No significant increases in bromodeoxyuridine-labeling index were observed. The data support the hypothesis that the sequence of events in the mode of action for urothelial effects of orally administered inorganic arsenic in the rat and mouse involves superficial cytotoxicity with consequent regenerative increased cell proliferation similar to the findings associated with the administration of dimethylarsinic acid (DMA(V)) in rats.",
Arsenic,1936123,Arsenic removal from Pinctada martensii enzymatic hydrolysate by using Zr(IV)-loaded chelating resin Abstract: ,
Arsenic,1343392,"Preliminary analysis of lung cancer incidence in arsenic exposed population Abstract: The subject of our analysis was a database of 844 lung cancer cases collected within 15 years (three 5-year intervals) in a region polluted by emissions from burning of coal with high arsenic content ranging between 900 and 1500 g per metric ton of dry coal. The standardized incidence of lung cancer (each confirmed by biopsy or autopsy histological examination) in a district with population similar to125,000 in non-occupational settings ranged from 67.57 to 88.63 in men and from 7.04 to 10.88 in women per 100,000 (study base 961,960 man/year and 977,940 woman/year) while relevant data for occupational settings (male workers of power-plant burning arsenic-rich coal) ranged from 31.76 to 988.94 per 100,000 (study base 21,360 man/year). Smoking habit was carefully registered in all cancer patients including lung cancer cases and the potential contribution of both factors is subject of a current analysis. Exposure assessment was based on biological monitoring. Determination of arsenic was done in groups of 10-year-old boys (in non-occupational settings) by analyzing hair and urine samples at different localities situated up to distances of 30 km from the local power plant. The results obtained seemed to suggest that arsenic is probably a promotor rather than a true carcinogen, similarly to a previous case of our analysis of arsenic-exposure-related skin basalioma incidence. The non-threshold concept of arsenic carcinogenicity seems not to be supported by the results of our preliminary meta-analysis.",
Arsenic,1508659,"Tunable reporter signal production in feedback-uncoupled arsenic bioreporters Abstract: Escherichia coli-based bioreporters for arsenic detection are typically based on the natural feedback loop that controls ars operon transcription. Feedback loops are known to show a wide range linear response to the detriment of the overall amplification of the incoming signal. While being a favourable feature in controlling arsenic detoxification for the cell, a feedback loop is not necessarily the most optimal for obtaining highest sensitivity and response in a designed cellular reporter for arsenic detection. Here we systematically explore the effects of uncoupling the topology of arsenic sensing circuitry on the developed reporter signal as a function of arsenite concentration input. A model was developed to describe relative ArsR and GFP levels in feedback and uncoupled circuitry, which was used to explore new ArsR-based synthetic circuits. The expression of arsR was then placed under the control of a series of constitutive promoters, which differed in promoter strength, and which could be further modulated by TetR repression. Expression of the reporter gene was maintained under the ArsR-controlled P(ars) promoter. ArsR expression in the systems was measured by using ArsR-mCherry fusion proteins. We find that stronger constitutive ArsR production decreases arsenite-dependent EGFP output from P(ars) and vice versa. This leads to a tunable series of arsenite-dependent EGFP outputs in a variety of systematically characterized circuitries. The higher expression levels and sensitivities of the response curves in the uncoupled circuits may be useful for improving field-test assays using arsenic bioreporters.",
Arsenic,627026,"Arsenite reduces insulin secretion in rat pancreatic beta-cells by decreasing the calcium-dependent calpain-10 proteolysis of SNAP-25 Abstract: An increase in the prevalence of type 2 diabetes has been consistently observed among residents of high arsenic exposure areas. We have previously shown that in rat pancreatic beta-cells, low arsenite doses impair the secretion of insulin without altering its synthesis. To further study the mechanism by which arsenite reduces insulin secretion, we evaluated the effects of arsenite on the calcium-calpain pathway that triggers insulin exocytosis in RINm5F cells. Cell cycle and proliferation analysis were also performed to complement the characterization. Free [Ca2+]i oscillations needed for glucose-stimulated insulin secretion were abated in the presence of subchronic low arsenite doses (0.5-2 microM). The global activity of calpains increased with 2 microM arsenite. However, during the secretion of insulin stimulated with glucose (15.6 mM), 1 microM arsenite decreased the activity of calpain-10, measured as SNAP-25 proteolysis. Both proteins are needed to fuse insulin granules with the membrane to produce insulin exocytosis. Arsenite also induced a slowdown in the beta cell line proliferation in a dose-dependent manner, reflected by a reduction of dividing cells and in their arrest in G2/M. Data obtained showed that one of the mechanisms by which arsenite impairs insulin secretion is by decreasing the oscillations of free [Ca(2+)]i, thus reducing calcium-dependent calpain-10 partial proteolysis of SNAP-25. The effects in cell division and proliferation observed with arsenite exposure can be an indirect consequence of the decrease in insulin secretion.",
Arsenic,1028856,"Risk factors for non-melanomatous skin cancer in Alexandria, Egypt Abstract: The role of constitutional and environmental factors on the risk of non-melanomatous skin cancer was evaluated in a case-control study conducted in 1992 in Alexandria, Egypt, on 136 incident histologically confirmed (99 basal-cell and 37 squamous-cell) cases of non-melanomatous skin cancer (NMSC) and 145 controls in hospital for a broad spectrum of acute non-sun-related dermatological conditions. In relation to skin colour, compared with brown-skinned subjects, the multivariate relative risks (RR) were 2.3 for olive-skinned subjects and 3.8 for fair/medium-skinned subjects. Three cases and 29 controls were black (RR = 0.2). The trend in risk with skin colour was significant. Likewise, compared with subjects with brown or hazel eyes, those with green or blue eyes had a RR of 3.1. In relation to acute sun reaction, compared with subjects reporting easy tanning, the RRs were 2.5 for subjects reporting moderate tanning and 4.7 for those reporting easy burning. The risk of NMSC was higher for subjects reporting an outdoor occupation than for those reporting an indoor occupation (RR = 7.7). A significant trend in risk was observed with degree of sun exposure: compared with subjects reporting light sun exposure, the RR was 3.0 for those reporting moderate exposure, and 6.1 for those reporting heavy sun exposure. There was an indication of a relationship between clothing pattern and skin-cancer risk: compared with subjects reporting frequent use of traditional Egyptian clothes, the RR for dressing in short clothes was 1.8. The presence of signs of photodamage was also associated with NMSC (RR = 3.7). Exposure to arsenic was reported by 10 cases and 1 control (RR = 9.5). A positive interaction between sun exposure and skin colour was observed, and the RR rose to 14.2 for medium- or fair-skinned subjects with heavy exposure compared with brown- or black-skinned subjects with light or moderate sun exposure. In this Egyptian population, over 60% of NMSC could be attributed to sun exposure and approximately 45% to skin colour.",
Arsenic,735050,"Nrf2 protects human bladder urothelial cells from arsenite and monomethylarsonous acid toxicity Abstract: Arsenic is widely spread in our living environment and imposes a big challenge on human health worldwide. Arsenic damages biological systems through multiple mechanisms including the generation of reactive oxygen species. The transcription factor Nrf2 regulates the cellular antioxidant response that protects cells from various insults. In this study, the protective role of Nrf2 in arsenic toxicity was investigated in a human bladder urothelial cell line, UROtsa. Using a UROtsa cell line stably infected with Nrf2-siRNA, we clearly demonstrate that compromised Nrf2 expression sensitized the cells to As(III)- and MMA(III)-induced toxicity. On the other hand, the activation of the Nrf2 pathway by tert-butylhydroquinone (tBHQ) and sulforaphane (SF), the known Nrf2-inducers, rendered UROtsa cells more resistant to As(III) and MMA(III). Furthermore, the wild-type mouse embryo fibroblast (WT-MEF) cells were protected from As(III)- and MMA(III)-induced toxicity following Nrf2 activation by tBHQ or SF, whereas neither tBHQ nor SF conferred protection in the Nrf2(-/-)MEF cells, demonstrating that tBHQ- or SF-mediated protection against As(III)- and MMA(III)-induced toxicity depends on Nrf2 activation. These results, obtained by both loss of function and gain of function analyses, clearly demonstrate the protective role of Nrf2 in arsenic-induced toxicity. The current work lays the groundwork for using Nrf2 activators for therapeutic and dietary interventions against adverse effects of arsenic.",
Arsenic,1519071,"Advection of surface-derived organic carbon fuels microbial reduction in Bangladesh groundwater Abstract: Chronic exposure to arsenic (As) by drinking shallow groundwater causes widespread disease in Bangladesh and neighboring countries. The release of As naturally present in sediment to groundwater has been linked to the reductive dissolution of iron oxides coupled to the microbial respiration of organic carbon (OC). The source of OC driving this microbial reduction-carbon deposited with the sediments or exogenous carbon transported by groundwater-is still debated despite its importance in regulating aquifer redox status and groundwater As levels. Here, we used the radiocarbon ((14)C) signature of microbial DNA isolated from groundwater samples to determine the relative importance of surface and sediment-derived OC. Three DNA samples collected from the shallow, high-As aquifer and one sample from the underlying, low-As aquifer were consistently younger than the total sediment carbon, by as much as several thousand years. This difference and the dominance of heterotrophic microorganisms implies that younger, surface-derived OC is advected within the aquifer, albeit more slowly than groundwater, and represents a critical pool of OC for aquifer microbial communities. The vertical profile shows that downward transport of dissolved OC is occurring on anthropogenic timescales, but bomb (14)C-labeled dissolved OC has not yet accumulated in DNA and is not fueling reduction. These results indicate that advected OC controls aquifer redox status and confirm that As release is a natural process that predates human perturbations to groundwater flow. Anthropogenic perturbations, however, could affect groundwater redox conditions and As levels in the future.",
Arsenic,1378377,"Effects Of Acute, Sub-Lethal Sodium Arsenate Exposure On Migratory Bird Models: Mitochondrial Function, Oxidative Stress And Time Of Flight Abstract: Arsenic is distributed in the environment at a wide range of concentrations. It is primarily transported in the environment by water and these concentrations vary due to both natural and anthropometric factors. Human factors contributing to higher than normal arsenic levels include: arsenical pesticide application; mining, and metal fabrication. Exposure of migratory birds to arsenic occurs as the result of agricultural runoff into surface waters and accumulation in mine waste ponds. The impact of this exposure has not been thoroughly investigated. We tested the impact of acute, sub-lethal exposure to arsenate on mitochondrial function, oxidative stress and time of flight using surrogate migratory bird species. Na-Arsenate toxicity at 0.0, 20.0, and 40.0 mg/kg via gavage were performed on mallard ducks as a surrogate species of migratory birds. Arsenic disrupts normal mitochondrial function, which can result in diminished intracellular ATP levels and also induce oxidative stress. Brain, heart, and liver tissues were excised and analyzed two hours post exposure for mitochondrial respiratory control ratios (RCRs), antioxidant enzyme activities and lipid peroxidation. At 20mg/kg significant decrease (P<0.05) in RCRs were seen in both heart and brain tissues. A dose-dependent increase in superoxide dismutaste (SOD) activity was observed in all tissues, however, notable changes were not observed in catalase, glutathione peroxidase, or glutathione reductase. A dose-dependent increase in lipid peroxidation was also noted in heart and brain tissues with significance (P<0.05) in the brain at 40mg/kg. Significant increase (P<0.05) in sera creatine kinase (CK) indicating biological damage was demonstrated 24 hours following 20mg/kg exposures. Currently, studies with our Homing Pigeon Model are underway to determine if low-level acute exposures to arsenic have an affect on avian time of flight.",
Arsenic,1341250,"Sensitivity of human dental pulp cells to eighteen chemical agents used for endodontic treatments in dentistry Abstract: To determine the adverse effects against human dental pulp tissue, the sensitivity of human dental pulp cells (D824 cells) to 18 chemical agents used for endodontic treatments in dentistry was examined. The cytotoxicity, as determined by a decrease in colony-forming ability of cells treated with the chemical agents, increased as the concentration increased. As a quantitative measure of the cytotoxic effect, LC(50), the concentration which induces a 50% lethality, was extrapolated from the concentration-response curves. The rank of the chemical agents according to their cytotoxic effect (LC(50)) was sodium arsenite &gt; formaldehyde &gt; hydrogen peroxide &gt; zinc oxide &gt; thymol ? iodoform ? eugenol &gt; guaiacol &gt; ethylenediaminetetraacetic acid ? iodine &gt; procaine &gt; lidocaine ? chloramphenicol ? m-cresol &gt; calcium hydroxide ? sodium hypochlorite ? phenol ? p-phenolsulfonic acid. To compare the cytotoxicity and the levels of apoptosis and mRNA expression of five genes related to the function of dental pulp tissue, D824 cells treated with the LC(50) concentrations of chemical agents were assayed by the TUNEL method and quantitative reverse transcription polymerase chain reaction analysis, respectively. The inducibility of apoptotic cells and the level of mRNA expression of the genes varied with the chemical agents, indicating that both effects occurred independent of the rank of cytotoxic effect of the chemical agents. The results not only provide information concerning cytotoxicity of various chemical agents to human dental pulp cells, but also show an insight into the diversity of the pharmacodynamic action of the chemical agents.",
Arsenic,1357259,"Interactions of Rat Blood Cell Sulfhydryls with Arsenate and Arsenite Abstract: Interactions between arsenic (7440382) and erythrocyte sulfhydryls were studied in-vitro. Blood samples collected from the inferior vena cava of male Sprague-Dawley-rats were incubated with 0 to 25 millimolar (mM) sodium-arsenite (7784465) (As3+) or sodium-arsenate (7778430) (As5+) for up to 5 hours (hr). Sample aliquots were withdrawn at hourly intervals to determine changes in the concentrations of nonprotein sulfhydryls (NPSHs), reduced glutathione (GSH), oxidized glutathione (GSSG), and arsenic speciation by standard techniques. Possible arsenic binding proteins were identified in hemolyzed blood samples by arsenic affinity chromatography and sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS). As5+ caused significant dose and time dependent decreases in erythrocyte NPSH concentrations, a 55% decrease being observed 3hr after incubation with 10mM As5+ and an 80% decrease being measured after 5hr incubation with 25mM As5+. As3+ also induced a dose and time dependent NPSH depletion. As3+ was more potent than As5+ at equimolar concentrations of 0.5, 1, 5 and 10mM. As5+ and As3+ induced a dose and time dependent depletion of GSH, the 10mM doses causing 50 to 60% decreases after 5hr. GSSG concentrations were significantly increased by As5+ and As3+, but the increases did not match the decreases in GSH concentration. The increases in GSSG concentration were more pronounced with As3+. As5+ was reduced to As3+ during the incubations. The extent of reduction varied inversely with As5+ concentration, ranging from 16.8% after incubation with 0.04mM As5+ to 4.1% after incubation with 10.0mM As5+ for 5hr. Pretreatment of the blood samples with 20mM N-ethylmaleimide (128530) (NEM), a sulfhydryl depleting agent, inhibited reduction of As5+ to As3+. No GSH could be detected following NEM pretreatment. This indicated that reduction of As5+ to As3+ in erythrocytes depended on the presence of sulfhydryls. Arsenic affinity chromatography and SDS/PAGE indicated that the major arsenic binding protein appeared to be hemoglobin. The authors conclude that in rat erythrocytes As5+ participates in redox reactions with GSH. The products of this are As3+ and some oxidized sulfhydryls. The main protein binding species for arsenic in erythrocytes is hemoglobin.",
Arsenic,1579287,"Derivation of Soil-Screening Thresholds to Protect the Chisel-Toothed Kangaroo Rat from Uranium Mine Waste in Northern Arizona Abstract: Chemical data from soil and weathered waste material samples collected from five uranium mines north of the Grand Canyon (three reclaimed, one mined but not reclaimed, and one never mined) were used in a screening-level risk analysis for the Arizona chisel-toothed kangaroo rat (Dipodomys microps leucotis); risks from radiation exposure were not evaluated. Dietary toxicity reference values were used to estimate soil-screening thresholds presenting risk to kangaroo rats. Sensitivity analyses indicated that body weight critically affected outcomes of exposed-dose calculations; juvenile kangaroo rats were more sensitive to the inorganic constituent toxicities than adult kangaroo rats. Species-specific soil-screening thresholds were derived for arsenic (137 mg/kg), cadmium (16 mg/kg), copper (1,461 mg/kg), lead (1,143 mg/kg), nickel (771 mg/kg), thallium (1.3 mg/kg), uranium (1,513 mg/kg), and zinc (731 mg/kg) using toxicity reference values that incorporate expected chronic field exposures. Inorganic contaminants in soils within and near the mine areas generally posed minimal risk to kangaroo rats. Most exceedances of soil thresholds were for arsenic and thallium and were associated with weathered mine wastes.",
Arsenic,8539,Studies of cytogenetic effects of sodium arsenicals on mammalian cells in vitro Abstract: The cytotoxic and cytogenetic effect of sodium arsenite and sodium arsenate on Chinese hamster ovary (CHO) cells is reported. Chromosome aberrations were induced with both arsenic compounds. Trivalent arsenic was more clastogenic than pentavalent arsenic. Sodium arsenite was also shown to produce increased sister chromatid exchange in CHO cells and increased chromosome breakage in human lymphocytes.,
Arsenic,1032461,"Retrospective observations on the geographical relationship between Rhipicephalus appendiculatus and East Coast fever in southern Africa Abstract: East Coast fever appeared in southern Africa in 1902, after the importation of cattle from East Africa, and spread throughout the range of Rhipicephalus appendiculatus until it reached the southern limit of distribution of this tick in 1916. It was progressively eradicated by quarantine, destocking, slaughter and frequent dipping in arsenic. The last case occurred in Swaziland in 1960. A computer based system for matching climates and ecology (CLIMEX) revealed a direct correlation between the climatic favorability of different areas for the tick and the time required to eradicate the disease.",
Arsenic,1019541,"Theb1?+(b0+) ?X3??(X10+,X21) anda1?(a2) ?X21 Transitions of AsI Abstract: Emission spectra of theb1?+(b0+) ?X3??(X10+,X21) anda1?(a2) ?X21 transitions of AsI have been measured in the near-infrared spectral region with a Fourier-transform spectrometer. The arsenic iodide radicals were generated and excited in a fast-flow system by reaction of arsenic vapor (Asx) with iodine and microwave-discharged oxygen. The most prominent features in the spectrum are six band sequences of the strongb1?+(b0+) ?X3??(X10+) transition in the range 800–900 nm. With much lower intensities the hitherto unknownb1?+(b0+) ?X3??(X21) subsystem and thea1?(a2) ?X21 transition near 1660 nm are observed. Vibrational analyses have yielded improved molecular constants for theX10+andb0+states and first values of the electronic energies and vibrational constants of theX21 anda2 states (in cm?1),X21:Te= 289.8(2), ?e= 255.2(2), ?exe= 0.68(7),a2:Te= 6305.4(3), ?e= 267.8(1), ?exe= 0.56(2), where the numbers in parentheses are the standard deviations of the parameters.",
Arsenic,1070391,"Biomonitoring of heavy metals in fish from the Danube River Abstract: The Croatian part of the Danube River extends over 188 km and comprises 58 % of the country's overall area used for commercial freshwater fishing. To date, the heavy metal contamination of fish in the Croatian part of the Danube has not been studied. The main purpose of this study was to determine heavy metal levels in muscle tissue of sampled fish species and to analyze the measured values according to feeding habits of particular groups. Lead ranged from 0.015 ?g-1 dry weight in planktivorous to 0.039 ?g-1 dry weight in herbivorous fish, cadmium from 0.013 ?g-1 dry weight in herbivorous to 0.018 ?g-1 dry weight in piscivorous fish, mercury from 0.191 ?g-1 dry weight in omnivorous to 0.441 ?g-1 dry weight in planktivorous fish and arsenic from 0.018 ?g-1 dry weight in planktivorous to 0.039 ?g-1 dry weight in omnivorous fish. Among the analyzed metals in muscle tissue of sampled fish, only mercury exceeded the maximal level (0.5 mg kg-1) permitted according to the national and EU regulations determining maximum levels for certain contaminants in foodstuffs, indicating a hazard for consumers of fish from the Danube River.",
Arsenic,1352529,Novel Bioactive Hybrid Composites Based on Coordination Compounds of Some Tertiary Arsines with Mercury(II) Halides Abstract: ,
Arsenic,1794776,"Uptake and accumulation of arsenic in different organs of carrot irrigated with As-rich water Abstract: Irrigation with arsenic (As)-rich water in agricultural soil may increase high levels of As in crops and cause food chain contamination. In this study, a greenhouse experiment was established using Spanish agricultural soil (Valladolid and Segovia provinces), that are extensively cultivated for carrot plant, to investigate the process of As uptake, bioaccumulation, and translocation of As from root to shoot and leaves in carrot plant. Arsenic concentrations in different organs of carrot plant, rhizosphere soil, and soil solutions were determined by hydride generation atomic absorption spectrometry (AAS). High concentrations of As in irrigation water, and the alkaline and sandy character of this soil enhanced As uptake in carrot plants indicating the potential health risk from consumption of carrots cultivated in these areas. Bioaccumulation of As into the leaves and roots increased with increase of As concentration in irrigation water. Both roots and leaves demonstrated a higher accumulation rate of As at an As concentration of 41 than 131?µg?L?1 in the soil solution. The ratios of Asroot/Asleaves showed no statistically significant differences for the different irrigation treatments, and had an average value of 0.36 indicating the high magnitude of As translocation from roots to leaves in carrot plants. The leaves of carrots had a higher affinity for As than roots did. The correlation between As uptake by leaves or roots of carrots and the soluble As in rhizosphere soil did not demonstrate a linear or a plateau curve, indicating a slow but continuous constant As absorption which could be prolonged over time with high potential environmental risks.",
Arsenic,710878,"A biokinetic model to describe the distribution and excretion of arsenic by man following acute and chronic intakes of arsenite/arsenate compounds by ingestion Abstract: An empirical mathematical model, comprising 17 compartments, has been produced to describe the biokinetics of ingested inorganic arsenic (As) in man - required to interpret bioassay data and to predict As tissue concentrations resulting from acute and chronic intakes of inorganic As. The rate constants used to describe the bi-directional transfer of As between compartments were chosen to result in model outcomes that match published data on the distribution of As in tissues and on the retention and excretion of radioisotopes of As administered to human subjects. The model was deployed in acute and chronic intake modes to produce predictions of tissue concentrations and excretion levels. Under conditions of chronic daily intake (1 ?g d(-1)) for 50 years predicted final tissue concentrations vary by a factor of ? 2. Highest concentrations are predicted to occur in skin and bone (? 230 ng kg(-1)). Tissue concentrations in all tissues other than bone are predicted to reach equilibrium after ? 100 days, and at this time, the amount of As excreted in urine has also reached approximate equilibrium at 79% of the daily dietary intake. This level then remains relatively constant unless intake ceases when tissue levels of As fall rapidly. Data on organic and inorganic As concentrations in urine were used to predict inorganic As intake and average tissue content for the USA population. Predicted tissue concentrations ranged from 2.3 ?g kg( -1) in skin to 1.1 ?g kg(-1) in muscle for an average inorganic As intake of 9.3 ?g d(-1).",
Arsenic,470241,"Chemical speciation of fine particle bound trace metals Abstract: This study reported quantifications of fine particle bound trace metals and their potential health risks for residents in Guangzhou, a rapidly developing and most populated city in South China. The fine particle samples were collected from October 29(th). to November 8(th). of 2006 at two different elevations in a mainly residential area and analyzed for the total concentration of aluminum, iron, zinc, lead, manganese, copper, arsenic, chromium, nickel, cadmium, molybdenum and cobalt. Results showed that the fine particle concentrations ranged from 95.8 mu g/m(3) to 194.7 mu g/m(3) at the ground and 83.3-190.0 mu g/m(3) on the roof, which were much higher than the 24 h fine \particle standard (35 mu g/m(3)) recommended by USEPA. The total concentrations of zinc, lead, arsenic, chromium and cadmium in fine particle were 504.8, 201.6, 24.3, 7.7 and 4.4 ng/m(3), respectively, which were comparable to other major cities of China, but much higher than major cities outside of China. A sequential extraction procedure was used to fractionate these fine particle bound metals into four different fractions. Results indicated that most toxic metals were mainly distributed in bioavailable fractions. For instance, about 91% of cadmium, 85% of lead and 74% of arsenic were in bioavailable forms. Risk calculations with a simple exposure assessment model showed that the cancer risks of the bioavailable fractions of arsenic, chromium and cadmium were 3 to 33 times greater than usual goal, indicating serious health risks to the residents in this urban area.",
Arsenic,710803,"Arseniasis prevalence and mortality in a multiethnic, endemic township in Guizhou, China Abstract: Farmers in Southwest Guizhou Autonomous Prefecture, China, represent a unique case of arseniasis, which is related to indoor combustion of high arsenic-containing coal instead of to arsenic-contaminated drinking water. A significant difference in the prevalence of arseniasis was observed in two neighboring ethnic clans in one village. The question arose whether the ethnicity-dependent difference observed in this village was more widely spread throughout the whole township. An epidemiologic investigation was designed to explore arseniasis distribution and mortality among all four ethnic groups in a multiethnic township.<br /><br /> The cohort of arseniasis patients, diagnosed and registered in the overall field survey of 1991 as well as all the asymptomatic residents of the township, were enrolled in the present investigation. Indirect standardization was used for calculating the age-adjusted standardized incidence ratio (SIR) of arseniasis, the standardized mortality ratio (SMR) of various death causes (including some cancers), and their corresponding intervals of 95% confidence in both genders and in each local ethnic group.<br /><br /> The descending rank of arseniasis SIRs among local ethnic groups was found as: Hui>Han>Bouyei>Hmong. The descending rank of SMRs of malignancies was displayed as: Han>Hui>Bouyei>Hmong in males and both genders together as well. Concerning deaths of non-malignant causes the rank was observed as: Hui>Han>Bouyei>Hmong in males. The arseniasis SIR for ethnic Hmong residents (both genders combined) was found to be significantly less profound than the overall level in the township. No death cases in diagnosed ethnic Hmong patients and no cases of death from malignant causes in asymptomatic Hmong residents were recorded. The significant increase of arseniasis prevalence was observed in all males, compared with the overall prevalence of all residents. However, a significantly lower prevalence was seen in all females.<br /><br /> Significant ethnicity-dependent difference in arseniasis prevalence and mortality from all causes was found in a multiethnic rural township where farmers have been exposed to the indoor combustion of high arsenic coal for decades. The ethnic Hmong residents seemed to be the least susceptible to arseniasis among the four local ethnic groups.",
Arsenic,1031041,"Mortality of a cohort of tin miners 1941-86 Abstract: The mortality patterns of United Kingdom tin miners were examined in relation to calendar period and duration of underground work with particular attention to lung cancer and exposure to radon. Subjects were all men who had worked for at least one year between 1941 and 1984 at one of two United Kingdom tin mines and for whom a complete work history could be constructed from mine records. Standardised mortality ratios (SMRs) were calculated using national (England and Wales) rates. The pattern of SMRs in relation to potential explanatory variables was analysed using Poisson regression methods. Mortalities from lung cancer and silicosis (including silicotuberculosis) were significantly raised and showed a significant relation with duration of underground work (mortality from stomach cancer was raised in both underground and surface workers, but not significantly). Excess mortality from silica related disease declined steeply from 35% among workers first exposed before 1920 to 1% among those first exposed after 1950. Thirteen surface workers with known exposure to arsenic had high rates of lung and stomach cancer. The SMR for lung cancer showed a consistent pattern in relation to duration of underground exposure, rising from 83 (observed/expected = 8/9.6) for surface workers (without exposure to arsenic) to 447 (15/3.4) for workers with more than 30 years underground exposure. Examination of the SMR for lung cancer by total underground exposure, age, and time since last exposure gave rise to a model for the expression of risk which depends only on total exposure and time since exposure. The fitted model implies that the effect of exposure to radon in a given year has no effect on risk for 10 years, then rapidly rises to a maximum from which the excess risk then declines, halving every 4.3 years. There were no direct measurements of historic radon levels. A conservative estimate based on measurements taken since 1969 by the National Radiological Protection Board and the Mines and Quarries Inspectorate is that the annual dose to an underground worker was about 10 working level months (WLM). Given this assumption, the risk/exposure slope implied by the present data, and the model fitted to it, was somewhat lower than that given in the fourth Committee on the Biological Effects of Ionisation Radiation (BEIR IV) report (about 40% lower for lifetime exposures). The present data also imply different risks depending on the age at exposure, with relatively higher lifetime risks for exposure at older ages, and relatively lower risks for exposures at younger ages. In conclusion, there was a clear relation between exposure to radon and death from lung cancer. The relative risk of lung cancer due to exposure to radon was not constant in cessation of exposure. The lifetime excess risk of lung cancer implied by these data for 40 years exposure at the current statutory limit of four WLM a year starting at age 20, was about 8% (79 excess deaths per 1000 exposed), assuming average smoking habits among the exposed workers. Control of dust concentrations in the mines has substantially reduced--and may have eliminated--direct mortality from silica related disease.",
Arsenic,1345065,"An efficient removal of arsenic from industrial effluents using electro-coagulation as clean technology option Abstract: This paper is a preliminary communication of a study on removal and recovery of heavy metals from industrial waste waters using electro-coagulation (EC) technique. The larger study envisages use of solar energy for producing the D.C. current, and simple chemical methods of standard methods in chemistry like use of hydrochloric acid, hydrogen sulfide, collection of precipitate, incineration and getting metal oxides in the most economical way of metal recovery. However, this paper reports on the removal of Arsenic (As) from industrial effluent using electro-coagulation (EC) technique. The optimization has been performed to increase the removal efficiency of As by varying initial pH (2-10), time of electrolysis (5-30min) and current density (0.8-4.8 A/dm2). For the first time, we notice that the current density 4.8 A/dm2 has been observed to produce the quickest removal (99.9%) within 10min. The phenomenal COD reduction from 400mg/l to 30mg/l with electrolysis time of 15min is a significant finding, to achieve this type of COD reduction by the existing methods generate huge quantities of sludge. The sludge formed in the reaction vessel also have been Investigated.",
Arsenic,2347691,"Arsenic mobilization in the Brahmaputra plains of Assam: groundwater and sedimentary controls Abstract: Arsenic (As) mobilization to the groundwater of Brahmaputra floodplains was investigated in Titabor, Jorhat District, located in the North Eastern part of India. The groundwater and the aquifer geochemistry were characterized in the study area. The range of As concentration in the groundwater varies from 10 to 440 ?g/l with mean concentration 210 ?g/l. The groundwaters are characterized by high dissolved Fe, Mn, and HCO3 (-) and low concentrations of NO3 (-) and SO4 (2-) indicating the reduced conditions prevailing in the groundwater. In order to understand the actual mobilization processes in the area, six core drilling surrounding the two target tube wells (T1 and T2) with high As concentration (three drill-cores surrounds each tube well closely) was done. The sediment was analyzed its chemical, mineralogical, and elemental compositions. A selective sequential extraction suggested that most of the As in the sediment is bound to Fe oxides fractions (32 to 50 %) and the competition for adsorption site by anions (PO4 (3-)) also accounts to significant fractions of the total arsenic extracted. High variability in the extraction as well as properties of the sediment was observed due to the heterogeneity of the sediment samples with different chemical properties. The SEM and EDX results indicate the presence of Fe, Mn coating along with As for most of the sample, and the presence of As associated minerals were calculated using PHREEQC. The mobilization of As into the groundwater was anticipated to be largely controlled by the reductive dissolution of Fe oxides and partly by the competitive anions viz. PO4 (3-).",
Arsenic,1508650,"Structural and mechanistic characterization of L-histidinol phosphate phosphatase from the polymerase and histidinol phosphatase family of proteins Abstract: L-Histidinol phosphate phosphatase (HPP) catalyzes the hydrolysis of l-histidinol phosphate to l-histidinol and inorganic phosphate, the penultimate step in the biosynthesis of l-histidine. HPP from the polymerase and histidinol phosphatase (PHP) family of proteins possesses a trinuclear active site and a distorted (?/?)(7)-barrel protein fold. This group of enzymes is closely related to the amidohydrolase superfamily of enzymes. The mechanism of phosphomonoester bond hydrolysis by the PHP family of HPP enzymes was addressed. Recombinant HPP from Lactococcus lactis subsp. lactis that was expressed in Escherichia coli contained a mixture of iron and zinc in the active site and had a catalytic efficiency of ?10(3) M(-1) s(-1). Expression of the protein under iron-free conditions resulted in the production of an enzyme with a 2 order of magnitude improvement in catalytic efficiency and a mixture of zinc and manganese in the active site. Solvent isotope and viscosity effects demonstrated that proton transfer steps and product dissociation steps are not rate-limiting. X-ray structures of HPP were determined with sulfate, l-histidinol phosphate, and a complex of l-histidinol and arsenate bound in the active site. These crystal structures and the catalytic properties of variants were used to identify the structural elements required for catalysis and substrate recognition by the HPP family of enzymes within the amidohydrolase superfamily.",
Arsenic,1340038,"In utero arsenic exposure is associated with impaired thymic function in newborns possibly via oxidative stress and apoptosis Abstract: Prenatal arsenic exposure is associated with increased infant morbidity and reduced thymus size, indicating arsenic-related developmental immunotoxicity. We aimed to evaluate effects of prenatal arsenic exposure on thymic function at birth and related mechanisms of action. In a Bangladeshi cohort, arsenic was measured in urine (U-As, gestational week (GW) 8 and 30) and blood (B-As, GW14) in 130 women. Child thymic index was measured by sonography at birth and thymic function by signal-joint T-cell receptor-rearrangement excision circles (sjTRECs) in cord blood mononuclear cells (CBMC). In a subsample (n = 44), sjTRECs content in isolated CD4(+) and CD8(+) T cells, expression of oxidative-stress defense and apoptosis-related genes in CBMC, arsenic concentrations (urine, placenta, and cord blood), and oxidative stress markers in placenta and cord blood were measured. In multivariable-adjusted regression, ln U-As (GW8) was inversely associated with ln sjTRECs in CBMC (B = -0.25; 95% confidence interval [CI] -0.48 to -0.01). Using multivariable-adjusted spline regression, ln U-As (GW30) and ln B-As (GW14) were inversely associated with ln sjTRECs in CBMC (B = -0.53; 95% CI -0.93 to -0.13 and B = -1.27; 95% CI -1.89 to -0.66, respectively) below spline knots at U-As 150 µg/l and B-As 6 µg/kg. Similar inverse associations were observed in separated CD4(+) and CD8(+) T cells. Arsenic was positively associated with 8-hydroxy-2'-deoxyguanosine in cord blood (B = 0.097; 95% CI 0.05 to 0.13), which was inversely associated with sjTRECs in CD4(+) and CD8(+) T cells. In conclusion, prenatal arsenic exposure was associated with reduced thymic function, possibly via induction of oxidative stress and apoptosis, suggesting subsequent immunosuppression in childhood.",
Arsenic,1020639,"Toxicological interactions among arsenic, cadmium, chromium, and lead in human keratinocytes Abstract: To evaluate health effects of chemical mixtures, such as multiple heavy metals in drinking water, we have been developing efficient and accurate hazard identification strategies. Thus, in this study, we determine the cytotoxicity of arsenic, cadmium, chromium, and lead, and characterize interactions among these metals in human epidermal keratinocytes. Three immortal keratinocyte cell lines (RHEK-1, HaCaT, and NM1) and primary keratinocytes (NHEK) were used. A statistical approach applying an additivity response surface methodology was used to test the validity of the additivity concept for a 4-metal mixture. Responses of the 4 keratinocyte strains to the metal mixture were highly dose-dependent. A growth stimulatory effect (hormesis) was observed in RHEK-1, NM1, and NHEK cells with the metal mixture at low concentrations (low ppb range). This hormesis effect was not significant in HaCaT. As the mixture concentration increased, a trend of additivity changed to synergistic cytotoxicity in all 4 cell strains. However, in NHEK, RHEK-1, and HaCaT, at the highest mixture concentrations tested, the responses to the metal mixtures were antagonistic. In NM1, no significant antagonistic interaction among the metals was observed. To explore a mechanistic basis for these differential sensitivities, levels of glutathione and metallothioneins I and II were determined in the keratinocyte cell strains. Initial data are consistent with the suggestion that synergistic cytotoxicity turned to antagonistic effects because at highest mixture exposure concentrations cellular defense mechanisms were enhanced.",
Arsenic,627447,"Arsenic exposure is associated with decreased DNA repair in vitro and in individuals exposed to drinking water arsenic Abstract: The mechanism(s) by which arsenic exposure contributes to human cancer risk is unknown ; however, several indirect cocarcinogenesis mechanisms have been proposed. Many studies support the role of As in altering one or more DNA repair processes. In the present study we used individual-level exposure data and biologic samples to investigate the effects of As exposure on nucleotide excision repair in two study populations, focusing on the excision repair cross-complement 1 (ERCC1) component. We measured drinking water, urinary, or toenail As levels and obtained cryopreserved lymphocytes of a subset of individuals enrolled in epidemiologic studies in New Hampshire (USA) and Sonora (Mexico). Additionally, in corroborative laboratory studies, we examined the effects of As on DNA repair in a cultured human cell model. Arsenic exposure was associated with decreased expression of ERCC1 in isolated lymphocytes at the mRNA and protein levels. In addition, lymphocytes from As-exposed individuals showed higher levels of DNA damage, as measured by a comet assay, both at baseline and after a 2-acetoxyacetylaminofluorene (2-AAAF) challenge. In support of the in vivo data, As exposure decreased ERCC1 mRNA expression and enhanced levels of DNA damage after a 2-AAAF challenge in cell culture. These data provide further evidence to support the ability of As to inhibit the DNA repair machinery, which is likely to enhance the genotoxicity and mutagenicity of other directly genotoxic compounds, as part of a cocarcinogenic mechanism of action.",
Arsenic,2278898,"Simulation of the Effects of Seasonally Varying Pumping on Intraborehole Flow and the Vulnerability of Public-Supply Wells to Contamination Abstract: Public-supply wells with long screens in alluvial aquifers can produce waters of differing quality from different depths. Seasonal changes in quality are linked to seasonal changes in pumping rates that influence the distribution of flow into the well screens under pumping conditions and the magnitude and direction of intraborehole flow within the wells under ambient conditions. Groundwater flow and transport simulations with MODFLOW and MT3DMS were developed to quantify the effects of changes in average seasonal pumping rates on intraborehole flow and water quality at two long-screened, public-supply wells, in Albuquerque, New Mexico and Modesto, California, where widespread pumping has altered groundwater flow patterns. Simulation results indicate that both wells produce water requiring additional treatment to maintain potable quality in winter when groundwater withdrawals are reduced because less water is derived from parts of the aquifer that contain water requiring less treatment. Simulation results indicate that the water quality at both wells could be improved by increasing average winter-pumping rates to induce more lateral flow from parts of the aquifer that contain better quality water. Arsenic-bearing water produced by the Albuquerque well could be reduced from 55% to 45% by doubling average winter-pumping rate, while nitrate- and uranium-bearing water produced by the Modesto well could be reduced from 95% to 65% by nearly tripling the average winter-pumping rate. Higher average winter-pumping rates would also reduce the volume of intraborehole flow within both wells and prevent the exchange of poor quality water between shallow and deep parts of both aquifers.",
Arsenic,628485,"Arsenite induces oxidative DNA adducts and DNA-protein cross-links in mammalian cells Abstract: Arsenic is generally recognized as a nonmutagenic carcinogen because sodium arsenite induces DNA damage only at very high concentrations. In this study we demonstrate that arsenite concentrations above 0.25 microM induce DNA strand breaks in both human leukemia cells and Chinese hamster ovary cells. Therefore, DNA damage may be involved in arsenic-induced carcinogenesis. Formamidopyrimidine-DNA glycosylase and proteinase K greatly increased DNA strand breaks in arsenite-treated cells, providing evidence that a large portion of arsenite-induced DNA strand breaks come from excision of oxidative DNA adducts and DNA-protein cross-links. Because DNA strand breaks appear only temporarily during excision repair, the level of detectable DNA strand breaks will be low at any given time point. For this reason many previous studies have only detected low levels of DNA strand breaks. We also show that catalase, and inhibitors of calcium, nitric oxide synthase, superoxide dismutase, and myeloperoxidase, could modulate arsenite-induced DNA damage. We conclude that arsenite induces DNA adducts through calcium-mediated production of peroxynitrite, hypochlorous acid, and hydroxyl radicals.",
Arsenic,1027687,"Cancers related to exposure to arsenic at a copper smelter Abstract: <strong>OBJECTIVE: </strong>This is an update of an earlier study on the relation between exposure to arsenic in air and deaths from respiratory cancer. The purpose was to verify earlier findings of a supralinear dose response relation and to examine relations with other cancers, particularly those reported in studies on drinking water.<br /><br /><strong>METHODS: </strong>An earlier study of 2802 men who worked at a copper smelter for a year or more during the period 1940-64 and who were followed up for deaths during the period 1941-76 was updated until 1986. Estimates of exposure for the period 1977-1984 were added.<br /><br /><strong>RESULTS AND CONCLUSIONS: </strong>The additional follow up confirms the earlier finding that at low doses the increments in death rates for respiratory cancer for a given increment in dose are greater than at high doses. The additional follow up also shows significant increases in cancer of the large intestine and bone, and SMRs &gt; 150 for cancer of the buccal cavity and pharynx, rectal cancer, and kidney cancer. There was a positive relation between exposure to arsenic in air and kidney and bone cancer, but none for the other cancers, except respiratory.",
Arsenic,2149106,"Oxaliplatin-based combination chemotherapy is still effective for the treatment of recurrent and platinum-resistant epithelial ovarian cancer: results from a single center Abstract: <strong>BACKGROUND: </strong>Combination paclitaxel and carboplatin is currently a first-line regimen for ovarian cancer. However, many patients develop tumor recurrence or drug resistance to this regimen. The study aims to investigate the effectiveness and safety of an oxaliplatin + epirubicin + ifosfamide regimen for the treatment of recurrent and drug-resistant epithelial ovarian cancer.<br /><br /><strong>METHODS: </strong>A retrospective analysis of 73 patients with recurrent and drug-resistant ovarian cancer was performed; 38 cases of them received oxaliplatin + epirubicin + ifosfamide regimens (IAP group), 35 patients received non-oxaliplatinbased chemotherapy regimens (control group). The therapeutic effects and side effects of the oxaliplatin + epirubicin + ifosfamide regimen were analyzed and summarized. Kaplan-Meier survival curves and Cox proportional hazards regression were used to compare progression-free and overall survival between the two groups.<br /><br /><strong>RESULTS: </strong>Of the 38 patients in the IAP group, 14 patients (36.84%) achieved complete remission, 12 (31.58%) achieved partial remission, 2 (5.26%) achieved stable disease and 10 (26.32%) developed progressive disease. The overall effective rate (complete or partial remission) of the IAP regime was 68.42%. While, of the 35 patients in the control group, 12 patients (34.29%) achieved complete remission, 3 (8.57%) achieved partial remission, 5 (14.29%) achieved stable disease and 15 (42.86%) developed progressive disease. The overall effective rate was 42.86%, which was lower than that in the IAP group (P = 0.035, ?(2) = 4.836). Progression-free survival was 9.5 months (0-64 months) in the IAP group vs. 3 months (0-74 months) in the non-oxaliplatin group (P = 0.014 by Kaplan-Meier survival curves; HR = 2.260; 95%CI 1.117-4.573; P = 0.023 by Cox proportional hazards regression). Median overall survival was 46 months (9-124 months) in the IAP group vs. 35 months (9-108 months) in non-oxaliplatin group (P = 0.018 by Kaplan-Meier survival curves; HR = 2.272; 95%CI 1.123-4.598; P = 0.022 by Cox proportional hazards regression). In IAP group, 15.79% (6/38) of the patients suffered grade III-IV bone marrow arrest. The main non-hematological side effects of the IAP regimen included nausea and vomiting (21.05%, 8/38), peripheral neurotoxicity (15.79%, 6/38) and hepatic or renal lesions (2.63%, 1/38). The main side effects of the two chemotherapy regimens showed no statistical difference.<br /><br /><strong>CONCLUSION: </strong>The oxaliplatin-based IAP regimen is potentially effective for salvage chemotherapy in patients with recurrent and drug-resistant ovarian cancer, with a better therapeutic effect and tolerable side effects.",
Arsenic,464425,"Arsenic occurrence in Brazil and human exposure Abstract: Environmental exposure to arsenic (As) in terms of public health is receiving increasing attention worldwide following cases of mass contamination in different parts of the world. However, there is a scarcity of data available on As geochemistry in Brazilian territory, despite the known occurrence of As in some of the more severely polluted areas of Brazil. The purpose of this paper is to discuss existing data on As distribution in Brazil based on recent investigations in three contaminated areas as well as results from the literature. To date, integrated studies on environmental and anthropogenic sources of As contamination have been carried out only in three areas in Brazil: (1) the Southeastern region, known as the Iron Quadrangle, where As was released into the drainage systems, soils and atmosphere as a result of gold mining; (2) the Ribeira Valley, where As occurs in Pb-Zn mine wastes and naturally in As-rich rocks and soils; (3) the Amazon region, including the Santana area, where As is associated with manganese ores mined over the last 50 years. Toxicological studies revealed that the populations were not exposed to elevated levels of As, with the As concentrations in surface water in these areas rarely exceeding 10 mu g/L. Deep weathering of bedrocks along with formation of Fe/Al-enriched soils and sediments function as a chemical barrier that prevents the release of As into the water. In addition, the tropical climate results in high rates of precipitation in the northern and southeastern regions and, hence, the As contents of drinking water is diluted. Severe cases of human As exposure related to non-point pollution sources have not been reported in Brazil. However, increasing awareness of the adverse health effects of As will eventually lead to a more complete picture of the distribution of As in Brazil.",
Arsenic,1579358,"Removing of As (V) from aqueous solution using natural and pretreated glauconite and halloysite Abstract: Adsorption of arsenic on clay surfaces is important for the natural and simulated removal of arsenic species from aqueous environments. In this investigation, two samples of clay minerals (glauconite and halloysite) in both untreated and acid activated treated forms were used for the sorption of arsenate from aqueous solution. Glauconite is mainly composed of illite/ smectite mixed layer, kaolinite and quartz. Halloysite is composed of halloysite, kaolinite, quartz, marcasite and trace amount of pyrite. Iron is existed as separated minerals (marcasite and pyrite) in the case of halloysite or present in the structure of glauconite, which play an important role in the adsorption of arsenic. Acid activation followed by calcination enhanced the adsorption capacity compared to the untreated clay minerals due to the increased surface area and pore volume. However, the increasing of acid activation leads to dissolution of iron from sorbent clay materials which in turn lead to decrease the adsorption capacity of As (V). The effects of initial As (V) concentration, contact time and pH on the adsorption of arsenic (V) by the untreated and treated glauconite and halloysite were investigated. Maximum adsorption capacity (about 93%) was recorded for treated halloysite at equilibrium conditions pH5, 240 minute contact time, arsenate concentration 0.90 mg/L, and at temperature 25oC. The adsorption kinetics of glauconite follow the Langmuir pseudo first-order model, while theadsorption kinetic of halloysite was neither fit with pseudo first-order kinetics model nor with pseudosecond-order kinetics model, suggesting adsorption kinetics of halloysite should be further analysis.",
Arsenic,460246,"Mitogen-activated protein kinases mediate arsenic-induced down-regulation of survivin in human lung adenocarcinoma cells Abstract: Survivin is a member of the inhibitors of apoptosis protein (IAP) family and is highly expressed in various cancer cells. However, the molecular mechanisms regulating survivin expression remain unclear. In this study, we investigated the role of mitogen-activated protein kinases (MAPKs) in regulating survivin in the human lung adenocarcinoma cell line H1355 in response to arsenic trioxide (As(3+)). Our data indicated that As(3+) induced cytotoxicity accompanied by down-regulation of survivin, cleavage of Poly ADP-ribosyl polymerase (PARP) and activations of MAPKs, including ERK1/2, p38 and c-jun N-terminal kinase (JNK). We found that blockage of p38 or JNK activation attenuated the As(3+)-induced survivin down-regulation and PARP cleavage with significant reversal of cell viability, however, by only 5-8%. On the other hand, the MEK inhibitor PD098059 or the ubiquitin-proteasome inhibitor MG-132 exhibited little effect on survivin down-regulation and PARP cleavage induced by As(3+). In this study, we demonstrated that As(3+) could down-regulate survivin via activations of p38 and JNK in an ubiquitin-proteasome independent pathway and lead to cytotoxicity and apoptosis in the human lung adenocarcinoma cell line H1355.",
Arsenic,1031045,"Structurally based, selective interaction of arsenite with steroid receptors Abstract: Steroid binding to cognate receptors is of high affinity. However, due to the appreciable homologies in the steroid-binding domains of receptors, this binding is hardly ever totally specific. We have recently obtained evidence that a vicinal dithiol group is involved in steroid binding to glucocorticoid receptors and that these vicinal dithiols are two of the three cysteines in the 16-kDa steroid-binding core. We now report that a comparison of the placement of cysteines in the comparable region of other receptors revealed a lack of similarly closely spaced thiols, which led to the prediction that arsenite would be totally selective in its interaction with glucocorticoid receptors. In fact, 100 microM arsenite inhibited all steroid binding to glucocorticoid receptors while having no effect on the binding of androgen, estrogen, mineralocorticoid, or progesterone receptors. Such total selectivity is not seen for selenite, which is another very potent inhibitor of glucocorticoid binding. This is the first report of absolute selectivity among steroid receptors that is based upon a known structural feature of the receptor protein. This selectivity of arsenite provides the easiest method to date for distinguishing between glucocorticoid and mineralocorticoid receptors and for selectively blocking steroid binding to glucocorticoid receptors in the assays of other receptors.",
Arsenic,1597396,"Responses of Noccaea caerulescens and Lupinus albus in trace elements-contaminated soils Abstract: Plants exposed to trace elements can suffer from oxidative stress, which is characterised by the accumulation of reactive oxygen species, alteration in the cellular antioxidant defense system and ultimately lipid peroxidation. We assessed the most-appropriate stress indexes to describe the response of two plant species, with different strategies for coping with trace elements (TEs), to particular contaminants. Noccaea caerulescens, a hyperaccumulator, and Lupinus albus, an excluder, were grown in three soils of differing pH: an acidic soil, a neutral soil (both contaminated mainly by Cu, Zn and As) and a control soil. Then, plant stress indicators were measured. As expected, N. caerulescens accumulated higher levels of Zn and Cd in shoots than L. albus, this effect being stronger in the acid soil, reflecting greater TE solubility in this soil. However, the shoot concentrations of Mn were higher in L. albus than in N. caerulescens, while the As concentration was similar in the two species. In L. albus, the phenolic content and lipid peroxidation were related with the Cu concentration, whereas the Zn and Cd concentrations in N. caerulescens were more closely related to glutathione content and lipid peroxidation. Interestingly, phytochelatins were only found in L. albus grown in polluted soils. Hence, the two species differed with respect to the TEs which provoked stress and the biochemical indicators of the stress, there being a close relationship between the accumulation of TEs and their associated stress indicators in the different plant organs.",
Arsenic,1346076,A Toxicochemical Review of Gallium Arsenide Abstract: ,
Arsenic,1329637,"Arsenite modulates cardiac substrate preference by translocation of GLUT4, but not CD36, independent of mitogen-activated protein kinase signaling Abstract: The protein thiol-modifying agent arsenite, a potent activator of stress signaling, was used to examine the involvement of MAPKs in the regulation of cardiac substrate uptake. Arsenite strongly induced p38 MAPK phosphorylation in isolated rat cardiac myocytes but also moderately enhanced phosphorylation of p42/44 ERK and p70 S6K. At the level of cardiomyocytic substrate use, arsenite enhanced glucose uptake dose dependently up to 5.1-fold but failed to stimulate long-chain fatty acid uptake. At the substrate transporter level, arsenite stimulated the translocation of GLUT4 to the sarcolemma but failed to recruit CD36 or FABPpm. Because arsenite did not influence the intrinsic activity of glucose transporters, GLUT4 translocation is entirely responsible for the selective increase in glucose uptake by arsenite. Moreover, the nonadditivity of arsenite-induced glucose uptake and insulin-induced glucose uptake indicates that arsenite recruits GLUT4 from insulin-responsive intracellular stores. Inhibitor studies with SB203580/SB202190, PD98059, and rapamycin indicate that activation of p38 MAPK, p42/44 ERK, and p70 S6K, respectively, are not involved in arsenite-induced glucose uptake. In addition, all these kinases do not play a role in regulation of cardiac glucose and long-chain fatty acid uptake by insulin. Hence, arsenite's selective stimulation of glucose uptake appears unrelated to its signaling actions, suggesting that arsenite acts via thiol modification of a putative intracellular protein target of arsenite within insulin-responsive GLUT4-containing stores. Because of arsenite's selective stimulation of cardiac glucose uptake, identification of this putative target of arsenite within the GLUT4-storage compartment may indicate whether it is a target for future strategies in prevention of diabetic cardiomyopathy.",
Arsenic,734863,"Acute toxicity and bioaccumulation of arsenic in freshwater clam Corbicula fluminea Abstract: Arsenic is a potent human carcinogen of skin, lung, and urinary bladder. Freshwater clam Corbicula fluminea is a commercially important native species in Taiwan. C. fluminea is also a suitable biomonitoring test organism. Little is known, however, about the actual effects of arsenic on C. fluminea. The objectives of this study were to provide information on the acute toxicity and bioaccumulation kinetics of arsenic in C. fluminea. We carried out a 14-day exposure experiment to obtain bioaccumulation parameters. Uptake was very rapid when C. fluminea was first exposed and then slightly decayed during the uptake phase of the experiment and an uptake rate constant of 1.718 +/- 6.70 (mean +/- SE) mL g(-1) d(-1) was estimated. The elimination of arsenic from C. fluminea obeyed first-order depuration kinetics (r(2) = 0.85, p &lt; 0.05) with a calculated half-life of 6.80 days. The derived bioaccumulation factor of 16.84 suggests that arsenic has a high potential for bioaccumulation in C. fluminea. This had important implications for dietary exposure of arsenic to humans who eat contaminated clams, because the soft tissue usually constitutes the majority of tissue consumed. The 96-h LC50 value was estimated to be 20.74 (95% CI: 11.74-30.79) mg L(-1) obtained from a 7-day acute toxicity bioassay. We also kinetically linked an acute toxicity model and a Hill sigmoid model to reconstruct an internal effect concentration based dose-response profile to assess the effect of soft tissue arsenic burden on the C. fluminea mortality. This result could be used to support the establishment of an ecological risk assessment to prevent possible ecosystem and human health consequences.",
Arsenic,2149121,"Arsenite binding-induced zinc loss from PARP-1 is equivalent to zinc deficiency in reducing PARP-1 activity, leading to inhibition of DNA repair Abstract: Inhibition of DNA repair is a recognized mechanism for arsenic enhancement of ultraviolet radiation-induced DNA damage and carcinogenesis. Poly(ADP-ribose) polymerase-1 (PARP-1), a zinc finger DNA repair protein, has been identified as a sensitive molecular target for arsenic. The zinc finger domains of PARP-1 protein function as a critical structure in DNA recognition and binding. Since cellular poly(ADP-ribosyl)ation capacity has been positively correlated with zinc status in cells, we hypothesize that arsenite binding-induced zinc loss from PARP-1 is equivalent to zinc deficiency in reducing PARP-1 activity, leading to inhibition of DNA repair. To test this hypothesis, we compared the effects of arsenite exposure with zinc deficiency, created by using the membrane-permeable zinc chelator TPEN, on 8-OHdG formation, PARP-1 activity and zinc binding to PARP-1 in HaCat cells. Our results show that arsenite exposure and zinc deficiency had similar effects on PARP-1 protein, whereas supplemental zinc reversed these effects. To investigate the molecular mechanism of zinc loss induced by arsenite, ICP-AES, near UV spectroscopy, fluorescence, and circular dichroism spectroscopy were utilized to examine arsenite binding and occupation of a peptide representing the first zinc finger of PARP-1. We found that arsenite binding as well as zinc loss altered the conformation of zinc finger structure which functionally leads to PARP-1 inhibition. These findings suggest that arsenite binding to PARP-1 protein created similar adverse biological effects as zinc deficiency, which establishes the molecular mechanism for zinc supplementation as a potentially effective treatment to reverse the detrimental outcomes of arsenic exposure.",
Arsenic,1019258,"Normal values for arsenic and selenium concentrations in human lung tissue Abstract: Normal values and ranges were determined for arsenic and selenium concentrations in lung and hilus tissue. The study group consisted of 50 deceased persons, who were examined by autopsy at the Institute for Pathology of the University of Erlangen-Nuremberg. Taking into consideration topographic-anatomical criteria, samples were taken of each lung lobe and the hilar lymph nodes. The dried tissue was analyzed using by means of hydride atomic absorption spectrometry after wet-oxidative digestion. Normal values ranged for the arsenic concentrations from &lt;1-74 ng/g dry weight and for the selenium concentrations from &lt;3-574 ng/g dry weight. Arsenic was found to accumulate in the hilus tissue, whereas selenium did not. Considerable intraindividual and interindividual variation was found for both arsenic and selenium. There were no statistically significant differences regarding age, smoking habits, and lung diseases. Lung tissue samples from three deceased persons from Houston, Texas, contained lower arsenic concentrations and somewhat higher levels of selenium compared to the German autopsies; these levels were, however, still within the indicated normal ranges. The following conclusions can be drawn from the results available at present: Intraindividual and interindividual variation is high for the arsenic and selenium concentrations in human lung tissue, so that only relatively wide normal ranges can be given for the general population. Smoking habits, age, and lung diseases do not seem to affect the indicated normal ranges. Postmortem determination of arsenic and selenium concentrations in human lung tissue can provide important information on former occupational or environmental exposure.",
Arsenic,628841,"Evidence for induction of oxidative stress caused by chronic exposure of Chinese residents to arsenic contained in drinking water Abstract: Exposure of experimental animals or cultured cells to arsenic induces oxidative stress, but, to date, no examination of this phenomenon in humans has been reported. In this study we conducted a cross-sectional study in Wuyuan, Inner Mongolia, China, to explore the relationship between chronic arsenic exposure from drinking water and oxidative stress in humans. Thirty-three inhabitants who had been drinking tube-well water with high concentrations of inorganic arsenic (mean value = 0.41 mg/L) for about 18 years constituted the high-exposure group, and 10 residents who lived nearby but were exposed to much lower concentrations of arsenic in their drinking water (mean value = 0.02 mg/L) were selected as the low-exposure comparison group. Results of the present study indicated that although the activity for superoxide dismutase (SOD) in blood did not differ significantly between the two groups, the mean serum level of lipid peroxides (LPO) was significantly higher among the high-exposed compared with the low-exposed group. Elevated serum LPO concentrations were correlated with blood levels of inorganic arsenic and its methylated metabolites. In addition, they showed an inverse correlation with nonprotein sulfhydryl (NPSH) levels in whole blood. The subjects in the high-arsenic-exposure group had mean blood NPSH levels 57.6% lower than those in the low-exposure group. Blood NPSH levels were inversely correlated with the concentrations of inorganic arsenic and its methylated metabolites in blood and with the ratio of monomethylarsenic to inorganic arsenic. These results provide evidence that chronic exposure to arsenic from drinking water in humans results in induction of oxidative stress, as indicated by the reduction in NPSH and the increase in LPO. Some possible mechanisms for the arsenic-induced oxidative stress are discussed.",
Arsenic,1030836,"Combining occurrence and toxicity information to identify priorities for drinking-water mixture research Abstract: Characterizing all possible chemical mixtures in drinking water is a potentially overwhelming project, and the task of assessing each mixture's net toxicity even more daunting. We propose that analyzing occurrence information on mixtures in drinking water may help to narrow the priorities and inform the approaches taken by researchers in mixture toxicology. To illustrate the utility of environmental data for refining the mixtures problem, we use a recent compilation of national ground-water-quality data to examine proposed U.S. Environmental Protection Agency (EPA) and Agency for Toxic Substances and Disease Registry (ATSDR) models of noncancer mixture toxicity. We use data on the occurrence of binary and ternary mixtures of arsenic, cadmium, and manganese to parameterize an additive model and compute hazard index scores for each drinking-water source in the data set. We also use partially parameterized interaction models to perform a bounding analysis estimating the interaction potential of several binary and ternary mixtures for which the toxicological literature is limited. From these results, we estimate a relative value of additional toxicological information for each mixture. For example, we find that according to the U.S. EPA's interaction model, the levels of arsenic and cadmium found in U.S. drinking water are unlikely to have synergistic cardiovascular effects, but the same mixture's potential for synergistic neurological effects merits further study. Similar analysis could in future be used to prioritize toxicological studies based on their potential to reduce scientific and regulatory uncertainty. Environmental data may also provide a means to explore the implications of alternative risk models for the toxicity and interaction of complex mixtures.",
Arsenic,1251627,"Selective induction of heme oxygenase-1 isozyme in rat testis by human chorionic gonadotropin Abstract: A radioimmunoassay was developed to assess the response of testicular HO-1 to agents known to increase the microsomal heme oxygenase activity. Treatment of rats with human chorionic gonadotropin (hCG) increased the microsomal heme oxygenase activity in rat testis. The following data suggest that the increase was specific to the HO-1 isozyme: (a) The elution profile of heme oxygenase activity from a DEAE-Sephacel column showed an increase in the HO-1 peak, but not in the HO-2 peak, (b) the Western immunoblot of the testis microsomes showed an increase in HO-1 protein, and (c) the amount of HO-1 protein that was present in the microsomes, when measured by radioimmunoassay, was doubled. Using radioimmunoassay, it was shown that other agents known to increase the testicular heme oxygenase, sodium arsenate and sodium arsenite, also increased the microsomal content of HO-1. An inhibitor of the testicular microsomal heme oxygenase activity, cadmium, also increased the microsomal HO-1 protein. The findings suggest that inducibility of HO-1 extends to tissues other than the liver, in this instance, the testis, and further support the possibility that HO-1 is the only inducible form of heme oxygenase.",
Arsenic,1034015,"Arsenic distribution and neurochemical effects in peroral sodium arsenite exposure of rats Abstract: Early effects of arsenic (7440382) on neural protein and energy metabolism were investigated in rats. Male Wistar-rats received drinking water containing a 0.77 milliMolar solution of sodium-arsenite (7784465) for 4 or 11 days. Left cerebral hemisphere, liver, kidneys, blood samples, and duodenum were analyzed for arsenic. Neural enzyme activity was determined. Results were compared to exposed controls. Arsenic concentrations of controls in nanomoles per gram were: 67 in blood; 1.5 in duodenum; 3.9 in liver; 2.4 in kidney; 0.9 in brain. Values in rats receiving arsenic for 4 days were: 1880 in blood; 44 in duodenum; 61 in liver; 53 in kidney; and 24 in brain. Values in rats drinking arsenic for 11 days were: 3383 in blood; 58 in duodenum; 116 in liver; 161 in kidney; and 63 in brain. Virtually no neurochemical effects were seen at 4 days while axonal acetylcholine esterase and succinate-dehydrogenase activities decreased below control values at 11 days. These enzyme activities remained comparable to control values in neurons. Glial cell acid proteinase was above control values at 11 days; succinate-dehydrogenase, creatine kinase, and 2',3'-cyclic-nucleotide-3'-phosphohydrolase were not affected. The authors conclude that nervous system effects may reflect an early intoxication stage of arsenic poisoning. Impaired adenosine-triphosphate metabolism could account for the biochemical effects in the spinal cord axons.",
Arsenic,1579343,"From Hazardous Waste to Valuable Raw Material: Hydrolysis of CCA-treated Wood for the Production of Chemicals Abstract: Solid wood, metal finnish: Instead of burning waste wood treated with chromated copper arsenite (CCA) or disposing of it in landfills, the CCA-treated wood can be used as a raw material for the production of chemicals. Catalytic or alkaline oxidation together with very mild sulfuric acid extraction produces an easily enzymatically hydrolyzable material. Usage as a raw material for the chemical industry in this manner demonstrates a sustainable and value-added waste management process.",
Arsenic,737297,"Sensitivity of wild cotton rats (Sigmodon hispidus) to the immunotoxic effects of low-level arsenic exposure Abstract: Arsenic is a ubiquitous contaminant of many toxic waste sites around the country and experimental animal trials have indicated that arsenic may be immunotoxic to laboratory rodents. Because wild rodents such as the herbivorous cotton rat (Sigmodon hispidus) reside on many of these toxic waste sites, we explored the sensitivity of their immune systems to oral exposures of environmentally relevant concentrations of inorganic arsenic. We exposed adult male cotton rats (n = 36) to either 0 (controls), 5 (low dose), or 10 (high dose) ppm sodium arsenite in drinking water for 6 weeks. Daily food intake decreased in a dose-dependent manner, ranging from an average of 10.03 +/- 0.45 in the high-dose group to 11.27 +/- 0.42 (SE) g/animal/day in the control group. Mass of testes in the low-dose group increased significantly compared to controls, but there was no difference between the high-dose and control groups. Masses of liver, kidney, adrenals, popliteal lymph nodes, spleen, epididymides, and seminal vesicles and selected hematological parameters were unaffected by arsenic exposure. In vivo cell-mediated immunity, as measured by a phytohemagglutinin-hypersensitivity response to an intradermal challenge, was suppressed 30% in the low-dose group compared to controls; however, responses of those receiving a high dose of arsenic were similar to controls. Arsenic treatment did not have a measurable impact on lymphoproliferative responses of cultured splenocytes to the mitogens Concanavalin A and Pokeweed mitogen, or to the lymphokine interleukin-2. We also observed no impact of low-level arsenic exposure on macrophage phagocytic activity and tumoricidal activity of lymphokine-activated killer cells in vitro. It is possible that malnutrition caused by decreased food intake may eventually lead to atrophy of lymphoid organs and render animals more susceptible to environmental pathogens. However, direct effects of low-level arsenic exposure on immune function of cotton rats was minimal (a moderate depression in the in vivo cell-mediated immunity assay) and may not be clinically relevant with regard to susceptibility to disease in the wild.",1
Arsenic,86172,"Ambient air pollution exposure and cancer Abstract: BIOSIS COPYRIGHT: BIOL ABS. Epidemiologic evidence on the relation between ambient air pollution exposure and cancer is reviewed. The well-documented urban/rural difference in lung cancer incidence and the detection of known carcinogens in the atmosphere gave rise to the hypothesis that long-term exposure to air pollution may have an effect on lung cancer risk. However, problems inherent in assessing adequately the exposure of interest led to considerable difficulties in evaluating this effect. Routinely measured air pollutants do not include, as a rule, established carcinogens, and air pollution measurements usually come from fixed-site monitors, making it difficult to estimate individual exposures, especially long-term. The nature of the exposure and associated measurement problems made ecologic comparisons a natural way to approach the study of air pollution effects on lung cancer risk. The descriptive/ecologic studies which have been undertaken after 1950 often had problems with inadequate con",
Arsenic,1337782,"Development of an Analytical Method for the Determination of Arsenic in Urine by Gas Chromatography-mass spectrometry for Biological Monitoring of Exposure to Inorganic Arsenic Abstract: Objectives: The purpose of this study was to develop an analytical method for the simultaneous determination of inorganic arsenic [As (III) and As (V)] and monomethylarsonic acid (MMA) in urine by gas chromatography-mass spectrometry (GC-MS) for the biological monitoring of exposure to inorganic arsenic. Methods: Arsenic compounds (after reduction of arsenic to the trivalent state) were derivatized with 2,3-dimercapto-1-propanol and then analyzed using a GC-MS. The proposed method was validated according to the US Food and Drug Administration guidelines. The accuracy of the proposed method was confirmed by analyzing Standard Reference Material (SRM) 2669 (National Institute of Standards and Technology). Results: Calibration curves showed linearity in the range 1-100 µg/l for each of the arsenic species, with correlation coefficients of &gt;0.999. For each of the arsenic species, the limits of detection and quantification were 0.2 µg/l and 1 µg/l, respectively. The recoveries were 96-100%, 99-102% and 99-112% for As(III), As(V) and MMA, respectively. Intraday accuracy and precision were 82.7-99.8% and 0.9-7.4%, respectively. Interday accuracy and precision were 81.3-100.0% and 0.8-9.9%, respectively. The analytical values of SRM 2669 obtained by the proposed method were sufficiently accurate. Conclusions: The proposed method overcame the disadvantages of high-performance liquid chromatography with inductively coupled plasma mass spectrometry. It was a robust, selective and cost-effective method suitable for routine analyses and could be useful for the biological monitoring of occupational exposure to inorganic arsenic.",
Arsenic,1936112,"Impact of arsenic toxicity on black gram and its amelioration using phosphate Abstract: The toxicity of arsenic in soil and ground water is one of the most important environmental problems particularly in South-East Asia. Arsenic-polluted irrigation water creates hazard in soil environment and also in crop quality. In the present study, response of black gram (Vigna mungo L.) to arsenic with or without phosphate application was investigated. Arsenic-treated plants showed reduction in their growth and pigment content. Arsenic significantly enhanced lipid peroxidation, electrolyte leakage, and level of proline showing oxidative stress. Arsenic toxicity was associated with an increase in the activities of antioxidative enzymes like superoxide dismutase, peroxidase, and ascorbate peroxidase whereas catalase activity decreased at higher arsenic dose. Joint application of phosphate with arsenic resulted in significant alterations in most of the parameters tested under the purview of arsenic treatment alone which lead to better growth in black gram.",
Arsenic,1240226,"Arsenic and associated trace-elements in groundwater from the Chaco-Pampean plain, Argentina: Results from 100years of research Abstract: The Chaco-Pampean plain, Argentina, is a vast geographical unit (1,000,000km(2)) affected by high arsenic (As) concentrations in universal oxidizing groundwater. The socio-economic development of the region is restricted by water availability and its low quality caused by high salinity and hardness. In addition, high As and associated trace-elements (F, U, V, B, Se, Sb, Mo) concentrations of geogenic origin turn waters unsuitable for human consumption. Shallow groundwater with high As and F concentrations (ranges: &lt;10-5300?g As/L; 51-7,340?gF/L) exceeding the WHO guideline values (As: 10?g/L; F: 1,500?g/L) introduces a potential risk of hydroarsenicism disease in the entire region and fluorosis in some areas. The rural population is affected (2-8 million inhabitants). Calcareous loess-type sediments and/or intercalated volcanic ash layers in pedosedimentary sequences hosting the aquifers are the sources of contaminant trace-elements. Large intra and interbasin variabilities of trace-element concentrations, especially between shallow and deep aquifers have been observed. All areas of the Chaco-Pampean plain were affected in different grades: the Chaco-Salteña plain (in the NNE of the region) and the northern La Pampa plain (in the center-south) have been shown the highest concentrations. The ranges of As and F contents in loess-sediments are 6-25 and 534-3340mg/kg, respectively in the Salí River basin. Three key processes render high As concentrations in shallow aquifers: i) volcanic glass dissolution and/or hydrolysis and leaching of silicates minerals hosted in loess; ii) desorption processes from the surface of Al-, Fe- and Mn-oxi-hydroxides (coating lithic fragments) at high pH and mobilization as complex oxyanions (As and trace elements)in Na-bicarbonate type groundwaters; and iii) evaporative concentration in areas with semiarid and arid climates. Local factors play also an important role in the control of high As concentrations, highly influenced by lithology-mineralogy, soils-geomorphology, actual climate and paleoclimates, hydraulic parameters, and residence time of groundwaters.",
Arsenic,1377973,"Arsenite Maintains Germinative State Of Epidermal Cells By Altering Wnt Signaling Abstract: Arsenic is a common drinking water contaminant and a worldwide health problem. Skin cancer is frequently observed in individuals exposed chronically to arsenic by this route. However, the mechanism of arsenic induced skin cancer is still unknown. We have previously demonstrated that arsenite preserves the population of keratinocytes with the highest proliferative potential, slowing their exit from the germinative pool into the differentiation pathway. The focus of current research is to understand how arsenite upsets this crucial balance. Specifically, the hypothesis tested was stabilized nuclear beta-catenin protein levels are responsible for the preserved proliferative potential of keratinocytes that occurs with arsenite treatment. To this end, cultured human epidermal keratinocytes were retrovirally infected with either a dominant negative beta-catenin previously demonstrated to reduce proliferative potential or a vector control. Cells were treated at confluence with 2 uM arsenite for 3 days. Proliferative capacity was then measured as the fraction of rapidly versus slowly adhering cells that yielded colonies. Arsenite treated cultures infected with the vector alone (control) had more rapidly adhering cells compared to untreated cultures, indicative of a higher proliferative potential. In contrast, cells infected with a dominant negative beta-catenin, which prevents its nuclear stabilization, reversed the fraction of rapidly adhering cells to that of untreated cultures. Second, addition of a soluble Wnt/beta-catenin antagonist, dickkopf 1 (DKK), prevented arsenite from maintaining the level of rapidly adhering cells. Based on these results, -catenin appears to be central in the response of cultured keratinocytes to arsenite treatment, as preventing stabilization of beta-catenin reverses the elevated germinative capacity of arsenite treated keratinocytes. Further, arsenite appears to disrupt signaling upstream of the Wnt cascade, since DKK, an inhibitor of the Wnt co-receptor LRP, yields the same results as direct inhibition of beta-catenin.",
Arsenic,1025147,"Sensitivity to sodium arsenite in human melanoma cells depends upon susceptibility to arsenite-induced mitotic arrest Abstract: Arsenic induces clinical remission in patients with acute promyelocytic leukemia and has potential for treatment of other cancers. The current study examines factors influencing sensitivity to arsenic using human malignant melanoma cell lines. A375 and SK-Mel-2 cells were sensitive to clinically achievable concentrations of arsenite, whereas SK-Mel-3 and SK-Mel-28 cells required supratherapeutic levels for toxicity. Inhibition of glutathione synthesis, glutathione S-transferase (GST) activity, and multidrug resistance protein (MRP) transporter function attenuated arsenite resistance, consistent with studies suggesting that arsenite is extruded from the cell as a glutathione conjugate by MRP-1. However, MRP-1 was not overexpressed in resistant lines and GST-pi was only slightly elevated. ICP-MS analysis indicated that arsenite-resistant SK-Mel-28 cells did not accumulate less arsenic than arsenite-sensitive A375 cells, suggesting that resistance was not attributable to reduced arsenic accumulation but rather to intrinsic properties of resistant cell lines. The mode of arsenite-induced cell death was apoptosis. Arsenite-induced apoptosis is associated with cell cycle alterations. Cell cycle analysis revealed arsenite-sensitive cells arrested in mitosis whereas arsenite-resistant cells did not, suggesting that induction of mitotic arrest occurs at lower intracellular arsenic concentrations. Higher intracellular arsenic levels induced cell cycle arrest in the S-phase and G(2)-phase in SK-Mel-3 and SK-Mel-28 cells, respectively. The lack of arsenite-induced mitotic arrest in resistant cell lines was associated with a weakened spindle checkpoint resulting from reduced expression of spindle checkpoint protein BUBR1. These data suggest that arsenite has potential for treatment of solid tumors but a functional spindle checkpoint is a prerequisite for a positive response to its clinical application.",
Arsenic,1349735,"The p38/reactivating kinase mitogen-activated protein kinase cascade mediates the activation of the transcription factor insulin upstream factor 1 and insulin gene transcription by high glucose in pancreatic beta-cells Abstract: Insulin upstream factor 1 (IUF1), a transcription factor present in pancreatic beta-cells, binds to the sequence C(C/T)TAATG present at several sites within the human insulin promoter. Here we isolated and sequenced cDNA encoding human IUF1 and exploited it to identify the signal transduction pathway by which glucose triggers its activation. In human islets, or in the mouse beta-cell line MIN6, high glucose induced the binding of IUF1 to DNA, an effect mimicked by serine/threonine phosphatase inhibitors, indicating that DNA binding was induced by a phosphorylation mechanism. The glucose-stimulated binding of IUF1 to DNA and IUF1-dependent gene transcription were both prevented by SB 203580, a specific inhibitor of stress-activated protein kinase 2 (SAPK2, also termed p38 mitogen-activated protein kinase, reactivating kinase, CSBP, and Mxi2) but not by several other protein kinase inhibitors. Consistent with this finding, high glucose activated mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP kinase-2) (a downstream target of SAPK2) in MIN6 cells, an effect that was also blocked by SB 203580. Cellular stresses that trigger the activation of SAPK2 and MAPKAP kinase-2 (arsenite, heat shock) also stimulated IUF1 binding to DNA and IUF1-dependent gene transcription, and these effects were also prevented by SB 203580. IUF1 expressed in Escherichia coli was unable to bind to DNA, but binding was induced by incubation with MgATP, SAPK2, and a MIN6 cell extract, which resulted in the conversion of IUF1 to a slower migrating form. SAPK2 could not be replaced by p42 MAP kinase, MAPKAP kinase-2, or MAPKAP kinase-3. The glucose-stimulated activation of IUF1 DNA binding and MAPKAP kinase-2 (but not the arsenite-induced activation of these proteins) was prevented by wortmannin and LY 294002 at concentrations similar to those that inhibit phosphatidylinositide 3-kinase. Our results indicate that high glucose (a cellular stress) activates SAPK2 by a novel mechanism in which a wortmannin/LY 294002-sensitive component plays an essential role. SAPK2 then activates IUF1 indirectly by activating a novel IUF1-activating enzyme.",
Arsenic,1327131,"Involvement of reactive oxygen species in arsenite-induced downregulation of phospholipid hydroperoxide glutathione peroxidase in human epidermoid carcinoma A431 cells Abstract: Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is unique in the substrate specificity among the glutathione peroxidase family because it can interact with lipophilic substrates, including the peroxidized phospholipids and cholesterol, and reduce these hydroperoxide to hydroxide compounds. However, what kinds of ligand can regulate the PHGPx expression is still unknown. In the present study, we found that sodium arsenite induced downregulation of mRNA, protein expression, and enzyme activity of PHGPx in time- and dose-dependent manners. At the same time, it upregulated mRNA and protein expression of p21(WAF1/CIP1). With the aid of agarose gel electrophoresis, and propidium iodide and annexin-V staining, we found that treatment of 30 microM sodium arsenite for 24 h induced apoptosis in human epidermoid carcinoma A431 cells and EA.hy926 cells. An increase of intracellular peroxide levels was measured by flow cytometry using 2',7'-dichlorofluorescin diacetate (DCFH-DA) after treatment of arsenite. Overexpression of PHGPx prevented arsenite-induced increase of intracellular peroxide levels, downregulation of PHGPx, upregulation of p21(WAF1/CIP1), and apoptosis in A431 cells. N-Acetyl-L-cysteine also significantly prevented arsenite-induced effects in A431 cells. Therefore, we concluded that reactive oxygen species were involved in arsenite-induced downregulation of PHGPx, upregulation of p21(WAF1/CIP1), and apoptosis in A431 cells.",
Arsenic,710798,"An approach to the arsenic status in cardiovascular tissues of patients with coronary heart disease Abstract: Among non-cancer effects of arsenic, cardiovascular diseases have been well documented; however, few are known about the arsenic fate in cardiovascular tissues. We studied the analytic bioinorganic arsenic behaviour in cardiovascular tissues from an arsenic exposure coronary heart disease patient group from Antofagasta-Chile against a small unexposed arsenic coronary heart patient group. Total arsenic concentrations were measured in pieces of cardiovascular tissues of the arsenic-exposed and unexposed coronary heart patient groups by hydride generation atomic absorption spectrometry (HG-AAS); speciation analysis was made by high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Pieces of auricle (AU), mammary artery (MAM), saphenous vein (SAP) and fat residuals (FAT) were considered in this study. The arsenic concentrations in AU and MAM tissues were significantly different between both groups of patients. Also, it was demonstrated that the AU is an 'As(3+) target tissue.' Otherwise, linking of the total concentrations of arsenic with conditional variables and variables related to medical geology factors allowed us to infer that the latter are more important for the cardiovascular risk of arsenic exposure in the Antofagasta region. Knowledge of total arsenic and the prevalence of the trivalent ion (As(3+)) in the AU of patients could contribute to understanding the effect of arsenic on cardiovascular diseases.",
Arsenic,1704145,"Biosorption and bio-kinetic properties of solar saltern halobacterial strains for managing Zn2+, As2+ and Cd2+ metals Abstract: Halobacteria are extreme halophilic archaeobacteria belonging to the family Halobacteriaceae. Geomicrobiologists are concerned about saline tolerant organisms with metal toxicity and bioremediation. Soil samples of Cape comorin coast were analyzed and the zinc, arsenic and cadmium biosorbent halobacterial strains were isolated. Among the fifty-six halobacterial strains isolated, Halobacterium saccharovorum, Hb. salinarium and Natronobacterium gregoryi showed maximum resistance up to 0.01, 0.001 and 0.001 mM against zinc, arsenic and cadmium, respectively. Biokinetic feature such as maximum specific growth rate (?max. d?1), the rate of trace metal removal [s], and half velocity constant [Ks] were calculated. The SEM-EDS pictures show the metal uptake of the halobacterial isolates. It assumes that Hb. saccharovorum, Hb. salinarium and Natronobacterium gregoryi isolated from the salt pan of Rajakkamangalam coast Tamilnadu in India can be used as metals bioremident. Biosorption and Bio-Kinetic Properties of Solar Saltern Halobacterial Strains for Managing Zn2+, As2+ and Cd2+ Metals. Available from: http://www.researchgate.net/publication/263067399_Biosorption_and_Bio-Kinetic_Properties_of_Solar_Saltern_Halobacterial_Strains_for_Managing_Zn2_As2_and_Cd2_Metals [accessed Oct 23, 2015].",
Arsenic,1032264,"The incidence of bladder cancer in the black foot disease endemic area in Taiwan Abstract: A high incidence of bladder cancer (23.53/100,000 population per annum from 1981-1985) was found in an endemic area of peripheral vascular disease known as black foot disease (BFD) on the southwest coast of Taiwan. The average incidence of bladder cancer in the whole of the Taiwan area was 2.29/100,000 during the same period. The incidence of female bladder cancer (21.10/100,000) in this area was also high. The ratio of male to female bladder cancer in the BFD endemic area and the neighbouring area was 1.24 and 1.09, lower than that in the whole Taiwan area (2.75) and elsewhere around the world. The high content of arsenic and the high concentration of a ""fluorescent substance"" in artesian well water in this area are the only 2 related factors identified so far. Determination of the actual carcinogen requires further investigation.",
Arsenic,2337259,"Impact of acute arsenic and cadmium exposure on the expression of two haeme oxygenase genes and other antioxidant markers in common carp (Cyprinus carpio) Abstract: The aim was to study the effects of cadmium (Cd) and arsenic (As) on haeme oxygenases (HOs) and other oxidative stress biomarkers, and their roles in macromolecule damage in liver and kidney of common carp (Cyprinus carpio L.). HOs play a critical role in the defence system against oxidative damage, producing biliverdin and carbon monoxide with important free radical scavenging properties. However, increased HO activity in haeme degradation may also lead to a pro-oxidant effect through the liberation of Fe-modifying Cd and As toxicity. The response of an organism to exposure to toxic metals is in many cases brought about by changes at the level of gene expression. In this study, the genes ho-1 and ho-2 of the common carp were identified, and the changes in gene expressions were analysed from the aspect of Cd and As accumulation. Both ho-1 and ho-2 are transcriptionally induced by Cd and As, but their inductions differ in time course, dose response and tissue specificity. The expression of ho1 was mostly affected by As, primarily in the liver (45-fold), whereas it was enhanced with higher efficacy by Cd in the kidney (25-fold). The cellular redox status and the damage of lipid molecules were monitored via the ratio of reduced to oxidized glutathione, the levels of H2 O2 and lipid peroxidation, and the activities of superoxide dismutase (SOD) and catalase (CAT).",
Arsenic,1349679,"Radioactive elements in natural gas: A case study on distribution of gaseous (222)radon and its origin mechanism Abstract: As natural gas becomes increasingly important in our daily life, studies have been carried out on trace elements such as mercury and arsenic within it. Other than those, the existence of radioactive gaseous radon from the combustion of natural gas indoors can cause severe diseases and damages to body organs, putting a hazardous impact on human health. At the same time, the radon can also corrode gas production and transportation equipment. A review of the literature on radon concentrations in natural gas produced from gas reservoirs in China and other countries have been studied. Radon is a decay product from 238U, which is closely related to the accumulation and migration of organic matter during diagenesis. Gas recovered from reservoirs with higher than average natural 238U contains higher than average levels of 222Rn. Massive fault systems and fracture zones appear to play a significant role in radon concentrations in natural gas.",
Arsenic,1359165,TOXICITY OF ARSENIC AND POLY CHLORINATED BI PHENYLS TO FRY OF DEEP WATER CISCOES COREGONUS Abstract: HEEP COPYRIGHT: BIOL ABS. DDT DDE LC-50,
Arsenic,1030115,"Interactive effects of arsenate, selenium, and dietary protein on survival, growth, and physiology in mallard ducklings Abstract: High concentrations of arsenic (As) and selenium (Se) have been found in aquatic food chains associated with irrigation drainwater. Total biomass of invertebrates, a major source of protein for wild ducklings, may vary in environments that are contaminated with selenium. Day-old mallard (Anas platyrhynchos) ducklings received an untreated diet (controls) containing 22% protein or diets containing 15 ppm Se (as selenomethionine), 60 ppm Se, 200 ppm As (as sodium arsenate), 15 ppm Se with 200 ppm As, or 60 ppm Se with 200 ppm As. In a concurrent experiment, the same sequence was repeated with a protein-restricted (7%) but isocaloric diet. After 4 weeks, blood and tissue samples were collected for biochemical and histological examination. With 22% protein and 60 ppm Se in the diet, duckling survival and growth was reduced and livers had histopathological lesions. Arsenic alone caused some reduction in growth. Antagonistic interactive effects occurred between As and Se, including complete to partial alleviation of the following Se effects: mortality, impaired growth, hepatic lesions and lipid peroxidation, and altered glutathione and thiol status. With 7% protein, survival and growth of controls was less than that with 22% protein, Se (60 ppm) caused 100% mortality, and As (200 ppm) caused mortality, decreased growth, and liver histopathology. These findings suggest the potential for antagonistic effects of Se and As on duckling survival, growth, and physiology with adequate dietary protein but more severe toxicological effects when dietary protein is diminished.",
Arsenic,1018638,"p53 mutations in primary hepatic angiosarcomas not associated with vinyl chloride exposure Abstract: Angiosarcomas of the liver are rare, malignant cancers composed of neoplastic blood vessels. Human hapatic angiosarcomas have been associated with liver cirrhosis or exposure to vinyl chloride, Thorotrast or arsenic. A recent analysis of six hepatic angiosarcomas associated with vinal chloride exposure found three mutations and all were A:T --&gt; T:A transversions, which are otherwise uncommon in human cancers. To test the specificity of this mutation spectrum, we analyzed 21 hepatic angiosarcomas not associated with vinyl chloride exposure. Four cases were exposed to Thorotrast, none had a history of arsenic exposure and the rest were sporadic. Exons 5-8 of the p53 gene were amplified by polymerase chain reaction, and the products were sequenced directly. Two G:C --&gt; A:T transitions were found in two tumors: TGCstop in codon 136. Neither mutation was associated with Thorotrast exposure. These data indicate that p53 mutations are uncommon in sporadic hepatic angiosarcomas (2/21, 9%), and the mutational profile is consistent with endogenous mechanisms. Both features support the evidence linking vinyl chloride exposure to hepatic angiosarcomas containing an increased frequency of p53 mutations with a mutational spectrum (i.e. A:T --&gt; T:A transversions) characteristic of chloroethylene oxide, a carcinogenic metabolite of vinyl chloride.",
Arsenic,1015736,"Dynamic microbial community associated with iron-arsenic co-precipitation products from a groundwater storage system in Bangladesh Abstract: The prokaryotic community in Fe-As co-precipitation product from a groundwater storage tank in Bangladesh was investigated over a 5-year period to assess the diversity of the community and to infer biogeochemical mechanisms that may contribute to the formation and stabilisation of co-precipitation products and to Fe and As redox cycling. Partial 16S rRNA gene sequences from Bacteria and Archaea, functional markers (mcrA and dsrB) and iron-oxidising Gallionella-related 16S rRNA gene sequences were determined using denaturing gradient gel electrophoresis (DGGE). Additionally, a bacterial 16S rRNA gene library was also constructed from one representative sample. Biogeochemical characterization demonstrated that co-precipitation products consist of a mixture of inorganic minerals, mainly hydrous ferric oxides, intimately associated with organic matter of microbial origin that contribute to the chemical and physical stabilisation of a poorly ordered structure. DGGE analysis and polymerase chain reaction-cloning revealed that the diverse bacterial community structure in the co-precipitation product progressively stabilised with time resulting in a prevalence of methylotrophic Betaproteobacteria, while the archaeal community was less diverse and was dominated by members of the Euryarchaeota. Results show that Fe-As co-precipitation products provide a habitat characterised by anoxic/oxic niches that supports a phylogenetically and metabolically diverse group of prokaryotes involved in metal, sulphur and carbon cycling, supported by the presence of Gallionella-like iron-oxidizers, methanogens, methylotrophs, and sulphate reducers. However, no phylotypes known to be directly involved in As(V) respiration or As(III) oxidation were found.",
Arsenic,710840,"Arsenic methylation efficiency increases during the first trimester of pregnancy independent of folate status Abstract: Exposure to inorganic arsenic during pregnancy may negatively influence the offspring, though efficient metabolism of arsenic to dimethylarsinic acid (DMA) likely reduces the health risks. This study aimed to evaluate methylation of arsenic over the entire pregnancy and the influence of nutritional status. We studied longitudinally the arsenic metabolite pattern in the urine of 324 pregnant women exposed to arsenic via drinking water and food in rural Bangladesh. Metabolism of arsenic to DMA increased markedly over the course of pregnancy, with the greatest improvement occurring in the first trimester, along with a marked decrease in the most risk-associated monomethylated metabolite. This improvement in methylation was not associated with nutritional status, including vitamin B(12) and folate. Efficient methylation to DMA was associated with improved urinary excretion of arsenic, relative to blood arsenic concentrations, indicating that micronutrient-independent up-regulation of arsenic metabolism already in early pregnancy may provide protection for the fetus.",
Arsenic,1024370,"Defining and implementing arsenic policies in Bangladesh: possible roles for public and private sector actors Abstract: A UN report warned up to 50% of Bangladesh's population (57 million) are at risk of arsenic poisoning from naturally occurring arsenic in well water. This article explores how this problem occurred, assesses what factors impede progress eliminating this problem and recommends governmental measures for prevention of arsenic poisoning.",
Arsenic,1338817,"Arsenics as bioenergetic substrates Abstract: Although at low concentrations, arsenic commonly occurs naturally as a local geological constituent. Whereas both arsenate and arsenite are strongly toxic to life, a number of prokaryotes use these compounds as electron acceptors or donors, respectively, for bioenergetic purposes via respiratory arsenate reductase, arsenite oxidase and alternative arsenite oxidase. The recent burst in discovered arsenite oxidizing and arsenate respiring microbes suggests the arsenic bioenergetic metabolisms to be anything but exotic. The first goal of the present review is to bring to light the widespread distribution and diversity of these metabolizing pathways. The second goal is to present an evolutionary analysis of these diverse energetic pathways. Taking into account not only the available data on the arsenic metabolizing enzymes and their phylogenetical relatives but also the palaeogeochemical records, we propose a crucial role of arsenite oxidation via arsenite oxidase in primordial life. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetics systems.",
Arsenic,1015735,"New clusters of arsenite oxidase and unusual bacterial groups in enrichments from arsenic-contaminated soil Abstract: In the present study cultivation-dependent and molecular methods were applied in combination to investigate the arsenite-oxidizing communities in enrichment cultures from arsenic and lead smelter-impacted soils with respect to both 16S rRNA and arsenite oxidase gene diversity. Enrichments with arsenite as the only electron donor resulted in completely different communities than enrichments with yeast extract and the simultaneous presence of arsenite. The lithoautotrophic community appeared to be dominated by Ferrimicrobium-related Actinobacteria, unusual Acidobacteria, Myxobacteria, and ?-Proteobacteria but the heterotrophic community comprised many Dokdonella-related ?-Proteobacteria. Gene sequences of clones encoding arsenite oxidase from the enrichment for lithoautotrophs belonged to three major clusters with sequences from non-cultivated microorganisms. So, primers used to detect arsenite oxidase genes could amplify the genes from many ?-, ?- and ?-Proteobacteria, but not from various strains of the other phyla present in the enrichment for lithotrophs. This was also observed for the isolates where arsenite oxidase genes from new proteobacterial isolates of the genera Burkholderia, Bosea, Alcaligenes, Bradyrhizobium and Methylobacterium could be amplified but the genes of the new Rhodococcus isolate S43 could not. The results indicate that the ability to oxidize arsenite is widespread in various unusual taxa, and molecular methods for their detection require further improvement.",
Arsenic,1252337,"The Rönnskär Smelter–Occupational and environmental effects in and around a polluting industry in northern Sweden Abstract: Research on occupational and environmental pollution from a copper (7440508) smelter (SIC-3331) in northern Sweden is reviewed. The smelter processes a complex ore with a high arsenic (7440382) content, produces copper, lead (7439921), and a series of other products. Emissions studies show air emissions average 50 tons/year arsenic, 200 tons/year lead, 5 tons/year cadmium (7440439), and 1 ton/year mercury (7439976). Effects of airborne pollutants on lakes at various distances from the smelter, show elevated concentrations of heavy metals (5 to 40 times normal) within 10 kilometers (km) of the smelter. Heavy metal concentrations are also increased in soils at distances of 15 to 25km and in barley, potatoes, berries, and vegetables. Studies of urinary lead, cadmium, and mercury in females at various distances from the smelter show no significant differences; however, urinary arsenic concentrations are significantly elevated in females located south (the direction of the prevailing winds) of the smelter. Significant increases in blood lead concentrations are also reported in males living near the smelter, but these correlate more particularly with occupational exposures. Mortality studies suggest an excess of lung cancer in the area, again correlated with occupational (smelter) exposure rather than environmental contamination. A case/reference study of smelter workers further substantiates the effect of arsenic exposure, showing increased lung cancer and cardiovascular mortality among workers. Increased chromosomal damage is also demonstrated in smelter workers with high and medium lead and arsenic exposures. Increased abortion rates are revealed among exposed female workers, particularly if their husbands are also smelter workers. Decreasing birth weight with birth order is demonstrated in the vicinity of the smelter. Studies also suggest an increase in congenital malformations among smelter workers but not among nearby residents. The author concludes that occupational exposures, particularly to lead and arsenic, produce definite health and reproductive risks, but environmental hazards are not clearly demonstrated.",
Arsenic,1032541,"Differential cytotoxicity of sodium arsenite in human fibroblasts and Chinese hamster ovary cells Abstract: Human skin fibroblast (HF) cells were approximately 10-fold more sensitive to sodium arsenite toxicity than Chinese hamster ovary (CHO) cells using the clonogenic assay. G1-phase CHO cells showed a 2-fold increase in the susceptibility to the toxic effects of sodium arsenite as compared to asynchronous CHO cells. The concentrations of sodium arsenite required to kill 50% of the cell population were correlated with the intracellular glutathione levels in asynchronous, G1-phase CHO, and asynchronous HF cells. Moreover, verapamil potentiated the cytotoxicity of sodium arsenite in CHO cells but not in HF cells. These results indicated that a verapamil-sensitive outward channel may be involved in detoxification of arsenic in CHO cells. Treatment with sodium arsenite resulted in a marked cell-cycle disturbance in CHO, but not in HF cells. Thus, CHO cells may take time to recover from sodium arsenite insult before progressing through the cell cycle. A different response of sodium arsenite in heat-shock protein synthesis in these 2 cell types was also revealed.",
Arsenic,627135,"Association of arsenic-contaminated drinking-water with prevalence of skin cancer in Wisconsin's Fox River Valley Abstract: During July 2000-January 2002, the Wisconsin Division of Public Health conducted a study in 19 rural townships. A high percentage of private drinking-water wells in these townships contained traces of arsenic. Residents were asked to collect well-water samples and complete a questionnaire regarding residential history, consumption of drinking-water, and family health. In total, 2,233 household wells were tested, and 6,669 residents, aged less than one year to 100 years, provided information on water consumption and health. The well-water arsenic levels ranged from less than 1.0 to 3,100 microg/L. The median arsenic level was 2.0 microg/L. The arsenic levels were below the federal drinking-water standard of 10 microg/L in 80% of the wells, while 11% had an arsenic level of above 20 microg/L. Of residents aged over 35 years, those who had consumed arsenic-contaminated water for at least 10 years were significantly more likely to report a history of skin cancer than others. Tobacco use was also associated with higher rates of skin cancer and appeared to synergize the effect of arsenic on the development of skin cancer.",
Arsenic,1352932,Phosphate has a differential influence on arsenate adsorption by soils with different properties Abstract: ,
Arsenic,1797771,"Speciation and toxicity of arsenic in mining-affected lake sediments in the Quinsam watershed, British Columbia Abstract: Anthropogenic arsenic inputs into fresh water lakes in the Quinsam watershed, British Columbia, were probed by using multiple methods of inquiry including sediment coring combined with (210)Pb dating, a principal components analysis of elemental composition of sediments, arsenic speciation, bioaccessibility, and toxicity testing. The quantification of arsenic inputs from anthropogenic sources was not trivial because a variety of processes redistribute the element throughout lakes. However, elevated arsenic and sulfate concentrations in Long Lake, a lake that receives arsenic from a seep, suggest that this lake is influenced by mine operations. X-ray absorption near edge structure (XANES) spectra reveal similar arsenic speciation for all sediments within the studied lakes. Bioaccessibility tests, which in this study were used to approximate the solubility and availability of arsenic to benthic organisms, indicate moderate bioaccessibility of arsenic in sediments (7.9-35%). Toxicity testing indicates that not all benthic organisms should be used for evaluating arsenic toxicity, and suggests that the amphipod, Corophium volutator, shows promise as a candidate for widespread use for arsenic sediment toxicity testing.",
Arsenic,1022934,"Opposed arsenite-induced signaling pathways promote cell proliferation or apoptosis in cultured lung cells Abstract: Arsenic is a well-known carcinogen that possibly promotes tumors and the development of various types of cancer in individuals chronically exposed to arsenic in their work or living environment. Many studies have demonstrated the activation of mitogen-activated protein kinase (MAPK) in several cell types by using lethal concentrations of arsenic in the range of 50-500 micro M. Since the exposure of humans to arsenic is normally at a much lower level in the workplace or in daily life, it is more relevant to study the effects of arsenic at this lower exposure level. In the present study we aimed at redefining the role of signal transduction pathways in arsenic-induced malignant transformation as well as apoptosis using our established in vitro rat lung epithelial cell model system. Our results indicate a molecular mechanism by which MAPK pathways might differentially contribute to cell growth regulation and cell death in response to different dosages of arsenite. A low level (2 micro M) of arsenite stimulated extracellular signal-regulated kinase (ERK) signaling pathway and enhanced cell proliferation, and this arsenite-induced ERK activity was blocked by MEK inhibitor, PD98059. In contrast, a high level (40 micro M) of arsenite stimulated the c-Jun N-terminal kinase (JNK) signaling pathway and induced cell apoptosis, and this arsenite-induced JNK activity was blocked by JNK inhibitor II, SP600125. The implications of these findings are that a high concentration of arsenic exposure causes apoptosis, whereas a low concentration of arsenic exposure is carcinogenic and may result in aberrant cell accumulation.",
Arsenic,1381495,"Experiments on the chemoprophylaxis of Onchocerca volvulus infection Abstract: Previous work on monkeys and on human volunteers led to the development of a schedule of diethylcarbamazine dosage suitable for the chemoprophylaxis of loiasis. In several parts of Africa where this chemoprophylaxis is practised against Loa loa, infections with Onchocerca volvulus are also common. Attempts were therefore made to determine whether diethylcarbamazine has any prophylactic action against the latter parasite by making use of chimpanzees exposed to experimental infections, and also by using biopsy techniques to study the fate of infective larvae inoculated into volunteers.Both experimental methods proved more difficult to apply in O. volvulus infections than had been the case with L. loa, but evidence was obtained that diethylcarbamazine is not an effective chemoprophylactic for O. volvulus.Further experiments were then carried out with suramin and with melarsonyl potassium (Mel W). Although both gave some evidence of partial prophylactic activity, their use for this purpose is at present neither practical nor safe.",
Arsenic,1508660,"Arsenic and the epigenome: Interindividual differences in arsenic metabolism related to distinct patterns of DNA methylation Abstract: Biotransformation of inorganic arsenic (iAs) is one of the factors that determines the character and magnitude of the diverse detrimental health effects associated with chronic iAs exposure, but it is unknown how iAs biotransformation may impact the epigenome. Here, we integrated analyses of genome-wide, gene-specific promoter DNA methylation levels of peripheral blood leukocytes with urinary arsenical concentrations of subjects from a region of Mexico with high levels of iAs in drinking water. These analyses revealed dramatic differences in DNA methylation profiles associated with concentrations of specific urinary metabolites of arsenic (As). The majority of individuals in this study had positive indicators of As-related disease, namely pre-diabetes mellitus or diabetes mellitus (DM). Methylation patterns of genes with known associations with DM were associated with urinary concentrations of specific iAs metabolites. Future studies will determine whether these DNA methylation profiles provide mechanistic insight into the development of iAs-associated disease, predict disease risk, and/or serve as biomarkers of iAs exposure in humans.",
Arsenic,2149359,"COMPARISION OF SLAUGHTER YIELD, CONTENTS OF BASIC NUTRIENTS, AND LEVELS OF HEAVY METALS IN MUSCLES OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) ORIGINATING FROM VARIOUS REGIONS IN POLAND Abstract: ",
Arsenic,1032644,"Immunological profiles in workers of a power plant burning coal rich in arsenic content Abstract: A group of 47 male adults working in a thermal power plant burning coal containing 900 to 1,500 g of arsenic per ton dry weight was examined on the blood serum immunoglobulins IgG, IgA and IgM content and levels of acute reactants alpha-1-antitrypsin (A1AT), alpha-2-macroglobulin (A2M), transferrin (TRF), orosomucoid (ORO) ceruloplasmin (CPL), and lysozyme (LYS). Investigations in the control group comprising 27 workers from another power plant in the same district where the coal content of arsenic was more than 10 times lower were analogous. The inter-group differences in means were evaluated by t-test, differences in the association of values by F-test, and the correlations with age and the length of exposure were assessed using the regression analysis method. The differences in mean IgG, IgA, IgM, LYS and A2M levels between the exposed and control groups of workers were insignificant or of borderline significance only. In contrast, differences in TRF, ORO and particularly CPL levels were statistically highly significant, in all instances P less than 0.001. In the control group, persons with abnormal values in at least two immunobiochemical tests used accounted for 3.7%, in the group of the exposed for 51% (P less than 0.002). All these findings, especially the rise in CPL concentration levels in the exposed group are discussed on the background of the rise in cancer mortality rates found previously in this group of power plant workers.",
Arsenic,1343518,"Hydrogeochemical study on the contamination of water resources in a part of Tarkwa mining area, Western Ghana Abstract: The aim of this study was to investigate the groundwater chemistry with special concern to metal pollution in selected communities in the Wassa West district, Ghana. In this mining area, 40 ground water samples, mainly from drilled wells, were collected. The groundwaters have generally from neutral to acidic pH values and their Eh values indicate oxidising conditions. The dominating ions are calcium, sodium, and bicarbonate. The metal concentrations in the study area are generally lower than those typically found in mining regions. Only 17 wells show metal concentrations exceeding WHO guidelines for at least one metal. The main contaminants are manganese and iron, but arsenic and aluminium also exceed the guidelines in some wells probably affected by acid mine drainage (AMD). Metal concentrations in the groundwater seem to be controlled by the adsorption processes. Hydrogeochemical modelling indicates supersaturation of groundwater with respect to several mineral phases including iron-hydroxides/oxides, suggesting that adsorption on these minerals may control heavy metal and arsenic concentrations in groundwater. The area is hilly, with many groundwater flow divides that result in several local flow systems. The aquifers therefore are not strongly affected by weathering of minerals due to short groundwater residence times and intense flushing. The local character of groundwater flow systems also prevents a strong impact of acid mine drainage on groundwater systems in a regional scale.",
Arsenic,2279321,"Enhanced antitumor activity of realgar mediated by milling it to nanosize Abstract: Realgar is a poorly water-soluble compound that exhibits poor bioavailability. To improve this, the authors reduced the particle size of realgar to nanoscale by high-energy ball milling and optimized the preparation process under which (realgar weight 40 g, milling time 9 hours, milling speed 38 Hz, milling temperature -20°C) realgar nanoparticles (NPs) with an average size of 78±8.3 nm were prepared. The average particle size of realgar was characterized by laser scattering, and its apparent shape was observed by transmission electron microscopy and scanning electron microscopy. The solubility of realgar was enhanced after milling until the particles were in the nanoscale region without altering its properties, as confirmed by a scanning electron microscopy energy-dispersive spectrometer. Realgar NPs had higher cytotoxicity on the selected cell lines, namely human breast cancer (MCF7), human hepatoma (HepG2), and human lung cancer (A549) cell lines, than coarse realgar. In addition, a pharmacokinetics study performed in rats indicated that the relative bioavailability of realgar NPs was 216.9% compared with coarse realgar; a biodistribution study performed in mice showed that after intragastric administration of realgar NPs, higher arsenic concentration was reached in the tumor, heart, liver, spleen, lung, and kidney compared with the administration of coarse realgar, as confirmed by inductively coupled plasma mass spectrometry to determine the concentration of arsenic. This study indicated that high-energy ball milling is an effective way to reduce the average particle size of realgar, and compared with coarse realgar, the cytotoxicity and bioavailability of realgar NPs were significantly improved.",
Arsenic,2345651,"Metal concentrations in surface water and sediments from Pardo River, Brazil: Human health risks Abstract: Pardo River (Brazil) is suffering from an important anthropogenic impact due to the pressure of highly populated areas and the influence of sugarcane cultivation. The objective of the present study was to determine the levels of 13 trace elements (As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V and Zn) in samples of surface water and sediments from the Pardo River. Furthermore, the human health risks associated with exposure to those metals through oral intake and dermal absorption were also evaluated. Spatial and seasonal trends of the data were closely analyzed from a probabilistic approach. Manganese showed the highest mean concentrations in both water and sediments, remarking the incidence of the agricultural activity and the geological characteristics within the basin. Thallium and arsenic were identified as two priority pollutants, being the most important contributors to the Hazard Index (HI). Since non-carcinogenic risks due to thallium exposure slightly exceeded international guidelines (HI>1), a special effort should be made on this trace element. However, the current concentrations of arsenic, a carcinogenic element, were in accordance to acceptable lifetime risks. Nowadays, there is a clear increasing growth in human population and economic activities in the Pardo River, whose waters have become a serious strategic alternative for the potential supply of drinking water. Therefore, environmental monitoring studies are required not only to assure that the current state of pollution of Pardo River does not mean a risk for the riverside population, but also to assess the potential trends in the environmental levels of those elements.",
Arsenic,1329919,"Reactive oxygen species as a signal in glucose-stimulated insulin secretion Abstract: One of the unique features of beta-cells is their relatively low expression of many antioxidant enzymes. This could render beta-cells susceptible to oxidative damage but may also provide a system that is sensitive to reactive oxygen species as signals. In isolated mouse islets and INS-1(832/13) cells, glucose increases intracellular accumulation of H2O2. In both models, insulin secretion could be stimulated by provision of either exogenous H2O2 or diethyl maleate, which raises intracellular H2O2 levels. Provision of exogenous H2O2 scavengers, including cell permeable catalase and N-acetyl-L-cysteine, inhibited glucose-stimulated H2O2 accumulation and insulin secretion (GSIS). In contrast, cell permeable superoxide dismutase, which metabolizes superoxide into H2O2, had no effect on GSIS. Because oxidative stress is an important risk factor for beta-cell dysfunction in diabetes, the relationship between glucose-induced H2O2 generation and GSIS was investigated under various oxidative stress conditions. Acute exposure of isolated mouse islets or INS-1(832/13) cells to oxidative stressors, including arsenite, 4-hydroxynonenal, and methylglyoxal, led to decreased GSIS. This impaired GSIS was associated with increases in a battery of endogenous antioxidant enzymes. Taken together, these findings suggest that H2O2 derived from glucose metabolism is one of the metabolic signals for insulin secretion, whereas oxidative stress may disturb its signaling function.",
Arsenic,1015815,"[6]-Gingerol isolated from ginger attenuates sodium arsenite induced oxidative stress and plays a corrective role in improving insulin signaling in mice Abstract: Arsenic toxicity induces type 2 diabetes via stress mediated pathway. In this study, we attempt to reveal how sodium arsenite (iAs) could induce stress mediated impaired insulin signaling in mice and if an isolated active fraction of ginger, [6]-gingerol could attenuate the iAs intoxicated hyperglycemic condition of mice and bring about improvement in their impaired insulin signaling. [6]-Gingerol treatment reduced elevated blood glucose level and oxidative stress by enhancing activity of super oxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and GSH. [6]-Gingerol also helped in increasing plasma insulin level, brought down after iAs exposure. iAs treatment to primary cell culture of ?-cells and hepatocytes in vitro produced cyto-degenerative effect and accumulated reactive oxygen species (ROS) in pancreatic ?-cells and hepatocytes of mice. [6]-Gingerol appeared to inhibit/intervene iAs induced cyto-degeneration of pancreatic ?-cells and hepatocytes, helped in scavenging the free radicals. The over-expression of TNF? and IL6 in iAs intoxicated mice was down-regulated by [6]-gingerol treatment. iAs intoxication reduced expression levels of GLUT4, IRS-1, IRS-2, PI3K, AKT, PPAR? signaling molecules; [6]-gingerol mediated its action through enhancing the expressions of these signaling molecules, both at protein and mRNA levels. Thus, our results suggest that [6]-gingerol possesses an anti-hyperglycemic property and can improve impaired insulin signaling in arsenic intoxicated mice.",
Arsenic,1508583,"A high intake of dietary fiber influences C-reactive protein and fibrinogen, but not glucose and lipid metabolism, in mildly hypercholesterolemic subjects Abstract: PURPOSE: The aim of the study was to investigate how a diet high in dietary fiber, with several fiber sources included, modulates glucose and lipid metabolism and the inflammatory response in humans. METHODS: Subjects (n = 25) aged 58.6 (1.1) years (mean and SD) with a BMI of 26.6 (0.5) kg/m(2) and a total cholesterol (TC) of 5.8 (0.1) mmol/L (mean and SEM) were given a high fiber (HF) and low fiber (LF) diet, in a randomized controlled 5-week crossover intervention, separated by a 3-week washout. The HF diet consisted of oat bran, rye bran, and sugar beet fiber incorporated into test food products; one bread roll, one ready meal, and two beverages consumed daily. Equivalent food products, without added fibers, were provided in the LF diet. RESULTS: Total dietary fiber intake was 48.0 g and 30.2 g per day for the HF and LF diet, respectively. Significant reduction in C-reactive protein (CRP) was observed between the diets (P = 0.017) and a significant reduction in fibrinogen within the HF diet (P = 0.044). There were no significant effects in other measured circulating cytokines or in glucose, insulin, and lipid levels. CONCLUSIONS: Our study suggests that a 5-week high dietary fiber intake of oat bran, rye bran, and sugar beet fiber might reduce the low-grade inflammatory response measured as CRP which could, together with reduced fibrinogen, help to prevent the risk of cardiovascular disease.",
Arsenic,1015844,"A modified Langmuir-Freundlich isotherm model for simulating pH-dependent adsorption effects Abstract: Analytical isotherm equations such as Langmuir and Freundlich isotherms are widely used for modeling adsorption data. However, these isotherms are primarily useful for simulating data collected at a fixed pH value and cannot be easily adapted to simulate pH-dependent adsorption effects. Therefore, most adsorption studies currently use numerical surface-complexation models (SCMs), which are more complex and time consuming than traditional analytical isotherm models. In this work, we propose a new analytical isotherm model, identified as the modified Langmuir-Freundlich (MLF) isotherm, which can be used to simulate pH-dependent adsorption. The MLF isotherm uses a linear correlation between pH and affinity coefficient values. We validated the proposed MLF isotherm by predicting arsenic adsorption onto two different types of sorbents: pure goethite and goethite-coated sand. The MLF model gave good predictions for both experimental and surface complexation-model predicted datasets for these two sorbents. The proposed analytical isotherm framework can help reduce modeling complexity, model development time, and computational efforts. One of the limitations of the proposed method is that it is currently valid only for single-component systems. Furthermore, the model requires a system-specific pH. vs. affinity coefficient relation. Despite these limitations, the approach provides a promising analytical framework for simulating pH-dependent adsorption effects.",
Arsenic,1519246,"Synthesis of zero valent iron nanoparticles and application to removal of arsenic(III) and arsenic(V) from water Abstract: Recently nano scale zero valent iron particles (nZVI) have been considered as smart adsorbent for environmental and groundwater remediation. Although several synthetic methods are available for the preparation of nZVI, air stable nZVI are not available for remediation works. Further, challenges demand synthesis of nZVI without stabilizers and capping agents. A modified methodology for the synthesis of air stable nZVI has been developed without any capping agents and characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy Energy-dispersive X-Ray (SEM-EDS), Transmission Electron Microscopy (TEM) and X-Ray Photoelectron Spectroscopy (XPS). The results of the present study suggest that the synthetic nZVI are air-stable over a period of one year and consists of particles of 30-40 nm in diameter. Although a layer of less than 3 am thick oxide/hydroxide is observed by TEM and XPS, it appears to be due to oxidation of outer surface during analysis. Adsorption study has shown that the synthetic nZVI are more effective adsorbent than the commercial nZVI and can remove simultaneously arsenite [As-III] and arsenate [As-V] from water without prior reduction of As-V to As-III. The removal process is adsorptive rather than precipitative and the removal of As-III is greater than that of As-V.",
Arsenic,2343430,"Chronic low-level arsenic exposure reduces lung function in male population without skin lesions Abstract: <strong>OBJECTIVES: </strong>The respiratory effects of chronic low-level arsenic exposure from groundwater have been investigated in West Bengal, India.<br /><br /><strong>METHODS: </strong>The participants (834 non-smoking adult males) were subdivided in two groups: an arsenic-exposed group (n = 446, mean age 35.3 years) drinking arsenic-contaminated groundwater (11-50 ?g/L) and a control group of 388 age-matched men drinking water containing &lt;10 ?g/L of arsenic. Arsenic in water samples was measured by atomic absorption spectroscopy. The prevalence of respiratory symptoms was documented by structured, validated questionnaire. Pulmonary function test (PFT) was assessed by portable spirometer.<br /><br /><strong>RESULTS: </strong>Compared with control, the arsenic-exposed subjects had higher prevalence of upper and lower respiratory symptoms, dyspnea, asthma, eye irritation and headache. Besides, 20.6 % of arsenic-exposed subjects had lung function deficits (predominantly restrictive and combined types) compared with 13.6 % of control (p &lt; 0.05). A positive association was observed between arsenic concentration in drinking water and the prevalence of respiratory symptoms, while a negative association existed between arsenic level and spirometric parameters.<br /><br /><strong>CONCLUSIONS: </strong>The findings suggest that even low-level arsenic exposure has deleterious respiratory effects.",
Arsenic,1508718,"Adjuvant docetaxel, doxorubicin, and cyclophosphamide in node-positive breast cancer: 10-year follow-up of the phase 3 randomised BCIRG 001 trial Abstract: <strong>BACKGROUND: </strong>We compared standard adjuvant anthracycline chemotherapy with anthracycline-taxane combination chemotherapy in women with operable node-positive breast cancer. Here we report the final, 10-year follow-up analysis of disease-free survival, overall survival, and long-term safety.<br /><br /><strong>METHODS: </strong>BCIRG 001 was an open label, phase 3, multicentre trial in which 1491 patients aged 18-70 years with node-positive, early breast cancer and a Karnofsky score of 80% or more were randomly assigned to adjuvant treatment with docetaxel, doxorubicin, and cyclophosphamide (TAC) or fluorouracil, doxorubicin, and cyclophosphamide (FAC) every 3 weeks for six cycles. Randomisation was stratified according to institution and number of involved axillary lymph nodes per patient (one to three vs four or more). Disease-free survival was the primary endpoint and was defined as the interval between randomisation and breast cancer relapse, second primary cancer, or death, whichever occurred first. Efficacy analyses were based on the intention-to-treat principle. BCIRG 001 is registered with ClinicalTrials.gov, number NCT00688740.<br /><br /><strong>FINDINGS: </strong>Enrolement took place between June 11, 1997 and June 3, 1999; 745 patients were assigned to receive TAC and 746 patients were assigned to receive FAC. After a median follow-up of 124 months (IQR 90-126), disease-free survival was 62% (95% CI 58-65) for patients in the TAC group and 55% (51-59) for patients in the FAC group (hazard ratio [HR] 0·80, 95% CI 0·68-0·93; log-rank p=0·0043). 10-year overall survival was 76% (95% CI 72-79) for patients in the TAC group and 69% (65-72) for patients in the FAC group (HR 0·74, 0·61-0·90; log-rank p=0·0020). TAC improved disease-free survival relative to FAC irrespective of nodal, hormone receptor, and HER2 status, although not all differences were significant in these subgroup analyses. Grade 3-4 heart failure occurred in 26 (3%) patients in the TAC group and 17 (2%) patients in the FAC group, and caused death in two patients in the TAC group and four patients in the FAC group. A substantial decrease in left ventricular ejection fraction (defined as a relative decrease from baseline of 20% or more) was seen in 58 (17%) patients who received TAC and 41 (15%) patients who received FAC. Six patients who received TAC developed leukaemia or myelodysplasia, as did three patients who received FAC.<br /><br /><strong>INTERPRETATION: </strong>Our results provide evidence that the initial therapeutic outcomes seen at the 5-year follow-up with a docetaxel-containing adjuvant regimen are maintained at 10 years. However, a substantial percentage of patients had a decrease in left ventricular ejection fraction, probably caused by anthracycline therapy, which warrants further investigation.",
Arsenic,1003593,"In vitro development of resistance to arsenite and chromium-VI in Lactobacilli strains as perspective attenuation of gastrointestinal disorder Abstract: Inadvertent intake of inorganic arsenic and chromium through drinking water and food causing their toxic insults is a major health problem. Intestinal bacteria including Lactobacilli play important regulatory roles on intestinal homeostasis, and their loss is known to cause gastrointestinal (GI) disorders. Probiotic Lactobacilli resistance to arsenite and chromium-VI could be an importantfactorfor the perspective attenuation of Gl-disorders caused by these toxic metals/metalloid. In the present study resistance of arsenite (up to 32 ppm), Cr-VI (up to 64 ppm), and arsenite plus Cr-VI (32 ppm each) were developed under in vitro condition following chronological chronic exposures in Lactobacilli strains. Comparative study of biochemical parameters such as membrane transport enzymes and structural constituents; dehydrogenase and esterase activity tests, which are respective indicators for respiratory and energy producing processes, and the general heterotrophic activity of cells, of resistant strains showed similarities with their respective normal parent strains. The resistant strains were also found to be sensitive to antibiotics. Findings indicate that these resistant probiotic Lactobacilli would be useful in the prophylactic interventions of arsenic and chromium GI-toxicity.",
Arsenic,627934,"Induction of chromosome breaks in cultured normal human leukocytes by potassium arsenite, hydroxyurea and related compounds Abstract: Hydroxyurea and N-hydroxyurethane at mm concentrations produced a high incidence of chromosome breaks along with other signs of cell toxicity in short-term cultures of phytohemagglutinin-stimulated normal human leukocytes. Chromosome rearrangements as well as breaks were produced by µm levels of potassium arsenite, suggesting that interference with oxidative phosphorylation can result in chromosome fragmentation. Acetohydroxamic acid and hydroxylamine both resulted in signs of cell injury but no significant chromosomal damage at µm concentrations. Urea, although inactive at physiologic concentrations, at 50 mm produced marked chromosomal fragmentation and evidence of cytoxicity.",
Arsenic,628634,"Oxidative DNA damage in relation to neurotoxicity in the brain of mice exposed to arsenic at environmentally relevant levels Abstract: To clarify the association between oxidative DNA damage and the neurotoxicity of arsenic, the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) as an index of oxidative DNA damage in the brain was examined in mice fed with drinking water containing 1 or 2 ppm arsenic, using an HPLC-electrochemical detector and immunohistochemical method. 8-OHdG levels were significantly increased in the brain of mice given arsenic and its immunoreactivity was distributed in the cerebral and cerebellar cortexes. Cerebral cortex neurons and Purkinje cells in the cerebellar cortex showed degenerative changes in accordance with the distribution of 8-OHdG immunoreactivity. The levels of arsenic in this study were lower than those reported in epidemiological studies. Thus, we conclude that environmentally relevant levels of arsenic induce pathological changes through oxidative DNA damage in the brain tissues in vivo and that cerebral and cerebellar cortex neurons seem to be the major targets of arsenic neurotoxicity.",
Arsenic,90072,"Some effects of cigarette smoking, arsenic, and SO2 on mortality among US copper smelter workers Abstract: Previous studies of the relationship between arsenic levels and respiratory cancer among copper smelter workers have not directly accounted for possible effects of SO2 exposure and cigarette smoking. This is a report on the 1949-1980 mortality experience of 6,078 white male workers who worked at least 3 years between 1 January 1946 and 31 December 1976 at one or more of eight US copper smelters. The completeness of the cohort was verified statistically, and worker exposures to arsenic, SO2, dust, nickel, cadmium, and lead were estimated from retrospective industrial hygiene surveys reported elsewhere. By using internal controls, a dose-response relationship for lung cancer was observed with exposure to arsenic and SO2. When cigarette smoking data were included with arsenic and SO2 exposure data in a nested case-control analysis, only smoking and arsenic were statistically significant factors. The arsenic-lung cancer relationship was confined to a single smelter associated with high content feed. In the remaining smelters mortality for all causes of death and for all cancer was not high based on comparisons with national, state, and local rates.",
Arsenic,2337277,"The impacts of different long-term fertilization regimes on the bioavailability of arsenic in soil: Integrating chemical approach with Escherichia coli arsRp::luc-based biosensor Abstract: An Escherichia coli arsRp::luc-based biosensor was constructed to measure the bioavailability of arsenic (As) in soil. In previous induction experiments, it produced a linear response (R (2)?=?0.96, P?&lt;?0.01) to As from 0.05 to 5 ?mol/L after a 2-h incubation. Then, both chemical sequential extraction, Community Bureau of Reference recommended sequential extraction procedures (BCR-SEPs) and E. coli biosensor, were employed to assess the impact of different long-term fertilization regimes containing N, NP, NPK, M (manure), and NPK?+?M treatments on the bioavailability of arsenic (As) in soil. Per the BCR-SEPs analysis, the application of M and M?+?NPK led to a significant (P?&lt;?0.01) increase of exchangeable As (2-7 times and 2-5 times, respectively) and reducible As (1.5-2.5 times and 1.5-2.3 times, respectively) compared with the no fertilization treated soil (CK). In addition, direct contact assay of E. coli biosensor with soil particles also supported that bioavailable As in manure-fertilized (M and M?+?NPK) soil was significantly higher (P?&lt;?0.01) than that in CK soil (7 and 9 times, respectively). Organic carbon may be the major factor governing the increase of bioavailable As. More significantly, E. coli biosensor-determined As was only 18.46-85.17 % of exchangeable As and 20.68-90.1 % of reducible As based on BCR-SEPs. In conclusion, NKP fertilization was recommended as a more suitable regime in As-polluted soil especially with high As concentration, and this E. coli arsRp::luc-based biosensor was a more realistic approach in assessing the bioavailability of As in soil since it would not overrate the risk of As to the environment.",
Arsenic,628085,"Association of chromosomal alterations with arsenite-induced tumorigenicity of human HaCaT keratinocytes in nude mice Abstract: Inorganic arsenic is a well-documented human carcinogen. Chronic low-dose exposure to inorganic arsenic is associated with an increased incidence of a variety of cancers, including skin, lung, bladder, and liver cancer. Because genetic alterations often occur during cancer development, the objective of this study was to explore what types of genetic alterations were induced by chronic exposure of human HaCaT cells to arsenic. After 20 passages in the presence of inorganic trivalent arsenite at concentrations of 0.5 or 1 microM, HaCaT cells had higher intracellular levels of glutathione, became more resistance to arsenite, and showed an increased frequency of micronuclei. Furthermore, the previously nontumorigenic HaCaT cells became tumorigenic, as shown by subcutaneous injection into Balb/c nude mice. Cell lines derived from the tumors formed by injection of arsenite-exposed HaCaT cells into nude mice expressed higher levels of keratin 6, a proliferation marker of keratinocytes, than did parental HaCaT cells, whereas the expression of keratins 5, 8, and 10 was significantly decreased. Comparative genomic hybridization demonstrated chromosomal alterations in the 11 cell lines derived from these tumors; all 11 showed significant loss of chromosome 9q, and seven showed significant gain of chromosome 4q. The present results show that long-term exposure to low doses of arsenite transformed nontumorigenic human keratinocytes to cells that were tumorigenic in nude mice and that chromosomal alterations were observed in all cell lines established from the tumors.",
Arsenic,1374823,"Induction of thermotolerance and heat shock protein synthesis in normal and respiration-deficient chick embryo fibroblasts Abstract: Normal and transformed chick embryo cells and their respective ethidium bromide-treated derivatives that are devoid of a functional respiratory chain were comparatively evaluated for their responses to hyperthermia treatment. No significant difference was found between the control and the respiration-deficient cells. The cells have a similar intrinsic thermosensitivity as judged by their capacity to form colonies after treatment at supraoptimal temperatures, and heat triggers in both cases an equal production of heat shock proteins and a strong induction of thermotolerance. In addition, sodium arsenite, carbonyl cyanide m-chlorophenylhydrazone, oligomycin, and antimycin A induce a similar heat shock protein response in the control and the treated cells. Based on these results, it is concluded that the inhibition by heat of the mitochondrial energy production does not constitute an obligatory rate-limiting event in hyperthermic cell killing and that the intracellular signal triggering development of thermotolerance or heat shock protein production does not obligatorily originate from damages to the respiratory chain. Moreover, the results indicate that the modifications responsible for the increased heat resistance of thermotolerant cells may not, or do not necessarily, involve a stabilization of the mitochondrial energy production.",
Arsenic,1026588,"Applying a health behavior theory to explore the influence of information and experience on arsenic risk representations, policy beliefs, and protective behavior Abstract: The common sense model (CSM) shows how people process information to construct representations, or mental models, that guide responses to health threats. We applied the CSM to understand how people responded to information about arsenic-contaminated well water. Constructs included external information (arsenic level and information use), experience (perceived water quality and arsenic-related health effects), representations, safety judgments, opinions about policies to mitigate environmental arsenic, and protective behavior. Of 649 surveys mailed to private well users with arsenic levels exceeding the maximum contaminant level, 545 (84%) were analyzed. Structural equation modeling quantified CSM relationships. Both external information and experience had substantial effects on behavior. Participants who identified a water problem were more likely to reduce exposure to arsenic. However, about 60% perceived good water quality and 60% safe water. Participants with higher arsenic levels selected higher personal safety thresholds and 20% reported a lower arsenic level than indicated by their well test. These beliefs would support judgments of safe water. A variety of psychological and contextual factors may explain judgments of safe water when information suggested otherwise. Information use had an indirect effect on policy beliefs through understanding environmental causes of arsenic. People need concrete information about environmental risk at both personal and environmental-systems levels to promote a comprehensive understanding and response. The CSM explained responses to arsenic information and may have application to other environmental risks.",
Arsenic,1021614,"Metal accumulation in the tissues of grass carps (Ctenopharyngodon idellus) from fresh water around a copper mine in Southeast China Abstract: Mining effluents are the main source of metals in the surrounding aquatic environment. The mining district of Purple Mountain has a history of copper mining for more than 30 years, but there is limited investigation of metal bioaccumulation in the aquatic creatures from the Tingjiang river catchment affected by the mining activities. In this study, we collected grass carps (Ctenopharyngodon idellus) from four sites, and analyzed the accumulation of chromium (Cr), nickel (Ni), manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) in ten tissues (scale, skin, muscle, gill, liver, kidney, fish maw, heart, stomach, and intestine) of the fish samples. Among all tissue samples, the highest concentrations (micrograms per gram wet weight) of Ni (0.263), Cu (69.2), Zn (84.0), As (0.259), Cd (0.640), Hg (0.051), and Pb (0.534) were noted in the liver, gill, and kidney tissues, whereas the highest concentrations of Cr (0.356) and Mn (62.7) were detected in the skin and intestine, respectively. These results gave a better understanding of the variability of metals distribution in different fish tissues. In comparison with the sample sites, metals (especially Mn, Cu, Zn, Ni, and Pb) in liver, gill, kidney, stomach, and intestine showed more inter-site differences than other tissues. The inter-site differences also revealed that site 1 and 2 increased fish uptake of Cu, Zn, Ni, and Pb, which may indicate that the copper mine and urban effluents contributed to high levels of these metals in aquatic environments in site 1 and 2. A potential food safety issue may emerge depending on the mining activities in this region because some metals in a few tissue samples exceeded the guideline values for human consumption of fish.",
Arsenic,735038,"Persistence of DNA damage following exposure of human bladder cells to chronic monomethylarsonous acid Abstract: Malignant transformation was demonstrated in UROtsa cells following 52-weeks of exposure to 50 nM monomethylarsonous acid (MMA(III)); the result was the malignantly transformed cell line, URO-MSC. URO-MSC cells were used to study the induction of DNA damage and the alteration of DNA repair enzymes in both the presence of MMA(III) [URO-MSC(+)] and after subsequent removal of MMA(III) [URO-MSC(-)] following chronic, low-level exposure. In the presence of MMA(III), URO-MSC(+) cells demonstrated a sustained increase in DNA damage following 12-weeks of exposure; in particular, a significant increase in DNA single-strand breaks at 12-weeks of exposure consistently elevated through 52 weeks. The persistence of DNA damage in URO-MSC cells was assessed after a 2-week removal of MMA(III). URO-MSC(-) cells demonstrated a decrease in DNA damage compared to URO-MSC(+); however, DNA damage in URO-MSC(-) remained significantly elevated when compared to untreated UROtsa and increased in a time-dependent manner. Reactive oxygen species (ROS) were demonstrated to be a critical component in the generation of DNA damage determined through the incubation of ROS scavengers with URO-MSC cells. Poly (ADP-ribose) polymerase (PARP) is a key repair enzyme in DNA single-strand break repair. URO-MSC(+) resulted in a slight increase in PARP activity after 36-weeks of MMA(III) exposure, suggesting the presence of MMA(III) is inhibiting the increase in PARP activity. In support, PARP activity in URO-MSC(-) increased significantly, coinciding with a subsequent decrease in DNA damage demonstrated in URO-MSC(-) compared to URO-MSC(+). These data demonstrate that chronic, low-level exposure of UROtsa cells to 50 nM MMA(III) results in: the induction of DNA damage that remains elevated upon removal of MMA(III); increased levels of ROS that play a role in MMA(III) induced-DNA damage; and decreased PARP activity in the presence of MMA(III).",
Arsenic,2088564,"Characterization of Intracellular Inclusions in the Urothelium of Mice Exposed to Inorganic Arsenic Abstract: Inorganic arsenic (iAs) is a known human carcinogen at high exposures, increasing the incidences of urinary bladder, skin and lung cancers. In most mammalian species, ingested iAs is excreted mainly through urine primarily as dimethylarsinic acid (DMA(V)). In wild type (WT) mice, iAs, DMA(V) and dimethylarsinous acid (DMA(III)) (iAs(III)) exposure induces formation of intramitochondrial urothelial inclusions. Arsenite (iAs(III)) also induced intranuclear inclusions in arsenic (+3 oxidation state) methyltransferase knockout (As3mt KO) mice. The arsenic induced formation of inclusions in the mouse urothelium was dose and time dependent. The inclusions do not occur in iAs-treated rats, and do not appear to be related to arsenic-induced urothelial cytotoxicity. Similar inclusions in exfoliated urothelial cells from humans exposed to iAs have been incorrectly identified as micronuclei. We have characterized the urothelial inclusions using transmission electron microscopy (TEM), DNA-specific 4',6-diamidino-2-phenylindole (DAPI) and non-DNA-specific Giemsa staining, and determined the arsenical content. The mouse inclusions stained with Giemsa but not with the DAPI stain. Analysis of urothelial mitochondrial and nuclear enriched fractions isolated from WT (C57BL/6) and As3mt KO mice exposed to iAs(V) for 4 weeks showed higher levels of of iAs(V) in the treated groups. iAs(III) was the major arsenical present in the enriched nuclear fraction from iAs(V)-treated As3mt KO mice. In conclusion, the urothelial cell inclusions induced by arsenicals appears to serve as a detoxifying sequestration mechanism similar to other metals and they do not represent micronuclei.",
Arsenic,1519160,Effectiveness of garlic oil in the treatment of arsenical palmer keratosis Abstract: ,
Arsenic,1349107,Field tests of the efficacy of zinc and fatty amine in preventing colonization by copper-tolerant fungi Abstract: ,
Arsenic,1352358,"Simultaneous multi-channel hydride generation atomic fluorescence spectrometry determination of arsenic, bismuth, tellurium and selenium in tea leaves Abstract: ",
Arsenic,607670,"Arsenic and cigarette smoke synergistically increase DNA oxidation in the lung Abstract: Epidemiological evidence has indicated that arsenic and cigarette smoking exposure act synergistically to increase the incidence oflung cancer. Since oxidative damage of DNA has been linked to cancer, our hypothesis is that aerosolized arsenic and cigarette smoke work synergistically to increase oxidative stress and increase DNA oxidation in the lung. To test this hypothesis male Syrian golden hamsters were exposed to room air (control), aerosolized arsenic compounds (3.2 mg/m3 for 30 minutes), cigarette smoke (5 mg/m3 for 30 minutes), or both smoke and arsenic. Exposures were for 5 days/week for 5 or 28-days. Animals were sacrificed one day after the last exposure. In the 28-day group, glutathione levels and DNA oxidation (8-oxo-2'-deoxyguanosine (8-oxo-dG)) were detel1nined. Our results show that in the 28-day arsenic/smoke group there was a significant decrease in both the reduced and total glutathione levels compared with arsenic or smoke alone. This correlated with a 5-fold increase in DNA oxidation as shown by HPLC. Immunohistochemical localization of 8-oxo-dG showed increase staining in nuclei of airway epithelium and subadjacent interstitial cells. These results show that dual exposure of arsenic and cigarette smoke at environmentally relevant levels can act synergistically to cause DNA damage.",
Arsenic,1677547,"The availability and mobility of arsenic and antimony in an acid sulfate soil pasture system Abstract: The Macleay floodplain on the north coast of New South Wales, Australia, has surface soil concentrations of up to 40mgkg(-1) arsenic (As) and antimony (Sb), due to historical mining practices in the upper catchment. The floodplain also contains areas of active and potential acid sulfate soils (ASS). Some of these areas are purposely re-flooded to halt oxidation processes, but the effect of this management on the metalloid mobility and phytoavailability of the metalloids present is unknown. This study investigated the changes to soil solution As and Sb, associations of metalloids with soil solid phases, and uptake into two common pasture species following 20weeks of flooding in a controlled environment. The effect of an ASS subsoil was also investigated. The soil solution concentration and availability of the metalloids was in some instances higher in the floodplain soils than would generally be expected in soils with comparable contamination. There appeared to be few changes to soil solution concentrations or phase associations with flooding in this short term study, due to the high acid buffering and poise of the investigated soils. A strong relationship was found between the relative uptake of Sb into pastures and the oxalate extractable Fe in the soil, which was taken as a proxy for non-crystalline iron (Fe) hydroxides. This relationship was dependent on flooding and was absent for As. Further targeted investigations into metalloid speciation kinetics and the stability of soil solid phases with flooding management are recommended.",
Arsenic,1130648,"Daily intake of inorganic arsenic and some organic arsenic species of Japanese subjects Abstract: The daily dietary intake of inorganic arsenic (InAs) and some of organic arsenic (OrAs) species of Japanese subjects were estimated by determining the concentrations of As species in two different sets of total diet sample: duplicated diet samples collected from 25 subjects in Japan and a certified reference material with total diet matrix (NIES CRM No. 27 Typical Japanese Diet, TJD). The concentration of InAs and OrAs in diet samples were determined by LC-ICP-MS using a photo-oxidation and hydride generation system. The median intake of InAs for the 25 subjects was 3.8?gday(-1) (2.0-57?gday(-1)) and intake of 27?gday(-1) was estimated from TJD. The median intake of MMA, DMA and TMAsO were &lt;0.18, 1.1 and &lt;0.053?gday(-1) for the 25 subjects and that of MMA, DMA, AB and TMAsO was estimated to be 3.9, 11, 140 and 5.9?gday(-1), respectively, based on TJD analysis. On the basis of InAs intakes estimated and the oral slope factor of the US EPA and Health Canada, excess cancer risk was estimated to exceed acceptable level. Cancer risk posed by the dietary InAs of the general Japanese may not be negligible.",
Arsenic,1373027,"Gene Expression Profiling Of Mouse Skin And Papillomas Following Chronic Exposure To Monomethylarsonous Acid In K6/ODC Transgenic Mice Abstract: Methylarsonous acid [MMA(III)], a common metabolite of inorganic arsenic metabolism, increases tumor frequency in the skin of K6/ODC transgenic mice following a chronic exposure. To characterize gene expression profiles predictive of MMA(III) exposure and mode of action of carcinogenesis, K6/ODC mice were administered 0, 10, 50 or 100 ppm MMA(III) or 75 ppm sodium arsenite in their drinking water for 26 weeks. Skin and tumor gene expression changes were determined using Affymetrix Mouse Genome 430A 2.0 GeneChips? and MAS 5.0 normalization procedures. Differential gene expression was determined using linear regression and a regularized t-test (Bayesian procedure). Functional gene categorization was assessed using the Database for Annotation, Visualization and Integrated Discovery 2.0 (DAVID, Dennis and Hosack et al. 2003). Linear regression analysis revealed changes in multiple cytoskeleton and cell cycle-related genes including enabled homolog (Enah) and the tumor suppressor gene p27 (Cdkn1b). The dose-dependent decrease in p27 mRNA we observed in mouse skin is consistent with the previously reported reduction in p27 protein observed in arsenical-induced urinary bladder lesions. Using a regularized t-test, significant changes were also observed in multiple oncogenes including changes in c-myc (Myc), fra-1(Fosl1), and v-maf (Mafb). Significant increases we observed in c-myc mRNA in mouse skin and papillomas are consistent with increases in c-myc during arsenic-induced mouse liver carcinogenesis. Since c-myc protein can bind the promoter of p27 and regulate its transcription, the molecular changes observed in our study are likely related and also important in MMA(III)-induced mouse skin carcinogenesis. Additional gene expression changes we observed in chromosome maintenance and steroid metabolism genes may also contribute to the carcinogenesis process in mouse skin.",
Arsenic,1519070,"Auxin and its transport play a role in plant tolerance to arsenite induced oxidative stress in Arabidopsis thaliana Abstract: The role of auxin in plant development is well known, however its possible function in root response to abiotic stress is poorly understood. In this study, we demonstrate a novel role of auxin transport in plant tolerance to oxidative stress caused by arsenite. Plant response to arsenite [As(III)] was evaluated by measuring root growth and markers for stress on seedlings treated with control or As(III)-containing medium. Auxin transporter mutants aux1, pin1 and pin2 were significantly more sensitive to As(III) than the wild-type (WT). Auxin transport inhibitors significantly reduced plant tolerance to As(III) in the WT while exogenous supply of indole-3- acetic acid improved As(III) tolerance of aux1 and not that of WT. Uptake assays using H(3) -IAA, showed As(III) affected auxin transport in WT roots. As(III) increased the levels of H2 O2 in WT but not in aux1 suggesting a positive role for auxin transport through AUX1 on plant tolerance to As(III) stress via ROS mediated signaling. Compared to the WT, the mutant aux1 was significantly more sensitive to high temperature stress and salinity also , suggesting auxin transport influences a common element shared by plant tolerance to arsenite, salinity and high temperature stress.",
Arsenic,1579328,"Proteomic analysis of arsenic-exposed zebrafish (Danio rerio) identifies altered expression in proteins involved in fibrosis and lipid uptake in a gender-specific manner Abstract: The zebrafish (Danio rerio) was used to investigate protein expression in the liver following arsenic exposure. Several disorders have been linked to arsenic exposure including cancer, diabetes and cardiovascular disease. The mechanisms of arsenic toxicity, however, are still poorly understood. Prior studies have described altered gene expression, inflammation, and mitogenic signaling in acute or chronic exposure models. A proteomic approach was employed to investigate arsenic-induced alteration in the zebrafish liver proteome following a seven-day exposure to 50 ppb sodium arsenite. Over 740 unique proteins were identified, with fewer than 2% showing differential expression. Molecular pathway analysis software identified lipid metabolism and transport as potential molecular targets. Immunoblots were used to confirm protein expression changes while qPCR was employed to investigate gene expression changes. Overall, 24 proteins were differentially expressed in a gender-specific manner, eleven in males and thirteen in females. Of these 24, a single protein, hydroxysteroid dehydrogenase like 2 (HSDL2), showed decreased expression in both males and females following arsenic exposure. These findings indicate protein expression is altered following arsenic exposure. The changes presented here seem to be most prevalent in lipid transport and metabolic pathways, suggesting a potential increase in fibrosis in males, and decreased lipid accumulation and uptake in females.",
Arsenic,1797742,"Adsorption kinetics and isotherms of arsenic(V) from aqueous solution onto Ni0.5Zn0.5Fe2O4 nanoparticles Abstract: Magnetic Ni0.5Zn0.5Fe2O4 nanoparticles were synthesized by the facile citrate-gel process. Their morphology, chemical composition, microstructure, and magnetic properties were investigated by XRD, TEM, EDX, BET, and VSM. The as-prepared magnetic Ni0.5Zn0.5Fe2O4 nanoparticles consisting of grains about 20 nm were characterized with specific surface area of 49.0 m2/g and magnetization of 46.1 A m2/kg. The arsenic(V) adsorption onto these magnetic Ni0.5Zn0.5Fe2O4 nanoparticles at room temperature was determined by the ICP-AES measurement of arsenic(V) in aqueous solution. The results show that the pseudo-second-order kinetic model is fitted well to describe the arsenic(V) adsorption process with a determination coefficient (R2 = 0.9862). By comparing with the two- and three-parameter models for adsorption isotherms of arsenic(V) onto the magnetic Ni0.5Zn0.5Fe2O4 nanoparticles at room temperature, the Temkin and Redlich-Peterson model can be used to evaluate the arsenic(V) adsorption isotherm at room temperature. The arsenic(V) equilibrium adsorption quantity is up to 7.2 mg/g for these magnetic Ni0.5Zn0.5Fe2O4 nanoparticles when the initial arsenic(V) concentration is 3 mg/L in aqueous solution.",
Arsenic,1030880,"Arsenic in tissues of sheep and milk of dairy cows fed arsanilic acid and 3-nitro-4-hydroxyphenylarsonic acid Abstract: Arsenic from two sources--arsanilic acid and 3-nitro-4-hydroxyphenylarsonic acid (3-nitro)--was fed to mature wethers and lactating dairy cows, and the uptake and depletion of arsenic in tissues and milk were determined. In experiments with sheep, arsenic concentration in liver, kidney and blood increased as the level of arsenic from arsanilic acid and 3-nitro was increased in feed. Muscle arsenic was relatively unaffected by the level of arsenic in feed from either source. No statistically significant differences in arsenic levels were observed between liver and kidney tissue, over all levels fed, or for either source of arsenic. When comparisons were made within each tissue, arsenic levels were found to be significantly lower in sheep fed 3-nitro. This difference between 3-nitro and arsanilic acid within tissues was not observed in muscle or blood. The depletion rates for arsenic were the same for all tissues, and the time required for tissue to return to pretreatment arsenic levels was dependent on the initial tissue concentration. Within 6 days of removal of arsenic from the sheep diets, 85% of the arsenic in the liver of sheep fed arsanilic acid and 81% of the arsenic in the liver of sheep fed 3-nitro was depleted. Arsenic levels in the kidneys of sheep fed arsanilic acid and 3-nitro were depleted by 87 and 83%, respectively. In the experiments with lactating dairy cows, significantly higher levels of arsenic in milk were observed for cows fed either 3.2 or 4.8 mg of arsenic per kilogram of body weight from arsanilic acid or 3-nitro. In the experiment in which 3-nitro was fed at a level of 4.8 mg/kg of body weight for 28 days, arsenic levels plateaued after 14 days of feeding and remained constant for the next 14 days. Milk arsenic from 3-nitro returned to pre-experiment levels within 5 days after arsenic was removed from the feed. In the experiment conducted with arsanilic acid, arsenic feeding was stopped after 5 days and milk arsenic levels returned to pre-experiment levels within 7 days. Because of the short duration of this study, no plateauing effect was observed.",
Arsenic,1034266,"Specific inhibition of myelination by lead in vitro; comparison with arsenic, thallium, and mercury Abstract: Lead induces peripheral nerve segmental demyelination in rats. Arsenic and thallium produce a peripheral neuropathy characterized by axonal degeneration in humans. Mercury and thallium appear to damage both the peripheral and the central nervous system. It is not known whether this difference in effect is due to different molecular forms of the elements, to differential access to various compartments of the nervous system, or to intrinsically different properties of the elements. Using an in vitro model system of dorsal root ganglion neurons and morphometry of neurite outgrowth and myelination, we demonstrated that mercury and arsenic produce 50% inhibition of neurite outgrowth at 3.9 and 9.6 X 10(-6) M, respectively, whereas the same degree of inhibition is produced by 1.3 X 10(-4) M thallium and 3.3 X 10(-4) M lead. Lead also produces complete inhibition of myelination at 1 X 10(-6) M, suggesting that a primary effect on myelination is present in this model system as well as in the intact rodent.",
Arsenic,2345784,"Toxicity of arsenic in relation to soil properties: implications to regulatory purposes Abstract: Purpose The present work evaluates the influence of different soil properties and constituents on As solubility in laboratory-contaminated soils, with the aim of assessing the toxicity of this element from the use of bioassays to evaluate the soil leachate toxicity and thereby propose soil guideline values for studies of environmental risk assessment in soil contamination. <br> <br>Materials and methods Seven soils with contrasting properties were artificially contaminated in laboratory with increasing concentrations of As. Samples were incubated for 4 weeks, and afterwards, soil solution (1:1) was obtained after shaking for 24 h. The soil leachate toxicity was assessed with two commonly used bioassays (seed germination test with Lactuca sativa and Microtox (R) test with Vibrio fischeri). <br> <br>Results and discussion The relationship between soluble As and soil properties indicated that iron oxides and organic matter content were the variables most closely related to the reduction of the As solubility, while pH and CaCO3 increased As solubility in the soil solutions. Toxicity bioassays showed significant differences between soils depending on their properties, with a reduction of the toxicity in the iron-rich soil (no observed effect concentration (NOEC)=150 mg kg(-1)) and a significant increase in the highly carbonate samples (NOEC between 15 and 25 mg kg(-1)). <br> <br>Conclusions Soil guideline values for regulatory purposes usually set a single value for large areas (regions or countries) which can produce over-or underestimation of efforts in soil remediation actions. These values should consider different levels according to the main soil properties controlling arsenic mobility and the soil leachate toxicity.",
Arsenic,2279407,"Spatial clustering of toxic trace elements in adolescents around the Torreón, Mexico lead-zinc smelter Abstract: High blood lead (BPb) levels in children and elevated soil and dust arsenic, cadmium, and lead were previously found in Torreón, northern Mexico, host to the world's fourth largest lead-zinc metal smelter. The objectives of this study were to determine spatial distributions of adolescents with higher BPb and creatinine-corrected urine total arsenic, cadmium, molybdenum, thallium, and uranium around the smelter. Cross-sectional study of 512 male and female subjects 12-15 years of age was conducted. We measured BPb by graphite furnace atomic absorption spectrometry and urine trace elements by inductively coupled plasma-mass spectrometry, with dynamic reaction cell mode for arsenic. We constructed multiple regression models including sociodemographic variables and adjusted for subject residence spatial correlation with spatial lag or error terms. We applied local indicators of spatial association statistics to model residuals to identify hot spots of significant spatial clusters of subjects with higher trace elements. We found spatial clusters of subjects with elevated BPb (range 3.6-14.7??g/dl) and urine cadmium (0.18-1.14??g/g creatinine) adjacent to and downwind of the smelter and elevated urine thallium (0.28-0.93??g/g creatinine) and uranium (0.07-0.13??g/g creatinine) near ore transport routes, former waste, and industrial discharge sites. The conclusion derived from this study was that spatial clustering of adolescents with high BPb and urine cadmium adjacent to and downwind of the smelter and residual waste pile, areas identified over a decade ago with high lead and cadmium in soil and dust, suggests that past and/or present plant operations continue to present health risks to children in those neighborhoods.",
Arsenic,1704125,Formation process of pyrite polyframboid based on the heavy-metal analysis by micro-PIXE Abstract: ,
Arsenic,2347578,"Differences of urinary arsenic metabolites and methylation capacity between individuals with and without skin Lesions in Inner Mongolia, Northern China Abstract: Incomplete arsenic (As) methylation has been considered a risk factor of As-related diseases. This study aimed to examine the difference of urinary As metabolites and the methylation capacity between subjects with and without skin lesions. Urinary inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were analyzed. The percentage of each As species (iAs%, MMA%, and DMA%), the primary methylation index (PMI) and secondary methylation index (SMI) were calculated. The results showed that subjects with skin lesions have higher levels of urinary iAs (99.08 vs. 70.63 ?g/g Cr, p = 0.006) and MMA (69.34 vs. 42.85 ?g/g Cr, p = 0.016) than subjects without skin lesions after adjustment for several confounders. Significant differences of urianry MMA% (15.49 vs. 12.11, p = 0.036) and SMI (0.74 vs. 0.81, p = 0.025) were found between the two groups. The findings of the present study suggest that subjects with skin lesions may have a lower As methylation capacity than subjects without skin lesions.",
Arsenic,2279027,"Biogenic catalysis in sulphide minerals' weathering processes and acid mine drainage genesis Abstract: Bioleaching and biogenesis are the main outputs from a large group of environmental processes participating in the natural material cycle, used in raw materials processing. Bio-oxidation reactions are the main basis for bioleaching procedures, often participating in parallel leaching processes. During the leaching processes of polycomponent sulphide substrates, the factor of process selection also plays an important role, being in direct relation to the electric properties and galvanic effect occurring between the individual components of the leaching substrate. This work gives a summary of the results of a research focused on the possibilities of using biotechnological procedures for treatment of Slovak sulphide ores. The object of the research is extraction of valuable metals, undesirable admixtures and degradation of crystal lattice of sulphides for subsequent chemical leaching processing of precious metals. The results of experiments on the existence of biogenic processes in situ on waste dumps from exploitation containing residual sulphides are also presented. The processes result in acid mine drainage water generation. These waters are strongly mineralised (over 48 g/L) and of low pH; that is why they are very caustic. The arsenic content (2.558 mg/L) in outflowing waters from old mines is high and over the limits set by the law.",
Arsenic,1354150,"SCRAPIE PRIONS SELECTIVELY MODIFY THE STRESS-RESPONSE IN NEUROBLASTOMA-CELLS Abstract: The fundamental event underlying scrapie infection seems to be a conformational change in the prion protein. To investigate proteins that might feature in the conversion of the cellular prion protein (PrPC) into the scrapie isoform (PrPSc), we examined mouse neuroblastoma N2a cells for the expression and cellular distribution of heat shock proteins (Hsps), some of which function as molecular chaperones. In scrapie-infected N2a (ScN2a) cells, Hsp72 and Hsp28 were not induced by heat shock, sodium arsenite, or an amino acid analog, in contrast to uninfected control N2a cells, while other inducible Hsps were increased by these treatments. Following heat shock of the N2a cells, constitutively expressed Hsp73 was translocated from the cytoplasm into the nucleus and nucleolus. In contrast, the distribution of Hsp73 in ScN2a cells was not altered by heat shock; the discrete cytoplasmic structures containing Hsp73 were largely resistant to detergent extraction. These alterations in the expression and subcellular translocation of specific Hsps in ScN2a cells may reflect the cellular response to the accumulation of PrPSc. Whether any of these Hsps feature in the conversion of PrPC into PrPSc or the pathogenesis of prion diseases remains to be established.",
Arsenic,1339831,"mTOR is essential for the proteotoxic stress response, HSF1 activation and heat shock protein synthesis Abstract: The target of rapamycin (TOR) is a high molecular weight protein kinase that regulates many processes in cells in response to mitogens and variations in nutrient availability. Here we have shown that mTOR in human tissue culture cells plays a key role in responses to proteotoxic stress and that reduction in mTOR levels by RNA interference leads to increase sensitivity to heat shock. This effect was accompanied by a drastic reduction in ability to synthesize heat shock proteins (HSP), including Hsp70, Hsp90 and Hsp110. As HSP transcription is regulated by heat shock transcription factor 1 (HSF1), we examined whether mTOR could directly phosphorylate this factor. Indeed, we determined that mTOR could directly phosphorylate HSF1 on serine 326, a key residue in transcriptional activation. HSF1 was phosphorylated on S326 immediately after heat shock and was triggered by other cell stressors including proteasome inhibitors and sodium arsenite. Null mutation of S326 to alanine led to loss of ability to activate an HSF1-regulated promoter-reporter construct, indicating a direct role for mTOR and S326 in transcriptional regulation of HSP genes during stress. As mTOR is known to exist in at least two intracellular complexes, mTORC1 and mTOR2 we examined which complex might interact with HSF1. Indeed mTORC1 inhibitor rapamycin prevented HSF1-S326 phosphorylation, suggesting that this complex is involved in HSF1 regulation in stress. Our experiments therefore suggest a key role for mTORC1 in transcriptional responses to proteotoxic stress.",
Arsenic,1340284,"A comparative study of stress-mediated immunological functions with the adjuvanticity of alum Abstract: The efficacy of a vaccine is generally dependent on an adjuvant, which enhances the immune functions and alum has been widely used in human immunization. Alum activates the intracellular stress sensors inflammasomes, but whether these are responsible for the adjuvanticity is controversial. The objectives of this investigation were to examine the hypothesis that alum-mediated adjuvanticity is a function of stress and conversely that stress agents will elicit adjuvanticity. The investigation was carried out in BALB/c mice by SC immunization with ovalbumin (OVA) mixed with alum. This elicited inflammasomes, with significant activation of caspase 1, production of IL-1?, and adjuvanticity, demonstrated by enhancing OVA-specific serum IgG antibodies, CD4(+) T cells, and proliferation. The novel finding that alum induced HSP70 suggests that stress is involved in the mechanism of adjuvanticity. This was confirmed by inhibition studies with PES (phenylethynesulfonamide), which disrupts inducible HSP70 function, and inhibited both inflammasomes and the adjuvant function. Parallel studies were pursued with an oxidative agent (sodium arsenite), K-releasing agent (Gramicidin) and a metal ionophore (dithiocarbamate). All 3 stress agents induced HSP70, inflammasomes, and the adjuvant functions. Furthermore, up-regulation of membrane associated IL-15 on DC and CD40L on T cells in the animals treated with alum or the stress agents mediate the interactions between splenic CD11c DC and CD4(+) or CD8(+) T cells. The results suggest that the three stress agents elicit HSP70, a hallmark of stress, as well as inflammasomes and adjuvanticity, commensurate with those of alum, which may provide an alternative strategy in developing novel adjuvants.",
Arsenic,471144,"Co-exposure to arsenic and fluoride on oxidative stress, glutathione linked enzymes, biogenic amines and DNA damage in mouse brain Abstract: We studied the effects of combined exposure to arsenic and fluoride on (i) brain biogenic amines, oxidative stress and its correlation with glutathione and linked enzymes; (ii) alterations in the structural integrity of DNA; and (iii) brain and blood arsenic and fluoride levels. Efficacy of alpha-tocopherol in reducing these changes was also determined. Male mice were exposed to sodium meta arsenite (50 ppm) and sodium fluoride (50 ppm) individually and in combination for ten weeks. Animals were given vitamin E supplementation (5 mg/kg, i.m., alternate days) throughout the experiment. Exposure to arsenic and fluoride significantly decreased the levels of brain biogenic amines. However; acetyl cholinesterase (AChE) and monoamine oxidase (MAO) activities showed an increase on fluoride exposure. There was also an increase in reactive oxygen species, thiobarbituric acid reactive species level, glutathione S-transferase and glutathione peroxidase activities and decreased superoxide dismutase activity, GSH:GSSG ratio, glucose 6-phosphate dehydrogenase activity. Combined exposure to these toxicants produced more pronounced effects on AChE, MAO, SOD and catalase activities. Infrared spectra showed less toxicity during combined exposure as the characteristic peaks of cytosine and alpha-helical structure of DNA were observed in normal and arsenic plus fluoride-exposed animals. Vitamin E reduced brain fluoride level and tissue oxidative stress but had no effect on arsenic. Combined exposure to arsenic and fluoride does not necessarily lead to more pronounced toxicity and interestingly exhibit some antagonistic effects. Vitamin E supplementation may be of added value in reverting some of the toxic effects. (c) 2009 Elsevier B.V. All rights reserved.",
Arsenic,2279157,"Methylation marker analysis of self-sampled cervico-vaginal lavage specimens to triage high-risk HPV-positive women for colposcopy Abstract: Methylation markers were studied for their suitability to triage human papillomavirus (HPV)-positive women by testing self-collected cervico-vaginal lavage specimens. For this purpose, we analyzed 355 hrHPV-positive self-collected specimens with three methylation markers, that is, CADM1-m18, MAL-m1 and miR-124-2 by quantitative methylation-specific PCR. The areas under the receiver-operating characteristic (ROC) curve for end-point cervical intraepithelial neoplasia grade 3 or worse (CIN3+) were 0.637 for CADM1-m18, 0.767 for MAL-m1 and 0.762 for miR-124-2. This indicates that CADM1-m18 is not suitable as single marker. By varying the thresholds of both markers in the bi-marker panels CADM1-m18/MAL-m1, CADM1-m18/miR-124-2 and MAL-m1/miR-124-2 upper and lower ROC curves were obtained, depicting the maximum and minimum CIN3+ sensitivity, respectively, at given specificity. For all these bi-marker combinations, the upper curves were similar. However, for the MAL-m1/miR-124-2 panel, the distance between upper and lower ROC curves was closest and this panel displayed the highest assay thresholds, indicating that this combination was most robust. At clinical specificities of 50 and 70%, the MAL-m1/miR-124-2 sensitivity for detection of CIN3+ ranged from 77.0 to 87.8% and from 64.9 to 71.6%, respectively. At 70% specificity thresholds no carcinomas were missed. By comparison, the CIN3+ sensitivity of HPV16/18 genotyping on the self-sampled lavage specimens was 58.1% (95%CI: 46.6-68.8) at a specificity of 87.7% (95%CI: 83.2-91.2). In conclusion, methylation analysis is a promising triage tool that in combination with HPV-DNA testing offers feasible, full molecular screening on self-collected cervico-vaginal lavage specimens.",
Arsenic,1579367,"Sugarcane bagasse treated with hydrous ferric oxide as a potential adsorbent for the removal of As(V) from aqueous solutions Abstract: The mechanism of As(V) removal from aqueous solutions by means of hydrated ferric oxide (HFO)-treated sugarcane bagasse (SCB-HFO) (Saccharum officinarum L.) was investigated. Effects of different parameters, such as pH value, initial arsenic concentration, adsorbent dosage, contact time and ionic strength, on the As(V) adsorption were studied. The adsorption capacity of SCB-HFO for As(V) was found to be 22.1 mg/g under optimum conditions of pH 4, contact time 3h and temperature 22 °C. Initial As(V) concentration influenced the removal efficiency of SCB-HFO. The desorption of As(V) from the adsorbent was 17% when using 30% HCl and 85% with 1M NaOH solution. FTIR analyses evidenced two potential binding sites associated with carboxyl and hydroxyl groups which are responsible for As(V) removal. Adsorption, surface precipitation, ion exchange and complexation can be suggested as mechanisms for the As(V) removal from the solution phase onto the surface of SCB-HFO.",
Arsenic,2298745,"Trace metal concentrations measured in blood and urine of adolescents in Flanders, Belgium: Reference population and case studies Genk-Zuid and Menen Abstract: In the Flemish human biomonitoring programme FLEHS II (2007-2011) trace metals (Cd, Pb, Cr, Ni, Cu, Mn, Tl, Sb, As and toxic relevant arsenic) were analysed in the blood and urine of adolescents (14-15 years old) in the reference population in Flanders and in areas of important industrial activities: Genk-Zuid and Menen. After adjustment of the results for confounding factors, the adolescents living in Genk-Zuid had higher levels of Cr, Cu and Tl in blood, higher levels of Cd and toxic relevant arsenic (TRA) in urine, but lower levels of Ni in blood and Sb in urine compared to the reference population. In Menen higher levels of Cd and Cu in urine, higher concentrations of Tl in blood but lower concentrations of Pb in blood and lower Ni, Sb and As in urine were found compared to the reference population. For both the reference population and the hot spots the concentrations are within the ranges found in other countries. Compared to the previous biomonitoring programme FLEHS I (2002-2006) a decrease in the concentrations of Cd and especially of Pb in blood was observed. However, it cannot be excluded that differences between the two campaigns are partially due to different sampling strategies.",
Arsenic,1015776,"Soil contamination of metals in the three industrial estates, arak, iran Abstract: The aim of this study was to determine the concentrations and degree of metals contamination (Chromium, Cadmium, Nickel and Lead) and Arsenic in the soils of the three Industrial Estates in Arak city, Iran. The average concentrations of Arsenic, Chromium, Cadmium, Nickel and Lead were 5.06, 1.26, 37.13, 67.84 and 60.22 mg kg(-1), respectively. Pearson correlation indicated that Arsenic, Cadmium and Lead were mainly derived from anthropogenic inputs, and Chromium and Nickel were controlled by natural source, whereas Nickel appeared to be affected by both anthropogenic and natural sources. The geo-accumulation Index (Igeo) calculated in three industrial estates gave values indicating unpolluted to strongly polluted.",
Arsenic,1519203,"Comprehensive analysis of heavy metals in soils from Baoshan District, Shanghai: A heavily industrialized area in China Abstract: The potential for soil heavy metal contamination in high risk areas is a crucial issue that will impact the environment. Soil samples were collected in 2003 and 2007 to investigate heavy metal contamination characteristics and pollution changes in the industrialized district of Baoshan (Shanghai, China). Both multi-statistic and geostatistic approaches were used and proved to be useful in the interpretation of the analytical results. The potential for soil contamination in the high risk areas presents a crucial issue that will impact the environment. The results indicate that soil in the Baoshan District is alkaline. Additionally, the accumulation of heavy metals in the soil increased between 2003 and 2007. The study results indicated that the concentration of the metals lead (Pb), chromium (Cr), cadmium (Cd), mercury (Hg), arsenic (As), zinc (Zn) and copper (Cu) in the soil has great discrepancy, especially of Pb and Cr. The concentrations of Pb and Cr in the soil show significant difference between two observed years (p < 0.05). The concentration of most of these metals was higher in 2007 than 2003. Only the concentrations of Cd and As were not higher in 2007. Traffic and industrial contaminants were the likely source of Pb and As; Hg largely came from agricultural contamination, household garbage and industrial contamination; Cd, Cr, Zn and Cu mainly originated from industrial activities. Multivariate statistical analyses showed that human activities mainly contributed to heavy metal contamination. Spatial distribution confirmed this by showing that areas with the highest metal concentrations occurred where there were high levels of industrial activity and traffic. Potential ecological risk assessment results showed that high risk zones were highly correlated with spatial analysis. The study estimated that in 2007, 85.2 % of the district could be categorized as high risk, which is 77.4 times more than that in 2003.",
Arsenic,1347902,"Prostaglandins stimulate the stress-induced synthesis of hsp27 and alpha B crystallin Abstract: The effects were examined of various prostaglandins (prostaglandin A1, A2, J2, E2, and D2) on the stress-induced accumulation of hsp27 and alpha B crystallin in C6 rat glioma cells. The levels of hsp27 and alpha B crystallin, which were determined by specific immunoassays, were low in cells in confluent cultures. The levels of the two proteins increased after exposure of cells to heat (42 degrees C for 30 min) or arsenite (50 microM for 1 h). Cells exposed to 10 microM each of prostaglandin A1, A2, or J2 for 1 h resulted in stimulation of the binding to the heat shock element (HSE) of heat shock transcription factor (HSF). However, there was no phosphorylation-dependent mobility shift of HSF1 and no subsequent increase in the transcription and translation for hsp27, alpha B crystallin, and hsp70. When cells were exposed to arsenite in the presence of 10-40 microM prostaglandin, the accumulation of hsp27 and alpha B crystallin in cells was enhanced markedly. The levels of hsp70 also increased in cells that had been treated with arsenite in the presence of a prostaglandin, as estimated by Western blot analysis. Northern blot analysis revealed that the expression of messenger RNAs (mRNAs) for hsp27, alpha B crystallin, and hsp70 was enhanced in cells that had been exposed to arsenite in the presence of each prostaglandin. Similar stimulatory effects of prostaglandins also were observed in the case of the heat-induced responses of hsp27, alpha B crystallin, and hsp70. Gel mobility shift assays revealed that each prostaglandin prolonged the arsenite-induced binding of HSF to HSE. These results suggest that the pharmacological dose of prostaglandins stimulates the stress-induced synthesis of stress proteins via activation of the HSF.",
Arsenic,1199037,CARBON-ENHANCED INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION OF ARSENIC AND SELENIUM AND ITS APPLICATION TO ARSENIC SPECIATION Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE SHRIMP FOOD ANALYSIS ANALYTICAL METHOD,
Arsenic,1337328,"Risk of arsenic exposure from drinking water and dietary components: Implications for risk management in rural Bengal Abstract: This study investigates the risk of arsenic (As) exposure to the communities in rural Bengal, even when they have been supplied with As safe drinking water. The estimates of exposure via dietary and drinking water routes show that when people are consuming water with As concentration &lt;10 µg L-1, the total daily intake of inorganic As (TDI-iAs) exceeds the previous provisional tolerable daily intake (PTDI) value of 2.1 µg day-1 kg-1 BW, recommended by World Health Organization (WHO) in 35% of the cases due to consumption of rice. When the level of As concentration in drinking water is above 10 µg L-1, the TDI-iAs exceeds the previous PTDI for all the participants. These results imply that when rice consumption is a significant contributor to the TDI-iAs, supplying water with As concentration at current national drinking water standard for India and Bangladesh would place many people above the safety threshold of PTDI. We also found that the consumption of vegetables in rural Bengal does not pose significant health threat to the population independently. This study suggests that any effort to mitigate the As exposure of the villagers in Bengal must consider the risk of As exposure from rice consumption together with drinking water.",
Arsenic,1508600,"Arsenic induced neuronal apoptosis in guinea pigs is Ca2+ dependent and abrogated by chelation therapy: Role of voltage gated calcium channels Abstract: Arsenic contaminated drinking water has affected more than 200 million people globally. Chronic arsenicism has also been associated with numerous neurological diseases. One of the prime mechanisms postulated for arsenic toxicity is reactive oxygen species (ROS) mediated oxidative stress. In this study, we explored the kinetic relationship of ROS with calcium and attempted to dissect the calcium ion channels responsible for calcium imbalance after arsenic exposure. We also explored if mono- or combinational chelation therapy prevents arsenic-induced (25ppm in drinking water for 4 months) neuronal apoptosis in a guinea pig animal model. Results indicate that chronic arsenic exposure caused a significant increase in ROS followed by NO and calcium influx. This calcium influx is mainly dependent on L-type voltage gated channels that disrupt mitochondrial membrane potential, increase bax/bcl2 levels and caspase 3 activity leading to apoptosis. Interestingly, blocking of ROS could completely reduce calcium influx whereas calcium blockage partially reduced ROS increase. While in general mono- and combinational chelation therapies were effective in reversing arsenic induced alteration, combinational therapy of DMSA and MiADMSA was most effective. Our results provide evidence for the role of L-type calcium channels in regulating arsenic-induced calcium influx and DMSA+MiADMSA combinational therapy may be a better protocol than monotherapy in mitigating chronic arsenicosis.",
Arsenic,1015721,"Arsenic uptake and speciation and the effects of phosphate nutrition in hydroponically grown kikuyu grass (Pennisetum clandestinum Hochst) Abstract: BACKGROUND: This work focuses on the accumulation and mobility properties of arsenic (As) and the effects of phosphate (P) on its movement in Pennisetum clandestinum Hochst (kikuyu grass), grown hydroponically under increasing arsenate (As(V)) concentrations. The uptake of both ions and the relative kinetics show that phosphate is an efficient competitive inhibitor of As(V) uptake. The P/As uptake rate ratios in roots indicate that P is taken up preferentially by P/As transporters. An arsenite (As(III)) efflux from roots was also found, but this decreased when the arsenate concentration in the solution exceeded 5 ?M. METHODS: Increases in both arsenite and arsenate concentrations in roots were observed when the arsenate concentration in the solution was increased, and the highest accumulation of As(III) in roots was found when plants were grown at 5 ?M As(V). The low ratios of As accumulated in shoots compared to roots suggest limited mobility of the metalloid within Kikuyu plants. RESULTS: The results indicate that arsenic resistance in kikuyu grass in conditions of moderate exposure is mainly dependent on the following factors: 1) phosphate nutrition: P is an efficient competitive inhibitor of As(V) uptake because of the higher selectivity of membrane transporters with respect to phosphate rather than arsenate; and 2) a detoxification mechanism including a reduction in both arsenate and arsenite root efflux. CONCLUSIONS: The As tolerance strategy of Kikuyu limits arsenate uptake and As translocation from roots to shoots; therefore, this plant cannot be considered a viable candidate for use in the phytoextraction of arsenic from contaminated soils or water.",
Arsenic,1252273,"Determination of arsenic in orange juice by dry ashing hydride generation atomic-absorption Abstract: A procedure suitable for routine analysis of arsenic in orange juice using instrumentation available in most control laboratories was developed. Organic matter is destroyed by the dry ashing technique, the ash is dissolved in HCl, and hydrides of arsenic are generated by the addition of sodium borohydride prior to atomization in a flame-heated quartz cell and atomic absorption spectroscopy measurement. Experimental conditions for the destruction of organic matter were established, and an interference study was carried out. Copper and iron do not interfere in arsenic determination at levels found in orange juice. The methodology developed has a detection limit in orange juice of 0.1 ng g?1, a relative standard deviation of 1%, and a recovery percentage of 98 ± 8. The accuracy of the proposed method was checked by analysis of a certified sample of tomato leaves, NIST SRM 1573 (certified 0.27 ± 0.05 ?g/g; found 0.26 ± 0.03 ?g/g). The arsenic content of orange juice products was determined. The extremely low arsenic levels found (0.3-4.4 ng g?1)do not present problems from a toxicological point of view.",
Arsenic,1337700,"Arsenic reduction in drinking water and improvement in skin lesions: A follow-up study in Bangladesh Abstract: Background: Chronic exposure to arsenic is associated with skin lesions. However, it is not known whether reducing arsenic exposure will improve skin lesions.Objective: We evaluated the association between reduced arsenic exposures and skin lesion recovery over time.Methods: A follow-up study of 550 individuals was conducted in 2009-2011 on a baseline population of skin lesion cases (n = 900) previously enrolled in Bangladesh in 2001-2003. Arsenic in drinking water and toenails, and skin lesion status and severity were ascertained at baseline and follow-up. We used logistic regression and generalized estimating equation (GEE) models to evaluate the association between log10-transformed arsenic exposure and skin lesion persistence and severity.Results: During the study period, water arsenic concentrations decreased in this population by 41% overall, and 65 individuals who had skin lesions at baseline had no identifiable lesions at follow-up. In the adjusted models, every log10 decrease in water arsenic and toenail arsenic was associated with 22% [odds ratio (OR) = 1.22; 95% CI: 0.85, 1.78] and 4.5 times (OR = 4.49; 95% CI: 1.94, 11.1) relative increase in skin lesion recovery, respectively. In addition, lower baseline arsenic levels were significantly associated with increased odds of recovery. A log10 decrease in toenail arsenic from baseline to follow-up was also significantly associated with reduced skin lesion severity in cases over time (mean score change of -5.22 units; 95% CI: -8.61, -1.82).Conclusions: Reducing arsenic exposure increased the odds that an individual with skin lesions would recover or show less severe lesions within 10 years. Reducing arsenic exposure must remain a public health priority in Bangladesh and in other regions affected by arsenic-contaminated water.",
Arsenic,1339354,"Autophagy is a cell self-protective mechanism against arsenic-induced cell transformation Abstract: Subchronic exposure to arsenic increases the incidence of human cancers such as skin, lung, colon, and rectal cancer. The mechanism for arsenic-induced tumorigenesis is still not clear. It is generally believed that DNA damage and genomic instability, generated by arsenic-promoted oxidative stress, account largely for this process. The major sources of reactive oxygen species (ROS) are arsenic-damaged mitochondria. Autophagy is a catabolic process functioning in turnover of long-lived proteins and dysfunctional organelles such as mitochondria. Defects of autophagy under stress conditions promote genomic instability and increase the risk of tumorigenesis. In the present study using a human bronchial epithelial cell line, BEAS-2B cells, we investigated the role of autophagy in arsenic-induced cell transformation, an important step in arsenic tumorigenesis. Our results show that subchronic arsenic exposure induces BEAS-2B cell transformation accompanied with increased ROS generation and autophagy activation. However, the patterns for ROS and autophagy alteration are different. Arsenic exposure generated a prolonged and steady increase of ROS levels, whereas the activation of autophagy, after an initial boost by arsenic administration, decreases in response to subchronic arsenic exposure, although the activity is still higher than a nontreated control. Further stimulation of autophagy increases mitochondria turnover and decreases ROS generation and arsenic-induced cell transformation. Contrarily, inhibition of autophagy activity decreases mitochondria turnover and enhances arsenic-induced ROS generation and cell transformation. In addition, the mammalian target of rapamycin signaling pathway is involved in arsenic-mediated autophagy activation. Our results suggest that autophagy is a cell self-protective mechanism against arsenic-induced cell transformation.",
Arsenic,1797757,"Evaluation of the application of dry covers over carbonate-rich sulphide tailings Abstract: In this study, four ten years test areas with covered tailings were geochemically evaluated. Three areas were covered with a fly ash and an overlying sludge layer, and one only with a sludge cover, originating from paper mills. The accumulation of As, Fe and Pb in sludge layers, originating from air-borne dust and the depletion of K, Na and P from both cover layers were observed. High release of elements from tailings was observed in the comparison profile due to oxidation and weathering of tailings. In only sludge covered area, the leaching of elements from tailings decreased. In the profiles with thin ash (20 cm and 30 cm), most elements were retained in tailings with pH 7-9. In the profile with the thickest ash (50 cm), elements such as As, Cd, Cu, Mg, Mn, Pb, S and Zn were depleted in the uppermost tailings with pH above 11 and retained deeper in the zone with pH 7-8, which implied that large quantities of fly ash increased the oxidation and weathering of tailings and mobility of elements. Elements excluding K, never reached the groundwater in high concentrations in the covered areas, while the comparison area had high Ca, K, Mn and S concentrations.",
Arsenic,628327,"Effects of low concentrations of arsenic on the innate immune system of the zebrafish (Danio rerio) Abstract: Arsenic has been associated with a multitude of human health problems; however, its impact on host resistance to infection has not been extensively researched. In vertebrates, the innate immune response is vital for potentiating the adaptive immune response. Therefore, dampening of the innate immune response results in an immunocompromised host. In this present study, effects of low concentrations of arsenic on zebrafish resistance to infection are evaluated. Exposure to 2 and 10 ppb arsenic, both considered safe levels in drinking water, resulted in a greater than 50-fold increase in viral load and at least a 17-fold increase in bacterial load in embryos. To determine the cause of this amplified pathogen load, important components of the innate immune system were analyzed. Presence of arsenic dampened the overall innate immune health of the fish as evidenced by reductions in respiratory burst activity. Viral infection, after arsenic exposure, showed decreases of up to 13- and 1.5-fold changes in interferon and Mx mRNA expression, respectively. Bacterial infection, post arsenic exposure, demonstrated at least 2.5- and 4-fold declines in interleukin-1beta and tumor necrosis factor-alpha mRNA levels, respectively. Maximum expression of these essential cytokines was also delayed upon arsenic exposure. Our data indicate that arsenic exposure, at concentrations deemed safe in drinking water, suppresses the overall innate immune function in zebrafish and present the zebrafish as a unique model for studying immunotoxicity of environmental toxicants. To our knowledge, this is the first report describing the effects of such low levels of arsenic on host resistance to infection.",
Arsenic,1350931,"Optimisation of digestion method for determination of arsenic in shrimp paste sample using atomic absorption spectrometry Abstract: The microwave digestion method was developed and verified for the determination of arsenic in shrimp paste samples. Experimental design for five factors (HNO(3) and H(2)O(2) volumes, sample weight, microwave power and digestion time) were used for the optimisation of sample digestion. For this purpose, two level half factorial design, which involves 16 experiments, was adopted. The concentration of arsenic was analysed by graphite furnace atomic absorption spectrometry. Design Expert® 7.0 software was used to interpret all data obtained. The combination of 2mL HNO(3) and 1mL H(2)O(2) volumes, 0.1g sample weight, 1400W power and 5min digestion time was found to be the optimum parameters required to digest the shrimp paste samples. Tests with spiked samples presented good recoveries with relative standard deviations between 0.32% and 5.35%.",
Arsenic,2149352,Arsenic distribution in surface and groundwater in the central bolivian highland Abstract: ,
Arsenic,2347644,"Arsenite Oxidation by the Phyllosphere Bacterial Community Associated with Wolffia australiana Abstract: Speciation is a key determinant in the toxicity, behavior and fate of arsenic (As) in the environment. However, little is known about the transformation of As species mediated by floating macrophytes and the phyllosphere bacteria in aquatic and wetland environment. In this study, Wolffia australiana, a rootless floating duckweed, was cultured with (W+B) or without (W-B) phyllosphere bacteria to investigate its abilities in arsenite (As(III)) oxidation. Results showed that sterile W. australiana did not oxidize As(III) in the growth medium or in plant tissue, whereas W. australiana with phyllpsphere bacteria displayed substantial As(III) oxidation in the medium. Quantitative PCR of As redox-related functional genes revealed the dominance of arsenite oxidase (aioA) gene in the phyllosphere bacterial community. These results demonstrate that the phyllosphere bacteria were responsible for the As(III) oxidation in the W+B system. The rapid oxidation of As(III) by the phyllosphere bacterial community may suppress As accumulation in plant tissues under phosphate rich conditions. The aioA gene library showed that the majority of the phyllosphere arsenite-oxidizing bacteria related either closely to unidentified bacteria found in paddy environments or distantly to known arsenite-oxidizing bacteria. Our research suggests a previously overlooked diversity of arsenite-oxidizing bacteria in the phyllosphere of aquatic macrophytes which may have a substantial impact on As biogeochemistry in water environments, warranting further exploration.",
Arsenic,2278439,"Natural product based leads to fight against leishmaniasis Abstract: The growing incidence of parasitic resistance against generic pentavalent antimonials, specifically for visceral disease in Indian subcontinent, is a serious issue in Leishmania control. Notwithstanding the two treatment alternatives, that is amphotericin B and miltefosine are being effectively used but their high cost and therapeutic complications limit their use in endemic areas. In the absence of a vaccine candidate, identification, and characterization of novel drugs and targets is a major requirement of leishmanial research. This review describes current drug regimens, putative drug targets, numerous natural products that have shown promising antileishmanial activity alongwith some key issues and strategies for future research to control leishmaniasis worldwide.",
Arsenic,2278561,"Multiple cysteine residues are necessary for sorting and transport activity of the arsenite permease Acr3p from Saccharomyces cerevisiae Abstract: The yeast transporter Acr3p is a low affinity As(III)/H(+) and Sb(III)/H(+) antiporter located in the plasma membrane. It has been shown for bacterial Acr3 proteins that just a single cysteine residue, which is located in the middle of the fourth transmembrane region and conserved in all members of the Acr3 family, is essential for As(III) transport activity. Here, we report a systematic mutational analysis of all nine cysteine residues present in the Saccharomyces cerevisiae Acr3p. We found that mutagenesis of highly conserved Cys151 resulted in a complete loss of metalloid transport function. In addition, lack of Cys90 and Cys169, which are conserved in eukaryotic members of Acr3 family, impaired Acr3p trafficking to the plasma membrane and greatly reduced As(III) efflux, respectively. Mutagenesis of five other cysteines in Acr3p resulted in moderate reduction of As(III) transport capacities and sorting perturbations. Our data suggest that interaction of As(III) with multiple thiol groups in the yeast Acr3p may facilitate As(III) translocation across the plasma membrane.",
Arsenic,2279150,"Arsenic-induced promoter hypomethylation and over-expression of ERCC2 reduces DNA repair capacity in humans by non-disjunction of the ERCC2-Cdk7 complex Abstract: Arsenic in drinking water is of critical concern in West Bengal, India, as it results in several physiological symptoms including dermatological lesions and cancers. Impairment of the DNA repair mechanism has been associated with arsenic-induced genetic damage as well as with several cancers. ERCC2 (Excision Repair Cross-Complementing rodent repair, complementation group 2), mediates DNA-repair by interacting with Cdk-activating kinase (CAK) complex, which helps in DNA proof-reading during transcription. Arsenic metabolism alters epigenetic regulation; we tried to elucidate the regulation of ERCC2 in arsenic-exposed humans. Water, urine, nails, hair and blood samples from one hundred and fifty seven exposed and eighty eight unexposed individuals were collected. Dose dependent validation was done in vitro using HepG2 and HEK-293. Arsenic content in the biological samples was higher in the exposed individuals compared with the content in unexposed individuals (p < 0.001). Bisulfite-modified methylation specific PCR showed a significant (p < 0.0001) hypomethylation of the ERCC2 promoter in the arsenic-exposed individuals. Densitometric analysis of immunoblots showed a nearly two-fold increase in expression of ERCC2 in exposed individuals, but there was an enhanced genotoxic insult as measured by micronuclei frequency. Immuno-precipitation and western blotting revealed an increased (p < 0.001) association of Cdk7 with ERCC2 in highly arsenic exposed individuals. The decrease in CAK activity was determined by observing the intensity of Ser(392) phosphorylation in p53, in vitro, which decreased with an increase in arsenic dose. Thus we infer that arsenic biotransformation leads to promoter hypomethylation of ERCC2, which in turn inhibits the normal functioning of the CAK-complex, thus affecting DNA-repair; this effect was highest among the arsenic exposed individuals with dermatological lesions.",
Arsenic,627006,"Arsenic levels in cooked food and assessment of adult dietary intake of arsenic in the Region Lagunera, Mexico Abstract: The aim of this paper is to estimate the levels of arsenic (As) ingestion through cooked foods consumed in an arsenic endemic area and the assessment of their dietary intake of As. The study was conducted in two villages: a population chronically exposed to a high concentration of As via drinking water (410±35 ?g/l) and to a low-exposure group (12±4 ?g/l). A 24-h dietary recall questionnaire was applied to about 25 adult participants in each community. Samples of cooked food, ready for intake, were collected separately from each family's participants. To obtain the As estimate for each food item consumed, the mean quantity of food ingested in grams (wet weight) was calculated and the concentrations of total arsenic (TAs) in each cooked food were determined. The estimations of TAs intake were based on the sum over mean of As ingested from each food item consumed during the 24-h period for each participant. For the estimation of total daily As intake, we summed the mean obtained from food, plain water and hot beverage intakes. The TAs average intakes calculated for low-As-exposure group were 0.94 and 0.76 ?g/kg body weight/day, for both summer and winter exposure scenarios, respectively. These values are 44.7 and 36% of the provisional tolerable daily intake (PTDI) for inorganic arsenic (2.14 ?g/kg body weight/day), established by the World Health Organization (WHO) in 1989. The WHO reference value was obtained on a weekly basis intake estimation assuming an average body weight of 68 kg in adults. In contrast, for the high-exposure group the TAs average intakes were 16.6 and 12.3 ?g/kg body weight/day for summer and winter, respectively. Ingestion via cooked food represented 32.5 and 43.9% of the total daily As intake in the high-exposure group; for summer and winter, respectively. None the less, the bioavailability of As through food can be different than via drinking water.",
Arsenic,1353639,"Desulfonatronobacter acidivorans gen. nov., sp nov and Desulfobulbus alkaliphilus sp nov., haloalkaliphilic heterotrophic sulfate-reducing bacteria from soda lakes Abstract: ",
Arsenic,2337268,"Light Intensity Alters the Extent of Arsenic Toxicity in Helianthus annuus L. Seedlings Abstract: The present study is aimed at assessing the extent of arsenic (As) toxicity under three different light intensities-optimum (400 ?mole photon m(-2) s(-1)), sub-optimum (225 ?mole photon m(-2) s(-1)), and low (75 ?mole photon m(-2) s(-1))-exposed to Helianthus annuus L. var. DRSF-113 seedlings by examining various physiological and biochemical parameters. Irrespective of the light intensities under which H. annuus L. seedlings were grown, there was an As dose (low, i.e., 6 mg kg(-1) soil, As1; and high, i.e., 12 mg kg(-1) soil, As2)-dependent decrease in all the growth parameters, viz., fresh mass, shoot length, and root length. Optimum light-grown seedlings exhibited better growth performance than the sub-optimum and low light-grown seedlings; however, low light-grown plants had maximum root and shoot lengths. Accumulation of As in the plant tissues depended upon its concentration used, proximity of the plant tissue, and intensity of the light. Greater intensity of light allowed greater assimilation of photosynthates accompanied by more uptake of nutrients along with As from the medium. The levels of chlorophyll a, b, and carotenoids declined with increasing concentrations of As. Seedlings acquired maximum Chl a and b under optimum light which were more compatible to face As1 and As2 doses of As, also evident from the overall status of enzymatic (SOD, POD, CAT, and GST) and non-enzymatic antioxidant (Pro).",
Arsenic,1786190,"Basic mechanics of DNA methylation and the unique landscape of the DNA methylome in metal-induced carcinogenesis Abstract: DNA methylation plays an intricate role in the regulation of gene expression and events that compromise the integrity of the methylome may potentially contribute to disease development. DNA methylation is a reversible and regulatory modification that elicits a cascade of events leading to chromatin condensation and gene silencing. In general, normal cells are characterized by gene-specific hypomethylation and global hypermethylation, while cancer cells portray a reverse profile to this norm. The unique methylome displayed in cancer cells is induced after exposure to carcinogenic metals such as nickel, arsenic, cadmium, and chromium (VI). These metals alter the DNA methylation profile by provoking both hyper- and hypo-methylation events. The metal-stimulated deviations to the methylome are possible mechanisms for metal-induced carcinogenesis and may provide potential biomarkers for cancer detection. Development of therapies based on the cancer methylome requires further research including human studies that supply results with larger impact and higher human relevance.",
Arsenic,2149329,"Dynamics of arsenic in salt marsh sediments from Dongtan wetland of the Yangtze River estuary, China Abstract: ",
Arsenic,1391094,"Effects Of Metal Compounds On Mitochrondrial Function: A Review Abstract: The effects of metal compounds on mitochondrial function are reviewed. Because of a transmembrane potential, the driving force of electrophoretic cation uptake is always present in respiring mitochrondria. Heavy metals such as mercury (7439976) have been shown to increase the passive permeability of mitochrondrial membranes to cations and anions. In respiring mitochondria, heavy metals such as zinc (7440666), cadmium (7440439), copper (7440508), and lead (7439921) also activate the energy linked accumulation of potassium (7440097), which results in energy dependent swelling of mitochondria. Metals that are introduced into the biosystem as ionizable salts or that are released in-situ from organometallic compounds or complexes are usually noncompetitive inhibitors of oxido reducing and transporting enzymes, especially those rich in free SH groups. Heavy metals including mercurials, arsenate (11126322), and vanadate (37353314) have been shown to decrease, in an appropriate concentration, oxidative phosphorylation efficiency in mitochondria. Mercury is introduced into the body as inorganic salts or released in-situ from organomercurials from mercaptides with free SH groups of enzyme proteins. These are usually non competitive inhibitors of several enzyme activities in mitochondria. Lead is accumulating actively by mitochondria, in a manner similar and sometimes competitive to calcium (7440702). At high concentrations the thallous cation can cause an in-vitro uncoupling of oxidative phosphorylation. Micromolar concentrations of cadmium stimulate state 4 respiration and uncouple oxidative phosphorylation in liver mitochondria, whereas higher concentrations inhibit respiration. Zinc cations at less than 5 micromolar concentrations cause stimulation of state 4 oxygen uptake by coupled mitochondria. The swelling of mitochondria induces an increased accumulation of copper. Iron (7439896) cations are bound to and accumulate in mitochondria by energy independent and dependent mechanisms. Manganous cations are bound to and are accumulated by isolated mitochondria in a respiration dependent manner. The authors suggest that heavy metal toxicants affect mitochondrial function in a variety of molecular mechanisms.",
Arsenic,2337196,"Noninvasive aneuploidy detection by multiplexed amplification and sequencing of polymorphic Loci Abstract: <strong>INTRODUCTION: </strong>We determined performance of a massively multiplexed polymerase chain reaction assay targeting single nucleotide polymorphisms in identifying fetal trisomies 21, 18, 13 and monosomy X from cell-free DNA isolated from maternal plasma.<br /><br /><strong>METHODS: </strong>Cell-free DNA was isolated from 1,050 pregnant women (including 490 externally blinded, 519 low-risk, and 124 aneuploid samples) and analyzed. A total of 19,488 single nucleotide polymorphisms covering chromosomes 13, 18, 21, X, and Y were amplified in a single multiplex polymerase chain reaction and sequenced. Results were analyzed using the Next-generation Aneuploidy Test Using Single nucleotide polymorphism algorithm, which uses Bayesian statistics and incorporates parental genotypes. Next-generation Aneuploidy Test Using Single nucleotide polymorphism algorithm calculates sample-specific accuracies without requiring reference chromosomes.<br /><br /><strong>RESULTS: </strong>This method reported 100% sensitivity for trisomy 21 (58/58), trisomy 18 (24/24), trisomy 13 (12/12), and fetal sex (775/775) and 90% sensitivity for monosomy X (9/10). Specificity for trisomies 21 and 13 was 100% (904/904 and 952/952, respectively) and for trisomy 18 and monosomy X was 99.9% (938/939 and 952/953, respectively). Accurate copy number calls were made at 7 weeks of gestation, as low as 3.8% fetal fraction, and sensitivity and specificity were perfect in the low-risk cohort. &quot;Extremely low fetal fraction&quot; samples (less than the first percentile, maternal weight- and gestational age-adjusted) were greater than 12 times more likely to be abnormal (odds ratio 12.6).<br /><br /><strong>CONCLUSIONS: </strong>Multiplexing 19,488 single nucleotide polymorphism-targeted assays in a single polymerase chain reaction accurately identified fetal aneuploidies from cell-free DNA with unparalleled performance. This approach thus enables highly accurate, noninvasive, early prenatal aneuploidy detection and suggests that extremely low fetal fraction may identify a new category of pregnancies at risk of fetal or placental abnormality.",
Arsenic,1256735,"Heavy metal and disinfectant resistance of Listeria monocytogenes from foods and food processing plants Abstract: The persistence of Listeria monocytogenes in food processing plants and other ecosystems reflects its ability to adapt to numerous stresses. In this study, we investigated 138 isolates from foods and food processing plants for resistance to the quaternary ammonium disinfectant benzalkonium chloride (BC) and to heavy metals (cadmium and arsenic). We also determined the prevalence of distinct cadmium resistance determinants (cadA1, cadA2 and cadA3) among cadmium-resistant isolates. Most BC-resistant isolates were resistant to cadmium as well. Arsenic resistance was encountered primarily in serotype 4b and was an attribute of most isolates of the serotype 4b epidemic clonal group ECIa. Prevalence of the known cadmium resistance determinants was serotype-associated: cadA1 was more common in isolates of serotype 1/2a and 1/2b than 4b while cadA2 was more common in those of serotype 4b. A subset (15/77, 19%) of the cadmium-resistant isolates lacked the known cadmium resistance determinants. Most of these isolates were of serotype 4b and were also resistant to arsenic, suggesting novel determinants that may confer resistance to both cadmium and arsenic in these serotype 4b strains. The findings may reflect previously unrecognized components of the ecological history of different serotypes and clonal groups of L. monocytogenes, including exposures to heavy metals and disinfectant.",
Arsenic,1353286,APPLICATION OF IRON-OXIDIZING BACTERIA TO HYDROMETALLURGICAL FLUE DUST TREATMENT AND H2S DESULFURIZATION Abstract: ,
Arsenic,2064221,Arsenic levels in chicken: nachman et Al. Respond Abstract: ,
Arsenic,1677531,"Arsenic exposure and cancer mortality in a US-based prospective cohort: The strong heart study Abstract: Background: Inorganic arsenic, a carcinogen at high levels, is a major global health problem. Prospective studies on carcinogenic effects at low-moderate arsenic levels are lacking. Methods: We evaluated the association between baseline arsenic exposure and cancer mortality in 3,932 American Indians 45-74 years from Arizona, Oklahoma and North/South Dakota who participated in the Strong Heart Study in 1989-1991 and were followed through 2008. We estimated inorganic arsenic exposure as the sum of inorganic and methylated species in urine. Cancer deaths (386 overall, 78 lung, 34 liver, 18 prostate, 26 kidney, 24 esophagus/stomach, 25 pancreas, 32 colon/rectal, 26 breast, 40 lymphatic/hematopoietic) were assessed by mortality surveillance reviews. We hypothesized an association with lung, liver, prostate and kidney cancer. Results: Median (interquartile range) urine concentration for inorganic plus methylated arsenic species was 9.7 (5.8-15.6) µg/g creatinine. The adjusted hazard ratios (95% CI) comparing the 80th versus 20th percentiles of arsenic were 1.14 (0.92-1.41) for overall cancer, 1.56 (1.02-2.39) for lung cancer, 1.34 (0.66, 2.72) for liver cancer, 3.30 (1.28-8.48) for prostate cancer, and 0.44 (0.14, 1.14) for kidney cancer. The corresponding hazard ratios were 2.46 (1.09-5.58) for pancreatic cancer, and 0.46 (0.22-0.96) for lymphatic and hematopoietic cancers. Arsenic was not associated with cancers of the esophagus and stomach, colon and rectum, and breast. Conclusions: Low to moderate exposure to inorganic arsenic was prospectively associated with increased mortality for cancers of the lung, prostate and pancreas. Impact: These findings support the role of low-moderate arsenic exposure in lung, prostate and pancreas cancer.",
Arsenic,1015664,"Influence of glutathione chemical effectors in the response of maize to arsenic exposure Abstract: To support the key role of glutathione (GSH) in the mechanisms of tolerance and accumulation of arsenic in plants, this work examines the impact of several effectors of GSH synthesis or action in the response of maize (Zea mays L.) to arsenic. Maize was exposed in hydroponics to iso-toxic rates of 150?M arsenate or 75?M arsenite for 9days and GSH effectors, flurazole (an herbicide safener), l-buthionine-sulfoximine (BSO, a known inhibitor of GSH biosynthesis), and dimercaptosuccinate (DMS) and dimercaptopropanesulfonate (DMPS) (two thiols able to displace GSH from arsenite-GSH complexes) were assayed. The main responses of plants to arsenic exposure consisted of a biomass reduction (fresh weight basis) of about 50%, an increase of non-protein thiol (NPTs) levels (especially in the GSH precursor ?-glutamylcysteine and the phytochelatins PC(2) and PC(3)) in roots, with little effect in shoots, and an accumulation of between 600 and 1000ppm of As (dry weight basis) in roots with very little translocation to shoots. Growth inhibition caused by arsenic was partially or completely reversed in plants co-treated with flurazole and arsenate or arsenite, respectively, highly exacerbated in plants co-treated with BSO, and not modified in plants co-treated with DMS or DMPS. These responses correlated well with an increase of both NPTs levels in roots and glutathione transferase activity in roots and shoots due to flurazole treatment, the decrease of NPTs levels in roots caused by BSO and the lack of effect on NPT levels caused by both DMS and DMPS. Regarding to arsenic accumulation in roots, it was not modified by flurazole, highly reduced by BSO, and increased between 2.5- and 4.0-fold by DMS and DMPS. Therefore, tolerance and accumulation of arsenic by maize could be manipulated pharmacologically by chemical effectors of GSH.",
Arsenic,1340072,"Impairment of antioxidant defenses as a contributor to arsenite-induced cell transformation Abstract: Arsenite (As) causes transformation of human osteogenic sarcoma cells (HOS) when applied continuously at low doses (0.1-0.5 ?M) during 8-weeks of exposure. However, the mechanisms by which As transforms human cells are not known. We investigated whether alterations occurred in gene expression and protein levels of antioxidant defense proteins, such as superoxide dismutase 1 (SOD1) and ferritin. In comparison to control HOS cells, 0.1 ?M As induced greater cell proliferation and decreased anti-oxidant defenses. The tumor suppressor protein p53 was also decreased at both mRNA and protein levels. Further, pig3 (p53-induced-gene 3), a homolog of NQO1 (NADPH quinone oxidoreductase 1), was also down-regulated after 8 weeks of As challenge. The treatment of HOS cells with dicumarol, a NQO1 inhibitor, caused a dose-dependent decline in p53 protein levels, proving the effect of an antioxidant enzyme on p53 expression and, potentially, down-stream processes. Caffeic acid phenethyl ester, an antioxidant, prevented the As-induced decreases in SOD1, p53, and ferritin mRNA and protein levels. SOD1, p53 and ferritin levels were inversely related to As-induced cell proliferation. Cumulatively, these results strongly suggest that impairment in antioxidant defenses contributes to As-induced human cell transformation and that the p53 pathway is involved in the process.",
Arsenic,2345662,"Low incidence of late pseudoaneurysm and reoperation after conventional repair of acute type A aortic dissection Abstract: <strong>BACKGROUND AND AIM: </strong>Suture line dehiscence and pseudoaneurysm formation is one of the leading causes of late reoperation after surgical repair of acute type A aortic dissection (AAD). A sandwich technique can affect the need of reoperation. We sought to assess the late outcomes (mortality and reoperation) of a modified reinforced sandwich technique in conventional AAD repair.<br /><br /><strong>METHODS: </strong>Retrospective review of 63 consecutive patients undergoing AAD repair between 2003 and 2013. Aortic anastomosis was performed with a modified reinforced sandwich technique using Hemashield strips and two-layer polypropylene continuous and interrupted mattress sutures.<br /><br /><strong>RESULTS: </strong>Marfan syndrome was diagnosed in five (8%) and bicuspid aortic valve in three patients (5%). Twenty-one patients (33%) had preoperative cardiogenic shock necessitating inotropic support. Replacement of the ascending aorta with aortic valve preservation was performed in 58 (92%) and hemiarch replacement in five patients (8%). Four patients died during initial hospitalization, yielding a hospital mortality of 6%. Median follow-up duration was 73 months (range, 1-124). Kaplan-Meier survival rates were 94?±?3%, 84?±?5%, and 59?±?11% at 1, 5, and 10 years. One patient (1.7%) required proximal reoperation 44 months after AAD repair because of progressive dilatation of the aortic root. No patient had severe aortic regurgitation or pseudoaneurysm after AAD repair. Actuarial freedom from reoperation at 1, 5, and 10 years was 100%, 97%, and 97%.<br /><br /><strong>CONCLUSIONS: </strong>A reinforced sandwich technique was a good technique resulting in a low incidence of late reoperation and pseudoaneurysm formation.",
Arsenic,627266,"Defective adrenergic responses in patients with arsenic-induced peripheral vascular disease Abstract: Blackfoot disease is an endemic arsenic-induced peripheral vascular disease in southern Taiwan. The main pathologic feature is atherosclerosis, which may relate to imbalances of the adrenergic system. The purpose of this study is to investigate the peripheral adrenergic responses of patients with blackfoot disease. Eight patients with blackfoot disease and four age-matched healthy controls were enrolled in this study. Baseline cutaneous perfusion was measured with a laser Doppler flowmeter. The response of alpha-adrenoceptors in the cutaneous microcirculation was assessed with laser Doppler flowmetry with iontophoresis of phenylephrine into the nailfold. In vitro binding with (125)I-cyanopindolol determined beta-adrenoceptor density in lymphocytes. The cyclic adenosine monophosphate (cAMP) level at baseline and after isoproterenol stimulation reflects lymphocyte beta-adrenergic responsiveness. Results revealed persistently decreased skin perfusion in patients with blackfoot disease. In contrast, there was a transient decrease in skin perfusion in healthy controls after iontophoresis of phenylephrine. Both beta-2 receptor density and isoproterenol-stimulated cAMP levels in lymphocytes decreased. Increased peripheral alpha-adrenergic response and decreased beta-2-adrenergic response are related to increased vascular tone and result in atherosclerosis. Our findings of accentuated alpha-adrenergic response in microcirculation and decreased lymphocyte beta-2-adrenoceptor response play an important role in the pathogenesis of atherosclerosis in blackfoot disease.",
Arsenic,2298707,"Surface water characterization of three rivers in the lead/zinc mining region of northeastern macedonia Abstract: Mine waste is recognized as being one of the most serious threats for freshwater ecosystems, and it still represents one of the greatest environmental concerns in Macedonia. The aim of our investigation was to obtain an in-depth understanding of mining influence on freshwater systems from water contamination to effects on aquatic organisms. In this study, we assessed the impact of active lead (Pb)/zinc (Zn) mines Zletovo and Toranica on the water quality of three rivers in northeastern Macedonia (Bregalnica, Zletovska, and Kriva rivers) based on data collected in spring and autumn of 2012. The Bregalnica River, near Shtip, was characterized mainly by weak contamination with arsenic, barium, iron, molybdenum, titanium, uranium, vanadium, nitrate, and phosphate, as well as critical faecal pollution, which alltogether could be connected to agricultural activities; however, an impact of the mines was not observed. Contrary, both the Zletovska and Kriva rivers showed a clear impact of Pb/Zn mines on water quality. In the Zletovska River, increased concentrations of cadmium (Cd), cobalt, cesium, copper, lithium, manganese (Mn), nickel, rubidium, tin, strontium, thallium, Zn, sulphates, and chlorides were found, especially in autumn (e.g., Cd 2.0 ?g L(-1); Mn 2.5 mg L(-1); Zn 1.5 mg L(-1)). In the Kriva River, increased Cd (0.270 ?g L(-1)) and Pb (1.85 ?g L(-1)) concentrations were found only in spring, possibly due to sediment resuspension during greater water discharge. The selected sampling sites on the Bregalnica, Zletovska, and Kriva rivers were confirmed as being appropriate locations for further studies of mining waste's impact on freshwater ecosystems, the first one as a nonimpacted site and the other two as possible areas of increased exposure of aquatic organisms to metals.",
Arsenic,628366,"Effect of chronic arsenic exposure from drinking waters on the QT interval and transmural dispersion of repolarization Abstract: This study investigated the effects of chronic arsenic exposure on QT- and QTc-interval prolongation, QTc dispersion (QTcd) and transmural dispersion of repolarization (TDR). We compared cardiac parameters from 40 male subjects chronically exposed to arsenic (group A) with those of 40 male subjects not exposed to arsenic (group B). Although subjects in both groups had non-corrected QT intervals within normal limits, subjects in group A had significantly longer QTc and QTcd intervals compared with group B. A total of 70% of group A compared with 10% of group B had QTcd values > 50 ms. The mean TDR value was also significantly higher in group A compared with group B. Although non-corrected QT intervals were within normal limits, those subjects chronically exposed to arsenic had a slight QT prolongation and a higher prevalence of subtle repolarization abnormalities, which might be clinically relevant.",
Arsenic,1508524,"Measurement modelling and mapping of arsenic bioaccessibility in Northampton, United Kingdom Abstract: The human ingestion bioaccessibility of As was measured on 50 representative samples of soils selected from a 281-soil-sample geochemical survey of Northampton. The major and trace element content, pH and near infrared (NIR) spectra of the 281 soils were determined. A multiple linear regression (MLR) model using total As, major element composition and pH identified total As, pH and P to be the significant predictor variables for bioaccessible As (R2 = 0.72, median standard error of prediction = 1.5 mg kg(-1) bioaccessible As). When spectral components (SC) derived from chemometric analysis of the NIR spectra were also included in the MLR, total As, pH, Mg and two NIR spectral components were found to be significant predictor variables (R2 = 0.84, median standard error of prediction = 1.2 mg kg(-1) bioaccessible As). Correlation analysis of the SC with major element data suggested that the two NIR SC in the second model were related to different forms of Fe oxides in the soil. When plotted over a geological map of Northampton interpolated predictions of bioaccessible As showed clear geological control. The median total As concentration of the soils in Northampton was 30.2 mg kg(-1) and the median bioaccessible As was 3.0 mg kg(-1).",
Arsenic,1020420,"Changes in gene expression profiles of human fibroblasts in response to sodium arsenite treatment Abstract: Arsenic compounds are widely distributed and arsenic ingestion is associated with many human diseases, including blackfoot disease, atherosclerosis, and cancers. However, the underlying mechanism of arsenic toxicity is not understood. In human fibroblast cells (HFW), arsenite is known to induce oxidative damage, chromosome aberrations, cell cycle arrest, and aneuploidy, and the manifestation of these cellular responses is dependent on changes in gene expression which can be analyzed using the cDNA microarray technique. In this study, cDNA microarray membranes with 568 human genes were used to examine mRNA profile changes in HFW cells treated for 0 to 24 h with 5 microM sodium arsenite. On the basis of the mean value for three independent experiments, 133 target genes were selected for a 2 x 3 self-organizing map cluster analysis; 94 were found to be induced by arsenite treatment, whereas 39 were repressed. These genes were categorized as signal transduction, transcriptional regulation, cell cycle control, stress responses, proteolytic enzymes, and miscellaneous. Significant changes in the signaling-related and transcriptional regulation genes indicated that arsenite induces complex toxicopathological injury.",
Arsenic,1020414,"A major human arsenic metabolite, dimethylarsinic acid, requires reduced glutathione to induce apoptosis Abstract: Inorganic arsenicals are important environmental toxicants and carcinogens in humans. In mammals, including humans, inorganic arsenicals often undergo methylation, forming compounds such as dimethyarsinic acid (DMA). Recent evidence indicates DMA is a complete carcinogen in rodents while evidence for inorganic arsenicals as carcinogens in rodents remains equivocal. Thus, we studied the molecular mechanisms of in vitro cytolethality of DMA compared to that of the trivalent inorganic arsenical, sodium arsenite, using a rat liver epithelial cell line (TRL 1215). Arsenite was very cytotoxic in these cells (LC(50) = 35 microM after 48 h of exposure). With arsenite exposure, most dead cells showed histological and biochemical evidence of necrosis. Arsenite cytotoxicity increased markedly when cellular GSH was depleted with the glutathione synthase inhibitor, L-buthionine-[S,R]-sulfoximine (BSO). In contrast, DMA was nearly 3 orders of magnitude less cytotoxic (LC(50) = 1.5 mM) although evidence showed the predominating form of death was apoptosis. Surprisingly, GSH depletion actually decreased DMA-induced apoptosis. A glutathione scavenger, diethyl maleate (DEM), and a glutathione reductase inhibitor, carmustine, also prevented DMA-induced apoptosis. These data indicate that DMA requires intracellular GSH to induce apoptosis. Ethacrynic acid (EA), an inhibitor of glutathione S-transferase (GST) that catalyzes GSH-substrate conjugation, acivicin, an inhibitor of gamma-glutamyltranspeptidase (GGT) which catalyzes the initial breakdown of GSH-substrate conjugates, and aminooxyacetic acid (AOAA), an inhibitor of beta-lyase which catalyzes the final breakdown of GSH-substrate conjugates, all were effective in suppressing DMA-induced apoptosis. These findings indicate that DMA likely is conjugated in some form with GSH, and that it is this conjugate that induces apoptosis during subsequent metabolic reactions.",
Arsenic,628060,"Involvement of substance P and neurogenic inflammation in arsenic-induced early vascular dysfunction Abstract: Vascular-related diseases, including Blackfoot Disease and atherosclerosis, are prominent clinical findings among populations residing in arseniasis areas. While oxidative stress provided a general but nonspecific mechanistic base for arsenic-induced endothelial cell damage in vitro, more specific mechanism is needed to explain the highly targeted vascular lesions induced by arsenic in vivo. Based on our previous studies, we hypothesized that arsenic exerted its action on blood vessels via the neurogenic inflammation process involving release of a neuropeptide (substance P) and activation of endothelial Neurokinin 1 (NK-1) receptor in vivo. Indeed, our present study demonstrated a significantly higher substance P levels in arsenic-treated tissues when compared to saline-treated controls indicating a rapid release of substance P under the influence of arsenic. Furthermore, the arsenic-induced vascular leakage could be significantly reduced when the neurogenic inflammation process was interrupted (via either disruption on the release of substance P, interference on the action of substance P, or blockage of endothelial NK-1 receptor) showing that the neurogenic inflammation process was indeed involved. Histamine release was not found to play a significant role in arsenic-induced vascular permeability change. Our present study affirmed a de novo concept that a pathophysiological mechanism involving the neurogenic release of substance P and activation of endothelial NK-1 receptor underlies the arsenic-induced vascular injury and dysfunction in vivo. This pathophysiological process constituted a two-tiered biological interaction between the nervous system and vascular system and therefore was not readily unveiled by traditional in vitro studies in the past. Our present finding unveiled an important de novo concept on arsenic vascular toxicity in vivo.",
Arsenic,1016807,"Biological monitoring of exposures to aluminium, gallium, indium, arsenic, and antimony in optoelectronic industry workers Abstract: The main objective of this study was to investigate aluminum, gallium, indium, arsenic, and antimony exposures on blood and urine levels in the optoelectronic workers. One hundred seventy subjects were enrolled in this cohort study. Whole blood and urine levels were determined by inductively coupled plasma-mass spectrometry. Blood indium and urine gallium and arsenic levels in the 103 workers were significantly higher than that in 67 controls during the follow-up period. In regression models, the significant risk factors of exposure were job title, preventive equipment, Quetelet's index, sex, and education level. The findings of this study suggest that gallium, indium, and arsenic exposure levels may affect their respective levels in blood and urine. The use of clean, preventive equipment is recommended when prioritizing the administration of safety and hygiene in optoelectronics industries.",
Arsenic,1519063,"Evaluation of pollution in Camichin estuary (Mexico): Pro-oxidant and antioxidant response in oyster (Crassostrea corteziensis) Abstract: The physiological system of molluscs, particularly pro-oxidant and antioxidant mechanisms, could be altered by pollutants and induce disturbance on health status and productive parameters of aquatic organisms, such as oyster. Therefore, the aim of this study was to evaluate the chemical contamination in water (total metals and polycyclic aromatic hydrocarbons) and oxidative stress parameters in oysters (Crassostrea corteziensis) in Camichin estuary, located in Mexican Tropical Pacific. The results obtained showed the presence of arsenic, lead and zinc, as well as naphthalene, pyrene and benzo[a]pyrene in concentrations relatively higher than criteria established by local and international guidelines. Regarding the biomarkers of oxidative stress response (H2O2 and O2 concentration, catalase activity, lipid peroxidation, and hydroperoxide concentration), differences between oyster from estuary and control group were significant. These results indicate that these pollutants could be related with oxidative stress detected in oyster.",
Arsenic,2278627,"Stinging nettle (Urtica dioica L.) growth and mineral uptake from lead-arsenate contaminated orchard soils Abstract: Growth and mineral uptake was studied in stinging nettle (Urtica dioica L.) grown on lead-arsenate contaminated orchard soils. Six soil samples including a non-orchard control were used. Uniform U. dioica seedlings were transplanted into pots arranged in a completely randomized design and raised under uniform greenhouse conditions. Shoots were harvested at day 26, and shoot (harvest 2) and root portions 50 days after transplanting. All samples were oven dried, weighed, and processed for mineral analysis. Elevated arsenic levels in soil did not significantly affect nettle growth except at the highest concentration of 163 mg kg?1. There was arsenic bio-concentration in U. dioica roots and high levels of arsenic and lead in both below- and aboveground tissues. Stinging nettle is a plant of economic importance harvested for food and medicine. Our results show that humans can be exposed to toxic levels of arsenic and lead through contaminated nettle products.",
Arsenic,1597347,"Arsenic bioremediation by biogenic iron oxides and sulfides Abstract: Microcosms containing sediment from an aquifer in Cambodia with naturally elevated levels of arsenic (As) in the associated groundwater were used to evaluate the effectiveness of microbially-mediated production of iron minerals for in situ As remediation. The microcosms were first incubated without amendments for 28 days and the release of As and other geogenic chemicals from the sediments into the aqueous phase was monitored. Nitrate, or a mixture of sulfate and lactate, was then added to stimulate biological Fe(II) oxidation or sulfate reduction, respectively. Without treatment soluble As concentrations reached 3.9 (±0.9) ?M at the end of the 143 day experiment. However, in the nitrate and sulfate plus lactate amended microcosms, soluble As levels decreased to 0.01 and 0.41(±0.13) ?M, respectively, by the end of the experiment. Analyses using a range of biogeochemical and mineralogical tools, indicated that sorption onto freshly formed hydrous ferric oxide (HFO) and iron sulfide mineral phases are the likely mechanisms for As removal in the respective treatments. Incorporation of the experimental results into a one-dimensional transport-reaction model suggests that, under conditions representative of the Cambodian aquifer, the in situ precipitation of HFO would be effective in bringing groundwater into compliance with the World Health Organization (WHO) provisional guideline value for As (10 ppb or 0.13 ?M), although soluble Mn release accompanying microbial Fe(II) oxidation presents a potential health concern. In contrast, production of biogenic iron sulfide minerals would not remediate the groundwater As concentration below the recommended WHO limit.",
Arsenic,627882,"Ecological correlation between arsenic level in well water and age-adjusted mortality from malignant neoplasms Abstract: A significant dose-response relation between ingested arsenic and several cancers has recently been reported in four townships of the endemic area of blackfoot disease, a unique peripheral artery disease related to the chronic arsenic exposure in southwestern Taiwan. This study was carried out to examine ecological correlations between arsenic level of well water and mortality from various malignant neoplasms in 314 precincts and townships of Taiwan. The arsenic content in water of 83,656 wells was determined by a standard mercuric bromide stain method from 1974 to 1976, while mortality rates of 21 malignant neoplasms among residents in study precincts and townships from 1972 to 1983 were standardized to the world population in 1976. A significant association with the arsenic level in well water was observed for cancers of the liver, nasal cavity, lung, skin, bladder and kidney in both males and females as well as for the prostate cancer in males. These associations remained significant after adjusting for indices of urbanization and industrialization through multiple regression analyses. The multivariate-adjusted regression coefficient indicating an increase in age-adjusted mortality per 100,000 person-years for every 0.1 ppm increase in arsenic level of well water was 6.8 and 2.0, 0.7 and 0.4, 5.3 and 5.3, 0.9 and 1.0, 3.9 and 4.2, as well as 1.1 and 1.7, respectively, in males and females for cancers of the liver, nasal cavity, lung, skin, bladder and kidney. The multivariate-adjusted regression coefficient for the prostate cancer was 0.5. These weighted regression coefficients were found to increase or remain unchanged in further analyses in which only 170 southwestern townships were included.",
Arsenic,1519147,Evaluation of heavy metals content in dietary supplements in Lebanon Abstract: ,
Arsenic,1377988,"Arsenite Induces Procoagulant Activity In Human Platelets By Phosphatidylserine Exposure And Microparticle Generation Abstract: Many epidemiological studies reported that there are strong correlations between arsenic in drinking water and occurrences of cardiovascular disease as well as human cancer, but the exact mechanism is not clearly known. We investigated if arsenic can affect procoagulant activity of platelet, which is essential in blood clotting, thrombus formation and cardiovascular disease development. Effects of arsenic on platelet procoagulant activities are examined in vitro using human platelets and in vivo in a rat animal model. Arsenite significantly enhanced platelet procoagulant activity induced by thrombin in a concentration- and time-dependent manner as observed in prothrombinase assay. It is generally considered that the increase of procoagulant activity is mediated by exposure of anionic phospholipids (phosphatidylserine; PS) and microparticle (MP) generation. In flow cytometry analysis, we found that arsenite enhanced PS exposure and MP formation induced by thrombin. Generated MPs were also confirmed in confocal microscopy and found to have procoagulant activity like PS-exposed platelets. These effects of arsenic appeared to be mediated by enhanced calcium increase as investigated with Fluo-3. Pretreatment of calpeptin, a calpain inhibitor, abolished arsenic effects on platelets showing that calpain is involved in these processes. In addition, arsenite inhibited aminophospholipid translocase, suggesting exposed PS could be maintained in outer membranes. Consistent with arsenite-enhanced platelet procoagulant activity observed in vitro, arsenite infusion actually led to the increase of thrombus formation in vivo in rat venous thrombosis model. In conclusion, arsenite induces enhancement of procoagulant activity with the increase of PS exposure and MP formation in human platelets and resultant venous thrombosis as observed in vivo. These enhanced platelet procoagulant activity may be a major contributing factor in cardiovascular disease associated with chronic intake of arsenic in drinking water through enhanced blood clotting and thrombus formation.",
Arsenic,2337089,"Response of Pteris vittata to different cadmium treatments Abstract: Pteris vittata is known as an arsenic hyperaccumulator, but there is little information about its tolerance to cadmium and on its ability to accumulate this heavy metal. Our aim was to analyse the accumulation capacity, oxidative stress and antioxidant response of this fern after cadmium treatments. Cadmium content, main markers of oxidative stress and antioxidant response were detected in leaves of plants grown in hydroponics for both short- (5 days) and long- (15 days) term exposure to 0 (control) 60 and 100 mu M CdCl2. In leaves, the concentration of cadmium and oxidative stress were parallel with the increase of cadmium exposure. In the short-term exposure, antioxidant response was sufficient to contrast cadmium phytotoxicity only in 60 mu M cadmium-treated plants. In the long-term exposure all treated plants, in spite of the increase in activity of some peroxide-scavenging enzymes, showed a significant increase in oxidative damage. As in the long-term stress markers were comparable in all treated plants, with no clear correlation with hydrogen peroxide content, at least part of cadmium-induced oxidative injury seems not mediated by H2O2. Based on our studies, P. vittata, able to uptake relatively high concentrations of cadmium, is only partially tolerant to this heavy metal.",
Arsenic,1936130,"Optimization of arsenic and pentachlorophenol removal from soil using an experimental design methodology Abstract: In this study, a soil-washing process was investigated for arsenic (As) and pentachlorophenol (PCP) removal from polluted soils. This research first evaluates the use of chemical reagents (HCl, HNO3, H2SO4, lactic acid, NaOH, KOH, Ca(OH)(2), and ethanol) for the leaching of As and PCP from polluted soils. A Box-Behnken experimental design was used to optimize the main operating parameters for soil washing. A laboratory-scale leaching process was applied to treat four soils polluted with both organic ([PCP] (i) = 2.5-30 mg kg(-1)) and inorganic ([As] (i) = 50-250 mg kg(-1), [Cr] (i) = 35-220 mg kg(-1), and [Cu] (i) = 80-350 mg kg(-1)) compounds. Removals of 72-89, 43-62, 52-68, and 64-98 % were obtained for As, Cr, Cu, and PCP, respectively, using the optimized operating conditions ([NaOH] = 1 N, [cocamidopropylbetaine] (i) = 2 % w w(-1), t = 2 h, T = 80 A degrees C, and PD = 10 %). The use of NaOH, in combination with the surfactant, is efficient in reducing both organic and inorganic pollutants from soils with different levels of contamination.",
Arsenic,627148,"Dead or dying: The importance of time in cytotoxicity assays using arsenite as an example Abstract: Arsenite is a toxicant and environmental pollutant associated with multisite neoplasias and other health effects. The wide range of doses used and the claims that some high doses are ""not toxic"" in some assays have confounded studies on its mechanism of action. The purpose of this study is to determine whether the treatment time and particularly the duration between treatment and assay are important factors in assessing arsenite toxicity. We compared three commonly used assays: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), neutral red (NR), and clonal survival, using human osteogenic sarcoma (HOS) cell line U-2OS. Results from the assays were well correlated only when the factor of time was taken into account. In both the MTT and NR assays, exposure to arsenite for 24 h induced much less toxicity than exposure for 48 or 72 h, which gave similar results. In contrast, results in clonal survival assays showed only a small difference between 24-h exposure and longer exposure times. Arsenite demonstrated delayed cytotoxicity, killing the cells even after its removal from the medium in NR assay. Apoptosis was assessed by TUNEL staining and caspase-3 activation. After treatment for 24 h with 0.1 and 1 microM arsenite, no apoptosis was seen. However, after an additional 24 h in arsenite-free medium, a small amount of apoptosis could be detected, and much more apoptosis was seen after 48 h. In contrast, 10 microM arsenite triggered rapid necrosis and failed to activate caspase 3 or cause TUNEL staining. We also confirmed previous reports that exposure to low concentrations of arsenite caused transient stimulation of cell growth. Our finding of delayed toxicity by arsenite suggests that to avoid underestimation of toxicity, the duration between treatment and assay should be taken into account in choosing appropriate doses for arsenite as well as for other toxicants that may show similar delayed toxicity. The NR and MTT assays should be performed only after an interval of at least 48 h after a 24-h exposure to arsenite.",
Arsenic,627301,"Association between multi-level inorganic arsenic exposure from drinking water and skin lesions in China Abstract: Arsenic is one of the most important toxicants in the environment. In Inner Mongolia of China, 300,000 residents are believed to be drinking water containing >50 microg/liter. Skin lesions have been known as the most common consequences resulting from chronic exposure to arsenic. To clarify the prevalence of arsenic-induced skin lesions, it is important to assess the impact of this problem among the target population, and to make future planning. We evaluated the association between multi-levels inorganic arsenic exposure from drinking water and skin lesions in an arsenic-affected area in Inner Mongolia, China. One hundred nine and 32 subjects in high (>50 microg/liter) and low (<50 microg/liter) arsenic-affected villages were recruited and had the detailed physical examination with special emphasis on arsenic-related skin lesions. Arsenic exposure was measured for each participant with respect to iAs concentration of primary well and the duration using the well. Arsenic-induced skin lesions including keratosis, pigmentation, and/or depigmentation were diagnosed in 56 and 3 subjects in the two villages, respectively. Logistic regression was conducted to calculate odd ratios of skin lesions associated with arsenic exposure with adjustments for sex, age group, smoking and duration of exposure. A consistent dose-response relationship between arsenic exposure level and skin lesion risk was observed. Compared to those with iAs concentration <50 microg/liter, the adjusted odds ratios of skin lesions for the subjects with 51-99, 100-149 and >150 microg/liter were 33.3% (OR =15.50, 95% CI: 1.53-248.70), 46.7% (OR =16.10, 95% CI: 3.73-69.63) and 55.7% (OR= 25.70, 95% CI: 6.43-102.87), respectively. Duration of using well was not associated with increased risk of skin lesions in this population; (OR =1.68, 95% CI: 0.40-6.91 for 6-15 years, OR = 2.30, 95% CI: 0.58-9.14 for over 15 years) compared with the duration of less than 5 years.",
Arsenic,2149257,"EFFECTS OF ADDING NITROPRUSSIDE ON ARSENIC STRESSED RESPONSE OF PISTIA STRATIOTES L. UNDER HYDROPONIC CONDITIONS Abstract: Effect of nitric oxide (NO) in mitigating stress induced by arsenic (As) was assessed in Pistia stratiotes, with NO supplied as sodium nitroprusside (SNP). Plants were exposed to four treatments: control, SNP (0.1mg L-1), As (1.5mg L-1), As + SNP (1.5 and 0.1mg L-1), for seven days (analyses of growth, absorption of As and mineral nutrients) and for 24h (analyses of concentration of reactive oxygen intermediates (ROIs), antioxidant capacity and photosynthesis). P. stratiotes accumulated high concentrations of As and this accumulation wasn't affected by the addition of SNP, but the tolerance index of the plant to As increased. SNP attenuated effects of As on the absorption of mineral nutrients (Ca, Fe, Mn, and Mg), but not for phosphorus, and maintained concentrations of ROIs to normal levels, probably due to the increase in antioxidant capacity. The As damaged the photosynthesis by the decrease in pigment contents and by disturbance the photochemical (loss of PSII efficiency and increases in non-photochemical quenching coefficient) and biochemical (reductions in carbon assimilation, increase in the C-i/C-a and (PSII)/phi(CO2) ratios) steps. The addition of SNP restored these parameters to normal levels. Thus, NO was able to increasing the resistance of P. stratiotes to As. Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.",
Arsenic,1339188,"Delineating the degree of association between biomarkers of arsenic exposure and type-2 diabetes mellitus Abstract: Non-carcinogenic effects in low-level (&lt;100?gL(-1)) arsenic (As)-impacted populations, such as the development and progression of type-2 diabetes mellitus (T2DM), are often neglected given the primary emphasis of public health authorities on As carcinogenicity. We gathered studies reporting urinary biomarkers of As exposure (U-As) and biomarkers associated with T2DM and its complications (U-T2DM), such as renal damage, oxidation stress, low-grade inflammation, and endothelial damage. Studied U-T2DM biomarkers were: 8-hydroxy-2'deoxyguanosine, N-acetyl-?-d-glucosaminidase, ?2-microglobulin, and albumin. Data was expressed as: either arithmetic means and standard deviations, or geometric means and geometric standard deviations, or correlation coefficients of U-As and U-T2DM. Urinary As concentrations were consistently associated with the aforementioned biomarkers of T2DM pathologic complications. Despite the limited selectivity of the selected T2DM biomarkers, a per unit change in As exposure level was reflected in the corresponding T2DM biomarker urinary concentrations. Our systematic review provides new evidence on the role of environmental As exposures influencing the T2DM disease process. Additional epidemiologic studies onto the association between As and T2DM should incorporate both urinary As and T2DM biomarkers, as suggested in this study, in order to evaluate subclinical effects of low-level As exposures.",
Arsenic,1021651,"Urinary arsenic metabolites of subjects exposed to elevated arsenic present in coal in Shaanxi Province, China Abstract: In contrast to arsenic (As) poisoning caused by naturally occurring inorganic arsenic-contaminated water consumption, coal arsenic poisoning (CAP) induced by elevated arsenic exposure from coal combustion has rarely been reported. In this study, the concentrations and distributions of urinary arsenic metabolites in 57 volunteers (36 subjects with skin lesions and 21 subjects without skin lesions), who had been exposed to elevated levels of arsenic present in coal in Changshapu village in the south of Shaanxi Province (China), were reported. The urinary arsenic species, including inorganic arsenic (iAs) [arsenite (iAsIII) and arsenate (iAsV)], monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV), were determined by high-performance liquid chromatography (HPLC) combined with inductively coupled plasma mass spectroscopy (ICP-MS). The relative distributions of arsenic species, the primary methylation index (PMI=MMAV/iAs) and the secondary methylation index (SMI=DMAV/MMAV) were calculated to assess the metabolism of arsenic. Subjects with skin lesions had a higher concentration of urinary arsenic and a lower arsenic methylation capability than subjects without skin lesions. Women had a significantly higher methylation capability of arsenic than men, as defined by a higher percent DMAV and SMI in urine among women, which was the one possible interpretation of women with a higher concentration of urinary arsenic but lower susceptibility to skin lesions. The findings suggested that not only the dose of arsenic exposure but also the arsenic methylation capability have an impact on the individual susceptibility to skin lesions induced by coal arsenic exposure.",
Arsenic,1343940,"Flavonoid dihydroquercetin, unlike quercetin, fails to inhibit expression of heat shock proteins under conditions of cellular stress Abstract: Modification by natural flavonoids quercetin and dihydroquercetin of the in vitro cell response to hyperthermal and chemical stress was studied. Quercetin completely inhibited the synthesis and intracellular accumulation of 70-kD heat shock protein (HSP70) in response to hyperthermia or to treatment with sodium arsenite, whereas dihydroquercetin in the same or higher doses had no such effect. Stress exposures under conditions of the quercetin-inhibited HSP70 expression significantly increased the percentage of dead and damaged cells compared to the same exposures in the absence of quercetin. On the contrary, dihydroquercetin virtually failed to increase the damage and death of the stress-exposed cells which displayed typical induction of HSP70. The findings suggest a new strategy for pharmacological use of these flavonoids with similar structure.",
Arsenic,1031548,"Cancer and occupational exposure to arsenic: A study of pesticide workers Abstract: Mortality and morbidity experience was studied in 1,393 persons exposed to considerably high air concentrations of inorganic arsenicals for varying lengths of time during the manufacture and packaging of various pesticides in a plant in Baltimore, Maryland. Study subjects were traced for the period 1946–1977, and vital status was determined for 86.9% of 1,050 men and 66.8% of 343 women. The observed numbers of deaths from all and selected causes were compared with the expected numbers of deaths derived from population mortality rates. Among men, 23 deaths from lung cancer and 2 deaths from anemias represented statistically significant excesses over the expected numbers (P < 0.05). Lung cancer mortality was especially high in male production workers with presumed high exposure to arsenicals for a prolonged period of time. A dose-response effect was suggested for lung cancer mortality which increased with length of arsenical exposure, but no such relationship appeared for nonarsenical exposure. Workers with high arsenical exposure also had increased frequencies of such forms of arsenism as keratoses and perforation of the nasal septum. Analysis of the 23 male lung cancer deaths and 23 matched controls suggested a relationship, though not statistically significant, between lung cancer and antecedent keratoses. These findings provide strong evidence for a causal relationship between occupational exposure to inorganic arsenicals and lung cancer.",
Arsenic,1349275,"The feasibility of epidemiologic studies of waterborne arsenic: A mortality study in Millard County, Utah Abstract: The current maximum contaminant level for arsenic in drinking water for the United States is 50 micrograms/liters (mu g/L). To provide suort for a reevaluation of the standard, a retrospective cohort mortality study is being conducted in several Utah communities. The available literature about the health effects of arsenic leaves some questions unresolved, including whether results from non-U.S. populations are generalizable to the United States. Previous analyses have concluded that it is not possible to conduct a human health effects study of waterborne arsenic in the United States because the number of persons exposed to moderate-to-high levels of waterborne arsenic was assumed to be relatively small. This paper, however, describes a population in Utah that historically has been exposed to moderate-to-high levels of arsenic ol er a long period of time. Also, the paper discusses how many of the obstacles to a U.S. study can be overcome. The study population has good characterization of exposure to drinking-water arsenic, residential stability, a minimum number of confounding factors, documented residence history with additional information on exposure, and cause-of-death information. Exposure data are described from water quality records, water rights records, local health departments, and geologic records. Given this relatively large cohort of exposed persons and a good assessment of exposure, the authors believe that it is feasible to conduct an epidemiologic study of waterborne arsenic exposure in a U.S. population.",
Arsenic,656873,"Hormesis and precaution: the twain shall meet Abstract: Regulatory focus on quantifying risk of disease or death from exposure to hazardous substances via monotonic dose-response models has downplayed or even rejected potential benefits to human health from exposures to low (sub-threshold) doses, and thus represented by either U-shaped or I-shaped models. On the other hand, most environmental health policy hypothesizes, without firm evidence, that cancer risk is proportional to exposure at low doses of current ambient exposures. An acceptable exposure is determined by either setting a somewhat arbitrary 'acceptable' level of risk, such as one in a million excess individual lifetime cancer risk or, in the case of several types of animal toxicological test results, applying multiplicative safety factors to a specific concentration, generally derived from a benchmark dose or NOAEL. This seemingly precautionary approach is questionable in light of much experimental evidence indicating protective effects of exposure at low doses - U-shaped or J-shaped models. We demonstrate that incorporating the possibility of hormesis into regulatory decision-making is precautionary, while use of default results in policy conflicts with precaution.",
Arsenic,710994,"Neuroprotective effect of curcumin in arsenic-induced neurotoxicity in rats Abstract: Our recent studies have shown that arsenic-induced neurobehavioral toxicity is protected by curcumin by modulating oxidative stress and dopaminergic functions in rats. In addition, the neuroprotective effect of curcumin has been investigated on arsenic-induced alterations in biogenic amines, their metabolites and nitric oxide (NO), which play an important role in neurotransmission process. Decrease in the levels of dopamine (DA, 28%), norepinephrine (NE, 54%), epinephrine (EPN, 46%), serotonin (5-HT, 44%), 3,4-dihydroxyphenylacetic acid (DOPAC, 20%) and homovanillic acid (HVA, 31%) in corpus striatum; DA (51%), NE (22%), EPN (47%), 5-HT (25%), DOPAC (34%) and HVA (41%) in frontal cortex and DA (35%), NE (35%), EPN (29%), 5-HT (54%), DOPAC (37%) and HVA (46%) in hippocampus, observed in arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) treated rats exhibited a trend of recovery in rats simultaneously treated with arsenic and curcumin (100 mg/kg body weight, p.o., 28 days). Increased levels of NO in corpus striatum (2.4-fold), frontal cortex (6.1-fold) and hippocampus (6.2-fold) in arsenic-treated rats were found decreased in rats simultaneously treated with arsenic and curcumin. It is evident that curcumin modulates levels of brain biogenic amines and NO in arsenic-exposed rats and these results further strengthen its neuroprotective efficacy.",
Arsenic,656661,"Health burden of skin lesions at low arsenic exposure through groundwater in Pakistan. Is river the source? Abstract: A significant proportion of groundwater in south Asia is contaminated with arsenic. Pakistan has low levels of arsenic in groundwater compared with China, Bangladesh and India. A representative multi-stage cluster survey conducted among 3874 persons >= 15 years of age to determine the prevalence of arsenic skin lesions, its relation with arsenic levels and cumulative arsenic dose in drinking water in a rural district (population: 1.82 million) in Pakistan. Spot-urine arsenic levels were compared among individuals with and without arsenic skin lesions. In addition, the relation of age, body mass index, smoking status with arsenic skin lesions was determined. The geographical distribution of the skin lesions and arsenic-contaminated wells in the district were ascertained using global positioning system. The total arsenic, inorganic and organic forms, in water and spot-urine samples were determined by atomic absorption spectrophotometry. The prevalence of skin lesions of arsenic was estimated for complex survey design, using surveyfreq and surveylogistic options of SAS 9.1 software. The prevalence of definitive cases i.e. hyperkeratosis of both palms and soles, was 3.4 per 1000 and suspected cases i.e. any sign of arsenic skin lesions (melanosis and/or keratosis), were 13.0 per 1000 among >= 15-year-old persons in the district. Cumulative arsenic exposure (dose) was calculated from levels of arsenic in water and duration of use of current drinking water source. Prevalence of skin lesions increases with cumulative arsenic exposure (dose) in drinking water and arsenic levels in urine. Skin lesions were 2.5-fold among individuals with BMI < 18.5 kg/m(2). Geographically, more arsenic-contaminated wells and skin lesions were alongside Indus River, suggests a strong link between arsenic contamination of groundwater with proximity to river. This is the first reported epidemiological and clinical evidence of arsenic skin lesions due to groundwater in Pakistan. Further investigations and focal mitigation measures for arsenic may be carried out alongside Indus River. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,2337091,"Characterization of acid mine drainage sources in the Iberian Pyrite Belt: Base methodology for quantifying affected areas and for environmental management Abstract: The present work aims to propose a methodology for quantifying the sources of acid mine drainage (AMD) and to characterize the magnitude of the affected areas in the Iberian Pyrite Belt (SW Spain). Such an approach allows the creation of a support tool for managing land and natural resources valorization, which may be easily applied in similar mining regions. The motivation and usefulness of this work can be realized by focusing on two main emerging strategic issues: (1) water resources management, with the example of Alcolea dam that will receive water from affected areas in the Iberian Pyrite Belt; and (2) mineral resources valorization, especially, regarding copper exploration due to increasing market prices. The used methodology included the following general steps: it started with an inventory of the mines in the Iberian Pyrite Belt, followed by field cartography campaigns and finally the quantification of affected areas and contaminant discharges. The results of the present work serve to confirm and quantify the magnitude of the AMD pollution in the Pyrite Belt. A total affected area of about 4,847 ha was estimated. Taking into account this figure and combining it with the annual average precipitation (650 L/m(2)) results in an estimation of 31,503,680 m(3)/year of discharging water affected by the presence of sulphides. In this scenario, a total annual contribution of 260,056 tonnes/year was obtained for sulphates, which means more than 712 tonnes a day. In the case of arsenic, a toxic element, the total annual contribution is more than 20 tonnes, or close to 55 kg/day. Regarding copper, this economically interesting metal translates into total contributions of 10,364 tonnes/year in the generating medium. This gave more than 28 tonnes/day, which today sits at 8,200 dollars/tonne. This result suggests that solutions aimed at recovering this resource should be searched. It may represent a financial return at the same time that it would mean overcome environmental liabilities.",
Arsenic,844,"Lung cancer findings from the NIOSH study of United States cadmium recovery workers: A cautionary note Abstract: This brief article was designed to highlight two problems regarding the quality of job history data and estimates of cadmium (7440439) exposure used in previous studies on lung cancer mortality among workers from the Globe cadmium recovery factory. The first problem concerned inconsistencies in the definition of the NIOSH job history data. The second problem concerned the accuracy of the NIOSH job history data collected. Information from personnel and service records had been used to classify periods of employment into different cadmium exposure categories. Detailed information on job history was available from time sheets, but was not used in previous studies. Detailed job history data may be important in adjusting for any effect of arsenic (7440382) exposure. A comparison of time sheet job history data for April through August 1949 with general work categories for the same time period as found in the NIOSH database indicated that worker exposures had been misclassified. The current authors note that much more accurate job history data from time sheets is available which should be incorporated into future studies.",
Arsenic,1255654,"Effects of arsenic on growth and photosystem II (PSII) activity of Microcystis aeruginosa Abstract: Effects of arsenic on growth, pigments content, oxygen evolution and photosystem II (PSII) activity of Microcystis aeruginosa were investigated in the present study. Various concentrations of As(III) did not show significant effects on growth and total carotenoids content within 24h of treatment. After 48h of treatment, 10mgL(-1) As(III) significantly inhibited the growth and synthesis of carotenoids of M. aeruginosa, while As(III) at concentrations ranging from 0 to 1mgL(-1) showed no significant inhibition. Chlorophyll a synthesis, oxygen evolution and chlorophyll fluorescence were more sensitive to As(III) exposure than carotenoid synthesis and growth. Chlorophyll a content, fast fluorescence rise transients and fluorescence decay kinetics appeared to be affected after the cells were exposed to 1 and 10mgL(-1) As(III) for more than 24h. Treatment with 10mgL(-1) As(III) for 24h or longer led to flattening of the fluorescence transient and drastic decrease of amplitude of fast phase of Q(A)(-) reoxidation kinetics. Exposure to As(III) mainly inhibited the quantum yield for primary photochemistry, density of reaction centers and photosynthesis performance index, and increased the dissipated energy. The decrease in amplitude of the fast and middle phases further revealed that once electron transfer from Q(A)(-) to Q(B) was inhibited by As(III), more Q(A)(-) was reoxidized via S(2)(Q(A)Q(B))(-) charge recombination. As(III) stress may result in an increased stability of the S(2)QB(-) and S(2)QA(-) recombination.",
Arsenic,1255499,"Toxic element concentrations in the bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba) and Risso's (Grampus griseus) dolphins stranded in eastern Adriatic Sea Abstract: Concentrations of cadmium (Cd), arsenic (As), mercury (Hg) and lead (Pb) were measured in muscle, liver and kidney of three cetacean species, the bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba) and Risso's (Grampus griseus) dolphins from the Croatian waters of the Adriatic Sea. In all three dolphin species Cd levels decreased in tissues in the order: kidney &gt; liver &gt; muscle, while As and Pb decreased in the order: liver &gt; kidney &gt; muscle for striped and Risso's dolphins, but with the order reversed for liver and kidney in the bottlenose dolphin for Pb. Levels of Hg consistently followed the order: liver &gt; muscle &gt; kidney, with mean concentrations in the liver being 11-34 times higher than in the other tissues. The highest mean concentrations of trace elements were measured in Risso's dolphins at 14.9 ?g/g wet weight, for Cd in the kidney, and concentrations in the liver of 2.41, 1,115 and 0.63 ?g/g for As, Hg and Pb, respectively. Statistically significant differences between the three dolphin species were determined for Cd, Hg and Pb in liver tissues, for As in muscle and for Cd in kidney. Significant correlations of metals between tissues were determined in all three species. The results presented give an indication of the environmental condition with regard to the content of toxic metals along the eastern coast of the Adriatic Sea.",
Arsenic,1070441,"Groundwater quality and its health impact: An assessment of dental fluorosis in rural inhabitants of the Main Ethiopian Rift Abstract: This study aims to assess the link between fluoride content in groundwater and its impact on dental health in rural communities of the Ethiopian Rift. A total of 148 water samples were collected from two drainage basins within the Main Ethiopian Rift (MER). In the Ziway-Shala basin in particular, wells had high fluoride levels (mean: 9.4±10.5mg/L; range: 1.1 to 68mg/L), with 48 of 50 exceeding the WHO drinking water guideline limit of 1.5mg/L. Total average daily intake of fluoride from drinking groundwater (calculated per weight unit) was also found to be six times higher than the No-Observed-Adverse-Effects-Level (NOAEL) value of 0.06mg/kg/day. The highest fluoride levels were found in highly-alkaline (pH of 7 to 8.9) groundwater characterized by high salinity; high concentrations of sodium (Na(+)), bicarbonate (HCO(3)(-)), and silica (SiO(2)); and low concentrations of calcium (Ca(2+)). A progressive Ca(2+) decrease along the groundwater flow path is associated with an increase of fluoride in the groundwater. The groundwater quality problem is also coupled with the presence of other toxic elements, such as arsenic (As) and uranium (U). The health impact of fluoride was evaluated based on clinical examination of dental fluorosis (DF) among local residents using the Thylstrup and Fejerskov index (TFI). In total, 200 rural inhabitants between the ages of 7 and 40years old using water from 12 wells of fluoride range of 7.8-18mg/L were examined. Signs of DF (TF score of ?1) were observed in all individuals. Most of the teeth (52%) recorded TF scores of 5 and 6, followed by TF scores of 3 and 4 (30%), and 8.4% had TF scores of 7 or higher. Sixty percent of the teeth exhibited loss of the outermost enamel. Within the range of fluoride contents, we did not find any correlation between fluoride content and DF. Finally, preliminary data suggest that milk intake has contributed to reducing the severity of DF. The study highlights the apparent positive role of milk on DF, and emphasizes the importance of nutrition in management efforts to mitigate DF in the MER and other parts of the world.",
Arsenic,1356907,"Lack Of Inhibition By Melatonin Of The Toxic And Proliferative Effects Of Dietary Dimethylarsinic Acid On Rat Urothelium Abstract: Arsenic is a known human carcinogen of the skin, lung, bladder, and possibly other internal organs. Dimethylarsinic acid (DMA), a major organic metabolite of arsenic in most mammals including humans, has been shown to be a bladder carcinogen in rats when administered in the diet or in the drinking water. Oxidative stress has been suggested as a mechanism for DMA-induced carcinogenesis. Our recent results suggest that the induction of cytotoxicity with necrosis and consequent regenerative proliferation of the urothelium may be involved in the process of DMA-induced urinary bladder carcinogenesis. Dimethylarsinous acid (DMAIII) generated from reduction of DMA, probably contributes to the process. To determine whether an antioxidant, melatonin, could inhibit the cytotoxic and proliferative effects of DMA, female F344 rats were concurrently treated with 1000 ppm melatonin and 100 ppm DMA in the diet. Histopathology, bromodeoxyuridine (BrdU) immunohistochemistry and scanning electron microscopy (SEM) were used to evaluate proliferative and cytotoxic changes in the urothelium. Melatonin did not show significant inhibitory effects on urothelial proliferation when compared with DMA alone. The BrdU labeling index was significantly increased in the DMA-treated rats with or without melatonin and by light microscopy there was no difference between the DMA and the DMA plus melatonin groups. However, there was the suggestion of a slight protective effect against DMA-induced cytotoxicity based on SEM observations. These results show that melatonin had little inhibitory effect on DMA-induced urinary bladder toxicity or proliferation in the rat. In addition, melatonin (0.2 mM) did not inhibit DMA (0.6 mM) or DMAIII (0.4 ?M)- induced cytotoxicity in vitro",
Arsenic,1023927,"Arsenite induces a cell stress-response gene, RTP801, through reactive oxygen species and transcription factors Elk-1 and CCAAT/enhancer-binding protein Abstract: RTP801 is a newly discovered stress-response gene that is induced by hypoxia and other cell stress signals. Arsenic is a heavy metal that is linked to carcinogenesis in humans. Here, we investigated the mechanism by which arsenic induces RTP801 transcription. In HaCaT human keratinocytes, arsenite was able to induce a rapid rise in the RTP801 mRNA level. Correspondingly, arsenite treatment was capable of stimulating a 2.5 kb human RTP801 promoter. Such a stimulatory effect was inhibited by co-expression of superoxide dismutase or glutathione peroxidase, and was abrogated by N-acetylcysteine, implying that ROS (reactive oxygen species) were involved in transcriptional regulation of the RTP801 gene. A series of deletion studies with the promoter revealed a critical arsenic-responsive region between -1057 and -981 bp of the promoter. Point mutations of the putative Elk-1 site and the C/EBP (CCAAT/enhancer-binding protein) site within this region were able to reduce the stimulatory effect of arsenite, indicating that Elk-1 and C/EBP are involved in transcriptional regulation of the RTP801 gene by arsenite. Furthermore, a gel mobility-shift assay demonstrated that arsenite was able to mount the rapid formation of a protein complex that bound the arsenic-responsive region as well as the C/EBP-containing sequence. The arsenite stimulation on RTP801 transcription was partly mediated by the ERK (extracellular-signal-regulated kinase) pathway, since the effect of RTP801 was inhibited by a selective ERK inhibitor. In addition, overexpression of Elk-1 and C/EBPbeta was able to elevate the promoter activity. Therefore these studies indicate that RTP801 is a transcriptional target of arsenic in human keratinocytes, and that arsenic and ROS production are linked to Elk-1 and C/EBP in the transcriptional control.",
Arsenic,1033731,"Development of thermotolerance in hsp70 induction-defective mutant of NRK cells Abstract: We investigated the relation between the synthesis of inducible form of heat-shock protein 70 (hsp70) and the development of thermotolerance using NRK (normal rat kidney) cells and their mutant cell line (39-1 cells). In NRK cells, hsp70 was clearly induced by conditioning treatments (42 degrees C for 2 h, 45 degrees C for 15 min or 100 microM sodium arsenite for 1 h). On the other hand, the induction of hsp70 in 39-1 cells was very low or not detectable by these treatments. Other high molecular weight hsps, hsc70 (constitutive form), hsp90 and hsp110 were induced in both cell lines. However, thermotolerance as defined by clonogenic survival was induced in both cell lines to a similar extent by the conditioning treatments. When cells were made thermotolerant by conditioning heating at 45 degrees C for 15 min, the inhibition of protein synthesis after challenge (second) heating was less in NRK cells than in 39-1 cells. This indicated that the extent of 'translational thermotolerance' was much higher in NRK cells than in 39-1 cells. From these results, it is suggested that the synthesis of inducible hsp70 is involved in the translational thermotolerance rather than the development of thermotolerance as defined by clonogenic survival.",
Arsenic,1339362,"Evaluation of an arsenic test kit for rapid well screening in Bangladesh Abstract: Exposure to arsenic in groundwater via drinking remains unabated for millions of villagers in Bangladesh. Since a blanket testing campaign using test kits almost a decade ago, millions of new wells have been installed but not tested; thus affordable testing is needed. The performance of the Arsenic Econo-Quick (EQ) kit was evaluated by blindly testing 123 wells in Bangladesh and comparing with laboratory measurements; 65 wells were tested twice. A subset of the same 123 wells was also tested using the Hach EZ kit in the field and the Digital Arsenator in the laboratory in Bangladesh. The EQ kit correctly determined the status of 110 (89%) and 113 (92%) out of 123 wells relative to the WHO guideline (10 ?g/L) and the Bangladesh standard (50 ?g/L), respectively. Relative to the WHO guideline, all misclassifications were underestimates for wells containing between &gt;10 and 27 ?g/L As. Relative to the Bangladesh As standard, over- and underestimates were evenly distributed. Given its short reaction time of 10 min relative to the Hach EZ and its lower cost compared to the Arsenator, the EQ kit appears to have several advantages for well testing in Bangladesh and elsewhere.",
Arsenic,627982,"Essential roles of PI-3K/Akt/IKKbeta/NFkappaB pathway in cyclin D1 induction by arsenite in JB6 Cl41 cells Abstract: Skin is a major target of carcinogenic trivalent arsenic (arsenite, As3+). It has been thought that cell proliferation is one of the central events involved in the carcinogenic effect of arsenite. Cyclin D1, a nuclear protein playing a pivotal role in cell proliferation and cell cycle transition from G1 to S phases, has been reported to be induced in human fibroblast by arsenite via uncertain molecular mechanisms. In the present study, the potential roles of PI-3K/Akt/IKKbeta/NFkappaB signal pathway in cyclin D1 induction by arsenite were addressed in mouse epidermal Cl41 cells. We found that exposure of Cl41 cells to arsenite was able to induce cell proliferation, activate PI-3K-->Akt/p70(S6k) signal pathway and increase cyclin D1 expression at both transcription and protein levels. Pre-treatment of Cl41 cells with PI-3K inhibitor, wortmannin, significantly inhibited the phosphorylation of Akt and p70(S6k) and thereby dramatically impaired the cyclin D1 induction by arsenite, implicating the importance of the PI-3K signal pathway in the cyclin D1 induction by arsenite. Furthermore, inhibition of PI-3K/Akt by overexpression of Deltap85 or DN-Akt blocked arsenite-induced IKK phosphorylation, IkappaBalpha degradation and cyclin D1 expression, indicating that IKK/NFkappaB is the downstream transducer of arsenite-triggered PI-3K/Akt cascade. Moreover, inhibition of IKKbeta/NFkappaB signal pathway by overexpression of its dominant negative mutant, IKKbeta-KM, also significantly blocked arsenite-induced cyclin D1 expression. Overall, arsenite exposure triggered PI-3K/Akt/IKKbeta/NFkappaB signal cascade which in turn plays essential roles in inducing cyclin D1 expression.",
Arsenic,627875,"Evaluation of immunotoxic and immunodisruptive effects of inorganic arsenite on human monocytes/macrophages Abstract: A trivalent inorganic arsenic, arsenite, has been causing chronic inflammation in humans through the consumption of contaminated well water. The total peripheral blood arsenic concentrations of chronic arsenic-exposed patients, who had inflammatory-like immune responses, are less than 1 AM, thus, nM concentrations may be very important regarding the chronic inflammatory effects by arsenite. However, there are few reports about the biological effects of low concentrations of arsenite in mammalian cells, especially in normal immune effector cells. In this study, we examined whether arsenite has any biological and/or toxicological effects on the differentiation of human peripheral blood monocytes into macrophages using the colonystimulating factor (CSF) in vitro compared with that of other metallic compounds, and found that arsenite sensitively inhibited the CSF-induced in vitro maturation of monocytes into macrophages at nM levels, and it also induced small, nonadhesive and CD14-positive abnormal macrophage generation from monocytes with granulocyte-macrophage CSF (GM-CSF) at 50–500 nM without cell death. The addition of other metallic compounds, including chromium, selenium, mercury, cadmium, nickel, copper, zinc, cobalt, manganese and other human pentavalent arsenic metabolites, such as inorganic arsenate, monomethylarsonic acid and dimethylarsinic acid, could not induce the same abnormal cell generation from monocytes with CSFs at any concentration and any additional time schedules; they showed only simple cytolethality in monocytes and macrophages at n-mM levels accompanied by cell death. This work may have implications in the arsenic-induced chronic inflammation in humans.",
Arsenic,1337365,"Retting of jute grown in arsenic contaminated area and consequent arsenic pollution in surface water bodies Abstract: Arsenic (As) toxicity of ground water in Bengal delta is a major environmental catastrophe. Cultivation of jute, a non edible crop after summer rice usually reduces arsenic load of the soil. However, during retting of jute As is present in the crop and thus increase its amount in surface water bodies. To test this hypothesis, a study was carried out in ten farmers' field located in As affected areas of West Bengal, India. As content of soil and variou the jute plant were recorded on 35 and 70days after sowing (DAS) as well as on harvest date (110DAS). During the study period, due to the influence of rainfall, As content of surface (0-150mm) soil fluctuates in a narrow range. As content of jute root was in the range of 1.13 to 9.36mgkg(-1). As content of both root and leaf attained highest concentration on 35DAS and continuously decreased with the increase in crop age. However, in case of shoot, the As content initially decreased by 16 to 50% during 35 to 70DAS and on 110DAS the value slightly increased over 70DAS. Retting of jute in pond water increased the water As content by 0.2 to 2.0mgL(-1). The increment was 1.1 to 4 times higher over the WHO safe limit (0.05mgL(-1)) for India and Bangladesh. Microbiological assessment in this study reveals the total bacterial population of pre and post retting pond water. Bacterial strains capable in transforming more toxic As-III to less toxic AS-V were screened and six of them were selected based on their As tolerance capacity. Importantly, identified bacterial strain Bacterium C-TJ19 (HQ834294) has As transforming ability as well as pectinolytic activity, which improves fibre quality of jute.",
Arsenic,628661,"Gene damage induced in human alveolar type II (L-132) cells by exposure to dimethylarsinic acid Abstract: To analyze the mechanisms of arsenic-induced gene damage, found previously in lungs of mice and rats orally administered dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenics, we employed an in vitro system using human alveolar type II (L-132) cells. The exposure to 10mM DMAA for 10 hr caused significant single-strand breaks in DNA of the cells. At an earlier period of the exposure, the replicative DNA synthesis was markedly suppressed, and the chain length of the nascent DNA was shorter than that of the control, suggesting that the template DNA received some modification other than strand breaks. The modification, being repairable, was sensitive to ultraviolet irradiation to cause strand breaks. These results suggest the possibility of DNA-adduct formation at the early period of DMAA exposure in L- 132 cells.",
Arsenic,711035,"Spatial patterns of fetal loss and infant death in an arsenic-affected area in Bangladesh Abstract: Arsenic exposure in pregnancy is associated with adverse pregnancy outcome and infant mortality. Knowledge of the spatial characteristics of the outcomes and their possible link to arsenic exposure are important for planning effective mitigation activities. The aim of this study was to identify spatial and spatiotemporal clustering of fetal loss and infant death, and spatial relationships between high and low clusters of fetal loss and infant death rates and high and low clusters of arsenic concentrations in tube-well water used for drinking.<br /><br /> Pregnant women from Matlab, Bangladesh, who used tube-well water for drinking while pregnant between 1991 and 2000, were included in this study. In total 29,134 pregnancies were identified. A spatial scan test was used to identify unique non-random spatial and spatiotemporal clusters of fetal loss and infant death using a retrospective spatial and spatiotemporal permutation and Poisson probability models.<br /><br /> Two significant clusters of fetal loss and infant death were identified and these clusters remained stable after adjustment for covariates. One cluster of higher rates of fetal loss and infant death was in the vicinity of the Meghna River, and the other cluster of lower rates was in the center of Matlab. The average concentration of arsenic in the water differed between these clusters (319 ?g/L for the high cluster and 174 ?g/L for the low cluster). The spatial patterns of arsenic concentrations in tube-well water were found to be linked with the adverse pregnancy outcome clusters. In the spatiotemporal analysis, only one high fetal loss and infant death cluster was identified in the same high cluster area obtained from purely spatial analysis. However, the cluster was no longer significant after adjustment for the covariates.<br /><br /> The finding of this study suggests that given the geographical variation in tube-well water contamination, higher fetal loss and infant deaths were observed in the areas of higher arsenic concentrations in groundwater. This illustrates a possible link between arsenic contamination in tube-well water and adverse pregnancy outcome. Thus, these areas should be considered a priority in arsenic mitigation programs.",
Arsenic,1327507,"Mechanisms of arsenite-mediated decreases in benzo[k]fluoranthene-induced human cytochrome P4501A1 levels in HepG2 cells Abstract: Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are often environmental cocontaminants that could interact to alter PAH carcinogenicity. The heavy metal, arsenite, and the PAH, benzo[k]fluoranthene, were used as prototypes to investigate, in human HepG2 cells, mechanisms whereby the bioactivation of benzo[k]fluoranthene by human CYP1A1 could be diminished by arsenite-mediated decreases in CYP1A1 induction by benzo[k]fluoranthene. To determine whether arsenite down-regulates CYP1A1 transcription, quantitative real-time reverse transcriptase-polymerase chain reaction assays and luciferase reporter gene expression assays were used with HepG2 cells treated with benzo[k]fluoranthene and arsenite, separately and as a mixture. Benzo[k]fluoranthene (0.5 microM) and arsenite (5 microM) markedly decreased benzo[k]fluoranthene-mediated induction of CYP1A1 mRNA by 45%. Plasmids containing the CYP1A1 promoter region (pHu-1A1-FL) were induced 7.4-fold over vehicle by benzo[k]fluoranthene (0.5 microM), whereas arsenite (1, 2.5, or 5 microM) decreased reporter gene expression by 46%, 45%, and 61%, respectively. The plasmid, pHu-1A1-Delta100-FL, lacked xenobiotic response element (XRE) sites at -1061 and -981 and showed greater responsiveness relative to pHu-1A1-FL, by 1.7-fold. Benzo[k]fluoranthene (0.5 microM) and arsenite (1, 2.5, or 5 microM) decreased reporter gene expression by 0%, 27%, and 39%, respectively, relative to expression levels produced by benzo[k]fluoranthene alone. Arsenite is stable for at least 48 h in the HepG2 cell medium with respect to its ability to diminish CYP1A1 benzo[k]fluoranthene induction. Arsenite did not affect benzo[k]fluoranthene induction directly through XRE sites, nor did it affect the stability of CYP1A1 mRNA. Thus, arsenite affects the transcriptional regulation of the benzo[k]fluoranthene-mediated induction of CYP1A1 and could diminish PAH carcinogenicity by decreasing bioactivation by CYP1A1.",
Arsenic,1350534,"Online monitoring of BALB/3T3 metabolism and adhesion with multiparametric chip-based system Abstract: A multiparametric chip-based system was employed to measure cell adhesion, metabolism, and response to metal compounds previously classified as cytotoxic in immortalized mouse fibroblasts (BALB/3T3 cell line). The system measures in parallel, online, and in label-free conditions the extracellular acidification rates (with pH-sensitive field effect transistors [ISFETs]), the cellular oxygen consumption (with amperometric electrode structures [Clark-type sensors]), and cell adhesion (with impedimetric interdigitated electrode structures [IDESs]). The experimental protocol was optimized to monitor metabolism and adhesion of the BALB/3T3 cell line. A total of 70,000 cells and a bicarbonate buffer-free running low-glucose Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal clone serum III and 1mM Hepes were selected to maintain cells in good conditions on the chip during the measurements performed under perfusion conditions. Cells were exposed to sodium arsenite, cadmium chloride, and cis-platinum at concentrations ranging from 1 to 100 microM. The kinetics of cell response to these compounds was analyzed and suggests that the Clark-type sensors can be more sensitive than IDESs and ISFETs in detecting the presence of high chemical concentration when short exposure times (i.e., 2h) are considered. The cytotoxicity data obtained from the online measurements of acidification, respiration, and adhesion at 24h compare well, in terms of half-inhibition concentration values (IC(50)), with the ones obtained using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and colony-forming efficiency (CFE) assay. The results show a good sensitivity of the system combined with the advantages of the online and label-free detection methods that allow following cell status before, during, and after the treatment in the same experiment.",
Arsenic,627249,"Critical roles of AMP-activated protein kinase in the carcinogenic metal-induced expression of VEGF and HIF-1 proteins in DU145 prostate carcinoma Abstract: Epidemiological and experimental animal data indicate that exposure to both metals and metalloid species exacerbates the risk of human diseases, particularly cancers. Vascular endothelial growth factor (VEGF), which performs a primary function in both tumor progression and angiogenesis, is up-regulated due to exposure to an array of carcinogenic metals, but the mechanisms responsible for the metal activation remain somewhat poorly understood. Recently, we demonstrated that AMP-activated protein kinase (AMPK), which acts as an energy sensor, providing metabolic adaptation effects under ATP-deprived conditions, is critical for the expression of VEGF under oxygen- and glucose-deprived conditions. As carcinogenic metals are potent VEGF expression inducers, we hypothesized that AMPK would also play a crucial role in metal-induced VEGF expression. Here, we present evidence that carcinogenic metals such as arsenite, vanadate, and cobalt, induce AMPK activation and VEGF expression via several different mechanisms, and that AMPK is able to regulate the expression of VEGF mRNA in a hypoxia-inducible factor-1-dependent or -independent manner, depending on the metal applied. We also attempted to characterize the relevant signal transduction pathways in metal-induced VEGF expression and AMPK activation, as well as the role of reactive oxygen species within this context. Overall, our data suggest that AMPK is a critical regulatory component in metal-induced VEGF expression, which further implies its intrinsic involvement in metal-induced carcinogenesis.",
Arsenic,627373,"Arsenic induces NAD(P)H-quinone oxidoreductase I by disrupting the Nrf2 x Keap1 x Cul3 complex and recruiting Nrf2 x Maf to the antioxidant response element enhancer Abstract: The ubiquitous toxic metalloid arsenic elicits pleiotropic adverse and adaptive responses in mammalian species. The biological targets of arsenic are largely unknown at present. We analyzed the signaling pathway for induction of detoxification gene NAD(P)H-quinone oxidoreductase (Nqo1) by arsenic. Genetic and biochemical evidence revealed that induction required cap 'n' collar basic leucine zipper transcription factor Nrf2 and the antioxidant response element (ARE) of Nqo1. Arsenic stabilized Nrf2 protein, extending the t(1/2) of Nrf2 from 21 to 200 min by inhibiting the Keap1 x Cul3-dependent ubiquitination and proteasomal turnover of Nrf2. Arsenic markedly inhibited the ubiquitination of Nrf2 but did not disrupt the Nrf2 x Keap1 x Cul3 association in the cytoplasm. In the nucleus, arsenic, but not phenolic antioxidant tert-butylhydroquinone, dissociated Nrf2 from Keap1 and Cul3 followed by dimerization of Nrf2 with a Maf protein (Maf G/Maf K). Chromatin immunoprecipitation demonstrated that Nrf2 and Maf associated with the endogenous Nqo1 ARE enhancer constitutively. Arsenic substantially increased the ARE occupancy by Nrf2 and Maf. In addition, Keap1 was shown to be ubiquitinated in the cytoplasm and deubiquitinated in the nucleus in the presence of arsenic without changing the protein level, implicating nuclear-cytoplasmic recycling of Keap1. Our data reveal that arsenic activates the Nrf2/Keap1 signaling pathway through a distinct mechanism from that by antioxidants and suggest an ""on-switch"" model of Nqo1 transcription in which the binding of Nrf2 x Maf to ARE controls both the basal and inducible expression of Nqo1.",
Arsenic,1677574,"Outcomes in Patients With Relapsed or Refractory Acute Promyelocytic Leukemia Treated With or Without Autologous or Allogeneic Hematopoietic Stem Cell Transplantation Abstract: BACKGROUND: Outcomes in patients with acute promyelocytic leukemia (APL) have improved; however, a significant number of patients still relapse despite receiving all-trans-retinoic acid (ATRA) and arsenic-based therapies. PATIENTS AND METHODS: Outcomes of patients with relapsed APL who were treated at our institution (1980-2010) and who received HCT were compared with those who received chemotherapy (CT) only. RESULTS: Among 40 patients, 24 received HCT (autologous [auto] HCT, 7; allogeneic [allo] HCT, 14; both, 3); 16 received CT only. The median age at diagnosis was 36 years (range, 13-50 years), 31 years (range, 16-58 years), and 44 years (range, 24-79 years) for the auto-HCT, allo-HCT, and CT groups, respectively. Ten (100%) patients who received auto-HCT and 12 (71%) who received allo-HCT were in complete remission at the time of the HCT. The median follow-ups in the auto-HCT, allo-HCT, and CT groups were 74 months (range, 26-135 months), 118 months (range, 28-284 months), and 122 months (range, 32-216 months), respectively. Transplantation-related mortality (1 year) after auto-HCT and allo-HCT were 10% and 29%, respectively. The 7-year event-free survival after auto-HCT and allo-HCT was 68.6% and 40.6%, respectively (P = .45). The 7-year overall survival was 85.7%, 49.4%, and 40% in the auto-HCT, allo-HCT, and CT groups, respectively (P = .48). CONCLUSION: Both auto-HCT and allo-HCT are associated with durable remission and prolonged survival. All 3 strategies (auto-HCT, allo-HCT, CT) were found to be feasible in the relapsed APL setting and result in long-term disease control in selected patients. In this retrospective analysis, overall survival for patients who received HCT was not significantly better than patients who received CT only, but a trend toward better outcomes was seen in patients who underwent auto-HCT, although not statistically significant.",
Arsenic,1028355,The arsenic limit tests of the British Pharmacopoeia Abstract: ,
Arsenic,1579381,The Conserved SKN-1/Nrf2 Stress Response Pathway Regulates Synaptic Function in Caenorhabditis elegans Abstract: ,
Arsenic,1453818,"Arsenic trioxide exerts antitumor activity through regulatory T cell depletion mediated by oxidative stress in a murine model of colon cancer Abstract: Immunotherapy is a promising antitumor strategy that can successfully be combined with current anticancer treatment. In this study, arsenic trioxide (As(2)O(3)) was shown to increase the antitumor immune response in CT26 colon tumor-bearing mice through the modulation of regulatory T cell (T(reg)) numbers. As(2)O(3) induced T(reg)-selective depletion in vitro. In vivo, tumor-bearing mice injected with 1 mg/kg As(2)O(3) showed a significant decrease in the T(reg)/CD4 cell ratio and in absolute T(reg) count versus controls. As(2)O(3) exerted antitumor effects only in immunocompetent mice and enhanced adoptive immunotherapy effects. Inhibition of As(2)O(3)-induced T(reg) depletion by the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester and the superoxide dismutase mimic manganese [III] tetrakis-(5, 10, 15, 20)-benzoic acid porphyrin suggested that it was mediated by oxidative and nitrosative stress. The differential effect of As(2)O(3) on T(reg) versus other CD4 cells may be related to differences in the cells' redox status, as indicated by significant differences in 2'7'dichlorodihydrofluorescein diacetate and 4,5-diaminofluorescein diacetate fluorescence levels. In conclusion, these results show for the first time, to our knowledge, that low doses As(2)O(3) can delay solid tumor growth by depleting T(regs) through oxidative and nitrosative bursts, and suggest that As(2)O(3) could be used to enhance the antitumor activity of adoptive immunotherapy strategies in human cancer.",
Arsenic,628050,"Arsenic and selenium in human hair: a comparison of five countries with and without arsenicosis Abstract: The selenium (Se) content of the diet and/or selenium supplements might have an ameliorating effect on arsenic (As) toxicity as recently shown by Wang et al., Yang et al., and as reviewed by Spallholz et al.. The underlying principles of the ameliorating effect is the complexation of Se with As forming the seleno-bis (S-glutathionyl) arsinium ion excreted in bile and the complexation of Se with As in tissues forming nontoxic insoluble selenides. Additional protection afforded by Se supplementation from arsenicosis could be the elevation of glutathione peroxidase activity reducing the oxidative stress induced by As. The present study assessed the status of Se and As in hair by neutron activation analysis (NAA). Human hair samples were collected from the United States, Canada, The People's Republic of China (PRC), Bangladesh, and Nepal, the latter two countries now engaged in a struggle to find relief from human arsenicosis resulting from extensive domestic groundwater contamination by As. No statistically significant differences were observed in the samples between the Se and As content of hair from, Lubbock, Texas (USA) or Winnipeg, Canada. The concentration of As in all hair samples analyzed correlated (r = 0.960, p < 0.001) with the amount of As in the drinking water. Selenium levels in hair were highest from Nepal. The results demonstrate the viability of hair as a noninvasive biomonitor in assessing aspects of dietary Se and environmental As exposure. The hair data confirmed the known low intake of Se in the Keshan disease area of the PRC, the very high accumulation in hair of As from subjects consuming contaminated groundwaters, and an adequate Se status in subjects from North America consuming municipal water of low As content. The high As content of hair from people in Bangladesh is the result of a high As consumption from contaminated water compounded by a less than desirable intake of Se. From Nepal, the As content of hair corresponded to the known low and high intake of As from contaminated groundwater. The very high Se content found in all hair samples from Nepal might be the result of the use of henna.",
Arsenic,1241791,"Arsenic Pollution in the Groundwater of Simav Plain, Turkey: Its Impact on Water Quality and Human Health Abstract: In this research, geological and hydrogeological studies were conducted to determine the source of high arsenic levels in the surficial aquifer of Simav Plain, Kutahya, Turkey. One of the two aquifer systems isolated in the study area was a deep confined aquifer composed of fractured metamorphic rocks that supply hot geothermal fluid. The other one was an unconfined alluvial aquifer, which developed within the graben area as a result of sediment deposition from the highlands. This aquifer serves as the primary water resource within the plain. A water quality sampling campaign conducted in 27 wells drilled in the surficial aquifer has yielded an average arsenic concentration of 99.1kg/L with a maximum of 561.5kg/L. Rock and sediment samples supported the fact that local metamorphic rocks contained significant amounts of sulfur minerals where arsenic-containing lenses are present inside. It was also determined that a Cu-Pb-Zn mine was operated in the past in the same formation. Arsenic-containing wastes of this mine were deposited near the Simav district center in an uncontrolled manner. This mined formation had arsenic levels reaching to levels as high as 660mg/kg, which was found out to be the highest arsenic level in the area. Another potential arsenic source in the study area was the geothermal fluid that was used extensively in three geothermal fields with levels reaching to levels as high as 594kg/L. Uncontrolled discharges of waste geothermal fluid and overexploitation of groundwater were also found to contribute to arsenic pollution in surface/subsurface waters of the plain. Thus, natural sources and anthropogenic influences of arsenic were found to create high concentrations in local water reserves of the area and influence human health. Consequently, death statistics from the 1995 to 2005 period collected from the area has revealed increased rates of gastrointestinal cancers above Turkish average.",
Arsenic,736685,"Neurosensory effects of chronic exposure to arsenic via drinking water in Inner Mongolia: I. Signs, symptoms and pinprick testing Abstract: This study was designed to assess the effects of exposure to arsenic in drinking water on neurosensory function. A questionnaire including neurological signs and symptoms and a brief neurological exam consisting of pinprick testing of the arms and legs and knee-jerk test were administered to 321 residents of the Bamen region of Inner Mongolia, China. Arsenic in water was measured by hydride generation atomic fluorescence. Participants were divided into three exposure groups--low (non-detectible-20), medium (100-300) and high (400-700 microg/I) arsenic. Significant group differences were observed in pinprick scores for all four limbs. Results indicate that arsenic alters pinprick (pain) thresholds at well-water concentrations as low as 400 microg/l, well below the 1000 microg/l threshold for neurological effect specified by NRC (1999). Regression models suggest that a 50% increase in pinprick score is associated with a 71-159 ppb increase in arsenic concentration.",
Arsenic,1018912,"Oral administration of dimethylarsinic acid, a main metabolite of inorganic arsenic, in mice promotes skin tumorigenesis initiated by dimethylbenz(a)anthracene with or without ultraviolet B as a promoter Abstract: Concerning arsenic-induced tumorigenesis, an animal model must be developed for understanding the mechanism of human carcinogenesis by arsenics. To determine whether orally administered dimethylarsinic acid (DMA) promotes and causes the progression of skin tumorigenesis, an animal protocol by topical application of dimethylbenz(a)anthracene (DMBA) with or without UVB, a tumor promoter, in hairless mice was used. The administration of DMA by the oral route promoted not only the formation of papillomas induced by DMBA alone but also the formation of malignant tumors induced by way of the formation of atypical keratoses by treatment with DMBA and UVB. A phenomenon, the progression of keratoses--&gt;atypical keratoses--&gt;squamous cell carcinomas (SCCs), observed in the present study may resemble the development of tumors in arsenic-exposed humans. We also discussed the involvement of a reactive oxygen species (ROS), e.g., the dimethylarsenic peroxy radical [(CH3)2AsOO.], produced during the metabolic processing of DMA, in skin and in multi-organ tumorigenesis.",
Arsenic,1070396,"Nutritional manipulation of one-carbon metabolism: effects on arsenic methylation and toxicity Abstract: Exposure to arsenic (As) through drinking water is a substantial problem worldwide. The methylation of As, a reactive metalloid, generates monomethyl- (MMA) and dimethyl-arsenical (DMA) species. The biochemical pathway that catalyzes these reactions, one-carbon metabolism, is regulated by folate and other micronutrients. Arsenic methylation exerts a critical influence on both its urinary elimination and chemical reactivity. Mice having the As methyltransferase null genotype show reduced urinary As excretion, increased As retention, and severe systemic toxicity. The most toxic As metabolite in vitro is MMA(III), an intermediate in the generation of DMA(V), a much less toxic metabolite. These findings have raised the question of whether As methylation is a detoxification or bioactivation pathway. Results of population-based studies suggest that complete methylation of inorganic As to DMA is associated with reduced risk for As-induced health outcomes, and that nutrients involved in one-carbon metabolism, such as folate, can facilitate As methylation and elimination.",
Arsenic,627924,"Dietary arsenic intake in Taiwanese districts with elevated arsenic in drinking water Abstract: Inorganic arsenic in dietary staples (ie., yams and rice) may have substantially contributed to exposure and adverse health effects observed in an endemic Taiwanese population historically exposed to arsenic in drinking water. Observations of this population were used by the U.S. Environmental Protection Agency to derive toxicity values that form the basis for arsenic risk assessment and various regulations in the United States. However, data were previously insuffcient to accurately estimate dietary intake. Rice and yam samples collected in 1993 and 1995 from Taiwanese districts with endemic arsenic were analyzed for total arsenic and for inorganic and organic monoand dimethylarsenic. The acid digestion techniques used in the analyses are among the best to preserve organic arsenic in the test sample. Furthermore, concurrent analyses of the proportion of inorganic arsenic in split samples of rice and yams collected in the 1995 investigation were in good agreement, despite using a different digestion method. These data support a likely mean dietary intake of 50 ¡.g/day with a range of 15 to 2Il ¡.g/day. Consideration of dietary intake may result in a downward revision of the assumed potency of ingested arsenic as reflected in EPA's toxicity values.",
Arsenic,1453807,"Metals and trace element concentrations in breast milk of first time healthy mothers: a biological monitoring study Abstract: ABSTRACT: BACKGROUND: Breast milk is the best source of nutrition for the newborn infant. However, since all infants cannot be breast-fed, there is a need for background data for setting adequate daily intakes. Previously, concentration data on major essential elements and some toxic elements in breast milk, based on different analytical techniques, have been published. There is no recent study on a large number of metals and trace elements in breast milk, using a sensitive analytical method for determination of low element concentrations. METHODS: Breast milk concentrations of 32 metals and elements in early lactation (days 14--21) were determined in a random sample of first time Swedish mothers (n = 60) using inductively coupled plasma mass spectrometry (ICPMS). RESULTS: There were small inter-individual concentration variations in the macroelements Ca, K, Mg, P and S, and striking similarities across studies and over time, supporting a tight regulation of these elements in breast milk. Large inter-individual and over time differences were detected for Na concentrations, which may reflect an increase in salt consumption in Swedish women. Large inter-individual differences were also detected for the microelements Co, Cr, Mn and Mo, and the toxic metals As, Cd, Pb, Sb and V. Arsenic and B were positively correlated with fish consumption, indicating influence of maternal intake on breast milk concentrations. Observed differences in breast milk element concentrations across studies and over time could be attributed to the timing of sampling and a general decline over time of lactation (Cu, Fe, Mo, Zn), a possible lack of regulation of certain elements in breast milk (As, B, Co, Mn, Se) and time trends in environmental exposure (Pb), or in some cases to differences in analytical performance (Cr, Fe). CONCLUSIONS: This study provides reliable updated information on a number of metals and elements in breast milk, of which some have not previously been reported.",
Arsenic,2343459,"Heavy metal accumulation in balsam pear and cowpea related to the geochemical factors of variable-charge soils in the Pearl River Delta, South China Abstract: Variable-charge (v-c) soils in subtropical areas contain considerable amounts of iron/aluminum (Fe/Al) oxides that can strongly influence the fate of heavy metals in agricultural ecosystems. However, the relationship between heavy metal accumulation in vegetables and the geochemical factors associated with v-c soils in subtropical regions remains unknown. The present study investigated heavy metal accumulation under field conditions in the Pearl River Delta (PRD) by measuring the content of 8 heavy metals (zinc (Zn), arsenic (As), copper (Cu), mercury (Hg), lead (Pb), chromium (Cr), nickel (Ni) and cadmium (Cd)) in 43 pairs of v-c soil and vegetable (balsam pear and cowpea) samples. Soil physicochemical properties including pH, texture, organic matter and oxide minerals (Fe2O3, SiO2, Al2O3, CaO, MgO, K2O and Na2O) were also analyzed. Heavy metal accumulation from soil to vegetables was assessed based on bioconcentration factors (BCFs). The results showed that soil extractable Fe, oxide minerals and chemical weathering indices of v-c soils strongly affected heavy metal accumulation, whereas the content of Zn, Cu, Cr and Ni in vegetables was strongly affected by the soil clay content. Significant correlations were found between the BCFs of heavy metals and oxide minerals. However, no significant relationship was found between pH and heavy metal accumulation (except for Cu) in balsam pear and cowpea. Correlation analyses showed that a lower oxalate/DCB- extractable Fe content might indicate greater heavy metal (Zn, Cu, Hg, Cr and Ni) accumulation in vegetables. Therefore, it can be deduced that oxalate/DCB- extractable Fe content is a critical geochemical factor that determines the bioavailability of heavy metals and that iron biogeochemical cycles play vital roles in the fate of heavy metals in vegetable fields in this area. These findings provide new insights into the behaviors and fate of heavy metals in subtropical v-c soils and can be used to develop possible guidelines for vegetable safety management.",
Arsenic,627720,"Mechanism of erythrocyte death in human population exposed to arsenic through drinking water Abstract: Arsenic contamination in drinking water is one of the biggest natural calamities, which has become an imperative threat to human health throughout the world. Abbreviation of erythrocyte lifespan leading to the development of anemia is a common sequel in arsenic exposed population. This study was undertaken to explore the mechanism of cell death in human erythrocytes during chronic arsenic exposure. Results revealed transformation of smooth discoid red cells into evaginated echinocytic form in the exposed individuals. Further distortion converted reversible echinocytes to irreversible spheroechinocytes. Arsenic toxicity increased membrane microviscosity along with an elevation of cholesterol/phospholipid ratio, which hampered the flexibility of red cell membrane and made them less deformable. Significant increase in the binding of merocyanine 540 with erythrocyte membrane due to arsenic exposure indicated disruption of lipid packing in the outer leaflet of the cell membrane resulting from altered transbilayer phospholipid asymmetry. Arsenic induced eryptosis was characterized by cell shrinkage and exposure of phosphatidylserine at the cell surface. Furthermore, metabolic starvation with depletion of cellular ATP triggered apoptotic removal of erythrocytes from circulation. Significant decrease in reduced glutathione content indicating defective antioxidant capacity was coupled with enhancement of malondialdehyde and protein carbonyl levels, which pointed to oxidative damage to erythrocyte membrane. Arsenic toxicity intervened into red cell membrane integrity eventually leading to membrane destabilization and hemoglobin release. The study depicted the involvement of both erythrophagocytosis and hemolysis in the destruction of human erythrocytes during chronic arsenic exposure.",
Arsenic,2278384,"Daily bioaccessible levels of selected essential but toxic heavy metals from the consumption of non-dietary food sources Abstract: Researchers and regulatory bodies tend to focus on non-essential toxic elements when testing for inorganic chemical pollutants in food. Both toxic and essential elements are increasingly getting into the food chain from the extensive use agrochemicals and the use of contaminated water, raw sewage and untreated industrial effluent to irrigate crops. A holistic testing protocol for chemical contaminants in food should be the norm in order to protect human health, especially considering that the essential elements are as a matter of fact essential poisons. They are essential but are toxic above certain thresholds. Eating contaminated foods that are not considered to be dietary sources of the essential poisons may result in an inadvertent overdose, especially considering that consumers may be taking food supplements that recommended as sources of the essential elements. We measured the levels of manganese and zinc in rice and calculated the daily bioaccessible levels of the two elements. The daily bioaccessible levels were significantly higher than the recommended daily intakes in most of the samples. It has to be noted that exposure from various sources is additive, therefore, lower levels than recommended limits in one source may not guarantee safety from a particular chemical toxicant. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,1797834,"Synthesis and onwards coordination of an As(I) centered zwitterion Abstract: The bis(phosphino)borate ligand class is used as an anionic anchor to stabilize reactive, low coordinate arsenic centers. The neutral, zwitterionic As(I) species, 2, is formed very cleanly, and isolated in good yields using cyclohexene as a halogen scavenger. The uniqueness of this heterocyclic As(I) compound is on display with the coordination to Group?6 metal centers, (2?M(CO)5 ; M=Cr, Mo, W). The arsenic?metal bond lengths are longer than the related AsPh3 complexes suggesting that compound 2 is a weak sigma donor. The metal complexes reveal a trigonal pyramidal arsenic atom, which provides the first experimental evidence for the presence of two &quot;lone pairs&quot; of electrons on the As(I) center. When more flexible and more electron-donating isopropyl substituents were used, an intermediate (compound 5) in the formation of low coordinate pnictogen compounds was crystallographically characterized. This structure, formally a base-stabilized dichloroarsenium cation, provides an alternative mechanistic proposal to the one described in the literature.",
Arsenic,2215712,"Total and inorganic arsenic in foods of the first Hong Kong total diet study Abstract: Arsenic (As) is a metalloid that occurs in different inorganic and organic forms, which are found in the environment both from natural occurrence and from anthropogenic activity. The inorganic forms of As are more toxic as compared to the organic As, but so far most of the occurrence data in food collected in the framework of official food control are still reported as total As without differentiating the various arsenic species. In this paper, total As and inorganic arsenic (iAs) contents of 600 total diet study (TDS) samples, sub-divided into 15 different food groups, were quantified by high resolution inductively coupled plasma mass spectrometry (HR-ICP/MS) and hydride generation (HG) ICP/MS respectively. The method detection limits for both total As and iAs were 3 ?g As kg-1. As the samples were prepared for TDS, food items were purchased directly from the market or prepared as for normal consumption, i.e. table-ready, in the manner most representative of and consistent with cultural habits in Hong Kong as far as practicable. The highest total As and iAs content were found in fish, seafood and their products and vegetables and their products respectively. Besides, this paper also presents the ratios of iAs and total As content in different ready-to-eat food items. The highest ratio of iAs to total As was found in vegetables and their products. It is likely that iAs in vegetables maintained its status even after cooking.",
Arsenic,2278989,"Postoperative imaging of bioabsorbable anchors in rotator cuff repair Abstract: <strong>BACKGROUND: </strong>Bioabsorbable anchors may lead to osteolysis and cyst formation. However, the prevalence of these outcomes is not known for rotator cuff repairs.<br /><br /><strong>PURPOSE: </strong>To evaluate cyst formation after placement of bioabsorbable anchors for rotator cuff repairs and to verify whether bioabsorbable anchors degraded as intended and preserved bone stock for possible revision compared with metal anchors. The null hypothesis was that the rate and severity of cyst formation around the anchor are negligible.<br /><br /><strong>STUDY DESIGN: </strong>Case series; Level of evidence, 4.<br /><br /><strong>METHODS: </strong>Between April 2008 and November 2011, a total of 209 patients (85 men, 124 women) underwent rotator cuff repair with bioabsorbable suture anchors (113 with polylactic acid enantiomers [PLLA] and 96 with poly-D,L-lactide from L-lactide and D-lactide [PLDLA]); the patients underwent magnetic resonance imaging (MRI) evaluation more than 10 months after surgery. The fluid signal around the anchor on T2-weighted MRI scans was graded as follows: grade 0, no fluid around anchor; grade 1, minimal fluid around anchor; grade 2, local fluid around anchor; grade 3, fluid collection around entire length of anchor with cyst diameter less than twice the anchor diameter; and grade 4, cyst diameter larger than grade 3. The integrity of repairs was also evaluated.<br /><br /><strong>RESULTS: </strong>Cysts were observed in 97 instances (46.4%). There were 41 grade 1 cases (19.6%), 16 grade 2 (7.7%), 22 grade 3 (10.5%), and 18 grade 4 (8.6%). Healing of repaired tendon was observed in 131 patients (62.7%). There was no statistical difference in healing rate between patients with and without cyst formation (66.1% vs 58.8%; P = .276). Altered anchor shape and absorption were not observed in most of the patients. However, in 12 patients (6 with PLLA and 6 with PLDLA anchors), T2-weighted scans showed that the signal intensity of anchors had changed since surgery, which could indicate that absorption had taken place; nonetheless, even in these 12 patients, anchors were clearly visible on T1-weighted scans.<br /><br /><strong>CONCLUSION: </strong>Osteolysis and cyst formation are common complications following the use of bioabsorbable anchors in rotator cuff repairs. Considering that adequate absorption of anchors and preservation of bone stock are the reasons for using bioabsorbable anchors, use of these anchors should be reconsidered because of possible interference with revision surgery.",
Arsenic,1026400,"The use of 'exotic' framework structures in waste management Abstract: The use of porous framework materials in waste management applications has the potential to be a powerful tool in toxic metal remediation. The properties that these materials possess, including high surface area and ion-exchange capacity, are theoretically valuable. Furthermore, the flexibility of many of these frameworks allows the potential for immobilisation of waste materials with the framework of the material, in addition to the traditional capture in the pore structure. However, for either of these routes to be useful for waste management purposes, these structures must also be stable in any proposed storage media. This study examines the stability of a range of porous materials whose frameworks are made out of zinc and arsenic, both considered toxic minesite wastes, when exposed to aqueous media. The three frameworks examined (sodalite analogue Na(6)(H(2)O)(8)(ZnAsO(4))(6), open framework K(3)Zn(4)O(AsO(4))(3).3.5H(2)O, and an ABW type framework NH(4)ZnAsO(4)) all have similar hydrothermal synthetic routes and bulk framework compositions, but differ in counter ion used, pore size and complexity of structure. The phases were examined before and after storage in an aqueous environment, and their crystallinity and leaching were determined. All phases prepared were found to be extremely unstable outside their original synthetic environment, and very soluble when exposed to water, calling into question their practical use in any environment.",
Arsenic,2278043,"Assessing vanadium and arsenic exposure of people living near a petrochemical complex with two-stage dispersion models Abstract: The goal of this study is to demonstrate that it is possible to construct a two-stage dispersion model empirically for the purpose of estimating air pollution levels in the vicinity of petrochemical plants. We studied oil refineries and coal-fired power plants in the No. 6 Naphtha Cracking Complex, an area of 2,603-ha situated on the central west coast of Taiwan. The pollutants targeted were vanadium (V) from oil refineries and arsenic (As) from coal-fired power plants. We applied a backward fitting method to determine emission rates of V and As, with 192 PM10 filters originally collected between 2009 and 2012. Our first-stage model estimated emission rates of V and As (median and 95% confidence intervals at 0.0202 (0.0040-0.1063) and 0.1368 (0.0398-0.4782) g/s, respectively. In our second stage model, the predicted zone-average concentrations showed a strong correlation with V, but a poor correlation with As. Our findings show that two-stage dispersion models are relatively precise for estimating V levels at residents' addresses near the petrochemical complex, but they did not work as well for As levels. In conclusion, our model-based approach can be widely used for modeling exposure to air pollution from industrial areas in countries with limited resources.",
Arsenic,1030591,"Developmental mechanisms of arsenite toxicity in zebrafish (Danio rerio) embryos Abstract: Arsenic usually accumulates in soil, water and airborne particles, from which it is taken up by various organisms. Exposure to arsenic through food and drinking water is a major public health problem affecting some countries. At present there are limited laboratory data on the effects of arsenic exposure on early embryonic development and the mechanisms behind its toxicity. In this study, we used zebrafish as a model system to investigate the effects of arsenite on early development. Zebrafish embryos were exposed to a range of sodium arsenite concentrations (0-10.0mM) between 4 and 120h post-fertilization (hpf). Survival and early development of the embryos were not obviously influenced by arsenite concentrations below 0.5mM. However, embryos exposed to higher concentrations (0.5-10.0mM) displayed reduced survival and abnormal development including delayed hatching, retarded growth and changed morphology. Alterations in neural development included weak tactile responses to light (2.0-5.0mM, 30hpf), malformation of the spinal cord and disordered motor axon projections (2.0mM, 48hpf). Abnormal cardiac function was observed as bradycardia (0.5-2.0mM, 60hpf) and altered ventricular shape (2.0mM, 48hpf). Furthermore, altered cell proliferation (2.0mM, 24hpf) and apoptosis status (2.0mM, 24 and 48hpf), as well as abnormal genomic DNA methylation patterning (2.0mM, 24 and 48hpf) were detected in the arsenite-treated embryos. All of these indicate a possible relationship between arsenic exposure and developmental failure in early embryogenesis. Our studies suggest that the negative effects of arsenic on vertebrate embryogenesis are substantial.",
Arsenic,1508609,"Evaluation and comparison of aluminum-coated pumice and zeolite in arsenic removal from water resources Abstract: In this research the potential of aluminum-coated pumice and zeolite in arsenic, As (V) removal was investigated and compared. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and X-Ray Flaorescence Spectrometry (XRF) were carried out to determine the properties of the adsorbents. Several parameters including adsorbent dosage] pH, contact time, and initial As(V) concentration were studied. The optimum pH obtained for both adsorbents was pH?=?7. As(V) adsorption by both adsorbents followed the Freundlich isotherm (for aluminum-coated pumice and zeolite respectively with R2?&gt;?0.98 and R2?&gt;?0.99). The obtained data from kinetics showed that the pseudo-second order model could better explain As(V) adsorption for both aluminum-coated pumice and zeolite (R2?&gt;?0.98 and R2?&gt;?0.99 respectively). Because of low cost, both adsorbents may be economically used, but aluminum-coated zeolite showed high efficiency of, due to its porosity and surface area. More than 96% of As(V) with initial concentration of 250 ?g/L was removed by 10 g/L aluminum-coated zeolite at pH?=?7 and in 60 minutes to achieve As(V) concentration of 10 ?g/L, while only 71% of As(V) could be removed by aluminum-coated pumice.",
Arsenic,2149256,"SCREENING OF AS-ACCUMULATING PLANTS USING A FOLIAR APPLICATION AND A NATIVE ACCUMULATION OF AS Abstract: The discovery of novel accumulating plants is useful for efficient phytoremediation due to the demands of various conditions of impacted sites such as land use, soil properties, concentration of pollutants, and climate. In the present study, we investigated foliar application or a field with highly bioavailable arsenic (As) to screen As-accumulating plants. Plants grown in the downstream of a hot springs area were analyzed for native As accumulation and As foliar application, and the rhizosphere soils were collected. The water-soluble As in the rhizosphere soils had a high average, 144 microg/kg, whereas total As was similar to normal soil in Japan. Among 34 herbaceous plants and 17 woody plants, Chelidonium majus var. asiaticum accumulated a relatively high As level, 8.07 mg/kg DW (93.6% of As added), that was not revealed by native accumulation. In a further pot experiment, C. majus accumulated a moderately high As level (314 mg/kg DW) in the roots but not in the shoot (30.1 mg/kg DW), and exhibited a low transfer factor (TF = 0.096). Thus, a foliar application would be a simple and high-throughput method to screen plants that accumulate and tolerate As. C. majus would be useful as a tool for phytostabilization of As.",
Arsenic,2088554,"Soil biological attributes in arsenic-contaminated gold mining sites after revegetation Abstract: Recovery of arsenic contaminated areas is a challenge society faces throughout the world. Revegetation associated with microbial activity can play an essential role in this process. This work investigated biological attributes in a gold mining area with different arsenic contents at different sites under two types of extant revegetation associated with cover layers of the soil: BS, Brachiaria sp. and Stizolobium sp., and LEGS, Acacia crassicarpa, A. holosericea, A. mangium, Sesbania virgata, Albizia lebbeck and Pseudosamanea guachapele. References were also evaluated, comprising the following three sites: B1, weathered sulfide substrate without revegetation; BM, barren material after gold extraction and PRNH (private reserve of natural heritage), an uncontaminated forest site near the mining area. The organic and microbial biomass carbon contents and substrate-induced respiration rates for these sites from highest to lowest were: PRNH &gt; LEGS &gt; BS &gt; B1 and BM. These attributes were negatively correlated with soluble and total arsenic concentration in the soil. The sites that have undergone revegetation (LEGS and BS) had higher densities of bacteria, fungi, phosphate solubilizers and ammonium oxidizers than the sites without vegetation. Principal component analysis showed that the LEGS site grouped with PRNH, indicating that the use of leguminous species associated with an uncontaminated soil cover layer contributed to the improvement of the biological attributes. With the exception of acid phosphatase, all the biological attributes were indicators of soil recovery, particularly the following: microbial carbon, substrate-induced respiration, density of culturable bacteria, fungi and actinobacteria, phosphate solubilizers and metabolic quotient.",
Arsenic,627127,"Arsenic induced blood and brain oxidative stress and its response to some thiol chelators in rats Abstract: Chronic arsenic toxicity is a widespread problem, not only in India and Bangladesh but also in various other regions of the world. Exposure to arsenic may occur from natural or industrial sources. The treatment that is in use at present employs administration of thiol chelators, such as meso 2,3-dimercaptosuccinic acid (DMSA) and sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), which facilitate its excretion from the body. However, these chelating agents are compromised with number of limitations due to their lipophobic nature, particularly for their use in cases of chronic poisoning. During chronic exposure, arsenic gains access into the cell and it becomes mandatory for a drug to cross cell membrane to chelate intracellular arsenic. To address this problem, analogs of DMSA having lipophilic character, were examined against chronic arsenic poisoning in experimental animals. In the present study, therapeutic efficacy of meso 2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), monoisoamyl DMSA (MiADMSA) were compared in terms of reducing arsenic burden, as well as recovery in the altered biochemical variables particularly suggestive of oxidative stress. Adult male Wistar rats were given 100-ppm arsenic for 10 weeks followed by chelation therapy with the above chelating agents at a dose of 50 mg/Kg (orally) once daily for 5 consecutive days. Arsenic exposure resulted in marked elevation in reactive oxygen species (ROS) in blood, inhibition of ALAD activity and depletion of GSH. These changes were accompanied by significant decline in blood hemoglobin level. MiADMSA was the most effective chelator in reducing ROS in red blood cells, and in restoring blood ALAD compared to two other chelators. Brain superoxide dismutase (SOD) and glutathione peroxidase (GPx) decreased, while ROS and TBARS increased significantly following arsenic exposure. There was a significant increase in the activity of glutathione-S-transferase (GST) with a corresponding decline in its substrate i.e. glutathione. Among all the three chelators, MiADMSA showed maximum reduction in the level of ROS in brain. Additionally, administration of MiADMSA was most effective in counteracting arsenic induced inhibition in brain ALAD, SOD and GPx activity. Based on these results and in particular higher metal decorporation from blood and brain, we suggest MiADMSA to be a potential drug of choice for the treatment of chronic arsenic poisoning. However, further studies are required for the choice of appropriate dose, duration of treatment and possible effects on other major organs.",1
Arsenic,1015845,"A sensitive and selective fluorescence sensor for the detection of arsenic(III) in organic media Abstract: Arsenic contamination is a leading environmental problem. As such, levels of this toxic metalloid must be constantly monitored by reliable and low-cost methodologies. Because the currently accepted upper limit for arsenic in water is 10 ppb, very sensitive and selective detection strategies must be developed. Herein we describe the synthesis and characterization of a fluorescent chemical probe, namely, ArsenoFluor1, which is the first example of a chemosensor for As(3+) detection in organic solvents at 298 K. AF1 exhibits a 25-fold fluorescence increase in the presence of As(3+) at ?(em) = 496 nm in THF, which is selective for As(3+) over other biologically relevant ions (such as Na(+), Mg(2+), Fe(2+), and Zn(2+)) and displays a sub-ppb detection limit.",
Arsenic,627782,"Polymerase chain reaction-based deletion analysis of spontaneous and arsenite-enhanced gpt mutants in CHO-AS52 cells Abstract: In this study, we have examined the mutagenicity of sodium arsenite at the xanthine-guanine phosphoribosyltransferase locus (ypt) in a pSV2 gpt-transformed CHO cell line, AS52. Our results provide very weak evidence for arsenite as a gene mutagen because the chemical at high doses and at high cytotoxicity enhances barely a doubling of mutant frequency (MF) and a doubling of the gpt gene deletion frequency compared to controls. We suggest that the increase in MF in arsenite-treated cells results from arsenic, as comutagen, enhancing the induction effect of any unknown endogenous or exogenous factors on the spontaneous mutagenesis of AS52 cells. Nested PCR analysis mutants has a total deletion of the gpt gene. For the spontaneous, 50 ?M arsenite- and 100 ?M arsenite-enhanced spontaneous mutants in AS52 cells, the percentages of total deletion of the gpt gene are 36.00%, 54.72% and 66.67%, respectively. We suggest that a high proportion of the gene deletion in arsenite-enhanced mutants may be due to the high cytotoxicity of the chemical.",
Arsenic,2279178,"Beat over the old ground with new strategy: Engineering As···As interaction in arsenite-based Dawson cluster ?-[W18O54(AsO3)2](6-) Abstract: By reaction of [As2W19O67(H2O)](14-), NiCl2·6H2O, and phen under hydrothermal conditions, a new organic-inorganic tungstoarsenate hybrid [Ni(phen)3]4[As2W18O60]{[Ni(phen)2][H2As2W18O60]}·12H2O (where phen = 1,10-phenanthroline) (1) was obtained via self-assembly and characterized by elemental analysis, infrared (IR) spectroscopy, solid UV-vis absorption spectrum, and single-crystal X-ray diffraction (XRD). An unprecedented 18-tungstoarsenate Dawson cluster, ?-[W18O54(AsO3)2](6-), encapsulating two pyramidal arsenite AsO3(3-) anions as templates and exhibiting interesting intramolecular As···As interaction is first achieved. 1 displays a one-dimensional (1D) chain architecture constructed by alternating ?-[W18O54(AsO3)2](6-) and nickel(II) complexes [Ni(phen)2)](2+). The resulting hybrid can act as a photocatalyst to prompt the degradation of Rhodamine B (RhB) with excellent efficiency.",
Arsenic,627477,"Role of keratinocyte-derived cytokines in chemical toxicity Abstract: Following appropriate stimulation, such as with tumor promoters, ultraviolet light or various chemical agents, keratinocytes synthesize and secrete cytokines which can mediate or participate in dermatotoxic responses such as inflammation, hyperkeratosis, hypersensitivity and skin cancer. We have determined the qualitative and quantitative cytokine response in primary human keratinocyte cultures following exposure to several non-sensitizing contact irritants, sensitizers and ulcerative agents as well as a skin carcinogen. The chemicals were also administered to mice to assess whether the dermatotoxic response correlated with the in vitro production of keratinocyte-derived cytokines. Due to the complex cellular interactions that occur in the skin, it was not possible to identify specific cytokine profiles for most of the classes of dermatotoxic agents studied. However, the non-sensitizing contact irritants produced relative increases in the synthesis and secretion of the proinflammatory cytokines, interleukin-1 and tumor necrosis factor-alpha, as well as the neutrophil chemotactic cytokine, interleukin-8 compared to the other chemical agents. While ulcerative compounds as well as irritants elicited neutrophils to the site of chemical application when applied to the mouse skin, time-dependent and chemical-specific patterns of inflammation were detected. Treatment of human keratinocyte cultures with arsenic, a human skin carcinogen, resulted in a unique cytokine profile characterized by induction of growth factors, including transforming growth factor-alpha and granulocyte-macrophage colony stimulating factor. Treatment of v-Ha-ras transgenic mice, an animal model for skin cancer, with arsenic caused an increase in the number of papillomas as well as overexpression of these growth factors suggesting that they participate in arsenic-induced skin papilloma development. These studies indicate a diverse role exists for keratinocyte-derived cytokines in dermatotoxic actions.",1
Arsenic,2149297,Vestigialization of arsenic resistance phenotypes/genotypes in Chromobacterium violaceum strains thriving in pristine Brazilian sites Abstract: ,
Arsenic,1519194,"Comparison of microwave assisted acid digestion methods for ICP-MS determination of total arsenic in fish tissue Abstract: Fish is one of the most important sources of arsenic exposure in human diet and the Food Safety and Quality Division, Ministry of Health since 2007 has required routine monitoring of total arsenic in seafoods such as fish. This study describes an improved extraction method of total arsenic in fish using microwave assisted acid digestion procedure before being analysed by inductively coupled plasma mass spectrometry (ICP-MS). The parameters studied were pre-treatment of sample, digestion temperature, time programme and the chemicals (HNO3/H2O2) used. Arsenic contents in fish samples under these conditions were compared using the standards additions technique. Microwave assisted acid digestion method with a combination of ultrapure concentrated nitric acid (HNO3) to concentrated hydrogen peroxide (H2O2) at a ratio of 7 mL: 1 mL, run time of 25 min and digestion temperature of 200°C with no pre-treatment was found to have recovery of 100.7% as compared with other digestion procedure where the recovery were 115.5, 111.6 and 101.8%. Validation using certified reference material (CRM) of fish tissue (DORM-3) showed a recovery of 101.4 ± 2.5% for total arsenic from the CRM.",
Arsenic,1936113,"Metals Concentrations in Sediments of Lakes and Wetlands in the Upper Columbia River Watershed: Lead, Zinc, Arsenic, Cadmium, Antimony, and Mercury Abstract: Sediments were collected from ten lakes and wetlands in the Upper Columbia River watershed of northeast Washington in 2012. Samples were analyzed for lead, zinc, arsenic, cadmium, copper, antimony, mercury, total organic carbon, and grain size. Lead-210 also was analyzed in a selected sediment core for age-dating and assessment of sedimentation rates. The current 2012 study builds upon findings from a broader areal investigation of northeast Washington lakes conducted in 2010. The 2010 study reported comparatively elevated metals concentrations in lake sediments from portions of the study area generally in the vicinity of the Upper Columbia River valley. Historical transboundary air pollution from the Trail smelter in British Columbia was identified in the 2010 study as the probable, predominant area-wide source of upland lakes sediment contamination (metals) in the vicinity of the Upper Columbia River valley. Spatial and temporal patterns in metals concentrations are described and the potential for adverse biological effects assessed. The chronology of metals deposition is illustrated with an age-dated sediment core collected from Cedar Lake near the international border with British Columbia, Canada. The history of smelter operations within this region is briefly reviewed as it pertains to the probable source(s) of contamination and observed sediment results. The 2012 findings are consistent with and refine the spatial metals concentration patterns identified in the 2010 study. For all the lakes and wetlands sampled by both studies, the findings document: 1. Higher concentrations of lead, zinc, arsenic, cadmium, antimony, and mercury occur in lake sediment from the western part of the northeast Washington study area (nearer the Upper Columbia River). 2. Sediment from lakes located closest to the Upper Columbia River valley shows an overall northward-increasing metals concentration trend, with highest concentrations typically observed in lakes located nearer to the international border. 3. Mercury appears to be dispersed more broadly, across the west and north-central portions of the study area, than is observed for lead, zinc, arsenic, cadmium, and antimony. Concentrations of lead and cadmium in sediments from selected northeast Washington lakes/wetlands pose a potential concern for adverse biological effects. This assessment is based on a comparison of measured metals concentrations to literature-based probable effects concentration thresholds for freshwater ecosystems. Data from this 2012 lake/wetland sediment study further demonstrate the need for additional investigation to more fully characterize the geographic extent of historical smelter emission metals enrichment associated with potential ecological concerns, including terrestrial soils associated with upland environments in the Upper Columbia River watershed.",
Arsenic,1017960,"Dynamic features of ecophysiological response of freshwater clam to arsenic revealed by BLM-based toxicological model Abstract: The objective of this study was to use a quantitative process-based damage assessment model (DAM) associated with biotic ligand model (BLM) to examine the ecophysiological responses of freshwater clam Corbicula fluminea to waterborne arsenic. We carried out a 14-day exposure experiment to obtain bioaccumulation parameters and a 7-day acute toxicity bioassay to obtain survival data. To investigate the survival dynamics, we examined 2 key parameters characterizing bioaccumulation and damage regulation: capacity to eliminate body arsenic burden and reversible ability to recover the damage. Results show that uptake rate constant of 2.075±0.442 (mean±SE) ml g-1 d-1 during uptake phase and elimination rate constant was estimated to be 0.1995±0.022 d-1. The derived bioconcentration factor of 10.401 ml g-1 suggests that arsenic has a high potential for bioaccumulation in C. fluminea. Our results show that a negative association between bioaccumulation and the fraction of arsenic binding in biotic ligand at 50% mortality, indicating that C. fluminea with higher arsenic binding in gill biotic ligand at 50% mortality level gives a lower capacity to accumulate bioavailable arsenic. We found a linearly positive correlation between elimination rate and recovery rate constants. Yet, a potential tradeoff between ability to eliminate arsenic and ability to recover the damage is not found. We showed that an ecophysiological significance of C. fluminea exposed to arsenic can be revealed by the elimination-recovery regime. This research may also provide mechanistic insights into the development of biomonitoring organism such as C. fluminea mimicking metal bioaccumulation in a real situation.",
Arsenic,1341103,"Inhibition of heme oxygenase-1 partially reverses the arsenite-mediated decrease of CYP1A1, CYP1A2, CYP3A23, and CYP3A2 catalytic activity in isolated rat hepatocytes Abstract: Heme oxygenase (HO-1), the rate-limiting enzyme in the physiological breakdown of heme, is ubiquitous, and its expression can be increased by arsenite [As(III)], and similar other stimuli that induce cellular oxidative stress. Interestingly, it has been shown that the As(III)-induced HO-1 is inversely correlated with a decrease in cytochromes P450 (P450s) activity; however, the direct role for HO-1 in the inhibition of P450 enzymes remains unknown. Our results showed that As(III) at a concentration of 5 ?M decreased the constitutive and inducible expression of CYP1A1, CYP1A2, CYP3A23, and CYP3A2 at the mRNA, protein, and catalytic activity levels. Moreover, As(III) decreased the nuclear accumulation of aryl hydrocarbon receptor (AhR) and pregnane X receptor without increasing their degradation. As(III) also increased the binding of cytosolic AhR to heat shock protein 90 and hepatitis B virus X-associated protein 2. In the presence of 2,3,7,8-tetrachlorodibenzo-p-dioxin as an inducer for CYP1A and rifampin as an inducer for CYP3A, As(III) decreased the enzymatic activity of the four P450s more than it decreased their mRNA or protein expression levels. It is noteworthy that treatment with the competitive HO-1 inhibitor, tin-mesoporphyrin, or supplementing external heme partially reversed the As(III)-mediated decrease in activities of the four P450s. In conclusion, the current study provides the first evidence that As(III) decreases CYP1A1, CYP1A2, CYP3A23, and CYP3A2 expression in freshly isolated rat primary hepatocytes. Furthermore, inhibiting the As(III)-mediated induction of HO-1 partially restores the enzymatic activity of these P450s that was initially decreased by As(III), confirming the direct role of HO-1 in the inhibition of P450s.",1
Arsenic,1019389,"Exposure to preservatives used in the industrial pre-treatment of timber Abstract: OBJECTIVE: The research was to survey potential dermal exposure and inhalation exposure of operators to preservative fluids used in industrial timber pre-treatment. RESULTS: Surveys in 1996-98 produced 64 data points. These were taken from 54 sites, and involved 57 timber pre-treatment process operators. Of the data, 38 related to copper chromium arsenic preservative used in vacuum-pressure processes, 19 to solvent-based preservative in double vacuum processes and 7 to water-based preservative in double vacuum processes. Treatment cycle times, preservative concentrations, treatment load sizes and quantities of preservative used per cubic metre of timber are reported. Preservative deposition patterns were similar for all treatments, with about 90% on the legs, and most of the remainder on the arms and chest. The results are quoted as mg preservative preparation (as opposed to active substance), expressed as mg per treatment cycle and mg per minute. Water-based products in vacuum-pressure processes (38 data) showed potential dermal exposure in the range 547-132,000 mg per cycle with a median value 3960 mg per cycle (median cycle time 3 h). Water-based products in double vacuum processes (7 data) showed a range 59-8750 mg per cycle with a median value 4260 mg per cycle; and solvent-based products in double vacuum processes (19 data) showed a range 7.5-449 mg per cycle with a median value 119 mg per cycle (median cycle time 1 h for double-vacuum processes). Contamination of work clothing occurred in nearly all surveys, with around 10% penetration of the preservative as estimated by a sampling patch mounted inside the operator's coveralls. Contamination was measured inside the operator's gloves in nearly all surveys. Wearing fresh gloves was found to reduce exposure to arsenic by 71% and to permethrin by 37%. Contamination on socks was measured and found to be less frequent for double vacuum than for vacuum-pressure processes. Exposure by inhalation for vacuum-pressure processes expressed as preservative, showed a range of 0.06-7.96 mg/m3, with a median value of 1.07 mg/m3, time-weighted average exposure over one or two treatment cycles. Exposure was detected in 68% of the vacuum-pressure process surveys. There was evidence for aerosol generation on transporting timber treated with water-based preservative. For double vacuum processes, two non-zero results only were found, both for water-based preservatives. Aerosols within treatment vessels were found to have dispersed 2.5 min after opening the door. Pilotstudy biological monitoring data for urinary chromium, arsenic, and permethrin metabolites are quoted with reference to creatinine. There are tentative conclusions relating to up take via the skin.",
Arsenic,1240146,"Accumulation and Transformation of Arsenic in the Blue-Green Alga Synechocysis sp. PCC6803 Abstract: Synechocysis sp. PCC6803 is a unicellular blue alga which ubiquitously exists in aquatic system and is considered to play a role in arsenic cycling. Our results showed that Synechocysis can accumulate arsenic as much as 1.0 and 0.9 gkg super(-1) DW when exposed to 0.5 mM arsenate and arsenite for 14 days, respectively. In addition, arsenic species in cells were assayed under different exposure conditions and it was found that inorganic arsenic, including arsenate and arsenite, is the dominant species. Organic methylated arsenicals can only be detected exposed to higher arsenic concentration range (100-500 mu M). Arsenate is the dominant arsenic species and presents more than 80% of the total arsenic in cells. Efflux of both arsenate and arsenite was observed. When treated with 2.67 mu M arsenite, Synechocysis can rapidly oxidize arsenite to arsenate and accumulate As rapidly. The observed arsenic oxidation in solute is solely caused by cellular oxidation. Given the robust ability of As accumulation, it can serve as a phytoremediation organism to efficiently remove arsenic from aquatic environments.",
Arsenic,2337274,"Geological factors controlling occurrence and distribution of arsenic in groundwaters from the southern margin of the Duero Basin, Spain Abstract: Groundwater from springs and boreholes on the southern edge of the Cenozoic Duero Basin (DB) of Spain has concentrations of arsenic (As) which are commonly above the EC drinking-water limit of 10 ?g/L and reach observed values up to 241 ?g/L. Groundwater compositions within the sedimentary aquifer vary from Ca-HCO3 type, variably affected by evaporation and agricultural pollution at shallow levels, to Na-HCO3 compositions in deeper boreholes of the basin. Groundwater conditions are mainly oxidising, but reducing groundwaters exist in sub-basins within the aquifer, localised flow paths likely being influenced by basement structure. Arsenic concentrations are spatially variable, reaching up to 38 ?g/L in springs of the Spanish Central System (SCS) basement aquifer and up to 62 ?g/L in springs from the DB. Highest As concentrations are associated with the Na-HCO3 compositions in deep boreholes (200-450 m depth) within the DB. These have high pH values (up to 9.6) which can give rise to associated elevated concentrations of V and U (up to 64 and 30 ?g/L, respectively). In the deep borehole waters of the DB, oxidising flows derived from the mineralised igneous-metamorphic basement and discharging via major faults, and are considered the origin of the higher concentrations. Compositions are consistent with desorption of As and other anionic species from metal oxyhydroxides in an oxic environment. Under locally reducing conditions prevalent in some low-flow parts of the DB, an absence of detectable dissolved As is coincident with low or undetectable SO4 concentrations, and consistent with loss via formation of authigenic sulphide minerals. Mitigation measures are needed urgently in this semi-arid region where provision of alternative sources of safe drinking water is logistically difficult and expensive.",
Arsenic,1015922,"A prospective study of arsenic exposure from drinking water and incidence of skin lesions in Bangladesh Abstract: Elevated concentrations of arsenic in groundwater pose a public health threat to millions of people worldwide. The authors aimed to evaluate the association between arsenic exposure and skin lesion incidence among participants in the Health Effects of Arsenic Longitudinal Study (HEALS). The analyses used data on 10,182 adults free of skin lesions at baseline through the third biennial follow-up of the cohort (2000-2009). Discrete-time hazard regression models were used to estimate hazard ratios and 95% confidence intervals for incident skin lesions. Multivariate-adjusted hazard ratios for incident skin lesions comparing 10.1-50.0, 50.1-100.0, 100.1-200.0, and ?200.1 ?g/L with ?10.0 ?g/L of well water arsenic exposure were 1.17 (95% confidence interval (CI): 0.92, 1.49), 1.69 (95% CI: 1.33, 2.14), 1.97 (95% CI: 1.58, 2.46), and 2.98 (95% CI: 2.40, 3.71), respectively (P(trend) = 0.0001). Results were similar for the other measures of arsenic exposure, and the increased risks remained unchanged with changes in exposure in recent years. Dose-dependent associations were more pronounced in females, but the incidence of skin lesions was greater in males and older individuals. Chronic arsenic exposure from drinking water was associated with increased incidence of skin lesions, even at low levels of arsenic exposure (&lt;100 ?g/L).",
Arsenic,2347642,"Isolation, identification and arsenic-resistance of Acidithiobacillus ferrooxidans HX3 producing schwertmannite Abstract: Schwertmannite, a ubiquitous mineral present in iron oxyhydroxides formed in iron- and sulfate-rich acid media, favors incorporation of some toxic anions in its structure. We reported an iron-oxidizing bacterial strain HX3 from a municipal sludge that facilitates the formation of pure schwertmannite in cultures. Ferrous iron oxidation by the isolated strain HX3 was optimum at an initial pH of 2.0-3.3 and temperature of 28-35°C. Pure schwertmannite was found through bacterial oxidation of ferrous iron at an initial pH2.8 and temperature 28°C. Following 16S rDNA gene sequence analysis the bacterial strain HX3 was identified as Acidithiobacillus ferrooxidans. The arsenic-resistance A. ferrooxidans HX3 showed the potential of environmental application in arsenic removal from the As(III)- and iron-rich acid sulfate waters directly by As(III) adsorption or the formation of schwertmannite in the environment.",
Arsenic,1346717,"Modelling some heavy metals air concentration in Europe Abstract: Metals, as well as other air toxic pollutants, can be responsible for a range of human health effects via inhalation or ingestion. European normatives regulate lead, arsenic, cadmium, mercury and nickel ambient air levels in order to prevent potential damage to human health and ecosystems; annual target levels of 500, 6, 5 and 20 ng/m(3) for Pb, As, Cd and Ni are set for these pollutants in directives 2008/50/CE and 2004/107/CE. Air quality models constitute a powerful tool to understand tropospheric dynamic and to assign concentration values to areas where no measurement is available. However, not many models include heavy metals in their code, and mainly results for Pb, Cd and Hg have been published. In this paper, we present preliminary results on modelling Pb, Cd, As, Ni, Cu, Zn, Cr and Se air background concentration in Europe using the CHIMERE model, at a 0.2A degrees resolution and the evaluation of the model performance in order to see its capability to reproduce observed levels. This evaluation was performed by comparing simulated values with observations at the EMEP monitoring sites, as only values at background sites can be captured at the 0.2A degrees model resolution. Important uncertainties mainly related to emissions should be solved in order to obtain an improvement of model performance; more recent annual totals, information on snap activities for each metal, higher spatial resolution and a better knowledge of the temporal emission behaviour is necessary to adequately model these air pollutants. Also a better treatment of these particles considering more realistic metal size distribution, more refined deposition processes or some chemical processes regarding Se could result in better model results. A larger number of stations and a better temporal coverage of observations are also important to carry out a better statistical analysis of model performance.",
Arsenic,67508,"Regional alterations in the levels of brain biogenic amines, glutamate, GABA, and GAD activity due to chronic consumption of inorganic arsenic in developing and adult rats Abstract: The effects of chronic exposure to arsenic (7440382) during development on biogenic amine neurotransmitters were studied. Wistar-rats were treated with 5mg/kg arsenic per day beginning 2 days after birth and continuing until 60 days of age. The brains were studied 20, 60, and 160 days after birth. The effects of arsenic on the brains of adult rats were studied by treating 90 day old animals with 5mg/kg arsenic daily for 90 days. Decreases in body weights, brain weights, and food intake were seen in developing and adult animals treated with arsenic compared with controls up through the latest time point studied. Decreases in the levels of noradrenaline (NA), dopamine (DA), and serotonin (5-HT) were seen, particularly in the cerebellum and hypothalamus, 60 days after arsenic treatment in developing rats. These changes persisted 100 days after discontinuing treatment. Changes in NA, DA, and 5-HT in the brainstem, cerebellum, and hippocampus were seen as well in the adult animals. Decreases in the activity of glutamic-acid-decarboxylase (GAD) and gamma-amino-butyric-acid (GABA) levels were seen in some areas of the brain in the developing group, however most of these returned to normal after cessation of arsenic treatment. In adult rats, an increase in glutamate levels were seen in the motor cortex, striatum, nucleus accumbens, and hippocampus. GABA levels were decreased in the striatum, cerebellum, and brainstem, and GAD activity was reduced in the nucleus accumbens, hippocampus, hypothalamus, and cerebellum.",
Arsenic,477028,"Effect of Centella asiatica on arsenic induced oxidative stress and metal distribution in rats Abstract: Concomitant oral supplementation of Centella asiatica (100, 200 or 300 mg kg(-1), orally once daily) during arsenic exposure (20 ppm in drinking water for 4 weeks) was investigated in rats for its protective value. The animals exposed to arsenic (III) showed a significant inhibition of delta-aminolevulinic acid dehydratase (ALAD) activity, a marginal decrease in glutathione (GSH) and an increase in zinc protoporphyrin (ZPP) level in blood. Hepatic and renal glutathione (GSH) decreased, while oxidized glutathione (GSSG) and thiobarbituric acid reactive substance (TBARS) levels increased significantly in the liver, kidney and brain. The activities of brain superoxide dismutase (SOD) and catalase decreased marginally on arsenic exposure. Concomitant administration of Centella asiatica showed a significant protective action on inhibited blood ALAD activity and restored the blood GSH level, whereas most of the other blood biochemical parameters remained unchanged on Centella asiatica supplementation. Interestingly, most of the hepatic biochemical variables indicative of oxidative stress showed protection. There was, however, a significant protection observed in the altered kidney GSSG level and hepatic and brain TBARS. Only a marginal beneficial effect of Centella asiatica on blood and liver arsenic concentration was noted, particularly at the highest dose studies (300 mg kg(-1)). No effect of Centella asiatica on most of the altered renal biochemical parameters was noted. The results thus lead to the conclusion that simultaneous supplementation of Centella asiatica significantly protects against arsenic-induced oxidative stress but does not influence the arsenic concentration in these organs. It can thus be suggested that co-administration of Centella asiatica protects animals from arsenic-induced oxidative stress but exhibits no chelating property. Further studies are recommended for determining the effect of co-administration of Centella asiatica during chelation therapy with a thiol chelator. Copyright (c) 2006 John Wiley & Sons, Ltd.",
Arsenic,1354405,Biooxidation of a gold-containing sulfide concentrate in relation to changes in physical and chemical conditions Abstract: ,
Arsenic,2141411,"Arsenic contamination in groundwater and its effects on adolescent intelligence and social competence in Bangladesh with special reference to daily drinking/cooking water intake Abstract: <strong>OBJECTIVE: </strong>The present study aims to investigate the relationship between arsenic (As) exposure and intelligence quotient (IQ) or social competence (SC) of Bangladeshi adolescents (aged 14 or 15 years) in Sonargaon thana.<br /><br /><strong>METHODS: </strong>Information about socioeconomic status (SES) was collected as confounding factors. To evaluate the relative contribution of As sources to total As intake, the As concentrations in urine and drinking/cooking water, and the amount of water added in cooking, were assessed on site using a food frequency questionnaire (FFQ).<br /><br /><strong>RESULTS: </strong>The results confirmed that As exposure was essential to lower adolescent IQ or SC because they were negatively associated with As exposure after controlling for SES (particularly household income). Except for cooking water, the amount of drinking water varied with season and appeared to be the major As source because the As concentration in water was generally correlated with the As concentration in urine, and they were related to lower IQ or SC (even after controlling for SES). The FFQ survey revealed that rice was consumed the most frequently (more than once daily), followed by daal (bean) soup and nonleafy vegetables, but fish, meat, and eggs were consumed approximately once a week. Water intake per meal from cooked rice was estimated to be 616 mL/person, followed by bean soup (258 mL/person) and cooked vegetables (82 mL/person).<br /><br /><strong>CONCLUSIONS: </strong>Our results suggest that water used for cooking might be an important source of As, and the cooking process can affect the amount of As in cooked food.",
Arsenic,1347245,"Differential temperature dependency of chemical stressors in HSF1-mediated stress response in mammalian cells Abstract: Expression of stress proteins is generally induced by a variety of stressors. To gain a better understanding of the sensing and induction mechanisms of stress responses, we studied the effects of culture temperature on responses to various stressors, since the induction of hsp70 in mammalian cells by heat shock is somehow modulated by culture temperature. Hsp70 was not induced by treatment with sodium arsenite, azetidine-2-carboxylic acid, or zinc sulfate at the level of heat shock factor (HSF) 1 activation in cells incubated at low temperature, although these treatments induced hsp70 in cells incubated at 37 degrees C. The repression of sodium arsenite or zinc sulfate-induced HSF1 activation by low temperature was not simply due to the inhibition of protein synthesis. On the other hand, heat shock and iodoacetamide induced HSF 1 activation in cells incubated at either temperature. Thus, there seem to be two kinds of stressors that induce HSF1 activation independently of or dependent on culture temperature. Furthermore, the reduction of glutathione level seemed to be essential for HSF1 activation by chemical stressors.",
Arsenic,2279380,"Confirmation of elevated arsenic levels in groundwater of Myanmar Abstract: Millions of villagers across South and Southeast Asia are exposed to toxic levels of arsenic (As) by drinking well water. In order to confirm the field-kit results that Myanmar is also affected, a total of 55 wells were tested in the field in January 2013 and sampled for laboratory analysis across seven villages spanning a range of As contamination in the lower Ayeyarwady basin. Elevated concentrations of As (50-630?g/L) were measured in wells up to 60m deep and associated with high levels of Fe (up to 21mg/L) and low concentrations of SO4 (&lt;0.05mg/L). Concentrations of As &lt;10?g/L were measured in some shallow (&lt;30m) grey sands and in both shallow and deep orange sands. These results indicate that the main mechanism of As release to groundwater in Myanmar is the reductive dissolution of Fe oxyhydroxides, as in the neighboring Bengal, Mekong, and Red River basins. Concentrations of As in groundwater of Myanmar are therefore unlikely to change rapidly over time and switching to existing low-As wells is a viable way of reducing exposure in the short term. However, only 17 of the 55 well owners interviewed correctly recalled the status of their well despite extensive testing in the region. A renewed effort is thus needed to test existing wells and new wells that continue to be installed and to communicate the health risks of exposure to As for infants, children, and adults.",
Arsenic,1017822,"Curcumin protects DNA damage in a chronically arsenic-exposed population of West Bengal Abstract: Groundwater arsenic contamination has been a health hazard for West Bengal, India. Oxidative stress to DNA is recognized as an underlying mechanism of arsenic carcinogenicity. A phytochemical, curcumin, from turmeric appears to be potent antioxidant and antimutagenic agent. DNA damage prevention with curcumin could be an effective strategy to combat arsenic toxicity. This field trial in Chakdah block of West Bengal evaluated the role of curcumin against the genotoxic effects of arsenic. DNA damage in human lymphocytes was assessed by comet assay and fluorescence-activated DNA unwinding assay. Curcumin was analyzed in blood by high performance liquid chromatography (HPLC). Arsenic induced oxidative stress and elucidation of the antagonistic role of curcumin was done by observation on reactive oxygen species (ROS) generation, lipid peroxidation and protein carbonyl. Antioxidant enzymes like catalase, superoxide dismutase, glutathione reductase, glutathioneS-transferase, glutathione peroxidase and non-enzymatic glutathione were also analyzed. The blood samples of the endemic regions showed severe DNA damage with increased levels of ROS and lipid peroxidation. The antioxidants were found with depleted activity. Three months curcumin intervention reduced the DNA damage, retarded ROS generation and lipid peroxidation and raised the level of antioxidant activity. Thus curcumin may have some protective role against the DNA damage caused by arsenic.",
Arsenic,1508657,"Trace elements in fish from Taihu Lake, China: Levels, associated risks, and trophic transfer Abstract: Concentrations of eight trace elements [iron (Fe), manganese (Mn), zinc (Zn), chromium (Cr), mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As)] were measured in a total of 198 samples covering 24 fish species collected from Taihu Lake, China, in September 2009. The trace elements were detected in all samples, and the total mean concentrations ranged from 18.2 to 215.8?g/gdw (dry weight). The concentrations of the trace elements followed the sequence of Zn&gt;Fe&gt;Mn&gt;Cr&gt;As&gt;Hg&gt;Pb&gt;Cd. The measured trace element concentrations in fish from Taihu Lake were similar to or lower than the reported values in fish around the world. The metal pollution index was used to compare the total trace element accumulation levels among various species. Toxabramis swinhonis (1.606) accumulated the highest level of the total trace elements, and Saurogobio dabryi (0.315) contained the lowest. The concentrations of human non-essential trace elements (Hg, Cd, Pb, and As) were lower than the allowable maximum levels in fish in China and the European Union. The relationships between the trace element concentrations and the ?(15)N values of fish species were used to investigate the trophic transfer potential of the trace elements. Of the trace elements, Hg might be biomagnified through the food chain in Taihu Lake if the significant level of p-value was set at 0.1. No biomagnification and biodilution were observed for other trace elements.",
Arsenic,1338824,"Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin Abstract: This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11100 and from 20 to 248mgAskg(-1) (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (&gt;0.1% d.w.) in Cladophora sp.",
Arsenic,1519212,"The effect of different types of anthropogenic changes in soils on communities of oribatids in urban ecosystems Abstract: Communities of oribatids that inhabit the soils of urban ecosystems that have various degree of pollution with heavy metals and arsenic, recreational loads, and surface transformation were studied. The suppressing effect of the anthropogenic pressures on the communities of oribatids was investigated. The effect of the recreational load, the increase in the density of soil composition and elimination of the sod horizon, as well as the formation of urbanozems on oribatids are comparable to the effects of pollution. Among oribatids, species that indicate a disturbed states of communities and the purity of ecosystems were found.",
Arsenic,2343542,"Combating Mineral Malnutrition through Iron and Zinc Biofortification of Cereals Abstract: Iron and zinc are 2 important nutrients in the human diet. Their deficiencies in humans lead to a variety of health-related problems. Iron and zinc biofortification of cereals is considered a cost-effective solution to overcome the malnutrition of these minerals. Biofortification aims at either increasing accumulation of these minerals in edible parts, endosperm, or to increase their bioavailability. Iron and zinc fertilization management positively influence their accumulation in cereal grains. Regarding genetic strategies, quantitative genetic studies show the existence of ample variation for iron and zinc accumulation as well as inhibitors or promoters of their bioavailability in cereal grains. However, the genes underlying this variation have rarely been identified and never used in breeding programs. Genetically modified cereals developed by modulation of genes involved in iron and zinc homeostasis, or genes influencing bioavailability, have shown promising results. However, iron and zinc concentration were quantified in the whole grains during most of the studies, whereas a significant proportion of them is lost during milling. This makes it difficult to realistically assess the effectiveness of the different strategies. Moreover, modifications in the accumulation of toxic elements, like cadmium and arsenic, that are of concern for food safety are rarely determined. Trials in living organisms with iron- and zinc-biofortified cereals also remain to be undertaken. This review focuses on the common challenges and their possible solutions related to agronomic as well as genetic iron and zinc biofortification of cereals.",
Arsenic,1327263,"Flow Injection Hydride Generation Atomic Absorption Spectrometry for Determination of Arsenic in Water and Biological Samples from Arsenic-Affected Districts of West Bengal, India, and Bangladesh Abstract: BIOSIS COPYRIGHT: BIOL ABS. The increasing concern over human exposure to arsenic in West Bengal and Bangladesh has necessitated the development of a rapid method for determination of trace levels of arsenic in water and biological samples. We have developed a simple indigenous flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) system for the determination of arsenic in parts-per-billion levels in water and biological samples. The technique is fast, simple, and highly sensitive. The accuracy and p ontained a mixture of arsenite and arsenate and in none of them could we detect methylated arsenic.We also analyzed thousands of urine (inorganic arsenic and its metabolites), hair, and nail samples and hundreds of skin-scale and blood samples of people drinking arsenic-contaminated water and showing arsenical skin lesions. Quality control was assessed by interlaboratory analysis of hair samples. An understanding of arsenic toxicity and metabolism requires quantitation of individ",
Arsenic,1355020,Consumption of Bt rice pollen expressing Cry2Aa does not cause adverse effects on adult Chrysoperla sinica Tjeder (Neuroptera: Chrysopidae) Abstract: ,
Arsenic,1509362,Evaluation of Groundwater for Arsenic Contamination Using Hydrogeochemical Properties and Multivariate Statistical Methods in Saudi Arabia Abstract: ,
Arsenic,1797761,"Formation of gallium arsenide nanostructures in Pyrex glass Abstract: In this paper, we report on a simple, low-cost process to grow GaAs nanostructures of a few nm diameter and ?50 nm height in Pyrex glass wafers. These nanostructures were grown by sequential plasma activation of GaAs and Pyrex glass surfaces using a low-temperature hybrid plasma bonding technology in air. Raman analyses of the activated surfaces show gallium oxide and arsenic oxide, as well as suppressed non-bridging oxygen with aluminate and boroxol chains in glass. The flow of alkaline ions toward the cathode and the replacement of alkaline ions by Ga and As ions in glass result in the growth of GaAs nanostructures in nanopores/nanoscratches in glass. These nanopores/nanoscratches are believed to be the origin of the growth of the nanostructures. It was found that the length of the GaAs nanostructures may be controlled by an electrostatic force. Cross-sectional observation of the bonded interface using high-resolution transmission electron microscopy confirms the existence of the nanostructures. A possible application of the nanostructures in glass is a filtration system for biomolecules.",
Arsenic,2337130,"CO-INOCULATION WITH AM FUNGUS Glomus caledonium AND THE PHOTOHETEROTROPHIC PURPLE NONSULFUR BACTERIUM Rhodopseudomonas palustris RESULTS IN MUTUAL INHIBITION AND LOWER ARSENIC ACCUMULATION OF Nicotiana tabacum L. IN AN ARSENIC CONTAMINATED SOIL Abstract: A greenhouse experiment was undertaken to investigate the effects of an AM fungus Glomus caledonium and a photoheterotrophic purple nonsulfur bacterium (PNSB) Rhodopseudomonas palustris inoculated alone or in combination on the growth and arsenic (As) uptake of tobacco (Nicotiana tabacum L.) in an As-contaminated soil. Mutual inhibition between G. caledonium and R. palustris was observed, which was revealed by the reduction in both mycorrhizal colonization rate and R. palustris abundance in the dual inoculation treatment. The interaction between two tested inoculants was associated with the decreased levels of biomass and P uptake of tobacco and acid phosphatase activity in rhizosphere soil, but related to the increased levels of pH and As concentration of the in-situ soil solution at three sampling dates as compared to the single inoculation. Furthermore, amounts of three rhizosphere soil As fractions and the As concentrations in root and the whole plant were considerably reduced by the G. caledonium and R. palustris inoculated alone as well as in combination. In conclusion, despite mutual inhibition between G. caledonium and R. palustris this interaction did not impair their observed plant As uptake suppression, but further experiments need to be carried out to reveal the mechanisms involved in these responses.",
Arsenic,1255528,"Quantification of trace arsenic in soils by field-portable X-ray fluorescence spectrometry: Considerations for sample preparation and measurement conditions Abstract: Recent technological improvements have led to the widespread adoption of field portable energy dispersive X-ray fluorescence (FP-XRF) by governmental agencies, environmental consultancies and research institutions. FP-XRF units often include analysis modes specifically designed for the quantification of trace elements in soils. Using these modes, X-ray tube based FP-XRF units can offer almost &quot;point and shoot&quot; ease of use and results comparable to those of laboratory based instruments. Nevertheless, FP-XRF analysis is sensitive to spectral interferences as well as physical and chemical matrix effects which can result in decreased precision and accuracy. In this study, an X-ray tube-based FP-XRF analyser was used to determine trace (low ppm) concentrations of As in a floodplain soil. The effect of different sample preparation and analysis conditions on precision and accuracy were systematically evaluated. We propose strategies to minimise sources of error and maximise data precision and accuracy, achieving in situ limits of detection and precision of 6.8ppm and 14.4%RSD, respectively for arsenic. We demonstrate that soil moisture, even in relatively dry soils, dramatically affects analytical performance with a signal loss of 37% recorded for arsenic at 20wt% soil moisture relative to dry soil. We also highlight the importance of the use of certified reference materials and independent measurement methods to ensure accurate correction of field values.",
Arsenic,1597442,"Direct determination of arsenic in beet sugar molasses using nickel as chemical modifier by electrothermal atomic absorption spectrommetry Abstract: A simple electrothermal atomic absorption spectrometric (ETAAS) method is described for direct determination of arsenic in sugar beet molasses samples. Pyrolytic graphite tubes were used as atomizers. The compression between modifiers such as nickel nitrate, palladium nitrate and the mixture of palladium and magnesium nitrate were performed and nickel nitrate selected as the best chemical modifier. The effects of pyrolysis and atomization temperature were also studied and the pyrolysis temperature of 900 °C and atomization temperature of 2300 °C have been chosen for temperature program. The detection limit of the method was 1 ng/mL As in sugar beet molasses samples. The relative standard deviation for ten determination of a spiked sample with concentration of 50 ng/mL As was 2.4%. The accuracy of the method was confirmed by the analysis of spiked samples. The linear rang of calibration is in the range of 1-100 ng/mL of arsenic.",
Arsenic,1937987,"Chronic exposure to emissions from photocopiers in copy shops causes oxidative stress and systematic inflammation among photocopier operators in India Abstract: BACKGROUND: We assessed indoor air quality in photocopier centers and investigated whether occupational exposure to emissions from photocopiers is associated with decline in lung function or changes in haematological parameters, oxidative stress and inflammatory status.<br /><br /><strong>METHODS: </strong>Indoor air quality was monitored in five photocopier centers. Pulmonary function was assessed by spirometry in 81 photocopier operators (64 male and 17 female) and 43 healthy control (31 male and 12 female) subjects. Hematological status, serum thio-barbituric acid reactive substances (TBARS), total ferric reducing antioxidant capacity (FRAC), leukotriene B4 (LTB4), 8-isoprostane, C reactive protein (CRP), interleukin 8 (IL-8), clara cell protein (CC-16), intercellular adhesion molecule 1 (ICAM-1) and eosinophilic cationic protein (ECP) were analyzed. Relationships between cumulative exposure, lung function and inflammatory markers were assessed.<br /><br /><strong>RESULTS: </strong>PM10 and PM2.5 were above the permissible levels in all the photocopier centers, whereas the levels of carbon monoxide, nitrogen oxides, ozone, sulphur dioxide, lead, arsenic, nickel, ammonia, benzene and benzo(a)pyrene were within Indian ambient air quality standards. Lung function was similar in the photocopier operators and control subjects. Serum TBARS was significantly higher and FRAC was lower among photocopier operators when compared to healthy controls. Plasma IL-8, LTB4, ICAM-1 and ECP were significantly higher in the photocopier exposed group.<br /><br /><strong>CONCLUSIONS: </strong>Photocopiers emit high levels of particulate matter. Long term exposure to emissions from photocopiers was not associated with decreased lung function, but resulted in high oxidative stress and systemic inflammation leading to high risk of cardiovascular diseases.",
Arsenic,710857,"Arsenite induces aquaglyceroporin 9 expression in murine livers Abstract: Mice exposed to sodium arsenite show a dose-related accumulation of inorganic arsenic (iAs) and its methylated metabolites in the liver. While the accumulation of iAs forms increased linearly with dose in liver cells, a different pattern was observed in other tissues such as the brain and lung, as well as in the peripheral nerves of the rat. As such, trivalent iAs enters the cells, using aquaglyceroporin transporters to modulate cell arsenic accumulation and cytotoxicity. We investigated here if the dose-related accumulation of arsenic in the liver was related to the expression of aquaglyceroporin 9 (AQP9) in the same organ. CD1 male mice were treated with different concentrations (0, 2.5, 5 or 10mg/kg/day) of sodium arsenite during 1, 3 or 9 days. A significant dose-related, up-regulation of AQP9 mRNA and protein was observed and which was verified by immunohistochemistry in liver sections using specific antibodies. The increased transcription of AQP9 has been observed in fasting and diabetic rats, suggesting that this channel could play a role in the diabetogenic effect of arsenic.",
Arsenic,2029881,"Microbial diversity in high arsenic groundwater in Hetao Basin of inner Mongolia, China Abstract: The microbial diversity and community structure in twenty-one groundwater samples from high arsenic shallow aquifers of Hetao Basin, Inner Mongolia, China was investigated with an integrated approach including polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene phylogenetic analyses. A total of 25 bacterial and 32 archaeal DGGE bands were exercised for sequencing. Phylogenetic analyses showed that the bacterial DGGE bands were dominated by Proteobacteria, and the archaeal bands were dominated by Thaumarchaeota and Euryarchaeota. Based on arsenic concentrations, three samples (corresponding to low, medium, and high level of arsenic, respectively) were selected for construction of 16S rRNA gene clone libraries. A total of 912 (468 and 444 for bacteria and archaea, respectively) 16S rRNA gene clone sequences were obtained and subjected to phylogenetic analyses. The results showed that bacterial communities of these samples were dominated by Acinetobacter, Pseudomonas, Massilia, Dietzia, Planococcus, Brevundimonas, Aquabacterium and Geobacter, and archaeal communities by Nitrosophaera, Thermoprotei and Methanosaeta. The relative abundance of major groups varied as a function of changes in groundwater geochemistry. Acinetobacter, Brevundimonas, Geobacter, Thermoprotei and Methanosaeta dominated in high arsenic samples with high concentrations of methane and Fe(II), and low concentrations of SO2- (4) and NO- (3), while Pseudomonas and Nitrosophaera were abundant in low arsenic groundwater. These results imply that microbes play an important role in arsenic mobilization in the shallow aquifers of Hetao Basin, Inner Mongolia.",
Arsenic,1677532,"A novel arsenate reductase from the bacterium Thermus thermophilus HB27: Its role in arsenic detoxification Abstract: Microorganisms living in arsenic-rich geothermal environments act on arsenic with different biochemical strategies, but the molecular mechanisms responsible for the resistance to the harmful effects of the metalloid have only partially been examined. In this study, we investigated the mechanisms of arsenic resistance in the thermophilic bacterium Thermus thermophilus HB27. This strain, originally isolated from a Japanese hot spring, exhibited tolerance to concentrations of arsenate and arsenite up to 20mM and 15mM, respectively; it owns in its genome a putative chromosomal arsenate reductase (TtarsC) gene encoding a protein homologous to the one well characterized from the plasmid pI258 of the Gram+bacterium Staphylococcus aureus. Differently from the majority of microorganisms, TtarsC is part of an operon including genes not related to arsenic resistance; qRT-PCR showed that its expression was four-fold increased when arsenate was added to the growth medium. The gene cloning and expression in Escherichia coli, followed by purification of the recombinant protein, proved that TtArsC was indeed a thioredoxin-coupled arsenate reductase with a kcat/KM value of 1.2×10(4)M(-1)s(-1). It also exhibited weak phosphatase activity with a kcat/KM value of 2.7×10(-4)M(-1)s(-1). The catalytic role of the first cysteine (Cys7) was ascertained by site-directed mutagenesis. These results identify TtArsC as an important component in the arsenic resistance in T. thermophilus giving the first structural-functional characterization of a thermophilic arsenate reductase.",
Arsenic,1337799,"The molecular basis of phosphate discrimination in arsenate-rich environments Abstract: Arsenate and phosphate are abundant on Earth and have striking similarities: nearly identical pK(a) values, similarly charged oxygen atoms, and thermochemical radii that differ by only 4% (ref. 3). Phosphate is indispensable and arsenate is toxic, but this extensive similarity raises the question whether arsenate may substitute for phosphate in certain niches. However, whether it is used or excluded, discriminating phosphate from arsenate is a paramount challenge. Enzymes that utilize phosphate, for example, have the same binding mode and kinetic parameters as arsenate, and the latter's presence therefore decouples metabolism. Can proteins discriminate between these two anions, and how would they do so? In particular, cellular phosphate uptake systems face a challenge in arsenate-rich environments. Here we describe a molecular mechanism for this process. We examined the periplasmic phosphate-binding proteins (PBPs) of the ABC-type transport system that mediates phosphate uptake into bacterial cells, including two PBPs from the arsenate-rich Mono Lake Halomonas strain GFAJ-1. All PBPs tested are capable of discriminating phosphate over arsenate at least 500-fold. The exception is one of the PBPs of GFAJ-1 that shows roughly 4,500-fold discrimination and its gene is highly expressed under phosphate-limiting conditions. Sub-ångström-resolution structures of Pseudomonas fluorescens PBP with both arsenate and phosphate show a unique mode of binding that mediates discrimination. An extensive network of dipole-anion interactions, and of repulsive interactions, results in the 4% larger arsenate distorting a unique low-barrier hydrogen bond. These features enable the phosphate transport system to bind phosphate selectively over arsenate (at least 10(3) excess) even in highly arsenate-rich environments.",
Arsenic,1022151,"Embryotoxicity assessment of developmental neurotoxicants using a neuronal endpoint in the embryonic stem cell test Abstract: The embryonic stem cell test (EST) is a validated in vitro embryotoxicity test; however, as the inhibition of cardiac differentiation alone is used as a differentiation endpoint in the EST, it may not be a useful test to screen embryotoxic chemicals that affect the differentiation of noncardiac tissues. Previously, methylmercury (MeHg), cadmium and arsenic compounds, which are heavy metals that induce developmental neurotoxicity in vivo, were misclassified as nonembryotoxic with the EST. The aim of this study was to improve the EST to correctly screen such developmental neurotoxicants. We developed a neuronal endpoint (Tuj-1 ID(50) ) using flow cytometry analysis of Tuj-1-positive cells to screen developmental neurotoxicants (MeHg, valproic acid, sodium arsenate and sodium arsenite) correctly using an adherent monoculture differentiation method. Using Tuj-1 ID(50) in the EST instead of cardiac ID(50) , all of the tested chemicals were classified as embryotoxic, while the negative controls were correctly classified as nonembryotoxic. To support the validity of Tuj-1 ID(50) , we compared the results from two experimenters who independently tested MeHg using our modified EST. An additional neuronal endpoint (MAP2 ID(50) ), obtained by analyzing the relative quantity of MAP2 mRNA, was used to classify the same chemicals. There were no significant differences in the three endpoint values of the two experimenters or in the classification results, except for isoniazid. In conclusion, our results indicate that Tuj-1 ID(50) can be used as a surrogate endpoint of the traditional EST to screen developmental neurotoxicants correctly and it can also be applied to other chemicals.",
Arsenic,1343112,"Response of embryos of the sea urchin Strongylocentrotus purpuratus to aqueous petroleum waste includes the expression of a high molecular weight glycoprotein Abstract: The present study investigated the sublethal effects of the largest aqueous waste associated with offshore oil development, produced water (PW), on sea urchin embryo development. PW inhibited normal gastrulation in purple sea urchin (Strongylocentrotus purpuratus) embryos exposed at the hatching stage. The exposed embryos did not form complete archenterons, and secondary mesenchyme cells exhibited an unusual behavior with respect to the wall of the blastocoelic cavity. In addition, an abundance of extracellular matrix was observed in the blastocoelic cavities in the embryos exposed to higher concentrations of PW. An inhibition of the development of embryos through the pluteus stage was observed as a result of PW exposure. This was manifested by inhibition of normal spicule formation with concomitant abnormal pluteus morphology. To determine if a biochemical stress response occurs as a result of PW exposure, embryos at the early gastrula stage were exposed to PW for 2 h, followed by an additional 1 h in 3H-leucine and PW. These embryos expressed a 253 kDa protein as observed by one-dimensional SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis and autoradiography. This protein could occasionally be observed in gels stained for protein, and was glycosylated as demonstrated by staining with periodic acid Schiff (PAS). The 70 to 73 kDa heat-shock proteins previously described in sea urchin embryos (and other organisms) as a result of stress were not synthesized as a result of PW exposure. Heat shock did not induce synthesis of the 253 kDa glycoprotein. Combined PW and heat-shock exposure elicited both the heat-shock response (73 kDa protein) as well as expression of the 253 kDa glycoprotein. These data demonstrate the use of expression of endogenous macromolecular markers to distinguish exposures of embryos to different perturbations. Arsenic (as sodium arsenite), a metal constituent of PW, also induced the 253 kDa glycoprotein in early gastrula-stage embryos. We suggest that this glycoprotein may be a marker for PW (and a metal constituent) exposure in sea urchin embryos, and may be related to morphological abnormalities.",
Arsenic,1677605,"Taurine prevented cell cycle arrest and restored neurotrophic gene expression in arsenite-treated SH-SY5Y cells Abstract: The study investigated the effect of taurine on cell viability and neurotrophic gene expression in arsenite-treated human neuroblastoma SH-SY5Y cells. Arsenite-induced intracellular reactive oxygen species (ROS) and interrupted cell cycle in SH-SY5Y cells. In addition, arsenite reduced mitochondria membrane potential (MMP) and decreased neurotrophic gene expressions such as n-myc downstream-regulated gene 4 (NDRG-4), brain-derived neurotrophic factor (BDNF) and sirtuin-1 (SIRT-1) in SH-SY5Y cells. In parallel, taurine prevented cell cycle, restored MMP and reduced the intracellular ROS level, and taurine recovered NDRG-4, BDNF and SIRT-1 gene expressions in arsenite-treated SH-SY5Y cells while taurine alone has no effect on these parameters.",1
Arsenic,2149105,"Arsenic removal from contaminated groundwater by membrane-integrated hybrid plant: Optimization and control using Visual Basic platform Abstract: A simulation software (ARRPA) has been developed in Microsoft Visual Basic platform for optimization and control of a novel membrane-integrated arsenic separation plant in the backdrop of absence of such software. The user-friendly, menu-driven software is based on a dynamic linearized mathematical model, developed for the hybrid treatment scheme. The model captures the chemical kinetics in the pre-treating chemical reactor and the separation and transport phenomena involved in nanofiltration. The software has been validated through extensive experimental investigations. The agreement between the outputs from computer simulation program and the experimental findings are excellent and consistent under varying operating conditions reflecting high degree of accuracy and reliability of the software. High values of the overall correlation coefficient (R (2)?=?0.989) and Willmott d-index (0.989) are indicators of the capability of the software in analyzing performance of the plant. The software permits pre-analysis, manipulation of input data, helps in optimization and exhibits performance of an integrated plant visually on a graphical platform. Performance analysis of the whole system as well as the individual units is possible using the tool. The software first of its kind in its domain and in the well-known Microsoft Excel environment is likely to be very useful in successful design, optimization and operation of an advanced hybrid treatment plant for removal of arsenic from contaminated groundwater.",
Arsenic,1070376,"Release of Apoptotic Cytochrome c from Mitochondria by Dimethylarsinous Acid (DMAIII) Occurs Through Interaction with Voltage Dependent Anion Channel (VDAC) In Vitro Abstract: Arsenic is known to be a human carcinogen as well as one of the most effective drugs for treatment of patients with acute promyelocytic leukemia (APL). Although it has been reported that arsenic intermediate metabolites monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), which transformed by methylation reactions are more reactive and toxic than that of inorganic precursor arsenite (iAsIII), however, the detailed mechanism is poorly understood. Here, we studied the effects of three arsenic compounds (i.e., iAsIII, MMAIII and DMAIII) on mitochondrial permeability transition pore (mPTP) as well as the release of apoptotic cytochrome c after incubating with rat liver mitochondria. Inorganic iAsIII had no effect on mitochondrial swelling even at higher concentration i.e. up to 100 µM, but it was significantly induced in the presence of Ca2+. Additionally, mitochondrial swelling was strongly induced by exposure to the methylated MMAIII and DMAIII in dose dependent manner without Ca2+, suggesting the methylated forms may have potent effect on cellular mitochondria. Although mitochondrial swelling was completely inhibited in the presence of Cyclosporin A (a inhibitor of mitochondrial permeability transition) or Ruthenium Red (a inhibitor of Ca2+ uniporter) following exposure to methylated arsenicals, the release of apoptotic Cytochrome c (Cyt c) form mitochondria were not inhibited, indicating the release of Cyt c is probably not dependent the mPTP opening. In addition, inhibitor of Bax (e.g., Bax-inhibiting peptide) did not reduce the Cyt c release from mitochondria by formation of Bax-VDAC complex process, while the recombinant Bcl-xL proteins significantly reduced the release of Cyt c with exposure to DMAIII, suggesting the dimethylated DMAIII directly interacted with voltage dependent anion channel (VDAC) in mitochondria and resulted in the release of Cyt c from mitochondria.",
Arsenic,627503,"Risk of carotid atherosclerosis associated with genetic polymorphisms of apolipoprotein E and inflammatory genes among arsenic exposed residents in Taiwan Abstract: Arsenic had been reported to be associated with carotid atherosclerosis. However, there were few studies to evaluate the association between the susceptible gene of lipid metabolism and inflammation and carotid atherosclerosis among arsenic exposure residents. The aim of the study was to investigate the associations between the genetic polymorphisms of APOE and MCP-1 and the risk of carotid atherosclerosis among residents of Lanyang Basin in Taiwan which was a newly confirmed arsenic-endemic area. In total, 479 residents who had been genotyped of these two genes and examined the severity of carotid atherosclerosis were included in this study. The study subjects with carotid intima media thickness (IMT) >or=1.0 mm or with the observable plaque in the extracranial carotid artery were diagnosed as carotid atherosclerosis. A significantly age- and gender-adjusted odds ratio of 2.0 for the development of carotid atherosclerosis was observed in study subjects with epsilon4 allele of APOE than those without epsilon4 allele. Compared with study subjects who carried wild genotypes of APOE and MCP-1, those with both risk genotypes of APOE and MCP-1 had 2.5-fold risk of carotid atherosclerosis after adjustment for age and gender, revealing a significant dose-response relationship between number of risk genotypes of these genes and risk of carotid atherosclerosis. Additionally, study subjects with two risk genotypes of APOE and MCP-1 and either had ingested well water contained arsenic level >10 microg/L or had arsenic exposure >0.22 mg/L-year would have strikingly highest risk of 10.3-fold and 15.7-fold, respectively, for the development carotid atherosclerosis, showing significant joint effect of arsenic exposure and risk genotypes of APOE and MCP-1.",
Arsenic,1348119,INDUCTION OF 4 PROTEINS IN CHICK-EMBRYO CELLS BY SODIUM ARSENITE Abstract: ,
Arsenic,627048,"Vitamin C protects HL60 and U266 cells from arsenic toxicity Abstract: Although there is no compelling evidence that vitamin C has antitumor activity in humans, clinical trials are testing the hypothesis that ascorbic acid (AA) will enhance the efficacy of arsenic trioxide (As2O3) in myeloma. In vitro, AA cytotoxicity depends on its interaction with free transition metal ions in culture media leading to the generation of H2O2 and other reactive oxygen species (ROSs). Therefore, to circumvent the extracellular in vitro pro-oxidant effects of AA, we loaded HL60, U266, and RPMI-8226 cells with vitamin C by incubation with dehydroascorbic acid (DHA). Loading cells in this manner resulted in prominent, dose-dependent protection of As2O3-treated cells as measured by viability, colony formation, and apoptosis assays. Glutathione depletion enhanced cell sensitivity to the cytotoxic effects of As2O3 and vitamin C loading provided protection. AA was found to generate cytotoxic concentrations of H2O2 in culture medium without cells and copper/iron chelators inhibited this reaction. However, AA did not generate H2O2 in simple buffer or human plasma. Direct incubation with AA resulted in increased intracellular ROSs, whereas DHA incubation decreased it. These results clarify an apparent paradox and indicate that vitamin C loading in HL60, U266, and RPMI-8226 cells ameliorates As2O3 cytotoxicity.",
Arsenic,1519012,"Selected trace metals (As, Cd and Hg) distribution and contamination in the coastal wetland sediment of the northern Beibu Gulf, South China Sea Abstract: Contamination with As, Cd and Hg, their spatial and temporal distribution are reported from the coastal wetland sediments of the northern Beibu Gulf, South China Sea. The content of As, Cd, Hg and TOC in surface sediments is 8.1±5.8 ?g g?¹, 0.08±0.14?g g?¹, 0.034±0.028 ?g g?¹ and 0.45±0.39%, respectively. The mean sedimentation rates are 0.93-1.37 cm year?¹ during 1920s to 2008 determined by ²¹?Pb and ¹³?Cs dating in three cores. The vertical profiles of As, Cd and Hg content in the cores retrieved from Qin and Nanliu River estuaries show increasing trends during 1985-2008 due to anthropogenic impact caused by local economic development. Locally the surface sediments have potential ecological risk of As to benthos according to the NOAA sediment quality guidelines.",
Arsenic,1347669,Cytotoxicity of arsenic trioxice (As2O3) to leukemic and normal CD34+cells is cell-cycle-dependent Abstract: ,
Arsenic,627687,"Inorganic arsenic levels in baby rice are of concern Abstract: Inorganic arsenic is a chronic exposure carcinogen. Analysis of UK baby rice revealed a median inorganic arsenic content (n=17) of 0.11 mg/kg. By plotting inorganic arsenic against total arsenic, it was found that inorganic concentrations increased linearly up to 0.25 mg/kg total arsenic, then plateaued at 0.16 mg/kg at higher total arsenic concentrations. Inorganic arsenic intake by babies (4-12 months) was considered with respect to current dietary ingestion regulations. It was found that 35% of the baby rice samples analysed would be illegal for sale in China which has regulatory limit of 0.15 mg/kg inorganic arsenic. EU and US food regulations on arsenic are non-existent. When baby inorganic arsenic intake from rice was considered, median consumption (expressed as microg/kg/d) was higher than drinking water maximum exposures predicted for adults in these regions when water intake was expressed on a bodyweight basis.",
Arsenic,1357301,"Induction of Preneoplastic Lesions by Sodium Arsenite in Human Fetal Respiratory Epithelia in Organ Culture Abstract: In this study arsenic (7440382) induced preneoplastic lesions were noted in human fetal respiratory tissues in organ culture. Human fetal trachea (HFT) and human fetal lung (HFL) cell cultures were derived following abortion of 16 to 25 week old fetuses. Cells were exposed up to 9 micromolar (microM) sodium-arsenite (7784465) and 34microM N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Explants were prepared from the cell cultures and analyzed by light and electron microscopy. Following treatment with MNNG for 4 to 8 days, hyperplasia of basal cells was common and up to six layers of cells were noted. Epidermoid metaplasia occurred. Between 11 and 14 days more epidermoid metaplasia formed and dysplasia appeared. In 18 to 21 days serious dysplasia was noted. By 25 days the hyperplastic epithelium was changed into one or two layers of flat cells. Hyperplasia and epidermoid metaplasia were noted in glandular epithelium of HFT in 18 to 21 days. Treatment with 1microM arsenic caused hyperplasia of basal cells from the fourth day of incubation. The epithelium consisted of five to six layers of cells during days seven through 12. The epithelium then became one or two layers of flat cells, and no metaplasia or dysplasia was noted. Treatment with 5 to 9microM arsenic resulted in serious atrophy, occasional necrosis, and sloughing of the epithelium during 3 to 6 days of incubation. On day 12, cellular atypia was noted in the epithelium which consisted of one layer of squamous cells. Following treatment of human fetal lung with 1microM arsenic for 15 or 16 days, two dysplastic foci of bronchiolar epithelium were noted from 30 pieces of HFL. These findings support the belief that arsenic is carcinogenic to the human lung.",
Arsenic,1356867,"Impact Of Model Misspecification On A Physiologically-Based Pharmacokinetic Model For DMA Abstract: Inorganic arsenic in drinking water and organic arsenic used as herbicides both pose health risks. Using experimental data, a Physiologically Based Pharmacokinetic (PBPK) modeling has been applied to dimethylarsinic acid (DMA) in order to quantify dose metrics associated with health effects. A nine compartment intravenous PBPK model (venous, lung, lung blood, skin, kidney, urine, bladder, liver, and rest-of-body) was developed for mice that can be extrapolated to humans. This work describes part of the process of model development, and potential errors that can arise. To describe the pharmacokinetics, we initially assumed the simplest case, blood flow-limited distribution in every organ. However, this type of mathematical description was incomplete in that the amounts of DMA in the organs exceeded the dose. After examining the assumptions used for the lung, we decided that the blood flow-limited case was inappropriate for this organ. When we added membrane-limited terms to the lung blood equation, we could then account for lung tissue accumulation. Since the lung is a target organ, we wanted to ensure that we were describing accumulation correctly. The next organ to be described mathematically was the kidney. The fits obtained assuming zero order transport through the glomerular capsule were not satisfactory. An additional improvement included in the model is a saturable mechanism for the clearance of DMA in the kidney. In summary, this model describes the inclusion of more complex descriptions of the lung and kidney, resulting in a combination of different approaches used in PBPK modeling.",
Arsenic,1794818,"Germanium as a tool to dissect boron toxicity effects in barley and wheat Abstract: Tolerance to boron (B) toxicity in barley (Hordeum vulgare L.) is partially attributable to HvNIP2;1, an aquaporin with permeability to B, as well as to silicon, arsenic and germanium (Ge). In this study, we mapped leaf symptoms of Ge toxicity in a doubled-haploid barley population (Clipper × Sahara 3771). Two quantitative trait loci (QTL) associated with Ge toxicity symptoms were identified, located on Chromosomes 6H and 2H. These QTL co-located with two of four B toxicity tolerance loci previously mapped in the same population. The B toxicity tolerance gene underlying the 6H locus encodes HvNIP2;1, whereas the gene(s) and mechanisms underlying the 2H locus are as yet unknown. We provide examples of the application of Ge in studying specific aspects of B toxicity tolerance in plants, including screening of wheat (Triticum aestivum L.) and barley populations for altered function of HvNIP2;1 and related proteins. In particular, Ge may facilitate elucidation of the mechanism and gene(s) underlying the barley Chromosome 2H B tolerance locus.",
Arsenic,1508601,"Antibiotic resistance, antimicrobial residues and bacterial community composition in urban wastewater Abstract: This study was based on the hypothesis that the occurrence of antimicrobial residues and antibiotic resistant bacteria in the sewage could be correlated with the structure and composition of the bacterial community and the antibiotic resistance loads of the final effluent. Raw and treated wastewater composite samples were collected from an urban treatment plant over 14 sampling dates. Samples were characterized for the i) occurrence of tetracyclines, penicillins, sulfonamides, quinolones, triclosan, arsenic, cadmium, lead, chromium and mercury; ii) antibiotic resistance percentages for tetracycline, sulfamethoxazole, ciprofloxacin and amoxicillin and iii) 16S rRNA gene-DGGE patterns. The data of corresponding samples, taking into account the hydraulic residence time, was analyzed using multivariate analysis. Variations on the bacterial community structure of the final effluent were significantly correlated with the occurrence of tetracyclines, penicillins, sulfonamides, quinolones and triclosan in the raw inflow. Members of the class Epsilonproteobacteria presented positive correlations with those antimicrobials, whereas negative correlations were observed with Beta and Gammaproteobacteria and Firmicutes. Antibiotic resistance percentages presented different trends of variation in heterotrophs/enterobacteria and in enterococci, varied over time and after wastewater treatment. Antibiotic resistance was positively correlated with the occurrence of tetracyclines residues and high temperature. A relationship between antibiotic residues, bacterial community structure and composition and antibiotic resistance is demonstrated. Further studies, involving more wastewater treatment plants may help to elucidate this complex relationship.",
Arsenic,1016270,"In vivo distribution of arsenic after i.p. injection of arsonoliposomes in balb-c mice Abstract: We recently showed that arsonoliposomes (novel arsenic containg liposomes) demonstrate differential toxicity towards various types of cancer and normal cells, in cell culture studies, as well as anti-parasitic activity. In this study, the in-vivo distribution of the active moiety of these vesicles, As, is evaluated. Sonicated arsonoliposomes were prepared using the arsonolipid with palmitic acid acyl chain (C16) mixed with egg-phosphatidyl choline (PC) and cholesterol (Chol) [C16/PC/Chol at 8:12:10 mol/mol/mol]. A dose of arsonoliposomes, corresponding to 5 mg arsenate/kg was administered by intraperitoneal injection in balb-c mice. At various time points post-injection the mice were sacrificed and the distribution of As in the organs was measured, by atomic absorption spectroscopy. Results demonstrate that a high portion of the dose administered is rapidly excreted; since 1-h post-injection only about 30% of the dose administered was detected cumulatively in the animal tissues. After this the elimination of arsenic was a slow process with a total body elimination rate constant of 0.023 h(-1), corresponding to a half-life of 30 h. Tissues with the highest arsenic concentration during the study period are: spleen-kidneys-stomach, followed by lung, liver, intestines-heart, carcass+skin and finally blood. No acute toxicity, or effect on the body or organ weight of the mice was observed.",
Arsenic,1017091,"Determinants of arsenicosis patients' perception and social implications of arsenic poisoning through groundwater in Bangladesh Abstract: Adverse human health effects ranging from skin lesions to internal cancers as well as widespread social and psychological problems caused by arsenic contaminated drinking water in Bangladesh may be the biggest arsenic calamity in the world. From an arsenicosis patients survey, this paper empirically analyzes the determinants of arsenicosis patients' perception about chronic arsenic poisoning and social and psychological implications of arsenicosis. In this study, cross-sectional data were collected from the Matlab and Hajiganj Upzillas of Chandpur district which are known to be highly contaminated with arsenic in their underground water. Respondents informed that arsenic poisoning causes a wide range of social and psychological problems. Female respondents were less vulnerable in the case of social problems (p &lt; 0.01) and more vulnerable for the psychological problems (p &lt; 0.001) of arsenicosis than male respondents. The results based on logit analysis showed that education (p &lt; 0.01) and household income (p &lt; 0.05) were significantly correlated to respondents' perception about arsenicosis. The arsenicosis related special program (s) needs a clear understanding of people's perception about arsenic exposure for abating the health burden as well as social and psychological problems.",
Arsenic,2337111,"Arsenic removal from groundwater by acclimated sludge under autohydrogenotrophic conditions Abstract: Arsenic in the environment is attracting increasing attention due to its chronic health effects. Although arsenite (As(III)) is generally more mobile and more toxic than arsenate (As(V)), reducing As(V) to As(III) may still be a means for decontamination, because As(III) can be removed from solution by precipitation with sulfide or by adsorption or complexation with other metal sulfides. The performance of As(V) bio-reduction under autohydrogenotrophic conditions was investigated with batch experiments. The results shoved that As(V) reduction was a biochemical process while both acclimated sludge and hydrogen were essential. Most of the reduced arsenic remained in a soluble form, although 20% was removed with no addition of sulfate, while 82% was removed when sulfate was reduced to sulfide. The results demonstrated that the reduced arsenic was re-sequestered in the precipitates, probably as arsenic sulfides. Kinetic analysis showed that pseudo first-order kinetics described the bio-reduction process better than pseudo second-order. In particular, the influences of pH and temperature on As(V) reduction by acclimated sludge under autohydrogenotrophic conditions and total soluble As removal were examined. The reduction process was highly sensitive to both pH and temperature, with the optimum ranges of pH 6.5-7.0 and 30-40 degrees C respectively. Furthermore, Arrhenius modeling results for the temperature effect indicated that the As(V) reduction trend was systematic. Total soluble As removal was consistent with the trend of As(V) reduction.",
Arsenic,1519011,"Screening heavy metals levels in hair of sanitation workers by X-ray fluorescence analysis Abstract: This work presents a study of human hair as a bio-indicator for detection of heavy metals as part of environmental health surveillance programs project to develop a subject of interest in the biomedical and environmental sciences. A total of 34 hair samples were analyzed that consisting of 29 samples from sanitation workers and five samples from students. The hair samples were prepared and treated in accordance to the International Atomic Energy Agency (IAEA) recommendations. The concentrations of heavy metals were analyzed using the energy dispersive X-ray fluorescence (EDXRF) technique by X-50 Mobile X-ray Fluorescence (XRF) at Oceanography Institute, Universiti Malaysia Terengganu. The performance of EDXRF analyzer was tested by Standard Reference Material (SRM 2711) Montana Soil which was in good agreement with certified value within 14% deviations except for Hg. While seven heavy metals: Mn, Fe, Ni, Cu, Zn, Se, and Sb were detected in both groups, three additional elements, i.e. As, Hg and Pb, were detected only in sanitation workers group. For sanitation workers group, the mean concentration of six elements, Mn, Fe, Cu, Zn, Se, and Sb, shows elevated concentration as compared to the control samples concentration. Results from both groups were compared and discussed in relation to their respective heavy metals concentrations.",
Arsenic,1031385,"Influence of pyrometallurgical copper production on the environment Abstract: In this paper the influence of pyrometallurgical treatment of copper sulphide minerals and pyrite on the environment from the aspect of ambient air pollutions is considered. Results of emission of SO(2) and particulate matter from the location with the most pollution are presented. According to the results it could be seen that the Bor's citizen were exposed to the high concentration of SO(2) and arsenic which were found to be multiple over the Serbian legislative limits during 2007. Also, the reasons and consequences of this pollution were analysed.",
Arsenic,2064142,Simultaneous removal of Cu and PAHs from dredged sediments using flotation Abstract: ,
Arsenic,627146,"Cytolethality of glutathione conjugates with monomethylarsenic or dimethylarsenic compounds Abstract: Arsenicals are known to be toxic and carcinogenic in humans. Inorganic arsenicals are enzymatically methylated to monomethylarsonic acid (MMAsV) and dimethylarsinic acid (DMAsV), which are the major pentavalent methyl arsenic metabolites. Recent reports indicate that trivalent methyl arsenicals are produced through methylation of inorganic arsenicals and participate in arsenic poisoning. Trivalent methyl arsenicals may be generated as arsenical-glutathione conjugates, such as monomethylarsonous diglutathione (MMAsIIIDG) and dimethylarsinous glutathione (DMAsIIIG), during the methylation process. It has been well known that reduced glutathione (GSH) reduces MMAsV and DMAsV in vitro, and produces MMAsIIIDG and DMAsIIIG. Some studies have shown that exogenous GSH increased cytolethality of MMAsV and DMAsV in vitro, while other studies have suggested that exogenous GSH decreased them. In this study, we examined the true effects of exogenous GSH on the cytolethality of MMAsV and DMAsV by investigating reactions between various concentrations of MMAsV or DMAsV and GSH. GSH significantly increased the cytolethality and cellular uptake of pentavalent methyl arsenicals when GSH over 25 mM was pre-incubated with mM levels of arsenicals, and this cytolethality might have been caused by arsenical-GSH conjugate generation. However, GSH at less than 25 mM did not affect the cytolethality and cellular uptake of pentavalent methyl arsenicals. These findings suggest that high concentrations of arsenicals and GSH are needed to form arsenical-GSH conjugates and to show significant cytolethality. Furthermore, we speculated that MMAsIIIDG and DMAsIIIG may separate into trivalent methyl arsenicals and glutathione, which are then transported into cells where they show significant cytolethality.",
Arsenic,189711,"Risk assessment on renal dysfunction caused by co-exposure to arsenic and cadmium using benchmark dose calculation in a Chinese population Abstract: Arsenic and cadmium are important inorganic toxicants in the environment. Humans certainly have the potential to be exposed to the mixtures of arsenic and cadmium, but the toxicological interactions of these inorganic mixtures are poorly defined. A general population co-exposed to arsenic and cadmium, was selected in China. The total number of participants was 245, made up of 122 in the arsenic-cadmium polluted area, 123 in the non polluted area. Urinary arsenic (UAs) and cadmium (UCd) were determined by atomic absorption spectrometry as exposure biomarkers and beta2-microglobulin (Ubeta2MG), albumin (UALB), N-acetyl-beta2-glucosaminidase (UNAG) in urine were determined as effect biomarkers. The benchmark dose (BMD) and the lower confidence limit on the benchmark dose (LBMD) were calculated to estimate the critical concentration of UAs and UCd. UAs and UCd concentrations in the polluted area were significantly higher than those in the non polluted area (P < 0.01). The levels of Ubeta2MG, UALB and UNAG in the polluted area were significantly higher than those in the non polluted area (P < 0.01). The BMD/LBMD of UAs and UCd for a 10% level of risk above the background level were estimated as 121.91/102.11 microg/g creatinine and 1.05/0.88 microg/g creatinine. It was suggested that the lower confidence limit of population critical concentration of UAs and UCd for renal dysfunction for 10% excess risk level above the background, which is obtained from LBMD, may need to be kept below 102 and 0.88 microg/g creatinine in order to prevent renal damage in general population co-exposed to arsenic and cadmium. It is indicated that combined effect of arsenic and cadmium were additive effect and/or synergistic effect, and cadmium may potentiate arsenic nephrotoxicity during the long-term and co-exposure to arsenic and cadmium in humans.",
Arsenic,93325,"U-shaped dose response in vasomotor tone: a mixed result of heterogenic response of multiple cells to xenobiotics Abstract: U-shaped response has been frequently encountered in various biological areas including epidemiology, toxicology, and oncology. Despite its frequent observation, the theory of U-shaped response has been crippled by the lack of a robust mechanism underlying and incomplete in vitro and in vivo correlation. In the present study, a novel mechanism is provided for a U-shaped response, based on the findings of agonist-induced vasomotor tone change affected by menadione (MEN) (synthetic vitamin K3), a reactive oxygen species generator, and arsenic, an environmental pollutant, which showed typical U-shaped responses in both in vitro aortic contractile response and in vivo blood pressure. U-shaped responses by MEN and arsenic were a combined result from heterogenic susceptibilities and responses of multiple target cells composing blood vessels, that is, endothelium and smooth muscle. Notably, endothelium, a regulator of vasomotor tone, was primarily affected by low-dose stimuli, whereas smooth muscle, an effector of vascular contraction, was affected later by high-dose. The dysfunction of smooth muscle was produced by high-dose MEN-induced hydrogen peroxide, resulting in the attenuation of vascular contractile reactivity, whereas low-dose MEN-induced superoxide led to the quenching of vasodilatory nitric oxide in endothelial cells, resulting in the enhancement of vasoconstriction. This mechanistic theory, the difference in susceptibilities and responses to a common stimulus between regulator and effector components of a system, could give a new insight into the explanation of various U-shaped responses and provide a new evidence for the need of the risk assessment of toxicants with a wider dose range.",
Arsenic,154622,"Plasmid DNA damage caused by methylated arsenicals, ascorbic acid and human liver ferritin Abstract: Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, P<0.05) and by DMA(III) was much higher (16.3 nM/min, P<0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe2+ concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis.",
Arsenic,628491,"Association of arsenic and kidney dysfunction in people with diabetes and validation of its effects in rats Abstract: We studied villagers with and without diabetes from arsenic-endemic areas and a nearby control site in Xinjiang Autonomous Region, PR China. Water and urinary arsenic were assayed for exposure measurement. Urinary NAG (N-acetyl-beta-glucosaminidase), a kidney function test, blood glucose, triglyceride, cholesterol, high density lipid and low density lipid were measured. Villagers from endemic areas were found to have higher urinary arsenic concentrations. The NAG results also suggest that chronic arsenic exposure presents a significant adverse impact on the kidney function of villagers in the endemic areas. However, blood glucose levels of diabetes individuals were lower than those from the control site. These observations were validated in rats which were chronically exposed to arsenic in drinking water. The distinct relationship between chronic arsenic exposure and diabetes mellitus requires further investigation. A rodent model is a useful tool for study of this type.",
Arsenic,1519023,"Impact of dissolved silica on arsenite removal by nano-particulate FeS and FeS-coated sand Abstract: This work evaluated the inhibitory effect of dissolved silica on arsenite adsorption to nanoparticulate FeS (NP-FeS) or mackinawite and FeS-coated sand (CS-FeS) sorbents. Arsenite retention by the NP-FeS solid was not affected by dissolved silicate over a wide range in pH, in contrast to the known inhibitory effect of dissolved silica on As(III) uptake by Fe-(hydr)oxide systems. However, some inhibition was observed in CS-FeS system at pH 9. This latter result is attributed to the co-existence of both FeS and small amounts of Fe-(hydr)oxide phases on the sand surface. Given the ubiquitous presence of dissolved Si in groundwater, FeS-based sorbents may have an advantage for As retention compared to those based on Fe-(hydr)oxides in reducing subsurface environments.",
Arsenic,1326985,"Arsenite induces aberrations in meiosis that can be prevented by coadministration of N-acetylcysteine in mice Abstract: <strong>OBJECTIVE: </strong>To evaluate in vitro effects of arsenite and of arsenite plus N-acetylcysteine on mouse oocyte meiosis.<br /><br /><strong>DESIGN: </strong>Morphological study using mouse oocytes submitted to in vitro maturation (IVM).<br /><br /><strong>SETTING: </strong>Laboratory of reproductive biology.<br /><br /><strong>ANIMAL(S): </strong>Six-week-old CD-1 mice superovulated with pregnant mare serum gonadotropin.<br /><br /><strong>INTERVENTION(S): </strong>During IVM, mouse oocytes were exposed to arsenite alone or to arsenite plus N-acetylcysteine.<br /><br /><strong>MAIN OUTCOME MEASURE(S): </strong>Meiotic anomalies were assessed using immunofluorescence microscopy and PolScope (Cambridge Research and Instrumentation, Boston, MA) imaging.<br /><br /><strong>RESULT(S): </strong>In vitro arsenite administration produced dose-dependent and time-dependent meiotic anomalies, characterized by spindle disruption or chromosome misalignment. After 12-14 hours of IVM, exposure to 2 microg/mL of arsenite for 12-14 hours or to 8 microg/mL of arsenite for 2 hours arrested oocyte maturation at the germinal vesicle or germinal-vesicle breakdown stage. Exposure to 4 microg/mL of arsenite for 2 hours arrested oocyte maturation at metaphase I stage in 95% of exposed oocytes (80% exhibiting abnormalities) after 12-14 hours in IVM. After 12-14 hours in IVM, of the oocytes exposed to 2 microg/mL of arsenite for 2 hours, only 15% reached the meiosis II stage (5% exhibiting abnormalities). After 15-17 hours in IVM, however, of the oocytes exposed to 2 microg/mL of arsenite for 2 hours, 65.2% reached the meiosis II stage (43.5% exhibiting abnormalities). Co-administration of N-acetylcysteine prevented the arsenite-induced meiotic abnormalities and the delayed IVM.<br /><br /><strong>CONCLUSION(S): </strong>In vitro arsenite exposure caused meiotic abnormalities that were prevented by co-administration of N-acetylcysteine, suggesting that arsenite-induced meiotic aberrations are mediated by reactive oxygen species.",
Arsenic,2347770,"EFFECTS OF VITAMIN C ON ANTIOXIDANT SYSTEMS AND STEROIDOGENIC ENZYMES IN SODIUM FLUORIDE-EXPOSED TM4 SERTOLI CELLS Abstract: Fluoride, which is commonly found in drinking water and nutrients, threatens the environment and human life. Fluoride damages cells by causing free radical formation and affects male reproductive function by preventing spermatogenesis, changing the activity of spermatogenetic enzymes, and consequently leading to reduced reproductive capacity. A sufficient amount of antioxidants should be consumed in order to prevent oxidative stress of free radicals and minimize their effect. Vitamin C is a powerful antioxidant owing to its strong reductant activity. In this study, we treated TM4 Sertoli cells with different doses of fluoride (4 ppm and 20 ppm) for different time periods (24 hours and 48 hours) and additionally with vitamin C (50 mu M), and then analyzed the activity of enzymes involved in antioxidant and steroidogenic systems. According to our results, fluoride inhibits testosterone biosynthesis by reducing the activities of 3 beta-HSD and 17 beta-HSD enzymes, which have roles in testosterone synthesis in TM4 Sertoli cells, and vitamin C has a protective role against the damage of fluoride. Fluoride was found to cause oxidative damage in TM4 Sertoli cells by reducing the amount and activities of glutathione and antioxidant enzymes (SOD, CAT, GPx, GST, gamma-GT), which function in the antioxidant system. A combination of fluoride and vitamin C was found to be protective against the damage by ROS and to cause an increase in the activities of enzymes in the intracellular antioxidant system. In conclusion, fluoride may result in harmful effects in TM4 Sertoli cells and vitamin C can be protective against these effects.",
Arsenic,1342673,New Generation Adsorbents for Water Treatment Abstract: ,
Arsenic,628315,"Effects of low dietary intake of methionine, choline or proteins on the biotransformation of arsenite in the rabbit Abstract: The effects of 6 weeks feeding with diets low in methionine, choline, or proteins on the biotransformation and retention of 76As-labelled arsenite (0.4 mg As/kg bw) in rabbits have been studied. All test diets caused a significant decrease in the urinary excretion of dimethyl[76As]-arsinic acid, the main metabolite of inorganic arsenic. This gave rise to an increased retention of arsenic in the tissues, especially liver and lung. The test diets also caused a specific increase of the arsenic concentration in liver microsomes. The results indicate that subjects with a poor nutritional status have a lower capacity of methylating and thereby detoxifying inorganic arsenic.",
Arsenic,2225283,"Determination of the oxidation states of metals and metalloids: An analytical review Abstract: The hazard of many heavy metals/metalloids in the soil depends on their oxidation state. The problem of determining the oxidation state has been solved due to the use of synchrotron radiation methods with the analysis of the X-ray absorption near-edge structure (XANES). The determination of the oxidation state is of special importance for some hazardous heavy elements (arsenic, antimony, selenium, chromium, uranium, and vanadium). The mobility and hazard of each of these elements depend on its oxidation state. The mobilities are higher at lower oxidation states of As, Cr, V, and Se and at higher oxidation states of Sb and U. The determination of the oxidation state of arsenic has allowed revealing its fixation features in the rhizosphere of hydrophytes. The known oxidation states of chromium and uranium are used for the retention of these elements on geochemical barriers. Different oxidation states have been established for vanadium displacing iron in goethite. The determination of the oxidation state of manganese in the rhizosphere and the photosynthetic apparatus of plants is of special importance for agricultural chemists.",
Arsenic,1345890,"Induction of heat shock proteins (HSPs) by sodium arsenite in cultured astrocytes and reduction of hydrogen peroxide-induced cell death Abstract: Induction of heat shock proteins (HSPs) protects cells from oxidative injury. Here Hsp72, Hsp27 and heme oxygenase-1 (HO-1) were induced in cultured rat astrocytes, and protection against oxidative stress was investigated. Astrocytes were treated with sodium arsenite (20-50 micro m) for 1 h, which was non-toxic to cells, 24 h later they were exposed to 400 micro m H2O2 for 1 h, and cell death was evaluated at different time points. Arsenite triggered strong induction of HSPs, which was prevented by 1 micro g/mL cycloheximide (CXH). H2O2 caused cell loss and increased cell death with features of apoptosis, i.e. TdT-mediated dUTP nick-end labelling (TUNEL) reaction and caspase-3 activation. These features were abrogated by pre-treatment with arsenite, which prevented cell loss and significantly reduced the number of dead cells. The protective effect of arsenite was not detected in the presence of CHX. Pre-treatment with arsenite increased protein kinase B (Akt) and extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation after H2O2. However, while Akt phosphorylation was prevented by CHX, Erk1/2 phosphorylation was further enhanced by CHX. The results show that transient arsenite pre-treatment induces Hsp72, HO-1 and, to a lesser extent, Hsp27; it reduces H2O2-induced astrocyte death; and it causes selective activation of Akt following H2O2. It is suggested that HSP expression at the time of H2O2 exposure protects astrocytes from oxidative injury and apoptotic cell death by means of pro-survival Akt.",
Arsenic,1016133,"Poultry litter incineration as a source of energy: Reviewing the potential for impacts on environmental health and justice Abstract: Legislation in North Carolina has mandated obtaining renewable energy from the incineration of poultry waste, resulting in proposals for three poultry-litter-fueled power plants statewide. This article summarizes environmental health and environmental justice issues associated with incineration of poultry waste for the generation of electric power. Emissions from poultry waste incineration include particulate matter, dioxins, arsenic, bioaerosols and other toxins; various components are associated with cardiovascular disease, cancer, respiratory illness, and other diseases. Industrial farm animal production tends to be concentrated in low-income, rural communities, where residents may be more vulnerable to air pollutants due to pre-existing diseases, other exposures and stressors, and poor access to medical services. These communities lack the political clout to prevent citing of polluting facilities or to pressure industry and government to follow and enforce regulations. Policies intended to reduce reliance on fossil fuels have the potential to increase environmental injustices and threats to environmental health.",
Arsenic,2149317,Transforming the Arsenic Crisis into an Economic Enterprise: Example from Indian Villages Abstract: ,
Arsenic,2149137,Bacteria and arsenic: An annotated selection of World Wide Web sites relevant to the topics in Environmental Microbiology Abstract: ,
Arsenic,1576391,"Examining the ecological paradox of the 'mycorrhizal-metal-hyperaccumulators' Abstract: This analysis identifies and attempts to resolve the paradox of combining plant hyperaccumulators and arbuscular mycorrhizal fungi (AMF) for the purpose of post-industrial bioremediation due to the divergence of their respective ecological and evolutionary stress-tolerance behaviors. The identification of a ‘dilemma of resource allocation’ associated with plant resources consumed in intrinsic (e.g. metabolic) vs. extrinsic (e.g. symbiotic) stress-tolerance mechanisms could provide a suitable evolutionary reasoning for the apparent dichotomy existing between the hyperaccumulators and AMF–plant life-history strategies. Ultimately, it is considered that any efforts toward integrating such biotechnology innovations into bioremediation strategies (e.g. ‘mycorrhizal–metal-hyperaccumulators’) should first explicitly consider their inherent environmental and (or) evolutionary contexts to avoid misleading and possibly even unproductive outcomes prior to incorporating these attributes as potential technological solutions.",
Arsenic,1032537,"Neoplastic transformation of BALB/3T3 cells by metals and the quest for induction of a metastatic phenotype Abstract: In the mouse embryo cell line BALB/3T3 Clone A31-1-1, dose-dependent morphologic neoplastic transformation was obtained with NaAsO2, Na2HAsO4, CdCl2, and K2CrO4. Cellular uptake was four fold higher for As3+ than for As5+, and As5- was metabolized to As3+ in cytosol. Cytotoxicity and transformation rates were four fold higher for As3+ than As5+, but when correlated to cellular As burden they were equivalent. As3+ appears responsible for the transforming activity. The foci transformed by metals (or by other carcinogens) gave rise to tumorigenic cell lines (sc sarcomas in nude mice), none of which, however, induced metastases when tested by sc or by iv injection in nude mice. Thus carcinogens change this aneuploid cell line from a preneoplastic stage to the expression of malignant growth but not of metastatic activity. Metastatic and type IV collagenolytic activities can be induced by transfection of the c-Ha-ras oncogene and inhibited by the Ad2-E1a gene (so far shown in other cell types). It remains to be seen whether metal or other carcinogens can induce the nonmetastatic phenotype to become metastatic. The molecular mechanisms of metal carcinogenesis, studied in cell culture systems, in combination with other factors or oncogenes, may reveal the effect of individual metal carcinogens on discrete steps of the complex process of carcinogenesis.",
Arsenic,1348538,"Agent Orange exposure, Vietnam War veterans, and the risk of prostate cancer Abstract: <strong>BACKGROUND: </strong>It has been demonstrated that Agent Orange exposure increases the risk of developing several soft tissue malignancies. Federally funded studies, now nearly a decade old, indicated that there was only a weak association between exposure and the subsequent development of prostate cancer. Because Vietnam War veterans are now entering their 60s, the authors reexamined this association by measuring the relative risk of prostate cancer among a cohort of men who were stratified as either exposed or unexposed to Agent Orange between the years 1962 and 1971 and who were followed during the interval between 1998 and 2006.<br /><br /><strong>METHODS: </strong>All Vietnam War era veterans who receive their care in the Northern California Veteran Affairs Health System were stratified as either exposed (n=6214) or unexposed (n=6930) to Agent Orange. Strata-specific incidence rates of prostate cancer (International Classification of Diseases, 9th Revision code 185.0) were calculated. Differences in patient and disease characteristics (age, race, smoking history, family history, body mass index, finasteride exposure, prebiopsy prostate-specific antigen (PSA) level, clinical and pathologic stage, and Gleason score) were assessed with chi-square tests, t tests, a Cox proportional hazards model, and multivariate logistic regression.<br /><br /><strong>RESULTS: </strong>Twice as many exposed men were identified with prostate cancer (239 vs 124 unexposed men, respectively; odds ratio [OR], 2.19; 95% confidence interval [95% CI], 1.75-2.75). This increased risk also was observed in a Cox proportional hazards model from the time of exposure to diagnosis (hazards ratio [HR], 2.87; 95% CI, 2.31-3.57). The mean time from exposure to diagnosis was 407 months. Agent Orange-exposed men were diagnosed at a younger age (59.7 years; 95% CI, 58.9-60.5 years) compared with unexposed men (62.2 years; 95% CI, 60.8-63.6 years), had a 2-fold increase in the proportion of Gleason scores 8 through 10 (21.8%; 95% CI, 16.5%-27%) compared with unexposed men (10.5%; 95% CI, 5%-15.9%), and were more likely to have metastatic disease at presentation than men who were not exposed (13.4%; 95% CI, 9%-17.7%) than unexposed men (4%; 95% CI, 0.5%-7.5%). In univariate analysis, distribution by race, smoking history, body mass index, finasteride exposure, clinical stage, and mean prebiopsy PSA were not statistically different. In a multivariate logistic regression model, Agent Orange was the most important predictor not only of developing prostate cancer but also of high-grade and metastatic disease on presentation.<br /><br /><strong>CONCLUSIONS: </strong>Individuals who were exposed to Agent Orange had an increased incidence of prostate cancer; developed the disease at a younger age, and had a more aggressive variant than their unexposed counterparts. Consideration should be made to classify this group of individuals as 'high risk,' just like men of African-American heritage and men with a family history of prostate cancer.",
Arsenic,1350459,"ANALYTICAL METHODS UTILIZING IMPREGNATED CHARCOAL AND ATOMIC ABSORPTION SPECTROPHOTOMETRY FOR DETERMINATION OF ARSENIC, SELENIUM, AND TELLURIUM IN ATMOSPHERIC AND BIOLOGICAL SAMPLES Abstract: ",
Arsenic,1349781,Field testing of CCA-treated Brazilian spotted gum Abstract: ,
Arsenic,1357516,"Influence of Organic and Inorganic Arsenicals on Glucose Uptake in Madin-Darby Canine Kidney (MDCK) Cells Abstract: The utilization of extracellular carbohydrates in the presence of arsenicals was evaluated in Madin-Darby-canine-kidney (MDCK) cells. Enzyme activity was assessed through addition of glucose to enzyme mixtures of hexokinase and glucose-6-phosphate-dehydrogenase, followed by addition of the arsenicals. Lactate-dehydrogenase activity was assayed also. Uptake studies were started with addition of labeled D-glucose and 2-deoxy-D-glucose along with at least one of the following: D-glucose, L-glucose, arsenite (1327533), or oxyphenylarsine. Cell viability, protein content, and potassium concentrations were assessed. Results revealed a stereospecific glucose uptake mechanism in MDCK cells. The uptake of D-glucose and 2-deoxy-D-glucose was inhibited by both organic and inorganic arsenic (7440382) species, suggesting impaired cellular hexose metabolism. From 0.5 to 1 millimole per cubic decimeter of arsenite and 5 to 30 micromole per cubic decimeter of oxyphenylarsine were required for half maximum inhibition. Oxyphenylarsine showed much more potent inhibitory activity than arsenite on D-glucose uptake. The difference was attributed to better accessibility of the organic compound to transport molecules on the cell membrane. The authors conclude that arsenical toxicity is associated with D-glucose transport but is independent of subsequent intracellular metabolism of hexose.",
Arsenic,1026534,"Amelioration of arsenic toxicity by L-Ascorbic acid in laboratory rat Abstract: A study so as to confirm the protective effects of L-ascorbic acid against inorganic arsenic (As23) toxicity was made in male Wistar rats. Multiphase observations made on iAs concentration in target organs viz. liver and kidney, liver function, histopathological changes, ultrastructural alterations, lipid peroxidation, oxidative stress and iAs-DNA interaction strongly favoured its ameliorative effects. These effects could mainly be attributed to its antioxidative property. It offers help in regeneration of GSH and alpha-tocopherol. The chelaticn of iAs by ascorbic acid has also been hypothesized. Inhibition of DNA damage by ascorbic acid in liver and kidney appears to be the most significant part of this study On the basis of these results, we conclude that administration of L-ascorbic acid to arsenic affected population may prevent the occurrence of fatal human diseases.",
Arsenic,478610,"Arsenic poisoning in Bangladesh: Spatial mitigation planning with GIS and public participation Abstract: A PPGIS (Public Participatory Geographical Information System) has recently been developed in combination with PRA (Participatory Rural Appraisal) and GIs (Geographical Information Systems) methodologies to milise GIs in the context of the needs of communities that are involved with, and affected by development programmes. The impact of arsenic poisoning in Bangladesh is 'tragic and painful' on patients' health and their social life what was described as the 'worse mass poisoning in human history' in a WHO report. Deep tubewell is said to be a source of arsenic-free safe drinking water and people are mainly interested in deep tubewell water rather than rainwater harvesting, dug-wells, and pond-sand-filters (PSF) approved by the BAMWSP (Bangladesh Arsenic Mitigation Water Supply Project). This paper mainly explores the application and suitability of GIs with local community participation in deep tubewell planning for arsenic mitigation. The relevant data for this study were collected from the field survey. The PRA methods were used to obtain social and resource information; while a GIs was used to organise, analyse, and display the information. Participants from three different focus-groups were asked to determine their 'own priorities' for spatial planning of deep tubewell for arsenic-free water. The study results valuable community perspectives on deep tubewell planning and reveals the suitability of PPGIS in spatial planning for arsenic mitigation with local community mapping overlay. The process of dialogue and preparation of mental mapping within each focus-group participants lead to enhance information about community needs of deep tubewell in the study area.",
Arsenic,1350925,"Urinary arsenic and malondialdehyde to identify the risk among susceptible populations exposed to coal-borne arsenic Abstract: Urinary malondialdehyde (MDA) is used to evaluate the lipid perox- idation and DNA damage caused by free radicals or reactive oxygen species (ROS). 119 urine samples were collected from villagers who lived in arsenic contaminated-coal burning villages, Guizhou Province, China, where chronic arsenicosis is prevalent. 30 samples were collected from villagers in nearby control villages where coal burning or other source of arsenic contamination is insignificant. The urinary MDA was analyzed by using a GLC-MS method. The recovery for MDA from spiked samples was about 100%. Both urinary arsenic and MDA levels were increased in all arsenic-exposed groups (<20 yr, 20-40 yr, >40 yr old). The elevations were the most significant in the young and female exposure groups, who are likely to spend longer time indoors, and hence are at a higher risk. Statistically the difference of the urinary MDA concentrations in the exposed groups was significantly higher than those in the control groups by gender and different age groups. Our results confirmed the existence of lipid peroxidation in these susceptible populations due to the induction of reactive oxygen species (ROS) by arsenic exposure. The risk of elevated levels of MDA in chronically arsenic-exposed individuals associated with arsenic carcinogenesis, mutagenesis and DNA damage will be discussed.",
Arsenic,2149168,"Removal of arsenic species from water by batch and column operations on bagasse fly ash Abstract: Bagasse fly ash (BFA, a sugar industrial waste) was used as low-cost adsorbent for the uptake of arsenate and arsenite species from water. The optimum conditions for the removal of both species of arsenic were as follows: pH 7.0, concentration 50.0 ?g/L, contact time 50.0 min, adsorbent dose 3.0 g/L, and temperature 20.0 °C, with 95.0 and 89.5 % removal of arsenate and arsenite, respectively. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherms were used to analyze the results. The results of these models indicated single-layer uniform adsorption on heterogeneous surface. Thermodynamic parameters, i.e., ?G°, ?H°, and ?S°, were also calculated. At 20.0 to 30.0 °C, the values of ?G° lie in the range of -4,722.75 to -4,878.82 and -4,308.80 to -4,451.73 while the values of ?H° and ?S° were -149.90 and -121.07, and 15.61 and 14.29 for arsenate and arsenite, respectively, indicating that adsorption is spontaneous and exothermic. Pseudo-first-order kinetics was followed. In column experiments, the adsorption decreased as the flow rate increased with the maximum removal of 98.9 and 95.6 % for arsenate and arsenite, respectively. The bed depth service time and Yoon and Nelson models were used to analyze the experimental data. The adsorption capacity (N o) of BFA on column was 3.65 and 2.98 mg/cm(3) for arsenate and arsenite, respectively. The developed system for the removal of arsenate and arsenite species is economic, rapid, and capable of working under natural conditions. It may be used for the removal of arsenic species from any contaminated water resources.",
Arsenic,2149274,Effect of sulphate nutrition on arsenic translocation and photosynthesis of rice seedlings Abstract: ,
Arsenic,1019860,"Development of a skin cancer prevention program Abstract: The Centers for Disease Control and Prevention (CDC) now categorizes skin cancer as epidemic. Nearly 90% of these deadly cancers start from sun exposure during the childhood years. This makes sun exposure in school-age children a serious public health risk, also one that school nurses can address. Solar radiation is now classified as a &quot;known human carcinogen,&quot; with ultraviolet rays joining the ranks of other known cancer-causing elements such as tobacco, arsenic, and radon. Sun exposure to unprotected skin results in painful burns, premature aging, cataracts, and weakened immune systems. School nurses can use the new CDC guidelines along with other local and state resources to develop a specific skin cancer prevention program for their schools. They are in a pivotal position to partner with students, parents, administrators, teachers, and coaches to reduce the occurrence of skin cancer in children. The article describes one high school's skin cancer prevention project.",
Arsenic,1372387,"Exposure Assessment of Children Exposed to Arsenic in an Urban Playlot Abstract: Background: In June 2001 local public health authorities closed an urban playlot due to a 10 ? 10 foot square hot spot of arsenic (As) contamination (>800 ppm). Methods: Health authorities conducted an 8-week exposure assessment that began 2 months after abatement that included exposure questionnaires, health assessments, spot (creatinine adjusted) urine As, and 24-hour urine As. Bioassays were analyzed using ICP-MS. Results: 216 children were evaluated (51 spot and 24-hour urine; 88 spot urine only; 87 24-hour urine only). Geometric mean age of the children was 6.89 years (range 2 months to 18 years); 53% male. None of the children reported any symptoms or demonstrated any signs of acute or chronic arsenicosis. Geometric mean 12.7 mcg/gCr of the spot urine samples had a range 0.35?87.17; geometric mean 8.5 mcg/L of the 24-urine samples had a range 7.5?101.0 (lowest detection limit = 15, 1/2 detection limit = 7.5). Conclusion: Children's exposure to As from CCA treated wood is currently an area of active public health investigation. Since urine assays were collected 2 months after abatement and no child had evidence of arsenicosis, these data most likely represent background levels of As burden in children living in urban housing developments. Normative data on As distributions in pediatric populations are sparse, and these data provide useful comparative data for other exposure assessment studies.",
Arsenic,1936035,"Increases of ferrous iron oxidation activity and arsenic stressed cell growth by overexpression of Cyc2 in Acidithiobacillus ferrooxidans ATCC19859 Abstract: Acidithiobacillus ferrooxidans plays an important role in bioleaching in reproducing the mineral oxidant of ferric iron (Fe(3+) ) by oxidization of ferrous iron (Fe(2+) ). The high-molecular-weight c-type cytochrome Cyc2 that is located in the external membrane is postulated as the first electron carrier in the Fe(2+) oxidation respiratory pathway of A. ferrooxidans. To increase ferrous iron oxidation activity, a recombinant plasmid pTCYC2 containing cyc2 gene under the control of Ptac promoter was constructed and transferred into A. ferrooxidans ATCC19859. The transcriptional level of cyc2 gene was increased by 2.63-fold and Cyc2 protein expression was observed in the recombinant strain compared with the control. The ferrous iron oxidation activity and the arsenic stressed cell growth of the recombinant strain were also elevated.",
Arsenic,1677623,"Bioavailability and ecotoxicity of arsenic species in solution culture and soil system: Implications to remediation Abstract: In this work, bioavailability and ecotoxicity of arsenite (As(III)) and arsenate (As(V)) species were compared between solution culture and soil system. Firstly, the adsorption of As(III) and As(V) was compared using a number of non-allophanic and allophanic soils. Secondly, the bioavailability and ecotoxicity were examined using germination, phytoavailability, earthworm, and soil microbial activity tests. Both As-spiked soils and As-contaminated sheep dip soils were used to test bioavailability and ecotoxicity. The sheep dip soil which contained predominantly As(V) species was subject to flooding to reduce As(V) to As(III) and then used along with the control treatment soil to compare the bioavailability between As species. Adsorption of As(V) was much higher than that of As(III), and the difference in adsorption between these two species was more pronounced in the allophanic than non-allophanic soils. In the solution culture, there was no significant difference in bioavailability and ecotoxicity, as measured by germination and phytoavailability tests, between these two As species. Whereas in the As-spiked soils, the bioavailability and ecotoxicity were higher for As(III) than As(V), and the difference was more pronounced in the allophanic than non-allophanic soils. Bioavailability of As increased with the flooding of the sheep dip soils which may be attributed to the reduction of As(V) to As(III) species. The results in this study have demonstrated that while in solution, the bioavailability and ecotoxicity do not vary between As(III) and As(V), in soils, the latter species is less bioavailable than the former species because As(V) is more strongly retained than As(III). Since the bioavailability and ecotoxicity of As depend on the nature of As species present in the environment, risk-based remediation approach should aim at controlling the dynamics of As transformation.",
Arsenic,1936087,"A large prospective study of risk factors for adenocarcinomas and malignant carcinoid tumors of the small intestine Abstract: <strong>PURPOSE: </strong>Small intestinal cancer is increasing in the U.S.A, yet little is known about its etiology. Our aim was to prospectively evaluate risk factors for this malignancy by the two main histologic subtypes (adenocarcinomas and carcinoids).<br /><br /><strong>METHODS: </strong>Hazard ratios and 95 % confidence intervals (CI) were estimated for all incident small intestinal cancers (n = 237), adenocarcinomas (n = 84), and malignant carcinoids (n = 124), by demographic and lifestyle factors among 498,376 men and women.<br /><br /><strong>RESULTS: </strong>Age was the only risk factor for adenocarcinomas (HR for ?65 vs. 50-55 years = 3.12, 95 % CI 1.33, 7.31). Age (HR for ?65 vs. 50-55 years = 3.31, 95 % CI 1.51, 7.28), male sex (HR = 1.44, 95 % CI 1.01, 2.05), body mass index (BMI, HR for ?35 vs. 18.5-&lt;25 kg/m(2) = 1.95, 95 % CI 1.06, 3.58), and current menopausal hormone therapy use (HR = 1.94, 95 % CI 1.07, 3.50) were positively associated with malignant carcinoids. A family history of any cancer or colorectal cancer (HR = 1.42, 95 % CI 0.99, 2.03; 1.61, 0.97, 2.65, respectively), or a personal history of colorectal polyps (HR = 1.51, 95 % CI 0.92, 2.46) produced elevated, but not statistically significant, risks for malignant carcinoids. Race, education, diabetes, smoking, physical activity, and alcohol intake were not associated with either histologic subtype.<br /><br /><strong>CONCLUSIONS: </strong>Risk factors differed according to cancer subtype; only age was associated with adenocarcinomas, whereas age, male sex, BMI, and menopausal hormone therapy use were positively associated with malignant carcinoids.",
Arsenic,1337566,"Knowledge building insights on biomarkers of arsenic toxicity to keratinocytes and melanocytes Abstract: Exposure to inorganic arsenic induces skin cancer and abnormal pigmentation in susceptible humans. High-throughput gene transcription assays such as DNA microarrays allow for the identification of biological pathways affected by arsenic that lead to initiation and progression of skin cancer and abnormal pigmentation. The overall purpose of the reported research was to determine knowledge building insights on biomarker genes for arsenic toxicity to human epidermal cells by integrating a collection of gene lists annotated with biological information. The information sets included toxicogenomics gene-chemical interaction; enzymes encoded in the human genome; enriched biological information associated with genes; environmentally relevant gene sequence variation; and effects of non-synonymous single nucleotide polymorphisms (SNPs) on protein function. Molecular network construction for arsenic upregulated genes TNFSF18 (tumor necrosis factor [ligand] superfamily member 18) and IL1R2 (interleukin 1 Receptor, type 2) revealed subnetwork interconnections to E2F4, an oncogenic transcription factor, predominantly expressed at the onset of keratinocyte differentiation. Visual analytics integration of gene information sources helped identify RAC1, a GTP binding protein, and TFRC, an iron uptake protein as prioritized arsenic-perturbed protein targets for biological processes leading to skin hyperpigmentation. RAC1 regulates the formation of dendrites that transfer melanin from melanocytes to neighboring keratinocytes. Increased melanocyte dendricity is correlated with hyperpigmentation. TFRC is a key determinant of the amount and location of iron in the epidermis. Aberrant TFRC expression could impair cutaneous iron metabolism leading to abnormal pigmentation seen in some humans exposed to arsenicals. The reported findings contribute to insights on how arsenic could impair the function of genes and biological pathways in epidermal cells. Finally, we developed visual analytics resources to facilitate further exploration of the information and knowledge building insights on arsenic toxicity to human epidermal keratinocytes and melanocytes.",1
Arsenic,577108,"Transcriptional changes associated with reduced spontaneous liver tumor incidence in mice chronically exposed to high dose arsenic Abstract: Exposure of male C3H mice in utero (from gestational days 8-18) to 85Â ppm sodium arsenite via the dams' drinking water has previously been shown to increase liver tumor incidence by 2 years of age. However, in our companion study (Ahlborn et al., 2009), continuous exposure to 85Â ppm sodium arsenic (from gestational day 8 to postnatal day 365) did not result in increased tumor incidence, but rather in a significant reduction (0% tumor incidence). The purpose of the present study was to examine the gene expression responses that may lead to the apparent protective effect of continuous arsenic exposure. Genes in many functional categories including cellular growth and proliferation, gene expression, cell death, oxidative stress, protein ubiquitination, and mitochondrial dysfunction were altered by continuous arsenic treatment. Many of these genes are known to be involved in liver cancer. One such gene associated with rodent hepatocarcinogenesis, Scd1, encodes stearoyl-CoA desaturase and was down-regulated by continuous arsenic treatment. An overlap between the genes in our study affected by continuous arsenic exposure and those from the literature affected by long-term caloric restriction suggests that reduction in the spontaneous tumor incidence under both conditions may involve similar gene pathways such as fatty acid metabolism, apoptosis, and stress response.",
Arsenic,749371,"Biological activity of inorganic arsenic and antimony reflects oxidation state in cultured human keratinocytes Abstract: Sodium arsenite is much more potent than sodium arsenate in producing adverse effects in animals and in cultured cells. Although arsenate may exhibit toxicity as a phosphate analogue, its potency in vivo appears to be enhanced by reduction to arsenite. To understand the relative importance of this reduction, which is critical in evaluating the responsiveness of cell culture models to the different oxidation states and thus to elucidating the mechanism of arsenic action, present work has correlated the extent of reduction with biological activity in human keratinocytes. The results show that at biologically relevant concentrations, arsenate reduction to appreciable levels required several days, helping rationalize a previous empirical observation that it was approximately one-third as potent as arsenite. The relatively low conversion rate also emphasizes a limitation of culture; arsenate was nearly as efficacious as arsenite, but the time required for it to reach maximal effect exceeded ordinary medium change intervals. In keratinocytes, an important role for purine nucleoside phosphorylase in the reduction could not be demonstrated, indicating that another pathway is dominant in this cell type. Methylation of inorganic arsenic, uptake of methylated forms, and their reduction were all very slow. These findings suggest that the reduced methylated forms have only a small contribution to skin carcinogenesis unless they are supplied through the circulation. In parallel experiments, trivalent antimony was similar to arsenite in potency and efficacy, whereas pentavalent antimony was virtually without biological effect. Conversion of antimony in the pentavalent to the trivalent oxidation state was not detectable in keratinocytes. These findings emphasize the importance of intracellular reduction of the metalloids for biological effects.",
Arsenic,1349678,"Skermanella stibiiresistens sp. nov., a highly antimony-resistant bacterium isolated from coal-mining soil, and emended description of the genius Skermanella Abstract: A Gram-negative, aerobic, motile, rod-shaped, antimony-resistant bacterium, designated strain SB22T, was isolated from soil of Jixi coal mine, China. The major cellular fatty acids (>5?%) were C18?:?1?7c (63.5?%), summed feature 2 (C14?:?0 3-OH and/or iso-C16?:?1 I, 10.8?%) and C16?:?0 (9.9?%). The major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and an unknown aminolipid. The genomic DNA G+C content was 69.6 mol% and Q-10 was the major respiratory quinone. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain SB22T was most closely related to Skermanella aerolata 5416T-32T (97.3?%), Skermanella parooensis ACM 2042T (95.8?%) and Skermanella xinjiangensis 10-1-101T (92.9?%). The DNA–DNA hybridization value between strain SB22T and S. aerolata KACC 11604T (?=?5416T-32T) was 43.3?%. On the basis of phenotypic, chemotaxonomic and phylogenetic characteristics of strain SB22T and related species, it is considered that the isolate represents a novel species of the genus Skermanella, for which the name Skermanella stibiiresistens sp. nov. is proposed. The type strain is SB22T (?=?CGMCC 1.10751T?=?KCTC 23364T). An emended description of the genus Skermanella is provided.",
Arsenic,2279029,"Thunbergia laurifolia extract minimizes the adverse effects of toxicants by regulating P-glycoprotein activity, CYP450, and lipid metabolism gene expression in HepG2 cells Abstract: Thunbergia laurifolia (TL) is widely used as an antidote in Thai traditional medicine against toxic substances such as alcohol, pesticides, arsenic, and strychnine. We found that the lyophilized form of TL in 80% ethanol possessed the antioxidant levels within the range 23,163.9 ± 1457.4 Trolox equivalents mM/kg dry mass and 899.8 ± 14.5 gallic acid equivalents mM/kg dry mass using the oxygen radical absorbance capacity assay and the Folin Ciocalteu phenol assay, respectively. TL extract (TLE) at a high dose (3000 mg/L) induced cytotoxicity according to the neutral red assay and the MTT assay. However, TLE doses of 800-3000 mg/L could reduce intracellular oxidative stress in a dose-dependent manner (P &lt; 0.05) using the dichlorodihydrofluorescein diacetate assay. TLE significantly enhanced the mRNA expression of CYP1A1, CYP1A2, CYP2B6, CYP3A4, and PPARg, but it significantly inhibited the mRNA expression of CYP3A7, CYP2D6, and CYP2E1 (P &lt; 0.05) by reverse transcription-polymerase chain reaction. Moreover, TLE could increase the activity of a multidrug transporter, P-glycoprotein, which accelerated the excretion of toxic substances from HepG2 cells. It is suggested that TLE may be beneficial for detoxification by reducing oxidative stress, minimizing toxicity by regulating the expression CYP450 mRNAs for suitable production of CYP450 isoenzymes, and increasing PPAR? mRNA expression and P-glycoprotein activity in HepG2 cells, thereby maintaining xenobiotic biotransformation balance.",
Arsenic,627308,"Concomitant administration of Moringa oleifera seed powder in the remediation of arsenic-induced oxidative stress in mouse Abstract: Contamination of ground water by arsenic has become a cause of global public health concern. In West Bengal, India, almost 6 million people are endemically exposed to inorganic arsenic by drinking heavily contaminated groundwater through hand-pumped tube wells. No safe, effective and specific preventive or therapeutic measures for treating arsenic poisoning are available. We recently reported that some of the herbal extracts possess properties effective in reducing arsenic concentration and in restoring some of the toxic effects of arsenic in animal models. Moringa oleifera Lamarack (English: Horseradish-tree, Drumstick-tree, Hindi: Saijan, Sanskrit: Shigru) belongs to the Moringaceae family, is generally known in the developing world as a vegetable, a medicinal plant and a source of vegetable oil. The objective of the present study was to determine whether Moringa oleifera (M. oleifera) seed powder could restore arsenic induced oxidative stress and reduce body arsenic burden. Exposure to arsenic (2.5 mg/kg, intraperitoneally for 6weeks) led to a significant increase in the levels of tissue reactive oxygen species (ROS), metallothionein (MT) and thiobarbituric acid reactive substance (TBARS) which were accompanied by a decrease in the activities in the antioxidant enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) in mice. Arsenic exposed mice also exhibited liver injury as reflected by reduced acid phosphatase (ACP), alkaline phosphatase (ALP) and aspartate aminotransferase (AST) activities and altered heme synthesis pathway as shown by inhibited blood delta-aminolevulinic acid dehydratase (delta-ALAD) activity. Co-administration of M. oleifera seed powder (250 and 500 mg/kg, orally) with arsenic significantly increased the activities of SOD, catalase, GPx with elevation in reduced GSH level in tissues (liver, kidney and brain). These changes were accompanied by approximately 57%, 64% and 17% decrease in blood ROS, liver metallothionein (MT) and lipid peroxidation respectively in animal co-administered with M. oleifera and arsenic. Another interesting observation has been the reduced uptake of arsenic in soft tissues (55% in blood, 65% in liver, 54% in kidneys and 34% in brain) following administration of M. oleifera seed powder (particularly at the dose of 500 mg/kg). It can thus be concluded from the present study that concomitant administration of M. oleifera seed powder with arsenic could significantly protect animals from oxidative stress and in reducing tissue arsenic concentration. Administration of M. oleifera seed powder thus could also be beneficial during chelation therapy with a thiol chelator.",
Arsenic,1677563,"Assessment of Toxic Metals and Phthalates in Children's Toys and Clays Abstract: Toxic metals and phthalates are introduced in the manufacturing of plastic toys and modeling clays. In Lebanon, inexpensive plastic toys and modeling clays (sold in dollar stores) are affordable and popular, and there is no legislation to monitor or regulate such toys. This study aimed to assess the quality of inexpensive plastic toys and modeling clays imported in Lebanon. Metal concentrations in toys, namely, zinc [not detectable (ND) to 3,708 ?g/g], copper (ND to 140), chromium (ND to 75 ?g/g), tin (ND to 39 ?g/g), and cadmium (Cd) (ND to 20 ?g/g), were lower than the European Union (EU) Directive limits, whereas lead (ND to 258 ?g/g) in 10 % of samples and antimony (Sb) (ND to 195 ?g/g) in 5 % of samples were greater than the EU limits. In modeling clays, most of the metals were lower than the EU Directive limits except for Cd and arsenic (As). Cd was detected in 83 % of samples, with a mean level of 9.1 ?g/g, which is far greater than the EU Directive limit (1.9 ?g/g). The As mean level of 4.5 ?g/g was greater than the EU limit (4.0 ?g/g) and was detected in 9 % of samples. Phthalic acid esters (PAEs) were found in 60 % of children's toys and 77 % of modeling clays. Phthalic acid butyl ester had the highest-level PAE encountered and was ?59.1 % in one type of clay. However, among children's toys, di(4-octyl) ester terephthalic acid was the highest encountered phthalate at a concentration of 25.7 %. The community survey indicated that 82 % of households purchase their toys from inexpensive shops and that only 17 % of parents were aware of the health hazard of such toys. Consequently, an intervention plan was proposed for the provision of safe toys to children.",
Arsenic,2347584,"Thiolates of arsenic(III), antimony(III), and bismuth(III) with DL-alpha-dihydrolipoic acid Abstract: Lipoic acid can be reduced to dihydrolipoic acid free of lipoic acid without using deoxygenated solvents. Dihydrolipoic acid reacted with phenylarsine oxide, As2O3, and AsCl3, SbCl3 but not Sb2O3, and Bi2O3, BiCl3, and Bi(NO3)(3)center dot 5H(2)O in various solvents giving thiolates. When the reactions were done in methanol, the HCl and HNO3 released caused esterification of the -COOH group. The reaction with As(III) compounds was sensitive to dioxygen, leading to production of lipoic acid derivatives as well, arsenite being particularly active for the autoxidation. Physical (H-1 NMR) and chemical [reactivity of &gt;M-Cl and &gt;Bi(NO3)] properties of the adducts are described. The six-membered dihydrolipoic acid complexes reacted with stoichiometric amounts of British Anti-Lewisite releasing the dihydrolipoic acid by forming the corresponding complexes of British Anti-Lewisite.",
Arsenic,1347795,"Evaluation of nutritional status of an edible grasshopper, Oxya Chinensis Formosana Abstract: This study was conducted to examine the nutritional status of the grasshopper (Oxya chinensis formosana, OCF) as human food, exploring it as an alternative edible resource. Analysis of free amino acid shows that there are various essential amino acids in addition to saturated and unsaturated fatty acids in OCF dried powder. Analysis of the mineral contents and vitamins of dried OCF indicates that it is rich in calcium, vitamin B6, and niacin. The heavy metal content of OCF recorded was low, making it safe for human consumption: OCF had plumbum at 0.01–0.03?mg/100?g, cadmium at 0.002–0.005?mg/100?g, arsenic at 0.07–0.17?mg/100?g, and mercury at 0.0003–0.0007?mg/100?g. In conclusion, given its high nutritive quality in terms of proteins and fats, coupled with lower heavy metal content, it would be recommended to use the grasshopper (OCF) as substitute to the traditional sources of protein.",
Arsenic,2149124,"Melanocytes and keratinocytes have distinct and shared responses to ultraviolet radiation and arsenic Abstract: The rise of melanoma incidence in the United States is a growing public health concern. A limited number of epidemiology studies suggest an association between arsenic levels and melanoma risk. Arsenic acts as a co-carcinogen with ultraviolet radiation (UVR) for the development of squamous cell carcinoma and proposed mechanisms include generation of oxidative stress by arsenic and UVR and inhibition of UVR-induced DNA repair by arsenic. In this study, we investigate similarities and differences in response to arsenic and UVR in keratinocytes and melanocytes. Normal melanocytes are markedly more resistant to UVR-induced cytotoxicity than normal keratinocytes, but both cell types are equally sensitive to arsenite. Melanocytes were more resistant to arsenite and UVR stimulation of superoxide production than keratinocytes, but the concentration of arsenite necessary to inhibit the activity of the DNA repair protein poly(ADP-ribose)polymerase and enhance retention of UVR-induced DNA damage was essentially equivalent in both cell types. These findings suggest that although melanocytes are less sensitive than keratinocytes to initial UVR-mediated DNA damage, both of these important target cells in the skin share a mechanism related to arsenic inhibition of DNA repair. These findings suggest that concurrent chronic arsenic exposure could promote retention of unrepaired DNA damage in melanocytes and act as a co-carcinogen in melanoma.",
Arsenic,1371836,"Response of MSMA-resistant and -susceptible common cocklebur (Xanthium strumarium) biotypes to cotton (Gossypium hirsutum) herbicides and cross-resistance to arsenicals and membrane disruptors Abstract: BIOSIS COPYRIGHT: BIOL ABS. Experiments were conducted to evaluate PRE and POST cotton herbicides for control of MSMA-resistant (R) and -susceptible (S) common cocklebur biotypes, and to determine potential cross-resistance of the R biotype to other arsenical and membrane disruptor herbicides. Cyanazine and clomazone applied PRE were the most effective herbicides for control of R populations. Lactofen or cyanazine in combination with MSMA controlled R and S biotypes better than fluometuron or pyritiobac combined with MSMA. MSMA-resistant common cocklebur was not cross-resistant to other arsenical herbicides. Significant differences in cellular electrolyte leakage and chlorophyll content of the treated leaf between biotypes were not evident for paraquat, acifluorfen, and MSMA. Nomenclature: Acifluorfen, 5-(2-chloro-4-(trifluoromethyl)phenoxy)-2-nitrobenzoic acid; clomazone, 2-((2-chlorophenyl)methyl)-4,4-dimethyl-3-isoxazolidinone; cyanazine, 2-((4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl)amino)-2",
Arsenic,8693,"Levels of arsenic in Indian opium eaters Abstract: Intake of opium is very common in India. The contraband material is generally contaminated with arsenic. Most often opium eaters present with neuropathy and hepatomegaly. Arsenic was estimated in serum, urine, nails and hair of opium eaters with and without neuropathy. Arsenic was also estimated in various opium samples. Arsenic was significantly higher in serum, urine, nails and hair of opium addicts when compared to controls. The opium samples analysed showed varyingly high amounts of arsenic.",
Arsenic,656830,"Differential response of cellular antioxidant mechanism of liver and kidney to arsenic exposure and its relation to dietary protein deficiency Abstract: The effect on antioxidant defense system of liver and kidney of sub-acute i.p. exposure to sodium arsenite (3.33 mg/kg b.w. per day) for 14 days was studied in male Wistar rats fed on an adequate (18%) or a low (6%) protein diet. Following arsenic treatment, liver showed significantly enhanced concentration of glutathione and increased activities of glutathione reductase and glutathione-S-transferase on either of the dietary protein levels. Liver glutathione peroxidase and glucose-6-phosphate dehydrogenase activities increased significantly on an adequate protein diet while glutathione peroxidase activity decreased significantly on a low-protein diet. Lipid peroxidation and superoxide dismutase activity of liver remained unaltered on either of the dietary protein levels. On the other hand, kidney of arsenic-treated rats receiving either of the dietary protein levels showed significantly increased lipid peroxidation and decreased superoxide dismutase and catalase activities. Kidney glutathione content and glutathione reductase activity remained unaltered while glutathione peroxidase activity increased and glutathione-S-transferase activity decreased significantly on a low-protein diet following exposure to arsenic. On an adequate protein diet glucose-6-phosphate dehydrogenase activity in kidney, however, became significantly elevated following arsenic treatment. In Wistar rats, after 14 days of treatment with 3.33 mg As/kg b.w. i.p. the kidney seemed to be more sensitive to arsenic, and liver appears to be protected more by some of the antioxidant components, such as, glutathione, glutathione-S-transferase and glucose-6-phosphate dehydrogenase. It appears that low-protein diet influences the response of some of the cellular protective components against arsenic insult but does not lead to unique findings.",
Arsenic,8489,"Absence of arsenite mutagenicity in E coli and Chinese hamster cells Abstract: Because exposure to compounds of arsenic has been implicated as a cause of cancer, an investigation of the mutagenicity of sodium aresenite in E coli and in Chinese hamster cells was performed. In the E coli system, Trp revertants were not induced by arsenite in a variety of experimental protocols including spot tests, treat and plate protocols, and fluctuation tests. The mutator effect of a tif-1 strain was partially blocked by arsenite. Arsenite did not cause the induction of prophage. In Chinese hamster cells, arsenite did not induce ouabain-resistant mutants or thioguanine-resistant mutants. We conclude that arsenite is not mutagenic to E coli or to Chinese hamster cells. When added to the plating medium, arsenite can act as an anti-mutagen by inhibition of induction of the error-prone SOS repair system in E coli.",
Arsenic,1343598,"Thermal response in murine L929 cells lacking alpha B-crystallin expression and alpha B-crystallin expressing L929 transfectants Abstract: We investigated the role of alpha B-crystallin expression in the development of thermotolerance in murine L929 cells. An initial heat-shock of 10 min at 45 degrees C induced thermotolerance in these cells to a heat challenge at 45 degrees C administered 24 h later. The thermotolerance ratio at 10(-1) isosurvival was 1.7. Expression of alpha B-crystallin gene was not detected during the 24 h incubation at 37 degrees C following heat shock by either northern or western blots. In contrast, inducible HSP70 synthesis was observed during this time period. Thus, this cell line provided an unique system in which to examine the effects of transfected alpha B-crystallin on thermoresistance and thermotolerance. Cells stably transfected with alpha B-crystallin under the control of an inducible promoter did not show a significant increase in the ability to develop thermotolerance. However, a stably transfected L929 clone expressing high levels of constitutive alpha B-crystallin exhibited an approximately 50% increase in thermal resistance over parental and control cells. Though expression of alpha B-crystallin is not requisite for the development of thermotolerance in L929 cells, overexpression of transfected alpha B-crystallin can contribute to increased thermoresistance.",
Arsenic,2343529,"Toenail metal concentration as a biomarker of occupational welding fume exposure Abstract: In populations exposed to heavy metals, there are few biomarkers that capture intermediate exposure windows. We sought to determine the correlation between toenail metal concentrations and prior 12-month work activity in welders with variable, metal-rich, welding fume exposures. Forty-eight participants, recruited through a local union, provided 69 sets of toenail clippings. Union-supplied and worker-verified personal work histories were used to quantify hours welded and respirator use. Toenail samples were digested and analyzed for lead (Pb), manganese (Mn), cadmium (Cd), nickel (Ni), and arsenic (As) using ICP-MS. Spearman correlation coefficients were used to examine the correlation between toenail metal concentrations. Using mixed models to account for multiple participation times, we divided hours welded into three-month intervals and examined how weld hours correlated with log-transformed toenail Pb, Mn, Cd, Ni, and As concentrations. Highest concentrations were found for Ni, followed by Mn, Pb and As, and Cd. All the metals were significantly correlated with one another (rho range = 0.28–0.51), with the exception of Ni and As (rho = 0.20, p = 0.17). Using mixed models adjusted for age, respirator use, smoking status, and BMI, we found that Mn was associated with weld hours 7–9 months prior to clipping (p = 0.003), Pb was associated with weld hours 10–12 months prior to clipping (p = 0.03) and over the entire year (p = 0.04). Cd was associated with weld hours 10–12 months prior to clipping (p = 0.05), and also with the previous year's total hours welded (p = 0.02). The association between Ni and weld hours 7–9 months prior to clipping approached significance (p = 0.06). Toenail metal concentrations were not associated with the long-term exposure metric, years as a welder. Results suggest Mn, Pb, and Cd may have particular windows of relevant exposure that reflect work activity. In a population with variable exposure, toenails may serve as useful biomarkers for occupational metal fume exposures to Mn, Pb, and Cd during distinct periods over the year prior to sample collection.",
Arsenic,2229945,"Arsenate adsorption onto iron oxide amended rice husk char Abstract: In this study, rice husks were charred at 550°C in a partially sealed ceramic vessel for 30 minutes to create a high specific surface area (SSA) rice husk char (RHC). The RHC was then amended with iron oxides using dissolved ferric nitrate, Fe(NO3)3 ? 9H2O, to provide a surface chemistry conducive to arsenic adsorption. The 550°C iron oxide amended rice husk char's (550 IOA-RHC's) SSA was nearly 2.5 orders of magnitude higher and the arsenate adsorptive level was nearly 2 orders of magnitude higher than those reported for iron oxide amended sand, thus indicating a positive relationship between post-amendment SSA and arsenate adsorptive levels. Rice husks were then charred at temperatures ranging from 450°C to 1050°C to create an even higher SSA material, which might further increase arsenate adsorptive levels. The 950°C RHC was chosen for amendment due to its high SSA and feasibility of being produced in the field. Once amended, the 950°C iron oxide amended rice husk char (950 IOA-RHC) improved the arsenate adsorption capacity by thus confirming a positive relationship, though not a linear relationship, between post-amendment SSA and arsenic adsorptive capacity. Further study demonstrated that post-amendment mesoporous volume and mesoporous surface area appear to be better indicators of arsenic adsorptive capacity than SSA or iron content.",
Arsenic,656681,"mot-2-Mediated cross talk between nuclear factor-B and p53 is involved in arsenite-induced tumorigenesis of human embryo lung fibroblast cells Abstract: BACKGROUND: Inactivation of p53 is involved in arsenite-induced tumorigenesis; however, the molecular mechanisms remain poorly understood. OBJECTIVE: We investigated the molecular mechanisms underlying the inactivation of p53 and neoplastic transformation induced by arsenite in human embryo lung fibroblast (HELF) cells. METHODS: Anchorage-independent growth assays were performed, and tumorigenicity in intact animals was assessed to confirm arsenite-induced neoplastic transformation. We determined the levels and functions of p53, nuclear factor-kappa B (NF-B; a key transcriptional regulator), and mot-2 (a p53 inhibitor) and their relationships in arsenite-induced transformed HELF cells by two-dimensional electrophoresis, reverse-transcriptase polymerase chain reaction, Western blot, immunofluorescence, and co-immunoprecipitation assays. RESULTS: Exposure of HELF cells to low levels of arsenite increased their proliferation rate and anchorage-independent growth and disrupted normal contact inhibition. When introduced into nude mice, transformed cells were tumorigenic. We used proteomic analysis to identify proteins with altered expression between untreated and arsenite-exposed cells. We found decreased expression of NF-B repressing factor (NKRF; an inhibitor of NF-B-mediated gene transcription), increased expression of mot-2, and increased activation of NF-B. Changes in cells exposed to 1.0 microM arsenite were more marked than changes in cells exposed to 0.5 or 2.0 microM arsenite. Inactivation of NF-B prevented malignant transformation induced by 1.0 microM arsenite. Moreover, we also identified a mechanism whereby NF-B regulated p53. Specifically, activation of NF-B up-regulated mot-2 expression, which prevented nuclear translocation of p53 and switched the binding preference of the p53 and NF-B coactivator CBP [cyclic AMP-responsive element binding protein (CREB) binding protein] from p53 to NF-B. CONCLUSIONS: mot-2-mediated cross talk between NF-B and p53 appears to be involved in arsenite-induced tumorigenesis of HELF cells.",
Arsenic,1339822,"Poly (lactide-co-glycolide) encapsulated extract of Phytolacca decandra demonstrates better intervention against induced lung adenocarcinoma in mice and on A549 cells Abstract: We tested relative efficacy of the extract of Phytolacca decandra (PD) and its PLGA nano-encapsulated form (NPD) in mice intoxicated with benzo[a]pyrene (BaP) (25 mg/kg b.w.) plus sodium-arsenite (SA) (10 mg/kg b.w.) and on A549 lung cancer cells in vitro. We characterized nanoparticles by physico-chemical and morphological studies using dynamic light scattering, scanning electron and atomic force microscopies. We also conducted FTIR and (1)H NMR studies to determine if NPD had a co-polymeric nature and analyzed drug-DNA interaction through circular dichroism spectra (CD) and melting temperature profiles (T(m)) taking calf thymus DNA as target. An oral dose of 0.3mg/kg b.w. for NPD and 30 mg/kg b.w. for PD in mice showed chemopreventive effects in regard to DNA fragmentation, comet tail length and toxicity biomarkers like ROS generation, NF??, p53, PARP, CYP1A1 and caspase 3. NPD showed greater effects than that by PD. Results of in vivo studies showed similar effects on A549 in regard to cell viability, DAPI and PI staining, Comet tail length, DNA fragmentation. To further confirm the biological molecule present in PD we analyzed its chromatographic fraction through mass spectroscopy, NMR and FT-IR studies and characterized it to be a tri-terpenoid, a derivative of betulinic acid with a molecular formula C(30)H(46)O(2.) Thus, overall results suggest that nano-encapsulation of PD (NPD) increases drug bioavailability and thereby has a better chemo-preventive action against lung cancer in vivo and on A549 cells in vitro than that of PD.",
Arsenic,495273,"Mitochondrial damage mediates genotoxicity of arsenic in mammalian cells Abstract: Arsenic is an important environmental carcinogen that affects millions of people worldwide through contaminated water supplies. For decades, arsenic was considered a nongenotoxic carcinogen. Using the highly sensitive A(L) mutation assay, we previously showed that arsenic is, indeed, a potent gene and chromosomal mutagen and that its effects are mediated through the induction of reactive oxygen species. However, the origin of these radicals and the pathways involved are not known. Here we show that mitochondrial damage plays a crucial role in arsenic mutagenicity. Treatment of enucleated cells with arsenic followed by rescue fusion with karyoplasts from controls resulted in significant mutant induction. In contrast, treatment of mitochondrial DNA-depleted (rho(0)) cells produced few or no mutations. Mitochondrial damage can lead to the release of superoxide anions, which then react with nitric oxide to produce the highly reactive peroxynitrites. The mutagenic damage was dampened by the nitric oxide synthase inhibitor, N-G-methyl-L-arginine. These data illustrate that mitochondria are a primary target in arsenic-induced genotoxic response and that a better understanding of the mutagenic/carcinogenic mechanism of arsenic should provide a basis for better interventional approach in both treatment and prevention of arsenic-induced cancer.",
Arsenic,2149261,"Assessing the bioavailability and risk from metal-contaminated soils and dusts Abstract: Exposure to contaminated soil and dust is an important pathway in human health risk assessment. Physical and chemical characteristics and biological factors determine the bioaccessibility/bioavailability of soil and dust contaminants. Within a single sample, contamination may arise from multiple sources of toxic elements that may exist as different species that impact bioavailability. In turn, the bioaccessibility/bioavailability of soil and dust contaminants directly impacts human health risk. Research efforts focusing on development and application of in vitro and in vivo methods to measure the bioaccessibility/bioavailability of metal-contaminated soils have advanced in recent years. The objective of this workshop was to focus on developments in assessing the bioaccessibility/bioavailability of arsenic-contaminated soils, metals' contamination in urban Canadian residences and potential children's exposures to toxic elements in house dust, an urban community-based study (i.e., West Oakland Residential Lead Assessment), bioavailability studies of soil cadmium, chromium, nickel, and mercury and human exposures to contaminated Brownfield soils. These presentations covered issues related to human health and bioavailability along with the most recent studies on community participation in assessing metals' contamination, studies of exposures to residential contamination, and in vitro and in vivo methods development for assessing the bioaccessibility/bioavailability of metals in soils and dusts.",
Arsenic,710866,"Association between arsenic exposure from drinking water and proteinuria: Results from the Health Effects of Arsenic Longitudinal Study Abstract: BACKGROUND: Proteinuria has been recognized as a marker for an increased risk of chronic renal disease. It is unclear whether arsenic (As) exposure from drinking water is associated with proteinuria. METHODS: We evaluated the association between As exposure from drinking water and proteinuria in 11?122 participants in the Health Effects of Arsenic Longitudinal Study (HEALS). Proteinuria was detected by urinary dipstick tests at baseline and at 2-year intervals. As exposure variables included baseline well As and changes in urinary As during follow-up modelled as time-dependent variables in the analyses. RESULTS: At baseline, well As was positively related to prevalence of proteinuria; prevalence odds ratios (PORs) for proteinuria in increasing quintiles of well As (?7, 8-39, 40-91, 92-179 and 180-864?µg/l) were 1.00 (ref), POR 0.99 [95% confidence interval (CI) 0.77-1.27], POR 1.23 (95% CI 0.97-1.57), POR 1.50 (95% CI 1.18-1.89) and POR 1.59 (95% CI 1.26-2.00) (P for trend <0.01). Hazard ratios for incidence of proteinuria were POR 0.83 (95% CI 0.67-1.03) and POR 0.91 (95% CI 0.74-1.12) for participants with a decreasing level of >70 and 17-70?µg/l in urinary As over time, respectively, and were POR 1.17 (95% CI 0.97-1.42) and POR 1.42 (95% CI 1.16-1.73) for participants with an increasing level of 16-68 and >68?µg/l in urinary As over time, respectively, compared with the group with relatively little changes in urinary As as the reference group (urinary As -16 to 15 µg/l). CONCLUSION: The findings suggest that there are adverse effects of As exposure on the risk of proteinuria and the effects are modifiable by recent changes in As exposure.",
Arsenic,626989,"Arsenic and cancer Abstract: Palmar and plantar keratoses developed in seven patients many years after ingeston of trivalent inorganic arsenic. Six had basal cell carcinoma (superficial multicentric type in five), carcinoma &quot;in situ&quot; or squamous cell carcinoma of the skin. Two had systemic carcinoma--one, bilateral breast adenocarcinoma and one, carcinoma of the colon. From these observations and from the findings of a review of the literature, there seems no question that long-term arsenic ingestion can cause palmar and plantar keratoses and skin cancer, particularly basal cell carcinoma of the superficial multicentric type, usually on the torso. It is suspected but not proved to cause other cancers. Although over the last 50 years general exposure to arsenic has greatly decreased, particularly that from insecticides, this element is still found occasionally in drinking water (naturally or as a smelter byproduct), in certain foods and in cigarette smoke.",
Arsenic,1016641,"Effect of arsenic on benzo[a]pyrene DNA adduct levels in mouse skin and lung Abstract: Concomitant exposures to arsenic and polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (BaP) are widespread. While BaP acts by binding to and inducing mutations in critical sites on DNA, the mechanism(s) of arsenic carcinogenesis remains unknown. Data from epidemiological studies of arsenic copper smelter workers and arsenic ingestion in drinking water suggest a positive interaction for arsenic exposure and smoking and lung cancer. A previous in vitro study showed that arsenic potentiated the formation of DNA adducts at low doses of BaP and arsenic. The present study was conducted to test the effect of arsenic on BaP-DNA adduct formation in vivo. We hypothesized that arsenic co-treatment would significantly increase BaP adduct levels in C57BL/6 mouse target organs: skin and lung. Treatment groups were: five mice, -BaP/-arsenic; five mice, -BaP/+arsenic; 15 mice, +BaP/-arsenic; 15 mice, +BaP/+arsenic. Mice in the appropriate groups were provided sodium arsenite in drinking water (2.1 mg/l), ad libitum, for 13 days (starting 9 days before BaP treatment), and 200 nmol BaP/25 ml acetone (or acetone alone) was applied topically, once per day for 4 days. DNA was extracted from skin and lung and assayed by (32)P-postlabeling. Statistical comparisons were made using independent t-tests (unequal variances assumed). BaP-DNA adduct levels in the +BaP groups were significantly higher than -BaP controls. Arsenic co-treatment increased average BaP adduct levels in both lung and skin; the increase was statistically significant in the lung (P = 0.038). BaP adduct levels in the skin of individual animals were positively related to skin arsenic concentrations. These results corroborate our in vitro findings and provide a tentative explanation for arsenic and PAH interactions in lung carcinogenesis.",
Arsenic,656930,"Aquaglyceroporins are involved in uptake of arsenite into murine gastrointestinal tissues Abstract: Aquaglyceroporins (AQGPs) are members of aquaporin (AQP) family and belong to a subgroup of this water channel family; they are transmembrane proteins that transport water as well as glycerol and other solutes of small molecules. Recent studies have also identified that AQGPs are important transporters of trivalent metalloid in some mammalian cells. However, the uptake routes of arsenite in mammals are still less defined. In this study, to understand the routes of arsenite intake in mammals, mice were treated with Hg(II), glycerol, and As(III) and uptake of As(III) into the gastrointestinal tissues was measured. The level of inorganic arsenic (iAs) in gastrointestinal tissues after As(III) stimulation was much higher than Hg(II) +As(III) or glycerol+As(III) group. RT-PCR results showed that AQGPs were extensively expressed in gastrointestinal tissues of mice. We also treated Caco-2 cells with Hg(II) and As(III); the level of iAs in a group treated with Hg(II)+As(III) decreased compared with As(III)-treated group. Our results suggested that AQGPs could be important transporters in arsenite uptake into gastrointestinal tissues of mice, but more data are need to prove if AQGPs is the only pathway involved in As transport in mammals or just one of them.",
Arsenic,1519016,"Nutritional and neutraceutical composition of five wild culinary-medicinal species of genus pleurotus (higher basidiomycetes) from northwest India Abstract: Five wild culinary-medicinal species of genus Pleurotus (Fr.) P. Kumm. (P. floridanus Singer, P. pulmonarius (Fr.) Quél., P. sapidus Quél., P. cystidiosus O.K. Miller, and P. sajor-caju (Fr.) Singer), collected from different localities of Northwest India, were studied for their nutritional and nutraceutical composition. Composition analysis of nutrients involved determining proteins, fats, ash, fiber, and carbohydrates using standard biochemical techniques. Minerals were estimated by an atomic absorption spectrophotometer and toxic metals were determined by the Reinsch test method. The analysis of nutraceuticals included determination of sugars by high-performance liquid chromatography, fatty acids by gas chromatography, and antioxidants such as ?-carotene, lycopene, and total phenolic compounds with methanolic extract using a colorimetric assay. In the samples analyzed, carbohydrates dominated over protein and other macronutrients. Carbohydrates ranged from 85.86 to 88.38%, protein 0.98 to 2.17%, crude fat 0.62 to 0.84%, crude fibers 2.76 to 3.12%, and ash content 1.03 to 2.20%. Macro- and microminerals (calcium, magnesium, sodium, potassium, copper, zinc, and iron) also were found in substantial amount, whereas toxic metals (lead, silver, arsenic, mercury, and antimony) were not detected. Three main sugars-sucrose (0.338-2.011%), glucose (0.553-0.791%), and xylose (0.01%)-were detected. Among fatty acids, monounsaturated fatty (37.17-68.29%) acids were documented in a higher proportion than saturated fatty acids (26.07-47.77%). In terms of antioxidant composition, all species contained ascorbic acid, phenols, carotene, and lycopene. Ascorbic acid content ranged from 0.46 to 0.49 mg/100 g, total phenolic compounds ranged from 6.76 to 16.92 mg/100 g of gallic acid, ?-carotene ranged from 0.134 to 0.221 ?g/100 g, and lycopene from 0.055 to 0 .075 ?g/100 g.",
Arsenic,2337181,"Cytotoxicity and physical properties of tricalcium silicate-based endodontic materials Abstract: <strong>OBJECTIVES: </strong>The aim of this study was to evaluate the cytotoxicity, setting time and compressive strength of MTA and two novel tricalcium silicate-based endodontic materials, Bioaggregate (BA) and Biodentine (BD).<br /><br /><strong>MATERIALS AND METHODS: </strong>Cytotoxicity was evaluated by using a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide (XTT) assay. Measurements of 9 heavy metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc) were performed by inductively coupled plasma-mass spectrometry (ICP-MS) of leachates obtained by soaking the materials in distilled water. Setting time and compressive strength tests were performed following ISO requirements.<br /><br /><strong>RESULTS: </strong>BA had comparable cell viability to MTA, whereas the cell viability of BD was significantly lower than that of MTA. The ICP-MS analysis revealed that BD released significantly higher amount of 5 heavy metals (arsenic, copper, iron, manganese, and zinc) than MTA and BA. The setting time of BD was significantly shorter than that of MTA and BA, and the compressive strength of BA was significantly lower than that of MTA and BD.<br /><br /><strong>CONCLUSIONS: </strong>BA and BD were biocompatible, and they did not show any cytotoxic effects on human periodontal ligament fibroblasts. BA showed comparable cytotoxicity to MTA but inferior physical properties. BD had somewhat higher cytotoxicity but superior physical properties than MTA.",
Arsenic,1347786,"Effects of arsenic on osmoregulation in the tilapia Oreochromis mossambicus reared in seawater Abstract: The effects of arsenic (As2O3) on plasma osmolarity, Na and K concentrations, the activity of gill Na-K-ATPase, and on the ultrastructure of gill chloride cells were compared between seawater tilapia (Oreochromis mossambicus) and freshwater tilapia in the Institute of Zoology, Academia Sinica, between 1989 and 1991. Arsenic was found to be more lethal in seawater tilapia (96 h LC50 (median lethal concentration): 26.5 ppm) than in freshwater ones (71.7 ppm). No significant effect was found plasma ion concentrations and osmolarity, enzyme activity or the ultrastructure of chloride cells in freshwater tilapia after 96 h exposure to 70 ppm arsenic. In contrast, 96 h exposure to 15 ppm arsenic caused evident effects in seawater tilapia: an increase in plasma osmolarity and activity of gill Na-K-ATPase, as well as better development of the chloride cell tubular system. These data suggest that the lethal effect of arsenic may be partially attributed to a hydromineral disturbance in seawater tilapia, but in freshwater tilapia arsenic perhaps causes destruction in some physiological mechanisms other than osmoregulation. The activation of gill Na?K-ATPase and chloride cells in seawater tilapia appears to indicate an adaptation in the osmoregulatory mechanism to arsenic exposure, i.e., to enhance secreting ions or arsenic in the gills.",
Arsenic,1070349,"Toxicity of so-called edible hijiki seaweed (Sargassum fusiforme) containing inorganic arsenic Abstract: The UK Food Standards Agency and its counterparts in other countries have warned consumers not to eat hijiki (Sargassum fusiforme; synonym Hizikia fusiformis), a Sargasso seaweed, because it contains large amounts of inorganic arsenic. We investigated dietary exposure of hijiki in weaning male F344/N rats fed an AIN-93G diet supplemented with 3% (w/w) hijiki powder for 7weeks, compared with those fed only an AIN-93G diet. Body weight, body temperature, blood and tissue arsenic concentrations, plasma biochemistry and hematological parameters were measured. We found that feeding rats a 3% hijiki diet led to a marked accumulation of arsenic in blood and tissues, and evoked a high body temperature and abnormal blood biochemistry including elevated plasma alkaline phosphatase activity and inorganic phosphorus, consistent with arsenic poisoning. These findings should prompt further investigations to identify the health hazards related to consumption of hijiki and related Sargassum species in humans.",
Arsenic,628568,"Urinary arsenic speciation and porphyrins in C57Bl/6J mice chronically exposed to low doses of sodium arsenate Abstract: Arsenic has been classified as a human carcinogen based on epidemiological data however the mechanism of its carcinogenicity is still unclear. Urinary biomarkers for chronic arsenic exposure would be valuable as an early warning indicator for timely interventions. In this study, young female C57Bl/6J mice were given drinking water containing 0, 100, 250 and 500 microg Asv/L as sodium arsenate ad libitum for 12 months. Urine was collected bimonthly for urinary arsenic methylation assay and porphyrin analysis. All detectable arsenic species showed strong linear correlation with administered dosage and the arsenic methylation patterns were similar in all three treatment groups. No significant changes of methylation patterns were observed over time for either the control or test groups. Urinary coproporphyrin III was significantly increased in the 8th month in 250 and 500 microg/L groups and remained significantly dose-related after 10 and 12 months. Coproporphyrin I also showed a significant dose-response relationship after 12 months. Our results confirm that urinary arsenic is a useful biomarker for internal dose. The alteration of porphyrin profile suggests that arsenic can affect the heme metabolism and this may occur prior to the onset of arsenic induced carcinogenesis.",
Arsenic,458109,"Toxicologic evaluation of licorice extract as a cigarette ingredient Abstract: Licorice extract (block, powder or liquid) may be applied to cigarette tobacco at levels of about 1-4% to enhance and harmonize the flavor characteristics of smoke, improve moisture holding characteristics of tobacco, and act as a surface active agent for ingredient application. Neat material pyrolysis studies, and smoke chemistry and biological activity studies (bacterial mutagenicity, cytotoxicity, micronucleus, and sub-chronic inhalation) with mainstream smoke, or mainstream smoke preparations from cigarettes containing various target levels (1.5-12%) of the licorice extracts were performed to provide data for an assessment of the use of licorice extract as a cigarette tobacco ingredient. At simulated tobacco burning temperatures up to 900 degrees C all forms of neat licorice extract pyrolyzed extensively, yielding small amounts of benzene, toluene, phenol and acetaldehyde with no indication that licorice extracts would transfer intact to mainstream smoke. As a single ingredient added to cigarette tobacco, block licorice extract at a target level of 12.5% increased smoke constituents including selected PAH, arsenic, lead, phenol and formaldehyde (on a TPM basis), while licorice extract powder (target level of 8% tobacco) increased select PAH, phenol and formaldehyde (on a TPM basis). Lower target application levels (including typical application levels) of block, powder or liquid licorice extract did not significantly alter the smoke chemistry profile. Biological tests indicated no relevant difference in the genotoxic or cytotoxic potential of either mainstream smoke (or smoke preparations) from cigarettes with added licorice extracts compared to control cigarettes. In subchronic 90-day rat inhalation studies, the mainstream smoke from cigarettes with 12.5% added block and 8% added powder licorice extract contained higher formaldehyde concentrations compared to control cigarette smoke. Female rats in the 12.5% block licorice extract exposure group displayed an increased incidence and severity of epithelial hyperplasia in the nose (level 2), with no relevant respiratory tract changes in the 8% powder licorice extract exposed rats. At the lower licorice extract application levels (1.25-5%), there was no indication of increased formaldehyde concentration in the smoke atmosphere and no relevant changes in respiratory tract tissues. Mineralcorticoid-like effects which have been associated with excess licorice ingestion were not found in any of the smoke inhalation studies. The results of these studies with various forms of licorice extract applied to cigarette tobacco suggest that licorice extract to cigarette tobacco at levels of <= 5% does not discernibly alter the smoke chemistry or biological effects normally associated with mainstream cigarette smoke.",
Arsenic,2347698,"Increase of As release and phytotoxicity to rice seedlings in As-contaminated paddy soils by Si fertilizer application Abstract: Silicon (Si) was shown to be able to reduce arsenic (As) uptake by rice in hydroponic culture or in low As soils using high Si application rates. However, the effect of Si application on As uptake of rice grown in As-contaminated soils using Si fertilizer recommendation rate has not been investigated. In this study, the effect of Si application using Si fertilizer recommendation rate on As release and phytotoxicity in soils with different properties and contents of As was examined. The results show that the concentrations of As in soil solutions increased after Si applications due to competitive adsorption between As and Si on soil solids and the Si concentrations in soil solutions were also elevated to beneficial levels for rice growth. The rice seedlings accumulated more As and its growth was inhibited by Si application in As contaminated/spiked soils. The results indicate that there is an initial aggravation in As toxicity before the beneficial effects of Si fertilizing to rice were revealed when Si application based on fertilizer recommendation rate to As-contaminated paddy soils. Therefore, for As-contaminated paddy soils with high levels of As, the application of Si fertilizer could result in increasing As phytotoxicity and uptake by rice.",
Arsenic,2347597,"Risk assessment of total and bioavailable potentially toxic elements (PTEs) in urban soils of Baghdad-Iraq Abstract: The solubility of soil-associated potentially toxic elements (PTEs) in surrogate biological fluids provides valuable information about their potential health hazard. This work addresses the concentrations and bioaccessibility of nine PTEs (As, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn) in thirty eight agricultural land and playground soils collected from a semi-arid urban area of Baghdad-Iraq. Two surrogate biological fluids (SBFs), macrophage vacuole (MS) and gastric (GS) solutions, were used to extract the metals to simulate the biological availability of the PTEs via inhalation and ingestion exposure routes. ICP/AES was used to quantify PTEs in both strong acid digests (for total concentration), and in the SBF extracts. Soil contamination factors showed that some sites exhibited elevated levels of As (36±10mg/kg), however, these levels of As are not likely to have significant human health impacts whether the particulate arsenic is ingested or/and inhaled. Soil-geochemical variables (including: pH, EC, CO3(=), soil organic carbon (SOC)) and major elements (e.g. Al, Ca, and Fe) were used to interpret the lability of PTEs in the soils. Hazardous index (HI) based non-cancer risk of inhalation and ingestion of PTEs was estimated to be 2-fold higher for that based on total element concentrations compared with that for bioavailable fractions for both children and adults. A similar conclusion was reached for the estimated cancer risk (which was lower than the threshold level of concern for children and adults). A sensitivity analysis showed that there is a 97% chance for children and 90% for adults to have hazardous indices of the total PTEs &gt;1 (the acceptable value); the corresponding metrics for the bioavailable fraction of the elements were 39% for children, and 3% for adults; these results were sensitive to the concentrations of &quot;airborne&quot; soil particles.",
Arsenic,1519041,"Methylated arsenic species in rice: geographical variation, origin and uptake mechanisms Abstract: Rice is a major source of inorganic arsenic (iAs) in the human's diet because paddy rice is efficient at accumulating As. Rice As speciation is dominated by iAs and dimethylarsinic acid (DMA). Here we review the global pattern in rice As speciation and the factors causing the variation. Rice produced in Asia shows a strong linear relationship between iAs and total As concentration with a slope of 0.78. Rice produced in Europe and the US shows a more variable, but generally hyperbolic relationship with DMA being predominant in US rice. Although there is significant genotypic variation in grain As speciation, the regional variations are primarily attributed to environmental factors. Emerging evidence also indicates that methylated As species in rice are derived from the soil, whilst rice plants lack the As methylation ability. Soil flooding and additions of organic matter increase microbial methylation of As, although the microbial community responsible for methylation is poorly understood. Compared with iAs, methylated As species are taken up by rice roots less efficiently but are transported to the grain much more efficiently, which may be an important factor responsible for the spikelet sterility disorder (straight-head disease) in rice. DMA is a weak carcinogen, but the level of ingestion from rice consumption is much lower than that of concern. Questions that require further investigations are identified.",
Arsenic,1677545,"Historical arsenic contamination of soil due to long-term phosphate fertiliser applications Abstract: Archived samples from the Park Grass Experiment, established in 1856, were analysed to determine the impacts of long-term phosphate fertiliser applications on arsenic concentrations in soil and herbage. In plots receiving 35 kg P ha(-1) annually (+P), topsoil As concentrations almost doubled from an initial value of ?10 mg kg(-1) during 1888-1947 and remained stable thereafter. The phosphate fertilisers used before 1948 contained 401-1575 mg As kg(-1), compared to 1.6-20.3 mg As kg(-1) in the later samples. Herbage samples from the +P plots collected during 1888-1947 contained significantly more As than those from the -P plots, but later samples did not differ significantly. Mass-balance calculations show that the increase in soil As can be explained by the As input from P fertiliser applications before 1948. The results demonstrate that the P fertilisers used on the Park Grass Experiment before 1948 caused substantial As contamination of the soil.",
Arsenic,710807,"Arsenic- and cadmium-induced toxicogenomic response in mouse embryos undergoing neurulation Abstract: Arsenic (As) and cadmium (Cd) are well-characterized teratogens in animal models inducing embryotoxicity and neural tube defects (NTDs) when exposed during neurulation. Toxicological research is needed to resolve the specific biological processes and associated molecular pathways underlying metal-induced toxicity during this timeframe in gestational development. In this study, we investigated the dose-dependent effects of As and Cd on gene expression in C57BL/6J mouse embryos exposed in utero during neurulation (GD8) to identify significantly altered genes and corresponding biological processes associated with embryotoxicity. We quantitatively examined the toxicogenomic dose-response relationship at the gene level. Our results suggest that As and Cd induce dose-dependent gene expression alterations representing shared (cell cycle, response to UV, glutathione metabolism, RNA processing) and unique (alcohol/sugar metabolism) biological processes, which serve as robust indicators of metal-induced developmental toxicity and indicate underlying embryotoxic effects. Our observations also correlate well with previously identified impacts of As and Cd on specific genes associated with metal-induced toxicity (Cdkn1a, Mt1). In summary, we have identified in a quantitative manner As and Cd induced dose-dependent effects on gene expression in mouse embryos during a peak window of sensitivity to embryotoxicity and NTDs in the sensitive C57BL/6J strain.",
Arsenic,1508592,"Synthesis and application of an environmentally insensitive Cy3-based arsenical fluorescent probe to identify adaptive microbial responses involving proximal dithiol oxidation Abstract: Reversible disulfide oxidation between proximal cysteines in proteins represents a common regulatory control mechanism to modulate flux through metabolic pathways in response to changing environmental conditions. To enable in vivo measurements of cellular redox changes linked to disulfide bond formation, we have synthesized a cell-permeable thiol-reactive affinity probe (TRAP) consisting of a monosubstituted cyanine dye derivatized with arsenic (i.e., TRAP_Cy3) to trap and visualize dithiols in cytosolic proteins. Alkylation of reactive thiols prior to displacement of the bound TRAP_Cy3 by ethanedithiol permits facile protein capture and mass spectrometric identification of proximal reduced dithiols to the exclusion of individual cysteines. Applying TRAP_Cy3 to evaluate cellular responses to increases in oxygen and light levels in the photosynthetic microbe Synechococcus sp. PCC7002, we observe large decreases in the abundance of reduced dithiols in cellular proteins, which suggest redox-dependent mechanisms involving the oxidation of proximal disulfides. Under these same growth conditions that result in the oxidation of proximal thiols, there is a reduction in the abundance of post-translational oxidative protein modifications involving methionine sulfoxide and nitrotyrosine. These results suggest that the redox status of proximal cysteines responds to environmental conditions, acting to regulate metabolic flux and minimize the formation of reactive oxygen species to decrease oxidative protein damage.",
Arsenic,2088504,"Risk assessment of an abandoned pyrite mine in Spain based on direct toxicity assays Abstract: This research reports the risk assessment of an abandoned pyrite mine using direct toxicity assays of soil and groundwater samples taken at the site. The toxicity of As and heavy metals from mining soils to soil and aquatic organisms was studied using the Multispecies Soil System (MS-3) in soil columns. Ecotoxicological assessment was performed with soil samples diluted with a control soil at concentrations of 12.5, 25, 50 and 100% test soil/soil (w/w). In this way, changes in the mobility and bioavailability of soil contaminants due to changes in geochemical soil properties via soil dilution were studied. The toxicity of water samples was tested on algae and Daphnia magna. The assessment of the mining area indicated that the current presence of As and heavy metals at the site may cause injuries to soil and aquatic organisms in the entire research area. Moreover, this investigation demonstrated that changes in geochemical conditions can increase the availability of arsenic and, consequently, the environmental risk of these soils. A good correlation was not found between toxicity parameters and the concentrations of soil contaminants based on total and extracted element concentrations. This finding reinforces the usefulness of direct toxicity assays for evaluating environmental risk.",
Arsenic,1356894,"Identification of gene expression in the urothelium of rats fed dimethylarsinic acid using microarray analysis Abstract: Dimethylarsinic acid (DMA), a major organic metabolite of arsenic in most mammals including humans, has been shown to be a bladder carcinogen in rats when administered in the diet or in the drinking water. However, the molecular mechanisms underlying DMA bladder carcinogenesis remain unclear. The purpose of the present study is to identify the DMA-responsive genes in the urinary bladder epithelial cells of rats. Female F344 rats were fed 100 ppm DMA or control diet. Five rats from each group were sacrificed 24 hours and 2 weeks after the start of treatment and RNA was isolated from urinary bladder epithelial cells using the Qiagen method. RNA of DMA-treated and control rats was labeled with Cy3 and Cy5 fluorescent tags respectively and simultaneously hybridized to a Rat 10K chip (MWG Biotech) containing 10, 000 genes. Genes in which the expression ratio of paired DMA-treated to control tissue showed a greater than 2-fold difference and was observed in at least 4 rats were considered to be DMA-responsive genes. Seventeen genes were down-regulated after 24 hours of DMA treatment and no up-regulated genes were observed. After 2 weeks of DMA treatment, an expected increase in the number of DMA-responsive genes was found (32 genes). Seven of these genes were up-regulated by DMA, while 25 genes were down-regulated by DMA. Furthermore, the expression of 12 genes was suppressed both after 24 hours and 2 weeks. These findings suggest that analysis of expression profiles may provide clues for elucidation of DMA-induced bladder carcinogenesis. Further investigation of gene expression after long-term DMA administration is underway.",
Arsenic,131326,"An integrated pharmacokinetic and pharmacodynamic study of arsenite action: 2 Heme oxygenase induction in mice Abstract: Heme oxygenase (HO) is the rate-limiting enzyme in heme degradation and its activity has a significant impact on intracellular heme pools. Rat studies indicate that HO induction is a sensitive, dose-dependent response to arsenite (As(III)) exposure in both liver and kidney. The objective of this study was to evaluate the relationship of HO induction to administered As(III) dose, and concentrations of inorganic arsenic (iAs) in tissues and urine. Levels of iAs, mono- (MMA) and dimethylated arsenic (DMA) as well as HO activity were determined in liver, lung and kidney over time in female B6C3F1 mice given a single oral dose of 0, 1, 10, 30 or 100 ?mol/kg As(III). Increased HO activity was a time and dose-dependent response in liver and kidney, but not in lung. Activity peaked in the 4–6 h time range in liver and kidney with the responsiveness in liver being 2- to 3-fold greater than kidney. The lowest observed effect levels (LOELs) in this study for HO induction are 30 and 100 ?mol/kg, respectively, in liver and kidney. The predominant form of arsenic (As) was iAs in liver at all doses, whereas DMA was the predominant form of As in kidney at all doses. Three- to four-fold higher levels of iAs were achieved in liver compared to kidney. MMA was the least abundant form of As in liver and kidney, never exceeding more than 20% of the total As present. The concentration of iAs in tissue or urine demonstrated the strongest correlation with HO activity in both liver and kidney. Results of this study suggest that HO induction is a biomarker of effect that is specific for tissue iAs because a high, but nontoxic, acute dose of DMA (5220 ?mol/kg) did not induce HO in mice. Thus, HO induction has potential for use as a biomarker of effect for inorganic arsenic exposure and may be used as an indicator response to further the development of a biologically-based dose response model for As.",
Arsenic,710923,"Fetal arsenic exposure appears to facilitate endocrine disruption by postnatal diethylstilbestrol in neonatal mouse adrenal Abstract: Fetal exposure of mice to arsenic and subsequent postnatal diethylstilbestrol (DES) facilitates production of urogenital system and liver tumors in the offspring when they reach adulthood. The adrenal is a target of endocrine disruption that could influence tumor formation at other sites. Thus, we examined possible fetal arsenic-induced adrenal effects as a potential basis of arsenic enhancement of DES carcinogenesis. Pregnant CD1 mice were given drinking water containing 85 ppm arsenic as sodium arsenite or unaltered water from day 8 to day 18 of gestation and were allowed to deliver normally. Groups of offspring were subsequently injected s.c. on postpartum days 1-5 with DES (2 microg/pup/day) and killed on postnatal day 12. Total RNA was isolated from the whole adrenal glands, and the expression of various genes was analyzed by real-time RT-PCR. Fetal arsenic exposure greatly enhanced DES-induced, estrogen-linked gene expression, such as estrogen receptor-alpha and trefoil factors. Expression of genes involved with steroid metabolism and/or methionine metabolism was also increased, including genes encoding for 17beta-hydroxysteroid dehydrogenase type 5 (HSD17beta5) and androstenedione 15alpha-hydroxylase (Cyp2a4). The transcripts for homocysteine cycling genes (betaine-homocysteine methyltransferase and thioether S-methyltransferase) and developmental marker genes (alpha-fetoprotein, insulin-like growth factor 2 and IGF binding protein-1), were also higher with arsenic plus DES than either treatment alone. Thus, exposure of the mouse to arsenic during a critical period of fetal development may potentially alter adrenal genetic programming, leading to endocrine disruption and potentially enhancing tumor formation together with DES at other sites much later in life. Functional studies, such as changes in circulating steroids, would greatly support this hypothesis, and are planned.",
Arsenic,628718,"Inorganic arsenic compounds and methylated metabolites induce morphological transformation in two-stage BALB/c 3T3 cell assay and inhibit metabolic cooperation in V79 cell assay Abstract: We have performed two-stage transformation assay using BALB/c 3T3 cells to determine initiating and promoting activities of disodium arsenate, sodium arsenite, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). Treatment with these arsenic compounds at the initiating stage induced significant numbers of transformed foci when cells were post-treated with 12-O-tetradecanoylphorbol-13-acetate (TPA). Disodium arsenate was active at the concentrations of 15–30 µM, sodium arsenite 5–20 µM, and DMAA 1–2 mM. MMAA required 10 mM to induce cell transformation. The concentrations of these compounds (except DMAA) that induced transformation were highly growth-inhibitory (more than 50%). DMAA induced transformation foci at growth inhibition levels of 66 to 84%. In experiments on promoting activity, cells pretreated with a sub-threshold dose of 20-methylcholanthrene (MCA, 0.2 µg/ml) or sodium arsenite (10 µM) were used. Transformation was enhanced by post-treatment with disodium arsenate (1–10 µM), sodium arsenite (0.5–2 µM), and MMAA (200–1000 µM), but not with DMAA. Studies of gap junctional intercellular communication using the V79 cell metabolic cooperation assay showed that the arsenic compounds (except DMAA) exhibited inhibitory activity. Thus, most arsenicals were shown to have not only initiating activity, but also promoting activity. In addition, inorganic arsenicals, especially trivalent sodium arsenite, were more active than organic ones and exhibited promoting activity at one-order of magnitude lower than initiating activity. These results suggest that from the viewpoint of human hazard, more attention should be paid to the tumor promoting activity of inorganic arsenic compounds.",
Arsenic,1025183,"High dietary fat exacerbates arsenic-induced liver fibrosis in mice Abstract: Many factors could potentially affect the process of arsenic-induced liver fibrosis. The present study was undertaken to examine the effect of high fat diet on arsenic-induced liver fibrosis and preneoplastic changes. Mice were given sodium arsenite (As3+, 200 ppm) or sodium arsenate (As5+, 200 ppm) in the drinking water for 10 months, and provided a normal diet or a diet containing 20% added fat. Serum aspartate aminotransferase (AST), indicative of liver injury, was elevated in both arsenite and arsenate groups, and a high fat diet further increased these levels. Histopathology (H&amp;E and Masson stain) showed that liver inflammation, steatosis (fatty liver), hepatocyte degeneration, and fibrosis occurred with arsenic alone, but their severity was markedly increased with the high fat diet. Total liver RNA was isolated for real-time RT-PCR analysis. Arsenic exposure increased the expression of inflammation genes, such as TNF-alpha, IL-6, iNOS, chemokines, and macrophage inflammatory protein-2. The expression of the stress-related gene heme oxygenase-1 was increased, while metallothionein-1 and GSH S-transferase-pi were decreased when arsenic was combined with the high fat diet. Expression of genes related to liver fibrosis, such as procollagen-1 and -3, SM-actin and TGF-beta, were synergistically increased in the arsenic plus high fat diet group. The expression of genes encoding matrix metalloproteinases (MMP2, MMP9) and tissue inhibitors of metalloproteinases (TIMP1, TIMP2) was also enhanced, suggestive of early oncogenic events. In general, arsenite produced more pronounced effects than arsenate. In summary, chronic inorganic arsenic exposure in mice produces liver injury, and a high fat diet markedly increases arsenic-induced hepatofibrogenesis.",
Arsenic,1345994,Exposure to arsenic in air and drinking water: Results of a case-control study in northern Chile Abstract: ,
Arsenic,710877,"Attenuation of arsenic neurotoxicity by curcumin in rats Abstract: In view of continued exposure to arsenic and associated human health risk including neurotoxicity, neuroprotective efficacy of curcumin, a polyphenolic antioxidant, has been investigated in rats. A significant decrease in locomotor activity, grip strength (26%) and rota-rod performance (82%) was observed in rats treated with arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) as compared to controls. The arsenic treated rats also exhibited a decrease in the binding of striatal dopamine receptors (32%) and tyrosine hydroxylase (TH) immunoreactivity (19%) in striatum. Increased arsenic levels in corpus striatum (6.5 fold), frontal cortex (6.3 fold) and hippocampus (7.0 fold) associated with enhanced oxidative stress in these brain regions, as evident by an increase in lipid perioxidation, protein carbonyl and a decrease in the levels of glutathione and activity of superoxide dismutase, catalase and glutathione peroxidase with differential effects were observed in arsenic treated rats compared to controls. Simultaneous treatment with arsenic (sodium arsenite, 20 mg/kg body weight, p.o., 28 days) and curcumin (100 mg/kg body weight, p.o., 28 days) caused an increase in locomotor activity and grip strength and improved the rota-rod performance in comparison to arsenic treated rats. Binding of striatal dopamine receptors and TH expression increased while arsenic levels and oxidative stress decreased in these brain regions in co-treated rats as compared to those treated with arsenic alone. No significant effect on any of these parameters was observed in rats treated with curcumin (100 mg/kg body weight, p.o., 28 days) alone compared to controls. A significant protection in behavioral, neurochemical and immunohistochemical parameters in rats simultaneously treated with arsenic and curcumin suggest the neuroprotective efficacy of curcumin.",
Arsenic,1519159,Elucidating Mechanisms of Competitive Sorption at the Mineral/Water Interface Abstract: ,
Arsenic,1327578,"Altered protein synthesis in rat kidney cells exposed to semiconductor materials Abstract: It is thought that the extensive industrial use of arsenic, gallium and indium, which have applications as the materials for III–V semiconductors, will increase human exposure to these compounds in the near future. We have undertaken the development of new biological indicators for assessing exposure to these elements. Element-specific alterations in protein synthesis patterns were expected to occur following exposure to arsenic compounds. We examined alterations in protein synthesis in primary cultures of rat kidney proximal tubule epithelial cells by sodium arsenite, gallium chloride and indium chloride, utilizing two-dimensional gel electrophoresis. After incubation with the chemicals for 20 h, newly synthesized proteins were labeled with [35S]methionine. A protein with a molecular weight (Mr) of 30 000 was markedly induced on exposure to 10 ?m arsenite or 300 ?m gallium chloride, and synthesis of proteins with Mr values of 85 000, 71 000, 65 000, 51 000, 38 000 and 28 000 were also increased by exposure to arsenite and gallium chloride. No significant changes were observed upon exposure to indium. Some of these increased proteins could be heat-shock proteins.",
Arsenic,2337097,"The importance of shallow hydrothermal island arc systems in ocean biogeochemistry Abstract: Hydrothermal venting often occurs at submarine volcanic calderas on island arc chains, typically at shallower depths than mid-ocean ridges. The effect of these systems on ocean biogeochemistry has been under-investigated to date. Here we show that hydrothermal effluent from an island arc caldera was rich in Fe(III) colloids (0.02-0.2 mu m; 46% of total Fe), contributing to a fraction of hydrothermal Fe that was stable in ocean water. Iron(III) colloids from island arc calderas may be transferred into surrounding waters (generally 0-1500m depth) by ocean currents, thereby potentially stimulating surface ocean primary productivity. Hydrothermal Fe oxyhydroxide particles (&gt;0.2 mu m) were also pervasive in the studied caldera and contained high concentrations of oxyanions of phosphorus (P), vanadium (V), arsenic (As), and manganese (Mn). Hydrothermal island arcs may be responsible for&gt;50% of global hydrothermal P scavenging and&gt;40% V scavenging, despite representing &lt;10% of global hydrothermal fluid flow. <br> <br>Key Points <br> <br>&lt;list list-type=""bulleted"" id=""grl51349-list-0001""&gt; &lt;list-item id=""grl51349-li-0001""&gt;A large portion of iron from hydrothermal island arc calderas exists as colloids &lt;list-item id=""grl51349-li-0002""&gt;These colloids coprecipitate important amounts of dissolved oxyanions &lt;list-item id=""grl51349-li-0003""&gt;Iron colloids from hydrothermal island arcs may stimulate primary productivity",
Arsenic,1025887,"Toxicological effects and bioaccumulation in the freshwater clam (Corbicula fluminea) following exposure to trivalent arsenic Abstract: Contamination of aquatic environments by arsenic is a serious worldwide problem. The main objective of this work was to evaluate the response of a freshwater clam (Corbicula fluminea) to arsenic (As III) exposure and infer its potential as a biological indicator of contamination. Metallothioneins (MTs) were used as indicators of metalloid toxicity in combination with an histological and histochemical evaluation. After a period of acclimatization in the laboratory, 50 C. fluminea (0.4 g +/- 0.1) were exposed to different nominal concentrations of arsenic (100, 300, 500, and 1000 microg L(-1)) for 7 days. The concentration of total As III in the water and in the tissues of the organisms was determined by atomic absorption spectrometry, and MTs were quantified through differential pulse polarography. Results suggest that the organisms exposed to the concentrations of 300 and 1000 microg As L(-1) accumulated the highest levels of As III in the tissues (17 +/- 9 and 15 +/- 3 microg g(-1) distilled water, respectively), which was confirmed through histochemical analysis. An apparent induction of MTs was also observed in the organisms exposed to As III, suggesting that C. fluminea possesses some capacity for arsenic regulation. The results suggest that the induction of MTs may be of high interest as a biomarker for arsenic contamination in aquatic environments, and confirms the potential of C. fluminea as a biological indicator.",
Arsenic,1020059,"Arsenic speciation in the urine and hair of individuals exposed to airborne arsenic through coal-burning in Guizhou, PR China Abstract: The extent of exposure of residents of Changqing (Guizhou, PR China) to arsenic through coal-burning was investigated. Despite the low coal-arsenic content (56.3+/-42.5 mg As kg(-1)) when compared with coals collected at different location and times from the same province, more than 30% of the study subjects have shown symptoms of arsenicosis. Coal, urine, hair, and water samples were collected in mid-September 2001 and analysed for arsenic. The average urinary and hair-arsenic concentrations in the exposed subjects were 71.4+/-37.1 microg As g(-1) creatinine (control 41.6+/-12.1) and 7.99+/-8.16 mg kg(-1), respectively. A positive correlation between the hair and urinary-arsenic concentration (R(2)=0.601) was found. There was no significant difference between females and males for both urinary and hair-arsenic concentrations. Females were found to have a higher dimethylarsinic acid but lower percentages of inorganic arsenic and monomethylarsonic acid in their urine than males.",
Arsenic,1597326,"Environmental survey in the Tuul and Orkhon River basins of north-central Mongolia, 2010: Metals and other elements in streambed sediment and floodplain soil Abstract: Streambed sediment and subsurface floodplain soil were sampled for elemental analyses from 15 locations in river basins of north-central Mongolia during August 2010. Our primary objective was to conduct a reconnaissance-level assessment of potential inputs of toxicologically important metals and metalloids to Lake Baikal, Russia, that might originate from mining and urban activities within tributaries of the Selenga River in Mongolia. Samples were collected in triplicate from all sites, then dried, and sieved to <2 mm for analysis by portable X-ray florescence spectroscopy and by inductively coupled plasma mass spectrometry after digestion with concentrated nitric and hydrochloric acids. Arsenic, copper, and mercury were greatly elevated in sediment and floodplain soil collected from tributary streams located near two major mining operations. Lead and zinc were moderately elevated in streambed sediment and in floodplain soil obtained from a small tributary in the capital city of Ulaanbaatar, but those concentrations were considerably less than probable effects benchmarks. Historical and possibly present mining activities have led to considerable metal contamination in certain tributaries of the Orkhon River in north-central Mongolia; however, metals originating from those sources did not appear to be accumulating in sediments at our downstream-most sampling sites located near the border between Mongolia and Russia.",
Arsenic,112477,"Identification of interspecies concordance of mechanisms of arsenic-induced bladder cancer Abstract: Exposure to arsenic causes cancer by inducing a variety of responses that affect the expression of genes associated with numerous biological pathways leading to altered cell growth and proliferation, signaling, apoptosis and oxidative stress response. Affymetrix GeneChip arrays were used to detect gene expression changes following dimethylarsinic acid (DMA) exposure to human bladder cells (UROtsa) or rat bladder cells (MYP3) and rat bladder epithelium in vivo at comparable doses. Using different experimental models coupled with transcriptional profiling allowed investigation of the correlation of mechanisms of DMA-induced toxicity between in vitro and in vivo treatment and across species. Our observations suggest that DMA-induced gene expression in UROtsa cells is distinct from that observed in the MYP3 cells. Principal component analysis shows a more distinct separation by treatment and dose in MYP3 cells as compared to UROtsa cells. However, at the level of pathways and biological networks, DMA affects both common and unique processes in the bladder transitional cells of human and rats. Twelve pathways were found common between human in vitro, rat in vitro and rat in vivo systems. These included signaling pathways involved in adhesion, cellular growth and differentiation. Fifty-five genes found to be commonly expressed between rat in vivo and rat in vitro systems were involved in diverse functions such as cell cycle regulation, lipid metabolism and protein degradation. Many of the genes, processes and pathways have previously been associated with arsenic-induced toxicity. Our finding reiterates and also identifies new biological processes that might provide more information regarding the mechanisms of DMA-induced toxicity. The results of our analysis further suggest that gene expression profiles can address pertinent issues of relevance to risk assessment, namely interspecies extrapolation of mechanistic information as well as comparison of in vitro to in vivo response.",
Arsenic,1797845,"The safety and efficacy of gastric fundal variceal obliteration using N-butyl-2-cyanoacrylate; The experience of a single Canadian tertiary care centre Abstract: Background/Aim: Bleeding from Gastric Varices (GV) is not only life threatening, but also leads to many hospitalizations, contributes to morbidity and is resource intensive. GV are difficult to diagnose and their treatment can be challenging due to their location and complex structure. To assess the safety and efficacy of endoscopic gastric fundal variceal gluing using periodic endoscopic injections of N-butyl-2-cyanoacylate (NBCA) and to assess the utility of endoscopic ultrasound (EUS) in assessing for the eradication of GV post-NBCA treatment. Materials and Methods: Analysis of prospectively collected data of a cohort of patients with GV who underwent periodic endoscopic variceal gluing from 2005 to 2011. Outcomes included success of GV obliteration, incidence of rebleeding, complications from the procedure, and analysis of factors that might predict GV rebleeding. The success of GV eradication was assessed by both EUS and direct endoscopy. Results: The cohort consisted of 29 consecutive patients that had undergone NBCA injection for GV. The mean age was 60.8 years standard deviations (SD 13.3, range 20-81). The average follow-up was 28 months (SD 19.61, range 1-64) and the most common cause for GV was alcoholic liver cirrhosis (34.48%). A total of 91 sessions of NBCA injections were carried out for 29 patients (average of 3.14 sessions/patient, SD 1.79, range 1-8) with a total of 124 injections applied (average of 4.28 injections/patient, SD 3.09, range 1-13). 24 patients were treated for previously documented GV bleeding while five were treated for primary prevention. Overall, 79% of patients were free of rebleeding once three sessions of histoacryl ® injection were completed. None of the patients treated for primary prevention developed bleeding during follow-up. 11 of the 24 patients (46%) with previous bleeding however had rebleeding. 4/11 (36%) patients had GV rebleeding while awaiting scheduled additional NBCA sessions. 19/29 (60%) patients had complete eradication of GV, 11/19 (58%) documented by endoscopic assessment alone, 4/19 (21%) by EUS alone and 4/19 (21%) by both techniques. Two of the 11 (18%) patients that had rebleeding had recurrence of GV bleeding after documented eradication by EUS compared to 5/11 (45%) patients documented eradication by endoscopic assessment and 2/11 (18%) patients that had rebleeding after documented eradication by both modalities. Twenty five patients in total had documented residual GV by EUS (14, 56%), direct endoscopic assessment (18, 72%) or both modalities (9, 36%), two of which developed recurrent bleeding (13%). No immediate or long-term complications of NBCA injection occurred, nor any related endoscopic complications were reported in any of these cases during the time of follow-up. Conclusion: NBCA injection of GV is a safe and successful therapeutic intervention. A minimum of three endoscopic sessions is required to significantly decrease the risk of bleeding/rebleeding. In this small sample of patients, neither EUS nor direct endoscopic assessment was reliable in predicting the recurrence of GV bleeding.",
Arsenic,1021845,"Heavy metals and arsenic concentrations in ten fish species from the Šalek lakes (Slovenia): assessment of potential human health risk due to fish consumption Abstract: The study, which measured the concentrations of Hg, Pb, Cd, Zn and As in various fish tissues (muscle, gill and liver) of 10 fish species (Abramis brama danubii, Alburnus alburnus alburnus, Barbus meridionalis petenyi, Carassius auratius gibelio, Cyprinus carpio, Lepomis gibossus, Leuciscius cephalus cephalus, Perca fluviatilis fluviatilis, Rutilus rutilus, Scardinus erythrophtlalmus erythrophtlalmus) collected in the Šalek lakes, is the first survey regarding metal concentrations in fish species with samples originating from Slovene lakes, while only a limited number of such studies have been carried out in southeastern Europe. Since these lakes are situated in the close vicinity of the largest Slovene thermal power plant, the study provides an insight into the potential impact of increased levels of metals in the environment as well as an estimate of the contamination of fish tissues with metals. Furthermore, it was possible to compare the results obtained with those from other studies regarding metal levels in freshwater fish species. The mean metal concentrations of different tissues irrespective of species varied in the following ranges: Zn 4.31-199 mg/kg ww, Pb 0.01-0.48 mg/kg ww, As 0.02-0.44 mg/kg ww, Hg <0.01-0.31 mg/kg ww, Cd < 0.01-0.19 mg/kg ww. In general, higher contents of Hg were found in muscles and livers than in gills and higher contents of As in gills and livers than in muscles, respectively. The accumulation of Pb and Zn was most pronounced in gills. The result obtained regarding metal concentrations in fish revealed that the ecosystems of the Šalek lakes are not polluted with Hg and Pb, slightly loaded with As and Cd and moderately polluted with Zn. In addition, the potential human health risk due to fish consumption was assessed. This showed that the estimated weekly intakes for all metals were far below provisional permissible tolerable weekly intakes determined by WHO/FAO. The consumption of fish from the Šalek lakes, therefore, does not pose a risk to human health.",
Arsenic,1936133,"Effect of arsenic contamination on bacterial and fungal biomass and enzyme activities in tropical arsenic-contaminated soils Abstract: The importance of assessing the impacts of soil arsenic (As) contamination on microbial properties lay on the fact that microbes are instrumental in nutrient cycling and are therefore indicators of soil quality. In this study, soil chemical extraction methods were used to extract labile and freely exchangeable As (water-soluble As and sodium bicarbonate-extractable As), amorphous/crystalline Fe and Mn oxide-bound As (acid ammonium oxalate-extractable As and hydroxylamine hydrochloride-extractable As), and their impacts on microbial biomass (microbial biomass C, total bacterial and fungal biomass, active bacterial and fungal biomass), enzyme activities representing four major soil biogeochemical cycles, i.e., C (?-glucosidase activity), N (urease activity), P (acid phosphomonoesterase activity), S (acryl-sulfatase activity), and microbial activity (fluorescein diacetate hydrolysis and dehydrogenase activity) were investigated in As-contaminated soils of Ambagarh Chauki block, Chhattisgarh, Central India. The results revealed that the majority of the As in soils resided in the Fe/Mn oxide-bound fraction. The microbial biomass C, total and active fungal biomass, and enzyme activities were significantly inhibited by all the forms of As. However, water-soluble As, even though occupying only a small portion of the total As (0.9–2.9 %), exerted the greatest impact. Interestingly, total and active bacterial biomass was not significantly affected by As toxicity, suggesting their resistance to As. Urease activity was not affected by As pollution.",
Arsenic,2298733,"Cationic chains of phosphanyl- and arsanylboranes Abstract: Whilst catena-phosphorus cations have been intensively studied in the last years, mixed Group?13/15 element cationic chains have not yet been reported. Reaction of the pnictogenboranes H2 EBH2 ?NMe3 (E=P, As) with monohalideboranes lead to the cationic chain compounds [Me3 N?BH2 EH2 BH2 ?NMe3 ][X] (E=P, As; X=AlCl4 , I) and [Me3 N?BH2 PH2 BH2 PH2 BH2 ?NMe3 ][X] (X=I, VCl4 (thf)2 ), respectively. All of the compounds have been characterized by X-ray structure analysis, NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations elucidate the reaction pathway, the high thermodynamic stability, the charge distribution within the chain and confirm the observed solid-state structures.",
Arsenic,783313,"Arsenic and manganese exposure and children's intellectual function Abstract: Recently, epidemiologic studies of developmental neurotoxicology have been challenged to increase focus on co-exposure to multiple toxicants. Earlier reports, including our own work in Bangladesh, have demonstrated independent associations between neurobehavioral function and exposure to both arsenic (As) and manganese (Mn) in school-aged children. Our earlier studies, however, were not designed to examine possible interactive effects of exposure to both As and Mn. To allow investigation of possible synergistic impact of simultaneous exposures, we recruited a new sample of 299 8-11 year old children, stratified by design on As (above and below 10 ?g/L) and Mn (above and below 500 ?g/L) concentrations of household wells. When adjusted only for each other, both As and Mn in whole blood (BAs; BMn) were significantly negatively related to most WISC-IV subscale scores. With further adjustment for socio-demographic features and ferritin, BMn remained significantly associated with reduced Perceptual Reasoning and Working Memory scores; associations for BAs, and for other subscales, were expectably negative, significantly for Verbal Comprehension. Urinary As (per gram creatinine) was significantly negatively associated with Verbal Comprehension scores, even with adjustment for BMn and other contributors. Mn by As interactions were not significant in adjusted or unadjusted models (all p's>0.25). Findings are consistent with other reports documenting adverse impact of both As and Mn exposure on child developmental outcomes, although associations appear muted at these relatively low exposure levels.",
Arsenic,2149112,"Arsenic species formed from arsenopyrite weathering along a contamination gradient in circumneutral river floodplain soils Abstract: Arsenic is a toxic trace element, which commonly occurs as contaminant in riverine flood-plains and associated wetlands affected by mining and ore processing. In this study, we investigated the solid-phase speciation of As in river floodplain soils characterized by circumneutral pH (5.7-7.1) and As concentrations of up to 40.3 g/kg caused by former mining of arsenopyrite-rich ores. Soil samples collected in the floodplain of Ogosta River (Bulgaria) were size-fractionated and subsequently analyzed using a combination of X-ray fluorescence (XRF) spectrometry, powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and selective chemical extraction of poorly-crystalline mineral phases. Arsenic and Fe were found to be spatially correlated and both elements were strongly enriched in the fine soil particle size fractions (&lt;2 ?m and 2-50 ?m). Between 14 and 82% of the total As was citrate-ascorbate extractable. Molar As/Fe ratios were as high as 0.34 in the bulk soil extracts, and increased up to 0.48 in extracts of the fine particle size fractions. Arsenic K-edge XAS spec-tra showed the predominance of As(V), and were well fitted with a reference spectrum of As(V) adsorbed to ferrihydrite. Whereas no As(III) was detected, considerable amounts of As(-I) were present and identified as arsenopyrite originating from the mining waste. Iron K-edge XAS revealed that in addition to As(V) adsorbed to ferrihydrite, X-ray amorphous As(V)-rich hydrous ferric oxides ('As-HFO') with a reduced number of corner-sharing FeO6 octahedra relative to ferrihydrite were the dominating secondary As species in the soils. The extremely high concentrations of As in the fine particle size fractions (up to 214 g/kg) and its association with poorly crystalline Fe(III) oxyhydroxides and As-HFO phases suggest a high As mobilization potential under both oxic and anoxic conditions, as well as a high bioaccessibility of As upon ingestion, dermal contact, or inhalation by humans or animals.",
Arsenic,2088323,Manganese and iron oxide immobilized activated carbons precursor to dead biomasses in the remediation of cadmium-contaminated waters Abstract: ,
Arsenic,1579327,"A molecular dynamics study of the structural and dynamical properties of putative arsenic substituted lipid bilayers Abstract: Cell membranes are composed mainly of phospholipids which are in turn, composed of five major chemical elements: carbon, hydrogen, nitrogen, oxygen, and phosphorus. Recent studies have suggested the possibility of sustaining life if the phosphorus is substituted by arsenic. Although this issue is still controversial, it is of interest to investigate the properties of arsenated-lipid bilayers to evaluate this possibility. In this study, we simulated arsenated-lipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-arsenocholine (POAC), lipid bilayers using all-atom molecular dynamics to understand basic structural and dynamical properties, in particular, the differences from analogous 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, (POPC) lipid bilayers. Our simulations showed that POAC lipid bilayers have distinct structural and dynamical properties from those of native POPC lipid bilayers. Relative to POPC lipid bilayers, POAC lipid bilayers have a more compact structure with smaller lateral areas and greater order. The compact structure of POAC lipid bilayers is due to the fact that more inter-lipid salt bridges are formed with arsenate-choline compared to the phosphate-choline of POPC lipid bilayers. These inter-lipid salt bridges bind POAC lipids together and also slow down the head group rotation and lateral diffusion of POAC lipids. Thus, it would be anticipated that POAC and POPC lipid bilayers would have different biological implications.",
Arsenic,1337612,"Arbuscular mycorrhizal fungi in arsenic-contaminated areas in Brazil Abstract: Arbuscular mycorrhizal fungi (AMF) are ubiquitous and establish important symbiotic relationships with the majority of the plants, even in soils contaminated with arsenic (As). In order to better understand the ecological relationships of these fungi with excess As in soils and their effects on plants in tropical conditions, occurrence and diversity of AMF were evaluated in areas affected by gold mining activity in Minas Gerais State, Brazil. Soils of four areas with different As concentrations (mgdm(-3)) were sampled: reference Area (10); B1 (subsuperficial layer) (396); barren material (573), and mine waste (1046). Soil sampling was carried out in rainy and dry seasons, including six composite samples per area (n=24). AMF occurred widespread in all areas, being influenced by As concentrations and sampling periods. A total of 23 species were identified, belonging to the following genus: Acaulospora (10 species), Scutellospora (4 species), Racocetra (3 species), Glomus (4 species), Gigaspora (1 species) and Paraglomus (1 species). The most frequent species occurring in all areas were Paraglomus occultum, Acaulospora morrowiae and Glomus clarum. The predominance of these species indicates their high tolerance to excess As. Although arsenic contamination reduced AMF species richness, presence of host plants tended to counterbalance this reduction.",
Arsenic,626964,"Implications of oxidative stress and hepatic cytokine (TNF-alpha and IL-6) response in the pathogenesis of hepatic collagenesis in chronic arsenic toxicity Abstract: Introduction: Noncirrhotic portal fibrosis has been reported to occur in humans due to prolonged intake of arsenic contaminated water. Further, oxystress and hepatic fibrosis have been demonstrated by us in chronic arsenic induced hepatic damage in murine model. Cytokines like tumor necrosis factor ? (TNF-?) and interleukin 6 (IL-6) are suspected to play a role in hepatic collagenesis. The present study has been carried out to find out whether increased oxystress and cytokine response are associated with increased accumulation of collagen in the liver due to prolonged arsenic exposure and these follow a dose–response relationship. Methods: Male BALB/c mice were given orally 200 ?l of water containing arsenic in a dose of 50, 100, and 150 ?g/mouse/day for 6 days a week (experimental group) or arsenic-free water (<0.01 ?g/l, control group) for 3, 6, 9 and 12 months. Hepatic glutathione (GSH), protein sulfhydryl (PSH), glutathione peroxidase (GPx), Catalase, lipid peroxidation (LPx), protein carbonyl (PC), interleukin (IL-6), tumor necrosis factor (TNF-?), arsenic and collagen content in the liver were estimated from sacrificed animals. Results: Significant increase of lipid peroxidation and protein oxidation in the liver associated with depletion of hepatic thiols (GSH, PSH), and antioxidant enzymes (GPx, Catalase) occurred in mice due to prolonged arsenic exposure in a dose-dependent manner. Significant elevation of hepatic collagen occurred at 9 and 12 months in all the groups associated with significant elevation of TNF-? and IL-6. However, arsenic level in the liver increased progressively from 3 months onwards. There was a positive correlation between the hepatic arsenic level and collagen content (r = 0.8007), LPx (r = 0.779) and IL-6 (r = 0.7801). Further, there was a significant negative correlation between GSH and TNF-? (r = ?0.5336)) and LPx (r = ?0.644). Conclusion: Increasing dose and duration of arsenic exposure in mice cause progressive increase of oxystress and elevation of cytokines associated with increasing level of collagen in the liver.",
Arsenic,1345086,"Effect of vitamin E supplementation on hematological and plasma biochemical parameters during long term exposure of arsenic in goats Abstract: The present investigation was designed to determine whether supplementation of different level of vitamin E for 12 months to arsenic exposed goats (50 ppm as sodium arsenite) affords protection against the blood hemato-biochemical parameters caused by the metalloid. A total of 24 crossbred (Alpine×Beetal) lactating goats were assigned randomly into 4 equal groups (control, T1, T2 and T3) of 6 in each, on the basis of average body weight (36.10±0.11 kg) and milk yield (1.61±0.04 kg/d). The animals in T1, T2 and T3 were given 50 ppm arsenic, while in T2 and T3, additionally; vitamin E at the rate of 100 IU and 150 IU/kg dry matter (DM) respectively was additionally supplemented for the period of 12 months. Hemoglobin (Hb), total leukocyte (TLC) and blood lymphocyte % were decreased (p<0.05) in arsenic fed groups and vitamin E supplementation in the experimental group showed a protective potential. Significant increases (p<0.05) in aspertate transaminase (AST) and alanine transaminase (ALT) activities among arsenic supplemented groups were recorded, however vitamin E supplementation at higher doses showed a protective effect (p<0.05) against AST but in the case of ALT no ameliorating effect was found in either of the doses. Plasma total protein was decreased (p>0.05) but creatinine level was periodically increased in all As supplemented groups and vitamin E supplementation did not produce any protective effect. It can be concluded that arsenic exposure resulted in varying degree of changes in hemato-biochemical parameters and activities of antioxidant enzymes in goats but concomitant treatment with Vitamin E is partially helpful in reducing the burden of arsenic induced effect.",
Arsenic,1034096,"Arsenic exposure in a copper smelter as related to histological type of lung cancer Abstract: Tissue samples from lung cancer patients who had worked at a copper smelter and from controls were collected and classified by a panel of pathologists: 38% of the cancers were found to be adenocarcinomas, compared to 12% among the controls, a statistically significant difference (p less than 0.05). The predominance of adenocarcinomas was associated with arsenic exposure. This finding is not consistent with Kreyberg's hypothesis that small-cell undifferentiated and epidermoid carcinomas are the only type that increase in response to inhaled carcinogens [1962].",
Arsenic,1340120,"Urinary total arsenic and 8-hydroxydeoxyguanosine are associated with renal cell carcinoma in an area without obvious arsenic exposure Abstract: 8-Hydroxydeoxyguanosine (8-OHdG) is one of the most reliable and abundant markers of DNA damage. The study was designed to explore the relationship between urinary 8-OHdG and renal cell carcinoma (RCC) and to investigate whether individuals with a high level of 8-OHdG would have a modified odds ratio (OR) of arsenic-related RCC. This case-control study was conducted with 132 RCC patients and 245 age- and sex-matched controls from a hospital-based pool between November 2006 and May 2009. Pathological verification of RCC was completed by image-guided biopsy or surgical resection of renal tumors. Urinary 8-OHdG levels were determined using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Concentrations of urinary arsenic species, including inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), were determined by a high performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Level of urinary 8-OHdG was significantly associated with the OR of RCC in a dose-response relationship after multivariate adjustment. Urinary 8-OHdG was significantly related to urinary total arsenic. The greatest OR (3.50) was seen in the individuals with high urinary 8-OHdG and high urinary total arsenic. A trend test indicated that the OR of RCC was increased with one of these factors and was further increased with both (p=0.002). In conclusion, higher urinary 8-OHdG was a strong predictor of the RCC. High levels of 8-OHdG combined with urinary total arsenic might be indicative of arsenic-induced RCC.",
Arsenic,2149161,"A pilot study: The importance of inter-individual differences in inorganic arsenic metabolism for birth weight outcome Abstract: Inorganic arsenic (iAs) exposure is detrimental to birth outcome. We lack information regarding the potential for iAs metabolism to affect fetal growth. Our pilot study evaluated postpartum Romanian women with known birth weight outcome for differences in iAs metabolism. Subjects were chronically exposed to low-to-moderate drinking water iAs. We analyzed well water, arsenic metabolites in urine, and toenail arsenic. Urine iAs and metabolites, toenail iAs, and secondary methylation efficiency increased as an effect of exposure (p<0.001). Urine iAs and metabolites showed a significant interaction effect between exposure and birth weight. Moderately exposed women with low compared to normal birth weight outcome had greater metabolite excretion (p<0.03); 67% with low compared to 10% with normal birth weight outcome presented urine iAs >9?g/L (p=0.019). Metabolic partitioning of iAs toward excretion may impair fetal growth. Prospective studies on iAs excretion before and during pregnancy may provide a biomarker for poor fetal growth risk.",
Arsenic,1579368,"A new approach to determine the ratio of redox active species such as Se(IV)/Se(VI) and As(III)/As(V) in marine systems Abstract: The ratio of redox active species contributes to the researches about marine systems in many ways. Are marine systems reductant or oxidant? For this purpose, redox active species are analyzed by using high technology instrumental analyzers such as AAS, ICP, and HPLC. Then, all ion pair species are compared to each by calculating their ratios. These technologies are very expensive, and it takes long time to obtain the results. In this study, we suggested a basic method by using pH and Eh. Therefore, the Nernst equation expression was rearranged by using relative hydrogen (rH) and electrostatic activity coefficient (F(el)). Additionally, the ratio of the redox active ion pair species Se(IV)/Se(VI) and As(III)/As(V) was calculated.",
Arsenic,1372726,"Determination of arsenic in arsenic compounds and marine biological tissues using low volume microwave digestion and electrothermal atomic absorption spectrometry Abstract: Arsenic in marine biological tissues was measured by a low volume microwave dissolution technique and electrothermal atomic absorption spectrometry using a palladium and magnesium nitrate matrix modifier. Freeze dried samples (0.1 g dry wt) and 1 mL of nitric acid were placed into 7 mL screw top Teflon vessels and treated using a programmed three stage digestion. The effect of power and time parameters on arsenic recovery was examined. Preliminary studies showed that a short, maximum power first stage was beneficial for effective digestion, followed by cooling and an additional longer lower power stage. The first two microwave programme stages were kept consistent (600 W, 2 min; 0 W, 2 min) and the third stage was varied from 150 to 450 W over 15 to 60 min. Optimised microwave power and time conditions for arsenic recovery in marine reference materials were found to be 600 W, 2 min; 0 W, 2 min; 450 W, 45 min. Complete recovery of arsenic from a range of arsenic compounds and reference marine biological materials [National Institute of Standards and Technology (NIST) SRM 1566a Oyster Tissue; National Research Council Canada (NRCC) DORM-1 Dogfish Muscle; NRCC TORT-1 Lobster Hepatopancreas; NIST RM 50 Albacore Tuna; International Atomic Energy Agency (IAEA) MA-A-2 Fish Tissue; and AGAL-2 Shark Tissue] was achieved.?The effects of single modifier and modifier combinations of magnesium, copper, nickel and palladium nitrates on the arsenic atomic absorption signal magnitude were examined for the inorganic species of arsenic [As(III) as trichloride and As(V) as sodium arsenate], a phosphate spiked arsenite standard, organic arsenic compounds (arsenobetaine, arsenocholine, monomethylarsonic acid, dimethylarsinic acid and trimethylarsine oxide) and digests of reference marine biological materials. All digests were prepared using optimised microwave conditions and diluted to 50 mL to bring the concentration of As in the samples to within the normal working range of the standards and reduce the observed phosphate chemical interferences for full recovery of the analyte.?Three dimensional peak area surface response diagrams for Pd/Mg and Ni/Mg showed the following trends: (1) Mg alone recorded the highest signal magnitude (on average up to 17% higher than the optimum concentrations of Pd/Mg or Ni/Mg) for all arsenic compounds; (2) Mg alone exhibited poor modifying action for the digested marine tissues; (3) relative to the signal magnitude for Pd or Ni alone, the addition of Mg to the Pd or Ni modifier for arsenic compounds, in general, did not give a significant increase in signal magnitude; (4) in the case of digested marine tissues, the addition of Mg to Pd or Ni for analysis was essential for quantitative recovery of arsenic, providing the highest signal magnitude for the reference materials.?The addition of phosphate to arsenic standard compounds at concentrations that result in approximately 0.052 µmol P (1.5 µg P) on the platform caused a significant suppression of the As signal. This concentration of phosphate also significantly reduced the ability of Mg 2+ to act as a modifying agent, Mg no longer providing the highest signal magnitude for arsenic in arsenic compounds. The thermal stabilisation of As in the furnace was also reduced from 1200 to 900 °C. Pd and Ni were shown to provide higher signal magnitudes for phosphate spiked As standards, with the addition of Mg only increasing the signal magnitude by about 10% relative to Pd or Ni alone. The use of Cu, Ni and Pd was also found to increase significantly the thermal stabilisation of As in the furnace (1300 to 1400 °C). Higher atomisation temperatures were also required (up to 2200 °C). Examination of the Ni/Mg and Pd/Mg three dimensional peak area diagrams for digested marine tissues and the phosphate spiked As standard showed that both sample types exhibited similar optimum working ranges, with a smaller quantity of Pd being required to achieve the same modification as Ni. Cu/Mg did not appear to afford any advantage over Ni/Mg or Pd/Mg. In general, Pd/M gave a signal magnitude comparable to the equivalent Ni/Mg modifier for As, however, on the surface response diagrams, significantly larger optimal working regions for the marine tissue digests were recorded and Pd/Mg gave significantly higher signal magnitudes for the phosphate spiked standard. Pd is more effective in stabilising As in the presence of phosphate or in complex sample matrices and was therefore chosen as the preferred modifier to Ni. Solutions containing phosphate concentrations resulting in less than 0.0052 µmol P (0.15 µg P) on the platform did not exhibit any phosphorus interference. Digested tissues (0.1 g) needed to be diluted to 50 mL to lower the phosphate concentrations to these levels.?The optimum signal response for arsenic in biological tissues using As(III) as an inorganic standard was obtained with Pd/Mg at a level of 0.15 µmol Pd+0.4 µmol Mg (15.9 µg Pd+9.7 µg Mg) on the platform. This value was selected as a compromise between the optimum amount of modifier needed for the stabilisation of arsenic compounds in aqueous standards and that required by the digested marine tissues.",
Arsenic,1026600,"Speciation of arsenic compounds in urine from occupationally unexposed and exposed persons in the U.K. using a routine LC-ICP-MS method Abstract: This paper describes a routine, robust, and reproducible liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) speciation method for five arsenic compounds [arsenobetaine (AB), arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)] in urine. Concentrations of these arsenic species in urine samples are reported in two sets of non-occupationally exposed controls with one set having consumed fish within 24 h (n = 31) and the other not having consumed fish for 48 h (n = 34). Arsenic species in urine samples from workers in both the timber treatment industry (n = 49) and semiconductor industry (n = 46) are also reported. The arsenic content in all of the samples was also determined using hydride-generation coupled with ICP-MS. The results show that urine samples from people not occupationally exposed to arsenic contain low levels of DMA, MMA, and AB and that only urine from smokers contained any inorganic arsenic. Consumption of seafood was seen to significantly increase the levels of AB and DMA in the unexposed persons. Urine samples from the semiconductor workers exhibited significantly higher levels of arsenite, arsenate, and DMA than the unexposed samples. The urine samples from timber treatment workers exhibited significantly higher levels of four arsenic species (not AB) than those observed in both the control groups and the semi-conductor workers.",
Arsenic,735103,"Intracellular redox imbalance and extracellular amino acid metabolic abnormality contribute to arsenic-induced developmental retardation in mouse preimplantation embryos Abstract: Inorganic arsenic, an environmental contaminant, is known to cause cancer, developmental retardation, and many other serious diseases. Previous researches have shown that arsenic exerts its toxicity partially through generating reactive oxygen species (ROS). However, it is still not well understood how ROS links arsenic exposure to developmental retardation of preimplantation embryo. Here we demonstrate that high-level arsenite induces severe redox imbalance by decreasing the levels of glutathione and increasing the levels of ROS through the oxidative stress adaptor p66Shc, which induces apoptosis by activating the cytochrome c-caspase. In addition, low-level arsenite seriously perturbs the metabolism of extracellular amino acid, especially that of the cytotoxic and antioxidative amino acids in preimplantation embryos, may also be the reason for developmental delay. Furthermore, an antioxidant, N-acetyl-L-cysteine, improves the development of arsenite-exposed embryos by reducing intracellular ROS and adjusting amino acid metabolism, suggesting that increasing the intracellular antioxidant level may have preventive or therapeutic effects on arsenic-induced embryonic toxicity. In conclusion, we suggest that p66Shc-linked redox imbalance and abnormal extracellular amino acid metabolism mediate arsenite-induced embryonic retardation.",
Arsenic,628450,"Expression cloning for arsenite-resistance resulted in isolation of tumor-suppressor fau cDNA: Possible involvement of the ubiquitin system in arsenic carcinogenesis Abstract: Arsenic is a human carcinogen whose mechanism of action is unknown. Previously, this laboratory demonstrated that arsenite acts as a comutagen by interfering with DNA repair, although a specific DNA repair enzyme sensitive to arsenite has not been identified. A number of stable arsenite-sensitive and arsenite-resistant sublines of Chinese hamster V79 cells have now been isolated. In order to gain understanding of possible targets for arsenite's action, one arsenite-resistant subline, As/R28A, was chosen as a donor for a cDNA expression library. The library from arsenite-induced As/R28A cells was transfected into arsenite-sensitive As/S5 cells, and transfectants were selected for arsenite-resistance. Two cDNAs, asr1 and asr2, which confer arsenite resistance to arsenite-hypersensitive As/S5 cells as well as to wild-type cells, were isolated. asr1 shows almost complete homology with the rat fau gene, a tumor suppressor gene which contains a ubiquitin-like region fused to S30 ribosomal protein. Arsenite was previously shown to inhibit ubiquitin-dependent proteolysis. These results suggest that the tumor suppressor fau gene product or some other aspect of the ubiquitin system may be a target for arsenic toxicity and that disruption of the ubiquitin system may contribute to the genotoxicity and carcinogenicity of arsenite.",
Arsenic,81896,"Induction of anchorage independence in human diploid foreskin fibroblasts by carcinogenic metal salts Abstract: We studied whether arsenic, nickel, and chromium compounds that are human carcinogens could induce transformation of cultured primary human diploid foreskin cells (HFC). All nickel compounds tested, PbCrO4, K2Cr2O7, CrO3, Na2HAsO4, NaAsO2, and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) caused significant (p = 0.001) dose-dependent inductions of anchorage-independent colonies in HFC. KH2AsO4, CaCl2, MnCl2, and Hg(CH3CO2)2 did not induce anchorage independence. Optimal expression times for induction of anchorage independence in HFC were observed as early as 11 days following treatment with MNNG, Ni3S2, Ni(C2H3O2), or NiSO4. Cell strains derived from anchorage-independent colonies showed 33 to 429-fold higher plating efficiencies in soft agar than parental populations, and the anchorage-independent phenotype was stable for eight passages, at which time cells senesced. Anchorage-independent cell strains derived from metal salt-treated cells were not resistant to the cytotoxicity of metal salts, indicating metal salts induced rather than selected for anchorage independence. Nine of 10 cell strains derived from metal compound- or MNNG-induced anchorage-independent colonies displayed the same or lower saturation densities than untreated human fibroblasts. None of these cell strains escaped senescence or showed definitive morphological transformation. MNNG (1 micrograms/ml) induced anchorage independence and mutation to ouabain resistance and 6-thioguanine resistance in HFC, but concentrations of Ni2S3 that induced anchorage independence did not induce mutation at either locus in HFC. These results demonstrate that carcinogenic metal salts induce stable anchorage independence early in human diploid foreskin fibroblasts, and this anchorage independence is independent of other in vitro markers of fibroblast transformation, such as focus formation or immortality. Metal salt induction of anchorage independence can now be used as an assay to study mechanisms of genotoxicity exerted by carcinogenic metal compounds in human cells.",
Arsenic,1509343,"Nanoparticle-loaded multifunctional natural seed gel-bits for efficient water purification Abstract: In this work we demonstrate the use of natural seed based hydrogel bits as robust, recoverable and recyclable support for nanoparticulate catalytic media for multipurpose water purification application. We show that the inexpensive and easily available natural seeds sabja (Ocimum basilicum), which can absorb water to about 30 times their weight can be easily loaded with nanoparticles of functional metal oxides such as visible light photo-catalyst N-doped TiO2 or magnetite (Fe3O4) for effective multiple water purification objectives such as efficient photocatalytic degradation of toxins or bacteria, heavy metal ion (As3+, Cr6+, Pb2+, Cd2+) removal or simple particulate filtering. Indeed, innovative nanoparticle loading strategy can be used to load organic and inorganic materials concurrently, sequentially or simultaneously on the gel-bits while they swell in the process of water absorption. Interestingly the gel-bits maintain their individual identity without agglomeration or fusing, and given their swollen size of about few millimetres they can be easily separated out by simple cloth or millimetre scale filtering. This alleviates the difficulties associated with separating nanoparticles dispersed in the media directly for photocatalytic or other purification purposes. With magnetic nanoparticle co-loading they can also be separated out by magnetic field, which can be beneficial in situations wherein filtering may not be an easy option. It is useful to mention that the same seed gel-bits can also serve as particle size filters for specific applications.",
Arsenic,1378346,"Non-carcinogenic effects of inorganic arsenic Abstract: BIOSIS COPYRIGHT: BIOL ABS. This review will focus primarily on the effects of the inorganic arsenicals (arsenate and arsenite forms) that are present in drinking water. They are acutely toxic to both humans and animals, an effect that may be related to their bioavailability. In humans, arsenicals have been reported to cause dermatitis and mucous membrane irritation upon exposure. They have also been reported to cause skin lesions and peripheral neurotoxicity in smelter workers and in patients treated with Fowler's Solution. When humans are exposed to arsenic in drinking water, effects much as hyperkeratosis, electromyographic abnormalities and vascular effects have been reported. In experimental animals, arsenic has been demonstrated to affect the liver and kidneys. In mice, arsenic has also been reported to decrease the animal's resistance to certain viral infections. The arsenite (+3) and arsenate (+5) forms have different modes of action. Arsenite binds to sulphhydryl groups and has been report",
Arsenic,628597,"Monomethylarsonous acid inhibits endothelial nitric oxide synthase activity Abstract: Inorganic arsenic undergoes extensive reduction and oxidative methylation in cells to yield a reactive metabolite of inorganic arsenic monomethylarsonous acid (MMAIII), which has a high reactivity toward vicinal thiols. Our epidemiological study in an endemic area of chronic arsenic poisoning and in experiments with rabbits exposed to arsenic revealed that arsenic exposure results in a reduction of systemic nitric oxide (NO) production. In this study, we examined the effect of MMAIII on endothelial NO synthase (eNOS) activity. With the membrane fraction of bovine aortic endothelial cells (BAEC), it was found that MMAIII with an IC50 value of 2.1 ?M was a potent inhibitor of eNOS, whereas inorganic arsenic and their methylated metabolites had no effect on eNOS activity. Interestingly, addition of dithiothreitol markedly blocked the MMAIII-induced inhibition of eNOS activity. This report is the first to suggest that MMAIII interacts with eNOS protein through presumably vicinal thiols, leading to decreased eNOS activity.",
Arsenic,1340316,"Stress granules contribute to ?-globin homeostasis in differentiating erythroid cells Abstract: Hemoglobin is the major biosynthetic product of developing erythroid cells. Assembly of hemoglobin requires the balanced production of globin proteins and the oxygen-carrying heme moiety. The heme-regulated inhibitor kinase (HRI) participates in this process by phosphorylating eIF2? and inhibiting the translation of globin proteins when levels of free heme are limiting. HRI is also activated in erythroid cells subjected to oxidative stress. Phospho-eIF2?-mediated translational repression induces the assembly of stress granules (SG), cytoplasmic foci that harbor untranslated mRNAs and promote the survival of cells subjected to adverse environmental conditions. We have found that differentiating erythroid, but not myelomonocytic or megakaryocytic, murine and human progenitor cells assemble SGs, in vitro and in vivo. Targeted knockdown of HRI or G3BP, a protein required for SG assembly, inhibits spontaneous and arsenite-induced assembly of SGs in erythroid progenitor cells. This is accompanied by reduced ?-globin production and increased apoptosis suggesting that G3BP+ SGs facilitate the survival of developing erythroid cells.",
Arsenic,1339169,"Groundwater quality in Imphal West district, Manipur, India, with multivariate statistical analysis of data Abstract: The aim of this paper was to analyze the groundwater quality of Imphal West district, Manipur, India, and assess its suitability for drinking, domestic, and agricultural use. Eighteen physico-chemical variables were analyzed in groundwater from 30 different hand-operated tube wells in urban, suburban, and rural areas in two seasons. The data were subjected to uni-, bi-, and multivariate statistical analysis, the latter comprising cluster analysis (CA), principal component analysis (PCA), and factor analysis (FA). Arsenic concentrations exceed the Indian standard in 23.3 % and the WHO limit in 73.3 % of the groundwater sources with only 26.7 % in the acceptable range. Several variables like iron, chloride, sodium, sulfate, total dissolved solids, and turbidity are also beyond their desirable limits for drinking water in a number of sites. Sodium concentrations and sodium absorption ratio (SAR) are both high to render the water from the majority of the sources unsuitable for agricultural use. Multivariate statistical techniques, especially varimax rotation of PCA data helped to bring to focus the hidden yet important variables and understand their roles in influencing groundwater quality. Widespread arsenic contamination and high sodium concentration of groundwater pose formidable constraints towards its exploitation for drinking and other domestic and agricultural use in the study area, although urban anthropogenic impacts are not yet pronounced.",
Arsenic,1762779,"Heavy metal pollution of surface water sources of Konya Basin Abstract: Surface water continuously exposed to numerous environmental pollutants among which the most potentially hazardous are toxic chlorinated compounds, heavy metals, residual chemicals and radioactive compounds. Heavy metals can enter waters through natural and anthropogenic sources. Most heavy metal contaminants originate from different natural sources such as magmatic, sedimentary, and metamorphic rocks. The origin of heavy metals in surface and groundwater are also from anthropogenic sources due to human activities such as industrial production and agriculture. Many of heavy metals have been detected in different environmental compartments. Konya (in Turkey) watershed is a closed basin and has 4.52 billion m3 water capacity. Surface water sources are being polluted by anthropogenic sources such as domestic, agricultural and industrial activities. The determination of the water quality of surface water sources in Konya closed basin is very important. Because Konya closed basin is the biggest closed basin in Turkey and larger part of Turkey is in semi-arid climate area. In this work 32 monitoring stations were selected for investigation of heavy metal pollution within the closed basin. Water samples collected from these monitoring stations were analysed for arsenic (As), cadmium (Cd), lead (Pb), copper (Cu), chromium (Cr), cobalt (Co), nickel (Ni), zinc (Zn), iron (Fe), manganese (Mn), aluminum (Al), beryllium (Be), selenium (Se) using Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The results obtained were compared with drinking and irrigation waters guidance values given by the Turkish Regulations, the European Community Council Directive 98/83/EC, US Environmental Protection Agency and World Health Organization.",
Arsenic,627042,"Skin cancer risk in relation to toenail arsenic concentrations in a US population-based case-control study Abstract: Arsenic is a known carcinogen specifically linked to skin cancer occurrence in regions with highly contaminated drinking water or in individuals who took arsenic-containing medicines. Presently, it is unknown whether such effects occur at environmental levels found in the United States. To address this question, the authors used data collected on 587 basal cell and 284 squamous cell skin cancer cases and 524 controls interviewed as part of a case-control study conducted in New Hampshire between 1993 and 1996. Arsenic was determined in toenail clippings using instrumental neutron activation analysis. The odds ratios for squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) were close to unity in all but the highest category. Among individuals with toenail arsenic concentrations above the 97th percentile, the adjusted odds ratios were 2.07 (95% confidence interval (CI): 0.92, 4.66) for SCC and 1.44 (95% CI: 0.74, 2.81) for BCC, compared with those with concentrations at or below the median. While the risks of SCC and BCC did not appear elevated at the toenail arsenic concentrations detected in most study subjects, the authors cannot exclude the possibility of a dose-related increase at the highest levels of exposure experienced in the New Hampshire population.",
Arsenic,1350940,"ARSENIC, BISMUTH, COPPER, LEAD, NICKEL, AND SELENIUM IN SOME BIOLOGICAL SAMPLES - DETERMINATION BY GRAPHITE-FURNACE ATOMIZATION-ATOMIC ABSORPTION SPECTROMETRY Abstract: ",
Arsenic,627725,"Analysis of T-cell proliferation and cytokine secretion in the individuals exposed to arsenic Abstract: Over six million people in nine districts of West Bengal, India are exposed to very high levels of arsenic primarily through their drinking water. More than 300,000 people showed arsenic-induced skin lesions in these districts. This is regarded as the greatest arsenic calamity in the world. Chronic arsenicosis causes varied dermatological signs ranging from pigmentation changes, hyperkeratosis to non-melanocytic cancer of skin, and also malignancies in different internal organs. Higher incidences of opportunistic infections are found in the arsenic-exposed individuals, indicating that their immune systems may be impaired somehow. We have thus investigated the effect of arsenic on T-cell proliferation and cytokine secretion in 20 individuals with arsenic-induced skin lesions and compared the results with 18 arsenic-unexposed individuals. A marked dose-dependent suppression of Concanavalin A (Con A) induced T-cell proliferation was observed in the arsenic-exposed individuals compared with the unexposed (P < 0.001) individuals. This correlated with a significant decrease in the levels of secreted cytokines by the T cells (TNF-alpha, IFN-gamma, IL2, IL10, IL5, and IL4) in the exposed individuals (P < 0.001). Thus it can be inferred that arsenic exposure can cause immunosuppression in humans.",
Arsenic,1032666,"Alterations in lipid-linked oligosaccharide metabolism in human melanoma cells concomitant with induction of stress proteins Abstract: Challenge of human A375 melanoma cells with sodium arsenite induced the synthesis of stress proteins and stimulated [3H]mannose incorporation into a novel component migrating on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent molecular mass of 14 kDa (designated M14). Enhanced M14 expression was elicited by heavy metals (zinc, copper, cadmium, and nickel), thiol-reactive agents (iodoacetamide and auranofin), and hyperthermia. The kinetics of M14 induction and recovery from stress were similar to those of the stress proteins, but M14 half-life was only 15 min. Incorporation of [3H]mannose into M14 was inhibited by tunicamycin but not by cycloheximide or actinomycin D. M14 was metabolically labeled with [32P]orthophosphate but not by [35S] methionine or [3H]asparagine. Further studies revealed that M14 was selectively soluble in chloroform/methanol/water (10:10:3) and sensitive to both endo-beta-N-acetylglucosaminidase H digestion and mild acid hydrolysis. The latter released a water-soluble mannose-labeled moiety which eluted from Bio-Gel P-6 in a manner similar to Glc3Man9GlcNAc2. Together, these data suggest that M14 is a lipid-oligosaccharide intermediate of N-linked protein glycosylation and that enhanced expression of this class of molecule in response to chemical insults and hyperthermia is a newly described cellular reaction to stress.",
Arsenic,1579285,"High-temperature thermomagnetic properties of vivianite nodules, Lake El'gygytgyn, Northeast Russia Abstract: ",
Arsenic,1032555,"Elevation of glutathione levels and glutathione S-transferase activity in arsenic-resistant Chinese hamster ovary cells Abstract: Arsenic-resistant Chinese hamster ovary (CHO) cells were established by progressively increasing the concentration of sodium arsenite in culture medium. One of the resistant clones, SA7, was also cross-resistant to As(V), Zn, Fe(II), Co, and Hg. The susceptibilities to sodium arsenite in parental CHO cells, revertant SA7N cells, and resistant SA7 cells were correlated with their intracellular glutathione (GSH) levels and glutathione S-transferase (GST) activity. The resistance in SA7 cells was diminished by depletion of GSH in cells after treatment with buthionine sulfoximine. Furthermore, after reexposure of revertant SA7N cells to sodium arsenite, the intracellular GSH levels, GST activity, and resistance to sodium arsenite were raised to the same levels as SA7 cells. These data indicate that the elevation of intracellular GSH levels and GST activity in SA7 cells may be responsible for the resistance to arsenite. A p25 protein, which could be a monomer subunit of GST, accumulated in SA7 cells. In addition, an outward transport inhibitor, verapamil, indiscriminately increased the arsenite toxicity in resistant and parental cells.",
Arsenic,1356902,"Drinking Water Economic Analysis (EA): The Arsenic Cessation Lag Model Abstract: The 1996 Safe Drinking Water Act Amendments require an EA for all regulations. The EA examines treatment and analytical costs and public health benefits. Included in the public health benefits section is a cancer latency analysis to account for decreased future cancer risk after current exposure reduction. If public health benefits are discounted due to disease developmental latency, then credit should also be applied to acknowledge the proportional health benefits accrued from immediate exposure reduction. A mathematical model is required to describe the cessation lag, or in other words, how the attributable cancer case rate moves from its current assumed steady state toward its new lower limit. To that end, we used the available Arsenic data in an attempt to model a chemical-specific cessation lag. Due to the lack of sufficient data for Arsenic, we decided to use data on smoking from Hrubec and McLaughlin (1997) to model the rate at which the new limit is approached. Key assumptions in this comparison include: 1. the mode(s) of action is/are similar, and 2. the specific cessation lag for lung cancer due to smoking approximates that for all cancers associated with ingested arsenic exposure. This model approximates that at 2, 10 and 20 years post-exposure reduction of As exposures in drinking water from 50 ppb to 10 ppb, there is a corresponding 41%, 83% and 90% maximum reduction in lung cancer risk, respectively. This model can be applied to other exposure reduction situations when relative risks are known for individuals at both high (pre-regulation) and low (post-regulation) exposure conditions.",
Arsenic,1508626,"A cross-sectional survey on knowledge and perceptions of health risks associated with arsenic and mercury contamination from artisanal gold mining in Tanzania Abstract: <strong>BACKGROUND: </strong>An estimated 0.5 to 1.5 million informal miners, of whom 30-50% are women, rely on artisanal mining for their livelihood in Tanzania. Mercury, used in the processing gold ore, and arsenic, which is a constituent of some ores, are common occupational exposures that frequently result in widespread environmental contamination. Frequently, the mining activities are conducted haphazardly without regard for environmental, occupational, or community exposure. The primary objective of this study was to assess community risk knowledge and perception of potential mercury and arsenic toxicity and/or exposure from artisanal gold mining in Rwamagasa in northwestern Tanzania.<br /><br /><strong>METHODS: </strong>A cross-sectional survey of respondents in five sub-villages in the Rwamagasa Village located in Geita District in northwestern Tanzania near Lake Victoria was conducted. This area has a history of artisanal gold mining and many of the population continue to work as miners. Using a clustered random selection approach for recruitment, a total of 160 individuals over 18 years of age completed a structured interview.<br /><br /><strong>RESULTS: </strong>The interviews revealed wide variations in knowledge and risk perceptions concerning mercury and arsenic exposure, with 40.6% (n=65) and 89.4% (n=143) not aware of the health effects of mercury and arsenic exposure respectively. Males were significantly more knowledgeable (n=59, 36.9%) than females (n=36, 22.5%) with regard to mercury (x2=3.99, p&lt;0.05). An individual's occupation category was associated with level of knowledge (x2=22.82, p=&lt;0.001). Individuals involved in mining (n=63, 73.2%) were more knowledgeable about the negative health effects of mercury than individuals in other occupations. Of the few individuals (n=17, 10.6%) who knew about arsenic toxicity, the majority (n=10, 58.8%) were miners.<br /><br /><strong>CONCLUSIONS: </strong>The knowledge of individuals living in Rwamagasa, Tanzania, an area with a history of artisanal gold mining, varied widely with regard to the health hazards of mercury and arsenic. In these communities there was limited awareness of the threats to health associated with exposure to mercury and arsenic. This lack of knowledge, combined with minimal environmental monitoring and controlled waste management practices, highlights the need for health education, surveillance, and policy changes.",
Arsenic,786655,"Arsenite induces cell transformation by reactive oxygen species, AKT, ERK1/2, and p70S6K1 Abstract: Arsenic is naturally occurring element that exists in both organic and inorganic formulations. The inorganic form arsenite has a positive association with development of multiple cancer types. There are significant populations throughout the world with high exposure to arsenite via drinking water. Thus, human exposure to arsenic has become a significant public health problem. Recent evidence suggests that reactive oxygen species (ROS) mediate multiple changes to cell behavior after acute arsenic exposure, including activation of proliferative signaling and angiogenesis. However, the role of ROS is mediating cell transformation by chronic arsenic exposure is unknown. We found that cells chronically exposed to sodium arsenite increased proliferation and gained anchorage-independent growth. This cell transformation phenotype required constitutive activation of AKT, ERK1/2, mTOR, and p70S6K1. We also observed these cells constitutively produce ROS, which was required for the constitutive activation of AKT, ERK1/2, mTOR, and p70S6K1. Suppression of ROS levels by forced expression of catalase also reduced cell proliferation and anchorage-independent growth. These results indicate cell transformation induced by chronic arsenic exposure is mediated by increased cellular levels of ROS, which mediates activation of AKT, ERK1/2, and p70S6K1.",
Arsenic,627011,"Arsenic trioxide selectively induces acute promyelocytic leukemia cell apoptosis via a hydrogen peroxide-dependent pathway Abstract: Low concentrations of As(2)O(3) ( < /=1 micromol/L) induce long-lasting remission in patients with acute promyelocytic leukemia (APL) without significant myelosuppressive side effects. Several groups, including ours, have shown that 0.5 to 1 micromol/L As(2)O(3) induces apoptosis in APL-derived NB4 cells, whereas other leukemic cells are resistant to As(2)O(3) or undergo apoptosis only in response to greater than 2 micromol/L As(2)O(3). In this report, we show that the ability of As(2)O(3) to induce apoptosis in leukemic cells is dependent on the activity of the enzymes that regulate cellular H(2)O(2) content. Thus, NB4 cells have relatively low levels of glutathione peroxidase (GPx) and catalase and have a constitutively higher H(2)O(2) content than U937 monocytic leukemia cells. Glutathione-S-transferase pi (GSTpi), which is important for cellular efflux of As(2)O(3), is also low in NB4 cells. Moreover, As(2)O(3) further inhibits GPX activity and increases cellular H(2)O(2) content in NB4 but not in U937 cells. Selenite pretreatment of NB4 cells increases the activity of GPX, lowers cellular H(2)O(2) levels, and renders NB4 cells resistant to 1 micromol/L As(2)O(3). In contrast, concentrations of As(2)O(3) that alone are not capable of inducing apoptosis in NB4 cells induce apoptosis in the presence of the GPx inhibitor mercaptosuccinic acid. Similar effects are observed by modulating the activity of catalase with its inhibitor, aminotriazol. More important from a therapeutic point of view, U937 and HL-60 cells, which require high concentrations of As(2)O(3) to undergo apoptosis, become sensitive to low, clinically acceptable concentrations of As(2)O(3) when cotreated with these GPx and catalase inhibitors. The induction of apoptosis by As(2)O(3) involves an early decrease in cellular mitochondrial membrane potential and increase in H(2)O(2) content, followed by cytochrome c release, caspase 3 activation, DNA fragmentation, and the classic morphologic changes of apoptosis.",
Arsenic,1015769,"Inorganic arsenic contents in rice-based infant foods from Spain, UK, China and USA Abstract: Spanish gluten-free rice, cereals with gluten, and pureed baby foods were analysed for total (t-As) and inorganic As (i-As) using ICP-MS and HPLC-ICP-MS, respectively. Besides, pure infant rice from China, USA, UK and Spain were also analysed. The i-As contents were significantly higher in gluten-free rice than in cereals mixtures with gluten, placing infants with celiac disease at high risk. All rice-based products displayed a high i-As content, with values being above 60% of the t-As content and the remainder being dimethylarsinic acid (DMA). Approximately 77% of the pure infant rice samples showed contents below 150 ?g kg(-1) (Chinese limit). When daily intake of i-As by infants (4-12 months) was estimated and expressed on a bodyweight basis (?g d(-1) kg(-1)), it was higher in all infants aged 8-12 months than drinking water maximum exposures predicted for adults (assuming 1 L consumption per day for a 10 ?g L(-1) standard).",
Arsenic,67328,"Ingested arsenic, keratoses, and bladder cancer Abstract: A cohort of 478 patients treated with Fowler's solution (potassium arsenite) in Lancashire, England, during the penod 1945–1969 and previously followed until January 1, 1980, was followed for an additional 11 years. A significant excess of bladder cancer mortality occurred (observed/expected ratio = 5/1.6; p = 0.05). No excess was found for other causes of death. In a subcohort of 142 patients examined for signs of arsenicism around 1970, all 11 subsequent cancer deaths occurred in those with signs of arsenicism (p = 0.0009).",
Arsenic,2149182,"?LC-ICP-MS Determinations of Unexposed UK Urinary Arsenic Speciation Reference Values Abstract: This study provides background levels for five arsenic species in urine, based on urinary data obtained from 95 nonoccupationally exposed volunteers based in the UK. Using a novel, sensitive, robust and reliable speciation methodology, five species of arsenic (arsenobetaine [AB], arsenite [As(3+)], arsenate [As(5+)], monomethylarsonic acid [MMA(5+)] and dimethylarsinic acid [DMA(5+)]) were determined in urine samples collected from 95 adults. The analytical instrumentation used to analyze the urine samples was a hyphenated micro liquid chromatography (?LC) system coupled to an inductively coupled plasma mass spectrometry (ICP-MS). Separation was achieved using an anion exchange micro-sized column. The results presented give the 95th percentile of concentrations, both uncorrected for creatinine (µg/L) and creatinine corrected (µmol/mol) in urine for the 95 volunteers. Statistical analysis was performed on the dataset using a Bayesian model to determine and quantify effects of gender, smoking and diet. The statistical results show that the consumption of fish, shellfish and red wine has a significant elevating effect on AB, DMA and MMA urinary concentrations; however, no significant effect was observed for smoking. The regression model results indicate that creatinine correction was effective for arsenic species As(3+), MMA, DMA and AB. The background levels established here can be used as reference values to help aid interpretation of arsenic speciation results and better assess exposure.",
Arsenic,657043,"Cytoprotective Activity of Glycyrrhizae radix Extract Against Arsenite-induced Cytotoxicity Abstract: Licorice, Glycyrrhizae radix, is one of the herbal medicines in East Asia that has been commonly used for treating various diseases, including stomach disorders. This study investigated the effect of licorice on arsenite (As)-induced cytotoxicity in H4IIE cells, a rat hepatocyte-derived cell line. Cell viability was significantly diminished in As-treated H4IIE cells in a time and concentration-dependent manner. Furthermore, results from flow cytometric assay and DNA laddering in H4IIE cells showed that As treatment induced apoptotic cell death by activating caspase-3. Licorice (0.1 and 1.0 mg ml(-1)) treatment significantly inhibited cell death and the activity of caspase-3 in response to As exposure. These results demonstrate that licorice induced a cytoprotective effect against As-induced cell death by inhibition of caspase-3.",
Arsenic,1247858,"Feedback inhibition by thiols outranks glutathione depletion: a luciferase-based screen reveals glutathione-deficient ?-ECS and glutathione synthetase mutants impaired in cadmium-induced sulfate assimilation Abstract: Plants exposed to heavy metals rapidly induce changes in gene expression that activate and enhance detoxification mechanisms, including toxic-metal chelation and the scavenging of reactive oxygen species. However, the mechanisms mediating toxic heavy metal-induced gene expression remain largely unknown. To genetically elucidate cadmium-specific transcriptional responses in Arabidopsis, we designed a genetic screen based on the activation of a cadmium-inducible reporter gene. Microarray studies identified a high-affinity sulfate transporter (SULTR1;2) among the most robust and rapid cadmium-inducible transcripts. The SULTR1;2 promoter (2.2?kb) was fused with the firefly luciferase reporter gene to quantitatively report the transcriptional response of plants exposed to cadmium. Stably transformed luciferase reporter lines were ethyl methanesulfonate (EMS) mutagenized, and stable M(2) seedlings were screened for an abnormal luciferase response during exposure to cadmium. The screen identified non-allelic mutant lines that fell into one of three categories: (i) super response to cadmium (SRC) mutants; (ii) constitutive response to cadmium (CRC) mutants; or (iii) non-response and reduced response to cadmium (NRC) mutants. Two nrc mutants, nrc1 and nrc2, were mapped, cloned and further characterized. The nrc1 mutation was mapped to the ?-glutamylcysteine synthetase gene and the nrc2 mutation was identified as the first viable recessive mutant allele in the glutathione synthetase gene. Moreover, genetic, HPLC mass spectrometry, and gene expression analysis of the nrc1 and nrc2 mutants, revealed that intracellular glutathione depletion alone would be insufficient to induce gene expression of sulfate uptake and assimilation mechanisms. Our results modify the glutathione-depletion driven model for sulfate assimilation gene induction during cadmium stress, and suggest that an enhanced oxidative state and depletion of upstream thiols, in addition to glutathione depletion, are necessary to induce the transcription of sulfate assimilation genes during early cadmium stress.",
Arsenic,1252104,"Arsenicosis in a village in Bangladesh Abstract: The study was carried out in a village in Jessore district, Bangladesh, to identify the epidemiological characteristics of arsenicosis. Eighty-seven per cent of the tubewells had arsenic concentration more than the WHO maximum permissible limit of 0.05 mg l(-1). The mean arsenic concentration was 0.240 mg l(-1) and the maximum concentration was 1.371 mg l(-1). Of the total 3606 villagers, 10% (363) were found to be suffering from arsenicosis. Most of the arsenicosis patients were between 10 to 39 years of age. There were more male patients (52.6%). There were no patients among villagers who consumed tubewell water having arsenic levels less than 0.082 mg l(-1). The majority (93.4%) of the patients were in the first and second stage of arsenicosis. With increasing exposure to arsenic, a simultaneous increase in the severity of clinical manifestations of arsenicosis was observed (F=43.699; p=0.000). The time-weighted arsenic exposure varied from 0.248 to 5.482 mg day(-1) and the mean was 1.918 mg day(-1). Melanosis was present in almost all the patient (99.5%) and keratosis was present in 68.9%. Cancer (basal cell epithelioma) was present in three (0.8%) patients. The duration of clinical manifestations of arsenicosis varied from 1 to 12 years and the majority were suffering for 4-6 years.",
Arsenic,627517,"Opposite effect of ERK1/2 and JNK on p53-independent p21WAF1/CIP1 activation involved in the arsenic trioxide-induced human epidermoid carcinoma A431 cellular cytotoxicity Abstract: While arsenic trioxide (As2O3) is an infamous carcinogen, it is also an effective chemotherapeutic agent for acute promyelocytic leukemia and some solid tumors. In human epidermoid carcinoma A431 cells, we found that As2O3 induced cell death in time- and dose-dependent manners. Similarly, dependent regulation of the p21WAF1/CIP1 (p21) promoter, mRNA synthesis, and resultant protein expression was also observed. Additionally, transfection of a small interfering RNA of p21 could block the As2O3-induced cell growth arrest. The As2O3-induced p21 activation was attenuated by inhibitors of EGFR and MEK in a dose-dependent manner. Using a reporter assay, we demonstrated the involvement of the EGFR-Ras-Raf-ERK1/2 pathway in the promoter activation. In contrast, JNK inhibitor enhanced the As2O3-induced p21 activation, also in a dose-dependent fashion. Over-expression of a dominant negative JNK plasmid likewise also enhanced this activation. Furthermore, MEK inhibitor attenuated the anti-tumor effect of As2O3. In contrast, in combination with JNK inhibitor and As2O3 enhanced cellular cytotoxicity. Therefore, we conclude that in A431 cells the ERK1/2 and JNK pathways might differentially contribute to As2O3-induced p21 expression and then due to cellular cytotoxicity.",
Arsenic,1340122,"Effects of three low-molecular-weight organic acids (LMWOAs) and pH on the mobilization of arsenic and heavy metals (Cu, Pb, and Zn) from mine tailings Abstract: Natural organic acids may play an important role in influencing the mobility of toxic contaminants in the environment. The mobilization of arsenic (As) and heavy metals from an oxidized Pb-Zn mine tailings sample in the presence of three low-molecular-weight organic acids, aspartic acid, cysteine, and succinic acid, was investigated at a mass ratio of 10 mg organic additive/g mine tailings in this study. The effect of pH was also evaluated. The mine tailings sample, containing elevated levels of As (2,180 mg/kg), copper (Cu, 1,100 mg/kg), lead (Pb, 12,860 mg/kg), and zinc (Zn, 5,075 mg/kg), was collected from Bathurst, New Brunswick, Canada. It was found that the organic additives inhibited As and heavy metal mobilization under acidic conditions (at pH 3 or 5), but enhanced it under neutral to alkaline conditions (at pH above 7) through forming aqueous organic complexes. At pH 11, As, Cu, Pb, and Zn were mobilized mostly by the organic additives, 45, 46, 1,660, and 128 mg/kg by aspartic acid, 31, 28, 1,040, and 112 mg/kg by succinic acid, and 53, 38, 2,020, and 150 mg/kg by cysteine, respectively, whereas those by distilled water were 6, 16, 260, and 52 mg/kg, respectively. It was also found that the mobilization of As and the heavy metals was closely correlated, and both were closely correlated to Fe mobilization. Arsenic mobilization by the three LMWOAs was found to be consistent with the order of the stability of Fe-, Cu-, Pb-, and Zn-organic ligand complexes. The organic acids might be used potentially in the natural attenuation and remediation of As and heavy metal-contaminated sites.",
Arsenic,1794781,"Fluoride free new nano-particles-Mn-Biotite synthesis for removal of some toxic heavy metals, Th(IV) and U(VI) from aqueous solutions Abstract: The present paper aims to synthesize new family of fluoride free Mn- Biotite type having the optimized formula NaMn/sub 2.5/(Al,Si)/sub 4/O/sub 10/(OH)/sub 2/. The free fluoride Mn- Biotite was prepared carefully by using solid- state reaction technique using nominal compositions of individual oxides in the main formula for the potential removal of some heavy metals and some radioactive elements from aqueous solution. The crystal structure of Mn-Biotite was well characterized via powder X-ray diffraction (XRD). The particle size was estimated and found to be 54 nm. Analysis of XRD profile indicated that Mn- Biotite is belonging mainly to the monoclinic crystal structure. Infrared spectroscopy (IR) showed the most intensive absorption peaks for monoclinic phase observed at 3420, 2360, 1620, 1440cm/sup -1/. Furthermore the morphological microstructure was investigated by SE-microscopy (SEM), the estimated grain size was found to be in between (0.8-7.7) micro m. Electron spin resonance (ESR) proved that Mn-biotite has paramagnetic behavior. Also DC- electrical conductivity and TGA were investigated. In conclusion results suggest that the synthesized Mn- biotite can be used as good ion exchanger with high performance to remove heavy metals and some radioactive species from wastewater.",
Arsenic,2064265,"Speciation and distribution of arsenic in the non-hyperaccumulator macrophyte Ceratophyllum demersum L Abstract: Although arsenic is a common pollutant worldwide, many questions about As metabolism in non-hyperaccumulator plants remain. Concentration and tissue dependent speciation and distribution of arsenic was analysed in the aquatic plant Ceratophyllum demersum to understand arsenic metabolism in non-hyperaccumulator plants. Speciation was analysed chromatographically (HPLC-(ICP-MS)-(ESI-MS)) in whole-plant extracts and by tissue-resolution confocal X-ray absorption spectroscopy (µ XANES) in intact shock-frozen hydrated leaves, which were also used for analysing cellular element distribution through X-ray fluorescence (µ XRF). Chromatography revealed up to 20 As-containing species binding &gt;60% of accumulated As. Of these, eight were identified as thiol-bound (phytochelatins; PCs, glutathione; GSH and cystein) species including three newly identified complexes: Cys-As(III)-PC2, Cys-As-(GS)2 and GS-As(III)-desgly-PC2 complex. Confocal µ XANES showed As(V), As(III), As-(GS)3 and As-PCs with varying ratios in various tissues. The epidermis of mature leaves contained the highest proportion of thiol- (mostly PC-) bound As, while in younger leaves a lower proportion of As was thiol-bound. At higher As concentrations, the percentage of unbound As(III) increased in the vein and mesophyll of young mature leaves. At the same time, µ XRF showed an increase of total As in the vein and mesophyll but not in the epidermis of young mature leaves while it was reverse for Zn distribution. Thus, As toxicity was correlated with a change in As distribution pattern and As species, rather than general increase in many tissues.",
Arsenic,2279419,"Detection of Arsenic(III) through Pulsed Laser-Induced Desorption/Ionization of Gold Nanoparticles on Cellulose Membranes Abstract: We have developed an assay based on gold nanoparticle-modified mixed cellulose ester membrane (Au NPs-MCEM) coupled with laser-induced desorption/ionization mass spectrometry (LDI-MS)-for the detection of arsenic(III) ions (arsenite, AsO2(-)) in aqueous solution. When the Au NPs reacted with lead ions (Pb(2+)) in alkaline solution (5 mM glycine-NaOH, pH 12), Au-Pb complexes, PbO, and Pb(OH) were formed immediately on the Au NP surfaces. The Pb species reacted rapidly with subsequently added AsO2(-) to form PbOAs2O3, (PbO)2As2O3, and/or (PbO)3As2O3 shells (2-5 nm) on the Au NPs' surfaces. As a result, significant observable aggregation of the Au NPs occurred in the solution. This Pb(2+)/Au NP probe allowed the detection of AsO2(-) at concentrations as low as 0.6 ?M with high selectivity (at least 100-fold over other anions and metal ions). To further improve the sensitivity, we prepared Au NPs-MCEM for the LDI-MS-based detection of AsO2(-) ions. The intensity of the signal for the [Pb](+) ions in the mass spectra increased when the Au NPs-MCEM reacted with AsO2(-); in contrast, the intensity of the signal for [Au](+) ions decreased. Accordingly, the [Pb](+)/[Au](+) peak ratio increased upon increasing the AsO2(-) concentration over the range from 10 nM to 10 ?M. The limit of detection at a signal-to-noise ratio of 3 was 2.5 nM, far below the action level of As (133 nM, ca. 10 ppb) permitted by the US EPA for drinking water. Relative to other nanoparticle-based arsenic sensors, this approach is rapid, specific, and sensitive; in addition, it can be applied to the detection of AsO2(-) in natural water samples (in this case, streamwater, lake water, tap water, groundwater, and mineral water).",
Arsenic,1350961,"Atomic absorption spectrometry in determination of arsenic, antimony and selenium in environmental samples Abstract: ",
Arsenic,628422,"Induction of apoptosis and inhibition of human gastric cancer MGC-803 cell growth by arsenic trioxide Abstract: Arsenic trioxide (As2O3), used to treat human diseases for centuries in traditional Chinese medicine, has been identified as a very effective antileukaemic agent, but its effect on solid tumours which could be more suitable for clinical treatment with arsenic compounds is still unknown. In this study, we investigated the in vitro effect of As2O3 at concentrations of 0.01-1 microM against six human malignant cell lines, MGC-803, HIC, MCF-7, HeLa, BEL-7402 and A549 cells. As2O3 inhibited growth and induced apoptosis in these malignant cells at varying degrees, in a time dose-dependent manner. The most marked effects were seen in the gastric cancer cell line, MGC-803. In contrast, minimal growth inhibition and induction of apoptosis occurred in human embryonic pulmonary cells following treatment with As2O3 found at the same concentrations. Changes in intracellular Ca2+, following As2O3 treatment were measured by Ca2+ sensitive fluorescent probe Indo-1/AM in flow cytometric assays. The increase in intracellular Ca2+ correlated with the sensitivity of these cells to As2O3, possibly indicating that a critical intracellular Ca2+ signal transduction pathway could be involved in As2O3-mediated cell-death and its selectivity. The marked sensitivity of MGC-803 cells in vitro suggests that As2O3 may be a potential antigastric cancer agent.",
Arsenic,2088483,"Redox signaling mediates the expression of a sulfate-deprivation-inducible microRNA395 in Arabidopsis Abstract: MicroRNA395 (miR395) is a conserved miRNA that targets a low-affinity sulfate transporter (AST68) and three ATP sulfurylases (APS1, APS3 and APS4) in higher plants. In this study, At2g28780 was confirmed as another target of miR395 in Arabidopsis. Interestingly, several dicots contained genes homologous to At2g28780 and a cognate miR395 complementary site but possess a gradient of mismatches at the target site. It is well-established that miR395 is induced during S deprivation in Arabidopsis; however, the signaling pathways that mediate this regulation are unknown. Several findings in the present study demonstrate that redox signaling plays an important role in induction of miR395 during S deprivation. These include the following results: (1) GSH supplementation suppressed miR395 induction in S-deprived plants; (2) miR395 is induced in Arabidopsis seedlings exposed to Arsenate or Cu(2+) , which induces oxidative stress; (3), S deprivation induced oxidative stress, and (4) compromised induction of miR395 during S deprivation in cad2 mutants (deficient in GSH biosynthesis) that is defective in glutaredoxin-dependent redox signaling and ntra/ntrb (defective in thioredoxin reductases a and b) double mutants that are defective in thioredoxin-dependent redox signaling. Collectively, these findings strongly support the involvement of redox signaling in inducing the expression of miR395 during S deprivation in Arabidopsis.",
Arsenic,2343568,"Heavy Metals Toxicity and Bioaccumulation Patterns in the Body Organs of Four Fresh Water Fish Species Abstract: Various environmental pollutants, including metals can cause toxicological effects on aquatic animals especially fish species. Laboratory experiments were conducted to determine acute toxicity and bioaccumulation patterns of arsenic (As), nickel (Ni) and zinc (Zn) in 150-day old fish species (Labeo rohita, Cirrhina mrigala, Catla catla and Ctenopharyngodon idella), separately, in glass aquaria under constant water temperature (30 degrees C), total hardness (300 mg L-1) and pH (7.5). Catla catla showed significantly (P&lt;0.05) highest sensitivity to metals while L. rohita was least sensitive. Significantly variable accumulation of metals was observed in fish that followed the order: Zn&gt;Ni&gt;As. Among exposed fish species, Cirrhina mrigala exhibited significantly higher ability to amass Ni (146.8 +/- 149.1 mu g g(-1)) and Zn (243.0 +/- 190.5 mu g g-1), followed by Ctenopharyngodon idella, Labeo rohita and Catla catla at 96-h LC50. Liver showed higher tendency to accumulate Ni, followed by gills and kidney with significant differences while kidney showed higher tendency to accumulate As, followed by liver. Fins and scales exhibited significantly (P&lt;0.05) least tendency to accumulate all the three metals. Accumulation of metals in different fish species is the function of their membrane permeability, which is highly species specific. Due to this reason different fish species showed different amount of metal accumulated in their bodies. This study also reveals that the metals, being conservative in nature have higher ability of biomagnifications. (C) 2014 PVJ. All rights reserved",
Arsenic,1251016,"Development and survival of Orius insidiosus (Say) nymphs on encapsulated bee pollen-based diet in a Tier-I toxicity assay Abstract: The insidious flower bug, Orius insidiosus (Say) (Heteroptera: Anthocoridae) is an important surrogate species for assessing potential effects of plant-incorporated protectants (PIPs) on nontarget heterotrophic predators. In this study, a continuous dietary exposure system was optimized by assessing the effect of diet composition and age on the survival and development of nymphs of O. insidiosus. Greater than 85% control survival and an acceptable rate of development from nymph hatching to adult was achieved using 5-d-old nymphs at test initiation and a bee pollen-based diet supplemented with 25% Ephestia eggs. There was an unacceptable level of mortality (&gt;40%) and/or a significantly prolonged development time when nymphs were &lt;5 d old at test initiation. When 5-d-old nymphs were fed a bee pollen diet containing 25% Ephestia eggs and 100 ?g/g potassium arsenate, time-dependent mortality was observed with a median lethal time (LT50) of 4.4 d and 100% mortality was observed after 10 d of feeding, indicating the effectiveness of the test system to detect adverse effects by dietary exposure. It is recommended that well-defined 5-d-old nymphs and an encapsulated bee pollen-based diet containing 25% ground Ephestia eggs be used in a Tier-I dietary feeding exposure assay for detecting potential effects of PIPs on O. insidiosus nymphs.",
Arsenic,1350715,"Application and Relevance of Biosensors in The Tanning Industry Abstract: The tanning industry has for a long time been associated as the primal source of pollution to various ecosystems wherever they are sited. Effluent spewed by these leather industries including particulate matter has remained very complex requiring more advanced techniques to examine. One such avenue is the use of ecotoxicological diagnosis of the tanning sector to comprehend the underlying environmental impact. Thus recent advances in biotechnology brought to the fore the relevancy and appropriateness of biosensors in determining pollution load and associated impact to the atmospheric, terrestrial and aquatic ecosystems. Indeed other investigations on Lead, Arsenic and complex anthropogenic and xenobiotics have spurred the development of specific genetically modified organism to facilitate in such investigation. Thus in this paper review the relevancy and advances of the application of biosensors is addressed for purposes of recording, some of the achievements so far attained towards the tanning industry are discussed. However it should be realized that the application of biosensors in evaluating tanning industry effluent is very recent but very opportune area that requires an in-depth ecotoxicological diagnosis through of established biotechnological advances.",
Arsenic,1579315,"Arsenic and other trace elements in two catfish species from Paranaguá Estuarine Complex, Paraná, Brazil Abstract: Concentrations of arsenic and four additional trace elements (Cu, Cr, Ni, and Zn) were determined by inductively coupled plasma-optical emission spectrometry in the muscular tissue of the yellow catfish (Cathorops spixii) and the urutu catfish (Genidens genidens) from Paranaguá Estuarine Complex, Brazil (PEC). The PEC can be characterized by an environment of high ecological and economic importance in which preserved areas of rainforest and mangroves coexist with urban activities as ports and industries. The average concentrations (in milligram per kilogram dry weight) of elements in the muscle tissue of C. spixii are as follows: Zn (31), As (17), Cu (1.17), Cr (0.62), and Ni (0.28). Similar concentrations could be found in G. genidens with exception of As: Zn (36), As (4.78), Cu (1.14), Cr (0.51), and Ni (0.14). Fish from the geographic northern rural region (Guaraqueçaba-Benito) display higher As concentrations in the muscle tissues than fish found in the south-western (urban) part of the PEC. An international comparison of muscle tissue concentrations of trace elements in fish was made. Except for Ni in C. spixii, a tendency of decrease in element concentration with increasing size (age) of the fish could be observed. According to the National Health Surveillance Agency of Brazil, levels of Cr and As exceeded the permissible limits for seafood. An estimation of the provisional tolerable weekly intake of As was calculated with 109 % for C. spixii and with 29 % for G. genidens.",
Arsenic,1337776,"Complete genome sequence and metabolic potential of the quinaldine-degrading bacterium Arthrobacter sp. Rue61a Abstract: ABSTRACT: BACKGROUND: Bacteria of the genus Arthrobacter are ubiquitous in soil environments and can be considered as true survivalists. Arthrobacter sp. strain Rue61a is an isolate from sewage sludge able to utilize quinaldine (2-methylquinoline) as sole carbon and energy source. The genome provides insight into the molecular basis of the versatility and robustness of this environmental Arthrobacter strain. RESULTS: The genome of Arthrobacter sp. Rue61a consists of a single circular chromosome of 4,736,495 bp with an average G + C content of 62.32%, the circular 231,551-bp plasmid pARUE232, and the linear 112,992-bp plasmid pARUE113 that was already published. Plasmid pARUE232 is proposed to contribute to the resistance of Arthrobacter sp. Rue61a to arsenate and Pb2+, whereas the linear plasmid confers the ability to convert quinaldine to anthranilate. Remarkably, degradation of anthranilate exclusively proceeds via a CoA-thioester pathway. Apart from quinaldine utilization, strain Rue61a has a limited set of aromatic degradation pathways, enabling the utilization of 4-hydroxy-substituted aromatic carboxylic acids, which are characteristic products of lignin depolymerization, via ortho cleavage of protocatechuate. However, 4-hydroxyphenylacetate degradation likely proceeds via meta cleavage of homoprotocatechuate. The genome of strain Rue61a contains numerous genes associated with osmoprotection, and a high number of genes coding for transporters. It encodes a broad spectrum of enzymes for the uptake and utilization of various sugars and organic nitrogen compounds. A. aurescens TC-1 is the closest sequenced relative of strain Rue61a. CONCLUSIONS: The genome of Arthrobacter sp. Rue61a reflects the saprophytic lifestyle and nutritional versatility of the organism and a strong adaptive potential to environmental stress. The circular plasmid pARUE232 and the linear plasmid pARUE113 contribute to heavy metal resistance and to the ability to degrade quinaldine, respectively.",
Arsenic,1677385,"Effect of dissolved CO2 on a shallow groundwater system: a controlled release field experiment Abstract: Capturing carbon dioxide (CO(2)) emissions from industrial sources and injecting the emissions deep underground in geologic formations is one method being considered to control CO(2) concentrations in the atmosphere. Sequestering CO(2) underground has its own set of environmental risks, including the potential migration of CO(2) out of the storage reservoir and resulting acidification and release of trace constituents in shallow groundwater. A field study involving the controlled release of groundwater containing dissolved CO(2) was initiated to investigate potential groundwater impacts. Dissolution of CO(2) in the groundwater resulted in a sustained and easily detected decrease of ~3 pH units. Several trace constituents, including As and Pb, remained below their respective detections limits and/or at background levels. Other constituents (Ba, Ca, Cr, Sr, Mg, Mn, and Fe) displayed a pulse response, consisting of an initial increase in concentration followed by either a return to background levels or slightly greater than background. This suggests a fast-release mechanism (desorption, exchange, and/or fast dissolution of small finite amounts of metals) concomitant in some cases with a slower release potentially involving different solid phases or mechanisms. Inorganic constituents regulated by the U.S. Environmental Protection Agency remained below their respective maximum contaminant levels throughout the experiment.",
Arsenic,1351914,"Assessment of cytotoxicity by impedance spectroscopy Abstract: This paper describes a simple and convenient method to monitor on-line cell adhesion by electrical impedance measurements. Immortalized mouse fibroblasts, BALB/3T3, were cultured onto interdigitated electrode structures integrated into the bottom of an in-house fabricated device. Impedance modulus, phase, real and imaginary parts were considered separately and plotted as function of frequency and time to better understand and select the component giving more information on cell adhesion changes. For cytotoxicity assessment, the cells were treated with different concentrations of sodium arsenite used as model toxicant and their responses were monitored on-line. The half inhibition concentration, the required concentration to achieve 50% inhibition, derived from the measurements fall between the results obtained using standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test and colony forming efficiency assay confirming the good sensitivity of the system. In term of impedance signal, the modulus results was found to be the most sensitive of the considered components for cytotoxicity testing of chemicals.",
Arsenic,500225,"Multiple metals predict prolactin and thyrotropin (TSH) levels in men Abstract: Exposure to a number of metals can affect neuroendocrine and thyroid signaling, which can result in adverse effects on development, behavior, metabolism, reproduction, and other functions. The present study assessed the relationship between metal concentrations in blood and serum prolactin (PRL) and thyrotropin (TSH) levels, markers of dopaminergic, and thyroid function, respectively, among men participating in a study of environmental influences on male reproductive health. Blood samples from 219 men were analyzed for concentrations of 11 metals and serum levels of PRL and TSH. In multiple linear regression models adjusted for age, BMI and smoking, PRL was inversely associated with arsenic, cadmium, copper, lead, manganese, molybdenum, and zinc, but positively associated with chromium. Several of these associations (Cd, Pb, Mo) are consistent with limited studies in humans or animals, and a number of the relationships (Cr, Cu, Pb, Mo) remained when additionally considering multiple metals in the model. Lead and copper were associated with non-monotonic decrease in TSH, while arsenic was associated with a dose-dependent increase in TSH. For arsenic these findings were consistent with recent experimental studies where arsenic inhibited enzymes involved in thyroid hormone synthesis and signaling. More research is needed for a better understanding of the role of metals in neuroendocrine and thyroid function and related health implications. (C) 2009 Elsevier Inc. All rights reserved.",
Arsenic,2345851,"Colorimetric Detection of Trace Arsenic(III) in Aqueous Solution Using Arsenic Aptamer and Gold Nanoparticles Abstract: In this study, trace arsenic(iii) (As-III) in aqueous solution was detected by applying a classical aptamer-based gold nanoparticles colorimetric sensing strategy. An arsenic aptamer was used as a sensing probe and gold nanoparticles as a colorimetric indicator. In the absence of As-III, the gold nanoparticles were stabilised by the arsenic aptamer and remained dispersed at high NaCl concentrations, displaying a red solution. Contrarily, in the presence of As-III, the gold nanoparticles were prone to aggregation, owing to the formation of aptamer-As-III complex between the arsenic aptamer and As-III, and thus exhibited a blue solution. By monitoring the colour change, a simple and fast colorimetric assay for As-III was established with a detection range of 1.26-200 ppb and a detection limit of 1.26 ppb. Because this colorimetric assay only involves common reagents and can be assessed visually, it holds great potential for arsenic(iii) monitoring in environment-related and other applications.",
Arsenic,1030231,Multiple malignant and benign epidermal and dermal tumours following arsenic Abstract: ,
Arsenic,1244048,"The palaeosol model of arsenic pollution of groundwater tested along a 32 km traverse across West Bengal, India Abstract: The distribution of As-pollution in groundwater of the deltaic aquifers of south-eastern Asia may be controlled by the subsurface distribution of palaeo-channel sediments (As-polluted groundwaters) and palaeo-interfluvial sediments (As-free groundwaters). To test this idea, termed the palaeosol model of As-pollution, we drilled 10 sites, analysed groundwater from 249 shallow wells (screened &lt;107mbgl), field-tested another 149 for As, and used colour as a guide to the presence or absence of As-pollution in a further 531 wells. Our work was conducted along a 32-km traverse running W to E across southern West Bengal, India. At seven drill sites we logged a palaeo-interfluvial sequence, which occurs as three distinct units that together occupy 20km of the traverse. These palaeo-interfluvial sequences yield As-free groundwaters from brown sands at depth&lt;100m. The palaeo-interfluvial sequences are separated by two deep palaeo-channels, which were logged at 3 sites. The palaeo-channel deposits host As-polluted groundwater in grey sands. Our findings confirm the predictions of the palaeosol model of As-pollution. We show again that well-colour can be used both to successfully predict the degree of As-pollution in groundwater, and to locate regions of buried palaeo-interfluve that will yield As-free groundwater for the foreseeable future.",
Arsenic,1030039,"p53 regulates Hsp90beta during arsenite-induced cytotoxicity in glutathione-deficient cells Abstract: p53, a tumor suppressor and transcription factor, is a critical modulator in the cellular response to stress. Exposure of glutathione-deficient GCS-2 cells to arsenite significantly phosphorylated and stabilized p53. In addition, p53 transcriptionally repressed Hsp90beta gene expression. Mutation analysis revealed a p53 binding site in the 5' flanking region responsible for the regulation of Hsp90beta gene. Electrophoretic mobility shift assay showed that p53 is bound to Hsp90beta promoter region. ATM kinase, a major determinant in the modulation of p53 specifically affected its phosphorylation at Ser-15. ATM kinase-mediated phosphorylation of p53 is regulated through phosphorylation of Chk2. Down-regulation of ATM and Chk2 by their small interfering RNAs (siRNAs) attenuated the arsenite-induced phosphorylation of p53 and restored Hsp90beta mRNA levels. Taken together, these findings suggest that arsenite acts through ATM and Chk2 to induce phosphorylation of p53. This results in the transcriptional repression of Hsp90beta, under GSH-deficient conditions which may play a role in arsenic-mediated pathogenesis.",
Arsenic,1070463,"Prenatal Arsenic Exposure and DNA Methylation in Maternal and Umbilical Cord Blood Leukocytes Abstract: Background: Arsenic is an epigenetic toxicant and could influence fetal developmental programming. Objectives: To evaluate the association between arsenic exposure and DNA methylation in maternal and umbilical cord leukocytes. Methods: Drinking water and urine samples were collected when women were ?28 weeks gestational age and analyzed for arsenic using inductively coupled plasma mass spectrometry. DNA methylation at CpG sites in p16 (n = 7) and p53 (n = 4), and in LINE-1 and Alu repetitive elements (3 CpG sites in each), was quantified using pyrosequencing in 113 pairs of maternal and umbilical blood samples. General linear models evaluated the relationship between DNA methylation and tertiles of arsenic exposure. Results: Mean drinking water arsenic concentration was 14.8 µg/L (Standard deviation: 36.2 µg/L; Range: &lt;1 - 230 µg/L). Methylation in LINE-1 increased by 1.36% (95% confidence interval (CI): 0.52 - 2.21%) and 1.08% (95% CI: 0.07 - 2.10%) in umbilical cord and maternal leukocytes, respectively, in association with the highest versus lowest tertile of total urinary arsenic/gram creatinine. Arsenic exposure was also associated with higher methylation of some of the tested CpG sites in the promoter region of p16 in umbilical cord and maternal leukocytes. No associations were observed for Alu or p53 methylation. Conclusions: Exposure to higher levels of arsenic was positively associated with DNA methylation in LINE-1 repeated elements, and to a lesser degree at CpG sites within the promoter region of the tumor suppressor gene p16. Associations were observed in both maternal and fetal leukocytes. Future research is needed to confirm these results and determine if these small increases in methylation are associated with any health effects.",
Arsenic,1026391,"Arsenic inhibits neurofilament transport and induces perikaryal accumulation of phosphorylated neurofilaments: roles of JNK and GSK-3beta Abstract: The environmental neurotoxin arsenic has recently been associated with altered neurofilament (NF) content in sciatic nerve. We examined herein the impact of sodium arsenite (the inorganic form of arsenic) on NF dynamics. Treatment of differentiated NB2/d1 cells and cultured dorsal root ganglion neurons decreased NF transport into axonal neurites and increased perikaryal phospho-NF immunoreactivity. Both of these effects were prevented by a pharmacological inhibitor (SP600125) of c-jun terminal kinase and by expression of a dominant-negative form of this kinase. Arsenic-induced inhibition of NF transport was prevented by treatment with lithium, a selective inhibitor of glycogen synthase kinase-3beta. Pharmacological inhibitors of cyclin-dependent kinase 5 and p38 mitogen-activated protein kinase did not attenuate the effects of arsenic on NF dynamics. These latter findings suggest that this environmental neurotoxin could contribute to peripheral neuropathy by perturbing NF dynamics.",
Arsenic,1252434,"Arsenic-copper interaction in the kidney of the rat: Influence of arsenic metabolites Abstract: The present study was an attempt to investigate whether the renal accumulation of Cu observed in the kidneys of rats and guinea-pigs exposed to arsenite (As-III) was an effect of arsenite alone or also shared by its metabolites arsenate (As-V), dimethylarsinic acid and monomethylarsonic acid. The four arsenic compounds were administered subcutaneously and separately to rats for 12 days in increasing doses. Kidney, liver and blood were taken and analysed for As, Cu and other trace elements by atomic emission spectrometry. Results indicate that administration of As-V leads to renal Cu accumulation similar to that observed on administration of As-III and that the accumulation in both cases is dependent on the dose of arsenic, although higher doses of As-V were required to achieve renal Cu levels comparable to that of As-III. A constant molar As:Cu ratio independent of arsenic dose was obtained in the kidney. Dimethylarsinic acid did not affect renal Cu levels at all. Administration of monomethylarsonic acid led to a slight increase in renal Cu levels which did not increase further in spite of increased doses of monomethylarsonic acid. It is concluded from these studies that neither the metabolic transformation of inorganic arsenic to its methylated products nor its metabolites (dimethylarsinic acid and monomethylarsonic acid) caused the observed renal Cu accumulation, rather, the inorganic form of As, either in the trivalent or pentavalent form is responsible.",
Arsenic,1352863,Suberoylanilide hydroxamic acid (SAHA) inhibits EGF-induced cell transformation via reduction of cyclin D1 mRNA stability Abstract: ,
Arsenic,1579260,"An evaluation of Bera Lake (Malaysia) sediment contamination using sediment quality guidelines Abstract: Bera Lake is known as the first RAMSAR site and is the largest natural lake in Malaysia. Sediment quality guidelines (SQGs) and Geoaccumulation index were used to evaluate Bera Lake sediment contamination. Five undisturbed cores were collected from Bera Lake sediment. Major and trace levels of elements were determined for 132 subsamples using an inductively coupled plasma mass spectrometry (ICP-MS). The results marked two major groups of metallic elements bonded to the terrestrial and organic-rich sediments. Terrestrial sediments were strongly associated with accumulation of Li, Al, Pb, Cu, Cr, Na, Mg, Sr, and K during main fluxes of metals. However, a strong positive correlation was obtained between Fe, Mn, As, Zn, Cu, Ni, Ca, and Cd elements and TOC and TN. The Mn/Fe ratio revealed a long-term redox and acidic condition at Bera Lake. Geoaccumulation index for all individual metals has classified Bera Lake sediment as low to moderately polluted. However, elemental values when compared with thresholds limits of SQG indicated that Bera Lake sediments were contaminated by arsenic and iron. Results prove that deforestation during the five phases of land developments since 1972 has significantly contributed to the existence of metals fluxes into the area.",
Arsenic,2149170,"Assessment of metal concentrations in commercially important fish species in Black Sea Abstract: In the present study, concentrations of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were measured in the muscle, gill, and gonads of the pelagic fish species Trachurus mediterraneus, Engraulis encrasicolus ponticus, and Sprattus sprattus that are important both commercially and for the ecosystems in the Black Sea. The samples were collected during 2011. The metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) following an acid digestion. The highest concentrations of As, Cd, Co, Cr, Cu, Pb, and Zn were found in E. encrasicolus ponticus, whereas the greatest concentrations of Ni were found in T. mediterraneus and Mn in S. sprattus. Results showed that average metal concentrations in the tissues of T. mediterraneus, E. encrasicolus ponticus, and S. sprattus decreased in the order gill &gt; gonad &gt; muscle, gonad &gt; gill &gt; muscle, and gill &gt; gonad &gt; muscle, respectively, for the three species. When metal concentrations of fish tissues were compared between fish gender, there were only statistical differences in the gonads of the studied fish species (p &lt; 0.05). The present study demonstrated that the metals have different correlations with condition factor (CF) and gonadosomatic index (GSI) of the fish species. Cr showed statistically important positive correlation to the GSI in male T. mediterraneus. Co showed statistically important positive correlation to CF in female E. encrasicolus ponticus, and also Co and Cd showed correlation to CF in male T. mediterraneus. Cd concentrations in the muscle tissues of the fish species were above the maximum acceptable concentration for human consumption.",
Arsenic,1936125,The prokaryotic Mo/W-bisPGD enzymes family: A catalytic workhorse in bioenergetic Abstract: ,
Arsenic,1034465,"Age-dependent metabolic changes in cultured human fibroblasts Abstract: The effects of metabolic poisons on the ATP content of cultured human skin fibroblasts at selected in vitro and in vivo ages were studied. Potassium cyanide, iodacetamide, and Arsenate were used to inhibit ATP restoration by glycolysis and oxidative phosphorylation. Cells treated with these metabolic poisons showed an age-dependent change in their ATP content. The decrease in cellular ATP content after exposure to these drugs was taken as an estimate of ATP turnover. It was found that there was a decrease in the ATP turnover with increasing population doubling level (i.e. in vitro age), and cells cultured from a 68-yr-old donor had a lower ATP turnover than those cultured from a neonatal donor. This decreased ATP turnover correlates with a previous finding of a decreased ability of &quot;older&quot; cells to be stimulated to migrate in culture and suggests that there is a metabolic component to this age-related functional deficiency.",
Arsenic,627265,"Sodium arsenite enhances the cytotoxicity, clastogenicity, and 6-thioguanine-resistant mutagenicity of ultraviolet light in Chinese hamster ovary cells Abstract: Cytotoxicity, chromosome aberrations, and mutations to 6-thioguanine resistance were synergistically increased by incubating the ultraviolet light (UV)-irradiated Chinese hamster ovary (CHO) cells in medium containing sodium arsenite. However, the frequencies of sister-chromatid exchanges and mutations to ouabain resistance induced by UV were not synergistically increased by sodium arsenite. The synergistic effect of sodium arsenite on UV-induced chromosome aberrations varied with cell-harvesting time and decreased with increasing time intervals between UV and sodium arsenite treatments.",
Arsenic,1028730,"Analysis of nickel refinery dusts Abstract: After characterization of bulk samples by inductively coupled plasma emission spectroscopic (ICP-ES) quantitative analysis and X-ray powder diffraction studies, single particle techniques using quantitative image analysis, scanning electron microscopy--energy dispersive analysis by X-ray, and finally laser beam ionization mass spectrometry analysis (LIMA) for surface analysis have been applied to historical nickel refinery dust samples from the nickel refining plant at Clydach in Wales. There were two historical samples of processed material from 1920 and 1929. These samples had a remarkably small particle size range, mean 3 microns and range, 0.75-24 microns. The most significant difference in elemental composition was the presence of 10% arsenic in the 1920 sample compared with 1% in the 1929 sample. The X-ray spectra revealed the presence of NiO in both. However, surprisingly, CuO was identified only in the 1929 sample. Of particular interest was the presence of a component, in the 1920 sample only, identified as the mineral orcelite, a copper-iron-nickel-arsenide-sulphide mineral, predominantly, Ni5-XAs2. Using the LIMA technique, it was found that in both samples, arsenic and arsenic derivative peaks are prominent, indicating the surface availability of arsenic compounds.",
Arsenic,628445,"Decrements in lung function related to arsenic in drinking water in West Bengal, India Abstract: During 1998-2000, the authors investigated relations between lung function, respiratory symptoms, and arsenic in drinking water among 287 study participants, including 132 with arsenic-caused skin lesions, in West Bengal, India. The source population involved 7,683 participants who had been surveyed for arsenic-related skin lesions in 1995-1996. Respiratory symptoms were increased among men with arsenic-caused skin lesions (versus those without lesions), particularly ""shortness of breath at night"" (odds ratio (OR) = 2.8, 95% confidence interval (CI): 1.1, 7.6) and ""morning cough"" (OR = 2.8, 95% CI: 1.2, 6.6) in smokers and ""shortness of breath ever"" (OR = 3.8, 95% CI: 0.7, 20.6) in nonsmokers. Among men with skin lesions, the average adjusted forced expiratory volume in 1 second (FEV1) was reduced by 256.2 ml (95% CI: 113.9, 398.4; p < 0.001) and the average adjusted forced vital capacity (FVC) was reduced by 287.8 ml (95% CI: 134.9, 440.8; p < 0.001). In men, a 100-microg/liter increase in arsenic level was associated with a 45.0-ml decrease (95% CI: 6.2, 83.9) in FEV1 (p = 0.02) and a 41.4-ml decrease (95% CI: -0.7, 83.5) in FVC (p = 0.054). Women had lower risks than men of developing skin lesions and showed little evidence of respiratory effects. In this study, consumption of arsenic-contaminated water was associated with respiratory symptoms and reduced lung function in men, especially among those with arsenic-related skin lesions.",
Arsenic,1018743,"Controlling for time-since-hire in occupational studies using internal comparisons and cumulative exposure Abstract: Employees within an occupational cohort may demonstrate a more favorable mortality experience while maintaining employment than those who leave employment. At the same time, they may experience an apparent decline in health with time-since-hire. The time-since-hire effect may occur independently of exposure but may nevertheless result in groups categorized by cumulative exposure that are not comparable. Controlling for time-since-hire appears to solve this problem. To quantify the empirical bias in estimates of exposure effect due to confounding from time-since-hire, we analyzed two occupational cohorts using Poisson regression with and without adjustment for time-since-hire or time-since-start-of-follow-up. In a cohort exposed to airborne arsenic, a strong dose-response relation with respiratory cancer mortality had been established. In a cohort exposed to external, penetrating ionizing radiation, a weak and controversial dose-response relation had been reported. The parameter estimates relating exposure to disease from the models that explicitly adjusted for time-since-hire or time-since-start-of-follow-up are within 10% of the estimates from models that did not. It appears, from this empirical analysis of two datasets, that occupational studies may not need to adjust explicitly for such time-related factors as time-since-hire or time-since-start-of-follow-up if these are implicitly controlled through other variables in the model.",
Arsenic,1021860,"Vascular hyperpermeability in response to inflammatory mustard oil is mediated by Rho kinase in mice systemically exposed to arsenic Abstract: The mechanisms underlying vascular dysfunction and cardiovascular disease induced by chronic arsenic exposure are not completely understood. We have previously shown that mice chronically fed sodium arsenite are hypersensitive to the permeability-increasing effects of inflammatory mustard oil. The aim of this study was to investigate whether RhoA/Rho kinase (ROCK)-mediated vascular leakage (hyperpermeability) is induced by mustard oil in mice systemically exposed to arsenic. Animals were orally fed water (control group) or sodium arsenite for 8weeks. We compared the blood pressure and microvessel density of the ears between these two groups. Both control and arsenic groups exhibited a similar mean arterial pressure and microvessel density. Microvessel permeability changes that occurred following mustard oil treatment in the presence of Y-27632, a ROCK inhibitor, were quantified using the Evans blue (EB) technique and vascular labeling with carbon particles. Both the excessive leakiness of EB and the high density of carbon-labeled microvessels upon stimulation with mustard oil in the arsenic-fed mice were reduced by Y-27632 treatment. However, RhoA and ROCK2 expression levels were similar between control and arsenic-fed mice. We further investigated ROCK2 levels and ROCK activity in the ears following mustard oil challenge. ROCK2 levels in mouse ears treated with mustard oil were higher in the arsenic group as compared with the control group. Following mustard oil application, ROCK activity was significantly higher in the arsenic-fed mice compared with the control mice. These findings indicate that increased ROCK2 levels and enhanced ROCK activity are responsible for mustard oil-induced vascular hyperpermeability in arsenic-fed mice.",
Arsenic,1020421,"Sodium arsenite administration via drinking water increases genome-wide and Ha-ras DNA hypomethylation in methyl-deficient C57BL/6J mice Abstract: Arsenic is an established human carcinogen. Deficiencies in available animal models have inhibited a detailed analysis of the mechanism of arsenic induced cancer. This study sought to determine the role of a methyl-deficient diet in combination with sodium arsenite on the genomic methylation status and Ha-ras methylation status of C57BL/6J male mice hepatic DNA. Mice were administered arsenic as sodium arsenite via drinking water at 0, 2.6, 4.3, 9.5 or 14.6 mg sodium arsenite/kg/day. Administration occurred 7 days a week for 130 days. Dose-related effects on the liver were evident in mice administered arsenic and methyl-deficient diets. Most prominent were observations of steatosis and microgranulomas. Sodium arsenite increased genomic hypomethylation in a dose dependent manner and methyl-deficiency and sodium arsenite reduced the frequency of methylation at several cytosine sites within the promoter region of the oncogenic gene, Ha-ras. Methylation changes were prominent in a 500 bp non-CpG island-like region of the Ha-ras promoter and less prominent in a 525 bp CpG island-like region. DNA methylation plays an important role in the physiological expression of many genes including Ha-ras. Significantly reduced methylation at a key regulatory region of Ha-ras in the mouse liver may have relevance to understanding arsenic-induced perturbations in the methylation patterns of cellular growth genes involved in the formation of tumors. These findings highlight the effect of sodium arsenite on inherent methylation processes within the hepatic cell.",1
Arsenic,2343501,"Priority persistent contaminants in people dwelling in critical areas of Campania Region, Italy (SEBIOREC biomonitoring study) Abstract: To investigate if protracted living in degraded environments of the Caserta and Naples provinces (Campania Region, Italy) had an impact on exposure of local people, highly toxic persistent contaminants were measured in blood, blood serum, and human milk of a large number of healthy donors. Sampling was carried out from 2008 to 2009. Blood was collected from over 850 20-64-year old donors; by pooling, 84 blood and 84 serum samples were obtained. Milk was donated by 52 mothers: specimens were pooled into six samples. Polychlorodibenzodioxins (PCDDs), polychlorodibenzofurans (PCDFs), and polychlorobiphenyls (PCBs, dioxin-like (DL) and non-dioxin-like (?6PCBs)), arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) were measured in serum (organic biomarkers) and blood (metals); these chemicals and polybromobiphenyl ethers (?9PBDEs) were analyzed in milk. PCDD+PCDF, DL-PCB, TEQTOT, and ?6PCB concentration ranges (medians) in serum were 6.26-23.1 (12.4), 3.42-31.7 (11.5), 10.0-52.8 (23.9) pgTEQ97/g fat, and 55.5-647 (219) ng/g fat, respectively, while in milk concentration ranges were 5.99-8.77, 4.02-6.15, 10.0-14.2 pgTEQ97/g fat, and 48.7-74.2ng/g fat. Likewise, As, Cd, Hg, and Pb findings in blood spanned 2.34-13.4 (5.83), 0.180-0.930 (0.475), 1.09-7.60 (2.60), 10.2-55.9 (28.8) ?g/L, respectively; only Pb could be measured in milk (2.78-5.99?g/L). ?9PBDE levels in milk samples were 0.965-6.05ng/g fat. Biomarkers' concentrations were found to be compatible with their current values in European countries and in Italy, and consistent with an exposure primarily determined by consumption of commercial food from the large distribution system. Based on relatively higher biomarker values within the hematic biomonitoring database, the following municipalities were flagged as possibly deserving attention for health-oriented interventions: Brusciano and Caivano (As), Giugliano (Hg), Pianura (PCDDs+PCDFs), and Qualiano-Villaricca (As, Hg). The analysis of samples' qualitative variability indicated that biomarker composition was sensitive at municipality level, a feature that can potentially drive interventions for future local risk assessment and/or management measures.",
Arsenic,1579291,"Immunotoxicological effects of inorganic arsenic on gilthead seabream (Sparus aurata L.) Abstract: Arsenic (As) has been associated with multitude of animal and human health problems; however, its impact on host immune system has not been extensively investigated. In fish, there are very few works on the potential risks or problems associated to the presence of arsenic. In the present study we have evaluated the effects of exposure (30 days) to sub-lethal concentrations of arsenic (5?M As2O3) in the teleost fish gilthead seabream (Sparus aurata), with special emphasis in the innate immune response. The arsenic concentration was determined using atomic fluorescence spectrometry (AFS) in liver and muscle of exposed fish showing As accumulation in the liver after 30 days of exposure. The hepatosomatic index was increased at significant extent after 10 days but returned to control values after 30 days of exposure. Histological alterations in the liver were observed including hypertrophy, vacuolization and cell-death processes. Focusing on the immunological response, the humoral immune parameters (seric IgM, complement and peroxidase activities) were no affected to a statistically significant extent. Regarding the cellular innate parameters, head-kidney leucocyte peroxidase, respiratory burst and phagocytic activities were significantly increased after 10 days of exposition compared to the control fish. Overall, As-exposure in the seabream affects the immune system. How this might interfere with fish biology, aquaculture management or human consumers warrants further investigations. This paper describes, for the first time, the immunotoxicological effects of arsenic exposure in the gilthead seabream, which is a species with the largest production in Mediterranean aquaculture.",
Arsenic,1029448,"Transplacental and early life exposure to inorganic arsenic affected development and behavior in offspring rats Abstract: To evaluate the developmental neurotoxicity of arsenic in offspring rats by transplacental and early life exposure to sodium arsenite in drinking water, the pregnant rats or lactating dams, and weaned pups were given free access to drinking water, which contained arsenic at concentrations of 0, 10, 50, 100 mg/L from GD 6 until PND 42. A battery of physical and behavioral tests was applied to evaluate the functional outcome of pups. Pups in arsenic exposed groups weighed less than controls throughout lactation and weaning. Body weight of 10, 50 and 100 mg/L arsenic exposed groups decreased significantly on PND 42, 16 and 12, respectively. Physical development (pinna unfolding, fur appearance, incisor eruption, or eye opening) in pups displayed no significant differences between control and arsenic treated groups. The number of incidences within the 100 mg/L arsenic treated group, in tail hung, auditory startle and visual placing showed significant decrease compared to the control group (p &lt; 0.05). In square water maze test, the trained numbers to finish the trials successfully in 50 and 100 mg/L arsenic exposed groups increased remarkably compared to control group, and there was a dose-related increase (p &lt; 0.01) observed. Taken together, these data show that exposure of inorganic arsenite to pregnant dams and offspring pups at levels up to 100 mg/L in drinking water may affect their learning and memory functions and neuromotor reflex.",
Arsenic,1327134,"Induction of chromatid breaks and tetraploidy in Chinese hamster ovary cells by treatment with sodium arsenite during the G2 phase Abstract: Treatment of Chinese hamster ovary (CHO) cells with sodium arsenite during the G2 phase induced poorly condensed chromosomes and chromatid breaks. The induction of chromatid breaks was confirmed by the appearance of micronucleated cells after arsenite-treated G2 cells were allowed to re-enter interphase. When the duration of the G2 phase was artificially divided into 4 periods, more chromatid breaks were induced by treatment with arsenite during the very early G2 phase (or G2/S boundary). In addition to the induction of chromatid breaks, arsenite treatment also remarkably retarded the re-entry of mitotic cells into interphase. By replating and incubating arsenite-treated G2 cells in drug-free medium, we subsequently observed the appearance of a population of cells whose DNA content was between 4C and 8C, and metaphase cells with near-tetraploid chromosome numbers in the next mitotic division.",
Arsenic,735146,"Arsenic exposure assessment in the New England bladder cancer study Abstract: Ingestion of inorganic arsenic in drinking water at levels higher than 150 ?g/L causes skin, lung, bladder, and other cancers. However, the studies of lower exposures are inconsistent, possibly due to exposure misclassification and small study size, limiting the ability to detect small risks. Our participation in a large case-control study conducted in Maine, New Hampshire, and Vermont provided an opportunity to use innovative approaches to more accurately assess exposure to relatively low levels of drinking water arsenic. We interviewed 1,213 cases and 1,418 population-based controls at home and measured arsenic in the drinking water of study participants. The interview included lifetime residential history with water source(s) (private well/spring, public supply, bottled, etc.) and location of all lifetime residences, as well as questions on other known and suspected risk and confounding factors. Total daily tap water intake was calculated from usual adult intake of tap water, coffee, tea, and other beverages. We estimated arsenic level in drinking water for each year lived in a given home by each participant. The measured level was used to estimate water arsenic at the current home. Arsenic levels at past homes with private wells in New England were estimated either by sampling or by linkage to probability maps generated by one of two multivariate geologically-based models estimating the spatial distribution of arsenic in bedrock or unconsolidated aquifers. Arsenic levels in past homes with public supplies in the study area were estimated from abstracted historical data or by linkage with state data. For past residences outside of the study area, we used EPA, USGS, or state data, depending on type of water supply and data availability. Among the 1,123 controls having estimable levels of household drinking water arsenic for ?80% lifetime years, the mean level was 2.2 ?g/L (sd = 4.9), the median was 0.9 ?g/L (IQR = 0.5-2.2 ?g/L), and the 95%ile was 7.9 ?g/L. The mean cumulative lifetime intake was 80.2 mg (sd = 207), the median intake was 30.7 mg (IQR = 13.1-68.4), and the 95%ile was 287 mg. In this large case-control study of bladder cancer, we were successful in estimating arsenic exposure for at least 80% of lifetime years for 80% of our study population, using several innovative approaches.",
Arsenic,1348375,"Draft Genome Sequence of Halomonas sp Strain KM-1, a Moderately Halophilic Bacterium That Produces the Bioplastic Poly(3-Hydroxybutyrate) Abstract: ",
Arsenic,2088452,"Response of antioxidative enzymes to arsenic-induced phytotoxicity in leaves of a medicinal daisy, Wedelia chinensis Merrill Abstract: <strong>BACKGROUND: </strong>Wedelia chinensis Merrill (Asteraceae) is a medicinally important herb, grown abundantly in soils contaminated with heavy metals, including toxic metalloid arsenic (As). The leaves have immense significance in treatment of various ailments.<br /><br /><strong>OBJECTIVE: </strong>The present study was undertaken to ascertain whether the edible/usable parts experience oxidative stress in the form of membrane damage during As exposure or not.<br /><br /><strong>MATERIALS AND METHODS: </strong>Responses of seven antioxidant enzymes were studied in leaves under 20 mg/L of As treatment in pot experiment.<br /><br /><strong>RESULTS: </strong>When compared to control, activities of superoxide dismutase, monodehydroascorbatereductase, dehydroascorbatereductase, glutathione reductase, and gluathione peroxidase had increased, while the catalase level reduced and ascorbate peroxidase activity changed non-significantly in As-treated seedlings. This suggested overall positive response of antioxidant enzymes to As-induced oxidative stress. Although hydrogen peroxide content increased, level of lipid peroxidation and magnitude of membrane damage was quite normal, leading to normal growth (dry weight of shoot) of plant under Astreatment.<br /><br /><strong>CONCLUSION: </strong>W.chinensis is tolerant of As-toxicity, and thus, can be grown in As-contaminated zones.",
Arsenic,734891,"Identification of arsenic-binding proteins in human cells by affinity chromatography and mass spectrometry Abstract: Exposure to high levels of arsenic can cause a wide range of health effects, including cancers of the bladder, lung, skin, and kidney. However, the mechanism(s) of action underlying these deleterious effects of arsenic remains unclear. Arsenic binding to cellular proteins is a possible mechanism of toxicity, and identifying such binding is analytically challenging because of the large concentration range and variety of proteins. We describe here an affinity selection technique, coupled with mass spectrometry, to select and identify specific arsenic-binding proteins from a large pool of cellular proteins. Controlled experiments using proteins either containing free cysteine(s) or having cysteine blocked showed that the arsenic affinity column specifically captured the proteins containing free cysteine(s) available to bind to arsenic. The technique was able to capture and identify trace amounts of bovine biliverdin reductase B present as a minor impurity in the commercial preparation of carbonic anhydrase II, demonstrating the ability to identify arsenic-binding proteins in the presence of a large excess of non-specific proteins. Application of the technique to the analysis of subcellular fractions of A549 human lung carcinoma cells identified 50 proteins in the nuclear fraction, and 24 proteins in the membrane/organelle fraction that could bind to arsenic, adding to the current list of only a few known arsenic-binding proteins.",1
Arsenic,1015755,"Arsenic, organic foods, and brown rice syrup Abstract: BACKGROUND: Rice can be a major source of inorganic arsenic (Asi) for many sub-populations. Rice products are also used as ingredients in prepared foods, some of which may not be obviously rice-based. Organic brown rice syrup (OBRS) is used as a sweetener in organic food products as an alternative to high fructose corn syrup. We hypothesized that OBRS introduces arsenic into these products. OBJECTIVE: We determined the concentration and speciation of arsenic (As) in commercially available brown rice syrups, and in products containing OBRS including toddler formula, cereal/energy bars, and high energy foods used by endurance athletes. METHODS: We used ICP-MS and IC-ICP-MS to determine total As (Astotal) concentrations and As speciation in products purchased via the internet or in stores in the Hanover, NH area. DISCUSSION: We found that OBRS can contain high concentrations of Asi and dimethylarsenate (DMA). An 'organic' toddler milk formula containing OBRS as the primary ingredient had Astotal concentrations up to six times the EPA safe drinking water limit. Cereal bars and high energy foods containing OBRS also had higher As concentrations than equivalent products that did not contain OBRS. Inorganic As was the main As species in the majority of food products tested in this study. CONCLUSIONS: There are currently no US regulations applicable to As in food, but our findings suggest that the OBRS products we evaluated may introduce significant concentrations of Asi to an individual's diet. Thus, we conclude that there is an urgent need for regulatory limits on As in food.",
Arsenic,1031072,"Arsenic uptake and depuration by red crayfish, Procambarus clarkii, exposed to various concentrations of monosodium methanearsonate (MSMA) herbicide Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM INVERTEBRATE ENVIRONMENTAL TOXICOLOGY WATER POLLUTION FOOD RESIDUE SHELLFISH",
Arsenic,736798,"Synergistic effect of folic acid and vitamin B12 in ameliorating arsenic-induced oxidative damage in pancreatic tissue of rat Abstract: The efficacies of two nutritional factors, folic acid and vitamin B12, were assessed in this study against arsenic-induced islet cellular toxicity. Rats were divided into four groups consisting of five rats in each group: Group A, control; Group B, arsenic-treated; Group C, arsenic+folic acid; and Group D, arsenic+folic acid+vitamin B12. The dose of arsenic, folic acid and vitamin B12, respectively, was 3 mg, 36 microg and 0.63 microg kg(-1) body weight day(-1) for 30 days. Results showed that, compared to control group, there was a significant increase in the levels of nitric oxide (NO), malondialdehyde (MDA) and hydroxyl radical (OH-) formation in the pancreatic tissue of arsenic-treated rats, while the activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), and cellular content of antioxidant glutathione (GSH) were low in these animals. The serum level of tumor necrosis factor-alpha (TNF-alpha) and IL-6 was significantly high in these animals. Light microscopic examination showed a marked fall in the number of islet cells. Concomitant administration of either folic acid or folic acid and vitamin B12 with arsenic significantly restored all these parameters. Although folic acid alone could not restore the normal level of TNF-alpha and IL-6, combined folic acid and vitamin B12 could restore it. Folic acid and vitamin B12 combined also could recover islet cell count. These results suggest that folic acid+vitamin B12 are capable of reducing arsenic-induced cellular oxidative and inflammatory toxic changes. Thus, supplement with vitamin B12+folic acid may be predicted as a possible nutritional management strategy against arsenic-induced toxicity.",
Arsenic,1019530,"When to be skeptical of negative studies: Pitfalls in evaluating occupational risks using population-based case-control studies Abstract: This study investigated arsenic and lung cancer incidence in a community setting in the Montreal area. Job histories and sociodemographic factors were collected by interview from 857 lung cancer cases, 533 general population controls, and 1,360 controls with other cancers. Chemist-hygienists assessed each subject's life-time occupational exposure to 294 substances. Logistic regressions yielded arsenic/lung cancer odds ratios of 1.1 (95% confidence interval = 0.60, 1.7) based on cancer controls, and 0.82 (95% confidence interval = 0.41, 1.6) based on population controls. Risk did not rise with increasing level or probability of exposure. Worksite studies consistently show lung carcinogenicity from arsenic. Since confounding from other chemicals was well controlled, the most likely explanation is substantially lower exposures than in previous studies. The lack of association in this study demonstrates the need for caution in interpreting negative findings from population-based case-control studies, particularly when exposures are low or rare, as well as the difficulty in generating hypotheses from such studies.",
Arsenic,734936,"Increased skin cancer mortality in Chile beyond the effect of ageing: Temporal analysis 1990 to 2005 Abstract: Chile has a medium-to-high skin cancer mortality rate. Previous studies have shown an increasing rate of skin cancer mortality. We evaluated skin cancer mortality characteristics and their temporal evolution in Chile from 1990 to 2005 in a mixed ecological study using death certificate databases. Age, sex, year and region of residence were obtained for melanoma and non-melanoma deaths. Crude and age-sex-adjusted rates were calculated using the national projections and WHO 2000 standard population data. Descriptive and temporal analyses, using a Prais-Winsten regression, were computed. A total of 3588 deaths were registered, of which 55% were melanoma and 54% occurred in men (median age 71 years; women were older). The adjusted rate was 1.75 deaths per 100,000 inhabitants (2.22 in men vs. 1.39 in women). Melanoma skin cancer and non-melanoma skin cancer mortality had a tendency to increase. In conclusion, skin cancer mortality is rising beyond the rate predicted by ageing. An increased incidence due to changes in modifiable factors, such as exposure to ultraviolet radiation and arsenic, might explain the increase in skin cancer mortality.",
Arsenic,1338620,Bioreporters and biosensors for arsenic detection. Biotechnological solutions for a world-wide pollution problem Abstract: A wide variety of whole cell bioreporter and biosensor assays for arsenic detection has been developed over the past decade. The assays permit flexible detection instrumentation while maintaining excellent method of detection limits in the environmentally relevant range of 10-50?g arsenite per L and below. New emerging trends focus on genetic rewiring of reporter cells and/or integration into microdevices for more optimal detection. A number of case studies have shown realistic field applicability of bioreporter assays.,
Arsenic,1347340,"ASNA1, an ATPase targeting tail-anchored proteins, regulates melanoma cell growth and sensitivity to cisplatin and arsenite Abstract: <strong>PURPOSE: </strong>ASNA1 is homologous to E. coli ArsA, a well characterized ATPase involved in efflux of arsenite and antimonite. Cells resistant to arsenite and antimonite are cross-resistant to the chemotherapeutic drug cisplatin. ASNA1 is also an essential ATPase for the insertion of tail-anchored proteins into ER membranes and a novel regulator of insulin secretion. The aim of this study was to determine if altered ASNA1 levels influenced growth and sensitivity to arsenite and cisplatin in human melanoma cells.<br /><br /><strong>METHODS: </strong>Cultured melanoma T289 cells were transfected with plasmids containing sense or antisense ASNA1. Cells were exposed to cisplatin, arsenite and zinc. Cell growth and chemosensitivity were evaluated by the MTT assay and apoptosis by a TUNEL assay.<br /><br /><strong>RESULTS: </strong>ASNA1 expression was necessary for growth. T289 clones with decreased ASNA1 expression exhibited 51 +/- 5% longer doubling times than wildtype T289 (P = 0.0091). After exposure to cisplatin, ASNA1 downregulated cells displayed a significant increase in apoptosis. The cisplatin IC(50) in ASNA1 underexpressing cells was 41.7 +/- 1.8% compared to wildtype (P = 0.00097) and the arsenite IC(50) was 59.9 +/- 3.2% of wildtype IC(50) (P = 0.0067).<br /><br /><strong>CONCLUSIONS: </strong>Reduced ASNA1 expression is associated with significant inhibition of cell growth, increased apoptosis and increased sensitivity to cisplatin and arsenite.",
Arsenic,1031917,"Arsenic exposure in multiple environmental media in children near a smelter Abstract: A nationwide survey of heavy-metal exposure in children living near primary nonferrous metal smelters demonstrated high urine arsenic levels in children living near a copper smelter in Ajo, Arizona. Airborne smelter emissions and drinking water were the apparent sources of exposure. To determine whether increased arsenic absorption had produced adverse health effects, we conducted an evaluation of 132 Ajo children 5 to 18 years old and compared results with those of 47 children from a comparison town with low arsenic exposure. Environmental testing showed that Ajo's municipal water supply contained arsenic in concentrations of 0.09 mg/l (the EPA standard is 0.05 mg/l); arsenic concentrations in dust averaged 342.2 microgram/g. Urine arsenic levels in Ajo children correlated positively with amount of tap-water consumed (r = .32, p less than. 0002) and with distance of residence from the smelter (r = .20, p less than .02). Tap-water drinkers had significantly higher urine arsenic levels than bottled water drinkers (t = 4.21 p less than .001). Mean urine arsenic levels were significantly higher for children in Ajo (4.75 microgram/100 ml) than for children in the comparison town (1.17 microgram/100 ml). Hair arsenic levels correlated poorly with arsenic exposure. Despite the study population's chronic exposure to elevated environmental levels of arsenic, no clinical or hematologic abnormalities attributable to arsenic were found.",
Arsenic,1677521,"Understanding Arsenate Reaction Kinetics with Ferric Hydroxides Abstract: Understanding arsenic reactions with ferric hydroxides is important in understanding arsenic transport in the environment and in designing systems for removing arsenic from potable water. Many experimental studies have shown that the kinetics of arsenic adsorption on ferric hydroxides is biphasic, where a fraction of the arsenic adsorption occurs on a time scale of seconds while full equilibrium may require weeks to attain. This research employed density functional theory modeling in order to understand the mechanisms contributing to biphasic arsenic adsorption kinetics. The reaction energies and activation barriers for three modes of arsenate adsorption to ferric hydroxides were calculated. Reaction energies depended on the net charge of the complexes, which is a function of the system pH value. Physical adsorption of arsenate to ferric hydroxide proceeded with no activation barrier, with reaction energies ranging from -21 to -58 kJ/mol. The highest reaction energies for physical adsorption resulted from negative charge assisted hydrogen bonding between H atoms on the ferric hydroxide and O atoms in arsenate. The conversion of physically adsorbed arsenate into monodentate surface complexes had activation barriers ranging from 62 to 73 kJ/mol, and reaction energies ranging from -23 to -38 kJ/mol. The conversion of monodentate surface complexes to bidentate, binuclear complexes had activation barriers ranging from 79 to 112 kJ/mol, and reaction energies ranging from -11 to -55 kJ/mol. For release of arsenate from uncharged bidentate complexes, activation barriers as high as 167 kJ/mol were encountered. Increasingly negative charges on the complexes lowered the activation barriers for desorption of arsenate, and in complexes with -2 charges, the highest activation barrier was 65 kJ/mol. This study showed that the slow kinetics associated with arsenic adsorption and desorption can be attributed to the high activation energies for forming and breaking bonds with the ferric hydroxide.",
Arsenic,2279502,"Identification and characterization of the arsenite methyltransferase from a protozoan, Tetrahymena pyriformis Abstract: Arsenic (As) methylation in aquatic microbes plays a major role in the biogeochemistry of As. Protozoa, especially the free-living freshwater species, are important players in aquatic ecological health. In this study, an arsenite (As(III)) methyltransferase, TpyArsM, was identified and characterized in a free-living protozoan, Tetrahymena pyriformis. In order to confirm its function, TpyarsM gene was knocked-out in Tetrahymena and was also heterologously expressed in hypersensitive E. coli; these events resulted in expected decreases in As tolerance and methylation ability, respectively. In-vitro tests revealed that purified TpyArsM protein methylated inorganic As to mono- and di- methylarsenate, and also had the novel property of producing trimethylarsenite (TMA(III)) and dimethylarsine (Me2AsH) gases. This new methyltransferase gene, identified in a species near the base of the food web, has enriched our knowledge of As methyltransferases and has great potential for bioremediation of As-contaminated environments.",
Arsenic,1339202,"Glucose starvation-induced dispersal of Pseudomonas aeruginosa biofilms is cAMP and energy dependent Abstract: Carbon starvation has been shown to induce a massive dispersal event in biofilms of the opportunistic pathogen Pseudomonas aeruginosa; however, the molecular pathways controlling this dispersal response remain unknown. We quantified changes in the proteome of P. aeruginosa PAO1 biofilm and planktonic cells during glucose starvation by differential peptide-fingerprint mass-spectrometry (iTRAQ). In addition, we monitored dispersal photometrically, as a decrease in turbidity/opacity of biofilms pre-grown and starved in continuous flow-cells, in order to evaluate treatments (e.g. inhibitors CCCP, arsenate, chloramphenicol, L-serine hydroxamate) and key mutants altered in biofilm development and dispersal (e.g. nirS, vfr, bdlA, rpoS, lasRrhlR, Pf4-bacteriophage and cyaA). In wild-type biofilms, dispersal started within five minutes of glucose starvation, was maximal after 2 h, and up to 60% of the original biomass had dispersed after 24 h of starvation. The changes in protein synthesis were generally not more than two fold and indicated that more than 100 proteins belonging to various classes, including carbon and energy metabolism, stress adaptation, and motility, were differentially expressed. For the different treatments, only the proton-ionophore CCCP or arsenate, an inhibitor of ATP synthesis, prevented dispersal of the biofilms. For the different mutants tested, only cyaA, the synthase of the intracellular second messenger cAMP, failed to disperse; complementation of the cyaA mutation restored the wild-type phenotype. Hence, the pathway for carbon starvation-induced biofilm dispersal in P. aeruginosa PAO1 involves ATP production via direct ATP synthesis and proton-motive force dependent step(s) and is mediated through cAMP, which is likely to control the activity of proteins involved in remodeling biofilm cells in preparation for planktonic survival.",
Arsenic,2278436,"Root porosity, radial oxygen loss and iron plaque on roots of wetland plants in relation to zinc tolerance and accumulation Abstract: Wetland plants have been widely used in constructed wetlands for the clean-up of metal-contaminated waters. This study investigated the relationship between rate of radial oxygen loss (ROL), root porosity, Zn uptake and tolerance, Fe plaque formation in wetland plants. <br> <br>A hydroponic experiment and a pot trial with Zn-contaminated soil were conducted to apply different Zn level treatments to various emergent wetland plants. <br> <br>Significant differences were found between plants in their root porosities, rates of ROL, Zn uptake and Zn tolerance indices in the hydroponic experiment, and concentrations of Fe and Mn on roots and in the rhizosphere in the pot trial. There were significant positive correlations between root porosities, ROL rates, Zn tolerance, Zn, Fe and Mn concentrations on roots and in the rhizosphere. Wetland plants with higher root porosities and ROL tended to have more Fe plaque, higher Zn concentrations on roots and in their rhizospheres, and were more tolerant of Zn toxicity. <br> <br>Our results suggest that ROL and root porosity play very important roles in Fe plaque formation, Zn uptake and tolerance, and are useful criteria for selecting wetland plants for the phytoremediation of Zn-contaminated waters and soils/sediments.",
Arsenic,2279051,"Water-supply options in arsenic-affected regions in Cambodia: Targeting the bottom income quintiles Abstract: In arsenic-affected regions of Cambodia, rural water committees and planners can choose to promote various arsenic-avoidance and/or arsenic-removal water supply systems. Each of these has different costs of providing water, subsequently born by the consumer in order to be sustainable. On a volumetric basis ($/m3-yr) and of the arsenic-avoidance options considered, small-scale public water supply - e.g., treated water provided to a central tap stand - is the most expensive option on a life-cycle cost basis. Rainwater harvesting, protected hand dug wells, and vendor-supplied water are the cheapest with a normalized present worth value, ranging from $2 to $10 per cubic meter per year of water delivered. Subsidization of capital costs is needed to make even these options affordable to the lowest (Q5) quintile. The range of arsenic-removal systems considered here, using adsorptive media, is competitive with large-scale public water supply and deep tube well systems. Both community level and household-scale systems are in a range that is affordable to the Q4 quintile, though more research and field trials are needed. At a target cost of $5.00/m3, arsenic removal systems will compete with the OpEx costs for most of the arsenic-safe water systems that are currently available. The life-cycle cost approach is a valuable method for comparing alternatives and for assessing current water supply practices as these relate to equity and the ability to pay.",
Arsenic,628074,"Arsenic inhibition of the JAK-STAT pathway Abstract: The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway is an essential cascade for mediating normal functions of different cytokines in the development of the hematopoietic and immune systems. Chronic exposure to arsenic has been found to cause immunotoxicity and has been associated with the suppression of hematopoiesis (anemia and leukopenia). Here, we report the novel finding of arsenic-mediated inactivation of the JAK-STAT signaling pathway by its direct interaction with JAK tyrosine kinase. Pretreatment with sodium arsenite strongly inhibited IL-6-inducible STAT3 tyrosine phosphorylation in HepG2 cells and did not affect its serine phosphorylation. As a result, sodium arsenite completely abolished STAT activity-dependent expression of suppressors of cytokine signaling (SOCS). Both cellular and subcelluar experiments showed that the inhibition of JAK-STAT signaling resulted from JAK tyrosine kinase's direct interaction with arsenite, and that arsenic's suppression of JAK tyrosine kinase activity also occurred in the interferon gamma (IFNgamma) pathway. The ligand-independent inhibition by arsenic indicates that JAK was the direct target of arsenic action. Other inflammatory stimulants, stress agents, and metal cadmium failed to induce similar effects on the tyrosine phosphorylation of STAT3 as arsenic does. Our experiments also revealed that arsenic inactivation of the JAK-STAT pathway occurred independent of arsenic activation of MAP kinases. Taken together, our findings indicate that arsenic directly inhibits JAK tyrosine kinase activity and suggest that this direct interference in the JAK-STAT pathway may play a role in arsenic-associated pathogenesis.",
Arsenic,1508590,"Preparation of drinking water used in water supply systems of the towns Zrenjanin and Temerin by electrochemical methods Abstract: The aim of this work was the development and application of the pilot plant with the capacity of 1000 L/day for the purification of groundwater used for human consumption characterized with high concentration of arsenic and increased values of organic pollutants, ammonia, nitrites, color and turbidity. For that purpose, groundwater from the production wells supplying the towns Zrenjanin and Temerin (Vojvodina, Serbia) was used. Due to its complex composition, the purification system required the combination of the electroreduction/electrocoagulation, using iron and aluminum electrode plates with/without ozonation, followed by the electromagnetic treatment and the finally by the simultaneous ozonation/UV treatment. The electroreduction was used for the removal of nitrates, nitrites, and Cr(VI), while the removal of arsenic, heavy metals, suspended solids, color and turbidity required the application of the electrocoagulation with simultaneous ozonation. Organic contaminants and ammonia were removed completely in the last treatment step by applying the simultaneous ozonation/UV treatment. All measured parameters in the purified water were significantly lower compared to the regulated values. Under the optimum treatment conditions, the removal efficiencies for color, turbidity, suspended solids, total arsenic, total chromium, Ni(II), total copper, sulfates, fluorides, chemical oxygen demand, ammonia, nitrates, and nitrites were 100%. The removal efficiencies of the total manganese and iron were 85.19% and 97.44%, respectively, whilst the final concentrations were 4 and 7 ?g/L, respectively.",
Arsenic,1383531,"Gallium Arsenide Selectively Suppresses Antigen Processing by Splenic Macrophages for CD4+ T Cell Activation Abstract: The effect of gallium-arsenide (1303000) on the antigen processing capability of splenic macrophages was studied in mice. C3DF1-mice were injected intraperitoneally with 12.5 or 200mg/kg gallium-arsenide. They were killed 1 or 5 days later and changes in splenic cellularity were determined. The splenic plaque forming cell (PFC) response to sheep red blood cells (SRBCs) was evaluated. The ability of splenic macrophages from mice injected with 200mg/kg gallium-arsenide to induce interleukin-2 production by antigen specific CD4+ helper T-cell hybridomas stimulated with pigeon cytochrome-c, pork insulin, hen egg lysozyme, and chicken ovalbumin was examined. The effects of expression of major histocompatibility complex class-II molecules were evaluated. The ability of T-cells to respond to peptides derived from pigeon cytochrome-c, pork insulin, hen egg lysozyme, and chicken ovalbumin was also evaluated. Gallium-arsenide did not significantly affect splenic weight or cellularity. Gallium-arsenide caused a dose dependent decrease in the PFC response to SRBCs. Gallium-arsenide significantly decreased the responses to pigeon cytochrome-c and pork insulin, but not to hen egg lysozyme and chicken ovalbumin. The effects on pigeon cytochrome-c and pork insulin were more pronounced when measured 5 days than 2 days after gallium-arsenide exposure. Gallium-arsenide did not alter expression of the major histocompatibility class-II molecules or the T-cell responses to the peptides. The authors conclude that gallium-arsenide selectively inhibits the ability of splenic macrophages to process soluble antigens such as pigeon cytochrome-c and pork insulin. Their responses to antigen peptides are not affected. The inhibitory effect on soluble antigen processing is exacerbated by a longer exposure time, which suggests that gallium-arsenide metabolic degradation products may mediate the adverse effects on splenic macrophages.",
Arsenic,2064239,"Arsenoriboside degradation in marine systems: The use of bacteria culture incubation experiments as model systems Abstract: Arsenoribosides (as glycerol; phosphate; sulfate and sulfonate) persisted in all bacteria-inoculated cultures irrespective of the source of bacteria (seawater, macro-algae surface) or the culture media used (DIFCO Marine Broth 2216 or novel blended Hormosira banksii tissue-based). This is unlike observations from traditional macro-algae tissue decomposition studies or in nature. In addition known arsenoriboside degradation products such as dimethylarsenoethanol (DMAE), dimethylarsenate (DMA), methylarsenate (MA) and arsenate - As(V) were not detected in any cultures. Consequently, the use of bacterial culture incubation experiments to explain the fate of arsenoribosides in marine systems appears limited as the processes governing arsenoriboside degradation in these experiments appear to be different to those in macro-algae tissue decomposition studies or in nature.",
Arsenic,8427,Human arsenic exposure in relation to a copper smelter Abstract: ,
Arsenic,1016080,"Comparative study of liver cancer patients in arsenic exposed and non-exposed areas of Pakistan Abstract: The investigated data shows that arsenic (As) in drinking water is associated with increased mortality from different types of cancers including liver cancer. In this study, blood and scalp hair samples of male liver cancer patients and healthy referents belonging to As exposed areas of Sindh Pakistan were analyzed for As contents. The As levels in drinking water of understudy area showed that sections of this population was exposed to 3-15-folds higher concentrations of As than permissible limit. For comparative purposes, blood and scalp hair samples of matched cancerous patient as referent patients belonging to big city (Hyderabad) who have used municipal treated water with low As levels &lt;10 ?g/L were also collected. The results of this study showed that the average As concentration was higher in the blood and scalp hair of exposed and non-exposed referent cancer patients as compared to referents (p?&lt;?001). The exposed cancerous patients have twofolds higher As level in both biological samples as related to non-exposed case matched cancerous male subjects.",
Arsenic,627287,"Arsenic in drinking water and skin cancers: Cell-type specificity (Taiwan, R.O.C.) Abstract: OBJECTIVE: The association between arsenic ingestion and cancer has been documented for more than a century. Previous studies showed that the carcinogenic effects of arsenic on the urinary system are cell-type specific. To evaluate whether this is also true for skin cancers, we conducted an ecological study in 243 townships in Taiwan. METHODS: The arsenic exposure was assessed on the basis of measurement reports from a previous survey, and cases of skin cancer were identified using the information gathered by the National Cancer Registry Program. We analyzed the data by regression models using multiple variables to describe the exposure status, and an urbanization index was also included in the models to adjust for the effects of urbanization. RESULTS: A total of 2369 patients with skin cancer, comprising 1415 men and 954 women, were registered between 1 January 1980 and 31 December 1989. Among the three major cell types of skin cancer, squamous cell carcinoma and basal cell carcinoma appear to be associated with ingestion of arsenic. Such an association was not observed for malignant melanoma. CONCLUSIONS: The results suggested that the carcinogenicity of arsenic on skin is cell-type specific, which is compatible with the findings in previous studies on urinary cancers.",
Arsenic,2149306,EFFECT OF PARBOILING ON AND SEASONAL VARIATIONS THE ARSENIC CONTENT IN THE MARINE BROWN ALGA 'SARGASSUM HORNERI' Abstract: ,
Arsenic,2064297,"Diverse effects of arsenic on selected enzyme activities in soil-plant-microbe interactions Abstract: Under the influence of pollutants, enzyme activities in plant-microbe-soil systems undergo changes of great importance in predicting soil-plant-microbe interactions, regulation of metal and nutrient uptake, and, ultimately, improvement of soil health and fertility. We evaluated the influence of As on soil enzyme activities and the effectiveness of five field crops for As phytoextraction. The initial As concentration in soil was 50mg As kg(-1) soil; planted clean soil, unplanted polluted soil, and unplanted clean soil served as controls. After 10 weeks, the growth of the plants elevated soil dehydrogenase activity relative to polluted but unplanted control soils by 2.4- and 2.5-fold for sorghum and sunflower (respectively), by 3-fold for ryegrass and sudangrass, and by 5.2-fold for spring rape. Soil peroxidase activity increased by 33% with ryegrass and rape, while soil phosphatase activity was directly correlated with residual As (correlation coefficient R(2)=0.7045). We conclude that soil enzyme activities should be taken into account when selecting plants for phytoremediation.",
Arsenic,1034326,"Further studies on chronic arsenical dermatosis Abstract: The prevalence of chronic arsenical dermatosis from drinking tube well is more and more recognized in different villages of West Bengal. A total of 1068 cases have been recorded so far by the School of Tropical Medicina Calcutta, since 1st case diagnosed in July, 1983. 36 villages of 6 districts have been found to be affected so far with the disease. Melanosis (diffuse and spotted) and keratosis (diffuse & punctate in palms, soles and other sites) are the main features of the disease. Cutaneous malignancy was found in 3 out of 1000 cases of chronic arsenical dermatosis. The severity of dermatosis correlated well with concentration of arsenic in the consumed tube well water as well as the duration of arsenic contaminated water consumption. finding of significant concentration of arsenic in nails, hair and skin scales not only confirms the clinical diagnosis but also clinches the diagnosis in doubtfully positive cases and detects the subclinical arsenic toxicity in some of the apparently unaffected members of the affected family.",
Arsenic,628112,"Decreasing trend in renal disease mortality after cessation from arsenic exposure in a previous arseniasis-endemic area in southwestern Taiwan Abstract: Arsenic has been well documented as a major risk factor for blackfoot disease (BFD), a unique peripheral vascular disease that was endemic in the southwestern coast of Taiwan, where residents imbibed artesian well water containing excessive amounts of arsenic for more than 50 yr. Long-term arsenic exposure has also been reported to be associated with mortality attributed to renal disease. A tap-water supply system was implemented in the early 1960s in the BFD endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study was to examine whether mortality attributed to arsenic-induced renal diseases decreased after the improvement of the drinking-water supply system through elimination of arsenic exposure from artesian well water. Standardized mortality ratios (SMRs) for renal diseases were calculated for the BFD endemic area for the years 1971-2000. Results show that mortality from renal disease declined gradually after improvement of the drinking-water supply system to eliminate arsenic from artesian well water. Based on the reversibility criterion, the association between arsenic exposure and mortality attributed to renal disease is likely to be positively correlated.",
Arsenic,2279078,"Roxarsone and its metabolites in chicken manure significantly enhance the uptake of As species by vegetables Abstract: Roxarsone is an organoarsenic feed additive which can be finally degraded to other higher toxic metabolites after excreted by animal. In this work, the uptake of As species by vegetables treated with chicken manure bearing roxarsone and its metabolites was investigated. It was showed that more than 96% of roxarsone added in chicken feed was degraded and converted to arsenite, monomethylarsonic acid, dimethylarsinic acid, arsenate, 4-hydroxyphenylarsonic acid and other unknown As species. Arsenite and arsenate could be found in roots of vegetables but only arsenite transported up to shoots. Chicken manure bearing roxarsone and its metabolites increased 33-175% of arsenite and 28%?seven times of arsenate in vegetable roots, 68-175% of arsenite in edible vegetable shoots. Arsenite, the most toxic As form, was the major extractable As species in vegetables accounted for 79-98%. The results reflected that toxic element As could be absorbed by vegetables via the way: roxarsone in feed?animal?animal manure?soil?crop and the uptake of As species would be enhanced by using chicken manure bearing roxarsone and its metabolites as organic fertilizer.",
Arsenic,1339087,"Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin, Vietnam Abstract: Across West Bengal and Bangladesh, concentrations of Cl in much groundwater exceed the natural, upper limit of 10 mg/L. The Cl/Br mass ratios in groundwaters range up to 2500 and scatter along mixing lines between waste-water and dilute groundwater, with many falling near the mean end-member value for waste-water of 1561 at 126 mg/L Cl. Values of Cl/Br exceed the seawater ratio of 288 in uncommon NO(3)-bearing groundwaters, and in those containing measurable amounts of salt-corrected SO(4) (SO(4) corrected for marine salt). The data show that shallow groundwater tapped by tube-wells in the Bengal Basin has been widely contaminated by waste-water derived from pit latrines, septic tanks, and other methods of sanitary disposal, although reducing conditions in the aquifers have removed most evidence of NO(3) additions from these sources, and much evidence of their additions of SO(4). In groundwaters from wells in palaeo-channel settings, end-member modelling shows that &gt;25% of wells yield water that comprises ?10% of waste-water. In palaeo-interfluvial settings, only wells at the margins of the palaeo-interfluvial sequence contain detectable waste water. Settings are identifiable by well-colour survey, owner information, water composition, and drilling. Values of Cl/Br and faecal coliform counts are both inversely related to concentrations of pollutant As in groundwater, suggesting that waste-water contributions to groundwater in the near-field of septic-tanks and pit-latrines (within 30 m) suppress the mechanism of As-pollution and lessen the prevalence and severity of As pollution. In the far-field of such sources, organic matter in waste-water may increase groundwater pollution by As.",
Arsenic,8475,"Cytogenetic analysis of bone marrow cells and spermatogonia of male mice after in vivo treatment with arsenic Abstract: Male Swiss Albino mice were injected i.p. with an As2O3 solution (0; 4; 8 and 12 mg As/kg) and sacrificed 12, 24, 36 and 48 h after injection. Neither chromatid nor chromosome aberrations were observed in bone marrow cells and spermatogonia.",
Arsenic,2088462,"Pilot-scale investigation of the robustness and efficiency of a copper-based treated wood wastes recycling process Abstract: The disposal of metal-bearing treated wood wastes is becoming an environmental challenge. An efficient recycling process based on sulfuric acid leaching has been developed to remove metals from copper-based treated wood chips (0&lt;x&lt;12mm). The present study explored the performance and the robustness of this technology in removing metals from copper-based treated wood wastes at a pilot plant scale (130-L reactor tank). After 3× 2h leaching steps followed by 3× 7min rinsing steps, up to 97.5% of As, 87.9% of Cr, and 96.1% of Cu were removed from CCA-treated wood wastes with different initial metal loading (&gt;7.3kgm(-3)) and more than 94.5% of Cu was removed from ACQ-, CA- and MCQ-treated wood. The treatment of effluents by precipitation-coagulation was highly efficient; allowing removals more than 93% for the As, Cr, and Cu contained in the effluent. The economic analysis included operating costs, indirect costs and revenues related to remediated wood sales. The economic analysis concluded that CCA-treated wood wastes remediation can lead to a benefit of 53.7US$t(-1) or a cost of 35.5US$t(-1) and that ACQ-, CA- and MCQ-treated wood wastes recycling led to benefits ranging from 9.3 to 21.2US$t(-1).",
Arsenic,1936179,"Procedia Earth and Plantetary Science Geochemical comparison of high and low arsenic groundwater in the Hetao Basin, Inner Mongolia Abstract: ",
Arsenic,627885,"Arsenic exposure from drinking water, dietary intakes of B vitamins and folate, and risk of high blood pressure in Bangladesh: A population-based, cross-sectional study Abstract: The authors performed a cross-sectional analysis to evaluate the association between arsenic exposure from drinking water and blood pressure using baseline data of 10,910 participants in the Health Effects of Arsenic Longitudinal Study in Bangladesh (October 2000-May 2002). A time-weighted well arsenic concentration (TWA) based on current and past use of drinking wells was derived. Odds ratios for high pulse pressure (> or = 55 mmHg) by increasing TWA quintiles (< or = 8, 8.1-40.8, 40.9-91.0, 91.1-176.0, and 176.1-864.0 microg/liter) were 1.00 (referent), 1.39 (95% confidence interval (CI): 1.14, 1.71), 1.21 (95% CI: 0.99, 1.49), 1.19 (95% CI: 0.97, 1.45), and 1.19 (95% CI: 0.97, 1.46). Among participants with a lower than average dietary intake level of B vitamins and folate, the odds ratios for high pulse pressure by increasing TWA quintiles were 1.00 (referent), 1.84 (95% CI: 1.07, 3.16), 1.89 (95% CI: 1.11, 3.20), 1.83 (95% CI: 1.09, 3.07), and 1.89 (95% CI: 1.12, 3.20). The odds ratios for systolic hypertension suggest a similar but weaker association. No apparent associations were observed between TWA and general or diastolic hypertension. These findings indicate that the effect of low-level arsenic exposure on blood pressure is nonlinear and may be more pronounced in persons with lower intake of nutrients related to arsenic metabolism and cardiovascular health. Future research is needed to evaluate the effect of low-level arsenic exposure on specific cardiovascular outcomes.",
Arsenic,627198,"Inorganic arsenite-induced malignant transformation of human prostate epithelial cells Abstract: Although several epidemiologic studies show an association between arsenic exposure and prostate cancer, it is still unknown whether human prostate epithelial cells are directly susceptible to arsenic-induced transformation. This study was designed to determine whether the nontumorigenic human prostate epithelial cell line RWPE-1 could be malignantly transformed in vitro by arsenite. RWPE-1 cells were continuously exposed to 5 micro M arsenite and monitored for signs of transformation, assessed as changes in matrix metalloproteinase-9 levels. After 29 weeks of exposure, the arsenite-exposed RWPE-1 cells (referred to as CAsE-PE) showed a marked increase in matrix metalloproteinase-9 secretion, a common finding in prostate malignancies. Malignant transformation was confirmed when CAsE-PE cells produced aggressive undifferentiated malignant epithelial tumors in nude mice. The tumors stained positive for human prostate-specific antigen, confirming their origin. These results are the first report of arsenite-induced malignant transformation of a human epithelial cell line and provide an important in vitro model for studying the mechanisms underlying arsenic-induced carcinogenesis in humans.",
Arsenic,2278560,"Alpha-lipoic acid protects oxidative stress, changes in cholinergic system and tissue histopathology during co-exposure to arsenic-dichlorvos in rats Abstract: We investigated protective efficacy of ?-lipoic acid (LA), an antioxidant against arsenic and DDVP co-exposed rats. Biochemical variables suggestive of oxidative stress, neurological dysfunction, and tissue histopathological alterations were determined. Male rats were exposed either to 50ppm sodium arsenite in drinking water or in combination with DDVP (4mg/kg, subcutaneously) for 10 weeks. ?-Lipoic acid (50mg/kg, pos) was also co-administered in above groups. Arsenic exposure led to significant oxidative stress along, hepatotoxicity, hematotoxicity and altered brain biogenic amines levels accompanied by increased arsenic accumulation in blood and tissues. These altered biochemical variables were supported by histopathological examinations leading to oxidative stress and cell death. These biochemical alterations were significantly restored by co-administration of ?-lipoic acid with arsenic and DDVP alone and concomitantly. The results indicate that arsenic and DDVP induced oxidative stress and cholinergic dysfunction can be significantly protected by the supplementation of ?-lipoic acid.",
Arsenic,1357893,"Occupational Cancer in Israel Abstract: The occupational risk of cancer in Israel was discussed. Approximately 8000 new cancers, not counting basal cell and squamous cell carcinoma of the skin, were reported annually to the Israel Cancer Register. Of these, less than 5 percent were recognized by the National Insurance Institute as being of occupational origin; the rest were not eligible for workers' compensation benefits. It was postulated that cancers having male/female incidence ratios greater than 1.5 could be related to occupation since males represented the greater majority of workers in many occupation categories in Israel. A tabulation of cancer sites that had male/female incidence ratios greater than 1.5 was presented. These included cancer of the lip, mouth, nasopharynx, liver, nose and sinuses, larynx, lung and bronchus, connective tissue, kidney, and urinary bladder. Compounds recognized as being carcinogenic were listed. These included alkylating agents such as chloromethyl ethers, mustard-gas (505602), vinyl-chloride (75014), aromatic amines, benzene (71432), soot, tars, and mineral oils, diethylstilbestrol (56531), asbestos (1332214), arsenic (7440382), other minerals and metals, and mycotoxins. A policy for dealing with the problem of occupational exposure to carcinogenic agents that was being developed was outlined. It consisted of three stages: carcinogen identification, regulating and controlling carcinogenic compounds, and evaluating control programs.",
Arsenic,1344601,"Arsenic exposure, null genotypes of glutathione S-transferase M1, T1 and P1, and risk of carotid atherosclerosis among residents in the Lanyang Basin of Taiwan Abstract: In order to evaluate the synergistic effects of arsenic exposure through drinking water and genetic polymorphisms of GST M1, T1, and P1 on the risk of carotid atherosclerosis, a total of 605 residents who participated physical examination of arsenic-induced health effects held in Lanyang Basin were recruited as study subjects. A standardized personal interview based on a structured questionnaire was carried out to obtain information on duration of well water consumption, sociodemographic characteristics, cigarette smoking, alcohol drinking, as well as personal and family history of hypertension, diabetes and cerebrovascular disease. Well water samples were collected during the home interview. Hydride generator combined with flame atomic absorption spectrometry was used to determine the arsenic concentration in these samples. Whole blood samples were collected and centrifuged to separate buffy coat. DNA was then purified from buffy coat and stored at -20degreesC until genotyping. PCR was used for genotyping GSTM1 and GSTT1. PCR-RFLP was also carried out to determine the genetic polymorphisms of GST P1. Intimal-medial thickness (IMT) of arterial walls was measured by B-mode real-time ultrasound as an index of atherosclerosis. Plaque score was also used as an index of atherosclerosis. Logistic regression analysis was used to estimate age-sex-adjusted odds ratio and 95% confidence interval. Age was a major risk for the development of carotid atherosclerosis, showing a significant dose-response relationship. Compared with the youngest age group, the significant odds ratios of 5.9 and 2.3 were observed for the oldest and middle age groups, respectively. Significant risk for occurrence of carotid atherosclerosis was also observed among hypertension patients with age-sex-adjusted odds ratio of 2.4. Significant age-sex-adjusted odds ratios of risk of carotid atherosclerosis were observed in exposure groups with arsenic concentration in well water greater than 50 mug/l, showing odds ratio of 2.5. Moreover, study subjects with cumulative arsenic expo. sure greater than 1.0 mg/l-year also had significant age-sex-adjusted risk of developing carotid atherosclerosis. A significant higher age-sex-adjusted odds ratio of 2.0 for the development of carotid atherosclerosis was observed among study subjects with genotypes of W/M and M/M for GSTP1 A significant dose-response relationship was observed between risk of carotid atherosclerosis and,arsenic exposure indices of arsenic concentration in well water and cumulative arsenic exposure among study Subjects with null genotype of GSTM1 T1 and with W/M or M/M genotype of GSTP1. In conclusion, a significant effect on the risk of carotid atherosclerosis was observed among study subjects with arsenic exposure and with genotypes of W/M and M/M. In addition, significant synergistic effects on the risk for development of carotid atherosclerosis were also found between arsenic exposure and various genotypes of GST M1.",
Arsenic,1576388,"Characterization of particles in the ambience of the high-tech industrial park of Central Taiwan Abstract: Medical scholars have confirmed that prolonged exposure to high concentrations of suspended particles may result in respiratory and heart diseases. To identify the characteristics of particles around high-tech industrial parks, engaged in the manufacturing of semiconductors, electronics and electrical peripherals, this study performed a two-year monitoring program to measure the heavy metal composition in airborne particles in order to find the potential sources of pollution as well as the causal relationships between meteorological conditions and pollutant concentrations. Due to the complexity arising from the highly inter-related meteorological and topographical factors in local and regional wind fields, a comprehensive data-mining algorithm based on clustering analysis is proposed to explore the useful information obtained from the chaotic monitoring data sets, as well as to profile the pollution sources. Hierarchical cluster analysis confirms that the concentration of arsenic in fine particles significantly increased at the end of 2010, and increased in conditions of high relative humidity (50%-80%). During the periods with high wind speed, the amount of arsenic in fine particles increases and comes from the northeast. In contrast, dispersion controls the regional air quality at low wind speeds, and during such times the arsenic comes from the northwest.",
Arsenic,628539,"The role of biomethylation in toxicity and carcinogenicity of arsenic: A research update Abstract: Recent research of the metabolism and biological effects of arsenic has profoundly changed our understanding of the role of metabolism in modulation of toxicity and carcinogenicity of this metalloid. Historically, the enzymatic conversion of inorganic arsenic to mono- and dimethylated species has been considered a major mechanism for detoxification of inorganic arsenic. However, compelling experimental evidence obtained from several laboratories suggests that biomethylation, particularly the production of methylated metabolites that contain trivalent arsenic, is a process that activates arsenic as a toxin and a carcinogen. This article summarizes this evidence and provides new data on a) the toxicity of methylated trivalent arsenicals in mammalian cells, b) the effects of methylated trivalent arsenicals on gene transcription, and c) the mechanisms involved in arsenic methylation in animal and human tissues.",
Arsenic,1380160,"Vertebral defects in fourhorn sculpin, Myoxocephalus quadricornis L., exposed to heavy metal pollution in the Gulf of Bothnia Abstract: Vertebral defects in adult fourhorn sculpin were used to trace heavy metal pollution in the Gulf of Bothnia (Baltic Sea). From 1978 to 1984 a total of 9789 specimens from 22 localities were X-rayed and analysed for vertebral deformities, e.g., scoliosis, deformation and/or dislocation of individual vertebrae, etc. The frequency of fish with vertebral defects ranged between 4.3 and 39.7%, the highest frequencies being found in the vicinity of a metal ore smeltery (Rönnskärsverken) emitting heavy metals and arsenic. The possible influence of genetic factors, migration, sex, size, age and parasitic infections on the results are discussed and evaluated.",
Arsenic,1365248,"The function of heat-shock proteins in stress tolerance Abstract: We earlier demonstrated that hsp68 is deficiently induced upon stress in the glucocorticoid-resistant, dedifferentiated Reuber rat hepatoma clone 2 cells, but is strongly activated in the differentiated, glucocorticoid-sensitive Faza 967 cells from which clone 2 was derived. We used the two cell types to address the questions whether hsp68 is specifically involved in the development of thermotolerance and/or thermoresistance or drug resistance. Our experiments show that clone 2 cells were not protected from the killing effect of heat by pre-treatment with sodium arsenite, whereas Faza 967 cells were. These results strongly suggest a role of hsp68 in the development of thermotolerance in hepatoma cells. Stable heat-resistant variants of clone 2 cells were also isolated, where an increased basal expression of several hsps was observed together with the (at least partial) restoration of the heat-inducibility of hsp68. These results suggest that several hsps are needed to protect the critical biological processes at high temperature. The heat-resistant hepatoma cells also became resistant to several anticancer drugs. The multidrug resistance of the hepatoma variants correlates with the overexpression of the plasma membrane P-glycoprotein. Our results showing that severely stressed hepatoma cells overexpressed the mdr gene(s) raise the possibility that the P-gp may participate in protection against environmental stress such as heat.",
Arsenic,1025903,"The mysterious death of America's richest woman in 1917, Mary Lil' (RIP) Abstract: Suspicious circumstances surrounding the death of wealthy socialite Mary Lily Lil' Kenan Flagler Bingham in 1917 prompted a secret autopsy conducted by renowned physicians at the request of her relatives. Mrs Bingham, who was formerly married to railroad magnate, Henry Flagler, was among America's richest people at the time of her death. Mary Lil's untimely death occurred approximately six months after her marriage to Judge Robert Bob Worth Bingham, a college boyfriend whom she married three years after Flagler's death. In order to establish Mary Lil's medical condition prior to her death, a book about Mary Lil's life written by Pulitzer Prize author, David Chandler and articles from the New York Times; The Louisville Courier Journal, a Kentucky newspaper; and Mary Lil's hometown newspaper, The Morning Star, in Wilmington, North Carolina were examined. Although a team of medical experts performed a secret autopsy following her death and released their findings to her family, the examination and tests results remain undisclosed to the public.",
Arsenic,1070499,"Towards prenatal biomonitoring in North Carolina: assessing arsenic, cadmium, mercury, and lead levels in pregnant women Abstract: Exposure to toxic metals during the prenatal period carries the potential for adverse developmental effects to the fetus, yet such exposure remains largely unmonitored in the United States. The aim of this study was to assess maternal exposure to four toxic metals (arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb)) in a cohort of pregnant women in North Carolina. We analyzed blood samples submitted to the North Carolina Department of Health and Human Services for blood typing to assess toxic metal levels in pregnant women (n = 211) across six North Carolina counties. Whole blood metal concentrations were measured by inductively coupled plasma mass spectrometry. The association between maternal characteristics, including county of residence, age, and race, and metal exposure was analyzed using multiple linear regression analysis. A large fraction of the blood samples showed detectable levels for each of the four metals. Specifically, As (65.7%), Cd (57.3%), Hg (63.8%), and Pb (100%) were detected in blood samples. Moreover, compared with adult females participating in the Fourth National Report on Human Exposure to Environmental Chemicals and guidelines for pregnant women, some women in the sample population exceeded benchmark levels of Cd, Hg, and Pb. Evidence from this pilot study indicates that pregnant women in North Carolina are exposed to As, Cd, Hg, and Pb and suggests that factors related to maternal county of residence and race may impact maternal exposure levels. As increased levels of one or more of these metals in utero have been associated with detrimental developmental and reproductive outcomes, further study is clearly warranted to establish the impacts to newborns.",
Arsenic,1019260,"Biological monitoring of occupational exposure to inorganic arsenic Abstract: OBJECTIVES: This study was undertaken to assess reliable biological indicators for monitoring the occupational exposure to inorganic arsenic (iAs), taking into account the possible confounding role of arsenicals present in food and of the element present in drinking water. METHODS: 51 Glass workers exposed to As trioxide were monitored by measuring dust in the breathing zone, with personal air samplers. Urine samples at the end of work shift were analysed for biological monitoring. A control group of 39 subjects not exposed to As, and eight volunteers who drank water containing about 45 micrograms/l iAs for a week were also considered. Plasma mass spectrometry (ICP-MS) was used for the analysis of total As in air and urine samples, whereas the urinary As species (trivalent, As3; pentavalent, As5; monomethyl arsonic acid, MMA; dimethyl arsinic acid, DMA; arsenobetaine, AsB) were measured by liquid chromatography coupled with plasma mass spectrometry (HPLC-MS) RESULTS: Environmental concentrations of As in air varied widely (mean 84 micrograms/m3, SD 61, median 40) and also the sum of urinary iAs MMA and DMA, varied among the groups of exposed subjects (mean 106 micrograms/l, SD 84, median 65). AsB was the most excreted species (34% of total As) followed by DMA (28%), MMA (26%), and As3 + As5 (12%). In the volunteers who drank As in the water the excretion of MMA and DMA increased (from a median of 0.5 to 5 micrograms/day for MMA and from 4 to 13 micrograms/day for DMA). The best correlations between As in air and its urinary species were found for total iAs and As3 + As5. CONCLUSIONS: To avoid the effect of As from sources other than occupation on urinary species of the element, in particular on DMA, it is proposed that urinary As3 + As5 may an indicator for monitoring the exposure to iAs. For concentrations of 10 micrograms/m3 the current environmental limit for iAs, the limit for urinary As3 + As5 was calculated to be around 5 micrograms/l, even if the wide variation of values needs critical evaluation and application of data. The choice of this indicator might be relevant also from a toxicological point of view. Trivalent arsenic is in fact the most active species and its measure in urine could be the best indicator of some critical effects of the element, such as cancer.",
Arsenic,1026592,"Micronuclei and chromosomal aberrations as biomarkers: A study in an arsenic exposed population in West Bengal, India Abstract: ",
Arsenic,1017423,"Evaluation of a social marketing campaign to support Mexico City's comprehensive smoke-free law Abstract: <strong>OBJECTIVES: </strong>We aimed to assess the level of awareness and impact of a social marketing campaign to promote Mexico City's 2008 comprehensive smoke-free law.<br /><br /><strong>METHODS: </strong>Four months after the smoke-free law was implemented but before the campaign launch, we collected data from a population-based, random sample of 961 inhabitants of Mexico City. We analyzed data from 786 respondents who completed follow-up at the end of the campaign to determine campaign exposure and the association between campaign exposure and changes in campaign-targeted knowledge and attitudes.<br /><br /><strong>RESULTS: </strong>Recall of any of the 5 campaign materials was 69%, with a uniform distribution of exposure to 1, 2, and 3 or more campaign materials (25%, 25%, and 19%, respectively). Exposure to a greater number of campaign materials was associated in a monotonic relation with campaign-targeted knowledge of ammonia and arsenic in cigarette smoke. In models assessing support for, perceived benefits of, and perceived right to smoke-free places, campaign exposure accounted for a positive change in half of the indicators within each of these domains.<br /><br /><strong>CONCLUSIONS: </strong>Social marketing campaigns can reinforce knowledge and attitudes that favor smoke-free laws, thereby helping to establish smoke-free norms.",
Arsenic,2088333,"Study of arsenic-containing borates based on transformation products of industrial waste Abstract: The novel arsenic-containing borates have been synthesized and studied. The composition and structure of the synthesized compounds have been established by physico-chemical analysis, IR, NMR and Mass spectral studies. Preliminary virtual (theoretical) bioscreening of synthesized compounds have been carried out. Biocide properties of obtained compounds were also determined.",
Arsenic,1339972,"Associations between toenail arsenic concentration and dietary factors in a New Hampshire population Abstract: <strong>BACKGROUND: </strong>Dietary factors such as folate, vitamin B12, protein, and methionine are important for the excretion of arsenic via one-carbon metabolism in undernourished populations exposed to high levels of arsenic via drinking water. However, the effects of dietary factors on toenail arsenic concentrations in well-nourished populations exposed to relatively low levels of water arsenic are unknown.<br /><br /><strong>METHODS: </strong>As part of a population-based case-control study of skin and bladder cancer from the USA, we evaluated relationships between consumption of dietary factors and arsenic concentrations in toenail clippings. Consumption of each dietary factor was determined from a validated food frequency questionnaire. We used general linear models to examine the associations between toenail arsenic and each dietary factor, taking into account potentially confounding effects.<br /><br /><strong>RESULTS: </strong>As expected, we found an inverse association between ln-transformed toenail arsenic and consumption of vitamin B12 (excluding supplements) and animal protein. Unexpectedly, there were also inverse associations with numerous dietary lipids (e.g., total fat, total animal fat, total vegetable fat, total monounsaturated fat, total polyunsaturated fat, and total saturated fat). Finally, increased toenail arsenic concentrations were associated with increased consumption of long chain n-3 fatty acids.<br /><br /><strong>CONCLUSION: </strong>In a relatively well-nourished population exposed to relatively low levels of arsenic via water, consumption of certain dietary lipids may decrease toenail arsenic concentration, while long chain n-3 fatty acids may increase toenail arsenic concentration, possibly due to their association with arsenolipids in fish tissue.",
Arsenic,627321,"Arsenic targets tubulins to induce apoptosis in myeloid leukemia cells Abstract: Arsenic exhibits a differential toxicity to cancer cells. At a high concentration (>5 microM), As2O3 causes acute necrosis in various cell lines. At a lower concentration (0.5-5 microm), it induces myeloid cell maturation and an arrest in metaphase, leading to apoptosis. As2O3-treated cells have features found with both tubulin-assembling enhancers (Taxol) and inhibitors (colchicine). Prior treatment of monomeric tubulin with As2O3 markedly inhibits GTP-induced polymerization and microtubule formation in vitro but does not destabilize GTP-induced tubulin polymers. Cross-inhibition experiments indicate that As2O3 is a noncompetitive inhibitor of GTP binding to tubulin. These observations correlate with the three-dimensional structure of beta-tubulin and suggest that the cross-linking of two vicinal cysteine residues (Cys-12 and Cys-213) by trivalent arsenic inactivates the GTP binding site. Furthermore, exogenous GTP can prevent As2O3-induced mitotic arrest.",
Arsenic,1015967,"Analysis of arsenic metabolites in HepG2 and AS3MT-transfected cells Abstract: It has been suggested that arsenic (+3 oxidation state) methyltransferase (AS3MT) plays a critical role in methylation of arsenic, and that arsenic-glutathione conjugate is a substrate for AS3MT-catalyzed methylation of arsenic. However, the mechanism of arsenic methylation in cells is not fully understood. Here, we have constructed T-REx-CHO-hAS3MTtr cells that transiently overexpress human AS3MT in response to tetracycline. The decreases in cell viability after exposure to sodium arsenite were greater in tetracycline-treated cells (tet(+) cells) than in untreated cells (tet(-) cells). Concentration of total cellular arsenic was significantly higher in tet(+) cells than in tet(-) cells. Speciation analyses of arsenic metabolites in whole cell lysates and cell culture medium were performed using both HepG2 cells and T-REx-CHO-hAS3MTtr cells. Speciation analyses of arsenic metabolites in lysates of T-REx-CHO-hAS3MTtr cells revealed that dimethylated arsenicals were the predominant arsenic metabolites in tet(+) cells, while methylated metabolites were not found in tet(-) cells. In contrast, less amount of methylated arsenic metabolites were found in the HepG2 cell lysates, and monomethylated trivalent arsenicals were the predominant methylated arsenic metabolites. Arsenate was found in the culture medium after 24 h culture with arsenite. A larger amount of arsenate was found in the culture medium of tet(+) or tet(-) cells compared to HepG2 cells. These findings indicated that AS3MT expression enhanced the cytotoxic effect of arsenite in tet(+) cells because these cells accumulated more arsenic metabolites than did the tet(-) cells, and accordingly, the tet(+) cells were more susceptible to arsenic than were the tet(-) cells. Oxidation--reduction of arsenic may be implicated in the toxic effects of arsenite.",
Arsenic,627846,"Levels of urinary total and speciated arsenic in the US population: National Health and Nutrition Examination Survey 2003-2004 Abstract: OBJECTIVE: To provide levels of total and speciated urinary arsenic in a representative sample of the US population. METHODS: For the first time, total arsenic and seven inorganic and organic arsenic species were measured in the urine of participants (n=2557) for the 2003-2004 National Health and Nutrition Examination Survey (NHANES). Data were compiled as geometric means and selected percentiles of urinary arsenic concentrations (microg/l) and creatinine-corrected urinary arsenic (microg/g creatinine) for total arsenic, dimethylarsinic acid, arsenobetaine, and a sum of the inorganic related species. RESULTS:Arsenic acid, arsenous acid, arsenocholine, and trimethylarsine oxide were detected in 7.6%, 4.6%, 1.8%, and 0.3% of the participants, respectively (the limits of detection of 0.6-1.2 microg/l). Monomethylarsonic acid was detected in 35% of the overall population. For all participants aged > or =6 years, dimethylarsinic acid (geometric mean of 3.71 microg/l) and arsenobetaine (geometric mean of 1.55 microg/l) had the greatest contribution to the total urinary arsenic levels. A relatively greater percentage contribution from arsenobetaine is seen at higher total urinary arsenic levels and from dimethylarsinic acid at lower total urinary arsenic levels. For all participants aged > or =6 years, the 95th percentiles for total urinary arsenic and the sum of inorganic-related arsenic (arsenic acid, arsenous acid, dimethylarsinic acid, and monomethylarsonic acid) were 65.4 and 18.9 microg/l, respectively. For total arsenic and dimethylarsinic acid, covariate-adjusted geometric means demonstrated several slight differences due to age, gender, and race/ethnicity. CONCLUSIONS:The data reflect relative background contributions of inorganic and seafood-related arsenic exposures in the US population. Arsenobetaine and dimethylarsinic acid are the major arsenic species present with arsenobetaine, accounting for a greater proportion of total arsenic as total arsenic levels increase.",
Arsenic,1240301,"Molecular identification and analysis of arsenite stress-responsive miRNAs in rice Abstract: Arsenic is highly toxic to living organisms including humans and plants. To investigate the responsive functions of miRNAs under arsenite stress, an indica rice, Minghui 86, has been deeply sequenced, and a total of 67 arsenite-responsive miRNAs were identified in rice seedling roots, of which 5 were further validated experimentally. The potential targets of those differential miRNAs include some transcription factors, protein kinases, and DNA- or metal ion-binding proteins that are associated with cellular and metabolic processes, pigmentation, and stress responses. The regulatory roles of four miRNAs on their targets in response to arsenite were further confirmed by real time RT-PCR. Interestingly, osa-miR6256 was originally characterized as a putative exonic miRNA, supporting the notion that miRNAs may also originate from some exons in plants. The first identification of arsenite-responsive miRNAs at the whole genome-wide level will broaden the current understanding of the molecular mechanisms of arsenite responses in rice.",
Arsenic,1247799,"EMT and Stem Cell-Like Properties Associated with HIF-2? Are Involved in Arsenite-Induced Transformation of Human Bronchial Epithelial Cells Abstract: <strong>BACKGROUND: </strong>Arsenic is well-established as a human carcinogen, but the molecular mechanisms leading to arsenic-induced carcinogenesis are complex and elusive. It is not been determined if the epithelial-mesenchymal transition (EMT) and stem cell-like properties contribute in causing to carcinogen-induced malignant transformation and subsequent tumor formation.<br /><br /><strong>METHODS: </strong>To investigate the molecular mechanisms underlying EMT and the emergence of cancer stem cell-like properties during neoplastic transformation of human bronchial epithelial (HBE) cells induced by chronic exposure to arsenite. HBE cells were continuously exposed to arsenite. Spheroid formation assays and analyses of side populations (SPs) were performed to confirm that arsenite induces the acquired EMT and cancer stem cell-like phenotype. Treated HBE cells were molecularly characterized by RT-PCR, Western blots, immunofluorescence, Southwestern assays, reporter assays, and chromatin immunoprecipitation.<br /><br /><strong>RESULTS: </strong>With chronic exposure to arsenite, HBE cells undergo an EMT and then acquire a malignant cancer stem cell-like phenotype. Twist1 and Bmi1 are involved in arsenite-induced EMT. The process is directly regulated by HIF-2?. The self-renewal genes, Oct4, Bmi1, and ALDH1, are necessary for arsenite-mediated maintenance of stem cells.<br /><br /><strong>CONCLUSIONS: </strong>EMT, regulated by HIF-2?, and the development of a cancer stem cell-like phenotype are associated with arsenite-induced transformation of HBE cells.",
Arsenic,1337464,"Computational modelling of the volatile hydride fragmentation in a dielectric barrier discharge atomizer Abstract: In this study, we present a model whereby a fragmentation of arsenic hydride in a rectangular dielectric barrier discharge (DBD) atomizer is investigated. The aim is to elucidate the distribution of the intermediates species and generated free analyte atoms along atomizer channel, which is required to decide the optimal position for spectrometric data acquisition. Simulation results indicate that formation of intermediate species and free arsenic atoms is initiated in the first section of atomization channel before reaching the section between the electrodes. Moreover, concentration of free arsenic atoms saturates to a maximum and does not vary thereafter along atomization channel. This result could be attributed to the presence of abundance of hydrogen radicals along atomization channel which limits recombination reactions and ultimately maintains free atom life, which is so useful for analytical purposes. This outcome suggests an approach for radial data acquisition from any position along DBD atomization channel with same sensitivity. Furthermore, this result indicates that DBD atomizer is appropriate for analytical purposes and competitive to other well known atomization tools such as a quartz cell atomizer.  The model has been verified experimentally upon examining arsenic and mercury qualitatively from applying chemical vapour generation techniques. Approximately similar results obtained from three radial positions along the atomization channel, whereas a significant increase in signal intensity observed when applying axial viewing by 22 and 40% for arsenic and mercury respectively.  Furthermore, a quantitative determination for arsenic is also tried; however, the results were found not useful for model validation due to the hydrogen magnification effect on the recorded spectrum.",
Arsenic,1677615,"Invasive infections caused by Streptococcus pneumoniae in a terciary care pediatric hospital before the introduction of the conjugate vaccine: Clinical characteristics and serotypes involved Abstract: Invasive pneumococcal diseases are the main cause of morbidity and mortality in children. In the Hospital &quot;Prof. Dr. Juan P. Garrahan&quot;, between October 1st , 2008 and September 30th, 2011 all invasive pneumococcal diseases with positive blood cultures were retrospectively studied before the implementation of the universal immunization schedule with the 13-valent pneumococcal conjugate vaccine. A total of 124 patients were identified, and their mean age was 48.3 months (range: 1-216). In this population, 58.9% (n: 73) were OVER 2 years old and 89% (n: 65) of them had an underlying disease. The most frequent clinical presentation was pneumonia. The most frequent S. pneumoniae serotypes identified were: 14 (22.5%, n: 25), 6 (14.4%, n: 16), 19 (8.1%, n: 9), 23 (7.2%, n: 8), 1 (6.3%, n: 7), 5 (4.5%, n: 5), and 7 (7.2%, n: 8). Of the S. pneumoniae serotypes in this series, 82.2% is included in the 13-valent pneumococcal conjugate vaccine. Continuous epidemiological surveillance is essential to further identify the epidemiology and study the evolution of invasive pneumococcal disease in Argentina.",
Arsenic,2298729,"Evaluation of potential effects of soil available phosphorus on soil arsenic availability and paddy rice inorganic arsenic content Abstract: The transfer of arsenic from paddy field to rice is a major exposure route of the highly toxic element to humans. The aim of our study is to explore the effects of soil available phosphorus on As uptake by rice, and identify the effects of soil properties on arsenic transfer from soil to rice under actual field conditions. 56 pairs of topsoil and rice samples were collected. The relevant parameters in soil and the inorganic arsenic in rice grains were analyzed, and then all the results were treated by statistical methods. Results show that the main factors influencing the uptake by rice grain include soil pH and available phosphorus. The eventual impact of phosphorus is identified as the suppression of As uptake by rice grains. The competition for transporters from soil to roots between arsenic and phosphorus in rhizosphere soil has been a dominant feature.",
Arsenic,1018930,"Stress-related gene expression in mice treated with inorganic arsenicals Abstract: Arsenic (As) is an environmental chemical of high concern for human health. Acute toxicity of arsenic is dependent on its chemical forms and proximity to high local arsenic concentrations is one of the mechanisms for cell death. This study was designed to define acute arsenic-induced stress-related gene expression in vivo. Mice were injected sc with either sodium arsenite [As(III), 100 micromol/kg], sodium arsenate [As(V), 300 micromol/kg], or saline. To examine stress-related gene expression, livers were removed 3 h after arsenic injection for RNA and protein extraction. The Atlas Mouse Stress/Toxicology array revealed that the expression of genes related to stress, DNA damage, and metabolism was altered by acute arsenic treatments. Expression of heme oxygenase 1 (HO-1), a hallmark for arsenic-induced stress, was increased 10-fold, along with increases in heat shock protein-60 (HSP60), DNA damage inducible protein GADD45, and the DNA excision repair protein ERCC1. Downregulation of certain cytochrome P450 enzymes occurred with arsenic treatment. Multiprobe RNase protection assay revealed the activation of the c-Jun/AP-1 transcription complex after arsenic treatments. Western blot analysis further confirmed the enhanced production of arsenic-induced stress proteins such as HO-1, HSP70, HSP90, metallothionein, the metal-responsive transcription factor MTF-1, nuclear factor kappa B and c-Jun/AP-1. Increases in caspase-1 and cytokines such as tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-2 were also evident. In summary, this study profiled the gene expression pattern in mice treated with inorganic arsenicals, which adds to our understanding of acute arsenic poisoning and toxicity.",
Arsenic,1508541,"Potentially-toxic and essential elements profile of AH1N1 patients in Mexico City Abstract: During spring of 2009, a new influenza virus AH1N1 spread in the world causing acute respiratory illness and death, resulting in the first influenza pandemic since 1968. Blood levels of potentially-toxic and essential elements of 40 pneumonia and confirmed AH1N1 were evaluated against two different groups of controls, both not infected with the pandemic strain. Significant concentrations of potentially-toxic elements (lead, mercury, cadmium, chromium, arsenic) along with deficiency of selenium or increased Zn/Cu ratios characterized AH1N1 cases under study when evaluated versus controlled cases. Deficiency of selenium is progressively observed from controls I (influenza like illness) through controls II (pneumonia) and finally pneumonia -AH1N1 infected patients. Cases with blood Se levels greater than the recommended for an optimal cut-off to activate glutathione peroxidase (12.5??g/dL) recovered from illness and survived. Evaluation of this essential element in critical pneumonia patients at the National Institutes is under evaluation as a clinical trial.",
Arsenic,502724,"Interaction of aluminum with admixtures dissolved in liquid lead Abstract: The behavior of antimony, tin, copper, bismuth, and arsenic admixtures during refining black lead with aluminum application was considered.",
Arsenic,1797826,"Mobility and distribution of arsenic in contaminated mine soils and its effects on the microbial pool Abstract: Three soils, coming from a former mining site and characterized by a different degree of pollution, were analysed in terms of Arsenic (As) content, using three different analytical approaches, and its distribution in various soil fractions. The effect of As on soil microbial biomass (size, respiration and microbial quotients) was also analysed. Total arsenic concentration between soil fractions was significantly different and ranged from 189 to 4357mgkg(-1), indicating a high level of pollution. Soil sequential fractioning showed that more than 60 percent of total As was bound to Fe-Al oxides, suggesting a minor availability and environmental risk regardless the total concentration of As in the sample. On the contrary, water soluble As fraction showed a significant difference among the three samples. The largest water soluble As concentration was found in the sample with intermediate total As amount. As far as microbial biomass is concerned, it was found that bioavailable As negatively impacted microbial metabolism in terms of basal and cumulative respiration, and microbial quotients, suggesting a strong selection within microbial pool.",
Arsenic,2345647,"Trace metal quantification in bladder biopsies from tumoral lesions of Tunisian cancer and controls subjects Abstract: The incidence of bladder tumors has been dramatically increasing since the 1970s, possibly as a consequence of ongoing environmental pollution. Previous studies have provided some evidence of an association between cancer and exposure to carcinogenic metals. In order to examine the association between levels of toxic metals in patients with bladder tumors and controls, the amounts of arsenic, cadmium, chromium, and nickel were measured in tumoral lesions and adjacent normal part of the bladder mucosa excised for carcinoma and compared with those in the bladder mucosa of volunteer subjects operated for non-neoplastic diseases. The quantification of metals in tissue was assessed by atomic absorption spectroscopy. In tumoral tissues of the excised bladder mucosa, content of Cr and Ni was significantly low compared to that of adjacent normal tissues and control tissues while that of As and Cd in normal tissues adjacent to the tumor were significantly elevated compared to controls. Though the sample size was small, the present study shows that concentrations of metals such as Cd, Cr, As, and Ni in bladder tissue may be used as a biomarker of exposure. On the basis of the results obtained in this study, high amounts of As and Cd in adjacent normal parts of the bladders with carcinomas compared to controls would strongly suggest possible, individual or synergistic, effects of these pollutants on enzymatic systems, priming an oncogenic pathway.",
Arsenic,1018920,"In vitro effect of arsenical compounds on glutathione-related enzymes Abstract: The mechanism of arsenic toxicity is believed to be due to the ability of arsenite (As(III)) to bind protein thiols. Glutathione (GSH) is the most abundant cellular thiol, and both GSH and GSH-related enzymes are important antioxidants that play an important role in the detoxification of arsenic and other carcinogens. The effect of arsenic on the activity of a variety of enzymes that use GSH has been determined using purified preparations of glutathione reductase (GR) from yeast and bovine glutathione peroxidase (GPx) and equine glutathione S-transferase (GST). The effect on enzyme activity of increasing concentrations (from 1 microM to 100 mM) of commercial sodium arsenite (As(III)) and sodium arsenate (As(V)) and a prepared arsenic(III)-glutathione complex [As(III)(GS)(3)] and methylarsenous diiodide (CH(3)As(III)) has been examined. GR, GPx, and GST are not sensitive to As(V) (IC(50) &gt; 50 mM), and none of the enzymes are inhibited or activated by physiologically relevant concentrations of As(III), As(III)(GS)(3), or CH(3)As(III), although CH(3)As(III) is the most potent inhibitor (0.3 mM &lt; IC(50) &lt; 1.5 mM). GPx is the most sensitive to arsenic treatment and GST the least. Our results do not implicate a direct interaction of As with the glutathione-related enzymes, GR, GPx, and GST, in the mechanism of arsenic toxicity. CH(3)As(III) is the most effective inhibitor, but it is unclear whether this product of arsenic metabolism is produced at a sufficiently high concentration in critical target tissues to play a major role in either arsenic toxicity or carcinogenesis.",
Arsenic,1034324,"Cumulative exposure to arsenic and its relationship to respiratory cancer among copper smelter employees Abstract: To explore the role of arsenic as a human carcinogen, the respiratory cancer mortality experience (1938 to 1977) of 8,045 while male smelter employees in Montana was examined relative to cumulative exposure to arsenic trioxide and was compared with that of the white male population of the same region. Exposure to arsenic was estimated for various work areas from industrial hygiene reports of average concentrations present in the smelter. Respiratory cancer mortality was analyzed further by time period of first employment and maximum lifetime exposure to arsenic trioxide. When exposure was estimated with arithmetic means of measured concentrations among men first employed prior to 1925, respiratory cancer mortality increased linearly with increasing cumulative exposure group, ranging from two to nine times expected; among those first employed in the period 1925 to 1947 it also increased linearly with increasing cumulative exposure group.",
Arsenic,1677386,"Predicting water quality criteria for protecting aquatic life from physicochemical properties of metals or metalloids Abstract: Metals are widely distributed pollutants in water and can have detrimental effects on some aquatic life and humans. Over the past few decades, the United States Environmental Protection Agency (U.S. EPA) has published a series of criteria guidelines, which contain specific criteria maximum concentrations (CMCs) for 10 metals. However, CMCs for other metals are still lacking because of financial, practical, or ethical restrictions on toxicity testing. Herein, a quantitative structure activity relationship (QSAR) method was used to develop a set of predictive relationships, based on physical and chemical characteristics of metals, and predict acute toxicities of each species for five phyla and eight families of organisms for 25 metals or metalloids. In addition, species sensitivity distributions (SSDs) were developed as independent methods for determining predictive CMCs. The quantitative ion character-activity relationships (QICAR) analysis showed that the softness index (?p), maximum complex stability constants (log -?(n)), electrochemical potential (?E(0)), and covalent index (X(m)(2)r) were the minimum set of structure parameters required to predict toxicity of metals to eight families of representative organisms. Predicted CMCs for 10 metals are in reasonable agreement with those recommended previously by U.S. EPA within a difference of 1.5 orders of magnitude. CMCs were significantly related to ?p (r(2) = 0.76, P = 7.02 × 10(-9)) and log -?(n) (r(2) = 0.73, P = 3.88 × 10(-8)). The novel QICAR-SSD model reported here is a rapid, cost-effective, and reasonably accurate method, which can provide a beneficial supplement to existing methodologies for developing preliminarily screen level toxicities or criteria for metals, for which little or no relevant information on the toxicity to particular classes of aquatic organisms exists.",
Arsenic,1508696,"A vibrational spectroscopic study of philipsbornite PbAl(3)(AsO(4))(2)(OH)(5)?H(2)O-molecular structural implications and relationship to the crandallite subgroup arsenates Abstract: The presence of arsenic in the environment is a hazard. The accumulation of arsenate by a range of cations in the formation of minerals provides a mechanism for the remediation of arsenate contamination. The formation of the crandallite group of minerals provides a mechanism for arsenate accumulation. Among the crandallite minerals are philipsbornite, arsenocrandallite and arsenogoyazite. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of philipsbornite to be studied. The Raman spectrum of philipsbornite displays an intense band at around 840cm(-1) attributed to the overlap of the symmetric and antisymmetric stretching modes. Raman bands observed at 325, 336, 347, 357, 376 and 399cm(-1) are assigned to the ?(2) (AsO(4))(3-) symmetric bending vibration (E) and to the ?(4) bending vibration (F(2)). The observation of multiple bending modes supports the concept of a reduction in symmetry of the arsenate anion in philipsbornite. Evidence for phosphate in the mineral is provided. By using an empirical formula, hydrogen bond distances for the OH units in philipsbornite of 2.8648Å, 2.7864Å, 2.6896Åcm(-1) and 2.6220 were calculated.",
Arsenic,628040,"Sub-toxic arsenite induces a multi-component protective response against oxidative stress in human cells Abstract: We have investigated the effect of arsenite, As(III), on cultured human keratinocytes and fibroblasts looking at the activity of glutathione-related enzymes, DNA repair function, and the expression of both redox-related and DNA repair genes. We have found that genes related to both cellular redox control and base excision repair are coordinately up-regulated by very low (essentially non-toxic) doses of As(III). The DNA repair genes are then down-regulated by slightly higher doses of As(III).This correlates with our finding that pre-treatment with arsenite can modulate the toxicity of DNA damaging agents in a manner that is consistent with the induction of a protective response by a very low dose of As(Ill) combined with synergistic toxicity at higher doses. Our data provide strong evidence that a low dose of As(III) provokes a multi-faceted protective response against further insults of oxidative stress. Yet, at slightly higher doses arsenite exhibits strong synergistic toxicity with these same agents. These results suggest that caution is warranted when assessing risk due to arsenic exposure among human populations since we do not know if long-term exposure might not lead to persistent changes in cellular regulation or homeostasis. It is clear, however, that a linear extrapolation of risk based on exposure to high, toxic concentrations of arsenic cannot adequately predict response to low, sub-toxic concentrations.",
Arsenic,1031500,"Combined in utero and juvenile exposure of mice to arsenate and atrazine in drinking water modulates gene expression and clonogenicity of myeloid progenitors Abstract: The effects of arsenate (As) and atrazine (Atr) on myeloid progenitors (colony-forming unit-granulocyte/macrophage, CFU-GM) cells derived from bone marrow were studied in male and female mice after combined in utero and juvenile exposure. Female adult mice were treated with arsenate in drinking water during gestation. Then, separate groups of males and females' offspring were exposed for 4 months to atrazine, to additional arsenate or to co-exposure of atrazine and arsenate together in drinking water. In male mice, arsenate and the combined exposure did not modulate the percentage of CFU-GM progenitors, whereas atrazine significantly decreases the clonogenicity of myeloid cells. In females, the percentage of CFU-GM significantly decreased after atrazine exposure did not change with arsenate treatment, but dramatically increased after the combined exposure. The expression of estrogen receptors alpha (ERalpha) and beta (ERbeta) in bone marrow cells was investigated, and an up-regulation of receptor beta was observed in both genders. A gene expression profile was generated using nylon membranes spotted with 1185 cancer-related genes. Results from microarrays indicate that atrazine alone did not stimulate the expression of any of the genes analysed in both male and female. Arsenic induced gene expression modulation only in female. Major significant changes on the gene expression resulted following the co-exposure to arsenic and atrazine in both male and female.",
Arsenic,1339829,"Exposure of soil microbial communities to chromium and arsenic alters their diversity and structure Abstract: Extensive use of chromium (Cr) and arsenic (As) based preservatives from the leather tanning industry in Pakistan has had a deleterious effect on the soils surrounding production facilities. Bacteria have been shown to be an active component in the geochemical cycling of both Cr and As, but it is unknown how these compounds affect microbial community composition or the prevalence and form of metal resistance. Therefore, we sought to understand the effects that long-term exposure to As and Cr had on the diversity and structure of soil microbial communities. Soils from three spatially isolated tanning facilities in the Punjab province of Pakistan were analyzed. The structure, diversity and abundance of microbial 16S rRNA genes were highly influenced by the concentration and presence of hexavalent chromium (Cr (VI)) and arsenic. When compared to control soils, contaminated soils were dominated by Proteobacteria while Actinobacteria and Acidobacteria (which are generally abundant in pristine soils) were minor components of the bacterial community. Shifts in community composition were significant and revealed that Cr (VI)-containing soils were more similar to each other than to As contaminated soils lacking Cr (VI). Diversity of the arsenic resistance genes, arsB and ACR3 were also determined. Results showed that ACR3 becomes less diverse as arsenic concentrations increase with a single OTU dominating at the highest concentration. Chronic exposure to either Cr or As not only alters the composition of the soil bacterial community in general, but affects the arsenic resistant individuals in different ways.",
Arsenic,2042181,"Synthesis of sludge@carbon nanocomposite for the recovery of As(V) from wastewater Abstract: A novel type of sludge@carbon nanocomposite was synthesized using municipal sewage sludge as raw material and ferrous iron sulphate as catalyst through hydrothermal carbonization (HTC) process. The prepared adsorbent was characterized by various analytical techniques as Scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction patterns (XRD). The adsorption capacity of this nanocomposite for As(V) has been studied using a batch method. Various parameters affecting sorption such as pH, contact time and sorbate concentration were investigated and optimal experimental conditions were determined. It was found that 0.5 h was sufficient for complete removal of 0.5 mg/l As(V) from polluted water. The suitable adsorbent dosage and pH value were 3.6 g/l and 5.0, respectively. The arsenic desorbed could subsequently be separated by 0.5M NaOH solution. A modified linear driving force model conjugated with Langmuir isotherm was created to describe the adsorption kinetics. The resultant modified sewage sludge demonstrated a substantially high adsorption capacity of As(V) in comparison with dried sewage sludge and many other adsorbents reported in literature. The rates of adsorption were found to conform to the pseudo-second order kinetic model. The intra-particle diffusion was identified to be the ratelimiting step. The sludge@carbon nanocomposite could be reused after two adsorption-desorption cycles.",
Arsenic,628601,"Aberrant DNA methylation and gene expression in livers of newborn mice transplacentally exposed to a hepatocarcinogenic dose of inorganic arsenic Abstract: Our prior work showed that brief exposure of pregnant C3H mice to inorganic arsenic-induced hepatocellular carcinoma (HCC) formation in adult male offspring. The current study examined the early hepatic events associated with this oncogenic transformation. Pregnant mice were exposed to a known carcinogenic dose of arsenic (85 ppm) in the drinking water from gestation days 8 to 18. The dams were allowed to give birth and liver samples from newborn males were analyzed for arsenic content, global DNA methylation and aberrant expression of genes relevant to the carcinogenic process. Arsenic content in newborn liver reached 57 ng/g wet weight, indicating arsenic had crossed the placenta, reached the fetal liver and that significant amounts remained after birth. Global methylation status of hepatic DNA was not altered by arsenic in the newborn. However, a significant reduction in methylation occurred globally in GC-rich regions. Microarray and real-time RT-PCR analysis showed that arsenic exposure enhanced expression of genes encoding for glutathione production and caused aberrant expression of genes related to insulin growth factor signaling pathways and cytochrome P450 enzymes. Other expression alterations observed in the arsenic-treated male mouse newborn liver included the overexpression of cdk-inhibitors and stress response genes including increased expression of metallothionein-1 and decreased expression of betaine-homocysteine methyltransferase and thioether S-methyltransferase. Thus, transplacental exposure to arsenic at a hepatocarcinogenic dose induces alterations in DNA methylation and a complex set of aberrant gene expressions in the newborn liver, a target of arsenic carcinogenesis.",
Arsenic,710919,"Evaluation of the serum catalase and myeloperoxidase activities in chronic arsenic-exposed individuals and concomitant cytogenetic damage Abstract: Chronic arsenic exposure through contaminated drinking water is a major environmental health issue. Chronic arsenic exposure is known to exert its toxic effects by a variety of mechanisms, of which generation of reactive oxygen species (ROS) is one of the most important. A high level of ROS, in turn, leads to DNA damage that might ultimately culminate in cancer. In order to keep the level of ROS in balance, an array of enzymes is present, of which catalase (CAT) and myeloperoxidase (MPO) are important members. Hence, in this study, we determined the activities of these two enzymes in the sera and chromosomal aberrations (CA) in peripheral blood lymphocytes in individuals exposed and unexposed to arsenic in drinking water. Arsenic in drinking water and in urine was used as a measure of exposure. Our results show that individuals chronically exposed to arsenic have significantly higher CAT and MPO activities and higher incidence of CA. We found moderate positive correlations between CAT and MPO activities, induction of CA and arsenic in urine and water. These results indicate that chronic arsenic exposure causes higher CAT and MPO activities in serum that correlates with induction of genetic damage. We conclude that the serum levels of these enzymes might be used as biomarkers of early arsenic exposure induced disease much before the classical dermatological symptoms of arsenicosis begin to appear.",
Arsenic,1346401,"Speciation of arsenic metabolites in the free-living mouse Mus spretus from Doñana National Park used as a bio-indicator for environmental pollution monitoring Abstract: A speciation approach based on orthogonal chromatographic systems coupled to inductively coupled plasma mass spectrometry (ICP-MS) was used to characterise the biological response of free-living mice Mus spretus to environmental pollution caused by arsenic in different areas of the Doñana National Park (south-west Spain). The relative presence of inorganic and organic forms of arsenic was studied in cytosolic extracts from high metabolic activity organs of Mus spretus mice: kidneys, liver, and brain. An instrumental coupling of size-exclusion chromatography with UV and collision/reaction cell-ICP-MS detectors (SEC-UV-ICP-ORC-MS) both in analytical and preparative scale was used for this purpose. The results showed the presence of low molecular mass (LMM) molecules linked to arsenic in these tissues especially in the kidneys, where the presence of these arsenic metabolites was higher. On the other hand, the presence of these arsenicals varied from one area to the other, which can be related to a different occurrence of contaminants. These low molecular mass fractions were collected by preparative SEC chromatography for later study with ion exchange chromatography and detection by ICP-ORC-MS, using both anionic and cationic columns. The results showed the higher presence of MMA and DMA in kidneys of mice caught in contaminated areas and the existence of small amounts of unidentified arsenicals when cation-exchange chromatography was used, which could be related to the presence of dimethylarsinoylethanol (DMAE), thioarsenic species, or arsenocholine (AsC).",
Arsenic,1798801,"Structural Incorporation of As(5+) into hematite Abstract: Hematite (?-Fe2O3) is one of the most common iron oxides and a sink for the toxic metalloid arsenic. Arsenic can be immobilized by adsorption to the hematite surface; however, the incorporation of As in hematite was never seriously considered. In our study we present evidence that, besides adsorption, the incorporation of As into the hematite crystals can be of great relevance for As immobilization. With the coupling of nanoresolution techniques and X-ray absorption spectroscopy the presence of As (up to 1.9 wt %) within the hematite crystals could be demonstrated. The incorporated As(5+) displays a short-range order similar to angelellite-like clusters, epitaxially intergrown with hematite. Angelellite (Fe4As2O11), a triclinic iron arsenate with structural relations to hematite, can epitaxially intergrow along the (210) plane with the (0001) plane of hematite. This structural composite of hematite and angelellite-like clusters represents a new immobilization mechanism and potentially long-lasting storage facility for As(5+) by iron oxides.",
Arsenic,1347285,"Mechanisms of arsenic toxicity in vascular development Abstract: Arsenic is an abundant toxin in ground water and soil around areas with extractive industries. Exposure to arsenic is linked to several developmental defects in the nervous system and limbs, pregnancy complications and miscarriage. Vascular defects are often the underlying basis for limbs deformations and developmental anomalies in other systems and vascular abnormalities often form the basis for placentation defects linked to miscarriage. The overall goal of this project was to define the developmental mechanisms for how arsenic exposure causes developmental defects and miscarriage, and to characterize the molecular mechanisms for arsenic mediated alteration of endothelial cell physiology. We hypothesize that arsenite toxicity causes defects in vascular development, predisposing the embryo to other developmental anomalies and miscarriage. The aims are: 1. Determine how arsenite exposure affects angiogenesis in vitro. Cultured bovine aortic endothelial (BAE) cells on Matrigel were exposed to 0, 10 um, 20 um, 50 um, 100 um arsenite for 7 days. The data suggest that increasing concentrations of arsenite inhibits angiogenesis in vitro. 2. Characterize the effects of arsenite exposure on embryonic mice and vascular development. Timed-pregnant FVB/NJ mice were exposed to 1 ppm, 75 ppm and 150 ppm arsenite in their drinking water for duration of pregnancy and until weaning (21 days). Litter size was recorded and pups were weighed weekly. The data suggest that there were no significant differences observed in either litter size or pup weight for arsenite exposures of 1 ppm. However, there were significant differences for 75 ppm exposures. Arsenite exposures of 150 ppm were toxic to pregnant females, but not control (non-pregnant) females; suggesting that pregnancy may cause increased sensitivity to arsenic exposure.",
Arsenic,1022055,"Using multivariate statistical methods to assess the groundwater quality in an arsenic-contaminated area of Southwestern Taiwan Abstract: Groundwater is a major water resource in Southwestern Taiwan; hence, long-term monitoring of water quality is essential. The study aims to assess the hydrochemical characteristics of water in the arsenic-contaminated aquifers of Choushui River alluvial fan and Chianan Plain, Taiwan using multivariate statistical methods, namely, factor analysis (FA), cluster analysis (CA), and discriminant analysis (DA). Factor analysis is applied to reveal the processes controlling the hydrochemistry of groundwater. Cluster analysis is applied to spatially categorize the collected water samples based on the water quality. Discriminant analysis is then applied to elucidate key parameters associated with the occurrence of elevated As concentration (&gt;10 ?g L(-1)) in groundwater. Major water types are characterized as Na-Ca-Cl and Na-Mg-Cl in the Choushui River alluvial fan and Chianan Plain, respectively. Inorganic species of arsenic (As), particularly As(III), prevail in these two groundwater catchments, and their levels are higher in the Chianan Plain than in the Choushui River alluvial fan. Through FA, three factors, namely, the degree of salination, As reduction, and iron (Fe) reduction, are determined and denoted irrespective of some differences between the factorial compositions. Spatial distribution patterns of factors As reduction and Fe reduction imply that the redox zonation is delineated by As- and Fe-dominance zones separately. The results of CA demonstrate that three main groups can be properly explained by the factors extracted via FA. Three- (Fe(2+), Fe(3+), and NH (4) (+) ) and four-parameters (Fe(2+), Fe(3+), NH (4) (+) , and Ca(2+)) derived from discriminant analysis for Choushui River alluvial fan and Chianan Plain are elucidated as key parameters affecting the distribution of As-contained groundwater. The analytical results indicate that the reductive dissolution of Fe minerals is prerequisite for the mobilization of As, whereas the shift of redox condition from Fe- to As-reducing leads to the accumulation of dissolved As in this area.",
Arsenic,527748,"Toxicity and biouptake of lead and arsenic by Daphnia pulex Abstract: Acute and chronic toxicity studies were conducted on Daphnia pulex using synthetic lead and arsenic water samples. For acute studies, solutions with 0.25, 0.5, 1.0, 2.0, 5.0 mg/L lead and arsenic along with a control were used. The chronic studies were conducted for 21 days using 0.25, 0.5, 1.0 mg/L lead and arsenic solutions along with a control. Results indicated that the LC50 (48 hour) was 4.0 and 3.4 mg/L for lead and arsenic, respectively. Results from chronic studies suggest that the exposure to lead solutions significantly (P < 0.05) impaired the reproduction rates of Daphnia at the 1 mg/L concentration. However, the reproduction rates were enhanced at low concentrations of arsenic (up to 0.5 mg/L). A second chronic study was conducted to confirm this finding. Results from the second study indicated that lead exhibited significantly higher (P < 0.05) toxicity at 0.5 mg/L concentration, while reproduction rates in all concentrations of arsenic solutions were not significantly different from the controls. Metal analysis on exposed Daphnia, following nitric acid digestion procedures, indicated that Daphnia bio-accumulated 75.3 - 97.2% of the lead added to the experimental containers. This high lead biouptake coupled with the fast growth, high reproduction rates, and short life cycle all suggest that a Daphnia-based remediation (growth and partial harvest) may a viable treatment alternative that is worth considering. However, further field studies have to be conducted to verify this alternative. Biouptake or sequestration by Daphnia of arsenic at all tested concentrations was negligible, thereby, suggesting selective uptake or sequestration by daphnia under the tested pH and temperature conditions.",
Arsenic,628361,"The diabetogenic effects of the combination of humic acid and arsenic: In vitro and in vivo studies Abstract: Black foot disease (BFD) is a peripheral arterial occlusive disease found among the inhabitants of the southwest coast of Taiwan. Moreover, within the BFD-endemic areas, diabetes mellitus occur at significantly higher rates than in other areas of Taiwan. A high concentration of humic acid (HA), and arsenic (As) are present in the artesian well water from BFD-endemic area. The aim of this paper is to study the diabetogenic effect of the combination of HA and AS. Treatment of HIT-T15 cells with HA, As, or both of them resulted loss of cell viability, apoptosis, depletion of ATP, increment of oxidative stress, activation of caspase 3, and dysfunction of insulin secretion. In addition, the plasma insulin of ICR mice, which were exposed to HA and As in drinking water for 12 weeks, was decreased in the 5, 7, and 12 weeks, and increased at early stage of exposure (3 weeks). The results reported herein reveal that HA and As exert HIT-T15 cell dysfunction and inhibited insulin secretive effects. In addition, the sub-acute peri-pancreatitis and islet damage caused by the infiltration of inflammatory cells after exposure of HA and As in drinking water for 5 weeks. Our study has important implications in the diabetogenic effect of the HA and AS which may be mediated by ROS and further information of the toxicity mechanisms will provide under our progressive studies.",
Arsenic,1366460,"The proximal promoter region of the human heme oxygenase gene contains elements involved in stimulation of transcriptional activity by a variety of agents including oxidants Abstract: The rate of transcription of the heme oxygenase gene is enhanced by a variety of agents including oxidants such as hydrogen peroxide and UVA (320-380 nm) radiation and the sulfhydryl reagent, sodium arsenite. To further analyze the inducible response, we have isolated genomic clones of the human heme oxygenase gene. A 1.44 kb fragment corresponding to a region extending from 1416 bp upstream of the mRNA cap site to 24 bp into the 5' untranslated region of the mRNA has been further subcloned and sequenced and used as the basis for the construction of recombinant CAT transient expression vectors. By deleting large portions of this fragment, we have established that elements within 121 bp of sequence immediately upstream of the mRNA cap site respond to various agents (sodium arsenite, hydrogen peroxide, hemin, cadmium chloride and 12-O-tetradecanoyl-phorbol-13-acetate) to give a 3- to 5-fold enhancement in transient expression of the reporter gene. Under the assay conditions employed, induction can only be detected when a SV40 enhancer element is present upstream of the promoter sequence. However, control experiments show that the SV40 sequences serve to amplify the response and are not directly involved in the induction itself. Only a small induction occurs when the entire 1.44 kb fragment is present. The results are consistent with the possibility that additional inducible enhancer elements lie outside of the sequence under study and that a silencer or negative regulatory element occurs upstream of the mRNA cap site within the 1.44 kb fragment.",
Arsenic,1173147,"Arsenic as a developmental toxicant: Low dose exposure in utero induces aberrant gene expression in the embryonic lung Abstract: The human health effects of low dose arsenic exposure in the drinking water remain controversial. The adult lung is a target organ for arsenic toxicity, however, the molecular effects of maternal arsenic exposure on the developing lung are poorly understood. We hypothesize that in utero exposure to inorganic arsenic causes altered gene expression in the lung, leading to molecular and functional changes. We exposed pregnant Sprague-Dawley rats to 500 ppb arsenic in the drinking water, in the form of sodium arsenite or sodium arsenate, from conception to embryonic day eighteen. Subtractive hybridizations of embryonic lung cDNA from control and treated day 18 embryos yielded numerous differentially expressed cDNA clones. We have sequenced 352 differentially expressed cDNA clones from these subtractive hybridizations and have spotted them on a custom cDNA microarray. Using a rat alveolar type II cell line exposed to arsenic as a model for lung gene expression effects, we have carried out a dose and time-response study of subacute, low dose arsenic exposure (10, 50, 100 and 500 ppb for 1, 7 and 14 days). Using these samples for cDNA microarray hybridizations, we have profiled gene expression changes induced by arsenic exposure. Using both subtractive hybridization and cDNA microarray, we have found differential expression of genes involved in branching morphogenesis and in formation of the extracellular matrix and cytoskeleton, thus implicating arsenic as a toxicant affecting structure and function in the developing lung.",
Arsenic,1794796,"[Geochemical behavior of mine tailings and waste rock at the abandoned Cu-Mo-W Azegour mine (Occidental High Atlas, Morocco)] Abstract: [The abandoned Azegour mine is located in the High Atlas Mountains of Marrakesh (Morocco), and was mined for Cu, Mo, and W. About 850,000 t of waste rocks and tailings were deposited on the surface and have been exposed to weathering for 40 years. The remaining acid-producing potential (AP), acid-neutralizing potential, and geochemical behavior of the Azegour Cu-and Mo-rich tailings were investigated. The tailings were found to contain 9.6–19 wt% sulfur, mostly as sulfate (gypsum, anhydrite, and jarosite) while the waste rocks contain less (1.25–6.58 wt%) sulfur. The waste rocks and tailings contain 0.21–9.24 wt% Mo and 0.003–2.78 wt% Cu. The gangue is mostly composed of quartz, talc, chlorite, pyrophyllite, actonolite, clinoptilolite, and alusite. Lead, zinc, cobalt, arsenic, titanium, and nickel are also present. The calcium, which is mainly expressed as calcite, gypsum, scheelite, and powellite, is present at higher concentrations in the waste rocks (18–22 wt% Ca) than in the tailings (4.7–8.6 wt% Ca). Static ABA determinations showed that the Azegour mine wastes still have high AP, 38–205 kg CaCO3/t in the waste rocks and 46–387.7 kg CaCO3/t in the tailings. This was confirmed in weathering cell tests, where the Azegour tailings leachate had a pH range of 1.98–3.19 and high concentrations of SO4 (468–45,400 mg/L), Ca (230–675 mg/L), Fe (3–55,900 mg/L), Mn (0.1–1,430 mg/L), and Cu (2.3–9,000 mg/L). The Mo concentrations were high (35 mg/L) during the two first weeks of kinetics tests; W concentrations were below the 0.005 mg/L detection limit.]",
Arsenic,1331137,"Arsenic determination in pharmaceutical grade barium sulfate using direct solid sampling electrothermal atomic absorption spectrometry Abstract: A method for arsenic determination in pharmaceutical grade BaSO4 by solid sampling electrothermal atomic absorption spectrometry (SoS-ET AAS) is described. Two background (BG) correction systems, deuterium and Zeeman-effect (Z), were evaluated. Background was decreased by using hydrogen combined with Pd. Accurate and precise results were obtained using Z-SoS-ET AAS. Relative standard deviation using Z-SoS-ET AAS was lower than 9.5%. Limit of detection was 0.005 ?g g-1 and characteristic mass was 25.4 pg. Results were also compared with those obtained using the preparation method suggested by European Pharmacopoeia for BaSO4 followed by determination using inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry. Results were around 20% lower than results obtained using the proposed method. Some advantages as simplicity, higher sample throughput were found when compared with the official method currently described in pharmacopoeia.",
Arsenic,2088495,"Removal of groundwater arsenic using a household filter with iron spikes and stainless steel Abstract: Arsenic (As) in groundwater for domestic use poses a worldwide threat to public health, most notably in rural areas. The aims of this study were: first, determine groundwater composition in a mining area in central Mexico (Huautla); second, assess As exposure through human groundwater consumption and; third, develop and test a household filter to obtain drinking water for these rural communities. From the 17th century through the 1990s, mines in the area produced Ag-galena and sphalerite from volcanic rock. Groundwater flooded the mines when they were abandoned due to low silver prices. Local households now use the water to meet domestic needs. Water from the mines was found to have high As content (0.04-0.26 mg L(-1)) and Fe, Mn, Pb and Cd were also above Mexican drinking water standards and WHO guidelines. All the population in the Huautla community was exposed to the metalloid through water used in food preparation. The best As removal was obtained with a filter using oxidized commercial fiber (HCl 2N as oxidant). Concentrations in the effluent were below Mexican drinking water standards (0.025 mg As L(-1) water) during the 105-day (2520 h) filter operation, with a maximum As removal efficiency of 95.4%. The household filter was simple, low-cost and may be very attractive for As removal in rural areas in developing countries.",
Arsenic,1032141,"Aging of vitreous arsenic-selenium photoconductors Abstract: Vitreous arsenic-selenium photoconductors have been observed to age with resultant decreases in spectral sensitivity, dark discharge rate, and residual potential. The first two changes are attributed to surface oxidation of arsenic and the residual potential decrease to a bulk phenomenon. Vitreous selenium photoconductors also exhibit a decrease in dark discharge rate while aging. Removal of the surface layer of an aged As-Se film restores the dark discharge rate and spectral sensitivity to virgin values. Various techniques have demonstrated a change in surface morphology while aging. The effects of atmosphere and temperature on the rate and extent of aging support the surface oxidation model.",
Arsenic,627431,"Cancer incidence and high environmental arsenic concentrations in rural populations: Results of an ecological study Abstract: Geographical areas of rural Victoria, Australia, with surface soil inorganic arsenic concentrations of >100 mg/kg and/or drinking water arsenic concentrations >0.01 mg/litre were selected and the relationship with cancer incidence was investigated. Standardized incidence rates (SIRs) for cancer were generated for 22 areas during 1982-91 using Victorian Cancer Registry data and Victorian cancer rates as a baseline. SIRs were also generated for combined areas according to environmental exposure type (whether an area had high soil and/or high water arsenic concentrations). The SIRs for both males and females for the combined 22 areas were increased for all cancers 1.06 (95% confidence interval, CI; 1.03-1.09), prostate cancer 1.14 (1.05-1.23), kidney cancer 1.16 (0.98-1.37), melanoma 1.36 (1.24-1.48), chronic myeloid leukaemia 1.54 (1.13-2.10) and breast cancer in females 1.10 (1.03-1.18). When stratifying into exposure categories, the SIR for prostate cancer was significant at 1.20 (1.06-1.36) for the high soil/high water category only. No significant dose-response relationship between drinking water and individual cancers was observed. It is concluded that of the cancers associated with environmental arsenic exposure, only prostate cancer incidence was significantly elevated in this study. This result was likely confounded by a number of factors and was limited by low power and exposure misclassification.",
Arsenic,1354620,Mineralogical attenuation for metallic remediation in a passive system for mine water treatment Abstract: ,
Arsenic,1677608,"Functional evaluation of Asp76, 84, 102 and 150 in human arsenic(III) methyltransferase (hAS3MT) interacting with S-adenosylmethionine Abstract: We prepared eight mutants (D76P, D76N, D84P, D84N, D102P, D102N, D150P and D150N) to investigate the functions of residues Asp76, 84, 102 and 150 in human arsenic(III) methyltransferase (hAS3MT) interacting with the S-adenosylmethionine (SAM)-binding. The affinity of all the mutants for SAM were weakened. All the mutants except for D150N completely lost their methylation activities. Residues Asp76, 84, 102 and 150 greatly influenced hAS3MT catalytic activity via affecting SAM-binding or methyl transfer. Asp76 and 84 were located in the SAM-binding pocket, and Asp102 significantly affected SAM-binding via forming hydrogen bonds with SAM.",
Arsenic,1020462,"Treatment of arsenical keratosis and Bowen's disease with acitretin Abstract: <strong>BACKGROUND: </strong>Long-term exposure to arsenic is associated with the development of arsenical keratosis, Bowen's disease, squamous cell carcinoma, and basal cell carcinoma. The efficacy of acitretin therapy was examined in two patients with cutaneous arsenical neoplasms.<br /><br /><strong>METHODS: </strong>Lipid profile, hematological and liver function tests were performed regularly during the therapy at monthly intervals.<br /><br /><strong>RESULTS: </strong>After the third month of treatment, improvement of lesions of arsenical keratosis and Bowen's disease were observed in both patients. For the first patient who received 1 mg/kg daily acitretin for 10 months nearly total clearing was obtained at the end of therapy. The second patient discontinued the treatment after a period of 5 months because of symptomatic side-effects. During therapy no new lesions and no laboratory side-effects were observed in either patient.<br /><br /><strong>CONCLUSIONS: </strong>Although these results need to be confirmed by larger, long-term trials, it appears that acitretin is effective in the treatment of Bowen's disease related with arsenic, as well as arsenical keratosis.",
Arsenic,1030924,"Induction of mucosal glutathione synthesis by arsenic Abstract: In the rat, oral administration of 1 mg/kg arsenic (as As2O3) binds rapidly to mucosal glutathione such that effective glutathione concentration is reduced. In response to the binding of arsenic to glutathione, de novo synthesis of glutathione occurs in the mucosal cell, resulting in twice the normal concentrations of glutathione within 3 h. This finding may explain acquired tolerance to arsenic, as well as the protective effect of arsenic against selenium toxicity.",
Arsenic,1337505,"An arsenic-contaminated field trial to assess the uptake and translocation of arsenic by genotypes of rice Abstract: Compared to other cereals, rice has particular strong As accumulation. Therefore, it is very important to understand As uptake and translocation among different genotypes. A field study in Chenzhou city, Hunan province of China, was employed to evaluate the effect of arsenic-contaminated soil on uptake and distribution in 34 genotypes of rice (including unpolished rice, husk, shoot, and root). The soil As concentrations ranged from 52.49 to 83.86 mg kg(-1), with mean As concentration 64.44 mg kg(-1). The mean As concentrations in rice plant tissues were different among the 34 rice genotypes. The highest As concentrations were accumulated in rice root (196.27-385.98 mg kg(-1) dry weight), while the lowest was in unpolished rice (0.31-0.52 mg kg(-1) dry weight). The distribution of As in rice tissue and paddy soil are as follows root ? soil &gt; shoot &gt; husk &gt; unpolished rice. The ranges of concentrations of inorganic As in all of unpolished rice were from 0.26 to 0.52 mg kg(-1) dry weight. In particular, the percentage of inorganic As in the total As was more than 67 %, indicating that the inorganic As was the predominant species in unpolished rice. The daily dietary intakes of inorganic As in unpolished rice ranged from 0.10 to 0.21 mg for an adult, and from 0.075 to 0.15 mg for a child. Comparison with tolerable daily intakes established by FAO/WHO, inorganic As in most of unpolished rice samples exceeded the recommended intake values. The 34 genotypes of rice were classified into four clusters using a criteria value of rescaled distance between 5 and 10. Among the 34 genotypes, the genotypes II you 416 (II416) with the lowest enrichment of As and the lowest daily dietary intakes of inorganic As could be selected as the main cultivar in As-contaminated field.",
Arsenic,786123,"Geno- and immunotoxic effects on populations living near a mine: A case study of Panasqueira mine in Portugal Abstract: Mining industry is a vital economic sector for many countries but it is also one of the most hazardous activities, both occupationally and environmentally. Existing studies point to several adverse effects on communities' health living near mines, effects such as mesothelioma and respiratory illnesses. Results achieved in a geochemical sampling campaign undertaken in the vicinity of São Francisco de Assis village showed an anomalous distribution of some heavy metals in soils and waters. To evaluate the effects of mining activities on human health produced by these conditions, a group of 28 individuals from São Francisco de Assis village was examined for some biological endpoints. A nonexposed group (30 individuals) with the same demographic characteristics without exposure to genotoxic compounds was also studied and data obtained from both groups compared. Results of the T-cell receptor mutation assay and micronucleus (MN) test showed significant increases in the frequencies of both mutations and MN in exposed subjects compared to controls. Data obtained in the analysis of the different lymphocyte subsets demonstrated significant decreases in percentages of CD3+ and CD4+ cells, and a significant increase in percentage of CD16/56+ cells, in exposed individuals. The results of the present study indicate an elevated risk of human environmental contamination resulting from mining activities, emphasizing the need to implement preventive measures, remediation, and rehabilitation plans. This would lead to a reduction in cancer risk not only for this particular population but for all populations exposed under similar conditions.",
Arsenic,1325662,"Dietary exposure to inorganic arsenic of the Hong Kong population: Results of the first Hong Kong Total Diet Study Abstract: Inorganic arsenic, a human carcinogen, can be found in the environment and food. In the first Hong Kong Total Diet Study, the dietary exposure of the Hong Kong people, including various age-gender subgroups, to inorganic arsenic was estimated for assessing the associated health risk. Food samples, which represented the Hong Kong people's diet, were collected and prepared &quot;as consumed&quot; for analysis. Concentrations of inorganic arsenic, as sum of arsenite (As(III)) and arsenate (As(V)) were determined in 600 composite samples by using inductively coupled plasma mass spectrometry. The dietary exposures were estimated by combining the analytical results with the local food consumption data of the adult population. The mean and 95th percentile of inorganic arsenic exposures of the Hong Kong people were 0.22 and 0.38?g/kg body weight (bw)/day, respectively. Among the 12 age-gender subgroups, the respective exposures ranged from 0.19 to 0.26?g/kg bw/day and from 0.33 to 0.46?g/kg bw/day. The main food category that contributed inorganic arsenic was &quot;cereals and their products&quot; (53.5% of the total exposure), particularly rice. Having considered the carcinogenic risk of inorganic arsenic to humans, it is suggested that efforts should be made to reduce the inorganic arsenic exposure of the Hong Kong population.",
Arsenic,1033227,"Intakes of copper, zinc, cadmium, tin, iron, nickel and arsenic in a population exposed to lead from water Abstract: Adult diets obtained from a population in Ayr, Scotland, U.K., known to be exposed to lead from water were analysed for arsenic, cadmium, copper, iron, nickel, tin and zinc to assess the intake of these elements. With few exceptions, the concentration of each element varied little from diet to diet, and therefore the range of intakes varied only in proportion to the weights of the diets. With the exception of nickel, the difference between the observed average dietary intakes of the metals studied and those expected on the basis of a nationwide Total Diet Study is largely accounted for on the basis of the differences between the weights of the duplicate diet and the weight for the Total Diet Study.",
Arsenic,1509328,"Arsenite Oxidation Using Biogenic Manganese Oxides Produced by a Deep-Sea Manganese-Oxidizing Bacterium, Marinobacter sp MnI7-9 Abstract: ",
Arsenic,2149111,"Total arsenic in raw and boiled portions of Norway lobster (Nephrops norvegicus) from the central Adriatic Sea Abstract: The distribution of total arsenic in different portions of Norway lobster (Nephrops norvegicus L, Crustacea) was studied both in fresh samples and after a boiling process. All individuals (n = 80) were selected of medium standard commercial size (13-15 cm). The highest mean concentrations (26.86 ± 1.57 mg/kg wet weight) were found in the raw brown meat of the crustacean, probably due to its detoxification role, while the lowest mean values (15.97 ± 0.85 mg/kg wet weight) were in the raw exoskeleton. The raw white meat reported mean values of 16.09 ± 0.61 mg/kg w.w. The levels of arsenic contamination detected in the boiled portions showed a significant (p &lt; 0.01) decrease compared to the raw portions, as a consequence of solubilization phenomena. In fact, a large amount of arsenic from raw lobsters was transferred to the corresponding boiling broth. In the most common consumed portion, the white meat, only few losses (7.22 %) in total arsenic content were observed compared to the raw portion.",
Arsenic,1252770,"Effects of arsenic (As) exposure on the antioxidant status of gills of the zebrafish Danio rerio (Cyprinidae) Abstract: In fishes, arsenic (As) is absorbed via the gills and is capable of causing disturbance to the antioxidant system. The objective of present study was to evaluate antioxidant responses after As exposure in gills of zebrafish (Danio rerio, Cyprinidae). Fish were exposed for 48 h to three concentration of As, including the highest As concentration allowed by current Brazilian legislation (10 microg As/L). A control group was exposed to tap water (pH 8.0; 26 degrees C; 7.20 mg O(2)/L). As exposure resulted in (1) an increase (p&lt;0.05) of glutathione (GSH) levels after exposure to 10 and 100 microg As/L, (2) an increase of the glutamate cysteine ligase (GCL) activity in the same concentrations (p&lt;0.05), (3) no significant differences in terms of glutathione reductase, glutathione-S-transferase and catalase activities; (4) a significantly lower (p&lt;0.05) oxygen consumption after exposure to 100 microg As/L; (4) no differences in terms of oxygen reactive species generation and lipid peroxidation content (p&gt;0,05). In the gills, only inorganic As was detected. Overall, it can be concluded that As affected the antioxidant responses increasing GCL activity and GSH levels, even at concentration considered safe by Brazilian legislation.",
Arsenic,1579331,"Spatial and temporal trends of contaminants in mussel sampled around the Icelandic coastline Abstract: Contaminants have been determined in blue mussels (Mytilus edulis) at 11 locations around the Icelandic coastline from 1990 to 2010. The aim of the present study was to investigate if there has been a change in concentration of contaminants around the Icelandic coastline for the last two decades and if the concentrations and changes, if present, were consistent between locations. Concentrations of the persistent organic pollutants, p,p'-dichlorodiphenyldichloroethene (p,p'-DDE), hexachlorobenzene (HCB), ?-hexachlorocyclohexane (?-HCH), polychlorinated biphenyl (PCB-153) and trans-nonachlor, have decreased at most of the sampling locations in Iceland in recent years. However, an increasing trend was found at a few locations that could be explained by anthropogenic activity. The concentration levels of the persistent organics were much lower than found at the Norwegian, USA and Chinese coasts, especially levels of p,p'-DDE. The concentration of copper and selenium had a consistent pattern of change and concentration between locations over the period which showed a decreasing trend in recent years. The trace elements arsenic, cadmium, mercury and zinc showed more variation in concentration between locations, the concentration of arsenic, mercury and zinc was fairly stable over the period, whereas there were fluctuations in cadmium concentrations. The concentrations of cadmium and zinc were observed to be somewhat higher than found in mussels from Norway, USA and China but values of mercury and lead were much lower in the mussel sampled in Iceland. The higher concentrations of cadmium and zinc can be explained by the volcanic activity in Iceland but no major anthropogenic sources of trace elements are known in Iceland.",
Arsenic,2278650,"A need for determination of arsenic species at low levels in cereal-based food and infant cereals. Validation of a method by IC-ICPMS Abstract: The present study arose from the need to determine inorganic arsenic (iAs) at low levels in cereal-based food. Validated methods with a low limit of detection (LOD) are required to analyse these kinds of food. An analytical method for the determination of iAs, methylarsonic acid (MA) and dimethylarsinic acid (DMA) in cereal-based food and infant cereals is reported. The method was optimised and validated to achieve low LODs. Ion chromatography-inductively coupled plasma mass spectrometry (IC-ICPMS) was used for arsenic speciation. The main quality parameters were established. To expand the applicability of the method, different cereal products were analysed: bread, biscuits, breakfast cereals, wheat flour, corn snacks, pasta and infant cereals. The total and inorganic arsenic content of 29 cereal-based food samples ranged between 3.7-35.6 and 3.1-26.0 ?g As kg(-1), respectively. The present method could be considered a valuable tool for assessing inorganic arsenic contents in cereal-based foods.",
Arsenic,1016439,"Selenium-dependent and -independent transport of arsenic by the human multidrug resistance protein 2 (MRP2/ABCC2): Implications for the mutual detoxification of arsenic and selenium Abstract: Simultaneous exposure of lab animals to toxic doses of the human carcinogen arsenic (As) and the essential trace element selenium (Se) results in a remarkable mutual detoxification. A likely basis for this is the in vivo formation and biliary excretion of seleno-bis(S-glutathionyl) arsinium ion [(GS)(2)AsSe](-); however, the transport protein responsible for the biliary efflux of [(GS)(2)AsSe](-) has not been identified. The multidrug resistance protein 2 (MRP2/ABCC2) is an adenosine triphosphate (ATP)-binding cassette transporter expressed at the canalicular membrane of hepatocytes. Rat Mrp2 is known to excrete the As glutathione (GSH/GS-) conjugates arsenic triglutathione [As(GS)(3)] and monomethyl arsenic diglutathione [CH(3)As(GS)(2)] into bile, and in vitro studies have established As(GS)(3) as a substrate for human MRP2. In the present study, membrane vesicles prepared from human embryonic kidney (HEK293T) cells transfected with human MRP2 were used to demonstrate that MRP2 transports [(GS)(2)AsSe](-). In addition, the characteristics of MRP2 transport of As(GS)(3) and [(GS)(2)AsSe](-) were investigated. As(GS)(3) and [(GS)(2)AsSe](-) are chemically labile and have the potential to dissociate. However, arsenite (As(III)) +/- selenite (Se(IV)) transport was not detected in the absence of GSH or in the presence of the non-reducing GSH analog, ophthalmic acid, suggesting that the conjugates are the transported forms. The apparent K(m) values for [(GS)(2)AsSe](-) and As(GS)(3) were 1.7 and 4.2 microM, respectively, signifying high relative affinities. Membrane vesicles prepared from human erythrocytes, which express the MRP2-related MRP1/ABCC1, MRP4/ABCC4 and MRP5/ABCC5, transported As(GS)(3) in an MRP1- and ATP-dependent manner but did not transport [(GS)(2)AsSe](-). These results have important implications for the Se-dependent and -independent disposition of As.",
Arsenic,1377970,"Arsenite Inhibits Cell Cycle Progression Of U937 Myeloid Leukemia Cells Through Induction Of Cdc25A Degradation Abstract: Arsenic acts as a toxicant, a carcinogen and an effective chemotherapeutic in the treatment of acute promyelocytic leukemia. Its effects on humans are well-documented, but arsenic's mechanism of action is not well-understood. Arsenic has been shown to inhibit cancer cell cycle progression, but the targeted cell cycle phase has been debated. We monitored the cell cycle progression of cell cycle phase-enriched populations of U937 cells in the presence and absence of 5uM NaAsO2 and determined that arsenite inhibits cell cycle progression through each cell cycle phase. 5-Bromo-2'-deoxyuridine pulse chase experiments show that S-phase transit time is markedly increased by arsenite (15h with treatment vs. 11h without). G2/M appears to be the phase most sensitive to arsenite-induced apoptosis, but given the large percentage of S phase cells in an asynchronous population, arsenite's inhibition of S phase progression may contribute significantly to overall growth inhibition. Cell cycle progression is controlled by the activities of cyclin dependent kinases (cdks), which are in turn regulated by cyclin binding and by activating and inhibitory phosphorylations. Cdc25 dual specificity phosphatases dephosphorylate sites of inhibitory phosphorylation as the last step before cdks trigger progression into the next cell cycle phase. Treatment of U937 cells with 5uM NaAsO2 for 2h results in a dramatic decrease in protein levels of cdc25A, which controls entry into and progression through S phase by dephosphorylating Tyr15 and Thr14 on cdk2. Cdc25A is regulated by ubiquitin-dependent proteasomal degradation, triggered by its phosphorylation. A time course of concurrent treatment of cells with cycloheximide and arsenite reveals that cdc25A is degraded more quickly in arsenite-treated cells. Arsenite-dependent degradation of cdc25A could contribute to inhibition of S phase entry and progression. Studies are ongoing to establish the dependence of arsenite-induced cdc25A degradation on ubiquitination and proteasome activity and the involvement of cdc25A in arsenite-induced growth inhibition.",
Arsenic,2088484,"Gender, clamped hyperglycemia and arterial stiffness in patients with uncomplicated type 1 diabetes mellitus Abstract: Background: Diabetes mellitus (DM) reduces female gender-mediated protection against the development of renal disease possibly through effects on hyperglycemia. Women with DM also exhibit increased arterial stiffness, which may promote renal disease progression. The mechanisms responsible for increased arterial stiffness in women and the possible role of acute changes in ambient glycemia remain unknown. Methods: Blood pressure, augmentation index (AIx), pulse wave velocity (PWV) and circulating mediators of the renin angiotensin system and nitric oxide (cGMP) were measured in men (n?=?22) and women (n?=?19) with uncomplicated type 1 DM under clamped euglycemic and hyperglycemic conditions. Results: At baseline, men exhibited higher levels of angiotensin II (p?=?0.030) and lower cGMP levels (p?=?0.004), higher systolic blood pressure (124?±?2 versus 109?±?2?mmHg, p?<?0.0001) and pulse pressure (42?±?2 versus 58?±?2 beats per minute, p<0.0001). For arterial stiffness, radial (-8.0?±?2.6% versus +5.4?±?3.7%, p<?0.0001) and carotid AIx (-4.7?±?2.9 versus +12.5?±?3.0, p<0.0001) were lower in men versus women. In contrast, carotid-femoral PWV was similar in men and women (5.20?±?0.30 versus 5.13?±?0.17, respectively, p?=?0.853). In response to clamped hyperglycemia, systolic blood pressure increased in women (109?±?2 to 112?±?2?mmHg, p?=?0.005) but not men. Serum aldosterone increased and cGMP declined in women but not in men. Clamped hyperglycemia did not influence arterial stiffness in either group and radial and carotid AIx remained higher in women. Conclusions: Arterial stiffness is higher in women with type 1 DM. This effect is not dependent on the effects of clamped hyperglycemia or neurohormonal activation.",
Arsenic,710802,"Arsenate-induced apoptosis in murine embryonic maxillary mesenchymal cells via mitochondrial-mediated oxidative injury Abstract: Arsenic is a ubiquitous element that is a potential carcinogen and teratogen and can cause adverse developmental outcomes. Arsenic exerts its toxic effects through the generation of reactive oxygen species (ROS) that include hydrogen peroxide (H(2)O(2)), superoxide-derived hydroxyl ion, and peroxyl radicals. However, the molecular mechanisms by which arsenic induces cytotoxicity in murine embryonic maxillary mesenchymal (MEMM) cells are undefined.<br /><br /> MEMM cells in culture were treated with different concentrations of pentavalent sodium arsenate [As (V)] for 24 or 48 hr and various end points measured.<br /><br /> Treatment of MEMM cells with the pentavalent form of inorganic arsenic resulted in caspase-mediated apoptosis, accompanied by generation of ROS and disruption of mitochondrial membrane potential. Treatment with caspase inhibitors markedly blocked apoptosis. In addition, the free radical scavenger N-acetylcysteine dramatically attenuated arsenic-mediated ROS production and apoptosis, and exposure to arsenate increased Bax and decreased Bcl protein levels in MEMM cells.<br /><br /> Taken together, these findings suggest that in MEMM cells arsenate-mediated oxidative injury acts as an early and upstream initiator of the cell death cascade, triggering cytotoxicity, mitochondrial dysfunction, altered Bcl/Bax protein ratios, and activation of caspase-9.",
Arsenic,627254,"In vitro bioavailability of heavy metals in pressure-treated wood dust Abstract: Pressure treatment with chromium, copper, and arsenic (CCA) is the most prevalent method for protecting wood used in outdoor construction projects. Although these metals are tightly bound to the wood fibers and are not released under most conditions of use, we examined the bioavailability of metals in CCA pressure-treated wood dust in vitro. Cytotoxicity and metallothionein (MT) mRNA expression were examined in V79 Chinese hamster lung fibroblast cells incubated with respirable-size wood dust generated by sanding CCA-treated and untreated (control) Southern yellow pine. In colony survival studies, increased cytotoxicity (p < 0.05) occurred in V79 cells treated with CCA wood dust (351 +/- 77 microg/ml, mean +/- SE) compared with control wood dust (883 +/- 91 microg/ml). Increased cytotoxicity with CCA wood dust also occurred in an arsenic resistant subline of V79 cells, thus suggesting that arsenic was not responsible for the increased cytotoxicity. Metallothionein mRNA was significantly increased after 48 h of treatment with CCA wood dust compared with control wood dust. Incubation of CCA wood dust in cell culture media resulted in the transfer of copper, but not chromium or arsenic, into the media. Moreover, the treatment of cells with this filtered extract resulted in significantly increased metallothionein mRNA, suggesting that bioavailable copper is responsible for inducing metallothionein mRNA in V79 cells. Thus, these bioassays suggest that metals become bioavailable during in vitro culture of phagocytic V79 cells with CCA wood dust.",
Arsenic,2278341,"Adsorption of arsenic on pre-treated zeolite at different pH levels Abstract: Natural zeolites are widely used to minimise the impact of some pollutants in the environment, such as the removal of metals in various water sources as well as effluents used in the mining and metallurgical industry and in the treatment of mining acid solutions. The most common varieties of zeolites are analcime, chabazite, clinoptilolite, heroinite, ferrierite, mordenite. Researchers have studied for decades their synthesis, structure and proprieties, and as a result a large number of patents have been obtained on the preparation of different types of zeolite in conjunction with metals or metal compounds as selective adsorbents for anions and cations of water solutions. For example, iron, zirconium and magnesium hydroxide show selectivity in the adsorption of arsenic among other industrial applications of great interest. This study shows the importance of using natural pre-treated zeolites in the adsorption of arsenic in water due to the adsorption percentages that are higher than 90%, controlling the pH in the pre-treatment. Samples were treated at different pH levels, getting a better adjustment of isotherms of adsorption at pH = 9 with ZP-9.",
Arsenic,1794812,Determining the presence of arsenic in chicken products using atomic absorption spectroscopy Abstract: ,
Arsenic,1024724,"Increased hexokinase II expression in the renal glomerulus of mice in response to arsenic Abstract: Epidemiological studies link arsenic exposure to increased risks of cancers of the skin, kidney, lung, bladder and liver. Additionally, a variety of non-cancerous conditions such as diabetes mellitus, hypertension, and cardiovascular disease have been associated with chronic ingestion of low levels of arsenic. However, the biological and molecular mechanisms by which arsenic exerts its effects remain elusive. Here we report increased renal hexokinase II (HKII) expression in response to arsenic exposure both in vivo and in vitro. In our model, HKII was up-regulated in the renal glomeruli of mice exposed to low levels of arsenic (10 ppb or 50 ppb) via their drinking water for up to 21 days. Additionally, a similar effect was observed in cultured renal mesangial cells exposed to arsenic. This correlation between our in vivo and in vitro data provides further evidence for a direct link between altered renal HKII expression and arsenic exposure. Thus, our data suggest that alterations in renal HKII expression may be involved in arsenic-induced pathological conditions involving the kidney. More importantly, these results were obtained using environmentally relevant arsenic concentrations.",
Arsenic,2064272,"Arsenic-induced cancer cell phenotype in human breast epithelia is estrogen receptor-independent but involves aromatase activation Abstract: Accumulating data suggest arsenic may be an endocrine disruptor and tentatively linked to breast cancer by some studies. Therefore, we tested the effects of chronic inorganic arsenic exposure on the normal estrogen receptor (ER)-negative breast epithelial cell line, MCF-10A. Cells were chronically exposed to a low-level arsenite (500 nM) for up to 24 weeks. Markers of cancer cell phenotype and the expression of critical genes relevant to breast cancer or stem cells (SCs) were examined. After 24 weeks, chronic arsenic-exposed breast epithelial (CABE) cells showed increases in secreted MMP activity, colony formation, invasion, and proliferation rate, indicating an acquired cancer cell phenotype. These CABE cells presented with basal-like breast cancer characteristics, including ER-?, HER-2, and progesterone receptor negativity, and overexpression of K5 and p63. Putative CD44(+)/CD24(-/low) breast SCs were increased to 80 % over control in CABE cells. CABE cells also formed multilayer cell mounds, indicative of loss of contact inhibition. These mounds showed high levels of K5 and p63, indicating the potential presence of cancer stem cells (CSCs). Epithelial-to-mesenchymal transition occurred during arsenic exposure. Overexpression of aromatase, a key rate-limiting enzyme in estrogen synthesis, occurred with arsenic starting early on in exposure. Levels of 17?-estradiol increased in CABE cells and their conditioned medium. The aromatase inhibitor letrozole abolished arsenic-induced increases in 17?-estradiol production and reversed cancer cell phenotype. Thus, chronic arsenic exposure drives human breast epithelia into a cancer cell phenotype with an apparent overabundance of putative CSCs. Arsenic appears to transform breast epithelia through overexpression of aromatase, thereby activating oncogenic processes independent of ER.",
Arsenic,2345773,"Phytoprotective effect of arbuscular mycorrhizal fungi species against arsenic toxicity in tropical leguminous species Abstract: Arbuscular mycorrhizal fungi (AMF) improve the tolerance of hosting plants to arsenic (As) in contaminated soils. This work assessed the phytoprotective effect of Glomus etunicatum, Acaulospora morrowiae, Gigaspora gigantea, and Acaulospora sp. on four leguminous species (Acacia mangium, Crotalaria juncea, Enterolobium contortisiliquum, and Stizolobium aterrimum) in an As-contaminated soil from a gold mining area. AMF root colonization, biomass production, As and P accumulation, as well as arsenic translocation index (TI) from roots to shoots were measured. The AMF phytoprotective effect was assessed by the P/As ratio and the activity of plant antioxidant enzymes. The AMF colonization ranged from 24 to 28%. In general, all leguminous species had low As TI when inoculated with AMF species. Inoculation of C. juncea with Acaulospora sp. improved significantly As accumulation in roots, and decreased the activity of ascorbate peroxidase (APX) and superoxide dismutase (SOD), highlighting its phytoprotective effect and the potential use of this symbiosis for phytoremediation of As-contaminated soils. However, S. aterrimum has also shown a potential for phytoremediation irrespectively of AMF inoculation. APX was a good indicator of the phytoprotective effect against As contamination in C. juncea and A. mangium. In general P/As ratio in shoots was the best indicator of the phytoprotective effect of all AMF species in all plant species.",
Arsenic,1373324,"Efficient transcription of a Caenorhabditis elegans heat shock gene pair in mouse fibroblasts is dependent on multiple promoter elements which can function bidirectionally Abstract: A divergently transcribed pair of Caenorhabditis elegans hsp16 genes was introduced into mouse fibroblasts by stable transfection with vectors containing bovine papillomavirus plasmid maintenance sequences and a selectable gene. The hsp16 genes were transcriptionally inactive in the mouse cells under normal growth conditions and were strongly induced by heat shock or arsenite. In a cell line with 12 copies of the gene pair, there were estimated to be more than 10,000 hsp16 transcripts in each cell after 2 h of heat shock treatment. The hsp16 transcript levels were more than 100 times higher than those of a gene with a herpes simplex virus thymidine kinase gene promoter carried on the same vector. A single heat shock promoter element (HSE) could activate bidirectional transcription of the two hsp16 genes when placed between the two TATA elements, but the transcriptional efficiency was reduced 10-fold relative to that of the wild-type gene pair. Four overlapping HSEs positioned between the two TATA elements resulted in inducible bidirectional transcription at greater than wild-type levels. The number of HSEs can therefore be a major determinant of the promoter strength of heat-inducible genes in mammalian cells. Partial disruption of an alternating purine-pyrimidine sequence between the two hsp16 genes had no significant effect on their transcriptional activity.",
Arsenic,1029506,"Effect of arsenic on p53 mutation and occurrence of teratogenic salamanders: Their potential as ecological indicators for arsenic contamination Abstract: The p53 mutation in salamanders can be used as an indicator of arsenic contamination. The influence of arsenic exposure was studied on mutation of tumor suppressor gene in salamanders collected from several As-contaminated mine areas in Korea. Salamander eggs and larvae were exposed to arsenic in a toxicity test, and teratogenic salamanders found in heavy metal- and As-contaminated water from As-Bi mines were evaluated using PCR-SSCP to determine if they would be useful as an ecological indicator species. Changes in amino acids were shown to have occurred as a result of an arsenic-accumulating event that occurred after the DNA damage. In addition, both of the Hynobius leechii exposed groups were primarily affected by forms of skin damage, changes in the lateral tail/dorsal flexure and/or abnormality teratogenesis. Single-base sense mutation in codons 346 (AAG: Lys to ATG: Met), 224 (TTT: Phe to TTA: Leu), 211 (ATG: Met to AAG: Lys), 244 (TTT: Phe to TTTG: insertion), 245 (Glu GAG to Gln CAG) and 249 (TGT Cys to TGA stop) of the p53 gene were simultaneously found in mutated salamanders. Based on the results of our data illustrating the effect of arsenic exposure on the p53 mutation of salamanders in arsenic-contaminated mine areas, these mutated salamanders can be used as potential ecological indicators in the arsenic-contaminated ecosystems.",
Arsenic,1936126,"Arsenic in groundwaters of the alluvial aquifer of Bardsir plain, SE Iran Abstract: Bardsir plain is located in the central part of Kerman Province of Iran. The relative prevalence of arsenic-related cancers, the high concentration of arsenic in nearby plains, as well as the recharge of this aquifer through the mountains composed of high-sulfide volcanic rocks have been motivations of the authors to study the concentration of this element in Bardsir plain. Arsenic concentration was measured in 63 groundwater samples using inductively coupled plasma mass spectrometry method. The results were evaluated through iso-concentration maps, correlation diagrams, and multivariate statistical methods. Accordingly, the concentration of arsenic ranges from 1.3 to 464.5 ?g/l with an average value of 134.2 ?g/l. So, the groundwaters are enriched with arsenic to much higher levels than permitted for than drinking water acceptable level (10 ?g/l). The high arsenic levels in groundwaters of Bardsir plain are ascribed to joint influence of decomposition of sulfides present in mountainous volcanic rocks and the mixing with hydrothermal waters in some locations. Supposedly, the prevalence of higher than 8 pH values has enhanced the release of arsenic from Fe-hydroxides generated during sulfide weathering process.",
Arsenic,1021609,"Performance of Eleocharis macrostachya and its importance for arsenic retention in constructed wetlands Abstract: <strong>INTRODUCTION: </strong>Arsenic (As) can be removed from water via rhizofiltration using phytostabilizing plants. The aim of this study was to investigate the performance of Eleocharis macrostachya in constructed wetland prototypes, as well as the plant's arsenic mass retention and the distribution of As along the wetland flow gradient and the soil in the wetland mesocosmos.<br /><br /><strong>MATERIALS AND METHODS: </strong>Experiments were carried out in laboratory-scale wetland prototypes, two planted with E. macrostachya and one without plants. Samples of water were taken at the inlet and outlet of the wetlands during the 33-week test period. At the end of the experiment, plants and soil (silty-sand) from each prototype were divided in three equal segments (entrance, middle and exit) and analyzed for their arsenic content. Results revealed that the planted wetlands have a higher As-mass retention capacity (87-90% of the total As inflow) than prototypes without plants (27%).<br /><br /><strong>RESULTS: </strong>As mass balance in the planted wetlands revealed that 78% of the total inflowing As was retained in the soil bed. Nearly 2% was absorbed in the plant roots, 11% was flushed as outflow, and the fate of the remaining 9% is unknown. In the prototype without plants, the soil retained 16% of As mass, 72% of the arsenic was accounted for in the outflow, and 12% was considered unknown. Although E. macrostachya retained only 2% of the total arsenic mass in their roots, its presence was a determining factor for arsenic retention in the wetland soil medium.<br /><br /><strong>CONCLUSION: </strong>Hence, planted wetlands might be a suitable option for treating As-contaminated water.",
Arsenic,2278496,"Vertical distribution of bacterial populations associated with arsenic mobilization in aquifer sediments from the Hetao plain, Inner Mongolia Abstract: To understand the mechanism of arsenic mobilization from sediment to groundwater mediated by microorganism, vertical distribution of bacterial populations in aquifer sediments of the Hetao plain, Inner Mongolia was investigated by a two-step nested PCR-DGGE and 16S rRNA gene clone libraries, combined with sediment geochemistry. A borehole to 30 m depth was drilled and 11 sediment samples were collected. Lithological profile and different geochemical characteristics of sediments indicated a distinct transition of oxidizing-reducing environment along the depth of the sediment core. As(III) and Fe(II) concentrations elevated progressively from 10 m, simultaneously coupling with decrease of As(V) and Fe(III) concentrations, implying that reductive dissolution of arsenic-rich Fe(III) oxyhydroxides led to arsenic release. Results of DGGE displayed that sediment samples with higher concentrations of total arsenic and total organic carbon had lower population diversity, which suggested total arsenic concentrations were important to determine the population diversity of sediments. Bacterial communities of a sediment sample with the highest diversity and ratio of As(III) to total As were dominated by aerobic and facultative anaerobic bacteria and belonged to Alpha-, Beta-, and Gammaproteobacteria and Firmicutes group. Most of the retrieved sequences were closely related to high arsenic-resistance organisms, sulfide/thiosulfate oxidizers, denitrifiers, and aromatic hydrocarbon degraders. Thiobacillus distinctly predominated in clone library, which suggested that arsenic might be released by oxidized dissolution of sulfide minerals coupled to arsenate reduction or nitrate reduction in anaerobic condition. These data have important implications for understanding the microbially mediated arsenic mobilization in aquifers.",
Arsenic,1338649,"Joint effect of arsenic methylation profile and NNK metabolites on urothelial carcinoma Abstract: <strong>PURPOSE: </strong>Cigarette smoking interacts with the urinary arsenic profile to modify the risk of urothelial carcinoma. NNK (4-[methylnitrosamino]-1-[3-pyridyl]-1-butanone) and its metabolite NNAL (4-[methylnitrosamino]-1-[3-pyridyl]-1-butanol) are biomarkers for cigarette smoking exposure. We explored the joint effects of urinary NNK metabolites and arsenic species on urothelial carcinoma risk.<br /><br /><strong>MATERIALS AND METHODS: </strong>We recruited 137 pairs of urothelial carcinoma cases and matched healthy participants for a hospital based case-control study. Participants completed questionnaires and provided 50 ml urine samples. Urine samples were analyzed for free NNAL and NNAL-glucuronides using liquid chromatography-tandem mass spectrometry. Samples were analyzed for arsenic species using high performance liquid chromatography hydride generator atomic absorption spectrometry.<br /><br /><strong>RESULTS: </strong>Overall, subjects with high urinary total NNAL and high total arsenic had a greater urothelial carcinoma risk than those with a low total NNAL and low total arsenic. Subjects with a lower ratio of NNAL-glucuronides-to-free NNAL and higher total arsenic had a greater urothelial carcinoma risk than those with a higher NNAL-glucuronides-to-free NNAL ratio and lower total arsenic.<br /><br /><strong>CONCLUSIONS: </strong>This is the first study to our knowledge to demonstrate a significant trend of progressively increased risk of urothelial carcinoma in subjects who had none, one or both of the factors of urinary total arsenic and total NNAL or urinary total arsenic and the ratio of NNAL-glucuronides-to-free NNAL.",
Arsenic,1579239,"Exposure to food contaminants during pregnancy Abstract: During pregnancy, the fetus is exposed to contaminants from its mother's diet. This work provides an assessment of the dietary exposure of pregnant women to inorganic contaminants (aluminum, mercury, lead, inorganic arsenic, cobalt), polychlorodibenzodioxins, polychlorodibenzofurans, dioxin-like and non-dioxin-like polychlorobiphenyls (DL-PCBs, NDL-PCBs), polybromodiphenyl ethers (PBDEs), perfluoroalkyl acids, mycotoxins (zearalenone, patulin, trichothecenes), and heat-generated compounds (acrylamide and polycyclic aromatic hydrocarbons). Consumption data of 2002 pregnant women aged 18 to 45 from the EDEN cohort study were combined with contamination data from the second French total diet study to assess the exposure before pregnancy (n=1861) and during the third trimester of pregnancy (n=1775). Exposure was also assessed considering the season during which the third trimester of pregnancy occurred. Significant changes in consumptions during pregnancy and between seasons were associated with differences in exposures for some substances. Some contaminant exposures appeared to be of health concern. Margins of exposure to acrylamide (635 to 1094 for mean), inorganic arsenic, lead, and BDE-99 (?100) were too low to exclude all risks. For NDL-PCBs, T-2 and HT-2 toxins, and deoxynivalenol, significant exceedings of toxicological reference values were found before pregnancy, but there was no significant exceeding in the third trimester.",
Arsenic,1024499,"Stillbirth in rural Bangladesh: Arsenic exposure and other etiological factors: A report from Gonoshasthaya Kendra Abstract: <strong>OBJECTIVE: </strong>To use data collected by Gonoshasthaya Kendra, a large nongovernmental organization providing health care to some 600 villages, to describe the epidemiological pattern of stillbirth and any additional contribution made by arsenic contamination of hand-pump wells in Bangladesh.<br /><br /><strong>METHODS: </strong>Completed pregnancies and outcomes (n = 30 984) for two calendar years, together with existing data on 26 socioeconomic and health factors were selected for study. The health care in these villages was administered from 16 geographical centres; information on the average arsenic concentration in each centre was obtained from the National Hydrochemical Survey. After univariate analysis, a multivariate, multilevel, logistic model for stillbirth was developed. The additional effect of arsenic was calculated having adjusted for all potential confounders thus identified.<br /><br /><strong>FINDINGS: </strong>The overall stillbirth rate was 3.4% (1056/30 984) and increased with estimated arsenic concentration (2.96% at &lt; 10 microg/l; 3.79% at 10 microg/l to &lt; 50 microg/l; 4.43% at &gt; 50 microg/l). Having adjusted for 17 socioeconomic and health factors, the odds ratios estimated for arsenic (with &lt; 10 microg/l as reference) remained raised: 1.23 (95% confidence interval, CI: 0.87A1.74) at 10 microg/l to &lt; 50 microg/l and 1.80 (95% CI: 1.14A2.86) at 50 microg/l or greater.<br /><br /><strong>CONCLUSION: </strong>A increased risk of stillbirth is associated with arsenic contamination. This risk, substantial enough to be detected by an ecological approach and not readily attributable to unmeasured confounding, is essentially preventable and all efforts must be made to protect women at high risk.",
Arsenic,628628,"Low level, long-term inorganic arsenite exposure causes generalized resistance to apoptosis in cultured human keratinocytes: Potential role in skin co-carcinogenesis Abstract: Inorganic arsenic is a human carcinogen that targets the skin. Carcinogenesis is a multistep process in which acquired apoptotic resistance is a common event and prior work in non-skin cells shows acquired resistance to apoptosis occurs with chronic arsenite exposure. In the present study, when HaCaT cells, an immortalized, non-tumorigenic human keratinocyte cell line, were continuously exposed to low-level inorganic arsenite (as sodium arsenite; 100 nM) for 28 weeks, the cells acquired a generalized resistance to apoptosis. This included resistance to apoptosis induced by acute high concentrations of arsenite, ultraviolet A (UVA) irradiation, and several chemotherapeutic compounds (cisplatin, etoposide and doxorubicin). These arsenite-tolerant (As-TL) cells showed similar levels of UVA-induced reactive oxygen species (ROS) and oxidative DNA damage when compared to passage match control cells. Because cellular apoptosis is dependent on the balance between proapoptotic and survival pathways, the roles of protein kinase B (PKB), a key antiapoptotic molecule, in this acquired apoptotic resistance were investigated. Stimulation of apoptosis markedly decreased nuclear phosphorylated PKB (P-PKB) levels in control cells, but As-TL cells showed greatly increased stability of nuclear P-PKB. Pretreatment of the As-TL cells with LY294002 or Wortmannin, which specifically inhibit PKB phosphorylation, completely blocked apoptotic resistance in As-TL cells, indicating acquired apoptotic resistance is associated with increased stability of nuclear P-PKB. Because arsenic and UV irradiation are co-carcinogenic in mouse skin, resistance to UV-induced apoptosis in As-TL cells may allow UV-damaged cells to escape normal cell population controls and initiate the carcinogenic cascade. The observation that As-TL cells show no lessening of UV-induced genotoxicity supports this possibility.",
Arsenic,62147,"Peripheral neuropathy caused by arsenical intoxication; a study of 41 cases with observations on the effects of BAL (2,3, dimercapto-propanol) Abstract: ",
Arsenic,1027679,"Sodium arsenite induces chromosome endoreduplication and inhibits protein phosphatase activity in human fibroblasts Abstract: Arsenic, strongly associated with increased risks of human cancers, is a potent clastogen in a variety of mammalian cell systems. The effect of sodium arsenite (a trivalent arsenic compound) on chromatid separation was studied in human skin fibroblasts (HFW). Human fibroblasts were arrested in S phase by the aid of serum starvation and aphidicolin blocking and then these cells were allowed to synchronously progress into G2 phase. Treatment of the G2-enriched HFW cells with sodium arsenite (0-200 microM) resulted in arrest of cells in the G2 phase, interference with mitotic division, inhibition of spindle assembly, and induction of chromosome endoreduplication in their second mitosis. Sodium arsenite treatment also inhibited the activities of serine/threonine protein phosphatases and enhanced phosphorylation levels of a small heat shock protein (HSP27). These results suggest that sodium arsenite may mimic okadaic acid to induce chromosome endoreduplication through its inhibitory effect on protein phosphatase activity.",
Arsenic,1348277,"Positive correlation between mammalian life span and cellular resistance to stress Abstract: Identifying the mechanisms determining species-specific life spans is a central challenge in understanding the biology of aging. Cellular stresses produce damage, that may accumulate and cause aging. Evolution theory predicts that long-lived species secure their longevity through investment in a more durable soma, including enhanced cellular resistance to stress. To investigate whether cells from long-lived species have better mechanisms to cope with oxidative and non-oxidative stress, we compared cellular resistance of primary skin fibroblasts from eight mammalian species with a range of life spans. Cell survival was measured by the thymidine incorporation assay following stresses induced by paraquat, hydrogen peroxide, tert-butyl hydroperoxide, sodium arsenite and alkaline pH (sodium hydroxide). Significant positive correlations between cell LD90 and maximum life span were found for all these stresses. Similar results were obtained when cell survival was measured by the MTT assay, and when lymphocytes from different species were compared. Cellular resistance to a variety of oxidative and non-oxidative stresses was positively correlated with mammalian longevity. Our results support the concept that the gene network regulating the cellular response to stress is functionally important in aging and longevity.",
Arsenic,1351758,"Stress-induced inhibition of the NF-kappa B signaling pathway results from the insolubilization of the I kappa B kinase complex following its dissociation from heat shock protein 90 Abstract: Activation of the stress response attenuates proinflammatory responses by suppressing cytokine-stimulated activation of the NF-kappaB signaling pathway. In this study, we show that the activation of the cellular stress response, either by heat shock treatment or after exposure to sodium arsenite, leads to a transient inhibition of IkappaBalpha phosphorylation. Inhibition of IkappaBalpha phosphorylation after stress was associated with the detergent insolubilization of the upstream kinases, IkappaB kinase alpha (IKKalpha) and IkappaB kinase beta, components involved in IkappaBalpha phosphorylation. Pretreatment of cells with glycerol, a chemical chaperone that reduces the extent of stress-induced protein denaturation, reduced the stress-dependent detergent insolubility of the IKK complex and restored the cytokine-stimulated phosphorylation of IkappaB. The stress-dependent insolubility of the IKK complex appeared reversible; as the cells recovered from the heat shock treatment, the IKK complex reappeared within the soluble fraction of cells and was again capable of mediating the phosphorylation of IkappaBalpha in response to added cytokines. Treatment of cells with geldanamycin, an inhibitor of heat shock protein 90 (Hsp90) function, also resulted in IKK detergent insolubility and proteasome-mediated degradation of the IKK complex. Furthermore, while IKKalpha coprecipitated with Hsp90 in control cells, coprecipitation of the two proteins was greatly reduced in those cells early after stress or following exposure to geldanamycin. Stress-induced transient insolubilization of the IkappaB kinase complex following its dissociation from Hsp90 represents a novel mechanism by which the activation of the stress response inhibits the NF-kappaB signaling pathway in response to proinflammatory stimuli.",
Arsenic,1015700,"Spatial modeling of households' knowledge about arsenic pollution in Bangladesh Abstract: Arsenic in drinking water is an important public health issue in Bangladesh, which is affected by households' knowledge about arsenic threats from their drinking water. In this study, spatial statistical models were used to investigate the determinants and spatial dependence of households' knowledge about arsenic risk. The binary join matrix/binary contiguity matrix and inverse distance spatial weight matrix techniques are used to capture spatial dependence in the data. This analysis extends the spatial model by allowing spatial dependence to vary across divisions and regions. A positive spatial correlation was found in households' knowledge across neighboring districts at district, divisional and regional levels, but the strength of this spatial correlation varies considerably by spatial weight. Literacy rate, daily wage rate of agricultural labor, arsenic status, and percentage of red mark tube well usage in districts were found to contribute positively and significantly to households' knowledge. These findings have policy implications both at regional and national levels in mitigating the present arsenic crisis and to ensure arsenic-free water in Bangladesh.",
Arsenic,1070147,Survey of selected activities relevant to exposures to soils Abstract: ,
Arsenic,2345602,"Feasibility of biochar manufactured from organic wastes on the stabilization of heavy metals in a metal smelter contaminated soil Abstract: The main objectives of the current study were to evaluate the potential effects of biochar derived from sugar cane bagasse (SC-BC) and orange peel (OP-BC) on improving the physicochemical properties of a metal smelter contaminated soil, and determining its potentiality for stabilizing Pb and As in soil. To achieve these goals, biochar was produced in a small-scale biochar producing plant, and an incubation experiment was conducted using a silt loam metal-contaminated soil treated with different application rates of biochar (0-10% w/w). The obtained results showed that, the addition of SC-BC and OP-BC increased significantly the soil aggregate stability, water-holding capacity, cation exchange capacity, organic matter and N-status in soil. SC-BC considerably decreased the solubility of Pb to values lower than the toxic regulatory level of the toxicity characteristics leaching procedure extraction (5mgL(-1)). The rise in soil pH caused by biochar application, and the increase of soil organic matter transformed the labile Pb into less available fractions i.e. ""Fe-Mn oxides"" and ""organic"" bound fractions. On the other hand, As was desorbed from Fe-Mn oxides, which resulted in greater mobility of As in the treated soil. We concluded that SC-BC and OP-BC could be used successfully for remediating soils highly contaminated with Pb. However, considerable attention should be paid when using it in soil contaminated with As.",
Arsenic,2149373,"Iron-containing nanomaterials: Synthesis, properties, and environmental applications Abstract: Available data on the iron-containing nanomaterials are reviewed. Main attention is paid to the following themes: synthetic methods, structures, composition and properties of the nano zerovalent iron (NZVI), and polymorphic forms of iron oxides and FeOOH. Synthetic methods summarized here include a series of physico-chemical methods such as microwave heating, electrodeposition, laser ablation, radiolytical techniques, arc discharge, metal-membrane incorporation, pyrolysis, combustion, reverse micelle and co-deposition routes. We have also included a few “greener” methods. Coated, doped, supported with polymers or inert inorganic materials, core–shell nanostructures, in particular those of iron and its oxides with gold, are discussed. Studies of remediation involving iron-containing nanomaterials are discussed and special attention is paid to the processes of remediation of organic contaminants (chlorine-containing pollutants, benzoic and formic acids, dyes) and inorganic cations (Zn(II), Cu(II), Cd(II) and Pb(II)) and anions (nitrates, bromates, arsenates). Water disinfection (against viruses and bacteria), toxicity and risks of iron nanomaterials application are also examined.",
Arsenic,1029358,"Biogeochemical controls of arsenic occurrence and mobility in the Indian Sundarban mangrove ecosystem Abstract: This study aims to investigate the control of arsenic distribution by biogeochemical processes in the Indian Sundarban mangrove ecosystem and the importance of this ecosystem as an arsenic source for surrounding coastal water. The As(V)/As(III) ratio was found to be significantly lower in both surface and pore waters compared to sea water, which could be attributed to biogeochemical interconversion of these arsenic forms. The biological uptake of arsenic due to primary and benthic production occurs during the post-monsoon season, and is followed by the release of arsenic during the biochemical degradation and dissolution of plankton in the pre-monsoon season. These results suggest that arsenic is immobilized during incorporation into the arsenic-bearing initial phase, and unlikely to be released into pore water until the complete microbial degradation of arsenic-bearing organic compounds.",
Arsenic,627231,"Determination of monomethylarsonous acid, a key arsenic methylation intermediate, in human urine Abstract: In this study we report on the finding of monomethylarsonous acid [MMA(III)] in human urine. This newly identified arsenic species is a key intermediate in the metabolic pathway of arsenic biomethylation, which involves stepwise reduction of pentavalent to trivalent arsenic species followed by oxidative addition of a methyl group. Arsenic speciation was carried out using ion-pair chromatographic separation of arsenic compounds with hydride generation atomic fluorescence spectrometry detection. Speciation of the inorganic arsenite [As(III)], inorganic arsenate [As(V)], monomethylarsonic acid [MMA(V)], dimethylarsinic acid [DMA(V)], and MMA(III) in a urine sample was complete in 5 min. Urine samples collected from humans before and after a single oral administration of 300 mg sodium 2,3-dimercapto-1-propane sulfonate (DMPS) were analyzed for arsenic species. MMA(III) was found in 51 out of 123 urine samples collected from 41 people in inner Mongolia 0-6 hr after the administration of DMPS. MMA(III )in urine samples did not arise from the reduction of MMA(V) by DMPS. DMPS probably assisted the release of MMA(III) that was formed in the body. Along with the presence of MMA(III), there was an increase in the relative concentration of MMA(V) and a decrease in DMA(V) in the urine samples collected after the DMPS ingestion.",
Arsenic,1339075,"The challenge of health &amp; environment: profiling risks &amp; strategic priorities for now &amp; the future Abstract: A substantial burden of communicable and non-communicable diseases in the developing countries is attributable to environmental risk factors. WHO estimates that the environmental factors are responsible for an estimated 24 per cent of the global burden of disease in terms of healthy life years lost and 23 per cent of all deaths; children being the worst sufferers. Given that the environment is linked with most of the Millennium Development Goals (MDGs), without proper attention to the environmental risk factors and their management, it will be difficult to achieve many MDGs by 2015. The impact of environmental degradation on health may continue well into the future and the situation in fact, is likely to get worse. In order to address this challenge, two facts are worth noting. First, that much of the environmental disease burden is attributable to a few critical risk factors which include unsafe water and sanitation, exposure to indoor smoke from cooking fuel, outdoor air pollution, exposure to chemicals such as arsenic, and climate change. Second, that environment and health aspects must become, as a matter of urgency, a national priority, both in terms of policy and resources allocation. To meet the challenge of health and environment now and in the future, the following strategic approaches must be considered which include conducting environmental and health impact assessments; strengthening national environmental health policy and infrastructure; fostering inter-sectoral co-ordination and partnerships; mobilizing public participation; and enhancing the leadership role of health in advocacy, stewardship and capacity building.",
Arsenic,1342625,Immobilization of novel the semicarbazone derivatives of calix[4]arene onto magnetite nanoparticles for removal of Cr(VI) ion Abstract: ,
Arsenic,2298696,"Distribution of arsenic and risk assessment of activities on a golf course fertilised with arsenic-containing Ascophyllum nodosum seaweed Abstract: The use of seaweed fertilisers in sports green maintenance has become a common practice across the globe due to its image as an &quot;eco-friendly&quot; alternative to chemical fertilisers. The aim of this study was to characterise the risk of human exposure to arsenic (As), via dermal absorption, from golfing activities on a private golf course in the UK, where As contaminated seaweed fertiliser (~100mg/kg d.wt.) is applied. This was fulfilled by, 1) determining As concentrations in shallow soils with GIS geo-statistical analysis, 2) measuring As concentrations from an on-site borehole groundwater well, and (3) developing a risk assessment calculation for golfing activities based on field and questionnaire data. Total As concentrations in shallow soils were less than the UK threshold for domestic soils, however, frequent and sustained dermal contact between site-users and surface soil attributed to a maximum carcinogenic risk value of 2.75×10(-4), which is in the upper limit of the acceptable risk range. Arsenic concentrations in underlying groundwater exceeded the WHO's permissible drinking water standard, demonstrating the risk of groundwater contamination following the application of seaweed fertiliser to golf course soils. This is the first risk study on dermal As absorption via the application of a seaweed fertiliser.",
Arsenic,1350200,"Ground Water Quality Assessment of Rural Area of Deoli Tehsil, Tonk District (Rajasthan) with Special Reference to Fluoride Analysis Abstract: ",
Arsenic,1508557,"Biomonitoring of arsenic through mangrove oyster (Crassostrea corteziensis Hertlein, 1951) from coastal lagoons (SE Gulf of California): Occurrence of arsenobetaine and other arseno-compounds Abstract: In this study, we examined the bioavailability of arsenic through the mangrove oyster Crassostrea corteziensis sampled from seven coastal lagoons in SE Gulf of California during the rainy and dry seasons. As concentrations in soft tissue of oysters C. corteziensis fluctuated between 5.2 and 11.6 ?g/g on dry weight; organisms from the control site presented the lowest As concentrations in the two sampling seasons. As speciation was evaluated in selected samples and indicated that arsenobetaine was the major arseno-compound accounting for 53.5-74.7 % of total As. Lower percentage contributions were obtained for nonextractable As (9.7-25.5 %) and other molecules such as arsenocholine and methyl-arsonate (&lt;5 %). Inorganic As was detectable in only two samples, at concentrations lower than 0.1 ?g/g. These As data are the first generated in NW Mexico and indicate that C. corteziensis is safe for human consumption in terms of arseno-compounds. It is evident that As bioavailability in these lagoons is low.",
Arsenic,1337716,"Arsenic remediation from drinking water using Fenton's reagent with slow sand filter Abstract: This paper describes the development of a remediation approach based on the pre-oxidation using Fenton's reagent and the subsequent removal of arsenic (As) through sand filtration from drinking water. The efficiency of the process was carried out including As(III) and As(V) with various concentration ratios up to 3,000 ppb. Efficient removal of As was observed within WHO guideline value of 10 ppb. The recoveries of samples were found to be 98 % ± 2.5 %. The process was applied to field samples, where results show considerable reduction in As concentrations. This process is cost effective for treatment of drinking water with high concentration of As.",
Arsenic,1677587,"Hair arsenic levels and prevalence of arsenicosis in three Cambodian provinces Abstract: Natural, inorganic arsenic contamination of groundwater threatens the health of more than 100 million people worldwide, including residents of the densely populated river deltas of South and Southeast Asia. Contaminated groundwater from tube wells in Cambodia was discovered in 2001 leading to the detection of the first cases of arsenicosis in 2006. The most affected area was the Kandal Province. The main objective of this study was to determine the prevalence of arsenicosis in Cambodia based on acceptable criteria, and to investigate the use of hair arsenic as a biomarker not only for arsenicosis-related signs but also for associated symptoms. A cross-sectional epidemiological study of 616 respondents from 3 purposely selected provinces within the Mekong River basin of Cambodia was conducted. The Kandal Province was chosen as a high arsenic-contaminated area, while the Kratie Province and Kampong Cham Province were chosen as moderate and low arsenic-contaminated areas, respectively. The most prevalent sign of arsenicosis was hypomelanosis with a prevalence of 14.5% among all respondents and 32.4% among respondents with a hair arsenic level of ?1?g/g. This was followed by hyperkeratosis, hyperpigmentation and mee's lines. Results also suggest a 1.0?g/g hair arsenic level to be a practical cut off point for an indication of an arsenic contaminated individual. This hair arsenic level, together with the presence of one or more of the classical signs of arsenicosis, seems to be a practical criteria for a confirmed diagnosis. Based on these criteria, the overall prevalence of arsenicosis for all provinces was found to be 16.1%, with Kandal Province recording the highest prevalence of 35.5%. This prevalence is comparatively high when compared to that of other affected countries. The association between arsenicosis and the use of Chinese traditional medicine also needs further investigation.",
Arsenic,1024709,"Occupation and skin cancer: The results of the HELIOS-I multicenter case-control study Abstract: <strong>BACKGROUND: </strong>Non-melanoma skin cancer (NMSC) is the most frequent tumour among Caucasian populations worldwide. Among the risk factors associated with this tumour, there are host-related factors and several environmental agents. A greater likelihood of high exposure to physical agents (with the exception of solar radiation) and chemical agents depends on the work setting. Our objective is to evaluate the role of occupational exposures in NMSC, with special emphasis on risk factors other than solar radiation and skin type.<br /><br /><strong>METHODS: </strong>We analysed 1585 cases (1333 basal cell carcinoma (BCC) and 183 squamous cell carcinoma (SCC)) and 1507 controls drawn from the Helios-I multicenter study. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression mixed models.<br /><br /><strong>RESULTS: </strong>For NMSC as a whole (both histological types), miners and quarrymen, secondary education teachers, and masons registered excess risk, regardless of exposure to solar radiation and skin type (OR 7.04, 95% CI 2.44-20.31; OR 1.75, 95% CI 1.05-2.89 and OR 1.54, 95% CI 1.04-2.27, respectively). Frequency of BCC proved higher among railway engine drivers and firemen (OR 4.55; 95% CI 0.96-21.57), specialised farmers (OR 1.65; 95% CI 1.05-2.59) and salesmen (OR 3.02; 95% CI 1.05-2.86), in addition to miners and quarrymen and secondary education teachers (OR 7.96; 95% CI 2.72-23.23 and OR 1.76; 95% CI 1.05-2.94 respectively). The occupations that registered a higher risk of SCC (though not of BCC) were those involving direct contact with livestock, construction workers not elsewhere classified (OR 2.95, 95% CI 1.12-7.74), stationary engine and related equipment operators not elsewhere classified (OR 5.31, 95% CI 1.13-21.04) and masons (OR 2.55, 95% CI 1.36-4.78).<br /><br /><strong>CONCLUSION: </strong>Exposure to hazardous air pollutants, arsenic, ionizing radiations and burns may explain a good part of the associations observed in this study. The Helios study affords an excellent opportunity for further in-depth study of physical and chemical agents and NMSC based on matrices of occupational exposure.",
Arsenic,2345772,"Coal mine drainage sludge and its application for treating metallic mine effluent Abstract: In this study, coal mine drainage sludge (CMDS) impregnated polyurethane granular composite media (PUCMDS) was prepared and used to remove arsenic and other heavy metals in a metallic mine effluent. PUCMDS was used in rapid small-scale column tests to assess the effectiveness and suitability in the application of metallic mine water treatment. As a result in column tests, good performance of PUCMDS was observed with respect to bed volumes (more than 14,000 BVs) achieved to treat arsenic and other toxic heavy metals below their regulations. Three cycles of media regeneration and four cycles of column tests were conducted to evaluate the performance of PUCMDS.",
Arsenic,627735,"Arsenic at very low concentrations alters glucocorticoid receptor (GR)-mediated gene activation but not GR-mediated gene repression: Complex dose-response effects are closely correlated with levels of activated GR and require a functional GR DNA binding domain Abstract: Arsenic (As) contamination of drinking water is considered a principal environmental health threat throughout the world. Chronic intake is associated with an increased risk of cancer, diabetes, and cardiovascular disease, and recent studies suggest increased health risks at levels as low as 5-10 ppb. We report here that 0.05-1 microM (6-120 ppb) As showed stimulatory effects on glucocorticoid receptor (GR)-mediated gene activation in rat EDR3 hepatoma cells of both the endogenous tyrosine aminotransferase (TAT) gene and the reporter genes containing TAT glucocorticoid response elements. At slightly higher concentrations (1-3 microM), the effects of As became inhibitory. Thus, over this narrow concentration range, the effects of As changed from a 2- to 4-fold stimulation to a greater than 2-fold suppression in activity. Interestingly, the inhibitory effect of GR on both AP1- and NF-kappa B-mediated gene activation was not affected by As. The magnitude of GR stimulation and inhibition by As was highly dependent on the cellular level of hormone-activated GR. Mutational deletion studies indicated that the central DNA binding domain (DBD) of GR is the minimal region required for the As effect and does not require free sulfhydryls. Point mutations located within the DBD that have known structural consequences significantly altered the GR response to As. In particular, point mutations in the DBD that confer a DNA-bound GR confirmation abolished the low dose As stimulatory effect but enhanced the inhibitory response, further indicating that the DBD is important for mediating these As effects.",
Arsenic,1350396,Arsenic enrichment in shelf and coastal sediment of the Brazilian subtropics Abstract: ,
Arsenic,1326781,"Enhanced glutathione biosynthetic capacity promotes resistance to As3+-induced apoptosis Abstract: Trivalent arsenite (As(3+)) is a known human carcinogen capable of inducing both cellular transformation and apoptotic cell death by mechanisms involving the production of reactive oxygen species. The tripeptide antioxidant glutathione (GSH) constitutes a vital cellular defense mechanism against oxidative stress. While intracellular levels of GSH are an important determinant of cellular susceptibility to undergo apoptotic cell death, it is not known whether cellular GSH biosynthetic capacity per se regulates As(3+)-induced apoptosis. The rate-limiting enzyme in GSH biosynthesis is glutamate cysteine ligase (GCL), a heterodimeric holoenzyme composed of a catalytic (GCLC) and a modifier (GCLM) subunit. To determine whether increased GSH biosynthetic capacity enhanced cellular resistance to As(3+)-induced apoptotic cell death, we utilized a mouse liver hepatoma (Hepa-1c1c7) cell line stably overexpressing both GCLC and GCLM. Overexpression of the GCL subunits increased GCL holoenzyme formation and activity and inhibited As(3+)-induced apoptosis. This cytoprotective effect was associated with a decrease in As(3+)-induced caspase activation, cleavage of caspase substrates and translocation of cytochrome c to the cytoplasm. In aggregate, these findings demonstrate that enhanced GSH biosynthetic capacity promotes resistance to As(3+)-induced apoptosis by preventing mitochondrial dysfunction and cytochrome c release and highlight the role of the GSH antioxidant defense system in dictating hepatocyte sensitivity to As(3+)-induced apoptotic cell death.",
Arsenic,2216502,"The impact of poultry litter application on sediment chemistry of the Broadkill River estuary system, Delaware Abstract: This project examined the impact of long-term poultry litter application on the chemical signatures of As, Cu, Zn, and P in stream sediments of the Broadkill River watershed within the Delmarva Peninsula, a region of intense poultry production. Thirty-seven sediment samples were collected from Broadkill River drainage systems and analyzed for litter-derived elements (As, Cu, Zn, P) and basic soil parameters such as particle size distribution, organic matter, and soluble salts. Results showed that concentrations of elements in stream sediments are approximately log-normally distributed. Spatial variability in concentrations of elements was evident, with most elements increasing in concentration and enrichment from upgradient headwaters to downgradient reaches draining predominantly agricultural areas. Results of correlation analyses showed positive significant correlation among elements; elements were also positively correlated with percent clay and silt in the sediment. Using GIS maps with overlays of hydrology and land use activities, statistical correlations between As, Cu, Zn, and P enrichment factors and land use were examined. Results showed statistically significant relationships between As, Mn, and Zn enrichment factors and residential areas within the watershed, but did not show a statistically significant relationship between element enrichment factors and agricultural land use. Factors that complicate this type of landscape-scale study include the presence of poultry processing plants, impoundments, changes in land use over time, and the influence of tides, all of which can have direct and indirect influences on element mobility.",
Arsenic,2343562,"Effect of Equilibrium Solution Ionic Strength on the Adsorption of Zn, Cu, Cd, Pb, As, and P on Aluminum Mining By-Product Abstract: This study evaluated the effect of the soil solution ionic strength (IS) on the adsorption of Zn, Cu, Cd, Pb, As, and P on aluminum mining by-product (AMB), as well as performed the toxicity characteristic leaching procedure test (TCLP) followed by semi-total digestion in order to evaluate whether the adsorbed elements can cause environmental health risks. We measured adsorption by reacting the adsorbent with Zn, Cu, Cd, Pb, As, and P solutions in low IS (47 mmol L-1) and high IS (470 mmol L-1). Subsequent cation and anion desorption was evaluated by adding electrolyte solutions to the remaining adsorption residue. After the desorption experiment, we performed the TCLP test followed by semi-total digestion. Changing the IS interfered on Zn, Cd, Cu, and As adsorption, while no effect was observed for Pb and P. Increasing IS decreased the desorbed amounts of Cd, Zn, Cu, and As. Among the studied elements, Cd and Zn were noteworthy for having adsorbed the least and desorbed the most. Disposal of the AMB after being used as adsorbent of Cd, Pb, and As has to be carefully made as it may present their contents above the concentration causing toxicity.",
Arsenic,2337100,"DISTRIBUTION AND MOBILITY OF ARSENIC AND ANTIMONY AT MINE SITES IN FYR MACEDONIA Abstract: Soils, river sediments and waters from former As-Sb mining sites in FYR Macedonia have been chemically analysed to assess their impact on the local environment. Soils and river sediments contain very high concentrations of As and Sb (medians 117 and 37 mg kg(-1)), but values are heterogeneously distributed. These values are far in excess of various statutory thresholds and at the largest deposit, Lojane, the area is grossly contaminated. Sequential extraction has demonstrated that a large proportion of the As (50-90%) and Sb (20-60%) in these soils is in a weakly-bound form and is thus available for further mobilization. Surface and groundwaters are neutral to alkaline because of interaction with host lithologies (e.g. serpentinite, dolomite and limestone). Surface waters appear to have higher concentrations of As (55;33) and Sb (2.1;0.6) than the groundwaters (medians, upsilon g/l). For all samples there is a close positive correlation between As and Sb, but As contents are generally much higher than those for Sb. Most of the waters have As concentrations which exceed the 10 upsilon g I-1 value accepted for safe drinking water whereas most Sb concentrations are much lower and appear to be within the acceptable limits for this element. The alkaline waters have been able to mobilize the As and Sb directly from the primary ore minerals and the lack of pyrite in the ores has minimized the production of secondary Fe oxides which could adsorb and immobilize these elements. These sites are environmental 'hotspots' and need remediation. The reservoir of As and Sb which is able to be released over a long time period threatens a much larger area. Remediation strategies would have to take the mobility of these elements under alkaline conditions into account.",
Arsenic,1338750,"Angiotensin II potentiates ?-adrenergic vasoconstriction in the elderly Abstract: Aging is characterized by increased sympatho-excitation, expressed through both the ?-adrenergic and RAAS (renin-angiotensin-aldosterone) pathways. Although the independent contribution of these two pathways to elevated vasoconstriction with age may be substantial, significant cross-talk exists that could produce potentiating effects. To examine this interaction, 14 subjects (n=8 young, n=6 old) underwent brachial artery catheterization for administration of AngII (angiotensin II; 0.8-25.6 ng/dl per min), NE [noradrenaline (norepinephrine); 2.5-80 ng/dl per min] and AngII with concomitant ?-adrenergic antagonism [PHEN (phentolamine); 10 ?g/dl per min]. Ultrasound Doppler was utilized to determine blood flow, and therefore vasoconstriction, in both infused and contralateral (control) limbs. Arterial blood pressure was measured directly, and sympathetic nervous system activity was assessed via microneurography and plasma NE analysis. AngII sensitivity was significantly greater in the old, indicated by both greater maximal vasoconstriction (-59±4% in old against -48±3% in young) and a decreased EC50 (half-maximal effective concentration) (1.4±0.2 ng/dl per min in old against 2.6±0.7 ?g/dl per min in young), whereas the maximal NE-mediated vasoconstriction was similar between these groups (-58±9% in old and -62±5% in young). AngII also increased venous NE in the old group, but was unchanged in the young group. In the presence of ?-adrenergic blockade (PHEN), maximal AngII-mediated vasoconstriction in the old was restored to that of the young (-43±8% in old and -39±6% in young). These findings indicate that, with healthy aging, the increased AngII-mediated vasoconstriction may be attributed, in part, to potentiation of the ?-adrenergic pathway, and suggest that cross-talk between the RAAS and adrenergic systems may be an important consideration in therapeutic strategies targeting these two pathways.",
Arsenic,2347580,"Surface complexation of antimony on kaolinite Abstract: Geochemical fate of antimony (Sb) - a similar oxyanion as arsenic (As) - in a variety of environment is largely unexplored. Kaolinite is an important, naturally occurring clay mineral in soils and aquifers and is known to control the fate of several contaminants via a multitude of geochemical processes, primarily adsorption. Here we report adsorption of antimony on kaolinite as a function of solution chemistry: initial antimony concentration, pH, ionic strength, and a competing anion. A surface complexation modeling (SCM) approach was undertaken to understand the potential mechanistic implications of sorption envelope data. In the SCM, a multicomponent additive approach, in which kaolinite is assumed to be a (1:1) mixture of quartz (SiOH) and gibbsite (AlOH), was tested. Results indicated that ionic strength has a minimal effect on antimony adsorption. For the lower initial antimony concentration (4.11?M), the additive model with binuclear surface complexes on quartz and gibbsite showed a better fit at pH&lt;6, but somewhat under predicted the experimental data above pH 6. At the higher initial antimony concentration (41.1?M), the sorption envelope was of different shape than the lower load. The additive model, which considered binuclear surface complexes for quartz and gibbsite, resulted in over prediction of the adsorption data at pH&gt;3.5. However, the additive model with binuclear surface complex on quartz and mononuclear surface complex on gibbsite showed an excellent fit of the data. Phosphate greatly influenced antimony adsorption on kaolinite at both low and high antimony loadings, indicating competition for available surface sites.",
Arsenic,1597303,"Breakthrough studies with mono-, binary- and ternary-ion systems comprised of Fe(II), F(-) and As(III) using river sand packed columns for groundwater treatment Abstract: Groundwater in Assam, India, contains excessive amounts of arsenic (As(III)), fluoride (F(-)) and iron (Fe(II)). The rural and semi-urban population of Assam uses indigenous iron filters fabricated using processed sand (PS) as one of the chief constituents to reduce Fe(II) concentration; however, no efforts have been made to reduce As(III) or F(-) concentrations before use. The present work is directed towards assessing the potential of PS for removal of these ions from mono-, binary- and ternary-ion systems through continuous mode column studies. Synthetic water samples containing fixed concentration of ions were prepared using deionized water. The observed order of breakthrough of ions was: As(III) followed by Fe(II) and F(-) followed by Fe(II) in the case of the binary ion systems of Fe(II) + As(III) and Fe(II) + F(-). The throughput volume for As(III) in the (Fe(II) + As(III)) system and for F(-) in the (Fe(II) + F(-)) system is termed the critical breakthrough throughput volume. In the ternary ion system (Fe(II) + As(III) + F(-)), the order of breakthrough of ions observed was F(-), then As(III) and then Fe(II) and hence the throughput volume F(-) is termed the critical breakthrough throughput volume. Results of column studies also indicate the impact on the uptake of the selected ion by the presence of the other ion present in the binary- and ternary-ion systems.",
Arsenic,1027595,"Genotoxicity of sodium arsenite and DNA fragmentation in ovarian cells of rat Abstract: Present study examined the genotoxic effects of arsenite in ovarian tissue of rat at 56 days of age. Immature (28 days old) female rats were exposed to different doses (50, 100, and 200 ppm) of sodium arsenite in drinking water for 28 days. DNA damage in ovarian tissue was measured by comet assay. All doses induced significant decrease in ovarian weight in a dose-dependent manner compared to control, more prominently at (P&lt;0.001) 100 and 200 ppm. All the comet assay parameters showed significant difference with arsenite treatment compared to control group. In treatment groups, mean number of cells with intact DNA decreased while, mean comet number increased (P&lt;0.001) in a dose-dependent manner compared to control. Significant decrease (P&lt;0.05) was observed in mean comet length, height, comet head diameter and %DNA in comet head of high dose groups compared to control group. Dose dependent increase was found in mean comet tail length, %DNA in tail, tail moment and olive tail moment in high dose groups compared to control group. The study indicates that arsenic caused DNA damage to ovarian cells particularly at high doses and ensure comet assay as an effective method to detect DNA damage in tissue caused by metals.",
Arsenic,1022112,"Occupational dust and radiation exposure and mortality from stomach cancer among German uranium miners, 1946–2003 Abstract: Objectives 'Dusty occupations' and exposure to low-dose radiation have been suggested as potential risk factors for stomach cancer. Data from the German uranium miner cohort study are used to further evaluate this topic. Methods The cohort includes 58?677 miners with complete information on occupational exposure to dust, arsenic and radiation dose based on a detailed job-exposure matrix. A total of 592 stomach cancer deaths occurred in the follow-up period from 1946 to 2003. A Poisson regression model stratified by age and calendar year was used to calculate the excess relative risk (ERR) per unit of cumulative exposure to fine dust or from cumulative absorbed dose to stomach from ? or low-LET (low linear energy transfer) radiation. For arsenic exposure, a binary quadratic model was applied. Results After adjustment for each of the three other variables, a statistically non-significant linear relationship was observed for absorbed dose from low-LET radiation (ERR/Gy=0.30, 95% CI -1.26 to 1.87), ? radiation (ERR/Gy=22.5, 95% CI -26.5 to 71.5) and fine dust (ERR/dust-year=0.0012, 95% CI -0.0020 to 0.0043). The relationship between stomach cancer and arsenic exposure was non-linear with a 2.1-fold higher RR (95% CI 0.9 to 3.3) in the exposure category above 500 compared with 0 dust-years. Conclusion Positive statistically non-significant relationships between stomach cancer and arsenic dust, fine dust and absorbed dose from ? and low-LET radiation were found. Overall, low statistical power due to low doses from radiation and dust are of concern.",
Arsenic,1677599,"Arsenate and Phosphate Adsorption in Relation to Oxides Composition in Soils: LCD Modeling Abstract: The pH dependent solid-solution distribution of arsenate and phosphate in five Dutch agricultural soil samples was measured in the pH range 4-8, and the results were interpreted using the LCD (ligand and charge distribution) adsorption modeling. The pH dependency is similar for both oxyanions, with a minimum soluble concentration observed around pH 6-8. This pH dependency can be successfully described with the LCD model and it is attributed mainly to the synergistic effects from Ca adsorption. The solubility of phosphate is much lower than that of arsenate. This big difference cannot be sufficiently explained by the reduction of small amount of As(V) into As(III), neither by slow desorption/adsorption. The difference between phosphate and arsenate in their solid-solution distribution becomes larger with the increase of aluminum (hydr)oxides (Al-oxides) contribution to the total amount of metal (Al and Fe) (hydr)oxides. The influence of Al-oxides is much larger than its relative amount extracted from the soils. When Al-oxides account for &gt;40% of the soil oxides, the whole adsorbents behave apparently similarly to that of pure Al-oxides. These results indicated that surface coating and substitution may have modified significantly oxyanion adsorption to Fe-oxides in soils, and how to account for this complexity is a challenge for geochemical modeling.",
Arsenic,2347655,"Diversity and spatiotemporal dynamics of bacterial communities: physicochemical and others drivers along an acid mine drainage Abstract: Deciphering the biotic and abiotic factors that control microbial community structure over time and along an environmental gradient is a pivotal question in microbial ecology. Carnoulès mine (France), which is characterized by acid waters and very high concentrations of arsenic, iron and sulfate, provides an excellent opportunity to study these factors along the pollution gradient of Reigous Creek. To this end, biodiversity and spatiotemporal distribution of bacterial communities were characterized using T-RFLP fingerprinting and highthrouput sequencing. Patterns of spatial and temporal variations in bacterial community composition linked to changes in the physicochemical conditions suggested that species-sorting processes were at work in the acid mine drainage. Arsenic, temperature and sulfate appeared to be the most important factors that drove the composition of bacterial communities along this continuum. Time series investigation along the pollution gradient also highlighted habitat specialization for some major members of the community (Acidithiobacillus and Thiomonas), dispersal for Acidithiobacillus and evidence of extinction/re-thriving processes for Gallionella. Finally pyrosequencing revealed a broader phylogenetic range of taxa than previous clone library-based diversity. Overall, our findings suggest that in addition to environmental filtering processes additional forces (dispersal, birth/death events) could operate in AMD community. This article is protected by copyright. All rights reserved.",
Arsenic,1070347,"Arsenic-induced inhibition of hippocampal neurogenesis and its reversibility Abstract: Arsenic exposure can result in damages of the neurological system. The present study aimed at whether cell proliferation and neurogenesis in the adult mouse hippocampus were affected after arsenic exposure and whether they could recover after exposure cessation. Mice were randomly placed into 3 groups. The first group received distilled water alone for 4 months (control group); the second group received 4.0mg/L As(2)O(3) through drinking water for 4 months (arsenic group); the third group received 4.0mg/L As(2)O(3) for 2 months and then changed to distilled water for another 2 months (recovery group). Serum and cerebrum arsenic concentrations of the arsenic group were significantly elevated, and then decreased to normal after the change of arsenic to water in the diet. After a four-month administration, the hippocampal number of proliferative cells and the percentage of new mature neurons decreased in the arsenic group as compared with the control group, however, increased significantly in the recovery group when compared with the arsenic group, and restored to the control level. There were no significant differences for apoptosis in different groups. Obvious histopathological ameliorations were observed in the hippocampus of the recovery group. The inhibition of hippocampus cell proliferation and neurogenesis by arsenic is reversible after the arsenic administration was terminated.",
Arsenic,628146,"Pro-angiogenesis action of arsenic and its reversal by selenium-derived compounds Abstract: Inorganic arsenic (arsenite and arsenate) in drinking water has been associated with skin cancers and increased incidence of cardiovascular diseases. Additionally, studies have demonstrated the pro-angiogenic effect of arsenite and its potential promotion of tumor angiogenesis and tumor progression. Furthermore, recent reports demonstrated reversal of skin co-carcinogenesis by an organoselenium compound. The present study was undertaken to determine the effect and mechanism on angiogenesis of arsenite at low level and its potential reversal by various selenium-derived compounds. The pro-angiogenesis effects and mechanisms of sodium arsenite were determined using the chick chorioallantoic membrane (CAM) model over 3 days and compared with standard pro-angiogenesis factors, such as basic fibroblast growth factor (b-FGF). Additionally, the potential effect of various selenium-derived compounds--such as dimethyl selenone, diphenyl selenone, sodium selenite or Se-methyl selenocysteine--in reversing the pro-angiogenesis effect of arsenite or b-FGF was also determined in the CAM model. The pro-angiogenesis effect of arsenite or b-FGF was significantly (P < 0.01) blocked by dimethyl selenone, diphenyl selenone, sodium selenite or Se-methyl selenocysteine. The pro-angiogenesis effect of either sodium arsenite at 33 nM or b-FGF was blocked (P < 0.01) by the extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation inhibitor, PD 98059. Additionally, the pro-angiogenic effect of arsenic or b-FGF was blocked as well (P < 0.01) by the alphavbeta3 antagonist, XT199. These data suggest that the pro-angiogenesis effect of arsenic is initiated at the plasma membrane integrin alphavbeta3, involves activation of the ERK1/2 pathway and is effectively reversed by various selenium-derived compounds.",
Arsenic,1255524,"Bioremediation and human tolerance to heavy metals through microbial processes: A potential role for probiotics? Abstract: The food and water we consume are often contaminated with a range of chemicals and heavy metals such as lead, cadmium, arsenic, chromium and mercury that are able to cause debilitating health complications. Though heavy metal exposure and contamination are not a recent phenomenon, the concentration of metals and exposure to populations remains a major issue despite remediation interventions. The ability to prevent and manage this problem is still a subject of much debate with many ineffective technologies and others too expensive for practical large- scale use, especially for developing nations where major pollution occurs. This has led researchers to seek alternative solutions for decontaminating environmental sites and humans themselves. A number of environmental microorganisms have long been known for their ability to bind metals, but less well appreciated are human gastrointestinal bacteria. Species such as Lactobacillus present in the human mouth, gut and vagina and in fermented foods, have the ability to bind and detoxify some of these substances. This review examined the current understanding of detoxication mechanisms of lactobacilli and how in the future humans and animals might benefit from these organisms in remediating environmental contamination of food.",
Arsenic,2279171,"Effects of Arsenate and Arsenite on Germination and Some Physiological Attributes of Barley Hordeum vulgare L Abstract: Arsenic (As) is toxic to plants and animals. We tested the effects of arsenite and arsenate (0-16 mg/L) on seed germination, and on relative root and shoot length, ?-amylase activity, reducing sugars and soluble total protein contents, and malondialdehyde content in barley seedlings. We also measured As accumulation in barley stems and roots. The ?-amylase activity, relative root and shoot length, and seed germination decreased with increasing concentrations of arsenate and arsenite. The reducing sugars content in barley seedlings increased after 4 days of growth on media containing As. In general, the protein content in roots and seedlings decreased with increasing doses of As. Arsenic in the tissues was quantified by hydride generation-atomic absorption spectrophotometry. To confirm the accuracy of the method, we analyzed the certified reference material WEPAL-IPE-168. The limit of detection was 1.2 ?g/L and the relative standard deviation was &lt;2.0 %.",
Arsenic,1337655,"Methyl group balance in brain and liver: Role of choline on increased S-adenosyl methionine (SAM) demand by chronic arsenic exposure Abstract: Arsenic toxicity has been related to its interference with one carbon metabolism, where a high demand of S-adenosylmethionine (SAM) for arsenic methylation as well as a failure of its regeneration would compromise the availability of methyl groups for diverse cellular functions. Since exposed animals show disturbances of methylated products such as methylated arginines, myelin and axon membranes, this work investigates whether alterations of SAM, choline and phosphatidylcholine (PC) in the brain of arsenic exposed rats are associated with myelin alterations and myelin basic protein (MBP) immunoreactivity. Also these metabolites, morphologic and biochemical markers of methyl group alterations were analyzed in the liver, the main site of arsenic methylation. In adult, life-long arsenic exposed rats through drinking water (3ppm), no changes of SAM, choline and PC concentrations where found in the brain, but SAM and PC were severely decreased in liver accompanied by a significant increase of choline. These results suggest that choline plays an important role as methyl donor in arsenic exposure, which could underlie hepatic affections observed when arsenic exposure is combined with other environmental factors. Also, important myelin and nerve fiber alterations, accompanied by a 75% decrease of MBP immunoreactivity were not associated with a SAM deficit in the brain.",
Arsenic,2337207,"Novel chitosan/PVA/zerovalent iron biopolymeric nanofibers with enhanced arsenic removal applications Abstract: Enhanced removal application of both forms of inorganic arsenic from arsenic-contaminated aquifers at near-neutral pH was studied using a novel electrospun chitosan/PVA/zerovalent iron (CPZ) nanofibrous mat. CPZ was carefully examined using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), atomic fluorescence spectroscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). Application of the adsorbent towards the removal of total inorganic arsenic in batch mode has also been studied. A suitable mechanism for the adsorption has also been discussed. CPZ nanofibers mat was found capable to remove 200.0?±?10.0 mg g(-1) of As(V) and 142.9?±?7.2 mg g(-1) of As(III) from aqueous solution of pH 7.0 at ambient condition. Addition of ethylenediaminetetraacetic acid (EDTA) enabled the stability of iron in zerovalent state (ZVI). Enhanced capacity of the fibrous mat could be attributed to the high surface area of the fibers, presence of ZVI, and presence of functional groups such as amino, carboxyl, and hydroxyl groups of the chitosan and EDTA. Both Langmuir and Freundlich adsorption isotherms were applicable to describe the removal process. The possible mechanism of adsorption has been explained in terms of electrostatic attraction between the protonated amino groups of chitosan/arsenate ions and oxidation of arsenite to arsenate by Fentons generated from ZVI and subsequent complexation of the arsenate with the oxidized iron. These CPZ nanofibrous mats has been prepared with environmentally benign naturally occurring biodegradable biopolymer chitosan, which offers unique advantage in the removal of arsenic from contaminated groundwater.",
Arsenic,1342644,Protein binding interaction of warfarin and acetaminophen in presence of arsenic and of the biological system Abstract: ,
Arsenic,1025848,"Investigation on the genotoxic effects of long-term administration of sodium arsenite in bone marrow and testicular cells in vivo using the comet assay Abstract: The main source of environmental arsenic exposure in most populations is drinking water in which inorganic forms of arsenic predominate. The single-cell gel electrophoresis technique (the comet assay) measures DNA damage, including double-strand and single-strand breaks, in somatic cells after a variety of genotoxic insults. We have used this method to measure damage to cellular DNA in the bone marrow and testicular cells of mice using the alkaline comet assay for the former and neutral comet assay for the latter. Swiss albino male mice were exposed to sodium arsenite in drinking water at concentrations of 10, 50,100, and 200 mg/l for a period of three months. Concurrently, negative and positive control sets were maintained. The negative control animals were given distilled water as drinking water for the same period of treatment while the animals in positive control sets were either given single or multiple injections of EMS (100 mg/kg body weight) according to the tissue sampled. Following long-term exposure, there was a significant dose-dependent reduction in the size and weight of testes. The comet parameters of DNA, such as tail length (microm), % of DNA in tail, and Olive tail moment (arbitrary units) were increased in both bone marrow and testicular cells due to arsenic-induced DNA strand breaks. A positive dose response relationship was noted. The magnitude of DNA strand break was more pronounced in the bone marrow cells than in the testicular cells. The minimum effective concentrations for inducing DNA damage in bone marrow cells and testicular cells were 10 mg/l and 50 mg/l, respectively. The results of the study indicate that arsenic in drinking water is genotoxic in mice and the comet assay can be used for examining DNA damage in testicular cells as a parameter for evaluating male reproductive toxicity.",
Arsenic,1936173,"Arsenic Induced Toxicity in Broiler Chicks and Its Amelioration with Ascorbic Acid: Clinical, Hematological and Pathological Study Abstract: ",
Arsenic,1677576,"Monomethylated trivalent arsenic species disrupt steroid receptor interactions with their DNA response elements at non-cytotoxic cellular concentrations Abstract: Arsenic (As) is considered a top environmental chemical of human health because it has been linked to adverse health effects including cancer, diabetes, cardiovascular disease, and reproductive and developmental problems. In several cell culture and animal models, As acts as an endocrine disruptor, which may underlie many of its health effects. Previous work showed that steroid receptor (SR)-driven gene expression is disrupted in cells treated with inorganic As (arsenite, iAs(+3)). In those studies, low iAs(+3) concentrations (0.1-0.7 ?M) stimulated hormone-inducible transcription, whereas somewhat higher but still non-cytotoxic levels (1-3 ?M) inhibited transcription. This investigation focuses on the mechanisms underlying these inhibitory effects and evaluates the role of methylated trivalent As metabolites on SR function. Recent evidence suggests that, compared with iAs, methylated forms may have distinct biochemical effects. Here, fluorescence polarization (FP) experiments utilizing purified, hormone-bound human glucocorticoid (GR) and progesterone receptor (PR) have demonstrated that neither inorganic (iAs(+3)) nor dimethylated (DMA(+3)) species of trivalent As affect receptor interactions with glucocorticoid DNA response elements (GREs). However, monomethylated forms (monomethylarsenite, MMA(+3) and monomethylarsonic diglutathione, MADG) strongly inhibit GR-GRE and PR-GRE binding. Additionally, speciation studies of iAs(+3) -treated H4IIE rat hepatoma cells show that, under treatment conditions that cause inhibition of hormone-inducible gene transcription, the intracellular concentration of MADG is sufficient to inhibit GR-GRE and PR-GRE interactions in vivo. These results indicate that arsenic's inhibitory endocrine disruption effects are probably caused in part by methylated metabolites' disruption of SR ability to bind DNA response elements that are crucial to hormone-driven gene transcription.",
Arsenic,1936032,"Application of iodine metabolism analysis methods in thyroid diseases Abstract: The main physiological role of iodine in the body is to synthesize thyroid hormone.Both iodine deficiency and iodine excess can lead to severe thyroid diseases.While its role in thyroid diseases has increasingly been recognized,few relevant platforms and techniques for iodine detection have been available in China.This paper summarizes the advantages and disadvantages of currently iodine detection methods including direct titration,arsenic cerium catalytic spectrophotometry,chromatography with pulsed amperometry,colorimetry based on automatic biochemistry,inductively coupled plasma mass spectrometry,so as to optimize the iodine nutrition for patients with thyroid diseases.",
Arsenic,1016996,"The accumulation, distribution, and toxicological effects of dietary arsenic exposure in lake whitefish (Coregonus clupeaformis) and lake trout (Salvelinus namaycush) Abstract: A 20-day experiment was conducted to compare the accumulation, distribution, and toxicological effects of dietary As, as arsenate, in lake whitefish (LWF, Coregonus clupeaformis) and lake trout (LT, Salvelinus namaycush). Results of this experiment were used to design an experiment of longer duration in which one of the fish species was selected and exposed three times per week to lower dietary As doses. In the present study each treatment group was exposed to a combination of one of three doses of As (0, 100, or 1000 microg As/g) and one of two types of diet, no brine shrimp (NS) or with brine shrimp (WS) for a total of eight dosing events. Brine shrimp were added to determine whether their presence enhanced consumption of As-contaminated food. Modified feeding behavior occurred in both fish species fed As contaminated diets, with the exception of the 100 microg As/g NS food. Brine shrimp addition did not affect feed consumption of the As contaminated diets. Significant As accumulation occurred in stomach, pyloric caeca, intestine, liver, kidney, and gallbladder, but not in bile or muscle. As exposure did not have a significant effect on hepatic and renal metallothionein concentrations. Concentrations of lipid peroxides were only significantly elevated in the plasma of LT fed the 1000 microg As/g WS food. Liver somatic indices decreased significantly in both species, whereas hematological parameters were not affected in either species. Histological lesions occurred in gallbladder, liver, kidney, pyloric caeca and intestine from LWF. These lesions were not observed in LT; however, gallbladders were not examined in this species. Weight gain was lower in both species fed As contaminated diets, however, condition factors were not affected.",
Arsenic,1026422,"Lipid peroxidation in workers exposed to aluminium, gallium, indium, arsenic, and antimony in the optoelectronic industry Abstract: <strong>OBJECTIVE: </strong>The objective of this study was to investigate whether exposure to aluminum, gallium, indium, arsenic, and antimony induces lipid peroxidation in humans.<br /><br /><strong>METHODS: </strong>Whole blood and urine levels of 103 exposed electronic industry workers and 67 referents were analyzed by use of inductively coupled plasma mass spectrometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography.<br /><br /><strong>RESULTS: </strong>The mean plasma MDA level in the 103 workers was significantly higher than that in 67 referents. The levels of MDA in the exposed workers were correlated significantly with the levels of urinary gallium and arsenic.<br /><br /><strong>CONCLUSIONS: </strong>Malondialdehyde as an index of lipid peroxidation can be induced by gallium and arsenic exposure. By reducing exposure to these metals, biologic effects such as lipid peroxidation may also be diminished.",
Arsenic,1337675,"EMT and CSC-like properties mediated by the IKK?/I?B?/RelA signal pathway via the transcriptional regulator, Snail, are involved in the arsenite-induced neoplastic transformation of human keratinocytes Abstract: Exposure of humans to inorganic arsenic can cause skin cancer. The epithelial-mesenchymal transition (EMT) and acquisition of cancer stem cell (CSC)-like properties are essential steps in the initiation of human skin cancers; however, the mechanisms of action remain obscure. We have found that, during the neoplastic transformation induced by a low concentration (1.0 ?M) of arsenite in human keratinocyte HaCaT cells, the cells undergo an EMT and then acquire a malignant CSC-like phenotype. With longer times for transformation of HaCaT cells, there were increased activations of I?B kinase ? (IKK?), inhibitor nuclear factor-kappa B alpha (I?B?), and nuclear factor ?B (NF-?B) RelA and increases in the level of Snail. Further, during the transformation of HaCaT cells, the activation of NF-?B RelA up-regulated Snail levels. Inhibition of NF-?B RelA blocked the arsenite-induced EMT, acquisition of a CSC-like phenotype, and neoplastic transformation. These observations show that EMT, along with acquisition of a CSC-like phenotype mediated by IKK?/I?B?/RelA signal pathway via Snail, contributes to a low concentration of arsenite-induced tumorigenesis.",
Arsenic,1358308,"The Sulfhydryl Group and Carcinogenesis Abstract: The interactions between the sulfhydryl (SH) group and various carcinogens are reviewed with emphasis on the uncontrolled proliferation of malignant neoplasia. The role of the SH group in normal cell division and growth, and its stimulating activity on cell division are examined briefly. Growth inhibition and stimulation by carcinogens is examined, and the interaction of carcinogens with SH groups is reviewed in detail, with emphasis on polycyclic aromatic hydrocarbons, hormones, hepatocarcinogens, alkylating agents, N-alkyl-N-nitroso compounds and N-nitrosodialkylamines, 4-nitroquinoline-N-oxide (56575), lactones, quinones and related products, metals and derivatives, arsenic (7440382), polymers and radiation. Examination of the interaction of SH reactive agents of unknown action or without carcinogenic action includes SH reagents, lacrimators and vesicants, alloxan (50715), maleimides and analogs, and maleic-hydrazide (123331). The role of the SH group in skin and liver carcinogenesis is investigated, and the SH metabolic systems involved in carcinogenesis are reviewed with emphasis on the glutathione-reductase system, inhibition of systems specifically requiring glutathione, synthesis of glutathione, and the role of hormones in glutathione metabolism. The author concludes that the possibility remains that carcinogens may not act on the specific SH synthesizing system but rather on SH groups associated with the nucleic acids responsible for the synthesis and regulation of the corresponding enzyme systems.",
Arsenic,1022044,"Predicting arsenic relative bioavailability in contaminated soils using meta analysis and relative bioavailability-bioaccessibility regression models Abstract: A number of in vitro assays are available for the determination of arsenic (As) bioaccessibility and prediction of As relative bioavailability (RBA) to quantify exposure for site-specific risk assessment. These data are usually considered in isolation; however, meta analysis may provide predictive capabilities for source-specific As bioaccessibility and RBA. The objectives of this study were to predict As RBA using previously published in vivo/in vitro correlations and to assess the influence of As sources on As RBA independent of geographical location. Data representing 351 soils (classified based on As source) and 514 independent bioaccessibility values were retrieved from the literature for comparison. Arsenic RBA was predicted using published in vivo/in vitro regression models, and 90th and 95th percentiles were determined for each As source classification and in vitro methodology. Differences in predicted mean As RBA were observed among soils contaminated from different As sources and within source materials when various in vitro methodologies were utilized. However, when in vitro data were standardized by transforming SBRC intestinal, IVG, and PBET data to SBRC gastric phase values (through linear regression models), predicted As RBA values for As sources followed the order CCA posts ? herbicide/pesticide &gt; mining/smelting &gt; gossan soils with 95th percentiles for predicted As RBA of 78.0, 78.4, 67.0, and 23.7%, respectively.",
Arsenic,1579357,"Fluoride and Arsenic in an Alluvial Aquifer System in Chihuahua, Mexico: Contaminant Levels, Potential Sources, and Co-occurrence Abstract: ",
Arsenic,2347552,"Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy Abstract: The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (?-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (?-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils.",
Arsenic,1597377,"Comparative and competitive adsorption of Cr(VI), As(III), and Ni(II) onto coconut charcoal Abstract: This study evaluates the behavior of coconut charcoal (AC) to adsorb Cr(VI), As(III), and Ni(II) in mono- and multicomponent (binary and ternary) systems. Batch experiments were carried out for mono- and multicomponent systems with varying metal ion concentrations to investigate the competitive adsorption characteristics. The adsorption kinetics followed the mechanism of the pseudo-second-order equation in both single and binary systems, indicating chemical sorption as the rate-limiting step of adsorption mechanism. Equilibrium studies showed that the adsorption of Cr(VI), As(III), and Ni(II) followed the Langmuir model and maximum adsorption capacities were found to be 5.257, 0.042, and 1.748 mg/g, respectively. In multicomponent system, As(III) and Ni(II) adsorption competed intensely, while Cr(VI) adsorption was much less affected by competition than As(III) and Ni(II). With the presence of Cr(VI), the adsorption capacities of As(III) and Ni(II) on AC were higher than those in single system and the metal sorption followed the order of Ni(II) &gt; As(III) &gt; Cr(VI). The results from the sequential adsorption-desorption cycles showed that AC adsorbent held good desorption and reusability.",
Arsenic,627490,"Risk of erectile dysfunction induced by arsenic exposure through well water consumption in Taiwan Abstract: BACKGROUND: Erectile dysfunction (ED) has a profound impact on the quality of life of many men. Many risk factors are associated with ED, such as aging, sex hormone levels, hypertension, cardiovascular diseases, and diabetes mellitus. Arsenic exposure could damage peripheral vessels and increase the risk of cardiovascular disease. However, the relationship between arsenic exposure and ED has seldom been evaluated. OBJECTIVES: In this study we aimed to investigate whether exposure to arsenic enhances the risk of ED. METHODS: We recruited 177 males >or= 50 years of age through health examinations conducted in three hospitals in Taiwan. We used a questionnaire (International Index of Erectile Function-5) to measure the level of erectile function. Sex hormones, including total testosterone and sex hormone-binding globulin, were determined by radioimmunoassay. We used another standardized questionnaire to collect background and behavioral information (e.g., cigarette smoking; alcohol, tea, or coffee drinking; and physical activity). RESULTS: The prevalence of ED was greater in the arsenic-endemic area (83.3%) than in the non-arsenic-endemic area (66.7%). Subjects with arsenic exposure > 50 ppb had a significantly higher risk of developing ED than those with exposure <or= 50 ppb, after adjusting for age, cigarette smoking, diabetes mellitus, hypertension, and cardiovascular disease [odds ratio (OR) = 3.4]. Results also showed that the risk of developing severe ED was drastically enhanced by arsenic exposure (OR = 7.5), after adjusting for free testosterone and traditional risk factors of ED. CONCLUSIONS: Results suggested that chronic arsenic exposure has a negative impact on erectile function.",
Arsenic,710985,"Maternal drinking water arsenic exposure and perinatal outcomes in Inner Mongolia, China Abstract: Bayingnormen is a region located in western Inner Mongolia China, with a population that is exposed to a wide range of drinking water arsenic concentrations. The relationship between maternal drinking water arsenic exposure and perinatal endpoints (term birth weight, preterm birth, stillbirth and neonatal death) in this region was evaluated in this study.<br /><br /> An analysis was conducted of all singleton deliveries in a defined geographical area of Inner Mongolia from December 1996 to December 1999 (n=9890). Outcome and covariate data were abstracted from prenatal care records. Exposure was based on well-water measures for the maternal subvillage. Mean birth weight at term was compared across four arsenic categories using analysis of covariance. ORs for stillbirth, preterm birth and neonatal death were estimated by logistic regression with arsenic exposure dichotomised at 50 microg/l.<br /><br /> Term birth weight was 0.05 kg higher (95% CI 0.02 to 0.08) in the highest exposure category (>100 microg/l) compared to the reference (below limit of detection to 20 microg/l). Arsenic >50 microg/l was associated with an increased risk of neonatal death (OR 2.01, 95% CI 1.12 to 3.59). No relationship was found between maternal arsenic exposure and preterm or stillbirth delivery.<br /><br /> At the levels observed in our study, arsenic does not appear to contribute to adverse birth outcomes. Exposure may play a role in neonatal death; however, the neonatal death rate in this population was low and this potential association merits further research.",
Arsenic,1355444,Development of cation exchanger-based nano-CdS hybrid catalyst for visible-light photodegradation of rhodamine B from water Abstract: ,
Arsenic,1327019,"Long-lasting genomic instability following arsenite exposure in mammalian cells: the role of reactive oxygen species Abstract: Previously, we reported that the progeny of mammalian cells, which has been exposed to sodium arsenite for two cell cycles, exhibited chromosomal instability and concurrent DNA hypomethylation, when they were subsequently investigated after two months of subculturing (about 120 cell generations) in arsenite-free medium. In this work, we continued our investigations of the long-lasting arsenite-induced genomic instability by analyzing additional endpoints at several time points during the cell expanded growth. In addition to the progressive increase of aneuploid cells, we also noted micronucleated and multinucleated cells that continued to accumulate up to the 50th cell generation, as well as dicentric chromosomes and/or telomeric associations and other complex chromosome rearrangements that began to appear much later, at the 90th cell generation following arsenite exposure. The increasing genomic instability was further characterized by an increased frequency of spontaneous mutations. Furthermore, the long-lasting genomic instability was related to elevated levels of reactive oxygen species (ROS), which at the 50th cell generation appeared higher than in stable parental cells. To gain additional insight into the continuing genomic instability, we examined several individual clones isolated at different time points from the growing cell population. Chromosomally and morphologically unstable cell clones, the number of which increased with the expanded growth, were also present at early phases of growth without arsenite. All genomically unstable clones exhibited higher ROS levels than untreated cells suggesting that oxidative stress is an important factor for the progression of genomic instability induced by arsenite.",
Arsenic,677643,"DNA-protein crosslinking by heavy metals in Novikoff hepatoma Abstract: Crosslinking of proteins to DNA was studied in live intact Novikoff ascites hepatoma cells exposed in vitro to salts of chromium VI, III, and II, nickel II, cadmium II, and to CoCl2, As2O3, and AlK(SO4)2. DNA-protein complexes were separated by high-speed centrifugation of cells solubilized in buffered 4% sodium dodecyl sulfate and assayed by polyacrylamide gel electrophoresis. Hexavalent chromium compounds formed DNA-protein complexes very efficiently. The trivalent, poorly soluble, cupric chromite was nearly as efficient crosslinker as hexavalent Cr, perhaps because phagocytosis facilitated its entry into the cells. The more basic divalent form produced hardly any crosslinks. Most of the crosslinked proteins were common to all of the chromium salts employed. Nickel salts formed DNA-protein crosslinks less efficiently. Most proteins crosslinked by this metal had a high molecular weight ranging from 94,000 to 200,000. There was little qualitative difference between the crosslinked protein patterns for several various nickel (II) salts. Similar results were obtained for cells incubated with cadmium salts. Most of the proteins crosslinked by cadmium had high molecular weights and were similar to those crosslinked by nickel (II). Relatively weak, but significant, Crosslinking was also observed when the Novikoff hepatoma cells were exposed to CoCl2, As2O3, or AlK(SO4)2.",
Arsenic,627034,"Role of HIF signaling on tumorigenesis in response to chronic low-dose arsenic administration Abstract: Trivalent inorganic arsenic (arsenite, arsenic trioxide, As(III)) is a primary contaminant of groundwater supplies worldwide. As(III), marketed as trisenox, is also an FDA-approved agent to treat cancer It has been previously shown by our laboratory that As(III) administered at doses lower than a therapeutic anticancer dose results in an increase in tumor formation and blood vessel density of tumors. In this work it was found that chronic administration of As(III) approaching the EPA action level of 10 ppb, given in the drinking water of mice 5 weeks prior to B16-F10 melanoma implantation, increased the growth rate of primary tumors and the number of metastases to the lung. Further, levels of arsenic in the tumor and lung were found to be much greater than those in the blood and similar to pro-angiogenic As(III) doses. Levels of hypoxia inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) surrounding the blood vessels in the tumors of the As(III)-treated mice were also found to be increased. Exposure of isolated B16-F10 tumor cells to chronic (3 or 7 day) but not acute (4 h) low-dose As(III) was found to increase HIF-1alpha expression and secretion of VEGF. Finally, coadministration of an inhibitor of HIF (YC-1) or a VEGFR-2 kinase inhibitor (SU5416) was found to antagonize the pro-angiogenic effects of low-dose As(III). Together, these results suggest that chronic exposure to low-dose As(III) could stimulate growth of tumors through a HIF-dependent stimulation of angiogenesis.",
Arsenic,1337714,"Genome-wide identification of rice class I metallothionein gene: Tissue expression patterns and induction in response to heavy metal stress Abstract: Metallothioneins (MTs) are members of a family of cysteine-rich low molecular weight polypeptides which play an important role in heavy metal detoxification and homeostasis of intracellular metal ions in plant. Though MT genes from some selected plants have been characterized with respect to their protein sequences, kinetic properties and tissue-specific localization, no detailed study has been carried out in rice. Here, we present genome-wide identification, structural and expression analyses of rice MT gene family. Our analysis suggests presence of 11 class I MT genes in rice genome (Release 7 of the MSU Rice Genome Annotation Project) which are differentially expressed during growth and development, in various tissues and during biotic and abiotic stresses. Our analyses suggest that class I MT proteins in rice differ in tissue localization as well as in heavy metal coordination chemistry. We also suggest that some MTs have a predominant role in detoxification of As (V) in arsenic-tolerant rice cultivars. Our analysis suggests that apart from transcriptional regulation, post-transcriptional alternative splicing in some members of this family takes place during growth and development, in various tissues and during biotic and abiotic stresses.",
Arsenic,2088473,"Trace metal contents of three tricalcium silicate materials; MTA Angelus, Micro Mega MTA, and Bioaggregate Abstract: <strong>AIM: </strong>To investigate the levels of nine metals (aluminium (Al), antimony (Sb), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), iron (Fe), lead (Pb), and molybdenum (Mo)) in MTA Angelus, Micro Mega MTA, and Bioaggregate using inductively coupled plasma-optical emission spectrometry (ICP-OES).<br /><br /><strong>METHODOLOGY: </strong>Each material (0.2 g) was digested using a mixture of hydrochloric and nitric acids and then filtered. The levels of nine metals in the resulting filtrates were measured by ICP-OES. The results were statistically analyzed using one-way ANOVA and the Bonferroni test.<br /><br /><strong>RESULTS: </strong>MTA Angelus contained more aluminium, beryllium, and chromium than Micro Mega MTA (p&lt;0.05), while their levels of arsenic, cadmium, and iron were similar. Antimony, lead, and molybdenum were not detected in any of the three tested cements. Bioaggregate contained trace amounts of aluminium.<br /><br /><strong>CONCLUSIONS: </strong>MTA Angelus and Micro Mega MTA contained small amounts of seven tested metal oxides. Bioaggregate only contained trace amounts of aluminium. This article is protected by copyright. All rights reserved.",
Arsenic,1016256,"Metal contents in the groundwater of Sahebgunj district, Jharkhand, India, with special reference to arsenic Abstract: A detailed study has been presented on groundwater metal contents of Sahebgunj district in the state of Jharkhand, India with special reference to arsenic. Both tubewell and well waters have been studied separately with greater emphasis on tubewell waters. Groundwaters of all the nine blocks of Sahebgunj district have been surveyed for iron, manganese, calcium, magnesium, copper and zinc in addition to arsenic. Normal distribution statistic, exploratory data analysis and robust Z-score analysis have been employed to find out the distribution pattern, localisation of data, outliers and other related information. Groundwaters of three blocks of Sahebgunj, namely, Sahebgunj, Rajmahal and Udhawa have been found to be alarmingly contaminated with arsenic present at or above 10 ppb. Arsenic distribution patterns in these blocks are highly asymmetric in nature with the common feature of increasing width from first to fourth quartile. A very broad fourth quartile in each case represents a long asymmetric tail on the right of the median. Tubewell waters of at least two more blocks require regular monitoring to identify the outbreak of arsenic at the onset. Groundwaters of Sahebgunj district in general contain high iron and manganese. It is by and large soft in nature. Well waters have been found to be better with regard to arsenic but iron and manganese contents do not vary significantly. Normal distribution analysis (NDA), box and whisker (BW) plot and Z-score analysis together can provide a reasonably complete statistical picture of metal contents in Sahebgunj district groundwaters.",
Arsenic,1380185,THE USE OF WHATMAN 41 FILTERS FOR PARTICLE COLLECTION Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM GAS COLLECTING COARSE-FRACTION AEROSOL ARSENIC SELENIUM ANTIMONY LOW TEMPERATURE,
Arsenic,1372612,"Geochemical conditions enhancing the solubilization of arsenic into groundwater in Japan Abstract: BIOSIS COPYRIGHT: BIOL ABS. The geochemical behavior of arsenic-bearing groundwaters from four areas Fukuoka, Kumamoto, Fukui, and Takatsuki has been reviewed and considered from the viewpoints of the chemical composition of the water, the geological setting of the host formation, and the arsenic content in sediments and rocks. In all the areas except Fukui, arsenic-bearing water is concluded to have come from a specific aquifer during water-sediment interactions. Stagnant groundwater, having reducing and alkaline properties, played a significant role in the release of arsenic from such Quaternary sediments as silt-clay layers and brownish-colored gravel beds.",
Arsenic,1508536,"Exogenous sodium nitroprusside alleviates arsenic-induced oxidative stress in wheat (Triticum aestivum L.) seedlings by enhancing antioxidant defense and glyoxalase system Abstract: The present study investigates the possible regulatory role of exogenous nitric oxide (NO) in mitigating oxidative stress in wheat seedlings exposed to arsenic (As). Seedlings were treated with NO donor (0.25 mM sodium nitroprusside, SNP) and As (0.25 and 0.5 mM Na(2)HAsO(4)·7H(2)O) separately and/or in combination and grown for 72 h. Relative water content (RWC) and chlorophyll (chl) content were decreased by As treatment but proline (Pro) content was increased. The ascorbate (AsA) content was decreased significantly with increased As concentration. The imposition of As caused marked increase in the MDA and H(2)O(2) content. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) significantly increased with an increase in the level of As (both 0.25 and 0.5 mM), while the GSH/GSSG ratio decreased at higher concentration (0.5 mM). The ascorbate peroxidase and glutathione S-transferase activities consistently increased with an increase in the As concentration, while glutathione reductase (GR) activities increased only at 0.25 mM. The monodehydroascorbate reductase (MDHAR) and catalase (CAT) activities were not changed upon exposure to As. The activities of dehydroascorbate reductase (DHAR) and glyoxalase I (Gly I) decreased at any levels of As, while glutathione peroxidase (GPX) and glyoxalase II (Gly II) activities decreased only upon 0.5 mM As. Exogenous NO alone had little influence on the non-enzymatic and enzymatic components compared to the control seedlings. These inhibitory effects of As were markedly recovered by supplementation with SNP; that is, the treatment with SNP increased the RWC, chl and Pro contents; AsA and GSH contents and the GSH/GSSG ratio as well as the activities of MDHAR, DHAR, GR, GPX, CAT, Gly I and Gly II in the seedlings subjected to As stress. These results suggest that the exogenous application of NO rendered the plants more tolerant to As-induced oxidative damage by enhancing their antioxidant defense and glyoxalase system.",
Arsenic,1019778,"Human biomonitoring of arsenic and antimony in case of an elevated geogenic exposure Abstract: Part of the northern Palatinate region in Germany is characterized by elevated levels of arsenic and antimony in the soil due to the presence of ore sources and former mining activities. In a biomonitoring study, 218 residents were investigated for a putative increased intake of these elements. Seventy-six nonexposed subjects in a rural region in south lower Saxony were chosen as the reference group. Urine and scalp hair samples were obtained as surrogates to determine the internal exposures to arsenic and antimony. The analyses were performed using graphite furnace atomic absorption spectrometry except for arsenic in urine, which was determined by the hydride technique. This method does not detect organoarsenicals from seafood, which are not toxicologically relevant. In the northern Palatinate subjects, slightly elevated arsenic contents in urine and scalp hair (presumably not hazardous) could be correlated with an increased arsenic content in the soil. On the other hand, the results did not show a correlation between the antimony contents in the soil of the housing area and those in urine and hair. Except for antimony in scalp hair, age tended to be associated with internal exposures to arsenic and antimony in both study groups. Consumption of seafood had a slight impact on the level of urinary arsenic, which is indicative of the presence of low quantities of inorganic arsenicals and dimethylarsinic acid in seafood. The arsenic and antimony contents in scalp hair were positively correlated with the 24-hr arsenic excretion in urine. However, antimony in scalp hair was not correlated with seafood consumption as was arsenic in scalp hair and in urine. This indicated the existence of unidentified common pathways of exposure contributing to the alimentary body burden. Short time peaks in the 24-hr excretion of arsenic in urine, which could not be assigned to a high consumption of seafood, were detected for six study participants. This suggests that additional factors relevant in the exposure to arsenic are still unidentified.",
Arsenic,1597333,"Exposure to As, Cd and Pb-mixture impairs myelin and axon development in rat brain, optic nerve and retina Abstract: Arsenic (As), lead (Pb) and cadmium (Cd) are the major metal contaminants of ground water in India. We have reported the toxic effect of their mixture (metal mixture, MM), at human relevant doses, on developing rat astrocytes. Astrocyte damage has been shown to be associated with myelin disintegration in CNS. We, therefore, hypothesized that the MM would perturb myelinating white matter in cerebral cortex, optic nerve (O.N.) and retina. We observed modulation in the levels of myelin and axon proteins, such as myelin basic protein (MBP), proteolipid protein, 2'-, 3'-cyclic-nucleotide-3'-phosphodiesterase, myelin-associated glycoprotein and neurofilament (NF) in the brain of developing rats. Dose and time-dependent synergistic toxic effect was noted. The MBP- and NF-immunolabeling, as well as luxol-fast blue (LFB) staining demonstrated a reduction in the area of intact myelin-fiber, and an increase in vacuolated axons, especially in the corpus-callosum. Transmission electron microscopy (TEM) of O.N. revealed a reduction in myelin thickness and axon-density. The immunolabeling with MBP, NF, and LFB staining in O.N. supported the TEM data. The hematoxylin and eosin staining of retina displayed a decrease in the thickness of nerve-fiber, plexiform-layer, and retinal ganglion cell (RGC) count. Investigating the mechanism revealed a loss in glutamine synthetase activity in the cerebral cortex and O.N., and a fall in the brain derived neurotrophic factor in retina. An enhanced apoptosis in MBP, NF and Brn3b-containing cells justified the diminution in myelinating axons in CNS. Our findings for the first time indicate white matter damage by MM, which may have significance in neurodevelopmental-pediatrics, neurotoxicology and retinal-cell biology.",
Arsenic,1597389,Removal of Arsenic from Aqueous Solution by Fe(III)-Impregnated Sorbent Prepared from Sugarcane Bagasse Abstract: ,
Arsenic,1353036,"Arsenolipids in marine oils and fats: A review of occurrence, chemistry and future research needs Abstract: ",
Arsenic,1019606,"Biological monitoring of occupational exposure to arsenic by determining urinary content of inorganic arsenic and its methylated metabolites Abstract: A study was undertaken to assess the relationship between inhalation exposure to arsenic in copper smeltery workers and urinary excretion of total inorganic arsenic metabolites (Asitm), including inorganic arsenic (Asi), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The methods applied made it possible, in principle, to determine all forms of airborne arsenic and to eliminate the influence of seafood-derived organoarsenicals on the level of urinary Asitm. Air samples were collected on the second day of work after the weekend break. Urine samples were collected just after shift-end on the same workday. The time-weighted average (TWA) concentrations of arsenic in the workers' breathing zone varied between 1 and 746 microg/m3 and Asitm concentrations in urine between 2 and 850 microg/l (s.g. 1.024). The urine samples with a specific gravity of lower than 1.010 and higher than 1.030 were not considered; neither were those subjects with an Asitm excretion efficiency of higher than 100% of the dose absorbed during the day of measurement. In total, 53 air samples and corresponding urine samples were obtained. The correlation coefficient between the airborne arsenic concentration in microg/m3 (X) and the concentration of urinary Asitm in microg/l, s.g. 1.024 (Y), was 0.723. The relation between the two variables can be presented using the following formula: Y = 6.29 x X0.616. According to the findings of this study, as well as the results of three other studies based on similar principles, the daily exposure to arsenic concentrations of 10 microg/m3 and 50 microg/m3 led to concentrations of Asitm in urine of about 30 microg/l and 70 microg/l (s.g. 1.024), respectively.",
Arsenic,1519036,"Low-dose arsenic induces chemotherapy protection via p53/NF-?B-mediated metabolic regulation Abstract: Most chemotherapeutical drugs kill cancer cells chiefly by inducing DNA damage, which unfortunately also causes undesirable injuries to normal tissues, mainly due to p53 activation. We report a novel strategy of normal tissue protection that involves p53/NF-?B coordinated metabolic regulation. Pretreatment of untransformed cells with low doses of arsenic induced concerted p53 suppression and NF-?B activation, which elicited a marked induction of glycolysis. Significantly, this metabolic shift provided cells effective protection against cytotoxic chemotherapy, coupling the metabolic pathway to cellular resistance. Using both in vitro and in vivo models, we demonstrated an absolute requirement of functional p53 in arsenic-mediated protection. Consistently, a brief arsenic pretreatment selectively protected only normal tissues, but not tumors, from toxicity of chemotherapy. An indispensable role of glycolysis in protecting normal tissues was demonstrated by using an inhibitor of glycolysis, 2-deoxyglucose, which almost totally abolished low-dose arsenic-mediated protection. Together, our work demonstrates that low-dose arsenic renders normal cells and tissues resistant to chemotherapy-induced toxicity by inducting glycolysis.",
Arsenic,1337465,"Influence of Zn(II) on the adsorption of arsenate onto ferrihydrite Abstract: Addition of iron oxide to arsenic-contaminated soil has been proposed as a means of reducing the mobility of arsenic in the soil. Arsenic and zinc are common coexisting contaminants in soils. The presence of zinc therefore may affect the adsorption properties of arsenic on iron oxide, and may thus affect its mobility in the soil. The influence of Zn(II) on the adsorption of arsenate ions on iron oxide was studied. Batch adsorption experiments indicated that Zn(II) increased the arsenate removal from a solution by ferrihydrite at pH 8. However, ATR-FTIR spectroscopy showed that no adsorption of arsenate on a ferrihydrite film occurred at pD 8 in the presence of Zn(II). Precipitation of zinc hydroxide carbonate followed by arsenate adorption onto the precipitate was found to be a plausible mechanism explaining the arsenate removal from a solution in the presence of Zn(II) at pH/pD 8. The previously suggested mechanisms attributing the enhanced removal of arsenate from solution in the presence of Zn(II) to additional adsorption on iron oxides could not be verified under the experimental conditions studied. It was also shown that at pH/pD 4, the presence of Zn(II) in the system did not significantly affect the adsorption of arsenate on ferrihydrite.",
Arsenic,380759,"Chronic exposure to cadmium and arsenic strongly influences concentrations of 8-oxo-7,8-dihydro-2'-deoxyguanosine in urine Abstract: Exposure to arsenic (As), cadmium (Cd) and lead (Pb) may generate oxidative stress, which can be assessed by 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in urine, a sensitive marker of oxidatively damaged DNA. We have evaluated oxidative stress induced by mixed chronic exposure to As, Cd, Pb, as well as the influence of As metabolism and nutritional status, i.e. ferritin (Ft), selenium (Se), zinc (Zn), manganese (Mn) and body weight. 8-oxodG was measured in urine from 212 women in early pregnancy from Matlab, rural Bangladesh, using LC-MS/MS. Cd and Pb were analyzed in urine and erythrocytes, while Se, Mn and Zn were analyzed in erythrocytes, all by ICPMS. As and As metabolites were analyzed in urine by HPLC-ICPMS. Ferritin was analyzed in plasma by radioimmunoassay. Median concentration of 8-oxodG was 8.3 nmol/L (adjusted for specific gravity), range 1.2-43, corresponding to a median of 4.7 mug/g creatinine, range 1.8-32. 8-oxodG was positively associated with urinary Cd (ss=0.32, p<0.001), urinary As (ss=0.0007, p=0.001), fraction of the monomethylated arsenic metabolite (MMA) in urine (ss=0.0026, p=0.004) and plasma Ft (ss = 0.20, p<0.001). A joint effect was seen for U-Cd and U-As, but whether this effect was additive or multiplicative was difficult to discern.",
Arsenic,1016561,"Purification and characterization of thiols in an arsenic hyperaccumulator under arsenic exposure Abstract: Pteris vittata (Chinese brake fern) is the first reported arsenic hyperaccumulator. To investigate the arsenic tolerance mechanism in this plant, reversed-phase HPLC with postcolumn derivatization was used to analyze the thiols induced under arsenic exposure. A major thiol in the plant leaflets was found to be responsive to arsenic exposure. The arsenic-induced compound was purified on a large scale by combining covalent chromatography and preparative reversed-phase HPLC. About 2 mg of this compound was isolated from 1 kg of fresh leaflets. The purified arsenic-induced compound was characterized using electrospray ionization mass spectrometry. A molecular ion (M + 1) of 540 and fragments were obtained, which indicated that the arsenic-induced thiol was a phytochelatin with two subunits (PC(2)). Compared to the classical methods for purification of phytochelatins, this new method is more specific, simple, and rapid and is suitable for purification of PCs in a large scale as well as sample preparation for mass spectrometry analysis.",
Arsenic,1704109,"Dimethylphosphinato and dimethylarsinato complexes of group 13 metals and their chemistry Abstract: Dimethylphosphinato M(Me2PO2)3 and dimethylarsinato (cacodylato) M(Me2AsO2)3 complexes of group 13 metals (M=Al, Ga, In, Tl) have been prepared in good yields from dimethylphosphinic and dimethylarsinic acids or sodium dimethylarsinate. The phosphinato and the gallium and indium cacodylato complexes are most likely polymeric, while the aluminum and thallium cacodylato ones are monomeric based on their thermal behavior. From aqueous solutions the hydrated complexes Al(Me2PO2)3·3H2O, Ga(Me2PO2)3·H2O, Al(Me2AsO2)3·H2O, and In(Me2AsO2)3·3H2O were isolated. Pyridine does not form addition compounds with any phosphinato and cacodylato complexes, In(Me2AsO2)3 was rearranged, and Al(Me2AsO2)3 gave Al(Me2AsO2)2(OH). The NMR spectra of the cacodylato complexes in D2O, CD3OD, and CDCl3 revealed the existence of several species in solution. All cacodylato complexes were decomposed by thiols, e.g., cysteine giving cystine and Me2As-SCH2CH(NH3 +)COO?.",
Arsenic,1024425,"Synchrotron photoemission analysis of semiconductor/electrolyte interfaces by the frozen-electrolyte approach: Interaction of HCl in 2-propanol with GaAs(100) Abstract: Perspectives of a new approach for the synchrotron photoemission spectroscopic analysis of chemical processes at solid/liquid interfaces under UHV conditions have been explored. A thin layer of HCl-2-propanol solution was frozen-in on the semiconductor GaAs(100) wafer surface by cooling the substrate to liquid nitrogen temperature after etching off the native oxide layer under N2 atmosphere. Chemical reactions induced in situ by exposure to synchrotron radiation (SR) and by stepwise heating have been monitored. Right after etching and freezing, the surface is covered by gallium chlorides with 1, 2, 3, and 4 Cl ions attached and lattice back-bonded to As atoms, as well as by elemental arsenic As0 and 2-propanol. Exposure to SR at low temperature produces surface As chlorides at the expense of As0. The GaCl3 and GaCl2 emissions diminish while GaCl is enhanced. On the other hand, heating the sample to approximately 130 K just above H2O desorption causes the thermodynamically expected reaction of AsCl3 with the substrate GaAs to form Ga chloride species and As0. Heating the sample to room temperature leaves only As0 on the surface and for gallium the content of all surface chlorides is drastically reduced. By further heating to 400 K elemental arsenic starts to desorb and the Ga chloride surface content is reduced. Using different excitation energies the depth composition of the reaction products has been monitored indicating a tendency of decreasing chlorination numbers and increasing Ga vs As chloride content toward the pristine substrate at each stage of the reaction.",
Arsenic,1017354,"Protective effects of plasma alpha-tocopherols on the risk of inorganic arsenic-related urothelial carcinoma Abstract: Arsenic plays an important role in producing oxidative stress in cultured cells. To investigate the interaction between high oxidative stress and low arsenic methylation capacity on arsenic carcinogenesis, a case-control study was conducted to evaluate the relationship among the indices of oxidative stress, such as urinary 8-hydroxydeoxyquanine (8-OHdG), as well as plasma micronutrients and urinary arsenic profiles on urothelial carcinoma (UC) risk. Urinary 8-OHdG was measured using high-sensitivity enzyme-linked immunosorbent assay kits. The urinary arsenic species were analyzed using high-performance liquid chromatography and hydride generator-atomic absorption spectrometry. Plasma micronutrient levels were analyzed using reversed-phase high-performance liquid chromatography. The present study showed a significant protective effect of plasma alpha-tocopherol on UC risk. Plasma alpha-tocopherol levels were significantly inversely related to urinary total arsenic concentrations and inorganic arsenic percentage (InAs%), and significantly positively related to dimethylarsinic acid percentage (DMA%). There were no correlations between plasma micronutrients and urinary 8-OHdG. Study participants with lower alpha-tocopherol and higher urinary total arsenic, higher InAs%, higher MMA%, and lower DMA% had a higher UC risk than those with higher alpha-tocopherol and lower urinary total arsenic, lower InAs%, lower MMA%, and higher DMA%. These results suggest that plasma alpha-tocopherol might modify the risk of inorganic arsenic-related UC.",
Arsenic,1345919,ARSENIC KERATOSES AND MORBUS BOWEN Abstract: ,
Arsenic,1519042,"Characteristics and distribution of analyzed metals in soil profiles in the vicinity of a postflotation waste site in the Bukowno region, Poland Abstract: The lead-zinc industry in the Bukowno region of southern Poland has polluted the surface layer of the surrounding soils mainly with lead (Pb), cadmium (Cd), zinc (Zn), arsenic (As), and thallium (Tl). Analysis of six soil profiles, taken on the east side of the postflotation waste site of the Mining and Metallurgical Plants ZGH &quot;Boles?aw&quot; in Bukowno, showed that they were podzol soils, taking form of loose sands with neutral pH and reducing conditions. Concentration of organic matter in the horizons ranged from 2 to 80 %. The main components of the mineral soil were quartz, carbonates, K-feldspars, plagioclases, and micas (sericite). The highest total concentrations of metals were found in the O, A, and B horizons. Over 90 % of the Cd content, 80 % of the Pb content, 60 % of the Zn content, ?60 % of the Tl content, and 20 % of the As content occurred as mobile forms. The corresponding total concentrations were 10 mg/kg Cd, 922 mg/kg Pb, 694 mg/kg Zn, &lt;1 mg/kg Tl, and &lt;5 mg/kg As. This can potentially be taken up from the soil and transported in the trophic chain. Comparing the total metal content with the legal limits in Poland, it is observed, that the investigated soils exceeded the permissible levels of Cd, Pb, and Zn for agricultural soils. Arsenic and Tl are not reflected in the chemical quality of soil classifications.",
Arsenic,1019109,"Arsenite induces p53 accumulation through an ATM-dependent pathway in human fibroblasts Abstract: Arsenic compounds are potent human carcinogens. Accumulated evidence has shown that arsenite-induced cytogenetic alterations are associated with the carcinogenicity of arsenic. Because p53 plays a guarding role in maintaining genome integrity and accuracy of chromosome segregation, the mechanistic effects of arsenite on p53 activation were analyzed. In the present study, arsenite-induced DNA strand breaks were confirmed by alkaline single-cell gel electrophoresis (comet assay) in human fibroblast (HFW) cells. Accompanying the appearance of DNA strand breaks was a significant accumulation of p53 in arsenite-treated HFW cells, as demonstrated by immunoblotting and immunofluorescence techniques. p53 downstream proteins, such as p21 and the human homologue of murine double minute-2, were also significantly induced by arsenite treatment. Cell cycle retardation and G2-M arrest were observed in 5-bromo-2'-deoxyuridine pulse-labeled HFW cells by flow cytometry. Wortmannin, an inhibitor of phosphatidylinositol 3-kinases, inhibited arsenite- or X-ray irradiation-induced p53 accumulation but did not alter UV irradiation- or N-acetyl-Leu-Leu-norleucinal-induced p53 accumulation. p53 phosphorylation on serine 15 was also confirmed by immunoblotting technique in arsenite- and X-ray-treated HFW cells but was not observed in UV- or N-acetyl-Leu-Leu-norleucinal-treated HFW cells. These results suggest the involvement of a phosphatidylinositol 3-kinase-related protein kinase in arsenite-induced p53 accumulation. For confirmation, we demonstrated that arsenite treatment, similar to X-ray irradiation, did not induce p53 accumulation in GM3395 fibroblasts derived from a patient with ataxia telangiectasia. In contrast, UV irradiation did cause p53 accumulation in these cells. Together, these findings infer that arsenite-induced DNA strand breaks may lead to p53 phosphorylation and accumulation through an ataxia telangiectasia mutated-dependent pathway in HFW cells.",
Arsenic,1031839,"Biological monitoring of arsenic exposure of gallium arsenide- and inorganic arsenic-exposed workers by determination of inorganic arsenic and its metabolites in urine and hair Abstract: In an attempt to establish a method for biological monitoring of inorganic arsenic exposure, the chemical species of arsenic were measured in the urine and hair of gallium arsenide (GaAs) plant and copper smelter workers. Determination of urinary inorganic arsenic concentration proved sensitive enough to monitor the low-level inorganic arsenic exposure of the GaAs plant workers. The urinary inorganic arsenic concentration in the copper smelter workers was far higher than that of a control group and was associated with high urinary concentrations of the inorganic arsenic metabolites, methylarsonic acid (MAA) and dimethylarsinic acid (DMAA). The results established a method for exposure level-dependent biological monitoring of inorganic arsenic exposure. Low-level exposures could be monitored only by determining urinary inorganic arsenic concentration. High-level exposures clearly produced an increased urinary inorganic arsenic concentration, with an increased sum of urinary concentrations of inorganic arsenic and its metabolites (inorganic arsenic + MAA + DMAA). The determination of urinary arsenobetaine proved to determine specifically the seafood-derived arsenic, allowing this arsenic to be distinguished clearly from the arsenic from occupational exposure. Monitoring arsenic exposure by determining the arsenic in the hair appeared to be of value only when used for environmental monitoring of arsenic contamination rather than for biological monitoring.",
Arsenic,1368900,"Induction in mouse peritoneal macrophages of 34 kDa stress protein and heme oxygenase by sulfhydryl-reactive agents Abstract: The synthesis of 34-kDa stress protein was enhanced, with a simultaneous increase in heme oxygenase activity, when mouse macrophages were exposed to diethylmaleate or sodium arsenite. After 7 h of exposure to the sulfhydryl agents, the 34-kDa protein was the most actively synthesized protein. Immunoblot analysis showed that the induced 34-kDa protein reacted with an antibody raised against bovine heme oxygenase. Cadmium ions or 1-chloro-2,4-dinitrobenzene also induced the 34-kDa protein which reacted with the antibody. Treatments of the cells with buthionine sulfoximine or hydrogen peroxide weakly induced the protein, while diamide treatment or heat shock was without effect. These results are consistent with our previous findings that heavy metal ions including arsenite and cadmium ions induce heme oxygenase (32-kDa stress protein) in human cell lines [Taketani, S., Kohno, H., Yoshinaga, T., &amp; Tokunaga, R. (1989) FEBS Lett. 245, 173-176], and also suggest that the formation of glutathione conjugate with sulfhydryl-reactive agents may mediate the induction of the stress protein in mouse peritoneal macrophages.",
Arsenic,1021507,"Neuroprotective efficacy of curcumin in arsenic induced cholinergic dysfunctions in rats Abstract: Our recent studies have shown that curcumin protects arsenic induced neurotoxicity by modulating oxidative stress, neurotransmitter levels and dopaminergic system in rats. As chronic exposure to arsenic has been associated with cognitive deficits in humans, the present study has been carried out to implore the neuroprotective potential of curcumin in arsenic induced cholinergic dysfunctions in rats. Rats treated with arsenic (sodium arsenite, 20mg/kg body weight, p.o., 28 days) exhibited a significant decrease in the learning activity, assessed by passive avoidance response associated with decreased binding of (3)H-QNB, known to label muscarinic-cholinergic receptors in hippocampus (54%) and frontal cortex (27%) as compared to controls. Decrease in the activity of acetylcholinesterase in hippocampus (46%) and frontal cortex (33%), staining of Nissl body, immunoreactivity of choline acetyltransferase (ChAT) and expression of ChAT protein in hippocampal region was also observed in arsenic treated rats as compared to controls. Simultaneous treatment with arsenic and curcumin (100mg/kg body weight, p.o., 28 days) increased learning and memory performance associated with increased binding of (3)H-QNB in hippocampus (54%), frontal cortex (25%) and activity of acetylcholinesterase in hippocampus (41%) and frontal cortex (29%) as compared to arsenic treated rats. Increase in the expression of ChAT protein, immunoreactivity of ChAT and staining of Nissl body in hippocampal region was also observed in rats simultaneously treated with arsenic and curcumin as compared to those treated with arsenic alone. The results of the present study suggest that curcumin significantly modulates arsenic induced cholinergic dysfunctions in brain and also exhibits neuroprotective efficacy of curcumin.",
Arsenic,582034,"Use of the Rey-Osterrieth Complex Figure Test for neurotoxicity evaluation of mixtures in children Abstract: The aim of this study was to assess the value of the children's version of the Rey-Osterrieth Complex Figure Test as a screening test in a population exposed to different mixtures of neurotoxicants. Copy and Immediate Recall scores were evaluated through the test. Children were recruited from three sites; an area with natural contamination by fluoride and arsenic (F-As), a mining-metallurgical area with lead and arsenic contamination (Pb-As) and a malaria zone with the evidence of fish contaminated with dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs). Children aged 6-11 years old, living in one of the three polluted sites since birth were recruited (n = 166). The exposure was evaluated as follows: fluoride and arsenic in urine, lead in blood and DDT, dichlorodiphenyldichloroethylene (DDE) and PCBs in serum. To evaluate the test performance, z-scores for Copy and Immediate Recall were calculated. The proportion of children by residence area with performance lower than expected by age (below -1 SD) for Copy and Immediate Recall was in the F-As area (88.7% and 59%) and in the DDT-PCBs area (73% and 43.8%), respectively. In the Pb-As area, the proportion was 62% for both tests. After adjustment, Copy correlated inversely with fluoride in urine (r = -0.29; p < 0.001) and Immediate Recall correlated inversely with fluoride in urine (r = -0.27; p < 0.05), lead in blood (r = -0.72; p < 0.01), arsenic in urine (r = -0.63; p < 0.05) and DDE (r = -0.25; p < 0.05). This study provided evidence that children included in this research are living in high risk areas and were exposed to neurotoxicants. Poor performance in the test could be explained in some way by F, Pb, As or DDE exposure, however social factors or the low quality of school education prevalent in the areas could be playing an important role.",
Arsenic,1021591,"Occupational exposure to metal compounds and lung cancer. Results from a multi-center case-control study in Central/Eastern Europe and UK Abstract: <strong>PURPOSE: </strong>To study the association between occupational exposure to metals including chromium, cadmium, nickel, and arsenic compounds, within a population-based study design, while adjusting for confounding factors.<br /><br /><strong>METHODS: </strong>A population-based lung cancer case-control study in Central/Eastern Europe and UK was conducted in 1998-2003, including 2,853 cases and 3,104 controls. Exposure to 70 occupational agents was assessed by local expert-teams for all subjects. Odds ratios (OR) for exposure to dust and fumes/mist of chromium, nickel, cadmium, arsenic, as well as inorganic pigment dust and inorganic acid mist, were adjusting for smoking, age, center, sex, and exposure to other occupational agents including the metals under study.<br /><br /><strong>RESULTS: </strong>Exposure to arsenic (prevalence = 1.4%) was associated with an increased lung cancer risk ((OR) 1.65, 95% confidence interval (95% CI):1.05-2.58). For chromium dust (prevalence = 4.8%, OR: 1.25, 95% CI: 0.95-1.65), a linear upward trend for duration and cumulative exposure was observed. A weak association was observed for exposure to cadmium fumes (prevalence = 1.8%, OR: 1.19, 95% CI: 0.77-1.82), which was strongest for the highest category of cumulative exposure (OR: 2.04, 95% CI: 1.07-3.90). No increased risk was observed for inorganic acid mist, inorganic pigment dust, or nickel, after adjustment for other metals. An independent effect of nickel cannot be excluded, due to its collinearity with chromium exposure.<br /><br /><strong>CONCLUSIONS: </strong>Occupational exposure to metals is an important risk factor for lung cancer. Although the strongest risk was observed for arsenic, exposure to chromium dust was most important in terms of attributable risk due to its high prevalence.",
Arsenic,1033150,"Cytological changes occurring in the liver of coturnix quail with an acute arsenic exposure Abstract: Coturnix quail (Coturnix coturnix) were given acute oral doses of sodium arsenite (NaAsO2). On each of two successive days they received 1 mg sodium arsenite, followed by 3 mg on the third day. There was no observable difference between the arsenic-exposed quail liver and the controls at the light microscope level; however, swelling of granular endoplasmic reticulum (GER) in the hepatocytes of the arsenic-exposed quail was detected with electron microscopy. The swollen organelles were determined to be GER by their peripheral orientation around the mitochondria and the ribosomes attached to their cytoplasm-exposed membrane surfaces. The degree of swelling ranged from slight to severe, and was due to an osmotic imbalance possibly brought about by the indirect inhibition of the sodium pump by arsenic.",
Arsenic,2345720,"Risk of leukemia in relation to exposure to ambient air toxics in pregnancy and early childhood Abstract: There are few established causes of leukemia, the most common type of cancer in children. Studies in adults suggest a role for specific environmental agents, but little is known about any effect from exposures in pregnancy to toxics in ambient air. In our case-control study, we ascertained 69 cases of acute lymphoblastic leukemia (ALL) and 46 cases of acute myeloid leukemia (AML) from California Cancer Registry records of children &lt;age 6, and 19,209 controls from California birth records within 2km (1.3 miles) (ALL) and 6km (3.8 miles) (AML) of an air toxics monitoring station between 1990 and 2007. Information on air toxics exposures was taken from community air monitors. We used logistic regression to estimate the risk of leukemia associated with one interquartile range increase in air toxic exposure. Risk of ALL was elevated with 3(rd) trimester exposure to polycyclic aromatic hydrocarbons (OR=1.16, 95% CI 1.04, 1.29), arsenic (OR=1.33, 95% CI 1.02, 1.73), benzene (OR=1.50, 95% CI 1.08, 2.09), and three other toxics related to fuel combustion. Risk of AML was increased with 3rd trimester exposure to chloroform (OR=1.30, 95% CI 1.00, 1.69), benzene (1.75, 95% CI 1.04, 2.93), and two other traffic-related toxics. During the child's first year, exposure to butadiene, ortho-xylene, and toluene increased risk for AML and exposure to selenium increased risk for ALL. Benzene is an established cause of leukemia in adults; this study supports that ambient exposures to this and other chemicals in pregnancy and early life may also increase leukemia risk in children.",
Arsenic,1016216,"Can lung cancer risk among nickel refinery workers be explained by occupational exposures other than nickel? Abstract: <strong>BACKGROUND: </strong>Exposures in nickel refineries represent complex chemical mixtures, but only the effect of nickel has been evaluated quantitatively in epidemiologic studies of nickel workers.<br /><br /><strong>METHODS: </strong>For a Norwegian refinery, time- and department-specific exposure estimates were developed for arsenic, sulfuric acid mists, and cobalt in air on the basis of personal measurements and chemical data on raw materials and process intermediates. Exposure to asbestos, as well as employment in high-risk occupations outside the refinery, were assessed. We conducted a case-control study nested in a cohort of refinery workers, with 213 cases (diagnosed 1952-1995) and 525 age-matched controls. We analyzed lung cancer risk, adjusted for smoking, by cumulative exposure and duration of work.<br /><br /><strong>RESULTS: </strong>There was a substantial association between cumulative exposure to water-soluble nickel and lung cancer risk. Weaker effects were suggested for exposure to arsenic at the refinery and for occupational exposures outside the refinery for 15 years or more. No detectable excess risk was found for refinery exposure to asbestos or sulfuric acid mists, and no dose-related increase in risk was seen from cobalt.<br /><br /><strong>CONCLUSIONS: </strong>Exposure to water-soluble nickel remained the most likely explanation for the excess lung cancer risk in the cohort. Other occupational exposures did not confound the strong dose-related effect of nickel to any appreciable degree.",
Arsenic,1340005,"Altered expression profiles of microRNAs upon arsenic exposure of human umbilical vein endothelial cells Abstract: Recent studies in our laboratory indicated that arsenite at 20?M significantly induces the apoptosis of HUVECs. In this study we analyzed miRNAs expression profiles upon arsenic exposure of these cells to explore the molecular mechanisms of arsenic-induced vascular toxicity. The expression of miRNAs was examined by Exiqon miRCURY™ LNA microRNA chips. We found that 85 miRNAs were up-regulated and 52 were down-regulated by arsenic treatment as compared to the control group. The expression of altered miRNAs was validated by quantitative reverse-transcription PCR (qRT-PCR). A number of DNA motifs were identified in the promoters of the perturbed miRNAs by promoter analysis using MEME software. Analysis of cellular functions by using DAVID Bioinformatics Resources revealed that phosphoproteins and genes involved in alternative splicing are among the top categories targeted by both up- and down-regulated miRNAs. In conclusion, the results show that the alteration of miRNAs expression might play crucial roles in arsenic-induced vascular injury.",
Arsenic,1019812,"Porphyrins as early biomarkers for arsenic exposure in animals and humans Abstract: We studied the effect of arsenic exposure on the haem biosynthetic pathway in the rat and humans. Significant increases in protoporphyrin IX, coproporphyrin III, coproporphyrin I were observed in the blood, liver and kidney, and in the urine of rats after a single dose of arsenic. The level of increase was dependent on the arsenic species present. Most of porphyrin concentrations in the tissues increased within 24 hr and urinary excretion elevated within 48 hr. In the human study, we collected urine samples from 113 people who live in Xing Ren of Guizhou Province, a coal-borne arsenicosis endemic area in southwest of PR China and from 30 people who live in Xing Yi (about 80 km southwest of Xing Ren) where arsenicosis is not prevalent. We analyzed the urinary porphyrins using HPLC. Results indicate that all urinary porphyrins were higher in the arsenic exposed group than those in the control group. Women, children and older age people spend much of their time indoors, they had greater increases of urinary arsenic and porphyrins. They were the higher risk groups among the study subjects. A positive correlation between the urinary arsenic levels and porphyrin concentrations demonstrated the effect of arsenic on haem biosynthesis. Significant alteration in the porphyrin excretion profiles of the younger age (&lt;20 y) arsenic exposed group suggested that porphyrins could be used as early warning biomarkers for chronic exposure to arsenic.",
Arsenic,627917,"Arsenic induces apoptosis in mouse liver is mitochondria dependent and is abrogated by N-acetylcysteine Abstract: Arsenicosis, caused by arsenic contamination of drinking water supplies, is a major public health problem in India and Bangladesh. Chronic liver disease, often with portal hypertension occurs in chronic arsenicosis, contributes to the morbidity and mortality. The early cellular events that initiate liver cell injury due to arsenicosis have not been studied. Our aim was to identify the possible mechanisms related to arsenic-induced liver injury in mice. Liver injury was induced in mice by arsenic treatment. The liver was used for mitochondrial oxidative stress, mitochondrial permeability transition (MPT). Evidence of apoptosis was sought by TUNEL test, caspase assay and histology. Pretreatment with N-acetyl-L-cysteine (NAC) was done to modulate hepatic GSH level. Arsenic treatment in mice caused liver injury associated with increased oxidative stress in liver mitochondria and alteration of MPT. Altered MPT facilitated cytochrome c release in the cytosol, activation of caspase 9 and caspase 3 activities and apoptotic cell death. Pretreatment of NAC to arsenic-treated mice abrogated all these alteration suggesting a glutathione (GSH)-dependent mechanism. Oxidative stress in mitochondria and inappropriate MPT are important in the pathogenesis of arsenic induced apoptotic liver cell injury. The phenomenon is GSH dependent and supplementation of NAC might have beneficial effects.",
Arsenic,736726,"Murshidabad--One of the nine groundwater arsenic-affected districts of West Bengal, India. Part II: Dermatological, neurological, and obstetric findings Abstract: INTRODUCTION: To understand the severity of related health effects of chronic arsenic exposure in West Bengal, a detailed 3-year study was carried out in Murshidabad, one of the nine arsenic-affected districts in West Bengal. METHODS: We screened 25,274 people from 139 arsenic-affected villages in Murshidabad to identify patients suffering from chronic arsenic toxicity for evidence of multisystemic features and collected biological samples such as head hair, nail, and spot urine from the patients along with the tubewell water they were consuming. RESULTS: Out of 25,274 people screened, 4813 (19%) were registered with arsenical skin lesions. A case series involving arsenical skin lesions resulting in cancer and gangrene were noted during this study. Representative histopathological pictures of skin biopsy of different types of lesions were also presented. Out of 2595 children we examined for arsenical skin lesions, 122 (4%) were registered with arsenical skin lesions, melanosis with or without keratosis. Different clinical and electrophysiological neurological features were noticed among the arsenic-affected villagers. Both the arsenic content in the drinking water and duration of exposure may be responsible in increasing the susceptibility of pregnant women to spontaneous abortions, stillbirths, preterm births, low birth weights, and neonatal deaths. Some additional multisystemic features such as weakness and lethargy, chronic respiratory problems, gastrointestinal symptoms, and anemia were also recorded in the affected population. DISCUSSION: The findings from this survey on different health effects of arsenic exposure were compared to those from previous studies carried out on arsenic-affected populations in India and Bangladesh as well as other affected countries. CONCLUSION: Multisystemic disorders, including dermal effects, neurological complications, and adverse obstetric outcomes, were observed to be associated with chronic arsenic exposure in the study population in Murshidabad, West Bengal. The magnitude of severity was related to the concentration of arsenic in water as well as duration of the exposure.",
Arsenic,1171870,"Effect of cysteine on the speciation of arsenic by using hydride generation atomic absorption spectrometry Abstract: The effect of cysteine and related compounds on the speciation of arsenic (7440382) using hydride generation techniques was investigated. Arsenic was determined in human urine samples by a method using flow injection, hydride generation, and atomic absorption spectrometry; 2% cysteine was added to samples prior to hydride generation in order to eliminate errors due to the pH dependence of hydride generation techniques for arsenic species. A mechanism was proposed whereby arsenic species in the arsenic(V) state were reduced to the arsenic(III) state as organosulfur arsenic(III) compounds via reaction with the thiol; these products reacted with tetrahydroborate(III) under similar conditions to yield arsines without interference from cysteine. Nonthiol containing amino acids did not react with arsenic species in such a way, and therefore did not affect the pH dependence of arsenic hydride species generation. The authors conclude that the technique offers an easy and sensitive way to determine trace amounts of arsenic in human urine; the method also provides a convenient means to differentiate between toxic hydride forming arsenicals which might be present in environmental and/or biological samples and other essentially nontoxic organoarsenic compounds.",
Arsenic,1070455,"Bioindication of volatile elements emission by the Puyehue-Cordón Caulle (North Patagonia) volcanic event in 2011 Abstract: The emission of volatile pollutants from the volcanic eruption of the Puyehue-Cordón Caulle complex (North Patagonia Andean Range) that started in June 4th, 2011, was investigated by bioindication means with the epyphytic fruticose lichen Usnea sp. The elemental composition of pooled samples made up with 10 lichen thalli were analysed by Instrumental Neutron Activation Analysis. Eleven sampling sites were selected within the impacted region at different distance from the volcanic source. Five sites were selected as they were already sampled in a previous study prior to the eruption. Two other new sampling sites were selected from outside the impacted zone to provide non-impacted baseline sites. The elements associated with the lichen incorporation of particulate matter (PM) of geological origin were identified by linear correlation with a geochemical tracer (Sm concentrations). The elements associated with PM uptake were Ce, Eu, Fe, Hf, La, Lu, Na, Nd, Sb, Sc, Se, Ta, Tb, Th, U, and Yb. Arsenic and Cs concentrations showed contributions exceeding the PM fraction in sites near the volcanic centre, also higher than the baseline concentrations, which could be associated with permanent emissions from the geothermal system of the Puyehue-Cordón Caulle complex. The lichen concentrations of Ba, Ca, Co, Hg, K, Rb, Sr, and Zn were not associated with the PM, not showing higher concentrations in the sites nearby the volcanic source or respect to the baseline values either. Therefore, there is no indication of the emission of volatile forms of these elements in the lichen records. The lichen records only identified Br volatile emissions associated with the Puyehue-Cordón Caulle complex eruption in 2011.",
Arsenic,1597349,"A prospective study of arsenic exposure, arsenic methylation capacity, and risk of cardiovascular disease in Bangladesh Abstract: BACKGROUND: Prospective studies that evaluate the influence of arsenic methylation capacity on cardiovascular disease (CVD) risk are lacking. OBJECTIVE: To evaluate the association of arsenic exposure from drinking water and arsenic methylation capacity with CVD risk. METHOD: We conducted a case-cohort study of 369 incident fatal and non-fatal cases of CVD, including 148 stroke cases and 211 cases of heart disease, and a subcohort of 1,109 subjects randomly selected from the 11,224 participants in the Health Effects of Arsenic Longitudinal Study. RESULTS: The adjusted hazard ratio (HR) for all CVD, heart disease, and stroke in association with a standard deviation increase in baseline well arsenic (112 µg/L) was 1.15 (95% CI: 1.01, 1.30), 1.20 (95% CI: 1.04, 1.38), and 1.08 (95% CI: 0.90, 1.30), respectively. Adjusted HRs for the second and third tertiles of urinary monomethylarsonic acid (MMA)% relative to the lowest tertile, respectively, were 1.27 (95% CI: 0.85, 1.90) and 1.55 (95% CI: 1.08, 2.23) for all CVD, and 1.65 (95% CI: 1.05, 2.60) and 1.61 (95% CI: 1.04, 2.49) for heart disease specifically. The highest versus lowest ratio of urinary dimethylarsinic acid (DMA) to MMA was associated with a significantly decreased risk of CVD (HR=0.54; 95% CI: 0.34, 0.85) and heart disease (HR=0.54; 95% CI: 0.33, 0.88). There was no apparent association between arsenic metabolite indices and stroke risk. The joint effects of incomplete arsenic methylation capacity, indicated by higher urinary MMA% or lower urinary DMA%, with higher levels of well arsenic on heart disease risk were additive. There was some evidence of a synergy of incomplete methylation capacity with older age and cigarette smoking. CONCLUSIONS: Arsenic exposure from drinking water and incomplete methylation capacity of arsenic were adversely associated with heart disease risk.",
Arsenic,1350768,ATOMIC-ABSORPTION SPECTROPHOTOMETRIC DETERMINATION OF ARSENIC AND SELENIUM IN PREMIXED INERT GAS (ENTRAINED AIR) HYDROGEN FLAMES WITH A MULTI-FLAME BURNER Abstract: ,
Arsenic,1377951,"Arsenite Induces S Phase Delay In U937 Cells Via Downregulation Of CDC25A Phosphatase Abstract: Arsenite is an effective chemotherapeutic agent in the treatment of certain cancers, but its mechanism of action is unknown. 5-Bromo-2?-deoxyuridine pulse chase experiments show that arsenite markedly increases S-phase transit time in U937 myeloid leukemia cells. Given the high percentage of S phase cells in a cancer cell population, it is likely that an effect of arsenite on S phase progression can contribute significantly to overall growth inhibition. The purpose of this study is to identify potential protein targets of arsenite that play a role in S phase delay. Cdc25A phosphatase controls S phase progression by dephosphorylating sites of inhibitory phosphorylation (T14 and Y15) on cyclin E-cdk2. Immunoblotting reveals that a 2 h treatment of U937 cells with 5 uM NaAsO2 results in a dramatic decrease in cdc25A protein levels. Co-immunoprecipitation experiments confirm that cyclin E-cdk2 is more phosphorylated at T14 and Y15 in the presence of arsenite. Kinase activity assays reveal an arsenite-dependent decrease in cyclin E-associated cdk2 activity. Therefore, depletion of cdc25A by arsenite may contribute to inhibition of S phase entry and progression. There exists an S phase checkpoint known to be mediated by phosphorylation and ubiquitin-dependent proteasomal degradation of cdc25A. However, a time course of concurrent treatment of cells with cycloheximide and arsenite reveals that cdc25A is not degraded more quickly upon arsenite treatment, so arsenite doesn?t deplete cdc25A levels via this well-characterized S phase checkpoint. We?ve found by real time RT-PCR that arsenite treatment does reduce the abundance of cdc25A mRNA within much the same time frame as that seen with cdc25A protein. Nuclear run-on and mRNA half-life assays and polyribosomal analysis will be used to assess the roles of transcriptional regulation, message destabilization and translational suppression in the mechanism of arsenite- induced cdc25A decline. Future studies will seek to identify a more proximal target of arsenite responsible for the observed effect on cdc25A levels and S phase transit.",
Arsenic,1393469,"Development and Application of a ""Real Time"" Lead-in-Air Analyzer in Controlling Lead Exposure at a Primary Lead Smelter Abstract: A ""real time"" lead (7439921) in air analyzer was developed to aid in preventing employees' excessive exposure to fugitive emissions in a primary lead smelter. An instrument was described in which dust is collected on paper tape filters, and lead analyzed by X-ray fluorescence. Accuracy was assessed; samples from 0 to 130 micrograms of lead on tape, as analyzed by atomic absorption, gave a standard deviation of 4.1 micrograms when compared to the result given by the instrument. Interelement interference could pose a problem in some applications, as the instrument has similar sensitivity to arsenic and very slight sensitivity to zinc. Five of these instruments are currently in use at Mount Isa Mines Limited. The only maintenance required is to clean the detector head once per month and recalibration once per year. Benefits for engineering control monitoring include ""real time"" warning that high pollutant levels are present, identification of troublesome areas in order to aid in the development of controls, historical record of abnormal hazardous material concentrations, assistance in monitoring performance of controls, and work practices. Monitoring results have changed attitudes toward the importance of adhering to proper work practices. Process malfunctions can be detected very early.",
Arsenic,1353765,"Arsenic methylation and bladder cancer risk in case-control studies from Argentina and the United States Abstract: Introduction: Several human studies have indicated that arsenic methylation could play an important role in arsenic-caused disease. Most of these studies have occurred in Taiwan and only one has involved bladder cancer. Methods: We examined the association between urinary arsenic methylation patterns and bladder cancer in two case-control studies, one in the western U.S. and one in Argentina. Both areas included populations ingesting arsenic-contaminated drinking water at concentrations near 100 ug/L. Results: The U.S. study included 23 cases and 49 controls, and the Argentina study included 114 cases and 114 controls. In both studies, cases and controls had similar proportions of inorganic arsenic (U.S.: 13.3 versus 12.3%, p0.49; Argentina: 14.9 versus 17.3%, p0.06), monomethylarsonate (MMA) (U.S.: 13.7 versus 12.3%, p0.31; Argentina: 14.9 versus 14.3%, p0.66), and dimethylarsinate (DMA) (U.S.: 73.0 versus 75.5%, p0.25; Argentina: 70.2 versus 68.4%, p0.39). However, in the U.S. study subjects with higher arsenic exposures (median water concentration of 100  g/L), risks were elevated for those in the upper tertile of percent MMA compared to those in the Abstracts Epidemiology • Volume 15, Number 4, July 2004 S80 © 2004 Lippincott Williams & Wilkins lower tertiles of percent MMA (OR, 8.76; 95% CI, 1.06-72.2). And, in the Argentina subjects with a five year average maximum exposure of 50 to 200 ug/L, bladder cancer risks were elevated in subjects in the upper tertile of percent MMA compared to those in the lower tertiles, although this effect was only seen in smokers (OR, 6.71; 95% CI, 1.33-34.0). Similar effects for percent MMA were not seen in smokers exposed to drinking water arsenic above 200 ug/L, although the confidence intervals were wide (OR, 1.25; 95% CI, 0.18-8.44). Discussion: Overall, the findings of these two studies suggest that people with a lower capacity to methylate MMA to DMA are more susceptible to arsenic-caused bladder cancer and this effect can occur at concentrations of arsenic in drinking water near 100 ug/L.",
Arsenic,1579361,"Evaluation of heavy metals (As and Cd) contamination in the edible fish along Karachi-Makran coast Abstract: The aim of this paper is to measure the concentration levels of As and Cd in edible fish from the area of Karachi – Makaran coast, Pakistan. These two metals are very toxic with serious health effects. These metals are released directly through the industrial sewage into Malir River and transferred to fish and then to human beings. It was observed that the high concentration of As in fish flesh samples were most probably due to the presence of significant amount of As in the industrial effluents discharged into the Indus river. The fish of sporadic occurrence also exhibits variable Cd concentrations in the flesh, which do not meet the standards of World Health Organizations.",
Arsenic,1342861,"INDUCTION OF HEME OXYGENASE - A GENERAL RESPONSE TO OXIDANT STRESS IN CULTURED-MAMMALIAN-CELLS Abstract: Accumulation of heme oxygenase mRNA is strongly stimulated by treatment of cultured human skin fibroblasts with ultraviolet radiation, hydrogen peroxide, or the sulfhydryl reagent sodium arsenite (S. M. Keyse and R. M. Tyrrell. Proc. Natl. Acad. Sci. USA, 86: 99-103, 1989). Since this will result in a transient reduction in the prooxidant state of cells, the phenomenon may represent an important inducible antioxidant defense mechanism. To examine the generality of the response, we have measured the accumulation of the specific mRNA in a variety of human and mammalian cell types after inducing treatments. Induction by sodium arsenite is observed in all additional human cell types tested. This includes primary epidermal keratinocytes and lung and colon fibroblasts as well as established cell lines such as HeLa, TK6 lymphoblastoid, and transformed fetal keratinocytes. Strong induction of heme oxygenase mRNA is also observed following sodium arsenite treatment of cell lines of rat, hamster, mouse, monkey, and marsupial origin. The agents which lead to induction in cultured human skin fibroblasts fall into two categories: (a) those which are oxidants or can generate active intermediates (ultraviolet A radiation, hydrogen peroxide, menadione, and the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate); (b) agents which are known to interact with or modify cellular glutathione levels (buthionine sulfoximine, sodium arsenite, iodoacetamide, diamide, and cadmium chloride). These observations strongly support the hypothesis that induction of the enzyme is a general response to oxidant stress in mammalian cells and are consistent with the possibility that the cellular redox state plays a key role.",
Arsenic,1016517,"Comparison of drinking water, raw rice and cooking of rice as arsenic exposure routes in three contrasting areas of West Bengal, India Abstract: Remediation aimed at reducing human exposure to groundwater arsenic in West Bengal, one of the regions most impacted by this environmental hazard, are currently largely focussed on reducing arsenic in drinking water. Rice and cooking of rice, however, have also been identified as important or potentially important exposure routes. Quantifying the relative importance of these exposure routes is critically required to inform the prioritisation and selection of remediation strategies. The aim of our study, therefore, was to determine the relative contributions of drinking water, rice and cooking of rice to human exposure in three contrasting areas of West Bengal with different overall levels of exposure to arsenic, viz. high (Bhawangola-I Block, Murshidibad District), moderate (Chakdha Block, Nadia District) and low (Khejuri-I Block, Midnapur District). Arsenic exposure from water was highly variable, median exposures being 0.02 ?g/kg/d (Midnapur), 0.77 ?g/kg/d (Nadia) and 2.03 ?g/kg/d (Murshidabad). In contrast arsenic exposure from cooked rice was relatively uniform, with median exposures being 0.30 ?g/kg/d (Midnapur), 0.50 ?g/kg/d (Nadia) and 0.84 ?g/kg/d (Murshidabad). Cooking rice typically resulted in arsenic exposures of lower magnitude, indeed in Midnapur, median exposure from cooking was slightly negative. Water was the dominant route of exposure in Murshidabad, both water and rice were major exposure routes in Nadia, whereas rice was the dominant exposure route in Midnapur. Notwithstanding the differences in balance of exposure routes, median excess lifetime cancer risk for all the blocks were found to exceed the USEPA regulatory threshold target cancer risk level of 10(-4)-10(-6). The difference in balance of exposure routes indicate a difference in balance of remediation approaches in the three districts.",
Arsenic,1326974,"Coordinated regulation of angiopoietin-1 and vascular endothelial growth factor by arsenite in human brain microvascular pericytes: implications of arsenite-induced vascular dysfunction Abstract: Arsenite is an environmental toxicant that is associated with vascular disease; however, the underlying mechanism of its toxicity has yet to be elucidated. Vascular stability appears to be tightly regulated by several vasoactive proteins produced by two adjacent vascular cells, endothelial cells (EC) and pericytes. The disruption of vascular stability may be involved in arsenite toxicity. The roles of angipoietins (Ang) and vascular endothelial growth factor (VEGF) in this process have been evaluated, but these studies have mostly been limited to EC. In this study, we used human brain microvascular pericytes (HBMP) to evaluate the effects of arsenite on Ang-1 and VEGF regulation. Ang-2 was reported to be not detected in HBMP. Arsenite decreased Ang-1 secretion in a time and dose-dependent manner, while it increased VEGF secretion. Although arsenite did not alter Ang-1 mRNA expression, it increased intracellular Ang-1 protein levels in a dose-dependent manner, suggesting a role for arsenite in the intracellular trapping of Ang-1. Contrary to Ang-1, the expression of VEGF mRNA was dose-dependently up-regulated by arsenite. Treatment with N-actyl-l:-cysteine (NAC) alone decreased the release of Ang-1, but failed to attenuate the arsenite-induced decrease in Ang-1 secretion, while NAC completely blocked the arsenite-stimulated VEGF secretion. These results indicate that reactive oxygen species are involved in the regulation of VEGF, but not of Ang-1, secretion in response to arsenite treatment in pericytes. Furthermore, immunocytochemical analysis using confocal microscopy revealed a colocalization of Ang-1 with actin filaments that occurred independently of tubulin. In conclusion, arsenite decreases Ang-1 secretion and increases VEGF secretion, which may offer new insight into understanding the arsenite toxicity associated with vascular instability and subsequent development of vascular disease.",
Arsenic,1256745,"Surface alteration of realgar (As4S4) by Acidithiobacillus ferrooxidans Abstract: The chemical and physical characteristics of realgar (an arsenic sulfide mineral that occurs in several crystalline forms) in the presence of Acidithiobacillus ferrooxidans BY-3 were investigated in this work. Grains of the mineral were incubated for 10, 20, and 30 days with A. ferrooxidans cultured in 9K medium at 30 °C and at 150 rpm agitation. Abiotic control experiments were conducted in identical solutions. The effect of bioleaching on the surface properties of realgar was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), inductively coupled plasma atomic emission spectroscope (ICP-AES), X-ray diffraction (XRD), and Raman spectroscopy. SEM and EDS analyses confirmed the ability of A. ferrooxidans to modify surfaces of realgar and to efficiently enhance its dissolution. ICP-AES showed the dissolution and precipitation of realgar during bioleaching. Based on the XRD pattern and the Raman spectra, the decrease in arsenic in the liquid phase was due to co-precipitation of the mineral with Fe(III) or Fe(III) compounds (e.g., jarosite or goethite). Thus, not only did Fe(III) alter the surface of realgar, but it also promoted its dissolution during bioleaching.",
Arsenic,1025943,"N-acetylcysteine attenuates arsenite-induced oxidative injury in dorsal root ganglion explants Abstract: Chronic exposure to arsenic causes health problems, including peripheral neuropathy. Oxidative stress is one of the mechanisms underlying arsenic-induced neurotoxicity. For this report, we studied the protective effect of N-acetylcysteine (NAC) on arsenic-induced oxidative injury in dorsal root ganglion (DRG) explants. After 24-h incubation, NAC concentration-dependently attenuated arsenite-induced depletion in glutathione (GSH) content and increases in the ratio of oxidized GSH/reduced GSH (GSSG/GSH ratio) in DRG explants. Furthermore, NAC inhibited arsenite-induced elevation in the expression of stress proteins, such as heat shock protein 70 and heme oxygenase 1, as well as arsenite-induced phosphorylation of p38 mitogen-activated protein kinase. Incubation with NAC ameliorated arsenite-induced apoptosis by abolishing both mitochondrial and endoplasmic reticulum (ER) pathways. In the mitochondrial pathway, NAC attenuated arsenite-induced elevation in Bcl-2 level and cytosolic cytochrome c, as well as arsenite-induced reduction in procaspase-3 levels. In the ER pathway, NAC suppressed arsenite-induced increases in activating transcription factor 6 and C/EBP homologous protein in the nuclear fraction. Furthermore, arsenite-induced reductions in procaspase-12 and elevation in BIP and caspase-12, an ER-specific enzyme, were prevented after NAC incubation. Taken together, our results demonstrate that NAC is neuroprotective against arsenite-induced oxidative injury in DRG explants. Furthermore, NAC inhibits arsenite-induced toxicity by inhibiting ER and mitochondrion activation. Our data indicate that NAC is potentially therapeutic for arsenite-induced peripheral neuropathy.",
Arsenic,2345824,"Mercury, autoimmunity, and environmental factors on cheyenne river sioux tribal lands Abstract: Mercury (Hg), shown to induce autoimmune disease in rodents, is a ubiquitous toxicant throughout Cheyenne River Sioux Tribe (CRST) lands. CRST members may be exposed to Hg through fish consumption (FC), an important component of native culture that may supplement household subsistence. Our goals were to ascertain whether total blood Hg levels (THg) reflect Hg exposure through FC and smoking, and determine whether THg is associated with the presence of anti-nuclear antibody (ANA) and specific autoantibodies (sAuAb). We recruited 75 participants who regularly consume fish from CRST waters. Hg exposure through FC and smoking were assessed via questionnaires. Whole blood samples were collected from participants, and THg was measured using ICP-MS. ANA and sAuAb in serum were modeled using demographic and exposure information as predictors. Female gender, age, and FC were significant predictors of THg and sAuAb; self-reported smoking was not. 31% of participants tested positive for ANA ? 2+. Although ANA was not significantly associated with Hg, the interactions of gender with Hg and proximity to arsenic deposits were statistically significant (P &lt; 0.05). FC resulted in a detectable body burden of Hg, but THg alone did not correlate with the presence of ANA or sAuAb in this population.",
Arsenic,1936127,"Migration of Cu, Zn, Cd and As in epikarst water affected by acid mine drainage at a coalfield basin, Xingren, Southwest China Abstract: ",
Arsenic,1255504,"Adsorption behavior of arsenic relating to different natural solids: Soils, stream sediments and peats Abstract: The sorption of anthropogenically derived arsenic to natural solids plays an important role in the mobility and fate of this toxic metalloid in the environment. The adsorption affinity of dissolved As(V) and As(III) to contrasting natural solids was investigated using model solutions of As(V)/As(III) and homogenized samples of soils, stream sediments and peat cores. The adsorption of As(III) and As(V) on investigated sorbents ran mostly according to the Langmuir model, with high correlation factors (&gt;0.7). Sorption capacities varied from 3.5×10(-3) to 2.0×10(-1)mmol/g of As, whereas As(III) achieved a higher adsorption affinity due to the presence of Fe ions in the model solution. The lower horizons of soils and the intact peat, characterized by high enrichment factors of As content (R&gt;1), represented a more stable system with decreased adsorption/desorption dynamics of As transport. A higher surface activity of solids associated with R&lt;1, and an increased As mobility in the solid-water interface, prevailed in upper horizons of the soil and intact peat, where the contact with atmospheric deposition was expected. Stream sediments proved to be a well-balanced system with R?1. A strong As-Fe correlation in the natural solids confirmed As affinity to Fe particles.",
Arsenic,627186,"Lipid oxidative damage and distribution of inorganic arsenic and its metabolites in the rat nervous system after arsenite exposure: Influence of alpha tocopherol supplementation Abstract: Inorganic arsenic (iAs) exposure causes peripheral neuropathy. Oxidative effects caused by iAs exposure in peripheral nerves have been incompletely characterized. This study analyzed arsenic and lipid oxidative damage in the brain, spinal cord, and sciatic and sensory sural nerves following arsenite exposure. This study also explored whether alpha tocopherol (alpha-TOC) administration mitigates arsenite-induced oxidative damage. Thiobarbituric acid-reactive substance (TBARS) levels and distributions of iAs and its metabolites were evaluated in male Wistar rats following 30d of sodium arsenite exposure (10mg/kg bodyweight (bw)/d, by gavage). A second group also received alpha-TOC (125mg/kg bw/d, by gavage) during the final 20d of arsenite administration. Arsenite exposure caused increased TBARS levels within each region of the nervous system; oxidative stress was most pronounced in the sural and sciatic nerves. In addition there was a positive quadratic relationship between TBARS levels and the concentration of arsenicals found in the nervous system (r(2)=0.878, p<0.001). Dimethylarsenic was the predominant metabolite of iAs found. Animals alpha-TOC-treated had a 1.7-5.2-fold reduction in TBARS levels when compared with rats that received iAs alone. These results suggest that oxidative damage may be the main mechanism of toxicity induced by exposure of the peripheral nervous system to arsenite and that such damage could be attenuated by alpha-TOC-supplementation.",
Arsenic,1025812,"All-E lutein and 3'-epilutein in the epidermis of chronic arsenic poisoning Abstract: Identification and quantification of carotenoids in the epidermis of nine patients of chronic arsenic poisoning were done using isocratic reverse phase high performance liquid chromatography (HPLC). The major carotenoids in all the skin biopsies were all-E lutein and 3'-epilutein. Small amount of 2',3'-anhydrolutein, all-E zeaxanthin, and 13-Z zeaxanthin were also present in some of the biopsy samples. Alpha-carotene, beta-carotene, and lycopene were not detected in any sample. The mean (+/- SD) concentration of all-E lutein in the epidermis of healthy volunteers was 1.09 +/- 0.26 microgram/g of wet tissue, whereas it was only 0.29 +/- 0.10 microgram/g in the diffuse dark brown spots of chronic arsenic poisoning. In raindrop-shaped discoloration spots of skin the mean concentration of all-E lutein was 0.86 +/- 0.29 microgram/g of wet tissue. The difference between the concentrations of all-E lutein in the epidermis of healthy volunteers versus patients was for the diffuse dark brown spots statistically significantly (p &lt; 0.05) lower, while this was not significant for the raindrop-shaped discoloration spots. This study suggests that arsenic exposure reduces the number, as well as concentrations of, carotenoids in skin.",
Arsenic,1032892,"Arsenical cancer of skin. Histologic study with special reference to Bowen's disease Abstract: A total of 238 arsenical skin cancers in 153 patients (98 men and 55 women) were histologically studied; 117 patients (76.47%) were older than 50. Of the 238 lesions, 46 were epidermoid carcinoma, 36 basal cell (23 deep and 13 superficial), 139 intraepidermal (18 type B keratoses and 121 classical Bowen's lesions and variants) and 17 combined forms. Clinically, it was often impossible to differentiate superficial basal cell carcinoma, intraepidermal carcinoma and combined forms. Bowen's variants (10 with squamous eddies, 6 with features of seborrheic keratosis and 5 with horn formation) were described and illustrated. The combined forms were mixtures of superficial basal cell carcinoma, Bowen's lesion or its variants and Jadassohn epithelioma, Among the 36 basal cell carcinomas, ten revealed bizarre multinucleated giant cells and nuclear atypicalities, three in deep and seven in superficial. Arsenical keratoses consisted of benign type A and malignant type B (intraepidermal carcinoma). Among the 81 type A keratoses 57 revealed no cell atypicalities and 24 only mild ones. Relationships of Bowen's lesions to keratoses and to invasive and metastasizing carcinomas and of keratoses type A to type B and to epidermoid carcinomas were discussed.",
Arsenic,60254,"On the relations between atmospheric pollution in urban and rural localities and mortality from cancer, bronchitis and pneumonia, with particular reference to 3:4 benzopyrene, beryllium, molybdenum, vanadium and arsenic Abstract: The association between smoke and mortality from lung cancer and respiratory diseases was investigated. Special consideration was given to polycyclic hydrocarbons and trace elements found in atmospheric pollution. A total of 41 locations in England were involved in the study. Records of cause of death were surveyed through death certificates from the various locations. The amount of smoke per cubic meter of air was estimated from a direct photometric measure of the blackness of the filter paper through which a measured volume of air was drawn. The air was also analyzed for 3,4-benzopyrene (50328) (BP), 1,12-benzoperylene (191242), pyrene (129000), and fluoranthene (206440). The trace elements beryllium (7440417) (Be), molybdenum (7439987) (Mo), arsenic (7440382) (As), vanadium (7440622), and zinc (7440666) (Zn) were analyzed spectrophotographically. The occurrence of lung cancer, bronchitis and pneumonia showed a strong correlation with the amount of smoke. For example, in one area where the smoke density was 15 milligrams per 1000 cubic meters (mg/1000m3) the standard mortality ratio (SMR) for those disease was 454; and in another area where the smoke density was 562mg/1000m3, the SMR was 1994. For lung cancer and bronchitis, BP emerged clearly as the predominant polycyclic hydrocarbon and Be and Mo were the elements of most consequence. The elements As, Zn and vanadium also showed an association, although somewhat weaker. For bronchitis, Mo was the most important element; and for pneumonia, Be and vanadium showed appreciable correlation to the mortality rates. The author concludes that there is a relationship between atmospheric pollution and mortality rates from respiratory diseases.",
Arsenic,627451,"Genomic and proteomic profiling of responses to toxic metals in human lung cells Abstract: Examining global effects of toxic metals on gene expression can be useful for elucidating patterns of biological response, discovering underlying mechanisms of toxicity, and identifying candidate metal-specific genetic markers of exposure and response. Using a 1,200 gene nylon array, we examined changes in gene expression following low-dose, acute exposures of cadmium, chromium, arsenic, nickel, or mitomycin C (MMC) in BEAS-2B human bronchial epithelial cells. Total RNA was isolated from cells exposed to 3 M Cd(II) (as cadmium chloride), 10 M Cr(VI) (as sodium dichromate), 3 g/cm2 Ni(II) (as nickel subsulfide), 5 M or 50 M As(III) (as sodium arsenite), or 1 M MMC for 4 hr. Expression changes were verified at the protein level for several genes. Only a small subset of genes was differentially expressed in response to each agent: Cd, Cr, Ni, As (5 M), As (50 M), and MMC each differentially altered the expression of 25, 44, 31, 110, 65, and 16 individual genes, respectively. Few genes were commonly expressed among the various treatments. Only one gene was altered in response to all four metals (hsp90), and no gene overlapped among all five treatments. We also compared low-dose (5 M, noncytotoxic) and high-dose (50 M, cytotoxic) arsenic treatments, which surprisingly, affected expression of almost completely nonoverlapping subsets of genes, suggesting a threshold switch from a survival-based biological response at low doses to a death response at high doses.",
Arsenic,1021790,"Unfolded protein response signaling and MAP kinase pathways underlie pathogenesis of arsenic-induced cutaneous inflammation Abstract: Arsenic exposure through drinking water is a major global public health problem and is associated with an enhanced risk of various cancers including skin cancer. In human skin, arsenic induces precancerous melanosis and keratosis, which may progress to basal cell and squamous cell carcinoma. However, the mechanism by which these pathophysiologic alterations occur remains elusive. In this study, we showed that subchronic arsenic exposure to SKH-1 mice induced unfolded protein response (UPR) signaling regulated by proteins, inositol-requiring enzyme-1 (IRE1), PKR-like endoplasmic reticulum kinase (PERK) and activating transcription factor 6 (ATF6). Arsenic activated all three UPR regulatory proteins in the skin. Arsenic induced IRE1 phosphorylation which resulted in augmented splicing of X-box binding protein 1 (XBP-1) leading to its migration to the nucleus, and also enhanced transcriptional activation of downstream target proteins. Hyperphosphorylation of PERK which induces eukaryotic translation initial factor 2? (eIF2?) in a phosphorylation-dependent manner enhanced translation of ATF4, in addition to augmenting proteolytic activation of ATF6 in arsenic-treated skin. A similar increase in the expression of CHOP was observed. Enhanced XBP-1s, ATF4, and ATF6 regulated downstream chaperones GRP94 and GRP78. In addition, arsenic induced inflammation-related p38/MAPKAPK-2 MAPK signaling and alterations in Th-1/Th-2/Th-17 cytokines/chemokines and their receptors. Antioxidant N-acetyl cysteine blocked arsenic-induced reactive oxygen species, with a concomitant attenuation of UPR and mitogen-activated protein kinase (MAPK) signaling and proinflammatory cytokine/chemokine signatures. Our results identify novel pathways involved in the pathogenesis of arsenic-mediated cutaneous inflammation which may also be related to enhanced cancer risk in arsenic exposed cohorts.",
Arsenic,84901,"Inorganic arsenic compounds: are they carcinogenic, mutagenic, teratogenic? Abstract: This review examines and evaluates the literature on the ability of inorganic arsenic compounds to cause cancer in humans and laboratory animals. The epidemiological data that supports the position that inorganic arsenical derivatives are carcinogenic in humans is convincing and difficult to deny because of their consistency. These data are from studies of different occupational exposures such as smelter and pesticide workers, as well as from studies of drinking water, wines and medicinal tonics that contained or were contaminated with inorganic compounds of arsenic. Indeed, positive dose-response relationships between cancer incidence or mortality with many inorganic arsenical substances have been shown. Despite the presence of data which confuse the interpretation and evaluation of epidemiological data, associated neoplasms of the lungs, skin and gastrointestinal systems have been observed as a result of exposure to inorganic arsenic compounds. The mechanism of carcinogenicity of inorganic arsenical substances in humans is unknown. Inorganic arsenic compounds are not carcinogenic in laboratory animals by most routes of administration. However, further studies (subchronic, chronic, carcinogenic) using intratracheal and other conventional routes in other animal species would appear to be warranted. More so, especially since there is no evidence that organic arsenic compounds are carcinogenic in numerous mammalian species. Inorganic derivatives of arsenic are not mutagenic but may be teratogenic. This latter conclusion is dependent on the method of administration and size of the dose, as well as on the species of animal used for the study.",
Arsenic,2347639,"Novel interface for on-line coupling of capillary electrophoresis with inductively coupled plasma mass spectrometry and its application in simultaneous speciation analysis of arsenic and selenium Abstract: A simple and highly efficient on-line system coupling of capillary electrophoresis to inductively coupled plasma mass spectrometer (CE-ICP-MS) for simultaneous separation and determination of arsenic and selenium compounds was developed. CE was coupled to an ICP-MS by a sprayer with a novel direct injection high efficiency nebulizer (DIHEN) chamber as the interface. By using this interface, six arsenic species, including arsenite (As(III), arsenate (As(V)), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) and five selenium species, such as sodium selenite (Se(IV)), sodium selenate (Se(VI)), selenocysteine (SeCys), selenomethionine (SeMet), and se-methylselenocysteine (MeSeCys) were baseline separated and determined in a single run within 9 min under the optimized conditions. Minimum dead volume, low and steady sheath flow liquid, high nebulization efficiency and high sample transport efficiency were obtained by using this interface. Detection limits were in the range of 0.11 - 0.37 ?g L-1 for the six arsenic compounds (determined as 75As at m/z 75) and 1.33 - 2.31 ?g L-1 for the five selenium species (determined as 82Se at m/z 82). Repeatability expressed as the relative standard deviations (RSD, n = 6) of both migration time and peak area were better than 2.68% for arsenic compounds and 3.28% for selenium compounds, respectively. The proposed method had been successfully applied for the determination of arsenic and selenium species in the certified reference materials DORM-3, water, urine and fish samples.",
Arsenic,1027649,"Internal exposure of waste incineration workers to organic and inorganic substances Abstract: One hundred and twenty-two persons employed in an industrial waste incineration plant were examined with respect to organic and inorganic substances which may be produced during the combustion of different waste. The employees were divided into three groups: persons with contact with the incinerator (WI workers, n = 45), periphery workers (n = 54) and management (n = 23). For the evaluation of internal exposure, the levels of lead, cadmium, mercury, benzene, toluene, ethylbenzene and m-xylene in blood, chromium in the erythrocytes, polychlorinated biphenyls, hexachlorobenzene and pentachlorophenol in plasma, and arsenic, chromium, nickel, vanadium, chlorophenols and hydroxypyrene in urine were determined. The internal exposures of the three groups were tested against each other and were compared with the reference values of the general population. Differences between the groups investigated were tested using the U test according to Wilcoxon, Mann and Whitney (P &lt; 0.05). The biological exposure limits valid in Germany (BAT values) were not exceeded in any cases. Compared with the background levels of the German population, certain parameters were exceeded in several employees. Significantly higher levels of the WI workers in comparison to both periphery workers and management were found for toluene in blood (median: 1.1 vs 0.9 vs 0.6 microgram/l). For the lead and cadmium levels in blood and for the urinary excretion of arsenic, 2,4-dichlorophenol and tetrachlorophenols, statistical differences were found only between WI workers and one of the other groups. However, in all cases the elevations were very small and of interest more from the environmental than from the occupational point of view. It must be stressed that this waste incineration plant is very modern in terms of worker health and safety. At older plants without corresponding health and safety measures, higher internal exposure of the employees to hazardous substances may exist.",
Arsenic,1359581,"New solvent for silver diethyldithiocarbamate in determination of arsenic Abstract: HEEP COPYRIGHT: BIOL ABS. The monoethanolamine-chloroform system is suggested as a new solvent for silver diethyldithiocarbamate in As (a toxic element) determination. This solvent is as sensitive, accurate and precise as normally used pyridine and is less expensive and without any pungent odor.",
Arsenic,1332037,"Regulation of apoptosis in human melanoma and neuroblastoma cells by statins, sodium arsenite and TRAIL: a role of combined treatment versus monotherapy Abstract: Treatment of melanoma cells by sodium arsenite or statins (simvastatin and lovastatin) dramatically modified activities of the main cell signaling pathways resulting in the induction of heme oxygenase-1 (HO-1) and in a downregulation of cyclooxygenase-2 (COX-2) protein levels. Through heme degradation and the production of carbon monoxide and biliverdin, HO-1 plays a protective role in different scenario of oxidative stress followed by mitochondrial apoptosis. Both sodium arsenite and statins could be efficient inducers of apoptosis in some melanoma cell lines, but often exhibited only modest proapoptotic activity in others, due to numerous protective mechanisms. We demonstrated in the present study that treatment by sodium arsenite or statins with an additional inhibition of HO-1 expression (or activation) caused a substantial upregulation of apoptosis in melanoma cells. Sodium arsenite- or statin-induced apoptosis was independent of BRAF status (wild type versus V600E) in melanoma lines. Monotreatment required high doses of statins (20-40 ?M) for effective induction of apoptosis. As an alternative approach, pretreatment of melanoma cells with statin at decreased doses (5-20 ?M) dramatically enhanced TRAIL-induced apoptosis, due to suppression of the NF-?B and STAT3-transcriptional targets (including COX-2) and downregulation of cFLIP-L (a caspase-8 inhibitor) protein levels. Furthermore, combined treatment with sodium arsenite and TRAIL or simvastatin and TRAIL efficiently induced apoptotic commitment in human neuroblastoma cells. In summary, our findings on enhancing effects of combined treatment of cancer cells using statin and TRAIL provide the rationale for further preclinical evaluation.",
Arsenic,2337063,"Phytochelatin-metal(loid) transport into vacuoles shows different substrate preferences in barley and Arabidopsis Abstract: Cadmium (Cd) and arsenic (As) are toxic to all living organisms, including plants and humans. In plants, Cd and As are detoxified by phytochelatins (PCs) and metal(loid)-chelating peptides and by sequestering PC-metal(loid) complexes in vacuoles. Consistent differences have been observed between As and Cd detoxification. Whereas chelation of Cd by PCs is largely sufficient to detoxify Cd, As-PC complexes must be sequestered into vacuoles to be fully detoxified. It is not clear whether this difference in detoxification pathways is ubiquitous among plants or varies across species. Here, we have conducted a PC transport study using vacuoles isolated from Arabidopsis and barley. Arabidopsis vacuoles accumulated low levels of PC2 -Cd, and vesicles from yeast cells expressing either AtABCC1 or AtABCC2 exhibited negligible PC2 -Cd transport activity compared with PC2 -As. In contrast, barley vacuoles readily accumulated comparable levels of PC2 -Cd and PC2 -As. PC transport in barley vacuoles was inhibited by vanadate, but not by ammonium, suggesting the involvement of ABC-type transporters. Interestingly, barley vacuoles exhibited enhanced PC2 transport activity when essential metal ions, such as Zn(II), Cu(II) and Mn(II), were added to the transport assay, suggesting that PCs might contribute to the homeostasis of essential metals and detoxification of non-essential toxic metal(loid)s.",
Arsenic,1021253,"Comparative effects of some local food condiments on sodium arsenite-induced clastogenicity Abstract: The modulatory effects of the aqueous extracts of some locally consumed food condiments namely garlic (Allium sativum), ginger (Zingiber officinale), sconio (Pimpinella anisumm LINNE) and cloves (Syzygium aromaticum) on the clastogenic effects of sodium arsenite, a known inorganic clastogen were assessed in mouse bone marrow cells using the micronucleus assay method. Results of preliminary investigation of the clastogenicity of the condiments show that aqueous extracts of these condiments have very mild clastogenic activity in mice in the order garlic &gt; ginger and sconio &gt; cloves and that extracts of ginger and sconio seem to have the same degree of clastogenicity. Pre-treatment of mice for seven days with extracts of the condiments orally before exposure to the oral dose (2.5 mg/kg body wt.) of sodium arsenite resulted in a remarkable reduction of the magnitude of formation of micronuclei in polychromatic erythrocytes of the bone marrow. The degree of reduction of the clastogenic effect of arsenite was of the order ginger &gt; garlic &gt; cloves &gt; sconio. This reduction of arsenite induced clastogenicity by aqueous extracts of the condiments may be due in part to the antioxidant properties of their chemical constituents, thus suggesting that the condiments may be useful in the prevention of arsenite-induced toxicity in areas where arsenic is an environmental contaminant.",
Arsenic,1019714,"Chemical speciation of arsenic in serum of uraemic patients Abstract: Chemical speciation of arsenic was carried out in serum of a total of 51 uraemic patients: 19 non-dialysis (ND), 18 haemodialysis (HD) and 14 continuous ambulatory peritoneal dialysis (CAPD) patients. The low molecular mass As species were separated by ion-exchange liquid chromatography and measured on-line by hydride generation atomic absorption spectrometry (HGAAS). The high molecular mass As species were separated by fast protein liquid chromatography, either size-exclusion, ion-exchange or affinity chromatography, and the fractions were digested and measured off-line with HGAAS. The mean total As concentrations in the serum of the three groups of the uraemic patients were significantly higher than the reference value (6.47 +/- 4.28, 5.12 +/- 5.58 and 4.67 +/- 5.41 micrograms l-1 for HD, ND and CAPD patients, respectively, versus the reference value of 0.96 +/- 1.52 micrograms l-1. The major As species in serum of the patients were dimethylarsinic acid (DMA) and arsenobetaine. The HD patients showed a significantly higher mean DMA level than ND and CAPD patients. No selective removal of different As species in serum of HD patients was observed after 4 h of haemodialysis. The inorganic As species in serum were bound to proteins, mainly transferrin (about 5-6% of total As in serum). This binding may play an important role in arsenic detoxification.",
Arsenic,1508605,"Electrochemical detection of arsenic(III) completely free from noble metal: Fe(3)O(4) microspheres-room temperature ionic liquid composite showing better performance than gold Abstract: In recent decades, electrochemical detection of arsenic(III) has been undergoing revolutionary developments with higher sensitivity and lower detection limit. Despite great success, electrochemical detection of As(III) still depends heavily on noble metals (predominantly Au) in a strong acid condition, thus increasing the cost and hampering the widespread application. Here, we report a disposable platform completely free from noble metals for electrochemical detection of As(III) in drinking water under nearly neutral condition by square wave anodic stripping voltammetry. By combining the high adsorptivity of Fe(3)O(4) microspheres toward As(III) and the advantages of room temperature ionic liquid (RTIL), the Fe(3)O(4)-RTIL composite modified screen-printed carbon electrode (SPCE) showed even better electrochemical performance than commonly used noble metals. Several ionic liquids with different viscosities and surface tensions were found to have a different effect on the voltammetric behavior toward As(III). Under the optimized conditions, the Fe(3)O(4)-RTIL composites offered direct detection of As(III) within the desirable range (10 ppb) in drinking water as specified by the World Health Organization (WHO), with a detection limit (3? method) of 8 × 10(-4) ppb. The obtained sensitivity was 4.91 ?A ppb(-1), which is the highest as far as we know. In addition, a possible mechanism for As(III) preconcentration based on adsorption has been proposed and supported by designed experiments. Finally, this platform was successfully applied to analyzing a real sample collected from Inner Mongolia, China.",
Arsenic,628033,"Arsenic-induced skin lesions among Atacameño people in Northern Chile despite good nutrition and centuries of exposure Abstract: It has been suggested that the indigenous Atacameño people in Northern Chile might be protected from the health effects of arsenic in drinking water because of many centuries of exposure. Here we report on the first intensive investigation of arsenic-induced skin lesions in this population. We selected 11 families (44 participants) from the village of Chiu Chiu, which is supplied with water containing between 750 and 800 microg/L inorganic arsenic. For comparison, 8 families (31 participants) were also selected from a village where the water contains approximately 10 microg/L inorganic arsenic. After being transported to the nearest city for blind assessment, participants were examined by four physicians with experience in studying arsenic-induced lesions. Four of the six men from the exposed village, who had been drinking the contaminated water for more than 20 years, were diagnosed with skin lesions due to arsenic, but none of the women had definite lesions. A 13-year-old girl had definite skin pigmentation changes due to arsenic, and a 19-year-old boy had both pigmentation changes and keratoses on the palms of his hands and the soles of his feet. Family interviews identified a wide range of fruits and vegetables consumed daily by the affected participants, as well as the weekly intake of red meat and chicken. However, the prevalence of skin lesions among men and children in the small population studied was similar to that reported with corresponding arsenic drinking water concentrations in both Taiwan and West Bengal, India--populations in which extensive malnutrition has been thought to increase susceptibility.",
Arsenic,1342726,"SELECTIVE-INHIBITION OF VIRUS PROTEIN-SYNTHESIS BY PROSTAGLANDIN A(1) - A TRANSLATIONAL BLOCK ASSOCIATED WITH HSP70 SYNTHESIS Abstract: Cyclopentenone prostaglandins are potent inhibitors of virus replication. The antiviral activity has been associated with the induction of 70-kDa heat shock protein (HSP70) synthesis. In this report, we describe that in African green monkey kidney cells infected with Sendai virus (SV) and treated with prostaglandin A1 (PGA1), SV protein synthesis was selectively blocked as long as HSP70 was being synthesized by the host cell. The block appeared to be at the translational level, as indicated by the following (i) PGA1 had no effect on SV primary transcription, and a dramatic decrease in the abundance of SV mRNA occurred only at later stages of infection; and (ii) treatment with PGA1 started at 6 h postinfection, at which time SV mRNA had already accumulated in infected cells, did not suppress the levels of NP mRNA, but it reduced the amount of ribosome-bound NP mRNA and caused a dramatic decrease in the level of genomic RNA. The PGA1-induced block of SV protein synthesis appeared to be cell mediated, since it was prevented by actinomycin D, while PGA1 had no effect on SV mRNA translation in vitro. The possibility that HSP70 could be a mediator of the antiviral effect is suggested by the fact that treatment with other classical inducers of HSP70, including sodium arsenite, cadmium, and heat shock at 42 degrees C for 5 h, also selectively prevented SV protein synthesis as long as heat shock protein synthesis occurred. Moreover, SV protein synthesis was not inhibited by PGA1 in murine Friend erythroleukemic cells, which lack the ability to induce HSP70 expression in response to PGA1.",
Arsenic,1354975,"Effects of arsenic (As-III) on lipid peroxidation, glutathione content and antioxidant enzymes in growing pigs Abstract: ",
Arsenic,1251437,"Selective induction of apoptosis of NB4 cells from G2+M phase by sodium arsenite at lower doses Abstract: Apoptosis of NB4 cells induced by sodium arsenite and arsenate was studied using flow cytometry and DNA gel electrophoresis in order to investigate their effects on cell cycle and determine the relationship between apoptosis and cell cycle. In this study, we found that: 1) at low doses, sodium arsenite selectively induced apoptosis of NB4 cells in G2+M phase of cell cycle after its being arrested in G2 phase. With increment of the cells blocked in G2 phase, dUTP-specifically labeling cells in G2+M phase increased without concomitant increment of dUTP-labeling cells in other two phases of cell cycle; 2) at high doses, extensive apoptosis was induced in NB4 cells from all phases of cell cycle without cell cycle preference and cell cycle blockade; 3) sodium arsenite-induced apoptosis of NB4 cells occurred in the presence of bcl-2 expression as the unapoptotic cells; 4) sodium arsenite with As3+ induced apoptosis of NB4 cells more strongly than sodium arsenate with As5+ did although both of them affected NB4 cells in the same pattern. These results not only suggested that both arsenite and arsenate induced apoptosis of NB4 cells through 2 different mechanisms--at low doses, arsenical might directly induce apoptosis through regulation of cell cycle checkpoint, while at high doses they might directly induce it, but also indicated that bcl-2 might not play an important role in arsenite or arsenate-induced apoptosis of NB4 cells, whereas chemical valence of As in a compound might be related to efficiency in arsenical induction of apoptosis.",
Arsenic,710892,"Decreased nitric oxide markers and morphological changes in the brain of arsenic-exposed rats Abstract: Epidemiological studies demonstrate an association between chronic consumption of arsenic contaminated water and cognitive deficits, especially when the exposure takes place during childhood. This study documents structural changes and nitrergic deficits in the striatum of adult female Wistar rats exposed to arsenic in drinking water (3 ppm, approximately 0.4 mg/kg per day) from gestation, throughout lactation and development until the age of 4 months. Kainic acid injected animals (10mg/kg, i.p.) were also analyzed as positive controls of neural cell damage. Morphological characteristics of cells, fiber tracts and axons were analyzed by means of light microscopy as well as immunoreactivity to neuronal nitric oxide synthase (nNOS). As nitrergic markers, nitrite/nitrate concentrations, nNOS levels and expression of nNOS-mRNA were quantified in striatal tissue. Reactive oxygen species (ROS) and lipid peroxidation (LPx) were determined as oxidative stress markers. Arsenic exposure resulted in moderate to severe alterations of thickness, organization, surrounding space and shape of fiber tracts and axons, while cell bodies remained healthy. These anomalies were not accompanied by ROS and/or LPx increases. By contrast, except the expression of nNOS-mRNA, all nitrergic markers including striatal nNOS immunoreactivity presented a significant decrease. These results indicate that arsenic targets the central nitrergic system and disturbs brain structural organization at low exposure levels.",
Arsenic,2337244,"Dissemination of well water arsenic results to homeowners in Central Maine: Influences on mitigation behavior and continued risks for exposure Abstract: Private wells in the United States are unregulated for drinking water standards and are the homeowner's responsibility to test and treat. Testing for water quality parameters such as arsenic (As) is a crucial first step for homeowners to take protective actions. This study seeks to identify key behavioral factors influencing homeowners' decisions to take action after receiving well As test results. A January 2013 survey of central Maine households (n=386, 73% response) who were notified 3-7years earlier that their well water contained As above 10?g/L found that 43% of households report installing As treatment systems. Another 30% report taking other mitigation actions such as drinking bottled water because of the As, but the remaining 27% of households did not act. Well water As level appears to be a motivation for mitigation: 31% of households with well water level between 10 and 50?g/L did not act, compared to 11% of households with well water &gt;50?g/L. The belief that the untreated water is not safe to drink (risk) and that reducing drinking water As would increase home value (instrumental attitude) were identified as significant predictors of mitigating As. Mitigating As exposure is associated with less worry about the As level (affective attitude), possibly because those acting to reduce exposure feel less worried about As. Use of a treatment system specifically was significantly predicted by confidence that one can maintain a treatment system, even if there are additional costs (self-efficacy). An assessment of As treatment systems used by 68 of these households with well water As &gt;10?g/L followed up within August-November 2013 found that 15% of treatment units failed to produce water below As 10?g/L, suggesting that there are continued risks for exposure even after the decision is made to treat.",
Arsenic,1355387,"Urinary biomarkers for chronic arsenic exposure to C57BL/6J mice Abstract: Arsenic has been classified as a human carcinogen based on very strong epidemiological data although the mechanism of its carcinogenicity is still largely unknown. Urinary biomarkers for chronic arsenic exposure would be valuable as an early warning indicator for timely interventions. As part of a 2 year arsenic carcinogenicity study, young female C57BL/6J mice were given drinking water containing 0, 100, 250 and 500 Ag Asv/L as sodium arsenate ad lib for 12 months. Urine was collected every two months including time zero for urinary methylation assay (i.e. speciation of inorganic arsenic and its methylated metabolites) and analyses of other biomarkers. All detectable arsenic species showed strong linear correlation with administered dosage and the methylation patterns were similar in all three groups. No significant changes of methylation pattern were observed over time for neither control nor test groups. Malondialdehyde, an index for lipid perioxidation, was not altered in exposure groups up to 12 months. However, urinary 8-Hydroxy-2V-deoxyguanosine, a biomarker of DNA damage, showed a significant dose response relationship after 8 month of exposure. Urinary coproporphyrin III, an intermediate product of heme biosynthesis, is significantly increased at 8 month. The monitoring of biomarkers will continue for a further 12 months.",
Arsenic,627505,"Socioeconomic status and risk for arsenic-related skin lesions in Bangladesh Abstract: OBJECTIVES: Arsenic contamination of groundwater is a severe public health crisis in Bangladesh, where the population is exposed to arsenic in drinking water through tube wells used for groundwater collection. In this study, we explored the association between socioeconomic status and arsenic toxicity. METHODS: We used baseline data from 11438 men and women who were recruited into the Health Effects of Arsenic Longitudinal Study (HEALS), a prospective cohort study on the health effects of arsenic exposure in Bangladesh. We conducted analyses with logistic regression and generalized estimating equations. RESULTS: We found a strong dose-response association with all measures of arsenic exposure and skin lesions. We also found that the effect of arsenic was modified by land ownership on a multiplicative scale, with an increased risk among non-land owners associated with well water arsenic (P=.04) and urinary total arsenic concentrations (P=.03). CONCLUSIONS: Our study provides insight into potentially modifiable host characteristics and identifies factors that may effectively target susceptible population subgroups for appropriate interventions.",
Arsenic,1373059,"Determination of arsenic by graphite furnace atomic absorption spectrometry combined with liquid-liquid extraction of arsenomolybdic acid Abstract: BIOSIS COPYRIGHT: BIOL ABS. Graphite furnace atomic absorption spectrometry coupled with liquid-liquid extraction was investigated for the determination of ng ml-1 levels of arsenic. Arsenic (III, V) was converted into arsenomolybdic acid in 1 M hydrochloric acid and extracted quantitatively into isobutyl methylketone. The extract was injected into a graphite furnace atomizer and arsenic was determined using the 193.7-nm arsenic line under optimum conditions. By matrix modification, i.e., the formation of the heteropoly ac the loss of arsenic which is apt to occur during the ashing stage was suppressed. When the aqueous to organic phase volume ratio was 2.5:1 (v/v), the sensitivity (1% absorption) and relative standard deviation (n = 10, 1.5 mug of arsenic(III)) were 0.58 ng ml-1 and 2.1%, respectively. The proposed method was applied to the analysis of steel, mine water and river water samples. The results were in good agreement with those obtained by a spectrophotometric procedure.",
Arsenic,1677582,"Optimal treatment for patients with chronic Stanford type B aortic dissection: endovascularly, surgically or both? Abstract: OBJECTIVES: Patients with chronic Stanford type B aortic dissections (TBAD) are traditionally treated medically, but some of the affected thoracic and thoracoabdominal aortic segments progress to large aneurysms with a significant risk of rupture. The purpose of this study is to retrospectively evaluate, with an 'all-comers' approach, the survival and the outcome of patients following thoracic endovascular aortic repair (TEVAR) or conventional open surgery for chronic TBAD as a first-line therapy or a secondary option after failed medical treatment. METHODS: Between January 2000 and May 2010, 80 consecutive patients (59 males, median age 63, inter-quartile range (IQR) 55-69) suffering from chronic TBAD were treated at our institution. Thirty-three were treated medically (Group A, median age: 65, IQR: 58.5-71.5), 32 received TEVAR (Group B, median age: 62, IQR: 54-67.5) and 15 patients underwent conventional open surgery (Group C, median age: 61, IQR: 54-66). The median follow-up was 42 months (range: 0.1-124.7) and 100% complete. RESULTS: There were no significant differences with regard to age, gender and associated comorbidities between the treatment groups. The overall hospital mortality for chronic TBAD was 6.3% (n = 5); in-hospital mortalities for Groups A, B and C were 3.0, 6.2 and 13.4%, respectively. The incidence of major complications, such as paraplegia, malperfusion, renal failure and cardiac arrhythmia, did not significantly differ between the three groups. Postoperative stroke occurred more often after conventional open surgery (Group C: 13.3%; P = 0.07). Reintervention for TBAD pathology was required in Groups A, B and C in 12.1, 28.1 and 0%, respectively (P = 0.03). Secondary open surgery post-TEVAR was required in 7 cases (21.8%) with no postoperative paraplegia. CONCLUSIONS: Open surgery for extensive thoracic and thoracoabdominal repair in chronic TBAD may be performed with acceptable early and mid-term outcomes. TEVAR for aortic complications in patients with chronic dissection may be successfully performed as a first-stage procedure in order to stabilize the patient and serve as a 'bridge' to secondary open surgery. However, close surveillance is mandatory for the timely detection of aneurysm enlargement, malperfusion or impending rupture after TEVAR.",
Arsenic,1030884,"Induction of four proteins in chick embryo cells by sodium arsenite Abstract: Four proteins of Mr = 89,000, 73,000, 35,000, and 27,000 are strongly induced in chick fibroblasts by sodium arsenite. Induction of these proteins is discoordinate as a function of arsenite concentration. Kinetically, all species appear 1 h after exposure to 50 microM arsenite, after 24 and 48 h of exposure, the 27,000 protein is still synthesized extensively, whereas normal cell proteins and the three other induced proteins are greatly reduced. The four proteins are unrelated by tryptic peptide-mapping procedures. Multiple subspecies of p89, p73, and p27 were observed in two-dimensional gels. The subspecies of p73 appear to be related as determined by partial proteolytic maps as are those of p27. Two-dimensional gel analysis of in vitro translation products from rabbit reticulocyte lysates primed with mRNA from uninduced and induced cells reveals that the amount of translatable mRNA specific for these proteins is increase by induction. This increase is attributable to new mRNA synthesis since actinomycin D prevent induction and new bands of RNA (Mr = 0.9 X 10(6) and 1.3 X 10(6)) appear in methyl mercury gels of oligo(dT) selected RNA from induced cells. These bands are assigned to p73 and p89 based on translation of electroeluted RNA from a similar preparative gel. A comparison is made between induction of these proteins and the heat shock response in Drosophilla melanogaster.",
Arsenic,1326884,"Acute arsenite-induced 8-hydroxyguanine is associated with inhibition of repair activity in cultured human cells Abstract: 8-Hydroxyguanine (8-OH-Gua) is one of the major modified bases in DNA produced by oxidative damage. Human lung carcinoma cells (A549) were treated with 0.5-2mM sodium arsenite for 4h. By an immunohistochemical type procedure, 8-OH-Gua was clearly detected in A549 cells using a fluorescence microscope and an increase in the percentage of A549 cells with oxidative DNA damage was observed using flow cytometry. The formation of 8-OH-Gua in DNA was also detected by a HPLC-ECD. A dose-dependent increase in oxidative DNA damage in A549 cells with increasing arsenite concentrations was obtained. Therefore, oxidative stress is induced after arsenite treatment. Furthermore, we also found that arsenite decreased the activity of the 8-OH-Gua repair enzyme, hOGG1 (8-oxoguanine-DNA glycosylase 1) as well as its gene and protein expression. We conclude that the 8-OH-Gua level in cultured human cells increases partly by the generation of reactive oxygen species (ROS) and partly by the influence on hOGG1 expression, followed by the inhibition of the repair activity for 8-OH-Gua.",
Arsenic,1344683,"Inhibition of poly (ADP-Ribose) polymerase-1 in telomerase deficient mouse embryonic fibroblasts increases arsenite-induced genome instability Abstract: <strong>BACKGROUND: </strong>The telomerase enzyme is a viable target for anti-cancer therapy given the innate differences in telomerase activity between tumour cells and normal somatic cells. However, the time lag between telomerase inhibition and telomeres becoming critically short to trigger cell death, allows cancer cells to acquire drug resistance. Inhibition of DNA repair pathways along with telomerase could be an alternative strategy to enhance anti-tumour effects and circumvent the possibility of drug resistance. Poly (ADP-Ribose) Polymerase-1 (PARP-1), an important DNA damage sensor and a DNA repair factor, has important roles in maintaining telomeres and chromosomal stability. In this study, the effects of combined inhibition of PARP-1 and telomerase in mouse embryonic fibroblasts (MEFs) following sodium arsenite exposure (a carcinogen and potent DNA damaging agent), were evaluated.<br /><br /><strong>RESULTS: </strong>Inhibition of PARP in telomerase deficient MEFs induced an increase in arsenite-induced DNA damage as compared to control cells. Combined inhibition also resulted in enhanced genomic instability, demonstrated by elevated micronuclei induction and chromosomal aberrations with decreased cell survival. In addition, telomerase inhibition in PARP-1 deficient MEFs led to greater telomere shortening and increased genomic instability.<br /><br /><strong>CONCLUSIONS: </strong>Our study demonstrated that the co-inhibition of PARP-1 and telomerase in MEFs rendered cells more susceptible to DNA damaging agents. Hence, these results offer support for the use of combined inhibition of PARP-1 and telomerase as a strategy to minimise the problems associated with long-term telomerase inhibition in cancer therapeutics.",
Arsenic,2337195,"Does antenatal testing for morbid obesity affect induction rate or timing of delivery? Abstract: <strong>INTRODUCTION: </strong>Women with morbid obesity (body mass index 40 kg/m or greater) have an increased risk of stillbirth. Therefore, antenatal testing has been initiated. Data are limited evaluating the obstetrical implications of antenatal testing for morbidly obese women. Our objective was to evaluate the risk of induction and the gestational age of delivery in morbidly obese women undergoing antenatal testing.<br /><br /><strong>METHODS: </strong>We performed a retrospective cohort study of women undergoing antenatal testing during 2012 who delivered at our institution. Women were divided into three groups based on antenatal testing indications: group 1: morbid obesity alone, group 2: morbid obesity+comorbidity, group 3: nonmorbid obesity+comorbidity. Our primary outcomes were induction and gestational age of delivery (weeks). Categorical variables were compared with ? analyses and multivariable logistic regression was used to calculate odds and control for confounders.<br /><br /><strong>RESULTS: </strong>Three hundred ninety women were included (group 1=124, group 2=111, group 3=155). The overall induction rate was not significantly different by group (23%, 34%, 34%; P=.08). However, when compared with group 2, group 1 had a lower induction risk (odds ratio [OR] 0.59 [0.34-1.02]), which was significant after controlling for maternal age and race (adjusted OR 0.49 [0.27-0.87]). Group 1 also had a decreased induction risk when compared with group 3 (OR 0.58 [0.34-0.97], adjusted OR 0.49 [0.28-0.85]). There was a significant difference in gestational age of delivery between groups (39.1 weeks in group 1, 38.5 weeks in group 2, 37.9 weeks in group 3, P&lt;.001). Overall cesarean delivery rate was 43% (P=.9).<br /><br /><strong>CONCLUSIONS: </strong>Although it remains unknown whether antenatal testing decreases the stillbirth risk in morbidly obese women, this population does not appear to be at increased risk of morbidity as a result of this intervention. Future studies should evaluate neonatal implications for antenatal testing in this group.",
Arsenic,1704136,Temporal variation in the arsenic and metal accumulation in the maritime pine tree grown on contaminated soils Abstract: ,
Arsenic,1508706,"Occurrence of arsenic impurities in organoarsenics and animal feeds Abstract: Organoarsenics are widely used as excellent feed additives in animal production in the world. Roxarsone (ROX) and arsanilic acid (ASA) are two organoarsenics permitted to be used in China. We collected 146 animal feed samples to investigate the appearance of ROX, ASA, and potential metabolites, including 3-amino-4-hydroxyphenylarsonic acid (3-A-HPA), 4-hydroxyphenylarsonic acid (4-HPA), As(V), As(III), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in feeds. The stability of ROX in both ROX additives and animal feeds was also examined. The results show that 25.4% of the 146 animal feeds contained organoarsenics, with average contents of ROX and ASA as 7.0 and 21.2 mg of As/kg, respectively. Unexpectedly, As(III) and MMA frequently occurred as As impurities in feeds bearing organoarsenics, with higher contents than organoarsenics in some samples. 3-A-HPA, 4-HPA, and DMA were not detected in all samples. ROX and As impurities in both ROX additives and feeds stayed unchanged in the shelf life. It suggests that As impurities in animal feeds bearing organoarsenics should generate from the use of organoarsenics containing As impurities. This constitutes the first report of As impurities in organoarsenics.",
Arsenic,1794813,Evaluation of As(III) and Sb(III) Adsorption to Paddy Soils from Irrigated Rice Fields in Bangladesh Abstract: ,
Arsenic,2337075,"Adsorption of roxarsone by iron (hydr)oxide-modified multiwalled carbon nanotubes from aqueous solution and its mechanisms Abstract: The adsorption of roxarsone by iron (hydr)oxide-modified multiwalled carbon nanotubes (MWCNTs) from aqueous solution and its mechanism were investigated. The amount of roxarsone adsorbed by modified MWCNTs is higher than MWCNTs at the same condition. The results show that the sorption isotherms are nonlinear, and can be well fitted according to the Freundlich and Polanyi-Manes models. The adsorption kinetics could be well described by pseudo-second-order model. Thermodynamic analysis shows that the adsorption of roxarsone on the adsorbents is an exothermic and spontaneous process. Desorption process had no obvious desorption hysteresis phenomenon. The FT-IR and XPS analysis confirmed the loading of iron ions on the MWCNTs, and revealed the involvement of carboxyl groups and iron ions on the adsorption of roxarsone.",
Arsenic,2064273,"Severe Influenza Outbreak in Western Ukraine in 2009 - a molecular-epidemiological study Abstract: Introduction: In the autumn of 2009 the authors participated in a humanitarian operation in Western Ukraine by undertaking an epidemiological investigation of an influenza-like-illness (ILI) in the L'viv Oblast region. Mobile biological survey teams took samples from civilian patients with severe acute respiratory distress syndrome, rapid transportation of the samples, and their molecular analysis in Poland to provide accurate results. Objective: The aim of the study was the molecular and epidemiological analysis of the biological samples collected. Material and Methods: Real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR), multiplex PCR techniques, traditional Sanger Sequencing and classical viral culture methods were used. Results: Among the 124 influenza-like illness cases, ~50% (58) were positive for influenza A virus in WHO-CDC molecular assay, including subtyping. The specimens were further analyzed to confirm results and determine the genetic sequence. Phylogenetically, the nucleotide similarity of both the Ukraine specimens and reference A/California/7/2009 (pH1N1) was 99.2-99.3%. Oseltamivir resistance was not registered. HA1 region characterization showed an overall protein identity of 98.5-99.4%. Conclusions: An unexpected high contribution of influenza A was confirmed among ILI patients, as well as a very limited number of other detected viruses, indicate that the 2009 epidemic in western Ukraine was strongly related to novel influenza A/H1N1. The importance of swift sharing of information and reference laboratories networking in surveillance, as well as serving governments and international agencies in pursuing adequate actions, should be stressed.",
Arsenic,1597387,"Atmospheric Arsenic Deposition in Chiayi County in Southern Taiwan Abstract: Although arsenic contamination of underground water in southern Taiwan is well known, few studies examine atmospheric arsenic deposition in this area, which might be the major source of such pollution to the soil, water, and even underground water. This research focused on the atmospheric arsenic concentration, dry and wet depositions, and the As distribution around Chiayi County, located in the south of Taiwan. Eight sampling sites are used, both upwind and downwind of an area with heavy industrial and human activities. All samples were collected by a PS-1 high volume sampler at each site, pretreated by a digestion process, and further analyzed with an ICP-MS. The results show that the arsenic deposition flux ranged from 65.0 to 473 mu g/m(2)-month in Chiayi County. This deposition flux has no significant seasonal variation, based on the multiple trend results obtained from pooling the dry and wet deposition data. The average dry deposition flux of As ranged from 34 to 161 mu g/m(2)-month during the sampling year, and had the opposite trend to the wind speed. Additionally, the correlations between atmospheric arsenic concentration and PM levels were significant, supported by the low p-value (&lt; 0.01) at a 99% confidence level. Meanwhile, the highly linear correlation between As and PM concentrations was also evaluated. The amount of precipitation was statistically correlated to the wet deposition flux (11.3-414 mu g/m(2)-month with a p-value = 2 x 10(-7) and r-value = 0.9306. Furthermore, the composition of the As mass concentrations in ambient air were dominated by As (V) in both fall (66.4%) and winter (68.9%). According to the GIS spatial analysis of the As concentration in the dry season, from October to March, the As contribution of local emissions were not significant. Consequently, this study indicates that the atmospheric As around Chiayi County might be sourced from the upwind northern area, and mainly deposited through wet scavenging.",
Arsenic,1017832,"Quantitative proteomic analysis reveals the perturbation of multiple cellular pathways in HL-60 cells induced by arsenite treatment Abstract: Arsenic is ubiquitously present in the environment; it is a known human carcinogen and paradoxically it is also a successful drug for the clinical remission of acute promyelocytic leukemia (APL). The cellular responses induced by arsenite treatment have been investigated for years; however, the precise mechanisms underlying its cytotoxicity and therapeutic activity remain unclear. Here we report the use of mass spectrometry together with stable isotope labeling by amino acids in cell culture (SILAC) for the comparative study of protein expression in HL-60 cells that were untreated or treated with a clinically relevant concentration of arsenite. Our results revealed that, among the 1067 proteins quantified in both forward and reverse SILAC measurements, 56 had significantly altered levels of expression induced by arsenite treatment. These included the up-regulation of core histones, neutrophil elastase, alpha-mannosidase as well as the down-regulation of fatty acid synthase and protein phosphatase 1 alpha. We further demonstrated that the arsenite-induced growth inhibition of HL-60 cells could be rescued by treatment with palmitate, the final product of fatty acid synthase, supporting that arsenite exerts its cytotoxic effect, in part, via suppressing the expression of fatty acid synthase and inhibiting the endogenous production of fatty acid. The results from the present study offered important new knowledge for gaining insights into the molecular mechanisms of action of arsenite.",
Arsenic,1252274,"Determination of arsenic in edible fats and oils by focused microwave digestion and atomic fluorescence spectrometer Abstract: A method for the determination of arsenic in edible fats and oils was developed. A half-gram sample was digested with 10 mL sulfuric acid and 5 mL nitric acid by focused microwave digester, and then analyzed by atomic fluorescence spectrometer (AFS). The detection limit of the instrument was at 50 pg/mL. The recovery studies were performed at 0.05, 0.10 and 0.20 m spike levels of arsenic in palm oil, olive oil and lard. The recoveries were in range of 89.8~94.7, 86.3~96.9 and 86.9~91.5%, respectively. Twenty-one market samples of edible fats and oils were analyzed to contain 0.005~0.027 ppm of arsenic.",
Arsenic,628581,"The magnitude of arsenic contamination in groundwater and its health effects to the inhabitants of the Jalangi--One of the 85 arsenic affected blocks in West Bengal, India Abstract: To better understand the magnitude of arsenic contamination in groundwater and its effects on human beings, a detailed study was carried out in Jalangi, one of the 85 arsenic affected blocks in West Bengal, India. Jalangi block is approximately 122 km2 in size and has a population of 215538. Of the 1916 water samples analyzed (about 31% of the total hand tubewells) from the Jalangi block, 77.8% were found to have arsenic above 10 microg l(-1) [the World Health Organization (WHO)-recommended level of arsenic in drinking water], 51% had arsenic above 50 microg l(-1) (the Indian standard of permissible limit of arsenic in drinking water) and 17% had arsenic at above 300 microg l(-1) (the concentration predicting overt arsenical skin lesions). From our preliminary medical screening, 1488 of the 7221 people examined in the 44 villages of Jalangi block exhibit definite arsenical skin lesions. An estimation of probable population that may suffer from arsenical skin lesions and cancer in the Jalangi block has been evaluated comparing along with international data. A total of 1600 biologic samples including hair, nail and urine have been analyzed from the affected villages of Jalangi block and on an average 88% of the biologic samples contain arsenic above the normal level. Thus, a vast population of the block may have arsenic body burden. Cases of Bowen's disease and cancer have been identified among adults who also show arsenical skin lesions and children in this block are also seriously affected. Obstetric examinations were also carried out in this block.",
Arsenic,2278806,"Timing of rabbit antithymocyte globulin induction therapy in kidney transplantation: An observational cohort study Abstract: <strong>BACKGROUND: </strong>Literature on the timing of rabbit antithymocyte globulin (rATG) induction and its effects on kidney transplant outcomes is limited. The manufacturer recommends that the first dose be given intra-operatively, however this may present clinical practice risks and challenges. Our objective was to assess the impact of the timing of the first dose of rATG on kidney transplant outcomes.<br /><br /><strong>METHODS: </strong>Incident kidney transplant recipients (KTR) from January 2002 to December 2009 receiving the first dose of rATG post-operatively (Post, n?=?353) or before reperfusion (Pre, n?=?124) were evaluated. Outcomes assessed included eGFR at 1-year, delta eGFR (12 versus 1 month), and incidence of biopsy-proven acute rejection, graft loss, death, and a composite of the time-to-event outcomes. The impact of timing on outcomes was adjusted for potential confounders and assessed using linear and Cox regression models.<br /><br /><strong>RESULTS: </strong>Among 435 KTR surviving with function to 12 months post-transplant, there was no significant difference in mean estimated glomerular filtration rate or eGFR (55.0 versus 56.7 mL/min, P?=?0.46) and delta eGFR (1.8 versus 0.3 mL/min, P?=?0.40) in Post versus Pre groups, respectively. At a median follow-up of 3 years, the composite endpoint (time to first biopsy-proven acute rejection, graft loss, or death) was similar by timing group (adjusted HR?=?0.94; 95% CI: 0.58, 1.53, P?=?0.81) in the total study population.<br /><br /><strong>CONCLUSIONS: </strong>Timing of rATG had no appreciable impact on clinically relevant endpoints in this study cohort. These results support consideration of more flexible timing of the first dose of rATG induction in KTR.",
Arsenic,732050,"8-Oxoguanine DNA glycosylase and MutY homolog are involved in the incision of arsenite-induced DNA adducts Abstract: Since arsenite is known to induce oxidative DNA damage in human cells, we asked if it induces other types of DNA damage and how the DNA damage is repaired. Treatment of human promyelocytic leukemia NB4 cells with 0.5muM As(2)O(3) for 30 min induced no DNA breaks, as analyzed by a standard comet assay. However, breaks were detected if these cells were then digested with endonuclease III (EnIII), formamidopyrimidine-DNA glycosylase (Fpg), or a nuclear extract (NE) of NB4 cells. Using either H(2)O(2)-Fe-treated nuclei or As(2)O(3)-treated cells, digestion with either NE or EnIII + Fpg generated the same amount of breaks, and subsequent treatment with EnIII + Fpg resulted in no increase in breaks in NE-digested cells and vice versa. The human cell lines, defective in nucleotide excision protein, such as xeroderma pigmentosum (XP) A, XPD, and XPG, excised Ultraviolet C-induced adducts less rapidly than normal fibroblasts, but excised As(2)O(3) adducts at the same rate as the normal cells. Immunodepletion of the NE with antibody against 8-oxoguanine DNA glycosylase (OGG1) or MutY homolog (MYH) decreased the incision of As(2)O(3)-induced adducts, while antibodies against XPA, XPB, XPD, XPF, or XPG, did not. These results suggest that As(2)O(3) induces the formation of only oxidative DNA adducts and that OGG1 and MYH are involved in this incision process.",
Arsenic,1677538,"Gypsum addition to soils contaminated by red mud: Implications for aluminium, arsenic, molybdenum and vanadium solubility Abstract: Red mud is highly alkaline (pH 13), saline and can contain elevated concentrations of several potentially toxic elements (e.g. Al, As, Mo and V). Release of up to 1 million m(3) of bauxite residue (red mud) suspension from the Ajka repository, western Hungary, caused large-scale contamination of downstream rivers and floodplains. There is now concern about the potential leaching of toxic metal(loid)s from the red mud as some have enhanced solubility at high pH. This study investigated the impact of red mud addition to three different Hungarian soils with respect to trace element solubility and soil geochemistry. The effectiveness of gypsum amendment for the rehabilitation of red mud-contaminated soils was also examined. Red mud addition to soils caused a pH increase, proportional to red mud addition, of up to 4 pH units (e.g. pH 7 ? 11). Increasing red mud addition also led to significant increases in salinity, dissolved organic carbon and aqueous trace element concentrations. However, the response was highly soil specific and one of the soils tested buffered pH to around pH 8.5 even with the highest red mud loading tested (33 % w/w); experiments using this soil also had much lower aqueous Al, As and V concentrations. Gypsum addition to soil/red mud mixtures, even at relatively low concentrations (1 % w/w), was sufficient to buffer experimental pH to 7.5-8.5. This effect was attributed to the reaction of Ca(2+) supplied by the gypsum with OH(-) and carbonate from the red mud to precipitate calcite. The lowered pH enhanced trace element sorption and largely inhibited the release of Al, As and V. Mo concentrations, however, were largely unaffected by gypsum induced pH buffering due to the greater solubility of Mo (as molybdate) at circumneutral pH. Gypsum addition also leads to significantly higher porewater salinities, and column experiments demonstrated that this increase in total dissolved solids persisted even after 25 pore volume replacements. Gypsum addition could therefore provide a cheaper alternative to recovery (dig and dump) for the treatment of red mud-affected soils. The observed inhibition of trace metal release within red mud-affected soils was relatively insensitive to either the percentage of red mud or gypsum present, making the treatment easy to apply. However, there is risk that over-application of gypsum could lead to detrimental long-term increases in soil salinity.",
Arsenic,1358205,Mortality patterns among hard rock gold miners exposed to an asbestiform mineral Abstract: ,
Arsenic,2278301,"Food for Thought: A Critical Overview of Current Practical and Conceptual Challenges in Trace Element Analysis in Natural Waters Abstract: The practical and conceptual challenges faced by the analysis of trace elements present in natural waters are not merely, as is often thought, an endless race towards lower detection limits or to the development of techniques allowing the determination of any possible chemical species formed by all chemical elements. Rather, as discussed in this paper, they include the development of (i) robust, cheap, and reliable methods that could also be used by laypeople (the experience gained in the development of field kits for As is discussed as an example from which similar developments for other elements may be drawn); (ii) more environmentally-friendly methods (the current guiding criteria probably being too simplistic); and (iii) methods making it possible to follow diel concentration changes and sharp concentration variations caused by the probable increase of heavy rainfall events. This paper also claims that neither the measurement of total concentrations (reliable methods are lacking for many elements of the periodic table of trace elements, as illustrated through the cases of Bi, Te, and Sb), nor chemical speciation analysis, are as mature as often thought. In particular, chemical speciation studies demand the development of a better, comprehensive conceptual framework. A trial is carried out to lay the basis of such a framework.",
Arsenic,656660,"Low level exposure to monomethyl arsonous acid-induced the over-production of inflammation-related cytokines and the activation of cell signals associated with tumor progression in a urothelial cell model Abstract: Human bladder cancer has been associated with chronic exposure to arsenic. Chronic exposure of an immortalized non-tumorigenic urothelial cell line (UROtsa cells) to arsenicals has transformed these cells to a malignant phenotype, but the involved mechanisms are not fully understood. Chronic inflammation has been linked with cancer development mainly because many pro-inflammatory cytokines, growth factors as well as angiogenic chemokines have been found in tumors. In this study the chronology of inflammatory cytokines production was profiled in UROtsa cells chronically exposed to the toxic arsenic metabolite, monomethylarsonous acid [50 nM MMA(III)] to know the role of inflammation in cell transformation. Acute 50 nM MMA(III) exposure induced over-production of many pro-inflammatory cytokines as soon as 12 h after acute exposure. The same cytokines remain over-regulated after chronic exposure to 50 nM MMA(III), especially after 3 mo exposure. At 3 mo exposure the sustained production of cytokines like IL-1, IL-6, IL-8 and TNF is coincident with the appearance of characteristics associated with cell transformation seen in other arsenic-UROtsa studies. The sustained and increased activation of NFkappaB and c-Jun is also present along the transformation process and the phosphorylated proteins p38 MAPK and ERK 1/2 are increased also through the time line. Taken together these results support the notion that chronic inflammation is associated within MMA(III)-induced cell transformation and may act as a promoting factor in UROtsa cell transformation.",
Arsenic,1354406,"Alpha-methylacyl-CoA racemase (AMACR/P504S) protein expression in urothelial carcinoma of the upper urinary tract correlates with tumour progression Abstract: Alpha-methylacyl-CoA racemase (AMACR/P504S) is a useful biomarker of prostate cancer. We evaluated the expression of AMACR in upper urinary tract urothelial carcinomas with respect to associations with tumour stage, grade and metastasis-free survival. A total of 268 tumours were investigated immunohistochemically using a tissue microarray technique. AMACR expression was noted in 127 of 261 (48.7%) evaluated tumours and was associated with high tumour stage [58 of 139 (41.7%) pTa/pT1 vs. 69 of 122 (56.6%) pT2-pT4, P=0.019] and high tumour grade [44 of 137 (32.1%) low vs. 83 of 124 (66.9%) high grade, P&lt;0.001]. In addition, AMACR expression was associated with the presence of tumour necrosis (P&lt;0.001) and marked stromal desmoplasia (P=0.0026). This correlation indicates that increased AMACR expression might be related to hypoxia-induced changes in cancer cell metabolism, such as increased dependence on fatty acid oxidation for energy generation. Progressive disease was observed in 73 of 183 (39.9%) patients with solitary invasive carcinomas and was associated with AMACR expression (P=0.017). Multivariate analysis, however, proved only pT-stage &gt;1 (P&lt;0.001) and high tumour grade (P&lt;0.001) to be independent predictors of patient outcome. In conclusion, AMACR expression correlated with advanced tumour stage and grade and may serve as an additional prognostic indicator in upper urinary tract urothelial cancer.",
Arsenic,2347744,"Toxicological Study of Arsenic-Based Polyoxometalate with In Vivo Antiviral Activity Abstract: The aim of this study is to detect toxicity of arsenic in [KAs4W40O140](27)- (PM-3) in vivo by determining arsenic metabolic pattern of PM-3. The results show that arsenic, in both NaAsO2 and PM-3 groups, is metabolized and excreted quickly after intraperitoneal injection; no significant difference is observed among all arsenic species levels between PM-3 and NaAsO2 group in urine; mice that were given NaAsO2 show a higher concentration of monomethylarsenate (MMA) and a lower secondary, methylation index (SMI) compared with PM-3 group in blood; the primary methylation index (PMI) in the livers and kidneys of PM-3 group is significantly higher than that of NaAsO2 group. These results indicate that PM-3 does not show a lower methylation capacity than that of NaAsO2, providing a basis for clinical application of PM-3.",
Arsenic,1353121,"Induction of the heme oxygenase-1 gene by metalloporphyrins Abstract: Induction of expression of heme oxygenase-1 (HO-1) has been studied in primary cultures of chick embryo liver cells and in the LMH line of avian hepatoma cells. Cells were transiently transfected with selected constructs containing portions of the 5'-untranslated (promoter) region of the HO-1 gene linked to luciferase as reporter gene. LMH cells that had been stably transfected with selected wild type or mutant constructs were also studied. Metalloporphyrins, especially Fe protoporphyrin (heme) and Co protoporphyrin strongly induced luciferase expression in both types of transfected cells. Low concentrations of Zn mesoporphyrin, an inhibitor of HO activity, exerted a synergistic effect on heme-, but not Co protoporphyrin-dependent induction. The antioxidant and &amp;bond;SH donor N-acetyl cysteine had little effect on the metalloporphyrin-dependent inductions of HO-1, in contrast to its marked inhibitory effect on the sodium arsenite-dependent induction of the HO-1 gene. Deletional analysis showed that the key element(s) required for the metalloporphyrin-dependent induction of HO-1 is located between -3.6 and -5.6 kb upstream of the transcription starting point. Data from electrophoretic mobility shift and site-directed mutagenesis experiments excluded a role for consensus AP-1 binding elements at -1576, -3647, or -4578 in the inductions produced by heme or Co protoporphyrin.",
Arsenic,1337924,"The chemical composition of smokeless tobacco: A survey of products sold in the United States in 2006 and 2007 Abstract: Selected toxicant concentrations and other chemical measures have been determined for 43 U.S. smokeless tobacco products sold in 2006 and 2007. Products evaluated included moist snuff, dry snuff, loose leaf, plug, dissolvable and snus tobacco brands. Reference products available for scientific research purposes and eleven Swedish products were also evaluated and compared to the commercial products studied. Chemical endpoints determined included benzo[a]pyrene (B[a]P), N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N-Nitrosodimethylamine (NDMA), nitrite, cadmium, lead, arsenic, nickel, chromium, chloride, water, pH and nicotine. Different toxicant profiles were observed for the products studied, with snus tobacco brands generally containing relatively low concentrations of B[a]P and tobacco specific nitrosamines (TSNAs) compared to other moist snuffs. Smokeless tobacco reference product toxicant profiles were similar to corresponding commercial products, with the exception of the TSNA content of the dry snuff reference material. TSNA concentrations observed for all commercial products were lower than historically reported values, likely reflecting changes in product shelf life, tobacco curing practices and, possibly, product blend formulations during the last 20-30years. The survey results summarized provide a temporal point of comparison with future data anticipated from FDA &quot;harmful and potentially harmful constituents in tobacco products&quot; reporting.",
Arsenic,2149195,"Coupling predicted model of arsenic in groundwater with endemic arsenism occurrence in Shanxi Province, Northern China Abstract: Statistical modeling has been used to predict high risk area of arsenic (As) hazard, but information about its application on endemic arsenism is limited. In this study, we aim to link the prediction model with population census data and endemic arsenicosis in Shanxi Province, Northern China. 23 explanatory variables from different sources were compiled in the format of grid at 1km resolution in a GIS environment. Logistic regression was applied to describe the relationship between binary-coded As concentrations data and the auxiliary predictors. 61 endemic arsenism villages were geo-located and combined with output maps of the prediction model. Linear regression was used to identify the relationship between arsenicosis occurrence rate and predictive As probability at village level. Our results show that 6 explanatory environmental variables were significantly contributed to the final model. Area of 3000km(2) was found to have high risk of As concentrations above 50?gL(-1). The linear regression indicates that 13% of the variation in arsenicosis occurrence rate can be predicted using predictive probability of As concentration above 50?gL(-1) in Shanxi Province. These results suggest that As prediction model may be helpful for identifying As-contaminated area and endemic arsenism village.",
Arsenic,1519196,Formation Characteristics of a Self-catalyzed GaAs Nanowire without a Ga Droplet on Si(111) Abstract: ,
Arsenic,1070390,"Toxic Metals in Breast Milk Samples from Ankara, Turkey: Assessment of Lead, Cadmium, Nickel, and Arsenic Levels Abstract: Toxic metals are one of the significant groups of chemical contaminants that humans are exposed to by oral, inhalation, and dermal routes. Exposure to these chemicals begins with intrauterine life and continues during lactation period at the first years of life. Breastfeeding has a much more special place than other nutrition options for infants. However, when possibility of contaminant transfer by breast milk is considered, its safety and quality is essential. Regarding infant and mother health and limited number of information on this field in Turkey, measuring contamination levels in breast milk is important. Therefore, in the present study, lead (Pb), cadmium (Cd), nickel (Ni), and arsenic (As) levels were measured by atomic absorption spectrometry in 64 breast milk samples obtained from mothers from Ankara, Turkey. Pb and Ni levels in breast milk samples were found to be 391.45?±?269.01 ?g/l and 43.94?±?33.82 ?g/l (mean ± SD), respectively. Cd was found only in one of 64 samples, and the level was 4.62 ?g/l. As level was below the limit of quantification (LOQ, 7.6 ?g/l) in all samples. These findings will accurately direct strategies and solutions of protection against contaminants in order to reduce their levels in biological fluids.",
Arsenic,1234209,"Arsenite and cadmium, but not chromium, induce NAD(P)H:quinone oxidoreductase 1 through transcriptional mechanisms, in spite of post-transcriptional modifications Abstract: NAD(P)H:quinone oxidoreductase (Nqo1)-mediated detoxification of quinones plays a critical role in cancer prevention. Metals alter the carcinogenicity of AhR ligands, such as TCDD, by modulating the induction of Nqo1, but the mechanism(s) remain unresolved. To decipher the molecular mechanisms involved in the alteration of Nqo1, we analyzed the effect of the metals As3+ (5 microM), Cd2+ (5 microM), and Cr6+ (25 microM) on the transcriptional activation of the Nqo1 gene and post-transcriptional modifications, in Hepa 1c1c7 cells. Both As3+ and Cd2+ induced Nqo1 mRNA in a time-dependent manner and potentiated TCDD-induced Nqo1 mRNA. Cr6+ on the other hand, completely inhibited the induction of Nqo1 mRNA by TCDD. The induction of Nqo1 mRNA by the metals was completely inhibited with the DNA transcription inhibitor actinomycin-D, indicating a requirement for de novo mRNA synthesis for the induction. Furthermore, the protein synthesis inhibitor cycloheximide decreased Nqo1 mRNA induction, suggesting a role for a labile protein in the transcriptional induction of Nqo1 mRNA by metals. Surprisingly, all three metals decreased Nqo1 mRNA stability while having no effect on Nqo1 protein half-life. Meanwhile, As3+ and Cd2+ induced constitutive Nqo1 activity and potentiated the induction by increasing concentrations of TCDD. On the other hand, Cr6+ inhibited inducible Nqo1 activity. It is apparent that metals alter Nqo1 expression at the transcriptional level, through a labile protein-mediated pathway.",
Arsenic,2337258,"Electrochemically Induced Oxidative Precipitation of Fe(II) for As(III) Oxidation and Removal in Synthetic Groundwater Abstract: Mobilization of Arsenic in groundwater is primarily induced by reductive dissolution of As-rich Fe(III) oxyhydroxides under anoxic conditions. Creating a well-controlled artificial environment that favors oxidative precipitation of Fe(II) and subsequent oxidation and uptake of aqueous As can serve as a remediation strategy. We reported a proof of concept study of a novel iron-based dual anode system for As(III) oxidation and removal in synthetic groundwater. An iron anode was used to produce Fe(II) under iron-deficient conditions, and another inert anode was used to generate O2 for oxidative precipitation of Fe(II). For 30 min's treatment, 6.67 ?M (500 ?g/L) of As(III) was completely oxidized and removed from the solution during the oxidative precipitation process when a total current of 60 mA was equally partitioned between the two anodes. The current on the inert anode determined the rate of O2 generation and was linearly related to the rates of Fe(II) oxidation and of As oxidation and removal, suggesting that the process could be manipulated electrochemically. The composition of Fe precipitates transformed from carbonate green rust to amorphous iron oxyhydroxide as the inert anode current increased. A conceptual model was proposed for the in situ application of the electrochemically induced oxidative precipitation process for As(III) remediation.",
Arsenic,1339129,"Effects of chronic exposure to arsenic and estrogen on epigenetic regulatory genes expression and epigenetic code in human prostate epithelial cells Abstract: Chronic exposures to arsenic and estrogen are known risk factors for prostate cancer. Though the evidence suggests that exposure to arsenic or estrogens can disrupt normal DNA methylation patterns and histone modifications, the mechanisms by which these chemicals induce epigenetic changes are not fully understood. Moreover, the epigenetic effects of co-exposure to these two chemicals are not known. Therefore, the objective of this study was to evaluate the effects of chronic exposure to arsenic and estrogen, both alone and in combination, on the expression of epigenetic regulatory genes, their consequences on DNA methylation, and histone modifications. Human prostate epithelial cells, RWPE-1, chronically exposed to arsenic and estrogen alone and in combination were used for analysis of epigenetic regulatory genes expression, global DNA methylation changes, and histone modifications at protein level. The result of this study revealed that exposure to arsenic, estrogen, and their combination alters the expression of epigenetic regulatory genes and changes global DNA methylation and histone modification patterns in RWPE-1 cells. These changes were significantly greater in arsenic and estrogen combination treated group than individually treated group. The findings of this study will help explain the epigenetic mechanism of arsenic- and/or estrogen-induced prostate carcinogenesis.",
Arsenic,1343511,"Differences in the epigenetic regulation of MT-3 gene expression between parental and Cd+2 or As+3 transformed human urothelial cells Abstract: <strong>BACKGROUND: </strong>Studies have shown that metallothionein 3 (MT-3) is not expressed in normal urothelium or in the UROtsa cell line, but is expressed in urothelial cancer and in tumors generated from the UROtsa cells that have been transformed by cadmium (Cd+2) or arsenite (As+3).The present study had two major goals. One, to determine if epigenetic modifications control urothelial MT-3 gene expression and if regulation is altered by malignant transformation by Cd+2 or As+3. Two, to determine if MT-3 expression might translate clinically as a biomarker for malignant urothelial cells released into the urine.<br /><br /><strong>RESULTS: </strong>The histone deacetylase inhibitor MS-275 induced MT-3 mRNA expression in both parental UROtsa cells and their transformed counterparts. The demethylating agent, 5-Aza-2'-deoxycytidine (5-AZC) had no effect on MT-3 mRNA expression. ChIP analysis showed that metal-responsive transformation factor-1 (MTF-1) binding to metal response elements (MRE) elements of the MT-3 promoter was restricted in parental UROtsa cells, but MTF-1 binding to the MREs was unrestricted in the transformed cell lines. Histone modifications at acetyl H4, trimethyl H3K4, trimethyl H3K27, and trimethyl H3K9 were compared between the parental and transformed cell lines in the presence and absence of MS-275. The pattern of histone modifications suggested that the MT-3 promoter in the Cd+2 and As+3 transformed cells has gained bivalent chromatin structure, having elements of being &quot;transcriptionally repressed&quot; and &quot;transcription ready&quot;, when compared to parental cells. An analysis of MT-3 staining in urinary cytologies showed that a subset of both active and non-active patients with urothelial cancer shed positive cells in their urine, but that control patients only rarely shed MT-3 positive cells.<br /><br /><strong>CONCLUSION: </strong>The MT-3 gene is silenced in non-transformed urothelial cells by a mechanism involving histone modification of the MT-3 promoter. In contrast, transformation of the urothelial cells with either Cd+2 or As+3 modified the chromatin of the MT-3 promoter to a bivalent state of promoter readiness. Urinary cytology for MT-3 positive cells would not improve the diagnosis of urothelial cancer, but might have potential as a biomarker for tumor progression.",
Arsenic,1327432,"Ectopic expression of interleukin-1 receptor type II enhances cell migration through activation of the pre-interleukin 1alpha pathway Abstract: Expression of interleukin-1 receptor type II (IL1R2), a decoy receptor for pro-inflammatory interleukin 1 (IL-1), is enhanced by chronic exposure of the human uroepithelial cell line HUC-1 to arsenite. To explore the function of IL1R2, we ectopically expressed IL1R2 in HUC-1 cells. IL1R2 overexpression results in changes in cell morphology, actin rearrangement, and promoted cell migration. Ectopic expression of IL1R2 specifically blocked exogenous IL-1beta signaling but increased expression of the precursor form of IL-1alpha (pIL-1alpha) and its downstream targets, including interleukin 6 (IL-6), interleukin 8 (IL-8), and type I collagen alpha1 (COL1A1). However, depleting gene expression using small RNA interference specific to either pIL-1alpha or COL1A1, but not IL-6 or IL-8, significantly attenuated the migration of IL1R2-overexpressing cells. Furthermore, IL1R2 overexpression was associated with enhanced expression of Smad-interacting protein 1 (SIP-1) and reduced expression of E-cadherin. Because SIP-1 is a repressor of COL1A1-induced E-cadherin expression, the present results suggest that IL1R2 overexpression is likely through activation of the pIL-1alpha pathway to enhance cell migration.",
Arsenic,656864,"Skin cancers in chronic arsenic toxicity--a study of predictive value of some proliferative markers Abstract: Prolonged exposure to arsenic contaminated water produces various clinical features, cutaneous features e.g. melanosis, keratosis and cancers being very common. Evaluation of such lesions by proliferative markers can provide useful information in regards to the biological behaviour of the lesions. Thus, cases with high proliferative status can be ominous sign for development of cancers. We studied skin biopsy of 42 cases. These were evaluated with AgNOR score and PCNA stain, in addition to H & E examination. Here, invasive cancer cases had mean AgNOR score of 3.56, those with severe dysplasia had 3.0, moderate and mild dysplasia scored 1.73, benign changes had mean score of 1.35 while normal control cases had 1.08. PCNA index in cancers was above 50, that of severe dysplasia 25-30, mild to moderate dysplasia 1.0-5.0, those with benign changes 0.5 -1.0 and normal control had LI of less than 0.5%. PCNA has the advantage of less chance of observer error over AgNOR stain.",
Arsenic,1339442,"?-catenin involvement in arsenite-induced VEGF expression in neuroblastoma SH-SY5Y cells Abstract: Arsenic is a widespread contaminant in the environment especially in drinking water. Although it is a known carcinogen in human, the mechanism by which arsenic induces carcinogenesis is not well understood. Among several effects of arsenic, it has been suggested that arsenic-induced vascular endothelial growth factor (VEGF) expression plays a critical role in arsenic carcinogenesis. In the present study, we demonstrated that arsenite induced VEGF expression in neuroblastoma SH-SY5Y cells without induction of HIF-1?, a well-known transcriptional activator for VEGF suggesting that arsenite-induced VEGF expression in SH-SY5Y cells may not require HIF-1? activation. It has been reported that VEGF expression is regulated by multiple transcription factors including ?-catenin. We therefore investigated whether ?-catenin was involved in arsenite-induced VEGF expression in SH-SY5Y cells. Treatment of arsenite caused ?-catenin accumulation in the nucleus. Additionally, arsenite treatment decreased the activity of GSK3, an enzyme that phosphorylates and targets ?-catenin for degradation by proteasome, without activation of its upstream kinase, Akt. Inhibition of PI3K/Akt which negatively regulates GSK3 activity by LY294002 resulted in a decrease in arsenite-mediated ?-catenin nuclear accumulation, and VEGF expression. These results suggested that ?-catenin plays a role in arsenite-induced VEGF in SH-SY5Y cells, and the induction of ?-catenin by arsenite is mediated by inhibition of GSK3 without activating its upstream kinase Akt. © © 2012 Wiley Periodicals, Inc. Environ Toxicol, 2012.",
Arsenic,1597402,Removal of Arsenic from Aqueous Solutions Using Zirconium Oxyhydrate Embedded Fe3O4 Nanoparticle Abstract: ,
Arsenic,1242308,"Eating artificially ripened fruits is harmful Abstract: Presently, the whole world is emphasizing on malnutrition, food safety and health security. Several programmes have also been launched in this regard. The year 2008-09 was declared as the 'Food Safety and Quality Year' by the Government of India. Most fruit sellers use Calcium carbide for ripening the fruits. Calcium carbide is extremely hazardous to the human body as it contains traces of arsenic and phosphorus. It is banned in many countries of the world, but it is freely used in India, Pakistan, Bangladesh, Nepal and other countries. Thus we are at risk of short-term and long-term health effects simply by eating fruits that are induced to ripen. This article discusses the common yet most important fact related to fruits - how nutrition changes over to malnutrition?.",
Arsenic,134650,"Arsenic toxicity and potential mechanisms of action Abstract: Exposure to the metalloid arsenic is a daily occurrence because of its environmental pervasiveness. Arsenic, which is found in several different chemical forms and oxidation states, causes acute and chronic adverse health effects, including cancer. The metabolism of arsenic has an important role in its toxicity. The metabolism involves reduction to a trivalent state and oxidative methylation to a pentavalent state. The trivalent arsenicals, including those methylated, have more potent toxic properties than the pentavalent arsenicals. The exact mechanism of the action of arsenic is not known, but several hypotheses have been proposed. At a biochemical level, inorganic arsenic in the pentavalent state may replace phosphate in several reactions. In the trivalent state, inorganic and organic (methylated) arsenic may react with critical thiols in proteins and inhibit their activity. Regarding cancer, potential mechanisms include genotoxicity, altered DNA methylation, oxidative stress, altered cell proliferation, co-carcinogenesis, and tumor promotion. A better understanding of the mechanism(s) of action of arsenic will make a more confident determination of the risks associated with exposure to this chemical.",
Arsenic,2064307,"Naturally occurring contaminants in the piedmont and blue ridge crystalline-rock aquifers and piedmont early mesozoic basin siliciclastic-rock aquifers, Eastern United States, 1994-2008 Abstract: Groundwater quality and aquifer lithologies in the Piedmont and Blue Ridge Physiographic Provinces in the eastern United States vary widely as a result of complex geologic history. Bedrock composition (mineralogy) and geochemical conditions in the aquifer directly affect the occurrence (presence in rock and groundwater) and distribution (concentration and mobility) of potential naturally occurring contaminants, such as arsenic and radionuclides, in drinking water. To evaluate potential relations between aquifer lithology and the spatial distribution of naturally occurring contaminants, the crystalline-rock aquifers of the Piedmont and Blue Ridge Physiographic Provinces and the siliciclastic-rock aquifers of the Early Mesozoic basin of the Piedmont Physiographic Province were divided into 14 lithologic groups, each having from 1 to 16 lithochemical subgroups, based on primary rock type, mineralogy, and weathering potential. Groundwater-quality data collected by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program from 1994 through 2008 from 346 wells and springs in various hydrogeologic and land-use settings from Georgia through New Jersey were compiled and analyzed for this study. Analyses for most constituents were for filtered samples, and, thus, the compiled data consist largely of dissolved concentrations. Concentrations were compared to criteria for protection of human health, such as U.S. Environmental Protection Agency (USEPA) drinking water maximum contaminant levels and secondary maximum contaminant levels or health-based screening levels developed by the USGS NAWQA Program in cooperation with the USEPA, the New Jersey Department of Environmental Protection, and Oregon Health & Science University. Correlations among constituent concentrations, pH, and oxidation-reduction (redox) conditions were used to infer geochemical controls on constituent mobility within the aquifers. Of the 23 trace-element constituents evaluated, arsenic, manganese, and zinc were detected in one or more water samples at concentrations greater than established human health-based criteria. Arsenic concentrations typically were less than 1 microgram per liter (µg/L) in most groundwater samples; however, concentrations of arsenic greater than 1 µg/L frequently were detected in groundwater from clastic lacustrine sedimentary rocks of the Early Mesozoic basin aquifers and from metamorphosed clastic sedimentary rocks of the Piedmont and Blue Ridge crystalline rock aquifers. Groundwater from these rock units had elevated pH compared to other rock units evaluated in this study. Of the nine samples for which arsenic concentration was greater than 10 µg/L, six were classified as oxic and three as anoxic, and seven had pH of 7.2 or greater. Manganese concentrations typically were less than 10 µg/L in most samples; however, 8.3 percent of samples from the Piedmont and Blue Ridge crystalline-rock aquifers and 3.0 percent of samples from the Early Mesozoic basin siliciclastic rock aquifers had manganese concentrations greater than the 300-µg/L health-based screening level. The positive correlation of manganese with iron and ammonia and the negative correlation of manganese with dissolved oxygen and nitrate are consistent with the reductive dissolution of manganese oxides in the aquifer. Zinc concentrations typically were less than 10 µg/L in the groundwater samples considered in the study, but 0.4 percent and 5.5 percent of the samples had concentrations greater than the health-based screening level of 2,000 µg/L and one-tenth of the health-based screening level, respectively. The mean rank concentration of zinc in groundwater from the quartz-rich sedimentary rock lithologic group was greater than that for other lithologic groups even after eliminating samples collected from wells constructed with galvanized casing. Approximately 90 percent of 275 groundwater samples had radon-222 concentrations that were greater than the proposed alternative maximum contaminant level of 300 picocuries per liter. In contrast, only 2.0 percent of 98 samples had combined radium (radium-226 plus radium-228) concentrations greater than the maximum contaminant level of 5.0 picocuries per liter, and 0.6 percent of 310 samples had uranium concentrations greater than the maximum contaminant level of 30 µg/L. Radon concentrations were highest in the Piedmont and Blue Ridge crystalline-rock aquifers, especially in granite, and elevated median concentrations were noted in the Piedmont Early Mesozoic basin aquifers, but without the extreme maximum concentrations found in the crystalline rocks (granites). Although the siliciclastic lithologies had a greater frequency of elevated uranium concentrations, radon and radium were commonly detected in water from both siliciclastic and crystalline lithologies. Uranium concentrations in groundwater from clastic sedimentary and clastic lacustrine/evaporite sedimentary lithologic groups within the Early Mesozoic basin aquifers, which had median concentrations of 3.6 and 3.1 µg/L, respectively, generally were higher than concentrations for other siliciclastic lithologic groups, which had median concentrations less than 1 µg/L. Although 89 percent of the 260 samples from crystalline-rock aquifers had uranium concentrations less than 1 µg/L, 0.8 percent had uranium concentrations greater than the 30-µg/L maximum contaminant level, and 6.5 percent had concentrations greater than 3 µg/L.",
Arsenic,2345656,"?-NH4Fe(HAsO4)2 Abstract: The title compound ?-ammonium iron(III) bis-[hydro-gen arsenate(V)], ?-NH4Fe(HAsO4)2 (or poly[ammonium bis-(?-hydro-gen arsenato)ferrate(III)], {NH4[Fe(HAsO4)2]} n ), syn-the-sized hydro-thermally, is isostructural with NH4Fe(HPO4)2. Condensation of the hydro-gen arsenate groups with FeO6 coordination octa-hedra via common corners results in an overall three-dimensional framework containing inter-connected channels parallel to the a-, b- and c-axis directions. The NH4 (+) cations are located in three inter-secting tunnels, which is promising as an ion exchange. Hydrogen bonding of the types O-H?O and N-H?O consolidates the packing of the structure. The distortion of the coordination polyhedra is analyzed by means of the effective coordination number and distortion indices. Structural relationships with other compounds of general formula M (I) M (III)[HXO4)]2 (X = P, As) are discussed.",
Arsenic,1342759,"Arsenic levels in crops irrigated with water containing MSMA Abstract: Mature plants of tomato (Lycopersicon esculentum Mill. 'Super Sioux'), cucumber (Cucumis sativas L. 'Early pickling'), and pinto bean (Pbaseolus vulgaris L.), in small field plots, were exposed once to sprinkler or furrow irrigation water containing 0.11 kg/ha or 1.12 kg/ha MSMA (monosodium methane arsonate). Concentrations of MSMA in water were about 0.22 ppmw and 2.2 ppmw for the two rates, respectively. Samples of crops and soil were subsequently analyzed for elemental arsenic content by colorimetric and atomic absorption methods. Arsenic residues were higher, compared to controls, only in crops exposed to MSMA applied in sprinkler irrigation. Average arsenic levels were highest in tomatoes exposed to 2.2 ppmw MSMA by sprinkler irrigation, and after 30 and 45 days were 0.26 ppm and 0.35 ppm, respectively. Average arsenic levels in sprinkler- irrigated crops ranged from double to triple the arsenic levels in control (untreated) crops. Atomic absorption was more sensitive than the colorimetric method and could detect smaller differences in arsenic content of samples. The average arsenic residues in soil varied from 1 to 3 ppm, but the differences could not be attributed to treatment with MSMA.",
Arsenic,1337701,"Integrated co-regulation of bacterial arsenic and phosphorus metabolisms Abstract: Arsenic ranks first on the US Environmental Protection Agency Superfund List of Hazardous Substances. Its mobility and toxicity depend upon chemical speciation, which is significantly driven by microbial redox transformations. Genome sequence-enabled surveys reveal that in many microorganisms genes essential to arsenite (AsIII) oxidation are located immediately adjacent to genes coding for functions associated with phosphorus (Pi) acquisition, implying some type of functional importance to the metabolism of As, Pi or both. We extensively document how expression of genes key to AsIII oxidation and the Pi stress response are intricately co-regulated in the soil bacterium Agrobacterium tumefaciens. These observations significantly expand our understanding of how environmental factors influence microbial AsIII metabolism and contribute to the current discussion of As and P metabolism in the microbial cell.",
Arsenic,2149336,"Removal of arsenic compounds with peat, peat-based and synthetic sorbents Abstract: Arsenic contamination of waters is a global problem; therefore, new approaches for its removal are needed. Peat, peat modified with iron compounds, iron humates and polymeric cation exchangers modified with iron were prepared and tested for sorption of arsenic compounds in comparison with weakly basic anionites. The highest sorption capacity was observed when peat sorbents modified with iron compounds were used. Sorption of different arsenic speciation forms onto iron-modified peat sorbents was investigated as a function of pH and temperature. It was established that sorption capacity increases with a rise in temperature, and the calculation of sorption process thermodynamic parameters indicates the spontaneity of sorption process and its endothermic nature.",
Arsenic,62138,Elevated sister chromatid exchange rate in lymphocytes of subjects treated with arsenic Abstract: An elevated sister chromatid exchange (SCE) rate was found in the lymphocytes of six patients treated with arsenic. All had stigmata of arsenic use as well as biopsy-proven skin cancers. The arsenic exposed patients had a mean of 14.00 SCE/mitosis while 44 normal controls had a mean of 5.8 SCE/mitosis. Chromosome breakage analysis revealed no difference between the two groups. SCE rate has been shown to be elevated in a variety of systems where cell cultures or experimental animals were exposed to known mutagens and carcinogens. We suggest that the relationship carcinogen exposure-elevated SCE rate-cancer may also be valid in humans treated with arsenic.,
Arsenic,1386622,"Possible environmental, occupational, and other etiologic factors for Parkinson's disease: A case-control study in Germany Abstract: BIOSIS COPYRIGHT: BIOL ABS. In a case-control study, we investigated the possible etiologic relevance to Parkinson's disease (PD) of rural factors such as farming activity, pesticide exposures, well-water drinking, and animal contacts; toxicologic exposures such as wood preservatives, heavy metals, and solvents; general anesthesia; head trauma; and differences in the intrauterine environment. We recruited 380 patients in nine German clinics, 379 neighborhood control subjects, and 376 regional control subjects in the largest case-control study investigating such factors and collected data in structured personal interviews using conditional logistic regression to control for educational status and cigarette smoking. The latter was strongly inversely associated with PD. There were significantly elevated odds ratios (OR) for pesticide use, in particular, for organochlorines and alkylated phosphates, but no association was present between PD and other rural factors. A significantly elevated OR was pres",
Arsenic,1031761,"A novel 40-kDa protein induced by heat shock and other stresses in mammalian and avian cells Abstract: When HeLa cells were exposed to heat shock or other stresses, a 40-kDa protein (p40) was induced in addition to the classical heat shock proteins with molecular sizes of 110-, 90-, 70-, and 47-kDa. The p40 was induced not only by heat shock but by arsenite and 2-azetidine carboxylic acid. Also, it was induced in rat, mouse and chick cells by these stresses. The p40 was a basic protein (pI divided by 9.2) as judged by two-dimensional gel electrophoresis. To our knowledge, p40 is a novel heat shock protein in mammalian and avian cells.",
Arsenic,1015880,"Selenium, arsenic, and mercury in fish inhabiting a fly ash exposure gradient: Inter-specific bioaccumulation patterns and elemental associations Abstract: Releases from coal ash impoundments can be a significant source of trace elements to the aquatic environment. In the present study, whole body concentrations of arsenic, mercury, and selenium in various fish species inhabiting streams receiving a gradient of fly ash exposure are reported. High exposure sites had elevated water concentrations of arsenic, molybdenum, selenium, and sulfate. Fish were collected during two seasons in 2007. Mercury concentrations in all fish samples were low (range?=?0.012-0.99?mg/kg dry wt); highest arsenic concentrations occurred in fish from high exposure sites. Whole body selenium concentrations were low at reference sites but increased as the magnitude of fly exposure increased. For all sites combined, a significant (r2?=?0.60) correlation was observed between the geometric mean of each species' whole body selenium concentration and log-transformed water selenium concentration. A significant inverse relationship was apparent with log-transformed whole body mercury and selenium concentrations (r2?=?0.56 for all species and sites combined), suggesting that high tissue selenium levels antagonistically regulated mercury bioaccumulation. Sunfish (Lepomis sp.) from high and medium-exposure sites had significantly higher selenium body residues, but significantly lower mercury, relative to fish from low exposure and reference sites. Ninety percent of fish from high exposure sites had a surplus of selenium whereas all fish from reference sites had Se/Hg molar ratios?&lt;?1.0. These ratios increased as water selenium increased. Where fish have moderate to high exposure to fly ash-influenced water, selenium tissue levels can be expected to be elevated (as well as arsenic, in some cases), but tissue mercury concentrations will likely be low. Environ. Toxicol. Chem. © 2012 SETAC.",
Arsenic,1353108,Compositions of Xylem Fluid of Arsenic-Stressed Barley Seedlings: A Measurement with PIXE System and HPLC Abstract: ,
Arsenic,2347554,"Invertebrate grazers affect metal/metalloid fixation during litter decomposition Abstract: Plant litter and organic sediments are main sinks for metals and metalloids in aquatic ecosystems. The effect of invertebrates as key species in aquatic litter decomposition on metal/metalloid fixation by organic matter is described only for shredders, but for grazers as another important animal group less is known. Consequently, a laboratory batch experiment was conducted to examine the effect of invertebrate grazers (Lymnaea stagnalis L.) on metal/metalloid fixation/remobilization during aquatic litter decomposition. It could be shown that invertebrate grazers facilitate significantly the formation of smaller sizes of particulate organic matter (POM), as shown previously for invertebrate shredders. The metal/metalloid binding capacity of these smaller particles of POM is higher compared to leaf litter residuals. But element enrichment is not as high as shown previously for the effect by invertebrate shredders. Invertebrate grazers enhance also the mobilization of selected elements to the water, in the range also proven for invertebrate shredders but different for the different elements. Nonetheless invertebrate grazers activity during aquatic litter decomposition leads to a metal/metalloid fixation into leaf litter as part of sediment organic matter. Hence, the effect of invertebrate grazers on metal/metalloid fixation/remobilization contrasts partly with former assessments revealing the possibility of an enhanced metal/metalloid fixation.",
Arsenic,1018780,"Arsenic levels in hair of workers in a semiconductor fabrication facility Abstract: This study examined the relationship between total arsenic levels in hair of employees in a semiconductor fabrication facility and job responsibility, a surrogate variable for arsenic exposure potential. Maintenance personnel who regularly worked in equipment cleaning areas were assumed to have higher potential for occupational exposure than other employees. Occipital scalp hair samples were collected from 30 maintenance personnel, supervisors, and equipment engineers with high, medium, and low potential for exposure and from 26 administrative employees. Total arsenic in hair was measured by atomic absorption spectroscopy with hydride generation. Workplace air and wipe samples were analyzed to verify differing exposure potential in fabrication and administrative areas. Subjects completed written questionnaires to identify possible nonoccupational sources of arsenic. Mean hair arsenic in two of the three groups working in or near fabrication areas was slightly higher but not statistically different from that of administrative controls. Eliminating smokers, only the maintenance group regularly assigned to fabrication areas was higher than administrative controls but still not statistically different. A regression analysis of all factors indicated that sex, tapwater consumption, and dietary habits were significant contributors to arsenic in hair. Trends among these groups were consistent with expected exposure potential, although not dramatically different from controls. Main study conclusions were that (1) nonoccupational sources of arsenic can be expected to contribute more to hair levels in employees than that observed in this particular semiconductor work environment, where safe work practices were believed to be followed; and (2) monitoring should be considered in this industry to identify employees experiencing chronic, low-level arsenic exposures only if the facility also examines nonoccupational sources of exposure. Further study is needed to correlate hair arsenic level with internal body burden of those species of arsenic primarily responsible for its toxic effects.",
Arsenic,2298680,"Seasonal perspective of dietary arsenic consumption and urine arsenic in an endemic population Abstract: Exposure to arsenic in arsenic endemic areas is most remarkable environmental health challenges. Although effects of arsenic contamination are well established, reports are unavailable on probable seasonal variation due to changes of food habit depending on winter and summer seasons, especially for endemic regions of Nadia district, West Bengal. Complete 24-h diets, drinking-cooking water, first morning voided urine samples, and diet history were analyzed on 25 volunteers in arsenic endemic Chakdah block of Nadia district, once in summer followed by once in winter from the same participants. Results depicted no seasonal variation of body weight and body mass index. Arsenic concentration of source drinking and cooking water decreased (p?=?0.04) from 26 ?g L(-1) in summer to 6 ?g L(-1) in winter season. We recorded a seasonal decrease of water intake in male (3.8 and 2.5 L day (-1)) and female (2.6 and 1.2 L day(-1)) participants from summer to winter. Arsenic intake through drinking water decreased (p?=?0.04) in winter (29 ?g day(-1)) than in summer (100 ?g day(-1)), and urinary arsenic concentration decreased (p?=?0.018) in winter (41 ?g L(-1)) than in summer (69 ?g L(-1)). Dietary arsenic intake remained unchanged (p?=?0.24) over the seasons. Hence, we can infer that human health risk assessment from arsenic needs an insight over temporal scale.",
Arsenic,2149299,"Amending soils with phosphate as means to mitigate soil lead hazard: a critical review of the state of the science Abstract: Ingested soil and surface dust may be important contributors to elevated blood lead (Pb) levels in children exposed to Pb contaminated environments. Mitigation strategies have typically focused on excavation and removal of the contaminated soil. However, this is not always feasible for addressing widely disseminated contamination in populated areas often encountered in urban environments. The rationale for amending soils with phosphate is that phosphate will promote formation of highly insoluble Pb species (e.g., pyromorphite minerals) in soil, which will remain insoluble after ingestion and, therefore, inaccessible to absorption mechanisms in the gastrointestinal tract (GIT). Amending soil with phosphate might potentially be used in combination with other methods that reduce contact with or migration of contaminated soils, such as covering the soil with a green cap such as sod, clean soil with mulch, raised garden beds, or gravel. These remediation strategies may be less expensive and far less disruptive than excavation and removal of soil. This review evaluates evidence for efficacy of phosphate amendments for decreasing soil Pb bioavailability. Evidence is reviewed for (1) physical and chemical interactions of Pb and phosphate that would be expected to influence bioavailability, (2) effects of phosphate amendments on soil Pb bioaccessibility (i.e., predicted solubility of Pb in the GIT), and (3) results of bioavailability bioassays of amended soils conducted in humans and animal models. Practical implementation issues, such as criteria and methods for evaluating efficacy, and potential effects of phosphate on mobility and bioavailability of co-contaminants in soil are also discussed.",
Arsenic,2279318,"Adaptive optics enhanced direct laser writing of high refractive index gyroid photonic crystals in chalcogenide glass Abstract: Chiral gyroid photonic crystals are fabricated in the high refractive index chalcogenide glass arsenic trisulfide with an adaptive optics enhanced direct laser writing system. The severe spherical aberration imparted when focusing into the arsenic trisulfide is mitigated with a defocus decoupled aberration compensation technique that reduces the level of aberration that must be compensated by over an order of magnitude. The fabricated gyroids are shown to have excellent uniformity after our adaptive optics method is employed, and the transmission spectra of the gyroids are shown to have good agreement with numerical simulations that are based on a uniform and diffraction limited fabrication resolution.",
Arsenic,2337254,"Quantitative Study of As (V) and As (III) Interaction with Mangrove DNA by Molecular Fluorescence Spectroscopy Abstract: This study describes the in vitro study of (1:1) one step nucleophilic displacement ([Formula: see text]) of phosphate by heavier anion arsenate and arsenite in the DNA of arsenic ridden Sundarban mangroves. Mangrove DNA was found to give rise to a broad fluorescence and its integrated fluorescence intensity was enhanced on addition of As (V) and As (III), respectively. Analyses of the fluorescence parameter showed adequacy of 1:1 model to describe substitution of phosphate of mangrove DNA chain exiplex by arsenate and arsenite with equilibrium constant (log Kc) ranging between 4.19 and 4.32 for As (V), and between 3.77 and 3.89 for As (III) at pH 7 and 25°C. In the cases, the melting temperature (Tm) and reassociation rate constant of mangrove DNA was increased on treatment with As (V) and As (III). It is suggested that heavier ion arsenate and arsenite may substitute phosphate in natural DNA.",
Arsenic,2088596,"A cost-effective system for in-situ geological arsenic adsorption from groundwater Abstract: An effective and low-cost in-situ geological filtration system was developed to treat arsenic-contaminated groundwater in remote rural areas. Hangjinhouqi in western Hetao Plain of Inner Mongolia, China, where groundwater contains a high arsenic concentration, was selected as the study area. Fe-mineral and limestone widely distributed in the study area were used as filter materials. Batch and column experiments as well as field tests were performed to determine optimal filtration parameters and to evaluate the effectiveness of the technology for arsenic removal under different hydrogeochemical conditions. A mixture containing natural Fe-mineral (hematite and goethite) and limestone at a mass ratio of 2:1 was found to be the most effective for arsenic removal. The results indicated that Fe-mineral in the mixture played a major role for arsenic removal. Meanwhile, limestone buffered groundwater pH to be conducive for the optimal arsenic removal. As(III) adsorption and oxidation by iron mineral, and the formation of Ca-As(V) precipitation with Ca contributed from limestone dissolution were likely mechanisms leading to the As removal. Field demonstrations revealed that a geological filter bed filled with the proposed mineral mixture reduced groundwater arsenic concentration from 400?g/L to below 10?g/L. The filtration system was continuously operated for a total volume of 365,000L, which is sufficient for drinking water supplying a rural household of 5 persons for 5years at a rate of 40L per person per day.",
Arsenic,627074,"Arsenic induces oxidative DNA damage in mammalian cells Abstract: Although arsenic is a well-established human carcinogen, the underlying carcinogenic mechanism(s) is not known. Using the human-hamster hybrid (A(L)) cell mutagenic assay that is sensitive in detecting mutagens that induce predominately multilocus deletions, we showed previously that arsenite is indeed a potent gene and chromosomal mutagen and that oxyradicals may be involved in the mutagenic process. In the present study, the effects of free radical scavenging enzymes on the cytotoxic and mutagenic potential of arsenic were examined using the AL cells. Concurrent treatment of cells with either superoxide dismutase or catalase reduced both the cytotoxicity and mutagenicity of arsenite by an average of 2-3 fold, respectively. Using immunoperoxidase staining with a monoclonal antibody specific for 8-hydroxy-2'-deoxyguanosine (8-OHdG), we demonstrated that arsenic induced oxidative DNA damage in A(L) cells. This induction was significantly reduced in the presence of the antioxidant enzymes. Furthermore, reducing the intracellular levels of non-protein sulfhydryls (mainly glutathione) using buthionine S-R-Sulfoximine increased the total mutant yield by more than 3-fold as well as the proportion of mutants with multilocus deletions. Taken together, our data provide clear evidence that reactive oxygen species play an important causal role in the genotoxicity of arsenic in mammalian cells.",
Arsenic,1936184,"Procedia Earth and Plantetary Science Microbiological processes affecting the hydrogeochemistry of arsenic-contaminated groundwater in the Datong Basin, northern China Abstract: ",
Arsenic,2347623,"Sodium arsenite induced changes in survival, growth, metamorphosis and genotoxicity in the Indian cricket frog (Rana limnocharis) Abstract: Arsenic contamination of the environment is a matter of great concern. Understanding the effects of arsenic on aquatic life will act as biological early warning system to assess how arsenic could shape the biodiversity in the affected areas. Rapid decline in amphibian population in recent decades is a cause of major concern. Over the years, amphibians have been recognized as excellent bio-indicators of environmental related stress. In the present study, we examined the toxic and genotoxic effects of sodium arsenite in the tadpoles of the Indian cricket frog (Rana limnocharis). Sodium arsenite at different concentrations (0, 50, 100, 200 and 400?gL(-1)) neither induced lethality nor significantly altered body weight at metamorphosis. However, it accelerated the rate of metamorphosis at higher concentrations, reduced body size (snout-vent length) and induced developmental deformities such as loss of limbs. Besides, at concentration ranges between 100 and 400?gL(-1), sodium arsenite induced statistically significant genotoxicity at 24, 48, 72 and 96h of the exposure in a concentration-dependent manner. However, it did not show time effects as the highest frequency was found between 48 and 72h which remained steady subsequently. The genotoxicity was confirmed by comet assay in the whole blood cells. These findings suggest that arsenic at environmentally relevant concentrations has significant sub-lethal effects on R.limnocharis, which may have long-term fitness consequence to the species and may have similar implications in other aquatic life too.",
Arsenic,1031546,"Comparative toxicity of arsenic compounds and their accumulation in invertebrates and fish Abstract: The toxicity of arsenic III, arsenic V, sodium dimethyl arsenate, and disodium methyl arsenate to stoneflies, snails, amphipods, and trout, and the bioaccumulation of these compounds were studied during a 28-day flow-through test. Daphnia magna were exposed for 21 days in static tests to determine life-cycle effects. All animals were exposed to concentrations of approximately 100 and 1000 microgram/L (as arsenic) of each of the compounds. Arsenic III, the most toxic compound, caused a significant reduction in the survival of amphipods at 1000 microgram As/L after seven days. None of the compounds significantly affected the survival of other test species after 28 days or reduced young production in Daphnia after 14 days of exposure. The concentration of accumulated arsenic in stoneflies, snails, and Daphnia was as much as 131, 99, and 219 times greater than the water concentration, whereas amphipods and rainbow trout contained arsenic residues similar to the controls. Residues in stoneflies, snails, and Daphnia exposed to 1000 microgram As/L were higher than those in animals exposed to 100 microgram As/L, but appeared to reach a steady state after 14 days. Total arsenic accumulation was greatest in organisms exposed to inorganic arsenic, particularly at 100 microgram/L.",
Arsenic,1340672,"Phosphorylation of histone H3 at serine 10 has an essential role in arsenite-induced expression of FOS, EGR1 and IL8 mRNA in cultured human cell lines Abstract: Trivalent inorganic arsenite [iAs(III)] is known to alter the expression of a number of genes associated with transcription and cell proliferation, which was thought to be one of the possible mechanisms of arsenical carcinogenesis. However, the detailed mechanisms underlying iAs(III) induction of changes in gene expression are not fully understood. Here we examine the role of histone H3 phosphorylation at serine 10 (Ser(10) ) in gene regulation when the cells were treated with iAs(III). Among the 34 genes tested, iAs(III) induced mRNA expression of JUN, FOS, EGR1, HMOX1, HSPA1A, IL8, GADD45A, GADD45B and GADD153. Phosphorylation of histone H3 Ser(10) was induced by iAs(III) in interphase cells, and was effectively blocked by the ERKs pathway inhibitor (U0126). U0126 treatment significantly reduced constitutive mRNA expression of FOS and EGR1, and dramatically suppressed the induction of FOS, EGR1 and IL8 mRNA in iAs(III)-treated cells. The other genes, which were induced by iAs(III), were not affected by U0126 treatment. When the histone H3 nonphosphorylatable mutant of serine 10 (S10A) was overexpressed in cells, iAs(III) induction of FOS, EGR1and IL8 expression was significantly decreased as compared with wild-type cells. The other genes induced by iAs(III) were not changed in S10A cells nor by U0126 treatment. In addition, S10A cells were more resistant to iAs(III) cytotoxicity. These results indicated that the phosphorylation of histone H3 at Ser(10) through the ERKs pathway in interphase cells is an important regulatory event for iAs(III)-mediated gene expression. Aberrant gene expression seems to be an important cause of cytotoxicity and may have some relation to iAs(III) carcinogenicity. Copyright © 2012 John Wiley &amp; Sons, Ltd.",
Arsenic,1251545,"Identification of a 66 kD heat shock protein (HSP) induced in M-14 human melanoma cells by severe hyperthermic treatment Abstract: Following severe hyperthermic treatment M-14 cells synthesize at high rate a new protein of about 66 kD, in addition to the three well known major HSPs (HSP 28, HSP 70 and HSP 90). This 66 kD protein is constitutively expressed at low levels and its rate of synthesis is not enhanced by mild hyperthermic exposures (40 degrees C for 2-4 h; 42 degrees C for 1-3 h), sufficient to induce the three major HSPs. The 66 kD protein is induced whenever the thermal dose administered to cells attains a threshold, roughly corresponding to a 50% reduction in survival. The 66 kDa protein is not induced by a variety of compounds (disulfiram, arsenate, cadmium) able to elicit a stress response in M-14 cells, as indicated by enhanced synthesis of the three major HSPs. Once induced by a treatment at 45 degrees C for 15 min, the rate of synthesis of the 66 kD protein remains above the control level for 16-20 h during recovery from the stress, while the synthesis of HSP 70 is shut off between 8 and 12 h. Immunoblotting and immunoprecipitation studies showed that the 66 kD protein shares immunological determinant(s) with HSP 70. Pulse-chase experiments demonstrated that the 66 kD protein is not a degradation product or a late post-transcriptional modification of HSP 70. It is proposed that the 66 kD protein is a previously unrecognized heat shock protein (HSP 66), characterized by an unusually high threshold for its induction.",
Arsenic,1070456,"Microtubules as a critical target for arsenic toxicity in lung cells in vitro and in vivo Abstract: To understand mechanisms for arsenic toxicity in the lung, we examined effects of sodium m-arsenite (As³?) on microtubule (MT) assembly in vitro (0-40 µM), in cultured rat lung fibroblasts (RFL6, 0-20 µM for 24 h) and in the rat animal model (intratracheal instillation of 2.02 mg As/kg body weight, once a week for 5 weeks). As³? induced a dose-dependent disassembly of cellular MTs and enhancement of the free tubulin pool, initiating an autoregulation of tubulin synthesis manifest as inhibition of steady-state mRNA levels of ?I-tubulin in dosed lung cells and tissues. Spindle MT injuries by As³? were concomitant with chromosomal disorientations. As³? reduced the binding to tubulin of [³H]N-ethylmaleimide (NEM), an -SH group reagent, resulting in inhibition of MT polymerization in vitro with bovine brain tubulins which was abolished by addition of dithiothreitol (DTT) suggesting As³? action upon tubulin through -SH groups. In response to As³?, cells elevated cellular thiols such as metallothionein. Taxol, a tubulin polymerization agent, antagonized both As³? and NEM induced MT depolymerization. MT-associated proteins (MAPs) essential for the MT stability were markedly suppressed in As³?-treated cells. Thus, tubulin sulfhydryls and MAPs are major molecular targets for As³? damage to the lung triggering MT disassembly cascades.",
Arsenic,2345794,"Monitoring of non-destructive sampling strategies to assess the exposure of avian species in Jiangsu Province, China to heavy metals Abstract: To assess the exposure of avian species in Jiangsu Province, China to eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), the flight feathers, eggshells and feces of total ten avian species (including four herons, four cranes, one stork and one gull) were collected during March to May in 2012. The total concentrations of As, Cd and Hg were measured by Atomic Fluorescence Spectrometer; Cr, Cu, Ni, Pb and Zn were measured by inductively coupled plasma optical emission spectrometer. The determined concentrations of Cr (3.94, 1.33-8.30 mg kg(-1)), Cu (15.02, 7.34-35.53 mg kg(-1)) and Zn (134.66, 77.26-242.25 mg kg(-1)) in fresh feathers and Cd (7.93, 7.44-9.12 mg kg(-1)), Ni (22.74, 19.38-24.71 mg kg(-1)), Pb (85.06, 78.72-91.95 mg kg(-1)) and Zn (63.54, 55.82-72.14 mg kg(-1)) in eggshells were higher than the mean values of other reported data, indicating a considerable heavy metal pollution status in local area. Comparing to the heavy metal levels in early historic feathers (1992-2000), a significant elevation of concentrations has been observed in recent bird feathers. For feathers of Grus japonensis, the heavy metal concentrations increased by 19-267%. This increased tendency was consistent with local GDP (Gross Domestic Products) development. The anthropogenic economic activity especially industrial development may be a critical reason that caused the increase of heavy metal levels in local avian species.",
Arsenic,628025,"The effects of gestational arsenic exposure and dietary selenium deficiency on selenium and selenoenzymes in maternal and fetal tissues in mice Abstract: Although toxicological and metabolic interactions of arsenic (As) and selenium (Se) have been suggested by epidemiolgical literatures, the past experimental studies mostly focused on acute, high-dose interaction, leaving the long-term, low-dose interaction unexplored. In the present study pregnant mice, fed either Se-deficient or adequate (0 or 5 micromol Se/kg diet, respectively) diet, were given oral gavage of sodium arsenite (0 or 58 micromol/kg per day; chosen as less than half of the fetotoxic dose in this protocol) from gestational day (GD) 7-16. The levels of As and Se as well as five selenoenzymes (glutathione peroxidase (GPx), thioredoxin reductase (TRxR), and type-I, -II and -III iodothyronine deiodinases (DI-I, -II and -III) were examined on GD17 in the tissues of dams and of fetus. The Se-deficient mice showed significantly enhanced accumulation of As compared to the Se-adequate mice in maternal liver (increased by 48%) and fetal brain (by 31%). Although no direct evidence of the enhanced toxicity in the Se-deficient group was obtained, the As exposure affected the levels of Se and selenoenzymes, an effect which was more discernible in Se-deficient group. Although most of theses changes were mild or moderate, the DI-II activity in Se-deficient fetal brain showed a drastic four-fold increase by As exposure, suggesting a possible disturbance of thyroid hormone environment in the fetus. These data suggested that apparently non-toxic, in utero dose of As, showed enhanced accumulation when combined with Se-deficiency and could affect the metabolism/kinetics of Se in fetal brain, which might result in developmental toxicity in mice.",
Arsenic,1936155,Arsenic Mobility and Speciation in a Gleysol with Petrogleyic Properties: A Field and Laboratory Approach Abstract: ,
Arsenic,732084,"Metabolism and excretion of orally administered dimethylarsinic acid in the hamster Abstract: We administered a single po dose of dimethylarsinic acid ( DMAA ) to hamsters by stomach tube and determined the in vivo accumulation of the arsenic and its excretion in the urine and feces. It was shown that a part of the DMAA was further methylated to a trimethylarsenic compound (TMA). During the 24 hr following the administration of DMAA , a total of 80% was excreted in the urine and feces: 45% in the urine (made up of 67.9% DMAA and 32.0% TMA), and 34.7% in the feces (almost completely made up of DMAA but no TMA). The findings show that DMAA and the TMA are rapidly excreted and do not accumulate in the body.",
Arsenic,1348070,"NDRG3 is an androgen regulated and prostate enriched gene that promotes in vitro and in vivo prostate cancer cell growth Abstract: NDRG3 belongs to the N-myc down-regulated gene (NDRG) family that contains 4 paralogs: NDRG1, -2, -3 and -4. The function of NDRG3 and its relationship to cancer has not been studied. We herein report our examination of the expression and biological roles of NDRG3 in prostate cancers. We showed that NDRG3 expression is enriched in testis and prostate using gene expression data derived from massively parallel signature sequencing from 33 different human organs. We further showed that NDRG3 is expressed in both epithelial prostate cancer cells and prostatic stromal cells at both mRNA and proteins levels. We demonstrated that NDRG1 is significantly up-regulated by androgen in LNCaP cells. Over-expression of NDRG3 in stably transfected PC-3 cells increased their growth rates and migration capabilities when compared to parental or mock empty vector transfected PC-3 cells. In addition, we found that overexpresson of NDRG3 promoted the growth of xenograft tumors in nude mice. Finally, we found that NDRG3 expression was detected in 58.6% (41/70) of prostate cancer specimens compared to 13.2% (5/38) of benign prostatic hyperplasia specimens by immunohistochemistry. We showed by microarray and by RT-PCR that NDRG3 overexpression up-regulates the expression of many angiogenic chemokines including CXCL1 (chemokine ligand 1), CXCL3 (chemokine ligand 3) and CXCL5 (chemokine ligand 5), which may increase angiogenesis of tumors. Taken together, these results demonstrate that NDRG3 is a tumor promoter, the overexpression of which may contribute to the malignant phenotype of tumors.",
Arsenic,1030868,"Hemodialysis clearance of arsenic Abstract: We studied the clearance of arsenic by hemodialysis in two patients with acute sodium arsenite intoxication and acute renal failure. Blood arsenic concentration fell considerably with dialysis. The dialysance of arsenic ranged between 76 and 87 mL/min. Total arsenic removal by 4 h of hemodialysis exceeded its 24 hr urinary excretion while renal function was impaired. With improvement of renal function, urinary arsenic excretion increased remarkably and dialysis treatments were discontinued. Based on these result, hemodialysis is a useful adjunct in the treatment of acute arsenic poisoning with concomitant renal failure.",
Arsenic,736229,"Arsenic metabolites affect expression of the neurofilament and tau genes: an in-vitro study into the mechanism of arsenic neurotoxicity Abstract: Neurological studies indicate that the central (CNS) and peripheral nervous system (PNS) may be affected by arsenic (As). As-exposed patients show significantly lower nerve conduction velocities (NCVs) in their peripheral nerves in comparison to healthy subjects. As may play a role in the disruption of neuroskeletal integrity, but the mechanisms by which it exerts a toxic effect on the peripheral and central nervous system are still unclear. In the present study, we examined the neurotoxic effects of various arsenic metabolites (iAs(III), iAs(V), MMA(V) and DMA(V)) on two different cell lines derived from the peripheral (ST-8814) and central (SK-N-SH) nervous system. The effects of the arsenic metabolites were examined on the relative quantification levels of the cytoskeletal genes, neurofilament-light (NEFL), neurofilament-medium (NEF3), neurofilament-heavy (NEFH) and microtubule-associated protein-tau (MAPT), using real-time PCR. Our results show that iAs(III) and iAs(V) have no significant effects on either cell lines. On the other hand, MMA(V) and DMA(V) cause significant changes in expression levels of NEF3 and NEFL genes, while the expression level of the NEFH gene is significantly increased in both cell lines.",
Arsenic,1579360,"Optimal parameters for bioleaching of realgar using Acidithiobacillus ferrooxidans under different growth conditions and mathematical analysis Abstract: Bioleaching, a long-standing technology in hydrometallurgy, has been applied to the field of pharmaceuticals. Here, the bacterial leaching of realgar as a novel preparation method was investigated using Acidithiobacillus ferrooxidans BY-3 (A. ferrooxidans BY-3). We evaluated the effects of a range of crucial operational parameters, including temperature, pH, bacterial population, ferrous iron concentration, and pulp density, on the efficiency of the bioleaching process. Moreover, a conversion algorithm based on linear regression was developed for analyzing the extraction of arsenic. The optimized bioleaching parameters obtained by mathematical analysis were in good agreement with the experimental data, indicating that the model was suitable for design of a realgar bioleaching process.",
Arsenic,1936024,"Natural decrease of dissolved arsenic in a small stream receiving drainages of abandoned silver mines in Guanajuato, Mexico Abstract: Arsenic release from the abandoned mines and its fate in a local stream were studied. Physicochemical parameters, metals/metalloids and arsenic species were determined. One of the mine drainages was found as a point source of contamination with 309 ?g L(-1) of dissolved arsenic; this concentration declined rapidly to 10.5 ?g L(-1) about 2 km downstream. Data analysis confirmed that oxidation of As(III) released from the primary sulfide minerals was favored by the increase of pH and oxidation reduction potential; the results obtained in multivariate approach indicated that self-purification of water was due to association of As(V) with secondary solid phase containing Fe, Mn, Ca.",
Arsenic,1337834,"Trace elements in two marine fish species during estuarine residency: Non-essential versus essential Abstract: Trace element levels in fish are of particular interest, owing the potential risk to human health. In accordance, juveniles of Dicentrarchus labrax and of Liza aurata were sampled and arsenic, cadmium, chromium, selenium and zinc were determined in the muscle. The levels of trace elements in muscle demonstrated to be similar for both species and sites, with the exception of selenium levels at reference, which seemed to be higher in D. labrax. Moreover, apart from arsenic levels in muscle, all elements were in conformity with the existent regulatory guidelines for fish consumption. The dietary intake of each element was also calculated, with arsenic and selenium showing intakes above the recommended dietary allowances. Nevertheless, no arsenic speciation was carried out and thus no accurate risk evaluation could be established. Additionally, selenium levels never exceeded the dietary allowances more than five times, which are considered safe.",
Arsenic,1019232,"Occupational exposures and lung cancer in Buenos Aires, Argentina Abstract: The main objective of this study was to analyze the risks associated with occupational exposures in an industrializing country where lung cancer is the primary neoplastic cause of death in men. A full occupational history was collected through interviewing 199 men with lung cancer and 393 control subjects. Exposure to arsenic, asbestos, chromium, dust, nickel, and polynuclear aromatic hydrocarbons was assessed by means of a job-exposure matrix. Elevated odds ratios were observed for employment in the alcoholic beverages industry (5.2; 95% confidence interval [CI], 1.1 to 23.1), sawmills and wood mills (4.8; 95% CI, 1.2 to 19.0), water transport (3.3; 95% CI, 1.1 to 12.1), and chemicals/plastics manufacturers (1.9; 95% CI, 1.1 to 3.3). A small, non-significant increased risk was observed after long-term exposure to arsenic and chromium, with a dose-response for chromium. Although some of the present results may result from chance, most are consistent with those of previous investigations in other countries.",
Arsenic,1021595,"Low-level groundwater arsenic exposure impacts cognition: A project FRONTIER study Abstract: Arsenic is a ubiquitous environmental toxin with known neurological consequences. Few studies, however, have investigated groundwater arsenic concentrations and cognition among adults and elders. In the study described in this article, the authors examined the potential link between cognitive functioning and low concentrations of arsenic in drinking water. Arsenic concentrations were estimated by the Geographic Information System approach (GIS-arsenic) for 299 rural-dwelling adults and elders. Cognition was assessed with Folstein Mini-Mental State Examination (MMSE). Those in the relatively high GIS-arsenic exposure (&gt; 10.0 microg/L) group had significantly lower MMSE scores than those in the low GIS-arsenic exposure (&lt; or = 10.0 microg/L) group (p &lt; .03). The number of years of education was significantly lower in those in the high GIS-arsenic group(s) than in those in the low GIS-arsenic group (p &lt; .05). These results suggest that poorer cognitive functioning and lower education levels were associated with higher (though still low-level) GIS-arsenic levels in this rural adult cohort.",
Arsenic,325898,"Synergism in immunotoxicological effects due to repeated combined administration of arsenic and lead in mice Abstract: Arsenic and lead are considered potent human hazards because of their neoplastic outcomes; increasing epidemiologic evidence indicates a link between heavy metal exposure and health risk. Since health risks of singly administered metals are well-established, in the present study we determined whether simultaneous repeated multimetal (arsenic + lead) exposure influences the development of immunotoxicity in mice exposed (in vivo) to lead acetate (10 mg/kg b.w.) and sodium arsenite (0.5 mg/kg b.w.) simultaneously. We report that in vivo multimetal exposure alters cell morphology, inhibits cell adhesion, nitric oxide release, intracellular killing ability, chemotactic migration, myeloperoxidase release, bacterial clearance from blood and spleen and increases DNA fragmentation. On measuring bacterial density in blood and spleen after 0, 24, 48 and 72 h post infection (with Staphylococcus aureus MC524) in control and multimetal treated groups, bacterial load showed delayed clearance from blood and spleen in the multimetal exposed group. We also found that in vivo exposure to the multimetal caused a decrease in cell adhesion, indicated by a fall in absorbance at 570 nm with respect to control. Exposure to multimetal led to morphological changes in macrophages, since more deformed cells were obtained in repeated combined exposure to arsenic and lead compared to control. Nitric oxide, which has a potent microbicidal activity in macrophages, was found to be released in fewer amounts in the multimetal exposed group from that of control group. It was observed that the viability of bacteria gradually decreased in control macrophage with time, whereas, in macrophages of multimetal exposed mice, the viability of S. aureus gradually increased. Chemotactic migration of splenic macrophages significantly decreased in the multimetal exposed group from that of control. Lysosomal enzyme release from splenic macrophages decreased upon simultaneous exposure to arsenic and lead, as is evident from the decrease in myeloperoxidase release in multimetal group from that in control. That the structural integrity of splenic macrophages is decreased in the multimetal exposed group is also evident from the enhanced percentage of DNA fragmentation after multimetal exposure, suggesting apoptotic death of splenic macrophage. Intracellular viable bacteria in the splenic macrophage from multimetal exposed group was 89.16Â±3.54% while that from control group was 49.19Â±1.16%, whereas single metal exposed groups showed a bacterial viability of 69.6Â±2.45% and 71.71Â±1.89% in arsenic and lead treated groups respectively. What is essentially noteworthy from the observed results is that lead and arsenic causes a greater immunotoxic effect when administered together as multimetal than when singly administered. Simultaneous exposure to lead and arsenic appears to be additive as is further established from the isobologram constructed by plotting the concentration of arsenic against the concentration of lead at which effect (in this case myeloperoxidase release) remained constant, a convex line showing synergism was demonstrated. The present study reports a definite synergistic trend of immunotoxicity during simultaneous exposure to arsenic and lead, that is, a multimetal challenge, as compared to the effects of independent exposure to them.",
Arsenic,1519062,"Oxidative stress indicators and trace element concentrations in tissues of mako shark (Isurus oxyrinchus) Abstract: Liver, kidney and muscle from juvenile mako sharks (Isurus oxyrinchus) were collected in Baja California Sur. Lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As) concentrations were determined by atomic absorption spectrophotometry. The production of superoxide radical (O2(•-)) was measured as an indicator of reactive oxygen species production; lipid peroxidation (TBARS) and protein carbonyl levels were quantified as indicators of oxidative damage, and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) was assessed as indicator of antioxidant defenses. Two discriminant functions separated muscle from liver and kidney samples. Cd concentration was lower in muscle than in kidney (p&lt;0.05) and Hg concentration was higher in muscle than in liver and kidney (p&lt;0.05). Although GR and SOD activities were higher, oxidative damage (TBARS and carbonyl protein levels) was also higher in kidney (p&lt;0.05). SOD activity, TBARS levels, and Cd and Hg concentration were the set of predictors with significant relevance during tissue discrimination. Tissue metabolism, physiology of the organisms and environmental factors may be related to the differences in trace elements and oxidative stress indicators found in muscle, liver and kidney of the mako shark.",
Arsenic,1597416,"Groundwater arsenic contamination risk prediction using GIS and classification tree method Abstract: Groundwater arsenic contamination is a serious health and environmental problem in Bangladesh. Sources or origin of this heavy metal is known to be natural but the process through which it is being released is poorly understood. In quest of mitigation of the problem it is important to predict area of probable contamination before it causes any damage to human health. In this research an attempt has been made to develop arsenic contamination risk map using a combination of classification tree and GIS technology. Six factors, which might have relation with arsenic contamination, namely geology, soil reaction (pH), elevation, soil organic matter, soil iron and proximity to river were selected as predictor variables. Prediction model was developed using classification algorithm of data mining technology in MATLAB using 80% training data. The developed classification trees were then validated using 20% test dataset. The best tree is found at pruning level 6 with cross validation accuracy result of 78.25%. The classification tree prediction model shows a complex relation of arsenic and the predictors. However, the root classifiers of the classification tree were found to be the surface elevation factor followed by geology. The best tree obtained from cross validation process was used to create the arsenic risk map in GIS environment. The developed risk map is found to be very close to reality where 87.9% of the data were found to be correctly predicted. The research shows that supported by geochemical process the surface elevation of an area determines the degree of accumulation of arsenic in the groundwater.",
Arsenic,1070429,"Adjusting for Urinary Creatinine Overestimates Arsenic Concentrations in Diabetics Abstract: BACKGROUND/AIMS: Arsenic (As) is linked to insulin resistance in animal studies, but the effect of low-level As exposure on the prevalence of diabetes in humans is uncertain. An optimal method to report inorganic As in humans has not been established. Measurements of As in spot urine are usually adjusted to creatinine (Cr). However, urinary Cr is an independent variable in diabetes. Our aims are to optimize reporting of urinary As in the setting of diabetes and insulin resistance. METHODS: Urinary inorganic As was measured in 24-hour or first-void spot urine from diabetic (n = 31) and non-diabetic (n = 12) subjects and normalized to Cr or specific gravity (SG). The relation of normalized urinary inorganic As to glycemia and surrogate measures of insulin resistance was investigated. Blood pressure, waist circumference, and glycated hemoglobin were also assessed. Homeostasis model assessment was used to determine insulin resistance. RESULTS: A strong correlation was found between spot urinary As adjusted to Cr (R(2) = 0.82) or SG (R(2) = 0.61) to 24-hour urinary As (p &lt; 0.001), while non-adjusted urinary As did not correlate well (R(2) = 0.03, p = 0.46). Adjusting for Cr revealed significant differences in total 24-hour urinary As when comparing diabetic to normal subjects. In contrast, no differences were found when As was adjusted to SG using either 24-hour or spot urine. Moreover, adjusted urinary spot or 24-hour As measures did not correlate with measures of glycemia or insulin resistance. Conclusions: Urinary Cr is an independent variable in diabetes, therefore adjusting spot As for SG is preferred.",
Arsenic,656906,"Dietary administration of sodium arsenite to rats: relations between dose and urinary concentrations of methylated and thio-metabolites and effects on the rat urinary bladder epithelium Abstract: Based on epidemiological data, chronic exposure to high levels of inorganic arsenic in drinking water is carcinogenic to humans, inducing skin, urinary bladder and lung tumors. In vivo, inorganic arsenic is metabolized to organic methylated arsenicals including the highly toxic dimethylarsinous acid (DMA(III)) and monomethylarsonous acid (MMA(III)). Short-term treatment of rats with 100 microg/g trivalent arsenic (As(III)) as sodium arsenite in the diet or in drinking water induced cytotoxicity and necrosis of the urothelial superficial layer, with increased cell proliferation and hyperplasia. The objectives of this study were to determine if these arsenic-induced urothelial effects are dose responsive, the dose of arsenic at which urothelial effects are not detected, and the urinary concentrations of the arsenical metabolites. We treated female F344 rats for 5 weeks with sodium arsenite at dietary doses of 0, 1, 10, 25, 50, and 100 ppm. Cytotoxicity, cell proliferation and hyperplasia of urothelial superficial cells were increased in a dose-responsive manner, with maximum effects found at 50 ppm As(III). There were no effects at 1 ppm As(III). The main urinary arsenical in As(III)-treated rats was the organic arsenical dimethylarsinic acid (DMA(V)). The thio-metabolites dimethylmonothioarsinic acid (DMMTA(V)) and monomethylmonothioarsinic acid (MMMTA(V)) were also found in the urine of As(III)-treated rats. The LC(50) concentrations of DMMTA(V) for rat and human urothelial cells in vitro were similar to trivalent oxygen-containing arsenicals. These data suggest that dietary As(III)-induced urothelial cytotoxicity and proliferation are dose responsive, and the urothelial effects have a threshold corresponding to the urinary excretion of measurable reactive metabolites.",
Arsenic,1373697,"Alteration of adenyl dinucleotide metabolism by environmental stress Abstract: Exposure of cultured mammalian cells to a variety of conditions that induce the synthesis of stress proteins, including hyperthermia, ethanol, cadmium, and arsenite resulted in an increased cellular content of adenyl dinucleotides including diadenosine tetraphosphate (Ap4A). Exposure to other agents that cause metabolic perturbations not known to induce the synthesis of stress proteins, such as cyclohexamide, cytosine arabinoside, hydroxyurea, and ultraviolet irradiation did not alter the content of these nucleotides. It is proposed that these unique nucleotides may mediate adaptive responses of mammalian cells to environmental stress.",
Arsenic,1240438,"Arsenic Mining Waste in the Catchment Area of the Madrid Detrital Aquifer (Spain) Abstract: In recent years, elevated arsenic concentrations in groundwater used for drinking water supplies have been recognised in the Madrid Tertiary detrital aquifer. Although only natural causes have been suggested as the source of arsenic, this study aims to highlight that the anthropogenic contribution cannot be disregarded. During the sub-catchment's areas sampling, we found many geographical sites where natural arsenopyrite [FeAsS] originally encapsulated in pegmatite bodies and quartz veins, was artificially outcropped and dumped out, since mining wastes were scattered and exposed to weathering. Several mineral and ground specimens were collected to analyse its mineralogical and chemical composition by X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) spectrometry and by Environmental Scanning Electron Microscope (ESEM). Both, the abundant existence of secondary phases, such as scorodite [FeAsO sub(4)2H sub(2)O] and jarosite [KFe sub(3)(SO sub(4)) sub( 2)(OH) sub(6)], much more soluble than arsenopyrite, and the lixiviation experiments of arsenopyrite in acidic media to simulate acid mine drainage (AMD) conditions, usually found in old mining districts, point to a potential risk of arsenic contamination of surface water bodies, which operate as recharged waters of the aquifer in the studied area. The elemental determination of heavy metals present in ground samples by XRF analyses, reaching up to 1,173 mg kg super(-1) of copper, 347 mg kg super(-1) of lead and 113,702 mg kg super(-1) of arsenic; and the physicochemical and arsenic fractionation studies of soil samples, led us to classify the soil as Spolic Technosol (Toxic). The contamination of the area due to old mining activities could release arsenic to Madrid water supplies; accordingly, additional decontamination studies should be performed.",
Arsenic,656903,"Inorganic arsenic-induced intramitochondrial granules in mouse urothelium Abstract: Based on epidemiological data, chronic exposure to high levels of inorganic arsenic in the drinking water is carcinogenic to the urinary bladder of humans. Recently, models have been developed involving transplacental administration of inorganic arsenic and subsequent administration of another substance that produces a low incidence of urogenital neoplasms. Administration of arsenite or arsenate in the diet or drinking water to five-to eight-week-old mice or rats rapidly induces urothelial cytotoxicity and regenerative hyperplasia. In mice administered arsenite, we observed eosinophilic intracytoplasmic granules present in the urothelial cells. These granules were not present in urothelial cells of untreated mice or in treated or untreated rats. By transmission electron microscopy, the granules were located within the mitochondrial matrix, that is, mitochondrial inclusions. Arsenic, primarily as arsenite, was present in partially purified mitochondria containing these granules. Cells containing the granules were not usually associated with degenerative changes. Lack of these granules in rats suggests that they are not necessary for inorganic arsenic-induced urothelial cytotoxicity or hyperplasia. These granules have also been observed with exposures to other metals in other tissues and other species, suggesting that they represent a protective mechanism against metal-induced toxicity.",
Arsenic,1021511,"Arsenic contamination in groundwater and its possible sources in Hanam, Vietnam Abstract: This study investigated the arsenic (As) level in groundwater, and the characteristics of aquifer sediment as related to the occurrence of As in groundwater in Hanam, Vietnam. The deposition and transport of As-containing substances through rivers were also examined. Arsenic concentrations in 88% of the groundwater samples exceeded the As limit for drinking water based on the WHO standards. The dominating form of arsenic was As(III). The maximum total As content in bore core sediment was found in a peat horizon of the profiles and generally, elevated levels of As were also found in other organic matter-rich horizons. Total As contents of the bore core sediments were significantly correlated with crystalline iron oxide, silt and clay contents, suggesting that As in aquifer sediment was mainly associated with iron (hydr)oxides and clay mineral. In the groundwater, As concentration showed significant correlations with the total concentrations of Fe and HCO (3) (-) . Significant correlations between HCl-extractable As and non-crystalline Fe oxide, total C, N, and S were also observed in the profiles. The results support the hypothesis that under favorable reductive conditions established by the degradation of organic matter, the dissolution of iron (hydr)oxides releases adsorbed As into the groundwater. The deposition of As in the sediments from the Red River were significantly higher than that in the Chau Giang River, suggesting that the Red River is the main source of As-containing substances deposited in the study area.",
Arsenic,2149271,"Geochemical and mineralogical characterization of a neutral, low-sulfide/high-carbonate tailings impoundment, Markusovce, eastern Slovakia Abstract: ",
Arsenic,598617,"Effects of subchronic coexposure to arsenic and endosulfan on the erythrocytes of broiler chickens: A biochemical study Abstract: Arsenic is a known global groundwater contaminant. The organochlorine insecticide endosulfan has gained significance as an environmental pollutant due to its widespread use in the control of many food- and non-food-crop-damaging insects. The adverse effects produced by arsenic or endosulfan alone in humans and animals are well documented, but very little is known about the consequences of their coexposure. We evaluated whether their simultaneous exposure can induce oxidative stress and affect antioxidative systems and certain membrane-bound enzymes in erythrocytes of broiler chickens. Day-old chicks were exposed to 3.7 ppm of arsenic via drinking water or 30 ppm of endosulfan-mixed feed or similarly coexposed to these in the same dose levels for 60 days. At term, the impact of their coexposure was assessed by evaluating lipid peroxidation (LPO), activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione-S-transferase (GST), different ATPases and acetylcholinesterase (AChE) in erythrocytes, serum glucose, and levels of glutathione (GSH) and glycosylated hemoglobin (GHb) in blood. LPO was increased with all of the treatments. Catalase was decreased with endosulfan and the coexposure, but not with arsenic, whereas GSH was decreased with arsenic and endosulfan, but not with the coexposure. All of the treatments increased SOD and GPx activities. GST activity was increased only in the coexposed birds. None of the treatments affected the activities of total ATPase and Mg2+-ATPase. Na+-K+-ATPase activity was decreased in the endosulfan-treated and the coexposed birds. All three exposures increased erythrocyte AChE activity. Endosulfan increased the serum glucose level and arsenic and endosulfan increased GHb levels, but these were not altered in the coexposed birds. Erythrocyte protein content was insignificantly decreased with these treatments. Overall, the effects of coexposure were not appreciably different from either of the agents, except on AChE, GSH, and glucose. The results do not reflect any specific type of interaction between these agents in chicken erythrocytes, but they do indicate that the coexposure induces a low level of oxidative stress, which is comparable to that induced by arsenic or endosulfan.",
Arsenic,1345484,Evaluation of arsenic and selenium in Brazilian soluble coffee by inductively coupled plasma atomic emission spectrometry with hydride generation Abstract: ,
Arsenic,1344414,"Modeling and surface observations of arsenic dispersion from a large Cu-smelter in southwestern Europe Abstract: Arsenic is a toxic element for human health. Consequently, a mean annual target level for arsenic at 6 ng m(-3) in PM10 was established by the European Directive 2004/107/CE to take effect January 2013. Cu-smelters can contribute to one-third of total emissions of arsenic in the atmosphere. Surface observations taken near a large Cu-smelter in the city of Huelva (Spain) show hourly arsenic concentrations in the range of 0-20 ng m(-3). The arsenic peaks of 20 ng m(-3) are higher than values normally observed in urban areas around Europe by a factor of 10. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model has been employed to predict arsenic emissions, transport, and dispersion from the Cu-smelter. The model utilized outputs from different meteorological models and variations in the model physics options to simulate the uncertainty in the dispersion of the arsenic plume. Modeling outputs from the physics ensemble for each meteorological model driving HYSPLIT show the same number of arsenic peaks. HYSPLIT coupled with the Weather Research and Forecasting (WRF-ARW) meteorological output predicted the right number of peaks for arsenic concentration at the observation site. The best results were obtained when the WRF simulation used both four-dimensional data assimilation and surface analysis nudging. The prediction was good in local sea breeze circulations or when the flow was dominated by the synoptic scale prevailing winds. However, the predicted peak was delayed when the transport and dispersion was under the influence of an Atlantic cyclone. The calculated concentration map suggests that the plume from the Cu-smelter can cause arsenic pollution events in the city of Huelva as well as other cities and tourist areas in southwestern Spain.",
Arsenic,2345617,"Folk pharmaceutical formulations in western Mediterranean: Identification and safety of clays used in pelotherapy Abstract: <strong>ETHNOPHARMACOLOGICAL RELEVANCE: </strong>Clays are naturally occurring ingredients of many natural health products, being included in most of ancient Mediterranean/European medical texts and currently used to prepare therapeutic hot-muds (peloids) in several thermal stations of the Mediterranean region. Clays are included in the formulation of peloids as vehicles of the mineral-medicinal water, to obtain inorganic gels with rheological and thermal properties suitable to be topically applied. Knowledge about formulations and preparation procedures of these traditional medicines has been orally transmitted since ancient times. Increasing recognition of the therapeutic utility of these traditional and natural health care substances make necessary a full ethnopharmaceutic research to ascertain those compositional characters that allow to establish quality attributes and corresponding requirements for these materials and products, including identity, purity, richness and safety.<br /><br /><strong>MATERIALS AND METHODS: </strong>Five clay samples (A, B, C, D and E) currently used in various spa centers of southern European/Mediterranean countries were studied. X-Ray diffraction (XRD) and X-ray fluorescence (XRF) data were used to asses sample identity and richness. Elemental impurities and microbiological contaminants were also determined and compared to normative limits. Particle size distribution was related to their safety as powder materials.<br /><br /><strong>RESULTS: </strong>Samples A, C, D and E were identified as &quot;high purity clay&quot;, while sample B was identified as a mix of clay minerals and carbonates. The presence of carbonates in this sample could compromise its suitability for pelotherapy. The studied clays meet the main normative limits for metals impurities, with the exception of arsenic in sample A and nickel in sample B. The samples comply with the microbiological limits proposed by European legislation for medicinal products. According to the particle size of the studied samples, prevention and control of dust exposure must be considered.<br /><br /><strong>CONCLUSIONS: </strong>Despite their demonstrated longevity, the use of clays in traditional medicine formulations as peloids greatly requires comprehension of their identity and safety attributes. Continuity of these mineral substances as recognized health care ingredients oblige to conduct interdisciplinary research to know the features that sustain their traditional use in the preparation of medicines (ethnopharmaceutics).",
Arsenic,551333,"Chronic low-level arsenic exposure causes gender-specific alterations in locomotor activity, dopaminergic systems, and thioredoxin expression in mice Abstract: Arsenic (As) is a toxic metalloid widely present in the environment. Human exposure to As has been associated with the development of skin and internal organ cancers and cardiovascular disorders, among other diseases. A few studies report decreases in intelligence quotient (IQ), and sensory and motor alterations after chronic As exposure in humans. On the other hand, studies of rodents exposed to high doses of As have found alterations in locomotor activity, brain neurochemistry, behavioral tasks, and oxidative stress. In the present study both male and female C57Bl/6J mice were exposed to environmentally relevant doses of As such as 0.05, 0.5, 5.0, or 50 mg As/L of drinking water for 4 months, and locomotor activity was assessed every month. Male mice presented hyperactivity in the group exposed to 0.5 mg As/L and hypoactivity in the group exposed to 50 mg As/L after 4 months of As exposure, whereas female mice exposed to 0.05, 0.5, and 5.0 mg As/L exhibited hyperactivity in every monthly test during As exposure. Furthermore, striatal and hypothalamic dopamine content was decreased only in female mice. Also decreases in tyrosine hydroxylase (TH) and cytosolic thioredoxin (Trx-1) mRNA expression in striatum and nucleus accumbens were observed in male and female mice, respectively. These results indicate that chronic As exposure leads to gender-dependent alterations in dopaminergic markers and spontaneous locomotor activity, and down-regulation of the antioxidant capacity of the brain.",
Arsenic,1508596,"Effect of dietary treatment with dimethylarsinous acid (DMA(III)) on the urinary bladder epithelium of arsenic (+3 oxidation state) methyltransferase (As3mt) knockout and C57BL/6 wild type female mice Abstract: Chronic exposure to inorganic arsenic (iAs) is carcinogenic to the human urinary bladder. It produces urothelial cytotoxicity and proliferation in rats and mice. DMA, a major methylated urinary metabolite of iAs, is a rat bladder carcinogen, but without effects on the mouse urothelium. DMA was shown to be the likely urinary metabolite of DMA inducing urothelial changes and is also postulated to be one of the active metabolites of iAs. To evaluate potential DMA-induced urothelial effects, it was administered to As3mt knockout mice which cannot methylate arsenicals. Female C57BL/6 wild type and As3mt knockout mice (10/group) were administered DMA, 77.3ppm in water for four weeks. Urothelial effects were evaluated by light and scanning electron microscopy (EM) and immunohistochemical detection of bromodeoxyuridine (BrdU) incorporation. EM findings were rated 1-5, with higher rating indicating greater extent of cytotoxicity visualized. DMA significantly increased the BrdU labeling index, a ratio of BrdU labeled cells to non-labeled cells, in the treated knockout group compared to control and wild type treated groups. DMA induced simple hyperplasia in more knockout mice (4/10) compared to wild type mice (2/10). All treated knockout mice had more and larger intracytoplasmic granules compared to the treated wild type mice. Changes in EM classification were not significant. In conclusion, DMA induces urothelial toxicity and regenerative hyperplasia in mice and most likely plays a role in inorganic arsenic-induced urothelial changes. However, DMA does not induce hyperplasia in mice, suggesting that urinary concentrations of DMA do not reach cytotoxic levels in DMA-treated mice.",
Arsenic,1519021,"Arsenate accumulation and arsenate-induced glutathione export in astrocyte-rich primary cultures Abstract: Arsenate is a toxic compound that has been connected with neuropathies and impaired cognitive functions. To test whether arsenate affects the viability and the GSH metabolism of brain astrocytes, we have used primary astrocyte cultures as model system. Incubation of astrocytes for 2 h with arsenate in concentrations of up to 10 mM caused an almost linear increase in the cellular arsenic content, but did not acutely compromise cell viability. The presence of moderate concentrations of arsenate caused a time- and concentration-dependent loss of GSH from viable astrocytes which was accompanied by a matching increase in the extracellular GSH content. Half-maximal effects were observed for arsenate in a concentration of about 0.3 mM. The arsenate-induced stimulated GSH export from astrocytes was prevented by MK571, an inhibitor of the multidrug resistance protein 1. Exposure of astrocytes to arsenite increased the specific cellular arsenic content and stimulated GSH export to values that were similar to those observed for arsenate-treated cells, while dimethylarsinic acid was less efficiently accumulated by the cells and did not modulate cellular and extracellular GSH levels. The observed strong stimulation of GSH export from astrocytes by arsenate suggests that disturbances of the astrocytic GSH metabolism may contribute to the observed arsenic-induced neurotoxicity.",
Arsenic,628688,"Mortality for certain diseases in areas with high levels of arsenic in drinking water Abstract: Blackfoot disease was prevalent in a limited area on the southwest coast of Taiwan, where artesian well water containing arsenic (median = 0.78 ppm arsenic) had been used for many years. Previous studies of arsenic exposure in the blackfoot disease endemic area have been focused on malignant tumors. We, therefore, conducted this study to analyze mortality of all death causes in blackfoot disease endemic areas and to determine other neglected cancers or noncancer diseases related to artesian well water containing high levels of arsenic. We calculated standardized mortality ratios for cancer and noncancer diseases, by sex, during the period from 1971 to 1994 and compared them to the local reference group (i.e, Chiayi-Tainan County) and the national reference group (i.e., Taiwan population). The results revealed marked standardized mortality ratio differences for the 2 reference groups. Greater mortality was found for males and females with bladder, kidney, skin, lung, nasal-cavity, bone, liver, larynx, colon, and stomach cancers, as well as lymphoma than in the local reference population. With respect to noncancer diseases, we found greater mortality for males and females who had vascular disease, ischemic heart disease, diabetes mellitus, and bronchitis than in the local reference group. Mortalities for other diseases–including rectal cancer, cerebrovascular disease, and other diseases–were higher among cases than the local reference group. Our results indicated that the hazardous effect of arsenic is systemic. Diseases related to arsenic exposure included those reported previously by other investigators, as well as diseases reported in the present study.",
Arsenic,1351992,"The effects of sulfur, thiol, and thiol inhibitor compounds on arsine-induced toxicity in the human erythrocyte membrane Abstract: The mechanism of arsine (AsH(3)) toxicity is not completely understood. The first cytotoxic effect of AsH(3) is disruption of ion homeostasis, with a subsequent hemolytic action. The only accepted treatment for AsH(3) toxicity is exchange transfusion of the blood. In this study the effect of sulfur, sulfur compounds, thiol-containing compounds, and thiol inhibitors on AsH(3)-induced disruption of membrane transport and hemolysis in human erythrocytes was investigated in vitro. Elemental sulfur, sodium thiosulfate, 5, 5'-dithio-bis(2-nitrobenzoic acid), and meso-2,3-dimercaptosuccinic acid were successful in delaying hemolysis, but the most successful agent was the sulfhydryl inhibitor, N-ethylmaleimide (NEM). This indicated that sulfhydryl groups, possibly membrane sulfhydryls, are major factors in the hemolytic mechanism of AsH(3). Measuring intracellular ion concentrations tested the effect of NEM on AsH(3)-induced disruption of membrane transport. AsH(3) alone caused all ions tested to flow with their concentration gradients: Intracellular K+ and Mg++ decreased, whereas Na+, Cl-, and Ca++ increased. NEM was unable to prevent ion loss except for Ca++, whose increase was prevented for 1 h after AsH(3) treatment. The influx of Ca++ in AsH(3)-treated erythrocytes is an irreversible event leading to hemolysis. Reduction of oxygenated hemoglobin to carboxyhemoglobin completely inhibited AsH(3)-induced hemolysis. In addition, AsH(3) and NEM had no direct chemical interactions. We concluded that membrane sulfhydryl groups are likely targets of AsH(3) toxicity, with NEM being able to prevent AsH(3)-induced hemolysis.",
Arsenic,515890,"Arsenic exposure and cognitive performance in Mexican schoolchildren Abstract: BACKGROUND: Previous studies have suggested an effect of high arsenic concentration on cognitive and neurobehavioral function in humans. OBJECTIVE: Our goal was to identify demographic and nutritional factors that are associated with As exposure and the influence of this exposure on cognitive function in school-age children. METHODS: We recruited 602 children 6-8 years of age living within 3.5 km of a metallurgic smelter complex in the city of Torreon, Mexico, to participate in a cross-sectional evaluation. Of these, 591 had complete anthropometry, iron, and zinc status by biochemical measurements in serum, blood lead concentration (PbB), and arsenic in urine (UAs), and 557 completed several cognitive performance tests. RESULTS: The mean for UAs was 58.1 +/- 33.2 mu g/L; 52% of the children had UAs concentrations < 50 mu g/L, and 50.7% of children had PbB >= 10 mu g/dL. UAs concentration was associated with low socioeconomic status. Nutritional status indicators were not related to UAs concentrations. Linear and logistic regressions adjusted for hemoglobin concentration, PbB, and sociodemographic confounders showed a significant inverse association between UAs and Visual-Spatial Abilities with Figure Design, the Peabody Picture Vocabulary Test, the WISC-RM Digit Span subscale, Visual Search, and Letter Sequencing Tests (p < 0.05). Boys excreted significantly more UAs (p < 0.05) and were affected on different cognitive areas than girls. CONCLUSIONS: Children living in an area contaminated with both As and lead showed that As contamination can affect children's cognitive development, independent of any effect of lead.",
Arsenic,734919,"Age and exposure to arsenic alter base excision repair transcript levels in mice Abstract: Arsenic (As) induces DNA-damaging reactive oxygen species. Most oxidative DNA damage is countered by base excision repair (BER), the capacity for which may be reduced in older animals. We examined whether age and consumption of As in lactational milk or drinking water influences BER gene transcript levels in mice. Lactating mothers and 24-week-old mice were exposed (24 h or 2 weeks) to As (2 or 50 p.p.m.) in drinking water. Lung tissue was harvested from adults, neonates (initially 1 week old) feeding from lactating mothers and untreated animals 1-26 weeks old. Transcripts encoding BER proteins were quantified. BER transcript levels decreased precipitously with age in untreated mice but increased in neonates whose mothers were exposed to 50 p.p.m. As for 24 h or 2 weeks. Treatment of 24-week-old mice with 2 or 50 p.p.m. As for 2 weeks decreased all transcript levels measured. Exposure to As attenuated the age-related transcript level decline for only one BER gene. We conclude that aging is associated with a rapid reduction of BER transcript levels in mice, which may contribute to decreased BER activity in older animals. Levels of As that can alter gene expression are transmitted to neonatal mice in lactational milk produced by mothers drinking water containing As, raising concerns about breastfeeding in countries having As-contaminated groundwater. Reduction of BER transcript levels in 24-week-old mice exposed to As for 2 weeks suggests As may potentiate sensitivity to itself in older animals.",
Arsenic,1797811,"A molecular study on bacterial resistance to arsenic-toxicity in surface and underground waters of Latium (Italy) Abstract: Latium, a region in central Italy, is known for its extensive volcanic areas that make a significant contribution to the arsenic (As) contamination of freshwater environments, even though some degree of As water pollution may be caused by human activities. The information available on indigenous As-resistant prokaryotes in aquatic environments of Latium is, however, still limited. In this study, we describe new bacteria that are resistant to arsenic toxicity and were isolated from the surface waters of Lake Vico and the Sacco River, two groundwater systems in Latium, as well as from bottled natural mineral water from the same region. The 16S rRNA gene sequence analysis for the As-resistant strains in lake and river waters points to a prevalence of ?- and ?-Proteobacteria, while ?-Proteobacteria, Firmicutes and Bacteroidetes are represented to a lesser extent. By contrast, solely ?-Proteobacteria were isolated from groundwater samples. The presence of Actinobacteria was documented exclusively in bottled mineral water. In addition, we conducted a DNA sequence-based study on the gene codifying arsB, an As(III) efflux membrane protein pump related to arsenic resistance, for all the As-resistant bacterial isolates. A phylogenetic analysis was carried out on the newly sequenced 16S rRNA genes and arsB in the present study as well as on an additional 16S rRNA/arsB dataset we obtained previously from Lake Albano, from the Tiber and from a well in Bassano Romano located in Latium (Davolos and Pietrangeli, 2011). Overall, the phylogenetic diversity of As-resistant bacteria in underground water was very limited if compared with lentic and lotic waters. Lastly, our molecular data support the hypothesis that the horizontal gene transfer of ars in As-containing freshwater environments is not limited to closely-related genomes, but also occurs between bacteria that are distant from an evolutionary viewpoint, thereby indicating that such genetic events may be considered a source of microbial resistance to arsenic-toxicity.",
Arsenic,2278537,"Characterization of tephras dispersed by the recent eruptions of volcanoes Calbuco (1961), Chaitén (2008) and Cordón Caulle Complex (1960 and 2011), in Northern Patagonia Abstract: Pyroclastic materials dispersed in recent volcanic eruptions in Northern Patagonia were analysed in order to characterize the volcanic provenance by the geochemical fingerprint. The volcanic products studied were dispersed by eruptions of volcanoes Calbuco in 1961, Chaitén in 2008, and Cordón Caulle Volcanic Complex (CCVC) in 1960 and 2011. The geochemical characterization was based on the determination of 35 major and trace elements by Instrumental Neutron Activation Analysis, including geochemical tracer such as Rare Earth Elements (REE). The study of the pyroclastic products also included the morphological analysis by petrographic and scanning electron microscopy, and the mineralogical characterization by X-ray diffraction. Geochemical tracers determined in the glass fraction of the dispersed pyroclastic materials allowed a clear discrimination of the three volcanoes that gave origin to the tephras, the three of them with different evolution degree. Tephras from 1960 and 2011 CCVC eruptions showed the same geochemical signature. The geochemical parameters providing the differential characterization are the normalized REE and multi-element patterns, the Eu anomaly, the heavy to light and medium to light REE normalized ratios, and the Cs, Sc, Rb, Ta and Th concentrations. The bulk glassy fraction showed the same composition for each volcanic eruption in samples collected even in distant sites (from 100 to 220 km in Chaitén, 2008, and from 80 to 650 km in CCVC 2011), attesting to be the most reliable material for correlation purposes. According to the mineralogy, cristobalite was found in volcano Chaitén tephra as an indicator of such origin. Arsenic, an element of environmental interest, exhibited concentrations ranging from 6 to 16 ?g g?1, with the highest values corresponding to Puyehue–Cordón Caulle and Chaitén products.",
Arsenic,1070496,"Metabolic adaptations to arsenic-induced oxidative stress in male wistar rats Abstract: The present study was planned to investigate the effect of arsenic in rats on several biochemical indices of oxidative stress. Rats were exposed to arsenite in drinking water for upto 12 weeks. Chronic exposure to arsenic for a period of 12 weeks significantly (p &lt; 0.05) increased arsenic burden in blood, liver, and kidney. Several intrinsic antioxidant defenses were activated after a 4-week exposure to arsenic. Some remained elevated, but others became depressed over a longer exposure period. Alterations in most of the biochemical variables reached statistical significant (p &lt; 0.05). Arsenic significantly (p &lt; 0.01) reduced mRNA expression of the superoxide dismutase 2 (SOD2) gene with respect to the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene. These observations indicated that prolong exposure to arsenic causes induction of oxidative stress and biochemical alterations.",
Arsenic,1338609,"Deficiency in the nuclear factor E2-related factor 2 renders pancreatic ?-cells vulnerable to arsenic-induced cell damage Abstract: Chronic human exposure to inorganic arsenic (iAs), a potent environmental oxidative stressor, is associated with increased prevalence of type 2 diabetes, where impairment of pancreatic ?-cell function is a key pathogenic factor. Nuclear factor E2-related factor 2 (Nrf2) is a central transcription factor regulating cellular adaptive response to oxidative stress. However, persistent activation of Nrf2 in response to chronic oxidative stress, including inorganic arsenite (iAs³?) exposure, blunts glucose-triggered reactive oxygen species (ROS) signaling and impairs glucose-stimulated insulin secretion (GSIS). In the current study, we found that MIN6 pancreatic ?-cells with stable knockdown of Nrf2 (Nrf2-KD) by lentiviral shRNA and pancreatic islets isolated from Nrf2-knockout (Nrf2?/?) mice exhibited reduced expression of several antioxidant and detoxification enzymes in response to acute iAs³? exposure. As a result, Nrf2-KD MIN6 cells and Nrf2?/? islets were more susceptible to iAs³? and monomethylarsonous acid (MMA³?)-induced cell damage, as measured by decreased cell viability, augmented apoptosis and morphological change. Pretreatment of MIN6 cells with Nrf2 activator tert-butylhydroquinone protected the cells from iAs³?-induced cell damage in an Nrf2-dependent fashion. In contrast, antioxidant N-acetyl cysteine protected Nrf2-KD MIN6 cells against acute cytotoxicity of iAs³?. The present study demonstrates that Nrf2-mediated antioxidant response is critical in the pancreatic ?-cell defense mechanism against acute cytotoxicity by arsenic. The findings here, combined with our previous results on the inhibitory effect of antioxidants on ROS signaling and GSIS, suggest that Nrf2 plays paradoxical roles in pancreatic ?-cell dysfunction induced by environmental arsenic exposure.",
Arsenic,1371391,URINARY ARSENIC SPECIATION AND THE ASSESSMENT OF UK DIETARY ENVIRONMENTAL AND OCCUPATIONAL EXPOSURES TO ARSENIC Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM HUMAN METABOLISM TOXICOLOGY,
Arsenic,1794766,"Application of advanced oxidation processes for cleaning of industrial water generated in wet dedusting of shaft furnace gases Abstract: The paper presents results of studies into advanced oxidation processes in 03 and 03/UV systems. An advanced oxidation process (AOP) was conducted to reduce the load of impurities in circulating waters from wet de-dusting of shaft furnace gases. Besides inorganic impurities, i.e. mainly arsenic compounds (16 g As L(-1) on average), lead, zinc, chlorides and sulphates, the waters also contain some organic material. The organic material is composed of a complex mixture that contains, amongst others, aliphatic compounds, phenol and its derivatives, pyridine bases, including pyridine, and its derivatives. The test results show degradation of organic and inorganic compounds during ozonation and photo-oxidation processes. Analysis of the solutions from the processes demonstrated that the complex organic material in the industrial water was oxidized in ozonation and in photo-oxidation, which resulted in formation of aldehydes and carboxylic acids. Kinetic degradation of selected pollutants is presented. Obtained results indicated that the O3/UV process is more effective in degradation of organic matter than ozonation. Depending on the process type, precipitation of the solid phase was observed. The efficiency of solid-phase formation was higher in photo-oxidation with ozone. It was found that the precipitated solid phase is composed mainly of arsenic, iron and oxygen.",
Arsenic,1597314,"Effect of pH and stream order on iron and arsenic speciation in boreal catchments Abstract: Riverine transport of iron (Fe) and arsenic (As) is affected by their associations with natural organic matter (NOM) and suspended iron (oxy)hydroxides. Speciation has a strong influence on element transport from the headwaters to the ocean because NOM may be transported over longer distances compared to iron (oxy)hydroxides. We show that Fe speciation changes along the flow path of a boreal watercourse, as water moves from NOM-rich, acidic first-order streams with pH as low as 3.9 to less acidic higher-order systems (up to pH 6.4). Analysis by Flow Field-Flow Fractionation and chemical equilibrium modelling revealed that Fe from wetland-dominated headwaters was mainly exported as Fe-NOM complexes; in catchments with a stream order &gt;1 and with higher pH, Fe was present in Fe-NOM complexes and precipitated as nanoparticulate iron(oxy)hydroxides which aggregated as the pH increased, with their size eventually exceeding the membrane filters cut-off (0.2 µm). The measured NOM-bound Fe decreased with increasing pH, from 0.38 to 0.16 mmol Fe?gNOM-1. The high concentrations of NOM-bound Fe emphasize the importance of boreal catchments to Fe export to the oceans. Concentrations of As in the &lt;0.2 µm fraction but larger than what is usually considered &quot;truly dissolved&quot; (&lt;1000 g?mol-1), decreased from 75% to 26% with increasing pH. The As in this size range was mainly associated with NOM but at pH &gt;4.5 became associated with iron(oxy)hydroxides, and its transport thus became more coupled to that of the iron(oxy)hydroxides downstream in the circumneutral streams.",
Arsenic,1340006,"Hematological effects of arsenic in rats after subchronical exposure during pregnancy and lactation: The protective role of antioxidants Abstract: Free radicals production is involved in the toxicity of arsenic. The aim of this study was to determine whether biochemical changes occurred in the blood of arsenic-exposed pups during gestation and lactation, and additionally to investigate the potential beneficial role of the administration of certain antioxidants against arsenic exposure damage. Pregnant wistar rats received the following treatments as drinking water: (1) distilled water; (2) arsenic (50mg/L); (3) antioxidants: zinc (20mg/L)+vitamin C (2g/L)+vitamin E (500mg/L); (4) arsenic (50mg/L)+antioxidants: zinc (20mg/L)+vitamin C (2g/L)+vitamin E (500mg/L). We found a normocytic and normochromic anemia as well as a significant increase in hemolysis, TBARS production and catalase activity in the blood of arsenic intoxicated pups. Moreover, this metalloid produced a significant increase of serum cholesterol, triglicerids and urea levels whereas the proteins diminished. These effects were palliated in some extent by the coadministration of vitamins and zinc. Our findings suggest that administration of antioxidants during gestation and lactation could prevent some of the negative effects of arsenic.",
Arsenic,1373284,"Spectrophotometric determination of arsenic. Part II Abstract: IPA COPYRIGHT: ASHP A spectrophotometric method for the determination of microquantities of arsenic in organic material is described. The arsenic is determined after the decomposition of the organic material and its transformation into arsine. Two procedures for this determination were worked out. In the first procedure the arsenic is determined measuring the quantity in the reaction of nonreacting part of the potassium ferricyanide. This is made by reading the absorbance of the reagent blank at 420 nm. against the sample. In the second procedure, the arsenic is determined by measuring the ferrocyanide quantity produced by the reduction. The ferrocyanide is determined as a ferrophenanthroline complex by measuring the absorbance at 510 nm. against the reagent blank. The first procedure is simpler, while the second procedure is more sensitive and more suitable for the determination of arsenic quantities smaller than 5 mcg. in 10 ml. of the reaction mixture. The value of the method has been verified by a recovery test and by the comparison of the results obtained by the molybdenum blue method. The method is reproducible, accurate and economical and can be recommended for the determination of arsenic in organic material.",
Arsenic,1250975,"Arsenic tolerance in a Chlamydomonas photosynthetic mutant is due to reduced arsenic uptake even in light conditions Abstract: Arsenate resistance has been used for screening for photosynthetic mutants of Chlamydomonas, since photosynthetic mutants, such as CC981 defective in phosphoribulokinase, were shown to have arsenate resistance. Also, another type of arsenate-resistant mutants, including AR3 that lacks a homolog of a phosphate (Pi) transporter, PTB1, has been isolated. We investigated the uptake of Pi and arsenate, and the gene expression of Pi transporters, which are involved in both Pi and arsenate transport, in mutants CC981 and AR3. In the wild type, both Pi and arsenate uptake were initially high, but were inactivated in the presence of arsenate with time, especially in the dark. In contrast, both mutants were shown to exhibit higher Pi uptake, but lower arsenate uptake than the wild type, regardless of the presence or absence of light. Then, the gene expression of Pi transporters in the cells used for the uptake measurements was investigated and compared between the mutants and the wild type. In CC981, the mRNA levels of PTA2 and PTA4 were higher, while those of PTB3 and PTB5 were lower, as compared with in the wild type. In AR3, those of PTA2 and PTB2 were higher, but that of PTB5 was lower than in the wild type. These findings suggest that the arsenate resistance shown by the mutants in light is due to reduction of arsenate uptake probably through the down-regulation of some Pi transporter expression, while the Pi uptake maintained even in the dark is possibly related to higher expression of other Pi transporter(s) than in the wild type.",
Arsenic,2088302,"Comparison of mineral-based amendments for ex-situ stabilization of trace elements (As, Cd, Cu, Mo, Ni, Zn) in marine dredged sediments: a pilot-scale experiment Abstract: Trace element pollution of marine dredged sediments is an emerging problem all over the world. Comparing to other wastes, trace elements stabilization is more difficult both due to the wide range of contaminants present in the marine sediments and their inherent physicochemical properties. In this study, a pilot-scale experiment was performed to stabilize As, Cd, Cu, Mo, Ni, and Zn in a multi-contaminated sediment sample using hematite, zero-valent iron and zeolite. Results showed that iron-based amendments were able to reduce the leaching and the bioavailability of trace elements in the sediment sample, while zeolite was unsuitable. Chemical stabilization through iron-based amendments seems to be a promising approach as a low-cost alternative to traditional stabilization methods involving chemical reagents.",
Arsenic,1359127,CYTOLOGICAL CHANGES IN THE FISH LEPOMIS-CYANELLUS LIVER FOLLOWING CHRONIC ENVIRONMENTAL ARSENIC EXPOSURE Abstract: HEEP COPYRIGHT: BIOL ABS.,
Arsenic,1337710,"Arsenite tolerance in rice (Oryza sativa L.) involves coordinated role of metabolic pathways of thiols and amino acids Abstract: Thiolic ligands and several amino acids (AAs) are known to build up in plants against heavy metal stress. In the present study, alteration of various AAs in rice and its synchronized role with thiolic ligand was explored for arsenic (As) tolerance and detoxification. To understand the mechanism of As tolerance and stress response, rice seedlings of one tolerant (Triguna) and one sensitive (IET-4786) cultivar were exposed to arsenite (0-25 ?M) for 7 days for various biochemical analyses using spectrophotometer, HPLC and ICPMS. Tolerant and sensitive cultivars respond differentially in terms of thiol metabolism, essential amino acids (EEAs) and nonessential amino acids (NEEAs) vis-á-vis As accumulation. Thiol biosynthesis-related enzymes were positively correlated to As accumulation in Triguna. Conversely, these enzymes, cysteine content and GSH/GSSG ratio declined significantly in IET-4786 upon As exposure. The level of identified phytochelatin (PC) species (PC(2), PC(3) and PC(4)) and phytochelatin synthase activity were also more pronounced in Triguna than IET-4786. Nearly all EAAs were negatively affected by As-induced oxidative stress (except phenylalanine in Triguna), but more significantly in IET-4786 than Triguna. However, most of the stress-responsive NEAAs like glutamic acid, histidine, alanine, glycine, tyrosine, cysteine and proline were enhanced more prominently in Triguna than IET-4786 upon As exposure. The study suggests that IET-4786 appears sensitive to As due to reduction of AAs and thiol metabolic pathway. However, a coordinated response of thiolic ligands and stress-responsive AAs seems to play role for As tolerance in Triguna to achieve the effective complexation of As by PCs.",
Arsenic,1025214,"Interplay between cellular methyl metabolism and adaptive efflux during oncogenic transformation from chronic arsenic exposure in human cells Abstract: After protracted low level arsenic exposure, the normal human prostate epithelial cell line RWPE-1 acquires a malignant phenotype with DNA hypomethylation, indicative of disrupted methyl metabolism, and shows arsenic adaptation involving glutathione overproduction and enhanced arsenic efflux. Thus, the interplay between methyl and glutathione metabolism during this progressive arsenic adaptation was studied. Arsenic-treated cells showed a time-dependent increase in LC50 and a marked increase in homocysteine (Hcy) levels. A marked suppression of S-adenosylmethionine (SAM) levels occurred with decreased methionine adenosyltransferase 2A (converts methionine to SAM) expression and increased negative regulator methionine adenosyltransferase B, suggesting reduced conversion of Hcy to SAM. Consistent with Hcy overproduction, activity and expression of S-adenosylhomocysteine hydrolase (converts S-adenosylhomocysteine to Hcy) were both increased. Expression of cystathionine beta-synthase, a key gene in the transsulfuration pathway, and various glutathione production genes were increased, resulting in a 5-fold increase in glutathione. Arsenic efflux increased along with expression of ATP-binding cassette protein C1, which effluxes arsenic as a glutathione conjugate. Evidence of genomic DNA hypomethylation was observed during early arsenic exposure, indicating that the disruption in methyl metabolism had a potential impact related to oncogenesis. Thus, cellular arsenic adaptation is a dynamic, progressive process that involves decreased SAM recycling and concurrent accumulation of Hcy, which is channeled via transsulfuration to increase glutathione and enhance arsenic efflux but may also impact the carcinogenic process.",
Arsenic,1597420,"Treatment of Arsenic-, Chromium-, Copper- and Pentachlorophenol-Polluted Soil Using Flotation Abstract: ",
Arsenic,1391117,"Role Of Oxidative Stress In The Modulation Of Ahr-Regulated Gene Expression By Heavy Metals Abstract: Since heavy metals, mainly arsenite (As3+), cadmium (Cd2+) and chromium (Cr6+), have been shown to exert their toxicity, at least partly, by the generation of reactive oxygen species (ROS), we evaluated the role of metal-induced ROS on the expression of AHR-regulated genes: Cyp1a1, NAD(P)H:quinone oxidoreductase (QOR), and glutathione S-transferase Ya (GST Ya). For this purpose, Hepa 1c1c7 cells were treated with 5 ?M of As3+, Cd2+ or Cr6+ in the presence or absence of TCDD (1 nM), an AHR ligand. All three metals caused perturbations in cellular glutathione redox status, but only Cd2+ and Cr6+ increased the production of ROS. Although all three metals potentiated the induction of Cyp1a1 mRNA by TCDD, they decreased the stability of the induced protein and inhibited the induction of its activity. Pre-treatment with the thiol antioxidant N-acetylcysteine (NAC) did not alter Cyp1a1 mRNA levels but completely abrogated the inhibition of Cyp1a1 activity induction by all three metals. In parallel, Cyp1a1 mRNA expression was further potentiated whereas Cyp1a1 activity was further inhibited when cells were pretreated with the glutathione synthase inhibitor, L-buthionine-[S, R]-sulfoximine (BSO). Furthermore, all three metals induced the expression of heme oxygenase-1 (HO-1) which was further potentiated with BSO but inhibited with NAC pretreatments. Additionally, metals alone induced Cyp1a1 mRNA expression, which was superinduced in the presence of the protein synthesis inhibitor, cycloheximide. All three metals, alone or in the presence of TCDD, enhanced QOR and GST Ya activities and mRNA levels, an effect that was completely abrogated with NAC pretreatment and markedly potentiated with BSO. Pre-treatment with the DNA transcription suppressor, actinomycin-D, abolished the induction of QOR and GST Ya mRNA levels by the three metals. Our data clearly show that As3+, Cd2+, and Cr6+ induced ROS production modulates Cyp1a1 activity by decreasing Cyp1a1 protein stability and inducing HO-1, but induces QOR and GST Ya activities at the transcriptional level, likely regulated by the antioxidant response element.",
Arsenic,1579408,"Use of peat-based sorbents for removal of arsenic compounds Abstract: It is important to apply sorbent materials for purification of water from arsenic contamination due to serious arsenic pollution worldwide. We have developed new sorbents based on natural materials that provide a cheap and environmentally friendly alternative. For the first time, peat modified with iron compounds and iron humates were tested for sorption of arsenic compounds. The highest sorption capacity was found in peat modified with iron compounds. We have found that sorption of different arsenic speciation forms was strongly dependent on solution pH, reaction time and temperature. Calculations of the sorption process using thermodynamic parameters indicate the spontaneity of sorption process and its endothermic nature. Sorption kinetics showed that most arsenates are removed within 2 hours, and the kinetics of arsenate sorption on modified peat can be described by the pseudo-second order mechanism.",
Arsenic,1337325,"Complexation at the edges of hydrotalcite: The cases of arsenate and chromate Abstract: Sorption of CrO(4)(2-) and HAsO(4)(2-) by hydrotalcite, in its chloride form, was studied as a function of anion concentration. In both cases, the shape of the isotherms is langmuirian. The maximum uptake of CrO(4)(2-) equals the ion-exchange capacity of the solid, whereas sorption of HAsO(4)(2-) saturates at a higher value. Chloride ions inhibit the uptake of both anions, the amount of sorbed CrO(4)(2-) declining rapidly to zero. The uptake of HAsO(4)(2-), however, attains a constant value at high chloride concentrations. The excess of arsenate uptake follows, at constant pH, a langmuirian dependence with equilibrium concentration and decreases with increasing pH, depicting a marked change in slope at pH?pQ(a3). CrO(4)(2-) and HAsO(4)(2-) have notable, albeit different, effects on the electrophoretic behavior of hydrotalcite; the positive particle charge is screened almost completely by CrO(4)(2-), whereas sorption of HAsO(4)(2-) produces charge reversal. These results reflect the formation of inner-sphere arsenate surface complexes at the edges of hydrotalcite particles. The underlying rationale is discussed in terms of the crystal structure of hydrotalcite surfaces.",
Arsenic,1346276,"Determination of lead, cadmium, chromium, and arsenic in 13 herbs of tocolysis formulation using atomic absorption spectrometry Abstract: The contents of Pb, Cd, Cr, and As in 13 herbs of tocolysis formulations were studied using three kinds of sample pretreatment and atomic absorption spectrometry. Thirteen herbs were pretreated with either incineration, wet digestion, or microwave digestion, and the results of recoveries and precision about these elements were compared. The average recoveries of 13 herbs via incineration, wet digestion, and microwave digestion pretreatments were 80 ± 12%, 85.7 ± 3.3%, and 94.5 ± 2.1%, respectively. Among them, microwave digestion pretreatment had the highest recovery and precision. The average relative standard deviations for the four measured elements (Pb, Cd, Cr, and As) from incineration, wet digestion, and microwave digestion pretreatments were 8.8 ± 1.7%, 7.1 ± 3.3%, and 3.4 ± 0.8%, respectively. The detection limits for Pb, Cd, Cr, and As using microwave digestion pretreatment were 0.45 ppb, 0.03 ppb, 0.20 ppb, and 0.64 ppb, respectively. Concentrations of Pb, Cd, Cr, and As measured from the tocolysis formulation using microwave digestion pretreatment were 28.0 ± 0.7 ppb, 1.11 ± 0.03 ppb, 8.5 ± 0.3 ppb, and 1.52 ± 0.04 ppb, respectively. Lead was found to have the highest concentration among the four determined elements in 13 herbs. Schizonepetae Herba contained the highest Pb (60.5 ± 2.1 ppb), Cr (23.3 ± 0.5 ppb), and As (8.8 ± 0.1 ppb) among the 13 herbs. Ligustici Rhizoma contained the highest Cd (3.76 ± 0.04 ppb) among the 13 herbs.",
Arsenic,2149134,"Distribution and ecological assessment of heavy metals in surface sediments of the East Lake, China Abstract: Concentrations and risk assessment of chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), lead (Pb), cadmium (Cd) and mercury (Hg) were investigated in 106 samples of surface sediments from the East Lake, China in this study. The mean concentration of Zn was highest among the eight heavy metals (225 mg kg(-1)), followed by As (191 mg kg(-1)), Cr (145 mg kg(-1)), Cu (55 mg kg(-1)), Ni (27.1 mg kg(-1)), Pb (7.93 mg kg(-1)), Cd (0.94 mg kg(-1)) and Hg (0.21 mg kg(-1)). Niuchao Hu was less polluted by heavy metals compare to the other four lakelets of the East Lake. The correlations among these heavy metals and the results of principal component analysis indicated that the distribution of Cd, Pb and Hg was related to anthropogenic activities, whereas Cu, As and Cr were affected by the parent rocks. Zinc and Ni were influenced both by anthropogenic activities and parent rocks. Based on the Sediment Quality Guidelines, the results of toxicity assessment indicated that adverse effects caused by Cr and As would be expected frequently. Nickel, Zn, Cd and Hg may cause adverse effects occasionally and Cu and Pb may cause toxicity infrequently. Arsenic was found to have the highest acute toxicity by toxic units (TUs), followed by Cr, Ni, Zn, Hg, Cu, Cd and Pb. The potential ecological risk index analysis indicated that As, Cd and Hg had considerable or high ecological risk, whereas Cr, Ni, Cu, Zn and Pb had low ecological risk. The potential ecological risk index (RI) of the heavy metals in the surface sediments of East Lake was 483, indicating considerable ecological risk. Close attention should be paid to pollution of the heavy metals in East Lake, China.",
Arsenic,1380947,DETERMINATION OF ARSENIC RESIDUES IN AGRICULTURAL PRODUCTS OF MILOS ISLANDS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE OLIVE OIL FOOD RESIDUE FRUITS VEGETABLES RECOVERY DETECTION LIMIT SPECTROPHOTOMETRY ANALYTICAL METHOD GREECE,
Arsenic,627736,"Arsenic disruption of steroid receptor gene activation: Complex dose-response effects are shared by several steroid receptors Abstract: Chronic intake of arsenic (As) has been associated with increased risk of cancer, diabetes, developmental and reproductive problems, and cardiovascular disease. Recent studies suggest increased health risks with drinking water levels as low as 5-10 ppb. We previously reported that As disrupts glucocorticoid receptor (GR) mediated transcription in a very complex fashion. Low As levels (0.1-0.7 microM) stimulated transcription, whereas slightly higher levels (1-3 microM) were inhibitory. The DNA binding domain (DBD) was the minimal region of GR required for the response to As. Mutations in the DBD that alter the conformation of the dimerization domain (D-loop) to a DNA-bound GR conformation abolished the stimulatory effect and enhanced the inhibitory response to As. Here we report that receptors for progesterone (PR) and mineralocorticoids display a complex As response similar to that of the GR, suggesting a common mechanism for this effect. The complex response to As is not due to altered steroid or receptor levels. Moreover, a well-characterized GR dimerization mutant displayed a wild-type biphasic response to As for several divergent reporter genes, suggesting that dimerization is not critical for the response to As. Fluorescence polarization studies with purified PR and GR demonstrated that the specific PR/GR-DNA interaction is not altered in the presence of As. These results indicate that the numerous and diverse human health effects associated with As exposure may be mediated, at least in part, through its ability to simultaneously disrupt multiple hormone receptor systems.",
Arsenic,1016373,"The impact of mining activities in alteration of As levels in the surrounding ecosystems: an encompassing risk assessment and evaluation of remediation strategies Abstract: A comprehensive field survey was conducted to explore the status of arsenic (As) contamination in soil and water systems surrounding numerous abandoned mine sites in Korea, which were previously applied with soil-topping (15 cm deep) and lime treatment for remediation purposes. This survey also aimed to assess the environmental stability of those reservoirs in relation to their established guidelines for As. To this end, a total of 5837 target soils (TS) were analyzed along with 305 control soils (CS) and 74 tailing (TA) samples. In addition, analyses were also extended to cover 1066 water and 329 sediment samples. Substantial evidence (e.g., differences in the mean As levels between TS (12.7 mg kg(-1)) and CS (0.69 mg kg(-1)) and the strong correlation between TS and TA) suggests a strong effect of previous mining activities. Soil-topping method was successful in confining As at the subsurface soil and restraining its dispersal. Although soil pH level also dropped with increasing As, it was restored to near neutrality by liming treatment. The mean values of As in water samples are comparable between dry (22.2) and wet seasons (21.2 mg L(-1)), while its values frequently exceeded various guideline limits. The pollution status of the current land and water systems needs to be assessed properly along with a removal plan for mine wastes/tailings to limit the dispersion of As in the study area.",
Arsenic,1015811,"Association of glutathione S-transferase ? 1-1 polymorphisms (A140D and E208K) with the expression of interleukin-8 (IL-8), transforming growth factor beta (TGF-?), and apoptotic protease-activating factor 1 (Apaf-1) in humans chronically exposed to arsenic in drinking water Abstract: Human exposure to arsenicals is associated with inflammatory-related diseases including different kinds of cancer as well as non-cancerous diseases like neuro-degenerative diseases, atherosclerosis, hypertension, and diabetes. Interindividual susceptibility has been mainly addressed by evaluating the role of genetic polymorphism in metabolic enzymes in inorganic arsenic (iAs) metabolism. Glutathione S-transferase omega 1-1 (GSTO1-1), which had been associated with iAs metabolism, is also known to participate in inflammatory and apoptotic cellular responses. The polymorphism A140D of GSTO1-1 has been not only associated with distinct urinary profile of arsenic metabolites in populations chronically exposed to iAs in drinking water, but also with higher risk of childhood leukemia and lung disease in non-exposed populations, suggesting that GSTO1-1 involvement in other physiologic processes different from toxics metabolism could be more relevant than is thought. We evaluated the association of the presence of A140D and E208K polymorphisms of GSTO1-1 gene with the expression of genes codifying for proteins involved in the inflammatory and apoptotic response in a human population chronically exposed to iAs through drinking water. A140D polymorphism was associated with higher expression of genes codifying for IL-8 and Apaf-1 mainly in heterozygous individuals, while E208K was associated with higher expression of IL-8 and TGF-? gene, in both cases, the association was independently of iAs exposure level; however, the exposure to iAs increased slightly but significantly the influence of A140D and E208K polymorphisms on such genes expression. These results suggest an important role of GSTO1-1 in the inflammatory response and the apoptotic process and indicate that A140D and E208K polymorphisms could increase the risk of developing inflammatory and apoptosis-related diseases in As-exposed populations.",
Arsenic,1021823,"Regional assessment of groundwater quality for drinking purpose Abstract: Owing to limited surface water during a long-term drought, this work attempted to locate clean and safe groundwater in the Choushui River alluvial fan of Taiwan based on drinking-water quality standards. Because aquifers contained several pollutants, multivariate indicator kriging (MVIK) was adopted to integrate the multiple pollutants in groundwater based on drinking- and raw-water quality standards and to explore spatial uncertainty. According to probabilities estimated by MVIK, safe zones were determined under four treatment conditions-no treatment; ammonium-N and iron removal; manganese and arsenic removal; and ammonium-N, iron, manganese, and arsenic removal. The analyzed results reveal that groundwater in the study area is not appropriate for drinking use without any treatments because of high ammonium-N, iron, manganese, and/or arsenic concentrations. After ammonium-N, iron, manganese, and arsenic removed, about 81.9-94.9% of total areas can extract safe groundwater for drinking. The proximal-fan, central mid-fan, southern mid-fan, and northern regions are the excellent locations to pump safe groundwater for drinking after treatment. Deep aquifers of exceeding 200 m depth have wider regions to obtain excellent groundwater than shallow aquifers do.",
Arsenic,627597,"Respiratory effects and arsenic contaminated well water in Bangladesh Abstract: Arsenic in drinking water causes a widespread concern in Bangladesh, where a major proportion of tube wells is contaminated. Arsenic ingestion causes skin lesions, which is considered as definite exposure. A prevalence comparison study of respiratory effects among subjects with and without arsenic exposure through drinking water was conducted in Bangladesh. Exposed participants were recruited through health awareness campaign programs. Unexposed participants were randomly selected, where tubewells were not contaminated with arsenic. A total of 169 individuals participated (44 exposed individuals exhibiting skin lesions; 125 unexposed individuals). The arsenic concentrations ranged from 136 to 1000 micro g l(-1). The information regarding respiratory system signs and symptoms were also collected and the analyses were confined to nonsmokers. The crude prevalence ratio for chronic bronchitis and chronic cough amounted to 2.1 (95% CI 0.7-6.1). The prevalence ratios for chronic bronchitis increased with increasing exposure, i.e., 1.0, 1.6, 2.7 and 2.6 using unexposed as the reference. The prevalence ratios for chronic cough were 1.0, 1.6, 2.7 and 2.6 for the exposure categories, using the same unexposed as the reference. The dose-response trend was the same (P < 0.1) for both conditions. These results add to evidence that long-term ingestion of arsenic exposure can cause respiratory effects.",
Arsenic,1508533,"pH-Dependent reactivity of oxidants formed by iron and copper-catalyzed decomposition of hydrogen peroxide Abstract: The decomposition of hydrogen peroxide catalyzed by iron and copper leads to the generation of reactive oxidants capable of oxidizing various organic compounds. However, the specific nature of the reactive oxidants is still unclear, with evidence suggesting the production of hydroxyl radical or high-valent metal species. To identify the reactive species in the Fenton system, the oxidation of a series of different compounds (phenol, benzoic acid, methanol, Reactive Black 5 and arsenite) was studied for iron- and copper-catalyzed reactions at varying pH values. At lower pH values, more reactive oxidants appear to be formed in both iron and copper-catalyzed systems. The aromatic compounds, phenol and benzoic acid, were not oxidized under neutral or alkaline pH conditions, whereas methanol, Reactive Black 5, and arsenite were oxidized to a different degree, depending on the catalytic system. The oxidants responsible for the oxidation of compounds at neutral and alkaline pH values are likely to be high-valent metal complexes of iron and copper (i.e., ferryl and cupryl ions).",
Arsenic,1704091,"Transport of dissolved trace elements in surface runoff and leachate from a Coastal Plain soil after poultry litter application Abstract: The application of poultry (Gallus gallus domesticus) litter to agricultural soils may exacerbate losses of trace elements in runoff water, an emerging concern to water quality. We evaluated trace elements (arsenic [As], mercury [Hg], selenium [Se], and zinc [Zn]) in surface runoff and leachate from an agricultural soil with and without poultry litter application. Litter from a commercial operation was applied by three methods—broadcast application, subsurface placement, and broadcast application followed by disking—to no-till soils with a history of receiving litter. Soil monolith lysimeters (61 by 61 by 61 cm)(24 by 24 by 24 in) were extracted from each of the treatments and subjected to rainfall simulation (1 hour, 61 mm h?1 [2.4 in hr?1]) 15 and 42 days after litter application. Broadcasting poultry litter significantly increased concentrations (mg L?1) and loads (g ha?1) of As and Zn in runoff during the first event relative to other application methods. Notably, incorporating litter, either by disking after broadcasting or by subsurface placement, lowered As and Zn in runoff to near background levels by the second event, and there were no significant differences in As and Zn between any of the treatments. While Hg and Se were detected in runoff, they likely derived from edaphic sources as they were not detected in the litter nor did they differ significantly between treatments. Results point to poultry litter as a temporary source of some trace elements to runoff. This source can be readily controlled by adjusting application method.",
Arsenic,1018427,"The semiconductor elements arsenic and indium induce apoptosis in rat thymocytes Abstract: Indium arsenide and gallium arsenide are important new materials in the semiconductor industry due to their superior electronic properties in comparison with the older silicon-based materials. Animal experiments have shown that exposure to these compounds induces marked alterations in gene expression and immune response. Toxicity to the immune system has frequently been related to T and B cell apoptosis. In the present study we show that the semiconductor elements indium (In) and arsenic (As) are able to induce apoptosis in rat thymocytes in vitro. The results show that exposure to InCl3 (1, 10, or 100 ?M) or NaAsO2 (0.01, 0.1, or 1 microM) induced DNA laddering after 6 h of incubation without compromising cell viability. These results were corroborated by flow cytometry analysis of propidium iodide-loaded cells, showing a typical high hypodiploid DNA peak in apoptotic thymocytes. Higher doses of In (1 mM) or As (10-100 ?M) induced cell death by necrosis. These data indicate that In and As can induce apoptosis and necrosis in T lymphocytes in a dose-dependent manner, which may be of relevance for their immunotoxicity.",
Arsenic,1327388,"Cytotoxicological aspects of organic arsenic compounds contained in marine products using the mammalian cell culture technique Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenobetaine, arsenocholine, trimethylarsine oxide and tetramethylarsonium iodide, which are contained in marine fishery products, were examined for their potencies on cell growth inhibition, chromosomal aberration and sister chromatid exchange (SCE). Arsenobetaine, the major water-soluble organic arsenic compound in marine animals, exibited very low cytotoxicity towards mammalian cells. This compound showed no cell growth inhibition at a concentration of 10 mg cm-3 and the cytotoxicity was lower than 1/14000th of that of sodium arsenite and 1/1600th of that of sodium arsenate towards BALB/c 3T3 cells. The chromosomal aberrations caused by arsenobetaine at a concentration of 10 mg cm-3 consisted mainly of chromatid gaps and chromatid breaks, but in this concentration chromosomal breakage owing to its osmotic pressure is likely to be considerable. No SCE was observed at a concentration of 1 mg cm-3. Arsenocholine and trimethylarsine oxide also showed no cell growth inhib",
Arsenic,1349739,"Functional significance of conserved cysteines in the arsenic/antimony antiporter Acr3 from budding yeast Abstract: The Acr3 permease from the yeast Saccharomyces cerevisiae is aprototype member of the arsenical resistance-3 (Acr3) family oftransporters, which are found in all domains of life. Remarkablylittle is known about molecular mechanism of metalloid translo-cation via Acr3. Members of the Acr3 family exhibit ten-trans-membrane topology and lack any known sequence signatures,which could suggest mechanism of metalloid ?ow. It has beenrecently revealed that a single cysteine residue (Cys129) in theCorynebacterium glutamicum Acr3, which is located in the fourthtransmembrane span and conserved in all members of the Acr3family, is indispensable for As(III) ef?ux. We have found thatthe mutation of this highly conserved residue (C151A) in the S.cerevisiae Acr3 also led to a complete loss of transport function.This strongly suggests that interactions between As(III) and athiol group of this residue is required to activate transportthrough Acr3. In addition, we mutagenized the remaining threecysteine residues C192, C283, and C344, located also in the trans-membrane spans of Acr3, and found that in contrast to theC151A mutant, these mutant forms of Acr3 were able to comple-ment metalloid sensitivity of ACR3 deletion yeast strain andshowed only a slight decrease of ef?ux activity. Although, all cys-teine mutants of Acr3 were expressed at the wild type level, fourof them, C90A, C169A, C318A and C333A, were not properlysecreted to the plasma membrane and accumulated in the intra-cellular membranes, suggesting that these residues are requiredfor the ER exit. C90, C169, C318, and C333 are located in theintracellular loops and might be subjected to posttranslationalmodi?cations, like palmitoylation, which are required for mem-brane association, protein stability and protein traf?cking.",
Arsenic,2337144,"Fabrication of 3D porous Mn doped alpha-Fe2O3 nanostructures for the removal of heavy metals from wastewater Abstract: Three-dimensional porous Mn doped alpha-Fe2O3 nanostructures are successfully fabricated by calcined carbon spheres containing Fe(II) and Mn(II) ions, which were obtained by hydrothermal treatment of glucose, Fe(II), and Mn(II) mixed solutions. The obtained nanostructures exhibit excellent abilities for the removal of Pb(II), Cr(VI), and As(III) ions from wastewater with easy magnetic separation.",
Arsenic,1023776,"Arsenic release provided by MTA and Portland cement Abstract: OBJECTIVE: The aim of the present study was to determine the release of arsenic from 2 gray Portland cements, a white Portland cement, and 2 MTAs (ProRoot and MTA-Angelus).<br /><br /><strong>STUDY DESIGN: </strong>The materials were manipulated and placed in plastic tubes, and the tubes were immersed in glass flasks containing water with grade reagent, pH 5.0. After 3 and 168 h, the water in which the material had been immersed was analyzed regarding the presence of arsenic by atomic absorption spectrophotometry with hydride generation.<br /><br /><strong>RESULTS: </strong>The levels of arsenic released were similar for Portland cements and MTAs, and were well below those considered to be harmful.<br /><br /><strong>CONCLUSIONS: </strong>MTA and Portland cements showed very low arsenic presence. The results suggest that MTAs and Portland cements are safe for use in clinical practice in terms of the presence of arsenic.",
Arsenic,1021645,"Persistent exposure to arsenic via drinking water in rural Bangladesh despite major mitigation efforts Abstract: <strong>OBJECTIVES: </strong>Elevated arsenic levels in tube-well water in Bangladesh have prompted extensive mitigation projects. We evaluated the effectiveness of long-term mitigation efforts by longitudinally measuring arsenic exposure in pregnant women and their children, the most susceptible population groups.<br /><br /><strong>METHODS: </strong>The study was nested in a population-based nutrition intervention in Matlab, Bangladesh. Mother-child pairs (n = 1951) were followed from 2001 to 2003, beginning in early gestation and continuing to 5 years postpartum. We measured arsenic concentrations in urine (U-As) of the 5-year-old children by using high-performance liquid chromatography online with hydride generation and inductively coupled plasma mass spectrometry and compared them with earlier childhood U-As and maternal U-As during pregnancy.<br /><br /><strong>RESULTS: </strong>Children had elevated U-As at 5 years old (median = 51 ?g/L, 5th-95th percentiles = 16-355 ?g/L), and U-As distribution was similar to that observed in the mothers during gestation. Children's U-As at 5 years old significantly correlated with their U-As at 1.5 years old and to maternal U-As during early and late gestation.<br /><br /><strong>CONCLUSIONS: </strong>Despite major mitigation efforts, arsenic exposure remains highly elevated in rural Bangladesh. Further mitigation strategies are required and must be rigorously evaluated for long-term efficacy.",
Arsenic,1797807,"Curcumin attenuates arsenic-induced hepatic injuries and oxidative stress in experimental mice through activation of Nrf2 pathway, promotion of arsenic methylation and urinary excretion Abstract: Oxidative stress is one of the major mechanisms implicated in inorganic arsenic poisoning. Curcumin is a natural phenolic compound with impressive antioxidant properties. What's more, curcumin is recently proved to exert its chemopreventive effects partly through the activation of nuclear factor (erythroid-2 related) factor 2 (Nrf2) and its antioxidant and phase II detoxifying enzymes. In vivo, we investigated the protective effects of curcumin against arsenic-induced hepatotoxicity and oxidative injuries. Our results showed that arsenic-induced elevation of serum alanine amino transferase (ALT) and aspartate aminotransferase (AST) activities, augmentation of hepatic malonaldehyde (MDA), as well as the reduction of blood and hepatic glutathione (GSH) levels, were all consistently relieved by curcumin. We also observed the involvement of curcumin in promoting arsenic methylation and urinary elimination in vivo. Furthermore, both the hepatic Nrf2 protein and two typically recognized Nrf2 downstream genes, NADP(H) quinine oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), were consistently up-regulated in curcumin-treated mice. Our study confirmed the antagonistic roles of curcumin to counteract inorganic arsenic-induced hepatic toxicity in vivo, and suggested that the potent Nrf2 activation capability might be valuable for the protective effects of curcumin against arsenic intoxication. This provides a potential useful chemopreventive dietary component for human populations.",
Arsenic,2337231,"Geometrically enforced donor-facilitated dehydrocoupling leading to an isolable arsanylidine-phosphorane Abstract: A proximate Lewis basic group facilitates the mild dehydrogenative P-As intramolecular coupling in the phosphine-arsine peri-substituted acenaphthene 3, affording thermally and hydrolytically stable arsanylidine-phosphorane 4 with a sterically accessible two-coordinate arsenic atom. The formation of 4 is thermoneutral due to the dehydrogenation being concerted with the donor coordination. Reaction of 4 with a limited amount of oxygen reveals arsinidene-like reactivity via formation of cyclooligoarsines, supporting the formulation of the bonding in 4 as base-stabilized arsinidene R3P?AsR.",
Arsenic,627453,"Speciation of dimethylarsinous acid and trimethylarsine oxide in urine from rats fed with dimethylarsinic acid and dimercaptopropane sulfonate Abstract: Speciation of arsenic in urine from rats treated with dimethylarsinic acid (DMA(V)) alone or in combination with dimercaptopropane sulfonate (DMPS) were studied. Methods were developed for the determination of the methylarsenic metabolites, especially trace levels of dimethylarsinous acid (DMA(III)) and trimethylarsine oxide (TMAO), in the presence of a large excess of DMA(V). Success was achieved by using improved ion-exchange chromatographic separation combined with hydride generation atomic fluorescence detection. Micromolar concentrations of DMA(III) were detected in urine of rats fed with a diet supplemented with either 100 microg/g of DMA(V) or a mixture of 100 microg/g of DMA(V) and 5600 microg/g of DMPS. No significant difference in the DMA(III) concentration was observed between the two groups; however, there was a significant difference in TMAO concentrations. Urine from rats fed with the diet supplemented with DMA(V) alone contained 73 +/- 30 microM TMAO, whereas urine from rats fed with the diet supplemented with both DMA(V) and DMPS contained only 2.8 +/- 1.4 microM TMAO. Solutions containing mixtures of 100 microg/L DMA(V) or TMAO and 5600 microg/L DMPS did not show reduction of DMA(V) and TMAO. The significant decrease (p &lt; 0.001) of the TMAO concentration in rats administered with both DMA(V) and DMPS suggests that DMPS inhibits the biomethylation of arsenic.",
Arsenic,1387021,"Physiological profiling of indigenous aquatic microbial communities to determine toxic effects of metals Abstract: BIOSIS COPYRIGHT: BIOL ABS. Conventional bioassays for environmental assessment frequently rely on nonindigenous single species. We employed an assay in which whole environmental samples were distinguished by the ability of the native heterotrophic microbial communities to oxidize 95 different sole carbon sources generating a community-level physiological profile (CLPP). The average metabolic response (AMR) to the 95 variables defining the CLPP was used in laboratory bioassay studies with copper to construct dose-response curves over several different periods of exposure: 1 h (acute), 1 d, 2 d, and 4 d. The acute dose-response of Snake River bacterioplankton communities measured by AMR was compared to the dose-response of Photobacterium phosphoreum (used in the Microtox test) and a proprietary mixed consortia (used in the Polytox test). In laboratory bioassay studies, CLPP AMR exhibited acute dose-response behavior over a greater range in copper concentrations and with less variability (per dose)",
Arsenic,2337269,"Purification, crystallization and preliminary X-ray diffraction analysis of ArsH from Synechocystis sp. strain PCC 6803 Abstract: ArsH is an NADPH-dependent flavin mononucleotide reductase and is frequently encoded as part of an ars operon. The function of the arsH gene remains to be characterized. Crystallization and structural studies may contribute to elucidating the specific biological function of ArsH associated with arsenic resistance. ArsH from Synechocystis sp. strain PCC 6803 was overproduced, purified and crystallized. Crystals were obtained by the sitting-drop vapour-diffusion method. Diffraction data were collected and processed to a resolution of 1.6?Å. The crystals belonged to the tetragonal space group I4122, with unit-cell parameters a = b = 127.94, c = 65.86?Å and one molecule in the asymmetric unit. Size-exclusion chromatography and molecular-replacement results showed that the ArsH formed a tetramer. Further structural analysis and comparison with ArsH from Sinorhizobium meliloti will provide information about the oligomerization of ArsH.",
Arsenic,1579268,Hazardous and harmful substances in sediments of the Jegricka stream Abstract: ,
Arsenic,2149357,Sustainable Arsenic Mitigation (SASMIT): An approach for developing a color based tool for targeting arsenic-safe aquifers for drinking water supply Abstract: ,
Arsenic,2149343,Arsenic removal by traditional and innovative membrane technologies Abstract: ,
Arsenic,1031828,"Dimethylated arsenics induce DNA strand breaks in lung via the production of active oxygen in mice Abstract: In order to study the genotoxicity of arsenics, we focused our attention on dimethylarsinic acid (DMAA) which was a main metabolite of inorganic arsenics in mammals. ICR mice were orally administered DMAA-Na (1500mg/kg). DNA single-strand breaks occurred specifically in lung at 12h after administration. An in vitro experiment indicated that the breaks were not caused directly by DMAA but by dimethylarsine, a further metabolite of DMAA. Furthermore, the dimethylarsine-induced breaks were diminished by the addition of SOD and catalase, suggesting that active oxygen produced by dimethylarsine was involved in the induction of DNA damage.",
Arsenic,2298684,"Functional coexistence of twin arsenic resistance systems in Pseudomonas putida KT2440 Abstract: The genome of the soil bacterium Pseudomonas putida KT2440 bears two virtually identical arsRBCH operons putatively encoding resistance to inorganic arsenic species. Single and double chromosomal deletions in each of these ars clusters of this bacterium were tested for arsenic sensitivity and found that the contribution of each operon to the resistance to the metalloid was not additive, as either cluster sufficed to endow cells with high-level resistance. However, otherwise identical traits linked to each of the ars sites diverged when temperature was decreased. Growth of the various mutants at 15 °C (instead of the standard 30 °C for P. putida) uncovered that ars2 affords a much higher resistance to As (III) than the ars1 counterpart. RT-PCR of arsB1 and arsB2 genes and lacZ fusions to the Pars1 and Pars2 promoters traced the difference to variations in transcription of the corresponding gene sets at each temperature. Functional redundancy may thus be selected as a stable condition -rather than just as transient state- if it affords one key activity to be expressed under a wider range of physicochemical settings. This seems to provide a straightforward solution to regulatory problems in environmental bacteria that thrive under changing scenarios.",
Arsenic,1029977,"Selection and processing of infrared materials Abstract: The similarities and differences between specifications and fabrication techniques for optical glass and for ir materials are discussed. A general familiarity with this subject as applied to the visible region is assumed. Of the many materials known to transmit ir radiation, a group of nine is selected for emphasis; reasons are given for this selection, and specific comments made on each material. Those suggested for general use are germanium, silicon, arsenic trisulfide, KRS-5, Irtran-2 and -4, and for restricted uses strontium titanate, Irtran-1, and indium antimonide.",
Arsenic,1349894,Adsorption kinetic control of As(III & V) mobilization and sequestration by Mangrove sediment Abstract: ,
Arsenic,1797848,"Biovolatilisation: a poorly studied pathway of the arsenic biogeochemical cycle Abstract: It has been known for over a hundred years that microorganisms can produce volatile arsenic (As) species, termed &quot;arsines&quot;. However, this topic has received relatively little attention compared to As behaviour in soils and biotransformation through the trophic level in the marine and terrestrial environment. We believe this is due to long-standing misconceptions regarding volatile As stability and transport as well as an absence, until recently, of appropriate sampling methods. First and foremost, an attempt is made to unify arsines' designations, notations and formulas, taking into account all the different terms used in the literature. Then, the stability of As volatile species is discussed and new analytical developments are explored. Further, the special cases of diffuse low-level emissions (e.g. soil and sediment biovolatilisation), and point sources with high-level emissions (geothermal environments, landfills, and natural gas) are comprehensively reviewed. In each case, future possible areas of research and unknown mechanisms are identified and their importance towards the global As biogeochemical cycle is explored. This review gathers new information regarding mechanisms, stability, transport and sampling of the very elusive arsines and shows that more research should be conducted on this important process.",
Arsenic,1337524,"Retinal pigment epithelial cell loss assessed by fundus autofluorescence imaging in neovascular age-related macular degeneration Abstract: PURPOSE: To characterize retinal pigment epithelial (RPE) cell loss as evidenced by autofluorescence imaging in patients with neovascular age-related macular degeneration (AMD). DESIGN: Retrospective cohort study. PARTICIPANTS: There were 162 eyes of 116 consecutive patients with neovascular AMD examined in a retinal practice. METHODS: Each patient underwent a complete examination including autofluorescence imaging. Areas of confluent absence of autofluorescence signal of at least 0.5 mm in greatest linear diameter were measured within the macular area. Patient demographic and examination data were evaluated in relation to the autofluorescence data. MAIN OUTCOME MEASURES: Prevalence and progression of confluent areas of absent autofluorescence and the relationship these areas had with visual acuity. RESULTS: The mean age of the patients was 82.9 years, and the mean visual acuity was 20/71 (logarithm minimum angle of resolution [logMAR], 0.55). Confluent loss of autofluorescence was seen in 58.6% of eyes at baseline, and the median area of absent autofluorescence among those was 1.57 mm(2) (interquartile range [IQR], 0.62-4.32 mm(2)). Using generalized estimation equation modeling, the significant predictors for area of confluent absent autofluorescence at baseline were duration of disease and any previous treatment with photodynamic therapy. The significant predictor of baseline visual acuity was baseline area of confluent absent autofluorescence. Follow-up was available for 124 (76.5%) eyes, with a mean follow-up of 2.9 years. By then, the mean visual acuity was 20/90 (logMAR, 0.65), and 79% of eyes had confluent areas of absent autofluorescence, the large majority of which affected the central macula. The median area of absent autofluorescence was 3.61 mm(2) (IQR, 1.16-7.11 mm(2)). The best predictor of final visual acuity was the area of absent autofluorescence at the final follow-up. CONCLUSIONS: Confluent absence of autofluorescence, a measure signifying RPE loss, was a significant predictor of visual acuity both at baseline and at final follow-up. This is the first study to document the prevalence, rate of progression, and factors associated with measures of confluent RPE loss in patients with neovascular AMD. Application of strategies to limit RPE cell loss may prove useful in eyes with neovascular AMD. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.",
Arsenic,1025816,"GSK3 promotes arsenite-induced apoptosis via facilitation of mitochondria disruption Abstract: Arsenic is an environmental toxicant that recently has been shown to have anticancer activity against a number of types of cancer cells by inducing apoptosis. Glycogen synthase kinase-3 (GSK3), a serine/threonine kinase, is an important pro-apoptotic signaling enzyme. Although GSK3 has been shown to promote apoptosis caused by a wide variety of insults, a role for GSK3 in arsenic-induced apoptosis has not yet been identified. Investigation of the involvement of GSK3 in arsenite-induced apoptosis demonstrated that arsenite induced apoptosis in SH-SY5Y human neuroblastoma cells, activating the executioner caspase-3 which caused cleavage of poly-ADP ribose-polymerase (PARP). Two selective GSK3 inhibitors, lithium and SB216763, attenuated caspase-3 activation and PARP cleavage induced by arsenite treatment indicating that GSK3 contributed to arsenite-induced apoptosis. Apoptotic signaling following exposure to arsenite involved cytochrome C release from mitochondria, and this was reduced by inhibition of GSK3 indicating that GSK3 promotes arsenite-induced apoptotic signaling upstream of mitochondrial disruption. Moreover, arsenite induced the translocation of Bax and p53 to the mitochondria and the activation-associated oligomerization of Bax, and these crucial events were reduced by inhibition of GSK3, indicating that GSK3 promotes arsenite-induced apoptosis by facilitating signals leading to mitochondrial apoptotic events. Taken together, the findings from this study reveal that GSK3 promotes arsenite-induced apoptosis by facilitating signaling leading to disruption of mitochondria.",
Arsenic,1677517,"The removal of arsenate from water using iron-modified diatomite (D-Fe): isotherm and column experiments Abstract: Iron hydroxide supported onto porous diatomite (D-Fe) is a low-cost material with potential to remove arsenic from contaminated water due to its affinity for the arsenate ion. This affinity was tested under varying conditions of pH, contact time, iron content in D-Fe and the presence of competitive ions, silicate and phosphate. Batch and column experiments were conducted to derive adsorption isotherms and breakthrough behaviours (50 ?g L(-1)) for an initial concentration of 1,000 ?g L(-1). Maximum capacity at pH 4 and 17 % iron was 18.12-40.82 mg of arsenic/g of D-Fe and at pH 4 and 10 % iron was 18.48-29.07 mg of arsenic/g of D-Fe. Adsorption decreased in the presence of phosphate and silicate ions. The difference in column adsorption behaviour between 10 % and 17 % iron was very pronounced, outweighing the impact of all other measured parameters. There was insufficient evidence of a correlation between iron content and arsenic content in isotherm experiments, suggesting that ion exchange is a negligible process occurring in arsenate adsorption using D-Fe nor is there co-precipitation of arsenate by rising iron content of the solute above saturation.",
Arsenic,2278794,"Arsenic distribution and speciation near rice roots influenced by iron plaques and redox conditions of the soil matrix Abstract: Elevated arsenic (As) concentrations in rice and the soil solution result from changes in soil redox conditions, influenced by the water management practices during rice cultivation. Microscale changes in redox conditions from rhizosphere to soil matrix affect the As speciation and Fe plaque deposition. In order to focus on the rhizosphere environment, we observed microscale distribution and speciation of As around the rhizosphere of paddy rice with X-ray fluorescence mapping and X-ray absorption spectroscopy. When the soil matrix was anaerobic during rice growth, Fe-plaque did not cover the entire root, and As(III) was the dominant arsenic species in the soil matrix and rhizosphere. Draining before harvest led the conditions to shift to aerobic. Oxidation of As(III) to As(V) occurred faster in the Fe-plaque than the soil matrix. Arsenic was scavenged by iron mottles originating from Fe-plaque around the roots. The ratio of As(V) to As(III) decreased toward the outer-rim of the subsurface Fe mottles where the soil matrix was not completely aerated. These results provide direct evidence that speciation of As near rice roots depends on spatial and temporal redox variations in the soil matrix.",
Arsenic,628442,"Prevalence of chronic diseases in adults exposed to arsenic-contaminated drinking water Abstract: Inorganic arsenic is naturally occurring in groundwaters throughout the United States. This study investigated arsenic exposure and self-report of 9 chronic diseases. We received private well-water samples and questionnaires from 1185 people who reported drinking their water for 20 or more years. Respondents with arsenic levels of 2 ?g/L or greater were statistically more likely to report a history of depression, high blood pressure, circulatory problems, and bypass surgery than were respondents with arsenic concentrations less than 2 ?g/L.",
Arsenic,1029245,"Arsenicals produce stable progressive changes in DNA methylation patterns that are linked to malignant transformation of immortalized urothelial cells Abstract: Aberrant DNA methylation participates in carcinogenesis and is a molecular hallmark of a tumor cell. Tumor cells generally exhibit a redistribution of DNA methylation resulting in global hypomethylation with regional hypermethylation; however, the speed in which these changes emerge has not been fully elucidated and may depend on the temporal location of the cell in the path from normal, finite lifespan to malignant transformation. We used a model of arsenical-induced malignant transformation of immortalized human urothelial cells and DNA methylation microarrays to examine the extent and temporal nature of changes in DNA methylation that occur during the transition from immortal to malignantly transformed. Our data presented herein suggest that during arsenical-induced malignant transformation, aberrant DNA methylation occurs non-randomly, progresses gradually at hundreds of gene promoters, and alters expression of the associated gene, and these changes are coincident with the acquisition of malignant properties, such as anchorage independent growth and tumor formation in immunocompromised mice. The DNA methylation changes appear stable, since malignantly transformed cells removed from the transforming arsenical exhibited no reversion in DNA methylation levels, associated gene expression, or malignant phenotype. These data suggest that arsenicals act as epimutagens and directly link their ability to induce malignant transformation to their actions on the epigenome.",
Arsenic,1019683,"Determination of the total arsenic concentration in human urine by inductively coupled plasma mass spectrometry: A comparison of the accuracy of three analytical methods Abstract: Measurement of arsenic (As) in biological samples such as urine has important clinical applications and is being undertaken more frequently in epidemiologic studies because of concern about the carcinogenicity of low to moderate levels of As exposure. The objective of this study was to evaluate and improve the accuracy of As determination in urine by inductively coupled plasma mass spectrometry (ICP-MS). Determination of As in biological samples by ICP-MS is difficult for two reasons: the formation of the molecular ion 40Ar35Cl, which overlaps with monoisotopic As at a mass-to-charge ratio (m/z) of 75 (causing spectral interference), and signal enhancement due to organic matrix (nonspectral interference). Available procedures were examined, including the application of different correction procedures using 40Ar37Cl and 16O35Cl molecular-ion formation; the addition of N2 into plasma or nebulizer gas flows; and the addition of organic molecules to the sample and to calibration standards to eliminate or correct for interference due to molecular-ion formation. The accuracy and precision of determination of As [m/z 75, ionization potential (IP) 9.81 eV] with use of an internal standard was also investigated. Three elements were studied as candidate internal standards: germanium (Ge: m/z 74, IP 7.90 eV), indium (In: m/z 115, IP 5.79 eV), and tellurium (Te: m/z 128, IP 9.01 eV). It was found that these three elements performed more or less equally well with Ar-N2 plasma; it was also found that accuracy was significantly improved when Te was used as the internal standard instead of Ge or In for ethanol-added samples. Our results indicate that accurate and precise measurement of As in urine by ICP-MS can be obtained by either of two methods (&lt; 5% error, approximately 2% RSD, limit of detection 0.1 ng ml-1): (1) the addition of 1% N2 to plasma gas flow or 3% N2 to nebulizer gas flow, along with use of any of the internal standards tested, or (2) the addition of ethanol to the sample and to calibration standards, with use of Te as the internal standard. The most accurate results (&lt; 1% error) for National Institute of Standard and Technology Standard Reference Material (NIST SRM) 2670 (toxic elements in urine) were obtained with Ar-N2 plasma with either Te or In as the internal standard.",
Arsenic,1597308,"Association of blood lead and mercury with estimated GFR in herbalists after the ban of herbs containing aristolochic acids in Taiwan Abstract: OBJECTIVE: This study was undertaken to explore the association of estimated glomerular filtration rate (GFR) with exposure to aristolochic acids (ALAs) and nephrotoxic metals in herbalists after the ban of herbs containing ALAs in Taiwan. METHODS: This cross-sectional study recruited a total of 138 herbalists without end-stage renal disease or urothelial carcinoma from the Occupational Union of Chinese Herbalists in Taiwan in 2007. Aristolochic acid I (ALA-I) was measured by ultra-high-pressure liquid chromatography/ tandem mass spectrometry (UHPLC-MS/MS) and heavy metals in blood samples were analysed by Agilent 7500C inductively coupled plasma-mass spectrometry. Renal function was assessed by using a simplified Modification of Diet in Renal Disease Study equation to estimate GFR. RESULTS: Blood lead was higher in herbal dispensing procedures (p=0.053) and in subjects who self-prescribe herbal medicine (p=0.057); mercury was also higher in subjects living in the workplace (p=0.03). Lower estimated GFR was significantly associated with lead (?=-10.66, 95% CI -18.7 to -2.6) and mercury (?=-12.52, 95% CI -24.3 to -0.8) with a significant interaction (p=0.01) between mercury and lead; however, estimated GFR was not significantly associated with high ALA-I level groups, arsenic and cadmium after adjusting for other confounding factors. CONCLUSIONS: We found that lower estimated GFR was associated with blood lead and mercury in herbalists after the ban of herbs containing ALAs in Taiwan. The ALA-I exposure did not show a significant negative association of estimated GFR, which might due to herbalists having known how to distinguish ALA herbs after the banning policy. Rigorous monitoring is still needed to protect herbalists and the general population who take herbs.",
Arsenic,1342458,"A comparison of water treatment sludge and red mud as adsorbents of As and Se in aqueous solution and their capacity for desorption and regeneration Abstract: The adsorption of As(III), As(V), Se(IV) and Se(VI) by seawater neutralized red mud and alum water treatment sludge was investigated and compared using the batch adsorption technique. For water treatment sludge, adsorption of As(V), Se(IV) and Se(VI), at equimolar concentrations of added metalloid, declined with increasing pH. The decline was rapid above pH 4.0 for Se(VI), above pH 5.0 for Se(IV) and above pH 6.0 for As(V). Adsorption of As(III) increased with increasing pH up to pH 9.0 and then declined. For red mud, adsorption of As(V), Se(IV) and Se(VI) showed a maximum at about pH 5.0 and for As(III) adsorption remained relatively constant over the pH range 2.0–10.0 after which it declined. Water treatment sludge removed 50 % or more of solution As(V) between pH 2.0 and 10.8, Se(IV) between 2.0 and 8.9, Se(VI) between 2.0 and 5.8 and As(III) between 8.4 and 10.9. By contrast, red mud showed less than 25 % adsorption of added Se(VI) and As(III) over the entire pH range tested (2.0–12.0) and reached 50 % or more for As(V) only over the pH range 4.0–6.9 and for Se(IV) between pH 4.3 and 5.6. At pH 5.0, adsorption of As(III) and Se(IV) was better described by the Langmuir than Freundlich equation but the reverse was the case for As(V) and Se(VI). Kinetic data for adsorption of all four oxyanions onto both adsorbents correlated well with a pseudo-second-order kinetic model suggesting the process involved was chemisorption. NaOH was more effective at removing adsorbed metals from both adsorbents than HNO3. Water treatment sludge maintained its As(III) and Se(IV) adsorption capability at greater than 70 % of that added over eight successive cycles of adsorption/regeneration using 0.5 M NaOH as a regenerating agent. By contrast, for red mud, As(V) adsorption capacity declined very rapidly after three adsorption/desorption cycles and that for Se(IV) it decreased progressively with increasing numbers of cycles. It was concluded that water treatment sludge is a suitable material to develop as a low-cost adsorbent for removal of heavy metal oxyanions from wastewater streams.",
Arsenic,1508710,"An unusual fan-type polyanion with a silver cation located at the axial center, [AgAs(III)(2)(As(III)As(V)Mo(4)O(18)(OH)(2))(3)](11-) Abstract: A new type of polyoxomolybdate containing mixed-valence arsenic, [AgAs(III)(2)(As(III)As(V)Mo(4)O(18)(OH)(2))(3)](11-) (1), has been synthesized. Single-crystal X-ray analysis was carried out on (NH(4))(5)(C(2)H(9)N(2))(4.5)H(1.5)[AgAs(III)(2)(As(III)As(V)Mo(4)O(18)(OH)(2))(3)]·14H(2)O (1a) and (NH(4))(11)[AgAs(III)(2)(As(III)As(V)Mo(4)O(18)(OH)(2))(3)]·16H(2)O (1b). The polyanion is composed of three unprecedented [As(III)As(V)Mo(4)O(18)(OH)(2)](6-) subunits linked together by two AsO(3) trigonal-pyramidal structures from both sides via sharing six bridging oxygen atoms, and a silver cation is enclosed in the center of the polyanion and coordinated by three As atoms with the As-Ag-As bond angle of 120°, to lead to a fan-like structure with an approximative C(3h) symmetry. The polyanion was also characterized by IR, X-ray photoelectron spectroscopy and thermogravimetry-differential scanning calorimetry. The stability of [AgAs(III)(2)(As(III)As(V)Mo(4)O(18)(OH)(2))(3)](11-) in an aqueous solution was investigated by electronic absorbance spectroscopy and electrospray ionization mass spectrometry, and the possible disaggregation mechanism of the polyanion is proposed.",
Arsenic,1366872,"Relationships between thermotolerance, oxidative stress responses and induction of stress proteins in human tumour cell lines Abstract: Thermotolerance, resistance to oxidative stress and induction of stress proteins were examined in a panel of 10 human tumour cell lines. An inverse relationship was indicated between intrinsic thermotolerance (cell survival after treatment at 43.5 degrees for 3 hr) and thermotolerance induced by pretreatment at 42.5 degrees for 30 min. Similar levels of induction of hsp 70 were found in cell lines with high or low levels of intrinsic thermotolerance; induction of other stress proteins could not be detected. Cell survival following treatment with H2O2 correlated with that following streptonigrin treatment (P &lt; 0.05). Pretreatment with buthionine sulphoximine or diamide synergistically increased the toxicity of heat, H2O2 and streptonigrin whereas reduced glutathione had the reverse effect. No direct correlation was found, however, between tolerance to heat and to oxidative stress, and hsp 70 was not induced by the latter. The stress protein heme oxygenase, detected by immunoblotting with the monoclonal antibody HO, was induced by H2O2 in melanoma cell lines but not in HeLa. Cadmium and arsenite ions, however, readily induced heme oxygenase in HeLa, indicating that in these cells induction of heme oxygenase by oxidative stress involves a different mechanism. Overall, the results suggest that tolerance to heat or oxidative stress in these cell lines may not necessarily be associated with the induction of heat shock proteins or heme oxygenase but that cell survival after both types of stress depends to a certain extent on cellular sulphydryls.",
Arsenic,2345791,"Geochemical behavior of metals and metalloids in an estuary affected by acid mine drainage (AMD) Abstract: The Tinto and Odiel rivers in southwest Spain drain the world's largest sulfide mineral formation: the Iberian Pyrite Belt which has been worked since 2,500 BC. The Tinto and Odiel estuarine zones include both an extensive area of salt marsh and an intensively industrialized urban area. As a consequence of pyrite oxidation, the Tinto and Odiel rivers are strongly acidic (pH?&lt;?3) with unusually high and quite variable metal concentrations. In this study, seasonally varying concentrations of dissolved major and trace elements were determined in the acid mine drainage affected estuary of the Ría de Huelva. During estuarine mixing, ore-derived metal concentrations exhibit excellent correlations with pH as the main controlling parameter. As pH increases, concentrations of dissolved ore-associated elements are attenuated, and this process is enhanced during the summer months. The decrease in Fe and Al concentrations ranged from 80 to 100 % as these elements are converted from dissolved to sediment-associated forms in the estuary. Coprecipitation/adsorption processes also removed between 60 and 90 % of the originally dissolved Co, Cu, Mn, Pb, Zn, and Th; however, Cd and Ni exhibited a greater propensity to remain in solution, with an average removal of approximately 60 %. On the other hand, As and U exhibited a different behavior; it is likely that these elements remain in dissolved forms because of the formation of U carbonates and soluble As species. Concentrations of As remain at elevated levels in the outer estuary (average?=?48 ?g L(-1)) which exceeds concentrations present in the Tinto River. Nevertheless, the estuary has recently witnessed improvements in water quality, as compared to results of several previous studies reported in the 1990s.",
Arsenic,1031770,"An epidemiological study on cancer in certified arsenic poisoning patients in Toroku Abstract: A mortality study has been made to assess the carcinogenic effect of arsenic exposure by analyzing a group of certified chronic arsenic poisoning patients at a small mining village in Japan. When compared with expected number of deaths, based on sex-, age-specific mortality of Japanese in 1975, '80 and '85, all cancer, cancer of respiratory system and cancer of bladder, kidney and other and unspecified urinary organs showed a significant excess over the expected number. Divided by employment history, death due to all cancers, to respiratory cancer and to urinary tract cancer showed a significant excess among former workers of the mine. Classified into four cohorts by both employment history and smoking habit, death from respiratory cancer showed a significant excess only in the cohort respiratory cancer showed a significant excess only in the cohort of former workers with smoking history, suggesting an interaction between exposure to arsenic and smoking. Eight cases among ten respiratory cancers and two urinary tract cancer cases were accompanied by cancer of other organs, including Bowen's disease.",
Arsenic,1338698,"Role of EDTA in arsenic mobilization and its uptake by maize grown on an As-polluted soil Abstract: EDTA amendments are widely used for micronutrient fertilization in arid soils, besides their effectiveness in the remediation process of heavy metal from contaminated soils. However, the persistence of EDTA in arsenic contaminated soil may have further negative effects on the grown plants. To investigate the influences of EDTA on soil As, a pot experiment was conducted using a sandy clay loam As-polluted soil treated with gradual rates of EDTA (0, 1.0, 2.5 and 5mmolkg(-1)) and planted with maize for two months. The key findings reveal that EDTA applications increased AB-DTPA extractable and water soluble As significantly. Such increases seemed to be the main reasons behind the increase in As uptake by maize plants as the addition of EDTA at the rates of 1.0, 2.5 and 5.0mmolkg(-1) increased significantly As uptake by shoots 1.5, 2.4 and 3.0 folds, respectively compared to the untreated soil. On the other hand, As uptake by roots did not increase significantly except with the highest application rates of 2.5 and 5.0mmolkg(-1). The results also show that arsenic translocation factor (TF) values were too low to attain successful phytoextraction. In conclusion, the bioavailable fraction of As is important to investigate the phytoextraction and phytotoxicity of As.",
Arsenic,2088372,Enhancement of arsenic mobility by Fe(III)-reducing bacteria from iron oxide minerals Abstract: ,
Arsenic,1251165,"Assessing the risk to nontarget organisms from Bt corn resistant to corn rootworms (Coleoptera: Chrysomelidae): Tier-I testing with Orius insidiosus (Heteroptera: Anthocoridae) Abstract: A 14-d continuous dietary exposure bioassay using nymphs of the insidious flower bug, Orius insidiosus (Say) (Heteroptera: Anthocoridae), was conducted to assess nontarget impacts of genetically modified corn event MON 863 expressing the Cry3Bb1 protein for management of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae). Nymphs of O. insidiosus were continuously fed a bee pollen diet inoculated with a maximum hazard exposure dose (930 microg/g of diet) of the Cry3Bb1 protein for 14 d. The Cry3Bb1 protein at a concentration of 930 microg/g of diet had no adverse effect on the survival and development (to adults) of O. insidiosus nymphs. In contrast, when O. insidiosus nymphs were fed bee pollen diet treated with a hazard dose of the protease inhibitor E64 (53 microg/g of diet) or the stomach poison potassium arsenate (8.9 microg/g of diet), all nymphs died before developing to adults. Furthermore, statistical power analysis indicated that at levels of 80% power and a 5% type I error rate, the study design would have been able to detect a minimum 30% reduction in survival of test nymphs and a 20% reduction in nymphal development to the adults relative to the buffer control groups. Based on the maximum level (93 microg/g) of the Cry3Bb1 protein expressed in MON 863 corn tissues including leaves, roots, and pollen, findings from this study indicate that corn hybrids containing the MON 863 event have a minimum 10 times safety factor for nymphs of O. insidiosus and thus pose minimal risk to this beneficial insect.",
Arsenic,2064168,Arsenic and chromium reduction in co-cultures of bacteria isolated from industrial sites in Pakistan Abstract: ,
Arsenic,1797765,"Protective effect of Juglans nigra on sodium arsenite-induced toxicity in rats Abstract: <strong>BACKGROUND: </strong>Consumption of arsenic contaminated water has been implicated in metalloid-induced carcinogenesis. Dietary intake of certain plant products with chemoprotective properties may protect against the onset of diseases and promote maintenance of health.<br /><br /><strong>OBJECTIVES: </strong>We investigated the outcome of black walnut Juglans nigra (JN) consumption on sodium arsenite (SA)-induced toxicity in rats.<br /><br /><strong>MATERIALS AND METHODS: </strong>WISTER ALBINO RATS WERE TREATED AS FOLLOWS: Control, SA only (positive control) (2.5 mg/kg body weight), JN only (100 mg/kg weight), and JN+SA coadministered. After 5 weeks animals were sacrificed whole blood, femur, liver and testis harvested were assessed for hepatic transaminases and clastogenicity. Histology of the liver, sperm morphology and quality were also assessed. Data were analyzed (ANOVA) and expressed as means ±SD.<br /><br /><strong>RESULTS: </strong>SA treatment elevated hepatic transaminases level in serum (P < 0.05), induced histological changes in liver: fibroplasia and periportal hepatocytes infiltration by mononuclear cells. These changes were ameliorated by JN (P < 0.05) coadministration. SA induced micronuclei formation (P < 0.05). Again JN decreased (P < 0.05) micronuclei formation by 50%. Sperm count and motility decreased (P < 0.05) in all groups compared to control.<br /><br /><strong>CONCLUSION: </strong>JN showed no protection against arsenite effect on sperm quality. Hepatoprotective and anticlastogenic effects were apparent suggesting a chemopreventive potential active against arsenite genotoxicity and chromosomal instability which have implication for metalloid-induced carcinogenesis.",
Arsenic,59029,"Oxidative stress induced by lead, cadmium and arsenic mixtures: 30-day, 90-day, and 180-day drinking water studies in rats: An overview Abstract: Humans are frequently exposed to combinations of lead (Pb), cadmium (Cd) and Arsenic (As) but there is a paucity of actual data on the molecular effects of these agents at low dose levels. The present factorial design studies were undertaken in rats to examine the effects of these agents at LOEL dose levels on a number of molecular parameters of oxidative stress in hematopoietic and renal organ systems following oral exposure in drinking water at 30, 90 and 180 day time points. Results of these studies demonstrated dynamic, time-dependent alterations in both molecular targets and inducible oxidative stress protective systems in target cell populations. In general, cellular protective systems, which protected against oxidative damage at the 90 day time point, appeared to be finite such that molecular manifestations of oxidative stress became statistically significant at the 180 day time point for several of the combination exposure groups. These data demonstrate the importance of duration of exposure in assessing the toxic potential of Pb, Cd and As mixtures at low dose levels.",
Arsenic,734887,"Arsenic activates EGFR pathway signaling in the lung Abstract: Arsenic is an established lung carcinogen, however, the carcinogenic mechanisms are currently under investigation. Phosphorylation of the epidermal growth factor receptor (EGFR) has been reported with arsenic exposure in bladder cells. EGFR is a tyrosine kinase transmembrane receptor that regulates important processes in carcinogenesis, including cell survival, cell cycle progression, tumor invasion, and angiogenesis. We investigated the mechanisms of EGFR pathway activation by levels of arsenic relevant to human exposure scenarios both in vitro using cultured lung epithelial cells, and in lung tumors samples from New England Lung Cancer Study participants. Toenail arsenic levels were used as an internal biomarker of arsenic exposure. Our in vitro data suggest that arsenic increases levels of the EGFR ligand, heparin binding-EGF, and activate EGFR phosphorylation in the lung. Downstream of EGFR, arsenic exposure increased pERK and cyclin D1 levels. These effects were inhibited by treatment of cultured cells with the EGFR tyrosine kinase inhibitor, Tarceva (erlotinib). In a consecutive series of human lung tumor specimens, pEGFR protein levels were higher in subjects with elevated toenail arsenic levels compared to those with low exposure (odds ratio adjusted for other factors, OR 4.1 (95% confidence interval 1.1-15.6) (p = 0.04). These data suggest that arsenic exposure may stimulate EGFR pathway activation in the lung. Moreover, the tumors that arise in arsenic-exposed individuals also exhibit signs of EGFR pathway dysregulation. Further work is needed to assess the clinical utility of targeting the EGFR pathway in subgroups of lung cancer patients who have been exposed to elevated levels of arsenic.",
Arsenic,2278503,"Effects of soil type and fertilizer on As speciation in rice paddy contaminated with As-containing pesticide Abstract: Inorganic arsenic (As) pesticides have been widely used for decades in many countries. However, insufficient data are available on the chemical speciation of inorganic arsenicals in tropical paddy soils. Inorganic As-containing pesticides were used in tropical countries, a few decades ago, however, their fate have not been studied. Hence, the objective of this study was to determine fractionation of inorganic arsenicals and to assess As lability with/without fertilizer application using a static incubation experiment. Eight soils from wet and dry regions of Sri Lanka were amended with 1,000 mg/kg arsenate for this purpose. The FT-IR and XRF results suggested that soils in the wet region were rich in Fe/Al-oxides. Paddy soils in the dry zone showed high As lability. These low-humic gley soils have low Fe/Al oxyhydroxide and alkaline pH. In contrast, the wet zone had soils with higher As retention capacity, high amounts of Fe/Al oxyhydroxide, and acidic pH. Arsenic lability increased considerably 30 days after fertilizer application. Overall, As lability was mainly influenced by soil mineralogical and chemical properties, i.e., Fe/Al oxyhydroxide, pH, organic matter, and fertilizer application.",
Arsenic,1597342,"Arsenic Dissolution from Japanese Paddy Soil by a Dissimilatory Arsenate-Reducing Bacterium Geobacter sp. OR-1 Abstract: Dissimilatory As(V) (arsenate)-reducing bacteria may play an important role in arsenic release from anoxic sediments in the form of As(III) (arsenite). Although respiratory arsenate reductase genes (arrA) closely related to Geobacter species have been frequently detected in arsenic-rich sediments, it is still unclear whether they directly participate in arsenic release, mainly due to lack of pure cultures capable of arsenate reduction. In this study, we isolated a novel dissimilatory arsenate-reducing bacterium, strain OR-1, from Japanese paddy soil, and found that it was phylogenetically closely related to Geobacter pelophilus. OR-1 also utilized soluble Fe(III), ferrihydrite, nitrate, and fumarate as electron acceptors. OR-1 catalyzed dissolution of arsenic from arsenate-adsorbed ferrihydrite, while Geobacter metallireducens GS-15 did not. Furthermore, inoculation of washed cells of OR-1 into sterilized paddy soil successfully restored arsenic release. Arsenic K-edge X-ray absorption near-edge structure analysis revealed that strain OR-1 reduced arsenate directly on the soil solid phase. Analysis of putative ArrA sequences from paddy soils suggested that Geobacter-related bacteria, including those closely related to OR-1, play an important role in arsenic release from paddy soils. Our results provide direct evidence for arsenic dissolution by Geobacter species and support the hypothesis that Geobacter species play a significant role in reduction and mobilization of arsenic in flooded soils and anoxic sediments.",
Arsenic,2337071,"Soil geochemistry and groundwater contamination in an arsenic-affected area of the Datong Basin, China Abstract: This study describes the geochemistry of the topsoils from an arsenic (As)-affected area of the Datong Basin and identifies the possible sources and the enrichment mechanisms of As in groundwater. A total of 122 soil samples were collected from the study area. Analytical results indicate that soil As is higher than the average value of the Shanxi province topsoils. Fertilizer application and weathering of the bedrock both contributed to the presence of elements, including As, in the soil of the area. Furthermore, these elements may be strongly bound to Fe and Mn oxides/hydroxides. In addition, the depletion of K indicates that this element is readily leached into the groundwater rather than being retained in the soils. A groundwater area with high As levels corresponding spatially to soil samples with no As accumulation clearly shows the effects of irrigation or salt flushing on the soil compositions. Arsenic can be mobilized under reducing condition due to organic matter input or changes in redox conditions induced by irrigation or salt flushing and can be transported with vertically recharged water into shallow, unconfined aquifers, thus elevating the As concentration in groundwater.",
Arsenic,2149288,Quantitative determination of metal and metalloid spatial distribution in hydrated and fresh roots of cowpea using synchrotron-based X-ray fluorescence microscopy Abstract: ,
Arsenic,2345672,"34?Ethnic and Gender Differences in Symptom-to-Door Times in Patients Presenting with St Elevation Myocardial Infarction Abstract: 34 Table 1 Gender related differences Variable Gender (n = 1020) P value Male (n = 768) Female (n = 252) Median S-T-D-T (IQR) 113 (68-247) 132 (72-312) 0.066(*) In hospital death n (%) 33 (4) 27 (11) &lt;0.001 Age (mean±SD) 59 (13) 67 (14) &lt;0.001(**) Family history of CAD n (%) 255 (34) 65 (27) 0.039 Previous n (%)MICABGPCI 134 (17)24 (3)109 (14) 46 (18)7 (3)33 (13) 0.770.780.66 Diabetes n (%) 136 (18) 62 (25) 0.019 Ethnicity n (%)W-EA-CSA 530 (69)27 (4)211 (27) 189 (75)11 (4)52 (21) 0.092 Ventilation pre admission n (%) 29 (4) 4 (2) 0.088 Current smoking n (%) 327 (44) 77 (31) &lt;0.001 S-T-D-T Symptom-to-door-time, MI myocardial infarction, CABG coronary artery bypass grafting, PCI percutaneous coronary intervention, W-E White European, A-C Afro-Caribbean, SA South Asian. *Mann-Whitney U test, **Analysis of variance (ANOVA), all other p values derived from chi-squared test. heartjnl;100/Suppl_3/A18-a/T2T2T2 Abstract 34 Table 2 Characteristics of ethnic groups Variable Ethnicity (n = 1020) P value White-European(n = 719) Afro-Caribbean(n = 38) South Asian(n = 263) Median symptom to door time (IQR) (minutes) 115 (69-250) 147 (74-572) 124 (68-267) 0.37(***) Age, years 63 55 58 &lt;0.001(*) Male n (%) 530 (74) 27 (71) 211 (80) 0.09(**) Family history of CAD n (%) 217 (31) 12 (32) 91 (36) 0.34(**) Previous n (%)MICABGPCI 120 (17)21 (3)98 (14) 6 (16)0 (0)4 (11) 54 (21)10 (4)40 (15) 0.35(**) 0.42(**) 0.68(**) Diabetes n (%) 91 (13) 13 (34) 94 (36) &lt;0.001(**) Ventilation pre admission n (%) 22 (3) 1 (3) 10 (4) 0.82(**) Current smoking n (%) 314 (45) 16 (43) 74 (29) &lt;0.001(**) *Analysis of variance (ANOVA), **Chi-squared test, ***Kruskall-Wallis test.<br /><br /><strong>CONCLUSIONS: </strong>After adjusting for age and gender South Asians with STEMI present later following the onset of symptoms than other ethnic groups which may contribute to the higher in-hospital mortality seen in this group. There is no diff rence in symptom-to-door-time between men and women therefore this is unlikely to contribute to the observed sex difference in inpatient mortality.",
Arsenic,1020535,"Arsenic-induced NFkappaB transactivation through Erks- and JNKs-dependent pathways in mouse epidermal JB6 cells Abstract: Tumor promoting effects of arsenic are believed to be associated with its transactivation activity on transcription factors, such as AP-1 and NFkappaB. However, the results from different groups studying the effects of arsenic on NFkappaB activation are contradictory in different cell models. Since arsenic is a strong skin carcinogen, we have investigated the activation of NFkappaB by arsenic in a mouse skin epidermal cell line, JB6 cells. Exposure of cells to arsenite or arsenate led to NFkappaB transactivation in mouse epidermal JB6 NFkappaB-luciferase reporter stable transfectants, C141 NFkappaB mass1. This induction of NFkappaB activity by arsenic was dose- and time-dependent. The transactivation of NFkappaB by arsenic appeared to be through activation of Erks and JNKs pathways because increased NFkappaB activity by arsenic could be dramatically inhibited by either pre-treatment of cells with PD98059 or overexpression of dominant negative JNK1. That Erks activation is required for arsenic-induced NFkappaB transactivation was further supported by the findings that arsenic-induced NFkappaB transactivation was impaired in JB6 30.7b cells, which were deficient in Erks.",
Arsenic,627168,"Chronic arsenic exposure and urinary 8-hydroxy-2'-deoxyguanosine in an arsenic-affected area in Inner Mongolia, China Abstract: OBJECTIVE: Recent studies have shown that generation of reactive oxidants during arsenic metabolism can play an important role in arsenic-induced injury. The purpose of this study was to examine the relationship between arsenic in drinking water and oxidative stress in humans by measuring 8-Hydroxy-2'-deoxyguanosine (8-OHdG). METHODS: We performed a cross-sectional study in an arsenic-affected village in Hetao Plain, Inner Mongolia, China. A total of 134 of the 143 inhabitants (93.7%) of the village participated in the study. The levels of 8-OHdG, arsenic and its metabolites were measured in urine collected from the participants. Regression analyses were performed to investigate the relationship between arsenic species and 8-OHdG levels in urine. RESULTS: In the polluted village, monomethylarsenic was significantly higher in subjects with arsenic dermatosis than those without dermatosis despite no difference in mean levels of arsenic in well water between both types of subject. For subjects with arsenic dermatosis, arsenic species and metabolites in urine are significantly associated with 8-OHdG, while there was no statistically significant relationship for subjects without arsenic dermatosis. For all residents of the polluted village, the levels of dimethylarsenic and 8-OHdG were significantly higher for those who had been exposed to well water for more than 12 years. CONCLUSIONS: These results provide evidence of a link between exposure to arsenic from drinking water and oxidative stress, which may play an important role in arsenic-involved injuries.",
Arsenic,2088368,"Characterization of three soils in Hidalgo and Queretaro, Mexico: availability and toxic damage by arsenic in chickpea (Cicer arietinum L.) Abstract: ",
Arsenic,2345709,"Arsenic methylation capacity and developmental delay in preschool children in Taiwan Abstract: Environmental exposure to lead or mercury can cause neurodevelopmental damage. Arsenic is another neurotoxicant that can affect intellectual function in children. This study was designed to explore the difference of arsenic methylation capacity indices between with and without developmental delay in preschool children. We also aimed to identify whether blood levels of lead or mercury modify the effect of arsenic methylation capacity indices. A cross sectional study was conducted from August 2010 to March 2012. All participants recruited from the Shin Kong Wu Ho-Su Memorial Teaching Hospital. In all, 63 children with developmental delay and 35 children without developmental delay were recruited. Urinary arsenic species, including arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) were measured with a high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Lead and mercury levels of red blood cells were measured by inductively coupled mass spectrometry. All participants underwent developmental assessments to confirm developmental delays, including evaluations of gross motor, fine motor, speech-language, cognition, social, and emotional domains. Urinary total arsenic and MMA(V) percentage were significantly positively associated and DMA(V) percentage was negatively associated with the risk of developmental delay in a dose-dependent manner after adjustment for blood lead or mercury levels and other risk factors. A multivariate regression analysis indicated that blood lead level and arsenic methylation capacity each independently contributed to the risk of developmental delay. This is the first study to show that arsenic methylation capacity is associated with developmental delay, even without obvious environmental arsenic exposure.",
Arsenic,1019758,"Mustard oil and garlic extract as inhibitors of sodium arsenite-induced chromosomal breaks in vivo Abstract: Arsenic, a well-known human carcinogen present as a contaminant in ground water poses a serious threat to public health in various countries. The anticlastogenic properties of two dietary supplements, garlic and mustard oil, were screened against the clastogenic activity of sodium arsenite, since diet may contain factors which affect the process of mutagenesis and carcinogenesis. Aqueous extract of garlic (100 mg/kg b.w.) and mustard oil (0.643 mg/kg b.w.) were fed to Mus musculus for 30 consecutive days either singly or simultaneously. Sodium arsenite (0.1 mg/kg b.w.) was injected subcutaneously on days 7, 14, 21 and 30 of the experiment, singly and together with the dietary supplements. The animals were sacrificed 24 h after the last exposure to sodium arsenite and clastogenic effects were observed in the bone marrow cells. The degree of modulation of sodium arsenite-induced chromosomal aberrations was more pronounced in mustard oil than in garlic extract and simultaneous administration of both the dietary supplements reduced the clastogenic effects of sodium arsenite closer to the level of the negative control. The greater efficacy could be due to the interaction of the two dietary supplements and its radical scavenging property.",
Arsenic,629950,"Tumor promoter arsenite stimulates histone H3 phosphoacetylation of proto-oncogenes c-fos and c-jun chromatin in human diploid fibroblasts Abstract: Although epidemiological studies have long estab- Ushed that inorganic arsenic is a potent human carcin ogen, the underlying mechanisms are stiU poorly under stood. Recent studies suggest that inorganic arsenic may act as a tumor promoter by perturbing key signal ing transduction pathways. We have shown previously that arsenite can potently activate the mitogen-activated protein kinase cascades and induce the expres sion of proliferation-associated genes, including protooncogenes c-jun and c-fos. In order to elucidate further the molecular mechanisms underlying its tumor-pro moting properties, we investigated the signaling events involved in arsenite-mediated induction of c-fos and cjun. We found that induction of both c-fos and c-jun by arsenite can be substantially inhibited by the MEKselective inhibitor U0126, suggesting that the ERK pathway is criticaUy involved in their up-regulation. Interestingly, arsenite dramatically induced the phos phorylation and acetylation ofhistone H3 preceding the induction of mRNAs encoding c-fos and c-jun. Finally, chromatin immunoprecipitation assays revealed that arsenite treatment markedly induced the phosphorylation/ acetylation of histone H3 associated with the c-fos and cjun genes through an ERK-dependent pathway. Our results strongly suggest that arsenic-triggered al terations in chromatin structure perturb specific gene transcription, including that of proto-oncogenes c-jun and c-fos, and may thereby contribute to the carcino genic process.",
Arsenic,1017584,"A study of the subchronic effects of arsenic exposure on the liver tissues of Labeo rohita using Fourier transform infrared technique Abstract: In this work, an attempt has been made to study the subchronic effects of arsenic exposure on the biochemical composition; mainly proteins of the liver tissues of Labeo rohita fingerlings by using Fourier transform infrared (FT-IR) spectroscopic technique. The study was carried out using a Perkin Elmer-Spectrum Rx1 spectrometer. Because of arsenic exposure, significant reductions in the intensity as well as area of amide bands have been observed in the liver tissues. The decreased intensity of the amide bands could be interpreted as the result of alteration of the protein synthesis due to the high affinity of metal compounds towards different amino acid residues of proteins. Further, meso-2, 3-dimercaptosuccinic acid (DMSA) treatment shows the recovery of the protein content in the liver tissues. To confirm that the changes observed are only due to the bio-accumulation of arsenic, the concentration of arsenic in the liver tissues of Labeo rohita was determined by using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). It is observed that the arsenic level in the control tissues is found to be below detectable limit, whereas the arsenic exposed liver shows an accumulation of 66.68 ± 0.43 ?g/g and DMSA treatment reduces the arsenic content to 17.96 ± 0.19 ?g/g. In conclusion, this study gives clear evidence that the use of FT-IR spectroscopy is a powerful approach to achieve more insight into the protein alterations caused by arsenic.",
Arsenic,1347244,"A shot in the rear, not a shot in the dark: application of a mass clinic framework in a public health emergency Abstract: An outbreak of foodborne hepatitis A infection compelled two regional health departments in eastern Tennessee to implement an emergency mass clinic for providing hepatitis immune serum globulin (ISG) to several thousand potentially exposed people. For the mass clinic framework, we utilized the smallpox post-event clinic plans of the Centers for Disease Control and Prevention (CDC), although the plans had only been exercised for smallpox. Following CDC's guidelines for staffing and organizing the mass clinic, we provided 5,038 doses of ISG during a total of 24 hours of clinic operation, using 3,467 person-hours, or 1.45 ISG doses per person-hour-very close to the 1.58 doses per person-hour targeted in CDC's smallpox post-event clinic plans. The mass clinic showed that CDC's smallpox post-event clinic guidelines were feasible, practical, and adaptable to other mass clinic situations.",
Arsenic,1020756,"The potential biological mechanisms of arsenic-induced diabetes mellitus Abstract: Although epidemiologic studies carried out in Taiwan, Bangladesh, and Sweden have demonstrated a diabetogenic effect of arsenic, the mechanisms remain unclear and require further investigation. This paper reviewed the potential biological mechanisms of arsenic-induced diabetes mellitus based on the current knowledge of the biochemical properties of arsenic. Arsenate can substitute phosphate in the formation of adenosine triphosphate (ATP) and other phosphate intermediates involved in glucose metabolism, which could theoretically slow down the normal metabolism of glucose, interrupt the production of energy, and interfere with the ATP-dependent insulin secretion. However, the concentration of arsenate required for such reaction is high and not physiologically relevant, and these effects may only happen in acute intoxication and may not be effective in subjects chronically exposed to low-dose arsenic. On the other hand, arsenite has high affinity for sulfhydryl groups and thus can form covalent bonds with the disulfide bridges in the molecules of insulin, insulin receptors, glucose transporters (GLUTs), and enzymes involved in glucose metabolism (e.g., pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase). As a result, the normal functions of these molecules can be hampered. However, a direct effect on these molecules caused by arsenite at physiologically relevant concentrations seems unlikely. Recent evidence has shown that treatment of arsenite at lower and physiologically relevant concentrations can stimulate glucose transport, in contrary to an inhibitory effect exerted by phenylarsine oxide (PAO) or by higher doses of arsenite. Induction of oxidative stress and interferences in signal transduction or gene expression by arsenic or by its methylated metabolites are the most possible causes to arsenic-induced diabetes mellitus through mechanisms of induction of insulin resistance and beta cell dysfunction. Recent studies have shown that, in subjects with chronic arsenic exposure, oxidative stress is increased and the expression of tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) is upregulated. Both of these two cytokines have been well known for their effect on the induction of insulin resistance. Arsenite at physiologically relevant concentration also shows inhibitory effect on the expression of peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear hormone receptor important for activating insulin action. Oxidative stress has been suggested as a major pathogenic link to both insulin resistance and beta cell dysfunction through mechanisms involving activation of nuclear factor-kappaB (NF-kappaB), which is also activated by low levels of arsenic. Although without supportive data, superoxide production induced by arsenic exposure can theoretically impair insulin secretion by interaction with uncoupling protein 2 (UCP2), and oxidative stress can also cause amyloid formation in the pancreas, which could progressively destroy the insulin-secreting beta cells. Individual susceptibility with respect to genetics, nutritional status, health status, detoxification capability, interactions with other trace elements, and the existence of other well-recognized risk factors of diabetes mellitus can influence the toxicity of arsenic on organs involved in glucose metabolism and determine the progression of insulin resistance and impaired insulin secretion to a status of persistent hyperglycemia or diabetes mellitus. In conclusions, insulin resistance and beta cell dysfunction can be induced by chronic arsenic exposure. These defects may be responsible for arsenic-induced diabetes mellitus, but investigations are required to test this hypothesis.",
Arsenic,1353101,"Role of Quaternary stratigraphy on arsenic-contaminated groundwater from parts of Barak Valley, Assam, North-East India Abstract: ",
Arsenic,2088309,"Adsorption of As(III), As(V) and dimethylarsinic acid onto synthesized lepidocrocite Abstract: The trapping of arsenic by zero valent iron is strongly dependant on iron by-products. Among these, lepidocrite has been scarcely studied. In this work, we studied the adsorption of two inorganic (As(III), As(V)) and one organic (dimethylarsinic acid, DMA) arsenic species onto lepidocrocite. pH influence was considered in the range 5 to 9, which corresponds to natural water pH. Langmuir model was used to simulate As adsorption isotherms. Our results showed that lepidocrocite offers high adsorption capacities: up to 0,25, 0,41 and 1 mol for As(V), DMA and As(III) could be respectively trapped per kilogram of zero-valent iron. pH influence varied from one arsenic species to another: increasing pH improve As(III) and DMA sorption whereas it has a very low effect on As(V) sorption.",
Arsenic,1797802,"High arsenic in rice is associated with elevated genotoxic effects in humans Abstract: Arsenic in drinking water may cause major deleterious health impacts including death. Although arsenic in rice has recently been demonstrated to be a potential exposure route for humans, there has been to date no direct evidence for the impact of such exposure on human health. Here we show for the first time, through a cohort study in West Bengal, India, involving over 400 human subjects not otherwise significantly exposed to arsenic through drinking water, elevated genotoxic effects, as measured by micronuclei (MN) in urothelial cells, associated with the staple consumption of cooked rice with >200??g/kg arsenic. Further work is required to determine the applicability to populations with different dietary and genetic characteristics, but with over 3 billion people in the world consuming rice as a staple food and several percent of this rice containing such elevated arsenic concentrations, this study raises considerable concerns over the threat to human health.",
Arsenic,1070498,"Cancer incidence and soil arsenic exposure in a historical gold mining area in Victoria, Australia: A geospatial analysis Abstract: Soil and mine waste around historical gold mining sites may have elevated arsenic concentrations. Recent evidence suggests some systemic arsenic absorption by residents in the goldfields region of Victoria, Australia. Victorian Cancer Registry and geochemical data were accessed for an ecological geographical correlation study, 1984-2003. Spatial empirical Bayes smoothing was applied when estimating standardised incidence ratios (SIRs) for cancers in 61 statistical local areas. The derived soil arsenic exposure metric ranged from 1.4 to 1857?mg/kg. Spatial autoregressive modelling detected increases in smoothed SIRs for all cancers of 0.05 (95% confidence interval (CI), 0.02-0.08) and 0.04 (0.01-0.07) per 2.7-fold increase in the natural log-transformed exposure metric for males and females, respectively, in more socioeconomically disadvantaged areas; for melanoma in males (0.05 (0.01-0.08) adjusted for disadvantage) and females (0.05 (0.02-0.09) in disadvantaged areas). Excess risks were estimated for all cancers (relative risk 1.21 (95% CI, 1.15-1.27) and 1.08 (1.03-1.14)), and melanoma (1.52 (1.25-1.85) and 1.29 (1.08-1.55)), for males and females, respectively, in disadvantaged areas in the highest quintile of the exposure metric relative to the lowest. Our findings suggest small but significant increases in past cancer risk associated with increasing soil arsenic in socioeconomically disadvantaged areas and demonstrate the robustness of this geospatial approach.",
Arsenic,1017306,"BioMetals: a historical and personal perspective Abstract: Understanding of BioMetals developed basically from a starting point about 60 years ago to current mechanistic understanding of the biological behavior of many metal ions from protein structural and functional studies. Figure 1 shows a Biochemical Periodic Table, element by element, with requirements, roles and biochemistry of the specific ions indicated. With few exceptions, the biology is of the ions formed and not of the elemental state of each. Early BioMetals efforts defined nutritional growth needs for animals, plants and microbes for inorganic &quot;macro-nutrients&quot; such as magnesium, calcium, potassium, sodium, and phosphate and of &quot;micronutrients&quot; such as copper, iron, manganese and zinc. Surprises came early with regard to microbes, for example the finding that Escherichia coli (then and now the standard microbial model) grows happily in the apparent total absence of calcium, sodium, and chloride, which are certainly major animal nutrients. Some elements such as mercury and arsenic are never required by living cells, but are always toxic, often at very low levels. Therefore, the division into nutrient elements and toxic elements came soon. For most inorganic nutrients, excessive amounts can be toxic as well, for example for copper and iron.",
Arsenic,1357354,"Determination and Speciation of Arsenic in Human Urine by Ion-Exchange Chromatographylow Injection Analysis with Hydride Generation/Atomic Absorption Spectroscopy Abstract: A simple analytical method for the determination of total arsenic (7440382) and for the speciation of various arsenic metabolites using ion exchange chromatography/flow injection analysis with hydride generation/atomic absorption spectroscopy (IEC-HG) was developed. Total arsenic determination and arsenic speciation in urine was performed using a flow injection hydride generating IEC-HG/AAS at 197.7 nanometers. Urine was digested with nitric-acid, heated to 115 degrees-C, mixed with sulfuric-acid, and heated to 130 degrees-C. The solution was heated again, cooled, and mixed with hydrogen-peroxide. The mixture was maintained at 180 degrees-C and evaporated. Arsenic was determined by IEC-HG/AAS from this solution. Alternatively, samples were separated in a AG50, WX8 resin column to separate metabolic forms of arsenic, followed by IEC-HG/AAS analysis of a 2 milliliter sample. The results indicated that total arsenic could be detected up to 3 parts per billion, while each arsenic form could be detected up to 2 parts per billion. Recoveries were 93%, 91%, and 85% for inorganic arsenic, monomethyl-arsenic-acid, and dimethyl-arsenic-acid, respectively. The relative standard deviation varied from 3.2 to 4.6%. The authors conclude that this method could be used for monitoring occupational exposure to arsenic.",
Arsenic,2343544,"Geothermal spring causes arsenic contamination in river waters of the southern Tibetan Plateau, China Abstract: Large numbers of As-enriched geothermal springs are distributed at the southern Tibetan Plateau, and their influence on river water is still not clear. Lhasa River and its tributary, Duilong Qu located at downstream of the largest geothermal spring of the Tibetan Plateau, were selected for sampling during monsoon and non-monsoon seasons. Dissolved trace elements (B, Cr, Ni, Cu, Zn, As, Cs, Ba and U) were measured in river water samples by ICP-MS. The results show that due to contribution of geothermal spring, As levels of Duilong Qu (205.6 mu g/L) and Lhasa River (12.7 mu g/L) were higher during non-monsoon season than that of WHO guideline for drinking water (10 mu g/L). Accordingly, As level of river water was lower during the monsoon season than that of the non-monsoon season due mainly to dilution process. Therefore, although Tibetan rivers are generally considered as free of contamination, geothermal springs cause As contamination of river water at some local regions and may harm the local residents. Further research is needed in other parts of the plateau to determine whether As level of groundwater of the related region is high.",
Arsenic,2337243,"Source of arsenic-bearing pyrite in southwestern Vermont, USA: Sulfur isotope evidence Abstract: Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite ?(34)S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to &gt;2000ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from -5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in (34)S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between ?(34)S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy ?(34)S values.",
Arsenic,1030806,"Antioxidant activity of different extracts of Argentinian medicinal plants against arsenic-induced toxicity in renal cells Abstract: Chronic toxicity of arsenic resulting from drinking water is a health problem encountered in humans, especially in South America and Asia, where a correlation between oxidative stress, tumor promotion, and arsenic exposure has been observed. Differential solvent extraction (petroleum ether (PE); dichloromethane (DCM); methanol (OL) and water (W)) was performed to compare the protective (antioxidant) activity of five Argentinian medicinal plants on arsenite-induced oxidative stress in Vero cells, assayed by hydroperoxide measurement. The results were analyzed using ANOVA followed by the LSD Fisher test. The data showed that arsenite was a pro-oxidant agent which acts in a time-dose-dependent manner. Extracts from Eupatorium buniifolium (PE), Lantana grisebachii (PE, W), Mandevilla pentlandiana (PE, W), and Sebastiania commersoniana (DCM, OL, W) prevented the formation of both aqueous and lipid hydroperoxides, but Heterothalamus alienus only impeded lipid ones. Therefore, antioxidant extracts are potentially beneficial and may have a protective activity against arsenite-induced renal injury. Among these, the aqueous extract of L. grisebachii may represent the most suitable preparation for humans since the traditional usage of this plant in popular medicine is through consumption of tea.",1
Arsenic,1508543,"Protective effect of conjugated linolenic acid isomers present in vegetable oils against arsenite-induced renal toxicity in rat model Abstract: OBJECTIVE: The aim of the present study was to investigate the protective effect of conjugated linolenic acid (CLnA), present in vegetable oils against arsenite-induced renal oxidative stress. METHODS: Albino rats were divided into six groups. Group 1 was control and group 2 was treated with sodium arsenite (Sa; 10 mg/kg BW). Rats in groups 3 and 4 were treated with mixture of ?-eleostearic acid and punicic acid (1:1) (0.5% and 1.0%, respectively), whereas rats in the groups 5 and 6 were treated with 0.5% of ?-eleostearic acid and 0.5% of punicic acid, respectively, along with Sa by oral gavage once daily. RESULTS: Results revealed that activity of antioxidant enzymes and total reduced glutathione content, total protein content, and phospholipid content in kidney were decreased significantly in arsenite-treated group compared with control. Activity of nitric oxide synthase, peroxidation of lipid, protein oxidation, total cholesterol content, total lipid content of kidney, and plasma creatinine level were increased significantly (P &lt; 0.05) in arsenite-treated rats compared with control. Fatty-acid composition of renal lipids showed significant decrease in monounsaturated fatty acid, polyunsaturated fatty acid (PUFA) content, and increase in saturated fatty acid content due to oxidative stress. PUFA such as ?-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid decreased significantly with significant (P &lt; 0.05) increase in arachidonic acid content after Sa treatment. Administration of blended product of both the isomers caused better restoration of renal fatty acids and other altered parameters. CONCLUSION: CLnA isomers caused amelioration of renal oxidative stress and the isomers showed synergistic activity.",
Arsenic,627868,"Arsenic-induced toxicity and the protective role of ascorbic acid in mouse testis Abstract: Oxidative stress has been suggested to be a major cause of male reproductive failure. Here, we investigated whether arsenic, which impairs male reproductive functions in rodent models, acts by inducing oxidative stress. Male 8-week-old ICR mice were given drinking water containing 20 or 40 mg/l sodium arsenite with or without 0.75 or 1.5 g/l of the antioxidant ascorbic acid for 5 weeks. The arsenic-treated mice showed decreased epididymidal sperm counts and testicular weights compared to untreated mice. These effects were reversed in mice that were co-treated with ascorbic acid. Similarly, arsenic treatment lowered the activities of testicular 3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD, which play important roles in steroidogenesis, and this was reversed by co-treatment with ascorbic acid. The testicles of arsenic-treated mice had decreased glutathione (GSH) levels (which correlate inversely with the degree of cellular oxidative stress) and elevated levels of protein carbonyl (a marker of oxidative damage to tissue proteins). Ascorbic acid co-treatment reversed both of these effects. Thus, ascorbic acid blocks both the adverse effects of arsenic on male reproductive functions and the arsenic-induced testicular oxidative changes. These observations support the notion that arsenic impairs male reproductive function by inducing oxidative stress.",
Arsenic,628659,"Differential effect of sodium arsenite during the activation of human CD4+ and CD8+ T lymphocytes Abstract: Contamination of water with arsenic is a problem affecting several regions of the world. Peripheral blood mononuclear cells (PBMC) from chronically exposed individuals show a lower replicating activity than non-exposed individuals when stimulated with phytohemagglutinin (PHA). We have previously reported that PBMC from healthy donors treated in vitro with 1 ?M sodium arsenite (NaAsO2) and stimulated with PHA showed a reduction in proliferation by a delay in cell cycle entry and a decrease in the rounds of cell division. In this paper we tested the effect of 1–5 ?M NaAsO2 on the proliferation, viability, blast transformation, expression of the CD4 and CD8 molecules, and during the activation and proliferation of both CD4+ and CD8+ T lymphocytes. We found a reduction in cell proliferation and an increase in non-dividing cells with higher concentrations of NaAsO2 (2–5 ?M) when proliferation was studied by 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution. The use of 7-aminoactinomycin D (7-AAD) in CFSE-labeled cells allowed us to detect an increase in percentage of non-dividing cells, and an increase in apoptotic/dead cells mainly in non-proliferating cells. Analysis of the expression of CD4 and CD8 molecules on these cells showed that concentrations ? 2 ?M NaAsO2 reduced the expression of the CD8 molecule and induced apoptosis/death in CD4+ cells. Analysis of blast transformation by flow cytometry showed an accumulation of CD8+ resting cells in the presence of NaAsO2. Analysis of CD25 and CD69 expression in kinetics experiments in both subtypes showed a delay in the expression of CD25 and a delay in the downregulation of the CD69 molecule, in both CD4+ and CD8+ cells. However, in the case of CD8+ cells, we detected an accumulation of a CD25?CD69? population in the presence of increasing concentrations of NaAsO2. Altogether, our results show that NaAsO2 alters the expression kinetics of the early activation molecules CD25 and CD69 similarly in both subtypes. In addition, activated and non-activated CD4+ cells die by apoptotic mechanisms and although a percentage of CD8+ cells also die by apoptosis, a subpopulation of these cells is unable to activate and thus accumulates as resting cells.",
Arsenic,1379433,"Health Issues in the Microelectronics Industry Abstract: This report discusses health considerations in the microelectronics industry. Early health concerns in this industry centered around the manufacture of semiconductors with the inherent exposures to arsenic (7778394) and other metals. Skin rashes appeared from working with epoxy resins. Hydrofluoric-acid (7664393) burns became apparent as the industry grew. Changes in etching method replaced the wet etching with dry plasma etching using as its energy source radiofrequency (RF) power. The health consequences of RF exposures were not known at that time. More advanced technology demands have made it necessary to implant ions of arsenic, phosphorus (7723140), and boron (7440428) harvested from the toxic arsine (7784421), phosphine (7803512) and diborane (19287457) gases. The exposures to dusts, hazardous chemicals, ionizing and nonionizing radiation, ergonomic and psychologic stressors, and various other hazards such as explosion, fire, and electrocution, makes the microelectronics industry workers subject to various occupational illnesses and dangers. The author urges health and safety professionals throughout the world to become more familiar with the hazards in the major industry, and suggests remedial measures to be taken in the workplace to limit the hazards to the workers.",
Arsenic,2343534,"Diuron-induced rat urinary bladder carcinogenesis: Mode of action and human relevance evaluations using the International Programme on Chemical Safety framework Abstract: Diuron, a high volume substituted urea herbicide, induced high incidences of urinary bladder carcinomas and low incidences of kidney pelvis papillomas and carcinomas in rats exposed to high doses (2500 ppm) in a 2-year bioassay. Diuron is registered for both occupational and residential uses and is used worldwide for more than 30 different crops. The proposed rat urothelial mode of action (MOA) for this herbicide consists of metabolic activation to metabolites that are excreted and concentrated in the urine, leading to cytotoxicity, urothelial cell necrosis and exfoliation, regenerative hyperplasia, and eventually tumors. We show evidence for this MOA for diuron using the International Programme on Chemical Safety (IPCS) conceptual framework for evaluating an MOA for chemical carcinogens, and the United States Environmental Protection Agency (USEPA) and IPCS framework for assessing human relevance.",
Arsenic,1519039,"Reduction of arsenite-enhanced ultraviolet radiation-induced DNA damage by supplemental zinc Abstract: Arsenic is a recognized human carcinogen and there is evidence that arsenic augments the carcinogenicity of DNA damaging agents such as ultraviolet radiation (UVR) thereby acting as a co-carcinogen. Inhibition of DNA repair is one proposed mechanism to account for the co-carcinogenic actions of arsenic. We and others find that arsenite interferes with the function of certain zinc finger DNA repair proteins. Furthermore, we reported that zinc reverses the effects of arsenite in cultured cells and a DNA repair target protein, poly (ADP-ribose) polymerase-1. In order to determine whether zinc ameliorates the effects of arsenite on UVR-induced DNA damage in human keratinocytes and in an in vivo model, normal human epidermal keratinocytes and SKH-1 hairless mice were exposed to arsenite, zinc or both before solar-simulated (ss) UVR exposure. Poly (ADP-ribose) polymerase activity, DNA damage and mutation frequencies at the Hprt locus were measured in each treatment group in normal human keratinocytes. DNA damage was assessed in vivo by immunohistochemical staining of skin sections isolated from SKH-1 hairless mice. Cell-based findings demonstrate that ssUVR-induced DNA damage and mutagenesis are enhanced by arsenite, and supplemental zinc partially reverses the arsenite effect. In vivo studies confirm that zinc supplementation decreases arsenite-enhanced DNA damage in response to ssUVR exposure. From these data we can conclude that zinc offsets the impact of arsenic on ssUVR-stimulated DNA damage in cells and in vivo suggesting that zinc supplementation may provide a strategy to improve DNA repair capacity in arsenic exposed human populations.",
Arsenic,8630,"The concentration and chemical status of arsenic in the early placentas of arsenate-dosed hamsters Abstract: We determined the concentration and chemical status of arsenic in the placentas of hamsters following continuous exposure via the osmotic minipump to minimally and frankly teratogenic doses of arsenate. Close to 70% of the placental arsenic is bound to macromolecules, two-thirds of which is dialyzable. The remaining 30% of arsenic consists of low molecular weight species, predominantly inorganic arsenic. This mix is the same for minimally teratogenic and frankly teratogenic doses of arsenate.",
Arsenic,1019155,"Chronic toxicity of arsenic in goats: clinicobiochemical changes, pathomorphology and tissue residues Abstract: Chronic inorganic arsenic toxicity was induced in goats by oral administration of one-fifth of the acute lethal dose 50 (ALD(50)) of sodium arsenite (25mgkg(-1) body weight) packed in gelatin capsules and given daily for 12 weeks. Clinical signs of toxicity developed from 3 week post-exposure, consisting of gastrointestinal disturbances and renal insufficiency with 100% mortality in all animals. There were significant (p&lt;0.01) decreases in total serum protein and the albumin: globulin ratio, and increases in blood glucose and various enzymatic activities of treated animals. Toxicity also induced severe pathomorphological changes, indicative of haemorrhagic and degenerative and/or necrotic lesions in most organs. In addition, proliferative pneumonia in lungs, hyperplastic goitre in thyroid and chronic proliferative lesions in skin were observed. Liver contained the largest residues of arsenic, followed by intestine, kidneys, thyroid, abomasum, spleen, skin, lungs and lowest in brain. The intensity of pathomorphological changes was proportional to the accumulated amount of arsenic in tissues/organs.",
Arsenic,1797798,"Cytotoxicity and gene expression changes induced by inorganic and organic trivalent arsenicals in human cells Abstract: Inorganic arsenic (iAs) is a human urinary bladder, skin and lung carcinogen. iAs is metabolized to methylated arsenicals, with trivalent arsenicals more cytotoxic than pentavalent forms in vitro. In this study, cytotoxicity and gene expression changes for arsenite (iAs(III)), monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)) were evaluated in three human cell types, urothelial (1T1), keratinocyte (HEK001) and bronchial epithelial (HBE) cells, corresponding to target organs for iAs-induced cancer. Cells were exposed to arsenicals to determine cytotoxicity and to study gene expression changes. Affymetrix chips were used to determine differentially expressed genes (DEGs) by statistical analysis. Lethal concentrations (LC50) for trivalent arsenicals in all cells ranged from 1.6 to 10?M. MMA(III) and DMA(III) had 4-12-fold greater potency compared to iAs. Increasing concentrations of iAs(III) induced more genes and additional signaling pathways in HBE cells. At equivalent cytotoxic concentrations, greater numbers of DEGs were induced in 1T1 cells compared to the other cells. Each arsenical altered slightly different signaling pathways within and between cell types, but when altered pathways from all three arsenicals were combined, they were similar between cell types. The major signaling pathways altered included NRF2-mediated stress response, interferon, p53, cell cycle regulation and lipid peroxidation. These results show a similar process qualitatively and quantitatively for all three cell types, and support a mode of action involving cytotoxicity and regenerative proliferation.",
Arsenic,1936142,"Function of arsATorf7orf8 of Bacillus sp. CDB3 in arsenic resistance Abstract: Bacillus sp. CDB3 isolated from an arsenic contaminated cattle dip site possesses an uncommon arsenic resistance (ars) operon bearing eight genes in the order of arsRYCDATorf7orf8. We investigated the functions of arsA, arsT, orf7 and orf8 in arsenic resistance using a plasmid-based gene knockout approach in the ars gene deficient Escherichia coli strain AW3110. The CDB3 arsA gene was shown to play a significant role in resistance, suggesting that the encoded ArsA may couple with the arsenite transporter, forming an ArsAY complex that can enhance arsenite extrusion efficiency. The disruption of either arsT or orf7 was not observed to affect arsenic resistance in the heterologous E. coli host, but their involvement in arsenic resistance can not be excluded. The orf8 gene is predicted to encode a putative dual-specificity protein phosphatase which also shares certain homology to arsenate reductases. The function loss of orf8 resulted in a remarkable decrease in resistance to arsenate, though not arsenite. To examine if this effect was due to the reduction of arsenate by orf8, the arsC gene within the 8-gene operon was disrupted. The resulting abolishment of arsenate resistance suggests that the involvement of orf8 in arsenic resistance is not via reductase activity.",
Arsenic,1508613,"Purification and characterization of glucose 6-phosphate dehydrogenase enzyme from rainbow trout (Oncorhynchus mykiss) liver and investigation of the effects of some metal ions on enzyme activity Abstract: Glucose 6-phosphate dehydrogenase (d-glucose 6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49; G6PD) is a key enzyme that is localized in all mammal tissues, especially in cytoplasmic sections and that catalyzes the first step of pentose phosphate metabolic pathway. In this study, G6PD enzyme was purified 1444-fold with a yield of 77% from rainbow trout liver using 2?,5?-ADP-sepharose-4B affinity chromatography. Moreover, a purity check of the enzyme was performed with sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Some characteristic features like optimal pH, stable pH, optimal temperature and optimal ionic strength were determined for the purified enzyme. In addition to this, in vitro effects of ions like silver nitrate (Ag+), thallium sulphate (TI+), cobalt (II) nitrate (Co2+) and arsenic (V) oxide (As5+) on enzyme activity were researched. Half-maximal inhibitory concentration (IC50) values of Ag+, Co2+ and As5+ metal ions, which showed an inhibitory effect, were found to be 0.0044, 0.084 and 4.058 mM, respectively; and their inhibition constants (Ki) were found to be 0.0052 ± 0.00042, 0.087 ± 0.015700 and 4.833 ± 1.753207 mM, respectively. Tl+ not exhibited inhibitory effect on the enzyme activity.",
Arsenic,2278398,"Water-soluble cationic cellulose coupled to a ultrafiltration membrane for the removal of arsenic and chromium Abstract: This article describes the retention properties of arsenic (V) and chromium (VI) using a water-soluble polymer based on cationic hydroxyethylcellulose and combined with an ultrafiltration membrane. The polymer was purchased commercially and was characterized by Fourier transform infrared spectroscopy (FTIR). The study of polymer removal capacity of As(V) and Cr(VI) were performed by liquid-phase polymer-based retention technique (LPR). By means of a washing method studied retention as a function of pH, the amount of polymer, and the concentration of As(V) and Cr(VI). The results showed that the retention capacity of both oxy-anions increases with the solution pH. Due to the presence of quaternary ammonium groups in the polymer structure, the retention of As(V) and Cr(VI) was higher at a pH of 9 than that at acidic pH levels, reaching values of 65% for Cr(VI) and 43% for As(V). The study in function of amount of polymer showed that using 75 mg the retention of As(V) was 65%. In the case of Cr(VI) using 50 mg of polymer, 67% retention was obtained. Using low concentrations for arsenic and chromium, maximum retention was found at 65% and 95%, respectively. The maximum retention capacity (MRC) of the polymer was determined by adding As(V) and Cr(VI) to the polymer solution and concentrating in successive steps. FTIR spectra before and after of retention showed differences by the interaction with oxy-anions.",
Arsenic,2278978,"Chemical generation of arsane and methylarsanes with amine boranes. Potentialities for nonchromatographic speciation of arsenic Abstract: The efficiency of chemical generation of arsanes from inorganic arsenic, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA), to arsane, AsH3, monomethylarsane, CH3AsH2 (MMA), and dimethylarsane, (CH3)2AsH (DMA), has been investigated in different reaction media with the aim to better elucidate the mechanisms controlling their generation process and to find the experimental conditions to implement a nonchromatographic arsenic speciation analytical method, which is based on the selective determination of some arsenic species. Studies were performed by continuous flow hydride generation coupled with atomic spectrometry (CF-HG-AS), using different reductants such as borane-ammonia (AB), borane-tert-butylamine (TBAB), and sodium tetrahydridoborate (THB) in HCl and HClO4 media, in the presence or absence of L-cysteine (Cys). The efficiency of HG processes for MMA and DMA is mainly controlled by the reactivity of the substrates with the borane, which could be strongly influenced by the formation of ion couples. The protonation of arsane did not play a significant role in the employed reaction system. By taking advantage of the different reactivity pattern of As species in selected generation conditions, DMAA and MMAA could be selectively determined in 0.5 and 10 M HClO4 solutions, respectively, in the presence of Cys, with AB as the reducing agent. The presence of Cys as a masking agent and the peculiar reducing properties of AB ensured a good control of interferences, as far as it has been observed for Co(II), Ni(II), Cu(II), Fe(II), Fe(III). The overall time needed to complete the prereduction step has been verified for MMAA and DMAA at different acidities in order to achieve the best selectivity. The selective determination of DMAA with AB/Cys in HClO4 has been optimized and applied to certified reference materials (CRMs) of natural waters CASS-4, SLRS-4, and NASS-4 (NRCC). The estimation of DMAA concentration allows us to correct the concentration of As(III) for the interference of DMAA in the selective determination of As(III) according to a selective HG method recently reported.",
Arsenic,1024580,"Volatile arsenic species released from Escherichia coli expressing the AsIII S-adenosylmethionine methyltransferase gene Abstract: Biological systems, ranging from bacteria and fungi to humans, can methylate arsenic. Recent studies have suggested that the AsIII S-adenosylmethionine methyltransferase (arsM) gene in bacteria was responsible for the removal of arsenic as the volatile arsines from the bacteria. However, there has been no direct measure of the arsines released from bacteria cultures. We describe here an integrated system incorporating the bacterial incubation and volatile arsenic species analysis, and we demonstrate its application to the identification of the volatile arsines produced in bacterial cultures. The headspace of the bacterial cultures was purged with helium, and the volatile arsenic species were trapped in a chromatographic column immersed in liquid nitrogen. The cryogenically trapped arsines [AsH3, (CH3)AsH2, (CH3)2AsH, and (CH3)3As] were separated by gas chromatography and were detected by inductively coupled plasma mass spectrometry. A hydride generation system was coupled to the bacterial culture system, allowing for spiking standards and for generating calibration arsines necessary for quantitative analysis. Both bacteria containing the arsM gene or its variant arsMC2 gene were able to produce 400-500 ng of trimethylarsine. No trimethylarsine was detectable in bacteria lacking the arsM gene (containing the vector plasmid as negative control). These results confirm that arsM is responsible for releasing arsenic as volatile species from the arsenic-resistant bacteria. Our results also show traces of AsH3, CH3AsH2, and (CH3)2AsH in cultures of bacteria expressing arsM. The method detection limits for AsH3, CH3AsH2, (CH3)2AsH, and (CH3)3As were 0.5, 0.5, 0.7, and 0.6 pg, respectively. The ability to quantify trace levels of these volatile arsenic species makes it possible to study the biotransformation and biochemical roles of the evolution of these volatile arsenic species by biological systems.",
Arsenic,628591,"Well water arsenic exposure, arsenic induced skin-lesions and self-reported morbidity in Inner Mongolia Abstract: Residents of the Bayingnormen region of Inner Mongolia have been exposed to arsenic-contaminated well water for over 20 years, but relatively few studies have investigated health effects in this region. We surveyed one village to document exposure to arsenic and assess the prevalence of arsenic-associated skin lesions and self-reported morbidity. Five-percent (632) of the 12,334 residents surveyed had skin lesions characteristics of arsenic exposure. Skin lesions were strongly associated with well water arsenic and there was an elevated prevalence among residents with water arsenic exposures as low as 5 microg/L-10 microg/L. The presence of skin lesions was also associated with self-reported cardiovascular disease.",
Arsenic,627236,"Arsenic-induced dysfunction in relaxation of blood vessels Abstract: Several epidemiological studies have suggested that exposure to arsenic is strongly correlated with the development of cardiovascular diseases such as hypertension. To determine whether arsenic affects vasomotor tone in blood vessels, we investigated the effect of arsenic on vasorelaxation using isolated rat aortic rings in an organ-bath system. Treatment with arsenite inhibited acetylcholine-induced relaxation of the aortic rings in a concentration-dependent manner, whereas several other arsenic species did not have any effect. Consistent with these findings, the levels of guanosine 3',5'-cyclic monophosphate (cGMP) in the aortic rings were significantly reduced by arsenite treatment. In cultured human aortic endothelial cells, treatment with arsenite resulted in a concentration-dependent inhibition of endothelial nitric oxide synthase (eNOS). In addition, higher concentrations of arsenite decreased the relaxation induced by sodium nitroprusside (an NO donor) and 8-Br-cGMP (a cGMP analog) in aortic rings without endothelium. These in vitro results indicate that arsenite is capable of suppressing relaxation in blood vessels by inhibiting eNOS activity in endothelial cells and by impairing the relaxation machinery in smooth muscle cells. In vivo studies revealed that the reduction of blood pressure by acetylcholine infusion was significantly suppressed after arsenite was administered intravenously to rats. These data suggest that an impairment of vasomotor tone due to arsenite exposure may be a contributing factor in the development of cardiovascular disease.",
Arsenic,628525,"Low level arsenic promotes progressive inflammatory angiogenesis and liver blood vessel remodeling in mice Abstract: The vascular effects of arsenic in drinking water are global health concerns contributing to human disease worldwide. Arsenic targets the endothelial cells lining blood vessels, and endothelial cell activation or dysfunction may underlie the pathogenesis of both arsenic-induced vascular diseases and arsenic-enhanced tumorigenesis. The purpose of the current studies was to demonstrate that exposing mice to drinking water containing environmentally relevant levels of arsenic promoted endothelial cell dysfunction and pathologic vascular remodeling. Increased angiogenesis, neovascularization, and inflammatory cell infiltration were observed in Matrigel plugs implanted in C57BL/6 mice following 5-week exposures to 5–500 ppb arsenic [Soucy, N.V., Mayka, D., Klei, L.R., Nemec, A.A., Bauer, J.A., Barchowsky, A., 2005. Neovascularization and angiogenic gene expression following chronic arsenic exposure in mice. Cardiovasc.Toxicol 5, 29–42]. Therefore, functional in vivo effects of arsenic on endothelial cell function and vessel remodeling in an endogenous vascular bed were investigated in the liver. Liver sinusoidal endothelial cells (LSEC) became progressively defenestrated and underwent capillarization to decrease vessel porosity following exposure to 250 ppb arsenic for 2 weeks. Sinusoidal expression of PECAM-1 and laminin-1 proteins, a hallmark of capillarization, was also increased by 2 weeks of exposure. LSEC caveolin-1 protein and caveolae expression were induced after 2 weeks of exposure indicating a compensatory change. Likewise, CD45/CD68-positive inflammatory cells did not accumulate in the livers until after LSEC porosity was decreased, indicating that inflammation is a consequence and not a cause of the arsenic-induced LSEC phenotype. The data demonstrate that the liver vasculature is an early target of pathogenic arsenic effects and that the mouse liver vasculature is a sensitive model for investigating vascular health effects of arsenic.",
Arsenic,1026496,"Elevated urine arsenic: un-speciated results lead to unnecessary concern and further evaluations Abstract: The consumption of seafood within two to three days of testing can increase total urine arsenic concentrations. Few clinicians are familiar with this fact and often misinterpret elevated results. A retrospective chart review of all cases with arsenic testing seen between 1991 and 2004 at an occupational and environmental medicine referral clinic was performed. Urine arsenic results were classified as follows: total arsenic levels; speciated results (inorganic, ionic arsenic); and whether the patient abstained from seafood prior to the collection. Laboratory detection limits for total and for ionic arsenic were &lt; or = 2 microg/L. Fifty-four patients with urine arsenic testing were identified. The total urine arsenic concentration exceeded 40 microg/L for 28 patients. On paired, speciated testing (n = 21), mean total arsenic was 122 +/- 227 microg/L, and ionic arsenic was not detected in any of these same samples (p = 0.023). On paired testing, before and after seafood abstention (n = 12), total urine arsenic without abstention was 291 +/- 267 microg/L, and it was only 9 +/- 12 microg/L after seafood abstention (p = 0.004). The total urine arsenic elevations observed in our series were due to benign organic arsenic compounds commonly found in seafood. Laboratories should reflexively perform speciation on most samples with elevated total arsenic concentrations prior to reporting the results. Reflexive speciation could reduce unnecessary referrals, further testing, and patient anxiety.",
Arsenic,2064295,"Mobilization and re-adsorption of arsenate on ferrihydrite and hematite in the presence of oxalate Abstract: In this study, mobilization and re-adsorption of arsenate on 2-line ferrihydrite and hematite in the presence of oxalate was investigated. Our results showed that arsenate could be mobilized during the dissolution of ferrihydrite and hematite. After reaching the maximum values, the released arsenate could re-adsorb on the residual ferrihydrite, whereas such an observation was not significant in hematite system. More reactive sites exposed during the dissolution of ferrihydrite could contribute to the re-adsorption of the released arsenate at pH 3.0, while the insignificant re-adsorption of arsenate on hematite could be explained by the inhibitory adsorption effect of oxalate on arsenate. Although dissolution rates of iron oxides decreased with the increase of arsenate on both ferrihydrite and hematite, dissolution rate was mainly determined by the reactivity of iron oxides, and ferrihydrite showed a higher reactivity than hematite in the presence of oxalate. Mathematic model proposed in our study further indicated that arsenate loading showed a more significant effect on arsenate mobilization in hematite system, while it was more effective in arsenate re-adsorption in ferrihydrite system.",
Arsenic,1508582,"The prokaryotic community of a historically mining-impacted tropical stream sediment is as diverse as that from a pristine stream sediment Abstract: Mining negatively affects the environment by producing large quantities of metallic tailings, such as those contaminated with arsenic, with harmful consequences for human and aquatic life. A culture-independent molecular analysis was performed to assess the prokaryotic diversity and community structural changes of the tropical historically metal-contaminated Mina stream (MS) and the relatively pristine Mutuca stream (MTS) sediments. A total of 234 bacterial operational taxonomic units (OTUs) were affiliated with 14 (MS) and 17 (MTS) phyla and 53 OTUs were associated with two archaeal phyla. Although the bacterial community compositions of these sediments were markedly distinct, no significant difference in the diversity indices between the bacterial communities was observed. Additionally, the rarefaction and diversity indices indicated a higher bacterial diversity than archaeal diversity. Most of the OTUs were affiliated with the Proteobacteria and Bacteroidetes phyla. Alphaproteobacteria, Gemmatimonadetes and Actinobacteria were only found in the MS clone library. Crenarchaeal 16S rDNA sequences constituted 75 % of the MS archaeal clones, whereas Euryarchaeota were dominant in the MTS clones. Despite the markedly different characteristics of these streams, their bacterial communities harbor high diversity, suggesting that historically mining-impacted sediments promote diversity. The findings also provide basis for further investigation of members of Alphaproteobacteria as potential biological indicators of arsenic-rich sediments.",
Arsenic,1019359,"Differential sensitivities of MRP1-overexpressing lung tumor cells to cytotoxic metals Abstract: The human multidrug-resistance protein (MRP1), known to mediate cellular efflux of a wide range of xenobiotics, including anticancer drugs, has also been shown to transport antimony, thereby conferring resistance to this heavy metal. The aim of the present study was to investigate whether other cytotoxic metals could be handled by MRPI using MRP1-overexpressing lung tumor GLC4/Sb30 cells. Such cells were found to be 3.4-, 12.7- and 16.3-fold more resistant than parental GLC4 cells to mercuric ion, arsenite and arsenate, respectively, whereas they remained sensitive to other cytotoxic metals tested such as copper, chromium, cobalt or aluminium. MK571, a potent inhibitor of MRP1 activity, almost totally reversed resistance of GLC4/Sb30 cells to mercuric ions and arsenic while it did not significantly alter sensitivity of GLC4 cells to metals. Arsenate-treated GLC4/Sb30 cells were found to poorly accumulate arsenic through increased MK571-inhibitable efflux of the metal. Arsenate, however, failed to alter MRP1-mediated transport of known MRP1 substrates such as calcein and vincristine. In conclusion, these findings demonstrated that MRP1 likely handled some, but not all, cytotoxic metals such as arsenic and mercuric ions in addition to antimony, therefore resulting in reduced toxicity of these compounds towards MRP1-overexpressing cells.",
Arsenic,732046,"Use of black tea in modulating clastogenic effects of arsenic in mice in vivo Abstract: The concentration of arsenic in drinking water has far exceeded the permissible limit of 0.001 mg/L and has reached epidemic proportions, with a maximum of 3.7 mg/L in several districts of West Bengal and in the adjoining Bangladesh. Because inorganic arsenic is a documented human carcinogen, arsenic in drinking water may cause 200,000-270,000 deaths per year from cancer in India alone. Tea has a protective effect against the clastogenicity of arsenic. We investigated whether tea extracts could protect against the damage caused by arsenic in vivo. Our experiments were carried out with black tea in mice with the end points of incidence of chromosomal aberrations and damaged cells. Analysis of variance of chromosomal aberrations showed a significant difference in the toxic effects of arsenic, which were reduced by tea infusion. The frequency of chromosomal aberrations was close to the corresponding effects of tea alone. Continued dietary administration of black tea infusion protects against the chromosome-damaging effects of sodium arsenite at a statistically significant level. The degree of protection increases with duration of tea consumption, which may be attributed to the antioxidant and scavenging properties of tea infusion.",
Arsenic,1385189,REMOVAL OF ARSENIC FROM LEAD SMELTER SPEISS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXICITY SULFUR CARBON MONOXIDE,
Arsenic,1339451,"Water consumption patterns and factors contributing to water consumption in arsenic affected population of rural West Bengal, India Abstract: A direct water intake study was conducted for one year, involving 423 individuals from three arsenic (As) affected villages of West Bengal, India. Average direct water intake per person and per unit body weight was found to be 3.12±1.17L/day and 78.07±47.08mL/kg/day (± SD), respectively. Average direct water intakes for adult males, adult females and children (age &lt;15years) were 3.95, 3.03 and 2.14L/day, respectively. Significant sex differentials were observed between ages 16-55years. For all participants, a sharp increase in water intake up to 15years of age was observed followed by a plateau at a higher intake level. Significant monthly, seasonal, regional, and occupational variability was also observed. Another study involving 413 subjects determined the amount of indirect water intake. Average indirect water intake per person was 1.80±0.64L/day; for adult males, adult females and children, intake was 2.15, 1.81, and 1.10L/day, respectively. Average total (direct + indirect) water intake was 4.92L/person/day; for adult males, adult females and children, total intake was 6.10, 4.84, and 3.24L/person/day, respectively. The overall contribution of indirect water intake to total water consumption was 36.6% for all participants. This study additionally elucidated several factors that contribute to variable water intake, which can lead to better risk characterization of subpopulations and water contaminant ingestion. The study reveals that the water intake rates in the three studied populations in West Bengal are greater than the assumed water intake rates utilized by the World Health Organization (WHO) in the establishment of drinking water quality guidelines; therefore, these assumed intake values may be inappropriate for the study population as well as similar ones.",
Arsenic,1352711,"PATHWAYS OF ARSENIC UPTAKE AND INCORPORATION IN ESTUARINE PHYTOPLANKTON AND THE FILTER-FEEDING INVERTEBRATES EURYTEMORA-AFFINIS, BALANUS-IMPROVISUS AND CRASSOSTREA-VIRGINICA Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenic uptake from water and from phytoplankton was followed in the copepod Eurytemora affinis and the barnacle Balanus improvisus collected from the Patuxent River estuary, Chesapeake Bay, eastern coast of the USA in 1987, and in the oyster Crassostrea virginica obtained from a hatchery on the shore of Chesapeake Bay in 1987. Dissolved arsenic was readily taken up by phytoplankton and by shell material of B. improvisus and C. virginica; however, no dissolved arsenic was incorporated into the invertebrate tissues. When E. affinis, B. improvisus and C. virginica were fed phytoplankton containing elevated arsenic contents, significant arsenic incorporation occurred. Juvenile B. improvisus incorporated relatively more arsenic than adults of all three species. Compared to the 100 to 200% increase in arsenic content by phytoplankton exposed to dissolved arsenic, the 25 to 50% increase in these invertebrate species via trophic transfer is relatively small. Even though the t",
Arsenic,1936124,The rise and demise of control options for fruit fly in Australia Abstract: ,
Arsenic,1597453,"Effect of Quick Lime and Dolomite Application on Mobility of Elements (Cd, Zn, Pb, As, Fe, and Mn) in Contaminated Soils Abstract: ",
Arsenic,1029560,"Enhanced ROS production and redox signaling with combined arsenite and UVA exposure: contribution of NADPH oxidase Abstract: Solar ultraviolet radiation (UVR) is the major etiological factor in skin carcinogenesis. However, in vivo studies demonstrate that mice exposed to arsenic and UVR exhibit significantly more tumors and oxidative DNA damage than animals treated with either agent alone. Interactions between arsenite and UVR in the production of reactive oxygen species (ROS) and stress-associated signaling may provide a basis for the enhanced carcinogenicity. In this study keratinocytes were pretreated with arsenite (3 microM) and then exposed to UVA (10 kJ/m(2)). We report that exposure to UVA after arsenite pretreatment enhanced ROS production, p38 MAP kinase activation, and induction of a redox-sensitive gene product, heme oxygenase-1, compared to either stimulus alone. UVR exposure resulted in rapid and transient NADPH oxidase activation, whereas the response to arsenite was more pronounced and persistent. Inhibition of NADPH oxidase decreased ROS production in arsenite-treated cells but had little impact on UVA-exposed cells. Furthermore, arsenite-induced, but not UVA-induced, p38 activation and HO-1 expression were dependent upon NADPH oxidase activity. These findings indicate differences in the mechanisms of ROS production by arsenite and UVA that may provide an underlying basis for the observed enhancement of redox-related cellular responses upon combined UVA and arsenite exposure.",
Arsenic,1015837,"Effects of prenatal exposure to sodium arsenite on motor and food-motivated behaviors from birth to adulthood in C57BL6/J mice Abstract: Consumption of arsenic-contaminated drinking water is associated with numerous cancers and dermal and vascular diseases. Arsenic is also a potent nervous system toxicant and epidemiological studies indicate that intellectual functions in children are compromised following early developmental exposure. This study was designed to examine the effects of arsenic on a broad range of age-specific behaviors including basic sensory-motor responses in neonates, locomotor activity and grip strength in juveniles, and operant measures of learning and attention in adults. Pregnant C57BL6/J mice consumed drinking water containing 0, 8, 25, or 80ppm sodium arsenite from the fourth day of gestation until birth. Arsenic produced a range of behavioral impairments in male and female offspring at each of the test ages. The most striking effects of arsenic were on the development of gait and other motor responses including acoustic startle, righting reflexes, and forelimb grip. These results suggest that developmental arsenic exposure can produce other behavioral impairments in children in addition to cognitive impairment.",
Arsenic,1509342,"Surfactant-free preparation of nickel carbonate hydroxide in aqueous solution and its toxic ion-exchange properties Abstract: In this paper, we have demonstrated a simple surfactant-free solution method for the synthesis of sea urchin-like nickel carbonate hydroxide, which was characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermal gravimetric analysis, nitrogen adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Two types of carbonate species, a surface unidentate carbonate-like species and a crystal lattice carbonate species, were proposed based on the FTIR and symmetry analysis. The toxic ion-exchange properties towards As(V), Cd(II), and Cu(II) ions were investigated. At pH 5.0, the exchange capacities of Cd(II) and Cu(II) ions were 120.5 and 109.3 mg g?1, respectively, through the ion-exchange between nickel ions with them, which was confirmed by XPS. For As(V) ion removal, the maximum exchange capacity was 49.6 mg g?1 without any pH adjustment, which should be of importance for water treatment. Furthermore, a novel ion-exchange mechanism between the surface unidentate carbonate-like species and As(V) ions was proposed, which was revealed by XPS and FTIR.",
Arsenic,1034066,"Precursor stage of hepatocellular neoplasm following long exposure to orally administered contraceptives Abstract: Hepatic neoplasms and peliosis are known to occur in women taking contraceptives orally. We observed hyperplasia of hepatocytes combined with hypertrophy of sinusoidal lining cells and sinusoidal dilatation with progression to peliosis in the liver of a patient who had been taking such contraceptives for 10 years. These changes resembled the precursor stage in the development of hepatic angiosarcoma induced by vinyl chloride, Thorotrast, and arsenic. In users of orally administered contraceptives these findings may precede the development of hepatocellular neoplasms.",
Arsenic,735092,"Bladder cancer mortality trends and patterns in Córdoba, Argentina (1986–2006) Abstract: BACKGROUND: Bladder cancer is common worldwide and the fourth most commonly diagnosed malignancy in men in Argentina. OBJECTIVE: To describe bladder cancer mortality trends in Córdoba (1986-2006), considering the effect of age, period, and cohort, and to estimate the effect of arsenic exposure on bladder cancer, and its interaction with sex, while controlling by smoking habits and space and time variation of the rates. METHODS: A joinpoint regression was performed to compute the estimated annual percentage changes (EAPC) of the age-standardized mortality rates (ASMR) in an adult population from Córdoba, Argentina. A Poisson model was fitted to estimate the effect of age, period, and cohort. The influence of gender, tobacco smoking (using lung cancer ASMR as surrogate), and arsenic in drinking water was examined using a hierarchical model. RESULTS: A favorable trend (1986-2006) in bladder cancer ASMR in both sexes was found: EAPC of -2.54 in men and -1.69 in women. There was a decreasing trend in relative risk (RR) for cohorts born in 1931 or after. The multilevel model showed an increasing risk for each increase in lung cancer ASMR unit (RR = 1.001) and a biological interaction between sex and arsenic exposure. RR was higher among men exposed to increasing As-exposure categories (RR male low exposure 3.14, RR male intermediate exposure 4.03, RR male high exposure 4.71 versus female low exposure). A non-random space-time distribution of the rates was observed. CONCLUSIONS: There has been a decreasing trend in ASMR for bladder cancer in Córdoba. This study confirms that bladder cancer is associated with age, gender, smoking habit, and exposure to arsenic. Moreover, an effect measure modification between exposure to arsenic and sex was found",
Arsenic,1348541,"HEAT-SHOCK RESPONSIVE ELEMENTS IN THE INDUCTION OF THE MULTIDRUG RESISTANCE GENE (MDR1) Abstract: The MDR1 gene, considered to be involved in multidrug resistance of cancer cells, is expressed in liver, kidney, small intestine and the blood-brain barrier. We investigated MDR1 gene expression in the well-differentiated hepatoma cell line HepG2 after exposure to several stresses and found that sodium arsenite treatment increased MDR1 gene expression 2.6-fold. Deletion analysis of the MDR1 promoter indicated that the transcriptional activation after exposure to arsenite depends on a 60-bp region containing two heat-shock responsive elements.",
Arsenic,710968,"Interactive effect of arsenic and fluoride on cardio-respiratory disorders in male rats: possible role of reactive oxygen species Abstract: Epidemiological evidence demonstrates positive correlation between environmental and occupational arsenic or fluoride exposure and risk to various cardio-respiratory disorders. Arsenic-exposure has been associated with atherosclerosis, hypertension, cerebrovascular diseases, ischemic heart disease, and peripheral vascular disorders, whereas Fluoride-exposure manifests cardiac irregularities and low blood pressure (BP). Present study aims to study the combined effects of these toxicants on various cardio-respiratory variables in male rats. Single intravenous (i.v.) dose of arsenic (1, 5, 10 mg/kg) or fluoride (5, 10, 20, 36.5 mg/kg) either alone or in combination were administered. Individual exposure to arsenic or fluoride led to a significant depletion of mean arterial pressure, heart rate (HR), respiration rate and neuromuscular (NM) transmission in a dose-dependent manner. These changes were accompanied by increased levels of blood reactive oxygen species (ROS) and decreased glutathione (GSH) concentrations. An increase in the blood acetyl cholinesterase (AChE) activity was observed in both arsenic or fluoride exposed rats. These changes were significantly more pronounced in arsenic-exposed animals than in fluoride. During combined exposure to arsenic (5 mg/kg) + fluoride (20 mg/kg) or arsenic (10 mg/kg) + fluoride (36.5 mg/kg) the toxic effects were more pronounced compared to individual toxicities of arsenic or fluoride alone. However, combined exposure to arsenic (5 mg/kg) + fluoride (36.5 mg/kg) resulted in antagonistic effects on variables suggestive of altered cardio-respiratory function and oxidative stress. The results from the present study suggest that arsenic or fluoride individually demonstrate cardio-respiratory failure at all doses whereas during combination exposure these toxins show variable toxicities; both synergistic and antagonistic effects depending upon the dose. Moreover, it may be concluded that arsenic and/or fluoride cardio-respiratory toxicity may be mediated via oxidative stress. However, these results are new in the discipline thus requires further exploration.",1
Arsenic,1015742,"Do radial oxygen loss and external aeration affect iron plaque formation and arsenic accumulation and speciation in rice? Abstract: Hydroponic experiments were conducted to investigate the effect of radial oxygen loss (ROL) and external aeration on iron (Fe) plaque formation, and arsenic (As) accumulation and speciation in rice (Oryza sativa L.). The data showed that there were significant correlations between ROL and Fe concentrations in Fe plaque produced on different genotypes of rice. There were also significant differences in the amounts of Fe plaque formed between different genotypes in different positions of roots and under different aeration conditions (aerated, normal, and stagnant treatments). In aerated treatments, rice tended to have a higher Fe plaque formation than in a stagnant solution, with the greatest formation at the root tip decreasing with increasing distances away, in accordance with a trend of spatial ROL. Genotypes with higher rates of ROL induced higher degrees of Fe plaque formation. Plaques sequestered As on rice roots, with arsenate almost double that with arsenite, leading to decreased As accumulation in both roots and shoots. The major As species detected in roots and shoots was arsenite, ranging from 34 to 78% of the total As in the different treatments and genotypes. These results contribute to our understanding of genotypic differences in As uptake by rice and the mechanisms causing rice genotypes with higher ROL to show lower overall As accumulation.",
Arsenic,1033330,"Assessment of occupational exposure to arsenic, copper, and lead in a western copper smelter Abstract: A comprehensive industrial hygiene survey was conducted at a western copper smelter and arsenic trioxide production facility. The major contaminants reported are arsenic, copper, and lead. The greatest concern noted was for the arsenic measurements found, 69% of which exceeded the 10 micrograms/M3 permissible exposure limit. The company must use a combination of feasible engineering and administrative controls as well as a sophisticated respiratory protection program, however, the efficacy of that program will require continued study and evaluation.",
Arsenic,1070484,"Blockade of p53 by HIF-2?, but not HIF-1?, is involved in arsenite-induced malignant transformation of human bronchial epithelial cells Abstract: Hypoxia-inducible factors (HIFs), which consist of ? and ? subunits, are transcription factors involved in regulation of a variety of cellular functions. By blocking the function of the tumor suppressor p53, over-expressions of HIFs are linked to carcinogenesis and tumor progression. Inorganic arsenic, a ubiquitous environmental contaminant, is associated with an increased risk of cancer. Although there are several hypotheses regarding arsenic-induced carcinogenesis, the mechanism of action remains obscure. We have shown that long-term exposure of human bronchial epithelial (HBE) cells to a low level of arsenite increases their proliferation rate and anchorage-independent growth. When introduced into nude mice, the transformed cells are tumorigenic. The present report demonstrates that, with increased time of exposure to arsenite, there is more increased expression of HIF-2?, but not HIF-1?. These factors are known to have different functions, and, in some cases, opposite effects. Arsenite induces accumulation of HIF-2? by inhibiting its degradation through the ubiquitin-mediated proteasome pathway. HIF-2? knockdown, but not HIF-1? knockdown, increases the activation of p53. Finally, inhibition of HIF-2? blocks arsenite-induced proliferation and malignant transformation. Thus, our studies show that blockade of p53 function by inhibiting the ubiquitin-mediated proteasome degradation of HIF-2?, but not that of HIF-1?, is involved in arsenite-induced proliferation and neoplastic transformation of HBE cells.",
Arsenic,2337238,"Heavy metals in fish from the Aleutians: Interspecific and locational differences Abstract: The objectives of this study were to examine levels of arsenic, cadmium, lead, mercury and selenium in edible tissue of seven species of marine fish collected from several Aleutian islands (in 2004) to determine: (1) interspecific differences, (2) locational differences (among Aleutian Islands), (3) size-related differences in any metal levels within a species, and (4) potential risk to the fish or to predators on the fish, including humans. We also compared metals levels to those of three other fish species previously examined in detail, as well as examining metals in the edible tissue of octopus (Octopus dofleini). Octopus did not have the highest levels of any metal. There were significant interspecific differences in all metal levels among the fish species, although the differences were less than an order of magnitude, except for arsenic (mean of 19,500 ppb in Flathead sole, Hippoglossoides elassodon). Significant intraisland variation occurred among the four sites on Amchitka, but there was not a consistent pattern. There were significant interisland differences for some metals and species. Mercury levels increased significantly with size for several species; lead increased significantly for only one fish species; and cadmium and selenium decreased significantly with size for halibut (Hippoglossus stenolepis). The Alaskan Department of Health and Social Services supports unrestricted consumption of most Alaskan fish species for all people, including pregnant women. Most mean metal concentrations were well below the levels known to adversely affect the fish themselves, or predators that consume them (including humans), except for mercury in three fish species (mean levels just below 0.3 ppm), and arsenic in two fish species. However, even at low mercury levels, people who consume fish almost daily will exceed guideline values from the Centers for Disease Control and the Environmental Protection Agency.",
Arsenic,1579387,"Elemental composition and nutritional value of the edible fruits of Harpephyllum caffrum and impact of soil quality on their chemical characteristics Abstract: Harpephyllum caffrum is a medicinal plant and common street tree distributed throughout the eastern part of South Africa. The elemental concentration in the edible fruit of H. caffrum was determined to assess for nutritional value and health impact. Concentrations of metals in the fruit and growth soil were determined from samples acquired from eight different sites in eastern KwaZulu-Natal, South Africa, to evaluate the impact of soil parameters on elemental distribution in the fruit. Typical elemental concentrations (?g g(-1), dry mass) in soil (Exchangeable/Total) and fruit samples, at Umhlanga, north of Durban, were Ca (1221/696 and 3333), Co (2.5/2.1 and 0.16), Cr (35/0.8 and 5.8), Cu (14/9 and 21), Fe (9424/394 and 116), Mg (199/139 and 915), Mn (268/187 and 13), Ni (2.8/0.51 and 3.4), Pb (36/32 and 1.2), and Zn (26/21 and 15). The analytical results showed that metal interactions in soil influenced their availability, but uptake was to a greater extent controlled by the plant. The concentrations of elements in the fruits were found to be in the order of Ca &gt; Mg &gt; Fe &gt; Cu &gt; Zn &gt; Mn &gt; Cr &gt; Ni &gt; Pb &gt; Co. The concentrations of toxic metals, arsenic and lead were low. The fruits can contribute to the health and nutritional needs of individuals for most elements. It has potential to improve the Fe status and contribute towards a balanced diet.",
Arsenic,627271,"Effect of chronic intake of arsenic-contaminated water on liver Abstract: The hepatotoxic effect of arsenic when used in therapeutic dose has long been recognized. We described the nature and degree of liver involvement and its pathogenesis due to prolonged drinking of arsenic-contaminated water in West Bengal, India. From hospital-based studies on 248 cases of arsenicosis, hepatomegaly was found in 190 patients (76.6%). Non cirrhotic portal fibrosis was the predominant lesions in 63 out of 69 cases who underwent liver biopsy. The portal fibrosis was characterized by expansion of portal zones with streaky fibrosis, a few of which contained leash of vessels. However, portal hypertension was found in smaller number of cases. A cross-sectional epidemiological study was carried out on 7683 people residing in arsenic-affected districts of West Bengal. Out of these, 3467 and 4216 people consumed water-containing arsenic below and above 0.05 mg/l, respectively. Prevalence of hepatomegaly was significantly higher in arsenic-exposed people (10.2%) compared to controls (2.99%, P < 0.001). The incidence of hepatomegaly was found to have a linear relationship proportionate to increasing exposure of arsenic in drinking water in both sexes (P < 0.001). In an experimental study, BALB/C mice were given water contaminated with arsenic (3.2 mg/l) ad libitum for 15 months, the animals being sacrificed at 3-month intervals. We observed progressive reduction of hepatic glutathione and enzymes of anti-oxidative defense system associated with lipid peroxidation. Liver histology showed fatty infiltration at 12 months and hepatic fibrosis at 15 months. Our studies show that prolong drinking of arsenic-contaminated water is associated with hepatomegaly. Predominant lesion of hepatic fibrosis appears to be caused by arsenic induced oxystress.",
Arsenic,1597364,"Temporal trends (1986-2005) of essential and non-essential elements in a terrestrial raptor in northern Europe Abstract: In the recent decades, the atmospheric deposition of many metals has declined in northern Europe, mostly due to reductions of emissions in other parts of the Europe. However, less is known about the temporal trends at higher trophic levels in terrestrial food chains. In this study we measured 39 different essential and non-essential elements in tawny owl (Strix aluco) tail-feathers (n=633) collected annually between 1986 and 2005 in Central Norway. There was a strong decline in lead (Pb) concentrations (~94%) consistent with the termination of the use of Pb as a petrol additive. There were also significant declines in cadmium (Cd), cobalt (Co) and arsenic (As) concentrations. Zinc (Zn) may also have declined after 2000, but this is not yet clear due to possible analytical problems. More unexpected was a strong decline of boron (B) in the late 1980s and early 1990s with a subsequent leveling-off, but with high concentrations in 1999. The decline in B could be related to changes in the agricultural practices and use of fertilizers. Tin (Sn) showed an abrupt decline in the mid-1990s, after which the concentrations established at one fifth of the level before this time. Iron (Fe) was stable until the late 1990s, but showed an increase afterwards, whereas lanthanum (La) tended to increase up to the mid-1990s and then leveled-off. Aluminum (Al) showed decreasing levels until the mid-1990s, but a considerable increase afterwards. There was a small increase in praseodymium (Pr), but the only element showing a consistent strong increase over the study period (61%) was rubidium (Rb). The causes of the temporal trends in different elements may be changed input to the local ecosystem from local and trans-boundary sources, but possibly also variation in climate and feeding conditions for the owls.",
Arsenic,759699,"Nitric oxide donor, V-PROLI/NO, provides protection against arsenical induced toxicity in rat liver cells: Requirement for Cyp1a1 Abstract: Arsenic is a cancer chemotherapeutic but hepatotoxicity can be a limiting side effect. O(2)-vinyl 1-[2-(carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate (V-PROLI/NO) is a nitric oxide (NO) donor prodrug and metabolized by liver cytochromes P450 (CYP450) to release NO. The effects of V-PROLI/NO pretreatment on the toxicity of arsenic (as NaAsO(2)) were studied in a rat liver cell line (TRL 1215). The cells acted upon the prodrug to release NO, as assessed by nitrite levels, in a time-dependent fashion to maximal levels of 8-fold above basal levels. Pretreatment with V-PROLI/NO markedly reduced arsenic cytolethality which was directly related to the level of NO produced by V-PROLI/NO treatment. Cyp1a1 expression was directly related to the level of NO production and to reduced arsenic cytotoxicity. V-PROLI/NO pretreatment markedly reduced arsenic-induced apoptosis and suppressed phosphorylation of JNK1/2. V-PROLI/NO pretreatment facilitated additional increases in arsenic-induced metallothionein, a metal-binding protein important in arsenic tolerance. Thus, V-PROLI/NO protects against arsenic toxicity in rat liver cells, reducing cytolethality, apoptosis and dysregulation of MAPKs, through generation of NO formed after metabolism by liver cell enzymes, possibly including Cyp1a1. CYP450 required for NO production from V-PROLI/NO treatment in the rat and human appears to differ as we have previously studied the ability of V-PROLI/NO to prevent arsenic toxicity in human liver cells where it reduced toxicity apparently through a CYP2E1-mediated metabolic mechanism. None-the-less, it appears that both rat and human liver cells act upon V-PROLI/NO via a CYP450-related mechanism to produce NO and subsequently reduce arsenic toxicity.",
Arsenic,1597411,"Combined toxicity of ferroferric oxide nanoparticles and arsenic to the ciliated protozoa Tetrahymena Pyriformis Abstract: Fe3O4 nanoparticles (NPs) have a high affinity for arsenic. As a result of this association, Fe3O4 NPs loaded with high concentration of arsenic can enter into organisms and produce locally high concentrations of arsenic, which may lead to some unexpected toxicity to aquatic organisms. The objectives of this research were to investigate the toxic effect of Fe3O4 NPs in combination with As(V). Cultured Tetrahymena pyriformis was chosen as a research model organism to evaluate the toxic effects of the combined agents. The results showed that after 24 h of As(V) exposure, the median effective concentration of As(V) to T. pyriformis was 1.29 mg/L. Fe3O4 NPs alone were not only non-toxic, but actually promoted the growth of T. pyriformis at the experimental doses. After 24 h exposure, the cell number increased by 32.2% at an exposure level of 3 mg/L Fe3O4 NPs. After 24 h exposure to 1.0 mg/L As(V), the survival rate increased from 60.5% in the absence of Fe3O4 NPs to 73.8% and 83.8% in the presence of 13 mg/L and 19 mg/L Fe3O4 NPs, respectively. However, after 30 h, the combined toxic effect of As(V) and Fe3O4 NPs on T. pyriformis was significantly enhanced and the survival rates for co-exposure to 1.5 mg/L As(V) and 13 mg/L Fe3O4 NPs decreased from 92.3% after 18 h to 45.3% after 30 h. After 18 h of exposure to Fe3O4 NPs alone, the intracellular ROS levels were markedly increased and achieved steady state. Compared with the control group, the intracellular ROS levels were significantly increased (2.56-fold) by the combination of 19 mg/L Fe3O4 NPs and 1.0 mg/L As(V). Accumulation of As(V) in T. pyriformis led to an increase in trivalent arsenics as a result of the saturation of the cellular arsenic methylation capability or/and redox reactions. These exposures also resulted in an imbalance between oxidants and antioxidants, resulting in oxidative damage and cell death.",
Arsenic,628683,"Sodium arsenite inhibits terminal differentiation of murine C3H 10T1/2 preadipocytes Abstract: Cancer represents an imbalance between cell proliferation and differentiation, two processes that are coordinately and antagonistically regulated. Aberrant cell proliferation is considered to be an important etiological factor in the development of arsenic-induced cancer, suggesting that arsenic also dysregulates differentiation. Based on evidence that arsenic modulates mitogenic events that antagonize the process of differentiation, this study addresses the hypothesis that sodium arsenite inhibits insulin/dexamethasone-induced differentiation of C3H 10T1/2 preadipocytes; it was further postulated that arsenic-treated cells retain mitogenic responsiveness under differentiating conditions. To test this hypothesis, the differentiation capacity of C3H 10T1/2 preadipocytes was examined in control cells and cells treated with sodium arsenite. Differentiation was assessed morphologically and quantified by Oil Red-O staining of accumulated lipids. The effect of long-term arsenic exposure on mitogenic competence was quantified by flow cytometry, [3H]thymidine incorporation, and cell counting under conditions favorable for adipocyte differentiation. Results indicate that arsenic inhibits morphological differentiation of wild-type C3H 10T1/2 preadipocytes. Short-term arsenic exposure inhibits differentiation in a dose-dependent manner, with arsenic concentrations ?3 ?M producing a significant inhibition of dexamethasone/insulin-induced lipid accumulation. Furthermore, arsenic-treated cells exhibit an accentuated response to mitogenic stimulation under differentiating conditions. These data suggest that arsenic exposure results in the inhibition of cellular programming required for terminal differentiation of C3H 10T1/2 preadipocytes and that cells acquire mitogenic hyperresponsiveness. The ability of arsenic to dysregulate the balance between proliferation and differentiation is proposed to be one mechanism by which this metalloid causes cancer in humans.",
Arsenic,2345714,"CAPACITY OF TROPICAL FOREST SOILS OF FRENCH GUIANA AND REUNION FOR DEPOLLUTING THE WOODS IMPREGNATED WITH BIOCIDES Abstract: Wood material for a long time was treated with fungicides or insecticides whose impact on the soil after leaching constitutes a real environmental problem. Nowadays, most of the studies on degradation of these toxic products was carried out with microorganisms which have been isolated in the laboratory. The present study sought to refine the knowledge vis-a-vis these microorganisms, especially wood-destroying fungi degrading pollutants in situ, from which few data are actually available. To decontaminate treated wood, the capacity of wood-destroying microorganisms from tropical forest soils of French Guiana and Reunion was evaluated to degrade toxic biocides. These are pentachlorophenol (PCP) and copper- chromium arsenic based compounds (CCA). Monitoring the degradation of samples of red pine, Pinus resinosa, shows that soils of French Guiana are more efficient than those of Reunion Island in terms of microbial activity vis-a-vis these two biocides. A significant difference in loss of mass in specimens of red pine treated with CCA and PCP can range from single to double (respectively 18% and 30%). These findings confirm that CCA is less leacher and less degradable than the PCP by microorganisms in the soil. According to the scale of mass loss in laboratory tests, the wood so treated would be classified very not durable after three years of contact with soil, while the treatment is expected to be very durable.",
Arsenic,2064258,"Multivariate analysis of heavy metal contaminations in seawater and sediments from a heavily industrialized harbor in Southern Taiwan Abstract: Heavy metal pollution, including chromium, zinc, arsenic, cadmium, mercury, copper, lead, and aluminum, in the largest industrial harbor in southern Taiwan was investigated. Increasing metal contamination was observed by monitoring heavy metal concentrations in seawater and sediments and estimating the enrichment factors, particularly those inside the harbor. Compared to other metal-polluted harbors worldwide, the presence of chromium in the sediments was relatively high. Excluding the background contribution, the harbor area was polluted by outflows from river mouths, wastewater discharging pipes, and point sources near industrial activities within the harbor. It is shown by principal component and cluster analyses that metal contamination was affected by a wide range of different and complex contamination mechanisms inside and outside the harbor, suggesting managing the pollution using straightforward strategies, i.e., solutions that only consider a single source or single pathway of metal emissions, is problematic.",
Arsenic,1026275,"The influence of exposure history on arsenic accumulation and toxicity in the killifish, Fundulus heteroclitus Abstract: Exposure to arsenic is known to cause adverse effects in aquatic biota and wildlife and is of major concern to human health. Although numerous studies have investigated the toxicity of arsenic, little is known about the effects of acquired tolerance on arsenic accumulation and toxicity outside of cell culture models. Accordingly, studies were conducted on the estuarine fish, Fundulus heteroclitus, that were preexposed to nontoxic concentrations of arsenic (as sodium arsenite; 0.7 and 106 micromol As/L) for 96 h or naïve to elevated arsenic to determine the effects of acclimation on arsenic toxicity and accumulation. Tolerance to arsenic was rapidly (96 h) acquired in killifish that were preexposed. In toxicity tests with arsenic-acclimated killifish, preexposure to 106 micromol As/L resulted in a reduction in toxicity when compared to naïve animals. Toxicity in arsenic-acclimated fish also was distinguished by a delayed onset of mortality that manifested in dose-dependent fashion and was significant even for the lower acclimation concentration (0.7 micromol As/L). The increase tolerance acquired following preexposure to 106 micromol As/L for 96 h was associated with lower concentrations of arsenic in all monitored tissues (e.g., gill, liver, kidney) and the whole body when fish were exposed to 240 micromol As/L for an additional 96 h. In accordance with these observations, expression of the multidrug resistance- associated protein (MRP)-2 gene, which is responsible for transporting arsenic conjugated to glutathione out of cells, was increased in the liver of arsenic-acclimated fish.",
Arsenic,1025432,"Arsenite-induced cytotoxicity in dorsal root ganglion explants Abstract: Peripheral neuropathy is common in people chronically overexposed to arsenic. We studied sodium arsenite (arsenite)-induced cytotoxicity in dorsal root ganglion (DRG) explants. Incubation with arsenite concentration- and time-dependently increased the expression of stress proteins, heat shock protein 70, and heme oxygenase-1 in DRG explants. Furthermore, apoptosis was involved in the arsenite-induced cytotoxicity in the treated DRG. Elevation in cytosolic cytochrome c levels and reduction in procaspase 3 levels suggested an involvement of the mitochondrial pathway in arsenite-induced apoptosis in this preparation. At the same time, increases in the activating transcription factor-4 and C/EBP homologous protein and reduction in procaspase 12 levels indicated activation of the endoplasmic reticulum (ER) pathway in the arsenite-induced cytotoxicity in DRG explants. Salubrinal (30 microM), an ER inhibitor, was found to attenuate arsenite-induced DNA fragmentation and reduction in procaspase 12 in DRG explants. Cytotoxic effects by arsenite, sodium arsenate (arsenate), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were compared, and the potency was as follows: arsenite &gt; arsenate&gt;MMA and DMA. Recombinant adenovirus vectors encoding glial-cell-derived neurotrophic factor (AdGDNF) genes allowed a stable delivery of GDNF genes to the infected cells in DRG explants. Applied in this manner, AdGDNF was found to inhibit arsenite-induced DNA fragmentation in DRG explants. Moreover, AdGDNF attenuated the arsenite-induced reduction in procaspases 3 and 12 levels. Taken together, our study demonstrates that arsenite is capable of inducing cytotoxicity in DRG explants. Both ER and mitochondria pathways are involved in the arsenite-induced apoptosis in DRG explants. Glial-cell-derived neurotrophic factor appears to be protective against arsenite-induced peripheral neuropathy.",
Arsenic,2278545,"Advanced receptor modeling of near-real-time, ambient PM2.5 and its associated components collected at an urban-industrial site in Toronto, Ontario Abstract: PM2.5 and other atmospheric pollutants were continuously monitored at high time resolution for 1 year at an urban-industrial location in Toronto, ON, Canada's largest city. The data collected for these pollutants were examined to determine seasonal trends and potential sources. Advanced receptor models including residence time weighted concentration (RTWC) and simplified quantitative transport bias analysis (sQTBA) trajectory ensemble models (TEM) and conditional probability function (CPF) were applied to these data to identify potential local and regional sources of pollution impacting this receptor site. Seasonal trends showed that concentrations of PM2.5 were more frequently high in winter than in any other season. Median concentrations of lead and arsenic were highest in fall while median levels of chromium were not significantly different over the four seasons. The black carbon-derived measurement commonly known as Delta C (i.e., BC370nm-BC880nm) had its greatest abundance in winter and lowest levels in summer. The seasonality of Delta C is indicative of the impact of residential wood combustion near the receptor site. CPF indicated that lead and iron had the most unidirectional radial plots with sectors located west-southwest of the receptor being the most likely local source regions. Winter CPF for Delta C is almost of equal strengths in all directions suggestive of near-uniform isotropic local impacts. The sQTBA model provided the most satisfactory spatial representation of impacting sources. The strongest sources of PM2.5 identified by the sQTBA model were both local and transboundary in origin. More potential source regions were found in winter and summer than in spring and fall.",
Arsenic,1677650,"In-situ zinc bioprecipitation by organic substrate injection in a high-flow, poorly reduced aquifer Abstract: We investigated if in-situ metal bioprecipitation (ISMP) is applicable to remediate a highly permeable zinc-contaminated aquifer at a metal-processing factory in Maasmechelen, Belgium. A large (more than 200m long and 70m wide) groundwater contamination plume has developed, with zinc concentrations in the range of 1-100mg/L, whereas the legal Flemish clean-up standard is 0.5mg/L. The estimated groundwater flow velocity is in the range 0.2-1m/d. The groundwater is relatively oxidized, naturally low in DOC (&lt;1mg/L) and relatively low in sulfate (40-50mg/L). We conducted both laboratory feasibility tests as well as a long-term field pilot test in two sections of the plume. In the laboratory microcosm tests, zinc bioprecipitation (following addition of organic substrate and sulfate) removed more than 99% of the zinc from the water phase. Lactate, glycerol and vegetable oil were equally effective as substrates. 28-day anaerobic leaching tests indicated that the metal precipitates that were formed are stable, but they also suggested that substrate addition increases the solubility (leachability) of arsenic and manganese. In the field test, Zn concentrations were reduced by 2 to 3 orders of magnitude within the 232 day testing period and stayed low for the following 6 months in both pilot zones. In the field, no mobilization of arsenic occurred but manganese groundwater concentrations increased from 0.01-0.6mg/L to 0.4-6.5mg/L. Dissolved iron concentrations also increased markedly from below detection limits to concentrations as high as 67mg/L. Zinc concentrations in groundwater were closely correlated to pH and redox potential (Eh): plotting y=[Zn] against x=pH/log(Eh), an exponential relationship was found:",
Arsenic,1372609,"Expression of the 31-kD stress protein in rat myoblasts and hepatocytes Abstract: Rat tissue cultures cells respond to stress by inducing the synthesis of about 20 proteins, including two low-molecular-weight species of about 31 kD and 27 kD. We have cloned a cDNA for the 31-kD protein. This protein is induced in myoblasts and hepatoma cells in response to a 43 degrees C heat shock, or exposure to sodium arsenite or cadmium chloride salts. Furthermore, this protein is superinduced in hepatoma cells conditioned to grow in cadmium and zinc salts when they are exposed to a standard sodium arsenite stress. Induction of the gene encoding the 31-kD protein has been characterized as follows: (i) Transcripts accumulate maximally with similar kinetics when myoblasts are induced with either heat shock or sodium arsenite; (ii) accumulation of transcripts decays to preinduction levels within 4 hr of a heat shock, but requires more than 8 days after sodium arsenite stress; (iii) basal levels of transcript are reduced when myoblasts are cultured in the presence of steroid hormones; and (iv) stress induction is virtually abolished once myoblasts have differentiated.",
Arsenic,1337332,"The accumulations of HIF-1? and HIF-2? by JNK and ERK are involved in biphasic effects induced by different levels of arsenite in human bronchial epithelial cells Abstract: The biphasic effects of arsenite, in which low levels of arsenite induce cell proliferation and high levels of arsenite induce DNA damage and apoptosis, apparently contribute to arsenite-induced carcinogenesis. However, the mechanisms underlying this phenomenon are not well understood. In this study, we investigated the effects of different levels of arsenite on cell proliferation, DNA damage and apoptosis as well as on signal transduction pathways in human bronchial epithelial (HBE) cells. Our results show that a low level of arsenite activates extracellular signal-regulated kinases (ERK), which probably mediate arsenite-inhibited degradation of ubiquitinated hypoxia-inducible factor-2? (HIF-2?) in HBE cells. ERK inhibition blocks cell proliferation induced by a low level of arsenite, in part via HIF-2?. In contrast, a high level of arsenite activates c-Jun N-terminal kinases (JNK), which provoke a response to suppress ubiquitinated HIF-1? degradation. Down-regulation of HIF-1? by inhibiting JNK, however, increases the DNA damage but decreases the apoptosis induced by a high level of arsenite. Thus, data in the present study suggest that the accumulations of HIF-1? and HIF-2? by JNK and ERK are involved in different levels of arsenite-induced biphasic effects, with low levels of arsenite inducing cell proliferation and high levels of arsenite inducing DNA damage and apoptosis in HBE cells.",
Arsenic,1340127,"Determination of potentially toxic heavy metals in traditionally used medicinal plants for HIV/AIDS opportunistic infections in Ngamiland District in Northern Botswana Abstract: The determination of four potentially toxic heavy metals, arsenic, chromium, lead and nickel in twelve plant species used for the treatment of perceived HIV and AIDS-associated opportunistic infections by traditional healers in Ngamiland District in Northern Botswana, a metal mining area, was carried out using atomic absorption spectrometry. The medicinal plants; Dichrostachys cinerea, Maerua angolensis, Mimusops zeyheri, Albizia anthelmintica, Plumbago zeylanica, Combretum imberbe, Indigofera flavicans, Clerodendrum ternatum, Solanum panduriforme, Capparis tomentosa, Terminalia sericea and Maytenus senegalensis contained heavy metals in varying quantities: arsenic 0.19-0.54 ?g g(-1), chromium 0.15-1.27 ?g g(-1), lead 0.12-0.23 ?g g(-1) and nickel 0.09-0.21 ?g g(-1) of dry weight. Chromium was found to be the most abundant followed by arsenic and lead. Nickel was undetectable in nine plant species. M. senegalensis contained the largest amounts of arsenic, chromium and lead. All metals determined were below the WHO permissive maximum levels. The possible maximum weekly intakes of the heavy metals following treatment regimes were insignificant compared to the provisional tolerable weekly intake levels recommended by WHO and the Joint FAO/WHO Expert Committee on Food Additives. This suggests that heavy metal exposure to patients originating from consumption of traditional medicinal plant preparations is within non health-compromising limits.",
Arsenic,1936183,"Procedia Earth and Plantetary Science Hydrogeochemical zonation of deep groundwaters near Langshan Mountain of the Hetao basin, Inner Mongolia Abstract: Drinking water in the Hetao basin relies significantly on deep groundwater. Little is known about the occurrence of As and its distribution in deep groundwaters of the Hetao Basin. This study observed that this deep groundwater is affected by the presence of As in a nearby mountainous area. Arsenic concentrations gradually increase from the alluvial fans to the flat plain of the basin. Four hydrogeochemical zones were distinguished based on hydrogeological conditions, together with the distribution of redox-sensitive elements and their relationship with As concentrations. Although As mobilization is fundamentally controlled by the reductive dissolution of Fe-bearing minerals, reduction of SO42-also affects groundwater As concentrations. If the supply of SO42- is sufficient, further reduction of SO42-may lead to a decrease of As levels through co-precipitation with pyrite. This information is helpful for choosing localities for safe drinking water wells in mountain-edge alluvial fans.",
Arsenic,2149136,"Controllable Synthesis of Hierarchical Porous Fe3O4 Particles Mediated by Poly(diallyldimethylammonium chloride) and Their Application in Arsenic Removal Abstract: Hierarchical porous Fe3O4 particles with tunable grain size were synthesized based on a facile poly (diallyldimethylammonium chloride) (PDDA)-modulated solvothermal method. The products were characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 adsorption-desorption technique, vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The results show that increasing the PDDA dosage decrease the grain size and particle size, which increased the particle porosity and enhanced the surface area from 7.05 to 32.75 m(2) g(-1). Possible mechanism can be ascribed to the PDDA function on capping the crystal surface and promoting the viscosity of reaction medium to mediate the growth and assembly of grain. Furthermore, the arsenic adsorption application of the as-obtained Fe3O4 samples was investigated and the adsorption mechanism was proposed. High magnetic Fe3O4 particles with increased surface area display improved arsenic adsorption performance, superior efficiency in low-level arsenic removal, high desorption efficiency, and satisfactory magnetic recyclability, which are very promising compared with commercial Fe3O4 particles.",
Arsenic,1579309,"Life in an arsenic-containing gold mine: Genome and physiology of the autotrophic arsenite-oxidizing bacterium Rhizobium sp. NT-26 Abstract: Arsenic is widespread in the environment and its presence is a result of natural or anthropogenic activities. Microbes have developed different mechanisms to deal with toxic compounds such as arsenic and this is to resist or metabolise the compound. Here we present the first reference set of genomic, transcriptomic and proteomic data of an Alphaproteobacterium isolated from an arsenic-containing goldmine: Rhizobium sp. NT-26. Although phylogenetically related to the plant-associated bacteria, this organism has lost the major colonising capabilities needed for symbiosis with legumes. In contrast, the genome of Rhizobium sp. NT-26 comprises a megaplasmid containing the various genes which enable it to metabolise arsenite. Remarkably, although the genes required for arsenite oxidation and flagellar motility/biofilm formation are carried by the megaplasmid and the chromosome, respectively, a coordinate regulation of these two mechanisms was observed. Taken together, these processes illustrate the impact environmental pressure can have on the evolution of bacterial genomes, improving the fitness of bacterial strains by the acquisition of novel functions.",
Arsenic,1508661,"Characterization of PCBs from computers and mobile phones, and the proposal of newly developed materials for substitution of gold, lead and arsenic Abstract: In this paper, we have analyzed parts of printed circuit board (PCB) and liquid crystal display (LCD) screens of mobile phones and computers, quantitative and qualitative chemical compositions of individual components, and complete PCBs were determined. Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) methods were used to determine the temperatures of phase transformations, whereas qualitative and quantitative compositions of the samples were determined by X-ray fluorescence spectrometry (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and scanning electron microscopy (SEM)-energy dispersive X-ray spectrometry (EDS) analyses. The microstructure of samples was studied by optical microscopy. Based on results of the analysis, a procedure for recycling PCBs is proposed. The emphasis was on the effects that can be achieved in the recycling process by extraction of some parts before the melting process. In addition, newly developed materials can be an adequate substitute for some of the dangerous and harmful materials, such as lead and arsenic are proposed, which is in accordance with the European Union (EU) Restriction of the use of certain hazardous substances (RoHS) directive as well as some alternative materials for use in the electronics industry instead of gold and gold alloys.",
Arsenic,1597458,"Influence of phosphorus on the arsenic uptake by tomato (Solanum lycopersicum L) irrigated with arsenic solutions at four different concentrations Abstract: We have studied the uptake and distribution of arsenic (As) and phosphorus (P) in roots, shoots and berries of tomato plants, grown on uncontaminated soil, irrigated with As-contaminated solutions at four concentrations (0, 0.5, 2 and 4 mg L-1), in presence or absence of P fertilization. The biomass of tomato plants decreased with increasing As concentration in irrigation water, especially tomato berries. In addition, the reduction of biomasses was significantly greater in plants non-fertilized with P. The beneficial effect generated with the P addition indicated that this nutrient played an important role in alleviating As toxicity in tomato plants. The higher the As concentration in irrigation water the higher the As concentration in plant tissues; most of the As absorbed by plants was accumulated in their roots. Phosphorus application has allowed to reduce As translocation toward tomato berries, enhancing plant P status. These observations may be useful for certain areas of the World, in which As-contaminated waters are used for agricultural purposes. We have studied the uptake and distribution of arsenic (As) and phosphorus (P) in roots, shoots and berries of tomato plants, grown on uncontaminated soil, irrigated with As-contaminated solutions at four concentrations (0, 0.5, 2 and 4 mg L-1), in presence or absence of P fertilization. The biomass of tomato plants decreased with increasing As concentration in irrigation water, especially tomato berries. In addition, the reduction of biomasses was significantly greater in plants non-fertilized with P. The beneficial effect generated with the P addition indicated that this nutrient played an important role in alleviating As toxicity in tomato plants. The higher the As concentration in irrigation water the higher the As concentration in plant tissues; most of the As absorbed by plants was accumulated in their roots. Phosphorus application has allowed to reduce As translocation toward tomato berries, enhancing plant P status. These observations may be useful for certain areas of the World, in which As-contaminated waters are used for agricultural purposes.",
Arsenic,626910,"Effect of sodium arsenite on peripheral lymphocytes in vitro: Individual susceptibility among a population exposed to arsenic through the drinking water Abstract: Arsenic (As) contamination in ground water has affected more than 19 countries. Approximately 36 million people in the Bengal delta alone are exposed to this toxicant via drinking water (>50 µg/l) and are at potential health risk. Chronic ingestion of As via drinking water is associated with occurrence of skin lesions, cancer and other arsenic-induced diseases in West Bengal, India. An in vitro cytogenetic study was performed utilizing chromosomal aberrations (CA) in lymphocytes treated with sodium arsenite (0–5 µM) in six symptomatic (having arsenic-related skin lesions) individuals, six age- and sex-matched As-exposed asymptomatic (no arsenic-related skin lesions) individuals and six control individuals with similar socio-economic status residing in non-affected districts of West Bengal with no evidence of As exposure. The mean As content in nails and hair was 9.61 and 5.23 µg/g in symptomatic, 3.48 and 2.17 µg/g in asymptomatic and 0.42 and 0.33 µg/g in the control individuals, respectively. The main aim of our study was to determine whether genotoxic effects differed in the lymphocytes of the control (no exposure to arsenic), asymptomatic and symptomatic individuals after in vitro treatment with sodium arsenite. Although both the exposed groups had chronic exposure to As through the drinking water, individuals with skin lesions accumulated more As in their nails and hair and excreted less in urine (127.80 versus 164.15 µg/l). The results show that sodium arsenite induced a significantly higher percentage of aberrant cells in the lymphocytes of control individuals than in the lymphocytes of both the exposed groups. Within the two exposed groups As induced higher incidences of CA in the symptomatic than the asymptomatic individuals. These results suggest that asymptomatic individuals have relatively lower sensitivity and susceptibility to induction of genetic damage by As compared with the symptomatic individuals.",
Arsenic,1020042,"Identification of galectin I and thioredoxin peroxidase II as two arsenic-binding proteins in Chinese hamster ovary cells Abstract: In this study, we report the identification of two arsenic-binding proteins from Chinese hamster ovary (CHO) cells. The crude extract derived from CHO and SA7 (arsenic-resistant CHO cells) was applied to a phenylarsine oxide-agarose affinity column, and after extensive washing, the absorbed proteins were eluted with buffers containing 20 mM 2-mercaptoethanol (2-ME) or dithiothreitol (DTT). Three differentially expressed proteins, galectin 1 (Gal-1; in the 2-ME-eluted fraction from CHO cells), glutathione S-transferase P-form (GST-P) and thioredoxin peroxidase II (TPX-II), respectively in the 2-ME- and DTT-eluted fractions from SA7 cells, were identified by partial amino acid sequence analysis after separation by SDS/PAGE. The GST-P protein has been previously shown to facilitate the excretion of sodium arsenite [As(III)] from SA7 cells. TPX II was detected predominately in SA7 cells [routinely cultured in As(III)-containing medium], but not in CHO or SA7N (a revertant of SA7 cells cultured in regular medium) cells. In contrast, Gal-1 was specifically identified in CHO and SA7N cells, but not in SA7 cells. The preferential expression of Gal-1 in CHO cells and TPX-II in SA7 cells was further illustrated by quantitative PCR analysis. The binding of Gal-1 and TPX-II with As(III) was further verified by both co-immunoprecipitation and co-elution of Gal-1 and TPX-II with As(III). It is suggested that Gal-1 and TPX-II are two proteins that serve as high-affinity binding sites for As(III) and thus both may be involved in the biological action of As(III).",
Arsenic,1247787,"Synergistic anti-tumor effects of combination of photodynamic therapy and arsenic compound in cervical cancer cells: In vivo and in vitro studies Abstract: The effects of As(4)O(6) as adjuvant on photodynamic therapy (PDT) were studied. As(4)O(6) is considered to have anticancer activity via several biological actions, such as free radical production and inhibition of VEGF expression. PDT or As(4)O(6) significantly inhibited TC-1 cell proliferation in a dose-dependent manner (P&lt;0.05) by MTT assay. The anti-proliferative effect of the combination treatment was significantly higher than in TC-1 cells treated with either photodynamic therapy or As(4)O(6) alone (62.4 and 52.5% decrease compared to vehicle-only treated TC-1 cells, respectively, P&lt;0.05). In addition, cell proliferation in combination of photodynamic therapy and As(4)O(6) treatment significantly decreased by 77.4% (P&lt;0.05). Cell survival pathway (Naip1, Tert and Aip1) and p53-dependent pathway (Bax, p21(Cip1), Fas, Gadd45, IGFBP-3 and Mdm-2) were markedly increased by combination treatment of photodynamic therapy and As(4)O(6). In addition, the immune response in the NEAT pathway (Ly-12, CD178 and IL-2) was also modulated after combination treatment, suggesting improved antitumor effects by controlling unwanted growth-stimulatory pathways. The combination effect apparently reflected concordance with in vitro data, in restricting tumor growth in vivo and in relation to some common signaling pathways to those observed in vitro. These findings suggest the benefit of combinatory treatment with photodynamic therapy and As(4)O(6) for inhibition of cervical cancer cell growth.",
Arsenic,627378,"Enzymatic methylation of arsenic compounds. V. Arsenite methyltransferase activity in tissues of mice Abstract: With the development of a rapid assay for arsenite methyltransferase (Zakharyan et al., 1995), the specific activity of this critical enzyme for arsenite biotransformation was determined by incubating liver, testis, kidney, or lung cytosol of male B6C3F1 mice with sodium arsenite and S-[methyl-3H]adenosyl-L-methionine and measuring the formation of [methyl-3H]monomethylarsonate. The mean arsenite methyltransferase specific activities (U/mg +/- SEM) measured in these organs were liver, 0.40 +/- 0.06; testis, 1.45 +/- 0.08; kidney, 0.70 +/- 0.06; and lung, 0.22 +/- 0.01. Heretofore, the enzymatic methylation of arsenite has been regarded primarily as a hepatic function. The arsenite methyltransferase specific activity of the testis was 3.6 times greater than that of the liver (p < 0.01) and the specific activity of the kidney was 1.8 times greater than that of the liver (p < 0.05). Additionally, when mice were given arsenate in drinking water for 32 or 91 days at concentrations of 25 or 2500 micrograms As/L, the arsenite methyltransferase activities of liver, testis, kidney, and lung cytosol were not significantly increased in animals receiving either dose of arsenic for either 32 or 91 days compared to controls. No evidence for the induction of arsenite methyltransferase was found under these experimental conditions.",
Arsenic,1352591,In vitro antioxidant study of vegetable oils containing conjugated linolenic acid isomers Abstract: ,
Arsenic,710944,"GT-repeat polymorphism in the heme oxygenase-1 gene promoter and the risk of carotid atherosclerosis related to arsenic exposure Abstract: Arsenic is a strong stimulus of heme oxygenase (HO)-1 expression in experimental studies in response to oxidative stress caused by a stimulus. A functional GT-repeat polymorphism in the HO-1 gene promoter was inversely correlated to the development of coronary artery disease in diabetics and development of restenosis following angioplasty in patients. The role of this potential vascular protective factor in carotid atherosclerosis remains unclear. We previously reported a graded association of arsenic exposure in drinking water with an increased risk of carotid atherosclerosis. In this study, we investigated the relationship between HO-1 genetic polymorphism and the risk of atherosclerosis related to arsenic.<br /><br /> Three-hundred and sixty-seven participants with an indication of carotid atherosclerosis and an additional 420 participants without the indication, which served as the controls, from two arsenic exposure areas in Taiwan, a low arsenic-exposed Lanyang cohort and a high arsenic-exposed LMN cohort, were studied. Carotid atherosclerosis was evaluated using a duplex ultrasonographic assessment of the extracranial carotid arteries. Allelic variants of (GT)n repeats in the 5'-flanking region of the HO-1 gene were identified and grouped into a short (S) allele (< 27 repeats) and long (L) allele (? 27 repeats). The association of atherosclerosis and the HO-1 genetic variants was assessed by a logistic regression analysis, adjusted for cardiovascular risk factors.<br /><br /> Analysis results showed that arsenic's effect on carotid atherosclerosis differed between carriers of the class S allele (OR 1.39; 95% CI 0.86-2.25; p = 0.181) and non-carriers (OR 2.65; 95% CI 1.03-6.82; p = 0.044) in the high-exposure LMN cohort. At arsenic exposure levels exceeding 750 ?g/L, difference in OR estimates between class S allele carriers and non-carriers was borderline significant (p = 0.051). In contrast, no such results were found in the low-exposure Lanyang cohort.<br /><br /> This exploratory study suggests that at a relatively high level of arsenic exposure, carriers of the short (GT)n allele (< 27 repeats) in the HO-1 gene promoter had a lower probability of developing carotid atherosclerosis than non-carriers of the allele after long-term arsenic exposure via ground water. The short (GT)n repeat in the HO-1 gene promoter may provide protective effects against carotid atherosclerosis in individuals with a high level of arsenic exposure.",
Arsenic,1070385,"Effects of lime and compost on earthworm (Eisenia fetida) reproduction in copper and arsenic contaminated soils from the Puchuncaví Valley, Chile Abstract: The Puchuncaví Valley in central Chile has been exposed to atmospheric depositions from a copper smelter. Nowadays, soils in the surrounding area are acidic and contaminated with Cu and As. The objective of this study was to determine the effectiveness of lime and compost for in situ immobilization of trace elements in the soils of the Puchuncaví Valley by using earthworms as bioindicators of toxicity. The lime and compost treatments significantly increased soil pH and decreased the soluble and exchangeable Zn, exchangeable Cu, and free Cu(2+) activity. However, the compost treatment increased soluble Cu, and soluble and exchangeable As. Lime application had no effect on earthworm reproduction in comparison with the unamended control, whereas the application of compost increased cocoon and juvenile production. There was a spatial variability of soil properties within treatments in the field plots. This allowed the identification of which soil properties were actually having an impact on earthworm reproduction. For both cocoon and juvenile production, soil organic matter (SOM) was a positive factor, i.e., more SOM increased cocoon or juvenile production. The toxicity (negative) factor was total soil As. However, total Cu and total As were well correlated (R(2)=0.80, p&lt;0.001), hence some of the trends could have been masked. In summary, compost treatment was effective in improving the quality of soils of Puchuncaví Valley, increasing earthworm reproduction. Future Chilean legislation on maximum permissible concentrations of trace elements in soils should consider SOM content due to its effect on trace element solubility and bioavailability.",
Arsenic,2343513,"Repositioning therapy for thyroid cancer: New insights on established medications Abstract: Repositioning of established non-cancer pharmacotherapeutic agents with well-known activity and side-effect profiles is a promising avenue for the development of new treatment modalities for multiple cancer types. We have analyzed some of the medications with mechanism of action that may have relevance to thyroid cancer (TC). Experimental in vitro and in vivo evidences, as well as results of clinical studies, have indicated that molecular targets for medications currently available for the treatment of mood disorders, sexually transmitted diseases, metabolic disorders, and diabetes may be active and relevant in TC. For instance, the derivatives of cannabis and an anti-diabetic agent, metformin, both are able to inhibit ERK, which is commonly activated in TC cells. We present here several examples of well-known medications that have the potential to become new therapeutics for patients with TC. Repositioning of established medications for the treatment of TC could broaden the scope of current therapeutic strategies. These diverse treatment choices could allow physicians to provide an individualized approach to optimize treatment for patients with TC.",
Arsenic,62166,"Occupational and environmental risks in and around a smelter in northern Sweden: II. Chromosomal aberrations in workers exposed to arsenic Abstract: A significantly increased frequency of chromosomal aberrations was found among arsenic-exposed workers at the Rönnskär smelter in northern Sweden. The correlation between frequency of aberrations and arsenic exposure was rather poor. This may be due to individual variations in susceptibility to damage and to the supposed cocarcinogenic action of arsenic. The results suggested an interaction between smoking and arsenic exposure. A correlation between breaks and gaps was found, which suggests that gaps may be used as indicators of genotoxic agents.",
Arsenic,1339683,"Effect of vitamin E on sperm number and testis histopathology of sodium arsenite-treated rats Abstract: The aims of this study were to investigate the adverse effects of sodium arsenite on the reproductive system of male rats as well as to examine whether vitamin E is able to ameliorate these effects. Adult rats were divided into four groups: 1/ control, 2/ sodium arsenite (8 mg/kg/day), 3/ vitamin E (100 mg/kg/day), and 4/ sodium arsenite +vitamin E group. Treatments were administered orally by gavage for eight weeks. After treatment, body and left testis weights were recorded and the testis was used for the histological analysis. Left cauda epididymis was used to count sperm number. Body and testis weight did not differ among the groups (p>0.05). A significant decrease (p<0.001) in sperm number and mean diameter of seminiferous tubules as well as a significant increase (p<0.001) in the mean diameter of seminiferous tubules' lumen were found in sodium arsenite group compared to those of controls. Sodium arsenite did not affect the morphology and diameter of spermatogonial nucleus (p>0.05). In the sodium arsenite + vitamin E group, vitamin E ameliorated (p<0.001) the adverse effects of sodium arsenite on sperm number as well as the diameters of tubule and lumen. In addition, the treatment of rats with vitamin E alone significantly (p<0.001) increased the diameter of seminiferous tubules and significantly (p<0.001) decreased seminiferous tubules' lumen compared to the control group. Vitamin E appeared to ameliorate the adverse effects of sodium arsenite on epididymal sperm number and some morphometrical parameters of the adult rat testis.",
Arsenic,1337619,"Determination of essential and toxic elements in Cordyceps kyushuensis Kawam by inductively coupled plasma mass spectrometry Abstract: In this study, a total of 20 elements (essential, non-essential and toxic): lithium (Li), sodium (Na), potassium (K), gallium (Ga), magnesium (Mg), zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), vanadium (V), chromium (Cr), nickel (Ni), cobalt (Co), molybdenum (Mo), selenium (Se), barium (Ba), tin (Sn), arsenic (As), lead (Pb) cadmium (Cd) and mercury (Hg) in natural and cultured Cordyceps kyushuensis have been determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Cultured stroma, natural stroma and natural worm were digested by microwave-assisted method before analysis. The proposed ICP-MS method was validated by analyzing a certified reference material (CRM) GBW10015 (spinach). The results of one-way analysis of variance (ANOVA) revealed that the element concentrations in the three kinds of samples were significantly different (p&lt;0.05). Except for Mg, Zn, Cu, the values of other elemental contents were the highest in the stroma of natural C. kyushuensis. In comparison with the worm, the concentrations of determined elements in wild stroma were higher. The remarkable difference of elemental contents between cultured and natural stroma may be caused by distinct growing environment. This finding highlighted the usefulness of ICP-MS elemental analysis and enhanced the value of C. kyushuensis as a candidate for nourishing food based on its composition.",
Arsenic,1034145,Hemangiosarcoma of the liver. Spectrum of morphologic changes and clinical findings Abstract: Analysis of four cases of hemangiosarcoma of the liver and review of the literature indicate that these tumors are either predominantly cystic and fairly well differentiated or are more solid and poorly differentiated. Well-differentiated hemangiosarcomas may resemble peliosis hepatis or other benign conditions. The tumor was associated disseminated intravascular coagulation and fibrinolysis syndrome in one of our cases. One of our patients had received thorium dioxide (Thorotrast) but none seemed to have been exposed to arsenicals or to vinyl chloride.,
Arsenic,1034372,Results of trace arsenic analyses performed by various laboratories Abstract: Personal monitor filter cassettes were spiked with a known amount of arsenic and sent to various laboratories in the public and private sectors for analysis. Results and methods of analysis are discussed in light of proposed arsenic standards. Comparison indicates a high degree of analytical precision and accuracy are lacking.,
Arsenic,1341209,"Aquaporins mediate the chemoresistance of human melanoma cells to arsenite Abstract: The integral membrane channel protein aquaporin (AQP) is aberrantly expressed with oncogenic characteristics in various human cancers. In this study, we analyzed the expression pattern of all subtypes of AQPs, and found that 8 out of 13 AQPs expressed in melanoma cells. To understand the role of aberrant expression of AQP in this disease, we over-expressed AQP3 and AQP9 in human melanoma WM266.4 cells and found that both AQPs significantly increased the chemoresistance of WM266.4 cells to arsenite. Functional studies showed that AQP3 and AQP9 can inhibit cell apoptosis induced by arsenite through down-regulating p53 and up-regulating Bcl-2 and XIAP. Our data suggest the implication of APQ in melanoma progression and that the over-expression of AQP3 and AQP9 contributes to the chemoresistance of melanoma to arsenite.",
Arsenic,1343851,"Population-dynamics of honey-bee nucleus colonies exposed to industrial pollutants Abstract: Nucleus colonies (nucs) of0 honey bees (Apis mellifera L) were evaluated as an alternative to full-size colonies for monitoring pollution impacts. Fifty nucs were deployed at 5 sites along a transect on Vashon Island, Washington. This provided a gradient of exposure to arsenic and cadmium from industrial sources. After 40 d, statisfically significant differences were observed among sites for mean mass and number of bees (P | 0.01), honey yield (P 0.07), and arsenic and cadium content of forager bees (P | 0.001). These findings are discussed in terms of exposure to heavy metals and observed changes in colony dynamics, especially brood rearing and hoarding of pollen, nectar, and honey.",
Arsenic,2088459,"Quantum of optical absorption in two-dimensional semiconductors Abstract: The optical absorption properties of free-standing InAs nanomembranes of thicknesses ranging from 3 nm to 19 nm are investigated by Fourier transform infrared spectroscopy. Stepwise absorption at room temperature is observed, arising from the interband transitions between the subbands of 2D InAs nanomembranes. Interestingly, the absorptance associated with each step is measured to be ?1.6%, independent of thickness of the membranes. The experimental results are consistent with the theoretically predicted absorptance quantum, AQ = ??/nc for each set of interband transitions in a 2D semiconductor, where ? is the fine structure constant and nc is an optical local field correction factor. Absorptance quantization appears to be universal in 2D systems including III-V quantum wells and graphene.",
Arsenic,2347817,"Groundwater quality and geothermal energy. The case of Cerro Prieto Geothermal Field, Mexico Abstract: The influence of the Cerro Prieto Geothermal Field (CPGF) on groundwater quality of the close-by agricultural area was evaluated by means of chemical and isotopic determinations. According to irrigation standards, concentrations of As, Cd, Pb, Crtot, Cr(VI), Cu, Cd, Hg, B in agricultural wells showed the suitability of the water for irrigation. Iron was below irrigation limits in all but one well. However, chloride levels were above those limits in 83 out of 87 collected samples. Isotopic determinations of delta H-2, delta O-18, delta S-34, delta C-13, L and spatial concentration trends of elements related with geothermal brines and toxic metals and metalloids did not indicate an influence of the CPGF to groundwater in the nearby agricultural area. Isotopic values of delta H-2, delta O-18 showed the occurrence of evaporation processes and infiltration of canal's irrigation water to geothermal water reservoirs and to groundwater in the agricultural zone. High chloride concentrations might be associated with these processes.",
Arsenic,1794741,Quantifying modern erosion rates and river-sediment contamination in the Bolivian Andes Abstract: ,
Arsenic,2345629,"Insights from Arsenate Adsorption on Rutile (110): Grazing-Incidence X-ray Absorption Fine Structure Spectroscopy and DFT+U Study Abstract: Insights into the bonding of As(V) at the metal oxide/aqueous interface can further our understanding of its fate and transport in the environment. The motivation of this work is to explore the interfacial configuration of As(V) on single crystal rutile (110) using grazing-incidence X-ray absorption fine structure spectroscopy (GI-XAFS) and planewave density functional calculations with on-site repulsion (DFT+U). In contrast to the commonly considered corner-sharing bidentate binuclear structure, tetrahedral As(V) binds as an edge/corner-sharing tridentate binuclear complex on rutile (110), as evidenced by observation of three As-Ti distances at 2.83, 3.36, and 4.05 Å. In agreement with the GI-XAFS analysis, our DFT+U calculations for this configuration resulted in the lowest adsorption energy among five possible alternatives. In addition, the electron density difference further demonstrated the transfer of charge between surface Ti atoms and O atoms in AsO4. This charge transfer consequently induced the formation of a chemical bond, which is also confirmed by the partial density of states analysis. Our results may shed new light on coupling the GI-XAFS and DFT approaches to explore molecular-scale adsorption mechanisms on single crystal surfaces.",
Arsenic,1508584,"The effect of inorganic arsenic on endothelium-dependent relaxation: Role of NADPH oxidase and hydrogen peroxide Abstract: Chronic arsenic ingestion predisposes to vascular disease, but underlying mechanisms are poorly understood. In the present study we have analyzed the effects of short-term arsenite exposure on vascular function and endothelium-dependent relaxation. Endothelium-dependent relaxations, nitric oxide (NO) and endothelium derived hyperpolarizing factor (EDHF)-type, were studied in rabbit iliac artery and aortic rings using the G protein-coupled receptor agonist acetylcholine (ACh) and by cyclopiazonic acid (CPA), which promotes store-operated Ca2+ entry by inhibiting the endothelial SERCA pump. Production of reactive oxygen species (ROS) in the endothelium of rabbit aortic valve leaflets and endothelium-denuded RIA and aortic rings was assessed by imaging of dihydroethidium. In the iliac artery, exposure to 100?M arsenite for 30min potentiated EDHF-type relaxations evoked by both CPA and ACh. Potentiation was prevented by catalase, the catalase/superoxide dismutase mimetic manganese porphyrin and the NADPH oxidase inhibitor apocynin. By contrast in aortic rings, that exhibited negligible EDHF-type responses, endothelium-dependent NO-mediated relaxations evoked by CPA and ACh were unaffected by arsenite. Arsenite induced apocynin-sensitive increases in ROS production in the aortic valve endothelium, but not in the media and adventitia of the iliac artery and aorta. Our results suggest that arsenite can potentiate EDHF-type relaxations via a mechanism that is dependent on hydrogen peroxide, thus demonstrating that dismutation of the superoxide anion generated by NADPH oxidase can potentially offset loss of NO bioavailability under conditions of reduced eNOS activity. By contrast, selective increases in endothelial ROS production following exposure to arsenite failed to modify relaxations mediated by endogenous NO.",
Arsenic,1936080,"Enhanced HSP30 and HSP70 accumulation in Xenopus cells subjected to concurrent sodium arsenite and cadmium chloride stress Abstract: Heat shock proteins (HSPs) are molecular chaperones that aid in protein folding, translocation and in preventing stress-induced protein aggregation. The present study examined the effect of simultaneous sodium arsenite and cadmium chloride treatment on the pattern of HSP30 and HSP70 accumulation in A6 kidney epithelial cells of the frog, Xenopus laevis. Immunoblot analysis revealed that HSP30 and HSP70 accumulation in concurrent stressor treatments were significantly higher than the sum of HSP30 or HSP70 accumulation in individual treatments. This finding suggested a synergistic action between sodium arsenite and cadmium chloride. KNK437 inhibitor studies indicated that the combined stressor-induced accumulation of HSPs may be regulated, at least in part, at the level of transcription. Immunocytochemistry revealed that simultaneous treatment of cells with the two stressors induced HSP30 accumulation primarily in the cytoplasm in a punctate pattern with some dysregulation of F-actin structure. Increased ubiquitinated protein accumulation was observed with combined sodium arsenite and cadmium chloride treatment compared to individual stressors suggesting an impairment of the ubiquitin proteasome degradation system. The addition of a mild heat shock further enhanced the accumulation of HSP30 and HSP70 in response to relatively low concentrations of sodium arsenite plus cadmium chloride.",
Arsenic,1597368,"Comparative proteomic analysis of rice shoots exposed to high arsenate Abstract: Consumption of arsenic contaminated water and cereals has been a seriously threat to humans all over the world. Rice, as a main cereal crop, can accumulate arsenic more than 10-fold that of in other cereals. To gain a comprehensive understanding of the response of rice subjected to 100?µ? arsenate stress, a comparative proteomic analysis of rice shoots in combination with morphological and biochemical investigations have been performed in this study. The results demonstrated that arsenate suppressed the growth of rice seedlings, destroyed the cellular ultra-structure and changed the homeostasis of reactive oxygen species (ROS). Moreover, a total of 38 differentially displayed proteins, which were mainly involved in metabolism, redox and protein-metabolism, were indentified. The data suggest the arsenic can inhibit rice growth through negatively affecting chloroplast structure and photosynthesis. In addition, up-regulation of the proteins involved in redox and protein metabolism might help the rice to be resistant or tolerant to arsenic toxicity. In general, this study improves our understanding about the rice arsenic responsive mechanism.",
Arsenic,627108,"Low levels of arsenite activates nuclear factor-kB and activator protein-1 in immortalized mesencephalic cells Abstract: Degeneration of dopaminergic neurons is one of the major features of Parkinson's disease. Many redox-active metals such as iron and manganese have been implicated in neuronal degeneration characterized by symptoms resembling Parkinson's disease. Even though, arsenic, which is another redox-active metal, has been shown to affect the central monoaminergic systems, but its potential in causing dopaminergic cell degeneration has not been fully known. Hence, the present study was designed to investigate arsenic signaling especially that is mediated by reactive oxygen species and its effect on early transcription factors in dopamine producing mesencephalic cell line 1RB3AN27. These mesencephalic cells were treated with low concentrations of sodium arsenite (0.1, 0.5, 1, 5, and 10 uM) and incubated for different periods of time (0-4 h). Arsenite was cytotoxic at 5 and 10 uM concentrations only after 72-h incubation period. Arsenite, in a dose-dependent manner, induced generation of reactive oxygen species (ROS) and activation of early transcription factors such as nuclear factor- kB (NF-kB) and activator protein-1 (AP-1) as shown by electro mobility shift assay. Incubation of antioxidants, either N-acetyl-L-cysteine (50 uM) or a-tocopherol (50 uM) with 1 uM arsenite, suppressed ROS generation. Arsenite at 1 uM concentration was sufficient for maximal activation of NF-kB and AP-1 activation. Time kinetics studies showed maximal activation of NF-kB by 1 uM concentration of arsenite was seen at 120 min and correlated with complete degradation of Ik Ba at 60 min. Similarly, maximal activation of AP-1 by 1 uM concentration of arsenite occurred at 120 min. N-acetyl-L-cysteine at 50 uM concentration inhibited arsenite-induced NF- kB and AP-1. In addition, arsenite was shown to induce phosphorylation of extracellular signal regulated kinase (ERK) 1/2 at concentrations of 1 uM and above. These results suggest that arsenite, at low and subcytoxic concentrations, appears to induce oxidative stress leading to activation of early transcription factors whereas addition of antioxidant inhibited the activation of these factors.",
Arsenic,1347846,"Dimethylphosphinato and dimethylarsinato complexes of Sb(III) and Bi(III) and their chemistry Abstract: The reaction of Me2PO2H and Me2AsO2H with SbCl3, BiCl3, and Bi(NO3)3·5H2O gave the complexes Sb(Me2PO2)3, Sb(Me2AsO2)3, (Me2PO2)2Bi-Cl, Bi(Me2AsO2)3, (Me2PO2)2Bi(NO3), and (Me2AsO2)2Bi(NO3)·H2O, respectively. The arsinato complexes did not react with the Lewis bases pyridine, Ph3P, and Ph3As in acetone. The compounds Sb(Me2AsO2)3 and (Me2AsO2)2Bi(NO3)·H2O reacted to a small extent with nicotinic acid in methanol but Bi(Me2AsO2)3 gave (Me2AsO2-BiO) x in good yields. (Me2AsO2)2Bi(NO3)·H2O in methanol quantitatively rearranged to new complexes with the same composition, [(Me2AsO2)2Bi(NO3)·H2O]? and [(Me2AsO2)2Bi(NO3)·H2O]? in the presence of pyridine. With thiophenol in air, Sb(Me2AsO2)3 gave PhSSPh and Me2As-SPh (1:1 mol ratio), (Me2AsO2-SbO) x and some Sb(Me2AsO2)3 was reformed, Bi(Me2AsO2)3 gave (Me2AsO2-BiO) x , PhSSPh, and Me2As-SPh (1:0.6 mol ratio), whereas (Me2AsO2)2Bi(NO3)·H2O quantitatively gave PhSSPh, thus acting as a catalyst for the air oxidation of thiophenol.",
Arsenic,627035,"The molecular mechanisms of arsenic-induced cell transformation and apoptosis Abstract: Arsenic is a well-documented human carcinogen associated with cancers of the skin, lung, liver, and bladder. Interestingly, arsenic has also been used as an effective chemotherapeutic agent in the treatment of certain human cancers. However, the mechanisms by which arsenic induces proliferation of cancer cells or cancer cell death are not well understood. We found that exposure of JB6 P+ cells to low concentrations of arsenic induces cell transformation, whereas higher concentrations of arsenic induce cell apoptosis. Arsenite induces phosphorylation of extracellular signal-regulated protein kinases (Erks) and c-Jun NH(2)-terminal kinases (JNKs). Arsenite-induced Erk activation was markedly inhibited by introduction of dominant-negative Erk2 into cells, whereas expression of dominant-negative Erk2 did not inhibit JNKs or mitogen-activated protein kinase Erk kinase 1/2. Furthermore, arsenite-induced cell transformation was blocked in cells expressing dominant-negative Erk2. In contrast, overexpression of dominant-negative JNK1 increased cell transformation even though it inhibited arsenite-induced JNK activation. Arsenic also induced AP-1 and nuclear factor kappa B (NF-kappaB) activation. Blocking NF-kappaB activation by dominant-negative inhibitory kappa Balpha inhibited arsenic-induced apoptosis and enhanced arsenic-induced cell transformation. Arsenic induced activation of JNKs at a similar dose range that was effective for induction of apoptosis in JB6 cells. In addition, we found that arsenic did not induce p53-dependent transactivation. Similarly, apoptosis induction was not different between p53 wild-type (p53(+/+)) or p53-deficient (p53(-/-)) cells. In contrast, arsenic-induced apoptosis was almost totally blocked by expression of a dominant-negative mutant of JNK. Taken together with previous findings that p53 mutations are involved in approximately 50% of all human cancers and nearly all chemotherapeutic agents kill cancer cells mainly by apoptotic induction, we suggest that arsenic may be a useful agent for the treatment of cancers with p53 mutations. These results suggest that the activation of Erks is required for arsenic-induced cell transformation, whereas the activation of JNKs and NF-kappaB is involved in arsenic-induced apoptosis of JB6 cells.",
Arsenic,1244034,"Arsenic trioxide induces human pulmonary fibroblast cell death via increasing ROS levels and GSH depletion Abstract: Arsenic trioxide (ATO; As2O3) induces apoptotic cell death in various cancer cells including lung cancer via the induction of reactive oxygen species (ROS). However, little is known about the toxicological effects of ATO on normal primary lung cells. Here, we investigated the effects of N-acetyl cysteine (NAC) and vitamin C (well-known antioxidants) or L-buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) on ATO-treated human pulmonary fibroblast (HPF) cells in relation to cell death, ROS and glutathione (GSH). ATO induced growth inhibition and death in HPF cells, accompanied by the loss of mitochondrial membrane potential (MMP; ??m). ATO increased ROS levels including O2•- and GSH depleted cell numbers. NAC attenuated the growth inhibition, death and MMP (??m) loss in ATO-treated HPF cells and also decreased the ROS levels in these cells. However, vitamin C enhanced the growth inhibition, death, MMP (??m) loss and GSH depletion by ATO and even strongly increased mitochondrial O2•- levels in ATO-treated HPF cells. BSO showed a strong increase in ROS levels in ATO-treated HPF cells and intensified the growth inhibition, cell death, MMP (??m) loss and GSH depletion. Moreover, superoxide dismutase (SOD2) or thioredoxin (TXN) siRNAs attenuated HPF cell death by ATO, which was not correlated with ROS and GSH level changes. In conclusion, ATO induced the growth inhibition and death of HPF cells, accompanied by increasing ROS levels and GSH depletion. NAC attenuated HPF cell death by ATO whereas vitamin C and BSO enhanced the death.",
Arsenic,2149187,"DDX3 RNA helicase is required for HIV-1 Tat function Abstract: Host RNA helicase has been involved in human immunodeficiency virus type 1 (HIV-1) replication, since HIV-1 does not encode an RNA helicase. Indeed, DDX1 and DDX3 DEAD-box RNA helicases are known to be required for efficient HIV-1 Rev-dependent RNA export. However, it remains unclear whether DDX RNA helicases modulate the HIV-1 Tat function. In this study, we demonstrate, for the first time, that DDX3 is required for the HIV-1 Tat function. Notably, DDX3 colocalized and interacted with HIV-1 Tat in cytoplasmic foci. Indeed, DDX3 localized in the cytoplasmic foci P-bodies or stress granules under stress condition after the treatment with arsenite. Importantly, only DDX3 enhanced the Tat function, while various distinct DEAD-box RNA helicases including DDX1, DDX3, DDX5, DDX17, DDX21, and DDX56, stimulated the HIV-1 Rev-dependent RNA export function, indicating a specific role of DDX3 in Tat function. Indeed, the ATPase-dependent RNA helicase activity of DDX3 seemed to be required for the Tat function as well as the colocalization with Tat. Furthermore, the combination of DDX3 with other distinct DDX RNA helicases cooperated to stimulate the Rev but not Tat function. Thus, DDX3 seems to interact with the HIV-1 Tat and facilitate the Tat function.",
Arsenic,922780,"Effect of chronic intake of arsenic-contaminated water on blood oxidative stress indices in cattle in an arsenic-affected zone Abstract: This study aimed to determine the hemato-biochemical picture and blood oxidative stress in zebu cattle in an arsenic-contaminated zone. Significant decline in total erythrocyte count, packed cell volume, and total plasma protein was observed in cattle of that area in comparison to uncontaminated zone. There was significant elevation of plasma enzyme activities of both alanine aminotransaminase and aspertate aminotransaminase. Increased corpuscular osmotic fragility also proved to be a mechanism for deviation from normal functioning of erythrocytes. Cattle in the affected zone showed a significantly higher arsenic burden in blood. Those animals further showed decreased superoxide dismutase, catalase activities of erythrocytes, and plasma nitrite level, but increased lipid peroxidation and protein carbonyl level. Our finding concluded that cattle of the arsenic-contaminated zone is suffering from a subclinical form of arsenic toxicity, which is proved through altered hemato-biochemical indices and a certain extent of oxidative stress with higher arsenic concentration in blood.",
Arsenic,454437,"Human exposure to metals through the diet in Tarragona, Spain: Temporal trend Abstract: The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (TI), and vanadium (V) were determined in a number of food items purchased in zones of Tarragona County (Catalonia, Spain) near a hazardous waste incinerator (HWI), which has been operating since 1999. Food samples corresponded to the following groups: meat, fish and seafood, pulses, cereals, vegetables, fruits, tubers, whole milk, yogurt, eggs, and sugar. Be and TI were under their respective limits of detection in all samples. For,the analyzed trace elements, the dietary intake by the general population of Tarragona was 458.5 mu g/d for As, 14.3 mu g/d for Cd, 88.3 mu g/d for Cr, 5.3 mu g/d for Hg, 2421.4 mu g/d for Mn, 138.3 mu g/d for Ni, 44.8 mu g/d for Pb, 34.6 mu g/d for Sn, and 28.9 mu g/d for V. Results were compared with those found in a baseline survey carried out in the same area during the construction of the HWI (1996-1998). In general terms, the dietary intake of metals in 2003 was comparatively similar to those found in the baseline survey. For the most toxic elements (As, Cd, Hg, and Pb), it was under their respective Provisional Tolerable Weekly Intake (PTWI) established by the FAC/WHO.",
Arsenic,710906,"Effect of arsenic on regulatory T cells Abstract: Arsenic (As) affects the function and survival of lymphocytes, and some arsenic compounds exert a relevant antineoplastic effect. We have explored the effect of As on T regulatory cells.<br /><br /> In vitro experiments with peripheral blood mononuclear cells from healthy subjects showed that low concentrations of As tended to increase the number of natural T regulatory (nTreg) lymphocytes, whereas concentrations &gt;5.0 muM had an opposite effect. Furthermore, rats exposed to As showed redistribution of nTreg cells, and As administration to rats with experimental allergic encephalomyelitis increased the levels of nTreg cells in spleen and diminished the severity of this condition. On the other hand, in 47 apparently healthy subjects chronically exposed to As, we found significant inverse correlation between urinary As levels and the number and function of nTreg lymphocytes. Although most of these individuals showed enhanced levels of apoptotic lymphocytes in peripheral blood, with a diminution of mitochondrial membrane potential, no significant correlation between these parameters and urinary As was detected.<br /><br /> Our data indicate that As seems to have a relevant and complex effect on nTreg cells.",
Arsenic,2347769,Preparation of arsenic sulfide thin films for integrated optical elements by spiral bar coating Abstract: We report on the preparation of thin As35S65 films from their amine based solutions by a spiral bar coating technique on flexible PET substrates and the direct writing of subwavelength surface corrugated gratings with a period of 350 nm into these films by excimer laser interference lithography. The structural and optical properties of bar coated As35S65 glass are investigated in detail and compared with those of samples fabricated by vacuum thermal evaporation. The polarization dependent spectral filtering properties of the guided mode resonance devices built by the waveguiding thin films and the surface relief gratings written by a single laser pulse are presented finally. (C) 2014 Optical Society of America,
Arsenic,2149273,"Application of zeolites for radium removal from mine water Abstract: For removal of radium from saline waters in Upper Silesian mines, several methods of purification have been developed. The most efficient one is based on application of barium chloride, which was implemented in full technical scale in two Polish coal mines several years ago. Very good results of purification have been achieved—the removal efficiency exceeding 95 % of the initial activity. Another possibility for the removal of different ions from salty waters and brines is the application of zeolites. We found that technique as a very promising method for removal of not only radium isotopes from mine waters but also other ions (barium, iron, manganese). Treatment of several various water samples has been done to assess the removal efficiency for natural radionuclides. Preliminary results show very good effects for radium isotopes as well as for barium ions. In the paper, a short description of laboratory results of the purification of mine waters with application of synthetic zeolites is presented.",
Arsenic,2149095,"Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy Abstract: We have performed a comparative study of ultrafast charge carrier dynamics in a range of III-V nanowires using optical pump-terahertz probe spectroscopy. This versatile technique allows measurement of important parameters for device applications, including carrier lifetimes, surface recombination velocities, carrier mobilities and donor doping levels. GaAs, InAs and InP nanowires of varying diameters were measured. For all samples, the electronic response was dominated by a pronounced surface plasmon mode. Of the three nanowire materials, InAs nanowires exhibited the highest electron mobilities of 6000 cm² V?¹ s?¹, which highlights their potential for high mobility applications, such as field effect transistors. InP nanowires exhibited the longest carrier lifetimes and the lowest surface recombination velocity of 170 cm s?¹. This very low surface recombination velocity makes InP nanowires suitable for applications where carrier lifetime is crucial, such as in photovoltaics. In contrast, the carrier lifetimes in GaAs nanowires were extremely short, of the order of picoseconds, due to the high surface recombination velocity, which was measured as 5.4 × 10?? cm s?¹. These findings will assist in the choice of nanowires for different applications, and identify the challenges in producing nanowires suitable for future electronic and optoelectronic devices.",
Arsenic,2337134,"Dissolution of arsenic minerals mediated by dissimilatory arsenate reducing bacteria: Estimation of the physiological potential for arsenic mobilization Abstract: The aim of this study was characterization of the isolated dissimilatory arsenate reducing bacteria in the context of their potential for arsenic removal from primary arsenic minerals through reductive dissolution. Four strains, Shewanella sp. OM1, Pseudomonas sp. OM2, Aeromonas sp. OM4, and Serratia sp. OM17, capable of anaerobic growth with As (V) reduction, were isolated from microbial mats from an ancient gold mine. All of the isolated strains: (i) produced siderophores that promote dissolution of minerals, (ii) were resistant to dissolved arsenic compounds, (iii) were able to use the dissolved arsenates as the terminal electron acceptor, and (iii) were able to use copper minerals containing arsenic minerals (e. g., enargite) as a respiratory substrate. Based on the results obtained in this study, we postulate that arsenic can be released from some As-bearing polymetallic minerals (such as copper ore concentrates or middlings) under reductive conditions by dissimilatory arsenate reducers in indirect processes.",
Arsenic,1344479,"A novel cell permeant peptide inhibitor of MAPKAP kinase II inhibits intimal hyperplasia in a human saphenous vein organ culture model Abstract: <strong>OBJECTIVE: </strong>The present study was aimed at developing a new cell-permeant peptide inhibitor (MK2i) of the kinase that phosphorylates and activates heat-shock protein (HSP)27 (MAPKAP kinase II), and evaluating the ability of this peptide to inhibit HSP27 phosphorylation and intimal thickening.<br /><br /><strong>METHODS: </strong>The ability of MK2i to reduce HSP27 phosphorylation and cell migration was evaluated in A7R5 cells stimulated with arsenite or lysophosphatidic acid. Stable isotopic labeling using amino acids in cell culture, in combination with liquid chromatography mass spectrometry, was used to characterize the effect of MK2i on global protein expression in fibroblasts. The effect of MK2i on intimal thickening and connective tissue growth factor expression was evaluated in human saphenous vein (HSV) rings maintained with 30% fetal bovine serum for 14 days by light microscopy and immunoblotting.<br /><br /><strong>RESULTS: </strong>Pretreatment of cells with MK2i (10 ?M) prior to arsenite or lysophosphatidic acid stimulation decreased phosphorylation of HSP27 (36% ± 9% and 33% ± 10%, respectively) compared with control (not pretreated) cells. MK2i also inhibited A7R5 migration, and downregulated the transforming growth factor-induced expression of collagen and fibronectin in keloid cells, two major matrix proteins involved in the development of intimal hyperplasia. Treatment of HSV segments with MK2i enhanced relaxation, reduced HSP27 phosphorylation (40% ± 17%), connective tissue growth factor expression (17% ± 5%), and intimal thickness (48.2% ± 10.5%) compared with untreated segments. On the other hand, treatment with a recombinant fusion protein containing a cell-permeant peptide attached to the HSP27 sequence increased intimal thickness of HSV segments by 48% ± 14%.<br /><br /><strong>CONCLUSION: </strong>Our results suggest that HSP27 may play a role in the development of processes leading to intimal hyperplasia in HSV, and reduction of HSP27 phosphorylation by MK2i may be a potential strategy to inhibit the development of intimal hyperplasia in HSV to prevent the autologous vascular graft failure.",
Arsenic,1354147,"Genetic and demographic responses of mosquitofish (Gambusia holbrooki) populations exposed to mercury for multiple generations Abstract: BIOSIS COPYRIGHT: BIOL ABS. Genetic and demographic responses of mosquitofish were examined after multiple generations of exposure to mercury. Previous studies of acute lethal exposures of mosquitofish to either mercury or arsenic demonstrated a consistent correlation between time to death and genotype at the glucosephosphate isomerase-2 (Gpi-2) locus. A mesocosm study involving mosquitofish populations exposed to mercury for 111 d showed significant female sexual selection and fecundity selection at the Gpi-2 locus. Here the mesocosm study was extended to populations exposed to mercury for several (approx, four) generations. After 2 years, control and mercury-exposed populations met Hardy-Weinberg expectations and showed no evidence of genetic bottlenecks. The mean number of heterozygous loci did not differ significantly between the mercury-exposed and control populations. Significant differences in allele frequen cies at the Gpi-2 locus were observed between the mercury-exposed and control populations. Relative to the initial and control allele frequencies, the Gpi-2100 allele frequency was lower, the Gpi-266 allele frequency increased, but the Gpi-238 allele frequency did not change in mercury-exposed populations. No significant differences were found in standard length, weight, sex ratio, or age class ratio between the control and mercury-exposed populations. Allele frequency changes at the Gpi-2 locus suggest population-level response to chronic mercury exposure. Changes in allele frequency may be useful as indicators of population response to contaminants, provided that the population in question is well understood.",
Arsenic,2149290,"Arsenic speciation in drinking tea samples by hydride generation atomic fluorescence spectrometry Abstract: A simple, low cost and fast speciation method has been developed for the arsenic speciation by hydride generation atomic fluorescence spectrometry (HG-AFS). The contents of arsenic(III) and arsenic(V) was calculated by solving the simultaneous equations obtained at two different experimental conditions, i.e., in the citric acid medium and thiourea-ascorbic acid medium. The total arsenic content was detected after the sample was digested with HNO3 and H2O2 and prepared in thiourea-ascorbic acid medium. The content of the organic arsenic was calculated by subtracting the amount of inorganic arsenic from the total amount of arsenic. The detection limits of this method were 7.0 x 10-2 ?g L-1 for As (III) and 9.5 x 10-2 ?g L-1 for total inorganic arsenic, respectively. This method was applied to the arsenic speciation in six types of Chinese drinking tea without chromatographic and electrophoretic separation.",
Arsenic,2343554,"Adsorption of oxy-anions in the teaching laboratory: An experiment to study a fundamental environmental engineering problem Abstract: Synthesizing and testing bicomposite adsorbents for the removal of environmentally problematic oxy-anions is high on the agenda of research-led universities. Here we present a laboratory module successfully developed at Imperial College London that introduces the advanced undergraduate student in engineering (chemical, civil, earth) and science (chemistry, materials, earth science) to several fundamental principles associated with this research area in a simple, engaging and safe way. This includes (i) the synthesis of inorganic bicomposite sorbents, (ii) the evaluation of the adsorption removal process, and (iii) the analysis of the sorbate; all underpinned by theory. We devise an experiment using phosphate oxyanions and an iron titanium oxide bicomposite sorbent, which is simple to synthesize. The adsorption of phosphate solutions of varying concentration is tested and assessed at pH 5 and 9. Phosphate concentrations at equilibrium are analyzed using UV-vis spectroscopy to plot adsorption isotherms and compare the Langmuir and Freundlich models. This topical introduction to environmental engineering is an excellent opportunity to investigate adsorption processes. The complexity of data interpretation can be tailored to a range of abilities, and the topics addressed in the experiment are relevant starting points for further exploration of environmental geochemistry, pollution control, element transport, and adsorption. We present ready-to-use spreadsheets for the students to facilitate data analysis.",
Arsenic,628021,"Genotoxic effects of arsenic: prevention by functional food-jaggery Abstract: Arsenic contamination in groundwater is global human health hazard. There is no effective remedial action of chronic arsenicosis, however, a well-nourished diet can modulate the onset of adverse health effects and the delayed effect of arsenic in drinking water. In the present work, genotoxic effects induced by arsenic through parenteral administration and ameliorate by jaggery. Chromosomal aberrations were more pronounced in arsenic treated mice, while supplementation of jaggery with arsenic reduced the incidence of the aberrations. The outcome of study showed that Jaggery the natural functional food has the efficiency to encounter the genotoxic effects induced by arsenic.",
Arsenic,1579267,"Combined p19Arf and interferon-beta gene transfer enhances cell death of B16 melanoma in vitro and in vivo Abstract: Approximately 90% of melanomas retain wild-type p53, a characteristic that may help shape the development of novel treatment strategies. Here, we employed an adenoviral vector where transgene expression is controlled by p53 to deliver the p19 alternate reading frame (Arf) and interferon-? (IFN?) complementary DNAs in the B16 mouse model of melanoma. In vitro, cell death was enhanced by combined gene transfer (63.82±15.30% sub-G0 cells); yet introduction of a single gene resulted in significantly fewer hypoploid cells (37.73±7.3% or 36.96±11.58%, p19Arf or IFN?, respectively, P&lt;0.05). Annexin V staining and caspase-3 cleavage indicate a cell death mechanism consistent with apoptosis. Using reverse transcriptase quantitative PCR, we show that key transcriptional targets of p53 were upregulated in the presence of p19Arf, although treatment with IFN? did not alter expression of the genes studied. In situ gene therapy revealed significant inhibition of subcutaneous tumors by IFN? (571±25?mm(3)) or the combination of p19Arf and IFN? (489±124?mm(3)) as compared with the LacZ control (1875±33?mm(3), P&lt;0.001), whereas p19Arf yielded an intermediate result (1053±169?mm(3), P&lt;0.01 vs control). However, only the combination was associated with increased cell death and prolonged survival (P&lt;0.01). As shown here, the combined transfer of p19Arf and IFN? using p53-responsive vectors enhanced cell death both in vitro and in vivo.Cancer Gene Therapy advance online publication, 26 April 2013; doi:10.1038/cgt.2013.23.",
Arsenic,1351759,"Oxidation of sulfur-containing substrates by aboriginal and experimentally designed microbial communities Abstract: Aboriginal and experimental (constructed of pure microbial cultures) communities of acidophilic chemolithotrophs have been studied. The oxidation of elemental sulfur, sodium thiosulfate, and potassium tetrathionate as sole sources of energy has been monitored. The oxidation rate of the experimental community is higher as compared to the aboriginal community isolated from a flotation concentrate of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ore. The degree of oxidation of the mentioned S substrates amounts to 17.91, 68.30, and 93.94% for the experimental microbial community and to 10.71, 56.03, and 79.50% for the aboriginal community, respectively. The degree of oxidation of sulfur sulfide forms in the ore flotation concentrate is 59.15% by the aboriginal microbial community and 49.40% by the experimental microbial community. Despite a higher rate of oxidation of S substrates as a sole source of energy by the experimental microbial community, the aboriginal community oxidizes S substrates at a higher rate in the flotation concentrate of pyrrhotine-containing pyrite-arsenopyrite gold-arsenic sulfide ore, from which it was isolated. Bacterial-chemical oxidation of the flotation concentrate by the aboriginal microbial community allows for the extraction of an additional 32.3% of gold from sulfide minerals, which is by 5.7% larger compared to the yield obtained by the experimental microbial community.",
Arsenic,1329444,"Mitochondrial function in Leydig cell steroidogenesis Abstract: The first and rate-limiting step in the biosynthesis of steroid hormones is the transfer of cholesterol into mitochondria, which is facilitated by the steroidogenic acute regulatory (StAR) protein. Recent studies of Leydig cell function have focused on the molecular events controlling steroidogenesis; however, few studies have examined the importance of the mitochondria. The purpose of this investigation was to determine which aspects of mitochondrial function are necessary for Leydig cell steroidogenesis. MA-10 tumor Leydig cells were treated with 8-bromo-cAMP (cAMP) and site-specific mitochondrial disrupters, pro-oxidants, and their effects on progesterone synthesis, StAR expression, mitochondrial membrane potential (delta psi(m)) and ATP synthesis were determined. Dissipating delta psi(m) with CCCP inhibited progesterone synthesis, even in the presence of newly synthesized StAR protein. The electron transport inhibitor antimycin A significantly reduced cellular ATP, inhibited steroidogenesis, and reduced StAR protein expression. The F0/F1 ATPase inhibitor oligomycin reduced cellular ATP and inhibited progesterone synthesis and StAR protein expression, but had no effect on delta psi(m). Disruption of pH with nigericin significantly reduced progesterone production and StAR protein, but had minimal effects on delta psi(m). Sodium arsenite at low concentrations inhibited StAR protein but not mRNA expression and inhibited progesterone without disrupting delta psi(m). The mitochondrial Ca2+ inhibitor Ru360 also inhibited StAR protein expression. These results demonstrate that delta psi(m), ATP synthesis, delta pH and [Ca2+]mt are all required for steroid biosynthesis, and that mitochondria are sensitive to oxidative stress. These results suggest that mitochondria must be energized, polarized, and actively respiring to support Leydig cell steroidogenesis and alterations in the state of mitochondria may be involved in regulating steroid biosynthesis.",
Arsenic,1017520,"Investigation of biochemical responses of Bacopa monnieri L. upon exposure to arsenate Abstract: Widespread contamination of arsenic (As) is recognized as a global problem due to its well-known accumulation by edible and medicinal plants and associated health risks for the humans. In this study, phytotoxicity imposed upon exposure to arsenate [As(V); 0-250 ?M for 1-7 days] and ensuing biochemical responses were investigated in a medicinal herb Bacopa monnieri L. vis-à-vis As accumulation. Plants accumulated substantial amount of As (total 768 ?g g(-1) dw at 250 ?M As(V) after 7 days) with the maximum As retention being in roots (60%) followed by stem (23%) and leaves (17%). The level of cysteine and total nonprotein thiols (NP-SH) increased significantly at all exposure concentrations and durations. Besides, the level of metalloid binding ligands viz., glutathione (GSH) and phytochelatins (PCs) increased significantly at the studied concentrations [50 and 250 ?M As(V)] in both roots and leaves. The activities of various enzymes viz., arsenate reductase (AR), glutathione reductase (GR), superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), and catalase (CAT) showed differential but coordinated stimulation in leaves and roots to help plants combat As toxicity up to moderate exposure concentrations (50 ?M). However, beyond 50 ?M, biomass production was found to decrease along with photosynthetic pigments and total soluble proteins, whereas lipid peroxidation increased. In conclusion, As accumulation potential of Bacopa may warrant its use as a phytoremediator but if Bacopa growing in contaminated areas is consumed by humans, it may prove to be toxic for health. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011.",
Arsenic,1018157,"High-level exposure to lithium, boron, cesium, and arsenic via drinking water in the Andes of northern Argentina Abstract: Elevated concentrations of arsenic in drinking water are common worldwide, however, little is known about the presence of other potentially toxic elements. We analyzed 31 different elements in drinking water collected in San Antonio de los Cobres and five surrounding Andean villages in Argentina, and in urine of the inhabitants, using ICP-MS. Besides confirmation of elevated arsenic concentrations in the drinking water (up to 210 ?g/L), we found remarkably high concentrations of lithium (highest 1000 ?g/L), cesium (320 ?g/L), rubidium (47 ?g/L), and boron (5950 ?g/L). Similarly elevated concentrations of arsenic, lithium, cesium, and boron were found in urine of the studied women (N=198): village median values ranged from 26 to 266 ?g/L of arsenic, 340 to 4550 ?g/L of lithium, 34 to 531 ?g/L of cesium, and 2980 to 16,560 ?g/L of boron. There is an apparent risk of toxic effects of long-term exposure to several of the elements, and studies on associations with adverse human health effects are warranted, particularly considering the combined, life-long exposure. Because of the observed wide range of concentrations, all water sources used for drinking water should be screened for a large number of elements; obviously, this applies to all drinking water sources globally.",
Arsenic,627480,"Comparative investigations of sodium arsenite, arsenic trioxide and cadmium sulphate in combination with gamma-radiation on apoptosis, micronuclei induction and DNA damage in a human lymphoblastoid cell line Abstract: In the field of radiation protection the combined exposure to radiation and other toxic agents is recognised as an important research area. To elucidate the basic mechanisms of simultaneous exposure, the interaction of the carcinogens and environmental toxicants cadmium and two arsenic compounds, arsenite and arsenic trioxide, in combination with gamma-radiation in human lymphoblastoid cells (TK6) were investigated. Gamma-radiation induced significant genotoxic effects such as micronuclei formation, DNA damage and apoptosis, whereas arsenic and cadmium had no significant effect on these indicators of cellular damage at non-toxic concentrations. However, in combination with gamma-radiation arsenic trioxide induced a more than additive apoptotic rate compared to the sum of the single effects. Here, the level of apoptotic cells was increased, in a dose-dependent way, up to two-fold compared to the irradiated control cells. Arsenite did not induce a significant additive effect at any of the concentrations or radiation doses tested. On the other hand, arsenic trioxide was less effective than arsenite in the induction of DNA protein cross-links. These data indicate that the two arsenic compounds interact through different pathways in the cell. Cadmium sulphate, like arsenite, had no significant effect on apoptosis in combination with gamma-radiation at low concentrations and, at high concentrations, even reduced the radiation-induced apoptosis. An additive effect on micronuclei induction was observed with 1muM cadmium sulphate with an increase of up to 80% compared to the irradiated control cells. Toxic concentrations of cadmium and arsenic trioxide seemed to reduce micronuclei induction. The results presented here indicate that relatively low concentrations of arsenic and cadmium, close to those occuring in nature, may interfere with radiation effects. Differences in action of the two arsenic compounds were identified.",
Arsenic,2278945,"Home environment and prenatal exposure to lead, arsenic and zinc on the neurodevelopment of six-month-old infants living in Chitwan Valley, Nepal Abstract: <strong>BACKGROUND: </strong>We have previously reported the inverse associations between in utero levels of lead (Pb), arsenic (As) (i.e., toxic elements), and neurodevelopmental indicators (i.e., motor and state regulation cluster score) measured by the Brazelton Neonatal Behavioral Assessment Scale, third edition (NBAS III) in this cohort at birth. Using additional follow-up, this study investigated the effects of cord blood levels of Pb, As, and zinc (Zn) (an essential element) and the postnatal environment on the neurodevelopment of 6-month-old infants in Chitwan Valley, Nepal.<br /><br /><strong>METHODS: </strong>In total, 100 mother-infant pairs were recruited from Chitwan District, Nepal. Pb, As, and Zn concentrations in cord blood were measured. Postnatal raising environment (i.e., HOME score or home environment hereafter) was evaluated using the Home Observation for Measurement of Environment (HOME) scale. Neurodevelopment of infants at 6months (n=94) was assessed according to the Bayley Scale of Infant Development, second edition (BSID II). Multivariable regression adjusting for covariates was performed to determine the associations of in utero levels of toxic and essential elements and the home environment with neurodevelopment scores.<br /><br /><strong>RESULTS: </strong>Cord blood levels of Pb, As, and Zn were not associated with any BSID II cluster scores in 6-month-old infants. The total HOME score was positively associated with the Psychomotor Development Index (PDI) score (coefficient=0.59, 95% confidence interval [CI]=0.04 to 1.13).<br /><br /><strong>CONCLUSION: </strong>In this cohort, detrimental effects of in utero Pb and As on neurodevelopmental indicators observed at birth did not persist at 6months of age, while it showed an association between the neurodevelopment and home environment.",
Arsenic,2149346,Arsenic removal by energy-efficient small-scale reverse osmosis units Abstract: ,
Arsenic,1252397,"DNA damage induced in cultured human alveolar (L-132) cells by exposure to dimethylarsinic acid Abstract: Gene damage in cultured human alveolar (L-132) cells induced by exposure to dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenics in mammals, was studied. DNA single-strand breaks and DNA-protein cross-links were induced by the treatment of L-132 cells with 10 mM DMAA. These kinds of damage appeared at 8 hr after start of exposure to DMAA. As regards DNA-protein cross-links, the DNA was found to bind not only to core histone proteins but also linker histone (H1) and nonhistone proteins. Furthermore, the cross-links were formed by the binding to serine or threonine residues of H1 or nonhistone proteins through phosphate moieties of the DNA. The induction of the alkali-labile sites in DNA in DMAA-treated L-132 cells was observed prior to that of DNA single-strand breaks and DNA-protein cross-links. As one of the alkali-labile sites in DNA, we estimated apurinic/apyrimidinic (AP) sites in DNA. The present study suggests that the DNA single-strand breaks and DNA-protein cross-links induced by the treatment of L-132 cells with DMAA occurred via the formation of AP sites in the DNA and that the DNA-protein cross-links were produced by a Schiff-base reaction between amino groups of nuclear proteins and aldehyde groups of AP sites in the DNA and the DNA single-strand breaks, by a beta-elimination reaction on AP sites in the DNA.",
Arsenic,628056,"In utero arsenic exposure induces early onset of atherosclerosis in ApoE-/- mice Abstract: Consumption of arsenic contaminated drinking water has been linked to higher rates of coronary disease, stroke, and peripheral arterial disease. Recent evidence suggests that early life exposures may play a significant role in the onset of chronic adult diseases. To investigate the potential for in utero arsenic exposure to accelerate the onset of cardiovascular disease we exposed pregnant ApoE-knockout (ApoE(-/-)) mice to arsenic in their drinking water and examined the aortic trees of their male offspring for evidence of early disease 10 and 16 weeks after birth. Mice were maintained on normal chow after weaning. ApoE(-/-) mice are a commonly used model for atherogenesis and spontaneously develop atherosclerotic disease. Mice exposed to arsenic in utero showed a >2-fold increase in lesion formation in the aortic roots as well as the aortic arch compared to control mice at both 10 and 16 weeks of age. The mice exposed to arsenic also had a 20-40% decrease in total triglycerides, but no change in total cholesterol, phospholipids and total abundance of VLDL or HDL particles. Subfractionation of VLDL particles showed a decrease in large VLDL particles. In addition, the arsenic-exposed mice showed a vasorelaxation defect in response to acetylcholine suggesting disturbance of endothelial cell signalling. These results indicate that in utero arsenic exposure induces an early onset of atherosclerosis in ApoE(-/-) mice without a hyperlipidemic diet and support the hypothesis that in utero arsenic exposure may be atherogenic in humans.",
Arsenic,2064223,"Arsenite evokes IL-6 secretion, autocrine regulation of STAT3 signaling, and miR-21 expression, processes involved in the EMT and malignant transformation of human bronchial epithelial cells Abstract: Arsenite is an established human carcinogen, and arsenite-induced inflammation contributes to malignant transformation of cells, but the molecular mechanisms by which cancers are produced remain to be established. The present results showed that, evoked by arsenite, secretion of interleukin-6 (IL-6), a pro-inflammatory cytokine, led to the activation of STAT3, a transcription activator, and to increased levels of a microRNA, miR-21. Blocking IL-6 with anti-IL-6 antibody and inhibiting STAT3 activation reduced miR-21 expression. For human bronchial epithelial cells, cultured in the presence of anti-IL-6 antibody for 3days, the arsenite-induced EMT and malignant transformation were reversed. Thus, IL-6, acting on STAT3 signaling, which up-regulates miR-21in an autocrine manner, contributes to the EMT induced by arsenite. These data define a link from inflammation to EMT in the arsenite-induced malignant transformation of HBE cells. This link, mediated through miRNAs, establishes a mechanism for arsenite-induced lung carcinogenesis.",
Arsenic,1018681,"The role of arsenic-thiol interactions in metalloregulation of the ars operon Abstract: The ars operon of the Escherichia coli plasmid R773 that confers arsenical and antimonial resistance is negatively regulated by the ArsR repressor. ArsR residues Cys-32 and Cys-34 were previously identified as involved in induction by arsenite and antimonite, suggesting coordination between As(III) and the two cysteine thiolates. However, in small molecule thiolate-As(III) complexes, arsenic is frequently three-coordinate. A site-directed mutagenic approach was employed in a search for a third arsenic ligand. ArsR proteins with C32G, C34G, and C32G/C34G substitutions were active repressors, but were not inducible in vivo. In vitro, the altered repressor-ars DNA complexes could not be dissociated by inducers. Alteration of Cys-37 and Ser-43, residues located in or near the putative helix-turn-helix DNA-binding region of the protein, had no effect on the inducibility of the operon. While these results indicated that neither the thiolate of Cys-37 nor the hydroxyl oxygen of Ser-43 is required for induction, they did not eliminate either atom as a potential arsenic ligand. Another approach involved reaction with an alternative inducer, phenylarsine oxide, which can form only two coordinations. Phenylarsine oxide was shown to be as effective as or more effective than arsenite or antimonite in induction in vivo. In vitro, the organic arsenical was more effective than either arsenite or antimonite in dissociating the repressor-promoter complex. Thus, two ArsR-arsenic bonds are sufficient for induction. The interaction of ArsR proteins with As(III) was examined using a phenylarsine oxide affinity resin. ArsR proteins containing any two of the three cysteine residues Cys-32, Cys-34, and Cys-37 bound to the resin. Alteration of any two of the three resulted in loss of binding. Arsenic X-ray absorption spectroscopy of ArsR treated stoichiometrically with arsenite confirmed the average arsenic coordination as AsS3 These results suggest that all three cysteine thiolates are arsenic ligands, but binding to only two, the Cys-32 and Cys-34 thiolates, is required to produce the conformational change that results in release of the repressor from the DNA and induction.",
Arsenic,1340295,"Arsenic toxicity of groundwater in parts of the Bengal basin in India and Bangladesh: The role of quaternary stratigraphy and Holocene sea-level fluctuation Abstract: Arsenic toxicity in groundwater in the Ganges delta and some low-lying areas in the Bengal basin is confined to middle Holocene sediments. Dissected terraces and highlands of Pleistocene and early Holocene deposits are free of such problems. Arsenic-rich pyrite or other arsenic minerals are rare or absent in the affected sediments. Arsenic appears to occur adsorbed on iron hydroxide-coated sand grains and clay minerals and is transported in soluble form and co-precipitated with, or is scavenged by, Fe(III) and Mn(IV) in the sediments. It became preferentially entrapped in fine-grained and organic-rich sediments during mid-Holocene sea-level rises in deltaic and some low-lying areas of the Bengal basin. It was liberated subsequently under reducing conditions and mediated further by microbial action. Intensive extraction of groundwater for irrigation and application of phosphate fertilizer possibly triggered the recent release of arsenic to groundwater. This practice has induced groundwater flow, mobilizing phosphate derived from fertilizer, as well as from decayed organic matter, which has promoted the growth of sediment biota and aided the further release of arsenic. However, the environment is not sufficiently reducing to mobilize iron and arsenic in groundwater in the Ganges floodplains upstream of Rajmahal. Thus, arsenic toxicity in the groundwater of the Bengal basin is caused by its natural setting, but also appears to be triggered by recent anthropogenic activities.",
Arsenic,2343457,"Arsenite oxidation and removal driven by a bio-electro-Fenton process under neutral pH conditions Abstract: The iron-catalyzed oxidation of arsenite (As(III)) associated with Fenton or Fenton-like reactions is one of the most efficient arsenic removal methods. However, the conventional chemical or electro-Fenton systems for the oxidation of As(III) are only efficient under acid conditions. In the present study, a cost-effective and efficient bio-electro-Fenton process was performed for As(III) oxidation in a dual-chamber microbial fuel cell (MFC) under neutral pH conditions. In such a system, the Fenton reagents, including H2O2 and Fe(II), were generated in situ by microbial-driven electro-reduction of O2 and ?-FeOOH, respectively, without an electricity supply. The results indicated that the process was capable of inducing As(III) oxidation with an apparent As(III) depletion first-order rate constant of 0.208h(-1). The apparent oxidation current efficiency was calculated to be as high as 73.1%. The ?-FeOOH dosage in the cathode was an important factor in determining the system performance. Fourier-transform infrared spectroscopy (FT-IR) analysis indicated that As(V) was bound to the solid surface as a surface complex but not as a precipitated solid phase. The mechanism of bio-E-Fenton reaction for As(III) oxidation was also proposed. The bio-electro-Fenton system makes it potentially attractive method for the detoxification of As(III) from aqueous solution.",
Arsenic,1348340,"Modulation of the stress-induced synthesis of hsp27 and alpha B-crystallin by cyclic AMP in C6 rat glioma cells Abstract: The possible participation of cyclic AMP in the stress-induced synthesis of two small stress proteins, hsp27 and alpha B-crystallin, in C6 rat glioma cells was examined by specific immunoassays, western blot analysis, and northern blot analysis. When C6 cells were exposed to arsenite (50-100 microM for 1 h) or heat (42 degrees C for 30 min), expression of hsp27 and alpha B-crystallin was stimulated, with levels of the two proteins reaching a maximum after 10-16 h of culture. Induction of hsp27 was markedly enhanced when cells were exposed to arsenite in the presence of isoproterenol (20 microM) or epinephrine (20 microM) but not in the presence of phenylephrine. The stimulatory effects of isoproterenol and epinephrine were blocked completely by propranolol, an antagonist of beta-adrenergic receptors. Cholera toxin (2 micrograms/ml), forskolin (20 microM), and dibutyryl cyclic AMP (2.5 mM), all of which are known to increase intracellular levels of cyclic AMP, also stimulated the arsenite- or heat-induced accumulation of hsp27. Treatment of cells with each of these modulators alone did not result in the induction of hsp27. The level of hsp70 in C6 cells, as estimated by western blot analysis, was also enhanced by arsenite or heat stress. However, induction of hsp70 by stress was barely stimulated by isoproterenol. By contrast, induction of alpha B-crystallin by heat or arsenite stress was suppressed when isoproterenol, cholera toxin, forskolin, or dibutyryl cyclic AMP was present during the stress period. Northern blot analysis of the expression of mRNAs for hsp70, hsp27, and alpha B-crystallin showed that the modulation of the stress-induced accumulation of the three hsps by the various agents was regulated at the level of the corresponding mRNA. These results indicate that stress responses of hsp70, hsp27, and alpha B-crystallin in C6 rat glioma cells are regulated differently and, moreover, that when the level of cyclic AMP increases in cells, the response to stress of hsp27 is stimulated but that of alpha B-crystallin is suppressed.",
Arsenic,1347947,"Effect of sodium arsenite on heme metabolism in cultured chick embryo hepatocytes Abstract: We had previously reported that low concentrations of sodium arsenite (1-5 microM) decreased the induction of cytochrome P450 CYP1A and CYP2H in cultured chick embryo hepatocytes in parallel with increases in heme oxygenase. However, in those studies exogenous heme did not prevent the decrease in CYPs. In this study, we investigated the effect of arsenite on the synthesis and degradation of heme. Arsenite had no effect on induction of 5-aminolevulinic acid synthase mRNA or activity. Arsenite, at concentrations from 1 to 25 microM, had no effect on protoporphyrin synthesis from 5-aminolevulinic acid and did not increase the accumulation of other porphyrins, indicating that the enzymes in the pathway between 5-aminolevulinic acid synthase and ferrochelatase were unaffected by arsenite. Synthesis of heme from radioactive 5-aminolevulinic acid was slightly decreased (less than 20%) by 2.5 microM arsenite, a concentration that decreased induction of CYP1A and CYP2H by greater than 50%. Rates of biliverdin formation and degradation of exogenous heme were not different in cultures treated simultaneously with arsenite and heme or with heme alone. However, arsenite treatment increased biliverdin formation from heme synthesized from added 5-aminolevulinic acid by 60% and decreased the endogenous heme content of the cells by 30%. Our results suggest that although 2.5 microM arsenite induced heme oxygenase four- to sixfold, this had no effect on degradation of exogenous heme. Degradation of heme synthesized from 5-aminolevulinic acid was increased but this did not affect the regulatory heme pool.",
Arsenic,8698,"Influence of arsenic on selenium metabolism and glutathione peroxidase activity in rats Abstract: Arsenic accumulated to the greatest extent in blood followed in decreasing order by kidney, hair and liver in rats fed with various levels of arsenic. Within the intracellular fractions of the liver, arsenic accumulated to the greatest extent in the nuclear fraction, followed by cytosol, mitochondria and microsomes in decreasing order. Increasing arsenic significantly increased the deposition of 75Se-selenite in heart and testis but had no effect in blood, liver, spleen or kidney and significantly increased the excretion of 75Se in feces with a concomitant decrease in urinary excretion. Within the hepatic intracellular fractions, arsenic significantly altered only the 75Se content of the microsomes. Arsenic had no effect upon the glutathione peroxidase activities in blood, kidney or testes, but depressed this activity and the stable selenium content in liver.",
Arsenic,627913,"Protein oxidative damage in arsenic induced rat brain: Influence of DL-?-lipoic acid Abstract: A body of evidence has accumulated implicating free radical generation and reaction of arsenic with protein thiols in the biochemical and molecular mechanisms of arsenic toxicity. Brain readily undergoes oxidative damage, so it is important to determine whether arsenic-induced changes in rat brain may be associated with oxidative events. An increase in oxidative stress may contribute to the development of protein damage in rat brain. Present experiments were performed to study the effect of arsenic (sodium arsenite, 100 ppm mixed in drinking water) on protein oxidation and further to demonstrate the potential of dl-alpha-lipoic acid (70 mg/kg body weight) against arsenic-induced changes in different anatomic regions (cortex, striatum, cerebellum, hypothalamus and hippocampus) of the brain of male Wistar rats. We report here that arsenic treated rats had a significantly higher level of oxidised protein as assessed by increased carbonyl residues and decreased protein thiols (protein sulfhydryls) as compared to control rats in all five regions studied, with the most notable changes occurring in the cortex, striatum and hippocampus. Coadministration of lipoic acid along with arsenic resulted in reversal of the arsenic induced trends in carbonyl and sulfhydryl concentrations. The results of the study showed, lipoic acid treatment reduces oxidative protein damage in arsenic intoxicated rat brain regions, which is associated with its antioxidant activity that combines free radical scavenging and metal chelating properties.",
Arsenic,1018458,"Arsenic compound-induced increases in glutathione levels in cultured Chinese hamster V79 cells and mechanisms associated with changes in gamma-glutamylcysteine synthetase activity, cystine uptake and utilization of cysteine Abstract: Increases in the glutathione (GSH) level in cultured Chinese hamster V79 cells incubated with arsenic compounds were investigated in terms of changes in the activity of gamma-glutamylcysteine synthetase (gamma-GCS), rate of cystine uptake, and utilization of cysteine. Arsenite at subtoxic concentrations caused a marked increase of the GSH level at 8 h after addition and then declined. Increase in the GSH level caused by arsenite was associated with an increase in the rate of cystine uptake, but not in gamma-GCS activity. Increase in the rate of uptake of cystine was attributed mainly to an increase in the utilization of cysteine in the synthesis of GSH. Dimethylarsinic acid (DMAA) also caused an increase in the GSH level in a time- and concentration-dependent manner. Increase in the GSH level was accompanied by increases in gamma-GCS activity and in the uptake of cystine. DMAA caused a reduction in the rate of utilization of cysteine for protein synthesis while enhancing the rate of cysteine utilization for GSH synthesis. Cycloheximide inhibited increases in gamma-GCS activity caused by DMAA and in the rate of cystine uptake caused by arsenite and DMAA. The cystine transport system is suggested to be induced by arsenite and DMAA with gamma-GCS induced in cells incubated with DMAA. Among the arsenic compounds, methylarsonic acid (MAA) was not effective in causing an increase in the GSH level. Accordingly, increases in the GSH level caused by arsenite and DMAA may be specific phenomena in which the cells responded to the arsenicals by increasing the GSH level.",
Arsenic,2345731,"Relationship between arsenic skin lesions and the age of natural menopause Abstract: <strong>BACKGROUND: </strong>Chronic exposure to arsenic is associated with neoplastic, cardiovascular, endocrine, neuro-developmental disorders and can have an adverse effect on women's reproductive health outcomes. This study examined the relationship between arsenic skin lesions (a hallmark sign of chronic arsenic poisoning) and age of natural menopause (final menopausal period) in populations with high levels of arsenic exposure in Bangladesh.<br /><br /><strong>METHODS: </strong>We compared menopausal age in two groups of women - with and without arsenic skin lesions; and presence of arsenic skin lesions was used as an indicator for chronic arsenic exposure. In a cross-sectional study, a total of 210 participants were randomly identified from two ongoing studies- participants with arsenic skin lesions were identified from an ongoing clinical trial and participants with no arsenic skin lesions were identified from an ongoing cohort study. Mean age of menopause between these two groups were calculated and compared. Multivariable linear regression was used to estimate the relationship between the status of the arsenic skin lesions and age of natural menopause in women.<br /><br /><strong>RESULTS: </strong>Women with arsenic skin lesions were 1.5 years younger (p &lt;0.001) at the time of menopause compared to those without arsenic skin lesions. After adjusting with contraceptive use, body mass index, urinary arsenic level and family history of premature menopause, the difference between the groups' age at menopause was 2.1 years earlier (p &lt;0.001) for respondents with arsenic skin lesions.<br /><br /><strong>CONCLUSIONS: </strong>The study showed a statistically significant association between chronic exposure to arsenic and age at menopause. Heavily exposed women experienced menopause two years earlier than those with lower or no exposure.",
Arsenic,1015708,"Trichosanthes dioica fruit ameliorates experimentally Induced arsenic toxicity in male albino rats through the alleviation of oxidative stress Abstract: The present work was focused to evaluate the ameliorative property of aqueous extract of Trichosanthes dioica fruit (AQ T. dioica fruit) against arsenic-induced toxicity in male Wistar albino rats. AQ T. dioica fruit was administered orally to rats at 50 and 100 mg/kg body weight for 20 consecutive days prior to oral administration of sodium arsenite (10 mg/kg) for 10 days. Then the rats were sacrificed for the evaluation of body weights, organ weights, hematological profile, serum biochemical profile, and hepatic and renal antioxidative parameters viz. lipid peroxidation, reduced and oxidized glutathione, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and DNA fragmentation. Pretreatment with AQ T. dioica fruit at both doses markedly and significantly normalized body weights, organ weights, hematological profiles, and serum biochemical profile in arsenic-treated animals. Further, AQ T. dioica fruit pretreatment significantly modulated all the aforesaid hepatic and renal biochemical perturbations and reduced DNA fragmentation in arsenic-intoxicated rats. Therefore, from the present findings, it can be concluded that T. dioica fruit possessed remarkable value in amelioration of arsenic-induced hepatic and renal toxicity, mediated by alleviation of arsenic-induced oxidative stress by multiple mechanisms in male albino rats.",
Arsenic,62035,"Survey of antimony workers: Mortality 1961-1992 Abstract: The mortality of a census population and a prospective cohort of men employed on an antimony smelter in the north east of England was followed up from 1961-1992. The workers studied were exposed to a variety of agents including antimony and its oxides, arsenic and arsenic oxides, sulphur dioxide, and polycyclic aromatic hydrocarbons. The regional mortality rates were used to calculate expected deaths and a group of zircon sand workers employed on the site were used as a comparison group. For the census population of men working on the smelter before 1961 a significant increase in deaths from lung cancer was found (32 observed v 14.7 expected, P &lt; 0.001). A similar excess was seen among maintenance men (12 observed v 5.3 expected P = 0.016). No such excess was found in the cohort recruited after 1960 (5 observed v 9.2 expected, maintenance workers 3 observed v 2.8 expected). There was evidence of a minimum latency period of around 20 years between first exposure and death from lung cancer. No evidence was found for a correlation between length of time worked and mortality from lung cancer. The results show that an increased risk of lung cancer existed in the workers employed before 1961, but it was not possible to attribute this excess to any particular agent. Mortality analysed by five year calendar periods of first exposure show a lessening of effect after 1955. Although the power of the study is clearly less for more recent periods of exposure the absence of any excess in the population after 1960 is encouraging.",
Arsenic,1508645,"Comparison of the metal accumulation capacity between the acanthocephalan Pomphorhynchus laevis and larval nematodes of the genus Eustrongylides sp. infecting barbel (Barbus barbus) Abstract: <strong>UNLABELLED: </strong>ABSTRACT:<br /><br /><strong>BACKGROUND: </strong>Metal uptake and accumulation in fish parasites largely depends on the parasite group with acanthocephalans showing the highest accumulation rates. Additionally, developmental stage (larvae or adult) as well as parasite location in the host are suggested to be decisive factors for metal bioconcentration in parasites. By using barbel (Barbus barbus) simultaneously infected with nematode larvae in the body cavity and adult acanthocephalans in the intestine, the relative importance of all of these factors was compared in the same host.<br /><br /><strong>METHODS: </strong>Eleven elements Arsenic (As), Cadmium (Cd), Cobalt (Co), Copper (Cu), Iron (Fe), Manganese (Mn), Lead (Pb), Selenium (Se), Tin (Sn), Vanadium (V) and Zinc (Zn) were analyzed in barbel tissues (muscle, intestine, liver) as well as in their acanthocephalan parasites Pomphorhynchus laevis and the larval nematode Eustrongylides sp. (L4) using inductively coupled plasma mass spectrometry (ICP-MS).<br /><br /><strong>RESULTS: </strong>Nine elements were detected in significantly higher levels in the parasites compared to host tissues. The element composition among parasites was found to be strongly dependent on parasite taxa/developmental stage and localization within the host. Intestinal acanthocephalans accumulated mainly toxic elements (As, Cd, Pb), whereas the intraperitoneal nematodes bioconcentrated essential elements (Co, Cu, Fe, Se, Zn).<br /><br /><strong>CONCLUSION: </strong>Our results suggest that in addition to acanthocephalans, nematodes such as Eustrongylides sp. can also be applied as bioindicators for metal pollution. Using both parasite taxa simultaneously levels of a wide variety of elements (essential and non essential) can easily be obtained. Therefore this host-parasite system can be suggested as an appropriate tool for future metal monitoring studies, if double infected fish hosts are available.",
Arsenic,1171979,"Toxicogenomic analysis of aberrant gene expression in liver and liver tumors induced by transplacental exposure to inorganic arsenic in mice Abstract: Arsenic is a known human carcinogen. We have reported that brief exposure of pregnant mice to arsenite in the drinking water induces hepatocellular carcinoma (HCC) in the offspring. In this prior work, adult male mice, which were the offspring of dams exposed to sodium arsenite (85 ppm as arsenic) in the drinking water from gestation day 8 to 18, showed a 61% rate of HCC while control animals showed a spontaneous rate of 12%. Liver tumor or surrounding pathologically normal liver tissue samples were taken at necropsy and quick frozen for later use. In the present study, total RNA was extracted from these liver samples, and subjected to microarray and quantitative RT-PCR analysis. Among 600 genes, arsenic-induced HCC showed a higher rate of aberrant gene expression (greater than 2-fold increase or decrease, 31% of all genes tested) than spontaneous tumors (20% of all genes tested). Overexpression of estrogen receptor-alpha, cyclin D1, c-myc and suppression of p27 was associated with arsenic exposure. Expression of alpha-fetoprotein and downregulation of syndecan-1, markers for aggressiveness of HCC, were seen only in arsenic-induced tumors. The non-tumorous hepatic tissue of animals transplacentally exposed to arsenic also showed various significant alterations in the expression of genes associated with cell proliferation, oxidative stress, signal transduction, DNA damage/repair, and hepatic biotransformation. Real time RT-PCR largely confirmed these findings (with a 75% accordance among 32 selected genes from microarray). These aberrantly expressed genes could be important in arsenic carcinogenesis. This genomic analysis revealed aberrant gene expression patterns associated with transplacental arsenic carcinogenesis, indicating that arsenic can alter gene expression long after a brief exposure during gestation. This study points towards the importance of protecting pregnant women in areas where arsenic exposure is common.",
Arsenic,2064219,"Arsenic waste management: A critical review of testing and disposal of arsenic-bearing solid wastes generated during arsenic removal from drinking water Abstract: Water treatment technologies for arsenic removal from groundwater have been extensively studied due to widespread arsenic contamination of drinking water sources. Central to the successful application of arsenic water treatment systems is the consideration of appropriate disposal methods for arsenic-bearing wastes generated during treatment. However, specific recommendations for arsenic waste disposal are often lacking or mentioned as an area for future research and the proper disposal and stabilization of arsenic-bearing waste remains a barrier to the successful implementation of arsenic removal technologies. This review summarizes current disposal options for arsenic-bearing wastes, including landfilling, stabilization, cow dung mixing, passive aeration, pond disposal, and soil disposal. The findings from studies that simulate these disposal conditions are included and compared to results from shorter, regulatory tests. In many instances, short-term leaching tests do not adequately address the range of conditions encountered in disposal environments. Future research directions are highlighted and include establishing regulatory test conditions that align with actual disposal conditions and evaluating nonlandfill disposal options for developing countries.",
Arsenic,1017645,"Arsenic accumulation and thiol status in lichens exposed to As(V) in controlled conditions Abstract: Thalli of epiphytic lichen Hypogymnia physodes (L.) Nyl. and terricolous Cladonia furcata (Huds.) Schrad., collected from an area with background arsenic concentrations, were exposed to 0, 0.1, 1 and 10 microg mL(-1) arsenate (As(V)) solutions for 24 h. After exposure they were kept in the metabolically active state for 0, 24 and 48 h in a growth chamber. In the freeze dried samples glutathione (GSH), glutathione disulphide (GSSG), cysteine (Cys) and cystine were analysed and induction of phytochelatin (PC) synthesis measured by reversed-phase high-performance liquid chromatography in combination with fluorescence detection or UV spectrometry. Total arsenic content in thalli was measured by instrumental neutron activation analysis (INAA). In H. physodes, which contained higher amounts of arsenic compared to C. furcata, total glutathione content significantly decreased in samples exposed to 10 microg mL(-1) As(V), whereas in C. furcata a significant increase was observed. In both species PC synthesis was induced in thalli exposed to 10 microg mL(-1).",
Arsenic,1351065,"Arsenic and cadmium in the marine macroalgae (Porphyra yezoensis and Laminaria Japonica) - forms and concentrations Abstract: Total arsenic, inorganic arsenic (iAs), total cadmium concentrations and chemical forms of cadmium were analysed in Porphyra yezoensis collected monthly from January to April in 2011 and in Laminaria Japonica collected monthly from March to July in 2010. Results showed that total As concentrations in P. yezoensis were much lower than those in L. Japonica. The iAs concentrations in both macroalgae were all below the maximum limit according to the legislation in China, while total Cd concentrations in all samples of P. yezoensis exceeded the maximum limit. The percentage of iAs to total As decreased in both macroalgae with the time. The results provide important information showing that both macroalgae are able to metabolise inorganic arsenic to organic forms. Thus both macroalgae have evolved arsenic resistance which is linked to the capability of metabolising toxic inorganic arsenic. In addition, the results suggest that the transformation rate of arsenate to organic arsenic in both algae increases with the growth and metabolic rate that increase with elevated environmental temperature. Temperatures rise from January to April in Jiangsu province and from March to July in Liaoning Province. Most Cd was associated with pectates and protein (extractable by 1 M NaCl) in both algae, and only a small percentage of the Cd was inorganic (extractable by 80% ethanol). The Cd chemical forms have no obvious relationship with the time in both algae.",
Arsenic,1246947,"Prioritization of chemical pollutants emitted by facilities for the management of household waste in France, based on their non-carcinogenic impacts on public health Abstract: Background : Health impact assessments provide information for policies governing municipal waste treatment facilities (incinerators, landfills, sorting/recycling centres, composting centres, and green waste methane production facilities). Currently, only the standard pollutants (PMX, NO2, SO2, O-3), carcinogens (As, Cd, BaP), and Pb and Hg (for their neurotoxic effects) have been evaluated. Other chemical emissions have been excluded because of the lack of dose-response functions. The purpose of the AMESTIS project is to develop such functions for the non-cancer effects of pollutants emitted during waste treatment. To set the priorities for this work, this paper develops a ranking of these pollutants in terms of their potential health impact. Objective : To identify in waste treatment facility emissions the pollutants with the highest potential for non-cancer health impacts. Methods : The pollutants were inventoried from French studies, position papers and regulations. Two methods for prioritization were tested, one qualitative and one quantitative. The first method assigned points to each pollutant based on information available about the frequency and quantity of its emissions and other relevant aspects of its toxicological profile. The scoring system gives priority to emission rates (frequency and quantity) and to toxic effects on the cardiovascular, nervous, respiratory, and reproductive systems as well as on fetal development. The second method considers the ""hazard ratio'' for each pollutant, based on its emission rate and available toxicological reference values. After analysing the correlation between the results of both methods a ranking is proposed. Results : About 250 pollutants have been identified in emissions from municipal waste treatment facilities. Quantitative data on their toxicity and emission rates are available for 98. Forty-three are found in incinerator emissions, 88 in landfill biogas, 41 in composting facilities, and 58 in green waste methane production facilities; 20 are common to the four types of waste treatments. These pollutants include 45 VOCs, 19 metals, 8 PAHs, 8 pesticides, 6 inorganic compounds, 4 BTEX, 4 aldehydes, and 4 persistent organic pollutants. Correlation of the results of the two ranking systems is poor. Independently of the ranking method, the top 10 pollutants in the overall ranking include 7 metals (As, Cd, Mn, Cr, Hg, Ni, Co), 2 organic compounds (naphthalene, benzene) and one inorganic compound (hydrogen sulfide). Lead and dioxins, pollutants that have attracted much attention in this field, are ranked in 19th and 27th place, respectively. If we limit the study to emissions from incinerators only, lead and dioxins move up to 10th and 12th place. Discussion/conclusion : Regardless of ranking method, the results show that metals present the greatest potential for non-cancer health impacts. Here we select arsenic, cadmium, chromium, manganese, mercury and nickel for the development of non-carcinogenic dose-response functions. Furthermore, municipal waste treatment facility emissions in France are still relatively poorly known, in particular those of VOCs from incinerators and sorting/recycling centers. The creation of a national database with detailed results from monitoring of emissions of each facility would fill this knowledge gap. The regulatory emission limits should be sulemented by values for organic compounds (BTEX, PAHs, VOCs), and the limits for metals should be unbundled to avoid mixing elements of very different toxic properties and hence with heterogeneous effects on public health.",
Arsenic,1017110,"A bacterium that can grow by using arsenic instead of phosphorus Abstract: Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. Although these six elements make up nucleic acids, proteins, and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions. Here, we describe a bacterium, strain GFAJ-1 of the Halomonadaceae, isolated from Mono Lake, California, that is able to substitute arsenic for phosphorus to sustain its growth. Our data show evidence for arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins. Exchange of one of the major bio-elements may have profound evolutionary and geochemical importance.",
Arsenic,1356865,"Integrative Analysis Of Genome-Wide Gene Expression And Pathway Mapping In Mouse Embryonic Fibroblast (MEF) Exposed To Cadmium, Arsenic And Methylmercury: Induction Of Oxidative Stress, Disruption Of Ubiquitin-Proteasome System And Cell Cycle Regulation Abstract: Environmental and occupational exposures to heavy metals including Methylmercury (MeHg), arsenic (As) and cadmium (Cd) pose significant health risks to humans. Although many toxicological impacts have been associated with these metals exposure, the underlying mechanisms of toxicity have not been clearly defined. We conducted gene expression array analysis by using the CodeLink Mouse UniSet 10K oligonucleotide-based platform to explore the gene alterations caused by metals. We treated mouse embryonic fibroblast cells (MEF) with environmentally relevant doses of MeHg (2.5?M), Cd (5.0?M) and As (5.0 ?M) for 24 h. A classical proteasome inhibitor, MG132 (0.5 ?M), was included to compare its pattern of gene expression with metals to determine if disruption of ubiquitinproteasome system (UPS) is a critical mechanism of metal-induced toxicity. The doses selected were consistent with our previous studies where minimal impacts were observed on stress signaling and apoptotic pathways. Following normalization of the array data, we have employed multi-level analysis tools to explore the data, including group comparisons, cluster analysis and gene annotations analysis using MAPPFinder. Furthermore we applied knowledge-based pathway mapping of our gene expression data by using GenMAPP. Using these integrated approaches, we identified significant alterations in UPS, antioxidant and phase II enzymes, DNA repair and damage pathway and cell cycle regulation pathways across the three metals. The results suggest the critical roles of above pathways in metal-induced toxicity. Furthermore, this study demonstrated that the integration of toxicogenomic and knowledge-based pathway mapping is a powerful approach to elucidate molecular mechanism of toxicity.",
Arsenic,627512,"Arsenic toxicity is enzyme specific and its affects on ligation are not caused by the direct inhibition of DNA repair enzymes Abstract: The molecular mechanism of arsenic toxicity is believed to be due to the ability of arsenite [As(III)] to bind protein thiols. Numerous studies have shown that arsenic is cytotoxic at micromolar concentrations. Micromolar As can also induce chromosomal damage and inhibit DNA repair. The mechanism of arsenic-induced genotoxicity is very important because arsenic is a human carcinogen, but not a mutagen, and there is a need to establish recommendations for safe levels of As in the environment. We have measured the dose-response for arsenic inhibition of several purified human DNA repair enzymes, including DNA polymerase beta, DNA ligase I and DNA ligase III and have found that most enzymes, even those with critical SH groups, are very insensitive to As. Many repair enzymes are activated by millimolar concentrations of As(III) and/or As(V). Only pyruvate dehydrogenase, one of eight purified enzymes examined so far, is inhibited by micromolar arsenic. In contrast to the purified enzymes, treatment of human cells in culture with micromolar arsenic produces a significant dose-dependent decrease in DNA ligase activity in nuclear extracts from the treated cells. However, the ligase activity in extracts from untreated cells is no more sensitive to arsenic than the purified enzymes. Our results show that direct enzyme inhibition is not a common toxic effect of As and that only a few sensitive enzymes are responsible for arsenic-induced cellular toxicity. Thus, arsenic-induced co-mutagenesis and inhibition of DNA repair is probably not the result of direct enzyme inhibition, but may be an indirect effect caused by As-induced changes in cellular redox levels or alterations in signal transduction pathways and consequent changes in gene expression.",
Arsenic,1597436,"A pilot study of seafood consumption and exposure to mercury, lead, cadmium and arsenic among infertile couples undergoing in vitro fertilization (IVF) Abstract: This cross-sectional pilot study was conducted to assess environmental exposures to toxic elements through seafood consumption, among infertile couples undergoing in vitro fertilization (IVF). Twenty-five women and 15 men completed a questionnaire, and provided biologic specimens for quantification of Hg, Pb, Cd, and As using ICP-MS. Consumption of 'mollusks' and 'shellfish' are associated with increased blood Hg. Other seafood consumption predicts blood Pb, and urine Cd and As. Though limited by small numbers and the cross-sectional design, these results suggest that consumption of specific seafood items increases exposure to toxic elements in couples undergoing IVF.",
Arsenic,627871,"Depletion of securin increases arsenite-induced chromosome instability and apoptosis via a p53-independent pathway Abstract: Arsenic is a pathologic factor of cardiovascular diseases and cancers; nevertheless, it also acts as an anticancer agent effective on acute promyelocytic leukemia and multiple myeloma. Securin, a proposed proto-oncogene, regulates cell proliferation and tumorigenesis. However, roles of securin on the arsenic-induced cell cycle arrest and apoptosis remain unknown. In this study, the effects of sodium arsenite on the expression of securin in two tissue types of cell lines, the vascular endothelial and colorectal epithelial cells, were investigated. Arsenite (8-16 microM, 24 h) increased the cytotoxicity, apoptosis, and growth inhibition in both endothelial and epithelial cells. The levels of phospho-CDC2 (threonine-161), CDC2, and cyclin B1 proteins were decreased, and the G2/M fractions were increased by arsenite. Concomitantly, arsenite markedly diminished the securin protein expression and induced the abnormal sister chromatid separation. The depletion of securin proteins increased the induction of mitotic arrest, aberrant chromosome segregation, and apoptosis after arsenite treatment. p53, a tumor suppressor protein, balances the cell survival and apoptosis. Arsenite raised the levels of phospho-p53 (serine-15) and p53 (DO-1) proteins in both the securin-wild-type and -null cells. The p53-functional cells were more susceptible than the p53-mutational cells to arsenite on the cytotoxicity and apoptosis. Besides, arsenite decreased the levels of securin proteins to a similar degree in both the p53-functional and -mutational cells. Together, it is the first time to demonstrate that the inhibition of securin expression induced by arsenite increases the chromosomal instability and apoptosis via a p53-independent pathway.",
Arsenic,2088511,"Effects of arsenic on modification of promyelocytic leukemia (PML): PML responds to low levels of arsenite Abstract: Inorganic arsenite (iAs(3+)) is a two-edged sword. iAs(3+) is a well-known human carcinogen; nevertheless, it has been used as a therapeutic drug for acute promyelocytic leukemia (APL), which is caused by a fusion protein comprising retinoic acid receptor-? and promyelocytic leukemia (PML). PML, a nuclear transcription factor, has a RING finger domain with densely positioned cysteine residues. To examine PML-modulated cellular responses to iAs(3+), CHO-K1 and HEK293 cells were each used to establish cell lines that expressed ectopic human PML. Overexpression of PML increased susceptibility to iAs(3+) in CHO-K1 cells, but not in HEK293 cells. Exposure of PML-transfected cells to iAs(3+) caused PML to change from a soluble form to less soluble forms, and this modification of PML was observable even with just 0.1?M iAs(3+) (7.5ppb). Western blot and immunofluorescent microscopic analyses revealed that the biochemical changes of PML were caused at least in part by conjugation with small ubiquitin-like modifier proteins (SUMOylation). A luciferase reporter gene was used to investigate whether modification of PML was caused by oxidative stress or activation of antioxidant response element (ARE) in CHO-K1 cells. Modification of PML protein occurred faster than activation of the ARE in response to iAs(3+), suggesting that PML was not modified as a consequence of oxidative stress-induced ARE activation.",
Arsenic,2337205,"Comparison of methods used to calculate typical threshold values for potentially toxic elements in soil Abstract: The environmental quality of land can be assessed by calculating relevant threshold values, which differentiate between concentrations of elements resulting from geogenic and diffuse anthropogenic sources and concentrations generated by point sources of elements. A simple process allowing the calculation of these typical threshold values (TTVs) was applied across a region of highly complex geology (Northern Ireland) to six elements of interest; arsenic, chromium, copper, lead, nickel and vanadium. Three methods for identifying domains (areas where a readily identifiable factor can be shown to control the concentration of an element) were used: k-means cluster analysis, boxplots and empirical cumulative distribution functions (ECDF). The ECDF method was most efficient at determining areas of both elevated and reduced concentrations and was used to identify domains in this investigation. Two statistical methods for calculating normal background concentrations (NBCs) and upper limits of geochemical baseline variation (ULBLs), currently used in conjunction with legislative regimes in the UK and Finland respectively, were applied within each domain. The NBC methodology was constructed to run within a specific legislative framework, and its use on this soil geochemical data set was influenced by the presence of skewed distributions and outliers. In contrast, the ULBL methodology was found to calculate more appropriate TTVs that were generally more conservative than the NBCs. TTVs indicate what a &quot;typical&quot; concentration of an element would be within a defined geographical area and should be considered alongside the risk that each of the elements pose in these areas to determine potential risk to receptors.",
Arsenic,1020465,"Environmental arsenic exposure from a coal-burning power plant as a potential risk factor for nonmelanoma skin carcinoma: Results from a case-control study in the district of Prievidza, Slovakia Abstract: To investigate the risk of arsenic exposure from a coal-burning power plant in Slovakia on nonmelanoma skin cancer (NMSC) development, a 1996-1999 population-based case-control study was conducted with 264 cases and 286 controls. Exposure assessment was based on residential history and annual emissions (Asres1, Asres2) and on nutritional habits and arsenic content in food (Asnut1, Asnut2). Asres1 was assessed as a function of the distance of places of residence to the plant. Asres2 additionally considered workplace locations. Asnut1 was used to calculate arsenic uptake by weighting food frequencies with arsenic concentrations and annual consumption of food items. Asnut2 additionally considered consumption of local products. Age- and gender-adjusted risk estimates for NMSC in the highest exposure category (90th vs. 30th percentile) were 1.90 (95% confidence interval (CI): 1.39, 2.60) for Asres1, 1.90 (95% CI: 1.38, 2.62) for Asres2, 1.19 (95% CI: 0.64, 2.12) for Asnut1, and 1.83 (95% CI: 0.98, 3.43) for Asnut2. No interaction was found between arsenic exposure and dietary and residential data. Other plant emissions could have confounded the distance-based exposure variables. Consumption of contaminated vegetables and fruits could be confounded by the protective effects of such a diet. Nevertheless, the authors found an excess NMSC risk for environmental arsenic exposure.",
Arsenic,1016554,"Arsenic exposure in the wine growing industry in ten French departments Abstract: <strong>OBJECTIVES: </strong>This study investigated exposure to arsenic, a carcinogenic fungicide used in wine growing.<br /><br /><strong>METHODS: </strong>The first phase compared urinary arsenic excretion of controls and workers exposed at the end of application. The second phase measured the increase in urinary arsenic excretion during the first day of use.<br /><br /><strong>RESULTS: </strong>A significant increase in urinary arsenic excretion was observed in arsenic applicators during the first phase. Urinary arsenic concentrations exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) exposure index in one-third of the workers. The second phase showed a significant increase in urinary arsenic excretion by the first day of application. A closed tractor cabin provided a protective effect, but the efficacy of individual protection equipment was not demonstrated.<br /><br /><strong>CONCLUSION: </strong>This study showed the difficulties of achieving the effective protection of arsenic applicators and has led to the banning of the use of arsenic in French vineyards.",
Arsenic,628128,"Groundwater arsenic contamination in Bangladesh and West Bengal, India Abstract: Nine districts in West Bengal, India, and 42 districts in Bangladesh have arsenic levels in groundwater above the World Health Organization maximum permissible limit of 50 microg/L. The area and population of the 42 districts in Bangladesh and the 9 districts in West Bengal are 92,106 km(2) and 79.9 million and 38,865 km(2) and 42.7 million, respectively. In our preliminary study, we have identified 985 arsenic-affected villages in 69 police stations/blocks of nine arsenic-affected districts in West Bengal. In Bangladesh, we have identified 492 affected villages in 141 police stations/blocks of 42 affected districts. To date, we have collected 10,991 water samples from 42 arsenic-affected districts in Bangladesh for analysis, 58,166 water samples from nine arsenic-affected districts in West Bengal. Of the water samples that we analyzed, 59 and 34%, respectively, contained arsenic levels above 50 microg/L. Thousands of hair, nail, and urine samples from people living in arsenic-affected villages have been analyzed to date; Bangladesh and West Bengal, 93 and 77% samples, on an average, contained arsenic above the normal/toxic level. We surveyed 27 of 42 districts in Bangladesh for arsenic patients; we identified patients with arsenical skin lesions in 25 districts. In West Bengal, we identified patients with lesions in seven of nine districts. We examined people from the affected villages at random for arsenical dermatologic features (11,180 and 29,035 from Bangladesh and West Bengal, respectively); 24.47 and 15.02% of those examined, respectively, had skin lesions. After 10 years of study in West Bengal and 5 in Bangladesh, we feel that we have seen only the tip of iceberg.",
Arsenic,734979,"Monomethylarsonous acid produces irreversible events resulting in malignant transformation of a human bladder cell line following 12 weeks of low-level exposure Abstract: Arsenic is a known human bladder carcinogen; however, the mechanisms underlying arsenical-induced bladder carcinogenesis are not understood. Previous research has demonstrated that exposure of a nontumorigenic human urothelial cell line, UROtsa, to 50 nM monomethylarsonous acid (MMA(III)) for 52 weeks resulted in malignant transformation. To focus research on the early mechanistic events leading to MMA(III)-induced malignancy, the goal of this research was to resolve the critical period in which continuous MMA(III) exposure (50 nM) induces the irreversible malignant transformation of UROtsa cells. An increased growth rate of UROtsa cells results after 12 weeks of MMA(III) exposure. Anchorage-independent growth occurred after 12 weeks with a continued increase in colony formation when 12-week exposed cells were cultured for an additional 12 or 24 weeks without MMA(III) exposure. UROtsa cells as early as 12 weeks MMA(III) exposure were tumorigenic in severe combined immunodeficiency mice with tumorigenicity increasing when 12-week exposed cells were cultured for an additional 12 or 24 weeks in the absence of MMA(III) exposure. To assess potential underlying mechanisms associated with the early changes that occur during MMA(III)-induced malignancy, DNA methylation was assessed in known target gene promoter regions. Although DNA methylation remains relatively unchanged after 12 weeks of exposure, aberrant DNA methylation begins to emerge after an additional 12 weeks in culture and continues to increase through 24 weeks in culture without MMA(III) exposure, coincident with the progression of a tumorigenic phenotype. Overall, these data demonstrate that 50 nM MMA(III) is capable of causing irreversible malignant transformation in UROtsa cells after 12 weeks of exposure. Having resolved an earlier timeline in which MMA(III)-induced malignant transformation occurs in UROtsa cells will allow for mechanistic studies focused on the critical biological changes taking place within these cells prior to 12 weeks of exposure, providing further evidence about potential mechanisms of MMA(III)-induced carcinogenesis.",
Arsenic,2278472,"Ultrasonic assisted arsenate adsorption on solvothermally synthesized calcite modified by goethite, ?-MnO2 and goethite/?-MnO2 Abstract: A highly porous calcium carbonate (calcite; sorbent 1) was used as a support for modification with ?-FeOOH (calcite/goethite; sorbent 2), ?-MnO2 (calcite/?-MnO2; sorbent 3) and ?-FeOOH/?-MnO2 (calcite/goethite/?-MnO2; sorbent 4) in order to obtain a cheap hybrid materials for simple and effective arsenate removal from aqueous solutions. The adsorption ability of synthesized adsorbents was studied as a function of functionalization methods, pH, contact time, temperature and ultrasonic treatment. Comparison of the adsorptive effectiveness of synthesized adsorbents for arsenate removal, under ultrasound treatment and classical stirring method, has shown better performance of the former one reaching maximum adsorption capacities of 1.73, 21.00, 10.36 and 41.94 mg g(-1), for sorbents 1-4, respectively. Visual MINTEQ equilibrium speciation modeling was used for prediction of pH and interfering ion influences on arsenate adsorption.",
Arsenic,1339139,"Trophic status and metal bioaccumulation differences in multiple fish species exposed to coal ash-associated metals Abstract: On December 22, 2008 a dike containing coal fly ash from the Tennessee Valley Authority Kingston Fossil Plant near Kingston Tennessee USA failed and resulted in the largest coal ash spill in U.S. history. Coal ash, a by-product of coal combustion, is known to contain multiple contaminants of concern, including arsenic and selenium. The purpose of this study was to investigate species differences in the bioaccumulation of arsenic and selenium and potential factors contributing to these differences (i.e., trophic dynamics and gut pH) in the vicinity of the Kingston coal ash spill. Elevated levels of arsenic and selenium were observed in various tissues of largemouth bass, white crappie, bluegill and redear sunfish from sites associated with the Kingston coal ash spill. Highest concentrations of selenium were found in redear sunfish with liver concentrations as high as 24.83mg/kg dry weight and ovary concentrations up to 10.40mg/kg dry weight at coal ash-associated sites. Investigations into the gut pH and trophic dynamics of redear sunfish and bluegill demonstrated a large difference in the gut physiology between these two species. Redear sunfish stomach and intestinal pH was found to be 1.1 and 0.16 pH units higher than in bluegill, respectively. In addition, fish from coal ash-associated sites showed enrichment differences ((15)N and (13)C) compared to no ash sites, indicating differences in food web dynamics between sites. These results imply the incorporation of coal ash-associated compounds into local food webs and/or a shift in diet at ash sites compared to the no ash reference sites. Based on these results, further investigation into a broader food web at ash-associated sites is warranted.",
Arsenic,2337190,"Predicting Geogenic Arsenic Contamination in Shallow Groundwater of South Louisiana, United States Abstract: Groundwater contaminated with arsenic (As) threatens the health of more than 140 million people worldwide. Previous studies indicate that geology and sedimentary depositional environments are important factors controlling groundwater As contamination. The Mississippi River delta has broadly similar geology and sedimentary depositional environments to the large deltas in South and Southeast Asia, which are severely affected by geogenic As contamination and therefore may also be vulnerable to groundwater As contamination. In this study, logistic regression is used to develop a probability model based on surface hydrology, soil properties, geology, and sedimentary depositional environments. The model is calibrated using 3286 aggregated and binary-coded groundwater As concentration measurements from Bangladesh and verified using 78 As measurements from south Louisiana. The model's predictions are in good agreement with the known spatial distribution of groundwater As contamination of Bangladesh, and the predictions also indicate high risk of As contamination in shallow groundwater from Holocene sediments of south Louisiana. Furthermore, the model correctly predicted 79% of the existing shallow groundwater As measurements in the study region, indicating good performance of the model in predicting groundwater As contamination in shallow aquifers of south Louisiana.",
Arsenic,1017218,"Candidate single nucleotide polymorphism markers for arsenic responsiveness of protein targets Abstract: Arsenic is a toxic metalloid that causes skin cancer and binds to cysteine residues-a property that could be used to infer arsenic responsiveness of a target protein. Non-synonymous Single Nucleotide Polymorphisms (nsSNPs) result in amino acid substitutions and may alter arsenic binding with cysteine residues. Thus, the objective of this investigation was to identify and analyze nsSNPs that lead to substitutions to or from cysteine residues as an indication of increased or decreased arsenic responsiveness. We hypothesize that integration of data on molecular impacts of nsSNPs and arsenic-gene relationships will identify nsSNPs that could serve as arsenic responsiveness markers. We have analyzed functional and structural impacts data for 5,811 nsSNPs linked to 1,224 arsenic-annotated genes. In addition to the identified candidate nsSNPs for increased or reduced arsenic responsiveness, we observed i) a nsSNP that results in the breakage of a disulfide bond, as candidate marker for reduced arsenic responsiveness of KLK7, a secreted serine protease participate in normal shedding of the skin; and ii) 6 pairs of vicinal cysteines in KLK7 protein that could be binding sites for arsenic. In summary, our analysis identified non-synonymous SNPs that could be used to evaluate responsiveness of a protein target to arsenic. In particular, an epidermal expressed serine protease with crucial function in normal skin physiology was prioritized on the basis of abundance of vicinal cysteines for further research on arsenic-induced keratinocyte carcinogenesis.",
Arsenic,2347808,Group VA polyesters containing thiodiglycolic acid-synthesis and preliminary cancer activity Abstract: The interfacial condensation between the salt of thiodiglycolic acid and the Group V dihalides produces the corresponding polyesters in moderate to good yield in 15 secs and less. The products are tacky to glassy. Infrared spectroscopy shows the formation of the M-O linkage with bands present derived from both reactants. The geometry about the metal is predominately non-bridging. MALDI MS shows ion fragment clusters to two repeat units with ion fragment clusters consistent with the formation of the M-O-C(O)- linkage. The arsenic polymer exhibits outstanding inhibition of the AsPC-1 adenocarcinoma pancreatic cancer cell line. Both the arsenic and antimony polymer show good inhibition of the PC-3 prostate cancer cell line. The antimony polymer shows good inhibition of both the MDA-MB-231 breast cancer cells that are estrogen-independent and estrogen receptor negative and the MCF-7 breast cancer cells that are an estrogen receptor (ER) positive cancer cell line.,
Arsenic,1015855,"Long-term impact of arsenic in drinking water on bladder cancer health care and mortality rates 20 years after end of exposure Abstract: <strong>PURPOSE: </strong>In this study we assessed bladder cancer health care and mortality trends in recent decades in a well studied arsenic exposed area in Northern Chile.<br /><br /><strong>MATERIALS AND METHODS: </strong>Arsenic levels in the affected region were obtained for the last 60 years, and correlated with bladder cancer hospital discharge and mortality rates in recent decades.<br /><br /><strong>RESULTS: </strong>Bladder cancer hospital discharge rates were significantly higher in the affected region (peak RR 3.6, 95% CI 3.0-4.7). Mortality rates for bladder cancer showed a trend of increase during the period analyzed, reaching peak mortality rates of 28.4 per 100,000 for men and 18.7 per 100,000 for women in the last 10 years. Poisson regression models showed an increased mortality risk in the studied region compared to the rest of the country until the present for men (IRR 5.3, 95% CI 4.8-5.8) and women (IRR 7.8, 95% CI 7.0-8.7). Mean age at cancer specific death was significantly lower in the exposed region (69.6 years, 95% CI 68.4-70.7 vs 73.7 years, 95% CI 73.3-74.2, p &lt;0.01).<br /><br /><strong>CONCLUSIONS: </strong>Exposure to arsenic is related to a significant need for bladder cancer health care and to high mortality rates even 20 years after having controlled arsenic levels in drinking water. Affected individuals should be aware of the significant impact of this ecological factor. Further research is required to identify strategies for the management of bladder cancer in arsenic exposed populations.",
Arsenic,656648,"Characterization of the intestinal absorption of arsenate, monomethylarsonic acid, and dimethylarsinic acid using the Caco-2 cell line Abstract: Many toxicological studies have been conducted with arsenic species in target organ cell lines. However, although epithelial gastrointestinal cells constitute the first barrier to the absorption of contaminants, studies using intestinal cells are scarce. The present study examines absorption through the intestinal epithelium of the pentavalent arsenic species most commonly found in foods [arsenate, As(V); monomethylarsonic acid, MMA(V); and dimethylarsinic acid, DMA(V)], using the Caco-2 cell line as a model. Different concentrations (1.3-667.6 microM) and culture conditions (media, pH, addition of phosphates, and treatment with ethylenediaminetetraacetic acid) were evaluated to characterize such transport. The apparent permeabilities indicate that the methylated species show low absorption, whereas As(V) is a compound with moderate absorption. The kinetic study shows only a saturable component for MMA(V) transport in the range of concentrations assayed. The existence of paracellular transport was shown for all of the species, with greater significance in the case of the methylated forms. As(V) absorption was inhibited by 10 mM phosphate, and a phosphate transporter therefore could take part in intestinal absorption. Acidification of the medium (pH 5.5) resulted in a marked increase in As(V) and DMA(V) permeability (4-8 times, respectively) but not in MMA(V) permeability. This makes it necessary to consider the possible existence of absorption in the proximal intestine and even in the stomach, where the environment is acidic; alternatively, an H(+)-dependent transporter may be involved. The results obtained constitute the basis for future research on the mechanisms involved in the intestinal absorption of arsenic and its species, a decisive step in relation to their toxic action.",
Arsenic,2279020,"Modified composites based on mesostructured iron oxyhydroxide and synthetic minerals: A potential material for the treatment of various toxic heavy metals and its toxicity Abstract: The composites of mesostructured iron oxyhydroxide and/or commercial synthetic zeolite were investigated for use in the removal of toxic heavy metals, such as cadmium, copper, lead and arsenic, from aqueous solution. Four types of adsorbents, dried alginate beads (DABs), synthetic-zeolite impregnated beads (SZIBs), meso-iron-oxyhydroxide impregnated beads (MIOIBs) and synthetic-zeolite/meso-iron-oxyhydroxide composite beads (SZMIOIBs), were prepared for heavy metal adsorption tests. Laboratory experiments were conducted to investigate the removal efficiencies of cations and anions of heavy metals and the possibility of regenerating the adsorbents. Among these adsorbents, the MIOIBs can simultaneously remove cations and anions of heavy metals; they have high adsorption capacities for lead (60.1 mgg-1) and arsenic (71.9 mgg-1) compared with other adsorbents, such as DABs (158.1 and 0.0 mgg-1), SZIB (42.9 and 0.0 mgg-1) and SZMIOIB (54.0 and 5.9 mgg-1) for lead and arsenic, respectively. Additionally, the removal efficiency was consistent at approximately 90%, notwithstanding repetitive regeneration. The characteristics of meso-iron-oxyhydroxide powder were confirmed by X-ray diffraction, Brunauer-Emmett-Teller and transmission electron microscopy. We also performed a comparative toxicity study that indicated that much lower concentrations of the powdered form of mesostructured iron oxyhydroxide had stronger cytotoxicity than the granular form. These results suggest that the granular form of meso iron oxyhydroxide is a more useful and safer adsorbent for heavy metal treatment than the powdered form. This research provides promising results for the application of MIOIBs as an adsorbent for various heavy metals from wastewater and sewage.",
Arsenic,1508612,"Concordant hypermethylation of intergenic microRNA genes in human hepatocellular carcinoma as new diagnostic and prognostic marker Abstract: Epigenetic inactivation by aberrant DNA methylation has been reported for many microRNA genes in various human malignancies. However, relatively little is known about microRNA gene methylation in hepatocellular carcinoma (HCC). Therefore, a systematic screen for identification of aberrantly hypermethylated microRNA genes in HCC was initiated. The methylation status of 39 intergenic CpG island associated microRNA genes was analyzed in HCC cell lines (n?=?7), immortalized hepatocytes (n?=?2) and normal liver samples (n?=?5). Subsequently, 13 differentially methylated microRNA genes were analyzed in primary human HCC samples (n?=?40), benign liver tumors (n?=?15) and the adjacent liver tissues employing pyrosequencing. Expression of microRNA genes was measured using quantitative real-time polymerase chain reaction (RT-PCR). In addition, DNA methylation and expression of microRNA genes were measured after DNMT1 knockdown or DNMT inhibition. Aberrant hypermethylation and concomitant reduction in expression of intergenic microRNA genes is a frequent event in human HCC: hsa-mir-9-2 (23%), hsa-mir-9-3 (50 %), hsa-mir-124-1 (20%), hsa-mir-124-2 (13%), hsa-mir-124-3 (43%), hsa-mir-129-2 (58%), hsa-mir-596 (28%) and hsa-mir-1247 (38%). Altogether, it affects 90% of the HCC specimens under study. MicroRNA gene methylation is not found in hepatocellular adenoma (n?=?10) and focal nodular hyperplasia (n?=?5). DNMT1 knockdown or DNMT inhibition reduced microRNA gene methylation and stimulated expression. In primary human HCC specimens hypermethylation and expression of microRNA genes showed an inverse correlation. Concordant hypermethylation of three or more microRNA genes is a highly specific marker for the detection of HCC and for poor prognosis.",
Arsenic,2347593,"Contamination assessment of arsenic and heavy metals in a typical abandoned estuary wetland-a case study of the Yellow River Delta Natural Reserve Abstract: Coastal and estuarine areas are often polluted by heavy metals that result from industrial production and agricultural activities. In this study, we investigated the concentration trait and vertical pattern of trace elements, such as As, Cd, Ni, Zn, Pb, Cu, and Cr, and the relationship between those trace elements and the soil properties in coastal wetlands using 28 profiles that were surveyed across the Diaokouhe Nature Reserve (DKHNR). The goal of this study is to investigate profile distribution characteristics of heavy metals in different wetland types and their variations with the soil depth to assess heavy metal pollution using pollution indices and to identify the pollution sources using multivariate analysis and sediment quality guidelines. Principal component analysis, cluster analysis, and pollution level indices were applied to evaluate the contamination conditions due to wetland degradation. The findings indicated that the concentration of trace elements decreased with the soil depth, while Cd increases with soil depth. The As concentrations in reed swamps and Suaeda heteroptera surface layers were slightly higher than those in other land use types. All six heavy metals, i.e., Ni, Cu, As, Zn, Cr, and Pb, were strongly associated with PC1 (positive loading) and could reflect the contribution of natural geological sources of metals into the coastal sediments. PC2 is highly associated with Cd and could represent anthropogenic sources of metal pollution. Most of the heavy metals exhibited significant positive correlations with total concentrations; however, no significant correlations were observed between them and the soil salt and soil organic carbon. Soil organic carbon exhibited a positive linear relationship with Cu, Pb, and Zn in the first soil layer (0-20 cm); As, Cr, Cu, Ni, Pb, and Zn in the second layer (20-40 cm); and As, Cr, Cu, Ni, Pb, and Zn in the third layer (40-60 cm). Soil organic carbon exhibited only a negative correlation with Cd (P?&lt;?0.05), in the second and third layers. As, Cr, Cu, Ni, Pb, and Zn exhibited lower geoaccumulation index values (I geo values), which averaged less than 0 in the three soil layers, this finding indicates that the soils have remained unpolluted by these heavy metals. The mean concentrations of these trace elements were lower than Class I criteria. The degradation wetland restoration suggestions have also been provided in such a way as to restore the reserved flow path of the Yellow River. The results that are associated with trace element contamination would be helpful in providing scientific directions to restore wetlands across the world.",
Arsenic,2345673,"Multicenter Cohort Study to Assess the Impact of a Silver-Alloy and Hydrogel-Coated Urinary Catheter on Symptomatic Catheter-Associated Urinary Tract Infections Abstract: <strong>PURPOSE:: </strong>The purpose of this study was to determine the effect of a silver-alloy hydrogel catheter on symptomatic catheter-associated urinary tract infections (CAUTIs).<br /><br /><strong>DESIGN:: </strong>Multicenter before-after non-randomized cohort study.<br /><br /><strong>SUBJECTS AND SETTING:: </strong>Seven acute care hospitals ranging in size from 124 to 607 beds participated in this study. The study population included adult patients with a positive urine culture 2 or more days after admission, who underwent Foley catheterization.<br /><br /><strong>METHODS:: </strong>Catheter-associated urinary tract infection surveillance was conducted at each hospital for at least 3 months during the use of a standard catheter and 3 months during the use of the silver-alloy hydrogel catheter. Both the National Healthcare Safety Network (NHSN) surveillance and a clinical definition of CAUTI were used for rate calculation.<br /><br /><strong>RESULTS:: </strong>A 47% relative reduction in the CAUTI rate was observed with the silver-alloy hydrogel catheter compared to the standard catheter when both infection definitions were used (0.945/1000 patient days vs 0.498/1000 patient days) (odds ratio = 0.53; P &lt; .0001; 95% CI: 0.45-0.62). When only NHSN-defined CAUTIs were considered, a 58% relative reduction occurred in the silver-alloy hydrogel period (0.60/1000 patient days vs 0.25/1000 patient days) (odds ratio = 0.42; P &lt; .0001; 95% CI: 0.34-0.53). Antimicrobial days for CAUTIs decreased from 1165 (standard catheter period) to 406 (silver-alloy hydrogel period).<br /><br /><strong>CONCLUSIONS:: </strong>Use of a silver-alloy hydrogel urinary catheter reduced symptomatic CAUTI occurrences as defined by both NHSN and clinical criteria.This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivitives 3.0 License, where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.",
Arsenic,628053,"Developmental consequences of in utero sodium arsenate exposure in mice with folate transport deficiencies Abstract: Previous studies have demonstrated that mice lacking a functional folate binding protein 2 gene (Folbp2-/-) were significantly more sensitive to in utero arsenic exposure than were the wild-type mice similarly exposed. When these mice were fed a folate-deficient diet, the embryotoxic effect of arsenate was further exacerbated. Contrary to expectations, studies on 24-h urinary speciation of sodium arsenate did not demonstrate any significant difference in arsenic biotransformation between Folbp2-/- and Folbp2+/+ mice. To better understand the influence of folate pathway genes on arsenic embryotoxicity, the present investigation utilized transgenic mice with disrupted folate binding protein 1 (Folbp1) and reduced folate carrier (RFC) genes. Because complete inactivation of Folbp1 and RFC genes results in embryonic lethality, we used heterozygous animals. Overall, no RFC genotype-related differences in embryonic susceptibility to arsenic exposure were observed. Embryonic lethality and neural tube defect (NTD) frequency in Folbp1 mice was dose-dependent and differed from the RFC mice; however, no genotype-related differences were observed. The RFC heterozygotes tended to have higher plasma levels of S-adenosylhomocysteine (SAH) than did the wild-type controls, although this effect was not robust. It is concluded that genetic modifications at the Folbp1 and RFC loci confers no particular sensitivity to arsenic toxicity compared to wild-type controls, thus disproving the working hypothesis that decreased methylating capacity of the genetically modified mice would put them at increased risk for arsenic-induced reproductive toxicity.",
Arsenic,628080,"Comparative study on the high prevalence of bladder cancer in the blackfoot disease endemic area in Taiwan Abstract: A stepwise screening program was designed for the epidemiological survey of bladder cancer in the endemic area of blackfoot disease (BFO). Four groups (Group A, 246 BFO patients; Group B, 444 residents of the BFO-endemic area; Group C, 286 residents of the region neighboring the endemic area; Group 0,731 residents of the non-endemic area) totalling 1707 residents were screened by a detailed questionnaire and urinalysis. Three hundred and four cases were screened out and then received a urinary cytology examination. Final results could be compared in the following categories: a positive cytological examination, prevalence of diagnosed bladder cancer and the prevalence of bladder cancer found in the families of sampled residents. In the results of a 4-year investigation, the high prevalence of bladder cancer in the BFO endemic area was noted when compared with that of the control groups. However, some sporadic cases of bladder cancer were noted in the region neighboring the endemic area. Based on the results that all the residents in the BFO endemic area (Groups A and B) were equally affected by a high prevalence of bladder cancer, a common environmental factor or some common factors could exist. It was also shown in our comparative study that the non-endemic areas (Group 0, control group) which also have a high arsenic content in the well water of Taiwan, could not be supported to have a likewise high prevalence of bladder cancer.",
Arsenic,1015767,"Hydrochemical characterization of arsenic contaminated alluvial aquifers in Eastern Croatia using multivariate statistical techniques and arsenic risk assessment Abstract: Multivariate statistical analyses, cluster, factor and discriminant analyses, were used to estimate spatial variations in groundwater chemistry in Eastern Croatia and to identify the main geochemical processes responsible for high arsenic (As) concentrations in the groundwater analyzed. Cluster analysis revealed five different groups of sampling sites linked with groundwater evolution, hydrochemical characteristics and different As content in the groundwater. Two-model factor analysis explained around 50% of total variance of the data sets and enabled identification of the different geochemical processes responsible for higher As concentrations, i.e. decoupled Fe and As reduction and desorption. Using discriminant analysis, a three-parameter discriminant function was derived: electrical conductivity, nitrate and bromide, which yielded highly accurate classification of the samples according to the concentration of As as As-safe (&lt;10?g/L) and As contaminated (&gt;10?g/L). A health risk assessment model was applied to calculate cumulative exposure to As as well as toxic and carcinogenic risks resulting from drinking raw groundwater contaminated by As in Eastern Croatia. Although the results obtained indicate that adverse health effects could be observed among the residents of the villages in which raw groundwater with higher As concentrations has been used, there are no reported cases of arsenicosis.",
Arsenic,1579344,"Investigation of the biotransformation of melarsoprol by electrochemistry coupled to complementary LC/ESI-MS and LC/ICP-MS analysis Abstract: Melarsoprol is the only currently available drug for treatment of the late stage of African trypanosomiasis (sleeping sickness). Unfortunately, the arsenic-containing drug causes serious side effects, for which the mechanisms have not been elucidated so far. This investigation describes the study of the melarsoprol biotransformation processes by electrochemical (EC) techniques. Based on EC, potential oxidation reactions of melarsoprol are examined. Moreover, the reactivity of melarsoprol, its metabolite melarsen oxide, and their oxidation products toward the tripeptide glutathione and the proteins hemoglobin and human serum albumin is evaluated. The combination of different analytical techniques allows the identification as well as the quantification of the biotransformation products. The hyphenation of liquid chromatography (LC) and electrospray ionization mass spectrometry (ESI-MS) is applied for identification and structure elucidation, which implies the determination of exact masses and fragmentation patterns. For the selective detection of arsenic containing metabolites, LC coupled to inductively coupled plasma mass spectrometry is utilized. Based on the obtained data, the oxidative biotransformation of melarsoprol can be predicted, revealing novel species which have been suspected, but not been identified up to now. The results of the protein studies prove that melarsen oxide, the active derivative of melarsoprol, strongly binds to human hemoglobin and forms different adducts via the free cysteinyl groups of the hemoglobin ?- and ?-chain.",
Arsenic,1022118,"Removal of arsenate from groundwater by electrocoagulation method Abstract: PURPOSE: Arsenic, a toxic metalloid in drinking water, has become a major threat for human beings and other organisms. In the present work, attempts have been made to remove arsenate from the synthetic as well as natural water of Ballia district, India by electrocoagulation method. Efforts have also been made to optimize the various parameters such as initial arsenate concentration, pH, applied voltage, processing time, and working temperature. METHOD: Electrocoagulation is a fast, inexpensive, selective, accurate, reproducible, and eco-friendly method for arsenate removal from groundwater. The present paper describes an electrocoagulation method for arsenate removal from groundwater using iron and zinc as anode and cathode, respectively. RESULTS: The maximum removal of arsenate was 98.8% at 2.0 mg L(-1), 7.0, 3.0 V, 10.0 min, and 30°C as arsenate concentration, pH, applied voltage, processing time, and working temperature, respectively. Relative standard deviation, coefficient of determination (r (2)), and confidence limits were varied from 1.50% to 1.59%, 0.9996% to 0.9998%, and 96.0% to 99.0%, respectively. The treated water was clear, colorless, and odorless without any secondary contamination. The developed and validated method was applied for arsenate removal of two samples of groundwater of Ballia district, U.P., India, having 0.563 to 0.805 mg L(-1), arsenate concentrations. CONCLUSIONS: The reported method is capable for the removal of arsenate completely (100% removal) from groundwater of Ballia district. There was no change in the groundwater quality after the removal of arsenate. The treated water was safe for drinking, bathing, and recreation purposes. Therefore, this method may be the choice of arsenate removal from natural groundwater.",
Arsenic,1358885,"Metabolism of arsenic in humans acutely intoxicated by arsenous oxide: Its significance for the duration of BAL (2,3-dimercapto-1-propanol) therapy Abstract: HEEP COPYRIGHT: BIOL ABS. The urinary excretion of inorganic As and of its less toxic metabolites (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)) was followed-up in 5 cases of acute oral intoxication by As2O3. In addition to supportive therapy all patients were given BAL (2,3-dimercapto-1-propanol). The proportion of the 3 species of urinary As changed markedly with time. During the first 2-4 days after intoxication, As was excreted mainly as its unmetabolized inorganic form but this was rapidly followed by a progressive increase of the proportion excreted as MMA and DMA. The time at which the majority of As was excreted as its organic metabolites depended on the severity of the intoxication but in all the cases, 95% of the excreted As was in the organic form after 9 days DMA being preponderant. Speciation of arsenicals in urine might be useful to determine the duration of BAL treatment.",
Arsenic,2064212,"Selective removal of arsenic and monovalent ions from brackish water reverse osmosis concentrate Abstract: Concentrate disposal and management is a considerable challenge for the implementation of desalination technologies, especially for inland applications where concentrate disposal options are limited. This study has focused on selective removal of arsenic and monovalent ions from brackish groundwater reverse osmosis (RO) concentrate for beneficial use and safe environmental disposal using in situ and pre-formed hydrous ferric oxides/hydroxides adsorption, and electrodialysis (ED) with monovalent permselective membranes. Coagulation with ferric salts is highly efficient at removing arsenic from RO concentrate to meet a drinking water standard of 10?g/L. The chemical demand for ferric chloride however is much lower than ferric sulfate as coagulant. An alternative method using ferric sludge from surface water treatment plant is demonstrated as an efficient adsorbent to remove arsenic from RO concentrate, providing a promising low cost, &quot;waste treat waste&quot; approach. The monovalent permselective anion exchange membranes exhibit high selectivity in removing monovalent anions over di- and multi-valent anions. The transport of sulfate and phosphate through the anion exchange membranes was negligible over a broad range of electrical current density. However, the transport of divalent cations such as calcium and magnesium increases through monovalent permselective cation exchange membranes with increasing current density. Higher overall salt concentration reduction is achieved around limiting current density while higher normalized salt removal rate in terms of mass of salt per membrane area and applied energy is attained at lower current density because the energy unitization efficiency decreases at higher current density.",
Arsenic,1015895,"Functional RNA Interference (RNAi) Screen Identifies System A Neutral Amino Acid Transporter 2 (SNAT2) as a Mediator of Arsenic-induced Endoplasmic Reticulum Stress Abstract: Exposure to the toxic metalloid arsenic is associated with diabetes and cancer and causes proteotoxicity and endoplasmic reticulum (ER) stress at the cellular level. Adaptive responses to ER stress are implicated in cancer and diabetes; thus, understanding mechanisms of arsenic-induced ER stress may offer insights into pathogenesis. Here, we identify genes required for arsenite-induced ER stress response in a genome-wide RNAi screen. Using an shRNA library targeting ?20,000 human genes, together with an ER stress cell model, we performed flow cytometry-based cell sorting to isolate cells with defective response to arsenite. Our screen discovered several genes modulating arsenite-induced ER stress, including sodium-dependent neutral amino acid transporter, SNAT2. SNAT2 expression and activity are up-regulated by arsenite, in a manner dependent on activating transcription factor 4 (ATF4), an important mediator of the integrated stress response. Inhibition of SNAT2 expression or activity or deprivation of its primary substrate, glutamine, specifically suppressed ER stress induced by arsenite but not tunicamycin. Induction of SNAT2 is coincident with the activation of the nutrient-sensing mammalian target of rapamycin (mTOR) pathway, which is at least partially required for arsenite-induced ER stress. Importantly, inhibition of the SNAT2 or the System L transporter, LAT1, suppressed mTOR activation by arsenite, supporting a role for these transporters in modulating amino acid signaling. These findings reveal SNAT2 as an important and specific mediator of arsenic-induced ER stress, and suggest a role for aberrant mTOR activation in arsenic-related human diseases. Furthermore, this study demonstrates the utility of RNAi screens in elucidating cellular mechanisms of environmental toxins.",
Arsenic,2343427,"Biodynamic modelling of the bioaccumulation of trace metals (Ag, As and Zn) by an infaunal estuarine invertebrate, the clam Scrobicularia plana Abstract: Biodynamic modelling was used to investigate the uptake and accumulation of three trace metals (Ag, As, Zn) by the deposit feeding estuarine bivalve mollusc Scrobicularia plana. Radioactive labelling techniques were used to quantify the rates of trace metal uptake (and subsequent elimination) from water and sediment diet. The uptake rate constant from solution (±SE) was greatest for Ag (3.954±0.375lg(-1)d(-1)) followed by As (0.807±0.129lg(-1)d(-1)) and Zn (0.103±0.016lg(-1)d(-1)). Assimilation efficiencies from ingested sediment were 40.2±1.3% (Ag), 31.7±1.0% (Zn) and 25.3±0.9% (As). Efflux rate constants after exposure to metals in the solution or sediment fell in the range of 0.014-0.060d(-1). By incorporating these physiological parameters into biodynamic models, our results showed that dissolved metal is the predominant source of accumulated Ag, As and Zn in S. plana, accounting for 66-99%, 50-97% and 52-98% of total accumulation of Ag, As and Zn, respectively, under different field exposure conditions. In general, model-predicted steady state concentrations of Ag, As and Zn matched well with those observed in clams collected in SW England estuaries. Our findings highlight the potential of biodynamic modelling to predict Ag, As and Zn accumulation in S. plana, taking into account specific dissolved and sediment concentrations of the metals at a particular field site, together with local water and sediment geochemistries.",
Arsenic,1020656,"Metal content in femoral head spongious bone of people living in regions of different degrees of environmental pollution in Southern and Middle Poland Abstract: The content of calcium, phosphorus, magnesium, potassium, iron, zinc, copper, lead, cadmium, arsenic, and silver was evaluated in femoral head spongious bone of inhabitants of southern (Silesia, n = 13; Cracow, n = 13) and middle Poland (Lodz, n = 12). A total of 38 persons (29 females and 9 males) were included in the study. The average age in the Silesian group was 68 +/- 9.9 years old, in the group from Cracow 69.2 +/- 9.6 years old, and 68.3 +/- 7.3 years old for the inhabitants of Lodz. The AAS method was used to determine the femoral heads metal content after microwave mineralization. A similar content of calcium (av 18.4% dry weight), phosphorus (av 6.8%), magnesium (av 1883.5 microg/g), potassium (av 598.1 microg/g), iron (av 59.5 microg/g), zinc (av 90.1 microg/g), copper (av 90.1 microg/g), arsenic (av 0.3 microg/g), and silver (av 0.03 microg/g) was found in every group. Specimens from different regions differed in lead and cadmium content, illustrating the differences in environmental pollution exposure.",
Arsenic,1352590,Antioxidant and anti-inflammatory effect of conjugated linolenic acid isomers against streptozotocin-induced diabetes Abstract: ,
Arsenic,2278563,"A complexity measure based method for studying the dependance of 222Rn concentration time series on indoor air temperature and humidity Abstract: We have suggested a complexity measure based method for studying the dependence of measured (222)Rn concentration time series on indoor air temperature and humidity. This method is based on the Kolmogorov complexity (KL). We have introduced (i) the sequence of the KL, (ii) the Kolmogorov complexity highest value in the sequence (KLM) and (iii) the KL of the product of time series. The noticed loss of the KLM complexity of (222)Rn concentration time series can be attributed to the indoor air humidity that keeps the radon daughters in air.",
Arsenic,1749271,"Toxicological status of children with autism vs. neurotypical children and the association with autism severity Abstract: This study investigates both the level of toxic metals in children with autism and the possible association of those toxic metals with autism severity. This study involved 55 children with autism ages 5-16 years compared to 44 controls with similar age and gender. The study included measurements of toxic metals in whole blood, red blood cells (RBC), and urine. The autism group had higher levels of lead in RBC (+41 %, p = 0.002) and higher urinary levels of lead (+74 %, p = 0.02), thallium (+77 %, p = 0.0001), tin (+115 %, p = 0.01), and tungsten (+44 %, p = 0.00005). However, the autism group had slightly lower levels of cadmium in whole blood (-19 %, p = 0.003). A stepwise, multiple linear regression analysis found a strong association of levels of toxic metals with variation in the degree of severity of autism for all the severity scales (adjusted R(2) of 0.38-0.47, p &lt; 0.0003). Cadmium (whole blood) and mercury (whole blood and RBC) were the most consistently significant variables. Overall, children with autism have higher average levels of several toxic metals, and levels of several toxic metals are strongly associated with variations in the severity of autism for all three of the autism severity scales investigated.",
Arsenic,2278353,"Arsenic contamination: Africa the missing gap Abstract: Arsenic is becoming a major challenge around the world due to its effect on human health. The World Health Organization set the standard for arsenic as 10 ?g/L but most country do not adhere to this but rather still work with old standard of 50 ?g/L. A lot of research has been carried out in different part of the world to determine the level of contamination. Europe has been able to reduce the effect of arsenic to the extent that it is almost non existence. Other continents are also trying to reduce the effect of arsenic and this can be seen from the number of research that has been reported. However, Africa is behind in this regard and not much data can be obtained on arsenic pollution or contamination. There is therefore a need for a thorough monitoring of arsenic in Africa so as to have a true picture of the level of arsenic contamination in Africa.",
Arsenic,8473,"Mortality experience in relation to a measured arsenic trioxide exposure Abstract: This report examines the mortality experience of 527 men who retired from a copper smelter where they were exposed to airborne arsenic trioxide. Urinary arsenic values of all plant employees were determined in 1973, and the relative arsenic exposure in the various departments of the plant were determined. The relationship of airborne arsenic concentrations to urinary arsenic values was studied in a separate experiment, and the feasibility of using urinary arsenic values as a measure of arsenic exposure was established. The mortality experience of the cohort under study showed them to have a mortality 12.2% higher than was found for males of the same area at the same ages and in the same time period. The excess mortality was due chiefly to respiratory cancer. When the deaths were classified by total lifetime arsenic exposure, the respiratory cancer mortality was linearly related to the amount of exposure. The 1973 figures for arsenic exposure underestimated the exposure of the cohort group by a factor of possibly 10. Evidence was obtained which suggests that after removal from arsenic exposure, the risk of lung cancer declines. Certain of the data which are presented suggests there may be a threshold value for airborne arsenic trioxide exposure below which no adverse effects may be expected.",
Arsenic,1353574,Bioremediation of industrial effluents containing heavy metals using brewing cells of Saccharomyces cerevisiae as a green technology: a review Abstract: ,
Arsenic,1346369,SPECTROPHOTOMETRIC DETERMINATION OF ANTIMONY WITH PHENYLFLUORONE AND ITS APPLICATION IN ANALYSIS OF LEAD AND ARSENIC Abstract: ,
Arsenic,1018347,"Arsenic content in hair of people exposed to natural arsenic polluted groundwater at Zimapán, México Abstract: ",
Arsenic,509458,"Study of arsenic content in mine groundwater commonly used for human consumption in Utah Abstract: Of the various sources of arsenic released in to the environment, the presence of arsenic in water probably poses the greatest threat to human health. Arsenic is released in to the environment through water by dissolution of minerals and ores. Natural release is slow, but in some areas the concentration of arsenic in groundwater (commonly referred to as Acid Mine Drainage (or AMD)) is accelerated by mining activity. In fact the presence of arsenic may last a long time even after the mining activity has ceased. Hence it is imperative to study the quality of water (especially for those areas in the vicinity of mines) used for different purposes to identify an appropriate remediation technique for effective pollution control. In this paper, contents of arsenic and other metals in the water were quantified from three different sources: (1) groundwater from the mining tunnel (judge tunnel), (2) drinking water, and (3) water used in the hydrant-flushed distribution system (Park City) in Utah (USA). The results showed the content of arsenic from the mining tunnel, after chlorination, and in tap water were below 10 mu g l(-1). However, significant amounts of arsenic, lead, zinc, iron, manganese and antimony have been found in water samples taken from the distribution systems. In the consideration of the further use of mine groundwater for drinking purposes and the distribution system, Park City should regularly be maintained by a flushing program in the distribution system.",
Arsenic,598024,"Urothelial cells malignantly transformed by exposure to cadmium (Cd(+2)) and arsenite (As(+3)) have increased resistance to Cd(+2) and As(+3)-induced cell death Abstract: This laboratory has shown that both Cd(+2) and As(+3) can malignantly transform human urothelial cells. The present study examined metal resistance and the mechanism of cell death when the parental and malignantly transformed UROtsa cells were exposed to Cd(+2) and As(+3). It was shown that the malignantly transformed UROtsa cells were more resistant to the toxic effects of both metals. The assessment of the mode of cell death demonstrated that the parental UROtsa cells died by both apoptosis and necrosis when exposed to either metal. It was shown that apoptosis was the more prominent mechanism of cell death, accounting for over 50% of cell death. Apoptotic cell death was determined by the observation of fragmented nuclei using 4',6-diamidino-2-phenylindole staining, the formation of a DNA ladder, and the detection of cleaved caspase-3 and caspase-9 products in the cell lysates. Necrotic cell death was determined by measuring the release of lactate dehydrogenase into the growth medium. It was determined that the extent of apoptosis of the malignantly transformed UROtsa cells was decreased and that the extent of necrosis was increased compared to the parental UROtsa cells. These observations are consistent with in vivo studies which suggest that As(+3) can act as a tumor promoter during the regeneration of the bladder urothelium. The present in vitro studies suggest that As(+3)-induced cytotoxicity could set the stage for tissue repair due to its own inherent toxicity to normal urothelium, and then subsequently act as a tumor promoter during the regeneration process through the stimulation of the regrowth of cells that have gained increased resistance to As(+3).",
Arsenic,628704,"Cytotoxicity of combinations of arsenicals on rat urinary bladder urothelial cells in vitro Abstract: Based on epidemiological data, chronic exposure to high levels of inorganic arsenic in the drinking water is carcinogenic to the urinary bladder of humans. The highly reactive trivalent organic arsenicals dimethylarsinous acid (DMA(III)) and monomethylarsonous acid (MMA(III)) are formed during the metabolism of inorganic arsenic in vivo in addition to the corresponding mono-, di- and trimethylated pentavalent arsenicals. The objective of this study was to determine if combining arsenicals was additive or synergistic toward inducing cytotoxicity in a rat urothelial cell line. The MYP3 cell line, an immortalized but not transformed rat urinary bladder epithelial cell line, was seeded into appropriate culture wells. Treatment with the arsenicals was begun 24 h after seeding and continued for 3 days. Combinations of arsenicals used were DMA(III) with arsenite, dimethylarsinic acid (DMA(V)) or trimethylarsine oxide (TMAO). Combinations of concentrations used were the LC50, one-quarter or one-half the LC50 of one arsenical with one-half or one-quarter the LC50 of the other arsenical. To determine if MYP3 cells metabolize arsenicals, cells were treated with arsenate, arsenite and MMA(V) as described above and the medium was analyzed by HPLC-ICPMS to determine species and quantity of arsenicals present. When cells were treated with one-quarter or one-half the LC50 concentration of both arsenicals, the cytotoxicity was approximately the same as when cells were treated with half the LC50 concentration or the LC50 concentration, respectively, of either arsenical. Treatment with one-quarter the LC50 concentration of one arsenical plus the LC50 concentration of a second arsenical had similar cytotoxicity as treatment with the LC50 concentration of either of the arsenicals. Quantitation and speciation of arsenicals in the cell culture medium showed that MYP3 cells have some reductase activity but the cells do not methylate arsenicals. The effect on the cytotoxicity of arsenicals in combination was additive rather than synergistic toward a rat urothelial cell line.",
Arsenic,1519057,"A prospective study of tobacco smoking and mortality in Bangladesh Abstract: <strong>BACKGROUND: </strong>Limited data are available on smoking-related mortality in low-income countries, where both chronic disease burden and prevalence of smoking are increasing.<br /><br /><strong>METHODS: </strong>Using data on 20, 033 individuals in the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh, we prospectively evaluated the association between tobacco smoking and all-cause, cancer, and cardiovascular disease mortality during ?7.6 years of follow-up. Cox proportional hazards models were used to estimate hazard ratios (HRs) and their 95% confidence intervals (CIs) for deaths from all-cause, cancer, CVD, ischemic heart disease (IHD), and stroke, in relation to status, duration, and intensity of cigarette/bidi and hookah smoking.<br /><br /><strong>RESULTS: </strong>Among men, cigarette/bidi smoking was positively associated with all-cause (HR 1.40, 95% CI 1.06 1.86) and cancer mortality (HR 2.91, 1.24 6.80), and there was a dose-response relationship between increasing intensity of cigarette/bidi consumption and increasing mortality. An elevated risk of death from ischemic heart disease (HR 1.87, 1.08 3.24) was associated with current cigarette/bidi smoking. Among women, the corresponding HRs were 1.65 (95% CI 1.16 2.36) for all-cause mortality and 2.69 (95% CI 1.20 6.01) for ischemic heart disease mortality. Similar associations were observed for hookah smoking. There was a trend towards reduced risk for the mortality outcomes with older age at onset of cigarette/bidi smoking and increasing years since quitting cigarette/bibi smoking among men. We estimated that cigarette/bidi smoking accounted for about 25.0% of deaths in men and 7.6% in women.<br /><br /><strong>CONCLUSIONS: </strong>Tobacco smoking was responsible for substantial proportion of premature deaths in the Bangladeshi population, especially among men. Stringent measures of tobacco control and cessation are needed to reduce tobacco-related deaths in Bangladesh.",
Arsenic,734855,"Urinary 8-hydroxydeoxyguanosine and urothelial carcinoma risk in low arsenic exposure area Abstract: Arsenic is a well-documented human carcinogen and is known to cause oxidative stress in cultured cells and animals. A hospital-based case-control study was conducted to evaluate the relationship among the levels of urinary 8-hydroxydeoxyguanosine (8-OHdG), the arsenic profile, and urothelial carcinoma (UC). Urinary 8-OHdG was measured by using high-sensitivity enzyme-linked immunosorbent assay (ELISA) kits. The urinary species of inorganic arsenic and their metabolites were analyzed by high-performance liquid chromatography (HPLC) and hydride generator-atomic absorption spectrometry (HG-AAS). This study showed that the mean urinary concentration of total arsenics was significantly higher, at 37.67±2.98 ?g/g creatinine, for UC patients than for healthy controls of 21.10±0.79 ?g/g creatinine (p<0.01). Urinary 8-OHdG levels correlated with urinary total arsenic concentrations (r=0.19, p<0.01). There were significantly higher 8-OHdG levels, of 7.48±0.97 ng/mg creatinine in UC patients, compared to healthy controls of 5.95±0.21 ng/mg creatinine. Furthermore, female UC patients had higher 8-OHdG levels of 9.22±0.75 than those of males at 5.76±0.25 ng/mg creatinine (p<0.01). Multiple linear regression analyses revealed that high urinary 8-OHdG levels were associated with increased total arsenic concentrations, inorganic arsenite, monomethylarsonic acid (MMA), and dimethylarsenate (DMA) as well as the primary methylation index (PMI) even after adjusting for age, gender, and UC status. The results suggest that oxidative DNA damage was associated with arsenic exposure, even at low urinary level of arsenic.",
Arsenic,2345795,"Lichens as sentinels for air pollution at remote alpine areas (Italy) Abstract: The present study was undertaken with the aim of using epiphytic lichens as sentinels for air pollution at two remote alpine sites (1,400 and 1,800 m above sea level (asl)) of NW Italy. The results indicated that the site at 1,800 m prompted for early warning indications of biological changes. Although levels of the many elements assayed in samples of the lichen Pseudevernia furfuracea (L.) Zopf, ranging from minor elements (e.g., Al) to ultra-trace (e.g., Pt), were at normal levels, indications of a slowly worsening environment were given by the lichen biodiversity and by damage to cell membranes. The analysis of Pb isotopic ratios suggested that the origin of Pb accumulated in lichens is not local, but linked to the long-range transport by air masses. It was concluded that the origin of pollutants is from air mass coming from the Po plain of Italy and from densely populated areas of Switzerland and France.",
Arsenic,1372744,"Modulatory Effect Of The Green Tea Flavonoid Epigallocatechin 3-Gallate On Arsenite- And Hydrogen Peroxide-Stimulated Mitogen-Activated Protein Kinase Phosphorylation And Heme Oxygenase-1 Expression In Human Dermal Fibroblasts Abstract: Reactive oxygen species (ROS) are proposed to contribute to arsenic carcinogenesis and in skin ROS activate mitogen-activated protein kinases (MAPKs) that regulate cell growth. Green tea polyphenols are effective cancer chemopreventive agents and exert their scavenging effects against ROS and also modulate MAPK activity. Because carcinogenesis, ROS, and MAPKs can be modulated by polyphenols, we examined the activation (phosphorylation) of p42/44 and p38 MAPKs in human dermal fibroblasts (HDF) by sodium arsenite (AsIII) alone and in the presence of the small molecular weight green tea polyphenol epigallocatechin 3-gallate (EGCG). Induction of the cellular antioxidant enzyme and stress sensor heme oxygenase- 1 (HO-1) also was examined under these conditions. Western blot analyses indicate that noncytotoxic AsIII (5 ?M) and hydrogen peroxide ([H202] positive ROS control) stimulate p42/44 and p38 phosphorylation and elevate HO-1 protein expression in HDF. Short-term (3 hr) EGCG treatment (40 ?M) inhibited p42/44 phosphorylation independent of AsIII or H202 exposure. In addition, it reduced p42/44 and p38 phosphorylation at 15 and 30 minutes post-H202 treatment. No effect on HO-1 induction stimulated by AsIII or H202 was observed after short-term EGCG treatment. Long-term (24 hr) EGCG treatment (40 ?M) had no inhibitory effect on p42/44 or p38 phosphorylation, or the induction of HO-1 stimulated by either AsIII or H202. These data indicate that EGCG has little to no effect on AsIII-stimulated MAPK activation and HO-1 induction in our experimental system. It is anticipated that data from this study will contribute to a better understanding of arsenic skin carcinogenesis and the mechanisms of polyphenols as cancer chemotherapeutics.",
Arsenic,1349140,"Changes in the regulation of heat shock gene expression in neuronal cell differentiation Abstract: Neuronal differentiation of the NG108-15 neuroblastoma-glioma hybrid cells is accompanied by a marked attenuation in the heat shock induction of the Hsp70-firefly luciferase reporter gene activity. Analysis of the amount and activation of heat shock factor 1, induction of mRNA(hsp), and the synthesis and accumulation of heat shock proteins (HSPs) in the undifferentiated and differentiated cells suggest a transcriptional mechanism for this attenuation. Concomitant with a decreased induction of the 72-kDa Hsp70 protein in the differentiated cells, there is an increased abundance of the constitutive 73-kDa Hsc70, a protein known to function in vesicle trafficking. Assessment of sensitivity of the undifferentiated and differentiated cells against stress-induced cell death reveals a significantly greater vulnerability of the differentiated cells toward the cytotoxic effects of arsenite and glutamate/glycine. This study shows that changes in regulation of the HSP and HSC proteins are components of the neuronal cell differentiation program and that the attenuated induction of HSPs likely contributes to neuronal vulnerability whereas the increased expression of Hsc70 likely has a role in neural-specific functions.",
Arsenic,1936165,"Kinetics and thermodynamics of sorption for As(V) on the porous biomorph-genetic composite of ?-Fe2O3/Fe3O4/C with eucalyptus wood hierarchical microstructure Abstract: A novel porous biomorph-genetic composite of ?-Fe2O3/Fe3O4/C (PBGC-Fe/C) with eucalyptus wood template was prepared, characterized and tested for its sorption capacity of As(V) from aqueous solution. The result indicated that the PBGC-Fe/C material retained the hierarchical porous structure of eucalyptus wood with three different types of pores (widths 70-120, 4.1-6.4 and 0.1-1.3 ?m) originating from vessels, fibres and pits of the wood, respectively. Its surface area was measured to be 59.2 m2/g. With increasing initial As(V) concentration from 5 to 100 mg/L, the amounts of As(V) sorbed on the pulverized PBGC-Fe/C sorbent (<0.149 mm) increased from 0.50 to 4.01 mg/g at 25 °C, from 0.50 to 4.83 mg/g at 35 °C and from 0.50 to 4.19 mg/g at 45 °C, and the corresponding removal rates decreased from 99.97 to 40.10 % at 25 °C, 99.95 to 48.40 % at 35 °C and 99.92 to 42.05 % at 45 °C. At the initial concentrations of 5, 10 and 50 mg/L, the sorption capacities for the unpulverized PBGC-Fe/C sorbent (>3 mm) were determined to be 0.50, 0.99 and 2.49 mg/g, respectively, which exhibited a similar average value to those of fine particles or nanoparticles of iron oxides. The sorption could well be described by the pseudo-second-order kinetic equation. The equilibrium data were found to follow Freundlich as well as Langmuir isotherms.",
Arsenic,1337582,"Evidence of population genetic effects in Peromyscus melanophrys chronically exposed to mine tailings in Morelos, Mexico Abstract: Effects of environmental chemical pollution can be observed at all levels of biological organization. At the population level, genetic structure and diversity may be affected by exposure to metal contamination. This study was conducted in Huautla, Morelos, Mexico in a mining district where the main contaminants are lead and arsenic. Peromyscus melanophrys is a small mammal species that inhabits Huautla mine tailings and has been considered as a sentinel species. Metal bioaccumulation levels were examined by inductively coupled plasma mass spectrometry and genetic analyses were performed using eight microsatellite loci in 100 P. melanophrys individuals from 3 mine tailings and 2 control sites. The effect of metal bioaccumulation levels on genetic parameters (population and individual genetic diversity, genetic structure) was analyzed. We found a tissue concentration gradient for each metal and for the bioaccumulation index. The highest values of genetic differentiation (Fst and Rst) and the lowest number of migrants per generation (Nm) were registered among the exposed populations. Genetic distance analyses showed that the most polluted population was the most genetically distant among the five populations examined. Moreover, a negative and significant relationship was detected between genetic diversity (expected heterozygosity and internal relatedness) and each metal concentration and for the bioaccumulation index in P. melanophrys. This study highlights that metal stress is a major factor affecting the distribution and genetic diversity levels of P. melanophrys populations living inside mine tailings. We suggest the use of genetic population changes at micro-geographical scales as a population level biomarker.",
Arsenic,1252338,"Epidemiological associations between arsenic and cancer in Argentina Abstract: The population of a large central area of Argentina is affected by a syndrome designed as “regional and endemic chronic hydroarsenicism.” A number of types of neoplasms, especially of skin, urinary bladder, and of digestive system, occur with higher frequency in these areas. Drinking water in some of the affected areas contains from 0.1 to 1.2 mg/L of As.",
Arsenic,1070392,"Assessment of Metal Concentrations in Two Cyprinid Fish Species (Leuciscus cephalus and Tinca tinca) Captured from Yeniça?a Lake, Turkey Abstract: This study was performed to investigate certain major and toxic metal concentrations in muscle, gill and liver tissues of two Cyprinid species (Leuciscus cephalus, Tinca tinca). Generally liver and gill tissue exhibited higher metal concentrations than did muscle. The highest metal concentrations found in tench and chub muscle tissues were determined to be Al (59.01-108 mg kg(-1)), Zn (45.23-57.81 mg kg(-1)), Fe (9.23-16.03 mg kg(-1)) and Ba (3.50-2.69 mg kg(-1)) respectively. The level of metal accumulation is evaluated for potential risk to human health based on international standards. Zinc, lead and arsenic values of muscle tissues of the fishes were found to be above the allowed limits for human consumption.",
Arsenic,2064252,"Sorption and Redox Reactions of As(III) and As(V) within Secondary Mineral Coatings on Aquifer Sediment Grains Abstract: Important reactive phenomena that affect the transport and fate of many elements occur at the mineral-water interface (MWI), including sorption and redox reactions. Fundamental knowledge of these phenomena are often based on observations of ideal mineral-water systems, for example, studies of molecular scale reactions on single crystal faces or the surfaces of pure mineral powders. Much less is understood about MWI in natural environments, which typically have nanometer to micrometer scale secondary mineral coatings on the surfaces of primary mineral grains. We examined sediment grain coatings from a well-characterized field site to determine the causes of rate limitations for arsenic (As) sorption and redox processes within the coatings. Sediments were obtained from the USGS field research site on Cape Cod, MA, and exposed to synthetic contaminated groundwater solutions. Uptake of As(III) and As(V) into the coatings was studied with a combination of electron microscopy and synchrotron techniques to assess concentration gradients and reactive processes, including electron transfer reactions. Transmission electron microscopy (TEM) and X-ray microprobe (XMP) analyses indicated that As was primarily associated with micrometer- to submicrometer aggregates of Mn-bearing nanoparticulate goethite. As(III) oxidation by this phase was observed but limited by the extent of exposed surface area of the goethite grains to the exterior of the mineral coatings. Secondary mineral coatings are potentially both sinks and sources of contaminants depending on the history of a contaminated site, and may need to be included explicitly in reactive transport models.",
Arsenic,56724,"Effects of coal combustion products and metal compounds on sister chromatid exchange (SCE) in a macrophagelike cell line Abstract: Investigations of genotoxic effects of particles have almost exclusively been performed by organic extraction, while direct investigations in cells capable of engulfing particles have only been performed in few cases. Thus, in most studies, the eventual effects of particle-associated metal compounds have remained undiscovered. The present study attempted direct measurement of genotoxic effects of particulate coal combustion products by using the P388D1 macrophage cell line. The capability of these cells for phagocytosis was demonstrated with insoluble particles. The sister chromatid exchange (SCE) test was used for measuring genotoxic effects of test compounds. Dimethylnitrosamine and benzo(a)pyrene did not increase SCE, indicating that the P388D1 cell line has lost the capacity for metabolism of latent organic carcinogens, reducing the value of these cells for evaluating genotoxic effects of complex particles. Indirect evidence has been obtained that the cell line may be infected with a virus. Thus, interactions between virus and test compound may lead to erroneous results. This should be kept in mind during evaluation of the results.The effects of metals with reported carcinogenic or mutagenic effects on SCE were compared in P388D1 cells and human lymphocytes: NaAsO2, CdCl2, K2Cr2O7, CoCl2, CH3HgCl and MnSO4 increased SCE in both cell systems. Pb(CH3COO)2, BeSO4 and NiSO4 had a weak effect on SCE in P388D1. Pb(CH3COO)2 and NiSO4, but not BeSO4, increased SCE in human lymphocytes. Cr(CH3COO)3 increased SCE in human lymphocytes at high concentration, but was a strong inducer of increased SCE in P388D1 cells, which take up Cr(III) by phagocytosis. This suggests that the Cr(III) ion is an ultimate carcinogenic form of chromium. Generally P388D1 cells and human lymphocytes respond to in vitro exposure to metals in agreement with reported mutagenic/carcinogenic effects of the metals.Of four precipitated coal fly ash samples tested, only one sample (from an electrostatic precipitator downstream of a cyclone at an electricity generating plant burning pulverized coal) had a clear increasing effect on SCE in P388D1. Extraction of this sample with medium with 10% serum yielded an extract capable of increasing SCE. The extracted particles still increased SCE, but less than unextracted particles.Emission samples taken with impactor sampler after a dilution probe using controlled cooling of the flue gas were obtained from an oil-fired (one sample) and a coal-fired (one sample < 3 ?m and one sample < 3 ?m) steam boiler. The only sample increasing SCE was the sample < 3 ?m from the coal-fired boiler. Extract from this sample also increased SCE.The results demonstrated that the use of phagocytizing cells for assessment of genotoxic effects of particles offers a useful system, since the particles can be investigated directly. Furthermore, particles, extracted particles and extract can be investigated in the same system.",
Arsenic,1508607,"Involvement of mtDNA damage elicited by oxidative stress in the arsenical skin cancers Abstract: Arsenic causes several human cancers. Arsenic-induced Bowen's disease (As-BD), the most common arsenical cancers, is characterized by increased proliferation, dysplasia, and individual cell apoptosis, all of which involve mitochondria. We reported arsenic causes aberrant keratinocyte proliferation through mtTFA-mediated mitochondrial biogenesis in As-BD. Increasing mitochondrial biogenesis render cells undergo oxidative stresses. However, how arsenic induces oxidative stress and causes mitochondrial DNA (mtDNA) damage in arsenical cancers remains largely unknown. Using tissues from As-BD patients and arsenic-treated keratinocytes, we determined the oxidative stress, antioxidant enzymes, DNA repair enzymes, and 8-OHdG level in mtDNA by immunofluorescence, real-time PCR, and Western blot. The results showed that oxidative stress was enhanced in both As-BD and arsenic-treated keratinocytes. Antioxidant enzymes including Mn-SOD and Cu/Zn-SOD and DNA repair enzymes were upregulated concomitantly in tissues and cells. In arsenic-treated keratinocytes, increased mitochondrial oxidative stress and the 8-OHdG level in mtDNA was attenuated by pretreatment with ascorbic acid, a potent antioxidant. Further, we found several somatic mutations in the ND4, ND5 and ND6 genes of mtDNA in lesional but not in perilesional skin from As-BD patients. Taken together, the results suggest oxidative damage and mutations to mtDNA might be involved in the arsenical skin cancers in the context of mitochondrial biogenesis.Journal of Investigative Dermatology accepted article preview online, 31 January 2013;. doi:10.1038/jid.2013.55.",
Arsenic,2347797,"Identification of wetland water sources for environmental flow assessment: A case study of the Miguel Ibanez wetlands (Segovia, Spain) Abstract: This work aims to identify wetland water sources for environmental flow assessment of three wetlands located in the area of Miguel Ibanez (Segovia, Spain), known as Fuente Santa, Balsa de la Ermita and San Pedro ponds. These are remnants of wetland systems that were larger in the past. The methodology used involved four seasonal field campaigns conducted in 2012 at eight main and three additional surface water or groundwater sampling points. The interpretation of the physico-chemical and isotopic data obtained, and daily monitoring of changes in the water level of the Fuente Santa pond over 5 months provided an initial understanding of the environmental flows needed to sustain these wetlands in appropriate conditions. The arsenic values provided an additional auxiliary tool, although a single dominant cause of its presence in these three ponds could not be identified. The results show that the interactions between the wetlands and groundwater are hydrogeologically different despite their proximity to one another. These findings will enable the improved management and conservation of these wetlands.",
Arsenic,2337128,"A double-blind, randomize, placebo-control trial to evaluate the effect of Nigella sativa on palmer arsenical keratosis patients Abstract: This study was done to examine the role of Nigella sativa in 28 patients of palmer arsenical keratosis. Patients were randomized into two groups: Group A (n-15) receive capsules of placebo and vitamin E (200 mg) whereas Group B (n= 13) receive capsules of N. sativa oil (500 mg) and vitamin E (200 mg) orally for 8 weeks. The mean (+/- SD) clinical scoring of palmer arsenical keratosis in Group A before and after treatment was 99.3 +/- 21.5 and 62.3 +/- 14.3 respectively (37% reduction). On the other hand, in N. sativa oil treated group, the mean clinical score was 119.1 +/- 20.3 before treatment which was reduced to 39.2 +/- 8.4 (p<0.0001) after treatment (67% reduction). There were 65% reduction of total arsenic in nail of Group A and 30% in Group B. In conclusion, oral administration of N. sativa oil improves the symptom of palmer arsenical keratosis as a result of reduction of body arsenic load.",
Arsenic,749370,"Low levels of occupational exposure to arsenic and antimony: Effects on lysosomal glycohydrolase levels in plasma of exposed workers and in lymphocyte cultures Abstract: BACKGROUND: Heavy metals have been shown to alter the mechanism and release of lysosomal enzymes. In the present study, the activities of lysosomal glycohydrolases were determined in order to evaluate the asymptomatic toxic effects of low levels of exposure to arsenic (As) and antimony (Sb) in art glass workers. METHODS: N-acetyl-beta-D-glucosaminidase (NAG), beta-D-glucuronidase (GCR), alpha- and beta-D-galactosidase, alpha-D-glucosidase, and alpha-D-mannosidase were determined by a fluorimetric assay in the plasma of 26 art glass workers. Lymphocytes cultured in the presence of different species of As and Sb served as an in vitro model for the study of the protective action of selenium and zinc. RESULTS: No significant difference in the plasma levels of the various enzymes was detected in art glass workers or control subjects. The in vitro experiments demonstrated that secretion of lysosomal glycohydrolases was increased by Sb (225%) and decreased by As (57%) at the same concentration of elements (200 microg/L). The addition of bivalent selenium to the culture neutralized the effects of both metals, while zinc chloride did not show any protective effect. CONCLUSIONS: As for the plasma glycohydrolases, no praecox signs of toxicity related to a low concentration of As and Sb was evident in art glass workers. This may be due to the antagonistic effects demonstrated by these two metals in vitro. Their different mechanism of action on release of glycohydrolases is being discussed.",
Arsenic,1004825,"Association of melamine exposure with urinary stone and oxidative DNA damage in infants Abstract: There is evidence in experimental animals for the urolithiasis and carcinogenicity of melamine, but no evidence for melamine in humans. To evaluate any association between melamine-contaminated powdered formula (MCPF) feeding and urolithiasis, and further the MCPF feeding and oxidative damage to DNA in infants. A cross-sectional study was carried out to assess urolithiasis and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) in four groups of infants according to the type of feeding: (1) Infants receiving over 90% of their intake as MCPF. (2) Infants receiving 50-90% of their intake as MCPF. (3) Infants receiving less than 50% of their intake as MCPF. (4) Infants receiving over 90% of their intake as imported milk powdered formula free of melamine contamination. Groups 1 to 3 are the observation groups, and Group 4 is the reference group. There is a significant correlation between urolithiasis and percentage of MCPF intake. The mean urinary 8-OHdG concentrations for Groups 1, 2, 3, and 4 were: 2.03 +/- 0.52, 1.67 +/- 0.28, 1.90 +/- 0.39, and 1.85 +/- 0.47 micromoles per mole of creatinine, respectively. There were no significant differences in the mean urinary 8-OHdG concentrations among the observation and control groups. There were also no correlation between mean urinary 8-OHdG excretions and percentage of MCPF intake. Our data suggested that melamine exposure were associated with urolithiasis, but it might not cause any increase in oxidative damage of DNA in infants.",
Arsenic,1251502,"Identification of a second region upstream of the mouse heme oxygenase-1 gene that functions as a basal level and inducer-dependent transcription enhancer Abstract: A 161-base pair fragment (AB1) approximately 10 kilobase pairs upstream of the transcription start site of the mouse heme oxygenase-1 gene functions as a basal level and inducer-dependent enhancer. AB1/chloramphenicol acetyltransferase fusion genes stably transfected into mouse hepatoma (Hepa) cells or L929 fibroblasts were activated 7-8- or 17-22-fold, respectively, after treatment of the cells with either CdCl2 or heme. The AB1 fragment is composed largely of three tandem repeats containing two conserved core elements, A and B. Part of core element A (TCCGGAGCTGTG) resembles the consensus-binding site for transcription factor AP-4, whereas core element B (GCTGAGTCANGG) includes the consensus-binding site (TGAGTCA) for the AP-1 family of transcription factors. Nuclear proteins from Hepa cells did not bind to any of the core A elements, but bound to all three copies of the core B element. AB1 derivatives with one or two mutant AP-1-binding elements exhibited reduced but measurable inducer-dependent enhancer activity, but mutation of all three AP-1-binding sites abolished activation by CdCl2 and heme and also by mercury chloride, zinc chloride, H2O2, sodium arsenate, and 12-O-tetradecanoylphorbol-13-acetate. Pretreatment of stably transfected L929 cells with protein kinase C inhibitors, but not with tyrosine kinase inhibitors or N-acetylcysteine, abrogated 12-O-tetradecanoylphorbol-13-acetate-dependent activation of the AB1/chloramphenicol acetyltransferase fusion gene. Induction by H2O2 was unaffected by the kinase inhibitors, but completely abolished by N-acetylcysteine. Heme-dependent induction was not significantly affected by any of these chemicals.",
Arsenic,1357442,"Induction of a 70-kDa Protein in Human Lymphocytes Exposed to Inorganic Heavy Metals and Toxic Organic Compounds Abstract: The induction of a 70 kilodalton (kDa) protein (p70) distinct from metallothionein (MT) in human lymphocytes exposed to inorganic heavy metals and toxic organic compounds was examined. Human peripheral blood mononuclear cells were cultured and incubated with several inorganic heavy metals and other toxic pollutants, including cadmium (7440439) (Cd), zinc (7440666) (Zn), copper (7440508), mercury (7439976), manganese (7439965), cobalt (7440484) (Co), lead (7439921), tin (7440315), arsenic (7440382), iron (7439896), malathion (121755), chlorpyrifos (2921882), and acephate (30560191). Proteins were labeled with sulfur-32-methionine and detected using polyacrylamide gel electrophoresis and fluorography. Results showed that in the cells exposed to salts of Cd, Zn, and Co, there was a specific induction of a protein with a molecular ratio (Mr) of 70,000 (p70), and that this induction was dose dependent. At high concentration, the overall level of protein synthesis declined due to the cytotoxic effects, but even at these ranges a protein with an Mr of 90,000 (p90) was seen to be maintained as compared with the other proteins. The other metals and arsenates had no ability to induce p70. Further experiments to ascertain whether the p70 was identical to a heat shock protein (hsp70) known to be induced by Cd showed that they were indistinguishable from each other. The agricultural chemical pollutants tested were also able to induce the synthesis of lymphocyte p70. The authors conclude that p70 may be involved in the basic cellular defense mechanisms related to responses to environmental stimuli.",
Arsenic,656862,"Enhanced transcription factor DNA binding and gene expression induced by arsenite or arsenate in renal slices Abstract: Although the kidney represents a target for the accumulation and toxicity of arsenic, little is known about the molecular targets of arsenic in this organ. Therefore, these studies were designed to examine the molecular impact of arsenite [As(III)] and arsenate [As(V)] at low (nanomolar) concentrations. Precision-cut rabbit renal cortical slices were challenged with As(III) or As(V) for up to 8 h. Neither form of the metal induced overt cytotoxicity as assessed by intracellular K+ levels over this time period at concentrations from 0.01-10 microM. In addition, no alterations in the expression of Hsp 60, 70, or 90 were observed. However, induction of heme oxygenase-1 (Hsp 32) was seen following a 4-h challenge with As(III), but not with As(V). As(III) and As(V) induced DNA binding of AP-1 at 2- and 4-h exposure; following a 6-h exposure there was no difference. Although no alteration in the DNA binding activity of ATF-2 was induced by As(III) or As(V), both forms enhanced the DNA binding activity of Elk-1. Enhanced DNA binding activity of AP-1 and Elk-1 correlated with increased gene expression of c-fos, but not c-jun, at 2 h. c-myc gene expression was also induced by As(III) and As(V), albeit at a later time point (6 h). These results suggest that acute arsenic challenge, by either As(III) or As(V), is associated with discrete alterations in the activity of signaling pathways and gene expression in renal tissue.",
Arsenic,1579330,"Concentrations of mercury, lead, chromium, cadmium, arsenic and aluminum in irrigation water wells and wastewaters used for agriculture in Mashhad, northeastern Iran Abstract: <strong>BACKGROUND: </strong>Contamination of water by toxic chemicals has become commonly recognized as an environmental concern. Based on our clinical observation in Mashhad, northeastern Iran, many people might be at risk of exposure to high concentrations of toxic heavy metals in water. Because wastewater effluents as well as water wells have been commonly used for irrigation over the past decades, there has been some concern on the toxic metal exposure of crops and vegetables irrigated with the contaminated water.<br /><br /><strong>OBJECTIVE: </strong>To measure the concentrations of mercury, lead, chromium, cadmium, arsenic and aluminium in irrigation water wells and wastewaters used for agriculture in Mashhad, northeastern Iran.<br /><br /><strong>METHODS: </strong>36 samples were taken from irrigation water wells and a wastewater refinery in North of Mashhad at four times--May 2008, March 2009, and June and July 2010. Atomic absorption spectrometry was used to measure the concentration of toxic metals. Graphite furnace was used for the measurement of lead, chromium, cadmium and aluminum. Mercury and arsenic concentrations were measured by mercury/hydride system.<br /><br /><strong>RESULTS: </strong>Chromium, cadmium, lead and arsenic concentrations in the samples were within the standard range. The mean±SD concentration of mercury in irrigation wells (1.02±0.40 ?g/L) exceeded the FAO maximum permissible levels. The aluminum concentration in irrigation water varied significantly from month to month (p=0.03). All wastewater samples contained high mercury concentrations (6.64±2.53 ?g/L).<br /><br /><strong>CONCLUSION: </strong>For high mercury and aluminum concentrations, the water sources studied should not be used for agricultural use. Regular monitoring of the level of heavy metals in water and employing the necessary environmental interventions in this area are strongly recommended.",
Arsenic,2064281,"Improvised condom catheter with a draining channel for management of atonic post partum haemorrhage Abstract: Primary postpartum haemorrhage (PPH) is one of the five leading causes of maternal mortality in both developed and developing countries [1] . During the last two decades various uterine taponade devices have been used successfully in the management of PPH [2-5]. Success rates for the control of postpartum bleeding have ranged from 71% to 87% [6, 7]. So far, the Bakri balloon is the only balloon product that is specifically designed for 'the control of postpartum uterine bleeding' (Cook Medical; enclosed instruction leaflet J-SOS1106). It has a drainage lumen which allows real-time assessment of ongoing blood loss above the level of the bulb and may prevent delayed treatment. This advantage is not present in the condom catheter. We report an improvised version of the condom catheter with a draining channel which was successfully used to manage two cases of PPH with uterine atony.",
Arsenic,2337092,"Environmental geochemistry and sources of potentially toxic elements in thermal springs in the Sabalan volcanic field, NW Iran Abstract: Thermal springs are attractive geological features interesting for tourists because of their balneological and therapeutic applications. In Iran, the thermal springs surrounding Mount Sabalan are famous and unique in this regard. Two clusters of thermal springs consisting of 16 springs and mostly used as spas occur in Neer and Meshkinshahr areas. In order to investigate the seasonal changes of field and chemical parameters and to trace element concentrations in dry and wet seasons, springs were sampled twice in May and November. Field data including T, EC, pH and Q were measured on-site and major cations and anions were analysed in the laboratory along with 72 trace elements. Cations show the following order of abundance: Na a parts per thousand &lt;&lt; Ca a parts per thousand yen K &gt; Mg and anions follow the order of Cl &gt; HCO3 &gt; SO4. Trace element concentrations indicate that most of the elements show concentrations well beyond the standard guideline values for drinking water. pH, T, spring discharge and elevation are not correlated with each other and with other parameters, indicating that they have had no role on concentrating or depleting trace elements in spring waters. While the two sets of samples were taken within a 6 month interval, the elements and parameters show slight or no variation from the first period to the second and in some cases, they show less than 5 % decrease or increase in the second sampling period. Correlation coefficient and principal component analysis of analytical data indicate that EC, K, Cl, HCO3, As, B, Ba, Br, Li, Na, Rb, Sr and V show very strong mutual correlation coefficients implying their relationship and common source and fate in the hydrothermal fluid that carries them out of the geothermal system. Moreover, they all fall in the component 1 of PCA. This group of elements is supposed to be derived from the magmatic-hydrothermal system through the interaction of hydrothermal fluids with the rocks they have passed through. The mean As value is 160-fold higher than the guideline values (10 mu g/l) and Mn and Sb shows an exceedance of 12- and 11.5-fold, respectively. Arsenic shows a variation of 5-5,834 mu g/l. Hence, it is supposed that potentially toxic elements may have adverse effects on tourists using the springs as a treatment or recreation. Indeed, the discharge of springs with high values of As and other elements represents a threat for downstream water uses. The higher concentrations of most elements including As, Pb, S, Cl and Sb and the higher pH values found in Neer area springs seem to be more related to an older hydrothermal system present in this area than the Meshkinshahr system that is still active today.",
Arsenic,736354,"Micronucleus frequency in peripheral blood lymphocytes and buccal mucosa cells of copper smelter workers, with special regard to arsenic exposure Abstract: Occupational exposure in copper smelters may produce various adverse health effects including cancer which, according to available epidemiologic data, is associated mainly with exposure to arsenic. Despite a number of well-documented studies reporting an increased risk of cancer among copper smelters workers, the data on genotoxic effects in this industry are scarce. In view of the above, an assessment of micronuclei (MN) frequency in peripheral blood lymphocytes and buccal epithelial cells from copper smelter workers was undertaken. Additionally, the clastogenic/aneugenic effect in lymphocytes was assessed with the fluorescence in situ hybridization (FISH). The study was conducted in three copper smelters in southwestern Poland. The subjects (n = 72) were enrolled among male workers at departments where As concentration in the air was up to at 80 microg/m(3). Exposure was assessed by measurement of arsenic concentration in urine and toenail samples. The control group (n = 83) was recruited from healthy male individuals living in central Poland who did not report any exposure to known genotoxins. The results of our study showed a significant increase in MN frequency in peripheral blood lymphocytes and in buccal epithelial cells of smelter workers, compared to the controls (7.96 +/- 4.28 vs. 3.47 +/- 1.70 and 0.98 +/- 0.76 vs. 0.50 +/- 0.52, respectively). The FISH technique revealed the presence of clastogenic and aneugenic effects in peripheral blood lymphocytes in both groups. The clastogenic effect was slightly more pronounced in the smelter workers; however, the difference was not statistically significant. The mean arsenic concentrations in urine (total arsenic species) and in toenail samples in the exposed group were 54.04 +/- 42.26 microg/l and 7.63 +/- 7.24 microg/g, respectively, being significantly different from control group 11.01 +/- 10.84 microg/l and 0.51 +/- 0.05 microg/g. No correlation between As content in urine or toenail samples and the genotoxic effect was found under study.",
Arsenic,1355149,MULTIPLE BASAL-CELL CARCINOMAS AND A MENINGIOMA AFTER LONG-TERM ARSENIC THERAPY Abstract: ,
Arsenic,1032295,"Modification of clastogenicity of three known clastogens by garlic extract in mice in vivo Abstract: The anticlastogenic activity of crude extract of garlic (Allium sativum L.) was studied in bone marrow cells of mice. Male laboratory-bred Swiss albino mice were given one of three concentrations of the freshly prepared extract (100 mg, 50 mg, and 25 mg/kg body weight) as a dietary supplement by gavage for 6 consecutive days. On the seventh day the mice were administered a single acute dose of two known clastogens, mitomycin C(1.5 mg/kg) and cyclophosphamide (25 mg/kg) or sodium arsenite (2.5 mg/kg), simultaneously with garlic extract. After 24 hr, chromosome preparations were made from the bone marrow cells. The endpoint studied were chromosomal aberrations and damaged cells. Garlic extract alone induced a low level of chromosomal damage. The clastogenicity of all three mutagens were reduced significantly in the animals which had been given garlic extract as dietary supplement. The extent of reduction was different for the three clastogens and may be attributed to the interaction with the different components of the extract.",1
Arsenic,2347759,The arsenic and mercury-containing Tanjore pills used in treating snake bites in the 18th century Madras Presidency Abstract: ,
Arsenic,710956,"Increased risk of QT prolongation associated with atherosclerotic diseases in arseniasis-endemic area in southwestern coast of Taiwan Abstract: Chronic arsenic exposure has been documented to be associated with various cardiovascular diseases. We aimed to investigate 1) the increased risk of QT prolongation in chronic arsenic exposure, and 2) the relationships of cardiac repolarization (QT interval duration) with ischemic heart disease and carotid atherosclerosis. We studied 280 men and 355 women living in the endemic area of arseniasis in southwestern Taiwan. QT intervals in electrocardiogram and carotid intima-media thickness (IMT) by ultrasonography were measured. Ischemic heart disease was diagnosed by history or abnormal electrocardiogram. Significant associations of the corrected QT interval (QTc) duration with ischemic heart disease and carotid intima-medium thickness and plaque were observed after adjustment for various risk factors in the multiple linear regression analysis (all p values &lt;0.05). Three indices of chronic arsenic exposure were all significantly associated with the risk of QTc prolongation showing dose-response relationships (p&lt;0.001). Chronic arsenic exposure was dose-dependently associated with the risk of QTc prolongation. Ischemic heart disease and carotid atherosclerosis were significantly associated with QTc intervals in chronic arsenic exposure. QTc prolongation might be suggested as an early biomarker for ischemic heart disease or carotid atherosclerosis in population with previous exposure to arsenic.",
Arsenic,1519195,"Arsenic in eggs and excreta of laying hens in Bangladesh: A preliminary study Abstract: The aim of this study was to detect arsenic concentrations in feed, well-water for drinking, eggs, and excreta of laying hens in arsenic-prone areas of Bangladesh and to assess the effect of arsenic-containing feed and well-water on the accumulation of arsenic in eggs and excreta of the same subject. One egg from each laying hen (n=248) and its excreta, feed, and well-water for drinking were collected. Total arsenic concentrations were determined by atomic absorption spectrophotometer, coupled with hydride generator. Effects of arsenic-containing feed and drinking-water on the accumulation of arsenic in eggs and excreta were analyzed by multivariate regression model, using Stata software. Mean arsenic concentrations in drinking-water, feed (dry weight [DW]), egg (wet weight [WW]), and excreta (DW) of hens were 77.3, 176.6, 19.2, and 1,439.9 ppb respectively. Significant (p<0.01) positive correlations were found between the arsenic contents in eggs and drinking-water (r=0.602), drinking-water and excreta (r=0.716), feed and excreta (r=0.402) as well as between the arsenic content in eggs and the age of the layer (r=0.243). On an average, 55% and 82% of the total variation in arsenic contents of eggs and excreta respectively could be attributed to the variation in the geographic area, age, feed type, and arsenic contents of drinking-water and feed. For each week's increase in age of hens, arsenic content in eggs increased by 0.94%. For every 1% elevation of arsenic in drinking-water, arsenic in eggs and excreta increased by 0.41% and 0.44% respectively whereas for a 1% rise of arsenic in feed, arsenic in eggs and excreta increased by 0.40% and 0.52% respectively. These results provide evidence that, although high arsenic level prevails in well-water for drinking in Bangladesh, the arsenic shows low biological transmission capability from body to eggs and, thus, the value was below the maximum tolerable limit for humans. However, arsenic in drinking-water and/or feed makes a significant contribution to the arsenic accumulations in eggs and excreta of laying hens.",
Arsenic,1017788,"Acute selenium poisoning by paradise nuts (Lecythis ollaria) Abstract: Two previously healthy women developed nausea, vomiting, headache and dizziness for several days, a massive hair loss about 2 weeks later and a discoloration of the fingernails. Detailed diagnostic procedures did not reveal any pathological results. Therapeutic measures did not show any effect. Thallium and arsenic were within normal range in plasma. Delayed quantitative determination of selenium in blood, however revealed toxic values (in case I: 479 microg/L of serum, 8 weeks after ingestion, and in case II 300 microg/L of serum, 9 weeks after ingestion). In retrospect, a relation to the ingestion of paradise nuts could be established.",
Arsenic,2278507,"Simultaneous determination of mercury and antimony in lead-base alloys by hydride generation-double channel atomic fluorescence spectrometry with solid-phase extraction using amberlite XAD-16 resin micro-column Abstract: The simultaneous determination of inorganic mercury and antimony was evaluated by the application in lead-base alloys through solid-phase extraction (SPE) coupled with hydride generation-double channel atomic fluorescence spectrometry (HG-DC-AFS) using a separation/preconcentration step on an Amberlite XAD-16 resin packed column. The high selective SPE was based on the similar properties between non-polar resins and molecular covalent compounds e.g., HgBr2 and SbBr3 formed in concentrated H2SO4 and HBr media. Various experimental conditions affecting the solid-phase extraction and determination of the analytes had been investigated. Under the optimized conditions, the limits of detection of 0.17 ?g L-1 for Hg(II) and 1.66 ?g L-1 for Sb(III) were obtained. The precisions (RSD) for seven replicate measurements of 20 ?g L-1 Hg(II) and Sb(III) were 0.37 and 2.9 %, respectively. The developed method was validated by spike test and was applied to the separation/preconcentration of Hg and Sb from two lead-base alloys matrices.",
Arsenic,1337473,"Placental concentrations of mercury, lead, cadmium, and arsenic and the risk of neural tube defects in a Chinese population Abstract: To examine whether in utero exposure to mercury (Hg), cadmium (Cd), lead (Pb) and arsenic (As) is associated with an elevated neural tube defects (NTDs) risk, placental concentrations of total Hg, Cd, Pb and As were measured with an inductively coupled plasma mass spectrometer (ICP-MS) in 36 anencephaly and 44 spina bifida cases as well as in 50 healthy controls. The median Hg concentration in the NTD cases (2.25ng/g) was higher than that of the controls (1.16ng/g). The odds ratio (OR) for an Hg concentration above the median was 8.80 (95% CI, 3.80-20.36) for the NTD cases. NTD risks increased for the second and third high levels of the concentrations, with ORs of 2.70 (95% CI, 1.13-6.43) and 18.20 (95% CI, 5.45-60.73), respectively. Therefore, higher placental levels of Hg are associated with an elevated risk of NTDs.",
Arsenic,2279592,"Concentrations of selected heavy metals in maternal blood and associated factors in rural areas in Shanxi Province, China Abstract: <strong>BACKGROUND: </strong>Animal experiments indicate that prenatal exposure to mercury (Hg), lead (Pb), cadmium (Cd) and arsenic (As) can induce fetal neural tube defects (NTDs). The objectives of this study were to determine the levels of maternal exposure to Hg, Pb, Cd and As during early pregnancy in rural areas of Shanxi Province, China, in order to explore factors that were associated with the concentrations of these metals in blood.<br /><br /><strong>METHODS: </strong>In 2010, we studied 215 pregnant women during their first and second trimesters in two counties with different prevalence levels of NTDs in Shanxi Province, China. Demographic and exposure data were collected from questionnaires. Blood concentrations of Hg, Pb and Cd were measured with ICP-MS; the As concentration was measured using atomic fluorescence spectrophotometry (AFS) in whole-blood specimens.<br /><br /><strong>RESULTS: </strong>The median concentrations of Hg, Pb, Cd and As in maternal blood were 0.26?g/L (interquartile range [IQR]: 0.16-0.45), 24.48?g/L (IQR: 18.72-32.31), 0.47?g/L (IQR: 0.33-0.67) and 0.52?g/L (IQR: 0.32-0.71), respectively. The maternal blood level of Cd was higher in Yushe county (median: 0.54?g/L) than in Daixian county (0.39?g/L). Women who lived near a coal combustion factory, used coal as cooking fuel, consumed fish, shrimp or shellfish, and consumed pork, beef or mutton during the week before the investigation had higher blood concentrations of Hg and As than their counterparts (P<0.05) after controlling for confounding variables, including the county of residence, in the logistic regression models.<br /><br /><strong>CONCLUSIONS: </strong>Blood levels of Cd were higher in Yushe county, which has a higher prevalence of neural tube defects. Higher maternal blood levels of Hg in pregnant women were associated with coal combustion. Higher maternal blood levels of Hg and As were associated with fish, shrimp or shellfish consumption, as well as pork, beef or mutton consumption.",
Arsenic,2278874,"ERCC1 expression as a predictive marker of cervical cancer treated with cisplatin-based chemoradiation Abstract: <strong>AIM: </strong>The purpose of the present study was to evaluate the correlation between repair cross-complementing group-1 (ERCC1) status and the outcome of platin-based chemoradiation of locally advanced cervical cancer.<br /><br /><strong>PATIENTS AND METHODS: </strong>Tumor specimens from 112 patients with locally advanced cervical cancer were evaluated for ERCC1 expression. The outcome of these patients was retrospectively assessed in correlation with ERCC1 expression.<br /><br /><strong>RESULTS: </strong>Increased expression of ERCC1 correlates with a better prognosis of cervical cancer. The 2-year overall survival was 68.6% in the group with low H-score for ERCC-1 and gradually increased in the intermediate and high H-score groups to 71.7% and 90.7%, respectively.<br /><br /><strong>CONCLUSION: </strong>The present study did not confirm the correlation of low levels of ERCC1 expression with unfavorable outcomes of patients with locally advanced cervical cancer treated with platin-based radiochemotherapy.",
Arsenic,1016020,"Manganese exposure from drinking water and children's classroom behavior in Bangladesh Abstract: <strong>BACKGROUND: </strong>Evidence of neurological, cognitive, and neuropsychological effects of manganese (Mn) exposure from drinking water (WMn) in children has generated widespread public health concern. At elevated exposures, Mn has been associated with increased levels of externalizing behaviors, including irritability, aggression, and impulsivity. Little is known about potential effects at lower exposures, especially in children. Moreover, little is known regarding potential interactions between exposure to Mn and other metals, especially arsenic (As).<br /><br /><strong>OBJECTIVES: </strong>We conducted a cross-sectional study of 201 children to investigate associations of Mn and As in tube well water with classroom behavior among elementary school children, 8-11 years of age, in Araihazar, Bangladesh.<br /><br /><strong>METHODS: </strong>Data on exposures and behavioral outcomes were collected from the participants at the baseline of an ongoing longitudinal study of child intelligence. Study children were rated by their school teachers on externalizing and internalizing items of classroom behavior using the standardized Child Behavior Checklist-Teacher's Report Form (CBCL-TRF).<br /><br /><strong>RESULTS: </strong>Log-transformed WMn was positively and significantly associated with TRF internalizing [estimated ? = 0.82; 95% confidence interval (CI), 0.08-1.56; p = 0.03], TRF externalizing (estimated ? = 2.59; 95% CI, 0.81-4.37; p =0.004), and TRF total scores (estimated ? = 3.35; 95% CI, 0.86-5.83; p = 0.008) in models that adjusted for log-transformed water arsenic (WAs) and sociodemographic covariates. We also observed a positive monotonic dose-response relationship between WMn and TRF externalizing and TRF total scores among the participants of the study. We did not find any significant associations between WAs and various scales of TRF scores.<br /><br /><strong>CONCLUSION: </strong>These observations reinforce the growing concern regarding the neurotoxicologic effects of WMn in children.",
Arsenic,2337176,"Comparing trace metal bioaccumulation characteristics of three freshwater decapods of the genus Macrobrachium Abstract: Potential sources and kinetics of metal bioaccumulation by the three Macrobrachium prawn species M. australiense, M. rosenbergii and M. latidactylus were assessed in laboratory experiments. The prawns were exposed to two scenarios: cadmium in water only; and exposure to metal-rich mine tailings in the same water. The cadmium accumulation from the dissolved exposure during 7 days, followed by depuration in cadmium-free water for 7 days, was compared with predictions from a biokinetic model that had previously been developed for M. australiense. M. australiense and M. latidactylus accumulated significant tissue cadmium during the exposure phase, albeit with different uptake rates. All three species retained &gt;95% of the bioaccumulated cadmium during the depuration phase, indicating very slow efflux rates. Following exposure to tailings, there were significant (p&lt;0.05) differences in tissue arsenic, cadmium, lead and zinc concentrations among species. Cadmium and zinc concentrations were increased relative to controls for all three species but were not different between treatments (direct/indirect contact with tailings), suggesting these metals were primarily accumulated via the dissolved phase. All species bioaccumulated significantly greater arsenic and lead when in direct contact with mine tailings, demonstrating the importance of an ingestion pathway for these metals. Copper was not bioaccumulated above control concentrations for any species. The differences between the metal accumulation of the three prawns indicated that a biokinetic model of cadmium bioaccumulation for M. australiense could potentially be used to describe the metal bioaccumulation of the other two prawn species, albeit with an over-prediction of 3-9 times. Despite these being the same genus of decapod crustacean, the study highlights the issues with using surrogate species, even under controlled laboratory conditions. It is recommended that future studies using surrogate species quantify the metal bioaccumulation characteristics of each species in order to account for any differences between species.",
Arsenic,1348016,"Geochemistry of surface sediments in tsunami-affected Sri Lankan lagoons regarding environmental implications Abstract: The December 26, 2004 Indian Ocean tsunami was one of the largest in human history, devastating the coastal wetlands of surrounding countries. This study present the chemical analyses of tsunamigenic and pre-tsunami sediments from Hikkaduwa and Hambantota lagoons in southern Sri Lanka, to assess their geochemical composition, their source, and subsequent environmental impacts. Principal component analysis of the tsunami sediments shows that 42% of the total variance is accounted for calcium oxide and Sr. That is, the tsunami deposits are rich in biogenic phases derived from shallow marine sediments. High organic matter contents of the tsunami sediments of up to 80 wt% also support this interpretation. The association of chlorine (<9.4 wt%), brome (<170 mg/kg), arsenic (<17 mg/kg), iron (III) oxide (<12.9 wt%) and sulfur (<7.6 wt%) accounts for 33% of the variance, reflecting higher salinity. This further suggests that the sediments were mainly derived from a marine environment, rather than from non-marine sands and/or soils. Immobile element contents and relations (thorium, scandium and zirconium) suggest that the tsunami sediment source was mostly felsic in composition, with some mafic component, and mixed with predominantly shallow marine shelf or slope sediments. Additional compositional variations in the tsunami sediments in both lagoons may be associated with variations of wave strength along the coast and by the morphology of the continental shelf. Lower elemental abundances in Hambantota lagoon sediments compared to Hikkaduwa equivalents may thus reflect a greater non-marine component in the former, and greater shelf sediment component in the latter.",
Arsenic,1021728,"Sodium arsenite induced reactive oxygen species generation, nuclear factor (erythroid-2 related) factor 2 activation, heme oxygenase-1 expression, and glutathione elevation in Chang human hepatocytes Abstract: Liver is one of the major target organs of arsenic toxicity and carcinogenesis. Nuclear factor (erythroid-2 related) factor 2 (Nrf2) is a redox-sensitive transcription factor, regulating critically cellular defense responses against the toxic metallic arsenic in many cell types and tissues. This study was conducted to evaluate the hepato-cellular Nrf2 and Nrf2-regulated antioxidant reactions of sodium arsenite exposure in Chang human hepatocytes. Nrf2 and heme oxygenase-1 (HO-1) protein levels were detected by Western blot, and Nrf2-regulated HO-1 mRNA expressions were determined using semiquantitative RT-PCR by 0?50 ?mol/L of sodium arsenite exposure for 2, 6, 12, and 24 h. We also observed the changes of intracellular reactive oxygen species (ROS) and total cellular glutathione (GSH) by flow cytometry and spectrophotometry, respectively. Our results showed that intracellular ROS were both dose- and time-dependent induced by inorganic arsenic; Cellular Nrf2 protein levels increased rapidly after 2 h of exposure, elevated significantly at 6 h, and reached the maximum at 12 h. The endogenous Nrf2-regulated downstream HO-1 mRNA and protein were also induced dramatically and lasted for as long as 24 h. In addition, intracellular GSH levels elevated in consistent with Nrf2 activation. Our findings here suggest that inorganic arsenic alters cellular redox balance in hepatocytes to trigger Nrf2-regulated antioxidant responses promptly, which may represent an adaptive cell defense mechanism against inorganic arsenic induced liver injuries and hepatoxicity.",
Arsenic,1025783,"p53 response to arsenic exposure in epithelial cells: protein kinase B/Akt involvement Abstract: Inorganic arsenic is a major environmental contaminant associated with an increased risk of human skin cancer. Arsenic modulates cellular signaling pathways that affect diverse processes such as cell proliferation, differentiation, and apoptosis, including genotoxic damage. The p53 protein plays a central role in mediating stress and DNA damage responses, leading to either growth arrest or apoptosis. Several signal transduction pathways activated under a plethora of stressing conditions increase p53 protein levels. To further understand the molecular mechanisms involved in the arsenic mode of action, we explored the effects of this metalloid on the activation of the phosphatidyl inositol 3-kinase (PI3K)/Ca2+/diacylglicerol dependent protein kinase/protein kinase B (PKB) signaling cascade and its repercussion in p53 activation in two epithelial cell types: primary normal human keratinocytes cultures (NHK) and the carcinoma-derived C33-A cell line. Although in both cell systems arsenic leads to an increase in p53 and its binding to DNA, the final outcome is different. In NHK, arsenic triggers a sustained activation of the PI3K/PKB/glycogen synthase kinase-3 beta pathway, driving the cell into a cell-differentiated stage in which the proliferation signals are turned down. In sharp contrast, in C33-A cells, arsenic leads to a transient increase in p53 followed by a drastic reduction in its nuclear levels and an increase in cell proliferation. These findings favor the notion that p53-stage and transcriptional abilities are important to understand modifications in the proliferation-differentiation balance, an equilibrium that is severely impaired by arsenic.",
Arsenic,2337146,"An integrative study of the genetic, social and environmental determinants of chronic kidney disease characterized by tubulointerstitial damages in the North Central Region of Sri Lanka Abstract: Objectives: Previous investigations on chronic kidney disease of unknown etiology characterized by tubulointerstitial damages (CKDu) in the North Central Region (NCR) of Sri Lanka have supported the involvement of social, environmental and genetic factors in its pathogenesis. Methods: We conducted a social-environmental-and-genetic epidemiology study on a male population in NCR to investigate the genetic and environmental contributors. We recruited 311 case-series patients and 504 control candidates. Of the 504 control candidates, 218 (43%) were eliminated because of the presence of hypertension, proteinuria, high HbA1c, high serum creatinine or high alpha-1 microglobulin in urine. Results and Discussion: None of 18 metals measured (mu g/l) in urine, including Cd, As and Pb, showed significantly higher concentrations in cases compared with controls. As speciation results showed that 75-80% of total urinary As was in the form of arsenobetaine, which is non-toxic to humans. None of the metal concentrations in drinking water samples exceeded guideline values. A genome-wide association study (GWAS) was conducted to determine the genetic contributors. The GWAS yielded a genome-wide significant association with CKDu for a single nucleotide polymorphism (SNP; rs6066043; p=5.23 x 10(-9) in quantitative trait locus analysis; p=3.73 x 10(-9) in dichotomous analysis) in SLC13A3 (sodium-dependent dicarboxylate transporter member 3). The population attributable fraction and odds ratio for this SNP were 50% and 2.13. Genetic susceptibility was identified as the major risk factor for CKDu. However, 43% of the apparently healthy male population suffers from non-communicable diseases, suggesting their possible influence on CKDu progression.",
Arsenic,2347768,"Acid and organic resistant nano-hydrated zirconium oxide (HZO)/polystyrene hybrid adsorbent for arsenic removal from water Abstract: Hydrous zirconium oxide (HZO)-originated nanocomposite adsorbent of excellent stability against pH variation and organic ligands was fabricated for efficient arsenic removal from water. The nanocomposite adsorbent HZO-201 was obtained by encapsulating nanosized HZO particles inside a polystyrene anion exchanger D201. Negligible metal dissolution was observed from HZO-201 in solution of acidic pHs (to similar to 1) and oxalate at high levels, while significant metal leaching occurred from a similar hydrated ferric oxide-based nanocomposite HFO-201of the same host. Arsenate adsorption by HZO-201 is a pH-dependent process with maximum capacity of 88.74 mg/g at pH 7.0 +/- 0.1, comparable to HFO-201 under similar conditions. As compared to sulfate, chloride, and bicarbonate, silicate and phosphate could inhibit arsenic uptake more strongly by HZO-201. Fixed-bed adsorption indicated that arsenate in simulated groundwater could be effectively captured from 100 gg/L to &lt;10 mu g/L within 2600 BV (bed volume), and that in a real acidic mining effluent could be removed from 750 mu g/L to &lt;50 mu g/L within 2900 By. The exhausted HZO-201 was also amenable to efficient regeneration with a binary NaCI-NaOH solution for repeated use without any significant capacity loss. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,2215724,"p16INK4a reporter mice reveal age-promoting effects of environmental toxicants Abstract: While murine-based systems to identify cancer-promoting agents (carcinogens) are established, models to identify compounds that promote aging (gerontogens) have not been described. For this purpose, we exploited the transcription of p16INK4a, which rises dynamically with aging and correlates with age-associated disease. Activation of p16INK4a was visualized in vivo using a murine strain that harbors a knockin of the luciferase gene into the Cdkn2a locus (p16LUC mice). We exposed p16LUC mice to candidate gerontogens, including arsenic, high-fat diet, UV light, and cigarette smoke and serially imaged animals to monitor senescence induction. We show that exposure to a high-fat diet did not accelerate p16INK4a expression, whereas arsenic modestly augmented, and cigarette smoke and UV light potently augmented, activation of p16INK4a-mediated senescence. This work provides a toxicological platform to study mammalian aging and suggests agents that directly damage DNA promote molecular aging.",
Arsenic,1070450,"Cross-regulations among NRFs and KEAP1 and effects of their silencing on arsenic-induced antioxidant response and cytotoxicity in human keratinocytes Abstract: BACKGROUND: Nuclear factor E2-related factors (NRFs), including NRF2 and NRF1, play critical roles in mediating the cellular adaptive response to oxidative stress. Human exposure to inorganic arsenic, a potent oxidative stressor, causes various dermal disorders, including hyperkeratosis and skin cancer. OBJECTIVE: We investigated the cross-regulations among NRF2, NRF1, and KEAP1, a cullin-3-adapter protein that allows NRF2 to be ubiquinated and degraded by the proteasome complex, in arsenic-induced antioxidant responses. RESULTS: In human keratinocyte HaCaT cells, selective knockdown (KD) of NRF2 by lentiviral short hairpin RNAs (shRNAs) significantly reduced the expression of many antioxidant enzymes and sensitized the cells to acute cytotoxicity of inorganic arsenite (iAs(3+)). In contrast, silencing KEAP1 led to a dramatic resistance to iAs(3+)-induced apoptosis. Pretreatment of HaCaT cells with NRF2 activators, such as tert-butylhydroquinone, protects the cells against acute iAs(3+) toxicity in an NRF2-dependent fashion. Consistent with the negative regulatory role of KEAP1 in NRF2 activation, KEAP1-KD cells exhibited enhanced transcriptional activity of NRF2 under nonstressed conditions. However, deficiency in KEAP1 did not facilitate induction of NRF2-target genes by iAs(3+). In addition, NRF2 silencing reduced the expression of KEAP1 at transcription and protein levels but increased the protein expression of NRF1 under the iAs(3+)-exposed condition. In contrast, silencing KEAP1 augmented protein accumulation of NRF2 under basal and iAs3+-exposed conditions, whereas the iAs(3+)-induced protein accumulation of NRF1 was attenuated in KEAP1-KD cells. CONCLUSIONS: Our studies suggest that NRF2, KEAP1, and NRF1 are coordinately involved in the regulation of the cellular adaptive response to iAs(3+)-induced oxidative stress.",
Arsenic,1355870,"Expression of tumor suppressor gene product p14ARF in endometrioid adenocarcinoma of the uterine corpus Abstract: p14 activates p53 by inhibiting MDM2 expression and arrests the cell cycle in G1 and G2/M. Abnormal p14 expression has been reported in various human cancers. This study investigated p14 expression in endometrioid adenocarcinoma of the uterine corpus in an attempt to clarify its correlation with other cell cycle-regulators and clinicopathologic parameters. The specimen studied consisted of 124 endometrioid adenocarcinomas, 20 normal endometria, and 20 endometrial hyperplasias. Immunohistochemical staining of formalin-fixed and paraffin-embedded tissues was performed using a Catalyzed Signal Amplification System. Cells with &gt;5% positive staining were classified as positive for p14. A staining score of 1 was adopted when the percentage of positive nuclei was &lt;5%, a score of 2 when it was 5 to 50%, and a score of 3 when it was &gt;50%. In normal endometrium, the frequency of positive staining in the proliferative phase and secretory phase was 50% (4/8) and 58.3% (7/12), with staining scores of 1.8+/-0.9 and 1.6+/-0.5, respectively. The frequency of staining in simple hyperplasia (SH), complex hyperplasia (CH), and complex atypical hyperplasia (CAH) was 88.9% (8/9), 25% (1/4), and 42.9% (3/7), respectively; the staining scores were 1.9+/-0.3, 1.3+/-0.5, and 1.4+/-0.5, respectively. Among endometrioid adenocarcinomas, the frequency of staining of well-differentiated (G1), moderately differentiated (G2), and poorly differentiated (G3) adenocarcinomas was 69% (49/71), 64% (16/25), and 42.9% (12/28) respectively, with staining scores of 2.1+/-0.8, 2+/-0.9, and 1.8+/-1, respectively. Thus expression levels of p14 were higher in G1 tumors than in normal endometria or endometrial hyperplasias, and the frequency of its staining in endometrioid carcinomas was inversely correlated with histologic grade. The staining score for endometrioid adenocarcinomas also was inversely correlated with the labeling index (LI) of Ki-67, but not with that of cyclin A, cyclin D1, cyclin E, cdk2, p27, p53, or other clinicopathologic parameters. In conclusion, p14 expression correlated with histologic grade and Ki-67, but not other prognostic factors in endometrioid adenocarcinoma. Long-term follow-up studies are needed to analyze the significance of p14 expression in these tumors.",
Arsenic,2278378,"A Sand Control and Development Model in Sandy Land Based on Mixed Experiments of Arsenic Sandstone and Sand: A Case Study in Mu Us Sandy Land in China Abstract: Serious desertification caused by human activity and climate change, in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land, lead to severe scarcity of soil and water resources, which causes worse local agricultural conditions accordingly. Many physical properties of arsenic sandstone is complementary with that of sand, arsenic sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land. Container experiments are carried out to study the enhancement of water holding capacity of the mixture, the blending ratio of arsenic sandstone and sand, and the proper size of the arsenic sandstone particles, respectively. The results of the experiments show that particle size of 4 cm with a ratio of 1:2 between arsenic sandstone and sand are the proper parameters on blending. Both water content and fertility increase after blending. Water use efficiency in the mixture is 2.7 times higher than that in sand by the water release curves from experiments. Therefore, a new sand control and development model, including arsenic sandstone blending with sand, efficient water irrigation management and reasonable farming system, is put forward to control and develop sandy land so that water-saving agriculture could be developed. Demonstration of potato planting about 153.1 ha in area in the Mu Us Sandy Land in China indicates that water consumption is 3018 m(3)/ha in the whole growth period. It means that about 61% of irrigation water can be saved compared with water use in coarse sand without treatment. Recycle economic mode and positive feedback of sand resource-crop planting-soil resource are constructed, which changes sand into arable soil and make it possible to develop water-saving agriculture on it. The proposed model will be helpful for soil-water resources utilization and management in the Mu Us Sandy Land.",
Arsenic,1015696,"Regulation of miRNA-21 by reactive oxygen species-activated ERK/NF-?B in arsenite-induced cell transformation Abstract: After acute exposure of cells to arsenic, reactive oxygen species mediate changes in cell behavior, including activation of proliferative signaling. For chronic exposure to arsenic, however, the function of reactive oxygen species in cell transformation remains poorly understood. Although microRNA-21 (miR-21) has been implicated in various aspects of carcinogenesis, its functions and molecular mechanisms in carcinogen-induced tumorigenesis are unclear. The purpose of this study was to determine if miR-21 is involved in arsenite-induced malignant transformation and to characterize the associated signaling pathways. During arsenite-induced transformation of human embryo lung fibroblast (HELF) cells, miR-21 was upregulated, and the extracellular signal-regulated kinase (ERK)/nuclear factor-?B (NF-?B) signal pathway was activated. Moreover, superoxide radical dismutase (a scavenger of superoxide) and catalase (a scavenger of hydroperoxides) blocked the arsenite-induced effects in HELF cells and mouse embryonic fibroblasts. Blockage of ERK by the inhibitor U0126 or inhibition of NF-?B p65 by siRNA or Bay 11-7082 prevented the increases in miR-21 and the decreases in Spry1, Pten, and Pdcd4, the target proteins of miR-21, induced by arsenite. As determined by a ChIP-qPCR assay, NF-?B p65 regulated miR-21 expression by binding directly to the promoter of miR-21. Further, anti-miR-21 downregulated miR-21 expression and prevented the arsenite-induced activation of ERK via the increase in Spry1, indicating that miR-21 has a feedback effect in regulating ERK activation. Overexpression of miR-21 with an miR-21 mimic and feedback activation of ERK and NF-?B via the decrease in Spry1 promoted the malignancy of HELF cells exposed to arsenite, but knockdown of miR-21 with anti-miR-21 and feedback blockage of ERK and NF-?B activation through an increase in Spry1 decreased anchorage-independent growth of arsenite-transformed cells. Thus, the transformation of HELF cells induced by chronic exposure to arsenite is mediated by increased miR-21 expression, which, in turn, is mediated by reactive oxygen species activation of the ERK/NF-?B pathway.",
Arsenic,1465755,"Arsenic exposure from drinking water and QT-interval prolongation: Results from the Health Effects of Arsenic Longitudinal Study Abstract: BACKGROUND: Arsenic exposure from drinking water has been associated with heart disease, but underlying mechanisms are uncertain. OBJECTIVE: To evaluate the association between history of arsenic exposure from drinking water and prolongation of heart rate-corrected QT (QTc), PR, and QRS intervals. METHOD: We conducted a study of 1,715 participants enrolled at baseline from the Health Effects of Arsenic Longitudinal Study. Arsenic exposure was measured in baseline well water and urine samples, and in urine samples collected during follow-up. Electrocardiogram evaluations were performed during 2005-2010, with an average time since baseline of 5.9 years. RESULTS: The adjusted odds ratio [95% confidence interval (CI)] for QTc prolongation, defined as a QTc ? 450 ms in men and ? 460 ms in women, was 1.17 (1.01, 1.35) for a 1-standard deviation (SD) increase in well water arsenic (108.7 µg/L). The positive association appeared to be limited to women, with adjusted odds ratios of 1.24 (95% CI: 1.05, 1.47) and 1.24 (95% CI: 1.01, 1.53) for a 1-SD increases in baseline well water and urinary arsenic, respectively, compared with 0.99 (95% CI: 0.73, 1.33) and 0.86 (95% CI: 049, 1.51) in men. There were no apparent associations of baseline well water arsenic or urinary arsenic with PR or QRS prolongation in women or men. CONCLUSIONS: Long-term arsenic exposure from drinking water (average 95 µg/L; range, 0.1-790 µg/L) was associated with subsequent QT-interval prolongation in women. Future longitudinal studies with repeated ECG measurements would be valuable to assess the influence of changes in exposure.",
Arsenic,2128204,"War on Carcinogens: Industry Disputes Human Relevance of Chemicals Causing Cancer in Laboratory Animals Based on Unproven Hypotheses, Using Kidney Tumors as an Example Abstract: Evidence from studies in animals is essential for identifying chemicals likely to cause or contribute to many diseases in humans, including cancers. Yet, to avoid or delay the implementation of protective public health standards, the chemical industry typically denies cancer causation by agents they produce. The spurious arguments put forward to discount human relevance are often based on inadequately tested hypotheses or modes of action that fail to meet Bradford Hill criteria for causation. We term the industry attacks on the relevance of animal cancer findings as the ""War on Carcinogens."" Unfortunately, this tactic has been effective in preventing timely and appropriate health protective actions on many economically important yet carcinogenic chemicals, including: arsenic, asbestos, benzene, 1,3-butadiene, formaldehyde, methylene chloride, phthalates, tobacco usage, trichloroethylene [TCE], and others. Recent examples of the ""War on Carcinogens"" are chemicals causing kidney cancer in animals. Industry consultants argue that kidney tumor findings in rats with exacerbated chronic progressive nephropathy (CPN) are not relevant to humans exposed to these chemicals. We dispute and dismiss this unsubstantiated claim with data and facts, and divulge unprofessional actions from a leading toxicology journal. [PUBLICATION ABSTRACT]",
Arsenic,1032276,"Assessment of arsenic exposures and controls in gallium arsenide production Abstract: The electronics industry is expanding the use of gallium arsenide in the production of optoelectronic devices and integrated circuits. Workers in the electronics industry using gallium arsenide are exposed to hazardous substances such as arsenic, arsine, and various acids. Arsenic requires stringent controls to minimize exposures (the current OSHA PEL for arsenic is 10 micrograms/m3 and the NIOSH REL is 2 micrograms/m3 ceiling). Inorganic arsenic is strongly implicated in respiratory tract and skin cancer. For these reasons, NIOSH researchers conducted a study of control systems for facilities using gallium arsenide. Seven walk-through surveys were performed to identify locations for detailed study which appeared to have effective controls; three facilities were chosen for in-depth evaluation. The controls were evaluated by industrial hygiene sampling. Including personal breathing zone and area air sampling for arsenic and arsine; wipe samples for arsenic also were collected. Work practices and the use of personal protective equipment were documented. This paper reports on the controls and the arsenic exposure results from the evaluation of the following gallium arsenide processes: Liquid Encapsulated Czochralski (LEC) and Horizontal Bridgeman (HB) crystal growing, LEC cleaning operations, ingot grinding/wafer sawing, and epitaxy. Results at one plant showed that in all processes except epitaxy, average arsenic exposures were at or above the OSHA action level of 5 micrograms/m3. While cleaning the LEC crystal pullers, the average potential arsenic exposure of the cleaning operators was 100 times the OSHA PEL. At the other two plants, personal exposures for arsenic were well controlled in LEC, LEC cleaning, grinding/sawing, and epitaxy operations.",
Arsenic,1597316,"Simultaneous Redox Conversion of Chromium(VI) and Arsenic(III) under Acidic Conditions Abstract: Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H2O2 enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards the oxidation of As(III), even though it enhances the reduction of Cr(VI). To explain these results we propose a reaction mechanism where Cr(VI) is primarily reduced to Cr(III) by H2O2, via the intermediate tetraperoxochromate Cr(V). Cr(V) is then involved in the formation of (•)OH radicals. In the presence of ligands, the capacity of Cr(V) to form (•)OH radicals, which are primarily responsible for As(III) oxidation, is practically inhibited. Our findings demonstrate the feasibility for the coconversion of As(III) and Cr(VI) in AMD and real-world constraints to this strategy for environmental remediation.",
Arsenic,1340056,"Thiamine deficiency in Cambodian infants with and without beriberi Abstract: OBJECTIVES: To test the hypothesis that heavy metal toxicity and consumption of thiaminase-containing foods predispose to symptomatic thiamine deficiency. STUDY DESIGN: In a case-control study, thiamine diphosphate (TDP) blood concentrations were measured in 27 infants diagnosed with beriberi at a rural clinic, as well as their mothers and healthy Cambodian and American controls. Blood and urine levels of lead, arsenic, cadmium, mercury, and thallium were measured. Local food samples were analyzed for thiaminase activity. RESULTS: Mean TDP level among cases and Cambodian controls was 48 and 56 nmol/L, respectively (P = .08) and was 132 nmol/L in American controls (P < .0001 compared with both Cambodian groups). Mean TDP level of mothers of cases and Cambodian controls was 57 and 57 nmol/L (P = .92), and was 126 nmol/L in American mothers (P < .0001 compared with both Cambodian groups). Cases (but not controls) had lower blood TDP levels than their mothers (P = .02). Infant TDP level decreased with infant age and was positively associated with maternal TDP level. Specific diagnostic criteria for beriberi did not correlate with TDP level. There was no correlation between heavy metal levels and either TDP level or case/control status. No thiaminase activity was observed in food samples. CONCLUSIONS: Thiamine deficiency is endemic among infants and nursing mothers in rural southeastern Cambodia and is often clinically inapparent. Neither heavy metal toxicity nor consumption of thiaminase-containing foods account for thiamine deficiency in this region.",
Arsenic,2278682,"Effectiveness of co-trimoxazole to prevent Plasmodium falciparum malaria in HIV-positive pregnant women in sub-Saharan Africa: An open-label, randomized controlled trial Abstract: Background. Human immunodeficiency virus (HIV) and malaria during pregnancy cause substantial perinatal mortality. As co-trimoxazole (CMX) protects children and HIV-positive adults against malaria, we compared the effectiveness of daily CMX with sulfadoxine-pyrimethamine intermittent preventive treatment (IPT-SP) on malaria risk in HIV-positive pregnant women in a Plasmodium falciparum-endemic African area. Methods. From January 2009 to April 2011, we included in a randomized noninferiority trial all HIV type 1-infected pregnant women (?28 weeks' gestation, CD4 count ?200 cells/µL, hemoglobin level ?7 g/L) in 19 health centers in Togo. Women were randomly assigned to daily 800 mg/160 mg CMX, or IPT-SP. The primary outcome was the proportion of malaria-free pregnancies. Other outcomes included malaria incidence, parasitemia, placental malaria, anemia, and infants' birth weight. Results. Of 264 women randomly assigned to the CMX or IPT-SP group, 126 of 132 and 124 of 132, respectively, were included in the analysis. There were 33 confirmed cases of clinical malaria among 31 women in the CMX group, and 19 among 19 women in the IPT-SP group. Ninety-five of 126 (75.4%) women in the CMX group and 105 of 124 (84.7%) in the IPT-SP group remained malaria-free during their pregnancy (difference, 9.3%; 95% confidence interval [CI], -.53 to 19.1, not meeting the predefined noninferiority criterion). The incidence rate in intention-to-treat analysis was 108.8 malaria episodes per 100 person-years in CMX (95% CI, 105.4-112.2) and 90.1 in IPT-SP (95% CI, 86.8-93.4) (not significant). Prevalence of parasitemia was 16.7% in the CMX group vs 28% in the IPT-SP group (P = .02). Histology revealed 20.3% placental malaria in the CMX group vs 24.6% in the IPT-SP group (not significant). Grade 3-4 anemia was more frequent in the CMX group (10% vs 4%; P = .008). No pregnant women died. Median birth weight was similar. Conclusions. Daily CMX was not noninferior to IPT-SP for preventing maternal malaria but safe and at least similar regarding parasitemia or placental malaria and birth outcomes. Clinical Trials Registration. ISRCTN98835811.",
Arsenic,1015872,"Cord Blood Levels of Toxic and Essential Trace Elements and Their Determinants in the Terai Region of Nepal: A Birth Cohort Study Abstract: The purpose of this study is to evaluate the cord blood level of toxic and trace elements and to identify their determinants in Terai, Nepal. One hundred pregnant women were recruited from one hospital in Chitwan, Nepal in 2008. The cord blood levels of toxic [lead (Pb), arsenic (As), and cadmium (Cd)], essential trace elements [zinc (Zn), selenium (Se), and copper (Cu)], demographic, socioeconomic, and behavioral variables were measured. The mean values of Pb, As, Cd, Zn, Se, and Cu in cord blood level were found as 31.7, 1.46, 0.39, 2,286, 175, and 667 ?g/L, respectively. In the multivariate regression model, cord blood As levels from less educated mothers were higher than those from educated mothers (coefficient?=?-0.01, 95% confidence interval [CI]?=?-0.02-0.00). The maternal age was positively associated with the cord blood Cd level (coefficient?=?0.02, 95% CI?=?0.01-0.03), while it was negatively associated with the cord blood As level (coefficient?=?-0.01, 95% CI?=?-0.03--0.01). Cord blood levels of Pb, Zn, Se, and Cu were not associated with maternal age, socioeconomic status, living environment, and smoking status. As and Cd levels were relatively lower than those reported in previous studies in Asia, while the levels of Pb and the trace elements were similar. Less educated mothers are more likely to become a higher in utero As source to their fetus, and fetuses of older mothers were more likely to have higher in utero Cd exposure in Terai, Nepal.",
Arsenic,737608,"Health risk associated with dietary co-exposure to high levels of antimony and arsenic in the world's largest antimony mine area Abstract: Like arsenic (As), antimony (Sb) is known to be a genotoxic element in vitro and in vivo. Sb is now recognized as a global contaminant and has aroused the global concerns recently. However, knowledge is scarce concerning the transfer of Sb from the environment to humans and the related hazards to human health. In this pilot study, the health risk and main pathway of long-term human exposure to Sb and As for residents around Chinese Xikuangshan (XKS) Sb mine, the world's largest Sb mine, were evaluated by dietary exposure and hair accumulations survey. The concentrations and species of Sb and As in food samples (n=209) from three main categories and six subcategories, and in hair samples (n=89) were determined. Residents in the vicinity of XKS had an estimated dietary intake of Sb (554?g/day) which was 1.5 times higher than the tolerable daily intake (TDI) (Sb, 360?g/day), whereas their dietary intake of inorganic As (107?g/day) was slightly lower than the provisional tolerable weekly intake (PTWI) of 15?g/kg BW/week (equal to 129?g As/day). Hair Sb and As concentrations (Sb, 15.7mg/kg, DW; As, 3.99mg/kg, DW) in XKS residents are both above the normal/toxic level. Rice, vegetables (especially leafy vegetable), drinking water, and meat/poultry were the dominant dietary intake sources of Sb for the residents. In contrast, rice was the uniquely dominant dietary intake source of As. Antimonate (Sb(V)) was the dominant Sb species in vegetables, drinking water and residents' hairs. This study highlighted the difference of exposure characteristics between Sb and As. The preliminary results suggested that dietary exposures to Sb, rather than As, was the dominant health risk to local residents. Nevertheless, the adverse effects of As levels on the health of residents still can not be ignored since the elevated As concentrations in human hair have reached the critical level for health risks. In addition, this pilot study did not consider the possible Sb and As combined effects.",
Arsenic,1017355,"Fecal Contamination of Shallow Tubewells in Bangladesh Inversely Related to Arsenic Abstract: The health risks of As exposure due to the installation of millions of shallow tubewells in the Bengal Basin are known, but fecal contamination of shallow aquifers has not systematically been examined. This could be a source of concern in densely populated areas with poor sanitation because the hydraulic travel time from surface water bodies to shallow wells that are low in As was previously shown to be considerably shorter than for shallow wells that are high in As. In this study, 125 tubewells 6-36 m deep were sampled in duplicate for 18 months to quantify the presence of the fecal indicator Escherichia coli. On any given month, E. coli was detected at levels exceeding 1 most probable number per 100 mL in 19-64% of all shallow tubewells, with a higher proportion typically following periods of heavy rainfall. The frequency of E. coli detection averaged over a year was found to increase with population surrounding a well and decrease with the As content of a well, most likely because of downward transport of E. coli associated with local recharge. The health implications of higher fecal contamination of shallow tubewells, to which millions of households in Bangladesh have switched in order to reduce their exposure to As, need to be evaluated.",
Arsenic,1020065,"Dose-dependent biotransformation of arsenite in rats--not S-adenosylmethionine depletion impairs arsenic methylation at high dose Abstract: Arsenite (AsIII) is eliminated via excretion and methylation. Monomethylarsonous acid (MMAsIII) is a super toxic metabolite of AsIII, while dimethylarsinic acid produced in the next metabolic step is relatively atoxic. Since the role of methylation in the acute toxicity and elimination of AsIII in vivo is unclear, we have examined the excretion and tissue retention of AsIII and its metabolites in rats exposed to increasing AsIII doses. Rats were injected i.v. with 20, 50 and 125 micromol/kg AsIII and arsenic metabolites in bile, urine and tissues were analysed. The excretion of AsIII increased almost proportionately to the dose, while its concentration in tissues rose more than proportionately. In contrast, the excretion and tissue concentrations of methylated metabolites increased less than the dosage, or they even decreased after injection of the largest dose of AsIII. To elucidate the mechanism of the dose-dependent decrease of methylation, we quantified S-adenosylmethionine (SAME), glutathione (GSH), and adenine nucleotides in the liver of AsIII-injected rats. AsIII decreased the hepatic concentrations of GSH and adenosine 5'-triphosphate (ATP) and the energy charge in a dose-dependent manner, but increased the level of SAME. Thus, impaired methylation after AsIII overdose is not due to SAME shortage, but probably to methyltransferase inhibition. It appears that exhausted elimination capacity of AsIII, rather than MMAsIII produced from AsIII, contributes significantly to the acute toxicity of AsIII. After GSH depletion the retained AsIII can increasingly inhibit SH-enzymes, thus causing ATP depletion and energetic disorder.",
Arsenic,2279140,"Trace element concentrations and gastrointestinal parasites of Arctic terns breeding in the Canadian High Arctic Abstract: Baseline data on trace element concentrations are lacking for many species of Arctic marine birds. We measured essential and non-essential element concentrations in Arctic tern (Sterna paradisaea) liver tissue and brain tissue (mercury only) from Canada's High Arctic, and recorded the presence/absence of gastrointestinal parasites during four different phases of the breeding season. Arctic terns from northern Canada had similar trace element concentrations to other seabird species feeding at the same trophic level in the same region. Concentrations of bismuth, selenium, lead and mercury in Arctic terns were high compared to published threshold values for birds. Selenium and mercury concentrations were also higher in Arctic terns from northern Canada than bird species sampled in other Arctic areas. Selenium, mercury and arsenic concentrations varied across the time periods examined, suggesting potential regional differences in the exposure of biota to these elements. For unknown reasons, selenium concentrations were significantly higher in birds with gastrointestinal parasites as compared to those without parasites, while bismuth concentrations were higher in Arctic terns not infected with gastrointestinal parasites.",
Arsenic,1021490,"Reactive oxygen species mediate arsenic induced cell transformation and tumorigenesis through Wnt/?-catenin pathway in human colorectal adenocarcinoma DLD1 cells Abstract: Long term exposure to arsenic can increase incidence of human cancers, such as skin, lung, and colon rectum. The mechanism of arsenic induced carcinogenesis is still unclear. It is generally believed that reactive oxygen species (ROS) may play an important role in this process. In the present study, we investigate the possible linkage between ROS, ?-catenin and arsenic induced transformation and tumorigenesis in human colorectal adenocarcinoma cell line, DLD1 cells. Our results show that arsenic was able to activate p47(phox) and p67(phox), two key proteins for activation of NADPH oxidase. Arsenic was also able to generate ROS in DLD1 cells. Arsenic increased ?-catenin expression level and its promoter activity. ROS played a major role in arsenic-induced ?-catenin activation. Treatment of DLD1 cells by arsenic enhanced both transformation and tumorigenesis of these cells. The tumor volumes of arsenic treated group were much larger than those without arsenic treatment. Addition of either superoxide dismutase (SOD) or catalase reduced arsenic induced cell transformation and tumor formation. The results indicate that ROS are involved in arsenic induced cell transformation and tumor formation possible through Wnt/?-catenin pathway in human colorectal adenocarcinoma cell line DLD1 cells.",
Arsenic,627398,"Arsenic exposure and anemia in Bangladesh: A population-based study Abstract: OBJECTIVE: The purpose of this study was to examine the association between arsenic exposure and anemia, based on blood hemoglobin concentration. METHODS: Hemoglobin measures, skin lesions, arsenic exposure, and nutritional and demographic information were collected from 1954 Bangladeshi participants in the Health Effects of Arsenic Longitudinal Study. We used general linear modeling to assess the association between arsenic exposure and hemoglobin concentration, examining men and women separately. RESULTS: Arsenic exposure (urinary arsenic >200 microg/L) was negatively associated with hemoglobin among all men and among women with hemoglobin <10 d/L. Other predictors of anemia in men and women included older age, lower body mass index, and low intake of iron. Among women, the use of contraceptives predicted higher hemoglobin. CONCLUSIONS: The study suggests an association between high arsenic exposure and anemia in Bangladesh.",
Arsenic,187118,The human 32-kDa stress protein induced by exposure to arsenite and cadmium ions is heme oxygenase Abstract: Exposure of HeLa and HL60 cells to sodium arsenite or cadmium chloride led to marked increases in cellular heme oxygenase activity. SDS-polyacrylamide gel electrophoresis of [35S]methionine-labeled cellular proteins indicated that these treatments also resulted in the induction of a 32-kDa protein. Immunoblot analysis further showed that the 32-kDa protein reacted with anti-bovine heme oxygenase antibodies. Treatment of the cells with cobaltic chloride or heat induced neither the 32-kDa protein nor heme oxygenase activity. It is concluded that the 32-kDa stress protein induced by arsenite and cadmium ions in these human cells is heme oxygenase.,
Arsenic,1021983,"Low arsenite concentrations induce cell proliferation via activation of VEGF signaling in human neuroblastoma SH-SY5Y cells Abstract: Arsenic widely contaminates the environment, especially in drinking water. Although it is a known carcinogen in humans, its carcinogenic mechanism has not yet been clarified. Here, we demonstrated that a low concentration of arsenite treatment induced proliferation of human neuroblastoma SH-SY5Y cells as indicated by increases in cell viability and BrdU incorporation. Additionally, arsenite increased VEGF expression and secretion. Inhibition of VEGF-induced signaling by SU4312, the inhibitor of VEGF receptor 2 kinase, and by treatment with anti-VEGF antibody blocked arsenite-induced increases in cell proliferation. Moreover, arsenite caused activation of ERK, a key signaling molecule involved in cell proliferation, and this activation was attenuated by SU4312, suggesting that ERK activation contributes to VEGF-mediated cell proliferation induced by arsenite. Collectively, the present study reveals that a mechanism underlying arsenic-induced cell proliferation may be through induction and activation of VEGF signaling, and this may subsequently contribute to tumor formation.",
Arsenic,1579273,"Arsenic alters uptake and distribution of sulphur in Pteris vittata Abstract: Low-molecular-weight thiol (LMWT) synthesis has been reported to be directly induced by arsenic (As) in Pteris vittata, an As hyperaccumulator. Sulphur (S) is a critical component of LMWTs. Here the effect of As treatment on the uptake and distribution of S in P. vittata was investigated. In P. vittata grown under low S conditions, the presence of As in growth medium enhanced the uptake of SO4 (2-) , which was used for LMWT synthesis in fronds. In contrast, As application did not affect SO4 (2-) uptake in Nephrolepis exaltata, an As non-hyperaccumulator. Moreover, the isotope microscope system revealed that S absorbed with As accumulated locally in a vacuole-like organelle in epidermal cells, whereas S absorbed alone was distributed uniformly. These results suggest that S is involved in As transport and/or accumulation in P. vittata. X-ray absorption near-edge structure analysis revealed that the major As species in the fronds and roots of P. vittata were inorganic As(III) and As(V), respectively, and that As-LMWT complexes occurred as a minor species. Consequently, in case of As accumulation in P. vittata, S possibly acts as a temporary ligand for As in the form of LMWTs in intercellular and/or intracellular transport (e.g. vacuolar sequestration).",
Arsenic,2088506,"A phase 1 trial of intravenous 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) in patients with advanced solid tumours Abstract: <strong>BACKGROUND: </strong>4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) is a water-soluble mitochondrial toxin that binds to adenine nucleotide translocase in the inner mitochondrial membrane, thereby targeting cell proliferation. This phase 1 study investigated safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD) and pharmacokinetics (PK) of GSAO as a daily 1-h infusion for 5 days a week for 2 weeks in every three. Pharmacodynamics of GSAO was evaluated by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and circulating markers of angiogenesis.<br /><br /><strong>METHODS: </strong>Patients with advanced solid tumours received GSAO in a dose-escalation trial according to a standard '3 + 3' design that was guided by toxicity and, for the final dose escalation, by arsenic PK data.<br /><br /><strong>RESULTS: </strong>A total of 34 patients were treated with GSAO across 9 dose levels (1.3-44.0 mg/m(2)). Treatment was well tolerated with few adverse events. An additional three patients were enrolled at the 12.4 mg/m(2) dose level following a DLT of derangement of liver function tests (grade 4). At the 44.0 mg/m(2) dose level, two out of three patients had DLTs (reversible encephalopathy; paroxysmal atrial fibrillation).<br /><br /><strong>CONCLUSIONS: </strong>The MTD of GSAO was 22.0 mg/m(2)/day. There was no biomarker evidence from DCE-MRI or circulating markers of angiogenesis of an anti-vascular effect of GSAO.",
Arsenic,628348,"Does arsenic exposure increase the risk of development of peripheral vascular diseases in humans? Abstract: Arsenic has been well documented as a major risk factor in the development of blackfoot disease (BFD), a unique peripheral vascular disease (PVD) endemic to the southwestern coast of Taiwan, where residents imbibed artesian well water containing excessive amounts of arsenic for more than 50 yr. Long-term arsenic exposure was also reported to be associated with mortality attributed to PVD. A tap-water supply system was implemented in the early 1960s in the BFD endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study was to examine whether mortality attributed to PVD decreased after the consumption of artesian well water containing high concentrations of arsenic ceased and, if so, when the reduction occurred. Standardized mortality ratios (SMRs) for PVD were calculated for the BFD endemic area for the years 1971-2003. Cumulative-sum techniques were used to detect the occurrence of changes in the SMRs. Data showed that mortality due to PVD declined gradually for approximately 25 to 27 yr following cessation of consumption of this arsenic artesian well water. Based on the reversibility criterion, the association between arsenic exposure and PVD-attributed mortality is likely to be causal.",
Arsenic,711032,Role of dietary GSH in the amelioration of sodium arsenite-induced ovarian and uterine disorders Abstract: The study investigated whether dietary reduced glutathione (GSH) could be useful in alleviating arsenic-induced female gonadal injury in Wistar rats. Ingestion of sodium arsenite contaminated water (0.4 ppm) to Wistar rats for seven estrous cycles (28 days) significantly diminished ovarian key steroidogenic enzymes activities and gonadotrophins and estradiol signaling along with disrupted ovarian and uterine growth. Oxidative stress as well as histological distortion of ovarian and uterine tissue was prominent along with prolonged diestrus in arsenic-exposed rats. Decreased levels of dopamine (DA) and norepinephrine (NE) and elevated level of 5-hydroxytryptamine (5-HT) in midbrain and diencephalons were also evident following arsenic exposure. All these deleterious effects of arsenic ingestion were mitigated by administration of GSH (8.0mg/100g body weight/day). Only tissue deposition of arsenic appeared to be unaffected by dietary GSH. The study highlighted that co-administration of GSH could ameliorate arsenic-mediated injuries of female reproductive organs.,
Arsenic,2064175,"Sex-specific effects of early life cadmium exposure on DNA methylation and implications for birth weight Abstract: Dietary cadmium exposure was recently found to alter DNA methylation in adults, but data on effects early in life are lacking. Our objective was to evaluate associations between prenatal cadmium exposure, DNA methylation and birth weight. In total 127 mother-child pairs from rural Bangladesh were studied. For comparison, we included 56 children at 4.5 y. Cadmium concentrations in mothers' blood (gestational week 14) and children's urine were measured by ICPMS. Global DNA methylation was analyzed by Infinium HumanMethylation450K BeadChip in cord blood and children's blood. Maternal cadmium exposure was associated with cord blood DNA methylation (p-value &lt; 10 (-16) ). The association was markedly sex-specific. In boys, 96% of the top 500 CpG sites showed positive correlations (rS-values &gt; 0.50), whereas most associations in girls were inverse; only 29% were positive (rS &gt; 0.45). In girls we found overrepresentation of methylation changes in genes associated with organ development, morphology and mineralization of bone, whereas changes in boys were found in cell death-related genes. Several individual CpG sites that were positively associated with cadmium were inversely correlated with birth weight, although none statistically significant after correction for multiple comparisons. The associations were, however, fairly robust in multivariable-adjusted linear regression models. We identified CpG sites that were significantly associated with cadmium exposure in both newborns and 4.5-y-old children. In conclusion, cadmium exposure in early life appears to alter DNA methylation differently in girls and boys. This is consistent with previous findings of sex-specific cadmium toxicity. Cadmium-related changes in methylation were also related to lower birth weight.",
Arsenic,2345713,"Diagnostic accuracy of Xpert MTB/RIF for extrapulmonary tuberculosis specimens: establishing a laboratory testing algorithm for South Africa Abstract: South Africa implemented Xpert MTB/RIF as the initial diagnostic test for pulmonary tuberculosis (TB). Xpert MTB/RIF's accuracy for diagnosing extrapulmonary tuberculosis (EPTB) was investigated. EPTB specimens (n = 7,916) from hospitalized patients received over a 6-month period at a high-throughput TB referral laboratory in Johannesburg were investigated. Large-volume specimens were centrifuged, tissue biopsy specimens homogenized, and all specimens checked for growth of contaminating bacteria on blood agar. Contaminated samples received NALC-NaOH (N-acetyl-l-cysteine-sodium hydroxide) decontamination prior to liquid culture. Residual specimens (volumes &gt; 1 ml) after inoculation of culture (n = 1,175) were tested using the Xpert MTB/RIF sputum protocol. Using culture as the reference, Xpert MTB/RIF's overall sensitivity was 59% (95% confidence interval [95% CI], 53% to 65%) and specificity was 92% (CI, 90% to 94%), with the highest sensitivities of 91% (95% CI, 78% to 97%) for pus, 80% (95% CI, 56% to 94%) for lymph node aspirates, and 51% (95% CI, 44% to 58%) for fluids (ascitic, 59%; pleural, 47%). A difference in sensitivities was noticed between specimens classified as having a thick (87% [95% CI, 76% to 94%]) versus clear (watery) (48% [95% CI, 36% to 61%]) appearance. This was unchanged with traces of blood (52% [95% CI, 44% to 60%]) or precentrifugation (57% [95% CI, 28% to 82%]) among clear specimens. Xpert MTB/RIF generated an additional 124 specimen results that were contaminated by Mycobacterial Growth Indicator Tubes (MGIT; 10.5%) and diagnosed rifampin (RIF) resistance earlier (9.6% [25/260]). Xpert MTB/RIF's performance on EPTB specimens provides very promising results and should be considered for incorporation into national TB guidelines. Xpert MTB/RIF is less affected by contaminating bacteria and reduces laboratory labor and diagnostic delay compared to traditional methods.",
Arsenic,1337502,"Environmental justice implications of arsenic contamination: A cross-sectional, cluster-design examining exposure and compliance in community drinking water systems Abstract: BACKGROUND: Few studies of environmental justice examine inequities in drinking water contamination. Those studies that have done so usually analyze either disparities in exposure/harm or inequitable implementation of environmental policies. The US EPA's 2001 Revised Arsenic Rule, which tightened the drinking water standard for arsenic from 50 ug/L to 10 ug/L, offers an opportunity to analyze both aspects of environmental justice. METHODS: We hypothesized that Community Water Systems (CWSs) serving a higher proportion of minority residents or residents of lower socioeconomic status (SES) have higher drinking water arsenic levels and higher odds of non-compliance with the revised standard. Using water quality sampling data for arsenic and maximum contaminant level (MCL) violation data for 464 CWSs actively operating from 2005-2007 in California's San Joaquin Valley we ran bivariate tests and linear regression models. RESULTS: Higher home ownership rate was associated with lower arsenic levels (B-coefficient= -0.27 ug As/L, 95% (CI), -0.5, -0.05). This relationship was stronger in smaller systems (B-coefficient= -0.43, CI, -0.84, -0.03). CWSs with higher rates of homeownership had lower odds of receiving an MCL violation (OR, 0.33; 95% CI, 0.16, 0.67); those serving higher percentages of minorities had higher odds (OR, 2.6; 95% CI, 1.2, 5.4) of an MCL violation. CONCLUSIONS: We found that higher arsenic levels and higher odds of receiving an MCL violation were most common in CWSs serving predominantly socio-economically disadvantaged communities. Our findings suggest that communities with greater proportions of low SES residents not only face disproportionate arsenic exposures, but unequal MCL compliance challenges.",
Arsenic,2347779,"Diarrhoeal health risks attributable to water-borne-pathogens in arsenic-mitigated drinking water in West Bengal are largely independent of the microbiological quality of the supplied water Abstract: There is a growing discussion about the possibility of arsenic mitigation measures in Bengal and similar areas leading to undesirable substitution of water-borne-pathogen attributable risks pathogens for risks attributable to arsenic, in part because of uncertainties in relative pathogen concentrations in supplied and end-use water. We try to resolve this discussion, by assessing the relative contributions of water supply and end-user practices to water-borne-pathogen-attributable risks for arsenic mitigation options in a groundwater arsenic impacted area of West Bengal. Paired supplied arsenic-mitigated water and end-use drinking water samples from 102 households were collected and analyzed for arsenic and thermally tolerant coliforms [TTC], used as a proxy for microbiological water quality, We then estimated the DALYs related to key sequelae, diarrheal diseases and cancers, arising from water-borne pathogens and arsenic respectively. We found [TTC] in end-use drinking water to depend only weakly on [TTC] in source-water. End-user practices far outweighed the microbiological quality of supplied water in determining diarrheal disease burden. [TTC] in source water was calculated to contribute &lt;1% of total diarrheal disease burden. No substantial demonstrable pathogen-for-arsenic risk substitution attributable to specific arsenic mitigation of supplied waters was observed, illustrating the benefits of arsenic mitigation measures in the area studied.",
Arsenic,1031775,"Investigation of a lung cancer cluster in the melt shop of an Ontario steel producer Abstract: Workers' concerns about an excess of cancer in an electric arc steelmaking operation were investigated. In comparison with men who had worked elsewhere in the plant, an increased risk of lung cancer death was observed among men who had been employed in the melt shop. The hypothesis that the association might be related to occupational exposures is supported by the persistence of the association when the hypothesis-generating cases were removed from the analysis (p = 0.063) and by a significant trend in the risk of lung cancer with years of exposure in the melt shop. No air sampling had been performed in earlier years. Current environmental analyses in the melt shop found no polycyclic aromatic hydrocarbons (detection limit: 0.001 mg/m3), and silica levels were below 0.1 mg/m3. The carcinogenic metals arsenic and chromium were detected, but their concentrations in earlier years are unknown.",
Arsenic,627779,"Arsenic in drinking water and cerebrovascular disease, diabetes mellitus, and kidney disease in Michigan: A standardized mortality ratio analysis Abstract: BACKGROUND: Exposure to arsenic concentrations in drinking water in excess of 300 microg/L is associated with diseases of the circulatory and respiratory system, several types of cancer, and diabetes; however, little is known about the health consequences of exposure to low-to-moderate levels of arsenic (10-100 microg/L). METHODS: A standardized mortality ratio (SMR) analysis was conducted in a contiguous six county study area of southeastern Michigan to investigate the relationship between moderate arsenic levels and twenty-three selected disease outcomes. Disease outcomes included several types of cancer, diseases of the circulatory and respiratory system, diabetes mellitus, and kidney and liver diseases. Arsenic data were compiled from 9251 well water samples tested by the Michigan Department of Environmental Quality from 1983 through 2002. Michigan Resident Death Files data were amassed for 1979 through 1997 and sex-specific SMR analyses were conducted with indirect adjustment for age and race; 99% confidence intervals (CI) were reported. RESULTS: The six county study area had a population-weighted mean arsenic concentration of 11.00 microg/L and a population-weighted median of 7.58 microg/L. SMR analyses were conducted for the entire six county study area, for only Genesee County (the most populous and urban county), and for the five counties besides Genesee. Concordance of results across analyses is used to interpret the findings. Elevated mortality rates were observed for both males (M) and females (F) for all diseases of the circulatory system (M SMR, 1.11; CI, 1.09-1.13; F SMR, 1.15; CI, 1.13,-1.17), cerebrovascular diseases (M SMR, 1.19; CI, 1.14-1.25; F SMR, 1.19; CI, 1.15-1.23), diabetes mellitus (M SMR, 1.28; CI, 1.18-1.37; F SMR, 1.27; CI, 1.19-1.35), and kidney diseases (M SMR, 1.28; CI, 1.15-1.42; F SMR, 1.38; CI, 1.25-1.52). CONCLUSION: This is some of the first evidence to suggest that exposure to low-to-moderate levels of arsenic in drinking water may be associated with several of the leading causes of mortality, although further epidemiologic studies are required to confirm the results suggested by this ecologic SMR analysis.",
Arsenic,628669,"Mortality among children residing near the American Smelting and Refining Company (ASARCO) copper smelter in Ruston, Washington Abstract: A retrospective cohort study was undertaken to determine whether childhood exposure to ambient arsenic was associated with increased mortality rates. Cohort members comprised children who had lived within 4.0 km (2.5 mi) of the American Smelting and Refining Company (ASARCO) copper smelter and arsenic refinery in Ruston, Washington, for at least 2 yr during the time period from 1907 to 1932. The cohort included 1,827 boys and 1,305 girls identified from school census records. Exposure intensity was computed as the total number of years a child had lived at a residence less than 1.6 km (1.0 mi) from the smelter stack during the study period. In only one exposure intensity group (i.e., residence >/= 10.0 yr less than 1.6 km [1.0 mi] from the smelter) for boys were Cox proportional hazards ratios significantly higher than 1.00: for all causes of death (1.52), ischemic heart disease (1.77), and external causes (1.93). For girls, hazard ratios were not elevated significantly for any cause of death in any exposure intensity group.",
Arsenic,535975,"Increased levels of 8-hydroxy-2 '-deoxyguanosine attributable to carcinogenic metal exposure among schoolchildren Abstract: Arsenic, chromium, and nickel are reported in several epidemiologic studies to be associated with lung cancer. However, the health effects of arsenic, chromium, and nickel exposures are equivocal for children. Therefore, we performed a cross-sectional study to investigate possible associations between the internal concentrations of arsenic, chromium, and nickel and the level of oxidative stress to DNA in children. We measured urinary levels of arsenic, chromium, and nickel for 142 nonsmoking children using atomic absorption spectrometry. As a biomarker for oxidative stress, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were analyzed with an enzyme-linked immunosorbent assay kit. The median urinary 8-OHdG level for our subjects was 11.7 ng/mg creatinine. No obvious relationship between the levels of urinary nickel and 8-OHdG was found. Multiple linear regression analysis showed that children with higher urinary chromium had greater urinary 8-OHdG than did those with lower urinary chromium. Similarly, subjects with higher urinary arsenic had greater urinary 8-OHdG than did those with lower urinary arsenic. Furthermore, children with both high urinary arsenic and high urinary chromium had the highest 8-OHdG levels (mean SE, 16.0 +/- 1.3; VS. low arsenic/low chromium, p < 0.01) in urine, followed by those with low arsenic/high chromium (13.7 +/- 1.6; vs. low arsenic/low chromium, P = 0.25), high arsenic/low chromium (12.9 +/- 1.6 vs. low arsenic/low chromium, p = 0.52), and low arsenic/low chromium (11.5 +/- 1.3); the trend was significant (p < 0.001). Thus, environmental carcinogenic metal exposure to chromium and arsenic may play an important role in oxidative DNA damage to children.",
Arsenic,1380886,"Phenylarsine oxide and phorbol myristate acetate inhibit the CD3-induced rise of cytosolic Ca2+ in Jurkat cells by refilling internal Ca2+ stores Abstract: Phenylarsine oxide (PAO), an inhibitor of tyrosine phosphatases, has been found to inhibit the early elevation in cytosolic Ca2+ concentration ([Ca2+]i), related to the CD3 activation pathway in Jurkat T cells. This inhibition was dose-dependent, consistent with previously reported effects of PAO on tyrosine phosphatases, and reversed by dimercaptopropanol. By contrast, okadaic acid, an inhibitor of serine/threonine phosphatases, had no effect on CD3-induced Ca2+ flux. PAO was compared with phorbol 12-myristate 13-acetate (PMA), which caused a similar, although less potent, inhibition as previously described. The two reagents produced additive inhibition of the CD3-induced [Ca2+]i rise, but did not affect thapsigargin- or ionomycin-driven Ca2+ flux in Jurkat cells. PAO and PMA prevented cells from complete depletion of intracellular Ca2+ stores by an anti-CD3 monoclonal antibody (mAb) and restored, at least partially, the ionomycin-sensitive pool, when added after anti-CD3 mAb. Moreover, the CD3-induced inhibition of phosphatidylserine synthesis, due to depletion of internal Ca2+ stores, is reversed by PAO and PMA. Anti-phosphotyrosine immunoblot analysis show that these effects cannot be accounted for by an inhibition of CD3-induced tyrosine phosphorylations. We propose that PAO and, to a lesser extent, PMA allow the refilling of internal compartments by Ca2+, which consequently abrogates a capacitative entry of external Ca2+.",
Arsenic,1677597,"Pond-derived organic carbon driving changes in arsenic hazard found in asian groundwaters Abstract: Microbially mediated reductive processes involving the oxidation of labile organic carbon are widely considered to be critical to the release of arsenic into shallow groundwaters in South and Southeast Asia. In areas where there is significant pumping of groundwater for irrigation the involvement of surface-derived organic carbon drawn down from ponds into the underlying aquifers has been proposed but remains highly controversial. Here we present isotopic data from two sites with contrasting groundwater pumping histories that unequivocally demonstrate the ingress of surface pond-derived organic carbon into arsenic-containing groundwaters. We show that pond-derived organic carbon is transported to depths of up to 50 m even in an arsenic-contaminated aquifer in Cambodia thought to be minimally disturbed by groundwater pumping. In contrast, in the extensively exploited groundwaters of West Bengal, we show that pond-derived organic carbon is transported in shallow groundwater to greater depths, in excess of 100 m in the aquifer. Intensive pumping of groundwaters may potentially drive secular increases in the groundwater arsenic hazard in this region by increasing the contribution of bioavailable pond-derived dissolved organic carbon drawn into these aquifer systems and transporting it to greater depths than would operate under natural flow conditions.",
Arsenic,627795,"DNA–protein cross-links and sister chromatid exchanges induced by dimethylarsinic acid in human fibroblasts cells Abstract: Biotransformation of inorganic arsenic to form both methylarsinic acid (MA) and dimethylarsinic acid (DMA) has traditionally been considered as a mechanism to facilitate the detoxification and excretion of arsenic. However, the methylation of inorganic arsenic as a detoxification mechanism has been questioned due to recent studies revealing an important role of organic arsenic in the induction of genetic damage. In a previous report a reduction of DNA migration after treatment of cells with DMA was described. In order to further evaluate the possible induction of protein–DNA adducts, an experiment was performed taking into account other parameters and modifications of the standard alkaline comet assay. In addition, the results obtained with the comet assay were compared with those obtained by analyzing the induction of sister chromatid exchanges (SCEs). SCE frequencies were significantly increased in treated cells in relation to controls (p < 0.001). Furthermore, in the standard alkaline comet assay, as well as in the control assay for proteinase K treatment, a significant dose-dependent reduction in tail moment was observed. Nevertheless, the post-treatment with proteinase K induced the release of proteins joined to the DNA and consequently, a dose-dependent increment in DNA migration was observed (p < 0.001). These results suggest that DNA–protein cross-links may be an important genotoxic effect induced by dimethylarsinic acid in human MRC-5 cells.",
Arsenic,1337519,"Placental concentrations of heavy metals in a mother-child cohort Abstract: Heavy metals are environmental contaminants with properties known to be toxic for wildlife and humans. Despite strong concerns about their harmful effects, little information is available on intrauterine exposure in humans. The aim of this study was to evaluate prenatal exposure to As, Cd, Cr, Hg, Mn, and Pb and its association with maternal factors in a population-based mother-child cohort in Southern Spain. Between 2000 and 2002, 700 pregnant women were recruited and 137 placentas from the cohort were randomly selected and analyzed for the selected metals by atomic absorption. Maternal sociodemographic and lifestyle factors were obtained by questionnaire after delivery. Bivariate analysis and multivariate linear regression were performed. Cd and Mn concentrations were detected in all placentas, while Cr, Pb, and Hg were found in 98.5%, 35.0%, and 30.7% of samples, respectively. The highest concentrations were observed for Pb (mean: 94.80ng/g wet weight of placenta), followed by Mn (63.80ng/g), Cr (63.70ng/g), Cd (3.45ng/g), and Hg (0.024ng/g). Arsenic was not detected in any sample. Gestational age and smoking during pregnancy were associated with placental Cd concentrations, while no factor appeared to influence concentrations of Cr, Hg, Mn, or Pb. In comparison to results of European studies, these concentrations are in a low-intermediate position. Studies are required to investigate the factors contributing to early exposure to heavy metals and to determine how placental transfer of these toxic compounds may affect children's health.",
Arsenic,732023,"Influence of thyroxine and n-propylthiouracil on nephro-toxicity of inorganic arsenic in rat Abstract: The effect of hyper or hypoactive thyroid on the renal toxicity of arsenic trioxide has been studied in rats. It was observed that pre-treatment of rats with thyroxine stimulates arsenic excretion in urine. The anti-thyroid drug n-propylthiouracil (PTU), inhibits the accumulation of arsenic in renal tissue. Both treatments affect the renal pathology. Histopathological lesions are less severe in PTU and arsenic-treated rats in comparison to thyroxine and arsenic-treated rats. Ultrastructural studies support light microscopical observations. An adaptive response was noticed against arsenic in PTU pre-treated rats. We attribute this response to decreased glutathione-S-transferase (GSH) activity and increased GSH synthesis in the kidney. A relationship between thyroidal activity and arsenic toxicity is suggested by present observations.",
Arsenic,2279507,"In situ treatment of arsenic-contaminated groundwater by air sparging Abstract: Arsenic contamination of groundwater is a major problem in some areas of the world, particularly in West Bengal (India) and Bangladesh where it is caused by reducing conditions in the aquifer. In situ treatment, if it can be proven as operationally feasible, has the potential to capture some advantages over other treatment methods by being fairly simple, not using chemicals, and not necessitating disposal of arsenic-rich wastes. In this study, the potential for in situ treatment by injection of compressed air directly into the aquifer (i.e. air sparging) is assessed. An experimental apparatus was constructed to simulate conditions of arsenic-rich groundwater under anaerobic conditions, and in situ treatment by air sparging was employed. Arsenic (up to 200 ?g/L) was removed to a maximum of 79% (at a local point in the apparatus) using a solution with dissolved iron and arsenic only. A static jar test revealed arsenic removal by co-precipitation with iron at a molar ratio of approximately 2 (iron/arsenic). This is encouraging since groundwater with relatively high amounts of dissolved iron (as compared to arsenic) therefore has a large theoretical treatment capacity for arsenic. Iron oxidation was significantly retarded at pH values below neutral. In terms of operation, analysis of experimental results shows that periodic air sparging may be feasible.",
Arsenic,2347667,"Some selected heavy metal concentrations in water, sediment, and oysters in the Er-Ren estuary, Taiwan: Chemical fractions and the implications for biomonitoring Abstract: Studies of heavy metal contamination and ecological risk in estuaries are an important emerging area of environmental science. However, there have been few detailed studies of heavy metal contamination that concern the spatial variation of heavy metal levels in water, sediment, and oyster tissue. Because of the effective uptake of heavy metals, cultured oysters are a cheap and effective subject for study. This study, conducts an experiment in the Er-Ren river to examine the biological uptake of heavy metals in farmed, cultured oysters. The distribution of copper, zinc, lead, cadmium, and arsenic concentrations in water, sediment, and oysters from the Er-Ren river is also evaluated. By sequential extraction of the sediments, the following order of mobilities is found for heavy metals Pb?>?Cd?>?As?>?Zn?>?Cu. The highest percentages of heavy metals are found in the residual phase. The mean uptake rates for young oysters are 7.24 mg kg(-1) day(-1) for Cu and 94.52 mg kg(-1) day(-1) for Zn, but that for adult oyster is 10.79 mg kg(-1) day(-1) for Cu and 137.24 mg kg(-1) day(-1) for Zn. With good policies and management, the establishment of cultured oyster frames in these contaminated tributaries and near shore environments is a potential method for removing Cu and Zn and protecting the coast.",
Arsenic,710927,"Free fatty acids profile of the fetal brain and the plasma, liver, brain and kidneys of pregnant rats treated with sodium arsenite at mid-organogenesis Abstract: Free fatty acids (FFAs) are known to be markers of cellular membrane degradation through lipid peroxidation and are substrates for the production of reactive oxygen species (ROS). Oxidative stress, due to overproduction of ROS, may facilitate cellular insult by various toxicants. The ability of the rat conceptus to respond to toxic stress may be critical for normal development. In this study, the effects of the environmental toxicant sodium arsenite (NaAsO?) on FFAs were investigated after administering a single oral dose, in water and in a lipid medium, to pregnant rats on gestational day (GD) 10, a time point at mid-organogenesis. NaAsO? was administered in deionized water (AsH?O) or in half and half dairy cream (AsHH) at a dose of 41 mg sodium arsenite (NaAsO?)/kg body weight. Control animals were treated with either dairy cream (HH) or deionized water (H?O). The animals were sacrificed on GD 20. The fetal brain and the maternal liver, brain, plasma and kidneys were harvested. The FFAs were extracted and analyzed by gas chromatography. In the liver, there was an increase of myristic acid (1200%), myristoleic acid (174%), palmitic acid (47%), elaidic acid (456%), oleic acid (165%) and docosahexaenoic acid (224%) in the AsH?O group as compared to the AsHH group. Oleic acid and arachidonic acid were increased by 192% and 900%, respectively, in the AsH?O group as compared to the H?O group, and myristic acid was decreased by 90% in the AsHH group as compared to the HH group. In the maternal brain, myristoleic acid was decreased by 91% in the AsH?O group as compared to the H?O group, and DHA increased by 148% in the AsHH group as compared to the HH group. In the fetal brain, myristic and stearic acids were decreased by 87% and 89%, respectively, in the AsH?O group as compared to the AsHH group. Myristic, stearic and arachidonic acids were increased by 411%, 265%, and 144%, respectively, in the AsHH group as compared to the HH group. There was no effect on the fatty acids concentrations in the kidney or plasma as compared to controls. This study shows that NaAsO? produced a differential effect on the fatty acid profiles in rats. Further investigation is needed to elucidate the role of fatty acids in differential signaling and regulation by either the palmitoylation or myristoylation process of cellular functions in these target organs.",
Arsenic,2278446,"Two rice plasma membrane intrinsic proteins, OsPIP2;4 and OsPIP2;7, are involved in transport and providing tolerance to boron toxicity Abstract: Boron (B) toxicity is responsible for low cereal crop production in a number of regions worldwide. In this report, we characterized two rice genes, OsPIP2;4 and OsPIP2;7, for their involvement in B permeability and tolerance. Transcript analysis demonstrated that the expression of OsPIP2;4 and OsPIP2;7 were downregulated in shoots and strongly upregulated in rice roots by high B treatment. Expression of both OsPIP2;4 and OsPIP2;7 in yeast HD9 strain lacking Fps1, ACR3, and Ycf1 resulted in an increased B sensitivity. Furthermore, yeast HD9 strain expressing OsPIP2;4 and OsPIP2;7 accumulated significantly higher B as compared to empty vector control, which suggests their involvement in B transport. Overexpression of OsPIP2;4 and OsPIP2;7 in Arabidopsis imparted higher tolerance under B toxicity. Arabidopsis lines overexpressing OsPIP2;4 and OsPIP2;7 showed significantly higher biomass production and greater root length, however there was no difference in B accumulation in long term uptake assay. Short-term uptake assay using tracer B (B-10) in shoots and roots demonstrated increased B-10 accumulation in Arabidopsis lines expressing OsPIP2;4 and OsPIP2;7, compare to wild type control plants. Efflux assay of B in the roots showed that B-10 was effluxed from the Arabidopsis transgenic plants overexpressing OsPIP2;4 or OsPIP2;7 during the initial 1-h of assay. These data indicate that OsPIP2;4 and OsPIP2;7 are involved in mediating B transport in rice and provide tolerance via efflux of excess B from roots and shoot tissues. These genes will be highly useful in developing B tolerant crops for enhanced yield in the areas affected by high B toxicity.",
Arsenic,1248924,"Occurrence and levels of organochlorine compounds in human breast milk in Bangladesh Abstract: In low-income countries, the use of some organochlorine pesticides is still common in order to increase food production. Monitoring the chemical exposure is an important step in risk-reducing strategies. This is the first study to report concentrations of organochlorines in breast milk of women from Bangladesh where farming is the main income source. Organochlorines such as p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD (i.e., ?DDT), HCB, ?-, ?- and ?-HCH, trans-chlordane, cis-chlordane, oxy-chlordane, trans-nonachlor, cis-nonachlor, mirex and polychlorinated biphenyls (CB 28, 52, 99, 101, 105, 114, 118, 123, 128, 138, 141, 149, 153, 156, 157, 163, 167, 170, 180, 183, 187, 189, 194) were analyzed in breast milk collected in 2002 from 72 first-time mothers (median age 20years) living in the rural area Matlab, Bangladesh. While the concentrations of PCBs and many of the pesticides were low, the concentrations of p,p'-DDT and its metabolite p,p'-DDE were high (median 349 and 1645ngg(-1)lipid, respectively) in comparison to other countries. The median value of ?DDT was 2123ngg(-1)lipid. The estimated daily exposure to p,p'-DDT, p,p'-DDE and ?DDTs was 10, 30 and 42?gkg(-1) body weight, respectively, in 3months old infants. The p,p'-DDE/p,p'-DDT ratio ranged from 1 to 23, where 58% of the mothers had a ratio below 5 indicating recent or ongoing DDT exposure. This study reports infant exposure and maternal body burden of organochlorines through breast milk. Although the findings give no reason to limit breast-feeding, it is essential to identify the main exposure sources and find means to decrease the exposure.",
Arsenic,1070435,"Arsenic and antimony transporters in eukaryotes Abstract: Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters.",
Arsenic,688016,"Differential effects of toxic metal compounds on the activities of Fpg and XPA, two zinc finger proteins involved in DNA repair Abstract: Even though not mutagenic, compounds of the carcinogenic metals nickel, cadmium, cobalt and arsenic have been shown previously to inhibit nucleotide excision repair and base excision repair at low, non-cytotoxic concentrations. Since some toxic metals have high affinities for -SH groups, we used the bacterial formamidopyrimidine-DNA glycosylase (Fpg protein) and the mammalian XPA protein as models to investigate whether zinc finger structures in DNA repair enzymes are particularly sensitive to carcinogenic and/or toxic metal compounds. Concentrations of < / =1 mM Ni(II), Pb(II), As(III) or Co(II) did not affect the activity of the Fpg protein significantly. In contrast, the enzyme was inhibited in a dose-dependent manner by Cd(II), Cu(II) or Hg(II), starting at concentrations of 50 microM, 5 microM and 50 nM, respectively. Simultaneous treatment with Cd(II) or Cu(II) and Zn(II) partly prevented the inhibitions, while no reversal of inhibition was observed when Zn(II) was added after Cd(II) or Cu(II). In the case of Hg(II), Zn(II) had no protective effect independent of the time of its addition; however, the enzyme activity was completely restored by glutathione. Regarding XPA, Hg(II), Pb(II) or As(III) did not diminish its binding to an UV-irradiated oligonucleotide, while Cd(II), Co(II), Cu(II) and Ni(II) reduced its DNA-binding ability. Simultaneous treatment with Zn(II) prevented largely the inhibition induced by Cd(II), Co(II), and Ni(II), but only slightly in the case of Cu(II). Collectively, the results indicate that both proteins were inhibited by Cd(II) and Cu(II), XPA was additionally inactivated by Ni(II) and Co(II), and Fpg but not XPA was strongly affected by Hg(II). Even though other mechanisms of protein inactivation cannot be completely excluded, zinc finger structures may be sensitive targets for toxic metal compounds, but each zinc finger protein has unique sensitivities.",
Arsenic,1255533,"Mercury and arsenic in green tiger shrimp from the Persian Gulf Abstract: Mercury and arsenic pollution has been recognized as a potential environmental and public health problem for over 40 years. The major source of exposure to mercury and arsenic for humans is the ingestion of sea food. Concentrations of mercury and arsenic in the muscle samples of green tiger shrimp (Penaeus semisulcatus) from the Persian Gulf were determined by cold vapor atomic absorption spectrometry. Concentrations of metals in muscle samples were 49-115 µg kg(-1) for mercury, 115-131 µg kg(-1)for arsenic, with means of 82.7 and 251.6 µg kg(-1), respectively. Statistical analysis showed no significant difference of mercury and arsenic concentration in shrimp muscles between selected stations (Bushehr, Khuzestan, and Hormozgan provinces). No significant difference was found among heavy metal contents of male and female shrimps. The results of this study indicate that the green tiger shrimp from the Persian Gulf have concentrations well below the maximum permissible levels for mercury (500 µg kg(-1)) and arsenic (6000 µg kg(-1)), according to international standards, with no health risk of consumers.",
Arsenic,627574,"RIP kinase is involved in arsenic-induced apoptosis in multiple myeloma cells Abstract: These studies explore the molecular effect of arsenicals on MM cells. Freshly isolated cells derived from patients with advanced, chemo-refractory myeloma as well as human myeloma cell lines, ARP-1, RPMI-8226 and H929 were exposed to the organic arsenical melarsoprol and to the inorganic compound AT. Both agents potently induced apoptosis in myeloma cells. Exposure to 1-5 microM AT or melarsoprol for 6 hours suppressed NF-kappa B DNA binding and enhanced of c-Jun kinase (JNK) activity. Arsenic also activated caspase-3 resulting in the cleavage of poly (ADP-ribose) polymerase (PARP) and Fas/TNF alpha related receptor interacting protein (RIP). In contrast to reported observations in acute promyelocytic leukemia, myeloma cell apoptosis was not associated with either the downregulation of Bcl-2 protein or with alterations in the expression of other Bcl-2 family members, Bax, Bak, Bag, and Bcl-xl. This study first shows that arsenic induces apoptotic signaling in MM through the cleavage of TNF alpha related receptor interacting protein (RIP). RIP is a key downstream protein in FasL/ TNF alpha /TRAIL induced apoptosis and a major antiapoptotic adaptor of pathways through NF-kappa B and JNK. RIP has not been previously characterized in myeloma. This study supports the hypothesis that arsenicals share common mediators (RIP, NF-kappa B, PARP, caspase-3) with death receptor induced apoptosis. These studies provide an important insight into the molecular mechanism of AT induced apoptosis and can be used in the development of adjuvant therapy for MM, presently an incurable disease.",
Arsenic,627436,"Specific induction of oxidative stress in terminal bronchiolar Clara cells during dimethylarsenic-induced lung tumor promoting process in mice Abstract: The induction of oxidative stress in pulmonary cells during the process of lung tumor promotion by dimethylarsinic acid (DMA), a main metabolite of inorganic arsenics in mammals, was examined by immunohistochemical analysis using a specific antibody against 4-hydroxy-2-nonenal (4HNE) adducts, which are major aldehydic metabolites of lipid peroxidation. We demonstrated that 4HNE-modified proteins existed specifically in the secretory granules in terminal bronchiolar Clara cells. Furthermore, the degree of positive staining increased with the duration of DMA administration. Transmission electron microscopy revealed morphological changes in the Clara cells of DMA-treated mice. These results suggest that Clara cells are the major target cell for DMA-induced oxidative stress and that the cells may play an important role in the lung tumor promotion process in mice.",
Arsenic,1027377,"Prevalence of arsenicosis in terai, Nepal Abstract: This paper summarizes the findings of surveys on arsenicosis cases conducted during 2001-2004 in terai, Nepal, by governmental and non-governmental organizations in their respective project areas and by some national and international institutes. Studies were conducted in six arsenic-contaminated districts of terai, namely Nawalparasi, Bara, Parsa, Rautahat, Rupandehi, and Kapilvastu. In these districts, arsenic contamination in tubewells varied from 2.1% to 25.7%. The prevalence of arsenicosis was, on average, 2.2% and varied from 0.7% in Kapilavastu district to 3.6% in Nawalparasi district. In the community-based study, the highest prevalence (18.6%) of arsenicosis was found in Patkhouli village of Nawalparasi, where 95.8% of tubewells were contaminated with arsenic. The prevalence of arsenicosis was higher in older age-groups (>50 years) of both the sexes. Males suffered more from arsenicosis than females (odds ratio: 2.50, 95% confidence interval 1.80-3.47). Skin manifestations, such as melanosis and keratosis, were the common symptoms of arsenicosis. Most patients were identified in the early or mild stage of the disease. They are expected to recover if further exposure to arsenic could be avoided by providing arsenic-safe drinking-water through intervention measures.",
Arsenic,62192,"Mortality pattern in a glass producing area in SE Sweden Abstract: Because of discharges, mainly of lead, from glassworks in an otherwise rural and unpolluted area in southeast Sweden the population became concerned about the potential risks of cancer and an epidemiological study was requested. The total and the specific cancer mortality in the three parishes around the glassworks were found to be approximately normal, both by comparison with national death rates and the death rates of another, similarly rural, area. More interesting results, however, were obtained in several case-referent studies also undertaken to study mortality from specific cancer sites and cardiovascular disease with regard to employment in the glassworks. A significant excess of deaths from stomach cancer, especially in glassblowers, lung cancer, and cardiovascular disease was observed among the glassworkers. Occupational exposures in the glassworks, especially to arsenic, may be of aetiological importance.",
Arsenic,2088563,"Sodium meta-arsenite induces reactive oxygen species-dependent apoptosis, necrosis, and autophagy in both androgen-sensitive and androgen-insensitive prostate cancer cells Abstract: Sodium meta-arsenite (NaAsO2), a novel compound synthesized by Komipham International Co. Ltd, is an orally bioavailable, water-soluble trivalent arsenical that has shown potent cytotoxic activity in human solid cancer cells in vitro and in vivo, and is currently undergoing phase I/II clinical trials for the treatment of prostate cancer. In this study, mechanisms of cell death induced by sodium meta-arsenite were investigated. Sodium meta-arsenite reduced cell viability and increased the sub-G1 population in cell cycle analysis in both androgen-sensitive LNCaP and androgen-insensitive CWR22RV1 cells. The apoptosis induced by sodium meta-arsenite was associated with cleavage of caspases 3, 8, and 9, and poly (ADP-ribose) polymerase (PARP) and increased annexin V-positive cells, and was inhibited by the pan-caspase inhibitor Z-VAD-fmk. Sodium meta-arsenite also increased the level of the autophagy marker microtubule-associated protein 1 light chain 3 (LC3)-II and the number of autophagic vacuoles as shown by electron microscopy. Both the autophagy inhibitor 3-methyladenine and the necrosis inhibitor necrostatin-1 blocked cell death induced by sodium meta-arsenite. Moreover, sodium meta-arsenite led to the accumulation of intracellular reactive oxygen species (ROS) and N-acetyl-L-cysteine (NAC), a ROS scavenger, decreased sodium meta-arsenite-induced levels of cleaved PARP and LC3-II. Propidium iodide (PI) staining also showed that NAC restored membrane integrity, damaged by sodium meta-arsenite. Therefore, these results suggest that sodium meta-arsenite induces apoptotic, necrotic, and autophagic cell death through intracellular ROS accumulation in both androgen-sensitive and androgen-insensitive prostate cancer cells and may be used as a new anticancer drug for the treatment of prostate cancer.",
Arsenic,1015887,"Variation of As concentration between soil types and rice genotypes and the selection of cultivars for reducing As in the diet Abstract: Human exposure to toxic heavy metals via the food chain is of increasing concern. In the present study, the effects of soil type and genotype on variation in arsenic (As) concentrations of different organs were investigated by using nine rice cultivars grown in two soils, with two levels of As contamination. There were significant genotypic differences (P&lt;0.05) in As concentrations of all organs, and As concentrations of polished grain were significantly affected by genotype and soil type. The As concentration in polished grain was higher in red paddy soil under As treatment, with range from 0.24 to 1.03mgkg(-1), and the As concentration of three cultivars exceeded the concentration of Chinese Food Hygiene Standard (0.7mgkg(-1)). The As concentrations in stems, leaves and polished grain were all significantly and positively correlated. The As concentrations in polished grain were positively and significantly (P&lt;0.01) correlated with As root-grain translocation factor. The results indicated that As concentration in grain was partially governed by As uptake and the transfer of As from root to grain. The grain As concentration of the nine cultivars was significantly correlated between the two soil types at different levels of As contamination. Some genotypes, such as japonica rice (e.g. Ning jing 1 and Nan jing 32) had consistently low grain As concentrations. The results suggest the possibility of breeding the As rice cultivars to produce grain for safe consumption from soils with slight and moderate levels of As.",
Arsenic,1453800,"Urinary arsenic profiles and the risks of cancer mortality: A population-based 20-year follow-up study in arseniasis-endemic areas in Taiwan Abstract: Few studies investigated the association between chronic arsenic exposure and the mortality of cancers by estimating individual urinary arsenic methylation profiles. Therefore, we compared with the general population in Taiwan to calculate the standardized mortality ratio (SMR) in arseniasis-endemic area of Taiwan from 1996 to 2010 and evaluated the dose-response relationships between environmental arsenic exposure indices or urinary arsenic profiles and the mortality of cause-specific cancer. A cohort of 1563 residents was conducted and collected their urine sample and information regarding arsenic exposure from a questionnaire. All-cause death was identified using the National Death Registry of Taiwan. Urinary arsenic profiles were measured using high performance liquid chromatography-hydride generator-atomic absorption spectrometry. We used Cox proportional hazard models to evaluate the mortality risks. In results, 193 all-site cancer deaths, and 29, 71, 43 deaths respectively for liver, lung and bladder cancers were ascertained. The SMRs were significantly high in arseniasis-endemic areas for liver, lung, and bladder cancers. People with high urinary InAs% or low DMA% or low secondary methylation index (SMI) were the most likely to suffer bladder cancer after adjusting other risk factors. Even stopping exposure to arsenic from the artesian well water, the mortality rates of the residents were higher than general population. Finally, urinary InAs%, DMA% and SMI could be the potential biomarkers to predict the mortality risk of bladder cancer.",
Arsenic,1021979,"Arsenic (As) Inhibits Radicle Emergence and Elongation in Phaseolus aureus by Altering Starch-Metabolizing Enzymes Vis-à-Vis Disruption of Oxidative Metabolism Abstract: The present study investigated the effect of Arsenic (As; 5, 10, 50 ?M) on protein and sugar metabolism vis-à-vis oxidative damage during early germination process and radicle emergence (at 12, 24 and 48 h stage) in Phaseolus aureus. As-exposure (50 ?M) significantly enhanced protein content (by 40-60%), whereas carbohydrate content declined (by 31-44%) over that in the control. It was associated with a decline in the activities of proteases (47-53%), and increase in the activities of ?- and ?-amylases, starch phosphorylases, and acid invertases by 3.0, 2.6, 4.8, and 1.7 times after 48 h exposure to 50 ?M As. The alteration in protein and carbohydrate metabolic machinery was also accompanied by As-induced reactive oxygen species (ROS)-mediated oxidative damage. As treatment enhanced malondialdehyde and hydrogen peroxide content by 46-252% and 23-216%, and hydroxyl and superoxide ion generation by 15-104% and 17-278%, respectively. As-induced lipid peroxidation and membrane disruption was confirmed by enhanced electrolyte leakage (by 49%) and reduced cell viability (by 43%). Furthermore, in response to 50 ?M As, the activities of superoxide dismutases, catalases, ascorbate peroxidases, guaiacol peroxidases, and glutathione reductases increased by 77%, 70%, 116%, 43% and 120%, respectively, in radicles at 48 h stage over that in the control. The study concludes that As inhibits radicle emergence and elongation in germinating P. aureus seeds by altering biochemical processes related to sugar metabolism and inducing an ROS-mediated oxidative damage.",
Arsenic,1327714,"Complexes containing activating transcription factor (ATF)/cAMP-responsive-element-binding protein (CREB) interact with the CCAAT/enhancer-binding protein (C/EBP)?ATF composite site to regulate Gadd153 expression during the stress response Abstract: Gadd153, also known as chop, encodes a member of the CCAAT/enhancer-binding protein (C/EBP) transcription factor family and is transcriptionally activated by cellular stress signals. We recently demonstrated that arsenite treatment of rat pheochromocytoma PC12 cells results in the biphasic induction of Gadd153 mRNA expression, controlled in part through binding of C/EBPbeta and two uncharacterized protein complexes to the C/EBP-ATF (activating transcription factor) composite site in the Gadd153 promoter. In this report, we identified components of these additional complexes as two ATF/CREB (cAMP-responsive-element-binding protein) transcription factors having differential binding activities dependent upon the time of arsenite exposure. During arsenite treatment of PC12 cells, we observed enhanced binding of ATF4 to the C/EBP-ATF site at 2 h as Gadd153 mRNA levels increased, and enhanced binding of ATF3 complexes at 6 h as Gadd153 expression declined. We further demonstrated that ATF4 activates, while ATF3 represses, Gadd153 promoter activity through the C/EBP-ATF site. ATF3 also repressed ATF4-mediated transactivation and arsenite-induced activation of the Gadd153 promoter. Our results suggest that numerous members of the ATF/CREB family are involved in the cellular stress response, and that regulation of stress-induced biphasic Gadd153 expression in PC12 cells involves the ordered, sequential binding of multiple transcription factor complexes to the C/EBP-ATF composite site.",
Arsenic,69174,"Ingested inorganic arsenic and prevalence of diabetes mellitus Abstract: To examine the association between ingested inorganic arsenic and prevalence of diabetes mellitus, in 1988, the authors studied 891 adults residing in villages in southern Taiwan where arseniasis is hyperendemic. The status of diabetes mellitus was determined by an oral glucose tolerance test and a history of diabetes regularly treated with sulfonylurea or insulin. The cumulative arsenic exposure in parts per million-years was calculated from the detailed history of residential addresses and duration of drinking artesian well water obtained through standardized interviews based on a structured questionnaire and the arsenic concentration in well water. The body mass index was derived from body height and weight measured according to a standard protocol, while the physical activity at work was also obtained by questionnaire interviews. Residents in villages where the chronic arseniasis was hyperendemic had a twofold increase in age-and sex-adjusted prevalence of diabetes mellitus compared with residents in Taipei City and the Taiwan area. There was a dose-response relation between cumulative arsenic exposure and prevalence of diabetes mellitus. The relation remained significant after adjustment for age, sex, body mass index, and activity level at work by a multiple logistic regression analysis giving a multivariate-adjusted odds ratio of 6.61 and 10.05, respectively, for those who had a cumulative arsenic exposure of 0.1–15.0 and greater than 15.0 ppm-year compared with those who were unexposed. These results suggest the chronic arsenic exposure may induce diabetes mellitus in humans.",
Arsenic,1352972,"PPARgamma is a key target of butyrate-induced caspase-3 activation in the colorectal cancer cell line Caco-2 Abstract: <strong>BACKGROUND: </strong>Butyrate, a potent histone deacetylase inhibitor, belongs to a promising new class of antineoplastic agents with the capacity to induce apoptosis of cancer cells. However, the underlying mechanisms of action have yet not been elucidated.<br /><br /><strong>AIM: </strong>To further investigate the molecular events involved in butyrate-induced caspase-3 activation in Caco-2 wild-type, empty-vector and dominant-negative PPARgamma mutant cells along the signalling pathway. In this context, the involvement and up-regulation of PPARgamma was examined.<br /><br /><strong>RESULTS: </strong>Stimulation of cells with butyrate resulted in increased expression of PPARgamma mRNA, protein, and activity as well as phospho-p38 MAPK protein expression and caspase-3 activity. Arsenite, a direct stimulator of p38 MAPK, also led to an increased PPARgamma expression, thereby mimicking the effects of butyrate. In contrast, butyrate-mediated up-regulation of PPARgamma was counteracted by co-incubation with the p38 MAPK inhibitor SB203580. Treatment of cells with butyrate resulted in both increased caspase-8 and -9 activity and reduced expression of XIAP and survivin. However, butyrate-mediated effects on these apoptosis-regulatory proteins leading to caspase-3 activation were almost completely abolished in Caco-2 dominant-negative PPARgamma mutant cells.<br /><br /><strong>CONCLUSIONS: </strong>Our data clearly unveil PPARgamma as a key target in the butyrate-induced signalling cascade leading to apoptosis via caspase-3 in Caco-2 cells.",
Arsenic,628652,"Evaluation of biochemical changes in chronic arsenic poisoning among Bangladeshi patients Abstract: An estimated 40 million people in Bangladesh have been suffering from arsenic toxicity-related diseases because of drinking water contamination with high levels of naturally occurring arsenic. To evaluate the biochemical changes in chronic arsenic exposure, a total of 115 exposed subjects diagnosed as arsenicosis patients were examined and interviewed, and 120 unexposed volunteers were enrolled in this study. Drinking water, urine and peripheral blood samples were collected from all participants and analyzed. The average levels of arsenic in the drinking water and spot urine samples of the arsenicosis patients were 218.1 microg/L and 234.6 microg/L, respectively, and duration of exposure was 7.6 +/- 5.2 yrs that ranged from 1-25 yrs. Prevalence of diabetes mellitus among chronic arsenic-exposed subjects was about 2.8 times higher than the unexposed subjects. The activities of alkaline phosphatase were significantly elevated in the patients, 197 U/L compared to 149 U/L in the controls, but alanine transaminase and aspartate transaminase were mostly normal. The patients had significantly lower levels of serum creatinine, 0.97 mg/dL compared to 1.15 mg/dL in the controls; but had significantly elevated levels of total protein, 84 g/L and 77 g/L respectively. The mean level of inorganic phosphate in the serum of arsenicosis patients was 6.4 mg/dL compared to 4.6 mg/dL in the unexposed subjects and the level was significantly higher, indicating substitution of the pentavalent arsenate for the phosphate ion causing underutilization of the latter. Evaluation of the lipid profiles showed while the levels of triacylglycerol were not much different, the patients had significantly lower levels of cholesterol, HDL-cholesterol and LDL-cholesterol compared to the unexposed subjects. These findings suggest significant changes in biochemical parameters in human arsenic toxicity.",
Arsenic,2278660,"Phytoremediation of lead (Pb) and arsenic (As) by Melastoma malabathricum L. From contaminated soil in separate exposure Abstract: This study was conducted to investigate the uptake of lead (Pb) and arsenic (As) from contaminated soil using Melastoma malabathricum L. species. The cultivated plants were exposed to As and Pb in separate soils for an observation period of 70 days. From the results of the analysis, M. malabathricum accumulated relatively high range of As concentration in its roots, up to a maximum of 2800 mg/kg. The highest accumulation of As in stems and leaves was 570 mg/kg of plant. For Pb treatment, the highest concentration (13,800 mg/kg) was accumulated in the roots of plants. The maximum accumulation in stems was 880 mg/kg while maximum accumulation in leaves was 2,200 mg/kg. Only small amounts of Pb were translocated from roots to above ground plant parts (TF < 1). However, a wider range of TF values (0.01–23) for As treated plants proved that the translocation of As from root to above ground parts was greater. However, the high capacity of roots to take up Pb and As (BF > 1) is indicative this plants is a good bioaccumulator for these metals. Therefore, phytostabilisation is the mechanism at work in M. malabathricum's uptake of Pb, while phytoextraction is the dominant mechanism with As.",
Arsenic,1250990,"Raman and IR spectroscopic investigation of As adsorbed on Mn(3)O(4) magnetic composites Abstract: Raman and IR spectra were recorded of the As-loaded Mn(3)O(4) magnetic composites obtained from the adsorption studies performed with As(III). XANES results for the composite after As(III) removal tests show that the As adsorbed is at the oxidized arsenic form, As(V). Monodentate and bidentate surface complexes are suggested for arsenic adsorption onto the composite (5-16mg/g). Precipitation of manganese arsenate is observed for high As loading (35mg/g).",
Arsenic,1579370,"The Contribution of ArsB to Arsenic Resistance in Campylobacter jejuni Abstract: Arsenic, a toxic metalloid, exists in the natural environment and its organic form is approved for use as a feed additive for animal production. As a major foodborne pathogen of animal origin, Campylobacter is exposed to arsenic selection pressure in the food animal production environments. Previous studies showed that Campylobacter isolates from poultry were highly resistant to arsenic compounds and a 4-gene operon (containing arsP, arsR, arsC, and acr3) was associated with arsenic resistance in Campylobacter. However, this 4-gene operon is only present in some Campylobacter isolates and other arsenic resistance mechanisms in C. jejuni have not been characterized. In this study, we determined the role of several putative arsenic resistance genes including arsB, arsC2, and arsR3 in arsenic resistance in C. jejuni and found that arsB, but not the other two genes, contributes to the resistance to arsenite and arsenate. Inactivation of arsB in C. jejuni resulted in 8- and 4-fold reduction in the MICs of arsenite and arsenate, respectively, and complementation of the arsB mutant restored the MIC of arsenite. Additionally, overexpression of arsB in C. jejuni 11168 resulted in a 16-fold increase in the MIC of arsenite. PCR analysis of C. jejuni isolates from different animals hosts indicated that arsB and acr3 (the 4-gene operon) are widely distributed in various C. jejuni strains, suggesting that Campylobacter requires at least one of the two genes for adaptation to arsenic-containing environments. These results identify ArsB as an alternative mechanism for arsenic resistance in C. jejuni and provide new insights into the adaptive mechanisms of Campylobacter in animal food production environments.",
Arsenic,1070460,"Plant proteins, minerals and trace elements of Eurycoma longifolia (Tongkat Ali) Abstract: A water extraction method has been used to extract plant proteins from the roots of Eurycoma longifolia harvested from Perak and Pahang, Malaysia. On the basis of the spectroscopic Bradford assay, Tongkat Ali Perak and Pahang contained 0.3868 and 0.9573?mg?mL-1 of crude protein, respectively. The crude proteins were separated by one dimensional 15% sodium dodecyl sulphate polyacrylamide gel electrophoresis into two (49.8 and 5.5?kD) and four (49.8, 24.7, 21.1 and 5.5?kD) protein spots for Tongkat Ali Perak and Pahang, respectively. Isoleucine was present in the highest concentration significantly. Both plant samples showed differences in the mineral and trace element profiles, but the minerals calcium, magnesium and potassium were present in the highest concentration. The highly concerned toxic metals such as arsenic and lead were not detected.",
Arsenic,2345643,"Arsenate induced differential response in rice genotypes Abstract: To study the differential response in two rice genotypes (PB1 and IR-64), hydroponically grown 14 days old plants were exposed to 50, 150 and 300µM As(V) for 24 and 96h. Accumulation of As was not significantly higher in PB1 variety except at higher concentration (300?M) and duration (96h), but up regulation of gene transcripts were higher as compared to IR-64. Inhibition in seed germination, root-shoot length, chlorophyll and protein content was observed in both varieties with increasing concentration and exposure time. PB1 variety was found more capable to detoxify As(V) through induction of antioxidant defense system and other stress related parameters (cysteine, proline content). SDS-PAGE and semi quantitative RT-PCR analysis showed significant changes in protein profile and gene expression analysis. The results suggests that various studied parameters and transcripts accumulation showed a combinatorial type of tolerance mechanism in PB1 variety to provide better protection against As(V) stress.",
Arsenic,2088499,"Detection of DNA damage based on metal-mediated molecular beacon and DNA strands displacement reaction Abstract: DNA hairpin structure probes are usually designed by forming intra-molecular duplex based on Watson-Crick hydrogen bonds. In this paper, a molecular beacon based on silver ions-mediated cytosine-Ag(+)-cytosine base pairs was used to detect DNA. The inherent characteristic of the metal ligation facilitated the design of functional probe and the adjustment of its binding strength compared to traditional DNA hairpin structure probes, which make it be used to detect DNA in a simple, rapid and easy way with the help of DNA strands displacement reaction. The method was sensitive and also possesses the good specificity to differentiate the single base mismatched DNA from the complementary DNA. It was also successfully applied to study the damage effect of classic genotoxicity chemicals such as styrene oxide and sodium arsenite on DNA, which was significant in food science, environmental science and pharmaceutical science.",
Arsenic,1677606,"Apigenin suppresses migration and invasion of transformed cells through down-regulation of C-X-C chemokine receptor 4 expression Abstract: Environmental exposure to arsenic is known to cause various cancers. There are some potential relationships between cell malignant transformation and C-X-C chemokine receptor type 4 (CXCR4) expressions. Metastasis, one of the major characteristics of malignantly transformed cells, contributes to the high mortality of cells. CXCR4 and its natural chemokine ligand C-X-C motif ligand 12 (CXCL12) play a critical role in metastasis. Therefore, identification of nutritional factors which are able to inhibit CXCR4 is important for protection from environmental arsenic-induced carcinogenesis and for abolishing metastasis of malignantly transformed cells. The present study demonstrates that apigenin (4',5,7-trihydroxyflavone), a natural dietary flavonoid, suppressed CXCR4 expression in arsenic-transformed Beas-2B cells (B-AsT) and several other types of transformed/cancer cells in a dose- and time-dependent manner. Neither proteasome nor lysosome inhibitor had any effect in reducing the apigenin-induced down-regulation of CXCR4, indicating that apigenin-induced down-regulation of CXCR4 is not due to proteolytic degradation. The down-regulation of CXCR4 is mainly due to the inhibition of nuclear factor ?B (NF-?B) transcriptional activity. Apigenin also abolished migration and invasion of transformed cells induced by CXCL12. In a xenograft mouse model, apigenin down-regulated CXCR4 expression and suppressed tumor growth. Taken together, our results show that apigenin is a novel inhibitor of CXCR4 expression. This dietary flavonoid has the potential to suppress migration and invasion of transformed cells and prevent environmental arsenic-induced carcinogenesis.",
Arsenic,626931,"Metabolic profile in workers occupationally exposed to arsenic: Role of GST polymorphisms Abstract: Arsenic is a well-known human carcinogen with a ubiquitous distribution in the natural environment. Chronic exposure to inorganic arsenic involves a biotransformation process that leds to the main excretion of organic methylated metabolites, such as monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), as well as the parental inorganic species. Interindividual variation in arsenic metabolism has been extensively reported, and polymorphisms in genes involved in such process could be related to changes in the arsenic excretion profile and the response to chronic exposures. Our analysis of the metabolic profiles in three groups of workers exposed to different arsenic exposure levels showed high amounts of inorganic arsenic and MMA in the most-exposed workers versus the least-exposed workers, in whom high amounts of DMA were observed. With respect to the role of different genetic polymorphisms in the glutathione S-transferase (GST) genes in the modulation of the urinary profiles, for the overall population only a tendency was just observed between GSTM1 null and MMA excretion as well as between GSTP1 val/val and DMA excretion.",
Arsenic,1579335,"The unexpected role of As in driving the selective growth of InAs quantum dots on GaAs Abstract: Here we show a new effect due to the Arsenic flux in the Molecular Beam Epitaxy growth of InAs Quantum Dots on GaAs(001) at temperatures higher than 500${^\circ}$C and an high As/In flux ratio. We show that, by changing and tuning the direction of the As flux on a rippled substrate, a selective growth can be obtained where the dots form only on some appropriately orientated slopes of a sequence of mounds elongated along the $[\bar{1}10]$ surface direction. Since the relative As flux intensity difference over the two opposite mound slopes is very small (2-5$\%$) the observed large effect cannot be explained simply as a pure shadowing effect and reveals instead that As, whose contribution to the modeling of growth has often been ignored or underestimated, probably for a lack of knowledge, plays a fundamental role at these growth conditions. To explain our experiment we have developed a kinetic model which explicitly takes into account the coupling between cations (In) and anions (As), and find that the very small surface gradient in the anion flux, due to the oblique evaporation on the mounded surface, is responsible for a massive drain of cations toward the surfaces anion-rich areas, thus generating the selective growth of Quantum Dots. We expect a comparable behavior for the anions of other III-V and II-VI compound semiconductors.",
Arsenic,1033736,"Induction of the 72-kD heat shock protein in organ-cultured normal human skin Abstract: To study the induction of heat shock protein (HSP) of normal human skin, the indirect immunofluorescence method, using monoclonal antibody directed against 72-kD HSP, was applied in organ-cultured normal human skin that was treated with heat, UV, or chemicals. The present study provided new evidence that HSP 72 was induced not only by heat and chemical agents, such as L-azetidine 2-carboxylic acid, and sodium arsenite, but also by ultraviolet (UV B and C). The result suggests that normal human skin has an induced protective function against numerous environmental stresses.",
Arsenic,1173548,"Arsenic- Induced disruption of blood glucose and related gene expression Abstract: Arsenic has been, and continues to be, a high priority chemical of concern at many Superfund sites, as listed by CERCLA. For many years, arsenic has been suspected of being a human teratogen; however, the several epidemiological studies that addressed this issue fell short of a conclusive association. Animal studies, on the other hand, have consistently shown arsenic to be a potent teratogen in multiple species, primarily inducing anterior neural tube defects (NTDs). Utilizing a highly inbred strain, LM/Bc/Fnn, demonstrated to be exquisitely sensitive to arsenic-induced NTDs, we are investigating the mechanisms by which this suspected human teratogen induces abnormal development. Preliminary microarray data suggest that arsenic exposure in utero uncouples oxidative phosphorylation, disrupting redox and glucose status of the developing embryo. Experimental data demonstrate that teratogenic arsenic exposure elevates maternal fasting plasma glucose concentrations to diabetic concentrations. We are testing our working hypothesis that in utero exposure to environmental arsenic alters neural tube closure by disrupting redox and glucose homeostasis, which collectively alter gene expression and cell signaling, altering development, and giving rise to the anterior NTDs.",
Arsenic,1508677,"Yeast protective response to arsenate involves the repression of the high affinity iron uptake system Abstract: Arsenic is a double-edge sword. On the one hand it is powerful carcinogen and on the other it is used therapeutically to treat acute promyelocytic leukemia. Here we report that arsenic activates the iron responsive transcription factor, Aft1, as a consequence of a defective high-affinity iron uptake mediated by Fet3 and Ftr1, whose mRNAs are drastically decreased upon arsenic exposure. Moreover, arsenic causes the internalization and degradation of Fet3. Most importantly, fet3ftr1 mutant exhibits increased arsenic resistance and decreased arsenic accumulation over the wild-type suggesting that Fet3 plays a role in arsenic toxicity. Finally we provide data suggesting that arsenic also disrupts iron uptake in mammals and the link between Fet3, arsenic and iron, can be relevant to clinical applications.",1
Arsenic,627193,"Arsenic in hair and nails of individuals exposed to arsenic-rich groundwaters in Kandal province, Cambodia Abstract: The health implications of the consumption of high arsenic groundwater in Bangladesh and West Bengal are well-documented, however, little is known about the level of arsenic exposure elsewhere in Southeast Asia, where widespread exploitation of groundwater resources is less well established. We measured the arsenic concentrations of nail and hair samples collected from residents of Kandal province, Cambodia, an area recently identified to host arsenic-rich groundwaters, in order to evaluate the extent of arsenic exposure. Nail and hair arsenic concentrations ranged from 0.20 to 6.50 microg g(-1) (n=70) and 0.10 to 7.95 microg g(-1) (n=40), respectively, in many cases exceeding typical baseline levels. The arsenic content of the groundwater used for drinking water purposes (0.21-943 microg L(-1) (n=31)) was positively correlated with both nail (r=0.74, p<0.0001) and hair (r=0.86, p<0.0001) arsenic concentrations. In addition, the nail and hair samples collected from inhabitants using groundwater that exceeded the Cambodian drinking water legal limit of 50 microg L(-1) arsenic contained significantly more arsenic than those of individuals using groundwater containing <50 microg L(-1) arsenic. X-ray absorption near edge structure (XANES) spectroscopy suggested that sulfur-coordinated arsenic was the dominant species in the bulk of the samples analysed, with additional varying degrees of As(III)-O character. Tentative linear least squares fitting of the XANES data pointed towards differences in the pattern of arsenic speciation between the nail and hair samples analysed, however, mismatches in sample and standard absorption peak intensity prevented us from unambiguously determining the arsenic species distribution. The good correlation with the groundwater arsenic concentration, allied with the relative ease of sampling such tissues, indicate that the arsenic content of hair and nail samples may be used as an effective biomarker of arsenic intake in this relatively recently exposed population.",
Arsenic,2347811,"Vegetables as a potential source of metals and metalloids for human nutrition: A case study of Momordica charantia grown in soil irrigated with domestic sewage water in Sargodha, Pakistan Abstract: Bitter gourd (Momordica charantia) grown around refuse and effluent sites of District Sargodha, Pakistan were analyzed for six metals and metalloids viz., cobalt (Co), nickel (Ni), copper (Cu), arsenic (As), zinc (Zn) and selenium (Se) by atomic absorption spectrophotometric method. Results showed that the concentrations of Co, Ni, Cu, As, Zn and Se at both sites were below the permissible limit. The levels of heavy metal and metalloid (mg/kg dry wt.) in vegetable at site-I were 0.83 for Co, 4.78 for Ni, 20.22 for Cu, 13.35 for As, 52.25 for Zn, 0.78 for Se and 0.874 for Co, 5.63 for Ni, 22.68 for Cu, 13.54 for As, 61.77 for Zn and 0.642 for Se at site-II. Transfer factors in the range of 0.049-10.97 were obtained, with Zn and Cu having the highest concentration factors of 10.97 and 2.46, respectively. The differences in uptake of these heavy metals and metalloids are ascribed to difference in tolerance to these metals by the vegetable species. The contamination factor at site-I was greater as compared to those observed at site-II. Concerning the eating habit of inhabitants, the daily intake of As, Cu, Zn and Ni was above the reference dose. Therefore, the intake of Momordica charantia was not safe for consumption in the sampling area. To reduce the health risk effects, it is suggested to treat the industrial wastes properly and phyto-extract the overload of heavy metals and metalloids from polluted sites.",
Arsenic,2022005,"Hydrogeochemical investigation in an arid region of Iran (Tabas, Central Iran) Abstract: ",
Arsenic,1352606,"SELENIUM AND OTHER ELEMENTS IN FRESH-WATER FISHES FROM THE IRRIGATED SAN-JOAQUIN VALLEY, CALIFORNIA Abstract: BIOSIS COPYRIGHT: BIOL ABS. Arsenic (As), chromium (Cr), mercury (Hg), and selenium (Se) were measured in composite whole-body samples of five fishes-bluegill (Lepomis macrochirus), common carp (Cyprinus carpio), mosquitofish (Gambusia affinis), largemouth bass (Micropterus salmoides), and Sacramento blackfish (Orthodon microlepidotus)-from the San Joaquin River system to determine if concentrations were levated from exposure to agricultural subsurface (tile) drainage. Except for Cr, the concentrations of these elements in fishes from one or more sites were elevated; however, only Se approached concentrations that may adversely affect survival, growth, or reproduction in warm water fishes. Moreover, only Se among the four measured elements exhibited a geographic (spatial) pattern that coincided with known inflows of tile drainage to the San Joaquin River and its tributaries. Historical data from the Grassland Water District (Grasslands; a region exposed to concentrated tile drainage) suggested that",
Arsenic,1255507,"Arsenic speciation and trace element analysis of the volcanic río Agrio and the geothermal waters of Copahue, Argentina Abstract: Surface water originating from the Copahue volcano crater-lake was analysed for total arsenic and four arsenic species: arsenite (iAs(III)), arsenate (iAs(V)), monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)) and other trace elements (Fe, Mn, V, Cr, Ni, Zn). A novel in-field technique for the preconcentration and separation of four arsenic species was, for the first time, used for the analysis of geothermal and volcanic waters. Total arsenic levels along the río Agrio ranged from &lt;0.2-3783?g/l As(T). The highest arsenic levels were recorded in the el Vertedero spring (3783?g/l As(T)) on the flank of the Copahue volcano, which feeds the acidic río Agrio. Arsenite (H(3)AsO(3)) predominated along the upper río Agrio (78.9-81.2% iAs(III)) but the species distribution changed at lago Caviahue and arsenate (H(2)AsO(4)(-)) became the main species (51.4-61.4% iAs(V)) up until Salto del Agrio. The change in arsenic species is potentially a result of an increase in redox potential and the formation of iron-based precipitates. Arsenic speciation showed a statistically significant correlation with redox potential (r=0.9697, P=0.01). Both total arsenic and arsenic speciation displayed a statistically significant correlation with vanadium levels along the river (r=0.9961, P=0.01 and r=0.8488, P=0.05, respectively). This study highlights that chemical speciation analysis of volcanic waters is important in providing ideas on potential chemical toxicity. Furthermore there is a need for further work evaluating how arsenic (and other trace elements), released in volcanic and geothermal streams/vents, impacts on both biota and humans (via exposure in thermal pools or consuming commercial drinking water).",
Arsenic,1018858,"Toxicity and bioaccumulation of arsenic and chromium in epigean and hypogean freshwater macroinvertebrates Abstract: Lethal toxicity levels of two inorganic water pollutants, chromium (Cr6+) and arsenic (As3+), were determined toward six freshwater macroinvertebrate species collected from a single field site. Crustaceans were represented by two amphipod species, an epigean one (Gammarus fossarum) and a hypogean one (Niphargus rhenorhodanensis), and by an isopod species (Asellus aquaticus). There were two insect larvae, Heptagenia sulphurea (Ephemeroptera) and Hydropsiche pellucidula (Trichoptera) and a snail, Physa fontinalis. Median lethal concentrations (LC50s) were determined over 96-h and 240-h periods for chromium and over a 240-h period for arsenic. Arsenic bioaccumulation was studied, too. The macroinvertebrates tested showed a wide range of sensitivity and bioaccumulation. A comparison between 96-h and 240-h experiments demonstrated that there was an increase in toxicity values following a longer time exposure for chromium. Also chromium was more toxic toward crustaceans than arsenic; conversely, arsenic was more toxic for the insect larvae and snail tested here. The lethal concentrations determined for the two metals were discussed and compared to results from other toxicity studies. The use of such macroinvertebrates, collected in the field and tested for longer exposure periods than within the standardized 96-h tests, should provide more suitable results for monitoring the general environmental quality of freshwater systems.",
Arsenic,1340905,"Tudor-SN and ADAR1 are components of cytoplasmic stress granules Abstract: Hyperediting by adenosine deaminases that acts on RNA (ADARs) may result in numerous Adenosine-to-Inosine (A-to-I) substitutions within long dsRNA. However, while countless RNAs may undergo hyperediting, the role for inosine-containing hyperedited dsRNA (IU-dsRNA) in cells is poorly understood. We have previously shown that IU-dsRNA binds specifically to various components of cytoplasmic stress granules, as well as to other proteins such as Tudor Staphylococcal Nuclease (Tudor-SN). Tudor-SN has been implicated in diverse roles in mammalian cells, including transcription, splicing, RNAi, and degradation. Moreover, we have shown that Tudor-SN interacts directly with stress granule proteins. Here we show that Tudor-SN localizes to cytoplasmic stress granules in HeLa cells undergoing arsenite-induced oxidative stress, or following transfection with long dsRNA (poly[IC]), which initiates an interferon cascade. We additionally demonstrate a novel interaction between Tudor-SN and ADAR1. Finally, we show that ADAR1 is also localized to stress granules in HeLa cells following various stresses.",
Arsenic,2278822,"Assessing the influence of compost and biochar amendments on the mobility and toxicity of metals and arsenic in a naturally contaminated mine soil Abstract: Amending contaminated soils with organic wastes can influence trace element mobility and toxicity. Soluble concentrations of metals and arsenic were measured in pore water and aqueous soil extracts following the amendment of a heavily contaminated mine soil with compost and biochar (10% v:v) in a pot experiment. Speciation modelling and toxicity assays (Vibrio fischeri luminescence inhibition and Lolium perenne germination) were performed to discriminate mechanisms controlling metal mobility and assess toxicity risk thereafter. Biochar reduced free metal concentrations furthest but dissolved organic carbon primarily controlled metal mobility after compost amendment. Individually, both amendments induced considerable solubilisation of arsenic to pore water (>2500 ?g l(-1)) related to pH and soluble phosphate but combining amendments most effectively reduced toxicity due to simultaneous reductions in extractable metals and increases in soluble nutrients (P). Thus the measure-monitor-model approach taken determined that combining the amendments was most effective at mitigating attendant toxicity risk.",
Arsenic,1353316,"In-vitro shoot regeneration via caulogenesis in fern, Pteris vittata L Abstract: An attempt was made to standardize the protocol for the shoot regeneration via caulogenesis in Pteris vittata L. employing leaf primordium explants. Calli were induced on Murashige and Skoog's (MS) and Parkers and Thompson's (P and T) media supplemented with different combinations of 2, 4-dichlorophenoxyaceticacid (2, 4-D), 6-benzylaminopurine (BAP), alpha-naphthalene acetic acid (NAA) and Indole-3-acetic acid (IAA). A combination of full strength MS medium with 2, 4-D (2.26 microM) and BAP (2.22 microM) was found to be ideal for profuse callusing (80%) against other combinations. More shoot differentiation (2.8 +/- 0.06) was achieved from the calli on one-fourth strength of P and T media fortified with BAP (4.44 microM) and NAA (2.68 microM) when compared to other combinations but statistically not significant.",
Arsenic,656670,"Comparative genomic hybridization study of arsenic-exposed and non-arsenic-exposed urinary transitional cell carcinoma Abstract: To compare the differences in DNA aberrations between arsenic-exposed and non-arsenic-exposed transitional cell carcinoma (TCC), we analyzed 19 arsenic-exposed and 29 non-arsenic-exposed urinary TCCs from Chi-Mei Hospital using comparative genomic hybridization. DNA aberrations were detected in 42 TCCs including 19 arsenic-exposed and 23 non-arsenic-exposed TCCs. Arsenic-exposed TCCs had more changes than unexposed TCCs (mean+/-SD, 6.6+/-2.9 vs. 2.9+/-2.2). Arsenic exposure was significantly associated with the number of DNA aberrations after adjustment for tumor stage, tumor grade and cigarette smoking in multiple regression analysis. The most frequent DNA gains, which were strikingly different between arsenic-exposed and non-arsenic-exposed TCCs, included those at 1p, 4p, 4q and 8q. A much higher frequency of DNA losses in arsenic-exposed TCCs compared with non-arsenic-exposed TCCs was observed in 10q, 11p and 17p. Chromosomal loss in 17p13 was associated not only with arsenic exposure, but also with tumor stage and grade. The p53 immunohistochemistry staining showed that chromosome 17p13 loss was associated with either p53 no expression (25%) or p53 overexpression (75%). The findings suggest that long-term arsenic exposure may increase the chromosome abnormality in TCC, and 17p loss plays an important role in arsenic-induced urinary carcinogenesis.",
Arsenic,1028902,"Arsenicosis status and urinary malondialdehyde (MDA) in people exposed to arsenic contaminated-coal in China Abstract: The current arsenic exposure condition, arsenicosis prevalence, urinary arsenic and MDA (malondialdehyde) concentrations in people were studied. The study area, a village in Xing Ren County in Guizhou Province, PR China, is a coal-borne arsenicosis endemic area that was identified several decades ago. The residents in Xing Ren have been using coal containing high arsenic levels all their life. Urinary arsenic levels of villagers were 192.2+/-22 microg/g creatinine (n=113) in the coal-borne endemic area (Xing Ren county) and were significantly higher than 63.6+/-5.9 microg/g creatinine (n=30) in a neighbouring control site (a village in Xing Yi county). The urinary MDA concentrations of villagers from the endemic area were also significantly higher compared to those of the control area. There was a strong correlation between age and urinary arsenic and MDA concentrations in the endemic area of Xing Ren; urinary arsenic and MDA levels decreased with age. Fifty out of 113 (44.3%) villagers in the endemic area had arsenicosis symptoms and the prevalence in villagers older than 40 y was 100% in male (92.2% overall). Urinary MDA concentration was significantly higher in people with arsenicosis symptoms in the endemic areas. Oxidative stress (urinary MDA concentration) was strongly related to arsenic exposure but not to the age and smoking habit. Higher urinary arsenic and MDA levels in younger villagers from the endemic area suggest that they are having a higher exposure to coal-borne emitted arsenic because they spend more time indoor. There is an urgent need to develop proper intervention methods in the Guizhou endemic areas in order to reduce the risk to the local communities who are still using arsenic contaminated-coal.",
Arsenic,2215739,"Dissimilatory antimonate reduction and production of antimony trioxide microcrystals by a novel microorganism Abstract: Antimony (Sb) is a metalloid that has been exploited by humans since the beginning of modern civilization. The importance of Sb to such diverse industries as nanotechnology and health is underscored by the fact that it is currently the ninth-most mined metal worldwide. Although its toxicity mirrors that of its Group 15 neighbor arsenic, its environmental chemistry is very different, and, unlike arsenic, relatively little is known about the fate and transport of Sb, especially with regard to biologically mediated redox reactions. To further our understanding of the interactions between microorganisms and Sb, we have isolated a bacterium that is capable of using antimonate [Sb(V)] as a terminal electron acceptor for anaerobic respiration, resulting in the precipitation of antimonite [Sb(III)] as microcrystals of antimony trioxide. The bacterium, designated strain MLFW-2, is a sporulating member of a deeply branching lineage within the order Bacillales (phylum Firmicutes). This report provides the first unequivocal evidence that a bacterium is capable of conserving energy for growth and reproduction from the reduction of antimonate. Moreover, microbiological antimonate reduction may serve as a novel route for the production of antimony trioxide microcrystals of commercial significance to the nanotechnology industry.",
Arsenic,1579332,"Arsenite suppression of BMP signaling in human keratinocytes Abstract: Arsenic, a human skin carcinogen, suppresses differentiation of cultured keratinocytes. Exploring the mechanism of this suppression revealed that BMP-6 greatly increased levels of mRNA for keratins 1 and 10, two of the earliest differentiation markers expressed, a process prevented by co-treatment with arsenite. BMP also stimulated, and arsenite suppressed, mRNA for FOXN1, an important transcription factor driving early keratinocyte differentiation. Keratin mRNAs increased slowly after BMP-6 addition, suggesting they are indirect transcriptional targets. Inhibition of Notch1 activation blocked BMP induction of keratins 1 and 10, while FOXN1 induction was largely unaffected. Supporting a requirement for Notch1 signaling in keratin induction, BMP increased levels of activated Notch1, which was blocked by arsenite. BMP also greatly decreased active ERK, while co-treatment with arsenite maintained active ERK. Inhibition of ERK signaling mimicked BMP by inducing keratin and FOXN1 mRNAs and by increasing active Notch1, effects blocked by arsenite. Of 6 dual-specificity phosphatases (DUSPs) targeting ERK, two were induced by BMP unless prevented by simultaneous exposure to arsenite and EGF. Knockdown of DUSP2 or DUSP14 using shRNAs greatly reduced FOXN1 and keratins 1 and 10 mRNA levels and their induction by BMP. Knockdown also decreased activated Notch1, keratin 1 and keratin 10 protein levels, both in the presence and absence of BMP. Thus, one of the earliest effects of BMP is induction of DUSPs, which increases FOXN1 transcription factor and activates Notch1, both required for keratin gene expression. Arsenite prevents this cascade by maintaining ERK signaling, at least in part by suppressing DUSP expression.",
Arsenic,1030045,"The environmental and public health risks associated with arsenical use in animal feeds Abstract: Arsenic exposures contribute significantly to the burden of preventable disease worldwide, specifically related to increased risks of cancer, diabetes, and cardiovascular disease. Most exposures are associated with natural contamination of groundwater, which is difficult to mitigate when these sources are used for drinking water. An anthropogenic source of arsenic exposure stems from the widespread use of arsenical drugs in food-animal production in the United States and China, among many countries. This use results in residual contamination of food products from animals raised with the drugs, as well as environmental contamination associated with disposal of wastes from these animals. Land disposal of these wastes can contaminate surface and ground water, and the conversion of animal wastes into fertilizer pellets for home use as well as the introduction of animal waste incinerators may increase opportunities for exposure. As an intentional additive to animal feed, use of arsenical drugs is a preventable source of human exposure. The domestic practice of using these drugs in poultry production has been the subject of media attention and limited research, though the use of these drugs in domestic swine production and in the rapidly growing foreign animal production industry remains largely uncharacterized. This continued expansion of arsenical drug use may likely increase the burden of global human arsenic exposure and risk.",
Arsenic,1351603,"Detection of Zinc, Lead, Cadmium and Arsenic in Dabbling Ducks from Durango, Mexico Abstract: ",
Arsenic,787866,"Lead acetate and arsenic trioxide induce instability of microsatellites at three different fragile sites (6q21, 9q32-9q33 and 15p14) within the genome of the rat Abstract: Human exposure to metals is of increasing concern due to the well-documented toxic and carcinogenic effects of metals and metal compounds, and the rising environmental levels due to industrial processes and pollution. It has been reported that metals can be genotoxic by several modes of action including generation of reactive oxygen species and inhibition of DNA repair. The aim of this study was to evaluate microsatellite instability (MSI) in three microsatellite loci (D6mit3, D9mit2 and D15Mgh1) located within three common fragile sites in the genome of the laboratory rat (6q21, 9q32-9q33 and 15p14) exposed to acute and chronic doses of a metal salt (lead acetate trihydrate) and a metalloid oxide (arsenic trioxide). In the acute and sub-chronic studies with the two compounds, MSI was observed in the three loci as deletions or additions of microsatellite repeats. The percentages of MSI were 36.4% and 42.1% for lead acetate and arsenic trioxide, respectively. Results of the present work indicate that the microsatellites located within fragile sites provide a convenient assay system to detect changes in DNA sequences resulting from exposure to genotoxic agents.",
Arsenic,1251307,"Carbonic anhydrase inhibitors: inhibition of human and murine mitochondrial isozymes V with anions Abstract: In addition to sulfonamides, metal complexing anions represent the second class of inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). The first inhibition study of the mitochondrial isozyme CA V (of murine and human origin) with anions is reported here. Inhibition data of the cytosolic isozymes CA I and CA II as well as the membrane-bound isozyme CA IV with a large number of anionic species such as halides, pseudohalides, bicarbonate, nitrate, hydrosulfide, arsenate, sulfamate, and sulfamidate and so on, are also provided for comparison. Isozyme V has an inhibition profile by anions completely different to those of CA I and IV, but similar to that of hCA II, which may have interesting physiological consequences. Similarly to hCA II, the mitochondrial isozymes show micro-nanomolar affinity for sulfonamides such as sulfanilamide and acetazolamide.",
Arsenic,627956,"Ingested arsenic, cigarette smoking, and lung cancer risk: A follow-up study in arseniasis-endemic areas in Taiwan Abstract: CONTEXT: Arsenic has been documented as a lung carcinogen in humans in only a few follow-up studies, which were limited by a small number of cases or the lack of information on cigarette smoking. OBJECTIVES: To elucidate the dose-response relationship between ingested arsenic and lung cancer and to assess the effect of cigarette smoking on the arsenic-lung cancer association. DESIGN, SETTING, AND PARTICIPANTS: A total of 2503 residents in southwestern and 8088 in northeastern arseniasis-endemic areas in Taiwan were followed up for an average period of 8 years. Information on arsenic exposure, cigarette smoking, and other risk factors was collected at enrollment through standardized questionnaire interview. MAIN OUTCOME MEASURES: The incidence of lung cancer was ascertained through linkage with national cancer registry profiles in Taiwan (January 1985-December 2000). The joint effect of arsenic and cigarette smoking was estimated by both etiologic fraction and synergy index. RESULTS: There were 139 newly diagnosed lung cancer cases during a follow-up period of 83,783 person-years. After adjustment for cigarette smoking and other risk factors, there was a monotonic trend of lung cancer risk by arsenic level in drinking water of less than 10 to 700 microg/L or more (P<.001). The relative risk was 3.29 (95% confidence interval, 1.60-6.78) for the highest arsenic level compared with the lowest. The etiologic fraction of lung cancer attributable to the joint exposure of ingested arsenic and cigarette smoking ranged from 32% to 55%. The synergy indices ranged from 1.62 to 2.52, indicating a synergistic effect of ingested arsenic and cigarette smoking on lung cancer. CONCLUSIONS: There was a significant dose-response trend of ingested arsenic on lung cancer risk, which was more prominent among cigarette smokers. The risk assessment of lung cancer induced by ingested arsenic should take cigarette smoking into consideration.",
Arsenic,1357711,"Metal Induction of Heme Oxygenase Abstract: Metal induction of heme-oxygenase was discussed. Molecular mechanisms for induction of microsomal heme-oxygenase activity by metals were summarized. Induction of microsomal heme-oxygenase involves de-novo synthesis of messenger RNA (mRNA) and protein. Heme-oxygenase induction is inhibited when thiol compounds such as cysteine and glutathione are coadministered. Heme-oxygenase induction by metals is enhanced in tissues containing reduced amounts of thiols. Studies of the effects of cobalt (7440484), cadmium (7440439), tin (7440315), nickel (7440020), arsenic (7440382), and mercury (7439976) and miscellaneous metals on heme-oxygenase in rats were reviewed. These have shown that induction of heme-oxygenase activity in the liver, heart, lung, kidney, adrenals, and other organs is a nonspecific toxic response. Cobalt(2+) and cadmium(2+) (Cd+2) have been shown to be potent inducers of heme-oxygenase; however, Cd+2 inhibited testicular heme-oxygenase activity. Tin (2+), nickel(2+), and arsenic(3+) ions were potent inducers of heme-oxygenase activity, whereas mercury(2+) was a potent inducer of hepatic heme-oxygenase. Actinomycin-D, cycloheximide, and cysteine significantly inhibited induction of renal heme-oxygenase by Ni+2. A significant synergistic induction of renal heme-oxygenase activity occurred when diethyldithiocarbamate (DDC) was administered simultaneously with nickel. DDC plus nickel also synergistically increased hepatic heme-oxygenase and greatly increased accumulation of nickel in the liver. The author concludes that induction of heme-oxygenase in rats is a nonspecific toxic response to parenteral administration of various metal compounds and requires de-novo synthesis of mRNA. The induction mechanism may involve binding of metal ions to thiol containing moieties.",
Arsenic,1015685,"Risk from winter vegetables and pulses produced in arsenic endemic areas of Nadia District: Field study comparison with market basket survey Abstract: Arsenic contaminated groundwater uses for irrigation potentially lead the incidence of arsenic into food chain. In present study we examined total arsenic concentrations in 32 types of vegetables and 7 types of pulses. Range of total arsenic concentration in edible parts of vegetables collected from grown fields was 0.114-0.910 mg/kg. Highest arsenic values were in spinach 0.910 mg/kg. Vegetable samples were grouped into leafy, non-leafy-fruity, root-tubers. 18 common types of vegetables and pulses were collected through market basket survey, total arsenic were approximately 100 mg lower than those observed for the vegetables collected from the fields.",
Arsenic,1677540,"Arsenic removal using natural biomaterial-based sorbents Abstract: Arsenic contamination of water is a major problem worldwide. A possible solution can be approached through developing new sorbents based on cost-effective and environmentally friendly natural biomaterials. We have developed new sorbents based on biomaterial impregnation with iron oxyhydroxide. In this study, raw peat material, iron-modified peat, iron-modified biomass (shingles, straw, sands, cane and moss) as well as iron humate were used for the removal of arsenate from contaminated water. The highest sorption capacity was observed in iron-modified peat, and kinetic studies indicated that the amount of arsenic sorbed on this material exceeds 90 % in 5 h. Arsenate sorption on iron-modified peat is characterised by the pseudo-second-order mechanism. The results of arsenic sorption in the presence of competing substances indicated that sulphate, nitrate, chloride and tartrate anions have practically no influence on As(V) sorption onto Fe-modified peat, whereas the presence of phosphate ions and humic acid significantly lowers the arsenic removal efficiency.",
Arsenic,1579294,"Association of urinary monomethylated arsenic concentration and risk of hypertension: A cross-sectional study from arsenic contaminated areas in northwestern China Abstract: <strong>BACKGROUND: </strong>Although some studies mainly from Taiwan, Bangladesh and the United States, have suggested a consistent dose-response increase in the prevalence of hypertension with increasing arsenic exposure, the association between chronic environmental arsenic exposure and the risk of hypertension is still inconclusive. Most of the studies discussed the association from the point of view of arsenic concentration in drinking water or cumulative arsenic exposure (CAE), few involved arsenic speciation into the discussion. In this cross-sectional study, we evaluated the potential association between environmental arsenic exposure through drinking water and the prevalence of hypertension by analyzing not only CAE but also urinary arsenic speciation, and provided data on arsenic exposure and hypertension from mainland of China.<br /><br /><strong>METHODS: </strong>A cross-sectional study was conducted in one of the arsenic contaminated areas in the northwest of China. Among a total of 1005 residents who voluntarily participated in the study, 604 of eligible subjects were confirmed and interviewed door to door. Standing height, body weight, and blood pressure were measured. First void urine was collected and measured for the concentration of urinary arsenic speciation. CAE was calculated in a subpopulation of 360 subjects with detailed water consumption history. The association between urinary arsenic speciation, CAE and the risk of hypertension were analyzed by multiple logistic regressions.<br /><br /><strong>RESULTS: </strong>We found that the levels of urinary arsenic species of inorganic arsenic (iAs), monomethylated arsenic (MMA), dimethylated arsenic (DMA) and total arsenic (tAs) were significantly correlated with systolic or pulse blood pressure. A positive relationship was found between the highest tertile of CAE and hypertension in a dose-dependent manner. Subjects with higher concentration of urinary MMA or lower percentage of DMA tended to be liable to suffer from hypertension. A significant increasing trend of the risk of hypertension with increasing tertiles of MMA concentration was also observed in the logistic regression models both before and after adjustment for confounders.<br /><br /><strong>CONCLUSIONS: </strong>Our findings suggested that arsenic exposure, especially high level of CAE, was positively associated with the prevalence of hypertension, and that higher concentration of urinary MMA might be related to the increased susceptibility to hypertension.",
Arsenic,2298686,"Heavy metals levels in fish from aquaculture farms and risk assessment in Lhasa, Tibetan Autonomous Region of China Abstract: Fish is consumed as a common food by humans due to its nutritional and therapeutic benefits. However, they can accumulate toxic chemicals (such as heavy metals, persistent organic pollutants) from water and food chain. Very few studies have been investigated on heavy metal contents in fish from Tibetan Autonomous Region of China. In order to study heavy metals levels in fish from aquaculture farms and evaluate the risk that human consume fish in this area, we collected four types of aquaculture fish species (6 big-head carps, 5 grass carps, 5 carps and 5 tilapias) from fisheries around Lhasa city in this study. 9 heavy metals (Cr, As, Cd, Pb, Cu, Ba, Co, Mn and V) in different tissues of fish were determined by an inductively coupled plasma mass spectrometer. Cr, Ba, Co, Mn and V could easily accumulate in the gill, and Cu was detected in the hearts of all the fishes. Toxic metal (As, Cd and Pb) contents were higher in the liver than those in other tissues, heavy metal levels were the lowest in the muscle among all tissues. Most of heavy metal concentrations in the tilapia tissues were higher than those in other fish tissues, especially arsenic. Arsenic content in the tilapia samples was ~2-4 times higher than the maximum levels (MLs) of contaminants in the national standard, and other metals were all lower than the MLs. Compared the estimated daily intake of heavy metals through fish consumption with tolerable daily intakes recommended by FAO, the metals daily intake of As, Cd and Pb from fish consumption might not pose serious health risk to the local inhabitants. It is therefore necessary to determine the dose level for human, which is considered to be taken daily over a lifetime without adverse effects.",
Arsenic,1170726,"Effects of arsenic on endothelial cell activation and Acetylated-LDL uptake by macrophages Abstract: Cardiovascular disease (CVD) is an important cause of morbidity and mortality in the developed world. Arsenic is widely dispersed in the environment, and epidemiological studies have linked chronic arsenic exposure to a range of CVDs including atherosclerosis, ischemic heart disease, peripheral vascular disease and hypertension. Atherosclerosis is an inflammatory disease, characterized by release of cytokines and chemokines and activation of endothelial cells. We used a combination of ELISA, flow cytometry and Western blot analysis to study endothelial cell activation in human aortic endothelial cells (HAECs). Our results showed that arsenic decreased expression of VE-cadherin, a protein that is responsible for maintaining tight junctions between the endothelial cells. This could lead to increased permeability of the endothelial barrier. We also found that arsenic modulated the expression of vascular cell adhesion molecule (VCAM-1) and interleukin-6 (IL-6) at concentrations as low as 1 uM at various time points up to 48 h. These events could lead to an increase in transmigration of monocytes across the endothelium. The monocytes are differentiated into macrophages within the intima of the blood vessel and play a key role in formation of foam cells. Using flow cytometry, we assessed the effects of arsenic exposure on uptake of acetylated LDL (Ac-LDL) by macrophages. Differentiated THP-1 cells were treated with arsenic-conditioned medium from HAECs and mouse macrophage cells (RAW264.7) were treated with serum from atherosclerotic apoE-/-LDLR-/- mice that had been exposed to arsenic in drinking water for 18 weeks. Arsenic treatment led to increased Ac-LDL uptake in both cases suggesting that endothelial activation by arsenic could facilitate foam cell formation.",
Arsenic,1360109,"Thorotrast and the liver: A reminder Abstract: HEEP COPYRIGHT: BIOL ABS. New insights into carcinogenesis might by gained by further study of Thorotrast-induced human neoplasia. The role of immune mechanisms in the induction of these tumors is uncertain. Thorotrast neoplasms may be RES tumors of multicentric origin. Although exposure to ionizing radiation would appear to be the primary inciting mechanism of Thorotrast carcinogenesis in the liver, no association between liver cell carcinoma or cholangiocarcinoma and atomic bomb exposure was identified in an autopsy series from Hiroshima and Nagasaki (Japan). The possibility of a foreign body or chemical reaction, resembling As-induced malignancy, was also suggested. Although knowledge of vinyl chloride-induced hepatotoxicity is currently limited, the clinical features of vinyl chloride liver disease resemble those associated with Thorotrast. Similarities in latent period and in the development of fibrosis, cirrhosis and angiosarcoma are striking. Whether vinyl chloride-induced carcinogenesis and hepatic injury share features other than clinical expression with Thorotrast remains to be determined. Regardless of the mechanisms of Thorotrast sequelae, it is apparent that carriers represent a population at risk for the development of liver disease and deserves the attention of hepatologists.",
Arsenic,1509365,Preparation of Prussian Blue Analogue Modified Porous Ceramic Balls and Its Application in As Adsorption Abstract: ,
Arsenic,1031817,"Multistage modeling of lung cancer mortality among arsenic-exposed copper-smelter workers Abstract: Multistage modeling incorporating a time-dependent exposure pattern is applied to lung cancer mortality data obtained from a cohort of 2802 arsenic-exposed copper-smelter workers who worked 1 or more years during the period 1940-1964 at a copper smelter at Tacoma, Washington. The workers were followed for death through 1976. There were 100 deaths due to lung cancer during the follow-up period. Exposures to air arsenic levels measured in micrograms/m3 were estimated from departmental air arsenic and workers urinary arsenic measurements. Relationships of different temporal variables with excess death rates are examined to judge qualitatively the implications of the multistage cancer process. Analysis to date indicates a late stage effect of arsenic although an additional early stage effect cannot be ruled out.",
Arsenic,1030840,"Association of oxidative stress with arsenic methylation in chronic arsenic-exposed children and adults Abstract: Though oxidative stress is recognized as an important pathogenic mechanism of arsenic, and arsenic methylation capacity is suggested to be highly involved in arsenic-related diseases, the association of arsenic methylation capacity with arsenic-induced oxidative stress remains unclear. To explore oxidative stress and its association with arsenic methylation, cross-sectional studies were conducted among 208 high and 59 low arsenic-exposed subjects. Levels of urinary arsenic species [inorganic arsenic (iAs), monomethylated arsenic (MMA) and dimethylated arsenic (DMA)] were determined by hydride generation atomic absorption spectrometry. Proportions of urinary arsenic species, the first methylation ratio (FMR) and the secondary methylation ratio (SMR) were used as indicators for arsenic methylation capacity. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations were analyzed by enzyme-linked immunosorbent assay kits. Reduced glutathione (GSH) levels and superoxide dismutase (SOD) activity in whole blood were determined to reflect anti-oxidative status. The high arsenic-exposed children and adults were significantly increased in urinary 8-OHdG concentrations but decreased in blood GSH levels compared with the low exposed children and adults. In multiple linear regression models, blood GSH levels and urinary 8-OHdG concentrations of arsenic-exposed children and adults showed strong associations with the levels of urinary arsenic species. Arsenic-exposed subjects in the lower and the upper quartiles of proportions of urinary arsenic species, FMR or SMR were significantly different in urinary 8-OHdG, blood GSH and SOD. The associations of arsenic methylation capacity with 8-OHdG, GSH and SOD were also observed in multivariate regression analyses. These results may provide linkage between arsenic methylation capacity and oxidative stress in humans and suggest that adverse health effects induced by arsenic are related to arsenic methylation through oxidative stress.",
Arsenic,710874,"Association of XPD/ERCC2 G23591A and A35931C polymorphisms with skin lesion prevalence in a multiethnic, arseniasis-hyperendemic village exposed to indoor combustion of high arsenic coal Abstract: More than 2,000 arsenic-related skin lesions (as at 2002) in a few villages of China's Southwest Guizhou Autonomous Prefecture represent a unique case of endemic arseniasis related with indoor combustion of high-arsenic coal. The skin lesion prevalence was significantly higher in ethnic Han villagers than in ethnic Hmong villagers. This study was focused on a possible involvement of XPD/ERCC2 G23591A and A35931C polymorphisms in risk modulation of skin lesions and in the body burden of As in this unique case of As exposure. G23591A and A35931C were genotyped by a PCR-based procedure. Total As contents in hair and urine samples as well as environmental samples of the homes of the two ethnic clans were analysed. A significant higher presentation of A/A35931 (homozygous wild) genotype in both clans was found in skin lesion patients, compared with their asymptomatic fellow villagers (67.1 vs. 46.3%, OR 2.36, 95% CI 1.35-4.14, P=0.002). Interestingly, the population frequencies of the A/A35931 genotype did not show significant differences between ethnic Han villagers and their Hmong neighbours (47.1 vs. 45.5%). Very low frequencies of homozygous and heterozygous variant genotypes of G23591A were recorded in the residents in target village. G/A23591 and A/A23591 were detected only in 3.2% (8/244) and 0.8% (2/244) of the villagers, respectively. The polymorphic status at the locus of A35931C might modulate the risk for arsenic-related skin lesions in the investigated groups.",
Arsenic,1508699,"Ochres and earths: Matrix and chromophores characterization of 19th and 20th century artist materials Abstract: The present paper describes the main results obtained from the characterization of a wide range of natural and synthetic ochre samples used in Portugal from the 19th to the 20th century, including powder and oil painting samples. The powder ochre samples came from several commercial distributors and from the collection of Joaquim Rodrigo (1912-1997), a leading Portuguese artist, particularly active during the sixties and seventies. The micro-samples of oil painting tubes came from the Museu Nacional de Arte Contemporânea-Museu do Chiado (National Museum of Contemporary Art-Chiado Museum) in Lisbon and were used by Columbano Bordalo Pinheiro (1857-1929), one of the most prominent naturalist Portuguese painters. These tubes were produced by the main 19th century colourmen: Winsor &amp; Newton, Morin et Janet, Maison Merlin, and Lefranc. The samples have been studied using ?-Fourier Transform Infrared Spectroscopy (?-FTIR), Raman microscopy, ?-Energy Dispersive X-ray fluorescence (?-EDXRF), and X-ray diffraction (XRD). The analyzed ochres were found to be a mixture of several components: iron oxides and hydroxides in matrixes with kaolinite, gypsum and chalk. The results obtained allowed to identify and characterize the ochres according to their matrix and chromophores. The main chromophores where identified by Raman microscopy as being hematite, goethite and magnetite. The infrared analysis of the ochre samples allowed to divide them into groups, according to the composition of the matrix. It was possible to separate ochres containing kaolinite matrix and/or sulfate matrix from ochres where only iron oxides and/or hydroxides were detected. ?-EDXRF and Raman were the best techniques to identify umber, since the presence of elements such as manganese is characteristic of these pigments. ?-EDXRF also revealed the presence of significant amounts of arsenic in all Sienna tube paints.",
Arsenic,2345621,"DNA adsorption by magnetic iron oxide nanoparticles and its application for arsenate detection Abstract: Iron oxide nanoparticles adsorb fluorescently labeled DNA oligonucleotides via the backbone phosphate and quench fluorescence. Arsenate displaces adsorbed DNA to increase fluorescence, allowing detection of arsenate down to 300 nM. This is a new way of using DNA: analyte recognition relies on its phosphate instead of the bases.",
Arsenic,1034300,"Intracellular distribution of 73,000 and 72,000 dalton heat shock proteins in HeLa cells Abstract: Intracellular localization of 73,000 and 72,000 dalton heat shock proteins (HSP73/72) in HeLa cells that were heat shocked or treated with chemical stressors was investigated using indirect immunofluorescent staining. The antiserum used specifically recognized the HSP73/72 in HeLa cells, and HSPs were increased by heating cells at 42 degrees C for 2 or 4 h and by prior treatment with chemical stressors (sodium arsenite, cadmium chloride, 8-hydroxyquinoline and ethanol). There was diffuse cytoplasmic staining at 37 degrees C, whereas nucleoli were stained brightly when cells were heated at 42 degrees C for 2 h. This rapid accumulation of HSP73/72 in the nucleoli was not inhibited by cycloheximide (50 micrograms/ml). Translocation of HSPs to the nucleoli was specific for heat because no translocation was induced by treatment with chemical stressors. When the cells were returned to 37 degrees C after heating, the HSPs in their nucleoli disappeared rapidly and diffuse cytoplasmic staining was present after 6-9 h. Our results suggest that the transient accumulation of HSP73/72 in HeLa cell nucleoli that is induced by heat shock is not correlated with the development of thermotolerance obtained in other cell systems.",
Arsenic,710864,"Association between arsenic exposure and plasma cholinesterase activity: A population based study in Bangladesh Abstract: Arsenic is a potent pollutant that has caused an environmental catastrophe in certain parts of the world including Bangladesh where millions of people are presently at risk due to drinking water contaminated by arsenic. Chronic arsenic exposure has been scientifically shown as a cause for liver damage, cancers, neurological disorders and several other ailments. The relationship between plasma cholinesterase (PChE) activity and arsenic exposure has not yet been clearly documented. However, decreased PChE activity has been found in patients suffering liver dysfunction, heart attack, cancer metastasis and neurotoxicity. Therefore, in this study, we evaluated the PChE activity in individuals exposed to arsenic via drinking water in Bangladesh.<br /><br /> A total of 141 Bangladeshi residents living in arsenic endemic areas with the mean arsenic exposure of 14.10 +/- 3.27 years were selected as study subjects and split into tertile groups based on three water arsenic concentrations: low (&lt; 129 microg/L), medium (130-264 microg/L) and high (&gt; 265 microg/L). Study subjects were further sub-divided into two groups (&lt;or=50 microg/L and &gt; 50 microg/L) based on the recommended upper limit of water arsenic concentration (50 microg/L) in Bangladesh. Blood samples were collected from the study subjects by venipuncture and arsenic concentrations in drinking water, hair and nail samples were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PChE activity was assayed by spectrophotometer.<br /><br /> Arsenic concentrations in hair and nails were positively correlated with the arsenic levels in drinking water. Significant decreases in PChE activity were observed with increasing concentrations of arsenic in water, hair and nails. The average levels of PChE activity in low, medium and high arsenic exposure groups were also significantly different between each group. Lower levels of PChE activity were also observed in the &gt; 50 microg/L group compared to the &lt;or=50 microg/L group. Moreover, PChE activity was significantly decreased in the skin (+) symptoms group compared to those without (-).<br /><br /> We found a significant inverse relationship between arsenic exposure and PChE activity in a human population in Bangladesh. This research demonstrates a novel exposure-response relationship between arsenic and PChE activity which may explain one of the biological mechanisms through which arsenic exerts its neuro-and hepatotoxicity in humans.",
Arsenic,1352763,"SPECTROSCOPIC STUDIES IN MEAN AMPLITUDES OF VIBRATION OF PENTAFLUORIDES OF ARSENIC, PHOSPHORUS AND VANADIUM Abstract: ",
Arsenic,1519168,"Characterization by chemical analysis of Portuguese baroque polychrome wooden scupltures with erudite and popular features Abstract: Making use of several analytical techniques, four erudite and four popular Portuguese baroque wooden sculptures were studied. The materials and techniques employed were identified and the relationship between their artistic quality and the materials used was investigated. In general, the pigments were common at the time, but one pigment discovered in the beginning of the 18th century and two rare arsenic pigments were also identified. In popular sculptures cost-saving was detected, particularly concerning the gold leaf. Regarding some technical procedures identified, recommendations found in historical documents did not seem to have been entirely followed, neither in erudite nor in popular sculptures.",
Arsenic,734908,"Arsenic exposure perturbs epithelial-mesenchymal cell transition and gene expression in a collagen gel assay Abstract: Arsenic is a naturally occurring metalloid and environmental contaminant. Arsenic exposure in drinking water is reported to cause cancer of the liver, kidneys, lung, bladder, and skin as well as birth defects, including neural tube, facial, and vasculogenic defects. The early embryonic period most sensitive to arsenic includes a variety of cellular processes. One key cellular process is epithelial-mesenchymal transition (EMT) where epithelial sheets develop into three-dimensional structures. An embryonic prototype of EMT is found in the atrioventricular (AV) canal of the developing heart, where endothelia differentiate to form heart valves. Effects of arsenic on this cellular process were examined by collagen gel invasion assay (EMT assay) using explanted AV canals from chicken embryo hearts. AV canals treated with 12.5-500 ppb arsenic showed a loss of mesenchyme at 12.5 ppb, and mesenchyme formation was completely inhibited at 500 ppb. Altered gene expression in arsenic-treated explants was investigated by microarray analysis. Genes whose expression was altered consistently at exposure levels of 10, 25, and 100 ppb were identified, and results showed that 25 ppb in vitro was particularly effective. Three hundred and eighty two genes were significantly altered at this exposure level. Cytoscape analysis of the microarray data using the chicken interactome identified four clusters of altered genes based on published relationships and pathways. This analysis identified cytoskeleton and cell adhesion-related genes whose disruption is consistent with an altered ability to undergo EMT. These studies show that EMT is sensitive to arsenic and that an interactome-based approach can be useful in identifying targets.",
Arsenic,1032073,"Methods for testing interactions, with applications to occupational exposures, smoking, and lung cancer Abstract: Various approaches to assessing the interaction between smoking and occupational exposures are described. The definition of interaction depends on the measure of association under consideration and can be expressed in terms of disease risk, time, or dose. Simple descriptive methods and maximum likelihood model fitting methods are presented for analyzing interactions in terms of joint effects on disease risk. Methods for assessing the influence of exposures on times to disease, using appropriate denominators, are also described. The various approaches are illustrated with published data on lung cancer in relation to asbestos, radon daughters, chloromethyl ethers, and arsenic. Some of the mechanisms that can be invoked to explain the observed patterns include initiation and promotion, lung clearance, transport across cell membranes, and mucous secretion.",
Arsenic,1797755,"Impact of volcanic plume emissions on rain water chemistry during the January 2010 Nyamuragira eruptive event: implications for essential potable water resources Abstract: On January 2, 2010 the Nyamuragira volcano erupted lava fountains extending up to 300 m vertically along an ~1.5 km segment of its southern flank cascading ash and gas on nearby villages and cities along the western side of the rift valley. Because rain water is the only available potable water resource within this region, volcanic impacts on drinking water constitutes a major potential hazard to public health within the region. During the 2010 eruption, concerns were expressed by local inhabitants about water quality and feelings of physical discomfort (e.g. nausea, bloating, indigestion, etc.) after consuming rain water collected after the eruption began. We present the elemental and ionic chemistry of drinking water samples collected within the region on the third day of the eruption (January 5, 2010). We identify a significant impact on water quality associated with the eruption including lower pH (i.e. acidification) and increases in acidic halogens (e.g. F(-) and Cl(-)), major ions (e.g. SO(4)(2-), NH(4)(+), Na(+), Ca(2+)), potentially toxic metals (e.g. Al(3+), Mn(2+), Cd(2+), Pb(2+), Hf(4+)), and particulate load. In many cases, the water's composition significantly exceeds World Health Organization (WHO) drinking water standards. The degree of pollution depends upon: (1) ash plume direction and (2) ash plume density. The potential negative health impacts are a function of the water's pH, which regulates the elements and their chemical form that are released into drinking water.",
Arsenic,1508689,"16(th) IHIW: Anti-HLA alloantibodies of the of IgA isotype in re-transplant candidates Abstract: In this multicentre study, sera from 803 retransplant candidates, including 775 kidney transplant recipients, were analysed with regard to the presence and specificity of anti-HLA alloantibodies of the IgA isotype using a modified microsphere-based platform. Of the kidney recipients, nearly one-third (n = 237, 31%) had IgA alloantibodies. Mostly, these antibodies were found in sera that also harboured IgG alloantibodies that could be found in a total of 572 (74%) of patients. Interestingly, IgA anti-HLA antibodies were preferentially targeting HLA class I antigens in contrast to those of the IgG isotype, which targeted mostly both HLA class I and II antigens. Donor specificity of the IgA alloantibodies could be established for over half of the 237 patients with IgA alloantibodies (n = 124, 52%). A further 58 patients had specificities against HLA-C or HLA-DP, for which no information regarding donor typing was available. In summary, these data showed in a large cohort of retransplant candidates that IgA alloantibodies occur in about one-third of patients, about half of these antibodies being donor specific.",
Arsenic,2343433,"Influences on domestic well water testing behavior in a Central Maine area with frequent groundwater arsenic occurrence Abstract: In 2001 the Environmental Protection Agency (EPA) adopted a new standard for arsenic (As) in drinking water of 10?g/L, replacing the old standard of 50?g/L. However, for the 12% of the U.S. population relying on unregulated domestic well water, including half of the population of Maine, it is solely the well owner's responsibility to test and treat the water. A mailed household survey was implemented in January 2013 in 13 towns of Central Maine with the goal of understanding the population's testing and treatment practices and the key behavior influencing factors in an area with high well-water dependency and frequent natural groundwater As. The response rate was 58.3%; 525 of 900 likely-delivered surveys to randomly selected addresses were completed. Although 78% of the households reported that their well has been tested, half of it was more than 5years ago. Among the 58.7% who believe they have tested for As, most do not remember the results. Better educated, higher income homeowners who more recently purchased their homes are most likely to have included As when last testing. While households agree that water and As-related health risks can be severe, they feel low personal vulnerability and there are low testing norms overall. Significant predictors of including As when last testing include: having knowledge that years of exposure increases As-related health risks (risk knowledge), knowing who to contact to test well water (action knowledge), believing that regular testing does not take too much time (instrumental attitude), and having neighbors who regularly test their water (descriptive norm). Homeowners in As-affected communities have the tendency to underestimate their As risks compared to their neighbors. The reasons for this optimistic bias require further study, but low testing behaviors in this area may be due to the influence of a combination of norm, ability, and attitude factors and barriers.",
Arsenic,2279333,"Reversibility of changes in brain cholinergic receptors and acetylcholinesterase activity in rats following early life arsenic exposure Abstract: In view of the increasing incidences of arsenic induced health effects and the vulnerability of the developing brain to its toxic effects, studies have been carried out to investigate the mechanism of arsenic induced cholinergic alterations and understand if such changes are persistent or transient on withdrawal of arsenic exposure. Male rats were exposed to arsenic (2mg/kg or 4mg/kg body weight, p.o) from post-lactational day (PD)22 to PD59, and the effect on selected behavioral and neurochemical end points associated with cholinergic functions was assessed on PD60 and PD90. Decrease in the binding of muscarinic-cholinergic receptors in frontal cortex (26%, 43%) and hippocampus (21%, 34%) associated with reduced CHRM2 mRNA levels, acetylcholinesterase activity and expression of ChAT and PKC ?-1 was observed in arsenic exposed rats on PD60 as compared to controls. Spatial learning and memory and muscle strength were affected following arsenic exposure in rats on PD60 and associated with arsenic induced cholinergic alterations. Enhanced oxidative stress associated with increased expression of pro-apoptotic proteins and decreased expression of anti-apoptotic proteins was distinct in both frontal cortex and hippocampus following arsenic exposure in rats on PD60. The cholinergic alterations and other neurochemical modifications were found to be linked with increased arsenic levels in frontal cortex (1.39, 3.90-fold) and hippocampus (3.23, 5.48-fold) on PD60. Although a trend of recovery was observed both in behavioral and neurochemical endpoints on withdrawal of arsenic exposure on PD90, the results indicate that continuous arsenic exposure may have detrimental effects.",
Arsenic,1251006,"Draft genome of halomonas species strain GFAJ-1 (ATCC BAA-2256) Abstract: Halomonas strain GFAJ-1 was reported in Science magazine to be a remarkable microbe for which there was “arsenate in macromolecules that normally contain phosphate, most notably nucleic acids.” The draft genome of the bacterium was determined (NCBI accession numbers AHBC01000001 through AHBC01000103). It appears to be a typical gamma proteobacterium.",
Arsenic,1349104,"METAL CONCENTRATIONS IN TISSUES OF AMERICAN LOBSTERS (HOMARUS AMERICANUS, MILNE-EDWARDS) WITH EPIZOOTIC SHELL DISEASE Abstract: ",
Arsenic,1349747,"Distribution of arsenic in MSMA-treated lodgepole pines infested by the mountain pine beetle, Dendroctonus ponderosae (Coleoptera: scolytidae), and its relationship to beetle mortality Abstract: The LC50 of MSMA (monosodium methanearsonate) for first- and second-instar mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, mining for 4 d in ground phloem tissue impregnated with methane arsonic acid (CH3AsO3H2), the pure form of arsenic in MSMA, was 102 ppm. Application of MSMA 3 wk after attack to axe-frills (cuts) near the root collar of five lodgepole pines, Pinus contorta var. latifolia Engelmann, resulted in high accumulations of arsenic in phloem and sapwood near the point of application and in foliage 11 wk later. MPB taken from bolts cut from MSMA-treated trees 1 m above the axe-frill were all dead. There was a strong relationship between amounts of arsenic in MPB and those in phloem tissue up to 2 m. At sampling points above 2 m on treated trees, arsenic residues in phloem and sapwood were, on average, not significantly different from those occurring naturally in tissues of lodgepole pine. Enough arsenic could have passed through the tissues to kill or inhibit the brood MPB within the trees, but MPB mortality was probably due to an interaction of many factors including moisture deficit and fungal invasion of the host tree.",
Arsenic,1027379,"Arsenic exposure in pregnancy: a population-based study in Matlab, Bangladesh Abstract: This study assessed the exposure of pregnant women to arsenic in Matlab, Bangladesh, an area with highly-elevated concentrations of arsenic in tubewells, by measuring concentrations of arsenic in urine. In a defined administrative area, all new pregnancies were identified by urine test in gestational week 6-8, and women were asked to participate in the assessment of arsenic exposure. Urine for analysis of arsenic was collected immediately and in gestational week 30. In total, 3,426 pregnant women provided urine samples during January 2002-March 2003. There was a considerable variation in urinary concentrations of arsenic (total range 1-1,470 microg/L, adjusted to specific gravity 1.012 g/mL), with an overall median concentration of 80 microg/L (25th and 75th percentiles were 37 and 208 microg/L respectively). Similar concentrations were found in gestational week 30, indicating no trend of decreasing exposure, despite the initiation of mitigation activities in the area. Arsenic exposure was negatively associated with socioeconomic classes and achieved educational level. There were marked geographical variations in exposure. The results emphasize the urgent need for efficient mitigation activities and investigations of arsenic-related reproductive effects.",
Arsenic,1025593,"Reduction in urinary arsenic levels in response to arsenic mitigation efforts in Araihazar, Bangladesh Abstract: BACKGROUND: There is a need to identify and evaluate an effective mitigation program for arsenic exposure from drinking water in Bangladesh. OBJECTIVE: We evaluated the effectiveness of a multifaceted mitigation program to reduce As exposure among 11,746 individuals in a prospective cohort study initiated in 2000 in Araihazar, Bangladesh, by interviewing participants and measuring changes in urinary As levels. METHODS: The interventions included a) person-to-person reporting of well test results and health education; b) well labeling and village-level health education; and c) installations of 50 deep, low-As community wells in villages with the highest As exposure. RESULTS: Two years after these interventions, 58% of the 6,512 participants with unsafe wells (As ?50 ?g) at baseline had responded by switching to other wells. Well labeling and village-level health education was positively related to switching to safe wells (As < 50 ?g/L) among participants with unsafe wells [rate ratio (RR) = 1.84; 95% confidence interval (CI), 1.60-2.11] and inversely related to any well switching among those with safe wells (RR = 0.80; 95% CI, 0.66-0.98). The urinary As level in participants who switched to a well identified as safe (<50 ?g As/L) dropped from an average of 375 ?g As/g creatinine to 200 ?g As/g creatinine, a 46% reduction toward the average urinary As content of 136 microg As/g creatinine for participants that used safe wells throughout. Urinary As reduction was positively related to educational attainment, body mass index, never-smoking, absence of skin lesions, and time since switching (p for trend < 0.05). CONCLUSIONS: Our study shows that testing of wells and informing households of the consequences of As exposure, combined with installation of deep community wells where most needed, can effectively address the continuing public health emergency from arsenic in drinking water in Bangladesh.",
Arsenic,1337665,"Environmental arsenic exposure and DNA methylation of the tumor suppressor gene p16 and the DNA repair gene MLH1: Effect of arsenic metabolism and genotype Abstract: Arsenic is carcinogenic, possibly partly through epigenetic mechanisms. We evaluated the effects of arsenic exposure and metabolism on DNA methylation. Arsenic exposure and methylation efficiency in 202 women in the Argentinean Andes were assessed from concentrations of arsenic metabolites in urine (inorganic arsenic, methylarsonic acid [MMA], and dimethylarsinic acid [DMA]), measured by HPLC-ICPMS. Methylation of CpGs of the tumor suppressor gene p16, the DNA repair gene MLH1, and the repetitive elements LINE1 was measured by PCR pyrosequencing of blood DNA. Genotyping (N = 172) for AS3MT was performed using Sequenom™, and gene expression (N = 90) using Illumina DirectHyb HumanHT-12 v3.0. Median arsenic concentration in urine was 230 ?g L(-1) (range 10.1-1251). In linear regression analysis, log(2)-transformed urinary arsenic concentrations were positively associated with methylation of p16 (? = 0.14, P = 0.0028) and MLH1 (? = 0.28, P = 0.0011), but not with LINE1. Arsenic concentrations were of borderline significance negatively correlated with expression of p16 (r(s) = -0.20; P = 0.066)), but not with MLH1. The fraction of inorganic arsenic was positively (? = 0.026; P = 0.010) and DMA was negatively (? = -0.017, P = 0.043) associated with p16 methylation with no effect of MMA. Carriers of the slow-metabolizing AS3MT haplotype were associated with more p16 methylation (P = 0.022). Arsenic exposure was correlated with increased methylation, in blood, of genes encoding enzymes that suppress carcinogenesis, and the arsenic metabolism efficiency modified the degree of epigenetic alterations.",
Arsenic,1339162,"Arsenite transporters expression in rice (Oryza sativa L.) associated with arbuscular mycorrhizal fungi (AMF) colonization under different levels of arsenite stress Abstract: As a silicon hyperaccumulator, lowland rice takes up higher levels of As than many other plants due to silicic acid and arsenite sharing the same transporters (Lsi1 and Lsi2). Glomus intraradices (AH01) was inoculated to rice under different arsenite concentrations (0, 2 and 8 ?M) in order to investigate the interactions between arbuscular mycorrhizal fungus and rice on the accumulation of arsenite. The relative mRNA expressions of Lsi1 and Lsi2 resulted in a down-regulating trend in mycorrhizal plants. Under 2 ?M arsenite treatments, Lsi1 and Lsi2 were significantly decreased, by 0.7-fold (P<0.05) and 0.5-fold (P<0.01), respectively, in mycorrhizal plants when compared with non-mycorrhizal plants. This led to the decrease of arsenite uptake per unit of root dry mass. No organic As species were detected in both roots and shoots. The As(III)/As(V) ratios indicated that mycorrhizal plants immobilized most of the arsenite proportion in the roots and prevented its translocation from the roots to the shoots.",
Arsenic,1019367,"Does arsenic exposure increase the risk for circulatory disease? Abstract: Studies of residents in communities with high endemic concentrations of arsenic in drinking water suggest a deleterious effect on the circulatory system; however, studies among workers with high occupational exposures generally have shown either no or weak associations. This discrepancy could be a result of the healthy worker effect, including the healthy hire component and the healthy worker survivor effect (HWSE). Therefore, the authors conducted analyses of arsenic exposure in relation to circulatory disease mortality among 2,802 Tacoma, Washington, smelter workers by using 1) internal comparisons to control for the healthy hire effect and 2) the lagging method, adjustment for employment status, and the G-null test to control for the HWSE. Both lagging and adjustment for work status increased circulatory mortality rate ratios at all exposure levels, as compared with a baseline Poisson model. This excess mortality was limited to cardiovascular disease; no excess was observed for cerebrovascular disease. G-null analyses suggested no adverse effect, but power was very limited for this analysis. Overall, these results may indicate that the HWSE obscures an effect of arsenic on circulatory disease. Since cardiovascular deaths constitute about one-third of total mortality, small rate ratios translate into large numbers of excess deaths and, if causal, could be of wide public health significance. Further studies of arsenic exposure and cardiovascular disease are needed, and those conducted in occupational cohorts must control for the HWSE.",
Arsenic,710835,"Arsenic intoxication, a hemorheologic view Abstract: Arsenic (As) is a toxic semi-metal of wide distribution in nature. People living in regions where drinking water contains large quantities of arsenic, have an unusually high likelihood of developing blood-vessel diseases, but little is known about the mechanisms involved, i.e. the blood rheologic alterations that would contribute to the circulatory obstruction. Erythrocytes are the main target cells for arsenic compounds systemically absorbed and their cell membrane is the first place against the toxic. In this paper we have examined the in vitro effect of arsenic (As(V)) on the rheologic properties of human erythrocytes in relation with membrane fluidity and internal microviscosity. According to our present results, As(V) treatment produces oxidative degradation of membrane lipids and alteration of internal microviscosity. These red blood cells (RBCs) membrane and cytoplasmic structural damage consequently alters RBCs rheologic properties: an alteration of the RBCs discoid shape to stomatocytes, a diminution of erythrocyte deformability and an enhancement of osmotic fragility and cell aggregability. These effects impaired blood fluid behaviour that contribute to obstruct peripheral circulation and provides anemia, both clinic evidences typical of arsenic cronic intoxication.",
Arsenic,1337288,"Association between arsenic suppression of adipogenesis and induction of CHOP10 via the endoplasmic reticulum stress response Abstract: Background: There is growing evidence that chronic exposure to inorganic arsenic (iAs) is associated with an increased prevalence of type 2 diabetes (T2D). However, the mechanisms for the diabetogenic effect of iAs are still largely unknown. White adipose tissue (WAT) actively stores and releases energy and maintains lipid and glucose homeostasis. Objective: We sought to determine the mechanisms of arsenic suppression of adipogenesis. Methods: The effects and associated mechanisms of iAs and its major metabolites on adipogenesis were determined in 3T3-L1 preadipocytes, mouse adipose-derived stromal-vascular fraction cells (ADSVFCs), and human adipose tissue–derived stem cells (ADSCs). Results: Exposure of 3T3-L1 preadipocytes to noncytotoxic levels of arsenic, including inorganic arsenite (iAs3+, ? 5 ?M), inorganic arsenate (? 20 ?M), trivalent monomethylated arsenic (MMA3+, ? 1 ?M), and trivalent dimethylated arsenic (DMA3+, ? 2 ?M) decreased adipogenic hormone-induced adipogenesis in a concentration-dependent manner. In addition, iAs3+, MMA3+, and DMA3+ exhibited a strong inhibitory effect on adipogenesis in primary cultured mouse ADSVFCs and human ADSCs. Time-course studies in 3T3-L1 cells revealed that inhibition of adipogenesis by arsenic occurred in the early stage of terminal adipogenic differentiation and was highly correlated with the induction of C/EBP homologous protein (CHOP10), an endoplasmic reticulum (ER) stress response protein. Induction of CHOP10 by arsenic is associated with reduced DNA-binding activity of CCAAT/enhancer-binding protein ? (C/EBP?), which regulates the transcription of peroxisome proliferator-activated receptor ? and C/EBP?. Conclusions: Low-level iAs and MMA3+ trigger the ER stress response and up-regulate CHOP10, which inhibits C/EBP? transcriptional activity, thus suppressing adipogenesis. Arsenic-induced dysfunctional adipogenesis may be associated with a reduced capacity of WAT to store lipids and with insulin resistance.",
Arsenic,1015791,"Classification accuracy and cut point?selection Abstract: In biomedical research and practice, quantitative tests or biomarkers are often used for diagnostic or screening purposes, with a cut point established on the quantitative measurement to aid binary classification. This paper introduces an alternative to the traditional methods based on the Youden index and the closest-to-(0, 1) criterion for threshold selection. A concordance probability evaluating the classification accuracy of a dichotomized measure is defined as an objective function of the possible cut point. A nonparametric approach is used to search for the optimal cut point maximizing the objective function. The procedure is shown to perform well in a simulation study. Using data from a real-world study of arsenic-induced skin lesions, we apply the method to a measure of blood arsenic levels, selecting a cut point to be used as a warning threshold. Copyright © 2012 John Wiley &amp; Sons, Ltd.",
Arsenic,1597410,"Measurement of arsenic relative bioavailability in swine Abstract: This study describes a method for measuring the relative oral bioavailability (RBA) of arsenic (As) in soil and other soil-like media using young swine as the animal model. Groups of animals are exposed to site soil or sodium arsenate orally for 12 d. Forty-eight-hour urine samples were collected from each animal on d 6-7, 8-9, and 10-11 and were analyzed for total As. The urinary excretion fraction (UEF) for each group was estimated by plotting the mass of As excreted in urine by each animal as a function of the dose administered, and then fitting a linear model to the data using simultaneous weighted linear regression. The RBA of a test material is calculated as the ratio of the UEF value for the test material divided by the UEF of the reference material. Uncertainty around the RBA estimate is calculated using Fieller's theorem. Application of this method to a series of test soils indicates that RBA values for As can range from 18 to 52%. This wide variability supports the conclusion that there may be important differences in RBA between sites, and that use of a site-specific RBA value is likely to increase the accuracy of risk estimates for exposure to As in soil.",
Arsenic,1030445,"Clastogenic effects of inorganic arsenic salts on human chromosomes in vitro Abstract: Arsenic is well documented as a paradoxical human carcinogen. In West Bengal, several million people were found to be arsenic affected who were exposed to this metalloid principally through drinking water. The arsenic-contaminated drinking water contains both trivalent as well as pentavalent arsenic. In this study, the comparative in vitro cytogenetic effects of two inorganic salts of arsenic, trivalent sodium arsenite (NaAsO(2)) and pentavalent sodium arsenate (Na(2)HAsO4) in three different concentrations, were screened for damage to chromosome and cell division following exposure to human lymphocyte culture. The chromosome-breaking activities in cultured lymphocytes were significantly higher for the compounds with trivalent (NaAsO(2)) than with pentavalent arsenic (Na(2)HAsO(4)), as reflected by the higher chromosomal aberration percentage in the similar doses used. It suggests that sodium arsenite was considerably more clastogenic than sodium arsenate. Moreover, increases in chromosomal aberrations were proportional with the increased dose of exposure for both trivalent and pentavalent forms of arsenic.",
Arsenic,1519006,"Optimization of chemical and instrumental parameters in hydride generation laser-induced breakdown spectrometry for the determination of arsenic, antimony, lead and germanium in aqueous samples Abstract: A laser induced breakdown spectrometry hyphenated with on-line continuous flow hydride generation sample introduction system, HG-LIBS, has been used for the determination of arsenic, antimony, lead and germanium in aqueous environments. Optimum chemical and instrumental parameters governing chemical hydride generation, laser plasma formation and detection were investigated for each element under argon and nitrogen atmosphere. Arsenic, antimony and germanium have presented strong enhancement in signal strength under argon atmosphere while lead has shown no sensitivity to ambient gas type. Detection limits of 1.1mgL(-1), 1.0mgL(-1), 1.3mgL(-1) and 0.2mgL(-1) were obtained for As, Sb, Pb and Ge, respectively. Up to 77 times enhancement in detection limit of Pb were obtained, compared to the result obtained from the direct analysis of liquids by LIBS. Applicability of the technique to real water samples was tested through spiking experiments and recoveries higher than 80% were obtained. Results demonstrate that, HG-LIBS approach is suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring in aqueous environments.",
Arsenic,2343573,"Identifying sources and controlling factors of arsenic release in saline groundwater aquifers Abstract: An integrated hydrogeochemical study was carried out to realize the occurrence of arsenic (As) in a saline aquifer. Saline groundwater was mostly concentrated in the uppermost aquifer, and non-saline water was in the lower aquifer in the study area. High As concentrations were found in both the uppermost and lower aquifers. No correlation among salinity, well depth and As concentration was observed. Various forms of Fe oxyhydroxides were identified in the magnetic fractions, which were concentrated by high gradient magnetic separation (HGMS) technique, revealing that the redox cycling of Fe occurred in the subsurface. High levels of Fe, HCO3-, DOC and NH4+ concentrations accompanying alkaline pH in the As-rich groundwater were consistent with the mechanism triggered by the microbially mediated reductive dissolution of Fe oxyhydroxides. A proposed threshold value of 50 mu gL(-1) As concentration was used as an indicator for identification of active proceeding reductive dissolution of As-bearing Fe oxyhydroxides in the saline aquifer. Desorption behaviors of As were relevant to its valence in the sediments and the co-existence of anions. Experimental and numerical results showed that additions of Cl- and SO42-, which represent the main anions of saline water, had minor effect on leaching sedimentary As. Although bicarbonate addition resulted in less As desorption than that of phosphate on a molar basis, the contribution of bicarbonate to the total release of As was greater than phosphate due to the much higher concentration of bicarbonate in shallow groundwater and the associated microbial mediation. Collectively, the chemical effect of saline water on the As release to groundwater is mild in the coastal aquifer.",
Arsenic,2149123,"Expression and prognostic value of Ars2 in hepatocellular carcinoma Abstract: <strong>BACKGROUND: </strong>Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in China. Arsenic resistance protein 2 (Asr2) was reported to be important for microRNA (miR) biogenesis, and its depletion could reduce the levels of several miRs, including miR-21, which is over-expressed in HCC. We hypothesized that Ars2 is also overexpressed in HCC and may be involved in the biological properties of HCC.<br /><br /><strong>METHODS: </strong>Ars2 immunolabeling was evaluated in 132 HCCs. Ars2 immunolabeling, Ars2 qRT-PCR and miR-21 were evaluated in 20 HCCs and in paired normal tissues. Ars2 shRNA was transfected into SMCC-7721 and HepG2 HCC cells. The cell proliferation and expression of Ars2 and miR-21 were subsequently evaluated.<br /><br /><strong>RESULTS: </strong>Ars2 was expressed primarily in the nucleus of HCC cells. The expression of Ars2 was statistically correlated with the loss of HCC differentiation and pathological stage. The survival rates of patients with low Ars2 expression in HCC were statistically higher than patients with overexpressed Ars2 in HCC. Ars2 and miR-21 were more highly expressed in HCC specimens than normal tissues, and they were also correlated. The knockdown of Ars2 in HCC cells inhibited miR-21 expression and cell proliferation.<br /><br /><strong>CONCLUSIONS: </strong>Ars2 is overexpressed in HCC and may have prognostic value; it might play an important role in HCC proliferation and miR-21 expression.",
Arsenic,1351826,"Groundwater arsenic concentrations in Vietnam controlled by sediment age Abstract: Arsenic contamination of groundwater continues to threaten the health of millions of people in southeast Asia. The oxidation of organic carbon, coupled to the reductive dissolution of arsenic-bearing iron oxides, is thought to control the release of sediment-bound arsenic into groundwater. However, the cause of the high spatial variability in groundwater arsenic concentrations—which can range from 5 to 500??g?l?1 within distances of a few kilometres—has been uncertain. Here, we combine measurements of sediment age, organic-matter reactivity and water chemistry at four locations along a cross-section of the arsenic-contaminated Red River floodplain in Vietnam to determine the origin of variations in groundwater arsenic concentrations. The burial age of the aquifer sediments, determined using optical stimulated luminescence, ranged from 460 years near the course of the present-day river to 5,900 years at the margin of the floodplain. The groundwater arsenic content and the reactivity of sedimentary organic carbon, determined using radiotracer measurements of the rate of methanogenesis, declined with sediment age. The sedimentary pools of both iron and arsenic also declined with the burial age of the sediments. We suggest that the age of aquifer sediments is a key determinant of groundwater arsenic concentrations.",
Arsenic,1340254,"Purification and characterization of carboxymethyl cellulase and protease by Ulocladium botrytis Preuss ATCC 18042 using water hyacinth as a substrate under solid state fermentation Abstract: The potential of 12 fungal strains to produce carboxymethyl cellulase (CMCase) and protease on Eichhornia crassipes (water hyacinth) wastes was investigated under conditions of solid state fermentation. Ulocladium botrytis (Preuss) was selected as the best fungus for the production of both enzymes. The best nitrogen sources for production of CMCase and protease were yeast extract and malt extract, respectively. CMCase and protease were purified by isopropanol (1:1) precipitation and column chromatography on Sephadex G-100 and DEAE-cellulose. Purification fold of 47.34 and 51.78, with 852.11 and 1,469.38 U/mg specific activity was achieved with 40.3 and 56.25% recovery after purification of CMCase and protease, respectively. The purified CMCase expressed its maximal activity at 60°C and pH 5.2, showed good stability in the pH range of 5.2–5.4 and its midpoint of thermal inactivation (Tm) was 60°C after 75 min exposure. The purified protease expressed its maximal activity at 35°C and pH 5.2, showed good stability in the pH range of 5.6–6.0 and its midpoint of thermal inactivation (Tm) was 35°C after 75 min exposure. The best substrate concentration for CMCase was 1.2% (w/v) Na-CMC and for protease, it was 0.8% (w/v) casein. The best enzyme concentration for the two tested enzymes was 0.4 U/ml. Ions of Ca2+, Na+ and K+ showed a stimulatory effect but sodium arsenate and iodoacetate showed an inhibitory effect. Moreover, Ag2+ and Hg2+ inhibited both enzyme activities completely. The purified enzymes from Ulocladium botrytis had molecular weights of 50 and 83 kDa for CMCase, and 47 kDa for protease on SDS-PAGE.",
Arsenic,1024131,"Status of groundwater arsenic contamination and human suffering in a Gram Panchayet (cluster of villages) in Murshidabad, one of the nine arsenic affected districts in West Bengal, India Abstract: A detailed study was carried out in a cluster of villages known as Sagarpara Gram Panchayet (GP), covering an area of 20 km2 and population of 24,419 to determine the status of groundwater arsenic contamination and related health effects. The arsenic analysis of all hand tubewells (n = 565) in working condition showed, 86.2% and 58.8% of them had arsenic above 10, and 50 microgl(-1), respectively. The groundwater samples from all 21 villages in Sagarpara GP contained arsenic above 50 microgl(-1). In our preliminary clinical survey across the 21 villages, 3,302 villagers were examined and 679 among them (20.6%) were registered with arsenical skin lesions. A total of 850 biological samples (hair, nail and urine) were analysed from the affected villages and, on average, 85% of them contained arsenic above the normal level. Thus, many people of Sagarpara might be sub-clinically affected. Our data was compared with the international one to estimate population in Sagarpara GP at risk from arsenical skin lesions and cancer. Proper watershed management and economical utilization of available surface water resources along with the villagers' participation is urgently required to combat the present arsenic crisis.",
Arsenic,599800,"DOSE-DEPENDENT UPTAKE, ELIMINATION, AND TOXICITY OF MONOSODIUM METHANEARSONATE IN ADULT ZEBRA FINCHES (TAENIOPYGIA GUTTATA) Abstract: Monosodium methanearsonate (MSMA), an arsenic-based pesticide, has been used for the past 10 years in attempts to suppress mountain pine beetle (Dendroctonus ponderosae) outbreaks in British Columbia, Canada. Previous studies have shown that cavity nesting forest birds such as woodpeckers forage and breed in MSMA treated pine stands. Here we examined the effects of MSMA in the laboratory using the zebra finch (Taeniopygia guttata), with the objective to examine tissue distribution and sublethal toxic effects in a model avian species. Zebra finches were exposed to this pesticide at doses similar to those found in bark beetle samples from MSMA stands of trees treated in the southern interior of British Columbia (8, 24, and 72 ÃŽÂ¼g/g/d and a control group). Results showed high excretion (>90%) of arsenic in all dose groups, as well as dose-dependent trends in accumulation of arsenic in the blood (p < 0.001) and specific tissues. Monomethylarsonic acid, MMA (V), was the predominant form of arsenic in the blood plasma. Dimethylarsinic acid was the major form of arsenic found in the liver (83%) and kidney (61%) tissues. The brain tissue contained primarily the MMA (V) form (57%). Significant weight loss occurred in the two highest dose groups (p < 0.05). Birds in the highest dose group lost up to 15% of initial body mass. ABSTRACT FROM AUTHOR Copyright of Environmental Toxicology & Chemistry is the property of Allen Press Publishing Services Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1936144,"The function of digestive enzymes on Cu, Zn, and Pb release from soil in in vitro digestion tests Abstract: The bioaccessibility of soil heavy metals is the solubility of soil heavy metals in synthetic human digestive juice, which is usually determined using in vitro digestion test. To reveal the effects of digestive enzymes on soil heavy metals bioaccessibility, three representative in vitro digestion tests, Simple Bioaccessibility Extraction Test (SBET), Physiologically Based Extraction Test (PBET), and Simple Gastrointestinal Extraction Test (SGET), were chosen. The bioaccessibility of soil Cu, Zn, and Pb in each method were respectively evaluated with and without digestive enzymes, and the differences were compared. The results showed that the effects of digestive enzymes varied with different methods and elements. Because of digestive enzymes addition, the environmental change from acid gastric phase to neutral intestinal phase of PBET did not result in apparently decrease of the bioaccessibility of soil Cu. However, the solubility of soil Zn and Pb were pH-dependent. For SGET, when digestive enzymes were added, its results reflected more variations resulting from soil and element types. The impacts of digestive enzymes on heavy metal dissolution are mostly seen in the intestinal phase. Therefore, digestive enzyme addition is indispensable to the gastrointestinal digestion methods (PBET and SGET), while the pepsin addition is not important for the methods only comprised of gastric digestion (SBET).",
Arsenic,1022097,"Manganese exposure from drinking water and children's academic achievement Abstract: Drinking water manganese (WMn) is a potential threat to children's health due to its associations with a wide range of outcomes including cognitive, behavioral and neuropsychological effects. Although adverse effects of Mn on cognitive function of the children indicate possible impact on their academic achievement little evidence on this issue is available. Moreover, little is known regarding potential interactions between exposure to Mn and other metals, especially water arsenic (WAs). In Araihazar, a rural area of Bangladesh, we conducted a cross-sectional study of 840 children to investigate associations between WMn and WAs and academic achievement in mathematics and languages among elementary school-children, aged 8-11 years. Data on As and Mn exposure were collected from the participants at the baseline of an ongoing longitudinal study of school-based educational intervention. Annual scores of the study children in languages (Bangla and English) and mathematics were obtained from the academic achievement records of the elementary schools. WMn above the WHO standard of 400?g/L was associated with 6.4% score loss (95% CI=-12.3 to -0.5) in mathematics achievement test scores, adjusted for WAs and other sociodemographic variables. We did not find any statistically significant associations between WMn and academic achievement in either language. Neither WAs nor urinary As was significantly related to any of the three academic achievement scores. Our finding suggests that a large number of children in rural Bangladesh may experience deficits in mathematics due to high concentrations of Mn exposure in drinking water.",
Arsenic,735016,"Effects of MEK and DNMT inhibitors on arsenic-treated human uroepithelial cells in relation to Cyclin-D1 and p16 Abstract: Arsenic compounds are well-known toxic and carcinogenic agents, and they are widely distributed throughout the earth's crust. These compounds are associated with various human malignancies. It has been reported that there is an elevated risk of bladder cancer in an area highly contaminated with arsenic on the southwest coast of Taiwan. However, the underlying mechanisms of arsenic-associated carcinogenesis are still unclear. The cell cycle regulatory proteins are important indicators in control of cell cycle progression. Moreover, the high expression of Cyclin-D1 and loss of p16 has been associated with a worse prognosis in a variety of human cancers. Therefore, we investigated the effect of arsenic on Cyclin-D1 and p16 expression and evaluated the role of the ERK signaling pathway and DNA methylation in arsenic carcinogenesis. Our study results showed that Cyclin-D1 high expression was found in 56.3% (9/16) of urothelial carcinomas (UC) from a blackfoot disease (BFD) area and 6.3% (1/16) of UC from a non-BFD area (p=0.002). The p16 low expression in 81.2% (13/16) of UC from BFD areas was significantly lower than in non-BFD areas (25.0%; 4/16) (p=0.001). In addition, the Cyclin-D1 increased expression but decreased p16 expression in arsenite-treated SV-HUC-1 cells. However, when cells were pretreated with inhibitors (5-aza-CdR or U0126), the effects of arsenite on Cyclin-D1 and p16 expression were suppressed. Finally, these results indicated that Cyclin-D1 and p16 both might play important roles in carcinogenesis as a result of arsenic.",
Arsenic,2347664,"Single-nucleotide polymorphism-based noninvasive prenatal screening in a high-risk and low-risk cohort Abstract: <strong>OBJECTIVE: </strong>To estimate performance of a single-nucleotide polymorphism-based noninvasive prenatal screen for fetal aneuploidy in high-risk and low-risk populations on single venopuncture.<br /><br /><strong>METHODS: </strong>One thousand sixty-four maternal blood samples from 7 weeks of gestation and beyond were included; 1,051 were within specifications and 518 (49.3%) were low risk. Cell-free DNA was amplified, sequenced, and analyzed using the Next-generation Aneuploidy Test Using SNPs algorithm. Samples were called as trisomies 21, 18, 13, or monosomy X, or euploid, and male or female.<br /><br /><strong>RESULTS: </strong>Nine hundred sixty-six samples (91.9%) successfully generated a cell-free DNA result. Among these, sensitivity was 100% for trisomy 21 (58/58, confidence interval [CI] 93.8-100%), trisomy 13 (12/12, CI 73.5-100%), and fetal sex (358/358 female, CI 99.0-100%; 418/418 male, CI 99.1-100%), 96.0% for trisomy 18 (24/25, CI 79.7-99.9%), and 90% for monosomy X (9/10, CI 55.5-99.8%). Specificity for trisomies 21 and 13 was 100% (905/905, CI 99.6-100%; and 953/953, CI 99.6-100%, respectively) and for trisomy 18 and monosomy X was 99.9% (938/939, CI 99.4-100%; and 953/954, CI 99.4-100%, respectively). However, 16% (20/125) of aneuploid samples did not return a result; 50% (10/20) had a fetal fraction below the 1.5th percentile of euploid pregnancies. Aneuploidy rate was significantly higher in these samples (P&lt;.001, odds ratio 9.2, CI 4.4-19.0). Sensitivity and specificity did not differ in low-risk and high-risk populations.<br /><br /><strong>CONCLUSIONS: </strong>This noninvasive prenatal screen performed with high sensitivity and specificity in high-risk and low-risk cohorts. Aneuploid samples were significantly more likely to not return a result; the number of aneuploidy samples was especially increased among samples with low fetal fraction. This underscores the importance of redraws or, in rare cases, invasive procedures based on low fetal fraction.<br /><br /><strong>LEVEL OF EVIDENCE: </strong>: II.",
Arsenic,871561,"Vascular leakage induced by exposure to arsenic via increased production of NO, hydroxyl radical and peroxynitrite Abstract: Previous studies have shown that in situ exposure to arsenic induced increased vascular leakage. However, the underlying mechanism remains unclear. Reactive nitrogen and oxygen species such as nitric oxide (NO) and hydroxyl radical (OH(-)) are known to affect vascular permeability. Therefore, the goal of our present studies is to investigate the functional impact of the generation of NO or OH(-) on arsenic-induced vascular leakage. Vascular permeability changes were evaluated by means of Evans blue (EB) assay. Rats were anesthetized and intravenously injected with EB. Permeability changes were induced in back skin by intradermal injections of sodium arsenite mixed with NOS inhibitor: N(omega)-Nitro-L-arginine methyl ester (L-NAME) or aminoguanidine (AG) and OH(-) scavenger: 1,3 Dimethyl-2 thiourea (DMTU). Experiments were also performed to determine whether DMTU mixed with L-NAME would further inhibit arsenic-induced vascular leakage as compared with attenuation effects by either DMTU or L-NAME. One hour after administration, EB accumulated in the skin was extracted and quantified. Both L-NAME (0.02, 0.1 and 0.5 micromol/site) and DMTU (0.05, 0.2 and 1.2 micromol/site) inhibited the increase in vascular leakage induced by arsenite. However, only high dose (1 micromol/site) of AG significantly attenuated arsenite-induced vascular leakage. In contrast, neither D-NAME (0.02, 0.1 and 0.5 micromol/site) nor AG (0.04 and 0.2 micromol/site) attenuated increased vascular leakage by arsenic. DMTU mixed with L-NAME caused no further inhibition of arsenic-induced vascular leakage by either DMTU or L-NAME. The techniques of India ink and immunostaining were used to demonstrate both vascular labeling and nitrotyrosine staining in tissue treated with arsenic. L-NAME apparently reduced the density of leaky vessels and the levels of peroxynitrite staining induced by arsenite. These results suggest that NO, OH(-) and peroxynitrite play a role in increased vascular permeability induced by arsenic exposure.",
Arsenic,1508662,"Preparation and characterization of a novel magnetic biochar for arsenic removal Abstract: A magnetic biochar based adsorbent with colloidal or nanosized ?-Fe(2)O(3) particles embedded in porous biochar matrix was fabricated via thermal pyrolysis of FeCl(3) treated biomass. The synthesized samples were studied systematically by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, selected-area electron diffraction pattern, scanning electron microscopy, energy-dispersive X-ray analysis, superconducting quantum interference device, and batch sorption measurements. The characterization analyses showed that large quantity of ?-Fe(2)O(3) particles with size between hundreds of nanometers and several micrometers tightly grow within the porous biochar matrix. Biochar/?-Fe(2)O(3) composite exhibited excellent ferromagnetic property with a saturation magnetization of 69.2emu/g. Batch sorption experimental results showed that the composite has strong sorption ability to aqueous arsenic. Because of its excellent ferromagnetic properties, the arsenic-laden biochar/?-Fe(2)O(3) composite could be easily separated from the solution by a magnet at the end of the sorption experiment.",
Arsenic,1519068,"Fish micronucleus assay to assess genotoxic potential of arsenic at its guideline exposure in aquatic environment Abstract: The exposure to arsenic, a potential genotoxic carcinogen in humans, via drinking water is a serious worldwide health hazard. The arsenic content of 10 ?g L(-1) in drinking water, however, has been established as its guideline standard (maximum contaminant limit) that has been estimated to pose minimum risk to cancer. Since micronucleus induction in the erythrocytes of fish is a sensitive indicator of genotoxic agents in water, the piscine micronucleus assay was used in the present experiment to assess the genotoxic potential of arsenic at its various exposure levels including the guideline value for drinking water. The experiments were conducted in two different species of fishes, the pond murrel (Channa punctatus) and the goldfish (Carassius auratus). Significant increases in the frequency of micronucleated erythrocytes were documented in a dose-dependent manner in both Channa and Carassius. The fishes, however, exhibited variations in inter-specific sensitivity to micronucleus induction following arsenic exposure. The exposure level of arsenic at its guideline value for drinking water, therefore, exhibited marked genotoxicity in fishes.",
Arsenic,628024,"Amelioration of sodium arsenite-induced clastogenicity by tea extracts in Chinese hamster v79 cells Abstract: Since the early 1980s, an alarming problem of groundwater arsenic (As) contamination has devastated many districts of West Bengal in India. People drinking As-contaminated water have been suffering severe health problems such as hyperkeratosis, blackfoot disease, neuropathy, and cancer of various sites. DNA damage and genetic instability induced by the inorganic arsenicals present in water are thought to be prerequisites for the initiation of carcinogenesis. Many natural polyphenols, which are consumed through our daily diet, possess excellent cancer chemopreventive properties. Tea, a popular beverage worldwide and rich in polyphenols, has exhibited many health benefits. The present study was conducted to examine the anticlastogenic action of tea extracts (both green and black) against the As-induced chromosomal aberrations. We also evaluated the role of tea in inducing antioxidant enzymes such as superoxide dismutase and catalase to provide protection against the oxidative stress induced by As. Our results demonstrated that tea extracts, particularly Darjeeling tea extract, are effective in counteracting the clastogenicity (chromatid breaks, in particular) of the most potent form of As, sodium arsenite. The antioxidant function of tea in reducing clastogenicity may be partly due to the induction of phase II detoxification enymes, such as superoxide dismutase and catalase. Our results suggest that the use of tea may be an effective approach in combating the health crisis generated by As.",
Arsenic,2337200,"Urethrography Interpretation Skills of Urology and Radiology Residents at Tertiary Care Medical Centers Abstract: <strong>OBJECTIVE: </strong>To assess the ability of urology and radiology residents to interpret retrograde urethrograms (RUGs) and voiding cystourethrograms (VCUGs).<br /><br /><strong>METHODS: </strong>A standardized examination of 10 combination RUGs and VCUGs of the male urethra was administered to urology and radiology residents from all levels of training at Washington University, Stanford University, and Northwestern University. Residents were asked to evaluate stricture location(s) and length, if present.<br /><br /><strong>RESULTS: </strong>Sixty residents participated, consisting of 26 from Washington University, 15 from Stanford University, and 19 from Northwestern University. Average years of training for urology and radiology were 3.6 and 2.8 years, respectively (P = .01). Normal RUGs and VCUGs were recognized by 18 of 31 radiologists (58%) and 19 of 29 urologists (65.5%; P = .5). Anterior strictures were correctly identified in 145 of 403 (36%) and 165 of 377 (43.8%) responses by radiologists and urologists, respectively (P = .03). Posterior strictures were correctly identified in 20 of 62 (32.3%) and 10 of 58 (17.2%) responses by radiologists and urologists, respectively (P = .09). When both groups of residents were combined, anterior strictures were identified correctly more often than posterior strictures (39.7% vs 25%; P &lt;.01). Overall accuracy was 24.2% (75 of 310) for the radiology group and 27.9% (81 of 290) for the urology group (P = .30). In the presence of multiple strictures, accuracy declined to 7.26% (9 of 124) for the radiology group and 9.48% (11 of 116) for the urology group (P = .5), with a combined accuracy of 8.33% (20 of 240).<br /><br /><strong>CONCLUSION: </strong>Radiology and urology residents in the United States have poor skills at interpreting urethrography, especially when multiple strictures or posterior strictures are present. A formal educational program for RUG and VCUG interpretation should be designed and implemented into the radiology and urology resident curriculum.",
Arsenic,1252587,"DNA single-strand breaks in L-132 cells resulting from inhibition of repair polymerization shortly after exposure to dimethylarsinic acid Abstract: DNA single-strand breaks due to the inhibition of repair polymerization in cultured human pulmonary epithelial (L-132) cells after exposure to dimethylarsinic acid (DMAA), a main metabolite of inorganic arsenics in mammals, were examined. The strand breaks were detected by an alkaline elution method with the use of inhibitors of DNA polymerase, aphidicolin (aph) and 2',3'-dideoxythymidine (ddT); the former inhibits DNA polymerases alpha, delta and epsilon, and the latter inhibits DNA polymerase beta. Generally, DNA polymerases delta and epsilon are thought to be associated with necleotide excision (long patch) repair and polymerase beta with base excision (short patch) repair. After exposure of the L-132 cells to 10 mM DMAA, the breaks occurred in a time-dependent manner during incubation for 1-6 h under the inhibition of aph-sensitive polymerases with 50 micrograms/ml aph plus 10 mM hydroxyurea (HU) for the last 1 h of the DMAA exposure. Also, when DNA polymerase beta was inhibited with 10 mM ddT plus 1 microM methotrexate (MTX), the exposure of L-132 cells to 10 mM DMAA for 6 h significantly induced DNA single-strand breaks. An experiment of the co-treatment with both aph and ddT suggested that in the DNA repair process, aph-sensitive polymerases, probably polymerases delta and/or epsilon, and polymerase beta, functioned independently on different lesions induced after exposure to DMAA.",
Arsenic,1030498,"Elevated human telomerase reverse transcriptase gene expression in blood cells associated with chronic arsenic exposure in Inner Mongolia, China Abstract: <strong>BACKGROUND: </strong>Arsenic exposure is associated with human cancer. Telomerase-containing human telomerase reverse transcriptase (hTERT) can extend telomeres of chromosomes, delay senescence, and promote cell proliferation leading to tumorigenesis.<br /><br /><strong>OBJECTIVE: </strong>The goal of this study was to investigate the effects of As on hTERT mRNA expression in humans and in vitro.<br /><br /><strong>METHOD: </strong>A total of 324 Inner Mongolia residents who have been exposed to As via drinking water participated in this study. Water and toenail samples were collected and analyzed for As. Blood samples were quantified for hTERT mRNA expression using real-time polymerase chain reaction. The hTERT mRNA levels were linked to water and nail As concentrations and skin hyperkeratosis. Human epidermal keratinocytes were treated with arsenite to assess effects on cell viability and hTERT expression in vitro.<br /><br /><strong>RESULTS: </strong>hTERT mRNA expression levels were significantly associated with As concentrations of water (p&lt;0.0001) and nails (p=0.002) and also associated with severity of skin hyperkeratosis (p&lt;0.05), adjusting for age, sex, smoking, and pesticide use. Females showed a higher slope than males (females: 0.126, p=0.0005; males: 0.079, p=0.017). In addition to water and nail As concentrations, age (p&lt;0.0001) and pesticide use (p=0.025) also showed significant associations with hTERT expression. The hTERT expression levels decreased with age. Tobacco smoking did not affect hTERT expression (p=0.13). hTERT expression was significantly correlated with OGG1 and ERCC1 expression. The in vitro results also showed a dose-response relationship between arsenite concentrations and hTERT expression and reached the peak at 1 microM.<br /><br /><strong>CONCLUSIONS: </strong>hTERT expression was associated with As exposure in vivo and in vitro. The increased hTERT expression may be a cellular response to genomic insults by As and may also indicate that As may function as a tumor promoter in carcinogenesis in humans.",
Arsenic,1373195,"Accumulation of arsenic by Rhaphidophyceae Chattonella antiqua (Hada) Ono Abstract: BIOSIS COPYRIGHT: BIOL ABS. Rhaphydophyceae Chattonella antiqua (Hada) Ono was grown in seawater containing an arsenic concentration up to 50 mg dm-3, and survived even at 200 mg dm-3. The arsenic content increased with an increase of the surrounding arsenic, iron and manganese concentrations. However, arsenic accumulation was unaffected by phosphorus concentration. Also, arsenic content in C. antiqua decreased at a selenium concentration of up 20 mg dm-3, and was reduced by the addition of antimony. In the living cells, about 52% of the arsenic which accumulated in each cell was found in the intracellular fraction, 27% in the lipid fraction, and 21% in the cell wall fraction.",
Arsenic,1597390,"Assessment of Arsenite, Arsenate, and Chromate Phytotoxicity Based on the Activity of Seed Germination and Growth (Root & Shoot) of Various Plant Seeds Abstract: ",
Arsenic,1017704,"Identification of arsenite-and arsenic diglutathione-binding proteins in human hepatocarcinoma cells Abstract: It is generally accepted that trivalent arsenicals are more toxic than the corresponding pentavalent arsenicals, since trivalent arsenicals bind the thiol groups of biomolecules, leading to a deterioration in cellular functions. In the present study, we prepared three different arsenic-bound sepharoses and investigated the binding of hepatic cytosolic proteins to pentavalent, trivalent, and glutathione-conjugated trivalent arsenicals. SDS-PAGE showed no proteins bound to pentavalent arsenic specifically. In contrast, we found a number of proteins that have specific and high affinity for trivalent arsenic. Two of those proteins were identified: protein disulfide isomerase-related protein 5 (PDSIRP5) and peroxiredoxin 1/enhancer protein (PRX1/EP). These proteins have vicinal cysteines, as previously reported. In contrast, one of the prominent proteins that did not bind to trivalent arsenic was identified as calreticulin precursor. Although there are 3 cysteines in calreticulin precursor, two of the cysteines are spaced more than 25 amino acids apart. Five synthetic peptides containing 2 vicinal cysteines were prepared to study whether they would inhibit the binding of PDSIRP5, PRX1/EP, and other arsenic-binding proteins to trivalent arsenicals. Only two of the five peptides effectively inhibited binding, suggesting that other amino acids besides the 2 vicinal cysteines may modulate the affinity of cysteine-rich proteins for trivalent arsenicals. We further investigated hepatic cytosolic proteins that bound specifically to glutathione-conjugated trivalent arsenic, which is the most abundant form of arsenical in bile fluid. Four proteins that bound specifically to glutathione-conjugated trivalent arsenic were identified; interestingly, these proteins were different from the trivalent arsenic-binding proteins. These results suggest that although glutathione-conjugation is an important process in the metabolism, excretion, and detoxification of arsenicals, glutathione-conjugated arsenicals can still react with some proteins in hepatic cells.",
Arsenic,1936177,"Procedia Earth and Plantetary Science Arsenite oxidizing bacterium isolated from high arsenic groundwater aquifers from Datong Basin, Northern China Abstract: ",
Arsenic,1597319,"Modulation of antioxidant defense system after long term arsenic exposure in Zantedeschia aethiopica and Anemopsis californica Abstract: Zantedeschia aethiopica (calla lily) and Anemopsis californica (yerba mansa) are plant species capable of accumulating arsenic (As) and therefore proposed as phytoremediation for removal of As from drinking water. The effects of a continuous 6 month As exposure (34±11?g/L) from local contaminated groundwater on the antioxidant response of Z. aethiopica and A. californica were evaluated in leaves and stems of the plants bimonthly in a subsurface flow constructed wetland. As increased the activities of the antioxidant enzymes ascorbate peroxidase, glutathione reductase and catalase where higher levels were observed in Z. aethiopica than A. californica. No significant differences were detected on lipid peroxidation levels or antioxidant capacity evaluated by ORAC and DPPH assays or total phenol contents in any part of the plant, although in general the leaves of both plants showed the best antioxidant defense against the metal. In conclusion, Z. aethiopica and A. californica were able to cope to As through induction of a more sensitive enzymatic antioxidant response mechanism.",
Arsenic,627989,"The effects of arsenic compounds on human and bovine lymphocyte mitogenesis in vitro Abstract: The response of human and bovine peripheral blood lymphocytes to PHA stimulation was measured in the presence of low concentrations of sodium arsenite and sodium arsenate. In bovine lymphocytes, 41% augmentation of the response occurred at 10?6 Image arsenite with a return to the normal response at 2.5 × 10?6 Image . Complete inhibition of mitogenesis occurred at 6 × 10?6 Image . In the presence of sodium arsenate, similar results were obtained but at the higher concentrations of 2 × 10?5 (for 57% augmentation), 5.2 × 10?5, and 1.9 × 10?4 Image , respectively. The possible significance of these findings in view of the known relationship between chronic arsenicalism and human skin cancer is discussed. It is suggested that arsenic compounds may, by potentiating mitogenesis, increase the possibility of errors in DNA replication, some of which could be potentially carcinogenic. Additionally, interference with the immune response could enable potentially cancerous cells to escape immune surveillance.",
Arsenic,1018482,"Effect of arsenic (V) on the antioxidant defense system: in vitro oxidation of rat plasma lipoprotein Abstract: Adult male rats were treated orally with sodium arsenate (10 mg As/kd/day) for 2 days, and in increase in hepatic glutathione level was seen. Ascorbic acid content increased in both liver and plasma of intoxicated animals. Hepatic activities of superoxide dismutase and glutathione peroxidase did not change with the treatment and there was no increase in the level of lipid peroxidation measured as thiobarbituric acid-reacting substances (TBARS). Arsenic decreased the plasma level of uric acid and increased the plasma triglycerides content without modifying vitamin E levels. Both total lipoproteins and very low density lipoprotein plus low density lipoprotein (VLDL + LDL) fractions demonstrated greater propensity for in vitro oxidation than the corresponding untreated rats. The last finding might be a useful parameter for determining the degree of oxidative stress in the initial steps of intoxication with arsenic.",
Arsenic,2345809,"Constraints on precipitation of the ferrous arsenite solid H7Fe4(AsO3)5 Abstract: Formation of Fe(II)-As(III) solids is suspected to limit dissolved As concentrations in anaerobic environments. Iron(II) precipitates enriched in As(III) have been observed after microbial reduction of As(V)-loaded lepidocrocite (gamma-FeOOH) and symplesite (Fe(II)(3)(As(V)O-4)(2)]center dot 8H(2)O) and upon abiotic reaction of Fe(II) with As(III). However, the conditions favorable for Fe(II)-As(III) precipitation and the long-term stability (relative to dissolution) of this phase are unknown. Here we examine the composition, local structure, and solubility of an Fe(II)-As(III) precipitate to determine environments where such a solid may form and persist. We reveal that the Fe(II)-As(III) precipitate has a composition of H7Fe4(AsO3)(5) and a log K-50 of 34 for the dissolution reaction defined as: H7Fe4(AsO3)(5) +8H(+) = 4Fe(2+) + 5H(3)AsO(3). Extended X-ray absorption fine structure spectroscopic analysis of H7Fe4(AsO3)(5) shows that the molecular environment of Fe is dominated by edge-sharing octahedra within an Fe(OH)(2) sheet and that As is dominated by corner-sharing (AsO3)-O-III pyramids, which are consistent with previously published structures of As(III)-rich Fe(II) solids. The H7Fe4(AsO3)(5) solid has a pH-dependent solubility and requires millimolar concentrations of dissolved Fe(II) and As(III) to precipitate at pH &lt;7.5. By contrast, alkaline conditions are more conducive to formation of H7Fe4(AsO3)(5); however, a high concentration of Fe(II) is required, which is unusual under alkaline conditions.",
Arsenic,628805,"Prevalence of arsenic exposure from drinking water and awareness of its health risks in a Bangladeshi population: Results from a large population-based study Abstract: We conducted a population-based prevalence survey in Araihazar, Bangladesh, to describe the distribution of arsenic exposure in a rural Bangladeshi population and to assess the population's awareness to this problem as well as to possible remediation options. Water samples from 5,967 contiguous tube wells in a defined geographic area were tested using laboratory-based methods. Additionally, for each well, the owner/caretaker (or a close relative) was interviewed regarding his or her awareness of the health consequences of As exposure. Arsenic exposure data and demographic characteristics for the 65,876 users of these wells were also collected from the 5,967 respondents. Among the 65,876 residents, more than half (54%) regularly consumed well water with an As concentration > or = 50 microg/L--above the acceptable government standard in Bangladesh. Respondents were 15-92 years of age, with an average age of 42 years, and 43% were male. Presence of awareness was significantly related to male sex, nonlabor head of household occupation, better housing, and having had the well tested for As concentration. Most respondents (92%) expressed a willingness to take steps to reduce their exposure, with switching to a safe well the most favored option (46.2%). Willingness to reduce exposure was positively related to awareness of the health risks of As. However, the association between awareness and switching to a safe well [odds ratio (OR) = 1.25; 95% confidence interval (CI), 1.01-1.54] was no stronger than the associations between awareness and using surface water (with or without treatments) (OR = 1.54; 95% CI, 1.22-1.95) or using an existing well after treatment or increasing the depth (OR = 1.34; 95% CI, 1.08-1.67). These findings suggest that health education programs may need to target individuals with lower socioeconomic status and that well switching should be encouraged with more appropriate health education. Increasing knowledge of the health consequences of As may be an important element in facilitating remediation.",
Arsenic,1348358,"Putative P-glycoprotein expression in arsenite-resistant Leishmania donovani down-regulated by verapamil Abstract: Western immunoblots of whole cell lysate and crude membrane extract of an in vitro selected sodium m-arsenite-resistant L. donovani strain revealed a 230-kDa protein identified by an anti-P-glycoprotein (Pgp) antibody. Immunofluorescence microscopy, using the same antibody, detected putative Pgp on resistant parasites. Overexpression of the putative Pgp was down-regulated by verapamil. These results provided, possibly, the first evidence that (i) overexpression of Pgp-like protein occurs in arsenite-resistant Leishmania that are cross-resistant to structurally and functionally unrelated drugs and (ii) verapamil regulates drug sensitivity possibly by down-regulating Pgp expression in the arsenite-resistant Leishmania.",
Arsenic,1508569,"Monitoring of arsenic levels in some ready-to-use anti-malaria herbal products from drug sales outlets in the Madina area of Accra, Ghana Abstract: In Ghana anti-malaria herbal medicines or products are used to compliment commercial drugs in treatment and prevention of Plasmodium falciparum infections. In this study, four common aqueous based anti-malaria herbal products (coded HEB, KFE, MDM and NIB) which are used by Ghanaian population from pharmacy/herbal stores in the Madina area, Accra were blindly and randomly sampled for cadmium (Cd), arsenic (As) and Lead (Pb) analysis using Atomic Absorption Spectrophotometry technique. Arsenic concentrations were 1.087?g/mL (108.7%), 1.027?g/mL (102.7%), 0.330?g/mL (33.0%) and 0.274?g/mL (27.4%) in MDM, KFE, NIB and HEB respectively. Arsenic concentration determined in MDM and KFE were above the maximum permissible limit of 1.0ppm determined by WHO/FAO. Cadmium concentration in each of the four products was below the detection limit (&lt;0.002mg/mL). Lead concentration in KFE, NIB, and HEB were also below the detection limit (&lt;0.005mg/mL). The maximum permissible limits for Pb and Cd determined by WHO/FAO are 10.0ppm and 0.3ppm respectively. Thus, random assessment on the safety of some ready-to-use aqueous based anti-malaria herbal products on the market is necessary to prevent public health hazards associated with consuming these plant extracts. Although lead concentration in the anti-malaria herbal products were below the maximum concentration limits, their cumulative effect on the health of individuals which consume about four/five bottles for effective malaria parasite clearance cannot be ignored.",
Arsenic,2149340,"Metals and Related Substances in Drinking Water: Proceedings of the 4th International Conference, Meteau Relation between arsenic in drinking water and carcinoma of urinary bladder: Data from Municipality of Zrenjanin Abstract: ",
Arsenic,1337334,"Evaluation of gene expression changes in human primary uroepithelial cells following 24-Hr exposures to inorganic arsenic and its methylated metabolites Abstract: Gene expression changes in primary human uroepithelial cells exposed to arsenite and its methylated metabolites were evaluated to identify cell signaling pathway perturbations potentially associated with bladder carcinogenicity. Cells were treated with mixtures of inorganic arsenic and its pentavalent or trivalent metabolites for 24 hr at total arsenic concentrations ranging from 0.06 ?M to 18 ?M. One series (five samples) was conducted with arsenite and pentavalent metabolites and a second (10 samples) with arsenite and trivalent metabolites. Similar gene expression responses were obtained for pentavalent or trivalent metabolites. A suite of eight gene changes was consistently identified across individuals that reflect effects on key signaling pathways: oxidative stress, protein folding, growth regulation, metallothionine regulation, DNA damage sensing, thioredoxin regulation, and immune response. No statistical significance of trend (NOSTASOT) analysis of these common genes identified lowest observed effect levels (LOELs) from 0.6 to 6.0 ?M total arsenic and no observed effect levels (NOELs) from 0.18 to 1.8 ?M total arsenic. For the trivalent arsenical mixture, benchmark doses (BMDs) ranged from 0.13 to 0.92 ?M total arsenic; benchmark dose lower 95% confidence limits (BMDLs) ranged from 0.09 to 0.58 ?M total arsenic. BMDs ranged from 0.53 to 2.7 ?M and BMDLs from 0.35 to 1.7 ?M for the pentavalent arsenical mixture. Both endpoints varied by a factor of 3 across individuals. Thisstudy is the first to examine gene expression response in primary uroepithelial cells from multiple individuals and to identify no effect levels for arsenical-induced cell signaling perturbations in normal human cells exposed to a biologically plausible concentration range. © Environ. Mol. Mutagen., 2012. © 2012 Wiley Periodicals, Inc.",
Arsenic,1353323,ARSENIC SEDIMENTATION ALONG THE SLOPE OF A LAKE BASIN Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM MACROPHYTE CONTROL WETLAND VEGETATION MICHIGAN USA,
Arsenic,1704078,"Expression of DcHsp17.7, a small heat shock protein gene in carrot (Daucus carota L.) Abstract: We examined the expression pattern of the small heat shock protein (sHSP) gene, DcHsp17.7, under various conditions. In non-stressed leaf tissue, DcHsp17.7 was absent or present at very low levels; however, exposure to an elevated temperature (40A degrees C, 4 hours) led to an accumulation of this protein. Furthermore, after cessation of heat stress, the levels were sustained for two days, but diminished entirely thereafter. The persistence of DcHsp17.7 in post-heat-shocked leaves suggests that this sHSP may play a role during recovery after heat stress. Overnight heat stress (40A degrees C, from 9 pm to 9 am) induced a higher level of DcHsp17.7, compared with that of plants exposed to heat stress during the day (40A degrees C, from 9 am to 9 pm). These observations indicate that DcHsp17.7 gene expression is influenced by circadian rhythm. The levels of the DcHsp17.7 transcripts and their encoded protein increased after exposure to exogenous abscisic acid (ABA) and salicylic acid (SA), suggesting that these plant growth hormones may be involved in the expression of the DcHsp17.7 gene. Additionally, exposure to heavy metals, such as lead (Pb) and arsenic (As), led to increased levels of DcHsp17.7 transcripts and protein.",
Arsenic,2064130,Optimization of Process Parameters for Removal of Arsenic Using Activated Carbon-Based Iron-Containing Adsorbents by Response Surface Methodology Abstract: ,
Arsenic,2064262,"Neuroglobin involvement in the course of arsenic toxicity in rat cerebellar granule neurons Abstract: Exposure to arsenic in drinking water results in a widespread environmental problem in the world, and the brain is a major target. Neuroglobin is a vertebrate heme protein regarded as playing neuroprotective role in hypoxia or oxidative stress. In this study, we investigated the toxic effects of sodium arsenite (NaAsO2) on primary cultured rat cerebellar granule neurons (CGNs) and detected neuroglobin (Ngb) expression in rat CGNs exposed to NaAsO2. Our results show that apoptosis was obviously induced by NaAsO2 treatment in rat CGNs by annexin V-fluorescein isothiocyanate assay. Intracellular reactive oxygen species generation increased significantly in the cells exposed to NaAsO2, and the apoptotic effects could be partially reversed by antioxidant N-acetyl-L-cysteine. Ngb protein and mRNA expression were significantly downregulated in rat CGNs shortly after NaAsO2 exposure and then upregulated after a longer time of exposure. Furthermore, mRNA expression changed more than protein expression and the toxic effect of NaAsO2 on Ngb expression is dose dependent. Higher Ngb expression was also detected in rat cerebellum, but not in other parts (cerebrum, hippocampus, and midbrain) of the brain exposed to NaAsO2 for 16 weeks. Taken together, cytotoxic effects of NaAsO2 on rat CGNs is induced at least partly by oxidative stress and Ngb may influence the course of arsenic toxicity in rat CGNs and rat cerebellum.",
Arsenic,1070431,"Concomitant induction of heme oxygenase-1 attenuates the cytotoxicity of arsenic species from lumbricus extract in human liver HepG2 cells Abstract: Heme oxygenase-1 (HO-1) is an inducible antioxidant enzyme that degrades heme to three products, biliverdin, carbon monoxide (CO), and iron ion. The present study was originally designed to characterize the HO-1 induction by Lumbricus extract as a potential cytoprotective mechanism. Through bioactivity-guided fractionation, with human HepG2 cells as the cellular detector, surprisingly, we found that arsenic was enriched in the active fractions isolated from Lumbricus extract. Arsenic speciation was further carried out by liquid chromatography with inductively coupled plasma mass spectrometry (LC/ICP-MS). Our results showed that Lumbricus extract contained two major arsenic species, arsenite (As(III) ; 53.7%) and arsenate (As(V) ; 34.2%), and six minor arsenic species. Commercial sodium arsenite (NaAsO(2) ) was used to verify the effects of Lumbricus extract on HO-1 expression and related intracellular signaling pathways. Both p38 MAP kinase and NF-E2-related factor 2 (Nrf2) pathways were found to modulate HO-1 induction by Lumbricus extract and NaAsO(2) . The cytotoxicity of arsenite was augmented by p38 MAP kinase inhibitor SB202190 and HO-1 inhibitor tin protoporphyrin IX (SnPP), whereas p38 MAP kinase inhibitor SB202190 also inhibited HO-1 induction by NaAsO(2) . These results suggest that arsenic-containing compounds are responsible for HO-1 induction by Lumbricus extract. Although the exact role of toxic arsenic compounds in the treatment of oxidative injury remains unclear, concomitant HO-1 induction may be a key mechanism to antagonize the cytotoxicity of arsenic compounds in human cells.",
Arsenic,2279201,"Enrichment, distribution and sources of heavy metals in the sediments of Deception Bay, Queensland, Australia Abstract: Sediment samples from 13 sampling sites in Deception Bay, Australia were analysed for the presence of heavy metals. Enrichment factors, modified contamination indices and Nemerow pollution indices were calculated for each sampling site to determine sediment quality. The results indicate significant pollution of most sites by lead (average enrichment factor (EF) of 13), but there is also enrichment of arsenic (average EF 2.3), zinc (average EF 2.7) and other heavy metals. The modified degree of contamination indices (average 1.0) suggests that there is little contamination. By contrast, the Nemerow pollution index (average 5.8) suggests that Deception Bay is heavily contaminated. Cluster analysis was undertaken to identify groups of elements. Strong correlation between some elements and two distinct clusters of sampling sites based on sediment type was evident. These results have implications for pollution in complex marine environments where there is significant influx of sand and sediment into an estuarine environment.",
Arsenic,1255637,"Impact of sampling frequency on mean concentrations and estimated loads of suspended sediment in a Norwegian river: Implications for water management Abstract: Reliable estimates of mean concentrations and loads of pollutants in rivers have become increasingly important for management purposes, particularly with the implementation of the European Union Water Framework Directive (WFD). Here, the Numedalslågen River (5500km(2)) in southern Norway was used as a case study to evaluate the effects of sampling frequency on mean concentrations and estimated loads of suspended particulate matter (SPM). Daily monitoring data from five seasons (April/June-October/November 2001-2005) were analyzed, and three different load estimation techniques were tested: rating curves, linear interpolation, and the ratio method. The reliability of mean SPM concentrations improved with increasing sampling frequency, but even weekly sampling gave error rates as high as 70% in seasons with elevated sediment loads. Load estimates varied considerably depending on both the sampling frequency and the calculation method used. None of the methods provided consistently good results, but the lowest error rate was achieved when using the rating curve on data from fortnightly sampling and additional sampling during floods. Sampling at monthly intervals gave the highest error rates and cannot be recommended for any of the calculation methods applied here. SPM concentrations were correlated (r(2)&gt;0.5) with arsenic, lead, nickel, orthophosphate, and total phosphorus in the Numedalslågen River. Therefore, the current findings may also have implications for substances other than SPM. The discussion considers examples from actual use of infrequently collected data, and it is advised that managers account for uncertainties in both concentration means and load estimates when assessing the state of a water body or planning mitigation measures.",
Arsenic,628328,"Oxidative DNA damage following exposure to dimethylarsinous iodide: The formation of cis-thymine glycol Abstract: The purpose of the present study was to elucidate the genotoxic mechanism of trivalent dimethylated arsenic, particularly the induction mechanism of oxidative stress in nuclear bases. Cis-thymine glycol was used as a biomarker of DNA oxidation damage. The treatment of thymine with dimethylarsinous iodide (DMI), a model compound of dimethylarsinous acid, induced the formation of cis-thymine glycol. This oxidative damage was induced via the production of dimethylated arsenic peroxide, but not via the production of superoxide anion or hydrogen peroxide. Trivalent dimethylated arsenic may thus play an important role in arsenic carcinogenesis through the induction of oxidative base damage.",
Arsenic,656850,"A Mechanistic Approach for Modulation of Arsenic Toxicity in Human Lymphocytes by Curcumin, an Active Constituent of Medicinal Herb Curcuma longa Linn Abstract: Chronic exposure of humans to high concentrations of arsenic in drinking water is associated with skin lesions, peripheral vascular disease, hypertension, blackfoot disease and a high risk of cancer. Arsenic induces single strand breaks, DNA-protein crosslinks and apurinic sites in DNA, which are prerequisites for induction of cancer. Amelioration of such damages with natural compounds could be an effective strategy to combat arsenic toxicity. Curcumin is the active ingredient of turmeric, a common household spice, which is a rich source of polyphenols and this compound has been extensively studied as a chemopreventive agent against many types of cancer. The present study investigates whether curcumin could counteract the DNA damage caused by arsenic as assessed by single cell gel electrophoresis (SCGE) using peripheral blood lymphocytes, from healthy donors. It was observed that DNA damage induced by arsenic could be efficiently reduced by curcumin and the effect was more pronounced when lymphocytes were pre-incubated with curcumin prior to arsenic insult. Arsenic caused DNA damage by generation of reactive oxygen species (ROS) and enhancement of lipid peroxidation levels. Curcumin counteracted the damage by quenching ROS, decreasing the level of lipid peroxidation and increasing the level of phase II detoxification enzymes like catalase, superoxide dismutase and glutathione peroxidase. Curcumin also enhanced the DNA repair activity against arsenic induced damage. The expression of polymerase, a repair enzyme, was found to be highly elevated when arsenite induced damaged cells were allowed to repair in presence of curcumin. Results indicate that curcumin has significant role in confronting the deleterious effect caused by arsenic, which could be an economic mode of arsenic mitigation among rural population in West Bengal, India.",
Arsenic,627336,"Differential oxidation of thioredoxin-1, thioredoxin-2, and glutathione by metal ions Abstract: Metal toxicity often includes the generation of reactive oxygen species (ROS) and subsequent oxidative stress, but whether metals have different effects on the major thiol antioxidant systems is unknown. Here, we examine the effects of arsenic, cadmium, cesium, copper, iron, mercury, nickel, and zinc on glutathione (GSH), cytoplasmic thioredoxin-1 (Trx1), and mitochondrial thioredoxin-2 (Trx2) redox states. GSH/GSSG redox states were determined by HPLC, and Trx1 and Trx2 redox states were determined by Redox Western blot methods. Copper, iron, and nickel showed significant oxidation of GSH but relatively little oxidation of either Trx1 or Trx2. Arsenic, cadmium, and mercury showed little oxidation of GSH but significantly oxidized both Trx1 and Trx2. The magnitude of effects of arsenic, cadmium, and mercury was greater for the mitochondrial Trx2 (>60 mV) compared to the cytoplasmic Trx1 (20 to 40 mV). Apoptosis signal-regulating kinase 1 (ASK1) may be activated by two different pathways, one dependent upon GSH and glutaredoxin and the other independent of GSH and dependent upon thioredoxin. ASK1 activation and cell death were observed with metals that oxidized thioredoxins but not with metals that oxidized GSH. These findings show that metals have differential oxidative effects on the major thiol antioxidant systems and that activation of apoptosis may be associated with metal ions that oxidize thioredoxin and activate ASK1. The differential oxidation of the major thiol antioxidant systems by metal ions suggest that the distinct thiol/disulfide redox couples represented by GSH/GSSG and the thioredoxins may convey different levels of control in apoptotic and toxic signaling pathways.",
Arsenic,2088373,The arsenolysis reaction in the biotechnological synthesis of ribavirin. The in vitro and in vivo inhibition of influenza A virus replication with a combination of ribavirin and ozeltamivir Abstract: ,
Arsenic,1354191,DETERMINATION OF ARSENIC AND ANTIMONY IN 85 GEOCHEMICAL REFERENCE SAMPLES BY AUTOMATED HYDRIDE GENERATION AND ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY Abstract: ,
Arsenic,1797791,"The protective role of resveratrol in the sodium arsenite-induced oxidative damage via modulation of intracellular GSH homeostasis Abstract: Sodium arsenite (NaAsO2) is a well-established environmental carcinogen that has been found to cause various human malignant tumors. Thus, how to prevent the deleterious effects caused by NaAsO2 has received widely concerns. Resveratrol (3,4',5-trihydroxystilbene), a polyphenol found in numerous plant species, has recently been known as a natural and powerful antioxidant. However, whether resveratrol could attenuate the toxicity of NaAsO2 and its detailed mechanisms have not been reported. In this study, the protective effects of resveratrol against NaAsO2-induced oxidative and genetic damage as well as apoptosis were evaluated for the first time. We demonstrated that cotreatment of human bronchial epithelial cell with 5 ?M resveratrol for 24 h effectively reduced the levels of 30 ?M NaAsO2-induced reactive oxygen species, chromosomal and DNA damage, and cell apoptosis. Revseratrol was also showed to significantly elevate the concentration of glutathione (GSH) and the activities of its relevant enzymes as compared with NaAsO2 alone, indicating that resveratrol ameliorates the toxicity of NaAsO2 by modulating the process of GSH biosynthesis, recycling and utilization. Our findings further suggest that GSH homeostasis represents one of the detoxification mechanisms responding to NaAsO2 exposure, and resveratrol plays a protective role in the regulation of oxidative and genetic damage as well as apoptosis through the modulation of GSH homeostasis.",
Arsenic,514936,"Heat shock protein 60 (HSP60) response of Plationus patulus (Rotifera: Monogononta) to combined exposures of arsenic and heavy metals Abstract: Organisms produce stress proteins as a response to natural and anthropogenic environmental changes. Induction of stress proteins has been reported in a variety of aquatic organisms, including rotifers, exposed to pollutants. Past studies on stress protein responses of rotifers have focused on exposure to single toxicants. In this study the rotifer Plationus patulus was exposed singly and in combination to various concentrations of As, Cr, Cu, Ni, Ph, and Zn. Following exposure, total protein was quantified (Bradford method) and stress protein 60 (HSP60) was identified using Western blotting. P. patulus induced HSP60 as a response to single exposures to Cr, Cu, Ni, Pb and Zn. HSP60 expression was increased (2 fold) in rotifers exposed to these single elements at both low and high concentrations as compared to unexposed rotifers. Arsenic exposure resulted in a 2 fold decrease in HSP induction. In rotifers exposed to metal mixtures, HSP60 was induced by the presence of As-Zn, As-Cr-Cu-Pb, As-Cr-Cu, As-Cr-Cu-Ni and As-Cr-CuNi-Pb combinations in the media. HSP60 response to As and heavy metals toxicity depends on the type and number of elements present in the media as well as their concentrations and length of the exposure time.",
Arsenic,627743,"Selected markers of cardiovascular disease in a population exposed to arsenic from drinking water Abstract: This study examined prevalence and serum levels of selected markers of cardiovascular disease in 34 subjects from a Croatian rural population exposed to high levels of arsenic (As) from drinking water (611.89 +/- 10.06 ?g/l). The prevalences of overweight and obese subjects in the population were 32% and 35%. Half the subjects had hypertension, 29% had increased fasting serum glucose level and two were diabetic. Median total cholesterol (5.82 mmol/l) and triglycerides (2.15 mmol/l) were above the desirable margins. The median C-reactive protein level (1.20 mg/l) was slightly higher than previously reported for healthy subjects. Serum Hsp70 level was significantly higher in nonsmokers. Total urinary As levels were positively correlated with age-adjusted serum levels of cobalamin. Near significance were also serum total bilirubin, antibodies to Hsp60 and folate. Tentative investigation of risk factors among subjects classified by tumor necrosis factor-? ?308G/A and interleukin-6-174G/C gene polymorphisms was also performed. Collectively, the results are in agreement with the hypothesis of As-induced and/or compounded cardiovascular disease.",
Arsenic,1508713,"Arsenite modifies structure of soil microbial communities and arsenite oxidization potential Abstract: The influence of arsenite [As(III)] on natural microbial communities and the capacity of exposed communities to oxidize As(III) has not been well explored. In this study, we conducted soil column experiments with a natural microbial community exposed to different carbon conditions and a continuous flow of As(III). We measured the oxidation rates of As(III) to As(V), and the composition of the bacterial community was monitored by 454 pyrosequencing of 16S rRNA genes. The diversity of As(III)-oxidizing bacteria was examined with the aox gene, which encodes the enzyme involved in As(III) oxidation. Arsenite oxidation was high in the live soil regardless of the carbon source and below detection in sterilized soil. In columns amended with 200 ?mol kg(-1) of As (III), As(V) concentrations reached 158 ?mol kg(-1) in the column effluent, while As(III) decreased to unmeasurable levels. Although the number of bacterial taxa decreased by as much as twofold in treatments amended with As(III), some As(III)-oxidizing bacterial groups increased up to 20-fold. Collectively, the data show the large effect of As(III) on bacterial diversity, and the capacity of natural communities from a soil with low initial As contamination to oxidize large inputs of As(III).",
Arsenic,1797805,"A population-based case-control study of urinary arsenic species and squamous cell carcinoma in New Hampshire, USA Abstract: <strong>BACKGROUND: </strong>Chronic high arsenic exposure is associated with squamous cell carcinoma (SCC), and inorganic arsenic metabolites may play an important role in this association. However, little is known about the carcinogenicity of arsenic at levels commonly observed in the U.S.<br /><br /><strong>OBJECTIVE: </strong>To estimate associations between total urinary arsenic and arsenic species and SCC in a U.S. population.<br /><br /><strong>METHODS: </strong>We conducted a population-based case-control SCC study (n = 470 cases, 447 controls) in a U.S. region with moderate arsenic exposure through private well water and diet. We measured urinary inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and summed these arsenic species (sAs). Participants who reported seafood consumption for 2 days before urine collection were excluded from analyses, as seafood contains arsenolipids and arsenosugars that metabolize into DMA through alternate pathways.<br /><br /><strong>RESULTS: </strong>In adjusted logistic regression analyses (n = 323 cases, 319 controls), the SCC odds ratio (OR) was 1.37 for each unit increase in ln(sAs (?g/L)) (95% CI: 1.04, 1.80). Urinary ln(MMA) and ln(DMA) also were positively associated with SCC (OR = 1.34; 95% CI: 1.04, 1.71 and OR = 1.34; 95% CI: 1.03, 1.74, respectively). A similar trend was observed for ln(iAs) (OR = 1.20; 95% CI: 0.97, 1.49). Percent iAs, MMA, and DMA were not associated with SCC.<br /><br /><strong>CONCLUSIONS: </strong>These results suggest that arsenic exposure at levels common in the U.S. relates to SCC and that arsenic metabolism ability does not modify the association.",
Arsenic,1337356,"F18-FDG-PET/CT thyroid incidentalomas: A wide retrospective analysis in three Italian centres on the significance of focal uptake and SUV value Abstract: Thyroid incidental uptake is defined as a thyroid uptake incidentally and newly detected by imaging techniques performed for an unrelated purpose and especially for non-thyroid diseases. Aim of the study was to establish the prevalence and pathological nature of focal thyroid incidentalomas detected at F18-FDG-PET/CT in patients studied for oncological purposes and not for thyroid disease. Secondary end point was to establish a possible maximum standardised uptake value cut-off over which a malignant lesion should be suspected. We have retrospectively evaluated 49519 patients who underwent F18-FDG-PET/CT for oncologic purposes in three Nuclear Medicine Centres (N.1 = 11278, N.2 = 31076, N.3 = 7165). A focal incidental thyroid uptake was diagnosed in 729 (1.5 %) patients (287-39.4 % male and 442-60.6 % female; average age: 65.26). Of 729 thyroid incidentalomas 211 (28.9 %) underwent further investigation to determine the nature of the nodule; 124/211 (58.8 %) incidentalomas were benign, 72/211 (34.1 %) malignant, 4/211 (1.9 %) non-diagnostic at cytological examination in the absence of surgery and histological evaluation and 11/211 (5.2 %) were indeterminate at cytological examination. A centre-based receiver operating curve (ROC) analysis of the patients with a definitive diagnosis was performed to identify a SUVmax cut-off useful in differentiating benign from malignant incidentalomas. In the centre N.1 it was 4.8 (sensitivity = 95.7 %, specificity = 46.4 %, area under the curve = 0.758); 5.3 in the centre N.2 (sensitivity = 76.3 %, specificity = 72.5 %, area under the curve = 0.815); 7 in the centre N.3 (sensitivity = 57.1 %, specificity = 79.3 %, area under the curve = 0.627). F18-FDG-PET/CT thyroid incidentalomas are a relevant diagnostic reality which requires further investigations and clinical management especially considering that, despite mainly benign, approximately one third of focal thyroid uptakes are malignant.",
Arsenic,2088313,"Evaluation of heavy metals in tissue of shellfish from Can Gio coastline in Ho Chi Minh City, Vietnam Abstract: This study was undertaken to determine levels of contamination of toxic metals consumed shellfish products from Can Gio coastline located in southeast of Ho Chi Minh City, Vietnam. Concentrations of As, Cd, Pb, Cr and Mn were determined in edible tissues of Mud Clam (Geloina coaxans), Clam (Meretrix lyrata), Subcrenata (Anadara subcrenata), Blood cockle (Anadara granosa), Asian green mussel (Perna viridis), White leg shrimp (Litopenaeus vannamei), Mud Crab (Scylla serrata) and Periwinkle (Litorina littorea). Sampling was carried out from March to April in 2012. Metal analysis was performed by atomic absorption spectrometry. Concentrations of As, Cd, Pb, Cr and Mn in tissue ranged from Nd-0.67, 0.04-0.64, 0.10-2.51, 0.26-0.47 and 0.75-67.41 mu g g(-1), respectively. The concentrations of heavy metals in all samples were lower than the permitted level set by ministry of health vietnam (MHV) and food and drug agent (FDA) except Pb in Scylla serrata. Therefore, the consumption of shellfish from Can Gio coastline might not pose a risk of metal toxicity. However, monitoring of the levels of As, Cd, Pb, Cr and Mn in water and shellfish should be carried out routinely so that appropriate prevention of contamination from these toxic metals can be implemented.",
Arsenic,627776,"Estimation of multimedia inorganic arsenic intake in the US population Abstract: Arsenic is widely distributed in the environment by natural and human means. The potential for adverse health effects from inorganic arsenic depends on the level and route of exposure. To estimate potential health risks of inorganic arsenic, the apportionment of exposure among sources of inorganic arsenic is critical. In this study, daily inorganic arsenic intake of U.S. adults from food, water, and soil ingestion and from airborne particle inhalation was estimated. To account for variations in exposure across the U.S., a Monte Carlo approach was taken using simulations for 100,000 individuals representing the age, gender, and county of residence of the U.S. population based on census data. Our analysis found that food is the greatest source of inorganic arsenic intake and that drinking water is the next highest contributor. Inhalation of airborne arsenic-containing particles and ingestion of arsenic-containing soils were negligible contributors. The exposure is best represented by the ranges of inorganic arsenic intake (at the 10th and 90th percentiles), which were 1.8 to 11.4 µg/day for males and 1.3 to 9.4 µg/day for females. Regional differences in inorganic arsenic exposure were due mostly to consumption of drinking water containing differing inorganic arsenic content rather than to food preferences.",
Arsenic,2347705,"Exposure-affecting factors of dairy farmers' exposure to inhalable dust and endotoxin Abstract: Introduction: Studies on determinants of dairy farmers’ exposure to dust and endotoxin have been sparse and so far none has addressed the combined effect of tasks and farm characteristics. Objective: To study whether and how work tasks and specific stable characteristics influence the level of dairy farmers’ personal exposure to inhalable dust and endotoxin. Methods: We applied an observational design involving full-shift repeated personal measurements of inhalable dust and endotoxin exposure among 77 subjects (owners and farm workers) from 26 dairy farms. Performed tasks were self-registered in activity diaries, and information on stable characteristics was collected through personal interviews and walk-through surveys. Associations between exposure, tasks, and stable characteristics were examined in linear mixed-effect models with individual and farm treated as random effects. Separate as well as combined models for tasks and stable characteristics were elaborated. Results: The 124 personal samples collected had a geometric mean level (geometric standard deviation) of 360 EU m?3 (3.8) for endotoxin exposure and of 1.0mg m?3 (2.7) for dust exposure. Identified factors that increased endotoxin exposure included a lower outdoor temperature and use of slope-based or back-flushed slurry systems along with milking, distribution of bedding, and handling of feed and seeds in barns. For dust, exposure was higher when fully automatic (robotic) milking was used and during re-penning of animals, handling of feed and seeds, handling of silos and when distributing bedding. Dust exposure increased also as a result of use of rail feed dispensers in a model without fully automatic milking. Conclusions: The current exposure to dust and in particular endotoxin among Danish dairy farmers demand effective strategies to reduce their exposure. The present findings suggest that future interventions should focus on feeding and manure handling systems. Use of respirators during handling of feed and distribution of bedding should be advised until adequate risk management measures have been established. The expected increased use of fully automatic milking in the future might increase dust exposure of dairy farmers.",
Arsenic,1325660,"Arsenic bioaccessibility in cooked rice as affected by arsenic in cooking water Abstract: ? Rice can easily accumulate arsenic (As) into its grain and is known to be the highest As-containing cereal. In addition, the As burden in rice may increase during its processing (such as when cooking using As-polluted water). The health risk posed by the presence of As in cooked rice depends on its release from the matrix along the digestive system (bioaccessibility). Two types of white polished long-grain rice, namely, nonparboiled and parboiled (total As: 202 and 190 ?g As kg(-1) , respectively), were cooked in excess of water with different levels of As (0, 10, 47, 222, and 450 ?g As L(-1) ). The bioaccessibility of As from these cooked rice batches was evaluated with an in vitro dynamic digestion process. Rice cooked with water containing 0 and 10 ?g As L(-1) showed lower As concentrations than the raw (uncooked) rice. However, cooking water with relatively high As content (?47 ?g As L(-1) ) significantly increased the As concentration in the cooked rice up to 8- and 9-fold for the nonparboiled and parboiled rice, respectively. Parboiled rice, which is most widely consumed in South Asia, showed a higher percentage of As bioaccessibility (59% to 99%) than nonparboiled rice (36% to 69%) and most of the As bioaccessible in the cooked rice (80% to 99%) was released easily during the first 2 h of digestion. The estimation of the As intake through cooked rice based on the As bioaccessibility highlights that a few grams of cooked rice (less than 25 g dry weight per day) cooked with highly As contaminated water is equivalent to the amount of As from 2 L water containing the maximum permissible limit (10 ?g As L(-1) ). Practical Application:? Studies on As bioaccessibility are needed for determining human As intake from rice for use in accurate risk assessments to establish updated legislation regarding maximum level of As in food. High As bioaccessibility from parboiled rice (consumed by the majority of the people in South Asia), and the findings of high As levels in discarded rice gruel (fed to livestock), has implications for human and animal health.",
Arsenic,1509323,Assessment of naturally occurring arsenic contamination in the groundwater of Sarkisla Plain (Sivas/Turkey) Abstract: ,
Arsenic,54467,"Correlations between carcinogenic trace metals in water supplies and cancer mortality Abstract: The correlation between cancer and carcinogenic trace metals in water supplies was analyzed. Trace metals selected for analysis were: arsenic (7440382), beryllium (7440417), cadmium (7440439), chromium (7440473), cobalt (7440484), iron (7439896), lead (7439921), and nickel (7440020). Ten major water basins in the United States were selected. A summary statistic that consisted of the frequency of detection and the average detected concentration of each given metal was calculated for each basin. With this summary statistic, a rank ordering of the basins for the eight metals in question was determined. s rank was compared to the rank of the state or states included within each basin for each of 34 types of cancer. Spearman rank correlations were calculated for each of four population groups defined as white males, white females, nonwhite males and nonwhite females. With 8 metals and 34 cancers, there were 272 comparisons made. Twenty eight positive correlations were found at a level of 5 percent significance. The excessive positive correlations were observed for cadmium and lead. For chromium, cobalt, and iron there were no positive correlations significant at the 5 percent level. The authors suggest that there is a need for studies designed to specifically test the linkage hypotheses of metals to cancer in view of the increase of such elements in our environment.",
Arsenic,1027554,"Ars2 links the nuclear cap-binding complex to RNA interference and cell proliferation Abstract: Here we identify a component of the nuclear RNA cap-binding complex (CBC), Ars2, that is important for miRNA biogenesis and critical for cell proliferation. Unlike other components of the CBC, Ars2 expression is linked to the proliferative state of the cell. Deletion of Ars2 is developmentally lethal, and deletion in adult mice led to bone marrow failure whereas parenchymal organs composed of nonproliferating cells were unaffected. Depletion of Ars2 or CBP80 from proliferating cells impaired miRNA-mediated repression and led to alterations in primary miRNA processing in the nucleus. Ars2 depletion also reduced the levels of several miRNAs, including miR-21, let-7, and miR-155, that are implicated in cellular transformation. These findings provide evidence for a role for Ars2 in RNA interference regulation during cell proliferation.",
Arsenic,1024651,"A history of arsenic in dentistry Abstract: The history of the use of arsenic in dentistry has been relegated to dental history. Once hailed as a panacea for the relief of pain and the answer to root canal therapy, it soon fell out of use mainly because of its misuse by unskilled and unscrupulous dentists in search of a quick fix to a complex problem. Such is the story of arsenic.",
Arsenic,2279308,"High fat diet aggravates arsenic induced oxidative stress in rat heart and liver Abstract: Arsenic is a well known global groundwater contaminant. Exposure of human body to arsenic causes various hazardous effects via oxidative stress. Nutrition is an important susceptible factor which can affect arsenic toxicity by several plausible mechanisms. Development of modern civilization led to alteration in the lifestyle as well as food habits of the people both in urban and rural areas which led to increased use of junk food containing high level of fat. The present study was aimed at investigating the effect of high fat diet on heart and liver tissues of rats when they were co-treated with arsenic. This study was established by elucidating heart weight to body weight ratio as well as analysis of the various functional markers, oxidative stress biomarkers and also the activity of the antioxidant enzymes. Histological analysis confirmed the biochemical investigations. From this study it can be concluded that high fat diet increased arsenic induced oxidative stress.",
Arsenic,656634,"Exposure to arsenic at levels found in U.S. drinking water modifies expression in the mouse lung Abstract: The mechanisms of action of drinking water arsenic in the lung and the threshold for biologic effects remain controversial. Our study utilizes Affymetrix 22,690 transcript oligonucleotide microarrays to assess the long-term effects of increasing doses of drinking water arsenic on expression levels in the mouse lung. Mice were exposed at levels commonly found in contaminated drinking water wells in the United States (0, 0.1, 1 ppb), as well as the 50 ppb former maximum contaminant level, for 5 weeks. The expression profiles revealed modification of a number of important signaling pathways, many with corroborating evidence of arsenic responsiveness. We observed statistically significant expression changes for transcripts involved in angiogenesis, lipid metabolism, oxygen transport, apoptosis, cell cycle, and immune response. Validation by reverse transcription-PCR and immunoblot assays confirmed expression changes for a subset of transcripts. These data identify arsenic-modified signaling pathways that will help guide investigations into mechanisms of arsenic's health effects and clarify the threshold for biologic effects and potential disease risk.",
Arsenic,1797808,"Arsenic stabilization by zero-valent iron, bauxite residue, and zeolite at a contaminated site planting Panax notoginseng Abstract: Panax notoginseng (Burk.) F.H. Chen, a rare traditional Chinese medicinal herb, is a widely used phytomedicine used all over the world. In recent years, the arsenic contamination of the herb and its relative products becomes a serious problem due to elevated soil As concentration. This study aimed to evaluate the effects of different types and dosages of amendments on As stabilization in soil and its uptake by P. notoginseng. Results showed that comparing to control treatment, the As concentrations of P. notoginseng declined by 49-63%, 43-61% and 52-66% in 0.25% zero-valent iron (Fe(0)), 0.5% bauxite residue, and 1% zeolite treatment, respectively; whereas the biomasses were elevated by 62-116%, 45-152% and 114-265%, respectively. The As(III) proportions of P. notoginseng increased by 8%, 9%, and 8%, and the transfer factors of As from root to shoot increased by 37%, 42% and 84% in the optimal treatments of Fe(0), bauxite residue, and zeolite. For soil As, all the three amendments could transform the non-specifically adsorbed As fraction to hydrous oxides Fe/Al fractions (by Fe(0) and red mud) or specifically adsorbed As fraction (by zeolite), therefore reduced the bioavailability of soil As. With a comprehensive consideration of stabilization efficiency, plant growth, environmental influence, and cost, Fe(0) appeared to be the best amendment, and zeolite could also be a good choice. In conclusion, this study was of significance in developing As contamination control in P. notoginseng planting areas, and even other areas for medicinal herb growing.",
Arsenic,1030216,Arsenic values in various skin diseases: Estimated by activation analysis Abstract: ,
Arsenic,1070359,"Arsenic, cobalt and chromium food web biodilution in a Patagonia mountain lake Abstract: Mussels, Diplon chilensis, from Lake Moreno, a double-basined mountain lake in southern Argentina, is known to have elevated concentrations of chromium (Cr, &gt;25?gg(-1) dry weight DW) and arsenic (As, 35?gg(-1) DW), attributed to untreated sewage. To further understand the trophodynamics of Cr, As and cobalt (Co), we investigated concentrations and transfer throughout the food web in each basin of Lake Moreno. Each basin differs in morphology in that the gently-sloping Lake Moreno West has more littoral habitat than deeper Lake Moreno East with its higher proportion of pelagic habitat. Despite the morphological differences, both basins share similar water quality parameters and species assemblages. As a result, Lake Moreno provides an exceptional opportunity to compare trophodynamics of elements that enable us to hypothesize pelagic-littoral habitat coupling in response to lake morphology as the underlying factor influencing both Cr pathway and Co and As trophodynamic modeling. Using stable isotopes of nitrogen (?(15)N) and carbon (?(13)C) to characterize metals trophodynamics in each basin, biodilution of As, Cr and Co were indicated by negative regressions. This is confirmed by elevated As, Co and Cr concentrations in phytoplankton (11.3±5.7, 7.4±4.9, 44.5±40.7?gg(-1) DW respectively), while zooplankton and biofilm had the next elevated concentrations. Those elevated concentrations are in contrast with lower concentrations in sport fish such as rainbow trout (0.5±0.5, 0.2±0.3, 1.8±1.2?gg(-1) DW). Higher concentrations of Cr in fish were associated with higher proportion of benthic/littoral prey items in western basin, and were confirmed by significant correlation with ?(13)C values. Arsenic, Co and Cr concentrations in fish, while elevated, do not post health risks to human or wildlife consumers.",
Arsenic,2064213,"Nitric oxide alleviates arsenic-induced toxic effects in ridged Luffa seedlings Abstract: Hydroponic experiments were conducted to investigate whether exogenous addition of nitric oxide (NO) as sodium nitroprusside (SNP) alleviates arsenic (As) toxicity in Luffa acutangula (L.) Roxb. seedlings. Arsenic (5 and 50 ?M) declined growth of Luffa seedlings which was accompanied by significant accumulation of As. SNP (100 ?M) protected Luffa seedlings against As toxicity as it declined As accumulation significantly. The photosynthetic pigments and chlorophyll fluorescence parameters such as Fv/Fm, Fv/F0, Fm/F0 and qP were decreased while NPQ was raised by As. However, the toxic effects of As on photosynthesis were significantly ameliorated by SNP. The oxidative stress markers such as superoxide radical, hydrogen peroxide and malondialdehyde (lipid peroxidation) contents were enhanced by As, however, these oxidative indices were diminished significantly in the presence of SNP. As treatment stimulated the activities of SOD and CAT while the activities of APX and GST, and AsA content and AsA/DHA ratio were decreased. Upon SNP addition, along with further rise in SOD and CAT activity, APX and GST activity, and levels of AsA and AsA/DHA ratio were restored considerably. Overall results revealed that significant accumulation of As suppressed growth, photosynthesis, APX and GST activities and decreased AsA content, hence led to the oxidative stress. However, the addition of SNP protected seedlings against As stress by regulating As accumulation, oxidative stress and antioxidant defense system.",
Arsenic,1337687,"Photocatalytical removal of inorganic and organic arsenic species from aqueous solution using zinc oxide semiconductor Abstract: The photocatalytic removal of arsenite [As(iii)] and monomethylarsonic acid [MMA(v)] was investigated in the presence of UV light (350 nm) and aqueous suspensions of ZnO synthesized by the sol-gel technique. Photocatalytic removal of these potent arsenic compounds results in the effective and rapid mineralization to less toxic inorganic arsenate [As(v)]. The effect of ZnO loading and solution pH on the treatment efficiency of the UV/ZnO photocatalytic process was evaluated. The optimal conditions for the removal of 5 mg L(-1) [As(iii)] and [MMA(v)] aqueous solutions were observed at catalyst loadings of 0.25 and 0.50 g L(-1) with solution pH values of 7 and 8, respectively. Under these conditions, the activity of photocatalyst sol-gel ZnO was compared with TiO(2) Degussa P25 and commercial ZnO catalyst. The results demonstrate that the high adsorption capacity of ZnO synthesized by sol-gel gives enhanced removal of arsenic species from water samples, indicating that this catalyst is a promising material for treatment of arsenic contaminated groundwater.",
Arsenic,1338643,"Arsenic mobilization in the aquifers of three physiographic settings of West Bengal, India: Understanding geogenic and anthropogenic influences Abstract: A comparative hydrogeochemical study was carried out in West Bengal, India covering three physiographic regions, Debagram and Chakdaha located in the Bhagirathi-Hooghly alluvial plain and Baruipur in the delta front, to demonstrate the control of geogenic and anthropogenic influences on groundwater arsenic (As) mobilization. Groundwater samples (n=90) from tube wells were analyzed for different physico-chemical parameters. The low redox potential (Eh=-185 to -86mV) and dominant As(III) and Fe(II) concentrations are indicative of anoxic nature of the aquifer. The shallow (&lt;100m) and deeper (&gt;100m) aquifers of Bhagirathi-Hooghly alluvial plains as well as shallow aquifers of delta front are characterized by Ca(2+)HCO(3)(-) type water, whereas Na(+) and Cl(-) enrichment is found in the deeper aquifer of delta front. The equilibrium of groundwater with respect to carbonate minerals and their precipitation/dissolution seems to be controlling the overall groundwater chemistry. The low SO(4)(2-) and high DOC, PO(4)(3-) and HCO(3)(-) concentrations in groundwater signify ongoing microbial mediated redox processes favoring As mobilization in the aquifer. The As release is influenced by both geogenic (i.e. geomorphology) and anthropogenic (i.e. unsewered sanitation) processes. Multiple geochemical processes, e.g., Fe-oxyhydroxides reduction and carbonate dissolution, are responsible for high As occurrence in groundwaters.",
Arsenic,2345670,"Arsenic exposure and cell-mediated immunity in pre-school children in rural Bangladesh Abstract: Prenatal arsenic exposure has been associated with reduced thymic index and increased morbidity in infants, indicating arsenic-related impaired immune function. We aimed at elucidating potential effects of pre- and postnatal arsenic exposure on cell-mediated immune function in pre-school aged children. Children born in a prospective mother-child cohort in rural Bangladesh were followed up at 4.5 years of age (n = 577). Arsenic exposure was assessed by concentrations of arsenic metabolites (U-As) in child urine and maternal urine during pregnancy, using high-performance liquid chromatography online with inductively coupled plasma mass spectrometry. For assessment of delayed type hypersensitivity response, an intradermal injection of purified protein derivative (PPD) was given to Bacillus Calmette-Guerin vaccinated children. The diameter (mm) of induration was measured after 48-72 h. Plasma concentrations of 27 cytokines were analyzed by a multiplex cytokine assay. Children's concurrent, but not prenatal, arsenic exposure was associated with a weaker response to the injected PPD. The risk ratio (RR) of not responding to PPD (induration &lt;5 mm) was 1.37 (95% confidence interval (CI): 1.07, 1.74) in children in the highest quartile of U-As (range 126-1228 ?g/l), compared with the lowest (range 12-34 ?g/l). The p for trend across the quartiles was 0.003. The association was stronger in undernourished children. Children's U-As in tertiles was inversely associated with two out of 27 cytokines only, i.e., IL-2 and TNF-?, both Th1 cytokines (in the highest tertile, regression coefficients (95% CI): -1.57 (-2.56, -0.57) and -4.53 (-8.62, -0.42), respectively), but not with Th2 cytokines. These associations were particularly strong in children with recent infections. In conclusion, elevated childhood arsenic exposure appeared to reduce cell-mediated immunity, possibly linked to reduced concentrations of Th1 cytokines.",
Arsenic,1018515,"Consideration of background exposures in the management of hazardous waste sites: a new approach to risk assessment Abstract: The current approach to health risk assessment of toxic waste sites in the U.S. may lead to considerable expenditure of resources without any meaningful reduction in population exposure. Risk assessment methods used generally ignore background exposures and consider only incremental risk estimates for maximally exposed individuals. Such risk estimates do not address true public health risks to which background exposures also contribute. The purpose of this paper is to recommend a new approach to risk assessment and risk management concerning toxic waste sites. Under this new approach, which we have called public health risk assessment, chemical substances would be classified into a level of concern based on the potential health risks associated with typical national and regional background exposures. Site assessment would then be based on the level of concern for the particular pollutants involved and the potential contribution of site contaminants to typical background human exposures. While various problems can be foreseen with this approach, the key advantage is that resources would be allocated to reduce the most important sources of human exposure, and site remediation decisions could be simplified by focussing on exposure assessment rather than questionable risk extrapolations.",
Arsenic,627371,"The risk of arsenic induced skin lesions in Bangladeshi men and women is affected by arsenic metabolism and the age at first exposure Abstract: It is known that a high fraction of methylarsonate (MA) in urine is a risk modifying factor for several arsenic induced health effects, including skin lesions, and that men are more susceptible for developing skin lesions than women. Thus, we aimed at elucidating the interaction between gender and arsenic metabolism for the risk of developing skin lesions. This study is part of a population-based case-referent study concerning the risk for skin lesions in relation to arsenic exposure via drinking water carried out in Matlab, a rural area 53km south-east of Dhaka, Bangladesh. We randomly selected 526 from 1579 referents and all 504 cases for analysis of arsenic metabolites in urine using HPLC coupled to inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS). The present study confirm previous studies, with the risk for skin lesions being almost three times higher in the highest tertile of %MA (adjusted OR 2.8, 95% CI: 1.9–4.2, p b 0.001) compared to the lowest tertile. The present study is the first to show that the well documented higher risk for men to develop arsenic-related skin lesions compared to women is mainly explained by the less efficient methylation of arsenic, as defined by a higher fraction of MA and lower fraction of DMA in the urine, among men. Our previously documented lower risk for skin lesions in individuals exposed since infancy, or before, was found to be independent of the observed arsenic methylation efficiency. Thus, it can be speculated that this is due to a programming effect of arsenic in utero.",
Arsenic,2347613,"Brevibacillus sp. KUMAs2, a bacterial isolate for possible bioremediation of arsenic in rhizosphere Abstract: Arsenic (As) contamination of soil and water has been considered as a major global environmental issue during last few decades. Among the various methods so far reported for reclamation of As contaminated rhizosphere soil, bioremediation using bacteria has been found to be most promising. An As resistant bacterial isolate Brevibacillus sp. KUMAs2 was obtained from As contaminated soil of Nadia, West Bengal, India, which could resist As(V) and As(III) a maximum of 265mM and 17mM, respectively. The strain could remove ~40 percent As under aerobic culture conditions. As resistant property in KUMAs2 was found to be plasmid-borne, which carried both As oxidizing and reducing genes. The strain could promote chilli plant growth under As contaminated soil environment by decreasing As accumulation in plant upon successful colonization in the rhizosphere, which suggests the possibility of using this isolate for successful bioremediation of As in the crop field.",
Arsenic,1508714,"Enhancement of arsenic adsorption during mineral transformation from siderite to goethite: mechanism and application Abstract: Synthesized siderite was used to remove As(III) and As(V) from water solutions under anoxic conditions and oxic conditions. Results showed that As adsorption on synthetic siderite under anoxic conditions was around 10 mg/g calculated with Langmuir isotherm. However, the calculated As adsorption on synthetic siderite under oxic conditions ranged between 115 and 121 mg/g, which was around 11 times higher than that under anoxic conditions. It was found that 75% siderite was transformed into goethite during oxic adsorption. However, synthetic goethite had lower As adsorption capacity than siderite under oxic conditions, although its adsorption capacity was a little higher than siderite under anoxic conditions. It suggested that the coexistence of goethite and siderite bimineral during mineral transformation probably contributed to the robust adsorption capacity of siderite under oxic conditions. Results of extended X-ray absorption fine structure (EXAF) spectroscopy indicated both As(III) and As(V) formed inner-sphere complexes on the surface of As-treated solid regardless of substrates, including the bidentate binuclear corner-sharing ((2)C) complexes and the monodentate mononuclear corner-sharing ((1)V) complexes. Monodenate ((1)V) and bidentate ((2)C) complexes would be related to high As adsorption capacity of siderite under oxic conditions. It showed that more Fe atoms were coordinated with As atom in the monodentate complexes and the bidentate complexes of As(V)/As(III)-treated siderite under oxic conditions, in comparison with As(V)/As(III)-treated siderite under anoxic conditions and As(V)/As(III)-treated goethite. Calcinations of natural siderite resulting in the coexistence of goethite and siderite greatly increased As adsorption on the solid, which confirmed that the coexistence of bimineral during mineral transformation from siderite to goethite greatly enhanced As adsorption capacity of siderite adsorbent. The observation can be applied for modification of natural siderite for As removal from high As waters.",
Arsenic,656935,"Suppression of cyclin D1 by hypoxia-inducible factor-1 via direct mechanism inhibits the proliferation and 5-fluorouracil-induced apoptosis of A549 cells Abstract: Hypoxia-inducible factor (HIF) and cyclin D1 are both key mediators of cell growth and proliferation in normal and cancer cells. However, the interrelation between HIF and cyclin D1 remains unclear. In the present study, we observed the inverse correlation between cyclin D1 and HIF-1 in hypoxia condition. Overexpression of the dominant negative mutant of HIF-1alpha (DN-HIF) significantly enhanced cyclin D1 expression upon hypoxia or arsenite exposure, suggesting the negative regulation of cyclin D1 by HIF-1. Furthermore, we found that the impairment of HIF-1 increased cyclin D1 expression in A549 pulmonary cancer cells, which in turn promoted G1-S cell cycle transition and cell proliferation. Cyclin D1 expression was increased in s.c. xenograft of DN-HIF stably transfected A549 cells in nude mice compared with that of control cells. Chromatin immunoprecipitation assay revealed that HIF-1 was able to directly bind to the promoter region of cyclin D1, which indicates that the negative regulation of cyclin D1 by HIF-1 is through a direct mechanism. Inhibition of histone deacetylase (HDAC) by pretreatment of cells with trichostatin A or specific knockdown of HDAC7 by its shRNA antagonized the suppression of cyclin D1 by HIF-1, suggesting that HDAC7 is required for HIF-1-mediated cyclin D1 downregulation. Moreover, we found that 5-fluorouracil-triggered apoptosis of DN-HIF-transfected A549 cells was reduced by sicyclin D1 (cyclin D1-specific interference RNA) introduction, suggesting that clinical observation of HIF-1 overexpression-associated chemoresistance might be, at least partially, due to the negative regulation of cyclin D1.",
Arsenic,1018872,"Inhibition of human plasmin activity using humic acids with arsenic Abstract: In this study, we examined the effects of natural humic acid (HA) purified from drinking well-water in Blackfoot disease (BFD) endemic areas, using synthetic humic acid (SHA), such as protocatechuic acid, ferulic acid, vanillic acid or catechol, and trivalent arsenic on human plasmin activity. Data in this report indicated that both HA and SHA inhibited human plasmin activity by 20-80 and 5-95%, respectively, at concentrations of 20-480 microg/ml. Organometallic complexes composed of HA and arsenic show enhanced inhibition of plasmin activity as compared with either HA or arsenic alone. Monomers of HA or arsenic alone do not inhibit plasma activity. Oxidative stress may play a role in the inhibition of plasma activity, as various free-radical scavengers, such as ascorbic acid, alpha-tocopherol, catalase and superoxide dismutase (SOD), abrogate the inhibitory effects of HA and HA-arsenic complexes. The notion that HA/organometallic complexes (HA/OR) impaired plasmin activity was significant, due to the fact that both of these agents (HA and arsenic) are etiological factors in the development of peripheral vascular diseases, such as BFD. This report substantiates the inhibitory effects of HA/OR on plasmin activity, and thus provides evidence for the partial mechanism of action of HA/OR in BFD.",
Arsenic,2345801,"Risk assessment of heavy metals and their source distribution in waters of a contaminated industrial site Abstract: Industrially contaminated sites with hazardous materials are a priority and urgent problem all over the world. Appropriate risk assessment is required to determine health risks associated with contaminated sites. The present study was conducted to investigate distribution of potentially hazardous, heavy metal (As, Cd, Cr, Cu, Ni, Pb and Zn) concentrations in surface and groundwater samples collected during summer (pre-monsoon) and winter (post-monsoon) seasons from an industrially contaminated site, Hyderabad, India, with potential source of metal contamination because of industrial effluents and usage of pesticides in agriculture. Heavy metal (HM) concentrations were analysed by using inductively coupled plasma-mass spectrometer and were compared with permissible limits set by the World Health Organisation. Data obtained was treated using multivariate statistical approaches like R-mode factor analysis (FA), principal component analysis, cluster analysis, geoaccumulation index, enrichment factor, contamination factor and the degree of contamination. Health risk assessment like chronic daily intake (CDI) and hazard quotient (HQ) were also calculated. Relatively high levels were noted in surface water with average concentrations during summer and winter seasons showing 16.13 and 11.83 for As, 7.91 and 1.64 for Cd, 88.33 and 32.90 for Cr, 58.11 and 28.26 for Cu, 53.62 and 69.96 for Ni, 173.8 and 118.6 for Pb, and 2,943 and 1,889 ?g/L for Zn. While in groundwater, the mean metal levels during two seasons were 18.18 and 3.76 for As, 1.67 and 0.40 for Cd, 29.40 and 5.15 for Cr, 17.03 and 4.19 for Cu, 25.4 and 6.09 for Ni, 81.7 and 2.87 for Pb and 953 and 989 ?g/L for Zn, respectively. FA identified two factors with cumulative loadings of F1-60.82 % and F2-76.55 % for pre-monsoon surface water and F1-48.75 % and F2-67.55 % for groundwater. Whereas, three factors with cumulative loadings of F1-39.13 %, F2-66.60 % and F3-81.01 % for post-monsoon surface water and F1-50.31 %, F2-66.18 % and F3-81.54 % for groundwater. The health risk assessment like CDI and HQ indices with increased levels of hazardous elements in the surface and groundwater were safe for drinking purposes provided some water treatment methodologies are adopted.",
Arsenic,1032253,"Reversal of gallium arsenide-induced suppression of the antibody-forming cell response by vehicle supernatants. I. Pharmacokinetics after in vitro and in vivo exposure Abstract: Exposure of splenocytes in vivo or in vitro to gallium arsenide (GaAs) dose-dependently suppresses the ability of these cells to produce antibody after in vitro immunization with sheep red blood cells. In addition, it has been demonstrated that GaAs exerts immunosuppressive effects early (36 hr) in the generation of a primary antibody-forming cell (AFC) response. The objective of this study was to determine if the GaAs-induced suppression was produced as a result of a GaAs-induced alteration in the secretion of soluble mediators. Supernatants from in vivo and in vitro vehicle (VH)-exposed splenocyte cultures time-dependently reversed GaAs-induced suppression of the in vitro-generated primary AFC response produced by both in vitro (50 ?M) and in vivo (200 mg/kg) exposure to GaAs. Supernatants from in vitro GaAs-exposed cells suppressed the VH response 40, 89 and 93% at 24, 36 and 48 hr, respectively. Using the arsenic-binding compound meso-2,3-dimercaptosuccinic acid (100 ?M), it was determined that the suppression of the VH response by supernatants from in vitro GaAs-exposed cultures was confounded by the presence of free arsenic in the in vitro GaAs-exposed culture supernatant. In contrast, suppression of in vivo VH-exposed AFC responses by supernatants from in vivo GaAs-exposed cells was not seen. The time-dependent reversal of immunosuppression produced by in vivo or in vitro exposure to GaAs, by supernatants from in vivo and in vitro VH-exposed cells mimics the reported kinetics of suppression by addition of GaAs to antibody cultures.",
Arsenic,1337293,"Distribution and chemical speciation of arsenic and heavy metals in highly contaminated waters used for health care purposes (Srebrenica, Bosnia and Herzegovina) Abstract: Determination of distribution and chemical speciation of arsenic and heavy metals in five acidic springs and in the receiving river near Srebrenica (Bosnia and Herzegovina) was carried out. These waters were used for centuries, and continue to be used, for health-care purposes. The composition and properties of all springs and the river water (after all inputs) resembled that of an acid mine drainage. Very low pH (&lt;3.3), high sulphate concentration and extremely high contents of most of the measured elements (25) are found in all springs (e.g. arsenic and iron maximal concentration of 6.6 and 500mgL(-1), respectively). Although of small discharge, spring waters caused the decrease of the receiving river pH (from 7.3 to 3.4) and the considerable increase of the concentrations of elements. The enrichment factor for the studied elements ranged from 1.2 for Sr up to 425 for As. In acidic spring waters, all elements were predominantly present in dissolved form. Elements associated to freshly-formed hydrous ferric oxide were prevailing in particulate forms only at the two most upstream sites in the river with pH&gt;7. Geochemical speciation modelling (PHREEQC and WHAM-VI) revealed that As was mainly present as As(V), and Fe as Fe(III). Complexation of dissolved metals by organic matter was predicted to be significant only for the two river sites with neutral pH.",
Arsenic,627739,"Effects of the plant flavonoids silymarin and quercetin on arsenite-induced oxidative stress in CHO-K1 cells Abstract: Chronic toxic effects of arsenic resulting from drinking water are a human health problem, especially in South-America and Asia. Arsenic is capable of influencing various cellular processes, causing adverse effects, including cancer. Although the exact mechanism of the action is not known, a correlation between oxidative stress, tumour promotion and arsenic exposure has been observed. We examined the effects of silymarin and quercetin, in counteracting oxidative stress produced by acute or sub-chronic sodium arsenite exposure. The stress responses to arsenite included an increase in the heat shock protein 70 kDa expression, lipid peroxidation assayed by conjugated dienes measure, and gamma-glutamyl-transpeptidase activity. We found that all these stress responses were eliminated by silymarin and quercetin in acute experiments. Both flavonoids diminished the conjugated dienes formation during sub-chronic cultures. Our results suggest that these antioxidant flavonoids, which may be easily incorporated into the diet, may afford a protective effect against arsenite-induced cytotoxicity.",
Arsenic,94056,"Hair and toenail arsenic concentrations of residents living in areas with high environmental arsenic concentrations Abstract: Surface soil and groundwater in Australia have been found to contain high concentrations of arsenic. The relative importance of long-term human exposure to these sources has not been established. Several studies have investigated long-term exposure to environmental arsenic concentrations using hair and toenails as the measure of exposure. Few have compared the difference in these measures of environmental sources of exposure. In this study we aimed to investigate risk factors for elevated hair and toenail arsenic concentrations in populations exposed to a range of environmental arsenic concentrations in both drinking water and soil as well as in a control population with low arsenic concentrations in both drinking water and soil. In this study, we recruited 153 participants from areas with elevated arsenic concentrations in drinking water and residential soil, as well as a control population with no anticipated arsenic exposures. The median drinking water arsenic concentrations in the exposed population were 43.8 Ág/L (range, 16.0-73 Ág/L) and median soil arsenic concentrations were 92.0 mg/kg (range, 9.1-9,900 mg/kg). In the control group, the median drinking water arsenic concentration was below the limit of detection, and the median soil arsenic concentration was 3.3 mg/kg. Participants were categorized based on household drinking water and residential soil arsenic concentrations. The geometric mean hair arsenic concentrations were 5.52 mg/kg for the drinking water exposure group and 3.31 mg/kg for the soil exposure group. The geometric mean toenail arsenic concentrations were 21.7 mg/kg for the drinking water exposure group and 32.1 mg/kg for the high-soil exposure group. Toenail arsenic concentrations were more strongly correlated with both drinking water and soil arsenic concentrations; however, there is a strong likelihood of significant external contamination. Measures of residential exposure were better predictors of hair and toenail arsenic concentrations than were local environmental concentrations.",
Arsenic,1022070,"Oxidative DNA damage estimated by urinary 8-hydroxy-2'-deoxyguanosine and arsenic in glass production workers Abstract: A total of 130 male glass workers, including 33 administrative workers, 18 batch house workers, 42 craftsmen, and 37 melting process workers, were recruited to investigate the potential DNA damage resulting from toxic element exposure. The occupational exposure to trace elements, including arsenic (As), cadmium (Cd), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se), was estimated by their urinary levels as internal doses. In addition, all participants filled a self-filled questionnaire indicating their individual information. The average levels of urinary As, Cd, Mn, Ni, Pb, Se, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were 282.3 ± 464.6, 3.07 ± 5.39, 3.81 ± 11.43, 81.48 ± 138.9, 18.23 ± 49.61, 165.2 ± 224.9, and 17.21 ± 26.34 ?g/g creatinine, respectively. The urinary levels of 8-OHdG and toxic elements were strongly associated with the work nature of the worker, with an exception of Mn and Pb. In contrast, the levels of toxic element were not influenced by age, smoking behavior, and alcohol consumption. The urinary 8-OHdG was found significantly higher in higher internal exposure groups of As, Cd, Ni, and Se. However, the stepwise multiple regression models showed that urinary 8-OHdG was only associated with urinary As and heat stress but inversely with age.",
Arsenic,2345704,"Two-orbital three-electron stabilizing interaction for direct Co2+ - As3+ bonds involving square-planar CoO4 in BaCoAs2O5 Abstract: The quest for new oxides with cations containing active lone-pair electrons (E) covers a broad field of targeted specificities owing to asymmetric electronic distribution and their particular band structure. Herein, we show that the novel compound BaCoAs2O5, with lone-pair As3+ ions, is built from rare square-planar Co2+O4 involved in direct bonding between As3+E and Co2+ d(z2) orbitals (CoAs=2.51 angstrom). By means of DFT and Huckel calculations, we show that this sigma-type overlapping is stabilized by a two-orbital three-electron interaction allowed by the high-spin character of the Co2+ ions. The negligible experimental spin-orbit coupling is expected from the resulting molecular orbital scheme in O3AsE-CoO4 clusters.",
Arsenic,8687,"Metabolism and disposition of inorganic arsenic in laboratory animals and humans Abstract: The carcinogenicity of inorganic arsenic in humans, particularly in the lung and skin, has been reasonably well established through epidemiological investigations. However, there is no substantial experimental evidence for carcinogenicity in animals to suort the human studies. Studies of metabolism and disposition of inorganic arsenic in various animal species are particularly relevant to determining the factors that might account for the lack of an animal model. Numerous studies of this type have been reported, but there do not appear to be clear qualitative or quantitative differences in the overall fate and disposition of inorganic arsenic in most animals versus humans, although little is known at the cellular and subcellular level. Sulphur chemistry, especially thiol status, is emerging as an important regulating factor in the overall fate and distribution of inorganic arsenic in the body, playing a role in the initial reduction of arsenate to arsenite and subsequent methylation, and possibly in determining tissue affinity and distribution properties. The metabolism of inorganic arsenic can be viewed as a redox cycle in which thiol compounds such as glutathione (GSH) possibly function as reducing agents and methyl donors as oxidising agents. One explanation for the possible sensitivity of certain malnourished human populations to the carcinogenic effects of inorganic arsenic may be related to the reduced availability of nonprotein sulphhydryl compounds such as GSH needed to drive the redox cycle and facilitate arsenic detoxification. Future carcinogenicity studies of inorganic arsenic in animals could be designed to address directly this aspect of the problem.",
Arsenic,1030162,"Heat-induced morphological alterations in non-tolerant and thermotolerant cells Abstract: CHO cells were heated at 43 degrees C or 45 degrees C for various durations up to 300 min. Survival values varied from 5 x 10(-1) to 10(-7). Unheated, non-tolerant control cells were compared with cells made thermotolerant (TT) by incubating at 37 degrees C for 6 or 12 h after treatment with either sodium arsenite (100 microM-As) or 45.5 degrees C for 10 min, respectively. Groups also were included in which heat-induced TT cells were heated at 43 degrees C for 5 h immediately before they were challenged at 45 degrees C; in these groups, cycloheximide was sometimes added to inhibit protein synthesis before and/or during heating at 43 degrees C. Morphological alterations were quantified immediately and at various times after heating by using phase-contrast microscopy to determine the percentage of cells that were severely blebbed and rounded. About 800 cells were analysed per datum point. When effects of heat on thermotolerant cells were compared with effects of heat on non-tolerant cells, heat-induced thermotolerance (HTT) was observed by an increase in survival, and by a reduction in the percentage of cells with morphological alteration observed immediately after the challenging heat. After the As treatment, very little thermotolerance was observed for morphological alterations immediately after the challenging heat, although thermotolerance was observed for survival. However, as the cells were incubated for 12 or 24 h at 37 degrees C after the challenging heat treatment, recovery from morphological alterations was observed in the As-TT cells. Possible mechanisms for the difference between HTT and As-TT are discussed.",
Arsenic,1360409,"An evaluation of a local exhaust ventilation control system for a foundry casting-cleaning operation Abstract: A study was conducted to evaluate the effectiveness of a local exhaust ventilation system for a foundry casting-cleaning operation in which a worker cleaned gray iron castings using a variety of handheld chipping and grinding tools. The operation originally had an exhaust system consisting only of an exhaust duct terminating approximately 1 m (3 ft) above the floor and 2 m (6 ft) from the casting-cleaning workstation. An earlier evaluation of this original control system found time-weighted average exposures to respirable silica ranging from 124 to 160 micrograms/m3. The local exhaust ventilation system evaluated in this present study consisted of a downdraft booth outfitted with a turntable for manipulating the castings. The modified local exhaust ventilation system was installed at this facility and connected to the existing plant exhaust ventilation system through the original ductwork. A direct-reading instrument was used to measure the operator's respirable aerosol exposure concentrations during a single day both before and after the installation of the new workstation. The same worker was sampled both times. The operator's activities were recorded on videotape so that the exposures associated with the various tools could be determined. While day-to-day variability could not be accounted for, depending on the type of tool used the local exhaust ventilation system reduced exposures by 59 to 79% during casting cleaning by the sampled worker when compared with the original configuration. These reductions were statistically significant.",
Arsenic,2337080,"Probabilistic evaluation of shallow groundwater resources at a hypothetical carbon sequestration site Abstract: Carbon sequestration in geologic reservoirs is an important approach for mitigating greenhouse gases emissions to the atmosphere. This study first develops an integrated Monte Carlo method for simulating CO2 and brine leakage from carbon sequestration and subsequent geochemical interactions in shallow aquifers. Then, we estimate probability distributions of five risk proxies related to the likelihood and volume of changes in pH, total dissolved solids, and trace concentrations of lead, arsenic, and cadmium for two possible consequence thresholds. The results indicate that shallow groundwater resources may degrade locally around leakage points by reduced pH and increased total dissolved solids (TDS). The volumes of pH and TDS plumes are most sensitive to aquifer porosity, permeability, and CO2 and brine leakage rates. The estimated plume size of pH change is the largest, while that of cadmium is the smallest among the risk proxies. Plume volume distributions of arsenic and lead are similar to those of TDS. The scientific results from this study provide substantial insight for understanding risks of deep fluids leaking into shallow aquifers, determining the area of review, and designing monitoring networks at carbon sequestration sites.",
Arsenic,1337690,"Life-history effects of arsenic toxicity in clades of the earthworm Lumbricus rubellus Abstract: Exposures of Lumbricus rubellus to a series of arsenic concentrations in soil were used to assess life-stage (juvenile, adult) and genotype specific sensitivities, to calculate population growth rate (?) and to assess patterns of As accumulation. Significant mortality was seen in juveniles at 125 mg/kg As, while growth and maturation was affected from 36 mg/kg and above. In adults, cocoon production at the highest concentration (125 mg/kg) was significantly reduced. Phylogenetic analysis was performed by comparison of mitochondrial sequences to establish genotypic variation among juveniles. Three clades with more than 7.5% divergent were described, with 70% of earthworms belonging to a single clade. Date of and mass at maturation was significantly different between clades, but clades were not differentially As sensitive. Parameter ? was reduced at 36 mg/kg As and was negative at 125 mg/kg As, suggesting impacts and population stability and potential extinction at environmentally relevant concentrations.",
Arsenic,1797835,"Trophic Transfer of Trace Elements in an Isotopically Constructed Food Chain From a Semi-enclosed Marine Coastal Area (Stagnone di Marsala, Sicily, Mediterranean) Abstract: Trace element accumulation is particularly important in coastal and transitional environments, which act as contaminant buffers between the continental and marine systems. We compared trace element transfer to the biota in two locations with different open-sea exposures in a semi-enclosed marine coastal area (Stagnone di Marsala, Sicily, Italy) using isotopically reconstructed food chains. Samples of sediment, macroalgae, seagrasses, invertebrates, fish, and bird feathers were sampled in July 2006 and analysed for stable carbon and nitrogen isotopes (?(13)C, ?(15)N) and trace elements (arsenic [As], cadmium [Cd], total mercury [THg], and lead [Pb]). Trophic magnification factors were calculated through the relationships between trace elements and ?(15)N in consumers. As and Pb were greater in organic matter sources (sediments and primary producers), whereas Cd and THg were greater in bird feathers. At the food chain level, an insignificant trophic transfer was found for all elements, suggesting biodilution rather than biomagnification. Sediments were more contaminated in the location with lower open-sea exposure. Macroalgae and seagrasses overall mirrored the spatial pattern highlighted in sediments, whereas differences between the two locations became further decreased moving toward higher trophic levels, indicating that trophic transfer of sediment and macrophyte-bound trace elements to the coastal lagoon food chain may be of relatively minor importance.",
Arsenic,1349165,INDUCTION OF SISTER CHROMATID EXCHANGES BY ARSENIC IN PRIMARY RAT TRACHEAL EPITHELIAL-CELLS Abstract: ,
Arsenic,2064247,"Evaluation of short-term and long-term results after laparoscopic antireflux surgery: Esophageal manometry and 24-h pH monitoring versus quality of life index Abstract: <strong>PURPOSE: </strong>The objective of this long-term study is to compare data on postoperative quality of life with objective functional measurements in patients with gastroesophageal reflux disease who have undergone laparoscopic antireflux surgery.<br /><br /><strong>METHODS: </strong>Between 1995 and 2005, 162 patients with gastroesophageal reflux disease underwent laparoscopic surgery. A minimum of 4 years after surgery, 60 patients were contacted at random, 29 of whom agreed to follow-up examination. The following examinations were performed preoperatively, 6 months postoperatively, and 4-12 years postoperatively: esophageal manometry, 24-h gastroesophageal pH-metry, and assessment of patient quality of life based on the gastrointestinal quality of life index (GIQLI).<br /><br /><strong>RESULTS: </strong>The number of postsurgical reflux episodes was reduced significantly, both at 6 months and at 4 or more years after surgery. The number of episodes dropped from 183 before surgery to 58 at 6 months after surgery and remained constant ?4 years later. Surgery also produced a significant drop in reflux time, seen both 6 months and ?4 years later. Six months after surgery, the median reflux time had fallen from 134 min (preoperatively) to 27 min, and at ??4 years it was still significantly reduced at 35 min. Sphincter length (median preoperative length, 3 cm; median postoperative length (at 6 months and at ?4 years), 4 cm) and sphincter pressure (median preoperative pressure, 3 mmHg; median at 6 months, 12 mmHg; median at ?4 years, 10.9 mmHg) were significantly improved by surgery as well. Finally, surgery produced an improvement in quality of life. The median preoperative GIQLI was 102, while at 6 months after surgery it was 113 and at ?4 years after surgery it was 124.<br /><br /><strong>CONCLUSION: </strong>Laparoscopic fundoplication guarantees long-term improvement in symptoms and quality of life for patients suffering from gastroesophageal reflux disease. The effectiveness of reflux surgery can thus be demonstrated by long-term quality of life assessments and postoperative functional measurements. No statistically significant correlation between total score (DeMeester) and GIQLI could be demonstrated.",
Arsenic,1391119,"Integration Of Biomonitoring Data Into The Risk Assessment Process Abstract: Improved biomonitoring (BM) technologies are being used to measure veryl low levels of environmental chemicals in the tissues of adults, children and developing fetuses. These measurements can show that people have been exposed to chemicals and that these chemicals have been absorbed into the body. However, linkages to exposure on the one hand and linkages to human health on the other are not always clear. The ILSI Biomonitoring workshop explored the process and information needed to put BM information into perspective by associating these data with exposure and potential health outcomes. Key questions associated with the use of BM data were discussed, these included How can BM data be used more widely?, What other data is needed to use BM data in risk assessment?, How might BM data be used inappropriately? Case studie of arsenic, phthalates, perfluorooctance sulfonic acid, polycyclic aromatic hydrocarbons and organophosphates were conducted to evaluate BM data for different classes of chemicals against these questions. The case-studies identified specific scientific issues and developed perspective on broader scientific questions. An overarching need is for the development of consensus criteria similar to the Bradford-Hill criteria that are commonly applied to epidemiology studies for application and interpretation of BM data. In general it was determined that in many cases there is an absence of human toxicokinetic data that are essential when evaluating human exposure relative to animal toxicology data. Furthermore, PBPK and exposure models should be developed along with gaining a clearer understanding of dose metrics are needed. In addition, there is a lack of information on how to identify appropriate biomarkers that reflect low level exposure at or near the threshold for effect. There is also a need to carefully examine the risk assessment paradigm in the context of BM data and to develop a risk communication strategy.",
Arsenic,656738,"Nitric oxide is involved in arsenite inhibition of pyrimidine dimer excision Abstract: Arsenite is a human carcinogen reported to inhibit DNA repair. The binding of arsenite to functional thiol groups of DNA repair enzymes has in the past been suggested as a possible mechanism for the effect of arsenite on DNA repair. However, recent studies indicate that reactive oxygen species and nitric oxide are involved in arsenite toxicity. This research aims to elucidate the role of these possible mechanisms in the inhibition of UV-induced DNA repair by arsenite. As arsenite inhibits UV-DNA repair in Chinese hamster ovary cells, and this is a commonly used cell line for UV repair experiments, we used these cells to examine the effect of arsenite on the expression of UV-irradiated reporter genes. The T4 UV endonuclease V-incorporated comet assay was used to examine specifically the effect of arsenite on pyrimidine dimer excision. We showed that inhibition of UV-DNA repair by arsenite was suppressed by nitric oxide synthase inhibitors. Arsenite increased nitric oxide production and nitric oxide generators inhibited UV-DNA repair. The involvement of nitric oxide in the inhibition of pyrimidine dimer excision by arsenite was also confirmed in human fibroblasts. Investigation into the effect of oxidant modulators did not give a clear indication that reactive oxygen species are involved in arsenite inhibition of UV-DNA repair. Phenylarsine oxide, a strong thiol-reacting agent, did not inhibit pyrimidine dimer excision and also did not increase nitric oxide production. Our results show conclusively that nitric oxide is involved in the inhibition of pyrimidine dimer excision by arsenite. Reactive oxygen species and the binding of arsenite to functional thiol groups of DNA repair enzymes do not appear to be involved.",
Arsenic,1016013,"Effect of urinary total arsenic level and estimated glomerular filtration rate on the risk of renal cell carcinoma in a low arsenic exposure area Abstract: <strong>PURPOSE: </strong>We explored the relationship between urinary total arsenic and risk of renal cell carcinoma, and investigated whether having hypertension or a low estimated glomerular filtration rate would modify the risk of renal cell carcinoma.<br /><br /><strong>MATERIALS AND METHODS: </strong>The case-control study was conducted between November 2006 and May 2009 with 132 patients with renal cell carcinoma, and 260 sex and age matched controls from a hospital based pool. Pathological verification of renal cell carcinoma was completed by image guided biopsy or surgical resection of renal tumors. Urinary arsenic species, including inorganic arsenic, monomethylarsonic acid and dimethylarsinic acid, were determined with a high performance liquid chromatography linked hydride generator and atomic absorption spectrometry. Estimated glomerular filtration rate was calculated using the Modification of Diet in Renal Disease Study equation.<br /><br /><strong>RESULTS: </strong>Urinary total arsenic was significantly associated with renal cell carcinoma risk in a dose-response relationship after multivariate adjustment. Low estimated glomerular filtration rate or hypertension was significantly related to renal cell carcinoma risk. Estimated glomerular filtration rate was significantly negatively related with urinary total arsenic. A significant interaction was seen between the urinary total arsenic and hypertension on renal cell carcinoma risk. The greatest odds ratio (6.01) was seen in the subjects with hypertension, low estimated glomerular filtration rate and high urinary total arsenic. A trend test indicated that the risk of renal cell carcinoma increased along with the accumulating number of these 3 risk factors (p &lt;0.0001).<br /><br /><strong>CONCLUSIONS: </strong>Higher urinary total arsenic level was a strong predictor of renal cell carcinoma, and estimated glomerular filtration rate or hypertension interacts with urinary total arsenic in modifying the risk of renal cell carcinoma.",
Arsenic,1026008,"Exposure to non-arsenic pesticides is associated with lymphoma among farmers in Spain Abstract: <strong>OBJECTIVES: </strong>To estimate the risk of lymphoma among farmers in Spain.<br /><br /><strong>METHODS: </strong>This is a multicentre case control study conducted in Spain. Cases were subjects diagnosed with lymphoma according to the World Health Organization (WHO) classification in four hospitals between 1998-2002. Hospital controls were frequency matched to the cases by sex, age, and centre. All subjects were interviewed about jobs ever held in lifetime for at least one year and the exposures in those jobs were recorded. The risk of lymphomas among subjects ever having had a job as a farmer was compared with all other occupations. Farmers were analysed according to the type of farming job performed: crop farming, animal farming, and general farming. Occupational exposure was summarised into 15 main categories: organic dust, radiation, contact with animals, PAH, non-arsenic pesticides (carbamates, organophosphates, chlorinated hydrocarbons, triazines and triazoles, phenoxy herbicides, chlorophenols, dibenzodioxin, and dibenzofuran), arsenic pesticides, contact with meat, contact with children, solvents, asbestos, soldering fumes, organic colourants, polychlorinated biphenyls, ethylene oxide, and hair dyes.<br /><br /><strong>RESULTS: </strong>Although farmers were not at an increased risk of lymphoma as compared with all other occupations, farmers exposed to non-arsenic pesticides were found to be at increased risk of lymphoma (OR = 1.8, 95% CI 1.1 to 2). This increased risk was observed among farmers working exclusively either as crop farmers or as animal farmers (OR = 2.8, 95% CI 1.3 to 5.8). Risk was highest for exposure to non-arsenic pesticides for over nine years (OR = 2.4, 95% CI 1.2 to 2.8).<br /><br /><strong>CONCLUSIONS: </strong>Long term exposure to non-arsenic pesticides may induce lymphomagenesis among farmers.",
Arsenic,1247811,"Expression of phytochelatin synthase from aquatic macrophyte Ceratophyllum demersum L. enhances cadmium and arsenic accumulation in tobacco Abstract: Phytochelatin synthase (PCS), the key enzyme involved in heavy metal detoxification and accumulation has been used from various sources to develop transgenic plants for the purpose of phytoremediation. However, some of the earlier studies provided contradictory results. Most of the PCS genes were isolated from plants that are not potential metal accumulators. In this study, we have isolated PCS gene from Ceratophyllum demersum cv. L. (CdPCS1), a submerged rootless aquatic macrophyte, which is considered as potential accumulator of heavy metals. The CdPCS1 cDNA of 1,757 bp encodes a polypeptide of 501 amino acid residues and differs from other known PCS with respect to the presence of a number of cysteine residues known for their interaction with heavy metals. Complementation of cad1-3 mutant of Arabidopsis deficient in PC (phytochelatin) biosynthesis by CdPCS1 suggests its role in the synthesis of PCs. Transgenic tobacco plants expressing CdPCS1 showed several-fold increased PC content and precursor non-protein thiols with enhanced accumulation of cadmium (Cd) and arsenic (As) without significant decrease in plant growth. We conclude that CdPCS1 encodes functional PCS and may be part of metal detoxification mechanism of the heavy metal accumulating plant C. demersum. KEY MESSAGE: Heterologous expression of PCS gene from C. demersum complements Arabidopsis cad1-3 mutant and leads to enhanced accumulation of Cd and As in transgenic tobacco.",
Arsenic,1024347,"Role of trichome of Pteris vittata L. in arsenic hyperaccumulation Abstract: Environmental scanning electron microscope (ESEM) fitted with an energy dispersive X-ray microanalyzer (EDX) was used to investigate the surface micromorphology and arsenic (As) micro-distribution in Chinese brake (Pteris vittata L.). It was found that amounts of trichome, which possessed multicellular structure with the average length of 160 microm and with an average diameter of 28 microm, existed in the frond of P. vittata, and the density of trichome on the pinnate axial surface was higher than that on the petiole. Visible X-ray peak of As was recorded in the epidermal cell and trichome. The relative weight of As in the pinnate trichome, which contained the highest concentration of As among all tissues of the plant, was 2.4 and 3.9 times as much as that in the epidermal and mesophyllous cells, respectively. The As concentrations in the basal and stalk cells of the same trichome were higher than that in its cap cell. This is the first time to report that the trichome of P. vittata plays an important role in arsenic hyperaccumulation. The finding from the present study implies that much attention should be paid to the role of the trichome in understanding the hyperaccumulation and detoxicity of As in the hyperaccumulator and improving the ability of As accumulation.",
Arsenic,1250988,"Enhanced arsenate uptake in Saccharomyces cerevisiae overexpressing the Pho84 phosphate transporter Abstract: Arsenate is a major toxic constituent in arsenic-contaminated water supplies. Saccharomyces cerevisiae was engineered as a potential biosorbent for enhanced arsenate accumulation. The phosphate transporter, Pho84p, known to import arsenate, was overexpressed using a 2?-based vector carrying PHO84 under the control of the late-phase ADH2 promoter. Arsenate uptake was then evaluated using a resting cell system. In buffer solutions containing high arsenate concentrations (12,000 and 30,000 ppb), the engineered strains internalized up to 750 ?g of arsenate per gram of cells, a 50% improvement over control strains. Increasing the cell mass 2.5-fold yielded a proportional increase in the volumetric arsenate uptake, while maintaining the same level of specific uptake. At high levels of arsenate, loss from the intact cells to the medium was observed with time; knockouts of two known arsenic extrusion genes, ACR3 and FPS1, did not prevent this loss. At trace level concentrations (120 ppb), rapid and total arsenate removal was observed. The presence of 50 ?M phosphate reduced uptake by approximately 15% in buffer containing 80 ?M (6,000 ppb) arsenate. At trace levels of arsenate (70 ppb), the phosphate reduced the initial rate of uptake, but not the total amount removed. PHO84 mRNA levels were nearly 30 times higher in the engineered strains relative to the control strains. Uptake may no longer be a limiting factor in the engineered system and further increases should be possible by upregulating the downstream reduction and sequestration pathways. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012.",
Arsenic,2088425,Pollution and Potential Ecological Risk Assessment of Heavy Metals in a Lake Abstract: ,
Arsenic,2278034,"A Raman and infrared spectroscopic characterisation of the phosphate mineral phosphohedyphane Ca2Pb3(PO4)3Cl from the Roote mine, Nevada, USA Abstract: Phosphohedyphane Ca2Pb3(PO4)3Cl is rare Ca and Pb phosphate mineral that belongs to the apatite supergroup. We have analysed phosphohedyphane using SEM with EDX, and Raman and infrared spectroscopy. The chemical analysis shows the presence of Pb, Ca, P and Cl and the chemical formula is expressed as Ca2Pb3(PO4)3Cl. The very sharp Raman band at 975cm(-)(1) is assigned to the PO4(3-)?1 symmetric stretching mode. Raman bands noted at 1073, 1188 and 1226cm(-)(1) are to the attributed to the PO4(3-)?3 antisymmetric stretching modes. The two Raman bands at 835 and 812cm(-)(1) assigned to the AsO4(3-)?1 symmetric stretching vibration and AsO4(3-)?3 antisymmetric stretching modes prove the substitution of As for P in the structure of phosphohedyphane. A series of bands at 557, 577 and 595cm(-)(1) are attributed to the ?4 out of plane bending modes of the PO4 units. The multiplicity of bands in the ?2, ?3 and ?4 spectral regions provides evidence for the loss of symmetry of the phosphate anion in the phosphohedyphane structure. Observed bands were assigned to the stretching and bending vibrations of phosphate tetrahedra. Some Raman bands attributable to OH stretching bands were observed, indicating the presence of water and/or OH units in the structure.",
Arsenic,602763,"The ars genotype characterization of arsenic-resistant bacteria from arsenic-contaminated gold-silver mines in the Republic of Korea Abstract: The isolates were identified on the basis of ars genotype characteristics as well as arsenic oxidation/reduction analysis based on the molecular detection characterization. Diversity, pH range (4.0 to 7.0), location, and ars features were assessed for four arsenic-contaminated pond sites and six arsenic tailings located in the Duck-um mine and Myoung-bong mine areas. The presence of ars genes in the genomes of each bacterial strain was evaluated using polymerase chain reaction. Batch experiment results showed that Pseudomonas putida strains OS-3 and -18 completely oxidized 1 mM of arsenite(III) to arsenate(V) within 35Ã¢â‚¬â€œ40 h. In contrast, two arsenate-reducing bacteria isolated from mines, P. putida RS-4 and RS-5, were capable of growing aerobically in growth medium supplemented with up to 66.7 mM arsenate(V), which are significantly higher concentration than those tolerated by other arsenic-resistant bacteria. These results suggest that newly isolated indigenous arsenic-resistant bacteria may provide a better understanding of the molecular geomicrobiology and may be applied to the bioremediation of arsenic-contaminated mines in Korea. Ecologically, the redox potential plays an important role in arsenic toxicity and mobility in As-contaminated mine areas, as it facilitates the biogeochemical cycling activity of Pseudomonas sp. groups.",
Arsenic,2347634,"The novel regulations of MEF2A, CAMKK2, CALM3, and TNNI3 in ventricular hypertrophy induced by arsenic exposure in rats Abstract: Arsenic is a ubiquitous toxic compound that exists naturally in many sources such as soil, groundwater, and food; in which vast majority forms are arsenite (As(3+)) or arsenate (As(5+)). The mechanism of arsenic detoxification in humans still remains obscured. Epidemiologic studies documented that arsenic pollution caused black foot disease, cardiovascular diseases (hypertension, hypotension, cardiomyopathy), bladder cancer and skin cancer in many countries in which Taiwan is considered as high arsenic exposure country for long time ago. However, the effects of arsenic to cardiac functions still lacked of investigation while some studies mainly focus on inflammatory and cancer mechanisms. In the present study, we found cardiac hypertrophy signaling may be the most significant pathway for up regulated genes in arsenic exposed patients via bioinformatics approach. To verify our bioinformatics prediction, arsenic was fed orally to rats at different concentration based on previous studies in Taiwan. Using hemodynamic method as the main tool to measure the changes in blood pressure, left ventricular pressure and left ventricular contractility index, the findings suggest that highly exposure to arsenic lead to hypertension; elevated left ventricular diastolic pressure and alteration in cardiac contractility which are supposed to be the interaction between arsenic and cardiac nerves activity via the changing in calcium homeostasis. Collectively, based on our real-time PCR and western blot data strongly suggest that calcium homeostasis may also go through MEF2A, TNNI3, CAMKK2, CALM3 and cardiac hypertrophy relative signaling pathway.",
Arsenic,1032625,"Effect of arsenic on carbohydrate metabolism after single or repeated injection in guinea pigs Abstract: Divergent pattern in pyruvate efflux from livers perfused with As2O3 and livers of animals previously repeatedly treated with the toxicant was observed in earlier experiments (Reichl et al. 1987, 1988). Further studies of the effect of As2O3 on carbohydrate metabolism were therefore performed. Male guinea pigs received either a single dose of As2O3 10 mg.kg-1 s.c. or repeated doses of 2.5 mg.kg-1 bis in die (b.i.d.) on 5 consecutive days. One hour after the single dose or 1 h and 16 h after the last injection in the repeated treatment group the animals were sacrificed under anaesthesia. The livers were removed by a freeze-stop technique and the contents of glycogen and glycolysis intermediates were measured. In the single dose group a decrease in fructose-1,6-diphosphate and glycerol-aldehyde-3-phosphate and an increase in phosphoenol-pyruvate and pyruvate was observed. In the repeat dose, 1-h group a significant decrease in glycogen, glucose-6-phosphate, fructose-6-phosphate, glycerolaldehyde-3-phosphate, dihydroxyacetonephosphate, 2-phosphoglycerate and pyruvate was found. In the repeat dose, 16-h group the contents of glycogen, glucose-6-phosphate, pyruvate and lactate were diminished. The most prominent finding after repeated As2O3 administration was a marked depletion in total carbohydrate content. This was due mainly to depletion of glycogen.",
Arsenic,627303,"Arsenic in drinking water and pregnancy outcomes Abstract: We studied a group of women of reproductive age (15-49 years) who were chronically exposed to arsenic through drinking water to identify the pregnancy outcomes in terms of live birth, stillbirth, spontaneous abortion, and preterm birth. We compared pregnancy outcomes of exposed respondents with pregnancy outcomes of women of reproductive age (15-49 years) who were not exposed to arsenic-contaminated water. In a cross-sectional study, we matched the women in both exposed and nonexposed groups for age, socioeconomic status, education, and age at marriage. The total sample size was 192, with 96 women in each group (i.e., exposed and nonexposed). Of the respondents in the exposed group, 98% had been drinking water containing [Greater and equal to] 0.10 mg/L arsenic and 43.8% had been drinking arsenic-contaminated water for 5-10 years. Skin manifestation due to chronic arsenic exposure was present in 22.9% of the respondents. Adverse pregnancy outcomes in terms of spontaneous abortion, stillbirth, and preterm birth rates were significantly higher in the exposed group than those in the nonexposed group (p = 0.008, p = 0.046, and p = 0.018, respectively).",
Arsenic,1597353,"Bioluminescent bioreporter for assessment of arsenic contamination in water samples of India Abstract: In the present study the most efficient R-factor controlling the ars operon was selected after screening of 39 Escherichia coli isolates by minimum inhibitory concentration test (MIC) studies from water samples of different geographical locations of India. Among all, strain isolated from Hooghly River (West Bengal) was found to have maximum tolerance towards arsenic and was further used for the development of bioreporter bacteria. Cloning of the ars regulatory element along with operator-promotor and luxCDABE from Photobacteria into expression vector has been accomplished by following recombinant DNA protocols. The bioreporter sensor system developed in this study can measure the estimated range of 0.74-60 mu g of As/L and is both specific and selective for sensing bioavailable As. The constructed bacterial biosensor was further used for the determination of arsenic ion concentration in different environmental samples of India.",
Arsenic,503434,"The effect of arsenicals on ultraviolet-radiation-induced growth arrest and related signaling events in human keratinocytes Abstract: The molecular mechanisms mediating arsenic-induced carcinogenesis are not well understood. The role of confounding factors such as ultraviolet radiation (UV), add another level of complexity to the study of arsenic carcinogenesis and the cancer-risk assessment oil humans. We hypothesized that arsenicals are capable of overriding the growth arrest caused by UV treatment and may lead to selective proliferation. To test this hypothesis, a primary normal human epidermal keratinocyte (NHEK) cell culture model was used. One group was pre-exposed to UVB (100 mJ/cml) that arrested a majority (similar to 95%) of cells in G(0)VG(1) (+UV) and a second group was not exposed to UV (-UV). Treatment of cells with various arsenicals [0-12 mu M of inorganic arsenite (iAs), 0-2 mu M of methyl oxoarsine (MMAs III) and 0-3 mu M of iododimethyl arsine (DMAs III)] indicated a concentration-dependent increase in proliferation at 24 h in the order of DMAs III > MMAs III > iAs. Flow-cytometric analyses revealed differential effects on cell cycle distribution. Analysis of a battery of cell cycle proteins (cyclin D1, cdk5, PCNA, cdc25A and cdc25C) indicated exposure-specific differential expression profiles. Increased activation of JNK phosphorylation (5-10-fold) in the +UV group and the synergistic increase with methyl arsenicals suggested that JNK might be involved in cell survival and proliferative signaling. Induction of EGF levels and increased phosphorylation of the EGF receptor by arsenicals (+UV) suggested that the EGF signaling pathway might mediate arsenical-induced cell proliferation of NHEK cells. Differential activation of ERK1/2 by arsenicals (+/- UV) suggested that EGF-mediated cell proliferation by arsenicals in UV-treated NHEK cells may not involve ERK activation. Taken together, the data suggest that both UV exposure and methylation status of the arsenicals dictate the participation of key cell cycle proteins and related signaling events in arsenical-induced cell proliferation.",
Arsenic,1353643,Alteration on immune cells subpopulations and lymphocyte proliferation by arsenic exposure in infant populations Abstract: ,
Arsenic,2149125,"One-step fabrication of multifunctional composite polyurethane spider-web-like nanofibrous membrane for water purification Abstract: A stable silver-doped fly ash/polyurathene (Ag-FA/PU) nanocomposite multifunctional membrane is prepared by a facile one-step electrospinning process using fly ash particles (FAPs). Colloidal solution of PU with FAPs and Ag metal precursor was subjected to fabricate nanocomposite spider-web-like membrane using electrospinning process. Presence of N,N-dimethylformamide (solvent of PU) led to reduce silver nitrate into Ag NPs. Incorporation of Ag NPs and FAPs through electrospun PU fibers is proven through electron microscopy and spectroscopic techniques. Presence of these NPs on PU nanofibers introduces several potential physicochemical properties such as spider-web-like nano-neeting for NPs separation, enhanced absorption capacity to remove carcinogenic arsenic (As) and toxic organic dyes, and antibacterial properties with reduce bio-fouling for membrane filter application. Preliminary observations used for above-mentioned applications for water treatment showed that it will be an economically and environmentally friendly nonwoven matrix for water purification. This simple approach highlights new avenues about the utilization of one pollutant material to control other pollutants in scalable and inexpensive ways.",
Arsenic,1016185,"High exposure to arsenic from drinking water at several localities in eastern Croatia Abstract: This study investigated the relationship between arsenic concentrations in drinking water in four towns/villages in eastern Croatia and corresponding hair arsenic concentrations of residents. The mean arsenic concentrations in community drinking water samples were 0.14, 37.88, 171.60, and 611.89 microg/l. The corresponding mean concentrations of the element in hair samples of subjects residing in each of the localities were 0.07 (n=11), 0.26 (n=17), 1.74 (n=11), and 4.31 microg/g (n=23). Chronic exposures to arsenic levels estimated in three investigated locations could present a serious health threat to around 3% of Croatian population.",
Arsenic,1346724,"Sorption and desorption processes of selenium (VI) using non-living biomasses of aquatic weeds in horizontal flow Abstract: The sorption and desorption processes of Se(VI) onto non-living Eichhornia crassipes (E. crassipes) and Lemna minor (L. minor) were evaluated. Different pH values of the initial Se solution (20 ?g L?1) were tested at static conditions. At dynamic conditions of horizontal flow, biomass-packed columns (BPC) were estimated as prepared (pH 4) and unprepared (pH 6–7) and at different flow rates. The desorption process was tested using HCl (0.1 M) as the eluent. The maximum Se uptake took place at a pH of 4 for both biomasses. The lowest flow rate improves major Se removal due to the increase in contact time. The Se was desorbed from the biomass with elution efficiencies of 5 and 18 % for E. crassipes and L. minor, respectively. Nevertheless, more time was needed to increase these efficiencies and reach desaturation times. The breakthrough curves showed that unprepared E. crassipes and L. minor BPC at horizontal flow, with a flow rate of 6 and 4 mL min?1 respectively, had a biomass removal capacity of 0.135 and 0.743 ?g g?1 correspondingly. The system of E. crassipes is more efficient, suggesting an ion exchange sorption mechanism. This demonstrates that non-living E. crassipes and L. minor have the capacity to remove Se from very dilute solutions.",
Arsenic,628048,"Arsenic stimulates angiogenesis and tumorigenesis in vivo Abstract: Trivalent inorganic arsenic (arsenite, arsenic trioxide, As[III]) is currently being used to treat hematologic tumors and is being investigated for treating solid tumors. However, low concentrations of As(III) stimulate vascular cell proliferation in cell culture, although this has not been confirmed in vivo. Therefore, the hypothesis that As(III) enhances blood vessel growth (angiogenesis) and tumorigenesis was tested in two in vivo models of angiogenesis and a model of tumor growth. In the first, arsenite caused a dose-dependent increase in vessel density in a chicken chorioallantoic-membrane (CAM) assay. The threshold As(III) concentration for this response was 0.033 microM and inhibition of vessel growth was observed at concentrations greater than 1 microM. Mouse Matrigel implants were used to test the angiogenic effects of As(III) in an adult mammalian system. Mice were injected with 0.8-80 microg/kg As(III)/day over a three-week period. During the last two weeks, Matrigel plugs were placed on the abdominal wall. Low and high doses of As(III) were synergistic with fibroblast growth factor-2 (FGF-2) in increasing vessel density in the Matrigel assay, while a middle dose had no effect. To test the effects of As(III) on tumor growth, GFP-labeled B16-F10 mouse melanoma cells were implanted in nude mice, which subsequently received biweekly injections of 0.5-5.0 mg/kg As(III). Significant tumor growth and lung metastasis was seen in all animals, with the largest tumors occurring in animals treated with lower doses of As(III). These studies support the hypothesis and indicate that induction of angiogenesis, enhanced tumor growth, and metastasis are potential dose-dependent toxic side effects of arsenic therapies.",
Arsenic,627970,"Cyclooxygenase-2 induction by arsenite through the IKKbeta/NFkappaB pathway exerts an antiapoptotic effect in mouse epidermal Cl41 cells Abstract: BACKGROUND: Arsenic contamination has become a major public health concern worldwide. Epidemiologic data show that long-term arsenic exposure results in the risk of skin cancer. However, the mechanisms underlying carcinogenic effects of arsenite on skin remain to be studied. OBJECTIVES: In the present study we evaluated cyclooxygenase-2 (COX-2) expression, the signaling pathways leading to COX-2 induction, and its antiapoptotic function in the response to arsenite exposure in mouse epidermal JB6 Cl41 cells. METHODS: We used the luciferase reporter assay and Western blots to determine COX-2 induction by arsenite. We utilized dominant negative mutant, genetic knockout, gene knockdown, and gene overexpression approaches to elucidate the signaling pathway involved in COX-2 induction and its protective effect on cell apoptosis. RESULTS: The induction of COX-2 by arsenite was inhibited in Cl41 cells transfected with IKKbeta-KM, a dominant mutant inhibitor of kbeta (Ikbeta) kinase (IKKbeta), and in IKKbeta-knockout (IKKbeta(-/-)) mouse embryonic fibroblasts (MEFs). IKKbeta/nuclear factor kappaB (NFkappaB) pathway-mediated COX-2 induction exerted an antiapoptotic effect on the cells exposed to arsenite because cell apoptosis was significantly enhanced in the Cl41 cells transfected with IKKbeta-KM or COX-2 small interference RNA (siCOX-2). In addition, IKKbeta(-/-) MEFs stably transfected with COX-2 showed more resistance to arsenite-induced apoptosis compared with the same control vector-transfected cells. CONCLUSIONS: These results demonstrate that arsenite exposure can induce COX-2 expression through the IKKbeta/NFkappaB pathway, which thereby exerts an antiapoptotic effect in response to arsenite. In light of the importance of apoptosis evasion during carcinogenesis, we anticipate that COX-2 induction may be at least partially responsible for the carcinogenic effect of arsenite on skin.",
Arsenic,1597373,"Extractability and bioavailability of Pb and As in historically contaminated orchard soil: effects of compost amendments Abstract: The availability of Pb and As in an historically contaminated orchard soil, after amendment with compost and aging in the field, was determined by single-step chemical extraction with 1.0 M ammonium acetate at pH 4.8, sequential extraction using the modified BCR test, and a redworm bioassay in the laboratory. The efficiency of soil Pb extraction by ammonium acetate was greater at higher total soil Pb but was reduced by compost amendment. Conversely, the extraction efficiency of total soil As increased with compost amendment, but was not sensitive to total soil As. The redworm bioassay indicated Pb (but not As) bioavailability to be reduced by soil amendment with compost, a result consistent with the ammonium acetate extraction test but not reflected in modified BCR test. Electron microprobe studies of the orchard soil revealed Pb and As to be spatially associated in discrete particles along with phosphorus and iron.",
Arsenic,628682,"[Effect of wolfram, molybdenum, copper and arsenic on intrauterine fetal development] Abstract: Experients showed tungsten, molibdenum, copper and arsenic employed in doses producing no general toxic effect on the organism with their prolonged introduction to act adversely on the embryogenesis. Tungsten copper and arsenic were found to increase the embryonal lethality and tungsten and molebdenum to inhibit the processes of bones ossification in fetuses. The authors presume that the embryotoxic effect of the study elements is due to their direct action on the developing organism. Tungsten molibdenum and copper amass in the organism of test fetuses without being arrested in the placenta. A possible embryotoxic effect should be taken account of in chosing biogenic doses of trace elements.",
Arsenic,2088469,"Lead and other heavy metals in dust fall from single-family housing demolition Abstract: OBJECTIVE: We measured lead and other heavy metals in dust during older housing demolition and effectiveness of dust suppression. METHODS: We used American Public Housing Association Method 502 and U.S. Environmental Protection Agency Methods SW3050B and SW6020 at 97 single-family housing demolition events with intermittent (or no) use of water to suppress dust at perimeter, non-perimeter, and locations without demolition, with nested mixed modeling and tobit modeling with left censoring. RESULTS: The geometric mean (GM) lead dust fall during demolition was 6.01 micrograms of lead per square foot per hour (?g Pb/ft(2)/hour). GM lead dust fall was 14.18 ?g Pb/ft(2)/hour without dust suppression, but declined to 5.48 ?g Pb/ft(2)/hour (p=0.057) when buildings and debris were wetted. Significant predictors included distance, wind direction, and main street location. At 400 feet, lead dust fall was not significantly different from background. GM lead concentration at demolition (2,406 parts per million [ppm]) was significantly greater than background (GM=579 ppm, p=0.05). Arsenic, chromium, copper, iron, and manganese demolition dust fall was significantly higher than background (p<0.001). Demolition of approximately 400 old housing units elsewhere with more dust suppression was only 0.25 ?g Pb/ft(2)/hour. CONCLUSIONS: Lead dust suppression is feasible and important in single-family housing demolition where distances between houses are smaller and community exposures are higher. Neighbor notification should be expanded to at least 400 feet away from single-family housing demolition, not just adjacent properties. Further research is needed on effects of distance, potential water contamination, occupational exposures, and water application.",
Arsenic,710893,"The defensive effect of benfotiamine in sodium arsenite-induced experimental vascular endothelial dysfunction Abstract: The present study has been designed to investigate the effect of benfotiamine, a thiamine derivative, in sodium arsenite-induced vascular endothelial dysfunction (VED) in rats. Sodium arsenite (1.5 mg(-1) kg(-1) day(-1) i.p., 2 weeks) was administered in rats to produce VED. The development of VED was assessed by employing isolated aortic ring preparation and estimating the serum and aortic concentrations of nitrite/nitrate. Further, the integrity of vascular endothelium in thoracic aorta was assessed by scanning electron microscopy. Moreover, the oxidative stress was assessed by estimating serum thiobarbituric acid reactive substances (TBARS) and aortic superoxide anion generation. The administration of sodium arsenite markedly produced VED by attenuating acetylcholine-induced endothelium-dependent relaxation, decreasing serum and aortic concentrations of nitrite/nitrate, and impairing the integrity of vascular endothelium. Further, sodium arsenite produced oxidative stress by increasing serum TBARS and aortic superoxide generation. The treatment with benfotiamine (25, 50, and 100 mg(-1) kg(-1) day(-1) p.o.) or atorvastatin (30 mg(-1) kg(-1) day(-1) p.o., a standard agent) prevented sodium arsenite-induced VED and oxidative stress. However, the beneficial effects of benfotiamine in preventing the sodium arsenite-induced VED were attenuated by co-administration with N-omega-nitro-L: -arginine methyl ester (L: -NAME) (25 mg(-1) kg(-1) day(-1), i.p.), an inhibitor of NOS. Thus, it may be concluded that benfotiamine reduces oxidative stress and activates endothelial nitric oxide synthase to enhance the generation and bioavailability of NO and subsequently improves the integrity of vascular endothelium to prevent sodium arsenite-induced experimental VED.",
Arsenic,1337305,"Heavy metals concentrations in fish and shellfish from eastern Mediterranean Sea: Consumption advisories Abstract: The present study evaluate concentrations of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), manganese (Mn), nickel (Ni), vanadium (V) and zinc (Zn) in fish and shellfish from the Gulf of Catania. Heavy metal analysis was carried on with an ICP-MS, and consumption rates advisory for minimizing chronic systemic and non cancer endpoints in child and adults have been estimated. Among metals investigated, only Cd and Pb have a limit set by European Community for human consumption, and the thresholds were not been exceeded in analyzed species. The As, toxic in its inorganic form, have not a regulatory limit yet, but the Environmental Protection Agency and the World Health Organization provide a reference dose, a cancer slope factor and a tolerable intake, applicable in the risk factors assessment. Arsenic target hazard quotient (THQ) values, suggest that human should minimizing meals/week of analyzed species to avoid deleterious effect during lifetime, furthermore, with As cancer risk assessment, for most of the fish, the risk for cancer is greater than the acceptable lifetime risk of 10(-5). Our results give important finding about the consumption limits on certain metals, especially for As, all for minimizing potential health risks in population.",
Arsenic,1031099,"Stress-induced proteins in aortic smooth muscle cells and aorta of hypertensive rats Abstract: The current studies were performed to determine whether vascular smooth muscle cells produce stress-induced proteins when subjected to experimental hypertension. Two-dimensional gel electrophoresis was used to analyze labeled proteins in cultured cells in response to either heat shock or arsenite treatment. The major heat shock proteins (HSPs) induced had molecular masses of 70, 90, and 110 kDa. Arsenite treatment produced a similar response with the additional induction of a 30-kDa protein. In vitro translations of total RNA from heat-shocked cells, and RNA blot hybridization using HSP 70 cDNA suggested that HSP 70 induction was transcriptionally regulated. Treatment of cells with norepinephrine or angiotensin II induced cellular hypertrophy without eliciting HSPs. In vitro translation of aortic RNA from rats rendered hypertensive by administration of deoxycorticosterone and a high salt intake also did not reveal HSP induction. The absence of HSP induction using an in vivo model of hypertension suggests that those proteins may not be required to mediate the vascular response to experimental hypertension.",
Arsenic,1024614,"Arsenic in Oregon community water systems: demography matters Abstract: Recently, the maximum contaminate level (MCL) for arsenic was lowered to 10 microg/L in community water systems (CWS) throughout the United States. In this study, CWS in Oregon were assessed for the occurrence and magnitude of arsenic &gt;10 microg/L between the effective and compliance dates for the new MCL. Ten CWS, with a combined population of 49,395, met the criteria for this study. Arsenic levels above the new MCL ranged from 11-25 microg/L. The demographic characteristics of these systems were queried and considered in the context of risk, exposure and outreach. A disproportionate percent of residents in affected CWS were of Hispanic origin (35%) compared to the statewide average (8%). Residents in these CWS had a lower median household income (20% less than the statewide average), a lower median age (32.5 vs. 36.3) and a higher percent of a second language spoken in the home besides English (34.6% vs. 12.1%) compared to the statewide census. These community characteristics have implications for exposure, risk and outreach associated with the occurrence of arsenic in drinking water. Consequently, demographic parameters are informative for risk management and communication and ultimately, beneficial to the affected public.",
Arsenic,2343541,"Yeast reveals unexpected roles and regulatory features of aquaporins and aquaglyceroporins Abstract: Background: The yeast Saccharomyces cerevisiae provides unique opportunities to study roles and regulation of aqua/glyceroporins using frontline tools of genetics and genomics as well as molecular cell and systems biology. Scope of review: S. cerevisiae has two similar orthodox aquaporins. Based on phenotypes mediated by gene deletion or overexpression as well as on their expression pattern, the yeast aquaporins play important roles in key aspects of yeast biology: establishment of freeze tolerance, during spore formation as well as determination of cell surface properties for substrate adhesion and colony formation. Exactly how the aquaporins perform those roles and the mechanisms that regulate their function under such conditions remain to be elucidated. S. cerevisiae also has two different aquaglyceroporins. While the role of one of them, Yfl054c, remains to be determined, Fps1 plays critical roles in osmoregulation by controlling the accumulation of the osmolyte glycerol. Fpsl communicates with two osmo-sensing MAPK signalling pathways to perform its functions but the details of Fps1 regulation remain to be determined. <br> <br>Major conclusions: Several phenotypes associated with aqua/glyceroporin function in yeasts have been established. However, how water and glycerol transport contribute to the observed effects is not understood in detail. Also many of the basic principles of regulation of yeast aqua/glyceroporins remain to be elucidated. <br> <br>General significance: Studying the yeast aquaporins and aquaglyceroporins offers rich insight into the life style, evolution and adaptive responses of yeast and rewards us with discoveries of unexpected roles and regulatory mechanisms of members of this ancient protein family. This article is part of a Special Issue entitled Aquaporins. (c) 2013 Elsevier B.V. All rights reserved.",
Arsenic,1936060,"Identification of a possible respiratory arsenate reductase in Denitrovibrio acetiphilus, a member of the phylum Deferribacteres Abstract: Denitrovibrio acetiphilus N2460(T) is one of the few members of the phylum Deferribacteres with a sequenced genome. N2460(T) was capable of growing with dimethyl sulfoxide, selenate, or arsenate provided as a terminal electron acceptor, and we identified 15 genes that could possibly encode respiratory reductases for these compounds. The protein encoded by one of these genes, YP_003504839, clustered with respiratory arsenate reductases on a phylogenetic tree. Transcription of the gene for YP_003504839, Dacet_2121, was highly induced when arsenate was provided as a terminal electron acceptor. Dacet_2121 exists in a possible operon that is distinct from the previously characterized respiratory arsenate reductase operon in Shewanella sp. ANA-3.",
Arsenic,1030160,"Regulation of glucose uptake by stressed cells Abstract: Lactate production by BHK cells is stimulated by arsenite, azide, or by infection with Semliki Forest virus (SFV). In the case of arsenite or SFV infection, the increase correlates approximately with the increase in glucose transport as measured by uptake of [3H] deoxy glucose (dGlc); in the case of azide, the increase in lactate production exceeds that of glucose transport. Hence glucose utilization by BHK cells and its stimulation by anaerobic and other types of cellular stress is controlled at least in part at the level of glucose transport. The glucose uptake by BHK cells is also stimulated by serum and by glucose deprivation. In these circumstances, as with arsenite, stimulation is reversible, with t1/2 of 1-2 hours; stimulation is compatible with a translocation of the glucose transporter protein between an intracellular site and the plasma membrane (shown here for serum and previously for arsenite). The surface binding and rate of internalization of [125I]-labelled transferrin and [125I] alpha 2-macroglobulin was studied to determine whether changes in glucose transport are accompanied by changes in the surface concentration or rate of internalization of membrane proteins. The findings indicate that changes in glucose transport do not reflect a consistent and general redistribution of membrane receptors. Taken together, the results are compatible with the proposal that BHK cells exposed to stimuli like insulin or serum, or to stresses like arsenite, azide, SFV infection, or deprivation of glucose, respond in the same manner: namely, by an increased capacity to transport glucose brought about by reversible and specific translocation of the transporter protein from an (inactive) intracellular site to the plasma membrane.",1
Arsenic,2064198,"A study on As, Cu, Pb and Zn (bio)availability in an abandoned mine area (São Domingos, Portugal) using chemical and ecotoxicological tools Abstract: The aim of this study was to relate the results obtained by chemical methods, used to assess environmental (bio)availability, with the ecotoxic response and bioaccumulation of trace elements (TE) by the earthworm Eisenia fetida exposed to field-contaminated, metal-polluted soils from a sulphide mine. The extracting solution 0.5 M NH4CH3COO, 0.5 M CH3COOH and 0.02 M EDTA (pH 4.7), was able to predict environmental bioavailability of TE to E. fetida. However, the toxicological bioavailability could not be predicted from the results of the chemical extractions or from the bioaccumulation results: E. fetida reproduction was higher in soils where environmental bioavailability of TE and bioaccumulation values were also higher. In this study, the toxic response of the organism seemed to be more influenced by the overall nutritional status of the soil (e.g. pH, organic matter, plant nutrient availability and cation exchange capacity) than by its TE contamination. In the case of anthropogenic multi-contaminated sites, the different soil characteristics exert an important and confounding influence in the toxic response and the relationship between different bioavailable fractions cannot be easily established, emphasising the need to combine results from chemical methods with those from bioassays when evaluating the bioavailability of TE in these soils.",
Arsenic,2343487,"A market basket survey of As, Zn and Se in rice imports in Qatar: Health implications Abstract: Qatar is dependent on importation of rice, its staple dish, and is therefore susceptible to compromises of food quality in the global market. This market basket study assesses potential health risks of As exposure from rice consumption in Qatar and examines its contribution to the recommended nutritional intakes (RNI) for Zn and Se. Fifty-six rice types and 12 products sold in Qatar were analyzed by ICP/MS. Mean concentrations and ranges were 96.2±54.1?g/kg (9.76-258?g/kg) for As; 12.5±5.35mg/kg (2.79-29.9mg/kg) for Zn and 103±113?g/kg (&lt;5.94-422?g/kg) for Se. Calculated risk quotient shows rice consumption in Qatar is not a significant route of As exposure but can contribute up to 100% and 50% of the RNI for Se and Zn, respectively. Results indicate that children in Qatar may be at elevated risk of arsenic exposure from rice-based infant cereals but more data is needed to obtain a definitive assessment.",
Arsenic,1597346,"Identification of antimony- and arsenic-oxidizing bacteria associated with antimony mine tailing Abstract: Antimony (Sb) is a naturally occurring toxic element commonly associated with arsenic (As) in the environment and both elements have similar chemistry and toxicity. Increasing numbers of studies have focused on microbial As transformations, while microbial Sb interactions are still not well understood. To gain insight into microbial roles in the geochemical cycling of Sb and As, soils from Sb mine tailing were examined for the presence of Sb- and As-oxidizing bacteria. After aerobic enrichment culturing with As(III) (10 mM) or Sb(III) (100 ?M), pure cultures of Pseudomonas- and Stenotrophomonas-related isolates with Sb(III) oxidation activities and a Sinorhizobium-related isolate capable of As(III) oxidation were obtained. The As(III)-oxidizing Sinorhizobium isolate possessed the aerobic arsenite oxidase gene (aioA), the expression of which was induced in the presence of As(III) or Sb(III). However, no Sb(III) oxidation activity was detected from the Sinorhizobium-related isolate, suggesting the involvement of different mechanisms for Sb and As oxidation. These results demonstrate that indigenous microorganisms associated with Sb mine soils are capable of Sb and As oxidation, and potentially contribute to the speciation and mobility of Sb and As in situ.",
Arsenic,1031762,"Heat shock and arsenite increase expression of the multidrug resistance (MDR1) gene in human renal carcinoma cells Abstract: The multidrug transporter, initially identified as a multidrug efflux pump responsible for resistance of cultured cells to natural product cytotoxic drugs, is normally expressed on the apical membranes of excretory epithelial cells in the liver, kidney, and intestine. This localization suggests that the multidrug transporter may have a normal physiological role in transporting cytotoxic compounds or metabolites. In the liver, hepatectomy or treatment with chemical carcinogens increases expression of the MDR1 gene which encodes the multidrug transporter. To evaluate conditions which increase MDR1 gene expression, we have investigated the induction of the MDR1 gene by physical and chemical environmental insults in the renal adenocarcinoma cell line HTB-46. There are two strong heat shock consensus elements in the major MDR1 gene promoter. Exposure of HTB-46 cells to heat shock, sodium arsenite, or cadmium chloride led to a 7- to 8-fold increase in MDR1 mRNA levels. MDR1 RNA levels did not change following glucose starvation or treatment with 2-deoxyglucose and the calcium ionophore A23187, conditions which are known to activate the expression of another family of stress proteins, the glucose-regulated proteins. The levels of the multidrug transporter, P-glycoprotein, as measured by immunoprecipitation, were also increased after heat shock and sodium arsenite treatment. This increase in the level of the multidrug transporter in HTB-46 cells correlated with a transient increase in resistance to vinblastine following heat shock and arsenite treatment. These results suggest that the MDR1 gene is regulatable by environmental stress.",
Arsenic,2343559,"Arsenic dynamics in the rhizosphere and its sequestration on rice roots as affected by root oxidation Abstract: A pot experiment was conducted to investigate the effects of root oxidation on arsenic (As) dynamics in the rhizosphere and As sequestration on rice roots. There were significant differences (P &lt; 0.05) in pH values between rhizosphere and non-rhizosphere soils, with pH 5.68-6.16 in the rhizosphere and 6.30-6.37 in non-rhizosphere soils as well as differences in redox potentials (P &lt; 0.05). Percentage arsenite was lower (4%-16%) in rhizosphere soil solutions from rice genotypes with higher radial oxygen loss (ROL) compared with genotypes with lower ROL (P &lt; 0.05). Arsenic concentrations in iron plaque and rice straw were significantly negatively correlated (R = -0.60, P &lt; 0.05). Genotypes with higher ROL (TD71 and Yinjingruanzhan) had significantly (P &lt; 0.001) lower total As in rice grains (1.35 and 0.96 mg/kg, respectively) compared with genotypes with lower ROL (IAPAR9, 1.68 mg/kg; Nanyangzhan 2.24 mg/kg) in the As treatment, as well as lower inorganic As (P &lt; 0.05). The present study showed that genotypes with higher ROL could oxidize more arsenite in rhizosphere soils, and induce more Fe plaque formation, which subsequently sequestered more As. This reduced As uptake in aboveground plant tissues and also reduced inorganic As accumulation in rice grains. The study has contributed to further understanding the mechanisms whereby ROL influences As uptake and accumulation in rice.",
Arsenic,1017057,"Glutathione-conjugated arsenics in the potential hepato-enteric circulation in rats Abstract: The metabolic pathways for arsenic were precisely studied by determining the metabolic balance and chemical species of arsenic to gain an insight into the mechanisms underlying the animal species difference in the metabolism and preferential accumulation of arsenic in red blood cells (RBCs) in rats. Male Wistar rats were injected intravenously with a single dose of arsenite (iAs(III)) at 2.0 mg of As/kg of body weight, and then the time-dependent changes in the concentrations of arsenic in organs and body fluids were determined. Furthermore, arsenic in the bile was analyzed on anion and cation exchange columns by high-performance liquid chromatography-inductively coupled argon plasma mass spectrometry (HPLC-ICP MS). The metabolic balance and speciation studies revealed that arsenic is potentially transferred to the hepato-enteric circulation through excretion from the liver in a form conjugated with glutathione (GSH). iAs(III) is methylated to mono (MMA)- and dimethylated (DMA) arsenics in the liver during circulation in the conjugated form [iAs(III)(GS)(3)], and a part of MMA is excreted into the bile in the forms of MMA(III) and MMA(V), the former being mostly in the conjugated form [CH(3)As(III)(GS)(2)], and the latter being in the nonconjugated free form. DMA(III) and DMA(V) were not detected in the bile. In the urine, arsenic was detected in the forms of iAs(III), arsenate, MMA(V), and DMA(V), iAs(III) being the major arsenic in the first 6-h-urine, and DMA(V) being increased in the second 6-h-urine. The present metabolic balance and speciation study suggests that iAs(III) is methylated in the liver during its hepato-enteric circulation through the formation of the GSH-cojugated form [iAs(III)(GS)(3)], and MMA(III) and MMA(V) are partly excreted into the bile, the former being in the conjugated form [CH(3)As(III)(GS)(2)]. DMA is not excreted into the bile but into the bloodstream, accumulating in RBCs, and then excreted into the urine mostly in the form of DMA(V) in rats.",
Arsenic,1579277,"As(V) retention on soils and forest by-products and other waste materials Abstract: As(V) retention capacity is determined by means of adsorption/desorption trials performed for coarse and fine ground mussel shell, forest and vineyard soils with or without fine shell, pine wood ash, oak wood ash, pine sawdust and slate-processing fines. Pine ash shows the highest arsenic retention potential (with &gt;97 % adsorption and ?1 % desorption), followed by shell-amended forest soil (adsorption between 96 and 92 %), by un-amended forest soil (adsorption between 98 and 86 %) and by the amended vineyard soil (adsorption between 92 and 75 %). Sawdust is the material with the lowest arsenic retention capacity in most cases, with un-amended vineyard soil also showing poor results. In the case of oak ash, As(V) percentage adsorption becomes higher with increasing added arsenic concentrations, while this increase in added arsenic causes lower percentage adsorption in the case of slate fines. Regarding adsorption ability, As(V) adsorption data were fitted to Freundlich and Langmuir models, showing good fitting, with pine ash and shell-amended forest soil having the highest K F values. In view of that, mussel shell amendment would be useful to increase arsenic retention on forest and vineyard soils, while pine ash could be used to retain arsenic even from wastewaters.",
Arsenic,1024752,"Taurine, a conditionally essential amino acid, ameliorates arsenic-induced cytotoxicity in murine hepatocytes Abstract: Arsenic is a potent environmental toxin. Present study has been designed to evaluate the protective role of taurine (2-aminoethanesulfonic acid) against arsenic induced cytotoxicity in murine hepatocytes. Sodium arsenite (NaAsO(2)) was chosen as the source of arsenic. Incubation of hepatocytes with the toxin (1 mM) for 2 h reduced the cell viability as well as intra-cellular antioxidant power. Increased activities of alanine transaminase (ALT) and alkaline phosphatase (ALP) due to toxin exposure confirmed membrane damage. Toxin treatment caused reduction in the activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx). In addition, the same treatment reduced the level of glutathione (GSH), elevated the level of oxidized glutathione (GSSG) and increased the extent of lipid peroxidation. Incubation of hepatocytes with taurine, both prior to and in combination with NaAsO(2), attenuated the extent of lipid peroxidation and enhanced the activities of enzymatic as well as non enzymatic antioxidants. Besides, taurine administration normalized the arsenic-induced enhanced levels of the marker enzymes ALT and ALP in hepatocytes. The cytoprotective activity of taurine against arsenic poisoning was found to be comparable to that of a known antioxidant, vitamin C. Combining all, the results suggest that taurine protects mouse hepatocytes against arsenic induced cytotoxicity.",
Arsenic,1936100,"Characterization of european ancestry nonalcoholic fatty liver disease-associated variants in individuals of african and hispanic descent Abstract: Nonalcoholic fatty liver disease (NAFLD) is an obesity-related condition affecting over 50% of individuals in some populations and is expected to become the number one cause of liver disease worldwide by 2020. Common, robustly associated genetic variants in/near five genes were identified for hepatic steatosis, a quantifiable component of NAFLD, in European ancestry individuals. Here we tested whether these variants were associated with hepatic steatosis in African- and/or Hispanic-Americans and fine-mapped the observed association signals. We measured hepatic steatosis using computed tomography in five African American (n?=?3,124) and one Hispanic American (n?=?849) cohorts. All analyses controlled for variation in age, age(2) , gender, alcoholic drinks, and population substructure. Heritability of hepatic steatosis was estimated in three cohorts. Variants in/near PNPLA3, NCAN, LYPLAL1, GCKR, and PPP1R3B were tested for association with hepatic steatosis using a regression framework in each cohort and meta-analyzed. Fine-mapping across African American cohorts was conducted using meta-analysis. African- and Hispanic-American cohorts were 33.9/37.5% male, with average age of 58.6/42.6 years and body mass index of 31.8/28.9 kg/m(2) , respectively. Hepatic steatosis was 0.20-0.34 heritable in African- and Hispanic-American families (P?&lt;?0.02 in each cohort). Variants in or near PNPLA3, NCAN, GCKR, PPP1R3B in African Americans and PNPLA3 and PPP1R3B in Hispanic Americans were significantly associated with hepatic steatosis; however, allele frequency and effect size varied across ancestries. Fine-mapping in African Americans highlighted missense variants at PNPLA3 and GCKR and redefined the association region at LYPLAL1. Conclusion: Multiple genetic variants are associated with hepatic steatosis across ancestries. This explains a substantial proportion of the genetic predisposition in African- and Hispanic-Americans. Missense variants in PNPLA3 and GCKR are likely functional across multiple ancestries. (Hepatology 2013;53:966-975).",
Arsenic,2215760,"Diversity and abundance of the arsenite oxidase gene aioA in geothermal areas of Tengchong, Yunnan, China Abstract: A total of 12 samples were collected from the Tengchong geothermal areas of Yunnan, China, with the goal to assess the arsenite (AsIII) oxidation potential of the extant microbial communities as inferred by the abundance and diversity of the AsIII oxidase large subunit gene aioA relative to geochemical context. Arsenic concentrations were higher (on average 251.68 ?g/L) in neutral or alkaline springs than in acidic springs (on average 30.88 ?g/L). aioA abundance ranged from 1.63 × 10(1) to 7.08 × 10(3) per ng of DNA and positively correlated with sulfide and the ratios of arsenate (AsV):total dissolved arsenic (AsTot). Based on qPCR estimates of bacterial and archaeal 16S rRNA gene abundance, aioA-harboring organisms comprised as much as ~15 % of the total community. Phylogenetically, the major aioA sequences (270 total) in the acidic hot springs (pH 3.3-4.4) were affiliated with Aquificales and Rhizobiales, while those in neutral or alkaline springs (pH 6.6-9.1) were inferred to be primarily bacteria related to Thermales and Burkholderiales. Interestingly, aioA abundance at one site greatly exceeded bacterial 16S rRNA gene abundance, suggesting these aioA genes were archaeal even though phylogenetically these aioA sequences were most similar to the Aquificales. In summary, this study described novel aioA sequences in geothermal features geographically far removed from those in the heavily studied Yellowstone geothermal complex.",
Arsenic,1597397,"Glutathione analogs in prokaryotes Abstract: Background: Oxygen is both essential and toxic to all forms of aerobic life and the chemical versatility and reactivity of thiols play a key role in both aspects. Cysteine thiol groups have key catalytic functions in enzymes but are readily damaged by reactive oxygen species (ROS). Low-molecular-weight thiols provide protective buffers against the hazards of ROS toxicity. Glutathione is the small protective thiol in nearly all eukaryotes but in prokaryotes the situation is far more complex. <br> <br>Scope of review: This review provides an introduction to the diversity of low-molecular-weight thiol protective systems in bacteria. The topics covered include the limitations of cysteine as a protector, the multiple origins and distribution of glutathione biosynthesis, mycothiol biosynthesis and function in Actinobacteria, recent discoveries involving bacillithiol found in Firmicutes, new insights on the biosynthesis and distribution of ergothioneine, and the potential protective roles played by coenzyme A and other thiols. <br> <br>Major conclusions: Bacteria have evolved a diverse collection of low-molecular-weight protective thiols to deal with oxygen toxicity and environmental challenges. Our understanding of how many of these thiols are produced and utilized is still at an early stage. <br> <br>General significance: Extensive diversity existed among prokaryotes prior to evolution of the cyanobacteria and the development of an oxidizing atmosphere. Bacteria that managed to adapt to life under oxygen evolved, or acquired, the ability to produce a variety of small thiols for protection against the hazards of aerobic metabolism. Many pathogenic prokaryotes depend upon novel thiol protection systems that may provide targets for new antibacterial agents. This article is part of a Special Issue entitled Cellular functions of glutathione. (c) 2012 Elsevier B.V. All rights reserved.",
Arsenic,1020749,"Use of near-infrared spectroscopy for determining the total arsenic content in prostrate amaranth Abstract: The potential of near infrared spectroscopy (NIRS) for determining the total arsenic (As) content in the prostrate amaranth (Amaranthus blitoides S. Watson) was assessed. Seventy-four samples belonging to this species, were harvested at different maturity stages along the polluted area, and then were scanned by NIRS. Their As reference values were obtained by atomic absorption spectrometry and they were regressed against different spectral transformations using modified partial least square (MPLS) regression. First derivative transformation equation of the raw optical data, previously standardized by standard normal variate (SNV) and De-trending (DT) transformations, resulted in a coefficient of determination (r(2)) in the external validation of 0.63, indicative of equations that can be used for a correct separation of the samples into low, medium and high groups. The standard deviation to standard error of prediction ratio (RPD) and range to standard error of prediction ratio (RER) for the first derivative equation were similar to those obtained for other trace metal calibrations reported in NIRS reflectance. Major cell components such as chlorophyll, lipids, starch and proteins were used by MPLS for modeling the equations. The use of NIRS for the determination of the As content in A. blitoides plants offers an important saving of time and cost of analysis.",
Arsenic,1016244,"Enhanced contractility of vascular smooth muscle after brief exposure to arsenate Abstract: Epidemiological studies indicate that arsenic exposure induces hypertension. We hypothesized that arsenate exposure modulates the contractility of vascular smooth muscle through the stress response. Intraperitoneal injection of sodium arsenate (15mg/kg) 16h before increased not only the blood pressure of rats but also the pressor response to preganglionic nerve stimulation (2 and 16Hz) or to bolus injection of vasopressin or phenylephrine in pithed rats as compared with the control rats. Exposure of rat aortic rings to 4mM sodium arsenate for 60min enhanced the contractile responses to KCl or phenylephrine as well as the HSP 70 expression 8h later, but did not affect the relaxation responses to acetylcholine, histamine, or sodium nitroprusside. These results suggest that brief exposure to arsenate is associated with enhanced contractility of vascular smooth muscle through the stress response.",
Arsenic,1797762,James Marsh and the poison panic Abstract: ,
Arsenic,1378293,"Subcytotoxic Inorganic Arsenite Targets Mitochondria In HK-2 Human Proximal Tubular Cells: Implications On Mechanism Of Cell Death Abstract: The kidney is a known target organ for arsenic (As) and is critical for both As biotransformation and elimination. Previous studies have demonstrated that at high doses (ppm) inorganic As (arsenate) is toxic to mitochondria primarily by affecting cellular respiration. However the effect of inorganic As on mitochondria after low level exposures is not known, particularly in the kidney. Thus the mitochondrial toxicity of low level inorganic arsenite was investigated in a human proximal tubular cell line, HK-2. Subcytotoxic concentrations of arsenite (1-10 ?M) were found to affect MTT processing by mitochondria in the HK-2 cells. Mitochondrial injury was further assessed by examining the alteration of the mitochondrial membrane potential using MitoTracker Red, a mitochondrion selective dye. In a subset of cells, subcytotoxic arsenite led to mitochondrial membrane depolarization, which could subsequently lead to permeability transition and apoptosis. Subcytotoxic arsenite also induced translocation of phosphatidylserine to the outer layer of the plasma membrane, indicative of apoptosis. To confirm whether subcytotoxic arsenite induces cellular and/or mitochondrial morphological alterations consistent with apoptotic cell death, HK-2 cells were evaluated with both light and transmission electron microscopy. Classic morphological changes indicative of apoptosis were not observed at either the light microscopic nor the electron microscopic level with subcytotoxic arsenite exposures; however, evidence of necrotic changes in cytoplasmic structure and morphology, particularly in the mitochondria, were apparent. Therefore, based on the externalization of phosphatidylserine, HK-2 cells appear to initiate apoptosis following subcytotoxic arsenite insult, but based on the morphological changes seen, fail to complete apoptosis and undergo necrosis instead. Subcytotoxic arsenite can be sufficiently toxic to mitochondria that they lose their ability to keep the cell on course for apoptotic cell death.",
Arsenic,1509349,"Spatiotemporal distribution of airborne elements monitored with the moss bags technique in the Greater Thriasion Plain, Attica, Greece Abstract: The well-known moss bags technique was applied in the heavily polluted Thriasion Plain region, Attica, Greece, in order to study the spatiotemporal distribution, in the atmosphere, of the following 32 elements: Na, Al, Cl, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni, Co, Zn, As, Se, Br, Sr, Mo, Sb, I, Ba, La, Ce, Sm, Tb, Dy, Yb, Hf, Ta, Hg, Th, and U. The moss bags were constituted of Sphagnum girgensohnii materials. The bags were exposed to ambient air in a network of 12 monitoring stations scattered throughout the monitoring area. In order to explore the temporal variation of the pollutants, four sets of moss bags were exposed for 3, 6, 9, and 12 months. Instrumental neutral activation analysis was used for the determinations of the elements. The data were analyzed using the Pearson correlations, the partial redundancy analysis, and the biplot statistical methods. Some pairs of elements were highly correlated indicating a probable common source of origin. The levels of the measured pollutants were unevenly distributed throughout the area and different pollutants exhibited different spatial patterns. In general, higher loads were observed in the stations close to and within the industrial zone. Most of the measured elements (e.g., Al, Ca, Ni, I, Zn, Cr, and As) exhibited a monotonic accumulation trend over time. Some elements exhibited different dynamics. The elements Mn, Mo, and Hg showed a decreasing trend, probably due to leaching and/or volatilization processes over time. Na and Br initially showed an increasing trend during the winter and early spring periods but decreased drastically during the late warm period. The results further suggest that the moss bags technique would be considered valuable for the majority of elements but should be used with caution in the cases of elements vulnerable to leaching and/or volatilization. It also suggests that the timing and the duration of the exposure of moss materials should be considered in the interpretation of the results.",
Arsenic,2347806,"Comparison of polyamide nanofiltration and low-pressure reverse osmosis membranes on As(III) rejection under various operational conditions Abstract: A nanofiltration (NF) membrane and a low-pressure reverse osmosis (LPRO) membrane both with aromatic polyamide selective layer from the same manufacturer were employed for the comparison of their performances in terms of As(III) rejection and filtration flux under a variety of operational conditions. In addition to the smaller membrane pore size, the LPRO membrane possesses much more dissociable functional groups than the NF membrane. When the feed pH was below the pKa(1) value (922) of H3AsO3, for which the steric hindrance is the only rejection mechanism, the removal efficiencies by NF and LPRO were about 10% and 65%, respectively. When the feed pH was higher, for which electrostatic effect began to take effect, the removal efficiencies could reach 40% and 90% for NF and LPRO, respectively. The rejection performance of LPRO was marginally affected by the feed As(III) concentration or ionic strength, although ionic strength had a strong effect on the filtration flux. In contrast, feed As(III) concentration and ionic strength had little effect on the filtration flux but great influence on the As(III) rejection performance of NF. The filtration flux was enhanced with the increase of transmembrane pressure for either NF or LPRO. The NF model could predict the general trend of the effects of the filtration flux, the feed water chemistry and its own concentration on As(III) rejection ratio by the NF membrane, but the rejection ratios were over-predicted.",
Arsenic,8339,"Arsenic exposure, smoking, and respiratory cancer in copper smelter workers Abstract: A report by Lee and Fraumeni in 1969 linked exposure to arsenic and other contaminants to a threefold excess of respiratory cancer among 8,047 employees at the Anaconda copper smelter. We established vital status through December 1977 for a sample of 1,800 men from the original cohort. Average arsenic concentrations were estimated for each smelter department based on industrial hygiene measurements made from 1943 to 1965. Departments with similar concentrations were combined into four categories of exposure: 1) low (less than 100 micrograms/m3), 2) medium (100-499 micrograms/m3), 3) high (500-4,999 micrograms/m3) and 4) very high (greater than or equal to 5,000 micrograms/m3). Three indices of individual arsenic exposure were developed: time-weighted average, 30-day ceiling, and cumulative. Exposures to sulfur dioxide and asbestos were also examined. Smoking habits were obtained by questionnaire. Mortality was compared to that of men in the State of Montana using the modified lifetable method. A clear dose-response relationship between arsenic exposure and respiratory cancer was demonstrated. Men in the highest exposure category had a sevenfold excess. Those in the low and medium categories had a risk close to that expected. Ceiling arsenic exposure appeared to be more important than did time-weighted average exposure. Sulfur dioxide and asbestos did not appear to be important in the excess of respiratory cancer, although sulfur dioxide and arsenic exposures could not be separated completely. Smoking did not appear to be as important as arsenic exposure. Our findings suggest that had men worked only in departments with low or medium arsenic exposures (i.e., less than 500 micrograms/m3) there would have been little excess respiratory cancer. Since the estimates of arsenic exposure were based on department averages rather than on concentrations for individual jobs, these results must be interpreted with caution.",
Arsenic,1337501,"Arsenic activates endothelin-1 Gi protein-coupled receptor signaling to inhibit stem cell differentiation in adipogenesis Abstract: Dysfunctional lipid and glucose metabolism contribute to metabolic syndrome; a major public health concern that enhances cardiovascular disease risk. Arsenic (As(III)) exposure may increase metabolic syndrome and cardiovascular disease risk by impairing adipose tissue differentiation, function, and insulin sensitivity through pathogenic mechanisms that remain unclear. We hypothesized that As(III) signals through the Pertussis toxin (Ptx) sensitive, Gi protein-coupled (GPCR) to impair adipogenesis, as previously demonstrated for its stimulation of vascular oxidant generation, angiogenesis, and remodeling. Since both As(III) and GPCR ligands inhibit progenitor cell differentiation into adipocytes, we investigated the hypothesis in an model of low passage human mesenchymal stem cells (hMSC). As(III) (0.1-1.0 ?M) suppressed dexamethasone/insulin-induced hMSC adipogenesis, as indicated by: decreased transcriptional promoters of differentiation; decreased fat droplet formation; and decreased expression of differentiated adipocyte markers, such as adiponectin (ADIPOQ) and perilipin (PLIN1). Pre-incubating hMSC with Ptx prevented 90% of the suppressive effect of As(III). Selective competitive antagonists of Gi-coupled endothelin-1 type A and B receptors were approximately 60% effective in blocking As(III) inhibition and combination of antagonists to both receptors were 85% effective. In contrast, antagonists to the sphingosine-1-phosphate type 1 receptor (previously shown to mediate As(III) vascular effects) or the angiotensin II type 1 receptor were ineffective in blocking As(III) effects. These studies suggest a majority of arsenic-inhibited adipocyte differentiation and metabolism requires endothelin-1 GPCRs and that As(III) effects on GPCR signaling are tissue and context specific. This may represent a significant mechanism for the contribution of arsenic exposure to increased metabolic and cardiovascular diseases.",
Arsenic,2298713,"Metal bioaccumulation in common carp and rudd from the Topolnitsa reservoir, Bulgaria Abstract: Summary Concentrations of arsenic (As), cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) were determined in water samples and five fish organs (gills, liver, kidney, spleen, and muscle) of common carp (Cyprinus carpio L.) and common rudd (Scardinius erythrophthalmus L.) from the Topolnitsa reservoir (Bulgaria) in three seasons (spring, summer, and autumn). This water ecosystem is located in a copper mining and metallurgical region. Water metal concentrations were significantly higher in the summer than in the spring (p&lt;0.05). Moreover, As, Cd, Cu, and Zn concentrations were higher than the national limits. Qualitative factors &quot;element&quot; and &quot;fish organ&quot; had a stronger influence on metal bioaccumulation than the factors &quot;season&quot; and &quot;fish species&quot;. In fish, the highest metal levels were detected in the liver, spleen, kidney and gills, and the lowest in the dorsal muscle. Tissue levels were higher in the summer, but in general they were similar between the two Cyprinid fish. Fish muscles had the lowest metal levels at all times, but As and Pb exceeded the national and international standards. Therefore, we would not recommend fish consumption from Topolnitsa, as continuous metal contamination of the reservoir may seem to present human health risk.",
Arsenic,1936192,"Modeling selenite adsorption envelopes on oxides, clay minerals, and soils using the triple layer model Abstract: Selenite adsorption behavior was investigated on amorphous Al and Fe oxides, clay minerals: kaolinite, montmorillonite, and illite, and 45 surface and subsurface soil samples from the southwestern and midwestern regions of the United States as a function of solution pH. Selenite adsorption decreased with increasing solution pH. The triple layer model, a chemical surface complexation model, was able to describe selenite adsorption as a function of solution pH by simultaneously optimizing both inner-sphere and outer-sphere selenite surface complexation constants. The fit of the triple layer model to selenite adsorption by soils was much improved over that obtained previously by optimizing solely an inner-sphere selenite surface complexation constant and the protonation constant in the constant capacitance model. In this previous application, the deprotonation constant had been neglected; thereby, preventing the reactive surface hydroxyl group from deprotonating; a chemically unrealistic situation. The selenite surface speciation predicted using the triple layer model was in agreement with that obtained for other strongly adsorbing anions such as molybdate. Direct spectroscopic investigations of selenite surface configuration are needed to corroborate the species predicted by the modeling approach.",
Arsenic,1240188,"Organoclays reduce arsenic bioavailability and bioaccessibility in contaminated soils Abstract: Purpose: Naturally occurring layer silicate clay minerals can be value added by modifying their surface properties to enhance their efficacy in the remediation of environmental contaminants. Silicate clay minerals modified by the introduction of organic molecules into the mineral structure are known as organoclays and show much promise for environmental remediation applications. The present study assesses the extent of decrease in bioavailable and bioaccessible arsenic (As) via enhanced adsorption by soil treated with organoclays. Materials and methods: Organoclays were prepared from hexadecyl trimethylammonium bromide (HDTMA) and Arquad registered 2HT-75 (Arquad) at surfactant loadings equivalent to twice the cation exchange capacity (CEC) of an Australian bentonite and characterised by X-ray diffraction (XRD). Batch experiments were conducted to evaluate the adsorption of arsenate onto the organoclays from aqueous solutions. Encouraged by these results, the organoclays were applied to As-spiked soils, at 10% and 20% (w/w) rates, to assess their capacity to stabilise soil As. After 1 month of incubation in the laboratory, bioavailable (1 mM Ca(NO sub(3)) sub(2) extractable) and bioaccessible (1 M glycine extractable) As from the spiked soils were assessed. Results and discussion: Both the organobentonites effectively removed As from aqueous solutions. The adsorbent prepared with Arquad adsorbed 23% more As from aqueous phase than adsorbent prepared with HDTMA. Adsorption of As was controlled by anion exchange and electrostatic attraction. When applied to As-contaminated soils, the organoclays reduced the bioavailable As by as much as 81%. The extent of reduction of bioaccessible As was only up to 58%. The adsorbents were not as efficient in reducing bioaccessible As in contaminated soils as compared with bioavailable As. It could be attributed to the extreme pH condition (pH=3) of the extractant used in the physiologically based extraction test method for assessing bioaccessibility. The greater the loading rate of organoclays, the better was the stabilisation of As in soils. Conclusions: Organobentonites prepared from HDTMA and Arquad at surfactant loadings greater than the CEC of the bentonite effectively remove As from aqueous solutions. Also, when applied to As-contaminated soils, both the organoclays reduce the bioavailability of soil As. The Arquad-modified bentonite performs better than HDTMA-modified bentonite. Data from this initial study can be used to further improve the stabilisation of soil As by using organoclays.",
Arsenic,1337825,"Inhibition of neurite outgrowth and alteration of cytoskeletal gene expression by sodium arsenite Abstract: Arsenic compounds that are often found in drinking water increase the risk of developmental brain disorders. In this study, we performed live imaging analyses of Neuro-2a cells expressing SCAT3, a caspase-3 cleavage peptide sequence linking two fluorescent proteins; enhanced cyan fluorescence protein (ECFP) and Venus, to determine whether sodium arsenite (NaAsO(2); 0, 1, 5, or 10?M) affects both neurite outgrowth and/or induces apoptosis with the same doses and in the same cell cultures. We observed that the area ratio of neurite to cell body in SCAT3-expressing cells was significantly reduced by 5 and 10?M NaAsO(2), but not by 1?M, although the emission ratio of ECFP to Venus, an endpoint of caspase-3 activity, was not changed. However, cytological assay using apoptotic and necrotic markers resulted in that apoptosis, but not necrosis, was significantly induced in Neuro-2a cells when NaAsO(2) exposure continued after the significant effects of NaAsO(2) on neurite outgrowth were found by live imaging. These results suggested that neurite outgrowth was suppressed by NaAsO(2) prior to NaAsO(2)-induced apoptosis. Next, we examined the effects of NaAsO(2) on cytoskeletal gene expression in Neuro-2a cells. NaAsO(2) increased the mRNA levels of the light and medium subunits of neurofilament and decreased the mRNA levels of tau and tubulin in a dose-dependent manner; no significant effect was found in the mRNA levels of the heavy subunit of neurofilament, microtubule-associated protein 2, or actin. The changes in cytoskeletal gene expression are likely responsible for the inhibitory effects of NaAsO(2) on neurite outgrowth.",
Arsenic,1034445,"Percent mortalities and LC50 values for selected microcrustaceans exposed to Treflan, Cutrine-plus, and MSMA herbicides Abstract: ",
Arsenic,2279270,"The molar volumes of ions in solution, part 7. Electrostriction and hydration numbers of aqueous polyatomic anions at 25 °c Abstract: The standard partial molar volumes of 16 polyatomic more-or-less globular anions in aqueous solutions at 25 °C were calculated as the sum of the intrinsic and (negative) electrostrictive volumes and compared with the experimental values. The intrinsic volumes used an empirical additive to the bare ionic radius to account for void spaces near the ions. The volume shrinkage due electrostriction was calculated according to the shell-by-shell electrostatic method. Agreement for many of the anions was achieved, but in some cases, notably the trivalent phosphate and arsenate ones, the calculated values failed to reproduce the experimental ones within reasonable uncertainties of the sizes of the anions.",
Arsenic,1070471,"Application of hybrid blood purification treatment for severe acute arsine poisoning Abstract: <strong>OBJECTIVE: </strong>Severe acute arsine poisoning (SAAP) complicated by multiple organ dysfunction syndrome is a critical clinical illness. The limited efficacy of conventional drug therapy prompted us to investigate the application of hybrid blood purification treatment (HBPT) to improve the prognosis in critically ill patients. The present manuscript describes a series of cases treated with HBPT.<br /><br /><strong>METHODS: </strong>Eleven SAAP subjects were enrolled. The study did not include a control group, because of ethical issues. On the basis of conventional therapy, HBPT (plasma exchange [PE] + continuous venovenous hemofiltration [CVVH]) was used to treat SAAP. PE was performed once a day for 5 days, and CVVH was performed after each session of PE for 7 days or more; HBPT treatment duration amounted to an average of 10 days (range 7-18 days). Arsenic was detected in blood and discarded liquid. Clinical indicators, laboratory parameters, and prognostic indicators were assessed.<br /><br /><strong>RESULTS: </strong>HBPT was smoothly implemented without obvious adverse reaction. It can continuously remove arsenic and terminate hemolysis in a time-dependent manner. HBPT also significantly improved the poor clinical manifestations and laboratory indicators of SAAP, leading to a low mortality. Ten patients were discharged because of improved conditions, and only 1 patient died.<br /><br /><strong>CONCLUSIONS: </strong>The early application of HBPT can improve the prognosis of SAAP. The advantage of HBPT is that it can integrate the characteristics of different blood purification technologies to maximize treatment efficacy.",
Arsenic,627965,"Neurosensory effects of chronic exposure to arsenic via drinking water in Inner Mongolia: II. Vibrotactile and visual function Abstract: This study was designed to assess the effects of exposure to arsenic in drinking water on visual and vibrotactile function in residents of the Bamen region of Inner Mongolia, China. Arsenic was measured by hydride generation atomic fluorescence. 321 participants were divided into three exposure groups- low (non-detectable-20), medium (100-300) and high (400-700 microg/l) arsenic in drinking water (AsW). Three visual tests were administered: acuity, contrast sensitivity and color discrimination (Lanthony's Desaturated 15 Hue Test). Vibration thresholds were measured with a vibrothesiometer. Vibration thresholds were significantly elevated in the high exposure group compared to other groups. Further analysis using a spline regression model suggested that the threshold for vibratory effects is between 150-170 microg/l AsW. These findings provide the first evidence that chronic exposure to arsenic in drinking water impairs vibrotactile thresholds. The results also indicate that arsenic affects neurological function well below the 1000 microg/I concentration reported by NRC (1999). No evidence of arsenic-related effects on visual function was found.",
Arsenic,1382087,BAL therapy in acute arsenical poisoning and gold intoxication Abstract: ,
Arsenic,2346013,Pre- plus postnatal exposures to di-(2-ethylhexyl)-phthalate and thyroid dysfunction in prematurely born children Abstract: ,
Arsenic,1797794,"Arsenic(III) and iron(II) co-oxidation by oxygen and hydrogen peroxide: Divergent reactions in the presence of organic ligands Abstract: Iron-catalyzed oxidation of As(III) to As(V) can be highly effective for toxic arsenic removal via Fenton reaction and Fe(II) oxygenation. However, the contribution of ubiquitous organic ligands is poorly understood, despite its significant role in redox chemistry of arsenic in natural and engineered systems. In this work, selected naturally occurring organic ligands and synthetic ligands in co-oxidation of Fe(II) and As(III) were examined as a function of pH, Fe(II), H2O2, and radical scavengers (methanol and 2-propanol) concentration. As(III) was not measurably oxidised in the presence of excess ethylenediaminetetraacetic acid (EDTA) (i.e. Fe(II):EDTA&lt;1:1), contrasting with the rapid oxidation of Fe(II) by O2 and H2O2 at neutral pH under the same conditions. However, partial oxidation of As(III) was observed at a 2:1 ratio of Fe(II):EDTA. Rapid Fe(II) oxidation in the presence of organic ligands did not necessarily result in the coupled As(III) oxidation. Organic ligands act as both iron speciation regulators and radicals scavengers. Further quenching experiments suggested both hydroxyl radicals and high-valent Fe species contributed to As(III) oxidation. The present findings are significant for the better understanding of aquatic redox chemistry of iron and arsenic in the environment and for optimization of iron-catalyzed arsenic remediation technology.",
Arsenic,1350427,"Glyoxalase I is a novel nitric-oxide-responsive protein Abstract: To clarify the molecular mechanisms of nitric oxide (NO) signalling, we examined the NO-responsive proteins in cultured human endothelial cells by two-dimensional (2D) PAGE. Levels of two proteins [NO-responsive proteins (NORPs)] with different pI values responded to NO donors. One NORP (pI 5.2) appeared in response to NO, whereas another (pI 5.0) disappeared. These proteins were identified as a native form and a modified form of human glyoxalase I (Glox I; EC 4. 4.1.5) by peptide mapping, microsequencing and correlation between the activity and the isoelectric shift. Glox I lost activity in response to NO, and all NO donors tested inhibited its activity in a dose-dependent manner. Activity and normal electrophoretic mobility were restored by dithiothreitol and by the removal of sources of NO from the culture medium. Glox I was selectively inactivated by NO; compounds that induce oxidative stress (H(2)O(2), paraquat and arsenite) failed to inhibit this enzyme. Our results suggest that NO oxidatively modifies Glox I and reversibly inhibits the enzyme's activity. The inactivation of Glox I by NO was more effective than that of glyceraldehyde-3-phosphate dehydrogenase (G3PDH), another NO-sensitive enzyme. Thus Glox I seems to be a novel NO-responsive protein that is more sensitive to NO than G3PDH.",
Arsenic,1597372,"Using FLOWFFF and HPSEC to determine trace metal-colloid associations in wetland runoff Abstract: Natural organic matter (NOM) and iron colloids can coexist in surface water. These colloids might exhibit different affinities to metals and metalloids. Previously it has been shown, that organic and inorganic colloids in the low nanometer range can be fractionated using Flow Field-Flow Fractionation analyzes (FlowFFF), but it is not yet understood how the presence of inorganic colloids influences results obtained by High Performance Size Exclusion Chromatography (HPSEC). Studies that compare the use of these size-separation techniques for the analyzes of organic and inorganic colloids and associated elements are needed in order to interpret results obtained by either of these methods. Therefore, associations between colloids from a small stream draining a wetland area and a selected range of elements (Fe, Al, Ti, Pb, Cu, Ni, As, U, and Rare Earth Elements (REE)) have been investigated. FlowFFF analyzes and HPSEC analyzes were combined with ultrafiltration, functional group titration and arsenic speciation analysis. NOM and, in a sample with a pH &gt; 5.2, slightly larger iron organo-mineral colloids, were present in the &lt;0.2 ?m fraction in the surface water. Both exhibited notably different affinities for trace elements. Cu, Ni, Al, and the REE all showed similar modes (i.e. peak maxima) and size distributions to the NOM, while Pb and As showed a preferential association with iron organo-mineral colloids. It was not possible to differentiate between NOM and iron-organo mineral colloids with HPSEC. The differences in the results regarding the apparent molecular mass distributions obtained by FlowFFF and HPSEC are discussed.",
Arsenic,2343491,"Autoubiquitination of the 26S proteasome on Rpn13 regulates breakdown of ubiquitin conjugates Abstract: Degradation rates of most proteins in eukaryotic cells are determined by their rates of ubiquitination. However, possible regulation of the proteasome's capacity to degrade ubiquitinated proteins has received little attention, although proteasome inhibitors are widely used in research and cancer treatment. We show here that mammalian 26S proteasomes have five associated ubiquitin ligases and that multiple proteasome subunits are ubiquitinated in cells, especially the ubiquitin receptor subunit, Rpn13. When proteolysis is even partially inhibited in cells or purified 26S proteasomes with various inhibitors, Rpn13 becomes extensively and selectively poly-ubiquitinated by the proteasome-associated ubiquitin ligase, Ube3c/Hul5. This modification also occurs in cells during heat-shock or arsenite treatment, when poly-ubiquitinated proteins accumulate. Rpn13 ubiquitination strongly decreases the proteasome's ability to bind and degrade ubiquitin-conjugated proteins, but not its activity against peptide substrates. This autoinhibitory mechanism presumably evolved to prevent binding of ubiquitin conjugates to defective or stalled proteasomes, but this modification may also be useful as a biomarker indicating the presence of proteotoxic stress and reduced proteasomal capacity in cells or patients.",
Arsenic,1024668,"In vitro cytogenetic effects of Andrographis paniculata (kalmegh) on arsenic Abstract: In vitro effects of arsenic in human peripheral lymphocytes (HPL) at three different doses - 3.6x10(-4), 1.4 x 10(-3) and 0.72 x 10(-3) microM for 24h before harvesting on sister chromatid exchanges (SCE), Cell cycle proliferative index/replicative index (CCPI/RI), %M(1), %M(2) and %M(3), population doubling time (PDT) and average generation time (AGT) were examined. Andrographis paniculata (commonly referred to as 'kalmegh') has been used for centuries in traditional Indian and Chinese herbal medicine as a safe, natural folk remedy for assorted health concerns. In the present study, kalmegh (0.01 microg/7ml culture media) was used along with the highest dose of arsenic; the results showed that arsenic induced increase in these genotoxic endpoints were fairly diminished by kalmegh. In addition, mutagenic in vitro effect of ethyl methanesulphonate (EMS) was used as a positive control in this study. It is thus concluded from this study that Andrographis has a protective role in arsenic toxicity.",
Arsenic,1340107,"Single blood-Hg samples can result in exposure misclassification: temporal monitoring within the Japanese community (United States) Abstract: <strong>BACKGROUND: </strong>The most prominent non-occupational source of exposure to methylmercury is the consumption of fish. In this study we examine a fish consuming population to determine the extent of temporal exposure and investigate the extent to which single time estimates of methylmercury exposure based on blood-Hg concentration can provide reliable estimates of longer-term average exposure.<br /><br /><strong>METHODS: </strong>Blood-mercury levels were obtained from a portion of the Arsenic Mercury Intake Biometric Study (AMIBS) cohort. Specifically, 56 Japanese women residing in the Puget Sound area of Washington State, US were sampled on three occasions across a one-year period.<br /><br /><strong>RESULTS: </strong>An average of 135 days separated samples, with mean blood-mercury levels for the visits being 5.1, 6.6 and 5.0 ?g/l and geometric means being 2.7, 4.5 and 3.1 ?g/l. The blood-mercury levels in this group exceed national averages with geometric means for two of the visits being between the 90th and 95th percentiles of nationally observed levels and the lowest geometric mean being between the 75th and 90th percentile. Group means were not significantly different across sampling periods suggesting that exposure of combined subjects remained relatively constant. Comparing intra-individual results over time did not reveal a strong correlation among visits (r?=?0.19, 0.50, 0.63 between 1st and 2nd, 2nd and 3rd, and 1st and 3rd sample results, respectively). In comparing blood-mercury levels across two sampling interval combinations (1st and 2nd, 2nd and 3rd, and 1st and 3rd visits, respectively), 58% (n?=?34), 53% (n?=?31) and 29% (n?=?17) of the individuals had at least a 100% difference in blood-Hg levels.<br /><br /><strong>CONCLUSIONS: </strong>Point estimates of blood-mercury, when compared with three sample averages, may not reflect temporal variability and individual exposures estimated on the basis of single blood samples should be treated with caution as indicators of long-term exposure. Reliance on single blood samples can make predicting ongoing methylmercury exposure highly speculative due to the large intra-individual variability.",
Arsenic,2298712,"Arsenic exposure, AS3MT polymorphism, and neuropsychological functioning among rural dwelling adults and elders: A cross-sectional study Abstract: BACKGROUND: The aim was to examine the link between low-level arsenic exposure and cognitive functioning, and the potential role of a single nucleotide polymorphism (SNP A35991G, rs10748835) of the AS3MT gene in modifying this link.<br /><br /><strong>METHODS: </strong>Data were analyzed on 526 participants from Project FRONTIER. Hierarchical linear regressions were created with neuropsychological raw index scores as the outcome variable and arsenic exposure and AS3MT SNP as different predictor variables.<br /><br /><strong>RESULTS: </strong>Within the total sample, arsenic exposure was negatively associated with language (p < 0.001) and executive functioning (p < 0.001). Among those with the AA genotype of the AS3MT gene, arsenic levels were negatively associated with language (p < 0.001), attention (p = 0.01), and executive functioning (p = 0.04). Among those with the AG genotype, arsenic levels were positively associated with immediate (p = 0.04) and delayed memory (p < 0.001) and negatively associated with executive functioning (p = 0.03). Among those with the GG genotype, arsenic levels were negatively associated with visuospatial functioning (p = 0.02).<br /><br /><strong>CONCLUSIONS: </strong>Low-level arsenic exposure is associated with cognitive functioning; however, this association is modified by an AS3MT gene.",
Arsenic,1337261,"Measurement of ?(18) O values in arsenic and selenium oxyanions Abstract: <strong>RATIONALE: </strong>Past stable isotopic studies of selenium and arsenic oxyanions within a biogeochemistry context have focused solely on selenium isotopes due to monoisotopic nature of arsenic and lack of attention to oxygen. A modern quantification method of ?(18) O values in selenate, selenite, arsenate, and arsenite is presented here, similar to methods for other inorganic oxyanions such as phosphate.<br /><br /><strong>METHODS: </strong>Dissolved oxyanions were recovered after precipitation with silver or barium cations within controlled pH ranges and purified by drying and roasting under vacuum. Oxygen isotope ratio measurements were performed on 250-450 micrograms of solids using continuous flow high-temperature conversion elemental analyzer/isotope ratio mass spectrometry (CF-TCEA/IRMS). Each Se and As solid was evaluated for reproducibility and stability of ?(18) O values and the usefulness of this method for evaluating aqueous phase Se and As oxyanion reactions was addressed.<br /><br /><strong>RESULTS: </strong>Only silver arsenate and barium selenate were shown to have stable, reproducible ?(18) O values over 5?months and were calibrated to the VSMOW scale. The method was applied to confirm complete exchange of oxygen isotopes between arsenate and solvent water at pH 7 which produced an O-isotope fractionation between arsenate and water of 6.0‰. Furthermore, the method revealed the ability of oxygen in selenate to kinetically fractionate during reduction to elemental selenium by a green rust compound which produced a fractionation (20.9‰) larger than reported ?(80/76) Se values for similar reactions.<br /><br /><strong>CONCLUSIONS: </strong>The experimental and analytical conditions for ?(18) O analysis of Se and As oxyanions were detailed. ?(18) O analyses of As and Se oxyanions may be useful in biogeochemical studies for tracing chemical reaction pathways, determining environmental sources of Se, or diagnosing specific reaction mechanisms for As and Se oxyanions. Copyright © 2012 John Wiley &amp; Sons, Ltd.",
Arsenic,1677583,"Increases in oxidized low density lipoprotein and other inflammatory and adhesion molecules with a concomitant decrease in high density lipoprotein in the individuals exposed to arsenic in Bangladesh Abstract: Elevated exposure to arsenic has been suggested to be associated with atherosclerosis leading to cardiovascular disease (CVD). However, biochemical events underlying the arsenic-induced atherosclerosis have not yet been fully documented. The aim of this study was to investigate the associations of circulating molecules involved in atherosclerosis with arsenic exposure in the individuals exposed to arsenic in Bangladesh. A total of 324 study subjects, 218 from arsenic-endemic areas and 106 from non-endemic area in Bangladesh were recruited. Drinking water, hair, nail and blood samples were collected from the study subjects for analysis. Total cholesterol (TC), low density lipoprotein (LDL) and high density lipoprotein (HDL) levels were lower in arsenic-endemic subjects than those of non-endemic subjects. Oxidized low density lipoprotein (Ox-LDL), C-reactive protein (CRP), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels were significantly higher in arsenic-endemic subjects than those of non-endemic subjects. All these circulating molecules showed significant correlations with arsenic exposure (water, hair and nail arsenic concentrations) and all these relations were significant before and after adjusting for relevant covariates. Among the circulating molecules tested in this study, HDL, Ox-LDL and CRP showed dose-response relationships with arsenic exposure. Ox-LDL/HDL ratios were increased with the increasing concentrations of arsenic in the water, hair and nails. Furthermore, non-HDL cholesterol and TC/HDL ratios were significantly correlated with arsenic exposure before and after adjusting for relevant covariates. Thus all the observed associations may be the major features of arsenic exposure related atherosclerosis leading to CVD.",
Arsenic,1018884,"Polycyclic aromatic hydrocarbon/metal mixtures: effect on PAH induction of CYP1A1 in human HEPG2 cells Abstract: Environmental polycyclic aromatic hydrocarbons (PAHs) and metals coexist, and such mixtures could affect the carcinogenicity of PAHs, possibly by modification of PAH induction of the PAH-bioactivating CYP1A. The effect on PAH-mediated CYP1A induction of arsenic, lead, mercury, or cadmium (ranked as the most hazardous environmental metals by the Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry) has thus been investigated. Induction of CYP1A1 by benzo[a]pyrene (BAP), benzo[b]fluoranthene (BBF), dibenzo[a,h]anthracene (DBAHA), benzo[a]anthracene (BAA), or benzo[k]fluoranthene (BKF) was probed by ethoxyresorufin-O-deethylase activity (EROD) in 96-well plates of human HepG2 cells, by immunoblot analysis, and by reverse transcription-polymerase chain reaction. Cells rapidly took up PAHs (BAP, BKF) from medium; by 24 h only 14% remained in the medium, and no detectable PAH bound to well walls. Induction efficiency (relative to dimethyl sulfoxide controls) was in the order BKF (16-fold) &gt; DBAHA (14-fold) &gt; BAA (4-fold) &gt; BAP (3-fold) &gt; BBF (1-fold), all at 5 microM PAH. The metals did not markedly affect cell viability at concentrations of arsenic, 5 microM; lead, 50 microM; mercury, 5 microM; and cadmium, 5 microM. At 5 microM PAH concentration, all of the metals decreased levels of PAH-induced CYP1A1 activities (direct inhibition of EROD activity was excluded) by variable extents and in a PAH-dependent manner. With BAP as inducer decreases in induction were arsenic, 57%; cadmium, 82%; mercury, 4%; and lead, 20%. The decreases were not a consequence of transcriptional down-regulation. One possible conclusion is that these metals could diminish PAH carcinogenic potential by decreasing PAH-mediated induction of their bioactivation by CYP1A1.",
Arsenic,628734,"DNA damage induced by methylated trivalent arsenicals is mediated by reactive oxygen species Abstract: Arsenic is a human carcinogen; however, the mechanisms of arsenic's induction of carcinogenic effects have not been identified clearly. We have shown previously that monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)) are genotoxic and can damage supercoiled phiX174 DNA and the DNA in peripheral human lymphocytes in culture. These trivalent arsenicals are biomethylated forms of inorganic arsenic and have been detected in the urine of subjects exposed to arsenite and arsenate. We show here by molecular, chemical, and physical methods that reactive oxygen species (ROS) are intermediates in the DNA-damaging activities of MMA(III) and DMA(III). Using the phiX174 DNA nicking assay we found that the ROS inhibitors Tiron, melatonin, and the vitamin E analogue Trolox inhibited the DNA-nicking activities of both MMA(III) and DMA(III) at low micromolar concentrations. The spin trap agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) also was effective at preventing the DNA nicking induced by MMA(III) and DMA(III). ESR spectroscopy studies using DMPO identified a radical as a ROS intermediate in the DNA incubations with DMA(III). This radical adduct was assigned to the DMPO-hydroxyl free radical adduct on the basis of comparison of the observed hyperfine splitting constants and line widths with those reported in the literature. The formation of the DMPO-hydroxyl free radical adduct was dependent on time and the presence of DMA(III) and was completely inhibited by Tiron and Trolox and partially inhibited by DMSO. Using electrospray mass spectrometry, micromolar concentrations of DMA(V) were detected in the DNA incubation mixtures with DMA(III). These data are consistent with the conclusions that the DNA-damaging activity of DMA(III) is an indirect genotoxic effect mediated by ROS-formed concomitantly with the oxidation of DMA(III) to DMA(V).",
Arsenic,1339331,"Arsenic exposure and tobacco consumption: Biomarkers and risk assessment Abstract: Arsenic is measurable in tobacco and cigarette mainstream smoke (MSS). Whether arsenic has an independent role in diseases associated with tobacco consumption is not known. Epidemiology and biomonitoring data and probabilistic risk assessment (PRA) methods were used to investigate this potential association. Analysis of data from the National Health and Nutrition Examination Survey (NHANES) showed that urine arsenic concentrations in tobacco consumers were not different or were lower than levels in non-consumers of tobacco. Additionally, urine arsenic levels from NHANES tobacco consumers were five-times or more lower than levels reported in epidemiology studies to be associated with adverse health effects. Results of PRA indicated that mean non-cancer hazard estimates and mean incremental lifetime cancer risk estimates were within accepted ranges. Taken together, these results suggest that arsenic may not be independently associated with tobacco consumption or diseases related to tobacco consumption.",
Arsenic,1070388,"NADPH oxidase-produced superoxide mediates EGFR transactivation by c-Src in arsenic trioxide-stimulated human keratinocytes Abstract: Arsenic is a well-known poison and carcinogen in humans. However, it also has been used to effectively treat some human cancers and non-carcinogenic ailments. Previously, we demonstrated in keratinocytes that arsenic trioxide (ATO)-induced p21( WAF1/CIP1 ) (p21) expression leading to cellular cytotoxicity through the c-Src/EGFR/ERK pathway and generation of reactive oxygen species (ROS). In this study, we found that EGFR-Y845 and EGFR-Y1173 could be phosphorylated by ATO. Using confocal microscopy and flow cytometry, we found that pretreatment with apocynin, DPI, and tiron could remove ATO-induced ROS production. Furthermore, to increase NADPH oxidase activity, ATO could induce cytosolic p67( phox ) expression and translocation to membrane. In addition, knockdown of p67( phox ) could abolish ATO-induced ROS production. Therefore, we suggest that NADPH oxidase-produced superoxide was a major source of ATO-induced ROS production. Conversely, ATO-induced NADPH oxidase activation and superoxide generation could be inhibited by the c-Src inhibitor PP1, but not by the EGFR inhibitor PD153035. In addition, overexpression of c-Src as well as treatment with ATO could stimulate EGFR-Y845/ERK phosphorylation, p21 expression, and cellular arrest/apoptosis, which could be attenuated by pretreatment with apocynin or knockdown of p67( phox ). Collectively, we suggest that NADPH oxidase was involved in the ATO-induced arrest/apoptosis of keratinocytes, which was regulated by c-Src activation.",
Arsenic,1328608,"Reversal of Bcl-2-mediated resistance of the EW36 human B-cell lymphoma cell line to arsenite- and pesticide-induced apoptosis by PK11195, a ligand of the mitochondrial benzodiazepine receptor Abstract: Opening of the permeability transition (PT) pore is a central feature of apoptosis induction by chemical stress. One component of the PT pore, the mitochondrial benzodiazepine receptor (mBzR), has recently received attention for its potential role in modulating PT pore function. Specifically, antagonistic ligands of the mBzR, such as 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline-carboxamide (PK11195), have been shown to sensitize Bcl-2 overexpressing cells to apoptosis induction by facilitating the opening of the PT pore and the subsequent loss of mitochondrial membrane potential (Deltapsim). We examined whether PK11195 can sensitize EW36, a human B-cell lymphoma cell line that over-expresses Bcl-2, to apoptosis induction and mitochondrial depolarization by environmental chemicals including mitochondrial toxicants. We found that, although EW36 cells are refractory to apoptosis induction by antimycin A, rotenone, pyridaben, alachlor, and carbonyl cyanide m-chlorophenylhydrazone (mClCCP), they are dramatically sensitized to induction of apoptosis by low concentrations of these same agents following pre-treatment with PK11195. The sensitization of EW36 cells is accompanied by a rapid and extensive loss of Deltapsim within a few hours following chemical exposure. Furthermore, using sodium arsenite, we examined the role of the c-Jun N-terminal kinase (JNK) pathway and protein synthesis in apoptosis induction in EW36. We found that, unlike untreated cells, EW36 cells treated with PK11195 no longer show an association of JNK pathway activation with apoptosis induction. Importantly, PK11195 eliminates a requirement for protein synthesis in chemically induced apoptosis in EW36 cells. These results show significant drug-mediated alteration of cell sensitivity and JNK pathway activation to environmental chemicals and mitochondrial toxicants, following ligation of the mBzR.",
Arsenic,2231462,"Inorganic arsenic in seafood: Does the extraction method matter? Abstract: Nine different extraction methods were evaluated for three seafood samples to test whether the concentration of inorganic arsenic (iAs) determined in seafood is dependent on the extraction method. Certified reference materials (CRM) DOLT-4 (Dogfish Liver) and TORT-2 (Lobster Hepatopancreas), and a commercial herring fish meal were evaluated. All experimental work described here was carried out by the same operator using the same instrumentation, thus eliminating possible differences in results caused by laboratory related factors. Low concentrations of iAs were found in CRM DOLT-4 (0.012±0.003mgkg(-1)) and the herring fish meal sample (0.007±0.002mgkg(-1)) for all extraction methods. When comparing the concentration of iAs in CRM TORT-2 found in this study and in the literature dilute acids, HNO3 and HCl, showed the highest extracted iAs wheras dilute NaOH (in 50% ethanol) showed significantly lower extracted iAs. However, most other extraction solvents were not statistically different from one another.",
Arsenic,2347658,"A Raman spectroscopic study of the arsenate mineral chenevixite Cu2Fe2(3+)(AsO4)2(OH)4?H2O Abstract: We have studied the mineral chenevixite from Manto Cuba Mine, San Pedro de Cachiyuyo District, Inca de Oro, Chañaral Province, Atacama Region, Chile, using a combination of scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX) and vibrational spectroscopy. Qualitative chemical analysis shows a homogeneous composition, with predominance of As, Fe, Al, Cu, Fe and Cu. Minor amounts of Si were also observed. Raman spectroscopy complimented with infrared spectroscopy has been used to assess the molecular structure of the arsenate minerals chenevixite. Characteristic Raman and infrared bands of the (AsO4)(3-) stretching and bending vibrations are identified and described. The observation of multiple bands in the (AsO4)(3-) bending region offers support for the loss of symmetry of the arsenate anion in the structure of chenevixite. Raman bands attributable to the OH stretching vibrations of water and hydroxyl units were analysed. Estimates of the hydrogen bond distances were made based upon the OH stretching wavenumbers.",
Arsenic,1017757,"Activity of phosphatases in the hemocytes of estuarine edible mudcrab, Scylla serrata exposed to arsenic Abstract: Sundarbans biosphere reserve is an ecologically important area of West Bengal, which supports a wide variety of estuarine species including Scylla serrata estuarine mudcrab of economic value. In this present study, activity of phosphatases (acid and alkaline) of hemocytes was estimated under the sublethal exposure of arsenic in controlled static water environment for 1, 2, 3, 4, 7 and 15 days of exposure. Exposure to 3 ppm of sodium arsenite for 15 days, resulted a maximum inhibition of activity of acid phosphatase (ACP) as 0.016 microM mg(-1) protein min(-1) with intermediate activity in different spans of exposure against the control value of 1.83 microM mg(-1) protein min(-1). Similar mode of maximum inhibition of activity of alkaline phosphatase (ALP) was recorded as 0.008 microM mg(-1) protein min(-1), when the crabs were exposed to 3 ppm of sodium arsenite for 15 days against the control value of 0.694 microM mg(-1) protein min(-1). Exposure to 1 ppm of sodium arsenite caused inhibition of activity of ACP which ranged from 1.76 to 0.70 microM mg(-1) protein min(-1). For 2 and 3 ppm of exposure activity of ACP ranged from 1.12 to 0.42 and 0.67 to 0.016 microM mg(-1) protein min(-1) respectively. For the activity of ALP exposure to 2 and 3 ppm of sodium arsenite yielded an inhibition of activity which ranged from 0.472 to 0.279 and 0.275 to 0.008 microM mg(-1) protein min(-1) respectively. Arsenic exposure resulted a dose dependent decrease in the activities of both of the phosphatases and may be considered as a suitable biomarker of aquatic pollution in Sundarbans mangrove.",
Arsenic,2337161,"Arsenolipids show different profiles in muscle tissues of four commercial fish species Abstract: Identification of arsenolipids in biological samples is today a challenge and in particular the need for speciation data for toxicological assessment. Fish is one of the major contributors of arsenic in diet. However, the majority of work in this area has only focused on the water soluble compounds. The aim of this study is to provide some data on total arsenic and in particular to gain insights into the types of arsenolipids in the muscle tissues of four commercial and commonly consumed fish species. Determination of total arsenic was carried out by ICP-MS following microwave-assisted acid digestion of the samples and the concentrations found for total arsenic in the muscles ranged from 4.8 to 6.0?g/gd.w. Sequential extraction was carried out using hexane and MeOH/DCM followed by reversed phase HPLC-ICP-MS/ESI-MS analysis of the MeOH/DCM fraction. Eight arsenolipids including three arsenic fatty acids (AsFAs) and five arsenic hydrocarbons (AsHCs) were identified. The result showed that fish with higher arsenolipid (AsLp) content (brill and sardine) are dominated by AsHC, while those with the smaller proportion of AsLp (mackerel and red mullet) have predominately arsenic in the form of AsFA.",
Arsenic,1016580,"Arsenite and its biomethylated metabolites interfere with the formation and repair of stable BPDE-induced DNA adducts in human cells and impair XPAzf and Fpg Abstract: The underlying mechanisms of arsenic carcinogenicity are only poorly understood and especially the role of biomethylation is still a matter of debate. Besides the induction of oxidative DNA damage the interference with DNA repair processes have been proposed to contribute to arsenic-induced carcinogenicity. Within the present study the effects of arsenite and its mono- and dimethylated trivalent and pentavalent metabolites on BPDE-induced DNA adduct formation and repair has been investigated and compared in cultured human lung cells. Whereas only arsenite and MMA(III) increased BPDE-DNA adduct formation, arsenite (&gt;/=5 microM), the trivalent (&gt;/=2.5 microM) and the pentavalent (&gt;/=250 microM) metabolites diminished their repair at non-cytotoxic concentrations. As potential molecular targets, interactions with the zinc finger domain of the human XPA protein (XPAzf) and the Escherichia coli zinc finger protein Fpg, involved in NER and BER, respectively, have been investigated. All trivalent arsenicals were able to release zinc from XPAzf; furthermore, MMA(III) and DMA(III) inhibited the activity of isolated Fpg. Altogether the results suggest that besides arsenite, especially the trivalent methylated metabolites may contribute to diminished NER at low concentrations.",
Arsenic,1345848,NATO Science for Peace and Security Series C-Environmental Security A Worldwide Emergency: Arsenic Risk in Water. Case Study of an Abandoned Mine in Italy Abstract: ,
Arsenic,2343451,"ArsH from Synechocystis sp. PCC 6803 reduces chromate and ferric iron Abstract: ArsH is widely distributed in bacteria and its function remains to be characterized. In this study, we investigated the function of ArsH from Synechocystis sp. PCC 6803. The inactivation of arsH by insertion of a kanamycin resistance gene in Synechocystis sp. PCC 6803 resulted in the decrease of arsenic and chromium accumulation compared with the wild type. ArsH expression in Escherichia coli strain Rosetta increased its resistance to chromate by reducing chromate in the medium and cells to chromium(III). In addition, ArsH in Rosetta conferred resistance to arsenic. The purified Synechocystis ArsH was able to reduce chromate and ferric iron at the expense of NADPH. Non-linear regression values of K0.5 for chromate and ferric iron were 26.6±3.7 ?M and 24.8±2.9 ?M respectively. The expression level of arsH was induced by arsenite and arsenate, but not chromate or ferric iron. Our results suggest that Synechocystis ArsH had no substrate specificities and shared some biochemical properties that other enzymes possessed. ArsH may be involved in coordinating oxidative stress response generated by arsenic. This article is protected by copyright. All rights reserved.",
Arsenic,1026187,"Reduction in urinary arsenic with bottled-water intervention Abstract: The study was conducted to measure the effectiveness of providing bottled water in reducing arsenic exposure. Urine, tap-water and toenail samples were collected from non-smoking adults residing in Ajo (n=40) and Tucson (n=33), Arizona, USA. The Ajo subjects were provided bottled water for 12 months prior to re-sampling. The mean total arsenic (microg/L) in tap-water was 20.3+/-3.7 in Ajo and 4.0+/-2.3 in Tucson. Baseline urinary total inorganic arsenic (microg/L) was significantly higher among the Ajo subjects (n=40, 29.1+/-20.4) than among the Tucson subjects (n=32, 11.0+/-12.0, p&lt;0.001), as was creatinine-adjusted urinary total inorganic arsenic (microg/g) (35.5+/-25.2 vs 13.2+/-9.3, p&lt;0.001). Baseline concentrations of arsenic (microg/g) in toenails were also higher among the Ajo subjects (0.51+/-0.72) than among the Tucson subjects (0.17+/-0.21) (p&lt;0.001). After the intervention, the mean urinary total inorganic arsenic in Ajo (n=36) dropped by 21%, from 29.4+/-21.1 to 23.2+/-23.2 (p=0.026). The creatinine-adjusted urinary total inorganic arsenic and toenail arsenic levels did not differ significantly with the intervention. Provision of arsenic-free bottled water resulted in a modest reduction in urinary total inorganic arsenic.",
Arsenic,1356231,"Risk of pancreatic cancer and occupational exposures in Spain Abstract: The objective of the study was to analyse the relationship between occupational exposures and risk of pancreatic cancer. Incident cases of pancreatic cancer and hospital controls were prospectively identified and interviewed during the hospital stay. Occupational history was obtained by direct interview with the patient, and was available for 164 (89%) of 185 pancreatic cancer cases, and 238 (90%) of 264 controls. Two industrial hygienists evaluated exposures to 22 suspected carcinogens previously associated with pancreatic cancer. Occupational exposures were also assessed using the Finnish job-exposure matrix (FINJEM). For each type of pesticide group, moderately increased odds ratios (OR) were apparent in the high-intensity category, highest for arsenical pesticides …OR ˆ 3:4; 95% CI 0.9±12.0), and `other pesticides' …OR ˆ 3:17; 95% CI 1.1±9.2). ORs for aniline derivatives, and dyes and organic pigments, were also higher for high-intensity exposure, and increased when lagged and restricted to long duration of exposure. ORs above 3 were observed for the following agents evaluated by FINJEM: pesticides, benzo[a ]pyrene, lead, volatile sulphur compounds, and sedentary work. Whilst generally negative, results lend moderate support to the hypothesis of an association between exposure to some pesticides and pancreatic cancer. Larger studies could address the potential for these compounds to modify the carcinogenic risk of other environmental exposures. Suggestive increases in risk from aniline derivatives, dyes and organic pigments, and benzo[a ]pyrene may also deserve further attention.",
Arsenic,627340,"Arsenic in drinking water and skin lesions: Dose-response data from West Bengal, India Abstract: BACKGROUND: Over 6 million people live in areas of West Bengal, India, where groundwater sources are contaminated with naturally occurring arsenic. The key objective of this nested case-control study was to characterize the dose-response relation between low arsenic concentrations in drinking water and arsenic-induced skin keratoses and hyperpigmentation. METHODS: We selected cases (persons with arsenic-induced skin lesions) and age- and sex-matched controls from participants in a 1995-1996 cross-sectional survey in West Bengal. We used a detailed assessment of arsenic exposure that covered at least 20 years. Participants were reexamined between 1998 and 2000. Consensus agreement by four physicians reviewing the skin lesion photographs confirmed the diagnosis in 87% of cases clinically diagnosed in the field. RESULTS: The average peak arsenic concentration in drinking water was 325 microg/liter for cases and 180 microg/liter for controls. The average latency for skin lesions was 23 years from first exposure. We found strong dose-response gradients with both peak and average arsenic water concentrations. CONCLUSIONS: The lowest peak arsenic ingested by a confirmed case was 115 microg/liter. Confirmation of case diagnosis and intensive longitudinal exposure assessment provide the basis for a detailed dose-response evaluation of arsenic-caused skin lesions.",
Arsenic,1070334,"Concentrations of Metals in Soils in the Neighborhood of a Hazardous Waste Incinerator: Assessment of the Temporal Trends Abstract: The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), tin (Sn), thallium (Tl), and vanadium (V) were determined in 30 soil samples collected in April 2011 near a hazardous waste incinerator (HWI; Constantí, Catalonia, Spain), which is under regular operations since 1999. The results were compared with those of recent surveys performed in the same zone, as well as with data from a background study (1996-1998). We also assessed the human health risks derived from metal exposure in the area under potential influence of the emissions of the HWI. Manganese was the most abundant element in soils, with a mean value of 316.4 ?g/g, followed by Pb and Cu (mean values, 42.5 and 38.2 ?g/g, respectively). In contrast, Sb, Cd, and Tl presented the lowest values (0.12, 0.27, and 0.29 ?g/g, respectively), while Hg was below its limit of detection. In the period 1998-2011, only As, Cr, Sn, Tl, and V levels presented significant increases in soils. The estimated carcinogenic and noncarcinogenic risks derived from exposure to these metals from soils should not mean any special concern for the population living in the surroundings of the HWI.",
Arsenic,2278925,"PP2A-AMPK?-HSF1 axis regulates the metal-inducible expression of HSPs and ROS clearance Abstract: Metals such as cadmium and arsenic are ubiquitous toxicants that cause a variety of adverse health effects. Heat shock proteins (HSPs) response to metal-induced stress and protect cells from further damage. However, the intracellular signalling pathways responsible for activation of HSPs expression are not fully understood. Here, we demonstrate that protein phosphatase 2A (PP2A) regulates expression of HSP70 and HSP27 via dephosphorylation of an AMP-activated protein kinase ? subunit (AMPK?) at Thr172. Dephosphorylated AMPK? phosphorylates heat shock factor 1 (HSF1) at Ser303, leading to significant transcriptional suppression of HSP70 and HSP27 in CdCl2- or NaAsO2-treated cells. Suppression of PP2A regulatory B56? subunit resulted in the sustained phosphorylation of AMPK? upon CdCl2 treatment, subsequent reduction in expression of HSP70 and HSP27, and thereby dramatic reduction of reactive oxygen species (ROS) clearance. We further revealed that PP2A B56? physically interacted with AMPK?, providing evidence that PP2A B56?-AMPK?-HSF1 signalling pathway participated in regulating the inducible expression of HSPs and ROS clearance. Taken together, we identified a novel PP2A-dependent signalling pathway involved in regulation of HSPs expression in response to metal stress.",
Arsenic,2064217,"Stabilization of Tetrahedral P4 and As4 Molecules as Guests in Polymeric and Spherical Environments Abstract: As you like it: [Ag(?(2) -As4 )2 ](+) [pftb](-) can be used to store yellow arsenic (As4 ). From it, As4 can be easily released to give concentrated, light-stable solutions. These As4 solutions, and those of white phosphorus (P4 ), allowed molecular As4 and P4 to be encapsulated inside giant, spherical aggregates and polymeric matrices, enabling the first determination of their E?E (E=P, As) bond lengths by diffraction methods.",
Arsenic,1032250,"Reversal of gallium arsenide-induced suppression of the antibody-forming cell response by vehicle supernatants. II. Nature and identification of reversing factors Abstract: Previous studies have demonstrated that several immunological events which are T cell mediated are significantly suppressed by a single exposure to gallium arsenide (GaAs). In addition, in the in vitro-generated antibody-forming cell (AFC) response supernatants from vehicle (VH) cultures were able to time-dependently reverse suppression induced by either in vivo (200 mg/kg) or in vitro (50 ?M) exposure to GaAs. The present studies were designed to determine the nature and identification of the reversing factors present in VH supernatants. VH supernatants (25-100%) were able to dose-dependently reverse suppression of the AFC response (from 45% suppression to 48% enhancement of the VH response) induced by GaAs exposure (200 mg/kg). Concentration of 24-hr VH supernatants and treatment with proteinases revealed that the reversing factors were protein in nature with a molecular weight between 5,000 and 50,000 Da. This molecular weight range encompasses many of the lymphokines known to be necessary for the generation of an immune response. In antibody cultures exposed either in vivo or in vitro to VH or GaAs, HT-2 bioassay and antigen capture enzyme-linked immunosorbent assays demonstrated that GaAs exposure alters production of interleukin (IL)-2, IL-4, IL-5 and IL-6. Interestingly, the alterations in lymphokine production differed between the exposure regimes. Direct addition of IL-2 to antibody cultures resulted in a dose-dependent (6.25-50 ng/ml) reversal of GaAs-induced suppression (in vivo exposure) and was also dependent on the concentration of GaAs (50-200 mg/kg). IL-4 suppressed the VH AFC response and failed to reverse GaAs suppression.",
Arsenic,1017585,"Effects of long-term exposure to iodine excess on the apoptosis of thyrocytes in Wistar rats Abstract: OBJECTIVE: To explore the effects of long-term exposure to more than adequate and excessive iodine on the apoptosis of thyrocytes in Wistar rats. METHODS: Wistar rats, divided into four groups: Group 0 (control, treated with 4 ?g/day of iodine), Group 1 (1.5x control dose, i.e. 6 ?g/day of iodine), Group 2 (3x control dose, i.e. 12 ?g/day of iodine), and Group 3 (6x control dose, i.e. 24 ?g/day of iodine) had oral iodine intake for 1, 2, 4, and 8 months before being sacrificed for study. After the initial treatment course of 8 months, some rats in each group continued to have an iodine intake at 4 ?g/day for extra 3 months. Urinary iodine concentration was measured by arsenic/cerium catalyzing spectrophotography. In addition, the early apoptosis was assessed by flow cytometry with Annexin V-FITC staining, while the late apoptosis was evaluated by TUNEL microscopy. Furthermore, the rate of cell death and cell cycle kinetics were determined by flow cytometry with propidium iodide (PI) staining. Moreover, the level of intracellular reactive oxygen species (ROS) quantified by the fluorescence intensity was measured via flow cytometry with a DCFH-DA probe. Immunohistochemistry technique was also used for the detection of the expression of Bcl-2 and Bax. RESULTS: The apoptotic rate and ROS production in thyrocytes were significantly elevated in Groups 2 and 3 after 4 and 8 months of treatment compared to the control group ( P<0.05). Groups 2 and 3 were also found to have greatly higher percentage of cells in S phase after 4 and 8 months of exposure (5%-6% vs. 3%, P<0.05), with a significant reduction in cells in G0G1-phase (64%-67% vs. 80%, P<0.05). These differences disappeared after normal iodine intake for extra 3 months. The expressions of Bcl-2 and Bax among different groups remained unchanged. Positive correlations were observed between the apoptotic rate, ROS level and urinary iodine concentration after 4 and 8 months of excessive iodine exposure (r is in the range of 0.736~0.855, all of Ps<0.01). CONCLUSION: The experimental data indicated that more apoptosis of thyrocytes after exposure to excessive iodine was attributed to the increased free radical production, other than regulated Bcl-2 and Bax expression. The effects of iodine excess are reversible.",
Arsenic,626998,"More than tenfold increase of arsenic in serum and packed cells of chronic hemodialysis patients Abstract: Arsenic concentrations were determined in serum and packed cells of 7 chronic hemodialysis patients, in fresh dialysate and in a heparin solution. The analytical technique was radiochemical neutron activation analysis. The accuracy of the method was tested by the analysis of As in certified reference materials. Patients showed elevated serum and packed cell arsenic concentrations compared with controls (serum, range: 2.3-79.8 ng As/ml, median: 11.5 ng As/ml; versus range: 0.132-4.783 ng As/ml, median: 0.38 ng As/ml; packed cells, range: 2.1-68.4 ng As/g, median: 9.5 ng As/g; versus range: 0.51-14.44 ng As/g, median: 3.17 ng As/g). Arsenic concentrations remained unaltered, before versus after a single hemodialysis treatment. The arsenic contents of serum and packed cells were significantly correlated (n = 7, r = 0.96, p < 0.05). No arsenic could be detected in the heparin solution or in the dialysate.",
Arsenic,628660,"Arsenic trioxide–loaded, microemulsion-enhanced cytotoxicity on MDAH 2774 ovarian carcinoma cell line Abstract: The antiproliferative effect of As2O3-loaded microemulsion (As2O3-M) on human MDAH 2774 ovarian cancer cells was compared with a regular solution of the As2O3. We used MDAH 2774 as model cell lines for ovarian cancer. The (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide) (XTT) and trypane blue dye exclusion tests were used to evaluate cytotoxicity. Apoptotic effect of solutions was evaluated using cell death detection kit. Standard microemulsion formulation used in this experiment contains 5 × 10?6 M As2O3. It was clearly demonstrated that As2O3-M had a significant cytotoxic effect on MDAH 2774 cell line, and the cytotoxic effect of As2O3-M was significantly higher than that of regular As2O3 solutions. Even approximately 6000 times diluted microemulsion formulation loaded with 5 × 10?6 M As2O3 showed a cytotoxic effect. As a result, this diluted concentration (approximately 8 × 10?10 M) was found to be approximately 6000 times more effective than regular As2O3 solutions (5 × 10?6 M). Moreover, this diluted concentration resulted in 1.5-fold enhancement of apoptosis. According to the in vitro cytotoxicity studies, we concluded that by incorporating As2O3 into the microemulsion (As2O3-M), which is a new drug carrier system, it is possible to increase antiproliferative effect of regular As2O3 on MDAH 2774 cells. Translating these results to in vivo conditions would open new windows in the treatment of ovarian cancer.",
Arsenic,733262,"Immunotoxicological investigations on rats treated subacutely with dimethoate, As3+ and Hg2+ in combination Abstract: Effects of combined exposure with dimethoate (DM), HgCl2 (Hg), and NaAsO2 (As) were investigated following a 28 - day oral exposure in male Wistar rats. In preliminary experiments, the LOEL (Lowest Observed Effect Level) and NOEL (Non Observed Effect Level) doses of the substances were determined using the same experimental system [determination of body weight gain, organ weights of brain, thymus, heart, lung, kidneys, adrenals, spleen, testicles, popliteal lymph node, white blood cell (WBC) and red blood cell (RBC) count, haematocrit (Ht), mean cell volume (MCV) of RBCs, cell content of the femoral bone marrow, IgM-plaque forming cell (PFC) content of the spleen, delayed type hypersensitivity (DTH) reaction] and animal strain. In the combination studies, LOEL dose of DM (28.2 mg/kg) was combined with NOEL doses of the heavy metals ( HgCl2 = 0.40 mg/kg, NaAsO2 = 3.33 mg/kg), and vice versa (DM = 7.04 mg/kg, HgCl2 = 3.20 mg/kg, NaAsO2 = 13.3 mg/kg). In the DM-Hg combinations, significant alterations were found versus the corresponding high- dose internal control in the body weight gain, relative liver and kidney weights, and in the PFC response. When DM was combined with As, interactions were indicated by changes of relative liver weight, MCV value, and the PFC content of the spleen. These results support the theory that the interactions between pesticides and heavy metals may modify the toxic effects of the single substances, and may also change the functional detection limits of the exposure. The changes in the functional detection limits, if they occur, can lead to false-positive and false-negative results in human epidemiological studies.",
Arsenic,628398,"Studies on Blackfoot disease and chronic arsenism in southern Taiwan: With special reference to skin lesions and fluorescent substances Abstract: An endemic peripheral vascular disorder called ""blackfoot disease"" has been noticed in a limited area on the southern coast of Taiwan. Clinically, the symptoms and signs of blackfoot disease (BFD) are similar to those of Buerger's disease. The main ultrastructural change in the dermal blood vessel is degeneration of the endothelial cells. Among the inhabitants of this endemic area, a remarkable percentage of chronic arsenism is also found. It is currently believed that drinking of artesian well water containing both a fluorescent substance (FC) and arsenic is the cause of these two diseases. The purpose of this study is to examine the vascular and mutagenic effects of FC and also to discuss the roles of FC and arsenic in BFD and chronic arsenism. It was found that FC has the following effects: (1) inhibition of histamine-induced capillary permeability (2) degeneration in the capillary endothelial cells in vivo (3) mutagenesis, and (4) enhancement of the incorporation of sH-thymidine in low fetal calf serum containing cultured fibroblasts. This is strong evidence that",
Arsenic,1020518,"The paradox of arsenic: Molecular mechanisms of cell transformation and chemotherapeutic effects Abstract: Arsenic is a well-documented carcinogen that also appears to be a valuable therapeutic tool in cancer treatment. This creates a paradox for which no unified hypothesis has been reached regarding the molecular mechanisms that determine whether arsenic will act as a carcinogen or as an effectual chemotherapeutic agent. Much of our knowledge with respect to the actions of arsenic has been drawn from epidemiological or clinical studies. The actions of arsenic are likely to be related to cell type, arsenic species, and length and dose of exposure. Arsenic unquestionably induces apoptosis and may specifically target certain tumor cells. Research data strongly suggest that arsenic influences distinct signaling pathways involved in mediating proliferation or apoptosis, including mitogen-activated protein kinases, p53, activator protein-1 or nuclear factor kappa B. The primary purpose of this review is to examine recent findings, from this laboratory and others, that focus on the molecular mechanisms of arsenic's actions in cell transformation and as a therapeutic agent.",
Arsenic,710855,"Arsenite induced poly(ADP-ribosyl)ation of tumor suppressor P53 in human skin keratinocytes as a possible mechanism for carcinogenesis associated with arsenic exposure Abstract: Arsenite is an environmental pollutant. Exposure to inorganic arsenic in drinking water is associated with elevated cancer risk, especially in skin. Arsenite alone does not cause skin cancer in animals, but arsenite can enhance the carcinogenicity of solar UV. Arsenite is not a significant mutagen at non-toxic concentrations, but it enhances the mutagenicity of other carcinogens. The tumor suppressor protein P53 and nuclear enzyme PARP-1 are both key players in DNA damage response. This laboratory demonstrated earlier that in cells treated with arsenite, the P53-dependent increase in p21(WAF1/CIP1) expression, normally a block to cell cycle progression after DNA damage, is deficient. Here we show that although long-term exposure of human keratinocytes (HaCaT) to a nontoxic concentration (0.1 microM) of arsenite decreases the level of global protein poly(ADP-ribosyl)ation, it increases poly(ADP-ribosyl)ation of P53 protein and PARP-1 protein abundance. We also demonstrate that exposure to 0.1 microM arsenite depresses the constitutive expression of p21 mRNA and P21 protein in HaCaT cells. Poly(ADP-ribosyl)ation of P53 is reported to block its activation, DNA binding and its functioning as a transcription factor. Our results suggest that arsenite's interference with activation of P53 via poly(ADP-ribosyl)ation may play a role in the comutagenic and cocarcinogenic effects of arsenite.",
Arsenic,1032532,"Effect of sodium arsenite on the induction and turnover of ornithine decarboxylase activity in erythroleukemia cells Abstract: Sodium arsenite proved effective in preventing the induction of ornithine decarboxylase (ODC) activity elicited by dilution of Friend erythroleukemia cells in fresh medium. A 50 per cent inhibition was produced at approximately 1 microM arsenite and complete inhibition was obtained at concentrations above 10 microM. However, addition of arsenite 5 h after cell dilution, i.e. when ODC was already induced, appeared to stabilize the enzyme. The half-life of ODC activity, measured after cycloheximide treatment, increased almost six-fold after addition of sodium arsenite. Agents known to provoke oxidative alteration of the thiol-redox status in cells, also caused a similar effect on the induction and stability of ODC.",
Arsenic,1034588,"Health aspects of burning coal with a high arsenic content. I. Arsenic in hair, urine, and blood in children residing in a polluted area Abstract: Arsenic determination was carried out on hair, urine and blood samples taken from groups of 10-year old boys, each numbering 20-25 individuals, residing in a region polluted by arsenic. The source of arsenic emissions (1/2 to 1 ton perday) is a power plant burning local coal of high arsenic content. In all the materials examined, considerably elevated concentrations of arsenic were found. The relation of the observed levels of arsenic to the distance of the place of residence up to a distance of more than 30 km from the source of the emissions was studied. On the basis of the results obtained, the most advantageous material for estimation of nonoccupational exposure to this toxic agent seems to be hair, in spite of some problems with the decontamination procedure involved. The results coresponded to the theoretical ideas on spreading of emissions from elevated sources in the open air and tend to establish the applicability of arsenic determination in the hair as a direct exposure test of contamination of the environment by arsenic. Considerable variability among individual arsenic values in the hair makes group examination a necessity. The same applied to the urine and blood sampling, which is complicated by several technical difficulties. Levels in urine reflect the quantities of arsenic inhaled or ingested after their absorption into the blood, and give a more realistic picture of possible daily intake.",
Arsenic,2149166,"Laterally resolved speciation of arsenic in roots of wheat and rice using fluorescence-XANES imaging Abstract: Accumulation of arsenic (As) within plant tissues represents a human health risk, but there remains much to learn regarding the speciation of As within plants. We developed synchrotron-based fluorescence-X-ray absorption near-edge spectroscopy (fluorescence-XANES) imaging in hydrated and fresh plant tissues to provide laterally resolved data on the in situ speciation of As in roots of wheat (Triticum aestivum) and rice (Oryza sativa) exposed to 2 ?M As(V) or As(III). When exposed to As(V), the As was rapidly reduced to As(III) within the root, with As(V) calculated to be present only in the rhizodermis. However, no uncomplexed As(III) was detected in any root tissues, because of the efficient formation of the As(III)-thiol complex - this As species was calculated to account for all of the As in the cortex and stele. The observation that uncomplexed As(III) was below the detection limit in all root tissues explains why the transport of As to the shoots is low, given that uncomplexed As(III) is the major As species transported within the xylem and phloem. Using fluorescence-XANES imaging, we have provided in situ data showing the accumulation and transformation of As within hydrated and fresh root tissues.",
Arsenic,1015657,"Association of metals and proteasome activity in erythrocytes of prostate cancer patients and controls Abstract: Information is lacking on the effects toxic environmental metals may have on the 26S proteasome. The proteasome is a primary vehicle for selective degradation of damaged proteins in a cell and due to its role in cell proliferation, inhibition of the proteasome has become a target for cancer therapy. Metals are essential to the proteasome's normal function and have been used within proteasome-inhibiting complexes for cancer therapy. This study evaluated the association of erythrocyte metal levels and proteasome chymotrypsin-like (CT-like) activity in age- and race-matched prostate cancer cases (n?=?61) and controls (n?=?61). Erythrocyte metals were measured by inductively coupled plasma mass spectrometry (ICP-MS). CT-like activity was measured by proteasome activity assay using a fluorogenic peptide substrate. Among cases, significant correlations between individual toxic metals were observed (r(arsenic-cadmium)?=?0.49, p?&lt;?0.001; r(arsenic-lead)?=?0.26, p?=?0.04, r(cadmium-lead) 0.53, p?&lt;?0.001), but there were no significant associations between metals and CT-like activity. In contrast, within controls there were no significant associations between metals, however, copper and lead levels were significantly associated with CT-like activity. The associations between copper and lead and proteasome activity (r(copper-CT-like)?=?-0.28, p?=?0.002 ; r(lead-CT-like)?=?0.23, p?=?0.011) remained significant in multivariable models that included all of the metals. These findings suggest that biologically essential metals and toxic metals may affect proteasome activity in healthy controls and, further, show that prostate cancer cases and controls differ in associations between metals and proteasome activity in erythrocytes. More research on toxic metals and the proteasome in prostate cancer is warranted.",
Arsenic,1022259,"Effects of arsenite on glutamate metabolism in primary cultured astrocytes Abstract: The aim of this study was to explore the mechanisms that contribute to neurotoxicity induced by arsenite exposure focusing on the alteration of glutamate metabolism in primary cultured astrocytes. The cells were exposed to 0-30?M arsenite for 24h, and then cell viability, intracellular nonprotein sulfhydryl (NPSH) levels, mitochondrial membrane potential, activity of Na(+)/K(+)-ATPase, glutamine synthetase (GS) and glutamate transporter (GLAST and GLT-1), and protein expression of GS, GLAST and GLT-1 were examined. Compared with those in control, exposure to arsenite resulted in damages of astrocytes in a concentration dependent manner, which were shown by cell viabilities, and supported by morphological observation, mitochondrial membrane potential and intracellular NPSH levels. On the other hand, activities and protein expression of GS, GLAST and GLT-1 were significantly inhibited by arsenite exposure. Moreover, protein expression of GLAST and activities of GS were much more sensitive to arsenite. However, activities of Na(+)/K(+)-ATPase were not influenced obviously by arsenite exposure. In conclusion, findings from this study indicated that exposure to arsenite could inhibit glutamate metabolism in astrocytes, which might be related to arsenic-induced neurotoxicity.",
Arsenic,62172,"Effects of arsenic cell metabolism and cell proliferation: cytogenetic and biochemical studies Abstract: Chromosome analysis of lymphocytes from patients who had been exposed to arsenic showed frequent structural and numerical aberrations, even with an interval of decades since the last exposure. The in vitro addition of sodium arsenate induced the same chromosome changes--even to extreme of chromosome pulverizations--upon lymphocyte cultures from healthy subjects. Radioactive incorporation studies showed that arsenate was able to inhibit dose-dependently the incorporation of radioactively labeled nucleotide in RNA and DNA. Beyond that, arsenic blocked the cells in the S- and G2-phase. A general explanation for the inhibitory effect of inorganic arsenic on cell metabolism is the known strong affinity of arsenic to enzymes, especially to those containing sulfhydryl groups.",
Arsenic,1343953,"Effect of defatted methanolic extract of Holarrhena floribunda leaves in sodium arsenite-induced clastogenecity in Wistar albino rats Abstract: This study examined the effect of defatted methanolic extract of Holarrhena floribunda leaves on sodium arsenite-induced clastogenecity and toxicity in male wistar rats. Animals were randomly allotted into six groups of five rats each and treated as follows; Group A (sodium arsenite (NaAsO3)), Group B (100 mg/kg extract), Group C (100 mg/kg extract plus NaAsO3), Group D (200 mg/kg extract), Group E (200 mg/kg extract plus NaAsO3) and Group F had distilled water. Sodium arsenite (2.5 mg/kg) was given intraperitoneally once per week. The extract was administered through oral gavage for 28 consecutive days. Clastogenecity was evaluated by studying micronuclei formation in polychromatic erythrocytes cells (PCEs) in the bone marrow. Plasma levels of Gamma Glutamyl Transferase (ãGT), Aspartate Amino Transferase (AST), Alanine Amino Transferase (ALT) were determined. Hepatic Reduced Glutathione (GSH), Superoxide Dismutase (SOD), Catalase (CAT), protein and lipid peroxidation were determined. Liver histopathological evaluation was also carried out.The results obtained show that NaAsO3-induced micronuclei formation in PCEs was reduced at 100 and 200 mg/kg of the extract by 7.7% and 38.5% respectively while elevated plasma ãGT and ALT levels were significantly ameliorated (P<0.001). There was no significant difference in plasma AST levels and hepatic SOD activities in all the treated groups as compared with the control. Sodium arsenite-induced reduction of GSH concentration was elevated by the extract at 100 and 200 mg/kg by 18.5% and 11.9% respectively. The reduction of CAT activity by NaAsO3 was also ameliorated at 200 mg/kg extract by 23.3%. The extract at 100 mg/kg significantly reduced NaAsO3-induced lipid peroxidation by 16.4% (P < 0.05). Histological examinations showed that the extract at 100 mg/kg protected NaAsO3-induced liver damage. This study revealed that the leaf extract has potential to ameliorate clastogenecity and toxicity induced by sodium arsenite in rats.",
Arsenic,1018425,"Lipid profile and peripheral vascular disease in arseniasis-hyperendemic villages in Taiwan Abstract: To examine whether lipid abnormalities contributed to the endemic peripheral vascular disease (PVD) in villages where arseniasis was hyperendemic in Taiwan, the authors studied 533 adults with Doppler ultrasound and lipid profiles including total cholesterol, triglyceride, high- and low-density lipoprotein cholesterol, apolipoprotein AI, and apolipoprotein B. Among them, 63 had PVD based on an ankle-brachial index &lt; 0.90. Long-term arsenic exposure indices including cumulative arsenic exposure in mg/L-years, duration of drinking artesian well water in years, and duration of living in arseniasis-hyperendemic villages in years were calculated from detailed history obtained through standardized interviews based on a structured questionnaire and arsenic concentration in well water. Possible confounders including age, sex, body mass index, cigarette smoking, and disease status of diabetes mellitus and hypertension were considered in the analyses. None of the lipid profiles differed significantly between the presence and absence of PVD. The odds ratios for PVD did not differ among different quintiles of lipid profiles with the lowest quintile as the referent. However, a significant dose-response relation was found for the long-term arsenic exposure indices. The multivariate-adjusted odds ratios for cumulative arsenic exposure of 0.1 approximately 19.9 and &gt; or = 20 mg/L-years were 2.77 and 4.68, respectively, compared with the unexposed. These results suggest that the PVD in arseniasis-hyperendemic villages is correlated with ingested inorganic arsenic and not with the lipid profiles.",
Arsenic,1070420,"Arsenic interception by cell wall of bacteria observed with surface-enhanced Raman scattering Abstract: The purpose of this study was to determine the interactions between arsenic (As) resistant bacteria and As, using surface-enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopy. According to our 16S rDNA results, eight bacteria isolated from the environment can be identified to four genera (Arthrobacter, Pseudomonas, Sphingomonas, and Acinetobacter). The bacteria were separated into cell wall and protoplast in the study to assess the As(V) attack. The As(V) stress on bacteria could be identified with SERS, but not with FTIR. The bacteria in our study primarily resist As(V) through sequestration of As(V) by the cell wall. The change in SERS peaks and their relationships with cell wall suggested that As(V) mainly interacts with functional groups on the cell wall including polysaccharides and flavin derivates.",
Arsenic,1508656,"Physiological impacts of soil pollution and arsenic uptake in three plant species: Agrostis capillaris, Solanum nigrum and Vicia faba Abstract: In order to revegetate an industrial soil polluted by trace metals and metalloids (As, Pb, Cu, Cd, Sb), the impact of pollution on three plant species, Solanum nigrum and Agrostis capillaris, both native species in an industrial site, and Vicia faba, a plant model species, is studied. Following the study of soil pollution from the industrial wasteland of Auzon, it appears that the As is the principal pollutant. Particular attention is given to this metalloid, both in its content and its speciation in the soil that the level of its accumulation in plants. In V. faba and A. capillaris, the trace metals and metalloids inhibit the biomass production and involve a lipid peroxidation in the leaves. Furthermore, these pollutants cause a photosynthesis perturbation by stomatal limitations and a dysfunction of photosystem II. Whatever the plant, the As content is less than 0.1 percent of dry matter, the majority of As absorbed is stored in the roots which play the role of trap organ. In parallel, the culture of S. nigrum decreases significantly the exchangeable and weakly adsorbed fraction of As in rhizospheric soil. This study has highlighted the ability of tolerance to trace metals of S. nigrum and to a lesser extent A. capillaris. Our data indicate that V. faba is not tolerant to soil pollution and is not a metallophyte species.",
Arsenic,2279575,"Evaluation of urinary speciated arsenic in NHANES: Issues in interpretation in the context of potential inorganic arsenic exposure Abstract: Urinary dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) are among the commonly used biomarkers for inorganic arsenic (iAs) exposure, but may also arise from seafood consumption and organoarsenical pesticide applications. We examined speciated urinary arsenic data from National Health and Nutrition Examination Survey (NHANES) 2009-2010 cycle to assess potential correlations among urinary DMA, MMA, and the organic arsenic species arsenobetaine. Urinary DMA and MMA were positively associated with urinary arsenobetaine, suggesting direct exposure to these species in seafood or metabolism of organic arsenicals to these species, although the biomonitoring data do not directly identify the sources of exposure. The magnitude of association was much larger for DMA than for MMA. The secondary methylation index (SMI, ratio of urinary DMA to MMA) observed in the NHANES program likewise is much higher in persons with detected arsenobetaine than in those without, again suggesting that direct DMA exposure is co-occurring with exposure to arsenobetaine. Urinary MMA was less correlated with organic arsenic exposures than DMA and, therefore, may be a more reliable biomarker for iAs exposure in the general US population. However, given the associations between both MMA and DMA and organic arsenic species in urine, interpretations of the urinary arsenic concentrations observed in the NHANES in the context of potential arsenic exposure should be made cautiously.",
Arsenic,1797838,"Trends in arsenic levels in PM10 and PM 2.5 aerosol fractions in an industrialized area Abstract: Arsenic is a toxic element that affects human health and is widely distributed in the environment. In the area of study, the main Spanish and second largest European industrial ceramic cluster, the main source of arsenic aerosol is related to the impurities in some boracic minerals used in the ceramic process. Epidemiological studies on cancer occurrence in Spain points out the study region as one with the greater risk of cancer. Concentrations of particulate matter and arsenic content in PM10 and PM2.5 were measured and characterized by ICP-MS in the area of study during the years 2005-2010. Concentrations of PM10 and its arsenic content range from 27 to 46 ?g/m(3) and from 0.7 to 6 ng/m(3) in the industrial area, respectively, and from 25 to 40 ?g/m(3) and from 0.7 to 2.8 ng/m(3) in the urban area, respectively. Concentrations of PM2.5 and its arsenic content range from 12 to 14 ?g/m(3) and from 0.5 to 1.4 ng/m(3) in the urban background area, respectively. Most of the arsenic content is present in the fine fraction, with ratios of PM2.5/PM10 in the range of 0.65-0.87. PM10, PM2.5, and its arsenic content show a sharp decrease in recent years associated with the economic downturn, which severely hit the production of ceramic materials in the area under study. The sharp production decrease due to the economic crisis combined with several technological improvements in recent years such as substitution of boron, which contains As impurities as raw material, have reduced the concentrations of PM10, PM2.5, and As in air to an extent that currently meets the existing European regulations.",
Arsenic,2343432,"Child exposure to indoor and outdoor air pollutants in schools in Barcelona, Spain Abstract: Proximity to road traffic involves higher health risks because of atmospheric pollutants. In addition to outdoor air, indoor air quality contributes to overall exposure. In the framework of the BREATHE study, indoor and outdoor air pollution was assessed in 39 schools in Barcelona. The study quantifies indoor and outdoor air quality during school hours of the BREATHE schools. High levels of fine particles (PM2.5), nitrogen dioxide (NO2), equivalent black carbon (EBC), ultrafine particle (UFP) number concentration and road traffic related trace metals were detected in school playgrounds and indoor environments. PM2.5 almost doubled (factor of 1.7) the usual urban background (UB) levels reported for Barcelona owing to high school-sourced PM2.5 contributions: [1] an indoor-generated source characterised mainly by organic carbon (OC) from organic textile fibres, cooking and other organic emissions, and by calcium and strontium (chalk dust) and; [2] mineral elements from sand-filled playgrounds, detected both indoors and outdoors. The levels of mineral elements are unusually high in PM2.5 because of the breakdown of mineral particles during playground activities. Moreover, anthropogenic PM components (such as OC and arsenic) are dry/wet deposited in this mineral matter. Therefore, PM2.5 cannot be considered a good tracer of traffic emissions in schools despite being influenced by them. On the other hand, outdoor NO2, EBC, UFP, and antimony appear to be good indicators of traffic emissions. The concentrations of NO2 are 1.2 times higher at schools than UB, suggesting the proximity of some schools to road traffic. Indoor levels of these traffic-sourced pollutants are very similar to those detected outdoors, indicating easy penetration of atmospheric pollutants. Spatial variation shows higher levels of EBC, NO2, UFP and, partially, PM2.5 in schools in the centre than in the outskirts of Barcelona, highlighting the influence of traffic emissions. Mean child exposure to pollutants in schools in Barcelona attains intermediate levels between UB and traffic stations.",
Arsenic,711056,"Respiratory effect related to exposure of different concentrations of arsenic in drinking water in West Bengal, India Abstract: Arsenic toxicity due to drinking of arsenic contaminated water has been one of the worst environmental health hazards. High levels of arsenic have been reported in different natural water sources from West Bengal for more than two decades. Groundwater contamination by arsenic and its adverse effects on the health of a big population in nine districts of West Bengal have been reported. The problems found were mainly related to skin and respiratory, digestive, cardiovascular and nervous systems. The respiratory effects are largely confined to those who had the skin lesion. The present study was undertaken to evaluate the respiratory effects of exposure to different levels of arsenic in drinking water. The water samples were collected from different tube wells and wells in the study area. Analysis of arsenic was done by Atomic Absorption Spectrophotometer with hydride generation system. Based on the consumption of arsenic concentrations in drinking water the populations were divided into three categories, i.e., <=50 microg/L, >50 - <= 150 microg/L and >150 microg/L. Standard techniques of medical examination were applied to elicit signs and recorded in the pre-designed proforma. A written consent was taken from each subject for their voluntary participation in the study. 112 subjects were investigated. The respiratory effect was evaluated by measuring the pulmonary function test (PFT). Vital Capacity (VC) and Forced Vital Capacity (FVC) were measured by Spirovit-SP-10 (Schiller Health Care Pvt Ltd., Switzerland) and Peak Expiratory Flow Rate by Wrights Peak Flow Meter (Clement and Clarke, UK). The PFT values showed gradual decrement among the males following skin pigmentation, keratosis and arsenicosis. The respiratory function impairment among the male subjects found as restrictive type (26.41%), obstructive type (3.77%) and combined type (7.54%), whereas in females only the restrictive type of impairment (10.16%) was found. Restrictive type of impairments among the subjects increased as the concentration of arsenic in drinking water increased, in males 15.78%, 29.41% and 35.29% and in females 4.54%, 5.00% and 23.52% respectively. The pathophysiologic mechanism, by which ingested arsenic leads to impairments of lung function and increased respiratory symptoms, is yet to be understood and needs further investigation.",
Arsenic,1026544,"Icosahedral and ring-shaped allotropes of arsenic Abstract: We predict the existence of two novel families of arsenic nanostructures: icosahedral cages and ring-shaped chains. Quantum chemical calculations on the cages, rings, and the experimentally known allotropes of arsenic suggest the nanostructures to be thermodynamically stable. The icosahedral cages are modifications of the gray allotrope of arsenic, while the ring-shaped chains are structurally related to the red allotrope of phosphorus. Comparisons between the analogous allotropes of arsenic and phosphorus show distinct differences. While phosphorus favors the ring-shaped chains over the icosahedral cages, large cages become favorable for arsenic. From the thermodynamical point of view, experimental preparation of the proposed families of arsenic nanostructures is expected to be viable.",
Arsenic,1030290,"Urinary arsenic levels as an index of industrial exposure Abstract: Air analyses in a plant possibly generating arsine (7784421) reveal no excessive levels of arsenic (7440382) in workers' breathing zones, but urinary analyses show levels frequently exceeding 0.5 milligrams arsenic per liter urine. Investigation reveals elevated urinary arsenic in workers after eating seafood. Urinary arsenic levels are therefore not determined to provide a reliable index to industrial exposure, as no definite relationship can be shown between urinary arsenic levels and evidence of poisoning; urinary arsenic levels are useful in checking the efficacy of control measures and indicating excessive arsenic absorption whether due to industrial exposure or some outside source, as seafood in the diet.",
Arsenic,2088421,"Superoxide-Dismutase Deficient Mutants in Common Beans (Phaseolus vulgaris L.): Genetic Control, Differential Expressions of Isozymes, and Sensitivity to Arsenic Abstract: Two common bean (Phaseolus vulgaris L.) mutants, sodPv 1 and sodPv 2, exhibiting foliar superoxide dismutase (SOD) activity of only 25% and 40% of their mother control (MC) cv. VL 63 were isolated in EMS-mutagenized (0.15%, 8 h) M2 progeny. Native-PAGE analysis revealed occurrence of Mn SOD, Fe SOD, Cu/Zn SOD I and Cu/Zn SOD II isozymes in MC, while Fe SOD, and Mn SOD were not formed in sodPv 1 and sodPv 2 leaves, respectively. In-gel activity of individual isozymes differed significantly among the parents. SOD deficiency is inherited as recessive mutations, controlled by two different nonallelic loci. Gene expressions using qRT PCR confirmed higher expressions of Cu/Zn SOD transcripts in both mutants and the absence of Fe SOD in sodPv 1 and Mn SOD in sodPv 2. In 50??M arsenic, Cu/Zn SODs genes were further upregulated but other isoforms downregulated in the two mutants, maintaining SOD activity in its control level. In an F2 double mutants of sodPv 1 × sodPv 2, no Fe SOD, and Mn SOD expressions were detectable, while both Cu/Zn SODs are down-regulated and arsenic-induced leaf necrosis appeared. In contrast to both mutants, ROS-imaging study revealed overaccumulation of both superoxides and H2O2 in leaves of double mutant.",
Arsenic,656918,"Wild-type and Ras-transformed fibroblasts display differential mitogenic responses to transient sodium arsenite exposure Abstract: Arsenic is a human carcinogen whose mechanism of action remains undefined. Based on the hypothesis that arsenic sensitizes cells to mitogenic stimulation by affecting the receptor tyrosine kinase (RTK) signal transduction pathway, these studies first examined the response of fibroblasts to specific mitogens using a defined media system. In both rodent and human fibroblasts, DNA synthesis was found to be stimulated in cells exposed to a transient, sub-lethal concentration of sodium arsenite followed by stimulation with known RTK pathway activators. This effect is observed for up to 32 h after removal of arsenic, suggesting that the RTK pathway is affected in a sustained manner. In contrast, transient arsenic exposure of ras-transformed cells results in decreased mitogen-stimulated DNA synthesis. Flow cytometry indicates that arsenic increases the percentage of wild-type cells in the S-phase of the cell cycle; conversely, the percentage of ras-transformed cells in S-phase is decreased by arsenic. No evidence of arsenic-induced cytotoxicity was detected using the neutral red assay, ensuring that decreased DNA synthesis in ras-transformed cells is not due to cell death. Taken together, the results of experiments presented herein indicate that arsenic produces sustained alterations in the growth characteristics of rodent and human fibroblasts. It is postulated that the proliferation-enhancing effect of arsenic on wild-type cells contributes to its ability to cause cancer.",
Arsenic,2298742,"A mass spectrometric and quantum chemical study of the vaporisation of lead monoxide in a flow of gaseous arsenic and antimony trioxides Abstract: Mass spectrometric studies of the vapours over solid lead oxide in a flow of gaseous arsenic and antimony trioxides were conducted. The following ions of the ternary oxides were detected: Pb3As2O6(+), Pb3AsO4(+), PbAs2O4(+), PbAsO2(+), PbSb2O4(+), and PbSbO2(+). The origin of these species produced by the ionisation and/or fragmentation of ternary gaseous oxides is discussed. The PbAs2O4 species was undoubtedly identified by the determination of the appearance energy. Presumably, the Pb3As2O6 and PbSb2O4 species also existed in the gas phase. Thermodynamic data for the ternary oxides were obtained experimentally by means of a mass spectrometric Knudsen-cell method and were confirmed by quantum chemical calculations.",
Arsenic,1022147,"Identification of the GST-T1 and GST-M1 null genotypes using high resolution melting analysis Abstract: Glutathione S-transferases, including GST-T1 and GST-M1, are known to be involved in the phase II detoxification pathways for xenobiotics as well as in the metabolism of endogenous compounds. Polymorphisms in these genes have been linked to an increased susceptibility to carcinogenesis and associated with risk factors that predispose to certain inflammatory diseases. In addition, GST-T1 and GST-M1 null genotypes have been shown to be responsible for interindividual variations in the metabolism of arsenic, a known human carcinogen. To assess the specific GST genotypes in the Mexican population chronically exposed to arsenic, we have developed a multiplex High Resolution Melting PCR (HRM-PCR) analysis using a LightCycler480 instrument. This method is based on analysis of the PCR product melting curve that discriminates PCR products according to their lengths and base sequences. Three pairs of primers that specifically recognize GST-T1, GST-M1, and ?-globin, an internal control, to produce amplicons of different length were designed and combined with LightCycler480 High Resolution Melting Master Mix containing ResoLight, a completely saturating DNA dye. Data collected from melting curve analysis were evaluated using LightCycler480 software to determine specific melting temperatures of individual melting curves representing target genes. Using this newly developed multiplex HRM-PCR analysis, we evaluated GST-T1 and GST-M1 genotypes in 504 DNA samples isolated from the blood of individuals residing in Zimapan, Lagunera, and Chihuahua regions in Mexico. We found that the Zimapan and Lagunera populations have similar GST-T1 and GST-M1 genotype frequencies which differ from those of the Chihuahua population. In addition, 14 individuals have been identified as carriers of the double null genotype, i.e., null genotypes in both GST-T1 and GST-M1 genes. Although this procedure does not distinguish between biallelic (+/+) and monoallelic (+/-) genotypes, it can be used in an automated workflow as a simple, sensitive, and time and money saving procedure for rapid identification of the GST-T1 and GST-M1 positive or null genotypes.",
Arsenic,2149129,"Human exposure to arsenic from drinking water in Vietnam Abstract: Vietnam is an agricultural country with a population of about 88 million, with some 18 million inhabitants living in the Red River Delta in Northern Vietnam. The present study reports the chemical analyses of 68 water and 213 biological (human hair and urine) samples conducted to investigate arsenic contamination in tube well water and human arsenic exposure in four districts (Tu Liem, Dan Phuong, Ly Nhan, and Hoai Duc) in the Red River Delta. Arsenic concentrations in groundwater in these areas were in the range of <1 to 632?g/L, with severe contamination found in the communities Ly Nhan, Hoai Duc, and Dan Phuong. Arsenic concentrations were markedly lowered in water treated with sand filters, except for groundwater from Hoai Duc. Human hair samples had arsenic levels in the range of 0.07-7.51?g/g, and among residents exposed to arsenic levels ?50?g/L, 64% of them had hair arsenic concentrations higher than 1?g/g, which is a level that can cause skin lesions. Urinary arsenic concentrations were 4-435?g/g creatinine. Concentrations of arsenic in hair and urine increased significantly with increasing arsenic content in drinking water, indicating that drinking water is a significant source of arsenic exposure for these residents. The percentage of inorganic arsenic (IA) in urine decreased with age, whereas the opposite trend was observed for monomethylarsonic acid (MMA) in urine. Significant co-interactions of age and arsenic exposure status were also detected for concentrations of arsenic in hair and the sum of IA, MMA, and dimethylarsinic acid (DMA) in urine and %MMA. In summary, this study demonstrates that a considerable proportion of the Vietnamese population is exposed to arsenic levels of chronic toxicity, even if sand filters reduce exposure in many households. Health problems caused by arsenic ingestion through drinking water are increasingly reported in Vietnam.",
Arsenic,627199,"Physiologically based pharmacokinetic modeling of arsenic in the mouse Abstract: A remarkable feature of the carcinogenicity of inorganic arsenic is that while human exposures to high concentrations of inorganic arsenic in drinking water are associated with increases in skin, lung, and bladder cancer, inorganic arsenic has not typically caused tumors in standard laboratory animal test protocols. Inorganic arsenic administered for periods of up to 2 yr to various strains of laboratory mice, including the Swiss CD-1, Swiss CR:NIH(S), C57Bl/6p53(+/-), and C57Bl/6p53(+/+), has not resulted in significant increases in tumor incidence. However, Ng et al. (1999) have reported a 40% tumor incidence in C57Bl/6J mice exposed to arsenic in their drinking water throughout their lifetime, with no tumors reported in controls. In order to investigate the potential role of tissue dosimetry in differential susceptibility to arsenic carcinogenicity, a physiologically based pharmacokinetic (PBPK) model for inorganic arsenic in the rat, hamster, monkey, and human (Mann et al., 1996a, 1996b) was extended to describe the kinetics in the mouse. The PBPK model was parameterized in the mouse using published data from acute exposures of B6C3F1 mice to arsenate, arsenite, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) and validated using data from acute exposures of C57Black mice. Predictions of the acute model were then compared with data from chronic exposures. There was no evidence of changes in the apparent volume of distribution or in the tissue-plasma concentration ratios between acute and chronic exposure that might support the possibility of inducible arsenite efflux. The PBPK model was also used to project tissue dosimetry in the C57Bl/6J study, in comparison with tissue levels in studies having shorter duration but higher arsenic treatment concentrations. The model evaluation indicates that pharmacokinetic factors do not provide an explanation for the difference in outcomes across the various mouse bioassays. Other possible explanations may relate to strain-specific differences, or to the different durations of dosing in each of the mouse studies, given the evidence that inorganic arsenic is likely to be active in the later stages of the carcinogenic process.",
Arsenic,628488,"Prevalence of arsenic exposure and skin lesions. A population based survey in Matlab, Bangladesh Abstract: STUDY OBJECTIVE: To assess prevalence of arsenic exposure through drinking water and skin lesions, and their variation by geographical area, age, sex, and socioeconomic conditions. DESIGN, SETTING, AND PARTICIPANTS: Skin lesion cases were identified by screening the entire population above 4 years of age (n = 166,934) living in Matlab, a rural area in Bangladesh, during January 2002 and August 2003. The process of case identification involved initial skin examinations in the field, followed by verification by physicians in a clinic, and final confirmation by two independent experts reviewing photographs. The tubewell water arsenic concentrations (n = 13,286) were analysed by atomic absorption spectrometry. Drinking water history since 1970 was obtained for each person. Exposure information was constructed using drinking water histories and data on water arsenic concentrations. MAIN RESULTS: The arsenic concentrations ranged from <1 to 3644 microg/l, and more than 70% of functioning tubewells exceeded the World Health Organisation guideline of 10 microg/l. Arsenic exposure had increased steadily from 1970s to the late 1990s, afterwards a decrease could be noted. In total, 504 skin lesions cases were identified, and the overall crude prevalence was 3/1000. Women had significantly higher cumulative exposure to arsenic, while men had significantly higher prevalence of skin lesions (SMR 158, 95% CI 133 to 188). The highest prevalence occurred in 35-44 age groups for both sexes. Arsenic exposure and skin lesions had a positive association with socioeconomic groups and achieved educational level. CONCLUSIONS: The result showed sex, age, and socioeconomic differentials in both exposure and skin lesions. Findings clearly showed the urgency of effective arsenic mitigation activities.",
Arsenic,697765,"Identification of tumor promotion marker genes for predicting tumor promoting potential of chemicals in BALB/c 3T3 cells Abstract: Tumor promoters can cause development of tumors in initiated cells and the majority of them are non-genotoxic carcinogens. The detection of tumor promoters is important for the prevention of cancer. The in vitro two-stage transformation assay, using BALB/c 3T3 cells, is a useful system, and benefits from a convenient protocol and high predictability of mammalian carcinogenicity. But these assays are time-consuming and often require expertise for microscopic observation. To construct an in vitro tumor promoting activity test system, we performed large-scale gene expression analyses, using DNA microarrays, of BALB/c 3T3 cells following treatment with nine chemicals that are known to induce tumor promotion: TPA, zinc chloride, sodium orthovanadate, okadaic acid, insulin, lithocolic acid, phenobarbital sodium, sodium saccharide, sodium arsenite. As a result of DNA microarray and real time PCR analyses, 22 marker genes were identified. These consisted of genes related to cell cycle, regulation of transcription, anti-apoptosis, and positive regulation of cell proliferation. There was a correlation between these 22 marker genes and the cell transformation assay results in BALB/c 3T3 cells. These results suggest that this tumor promoting activity test system, based on 22 marker genes, can become a valuable tool for screening potential tumor promoters.",
Arsenic,2149344,Treatment of arsenic containing drinking waters by electrochemical oxidation and reverse osmosis Abstract: ,
Arsenic,2064232,"Fate of arsenate adsorbed on nano-TiO2 in the presence of sulfate reducing bacteria Abstract: Arsenic removal using nanomaterials has attracted increasing attention worldwide, whereas the potential release of As from spent nanomaterials to groundwater in reducing environments is presently underappreciated. This research investigated the fate of As(V) adsorbed on nano-TiO2 in the presence of sulfate reducing bacteria (SRB) Desulfovibrio vulgaris strains DP4 and ATCC 7757. The incubation results demonstrated that As(V) was desorbed from nano TiO2, and subsequently reduced to As(III) in aqueous solution. The release of adsorbed As(V) was two to three times higher in biotic samples than that in abiotic controls. Reduction of As(V) to As(III) in biotic samples was coupled with the conversion of sulfate to sulfide, while no As(III) was observed in abiotic controls. STXM results provided the direct evidence of appreciable As(III) and As(V) on TiO2. XANES analysis indicated that As(V) was the predominant species for three As loads of 150, 300, and 5700 mg/g, whereas 15-28% As precipitated as orpiment for a high As load of 5700 mg/g. In spite of orpiment formation, As mobilized in higher amounts in the SRB presence than in abiotic controls, highlighting the key role of SRB in the fate of As in the presence of nanomaterials.",
Arsenic,2347794,"Uranyl ions adsorption by novel metal hydroxides loaded Amberlite IR120 Abstract: In this work, Ni(OH)(2)-loaded Amberlite IR120 (Ni MA) and Co(OH)(2)-loaded Amberlite IR120 (Co MA) resins were prepared, characterized and applied for UO22+ removal from aqueous solutions. The adsorption characteristics were investigated in a batch system with respect to effect of contact time, pH, equilibrium isotherms and removal kinetics data. The results indicated that the LO22+ could be efficiently removed from aqueous solutions at pH = 3.5 using Ni MA and Co MA resins. The maximum adsorption capacities for the UO22+ of Ni MA and Co MA were found to be 439 mg/g and 451 mg/g respectively. The equilibrium data fit well with the Langmuir adsorption isotherm. Kinetics study showed that the adsorption process was fast and reached equilibrium within 60 min and the kinetics data fit well with pseudo-second order and intra-particle diffusion models for both resins. The adsorption mechanism has been proposed and discussed. It was found that both Ni MA and Co MA resins could be used effectively for UO22+ removal from aqueous solutions.",
Arsenic,1031815,"Relation of arsenic exposure to lung cancer among tin miners in Yunnan Province, China Abstract: The relation of mining and smelting exposure to arsenic and lung cancer was studied among tin miners in Yunnan Province in the People's Republic of China. Interviews were conducted in 1985 with 107 living tin miners who had lung cancer and an equal number of age matched controls from among tin miners without lung cancer to obtain information on risk factors for lung cancer including detailed history of employment and tobacco use. Occupational history was combined with industrial hygiene data to estimate cumulative arsenic exposure. Similar methods were also used to estimate radon exposure for simultaneous evaluation in this analysis. The results indicate that subjects in the highest quarter of cumulative arsenic exposure have a relative risk of 22.6 compared with subjects without exposure after adjusting for tobacco and radon exposure, and a positive dose response relation was observed. Simultaneous evaluation of arsenic and tobacco exposure indicates a greater risk for arsenic, whereas simultaneous assessment of arsenic and radon exposure suggests radon to be the greater risk. There is no evidence of synergism between arsenic and tobacco exposure. Among arsenic exposed individuals, cases of lung cancer have longer duration but lower average intensity of arsenic exposure than controls, indicating that duration of exposure to arsenic may be more important than intensity in the aetiology of lung cancer. Finally, risk of lung cancer among workers exposed to arsenic only in mining is only slightly less than for miners whose exposure to arsenic was limited to smelting, although risks are highest when workers were exposed to both mining and smelting.",
Arsenic,1016698,"Deprenyl, a therapeutic agent for Parkinson's disease, inhibits arsenic toxicity potentiated by GSH depletion via inhibition of JNK activation Abstract: Previously, studies reported that depletion of cellular GSH by sulfur amino acid deprivation (SAAD) potentiated arsenic (As)-induced cytotoxicity through activation of mitogen-activated protein (MAP) kinases. Deprenyl (selegiline), a selective inhibitor of monoamine oxidase B that is responsible for oxidative metabolism of dopamine, has been used as a therapeutic agent for the treatment of Parkinson's disease. This study investigated (1) whether deprenyl inhibited As-induced toxicity or As toxicity that was potentiated by glutathione (GSH) depletion and (2) whether deprenyl affected MAP kinase activation. Deprenyl protected H4IIE cells against the toxicity induced by As + SAAD in a concentration-dependent manner, but not by As alone. Activation of JNK by SAAD or As, but not that of p38 kinase or ERK1/2, was inhibited by treatment of cells with deprenyl. The cells that had been exposed to As or SAAD exhibited decreases in mitochondrial permeability to rhodamine 123, which was restored by deprenyl treatment or transfection with the plasmid encoding a dominant negative mutant of JNK [JNK1( )]. Transfection of H4IIE cells with the JNK1( ) plasmid, however, failed to protect cells against As toxicity. These results showed that deprenyl inhibits As toxicity potentiated by cellular GSH depletion, but not the toxicity induced by As alone. The cytoprotective effect of deprenyl may be mediated with restoration of mitochondrial function via its inhibition of JNK1.",
Arsenic,1704149,"Manganese and Arsenic Oxidation Performance of Bacterium-Yunotaki 86 (BY86) from Hokkaido, Japan, and the Bacterium's Phylogeny Abstract: ",
Arsenic,1797790,"Arsenic exposure associated with decreased bone mineralization in male Abstract: Objective: Arsenic (As) exposure may cause several medical problems. There were a few studies investigated whether it has affected bone tissue in women. However, there was no study in men. The aim of this study was to evaluate associations between bone mineral density (BMD) and As exposure in men subjects. Material and methods: We enrolled in this study 254 subjects who due to chronic As exposure suspected and 82 subjects as a control group. Hair As levels were detected by a hair analysis (Varian AA240Z Zeeman Atomic Absorption Spectrometer, USA). BMD measurements were obtained using dual-energy X-ray absorptiometry instrumentation. We investigated associations between the hair As levels and BMD measurements. Results: The frequency of osteoporosis and osteopenia was found to be 0.8% and 54.5%, respectively, in the As exposure group. The frequency of osteoporosis was found to be 1% and osteopenia was 32.4% in control subjects. There was significant difference between two groups (p?&lt;?0.001). Hair As level has a median 1.01 (min: 0.06 and max: 25.71). There were no significant correlation between hair As levels and BMD measurements. Conclusion: According to our observations, As exposure was associated with bone metabolism. Possible cause of osteopenia may be exposure to As. Further investigations are needed to estimate the relationship between As and bone metabolism.",
Arsenic,1348341,"ENHANCEMENT OF STRESS-INDUCED SYNTHESIS OF STRESS PROTEINS BY MASTOPARAN IN C6 RAT GLIOMA-CELLS Abstract: The levels of two small stress proteins, hsp27 and alpha B crystallin, were low in C6 glioma cells confluency. However, the levels of the two proteins increased after exposure of cells to heat (42 degrees C for 30 min) or arsenite (50-100 microM for 1 h) stress. When cells were exposed to arsenite or heat in the presence of mastoparan, a peptide toxin from wasp venom, the induction of hsp27 and alpha B crystallin was markedly stimulated, as detected by means of specific immunoassays, Western blot analysis, and Northern blot analysis. The response of hsp70 to each stress was also enhanced in the presence of mastoparan. Treatment of cells with 40 microM mastoparan alone barely induced the accumulation of hsp27 and alpha B crystallin. The stimulatory effect of mastoparan was little affected in cells that had been treated with pertussis toxin, but it was strongly suppressed in the presence of quinacrine, an inhibitor of phospholipase A2. These results suggest that mastoparan, which is an activator of phospholipase A2, enhances the responses to stress of hsp27, alpha B crystallin and hsp70 by increasing the metabolic activity of the arachidonic acid cascade.",
Arsenic,1422895,"Quality and mutagenicity of water and sediment of the streams impacted by the former uranium mine area Olší-Drahonín (Czech Republic) Abstract: The water quality research performed in the years 2003-2010 demonstrated an impact of the mine water pumped from the closed Olší uranium mine and discharged from the mine water treatment plant (MWTP) and groundwater from springs in the area on the water quality of the Had?vka stream. The water ecosystems of the lower part of the Had?vka stream are impacted mainly by water originated from the springs located in the stream valley and drained syenit subsoil, naturally rich in uranium. Those inflows caused a very high concentration of uranium measured in the water of the stream, which exceeds the given limit value. No negative impact on the water ecosystems of the receiving Bobr?vka River was found. This reduction of impact is caused by five times higher average daily flow rate of the Bobr?vka River in comparison with the Had?vka stream, which results in a sufficient dilution of pollution from the Had?vka.",
Arsenic,1032689,"Heat shock gene expression and cytoskeletal alterations in mouse neuroblastoma cells Abstract: The cytoskeleton of neuroblastoma cells, clone Neuro 2A, is altered by two stress conditions: heat shock and arsenite treatment. Microtubules are reorganized, intermediate filaments are aggregated around the nucleus, and the number of stress fibers is reduced. Since both stress modalities induce similar cytoskeletal alterations, no thermic denaturation of one or more cytoskeletal components can be involved in this process. Heat shock proteins are induced both by heat and by arsenite. However, cells treated with arsenite synthesize hsp28 which is not detected in heat-treated cells. Synthesis of all hsps is prevented by addition of actinomycin D or cycloheximide. Under these conditions no alterations are observed in the organization of microtubules and intermediate filaments during heat or arsenite treatment. However, these drugs are not able to prevent the rapid loss of stress fibers. A re-formation of the cytoskeleton during the recovery period proceeds within 3 h and is also found to occur in the presence of a protein synthesis inhibitor. These data suggest that reorganization of microtubules and intermediate filaments during a stress treatment requires the synthesis of a new protein(s), probably hsp(s).",
Arsenic,1519162,"Restoration of arsenite induced hepato-toxicity by crude tannin rich fraction of Theobroma cacao in Sprague Dawley rats Abstract: The present study was designed to investigate the protective efficacy of tannin rich cocoa (Theobroma cacao L.) in comparison with its detannified fraction. Arsenic as sodium-m-arsenite at 100 ppm dose was orally administered via drinking water constantly for 28 days to Sprague Dawley female rats. The hepatic cellular thiol levels such as total sulfhydryl content, protein bound sulfhydryl, non-protein bound sulfhydryl content, cellular oxidative stress and damage markers such as reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and the index of nitrite/nitrate (NOx) levels and a biomarker for arsenic toxicity namely delta-aminolevulinic acid dehydratase (ALAD) were substantially reduced and elevation of thiobarbituric acid reactive substances (TBARS) was observed in arsenic-exposed groups. The supplementation of tannin rich cocoa fraction (TCF) enhanced the levels of cellular thiols, markers of oxidative stress and levels of arsenic biomarkers and decreased the level of oxidative damage in treatment groups. Histopathologically, the liver of arsenic-exposed rats showed some degenerative lesions with few cells showing appearance of apoptosis which was effectively antagonized by tannin rich cocoa feeding. Treatment with detannified cocoa (DCF) was not that protective compared to the tannin rich cocoa (TCF). These results demonstrate that tannin rich cocoa can be considered as a functional food which effectively antagonizes many of the adverse effects of arsenic intoxication.",
Arsenic,2064155,The apoptotic effect and mechanism of arsenic compounds in MA-10 mouse Leydig tumor cells Abstract: ,
Arsenic,2064200,"Precipitation of alacranite (As8S9) by a novel As(V)-respiring anaerobe strain MPA-C3 Abstract: Strain MPA-C3 was isolated by incubating arsenic-bearing sediments under anaerobic, mesophilic conditions in minimal media with acetate as the sole source of energy and carbon, and As(V) as the sole electron acceptor. Following growth and the respiratory reduction of As(V) to As(III), a yellow precipitate formed in active cultures, while no precipitate was observed in autoclaved controls, or in uninoculated media supplemented with As(III). The precipitate was identified by X-ray diffraction as alacranite, As8 S9 , a mineral previously only identified in hydrothermal environments. Sequencing of the 16S rRNA gene indicated that strain MPA-C3 is a member of the Deferribacteres family, with relatively low (90%) identity to Denitrovibrio acetiphilus?DSM 12809. The arsenate respiratory reductase gene, arrA, was sequenced, showing high homology to the arrA gene of Desulfitobacterium halfniense. In addition to As(V), strain MPA-C3 utilizes NO3 (-) , Se(VI), Se(IV), fumarate and Fe(III) as electron acceptors, and acetate, pyruvate, fructose and benzoate as sources of carbon and energy. Analysis of a draft genome sequence revealed multiple pathways for respiration and carbon utilization. The results of this work demonstrate that alacranite, a mineral previously thought to be formed only chemically under hydrothermal conditions, is precipitated under mesophilic conditions by the metabolically versatile strain MPA-C3.",
Arsenic,1352045,Direct determination of impurities in arsenic by atomic spectrometry Abstract: ,
Arsenic,2337096,"Silicon has opposite effects on the accumulation of inorganic and methylated arsenic species in rice Abstract: Rice (Oryza sativa) is a main source of human exposure to inorganic arsenic and mitigation measures are needed to decrease As accumulation in this staple crop. It has been shown that silicon decreases the accumulation of arsenite but, unexpectedly, increases the accumulation of dimethylarsinic acid (DMA) in rice grain. The aim of this study was to investigate why Si increases DMA accumulation. <br> <br>Pot and incubation experiments were conducted to investigate how the addition of sparingly soluble silicate gel affected As speciation in the soil solution and the accumulation of different As species in rice tissues. <br> <br>Silicon addition significantly decreased the concentration of inorganic As (mainly arsenite) but increased the concentration of DMA in both the vegetative and reproductive tissues of rice. Silicon increased the concentration of DMA in the soil solution, whereas autoclaving soil decreased DMA concentration. Less DMA was adsorbed by the soil than arsenate and Si addition significantly inhibited DMA adsorption. <br> <br>Silicon increased DMA accumulation and decreased arsenite accumulation in rice through different mechanisms. Silicic acid released from the silicate gel increased the availability of DMA for rice uptake by inhibiting DMA adsorption on the soil solid phase or by displacing adsorbed DMA. Although silicic acid also increased the concentration of inorganic As in the soil solution, this effect was much smaller than the inhibitory effect of Si on arsenite uptake by rice roots.",
Arsenic,1003600,"Connection between multimetal(loid) methylation in methanoarchaea and central intermediates of methanogenesis Abstract: In spite of the significant impact of biomethylation on the mobility and toxicity of metals and metalloids in the environment, little is known about the biological formation of these methylated metal(loid) compounds. While element-specific methyltransferases have been isolated for arsenic, the striking versatility of methanoarchaea to methylate numerous metal(loid)s, including rare elements like bismuth, is still not understood. Here, we demonstrate that the same metal(loid)s (arsenic, selenium, antimony, tellurium, and bismuth) that are methylated by Methanosarcina mazei in vivo are also methylated by in vitro assays with purified recombinant MtaA, a methyltransferase catalyzing the methyl transfer from methylcobalamin [CH?Cob(III)] to 2-mercaptoethanesulfonic acid (CoM) in methylotrophic methanogenesis. Detailed studies revealed that cob(I)alamin [Cob(I)], formed by MtaA-catalyzed demethylation of CH?Cob(III), is the causative agent for the multimetal(loid) methylation observed. Moreover, Cob(I) is also capable of metal(loid) hydride generation. Global transcriptome profiling of M. mazei cultures exposed to bismuth did not reveal induced methyltransferase systems but upregulated regeneration of methanogenic cofactors in the presence of bismuth. Thus, we conclude that the multimetal(loid) methylation in vivo is attributed to side reactions of CH?Cob(III) with reduced cofactors formed in methanogenesis. The close connection between metal(loid) methylation and methanogenesis explains the general capability of methanoarchaea to methylate metal(loid)s.",
Arsenic,2343472,"Toxicity of arsenic species to three freshwater organisms and biotransformation of inorganic arsenic by freshwater phytoplankton (Chlorella sp. CE-35) Abstract: In the environment, arsenic (As) exists in a number of chemical species, and arsenite (As(III)) and arsenate (As(V)) dominate in freshwater systems. Toxicity of As species to aquatic organisms is complicated by their interaction with chemicals in water such as phosphate that can influence the bioavailability and uptake of As(V). In the present study, the toxicities of As(III), As(V) and dimethylarsinic acid (DMA) to three freshwater organisms representing three phylogenetic groups: a phytoplankton (Chlorella sp. strain CE-35), a floating macrophyte (Lemna disperma) and a cladoceran grazer (Ceriodaphnia cf. dubia), were determined using acute and growth inhibition bioassays (EC50) at a range of total phosphate (TP) concentrations in OECD medium. The EC50 values of As(III), As(V) and DMA were 27±10, 1.15±0.04 and 19±3mg L(-1) for Chlorella sp. CE-35; 0.57±0.16, 2.3±0.2 and 56±15mgL(-1) for L. disperma, and 1.58±0.05, 1.72±0.01 and 5.9±0.1mgL(-1) for C. cf. dubia, respectively. The results showed that As(III) was more toxic than As(V) to L. disperma; however, As(V) was more toxic than As(III) to Chlorella sp. CE-35. The toxicities of As(III) and As(V) to C. cf. dubia were statistically similar (p&gt;0.05). DMA was less toxic than iAs species to L. disperma and C. cf. dubia, but more toxic than As(III) to Chlorella sp. CE-35. The toxicity of As(V) to Chlorella sp. CE-35 and L. disperma decreased with increasing TP concentrations in the growth medium. Phosphate concentrations did not influence the toxicity of As(III) to either organism. Chlorella sp. CE-35 showed the ability to reduce As(V) to As(III), indicating a substantial influence of phytoplankton on As biogeochemistry in freshwater aquatic systems.",
Arsenic,628535,"Comparative toxicity of trivalent and pentavalent inorganic and methylated arsenicals in rat and human cells Abstract: Biomethylation is considered a major detoxification pathway for inorganic arsenicals (iAs). According to the postulated metabolic scheme, the methylation of iAs yields methylated metabolites in which arsenic is present in both pentavalent and trivalent forms. Pentavalent mono- and dimethylated arsenicals are less acutely toxic than iAs. However, little is known about the toxicity of trivalent methylated species. In the work reported here the toxicities of iAs and trivalent and pentavalent methylated arsenicals were examined in cultured human cells derived from tissues that are considered a major site for iAs methylation (liver) or targets for carcinogenic effects associated with exposure to iAs (skin, urinary bladder, and lung). To characterize the role of methylation in the protection against toxicity of arsenicals, the capacities of cells to produce methylated metabolites were also examined. In addition to human cells, primary rat hepatocytes were used as methylating controls. Among the arsenicals examined, trivalent monomethylated species were the most cytotoxic in all cell types. Trivalent dimethylated arsenicals were at least as cytotoxic as trivalent iAs (arsenite) for most cell types. Pentavalent arsenicals were significantly less cytotoxic than their trivalent analogs. Among the cell types examined, primary rat hepatocytes exhibited the greatest methylation capacity for iAs followed by primary human hepatocytes, epidermal keratinocytes, and bronchial epithelial cells. Cells derived from human bladder did not methylate iAs. There was no apparent correlation between susceptibility of cells to arsenic toxicity and their capacity to methylate iAs. These results suggest that (1) trivalent methylated arsenicals, intermediary products of arsenic methylation, may significantly contribute to the adverse effects associated with exposure to iAs, and (2) high methylation capacity does not protect cells from the acute toxicity of trivalent arsenicals.",
Arsenic,620260,"Arsenic-stimulated liver sinusoidal capillarization in mice requires NADPH oxidase-generated superoxide Abstract: Environmental arsenic exposure, through drinking contaminated water, is a significant risk factor for developing vascular diseases and is associated with liver portal hypertension, vascular shunting, and portal fibrosis through unknown mechanisms. We found that the addition of low doses of arsenite to the drinking water of mice resulted in marked pathologic remodeling in liver sinusoidal endothelial cells (SECs), including SEC defenestration, capillarization, increased junctional PECAM-1 expression, protein nitration, and decreased liver clearance of modified albumin. Furthermore, the pathologic changes observed after in vivo exposure were recapitulated in isolated mouse SECs exposed to arsenic in culture. To investigate the role of NADPH oxidase-generated ROS in this remodeling, we examined the effect of arsenite in the drinking water of mice deficient for the p47 subunit of the NADPH oxidase and found that knockout mice were protected from arsenite-induced capillarization and protein nitration. Furthermore, ex vivo arsenic exposure increased SEC superoxide generation, and this effect was inhibited by addition of a Nox2 inhibitor and quenched by the cellpermeant superoxide scavenger. In addition, inhibiting either oxidant generation or Rac1-GTPase blocked ex vivo arsenic-stimulated SEC differentiation and dysfunction. Our data indicate that a Nox2-based oxidase is required for SEC capillarization and that it may play a central role in vessel remodeling following environmentally relevant arsenic exposures. [ABSTRACT FROM AUTHOR] Copyright of Journal of Clinical Investigation is the property of American Society for Clinical Investigation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1026470,"Toenail arsenic levels among residents in Amami-Oshima Island, Japan Abstract: In order to evaluate the current arsenic exposure status and its determinants in Japan, we collected toenail samples from 212 subjects residing in a town with a population of 6,900 in Amami-Oshima Island in August 1999. We measured arsenic concentrations of the toenails using inductively coupled plasma mass spectrometry. In addition, we examined the association of arsenic levels with lifestyles and dietary habits, including the consumption of fish, seaweed, and rice. The mean toenail arsenic level was 0.41 ppm (95% confidence interval, 0.36-0.47), which was about 3-fold higher than those observed in other populations of mainland Kagoshima. Arsenic levels were elevated among current smokers (mean = 0.65; 95% confidence interval, 0.32-1.29) when compared with non-smokers (mean = 0.40; 95% confidence interval, 0.34-0.46), and among the residents consuming 4 bowls or more, of rice every day (mean = 1.97; 95% confidence interval, 0.25-15.75) when compared to residents consuming 3 bowls or less (mean = 0.39; 95% confidence interval, 0.34-0.45). Sex, age, alcohol intake, fish consumption, or seaweed consumption was not associated with toenail arsenic concentration. Further studies seem warranted to examine the cause of relatively high arsenic levels in our study area.",
Arsenic,1519079,"Levels of metallic elements and their potential relationships to cognitive function among elderly from Federal Land Development Authority (FELDA) settlement in Selangor Malaysia Abstract: Exposure to toxic metals and excessive amount of trace elements is a risk factor of cognitive decline. Continuous monitoring of these elements by the use of metabolically inactive tissues such as fingernails may help in taking preventive measures to delay the cognitive decline process. In this study, the cognitive function of 54 elderlies (60-72 years old) from FELDA Sungai Tengi, Selangor, was evaluated using the Malay version of Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). The levels of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn) in fingernail were detected using Inductively Coupled Plasma-Mass Spectrometry. Results showed that (92.6 %) our population was cognitively impaired based on the MoCA with mean score of 18.07?±?5.11. The mean level of elements in fingernails for As, Cd, Cu, Mn, Pb, and Zn were 16.68?±?3.52, 4.26?±?0.91, 4.81?±?1.16, 1.00?±?0.23, 1.83?±?0.47, and 40.86?±?10.81 ?g/g, respectively. Significant inverse correlations were observed between MoCA with age (r?=?-0.543, p?<?0.01), Cu level (r?=?-0.330, p?<?0.05), and Mn level (r?=?-0.496, p?<?0.01). MMSE was correlated to age (r?=?-0.346, p?<?0.05) only. In conclusion, besides aging, the progression of cognitive decline among the elderly FELDA population was associated with increased levels of copper and manganese.",
Arsenic,1019278,"Arsenite, arsenate and vanadate affect human erythrocyte membrane Abstract: Effects of arsenite, arsenate and vanadate on human erythrocyte membrane have been assessed according to their routes passing through the membrane, their binding modes to the membrane and their influences on membrane proteins and lipids. The uptake of arsenate (1.0 mM) by cells approached a limit with intracellular arsenic of about 0.2 mM in 5 h, and was strongly inhibited (approximately 95%) by 4,4'-diisothiocyano-2,2'-disulfonic stilbene (DIDS), indicating that arsenate, similar to vanadate, passed across the membrane through the anion exchange protein, band 3. Arsenite (1.0 mM) influx reached a maximum of about 0.4 mM in 30 min, and was not inhibited by DIDS. The transformed species of arsenite bound to the membrane from cytosol. In contrast, arsenate bound rapidly from the outside, followed by releasing and re-binding. The binding to the membrane via sulfhydryl was indicated by the decrease of the sulfhydryl level of membrane proteins. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS-PAGE) analysis revealed that the proteins, bands 1-3, were among the targets of arsenite, arsenate and vanadate. Their binding to the membrane also induced changes in the fluidity of membrane lipids and in the negative charge density in the outer surface of the membrane.",
Arsenic,2345781,"Effect of ultrasound on sodium arsenate induction time and crystallization property during solution crystallization processes Abstract: The effect of ultrasound vibrations on the cooling crystallization of sodium arsenate in supersaturated solutions was investigated. In particular, the effects of ultrasound vibrations on induction time and crystal size distribution were studied using a laser-based apparatus with relative supersaturation ranging from 1.3 to 1.8. The results show that ultrasound vibrations have a significant effect on reducing induction time and crystal size distribution. The application of ultrasound vibrations to the system resulted in a small change in surface tension; however, the induction time and crystal size significantly decreased. The mean size of sodium arsenate crystals decreased from 398.87 +/- 3.27 to 168.68 +/- 2.07 mu m, as the ultrasound power increases from 26 to 130 W. Ultrasound vibrations significantly reduced the induction time in a highly supersaturated solution compared to that in a low supersaturated solution.",
Arsenic,1381320,INCREASED BLADDER CELLS MICRONUCLEI IN TWO POPULATIONS ENVIRONMENTALLY EXPOSED TO ARSENIC IN DRINKING WATER Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE HUMAN GENOTOXICITY CARCINOGENICITY,
Arsenic,2337266,"There is still a care gap in osteoporosis management for patients with rheumatoid arthritis Abstract: <strong>OBJECTIVES: </strong>To assess compliance rates with the current Canadian osteoporosis guidelines and whether the Fracture Risk Assessment Tool score in patients with rheumatoid arthritis correlated with the likelihood of receiving osteoporosis treatment and having a bone mineral density test.<br /><br /><strong>METHODS: </strong>Charts of serial outpatients with rheumatoid arthritis were reviewed to collect bone mineral density test data and patients' use of calcium, vitamin D, and osteoporosis treatment. Odds ratios (OR) were calculated to determine if a higher Fracture Risk Assessment Tool score increased the likelihood of osteoporosis treatment or having a bone mineral density test.<br /><br /><strong>RESULTS: </strong>Using the Fracture Risk Assessment Tool, the 10-year risk of major osteoporotic fracture was high in 92 (12.5%), moderate in 216 (29.3%), and low in 429 (58.2%) patients. Compared to those at low risk, patients identified as high risk were more likely to receive osteoporosis treatment (OR 16.31, 95% CI 9.45-28.13, P&lt;0.001); calcium (OR 3.89, 95% CI 2.43-6.25, P&lt;0.001); vitamin D (OR 3.46, 95% CI 2.12-5.64, P&lt;0.001); and to have had a bone mineral density test (OR 10.22, 95% CI 5.50-18.96, P&lt;0.001). Among 124 patients currently taking prednisone, half (46.8%) were prescribed a bisphosphonate.<br /><br /><strong>CONCLUSIONS: </strong>Although compliance with current osteoporosis guidelines remains low among all patients with rheumatoid arthritis, higher risk patients were more likely to have a bone mineral density test and receive treatment for osteoporosis, as indicated by the clear dose response seen along the 10-year fracture risk from low to high-risk groups.",
Arsenic,1018178,"Status of groundwater arsenic contamination in Bangladesh: A 14-year study report Abstract: Since 1996, 52,202 water samples from hand tubewells were analyzed for arsenic (As) by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) from all 64 districts of Bangladesh; 27.2% and 42.1% of the tubewells had As above 50 and 10 ?g/l, respectively; 7.5% contained As above 300 ?g/l, the concentration predicting overt arsenical skin lesions. The groundwater of 50 districts contained As above the Bangladesh standard for As in drinking water (50 ?g/l), and 59 districts had As above the WHO guideline value (10 ?g/l). Water analyses from the four principal geomorphological regions of Bangladesh showed that hand tubewells of the Tableland and Hill tract regions are primarily free from As contamination, while the Flood plain and Deltaic region, including the Coastal region, are highly As-contaminated. Arsenic concentration was usually observed to decrease with increasing tubewell depth; however, 16% of tubewells deeper than 100 m, which is often considered to be a safe depth, contained As above 50 ?g/l. In tubewells deeper than 350 m, As &gt;50 ?g/l has not been found. The estimated number of tubewells in 50 As-affected districts was 4.3 million. Based on the analysis of 52,202 hand tubewell water samples during the last 14 years, we estimate that around 36 million and 22 million people could be drinking As-contaminated water above 10 and 50 ?g/l, respectively. However for roughly the last 5 years due to mitigation efforts by the government, non-governmental organizations and international aid agencies, many individuals living in these contaminated areas have been drinking As-safe water. From 50 contaminated districts with tubewell As concentrations &gt;50 ?g/l, 52% of sampled hand tubewells contained As &lt;10 ?g/l, and these tubewells could be utilized immediately as a source of safe water in these affected regions provided regular monitoring for temporal variation in As concentration. Even in the As-affected Flood plain, sampled tubewells from 22 thanas in 4 districts were almost entirely As-safe. In Bangladesh and West Bengal, India the crisis is not having too little water to satisfy our needs, it is the challenge of managing available water resources. The development of community-specific safe water sources coupled with local participation and education are required to slow the current effects of widespread As poisoning and to prevent this disaster from continuing to plague individuals in the future.",
Arsenic,1339782,"Rheumatoid factor determines structural progression of rheumatoid arthritis dependent and independent of disease activity Abstract: BACKGROUND: Rheumatoid factor (RF) is prototypic for rheumatoid arthritis (RA) and serves diagnostic and prognostic purposes. RF is associated with joint destruction, but the role of disease activity as a potential mediator of these effects has not been clearly elucidated yet. OBJECTIVE: To investigate if higher radiographic progression (Sharp score, ?TSS) in RF+ patients is dependent or independent of disease activity. METHODS: The authors performed a cross-sectional multivariate analysis at baseline and a matched cohort study in patients from five RA clinical trials. The authors pooled methotrexate treatment arms and compared ?TSS in RF+ and RF- patients before and after matching for other associated variables. RESULTS: Among 686 patients, 124 were RF- and 562 RF+, 343 having high (&gt;160 U/ml) RF. ?TSS was 1.03±5.83, 3.23±8.10 and 3.58±8.18 (p&lt;0.0001), respectively, and similarly for erosions and joint space narrowing (JSN). After matching for other prognostically important variables, ?TSS still was lower among 61 RF- versus 61 RF high+ patients (0.52±2.47 vs 3.09±8.28; p=0.028), mainly related to differences in erosion score (0.31±1.88 vs 2.07±5.62; p=0.035), but not JSN (0.21±1.26 vs 1.02±3.31; p=0.162). CONCLUSIONS: The data reveal that damage progression in seropositive RA patients is related to higher levels of disease activity and to independent effects of RF, particularly on bone damage. This calls for consideration of RF status irrespective of disease activity.",
Arsenic,1070400,"Arsenite activates NF?B through induction of C-reactive protein Abstract: C-reactive protein (CRP) is an acute phase protein in humans. Elevated levels of CRP are produced in response to inflammatory cytokines and are associated with atherosclerosis, hypertension, cardiovascular disease and insulin resistance. Exposure to inorganic arsenic, a common environmental toxicant, also produces cardiovascular disorders, namely atherosclerosis and is associated with insulin-resistance. Inorganic arsenic has been shown to contribute to cardiac toxicities through production of reactive oxygen species (ROS) that result in the activation of NF?B. In this study we show that exposure of the hepatic cell line, HepG2, to environmentally relevant levels of arsenite (0.13 to 2?M) results in elevated CRP expression and secretion. ROS analysis of the samples showed that a minimal amount of ROS are produced by HepG2 cells in response to these concentrations of arsenic. In addition, treatment of FvB mice with 100ppb sodium arsenite in the drinking water for 6months starting at weaning age resulted in dramatically higher levels of CRP in both the liver and inner medullary region of the kidney. Further, mouse Inner Medullary Collecting Duct cells (mIMCD-4), a mouse kidney cell line, were stimulated with 10ng/ml CRP which resulted in activation of NF?B. Pretreatment with 10 nM Y27632, a known Rho-kinase inhibitor, prior to CRP exposure attenuated NF?B activation. These data suggest that arsenic causes the expression and secretion of CRP and that CRP activates NF?B through activation of the Rho-kinase pathway, thereby providing a novel pathway by which arsenic can contribute to metabolic syndrome and cardiovascular disease.",
Arsenic,1239944,"Wet-chemical passivation of InAs: Toward surfaces with high stability and low toxicity Abstract: In a variety of applications where the electronic and optical characteristics of traditional, siliconbased materials are inadequate, recently researchers have employed semiconductors made from combinations of group III and V elements such as InAs. InAs has a narrow band gap and very high electron mobility in the near-surface region, which makes it an attractive material for high performance transistors, optical applications, and chemical sensing. However, silicon-based materials remain the top semiconductors of choice for biological applications, in part because of their relatively low toxicity. In contrast to silicon, InAs forms an unstable oxide layer under ambient conditions, which can corrode over time and leach toxic indium and arsenic components. To make InAs more attractive for biological applications, researchers have investigated passivation, chemical and electronic stabilization, of the surface by adlayer adsorption. Because of the simplicity, low cost, and flexibility in the type of passivating molecule used, many researchers are currently exploring wet-chemical methods of passivation. This Account summarizes much of the recent work on the chemical passivation of InAs with a particular focus on the chemical stability of the surface and prevention of oxide regrowth. We review the various methods of surface preparation and discuss how crystal orientation affects the chemical properties of the surface. The correct etching of InAs is critical as researchers prepare the surface for subsequent adlayer adsorption. HCl etchants combined with a postetch annealing step allow the tuning of the chemical properties in the near-surface region to either arsenic- or indium-rich environments. Bromine etchants create indium-rich surfaces and do not require annealing after etching; however, bromine etchants are harsh and potentially destructive to the surface. The simultaneous use of NH(4)OH etchants with passivating molecules prevents contact with ambient air that can occur during sample transfer between solutions. The passivation of InAs is dominated by sulfur-based molecules, which form stable In-S bonds on the InAs surface. Both sulfides and alkanethiols form well-defined monolayers on InAs and are dominated by In-S interactions. Sulfur-passivated InAs surfaces prevent regrowth of the surface oxide layer and are more stable in air than unpassivated surfaces. Although functionalization of InAs with sulfur-based molecules effectively passivates the surface, future sensing applications may require the adsorption of functional biomolecules onto the InAs surface. Current research in this area focuses on the passivation abilities of biomolecules such as collagen binding peptides and amino acids. These biomolecules can physically adsorb onto InAs, and they demonstrate some passivation ability but not to the extent of sulfur-based molecules. Because these adsorbents do not form covalent bonds with the InAs surface, they do not effectively block oxide regrowth. A mixed adlayer containing a biomolecule and a thiol on the InAs surface provides one possible solution: these hybrid surfaces enhance passivation but also maintain the presence of a biomolecule on the surface. Such surface functionalization strategies on InAs could provide long-term stability and make these surfaces suitable for biological applications.",
Arsenic,1508528,"Relationships between Heavy Metal Concentrations in Roadside Topsoil and Distance to Road Edge Based on Field Observations in the Qinghai-Tibet Plateau, China Abstract: This study investigated the spatial distribution of copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), chromium (Cr), cobalt (Co), nickel (Ni) and arsenic (As) in roadside topsoil in the Qinghai-Tibet Plateau and evaluated the potential environmental risks of these roadside heavy metals due to traffic emissions. A total of 120 topsoil samples were collected along five road segments in the Qinghai-Tibet Plateau. The nonlinear regression method was used to formulize the relationship between the metal concentrations in roadside soils and roadside distance. The Hakanson potential ecological risk index method was applied to assess the degrees of heavy metal contaminations. The regression results showed that both of the heavy metals' concentrations and their ecological risk indices decreased exponentially with the increase of roadside distance. The large R square values of the regression models indicate that the exponential regression method can suitably describe the relationship between heavy metal accumulation and roadside distance. For the entire study region, there was a moderate level of potential ecological risk within a 10 m roadside distance. However, Cd was the only prominent heavy metal which posed potential hazard to the local soil ecosystem. Overall, the rank of risk contribution to the local environments among the eight heavy metals was Cd &gt; As &gt; Ni &gt; Pb &gt; Cu &gt; Co &gt; Zn &gt; Cr. Considering that Cd is a more hazardous heavy metal than other elements for public health, the local government should pay special attention to this traffic-related environmental issue.",
Arsenic,1023979,"Chromium on the hands of children after playing in playgrounds built from chromated copper arsenate (CCA)-treated wood Abstract: Children's exposure to arsenic and chromium from playground equipment constructed with chromated copper arsenate (CCA)-treated wood is a potential concern because of children's hand-to-mouth activity. However, there exists no direct measure of Cr levels on the hands of children after playing in such playgrounds. In this study we measured both soluble and total Cr on the hands of 139 children playing in playgrounds, eight of which were constructed with CCA-treated wood and eight of which were not. Children's age and duration of play were recorded. The hands of each child were washed after play with 150 mL deionized water, which was collected in a bag and subsequently underwent analysis of Cr and 20 other elements, using inductively coupled plasma mass spectrometry. Total average Cr on the hands of 63 children who played in CCA playgrounds was 1,112 +/- 1,089 ng (median, 688; range 78-5,875). Total average Cr on the hands of 64 children who played in non-CCA playgrounds was 652 +/- 586 ng (median, 492; range 61-3,377). The difference between the two groups is statistically significant (p &lt; 0.01). Cr levels were highly correlated to both Cu (r = 0.672) and As (r = 0.736) levels in CCA playgrounds (p &lt; or = 0.01), but not non-CCA playgrounds (r = 0.252 and 0.486 for Cu and As, respectively). Principal-component analysis indicates that Cr, Cu, and As are more closely grouped together in CCA than in non-CCA playgrounds. These results suggest that the elevated levels of Cr and As on children's hands are due to direct contact with CCA wood.",
Arsenic,2149088,"Tracking of arsenics during the thermal stabilization of an AsH3 scrubber sludge Abstract: Toxic arsenics in an AsH3 scrubber sludge were thermally stabilized in the temperature range of 973-1,373 K. To better understand how the high-temperature treatments can stabilize arsenics in the sludge, their synchrotron X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra of arsenics were determined. It is found that the reduced arsenic leachability may be associated with the formation of As2O5 (51-59%) and embedded As(V) within the Ca3(PO4)2 matrix (41-49%) in the stabilized sludge. In addition, the As-O bond distances in the stabilized As2O5 are much less than that of normal As2O5 by 0.05-0.07 Å. The shorter As-O bond distances accompanied with the higher bonding energy also have a contribution to the thermal stabilization of arsenics.",
Arsenic,2347821,"Assessment of heavy metal residues in Brazilian poultry and swine tissue Abstract: The aim of this study was to investigate the presence of arsenic, lead and cadmium residues in samples of liver, kidney and muscle of poultry and swine during the years from 2002 to 2008. A total of 1978 samples were analyzed: 1031 of poultry and 947 of swine from Brazilian slaughterhouses. The samples were analyzed at the National Agricultural Laboratory using the atomic absorption spectrometry technique. In poultry, the arsenic residues were detected in 53.6% of liver samples, although no results have exceeded the MRL. In kidneys, 39.7% of the samples showed measurable residues and there was no violation of the limits. Regarding lead, there were 5 contaminated liver samples and 24 contaminated kidney samples (1.5 and 3.6% respectively). In muscle tissue there was only one sample with residues. For cadmium, 3.8% of the samples were found below MRL. Cadmium residues were found in 110 kidney samples (16.3% of tested), but only one exceeded the legislation limits. In swine, arsenic residues were detected in 15.3% of liver samples, although no results exceeded the MRL. In kidneys, 14.2% of samples showed measurable residues. However, there was no violation of limits. Regarding lead levels, 7 liver samples and 18 kidney samples were contaminated (2.6 and 2.7% respectively). Cadmium was found below MRL in 14.9% of the analyzed samples. In kidneys, 448 samples (67.8% of the total tested) had cadmium residues and 4 samples exceeded the legislation limits. During the seven years of study (2002-2008), only 5 (0.25%) out of 1978 tested samples violated the Brazilian law. However, even with low levels of violation, monitoring is essential, since the number of samples with residues was often greater than the number of violations, and in some cases, such as cadmium in the kidneys, the majority of samples contained quantifiable residues and with levels often near the limits.",
Arsenic,1337274,"Role of Pigment Epithelium-Derived Factor (PEDF) in Arsenic-Induced Cell Apoptosis of Liver and Brain in a Rat Model Abstract: Although studies have shown that arsenic exposure can induce apoptosis in a variety of cells, the exact molecular mechanism of chronic arsenicosis remains unclear. Based on our previous study on human serum, the present study was to determine whether pigment epithelium-derived factor (PEDF) plays a role in the damage induced by chronic arsenic exposure in a rat model and to explore the possible signaling pathway involved. Thirty male Wistar rats were randomly divided into three groups and the arsenite doses administered were 0, 10, and 50 mg/L, respectively. The experiment lasted for 6 months. Our results showed that level of arsenic increased significantly in serum, liver, brain, and kidney in arsenic-exposed groups. It was indicated that PEDF protein was widely distributed in the cytoplasm of various types of cells in liver, brain, and kidney. PEDF protein level was only changed when the arsenite dose reached 50 mg/L in liver and brain, whereas it was not changed in the kidney. In order to investigate the possible mechanism of PEDF-exerted damages upon arsenite exposure, apoptosis in liver and brain was assessed. The proportion of apoptotic cells gradually increased with increasing arsenic administration. The ratio of Bax/Bcl-2 in the high arsenic group (50 mg/L) was significantly higher than that in the control group. Therefore, we thought PEDF played a role in cell apoptosis of liver and brain which induced by sodium arsenite exposure, and the results also demonstrated that Bax and Bcl-2 might be two key targets in the action of PEDF.",
Arsenic,2278265,"Metagenome sequence analysis of filamentous microbial communities obtained from geochemically distinct geothermal channels reveals specialization of three Aquificales lineages Abstract: The Aquificales are thermophilic microorganisms that inhabit hydrothermal systems worldwide and are considered one of the earliest lineages of the domain Bacteria. We analyzed metagenome sequence obtained from six thermal “filamentous streamer” communities (?40 Mbp per site), which targeted three different groups of Aquificales found in Yellowstone National Park (YNP). Unassembled metagenome sequence and PCR-amplified 16S rRNA gene libraries revealed that acidic, sulfidic sites were dominated by Hydrogenobaculum (Aquificaceae) populations, whereas the circum-neutral pH (6.5–7.8) sites containing dissolved sulfide were dominated by Sulfurihydrogenibium spp. (Hydrogenothermaceae). Thermocrinis (Aquificaceae) populations were found primarily in the circum-neutral sites with undetectable sulfide, and to a lesser extent in one sulfidic system at pH 8. Phylogenetic analysis of assembled sequence containing 16S rRNA genes as well as conserved protein-encoding genes revealed that the composition and function of these communities varied across geochemical conditions. Each Aquificales lineage contained genes for CO2 fixation by the reverse-TCA cycle, but only the Sulfurihydrogenibium populations perform citrate cleavage using ATP citrate lyase (Acl). The Aquificaceae populations use an alternative pathway catalyzed by two separate enzymes, citryl-CoA synthetase (Ccs), and citryl-CoA lyase (Ccl). All three Aquificales lineages contained evidence of aerobic respiration, albeit due to completely different types of heme Cu oxidases (subunit I) involved in oxygen reduction. The distribution of Aquificales populations and differences among functional genes involved in energy generation and electron transport is consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, H2, O2) have resulted in niche specialization among members of the Aquificales.",
Arsenic,2337233,"Arsenic partitioning among particle-size fractions of mine wastes and stream sediments from cinnabar mining districts Abstract: Tailings from abandoned mercury mines represent an important pollution source by metals and metalloids. Mercury mining in Asturias (north-western Spain) has been carried out since Roman times until the 1970s. Specific and non-specific arsenic minerals are present in the paragenesis of the Hg ore deposit. As a result of intensive mining operations, waste materials contain high concentrations of As, which can be geochemically dispersed throughout surrounding areas. Arsenic accumulation, mobility and availability in soils and sediments are strongly affected by the association of As with solid phases and granular size composition. The objective of this study was to examine phase associations of As in the fine grain size subsamples of mine wastes (La Soterraña mine site) and stream sediments heavily affected by acid mine drainage (Los Rueldos mine site). An arsenic-selective sequential procedure, which categorizes As content into seven phase associations, was applied. In spite of a higher As accumulation in the finest particle-size subsamples, As fractionation did not seem to depend on grain size since similar distribution profiles were obtained for the studied granulometric fractions. The presence of As was relatively low in the most mobile forms in both sites. As was predominantly linked to short-range ordered Fe oxyhydroxides, coprecipitated with Fe and partially with Al oxyhydroxides and associated with structural material in mine waste samples. As incorporated into short-range ordered Fe oxyhydroxides was the predominant fraction at sediment samples, representing more than 80 % of total As.",
Arsenic,1344068,"Inferring mobility of trace elements resulting from long-term poultry litter additions to benchmark Alabama soils Abstract: Poultry litter when applied to agriculture lands contains high trace element concentrations that may become toxic to plants and pose a risk to surface water and groundwater. We evaluated whole soil elemental concentrations throughout the soil profile using the US Environmental Protection Agency digestion method 3052 for Alabama benchmark soils that had received more than 20 years of poultry litter. Paired soils that had not received poultry litter were equivalently characterized. Pairwise comparison tests indicate that trace element concentrations were significantly greater (P < 0.05) in poultry litter–amended soils than those in nonamended soils. Cadmium, As, Cu, Ni, and Cr concentrations significantly increased with soil profile depth relative to those in nonamended soils. Chromium concentration significantly increased from 38.8 mg kg?1 (0–15 cm) to 116 mg kg?1 (75–90 cm) in Malbis soil. The downward migration of these metals and metalloids may pose a risk to shallow groundwater resources and, if the soil is eroded, may pose a risk to surface water resources.",
Arsenic,1579238,"Construction of small plasmid vectors for use in genetic improvement of the extremely acidophilic Acidithiobacillus caldus Abstract: The genetic improvement of biomining bacteria including Acidithiobacillus caldus could facilitate the bioleaching process of sulfur-containing minerals. However, the available vectors for use in A. caldus are very scanty and limited to relatively large broad-host-range IncQ plasmids. In this study, a set of small, mobilizable plasmid vectors (pBBR1MCS-6, pMSD1 and pMSD2) were constructed based on plasmid pBBR1MCS-2, which does not belong to the IncQ, IncW, or IncP groups. The function of the tac promoter on 5.8-kb pMSD2 was determined by inserting a kanamycin-resistant reporter gene. The resulting recombinant pMSD2-Km was successfully transferred by conjugation into A. caldus MTH-04 with transfer frequency of 1.38±0.64×10(-5). The stability and plasmid copy number of pMSD2-Km in A. caldus MTH-04 were 75±2.7% and 5-6 copies per cell, respectively. By inserting an arsABC operon into pMSD2, an arsenic-resistant recombinant pMSD2-As was constructed and transferred into A. caldus MTH-04 by conjugation. The arsenic tolerance of A. caldus MTH-04 containing pMSD2-As was obviously increased up to 45mM of NaAsO2. These vectors could be applied in genetic improvement of A. caldus as well as other bioleaching bacteria.",
Arsenic,656649,"Keratin 6 expression correlates to areas of squamous differentiation in multiple independent isolates of As(+3)-induced bladder cancer Abstract: This laboratory has shown that arsenite (As(+3)) exposure can cause the malignant transformation of the UROtsa human urothelial cell line. This single isolate formed subcutaneous tumors with a histology similar to human urothelial cell carcinoma. The tumors also displayed areas of squamous differentiation of the urothelial cells, an infrequent but known component of human bladder cancer. In the present study, five additional independent isolates of As(+3)-transformed urothelial cells were isolated and each was shown to produce subcutaneous urothelial cell tumors with a characteristic histology very similar to those described in the initial report. That there were underlying phenotypic differences in the six independent isolates was demonstrated when they were assessed for their ability to form tumors within the peritoneal cavity. It was shown that two isolates could form hundreds of small peritoneal tumor nodules, one isolate a moderate number of tumor nodules, and three isolates no or only one tumor nodule. The peritoneal tumors were also characterized for their degree of squamous differentiation of the urothelial cells and, while areas of squamous differentiation could be found, such differentiation was substantially reduced compared to subcutaneous tumors. Immunostaining for keratin 6 was tested as a potential marker for malignant urothelial cells that had undergone squamous differentiation. Keratin 6 was shown to consistently stain only cells having some evidence of squamous differentiation. Keratin 16 was shown to follow the staining pattern of keratin 6. The isolates and tumor heterotransplants were all examined for keratin 6, 16 and 17 mRNA and protein expression.",
Arsenic,1034909,"DNA flow cytometry of the epidermis of patients with multiple epidermal carcinomas Abstract: We used DNA flow cytometry to determine whether the uninvolved skin of twenty-four patients with multiple epidermal cancers differed from normal skin with regard to its epidermal cell kinetics. We also studied the relationship between the cell kinetics and the type of cancer, previous exposure to ionizing or UV radiation, previous arsenic intake, skin type and coexisting psoriasis. Both exposed and unexposed skin was studied. In thirteen patients the S and G2M fractions of a monoclonal tumour were compared with the values in unexposed and exposed skin. The S and G2M fractions increased progressively from unexposed skin to exposed skin to tumour tissue. Patients who had developed both squamous and basal cell carcinoma differed from those who had developed only basal cell carcinoma by having a significantly higher G2M fraction in the exposed skin, and significantly higher S and G2M fractions in the unexposed skin. Patients exposed to ionizing radiation tended to show higher G2M fractions in exposed skin compared with the remaining individuals (P = 0.06). The presence of psoriasis, exposure to UVR or sunlight and previous arsenic ingestion did not appear to affect the results.",
Arsenic,467931,"Reactive oxygen species regulate properties of transformation in UROtsa cells exposed to monomethylarsonous acid by modulating MAPK signaling Abstract: UROtsa cells exposed to 50 nM monomethylarsonous acid [MMA(III)] for 52 wk (MSC52) achieved hyperproliferation, anchorage independent growth, and enhanced tumorgenicity. MMA(III) has been shown to induce reactive oxygen species (ROS), which can lead to activation of signaling cascades causing stress-related proliferation of cells and even cellular transformation. Previous research established the acute activation of MAPK signaling cascade by ROS produced by MMA(III) as well as chronic up regulation of COX-2 and EGFR in MSC52 cells. To determine if ROS played a role in the chronic pathway perturbations by acting as secondary messengers, activation of Ras was determined in UROtsa cells [exposed to MMA(III) for 0-52 wk] and found to be increased through 52 wk most dramatically after 20 wk of exposure. Ras has been shown to cause an increase in O-2(-) and be activated by increases in 02, making ROS important to study in the transformation process. COX-2 upregulation in MSC52 cells was confirmed by real time RT-PCR. By utilizing both antioxidants or specific COX inhibitors, it was shown that COX-2 upregulation was dependent on ROS, specifically, O-2(-). In addition, because previous research established the importance of MAPK activation in phenotypic changes associated with transformation in MSC52 cells, it was hypothesized that ROS play a role in maintaining phenotypic characteristics of the malignant transformation of MSC52 cells. Several studies have demonstrated that cancer cells have lowered superoxide dismutase (MnSOD) activity and protein levels. Increasing levels of MnSOD have been shown to suppress the malignant phenotype of cells. SOD was added to MSC52 cells resulting in slower proliferation rates (doubling time = 42 h vs. 31 h). ROS scavengers of (OH)-O-center dot also slowed proliferation rates of MSC52 cells. To further substantiate the importance of ROS in these properties of transformation in MSC52 cells, anchorage independent growth was assessed after the addition of antioxidants, both enzymatic and non-enzymatic. Scavengers of (OH)-O-center dot, and O-2(-) blocked the colony formation of MSC52 cells. These data support the role for the involvement of ROS in properties of transformation of UROtsa cells exposed to MMA(III). (C) 2008 Elsevier Ireland Ltd. All rights reserved.",
Arsenic,627251,"Defective ?1-integrins expression in arsenical keratosis and arsenic-treated cultured human keratinocytes Abstract: <strong>BACKGROUND: </strong>beta1-integrins, which localize to the basolateral surface of basal keratinocytes, are important in the differentiation control and proliferation of the epidermis. Many cutaneous diseases with perturbed differentiation, including arsenical keratosis, show altered patterns of integrin distribution and expression. Arsenic may induce arsenical keratosis through the differentiation and apoptosis aberration by integrins. The purpose of this study is to investigate the role of integrin and arsenic in the pathogenesis of arsenical keratosis.<br /><br /><strong>METHODS: </strong>Twenty-five specimens obtained from 25 patients with arsenical keratosis disease were studied. Immunohistochemistry staining to beta1, alpha2beta1, or alpha3beta1 integrins was performed in arsenical keratosis and clinically normal perilesional skin. Western blotting was used to assess the expression of integrin beta1 and focal adhesion kinase (FAK) in arsenic-treated cultured keratinocytes.<br /><br /><strong>RESULTS: </strong>A decreased expression of beta1, alpha2beta1, or alpha3beta1 integrins was demonstrated in arsenical keratosis and clinical normal perilesional skin in a large proportion of arsenical keratosis cases studied. The expressions of integrin beta1 and FAK were both decreased in arsenic-treated keratinocytes.<br /><br /><strong>CONCLUSIONS: </strong>Our results suggest that arsenic induces abnormal differentiation in arsenical keratosis via the effects of integrin expression in keratinocytes.",
Arsenic,1337487,"Infection with high-risk HPV types among female sex workers in northern Vietnam Abstract: Vaccines against two high-risk human papillomavirus (HPV) types, HPV-16, and HPV-18, are in use currently, with high efficacy for preventing infections with these HPV types and consequent cervical cancers. However, circulating HPV types can vary with geography and ethnicity. The aim of this study was to investigate the prevalence of HPV types and the association between HPV types and abnormal cervical cytology among female sex workers in Northern Vietnam. Cervical swabs and plasma samples were collected from 281 female sex workers at two health centers in Hanoi and Hai Phong in 2009. The HPV L1 gene was amplified by PCR using original and modified GP5(+) /6(+) primers. Amplified PCR products were genotyped by the microarray system GeneSquare (KURABO) and/or clonal sequencing. Of the 281 women, 139 (49.5%) were positive for HPV DNA. Among the HPV-positive samples, 339 strains and 29 different types were identified. Multiple-type and high risk-type HPV infections were found in 85 (61.2%) and 124 (89.2%) women, respectively. The most common genotype was HPV-52, followed by HPV-16, HPV-18, and HPV-58. Abnormal cervical cytology was detected in 3.2% (9/281) of the women, and all of these samples were positive for HPV-DNA. Age ?25 years and infection with human immunodeficiency virus were associated positively with HPV infection among the women while ever smoking was associated negatively. These results show that HPV-52 is most prevalent among female sex workers in Northern Vietnam, most of whom had normal cervical cytology. This information may be important for designing vaccination strategies in Vietnam. J. Med. Virol. 85:288-294, 2013. © 2012 Wiley Periodicals, Inc.",
Arsenic,628089,"Incidence of internal cancers and ingested inorganic arsenic: A seven-year follow-up study in Taiwan Abstract: In order to elucidate the dose-response relationship between ingested inorganic arsenic and internal cancers, a total of 263 patients with blackfoot disease and 2293 healthy residents in the endemic area of arseniasis were recruited and followed up for 7 years. The information on consumption of high-arsenic artesian well water, sociodemographic characteristics, life-style and dietary habits, and personal and family history of cancers was obtained through standardized interviews. The occurrence of internal cancers among study subjects was determined through annual health examinations, home visit personal interviews, household registration data checks, and national death certification and cancer registry profile linkages. A dose-response relationship was observed between the long-term arsenic exposure from drinking artesian well water and the incidence of lung cancer, bladder cancer, and cancers of all sites combined after adjustment for age, sex, and cigarette smoking through Cox's proportional hazards regression analysis. Blackfoot disease patients had a significantly increased cancer incidence after adjustment for cumulative arsenic exposure.",
Arsenic,1508635,"Deposition and uptake of metals in urban canopy: Atmospheric arsenic sequestration Abstract: The present study deals with quantifying the effectiveness of tree species in capturing atmospheric particulates and accumulating toxic elements like arsenic. This was achieved by analyzing the exposed leaves of six tree species (Ficus bengalensis, Ficus religiosa, Polyalthia longifolia, Anthocephalus cadamba, Putranjiva roxburghii, Alstonia scholaris) and foliar dusts deposited on those leaf surfaces for elemental content in Kolkata Metropolis, India. Morphology of leaf surface and chemical composition of foliar dust were examined using ESEM-EDAX. Amount of foliar dust is generally higher on adaxial surface in which agglomerates of atmospheric particulates cause clogging of stomata. Elemental composition in foliar dusts and canopy leaves were separately analyzed by EDXRF technique. Among the trace elements, heavy metals were found in considerable amount in the order Al&gt;Zn&gt;Pb&gt;Cu&gt;As&gt;Cd&gt;Co. Factor analysis suggests that co-associated, metallic elements are emitted as vehicle-derived pollutants as well as diffuse industrial emissions. Particulate arsenic is likely associated with combustion-derived materials and smelting operations. Significantly correlated arsenic between foliar dusts and plant leaves suggest atmospheric contamination to the urban ecosystem. P. roxburghii, A. cadamba and P. longifolia exhibited higher content of toxic metals including arsenic indicating their higher uptake capacity. The effectiveness of tree species in accumulating atmospheric particulates, particularly sequestration of atmospheric metals is the main outcome of this study.",
Arsenic,1794830,"IFEH 12th World Congress on Environmental Health, Vilnius, Lithuania, 22-27 May 2012 Heavy metals in biological samples of Moscow children and blood pressure levels Abstract: ",
Arsenic,1340003,"Modeling arsenite oxidation by chemoautotrophic Thiomonas arsenivorans strain b6 in a packed-bed bioreactor Abstract: Arsenic is a major toxic pollutant of concern for the human health. Biological treatment of arsenic contaminated water is an alternative strategy to the prevalent conventional treatments. The biological treatment involves a pre-oxidation step transforming the most toxic form of arsenic, As (III), to the least toxic form, As (V), respectively. This intermediate process improves the overall efficiency of total arsenic removal from the contaminated water. As (III) oxidation by the chemoautotrophic bacterium Thiomonas arsenivorans strain b6 was investigated in a fixed-film reactor under variable influent As (III) concentrations (500-4000 mg/L) and hydraulic residence times (HRTs) (0.2-1 day) for a duration of 137 days. During the entire operation, seven steady-state conditions were obtained with As (III) oxidation efficiency ranging from 48.2% to 99.3%. The strong resilience of the culture was exhibited by the recovery of the bioreactor from an As (III) overloading of 5300±400 mg As (III)/L day operated at a HRT of 0.2 day. An arsenic mass balance revealed that As (III) was mainly oxidized to As (V) with unaccounted arsenic (?4%) well within the analytical error of measurement. A modified Monod flux expression was used to determine the biokinetic parameters by fitting the model against the observed steady-state flux data obtained from operating the bioreactor under a range of HRTs (0.2-1 day) and a constant influent As (III) concentration of 500 mg/L. Model parameters, k=0.71±0.1 mg As (III)/mg cells h, and K(s)=13.2±2.8 mg As (III)/L were obtained using a non-linear estimation routine and employing the Marquardt-Levenberg algorithm. Sensitivity analysis revealed k to be more sensitive to model simulations of As (III) oxidation under steady-state conditions than parameter K(s).",
Arsenic,2347704,"Concentration of bioaerosols in composting plants using different quantification methods Abstract: <strong>BACKGROUND: </strong>Bioaerosols (organic dusts) containing viable and non-viable microorganisms and their metabolic products can lead to adverse health effects in exposed workers. Standard quantification methods of airborne microorganisms are mainly based on cultivation, which often underestimates the microbial burden. The aim of the study was to determine the microbial load in German composting plants with different, mainly cultivation-independent, methods. Second purpose was to evaluate which working areas are associated with higher or lower bioaerosol concentrations.<br /><br /><strong>METHODS: </strong>A total of 124 inhalable dust samples were collected at different workplaces in 31 composting plants. Besides the determination of inhalable dust, particles, and total cell numbers, antigen quantification for moulds (Aspergillus fumigatus, Aspergillus versicolor, Penicillium chrysogenum, and Cladosporium spp.) and mites was performed. Concentrations of ?-glucans as well as endotoxin and pyrogenic activities were also measured. The number of colony forming units (cfu) was determined by cultivation of moulds and actinomycetes in 36 additional dust samples.<br /><br /><strong>RESULTS: </strong>With the exception of particle numbers, concentrations of all determined parameters showed significant correlations (P &lt; 0.0001; r Spearman: 0.40-0.80), indicating a close association between these exposure markers. Colony numbers of mesophilic moulds and actinomycetes correlated also significantly with data of cultivation-independent methods. Exposure levels showed generally large variations. However, all parameters were measured highest in dusty working areas like next to the shredder and during processing with the exception of Cladosporium antigens that were found in the highest concentrations in the delivery area. The lowest concentrations of dust, particles, antigens, and pyrogenic activity were determined in wheel loader cabins (WLCs), which were equipped with an air filtration system.<br /><br /><strong>CONCLUSION: </strong>It was possible to assess the microbial load of air in composting plants with different quantification methods. Since allergic and toxic reactions may be also caused by nonliving microorganisms, cultivation-independent methods may provide additional information about bioaerosol composition. In general, air filtration reduced the bioaerosol exposure shown in WLCs. Due to the fact that the mechanical processing of compost material, e.g. by shredding or sieving is associated with the generation of high bioaerosol concentrations, there is still a need of improved risk assessment and state-of-the-art protective measures in composting plants.",
Arsenic,1016976,"Sodium arsenite inhibits and reverses expression of adipogenic and fat cell-specific genes during in vitro adipogenesis Abstract: Arsenic causes cancer in humans, but its mechanism of action is unique among known carcinogenic agents. As a naturally occurring component of sediments and ground water, human exposure to arsenic is inevitable, necessitating the establishment of exposure limits. Because cancer is characterized as an imbalance between cell growth and differentiation, it has been hypothesized that arsenic exerts its carcinogenic effect, in part, by perturbing the balance between these antagonistic processes. Previous work in this laboratory has demonstrated that sodium arsenite prevents adipocytic differentiation of C3H 10T1/2 cells, leading to the hypothesis that the underlying mechanism involves downregulation of genes associated with adipogenesis. In support of this hypothesis, it was found that mRNA levels of peroxisome proliferative-activated receptor gamma (PPAR gamma), CCAAT-enhancer binding protein alpha (C/EBP alpha), and adipocyte-selective, fatty acid-binding protein (aP2) are decreased in arsenic-treated cells; arsenic-induced phenotypic reversion of differentiated adipocytes correlates with reduced aP2 expression. Arsenic also blocks upregulation of p21(Cip1/Waf1), a factor whose expression is tightly regulated during adipogenesis. The differentiating effect of pioglitazone, which induces adipogenesis by activating PPAR gamma, is inhibited by arsenic, suggesting that arsenic interferes with adipogenic signaling at or below the level of PPAR gamma. Because C/EBP alpha is important in the expression of certain keratinocyte-specific genes, the negative effect of arsenic on C/EBP alpha might also contribute to the development of skin cancer. PPAR gamma, C/EBP alpha, and p21(Cip1/Waf1) are important in numerous normal and pathological processes, including carcinogenesis, leading us to postulate that perturbation of these factors by arsenic might contribute to the carcinogenic effect of this metalloid.",
Arsenic,2088472,"Arsenic exposure alters expression of cell cycle and lipid metabolism genes in the liver of adult zebrafish (Danio rerio) Abstract: Adult zebrafish (Danio rerio) were used to investigate mRNA expression in the liver following 7-day and 21-day exposures to 0, 10, 50, or 500ppb sodium arsenite. Arsenic exposure has been linked to several human disorders including cancers and cardiovascular and metabolic diseases. Quantitative PCR was employed to determine the mRNA expression of genes involved in cell cycle regulation [cyclin E1 (ccne1), WEE1 A kinase (wee1)], DNA damage repair [breast cancer 2 (brca2)] and lipid transport and metabolism [carnitine O-octanoyltransferase (crot), fatty acid binding protein-3 (fabp3) and 3-hydroxy-3-methylglutaryl-CoA synthase 1 (hmgcs1)]. Results from the 7-day exposure showed sex- and dose-specific changes in expression of wee1, brca2, crot and hmgcs1. No significant differences from controls were observed in fish exposed for 21 days. Expression of all genes, except ccne1, was significantly different between the 7- and 21-day exposures. The results presented here correlate with prior findings from our lab and others, and offer further insight into potential mechanisms of low-dose arsenic exposure.",
Arsenic,2149117,"In Bangladesh, funds dry up for arsenic mitigation research Abstract: ",
Arsenic,1255518,"Linking geochemical processes in mud volcanoes with arsenic mobilization driven by organic matter Abstract: The present study deals with geochemical characterization of mud fluids and sediments collected from Kunshuiping (KSP), Liyushan (LYS), Wushanting (WST), Sinyangnyuhu (SYNH), Hsiaokunshui (HKS) and Yenshuikeng (YSK) mud volcanoes in southwestern Taiwan. Chemical constituents (cations, anions, trace elements, organic carbon, humic acid, and stable isotopes) in both fluids and mud were analyzed to investigate the geochemical processes and spatial variability among the mud volcanoes under consideration. Analytical results suggested that the anoxic mud volcanic fluids are highly saline, implying connate water as the probable source. The isotopic signature indicated that ?(18)O-rich fluids may be associated with silicate and carbonate mineral released through water-rock interaction, along with dehydration of clay minerals. Considerable amounts of arsenic in mud irrespective of fluid composition suggested possible release through biogeochemical processes in the subsurface environment. Sequential extraction of As from the mud indicated that As was mostly present in organic and sulphidic phases, and adsorbed on amorphous Mn oxyhydroxides. Volcanic mud and fluids are rich in organic matter (in terms of organic carbon), and the presence of humic acid in mud has implications for the binding of arsenic. Functional groups of humic acid also showed variable sources of organic matter among the mud volcanoes being examined. Because arsenate concentration in the mud fluids was found to be independent from geochemical factors, it was considered that organic matter may induce arsenic mobilization through an adsorption/desorption mechanism with humic substances under reducing conditions. Organic matter therefore plays a significant role in the mobility of arsenic in mud volcanoes.",
Arsenic,1339334,"Computerized modeling of adenosine triphosphate, adenosine triarsenate and adenosine trivanadate Abstract: Computerized molecular models of adenosine triphosphate, adenosine tri-arsenate and adenosine trivanadate have been generated using the molecular mechanics technique. The analysis of structural parameters indicated that, at least theoretically, adenosine triarsenate is a realistic candidate for replacement of adenosine triphosphate in biochemical pathways. On the contrary, the structural arrangement of the inorganic segment of adenosine trivanadate does not seem to be capable of withstanding a swift hydrolytical splitting in aqueous milieu. It was shown that the universal force field as implemented in Gaussian software packages is an appropriate tool for the optimization of less-common bioactive compositions.",
Arsenic,627157,"Neurologic evaluation of a population exposed to arsenic in Alaskan well water Abstract: One hundred forty-seven persons exposed to arsenic from well water were evaluated by neurologic examination and nerve conduction studies. Total arsenic concentrations in well water ranged from 1 to 4781 micrograms/L and from 6 to 4964 micrograms/L in urine; a calculated index of arsenic ingestion ranged from 1 to 4521 micrograms/day. No dose-response relationship existed between arsenic ingestion and symptoms or physical findings compatible with peripheral neuropathy. Five of six persons with symptoms or physical findings suggestive of sensory neuropathy had normal nerve conduction velocities. Thirteen persons with elevated arsenic ingestion but no signs or symptoms of neuropathy had one or more abnormal nerve conduction velocities. No dose-response relationship, however, existed between arsenic ingestion and nerve conduction velocities. The authors concluded that arsenic ingestion from well water at the concentrations found in this Alaskan community did not result in clinical or subclinical neuropathy.",
Arsenic,2064271,"Compartmentation and complexation of metals in hyperaccumulator plants Abstract: Hyperaccumulators are being intensely investigated. They are not only interesting in scientific context due to their &quot;strange&quot; behavior in terms of dealing with high concentrations of metals, but also because of their use in phytoremediation and phytomining, for which understanding the mechanisms of hyperaccumulation is crucial. Hyperaccumulators naturally use metal accumulation as a defense against herbivores and pathogens, and therefore deal with accumulated metals in very specific ways of complexation and compartmentation, different from non-hyperaccumulator plants and also non-hyperaccumulated metals. For example, in contrast to non-hyperaccumulators, in hyperaccumulators even the classical phytochelatin-inducing metal, cadmium, is predominantly not bound by such sulfur ligands, but only by weak oxygen ligands. This applies to all hyperaccumulated metals investigated so far, as well as hyperaccumulation of the metalloid arsenic. Stronger ligands, as they have been shown to complex metals in non-hyperaccumulators, are in hyperaccumulators used for transient binding during transport to the storage sites (e.g., nicotianamine) and possibly for export of Cu in Cd/Zn hyperaccumulators [metallothioneins (MTs)]. This confirmed that enhanced active metal transport, and not metal complexation, is the key mechanism of hyperaccumulation. Hyperaccumulators tolerate the high amount of accumulated heavy metals by sequestering them into vacuoles, usually in large storage cells of the epidermis. This is mediated by strongly elevated expression of specific transport proteins in various tissues from metal uptake in the shoots up to the storage sites in the leaf epidermis. However, this mechanism seems to be very metal specific. Non-hyperaccumulated metals in hyperaccumulators seem to be dealt with like in non-hyperaccumulator plants, i.e., detoxified by binding to strong ligands such as MTs.",
Arsenic,1339137,"Fish consumption, fish atopy and related heavy metals in childhood eczema Abstract: Due to increasing worldwide water pollution, fish might be a source of excessive zinc, mercury, arsenic or manganese intake. The aim of this study was to evaluate if fish atopy/sensitization and fish consumption behavior are associated with eczema severity and blood levels of the 4 heavy metals.One-hundred and nineteen patients with eczema and 43 patients with miscellaneous non-eczema skin diseases were studied. There were no differences in average weekly fish consumption and blood levels of the 4 heavy metals between eczema and non-eczema groups. Blood levels of these metals were generally within the upper limits of local reference ranges in all these patients. In eczema patients, freshwater fish consumption behavior in days-per-week was correlated with blood arsenic and mercury levels (rho=0.17, p<0.01 for both metals), but not with zinc or manganese. Levels of arsenic and mercury were also correlated with days of seawater fish consumption per week (arsenic: 0.38, mercury: 0.24, p <0.05).Fish sensitization was present in 25% of patients with eczema. Nevertheless, there was no difference in terms of fish consumption behavior, eczema severity, quality of life, and heavy metal levels between eczema patients with or without fish sensitization. We conclude that without exceeding local normal reference ranges, blood arsenic and mercury levels correlated with fish consumption behavior. There is no evidence to suggest that fish sensitization is associated with more severe eczema (bad for eczema), or that patients have milder eczema with more days of fish consumption (good for eczema).",
Arsenic,1026432,"Urothelial carcinomas arising in arsenic-contaminated areas are associated with hypermethylation of the gene promoter of the death-associated protein kinase Abstract: AIMS: The mechanisms of urothelial carcinogenesis in areas highly contaminated with arsenic remain unclear. The aim was to determine whether hypermethylation of death-associated protein kinase (DAPK) gene is associated with chronic arsenic exposure. METHODS AND RESULTS: The frequency of aberrant promoter methylation of DAPK in 17 urothelial carcinomas from an arsenic-contaminated area and 21 urothelial carcinomas from a non-arsenic-contaminated area was determined by methylation-specific polymerase chain reaction. DAPK hypermethylation status was significantly higher in urothelial cancers arising in arsenic-contaminated areas when compared with tumours from patients from non-contaminated areas (P = 0.018). In the subset of patients from living environments which were contaminated with arsenic, there was a statistically significant association between DAPK hypermethylation and patient's age, tumour invasiveness, histological grade and recurrence. This was not seen for urothelial carcinoma from patients from non-contaminated areas. A close correlation was also found between DAPK promoter methylation and low-intensity DAPK expression, as detected by immunohistochemistry (P = 0.037). CONCLUSION: Exposure to arsenic may induce DAPK promoter hypermethylation and inactivate the function of DAPK in urothelial carcinoma. This could prove to be a key molecular event contributing to the malignant phenotype of tumour arising in patients from arsenic-contaminated environments.",
Arsenic,2343549,"Key parameters controlling arsenic dynamics in coastal sediments: An analytical and modeling approach Abstract: The coupling of analytical tools and modeling approaches allowed the identification of the key parameters controlling arsenic (As) dynamics in anoxic marine sediments. Eh, pH, dissolved/particulate As, Fe, Mn, S, P, and organic/inorganic C were determined in sedimentary porewaters and in the sediments itself at 3 geochemically contrasting stations and at different seasons, in the heavily contaminated, semi-closed Toulon bay (NW Mediterranean Sea). Elemental analysis and selective extractions allowed the identification of As distribution in the studied sediments. Organic matter (OM) quality was characterized by fluorescence measurements. AID steady-state modeling (PROFILE) was used to estimate depth reaction intervals and reaction rates by fitting the measured element profiles. Thermodynamic simulation (PHREEQC) was also performed to calculate the chemical speciation and simulate the dissolved/particulate As fractionation. This work demonstrated the consistency of the additive speciation/adsorption modeling to simulate As profiles in marine porewaters while considering the different sedimentary phases and the species that could potentially act as competitors (e.g. CO32-, PO43-, ...). By taking into account the presence of OM and appropriately adjusting its reactivity toward As, the simulated dissolved As profiles consistently fitted the measured one. This As-OM reactivity is related to the organic matter quality, determined by fluorescence measurements. <br> <br>In all samples, As dynamics in the subsurface sediments was shown to be strongly linked to the iron cycling, especially to amorphous iron oxyhydroxide, through diagenesis reactions. The Fe/As ratio involved in the diagenesis processes (determined both experimentally and from the PHREEQC simulation of the dissolved As profiles without organic matter interaction) was close to similar to 210. Higher ratio was predicted by the simulation when considering the As-organic matter interaction. A similar observation was found for other mineral phases in sulfidic sediments (sulfide, clays ...). The decreased affinity of As for inorganic minerals could be due to a competition between organic/inorganic phases or to a ternary arsenic-OM-inorganic phase association, as recently suggested in the literature. Trials provided OM-As stability constant values in these samples, ranging (in log(10)) from 2 to 3.2 for particulate OM and from 2 to 4.7 for dissolved OM. Therefore, organic matter was clearly shown to play a role in As dynamics in sediments or porewater (and thus potentially in other natural samples), even in the presence of inorganic phases. OM, thus, should be added in databases and taken into account in future simulations. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,2088500,"Arsenic incorporation in synthetic struvite (NH4MgPO4•6H2O): A synchrotron XAS and single-crystal EPR study Abstract: Struvite, a common biomineral and increasingly important fertilizer recovered from wastewater treatment plants, is capable of sequestering a wide range of heavy metals and metalloids, including arsenic. Inductively coupled plasma mass spectrometric (ICPMS) analyses and microbeam synchrotron X-ray flurorescence (?-SXRF) mapping show that struvite formed under ambient conditions contains up to 547±15 ppm As and that the uptake of As is controlled by pH. Synchrotron As K-edge XANES spectra measured at 20 K show that As5+ is the predominant oxidation state in struvite, irrespective of Na2HAsO4•7H2O or NaAsO2 as the source for As. Modeling of As K-edge EXAFS data suggest that local structural distortion associated with the substitution of As5+ for P5+ in struvite reaches up to 3.75 Å. Single-crystal electron paramagnetic resonance (EPR) spectra of gamma-ray-irradiated struvite disclose five [AsO3]2- radicals and one [AsO4]2- radical. These arsenic-centered oxyradicals are all readily attributed to form from diamagnetic [AsO4]3- precursors during irradiation, providing further support for exclusive incorporation and local structural expansion beyond the first shell of As5+ at the P site in struvite.",
Arsenic,31014,"Effects of toxic chemicals on the respiratory activity of cultured mouse neuroblastoma cells Abstract: The effects of 20 common toxic chemicals on respiratory activity were investigated in mouse neuroblastoma cells. Cultured cells were grown in medium and maintained at 37 degrees-C in 5.0 percent carbon-dioxide in air. For determination of oxygen consumption, chambers were perfused with a phosphate buffered saline solution. Measurements were made polarographically with oxygen electrodes. Effects of pentachlorophenol (87865) were recorded as an initial increase followed by a gradual dose related decrease in respiration. A corresponding time course of effects was obtained for the high concentrations of hexachlorophene (70304), whereas the low concentrations caused only inhibition. Potassium-cyanide (151508), pyridine (110861), 2,5-hexanedione (110134), meta-arsenite, potassium-chromate (7789006), mercury-chloride (51312244), methylmercury (22967926), and triethyltin (997502) caused an immediate progressive dose dependent decrease in respiration. Simpler time courses of inhibition were obtained with these substances. Ethanol (64175), methanol (67561), dimethyl-sulfoxide (67685), benzidine (71432), nickel-acetate (373024), manganese-chloride (7773015), phenol (108952), cobalt-chloride (1332827), sodium-selenate (13410010), and cadmium-chloride (10108642) produced no significant changes in respiration. The authors conclude that the system presented is useful for determining toxic action of chemicals on neural respiratory activity.",
Arsenic,2345799,"Spatial extraction model for soil environmental quality of anomalous areas in a geographic scale Abstract: An approach to establish a soil environmental assessment model was proposed to evaluate the soil environmental quality level. The kriging technique and a self-organizing map (SOM) were integrated to investigate the soil environmental quality in a geographic information system (GIS). In this study, SOM was applied to categorize the data set of nine heavy metals in topsoil. A total of 261 topsoil samples were collected to determine the concentrations of Cu, Pb, Zn, Cd, Ni, Cr, Hg, As, and Mn. The samples were clustered into three classes by SOM and visualized by GIS. The results show that different environmental quality categories are significantly different and that the soil environmental quality assessment model is effective.",
Arsenic,1017560,"Effects of low-level arsenic exposure on urinary N-acetyl-?-D-glucosaminidase activity Abstract: This study was aimed to evaluate whether renal tubular function is impaired by exposure to relatively low concentrations of arsenic. Mean urinary arsenic concentrations and N-acetyl-?-D-glucosaminidase (NAG) activities were compared among 365 and 502 Korean men and women, respectively, in relation to gender, smoking, alcohol consumption, and recent seafood consumption. The study subjects were divided into 4 groups according to urinary NAG activity and seafood consumption prior to urine sampling, and the correlation between arsenic concentration and urinary NAG activity was tested for each group. The mean urinary arsenic level was higher in women, non-smokers, and non-drinkers in comparison to men, smokers, and drinkers, respectively. Individuals who consumed seafood within 3 days prior to urine sampling showed a higher mean urinary arsenic level than those who did not. The correlation between urinary arsenic concentration and NAG activity in urine was significant only in subjects who did not consume seafood within 3 days prior to urine sampling and whose urinary NAG activity was 7.44 U/g creatinine (75th percentile) or higher. The urinary arsenic concentration was a significant determinant of urinary NAG activity in subjects with NAG activity higher than 7.44 U/g creatinine and especially in those who had not consumed seafood recently. These facts suggest that a relatively low-level exposure to inorganic arsenic produces renal tubular damage in humans.",
Arsenic,744877,"Centrosome Abnormality And Cell Colony Formation (Cell Transformation) In Human Lung Cells Induced By Arsenic Abstract: Epidemiological studies indicated that residents, especially cigarette smokers, in arseniasis areas were significantly higher in lung cancer incidences than those living in the general population. Thus an interaction between arsenic and cigarette smoking in lung cancer development is suspected. p53 mutation in lung epithelial cells is generally accepted as a consequence in cigarette smoking. Our hypothesis was that p53 dysfunction (either via mutation or inhibition) would serve as a platform for arsenic to promote carcinogenesis in human lung epithelial cells. BEAS-2B human lung epithelial cells, with or without pifthrin (Pif, a known p53 inhibitor) treatment (30uM), and human lung adenocarcinoma cell line H1355 were used in our investigation. These cells were treated with different doses of arsenic (0, 1, 5, and 10 uM) for 48 hours. Based on our cell viability study, 5-10 uM was selected as our investigative dose for arsenic exposure. Our study demonstrated that arsenic induced apoptosis and G2/M cell cycle arrest in BEAS-2B cells but not in the H1355 (p53 mutated) or BEAS-2B+Pif (p53 inhibited) cells. Via gamma-tubulin immunostaining technique, we further demonstrated that there were an increased number of cells in the H1355 and BEAS-2B+Pif cell cultures showing centrosome abnormalities (existed in multiple numbers and located in atopic positions) with increasing dose of arsenic. Colony formation (an indication of cell transformation) was also observed in BEAS-2B+Pif cells cultures in soft-agar with arsenic treatment but not in BEAS-2B cells. Our present study demonstrated that p53- compromised (dysfunction) cells were more susceptible to arsenic?s promotion on pre-carcinogenic changes (resistance to apoptosis, centrosome abnormality, and cell transformation). Our present findings also echoed and supported the epidemiological observations that arsenic exposure further increased lung cancer risk in cigarette smokers.",
Arsenic,1248962,"Evaluation of health risk and arsenic levels in vegetables sold in markets of Dhaka (Bangladesh) and Salamanca (Spain) by hydride generation atomic absorption spectroscopy Abstract: The main objective of this study was to determine arsenic (As) levels in vegetables collected from the markets of Dhaka, Bangladesh and for comparison from Salamanca, Spain by HGAAS under optimal conditions, and the potential health risk from consumption of these vegetables. The mean and range of the total As concentration in the vegetables from the markets of Dhaka, Bangladesh were 114 and 1.0-293 ?g/kg, respectively. Total As concentration in 77 % of Bangladesh vegetables measured was higher than that recommended by the standard. The mean and range of As concentrations for vegetables grown in Spain were 65 and bdl-130 ?g/kg, respectively, for Salamanca, 102 and bdl-423 ?g/kg, respectively, for Almeria. The As content of the Bangladesh vegetables was approximately twofold to threefold higher than those observed for the vegetables from Almeria and Salamanca (Spain), but in some cases, were similar or less. Daily consumption of As-rich vegetables may result in an additional source of As in the diet, based on the provisional tolerable intake of As for adults recommended by WHO.",
Arsenic,2298694,"Modern Scientific Evidence Pertaining to Criminal Investigations in the Chosun Dynasty Era (1392-1897 A.C.E.) in Korea Abstract: A guidebook detailing the process of forensic investigation was written in 1440 A.C.E. It outlines the fundamentals and details of each element of criminal investigation during the era of the Chosun dynasty in Korea. Because this old guidebook was written in terms of personal experience rather than on scientific basis, it includes many fallacies from the perspective of modern forensic science. However, the book describes methods to form a scientific basis for the experiments performed. We demonstrate the modern scientific basis for ancient methods to monitor trace amounts of blood and detect lethal arsenic poisoning from a postmortem examination as described in this old forensic guidebook. Traces of blood and arsenic poisoning were detected according to the respective color changes of brownish red, due to the reaction of ferric ions in blood with acetic ions of vinegar, and dark blue, due to the reaction of silver with arsenic sulfide.",
Arsenic,1453815,"Upregulation of microRNA-1 and microRNA-133 contributes to arsenic-induced cardiac electrical remodeling Abstract: BACKGROUND: A large body of evidence showed that arsenic trioxide (As(2)O(3)), a front-line drug for the treatment of acute promyelocytic leukemia, induced abnormal cardiac QT prolongation, which hampers its clinical use. The molecular mechanisms for this cardiotoxicity remained unclear. This study aimed to elucidate whether microRNAs (miRs) participate in As(2)O(3)-induced QT prolongation. METHODS: A guinea pig model of As(2)O(3)-induced QT prolongation was established by intravenous injection with As(2)O(3). Real-time PCR and Western blot were employed to determine the expression alterations of miRs and mRNAs, and their corresponding proteins. RESULTS: The QT interval and QRS complex were significantly prolonged in a dose-dependent fashion after 7-day administration of As(2)O(3). As(2)O(3) induced a significant upregulation of the muscle-specific miR-1 and miR-133, as well as their transactivator serum response factor. As(2)O(3) depressed the protein levels of ether-a-go-go related gene (ERG) and Kir2.1, the K(+) channel subunits responsible for delayed rectifier K(+) current I(Kr) and inward rectifier K(+) current I(K1), respectively. In vivo transfer of miR-133 by direct intramuscular injection prolonged QTc interval and increased mortality rate, along with depression of ERG protein and I(Kr) in guinea pig hearts. Similarly, forced expression of miR-1 widened QTc interval and QRS complex and increased mortality rate, accompanied by downregulation of Kir2.1 protein and I(K1). Application of antisense inhibitors to knockdown miR-1 and miR-133 abolished the cardiac electrical disorders caused by As(2)O(3). CONCLUSIONS: Deregulation of miR-133 and miR-1 underlies As(2)O(3)-induced cardiac electrical disorders and these miRs may serve as potential therapeutic targets for the handling of As(2)O(3) cardiotoxicity.",
Arsenic,1016269,"Overexpression of phytochelatin synthase in Arabidopsis leads to enhanced arsenic tolerance and cadmium hypersensitivity Abstract: Phytochelatin synthase (PCS) catalyzes the final step in the biosynthesis of phytochelatins, which are a family of cysteine-rich thiol-reactive peptides believed to play important roles in processing many thiol-reactive toxicants. A modified Arabidopsis thaliana PCS sequence (AtPCS1) was active in Escherichia coli. When AtPCS1 was overexpressed in Arabidopsis from a strong constitutive Arabidopsis actin regulatory sequence (A2), the A2::AtPCS1 plants were highly resistant to arsenic, accumulating 20-100 times more biomass on 250 and 300 microM arsenate than wild type (WT); however, they were hypersensitive to Cd(II). After exposure to cadmium and arsenic, the overall accumulation of thiol-peptides increased to 10-fold higher levels in the A2::AtPCS1 plants compared with WT, as determined by fluorescent HPLC. Whereas cadmium induced greater increases in traditional PCs (PC2, PC3, PC4), arsenic exposure resulted in the expression of many unknown thiol products. Unexpectedly, after arsenate or cadmium exposure, levels of the dipeptide substrate for PC synthesis, gamma-glutamyl cysteine (gamma-EC), were also dramatically increased. Despite these high thiol-peptide concentrations, there were no significant increases in concentrations of arsenic and cadmium in above-ground tissues in the AtPCS1 plants relative to WT plants. The potential for AtPCS1 overexpression to be useful in strategies for phytoremediating arsenic and to compound the negative effects of cadmium are discussed.",
Arsenic,2337138,"Sodium phosphaethynolate, Na(OCP), as a ""P"" transfer reagent for the synthesis of N-heterocyclic carbene supported P-3 and PAsP radicals Abstract: Sodium phosphaethynolate, Na(OCP), reacts as a P- transfer reagent with the imidazolium salt [(NHC)-N-Dipp-H]-[Cl] [(NHC)-N-Dipp = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] to give the parent phosphinidene-carbene adduct, (NHC)-N-Dipp=PH, with the loss of CO. In a less atom economic reaction, the cage compound, P-7(TMS)(3) (TMS = SiMe3) reacts likewise with the imidazolium salt to yield (NHC)-N-Dipp=PH thereby giving two entry points into parent phosphinidene-based chemistry. From the building block (NHC)-N-Dipp=PH, the carbene-supported P-3 cation [((NHC)-N-Dipp)(2)(mu-P-3)][Cl] was rationally synthesized using half an equivalent of PCl3 in the presence of DABCO (1,4-diazabicyclo[2.2.2] octane). The corresponding arsenic analogue, [((NHC)-N-Dipp)(2)(mu-PAsP)][Cl], was synthesized in the same manner using AsCl3. The reduction of both [((NHC)-N-Dipp)(2)(mu-P-3)][Cl] and [((NHC)-N-Dipp)(2)(m-PAsP)][Cl] into their corresponding neutral radical species was achieved simply by reducing the compounds with an excess of magnesium. This allowed the electronic structures of the compounds to be investigated using a combination of NMR and EPR spectroscopy, X-ray crystallography, and computational studies. The findings of the investigation into ((NHC)-N-Dipp)(2()mu-P-3) and ((NHC)-N-Dipp)(2)(mu-PAsP) reveal the central pnictogen atom in both cases as the main carrier of the spin density (similar to 60%), and that they are best described as the P-3 or PAsP analogues of the elusive allyl radical dianion. The phosphorus radical was also able to undergo a cycloaddition with an activated acetylene, followed by an electron transfer to give the ion pair [((NHC)-N-Dipp)(2)(mu-P-3)][P-3(C(COOMe))(2)].",
Arsenic,1032244,"Determination of total arsenic in environmental samples from Kumasi and Obuasi, Ghana Abstract: The total arsenic content of some Ghana food and cash crops from Kumasi and Obuasi farms and markets was determined. Quantitative analysis of arsenic was also conducted on vegetation, cooked food obtained from some homes, local fish, and meat, as well as some soil and water samples. In all, 266 samples were examined. Values for Kumasi samples ranged from 0.07 to 7.20 mg/kg arsenic, whereas those for Obuasi ranged from 0.12 to 70.50 mg/kg, confirming that arsenic levels for Obuasi are much higher than those for Kumasi.",
Arsenic,1339051,"Effects of choline on sodium arsenite-induced neural tube defects in chick embryos Abstract: Arsenic passes through the placenta and accumulates in the neuroepithelium of embryo, whereby inducing congenital malformations such as neural tube defects (NTDs) in animals. Choline (CHO), a methyl-rich nutrient, functions as a methyl donor to participate in methyl group metabolism. Arsenic methylation has been regarded as a detoxification process and choline (CHO) is the major source of methyl-groups. However, whether CHO intake reverses the abnormal embryo development induced by sodium arsenite (SA) and the relationship between CHO intake and arsenite-induced NTDs are still unclear. In this study, we used chick embryos as animal model to investigate the effects of SA and CHO supplementation on the early development of nervous system. Our results showed that the administration of SA led to reduction in embryo viability, embryo body weight and extraembryonic vascular area, accompanied by a significantly increased incidence of the failed closure of the caudal end of the neural tube. CHO, at low dose (25?g/?L), reversed the decrease in embryo viability and the increase in the failed closure of the caudal end of the neural tube, which were induced by SA. In addition, CHO (25?g/?L) inhibited not only the SA-induced cell apoptosis by up-regulating Bcl-2 level, but also the global DNA methylation by increasing the expressions of DNMT1 and DNMT3a. However, less significant difference was found between the embryos co-treated with SA and CHO (50?g/?L) and the ones treated with SA alone. Taken together, these findings suggest that low dose CHO could protect chick embryos from arsenite-induced NTDs by a possible mechanism related to the methyl metabolism.",
Arsenic,1356878,"Assessment of exposure to arsenic and life style in Korean Abstract: Arsenic(As) is widely distributed in environment and has been known as a human carcinogen. The main source of As in general population is a contaminated food or drinking water. We observed in previous study that seafood consumption increased urinary As metabolites, dimethylarsinic acid(DMA), in volunteers. In this study, we investigated the exposure level of As and life style/diet habit in Korean. We recruited 336 adults (137 males and 199 females) of over 30 years old from 3 districts (urban, rural and coastal areas). The subjects were interviewed for occupation, residence, smoking, drinking, drug, drinking water and past medical history, and were analyzed for diet habit by 24 hour recall method. Blood and urine sampled from subjects. Exposure level to As was evaluated with urinary total and inorganic As metabolites, and some biological indices, such as GSH, GPX, lipid peroxidation and uric acid, were analyzed. Urinary total As was analyzed by hydride generation method, and arsenic speciation was performed by using HPLC with ICP-mass spectrometry. The exposure level of As was age-dependent and affected by seafood consumption, while was negative correlated with animal protein, animal oil and meat consumption. The DMA was major arsenic species in urine. This result suggests that life style/diet habit could be role as one of factors to determine the exposure level to As in general population.",
Arsenic,1519193,"Effect of L-cysteine on drying and neutron irradiation loss of Hg, Se, As, and Br from fish tissue Abstract: Powdered, thawed composited, and fresh frozen fish tissues were analyzed for Hg, Se, As, and Br. Experiments were designed to measure or estimate upper limits of long-term storage, drying, and instrumental neutron activation analysis (INAA) irradiation-related analyte losses. Tissue was analyzed as received (dried, if necessary, for INAA) and treated with l-cysteine to determine if such treatment reduces analyte loss, especially for Hg. Untreated tissues experienced large (23–49%) volatile Hg losses during irradiation. l-Cysteine treatment followed by freeze drying reduced Hg losses to 0.9–3.5%. Desiccation over Mg(ClO4)2 and oven drying at 40 °C of treated tissues were less successful at reducing Hg irradiation loss. Irradiation losses for volatile Se, As, and Br species were smaller, ranging from 0.06–0.4%, <0.01–0.11%, and 0.02–1.0%, respectively. Treated tissue drying losses for Hg, Se, As, and Br ranged from about 3–20%, ?2–6%, <0.2–6%, and <0.3–3%, respectively, depending on drying method. There was some evidence that, unlike for Hg, l-cysteine treatment enhanced Se drying loss. There was little evidence of element loss during long-term storage at ?80 °C, except for an 8% loss from Hg in desiccator dried, l-cysteine treated powdered fish protein.",
Arsenic,86964,"Activation of MAPKs in human bronchial epithelial cells exposed to metals Abstract: U.S. Environmental Protection Agency. #We have previously shown that in vitro exposure to metallic compounds enhances expression of interleukin (IL)-6, IL-8, and tumor necrosis factor-""alpha"" in human bronchial epithelial cells. To characterize signaling pathways involved in metal-induced expression of inflammatory mediators and to identify metals that activate them, we studied the effects of As, Cr, Cu, Fe, Ni, V, and Zn on the mitogen-activated protein kinases (MAPK) extracellular receptor kinase (ERK), c-Jun NH2-terminal kinase (JNK), and P38 in BEAS cells. Noncytotoxic concentrations of As, V, and Zn induced a rapid phosphorylation of MAPK in BEAS cells. Activity assays confirmed marked activation of ERK, JNK, and P38 in BEAS cells exposed to As, V, and Zn. Cr and Cu exposure resulted in a relatively small activation of MAPK, whereas Fe and Ni did not activate MAPK under these conditions. Similarly, the transcription factors c-Jun and ATF-2, substrates of JNK and P38, respectively, were markedly phosphorylated in BEAS cells treated with As, Cr, Cu, V, and Zn. The same acute exposure to As, V, or Zn that activated MAPK was sufficient to induce a subsequent increase in IL-8 protein expression in BEAS cells. These data suggest that MAPK may mediate metal-induced expression of inflammatory proteins in human bronchial epithelial cells.",
Arsenic,657853,"Expression of STAT3 and Bcl-6 oncoprotein in sodium arsenite-treated SV-40 immortalized human uroepithelial cells Abstract: Arsenic is widely distributed in the environment, and it is a proven toxic and carcinogenic agent. On the southwest coast of Taiwan, an endemic occurrence of chronic arsenical poisoning due to a high concentration of arsenic in artesian-well water has been reported. However, the mechanisms of its carcinogenic action are still unclear. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway is an essential cascade for mediating normal functions of different cytokines in the development of the hematopoietic and immune systems. In this study, the substantial morphological changes observed in SV-40 immortalized human uroepithelial cells (SV-HUC-1) after treatment of various concentrations of arsenite were examined, and the expression of Bcl-6, Jak-2 and p-STAT3 (Tyr 705) were evaluated by immunocytochemistry and Western blotting. Our results showed that the expression of Bcl-6 increased dose-dependently in arsenite-treated urothelial cells. Sodium arsenite treatment reduced Jak-2 protein expression in a dose-dependent manner. However, treatment of SV-HUC-1 cells with arsenite at concentration ranges from 2 and 4 ?M for 48 h dramatically increased p-STAT3 (Tyr 705), but the levels decreased at 8–40 ?M of arsenite. Our data suggest that arsenic-mediated inactivation of the JAK-STAT signaling pathway might be caused by Bcl-6 interaction with JAK tyrosine kinase or STAT. In conclusion, our findings indicate that arsenic inhibits JAK tyrosine kinase protein expression and suggest the interference in the JAK-STAT pathway might be through Bcl-6 playing an important role in arsenic-associated carcinogenesis.",
Arsenic,2343525,Screening Samples for Arsenic by Inductively Coupled Plasma-Mass Spectrometry for Treaty Samples Abstract: Final rept. Aug-Oct 2012.,
Arsenic,1342484,"The impact of various contaminants on the trace metal content of compost Abstract: The trace metal content of municipal solid waste (MSW) compost affects the quality and potential end uses of the finished product. The impact of typical contaminants found in the organic fraction of MSW on the trace metal content of compost was investigated. Contaminants including alkaline batteries, galvanized nails, zinc-plated screws, copper wires, and electronic cables were exposed to a thermophilic composting process for three weeks. The increase in trace metal content in the compost product was measured at the end of the composting process. The results showed that low-quality alkaline batteries, galvanized nails, zinc-plated nails, and copper wires had a significant impact on the zinc, copper, arsenic, lead, and cobalt contents of compost. Copper wires showed the highest impact on copper content, which was 52% of the Canadian Council of Ministers of the Environment (CCME) Category A limit in the final compost. Galvanized nails contributed to final levels of zinc reaching 30% of the CCME Category A limit. To ensure that CCME Category A criteria can be achieved, it is recommended that contaminants made from bare copper or coated with zinc be removed from the composting feedstock.",
Arsenic,1020599,"Association of c-myc overexpression and hyperproliferation with arsenite-induced malignant transformation Abstract: Numerous studies link arsenic exposure to human cancers in a variety of tissues, including the liver. However, inorganic arsenic has never been unequivocally shown to be an animal carcinogen, and its carcinogenic mechanism remains undefined. Our previous studies indicate that chronic (&gt; or =18 weeks), low-level (125 to 500 nM) exposure to arsenite induces malignant transformation in the normally nontumorigenic rat liver epithelial cell line (TRL 1215), and these chronic arsenic-exposed (CAsE) cells produce invasive and metastatic tumors upon inoculation into nude mice. In addition, a prior microarray screening analysis of aberrant gene expression showed several oncogenes were overexpressed in CAsE cells exposed to 500 nM arsenite, including a prominent overexpression of the protooncogene c-myc, as well as genes related to cell proliferation. Thus, to better understand the mechanism of arsenic carcinogenesis, we studied the role of c-myc overexpression in arsenite-induced cell transformation. The upregulation of c-myc was confirmed by RT-PCR at the transcription level and by Western blot analysis for the translation product. Further analysis showed that arsenite produced significant increases in the steady-state expression of c-myc in a time- and concentration-dependent manner during the malignant transformation process. The level of c-myc expression was highly correlated (r = 0.988) with tumor formation after inoculation of CAsE cells into nude mice and was also highly correlated (r = 0.997) with genomic DNA hypomethylation. CAsE cells showed a high cell proliferation rate in a fashion related to the level of arsenic exposure. The expression of c-myc was highly correlated with cellular hyperproliferation (r = 0.961). Consistent with the enhanced proliferation both proliferating cell nuclear antigen and cyclin D1 were overexpressed in CAsE cells. In summary, a prominent overexpression of c-myc, a gene frequently activated during hepatocarcinogenesis, is strongly correlated with several events possibly associated with arsenic-induced malignant transformation, including hyperproliferation, DNA hypomethylation and tumor formation upon inoculation into nude mice. These correlations provide convincing evidence c-myc overexpression is mechanistically important in arsenic-induced malignant transformation in this model system.",
Arsenic,1332259,"Genotoxic monitoring of workers at a hazardous waste disposal site in Mexico Abstract: Twelve male volunteers, employed at a hazardous waste dump site, participated in a cytogenetic study to evaluate the genotoxic effects from occupational exposure. After completing a life style and medical questionnaire, each participant provided peripheral blood samples. The frequencies of sister chromatid exchanges (SCE) and cell proliferation kinetics (CPK) were determined in cultured lymphocytes. Chromosomal aberration frequencies for exposed and referent participants were compared. When smoking habits were accounted for, no significant differences in frequency of aberration were observed. No effects were observed regarding SCE or CPK, although the exposed workers exhibited much higher frequencies of chromatid and chromosomal deletions with a high correlation to exposure time. Urine analysis was positive for arsenic (7440382) only. The authors suggest that when high risk exposure is suspected, biomarkers should be used to determine genotoxic damage in risk assessments.",
Arsenic,710809,"Arsenic exacerbates atherosclerotic lesion formation and inflammation in ApoE-/- mice Abstract: Exposure to arsenic-contaminated water has been shown to be associated with cardiovascular disease, especially atherosclerosis. We examined the effect of arsenic exposure on atherosclerotic lesion formation, lesion composition and nature in ApoE-/- mice. Early post-natal exposure (3-week-old mice exposed to 49 ppm arsenic as NaAsO(2) in drinking water for 7 weeks) increased the atherosclerotic lesion formation by 3- to 5-fold in the aortic valve and the aortic arch, without affecting plasma cholesterol. Exposure to arsenic for 13 weeks (3-week-old mice exposed to 1, 4.9 and 49 ppm arsenic as NaAsO(2) in drinking water) increased the lesion formation and macrophage accumulation in a dose-dependent manner. Temporal studies showed that continuous arsenic exposure significantly exacerbated the lesion formation throughout the aortic tree at 16 and 36 weeks of age. Withdrawal of arsenic for 12 weeks after an initial exposure for 21 weeks (to 3-week-old mice) significantly decreased lesion formation as compared with mice continuously exposed to arsenic. Similarly, adult exposure to 49 ppm arsenic for 24 weeks, starting at 12 weeks of age increased lesion formation by 2- to 3.6-fold in the aortic valve, the aortic arch and the abdominal aorta. Lesions of arsenic-exposed mice displayed a 1.8-fold increase in macrophage accumulation whereas smooth muscle cell and T-lymphocyte contents were not changed. Expression of pro-inflammatory chemokine MCP-1 and cytokine IL-6 and markers of oxidative stress, protein-HNE and protein-MDA adducts were markedly increased in lesions of arsenic-exposed mice. Plasma concentrations of MCP-1, IL-6 and MDA were also significantly elevated in arsenic-exposed mice. These data suggest that arsenic exposure increases oxidative stress, inflammation and atherosclerotic lesion formation.",
Arsenic,1508655,"Measured versus modeled dietary arsenic and relation to urinary arsenic excretion and total exposure Abstract: Chronic exposure to arsenic (As) in food and water is a significant public health problem. Person-specific aggregate exposure is difficult to collect and modeling based on limited food As residue databases is of uncertain reliability. Two cross-sectional population exposure studies, the National Human Exposure Assessment Survey-Arizona and Arizona Border Survey, had a combined total of 252 subjects with diet, water, and urinary As data. Total As was measured in 24-h duplicate diet samples and modeled using 24-h diet diaries in conjunction with several published food surveys of As. Two-stage regression was used to assess the effects of dietary As on urinary total As (uAs): (1) generalized linear mixed models of uAs above versus below the limit of detection (LOD); and (2) restricted models limited to those subjects with uAs&gt;LOD, using bootstrap sampling and mixed models adjusted for age, sex, body mass index, ethnicity, current smoking, and As intake from drinking and cooking water. In restricted models, measured and modeled estimates were significant predictors of uAs. Modeled dietary As based on Total Diet Study mean residues greatly underestimated the dietary intake. In households with tap water As ?10?p.p.b., over 93% of total arsenic exposure was attributable to diet.",
Arsenic,1247621,"Environmental mutagens induced transversions but not transitions in regulatory region of mitochondrial DNA Abstract: One of the long-term objectives of the research in our laboratory was to determine whether mitochondrial DNA (mtDNA) mutations were generated in cell lines exposed to a variety of known mutagens. Many of these mutagens are known to increase oxidative stress in the cell, and one potential outcome of this would be an increased incidence of point mutations in mtDNA. Recently, there has been some controversy regarding the validity of point mutations in the regulatory region of mtDNA as a predictive or causative marker for carcinogenesis. Studies were undertaken to assess whether nuclear mutagens such as arsenic (As), asbestos, and ultraviolet (UV) and gamma-radiation, induced both heteroplasmic and homoplasmic point mutations in mtDNA. A direct sequencing approach was used to reduce the occurrence of experimental errors and cross-checked all base changes with databases of known polymorphisms. Our results showed that, while base changes did occur, there was no marked difference between the number of changes in treated and untreated cells. Furthermore, in human lymphocyte samples from subjects exposed to As, most of these base changes were previously reported. Interestingly, there was an increase in the number of transversions (purine ( pyrimidine) in smokers from a human population study, but as with the findings in cell culture samples, there was no difference in the total number of base changes. Data suggest that only a change in the number of rare transversions would be indicative of an increase in point mutations in mtDNA after exposure to mutagens.",
Arsenic,2347692,"Molecular control of arsenite-induced apoptosis in Caenorhabditis elegans: Roles of insulin-like growth factor-1 signaling pathway Abstract: Apoptosis is one of the main cellular processes in responses to arsenic, the well known environmental carcinogen. By using the nematode Caenorhabditis elegans as an in vivo model, we found that insulin-like growth factor-1 networks and their target protein DAF-16/FOXO, known as key regulators of energy metabolism and growth, played important roles in arsenite-induced apoptosis. Inactivation of DAF-2, AGE-1 and AKT-1 caused worms more susceptible to arsenite-induced apoptosis, which could be attenuated by DAF-16 knockout. Worms with inactivated AKT-2 and SGK-1 or with constitutively activated PDK-1 and AKT-1 showed low levels of apoptosis, which could be elevated by DAF-16 mutation. Our results demonstrated that DAF-2/IGF-1R, AGE-1/PI3K, PDK-1/PDK1 and AKT-1/PKB negatively regulated the arsenite-induced apoptosis, whereas AKT-2 and SGK-1 acted proapoptotically. DAF-16/FOXO antagonized IGF-1 signals in signaling the arsenite-induced apoptosis, and apoptosis promoted by DAF-16 inactivation was attributed to its higher sensitivity to oxidative stress.",
Arsenic,628497,"Gene expression alteration during redox-dependent enhancement of arsenic cytotoxicity by emodin in HeLa cells Abstract: Emodin (1,3,8-trihydroxy-6-methylanthraquinone) could enhance the sensitivity of tumor cells to arsenic trioxide (As2O3)-induced apoptosis via generation of ROS, but the molecular mechanism has not been elucidated. Here, we carried out cDNA microarray-based global transcription profiling of HeLa cells in response to As2O3/emodin cotreatment, comparing with As2O3-only treatment. The results showed that the expression of a number of genes was substantially altered at two time points. These genes are involved in different aspects of cell function. In addition to redox regulation and apoptosis, ROS affect genes encoding proteins associated with cell signaling, organelle functions, cell cycle, cytoskeleton, etc. These data suggest that based on the cytotoxicity of As2O3, emodin mobilize every genomic resource through which the As2O3-induced apoptosis is facilitated.",
Arsenic,69316,"Induction of arsenite tolerance and thermotolerance by arsenite occur by different mechanisms Abstract: Both V79 and As/R28A cells (an arsenite-resistant Chinese hamster V79 cell variant) show increased resistance to toxic concentrations of arsenite after pretreatment with a nontoxic concentration. The induced tolerance can be completely inhibited by actinomycin D or cycloheximide. Pretreatment with a nontoxic heat shock (45 degrees C, 10 min) resulted in a clear increased thermotolerance in both cell lines but failed to induce arsenite tolerance in either cell line. Pretreatment with arsenite induced a thermotolerance in V79 cells but not in As/R28A cells. These results are consistent with a model whereby the signal for induction of arsenite tolerance involves binding of arsenite to a protein effector which is amplified in the As/R28A line, thereby preventing action of arsenite in the regulation of heat shock factor which induces the heat shock response.",
Arsenic,2279217,"A6.3 Patients with bronchiectasis, with or without rheumatoid arthritis, have an elevated anti-citrullinated peptide antibodies (ACPA) response Abstract: <strong>BACKGROUND AND OBJECTIVES: </strong>ACPA, particularly antibodies to citrullinated enolase and vimentin, are associated with smoking in patients with rheumatoid arthritis (RA). There is increasing evidence that these links are due to expression of citrullinated proteins in the lungs of smokers. Whether this is a direct effect of smoking or inflammation is presently poorly understood. Bronchiectasis, a strong risk factor for RA, tends to occur in non-smokers, and can therefore be used to examine the role of inflammation in generating an ACPA response independent of smoking.<br /><br /><strong>MATERIALS AND METHODS: </strong>This multi-centre study included 53 patients with HRCT proven bronchiectasis and RA, 50 patients with RA without lung disease, 124 bronchiectasis without RA and 87 asthma patients as controls. Serum samples were analysed for ACPAs using anti-CCP (2(nd) generation assay) and in-house ELISA's were used to measure fine specificities to citrullinated ?-enolase (CEP-1), citrullinated vimentin (cVim) and fibrinogen (cFib) together with their arginine-containing control peptides. Smoking history was detailed for all patients.<br /><br /><strong>RESULTS: </strong>Comparing the RA/bronchiectasis and the RA patients without lung disease, anti-CCP antibodies were more frequently positive (87% vs 48%) and titre significantly greater (p&lt;0.0001) in the RA/bronchiectasis group, despite a lower frequency of smoking (42% vs 58%). The frequency and titre were also increased in the RA/bronchiectasis group for anti CEP-1 (60% vs 24%; p &lt; 0.001), cVim (34% vs 11%; p &lt; 0.001) and anti-cFib (38% vs 18%; p = 012). Comparing the bronchiectasis with asthma groups, none of who had RA, 5% vs 2% had anti-CCP, 9% vs 2% had anti CEP-1 and none were anti-cVim or anti-cFib positive. However, the increased ACPA response in bronchiectasis vs asthma was significant for anti-CEP-1 (p &lt; 0.001). Testing with REP-1, the arginine-containing control peptide for enolase, showed that the response in the bronchiectasis patients was not citrulline-specific.<br /><br /><strong>CONCLUSIONS: </strong>We have demonstrated that despite a low prevalence of smokers, RA/bronchiectasis patients have increased anti-CCP antibodies and an ACPA fine specificity profile similar to that previously shown in RA and smoking (anti-CEP-1 and anti-cVIM). Additionally we identified significantly elevated levels of anti-CEP-1 in the bronchiectatis patients, though unlike in the RA patients, the response was not citrulline-specific, similar to that previously reported for periodontitis. This indicates that the lung may be an initiating site for immunity to RA autoantigens due to inflammation independent of smoking.",
Arsenic,628649,"Transformation by inorganic arsenic compounds of normal Syrian hamster embryo cells into a neoplastic state in which they become anchorage-independent and cause tumors in newborn hamsters Abstract: Arsenic is a known human carcinogen, but little evidence exists for its carcinogenicity in animals. In order to investigate the ability of inorganic arsenics to transform normal cells into a neoplastic state, mass cultures of normal, diploid Syrian hamster embryo (SHE) cells exposed to various concentrations of sodium arsenite or sodium arsenate for 48 hr were continually passaged and tested for neoplastic transformation, as determined by anchorage-independent growth in semisolid agar and tumorigenicity in newborn hamsters. Twenty-one of 22 (96%) untreated, control cultures senesced by 20 passages. While 1 culture escaped senescence, it did not acquire the ability to either grow in semisolid agar or form tumors in animals. Ten of 14 (71%) cultures exposed to sodium arsenite or sodium arsenate escaped senescence. Nine of the 10 (90%) arsenic-treated immortal cultures acquired the anchorage-independent phenotype. Five of 5 anchorage-independent cultures examined were tumorigenic. Two of 3 morphologically transformed colonies induced by sodium arsenate also acquired the ability to grow in semisolid agar when isolated. Amplification of the c-myc or c-Ha-ras oncogene was detected in 3 of 5 and 4 of 5 tumorigenic cell lines, respectively. Both c-myc and c-Ha-ras were amplified even in a preneoplastic, anchorage-dependent cell line, but neither was amplified in 6 of 9 anchorage-independent cell lines. Overexpression of c-myc and c-Ha-ras mRNA was observed in most of the neoplastically transformed cell lines but not in the preneoplastic cell line. Experiments using the methylation-sensitive restriction endonuclease isoschizomers HpaII and MspI revealed hypomethylation of c-myc and c-Ha-ras in the 5-CCGG sequence of arsenic-exposed cell lines but not in the parental SHE cells or a spontaneously transformed cell line. Thus, inorganic arsenics induce neoplastic transformation of normal, diploid mammalian cells. Overexpression of oncogenes by DNA hypomethylation may participate in the arsenic-induced neoplastic transformation of mammalian cells.",
Arsenic,1936213,"Health-risk market garden production linked to heavy metals in irrigation water in Benin Abstract: Heavy metals in the Benin market garden products: is irrigation water the first factor in question, and what is the level of health risk linked to the consumption of these vegetables? Such are the essential problems that this survey attempts to solve. Comparison of the level of lead (Pb), cadmium (Cd) and arsenic (As) pollution shows that all the vegetables taken from three market sites are differently contaminated, as well as their irrigation water and the soil. But establishing that water is the first factor responsible for the presence of heavy metals in market garden products is not so obvious. Otherwise, the health risk assessment revealed that the total daily exposure dose (DED) of Cd, namely 8.05?g/kg/day, is high compared to the daily dose defined by the WHO, which is 1?g/kg/day. Also, the ensuing quotient of danger (QD) is 8.05; such a value poses public health risks for the consumer.",
Arsenic,1378714,DEVELOPMENT OF A PROPOSED INTERNATIONAL STANDARD FOR DETERMINING ARSENIC IN WORKPLACE AIR USING HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE ARSENIC III OXIDE ARSINE ENVIRONMENTAL SURVEILLANCE MAXIMUM EXPOSURE LIMIT PERMISSIBLE EXPOSURE LIMIT PROPOSED DRAFT INTERNATIONAL STANDARD DIS 11041 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION NIOSH OSHA ANALYTICAL METHOD,
Arsenic,2278940,"Mass loads of dissolved and particulate mercury and other trace elements in the Mt. Amiata mining district, Southern Tuscany (Italy) Abstract: Total dissolved and particulate mercury (Hg), arsenic (As), and antimony (Sb) mass loads were estimated in different seasons (March and September 2011 and March 2012) in the Paglia River basin (PRB) (central Italy). The Paglia River drains the Mt. Amiata Hg district, one of the largest Hg-rich regions worldwide. Quantification of Hg, As, and Sb mass loads in this watershed allowed (1) identification of the contamination sources, (2) evaluation of the effects of Hg on the environment, and (3) determination of processes affecting Hg transport. The dominant source of Hg in the Paglia River is runoff from Hg mines in the Mt. Amiata region. The maximum Hg mass load was found to be related to runoff from the inactive Abbadia San Salvatore Mine (ASSM), and up to 30 g day(-1) of Hg, dominantly in the particulate form, was transported both in high and low flow conditions in 2011. In addition, enrichment factors (EFs) calculated for suspended particulate matter (SPM) were similar in different seasons indicating that water discharge controls the quantities of Hg transported in the PRB, and considerable Hg was transported in all seasons studied. Overall, as much as 11 kg of Hg are discharged annually in the PRB and this Hg is transported downstream to the Tiber River, and eventually to the Mediterranean Sea. Similar to Hg, maximum mass loads for As and Sb were found in March 2011, when as much as 190 g day(-1) each of As and Sb were measured from sites downstream from the ASSM. Therefore, the Paglia River represents a significant source of Hg, Sb, and As to the Mediterranean Sea.",
Arsenic,1348335,"Analysis and assessment of trace elements pollution in sediments of Lake Uluabat, Turkey Abstract: ",
Arsenic,1019157,"Neurological effects of environmental exposure to arsenic in dust and soil among humans Abstract: Persons living in a small town in Georgia, USA, were studied because of known environmental exposure to arsenic-containing dust. To assess the effects of this exposure on the nervous system, a cross-sectional epidemiological study was performed. The health outcome assessments of the study were based on a priori selected clinical examination results and quantitative electrophysiologic and behavioral outcome measures. Because the primary goal was to identify cases of peripheral neuropathy, a clinically relevant case definition, based on results of these outcomes was created. Historical exposure reconstructions were performed on a subset of the exposed subjects for whom such information was available. Of the 238 persons enrolled in the study, 133 were classified as non-exposed (i.e., did not reside in the area of known exposure) and 105 were classified as exposed (i.e., did reside in the area of known exposure). Following exclusions of persons with occupational exposure to neurotoxicants, pre-existing conditions associated with peripheral nerve impairment, or age below 18 years, 118 unexposed subjects and 85 exposed subjects were available for inclusion in the analyses of peripheral nerve outcomes. A total of 4 (3.4%) of the unexposed subjects and 13 (15.3%) of the exposed subjects met the case definitions for peripheral neuropathy (OR=5.1; p=0.004). Comparison of three exposure groups (none, low, high) did not yield statistically significant differences. Statistically significant exposure group differences were observed on quantitative tests of standing steadiness, vibrotactile threshold and tremor intensity but not for nerve conduction measures. These results demonstrate a strong association between community arsenic containing dust exposure and peripheral neuropathy among participants in this investigation.",
Arsenic,1029269,"Induction of neoplastic transformation by ectopic expression of human aldo-keto reductase 1C isoforms in NIH3T3 cells Abstract: We have shown previously that chronic low-dose arsenic exposure induces malignant transformation of human skin keratinocyte HaCaT cells. In this study, we found that several isoforms of aldo-keto reductase 1C (AKR1C) were overexpressed in arsenic-exposed HaCaT cells. The AKR1C family of proteins are phase I drug-metabolizing enzymes involved in maintenance of steroid homeostasis, prostaglandin metabolism and metabolic activation of polycyclic aromatic hydrocarbons. To explore the oncogenic potential of AKR1C isoforms, we established mouse NIH3T3 cell lines ectopically and stably expressing human AKR1C1, AKR1C2 or AKR1C3. Our results showed that ectopic expression of human AKR1C1 and AKR1C2, but not AKR1C3, significantly enhanced foci formation. Following subcutaneous injection of these stable cell lines into nude mice, fibrosarcoma were formed from all three cell lines. However, the number and size of tumors formed by the AKR1C3-expressing cell line was fewer and smaller, respectively, than those formed by AKR1C1- and AKR1C2-expressing cells. Inhibitors of AKR1C, genistein and ursodeoxycholic acid, decreased foci formation in AKR1C1- and AKR1C2-expressing NIH3T3 cells in a dose-dependent manner, implying the association of enzymatic activity and oncogenic potential of AKR1C. The requirement of enzymatic ability for neoplastic transformation was confirmed by establishing a NIH3T3 cell line stably expressing a mutant AKR1C1 lacking enzymatic activity, which did not form foci in culture or tumors in nude mice. Our present study reveals that AKR1C enzymatic activity plays crucial roles on induction of neoplastic transformation of mouse NIH3T3 cells.",
Arsenic,1019388,"Signal transduction pathways regulated by arsenate and arsenite Abstract: Arsenate and arsenite activate c-Jun N-terminal kinase (JNK), however, the mechanism by which this occurs is not known. By expressing inhibitory mutant small GTP-binding proteins, p21-activated kinase (PAK) and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinases (MEKKs), we have identified specific proteins that are involved in arsenate- and arsenite-mediated activation of JNK. We observe a distinct difference between arsenate and arsenite signaling, which demonstrates that arsenate and arsenite are capable of activating unique proteins. Both arsenate and arsenite activation of JNK requires Rac and Rho. Neither arsenate nor arsenite signaling was inhibited by a dominant-negative mutant of Cdc42 or Ras. Arsenite stimulation of JNK requires PAK, whereas arsenate-mediated activation of JNK was unaffected by inhibitory mutant PAK. Of the four MEKKs tested, only MEKK3 and MEKK4 are involved in arsenate-mediated activation of JNK. In contrast, arsenite-mediated JNK activation requires MEKK2, MEKK3 and MEKK4. These results better define the mechanisms by which arsenate and arsenite activate JNK and demonstrate differences in the regulation of signal transduction pathways by these inorganic arsenic species.",
Arsenic,1345629,"Gold mining and submarine tailings disposal: Review and case study Abstract: Environmental impacts associated with submarine tailings disposal (STD) of gold mine wastes vary widely among the relatively few cases studied. The principal contaminants of concern surrounding most gold mines are arsenic, mercury, and cyanide, although antimony, thallium, lead, zinc, and copper may also be important in particular mines. The mineralogy and ore processing techniques associated with different kinds of gold deposits may strongly influence the outcome of STD. Native gold and its associated minerals are generally less toxic than sulfide-mineral gold, in which the gold is incorporated into sulfide minerals in conjunction with other trace elements. Sulfide gold tailings placed in seawater may be particularly dangerous where ore processing includes oxidation by roasting or aggressive chemical leaching, which transforms the sulfide minerals into relatively unstable oxides and oxy-hydroxides. The case study of the Newmont Minahasa Raya gold mine in Indonesia highlights some of the dangers of gold mine STD. Local villagers observed fish kills shortly after the beginning of STD operations, and they also noted fine red sediment resembling the tailings smothering corals on reefs adjacent to the tailings disposal site. Tailings from this mine dispersed from the intended STD depth of 82 m up to nearby coral reefs, and dispersal extended up to 3.5 km from the end of pipe. Unstable arsenic phases in the tailings accounted for at least 32% of total arsenic in the mine tailings, and less than 10% of total arsenic in fluvially derived marine sediments. Mercury in the submarine tailings was methylated in approximately the same proportions as mercury from artisanal gold mines using mercury amalgamation and in uncontaminated nearshore marine sediments near a watershed with similar bedrock geology. Methyl mercury derived from tailings was incorporated into the local food chain, probably via benthic invertebrates.",
Arsenic,1508559,"The distribution of arsenic in shallow alluvial groundwater under agricultural land in central Portugal: Insights from multivariate geostatistical modeling Abstract: In this study multivariate and geostatistical methods are jointly applied to model the spatial and temporal distribution of arsenic (As) concentrations in shallow groundwater as a function of physicochemical, hydrogeological and land use parameters, as well as to assess the related uncertainty. The study site is located in the Mondego River alluvial body in Central Portugal, where maize, rice and some vegetable crops dominate. In a first analysis scatter plots are used, followed by the application of principal component analysis to two different data matrices, of 112 and 200 samples, with the aim of detecting associations between As levels and other quantitative parameters. In the following phase explanatory models of As are created through factorial regression based on correspondence analysis, integrating both quantitative and qualitative parameters. Finally, these are combined with indicator-geostatistical techniques to create maps indicating the predicted probability of As concentrations in groundwater exceeding the current global drinking water guideline of 10?g/l. These maps further allow assessing the uncertainty and representativeness of the monitoring network. A clear effect of the redox state on the presence of As is observed, and together with significant correlations with dissolved oxygen, nitrate, sulfate, iron, manganese and alkalinity, points towards the reductive dissolution of Fe (hydr)oxides as the essential mechanism of As release. The association of high As values with rice crop, known to promote reduced environments due to ponding, further corroborates this hypothesis. An additional source of As from fertilizers cannot be excluded, as the correlation with As is higher where rice is associated with vegetables, normally associated with higher fertilization rates. The best explanatory model of As occurrence integrates the parameters season, crop type, well and water depth, nitrate and Eh, though a model without the last two parameters also gives quite satisfactory results.",
Arsenic,1025463,"Reproductive consequences of oral arsenate exposure during pregnancy in a mouse model Abstract: <strong>BACKGROUND: </strong>The second most common of all structural birth defects, neural tube defects (NTDs), affect approximately 2.6/1,000 births worldwide, and 1/1,000 births in the United States. Of the many environmental agents suspected of being teratogenic, arsenic (As) is capable of inducing NTDs in laboratory animals.<br /><br /><strong>METHODS: </strong>We evaluated the teratogenicity of oral exposure on embryonic day (E) 7.5 and E:8.5 to As 4.8, 9.6, or 14.4 mg/kg (as sodium arsenate) in an inbred mouse strain, LM/Bc/Fnn, that does not exhibit spontaneous neural tube malformations. Control and arsenic-treated dams (20 per treatment group) were weighed daily, and evaluated for signs of maternal toxicity. Fetuses were evaluated for soft tissue and skeletal malformations.<br /><br /><strong>RESULTS: </strong>There was no maternal toxicity as evidenced by losses in maternal body weight following As treatment. However, liver weights were lower in all As-treated groups, suggesting hepatotoxicity due to As exposure. The number of litters affected with an NTD (exencephaly) in each treatment group was: 0, 1, 5, and 9 for control, As 4.8, 9.6, or 14.4, respectively, which exhibited a positive linear trend. There was evidence for trends between As dose and the number of litters displaying vertebral (p&lt;0.001) and calvarial (p&lt;0.01) abnormalities, components of the axial skeleton. Mean fetal weight of all As-treated groups was significantly less than in control.<br /><br /><strong>DISCUSSION: </strong>In our model, maternal oral treatment with As induced NTDs. It also significantly increased the frequency of axial skeletal anomalies in the offspring exposed in utero, and reduced mean fetal weight, without evidence of maternal toxicity.",
Arsenic,1508554,"Influences of groundwater extraction on the distribution of dissolved As in shallow aquifers of West Bengal, India Abstract: Here we report temporal changes of As concentrations in shallow groundwater of the Bengal Delta Plain (BDP). Observed fluctuations are primarily induced by seasonally occurring groundwater movement, but can also be connected to anthropogenic groundwater extraction. Between December 2009 and July 2010, pronounced variations in the groundwater hydrochemistry were recorded in groundwater samples of a shallow monitoring well tapping the aquifer in 22-25m depth, where As(tot) concentrations increased within weeks from 100 to 315?gL(-1). These trends are attributed to a vertically shift of the hydrochemically stratified water column at the beginning of the monsoon season. This naturally occurring effect can be additionally superimposed by groundwater extraction, as demonstrated on a local scale by an in situ experiment simulating extensive groundwater withdrawal during the dry post-monsoon season. Results of this experiment suggest that groundwater extraction promoted an enduring change within the distribution of dissolved As in the local aquifer. Presented outcomes contribute to the discussion of anthropogenic pumping influences that endanger the limited and yet arsenic-free groundwater resources of the BDP.",
Arsenic,1033760,"Heat shock alters the composition of heteromeric steroid receptor complexes and enhances receptor activity in vivo Abstract: Under normal cellular conditions, human progesterone receptors (PR), immune-isolated from cytosols of T47D breast cancer cells, associate with two heat shock proteins (hsps), hsp 90 and hsp 70. Receptors activated by hormone binding in vivo and extracted from nuclei with 0.5 M NaCl no longer associate with hsp 90 but retain association with hsp 70. We have examined the effect of heat shock treatment of cells on hsp-receptor interactions and on receptor function. Heat shock resulted in a partial reduction in cellular levels of PR, but receptors that remained were functional for both steroid and DNA binding activities. By steady-state [35S]methionine labeling prior to heat shock treatment, it was determined that heat shock did not affect the composition or maintenance of preexisting cytosolic PR.hsp 90.hsp 70 complexes. By contrast, immune isolation of PR complexes from cells pulse-labeled with [35S]methionine showed that heat shock altered the composition of newly synthesized hsps associated with PR. After heat shock, both the highly inducible form of hsp 70 (72K hsp) and a 100K hsp were bound to cytosol PR, and inducible 72K hsp remained bound with the nuclear-activated PR. Neither of these hsps were associated in detectable amounts with PR under normal cellular conditions. With respect to receptor function, heat shock treatment substantially enhanced the activity of PR in vivo as determined by measuring hormone-dependent PR-mediated transcription of a target reporter gene (MMTV-CAT) that was stably transfected into T47D cells. Heat shock treatment alone, in the absence of hormone, did not stimulate MMTV-CAT expression nor did it affect transcription from a control reporter gene, pSV2-CAT, suggesting that enhanced receptor activity was due to an effect on PR-mediated processes and not to a general effect on transcription. Induction of the heat shock response by a related chemical stress (sodium arsenite) also enhanced PR activity in vivo. Interestingly, sodium arsenite produced both a greater induction of hsp 90 and hsp 70 synthesis and a greater fold enhancement of PR-mediated gene transcription than did heat shock. This suggests that enhancement of PR activity is related not only to induction of hsp synthesis but also to the severity of the stress response. The present results provide an indication that in certain cells there may exist an interrelationship between the activation pathways by which cells respond to stress and to steroid hormones. Possible mechanisms responsible for heat shock effects on PR activity are discussed.",
Arsenic,1356313,"Museums can be hazardous to your health Abstract: A short survey of occupational hazards faced by museum employees in the USA. Particular hazards mentioned include exposure to certain hazardous substances: ethylene oxide, DDT, arsenic, asbestos, nitrogen dioxide and silica.",
Arsenic,1797839,"Urinary metabolic biomarkers link oxidative stress indicators associated with general arsenic exposure to male infertility in a Han Chinese population Abstract: To investigate the hypothesis that general environmental arsenic (As) exposure can impair male fertility, we designed a case-control study examining possible correlations between the concentrations of different As species in urine [controls (n = 151) vs cases (n = 140)], urinary metabolic biomarkers [controls (n = 158) vs cases (n = 135)], and infertility characterized by poor semen quality. Regional participants were recruited sequentially from the affiliated hospitals of Nanjing Medical University. Elevated inorganic arsenate (Asi(V)) exposure was associated with infertility: in comparison with the first quartile, subjects with Asi(V) levels above the median were more likely to exhibit male idiopathic infertility with increasing adjusted odds ratios (AOR) of 4.9 [95% confidence interval (CI), 1.8-13.6] and 13.6 (95% CI, 4.8-38.6) at the third and fourth quartiles (P = 0.000 for trend), respectively. Other As species did not exhibit a significant dose-dependent correlation with infertility risk. Levels of urinary biomarkers correlated with both male infertility and Asi(V) concentrations [controls (n = 145) vs cases (n = 123)]; the latter correlation was independent of disease. These included acylcarnitines, aspartic acid, and hydroxyestrone, which were negatively associated with infertility, and uridine and methylxanthine, which were positively associated. In conclusion, for the first time we show that elevated urinary concentrations of Asi(V) from general As exposure are significantly associated with male infertility, and As species may exert toxicity via oxidative stress and sexual hormone disrupting mechanisms, as indicated by related biomarkers.",
Arsenic,1508520,"Validation of estimates of past exposure to arsenic in drinking water using historical urinary arsenic concentrations Abstract: Consumption of inorganic arsenic in drinking water at high levels has been associated with chronic diseases. Research groups have estimated historic exposure using databases and models of arsenic in drinking water supplies, along with participant residential histories. Urinary arsenic species are an established biomarker of recent exposure; we compare arsenic concentrations in historically collected urine samples with predicted estimates of arsenic exposure. Using a cohort of 462 subjects with at least one urine sample collected from 1984-1992 and an arsenic exposure estimate through drinking water at the time of the urine sample, individual exposure estimates were compared with speciated urine arsenic (UAs) concentrations using correlation and multiple regression analyses. Urine inorganic arsenic (UIAs) concentrations (trivalent arsenic, pentavalent arsenic, monomethylarsonic acid, dimethylarsonic acid) were best predicted by residential water arsenic concentrations (R(2)=0.3688), compared with metrics including water consumption (R(2)=0.2038) or water concentrations at employment locations (R(2)=0.2331). UIAs concentrations showed similar correlation when stratified by whether the arsenic concentration was predicted or measured. Residential water arsenic concentrations, independent of water intake or water concentrations at places of employment, best explain the variability in UIAs concentrations, suggesting historical reconstruction of arsenic exposure that accounts for space-time variability and water concentrations may serve as a proxy for exposure.",
Arsenic,1015839,"Arsenic alters behavioral parameters and brain ectonucleotidases activities in zebrafish (Danio rerio) Abstract: Arsenic (As) exposure has been associated with serious chronic health risk to humans including cancer and neurological disturbances. However, there are limited studies about the mechanisms behind its toxicity. In this study, adult zebrafish were exposed to several concentrations of As (0.05, 5, and 15 mg As/L; Na(2)HAsO(4) as As(V)) during 96h to evaluate the zebrafish locomotor activity, anxiety, and brain extracellular nucleotide hydrolysis. We showed that 5mg/L As is able to promote significant decrease in the locomotor activity as evaluated by the number of line crossings. In addition, animals treated with 5 mg/L As presented an increase in time spent in the lower zone of the tank test, suggesting an anxiogenic effect. Considering that behavioral parameters, such as anxiety and locomotion, might be modulated by the purinergic system, we also evaluated the ectonucleotidase activities in zebrafish brain after a 96-h As exposure. A significant decrease in ATP, ADP, and AMP hydrolysis was observed at 0.05, 5, and 15 mg/L when compared to control group. These findings demonstrated that As might affect behavioral parameters and the ectonucleotidase activities in zebrafish, suggesting this enzyme pathway is a target for neurotoxic effects induced by As.",
Arsenic,1030009,The action of arsenic on Bacillus cereus Abstract: ,
Arsenic,1240150,"Can ants be used as indicators of environmental impacts caused by arsenic? Abstract: We evaluated ants as bioindicators of environmental impacts caused by arsenic residuals in the soil. We tested the hypotheses that the presence of arsenic in the soil affects: (1) estimates of resources and habitat condition for arboreal and epigaeic ants; (2) species richness of arboreal and epigaeic ants and (3) arboreal and epigaeic ant species composition. Ants were sampled at an inactivated raticide factory in Nova Lima, Minas Gerais, Brasil, which used arsenic as one of its main byproducts. The following environmental variables were measured: bioavailable arsenic concentration in the soil, the number and density of tree species, plant cover and leaf litter depth. The species richness of arboreal ants decreased with increased bioavailable arsenic concentration whilst epigaeic ants increased with arsenic. Arboreal ants were positively related to the number of tree species, which in turn were negatively affected by arsenic. We verified which ants are good bioindicators of arsenic. Independent verification of the influence of arsenic on background environmental variables was fundamental in defining responses of ant communities, as well as in identifying the most effective pathways for the recovery of biological communities in degraded areas.",
Arsenic,1797778,"Inhibition of monomethylarsonous acid (MMA(III))-induced cell malignant transformation through restoring dysregulated histone acetylation Abstract: Inorganic arsenic (iAs) and its high toxic metabolite, monomethylarsonous acid (MMA(III)), are able to induce malignant transformation of human cells. Chronic exposure to these chemicals is associated with an increased risk of developing multiple cancers in human. However, the mechanisms contributing to iAs/MMA(III)-induced cell malignant transformation and carcinogenesis are not fully elucidated. We recently showed that iAs/MMA(III) exposure to human cells led to a decreased level of histone acetylation globally, which was associated with an increased sensitivity to arsenic cytotoxicity. In the current study, it demonstrated that prolonged exposure to low-level MMA(III) in human urothelial cells significantly increased the expression and activity of histone deacetylases (HDACs) with an associated reduction of histone acetylation levels both globally and lysine specifically. Administration of the HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA), at 4 weeks after the initial MMA(III) treatment inhibited the MMA(III)-mediated up-regulation of the expression and activities of HDACs, leading to increase histone acetylation and prevention of MMA(III)-induced malignant transformation. These new findings suggest that histone acetylation dysregulation may be a key mechanism in MMA(III)-induced malignant transformation and carcinogenesis, and that HDAC inhibitors could be targeted to prevent or treat iAs-related cancers.",
Arsenic,1024744,"Toxicity of dimethylmonothioarsinic acid toward human epidermoid carcinoma A431 cells Abstract: Chronic ingestion of arsenic-contaminated drinking water induces skin lesions and urinary bladder cancer in humans. It is now recognized that thioarsenicals such as dimethylmonothioarsinic acid (DMMTA (V)) are commonly excreted in the urine of humans and animals and that the production of DMMTA (V) may be a risk factor for the development of the diseases caused by arsenic. The toxicity of DMMTA (V) was compared with that of related nonthiolated arsenicals with respect to cell viability, uptake ability, generation of reactive oxygen species (ROS), and cell cycle progression of human epidermoid carcinoma A431 cells, arsenate (iAs (V)), arsenite (iAs (III)), dimethylarsinic acid (DMA (V)), and dimethylarsinous acid (DMA (III)) being used as reference nonthiolated arsenicals. DMMTA (V) (LC 50 = 10.7 microM) was shown to be much more cytotoxic than iAs (V) (LC 50 = 571 microM) and DMA (V) (LC 50 = 843 microM), and its potency was shown to be close to that of trivalent arsenicals iAs (III) (LC 50 = 5.49 microM) and DMA (III) (LC 50 = 2.16 microM). The greater cytotoxicity of DMMTA (V) was associated with greater cellular uptake and distribution, and the level of intracellular ROS remarkably increased in A431 cells upon exposure to DMMTA (V) compared to that after exposure to other trivalent arsenicals at the respective LC 50. Exposure of DMMTA (V) to cells for 24 h induced cell cycle perturbation. Namely, the percentage of cells residing in S and G2/M phases increased from 10.2 and 15.6% to 46.5 and 20.8%, respectively. These results suggest that although DMMTA (V) is a pentavalent arsenical, it is taken up efficiently by cells and causes various levels of toxicity, in a manner different from that of nonthiolated pentavalent arsenicals, demonstrating that DMMTA (V) is one of the most toxic arsenic metabolites. The high cytotoxicity of DMMTA (V) was explained and/or proposed by (1) efficient uptake by cells followed by (2) its transformation to DMA (V), (3) producing ROS in the redox equilibrium between DMA (V) and DMA (III) in the presence of glutathione.",
Arsenic,1017955,"The repressive effect of NF-kappaB on p53 by mot-2 is involved in human keratinocyte transformation induced by low levels of arsenite Abstract: Inorganic arsenic is a ubiquitous environmental contaminant associated with an increased risk of skin hyperkeratosis and cancer. Although several hypotheses that relate to arsenic-induced carcinogenesis have been suggested, the mechanism of action remains obscure. In the present study, molecular mechanisms underlying the inactivation of p53 function and the genomic instability in malignant transformation of the human keratinocyte cell line, HaCaT, induced by low levels of arsenic were investigated. Our results show that long-term exposure of HaCaT cells to sodium arsenite (1.0 microM) increases their proliferation, causes DNA double-strand breaks, and induce anchorage-independent growth. In arsenite-exposed cells, the levels of phospho-p53, p21, and mdm2 increase at early times after exposure. The levels, however, decrease with longer times. Interaction of the promoter of mot-2 (a p53 inhibitor) with nuclear factor kappaB (NF-kappaB) was established by Southwestern and Western blot assays. Blockage of NF-kappaB prevents the increases of arsenite-induced mot-2 levels, and knockdown of mot-2 facilitates the nuclear translocation of p53, indicating that, in HaCaT cells exposed to arsenite, NF-kappaB inhibits p53 function by mot-2. Moreover, inactivation of NF-kappaB facilitated p53-mediated DNA repair and prevented arsenite-induced malignant transformation. Together, the results suggest that the repressive effect of NF-kappaB on p53 by mot-2 leads to genomic instability, which is involved in arsenite-induced malignant transformation of human keratinocytes.",
Arsenic,2088493,"Design and characterization of hybrid morphology nanoarrays as plasmonic Raman probes for antimicrobial detection Abstract: Advances in nanofabrication have allowed the production of new and more reproducible substrates for the Raman detection of trace antimicrobials in water. The superior substrate uniformity combined with the ability to control surface morphology represents a significant step forward in the design of substrates with improved enhancement factors and trace-detection capabilities. The work presented herein successfully combines electron-beam lithography (EBL) and reactive ion-etching (RIE) protocols for the construction, testing, and validation of plasmonic hybrid morphology nanoarrays for the detection of arsenic antimicrobials in water. The fabricated substrates consist of 2500 ?m(2) Ag-coated silicon dioxide (SiO2)/Si pillar nanoarrays of alternating hexagonal and elliptical features. Control of simple fabrication parameters such as inter-particle spacing (gap) and its orientation relative to the laser polarization vector (parallel or orthogonal) result in over a tenfold improvement in the apparent Raman response under optimized conditions. At a 633 nm excitation frequency, the best substrate performance was observed on parallel-oriented features with a 200 nm gap, with over one order of magnitude increase in the apparent surface-enhanced Raman scattering (SERS) signal relative to standard silver-polydimethylsiloxane (Ag-PDMS) nanocomposites. Monitoring of the characteristic As-C stretching band at 594 cm(-1) allowed the detection of arsenic antimicrobials in water well within the parts per million range. Calculated surface-enhancement factors (SEF) for this substrate, employing 532, 785, and 633 nm excitation wavelengths, was within five, six, and seven orders of magnitude, respectively. The effect of substrate morphology and nanofabrication process on the Raman enhancement factor is presented.",
Arsenic,1017169,"Effect of acute and chronic arsenic exposure on growth, structure and virulence of Aeromonas hydrophila isolated from fish Abstract: Aeromonas hydrophila being a ubiquitous bacterium is prone to arsenic exposure. The present study was designed to determine the role of arsenic on growth and virulence of A. hydrophila. Exposure to arsenic (1 mg L(-1) and 2 mg L(-1)) had no effect on growth but significantly inhibited the hemolytic and cytotoxic potential of exposed bacteria. Transmission electron microscopy revealed loss of membrane integrity and presence of condensed cytoplasm suggestive of acute stress in bacteria exposed to arsenic. Arsenic-adapted bacteria were developed by repeated sub-culturing in presence of arsenic. Arsenic-adaptation led to significant recovery in hemolytic and cytotoxic potential. The arsenic-adapted bacteria exhibited normal membrane integrity, decreased cytoplasmic condensation and possessed scattered polysome like structures in the cytoplasm. A positive correlation was observed between arsenic tolerance and resistance to several antimicrobials. Arsenic-adaptation failed to confer cross-protection to mercury and cadmium stress. SDS-PAGE analysis revealed the expression of two new proteins of approximately 85 kDa and 79 kDa respectively in arsenic-adapted A. hydrophila. Plasmid-curing and transformation studies clearly indicate plasmid has no role on arsenic resistance trait of the bacteria. Our study, for the first time, reports a structure and function relationship of xenobiotics on bacteria.",
Arsenic,1070482,"Heavy metals of the Tibetan top soils : Level, source, spatial distribution, temporal variation and risk assessment Abstract: OBJECTIVE: Due to its high elevation, rare human activities and proximity to south Asia where industries are highly developed, it is required to investigate the fragile environment of the Tibetan Plateau. We are aiming to obtain the concentration level, source, spatial distribution, temporal variation and potential environmental risk of Tibetan soils. METHODS: A total of 128 surf ace soil samples were collected and analyzed f or V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb, and an additional 111 samples were analyzed f or Hg and total organic carbon. Concentration comparisons coupled with multivariate statistics were used to analysis the sources of elements of soils. We also carried out Risk assessment on the soils. RESULTS: Concentrations of Hg, Cr, Ni, Cd and Pb are slightly higher than those of the late 1970s. Concentrations of Cr and Ni are higher than averaged world background values. Tibetan soils present a high natural As concentration level. DISCUSSION: Anthropogenic sources may partly contribute to the elevated Hg, Cd and Pb concentrations. Cr and Ni are mainly originated from soil parent materials. Soil elements in Anduo and Qamdo regions may threaten the health of local people. CONCLUSION: Heavy metal elements of Tibetan Plateau are mainly from the natural source. Arsenic present a high background level. Soil elements in Anduo and Qamdo regions may threaten the health of local people, which should be of concern to scientists and the government.",
Arsenic,2225315,"Microbial sulfate reduction and biogeochemistry of arsenic and chromium oxyanions in anaerobic bioreactors Abstract: A pilot-scale anaerobic bioreactor with high levels of microbial sulfate reduction, known to be capable of removing cationic metals from a metal- and acid-contaminated waste stream, was utilized to determine if the system would be effective in removing metals in the form of oxyanions such as arsenate and chromate. The system removed 90 % to >99 % of the arsenic and between 86 % and 94 % of the chromium from a waste stream containing 5 mg/L of each. Cadmium, copper, iron, lead, and zinc also were removed. An equilibrium geochemistry computer modeling code, MINTEQAK, modified from MINTEQA2, was used for the chemical modeling of processes in the bioreactor. Experimental evidence on the chemical and biological reduction of arsenic and chromium and fluorescent diffraction analysis of precipitates support the following hypotheses: the primary removal process for chromium was the reduction of Cr(VI) to Cr(III) by sulfides, followed by precipitation of chromium hydroxide [Cr(OH)3(s)]; removal of arsenic was by direct microbial enzymatic reduction of As(V) to As(III) followed by precipitation of arsenic sulfides (As2S3 or AsS). Experimental evidence and modeling with MINTEQAK confirmed that 90 % to 95 % of the removal of arsenic and chromium occurred in the first quarter volume of the bioreactor. Additional removal of arsenic and chromium occurred in the remaining volume of the bioreactor. The use of a sulfate reduction-based anaerobic treatment system was effective for metal-laden wastewater with elevated concentrations of arsenic and chromium.",
Arsenic,8613,"Assessment of occupational exposure to inorganic arsenic based on urinary concentrations and speciation of arsenic Abstract: An analytical speciation method, capable of separating inorganic arsenic (As (V), As (III] and its methylated metabolites (MMAA, DMAA) from common, inert, dietary organoarsenicals, was applied to the determination of arsenic in urine from a variety of workers occupationally exposed to inorganic arsenic compounds. Mean urinary arsenic (As (V) + As (III) + MMAA + DMAA) concentrations ranged from 4.4 micrograms/g creatinine for controls to less than 10 micrograms/g for those in the electronics industry, 47.9 micrograms/g for timber treatment workers applying arsenical wood preservatives, 79.4 micrograms/g for a group of glassworkers using arsenic trioxide, and 245 micrograms/g for chemical workers engaged in manufacturing and handling inorganic arsenicals. The maximum recorded concentration was 956 micrograms/g. For the most exposed groups, the ranges in the average urinary arsenic speciation pattern were 1-6% As (V), 11-14% As (III), 14-18% MMAA, and 63-70% DMAA. The highly raised urinary arsenic concentrations for the chemical workers, in particular, and some glassworkers are shown to correspond to possible atmospheric concentrations in the workplace and intakes in excess of, or close to, recommended and statutory limits and those associated with inorganic arsenic related diseases.",
Arsenic,1337723,"Arsenic exposure to dairy cows in Bangladesh Abstract: Food-chain contamination by arsenic (As) is a newly uncovered disaster. Effects of As-contaminated drinking water and paddy straw on the excretion of As through milk, urine, and dung of dairy cows (n = 240) were studied in As-prone areas of Bangladesh. Mean (±SEM) total As (inorganic plus organic) concentration in drinking water, paddy straw [dry weight dw)], cow's urine (specific gravity adjusted to 1.035), dung (dw), and milk (wet weight) were 89.6 ± 6.5 ?g/l, 1,114.4 ± 57.3 ?g/kg, 123.6 ± 7.6 ?g/l, 1,693.0 ± 65.1 ?g/kg, and 26.2 ± 2.8 ?g/l, respectively. Significantly (p &lt; 0.01) greater As was in Boro straw (1,386.9 ± 71.8 ?g/kg) than Aus (702.4 ± 67.1 ?g/kg) and Aman (431.7 ± 28.8 ?g/kg) straw and in straw irrigated with shallow (1,697.3 ± 81.9 ?g/kg) than deep well water (583.6 ± 62.7 ?g/kg) and surface water (511.8 ± 30.0 ?g/kg). Significant (p &lt; 0.01) positive correlations were found between As contents of cow's urine and drinking water (r = 0.92) as well as cow dung and straw (r = 0.82). Concentrations of As in cow urine, dung, and milk were increased with the relative increment of As in drinking water and/or straw. These results provide evidence that dairy cows excrete ingested As mainly through urine and dung; thus, As biotransformation through milk remains low. This low concentration of As in milk may be of concern when humans are exposed to multiple sources of As simultaneously. Moreover, As in cow dung could be an environmental issue in Bangladesh.",
Arsenic,1936178,"Comparison of pre- and post-remediation stream water chemistry in the arsenic-contaminated Baccu Locci mine watershed (Italy): Preliminary data Abstract: Environmental issues related to past mining activities have become the subject of public interest only in the last 20-25 years. Consequently, experience related to the mitigation and control of environmental pollution in mining areas is a recent development. The existing methods of remediation are often partially ineffective, especially when applied without an in-depth geochemical and mineralogical study of the site. This paper reports on preliminary data concerning the effect of remediation actions in an arsenic-contaminated mine watershed (Baccu Locci mine – Italy) a few months from its completion. The persistence of the pre-remediation conditions raises some doubt on the effectiveness of the undertaken remediation actions, even if more time is certainly needed to reach a new environmental steady state. Much remains to be learned about mistakes and successes of mine site remediation, and the monitoring of the Baccu Locci area represents an opportunity to acquire new fundamental knowledge on this issue.",
Arsenic,1519085,"Acute Toxicity of Arsenic under Different Temperatures and Salinity Conditions on the White Shrimp Litopenaeus vannamei Abstract: The aim of this study was to determine acute toxicity in the post larvae of the white shrimp Litopenaeus vannamei after 96 h of exposure to dissolved arsenic under three different temperatures and salinity conditions. Recent reports have shown an increase in the presence of this metalloid in coastal waters, estuaries, and lagoons along the Mexican coast. The white shrimp stands out for its adaptability to temperature and salinity changes and for being the main product for many commercial fisheries; it has the highest volume of oceanic capture and production in Mexican shrimp farms. Lethal concentrations (LC50-96 h) were obtained at nine different combinations (3?×?3 combinations in total) of temperature (20, 25, and 30 °C) and salinity (17, 25, and 33) showing mean LC50-96 h values (±standard error) of 9.13?±?0.76, 9.17?±?0.56, and 6.23?±?0.57 mgAs?L(-1)(at 20 °C and 17, 25, and 33 salinity); 12.29?±?2.09, 8.70?±?0.82, and 8.03?±?0.59 mgAs?L(-1) (at 25 °C and 17, 25, and 33 salinity); and 7.84?±?1.30, 8.49?±?1.40, and 7.54?±?0.51 mgAs?L(-1) (at 30 °C and 17, 25, and 33 salinity), respectively. No significant differences were observed for the optimal temperature and isosmotic point of maintenance (25 °C-S 25) for the species, with respect to the other experimental conditions tested, except for at 20 °C-S 33, which was the most toxic. Toxicity under 20 °C-S 33 conditions was also higher than 25 °C-S 17 and 20 °C (S 17 or 25). The least toxic condition was 25 °C-S 17. All this suggests that the toxic effect of arsenic is not affected by temperature changes; it depends on the osmoregulatory pattern developed by the shrimp, either hyperosmotic at low salinity or hiposmotic at high salinity, as observed at least on the extreme salinity conditions here tested (17 and 33). However, further studies testing salinities near the isosmotic point (between 20 and 30 salinities) are needed to clarify these mechanisms.",
Arsenic,1070320,"Technological options for the removal of arsenic with special reference to South East Asia Abstract: Arsenic contamination in ground water, used for drinking purpose, has been envisaged as a problem of global concern. However, arsenic contamination of ground water in parts of South East Asia is assuming greater proportions and posing a serious threat to the health of millions of people. A variety of treatment technologies based on oxidation, co-precipitation, adsorption, ion exchange and membrane process are available for the removal of arsenic from ground water. However, question remains regarding the efficiency and applicability/appropriateness of the technologies, particularly because of low influent arsenic concentration and differences in source water composition. Some of these methods are quite simple, but the disadvantage associated with them is that they produce large amounts of toxic sludge, which needs further treatment before disposal into the environment. Besides, the system must be economically viable and socially acceptable. In this paper an attempt has been made to review and update the recent advances made in the technological development in arsenic removal technologies to explore the potential of those advances to address the problem of arsenic contamination in South East Asia.",
Arsenic,1345014,"BEHAVIOR OF DISSOLVED ANTIMONY, ARSENIC, AND SELENIUM IN THE ATLANTIC-OCEAN Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM RESEARCH ARTICLE MARINE ORGANISM TOXICITY ATMOSPHERIC DEPOSITION UPWELLING",
Arsenic,2347800,"2-(2-Pyridyl) benzimidazole-based ternary Mn(II) complex as an arsenate selective turn-on fluorescence probe: Ppb level determination and cell imaging studies Abstract: 2-(2-Pyridyl) benzimidazole based ternary Mn(II) complex (MnPBINCO) is established as an arsenate selective turn-on fluorescence probe in HEPES buffered (0.1 M, methanol/water = 0.5/99.5, v/v, pH 7.4) solution for the first time. MnPBINCO can determine the presence of HAsO42- at concentrations as low as 1 x 10(-10) M and efficiently detect intracellular HAsO42- under a fluorescence microscope.",
Arsenic,628774,"Sister chromatid exchange analysis in smelting plant workers exposed to arsenic Abstract: There are many studies documenting the genotoxic effects of environmental exposure to arsenic. Nevertheless, few data are available on the genotoxic risks of occupational arsenic exposure. In the present study, we have evaluated whether or not occupational exposure to arsenic in a copper smelting plant results in a significant increase in the frequency of sister chromatid exchange (SCE). SCE frequencies, proliferation rate index (PRI), and high frequency cells (HFCs) were evaluated in peripheral blood lymphocytes from a group of 105 arsenic-exposed workers from a Chilean smelting plant (exposed group). Similar assays were conducted on a group of 55 workers employed at the same mine but involved in administrative jobs (internal control), and on 48 workers of another mine, with no significant levels of arsenic (external control). Small but significant increases in SCE frequency were observed in the arsenic-exposed workers compared with the external control group (6.28+/-0.09 vs. 5.84+/-0.14 SCE/cell; P<0.01). Also, significantly higher frequencies of HFCs were observed in the exposed group (2.21%+/-0.20%) than in either the external control group (1.20+/-0.23; P=0.002) or the internal control group (1.30+/-0.24; P=0.008). However, there was no relationship between arsenic levels in the urine of the subjects and SCE or HFC frequency. The results of the study indicate that copper smelting results in slightly increased levels of DNA damage. However, our data were not consistent with arsenic exposure being the cause of the increase. Copyright (c) 2006 Wiley-Liss, Inc.",
Arsenic,626969,"Arsenic as an endocrine disruptor: arsenic disrupts retinoic acid receptor-and thyroid hormone receptor-mediated gene regulation and thyroid hormone-mediated amphibian tail metamorphosis Abstract: BACKGROUND: Chronic exposure to excess arsenic in drinking water has been strongly associated with increased risks of multiple cancers, diabetes, heart disease, and reproductive and developmental problems in humans. We previously demonstrated that As, a potent endocrine disruptor at low, environmentally relevant levels, alters steroid signaling at the level of receptor-mediated gene regulation for all five steroid receptors. OBJECTIVES: The goal of this study was to determine whether As can also disrupt gene regulation via the retinoic acid (RA) receptor (RAR) and/or the thyroid hormone (TH) receptor (TR) and whether these effects are similar to previously observed effects on steroid regulation. METHODS AND RESULTS: Human embryonic NT2 or rat pituitary GH3 cells were treated with 0.01-5 microM sodium arsenite for 24 hr, with or without RA or TH, respectively, to examine effects of As on receptor-mediated gene transcription. At low, noncytotoxic doses, As significantly altered RAR-dependent gene transcription of a transfected RAR response element-luciferase construct and the native RA-inducible cytochrome P450 CYP26A gene in NT2 cells. Likewise, low-dose As significantly altered expression of a transfected TR response element-luciferase construct and the endogenous TR-regulated type I deiodinase (DIO1) gene in a similar manner in GH3 cells. An amphibian ex vivo tail metamorphosis assay was used to examine whether endocrine disruption by low-dose As could have specific pathophysiologic consequences, because tail metamorphosis is tightly controlled by TH through TR. TH-dependent tail shrinkage was inhibited in a dose-dependent manner by 0.1- 4.0 microM As. CONCLUSIONS: As had similar effects on RAR- and TR-mediated gene regulation as those previously observed for the steroid receptors, suggesting a common mechanism or action. Arsenic also profoundly affected a TR-dependent developmental process in a model animal system at very low concentrations. Because RAR and TH are critical for both normal human development and adult function and their dysregulation is associated with many disease processes, disruption of these hormone receptor-dependent processes by As is also potentially relevant to human developmental problems and disease risk.",
Arsenic,1030096,"Heat shock induces translocation to the nucleus of the unliganded glucocorticoid receptor Abstract: There have been many reports demonstrating the specific association of several heat shock proteins with unliganded steroid hormone receptors. However, little evidence to date has been proposed to link steroid receptor action with the heat shock response in cells. In this paper, we demonstrate the effect of heat and chemical stress on glucocorticoid receptor subcellular localization in mouse L929 cells and in a stably transfected Chinese hamster ovary cell line (WCL2) which over-expresses the mouse glucocorticoid receptor. When WCL2 cells are exposed to 43 degrees C, there is a time-dependent decrease in glucocorticoid receptor hormone-binding capacity in the cytosolic fraction of these cells that correlates with a decrease in amount of glucocorticoid receptor protein. Analysis of both cytosolic and nuclear fractions for glucocorticoid receptor protein via quantitative Western blotting reveals that the unliganded glucocorticoid receptor of non-shocked L929 and WCL2 cells is localized primarily in the cytosolic fraction, whereas unliganded receptor of heat-shocked cells is found almost exclusively in the nuclear fraction. A similar shift to nuclear localization for unliganded glucocorticoid receptor is noted in L929 and WCL2 cells subjected to chemical shock (sodium arsenite). As treatment of these cells with glucocorticoid hormone also results in glucocorticoid receptor that is tightly bound within the nuclear fraction, it is speculated that heat and chemical stress provide a hormone-independent mechanism by which glucocorticoid receptor is transformed to the high affinity nuclear-binding state characteristic of the hormone-bound, transcriptionally active receptor.",
Arsenic,1797768,"An Externally Accessible Linker Region in the Sodium-Coupled Phosphate Transporter PiT-1 (SLC20A1) is Important for Transport Function Abstract: Background/Aims : Members of the SLC20 cotransporter family (PiT-1, PiT-2) are ubiquitously expressed in mammalian tissue and are thought to perform housekeeping functions for intracellular Pi homeostasis as well as being implicated in vascular calcification and renal Pi reabsorption. The aims of this study were to investigate the topology of a linker region in PiT-1 between the predicted 2(nd) and 3(rd) transmembrane domains and to investigate the functional consequences of cysteine substitutions in this region. Methods : Cysteines were substituted at 18 sites in the Xenopus PiT-1 isoform and the mutants were expressed in Xenopus laevis oocytes. Transport function of the mutants was investigated by (32)P tracer or two electrode voltage clamp before and after thiol modification of the novel Cys. Results : Exposure to the thiol reactive reagent resulted in diminished transport function for 7 mutants. The apparent accessibility of 5 of the mutated sites, estimated from the rate of functional thiol modification, was site-dependent. Cysteine substitution at some sites also altered the apparent affinity for Pi and cation (Na(+)/Li(+)) and substrate (phosphate/arsenate) selectivity, further underscoring the importance of this linker in defining PiT-1 transport characteristics. Conclusions: The external accessibility of a linker in PiT-1 was confirmed and sites were identified that determine substrate selectivity and transport function.",
Arsenic,1337702,"Three-year survey of sulfate-reducing bacteria community structure in Carnoulès acid mine drainage (France), highly contaminated by arsenic Abstract: A 3-year survey on sulfate-reducing bacteria (SRB) was conducted in the waters of the arsenic-rich acid mine drainage (AMD) located at Carnoulès (France) to determine the influence of environmental parameters on their community structure. The source (S5 station) exhibited most extreme conditions with pH lowering to ~1.2; iron, sulfate, and arsenic concentrations reaching 6843, 29 593, and 638 mg L(-1) , respectively. The conditions were less extreme at the downstream stations S1 (pH ~3.7; iron, sulfate, and arsenic concentrations of 1114, 4207, and 167 mg L(-1) , respectively) and COWG (pH ~3.4; iron, sulfate, and arsenic concentrations of 854, 3134, and 110 mg L(-1) , respectively). SRB community structures were characterized by terminal restriction fragment length polymorphism and library analyses based on dsrAB genes. The predominant dsrAB sequences detected were most similar to the family Desulfobulbaceae. Additionally, certain phylotypes could be related to spatio-temporal fluctuations of pH, iron, and arsenic species. For example, Desulfohalobiaceae-related sequences were detected at the most acidic sample (pH 1.4) with high iron and arsenic concentrations (6379 and 524 mg L(-1) , respectively). New dsrAB sequences, with no isolated representatives, were found exclusively in COWG. This study gives new insights on SRB community dynamics in AMD systems.",
Arsenic,1797754,"Experimental and simulation studies of anti-reflection sub-micron conical structures on a GaAs substrate Abstract: In order to reduce surface reflection, anti-reflective (AR) coatings are widely used on the surfaces of solar cells to improve the efficiency of photoelectric conversion. This study employed colloidal lithography with a dry etching process to fabricate sub-micron anti-reflection structures on a GaAs substrate. Etching parameters, such as RF power and etching gas were investigated to determine their influence on surface morphology. We fabricated an array of conical structures 550 nm in diameter and 450 nm in height. The average reflectance of a bare GaAs wafer was reduced from 35.0% to 2.3% across a spectral range of 300 nm - 1200 nm. The anti-reflective performance of SWSs was also calculated using Rigorous Coupled Wave Analysis (RCWA) method. Both simulation and experiment results demonstrate a high degree of similarity.",
Arsenic,1247788,"Gene expression changes in human lung cells exposed to arsenic, chromium, nickel or vanadium indicate the first steps in cancer Abstract: The complex process of carcinogenesis begins with transformation of a single cell to favor aberrant traits such as loss of contact inhibition and unregulated proliferation - features found in every cancer. Despite cancer's widespread prevalence, the early events that initiate cancer remain elusive, and without knowledge of these events cancer prevention is difficult. Here we show that exposure to As, Cr, Ni, or vanadium (V) promotes changes in gene expression that occur in conjunction with aberrant growth. We exposed immortalized human bronchial epithelial cells to one of four metals/metalloid for four to eight weeks and selected transformed clonal populations based upon anchorage independent growth of single cells in soft agar. We detected a metal-specific footprint of cancer-related gene expression that was consistent across multiple transformed clones. These gene expression changes persisted in the absence of the progenitor metal for numerous cell divisions. Our results show that even a brief exposure to a carcinogenic metal may cause many changes in gene expression in the exposed cells, and that from these many changes, the specific change(s) that each metal causes that initiate cancer likely arise.",
Arsenic,1508725,"Comparing the utility of a novel neonatal resuscitation cart with a generic code cart using simulation: A randomised, controlled, crossover trial Abstract: <strong>OBJECTIVE: </strong>To compare a novel neonatal resuscitation cart (NRC) to a generic code cart (GCC).<br /><br /><strong>STUDY DESIGN: </strong>A prospective, randomised, controlled, crossover trial was performed to compare the utility of the NRC with the GCC during simulated deliveries of extremely low birthweight infants and infants with gastroschisis. Fifteen subjects participated. Mean times and accuracy of equipment and supply retrieval were compared for each scenario using the Wilcoxon test.<br /><br /><strong>RESULTS: </strong>Mean acquisition times for the NRC were always faster (by 58% to 74%) regardless of scenario (p&lt;0.01). Accuracy of equipment selection did not differ. Ease of use was judged using a Likert scale (1=easiest to use; 5=most difficult), with mean score for NRC 1.1 and GCC 3.7 (p&lt;0.0001). All subjects rated the NRC as easier to use.<br /><br /><strong>CONCLUSIONS: </strong>The NRC was superior to the GCC in acquisition speed, supply selection and ease of use.",
Arsenic,627520,"Arsenic methylation capability and hypertension risk in subjects living in arseniasis-hyperendemic areas in southwestern Taiwan Abstract: BACKGROUND: Cumulative arsenic exposure (CAE) from drinking water has been shown to be associated with hypertension in a dose-response pattern. This study further explored the association between arsenic methylation capability and hypertension risk among residents of arseniasis-hyperendemic areas in Taiwan considering the effect of CAE and other potential confounders. METHOD: There were 871 subjects (488 women and 383 men) and among them 372 were diagnosed as having hypertension based on a positive history or measured systolic blood pressure >or=140 mm Hg and/or diastolic blood pressure >or=90 mm Hg. Urinary arsenic species were determined by high-performance liquid chromatography-hydride generator and atomic absorption spectrometry. Primary arsenic methylation index [PMI, defined as monomethylarsonic acid (MMA(V)) divided by (As(III)+As(V))] and secondary arsenic methylation index (SMI, defined as dimethylarsinic acid divided by MMA(V)) were used as indicators for arsenic methylation capability. RESULTS: The level of urinary arsenic was still significantly correlated with cumulative arsenic exposure (CAE) calculated from a questionnaire interview (p=0.02) even after the residents stopped drinking the artesian well water for 2-3 decades. Hypertensive subjects had higher percentages of MMA(V) and lower SMI than subjects without hypertension. However, subjects having CAE >0 mg/L-year had higher hypertension risk than those who had CAE=0 mg/L-year disregard a high or low methylation index. CONCLUSION: Inefficient arsenic methylation ability may be related with hypertension risk.",
Arsenic,627158,"Zinc-induced arsenite tolerance in mice Abstract: The mechanism of tolerance to arsenic toxicity is not known. Recently it has been shown that arsenic induces metallothionein (MT), which is a sulfhydryl-rich, metal-binding protein that decreases the toxicity of a number of metals. The present studies were designed to examine the role of MT in arsenic toxicity. Zinc (Zn) pretreatment (1000 mumol/kg, sc) markedly increased hepatic MT (150-fold over controls), and also protected against the lethal effects of arsenite (130 mumol/kg, sc). However, no correlation was found between the ability of various known MT inducers (Zn, Cd, arsenite, monomethylarsenite, alpha-hederin, or oleanolic acid) to increase hepatic MT and to protect against arsenic lethality in mice. To examine the mechanism of Zn protection against arsenic toxicity, the subcellular distribution of arsenite in liver, kidney, and small intestine was determined 2 hr after arsenite injection. Zn pretreatment did not markedly alter the amount of arsenic-73 in the cytosol or the various cellular organelles (nuclei, mitochondria, microsomes) in liver kidney, or small intestine. There was also very little arsenic-73 bound to MT in the cytosol of the Zn-pretreated mice, as determined by G-75 gel-filtration chromatography. In mice pretreated with Zn (1000 mumol/kg, sc) and subsequently injected with arsenite-73 (115 mumol/kg, sc), the arsenic-73 content in blood, heart, lung, kidneys, spleen, muscle, and skin was lower than in controls, indicating increased arsenic elimination in Zn-pretreated mice. In conclusion, Zn pretreatment protects mice against arsenite toxicity, but the mechanism of tolerance does not appear to be induction of MT.",
Arsenic,1248942,"Influence of age on arsenic-induced oxidative stress in rat Abstract: Influence of age on arsenic-induced (0.05, 0.1, and 0.2 lethal dose to 50 % population (LD(50)) given intraperitoneally) oxidative stress was investigated in young, adult, and old rats at days 7 and 14 post-exposure. A significant dose-dependent effect of arsenic on biochemical variables suggestive of oxidative stress was noted at day 7 following exposure in old rats. The parameters which were significantly altered include an increased reactive oxygen species, thiobarbituric acid reactive substances (TBARS), catalase activity accompanied by a decreased glutathione level. At day 14 following arsenic exposure (0.05 and 0.1 LD(50) dose), we observed a significant oxidative injury as evident from significant depletion of superoxide dismutase (SOD) and catalase activities in blood and tissues in addition to more pronounced accumulation of arsenic in blood and tissues. Interestingly, the toxicity was pronounced in young and old rats compared with adult rats. Accumulation of arsenic found to be more prominent in old rats compared with young and adult, which might be due to impaired metabolism with ageing. We conclude that young and old animals are more vulnerable to the arsenic-induced oxidative injury which is comparable with arsenic accumulation in blood and tissues and duration of exposure.",
Arsenic,8244,"Test of environmental exposure to arsenic and hearing changes in exposed children Abstract: Arsenic determination was carried out on hair, urine, and blood samples taken from groups of 10-year-old boys, each numbering 20 to 25 individuals, residing in a region polluted by arsenic. In all the examined materials considerably elevated concentrations of arsenic were found. The relation of the observed levels of arsenic to the distance of the place of residence up to a distance of more than 30 km from the source of the emissions was studied. On the basis of the results obtained, the most advantageous material for estimation of nonoccupational exposure to arsenic seems to be hair, in spite of some problems with the decontamination procedure involved. Considerable variability among individual arsenic values in the hair makes group examination a necessity. Hearing changes were analyzed in a group of 56 10-year old children residing near a power plant burning local coal of high arsenic content. The results of both audiometric and clinical examination were compared with those of control group numbering 51 children of the same age living outside the polluted area. The highly standardized audiometric and clinical examination were completed with a questionnaire analysis concerning the personal medical histories of the children. The obtained data were elaborated statistically by means of the chi(2)- test. In the case of air conduction, important hearing losses were found at frequencies of 125, 250 and 8000 Hz, especially at the lowest frequency range. Significant degrees of hearing loss were found in bone conduction as well as in the corresponding ranges of frequencies. The high statistical significance of the hearing impairments found points to very low probability of their being only an &quot;accidental&quot; finding. The possibility of toxic damage to the ear cannot yet be excluded.",
Arsenic,1936198,"PHYTOTOXICITY AND BIOACCUMULATION OF ARSENIC IN CROPS (Sinapis alba L., Triticum aestivum L., Hordeum vulgare L.) Abstract: ",
Arsenic,1020081,"Effects of heat shock protein 70 (Hsp70) on arsenite-induced genotoxicity Abstract: Arsenic, a human carcinogen, is genotoxic, although its mechanism(s) of action for tumorigenesis is not well understood. Among the toxicity-related properties of this chemical are its clastogenic and aneugenic activities, as well as its capacity for inducing stress-response in the form of elevated heat shock protein (HSP) expression. In the present study, we evaluated the effects of Hsp70 expression on arsenite (As)-induced structural and numerical chromosome anomalies in human cells. Human MCF-7 Tet-off cells stably transfected with a pTRE/Hsp70-1 transgene construct were used to regulate Hsp70 levels prior to in vitro As exposures. Separate cultures of relatively high vs. low Hsp70-expressing cells were established. A cytokinesis block micronucleus assay with kinetochore immunostaining was used to detect micronuclei (MN) derived from chromosome breakage (K-MN) or loss (K+MN). These studies demonstrated significant increases in micronucleus frequencies in response to As following either a long exposure (5 or 10 microM for 46 hr), or short exposure (10 or 40 microM for 8 hr) protocol. Overall, the long protocol was more efficient in producing K+MN and cells with multiple MN. Overexpressing Hsp70 resulted in significant reductions in the percent of cells positive for MN for both the long and short As exposure protocols. Both K+ and K- types of As-induced MN were lower in cells with elevated Hsp70 as compared to cells without overexpression of Hsp70. We conclude that the dose and duration of As exposure influence the type as well as amount of chromosomal alteration produced and that inducible Hsp70 protects against both the clastogenic and aneugenic effects of this chemical.",
Arsenic,1597352,"Genome sequence of hydrothermal arsenic-respiring bacterium Marinobacter santoriniensis NKSG1T Abstract: Marinobacter santoriniensis NKSG1(T) originates from metalliferous marine sediment. It can respire and redox cycle arsenic species and perform mixotrophic, nitrate-dependent Fe(II) oxidation. The genome sequence, reported here, will help further elucidate the genetic mechanisms underlying these and other potential biogeochemically relevant functions, such as arsenic and mercury resistance and hydrocarbon degradation.",
Arsenic,1579275,"Effects of vitreomacular adhesion on anti-vascular endothelial growth factor treatment for polypoidal choroidal vasculopathy Abstract: PURPOSE:: To evaluate the effect of posterior vitreomacular adhesion (VMA), documented by optical coherence tomography, on the outcome of anti-vascular endothelial growth factor treatment of polypoidal choroidal vasculopathy. METHODS:: Medical records of 102 patients (104 eyes) with polypoidal choroidal vasculopathy were retrospectively reviewed and categorized according to the presence of posterior VMA into 2 subgroups: VMA positive (+) group (23 eyes) and VMA negative (-) group (81 eyes). Best-corrected visual acuity and central macular thickness after antivascular endothelial growth factor treatment were compared between the 2 groups at baseline and at 1 month, 3 months, 6 months, and 12 months. RESULTS:: At the last follow-up, average number of injections was 4.82 ± 1.27 in the VMA (+) group and 4.92 ± 1.45 in the VMA (-) group. After injection, the mean logarithm of the minimum angle of resolution of best-corrected visual acuity improved from 0.81 ± 0.53 (Snellen equivalent, 20/129) to 0.67 ± 0.52 (Snellen equivalent, 20/93) in the VMA (+) group (P = 0.01) and from 0.79 ± 0.50 (Snellen equivalent, 20/123) to 0.64 ± 0.58 (Snellen equivalent, 20/91) in the VMA (-) group (P = 0.02). Average central macular thickness decreased from 354.4 ± 124.5 ?m to 249.6 ± 112.5 ?m in the VMA (+) group (P = 0.01) and from 361.2 ± 140.2 ?m to 267.3 ± 103.5 ?m in the VMA (-) group (P = 0.01). Polyp regression rate was 21.7% (5 eyes of 23 eyes) in the VMA (+) group and 22.2% (18 eyes of 81 eyes) in the VMA (-) group. There was no statistically significant difference in the best-corrected visual acuity improvement, central macular thickness improvement, and polyp regression rate between the groups. CONCLUSION:: Unlike typical age-related macular degeneration, posterior VMA was not associated with a visual outcome after intravitreal antivascular endothelial growth factor for polypoidal choroidal vasculopathy.",
Arsenic,627092,"Interferon-? Plays protective roles in sodium arsenite-induced renal injury by up-regulating intrarenal multidrug resistance-associated protein 1 expression Abstract: Subcutaneous injection of sodium arsenite (NaAs, 12.5 mg/kg) into BALB/c [wild-type (WT)] mice causes acute renal dysfunction characterized by severe hemorrhages, acute tubular necrosis, and cast formation, with increases in serum blood urea nitrogen and creatinine levels. Concomitant enhancement in intrarenal interferon (IFN)-gamma expression prompted us to examine its roles in this pathology. IFN-gamma-deficient (IFN-gamma-/-) mice exhibited higher serum blood urea nitrogen and creatinine levels and exaggerated histopathological changes, compared with WT mice. Eventually, IFN-gamma-/- mice exhibited a high mortality (87.5%) within 24 hours after NaAs challenge, whereas most WT mice survived. The intrarenal arsenic concentration was significantly higher in IFN-gamma-/- mice later than 10 hours after NaAs treatment, with attenuated intrarenal expression of multidrug resistance-associated protein (MRP) 1, a main transporter for NaAs efflux, compared with WT mice. NF-E2-related factor (Nrf) 2 protein, a transcription factor crucial for MRP1 gene expression, was similarly increased in the kidneys of both strains of mice after NaAs treatment. In contrast, the absence of IFN-gamma augmented transforming growth factor-beta-Smad3 signal pathway and eventually enhanced the expression of activating transcription factor 3, which is presumed to repress Nrf2-mediated MRP1 gene expression. Thus, IFN-gamma can protect against NaAs-induced acute renal injury, probably by maintaining Nrf2-mediated intrarenal MRP1 gene expression.",
Arsenic,1346391,"Effects of fertigation with purified urban wastewater on soil and pepper plant (Capsicum annuum L.) production, fruit quality and pollutant contents Abstract: The effects, in greenhouse conditions, of Purified Urban Wastewater (PW) from Almería (Spain), in the fertigation of pepper (Capsicum annuum L.) on sandy mulch soil, were evaluated. Primary, secondary (active sludges) and tertiary (Chlorination + ozonation) purification treatments were applied to wastewater. Irrigation treatments applied were PW, natural Ground Water (GW), Fertilizer PW (FPW) and Fertilizer GW (FGW). The vegetal biomass, yield and fruit quality were controlled. Heavy metals (Cr, Cd, Pb, Ni, Mn, Cu and Zn), arsenic (As) and Polycyclic Aromatic Hydrocarbons (PAH) in water, soil, leaf, and fruit were analysed. The PW presented heavy metal, As and PAH contents acceptable for its use in drip irrigation. In the soil, fertigated with PW, the concentration of heavy metals and As did not increase, whilst the PAH concentration decreased. The PW treatment supplied enough nutrients to obtain yield and fruit quality equal to that of GW with fertilization. A significant saving on N, P and K fertilizers (37%, 66% and 12% respectively) was achieved by using PW. The Cd, Pb and As contents of the fruit did not show risk for human consumption. The total PAH concentrations in the fruit were low, the highest of which was phenathrene, with no carcinogenic signification.",
Arsenic,1358219,"Vinyl Chloride Exposure in a Controlled Industrial Environment Abstract: The mortality experience of 594 production employees who worked from 1942 to 1960 in areas with potential vinyl-chloride (75014) (VC) exposure was assessed. Industrial hygiene data was reviewed and workers were assigned to one of three exposure groups (based on exposure experience for 1 more months): low, with a time weighted average (TWA) concentration for an 8 hour day below 25 parts per million (ppm) VC; intermediate, with a TWA of 25 to 200ppm VC; and high, with a TWA of over 200ppm VC. Seventy two individuals were exposed to both arsenicals and VC. Data was also obtained by interview, and review of county, state, and Social Security Administration records. Based on the total cohort, a total of 89 deaths were found as compared with the expected rate of 100.1. When those workers exposed to arsenic (7440382) were removed from consideration, an observed mortality rate of 79 was found as compared with the expected rate of 89.1. Deaths due to malignancies were higher than expected in the total cohort population (20 observed deaths compared to 17.9 expected) but were lower when arsenic exposed workers were excluded (13 observed compared to 16.0 expected). Nine of the 13 malignancies observed were in the high exposure group. Seven of the nine individuals in the high exposure group had worked more than 10 years in exposure areas; the remaining two had worked for 5 and 9 years. Among the 13 subjects who were not exposed to arsenic and who died of cancer, 4 had a family history of cancer and 5 smoked more than a half pack of cigarettes daily. The authors suggest that exposure to VC may increase susceptibility to malignant neoplasms among individuals who are at risk due to other factors.",
Arsenic,2088318,"Trace elements and their behaviour during the combustion of marine oil shale from Changliang Mountain, northern Tibet, China Abstract: The Shengli River–Changshe Mountain oil shale zone represents a potentially large marine oil shale resource in China. With the aim of better understanding the geochemistry of trace elements in marine oil shale and its combustion residues, 40 raw samples, 27 oil shale combustion residues and 29 selected minerals from Changliang Mountain oil shale are studied for geochemical analyses. The contents of Se, Cd, Mo, As, Cs, Pb, Sr and U in the oil shale samples are enriched from 1.47 to 33.91 times as compared with the Clarke values, whereas the concentrations of other elements are slightly higher/lower than the respective worldwide means. The most enriched elements in oil shale combustion residues are Se, Cd, Mo, As and U with enrichment values from 4.78 to 50.92. Trace elements with high volatile behaviour such as As, Co, Ni, Sc, Sn and V occur predominantly in organic matter and/or sulphides. Other non-volatile or slightly volatile trace elements (e.g., Be, Bi, Cs, Cu, Ga, Hf, Li, Nb, Rb, Ta, Th, W, Zr and REEs) may occur mainly in original and relatively refractory minerals in raw oil shale. The potentially hazardous trace elements in Changliang Mountain oil shale include As, Cd, Mo and Se. Arsenic and Se are controlled mainly by Fe-bearing minerals (probably pyrite) in Changliang Mountain oil shale. Cadmium is present mainly in dolomite, while Mo occurs mainly in organic matter.",
Arsenic,1015728,"Environmental Risk Presented by Arsenic Contamination of Building and Facility Surfaces in a Coking Plant Abstract: Arsenic contamination on the surface of buildings and facilities at a coking plant and associated health risk were studied. A total of 94 wipe samples from 56 buildings and facilities were collected, and As concentrations were found to range from 0.01 to 23.90 ?g/100 cm(2). 20.2% of the samples exceeded the As level calculated to present health risk: 4.02 ?g/100 cm(2). Arsenic mean concentration was found to be highest on the surface of bricks, and coking zone showing the highest As risk. The findings of this study may provide clues to As pollution control and risk evaluation in coking plants.",
Arsenic,1016348,"Protective role of Moringa oleifera (Sajina) seed on arsenic-induced hepatocellular degeneration in female albino rats Abstract: In an attempt to develop new herbal therapy, an aqueous extract of the seed of Moringa oleifera was used to screen the effect on arsenic-induced hepatic toxicity in female rat of Wistar strain. Subchronic exposure to sodium arsenite (0.4 ppm/100 g body weight/day via drinking water for a period of 24 days) significantly increased activities of hepatic and lipid function markers such as alanine transaminase, aspartate transaminase, cholesterol, triglycerides, LDL along with a decrease in total protein and HDL. A notable distortion of hepatocellular histoarchitecture was prominent with a concomitant increase in DNA fragmentation following arsenic exposure. A marked elevation of lipid peroxidation in hepatic tissue was also evident from the hepatic accumulation of malondialdehyde and conjugated dienes along with suppressed activities in the antioxidant enzymes such as superoxide dismutase and catalase. However, co-administration of aqueous seed extract of M. oleifera (500 mg/100 g body weight/day for a period of 24 days) was found to significantly prevent the arsenic-induced alteration of hepatic function markers and lipid profile. Moreover, the degeneration of histoarchitecture of liver found in arsenic-treated rats was protected along with partial but definite prevention against DNA fragmentation induction. Similarly, generation of reactive oxygen species and free radicals were found to be significantly less along with restored activities of antioxidant enzymes in M. oleifera co-administered group with comparison to arsenic alone treatment group. The present investigation offers strong evidence for the hepato-protective and antioxidative efficiencies of M. oleifera seed extract against oxidative stress induced by arsenic.",
Arsenic,1021633,"Reduced expression of MAPK/ERK genes in perinatal arsenic-exposed offspring induced by glucocorticoid receptor deficits Abstract: Changes within the glucocorticoid receptor (GR) cellular signaling pathway were evaluated in adolescent mice exposed to 50 ppb arsenic during gestation. Previously, we reported increased basal plasma corticosterone levels, decreased hippocampal GR levels and deficits in learning and memory performance in perinatal arsenic-exposed mice. The biosynthesis of members of the mitogen-activated protein kinase (MAPK) signaling pathway, known to be involved in learning and memory, is modulated by the binding of GR to glucocorticoid response elements (GREs) in the gene promoters. Two genes of the MAPK pathway, Ras and Raf, contain GREs which are activated upon binding of GRs. We evaluated the activity of GRs at Ras and Raf promoters using chromatin immunoprecipitation and real-time PCR and report decreased binding of the GR at these promoters. An ELISA-based GR binding assay was used to explore whether this decreased binding was restricted to in vivo promoters and revealed no differences in binding of native GR to synthetic GREs. The decreased in vivo GR binding coincides with significantly decreased mRNA levels and slight reductions of protein of both H-Ras and Raf-1 in perinatally arsenic-exposed mice. Nuclear activated extracellular-signal regulated kinase (ERK), a downstream target of Ras and Raf, whose transcriptional targets also play an important role in learning and memory, was decreased in the hippocampus of arsenic-exposed animals when compared to controls. GR-mediated transcriptional deficits in the MAPK/ERK pathway could be an underlying cause of previously reported learning deficits and provide the link to arsenic-induced deficiencies in cognitive development.",
Arsenic,1019320,"Sodium arsenite-induced dysregulation of proteins involved in proliferative signaling Abstract: It is well accepted that arsenic is a human carcinogen, yet its mechanism of action is not defined. Arsenic cannot be classified as an initiating agent or as a promoter, although altered proliferative responsiveness has been proposed as a mechanism by which arsenic exerts its carcinogenic effects. Based on the hypothesis that arsenic exposure results in modulation of both positive and negative regulators of cell proliferation, this study examined physiological and biochemical changes in the proliferative response of murine fibroblasts grown long-term in the maximum tolerated concentration of sodium arsenite. In response to EGF stimulation, DNA synthesis and the proportion of cells entering S phase of the cell cycle both were increased in cells grown long-term in arsenic compared to control cells. Analysis of positive proliferative regulators revealed an increase in the expression of c-myc and E2F-1, thereby supporting the hypothesis that arsenic increases activity of positive growth modulators. In contrast, the activity and expression of ERK-2 were unchanged, as was the expression of EGF-receptor and mSOS. When negative regulators of proliferation were examined, expression levels of MAP kinase phosphatase-1 and p27(Kip1) were found to be lower in arsenic-treated cells compared to control cells; this result supports a model in which arsenic disinhibits normal regulation of cell proliferation. Taken together, these data indicate that long-term exposure to sodium arsenite creates conditions within the cell consistent with sensitization to mitogenic stimulation. It is further postulated that the observed changes in mitogenic signaling proteins contribute to the carcinogenic property of arsenic.",
Arsenic,628574,"Distinct gene expression profiles in immortalized human urothelial cells exposed to inorganic arsenite and its methylated trivalent metabolites Abstract: Inorganic arsenic is an environmental carcinogen. The generation of toxic trivalent methylated metabolites complicates the study of arsenic-mediated carcinogenesis. This study systematically evaluated the effect of chronic treatment with sodium arsenite (iAsIII), monomethylarsonous acid (MMAIII), and dimethylarsinous acid (DMAIII) on immortalized human uroepithelial cells (SV-HUC-1 cells) using cDNA microarray. After exposure for 25 passages to iAsIII (0.5 ?M), MMAIII (0.05, 0.1, or 0.2 ?M), or DMAIII (0.2 or 0.5 ?M), significant compound-specific morphologic changes were observed. A set of 114 genes (5.7% of the examined genes) was differentially expressed in one or more sets of arsenical-treated cells compared with untreated controls. Expression analysis showed that exposure of cells to DMAIII resulted in a gene profile different from that in cells exposed to iAsIII or MMAIII, and that the iAsIII-induced gene profile was closest to that in the tumorigenic HUC-1–derived 3-methylcholanthrene–induced tumorigenic cell line MC-SV-HUC T2, which was derived from SV-HUC-1 cells by methylcholanthrene treatment. Of the genes affected by all three arsenicals, only one, that coding for interleukin-1 receptor, type II, showed enhanced expression, a finding confirmed by the reduced increase in NF-?B (nuclear factor kappa B) activity seen in response to interleukin-1? in iAsIII-exposed cells. The expression of 11 genes was suppressed by all three arsenicals. 5-Aza-deoxycytidine partially restored the transcription of several suppressed genes, showing that epigenetic DNA methylation was probably involved in arsenical-induced gene repression. Our data demonstrate that chronic exposure to iAsIII, MMAIII, or DMAIII has different epigenetic effects on urothelial cells and represses NF-?B activity.",
Arsenic,1597370,"Measurement of Inorganic Arsenic Species in Rice after Nitric Acid Extraction by HPLC-ICPMS: Verification Using XANES Abstract: The measurement of As species in rice is normally accomplished by extraction followed by HPLC-ICPMS analysis. This method, however, has not been comprehensively validated by comparing these speciation results with XANES, which does not require sample extraction, due to the challenge of conducting XANES analysis at very low As concentrations. In this study As speciation data using nitric acid extraction/HPLC-ICPMS and XANES are compared to verify the efficacy of using 2% v/v nitric acid extraction and HPLC-ICPMS to measure inorganic As, DMA, and MA in reference rice materials and common rice varieties obtainable in Australia. Total As and As species (As(III), As(V), DMA, and MA) concentrations measured in 8 reference materials were in agreement with published values. XANES analysis was performed on 5 samples having total As concentrations ranging from 0.198 to 0.335 ?g g(-1). XANES results gave similar proportions of total As(III), As(V), and DMA to HPLC-ICPMS. XANES was able to distinguish two forms of As(III): As(III) and As(III)GSH. Total As concentrations in rice samples varied from 0.006 to 0.45 ?g g(-1) As (n = 47) with a mean ± std of 0.127 ± 0.112 ?g g(-1) As with most As present as inorganic species (63 ± 26%). DMA was found in nearly all the rice samples with the majority of samples containing concentrations below 0.05 ?g g(-1) As while MA concentrations were negligible (&lt;0.003 ?g g(-1) As). Six rice varieties produced in Australia, China, and Spain all had elevated DMA concentrations (0.170-0.399 ?g g(-1) As) that were correlated with total As concentrations (r(2) = 0.7518). In conclusion, comparison of As speciation by HPLC-ICPMS and XANES showed that similar As species were detected indicating the appropriateness of using 2% v/v nitric acid for extraction of rice prior to speciation. Common rice varieties obtainable in Australia generally have low As concentrations with most As present as inorganic As.",
Arsenic,737184,"Arsenic induced changes in growth development and apoptosis in neonatal and adult brain cells in vivo and in tissue culture Abstract: Arsenic at a nonlethal level in drinking water consumed over a period of time has been reported to produce chronic toxicity and various types of health problems ranging from skin cancer to disturbance in memory. Neurotoxic effects have been reported in clinical cases with chronic exposure to arsenic. Physiological detoxication of arsenic occurs partially through methylation. Arsenic and its methylated derivatives are distributed in different organs and systems. The present study examined the possible interference in the neuronal development and differentiation due to the exposure to arsenic during gestation. The experiments were carried out to examine short and long term effects of arsenic on brain explants and cells grown and maintained in tissue culture system. The effects of arsenic exposure showed changes in brain cell membrane function indicated by generation and release of reactive oxygen-nitrogen intermediates. On the morphological aspect the explants' growth was reduced, ground matrix was lost and neural networking was inhibited. Cells showed signs of apoptotic changes. Arsenic toxicity may induce damage to brain cells prior to more visible clinical conditions. The deleterious effects also pass from the maternal to fetal tissue across the transplacental barrier.",
Arsenic,627433,"Cytotoxic effects of S-(dimethylarsino)-glutathione: A putative intermediate metabolite of inorganic arsenicals Abstract: Glutathione (GSH) plays an important role in the metabolism of arsenite and arsenate by generating arsenic-glutathione complexes. Although dimethylarsinic acid (DMA(V)) is the major metabolite of inorganic arsenicals (iAs) in urine, it is not clear how DMA(V) is produced from iAs. In the present study we report that S-(dimethylarsino)-glutathione (DMA(III)(SG)), a putative precursor of dimethylarsinic acid DMA(V), was unstable in the culture medium without excess GSH and generated volatile substances which were highly cytotoxic for both rat heart microvascular endothelial cells and HL60, a human leukemia cell line. Cytotoxicity of DMA(III)(SG) was higher than that of iAs and its LC(50) value was calculated to be 7.8 microM in the endothelial cells. To our surprise DMA(III)(SG) effectively killed cells in the neighbor wells of the same multi-well dish, indicating that volatile toxic compounds generated from DMA(III)(SG) in the culture medium. High performance lipid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) analyses suggested that the freshly generated volatile compounds dissolved into aqueous solution and formed an unstable arsenic compound and the unstable compound was further converted to DMA(V). These results suggested that DMA(III)(SG) exerts its cytotoxicity by generating volatile arsenicals and is implicated in the metabolic conversion of inorganic arsenicals into DMA(V), a major final metabolite of inorganic arsenicals in most mammals.",
Arsenic,1252586,"Involvement of preferential formation of apurinic/apyrimidinic sites in dimethylarsenic-induced DNA strand breaks and DNA-protein crosslinks in cultured alveolar epithelial cells Abstract: We previously found that lung-specific DNA damage induced by administration of dimethylarsinic acid (DMAA), a main metabolite of inorganic arsenics in mammals, in mice might be due to dimethylarsenic peroxyl radical [(CH3)2AsOO.] produced in the further metabolic processing of DMAA. Further analysis of DNA damage was performed in the present study using a human embryonic cell line of alveolar epithelial (L-132) cells. Alkali-labile sites in DNA were produced prior to DNA single-strand breaks (SSB) and DNA-protein crosslinks (PC) in L-132 cells by exposure to 10mM DMAA. An experiment using methoxyamine (MA), an agent reacting with the aldehyde group of apurinic/apyrimidinic (AP) sites in DNA, indicated that, of the alkali-labile sites formed by exposure to DMAA, major ones were AP sites. These findings suggest that SSB and PC induced by exposure of L-132 cells to DMAA occurred via the formation of AP sites in DNA. That is, SSB were produced by a beta-elimination reaction on AP sites in the DNA and PC by a Schiff-base reaction between amino groups of nuclear proteins and aldehyde groups of AP sites.",
Arsenic,628685,"Elevated mortality from lung cancer associated with arsenic exposure for a limited duration Abstract: In 1959, arsenic poisoning was detected in the town of Nakajo in Japan. The cause was exposure to inorganic arsenic in well water during 1954 to 1959. To examine the long-term effects of limited-duration arsenic exposure, we conducted mortality and survival studies for patients with chronic arsenic exposure and for control subjects from 1959 to 1992. The ratio of observed deaths to expected deaths from lung cancer was significantly high (7:0.64) for male patients. The lung cancer mortality rate was elevated markedly in subgroups with higher clinical severities of symptoms. Small cell carcinoma was specific to the exposed patients. The cumulative change of survival declined significantly in the exposed patients compared with the controls. The decline disappeared when lung cancer deaths were treated as lost to follow-up. The results showed that a 5-year period of arsenic exposure was associated with risk of lung cancer.",
Arsenic,1597431,"Biosolid impact on heavy metal accumulation and lability in soiln under alternate-year no-till corn-soybean rotation Abstract: Biosolids are nutrient-rich waste products often used as soil amendments. To evaluate the impact of repeated application of biosolids on heavy metal accumulation and lability, composite soils (at 0–15- and 15–30-cm depths) were collected from 0-, 2-, 5-, and 25-year biosolid-applied Genesee silt loam (fine loamy, mixed, nonacid, mesic Typic Udifluvent). While the biosolid application did not influence the pH, the electrical conductivity and heavy metal concentration varied significantly. Among the heavy metals, the concentration of total and residual cadmium (Cd) was the highest (3 and 2.8 times), and copper (Cu) was the lowest (1.3 to 1.2 times) in the 25-year biosolid-applied field than in the control. The exchangeable chromium (Cr) concentration was the highest (6 times), and Cu was the lowest (1.9 times) in the 25-year biosolid-applied field as compared with the control. The lability of Cr, lead (Pb), cobalt (Co), zinc (Zn), Cu, nickel (Ni), and arsenic (As) significantly increased by 20, 11, 9, 9, 8, 6, and 4 %, respectively, in the 25-year biosolid-applied field compared to the control field. The extractable Pb, As, Zn, and Cu concentrations were significantly higher at 0–15 cm than at 15–30 cm depth. The labilities of Pb, Cu, and Ni were significantly varied between depths. Biosolids × depth significantly influenced the total As and residual As, Cu, and Pb concentrations. All the heavy metals except total and residual As significantly correlated with the total organic carbon. Results suggest that the accumulation and lability of heavy metals are related to complexation of heavy metals with organic carbon in response to years of biosolid application.",
Arsenic,1337323,"Vaccine specific immune response to an inactivated oral cholera vaccine and EPI vaccines in a high and low arsenic area in Bangladeshi children Abstract: BACKGROUND: Immune responses to the inactivated oral whole cell cholera toxin B (CTB) subunit cholera vaccine, Dukoral(®), as well as three childhood vaccines in the national immunization system were compared in children living in high and low arsenic contaminated areas in Bangladesh. In addition, serum complement factors C3 and C4 levels were evaluated among children in the two areas. VACCINATIONS: Toddlers (2-5 years) were orally immunized with two doses of Dukoral 14 days apart. Study participants had also received diphtheria, tetanus and measles vaccines according to the Expanded Program on Immunization (EPI) in Bangladesh. RESULTS: The mean level of arsenic in the urine specimens in the children of the high arsenic area (HAA, Shahrasti, Chandpur) was 291.8?g/L while the level was 6.60?g/L in the low arsenic area (LAA, Mirpur, Dhaka). Cholera specific vibriocidal antibody responses were significantly increased in the HAA (87%, P&lt;0.001) and the LAA (75%, P&lt;0.001) children after vaccination with Dukoral, but no differences were found between the two groups. Levels of CTB specific IgA and IgG antibodies were comparable between the two groups, whereas LPS specific IgA and IgG were higher in the LAA group, although response rates were comparable. Diphtheria and tetanus vaccine specific IgG responses were significantly higher in the HAA compared to the LAA group (P&lt;0.001, P=0.048 respectively), whereas there were no differences in the measles specific IgG responses between the groups. Complement C3 and C4 levels in sera were higher in participants from the HAA than the LAA groups (P&lt;0.001, P=0.049 respectively). CONCLUSIONS: The study demonstrates that the oral cholera vaccine as well as the EPI vaccines studied are immunogenic in children in high and low arsenic areas in Bangladesh. The results are encouraging for the potential use of cholera vaccines as well as the EPI vaccines in arsenic endemic areas.",
Arsenic,1337271,"Microbial interactions in the arsenic cycle: adoptive strategies and applications in environmental management Abstract: Arsenic (As) is a nonessential element that is often present in plants and in other organisms. However, it is one of the most hazardous of toxic elements globally. In many parts of the world, arsenic contamination in groundwater is a serious and continuing threat to human health. Microbes play an important role in regulating the environmental fate of arsenic. Different microbial processes influence the biogeochemical cycling of arsenic in ways that affect the accumulation of different arsenic species in various ecosystem compartments. For example, in soil, there are bacteria that methylate arsenite to trimethylarsine gas, thereby releasing arsenic to the atmosphere.In marine ecosystems, microbes exist that can convert inorganic arsenicals to organic arsenicals (e.g., di- and tri-methylated arsenic derivatives, arsenocholine,arsenobetaine, arsenosugars, arsenolipids). The organo arsenicals are further metabolized to complete the arsenic cycle.Microbes have developed various strategies that enable them to tolerate arsenic and to survive in arsenic-rich environments. Such strategies include As exclusion from cells by establishing permeability barrier, intra- and extracellular sequestration,active efflux pumps, enzymatic reduction, and reduction in the sensitivity of cellular targets. These strategies are used either singly or in combination. In bacteria,the genes for arsenic resistance/detoxification are encoded by the arsenic resistance operons (ars operon).In this review, we have addressed and emphasized the impact of different microbial processes (e.g., arsenite oxidation, cytoplasmic arsenate reduction, respiratory arsenate reduction, arsenite methylation) on the arsenic cycle. Microbes are the only life forms reported to exist in heavy arsenic-contaminated environments. Therefore,an understanding of the strategies adopted by microbes to cope with arsenic stress is important in managing such arsenic-contaminated sites. Further future insights into the different microbial genes/proteins that are involved in arsenic resistance may also be useful for developing arsenic resistant crop plants.",
Arsenic,2278996,"A clinical review of maternal bacteremia Abstract: <strong>OBJECTIVE: </strong>To carry out a 4-year review of cases of bacteremia among obstetric patients.<br /><br /><strong>METHODS: </strong>In a retrospective review, all cases of maternal bacteremia between 2009 and 2012 were identified from the laboratory database of Coombe Women and Infants University Hospital, Dublin, Ireland. The clinical records of each case were assessed.<br /><br /><strong>RESULTS: </strong>During the study period, 37,584 obstetric patients attended the hospital. There were 58 cases of bacteremia: 19 were diagnosed prepartum, 20 intrapartum, and 19 postpartum. There were no maternal deaths. Two cases resulted in septic shock. Four cases were associated with early pregnancy loss, and 2 with stillbirth. Fifty-four cases occurred among 34,956 women who delivered a neonate weighing 500 g or more (0.15%). Escherichia coli most frequently caused prepartum and postpartum bacteremia, whereas Streptococcus agalactiae (?-hemolytic, Lancefield group B) most frequently caused intrapartum bacteremia. There was no association between the development of bacteremia and maternal risk factors including employment status, obesity, parity, smoking status, and maternal age. Most organisms cultured were sensitive to first-line antibiotics; there were no cases of bacteremia caused by multi-drug resistant organisms.<br /><br /><strong>CONCLUSION: </strong>The incidence of maternal bacteremia in the study population was low and was usually associated with good maternal and fetal outcomes.",
Arsenic,1339154,"Trace elements in faeces of great tit nestlings in relation to breeding performance in coastal areas in central Portugal Abstract: This long-term study (2003-2010) compared the breeding parameters of great tits living in a paper-and-pulp-industry area to those of great tits living in a rural area on the west coast of Portugal. We also measured the abundance of caterpillar biomass, an important food source and determinant of breeding success for tits. In 2009, we further analysed trace metal [arsenic (As), calcium (Ca), cadmium, copper, mercury (Hg), nickel, lead, selenium, and zinc] as well as Ca concentrations in excrement of 15-day-old great tit nestlings. Generally, for most trace metals, fecal concentrations were similar at both sites. Nonetheless, greater Hg levels and lower As levels were detected in the industrial area. Great tits laid more eggs and produced more fledglings in the industrial area than in the rural area. Caterpillar biomass was also greater in the industrial area, which likely explains the better breeding success. Our results suggest that there are no direct effects of emissions on the studied species.",
Arsenic,626993,"Basal metabolism of intraperitoneally injected carrier-free 74As-labeled arsenate in rabbits Abstract: The time-dependent occurrence of [74As]arsenate metabolites in Flemish Giant rabbits was investigated. As absorbed rapidly, reaching maximal concentrations in plasma and packed cells after 30 min and 2 hr, respectively. The [74As]arsenate in plasma and packed cells was reduced to [74As]arsenite, to 35 and 50% of the total 74As, respectively. The concentration of methylated As species in plasma and packed cells increased rapidly after 30 min. About 18% of total plasma 74As maximally bound to transferrin. Two-thirds of total 74As in packed cells bound to hemoglobin. Whereas little or no [74As]monomethylarsonic acid, one of the main As metabolites in humans, could be found in other animals, it is present in measurable amounts in the Flemish Giant. Furthermore, the plasma clearance rate of 74As species is lower than that in other rabbits and more similar to that of humans. The tissue 74As distribution varied widely with the highest concentrations in kidneys, liver, and lungs. 74As accumulated in bone whereas other tissues and blood showed rapid clearance rates. In muscle and heart an important part of arsenic was associated with components insoluble in phosphate-buffered isotonic saline. Binding of arsenic to soluble tissue proteins was most important in the kidneys, liver, and spleen. [74As]Arsenate metabolites were detected in all tissues. The relative amounts of [74As]arsenite or [74As]monomethylarsonic acid seldom exceeded 15% of total tissue 74As. The proportion of [74As]dimethylarsenic acid in the low molecular 74As fraction increased steadily. Substantial amounts of [74As]monomethylarsonic acid were found in the tissues.",
Arsenic,1240314,"Trace metal concentrations in the tropical sponge Spheciospongia vagabunda at a sewage outfall: synchrotron X-ray imaging reveals the micron-scale distribution of accumulated metals Abstract: Major and trace elements were measured in sponges, seawater and sediment in Darwin Harbour (Australia) to test the hypothesis that metals are elevated in sponges closer to a sewage outfall compared with unimpacted sites. Seawater and sediment at the sewage discharge site contained high, but localised, concentrations of phosphorus (P), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As) and lead (Pb) compared with background sites. Metal concentrations in the sponge Spheciospongia vagabunda were highly elevated compared with other sponges and, although site specific, high metal concentrations were unrelated to the presence of sewage effluent. X-ray fluorescence microprobe imaging was used to investigate the metal distribution pattern in S. vagabunda. High Fe, Ni and Zn concentrations were either localised in circular patches (100-200 mu m size) near water canals or in the pinacoderm, or scattered in spots (approximately 10 mu m) throughout the tissue. This supports a microflora-mediated metal bioaccumulation hypothesis. In contrast, Co and Mn were highly dispersed and probably associated with aluminium- and iron-oxide rich sediment inclusions. Although the lack of association between sewage effluent and metal accumulation precludes the use of S. vagabunda as a biomonitor, the apparent differential mechanisms of metal accumulation warrants further investigation.",
Arsenic,1017913,"Changes in hair arsenic concentration in a population exposed to heavy pollution: Follow-up investigation in Chenzhou City, Hunan Province, Southern China Abstract: Follow-up investigation on hair arsenic concentration was conducted in an arsenic heavily polluted area of southern China in 2002 and 2006. The results showed that the geometric mean of hair arsenic concentration decreased from 2.95 mg/kg in 2002 to 1.78 mg/kg in 2006, when the percentage of the population with levels over 1 mg/kg only decreased from 93.4% in 2002 to 80.5% in 2006. Over this four-year period, the population with high arsenic concentrations decreased significantly while there was no obvious change in hair arsenic concentration for people who had relatively low concentrations. In terms of age distribution, young and old people had higher hair arsenic concentrations than the middle-aged. All of these results showed that it is difficult to reverse the negative impact of arsenic pollution on human health. Arsenic pollution has a long-term continuous influence on the health of local residents.",
Arsenic,1016122,"Multielemental analysis of Migori (Southwest, Kenya) artisanal gold mine ores and sediments by EDX-ray fluorescence technique: implications of occupational exposure and environmental impact Abstract: The results of heavy element profiling of the gold ores and sediments associated with the artisanal gold mining activities of the Migori gold belt of Southwestern Nyanza, Kenya, were reported in this paper. The analysis was made to assess the occupational exposure of the miners as well as to investigate the environmental impact of toxic heavy metals. Gold ores and sediments from the artisanal gold processing were sampled in four artisanal gold mining areas: Osiri A, Osiri B, Mikei and Macalder (Makalda) and analyzed for heavy elemental content using (109)Cd radioisotope excited EDXRF spectrometry technique. Analysis consisted of direct irradiating of sample pellets. The concentrations of major elements detected were: titanium (711.41-10,766.67 mg/kg); cobalt (82.65-1,010.00 mg/kg); zinc (29.90-63,210 mg/kg); arsenic (29.30-8,246.59 mg/kg); gold (14.07-73.48 mg/kg); lead (16.31-14,999.40 mg/kg) and mercury (16.10-149.93 mg/kg). The average concentration of the heavy toxic metals i.e. arsenic, lead, titanium and zinc were found to be above 50 mg/Kg as recommended by World Health Organization.",
Arsenic,1020038,"Effectiveness and reliability of arsenic field testing kits: are the million dollar screening projects effective or not? Abstract: The exposure of millions to arsenic contaminated water from hand tube wells is a major concern in many Asiatic countries. Field kits are currently used to classify tube wells as delivering arsenic below 50 microg/L (the recommended limit in developing countries) as safe, painted green or above 50 microg/L, unsafe and painted red. More than 1.3 million tube wells in Bangladesh alone have been tested by field kits. A few million U.S. dollars have already been spent and millions are waiting for the ongoing projects. However, the reliability of the data generated through field kits is now being questioned. Samples from 290 wells were tested by field kits and by a reliable laboratory technique to ascertain the reliability of field kits. False negatives were as high as 68% and false positives up to 35%. A statistical analysis of data from 240 and 394 other wells yielded similar rates. We then analyzed 2866 samples from previously labeled wells and found 44.9% mislabeling in the lower range (&lt;50 microg/L) although mislabeling was considerably reduced in the higher range. Variation of analytical results due to analysts and replicates were pointed out adopting analysis of variance (ANOVA) technique. Millions of dollars are being spent without scientific validation of the field kit method. Facts and figures demand improved, environmentally friendly laboratory techniques to produce reliable data.",
Arsenic,1339691,"Stability of a Pseudomonas putida KT2440 bacteriophage-carried genomic island and its impact on rhizosphere fitness Abstract: The stability of seven genomic islands of Pseudomonas putida KT2440 with predicted potential for mobilization was studied in bacterial populations associated with the rhizosphere of corn plants by multiplex PCR. DNA rearrangements were detected for only one of them (GI28), which was lost at high frequency. This genomic island of 39.4 kb, with 53 open reading frames, shows the characteristic organization of genes belonging to tailed phages. We present evidence indicating that it corresponds to the lysogenic state of a functional bacteriophage that we have designated Pspu28. Integrated and rarely excised forms of Pspu28 coexist in KT2440 populations. Pspu28 is self-transmissible, and an excisionase is essential for its removal from the bacterial chromosome. The excised Pspu28 forms a circular element that can integrate into the chromosome at a specific location, att sites containing a 17-bp direct repeat sequence. Excision/insertion of Pspu28 alters the promoter sequence and changes the expression level of PP_1531, which encodes a predicted arsenate reductase. Finally, we show that the presence of Pspu28 in the lysogenic state has a negative effect on bacterial fitness in the rhizosphere under conditions of intraspecific competition, thus explaining why clones having lost this mobile element are recovered from that environment.",
Arsenic,2347562,"Arsenic toxicity in rice with special reference to speciation in Indian grain and its implication on human health Abstract: <strong>BACKGROUND: </strong>Rice is a potentially important route of human exposure to arsenic, especially in populations with rice-based diets. However, arsenic toxicity varies greatly with species. The initial purpose of the present study was to evaluate arsenic speciation in rice.<br /><br /><strong>RESULTS: </strong>It appeared very clear from the present study that inorganic arsenic shared maximum arsenic load in rice straw while in grains it is considerably low. As species recovered from rice grain and straw are principally As-III and As-V with a little share of DMA and almost non-detectable MMA and As-B. Discussion of the health risk of As in rice has largely been based on its inorganic arsenic content because these species have generally been considered to be more toxic than MMA and DMA and can be directly compared to As in drinking water, assuming equal bioavailability of inorganic As in the rice matrix and in water. The maximum dietary risk of exposure to inorganic arsenic through transplanted boro paddy in the present experiment was calculated to be almost 1706 % of PTWI (Provisional Tolerable Weekly Intake) for an adult of 60 kg bodyweight.<br /><br /><strong>CONCLUSION: </strong>As species recovered from boro rice grain and straw are principally As-III and As-V with a little share of DMA and almost non-detectable MMA and As-B. Reductions in total As load through organic amendments in boro rice grain and straw samples were manifested predominately through reduced accumulations of inorganic As species (As-III and As-V) among which As-V accounted for the largest share.",
Arsenic,1292191,"In vitro assessment on the impact of soil arsenic in the eight rice varieties of West Bengal, India Abstract: Rice is an efficient accumulator of arsenic and thus irrigation with arsenic-contaminated groundwater and soil may induce human health hazard via water-soil-plant-human pathway. A greenhouse pot experiment was conducted on three high yielding, one hybrid and four local rice varieties to investigate the uptake, distribution and phytotoxicity of arsenic in rice plant. 5, 10, 20, 30 and 40mgkg(-1) dry weights arsenic dosing was applied in pot soil and the results were compared with the control samples. All the studied high yielding and hybrid varieties (Ratna, IET 4094, IR 50 and Gangakaveri) were found to be higher accumulator of arsenic as compared to all but one local rice variety, Kerala Sundari. In these five rice varieties accumulation of arsenic in grain exceeded the WHO permissible limit (1.0mgkg(-1)) at 20mgkg(-1) arsenic dosing. Irrespective of variety, arsenic accumulation in different parts of rice plant was found to increase with increasing arsenic doses, but not at the same rate. A consistent negative correlation was established between soil arsenic and chlorophyll contents while carbohydrate accumulation depicted consistent positive correlation with increasing arsenic toxicity in rice plant.",
Arsenic,1360132,"Emission spectrographic determination of arsenic, antimony, cadmium, lead, copper and zinc in airborne particulates collected on glass fiber filter Abstract: HEEP COPYRIGHT: BIOL ABS. A fast, simple, precise and direct emission spectogrographic method was developed for the determination of As, Sb, Cd, Pb, Cu, and Fn in airborne particulates collected on glass fiber filter. Sample discs, punched out from the fiber filter, are packed in a boiler cap electrode. An internal standard solution (50mu1) containing 10 mug/ml In are added to dropwise on the discs. After evaporating the solution, the electrode is subjected to DC arc excitation (current: 15 A, analytical gap: 2mm, exposure time: 30 s with no preburn). The precision of the method is consistently better than plus or minus 12%.",
Arsenic,2298685,"Relationships of hair mineral concentrations with insulin resistance in metabolic syndrome Abstract: Mineral deficiencies can cause impaired insulin release and insulin resistance. This study was conducted to investigate the relationship between hair mineral concentrations and insulin resistance in patients with metabolic syndrome (MS). A total of 456 subjects (161 patients with MS and 295 subjects without MS) were reviewed, and fasting plasma glucose, triglycerides, HDL-cholesterol, homeostasis assessment model-insulin resistance (HOMA-IR), and hair mineral concentrations were analyzed. While hair sodium and potassium concentrations were significantly higher, the hair calcium, magnesium, and zinc concentrations were lower in the MS group than in the control group. Regarding toxic element measurements, the hair arsenic (As) and lead (Pb) concentrations were higher in the MS group than in the control group. The results of multiple regression analysis, after adjusting for age, showed significant relationships between the Na/Mg and Ca/P ratios and HOMA-IR (R (2)?=?0.109, p?&lt;?0.05). The Ca, Na, K, and B concentrations were also associated with HOMA-IR (R (2)?=?0.116, p?&lt;?0.05). The hair Na concentration was significantly associated with MS, even after adjusting for age, visceral adipose tissue, and HOMA-IR (OR 1.020; 95 % CI 1.001-1.040; p?=?0.036). Our findings suggest that hair mineral concentrations, such as calcium, magnesium, zinc, sodium, and potassium concentrations, may play a role in the development of insulin resistance.",
Arsenic,1597391,Toxicokinetics and Biotransformation of As(III) and As(V) in Eisenia fetida Abstract: ,
Arsenic,1018379,"Intercomparison of analytical methods for arsenic speciation in human urine Abstract: An intercomparison exercise was conducted for the quantification of arsenic species in spiked human urine. The primary objective of the exercise was to determine the variance among laboratories in the analysis of arsenic species such as inorganic As (As+3 and As+5), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). Laboratories that participated had previous experience with arsenic speciation analysis. The results of this interlaboratory comparison are encouraging. There is relatively good agreement on the concentrations of these arsenic species in urine at concentrations that are relevant to research on the metabolism of arsenic in humans and other mammals. Both the accuracy and precision are relatively poor for arsenic concentrations of less than about 5 micrograms/l.",
Arsenic,1338628,"Mercury, arsenic and selenium exposure levels in relation to fish consumption in the Mediterranean area Abstract: In order to assess mercury (Hg), selenium (Se) and arsenic (As) exposure in the Mediterranean area, total mercury (THg), monomethylmercury (MeHg), Se and As levels were measured in umbilical cord blood and breast milk from Italian (n=900), Slovenian (n=584), Croatian (n=234) and Greek (n=484) women. THg, MeHg, As, and Se levels were also determined in blood samples of the same mothers from Italy and Croatia. In addition, THg and MeHg were determined in the same women's hair from all the countries involved in this study and As and Se levels were determined in the mother's urine samples from Italy, Croatia and Greece. Besides recording the consumption of other food items, the frequencies of fish consumption were assessed by detailed food frequency questionnaires, since fish represents an important source of Hg, Se and As in humans. The highest levels of THg and As were found in cord blood (Med((THg))=5.8ng/g; Med((As))=3.3ng/g) and breast milk (Med((THg))=0.6ng/g; Med((As))=0.8ng/g) from Greek women, while the highest Se levels were found in cord blood (Med=113ng/g) from Italy. Significant linear correlations were found between Hg, Se and As in blood, cord blood and breast milk. In addition, significant relations were found between the frequencies of total fish consumption and biomarkers of As, MeHg and Se exposure, with the strongest Spearman rank coefficients between frequencies of total fish consumption and THg levels in cord blood (r(s)=0.442, p&lt;0.001) or THg levels in hair (r(s)=0.421, p&lt;0.001), and between frequencies of total fish consumption and As levels in cord blood (r(s)=0.350, p&lt;0.001). The differences in Hg and As exposure between countries were probably due to different amounts of fish consumption and the consumption of different species of fish of different origin, while the highest Se levels in women from Italy were probably the consequence of the more frequent consumption of different non specific food items. Moreover, fish consumption, the possible common source of As, Hg and Se intake, could explain the correlations between the elements determined in cord blood, mother's blood or breast milk.",
Arsenic,1250970,"Behavioural and Physiological Responses of Gammarus pulex Exposed to Cadmium and Arsenate at Three Temperatures: Individual and Combined Effects Abstract: This study aimed at investigating both the individual and combined effects of cadmium (Cd) and arsenate (AsV) on the physiology and behaviour of the Crustacean Gammarus pulex at three temperatures (5, 10 and15°C). G. pulex was exposed during 96 h to (i) two [Cd] alone, (ii) two [AsV] alone, and (iii) four combinations of [Cd] and [AsV] to obtain a complete factorial plane. After exposure, survival, [AsV] or [Cd] in body tissues, behavioural (ventilatory and locomotor activities) and physiological responses (iono-regulation of [Na(+)] and [Cl(-)] in haemolymph) were examined. The interactive effects (antagonistic, additive or synergistic) of binary mixtures were evaluated for each tested temperature using a predictive model for the theoretically expected interactive effect of chemicals. In single metal exposure, both the internal metal concentration in body tissues and the mortality rate increased along metallic gradient concentration. Cd alone significantly impaired both [Na(+)] and [Cl(-)] while AsV alone had a weak impact only on [Cl(-)]. The behavioural responses of G. pulex declined with increasing metal concentration suggesting a reallocation of energy from behavioural responses to maintenance functions. The interaction between AsV and Cd was considered as 'additive' for all the tested binary mixtures and temperatures (except for the lowest combination at 10°C considered as &quot;antagonistic&quot;). In binary mixtures, the decrease in both ventilatory and locomotor activities and the decline in haemolymphatic [Cl(-)] were amplified when respectively compared to those observed with the same concentrations of AsV or Cd alone. However, the presence of AsV decreased the haemolymphatic [Na(+)] loss when G. pulex was exposed to the lowest Cd concentration. Finally, the observed physiological and behavioural effects (except ventilation) in G. pulex exposed to AsV and/or Cd were exacerbated under the highest temperature. The discussion encompasses both the toxicity mechanisms of these metals and their interaction with rising temperature.",
Arsenic,1936137,"Surveillance of selected nutrients, additives and undesirables in commercial Norwegian fish feeds in the years 2000-2010 Abstract: ",
Arsenic,1597300,"Utilisation of chemically stabilized arsenic-contaminated soil in a landfill cover Abstract: The aim of the study was to determine if an As-contaminated soil, stabilized using zerovalent iron (Fe(0)) and its combination with gypsum waste, coal fly ash, peat, or sewage sludge, could be used as a construction material at the top layer of the landfill cover. A reproduction of 2 m thick protection/vegetation layer of a landfill cover using a column setup was used to determine the ability of the amendments to reduce As solubility and stimulate soil functionality along the soil profile. Soil amendment with Fe(0) was highly efficient in reducing As in soil porewater reaching 99 % reduction, but only at the soil surface. In the deeper soil layers (below 0.5 m), the Fe treatment had a reverse effect, As solubility increased dramatically exceeding that of the untreated soil or any other treatment by one to two orders of magnitude. A slight bioluminescence inhibition of Vibrio fischeri was detected in the Fe(0) treatment. Soil amendment with iron and peat showed no toxicity to bacteria and was the most efficient in reducing dissolved As in soil porewater throughout the 2 m soil profile followed by iron and gypsum treatment, most likely resulting from a low soil density and a good air diffusion to the soil. The least suitable combination of soil amendments for As immobilization was a mixture of iron with coal fly ash. An increase in all measured enzyme activities was observed in all treatments, particularly those receiving organic matter. For As to be stable in soil, a combination of amendments that can keep the soil porous and ensure the air diffusion through the entire soil layer of the landfill cover is required.",
Arsenic,1352622,"Transcriptional regulation of thioredoxin reductase 1 expression by cadmium in vascular endothelial cells: Role of NF-E2-related factor-2 Abstract: Thioredoxin reductase (TrxR) is a selenoprotein that catalyzes the reduction of the active site disulfide of thioredoxin (Trx), which regulates the redox status of the cells. In the present study, we found that TrxR1, one of the three TrxR isozymes, was induced by cadmium as well as tumor necrosis factor alpha (TNFalpha) in bovine arterial endothelial cells (BAEC), and investigated the mechanism of cadmium-induced TrxR1 expression. We here showed that cadmium, differently from TNFalpha, enhanced the promoter activity of the 5'-flanking region of human TrxR1 gene (nucleotides -1692 to +49). Deletion and site-directed mutation of antioxidant responsive element (ARE) (nucleotides -62 to -48) in this region abolished the response to cadmium. Overexpression of NF-E2-related factor-2 (Nrf2) augmented the TrxR1 promoter activity. In contrast, overexpression of the dominant negative mutant of Nrf2 suppressed cadmium-induced activation of TrxR1 promoter through the ARE. Chromatin immunoprecipitation (ChIP) assays showed that anti-Nrf2 antibody precipitated ARE from the chromatin of the cadmium-treated cells. These results indicated that cadmium-induced TrxR1 gene expression is mediated by the activation of Nrf2 transcription factor and its binding to ARE in the TrxR1 gene promoter. We further found that in addition to cadmium, the activators of Nrf2, such as diethyl maleate (DEM) and arsenite, induced both TrxR1 and Trx gene expression in BAEC. Nrf2 might play an important role in the regulation of the cellular Trx system consisting of Trx and TrxR.",
Arsenic,1021332,"Elk exposure to arsenic in geothermal watersheds of Yellowstone National Park, USA Abstract: Geothermal activity in Yellowstone National Park (WY, USA) (YNP) results in elevated levels of arsenic in surface waters, aquatic vegetation, and sediments in the Upper Madison River Basin. This study was conducted to determine concentrations of arsenic in the tissues, feces, and rumen contents of elk (Cervus elaphus) residing in the Madison-Firehole (MF) River basin, and to evaluate potential arsenic exposure pathways. Concentrations of total arsenic in MF elk were significantly higher than in control elk populations, and analysis of arsenic in surface waters, elk forage, sediments, and soils suggests that the predominant arsenic exposure pathways are forage species found in aquatic and riparian habitats. Analysis of arsenic species in selected plant and elk samples indicated that the ingested forms of arsenic are predominantly inorganic, while the appearance of dimethylarsonate in elk rumen and feces suggests that arsenic is subject to methylation reactions after ingestion, potentially contributing to arsenic detoxification. Arsenic:creatinine ratios of elk urine samples analyzed across three different winters increased during winter progression and were correlated with total snow water equivalent as an index of winter severity. Exposure to arsenic and other trace elements (fluorine) may contribute to the previously observed decreased life expectancy of MF elk relative to control populations.",
Arsenic,2149315,"Mining the American West INTRODUCTION Arsenic in the Wilderness, or Knowing Nature through Mining Abstract: ",
Arsenic,628364,"Effects of exposure protocols on induction of kinetochore-plus and -minus micronuclei by arsenite in diploid human fibroblasts Abstract: Arsenic, widely distributed in the environment, is a potent human carcinogen. Arsenite genotoxicity has been observed in a variety of cells and animal systems. However, the underlying mechanism is not completely clear. In this study, human fibroblasts (HFW) were treated with 1.25-10 microM arsenite for 24 h (low dose and long exposure) and 5-80 microM for 4 h (high dose and short exposure), and the arsenite accumulation, cytotoxicity, and micronucleus (MN) induction were examined. By these two different protocols, HFW cells showed equivalent levels of arsenite accumulation, but exhibited different kinetics of cell killing and different types of MN generation. Arsenite induced mainly kinetochore-positive MN (K+-MN) in HFW cells by low dose exposure whereas mainly kinetochore-negative MN (K--MN) was induced by high dose exposure. Catalase reduced both K+- and K--MN induced by these two exposure protocols. Except for the case of K+-MN induction by the high dose exposure protocol, N-acetyl-cysteine (NAC) in both low and high dose protocols was also shown to effectively reduce arsenite-induced MN. The present results imply that oxidative stress is involved in arsenite-induced MN in diploid human fibroblasts. However, different protocols for arsenite exposure may result in different cellular damage.",
Arsenic,1380781,"Rapid desensitization of B-cell receptor by a dithiol-reactive protein tyrosine phosphatase inhibitor: uncoupling of membrane IgM from syk inhibits signals leading to Ca2+ mobilization Abstract: B-cell antigen receptor (BCR)-mediated calcium response can be blocked by phenylarsine oxide (PAO), a dithiol group-reactive protein tyrosine phosphatase inhibitor. We have examined the mechanism of this inhibition in BL41 Burkitt lymphoma cells. PAO-dependent inhibition is not restricted to the BCR-mediated functions, as evidenced by the failure of the same cells to mobilize Ca2+ in response to CD19 cross-linking. In contrast, calcium response induced by a putative syk activator, H2O2, exhibited only a moderate sensitivity to PAO, demonstrating that PAO did not cause general suppression of all the functions leading to Ca2+ mobilization. BCR cross-linking or H2O2 treatment leads to the induction of almost complete non-responsiveness for the reciprocal stimulation. Since BCR cross-linking did not generate non-responsiveness to H2O2 in the presence of PAO, and PAO-treated cells remained responsive to syk activation by H2O2, we suppose that PAO may inhibit BCR-mediated signal transduction events upstream of syk activation. This assumption was supported by additional data, indicating that PAO was able to modulate functions of at least 2 different protein tyrosine kinase enzymes involved in BCR-mediated signaling. PAO induced rapid and dose-dependent tyrosine phosphorylation of lyn and selectively inhibited BCR-mediated tyrosine phosphorylation of syk. The results presented in this paper demonstrate that PAO may provoke cellular desensitization process by alteration of the signal transducer functions of lyn and syk tyrosine kinase enzymes.",
Arsenic,1337314,"Biosorption of arsenic in drinking water by submerged plant: Hydrilla verticilata Abstract: To evaluate the biosorption efficacy of submerged aquatic plant Hydrilla verticilata for arsenic uptake from drinking water. H. verticillata, a submerged aquatic plant was utilized successfully for arsenic uptake from aqueous solution. Batch studies with various parameters viz. pH, sorbent dose, contact time, initial metal ion concentration, and temperature were carried out. Data were utilized to plot Lagergren graph along with pseudo-second-order graphs for kinetic studies to estimate the removal efficacy and to determine the nature of reaction. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) have been performed for characterization of metals on biomass. The study showed 96.35 % maximum absorption of arsenic by H. verticilata at initial concentration of 100 ppb with 0.5 g of biomass/100 ml for 5 h contact time at pH?6.0 with 150 rpm agitation rate. Data followed Langmuir isotherm showing sorption to be monolayer on homogeneous surface of biosorbent. The negative values of ?G° indicated spontaneous nature; whereas ?H° indicates exothermic nature of system and negative value of ?S° entropy change correspond to a decrease in the degree of freedom to the adsorbed species followed by pseudo-second-order adsorption kinetics. FTIR and SEM results showed apparent changes in functional group regions after metal chelation and the changes in surface morphology of biosorbent. This is a comparatively more effective, economic, easily available, and environmentally safe source for arsenic uptake from solution due to its high biosorption efficacy than other biosorbents already used.",
Arsenic,1509354,"Removal of Arsenic from Waters using Montmorillonite KSF as Adsorbent Abstract: Montmorillonite can be used to remove arsenic for its rich resources, economy and easy availability. Thermal treated montmorillonite can increase the activity and the activation method is simple. In this work, the adsorption of As(V) on natural and thermal treated KSF was investigated. The influence of some parameters on the adsorption of As(V) such as thermal treatment temperature, initial pH value and KSF dosage was studied. The adsorption of As(V) on thermal treatment KSF did not significantly enhance. In the initial stage of adsorption, the rate was very quick and the adsorption capacities were increased rapidly, then the adsorption rate reduced gradually. The adsorption follows pseudo-second-order kinetics. Langmuir model fits the isotherm and the capacity was 26.7 mg/g. As(V) removal efficiency was significantly influenced by solution pH. The As(V) adsorption was more efficienct in the pH range 4.0-8.0 and As(V) was mainly adsorbed in the form of H2AsO4- and HAsO42-. The existence of SO42- and PO43- has a noticeable effect on the adsorption of arsenate. The formation of inner-sphere complexation is suggested.",
Arsenic,1029365,"Clinicopathologic conference; abdominal cramps, vomiting, shock, and unexpected death Abstract: ",
Arsenic,1020667,"Arsenite causes DNA damage in keratinocytes via generation of hydroxyl radicals Abstract: Arsenic is an environmental and occupational toxin. Dermatologic toxicities due to arsenic exposure are well-documented and include basal cell and squamous cell carcinomas. However, the mechanism of arsenic-induced skin cancer is not well-understood. Recent studies indicate that arsenic exposure results in the generation of reactive oxygen species (ROS) and oxidative stress. Here, we examined the chemical nature of the specific ROS, studied the interrelationship among these species, and identified the specific species that is responsible for the subsequent DNA damage in a spontaneously immortalized keratinocyte cell line. We detected the formation of O(2)(*)(-) and H(2)O(2) in keratinocytes incubated with arsenite [As(III)] but not with arsenate. As(III)-induced DNA damage was detected in a concentration-dependent manner and evident at low micromolar concentrations. Catalase, an H(2)O(2) scavenger, eliminated H(2)O(2) and reduced the As(III)-mediated DNA damage. Superoxide dismutase, by enhancing the production of H(2)O(2) and (*)OH, significantly increased the As(III)-mediated DNA damage. Sodium formate, a competitive scavenger for (*)OH, and deferoxamine, a metal chelator, both reduced the DNA damage. These results suggest that exposure to arsenite generates O(2)(*)(-) and H(2)O(2), and (*)OH, derived from H(2)O(2), is responsible, at least in part, for the observed DNA damage. These findings demonstrate arsenic-induced formation of specific ROS and provide the direct evidence of (*)OH-mediated DNA damage in keratinocytes, which may play an important role in the mechanism for arsenic-induced skin carcinogenicity.",
Arsenic,1292198,"Arsenate and arsenite exposure modulate antioxidants and amino acids in contrasting arsenic accumulating rice (Oryza sativa L.) genotypes Abstract: Carcinogenic arsenic (As) concentrations are found in rice due to irrigation with contaminated groundwater in South-East Asia. The present study evaluates comparative antioxidant property and specific amino acid accumulation in contrasting rice genotypes corresponding to differential As accumulation during arsenate (As(V)) and arsenite (As(III)) exposures. The study was conducted on two contrasting As accumulating rice genotypes selected from 303 genotype accessions, in hydroponic conditions. Maximum As accumulation was up to 1181?gg(-1) dw in the roots of high As accumulating genotype (HARG), and 89?gg(-1) dw in low As accumulating genotype (LARG) under As(III) exposures. The inorganic As was correlated more significantly upon exposures to As(III) than As(V). In the presence of As(V) various antioxidant enzymes guiacol peroxidase (GPX), ascorbate peroxidase (APX) and superoxide dismutase (SOD) were highly stimulated in HARG. The stress responsive amino acids proline, cysteine, glycine, glutamic acid and methionine showed higher accumulation in HARG than LARG. A clear correlation was found between stress responsive amino acids, As accumulation and antioxidative response. The comparisons between the contrasting genotypes helped to determine the significance of antioxidants and specific amino acid response to As stress.",
Arsenic,627212,"Pulmonary biomarkers based on alterations in protein expression after exposure to arsenic Abstract: OBJECTIVE: Environmental exposure to arsenic results in multiple adverse effects in the lung. Our objective was to identify potential pulmonary protein biomarkers in the lung-lining fluid of mice chronically exposed to low-dose As and to validate these protein changes in human populations exposed to As. METHODS: Mice were administered 10 or 50 ppb As (sodium arsenite) in their drinking water for 4 weeks. Proteins in the lung-lining fluid were identified using two-dimensional gel electrophoresis (n = 3) or multidimensional protein identification technology (MUDPIT) (n = 2) coupled with mass spectrometry. Lung-induced sputum samples were collected from 57 individuals (tap water As ranged from ~ 5 to 20 ppb). Protein levels in sputum were determined by ELISA, and As species were analyzed in first morning void urine. RESULTS: Proteins in mouse lung-lining fluid whose expression was consistently altered by As included glutathione-S-transferase (GST)-omega-1, contraspin, apolipoprotein A-I and A-IV, enolase-1, peroxiredoxin-6, and receptor for advanced glycation end products (RAGE). Validation of the putative biomarkers was carried out by evaluating As-induced alterations in RAGE in humans. Regression analysis demonstrated a significant negative correlation (p = 0.016) between sputum levels of RAGE and total urinary inorganic As, similar to results seen in our animal model. CONCLUSION: Combinations of proteomic analyses of animal models followed by specific analysis of human samples provide an unbiased determination of important, previously unidentified putative biomarkers that may be related to human disease.",
Arsenic,2345782,"Distribution and accumulation of arsenic in rice plants grown in arsenic-rich agricultural soil Abstract: The level of arsenic (As) in rice plants can be affected by the groundwater used for irrigation, type and concentration of As in the soil, and soil properties of paddy fields. In this study, the interrelationships among As levels in various parts of rice plants (Oryza sativa L.) and soils, as well as the As concentrations in soil pore water and groundwater in paddy fields that were irrigated with As-contained groundwater have been investigated at selected locations in an area where there was an endemic Blackfoot disease (BFD) before 1990, in the Chianan Plain of southwestern Taiwan. Results show that the total As concentrations in the groundwater used for irrigation of the sampled paddy fields at Hsuechia, Yichu, and Budai in the Chianan Plain are in the range of 32.9 to 175.7 mu g L-1. Arsenite is present in paddy soils under flooded conditions, as a result of As accumulation from irrigated groundwater, and this As has been taken up into the roots and translocated to the shoots and leaves of the rice plants. The translocation of As from roots to shoots is minor for all the sampled rice plants, keeping the As in the root system and allowing rice plants to survive in high As soil. The lower translocaton factor (&lt;0.05) for the translocation from roots to shoots indicates a lower proportion of As transfer from roots to the parts of the plant aboveground, suggesting that root tissues have a strong capability to hold As.",
Arsenic,627866,"Inorganic and methylated arsenic compounds induce cell death in murine macrophages via different mechanisms Abstract: We demonstrate in this study the cytotoxic effects of inorganic arsenicals, arsenite and arsenate, and organic arsenic compounds, monomethylarsonic acid (MAA), dimethylarsinic acid (DMAA), and trimethylarsine oxide (TMAO), which are metabolites of inorganic arsenicals in human bodies, using murine macrophages in vitro. Inorganic arsenicals, both arsenite and arsenate, are strongly toxic to macrophages, and the concentration that decreased the number of surviving cells to 50% of that in untreated controls (IC50) was 5 or 500 microM, respectively. These inorganic arsenicals mainly caused necrotic cell death with partially apoptotic cell death; about 80% of dead cells were necrotic, and 20% were apoptotic. The inorganic arsenicals also induced marked release of an inflammatory cytokine, tumor necrosis factor alpha (TNF alpha), at cytotoxic doses. This strong cytotoxicity of an inorganic arsenical, arsenite, might be mediated via active oxygen and protease activation because it was inhibited by the addition of some antioxidant reagents, such as superoxide dismutase (SOD), catalase, and GSH, or by a peptide inhibitor of interleukin-1 beta-converting enzyme (ICE). It is likely that these immunotoxic effects of inorganic arsenicals may evoke both immunosuppression and inflammation, and they may be central factors causing carcinogenesis and severe inflammatory responses, such as hepatomegaly and splenomegaly, in chronic arsenicosis patients who daily ingested arsenic-contaminated well water. In contrast, the cytotoxic effects of methylated arsenic compounds were lower than those of inorganic arsenicals. The IC50 value of DMAA was about 5 mM, and MAA and TMAO had no toxicity even at concentrations over 10 mM. Additionally, these methylated chemicals suppressed the TNFalpha release from macrophages. DMAA induced mainly apoptotic cell death in macrophages as indicated by cellular morphological changes, condensed nuclei, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL), and DNA fragmentation. However, the cytotoxicity of DMAA might be induced via a different mechanism from that of inorganic arsenicals because it was not abolished by the additions of SOD, catalase, or ICE inhibitor. Conversely, GSH enhanced the toxicity of DMAA. These data suggest that methylation of inorganic arsenicals in mammals plays an important role in suppression of both severe immunosuppression and inflammatory responses caused by inorganic arsenicals.",
Arsenic,1360106,"Effect of arsenic on the incorporation of 14C-thymidine into DNA of phytohaemagglutinin-treated lymphocytes Abstract: HEEP COPYRIGHT: BIOL ABS. In human lymphocyte cultures stimulated with phytohemagluttinin, Na2HAsO4, independent of the As doses used (10 mug, 30 mug, 50 mug/ml culture medium), increased the 14C-thymidine incorporation in acid precipitable biopolymers. The increase was 17 | 4% at 1 h exposure to As, compared with control cultures which were not exposed to As. The administration of 30 mug and 50 mug Na2HAsO4/ml medium at incubation periods between 2 and 18 h resulted in a decrease in the radioactive incorporation rate into the DNA which was dependent on dose and time. Using 10 mug Na2HAsO4/ml medium, the 1 h stimulation was followed by an inhibition (up to approximately 35%, control = 100%), which lasted approximately 3 h. This was followed by an increase in the 14C-thymidine incorporation into the DNA for a further 2 h. The course of the inhibition curve with 10 mug Na2HAsO4 and the results with exposure times between 6-18 h showed that the decreases were dependent on dose and time. The stimulation of the 14C-thymidine utilization by As, may be due to an increased repair activity. This may lead to a situation where (labeled) bases which are added outside the synthesis phase are incorporated into the DNA. The inhibition of 14C-thymidine incorporation which is dependent on dosage and time, with larger doses of As can be explained by a prevailing influence of enzymes of the synthesis system (e.g., polymer As), while the unusual course of the inhibition curve under the influence of 10 mug Na2HAsO4 showed that an activation and inhibition of enzyme systems (synthesis and repair) which was displaced in time, was taking place. Disturbances of the regulation processes of the DNA replication and the initiation overlap may be involved.",
Arsenic,1027672,Studies in the incidence of cancer in a factory handling inorganic compounds of arsenic: II. Clinical and environmental investigations Abstract: ,
Arsenic,2347661,"Influence of the interaction between phosphate and arsenate on periphyton's growth and its nutrient uptake capacity Abstract: Periphyton communities grown in microcosms were studied under the exposure to different arsenate (As) and phosphate (P) regimes with the aim of revealing the effect of chronic exposure to As on periphyton physiological and structural characteristics. Also, we aimed to study periphyton changes on sensitivity to As, exposed to different P and As regimes. As affected structural and functional parameters of periphyton communities starved of P, inhibiting algal growth, photosynthetic capacity, changing community composition and reducing the ability of the community to retain P. The effects of As on these parameters were only detected in P starved communities, showing that chronic exposure to As led to changes in the photosynthetic apparatus under the conditions of P-limitation, but not when P-availability was higher. This fact reveals a lower toxicity and/or a higher adaptation of the P-amended community. Intracellular As contents were higher in communities starved of P. However, As tolerance was only induced by the combination of As and P but not by As or P alone indicating that tolerance induction may be an ATP-dependent mechanism. This study reveals that chronic exposure of natural communities to environmentally realistic As concentrations will damage periphyton communities affecting key ecosystem processes, as P uptake, leading to changes in stream ecosystems, as these organisms play a key role in nutrient cycling through nutrient uptake and transfer to higher trophic levels.",
Arsenic,1030589,"Effects of leaves extract of Ocimum sanctum L. on arsenic-induced toxicity in Wistar albino rats Abstract: Therapeutic efficacy of oral administration of Ocimum sanctum (200mg/kg, once daily) post arsenic exposure (100 ppm in drinking water for 4 months) was investigated in rats. Animals exposed to arsenic (III) showed a significant inhibition of delta-aminolevulinic acid dehydratase (ALAD) activity, decrease in reduced glutathione (GSH) level and an increase in reactive oxygen species (ROS) in blood. On the other hand, a significant decrease in hepatic ALAD, and increase in delta-aminolevulinic acid synthetase activity were noted after arsenic exposure. These changes were accompanied by an increase TBARS level in liver and kidney. Activities of liver, kidney and brain superoxide dismutase and catalase also showed a decrease on arsenic exposure. Administration of O. sanctum post arsenic exposure, exhibited significant recovery in blood ALAD activity while, it restored blood GSH and ROS levels. Other blood biochemical variables remained unchanged on O. sanctum supplementation. Interestingly, there was a marginal, but significant depletion of arsenic from blood, liver and kidneys. The results conclude that post arsenic administration of O. sanctum has significant role in protecting animals from arsenic-induced oxidative stress and in the depletion of arsenic concentration. Further studies thus can be recommended for determining the effect of co-administrating of O. sanctum during chelating therapy with a thiol chelator.",
Arsenic,656871,"Supplementation of ascorbic acid prevents oxidative damages in arsenic-loaded hepatic tissue of rat: An ex vivo study Abstract: Oxidative stress due to arsenic toxicity and ameliorative potentiality of L-ascorbic acid was evaluated in an ex vivo system of rat hepatic tissue. The study revealed that arsenic increased the activity of superoxide dismutase (SOD) and catalase (CAT) and the level of lipid peroxidation (LPO), protein carbonyl (PC) and nitric oxide (NO) at 1 hour, 1.5 hours and 2 hours of incubation. Co-treatment with L-ascorbic acid was found effective to normalize the activity of SOD and CAT and the production of LPO, PC and NO in hepatic tissue. This ex vivo study suggested that ascorbic acid is helpful to ameliorate arsenic-induced oxidative stress. This may be one of the alternative screening systems to study the efficacy of antioxidant and hepatoprotective agent.",
Arsenic,2345855,Analysis of Nine Edible Clay Supplements with a Handheld XRF Analyzer Abstract: ,
Arsenic,1348357,"Influence of redox-active compounds and PXR-activators on human MRP1 and MRP2 gene expression Abstract: In the present study, we investigated the inducibility of the drug conjugate transporter genes MRP1 and MRP2 by redox-active compounds such as tertiary butylated hydroquinone (tBHQ) and quercetin and by chemicals known to activate the pregnane X receptor (PXR) such as rifampicin and clotrimazol and by the metalloid compound arsenite. The human MRP2 gene was found to be inducible in HepG2 cells by rifampicin, clotrimazol, arsenite and tBHQ. As MRP1 expression is extremely low in HepG2 cells, its inducibility was studied in MCF-7 cells. However, only tBHQ and quercetin acted as inducers, but not the other compounds investigated. Reporter gene assays demonstrated that proximal promoter regions of the genes contribute to the induction by tBHQ, quercetin (MRP1) and clotrimazol (MRP2). However, the deletion of binding sites supposed to mediate the induction process (a PXR-binding element-like sequence for the clotrimazol effect and an ARE (antioxidative response element) for the tBHQ/quercetin effect) did not result in a significant decrease in the induction factor indicating that other parts of the promoter are probably involved in the induction process. In summary, expression of both genes can be up-regulated by redox-active compounds, while the other compounds tested induced only MRP2 but not MRP1 expression.",
Arsenic,1292195,"Arsenic uptake in upland rice inoculated with a combination or single arbuscular mycorrhizal fungi Abstract: A pot trial was conducted to investigate the role of arbuscular mycorrhizal fungi (AMF) on arsenic (As) uptake of upland rice (Oryza sativa L.) cultivar, Zhonghan 221; where the following 3 species of Glomus geosporum (Gg), G. mosseae (Gm) and G. versiforme (Gv) were applied as single or combined inoculations. In general, Gm significantly enhanced (p&lt;0.05) total As concentration in Zhonghan 221 when compared to the non mycorrhizal (NM) treatment. The treatment inoculated with Gg+Gm increased total phosphorus (P) uptake and decreased total As uptake in the ingestible rice parts (husks and grains). In terms of AMF colonization rates, Gm had significantly higher (p&lt;0.05) average values of 57.3% and 66.6% when grown in As(0) and As(40) soils, respectively, in comparison to that of Gg and Gv, and finally dropped to 3.63% when grown in As(80) soil. There was a significant difference (p&lt;0.05) between single AMF species (Gg or Gv) and AMF mixture treatments (Gg+Gv, Gg+Gm, Gv+Gm and Gg+Gv+Gm) in terms of total As concentrations in rice. No significant correlation between AMF colonization rates and As uptake in grains (r=0.150, p&gt;0.01) and total P (r=0.002, p&gt;0.01) were observed.",
Arsenic,2149139,"Tocol composition and supercritical carbon dioxide extraction of lipids from barley pearling flour Abstract: Samples of whole grain and 35% pearling flour of 20 different barley varieties grown in Alberta were analyzed for their lipid contents. Total lipid contents of whole grains were within 1.9% to 3.0% (w/w), whereas those of the 35% pearling flour were 4.3% to 7.9%. Lipids of 35% pearling flour fraction of Tercel barley were extracted using supercritical carbon dioxide (SC-CO2 ) at different pressures (24, 45, and 58 MPa) and temperatures (40 and 60 °C) for 3 h. Lipid recoveries of 73% to 97% were achieved using SC-CO2 extraction under different operational conditions. Tocol contents and compositions of whole grain, 35% pearling flour, and SC-CO2 extracts were analyzed using HPLC. Tocol content of the whole grain was 53.8 to 124.9 ?g/g and that of the pearling flour was 195 to 363 ?g/g of flour. The hulless barley varieties were higher in tocols, with waxy, double waxy and Tercel varieties having the highest levels (P &lt; 0.05). The ratios of total tocotrienols to total tocopherols varied within 1.6 to 3.9 range. Tocol concentrations of SC-CO2 extract fractions varied from 1171 to 4391 ?g/g extract depending on the operational conditions. Barley oil is a good natural source of different tocol isomers rich in tocotrienols.",
Arsenic,1240471,"Arsenic removal from contaminated soil via biovolatilization by genetically engineered bacteria under laboratory conditions Abstract: In Rhodopseudomonas palustris, an arsM gene, encoding bacterial and archaeal homologues of the mammalian Cyt19 As(III) S-adenosylmethionine methytransferase, was regulated by arsenicals. An expression of arsM was introduced into strains for the methylation of arsenic. When arsM was expressed in Sphingomonas desiccabilis and Bacillus idriensis, it had 10 folds increase of methyled arsenic gas compared to wild type in aqueous system. In soil system, about 2.2%-4.5% of arsenic was removed by biovolatilization during 30 days. This study demonstrated that arsenic could be removed through volatilization from the contaminated soil by bacteria which have arsM gene expressed. These results showed that it is possible to use microorganisms expressing arsM as an inexpensive, efficient strategy for arsenic bioremediation from contaminated water and soil.",
Arsenic,485894,"Combined administration of N-acetylcysteine and monoisoamyl DMSA on tissue oxidative stress during arsenic chelation therapy Abstract: The present study deals with the therapeutic potential of combined administration of N-acetylcysteine (NAC) along with monoisoamyl DMSA (MiADMSA) against chronic arsenic poisoning in guinea pigs. Animal were exposed to 50 ppm arsenic in drinking water for 8 mo and subsequently treated for 5 consecutive days with 100 mg/kg NAC (orally) and MiADMSA (intraperitoneally), individually or in combination (50 mg/kg each). Arsenic exposure produced a significant depletion of blood delta-aminolevulinic acid dehydrate (ALAD) activity, increased the blood zinc protoporphyrin (ZPP) level, and reduced blood and liver glutathione (GSH) levels in guinea pigs. Hepatic oxidized glutathione (GSSG) and thiobarbituric acid reactive substance (TBARS) levels showed a marked increase, whereas hepatic alkaline phosphatase (ALP) activity decreased and acid phosphatase (ACP) activity increased on arsenic exposure. Significant depletion of liver transaminase activities on arsenic exposure suggests organ injury. Administration of MiADMSA, alone and in combination with NAC after arsenic exposure, was able to significantly enhance hepatic GSH and to red, ice GSSG and TBARS levels compared to the arsenic control. Biochemical variables indicative of liver injury generally remained insensitive to any of these treatments. The recoveries in parameters indicative of oxidative stress were more marked in guinea pigs treated with combined administration of NAC and MiADMSA than monotherapy. Interestingly, there was a more pronounced depletion of arsenic from, blood and tissues after combined treatment with NAC plus MiADMSA than MiADMSA. Blood and tissues copper, zinc, iron, and calcium concentrations showed a significant increase after arsenic exposure, which showed improvement, particularly after combined administration of MiADMSA and NAC. Based on these data, a proposal can be made that greater effectiveness in chelation treatment against chronic arsenic poisoning (i.e., turnover in the oxidative stress and removed of arsenic from the system) could be achieved by combined administration of an antioxidant (preferably having a thiol moiety) with MiADMSA.",
Arsenic,53231,"Trace element content of moonshine Abstract: Although the contamination of illicit whiskey with lead is widely accepted, the potential for exposure to other trace elements from drinking &quot;moonshine&quot; is less well appreciated. To better understand the potential for trace element poisoning, we undertook an analysis of samples of Georgia moonshine. Although a number of elements were not found in significant quantities to be considered harmful, four elements (copper, zinc, lead, and arsenic) were present in potentially toxic concentrations. The possible implications and sources of the contamination are discussed.",
Arsenic,2149197,"Crossing redox boundaries--Aquifer redox history and effects on iron mineralogy and arsenic availability Abstract: Cretaceous shallow marine sediments from northwestern Germany exhibit a distinct colour and geochemical boundary in a depth of several decametres, witnessing a terrestrial oxidative paleo redox process which resulted in cement loss and oxidation of Fe(II) phases. Sediment samples were obtained from boreholes drilled in near-coastal and further basinward paleo environments, including both reduced and oxidized redox facies, to characterize As and Fe occurrence in unaltered layers and redistributional consequences of the redox event. Geochemical and mineralogical composition and As fractionation were assessed. Arsenic resides in pyrite in the reduced section with a bulk rock maximum concentration of 39?gg(-1), calculated Aspyrite is ?0.2wt.%. Siderite concretions in the fine sands do not function as As sinks, neither does glauconite whose general As/Fe leaching behaviour was characterized. In the zone of redox transition, reduced and oxidized phases coexist and elevated As concentrations (up to 73?gg(-1)) with high proportions of reactive As were detected. Arsenic behaviour changes from relatively homogeneous Fe sulphide-control in the unaltered sediments to very heterogeneous Fe hydroxide-control above the paleo redox boundary. The studied characteristics determine recent As availability in the subsurface and must be considered during groundwater extraction from this highly important aquifer.",
Arsenic,1017769,Arsenic for the fool: An exponential connection Abstract: Anthropogenic arsenic is insidiously building up together with natural arsenic to a level unprecedented in the history of mankind. Arsenopyrite (FeAsS) is the principal ore of arsenic and gold in hard rock mines; it is formed by a coupled substitution of sulphur by arsenic in the structure of pyrite (FeS(2)) - nicknamed &quot;fool's gold&quot;. Other important sources of anthropogenic arsenic are fossil fuels such as coal and oil. Here I report on the first indication that the environmental concentration of total arsenic in topsoils - in the 7-18ppm range - is exponentially related to the prevalence and mortality of Alzheimer's disease and other dementias in European countries. This evidence defies the imputed absence of verified cases of human morbidity or mortality resulting from exposure to low-level arsenic in topsoils.,
Arsenic,1597288,"Water management affects arsenic and cadmium accumulation in different rice cultivars Abstract: Paddy rice (Oryza sativa L.) is a staple food and one of the major sources of dietary arsenic (As) and cadmium (Cd) in Asia. A field experiment was conducted to investigate the effects of four water management regimes (aerobic, intermittent irrigation, conventional irrigation and flooding) on As and Cd accumulation in seven major rice cultivars grown in Zhejiang province, east China. With increasing irrigation from aerobic to flooded conditions, the soil HCl-extractable As concentrations increased significantly and the HCl-extractable Cd concentrations decreased significantly. These trends were consistent with the As and Cd concentrations in the straw, husk and brown rice. Water management both before and after the full tillering stage affected As and Cd accumulation in the grains. The intermittent and conventional treatments produced higher grain yields than the aerobic and flooded treatments. Cd concentrations in brown rice varied 13.1-40.8 times and As varied 1.75-8.80 times among the four water management regimes. Cd and As accumulation in brown rice varied among the rice cultivars, with Guodao 6 (GD6) was a low Cd but high-As-accumulating cultivar while Indonesia (IR) and Yongyou 9 (YY9) were low As but high-Cd-accumulating cultivars. Brown rice Cd and As concentrations in the 7 cultivars were significantly negatively correlated. The results indicate that As and Cd accumulated in rice grains with opposite trends that were influenced by both water management and rice cultivar. Production of 'safe' rice with respect to As and Cd might be possible by balancing water management and rice cultivar according to the severity of soil pollution.",
Arsenic,2298726,"Identification and quantification of phytochelatins in roots of rice to long-term exposure: Evidence of individual role on arsenic accumulation and translocation Abstract: Rice has the predilection to take up arsenic in the form of methylated arsenic (o-As) and inorganic arsenic species (i-As). Plants defend themselves using i-As efflux systems and the production of phytochelatins (PCs) to complex i-As. Our study focused on the identification and quantification of phytochelatins by HPLC-ICP-MS/ESI-MS, relating them to the several variables linked to As exposure. GSH, 11 PCs, and As-PC complexes from the roots of six rice cultivars (Italica Carolina, Dom Sofid, 9524, Kitrana 508, YRL-1, and Lemont) exposed to low and high levels of i-As were compared with total, i-As, and o-As in roots, shoots, and grains. Only Dom Sofid, Kitrana 508, and 9524 were found to produce higher levels of PCs even when exposed to low levels of As. PCs were only correlated to i-As in the roots (r=0.884, P &lt;0.001). However, significant negative correlations to As transfer factors (TF) roots-grains (r= -0.739, P &lt;0.05) and shoots-grains (r= -0.541, P &lt;0.05), suggested that these peptides help in trapping i-As but not o-As in the roots, reducing grains' i-As. Italica Carolina reduced i-As in grains after high exposure, where some specific PCs had a special role in this reduction. In Lemont, exposure to elevated levels of i-As did not result in higher i-As levels in the grains and there were no significant increases in PCs or thiols. Finally, the high production of PCs in Kitrana 508 and Dom Sofid in response to high As treatment did not relate to a reduction of i-As in grains, suggesting that other mechanisms such as As-PC release and transport seems to be important in determining grain As in these cultivars.",
Arsenic,1027015,"Effects of nickel, chromate, and arsenite on histone 3 lysine methylation Abstract: Occupational exposure to nickel (Ni), chromium (Cr), and arsenic (As) containing compounds has been associated with lung cancer and other adverse health effects. Their carcinogenic properties may be attributable in part, to activation and/or repression of gene expression induced by changes in the DNA methylation status and histone tail post-translational modifications. Here we show that individual treatment with nickel, chromate, and arsenite all affect the gene activating mark H3K4 methylation. We found that nickel (1 mM), chromate (10 ?M), and arsenite (1 ?M) significantly increase tri-methyl H3K4 after 24 h exposure in human lung carcinoma A549 cells. Seven days of exposure to lower levels of nickel (50 and 100 ?M), chromate (0.5 and 1 microM) or arsenite (0.1, 0.5 and 1 ?M) also increased tri-methylated H3K4 in A549 cells. This mark still remained elevated and inherited through cell division 7 days following removal of 1 ?M arsenite. We also demonstrate by dual staining immunofluorescence microscopy that both H3K4 tri-methyl and H3K9 di-methyl marks increase globally after 24 h exposure to each metal treatment in A549 cells. However, the tri-methyl H3K4 and di-methyl H3K9 marks localize in different regions in the nucleus of the cell. Thus, our study provides further evidence that a mechanism(s) of carcinogenicity of nickel, chromate, and arsenite metal compounds may involve alterations of various histone tail modifications that may in turn affect the expression of genes that may cause transformation.",
Arsenic,2088481,"Assessment of liver function in two groups of outdoor workers exposed to arsenic Abstract: <strong>PURPOSE: </strong>To evaluate whether the exposure to arsenic (As) causes alterations of liver enzymes in two groups of outdoor workers.<br /><br /><strong>METHODS: </strong>Total urinary As and the levels of AST/GOT, ALT/GPT, and GGT were measured on 80 traffic policemen and 50 police drivers. Personal air samples were obtained for assessing the exposure to As on a subgroup of 20 traffic policemen and 20 police drivers.<br /><br /><strong>RESULTS: </strong>Mean values of personal exposure to As, urinary As, AST/GOT, and ALT/GPT were significantly higher in traffic policemen than in the police drivers. Multiple linear regression models showed associations between urinary As and airborne As, ALT/GPT and the job variables, and BMI and urinary As.<br /><br /><strong>CONCLUSIONS: </strong>These findings contribute toward the evaluation of the hepatic effects of exposure to As in the urban workers.",
Arsenic,735109,"Arsenate and dimethylarsinic acid in drinking water did not affect DNA damage repair in urinary bladder transitional cells or micronuclei in bone marrow Abstract: Arsenic is a human skin, lung, and urinary bladder carcinogen, and may act as a cocarcinogen in the skin and urinary bladder. Possible modes of action of arsenic carcinogenesis/cocarcinogenesis include oxidative stress induction and inhibition of DNA damage repair. We investigated the effects of arsenic in drinking water on DNA damage repair in urinary bladder transitional cells and on micronucleus formation in bone marrow. F344 rats were given 100 ppm arsenate [As(V)] or dimethylarsinic acid [DMA(V)] in drinking water for 1 week. The in vivo repair of cyclophosphamide (CP)-induced DNA damage resulting from a single oral gavage of CP, and the in vitro repair of hydrogen peroxide (H(2)O(2))- or formaldehyde-induced DNA damage, resulting from adding H(2)O(2) or formaldehyde into cell medium, were measured by the Comet assay. DMA(V) effects were not observed on either CP-induced DNA damage induction or on DNA repair. Neither DMA(V) nor As(V) increased the H(2)O(2)- or formaldehyde-induced DNA damage, and neither inhibited the repair of H(2)O(2)-induced DNA damage. Neither DMA(V) nor As(V) increased the micronucleus frequency, nor did they elevate micronucleus frequency resulting from CP treatment above the level observed by the treatment with CP alone. These results suggest that arsenic carcinogenesis/cocarcinogenesis in the urinary bladder may not be via DNA damage repair inhibition. To our knowledge this is the first report of arsenic effects on DNA damage repair in the urinary bladder.",
Arsenic,1070315,"Environmental impact of flood: The study of arsenic speciation in exchangeable fraction of flood deposits of Warta river (Poland) in determination of &quot;finger prints&quot; of the pollutants origin and the ways of the migration Abstract: The paper presents the application of the hyphenated technique - high-performance liquid chromatography with atomic absorption spectrometry detection with hydride generation (HPLC-HG-AAS) - in the determinations of inorganic forms of arsenic: As(III) and As(V) in the exchangeable fraction of flood deposits. The separation of analytical signals of the determined arsenic forms was obtained using an ion-exchange column in a chromatographic system with the atomic absorption spectrometer as a detector, at the determination limits of 5ngg(-1) for As(III) and 10ngg(-1) for As(V). Flood deposits were collected after big flood event in valley of the Warta river which took place in summer 2010. Samples of overbank deposits were taken in Pozna? agglomeration and vicinity (NW Poland). The results of determinations of arsenic forms in the exchangeable fraction of flood deposits allowed indication of a hypothetical path of deposits migration transported by a river during flood and environmental threats posed by their deposition by flood.",
Arsenic,627461,"Decreased DNA repair gene expression among individuals exposed to arsenic in United States drinking water Abstract: Arsenic is well established as a human carcinogen, but its precise mechanism of action remains unknown. Arsenic does not directly damage DNA, but may act as a carcinogen through inhibition of DNA repair mechanisms, leading indirectly to increased mutations from other DNA damaging agents. The molecular mechanism underlying arsenic inhibition of nucleotide excision repair after UV irradiation (Hartwig et al., Carcinogenesis 1997;18:399-405) is unknown, but could be due to decreased expression of critical genes involved in nucleotide excision repair of damaged DNA. This hypothesis was tested by analyzing expression of repair genes and arsenic exposure in a subset of 16 individuals enrolled in a population based case-control study investigating arsenic exposure and cancer risk in New Hampshire. Toenail arsenic levels were inversely correlated with expression of critical members of the nucleotide excision repair complex, ERCC1 (r(2) = 0.82, p < 0.0001), XPF (r(2) = 0.56, p < 0.002), and XPB (r(2) = 0.75, p < 0.0001). The internal dose marker, toenail arsenic level, was more strongly associated with changes in expression of these genes than drinking water arsenic concentration. Our findings, based on human exposure to arsenic in a US population, show an association between biomarkers of arsenic exposure and expression of DNA repair genes. Although our findings need verification in a larger study group, they are consistent with the hypothesis that inhibition of DNA repair capacity is a potential mechanism for the co-carcinogenic activity of arsenic.",
Arsenic,1019782,"Protective role of ascorbic acid and alpha-tocopherol on arsenic-induced microsomal dysfunctions Abstract: Arsenic, a naturally occurring element, is present in food, soil, air and water. All human populations are exposed to arsenic and its compounds through occupational or environmental processes. Since arsenic compounds have been shown to exert their toxicity chiefly by generating reactive oxygen species, we have evaluated the effect of ascorbic acid and alpha-tocopherol on oxidative damage, antioxidant status and on xenobiotic metabolizing systems in arsenic-exposed rat liver and kidney microsomes. Arsenic exposure increases oxidative damage to lipids and proteins and decreases the levels of antioxidants and the activities of xenobiotic metabolizing enzymes. Coadministration of ascorbic acid and alpha-tocopherol to arsenic-exposed rats resulted in a reduction in the levels of lipid peroxidation, protein carbonyls and hydrogen peroxide and an elevation in the levels of reduced glutathione, ascorbic acid and alpha-tocopherol. Ascorbic acid and alpha-tocopherol treatment decreases the activity of haem oxygenase, whereas it increases the levels/ activity of cytochrome P450, cytochrome b5 and NADPH-cytochrome P450 reductase in arsenic-intoxicated rats. The results of this study provide evidence that ascorbic acid and alpha-tocopherol supplementation can improve the arsenic-induced altered microsomal functions in liver and kidney.",
Arsenic,2347754,"Time to revisit arsenic regulations: comparing drinking water and rice Abstract: Background: Current arsenic regulations focus on drinking water without due consideration for dietary uptake and thus seem incoherent with respect to the risks arising from rice consumption. Existing arsenic guidelines are a cost-benefit compromise and, as such, they should be periodically re-evaluated. <br> <br>Discussion: Literature data was used to compare arsenic exposure from rice consumption relative to exposure arising from drinking water. Standard risk assessment paradigms show that arsenic regulations for drinking water should target a maximum concentration of nearly zero to prevent excessive lung and bladder cancer risks (among others). A feasibility threshold of 3 mu g As l(-1) was determined, but a cost-benefit analysis concluded that it would be too expensive to target a threshold below 10 mu g As l(-1). Data from the literature was used to compare exposure to arsenic from rice and rice product consumption relative to drinking water consumption. The exposure to arsenic from rice consumption can easily be equivalent to or greater than drinking water exposure that already exceeds standard risks and is based on feasibility and cost-benefit compromises. It must also be emphasized that many may disagree with the implications for their own health given the abnormally high cancer odds expected at the cost-benefit arsenic threshold. <br> <br>Summary: Tighter drinking water quality criteria should be implemented to properly protect people from excessive cancer risks. Food safety regulations must be put in place to prevent higher concentrations of arsenic in various drinks than those allowed in drinking water. Arsenic concentrations in rice should be regulated so as to roughly equate the risks and exposure levels observed from drinking water.",
Arsenic,2278583,"Water treatment residues as accumulators of oxoanions in soil. Sorption of arsenate and phosphate anions from an aqueous solution Abstract: Here we report a survey addressed to determine, at different pH values (pH 4.0, 7.0 and 9.0), the ability of two different water treatment residues, a Fe-based (Fe-WTR) and an Al-based (Al-WTR), to accumulate arsenate and phosphate anions from an aqueous solution and to define the mechanism which regulate the sorption of these anions. Fe-WTR showed a greater As(V) and P(V) sorption capacity respect to Al-WTR at all the pH values investigated, in particular at pH 4.0. The greater capacity of the Fe-WTR to accumulate phosphate at pH 4.0 seems to be linked to the higher content of manganese ions compared to Al-WTR, which can give rise, with phosphate ions, to the formation of MnHPO4 precipitates. Sequential extraction of As(V)- or P(V)-WTRs suggested that the main mechanism governing the sorption of both two anions likely involve the formation of inner-sphere surface complexes [Fe/Al-O-As(P)]. Such a coordination mode was supported by the FT-IR spectra that exhibit well resolved band at 865cm(-1) and 1040cm(-1) attributable to ?(As-O) or ?(P-O) stretching vibration, respectively.",
Arsenic,1508648,"Tissue Distribution and Correlation Profiles of Heavy-Metal Accumulation in the Freshwater Crayfish Astacus leptodactylus Abstract: The present work details the analysis of heavy-metal and metalloid concentrations in exoskeleton, gill, hepatopancreas, and abdominal muscle tissues of 60 crayfish (Astacus leptodactylus) specimens collected from Lake Hirfanl?, a dam lake located in K?r?ehir (Turkey) with a low metal-contamination profile. Concentrations of 11 metals (aluminum [Al], chromium [Cd], manganese [Mn], cobalt [Co], nickel [Ni], copper [Cu], molybdenum [Mo], silver [Ag], cadmium [Cd], mercury [Hg], and lead [Pb]) and a metalloid (arsenic [As]) were measured by inductively coupled plasma-mass spectrometry, and the relative frequencies of the most abundant isotopes of Cr, Cu, Ag, Cd, Hg, and Pb were evaluated. Three correlation trends were evaluated between the following: (1) different elements in the each individual tissue, (2) individual elements in different tissues, and (3) different elements in different tissues. In addition, correlation rates of growth parameters (weight, cephalothorax length, and total length) with heavy-metal and metalloid concentrations in each tissue were investigated. Our results suggest that substantial differences in metal and metalloid-accumulation levels exist between male and female specimens, with stronger correlations between the heavy-metal concentrations observed in the male cohort. It is notable that correlation trends of Co, Cu, (52)As, Cr, and Ni in exoskeleton of the male specimens display strong similarities. Likewise, a very strong correlation is present in Ni-Cd and Ni-Pb accumulations in abdominal muscle of the male specimens; a similar trend is present between Cd and Pb concentrations in the same tissue of female specimens. For correlation rates of different heavy metals and metalloid in different tissues, the strongest positive association observed was between (63)Cu in gill and As in hepatopancreas, whereas the strongest negative correlation was between accumulated Ni in abdominal muscle and As in exoskeleton. Strong correlations between metals and metalloid accumulations were observed between exoskeleton and gill. In many cases, metal and metalloid accumulation was negatively correlated with growth parameters. Preferential accumulation of Cr and Cu isotopes was observed in different tissues, suggesting that significant amounts of isotope fractionation occur during heavy-metal accumulation. Relatively low correlation rates were observed between (52)Cr/(53)Cr and (63)Cu/(65)Cu concentrations in several tissue types in both male and female cohorts, whereas no such trend was observed between Cd and Pb isotopes.",
Arsenic,1017219,"Global DNA methylation in the mouse liver is affected by methyl deficiency and arsenic in a sex-dependent manner Abstract: Arsenic, a carcinogen, is assumed to induce global DNA hypomethylation by consuming the universal methyl donor S-adenosylmethionine (SAM) in the body. A previous study reported that a methyl-deficient diet (MDD) with arsenic intake greatly reduced global DNA methylation (the content of 5-methylcytosine) in the liver of male C57BL/6 mice. In the present study, we investigated the DNA methylation level, SAM content, and expression of DNA methyltransferases (DNMTs) in the liver of male and female C57BL/6 mice fed a methyl-sufficient diet (MSD), an MDD, or an MDD + arsenic. The DNA methylation level was accurately determined by measuring the content of genomic 5-methyldeoxycytidine (5medC) by high-performance liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) using stable-isotope-labeled 5medC and deoxycytidine (dC) as internal standards. The results of this study revealed that while the MDD and arsenic tended to reduce the genomic 5meC content in the male mice livers, the MDD + arsenic significantly increased the 5meC content in the female mice livers. Another unexpected finding was the small differences in 5meC content among the groups. The MDD and MDD + arsenic suppressed DNMT1 expression only in the male mice livers. In contrast, SAM content was reduced by the MDD and MDD + arsenic only in the livers of female mice, showing that the changes in 5meC content were not attributable to SAM content. The sex-dependent changes in 5meC content induced by methyl deficiency and arsenic may be involved in differences in male and female susceptibility to diseases via epigenetic modification of physiological functions.",
Arsenic,1366243,"Evaluation of arsine generation in arsenic field kit Abstract: The recent outbreak of arsenic in groundwater of Bangladesh has prompted the widespread use of arsenic field kits. The kit involves the generation of arsine (AsH3) from inorganic arsenic species by reduction with Zn and HCl. The arsine then reacts with a test strip containing HgBr2 to produce a color that is compared with a color scale for quantitation. It is known that arsine gas is one of the most toxic substances known to man. The objective of this work is to measure the concentration of ambi l can be more than 9 times above the 50 ppbv threshold limiting value (TLV). Actual kit experiments show that 50% of the arsine escapes the reaction cell during the test. We estimate that the maximum arsine concentration in the immediate vicinity of the kit can be more than 35 times TLV of arsine from a single experiment with 100 ppb total arsenic in solution. Particularly, field workers performing a large number of tests in highly affected areas are exposed to a much higher level of arsine. We suggest that the tests should be performed in well-ventilated places and that the worker should be provided with a gas mask to minimize arsine inhalation.",
Arsenic,1373127,"Thioredoxin and NADP-thioredoxin reductase from cultured carrot cells Abstract: Dark-grown carrot (Daucus carota L.) tissue cultures were found to contain both protein components of the NADP/thioredoxin system--NADP-thioredoxin reductase and the thioredoxin characteristic of heterotrophic systems, thioredoxin h. Thioredoxin h was purified to apparent homogeneity and, like typical bacterial counterparts, was a 12-kdalton (kDa) acidic protein capable of activating chloroplast NADP-malate dehydrogenase (EC 1.1.1.82) more effectively than fructose-1,6-bisphosphatase (EC 3.1.3.11). NADP-thioredoxin reductase (EC 1.6.4.5) was partially purified and found to be an arsenite-sensitive enzyme composed of two 34-kDa subunits. Carrot NADP-thioredoxin reductase resembled more closely its counterpart from bacteria rather than animal cells in acceptor (thioredoxin) specificity. Upon greening of the cells, the content of NADP-thioredoxin-reductase activity, and, to a lesser extent, thioredoxin h decreased. The results confirm the presence of a heterotrophic-type thioredoxin system in plant cells and raise the question of its physiological function.",
Arsenic,1704106,Synthetic phytochelatins complement a phytochelatin-deficient Arabidopsis mutant and enhance the accumulation of heavy metal(loid)s Abstract: ,
Arsenic,1936099,"Multidimensional growth measurements of abdominal aortic aneurysms Abstract: <strong>BACKGROUND: </strong>Monitoring the expansion of abdominal aortic aneurysms (AAAs) is critical to avoid aneurysm rupture in surveillance programs, for instance. However, measuring the change of the maximum diameter over time can only provide limited information about AAA expansion. Specifically, regions of fast diameter growth may be missed, axial growth cannot be quantified, and shape changes of potential interest for decisions related to endovascular aneurysm repair cannot be captured.<br /><br /><strong>METHODS: </strong>This study used multiple centerline-based diameter measurements between the renal arteries and the aortic bifurcation to quantify AAA growth in 51 patients from computed tomography angiography (CTA) data. Criteria for inclusion were at least 1 year of patient follow-up and the availability of at least two sufficiently high-resolution CTA scans that allowed an accurate three-dimensional reconstruction. Consequently, 124 CTA scans were systematically analyzed by using A4clinics diagnostic software (VASCOPS GmbH, Graz, Austria), and aneurysm growth was monitored at 100 cross-sections perpendicular to the centerline.<br /><br /><strong>RESULTS: </strong>Monitoring diameter development over the entire aneurysm revealed the sites of the fastest diameter growth, quantified the axial growth, and showed the evolution of the neck morphology over time. Monitoring the development of an aneurysm's maximum diameter or its volume over time can assess the mean diameter growth (r = 0.69, r = 0.77) but not the maximum diameter growth (r = 0.43, r = 0.34). The diameter growth measured at the site of maximum expansion was ?16%/y, almost four times larger than the mean diameter expansion of 4.4%/y. The sites at which the maximum diameter growth was recorded did not coincide with the position of the maximum baseline diameter (? = 0 .12; P = .31). The overall aneurysm sac length increased from 84 to 89 mm during the follow-up (P &lt; .001), which relates to the median longitudinal growth of 3.5%/y. The neck length shortened, on average, by 6.2% per year and was accompanied by a slight increase in neck angulation.<br /><br /><strong>CONCLUSIONS: </strong>Neither maximum diameter nor volume measurements over time are able to measure the fastest diameter growth of the aneurysm sac. Consequently, expansion-related wall weakening might be inappropriately reflected by this type of surveillance data. In contrast, localized spots of fast diameter growth can be detected through multiple centerline-based diameter measurements over the entire aneurysm sac. This information might further reinforce the quality of aneurysm surveillance programs.",
Arsenic,2279478,"Magnetic mesoporous Fe/carbon aerogel structures with enhanced arsenic removal efficiency Abstract: Wastewater treatment has drawn significant research attention due to its associated environmental issues. Adsorption is a promising method for treating wastewater. The development of an adsorbent with a high surface area is important. Therefore, we successfully developed mesoporous Fe/carbon aerogel (CA) structures with high specific surface areas of 487m(2)/g via the carbonization of composite Fe3O4/phenol-formaldehyde resin structures, which were prepared using a hydrothermal process with the addition of phenol. The mesoporous Fe/CA structures were further used for the adsorption of arsenic ions with a maximum arsenic-ion uptake of calculated 216.9mg/g, which is higher than that observed for other arsenic adsorbents. Ferromagnetic behavior was observed for the as-prepared mesoporous Fe/CA structures with an excellent response to applied external magnetic fields. As a result, the adsorbent Fe/CA structures can be easily separated from the solution using an external magnetic field. This study develops the mesoporous Fe/CA structures with high specific surface areas and an excellent response to an applied external magnetic field to provide a feasible approach for wastewater treatment including the removal of arsenic ions.",
Arsenic,1508537,"Nonischemic Mitral Regurgitation: Prognostic Value of Nonsustained Ventricular Tachycardia after Mitral Valve Surgery Abstract: Background: Nonsustained ventricular tachycardia (VT), frequent in unoperated severe mitral regurgitation (MR), confers mortality risk [sudden death (SD) and cardiac death (CD)]. The prognostic value of VT after mitral valve surgery (MVS) is unknown; we aimed to define this prognostic value and to assess its modulation by left (LV) and/or right (RV) ventricular ejection fraction (EF) for mortality after MVS. Methods: In 57 patients (53% females, aged 58 ± 12 years) with severe MR prospectively followed before and after MVS, we performed 24-hour ambulatory electrocardiograms approximately annually. LVEF and RVEF were determined within 1 year after MVS by radionuclide cineangiography. Results: During 9.52 ± 3.49 endpoint-free follow-up years, late postoperative CD occurred in 11 patients (7 SD, 4 heart failures). In univariable analysis, &gt;1 VT episode after MVS predicted SD (p &lt; 0.01) and CD (SD or heart failure; p &lt; 0.04). Subnormal postoperative RVEF predicted CD (p &lt; 0.04). When adjusted for preoperative age, gender, etiology or antiarrhythmics, both postoperative VT and RVEF predicted CD (p ? 0.05). When postoperative VT and RVEF were both in the multivariable model, only subnormal RVEF predicted CD (p &lt; 0.04). Among those with normal RVEF, VT &gt;1 episode predicted SD (p = 0.03). Conclusion: Postoperative VT and subnormal RVEF predict late postoperative deaths in nonischemic MR. Their assessment may aid patient management.",
Arsenic,383542,"European bee-eater (Merops apiaster) populations under arsenic and metal stress: Evaluation of exposure at a mining site Abstract: Two populations of the European bee-eater were studied, one living at a reference site and the other at a metal mining site. The concentration of arsenic and 11 metals (Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) was measured in feathers and regurgitated pellets collected at both sites. Cadmium, chromium, mercury, nickel, and lead were at least twofold higher in feathers of birds from the contaminated site than in the reference site, suggesting that this population was exposed to higher metal levels. Similarly, levels of aluminum, arsenic, cadmium, cobalt, chromium, iron, and lead were also at least twofold higher in pellets from the contaminated area. The obtained results suggested that the impacted population of Merops apiaster is at risk due to the exposure to some metals.",
Arsenic,2064240,"Surgical management of subungual melanoma: mayo clinic experience of 124 cases Abstract: <strong>BACKGROUND: </strong>Optimal surgical management of subungual malignant melanoma (SMM) has been debated.<br /><br /><strong>METHODS: </strong>Our tumor registry was reviewed for surgically treated cases of SMM from 1914 to 2010. Resection levels were compared with outcome.<br /><br /><strong>RESULTS: </strong>During a 96-year period, 124 cases of SMM were identified (65 men and 59 women). Mean age at diagnosis was 58 years. Mean length of symptoms before diagnosis was 2.2 years. Lesions occurred on the hand (n = 79) and foot (n = 45). The thumb (33.8%) and hallux (25.0%) were affected most. At diagnosis, most had local (83.9%) and regional nodal involvement (12.9%). Mean follow-up was 9.4 years.Mean Breslow depth was 3.1 mm. Amputations were most commonly performed on the thumb at the proximal phalanx or metacarpophalangeal joint (43.9%), and on the hallux at the proximal phalanx or metatarsophalangeal joint (69.0%).Disease progression occurred in 61 (49.2%) patients, and most commonly occurred as regional nodal (62.3%) and distant metastasis (42.6%). Disease progression-free survival rates at 5, 10, and 15 years were 57.1%, 49.9%, and 47.0%, respectively. Fifty-three patients died of melanoma-related causes. Disease-specific survival rates at 5, 10, and 15 years after surgery were 59.3%, 49.3%, and 45.2%. Overall survival rates at 5, 10, and 15 years were 60.5%, 43.8%, and 33.1%.In 116 patients who underwent amputation, resection level outcome analysis with univariate and multivariate analysis adjusting for tumor depth and clinical involvement demonstrated that level of resection was not significantly associated with progression-free, overall, or disease-specific survival.<br /><br /><strong>CONCLUSIONS: </strong>Diagnosis of subungual melanoma is often delayed and carries a poor prognosis. Conservative resections are warranted as resection level does not influence outcome when histologically free margins are obtained. Amputation through the proximal phalanx or the metatarsophalangeal joint is required in the hallux and toes. Fingers require resection through the distal interphalangeal joint. For the thumb, although resection through the interphalangeal joint proved adequate, secondary efforts should be directed toward maximizing function and quality of life. Function-preserving resections in the thumb with nail removal, partial distal phalanx resection, and volar flap reconstruction are easily performed and preserve length, maximize joint and sensory function, and improve cosmesis.",
Arsenic,1070366,"Major and minor arsenic compounds accounting for the total urinary excretion of arsenic following intake of blue mussels (Mytilus edulis): A controlled human study Abstract: Blue mussels (Mytilus edulis) accumulate and biotransform arsenic (As) to a larger variety of arsenicals than most seafood. Eight volunteers ingested a test meal consisting of 150g blue mussel (680?g As), followed by 72h with an identical, low As controlled diet and full urine sampling. We provide a complete speciation, with individual patterns, of urinary As excretion. Total As (tAs) urinary excretion was 328±47?g, whereof arsenobetaine (AB) and dimethylarsinate (DMA) accounted for 66% and 21%, respectively. Fifteen minor urinary arsenicals were quantified with inductively coupled plasma mass spectrometry (ICPMS) coupled to reverse-phase, anion and cation-exchange high performance liquid chromatography (HPLC). Thio-arsenicals and non-thio minor arsenicals (including inorganic As (iAs) and methylarsonate (MA)) contributed 10% and 7% of the total sum of species excretion, respectively, but there were large individual differences in the excretion patterns. Apparently, formation of thio-arsenicals was negatively correlated to AB formation and excretion, possibly indicating a metabolic interrelationship. The results may be of toxicological relevance since DMA and MA have been classified as possibly carcinogenic, and six of the excreted As species were thio-arsenicals which recently have been recognized as toxic, while iAs toxicity is well known.",
Arsenic,1508722,"Why we should talk about compliance with assisted reproductive technologies (ART): A systematic review and meta-analysis of ART compliance rates Abstract: BACKGROUND The goal of this systematic review and meta-analysis was to estimate the rate of compliance with assisted reproductive technologies (ART) and examine its relationship with treatment success rates. METHODS Six databases were systematically searched from 1978 to December 2011. Studies were included if they reported data on patient progression through three consecutive standard ART cycles. Compliance was estimated for the first three ART cycles (typical ART Regimen Compliance, TARC) and after the first and the second failed cycles (CAF1, CAF2). Treatment success rates for all patients who started ART and for those who fully complied with the three ART cycles were estimated. RESULTS Ten studies with data for 14 810 patients were included. TARC was 78.2% [95% confidence interval (CI) 68.8-85.3%], CAF1 was 81.8% (73.3-88.1%) and CAF2 was 75.3% (68.2-81.2%). The overall success rate was 42.7% (32.6-53.6%) for all patients starting ART and 57.9% (49.4-65.9%) for those who complied with three ART cycles. Compliance rates did not vary according to study quality, but TARC was higher for studies that reported data on doctor-censored patients versus those that did not (84.2% 95% CI 75.5-90.2 versus 70.6% 95% CI 58.3-80.5, P = 0.043). Analysis of funnel plots and the Egger test indicated publication bias for CAF1. CONCLUSIONS Findings from this meta-analysis should reassure clinics and patients that most patients are able to comply with three cycles of ART. Compliers could increase their chances of success by as much as 15%. A more detailed assessment of compliance requires monitoring long-term treatment trajectories through the creation of national registries.",
Arsenic,1380233,EFFECT OF ARSENIC ON CARBOHYDRATE METABOLISM AFTER SINGLE OR REPEATED INJECTION IN GUINEA-PIGS Abstract: BIOSIS COPYRIGHT: BIOL ABS. RRM TOXICITY GLYCOGEN DEPLETION LIVER,
Arsenic,1032474,"Role of heat-shock proteins in the induction of thermotolerance in Chinese hamster V79 cells by heat and chemical agents Abstract: To examine the involvement of heat shock proteins in the induction of thermotolerance in Chinese hamster V79 cells, thermotolerance was induced by heating of the cells at 42 degrees C for 4 h or at 44 degrees C for 20 min, or by treatment of the cells with 50 microM sodium arsenite for 3 h or 20 micrograms/ml puromycin for 4 h. Under unstressed conditions V79 cells synthesized constitutively three major heat-shock proteins, hsp70, hsp85 and hsp105. On exposure to conditions under which thermotolerance was induced, the synthesis of constitutive hsp70, hsp85 and hsp105 increased, but the inducible form of hsp70 was not synthesized, indicating that this inducible form was not necessary for the induction of thermotolerance. Although the amounts of heat-shock proteins synthesized in the cells that acquired thermotolerance were not always more than those synthesized constitutively in unstressed cells, the stressed cells synthesized heat-shock proteins (especially hsp70) preferentially over other proteins. As the level of hsp70 in the thermotolerant cells was almost the same as that in unstressed cells, the specific accumulation of hsp70 seemed not to be required for the acquisition of thermotolerance. From these findings it seemed likely that, for the induction of thermotolerance in V79 cells, hsp70 preferentially synthesized during or after the stress has an important function. Or the synthesis of heat shock proteins may not be important, and constitutively synthesized heat-shock proteins acquire a specific function during or after the stress.",
Arsenic,77704,"Mortality in a cohort of orchard workers exposed to lead arsenate pesticide spray Abstract: #During the period from 1890 to 1940, lead arsenate was the major pesticide used in apple orchards to control the coddling moth. In the Wenatchee area of Washington State, lead arsenate spray was used for longer periods and in larger quantities than in other areas of the United States. In 1938, a cohort of 1,231 people who lived in this area was selected for a study to determine the effects of exposure to lead arsenate spray and residue. This same cohort was re-examined to determine whether there was excess mortality that could be attributed to the lead arsenate exposure. Three levels of exposure (i.e., orchardist, intermediate, consumer) were defined, based upon the use of lead arsenate pesticide spray before and during the 1938 apple growing season. Age-adjusted hazard ratios for all causes of mortality were elevated for both male orchardists and male intermediates. The only significantly increased age-adjusted hazard ratio (1.94) was heart disease in male intermediates. No significantly elevated age-adjusted hazard ratios were observed for women in any exposure group. The lack of evidence that supported an increase in mortality from respiratory cancer in this cohort may have resulted from the lower cumulative concentration of arsenic exposure, the type of arsenical compound, and the small number of study subjects.",
Arsenic,2064169,"Whole-body concentrations of elements in three fish species from offshore oil platforms and natural areas in the southern California Bight, USA Abstract: There is concern that offshore oil platforms off Southern California may be contributing to environmental contaminants accumulated by marine fishes. To examine this possibility, 18 kelp bass (Paralabrax clathratus Girard, 1854), 80 kelp rockfish (Sebastes atrovirens Jordan and Gilbert, 1880), and 98 Pacific sanddab (Citharichthys sordidus Girard, 1854) were collected from five offshore oil platforms and 10 natural areas during 2005-2006 for whole-body analysis of 63 elements. Forty-two elements were excluded from statistical comparisons as they (1) consisted of major cations that were unlikely to accumulate to potentially toxic concentrations; (2) were not detected by the analytical procedures; or (3) were detected at concentrations too low to yield reliable quantitative measurements. The remaining 21 elements consisted of aluminum, arsenic, barium, cadmium, chromium, cobalt, copper, gallium, iron, lead, lithium, manganese, mercury, nickel, rubidium, selenium, strontium, tin, titanium, vanadium, and zinc. Statistical comparisons of these elements indicated that none consistently exhibited higher concentrations at oil platforms than at natural areas. However, the concentrations of copper, selenium, titanium, and vanadium in Pacific sanddab were unusual because small individuals exhibited either no differences between oil platforms and natural areas or significantly lower concentrations at oil platforms than at natural areas, whereas large individuals exhibited significantly higher concentrations at oil platforms than at natural areas.",
Arsenic,1032260,"Essential trace elements in humans. Serum arsenic concentrations in hemodialysis patients in comparison to healthy controls Abstract: Serum arsenic concentrations of persons suffering from renal failure and undergoing hemodialysis treatment (n = 85) and of healthy controls (n = 25) were determined by hydride-generation AAS technique after microwave digestion. The results were evaluated by comparing the values of both groups, considering physiological factors and individual data, as well as comorbid conditions of the hemodialysis (HD) patients. Serum arsenic levels were diminished in the patient group compared with controls (mean values 8.5 +/- 1.8 ng/mL vs 10.6 +/- 1.3 ng/mL). Furthermore, additional diseases within the hemodialysis group, particularly injuries of the central nervous system (CNS), vascular diseases, and cancer, were correlated to occasionally markedly decreased serum arsenic concentrations. It was concluded that arsenic homeostasis is disturbed by HD treatment and certain additional diseases. Desirable arsenic concentrations in the body seem to be reasonable. This consideration results in the conclusion that arsenic could play an essential role in human health. Thus, reference arsenic concentrations in different human tissues and body fluids should be established in order to recognize not only arsenic intoxication, but also arsenic deficiency. Perhaps arsenic deficiency contributes to the increased death risk of HD patients, and therefore, arsenic supplementations for patients with extremely low serum arsenic concentrations should be taken into account.",
Arsenic,734998,"Radon and risk of extrapulmonary cancers: Results of the German uranium miners' cohort study, 1960–2003 Abstract: Data from the German miners' cohort study were analysed to investigate whether radon in ambient air causes cancers other than lung cancer. The cohort includes 58,987 men who were employed for at least 6 months from 1946 to 1989 at the former Wismut uranium mining company in Eastern Germany. A total of 20,684 deaths were observed in the follow-up period from 1960 to 2003. The death rates for 24 individual cancer sites were compared with the age and calendar year-specific national death rates. Internal Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to radon in working level months (WLM). The number of deaths observed (O) for extrapulmonary cancers combined was close to that expected (E) from national rates (n=3340, O/E=1.02; 95% confidence interval (CI): 0.98-1.05). Statistically significant increases in mortality were recorded for cancers of the stomach (O/E=1.15; 95% CI: 1.06-1.25) and liver (O/E=1.26; 95% CI: 1.07-1.48), whereas significant decreases were found for cancers of the tongue, mouth, salivary gland and pharynx combined (O/E=0.80; 95% CI: 0.65-0.97) and those of the bladder (O/E=0.82; 95% CI: 0.70-0.95). A statistically significant relationship with cumulative radon exposure was observed for all extrapulmonary cancers (ERR/WLM=0.014%; 95% CI: 0.006-0.023%). Most sites showed positive exposure-response relationships, but these were insignificant or became insignificant after adjustment for potential confounders such as arsenic or dust exposure. The present data provide some evidence of increased risk of extrapulmonary cancers associated with radon, but chance and confounding cannot be ruled out.",
Arsenic,2278444,"Visible light excitable fluorescence probe and its functionalized Merrifield polymer: Selective sensing and removal of arsenate from real samples Abstract: A visible light excitable new fluorescence probe (APC) has been used for determination of arsenate in drinking water of Purbasthali in West Bengal, India. APC-functionalized Merrifield polymer is very efficient for removal of arsenate from contaminated water. APC can successfully monitor intracellular arsenate in microbes grown in arsenate affected water under a fluorescence microscope. Arsenate induced fluorescence enhancement of APC has been rationalized from intra-molecular H-bonding assisted conversion of TICT to PICT, supported by 1H NMR titration and mass spectrometry studies.",
Arsenic,656652,"Ingested arsenic, characteristics of well water consumption and risk of different histological types of lung cancer in northeastern Taiwan Abstract: Our previous study combining two arseniasis-endemic areas in Taiwan confirmed a dose-response association of lung cancer and arsenic exposure. We conducted current analysis to elucidate the dose-response relationship in lower exposure level, and to evaluate whether the association differs in different histological types. In addition, whether specific characteristics of well water consumptions increased lung cancer risk was examined in order to establish a complete risk profile for arsenic exposure. A total of 8086 residents in northeastern Taiwan were followed for 11 years and 6888 participants remained in the final analysis because 1198 residents with unknown arsenic concentration were excluded. The 178 incident lung cancers were ascertained through linkage with the national cancer registry profiles in Taiwan. All analyses were performed by Cox's proportional hazards regression models. We found a significant dose-response trend (P=0.001) of lung cancer risk associated with increasing arsenic concentration. There was no apparent increased risk at concentrations between 10 and 100 microg/L, but concentrations between 100 and 300 microg/L showed evidence of excess risk (RR 1.54, 0.97-2.46). The relative risk was 2.25 (95% CI: 1.43, 3.55) for exposure to > or = 300 microg/L when compared to <10 microg/L. The significant dose-response trends and the synergistic effect of arsenic exposure and cigarette smoking can be found in squamous and small cell carcinomas, but not in adenocarcinoma. Despite lacking statistical precision, when duration is accounted for, all levels of exposure including low concentration were in the direction of increased risk of lung cancer, and these associations tended to increase with longer durations of exposure. This study provides additional evidence linking arsenic to lung cancer, and the indications that arsenic may play a more important role in certain histological type may help with further research in carcinogenic effect of inorganic arsenic on lung cancer.",
Arsenic,1337677,"Relationship between long-term exposure to low-level arsenic in drinking water and the prevalence of abnormal blood pressure Abstract: Arsenic increases the risk and incidence of cardiovascular disease. To explore the impact of long-term exposure to low-level arsenic in drinking water on blood pressure including pulse pressure (PP) and mean arterial blood pressure (MAP), a cross-sectional study was conducted in 2010 in which the blood pressure of 405 villagers was measured, who had been drinking water with an inorganic arsenic content <50?g/L. A multivariate logistic regression model was used to estimate odds ratios and 95% confidence intervals. After adjusting for age, gender, Body Mass Index (BMI), alcohol consumption and smoking, the odds ratios showed a 1.45-fold (95%CI: 0.63-3.35) increase in the group with >30-50 years of arsenic exposure and a 2.95-fold (95%CI: 1.31-6.67) increase in the group with >50 years exposure. Furthermore, the odds ratio for prevalence of abnormal PP and MAP were 1.06 (95%CI: 0.24-4.66) and 0.87 (95%CI: 0.36-2.14) in the group with >30-50 years of exposure, and were 2.46 (95%CI: 0.87-6.97) and 3.75 (95%CI: 1.61-8.71) for the group with >50 years exposure, compared to the group with arsenic exposure ?30 years respectively. Significant trends for Hypertension (p<0.0001), PP (p<0.0001) and MAP (p=0.0016) were found. The prevalence of hypertension and abnormal PP as well as MAP is marked among a low-level arsenic exposure population, and significantly increases with the duration of arsenic exposure.",
Arsenic,1032672,"The heat shock response in HeLa cells is accompanied by elevated expression of the c-fos proto-oncogene Abstract: Several known inducers of the heat shock response (heat stress, arsenite, and heavy metals) were shown to cause a significant elevation of c-fos mRNA in HeLa cells. Heat stress resulted in a time- and temperature-dependent prolonged elevation in the level of c-fos mRNA, which was accompanied by increased translation of c-fos protein and its appearance in the nucleus. Elevated expression of c-fos during heat stress was paralleled by induction of hsp 70 mRNA, while levels of c-myc and metallothionein mRNAs declined. Treatment of HeLa cells with arsenite or heavy metals also resulted in increased levels of hsp 70, as well as c-fos mRNA. Although elevated expression of c-fos was prevented by inhibitors of RNA synthesis, analysis of relative rates of gene transcription showed that during heat stress there was a negligible change in c-fos transcription. Therefore, the enhanced expression of c-fos during the heat shock response is likely to occur primarily through posttranscriptional processes. Cycloheximide was also shown to significantly increase the c-fos mRNA level in HeLa cells. There results are consistent with the observation that these inducers of the heat shock response, as well as cycloheximide, repress protein synthesis and suggest that the increase in the level of c-fos mRNA is caused by an inhibition of protein synthesis. This supports the hypothesis that c-fos mRNA is preferentially stabilized under conditions which induce the heat shock response, perhaps by decreased synthesis of a short-lived protein which regulates c-fos mRNA turnover.",
Arsenic,2347575,"Arsenic mobility in the arsenic-contaminated Yangzonghai Lake in China Abstract: Coagulation-precipitation techniques have been used successfully in the remediation of arsenic (As) contamination, but insufficient data exist to evaluate the side effects on lake environments (especially secondary pollution). Yangzonghai Lake, a deep lake located in southwest China that was treated with flocculants after an accident resulted in As-contamination, was selected as a case study. We attempted to elucidate how As migrates and transforms in the lake based on water simulation experiments. The results were expected to facilitate evaluation of the suitability and safety of the technology when used in a natural water body. The results showed that the As that had already been precipitated into the sediment by FeCl3 would be released again into the water body due to the increasing activity of anaerobic microorganisms, thereby causing secondary pollution. This phenomenon was especially evident during summer because water temperature stratification reduced the dissolved oxygen (DO) at the sediment surface and led to anaerobic conditions, which enhanced the anaerobic activity at the bottom of the lake. In summer, the concentration of As in the water column increased with increasing depth. In contrast, during winter, the concentration of As was quite similar at all depths of the lake because the water temperature was uniform during this period. As was released from sediments to the aqueous phase in the form of trivalent As [As(III)] upon anaerobic incubation and was oxidized gradually into pentavalent As [As(V)] by the higher DO in the upper layers of the lake water. Contrary to expectation, the disturbance (turnover in the fall) did not increase, but rather decreased the As concentration in the lake, which might result in further coagulation and precipitation through intensive mixture of the unsaturated flocculants from the sediments.",
Arsenic,1240169,"Selenium antagonises the toxic effects of arsenic on mungbean (Phaseolus aureus Roxb.) plants by restricting its uptake and enhancing the antioxidative and detoxification mechanisms Abstract: The presence of arsenic (As) in the metal-contaminated soils is toxic for the crops causing their impaired growth and development. Selenium (Se) is also likely to be present along with As in the polluted soils. Se at lower concentration (Malik, JAG, S. Kaur, N. Sharma, S. Singh, I. Nayyar, H., 2012 ",
Arsenic,1353182,"Relation of arsenic supplements to dental-caries and periodontal syndrome in experimental rodents Abstract: Dietary arsenic supplements were fed to caries-susceptible rats after the molar crowns were mineralized almost completely, during the mineralization of the crowns, or throughout and after development. No influence on caries activity was observed. Dietary supplements of arsenic to weanling rice rats tended to cause small increases in the severity of the periodontal syndrome.",
Arsenic,1030950,"Rate of malignant tumor mortality among coal burning power plant workers occupationally exposed to arsenic Abstract: The mortality pattern was retrospectively analyzed among the workers of a power plant A (exposure group) combusting coal with high arsenic levels and among the workers of power plants B, C and D (control group), where arsenic concentrations in coal were by one order of magnitude lower. The exposed group consisted of 88 and the control group of 159 male subjects deceased over the period of the last 15--18 years. The rate of tumor mortality among the exposed subjects who died during their productive age was 38% (in the control group 23%), among those died after 60 it was 51% (in the controls 43%). This increase in the tumor mortality rates was not statistically significant. What was, however, statistically proved to be significant is the fact that malignancy-caused deaths in the exposed group occurred in younger age categories and after a statistically shorter exposure time (in both cases p &lt; 0.05). Combusted coal is known to contain a variety of biologically active microelements, but the amount of arsenic alone (950--1500 g/1 tonne of coal) most probably fully justifies the suspected link between the tumor incidence and the overexposure to arsenic.",
Arsenic,656668,"Arsenite causes down-regulation of Akt and c-Fos, cell cycle dysfunction and apoptosis in glutathione-deficient cells Abstract: Arsenic is a well-known environmental toxicant but the mechanism by which it causes cytotoxicity is poorly understood. Arsenite induces apoptosis in glutathione (GSH)-deficient GCS-2 cells by causing cell cycle dysfunction and down-regulating critical signaling pathways. This study was designed to examine the effect of arsenite on redox-sensitive phosphatidylinositol 3-kinase (PI3K)/Akt, a signaling pathway involved in cell survival and growth, and transcription factor, activating protein-1 (AP-1). Arsenite significantly diminished Akt and c-Fos levels and caused accelerated degradation of these proteins by ubiquitnation. Arsenite also induced cell cycle arrest and apoptosis. The cell cycle arrest involved the down-regulation of cyclin A2, cyclin D1, cyclin E, cyclin dependent kinases (CDK) 2, CDK4, and CDK6. Apoptosis involved down-regulation of anti-apoptotic proteins Bcl-2, Bcl-xL, survivin, and inhibitor of apoptosis protein (IAP) and up-regulation of pro-apoptotic protein Bax. Taken together, our results suggest that a possible mechanism of arsenite-induced toxicity under low/no GSH conditions, is to negatively regulate GCS-2 cell proliferation by attenuating Akt and AP-1 by ubiquitination and causing cell cycle dysfunction and apoptosis.",
Arsenic,2064195,"Evaluation of chronic arsenic poisoning due to consumption of contaminated ground water in West Bengal, India Abstract: <strong>BACKGROUND: </strong>Chronic arsenic poisoning is an important public health problem and most notable in West Bengal and Bangladesh. In this study different systemic manifestations in chronic arsenic poisoning were evaluated.<br /><br /><strong>METHODS: </strong>A nonrandomized, controlled, cross-sectional, observational study was carried out in Arsenic Clinic, Institute of Postgraduate Medical Education and Research, Kolkata, West Bengal, over a period of 1 year 4 months. Seventy-three cases diagnosed clinically, consuming water containing arsenic ?50 ?g/L and having hair and nail arsenic level >0.6 ?g/L, were included. Special investigations included routine parameters and organ-specific tests. Arsenic levels in the drinking water, hair, and nail were measured in all. Twenty-five nonsmoker healthy controls were evaluated.<br /><br /><strong>RESULTS: </strong>Murshidabad and districts adjacent to Kolkata, West Bengal, were mostly affected. Middle-aged males were the common sufferers. Skin involvement was the commonest manifestation (100%), followed by hepatomegaly [23 (31.5%)] with or without transaminitis [7 (9.58%)]/portal hypertension [9 (12.33%)]. Restrictive abnormality in spirometry [11 (15.06%)], bronchiectasis [4 (5.47%)], interstitial fibrosis [2 (2.73%)], bronchogenic carcinoma [2 (2.73%)], oromucosal plaque [7 (9.58%)], nail hypertrophy [10 (13.69%)], alopecia [8 (10.95%)], neuropathy [5 (6.84%)], and Electrocardiography abnormalities [5 (6.84%)] were also observed.<br /><br /><strong>CONCLUSIONS: </strong>Mucocutaneous and nail lesions, hepatomegaly, and restrictive change in spirometry were the common and significant findings. Other manifestations were characteristic but insignificant.",
Arsenic,2337106,"Impact of microorganisms on arsenic biogeochemistry: A review Abstract: Microorganisms are abundant in many surface and near-surface geochemical environments. They interact with arsenic through a variety of mechanisms, including sorption, mobilisation, precipitation and redox and methylation transformation; sometimes, this is to their benefit, while other times it is to their detriment, substantially affecting the fate and transport of arsenic in the environment. Here, an attempt was made to review the current state of knowledge concerning microbial influences on arsenic transformation and retention processes at the water-solid interface with the goal to elucidate the ability of microorganisms to react with arsenic, and to quantify the role of microorganisms in the biogeochemical arsenic cycle. Such knowledge is indispensable for comprehensive understanding arsenic behaviour in the environment and support accurate assessment of the threat of arsenic contamination to human and environmental health, as well as for the development of novel technologies for arsenic bioremediation.",
Arsenic,1015740,"Arsenic variation in two basins of lake dianchi Abstract: The spatial variation of arsenic, including arsenic speciation changes under the influence of water quality parameters in lake Dianchi, China was investigated. The water quality parameters were found to differ between the two basins of the lake (Caohai vs. Waihai), consistent with the eutrophic status. Arsenic in Caohai was greater than that in Waihai, with average values as 9.45 and 6.68 ?g L(-1), respectively. Expect redox potential, correlation between various water quality parameters and arsenic forms were found, supporting the hypothesis that arsenic partition in suspended particulates in Lake Dianchi was driven mainly by biota factor.",
Arsenic,1509338,Inhibition of nucleotide excision repair by arsenic Abstract: ,
Arsenic,656798,"Proteomic analyses of arsenic-induced cell transformation with SELDI-TOF ProteinChip technology Abstract: In this study, we demonstrated that low levels (1.5 microM) of arsenite induces B[a]P-treated lung cell transformation. We then used a proteomic approach to identify protein expression by ProteinChips, which could potentially be important for transformation induced by this toxic metal. Most of the protein peaks in cell extracts of all samples, including the control, B[a]P-treated, and B[a]P + As-treated cells are identical. However, surface-enhanced laser desorption/ionization time of flight (SELDI-TOF) analysis with Cu-ProteinChips and WCX-ProteinChips revealed several dramatically different protein peaks that appeared in lung cells after being transformed by a treatment of 1.5 microM arsenite for 12 weeks. SAX2 ProteinChip also identified a prominent protein peak that was preferentially expressed in control cells. Interestingly, by using a SAX2 chip, we were able to detect several protein peaks that increased their expression in lung epithelial cells (LEC) treated with only B[a]P. Identification and characterization of these proteins may reveal the molecular basis of As-induced cell transformation and provide insight into the mechanisms by which arsenic induces carcinogenesis.",
Arsenic,1016934,"The influence of low-power laser energy on red blood cell metabolism and deformability Abstract: The aim of this study was to test the hypothesis that exposure of red blood cells (RBC) to low-power laser energy can modulate their metabolism and deformability. The effects of exposure to a He-Ne (lambda=632.8 nm), GaAlAs (lambda=780 nm) and GaAs (lambda=904 nm) lasers have been examined. Red cells diluted to a hematocrit of 45% were incubated in a humidified atmosphere of 95% air and 5% CO(2) at 37 degrees C, and exposed to three different laser beams held 5 cm from the target area to yield a spot surface area of 2 cm(2). Three red cell suspensions belonging to the experimental groups were treated with each laser beam by 5, 15 and 30 minutes, respectively. The temperature was constant during the exposure's time. Three control suspensions of RBC were kept for the same time as sham-irradiated groups. The erythrocyte elongation index (EEI) was evaluated using a Rheodyn SSD (Myrene, Roetgen, Germany). The enzyme activities of glucose-6-phosphate dehydrogenase (G-6-PD), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were assayed in each sample spectrophotometrically. Adenosine triphosphate (ATP) and diphosphoglicerate (2,3-DPG) levels were also assessed. No statistical differences were observed in the erythrocyte elongation index at shear stresses of 0.30, 0.60, 1.20, 3.00, 6.00, 12.00, 30.00 and 60.00 Pa after being irradiated for 5 and 15 minutes as compared to not irradiated ones. At 30.00 and 60.00 Pa a decrease (p&lt;0.03 and p&lt;0.05, respectively) in EEI has been observed after 30 min exposure to all three wavelengths of laser light when compared to the control. The antioxidant enzyme activities showed no significant changes following 5, 15 and 30 min of irradiation by all three laser wavelengths laser tested. Similarly, erythrocyte organic phosphate levels (ATP and 2,3-DPG) showed no significant changes following treatment by laser radiation. This study revealed that the low-power laser at 632.8, 780 and 904 nm wavelengths have little biological effects on red blood cells in vitro.",
Arsenic,1070358,"Arsenic and chromium in drinking water promote tumorigenesis in a mouse colitis-associated colorectal cancer model and the potential mechanism is ROS-mediated Wnt/?-catenin signaling pathway Abstract: Exposure to carcinogenic metals, such as trivalent arsenic [As(III)] and hexavalent chromium [Cr(VI)], through drinking water is a major global public health problem and is associated with various cancers. However, the mechanism of their carcinogenicity remains unclear. In this study, we used azoxymethane/dextran sodium sulfate (AOM/DSS)-induced mouse colitis-associated colorectal cancer model to investigate their tumorigenesis. Our results demonstrate that exposure to As(III) or Cr(VI), alone or in combination, together with AOM/DSS pretreatment has a promotion effect, increasing the colorectal tumor incidence, multiplicity, size, and grade, as well as cell inflammatory response. Two-dimensional differential gel electrophoresis coupled with mass spectrometry revealed that As(III) or Cr(VI) treatment alone significantly changed the density of proteins. The expression of ?-catenin and phospho-GSK was increased by treatment of carcinogenic metals alone. Concomitantly, the expression of NADPH oxidase1 (NOX1) and the level of 8-OHdG were also increased by treatment of carcinogenic metals alone. Antioxidant enzymes, such as superoxide dismutase (SOD) and catalase, were decreased. Similarly, in an in vitro system, exposure of CRL-1807 to carcinogenic metals increased reactive oxygen species (ROS) generation, the expression of ?-catenin, phospho-GSK, and NOX1. Inhibition of ROS generation by addition of SOD or catalase inhibited ?-catenin expression and activity. Our study provides a new animal model to study the carcinogenicity of As(III) and Cr(VI) and suggests that As(III) and Cr(VI) promote colorectal cancer tumorigenesis, at least partly, through ROS-mediated Wnt/?-catenin signaling pathway.",
Arsenic,1350602,"[Study of the relation between chronic exposure to natural arsenic in drinking water and some cancers in Auvergne] Abstract: The International Agency for Research on Cancer has classified inorganic arsenic as carcinogenic for humans (group 1). The geologic features of Auvergne result in the presence of natural arsenic in its water. In 2001, more than 140,000 people were served by water networks in which arsenic concentrations exceeded 10??g/L (maximum contaminant level in effect since 2003). The objective of this study was to look for a link between chronic exposure to low-level doses of arsenic in drinking water and the occurrence of some cancers. This ecological study was conducted among the population living in three districts of Auvergne. The exposure and health indicators were collected at the municipality level. The cancer sites selected for study were the skin (melanoma), kidneys, bladder and urinary tract, and lungs. A relation between cancer and exposure to arsenic in drinking water was sought by a spatial analysis applying a Poisson regression model. The results showed a significant relation between the incidence of lung cancer in men and the presence of arsenic in water intended for human consumption. No association was observed among women for any of the cancers studied, and no other associations were observed among men.",
Arsenic,1352577,Dietary selenium fortification: a potential solution to chronic arsenic toxicity Abstract: ,
Arsenic,1936033,"Novel identification of lipid-soluble arsenic compounds using chemical derivatisations in conjunction with RP-HPLC-ICPMS/ESMS Abstract: The identification of molecular structures of arsenolipid is pivotal for its toxicological assessment and in understanding the arsenic cycling in the environment. However, analysis of these compounds in lipid matrix is an ongoing challenge. So far only few arsenolipids have been reported, such as arsenic fatty acids (AsFAs) and arsenic hydrocarbons (AsHCs). By means of RP-HPLC-ICPMS/ESMS, we investigated Capelin oil (Mallotus villosus) for possible new species of arsenolipid. Twelve arsenolipids were identified in the fish oil including three AsFAs and seven AsHCs. Among the AsHCs, four of them identified with protonotated molecular masses 305, 331, 347 and 359 have not been reported before. In addition, the compounds with molecular formulae C20H44AsO+ and C24H44AsO+ found in low concentrations showed chromatographic properties and MS data consistent with cationic trimethylarsenio fatty alcohols. Derivatisation by acetylation and thiolation coupled with accurate mass spectrometry was successfully used to establish the occurrence of this new class of arsenolipids as cationic trimethylarsenio fatty alcohols (TMAsFOH).",
Arsenic,2064173,The effect of arsenic on pigment composition and photosynthesis in Hydrilla verticillata Abstract: ,
Arsenic,1704068,"Arsenic remediation field study using a sulfate reduction and zero-valent iron PRB Abstract: Toxic and carcinogenic effects of arsenic in drinking water continue to impact people throughout the world and arsenic remains common in groundwater at cleanup sites and in areas with natural sources. Advances in groundwater remediation are needed to attain the low concentrations that are protective of human health and the environment. In this article, we present the successful use of a permeable reactive barrier (PRB) utilizing sulfate reduction coupled with zero-valent iron (ZVI) to remediate the leading edge of a dissolved arsenic plume in a wetland area near Tacoma, Washington. A commercially available product (EHC-M®, Adventus Americas Inc., Freeport, Illinois) that contains ZVI, organic carbon substrate, and sulfate was injected into a reducing, low-seepage-velocity aquifer elevated in dissolved arsenic and iron from a nearby, slag-containing landfill. Removal effectiveness was strongly correlated with sulfate concentration, and was coincident with temporary redox potential (Eh) reductions, consistent with arsenic removal by iron sulfide precipitation. The PRB demonstrates that induced sulfate reduction and ZVI are capable of attaining a regulatory limit of 5 µg/L total arsenic, capturing of 97% of the arsenic entering the PRB, and sustaining decreased arsenic concentrations for approximately 2 years, suggesting that the technology is appropriate for consideration at other sites with similar hydrogeochemical conditions. The results indicate the importance of delivery and longevity of minimum sulfate concentrations and of maintaining sufficient dissolved organic carbon and/or microscale ZVI to precipitate FeS, a precursor phase to arsenic-bearing pyrite that may provide a stable, long-term sink for arsenic.",
Arsenic,1255505,"Assessment of heavy metals in water samples and tissues of edible fish species from Awassa and Koka Rift Valley Lakes, Ethiopia Abstract: The Ethiopian Rift Valley Lakes host populations of edible fish species including Oreochromis niloticus, Labeobarbus intermedius and Clarias gariepinus, which are harvested also in other tropical countries. We investigated the occurrence of six heavy metals in tissues of these fish species as well as in the waters of Lake Koka and Lake Awassa. Both lakes are affected by industrial effluents in their catchments, making them ideal study sites. Mercury concentrations were very low in the water samples, but concentrations in the fish samples were relatively high, suggesting a particularly high bioaccumulation tendency as compared with the other investigated metals. Mercury was preferentially accumulated in the fish liver or muscle. It was the only metal with species-specific accumulation with highest levels found in the predatory species L. intermedius. Lower mercury concentrations in O. niloticus could be attributed to the lower trophic level, whereas mercury values in the predatory C. gariepinus were unexpectedly low. This probably relates to the high growth rate of this species resulting in biodilution of mercury. Accumulation of lead, selenium, chromium, arsenic and cadmium did not differ between species, indicating that these elements are not biomagnified in the food chain. Values of cadmium, selenium and arsenic were highest in fish livers, while lead and chromium levels were highest in the gills, which could be related to the uptake pathway. A significant impact of the industrial discharges on the occurrence of metals in the lakes could not be detected, and the respective concentrations in fish do not pose a public health hazard.",
Arsenic,2278783,"Bone resorption is suppressed immediately after the third and fourth days of multiday cycling but persistently increased following overnight recovery Abstract: Previous studies suggest that seasoned cyclists may incur a low bone mineral density. This study investigated the effect of multiday cycling on bone turnover. Ten male cyclists completed 4 consecutive days of cycling for 3 h·day(-1). Sweat calcium excretion during exercise and serum calcium, cortisol, bone formation marker (bone alkaline phosphotase (bone-ALP)), bone resorptive marker (C-terminal telopeptide of type I collagen (?-CTX)), and parathyroid hormone concentration were measured before and immediately postexercise each day. Serum ?-CTX concentration increased from pre- to postcycling on days 1 and 2 (p = 0.01) (day 1: 0.31 ± 0.14 to 0.60 ± 0.4 ng·mL(-1); day 2: 0.58 ± 0.26 to 0.87 ± 0.42 ng·mL(-1)), while serum bone-ALP concentration remained unchanged. Conversely, on days 3 and 4 both serum ?-CTX (day 3: 0.60 ± 0.26 to 0.43 ± 0.26 ng·mL(-1), p &lt; 0.05; day 4: 0.63 ± 0.21 to 0.43 ± 0.22 ng·mL(-1), p &lt; 0.001) and bone-ALP (p &lt; 0.01) response to exercise was suppressed. Interestingly, calcium lost to sweat and postexercise serum cortisol concentration were also significantly lower on days 3 and 4 than on day 1 (p &lt; 0.05). However, both serum ?-CTX (102%-124%) and bone-ALP (25%-29%) remained persistently elevated after 21 h of overnight recovery on all successive days compared with day 1 pre-exercise, where the percentage increase was greater for ?-CTX (p &lt; 0.05). Bone resorption, immediately following prolonged cycling, is acutely reduced by the third and fourth consecutive days and is coincident to reduced sweat calcium excretion and cortisol concentration. However, multiday cycling imposes a persistent increase in bone resorption following overnight recovery.",
Arsenic,1354303,"EFFECTS OF LEAD AND ARSENIC ON THE FORMATION OF 5-BETA-H STEROIDS Abstract: The effects of lead (7439921) and arsenic (7440382) on the biosynthesis of 5beta-H-steroids were studied. Rats were given 25 micromoles of lead (as lead acetate) per 100 grams daily for 3 days, or 2 micromoles of arsenic per 100 grams daily for 5 days. Three days after the final lead treatment and 7 days after the final arsenic treatment, liver homogenates were analyzed for steroid 5-beta-reductase, 3-alpha and 3-beta-hydroxysteroid-dehydrogenase activities, and beta-D-glucuronidase activity. After lead treatment, delta-4-androstene-3,17-dione-5-beta-reductase increased significantly and progesterone-5beta-reductase increased slightly. No changes occured in adrenosterone, 17alpha-hydroxy-progesterone, or delta-4-pregnen-20-beta-ol-3-one-5-beta-reductase. Following arsenic treatment, delta-4-androstene-13,17-dione, testosterone, progesterone, and 17-alpha-hydroxy progesterone 5-beta reductase activities increased significantly. Adrenosterone increased slightly, but delta4-pregnen-20-beta-ol-3-one was unchanged. Lead treatment increased 3-beta-hydroxysteroid-dehydrogenase activity, but did not significantly affect 3-alpha-hydroxysteroid-dehydrogenase activity; the opposite effect occurred following arsenic treatment. Beta-D-glucuronidase was unaffected by lead or arsenic. The authors conclude that certain 5-beta-H steroids may be enhanced by lead or arsenic treatment. They suggest that these steroids affect the formation of delta-aminolevulinic-acid (ALA) synthetase, and are a factor in increasing ALA after lead or arsenic treatment.",
Arsenic,1508629,"Application of solid phase extraction on multiwalled carbon nanotubes of some heavy metal ions to analysis of skin whitening cosmetics using ICP-AES Abstract: A novel and highly sensitive method for the determination of some heavy metals in skin whitening cosmetics creams using multiwalled carbon nanotubes MWCNTs as solid phase extraction sorbent for the preconcentration of these heavy metals prior to their determination by inductively coupled plasma atomic emission spectrometry is described. Different practical parameters have been thoroughly investigated and the optimum experimental conditions were employed. The developed method was then applied for the determination of arsenic, bismuth, cadmium, mercury, lead and titanium in samples of skin whitening cosmetics. The detection limits under these conditions for As, Bi, Cd, Pb, Hg and Ti were 2.4, 4.08, 0.3, 2.1, 1.8, and 1.8 ng·mL-1, respectively. The relative standard deviations (RSDs) were found to be less than 2.0%. For validation, a certified reference material of NIST SRM 1570a spinach leaves was analyzed and the determined values were in good agreement with the certified values. The recoveries for spiked samples were found to be in the range of 89.6-104.4%.",
Arsenic,710940,"Genetic polymorphisms in glutathione S-transferase (GST) superfamily and arsenic metabolism in residents of the Red River Delta, Vietnam Abstract: To elucidate the role of genetic factors in arsenic metabolism, we investigated associations of genetic polymorphisms in the members of glutathione S-transferase (GST) superfamily with the arsenic concentrations in hair and urine, and urinary arsenic profile in residents in the Red River Delta, Vietnam. Genotyping was conducted for GST omega1 (GSTO1) Ala140Asp, Glu155del, Glu208Lys, Thr217Asn, and Ala236Val, GST omega2 (GSTO2) Asn142Asp, GST pi1 (GSTP1) Ile105Val, GST mu1 (GSTM1) wild/null, and GST theta1 (GSTT1) wild/null. There were no mutation alleles for GSTO1 Glu208Lys, Thr217Asn, and Ala236Val in this population. GSTO1 Glu155del hetero type showed higher urinary concentration of As(V) than the wild homo type. Higher percentage of DMA(V) in urine of GSTM1 wild type was observed compared with that of the null type. Strong correlations between GSTP1 Ile105Val and arsenic exposure level and profile were observed in this study. Especially, heterozygote of GSTP1 Ile105Val had a higher metabolic capacity from inorganic arsenic to monomethyl arsenic, while the opposite trend was observed for ability of metabolism from As(V) to As(III). Furthermore, other factors including sex, age, body mass index, arsenic level in drinking water, and genotypes of As (+3 oxidation state) methyltransferase (AS3MT) were also significantly co-associated with arsenic level and profile in the Vietnamese. To our knowledge, this is the first study indicating the associations of genetic factors of GST superfamily with arsenic metabolism in a Vietnamese population.",
Arsenic,711038,"Structure-function alteration of hemoglobin in arsenicosis patients: a probable pathway to exert toxicity Abstract: Chronic arsenicosis, a major public health concern in India and Bangladesh, is mainly caused by ingestion of arsenic (As) contaminated ground water. Although this problem has been studied extensively, the mechanism of toxicity remains unknown. This paper investigates the process of trivalent arsenicals binding to hemoglobin (Hb) in chronic arsenicosis patients and consequent modification in the structure-function activity of Hb. In this work peroxidase activity, thermal denaturation profile, oxygen releasing capacity and hydrodynamic diameter have been evaluated for the Hb collected from subjects suffering with chronic arsenicosis. Increased peroxidative activity suggests altered oxidative status of Hb in the diseased state. The thermal denaturation profile indicates the Hb molecule to be more susceptible to unfolding in the pathologic state. The enhanced oxygen releasing capacity and significant reduction in hydrodynamic diameter of Hb is also observed in the diseased condition, suggesting conformational alterations in the Hb molecule. Finally, trivalent arsenic is found to bind with freshly isolated Hb from arsenicosis patients, binding affinity constant being 0.256??M(-1) . The binding is positively cooperative with a Hill coefficient of +2.961 and isosbestic points at specific wavelengths. Thus, our work explores the structure-function property of Hb in chronic arsenicosis subjects and reveals that the molecule is modified in such a way that comparatively weak binding with oxygen and strong binding with arsenic occur simultaneously. This association may play a crucial role in exerting the pathway for arsenic toxicity. Copyright © 2011 John Wiley &amp; Sons, Ltd.",
Arsenic,2149159,"A ?-Glutamyl Cyclotransferase Protects Arabidopsis Plants from Heavy Metal Toxicity by Recycling Glutamate to Maintain Glutathione Homeostasis Abstract: Plants detoxify toxic metals through a GSH-dependent pathway. GSH homeostasis is maintained by the ?-glutamyl cycle, which involves GSH synthesis and degradation and the recycling of component amino acids. The enzyme ?-glutamyl cyclotransferase (GGCT) is involved in Glu recycling, but the gene(s) encoding GGCT has not been identified in plants. Here, we report that an Arabidopsis thaliana protein with a cation transport regulator-like domain, hereafter referred to as GGCT2;1, functions as ?-glutamyl cyclotransferase. Heterologous expression of GGCT2;1 in Saccharomyces cerevisiae produced phenotypes that were consistent with decreased GSH content attributable to either GSH degradation or the diversion of ?-glutamyl peptides to produce 5-oxoproline (5-OP). 5-OP levels were further increased by the addition of arsenite and GSH to the medium, indicating that GGCT2;1 participates in the cellular response to arsenic (As) via GSH degradation. Recombinant GGCT2;1 converted both GSH and ?-glutamyl Ala to 5-OP in vitro. GGCT2;1 transcripts were upregulated in As-treated Arabidopsis, and ggct2;1 knockout mutants were more tolerant to As and cadmium than the wild type. Overexpression of GGCT2;1 in Arabidopsis resulted in the accumulation of 5-OP. Under As toxicity, the overexpression lines showed minimal changes in de novo Glu synthesis, while the ggct2;1 mutant increased nitrogen assimilation by severalfold, resulting in a very low As/N ratio in tissue. Thus, our results suggest that GGCT2;1 ensures sufficient GSH turnover during abiotic stress by recycling Glu.",
Arsenic,1354422,Esterification equilibrium constants of arsonic and arsinic acids Abstract: ,
Arsenic,1018584,"The toxicity of organoarsenic-based warfare agents: in vitro and in vivo studies Abstract: The four arsenic-containing chemical warfare agents (CWA) Adamsite (technical, 10-chloro-9-10-dihydrophenarsazine), Clark 1 (Diphenyl arsine chloride), Clark 2 (Diphenyl arsine cyanide), and Lewisite (2-chloro-ethenyl dichloro arsine) were evaluated toxicologically using an in vitro and an in vivo model. The CWA were tested in vitro, using human leucocytes, in order to evaluate their effects on cell proliferation and cell cycle kinetics assayed by flow cytometry. The concentration for total inhibition of cell proliferation for the CWAs ranged from 0.3 micrograms/mL (Lewisite) to 15 micrograms/mL (Clark 1). The results showed no differences in cell proliferation between the different stages of the S-phase either at no-effect or at effect concentrations when samples treated with the CWAs were compared with untreated controls. As2O5 was used as a reference, and the arsenic concentration required for total inhibition of the cell proliferation was 1.7 mg/mL. A lower arsenic concentration, 0.83 micrograms/mL, showed a decreasing proliferation ration in the different parts of the S-phase with Searly and Slate having the highest and lowest ratios, respectively. In addition, there was a positive correlation between the unlabeled S-phase cell ratio and the arsenic concentration, indicating cessation of DNA-synthesis. Conclusively, the examined CWAs exerts a toxicity more potent than arsenic, with respect to cell proliferation. This might indicate that the toxicity of these arsenic-containing CWAs only to a minor extent can be explained by their arsenic content. Because of their relatively good water solubility and ability to easily degrade to arsenic acid, organo-arsenics, e.g., Lewisite, pose less of an environmental threat than organo-arsenics that are sparingly soluble and chemically persistent, like Adamsite. The four CWAs were also tested in vivo in a dietary exposure study, using juvenile three-spined stickleback (Gasterosteus aculeatus L.) as test organism, with measurement of EROD-activity and studies of liver morphology. The results from the in vivo study indicated small effects, suggesting that a 10-week period of dietary exposure at tested dose levels (1 and 100 ng/ml) affects juvenile three-spined stickleback only to a minor extent.",
Arsenic,627200,"Arsenic in drinking water and bladder cancer mortality in the United States: An analysis based on 133 U.S. counties and 30 years of observation Abstract: This study analyzes the relationship between arsenic exposure through drinking water and bladder cancer mortality. The county-specific white male bladder cancer mortality data (1950-1979) and county-specific groundwater arsenic concentration data were obtained for 133 U.S. counties known to be exclusively dependent on groundwater for their public drinking water supply. No arsenic-related increase in bladder cancer mortality was found over the exposure range of 3 to 60 microg/L using stratified analysis and regression analyses (both unweighted and weighted by county population and using both mean and median arsenic concentrations). These results, which provide a direct estimate of arsenic-related cancer risk for U.S. residents, exclude the National Research Council's 2001 risk estimate that was based on Southwest Taiwan data and required adjusting for differences between the body mass and water consumption rates of U.S. and Taiwanese residents.",
Arsenic,2039823,"Water quality assessment and analysis of spatial patterns and temporal trends Abstract: This study investigated relationships of a water quality index (WQI) with multiple water quality variables (WQVs), explored variability in water quality over time and space, and established linear and non-linear models predictive of WQI from raw WQVs. Data were processed using Spearman's rank correlation analysis, multiple linear regression, and artificial neural network modeling. Correlation analysis indicated that from a temporal perspective, the WQI, temperature, and zinc, arsenic, chemical oxygen demand, sodium, and dissolved oxygen concentrations increased, whereas turbidity and suspended solids, total solids, nitrate nitrogen (NO3-N), and biochemical oxygen demand concentrations decreased with year. From a spatial perspective, an increase with distance of the sampling station from the headwater was exhibited by 10 WQVs: magnesium, calcium, dissolved solids, electrical conductivity, temperature, NO3-N, arsenic, chloride, potassium, and sodium. At the same time, the WQI; Escherichia coli bacteria counts; and suspended solids, total solids, and dissolved oxygen concentrations decreased with distance from the headwater. Lastly, regression and artificial neural network models with high prediction powers (81.2% and 91.4%, respectively) were developed and are discussed.",
Arsenic,1018756,"Time-dependent porphyric response in mice subchronically exposed to arsenic Abstract: 1. A time-course study was carried out in mice subchronically exposed to As III (as sodium arsenite) or As V (as sodium arsenate), via drinking water, relating the pattern of urinary porphyrin excretion to the renal and hepatic enzyme activities of porphobilinogen deaminase (PBGD), uroporphyrinogen III synthetase (URO III-S), uroporphyrinogen decarboxylase (URO-D) and coproporphyrinogen oxidase (COPRO-O), as well as to the hepatic porphyrin accumulation in the treated animals. 2. A time-dependent, wave-like porphyric response was found in mice exposed to As V, and the increases seen in total urinary porphyrins (at 3 weeks of exposure) corresponded to an increased activity of PBGD and Uro III-S in liver. 3. Significant decreases in renal URO-D and hepatic and renal COPRO-O activities were found in treated mice; these inhibitions were more pronounced in animals exposed to As III. 4. The combination of these enzymic effects may explain the time-dependent porphyric response of mice subchronically exposed to As. Finally, the relative magnitudes of URO-D and COPRO-O inhibitions may determine the pattern of porphyrin concentration observed in urine and tissues. 5. The decrease in renal URO-D activity may help to explain the inversion in the coproporphyrin/uroporphyrin ratio previously reported in humans chronically exposed to As; however, there were differences between the urinary porphyrin profiles found in both species. The possible reasons for the similarities and differences are briefly discussed.",
Arsenic,1519173,"Profiling the ionome of rice and its use in discriminating geographical origins at the regional scale, China Abstract: Element profile was investigated for their use to trace the geographical origin of rice (Oryza sativa L.) samples. The concentrations of 13 elements (calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P), boron (B), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), arsenic (As), selenium (Se), molybdenum (Mo), and cadmium (Cd)) were determined in the rice samples by inductively coupled plasma optical emission and mass spectrometry. Most of the essential elements for human health in rice were within normal ranges except for Mo and Se. Mo concentrations were twice as high as those in rice from Vietnam and Spain. Meanwhile, Se concentrations were three times lower in the whole province compared to the Chinese average level of 0.088 mg/kg. About 12% of the rice samples failed the Chinese national food safety standard of 0.2 mg/kg for Cd. Combined with the multi-elemental profile in rice, the principal component analysis (PCA), discriminant function analysis (DFA) and Fibonacci index analysis (FIA) were applied to discriminate geographical origins of the samples. Results indicated that the FIA method could achieve a more effective geographical origin classification compared with PCA and DFA, due to its efficiency in making the grouping even when the elemental variability was so high that PCA and DFA showed little discriminatory power. Furthermore, some elements were identified as the most powerful indicators of geographical origin: Ca, Ni, Fe and Cd. This suggests that the newly established methodology of FIA based on the ionome profile can be applied to determine the geographical origin of rice.",
Arsenic,1597385,Spectrofluorimetric Determination of Arsenic(III) Using Dansylated Peptide Abstract: ,
Arsenic,2337276,"Distribution, origin, and transformation of metal and metalloid pollution in vegetable fields, irrigation water, and aerosols near a Pb-Zn mine Abstract: Pollution of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) in vegetable fields was investigated near a Pb-Zn mine that has been exploited for over 50 years without a tailing reservoir. A total of 205 water, soil, and aerosol samples were taken and quantified by combined chemical, spectrometric, and mineral analytical methods. The pollution origins were identified by Pb isotopes and the pathways of transformation and transport of the elements and minerals was studied. The data showed that the vegetable fields were seriously polluted by As, Cd, and Pb. Some concentrations in the samples were beyond the regulatory levels and not suitable for agricultural activities. This study revealed that: (1) particulate matter is a major pollution source and an important carrier of mineral particles and pollutants; (2) the elements from the polluted water and soils were strongly correlated with each other; (3) Pb isotope ratios from the samples show that Pb minerals were the major pollution sources in the nearby vegetable fields, and the aerosols were the main carrier of mining pollution; (4) the alkaline, rich-carbonate, and wet conditions in this area promoted the weathering and transformation of galena into the secondary minerals, anglesite and cerussite, which are significant evidence of such processes; (5) the soil and the aerosols are a recycled secondary pollution source for each other when being re-suspended with wind.Highlights• Mining activities generated heavy metal pollution in fields around a Pb-Zn mine• The elements from water and soils are strongly correlated• Anglesite and cerussite are evidence of galena transformation into secondary minerals• Particulate matter is an important transport carrier of pollution.",
Arsenic,1020264,"How acute promyelocytic leukaemia revived arsenic Abstract: Despite its many therapeutic qualities, arsenic trioxide has been more commonly remembered as Madame Bovary's poison than as an anticancer drug. The ability of arsenic trioxide to treat acute promyelocytic leukaemia has radically changed this view, providing new insights into the pathogenesis of this malignancy and raising hopes that arsenicals might be useful in treating other cancers.",
Arsenic,2343463,"Effect of arsenic on nitrification of simulated mining water Abstract: Mining and mineral processing of gold-bearing ores often release arsenic to the environment. Ammonium is released when N-based explosives or cyanide are used. Nitrification of simulated As-rich mining waters was investigated in batch bioassays using nitrifying cultures enriched in a fluidized-bed reactor (FBR). Nitrification was maintained at 100mg AsTOT/L. In batch assays, ammonium was totally oxidized by the FBR enrichment in 48h. As(III) oxidation to As(V) occurred during the first 3h attenuating arsenic toxicity to nitrification. At 150 and 200mg AsTOT/L, nitrification was inhibited by 25%. Candidatus Nitrospira defluvii and other nitrifying species mainly colonized the FBR. In conclusion, the FBR enriched cultures of municipal activated sludge origins tolerated high As concentrations making nitrification a potent process for mining water treatment.",
Arsenic,2278396,"Determination of arsenic (III) by differential pulse polarography in the waters of Camarones area, Chile Abstract: As (III) was determined by differential pulse polarography (DPP) in 1 mol L-1 HCl as supporting electrolyte. For quantification, the -0.35 V peak (versus Ag/AgCl) was chosen. The obtained detection and quantification limits were 2.7 (3 SD) and 8.9 (10 SD) mu g L-1 respectively. <br> <br>The method was used for the determination of As (III) on surface water samples from Camarones River, located in Camarones area, province of Arica, Chile (this area's water contain high levels of salinity). The results indicate that the proposed methodology is a suitable analytical alternative for As determination in natural waters with high levels of dissolved salts, as the waters of Camarones River. The method is not time consuming, nor tedious no prior treatment of the sample is required. The results show that As (III) concentrations in waters of Camarones River are about 10 times higher than the guide values established by WHO for water intended for human consumption.",
Arsenic,1378247,"Relation Of Urinary Metabolites Of Inorganic Arsenic With Transforming Growth Factor Alpha Concentration In Bladder Urothelial Cells From A Population Environmentally Exposed To Inorganic Arsenic Abstract: Inorganic arsenic (iAs) is a well established human carcinogen and its exposure is associated with a variety of cancers including those of skin,lung,and bladder. High expression of transforming growth factor alpha (TGFalpha) has associated with local relapses in early stages of urinary bladder cancer. Due to the extent and character of adverse effects associated with iAs exposures are at least in part determined by the rate of formation and composition of iAs metabolites (MMA, DMA), this study examines the relationship between TGFalpha concentration in exfoliated bladder urothelial cells (BUC) separated from urine and urinary arsenic species among 78 residents (18-51-year-old) in both high and low iAs-exposed subjects of an endemic region of central Mexico. Urinary arsenic species, including trivalent methylated metabolites were measured by hydride generation atomic absorption spectrometry method. The concentration of TGFalpha in BUC was measured by using an ELISA assay. The participants on this study are from areas exposed to different concentrations of iAs in drinking water (6?378 ppb). Results show a statistically significant positive correlation between TGFalpha concentration in BUC and each of the six arsenic species present in urine. However, urinary arsenicals in pentavalency (iAsV+MMAV+DMAV) were better associated with TGFalpha concentration (p=0.005 vs. 0.021) than the trivalency (iAsIII+MMAIII+DMAIII). People from areas with high arsenic concentration had a significantly higher TGFalpha concentration in BUC than people of areas with low arsenic exposure (67.5 vs. 34.6 pg/mg protein;p=0.020. These results indicate that in iAs-endemic areas, the concentration of TGFalpha in exfoliated BUC may serve as a marker of the exposure to iAs in drinking water and as an indicator of adverse epithelial health effects associated with this exposure.",
Arsenic,1347943,"Endothelial cell apoptosis is accelerated by inorganic iron and heat via an oxygen radical dependent mechanism Abstract: <strong>BACKGROUND: </strong>Iron participates in diverse pathologic processes by way of the Fenton reaction, which catalyzes the formation of reactive oxygen species (ROS). To test the hypothesis that this reaction accelerates apoptosis, we used human umbilical vein endothelial cells (HUVECs) as surrogates for the microvasculature in vivo.<br /><br /><strong>METHODS: </strong>HUVECs were loaded with Fe [III](ferric chloride and ferric ammonium citrate) with 8-hydroxyquinoline as carrier and were then challenged with two stimuli of the heat shock response, authentic heat or sodium arsenite. Iron dependence was tested with two chelators, membrane-impermeable deferoxamine and membrane-permeable o-phenanthroline. The role of ROS was assessed with superoxide dismutase, catalase, and the reporter compound dichlorofluorescein diacetate. The mechanism of cell death was assessed with three complementary techniques, Annexin V/propidium iodide labeling, the TUNEL stain, and electron microscopy.<br /><br /><strong>RESULTS: </strong>Iron-loaded HUVECs executed apoptosis after a heat shock stimulus. Iron-catalyzed formation of ROS appeared to be a critical mechanism, because both chelation of iron and enzymatic detoxification of ROS attenuated this apoptosis.<br /><br /><strong>CONCLUSIONS: </strong>Inorganic iron, in concert with chemical and physical inducers of the heat shock response, may trigger apoptosis. The accumulation of iron in injured tissue may thereby predispose to accelerated apoptosis and account, in part, for poor wound healing and organ failure.",
Arsenic,1018674,"Increased rate of apoptosis correlates with hepatocellular proliferation in Fischer-344 rats following long-term exposure to a mixture of groundwater contaminants Abstract: Apoptosis was evaluated in the livers of Fischer-344 rats following observations of increased hepatocellular proliferation from exposures, at low parts per million (ppm) levels, to a drinking water mixture of 7 groundwater contaminants during a 6-mo time-course study. The 7 chemicals used are among the most frequently detected contaminants associated with hazardous waste sites: arsenic, benzene, chloroform, chromium, lead, phenol, and trichloroethylene. Significant increases in 5-bromo-2'-deoxyuridine hepatocellular labeling were present in a unique pattern surrounding large hepatic veins (0.5-2.0 mm). This did not appear to be a regenerative response due to cytotoxicity, as assessed by the absence of increased plasma enzyme activity and the absence of hepatocellular lesions. Immunohistochemical staining for apoptosis, using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method showed patterns of labeling in treated animals that directly correlated to areas of increased hepatocyte proliferation. Apoptotic activity was maximum at the 1-mo exposure time point, whereas proliferating hepatocytes reached a maximum rate at the 10-day time point. This may have been triggered as a compensatory response to the increased cell proliferation or as a protective response to remove cells with altered DNA due to chemical mixture exposure. The principal findings of this paper are that (a) apoptosis directly correlated with changes in cell proliferation: (b) observed effects were produced by repeated exposures to a relatively low-level chemical mixture; and (c) the TUNEL method detected apoptotic cells at very early and late stages, potentially increasing the observable time period for apoptosis.",
Arsenic,1019945,"German Environmental Survey 1998 (GerES III): Environmental pollutants in the urine of the German population Abstract: The German Environmental Survey (GerES) is a cross-sectional probability study to determine the exposure of the general population to environmental contaminants. The study was repeated for the third time in 1998 (GerES III). Again, a stratified random procedure was used to select the study population taking into account the parameters gender, age, community size and place of residence (West- or East-Germany). A total of 4822 persons between 18 and 69 years of age from 120 localities participated in GerES III. Human biomonitoring comprised the determination of arsenic, cadmium, mercury, metabolites of polycyclic aromatic hydrocarbons (PAH), pentachlorophenol (PCP), other chlorophenols, precious metals (gold, platinum, iridium), nicotine, and cotinine in urine.",
Arsenic,1935429,"Impact of anthropogenic and natural processes on the evolution of groundwater chemistry in a rapidly urbanized coastal area, South China Abstract: The moving of manufacturing industry from developed countries to Dongguan, China, promoted the semi-urbanization and rural industrialization in this area. It is urgent to acquire the impact of the enhanced anthropogenic pressure on the evolution of groundwater chemistry in this area. The objectives, in this study, were to understand the evolution of groundwater chemistry in Dongguan area based on the comparison of hydrochemical data variations and land use changes during the urbanization, to distinguish the impact of natural processes and anthropogenic activities on the groundwater chemistry by using principal components analysis (PCA) and hierarchical cluster analysis (HCA), and to discuss the origins of trace elements in groundwater. Eighteen physico-chemical parameters were investigated at 73 groundwater sites during July 2006. By analyzing the hydrochemical data, it shows that lateral flow from rivers and agricultural irrigation are the mechanisms controlling the groundwater chemistry in the river network area where the cation exchange of Na(+) in sediments taken up by the exchanger Ca(2+) occurs. Seawater intrusion is the mechanism controlling the groundwater chemistry in the coast area where the cation exchange of Ca(2+) in sediments taken up by the exchanger Na(+) occurs. The ion exchange reaction for fissured aquifer is weak in the study area. In addition, the comparison of hydrochemical data between in 2006 and in 1980 shows that anthropogenic activities such as excessive application of agricultural fertilizers, inappropriate emissions of domestic sewage and excessive emissions of SO2 are responsible for the occurrences of groundwater with NO3(-), SO4(2-) and Mg(2+) types. Four principal components (PCs) were extracted from PCA, which explain 80.86% of the total parameters in water chemistry: PC1, the seawater intrusion and As contamination; PC2, the water-rock interaction, surface water recharge and acidic precipitation; PC3, heavy metal pollution from industry; and PC4, agricultural pollution and sewage intrusion. Four clusters were generated from HCA: cluster 1 is mainly influenced by the industrialization; cluster 2 is mainly affected by the water-rock interaction and the irrigation and lateral flow of river water; cluster 3 is mainly influenced by the seawater intrusion; and cluster 4 is mainly influenced by the sewage intrusion and agricultural pollution. The results show that both natural processes such as seawater intrusion, water-rock interaction and lateral flow of river water and anthropogenic activities such as industrialization, sewage intrusion and agricultural pollution are the two major factors for the evolution of groundwater chemistry in Dongguan area.",
Arsenic,2278539,"Effect of residue combinations on plant uptake of nutrients and potentially toxic elements Abstract: The aim of the plant pot experiment was to evaluate potential environmental impacts of combined industrial residues to be used as soil fertilisers by analysing i) element availability in fly ash and biosolids mixed with soil both individual and in combination, ii) changes in element phytoavailability in soil fertilised with these materials and iii) impact of the fertilisers on plant growth and element uptake. <br> <br>Plant pot experiments were carried out, using soil to which fresh residue mixtures had been added. The results showed that element availability did not correlate with plant growth in the fertilised soil with. The largest concentrations of K (3534 mg/l), Mg (184 mg/l), P (1.8 mg/l), S (760 mg/l), Cu (0.39 mg/l) and Zn (0.58 mg/l) in soil pore water were found in the soil mixture with biosolids and MSWI fly ashes; however plants did not grow at all in mixtures containing the latter, most likely due to the high concentration of chlorides (82 g/kg in the leachate) in this ash. It is known that high salinity of soil can reduce germination by e.g. limiting water absorption by the seeds. The concentrations of As, Cd and Pb in grown plants were negligible in most of the soils and were below the instrument detection limit values. <br> <br>The proportions of biofuel fly ash and biosolids can be adjusted in order to balance the amount and availability of macronutrients, while the possible increase of potentially toxic elements in biomass is negligible seeing as the plant uptake of such elements was low.",
Arsenic,1339168,"An arsenic fluorescent compound as a novel probe to study arsenic-binding proteins Abstract: Arsenic-binding proteins are under continuous research. Their identification and the elucidation of arsenic/protein interaction mechanisms are important because the biological effects of these complexes may be related not only to arsenic but also to the arsenic/protein structure. Although many proteins bearing a CXXC motif have been found to bind arsenic in vivo, new tools are necessary to identify new arsenic targets and allow research on protein/arsenic complexes. In this work, we analyzed the performance of the fluorescent compound APAO-FITC (synthesized from p-aminophenylarsenoxide, APAO, and fluorescein isothiocyanate, FITC) in arsenic/protein binding assays using thioredoxin 1 (Trx) as an arsenic-binding protein model. The Trx-APAO-FITC complex was studied through different spectroscopic techniques involving UV-Vis, fluorescence, atomic absorption, infrared and circular dichroism. Our results show that APAO-FITC binds efficiently and specifically to the Trx binding site, labeling the protein fluorescently, without altering its structure and activity. In summary, we were able to study a protein/arsenic complex model, using APAO-FITC as a labeling probe. The use of APAO-FITC in the identification of different protein and cell targets, as well as in in vivo biodistribution studies, conformational studies of arsenic-binding proteins, and studies for the design of drug delivery systems for arsenic anti-cancer therapies, is highly promising.",
Arsenic,2064220,Arsenic levels in chicken Abstract: ,
Arsenic,1027950,"Sodium arsenite alters cell cycle and MTHFR, MT1/2, and c-Myc protein levels in MCF-7 cells Abstract: There is limited available information on the effects of arsenic on enzymes participating in the folate cycle. Therefore, our aim was to evaluate the effects of sodium arsenite on the protein levels of methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) and its further relationship with the expression MT1/2 and c-myc in MCF-7 cells. Arsenite treatment (0-10 microM) for 4 h decreased MTHFR levels in a concentration-dependent fashion without significant effects on DHFR. The effects on MTHFR were observed at arsenite concentrations not significantly affecting cell viability. We also observed an increase in S-phase recruitment at all concentrations probed. Lower concentrations (&lt;5 microM) induced cell proliferation, showing a high proportion of BrdU-stained cells, indicating a higher DNA synthesis rate. However, higher concentrations (&gt; or =5 microM) or longer treatment periods induced apoptosis. Arsenite also induced dose-dependent increases in MT1/2 and c-Myc protein levels. The levels of MTHFR were inversely correlated to MT1/2 and c-Myc overexpression and increased S-phase recruitment. Our findings indicate that breast epithelial cells are responsive to arsenite and suggest that exposure may pose a risk for breast cancer. The reductions in MTHFR protein levels contribute to understand the mechanisms underlying the induction of genes influencing growth regulation, such as c-myc and MT1/2. However, further research is needed to ascertain if the effects here reported following short-time and high-dose exposure are relevant for human populations chronically exposed to low arsenic concentrations.",
Arsenic,1372837,"Acute And Chronic Exposure Of Monomethylarsonous Acid To Human Bladder Cells Induces Cyclooxygenase-2 Abstract: Studies from our laboratory have shown that human bladder cells (UROtsa), a target of arsenic-induced cancer, can biotransform arsenite to monomethylarsonous acid [MMA(III)], which is more cytotoxic and capable of transforming the UROtsa cells following long-term, low-level exposure. UROtsa cells treated with 50 nM MMA(III) for 24 weeks had a significant induction of genes associated with inflammation, such as tumor necrosis factor alpha (TNF-alpha)-induced proteins 2 and 3. Cyclooxygenase-2 (COX-2), a product of TNF-alpha signal transduction, causes hyperplasia in bladder cells and is considered a key biomarker in bladder cancer. To investigate the role of inflammation in MMA(III)-induced transformation, UROtsa cells were treated with 50 nM MMA(III) for 12, 24, or 36 weeks and analyzed by western blot for COX-2 induction. COX-2 induction was noted following chronic MMA(III) exposure and this induction increased with duration of exposure, suggesting that COX-2 plays a role in MMA(III)-induced transformation. Acute exposure studies found MMA(III) treatment (10, 50, and 100 nM, 4 h) induced COX-2 in UROtsa cells with the lowest doses (10 and 50 nM) causing the strongest induction. Studies are continuing to determine if COX-2 induction by MMA(III) is associated with activation of NF- gammaB, a pro-inflammatory transcription factor. These studies have the promise of correlating MMA(III) exposure to an inflammatory response that may, in part, provide insight into the mechanism of arsenic- induced bladder cancer.",
Arsenic,1017954,"Natural and man-made health hazards in rural Slovakia Abstract: <strong>CONTEXT: </strong>There is little information on health situation of the people of rural Slovak Republic. The rural environment is often a mixture of natural and man-made hazards, which under some conditions, might turn to be a health risk to humans.<br /><br /><strong>PURPOSE: </strong>The aim of this study was to compare two regions of the Slovak Republic, two different hazards (natural and man-made), two different methods of health outcome measurement (routine statistics and individual diary based data).<br /><br /><strong>METHODS: </strong>Ecological study design with focus on cancer incidence analysis was employed in case of natural hazard analysis. Standardized incidence ratios (SIR) were calculated and are presented in paper. Observational study design was employed to study rural gardening practices and their impact on health.<br /><br /><strong>FINDINGS: </strong>Statistically significant differences in SIR were found in rural areas of Spis-Gemer Region (SGR) among males for lip, oral cavity and larynx (1.60, CI 95% 1.12-2.34), respiratory (1.25, CI 95% 1.01-1.55) and digestive organ cancers (1.22, CI 95% 1.01-1.47); hematopoetic cancers are significantly elevated among males in rural areas as well (1.58, CI 95% 1.05-2.39). Pesticide use (83.1% of gardeners use pesticides) without any protective equipment is still widespread among gardeners in rural Slovak Republic (16.9%). The produced fruits and vegetables are substantial part of total fruit and vegetable consumption (51% in summer and 42.7% in winter season) increasing the risk of exposure to pesticides.<br /><br /><strong>CONCLUSION: </strong>Our study shows that on ecological level, mortality and morbidity statistics could be used to assess human health status in linkage to broad exposure measures (urban-rural); on dose response level (arsenic in soil) this method lacks sensitivity. Health survey and diary method on the other hand are useful tools in analysis of rural health especially with respect to man-made hazards.",
Arsenic,1070448,"Novel Plasmids and Resistance Phenotypes in Yersinia pestis: Unique Plasmid Inventory of Strain Java 9 Mediates High Levels of Arsenic Resistance Abstract: Growing evidence suggests that the plasmid repertoire of Yersinia pestis is not restricted to the three classical virulence plasmids. The Java 9 strain of Y. pestis is a biovar Orientalis isolate obtained from a rat in Indonesia. Although it lacks the Y. pestis-specific plasmid pMT, which encodes the F1 capsule, it retains virulence in mouse and non-human primate animal models. While comparing diverse Y. pestis strains using subtractive hybridization, we identified sequences in Java 9 that were homologous to a Y. enterocolitica strain carrying the transposon Tn2502, which is known to encode arsenic resistance. Here we demonstrate that Java 9 exhibits high levels of arsenic and arsenite resistance mediated by a novel promiscuous class II transposon, named Tn2503. Arsenic resistance was self-transmissible from Java 9 to other Y. pestis strains via conjugation. Genomic analysis of the atypical plasmid inventory of Java 9 identified pCD and pPCP plasmids of atypical size and two previously uncharacterized cryptic plasmids. Unlike the Tn2502-mediated arsenic resistance encoded on the Y. enterocolitica virulence plasmid; the resistance loci in Java 9 are found on all four indigenous plasmids, including the two novel cryptic plasmids. This unique mobilome introduces more than 105 genes into the species gene pool. The majority of these are encoded by the two entirely novel self-transmissible plasmids, which show partial homology and synteny to other enterics. In contrast to the reductive evolution in Y. pestis, this study underlines the major impact of a dynamic mobilome and lateral acquisition in the genome evolution of the plague bacterium.",
Arsenic,1339428,"Exposure to arsenic in urban and rural areas and effects on thyroid hormones Abstract: <strong>CONTEXT: </strong>Arsenic is a ubiquitous element present in urban air as a pollutant, and it may interfere with thyroid hormones.<br /><br /><strong>OBJECTIVE: </strong>To evaluate the association between the personal exposure to arsenic and levels of TSH, fT4, fT3, and Tg in urban and rural workers.<br /><br /><strong>MATERIALS AND METHODS: </strong>Total urinary arsenic and thyroid markers were obtained from 108 non-smoking traffic policemen and 77 subjects working as roadmen in a rural area. Fifty subjects were monitored to evaluate airborne exposure to arsenic.<br /><br /><strong>RESULTS: </strong>The mean value of exposure to arsenic was 2.9 µg/m(3) in traffic policemen, while the mean value was less than 0.1 µg/m(3) in roadmen. The mean values of urinary arsenic (10.4 ?g/g creatinine vs. 5.2 ?g/g creatinine; p = 0.000), TSH (1.6 µlU/ml vs. 1.3 µlU/ml; p = 0.006), fT3 (3.5 pg/ml vs. 3.7 pg/ml; p = 0.000), fT4 (1.2 ng/dl vs. 1.3 ng/dl; p = 0.000) and Tg (42.8 ng/ml vs. 36.1 ng/ml; p = 0.04) were significantly different between traffic policemen and roadmen. In traffic policemen, urinary arsenic and arsenic in the air were correlated to the airborne arsenic and TSH values, respectively. Urinary arsenic was correlated to TSH, Tg, fT3, and fT4 values. The multiple linear regression models showed the following associations: i) among urinary arsenic, arsenic in the air and job title; ii) among TSH, fT3, Tg and urinary arsenic; and iii) between fT4 and both urinary arsenic and alcohol intake.<br /><br /><strong>CONCLUSION: </strong>These results provide information about the relationship between exposure to arsenic and thyroid markers and may be useful for other categories of outdoor workers who are similarly exposed.",
Arsenic,1519034,"One-Pot Synthesis of Water-Swellable Mg-Al Layered Double Hydroxides and Graphene Oxide Nanocomposites for Efficient Removal of As(V) from Aqueous Solutions Abstract: In this article, we reported a remarkably simple and efficient method for the preparation of layered double hydroxides and graphene oxide (LDHs/GO) nanocomposites with varying GO amounts via a hydrothermal process. The graphene nature in the resulting LDHs/GO nanocomposites was confirmed by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, and X-ray photoelectron spectroscopy (XPS). The LDHs/GO nanocomposites exhibited swelling behavior in water and forming a gel. The adsorption performance of the LDHs/GO nanocomposites was evaluated for the removal of arsenate (As(V)) from aqueous solutions, and the results showed that the ratio of GO to LDHs in the nanocomposites significantly affected the adsorption capacity. Higher and lower amounts of GO in LDHs/GO nanocomposites showed lower adsorption capacity of As(V). A maximum adsorption capacity of 183.11 mg/g (2.44 mmol/g) was achieved on the LDHs/GO containing 6.0% GO due to the higher BET surface area than other samples. Owing to their high uptake capability of As(V), water-swellable LDHs/GO nanocomposites are expected to have potential applications as adsorbents for As(V) polluted water cleanup.",
Arsenic,628316,"In vivo effects of arsenite on meiosis, preimplantation development, and apoptosis in the mouse Abstract: Inorganic arsenic, an environmental contaminant, produces a variety of stress responses in mammalian cells, including metabolic abnormalities accompanied by growth inhibition and carcinogenesis. Much of the toxicity of arsenic is known to stem from its uncoupling effects on mitochondria. Because previously we had shown that mitochondrial dysfunction can disrupt oocyte and embryo development, we investigated effects of arsenite on meiotic progression and early embryo development in mice. Six-week-old CD-1 mice were treated with 0 (solvent as control), 8 mg/kg (a dose previously established in mice as the maternal no-observed-adverse-effect level), and 16 mg/kg doses of sodium arsenite every 2 days for a total of seven i.p. injections ver a period of 14 days. The incidence of meiotic anomalies, characterized by spindle disruption and/or chromosomal misalignment, was significantly increased in arsenite-treated groups (25% after 8 mg/kg and 62.5% after 16 mg/kg), compared to normal metaphase II in control oocytes. Further, arsenite treatment significantly decreased cleavage rates of zygotes at 24 h, morula formation at 72 h, and development to blastocysts at 96 h in a dose-dependent manner. The total cell number in developed blastocysts did not differ significantly between the 8 mg/kg arsenite treatment and control groups, but was significantly reduced in the 16 mg/kg arsenite treatment group. Moreover, the percentage of apoptotic nuclei was significantly increased in blastocysts following 16 mg/kg arsenite treatment. These data suggest that arsenite causes meiotic aberrations, which may contribute to decreased cleavage and preimplantation development, as well as increased apoptosis.",
Arsenic,1250959,"Fungal biodegradation of CCA-treated wood and removal of its metal components Abstract: In the present study, 5 isolates of brown-rot fungi were used for fungal bioprocessing (FB) of chromated copper arsenate (CCA)-treated wood wastes: Antrodia vaillantii SEL8501, Fomitopsis palustris TYP0507 and TYP6137, and Crustoderma sp. KUC8065 and KUC8611. The isolates showed notable capacity for the degradation of treated wood and removal of CCA components via the American Wood Protection Association soil block test. Among them, Crustoderma sp. KUC8611 effectively decayed the treated wood, causing a mass loss of up to 60%. F. palustris caused extensive leaching of CrO(3) of up to 79% and As(2)O(5) of up to 87%, but only moderate leaching of CuO of up to 50%. This high capacity for removal of CrO(3) and As(2)O(5) showed a strong logarithmic relationship with the amount of oxalic acid produced in the decayed wood. The majority of metals removed from treated wood during the decay process were deposited in the soil and feeder strip. Further investigation will be required to establish the capability of selected fungi for FB of full-sized lumber treated with CCA.",
Arsenic,67672,"Uptake, distribution, and metabolism of trivalent arsenic in the pregnant mouse Abstract: To investigate the distribution of trivalent arsenic (arsenite) in the pregnant rodent, CD-1 mice were dosed with sodium arsenite by ip injection or by gavage on gestation d 18 (copulation plug day = d 1). Doses were 8 (ip) or 25 (po) mg/kg, and samples of maternal blood, liver, and kidneys, as well as fetuses and pooled placentas, were analyzed for total arsenic at intervals of up to 24 h. Fetal tissue was also analyzed for relative proportions of inorganic arsenic and methylated metabolites. Arsenic uptake was significantly greater in the injected mice and their fetuses (as a proportion of the administered dose), with levels highest at 10 min to 4 h in maternal tissues and 24 h in fetuses. Peak maternal arsenic levels (as microgram/g or microgram/ml) ranged from 2.36 (blood) to 26.15 (liver) for the ip injected and 1.25 (blood) to 17.64 (liver) for the gavaged treatment group. The rate of arsenic elimination from maternal samples was not significantly influenced by administration route, with first-order elimination rate constants (k) of 0.215 and 0.234 h-1 for the po and ip dosed mice, respectively. Fetal tissue arsenic peaks were 2.10 and 0.77 micrograms/g for the ip and po treatment groups, respectively. The proportion of methylated arsenic in fetuses increased to 79% in the ip treatment group and 88% in the po group by 24 h. Such results show that much of the arsenic reaching the mouse fetus has been methylated to less toxic metabolites. They also confirm that assumptions made regarding hazard to the fetus must reflect the likelihood that a portion of any maternal dose of inorganic arsenite reaching a fetus may have been methylated, and they support previous findings that arsenite is toxic to the conceptus at lower doses when given by injection than by gavage.",
Arsenic,1349156,Concurrent expression of heme oxygenase-1 and p53 in human retinal pigment epithelial cell line Abstract: ,
Arsenic,1597310,"Expression in Arabidopsis and cellular localization reveal involvement of rice NRAMP, OsNRAMP1, in arsenic transport and tolerance Abstract: Irrigation of paddy fields to arsenic (As) containing groundwater leads to As accumulation in rice grains and causes serious health risk to the people worldwide. To reduce As intake via consumption of contaminated rice grain, identification of the mechanisms for As accumulation and detoxification in rice is a prerequisite. Herein, we report involvement of a member of rice NRAMP (Natural Resistance-Associated Macrophage Protein) transporter, OsNRAMP1, in As, in addition to cadmium (Cd), accumulation through expression in yeast and Arabidopsis. Expression of OsNRAMP1 in yeast mutant (fet3fet4) rescued iron (Fe) uptake and exhibited enhanced accumulation of arsenic and Cd. Expression of OsNRAMP1 in Arabidopsis provided tolerance with enhanced As and Cd accumulation in root and shoot. Cellular localization revealed that OsNRAMP1 resides on plasma membrane of endodermis and pericycle cells and may assist in xylem loading for root to shoot mobilization. This is the first report demonstrating role of NRAMP in xylem mediated loading and enhanced accumulation of As and Cd in plants. We propose that genetic modification of OsNRAMP1 in rice might be helpful in developing rice with low As and Cd content in grain and minimize the risk of food chain contamination to these toxic metals.",
Arsenic,2278264,"Biogeochemical implications of the ubiquitous colonization of marine habitats and redox gradients by Marinobacter species Abstract: The Mannobacter genus comprises widespread marine bacteria, found in localities as diverse as the deep ocean, coastal seawater and sediment, hydrothermal settings, oceanic basalt, sea-ice, sand, solar salterns, and oil fields. Terrestrial sources include saline soil and wine-barrel-decalcification wastewater. The genus was designated in 1992 for the Gram-negative, hydrocarbon-degrading bacterium Marinobacter hydrocarbonoclasticus. Since then, a further 31 type strains have been designated. Nonetheless, the metabolic range of many Mannobacter species remains largely unexplored. Most species have been classified as aerobic heterotrophs, and assessed for limited anaerobic pathways (fermentation or nitrate reduction), whereas studies of low-temperature hydrothermal sediments, basalt at oceanic spreading centers, and phytoplankton have identified species that possess a respiratory repertoire with significant biogeochemical implications. Notable physiological traits include nitrate-dependent Fe(II)-oxidation, arsenic and fumarate redox cycling, and Mn(II) oxidation. There is also evidence for Fe(III) reduction, and metal(loid) detoxification. Considering the ubiquity and metabolic capabilities of the genus, Mannobacter species may perform an important and underestimated role in the biogeochemical cycling of organics and metals in varied marine habitats, and spanning aerobic-to-anoxic redox gradients.",
Arsenic,627397,"Arsenite transport by mammalian aquaglyceroporins AQP7 and AQP9 Abstract: Much is known about the transport of arsenite and antimonite into microbes, but the identities of mammalian transport proteins are unknown. The Saccharomyces cerevisiae FPS1 gene encodes a membrane protein homologous to the bacterial aquaglyceroporin GlpF and to mammalian aquaglyceroporins AQP7 and AQP9. Fps1p mediates glycerol uptake and glycerol efflux in response to hypoosmotic shock. Fps1p has been shown to facilitate uptake of the metalloids arsenite and antimonite, and the Escherichia coli homolog, GlpF, facilitates the uptake and sensitivity to metalloid salts. In this study, the ability of mammalian aquaglyceroporins AQP7 and AQP9 to substitute for the yeast Fps1p was examined. The fps1Delta strain of S. cerevisiae exhibits increased tolerance to arsenite and antimonite compared to a wild-type strain. Introduction of a plasmid containing AQP9 reverses the metalloid tolerance of the deletion strain. AQP7 was not expressed in yeast. The fps1Delta cells exhibit reduced transport of (73)As(III) or (125)Sb(III), but uptake is enhanced by expression of AQP9. Xenopus laevis oocytes microinjected with either AQP7 or AQP9 cRNA exhibited increased transport of (73)As(III). These results suggest that AQP9 and AQP7 may be a major routes of arsenite uptake into mammalian cells, an observation potentially of large importance for understanding the action of arsenite as a human toxin and carcinogen, as well as its efficacy as a chemotherapeutic agent for acute promyelocytic leukemia.",
Arsenic,1597338,"Cadmium in blood of Tunisian men and risk of bladder cancer: Interactions with arsenic exposure and smoking Abstract: Prior investigations identified an association between low-level blood arsenic (As) and bladder cancer risk among Tunisian men but questions remain regarding confounding by cadmium (Cd), a well-established bladder carcinogen. A case-control study of Tunisian men was re-examined to assess the levels of cadmium in blood and reparse the association between the simultaneous exposure to these metals and bladder cancer risk. Levels of blood Cd were significantly twice higher among cases than in controls (P?<?0.05) and were positively correlated with smoking and age. Additionally, analysis of metal levels among non-smokers according to the region of residence showed very high blood Cd and As levels for the coastal regions of Sfax and central Tunisia. After controlling for potential confounders, for low blood As levels (<0.67 ?g/L), the OR for blood Cd was 4.10 (95 % CI 1.64-10.81), while for higher levels (>0.67 ?g/L), it was reduced to 2.10 (CI, 1.06-4.17). Adjustment for Cd exposure did not alter the risk associated to As exposure. This study is the first to report the relationship between Cd exposure and risk of bladder cancer occurrence in interaction with smoking and As exposure. Smoking is shown to be the main exposure source to Cd in the Tunisian population but also environmental pollution seems to be responsible of Cd exposure among non-smokers. Exposure assessment studies encompassing a wider population are needed.",
Arsenic,2064176,"Autoantibodies against cytoskeletal neuronal proteins in sera of arsenic-exposed subjects correlate with neurological symptoms Abstract: This descriptive study correlates the presence of serum autoantibodies to five neuronal cytoskeletal proteins with neurologic deficits in subjects exposed to arsenic (As). Arsenic exposure remains a serious problem in many countries producing skin lesions and hair loss. More serious manifestations include: liver and kidney damage, encepha- lopathy, peripheral neuropathy, gangrene of extremities, and cancer. Bangladesh rep- resents one of the countries where high percentage of population is exposed to As through highly contaminated drinking groundwater. Autoantibodies were determined against the following proteins: neurofilament triplet proteins (NFP), microtubule asso- ciated protein-2 (MAP2), and microtubule associated protein tau (tau). Sera were obtained from 14 subjects in the severely affected village of Mianpur, Charghat Thana, Rajshahi. Individuals were further divided into group A with objective complaints of organic neurologic damage and group B without neurologic deficits manifestations and eight healthy controls from Rajshahi city. High levels of autoantibodies were detected in five subjects against low molecular weight neurofilaments (NFL) and in two subjects against high molecular weight neurofilament (NFH). Two subjects displayed significantly increased levels of MAP-2 autoantibodies and two others high levels of tau autoantibodies. All elevated autoantibodies were detected in group A subjects who were diagnosed with neurological disorders ranging from sleep disorders to paralysis. The results demonstrate a good correlation between neurologic defects in As-exposed subjects and presence of sera neuronal autoantibodies to cytoskeletal proteins.",
Arsenic,1355169,ARSENIC DETERMINATION BY ATOMIC-ABSORPTION SPECTROSCOPY Abstract: ,
Arsenic,2064151,Genetic variations of MT2A gene are associated with arsenic levels in biological samples of individuals occupationally exposed to arsenic Abstract: ,
Arsenic,1024621,"A critical role for IkappaB kinase beta in metallothionein-1 expression and protection against arsenic toxicity Abstract: Arsenic is a widespread environmental toxic agent that has been shown to cause diverse tissue and cell damage and at the same time to be an effective anti-cancer therapeutic agent. The objective of this study is to explore the signaling mechanisms involved in arsenic toxicity. We show that the IkappaB kinase beta (IKKbeta) plays a crucial role in protecting cells from arsenic toxicity. Ikkbeta(-)(/)(-) mouse 3T3 fibroblasts have decreased expression of antioxidant genes, such as metallothionein 1 (Mt1). In contrast to wild type and IKKbeta-reconstituted Ikkbeta(-)(/)(-) cells, IKKbeta-null cells display a marked increase in arsenic-induced reactive oxygen species (ROS) accumulation, which leads to activation of the MKK4-c-Jun NH(2)-terminal kinase (JNK) pathway, c-Jun phosphorylation, and apoptosis. Pretreatment with the antioxidant N-acetylcysteine (NAC) and expression of MT1 in the Ikkbeta(-)(/)(-) cells prevented JNK activation; moreover, NAC pretreatment, MT1 expression, MKK4 ablation, and JNK inhibition all protected cells from death induced by arsenic. Our data show that two signaling pathways appear to be important for modulating arsenic toxicity. First, the IKK-NF-kappaB pathway is crucial for maintaining cellular metallothionein-1 levels to counteract ROS accumulation, and second, when this pathway fails, excessive ROS leads to activation of the MKK4-JNK pathway, resulting in apoptosis.",
Arsenic,1016986,"Assessment of arsenic level in the hair of the nonoccupational Egyptian population: pilot study Abstract: Arsenic level of hair samples of apparently healthy Egyptian was measured by means of hydride atomic absorption spectrophotometery. It ranged between 0.04 and 1.04 mg As/kg hair, about 55% of the analysed hair samples were within the range of allowable values (0.08-0.25 mg As/kg hair), but 45% were not. There were no considerable sex-related differences (0.303 and 0.292 mg As/kg hair for males and females, respectively). Different educational levels did not influence it either, when the effect of the age had been excluded. Children and adolescents proved to be more susceptible to arsenic as their mean levels (0.353 microg/g), and were significantly higher than those in the adults (0.233 microg/g). Smoking and some dietary habits had an important role in the elevation of arsenic levels among the nonoccupational Egyptian population: 60% of smokers and 66.7% of indoor passive smokers had arsenic levels &gt;0.25 mg As/kg hair. Arsenic levels were also dependent on the kind of smoking, as hair arsenic of the subject smoking molasses tobacco was found to be significantly higher than that of cigarette smokers (0.459 and 0.209 mg As/kg hair, respectively). The frequency of meat and fish consumption per week was also found to be positively, significantly correlated with arsenic levels. On the other hand, the frequency of consumption of fruits, fresh and cooked vegetables, milk and milk products per week beneficially influenced the arsenic level of the hair samples examined. Arsenic content of the consumed water in Egypt was 0.001 mg/l, which is below the maximum drinking water level allowed by World Health Organisation (WHO). Therefore, the arsenic content of domestic tap water hardly contributed to the arsenic exposure of the Egyptian population in the regions of the study. It is likely that exposure routes by smoking, fish and animal protein consumption are the principal cause of arsenic accumulation in the general Egyptian population.",
Arsenic,1252625,"Determination of selenium and arsenic in animal tissues with platform furnace atomic absorption spectrometry and deuterium background correction Abstract: Determination of selenium and arsenic in animal tissues is disturbed mainly by spectral interferences, uncorrectable with the dueterium arc. These interferences are produced by the calcium and magnesium phosphates always present in these matrixes. In animal tissue solution this disturbance may be avoided by addition of 20 micrograms of Ni (nitrate) for a 10 microliter sample. A lower amount of nickel does not allow a correct development of analyte absorbance signals whereas an excess induces a loss of sensitivity for the two elements studied. Measurement of peak-height proved to be most suitable, integrated absorbance being partially influenced by the matrix. The slope constants of working curves obtained with different animal matrixes are very close and direct calibration becomes possible. This was confirmed by analysis of several reference materials.",
Arsenic,1936128,Immobilization of As and Pb in contaminated sediments using waste resources Abstract: ,
Arsenic,628509,"Biological gradient between long-term arsenic exposure and carotid atherosclerosis Abstract: BACKGROUND: Long-term exposure to ingested arsenic has been documented to induce peripheral vascular disease, ischemic heart disease, and cerebral infarction in a dose-response relationship. This study further examined the biological gradient between ingested inorganic arsenic and carotid atherosclerosis. METHODS AND RESULTS: We studied 199 male and 264 female adult residents from the southwestern area of endemic arseniasis in Taiwan. The extent of carotid atherosclerosis was assessed by duplex ultrasonography. Diabetes mellitus was determined by oral glucose tolerance test, hypertension by mercury sphygmomanometers, and serum lipid profiles by autoanalyzers. Information regarding the consumption of high-arsenic artesian well water, cigarette smoking, and alcohol consumption was obtained through standardized questionnaire interviews. Logistic regression analysis was used to estimate the odds ratio and its 95% CI of carotid atherosclerosis for various risk factors. Three indices of long-term exposure to ingested arsenic, including the duration of consuming artesian well water, the average arsenic concentration in consumed artesian well water, and cumulative arsenic exposure, were all significantly associated with prevalence of carotid atherosclerosis in a dose-response relationship. The biological gradient remained significant after adjustment for age, sex, hypertension, diabetes mellitus, cigarette smoking, alcohol consumption, waist-to-hip ratio, and serum levels of total cholesterol and LDL cholesterol. The multivariate-adjusted odds ratio was 3.1 (95% CI 1.3 to 7.4) for those who had a cumulative arsenic exposure of > or =20 mg/L-years compared with those without exposure to arsenic from drinking artesian well water. CONCLUSIONS: Carotid atherosclerosis is associated with ingested inorganic arsenic, showing a significant biological gradient.",
Arsenic,656914,"Arsenic exposure transforms human epithelial stem/progenitor cells into a cancer stem-like phenotype Abstract: BACKGROUND: Inorganic arsenic is a ubiquitous environmental carcinogen affecting millions of people worldwide. Evolving theory predicts that normal stem cells (NSCs) are transformed into cancer stem cells (CSCs) that then drive oncogenesis. In humans, arsenic is carcinogenic in the urogenital system (UGS), including the bladder and potentially the prostate, whereas in mice arsenic induces multi-organ UGS cancers, indicating that UGS NSCs may represent targets for carcino-genic initiation. However, proof of emergence of CSCs induced by arsenic in a stem cell population is not available. METHODS: We continuously exposed the human prostate epithelial stem/progenitor cell line WPE-stem to an environmentally relevant level of arsenic (5 microM) in vitro and determined the acquired cancer phenotype. RESULTS: WPE-stem cells rapidly acquired a malignant CSC-like phenotype by 18 weeks of exposure, becoming highly invasive, losing contact inhibition, and hyper-secreting matrix metalloproteinase-9. When hetero-transplanted, these cells (designated As-CSC) formed highly pleomorphic, aggressive tumors with immature epithelial- and mesenchymal-like cells, suggesting a highly pluripotent cell of origin. Consistent with tumor-derived CSCs, As-CSCs formed abundant free-floating spheres enriched in CSC-like cells, as confirmed by molecular analysis and the fact that only these floating cells formed xeno-graft tumors. An early loss of NSC self-renewal gene expression (p63, ABCG2, BMI-1, SHH, OCT-4, NOTCH-1) during arsenite exposure was sub-sequently reversed as the tumor suppressor gene PTEN was progressively suppressed and the CSC-like phenotype acquired. CONCLUSIONS: Arsenite transforms prostate epithelial stem/progenitor cells into CSC-like cells, indicating that it can produce CSCs from a model NSC population.",
Arsenic,1797812,"Essential and toxic element concentrations in blood and urine and their associations with diet: Results from a Norwegian population study including high-consumers of seafood and game Abstract: The first aim of the study was to evaluate calculated dietary intake and concentrations measured in blood or urine of essential and toxic elements in relation to nutritional and toxicological reference values. The second aim was to identify patterns of the element concentrations in blood and urine and to identify possible dietary determinants of the concentrations of these elements. Adults with a known high consumption of environmental contaminants (n=111), and a random sample of controls (n=76) answered a validated food frequency questionnaire (FFQ). Complete data on biological measures were available for 179 individuals. Blood and urine samples were analyzed for selenium, iodine, arsenic, mercury, cadmium and lead. Principal component analysis was used to identify underlying patterns of correlated blood and urine concentrations. The calculated intakes of selenium, iodine, inorganic arsenic and mercury were within guideline levels. For cadmium 24% of the high consumer group and 8% of the control group had intakes above the tolerable weekly intake. Concentrations of lead in blood exceeded the bench-mark dose lower confidence limits for some participants. However, overall, the examined exposures did not give rise to nutritional or toxicological concerns. Game consumption was associated with lead in blood (Bln 0.021; 95%CI:0.010, 0.031) and wine consumption. Seafood consumption was associated with urinary cadmium in non-smokers (Bln 0.009; 95%CI:0.003, 0.015). A novel finding was a distinct pattern of positively associated biological markers, comprising iodine, selenium, arsenic and mercury (eigenvalue 3.8), reflecting seafood intake (B 0.007; 95%CI:0.004, 0.010). The study clearly demonstrates the significance of seafood as a source of both essential nutrients and toxic elements simultaneously and shows that exposure to various essential and toxic elements can be intertwined.",
Arsenic,1797783,"Immunomodulatory role of Emblica officinalis in arsenic induced oxidative damage and apoptosis in thymocytes of mice Abstract: <strong>BACKGROUND: </strong>Arsenic is widely distributed in the environment and has been found to be associated with the various health related problems including skin lesions, cancer, cardiovascular and immunological disorders. The fruit extract of Emblica officinalis (amla) has been shown to have anti-oxidative and immunomodulatory properties. In view of increasing health risk of arsenic, the present study has been carried out to investigate the protective effect of amla against arsenic induced oxidative stress and apoptosis in thymocytes of mice.<br /><br /><strong>METHODS: </strong>Mice were exposed to arsenic (sodium arsenite 3 mg/kg body weight p.o.) or amla (500 mg/kg body weight p.o.) or simultaneously with arsenic and amla for 28 days. The antioxidant enzyme assays were carried out using spectrophotometer and generation of ROS, apoptotic parameters, change in cell cycle were carried out using flow cytometer following the standard protocols.<br /><br /><strong>RESULTS: </strong>Arsenic exposure to mice caused a significant increase in the lipid peroxidation, ROS production and decreased cell viability, levels of reduced glutathione, the activity of superoxide dismutase, catalase, cytochrome c oxidase and mitochondrial membrane potential in the thymus as compared to controls. Increased activity of caspase-3 linked with apoptosis assessed by the cell cycle analysis and annexin V/PI binding was also observed in mice exposed to arsenic as compared to controls. Co-treatment with arsenic and amla decreased the levels of lipid peroxidation, ROS production, activity of caspase-3, apoptosis and increased cell viability, levels of antioxidant enzymes, cytochrome c oxidase and mitochondrial membrane potential as compared to mice treated with arsenic alone.<br /><br /><strong>CONCLUSIONS: </strong>The results of the present study exhibits that arsenic induced oxidative stress and apoptosis significantly protected by co-treatment with amla that could be due to its strong antioxidant potential.",
Arsenic,2064216,Preparation and reactivity of molybdenum-dinitrogen complexes bearing an arsenic-containing ANA-type pincer ligand Abstract: Novel mono- and dimolybdenum-dinitrogen complexes bearing an arsenic-containing ANA-type pincer ligand are prepared and characterized by X-ray analyses. These complexes afford a stoichiometric amount of ammonia by treatment with sulfuric acid at room temperature.,
Arsenic,2345800,"Amendment application in a multi-contaminated mine soil: effects on soil enzymatic activities and ecotoxicological characteristics Abstract: Several amendments were tested on soils obtained from an arsenopyrite mine, further planted with Arrhenatherum elatius and Festuca curvifolia, in order to assess their ability to improve soil's ecotoxicological characteristics. The properties used to assess the effects were: soil enzymatic activities (dehydrogenase, ?-glucosidase, acid phosphatase, urease, protease and cellulase), terrestrial bioassays (Eisenia fetida mortality and avoidance behaviour), and aquatic bioassays using a soil leachate (Daphnia magna immobilisation and Vibrio fischeri bioluminescence inhibition). The treatment with FeSO4 1 % w/w was able to reduce extractable As in soil, but increased the extractable Cu, Mn and Zn concentrations, as a consequence of the decrease in soil pH, in relation to the unamended soil, from 5.0 to 3.4, respectively. As a consequence, this treatment had a detrimental effect in some of the soil enzymatic activities (e.g. dehydrogenase, acid phosphatase, urease and cellulase), did not allow plant growth, induced E. fetida mortality in the highest concentration tested (100 % w/w), and its soil leachate was very toxic towards D. magna and V. fischeri. The combined application of FeSO4 1 % w/w with other treatments (e.g. CaCO3 1 % w/w and paper mill 1 % w/w) allowed a decrease in extractable As and metals, and a soil pH value closer to neutrality. As a consequence, dehydrogenase activity, plant growth and some of the bioassays identified those as better soil treatments to this type of multi-contaminated soil.",
Arsenic,2347607,"Tolerance to individual and joint effects of arsenic and Bacillus thuringiensis subsp. israelensis or Lysinibacillus sphaericus in Culex mosquitoes Abstract: Arsenic contamination of global water supplies has come to the forefront in policy decisions in recent decades. However, the effects of arsenic on lower trophic levels of insects inhabiting contaminated ecosystems are not well understood. One approach to document both acute and sublethal effects of toxicants like arsenic is to assay them in combination with microbial pathogens to evaluate shifts in survival curves of the test organisms. Larvae of Culex quinquefasciatus and Culex tarsalis were reared in water containing 0 or 1?000 ?g/L of arsenate or arsenite. Fourth instars were then exposed to a range of doses of Bacillus thuringiensis subsp. israelensis (Bti) or Lysinibacillus sphaericus (Ls), with shifts in lethal concentrations determined. Arsenic accumulation in 4th instars was also quantified, and a relative growth index (RGI) calculated for the treatments and compared to controls. Larvae of both species accumulated between 4?447 ± 169 ng As/g and 6?983 ± 367 ng As/g, though RGI values indicated accumulation did not affect growth and development. In all cases, the LC50 's and LC90 's of Cx. quinquefasciatus exposed jointly with arsenic and Bti/Ls were higher than Cx. tarsalis. Cx. tarsalis reared in arsenite showed a significant reduction in their Bti LC90 values compared to the control, indicating a sublethal effect of Bti. When exposed jointly with Ls, arsenite was more toxic than arsenate in Cx. tarsalis. Overall, these results indicate tolerance of these Culex species to arsenic exposures, and why this may occur is discussed.",
Arsenic,1034873,"Incorporation of C14-thymidine and C14-uridine nucleosides into nucleic acid molecules in the liver of mice exposed to trivalent arsenic in drinking water Abstract: The effect of trivalent arsenic on the C14-thymidine and C14-uridine incorporation into the liver nucleic acid molecules was studied in groups of mice exposed to 3.3 mmol . l-1 sodium arsenite in drinking water for 2, 4, 8, 16 and 32 days. In each exposure group, 18 h before the animals were killed by decapitation, six to ten mice were injected with 0.1 ml of C14-thymidine or C14-uridine of an activity of 0.37 MBq. The radioactivity of liver DNA and liver RNA fractions isolated and separated by extraction from the mouse liver homogenate was measured on a Betazcint BZ 5,000 scintillation counter and expressed as cpm . mg-1 of isolated nucleic acids. Initially, the rates at which the labeled thymidine and uridine nucleosides incorporated into the nucleic acid molecules showed a marked drop below the control value, then started to rise again, continuing to gradually increase as the time of arsenic exposure was increasing; they attained the control value on day 8, and at the last interval of observation (i.e. at 32 days of exposure to arsenic) they reached, respectively, 143% and 127% of the control value. The initial drop in the rate of nucleoside incorporation is believed to reflect the general metabolic inhibition caused by arsenic; the subsequent enhancement of the process of incorporation is ascribed to the induction of enzymes that are involved in the development of a tolerance for arsenic.",
Arsenic,1353953,"Protein kinase C activation inhibits stress-induced synthesis of heat shock protein 27 in osteoblast-like cells: Function of arachidonic acid Abstract: Exposure of osteoblast-like MC3T3-E1 cells to sodium arsenite (arsenite) increased the level of heat shock protein 27 (hsp27). The effect of arsenite was dose-dependent in the range of 50 to 200 microM. Arsenite also stimulated arachidonic acid release dose-dependently in the range between 50 and 200 microM in these cells. Both indomethacin, an inhibitor of cyclooxygenase, and nordihydroguaiaretic acid, a lipoxygenase inhibitor, significantly enhanced the arsenite-induced accumulation of hsp27. Melittin, an activator of phospholipase A2, significantly enhanced the arsenite-induced accumulation of hsp27. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, inhibited the arsenite-induced accumulation of hsp27. In contrast, 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), a PKC-nonactivating phorbol ester, had little effect. TPA suppressed the arsenite-induced arachidonic acid release, but 4 alpha-PDD had little effect. Arsenite no longer affected cAMP accumulation, inositol phosphates formation nor the formation of choline and phosphocholine in these cells. These results suggest that the response to stress of hsp27 is coupled with the metabolic activity of the arachidonic acid cascade, and the activation of PKC inhibits the induction of hsp27 through the suppression of arachidonic acid release in osteoblast-like cells.",
Arsenic,1240309,"Combined neutralization-adsorption system for the disposal of hydrothermally altered excavated rock producing acidic leachate with hazardous elements Abstract: Hydrothermally altered rock excavated in a tunnel project produces acidic leachate containing hazardous elements that include arsenic (As), lead (Pb), copper (Cu) and zinc (Zn). To mitigate this problem, this paper evaluated a combined neutralization-adsorption system that used readily available and cheap reagents like calcium carbonate (CaCO3) and partly-weathered volcanic ash. Batch neutralization experiments showed that CaCO3 was effective in raising the pH of the leachate around neutral while the batch adsorption experiments illustrated that the volcanic ash sample collected near the tunnel project area was highly capable of adsorbing arsenate (As[V]), Pb, Cu and Zn. Under column conditions, the amount of hazardous elements released from the rock increased by several folds and their breakthrough curves had flushing-out trends. The mechanisms of As and heavy metals release probably include the dissolution of soluble phases and pyrite oxidation. Addition of CaCO3 in the column experiments based on estimates from the batch results underestimated the amount of neutralizer needed to adjust the effluent pH to around 8, resulting only in slight increase of the pH. Nevertheless, the presence of CaCO3 drastically reduced the amount of hazardous elements released from the altered rock especially during the initial stages of the column experiments. Combining neutralization and adsorption effectively reduced the amount of As and heavy metals in the effluent throughout the duration of the column experiments, which is attributed to the slight neutralizing effect of volcanic ash that raised the pH around circumneutral as well as its rich Al and Fe oxyhydroxide/oxide contents. The combined system immobilized the hazardous elements through a combination of co-precipitation and adsorption reactions and showed potential as an alternative method for the disposal of altered rocks producing acidic leachate.",
Arsenic,1349394,Family aggregation of chronic arsenic poisoning associated with indoor burning of high arsenic coal Abstract: ,
Arsenic,2149164,"Arsenic accumulation by edible aquatic macrophytes Abstract: Edible aquatic macrophytes grown in arsenic (As)-contaminated soil and sediment were investigated to determine the extent of As accumulation and potential risk to humans when consumed. Nasturtium officinale (watercress) and Diplazium esculentum (warabi) are two aquatic macrophytes grown and consumed in Hawaii. Neither has been assessed for potential to accumulate As when grown in As-contaminated soil. Some former sugarcane plantation soils in eastern Hawaii have been shown to have concentrations of total As over 500mgkg(-1). It was hypothesized that both species will accumulate more As in contaminated soils than in non-contaminated soils. N. officinale and D. esculentum were collected in areas with and without As-contaminated soil and sediment. High soil As concentrations averaged 356mgkg(-1), while low soil As concentrations were 0.75mgkg(-1). Average N. officinale and D. esculentum total As concentrations were 0.572mgkg(-1) and 0.075mgkg(-1), respectively, corresponding to hazard indices of 0.12 and 0.03 for adults. Unlike previous studies where watercress was grown in As-contaminated water, N. officinale did not show properties of a hyperaccumulator, yet plant concentrations in high As areas were more than double those in low As areas. There was a slight correlation between high total As in sediment and soil and total As concentrations in watercress leaves and stems, resulting in a plant uptake factor of 0.010, an order of magnitude higher than previous studies. D. esculentum did not show signs of accumulating As in the edible fiddleheads. Hawaii is unique in having volcanic ash soils with extremely high sorption characteristics of As and P that limit release into groundwater. This study presents a case where soils and sediments were significantly enriched in total As concentration, but the water As concentration was below detection limits.",
Arsenic,1022273,"A potential mechanism for the impairment of nitric oxide formation caused by prolonged oral exposure to arsenate in rabbits Abstract: We have recently found evidence for impairment of nitric oxide (NO) formation and induction of oxidative stress in residents of an endemic area of chronic arsenic poisoning in Inner Mongolia, China. To investigate the underlying mechanisms responsible for these phenomena, a subchronic animal experiment was conducted using male New Zealand White rabbits. After 18 weeks of continuous exposure of rabbits to 5 mg/l of arsenate in drinking water, a significant decrease in systemic NO production occurred, as shown by significantly reduced plasma NO metabolites levels (76% of control) and a tendency towards decreased serum cGMP levels (81.4% of control). On the other hand, increased oxidative stress, as shown by significantly increased urinary hydrogen peroxide (H(2)O(2)) (120% of control), was observed in arsenate-exposed rabbits. In additional experiments measuring aortic tension, the addition of either the calcium ionophore A23187 or acethylcholine (ACh) induced a transient vasoconstriction of aortic rings prepared from arsenate-exposed rabbits, but not in those prepared from control animals. This calcium-dependent contractility action observed in aorta rings from arsenate-exposed rabbits was markedly attenuated by the superoxide (O2(.-)) scavenging enzyme Cu, Zn-SOD, as well as diphenyleneiodonium (DPI) or N(G)-nitro-L-arginine methyl ester (L-NAME), which are inhibitors for nitric oxide synthase (NOS). However, the cyclooxygenase inhibitor indomethacin or the xanthine oxidase blocker allopurinol had no effect on this vasoconstriction. These results suggest that arsenate-mediated reduction of systemic NO may be associated with the enzymatic uncoupling reaction of NOS with a subsequent enhancement of reactive oxygen species such as O2(.-), an endothelium-derived vasoconstricting factor. Furthermore, hepatic levels of (6R)-5,6,7,8-tetrahydro-L-biopterin (BH(4)), a cofactor for NOS, were markedly reduced in arsenate-exposed rabbits to 62% of control, while no significant change occurred in cardiac L-arginine levels. These results suggest that prolonged exposure of rabbits to oral arsenate may impair the bioavailability of BH(4) in endothelial cells and, as a consequence, disrupt the balance between NO and O2(.-) produced from endothelial NOS, such that enhanced free radicals are produced at the expense of NO.",
Arsenic,2347600,"Plant chitinase responses to different metal-type stresses reveal specificity Abstract: <strong>KEY MESSAGE: </strong>Chitinases in Glycine max roots specifically respond to different metal types and reveal a polymorphism that coincides with sensitivity to metal toxicity. Plants evolved various defense mechanisms to cope with metal toxicity. Chitinases (EC 3.2.1.14), belonging to so-called pathogenesis-related proteins, act as possible second line defense compounds in plants exposed to metals. In this work their activity was studied and compared in two selected soybean (Glycine max L.) cultivars, the metal-tolerant cv. Chernyatka and the sensitive cv. Kyivska 98. Roots were exposed to different metal(loid)s such as cadmium, arsenic and aluminum that are expected to cause toxicity in different ways. For comparison, a non-metal, NaCl, was applied as well. The results showed that the sensitivity of roots to different stressors coincides with the responsiveness of chitinases in total protein extracts. Moreover, detailed analyses of acidic and neutral proteins identified one polymorphic chitinase isoform that distinguishes between the two cultivars studied. This isoform was stress responsive and thus could reflect the evolutionary adaptation of soybean to environmental cues. Activities of the individual chitinases were dependent on metal type as well as the cultivar pointing to their more complex role in plant defense during this type of stress.",
Arsenic,1347253,"Differences in hearing aid performance: As related to clinical hearing aid evaluations Abstract: Considerable differences of opinion still exist concerning the validity, reliability, and value of performance comparisons of hearing aids in clinical hearing aid evaluations or selections. A number of research audiologists contend that no real differences in aids can be demonstrated, while many clinically oriented audiologists show results from their experience of differences of considerable magnitude. An analysis of 298 hearing aid evaluations in our clinical laboratory using peak performance, current aids preselected as suitable for each patient, showed that large differences between the poorest and best performing aids occurred frequently. In our series, 47% of the patients showed differences of 20% or more in speech discrimination between aids and 86% showed differences of 10% or more.",
Arsenic,627460,"Organic anion transporting polypeptide-C mediates arsenic uptake in HEK293 cells Abstract: Arsenic is an established human carcinogen. The role of aquaglyroporins (AQPs) in arsenic disposition was recently identified. In order to examine whether organic anion transporting polypeptide-C (OATP-C) also plays a role in arsenic transport, OATP-C cDNA was transfected into cells of a human embryonic kidney cell line (HEK-293). Transfection increased uptake of the model OATP-C substrate, estradiol-17beta-D-glucuronide, by 10-fold. In addition, we measured uptake and cytotoxicity of arsenate, arsenite, monomethylarsonate(MMA(V)), and dimethylarsinate (DMA(V)). Transfection of OATP-C increased uptake and cytotoxicity of arsenate and arsenite, but not of MMA(V) or DMA(V). Rifampin and taurocholic acid (a substrate of OATP-C) reversed the increased toxicity of arsenate and arsenite seen in OATP-C-transfected cells. The increase in uptake of inorganic arsenic was not as great as that of estradiol-17beta-D-glucuronide. Our results suggest that OATP-C can transport inorganic arsenic in a (GSH)-dependent manner. However, this may not be the major pathway for arsenic transport.",
Arsenic,1250967,"Absence of Detectable Arsenate in DNA from Arsenate-Grown GFAJ-1 Cells Abstract: A strain of Halomonas bacteria, GFAJ-1, has been claimed to be able to use arsenate as a nutrient when phosphate is limiting, and to specifically incorporate arsenic into its DNA in place of phosphorus. However, we have found that arsenate does not contribute to growth of GFAJ-1 when phosphate is limiting and that DNA purified from cells grown with limiting phosphate and abundant arsenate does not exhibit the spontaneous hydrolysis expected of arsenate ester bonds. Furthermore, mass spectrometry showed that this DNA contains only trace amounts of free arsenate and no detectable covalently bound arsenate.",
Arsenic,2337064,"Antioxidant effects of propolis on carp Cyprinus carpio exposed to arsenic: biochemical and histopathologic findings Abstract: Propolis, a resinous material produced by worker bees from the leaf buds and exudates of plants, is reported to possess various therapeutic properties. The aim of this study was to investigate the effects of propolis on biochemical parameters and histopathologic findings in carp Cyprinus carpio L. exposed to arsenic. A sublethal concentration of arsenic (0.01 mg l-1) and/or 10 mg l-1 propolis were administered to fish for 1 wk. Catalase (CAT) activities and malondialdehyde (MDA) levels were determined in liver, gill and muscle tissues in control, arsenic only, propolis only and arsenic+propolis treatment groups. Results showed that CAT activity decreased in the arsenic group compared to the control and propolis groups. CAT activity in the arsenic+propolis group was significantly higher compared to the arsenic group. MDA levels in fish exposed to 0.01 mg l-1 arsenic significantly increased compared to the control group. However, MDA levels in the arsenic+propolis group were significantly lower compared to the arsenic group. Histopathological changes in the liver, gill and muscle tissues of carp were examined by light microscopy: various changes were observed in all tissues of fish in the arsenic group. Propolis showed important antioxidant effects against arsenic toxicity in all fish tissues.",
Arsenic,628625,"Decreased serum concentrations of nitric oxide metabolites among Chinese in an endemic area of chronic arsenic poisoning in inner Mongolia Abstract: Prolonged exposure to arsenic results in peripheral and cardiovascular manifestations, as does impaired production of endothelial nitric oxide (NO). In vitro studies have indicated that endothelial cells undergo damage by arsenic. However, no information has been available on the relationship between NO synthesis and chronic arsenic poisoning in humans. The present study was designed to reveal this question. The subjects were 33 habitants who continued to drink well water containing high concentrations of inorganic arsenic (mean value = 0.41 microg/ml) for about 18 years in Inner Mongolia, China, and 10 other people who lived in this area but exposed to minimal concentrations of arsenic (mean value = 0.02 microg/ml) were employed as controls. Mean blood concentration of total arsenic was six times higher in exposed subjects than controls; 42.1 vs. 7.3 ng/ml, p <.001. Mean serum concentration of nitrite/nitrate, stable metabolites of endogenous NO, was lower in arsenic-exposed subjects than in controls: 24.7 vs. 51.6 microM, p<.001. In total samples, an inverse correlation with serum nitrite/nitrate levels was strong for blood inorganic arsenic (r = -0.52, p <.001) and less strong for its metabolites, monomethyl arsenic (r = -0.45, p<.005) and dimethyl arsenic (r = -0.37, p<.05). Furthermore, serum nitrite/nitrate concentration was significantly correlated with nonprotein sulfhydryl level in whole blood (r = 0.58, p<.001). In an in vitro study, we demonstrated that inorganic arsenite or arsenate suppresses the activity of endothelial NO synthase in human umbilical vein endothelial cells. These results suggest that long-term exposure to arsenic by drinking well water possibly reduces NO production in endothelial cells, resulting in a decrease in reduced nitrite/nitrate concentrations. Peripheral vascular disorders caused by arsenic may be attributable in part to impairment of NO production in vivo.",
Arsenic,744876,"Toxicogenomical study on human bladder epithelium exposed to arsenic Abstract: In this study, human urothelium (UROtsa) cells were exposed to arsenite [As(III)- 30 ?M], monomethylarsenous acid [MMA(III)1-5 ?M], or buthionine sulfoximine [BSO-25 ?M] followed by [As(III)-1? M] for up to 18 hr and the changes in gene expression determined by using a human oligonucleotide chip (18, 861 genes). The hybridizations were performed at least three times using independent total RNA preparations to ensure reproducibility. Differentially expressed genes were identified based on 2-fold cut off and gene significantly different from the control cells (t-test analysis, p<0.05). Only up-regulated genes have been assessed. Both As(III) and MMA(III) treatments produce an oxidative stress response. Interestingly, MMA(III) exposure for 6 hr did not induce any metallothionein genes but induced numerous unique genes [such as dual specificity phosphatase (DUSP1, DUSP2); CDC like kinase (CLK1); DNA damage inducible transcript (DD1T3)] and even caused greater increases in stress genes [e.g. heat shock protein (HSPA6, HSPA1A); DnaJ(HSP40)]. Reduction in cellular GSH content via BSO treatment followed by As(III) exposure for 6 hr exacerbrate the gene expressionmodifying effects of arsenite on UROtsa cells. The induction of heat shock protein (HSPA1A, HSPA6); metallothionein (MT1G); and solute carrier family (SLC30A) genes revealed synergistic effects of cytotoxicity for both AsIII and BSO. These results indicate that oxidative stress must be a common pathway in cellular response to exposure to different arsenicals. Furthermore, As(III) and MMA(III) induce genes involved in similar but different pathways. The absence of metallothionein gene induction by MMA (III) exposure may demonstrate different mechanism of recognition by the UROtsa cells or mechanism of toxicity.",
Arsenic,1003602,"Oxidation of arsenite by two ?-proteobacteria isolated from soil Abstract: Two heterotrophic As(III)-oxidizing bacteria, SPB-24 and SPB-31 were isolated from garden soil. Based on 16S rRNA gene sequence analysis, strain SPB-24 was closely related to genus Bordetella, and strain SPB-31 was most closely related to genus Achromobacter. Both strains exhibited high As(III) (15 mM for SPB-24 and 40 mM for SPB-31) and As(V) (>300 mM for both strains) resistance. Both strains oxidized 5 mM As(III) in minimal medium with oxidation rate of 554 and 558 ?M h(-1) for SPB-24 and SPB-31, respectively. Washed cells of both strains oxidized As(III) over broad pH and temperature range with optimum pH 6 and temperature 42°C for both strains. The As(III) oxidation kinetic by washed cells showed K (m) and V (max) values of 41.7 ?M and 1,166 ?M h(-1) for SPB-24, 52 ?M and 1,186 ?M h(-1) for SPB-31. In the presence of minimal amount of carbon source, the strains showed high As(III) oxidation rate and high specific arsenite oxidase activity. The ability of strains to resist high concentration of arsenic and oxidize As(III) with highest rates reported so far makes them potential candidates for bioremediation of arsenic-contaminated environment.",
Arsenic,628375,"The temporal stability of arsenic concentrations in well water in western Nevada Abstract: Millions of people worldwide are exposed to drinking water containing arsenic, and epidemiologic studies have identified associations between the ingestion of arsenic-contaminated water and increased risks of cancer. In many of these studies, the assessment of arsenic exposure is based on a limited number of drinking water measurements, and the assessment of long-term or past exposure relies on the assumption that arsenic concentrations in sources of drinking water remain stable over time. In this investigation, the temporal stability of arsenic concentration was assessed in 759 wells in western Nevada state in the USA. Arsenic concentrations in these wells ranged from nondetectable to 6200 ?g/L (median, 10 ?g/L; standard deviation, 335 ?g/L). Spearman correlation coefficients between arsenic concentrations measured in the same wells over a period of 1–5, 6–10, and 11–20 years apart were, respectively, 0.84 [95% confidence interval (CI), 0.81–0.86), 0.85 (95% CI, 0.81–0.88), and 0.94 (95% CI, 0.88–0.96). These findings suggest that, in this study area, arsenic concentrations in most wells remain stable over time and a limited number of measurements per well can be used to predict arsenic exposures over a period of many years.",
Arsenic,2278245,"Leaching characteristics of arsenic-containing solid waste Abstract: Leaching characteristics of arsenic-containing lime-iron salt solid waste produced from treatment of wastewater generated from sulfuric acid production were investigated under various pHs, leaching times and calcination temperatures. The leached concentrations of As, Cd, Zn, Cu and Pb from arsenic-containing solid waste immersed in simulated acid rain were also determined. The results showed that the leached concentrations of arsenic and other heavy metals decreased with increasing pH and increased slightly with increasing leaching time; the leached concentrations of arsenic exceeded 11 mg/L in the simulated acid rain and increased with increasing calcination temperature in the range of 300-1100 degrees C, while the leached concentrations of other hea",
Arsenic,1255517,"Arsenic exposure and DNA methylation among elderly men Abstract: BACKGROUND:: Arsenic exposure has been linked to epigenetic modifications such as DNA methylation in in-vitro and animal studies. This association has also been explored in highly exposed human populations, but studies among populations environmentally exposed to low arsenic levels are lacking. METHODS:: We evaluated the association between exposure to arsenic, measured in toenails, and blood DNA methylation in Alu and Long Interspersed Nucleotide Element-1 (LINE-1) repetitive elements in elderly men environmentally exposed to low levels of arsenic. We also explored potential effect modification by plasma folate, cobalamin (vitamin B12), and pyridoxine (vitamin B6). The study population was 581 participants from the Normative Aging Study in Boston, of whom 434, 140, and 7 had 1, 2, and 3 visits, respectively, between 1999-2002 and 2006-2007. We used mixed-effects models and included interaction terms to assess potential effect modification by nutritional factors. RESULTS:: There was a trend of increasing Alu and decreasing LINE-1 DNA methylation as arsenic exposure increased. In subjects with plasma folate below the median (<14.1 ng/mL), arsenic was positively associated with Alu DNA methylation (? = 0.08 [95% confidence interval = 0.03 to 0.13] for one interquartile range [0.06 ?/g] increase in arsenic), whereas a negative association was observed in subjects with plasma folate above the median (? = -0.08 [-0.17 to 0.01]). CONCLUSION:: We found an association between arsenic exposure and DNA methylation in Alu repetitive elements that varied by folate level. This suggests a potential role for nutritional factors in arsenic toxicity.",
Arsenic,1936170,"Assessment of the Heavy Metal Contents of Sardina pilchardus Sold in Izmir, Turkey Abstract: ",
Arsenic,472970,"Impact of trivalent arsenicals on selenoprotein synthesis Abstract: BACKGROUND: Exposure to arsenic has been associated with development of skin, lung, bladder, liver, and kidney cancer. Recent evidence suggests that an increase in oxidative stress in cells treated with arsenicals represents the molecular mechanism behind arsenic-induced carcinogenesis. Selenium, in the form of selenocysteine, is necessary for the activity of several enzymes with a role in defense against reactive oxygen species. A mutual sparing effect between arsenic and selenium has been shown in animal studies when both metalloids are present in high concentrations. OBJECTIVES: To determine whether changes in selenoprotein synthesis may be an underlying mechanism behind arsenic-induced carcinogenesis, we analyzed the new synthesis of selenoproteins within cells after exposure to inorganic or methylated arsenicals using a human keratinocyte cell model. RESULTS: Addition of arsenite to culture medium blocked new synthesis of selenoproteins when selenium was present in the form of selenite, and appeared to stimulate the use of serum-derived selenium. Monomethylarsonous acid (MMA(III)) treatment of cells, in contrast, did not block all new synthesis of selenoproteins but did result in an increase in cytosolic thioredoxin reductase (TrxR1) at both the mRNA and protein levels. MMA(III) also reduced the new synthesis of cellular glutatione peroxidase (cGpx) and other smaller selenoproteins. Dimethylarsinous acid (DMA(III)) stimulated selenoprotein synthesis by an as yet unknown mechanism. CONCLUSIONS: These results suggest that arsenite and MMA(III) are key metabolites that trigger higher levels of TrxR1, and both lead to a reduction in the expression of cGpx. Together these effects certainly could lead to carcinogenesis given the knowledge that many cancers have higher levels of TrxR, and reduced Gpx levels will reduce the cell's ability to defend against reactive oxygen species. Based on these results, the impact of the trivalent arsenicals arsenite and MMA(III) on selenoprotein synthesis may indeed represent a potential molecular mechanism for the higher rates of cancer observed in populations exposed to high levels of arsenic.",
Arsenic,1508519,"Efficacy of indigenous soil microbes in arsenic mitigation from contaminated alluvial soil of India Abstract: Selected arsenic-volatilizing indigenous soil bacteria were isolated and their ability to form volatile arsenicals from toxic inorganic arsenic was assessed. Approximately 37 % of AsIII (under aerobic conditions) and 30 % AsV (under anaerobic conditions) were volatilized by new bacterial isolates in 3 days. In contrast to genetically modified organism, indigenous soil bacteria was capable of removing 16 % of arsenic from contaminated soil during 60 days incubation period while applied with a low-cost organic nutrient supplement (farm yard manure).",
Arsenic,2345613,"Sealing rice field boundaries in Bangladesh: a pilot study demonstrates reductions in water use, arsenic loading to field soils, and methane emissions from irrigation water Abstract: Irrigation of rice fields in Bangladesh with arsenic-contaminated and methane-rich groundwater loads arsenic into field soils and releases methane into the atmosphere. We tested the water-savings potential of sealing field bunds (raised boundaries around field edges) as a way to mitigate these negative outcomes. We found that on average, bund sealing reduced seasonal water use by 52±17% and decreased arsenic loading to field soils by 15±4%; greater savings in both water use and arsenic loading were achieved in fields with larger perimeter-to-area ratios (i.e., smaller fields). Our study is the first to quantify emission of methane from irrigation water in Bangladesh, a currently unaccounted-for methane source. Irrigation water applied to unsealed fields at our site emits 18 to 31 g of methane per square-meter of field area per season, potentially doubling the atmospheric input of methane from rice cultivation. Bund sealing reduced the emission of methane from irrigation water by 4 to 19 g/m2. While the studied outcomes of bund sealing are positive and compelling, widespread implementation of the technique should consider other factors, such as effect on yields, financial costs, and impact on the hydrologic system. We provide an initial and preliminary assessment of these implementation factors.",
Arsenic,2347684,"Evaluation of the use of common sculpin (Myoxocephalus scorpius) organ histology as bioindicator for element exposure in the fjord of the mining area Maarmorilik, West Greenland Abstract: The former Black Angel lead-zinc mine in Maarmorilik, West Greenland, is a historic example of how mining activity may result in a significant impact on the surrounding fjord system in terms of elevated concentrations of especially lead (Pb) and zinc (Zn) in seawater, sediments and surrounding biota. In order to shed light on the present contamination and possible effects in the fjord we initiated a range of studies including a pilot study on gill and liver morphology of common sculpins (Myoxocephalus scorpius) around Maarmorilik. Sculpins were caught and sampled at five different stations known to represent a gradient of Pb concentrations. Fish livers from all specimens were analyzed for relevant elements in the area: Fe, Zn, As, Cu, Se, Cd, Pb, Ag, Hg, Co and Ni. Lead, As and Hg showed significant differences among the five stations. For 20% of the sculpins, Hg concentrations were in the range of lowest observed effect dose (LOED) of 0.1-0.5?g/gww for toxic threshold on reproduction and subclinical endpoints. Likewise LOEDs for tissue lesions, LOEDs for biochemistry, growth, survival and reproduction were exceeded for Cd (0.42-1.8?g/gww) and for As (11.6?g/gww) in 28% and 85% of the sculpins, respectively. Similar to this, the no observed effect dose (NOED) for biochemistry was exceeded for Pb (0.32?g/gww) and for growth, mortality and reproduction for Zn (60-68?g/gww) in 33% and 24% of the sculpins, respectively. For all sculpins, females were significantly larger than males and for five of the elements (Fe, Co, Ni, Cu, Se) females had higher concentrations. The chronic lesions observed in liver (mononuclear cell infiltrates, necrosis, vacuolar hepatocytes, portal fibrosis, bile duct hyperplasia, active melanomacrophage centers) and gills (fusion and edema of secondary lamellae, laminar telangiectasis, mononuclear cell infiltrates, blebs) were similar to those in the literature studies for both wild and laboratory exposed sculpins and other fish species carrying similar or higher Hg concentrations. Ignoring sex and size, specimens with hepatic cell infiltrates had the highest concentrations of most elements, a relation that was also found for gill telangiectasis and Hg (all p&lt;0.05). When controlling for sex and size, the prevalence of vacuolar hepatocytes and endoparasites was significantly highest at the three most contaminated stations and similar differences were found for liver necrosis. We suggest that beside exposure to mining-related elements, other environmental factors, such as parasites, might be co-factors in the development of the observed liver and gill lesions. Therefore, sculpin liver and gill pathology are likely to be suitable health indicators when biomonitoring gradients of mining and other element related activity effects; while a larger study is required to fully evaluate the relationships.",
Arsenic,1032282,"Exposure to neurotoxic metals among workers in Singapore: An overview Abstract: The extent of occupational exposure to inorganic lead, manganese, arsenic and inorganic mercury in Singapore was determined from the results of Statutory Medical Examinations and environmental monitoring carried out by the Department of Industrial Health in 1989. There were 786 workers exposed to lead. Of these, 7.8 per cent had blood levels greater than 40 micrograms/dl. There were 67 workers exposed to mercury, 11.9 per cent of whom had urinary mercury levels greater than 50 micrograms/l. There were 101 and 144 workers exposed to arsenic and manganese respectively. None of the biological samples exceeded the health-based limits. A review of local studies showed that some of the exposed workers had neurophysiological and neurobehavioural changes.",
Arsenic,2088367,"[Preliminary characterization of water quality in the high basin of river Del Valle (Catamarca)] Abstract: In the province of Catamarca, the basin of river Del Valle is the most important which concentrates populations, agricultural and industrial activity along its route. The objective of this work was measure the quality of water in the upper basin of the river Del Valle is in the initial trainers in this river. The results obtained from the sampling allowed to determine that the quality of the water of this river is generally aceptable for irrigation and consumption. One of the rivers (river Los Puestos) that flow into river Del Valle, have a content of something more arsenic than the rest of the basin, although it does not affect the quality of the river Del Valle, must be considered its existence by the use of this water for irrigation and consumption of the inhabitants of this area.",
Arsenic,2343526,"Arsenic uptake by Lemna minor in hydroponic system Abstract: Arsenic is hazardous and causes several ill effects on human beings. Phytoremediation is the use of aquatic plants for the removal of toxic pollutants from external media. In the present research work, the removal efficiency as well as the arsenic uptake capacity of duckweed Lemna minor has been studied. Arsenic concentration in water samples and plant biomass were determined by AAS. The relative growth factor of Lemna minor was determined. The duckweed had potential to remove as well as uptake arsenic from the aqueous medium. Maximum removal of more than 70% arsenic was achieved atinitial concentration of 0.5 mg/1 arsenic on 15th day of experimental period of 22 days. Removal percentage was found to decrease with the increase in initial concentration. From BCF value, Lemna minor was found to be a hyperaccumulator of arsenic at initial concentration of 0.5 mg/L, such that accumulation decreased with increase in initial arsenic concentration.",
Arsenic,1033990,"Potential toxicity due to dolomite and bonemeal Abstract: Large amounts of dolomite and bonemeal are being consumed, especially by nutrition-conscious persons. The mineral content of commercial samples has been analyzed by different laboratories, and significant amounts of lead, arsenic, mercury, and other potentially toxic metals, which also exist in conventional vitamin-mineral and calcium supplements, were detected. Physicians must consider the possibility of unrecognized self-poisoning from the consumption of such substances, especially in the context of unexplained neurologic, gastrointestinal, cutaneous, and hematologic disorders. The use of dolomite and bonemeal by pregnant women, children with suspected milk allergy, and elderly persons requires careful evaluation.",
Arsenic,2337273,"Geochemistry of mine tailings and behavior of arsenic at Kombat, northeastern Namibia Abstract: The mine tailings at Kombat, in semiarid northeastern Namibia, were investigated by the combination of solid-phase analyses, mineralogical methods, leaching tests, and speciation modeling. Dissolution of the most abundant primary sulfides, chalcopyrite and galena, released copper and lead which were adsorbed onto ferric oxyhydroxides or precipitated in the form of malachite, Cu2CO3(OH)2, and cerussite, PbCO3, respectively. Arsenic released from arsenopyrite was incorporated into ferric oxyhydroxides. Based on sequential extraction and (57)Fe Mössbauer spectroscopy, a large amount of ferric iron is present as low solubility hematite and goethite formed rapidly (&lt;10 years) under warm semiarid climatic conditions, and arsenic in these phases is relatively tightly bound. It seems that Cu and especially Pb in carbonate minerals represent a more serious environmental risk. Immobilization of As in hematite has implications for other mining sites in regions with similar climatic conditions because this process results in long-term immobilization of As.",
Arsenic,1936135,Screening of plant growth-promoting traits in arsenic-resistant bacteria isolated from the rhizosphere of soybean plants from Argentinean agricultural soil Abstract: ,
Arsenic,1786296,"Amino-functionalized MCM-41 and MCM-48 for the removal of chromate and arsenate Abstract: The aim of the present work was to investigate the efficiency of three amino-functionalized (hexadecylamine, dodecylamine, and dimethyldodecylamine) mesoporous silicas (MCM-41 and MCM-48) toward the adsorption of arsenate and chromate. Hexadecylamine-functionalized materials were characterized; BET surface areas, pore volumes, and sizes decreased with the functionalization, whereas XRD patterns show that the hexagonal structure of MCM-41 and the cubic structure of MCM-48 were not modified. The zeta potential decreases with pH and the highest arsenate and chromate removal was observed at the lowest pHs. Adsorption of chromium and arsenate was significantly enhanced after functionalization and amino-functionalized MCM-41 adsorb larger amounts of arsenate when compared to expanded MCM-48 materials. Chromate sorption capacities increased with the chain length and the larger capacities were obtained with hexadecylamine-functionalized mesoporous silicas. Mesoporous silicas modified by dimethyldodecylamine exhibited the higher arsenate sorption capacities.",
Arsenic,1033220,"A reformulation of the serially additive expected dose method for occupational cohort data Abstract: The serially additive expected dose method for the analysis of occupational cohort data can be biased whenever worker exposure is associated with length of follow-up. An illustration shows that this bias can act to either enhance or reduce the degree of association between disease and exposure. The serially additive expected dose method can be modified, then embedded in a classical Cox proportional hazards model context to eliminate the analytic bias. A chisquare test of no exposure association is derived.",
Arsenic,628803,"Arsenic trioxide-mediated growth inhibition in MC/CAR myeloma cells via cell cycle arrest in association with induction of cyclin-dependent kinase inhibitor, p21, and apoptosis Abstract: We investigated the in vitro effect of As2O3 on proliferation, cell cycle regulation, and apoptosis in human myeloma cell lines. As2O3 significantly inhibited the proliferation of all of eight myeloma cell lines examined in a dose-dependent manner with IC50 of approximately 1-2 microM. DNA flow cytometric analysis indicated that As2O3 (2 microM) induced a G1 and/or a G2-M phase arrest in these cell lines. To address the mechanism of the antiproliferative effect of As2O3, we examined the effect of As2O3 on cell cycle-related proteins in MC/CAR cells in which both G1 and G2-M phases were arrested. Western blot analysis demonstrated that treatment with As2O3 (2 microM) for 72 h did not change the steady-state levels of CDK2, CDK4, cyclin D1, cyclin E, and cyclin B1 but decreased the levels of CDK6, cdc2, and cyclin A. The mRNA and protein levels of CDKI, p21 were increased by treatment with As2O3, but those of p27 were not. In addition, As2O3 markedly enhanced the binding of p21 with CDK6, cdc2, cyclin E, and cyclin A compared with untreated control cells. Furthermore, the activity of CDK6-associated kinase was reduced in association with hypophosphorylation of Rb protein. The activity of cdc2-associated kinase was decreased, which was accompanied by the up-regulation of cdc2 phosphorylation (cdc2-Tyr15 phosphorylation) resulting from reduction of cdc25B and cdc25C phosphatases. As2O3 also induced apoptosis in MC/CAR cells as evidenced by flow cytometric detection of sub-G1 DNA content and annexin V binding assay. This apoptotic process was associated with down-regulation of Bcl-2, loss of mitochondrial transmembrane potential (delta psi(m)), and an increase of caspase-3 activity. These results suggest that As2O3 inhibits the proliferation of myeloma cells, especially MC/CAR cells, via cell cycle arrest in association with induction of p21 and apoptosis.",
Arsenic,2149109,"Assessment of Infantile Mineral Imbalances in Autism Spectrum Disorders (ASDs) Abstract: The interactions between genes and the environment are now regarded as the most probable explanation for autism. In this review, we summarize the results of a metallomics study in which scalp hair concentrations of 26 trace elements were examined for 1,967 autistic children (1,553 males and 414 females aged 0-15 years-old), and discuss recent advances in our understanding of epigenetic roles of infantile mineral imbalances in the pathogenesis of autism. In the 1,967 subjects, 584 (29.7%) and 347 (17.6%) were found deficient in zinc and magnesium, respectively, and the incidence rate of zinc deficiency was estimated at 43.5% in male and 52.5% in female infantile subjects aged 0-3 years-old. In contrast, 339 (17.2%), 168 (8.5%) and 94 (4.8%) individuals were found to suffer from high burdens of aluminum, cadmium and lead, respectively, and 2.8% or less from mercury and arsenic. High toxic metal burdens were more frequently observed in the infants aged 0-3 years-old, whose incidence rates were 20.6%, 12.1%, 7.5%, 3.2% and 2.3% for aluminum, cadmium, lead, arsenic and mercury, respectively. These findings suggest that infantile zinc- and magnesium-deficiency and/or toxic metal burdens may be critical and induce epigenetic alterations in the genes and genetic regulation mechanisms of neurodevelopment in the autistic children, and demonstrate that a time factor &quot;infantile window&quot; is also critical for neurodevelopment and probably for therapy. Thus, early metallomics analysis may lead to early screening/estimation and treatment/prevention for the autistic neurodevelopment disorders.",
Arsenic,1519095,"Isolated limb infusion in a series of over 100 infusions: A single-center experience Abstract: <strong>BACKGROUND: </strong>Isolated limb infusion (ILI) is a therapeutic option for patients with recurrent, unresectable extremity malignancies.<br /><br /><strong>METHODS: </strong>A prospectively collected single-institution database of patients undergoing ILI was analyzed for preoperative, intraoperative, and postoperative parameters and outcomes.<br /><br /><strong>RESULTS: </strong>From May 2007 to January 2012, a total of 76 patients successfully underwent initial ILI, and 28 after either previous hyperthermic isolated limb perfusion or ILI. Seventy-nine patients (74 %) had melanoma, 24 (22 %) sarcoma, 3 (3 %) Merkel cell, and 1 (1 %) squamous cell carcinoma. There were 55 (72 %) initial and 22 (79 %) repeat lower extremity (LE) ILIs, and 21 (78 %) initial and 6 (22 %) repeat upper extremity (UE) ILIs. Serologic toxicity, measured by serum creatine kinase (CK), peaked higher and later in LE ILIs, median 620 versus 124 IU/L, and postoperative day 4 versus 2, respectively (P &lt; 0.05). LE ILIs had a longer hospital length of stay (LOS), median 6 versus 5 days (P &lt; 0.0001). A median grade II Wieberdink regional toxicity was observed. Three-month follow-up was available in 94 (90 %). A response (overall response rate, ORR) was seen in 72 % of ILIs performed for melanoma and 58 % for sarcoma. No difference in response was observed between UE versus LE or between initial versus repeat ILIs. Repeat UE ILIs, however, appeared to have an improved ORR than repeat LE ILIs, 83 versus 64 %.<br /><br /><strong>CONCLUSIONS: </strong>ILI may be successfully performed for cutaneous and soft tissue malignancies. LE ILIs have higher CK levels and slightly longer LOS. Repeat ILIs are not associated with increased toxicity and similar ORR. UE ILIs may have better ORR.",
Arsenic,2345804,"Large-scale geographical variation in eggshell metal and calcium content in a passerine bird (Ficedula hypoleuca) Abstract: Birds have been used as bioindicators of pollution, such as toxic metals. Levels of pollutants in eggs are especially interesting, as developing birds are more sensitive to detrimental effects of pollutants than adults. Only very few studies have monitored intraspecific, large-scale variation in metal pollution across a species' breeding range. We studied large-scale geographic variation in metal levels in the eggs of a small passerine, the pied flycatcher (Ficedula hypoleuca), sampled from 15 populations across Europe. We measured 10 eggshell elements (As, Cd, Cr, Cu, Ni, Pb, Zn, Se, Sr, and Ca) and several shell characteristics (mass, thickness, porosity, and color). We found significant variation among populations in eggshell metal levels for all metals except copper. Eggshell lead, zinc, and chromium levels decreased from central Europe to the north, in line with the gradient in pollution levels over Europe, thus suggesting that eggshell can be used as an indicator of pollution levels. Eggshell lead levels were also correlated with soil lead levels and pH. Most of the metals were not correlated with eggshell characteristics, with the exception of shell mass, or with breeding success, which may suggest that birds can cope well with the current background exposure levels across Europe.",
Arsenic,627996,"Atherogenicity and carcinogenicity of high-arsenic artesian well water. Multiple risk factors and related malignant neoplasms of blackfoot disease Abstract: The objective of this study was to examine multiple risk factors and correlated malignant neoplasms of blackfoot disease (BFD), a unique peripheral vascular disease related to continuous exposure to high-arsenic artesian well water. A total of 241 BFD cases, including 169 with spontaneous or surgical amputations of affected extremities, and 759 age-sex-residence-matched healthy community controls were studied to explore the risk factors of BFD. Multiple logistic regression analysis showed that artesian well water consumption, arsenic poisoning, familial history of BFD, and undernourishment were significantly associated with the development of BFD. The life-table method used to analyze cancer mortality of 789 BFD patients followed for 15 years showed a significantly higher mortality from cardiovascular diseases, peripheral vascular diseases, and cancers of bladder, skin, lung, and liver among BFD patients as compared with the general population in Taiwan or residents in the BFD-endemic area. The results imply the atherogenicity and carcinogenicity of the artesian well water in the BFD-endemic area.",
Arsenic,1020659,"Thiol synthesis and arsenic hyperaccumulation in Pteris vittata (Chinese brake fern) Abstract: Pteris vittata (Chinese brake fern) has potential for phytoremediation of As-contaminated sites. In this study, the synthesis of total thiols and acid-soluble thiols in P. vittata was investigated under arsenic exposure. The strong and positive correlation between As concentration and acid-soluble thiols in plant leaflets suggests that acid-soluble thiols may play a role in As detoxification. A major As-induced thiol was purified and characterized. A molecular ion (M + 1) of 540 m/z suggests that the thiol was a phytochelatin (PC) with two base units (PC(2)). However, the ratios of acid-soluble thiols to As in leaflets exposed to As ranged from 0.012 to 0.026, suggesting that only a very small part of As is complexed by PC(2). PCs could play a minor detoxification role in this hyperaccumulator. A PC-independent mechanism appears to be mainly involved in As tolerance, while PC-dependent detoxification seems to be a supplement.",
Arsenic,1357222,"A Mysterious Yellow-White Paste: Evaluation of an Unanticipated Contaminant Abstract: The potential and unanticipated exposure to arsenic (7440382) contaminants detected in an uranium enrichment process was examined. Employees discovered an unusual deposit described as a yellow/white paste blocking instrument lines. The paste was identified as arsenic-pentoxide (1303282). NIOSH performed a health hazards evaluation at the site, which assessed the airborne levels of arsenic compounds. Personal and area air samples were collected at three locations in one process building and at one location in the converter maintenance facility. Time weighted average (TWA) exposures were calculated. Personal exposure to arsenic among workers removing an evacuation booster valve varied from 1 to 109 micrograms per cubic meter (microg/m3), with an average exposure level of 37microg/m3. A chemical operator who performed the decontamination process had the highest exposure level. The 8 hour TWAs calculated for all samples ranged from below detection to 22microg/m3 of arsenic. All employees working within the radiological contamination areas wore personal protective clothing. In addition, most workers wore supplied air respiratory protection. The personal samplers were worn outside of the garments. The author concludes that the monitoring of arsenic exposure at this workplace should focus on reducing and maintaining arsenic at the lowest possible concentration.",
Arsenic,2149081,"Seasonal variation of metals in seawater, sediment, and Manila clam Ruditapes philippinarum from China Abstract: Concentrations of trace metals (Cu, Pb, Zn, Cd, Cr, Hg, and As) were determined for the first time in seawater, sediment, and Manila clam from Deer Island, Liaoning Province, China. The seawater, sediment, and clam samples were collected seasonally at three clam farming sites around Deer Island during 2010-2011. The average concentrations of Cu, Pb, Zn, Cd, Cr, Hg, and As in the seawater samples were 4.16, 0.72, 5.88, 0.45, 2.51, 0.03, and 1.02 ?g/l, respectively. The seasonal variations of trace metals in seawater showed a significant difference in the concentrations of Cu, Pb, Zn, Hg, and As among seasons. The average concentrations of Cu, Pb, Zn, Cd, Cr, Hg, and As in the sediment samples were 6.43, 13.80, 53.08, 1.10, 36.40, 0.05, and 4.78 mg/kg dry weight, respectively. Trace metal concentrations in sediment seasonally varied significantly except for Cd and Hg. The average concentrations of Cu, Pb, Zn, Cd, Cr, Hg, and As in the clam samples were 11.28, 0.61, 92.50, 0.58, 3.98, 0.03, and 1.98 mg/kg dry weight, respectively. Concentrations of Cu, Zn, Cd, Cr, and As in Manila clam showed marked seasonal fluctuations with significant difference. Cu and Zn were the metals with the highest mean biosediment accumulation factor values in Manila clam. Besides, significant correlations for the concentrations of Cu and Zn relative to their concentrations in sediment were also found. Such differences in regression analyzes may be explained by differential bioaccumulation of essential and xenobiotic metals. Concentrations of trace metals in Manila clam did not exceed the maximum established regulatory concentrations for human consumption. Moreover, the calculations revealed that the estimated daily intake values for the examined clam samples were below the internationally accepted dietary guidelines and the calculated hazard quotient values were well less than 1, thus strongly indicating that health risk associated with the intake studied metals through the consumption of Manila clam from Deer Island was absent.",
Arsenic,627804,"DNA-strand breaks induced by dimethylarsinic acid, a metabolite of inorganic arsenics, are strongly enhanced by superoxide anion radicals Abstract: We previously reported that dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenics, induced DNA single-strand breaks (ssb) both in vivo and in cultured alveolar type II (L-132) cells in vitro, possibly via the production of dimethylarsenic peroxyl radicals. Here, the interaction of superoxide anion radicals (O2-) in the induction of ssb in L-132 cells was investigated using paraquat, an O2(-)-producing agent. A significant enhancement of ssb formation was observed in the DMAA-exposed cells when coexposed to paraquat. This enhancement occurred even when post-exposed to DMAA after washing, suggesting that the DMAA exposure caused some modification of DNA such as DNA-adducts, which was recognized by active oxygens to form ssb. An experiment with UV-irradiation, which was likely to induce ssb at the modified region, supported the possibility of DNA modification by DMAA exposure. An ESR study indicated that O2- produced by paraquat in DMAA-exposed cells was more consumed than in non-exposed cells, assumingly through the reaction with the dimethylarsenic-modified region of DNA. The species of active oxygens were estimated by using diethyldithiocarbamate, aminotriazole, diethylmaleate, hydrogen peroxide (H2O2), gamma-irradiation and ethanol. O2- but neither H2O2 nor hydroxyl radicals was very likely to contribute to the ssb-enhancing action of paraquat.",
Arsenic,1337283,"Effect of subchronic exposure to arsenic on levels of essential trace elements in mice brain and its gender difference Abstract: The interactions of toxic metals with essential metals may result in disturbances in the homeostasis of essential elements. However, there are few reports about toxic effect of arsenic (As) on the levels of essential trace elements in the central nervous system. To investigate whether subchronic exposure to As disturbs levels of main essential trace elements in the brain of mice and whether the gender difference in the response to As are altered, the concentrations of As, Iron (Fe), copper (Cu), selenium (Se), zinc (Zn) and Chromium (Cr) in the cerebrum and cerebellum of mice exposed to As subchronically were examined by inductively coupled plasma-mass spectrometry (ICP-MS). The gender difference in the changed levels of these essential trace elements was also statistically analyzed. The concentration of As was significantly higher in the cerebrum or cerebellum of mice exposed to As than that in control group (P &lt; 0.05). It indicates that As can accumulate in brain of mice after subchronic exposure. The concentrations of Fe, Se and Cr in the cerebrum or cerebellum were significantly lower in mice exposed to As than those in control group (P &lt; 0.05). On the contrary, the concentration of Cu in the cerebrum or cerebellum was significantly higher in mice exposed to As (P &lt; 0.05). Our results indicate that subchronic exposure to As may decrease the levels of Fe, Se and Cr or increase the level of Cu in the brain of mice. Moreover, the significant gender difference was found relative to the effect of As on concentration of Se in cerebrum and concentrations of Cu and Se in cerebellum of mice. Therefore, more experiments are required to further understand mechanisms whereby As interacts with essential elements in brain and induces the gender difference.",
Arsenic,1337326,"Modeling the Effect of Charge Density in the Active Layers of Reverse Osmosis and Nanofiltration Membranes on the Rejection of Arsenic(III) and Potassium Iodide Abstract: We used an extended solution-diffusion model that incorporates Donnan electrostatic exclusion of ions and unhindered advection due to imperfections, and measurements of charge density in the polyamide active layers of reverse osmosis (RO) and nanofiltration (NF) membranes, to predict the rejection of a strong electrolyte (i.e., potassium iodide) and a weak acid (i.e., arsenious acid) as a function of the pH of the feed aqueous solution. Predictions of solute rejection were in agreement with experimental data indicating that (i) the extended solution-diffusion model taking into account Donnan exclusion and unhindered advection due to imperfections satisfactorily describes the effect of pH on solute rejection by RO/NF membranes and (ii) measurement of charge density in active layers provides a valuable characterization of RO/NF membranes. Our results and analysis also indicate that independent ions, and not ion pairs, dominate the permeation of salts.",
Arsenic,710997,"No association between arsenic exposure from drinking water and diabetes mellitus: A cross-sectional study in Bangladesh Abstract: The long-term effects of arsenic exposure from drinking water at levels &lt; 300 microg/L and the risk of diabetes mellitus remains a controversial topic.<br /><br /> We conducted a population-based cross-sectional study using baseline data from 11,319 participants in the Health Effects of Arsenic Longitudinal Study in Araihazar, Bangladesh, to evaluate the associations of well water arsenic and total urinary arsenic concentration and the prevalence of diabetes mellitus and glucosuria. We also assessed the concentrations of well water arsenic, total urinary arsenic, and urinary arsenic metabolites in relation to blood glycosylated hemoglobin (HbA1c) levels in subsets of the study population.<br /><br /> More than 90% of the cohort members were exposed to drinking water with arsenic concentration &lt; 300 microg/L. We found no association between arsenic exposure and the prevalence of diabetes. The adjusted odds ratios for diabetes were 1.00 (referent), 1.35 [95% confidence interval (CI), 0.90-2.02], 1.24 (0.82-1.87), 0.96 (0.62-1.49), and 1.11 (0.73-1.69) in relation to quintiles of time-weighted water arsenic concentrations of 0.1-8, 8-41, 41-91, 92-176, and &gt; or = 177 microg/L, respectively, and 1.00 (referent), 1.29 (0.87-1.91), 1.05 (0.69-1.59), 0.94 (0.61-1.44), and 0.93 (0.59-1.45) in relation to quintiles of urinary arsenic concentrations of 1-36, 37-66, 67-114, 115-204, and &gt; or = 205 microg/L, respectively. We observed no association between arsenic exposure and prevalence of glucosuria and no evidence of an association between well water arsenic, total urinary arsenic, or the composition of urinary arsenic metabolites and HbA1c level.<br /><br /> Our findings do not support an association of arsenic exposure from drinking water and a significantly increased risk of diabetes mellitus in the range of levels observed. Further prospective studies would be valuable in confirming the findings.",
Arsenic,734977,"Carcinogenic effects of ""whole-life"" exposure to inorganic arsenic in CD1 mice Abstract: In a previously developed mouse model, arsenic exposure in utero induces tumors at multiple sites in the offspring as adults, often duplicating human targets. However, human environmental inorganic arsenic exposure occurs during the entire life span, not just part of gestation. Thus, ""whole-life"" inorganic arsenic carcinogenesis in mice was studied. CD1 mice were exposed to 0, 6, 12, or 24 ppm arsenic in the drinking water 2 weeks prior to breeding, during pregnancy, lactation, and after weaning through adulthood. Tumors were assessed in offspring until 2 years of age. Arsenic induced dose-related increases in lung adenocarcinoma (both sexes), hepatocellular carcinoma (both sexes), gallbladder tumors (males), and uterine carcinomas. Arsenic induced dose-related increases in ovarian tumors (including carcinomas) starting with the lowest dose. Adrenal tumors increased at all doses (both sexes). Arsenic-induced lung and liver cancers were highly enriched for cancer stem cells, consistent with prior work with skin cancers stimulated by prenatal arsenic. Reproductive tract tumors overexpressed cyclooxygenase-2 and estrogen receptor-?. Arsenic target sites were remarkably similar to prior transplacental studies, although tumors from whole-life exposure were generally more aggressive and frequent. This may indicate that arsenic-induced events in utero dictate target site in some tissues, whereas other exposure periods of arsenic enhance incidence or progression, though other factors could be at play, like cumulative dose. Whole-life arsenic exposure induced tumors at dramatically lower external doses than in utero arsenic only while more realistically duplicating human exposure.",
Arsenic,1030825,"Significance of urinary arsenic speciation in assessment of seafood ingestion as the main source of organic and inorganic arsenic in a population resident near a coastal area Abstract: In order to characterize the different sources of exposure to arsenic (As), urinary excretion of total As, the sum of inorganic As+MMA+DMA determined by the hydride generation-atomic absorption spectrophotometry technique, and the species As3, As5, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine were determined in 49 workers at a steel foundry, with presumed occupational exposure to As, and 50 subjects from the general population, all males. No evidence of occupational exposure to As resulted from environmental monitoring performed in the foundry, although the analysis of minerals used as raw materials showed the presence of As, particularly in fossils and fine ores. The urinary concentrations of As3, MMA, DMA, the sum of inorganic As+MMA+DMA and total As were not different in the two groups, while arsenobetaine appeared significantly higher in the controls than in the workers. The different species of urinary As were all significantly correlated. Urinary excretion of As3 was associated with the consumption of mineral water and with residence in an industrial zone, while MMA, DMA, arsenobetaine, the sum of inorganic As+MMA+DMA and total As urinary excretion were associated with the consumption of crustaceans and/or shellfish 3 days or less before urine collection. Multiple regression analysis confirmed these results. In conclusion, in populations with a high consumption of seafood, living in areas characterized by coastal/marine As pollution, only speciation of As can identify a prevalent role of environmental sources, like the consumption of seafood contaminated by As, in determining urinary As excretion, and exclude an occupational origin of the exposure.",
Arsenic,1936095,"Dual role of resveratrol in modulation of genotoxicity induced by sodium arsenite via oxidative stress and apoptosis Abstract: The potential benefits of resveratrol as an anticancer (proapoptosis) and antioxidant (pro-survival) compound have been studied extensively. However, the role of resveratrol in modulation of the toxicity induced by sodium arsenite (NaAsO2) is still unclear. In the present study, we examined the effects of resveratrol on NaAsO2-induced cytotoxicity, DNA and chromosomal damage, cell cycle progression, apoptosis and oxidative stress in human lung adenocarcinoma epithelial (A549) cell line at concentrations from 1 to 20?M after 24h exposure. Our results revealed that at 1 and 5?M, resveratrol was found to exert benefit effects, promoting cell viability and proliferation over 24h NaAsO2 exposure, whereas, resveratrol was showed to inhibit cell survival under the same condition at 20?M. Corresponding to the opposing effect of resveratrol at low vs. high concentrations, DNA and chromosomal damage, cell apoptotic rate and level of oxidative stress were also alleviated by lower concentrations (1, 5?M) of resveratrol, but exacerbated by higher concentration (20?M) resveratrol. Our study implicates that resveratrol is the most beneficial to cells at 1 and 5?M and caution should be taken in applying resveratrol as an anticancer therapeutic agent or nutraceutical supplement due to its concentration dependent effect.",
Arsenic,1579352,"Biomarkers of renal toxicity caused by exposure to arsenic in drinking water Abstract: This study is intended to explore effective and sensitive biomarkers for kidney damage after low level arsenic (As) exposure and to provide scientific evidence on cut-off values of arsenic concentrations in drinking water. The levels of ?1-MG detected in urine samples were found to have statistically significant differences between high As group (As&gt;0.05mg/L) and a combination of low and medium As exposure groups (As&lt;0.05mg/L, p=0.018), as well as between the patient and high As groups (As in two group were both higher than 0.05mg/L, p&lt;0.001). After the logistic regression analysis the AUC values of ?1-MG between two comparisons were 0.613 and 0.701, and p value was less than 0.05. The present data demonstrate the potential value of ?1-MG excretion as a biomarker of renal toxicity, which could contribute to the enforcement of the maximum limit of 0.05mg/L arsenic in drinking water for non-central water supply in rural areas.",
Arsenic,627306,"Protective effects of fruit extracts of Hippophae rhamnoides L. against arsenic toxicity in Swiss albino mice Abstract: Seabuckthorn (Hippophae rhamnoides L.) berry has a long history of applications as a food and medicinal ingredient in eastern countries. The present study was carried out to investigate the effect of different fruit extracts of H. rhamnoides on altered biochemical parameters indicative of haematological alterations, tissue oxidative stress, and arsenic concentration in arsenic-exposed mice (2.5 mg/kg body weight, intraperitoneally). Two aqueous extracts (at room temperature and under reflux condition) and an ethanolic extract of H. rhamnoides at a dose of 500 mg/kg body weight were co-administered daily during arsenic exposure in mice for 3 weeks. Exposure to arsenic led to a significant inhibition of blood delta-aminolevulinic acid dehydratase (ALAD) activity, suggesting disturbed haem synthesis pathway. Arsenic also caused significant depletion of reduced hepatic glutathione (GSH) level, glutathione S-transferase (GST) and glutathione peroxidase and catalase activities, while it increased the level of thiobarbituric acid reactive substance (TBARS), suggesting liver oxidative stress. Most of the altered biochemical variables responded favorably to the co-supplementation of H. rhamnoides, particularly the aqueous fruit extract, extracted at room temperature (HF-WRT). However, arsenic concentration in blood and tissues remained unchanged, suggesting the lack of chelating property of fruit extract of H. rhamnoides. The present study, thus, led us to conclude that the fruit extract of H. rhamnoides has a significant protective role against arsenic-induced oxidative injury. However, it lacks the ability to remove arsenic from the binding sites, suggesting that the herbal extract could be co-administered with a chelating agent of known efficacy during treatment of arsenic to achieve the optimum effect of chelation treatment.",
Arsenic,1337298,"Reversible Inhibition of Co(2) Fixation By Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase Through the Synergic Effect of Arsenite and a Monothiol Abstract: The activity of the photosynthetic carbon-fixing enzyme, ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), is partially inhibited by arsenite in the millimolar concentration range. However, micromolar arsenite can fully inhibit Rubisco in the presence of a potentiating monothiol such as cysteine, cysteamine, 2-mercaptoethanol or N-acetylcysteine, but not glutathione. Arsenite reacts specifically with the vicinal Cys172-Cys192 from the large subunit of Rubisco and with the monothiol to establish a ternary complex which is suggested to be a trithioarsenical. The stability of the complex is strongly dependent on the nature of the monothiol. Enzyme activity is fully recovered through the disassembly of the complex after eliminating arsenite and/or the thiol from the medium. The synergic combination of arsenite and a monothiol acts also in vivo stopping carbon dioxide fixation in illuminated cultures of Chlamydomonas reinhardtii. Again, this effect may be reverted by washing the cells. However, in vivo inhibition does not result from the blocking of Rubisco since mutant strains carrying Rubiscos with Cys172 and/or Cys192 substitutions (which are insensitive to arsenite in vitro) are also arrested. This suggests the existence of a specific sensor controlling carbon fixation that is even more sensitive than Rubisco to the arsenite-thiol synergism.",
Arsenic,2337272,"Predicting primary PM2.5 and PM0.1 trace composition for epidemiological studies in California Abstract: The University of California-Davis_Primary (UCD_P) chemical transport model was developed and applied to compute the primary airborne particulate matter (PM) trace chemical concentrations from ?900 sources in California through a simulation of atmospheric emissions, transport, dry deposition and wet deposition for a 7-year period (2000-2006) with results saved at daily time resolution. A comprehensive comparison between monthly average model results and available measurements yielded Pearson correlation coefficients (R) ?0.8 at ?5 sites (out of a total of eight) for elemental carbon (EC) and nine trace elements: potassium, chromium, zinc, iron, titanium, arsenic, calcium, manganese, and strontium in the PM2.5 size fraction. Longer averaging time increased the overall R for PM2.5 EC from 0.89 (1 day) to 0.94 (1 month), and increased the number of species with strong correlations at individual sites. Predicted PM0.1 mass and PM0.1 EC exhibited excellent agreement with measurements (R = 0.92 and 0.94, respectively). The additional temporal and spatial information in the UCD_P model predictions produced population exposure estimates for PM2.5 and PM0.1that differed from traditional exposure estimates based on information at monitoring locations in California Metropolitan Statistical Areas, with a maximum divergence of 58% at Bakersfield. The UCD_P model has the potential to improve exposure estimates in epidemiology studies of PM trace chemical components and health.",
Arsenic,1016870,"Hair darkening in porphyria cutanea tarda Abstract: Repigmentation of grey hair is rare, but has been described in several clinical settings. It has most often been reported as a postinflammatory effect, but several drugs, chronic arsenic exposure and coeliac disease have also been cited in addition to darkening as a spontaneous phenomenon. We report two patients with sustained repigmentation of the hair in association with porphyria cutanea tarda. The mechanism for this repigmentation remains elusive, but presumably involves recruitment of outer root sheath melanocytes, which are then activated to form functional hair bulb melanocytes.",
Arsenic,1797772,"Indium diffusion and native oxide removal during the ALD of TiO2 films on InAs(100) surfaces Abstract: A thermal ALD process with tetrakis dimethyl amino titanium and H2O as reagents has been used to deposit TiO2 films on native oxide and etched InAs(100) surfaces at 200°C. TiO2 was deposited on etched InAs(100) surface without the formation of undesirable interfacial layers. X-ray photoelectron spectroscopy data on a series of films of increasing thickness deposited on surfaces covered with native oxide has shown that the surface arsenic oxides are removed within the first 2-3 nm of film deposition. The indium oxides however after an initial reduction seem to persist and increase in intensity with film thickness. For a 6.4 nm TiO2 film, x-ray photoelectron spectroscopy depth profile data demonstrate accumulation of indium oxides at the TiO2 film surface. When the topmost layer of the indium/TiO2 film is removed then a sharp interface between the TiO2 film and the InAs substrate is detected. This observation demonstrates that the surface oxides diffuse through fairly thick TiO2 films and may subsequently be removed by reaction with the precursor and amine by products of the ALD reaction. These finding underscore the importance of diffusion in understanding the so called &quot;interface clean-up&quot; reaction and its potential impact on the fabrication of high quality InAs and other III-V based MOS devices.",
Arsenic,627007,"Synergistic induction of apoptosis by sulindac and arsenic trioxide in human lung cancer A549 cells via reactive oxygen species-dependent down-regulation of survivin Abstract: Survivin, a member of the inhibitor of apoptosis protein (IAP) family, may be a good target for cancer therapy because it is expressed in a variety of human tumors but not in differentiated adult tissues. In the present study, we show that a combination of sulindac and arsenic trioxide (ATO) induces more extensive apoptosis than either drug alone in A549 human non-small cell lung carcinoma (NSCLC) cells. Treatment with sulindac/ATO reduced the expression of survivin and promoted major apoptotic signaling events, namely, collapse of the mitochondrial membrane potential, release of cytochrome c, and activation of caspases. Combined sulindac/ATO treatment did not significantly affect the levels of other members of the IAP family (XIAP, cIAP1 and cIAP2), indicating that the effects were specific to survivin. In addition, sulindac/ATO treatment induced the production of reactive oxygen species and the antioxidant N-acetyl-l-cysteine blocked the down-regulation of survivin and induction of apoptotic signaling by the combination of sulindac and ATO. Combined sulindac/ATO treatment also activated p53 expression, and inhibition of p53 expression by small interfering RNA (siRNA) prevented sulindac/ATO-induced down-regulation of survivin, suggesting that survivin expression is negatively regulated by p53. Overexpression of survivin reduced sulindac/ATO-induced apoptosis in A549 cells and reduction of survivin levels by siRNA sensitized the cells to sulindac/ATO-induced cell death. These results demonstrate that, in A549 human NSCLC cells, sulindac/ATO-induced apoptosis is mediated by the reactive oxygen species-dependent down-regulation of survivin.",
Arsenic,1704060,EFFECTS OF SEWAGE SLUDGE APPLICATION ON ARSENIC SPECIES IN POLLUTED SOILS Abstract: ,
Arsenic,1337527,"Hydration of arsenic oxyacid species Abstract: The bond distances in hydrated arsenic oxyacid species in aqueous solution have been studied by EXAFS spectroscopy and large angle X-ray scattering, LAXS. These results have been compared to structures in the solid state, as found in an extensive survey of available crystal structures. Protonated oxygen atoms can be distinguished with a longer As-O distance for both arsenic(v) and arsenic(iii) species in the crystalline state. However, the average As-O distance for the H(n)AsO(4)((3-n)-) species (0 ? n ? 3) remains the same. These average values are slightly shorter, ca. 0.02 Å, than in aqueous solution due to the hydration as determined by EXAFS and LAXS. The K absorption edges for arsenic(v) and arsenic(iii) species are separated by 4.0 eV, and the shape of the absorption edges differs as well. Small but significant differences in the absorption edge features are seen between the neutral acids and the charged oxyacid species. The most important arsenic species from an environmental point of view is arsenous acid, As(OH)(3). In addition to arsenous acid, we have used orthotelluric acid, Te(OH)(6), for comparison with arsenous acid and for detailed studies of the hydration of covalently bound hydroxo groups. Arsenous acid cannot be studied with the same accuracy as orthotelluric acid, due to a relatively low solubility of As(2)O(3)(s) in neutral to acidic aqueous solution. The results from the DDIR studies support the assignment of As(OH)(3) as a weak structure maker analogous to Te(OH)(6), both being neutral weak oxyacids.",
Arsenic,1337772,"Determination of trace elements in bovine semen samples by inductively coupled plasma mass spectrometry and data mining techniques for identification of bovine class Abstract: The reproductive performance of cattle may be influenced by several factors, but mineral imbalances are crucial in terms of direct effects on reproduction. Several studies have shown that elements such as calcium, copper, iron, magnesium, selenium, and zinc are essential for reproduction and can prevent oxidative stress. However, toxic elements such as lead, nickel, and arsenic can have adverse effects on reproduction. In this paper, we applied a simple and fast method of multi-element analysis to bovine semen samples from Zebu and European classes used in reproduction programs and artificial insemination. Samples were analyzed by inductively coupled plasma spectrometry (ICP-MS) using aqueous medium calibration and the samples were diluted in a proportion of 1:50 in a solution containing 0.01% (vol/vol) Triton X-100 and 0.5% (vol/vol) nitric acid. Rhodium, iridium, and yttrium were used as the internal standards for ICP-MS analysis. To develop a reliable method of tracing the class of bovine semen, we used data mining techniques that make it possible to classify unknown samples after checking the differentiation of known-class samples. Based on the determination of 15 elements in 41 samples of bovine semen, 3 machine-learning tools for classification were applied to determine cattle class. Our results demonstrate the potential of support vector machine (SVM), multilayer perceptron (MLP), and random forest (RF) chemometric tools to identify cattle class. Moreover, the selection tools made it possible to reduce the number of chemical elements needed from 15 to just 8.",
Arsenic,2343569,"MOISTURE AND INORGANIC SUBSTANCE CONTENT IN PINE TIMBER PRODUCTS FOR USE IN PELLETS AND BRIQUETTES Abstract: The forest industry in the municipal seat of Nuevo San Juan Parangaricutiro and the Indigenous Community of Nuevo San Juan Parangaricutiro, located in Michoacan state, Mexico, generates 1,232 m(3).year(-1) of underutilized pine sawdust and shavings. The sawdust and shavings of Pinus leiophylla Sch. Et Cham., P. montezumae Lamb. and P. pseudostrobus Lindl were subjected to physicochemical analyzes to determine if they meet the requirements for pellet and briquette production. The moisture, ash, and inorganic element contents in the byproducts were determined using international standards. Moisture content in ash was 51.5 +/- 1.9 %, and 53.7 +/- 0.1 % in shavings; these values exceeded the maximum allowable. Ash content in sawdust and shavings was 0.26 +/- 0.03 % and 0.34 +/- 0.03 %, respectively. For the three species evaluated, the average percentage of calcium, potassium, magnesium, phosphorus, sulfur, silicon, iron, aluminum and sodium in sawdust was 47.1 +/- 2.8, 26.0 +/- 2.5, 13.5 +/- 0.4, 5.0 +/- 0.4, 3.2 +/- 0.4, 2.3 +/- 0.8, 1.0 +/- 0.1, 1.3 +/- 0.4 and 1.4 +/- 0.3, respectively, while the average percentage was 43.2 +/- 7.0, 16.5 +/- 3.0, 10.1 +/- 4.8, 4.0 +/- 0.6, 1.8 +/- 0.2, 3.6 +/- 0.3, 1.0 +/- 0.6, 1.1 +/- 0.1 and 1.0 +/- 0.6 in shavings, respectively. Arsenic was only found in the shavings (17.1 +/- 17.1). Based on the results, sawdust is the most suitable byproduct for pellet and briquette production.",
Arsenic,62141,"Chronic arsenic poisoning in the north of Mexico Abstract: 1 We compared the prevalence of signs and symptoms of chronic arsenic poisoning in two rural populations. 2 The arsenic concentration in the drinking water of the exposed population was 0.41 mg/l, and 0.007 mg/l in the control population. 3 The arsenic was present mainly (70%) in its pentavalent form. 4 The objective was to quantitate health effects and risks derived from chronic ingestion of arsenic in contaminated water. 5 In the exposed population, 21.6% of the sample, showed at least one of the cutaneous signs of chronic arsenic poisoning against 2.2% in the control town. 6 Non-specific symptoms were more prevalent in the exposed population and they occurred more frequently in those individuals with skin signs. 7 The relative risk of suffering a particular manifestation of poisoning, ranged from 1.9 to 36 times higher in the exposed population. 8 We estimated the risks above mentioned, which were derived from exposure to minute quantities of arsenic in a known proportion of its oxidation states during a life time period.",
Arsenic,1019128,"Human urine certified reference material for arsenic speciation Abstract: <strong>BACKGROUND: </strong>Chemical speciation analysis is essential for the biological monitoring of inorganic arsenic exposure using urine as indicator medium. There is increasing demand for a certified reference material (CRM) of urine matrix for arsenic speciation.<br /><br /><strong>METHODS: </strong>Urine (10 L) was collected from non-occupationally exposed Japanese males. We prepared 954 bottles of urine, each containing approximately 10 mL, after filtering and blending the urine stock. The urine in each bottle was freeze-dried. Between-bottle homogeneity was confirmed by measuring the concentrations of selected minor and trace elements in the material and subsequent statistical analysis. Certification was based on a collaborative analysis involving 15 laboratories.<br /><br /><strong>RESULTS: </strong>Certified values were determined for arsenobetaine (0.069+/-0.012 mg As/L), dimethylarsinic acid (0.036+/-0.009 mg As/L), and total arsenic (0.134+/-0.011 mg/L) as well as for total selenium (0.059+/-0.005 mg/L) and zinc (0.62+/-0.05 mg/L), based on the analytical values from the collaborating laboratories. Reference values are given for copper (0.010 mg/L) and lead (0.0011 mg/L), based on definitive analysis at the National Institute for Environmental Studies (NIES).<br /><br /><strong>CONCLUSIONS: </strong>The present CRM, NIES CRM No. 18 Human Urine, is the first human urine CRM for arsenic speciation and will be of value for analytical quality assurance of the biological monitoring of arsenic exposure.",
Arsenic,628045,"Accumulation of arsenic in drinking water distribution systems Abstract: The tendency for iron solid surfaces to adsorb arsenic is well-known and has become the basis for several drinking water treatment approaches that remove arsenic. It is reasonable to assume that iron-based solids, such as corrosion deposits present in drinking water distribution systems, have similar adsorptive properties and could therefore concentrate arsenic and potentially re-release it into the distribution system. The arsenic composition of solids collected from drinking water distribution systems (pipe sections and hydrant flush solids), where the waters had measurable amounts of arsenic in their treated water, were determined. The elemental composition and mineralogy of 67 solid samples collected from 15 drinking water utilities located in Ohio (7), Michigan (7), and Indiana (1) were also determined. The arsenic content of these solids ranged from 10 to 13 650 microg of As/g of solid (as high as 1.37 wt %), and the major element of most solids was iron. Significant amounts of arsenic were even found in solids from systems that were exposed to relatively low concentrations of arsenic (<10 microg/L) in the water.",
Arsenic,1349687,"Pine pollen inhibits cell apoptosis-related protein expression in the cerebral cortex of mice with arsenic poisoning Abstract: Previous studies have demonstrated that pine pollen can inhibit cerebral cortical cell apoptosis in mice with arsenic poisoning. The present study sought to detect the influence of pine pollen on apoptosis-related proteins. Immunohistochemistry, western blotting and enzyme-linked immunosorbent assays were used to measure the levels of apoptosis-related proteins in the cerebral cortex of mice with arsenic poisoning. Results indicated that pine pollen suppressed cell apoptosis in the cerebral cortex of arsenic-poisoned mice by reducing Bax, Bcl-2 protein expression and increasing p53 protein expression.",
Arsenic,2149303,"DNA fragmentation, apoptosis and cell cycle arrest induced by sodium arsenite in cultured murine Sertoli cells: Prevention by curcumin Abstract: Arsenic is a significant environmental concern worldwide, primarily due to geo physiochemical contamination of drinking water, and a major public health hazard in both developing and developed countries. The present study was aimed to investigate ameliorative effects of curcumin (Cur) against sodium arsenite (SA)-induced toxicity in cultured murine Sertoli cells. The cells were treated with SA (5 ?M) and Cur (5 ?g/ml and 10 ?g/ml) alone or in combination for 12 hr. The SA treatment decreased cell viability, produced oxidative stress, and induced apoptosis as reflected by reactive oxygen species (ROS) generation, loss of mitochondrial transmembrane potential, DNA fragmentation, and apoptotic cells. Moreover, the SA-induced cell cycle arrest in the cells is characterized by a rise in the number of cells in the sub G1 phase of the cell cycle. The Cur was found to be effective in reversing all these arsenic (As)-induced cellular events. Data suggest that Cur modulates As-mediated oxidative stress, apoptosis, DNA fragmentation, and cell cycle arrest through suppression of excessive ROS generation. Evidence indicates that Cur may emerge as a useful protective agent against As-induced Sertoli cells toxicity by inhibiting As-induced damage in testes.",
Arsenic,2149119,"Coordinated response of sulfate transport, cysteine biosynthesis, and glutathione-mediated antioxidant defense in lentil (Lens culinaris Medik.) genotypes exposed to arsenic Abstract: Response of sulfate transporters, thiol metabolism, and antioxidant defense system was studied in roots of two lentil (Lens culinaris Medik.) genotypes grown in arsenic (10, 25, and 40 ?M As(V))-supplemented nutrient solution, and significant changes compared to control (0 ?M As(V)) were observed mainly at 25 and 40 ?M. In L 414, high glutathione (GSH) redox (0.8-0.9) was maintained with elevated thiol synthesis, powered by transcriptional up-regulation of LcSultr1;1 and LcSultr1;2 sulfate transporters and significant induction of LcSAT1;1 and LcSAT1;2 (serine acetyltransferase), OAS-TL (O-acetylserine(thiol)-lyase), ?-ECS (?-glutamylcysteine synthetase), and PCS (phytochelatin synthase) genes predominantly within 12-24 h of As exposure at 25 ?M and within 6-12 h at 40 ?M. This thiolic potency in L 414 roots was effectively complemented by up-regulation of gene expressions and consequent enhanced activities of superoxide dismutase, ascorbate peroxidase (APX), dehydroascorbate reductase, glutathione reductase (GR), and glutathione-S-transferase (GST) isoforms at 25 and 40 ?MAs, efficiently scavenging excess reactive oxygen species to prevent onset of As-induced oxidative stress and consequent inhibition of root growth in L 414. In contrast, down-regulation of vital sulfate-uptake transporters as well as entire thiol-metabolizing system and considerably low APX, GST, and GR expressions in DPL 59 not only resulted in reduced GSH redox but also led to over-accumulation of H2O2. This triggered membrane lipid peroxidations as the marks of As-induced oxidative damage. Results indicated coordinated response of thiol-metabolism and antioxidant defense in conferring As-tolerance in lentil, and GSH is the key point in this cascade.",
Arsenic,494799,"Baden-Wuerttemberg Environmental Health Survey (BW-EHS) from 1996 to 2003: Toxic metals in blood and urine of children Abstract: The environmental health surveillance system in the Federal State of Baden-Wuerttemberg (South Germany), among othe rs, was implemented to monitor pollutant exposures and their temporal and regional trends in children at the age of about 10 years. The investigations were performed in two larger cities, one small city and one rural area. Between 1996 and 2003, in total 5470 children were investigated in consideration of environmental health parameters in four cross-sectional studies. The data presented here cover the results of the determination of the internal load with toxic metals. The median values observed in the investigation in 2002/03 were: 4.6 mu g/l urine for arsenic, less than 0.2 mu g/l urine for mercury, 20.7 mu g/l blood for lead, and 0.25 mu g/l blood for cadmium. From 1996 to 2003, mercury concentrations showed a substantial decrease (-0.027 mu g/l/year) and lead levels also decreased (-0.25 mu g/l/year), whereas arsenic and cadmium levels did not change significantly over time. There was no consistent difference in the mean internal load of the metals between the four investigation areas. Important factors influencing the measured concentrations were consumption of fish in the last 48 h, which had an impact on arsenic (factor 2), and amalgam fillings, which accounted for an increase in mercury (factor 4.6). In the 2002/03 study period, levels above the limit of health concern for children (German HBM values) were found in about 0.5% of the lead measurements (maximum value 180 mu g/l blood) and in about 0.2% of the mercury measurements (maximum value 8.2 mu g/l urine). In conclusion, this environmental health survey generates objective data on secular trends and regional differences and provides insight into probable sources of toxic metal exposure in children. (C) 2007 Elsevier GmbH. All rights reserved.",
Arsenic,1327443,"Gallium arsenide augments antigen processing by peritoneal macrophages for CD4+ helper T cell stimulation Abstract: Gallium arsenide (GaAs) suppresses numerous immunologic functions of leukocytes at distal locations from the exposure site. The effect of direct GaAs exposure on peritoneal cells was examined by i.p. administration of the chemical. No alteration in the frequency of various cell lineages, including macrophages, B cells, CD4+ and CD8+ T cells, and granulocytes, occurred within the peritoneal population from GaAs-exposed mice. The ability of macrophages to function as antigen-presenting cells (APC) by processing a panel of soluble protein antigens was investigated by the stimulation of antigen-specific helper T cell hybridomas to secrete interleukin-2. On a per cell basis, GaAs-exposed macrophages were more efficient than vehicle control cells in activating the T cells with all native antigens examined. GaAs exposure increased the expression of major histocompatibility complex class II molecules, which are recognized by these T cells, on the surface of macrophages. However, the level of T cell activation with peptide fragments of the antigens, which do not require processing, was not enhanced with GaAs-exposed cells as APC. In contrast, the capability of latex bead-exposed macrophages to function as APC was comparable to that of vehicle control cells, suggesting that GaAs modulatory effects were not merely due to phagocytosis of particles. These findings suggest that direct GaAs exposure augments antigen processing, but not presentation, by macrophages perhaps by activating the cells, which may contribute to the immunotoxicity and inflammatory reaction caused by respiratory exposure to GaAs.",
Arsenic,69317,"Differential cytotoxic effects of arsenic on human and animal cells Abstract: Human fibroblasts (HFW) were 10-fold more susceptible than Chinese hamster ovary (CHO-K1) cells to sodium arsenite. Comparison of cellular antioxidant enzyme activities showed that CHO-K1 cells contained 3- and 8-fold more glutathione-peroxidase and catalase activities, respectively, than HFW cells. Since vitamin E, methylamine, and benzyl alcohol could prevent, in part, the arsenite-induced killing of HFW cells, we suggest that arsenite can induce oxidative damage in HFW cells. We have also established arsenic-resistant cells, SA7 and CL3R, from CHO cells and from a human lung adenocarcinoma cell line (CL3), respectively. The arsenic resistance of SA7 cells was attributed mainly to elevation of glutathione S-transferase pi levels, and that of CL3R cells was possibly due to an increase in heme oxygenase activity. Since induction of heme oxygenase is a general response to oxidative stress, we suspect that the differential toxicity of arsenic to human and animal cells could be due to arsenic's more efficient induction of oxidative damage in human cells.",
Arsenic,1033921,"Angiosarcoma of the liver: An epidemiologic survey Abstract: Diagnosed from 1970 through 1975, the annual incidence rate for angiosarcoma of the liver among residents of New York State (excluding New York City) was 0.25 per million. A case-control study indicated that direct exposure to arsenic, vinyl chloride (VC), and thorium dioxide was a significantly important factor in the etiology of this disorder (P less than 0.02). Direct exposure to these chemicals could not be demonstrated for 19 (73%) of the 26 study patients. The fact that 5 of these patients lived nearer to VC fabrication or polymerization plants than did their matched controls lent some support to the hypothesis that indirect modes of exposure, not specifically related to occupation, might be important in the etiology of this disorder.",
Arsenic,1337313,"Genome sequence of Galbibacter marinum type strain ck-I2-15 Abstract: Galbibacter marinum strain ck-I2-15(T) was isolated from an arsenite-resistant consortium enriched from the deep sea sediment of a hydrothermal vent field on the Southwest Indian Ocean Ridge. Here, we present the draft genome of strain ck-I2-15(T), which contains 3,572,447 bp with a G+C content of 37.04% and contains 3,099 protein-coding genes and 38 tRNA genes.",
Arsenic,1579316,"Impact of operative duration on postoperative pulmonary complications in laparoscopic versus open colectomy Abstract: BACKGROUND: Prolonged operative duration is associated with increased postoperative morbidity and mortality. Although laparoscopic colectomy (LC) is associated with longer operative duration compared with open colectomy (OC), research shows paradoxically decreased morbidity following LC versus OC. The direct impact of operative duration on postoperative pulmonary complications (PPC) following LC versus OC has not been analyzed. METHODS: We queried the ACS/NSQIP 2009-2010 Public Use File for patients who underwent elective LC and OC. The associations between operative duration and a PPC (pneumonia, intubation &gt;48 h, and unplanned intubation) were evaluated. Multivariable regression models were created to determine the independent effect of operative time on the development of PPC controlling for LC versus OC. RESULTS: A total of 25,419 colectomies (13,741 laparoscopic and 11,678 open) were reviewed; 765 (3 %) patients experienced at least one PPC. Regression modeling demonstrated that for both LC and OC each 60-min increase in operative time up to 480 min was associated with 13 % increased odds of PPC [odds ratio (OR) 1.13; 95 % confidence interval (CI) 1.07-1.19]. Beyond 480 min, each additional 60-min interval was associated with 33 % increased risk of PPC (OR 1.33; 95 % CI 1.12-1.58). Overall, PPCs occurred half as often following LC [270 (2 %) laparoscopic vs. 497 (4.3 %) open; OR 0.45; 95 % CI 0.39-0.53]. CONCLUSIONS: Operative duration is independently associated with increased risk of PPC in patients undergoing LC and OC. However, a laparoscopic approach carries half the absolute risk of PPC and, when safe, should be preferentially utilized despite a potential for prolonged operative duration.",
Arsenic,1337514,"Sodium arsenite exposure inhibits AKT and Stat3 activation, suppresses self-renewal and induces apoptotic death of embryonic stem cells Abstract: Sodium arsenite exposure at concentration >5 ?M may induce embryotoxic and teratogenic effects in animal models. Long-term health effects of sodium arsenite from contaminated drinking water may result in different forms of cancer and neurological abnormalities. As cancer development processes seem to be originated in stem cells, we have chosen to examine the effects of sodium arsenite on signaling pathways and the corresponding transcription factors that regulate cell viability and self-renewal in mouse embryonic stem cells (ESC) and mouse neural stem/precursor cells. We demonstrated that the crucial signaling pathway, which was substantially suppressed by sodium arsenite exposure (4 ?M) in ESC, was the PI3K-AKT pathway linked with numerous downstream targets that control cell survival and apoptosis. Furthermore, the whole core transcription factor circuitry that control self-renewal of mouse ESC (Stat3-P-Tyr705, Oct4, Sox2 and Nanog) was strongly down-regulated by sodium arsenite (4 ?M) exposure. This was followed by G2/M arrest and induction of the mitochondrial apoptotic pathway that might be suppressed by caspase-9 and caspase-3 inhibitors. In contrast to mouse ESC with very low endogenous IL6, mouse neural stem/precursor cells (C17.2 clone immortalized by v-myc) with high endogenous production of IL6 exhibited a strong resistance to cytotoxic effects of sodium arsenite that could be decreased by inhibitory anti-IL6 antibody or Stat3 inhibition. In summary, our data demonstrated suppression of self-renewal and induction of apoptosis in mouse ESC by sodium arsenite exposure, which was further accelerated due to simultaneous inhibition of the protective PI3K-AKT and Stat3-dependent pathways.",
Arsenic,1247805,"Sodium arsenite down-regulates the expression of X-linked inhibitor of apoptosis protein via translational and post-translational mechanisms in hepatocellular carcinoma Abstract: X-linked inhibitor of apoptosis protein (XIAP) is a member of the inhibitors of apoptosis protein (IAP) family, and has been reported to exhibit elevated expression levels in hepatocellular carcinoma (HCC) and promote cell survival, metastasis and tumor recurrence. Targeting XIAP has proven effective for the inhibition of cancer cell proliferation and restoration of cancer cell chemosensitivity. Arsenic (or sodium arsenite) is a potent anti-tumor agent used to treat patients with acute promyelocytic leukemia (APL). Additionally, arsenic induces cell growth inhibition, cell cycle arrest and apoptosis in human HCC cells. In this study, we identified XIAP as a target for sodium arsenite-induced cytotoxicity in HCC. The exposure of HCC cell lines to sodium arsenite resulted in inhibition of XIAP expression in both a dose- and time-dependent manner. Sodium arsenite blocked the de novo XIAP synthesis and the activity of its internal ribosome entry site (IRES) element. Moreover, treatment with sodium arsenite decreased the protein stability of XIAP and induced its ubiquitin-proteasomal degradation. Overexpression of XIAP attenuated the pro-apoptotic effect of sodium arsenite in HCC. Taken together, our data demonstrate that sodium arsenite suppresses XIAP expression via translational and post-translational mechanisms in HCC.",
Arsenic,656662,"Activation of Hedgehog signaling by the environmental toxicant arsenic may contribute to the etiology of arsenic-induced tumors Abstract: Exposure to the environmental toxicant arsenic, through both contaminated water and food, contributes to significant health problems worldwide. In particular, arsenic exposure is thought to function as a carcinogen for lung, skin, and bladder cancer via mechanisms that remain largely unknown. More recently, the Hedgehog signaling pathway has also been implicated in the progression and maintenance of these same cancers. Based on these similarities, we tested the hypothesis that arsenic may act in part through activating Hedgehog signaling. Here, we show that arsenic is able to activate Hedgehog signaling in several primary and established tissue culture cells as well as in vivo. Arsenic activates Hedgehog signaling by decreasing the stability of the repressor form of GLI3, one of the transcription factors that ultimately regulate Hedgehog activity. We also show, using tumor samples from a cohort of bladder cancer patients, that high levels of arsenic exposure are associated with high levels of Hedgehog activity. Given the important role Hedgehog signaling plays in the maintenance and progression of a variety of tumors, including bladder cancer, these results suggest that arsenic exposure may in part promote cancer through the activation of Hedgehog signaling. Thus, we provide an important insight into the etiology of arsenic-induced human carcinogenesis, which may be relevant to millions of people exposed to high levels of arsenic worldwide.",
Arsenic,1348081,Immunoassay by Hydride Generation-Atomic Fluorescence Spectrometer Using Arsenic Absorbed Fe(3)O(4)@Au Nanoparticles as Label Abstract: ,
Arsenic,1348432,"Arsenic in the Muteh gold mining district, Isfahan, Iran Abstract: ",
Arsenic,1032700,"Effect of cycloheximide or puromycin on induction of thermotolerance by sodium arsenite in Chinese hamster ovary cells: involvement of heat shock proteins Abstract: After sodium arsenite (100 microM) treatment, the synthesis of three major heat shock protein families (HSPs; Mr = 110,000, 87,000, and 70,000), as studied with one-dimensional gels, was enhanced twofold relative to that of unheated cells. The increase of unique HSPs, if studied with two-dimensional gels, would probably be much greater. In parallel, thermotolerance was observed as a 100,000-fold increase in survival from 10(-6) to 10(-1) after 4 hr at 43 degrees C, and as a thermotolerance ratio (TTR) of 2-3 at 10(-3) isosurvival for heating at 45.5 degrees C. Cycloheximide (CHM: 10 micrograms/ml) or puromycin (PUR: 100 micrograms/ml), which inhibited total protein synthesis and HSP synthesis by 95%, completely suppressed the development of thermotolerance when either drug was added after sodium arsenite treatment and removed prior to the subsequent heat treatment. Therefore, thermotolerance induced by arsenite treatment correlated with an increase in newly synthesized HSPs. However, with or without arsenite treatment, CHM or PUR added 2-6 hr before heating and left on during heating caused a 10,000-100,000-fold enhancement of survival when cells were heated at 43 degrees C for 4 hr, even though very little synthesis of heat shock proteins occurred. Moreover, these cells manifesting resistance to heating at 43 degrees C after CHM treatment were much different than those manifesting resistance to 43 degrees C after arsenite treatment. Arsenite-treated cells showed a great deal of thermotolerance (TTR of about 10) when they were heated at 45 degrees C after 5 hr of heating at 43 degrees C, compared with less thermotolerance (TTR of about 2) for the CHM-treated cells heated at 45 degrees C after 5 hr of heating at 43 degrees C. Therefore, there are two different phenomena. The first is thermotolerance after arsenite treatment (observed at 43 degrees C or 45.5 degrees C) that apparently requires synthesis of HSPs. The second is resistance to heat after CHM or PUR treatment before and during heating (observed at 43 degrees C with little resistance at 45.5 degrees C) that apparently does not require synthesis of HSPs. This phenomenon not requiring the synthesis of HSPs also was observed by the large increase in thermotolerance to 45 degrees C caused by heating at 43 degrees C, with or without CHM, after cells were incubated for 6 hr following arsenite pretreatment. For both phenomena, a model based on synthesis and redistribution of HSPs is presented.",
Arsenic,2149146,"Trypanosoma brucei aquaglyceroporin 2 is a high-affinity transporter for pentamidine and melaminophenyl arsenic drugs and the main genetic determinant of resistance to these drugs Abstract: <strong>OBJECTIVES: </strong>Trypanosoma brucei drug transporters include the TbAT1/P2 aminopurine transporter and the high-affinity pentamidine transporter (HAPT1), but the genetic identity of HAPT1 is unknown. We recently reported that loss of T. brucei aquaglyceroporin 2 (TbAQP2) caused melarsoprol/pentamidine cross-resistance (MPXR) in these parasites and the current study aims to delineate the mechanism by which this occurs.<br /><br /><strong>METHODS: </strong>The TbAQP2 loci of isogenic pairs of drug-susceptible and MPXR strains of T. brucei subspecies were sequenced. Drug susceptibility profiles of trypanosome strains were correlated with expression of mutated TbAQP2 alleles. Pentamidine transport was studied in T. brucei subspecies expressing TbAQP2 variants.<br /><br /><strong>RESULTS: </strong>All MPXR strains examined contained TbAQP2 deletions or rearrangements, regardless of whether the strains were originally adapted in vitro or in vivo to arsenicals or to pentamidine. The MPXR strains and AQP2 knockout strains had lost HAPT1 activity. Reintroduction of TbAQP2 in MPXR trypanosomes restored susceptibility to the drugs and reinstated HAPT1 activity, but did not change the activity of TbAT1/P2. Expression of TbAQP2 sensitized Leishmania mexicana promastigotes 40-fold to pentamidine and &gt;1000-fold to melaminophenyl arsenicals and induced a high-affinity pentamidine transport activity indistinguishable from HAPT1 by Km and inhibitor profile. Grafting the TbAQP2 selectivity filter amino acid residues onto a chimeric allele of AQP2 and AQP3 partly restored susceptibility to pentamidine and an arsenical.<br /><br /><strong>CONCLUSIONS: </strong>TbAQP2 mediates high-affinity uptake of pentamidine and melaminophenyl arsenicals in trypanosomes and TbAQP2 encodes the previously reported HAPT1 activity. This finding establishes TbAQP2 as an important drug transporter.",
Arsenic,628214,"Urothelial cytotoxicity and regeneration induced by dimethylarsinic acid in rats Abstract: Inorganic arsenic is a known human carcinogen of the skin and respiratory tract. Epidemiologic evidence indicates that it is also carcinogenic to the urinary bladder and other internal organs. Lack of an animal model has limited progress on understanding the mechanism of arsenic carcinogenesis. It was recently reported that high doses of an organic arsenical, dimethylarsinic acid (DMA), increased urinary bladder tumors in rats when administered in the diet or in the drinking water for 2 years, with the female being more sensitive than the male. We previously showed that high doses of DMA (40 or 100 ppm of the diet) fed for 10 weeks increased urothelial cell proliferation in the rat. Treatment with DMA also increased renal calcification and increased urinary calcium concentration. In 2 experiments, we examined the urothelial proliferative effects of treatment with 100 ppm DMA in the diet in female F344 rats for 2 and 10 weeks and for 6 and 24 h, and 3, 7, and 14 days. Cytotoxic changes in the urothelium were evident by SEM as early as 6 h after treatment was begun. Foci of cellular necrosis were detected after 3 days of treatment, followed by widespread necrosis of the urothelium after 7 days of treatment. The bromodeoxyuridine (BrdU) labeling index was not increased until after 7 days of treatment, suggesting that administration of DMA results in cytotoxicity with necrosis, followed by regenerative hyperplasia of the bladder epithelium. Although the rat provides an animal model to study the urothelial effects of DMA, the relevance of this finding to inorganic arsenic carcinogenesis in humans must be extrapolated cautiously, due to the high doses of DMA necessary to produce these changes in the rat and the differences in metabolism of arsenicals in rodents, especially rats, compared to humans.",
Arsenic,2088320,"An appraisal of groundwater quality for drinking and irrigation purposes in southern part of Bathinda district of Punjab, northwest India Abstract: Groundwater is being used for drinking and irrigation purposes in the agricultural dominated Indian state of Punjab. Fifty-six groundwater samples were collected from Bathinda, a south-western district of Punjab, during the pre-monsoon (March 2010) and post-monsoon (October 2011) seasons. These samples were tested for major cations, anions and contaminants. Various classification systems were used to study the groundwater quality with respect to drinking as well as irrigation purposes. Total dissolved solids (TDS) and total hardness (TH) are generally used to determine the suitability of groundwater for drinking purpose. Considering TDS as a parameter, 54 and 57 % groundwater samples were found to be unsuitable for use during the pre- and post-monsoon seasons. A wide range of TH values were observed in the pre-monsoon and post-monsoon waters samples (mean 250 and 270 mgL(-1)). About 75 % of pre-monsoon and 79 % of post-monsoon samples exceeded the maximum permissible limit (MPL) of TH (150 mg L-1) proposed by WHO. In terms of contaminant ions, 40 % and 55 % of the pre- and post-monsoon water samples were unfit for drinking purposes w.r.t. fluoride (MPL 1.5 mg F L-1), 29 and 36 % were unfit w.r.t arsenic (MPL 10 mu g L-1) and 33 and 45 % were unfit w.r.t nitrate (MPL 45 mg NO3 (-) L-1), respectively. To determine the suitability of groundwater of Bathinda for irrigation purpose, three classification systems proposed by different research workers were used. The parameters electrical conductivity (EC), sodium adsorption ratio, and residual sodium carbonate (RSC) were calculated on the basis of chemical data. Considering EC and RSC together, 32 % samples collected during pre-monsoon season were fit, 19 % were marginal and 49 % were unfit for use. However, during post-monsoon, samples fit for irrigation decreased to 17 % and samples unfit for irrigation increased to 70 %. Increases in the percentage of unfit samples for irrigation after monsoon indicates addition of salts along with the rain water percolated into the groundwater. The other two classification systems, i.e. US Salinity diagram and Wilcox diagram also showed the similar results.",
Arsenic,2337264,"Shallow hydrostratigraphy in an arsenic affected region of Bengal Basin: Implication for targeting safe aquifers for drinking water supply Abstract: To delineate arsenic (As) safe aquifer(s) within shallow depth, the present study has investigated the shallow hydrostratigraphic framework over an area of 100km(2) at Chakdaha Block of Nadia District, West Bengal. Drilling of 29 boreholes and subsequent hydrostratigraphic modeling has identified three types of aquifer within 50m below ground level (bgl). Aquifer-1 represents a thick paleochannel sequence, deposited parallel to the River Hooghly and Ichamati. Aquifer-2 is formed locally within the overbank deposits in the central floodplain area and its vertical extension is strictly limited to 25m bgl. Aquifer-3 is distributed underneath the overbank deposits and represents an interfluvial aquifer of the area. Aquifer-3 is of Pleistocene age (~70ka), while aquifer-1 and 2 represent the Holocene deposits (age &lt;9.51ka), indicating that there was a major hiatus in the sediment deposition after depositing the aquifer-3. Over the area, aquifer-3 is markedly separated from the overlying Holocene deposits by successive upward sequences of brown and olive to pale blue impervious clay layers. The groundwater quality is very much similar in aquifer-1 and 2, where the concentration of As and Fe very commonly exceeds 10?g/L and 5mg/L, respectively. Based on similar sediment color, these two aquifers have jointly been designated as the gray sand aquifer (GSA), which constitutes 40% (1.84×10(9)m(3)) of the total drilled volume (4.65×10(9)m(3)). In aquifer-3, the concentration of As and Fe is very low, mostly &lt;2?g/L and 1mg/L, respectively. This aquifer has been designated as the brown sand aquifer (BSA) according to color of the aquifer materials and represents 10% (4.8×10(8)m(3)) of the total drilled volume. This study further documents that though the concentration of As is very low at BSA, the concentration of Mn often exceeds the drinking water guidelines.",
Arsenic,1936081,"Release of arsenic to deep groundwater in the Mekong Delta, Vietnam, linked to pumping-induced land subsidence Abstract: Deep aquifers in South and Southeast Asia are increasingly exploited as presumed sources of pathogen- and arsenic-free water, although little is known of the processes that may compromise their long-term viability. We analyze a large area (&gt;1,000 km(2)) of the Mekong Delta, Vietnam, in which arsenic is found pervasively in deep, Pliocene-Miocene-age aquifers, where nearly 900 wells at depths of 200-500 m are contaminated. There, intensive groundwater extraction is causing land subsidence of up to 3 cm/y as measured using satellite-based radar images from 2007 to 2010 and consistent with transient 3D aquifer simulations showing similar subsidence rates and total subsidence of up to 27 cm since 1988. We propose a previously unrecognized mechanism in which deep groundwater extraction is causing interbedded clays to compact and expel water containing dissolved arsenic or arsenic-mobilizing solutes (e.g., dissolved organic carbon and competing ions) to deep aquifers over decades. The implication for the broader Mekong Delta region, and potentially others like it across Asia, is that deep, untreated groundwater will not necessarily remain a safe source of drinking water.",
Arsenic,1018493,"The tumor promoter arsenite stimulates AP-1 activity by inhibiting a JNK phosphatase Abstract: Trivalent arsenic (As3+) is highly carcinogenic, but devoid of known mutagenic activity. Therefore, it is likely to act as a tumor promoter. To understand the molecular basis for the tumor-promoting activity of As3+, we examined its effect on transcription factor AP-1, whose activity is stimulated by several other tumor promoters. We found that As3+, but not As5+, which is toxic but not carcinogenic, is a potent stimulator of AP-1 transcriptional activity and an efficient inducer of c-fos and c-jun gene expression. Induction of c-jun and c-fos transcription by As3+ correlates with activation of Jun kinases (JNKs) and p38/Mpk2, which phosphorylate transcription factors that activate these immediate early genes. No effect on ERK activity was observed. As5+, on the other hand, had a negligible effect on JNK or p38/Mpk2 activity. Biochemical analysis and co-transfection experiments strongly suggest that the primary mechanism by which As3+ stimulates JNK activity involves the inhibition of a constitutive dual-specificity JNK phosphatase. This phosphatase activity appears to be responsible for maintaining low basal JNK activity in non-stimulated cells and its inhibition may lead to tumor promotion through induction of proto-oncogenes such as c-jun and c-fos, and stimulation of AP-1 activity. The same phosphatase may also regulate p38/Mpk2 activity.",
Arsenic,2337070,"Contamination of water and soil by the Erdenet copper-molybdenum mine in Mongolia Abstract: As one of the largest copper-molybdenum (Cu-Mo) mines in the world, the Erdenet Mine in Mongolia has been active since 1978 and is expected to continue operations for at least another 30 years. In this study, the potential impacts of mining activities on the soil and water environments have been evaluated. Water samples showed high concentrations of sulfate, calcium, magnesium, Mo, and arsenic, and high pH values in the order of high to low as follows: tailing water > Khangal River > groundwater. Statistical analysis and the delta H-2 and delta O-18 values of water samples indicate that the tailing water directly affects the stream water and indirectly affects groundwater through recharge processes. Soil and stream sediments are highly contaminated with Cu and Mo, which are major elements of ore minerals. Based on the contamination factor (CF), the pollution load index (PLI), and the degree of contamination (C-d), soil appears to be less contaminated than stream sediments. The soil particle size is similar to that of tailing materials, but stream sediments have much coarser particles, implying that the materials have different origins. Contamination levels in stream sediments display a tendency to decrease with distance from the mine, but no such changes are found in soil. Consequently, soil contamination by metals is attributable to wind-blown dusts from the tailing materials, and stream sediment contamination is caused by discharges from uncontained subgrade ore stock materials. Considering the evident impact on the soil and water environment, and the human health risk from the Erdenet Mine, measures to mitigate its environmental impact should be taken immediately including source control, the establishment of a systematic and continuous monitoring system, and a comprehensive risk assessment.",
Arsenic,2337286,"Vibrational spectroscopy of the multianion mineral gartrellite from the Anticline Deposit, Ashburton Downs, Western Australia Abstract: The multianion mineral gartrellite PbCu(Fe(3+),Cu)(AsO4)2(OH,H2O)2 has been studied by a combination of Raman and infrared spectroscopy. The molecular structure of gartrellite is assessed. Gartrellite is one of the tsumcorite mineral group based upon arsenate and/or sulphate anions. Crystal symmetry is either triclinic in the case of an ordered occupation of two cationic sites, triclinic due to ordering of the H bonds in the case of species with two water molecules per formula unit, or monoclinic in the other cases. Characteristic Raman spectra of the mineral gartrellite enable the assignment of the bands to specific vibrational modes. These spectra are related to the structure of gartrellite. The position of the hydroxyl and water stretching vibrations are related to the strength of the hydrogen bond formed between the OH unit and the AsO4(3-) anion.",
Arsenic,1343896,"A 19F nuclear magnetic resonance and Raman spectroscopic investigation of the reaction of iodine oxide pentafluoride with the Lewis acids, antimony and arsenic pentafluoride Abstract: The reactions of IOF5 with SbF5 and with AsF5 have been investigated at low temperature by 19F nmr and Raman spectroscopy. It was found that SbF5 forms labile 1:1 and 2:1 complexes whereas AsF5 forms only a 1:1 complex. The IOF5 is bound through its oxygen atom to the Lewis acids AsF5, SbF5, or (SbF5)2.",
Arsenic,1248000,"Superoxide dismutase protects cells from DNA damage induced by trivalent methylated arsenicals Abstract: Superoxide dismutase (SOD) catalyzes the conversion of superoxide to hydrogen peroxide. Heterozygous mice of strain B6;129S7-Sod1(tm1Leb)/J were obtained from Jackson Laboratories and bred to produce offspring that were heterozygous (+/Sod1(tm1Leb)), homozygous wild-type (+/+), and homozygous knockout (Sod1(tm1Leb) /Sod1(tm1Leb)) for the Cu/Zn superoxide dismutase (Sod1) gene. Splenocytes from these mice were exposed to several concentrations of either sodium arsenite (As3 [0-200 ?M]), monomethylarsonous acid (MMA3 [0-10 ?M]), or dimethylarsinous acid (DMA3 [0-10 ?M]) for 2 hr. Cells were then examined for DNA damage using the alkaline single cell gel electrophoresis assay. Methyl methanesulfonate (MMS) was used as a positive control. Splenocytes from each of the three genotypes for Sod1 were equally sensitive to MMS and As3. However, at equimolar concentrations, DMA3 and MMA3 produced significantly more DNA damage in the homozygous knockout mouse splenocytes than in the splenocytes from the wild-type or heterozygous mice. These findings suggest that superoxide is involved either directly or indirectly in producing DNA damage in cells exposed to trivalent methylated arsenicals. These arsenicals may generate reactive oxygen species that damage DNA. This DNA damage may be a key factor in initiating cancer in vivo.",
Arsenic,2278412,"Lotus roots accumulate heavy metals independently from soil in main production regions of China Abstract: The global issue of heavy metal pollution causes concern on lotus root, a popular aquatic vegetable grown in sludge supposedly heavily contaminated. The relevance of heavy metals in soil and lotus roots in production remains unclear. In this work, four heavy metals, lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As), in lotus roots and ambient soil from main production areas of China were determined. The bioconcentration factor (BCF) of each heavy metal and correlation coefficient among heavy metals in soil and lotus roots were analyzed. Red soil (pH 6-7) in one location exceeded the maximum allowable limit of Cd by 91%, while soils in seven locations met the environmental requirements for producing safe lotus roots, including three red soils (pH 4-5), two moisture soils (pH 4-7), one cinnamon soil (pH 6-7), and one paddy soil (pH 6-7). Lotus roots were individually contaminated with Pb in two locations (red soil and paddy soil),As in two locations (red soil and cinnamon soil), and Hg in one location (red soil), exceeding the maximum allowable limit by 3-16%. Heavy metal levels of lotus roots produced in all investigated areas still met the safety standard as indicated by integrative pollution indexes (IPI). However, the close-to-limit IPI will certainly raise the safety concern for lotus root production. BCF of heavy metals decreased in an order of Cd (5.03-46.67%), Hg (2.42-7.20%), As (1.93-6.68%) and Pb (0.02-1.82%), showing lotus root's ability to accumulate metals varied with metal types. BCF and correlation coefficient showed that the lotus roots tended to accumulate heavy metals less efficiently from soil with higher levels of heavy metals, and vice versa. Heavy metal levels were positively correlated in soil but largely irrelevant in lotus roots. Thus, heavy metals in lotus roots were accumulated primarily independently from or partially negatively correlated with soil, complicating the enrichment mechanism of heavy metals in lotus roots. The possible causes of soil independent accumulation of heavy metals in lotus roots are discussed. (C) 2013 Elsevier B.V. All rights reserved.",
Arsenic,601313,"Inhibition by methylated organoarsenicals of the respiratory 2-oxo-acid dehydrogenases Abstract: Abstract: Inorganic arsenic that is ingested through drinking water or inhalation is metabolized by biological methylation pathways into organoarsenical metabolites. It is now becoming understood that this metabolism that was formerly considered to be detoxification may contribute as much or more to increasing the toxicity of arsenic. One proposed mode of the toxic action of arsenic and its organoarsenic metabolites is through its binding to proteins and inactivating their enzymatic activity. The classic case has been considered the affinity of the proximal 1,3 sulfhydryl groups of the lipoic acid cofactor of the pyruvate dehydrogenase complex for arsenic. A 2:1 stoichiometry of sulfhydryl to arsenic groups has been measured in proteins and arsenical complexes can be synthesized using free d,l-lipoic acid. The relative importance of this site for arsenic binding has come in to question through the use of methylating bifunctional arsenic complexes, and the suggestion that arsenic inhibits the pyruvate dehydrogenase complex indirectly by elevating mitochondrial hydrogen peroxide generation. In order to separate the effects of direct trivalent arsenite toxicity from that of hydrogen peroxide and activated oxygen, we studied the inhibition of the PDH complex under conditions that did not generate hydrogen peroxide but did expose the lipoic acid group in its reduced state to arsenicals. We also studied the effects of arsenicals in the inhibition of the ÃŽÂ±-ketoglutarate dehydrogenase complex. We found that only trivalent arsenical compounds inhibited the activity of both dehydrogenase complexes and only when the lipoic acid was in its reduced form. Arsenite inhibited both enzyme complexes approximately equivalently while monomethylarsenite inhibited the PDH complex to a greater extent than the KGDH complex Ã¢â‚¬â€œ although both complexes were very sensitive to inhibition by this complex. Dimethylarsenite inhibition of both complexes was only observed with longer ... [Copyright 2009 Elsevier] Copyright of Journal of Organometallic Chemistry is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1025939,"Synergistic neurotoxic effects of arsenic and dopamine in human dopaminergic neuroblastoma SH-SY5Y cells Abstract: Parkinson's disease is an environmentally influenced, neurodegenerative disease of unknown origin that is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta of the brain. Arsenic is an environmental contaminant found naturally in ground water, industrial waste, and fertilizers. The initial goal of the present study was to determine if a mixture of arsenite (As(+3)) and dopamine (DA) could cause enhanced degeneration of dopaminergic neuronal cells. Additional goals were to determine the mechanism (apoptosis or necrosis) of As- and DA-induced cell death and if death could be attenuated by antioxidants. The cell culture model employed was the SH-SY5Y neuroblastoma cell line that has been shown to possess differentiated characteristics of dopaminergic neurons. The results demonstrated that a mixture of As(+3) and DA was synergistic in producing the death of the SH-SY5Y cells when compared with exposure to either agent alone. A mixture of 10muM As(+3) and 100muM DA produced almost a complete loss of cell viability over a 24-h period of exposure, whereas, each agent alone had minimal toxicity. It was shown that necrosis, and not apoptosis, was the mechanism of cell death produced by exposure of the SH-SY5Y cells to the mixture of As(+3) and DA. It was also demonstrated that the antioxidants, N-acetylcysteine, and Sulforaphane, attenuated the toxicity of the mixture of As(+3) and DA to the SH-SY5Y cells. This study provides initial evidence that As(+3) and DA synergistically can cause enhanced toxicity in cultured neuronal cells possessing dopaminergic differentiation.",
Arsenic,2215692,"A consecutive study on arsenic exposure and intelligence quotient (IQ) of children in Bangladesh Abstract: <strong>OBJECTIVE: </strong>In a recent cross-sectional investigation, we reported the intellectual function of adolescents (aged 14 and 15 years) in Bangladesh who had been exposed to arsenic (As). Here, we report a consecutive investigation on the intelligence quotient (IQ) of 408 children who are living in the Sonargoan Thana of Bangladesh (two age groups: 9 and 10 years; 4 and 5 years) were exposed to high levels of As in the groundwater.<br /><br /><strong>METHODS: </strong>Urine and water samples were collected to assess As exposure. The IQ of the children was estimated using the Raven's Standard Progressive Matrices and the Kaufman Brief Intelligence Test. Information on parents' socioeconomic status (SES) was collected as confounding factors.<br /><br /><strong>RESULTS: </strong>The results indicate that As exposure was responsible for a lower IQ. The concentration of urinary As ([As]u) was associated with reduced intellectual function in a dose-response manner. A stronger association was found between reduced intellectual function (IQ) and [As]u than the level of As in the drinking water [As]w. There was no association between verbal IQ scores and [As]u of children in early childhood (aged 4 and 5 years).<br /><br /><strong>CONCLUSION: </strong>Based on these results, we conclude that current levels of As in the urine ([As]u), which we considered to reflect recent exposure to As from all possible sources, including groundwater, food, among others, were negatively associated to the IQ of the children tested, and that this adverse effect of As may also gradually accumulate over time among the poor.",
Arsenic,710909,"Effects of folate on arsenic toxicity in Chang human hepatocytes: involvement of folate antioxidant properties Abstract: We investigated the effects and modes of action of the nutritional factor folate on arsenic-induced toxicity in Chang human hepatocytes. Cells were cultured in folate-deficient medium, normal folate medium or folate-supplemented medium for 1h and then co-treated with or without 20-microM sodium arsenite (NaAsO(2)) for 24h. The results showed that folate deficiency significantly aggravated the NaAsO(2)-induced apoptotic progression [evidenced by phosphatidylserine externalization, cleavage of caspase-3 and poly (ADP-ribose) polymerase (PARP), collapse of mitochondrial potential, and release of cytochrome c from the mitochondria] and decrease of cell viability. Folate supplementation significantly attenuated all the above mentioned NaAsO(2)-induced effects except phosphatidylserine externalization. The NaAsO(2)-induced generation of intracellular reactive oxygen species and malondialdehyde was aggravated, to some extent, by folate deficiency, but these phenomena were significantly suppressed by folate supplementation. In contrast, NaAsO(2)-induced elevation of reduced glutathione levels was significantly suppressed by folate deficiency, but significantly enhanced by folate supplementation. In addition, folate deficiency significantly decreased the arsenic methylation capacity of the hepatocytes, but had no effects on cellular retention of arsenic. Folate supplementation had no significant effect on cellular retention or methylation of arsenic. These results indicate that folate deficiency aggravates arsenic-induced toxicity and apoptosis, while folate supplementation attenuates these effects. Folate, which plays a role in arsenic metabolism, also exerts its effect on arsenic toxicity at least partly because of its antioxidant property.",
Arsenic,1704111,"Toxicity, transformation and accumulation of inorganic arsenic species in a microalga Scenedesmus sp isolated from soil Abstract: Arsenic speciation and cycling in the natural environment are highly impacted via biological processes. Since arsenic is ubiquitous in the environment, microorganisms have developed resistance mechanisms and detoxification pathways to overcome the arsenic toxicity. This study has evaluated the toxicity, transformation and accumulation of arsenic in a soil microalga Scenedesmus sp. The alga showed high tolerance to arsenite. The 72-h 50 % growth inhibitory concentrations (IC50 values) of the alga exposed to arsenite and arsenate in low-phosphate growth medium were 196.5 and 20.6 mg? L?1, respectively. When treated with up to 7.5 mg? L?1 arsenite, Scenedesmus sp. oxidised all arsenite to arsenate in solution. However, only 50 % of the total arsenic remained in the solution while the rest was accumulated in the cells. Thus, this alga has accumulated arsenic as much as 606 and 761 ?g? g?1 dry weight when exposed to 750 ?g? L?1 arsenite and arsenate, respectively, for 8 days. To our knowledge, this is the first report of biotransformation of arsenic by a soil alga. The ability of this alga to oxidise arsenite and accumulate arsenic could be used in bioremediation of arsenic from contaminated water and soil.",
Arsenic,64075,"Increased prevalence of hypertension and long-term arsenic exposure Abstract: To examine the association between long-term exposure to inorganic arsenic and the prevalence of hypertension, we studied a total of 382 men and 516 women residing in villages where arseniasis was hyperendemic. Hypertension was defined as a systolic blood pressure of 160 mm Hg or greater, a diastolic blood pressure of 95 mm Hg or greater, or a history of hypertension treated regularly with antihypertensive drugs. The long-term arsenic exposure was calculated from the history of artesian well water consumption obtained through standardized interviews based on a structured questionnaire and the measured arsenic concentration in well water. Residents in villages where long-term arseniasis was hyperendemic had a 1.5-fold increase in age- and sex-adjusted prevalence of hypertension compared with residents in nonendemic areas. Duration of artesian well water consumption, average arsenic concentration in drinking water, and cumulative arsenic exposure were all significantly associated with hypertension prevalence. The higher the cumulative arsenic exposure, the higher the prevalence of hypertension. This dose-response relation remained significant after adjustment for age, sex, diabetes mellitus, proteinuria, body mass index, and serum triglyceride level. The results suggest that long-term arsenic exposure may induce hypertension in humans.",
Arsenic,1356877,"Use Of Genomics Data To Predict Mode Of Action In Chemical Hazard Characterization Abstract: The process of characterization of chemical hazard and human carcinogenic potential is evolving from their traditional dependence on tumor endpoints to the inclusion of data that describe the mode of action (MOA) at the cellular and molecular level. Information from gene expression profiling has the potential to greatly improve this process by predicting key mechanistic pathways involved in the chemical mode of toxicity and the human relevancy of the effects observed in animals by parallel inter-species comparisons. Hypothetical MOA(s) can then be generated for a more targeted testing protocol of the chemical of concern. Dimethylarsinic acid (DMA) will be used as an example to illustrate how gene microarray data can more rapidly provide mechanistic information comparable to that developed from years of research using more traditional toxicological endpoints. Exposure to DMA has been shown to result in rat urinary bladder tumors. Studies specifically designed to evaluate the mode of action for these bladder tumors suggest that DMA-induced cancer is associated with increased cell proliferation, generation of reactive oxygen species and cytotoxicity. Gene expression analysis of the target cell population for bladder cancer after in vivo exposure characterized the molecular changes involved in DMA-induced toxicity and demonstrated that oxidative stress response, cell proliferation and apoptosis are all involved in the toxicity response. The present example shows how genomics can be used as a cost- and time-effective tool to inform MOA and to generate hypothesis-driven and targeted chemical testing procedures for improved human health risk assessments.",
Arsenic,1340244,"A Pilot Study of Darbepoetin Alfa for Prophylactic Neuroprotection in Aortic Surgery Abstract: BACKGROUND: Descending aortic (DA) surgery poses a high risk for spinal and cerebral infarction and routine use of lumbar drains allows for measurement of CSF markers of neurologic injury. Erythropoiesis medications have extensive preclinical data demonstrating neuroprotection. We hypothesized that prophylactic darbepoetin alfa (DARB) given before surgery reduces neurologic injury in patients undergoing DA repair. METHODS AND RESULTS: We performed a prospective adaptive dose-finding trial of prophylactic DARB ( www.clinicaltrials.gov NCT00647998) that terminated prematurely following publication of an erythropoietin stroke study showing possible harm. Enrollment halted before dose adjustments; nine patients each received 1 mg/kg IV DARB immediately before surgery. A prospective cohort of nine untreated patients was subsequently obtained for comparison. The primary outcome of death or neurologic impairment at discharge occurred in 1/9 (11 %) DARB patients and 3/9 (33 %) controls (p = 0.58). There were no statistical differences in changes of CSF biomarkers from baseline to 48 h comparing DARB patients to controls: S100?, median 214 versus 260 ng/ml (p = 0.69); glial fibrillary acidic protein (GFAP), median 0.022 versus 0.58 ng/ml (p = 0.45). In patients with early perioperative neurologic ischemia, there were greater changes in CSF biomarkers, compared to those without ischemia: S100?, median 2301 versus 124 ng/ml (p = 0.04); GFAP, median 31.78 versus 0.31 ng/ml (p = 0.34). CONCLUSIONS: There were no significant effects of prophylactic DARB on clinical outcome or CSF markers of neurologic injury in this pilot study, although all point estimates favored treatment. DA repair is a promising model of prophylactic neuroprotection.",
Arsenic,1936103,"The assessment of environmental pollution along the coast of Beibu Gulf, northern South China Sea: an integrated biomarker approach in the clam Meretrix meretrix Abstract: The clam Meretrix meretrix was used as a biomonitor to implement an environmental monitoring program along the coast of Beibu Gulf in October 2011. This program not only analyzed biomarkers including acetylcholinesterase, glutathione peroxidase, glutathione S-transferase, catalase and superoxide dismutase activities, total glutathione content and lipid peroxidation level in M. meretrix but also adopted a multi-biomarker approach - integrated biomarker response (IBR) to assess the environmental quality in this ecosystem. In addition, the metal (Hg, As, Cu, Pb, Zn, Cd and Cr) and polychlorinated biphenyls (PCBs) content in the surface sediment at the study area were also measured. The results showed that IBR index was able to distinguish a space trend between sampling sites with different degrees of anthropogenic environmental stress. Integrated contamination degree were displayed in the form of star plots and compared to IBR plots. There was a visual consistency between the pollution level and IBR variation. Based on the results, it was proved that the IBR method coupled with chemical analysis was quite useful for the assessment of environmental pollution in the coastal system.",
Arsenic,627010,"Inorganic arsenic exposure and type 2 diabetes mellitus in Mexico Abstract: Inorganic arsenic exposure in drinking water has been recently related to diabetes mellitus. To evaluate this relationship the authors conducted in 2003, a case-control study in an arseniasis-endemic region from Coahuila, a northern state of Mexico with a high incidence of diabetes. The present analysis includes 200 cases and 200 controls. Cases were obtained from a previous cross-sectional study conducted in that region. Diagnosis of diabetes was established following the American Diabetes Association criteria, with two fasting glucose values 126 mg/100 ml (7.0 mmol/l) or a history of diabetes treated with insulin or oral hypoglycemic agents. The next subject studied, subsequent to the identification of a case in the cross-sectional study was taken as control. Inorganic arsenic exposure was measured through total arsenic concentrations in urine, measured by hydride-generation atomic absorption spectrophotometry. Subjects with intermediate total arsenic concentration in urine (63.5–104 ?g/g creatinine) had two-fold higher risk of having diabetes (odds ratio=2.16; 95% confidence interval: 1.23, 3.79), but the risk was almost three times greater in subjects with higher concentrations of total arsenic in urine (odds ratio=2.84; 95% confidence interval: 1.64, 4.92). This data provides additional evidence that inorganic arsenic exposure may be diabetogenic.",
Arsenic,1936106,"Evaluation of some pollutant levels in environmental samples collected from the area of the new campus of Taif University Abstract: The levels of radioactivity and heavy metals in soil, plant and groundwater samples collected from the area of the new campus of Taif University, Saudi Arabia, and its neighbouring areas have been determined. High-resolution gamma-ray spectroscopy was used for radioactivity measurements, and inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of heavy metals. The means of (226)Ra, (228)Ra and (40)K concentrations in water samples collected from four wells were found to be 0.13 ± 0.03, 0.05 ± 0.03 and 1.3 ± 0.5 Bq l(-1), respectively. The means of (238)U, (226)Ra, (228)Ra ((232)Th for soil samples) and (40)K concentrations in wild plant and soil samples were found to be 3.7 ± 4.1, 8.8 ± 11.6, 3.8 ± 2.9 and 1025 ± 685, and 8.6 ± 3.4, 12.8 ± 3.4, 16.6 ± 7.1 and 618 ± 82 Bq kg(-1) dry weight (DW), respectively. The (137)Cs of artificial origin was also detected in soil samples with a mean concentration of 3.8 ± 2.2 Bq kg(-1) DW. Evaluating the results, it can be concluded that the concentrations of (238)U, (226)Ra, (232)Th and (40)K in soil samples fall within the world average. Furthermore, 19 trace and major elements in groundwater samples and 22 elements in soil and plant samples were determined. The sampling locations of soil can be classified into three groups (relatively high, medium and low polluted) according to their calculated metal pollution index using the contents of trace and major elements. A cluster analysis of the contents of radioactivity and trace element contents in soil samples shows the presence of two main distinct clusters of sampling locations.",
Arsenic,1356872,"Mechanism of arsenic peripheral neurotoxicity Abstract: Introduction:Peripheral arsenic neurotoxicity has been demonstrated clinically and in electrophysiological studies. The aim of this study is to investigate the mechanism of the peripheral neurotoxicity of As in rats, with special focus on interactions with axonal cytoskeletal proteins. Methods:Male Wistar rats (225-250g) were exposed to arsenite (NaAsO3) given as a single dose iv (0; 15 or 20 mg/kg) for 3, 6 or 9 hrs. Urine samples were collected for the duration of exposure namely 3, 6 or 9 hrs, whereafter the rats were sacrificed. Sciatic nerves (N. ischiadicus) were excised and cytoskeletal proteins were analysed with SDS-PAGE and Western blot. Arsenic in urine, blood and sciatic nerve was measured with AAS. Results: The amount of arsenic in urine of 15-mg/kg groups decreased in the 9-hour time course from 0.5 to 0.25 (mM As/mM creatinine). Blood arsenic content diminished from 2.3 to 1.58 mg/l in rats group receiving 15 mg/kg doses and reduction of 2.9 to 2.34 mg/l in rats group receiving 20 mg/kg doses. Arsenic was present in sciatic nerve but did not correlate with doses and/or duration of exposure. Biochemical analysis of N. ischiadicus revealed disappearance of neurofilament protein bands and fibroblasts in rats treated with the arsenite doses of 15 and 20 mg/kg. Few fibroblast protein bands disappeared in 20-mg/kg doses analyzed by SDS-PAGE. Some neurofilament proteins diminished in dose/effect manner measured in time and analyzed with western blot. Discussion: Arsenic affects the composition of cytoskeletal proteins in the rat sciatic nerve, especially the neurofilaments. The loss of these neurofilaments could explain the neurotoxicological effects.",
Arsenic,2215718,"Multivariate analysis of the heterogeneous geochemical processes controlling arsenic enrichment in a shallow groundwater system Abstract: The effects of various geochemical processes on arsenic enrichment in a high-arsenic aquifer at Jianghan Plain in Central China were investigated using multivariate models developed from combined adaptive neuro-fuzzy inference system (ANFIS) and multiple linear regression (MLR). The results indicated that the optimum variable group for the AFNIS model consisted of bicarbonate, ammonium, phosphorus, iron, manganese, fluorescence index, pH, and siderite saturation. These data suggest that reductive dissolution of iron/manganese oxides, phosphate-competitive adsorption, pH-dependent desorption, and siderite precipitation could integrally affect arsenic concentration. Analysis of the MLR models indicated that reductive dissolution of iron(III) was primarily responsible for arsenic mobilization in groundwaters with low arsenic concentration. By contrast, for groundwaters with high arsenic concentration (i.e., > 170 ?g/L), reductive dissolution of iron oxides approached a dynamic equilibrium. The desorption effects from phosphate-competitive adsorption and the increase in pH exhibited arsenic enrichment superior to that caused by iron(III) reductive dissolution as the groundwater chemistry evolved. The inhibition effect of siderite precipitation on arsenic mobilization was expected to exist in groundwater that was highly saturated with siderite. The results suggest an evolutionary dominance of specific geochemical process over other factors controlling arsenic concentration, which presented a heterogeneous distribution in aquifers.",
Arsenic,1016103,"Arsenic and fluoride induce neural progenitor cell apoptosis Abstract: The aim of the present study is to determine the effect of inorganic arsenic (As) and its metabolites on the viability of the neural progenitor cell (NPC) line C17.2, in order to evaluate cellular mechanisms involved in As developmental neurotoxicity. Moreover, we analyzed the effects of the coexposure to As and fluoride (F), a situation to which some populations are commonly exposed. Our results show that NPCs are not susceptible to pentavalent As species [arsenate, monomethylarsonic acid, and dimethylarsinic acid] and F alone. However, the trivalent metabolites of arsenate [arsenite, monomethylarsonous acid, and dimethylarsinous acid] are toxic at concentrations below 1 mg/l, and this susceptibility increases when there is coexposure with F (? 5 mg/l). Arsenite triggers apoptosis after 24 h of exposure, whereas monomethylarsonous acid produces necrosis at very short times (2 h). Arsenite leads to an increase in intracellular Ca levels and generation of reactive oxygen species, which may cause a decrease in mitochondrial transmembrane potential, release of cytochrome c, and consequent activation of caspases. A slight activation of calpain also takes place, which might favor activation of the mitochondrial pathway or might activate other pathways. The treatment with some antioxidants such as quercetin and ?-tocopherol shows only a partial reduction of the cytotoxicity.",
Arsenic,1251004,"Purification and characterization of a thermostable ?-galactosidase from Thielavia terrestris NRRL 8126 in solid state fermentation Abstract: Several seeds and husks of some plants belonging to leguminosae, Graminae, Compositae and Palmae were evaluated as carbon substrates to produce ?-galactosidase (?-Gal) by the thermophilic fungus, Thielavia terrestris NRRL 8126 in solid substrate fermentation. The results showed that Cicer arietinum (chick pea seed) was the best substrate for ?-Gal production. The crude enzyme was precipitated by ammonium sulphate (60%) and purified by gel filtration on sephadex G-100 followed by ion exchange chromatography on DEAE-Cellulose. The final purification fold of the enzyme was 30.42. The temperature and pH optima of purified ?-Gal from Thielavia terrestris were 70 °C and 6.5, respectively. The enzyme showed high thermal stability at 70 °C and 75 °C and the half-life of the ?-Gal at 90 °C was 45 min. Km of the purified enzyme was 1.31 mM. The purified enzyme was inhibited by Ag2+, Hg2+, Zn2+, Ba2+, Mg2+, Mn2+ and Fe2+ at 5 mM and 10 mM. Also, EDTA, sodium arsenate, L-cysteine and iodoacetate inhibited the enzyme activity. On the other hand, Ca2+, Cu2+, K+ and Na+ slightly enhanced the enzyme activity at 5 mM while at 10 mM they caused inhibition. The molecular weight of the ?-Gal was estimated to be 82 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This enzyme displays a number of biochemical properties that make it a potentially strong candidate for biotechnological and medicinal applications.",
Arsenic,1020334,"Promoting effects of monomethylarsonic acid, dimethylarsinic acid and trimethylarsine oxide on induction of rat liver preneoplastic glutathione S-transferase placental form positive foci: a possible reactive oxygen species mechanism Abstract: Dimethylarsinic acid (DMA) is a major metabolite of inorganic arsenicals, which are epidemiologically significant chemicals in relation to liver cancer in mammals. The present study was conducted to determine the promoting effects of organic arsenicals related to DMA [monomethylarsonic acid (MMA) and trimethylarsine oxide (TMAO)] on rat liver carcinogenesis using a liver medium-term bioassay (the Ito test). Male, 10-week-old, F344 rats were given a single i.p. injection of diethylnitrosamine at a dose of 200 mg/kg b.w. as an initiator. Starting 2 weeks thereafter they received 100 ppm of MMA, DMA or TMAO in their drinking water, or no supplement as a control, for 6 weeks. All animals underwent 2/3 partial hepatectomy in week 3 after initiation. Quantification of glutathione S-transferase placental form (GST-P)-positive foci as preneoplastic lesions in liver sections revealed significantly increased numbers and areas in all 3 treated groups compared with controls. Hepatic microsome cytochrome P-450 content was markedly increased with all 3 arsenic treatments. Markedly elevated CYP 2B1 protein levels and CYP 2B1/2 mRNA levels were thus observed in all cases. The potency of promotion was similar for MMA, DMA and TMAO. Since hydroxyradicals were found to be generated in the relatively early phase while methylated arsenicals were metabolized in liver, the resultant oxidative stress might have promoted lesion development.",
Arsenic,1337640,"Unique phenotypes in the sperm of the earthworm Eudrilus eugeniae for assessing radiation hazards Abstract: The earthworm, Eudrilus eugeniae is a segmented worm. It has two pairs of testes whose cells are highly proliferative. It was found that the earthworm, which is irradiated with X-ray, shows the following phenotypic changes in its sperm: fragmented acrosome in the head, break in the tail, and the appearance of zigzag sperm tail. Sperm morphology can be used as a tool to study radiation hazards in local areas. These three phenotypes were not observed in the sperm of worms exposed to different concentration of toxic chemicals such as sodium arsenate, lead acetate, and mercuric chloride. In contrast, exposure of worms to ethidium bromide caused fragmented acrosome in the head of their sperm cells.",
Arsenic,1347708,"Arsenic chemistry and remediation in Hawaiian soils Abstract: Past use of arsenical pesticides has resulted in elevated levels of arsenic (As) in some Hawaiian soils. Total As concentrations of 20-100 mg/kg are not uncommon, and can exceed 900 mg/kg in some lands formerly planted with sugarcane. With high contents of amorphous aluminosilicates and iron oxides in many Hawaii's volcanic ash-derived Andisols, a high proportion (25-30%) of soil As was associated with either these mineral phases or with organic matter. Less than 1% of the total As was water soluble or exchangeable. Furthermore, the soils can sorb As strongly: the addition of 1000 mg/kg as As (+5) resulted in only between 0.03 and 0.30 mg/L As in soil solution. In contrast, soils having more crystalline minerals (e.g., Oxisols) sorb less As and thus often contain less As. Phosphate fertilization increases As bioaccessibility, whereas the addition of Fe(OH)3 decreases it. Brake fern (Pteris vittata L.) can be used to remove some soil As. Concentrations of As in fronds varied on average from 60 mg/kg when grown on a low-As Oxisol to 350 mg/kg when grown on a high-As Andisol. Ratios of leaf As to CaCl2-extractable soil As were 12 and 222 for the Oxisol and Andisol, respectively.",
Arsenic,2088510,"Effect of Arsenic on Nitrosative Stress in Human Breast Cancer Cells and its Modulation by Flavonoids Abstract: Arsenic (As) is used in the treatment of leukaemia and breast cancer due to its strong oxidative cytotoxic action. However, it is also cytotoxic to normal cells. One proposed anticancer mechanism induced by As might be nitrosative stress (NS). Hence, it is believed that use of antioxidants such as flavonoids in combination with As might reduce its toxic action on normal cells without interfering with its antitumor action. In the present study, we evaluated the antineoplastic potential of As on breast human cancer lines MCF-7 and ZR-75-1 treated with redox-modulating flavonoids, such as quercetin (Q) and silymarin (S). It was noted that, even though both cell lines differed in their oxidative responsiveness, their viability was decreased by NS induction through ?-glutamyltranspeptidase inhibition. Arsenic triggered NS in both MCF-7 and ZR-75-1 cultures, with the formers being more sensitive without recovering their pre-treatment capacity. ZR-75-1 cells maintained their antioxidant status, whereas MCF-7 ones treated with S, As and As+Q did not. Silymarin did not interfere with the described As bioactivity. In summary, NS appears as an important anticancer mechanism exerted by As depending on the redox cellular response that could be differentially modified by dietary antioxidants. Hence, it is worthwhile to consider the use of dietary antioxidants as adjuvant in cancer chemotherapy, especially when using As.",
Arsenic,1337279,"Environmental arsenic contamination and its health effects in a historic gold mining area of the Mangalur greenstone belt of Northeastern Karnataka, India Abstract: This report summarizes recent findings of environmental arsenic (As) contamination and the consequent health effects in a community located near historic gold mining activities in the Mangalur greenstone belt of Karnataka, India. Arsenic contents in water, hair, nail, soil and food were measured by FI-HG-AAS. Elemental analyses of soils were determined by ICP-MS (inductively coupled plasma-mass spectrometry). Of 59 tube-well water samples, 79% had As above 10?gL(-1) (maximum 303?gL(-1)). Of 12 topsoil samples, six were found to contain As greater than 2000mgkg(-1) possibly indicating the impact of mine tailings on the area. All hair and nail samples collected from 171 residents contained elevated As. Arsenical skin lesions were observed among 58.6% of a total 181 screened individuals. Histopathological analysis of puncture biopsies of suspected arsenical dermatological symptoms confirmed the diagnosis in three out of four patients. Based on the time-course of As-like symptoms reported by the community as well as the presence of overt arsenicosis, it is hypothesized that the primary route of exposure in the study area was via contaminated groundwater; however, the identified high As content in residential soil could also be a significant source of As exposure via ingestion. Additional studies are required to determine the extent as well as the relative contribution of geologic and anthropogenic factors in environmental As contamination in the region. This study report is to our knowledge one of the first to describe overt arsenicosis in this region of Karnataka, India as well as more broadly an area with underlying greenstone geology and historic mining activity.",
Arsenic,1025157,"Arsenite alters global histone H3 methylation Abstract: Arsenic (As) is a well-characterized human carcinogen but is generally not mutagenic. The evidence that As induces both loss of global DNA methylation and gene promoter DNA hypermethylation has suggested that epigenetic mechanisms may play an important role in As-induced carcinogenesis. In the present study, we examined the change in histone methylation by As exposure. In human lung carcinoma A549 cells, exposure to inorganic trivalent As (arsenite) increased H3K9 dimethylation (H3K9me2) and decreased H3K27 trimethylation (H3K27me3), both of which represent gene silencing marks, while increasing the global levels of the H3K4 trimethylation (H3K4me3), a gene-activating mark. The increase in H3K9me2 was mediated by an increase in the histone methyltransferase G9a protein and messenger RNA levels. We also observed strikingly significant altered histone modifications induced by very low-dose (0.1 ?M) arsenite. Taken together, these results suggest a potential mechanism by which As induces carcinogenesis through the alteration of specific histone methylations that represent both gene silencing and activating marks. Furthermore, these marks are known to affect DNA methylation, and it is likely that arsenic's effect is not limited to histone modifications alone, but extends, perhaps by them, to DNA methylations as well. Future studies in our laboratory will address the genomic location of these silencing and activating marks using ChIP-on-chip technology.",
Arsenic,1349297,"Transcriptional induction of MKP-1 in response to stress is associated with histone H3 phosphorylation-acetylation Abstract: Mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1) has been shown to play a critical role in mediating the feedback control of MAP kinase cascades in a variety of cellular processes, including proliferation and stress responsiveness. Although MKP-1 expression is induced by a broad array of extracellular stimuli, the mechanisms mediating its induction remain poorly understood. Here we show that MKP-1 mRNA was potently induced by arsenite and ultraviolet light and modestly increased by heat shock and hydrogen peroxide. Interestingly, arsenite also dramatically induces phosphorylation-acetylation of histone H3 at a global level which precedes the induction of MKP-1 mRNA. The transcriptional induction of MKP-1, histone H3 modification, and elevation in MKP-1 mRNA in response to arsenite are all partially prevented by the p38 MAP kinase inhibitor SB203580, suggesting that the p38 pathway is involved in these processes. Finally, analysis of the DNA brought down by chromatin immunoprecipitation (ChIP) reveals that arsenite induces phosphorylation-acetylation of histone H3 associated with the MKP-1 gene and enhances binding of RNA polymerase II to MKP-1 chromatin. ChIP assays following exposure to other stress agents reveal various degrees of histone H3 modification at the MKP-1 chromatin. The differential contribution of p38 and ERK MAP kinases in mediating MKP-1 induction by different stress agents further illustrates the complexity and versatility of stress-induced MKP-1 expression. Our results strongly suggest that chromatin remodeling after stress contributes to the transcriptional induction of MKP-1.",
Arsenic,1326933,"Protective effect of quercetin against arsenite-induced COX-2 expression by targeting PI3K in rat liver epithelial cells Abstract: Abnormal expression of cyclooxygenase-2 (COX-2) and prostaglandin (PG)E(2) is an important mediator in inflammation and tumor promotion. Arsenite is a well-known metalloid carcinogen that is strongly associated with increased risk of liver cancer, but the underlying mechanism remains to be clarified. The present study demonstrates that COX-2 expression and PGE(2) secretion are up-regulated by arsenite in rat liver epithelial (RLE) cells. The possible inhibitory effect of quercetin, a naturally occurring dietary flavonol, on arsenite-induced COX-2 expression and PGE(2) production was investigated. Pretreatment with quercetin resulted in the reduction of arsenite-induced expression of COX-2 and production of PGE(2). The arsenite-induced phosphorylation of Akt, p70S6K, and extracellular signal-regulated protein kinases (ERKs), but not p38, was inhibited by quercetin treatment. An ex vivo kinase assay revealed that quercetin suppressed arsenite-induced phosphoinositide 3-kinase (PI3K) activity upstream of Akt in RLE cell lysates. Ex vivo pull-down assays demonstrated that quercetin directly bound with PI3K to inhibit PI3K activity. Moreover, LY294002 (a PI3K inhibitor) significantly attenuated COX-2 expression and PGE(2) production in arsenite-treated RLE cells. These results suggest that quercetin suppresses arsenite-induced COX-2 expression mainly by blocking the activation of the PI3K signaling pathway, which may contribute to its chemopreventive potential.",
Arsenic,1355019,Generation of mice with conditional null allele for GdX/Ubl4A Abstract: ,
Arsenic,1019899,"The role of soluble components in ambient fine particles-induced changes in human lungs and blood Abstract: Normal individuals developed pulmonary neutrophilic inflammation and increased blood fibrinogen following inhalation of concentrated ambient particles (CAPS). In this study, we sought to determine how soluble components in CAPS contributed to these changes. We expanded and reanalyzed data from 37 young healthy volunteers from a previous study (Ghio et al., 2000) who were exposed to either filtered air or CAPS. Postexposure bronchoalveolar lavage (BAL) as well as pre- and postexposure venous blood samples was analyzed for cellular and acute inflammatory endpoints. Nine most abundant components in the water-soluble fraction of CAPS were correlated with these endpoints using principal component analysis. We found that a sulfate/Fe/Se factor was associated with increased BAL percentage of neutrophils and a Cu/Zn/V factor with increased blood fibrinogen. The concentrations of sulfate, Fe, and Se correlated highly with PM mass (R &gt; 0.75) while the correlations between PM and Cu/Zn/V were modest (R = 0.2-0.6). These results from controlled human exposure linked specific PM components to pulmonary neutrolphil influx and blood fibrinogen increase, and indicated the soluble components of pollutant particles may differentially affect pulmonary and hematological systems in humans exposed to PM.",
Arsenic,628117,"Primary intracerebral hemorrhage mortality reduction after installation of a tap-water supply system in an arseniasis-endemic area in southwestern Taiwan Abstract: Mortality and morbidity of vascular diseases, including stroke, are known to be associated with chronic exposure to inorganic arsenic through drinking water. A tap-water supply system was implemented in the early 1960s in the blackfoot disease (BFD) endemic areas of Taiwan. The objective of this study was to examine whether mortality attributed to stroke decreased among residents living in the BFD-endemic areas after the curtailment of arsenic exposure. Further it was of interest to determine whether arsenic exposure was related to a specific type of stroke. Standardized mortality ratios (SMRs) for stroke were calculated for the BFD endemic area for the years 1971-2000. The study results show that mortality due to primary intracerebral hemorrhage (PIH) declined gradually after the improvement of drinking-water supply system by elimination of arsenic exposure through removal of artesian well water. Based on the reversibility and specificity criteria, the association between arsenic exposure and mortality due to PIH is likely to be causal.",
Arsenic,1378237,"Urogenital carcinogenesis in female CD1 mice induced by in utero arsenic exposure is enhanced by postnatal diethylstilbestrol treatment Abstract: Transplacental inorganic arsenic carcinogenicity together with postnatal exposure to diethylstilbestrol or tamoxifen was studied. Pregnant CD1 mice received 85 ppm arsenic in the drinking water from gestation day 8 to 18, and were allowed to give birth. Groups (n = 35) of female offspring were injected subcutaneously on postpartum days 1 through 5 with diethylstilbestrol (2 ug/pup/day) or tamoxifen (10 ug/pup/day) and observed for 90 weeks. Arsenic alone induced some urogenital system tumors, including mostly benign tumors of the ovary and uterus, and adrenal adenoma. Diethylstilbestrol alone induced some tumors (primarily cervical) but when given after in utero arsenic it greatly enhanced urogenital tumor incidence, multiplicity and progression. For instance, compared to the incidence of urogenital malignancies in the control (0%), arsenic alone (9%) and diethylstilbestrol alone (21%) groups, arsenic plus diethylstilbestrol induced a super-additive 48% incidence of malignant urogenital tumors. Of the urogenital tumors induced by arsenic plus diethylstilbestrol, 80% were malignant, 55% were multiple site, and 60% were associated with early death. Arsenic plus diethylstilbestrol increased ovarian, uterine, and vaginal tumors, and urinary bladder proliferative lesions, including three transitional cell carcinomas. Tamoxifen alone did not increase urogenital tumors or impact arsenic-induced neoplasia but did increase arsenic-induced uroepithelial proliferative lesions. Uterine and bladder carcinoma induced by arsenic plus diethylstilbestrol greatly overexpressed estrogen receptor-alpha (ER-alpha) and pS2, an estrogen regulated gene. In neonatal uteri, prenatal arsenic increased ER-alpha expression and enhanced estrogen-related gene expression induced by postnatal diethylstilbestrol. Thus, arsenic acts with estrogens to enhance production of female mouse urogenital cancers.",
Arsenic,1597322,"Comparative oxidation state specific analysis of arsenic species by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry and hydride generation-cryotrapping-atomic absorption spectrometry Abstract: The formation of methylarsonous acid (MAs(III)) and dimethylarsinous acid (DMAs(III)) in the course of inorganic arsenic (iAs) metabolism plays an important role in the adverse effects of chronic exposure to iAs. High-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) and hydride generation-cryotrapping-atomic absorption spectrometry (HG-CT-AAS) have been frequently used for the analysis of MAs(III) and DMAs(III) in biological samples. While HG-CT-AAS has consistently detected MAs(III) and DMAs(III), HPLC-ICP-MS analyses have provided inconsistent and contradictory results. This study compares the capacities of both methods to detect and quantify MAs(III) and DMAs(III) in an in vitro methylation system consisting of recombinant human arsenic (+3 oxidation state) methyltransferase (AS3MT), S-adenosylmethionine as a methyl donor, a non-thiol reductant tris(2-carboxyethyl)phosphine, and arsenite (iAs(III)) or MAs(III) as substrate. The results show that reversed-phase HPLC-ICP-MS can identify and quantify MAs(III) and DMAs(III) in aqueous mixtures of biologically relevant arsenical standards. However, HPLC separation of the in vitro methylation mixture resulted in significant losses of MAs(III), and particularly DMAs(III) with total arsenic recoveries below 25%. Further analyses showed that MAs(III) and DMAs(III) bind to AS3MT or interact with other components of the methylation mixture, forming complexes that do not elute from the column. Oxidation of the mixture with H2O2 which converted trivalent arsenicals to their pentavalent analogs prior to HPLC separation increased total arsenic recoveries to ~95%. In contrast, HG-CT-AAS analysis found large quantities of methylated trivalent arsenicals in mixtures incubated with either iAs(III) or MAs(III) and provided high (&gt;72%) arsenic recoveries. These data suggest that an HPLC-based analysis of biological samples can underestimate MAs(III) and DMAs(III) concentrations and that controlling for arsenic species recovery is essential to avoid artifacts.",
Arsenic,1015820,"Lack of association between essential hypertension and GSTO1 uncommon genetic variants in Italian patients Abstract: Background and Objective: Essential hypertension (EH) is a complex phenotype that is affected by multiple genetic and environmental factors. Some authors have explored the role of genetic variability of the glutathione S-transferase (GST) enzymes in EH risk with contrasting results. In particular, our previous study investigated two GSTO common polymorphisms, but we did not find a significant outcome. The aim of this research was to analyze two GSTO1 uncommon variants (E155del and E208K) in 193 EH patients and 210 healthy controls. Results: The genetic association analysis did not find significant outcome between GSTO1 uncommon variants and EH: both single-locus and haplotype investigations did not reach the statistical significance levels. Nevertheless, the correspondence analysis seems to highlight a difference between sexes: female EH patients seem to be more related to E155/del155 and E208/K208 genotypes than male patients. Conclusions: Our studies confirm the lack of association between GSTO1 variants and EH risk, also for two uncommon genetic variants with large functional effects. However, our study highlighted some hypotheses (sex-specific marker, antioxidant function, arsenic metabolism, and modulation of inflammation processes) that might help to clarify the potential role of GSTO1 in EH pathophysiology.",
Arsenic,628599,"Relative sensitivity of fish and mammalian cells to sodium arsenate and arsenite as determined by alkaline single-cell gel electrophoresis and cytokinesis-block micronucleus assay Abstract: To protect human and ecosystem health, it is necessary to develop sensitive assays and to identify responsive cells and species (and their life stages). In this study, the relative genotoxicity of two inorganic arsenicals: trivalent sodium arsenite (As(3+)) and pentavalent sodium arsenate (As(5+)), was evaluated in two cell lines of phylogenetically different origin, using alkaline single-cell gel electrophoresis (i.e., the Comet assay) and the cytokinesis-block micronucleus (MN) assay. The cell lines were the rainbow trout gonad-2 (RTG-2) and Chinese hamster ovary-K1 (CHO-K1) lines. Following optimization and validation of both assays using reference chemicals (i.e., 1-100 microM hydrogen peroxide for the Comet assay and 1-10 mM ethylmethane sulfonate for the MN assay), cells were exposed to 1-10 microM of both arsenicals to determine the relative extent of genetic damage. The unexposed controls showed similar (background) levels of damage in both cell lines and for both assays. Treatment with the arsenicals induced concentration-dependent increases in genetic damage in the two cell lines. Arsenite was more potent than arsenate in inducing DNA strand breaks in the Comet assay; at the highest concentration (10 microM) arsenite produced similar levels of DNA damage in CHO-K1 and RTG-2 cells, while 10 microM arsenate was significantly more genotoxic in RTG-2 cells. MN induction was consistently higher in RTG-2 cells than in CHO-K1 cells, with 10 microM arsenite inducing an approximate 10-fold increase in both cell lines. MN induction also was positively correlated with DNA strand breaks for both arsenicals. Overall, the study demonstrated that the fish cells are more sensitive than the mammalian cells at environmentally realistic concentrations of both arsenicals, with arsenite being more toxic.",
Arsenic,1015969,"Physical setting and natural sources of exposure to carcinogenic trace elements and radionuclides in Lahontan Valley, Nevada Abstract: In Lahontan Valley, Nevada, arsenic, cobalt, tungsten, uranium, radon, and polonium-210 are carcinogens that occur naturally in sediments and groundwater. Arsenic and cobalt are principally derived from erosion of volcanic rocks in the local mountains and tungsten and uranium are derived from erosion of granitic rocks in headwater reaches of the Carson River. Radon and (210)Po originate from radioactive decay of uranium in the sediments. Arsenic, aluminum, cobalt, iron, and manganese concentrations in household dust suggest it is derived from the local soils. Excess zinc and chromium in the dust are probably derived from the vacuum cleaner used to collect the dust, or household sources such as the furnace. Some samples have more than 5 times more cobalt in the dust than in the local soil, but whether the source of the excess cobalt is anthropogenic or natural cannot be determined with the available data. Cobalt concentrations are low in groundwater, but arsenic, uranium, radon, and (210)Po concentrations often exceed human-health standards, and sometime greatly exceed them. Exposure to radon and its decay products in drinking water can vary significantly depending on when during the day that the water is consumed. Although the data suggests there have been no long term changes in groundwater chemistry that corresponds to the Lahontan Valley leukemia cluster, the occurrence of the very unusual leukemia cluster in an area with numerous (210)Po and arsenic contaminated wells is striking, particularly in conjunction with the exceptionally high levels of urinary tungsten in Lahontan Valley residents. Additional research is needed on potential exposure pathways involving food or inhalation, and on synergistic effects of mixtures of these natural contaminants on susceptibility to development of leukemia.",
Arsenic,1378591,"Monomethylarsonous Acid Transforms Human Bladder Cells Abstract: Humans exposed to arsenic have an increased risk for the development lung, skin, and bladder cancer. Ingested arsenicals are methylated to metabolites that have been detected in urine. Trivalent, methylated arsenic metabolites are more cytotoxic and genotoxic than inorganic arsenicals. In order to better understand the mechanism of arsenic-induced carcinogenesis, it is necessary to know which arsenic metabolites are carcinogenic. To address this goal, non-tumorigenic human urothelial (UROtsa) cells were chronically exposed to 50 nM monomethylarsonous acid [MMA(III)]. Cells were monitored for anchorage-independent growth as a sign of transformation. The first phenotypic change observed in MMA(III)-treated cells (URO-MSC) was hyperproliferation, which began after 12 weeks of exposure. The 40 % reduction in doubling-time continued to be a feature of URO-MSC cells for duration of exposure (52 weeks). Anchorage-independent growth was detected after 24 weeks of exposure by growth in soft agar. To further substantiate that cellular transformation had occurred along with the induction of anchorage-independent growth, RNA was isolated from URO-MSC cells treated for 24 weeks with MMA(III) and analyzed via c-DNA microarray. Gene array data found gene expression changes to be consistent with transformation, including down-regulation of genes that regulate cell cycle (cyclin D1), cell adhesion (desmoplakin), and tumor-related genes (deleted in bladder cancer chromosome region candidate 1). Similarly, up-regulated genes were also consistent with changes occurring in transforming cells such as increases in genes that prevent apoptosis (TGF-beta-1-induced anti-apoptotic factor), facilitate metastasis (MMP-1), and were tumor-related (epithelial up-regulated in carcinoma and squamous cell carcinoma antigen). Demonstration of tumorigenicity of URO-MSC cells in SCID mice is underway. These are the first studies demonstrating MMA(III)-induced cellular transformation of any human cell line.",
Arsenic,1704107,Role of sulfate in detoxification of arsenate-induced toxicity in Zea mays L. (SRHM 445): nutrient status and antioxidants Abstract: ,
Arsenic,1344438,"Induction of the heat shock response in vivo inhibits NF-kappa B activity and protects murine liver from endotoxemia-induced injury Abstract: Liver plays an important role in the pathogenesis of sepsis by releasing various cytokines and producing acute phase proteins. Heat shock preconditioning is reported to be effective in protection of lung and liver from injury in sepsis and in endotoxemia models, but the exact mechanism is still not fully understood. We report here on the effects of the heat shock response (HSR) induced by sodium arsenite on endotoxemia-induced liver injury as well as hepatic NF-kappaB activation and proinflammatory cytokine expression. Prior induction of HSR significantly attenuated endotoxemia-induced histological changes, inhibited hepatic NF-kappaB activation and IkappaBalpha degradation and decreased mortality. Expression of mRNA coding for TNF-alpha and IL-6 in liver was significantly lower in arsenite-pretreated animals. We conclude that attenuation of endotoxin-induced hepatic NF-kappaB activation and subsequent proinflammatory cytokine production may be one of the mechanisms of the beneficial effect of the heat shock response.",1
Arsenic,2337164,"Access, monitoring and intervention challenges in the provision of safe drinking water in rural Bihar, India Abstract: This practical paper addresses the vital gap in water quality monitoring in Bihar. The study addresses an institutional weakness in the area of water quality management in rural Bihar, India. The study focuses on the role of access as a vital component in addressing water quality monitoring and interventions that has a huge impact on protecting community health in areas severely contaminated with arsenic and fluoride. The study calls for a drastic shift in the monitoring and intervention strategy to address safe water provision for rural Bihar.",
Arsenic,1345995,Exposure to arsenic in air and drinking water: Results of a study in Chile Abstract: ,
Arsenic,710952,"Impaired arsenic metabolism in children during weaning Abstract: Methylation of inorganic arsenic (iAs) via one-carbon metabolism is a susceptibility factor for a range of arsenic-related health effects, but there is no data on the importance of arsenic metabolism for effects on child development.<br /><br /> To elucidate the development of arsenic metabolism in early childhood.<br /><br /> We measured iAs, methylarsonic acid (MA) and dimethylarsinic acid (DMA), the metabolites of iAs, in spot urine samples of 2400 children at 18 months of age. The children were born to women participating in a population-based longitudinal study of arsenic effects on pregnancy outcomes and child development, carried out in Matlab, a rural area in Bangladesh with a wide range of arsenic concentrations in drinking water. Arsenic metabolism was evaluated in relation to age, sex, anthropometry, socio-economic status and arsenic exposure.<br /><br /> Arsenic concentrations in child urine (median 34 microg/L, range 2.4-940 microg/L), adjusted to average specific gravity of 1.009 g/mL, were considerably higher than that measured at 3 months of age, but lower than that in maternal urine. Child urine contained on average 12% iAs, 9.4% MA and 78% DMA, which implies a marked change in metabolite pattern since infancy. In particular, there was a marked increase in urinary %MA, which has been associated with increased risk of health effects.<br /><br /> The arsenic metabolite pattern in urine of children at 18 months of age in rural Bangladesh indicates a marked decrease in arsenic methylation efficiency during weaning.",
Arsenic,1347335,"Arsenic, Copper, and Zinc Leaching through Preferential Flow in Mining-Impacted Soils Abstract: ",
Arsenic,627987,"Chronic inorganic arsenic exposure induces hepatic global and individual gene hypomethylation: Implications for arsenic hepatocarcinogenesis Abstract: Inorganic arsenic is a human carcinogen that can target the liver, but its carcinogenic mechanisms are still unknown. Global DNA hypomethylation occurs during arsenic-induced malignant transformation in rodent liver cells. DNA hypomethylation can increase gene expression, particularly when occurring in the promoter region CpG sites, and may be a non-genotoxic mechanism of carcinogenesis. Thus, in the present study liver samples of male mice exposed to 0 (control) or 45 p.p.m. arsenic (as NaAsO(2)) in the drinking water for 48 weeks were analyzed for gene expression and DNA methylation. Chronic arsenic exposure caused hepatic steatosis, a lesion also linked to consumption of methyl-deficient diets. Microarray analysis of liver samples showed arsenic induced aberrant gene expression including steroid-related genes, cytokines, apoptosis-related genes and cell cycle-related genes. In particular, the expression of the estrogen receptor-alpha (ER-alpha), and cyclin D1 genes were markedly increased. RT-PCR and immunohistochemistry confirmed arsenic-induced increases in hepatic ER-alpha and cyclin D1 transcription and translation products, respectively. Arsenic induced hepatic global DNA hypomethylation, as evidenced by 5-methylcytosine content of DNA and by the methyl acceptance assay. Arsenic also markedly reduced the methylation within the ER-alpha gene promoter region, as assessed by methylation-specific PCR, and this reduction was statistically significant in 8 of 13 CpG sites within the promoter region. Overall, in controls 28.3% of the ER-alpha promoter region CpG sites were methylated, but only 2.9% were methylated after chronic arsenic exposure. Thus, long-term exposure of mice to arsenic in the drinking water can induce aberrant gene expression, global DNA hypomethylation, and the hypomethylation of the ER-alpha gene promoter, all of which could potentially contribute to arsenic hepatocarcinogenesis.",
Arsenic,1347656,Arsenic-induced NF kappa beta transactivation through Erks- and JNKs-dependent pathways in mouse epidermal JB6 cells Abstract: ,
Arsenic,1032261,"Investigations of the gallbladder pathology associated with dietary exposure to disodium arsenate heptahydrate in juvenile rainbow trout (Oncorhynchus mykiss) Abstract: Juvenile rainbow trout were fed semi-purified diets with (58 ?g As/g diet) or without arsenic, added as disodium arsenate heptahydrate (DSA), under standard laboratory conditions for up to 12 weeks, to determine the time-course of development of gallbladder pathology in response to dietary DSA exposure, to correlate this pathology with levels of total arsenic and specific arsenic metabolites in the hepatobiliary system and thereby to attempt to gain some insight regarding the mechanism(s) by which the pathological changes develop. Gallbladder lesions associated with this level of dietary arsenic exposure to juvenile rainbow trout include acute inflammation with oedema of the submucosal tissues and sloughing of the epithelium within the first day of exposure, developing to chronic inflammation with fibrosis of the gallbladder wall. These changes may result from the toxic influence of arsenite absorbed into the epithelial cells. The arsenic content of washed gallbladder tissue is a sensitive indicator of recent dietary DSA exposure, while the chronic inflammatory lesion with extensive fibrosis of the gallbladder wall may provide a longer-term indicator of exposure to toxic levels of DSA in the diet of rainbow trout.",
Arsenic,62129,"Arsenic exposure and mortality: A case-referent study from a Swedish copper smelter Abstract: An increased mortality from lung cancer, cardiovascular disease, haematolymphatic malignancy and cirrhosis of the liver has been reported among smelter workers and others exposed to arsenic. This study uses the case-referent (case-control) technique and is concerned with workers in a copper smelter in a complex work environment, characterised by the presence of trivalent arsenic in combination with sulphur dioxide and copper, and also with other agents. Lung cancer mortality was found to be increased about five-fold and cardiovascular disease about two-fold, showing a dose-response relationship to arsenic exposure. Mortality from malignant blood disease (leukaemia and myeloma) and cirrhosis of the liver was also slightly increased. This mortality pattern among the smelter workers is consistent with earlier reports. An increased mortality from cardiovascular disease in this type of industry is of particular interest as it has been reported only once before.",
Arsenic,130566,"Recent advances in arsenic carcinogenesis: Modes of action, animal model systems, and methylated arsenic metabolites Abstract: Recent advances in our knowledge of arsenic carcinogenesis include the development of rat or mouse models for all human organs in which inorganic arsenic is known to cause cancer-skin, lung, urinary bladder, liver, and kidney. Tumors can be produced from either promotion of carcinogenesis protocols (mouse skin and lungs, rat bladder, kidney, liver, and thyroid) or from complete carcinogenesis protocols (rat bladder and mouse lung). Experiments with p53(+/-) and K6/ODC transgenic mice administered dimethylarsinic acid or arsenite have shown some degree of carcinogenic, cocarcinogenic, or promotional activity in skin or bladder. At present, with the possible exception of skin, the arsenic carcinogenesis models in wild-type animals are more highly developed than in transgenic mice. Recent advances in arsenic metabolism have suggested that methylation of inorganic arsenic may be a toxification, rather than a detoxification, pathway and that trivalent methylated arsenic metabolites, particularly monomethylarsonous acid and dimethylarsinous acid, have a great deal of biological activity. Accumulating evidence indicates that these trivalent, methylated, and relatively less ionizable arsenic metabolites may be unusually capable of interacting with cellular targets such as proteins and even DNA. In risk assessment of environmental arsenic, it is important to know and to utilize both the mode of carcinogenic action and the shape of the dose-response curve at low environmental arsenic concentrations. Although much progress has been recently made in the area of arsenic's possible mode(s) of carcinogenic action, a scientific concensus has not yet been reached. In this review, nine different possible modes of action of arsenic carcinogenesis are presented and discussed-induced chromosomal abnormalities, oxidative stress, altered DNA repair, altered DNA methylation patterns, altered growth factors, enhanced cell proliferation, promotion/progression, gene amplification, and suppression of p53.",
Arsenic,1021526,"A risk-benefit analysis approach to seafood intake to determine optimal consumption Abstract: Seafood provides n-3 long-chain PUFA (n-3 LC-PUFA), vitamins and minerals, which are essential to maintain good health. Moreover, seafood is a source of contaminants such as methylmercury, arsenic and persistent organic pollutants that may affect health. The aim of the present study was to determine in what quantities seafood consumption would provide nutritional benefits, while minimising the risks linked to food contaminants. Seafood was grouped into clusters using a hierarchical cluster analysis. Those nutrients and contaminants were selected for which it is known that seafood is a major source. The risk-benefit analysis consisted in using an optimisation model with constraints to calculate optimum seafood cluster consumption levels. The goal was to optimise nutrient intakes as well as to limit contaminant exposure with the condition being to attain recommended nutritional intakes without exceeding tolerable upper intakes for contaminants and nutrients, while taking into account background intakes. An optimum consumption level was calculated for adults that minimises inorganic arsenic exposure and increases vitamin D intake in the general population. This consumption level guarantees that the consumer reaches the recommended intake for n-3 LC-PUFA, Se and I, while remaining below the tolerable upper intakes for methylmercury, Cd, dioxins, polychlorobiphenyls, Zn, Ca and Cu. This consumption level, which is approximately 200 g/ week of certain fatty fish species and approximately 50 g/week of lean fish, molluscs and crustaceans, has to be considered in order to determine food consumption recommendations in a public health perspective.",
Arsenic,1016220,"Comparison of atomic absorption and fluorescence spectroscopic methods for the routine determination of urinary arsenic Abstract: <strong>OBJECTIVE: </strong>Interpretation of urinary arsenic measurements is sometimes difficult because of the absorption of seafood that contains trimethylated arsenic forms (arsenobetaine and arsenocholine). The objective of this study was to develop a rapid and robust technique for the measurement of the sum of inorganic arsenic metabolites.<br /><br /><strong>METHODS: </strong>Measurement of arsenic was performed in urine after hydride generation in acid medium. Using atomic fluorescence spectrometry (AFS) as the detection system, we developed a rapid (one determination in less than 2 min) technique using 50 microl urine without pre-treatment. Standardisation was done externally with a mixed standard solution containing inorganic trivalent arsenic (As(i) (III)), inorganic pentavalent arsenic (As(i) (V)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) (15/15/12.5/57.5).<br /><br /><strong>RESULTS: </strong>Samples distributed in the frame of an international comparison programme were used to assess accuracy of the AFS procedure, which gives a linear response up to 50 microg/l and proves more precise [coefficient of variation (CV)&lt; 4% at 5 microg/l] and sensitive than the atomic absorption spectroscopy (AAS) technique using a quartz cell. An additional adaptation that allows the detection of non-directly reducible arsenic forms has also been validated for samples with high arsenic concentrations.<br /><br /><strong>CONCLUSIONS: </strong>The present study demonstrates the superiority of AFS over atomic absorption spectrometry (AAS) in arsenic determination and the interest of online mineralisation prior AFS detection for the determination of arsenic concentration in urine.",
Arsenic,2279262,"Food crop accumulation and bioavailability assessment for antimony (Sb) compared with arsenic (As) in contaminated soils Abstract: Field samples and a 9-week glasshouse growth trial were used to investigate the accumulation of mining derived arsenic (As) and antimony (Sb) in vegetable crops growing on the Macleay River Floodplain in Northern New South Wales, Australia. The soils were also extracted using EDTA to assess the potential for this extractant to be used as a predictor of As and Sb uptake in vegetables, and a simplified bioaccessibility extraction test (SBET) to understand potential for uptake in the human gut with soil ingestion. Metalloids were not detected in any field vegetables sampled. Antimony was not detected in the growth trial vegetable crops over the 9-week greenhouse trial. Arsenic accumulation in edible vegetable parts was &lt;10 % total soil-borne As with concentrations less than the current Australian maximum residue concentration for cereals. The results indicate that risk of exposure through short-term vegetable crops is low. The data also demonstrate that uptake pathways for Sb and As in the vegetables were different with uptake strongly impacted by soil properties. A fraction of soil-borne metalloid was soluble in the different soils resulting in Sb soil solution concentration (10.75?±?0.52 ?g L(-1)) that could present concern for contamination of water resources. EDTA proved a poor predictor of As and Sb phytoavailability. Oral bioaccessibility, as measured by SBET, was &lt;7 % for total As and &lt;3 % total Sb which is important to consider when estimating the real risk from soil borne As and Sb in the floodplain environment.",
Arsenic,2149172,"Arsenic disulfide-triggered apoptosis and erythroid differentiation in myelodysplastic syndrome and acute myeloid leukemia cell lines Abstract: <strong>OBJECTIVES: </strong>Effects of arsenic disulfide (As2S2) were investigated by focusing on growth inhibition, apoptosis induction, and erythroid differentiation in MDS-L, F-36p and HL-60 cells, derived from myelodysplastic syndrome (MDS), MDS/acute myeloid leukemia (AML), and de novo AML, respectively.<br /><br /><strong>METHODS: </strong>Cell viability was determined by MTT assay. Apoptosis induction was analyzed using Annexin V/propidium iodide staining. Erythroid differentiation was assessed by the expression level of CD235a, a marker for detection of the erythroid cell lineage. The activation of p38 MAPK and the expression profile of apoptosis-related proteins Bcl-2 and Bid were analyzed using western blot.<br /><br /><strong>RESULTS: </strong>As2S2 inhibited cell growth of these cell lines. Of note, the IC50 value of As2S2 in MDS-L cells was comparable to that in F-36p cells, and was half of that in HL-60 cells. A dose-dependent decrease in cell viability and concomitant increase in the percentage of apoptotic cells were observed in F-36p cells treated with 8 and 16 µM As2S2 for 72 hours. However, similar phenomena were only observed in HL-60 cells when treated with as high as 16 µM As2S2. Furthermore, As2S2 exerted more potent erythroid differentiation-inducing activity on F-36p cells than HL-60 cells. Interestingly, negative correlation between p38 MAPK signaling pathway and As2S2-induced erythroid differentiation was observed in HL-60 cells. Treatment with relatively high concentration of As2S2 resulted in the downregulation of Bcl-2 and Bid proteins in HL-60 cells.<br /><br /><strong>DISCUSSION: </strong>These results suggest that compared to AML cell line, MDS and MDS/AML cell lines are more sensitive to not only the erythroid differentiation-inducing activity of As2S2, but also its cytotoxicity associated with apoptosis induction. These findings further provide novel insight into As2S2 action toward its use for clinical application in patients with hematological disorders.",
Arsenic,2347745,"Comparative study of the genotoxic response of freshwater mussels Unio tumidus and Unio pictorum to environmental stress Abstract: Genotoxic response of freshwater mussels U. tumidus and U. pictorum to environmental stress was studied using comet assay on hemocytes and gill cells. The mussels were acclimated to controlled laboratory conditions for 10 days, and then exposed at 4 sites in the Sava and Danube rivers in the area of the city of Belgrade. Samples of each species were taken after 7, 14, and 30 days of exposure. The mussels sampled immediately after acclimation served as controls. Genotoxic response in both species was induced earlier at sites receiving untreated wastewaters from the city's main collectors (7 days), than at the site receiving only domestic wastewaters from small settlements located upstream from the city (30 days). There was a correlation between the comet tail intensity values in tissues of exposed mussels and the concentrations of zinc, copper, iron, and arsenic at the exposure sites. The genotoxic responses in both tissues of U. pictorum and in hemocytes of U. tumidus were similar, while U. tumidus gill cells failed to exhibit significant genotoxic response at two sites. These findings, together with higher mortality of U. tumidus at the most polluted sites, promote U. pictorum as a model for genotoxicity monitoring in freshwater environments.",
Arsenic,1028971,"Fungal volatilization of trivalent and pentavalent arsenic under laboratory conditions Abstract: Production of volatile derivatives of arsenic was studied using pure cultures of different fungal strains under laboratory conditions. Arsenic was used in its trivalent and pentavalent forms to evaluate the effect of arsenic valency on its biovolatilization. The average amount of volatilized arsenic for all fungal strains ranged from 0.026 mg to 0.257 mg and 0.024 mg to 0.191 mg of trivalent and pentavalent arsenic, respectively. These results show that approximately 23% of arsenic was volatilized from all culture media originally enriched with approximately 4 and 17 mg L(-1) of arsenic in trivalent form. The average amount of biovolatilized arsenic from culture media originally enriched with 4 and 17 mg L(-1) of arsenic in pentavalent form was 24% and 16%, respectively. The order of ability of arsenic biovolatilization is Neosartorya fischeri &gt; Aspergillus clavatus &gt; Aspergillus niger. Toxicity and fungal resistance to trivalent and pentavalent arsenic were also evaluated based on radial growth and biomass weight.",
Arsenic,2278555,"A role for glutamate-333 of Saccharomyces cerevisiae cystathionine ?-lyase as a determinant of specificity Abstract: Cystathionine ?-lyase (CGL) catalyzes the hydrolysis of L-cystathionine (L-Cth), producing L-cysteine (L-Cys), ?-ketobutyrate and ammonia, in the second step of the reverse transsulfuration pathway, which converts Lhomocysteine (L-Hcys) to L-Cys. Site-directed variants substituting residues E48 and E333 with alanine, aspartate and glutamine were characterized to probe the roles of these acidic residues, conserved in fungal and mammalian CGL sequences, in the active-site of CGL from Saccharomyces cerevisiae (yCGL). The pH optimum of variants containing the alanine or glutamine substitutions of E333 is increased by 0.4–1.2 pH units, likely due to repositioning of the cofactor and modification of the pKa of the pyridinium nitrogen. The pH profile of yCGL-E48A/E333A resembles that of Escherichia coli cystathionine ?-lyase. The effect of substituting E48, E333 or both residues is the 1.3–3, 26–58 and 124–568-fold reduction, respectively, of the catalytic efficiency of L-Cth hydrolysis. The Km L-Cth of E333 substitution variants is increased ~17-fold, while Km L-OAS is within 2.5-fold of the wild-type enzyme, indicating that residue E333 interacts with the distal amine moiety of L-Cth, which is not present in the alternative substrate O-acetyl-L-serine. The catalytic efficiency of yCGL for ?,?-elimination of O-succinyl-L-homoserine (kcat/Km L-OSHS = 7 ± 2), which possesses a distal carboxylate, but lacks an amino group, is 300-fold lower than that of the physiological L-Cth substrate (kcat/Km L-Cth = 2100 ± 100) and 260-fold higher than that of L-Hcys (kcat/Km L-Hcys = 0.027 ± 0.005), which lacks both distal polar moieties. The results of this study suggest that the glutamate residue at position 333 is a determinant of specificity.",
Arsenic,1026054,"Risk assessment of trace elements in the stomach contents of Indo-Pacific Humpback Dolphins and Finless Porpoises in Hong Kong waters Abstract: The potential health risks due to inorganic substances, mainly metals, was evaluated for the two resident marine mammals in Hong Kong, the Indo-Pacific Humpback Dolphin (Sousa chinensis) and the Finless Porpoise (Neophocaena phocaenoides). The stomachs from the carcasses of twelve stranded dolphins and fifteen stranded porpoises were collected and the contents examined. Concentrations of thirteen trace elements (Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mn, Ni, Se, V and Zn) were determined by inductively coupled plasma mass spectrometer (ICP-MS). An assessment of risks of adverse effects was undertaken using two toxicity guideline values, namely the Reference Dose (RfD), commonly used in human health risk assessment, and the Toxicity Reference Value (TRV), based on terrestrial mammal data. The levels of trace metals in stomach contents of dolphins and porpoises were found to be similar. Risk quotients (RQ) calculated for the trace elements showed that risks to the dolphins and porpoises were generally low and within safe limits using the values based on the TRV, which are less conservative than those based on the RfD values. Using the RfD-based values the risks associated with arsenic, cadmium, chromium, copper, nickel and mercury were comparatively higher. The highest RQ was associated with arsenic, however, most of the arsenic in marine organisms should be in the non-toxic organic form, and thus the calculated risk is likely to be overestimated.",
Arsenic,2088488,"A vibrational spectroscopic study of the silicate mineral ardennite-(As) Abstract: We have used a combination of scanning electron microscopy with EDX and vibrational spectroscopy to study the mineral ardennite-(As). The mineral ardennite-(As) of accepted formula Mn4(2+)(Al,Mg)6(Si3O10)(SiO4)2(AsO4,VO4)(OH)6 is a silicate mineral which may contain arsenate and/or vanadates anions. Because of the oxyanions present, the mineral lends itself to analysis by Raman and infrared spectroscopy. Qualitative chemical analysis shows a homogeneous phase, composed by Si, Mn, Al and As. Ca and V were also observed in partial substitution for Mn and As. Raman bands at 1197, 1225, 1287 and 1394cm(-1) are assigned to SiO stretching vibrations. The strong Raman bands at 779 and 877cm(-1) are assigned to the AsO4(3-) antisymmetric and symmetric stretching vibrations. The Raman band at 352cm(-1) is assigned to the ?2 symmetric bending vibration. The series of Raman bands between 414 and 471cm(-1)are assigned to the ?4 out of plane bending modes of the AsO4(3-) units. Intense Raman bands observed at 301 and 314cm(-1) are attributed to the MnO stretching and bending vibrations. Raman bands at 3041, 3149, 3211 and 3298cm(-1) are attributed to the stretching vibrations of OH units. There is vibrational spectroscopic evidence for the presence of water adsorbed on the ardennite-(As) surfaces.",
Arsenic,1018604,"Assessment of exposure to inorganic arsenic, a human carcinogen, due to the consumption of seafood Abstract: To assess whether regular consumption of seafood, particularly fish and shellfish, by humans may lead to an overexposure to inorganic arsenic, a well-established human carcinogen, the urinary excretion of the relevant As metabolites (Asi, inorganic form; MMA, monomethylarsonic acid; DMA, dimethylarsinic acid) was compared in groups of subjects with different seafood consumption habits and in volunteers after ingestion of a known amount of seafood arsenicals. Studies of Italian cohorts, involving five groups of +/-30 subjects with different seafood consumption habits, and balance studies in Belgian volunteers failed to show a biologically significant absorption of inorganic arsenic either present as such in the food or formed from organoarsenicals during cooking or digestion. The results suggest that the digestion of some seafood, especially mussels, may increase the urinary excretion of the dimethylated arsenic metabolite. Therefore, the biological monitoring of exposure to inorganic arsenic in an industrial context should mainly rely upon specific measurement of the unmetabolized form when recent ingestion of seafood cannot be excluded.",
Arsenic,1337670,"Silibinin ameliorates arsenic induced nephrotoxicity by abrogation of oxidative stress, inflammation and apoptosis in rats Abstract: Arsenic (As) is an environmental and industrial pollutant that affects various organs in human and experimental animals. Silibinin is a naturally occurring plant bioflavonoid found in the milk thistle of Silybum marianum, which has been reported to have a wide range of pharmacological properties. A body of evidence has accumulated implicating the free radical generation with subsequent oxidative stress in the biochemical and molecular mechanisms of As toxicity. Since kidney is the critical target organ of chronic As toxicity, we carried out this study to investigate the effects of silibinin on As-induced toxicity in the kidney of rats. In experimental rats, oral administration of sodium arsenite [NaAsO(2), 5 mg/(kg day)] for 4 weeks significantly induced renal damage which was evident from the increased levels of serum urea, uric acid, creatinine with a significant (p &lt; 0.05) decrease in creatinine clearance. As also significantly decreased the levels of urea, uric acid and creatinine in urine. A markedly increased levels of lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl contents with significant (p &lt; 0.05) decrease in non-enzymatic antioxidants (total sulfhydryl groups, reduced glutathione, vitamin C and vitamin E) and enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glutathione S-transferase), Glutathione metabolizing enzymes (glutathione reductase and glutathione-6-phosphate dehydrogenase) and membrane bound ATPases were also observed in As treated rats. Co-administration of silibinin (75 mg/kg day) along with As resulted in a reversal of As-induced biochemical changes in kidney accompanied by a significant decrease in lipid peroxidation and an increase in the level of renal antioxidant defense system. The histopathological and immunohistochemical studies in the kidney of rats also shows that silibinin (75 mg/kg day) markedly reduced the toxicity of As and preserved the normal histological architecture of the renal tissue, inhibited the caspase-3 mediated tubular cell apoptosis and decreased the NADPH oxidase, iNOS and NF-?B over expression by As and upregulated the Nrf2 expression in the renal tissue. The present study suggests that the nephroprotective potential of silibinin in As toxicity might be due to its antioxidant and metal chelating properties, which could be useful for achieving optimum effects in As-induced renal damage.",
Arsenic,1337515,"Oxidative DNA damage of peripheral blood polymorphonuclear leukocytes, selectively induced by chronic arsenic exposure, is associated with extent of arsenic-related skin lesions Abstract: There is increasing evidence that oxidative stress is an important risk factor for arsenic-related diseases. Peripheral blood leukocytes constitute an important defense against microorganisms or pathogens, while the research on the impact of chronic arsenic exposure on peripheral blood leukocytes is much more limited, especially at low level arsenic exposure. The purpose of the present study was to explore whether chronic arsenic exposure affects oxidative stress of peripheral blood leukocytes and possible linkages between oxidative stress and arsenic-induced skin lesions. 75 male inhabitants recruited from an As-endemic region of China were investigated in the present study. The classification of arsenicosis was based on the degree of skin lesions. Arsenic levels were measured in drinking water and urine by Atomic Fluorescence Spectroscopy. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was tested by Enzyme-Linked Immunosorbent Assay. 8-OHdG of peripheral blood leukocytes was evaluated using immunocytochemical staining. 8-OHdG-positive reactions were only present in polymorphonuclear leukocytes (PMNs), but not in monocytes (MNs). The 8-OHdG staining of PMN cytoplasm was observed in all investigated populations, while the 8-OHdG staining of PMN nuclei was frequently found along with the elevated amounts of cell debris in individuals with skin lesion. Urinary arsenic levels were increased in the severe skin lesion group compared with the normal group. No relationship was observed between drinking water arsenic or urine 8-OHdG and the degree of skin lesions. These findings indicated that the target and persistent oxidative stress in peripheral blood PMNs may be employed as a sensitive biomarker directly to assess adverse health effects caused by chronic exposure to lower levels of arsenic.",
Arsenic,1240272,"Heavy metal analysis around Murgul (Artvin) copper mining area of Turkey using moss and soil Abstract: This research investigates heavy metal pollution around one of the most important mining areas in Turkey, the Murgul mining, by means of analyzing moss and soil samples collected in the neighborhood of the copper mining at different distances. Energy dispersive X-ray fluorescence (EDXRF) spectrometry (Epsilon 5, PANalytical, Almelo, The Netherlands) is utilized in the experiments. The results have indicated that the both moss and soil samples contain Aluminum, Vanadium, Chromium, Manganese, Iron, Nickel, Copper, Zinc, Arsenic and Lead. The comparison of the heavy metal concentrations with the typical measurements in the world and with the limit values for the human health has revealed the critical heavy metal pollution levels in the region, where one of Turkey's first environmental spills was also observed. The possible consequences of these results are briefly discussed from the point of potential hazards to ecology and human health.",
Arsenic,1329992,"Transcriptional activation and posttranscriptional modification of Cyp1a1 by arsenite, cadmium, and chromium Abstract: Heavy metals alter the carcinogenicity of AhR ligands by modulating the induction of the Cyp1a1 enzyme, but the mechanism(s) remain unresolved. In this study, the effect of the heavy metals, As(3+), Cd(2+), and Cr(6+), on the transcriptional and posttranscriptional regulation of the Cyp1a1 gene was investigated in Hepa 1c1c7 cells. A time-dependent study showed that all metals significantly induced the basal Cyp1a1 mRNA, but only As(3+) and Cd(2+) further potentiated the inducible Cyp1a1 mRNA level. Alternately, Cr(6+) inhibited the TCDD-mediated induction of Cyp1a1 mRNA. As(3+) potentiated the induction of Cyp1a1 mRNA by TCDD only at 3h and 6h after treatment. Cd(2+) on the other hand further potentiated the induction up to 24h after treatment. The metal-mediated induction of Cyp1a1 mRNA was further potentiated by the protein synthesis inhibitor, cycloheximide and the 26S proteasome inhibitor, MG-132, but completely inhibited by the RNA transcription inhibitor, actinomycin-D, implying a transcriptional regulation of the Cyp1a1 gene by the heavy metals. Not surprisingly, Cd(2+) and Cr(6+) activated the DNA-binding capacity of the AhR for the xenobiotic responsive element, as measured by the electrophoretic-mobility shift assay while all three metals induced AhR-dependent luciferase reporter gene expression in transiently transfected Hepa 1c1c7 cells. On the other hand, only As(3+) increased the Cyp1a1 mRNA half-life while Cd(2+) and Cr(6+) increased the Cyp1a1 protein half-life, suggesting the involvement of posttranslational modifications. A significant decrease in TCDD-mediated induction of Cyp1a1 activity was associated with an increase in HO-1 mRNA levels and a concomitant decrease in cellular heme content after all metal treatments. We clearly demonstrated that As(3+), Cd(2+), and Cr(6+) increase Cyp1a1 mRNA levels at the transcriptional and posttranscriptional levels while decreasing Cyp1a1 activity at the posttranslational level.",
Arsenic,1519202,"Identification of deubiquitinating enzymes involved in methylmercury toxicity in Saccharomyces cerevisiae Abstract: Deubiquitinating enzymes that influence the methylmercury susceptibility of yeast cells were investigated. Deficiency of Ubp2, Ubp4, Ubp 6, or Ubp14 conferred methylmercury resistance on cells, while deficiency of Ubp7, Ubp13, or Ubp15 conferred high methylmercury susceptibility. Of these enzymes, deficiency of Ubp4 and Ubp6 was associated with particularly high methylmercury resistance. Yeast cells treated with a proteasome inhibitor showed methylmercury resistance due to Ubp4 deficiency, but not due to Ubp6 deficiency. Thus, the enhanced methylmercury toxicity associated with Ubp6 expression requires proteasomal activity, suggesting that Ubp4 and Ubp6 contribute to enhanced methylmercury toxicity through different mechanisms.",
Arsenic,628399,"Acute myocardial infarction mortality in comparison with lung and bladder cancer mortality in arsenic-exposed region II of Chile from 1950 to 2000 Abstract: Arsenic in drinking water is known to be a cause of lung, bladder, and skin cancer, and some studies report cardiovascular disease effects. The authors investigated mortality from 1950 to 2000 in the arsenic-exposed region II of Chile (population: 477,000 in 2000) in comparison with the unexposed region V. Increased risks were found for acute myocardial infarction (AMI), with mortality rate ratios of 1.48 for men (95% confidence interval (CI): 1.37, 1.59; p < 0.001) and 1.26 for women (95% CI: 1.14, 1.40; p < 0.001) during the high-exposure period in region II from 1958 to 1970. The highest rate ratios were for young adult men aged 30-49 years who were born during the high-exposure period with probable exposure in utero and in early childhood (rate ratio = 3.23, 95% CI: 2.79, 3.75; p < 0.001). Compared with lung and bladder cancer, AMI mortality was the predominant cause of excess deaths during and immediately after the high-exposure period. Ten years after reduction of exposures, AMI mortality had decreased, and longer latency excess deaths from lung and bladder cancer predominated. With these three causes of death combined, increased mortality peaked in 1991-1995, with estimated excess deaths related to arsenic exposure constituting 10.9% of all deaths among men and 4.0% among women.",
Arsenic,2345640,"Renin-angiotensin-aldosterone system related gene polymorphisms and urinary total arsenic is related to chronic kidney disease Abstract: A recent study demonstrated that an increased risk of chronic kidney disease (CKD) was associated with high urinary total arsenic levels. However, whether genomic instability is related to CKD remains unclear. An association between CKD and genetic polymorphisms of regulation enzymes of the renin-angiotensin-aldosterone system (RAAS), such as angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II type I receptor (AT1R), and aldosterone synthase (CYP11B2) has not been shown. The aim of the present study was to investigate the relationship between arsenic, genetic polymorphisms of RAAS enzymes and CKD. A total of 233 patients and 449 age- and gender-matched controls were recruited from the Taipei Medical University Hospital, Taipei Municipal Wan Fang Hospital and the Shin Kong Wu Ho-Su Memorial Hospital. Concentrations of urinary arsenic were determined by a high-performance liquid chromatography-linked hydride generator, and atomic absorption spectrometry. Polymorphisms of ACE(I/D), AGT(A[-20]C), (T174M), (M235T), AT1R(A1166C) and CYP11B2(C[-344]T) were examined by polymerase chain reaction and restriction fragment length polymorphism. Subjects carrying the CYP11B2 TT genotype had a higher odds ratio (OR), 1.39 (0.96-2.01), of CKD; while those with the AGT(A[-20]C) CC genotype had an inverse OR of CKD (0.20 (0.05-0.81)), and a high-risk genotype was defined as A/A+A/C for AGT(A[-20C]) and T/T for CYP11B2(C[-344]T). The trend test showed a higher OR for CKD in patients who had either high urinary total arsenic levels or carried the high-risk genotype, or both, compared to patients with low urinary total arsenic levels, who carried the low-risk genotype, and could also be affected by the hypertension or diabetes status.",
Arsenic,1344637,"Occurrence of cancer in arsenic contaminated area, Ronpibool District, Nakorn Srithmmarat Province, Thailand Abstract: Arsenic contamination in Ronpibool district, Nakorn Srithammarat, the southern province of Thailand, has been discovered more than 10 years ago. However, the evidence of human cancer in this population has not been thoroughly studied. This study aimed to assess the prevalence of cancer from two main methods: (a) analysis of secondary data from 5-years (1994-1998) cancer registry of the Prince of Songkhla University, (b) investigation of causes of death using verbal autopsy and hospital records in 1998. When comparing 5-year prevalence of cancer from the cancer registry, Ronpibool district (2.2 per 1000 population) ranked fifth among the 23 districts. When comparing cancer sites among the first 5 high-prevalence districts, Hausai (3.19/1000), Lansaka (2.29/1000), Phomkiri (2.23/1000), Kanom (2.23/1000) and Ronpibool (2.20/1000), lung cancer was the highest in Hausai, Lansaka and Phomkiri, while cancer of the oral cavity (includes cancer of tongue, palate, mouth, saliva gland, parotid gland and tonsil) was found the highest in Kanom. For Ronpibool district lymphoma (includes Hodgkin's, follicular node, diffuse non-Hodgkin's, T-cell and other lymphoma) and breast cancer had the highest proportion (13.5) followed by lung cancer (10.2) districts, however among the top five districts, Ronpibool had the highest proportion of skin cancer (3.4 in females in four of these five Districts). The study to verify causes of death in Nakorn Srithammarat province in 1998 found a different pattern. The highest death rate from cancer was in Kanom District (120.5 per 100,000), followed by Chalermprakiet (69.7), Hausai (56.7) and Lansaka (57.4). Ronpibool district ranked 12 with a cancer death rate of 31.1 per 100,000. In every District, most cancer patients died at the age of 45 and over, and males had a higher number of deaths than females in these age groups. Details of the evidences will be discussed.",
Arsenic,1508636,"Systems biology approaches to evaluate arsenic toxicity and carcinogenicity: An overview Abstract: Long term exposure to arsenic, either through groundwater, food stuff or occupational sources, results in a plethora of dermatological and non-dermatological health effects including multi-organ cancer and early mortality. Several epidemiological studies, across the globe have reported arsenic-induced health effects and cancerous outcomes; but the prevalence of such diseases varies depending on environmental factors (geographical location, exposure level), and genetic makeup (and variants thereof); which is further modulated by several other factors like ethnicity, age-sex, smoking status, diet, etc. It is also interesting to note that, chronic arsenic exposure to a similar extent, even among the same family members, result in wide inter-individual variations. To understand the adverse effect of this toxic metabolite on biological system (cellular targets), and to unravel the underlying molecular basis (at the level of transcript, proteome, or metabolite), a holistic, systems biology approach was taken. Due to the paradoxical nature and unavailability of any suitable animal model system; the literature review is primarily based on cell line and population based studies. Thus, here we present a comprehensive review on the systems biology approaches to explore the underlying mechanism of arsenic-induced carcinogenicity, along with our own observations and an overview of mitigation strategies and their effectiveness till date.",
Arsenic,2088418,"Simple and efficient synthesis of iron oxide-coated silica gel adsorbents for arsenic removal: Adsorption isotherms and kinetic study Abstract: Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption of the anionic form of arsenic oxyacids, arsenite () and arsenate (), onto hematite coated silica gel was fitted against non-linear 3-parameter-model Sips isotherm and 2-parameter-model Langmuir and Freundlich isotherm. Adsorption kinetics of arsenic could be well described by pseudo-second-order kinetic model and value of adsorption energy derived from non-linear Dubinin-Radushkevich isotherm suggests chemical adsorption. Although arsenic adsorption process was not affected by the presence of sulfate, chloride, and nitrate anions, as expected, bicarbonate and silicate gave moderate negative effects while the presence of phosphate anions significantly inhibited adsorption process of both arsenite and arsenate. When the actual efficiency to remove arsenic was tested against 1 L of artificial arsenic-contaminated groundwater (0.6 mg/L) in the presence competing anions, the reasonable amount (20 g) of hematite coated silica gel could reduce arsenic concentration to below the WHO permissible safety limit of drinking water of without adjusting pH and temperature, which would be highly advantageous for practical field application.",
Arsenic,2279207,"Assessment of children's exposure to arsenic from CCA-wood staircases at apartment complexes in Florida Abstract: Arsenic exposure from wood treated with chromated copper arsenate (CCA) remains a concern due to its presence around homes. This study evaluated children's exposure to As from CCA-treated staircases through determination of bioaccessible soil As and measurements of dislodgeable As on hand railings, steps and surfaces of household objects impacted by CCA-wood leachate. Total As concentrations in 84 soil samples from 4 apartment complexes were elevated at 1.2-66.6mg/kg with bioaccessible As at 17-84%. Deterministic risk equations were used to estimate daily doses of As in children with estimates ranging from 0.41-54.9?g/day from ingestion of dislodgeable As. Lifetime average daily doses from ingestion of dislodgeable As and soil ranged from 8.1×10(-6) to 3.0×10(-5)mg/kg/day, with estimated cancer risks being 1.2-4.5×10(-5). Collectively, these results highlight potential health risks in children who have near-daily exposure to As from CCA-wood and are consistent with estimates generated by USEPA's SHEDS-Wood probabilistic exposure model.",
Arsenic,1015937,"Case-control study of male cancer patients exposed to arsenic-contaminated drinking water and tobacco smoke with relation to non-exposed cancer patients Abstract: The investigated data indicated that inorganic arsenic in drinking water is associated with increased mortality from different types of cancers. In the present study, biological samples (blood and scalp hair) of male subjects having lung and bladder cancers and non-cancerous subjects belonging to arsenic (As)-exposed area of southern parts of Pakistan were analysed for As contents. The As levels in drinking water of understudy area showed that sections of understudy population are exposed to arsenic concentrations, which was 3-15-fold higher than the permissible level (&lt;10 ?g/L). For comparative purposes the biological samples of matched male cancer patient, as referent patients belonging to big city (Hyderabad) who had used municipal treated water with low arsenic levels &lt;10 ?g/L, were also collected. The exposed cancer patients have 2-3-fold higher level of As in both biological samples compared to non-exposed case-matched cancerous male subjects. This study is compelling evidence in support of positive associations between arsenic-contaminated water, food and cigarette with different types of risks of cancer.",
Arsenic,1797810,"Speciation analysis of arsenic compounds by capillary electrophoresis on-line coupled with inductively coupled plasma mass spectrometry using a novel interface Abstract: In this work, a capillary electrophoresis (CE) coupled with inductively coupled plasma mass spectrometer (ICP-MS) system was developed for the simultaneous determination of ten arsenic compounds including arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, 3-nitro-4-hydroxyphenylarsonic acid, o-Arsanilic acid, p-ureidophenylarsonic acid, and 4-nitrophenylarsonic acid. The CE-ICP-MS system was hyphenated by a novel and high efficient interface which was directly used as the nebulizer. The separation was achieved on a 100cm length×50?m ID fused-silica capillary. Analytical conditions such as electrophoretic buffer composition, concentration and pH value, separation voltage, methanol concentration in the sheath flow liquid and sample injection time were optimized. Baseline separation of the ten arsenic species was achieved using an electrophoretic buffer consisting of 12mM NaH2PO4 and 8mM HBO3 at pH 9.20 with an applied voltage of +30kV. The detection limits of the ten arsenic compounds ranged from 0.9 to 3.0ngAsg(-1), corresponding to absolute detection limits in the range of 19-65fg As and the relative standard deviations (RSD, n=5) were below 1.5%, 5.7% and 4.8% for migration time, peak height and peak area, respectively. This method was successfully applied to determine various arsenicals in two certified reference materials (TORT-2 and DORM-3) and environmental samples such as ground water samples, herbal plants and chicken meat.",
Arsenic,1797832,"Arsenic exposure and impaired lung function. Findings from a large population-based prospective cohort study Abstract: Background: Exposure to arsenic through drinking water has been linked to respiratory symptoms, obstructive lung diseases and mortality from respiratory diseases. Limited evidence for the deleterious effects on lung function exists among individuals exposed to a high dose of arsenic. Methods: In 950 individuals who presented with any respiratory symptom among a population-based cohort of 20,033 adults, we evaluated the association between arsenic exposure, measured by well water and urinary arsenic concentrations measured at baseline, and post-bronchodilator administered pulmonary function assessed during follow-up. Results: For every one standard deviation (SD) increase in baseline water arsenic exposure, we observed a lower level of forced expiratory volume in 1 second (FEV1) (-46.5ml, p<0.0005) and forced vital capacity (FVC) (-53.1ml, p<0.01) in regression models adjusted for age, gender, body mass index, smoking, socioeconomic status, betel nut use, and arsenical skin lesions status. Similar inverse relationships were observed between baseline urinary arsenic and FEV1 (-48.3ml, p<0.005) and FVC (-55.2ml, p<0.01) in adjusted models. Our analyses also demonstrated a dose-related decrease in lung function with increasing levels of baseline water and urinary arsenic. This association remained significant in never smokers, individuals without skin lesions, and was stronger in male smokers. Among male smokers and individuals with skin lesions, every one SD increase in water arsenic was related to a significant reduction of FEV1 (-74.4ml, p<0.01 and -116.1ml, p<0.05) and FVC (-72.8ml, p=0.02 and -146.9ml, p=0.004), respectively. Conclusion: This large population-based study confirms that arsenic exposure is associated with impaired lung function and the deleterious effect is evident at low- to moderate-dose range.",
Arsenic,2088516,"Effects of using arsenic-iron sludge wastes in brick making Abstract: The arsenic-iron sludge generated in most of the treatment systems around the world is discharged into the nearest watercourse, which leads to accumulative rise of arsenic and iron concentrations in water. In this study, attempts were made to use the arsenic-iron sludge in making bricks and to analyze the corresponding effects on brick properties. The water treatment plant sludge is extremely close to brick clay in chemical composition. So, the sludge could be a potential substitute for brick clay. This study involved the addition of sludge with ratios 3%, 6%, 9% and 12% of the total weight of sludge-clay mixture. The physical and chemical properties of the produced bricks were then determined and evaluated and compared to control brick made entirely from clay. Results of different tests indicated that the sludge proportion and firing temperature were the two key factors in determining the quality of bricks. The compressive strength of 3%, 6%, 9% and 12% sludge containing brick samples were found to be 14.1MPa, 15.1MPa, 9.4MPa and 7.1MPa, respectively. These results indicate that the compressive strength of prepared bricks initially increased and then decreased with the increase of sludge proportion. Leaching characteristics of burnt bricks were determined with the variation of pH at a constant temperature. The optimum amount of sludge that could be mixed with clay to produce good bonding of clay-sludge bricks was found to be 6% (safely maximum) by weight.",
Arsenic,1329847,"Down-regulation of glutaminase C in human hepatocarcinoma cell by diphenylarsinic acid, a degradation product of chemical warfare agents Abstract: In a poisonous incident in Kamisu, Japan, it is understood that diphenylarsinic acid (DPAA) was a critical contaminant of ground water. Most patients showed dysfunction of the central nervous system. To understand the overall mechanism of DPAA toxicity and to gain some insight into the application of a remedy specific for intoxication, the molecular target must be clarified. As an approach, a high throughput analysis of cell proteins in cultured human hepatocarcinoma HpG2 exposed to DPAA was performed by two-dimensional electrophoresis (2-DE). Four proteins, which were up- and down-regulated by exposure of cultured HepG2 cells to DPAA, were identified. They were chaperonin containing TCP-1 (CCT) beta subunit, aldehyde dehydrogenase 1 (ALDH1), ribosomal protein P0 and glutaminase C (GAC). Of these, GAC was the only protein that was down-regulated by DPAA exposure, and cellular expression levels were reduced by DPAA in a concentration- and time-dependent manner. Decrease in cellular GAC levels was accompanied by decreased activity of the enzyme, phosphate-activated glutaminase (PAG). Decreased expression of GAC by DPAA was also observed in human cervical carcinoma HeLa and neuroblastoma SH-SY5Y cells. By contrast, no significant changes in GAC protein expression were observed when cells were incubated with arsenite [iAs (III)] and trivalent dimethylarsinous acid [DMA (III)]. In the central nervous system, GAC plays a role in the production of the neurotransmitter glutamic acid. Selective inhibition of GAC expression by DPAA may be a cause of dysfunction of glutamatergic neuronal transmission and the resultant neurological impairments.",
Arsenic,1597384,"Removal of arsenic from aqueous environments using Moringa peregrina seed extract as a natural coagulant Abstract: Arsenic is considered as one of the most hazardous elements for the living Organisms and its presence in natural waters,, can result in serious environmental problems. In this study, Moringa peregrina seed extract ability in a batch system to remove arsenate from aqueous solutions was investigated. The effects of major operating variable such as coagulant dose (0.1-5 mL L-1) and pH (2-11) were investigated The optimum pH for removal of arsenic by coagulation using Moringa peregrina seed extract was 6 and the highest removal was found to he 98.61, 99.032 and 98.976% at initial arsenic(V) concentration 100, 200 and 500 mu g L-1 respectively, as a result of precipitation, co-precipitation and adsorption mechanisms. According to achieved results, it was defined that Moringa peregrina seed extract not only was an inexpensive coagulant but also a quite effective factor in removal of arsenic(V)from aqueous environments",
Arsenic,1019889,"Groundwater arsenic contamination, its health impact and mitigation program in Nepal Abstract: About 47% of Nepal's total population is living in Terai region and 90% of them are relying on groundwater as their major source of drinking water. About 200,000 shallow tubewells have been installed by different agencies in 20 Terai districts, serving 11 million people. Recently, arsenic contamination of groundwater has been recognized as a public health problem in Nepal. This has sensitized government, national and international nongovernment organizations working on water quality sector to carry out water quality assessment for arsenic in the affected communities. So far, 15,000 tubewells has been tested where 23% samples exceeded World Health Organization guideline value of 10 microg/L and 5% exceeded &quot;Nepal Interim Arsenic Guideline&quot; of 50 microg/L. It is estimated that around 0.5 million people in Terai are living at risk of arsenic poisoning (&gt;50 microg/L). Some recent studies have reported the prevalence of dermatosis related to arsenicosis from 1.3 to 5.1% and the accumulation of arsenic in biological samples like hair and nail much higher than the acceptable level. Though some steps are being taken by government and private organizations to combat the problem, it has not been able to cover all the affected communities. Nepal still needs more research work on arsenic occurrence and effects and mitigation programs simultaneously.",
Arsenic,1337823,"Regular aerobic exercise protects against impaired fasting plasma glucose-associated vascular endothelial dysfunction with aging Abstract: In the present study, we tested the hypothesis that age-associated vascular endothelial dysfunction is exacerbated by IFG (impaired fasting plasma glucose) and that regular aerobic exercise prevents this effect. Data were analysed from a cohort of 131 non-smoking men and women without overt clinical disease. Compared with young adult controls (age=24±1 years, n=29; values are means±S.E.M.), brachial artery FMD (flow-mediated dilation), a measure of conduit artery EDD (endothelium-dependent dilation), was 33% lower [7.93±0.33 against 5.27±0.37%? (% change), P&lt;0.05] in MA/O (middle-aged/older) adults with NFG (normal fasting plasma glucose) (?99 mg/dl, 62±1 years, n=35). In MA/O adults with IFG (100-125 mg/dl, 64±1 years, n=28), FMD was 30% lower (3.37±0.35%?) than in their peers with NFG and 58% lower than young controls (P&lt;0.05). Brachial artery FMD was greater (6.38±0.35%?) in MA/O adults with NFG who regularly performed aerobic exercise (&gt;45 min/day for ?5 days/week, 62±1 years, n=23) compared with their non-exercising peers and only slightly less than young controls (P&lt;0.05). Most importantly, FMD was completely preserved in MA/O adults with IFG who regularly performed aerobic exercise (6.99±0.69%?, 65±1 years, n=16). In the pooled sample, fasting plasma glucose was inversely related to FMD (r=-0.42, P&lt;0.01) and was the strongest independent predictor of FMD (R2=0.32). Group differences in FMD were not affected by other subject characteristics or brachial artery properties, including brachial artery dilation to sublingual NTG (nitroglycerine, i.e. endothelium-independent dilation). IFG exacerbates age-associated vascular endothelial dysfunction and this adverse effect is completely prevented in MA/O adults who regularly perform aerobic exercise.",
Arsenic,627276,"Chronic arsenic toxicity from drinking tubewell water in rural West Bengal Abstract: Hepatic damage caused by chronic exposure to arsenic has been frequently described. Here we report on 13 patients from West Bengal, India, who consumed large amounts of arsenic in drinking water. An epidemiological investigation of the study area showed evidence of chronic arsenical dermatosis and hepatomegaly in 62 (92.5%) of 67 members of families who drank contaminated water (arsenic level, 0.2-2 mg/l). In contrast, only six (6.25%) of 96 persons from the same area who drank safe water (arsenic level, <0.05 mg/l) had non-specific hepatomegaly, while none had skin lesions. Hepatomegaly occurred in all the 13 patients who were studied in detail, although five had splenomegaly. Biopsy of samples of liver from these patients revealed various degrees of fibrosis and expansion of the portal zone that resembled non-cirrhotic portal fibrosis (NCPF).",
Arsenic,2278882,"Kinetics, intermediates and acute toxicity of arsanilic acid photolysis Abstract: Arsanilic acid (4-amino phenyl arsenic acid, ASA) is widely used in poultry production as feed additives, while most of ASA in the feed is excreted in the animal manure and released into the environment. However, the environmental behaviors of ASA were not well understood. In the present study, the photolysis behaviors of ASA and the toxicity of its metabolites to luminescent bacterium were studied. The results showed that ASA could be photodegraded and this process was strongly affected by solution pH, humic acid and dissolved oxygen. Upon UV irradiation for 360min, ASA could be completely eliminated, but the reduction of total organic carbon (TOC) was not significant. In addition, NH4+ ions and inorganic arsenic including arsenite and arsenate were identified as the predominant end-products. The conversion of ASA included both direct and indirect photolysis involving radicals, and its possible photolysis pathways were proposed on the basis of the identified intermediates. Unfortunately, higher adverse effects of the conversion products of ASA on bacteria were observed during the photolysis reaction. The results of present study might be helpful for assessing the environmental persistence and risks of ASA.",
Arsenic,1354118,Professor Yao-Zeng Huang - An Active Pioneer in the Newly Emerged Areas of Organic Chemistry Abstract: ,
Arsenic,1340102,"Whole-cell configuration of the patch-clamp technique in the hERG channel assay to predict the ability of a compound to prolong QT interval Abstract: In vitro electrophysiological safety studies have become an integral part of the drug development process since, in many instances, compound-induced QT prolongation has been associated with a direct block of human ether-a-go-go-related gene (hERG) potassium channels or its native current, the rapidly activating delayed rectifier potassium current (I(Kr)). Therefore, the in vitro hERG channel patch-clamp assay is commonly used as an early screen to predict the ability of a compound to prolong QT interval. The protocol described in this unit is designed to assess the effects of new chemical entities after acute or long-term exposure on the amplitude of I(Kr) in human embryonic kidney 293 (HEK293) cells stably transfected with the hERG channel (whole-cell configuration of the patch-clamp technique). Examples of results obtained with terfenadine, arsenic, pentamidine, erythromycin, and sotalol are provided for illustrative purposes.",
Arsenic,1241252,"The effectiveness of arsenic remediation from groundwater in a private home Abstract: Private wells are the source of drinking water for approximately 15% of households in the United States, but these wells are not regulated or monitored by government agencies. The well waters can contain arsenic, a known carcinogen that occurs in groundwater throughout the nation at concentrations that can exceed the Maximum Contaminant Level defined by the U.S. Environmental Protection Agency (10 ppb). In order to reduce arsenic exposure, homeowners can either rely on bottled water for drinking or install in-house water treatment systems for arsenic removal. Here, we document the arsenic levels associated with these options. We examined 24 different major bottled water brands and found that all have arsenic levels <1.5 parts per billion (ppb), and more than half have levels below our measurement detection limit of 0.005 ppb. For in-house treatment systems, we examined the performance of arsenic removal by point-of-use reverse osmosis filtration, and by whole-house and point-of-use filters containing granulated ferric oxide. Our results show that long-term (2 years) filtration with granulated ferric oxide reduced arsenic in well water from an initial concentration of 4 to 9 ppb down to <0.005 ppb, validating this technology as an effective form of arsenic remediation for private homes.",
Arsenic,2337118,"Total arsenic in rice milk Abstract: Rice milk and its by-products were tested for total arsenic concentration. Total arsenic concentration was determined using graphite-furnace atomic absorption spectrometry. The arsenic concentrations ranged from 2.7 +/- 0.3 to 17.9 +/- 0.5 mu gL(-1). Rice milk and its by-products are not clearly defined as food, water or milk substitute. The US Environmental Protection Agency (EPA), the European Union (EU) and the World Health Organization (WHO) have set a level of 10 mu gL(-1) for total arsenic concentrations in drinking water. The EU and the US regulatory agencies do not provide any guidelines on total arsenic concentrations in foods. This study provides us with a starting point to address this issue in the State of Mississippi, USA.",
Arsenic,2345810,"Analysis of essential elements in Pito--A cereal food drink and its brands by the single-comparator method of neutron activation analysis Abstract: Instrumental neutron activation analysis using the single-comparator method has been used for the multielement determination of essential elements in two main types of Pito brewed locally in Ghana. The precision and accuracy of the analytical method was validated and found to be within 10%. In all, eight different brands of Pito depending on the type of cereal crop used in brewing were analyzed for 13 different elements (Al, As, Ba, Cl, Co, Cu, Fe, K, Mg, Mn, Na, Si, and Zn). It was observed that all brands were particularly enriched in nutrient elements Cl, Mg, and K. The rest were generally found in varying concentrations. As these elements are bioavailable in natural form, perhaps in combination with organic constituents, they are likely to be easily digested and assimilated by the human body. Arsenic, a toxic element, was found in insignificant amounts suggesting that it was within safe limits.",
Arsenic,627247,"Human epidermal cell protein responses to arsenite treatment in culture Abstract: Study of the responses of target cells in culture is anticipated to help understand the mechanisms by which inorganic arsenic causes pathological effects in vivo. Treatment of human epidermal cells with arsenic has been shown to produce a myriad of changes in gene transcription. Present work focused on finding the extent of arsenite-induced changes in the protein pattern and whether global effects on protein sulfhydryls were evident. First, examining the profile of protein expression by twodimensional gel electrophoresis indicated that ?40% of the 300 distinct protein spots that were monitored changed by at least two-fold in amount all through a 9-day exposure period. Second, examining soluble extracts of the treated cells by Activated Thiol Sepharose column chromatography gave little indication of change in the overall protein thiol content. Finally, among the 10 proteins identified that showed prominent changes in amount as a result of treatment for 1 or 4 days, enzymes of the glycolytic pathway were seen to be substantially elevated as a result of treatment, suggesting decreased utilization by the cells of oxidative phosphorylation. Since these changes were more conspicuous at the protein level than in previous transcriptional studies, the results emphasize the importance of proteomic analysis to complement transcriptional analysis of cell responses to perturbation by arsenic.",
Arsenic,2279301,"Methodology for assessing thioarsenic formation potential in sulfidic landfill environments Abstract: Arsenic leaching and speciation in landfills, especially those with arsenic bearing waste and drywall disposal (such as construction and demolition (C&amp;D) debris landfills), may be affected by high levels of sulfide through the formation of thioarsenic anions. A methodology using ion chromatography (IC) with a conductivity detector was developed for the assessment of thioarsenic formation potential in sulfidic landfill environments. Monothioarsenate (H2AsSO3(-)) and dithioarsenate (H2AsS2O2(-)) were confirmed in the IC fractions of thioarsenate synthesis mixture, consistent with previous literature results. However, the observation of AsSx(-) (x=5-8) in the supposed trithioarsenate (H2AsS3O(-)) and tetrathioarsenate (H2AsS4(-)) IC fractions suggested the presence of new arsenic polysulfide complexes. All thioarsenate anions, particularly trithioarsenate and tetrathioarsenate, were unstable upon air exposure. The method developed for thioarsenate analysis was validated and successfully used to analyze several landfill leachate samples. Thioarsenate anions were detected in the leachate of all of the C&amp;D debris landfills tested, which accounted for approximately 8.5% of the total aqueous As in the leachate. Compared to arsenite or arsenate, thioarsenates have been reported in literature to have lower adsorption on iron oxide minerals. The presence of thioarsenates in C&amp;D debris landfill leachate poses new concerns when evaluating the impact of arsenic mobilization in such environments.",
Arsenic,1359970,Sputum cytology of smelter workers exposed to arsenic and sulfur dioxide Abstract: HEEP COPYRIGHT: BIOL ABS. ABSTRACT CIGARETTE SMOKING,
Arsenic,1337536,"Effect of co-existing copper and calcium on the removal of As(V) by reused aluminum oxides Abstract: Among the various heavy metals, arsenic is frequently found in abandoned mine drainage and the environmental fate of arsenic in real aqueous solutions can be highly dependent on the presence of co-existing ions. In this study, removal of arsenate through adsorption on the reused aluminum oxide or through precipitation was investigated in a single and in a binary system as a function of pH and concentration. Different removal behaviors of arsenate were observed in the presence of different cations as well as a variation of the molar ratios of arsenate to cations. Co-operative effects on arsenate removal by precipitation in solution occurred with an increase of copper concentration, while a decrease of arsenate removal resulted in increasing calcium concentration. It was observed that the arsenate removal in the presence of calcium would be highly dependent on the molar ratios of both elements.",
Arsenic,628046,"Assessment of lymphocyte subpopulations and cytokine secretion in children exposed to arsenic Abstract: Exposure of several human populations to arsenic has been associated with a high incidence of detrimental dermatological and carcinogenic effects. To date, studies examining the immunotoxic effects of arsenic in humans, and specifically in children, are lacking. Therefore, we evaluated several parameters of immunological status in a group of children exposed to arsenic through their drinking water. Peripheral blood mononuclear cells (PBMCs) of 90 children (6 to 10 years old) were collected. Proportions of lymphocyte subpopulations, PBMC mitogenic proliferative response, and urinary arsenic levels were evaluated. Increased urine arsenic levels were associated with a reduced proliferative response to phytohemaglutinin (PHA) stimulation (P=0.005), CD4 subpopulation proportion (P=0.092), CD4/CD8 ratio (P=0.056), and IL-2 secretion levels (P=0.003). Increased arsenic exposure was also associated with an increase in GM-CSF secretion by mononucleated cells (P=0.000). We did not observe changes in CD8, B, or NK cell proportions, nor did we observe changes in the secretion of IL-4, IL-10, or IFN-gamma by PHA-activated PBMCs. These data indicate that arsenic exposure could alter the activation processes of T cells, such that an immunosuppression status that favors opportunistic infections and carcinogenesis is produced together with increased GM-CSF secretion that may be associated with chronic inflammation.",
Arsenic,1508705,"Evaluation of high levels of fluoride, arsenic species and other physicochemical parameters in underground water of two sub districts of Tharparkar, Pakistan: A multivariate study Abstract: In present study total arsenic, inorganic arsenic species and fluoride ion contaminations in underground water of Diplo and Chachro sub district of Tharparkar, Pakistan were investigated. The concentrations of total As, inorganic As species, F(-) and others physicochemical parameters were reported in terms of basic statistical parameters, principal component analysis, cluster analysis, sodium absorption ratio and saturation indices. The As(3+) was determined by cloud point extraction using ammonium pyrrolidinedithiocarbamate (APDC) as complexing reagent, and complex was extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114; after centrifugation the surfactant-rich phase was diluted with 0.1 mol/L HNO(3) in methanol. While total inorganic arsenic (iAs) was determined by solid phase extraction using titanium dioxide (TiO(2)) as an adsorbent, after centrifugation, the solid phase was prepared to be slurry for determination. The extracted As species were determined by electrothermal atomic absorption spectrometry. The concentration of As(5+) in the water samples was calculated by the difference of the total iAs and As(3+), while F(-) and other anions were determined by ion chromatography. The positive correlation of F(-) and As species with Na(+) and HCO(3)(-) showed that the water with high salinity and alkalinity stabilized the As species and F(-) in the groundwater. The positive correlation (r = 0.640, p = 0.671) was observed between total As and it species with F(-). Results showed that underground water samples of these two areas of Tharparkar were severely contaminated with arsenic and fluoride ion, which are exceeded the World Health Organization (WHO) provisional guideline value, and United States Environmental Protection Agency, maximum contaminant level of 0.01 mg/L and 1.5 mg/L, respectively.",
Arsenic,1508603,"A metabolomic investigation on arsenic-induced toxicological effects in the clam Ruditapes philippinarum under different salinities Abstract: Arsenic is an important contaminant in the Bohai marine ecosystem due to the anthropogenic activities. In this work, we investigated the toxicological effects of arsenic in Ruditapes philippinarum under different seawater salinities using NMR-based metabolomics. Under normal salinity (31.1ppt), arsenic decreased the levels of amino acids (glutamate, ?-alanine, etc.), and increased the levels of betaine and fumarate. The metabolic biomarkers including decreased threonine, histidine, ATP and fumarate were found in the muscles of arsenic-treated clams under medium salinity (23.3ppt). However, only elevated ATP and depleted succinate were detected in the arsenic-exposed clam samples under low salinity (15.6ppt). These differential metabolic biomarkers indicated that arsenic could induce osmotic stress and disturbance in energy metabolism in clam under normal and medium salinities. However, arsenic caused only disturbance in energy metabolism in clam under low salinity. Overall, our results demonstrated that seawater salinity could influence the toxicological effects of arsenic.",
Arsenic,2279511,"Quantifying missing annual emission sources of heavy metals in the United Kingdom with an atmospheric transport model Abstract: An atmospheric chemical transport model was adapted to simulate the concentration and deposition of heavy metals (arsenic, cadmium, chromium, copper, lead, nickel, selenium, vanadium, and zinc) in the United Kingdom. The model showed that wet deposition was the most important process for the transfer of metals from the atmosphere to the land surface. The model achieved a good correlation with annually averaged measurements of metal concentrations in air. The correlation with measurements of wet deposition was less strong due to the complexity of the atmospheric processes involved in the washout of particulate matter which were not fully captured by the model. The measured wet deposition and air concentration of heavy metals were significantly underestimated by the model for all metals (except vanadium) by factors between 2 and 10. These results suggest major missing sources of annual heavy metal emissions which are currently not included in the official inventory. Primary emissions were able to account for only 9%, 21%, 29%, 21%, 36%, 7% and 23% of the measured concentrations for As, Cd, Cr, Cu, Ni, Pb and Zn. A likely additional contribution to atmospheric heavy metal concentrations is the wind driven re-suspension of surface dust still present in the environment from the legacy of much higher historic emissions. Inclusion of two independent estimates of emissions from re-suspension in the model was found to give an improved agreement with measurements. However, an accurate estimate of the magnitude of re-suspended emissions is restricted by the lack of measurements of metal concentrations in the re-suspended surface dust layer.",
Arsenic,1366337,"Determination of arsenic and selenium in environmental samples by hydride generation-direct current plasma-atomic emission spectrometry Abstract: Hydride generation-direct current plasma-atomic emission spectrometry has been shown to be a simple and rapid procedure for the determination of arsenic and selenium in environmental samples, offering acceptable accuracy and precision. Simplex optimization of the operating parameters showed typical DCP operating conditions and a hydrochloric acid concentration of 6 mol liter?1 to be optimal. The detection limit for both elements was 4 ng ml?1.",
Arsenic,1015739,"Comparison of three sequential extraction procedures for fractionation of arsenic from highly polluted mining sediments Abstract: Three sequential extraction procedures were evaluated for the study of fractionation of arsenic in environmental solid samples. The procedures considered were as follows: i) the standardized and widely recognised BCR procedure, conceived for the study of the partitioning of heavy metals; ii) the procedure developed by Manful, who adapted a phosphorus scheme for arsenic fractionation; and iii) a novel sequential extraction scheme especially devised for arsenic. The efficiency and suitability of these methods and the corresponding extraction steps for partitioning arsenic obtained from the most important solid forms were tested by application of the methods to real sediment samples heavily polluted by mining activity. Results showed the BCR scheme was inappropriate for arsenic fractionation. The procedure could, nevertheless, be a first approach for the assessment of arsenic partitioning, because its first extraction step can be regarded as adequate for the estimation of the most easily mobilizable arsenic. Although the Manful scheme results in a more differentiated arsenic pattern, some drawbacks arise from the lack of selectivity of some of the reagents used, for example overlapping of specific target phases, overestimation of adsorbed arsenate because of inadequate coprecipitation processes, and the inability to discriminate among amorphous and crystalline oxyhydroxides which are mainly responsible for arsenic retention. The novel procedure achieves the most suitable arsenic fractionation, because the main phases retaining arsenic are selectively targeted according to mobilization potential. In addition, the simplicity of its extraction steps would enable automation in a continuous flow scheme.",
Arsenic,710862,"Assessment of low ABSPI among arsenic exposed and non-exposed populations: A pilot study Abstract: This cross-sectional study was carried out to assess and compare Ankle Brachial Systolic Pressure Index (ABSPI) amongst 120 arsenic exposed and 120 non-exposed populations of Samta village in Bangladesh. Abnormal ABSPI was more prevalent in arsenic exposed (13.3%) than in non-exposed (2.5%) group. The prevalence of abnormal ABSPI for respondents when adjusted for age, sex, BMI, blood pressure status and diabetic status, the prevalence remain significantly different. The findings suggest that those exposed to arsenic have increased chance of having abnormal ABSP and hence increased chance of peripheral arterial disease in Bangladesh.",
Arsenic,2343479,"Predictive Value of Myocardial Delayed Enhancement in Duchenne Muscular Dystrophy Abstract: In other cardiomyopathies, cardiac magnetic resonance imaging (CMR)-derived myocardial delayed enhancement (MDE), a marker of myocardial fibrosis, is a risk factor for sudden cardiac death (SCD). In Duchenne muscular dystrophy (DMD), the prognostic value of MDE for ventricular arrhythmias and death is unknown. This study aimed to evaluate associations between MDE and electrocardiographic (ECG) changes, ventricular remodeling, risk of arrhythmias, and death in DMD. This retrospective study included all subjects with DMD who had undergone a CMR between January 2006 and December 2011 and had available ECG and 24-h Holter records from the same period. Left ventricular (LV) MDE was semiquantitatively graded from 0 to 4. Comparisons of demographic and clinical characteristics between MDE and no-MDE groups were made. Cox regression analysis was performed to assess factors associated with death. This study investigated 32 boys with a median age of 13.8 years (range, 7.2-17.4 years) and found MDE present in 25 (78 %) of the boys. Compared with the no-MDE subjects, the MDE subjects were older (15.7 ± 3.3 vs 12.1 ± 4.8 years) and had a wider QT dispersion (QTd: 74 ± 30 vs 55 ± 33 ms), a higher incidence of ventricular tachycardia (40 vs 0 %), a lower LV ejection fraction (46 ± 12 vs 56 ± 9 %), a larger LV end-diastolic volume (124 ± 58 vs 68 ± 14 ml/m(2)), and a larger end-systolic volume (57 ± 29 vs 28 ± 10 ml/m(2)) (p &lt; 0.05 for all). During the study period, six of the subjects (19 %) died. The factors associated with mortality were increased age, advanced grade of MDE, higher LV end-systolic volume, lower LV ejection fraction, use of beta-blockers, and ventricular tachycardia. Myocardial fibrosis detected by CMR is an independent predictor of adverse cardiac remodeling, ventricular arrhythmias, and death in DMD. Cardiac MRI using MDE can be applied as a screening tool to detect patients at risk for ventricular arrhythmias, more advanced disease, adverse LV remodeling, and death.",
Arsenic,1026155,"Arsenic ecotoxicology and innate immunity Abstract: Understanding the ecotoxicological effects of arsenic in the environment is paramount to mitigating its deleterious effects on ecological and human health, particularly on the immune response. Toxicological and long-term health effects of arsenic exposure have been well studied. Its specific effects on immune function, however, are less well understood. Eukaryotic immune function often includes both general (innate) as well as specific (adaptive) responses to pathogens. Innate immunity is thought to be the primary defense during early embryonic development, subsequently potentiating adaptive immunity in jawed vertebrates, whereas all other eukaryotes must rely solely on the innate immune response throughout their life cycle. Here, we review the known ecotoxicological effects of arsenic on general health, including immune function, and propose the adoption of zebrafish as a vertebrate model for studying such effects on innate immunity.",
Arsenic,628425,"Effects of arsenic on telomerase and telomeres in relation to cell proliferation and apoptosis in human keratinocytes and leukemia cells in vitro Abstract: Telomeres are critical in maintaining chromosome and genomic stability. Arsenic, a human carcinogen as well as an anticancer agent, is known for its clastogenicity. To better understand molecular mechanisms of arsenic actions, we investigated arsenite effects on telomere and telomerase and determined cell growth and apoptosis in HL-60 and HaCaT cells in vitro. Low concentrations (0.1-1 microM in HaCaT and 0.1-0.5 microM in HL-60) of arsenite increased telomerase activity, maintained or elongated telomere length, and promoted cellular proliferation. High concentrations (>1-40 microM) of arsenite decreased telomerase activity, telomere length and induced apoptosis. Results from the studies comparing cell lines with and without telomerase activity suggested that telomerase was involved in arsenic-induced apoptosis. The spin trap agent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was effective in protecting the arsenite-induced telomere attrition and apoptosis, suggesting that reactive oxygen species may play an important role in the shortening of telomeres and apoptosis induced by arsenic. These findings suggest the carcinogenic effects of arsenic may be partly attributed to increase in telomerase activity leading to promotion of cell proliferation and its anticancer effects by exerting oxidative stress and leading to telomeric DNA attrition and apoptosis.",
Arsenic,1032002,"Induction of gene amplification by arsenic Abstract: Arsenic is a well-established carcinogen in humans, but there is little evidence for its carcinogenicity in animals and it is inactive as an initiator or tumor promoter in two-stage models of carcinogenicity in mice. Two arsenic salts (sodium arsenite and sodium arsenate) induced a high frequency of methotrexate-resistant 3T6 cells, which were shown to have amplified copies of the dihydrofolate reductase gene. The ability of arsenic to induce gene amplification may relate to its carcinogenic effects in humans since amplification of oncogenes is observed in many human tumors. The inability of arsenic to induce gene mutations may relate to the negative results of arsenic in long-term animal studies and suggests that these experiments may not detect some environmental agents that act late in the carcinogenic process in humans.",
Arsenic,87066,"Toxic trace element reference levels in blood and urine: influence of gender and lifestyle factors Abstract: This study is part of the EURO-TERVIHT project (Trace Element Reference Values in Human Tissues) which aims at establishing reference intervals for trace elements in blood, urine and other human tissues. In this study, reference intervals (0.05-0.95 fractiles) were estimated for lead in blood (105-529 nmol/l for men, 80-340 nmol/l for women), manganese in blood (100-271 nmol/l) and arsenic in urine (36-541 nmol/l for men, 21-475 nmol/l for women). Upper reference limits (0.95 fractile) were established for chromium in urine (13 nmol/l), nickel in urine (52 nmol/l) and cobalt in urine (23 nmol/l for men, 31 nmol/l for women). The reference group was a Danish subpopulation (n = 189), age 40-70 years. The influence of gender, age, health status parameters, nutrition and various lifestyle factors was investigated. Urinary arsenic and blood lead levels were found to be higher for men than for women. Arsenic levels also increased with age up to 60 years, and then decreased. Alcohol intake lead to increased arsenic levels in urine as well as blood lead levels. Urinary nickel levels were higher in persons frequently eating porridge and porridge oats.",
Arsenic,627585,"Arsenic induces oxidant stress and NF-kappa B activation in cultured aortic endothelial cells Abstract: Chronic exposure to low levels of environmentally derived arsenite are associated with vascular diseases, such as arteriosclerosis. However, the cellular and molecular mechanisms for vascular disease in response to arsenic are not known. These studies investigated the hypothesis that nonlethal levels of arsenic increase intracellular oxidant levels, promote nuclear translocation of trans-acting factors, and are mitogenic. Incubation of second passage vascular endothelial cells with less than 5 microM arsenite for 4 h increased incorporation of [3H]thymidine into genomic DNA, while higher concentrations failed to stimulate or inhibit DNA synthesis. Within 1 h following addition of noncytotoxic concentrations of arsenite, oxidants accumulated and thiol status increased. During this time period, there was increased nuclear retention of NF-kappa B binding proteins and nuclear translocation of NF-kappa B also occurred in response to 100 microM H2O2. Supershift analysis demonstrated that p65/p50 heterodimers accounted for the majority of proteins binding consensus kappa B sequences in cells treated with arsenite or oxidants. The antioxidants, N-acetylcysteine or dimethylfumaric acid, increased intracellular thiol status and prevented both oxidant formation and translocation of NF-kappa B binding proteins in response to arsenite. These data suggest that arsenite initiates vascular dysfunction by activating oxidant-sensitive endothelial cell signaling.",
Arsenic,8614,"Arsenic intoxication from well water in the United States Abstract: Perhaps no substance has had historical notoriety equal to that of arsenic. Nevertheless, its use in medicinal compounds has been widespread since antiquity, and occupational exposure has been common, particularly in the first half of this century. Its greatest use has been in the production of pesticides and herbicides, and a substantial number of accidental deaths have occurred from ingestion of these substances. Despite its ubiquity in the environment, arsenic intoxication in the United States secondary to a contaminated water supply is rare. In the 11 cases reported below, acute and subacute arsenic intoxication was related to ingestion of well water.",
Arsenic,1579374,Novel Calix[4]arene-based Amberlite XAD-4 Modified Resin for As(III) Removal from Water Abstract: ,
Arsenic,2337108,"Multiple assessment of the soil cover in the area of natural monuments Tra-Tau and Yurak-Tau monadnocks under conditions of technogenic loads Abstract: The soil cover of Tra-Tau and Yurak-Tau shikhans (monadnocks) has been examined. Leached and typical medium-deep chernozems are developed on colluvial fans on the footslopes and on the lower parts of slopes, whereas typical calcareous thin slightly and moderately gravelly chernozems are developed on the upper and medium parts of slopes. The leached and typical chernozems of the footslopes correspond to zonal soils of the adjacent plain areas, though they have some specific features related to the local topographic conditions. These soils are somewhat thinner than plain chernozems and are characterized by the perfect granular water-stable structure, the high content of humus of the humate type, the high content of exchangeable cations, strong acid-base buffering, and high enzymatic activity. These features predetermine their high tolerance towards technogenic impacts. The concentrations of highly hazardous substances of the first toxicity class (mercury, arsenic, lead, and cadmium) and of moderately hazardous substances of the second toxicity class (copper, zinc, and nickel), as well as the concentrations of low-hazardous elements (manganese and iron) in these soils do not exceed provisional maximum permissible concentrations of these substances in soils irrespectively of the slope aspect. No changes in the physicochemical and biological properties of the soils under the impact of technogenic loads from Sterlitamak industrial center have been identified.",
Arsenic,2279164,"Arsenic (As), antimony (Sb), and lead (Pb) availability from Au-mine Technosols: a case study of transfer to natural vegetation cover in temperate climates Abstract: Soils from old Au-mine tailings (La Petite Faye, France) were investigated in relation to the natural vegetation cover to evaluate the risk of metals and metalloids (Pb, As, Sb) mobilizing and their potential transfer to native plants (Graminea, Betula pendula, Pteridium aquilinum, Equisetum telmateia). The soils are classified as Technosols with high contamination levels of As, Pb, and Sb. The single selective extractions tested to evaluate available fraction (CaCl2, acetic acid, A-Rhizo, and DTPA) showed low labile fractions (&lt;5 % of bulk soil contents), but still significant levels were observed (up to 342.6 and 391.9 mg/kg for As and Pb, respectively) due to the high contamination levels of soils. Even at high soil contaminations (considered as phytotoxic levels for plants), translocation factors for native plants studied are very low resulting in low concentrations of As, Sb, and Pb in their aerial part tissues. This study demonstrates the important role of (1) native plant cover in terms of &quot;stabilization&quot; of these contaminants, and (2) the poor effectiveness of extraction procedures used for this type of soil assemblages, i.e., rich in specific mineral phases.",
Arsenic,1347884,"Identifying groundwater arsenic contamination mechanisms in relation to arsenic concentrations in water and host rocks Abstract: Leaching and oxidation of high arsenic (As) host rocks tend to be induced by circulation of deep geothermal waters, which increase As concentration in shallow groundwater. The purpose of this study is to identify the mechanism of groundwater As contamination in relation to leaching and oxidation along the border between the South Minahasa and Bolaang Mongondow districts, North Sulawesi, Indonesia. This region contains Miocene sedimentary rock-hosted disseminated gold deposits associated with hydrothermal alteration in a fault zone. Abnormally high As concentrations were observed in hot and cold springs and in surrounding shallow groundwater for a total mineralization area of 8 × 10 km2. Two methods were adopted in this study: (1) microscopic and spectroscopic analyses of rock samples for mineral identification and (2) geostatistics for spatial modeling of As concentrations in groundwater. Jarosite was identified as the chief fill mineral in rock defects (cracks and pores). The presence of this mineral may indicate release of As into the environment, as can occur as an alteration product derived from oxidation and leaching of pyrite, As-rich pyrite or sulfide minerals by geothermal waters. Moreover, As concentrations in groundwater were estimated using geostatistics for spatial modeling. The co-kriging map identified local anomalies in groundwater As concentrations over the permissible limit (10 ppb). Such anomalies did not appear through ordinary kriging. Integration of the results indicates that As contamination in shallow groundwater probably is controlled by heterogeneous distributions of jarosite and variations in intensity and extent of hydrothermal activities.",
Arsenic,628454,"Transplacental carcinogenicity of inorganic arsenic in the drinking water: Induction of hepatic, ovarian, pulmonary, and adrenal tumors in mice Abstract: Arsenic is a known human carcinogen, but development of rodent models of inorganic arsenic carcinogenesis has been problematic. Since gestation is often a period of high sensitivity to chemical carcinogenesis, we performed a transplacental carcinogenicity study in mice using inorganic arsenic. Groups (n = 10) of pregnant C3H mice were given drinking water containing sodium arsenite (NaAsO(2)) at 0 (control), 42.5, and 85 ppm arsenite ad libitum from day 8 to 18 of gestation. These doses were well tolerated and body weights of the dams during gestation and of the offspring subsequent to birth were not reduced. Dams were allowed to give birth, and offspring were weaned at 4 weeks and then put into separate gender-based groups (n = 25) according to maternal exposure level. The offspring received no additional arsenic treatment. The study lasted 74 weeks in males and 90 weeks in females. A complete necropsy was performed on all mice and tissues were examined by light microscopy in a blind fashion. In male offspring, there was a marked increase in hepatocellular carcinoma incidence in a dose- related fashion (control, 12%; 42.5 ppm, 38%; 85 ppm, 61%) and in liver tumor multiplicity (tumors per liver; 5.6-fold over control at 85 ppm). In males, there was also a dose-related increase in adrenal tumor incidence and multiplicity. In female offspring, dose-related increases occurred in ovarian tumor incidence (control, 8%; 42.5 ppm, 26%; 85 ppm, 38%) and lung carcinoma incidence (control, 0%; 42.5 ppm, 4%; 85 ppm, 21%). Arsenic exposure also increased the incidence of proliferative lesions of the uterus and oviduct. These results demonstrate that oral inorganic arsenic exposure, as a single agent, can induce tumor formation in rodents and establishes inorganic arsenic as a complete transplacental carcinogen in mice. The development of this rodent model of inorganic arsenic carcinogenesis has important implications in defining the mechanism of action for this common environmental carcinogen. Copyright 2003 Elsevier Science (USA)",
Arsenic,1357904,"An Inexpensive, Portable, Multi-Sampler Abstract: A short term, multi head sampler was described which is useful for evaluating exposures of firefighters to smoke and combustion products. The sampler is able to collect short duration, high volume, multiple simultaneous air samples and is portable, compact, durable, and simple to operate. The author notes that it could also be useful for less extreme conditions such as multiple contaminant sampling of welding fumes, sandblasting areas, or hazardous waste sites. Its development was based on the fact that for fire conditions, sampling time is short, 5 to 10 minutes, and at least twelve distinct sampling media are required to characterize the smoke constituents. The sampler was a modified Dust Buster vacuum cleaner. Six sorbent tubes wrapped with foam rubber weather stripping were inserted into the mouth of the vacuum plenum. Filter cassettes were attached and impingers were taped to the sides of the plenum for support. An oven thermometer was glued to the front face. A spring loaded timer was added to switch off automatically after a preselected time interval. The apparatus fits into a carrying holster clipped onto the self contained breathing apparatus chest cross strap of the firefighter's uniform. In field tests, the device successfully monitored simultaneously seven classes of contaminants present in concentrations ranging over several orders of magnitude, even parts per billion. The device could be assembled for under 135 dollars, excluding filter and sorbent tube cost. It detected amines, glycols, aromatic and aliphatic hydrocarbons, acetic-acid (64197), aldehydes, polychlorinated-biphenyls (1336363), nitrogen-dioxide (10102440), formaldehyde (50000), metals, arsenic (7440382), total particulates, acrolein (107028), hydrogen-cyanide (74908), sulfuric-acid (7664939), hydrochloric-acid (7647010), hydrogen-fluoride (7664393), methane (74828), butane (106978), carbon-monoxide (630080), carbon-dioxide (124389) and oxygen (7782447). The author points out that the device is not safe in terms of source of ignition and should not be used for operations involving flammable liquids.",
Arsenic,1337850,Steroid Hormones and Anthropogenic Contaminants in Poultry Litter Leachate Abstract: ,
Arsenic,2347579,"Assessment of arsenic concentration in stream water using neuro fuzzy networks with factor analysis Abstract: We propose a systematical approach to assessing arsenic concentration in a river through: important factor extraction by a nonlinear factor analysis; arsenic concentration estimation by the neuro-fuzzy network; and impact assessment of important factors on arsenic concentration by the membership degrees of the constructed neuro-fuzzy network. The arsenic-contaminated Huang Gang Creek in northern Taiwan is used as a study case. Results indicate that rainfall, nitrite nitrogen and temperature are important factors and the proposed estimation model (ANFIS(GT)) is superior to the two comparative models, in which 50% and 52% improvements in RMSE are made over ANFIS(CC) and ANFIS(all), respectively. Results reveal that arsenic concentration reaches the highest in an environment of lower temperature, higher nitrite nitrogen concentration and larger one-month antecedent rainfall; while it reaches the lowest in an environment of higher temperature, lower nitrite nitrogen concentration and smaller one-month antecedent rainfall. It is noted that these three selected factors are easy-to-collect. We demonstrate that the proposed methodology is a useful and effective methodology, which can be adapted to other similar settings to reliably model water quality based on parameters of interest and/or study areas of interest for universal usage. The proposed methodology gives a quick and reliable way to estimate arsenic concentration, which makes good contribution to water environment management.",
Arsenic,1020681,"Occupational exposures during routine activities in coal-fueled power plants Abstract: Limited information is available on occupational exposures during routine, nonoutage work activities in coal-fueled power plants. This study evaluated occupational exposures to the principal contaminants in the facilities, including respirable dust (coal dust), arsenic, noise, asbestos, and heat stress. The data were collected over a 3-month period, during the summer of 2001, in 5 facilities that were chosen to be representative of the coal-fueled power plants of a large southeastern power-generating company. Each of the facilities was divided into 5 similar exposure groups based on previous exposure assessments and job tasks performed. From 4 of the 5 facilities, 392 air samples and 302 noise samples were collected with approximately 50 respirable coal dust, 32 arsenic, 15 asbestos, and 70 noise samples from each of the 4 plants. One of the previously surveyed facilities was also evaluated for heat stress, and 1 additional coal-fueled power plant was surveyed for a total of 20 personal heat stress samples. Personal monitors and area WBGT monitors were used. Of the nearly 400 air samples collected, only 1 exceeded the allowable occupational exposure value. For the noise samples, 55 (approximately 18%) were equal to or greater than the Occupational Safety and Health Administration (OSHA) 8-hour hearing conservation program level of 85 dBA, and 12 (approximately 4%) were equal to or greater than the OSHA 8-hour permissible exposure level of 90 dBA. Heat stress monitoring at the facilities indicates that 26% of the 1-hour TWAs were exceeded for one or all of the recommended heat stress limits. The data also concluded that some work sites were above the heat stress ceiling values recommended by the National Institute for Occupational Safety and Health (NIOSH). Four of the 20 employees personally monitored exceeded the recommended limits for heart rate or body core temperature. This suggests there is a potential for heat strain if signs and symptoms are ignored. Recommendations are made to better control the heat stress exposure.",
Arsenic,1019142,"Sensitivity of myelomonocytic leukemia cells to arsenite-induced cell cycle disruption, apoptosis, and enhanced differentiation is dependent on the inter-relationship between arsenic concentration, duration of treatment, and cell cycle phase Abstract: Arsenite treatment has been found to induce clinical remission in patients with acute promyelocytic leukemia. Although the potential therapeutic value of arsenite may lie in triggering apoptosis, it has not been established that cytotoxicity is the sole mechanism of action. We have used a myelomonocytic leukemia cell line (U937) to characterize the concentration-dependent effects of arsenite on cell growth, viability, apoptosis, and differentiation. Arsenite has multiple effects on U937 cells. Low concentrations of arsenite (i.e., &lt; or = 1 microM) potentiate vitamin-D(3)-induced differentiation. Two markers of monocyte differentiation, Mac-1 expression and nitroblue tetrazolium reduction, are increased in arsenite-exposed, D(3)-costimulated cells. Concentrations of arsenite &gt;10 microM rapidly induce the death of cells irrespective of cell cycle phase. Intermediate concentrations of arsenite (i.e., 5 to 10 microM) are cytostatic initially. Cell cycle analysis using elutriated, synchronous cell populations revealed that intermediate concentrations of arsenite delay both G(1) and G(2) transit. G(2) cells appear to be most sensitive to arsenite, in that transit through G(2)/M is more delayed than transit through G(1), and apoptosis is induced in these cells as they emerge from an aberrant G(2)/M. Arsenite-induced apoptosis was caspase-3 dependent. Arsenite-mediated cytotoxicity was reduced in the presence of the broad caspase inhibitor Z-Val-Ala-DL-Asp-fluoromethylketone; however, caspase inhibition did not reverse arsenite-induced cytostasis. Thus, arsenite has multiple effects on U937 cells that are dependent on concentration and cell cycle phase. Specifically, cell cycle transit and differentiation are more sensitive to arsenite than is the induction of apoptosis.",
Arsenic,1070399,"Dietary exposure to trace elements and health risk assessment in the 2nd French Total Diet Study Abstract: Dietary exposure of the French population to trace elements has been assessed in the second national Total Diet Study (TDS). Food samples (n=1319) were collected between 2007 and 2009 to be representative of the whole diet of the population, prepared as consumed, and analyzed. Occurrence data were combined with national individual consumption data to estimate dietary exposure for adults and children mean and high consumers. Compared to the 1st French TDS performed in 2000-2004, exposure is higher for cadmium, aluminium, antimony, nickel, cobalt and lower for lead, mercury and arsenic. For aluminium, methylmercury, cadmium, lead and inorganic arsenic risk cannot be ruled out for certain consumer groups. It still appears necessary to continue undertaking efforts to reduce exposure to these elements. Due to the lack of robust toxicological data and/or speciation analysis in food on chromium, tin, silver and vanadium to perform a risk assessment, data on occurrence and dietary exposure are provided as Supplementary material. In order to minimize nutritional and chemical risks, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) reiterates its recommendation for a diversified diet (food items and origins).",
Arsenic,1021734,"Arsenic disulfide synergizes with the phosphoinositide 3-kinase inhibitor PI-103 to eradicate acute myeloid leukemia stem cells by inducing differentiation Abstract: Although dramatic clinical success has been achieved in acute promyelocytic leukemia (APL), the success of differentiating agents has not been reproduced in non-APL leukemia. A key barrier to the clinical success of arsenic is that it is not potent enough to achieve a clinical benefit at physiologically tolerable concentrations by targeting the leukemia cell differentiation pathway alone. We explored a novel combination approach to enhance the eradication of leukemia stem cells (LSCs) by arsenic in non-APL leukemia. In the present study, phosphatidylinositol 3-kinase /AKT/mammalian target of rapamycin (mTOR) phosphorylation was strengthened after As(2)S(2) exposure in leukemia cell lines and stem/progenitor cells, but not in cord blood mononuclear cells (CBMCs). propidium iodide-103, the dual PI3K/mTOR inhibitor, effectively inhibited the transient activation of the PI3K/AKT/mTOR pathway by As(2)S(2). The synergistic killing and differentiation induction effects on non-APL leukemia cells were examined both in vitro and in vivo. Eradication of non-APL LSCs was determined using the nonobese diabetic/severe combined immunodeficiency mouse model. We found that a combined As(2)S(2)/PI-103 treatment synergized strongly to kill non-APL leukemia cells and promote their differentiation in vitro. Furthermore, the combined As(2)S(2)/PI-103 treatment effectively reduced leukemia cell repopulation and eradicated non-APL LSCs partially via induction of differentiation while sparing normal hematopoietic stem cells. Taken together, these findings suggest that induction of the PI3K/AKT/mTOR pathway could provide a protective response to offset the antitumor efficacy of As(2)S(2). Targeting the PI3K/AKT/mTOR pathway in combination with As(2)S(2) could be exploited as a novel strategy to enhance the differentiation and killing of non-APL LSCs.",
Arsenic,1344078,"Interaction between iron plaque and root border cells ameliorates aluminum toxicity of Oryza sativa differing in aluminum tolerance Abstract: Root border cells (RBCs), which are generated during plant growth and surround the root cap, and iron plaque (IP), ubiquitously formed on the root surfaces of rice, are known to alleviate aluminum (Al) toxicity. To verify the interactive effects of IP and RBCs on ameliorating Al toxicity, two rice cultivars differing in Al resistance were used to compare Al tolerance between cultivars. Additionally, root elongation, Al uptake and RBCs viability were measured as indicators of the effects of Al. The amounts of DCB-extractable Fe and Al on the root surfaces were much higher in the presence of IP than the absence. IP presence significantly decreased Al-induced inhibition of root elongation and Al contents in roots and root tips. The removal of RBCs from the root tips caused a more severe inhibition of root elongation and a higher Al accumulation in rice roots and root tips. Furthermore, root growth inhibition and Al contents in roots and root tips were significantly lower in roots with a combination of IP and RBCs than in roots with IP or RBCs only. The formation of IP on the root surface maintained higher RBCs viability and depressed mucilage exudation in an Al-tolerant rice cultivar. The results suggest that both IP and RBCs ameliorate Al toxicity, and IP has a greater capacity for Al resistance. The combination of IP and RBCs exhibited a synergistic effect associated with Al resistance.",
Arsenic,656689,"Influence of repeated preexposure to arsenic on acetaminophen-induced oxidative stress in liver of male rats Abstract: We evaluated whether repeated arsenic preexposure can increase acetaminophen-induced hepatic oxidative stress. Rats were exposed to arsenic (25 ppm; rat equivalent concentration of maximum groundwater contamination level) via drinking water for 28 days. Next day, they were given single oral administration of acetaminophen (420 or 1000 mg/kg b.w.). Hepatotoxicity was evaluated by assessing serum biomarkers, cytochrome-P450 (CYP) content, CYP3A4- and CYP2E1-dependent enzymes, lipid peroxidation and antioxidants. Arsenic or acetaminophen increased serum ALT and AST activities and depleted CYP. Arsenic decreased, but acetaminophen increased CYP-dependent enzyme activities. These agents independently increased lipid peroxidation and decreased antioxidants. Arsenic did not alter the effects of acetaminophen on serum biomarkers, caused further CYP depletion and decreased acetaminophen-mediated induction of drug-metabolizing enzymes. Arsenic enhanced the lower dose of acetaminophen-mediated lipid peroxidation and glutathione depletion with no further alterations in enzymatic antioxidants. However, arsenic attenuated the higher dose-mediated lipid peroxidation and glutathione depletion with improvement in glutathione peroxidase and glutathione reductase activities, further decrease in catalase and no alterations in superoxide dismutase and glutathione-S-transferase activities. Results show that arsenic preexposure increased the susceptibility of rats to hepatic oxidative stress induced by the lower dose of acetaminophen, but reduced the oxidative stress induced by the higher dose.",
Arsenic,2347617,"Detection and analysis of 12 heavy metals in blood and hair sample from a general population of Pearl River Delta area Abstract: To detect the content of 12 heavy metals in blood and hair sample from a general population of Pearl River Delta area, and to analyze the influence of duration of residence, gender, age, smoking and drinking on the heavy metal content. Use inductively coupled plasma mass spectrometry to detect the content of 12 heavy metals lead (Pb), mercury (Hg), cadmium (Cd), aluminum (Al), arsenic (As), copper (Cu), chrome (Cr), manganese (Mn), nickel (Ni), zinc (Zn), tin (Sn) and antimony (Sb) in blood and hair samples of a total of 50 subjects from a general population, collected by multistage stratified cluster random sampling method. The geometric mean of heavy metal content in blood samples of general population (?g/L): blood aluminum 214.00; blood chrome 92.82; blood manganese 21.43; blood nickel 20.59; blood copper 0.67; blood zinc 11.50; blood arsenic 0.55; blood cadmium 2.45; blood tin 0.00; blood antimony 1.92; blood lead 158.84; and blood mercury 1.19. The geometric mean of heavy metal content in hair samples of general population (?g/g): hair aluminum is 84.65; hair chrome 0.00; hair manganese 2.44; hair nickel 0.61; hair copper 28.49; hair zinc 136.65; hair arsenic 0.75; hair cadmium 0.46; hair tin 1.04; hair antimony 0.05; hair lead 8.97; and hair mercury 0.69. Some heavy metals were correlated with duration of residence, gender, age, smoking and drinking. This was the first time that simultaneously detecting heavy metal content in blood and hair was used to analyze the internal heavy metal burden in resident population of Pearl River Delta area. These data can serve as reference for further research.",
Arsenic,1797752,"Phytofiltration of arsenic and cadmium from the water environment using Micranthemum umbrosum (J.F. Gmel) S.F Blake as a hyperaccumulator Abstract: Arsenic (As) and cadmium (Cd) pollution in water is an important global issue. Phytofiltration is an eco-friendly technology that helps clean up pollutants using ornamental plants, such as Micranthemum umbrosum (J.F. Gmel) S.F. Blake. After a seven-day hydroponic experiment, M. umbrosum removed 79.3-89.5% As and 60-73.1% Cd from 0 to 1.0 microg As mL(-1) and 0.3 to 30.0 microg Cd mL(-1) solutions, respectively. For As treatment, root to stem and stem to leaf translocation factors greater than 1.0 indicated that accumulation of As in leaves was large compared to that in stem and roots. However, the accumulation of Cd in roots was higher than that in the leaves and stem. In addition, M. umbrosum completely removed Cd within three days from 0.38 to around 0 microg mL(-1) Cd in the solution when the plant was exchanged daily. Bio-concentration factors (2350 for As and 3027 for Cd) for M. umbrosum were higher than for other As and Cd phytoremediators. The results show that M. umbrosum can be an effective accumulator of Cd and a hyper-accumulator of As, as it can lower As toxicity to a level close to the limit recommended by the World Health Organization (0.01 microg As mL(-1)).",
Arsenic,1508640,"Tetraarsenic oxide and cisplatin induce apoptotic synergism in cervical cancer Abstract: Tetraarsenic oxide (As4O6, TAO) is a new arsenic compound that inhibits cell growth and induces apoptosis in human cervical cancer cell lines. In the present study, we report that the growth of tumor cells (CaSki) was inhibited by treatment with TAO alone or in combination with cisplatin or paclitaxel in vitro and in vivo. Proliferation was assessed by WST-1 assay, and apoptosis was assessed by Annexin-V/PI FACS analysis in the CaSki cell line treated with a single agent or with the combinations of two agents. Expression of apoptosis-related proteins was analyzed by western blot analysis. A mouse xenograft model using CaSki cells was used to determine the in vivo activity of tetraarsenic oxide alone and in combination with cisplatin or paclitaxel by estimation of tumor size. At the end of the experiment, tumor tissue from each mouse was removed and processed for TUNEL analysis for confirmation of apoptotic cells. TAO was able to inhibit cell proliferation in a time- and dose-dependent manner. A combination of TAO and cisplatin effectively induced apoptosis by activating caspase-3. Using a mouse xenograft model, the sizes of tumors which were treated with a single agent and with a combination of agents decreased in a time-dependent manner. A combination of TAO and cisplatin resulted in a significantly reduced tumor size (P<0.05). The data for the histochemical staining of TUNEL-positive cells showed that the number of apoptotic cells was significantly increased by the combination of TAO and cisplatin. Thus, TAO is a good candidate for use in a combined regimen with cisplatin for patients with cervical cancer.",
Arsenic,1508597,"Sodium arsenite induces cyclooxygenase-2 expression in human uroepithelial cells through MAPK pathway activation and reactive oxygen species induction Abstract: Arsenic can induce reactive oxygen species (ROS) leading to oxidative stress and carcinogenesis. Bladder is one of the major target organs of arsenic, and cyclooxygenase-2 (COX-2) may play an important role in arsenic-induced bladder cancer. However, the mechanism by which arsenic induces COX-2 in bladder cells remains unclear. This study aimed at investigating arsenic-mediated intracellular redox status and signaling cascades leading to COX-2 induction in human uroepithelial cells (SV-HUC-1). SV-HUC-1 cells were exposed to sodium arsenite and COX-2 expression, mitogen-activated protein kinase (MAPK) phosphorylation, glutathione (GSH) levels, ROS induction and Nrf2 expression were quantified. Our results demonstrate that arsenite (1-10?M) elevates COX-2 expression, GSH levels, ROS and Nrf2 expression. Arsenite treatment for 24h stimulates phosphorylation of ERK and p38, but not JNK in SV-HUC-1 cells. Induction of Cox-2 mRNA levels by arsenite was attenuated by inhibitors of ERK, p38 and JNK. Arsenite-induced ROS generation and COX-2 expression were significantly attenuated by treatment with melatonin (a ROS scavenger), but enhanced by DL-buthionine-(S, R)-sulfoximine (BSO, an inhibitor of gamma-glutamylcysteine synthetase (?-GCS) resulting in lower GSH and increased ROS levels). These data indicate that arsenite promotes an induction of ROS, which results in an induction of COX-2 expression through activation of the MAPK pathway.",
Arsenic,1016357,"Influence of traditional agricultural practices on mobilization of arsenic from sediments to groundwater in Bengal delta Abstract: In the wake of the idea that surface derived dissolved organic carbon (DOC) plays an important role in the mobilization of arsenic (As) from sediments to groundwater and may provide a vital tool in understanding the mechanism of As contamination (mobilization/fixation) in Bengal delta; a study has been carried out. Agricultural fields that mainly cultivate rice (paddy fields) leave significantly large quantities of organic matter/organic carbon on the surface of Bengal delta which during monsoon starts decomposing and produces DOC. The DOC thus produced percolates down with rain water and mobilizes As from the sediments. Investigations on sediment samples collected from a paddy field clearly indicate that As coming on to the surface along with the irrigation water accumulates itself in the top few meters of sediment profile. The column experiments carried out on a 9 m deep sediment profile demonstrates that DOC has a strong potential to mobilize As from the paddy fields and the water recharging the aquifer through such agricultural fields contain As well above the WHO limit thus contaminating the shallow groundwater. Experiment also demonstrates that decay of organic matter induces reducing condition in the sediments. Progressively increasing reducing conditions not only prevent the adsorption of As on mineral surfaces but also cause mobilization of previously sorbed arsenic. There seems to be a cyclic pattern where As from deeper levels comes to the surface with irrigational water, accumulates itself in the sediments, and ultimately moves down to the shallow groundwater. The extensive and continual exploitation of intermediate/deep groundwater accelerates this cyclic process and helps in the movement of shallow contaminated groundwater to the deeper levels.",
Arsenic,1936145,"Utilization of anion exchange resin Spectra/Gel for separation of arsenic from water Abstract: Arsenic in drinking water is one of the most challenging health hazards facing mankind today. Arsenic is a naturally occurring carcinogen and creates epidemiological problems through chronic ingestion from drinking water. Arsenic is present in water primarily as As(III) or As(V). Removal of both As(III) and As(V) from water by adsorption on strong base anion-chloride has been studied. Arsenic concentration was measured by Inductively Coupled Argon Plasma (ICP) analysis. The resin was regenerated and the adsorbed arsenic fractions were eluted by using 2 M NaCl. The effect of different parameters that influence adsorption process, such as relative arsenic and resin concentrations, retention time, and pH, were investigated. Results obtained revealed that As(III) was poorly adsorbed, whereas As(V) was successfully retained on the resin. The adsorption process was optimized by using 1 g resin for 16 ppm As(V) at pH 9 for 30 min. The removal efficiency of As(V) was 99.2%.",
Arsenic,2149255,"Bioaccumulation of heavy metals by endemic Viola species from the soil in the vicinity of the As-Sb-Tl mine ""Allchar"", Republic of Macedonia Abstract: Allchar mine is an abandoned arsenic-antimony-thallium deposit located on the north-western part of Kouf Mt., Republic of Macedonia. Allchar is a unique deposit within the world, due to the variety of its mineral composition especially and in the high content of thallium. The aim of this work was to assess the level of contamination at this post-mining area as well as to determine the intensity of accumulation of various elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sr, Tl, V, and Zn) with focus on As, Sb and Tl, in two endemic Viola species from this locality (Viola allcharensis G. Beck, Viola arsenica G. Beck) and one Balkan endemic species (Viola macedonica Boiss. &amp; Heldr.). Samples of different plant parts and soil were digested and then analysed by ICP-AES. It was found that the accumulation of As, Sb, and Tl in these endemic species is significantly high. In this study a systematic investigation of the As-Sb-Tl contamination of soils and their bioavailability was carried out using the extraction procedure in order to explore the mobility and potential bioavailability of the As, Sb, and Tl.",
Arsenic,1509348,Chemical availability of arsenic and heavy metals in sediments from abandoned cinnabar mine tailings Abstract: ,
Arsenic,1255498,"Induction of anoikis by sodium arsenite in rat hepatoma FGC4 cells: Comparison with cadmium chloride and implications for assessment of regulation of heat shock protein 70 Abstract: Context: Arsenic, a toxic metal with major health concerns, elicits up-regulation of heat shock protein 70 (HSP70) in rat hepatoma FGC4 cells, together with evidence of detachment of viable cells from the growth substratum. Objective: To determine if this cell detachment was linked to anoikis, and the impact of this on measurement of HSP70 expression. Materials and Methods: FGC4 cells were exposed to sodium arsenite, and detached and attached cells were taken for assessment of cell viability, activation of pro-caspase 3, and expression of HSP70. Results: Exposure to sodium arsenite led to loss of viable cells from the substratum, associated with apoptosis in detached, but not attached, cells. Up-regulation of HSP70 of a similar magnitude was demonstrated in both cell populations. Exposure of cells to cadmium chloride, another toxic metal believed to act by an oxidative stress mechanism, produced very little release of viable cells from the culture substratum, was not associated with apoptosis, but did elicit a modest up-regulation of HSP70 in both cell populations. Discussion: Exposure of FGC4 cells to sodium arsenite elicits anoikis, a form of anchorage-dependent apoptosis, and assessment of the level of HSP70 up-regulation in such cells should take account of the detached cell population. Further, the data suggest that this phenomenon is selective to arsenic, rather than to another metal that shares a similar mechanism of toxicity.",
Arsenic,2278788,"Arsenic uptake by rice is influenced by microbe-mediated arsenic redox changes in the rhizosphere Abstract: Arsenic (As) uptake by rice is largely determined by As speciation, which is strongly influenced by microbial activities. However, little is known about interactions between root and rhizosphere microbes, particularly on arsenic oxidation and reduction. In this study, two rice cultivars with different radial oxygen loss (ROL) ability were used to investigate the impact of microbially mediated As redox changes in the rhizosphere on As uptake. Results showed that the cultivar with higher ROL (Yangdao) had lower As uptake than that with lower ROL (Nongken). The enhancement of the rhizospheric effect on the abundance of the arsenite (As(III)) oxidase gene (aroA-like) was greater than on the arsenate (As(V)) reductase gene (arsC), and As(V) respiratory reductase gene (arrA), resulting in As oxidation and sequestration in the rhizosphere, particularly for cultivar Yangdao. The community of As(III)-oxidizing bacteria in the rhizosphere was dominated by ?-Proteobacteria and ?-Proteobacteria and was influenced by rhizospheric effects, rice straw application, growth stage, and cultivar. Application of rice straw into the soil increased As release and accumulation into rice plants. These results highlighted that uptake of As by rice is influenced by microbial processes, especially As oxidation in the rhizosphere, and these processes are influenced by root ROL and organic matter application.",
Arsenic,2279435,"Modeling the emission, transport and deposition of contaminated dust from a mine tailing site Abstract: Mining operations are potential sources of airborne particulate metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, due to potential deleterious effects on human health and ecology. Dust emissions and dispersion of contaminants from the Iron King Mine tailings in Dewey-Humboldt, Arizona, a Superfund site, are currently being investigated through in situ field measurements and computational fluid dynamics modeling. These tailings are significantly contaminated with lead and arsenic with an average soil concentration of 1616 and 1420 ppm, respectively. Similar levels of these contaminants have also been measured in soil samples taken from the area surrounding the mine tailings. Using a computational fluid dynamics model, we have been able to model dust transport from the mine tailings to the surrounding region. The model includes a distributed Eulerian model to simulate fine aerosol transport and a Lagrangian approach to model fate and transport of larger particles. In order to improve the accuracy of the dust transport simulations both regional topographical features and local weather patterns have been incorporated into the model simulations.",
Arsenic,2278458,"Arsenic concentration variability, health risk assessment, and source identification using multivariate analysis in selected villages of public water system, Lahore, Pakistan Abstract: This paper reports high levels and variability in arsenic (As) levels at locations identified as one of the highest As-contaminated locations in Pakistan. Groundwater pollution related to arsenic has been reported since many years in the areas lying in outskirts of District Lahore, Pakistan. A comparative study is done to determine temporal variations of As from three villages, i.e., Kalalanwala (KLW), Manga Mandi (MM), and Shamki Bhattian (SKB). Seventy-three percent of the 30 investigated samples ranging in depth from 20 to 200 m, show an increasing trend in variations of As concentration over a time span of 4 years and 87% of samples exceeded the WHO standard of 10 ?g/L for As while 77% of samples have As concentration &gt;50 ?g/L (national standard). Further results indicate that high levels of As is accompanied with increase pH (r?=?0.8) favoring desorption of As from minerals at higher pH under oxidizing conditions. For health risk assessment of arsenic, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The residents of the studied areas had toxic risk index in the order of SKB&gt;KLW&gt;MM, with 87% of samples exceeding the typical toxic risk index 1.00 (ranging from 2.3-48.6) which was 83% (ranging from 0.3-41) 4 years before. The results of the present study therefore indicate that arsenic concentrations are increasing in the area, which needs an immediate attention to provide alternate sources of water to save people at risk.",
Arsenic,1034435,"Effect of heavy metals on cellular growth, metabolism and integrity of cultured Chinese hamster kidney cells Abstract: The effects of CdCl2, Na2CrO4, NaAsO2 and NiSO4 on cultured Chinese hamster kidney cells were studied over a concentration range for 48 h. Release of lactate dehydrogenase, a parameter of cell viability, was not closely related to cell proliferation except for Na2CrO4. A better correlation was obtained between glucose consumption and lactate production, and cellular growth. When studying toxic effects of metals in cell-culture systems, metabolic parameters should be determined in addition to cell viability and cellular growth. The results indicate that Chinese hamster kidney cells in culture might be useful to study mechanisms of metal-induced toxicity.",
Arsenic,1597426,Nuclear science and the story of a preserved leaf from a copy of the Great Bible Abstract: ,
Arsenic,1026157,"Multi-element screening by ICP-MS of two specimens of Napoleon's hair Abstract: Since 1960, it has been demonstrated by various analytical procedures that high concentrations of arsenic were present in Napoleon's hair. Various authors, indicating that the detected arsenic levels are a consequence of external contamination, have challenged the results of these examinations. In order to shed more light on this historical controversy, we have tested two samples of Napoleon's hair by inductively coupled plasma-mass spectrometry (ICP-MS). The samples of hair were decontaminated with acetone and were cut into small segments. For multi-element screening, hair samples were mineralized in concentrated nitric acid for 1 h at 70 degrees C, diluted 1:40 in specific solution with rhodium as an internal standard, and finally analyzed by ICP-MS on a Thermo Electron ICP/MS X7. Multi-element analysis of Napoleon's hair samples revealed massive amounts of arsenic (42.1 and 37.4 ng/mg), antimony (2.1 and 1.8 ng/mg) and elevated levels of mercury (3.3 and 4.7 ng/mg) and lead (229 and 112 ng/mg). In the case of arsenic, these concentrations, 40 times higher than the normal values, confirm the hypothesis of a significant exposure to arsenic. The concentrations of the other elements, in particular antimony and mercury, are in agreement with the data already known about the therapeutic treatments given to Napoleon, which were based on calomel (salt of mercury) and tartar emetic (antimony).",
Arsenic,1347487,WHOLE-BODY RETENTION AND EXCRETION OF [AS-74] ARSENIC ACID IN THE ADULT BEAGLE DOG Abstract: ,
Arsenic,1025511,"Toxicodynamics of subacute co-exposure to groundwater contaminant arsenic and analgesic-antipyretic drug acetaminophen in rats Abstract: Arsenic is an environmental contaminant, while acetaminophen is an extensively used nonsteroidal analgesic-antipyretic drug. We evaluated whether subacute co-exposure to arsenic and acetaminophen would produce more toxicity than that caused by exposure to either of the xenobiotics in rats. Toxicity was evaluated through changes in body weight, feed consumption, liver weight and microsomal drug-metabolizing enzymes, lipid peroxidation and antioxidants in liver. Arsenic had no effect on body weight and feed consumption. Acetaminophen-mediated decrease in body weight was attenuated in the co-exposed rats. Acetaminophen alone or its co-administration with arsenic decreased feed consumption. Arsenic reduced acetaminophen-mediated increase in the activities of drug-metabolizing enzymes. The co-exposure caused lesser lipid peroxidation than the individual exposure. Arsenic or acetaminophen given alone depleted GSH and decreased the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase and these effects remained mostly unaffected after co-exposure. The results suggest that co-exposure to arsenic and acetaminophen may be less hazardous than their independent exposure in rats.",
Arsenic,1032038,"Effects of phenylarsine oxide on agonist-induced hepatic vasoconstriction and glycogenolysis Abstract: A study was conducted to determine whether organic trivalent arsenicals exert effects on certain specific physiological and pathophysiological glycogenolytic/vasoconstrictive agonists in the perfused liver. The dose receptor relocations for phenylephrine stimulated glycogenolysis and vasoconstriction in the presence and absence of phenylarsine-oxide (637036) (PhAsO) were determined. At concentrations of phenylephrine which do not constrict the hepatic vasculature, PhAsO had very little effect on phenylephrine stimulated glycogenolysis. At concentrations of phenylephrine which increased portal vein pressure markedly, PhAsO inhibited completely the hepatic hemodynamic response to phenylephrine while inhibiting phenylephrine stimulated glycogenolysis by only 30 percent. Apparently PhAsO selectively inhibits the indirect effects of phenylephrine on mediation of vasoconstriction induced local ischemia. The effects of other hepatic agonists which likely exert their glycogenolytic effects either directly through interaction with parenchymal cells or indirectly through interaction with nonparenchymal cells were also studied. Studies were also performed of the ability of thiol compounds to reverse PhAsO inhibition of phenylephrine induced vasoconstriction and glycogenolysis. The author concludes that a major result of toxic arsenical exposure may be a diminished responsiveness of cells to various autacoid signals. Such cellular desensitization may participate in the development of the pathological lesions that characterize arsenical toxicosis.",
Arsenic,1023540,"Arsenic and mercury tolerance and cadmium sensitivity in Arabidopsis plants expressing bacterial gamma-glutamylcysteine synthetase Abstract: Cysteine sulfhydryl-rich peptide thiols are believed to play important roles in the detoxification of many heavy metals and metalloids such as arsenic, mercury, and cadmium in plants. The gamma-glutamylcysteine synthetase (gamma-ECS) catalyzes the synthesis of the dipeptidethiol gamma-glu-cys (gamma-EC), the first step in the biosynthesis of phytochelatins (PCs). Arabidopsis thaliana, engineered to express the bacterial gamma-ECS gene under control of a strong constitutive actin regulatory sequence (A2), expressed gamma-ECS at levels approaching 0.1% of total protein. In response to arsenic, mercury, and cadmium stresses, the levels of gamma-EC and its derivatives, glutathione (GSH) and PCs, were increased in the A2::ECS transgenic plants to three- to 20-fold higher concentrations than the increases that occurred in wild-type (WT). Compared to cadmium and mercury treatments, arsenic treatment most significantly increased levels of gamma-EC and PCs in both the A2::ECS transgenic and WT plants. The A2::ECS transgenic plants were highly resistant to arsenic and weakly resistant to mercury. Although exposure to cadmium produced three- to fivefold increases in levels of gamma-EC-related peptides in the A2::ECS lines, these plants were significantly more sensitive to Cd(II) than WT and trace levels of Cd(II) blocked resistance to arsenic and mercury. A few possible mechanisms for gamma-ECS-enhanced arsenic and mercury resistance and cadmium hypersensitivity are discussed.",
Arsenic,1029333,"Changes in hair arsenic levels in breast and bottle fed infants during the first year of infancy Abstract: Hair samples were collected from 13 breast fed and 19 bottle fed infants at one, three, six and twelve months of age. Food frequency data were also collected. Arsenic and antimony concentrations determined in washed hair samples by neutron activation procedures, rose significantly with age, the highest levels being evident at twelve months. Hair arsenic and antimony levels were independent of sex, and method of milk feeding. However, at twelve months, the median hair arsenic level for those infants receiving cereal at six months of age (0.655 microgram/g) was significantly higher (p = 0.05) than for those infants fed exclusively a milk based diet at this time (median = 0.225 microgram/g). Recent data show that cereals are major dietary sources of arsenic during infancy. Hence findings of this study suggest that changes in hair arsenic levels during infancy are related to the introduction of cereals in the diet.",
Arsenic,1032927,"Iodine deficiency disorders in the north-eastern region of Poland (Bia?ystok coordinating center) Abstract: This epidemiologic survey was carried out during the period between November 1992 and February 1993. Altogether 1431 children of age between 6 and 13 years from randomly selected 4 rural and 4 city schools were included into the study. The measurements of body height and weight, estimation of thyroid size by palpation and by USG were performed in every case. Urine was also sampled to measure iodine concentration with cerium-arsenic method. In 39.1% of the examined children goiter was found by physical examination and was more frequent in the rural group (41%) than in the urban children (36%). Mean iodine concentration in the urine was significantly higher in the group with goiter (52.7 micrograms/l) than in the group without goiter (42.3 micrograms/l) No symptoms of hypothyroidism were observed in the studied group. Moreover the presence of goiter had no influence on physical development of the children. According to the questionnaires, iodized salt is used by 26% of children in the cities and 16% in the villages. Neither iodine level in the urine nor prevalence of goiter was markedly affected by iodine prophylaxis. We conclude that the north-eastern region of Poland in an area of a moderate iodine deficiency and that the present model of iodine prophylaxis is insufficient.",
Arsenic,1519054,"A case-cohort study examining lifetime exposure to inorganic arsenic in drinking water and diabetes mellitus Abstract: BACKGROUND: Consumption of drinking water with high levels of inorganic arsenic (over 500?g/L) has been associated with type II diabetes mellitus (DM), but previous studies have been inconclusive about risks at lower levels (<100?g/L). We present a case-cohort study based on individual estimates of lifetime arsenic exposure to examine the relationship between chronic low-level arsenic exposure and risk of DM. METHODS: This case-cohort study included 141 cases of DM diagnosed between 1984 and 1998 as part of the prospective San Luis Valley Diabetes Study. A comparison sub-cohort of 488 participants was randomly sampled from 936 eligible participants who were disease free at baseline. Individual lifetime arsenic exposure estimates were determined using a methodology that incorporates the use of a structured interview to determine lifetime residence and employment history, geospatial modeling of arsenic concentrations in drinking water, and urine arsenic concentrations. A Cox proportional hazards model with known DM risk factors as time-dependent covariates was used to assess the association between lifetime exposure to inorganic arsenic in drinking water and incident DM. RESULTS: Our findings show a significant association between inorganic arsenic exposure and DM risk (hazard ratio [HR]=1.27, 95%=1.01, 1.59 per 15?g/L) while adjusting for ethnicity and time varying covariates age, body mass index and physical activity level. CONCLUSIONS: Exposure to low-level inorganic arsenic in drinking water is associated with increased risk for type II DM in this population based on a comprehensive lifetime exposure assessment.",
Arsenic,1024544,"Reaction mechanism underlying the in vitro transformation of thioarsenicals Abstract: Thioarsenicals have been paid much attention due to the toxicity of arsenic, since some of them are highly toxic and commonly found in the urine of mammals. We previously reported that thioarsenicals might be produced in red blood cells (RBCs). Here, we further characterized the mechanism underlying the production and metabolism of thioarsenicals in RBCs using 34S-labeled dimethylmonothioarsinic acid (34S-DMMTA(V)) and purified rat hemoglobin (Hb) or a rat RBC lysate. 34S-DMMTA(V) did not bind to Hb on incubation with purified rat Hb, remaining in its original form. However, when 34S-DMMTA(V) was incubated with a rat RBC lysate, only arsenic, i.e., not sulfur (34S), was detected in a form bound to Hb (As-Hb). In addition, another arsenic product containing sulfur (34S) in the molar ratio of 34S/As=2 was detected, which was assigned as dimethyldithioarsinic acid (DMDTA(V)), suggesting that arsenic does not bind to Hb in the form of 34S-DMMTA(V) but does so in the form of dimethylarsinous acid (DMA(III)). Namely, DMMTA(V) appeared to be hydrolyzed into dimethylarsinic acid (DMA(V)) and H34S-, and the released H34S- reacted with DMMTA(V) to produce DMDTA(V). Thus, DMMTA(V) was transformed into DMDTA(V) and DMA(V) (2DMMTA(V) -&gt;DMDTA(V)+DMA(V)), the latter product being reduced to DMA(III) in the presence of GSH and bound to Hb. In a separate experiment, (H34S-DMMTA(V) was incubated with sulfide (Na2S) and GSH. Although DMMTA(V) was not transformed into DMDTA(V) in the presence of only Na2S or GSH, it was transformed into DMDTA(V) in the presence of both Na2S and GSH. Our results suggest that DMMTA(V) is hydrolyzed enzymatically into DMA(V) and sulfide, the former being reduced to DMA(III) and bound to Hb, and the latter reacting with DMMTA(V) to yield DMDTA(V). Thus, DMMTA(V) is transformed into DMDTA(V) and DMA(V) through a hydrolytic reaction in a manner similar to a disproportionation reaction, DMA(V) being reduced and bound to Hb (As-Hb), and DMDTA(V) being produced more in the presence of sulfides in the medium.",
Arsenic,1519029,"Genotype-phenotype matching analysis of 38 Lactococcus lactis strains using random forest methods Abstract: BACKGROUND: Lactococcus lactis is used in dairy food fermentation and for the efficient production of industrially relevant enzymes. The genome content and different phenotypes have been determined for multiple L. lactis strains in order to understand intra-species genotype and phenotype diversity and annotate gene functions. In this study, we identified relations between gene presence and a collection of 207 phenotypes across 38 L. lactis strains of dairy and plant origin. Gene occurrence and phenotype data were used in an iterative gene selection procedure, based on the Random Forest algorithm, to identify genotype-phenotype relations. RESULTS: A total of 1388 gene-phenotype relations were found, of which some confirmed known gene-phenotype relations, such as the importance of arabinose utilization genes only for strains of plant origin. We also identified a gene cluster related to growth on melibiose, a plant disaccharide; this cluster is present only in melibiose-positive strains and can be used as a genetic marker in trait improvement. Additionally, several novel gene-phenotype relations were uncovered, for instance, genes related to arsenite resistance or arginine metabolism. CONCLUSIONS: Our results indicate that genotype-phenotype matching by integrating large data sets provides the possibility to identify gene-phenotype relations, possibly improve gene function annotation and identified relations can be used for screening bacterial culture collections for desired phenotypes. In addition to all gene-phenotype relations, we also provide coherent phenotype data for 38 Lactococcus strains assessed in 207 different phenotyping experiments, which to our knowledge is the largest to date for the Lactococcus lactis species.",
Arsenic,1597403,Removal of Arsenic(III) from Drinking Water by Adsorption with Titanium and Ferrous Oxide Nanoparticles Abstract: ,
Arsenic,2149148,"A case of bismuth intoxication with irreversible renal damage Abstract: Bismuth is a chemical element symbolized as Bi and is a trivalent poor metal, which chemically resembles arsenic and antimony. Colloidal bismuth subcitrate (CBS) and bismuth subsalicylate are the bismuth salts widely used in the treatment of peptic ulcers, functional dyspepsia, and chronic gastritis. Intoxications with CBS are rare. In a few case reports, acute renal failure was described, but the literature review revealed no chronic renal failure related to CBS intoxication. In this case report we present a 21-year old female with chronic renal failure after a one year follow-up of CBS intoxication.",
Arsenic,1597408,"Synthesis of tetra-substituted calix[4]arene ionophores and their recognition studies toward toxic arsenate anions Abstract: The article displays the synthesis of a family of novel tetra-substituted calix[4]arene ionophores bearing furyl, phenyl, and pyridyl units in the cone conformation. In the synthesis, the lower rims of calix[4]arene scaffold were modified in order to establish the influence of the molecular structure of calixarene on recognition of toxic anions as arsenate by liquid-liquid extraction process. In addition, the effects of solvent, solution conditions (mainly pH), and counter ions (Cl-, NO3-, and SO42-) on the extraction abilities of the ionophores were studied. From the liquid-liquid phase extraction studies, it was observed that the structures of the tetra-substituted calix[4]arenes influenced the extraction percentage of selected toxic anion. Also, thermodynamic parameters, such as the free energy (Delta G degrees) and enthalpy (Delta H degrees) indicated an exothermic nature of extraction and a spontaneous and favorable process.",
Arsenic,8606,"In vivo studies in male mice on the mutagenic effects of inorganic arsenic Abstract: The ability of sodium meta-arsenite (NaAsO2) to produce genetic damage in vivo has been evaluated in mice by the micronucleus test on bone marrow cells and the dominant lethality and sperm abnormality assays on male germ cells. The dose-related linear increase of micronuclei observed in somatic cells together with the negative results obtained in reproductive cells suggest that NaAsO2, under the conditions of the present experiments, displays clastogenic properties in vivo in laboratory animals, but is unable to produce heritable damage.",
Arsenic,627548,"Genotoxic effects in human lymphocytes exposed to arsenic and vitamin A Abstract: Arsenic is a ubiquitous trace element and a well-established human carcinogen. In search for an 'antidote' to this global poison, this work was undertaken to study the probable beneficial effect of vitamin A upon arsenic induced genotoxicity. Peripheral blood lymphocyte culture was carried out to study the effects of arsenic at three different dose levels (0.5, 1 and 2 microg) for 24 h prior to harvesting. In addition, mutagenic in vitro effect of ethyl methanesulphonate was studied as a positive control. Genotoxic variables presented here are sister chromatid exchanges (SCE), cell cycle proliferative index/replicative index (CCPI/RI), average generation time (AGT) and population doubling time (PDT). Inevitably, arsenic treatment showed dose-dependent augmentation in the incidences of SCE and CCPI/RI together with AGT and PDT. However, vitamin A supplemented arsenic cultures demonstrated remarkable resurgence in the described genotoxic parameters. This data shows that vitamin A might be a useful interventional treatment in arsenic poisoning.",
Arsenic,2088561,"Arsenic scavenging by aluminum-substituted ferrihydrites in a circumneutral pH river impacted by acid mine drainage Abstract: Ferrihydrite (Fh) is a nanocrystalline ferric oxyhydroxide involved in the retention of pollutants in natural systems and in water-treatment processes. The status and properties of major chemical impurities in natural Fh is however still scarcely documented. Here we investigated the structure of aluminum-rich Fh, and their role in arsenic scavenging in river-bed sediments from a circumneutral river (pH 6-7) impacted by an arsenic-rich acid mine drainage (AMD). Extended X-ray absorption fine structure (EXAFS) spectroscopy at the Fe K-edge shows that Fh is the predominant mineral phase forming after neutralization of the AMD, in association with minor amount of schwertmannite transported from the AMD. TEM-EDXS elemental mapping and SEM-EDXS analyses combined with EXAFS analysis indicates that Al(3+) substitutes for Fe(3+) ions into the Fh structure in the natural sediment samples, with local aluminum concentration within the 25-30 ± 10 mol %Al range. Synthetic aluminous Fh prepared in the present study are found to be less Al-substituted (14-20 ± 5 mol %Al). Finally, EXAFS analysis at the arsenic K-edge indicates that As(V) form similar inner-sphere surface complexes on the natural and synthetic Al-substituted Fh studied. Our results provide direct evidence for the scavenging of arsenic by natural Al-Fh, which emphasize the possible implication of such material for scavenging pollutants in natural or engineered systems.",
Arsenic,711001,"Oxidative modifications of proteins by sodium arsenite in human umbilical vein endothelial cells Abstract: Epidemiologic studies have demonstrated that chronic arsenic exposure is associated with the incidence of chronic diseases. This association is partly related to the increase in reactive oxygen species (ROS) overload and protein oxidation that result from arsenic exposure. In this study, we intended to identify proteins susceptible to oxidative carbonylation by sodium arsenite and the impact of carbonylation on the function of these proteins in human umbilical vein endothelial cells (HUVECs). The 2,4-dinitrophenylhydrazine (DNPH) dot-blot assay revealed that arsenite (0-50 muM) dose-dependently increased protein carbonylation. Consistent with these findings, the cellular ROS level as measured by 2',7'-dichlorofluorescein diacetate (DCHF-DA) assay was increased in cells exposed to arsenite. By two-dimensional gel electrophoresis and matrix assist laser desorption ionization time of flight mass spectrometry (MALDI-TOF/MS), one glycolytic enzyme, enolase-alpha, two cytoskeleton proteins, fascin (F-actin associated protein) and vimentin, and two protein quality control proteins, HSC70 (heat-shock cognate protein 70), and PDIA3 (protein disulfide isomerase family A, member 3) were identified to be arsenic-sensitive carbonlyated proteins. Accompanied by carbonylation, enolase-alpha activity was dose-dependently decreased and the F-actin filament network was disturbed. Taken together, our results suggest that arsenite exposure results in the generation of carbonylated proteins, and the resultant changes in energy metabolism and in the cytoskeletal network may partly lead to cell damage. (c) 2010 Wiley Periodicals, Inc. Environ Toxicol, 2010.",
Arsenic,1380188,"Acute arsenic toxication of a free-ranging white-tailed deer in New York Abstract: An adult, female white-tailed deer (Odocoileus virginianus) died due to acute arsenic intoxication in an intensively managed northern hardwood forest in northern New York. We hypothesize that the deer licked trees injected with Silvisar 550, which contains monosodium methanearsonate. We believe this is the first report of death of a free-ranging white-tailed deer, due to ingestion of monosodium methanearsonate.",
Arsenic,1023538,"Arsenite regulates Cystic Fibrosis Transmembrane Conductance Regulator and P-glycoprotein: evidence of pathway independence Abstract: In the past, people have argued for and against the theory of reciprocal regulation of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and P-glycoprotein (Pgp). Data have indicated that this may occur in vitro during drug-induced selection of cells, and in vivo during development. Much of this debate has been caused by a severe lack of mechanistic details involved in such regulation. Our past data indicate that certain Pgp modulators can affect CFTR expression and function. The goal of this study was to investigate the effects of trivalent arsenic (arsenite), a known transcriptional activator of Pgp, on CFTR expression. In vitro analyses in T-84 cells that express basal levels of Pgp and CFTR were conducted using a variety of molecular techniques. Expressions of both genes were altered following treatment with arsenite in a dose- and time-dependent fashion. CFTR expression was suppressed almost three-fold by arsenite, along with a concomitant increase in P-glycoprotein expression. We also report that a member of the MAPK-family, the ERK-mediated signaling cascade is implicated in suppression of CFTR expression following treatment with arsenite. However, this particular pathway is not involved in regulation of P-glycoprotein expression in T-84 cells following treatment with arsenite. Thus, the regulatory pathways that control functional expression of CFTR and P-glycoprotein following arsenite treatment in T-84 cells are distinct and independent.",
Arsenic,1508719,"The effect of cooking and washing rice on the bio-accessibility of As, Cu, Fe, V and Zn using an on-line continuous leaching method Abstract: A previously developed method based on continuous on-line leaching with artificial gastro-intestinal fluids was used to determine the bio-accessible fraction of As, Cu, Fe, V and Zn in brown and white rice from California by inductively coupled mass spectrometry (ICP-MS). Saliva generally accounted for the largest percentage of total element leached in comparison to gastric and intestinal juices. Arsenic speciation analysis was performed on the saliva and gastric juice leachates using ion exchange chromatography coupled to ICP-MS. The four most toxic species of As (As(III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and As(V)), as well as Cl(-) in the gastric juice leachate, were successfully separated within 5.5min using a simple nitric acid gradient. While cooking rice had relatively little effect on total bio-accessibility, a change in species from As(V) and DMA to As(III) was observed for both types of rice. On the other hand, washing the rice with doubly deionized water prior to cooking removed a large percentage of the total bio-accessible fraction of As, Cu, Fe, V and Zn.",
Arsenic,1346119,"DNA damaging agents increase gadd153 (CHOP-10) messenger RNA levels in bovine preimplantation embryos cultured in vitro Abstract: DNA damage and other forms of stress are believed to be important factors in reducing the efficiency of in vitro embryo transfer techniques in farm animals. The expression of mRNAs from stress-responsive genes such as gadd153 (CHOP-10, ddit3) may provide a means of assessing the quality of embryos produced in vitro. Treatment of bovine granulosa cell cultures with the DNA-damaging agents, methyl methane-sulphonate (MMS) or sodium arsenite, induced the expression of an mRNA, which hybridized with the hamster gadd153 cDNA. Part of the corresponding bovine cDNA was amplified by nested polymerase chain reaction (PCR), cloned, and sequenced. Using a sensitive reverse transcriptase-PCR assay we have investigated the expression of gadd153 and beta-actin in blastocyst-stage bovine embryos treated with MMS or sodium arsenite. Both agents produced an increase in the ratio of gadd153 mRNA relative to beta-actin. These results show that there are changes in gene expression in blastocyst-stage bovine embryos in response to genotoxic stress, suggesting that an increase in gadd153 mRNA is a useful marker of DNA damage and metabolic stress in preimplantation embryos.",
Arsenic,2298728,"Folate and Cobalamin Modify Associations between S-adenosylmethionine and Methylated Arsenic Metabolites in Arsenic-Exposed Bangladeshi Adults Abstract: Chronic exposure to inorganic arsenic (InAs) through drinking water is a major problem worldwide. InAs undergoes hepatic methylation to form mono- and dimethyl arsenical species (MMA and DMA, respectively), facilitating arsenic elimination. Both reactions are catalyzed by arsenic (+3 oxidation state) methyltransferase (AS3MT) using S-adenosylmethionine (SAM) as the methyl donor, yielding the methylated product and S-adenosylhomocysteine (SAH), a potent product-inhibitor of AS3MT. SAM biosynthesis depends on folate- and cobalamin-dependent one-carbon metabolism. With the use of samples from 353 participants in the Folate and Oxidative Stress Study, our objective was to test the hypotheses that blood SAM and SAH concentrations are associated with arsenic methylation and that these associations differ by folate and cobalamin nutritional status. Blood SAM and SAH were measured by HPLC. Arsenic metabolites in blood and urine were measured by HPLC coupled to dynamic reaction cell inductively coupled plasma MS. In linear regression analyses, SAH was not associated with any of the arsenic metabolites. However, log(SAM) was negatively associated with log(% urinary InAs) (regression coefficient ?: -0.11; 95% CI: -0.19, -0.02; P = 0.01), and folate and cobalamin nutritional status significantly modified associations between SAM and percentage of blood MMA (%bMMA) and percentage of blood DMA (%bDMA) (P = 0.02 and P = 0.01, respectively). In folate- and cobalamin-deficient individuals, log(SAM) was positively associated with %bMMA (6.96; 95% CI: 1.86, 12.05; P &lt; 0.01) and negatively associated with %bDMA (-6.19; 95% CI: -12.71, 0.32; P = 0.06). These findings suggest that when exposure to InAs is high, and methyl groups are limiting, SAM is used primarily for MMA synthesis rather than for DMA synthesis, contributing additional evidence that nutritional status may explain some of the interindividual differences in arsenic metabolism and, consequently, susceptibility to arsenic toxicity.",
Arsenic,2215715,"Treatment outcomes in relapsed acute promyelocytic leukemia patients initially treated with all-trans retinoic acid and arsenic compound-based combined therapies Abstract: Contemporary combined therapies that include the use of all-trans retinoic acid (ATRA) and arsenic compounds have reduced relapse rates from ~50 to &lt;10% in acute promyelocytic leukemia (APL) patients, however relapse treatment remains controversial. Treatment outcomes in relapsed patients with APL previously treated with combined ATRA + arsenic compound therapy were investigated. A retrospective, observational study was conducted of 25 patients with APL (male to female ratio, 17:8; mean age, 36.4±10.3 years) exhibiting first-time relapse following combined ATRA + arsenic compound therapy. These patients were subsequently treated with secondary ATRA + arsenic compound therapy, salvage chemotherapy, monoclonal antibody therapy or intrathecal chemotherapy, between January 1994 and December 2010. The overall remission rate, duration of remission and toxic effects were assessed. Patient outcomes included mortality during secondary induction therapy (6/25, 24.0%); complete recovery from central nervous system (CNS) relapse following intrathecal chemotherapy (1/25, 4.0%); complete remission following ATRA + arsenic compound therapy (10/25, 40.0%), chemotherapy (3/25, 12.0%) and targeted therapy (1/25, 4.0%); and non-remission (NR) following ATRA + arsenic compound therapy (4/25, 16%). Four (16.0%) patients were subsequently treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT), two of which remained disease-free at the end of the study period and two of which succumbed to the disease. Secondary bone marrow and CNS relapse occurred in 14 (56.0%) patients and one (4.0%) patient, respectively. ATRA + arsenic compound-based combination therapy was effective in re-inducing morphological remission in relapsed patients with APL with previous exposure to ATRA + arsenic compounds, producing low molecular remission rates and high risk of secondary relapse. Furthermore, investigation of early allo-HSCT is required to determine its potential as a therapeutic option for re-inducing morphological remission in relapsed patients with APL with previous exposure to ATRA + arsenic compounds.",
Arsenic,2298675,"Exploring the potential of metallic nanoparticles within synthetic biology Abstract: The fields of metallic nanoparticle study and synthetic biology have a great deal to offer one another. Metallic nanoparticles as a class of material have many useful properties. Their small size allows for more points of contact than would be the case with a similar bulk compound, making nanoparticles excellent candidates for catalysts or for when increased levels of binding are required. Some nanoparticles have unique optical qualities, making them well suited as sensors, while others display para-magnetism, useful in medical imaging, especially by Magnetic Resonance Imaging (MRI). Many of these metallic nanoparticles could be used in creating tools for synthetic biology, and conversely the use of synthetic biology could itself be utilised to create nanoparticle tools. Examples given here include the potential use of quantum dots (QDs) and gold nanoparticles as sensing mechanisms in synthetic biology, as well as ways of using synthetic biology to create ways of sensing metal nanoparticles based on current methods of detecting metals and metalloids such as arsenate. There are a number of organisms which are able to produce a range of metallic nanoparticles naturally, such as species of the fungus Phoma which produces anti-microbial silver nanoparticles. The Biological synthesis of nanoparticles may have many advantages over their more traditional industrial synthesis. If the proteins involved in biological nanoparticle synthesis can be put into a suitable bacterial chassis then they might be manipulated and the pathways engineered in order to produce more valuable nanoparticles.",
Arsenic,134331,"A hospital-based case-control study of stillbirths and environmental exposure to arsenic using an atmospheric dispersion model linked to a geographical information system Abstract: Although adverse reproductive outcomes have been associated with arsenic exposure, the extent and severity of the effects of chronic inhalation of low levels of arsenic on reproduction are not known. We conducted a hospital-based case-control study of stillbirths in a central Texas community that included a facility with more than a 60-year history of producing primarily arsenic-based agricultural products. We collected data on 119 cases and 267 controls randomly selected from healthy live-births at the same hospital and matched for year of birth. We abstracted medical and demographic data for the period January 1, 1983, to December 31, 1993, from hospital records and estimated socioeconomic status by median income from the 1990 Population and Housing Census data. We estimated arsenic exposure levels from airborne emission estimates and an atmospheric dispersion model and linked the results to a geographical information system (GIS) database. Exposure was linked by GIS to residential address at time of delivery. A conditional logistic regression model was fitted including maternal age, race/ethnicity, parity, income group, exposure as a categorical variable, and exposure-race/ethnicity interaction. The prevalence odds ratio observed for Hispanics in the high-exposure group (>100 ng per m3 arsenic) was 8.4, with a 95% confidence interval of 1.4-50.1.",
Arsenic,1025813,"Metallothionein responses in the Asiatic clam (Corbicula fluminea) after exposure to trivalent arsenic Abstract: The main objective of this work was to evaluate arsenic effects on metallothionein (MT) induction by exposing a freshwater Asiatic clam (Corbicula fluminea) to different concentrations of this metalloid. The presence of MT-like proteins was detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis and compared with a standard rabbit MT. In addition, the polarographic response showed good correspondence between standard MT and MT-like curves from C. fluminea, allowing MT quantification. The results show that clams exposed to different concentrations of arsenic are able to induce significant levels of MTs. Although variability was found in MT induction, significant differences in MT levels were found after 28 days of exposure in all treatments in comparison with the controls, suggesting that exposure to arsenic induced MT-like proteins in C. fluminea.",
Arsenic,2064288,"Trait-directed de novo population transcriptome dissects genetic regulation of a balanced polymorphism in phosphorus nutrition/arsenate tolerance in a wild grass, Holcus lanatus Abstract: The aim of this study was to characterize the transcriptome of a balanced polymorphism, under the regulation of a single gene, for phosphate fertilizer responsiveness/arsenate tolerance in wild grass Holcus lanatus genotypes screened from the same habitat. De novo transcriptome sequencing, RNAseq (RNA sequencing) and single nucleotide polymorphism (SNP) calling were conducted on RNA extracted from H. lanatus. Roche 454 sequencing data were assembled into c. 22 000 isotigs, and paired-end Illumina reads for phosphorus-starved (P-) and phosphorus-treated (P+) genovars of tolerant (T) and nontolerant (N) phenotypes were mapped to this reference transcriptome. Heatmaps of the gene expression data showed strong clustering of each P+/P- treated genovar, as well as clustering by N/T phenotype. Statistical analysis identified 87 isotigs to be significantly differentially expressed between N and T phenotypes and 258 between P+ and P- treated plants. SNPs and transcript expression that systematically differed between N and T phenotypes had regulatory function, namely proteases, kinases and ribonuclear RNA-binding protein and transposable elements. A single gene for arsenate tolerance led to distinct phenotype transcriptomes and SNP profiles, with large differences in upstream post-translational and post-transcriptional regulatory genes rather than in genes directly involved in P nutrition transport and metabolism per se.",
Arsenic,1337747,"Effect of glucosamine and chitooligomer on the toxicity of arsenite against Escherichia coli Abstract: Escherichia coli was selected as the sample to study the toxicity of arsenite in the presence of saccharides. The effect of glucosamine, N-acetylglucosamine, glucose, lactose, sucrose, glucosamine and cyclodextrin on the toxicity of arsenite against E. coli was investigated by microcalorimetry. The glucosamine and the tested chitooligomer decreased the toxicity of arsenite on cells of E. coli, and the effect of glucosamine was stronger than that of the chitooligomer. These results suggest that the glucosamine and chitooligomer may be employed as the assistant antidote for arsenite.",
Arsenic,1357782,"Art Hazards. An Overview for Sanitarians and Hygienists Abstract: Art hazards are discussed. A large number of potential health and safety hazards may confront the modern artist. Although such craftsmen are knowledgeable about their art forms, they are often uninformed about the potential adverse health effects that can result from their work. They usually have no background in the sciences, particularly chemistry. Specific hazards associated with painting, printmaking, photography, ceramics, and sculpturing are discussed. The major dangers associated with painting are from toxic pigments that can contain heavy metals, such as lead (7439921), arsenic (7440382), chromium (7440473) or mercury (7439976), and solvents. Hazards associated with printmaking include exposure to solvent vapors in silk screening, corrosive chemicals in plate etching, and dust inhalation in lithography. Photographic developers are responsible for many of the common complaints of photographers. These can irritate the skin, eyes, and respiratory tract. Many are sensitizers, but others produce systemic effects if inhaled or ingested. Ceramic artists can be exposed to many hazardous materials, generally related to dry clays, glazes, or kiln use. Ingestion and inhalation are important routes of exposure for ceramicists. Sculptors are exposed to a variety of hazards, such as metal fumes in welding of steel structures, sensitizing epoxy resins in plastic sculptors, and dust, solvent, and preservatives in wood sculpturing. Recommended control measures for preventing exposure to health and safety hazards in the arts are listed.",
Arsenic,1024747,"Homeopathic remedy for arsenic toxicity?: Evidence-based findings from a randomized placebo-controlled double blind human trial Abstract: Millions of people are at risk of groundwater arsenic contamination, but supply of arsenic-free drinking water is grossly inadequate. The present study was intended to examine if a potentized homeopathic remedy reportedly showing ameliorating potentials in people inhabiting high-risk arsenic-contaminated areas but drinking arsenic-free water, can also ameliorate arsenic toxicity in subjects living in high-risk arsenic-contaminated areas, and drinking arsenic-contaminated water. This pilot study was conducted on 20 males and 19 females of village Dasdiya (arsenic contaminated) who initially agreed to act as volunteers; but as many as 14, mostly placebo-fed subjects, later dropped out. 18 volunteers, 14 males and 4 females, from a distant village, Padumbasan (arsenic-free), served as negative controls. In a double blind placebo-controlled study, a potentized remedy of homeopathic Arsenicum Album-30 and its placebo (Succussed Alcohol-30) were given randomly to volunteers. Arsenic contents in urine and blood and several widely accepted toxicity biomarkers and pathological parameters in blood were analyzed before and after 2 months of administration of either verum or placebo. Elevated levels of ESR, creatinine and eosinophils and increased activities of AST, ALT, LPO and GGT were recorded in arsenic exposed subjects. Decreased levels of hemoglobin, PCV, neutrophil percentages, and GSH content and low G-6-PD activity were also observed in the arsenic exposed people. The administration of verum appeared to make positive modulations of these parameters, suggestive of its ameliorative potentials. Most of the subjects reported better appetite and improvement in general health, thereby indicating possibility of its use in remote arsenic-contaminated areas as an interim health support measure to a large population at risk.",
Arsenic,627874,"Toxicity of a trivalent organic arsenic compound, dimethylarsinous glutathione in a rat liver cell line (TRl 1215) Abstract: BACKGROUND AND PURPOSE: Although inorganic arsenite (As(III)) is toxic in humans, it has recently emerged as an effective chemotherapeutic agent for acute promyelocytic leukemia (APL). In humans and most animals, As(III) is enzymatically methylated in the liver to weakly toxic dimethylarsinic acid (DMAs(V)) that is a major pentavalent methylarsenic metabolite. Recent reports have indicated that trivalent methylarsenicals are produced through methylation of As(III) and participate in arsenic poisoning. Trivalent methylarsenicals may be generated as arsenical-glutathione conjugates, such as dimethylarsinous glutathione (DMAs(III)G), during the methylation process. However, less information is available on the cytotoxicity of DMAs(III)G. EXPERIMENTAL APPROACH: We synthesized and purified DMAs(III)G using high performance TLC (HPTLC) methods and measured its cytotoxicity in rat liver cell line (TRL 1215 cells). KEY RESULTS: DMAs(III)G was highly cytotoxic in TRL 1215 cells with a LC(50) of 160 nM. We also found that DMAs(III)G molecule itself was not transported efficiently into the cells and was not cytotoxic; however it readily became strongly cytotoxic by dissociating into trivalent dimethylarsenicals and glutathione (GSH). The addition of GSH in micromolar physiological concentrations prevented the breakdown of DMAs(III)G, and the DMAs(III)G-induced cytotoxicity. Physiological concentrations of normal human serum (HS), human serum albumin (HSA), and human red blood cells (HRBC) also reduced both the cytotoxicity and cellular arsenic uptake induced by exposure to DMAs(III)G. CONCLUSIONS AND IMPLICATIONS: These findings suggest that the significant cytotoxicity induced by DMAs(III)G may not be seen in healthy humans, even if DMAs(III)G is formed in the body from As(III).",
Arsenic,1017607,"Factors impacting on the excess arseniasis prevalence due to indoor combustion of high arsenic coal in a hyperendemic village Abstract: <strong>BACKGROUND: </strong>A few villages in Southwest Guizhou, China represented a unique case of arseniasis due to indoor combustion of high arsenic-content coal. The present study is aimed to analyze the contribution of possible factors or of their combination to excess prevalence of arseniasis in the exposed population.<br /><br /><strong>METHODS: </strong>An epidemiological investigation was conducted in all the members of three large ethnic, patrilineal clans in one of the hyperendemic villages (702 residents in 178 families, including 408 Han and 294 Hmong) where farmers of different ethnic origin have been living together in the same village for generations. A multilevel model logistic regression analysis was performed.<br /><br /><strong>RESULTS: </strong>The arseniasis prevalence was found to associate with the duration of As indoor exposure (years of high As coal burning and of poorly ventilated traditional stove using) and is largely dependent on the subject's ethnicity and clan consanguinity, too. The prevalence of arseniasis in ethnic Han residents was significantly higher than that in their Hmong neighbors (35.0 vs 4.8% OR = 15.18, 95% CI = 3.45-67.35). Notable variances of arseniasis prevalence were observed not only between the ethnic Han clans (G1, G3, and B) and Hmong clan P, but also between different lineages (G1 and G2) inside the ethnic Han clan. Smokers suffered more frequently from arseniasis than non-smokers (47.3 vs 15.7% OR = 5.42, 95% CI = 2.25-12.93).<br /><br /><strong>CONCLUSIONS: </strong>Arseniasis prevalence in this unique exposure case was impacted by an array of multiple factors. Besides a long-term indoor exposure to As, the ethnicity or the clan consanguinity of exposed subjects may play an important role, too.",
Arsenic,1794773,"Arsenate content, and arsenate/phosphate and arsenate/sulphate competitive adsorption in soils from Minas Gerais, Brazil Abstract: The high toxicity of arsenic to humans and animals creates the need to study the chemical behavior of arsenate in soils that can help in the mitigation of areas contaminated with arsenic. This work aimed to evaluate the total content and adsorption in the absence and presence of phosphate and sulfate anions in six different soil classes in the state of Minas Gerais, Brazil. Soils aim of this study are: Fluvic Neosol (RU), Haplic Gleysol (GX), Melanic Gleysol (GM) and Typical Distrophic Red Latosol (LVd) collected in Lavras, MG; Quartzenic Neosol (RQ) collected in Itutinga, MG, and Typical Distrophic Yellow Latosol (Lad) collected in Rosário, MG. Soil samples were dried, ground and sieved through a sieve of 2mm for the test run of adsorption and sieved through a sieve with a mesh of plastic 1.5mm for the As determination. The As content was determined by the method 3051A. The rate 1500µmolL-1As, 1500µmol L-1 As + 1500µmol L-1 P, 1500µmol L-1 As + 750µmol L-1 As were used to evaluate As adsorption, soil solution rate of 1:100, pH 5,5 and ionic force of 15mmol.L-1. The mean As content in the six soils was between 0,14 and 9,3mgkg-1. The adsorpted percentage of As in absence of other anions followed the sequence GM>LVd=RU=LAd=GX=RQ. Phosphate and sulphate addition reduced the percentage of adsorpted arsenic, consequently there was an increase of disponible arsenic in the soil solution.",
Arsenic,1519014,"Evaluation of status of arsenic, cadmium, lead and zinc levels in biological samples of normal and arthritis patients of age groups (46 - 60) and (61 - 75) years Abstract: <strong>BACKGROUND: </strong>Arthritis is a chronic inflammatory disease resulting in inflammation of diarthrodial joints (particularly joints of hands, wrists, feet, knees, ankles, and shoulders), manifested by swelling and functional impairment. This study was designed to evaluate the levels of the toxic elements arsenic (As), cadmium (Cd), and lead (Pb) and correlate those with the essential trace element zinc (Zn) in biological samples (scalp hair, blood, and urine) of arthritis patients, in two age groups (46 - 60 and 61 - 75) of both genders. For comparison purposes all three biological samples were collected from gender- and age-matched non-arthritic subjects as referents.<br /><br /><strong>METHODS: </strong>The As, Cd, and Pb in biological samples were analysed by electrothermal atomic absorption spectrometry, prior to microwave assisted acid digestion. The level of Zn was determined by flame atomic absorption spectrometry. The validity and accuracy of the methodology was checked by using Certified Reference Materials (CRM) from the Community Bureau of Reference (BCR) of the Commission of the European Community and with those values obtained by conventional wet acid digestion method on the same CRMs.<br /><br /><strong>RESULTS: </strong>The results of this study showed that the mean values of As, Cd, and Pb were higher in blood, scalp hair, and urine samples of arthritis patients as compared to those values obtained in age-matched referent subjects. The concentration of Zn was lower in the biological samples of rheumatoid arthritis patients of both genders with respect to non-arthritic subjects. The urinary levels of the elements studied were found to be higher in the arthritis patients than in the age-matched healthy referents (p < 0.001).<br /><br /><strong>CONCLUSIONS: </strong>An inverse correlation was observed between Zn and toxic elements in biological samples of arthritis patients (r = 0.612 - 0.754). Intake of certain antioxidant micronutrients, particularly a zinc supplement, may protect against the development of rheumatoid arthritis.",
Arsenic,1021785,"Assessment of daily intake of toxic elements due to consumption of vegetables, fruits, meat, and seafood by inhabitants of Xiamen, China Abstract: This study was designed to estimate the dietary intake of cadmium (Cd), lead (Pb), mercury (Hg) (total and methyl), and arsenic (As) by inhabitants of Xiamen, China. The concentrations of these toxic elements (TEs) were determined in vegetables, fruits, meat, and seafood samples randomly acquired in 5 districts of Xiamen between 2005 and 2009. Health risks were evaluated for inhabitants of Xiamen due to dietary consumption. The target hazard quotient (THQ) values for individual elements were far below 1, indicating minimal noncarcinogenic risks from TEs for inhabitants of Xiamen under the current food consumption rate. However, consumption of the entire foodstuffs could lead to potential health risks since the 95th percentile HI was higher than 1. The relative contributions of Cd, Pb, Hg T, and As to the HI were 16.0%, 15.9%, 5.9%, and 62.2% for the mean exposure level, and 13.3%, 13.4%, 5.6%, and 67.9% for the 95th percentile estimate. The THQ value of methyl mercury through consumption of cephalopod was less than 1. Tomato, cephalopod, eggplant, cabbage, orange, and pork were the main sources of total dietary intakes of TEs. The estimation of carcinogenic risk shows that the carcinogenic rate of arsenic exceeded the accepted risk level of 10(-4) . Therefore, the carcinogenic risk of arsenic for inhabitants of Xiamen is of concern. Practical Application:? Tomato, cephalopod, eggplant, cabbage, orange, and pork were the main sources of dietary intakes of TEs in Xiamen, China. The carcinogenic risk of arsenic for inhabitants in this area who consume large amounts of fruits and vegetables daily may be of concern. Consumers are encouraged to eat fruits and vegetables with different origins and eat less cephalopod to reduce the possibilities of continuously eating commodities from the contaminated areas.",
Arsenic,1704126,"Interactive influence of arsenate and selenate on growth and nitrogen metabolism in wheat (Triticum aestivum L.) seedlings Abstract: The effect of arsenate and selenate, either alone or in combination, on plant growth and nitrogen metabolism was studied in wheat seedlings. The root-shoot elongation and the biomass production were significantly decreased with increasing arsenate concentrations. Arsenate toxicity severely affected activities of different antioxidant scavenging enzymes and oxidative stress markers in the test seedlings. The activities of nitrate and nitrite reductase were also affected resulting in reduced nitrate and nitrite contents. Glutamine synthetase and glutamate synthase activities were also reduced, whereas the glutamate dehydrogenase activity was substantially increased resulting in an increased accumulation of ammonium contents in the test seedlings. Arsenate treatments also adversely affected the levels of total and soluble nitrogen contents and free amino acid contents. Combined application of arsenate with selenate in the test seedlings showed significant alterations in all parameters tested under the purview of arsenate treatment alone leading to better growth and nitrogen metabolism.",
Arsenic,1022910,"Transcription factor Nrf2 activation by inorganic arsenic in cultured keratinocytes: involvement of hydrogen peroxide Abstract: Inorganic arsenic is a well-documented human carcinogen that targets the skin. The induction of oxidative stress, as shown with arsenic, may have a bearing on the carcinogenic mechanism of this metalloid. The transcription factor Nrf2 is a key player in the regulation of genes encoding for many antioxidative response enzymes. Thus, the effect of inorganic arsenic (as sodium arsenite) on Nrf2 expression and localization was studied in HaCaT cells, an immortalized human keratinocyte cell line. We found, for the first time, that arsenic enhanced cellular expression of Nrf2 at the transcriptional and protein levels and activated expression of Nrf2-related genes in these cells. In addition, arsenic exposure caused nuclear accumulation of Nrf2 in association with downstream activation of Nrf2-mediated oxidative response genes. Arsenic simultaneously increased the expression of Keap1, a regulator of Nrf2 activity. The coordinated induction of Keap1 expression and nuclear Nrf2 accumulation induced by arsenic suggests that Keap1 is important to arsenic-induced Nrf2 activation. Furthermore, when cells were pretreated with scavengers of hydrogen peroxide (H(2)O(2)) such as catalase-polyethylene glycol (PEG-CAT) or Tiron, arsenic-induced nuclear Nrf2 accumulation was suppressed, whereas CuDIPSH, a cell-permeable superoxide dismutase (SOD) mimic compound that produces H(2)O(2) from superoxide (*O(2)(-)), enhanced Nrf2 nuclear accumulation. These results indicate that H(2)O(2), rather than *O(2)(-), is the mediator of nuclear Nrf2 accumulation. Additional study showed that arsenic causes increased cellular H(2)O(2) production and that H(2)O(2) itself has the ability to increase Nrf2 expression at both the transcription and protein levels in HaCaT cells. Taken together, these data clearly show that arsenic increases Nrf2 expression and activity at multiple levels and that H(2)O(2) is one of the mediators of this process.",
Arsenic,1344323,"Cytoskeletal alterations in lipopolysaccharide-induced bovine vascular endothelial cell injury and its prevention by sodium arsenite Abstract: Morphological changes, especially cytoskeletal alterations, in lipopolysaccharide (LPS)-induced vascular endothelial cell injury were studied by using LPS-susceptible bovine aortic endothelial cells (BAEC). BAEC in cultures with LPS showed cell rounding, shrinking, and intercellular gap formation. In those cells, LPS caused the disorganization of actin, tubulin, and vimentin. LPS also induced a reduction in the F-actin pool and an elevation in the G-actin pool. Cytoskeletal disorganization affected transendothelial permeability across the endothelial monolayer. Pretreatment of BAEC with sodium arsenite (SA) prevented alterations in LPS-induced BAEC injury. However, posttreatment with SA had no protective effect on them. SA upregulated the expression of heat shock protein in the presence of LPS. The role of SA in prevention of LPS-induced BAEC injury is discussed.",
Arsenic,1352892,Effect of source water quality on arsenic (V) removal from drinking water by coagulation/microfiltration Abstract: ,
Arsenic,8517,"Metabolism of inorganic arsenic (74As) in humans following oral ingestion Abstract: Oral doses of carrier-free 74As (~6 ?Ci/man; ~0.01 ?g arsenic/man) as arsenic acid were administered to six adult males. Fifty-eight percent of the 74As dose was excreted in the urine in the first 5 days after dosing. The proportion of chemical species of arsenic in the urine was as follows: 51% dimethylarsinic acid, 21% monomethylarsenic compound, and 27% inorganic arsenic.",
Arsenic,1148109,"Aberrant gene expression in liver and liver tumors induced by transplacental exposure to inorganic arsenic Abstract: Arsenic is a known human carcinogen that targets the liver. We have found exposure of pregnant mice to inorganic arsenic in the drinking water induces hepatocellular carcinoma (HCC) in the offspring. In addition, adult mice chronically exposed to inorganic arsenic in the drinking water (37.5 ppm, 48 weeks) show hepatic overexpression of the estrogen receptor-alpha (ER) and cyclin D1 genes, both of which are implicated in hepatocarcinogenesis. Thus, we examined ER and cyclin D1 expression in liver and liver tumors in adult mice that resulted from transplacental exposure to inorganic arsenite (0 or 85 ppm from gestation day 8 to 18). HCC or surrounding normal liver samples were taken at necropsy from control or arsenic-exposed mice which were typically over 1-year-old. Immunohistochemistry revealed the increased expression of ER and cyclin D1 protein in HCC and normal liver of arsenic-exposed mice. Microarray and real time RT-PCR analysis confirmed the increased expression of ER (2.5- to 3.5-fold over control) and cyclin D1 (1.7- to 6.8-fold) at the RNA level in HCC and normal liver after arsenic exposure. Methylation-specific PCR of DNA from HCC and normal liver showed arsenic had induced extensive hypomethylation in the promoter region of the ER gene. To define the human significance of these data, RT-PCR analysis was applied to liver biopsy samples from a population in Guizhou, China, heavily exposed to environmental arsenic that develop HCC. ER and cyclin D1 expression was 2 to 5 times higher with arsenic exposure than in normal human livers. These data show that transplacental arsenic carcinogenesis is linked with enhanced expression of ER and cyclin D1. The overexpression of the ER gene may be due to promoter region hypomethylation. Both ER and cyclin D1 can play important roles in liver tumor formation, and their overexpression may be an important element in the hepatocarcinogenic effects of inorganic arsenic.",
Arsenic,627354,"Immunosuppression by arsenic: A comparison of cathepsin L inhibition and apoptosis Abstract: Arsenicals are toxicants and carcinogens to which large numbers of people risk exposure by contaminated water, air pollution or industrial contact. Several animal studies have determined that inorganic arsenicals are immunotoxic, but the mechanism of immune suppression is not clear. In this study, we show that trivalent arsenic inhibits enzymatic activity of the lysosomal protease cathepsin L (CathL) in the murine antigen-presenting B cell line TA3. CathL plays an important role in antigen processing, the mechanism by which antigen-presenting cells cleave foreign protein antigens to peptides for stimulating a T cell response. Deficient proteolysis may lead to diminished immune responses. Arsenite suppressed enzymatic activity within TA3 cells after 4 h exposure without affecting cell viability. Kinetic analyses revealed that the chemical was a reversible, partially noncompetitive inhibitor of CathL with a Ki of 120 microM. However, an 18 h arsenite exposure triggered massive cell death at concentrations that were substantially lower than those required for enzymatic inhibition. Morphological analysis and annexin V staining showed that arsenite-exposed TA3 cells underwent apoptosis within 18 h, and early stages of apoptosis began by 4 h. These findings suggest that apoptosis may be an important mechanism for arsenic-induced immunosuppression.",
Arsenic,628550,"Human arsenic methyltransferase (AS3MT) pharmacogenetics: Gene resequencing and functional genomics studies Abstract: Arsenic contaminates ground water worldwide. Methylation is an important reaction in the biotransformation of arsenic. We set out to study the pharmacogenetics of human arsenic methyltransferase (AS3MT, previously CYT19). After cloning the human AS3MT cDNA, we annotated the human gene and resequenced its 5'-flanking region, exons, and splice junctions using 60 DNA samples from African-American (AA) and 60 samples from Caucasian-American (CA) subjects. We observed 26 single nucleotide polymorphisms (SNPs), including 3 non-synonymous cSNPs, as well as a variable number of tandem repeats in exon 1 within an area encoding the cDNA 5'-untranslated region. The nonsynonymous cSNPs included T860C (M287T) with frequencies of 10.8 and 10% in AA and CA subjects, respectively, as well as C517T (A173W) in one AA and C917T (T306I) in one CA sample. Haplotype analysis showed that Ile(306) was linked to Thr(287), so this double variant allozyme was also studied functionally. After expression in COS-1 cells and correction for transfection efficiency, the Trp(173) allozyme displayed 31%, Thr(287) 350%, Ile(306) 4.8%, and Thr(287)/Ile(306) 6.2% of the activity of the wild type (WT) allozyme, with 20, 190, 4.4, and 7.9% of the level of WT immunoreactive protein, respectively. Apparent K(m) values for S-adenosyl-l-methionine were 4.6, 3.1, and 11 mum for WT, Trp(173), and Thr(287) allozymes, with K(m) values for sodium arsenite with the same allozymes of 11.8, 8.9, and 4.5mum. The Ile(306) and Thr(287)/Ile(306) allozymes expressed too little activity for inclusion in the substrate kinetic studies. Expression of reporter gene constructs for the 5'-flanking region and the variable number of tandem repeats in the 5'-untranslated region demonstrated cell line-dependent variation in reporter gene expression, with shorter repeats associated with increased transcription in HepG2 cells. These results raise the possibility that inherited variation in AS3MT may contribute to variation in arsenic metabolism and, perhaps, arsenic-dependent carcinogenesis in humans.",
Arsenic,1355106,"Eosinophil apoptosis is mediated by stimulators of cellular oxidative metabolisms and inhibited by antioxidants: Involvement of a thiol-sensitive redox regulation in eosinophil cell death Abstract: The mechanisms for induction of eosinophil apoptosis remain uncertain. The role of oxidative stress has not been investigated. The present study was undertaken to determine the role of reactive oxygen species (ROS) and selective antioxidants in eosinophil apoptosis. Eosinophils were cultured with sodium arsenite (SA) known to induce intracellular oxidative metabolites. There was a significant increase in the rate of eosinophil apoptosis with low concentrations of arsenite, whereas high concentrations showed rates of apoptosis similar to control medium. Investigating the role of intracellular oxidants by flow cytometry, we found that while inducing apoptosis, SA more than anti-Fas resulted in a significant dose-dependent production of intracellular H(2)O(2). In contrast, the extracellular release of superoxide decreased after stimulation with SA or anti-Fas as assessed by lucigenin-dependent chemiluminescence. Coincubation experiments demonstrated that arsenite-induced apoptosis can be nearly completely prevented by selective antioxidants such as glutathione (GSH) and N-acetyl-cysteine (NAC), but not dimethyl sulfoxide (DMSO) or taurine (TAUR). Moreover, GSH and NAC significantly reduced eosinophil apoptosis mediated by a monoclonal antibody directed to Fas antigen. Next it was shown that GSH and NAC, but not DMSO or TAUR, were able to significantly delay spontaneous apoptosis in unstimulated eosinophils. Taken together, these data point to an important role of oxygen-dependent mechanisms in the regulation of eosinophil survival and apoptosis. We propose that eosinophil apoptosis may be related to the ability of the cell to maintain an appropriate oxidant-antioxidant balance.",
Arsenic,1027682,"Induction of preneoplastic lesions by sodium arsenite in human fetal respiratory epithelia in organ culture Abstract: The effects of sodium arsenite (As) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on epithelia of human fetal trachea and bronchiolar epithelia of human fetal lung were studied by using organ-cultured explants. In epithelium of human fetal trachea, 34 microM MNNG induced hyperplasia, metaplasia, and dysplasia; 1 microM As induced hyperplasia; and 3-9 microM As induced hyperplasia and cellular atypia. In glandular epithelium of human fetal trachea, 34 microM MNNG induced hyperplasia and metaplasia; 1 microM As did not induce obvious changes; and 3-9 microM As induced hyperplasia and epidermoid metaplasia with nuclear atypia. In bronchiolar epithelium of human fetal lung, the induction of dysplasia was observed for 1 microM As. Arsenic-induced preneoplastic lesions support the conclusion of epidemiological studies that arsenic is carcinogenic to human lung.",
Arsenic,2337213,"The potential effect of berberine in mercury-induced hepatorenal toxicity in albino rats Abstract: Mercury (Hg) is the third most dangerous heavy metal after arsenic and lead. Mercury's toxicity brings serious risks to health through negative pathological and biochemical effects. The study was designed to investigate the possible protective role of berberine (BN) in mercuric chloride (HgCl2) induced oxidative stress in hepatic and renal tissues. Adult male albino Wistar rats were exposed to mercuric chloride (HgCl2; 0.4mg/kg bwt) for 7days. Treatment with HgCl2 induced oxidative stress by increasing lipid peroxidation and nitric oxide production along with a concomitant decrease in glutathione and various antioxidant enzymes, namely superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. HgCl2 intoxication increased the activities of liver enzymes and the bilirubin level, in addition to the levels of urea and creatinine in serum. BN (100mg/kg bwt) treatment inhibited lipid peroxidation and nitric oxide production, whereas it increased glutathione content. Activities of antioxidants enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, were also restored concomitantly when compared to control after BN administration. BN also inhibited the apoptotic effect of HgCl2 by increasing the expression of Bcl-2 protein in liver and kidney. Histopathological examination of the liver and kidney tissues proved the protective effect of BN against HgCl2 toxicity. These results demonstrated that BN augments antioxidant defense against HgCl2-induced toxicity and provides evidence that it has therapeutic potential as hepato- and reno-protective agent.",
Arsenic,732053,"Metabolism of low-dose inorganic arsenic in a central European population: Influence of sex and genetic polymorphisms Abstract: There is a wide variation in susceptibility to health effects of arsenic, which, in part, may be due to differences in arsenic metabolism. Arsenic is metabolized by reduction and methylation reactions, catalyzed by reductases and methyltransferases.<br /><br /> Our goal in this study was to elucidate the influence of various demographic and genetic factors on the metabolism of arsenic.<br /><br /> We studied 415 individuals from Hungary, Romania, and Slovakia by measuring arsenic metabolites in urine using liquid chromatography with hydride generation and inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS). We performed genotyping of arsenic (+III) methyltransferase (AS3MT), glutathione S-transferase omega 1 (GSTO1), and methylene-tetrahydrofolate reductase (MTHFR).<br /><br /> The results show that the M287T (T-->C) polymorphism in the AS3MT gene, the A222V (C-->T) polymorphism in the MTHFR gene, body mass index, and sex are major factors that influence arsenic metabolism in this population, with a median of 8.0 microg/L arsenic in urine. Females < 60 years of age had, in general, higher methylation efficiency than males, indicating an influence of sex steroids. That might also explain the observed better methylation in overweight or obese women, compared with normal weight men. The influence of the M287T (T-->C) polymorphism in the AS3MT gene on the methylation capacity was much more pronounced in men than in women.<br /><br /> The factors investigated explained almost 20% of the variation seen in the metabolism of arsenic among men and only around 4% of the variation among women. The rest of the variation is probably explained by other methyltransferases backing up the methylation of arsenic.",
Arsenic,627430,"Toxicogenomic analysis of aberrant gene expression in liver tumors and nontumorous livers of adult mice exposed in utero to inorganic arsenic Abstract: Arsenic is a known human carcinogen. We have reported that brief exposure of pregnant C3H mice to arsenite in their drinking water during gestation induced hepatocellular carcinoma (HCC) in male offspring after they became adults. Tumor formation is typically associated with multiple gene expression changes, and this study examined aberrant gene expression associated with transplacental arsenic hepatocarcinogenesis. Liver tumors and nontumorous liver samples were taken at necropsy from adult male mice exposed in utero to either 42.5 or 85 ppm arsenic as sodium arsenite or unaltered water from day 8 to 18 of gestation. Total RNA was extracted and subjected to microarray analysis. Among 600 genes, arsenic-induced HCC showed a higher rate of aberrant gene expression (>2-fold and p < 0.05, 14%) than spontaneous tumors (7.8%). Overexpression of alpha-fetoprotein, c-myc, cyclin D1, proliferation-associated protein PAG, and cytokeratin-18 were more dramatic in arsenic-induced HCC than spontaneous tumors. In nontumorous liver samples of arsenic-exposed animals, 60 genes (10%) were differentially expressed, including the increased expression of alpha-fetoprotein, c-myc, insulin-like growth factor binding protein-1, superoxide dismutase, glutathione S-transferases, and CYP2A4, and the depressed expression of CYP7B1. Real-time RT-PCR analysis largely confirmed these findings. This toxicogenomic analysis revealed several aberrant gene expression changes associated with transplacental arsenic carcinogenesis. It is indeed remarkable that expression changes occurred in adulthood even though arsenic exposure ended during gestation. Some of these aberrantly expressed genes could play a role in the development of arsenic-induced tumors, at least in the liver.",
Arsenic,1244039,"Contributions of natural arsenic sources to surface waters on a high grade arsenic-geochemical anomaly (French Massif Central) Abstract: The subwatershed studied drains a non-exploited area of the St-Yrieix-la-Perche gold mining district (French Massif Central) and it is located on an arsenic (As) geochemical anomaly. In this context, it is important to know the geochemical processes involved in the transfer of As from solid environmental compartments to the aquatic system. The stream showed a temporal variation of dissolved As (As(d)) content from 69.4?g.L(-1) in the low flow period to 7.5?g.L(-1) in the high flow period. Upstream, ground- and wetland waters had As(d) concentrations up to 215 and 169?g.L(-1), respectively. The main representative As sources were determined at the subwatershed scale with in-situ monitoring of major and trace element contents in different waters and single extraction experiments. The As sources to stream water could be regrouped into two components: (i) one As-rich group (mainly in the low flow period) with groundwater, gallery exploration outlet waters and wetland waters, and (ii) one As-poor group (mainly in the high flow period) with rainwaters and soil solutions. In the soil profile, As(d) showed a significant decrease from 52.4?g.L(-1) in the 0-5cm superficial soil horizon to 14.4?g.L(-1) in the 135-165cm deep soil horizon. This decrease may be related to pedogenic processes and suggests an evolution of As-bearing phase stability through the soil profile. Quantification of As(d) fluxes at the subwatershed scale showed that groundwater was the major input (&gt;80%) of As(d) to surface water. Moreover, natural weathering of the As-rich solid phases showed an impact on the As release, mainly from superficial soil horizons with runoff contributing about 5% to As input in surface water.",
Arsenic,1519090,"Effect of organic matter amendment, arsenic amendment and water management regime on rice grain arsenic species Abstract: Arsenic accumulation in rice grain has been identified as a major problem in some regions of Asia. A study was conducted to investigate the effect of increased organic matter in the soil on the release of arsenic into soil pore water and accumulation of arsenic species within rice grain. It was observed that high concentrations of soil arsenic and organic matter caused a reduction in plant growth and delayed flowering time. Total grain arsenic accumulation was higher in the plants grown in high soil arsenic in combination with high organic matter, with an increase in the percentage of organic arsenic species observed. The results indicate that the application of organic matter should be done with caution in paddy soils which have high soil arsenic, as this may lead to an increase in accumulation of arsenic within rice grains. Results also confirm that flooding conditions substantially increase grain arsenic.",
Arsenic,2347802,"Antioxidant activities of chicken liver hydrolysates by pepsin treatment Abstract: This study was divided into two parts: (i) an optimal hydrolysing procedure of chicken liver hydrolysates (CLHs) and (ii) the in vivo antioxidant properties of CLHs via a D-galactose-induced mouse model. A pepsin-to-raw chicken liver mass ratio (1:400, w:w) and 2-h hydrolysing period were chosen to manufacture CLHs based on yield, peptide level and antioxidant effect. Molecular masses of CLHs were lower than 10 kDa. CLH was rich in aspartic acid and glutamic acid, and also contained both manganese and selenium, which are essential cofactors of superoxide dismutase and glutathione peroxidase, respectively. The contents of cadmium, mercury, tin, and arsenic in CLHs were very low and even no detectible. Regarding the in vivo antioxidant activity of CLHs, a dosage of 1.2 g D-galactose kg(-1) body weight increased (P &lt; 0.05) 2-thiobarbituric acid reactive substances values and decreased (P &lt; 0.05) glutathione and Trolox equivalent antioxidant capacity values, as well as superoxide dismutase, catalase, and glutathione peroxidase activities in serum and organs of mice. However, the in vivo antioxidant capacities were improved (P &lt; 0.05) by supplementing CLHs.",
Arsenic,628143,"Induction of DNA strand breaks, DNA-protein crosslinks and sister chromatid exchanges by arsenite in a human lung cell line Abstract: Based on in vitro studies, several modes of action for arsenic have been suggested, although the mechanisms responsible for arsenic carcinogenesis have not been well established. In our previous study a dose-dependent increment in DNA migration was detected at low doses of sodium arsenite, but at higher dose levels a reduction in the migration was observed, suggesting the induction of DNA adducts. In order to confirm this hypothesis we performed the experiments considering other parameters and modifications of the standard alkaline comet assay. Additionally, the induction of sister chromatid exchanges was evaluated. The present study showed the induction by sodium arsenite of single strand breaks and DNA-protein adducts assessed by comet assay as well as of sister chromatid exchanges in the human lung fibroblast cell line MRC-5. The standard alkaline comet assay also revealed, at the highest arsenic concentration tested, a reduction in all the considered parameters in relation to untreated cells and the other doses. On the other hand, the incubation with proteinase K induced a dose-dependent increment in DNA migration as a consequence of the release of proteins joined to the DNA. Thus, sodium arsenite was able to induce both DNA-strand breaks and protein-DNA adducts in arsenic exposed MRC-5 cells, depending on the concentrations of arsenic salts tested.",
Arsenic,1020511,"Porphyrin profiles in blood and urine as a biomarker for exposure to various arsenic species Abstract: A sensitive method using HPLC with fluorescence detection has been established for the measurement of porphyrins in biological materials. The assay recoveries were 88.0+/-1.8% for protoporphyrin IX in the blood, and ranged from 98.3+/-2.7% to 111.1+/-7.4% for various porphyrins in the urine. This method was employed to investigate the altered porphyrin profiles in rats after a single dose of various arsenicals including soluble sodium arsenate and sodium arsenite, and the relatively insoluble calcium arsenite, calcium arsenate and arsenic-contaminated soils at dose rates of 5 mg/kg or 0.5 mg/kg body weight. Porphyrin concentrations increased within 2448 hr after the arsenic treatment in blood and urine. Protoporphyrin IX is the predominant porphyrin in the blood. In rats administered 5 mg As(III)/kg body weight, protoporphyrin IX concentration elevated to 123% of the control values in rats, 24 hr after the treatment. Higher increases were recorded in the urinary protoporphyrin IX (253% at 24 hr; 397% on day 2), uroporphyrin (121% at 24 hr; 208% on day 2) and coproporphyrin III (391% at 24 hr; 304% on day 2), while there was no significant increase (109% on day 3) observed in the urinary coproporphyrin I excretion. In rats administered 5 mg As(V)/kg, urinary excretion of protoporphyrin LX, uroporphyrin, coproporphyrin III and coproporphyrin I elevated to the maximum levels by 48 hr with the corresponding percentage values compared to the control being 177%, 158%, 224% and 143%, respectively. In rats dosed with 5 mg As(III)/kg, the increases (expressed as % of the control values) of protoporphyrin IX in the blood were in the order: sodium arsenite (144%) &gt; sodium arsenate (125%) &gt; calcium arsenite (123%) &gt; calcium arsenate. In contrast, there was no significant increase of protoporphyrin IX, when the six arsenic-contaminated cattle dip soils and nine copper chrome arsenate (CCA-contaminated) soils were administered to the rats. Probable explanations are discussed.",
Arsenic,1345147,"[Induction of a geochemical barrier for As, Fe, and S immobilization in a sulfide substrate] Abstract: Acid mine drainage (AMD) is an environmental concern due to the risk of element mobilization, including toxic elements, and inclusion in the food chain. In this study, three cover layers were tested to minimize As, Fe and S mobilization from a substrate from former gold mining, containing pyrite and arsenopyrite. For this purpose, different layers (capillary break, sealant and cover layer) above the substrate and the induction of a geochemical barrier (GB) were used to provide suitable conditions for adsorption and co-precipitation of the mobilized As. Thirteen treatments were established to evaluate the leaching of As, Fe and S from a substrate in lysimeters. The pH, As, Fe, S, Na, and K concentrations and total volume of the leachates were determined. Mineralogical analyses were realized in the substrate at the end of the experimental period. Lowest amounts of As, Fe and S (average values of 5.47, 48.59 and 132.89 g/lysimeter) were leached in the treatments that received Na and K to induce GB formation. Mineralogical analyses indicated jarosite formation in the control treatment and in treatments that received Na and K salts. However, the jarosite amounts in these treatments were higher than in the control, suggesting that these salts accelerated the GB formation. High amounts of As, Fe and S (average values of 11.7, 103.94 and 201.13 g/lysimeter) were observed in the leachate from treatments without capillary break layer. The formation of geochemical barrier and the use of different layers over the sulfide substrate proved to be efficient techniques to decrease As, Fe and S mobilization and mitigate the impact of acid mine drainage. Acid mine drainage (AMD) is an environmental concern due to the risk of element mobilization, including toxic elements, and inclusion in the food chain. In this study, three cover layers were tested to minimize As, Fe and S mobilization from a substrate from former gold mining, containing pyrite and arsenopyrite. For this purpose, different layers (capillary break, sealant and cover layer) above the substrate and the induction of a geochemical barrier (GB) were used to provide suitable conditions for adsorption and co-precipitation of the mobilized As. Thirteen treatments were established to evaluate the leaching of As, Fe and S from a substrate in lysimeters. The pH, As, Fe, S, Na, and K concentrations and total volume of the leachates were determined. Mineralogical analyses were realized in the substrate at the end of the experimental period. Lowest amounts of As, Fe and S (average values of 5.47, 48.59 and 132.89 g/lysimeter) were leached in the treatments that received Na and K to induce GB formation. Mineralogical analyses indicated jarosite formation in the control treatment and in treatments that received Na and K salts. However, the jarosite amounts in these treatments were higher than in the control, suggesting that these salts accelerated the GB formation. High amounts of As, Fe and S (average values of 11.7, 103.94 and 201.13 g/lysimeter) were observed in the leachate from treatments without capillary break layer. The formation of geochemical barrier and the use of different layers over the sulfide substrate proved to be efficient techniques to decrease As, Fe and S mobilization and mitigate the impact of acid mine drainage.",
Arsenic,1019470,"Selenium effects on gallium arsenide induced biochemical and immunotoxicological changes in rats Abstract: The influence of selenium (6.3 and 12.6 micromol/kg, intraperitoneally) on the disposition of gallium and arsenic and a few gallium arsenide (GaAs) sensitive biochemical variables was studied in male rats. Concomitant administration of Se and GaAs (70 micromol/kg, orally, 5 days a week for 4 weeks) significantly prevented the accumulation of arsenic while, the gallium concentration reduced moderately in the soft organs. The biochemical (haematopoietic and liver) and immunological variables however, responded less favorably to selenium administration. Most of the protection was however observed with the dose of 12.6 micromol rather than at 6.3 micromol. The results thus suggest a few beneficial effects of selenium in preventing the appearance of signs of GaAs toxicity like preventing inhibition of blood delta-aminolevulinic acid dehydratase (ALAD), hepatic malondialdehyde (MDA) formation and the accumulation of gallium and arsenic concentration.",
Arsenic,2298708,"Arsenate stabilized Cu2O nanoparticle catalyst for one-electron transfer reversible reaction Abstract: The befitting capping capabilities of AsO4(3-) provide a stable Cu2O nanocatalyst from a galvanic reaction between a Cu(ii) precursor salt and As(0) nanoparticles. This stable Cu2O hydrosol appears to be a suitable catalyst for the one-electron transfer reversible redox reaction between Eosin Y and NaBH4. The progress of the reaction relates to three different kinetic stages. In the presence of the new catalyst the reversible redox reaction of Eosin Y in air shows a periodic color change providing a new crowd-pleasing demonstration, i.e. a &quot;clock reaction&quot;.",
Arsenic,1508622,"Differential toxicity and gene expression in Caco-2 cells exposed to arsenic species Abstract: Inorganic arsenic [As(V)+As(III)] and its metabolites, especially the trivalent forms [monomethylarsonous acid, MMA(III), and dimethylarsinous acid, DMA(III)], are considered the forms of arsenic with the highest degree of toxicity, linked to certain types of cancer and other pathologies. The gastrointestinal mucosa is exposed to these forms of arsenic, but it is not known what toxic effect these species may have on it. The aim of the present work was to evaluate the toxicity and some mechanisms of action of inorganic arsenic and its metabolites [monomethylarsonic acid, MMA(V), dimethylarsinic acid, DMA(V), MMA(III) and DMA(III)] in intestinal epithelial cells, using the Caco-2 human cell line as a model. The results show that the pentavalent forms do not produce toxic effects on the intestinal monolayer, but the trivalent species have a different degree of toxicity. As(III) induces death mainly by necrosis, whereas only apoptotic cells are detected after exposure to MMA(III), and for DMA(III) the percentages of apoptosis and necrosis are similar. The three forms produce reactive oxygen species, accompanied by a reduction in intracellular GSH and lipid peroxidation, the latter being especially notable in the dimethylated form. They also alter the enzyme activity of glutathione peroxidase and catalase and induce expression of stress proteins and metallothioneins. The results indicate that the trivalent forms of arsenic can affect cell viability of intestinal cells by mechanisms related to the induction of oxidative stress. Further studies are needed to evaluate how the effects observed in this study affect the structure and functionality of the intestinal epithelium.",
Arsenic,1797793,"Self-catalyzed VLS grown InAs nanowires with twinning superlattices Abstract: We report on the self-catalyzed growth of InAs nanowires by molecular beam epitaxy on GaAs substrates covered by a thin silicon oxide layer. Clear evidence is presented to demonstrate that, under our experimental conditions, the growth takes place by the vapor-liquid-solid (VLS) mechanism via an In droplet. The nanowire growth rate is controlled by the arsenic pressure while the diameter depends mainly on the In rate. The contact angle of the In droplet is smaller than that of the Ga droplet involved in the growth of GaAs nanowires, resulting in much lower growth rates. The crystal structure of the VLS grown InAs nanowires is zinc blende with regularly spaced rotational twins forming a twinning superlattice.",
Arsenic,1034796,"Losses of arsenic during the low temperature ashing of atmospheric particulate samples Abstract: HEEP COPYRIGHT: BIOL ABS. Neutron activation and atomic absorption procedures were used to study As losses during low temperature ashing at power levels between 50-125 W (RF). Losses of As from ambient atmospheric particulate matter and various synthetic sea salt matrices containing known quantities of As was observed. Generally, the magnitude of As losses by this treatment depends on applied power levels and the physical and chemical properties of the As sample matrix.",
Arsenic,1330941,"A novel approach using DNA-repair-deficient chicken DT40 cell lines for screening and characterizing the genotoxicity of environmental contaminants Abstract: <strong>BACKGROUND: </strong>Many bacterial or mammalian cell-based test systems, such as the Ames test, chromosomal aberration assays, or gene mutation assays, are commonly used in developed countries to detect the genotoxicity of industrial chemicals. However, the specificity is generally limited and the sensitivity is not sufficiently high. In addition, most assays cannot provide information on mechanisms of genotoxicity of a given chemical.<br /><br /><strong>OBJECTIVES: </strong>We aimed to establish a sensitive and fast screening method that is also capable of characterizing mechanisms of genotoxicity.<br /><br /><strong>METHODS: </strong>We developed a novel bioassay employing gene-disrupted clones of the chicken DT40 B-lymphocyte line, which are designed to be deficient in several specific DNA repair pathways. Genotoxic chemicals can delay cellular proliferation in DNA-repair-deficient clones more significantly than in wild-type cells by interfering with DNA replication, thereby inducing DNA damage. In addition, we verified the validity of this assay by analyzing the genotoxicity of gamma-rays, ultraviolet (UV) light, and sodium metaarsenite (NaAsO(2)). We also characterized DNA lesions induced by NaAsO(2).<br /><br /><strong>RESULTS: </strong>Genotoxicity of given stressors was successfully screened based on a comparison of proliferation kinetics between wild-type and DNA-repair-deficient mutants in 48 hr. We also found that NaAsO(2) apparently induces at least two types of damage: chromosomal breaks and UV photoproduct-like DNA lesions.<br /><br /><strong>CONCLUSION: </strong>This bioassay is a reliable and sensitive screening tool for environmental mutagens as well as for further characterizing the nature of detected genotoxicity.",
Arsenic,2337149,"Melatonin protective role in mouse cauda epipidymal spermatozoa damage induced by sodium arsenite Abstract: We evaluated the sperm parameters such as cauda epididymis weight, sperm count, sperm morphology and sperm DNA stability of adult CF-1 male mice treated daily (oral exposure) with the toxic sodium arsenite (As, 7.0 mg/kg/body weight); Melatonin (Me, 10.0 mg/kg/bw), Me (10.0 mg/kg/bw) plus As (7.0 mg/kg/bw) and Negative Control (NaCl 0.9%) to assess acute (8.3 days), chronic (33.2 days) and recovery of testicular damage (66.4 days). Arsenic decreases the number of sperm from chronic treatment (33.2 days) and this effect continued until 66.4 days of treatment. The toxic effect of As also altered the morphology of spermatozoa in all treatment periods when compared to the negative control group. However, Metalonin induced protective effects in periods of 33.2 and 66.4 days of treatment. Additionally, the stability of DNA was significantly affected by arsenic in all periods, but the chronic treatment (33.2 days) in the AsMe revealed increased stability compared to the group treated with arsenic only. Melatonin partially protects sperm toxicity caused by Arsenic, especially during periods of 33.2 and 66.4 days.",
Arsenic,2064194,"Development and validation of an analytical method for quantification of arsenic and antimony in liposomes using inductively coupled plasma-optical emission spectrometry Abstract: Arsenic and antimony compounds are used to treat endemic diseases, such as cancer, leishmaniasis, and schistosomiasis, in spite of their toxicity. Several studies seeking the development and characterization of nanocarrier systems such as liposomes are being carried out with the aim of developing new drug delivery systems and minimizing the toxicity of these drugs. However, the lack of reference methods to quantify these semimetals within a liposomal matrix hinders the QC of these formulations. Therefore, the validation of an analytical method for arsenic and antimony quantification in liposomal matrix by inductively coupled plasma-optical emission spectrometry is presented here. The linearity, specificity, LOD, LOQ, accuracy, and precision were determined according to the International Conference on Harmonization norms and the Brazilian Health Surveillance Agency (Resolution 899). The LOD values were 0.02 and 0.06 mg/L for antimony and arsenic, respectively. The LOQ for both was 3.0 mg/L, with an adequate accuracy within 98.26 and 101.32% for different levels of antimony and 99.98 and 100.36% for arsenic. Precision (CV) was lower than 5.0%. The developed and validated method was shown to be reproducible for quantification of arsenic and antimony in liposome pharmaceutical dosage forms.",
Arsenic,1378508,"Immunological enhancement of chemotherapy in advanced brain cancer Abstract: Three hundred C3H mice were used to ascertain the validity of treatment of brain cancer with arsenicals and bacterial polysaccharide. It was found that this method of therapy was efficacious. Also, that a prophylactic effect was demonstrated. 2. In 14 patients with advanced intracranial neoplasm it was found: a) that no curative effect could be brought about once the cancer had spread beyond a certain point. This &quot;point of no return&quot; depends on tumor type, location and degree of brain destruction and general state of debility. b) That subjective and even some temporary objective improvement was possible even in advanced cancer. Necrosis of cancer tissue, that could be attributed to the therapy, was found in a number of cases. c) That some cases of brain cancer showed remarkable response to this form of therapy; more so if radiation therapy was given at the time of administration of the arsenical and bacterial polysaccharide. d) That some cases of brain metastasis showed &quot;complete&quot; destruction of the neoplasms in the brain although the patient subsequently died of the primary neoplasm and multiple metastasis. e) That the principle of enhancing the deposition of the curative material in the neoplasm by the use of bacterial polysaccharide is valid. f) That if this method of treatment (i.e. arsenical, bacterial polysaccharide and radiation) is instituted in the &quot;early&quot; cancer cases we may find it to be an efficacious mode of attack. g) That aresnical by mouth and bacterial polysaccharide by I.M. injection may be useful as a prophylactic to the formation of cancer. This may be contemplated for use in families that seem to show a predisposition to cancer formation. A mode of administration would probably be somewhat similary to the maintencance therapy described in the body of this paper. h) That bacterial polysaccharides have been shown to have the ability to destroy cancers.3,9 This method of enhancing the patients antigen-antibody reaction may eventually be used as a means of gaining an efficient vaccine in cancer therapy. i) Wherever possible definitive surgery should be carried out before the arsenical-bacterial polysaccharide-radiation method is instituted. j) In brain cancer, after craniotomy with removal of all or part of the neoplasm where feasible, the patient should be left with a subtemporal decompression. This will allow for the oedema of the brain that occurs with cerebral radiation therapy. k) That the principle of destruction of the cancer by certain special substances is valid. That the increase of affinity between cancer and destructive (curative) material can be brought about by administering a bacterial polysaccharide at the same time and that radiation therapy may enhance the beneficial effects of this method. 1) That the principle of brining the greatest toxicity to the cancer cells and the least toxic effect to the organism has been applied in the use of this method of treatment. m) That in some cases the cancer may not be destroyed by this therapy but may be made to retrogress or be held in check.",
Arsenic,2337068,"Paragenesis and composition of ore minerals in the Randalls BIF-hosted gold deposits, Yilgarn Craton, Western Australia: Implications for the timing of deposit formation and constraints on gold sources Abstract: The Randalls district comprises three individual gold deposits - Cock-Eyed Bob, Maxwells, and Santa-Craze - hosted in the same unit of banded iron-formation (BIF) in the southern Eastern Goldfields Superterrane, Yilgarn Craton, Western Australia. The iron formation is a silicate/oxide-facies unit with overprinting sulfides, and has undergone metamorphism (upper-greenschist fades) and deformation (two generations of folds). The gold deposits are hosted in two structural locations: hinge zones of anticlinal folds (e.g., Santa-Craze and Maxwells) and overturned, steeply dipping limbs of anticlinal folds (e.g., Cock-Eyed Bob). Gold dominantly occurs as inclusions of native gold and/or electrum within or around pyrrhotite, magnetite, and arsenopyrite. <br> <br>The earliest mineral assemblage preserved in the banded iron formation at Randalls is banded magnetite-quartz. Magnetite in all forms has elevated Mg, Al, Ti, V, Mn, Cr, Zn, and W, but very low Ni compared to other BIFs globally. Pyrrhotite, the most abundant sulfide, is restricted to ore zones and occurs as laminae, ""blebs"", and veinlets, all of which have replaced magnetite. Some pyrrhotite in the hydrothermally altered BIFs (especially in near-surface samples) has been re-sulfidized to pyrite. Trace elements associated with pyrrhotite include Co, Ni, Ag, Sb, and Pb. Large, coarse-grained arsenopyrite overgrows the pyrrhotite-defined foliation; it is enriched in Co, Ni, Sb, and Te, but contains very little 'invisible' gold (&lt;0.01 ppm Au), unlike arsenopyrite in many orogenic Au systems globally (commonly &gt;= 0.1 ppm Au). <br> <br>Petrographic studies of several mineralized BIFs from Randalls reveal that pyrrhotite and arsenopyrite are associated with Fe(-Ca) amphibole, which grew during contact metamorphism caused by granite plutons. This spatial sulfide-amphibole relationship indicates that gold mineralization likely occurred during granite intrusion, consistent with prior studies on Randalls. The trace element characteristics of the sulfides show that they were not inherited from replaced magnetite. Further, these characteristics suggest that the fluid from which sulfides crystallized was not indigenous to the BIFs, and that this S-rich fluid either contained S in abundance originally, or interacted with a lithology/lithologies that were rich in S before reaching the BIFs. Black shale containing diagenetic nodular pyrite occurs in the upper Black Flag Group, which unconformably underlies the Belches Supersequence at depth (similar to 3 km). The trace element composition of nodular pyrite from this unit fits well with the trace element characteristics of the BIF pyrrhotite and arsenopyrite, and the nodular pyrite contains an average of 0.5 ppm Au. However, the nodular pyrites have an average delta S-34 value of 5.6 parts per thousand (n = 13), which contrasts markedly with the delta S-34 average of pyrrhotite, pyrite and arsenopyrite in mineralized BIFs (0.8 parts per thousand, n = 17). Thus, a definitive source of gold, arsenic, silver, and tellurium in the Randalls system remains elusive, although we would contend that the upper Black Flag Group should be considered as a possible metal and S source in areas of the Yilgarn where it forms a thick substrate to ore camps. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,1579279,"Biomarkers for the evaluation of population health status 16 years after the intervention of arsenic-contaminated groundwater in Xinjiang, China Abstract: The arsenicosis endemic area in the region of Kuitun and Chepaizi, Dzungaria district, Xinjiang, People Republic of China was the first identified arsenic endemic area in China where arsenic concentration of up to 850?g/L in the groundwater was reported. An intervention was put in place in 1985 by government to provide an alternative water source at a centralized community level. Sixteen years on since the intervention, we evaluated the health status of 178 villagers from endemic and 179 villagers from control sites. Biomarkers in their urine, included arsenic, porphyrins and malondialdehyde (MDA) were measured and the prevalence of skin lesions was also assessed. The average urinary arsenic (117±8.3?g/g of creatinine) from the endemic-villages was significantly higher (p&lt;0.001) than that of the controls (73.6±3.2?g/g of creatinine) while no significant difference was found in urinary porphyrins and malondialdehyde concentrations in the overall studies subjects from these two areas. However when the urinary arsenic was higher than 150?g/g of creatinine, MDA and porphyrins were higher in the endemic-villagers compared to the controls. Fifty-one out of 178 people from the arsenic endemic area showed skin lesions related to arsenicosis but these were absent among villagers from the control site. Of particular concern, skin lesions related to arsenicosis were observed in 4 out of 9 subjects 16 years of age or younger who were from different villages and born after the completion of water intervention. Although sporadic exposure and/or voluntary drinking contaminated water were thought to be a contributor of arsenicosis after the water intervention, the contribution from other dietary arsenic intakes remain unclear.",
Arsenic,1015765,"Low levels of arsenic in drinking water and type 2 diabetes in Middle Banat region, Serbia Abstract: Arsenic in drinking water presents a serious public health problem in Serbia, but its relationship with diabetes has not been studied previously. The aim of this study was to explore the association between exposure to arsenic in drinking water and the occurrence of type 2 diabetes in Middle Banat region, Serbia. This cross-sectional study comprised two populations. Exposed population in Middle Banat region consumes drinking water with arsenic (mean=56?g/L); unexposed population from six regions in Central Serbia consumes arsenic below detection limit (2?g/L). Newly diagnosed cases of type 2 diabetes were obtained from the National Registry of Diabetes in 2008. The Registry included age, gender, family history of diabetes, presence of overweight, central obesity, cholesterol and triglyceride levels. In addition, the number of cases of diabetes reported in years 2006, 2007 and 2009 was used to calculate standardized incidence rates for both populations. Two populations were comparable by age, family history of diabetes and prevalence of overweight persons. Unexposed population was more likely to have central obesity, and high total cholesterol and triglycerides. Standardized incidence rates of type 2 diabetes were higher in exposed population. Odds ratios for type 2 diabetes were significantly higher for the exposed population, both men and women, in the period from 2006 to 2009, when compared with the unexposed population. The population from Middle Banat region, consuming drinking water with low levels of arsenic, was at higher risk for the occurrence of type 2 diabetes in comparison to the unexposed population in Central Serbia.",
Arsenic,1354203,A SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF MICRO-QUANTITIES OF ARSENIC IN DIFFERENT BIOLOGICAL-MATERIALS - SILVER DIETHYLDITHIOCARBAMATE IN PYRIDINE AS THE REAGENT FOR COLOR DEVELOPMENT Abstract: ,
Arsenic,2347601,"Arsenic in Rice - A Cause for Concern. A Comment by the ESPGHAN Committee on Nutrition Abstract: Inorganic arsenic intake is likely to affect long-term health. High concentrations are found in some rice-based foods and drinks widely used in infants and young children. In order to reduce exposure we recommend avoidance of rice drinks for infants and young children. For all rice products, strict regulation should be enforced regarding arsenic content. Moreover, infants and young children should consume a balanced diet including a variety of grains as carbohydrate sources. While rice protein based infant formulas are an option for infants with cows' milk protein allergy, the inorganic arsenic content should be declared and the potential risks should be considered when using these products.",
Arsenic,710913,"Effects of arsenic exposure during the pre- and postnatal development on the puberty of female offspring Abstract: The (As) arsenic exposure is a risk factor for causing disturbances in the endocrine organs. OBJECTIVE: To evaluate if sub-chronic As exposure during the pre- and postnatal development causes disturbances in the puberty. Moreover, determine adverse effects of As on the ovarian follicle and adrenocortical cell maturation. METHODS: Females adult Wistar rats were exposed to sodium arsenite at 3ppm calculated as As in drinking water from mating, gestation. Following the birth, the female offspring continued exposured to As via lactation. Weaned pups received the same As treatment as mothers, until they were 1-4 months (mo) old. At these ages, blood sampling and tissue harvest were done. The tissues were fixed in situ with 4% paraformaldehyde in phosphate buffer. After the perfusion the ovaries, uterus, adrenal glands were harvested, dissected out, weighted. The ovaries and the adrenal glands were processed to paraffin and sectioned at 5muM and stained with hematoxylin and eosin for light microscopy. STATISTICAL ANALYSIS: Comparisons between groups were made by unpaired t-test or nonparametric Mann-Whitney test as appropriate. RESULTS: 100% As treated rats at 1 mo of age were at diestrous stage, with low estradiol E2. As treatment caused disturbances in the morphology of the ovarian cell consisting in DNA damage evidenced by picknotic chromatin, cariorexis, significant cytoplasmic vacuolization and also vasculature damaged. Arrest in follicle maturation was also present. CONCLUSIONS: We found that the onset of puberty in the As treated rats was 1 mo delayed since vagina was still closed, the vaginal smear showed that they were at diestrus stage with plasma low E2 levels.",
Arsenic,2279403,"A prospective cohort study of stroke mortality and arsenic in drinking water in Bangladeshi adults Abstract: <strong>BACKGROUND: </strong>Arsenic in drinking water causes increased coronary artery disease (CAD) and death from CAD, but its association with stroke is not known.<br /><br /><strong>METHODS: </strong>Prospective cohort study with arsenic exposure measured in well water at baseline. 61074 men and women aged 18 years or older on January 2003 were enrolled in 2003. The cohort was actively followed for an average of 7 years (421,754 person-years) through December 2010. Based on arsenic concentration the population was categorized in three groups and stroke mortality HR was compared to the referent. The risk of stroke mortality Hazard Ratio (HR) and 95% Confidence Interval was calculated in relation to arsenic exposure was estimated by Cox proportional hazard models with adjustment for potential confounders.<br /><br /><strong>RESULTS: </strong>A total of 1033 people died from stroke during the follow-up period, accounting for 23% of the total deaths. Multivariable adjusted HRs (95% confidence interval) for stroke for well water arsenic concentrations &lt;10, 10-49, and ?50 ?g/L were 1.0 (reference), 1.20 (0.92 to 1.57), and 1.35 (1.04 to 1.75) respectively (Ptrend=0.00058). For men, multivariable adjusted HRs (95%) for well water arsenic concentrations &lt;10, 10-49, and ?50 ?g/L were 1.0 (reference), 1.12 (0.78 to 1.60), and 1.07 (0.75 to 1.51) respectively (Ptrend=0.45) and for women 1.0 (reference),1.31 (0.87 to 1.98), and 1.72 (1.15 to 2.57) respectively (Ptrend=0.00004).<br /><br /><strong>CONCLUSION: </strong>The result suggests that arsenic exposure was associated with increased stroke mortality risk in this population, and was more significant in women compared to men.",
Arsenic,1346531,"The transcriptional regulation and cell-specific expression of the MAPK-activated protein kinase MK5 Abstract: The mitogen-activated protein kinase (MAPK) cascades regulate important cellular processes, including growth, differentiation, apoptosis, embryogenesis, motility and gene expression. Although MAPKs mostly appear to be constitutively expressed, the transcript levels of some MAPK-encoding genes increase upon treatment with specific stimuli. This applies to the MAPK-activated protein kinases MK2 and MK3. By contrast, the transcriptional regulation of the related MK5 has not yet been studied. The MK5 promoters of mouse, rat and human contain a plethora of putative transcription factor sites, and the spatio-temporal expression of MK5 suggests inducible transcription of the gene. We examined the transcription pattern of MK5 in different tissues, and studied the kinetics of MK5 expression at the transcriptional and/or translation level in PC12 cells exposed to arsenite, forskolin, KCl, lipopolysaccharide, spermine NONOate, retinoic acid, serum, phorbol ester, temperature shock, and vanadate. Cells exposed to forskolin display a transient increase in MK5 mRNA, despite their unaltered MK5 protein levels. The MK5 promoters of human, mouse and rat contain a cAMP-responsive element that binds the cAMP-responsive element-binding protein (CREB) in vitro. Luciferase reporter constructs containing an 850-base pair human MK5 promoter fragment encompassing the CRE showed a basal activity that was 10-fold higher than the corresponding construct in which the CRE motif was deleted. siRNA-mediated depletion of CREB had no effect on the endogenous MK5 protein levels. Several binding motifs for heat shock factor are dispersed in the mouse and rat promoter, and temperature shock transiently enhanced the MK5 transcript levels. None of the other tested stimuli had an effect on the MK5 mRNA or protein levels. Our results indicate an inducible regulation of MK5 transcription in response to specific stimuli. However, the MK5 protein levels remained unaffected by all the stimuli tested. There is still no explanation for the discrepancy between the increased mRNA and unchanged MK5 protein levels.",
Arsenic,1016412,"Arsenic metabolism by human gut microbiota upon in vitro digestion of contaminated soils Abstract: <strong>BACKGROUND: </strong>Speciation analysis is essential when evaluating risks from arsenic (As) exposure. In an oral exposure scenario, the importance of presystemic metabolism by gut microorganisms has been evidenced with in vivo animal models and in vitro experiments with animal microbiota. However, it is unclear whether human microbiota display similar As metabolism, especially when present in a contaminated matrix.<br /><br /><strong>OBJECTIVES: </strong>We evaluated the metabolic potency of in vitro cultured human colon microbiota toward inorganic As (iAs) and As-contaminated soils.<br /><br /><strong>METHODS: </strong>A colon microbial community was cultured in a dynamic model of the human gut. These colon microbiota were incubated with iAs and with As-contaminated urban soils. We determined As speciation analysis using high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry.<br /><br /><strong>RESULTS: </strong>We found a high degree of methylation for colon digests both of iAs (10 microg methylarsenical/g biomass/hr) and of As-contaminated soils (up to 28 microg/g biomass/hr). Besides the formation of monomethylarsonic acid (MMA(V)), we detected the highly toxic monomethylarsonous acid (MMA(III)). Moreover, this is the first description of microbial thiolation leading to monomethylmonothioarsonic acid (MMMTA(V)). MMMTA(V), the toxicokinetic properties of which are not well known, was in many cases a major metabolite.<br /><br /><strong>CONCLUSIONS: </strong>Presystemic As metabolism is a significant process in the human body. Toxicokinetic studies aiming to completely elucidate the As metabolic pathway would therefore benefit from incorporating the metabolic potency of human gut microbiota. This will result in more accurate risk characterization associated with As exposures.",
Arsenic,628049,"Neovascularization and angiogenic gene expression following chronic arsenic exposure in mice Abstract: Exposure to arsenic in drinking water increases incidence of cardiovascular diseases. However, the basic mechanisms and genetic changes that promote these diseases are unknown. This study investigated the effects of chronic arsenic exposure on vessel growth and expression of angiogenic and tissue remodeling genes in cardiac tissues. Male mice were exposed to low to moderately high levels of arsenite (AsIII) for 5, 10, or 20 wk in their drinking water. Vessel growth in Matrigel implants was tested during the last 2 wk of each exposure period. Implant vascularization increased in mice exposed to 5-500 ppb AsIII for 5 wk. Similar increases were seen following exposure to 50-250 ppb of AsIII over 20 wk, but the response to 500 ppb decreased with time. RT-PCR analysis of cardiac mRNA revealed differential expression of angiogenic or tissue remodeling genes, such as vascular endothelial cell growth factor (VEGF), VEGF receptors, plasminogen activator inhibitor-1, endothelin-1, and matrix metalloproteinase-9, which varied with time or amount of exposure. VEGF receptor mRNA and cardiac microvessel density were reduced by exposure to 500 ppb AsIII for 20 wk. These data demonstrate differential concentration and time-dependent effects of chronic arsenic exposure on cardiovascular phenotype and vascular remodeling that may explain the etiology for AsIII-induced disease.",
Arsenic,2149092,"Arsenate and cadmium co-adsorption and co-precipitation on goethite Abstract: Arsenate (As(V), AsO4(3-)) and cadmium (Cd) are among the toxic elements of most concern. Their sorption behaviors on goethite were studied by batch experiments (pH edges, isotherms and kinetics) and X-ray diffraction (XRD). Arsenic coordination environment was explored by X-ray absorbance fine structure (EXAFS) analysis. Sorption isotherms of both As(V) and Cd on goethite could be divided into the adsorption-dominated and precipitation-dominated parts, while their sorption showed different pH-dependency and sorption reversibility. Cadmium adsorption was enhanced in the presence of AsO4(3-), which could be explained by the decrease in the electrostatic potential due to the sorption of AsO4(3-) and the formation of a ternary Cd-As(V)-goethite complex. Based on the EXAFS study, AsO4(3-) adsorbed on goethite mainly formed bidentate-binuclear complex. The high loadings of Cd changed the As(V)-Fe distance and its coordination number. However, Cd did not affect the As(V) adsorption amount in the adsorption-dominated region. When As(V) and Cd formed co-precipitates, their sorption amounts were both increased. The formation of co-precipitates decreased the mobility of Cd but increased the mobility of As(V) because less As(V) was sorbed on goethite through surface complexation. This study will provide better understandings on As(V) and Cd transport and useful information on their remediation strategies.",
Arsenic,710846,"Arsenic: Toxicity, oxidative stress and human disease Abstract: Arsenic (As) is a toxic metalloid element that is present in air, water and soil. Inorganic arsenic tends to be more toxic than organic arsenic. Examples of methylated organic arsenicals include monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)]. Reactive oxygen species (ROS)-mediated oxidative damage is a common denominator in arsenic pathogenesis. In addition, arsenic induces morphological changes in the integrity of mitochondria. Cascade mechanisms of free radical formation derived from the superoxide radical, combined with glutathione-depleting agents, increase the sensitivity of cells to arsenic toxicity. When both humans and animals are exposed to arsenic, they experience an increased formation of ROS/RNS, including peroxyl radicals (ROO•), the superoxide radical, singlet oxygen, hydroxyl radical (OH•) via the Fenton reaction, hydrogen peroxide, the dimethylarsenic radical, the dimethylarsenic peroxyl radical and/or oxidant-induced DNA damage. Arsenic induces the formation of oxidized lipids which in turn generate several bioactive molecules (ROS, peroxides and isoprostanes), of which aldehydes [malondialdehyde (MDA) and 4-hydroxy-nonenal (HNE)] are the major end products. This review discusses aspects of chronic and acute exposures of arsenic in the etiology of cancer, cardiovascular disease (hypertension and atherosclerosis), neurological disorders, gastrointestinal disturbances, liver disease and renal disease, reproductive health effects, dermal changes and other health disorders. The role of antioxidant defence systems against arsenic toxicity is also discussed. Consideration is given to the role of vitamin C (ascorbic acid), vitamin E (?-tocopherol), curcumin, glutathione and antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase in their protective roles against arsenic-induced oxidative stress.",
Arsenic,1240168,"Ion exchange treatment of groundwater contaminated by arsenic in the presence of sulphate. Breakthrough experiments and modeling Abstract: This report deals with the application of ion exchange columns to the treatment of groundwater contaminated by high concentrations of arsenic in the presence of sulphates. Two different process layouts were tested, based on the use of a single column and of two-in-series columns, respectively. Several breakthrough tests were performed, where the effect of the operating parameters, as the influent flow rate, the packed bed height and the feed water composition, were investigated. The collected data were described using three different modeling approaches, based on the Bohart-Adams, Yan and Thomas models, respectively. These models were all found to describe the experimental data with a quite good agreement (based on the R super(2) value). The ion exchange capacity evaluated by the models (about 3.8 mEq/g) was comparable with the value provided by the supplier (3.8 mEq/g), but higher than the value determined through batch tests of a previous study by the same authors. The models were then successfully applied to describe the breakthrough behaviour of the two in-series column plant using a real feed contaminated by high arsenic concentrations in the presence of sulphate.",
Arsenic,1508514,"Effect of carbon sources and of sulfate on microbial arsenic mobilization in sediments of West Bengal, India Abstract: Arsenic (As) dissolution from sediments into groundwater in the Bengal Delta/West India was investigated. Two experimental sites were choosen with contrasting As concentrations in shallow groundwater. Apparently patches of high-As and low-As sediments occured in close neigbourhood. A fast As mobilization with lactate or ethanol as carbon sources and sulfate as an electron acceptor and a possible influence of indigenous flora because of higher As amounts and an increasing total cell count was observed over a peroid of 110 days. Sucrose was a less suitable carbon source. Inoculation of an arsenate-reducing Pseudomonas putida WB, that was isolated from the sediments did not improve arsenic mobilization. Maximal arsenic concentrations up to 160?g/l were leached out from sediment columns with lactate or ethanol+sulfate in the water at natural groundwater flow, but the majority of the As remained in the sandy sediments. Some correlation of arsenic with Fe, but not with Mn dissolution seems to exist.",
Arsenic,2088497,"Differential methylation of the arsenic (III) methyltransferase promoter according to arsenic exposure Abstract: Inorganic arsenic is methylated in the body by arsenic (III) methyltransferase (AS3MT). Arsenic methylation is thought to play a role in arsenic-related epigenetic phenomena, including aberrant DNA and histone methylation. However, it is unclear whether the promoter of the AS3MT gene, which codes for AS3MT, is differentially methylated as a function of arsenic exposure. In this study, we evaluated AS3MT promoter methylation according to exposure, assessed by urinary arsenic excretion in a stratified random sample of 48 participants from the Strong Heart Study who had urine arsenic measured at baseline and DNA available from 1989 to 1991 and 1998-1999. For this study, all data are from the 1989-1991 visit. We measured AS3MT promoter methylation at its 48 CpG loci by bisulphite sequencing. We compared mean  % methylation at each CpG locus by arsenic exposure group using linear regression adjusted for study centre, age and sex. A hypomethylated region in the AS3MT promoter was associated with higher arsenic exposure. In vitro, arsenic induced AS3MT promoter hypomethylation, and it increased AS3MT expression in human peripheral blood mononuclear cells. These findings may suggest that arsenic exposure influences the epigenetic regulation of a major arsenic metabolism gene.",
Arsenic,2345796,"Speciation of metals in contaminated sediments from Oskarshamn Harbor, Oskarshamn, Sweden Abstract: Bottom sediments in coastal regions have been considered the ultimate sink for a number of contaminants, e.g., toxic metals. In this current study, speciation of metals in contaminated sediments of Oskarshamn harbor in the southeast of Sweden was performed in order to evaluate metal contents and their potential mobility and bioavailability. Sediment speciation was carried out by the sequential extraction BCR procedure for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn and the exchangeable (F1), reducible (F2), oxidizable (F3), and residual (R) fractionswere determined. The results have shown that Zn and Cd were highly associated with the exchangeable fraction (F1) with 42–58 % and 43–46 %, respectively, of their total concentrations in the mobile phase. The assessment of sediment contamination on the basis of quality guidelines established by the Swedish Environmental Protection Agency (SEPA) and the Italian Ministry of Environment (Venice protocol for dredged sediments) has shown that sediments from Oskarshamn harbor are highly contaminated with toxic metals, especially Cu, Cd, Pb, Hg, As, and Zn posing potential ecological risks. Therefore, it is of crucial importance the implementation of adequate strategies to tackle contaminated sediments in coastal regions all over the world.",
Arsenic,2149268,"A geochemistry study of arsenic speciation in overburden from Mae Moh Lignite Mine, Lampang, Thailand Abstract: The aim of this study was to investigate the geochemical characteristics of arsenic in the solid material samples of the Mae Moh Mine and also the Mae Moh power plants fly ash samples were systematically studied. Arsenic concentration in overburden, coal lignite and fly ash are variable (depending on source of solid samples). The results show that the strata of overburden, J seam of coal and fly ash are rich in arsenic and also relatively soluble from fly ash; it occurs as a surface precipitate on the ash particle. The experimental study on speciation in the strata also indicates that the arsenic speciation of Mae Moh solid samples are mainly arsenate, As (V), which are approaching exceed 80%. Arsenic content in the main of overburden is in the range of 14.3–888.8 mg/kg, which is larger than the arsenic background soil values. Solid materials polluted wastewater; the arsenic speciation was present predominantly as arsenate in the surface water of a series of Mae Moh solid materials basins.",
Arsenic,2064254,"Bioaccumulation and toxicity of arsenic in cyanobacteria cultures separated from a eutrophic reservoir Abstract: The bioaccumulation and toxicity of arsenate (arsenic (As)(V)) was studied using three cultures of cyanobacterial species-Oscillatoria tenuisa, Anabaena affinis, and Microcystis aeruginosa-that were isolated from a eutrophic reservoir. The As(V) uptake depended on the cyanobacterial species, the growth phase of the cyanobacteria, the duration of exposure, and the initial concentration of As(V). The specific growth rates of the three cultures immediately following the logarithmic phase were 0.033-0.041 L/day when the initial concentration of As(V) was 50 mg/L. These rates were 2.3-3.6 times less than those in the original culture medium without As(V). The rate of intake of As(V) in the logarithmic phase cultures greatly exceeded that in the stationary cultures. The accumulation of As(V) by the three cultures increased rapidly within 1 week from the initial value of 3.23?×?10(-2)-5.40?×?10(-2) to 5.06?×?10(-1)-6.73?×?10(-1) ng/cell in the logarithmic phase. The effective concentrations (EC50) of As(V) for inhibiting the growth of the three cyanobacterial species growth of at 72 h followed the order Oscillatoria tenuisa (3.8 mg/L)?&gt;?A. affinis (2.6 mg/L)?&gt;?M. aeruginosa (1.2 mg/L). The cyanobacterial species that was most sensitive to As(V) was M. aeruginosa. Preliminary results from SEM-map studies suggest most of the As(V) in Microcystis aeruginosa accumulated in the cytoplasm (intercellular), while in O. tenuisa and A. affinis, a large proportion of As(V) bound to the cell wall (extracellular). These differences were understood with reference to the variation among the metabolic properties and morphological characteristics of the cyanobacterial species.",
Arsenic,628078,"Protection against arsenic trioxide-induced autophagic cell death in U118 human glioma cells by use of lipoic acid Abstract: Arsenic is an environmental toxicant found naturally in ground water. Epidemiological studies have suggested a correlation between chronic arsenic exposure and potential brain tissue damage in clinical case and animal experiments. Lipoic acid (LA) is a thiol-compound naturally occurring in plants and animals, which is thought to be a strong antioxidant and possess neuroprotective effects. The objective of this study was to determine if the AS(2)O(3)-induced glial cell toxicity could be prevented by LA. The human malignant glioma cell (U118) was selected as a research model. By using acridine orange staining and flow cytometry analysis, we found that autophagic, but not apoptotic, cell death was significantly induced by AS(2)O(3) in U118 cells, and that AS(2)O(3)-mediated autophagic cell death was nearly completely attenuated by LA. Down-regulation of p53 and Bax proteins and the up-regulation of Bcl-2 and HSP-70 proteins were observed by western blot in AS(2)O(3)-mediated autophagic cell death. Our results implied that LA completely inhibited U118 cells autophagic cell death induced by AS(2)O(3). We suggested that LA may emerge as a useful protective agent against arsenic-induced glial cell toxicity and reversing arsenic-induced damage in human brain.",
Arsenic,1030502,"Metallurgy, environmental pollution and the decline of Etruscan civilisation Abstract: <strong>BACKGROUND, AIM AND SCOPE: </strong>The Etruscans were justifiably famous in antiquity for their advanced metallurgy and for the rich mineral resources of their region (including La Tolfa, the Colline Metallifere, Mont'Amiata and Elba). We offer a new perspective on certain Iron Age and Archaic (ca. 1,000-480 BC: ) Etruscan industrial and habitation sites, and on the problem of heavy metal poisoning, still being investigated today, coincidentally in some of the same areas that originally saw Etruscan mines and workshops.<br /><br /><strong>MATERIALS AND METHODS: </strong>This study investigates ancient sources, including literature and excavation reports, in the light of modern studies of heavy metal poisoning on human beings, plant and animal life. Furthermore, it is the first to use non-invasive Niton X-ray fluorescence analysis of samples of Etruscan (strictly ethnically Faliscan) hair (c. 350 BCE: ).<br /><br /><strong>RESULTS: </strong>The findings show the strong likelihood of heavy metal poisoning in areas of Etruscan metallurgical activity with the effects of this being responsible for or contributing to the abandonment of a number of these sites around the 6th century BC: . No thoroughly satisfactory explanation of this phenomenon has previously been offered. However, findings suggest that Faliscan women, represented by sample CG 2004-6-2, were not exposed to high levels of arsenic in life, which is not perhaps surprising for an urban aristocratic woman of the mid-4th century BC: .<br /><br /><strong>DISCUSSION: </strong>The reasons for the abandonment of several flourishing settlements are without doubt complex, and include political and social change. We suggest heavy metal contamination as an additional stimulus to the noted phenomenon of the peaceful abandonment, at the beginning, and at the end of the 6th century BC: , of sites in southern and northern Etruria such as Marsiliana d'Albegna (late 7th c.), Lago dell'Accesa, Acquarossa and Poggio Civitate-Murlo (late 6th c.).<br /><br /><strong>CONCLUSIONS: </strong>While the historical truth of the demise of Etruscan civilisation is much more complex, an interim set of related events, the desertion of several important settlements during and at the end of the Archaic period, might actually have been stimulated by the consequences of industrial pollution and arsenic poisoning.<br /><br /><strong>RECOMMENDATIONS AND PERSPECTIVES: </strong>We call for archaeologists and curators to test any available human and animal remains in their museums and collections for evidence of heavy metal poisoning, taking due caution and consideration of course to the relevance of the aristocracy, and urge the application of analytical techniques developed in response to this serious modern problem, to provide additional insights into the ancient situation.",
Arsenic,2347561,"Application of colloidal gas aphron suspensions produced from Sapindus mukorossi for arsenic removal from contaminated soil Abstract: Colloidal gas aphron dispersions (CGAs) can be described as a system of microbubbles suspended homogenously in a liquid matrix. This work examines the performance of CGAs in comparison to surfactant solutions for washing low levels of arsenic from an iron rich soil. Sodium Dodecyl Sulfate (SDS) and saponin, a biodegradable surfactant, obtained from Sapindus mukorossi or soapnut fruit were used for generating CGAs and solutions for soil washing. Column washing experiments were performed in down-flow and up flow modes at a soil pH of 5 and 6 using varying concentration of SDS and soapnut solutions as well as CGAs. Soapnut CGAs removed more than 70% arsenic while SDS CGAs removed up to 55% arsenic from the soil columns in the soil pH range of 5-6. CGAs and solutions showed comparable performances in all the cases. CGAs were more economical since it contains 35% of air by volume, thereby requiring less surfactant. Micellar solubilization and low pH of soapnut facilitated arsenic desorption from soil column. FT-IR analysis of effluent suggested that soapnut solution did not interact chemically with arsenic thereby facilitating the recovery of soapnut solution by precipitating the arsenic. Damage to soil was minimal arsenic confirmed by metal dissolution from soil surface and SEM micrograph.",
Arsenic,1508516,"A novel arsenic removal process for water using cupric oxide nanoparticles Abstract: Recent studies suggest that the cupric oxide (CuO) nanoparticles effectively adsorb aqueous arsenic species under a wide range of water chemistries. However, to develop CuO nanotechnology to a field application level, further studies are necessary. Batch adsorption kinetic experiments were conducted to determine the time course of uptake of arsenic by CuO nanoparticles. A reactor with CuO nanoparticles was developed to conduct continuous flow-through experiments to filter arsenic from groundwater samples. Groundwater samples spiked with 100?g/L of arsenic were passed through (1L/h) the flow-through reactor. Samples from the flow-through reactor were collected at a regular interval and analyzed for arsenic and other chemical components (e.g., pH, major and trace elements). The CuO nanoparticles adsorbed with arsenic were regenerated with a sodium hydroxide (NaOH) solution and tested again in the flow-through reactor. Three natural groundwater samples with above 10?g/L of arsenic were also tested with the flow-through reactor. The arsenic adsorption process by CuO nanoparticles was kinetically rapid and followed the pseudo-second-order rate. The continuous flow-through reactor with CuO nanoparticles was effective in filtering arsenic from spiked or natural groundwater. The regenerated CuO nanoparticles were also effective in filtering arsenic from groundwater. Arsenic mass balance data from regeneration studies suggested that 99% of input arsenic concentration was recovered. The CuO nanoparticle treatment did not show any discernible effects on the chemical quality of groundwater samples. Results of this study suggest that CuO nanoparticles show potential for developing a simple process for field applications to remove arsenic from water.",
Arsenic,1936158,Effect of Iron (Fe2+) Concentration in Soil on Arsenic Uptake in Rice Plant (Oryza sativa L.) when Grown with Arsenate [As(V)] and Dimethylarsinate (DMA) Abstract: ,
Arsenic,1327354,"Novel signaling stimulated by arsenite increases cholesterol metabolism through increases in unphosphorylated steroidogenic acute regulatory (StAR) protein Abstract: Cholesterol metabolism to pregnenolone is dependent on the steroidogenic acute regulatory protein (StAR), which activates mitochondrial transfer of cholesterol to cytochrome CYP450scc. In mouse Y-1 adrenal cells and testis MA10 cells stimulation by 8-Bromo-cAMP (Br-cAMP) is augmented by a novel signaling initiated by low concentrations of arsenite (3-20 microM) and anisomycin (0.2 microM), a more selective stress agent. Each elevated StAR mRNA (three-fold after 6 h treatment) even with simultaneous stimulation by Br-cAMP. Arsenite produced parallel increases in StAR protein expression and cholesterol metabolism, but not for P450scc-mediated metabolism of 20alpha-hydroxycholesterol. Although arsenite and anisomycin each stimulated the phosphorylation of p38, the p38 inhibitor SB203580 (SB) produced additive increases in StAR expression. Cholesterol metabolism increased in parallel but without the increased StAR protein phosphorylation produced by Br-cAMP. Arsenite and anisomycin each elevated StAR mRNA but preferentially increased the 3.5 kb form relative to the 1.6 kb form. Arsenite and anisomycin each enhanced the stability of the more labile 3.5 kb mRNA which contains AU-rich elements that control mRNA stability. Although there were increases in both forms of StAR mRNA, arsenite did not stimulate a StAR promoter-reporter that exhibited a typical three-fold response to Br-cAMP. Arsenite and anisomycin may therefore activate a novel SB-independent MAP kinase which in part increases StAR expression through stabilizing the 3.5 kb mRNA but which may also activate a mechanism that by-passes transcription factors detected by the reporter. SB stimulation, which was completely blocked by a MEK inhibitor, was also selective towards the 3.5 kb StAR mRNA suggesting a second pathway for mRNA stabilization. These activations contrast with inhibition of StAR expression by arsenite at higher concentrations or longer incubation times.",
Arsenic,1381845,"Causal inference in environmental epidemiology: The role of implicit values Abstract: The current epistemologic debate in epidemiology has underlined the relevance of subjective judgment in the production and evaluation of epidemiologic evidence. The definition of criteria aimed at evaluating causal links requires the adoption of judgment, values and extra-scientific considerations, such as the inclusion of a precautionary principle. The purpose of the present analysis is to examine the influence of moral principles in the process of evaluating scientific data relevant to human health. Two case studies are discussed. The first one deals with the carcinogenic risk associated with occupational exposure to non-arsenical insecticides; the second one deals with the association between urban air pollution, mortality and asthmatic attacks.",
Arsenic,2337163,"EFFECT OF ARSENIC ON GERMINATION OF ISATIS CAPPADOCICA DESV., A NEWLY DISCOVERED ARSENIC HYPERACCUMULATOR Abstract: Isatis cappadocica Desv. is a newly found As-hyperaccumulator showing very high remediation efficiency in polluted soils. We studied the effects of arsenic at 0-1400 mu M concentrations on seed germination, relative root length, relative shoot height, and root and shoot biomass in young seedlings of I. cappadocica. The seeds were from Iranian arsenic-contaminated mine spoils and from a non-contaminated population. The control for reference was brassica (Descurenia sofia). Germination decreased significantly versus the control with increasing arsenic concentrations. The response to arsenic exposure differed between the I. cappadocica populations and D. sofia. I. cappadocica from mine spoil seeds showed strong resistance to the highest As concentration, with no adverse effects until the 1000 mu M dose. Germination from non-mine seeds of I. cappadocica decreased to 89.6% at 1400 mu M As. D. sofia germination was completely inhibited at 400 mu M As. Relative root length (RRL) and relative shoot height (RSH) decreased with increasing As concentration. Overall, RRL correlated with RSH. Shoot height and root length were more sensitive to arsenic than other endpoints, and might be used as arsenic toxicity indicators. I. cappadocica showed more As tolerance than the reference brassica.",
Arsenic,1019093,"Urinary porphyrins in patients with endemic chronic arsenic poisoning caused by burning coal in China Abstract: <strong>OBJECTIVE: </strong>To evaluate the effect of arsenic (As) on the porphyrin biosynthetic pathway, urine samples from patients with endemic chronic arsenic poisoning were examined.<br /><br /><strong>SUBJECTS AND METHODS: </strong>The subjects were 16 patients, who had been exposed to As from burning coal for 8 to 25 years, and 16 controls living in the same region in Guizhou Province in southwest China. Concentrations of urinary As, porphyrins and ALA were determined by induced coupled plasma mass spectrometry (ICP-MS), high performance liquid chromatography (HPLC) with a reversed-phase column and fluorescence detector, and colorimetric spectrophotometry, respectively.<br /><br /><strong>RESULTS: </strong>Concentrations of As in patients and controls, 184.40±200.04 and 86.82±64.20? g/g creatinine (mean ±SD) respectively, were significantly different (p&lt;0.05). The concentrations of various kinds of urinary porphyrins, including isomers I and III of coproporphyrin and pentacarboxylporphyrin, were determined. Positive correlations were observed between As and porphyrins (e.g. total porphyrins, hexacarboxylporphyrin and coproporphyrin III) or between As and ALA in male and female patients. However, porphyrin and ALA concentrations were not significantly different between the patients and the controls. Urinary porphyrin concentrations in females were higher than those in males.<br /><br /><strong>CONCLUSION: </strong>Exposure to As from burning coal may influence porphyrin biosynthesis.",
Arsenic,1508703,"The mineral tooeleite Fe(6)(AsO(3))(4)SO(4)(OH)(4)?4H(2)O - An infrared and Raman spectroscopic study-environmental implications for arsenic remediation Abstract: The mineral tooeleite Fe(6)(AsO(3))(4)SO(4)(OH)(4)?4H(2)O is secondary ferric arsenite sulphate mineral which has environmental significance for arsenic remediation because of its high stability in the regolith. The mineral has been studied by X-ray diffraction (XRD), infrared (IR) and Raman spectroscopy. The XRD result indicates tooeleite can form more crystalline solids in an acid environment than in an alkaline environment. Infrared spectroscopy identifies moderately intense band at 773cm(-1) assigned to AsO(3)(3-) symmetric stretching vibration. Raman spectroscopy identifies three bands at 803, 758 and 661cm(-1) assigned to the symmetric and antisymmetric stretching vibrations of AsO(3)(3-) and As-OH stretching vibration respectively. In addition, the infrared bands observed at 1116, 1040, 1090, 981 and 616cm(-1), are assigned to the ?(3), ?(1) and ?(4) modes of SO(4)(2-). The same bands are observed at 1287, 1085, 983 and 604cm(-1) in the Raman spectrum. As(3d) band at binding energy of 44.05eV in XPS confirms arsenic valence of tooeleite is +3. These characteristic bands in the IR and Raman spectra provide useful basis for identifying the mineral tooeleite.",
Arsenic,1379313,"Effects of Metal Ions and Sulfhydryl Inhibitors on Glucose Metabolism by Adipose Tissue Abstract: The effect of divalent metal ions and sulfhydryl compounds on glucose (50997) metabolism by rat adipose tissue was studied in-vitro. The epididymal fat pad was removed from Holtzman-rats and cut into six pieces. The fat pieces were placed in a buffered incubation medium containing carbon-14 labelled glucose. One piece was placed in the buffer medium alone, and one was incubated with 500 microunits of insulin per milliliter. The remaining pieces were incubated with various concentrations (from 0.1 moles (m) to 0.0001m) of the divalent ions of cobalt (7440484) (Co), nickel (7440020) (Ni), zinc (7440666) (Zn), and the trivalent-chromium (7440473) (Cr) ion, or the sulfhydryl inhibitors cadmium (7440439) (Cd), arsenite (15502746), p-hydroxymercuribenzoate (1126483) (PHMB), and N-ethylmalcimide (128530) (NEM). After incubation, evolved carbon-dioxide (124389) was measured. Fat pad pieces were weighed, micromoles of glucose oxidized per gram fat tissue were calculated, lipids were extracted, and their radioactivity determined. The addition of insulin to the medium enhanced the metabolism of glucose by the epididymal fat pad fivefold. Co, Ni, Cd, and Zn ions stimulated glucose oxidation. These agents also stimulated the conversion of glucose into lipids. Ni and Co ions increased glucose oxidation in proportion to their concentration, while the opposite effect was seen with Zn and Cd. Trivalent-Cr did not affect glucose metabolism. PHMB increased glucose oxidation 4 fold at a concentration of 0.001m, but inhibited it at greater concentrations. Cd significantly increased glucose oxidation at a concentration of 0.10m, but its effect was lessened at lower concentrations; arsenite acted similarly. NEM inhibited glucose oxidation in proportion to its concentration. The authors conclude that certain divalent metals and some sulfhydryl inhibitors stimulate glucose oxidation by the epididymal fat pad. Cobalt and nickel may influence glucose transport into the adipose cell as insulin does. The various sulfhydryl inhibitors differ in their sites of action. NEM may act only at the cell surface, while PHMB may block specific intracellular reactions as well.",
Arsenic,710844,"Arsenic upregulates MMP-9 and inhibits wound repair in human airway epithelial cells Abstract: As part of the innate immune defense, the polarized conducting lung epithelium acts as a barrier to keep particulates carried in respiration from underlying tissue. Arsenic is a metalloid toxicant that can affect the lung via inhalation or ingestion. We have recently shown that chronic exposure of mice or humans to arsenic (10-50 ppb) in drinking water alters bronchiolar lavage or sputum proteins consistent with reduced epithelial cell migration and wound repair in the airway. In this report, we used an in vitro model to examine effects of acute exposure of arsenic (15-290 ppb) on conducting airway lung epithelium. We found that arsenic at concentrations as low as 30 ppb inhibits reformation of the epithelial monolayer following scrape wounds of monolayer cultures. In an effort to understand functional contributions to epithelial wound repair altered by arsenic, we showed that acute arsenic exposure increases activity and expression of matrix metalloproteinase (MMP)-9, an important protease in lung function. Furthermore, inhibition of MMP-9 in arsenic-treated cells improved wound repair. We propose that arsenic in the airway can alter the airway epithelial barrier by restricting proper wound repair in part through the upregulation of MMP-9 by lung epithelial cells.",
Arsenic,1358218,"Occupational and non-occupational scrotal cancer In Sweden, 1958-1970 Abstract: Occupational scrotal cancer in Swedish workers was investigated. Hospital records for all reported cases of scrotal cancer from 1958 to 1970 were examined. Histological diagnosis in all cases was squamous cell carcinoma. A detailed occupational history was obtained for each case. Etiological factors evaluated included exposure to coal, tar and soot, pitch, creosote (8021394), anthracene (120127), oil and wax, lignite (8002537) oil and wax, petroleum (8002059) oil, tar oils, asphalt, wax, carbon-black (1333864) and carbon, hydrogenated coal-oil and tar, and arsenic (7440382). A total of 34 scrotal squamous cell carcinomas was reported during the 13 year period. No rise in incidence was recorded during the latter part of the period. The highest incidence occurred between ages 60 and 69. As automatic lathe operators, seven patients had been subjected to lengthy exposure to oil and had contaminated scrotal regions. Six patients had had hand contact with motor oils. One of the six cases had concurrent psoriasis. A third group of 21 patients reported no exposure to oil. Of the 34 cases, 16 (47 percent) died during the observation period. The majority (about 80 percent) of scrotal squamous cell carcinoma cases were nonoccupational. Lung cancer developed in one of seven subjects who had lengthy exposure to oil.",
Arsenic,2345685,"A prospective observational study of the prevalence and risk factors for colonization by antibiotic resistant bacteria in patients at admission to hospital in Singapore Abstract: <strong>BACKGROUND: </strong>Drug resistant organisms pose an increasing threat to the successful treatment of common infections. Understanding colonization patterns of these bacteria is important for effective antibiotic treatment and infection control guidelines.<br /><br /><strong>METHODS: </strong>A prospective observational study was performed to determine the prevalence of colonization with extended-spectrum ?-lactamase-producing Enterobacteriaceae (ESBL-E), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) among patients admitted via the emergency department to a public tertiary hospital in Singapore. Anterior nares, groin, axillary and rectal swabs were collected at admission and cultured using standard bacteriological techniques. Clinical data including healthcare contact within the past 12 months and recent antibiotic use was collected and analyzed using a logistic regression model.<br /><br /><strong>RESULTS: </strong>1006 patients were screened. 124 (12.4%) were colonized by ESBL-E, 18 (1.8%) by MRSA while no VRE was detected. Antibiotic use within the past month was the only significant predictor for ESBL-E colonization in the regression model, with an adjusted odds ratio (AOR) of 2.58 (1.04 to 6.42). In participants recently prescribed antibiotics and hospitalized in the previous 3 months, 29.4% were colonized by ESBL-E. This represented 20.2% of the total ESBL-E burden, and ESBL-E was also detected in 6.3% of participants with no healthcare contact. Hospitalization and outpatient hospital visits predicted MRSA colonization in the univariate analysis. Neither was statistically significant in the logistic regression model, with AORs for MRSA colonization following hospitalization in the past 3 and 12 months of 3.81 [95% CI 0.84-17.28] and 3.48 [0.64-18.92] respectively.<br /><br /><strong>CONCLUSION: </strong>A high prevalence of colonization with ESBL-E was evident among patients at admission, even in the absence of recent antibiotic use or contact with healthcare.",
Arsenic,1026099,"Expression and activity of arsenic methyltransferase Cyt19 in rat tissues Abstract: Arsenic has been reportedly metabolized by the repetitive reduction and methylation, and is excreted mainly in urine as methylated arsenicals such as monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)). Although it has been demonstrated that the methylation of arsenic is catalyzed by arsenic methyltransferase, Cyt19, very little is known about the characteristics of this enzyme. We investigated mRNA and protein levels of Cyt19 and the enzyme activity of Cyt19 in rat tissues by Northern and Western blottings and high-performance liquid chromatography-inductively coupled argon plasma mass spectrometry (HPLC-ICP MS). Both mRNA and protein levels of the liver were higher than those of other tissues. An intermediate expression of Cyt19 mRNA was observed in the heart and testis. Methylated arsenicals were found to be produced by the liver cytosol using the current HPLC-ICP MS method.",
Arsenic,1337725,"Inhibition of hepatocyte nuclear factor 1 and 4 alpha (HNF1? and HNF4?) as a mechanism of arsenic carcinogenesis Abstract: Inorganic arsenic (i-As) is a naturally occurring toxic metalloid affecting millions of people worldwide. It is known to be carcinogen, liver being a potential target, and related to the prevalence of diabetes in arseniasis-endemic areas. Hepatocyte nuclear factor 1 and 4 alpha (HNF1? and HNF4?) are key members of a transcriptional network essential for normal liver architecture. Changes in HNF1? and HNF4? expression are clearly associated with the development of liver malignancies and diabetes in humans. In this work, hepatic HepG2 cells and golden Syrian hamsters were exposed to sub-toxic, environmentally relevant doses of sodium arsenite (SA; up to 10 ?M in vitro, 15 mg/L in vivo) in order to evaluate whether arsenic is able to compromise the expression of hepatocyte nuclear factors. Also, liver histopathological examination was carried out, and several markers of hepatocyte differentiation and glucose metabolism status were determined as a measure of i-As-induced effects. Results show a consistent down-regulation of HNF1? and HNF4? under a scenario of exposure where HepG2 cells (1) gained resistance to arsenic-induced toxicity/apoptosis, (2) attained loss of tissue-specific features (as shown by the observed down-regulation of ALDOB, PEPCK and CYP1A2, triggering of the epithelial-to-mesenchymal transition program and the hypersecretion of matrix metalloproteinase-2 and 9), (3) failed to maintain balanced expression of the &quot;stemness&quot; genes C-MYC, OCT3/4, LIN28 and NOTCH2 and (4) showed glucose metabolism impairment. We conclude that the i-As-induced down-regulation of HNF1? and HNF4? under chronic settings may play a central role in the features of disease and cancer observed both in vivo and in vitro.",
Arsenic,451062,"Chronic renal failure among farm families in cascade irrigation systems in Sri Lanka associated with elevated dietary cadmium levels in rice and freshwater fish (Tilapia) Abstract: Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 mu g/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 mu g/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 mu g/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 mu g Cd/g creatinine and in asymptomatic persons UCd was 11.62 mu g Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years.",
Arsenic,1519065,"Optimization of bioleaching conditions for metal removal from CCA-treated wood by using an unknown Polyporales sp. KUC8959 Abstract: The purpose of this study was to investigate the effect of extraction conditions (i.e., culture filtrate concentration, extraction temperature, and extraction time) on the removal of metals from chromated copper arsenate (CCA)-treated wood particles by using an unknown Polyporales sp. KUC8959. As the first research, a 20-run central composite design using response surface methodology was applied to optimize the system and construct the models, which predicted metal removal by bioleaching. The coefficients of determination of fitted models were 0.874-0.989, which indicated that the models can predict the metal removal yield accurately under various conditions. The Cu removal model suggested that the following conditions, culture filtrate concentration of 45.8%, extraction temperature of 34.2 °C, and extraction time of 20.6 h, were required for maximal removal of Cu (82.1%). The model predicted that extraction conditions of increased severity would result in complete removal of Cr and As from CCA-treated wood particles. In order to confirm actual metals removal efficiency, metals extraction was subsequently conducted under optimal bioleaching condition evaluated in this study. By applying the model, we demonstrated 83.9% Cu, 96.0% Cr, and 99.3% As removal from treated wood particles.",
Arsenic,1704100,"Interaction of Magnesium-Iron-Carbonic-Layered Double Hydroxides with As(III) Abstract: Hydrotalcite-like compounds (HTlcs) are of potential environmental significance due to a reactive interlayer that may act as a natural sink during precipitation under ambient conditions or after interaction with contaminants. This study focused on the partitioning of As(III) on MgFeCO3-type HTlcs, in consideration of the predominance of both Mg2+ and Fe3+ in CO2-equilibrated natural settings. Sequestration of As(III) during HTlc precipitation was several orders of magnitude greater compared to interaction with pre-existing HTlc precipitates. This is attributed to the participation of As(III)oxyanion species in the maintenance of surface charge neutrality during active precipitation. The degree of crystallinity, crystallite size, and interlayer thickness of the Mg-FeCO3-type HTlc all decreased slightly upon As(III) incorporation; metal-metal coordination was largely unaffected. Ambient interaction of the HTlc with As(III) caused CO32- incorporation into the interlayer from atmospheric CO2 even in the absence of a dissolved CO32- source. The interlayer occupancy of entrapped As(III) constituted a minor fraction of the total mass sequestered, resulting in a low intensity Raman spectral vibration at similar to 810 cm(-1). Minimal changes in the thermal stability due to As(III) incorporation were measured. However, total mass loss occurred through multiple stages in As(III)-incorporated HTlcs compared to pure HTlc due to excess H2O absorption onto the surface and structural incorporation of CO32- .",
Arsenic,628468,"Impact of arsenite and its methylated metabolites on PARP-1 activity, PARP-1 gene expression and poly(ADP-ribosyl)ation in cultured human cells Abstract: The underlying mechanisms of arsenic carcinogenicity are still not fully understood. Mechanisms currently discussed include the induction of oxidative DNA damage and the interference with DNA repair pathways. Still unclear is the role of biomethylation, which has long been considered to be one major detoxification process. Methylated arsenicals have recently been shown to interfere with DNA repair in cellular and subcellular systems, but up to now no DNA repair protein has been identified being particular sensitive towards methylated arsenicals in cultured cells. Here we report that the trivalent methylated metabolites MMA(III) and DMA(III) inhibit poly(ADP-ribosyl)ation in cultured human HeLa S3 cells at concentrations as low as 1nM, thereby showing for the first time an inactivation of an enzymatic reaction related to DNA repair by the trivalent methylated arsenicals at very low environmentally relevant concentrations. In contrast the pentavalent metabolites MMA(V) and DMA(V) showed no such effects up to high micromolar concentrations. All investigated arsenicals did not alter gene expression of PARP-1. However, all trivalent arsenicals were able to inhibit the activity of isolated PARP-1, indicating that the observed decrease in poly(ADP-ribosyl)ation in cultures human cells, predominantly mediated by PARP-1, is likely due to changes in the activity of PARP-1. Since poly(ADP-ribosyl)ation plays a major role in DNA repair, cell cycle control and thus in the maintenance of genomic stability, these findings could in part explain DNA repair inhibition and the genotoxic and carcinogenic effects of arsenic.",
Arsenic,89886,"Mortality in a cohort of Russian fertilizer workers Abstract: OBJECTIVES. The study evaluated the mortality of workers exposed to precursors of N-nitroso compounds in a Russian fertilizer plant. METHODS. Workers employed at least two years between 1945 and 1985 in production departments or other services were included in the cohort, which comprised 2039 men and 2957 women followed from 1965 to 1990. The standardized mortality ratios (SMR) were calculated using cause-specific death rates for the Moscow region as reference. An internal comparison was carried out using Poisson regression modeling. Exposure to arsenic, nitrogen oxides, and sulfur dioxide was estimated from an industrial hygiene survey. RESULTS. The production and other workers had no excess of mortality from all causes or all neoplasms. However the male production workers had excess mortality from all cancers combined (SMR 143) and lung cancer (SMR 186) after a latency period of > or = 20 years. Men with the highest exposure to nitrogen oxides had a twofold increase in mortality from stomach cancer, with a marginally significant increasing trend between stomach cancer and cumulative exposure to nitrogen oxides for both genders. Excess mortality from all cancers and stomach cancer was found for the worker with the highest average exposure to arsenic, and excess lung cancer mortality could be attributed to exposure to arsenic. CONCLUSIONS. The investigation showed a weak association between employment in a fertilizer production plant and increased mortality from cancer. The results somewhat support the hypothesis that occupational exposure to precursors of N-nitroso compounds increases the risk of stomach cancer mortality, as does exposure to arsenic.",
Arsenic,1024588,"Noninfectious dermatological diseases associated with chronic exposure to mine tailings in a Peruvian district Abstract: <strong>BACKGROUND: </strong>Mine tailings are metallic wastes which are deposited in the environment due to mining activity. Long-term exposure to these metals is harmful to human health.<br /><br /><strong>OBJECTIVE: </strong>To determine if chronic exposure to mine tailings constitutes a risk factor for the development of dermatological diseases in the district of San Mateo de Huanchor (Lima, Peru).<br /><br /><strong>METHODS: </strong>An observational case-control study was carried out in the communities of Mayoc, Daza and Tamboraque (exposed to mine tailings, case group) located in the district of San Mateo de Huanchor, and also in the communities of Choccna and Caruya (not exposed to mine tailings, control group) located in the same district. Out of 230 adults, 121 were exposed and 109 were not exposed to mine tailings and out of 135 children, 71 were exposed and 64 were not exposed to mine tailings.<br /><br /><strong>RESULTS: </strong>In the adult group, 71% of the exposed cases had some noninfectious dermatological disease while in the nonexposed group the frequency was 34% [P &lt; 0.001; odds ratio (OR) 5.40; 95% confidence interval (CI) 3.02-9.68]. A statistically significant difference between groups was found for arsenical dermatitis, nonpruritic papulovesicular eruption, atopic dermatitis, contact dermatitis, seborrhoeic dermatitis and xerosis. In the paediatric population, 71 exposed and 64 nonexposed children were evaluated. Sixty-nine per cent of the exposed group had some noninfectious dermatological disease vs. 30% in the nonexposed group (P &lt; 0.001; OR 6.00; 95% CI 2.71-13.31). A statistically significant difference between groups was found for xerosis and atopic dermatitis.<br /><br /><strong>CONCLUSION: </strong>Chronic exposure to mine tailings represents a risk factor for development of noninfectious dermatological diseases in both adults and children.",
Arsenic,1352799,Arsenic exposure and histological alterations of pancreas Abstract: ,
Arsenic,1579405,"Arsenic-induced oxidative stress and antioxidant defense system of Pisum sativum and Pennisetum typhoides: A comparative study Abstract: A study of arsenic–induced oxidative damage and response of antioxidant enzymes in the aerial parts of Pennisetum typhoides and Pisum sativum was carried out. Seedlings of test plants were grown hydroponically in Hoagland nutrient solution and enriched with different concentrations of arsenic (0, 10, 25, 50, 100 and 200 ?M) for 10 days. Time course study was carried out in test plants exposed to sublethal concentration of Arsenic (50 ?M). This work aims to carry out a comparative study between the two test plants based on the above parameters. Arsenic accumulation increased with an increase in arsenic concentration in the growth medium, the most being found in P. typhoides showing less toxicity symptoms than P. sativum. In addition, plant growth inhibition was higher in P. sativum than P. typhoides exposed to increasing concentration of arsenic. Lipid peroxidation and H2O2 were found to be lowest in P. typhoides which correspond with its observed tolerance to arsenic. Also, the amount of thiol content and photosynthetic pigments was decreased with increasing concentration of Arsenic. Both test plants responded differentially to arsenic exposure in terms of antioxidative defence. Higher levels of superoxide dismutase, catalase and ascorbate peroxidase were observed in P. typhoides than in P. sativum, showing their active involvement in the arsenic detoxification mechanism. Result shows that due to strong enzymatic antioxidant defense system P. typhoides is comparatively arsenic tolerant than P. sativum.",
Arsenic,1597433,"Oxidative stress induced by arsenopyrite and the role of desferrioxamine-B as radical scavenger Abstract: Arsenopyrite (FeAsS) is one of the earth's primary mineral sources of As, yet its effects on cell damage remain largely unknown. This paper addresses the question whether FeAsS induces lipid peroxidation (LP), a major indicator of oxidative stress. Screening and monitoring of LP was conducted using Thiobarbituric Acid Reactive Substances (TBARSs) assay. The lipid source was supernatant of rat brain homogenates. The formation of TBARS by FeAsS was rapid and took place just after 10 min. Maximum TBARS levels (ca. 14 nmol TBARS per mg of protein) were observed after 1h and remained constant thereafter. Suspension fraction separations showed that dissolved and structural components contributed to LP. The formation of TBARS by soluble As, As(III) or As(V), compared to basal levels. The initiation of LP by FeAsS was consistent with a mechanism initiated by the Fe(3+)/O(2)(-) redox system, and differed initiated by Fe(2+)/O(2). The effectiveness of FeAsS and FeSO(4) as inducer compared, and surpassed that of AAPH. On the other hand, the initiation of LP by FeAsS is consistent with a mechanism initiated by perferryl ion and Fe(3+)/O(2)(-), and differs from the mechanism characteristic of FeSO(4) initiated by the Fe(2+)/O(2) redox system. Proposedly, FeAsS surfaces contain a mixture of Fe(3+) and Fe(2+) that, along with O(2) and O(2)(-), participate in multiple mechanisms of electron transfer. EPR determinations show decreases in DMPO-OH adduct signal in FeAsS suspensions after adding desferrioxamine-B (DFO-B), consistent with the idea that DFO-B serves as a radical scavenger.",
Arsenic,198589,"Dioxin and diabetes mellitus: an analysis of the combined NIOSH and Ranch Hand data Abstract: OBJECTIVES: To reanalyze in a similar manner the two principal studies of TCDD (tetrachlorodibenzo-p-dioxin) and diabetes in an attempt to reconcile disparate results. METHODS: Data from 990 United States Air Force veterans (Ranch Hand) and 1275 referents were reanalyzed, and a NIOSH population of 267 chemical workers and 227 referents. The Ranch Hand veterans had lower concentrations of lipid adjusted serum TCDD (median 12 parts per trillion (ppt)) than the NIOSH workers (median 75 ppt) when examined in the late 1980s. An analysis was conducted of the combined data sets, adopting a uniform approach to outcome definition, data analysis, and covariate control. RESULTS: The combined exposed groups did not differ markedly from the combined non-exposed groups for prevalence of diabetes (odds ratio (OR) 1.17, 95% confidence interval (95% CI) 0.92 to 1.48), with no evidence of heterogeneity of exposure effect between studies. Also virtually no difference was found between combined exposed and non-exposed groups in mean fasting serum glucose (difference in log serum glucose 0.002, 95% CI -0.006 to 0.010), and there was little evidence in either study of a dose-response trend for fasting serum glucose. An increasing trend was found (p=0.0001) in prevalence of diabetes with increased TCDD (at the time of examination or at time of last exposure) among the Ranch Hand population, with excess risk largely confined to the highest 8% of the exposed group (>78 ppt serum TCDD), which had an OR of 3.21 (95% CI 1.81 to 5.72) versus those with <10 ppt TCDD. However, no such positive dose-response was found in the NIOSH population. CONCLUSIONS: There was little overall evidence that the exposed workers were at higher risk than the non-exposed workers of diabetes or abnormal fasting glucose. However, the Ranch Hand subjects showed a positive dose-response for diabetes, whereas the more highly exposed NIOSH subjects did not. The reason for the difference in diabetes dose-response trends between the two studies is unknown.",
Arsenic,2064280,"Arsenic Speciation in Rice Cereals for Infants Abstract: The aim of this study was to conduct a survey of arsenic (As) content in rice cereals for infants. The analysis was based on the FDA Elemental Analysis Manual (EAM 4.11). An Inductively Coupled Plasma Mass Spectrometer (ICP-MS) was used to determine total As. The ICP-MS coupled to a High Performance Liquid Chromatograph (HPLC) was used to determine total As concentrations and to perform As speciation, due to the different toxicity of the chemical forms of arsenic. The total and speciated arsenic was determined in 31 different infant rice cereals sold in US supermarkets. The inorganic As (arsenite As(III) and arsenate As(V)) concentrations ranged between 55.5 ± 1.3 µg/kg and 158.0 ± 6.0 µg/kg. The average total Arsenic and iAs concentrations in baby rice cereal were 174.4 and 101.4 µg/kg, respectively. There was no substantial difference in iAs levels between organic and conventional rice cereals. The mixed grain rice cereal contained the least total (105 µg/kg) and inorganic arsenics (63 µg/kg). The major detected organoarsenical specie was dimethylarsinic acid (DMA). Monomethylarsonic acid (MMA) was not detected or only trace levels were found. Spiked sample % recoveries for iAs, DMA and MMA ranged from a low of 97.3% for iAs to a high of 115.0% for DMA. Results for speciated and total As in the National Institute of Standards and Technology standard reference material - rice flour (NIST SRM 1568) were in good agreement with certified values. In the NIST SRM 1568 sample (n=5) repeatability (%RSD) was 2.8% for iAs, 1.7% for DMA and total arsenic by As speciation method and 5.3% for the total arsenic by As total method. The average % mass balance was 99.9% ± 6.3 for the NIST SRM 1568 sample. This study provides new and much needed information on arsenic levels in rice and rice based infant cereals.",
Arsenic,628580,"Effect of plasma homocysteine level and urinary monomethylarsonic acid on the risk of arsenic-associated carotid atherosclerosis Abstract: Arsenic-contaminated well water has been shown to increase the risk of atherosclerosis. Because of involving S-adenosylmethionine, homocysteine may modify the risk by interfering with the biomethylation of ingested arsenic. In this study, we assessed the effect of plasma homocysteine level and urinary monomethylarsonic acid (MMA(V)) on the risk of atherosclerosis associated with arsenic. In total, 163 patients with carotid atherosclerosis and 163 controls were studied. Lifetime cumulative arsenic exposure from well water for study subjects was measured as index of arsenic exposure. Homocysteine level was determined by high-performance liquid chromatography (HPLC). Proportion of MMA(V) (MMA%) was calculated by dividing with total arsenic species in urine, including arsenite, arsenate, MMA(V), and dimethylarsinic acid (DMA(V)). Results of multiple linear regression analysis show a positive correlation of plasma homocysteine levels to the cumulative arsenic exposure after controlling for atherosclerosis status and nutritional factors (P < 0.05). This correlation, however, did not change substantially the effect of arsenic exposure on the risk of atherosclerosis as analyzed in a subsequent logistic regression model. Logistic regression analyses also show that elevated plasma homocysteine levels did not confer an independent risk for developing atherosclerosis in the study population. However, the risk of having atherosclerosis was increased to 5.4-fold (95% CI, 2.0-15.0) for the study subjects with high MMA% (> or =16.5%) and high homocysteine levels (> or =12.7 micromol/l) as compared to those with low MMA% (<9.9%) and low homocysteine levels (<12.7 micromol/l). Elevated homocysteinemia may exacerbate the formation of atherosclerosis related to arsenic exposure in individuals with high levels of MMA% in urine.",
Arsenic,536228,"Neuropsychological correlates of hair arsenic, manganese, and cadmium levels in school-age children residing near a hazardous waste site Abstract: A pilot study was conducted to explore the potential associations between hair metal levels and the neuropsychological function and behavior of school-aged children. Thirty-two children, 11-13 years old, were administered a battery of tests that assessed general intelligence, visual-motor skills, receptive language, verbal memory, nonverbal problem-solving, and behavior problems. Parents and teachers rated the children's attention, executive functions, and behavior problems. The concentrations of manganese (Mn), arsenic (As), and cadmium (Cd) were measured in hair samples provided by 31 of the children. The mean hair metal levels were: Mn, 471.5 parts per billion (ppb); As, 17.8 ppb; Cd, 57.7 ppb. Children's general intelligence scores, particularly verbal IQ scores, were significantly related, inversely, to hair Mn and As levels, as were scores on tests of memory for stories and a word list. In some cases, a significant Mn-by-As interaction was found. It appeared that it was the low scores of children for whom both Mn and As levels were above the median values in the sample that were responsible for the main effects observed for each metal. No other significant relationships were found. These results suggest the need to study further the neuropsychological correlates of developmental exposure to Mn and As, particularly as a mixture. (c) 2005 Elsevier Inc. All rights reserved.",
Arsenic,627341,"Methylarsenicals and arsinothiols are potent inhibitors of mouse liver thioredoxin reductase Abstract: Thioredoxin reductase (TR, EC 1.6.4.5) was purified 5800-fold from the livers of adult male B6C3F1 mice. The estimated molecular mass of the purified protein was about 57 kDa. The activity of the purified enzyme was monitored by the NADPH-dependent reduction of 5, 5'-dithiobis(2-nitrobenzoic acid) (DTNB); this activity was fully inhibited by 1 microM aurothioglucose. Arsenicals and arsinothiols, complexes of As(III)-containing compounds with L-cysteine or glutathione, were tested as inhibitors of the DTNB reductase activity of the purified enzyme. Pentavalent arsenicals were much less potent inhibitors than trivalent arsenicals. Among all the arsenicals, CH(3)As(III) was the most potent inhibitor of TR. CH(3)As(III) was found to be a competitive inhibitor of the reduction of DTNB (K(i) approximately 100 nM) and a noncompetitive inhibitor of the oxidation of NADPH. The inhibition of TR by CH(3)As(III) was time-dependent and could not be reversed by the addition of a dithiol-containing molecule, 2,3-dimercaptosuccinic acid, to the reaction mixture. The inhibition of TR by CH(3)As(III) required the simultaneous presence of NADPH in the reaction mixture. However, unlike other pyridine nucleotide disulfide oxidoreductases, there was no evidence that mouse liver TR was inactivated by exposure to NADPH. Treatment with CH(3)As(III) did not increase the NADPH oxidase activity of the purified enzyme. Thus, CH(3)As(III), a putative intermediate in the pathway for the biomethylation of As, is a potent and irreversible inhibitor of an enzyme involved in the response of the cell to oxidative stress.",
Arsenic,1032259,"Gallium arsenide selectively inhibits T cell proliferation and alters expression of CD25 (IL-2R/p55) Abstract: Exposure (24 hr) to a single intratracheal administration of gallium arsenide (GaAs; 200 mg/kg) has been shown to suppress antibody production as well as other T cell-mediated immunological functions. GaAs has also been shown to exert toxic effects on events occurring early in the antibody-forming cell response which may include lymphocyte activation and proliferation. Studies were undertaken to determine whether GaAs exposure resulted in the inability of T and B lymphocytes to proliferate in response to an antigenic stimulus. During the first 24 hr after in vitro immunization with sheep red blood cells, GaAs-exposed splenocytes were suppressed 51% in their ability to proliferate compared to the vehicle (0.05% Tween 80 in saline; VH) control. There was no significant difference in absolute numbers of cluster designation (CD)8+ cells between VH- and GaAs-exposed cultures. There was, however, a 50% decrease in CD4+ cells evaluated 24 hr after immunization with sheep red blood cells which persisted for the 5-day culture period. T and B cells were isolated and analyzed for proliferative capacity in response to various mitogenic stimuli. Isolated B cells exhibited no difference between VH- and GaAs-exposed cells in proliferative capacity to either lipopolysaccharide or anti-immunoglobulin plus interleukin-4. However, isolated T cells exposed to GaAs were significantly suppressed in their ability to proliferate to concanavalin A, phytohemagglutinin and anti-CD3 epsilon plus interleukin-2 when compared to VH. In addition, expression of CD25, leukocyte function antigen-1 and intercellular adhesion molecule-1 in GaAs-exposed mice were significantly below VH (36, 18 and 18%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,2064201,"A simplified analysis of dimethylarsinic acid by wavelength dispersive X-ray fluorescence spectrometry combined with a strong cation exchange disk Abstract: Dimethylarsinic acid (DMA(V)) was pre-concentrated from water samples using a strong cation exchange (SCX) disk functionalized with sulfonic groups, before being analyzed by wavelength dispersive X-ray fluorescence spectrometry (WDXRF). The adsorption of DMA(V) occurred preferentially on the surface of the SCX disk, regardless of pH levels, probably due to interactions with the sulfonic functional groups. However, no other arsenic species, such as arsenate (iAs(V)), arsenite (iAs(III)), and monomethylarsonic acid (MMA(V)), were retained. The SCX-WDXRF method produced a strongly linear calibration curve (R(2)=0.9996) with its limit of detection at 0.218?gL(-1) when a one-liter water sample was used for pre-concentration. The As intensity of the system was sensitive to the Pb content retained on the SCX disk owing to the proximity of the As-K? and Pb-L? lines. To compensate for this interference, a correction factor was developed by considering the calibration slope ratio between the X-ray intensity measured at a Bragg angle of 48.781° and the Pb content of the SCX disks. The results of spike tests for iAs(V), iAs(III), MMA(V), and DMA(V) with and without the addition of Pb in synthetic landfill leachate exhibited reasonable recoveries (i.e., 98-105%) after the spectral adjustment for the Pb interference.",
Arsenic,2278937,"Differences in phosphorus translocation contributes to differential arsenic tolerance between plants of Borreria verticillata (Rubiaceae) from mine and non-mine sites Abstract: We have identified new arsenic-tolerant plant species Borreria verticillata (Rubiaceae) that has mine and non-mine populations at a highly contaminated site (CS) and an uncontaminated site (UCS), respectively, in Brazil. Plants of B. verticillata from both sites were cultivated at different As and P concentrations. At low P concentration, CS plants showed reduced As uptake, higher P translocation to shoots, higher constitutive levels of phenolic compounds in roots, and higher tolerance to this metalloid. At the lowest P and highest As concentration, CS plants showed higher biomass. In addition, CS plants showed higher P uptake in the absence of As, suggesting that more efficient P translocation could contribute more to tolerance than decreased As uptake. In contrast, at low P concentration, UCS plants showed higher As content in shoot and root, increase in phenol levels in roots, reduction in dry biomass, and decrease of the effective efficiency of photochemical reactions and the electron transport rate. Under higher P concentrations, the decrease in As uptake was similar in both populations. The differences between the two populations with respect to As and P uptake suggest that altered kinetic properties or expression of P transporters contribute to higher As tolerance in B. verticillata from CS. As a ruderal and As-tolerant plant, B. verticillata could be successfully used for the revegetation of contaminated soils.",
Arsenic,1352443,Phototrophic Phylotypes Dominate Mesothermal Microbial Mats Associated with Hot Springs in Yellowstone National Park Abstract: ,
Arsenic,2347630,"Phytoremediation of arsenic by Trapa natans in a hydroponic system Abstract: Phytoremediation of arsenic (As) by water chestnut (Trapa natans) in a hydroponic system was studied. Plants were grown at two concentrations of arsenic, 1.28 mg/L and 10.80 mg/L, in a single metal solution. Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) confirmed highest arsenic concentration in the roots, followed by shoots and leaves. SEM-EDX also confirmed internalization of arsenic in T. natans and the damage caused due to arsenic exposure. Fourier Transform Infra Red Spectroscopy (FT-IRS) indicated that the binding characteristics of the arsenic ions involved the hydroxyl, amide, amino, and thiol groups in the biomass. Chlorophyll concentration decreased with increasing metal concentration and duration of exposure, but proline content increases with increasing concentration in the plant. Morphological changes were studied on the 3rd, 5th and 7th day. Unhealthy growth and chlorosis were found to be related with arsenic toxicity. From the above studies it is clear that T. natans can be used successfully for the removal of arsenic ions by a phytoremediation process.",
Arsenic,2064211,"Temperature-induced impacts on groundwater quality and arsenic mobility in anoxic aquifer sediments used for both drinking water and shallow geothermal energy production Abstract: Aquifers used for the production of drinking water are increasingly being used for the generation of shallow geothermal energy. This causes temperature perturbations far beyond the natural variations in aquifers and the effects of these temperature variations on groundwater quality, in particular trace elements, have not been investigated. Here, we report the results of column experiments to assess the impacts of temperature variations (5°C, 11°C, 25°C and 60°C) on groundwater quality in anoxic reactive unconsolidated sandy sediments derived from an aquifer system widely used for drinking water production in the Netherlands. Our results showed that at 5 °C no effects on water quality were observed compared to the reference of 11°C (in situ temperature). At 25°C, As concentrations were significantly increased and at 60 °C, significant increases were observed pH and DOC, P, K, Si, As, Mo, V, B, and F concentrations. These elements should therefore be considered for water quality monitoring programs of shallow geothermal energy projects. No consistent temperature effects were observed on Na, Ca, Mg, Sr, Fe, Mn, Al, Ba, Co, Cu, Ni, Pb, Zn, Eu, Ho, Sb, Sc, Yb, Ga, La, and Th concentrations, all of which were present in the sediment. The temperature-induced chemical effects were probably caused by (incongruent) dissolution of silicate minerals (K and Si), desorption from, and potentially reductive dissolution of, iron oxides (As, B, Mo, V, and possibly P and DOC), and mineralisation of sedimentary organic matter (DOC and P).",
Arsenic,1034448,"Genotoxicity testing of arsenobetaine, the predominant form of arsenic in marine fishery products Abstract: Marine fishery products may contain high levels of arsenic, mainly in the form of organic arsenic compounds. Arsenobetaine has been identified as the predominant form occurring in marine fishery products. The potential initiating and promoting capacities of this compound were therefore investigated in vitro. In the Salmonella typhimurium assay, no mutagenicity was observed in strains TA97, TA98 and TA100 without activation or after addition of a liver-enzyme fraction or gut-flora extract. The compound was also negative in the forward mutation assay of the HGPRT gene and in the test for sister chromatid exchanges in V79 Chinese hamster cells. No inhibition of metabolic co-operation between V79 Chinese hamster cells was observed at arsenobetaine concentrations up to 10 mg/ml. In addition, arsenobetaine had no synergistic or antagonistic effects on the action of the positive controls benzo[a]pyrene and tetradecanoylphorbol-13-acetate.",
Arsenic,1034325,"Effects of arsenate and ergot alkaloid compounds on prostacyclin synthesis in human umbilical endothelium Abstract: Cultured human umbilical endothelium was incubated with various concentrations of o-arsenilic acid and ergotamine tartrate respectively for 72 hr at 37 degrees C, 5% CO2/95% air in 100% humidity. At the end of incubation, medium was removed for the determination of 6-keto-PGF1 alpha concentration by RIA method. Compared to the normal controls, arsenate (0.1 to 10.0uM) showed inhibition (17 to 24%) on the PGI2 production. Ergotamine tartrate gave an activatory effect (20 to 12%) in low concentration (0.1 to 1.0uM) incubation, but had inhibitory effect (25%) on the PGI2 production in higher concentration incubation (10.0uM). These results indicate arsenate in low and high concentrations does not play an important role on prostacyclin synthesis in human umbilical endothelium. However, ergotamine tartrate at higher concentration might be a main factor for the lower prostacyclin synthesis in Blackfoot disease, an endemic disease of the peripheral vascular system found in the southwest coast of Taiwan.",
Arsenic,1030447,"Arsenic-induced oxidative cerebral disorders: protection by taurine Abstract: The present study was conducted to investigate whether the conditionally essential amino acid, taurine, could play any protective role against the potent neurotoxin arsenic (As)-induced oxidative impairment in the rat brain. Administration in the form of NaAsO(2) (at a dose of 10 mg/kg body weight for 2 days, orally), As increased the intracellular accumulation of metallic As, reactive oxygen species, and super oxide radicals. The toxin also augmented the extent of lipid peroxidation, protein carbonylation, and the levels of glutathione disulphide. Activities of the antioxidant enzymes, membrane-bound enzymes, acetylcholinesterase, and the levels of reduced glutathione, as well as total thiols, have been significantly decreased due to As exposure. Oral administration of taurine (at a dose of 100 mg/kg/body weight for 5 days) was found to be very effective in the prevention of As-induced oxidative impairment in the brain tissue of the experimental rats. To validate the experimental results, a well-known water-soluble antioxidant, vitamin C, was used as the positive control in the study. Combining all, results suggest that taurine plays a beneficial role against As-induced cerebral oxidative stress.",
Arsenic,1797766,"Exposure of Brassica juncea (L) to arsenic species in hydroponic medium: comparative analysis in accumulation and biochemical and transcriptional alterations Abstract: Arsenic (As) contamination in the environment has attracted considerable attention worldwide. The objective of the present study was to see the comparative effect of As species As(III) and As(V) on accumulation, biochemical responses, and gene expression analysis in Brassica juncea var. Pusa Jaganath (PJn). Hydroponically grown 14-day-old seedlings of B. juncea were treated with different concentrations of As(III) and As(V). Accumulation of total As increased with increasing concentration of both As species and exposure time, mainly in roots. Reduction in seed germination, root-shoot length, chlorophyll, and protein content were observed with increasing concentration and exposure time of both As species, being more in As(III)-treated leaves. PJn variety showed that antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)) and stress-related parameters (cysteine, proline, and malondialdehyde (MDA)) were stimulated and allows plant to tolerate both As species. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis in leaves showed significant changes in protein profile with more stringent effect with As(III) stress. Semiquantitative RT-PCR analysis showed regulation in expression of phytochelatin synthase (PCS), metallothionine-2 (MT-2), glutathione reductase (GR), and glutathione synthetase (GS) genes under both As(III) and As(V) stresses. Results suggested that accumulation and inhibition on physiological parameters differ according to the As species, while molecular and biochemical parameters showed a combinatorial type of tolerance mechanism against As(III) and As(V) stresses.",
Arsenic,1936118,"Arsenic and iron removal from groundwater by oxidation-coagulation at optimized pH: Laboratory and field studies Abstract: A three-step treatment process involving (i) mild alkaline pH-conditioning by NaHCO3; (ii) oxidation of arsenite and ferrous ions by KMnO4, itself precipitating as insoluble MnO2 under the pH condition; and (iii) coagulation by FeCl3 has been used for simultaneous removal of arsenic and iron ions from water. The treated water is filtered after a residence time of 1-2h. Laboratory batch experiments were performed to optimize the doses. A field trial was performed with an optimized recipe at 30 households and 5 schools at some highly arsenic affected villages in Assam, India. Simultaneous removals of arsenic from initial 0.1-0.5mg/L to about 5?g/L and iron from initial 0.3-5.0mg/L to less than 0.1mg/L have been achieved along with final pH between 7.0 and 7.5 after residence time of 1h. The process also removes other heavy elements, if present, without leaving any additional toxic residue. The small quantity of solid sludge containing mainly ferrihydrite with adsorbed arsenate passes the toxicity characteristic leaching procedure (TCLP) test. The estimated recurring cost is approximately USD 0.16per/m(3) of purified water. A high efficiency, an extremely low cost, safety, non-requirement of power and simplicity of operation make the technique potential for rural application.",
Arsenic,477031,"Therapeutic effects of Moringa oleifera on arsenic-induced toxicity in rats Abstract: Moringa oleifera Lamarack (English: Horseradish-tree, Drumstick-tree; Hindi: Saijan; Sanskrit: Shigru) belongs to the Moringaceae family, is generally known in the developing world as a vegetable, a medicinal plant and a source of vegetable oil. Besides, the plant is reported to have various biological activities, including hypocholesterolemic agent, regulation of thyroid hormone status, anti-diabetic agent, gastric ulcers, anti-tumor agent and hypotensive agent, used for treating various diseases such as inflammation, cardiovascular and liver diseases. Therapeutic efficacy of oral administration of seed powder of M. oleifera (500 mg/kg, orally, once daily) post arsenic exposure (100 ppm in drinking water for 4 months) was investigated in rats. Animals exposed to arsenic(III) showed a significant inhibition of delta-arninolevulinic acid dehydratase (ALAD) activity, decrease in reduced glutathione (GSH) level and an increase in reactive oxygen species (ROS) in blood. On the other hand, a significant decrease in hepatic ALAD, and an increase in delta-aminolevulinic acid synthetase (ALAS) activity was noted after arsenic exposure. These changes were accompanied by an increase in thiobarbiturc acid reactive substances (TBARS) level in liver and kidney. Activities of liver, kidney and brain superoxide dismutase (SOD) and catalase also showed a decrease on arsenic exposure. Administration of M. oleifera seed powder post arsenic exposure, exhibited significant recovery in blood ALAD activity while, it restored blood GSH and ROS levels. Most of the other blood biochemical variables remained unchanged on M. oleifera supplementation. A significant protection in the altered ALAD and ALAS activities of liver and TBARS level in liver and kidney was however, observed after M. oleifera administration. Interestingly, there was a marginal but significant depletion of arsenic from blood, liver and kidneys. The results, thus lead us to conclude that post arsenic exposure administration with the seed powder of M. oleifera has significant role in protecting animals from arsenic-induced oxidative stress and in the depletion of arsenic concentration. Further studies thus can be recommended for determining the effect of co-administrating seed powder of M. oleifera during chelation therapy with a thiol chelator. (c) 2005 Elsevier B.V. All rights reserved.",
Arsenic,1358650,"Quantitative PCR analysis of c-erb B-2 (HER2/neu) gene amplification and comparison with p185(HER2/neu) protein expression in breast cancer drill biopsies Abstract: A PCR assay using capillary electrophoresis was designed for the detection of c-erbB-2 gene amplification in alcohol-formalin-acetic acid (AFA)-fixed, paraffin-embedded biopsies from 81 consecutive breast tumors. c-erbB-2 expression was analyzed in the same samples using immuno-histochemistry (IHC). In the competitive PCR assay, a single pTag plasmid containing a 4-nucleotide (nt)-deleted copy of a 124-nt sequence of c-erbB-2 and a 4-nt-deleted copy of a 120-nt sequence of GAPDH was co-amplified with genomic DNA extracted from 3 10-micrometer-thick tissue sections of the tumor biopsy. The percentage of tumor cells in the biopsy specimen and the percentage of tumor cells stained with the membrane anti-c-erbB-2 monoclonal antibody CB11 were recorded by a single pathologist on 2 consecutive sections. Among 81 consecutive tumor biopsies assayed by PCR, 21 (26%) displayed unequivocal c-erbB-2 amplification (actual gene copy number, AGCN &gt; 4), 47 (58%) displayed no c-erbB-2 amplification (AGCN &lt;/= 2) and 7 (9%) could not be analyzed due to an insufficient amount of DNA. Six samples (7%) were considered inconclusive since the percentage of tumor cells was &lt;20%. Analysis of c-erbB-2 expression by IHC showed that among the 21 amplified specimens 15 displayed strong staining, while all non-amplified samples (47) displayed no or only weak staining. The concordance of the 2 techniques was 91%. We conclude that c-erbB-2 gene amplification can be accurately quantitated by competitive PCR performed on small, fixed and embedded tumor samples.",
Arsenic,1033264,"Evaluation of a method for determination of total antimony, arsenic and tin in foodstuffs using measurement by atomic-absorption spectrophotometry with atomisation in a silica tube using the hydride generation technique Abstract: ",
Arsenic,1326925,"Contrasting roles of NF-kappaB and JNK in arsenite-induced p53-independent expression of GADD45alpha Abstract: Growth arrest and DNA damage-inducible protein 45alpha (GADD45alpha) is an important cell cycle checkpoint protein that arrests cells at G2/M phase by inhibiting the activity of G2-specific kinase, cyclin B/p34cdc2. We report here that arsenite induces GADD45alpha expression in a p53-independent fashion and that this GADD45alpha induction by arsenite is regulated by NF-kappaB and c-Jun-N-terminal kinase (JNK) oppositely. In human bronchial epithelial cells overexpressing a kinase-mutated form of IkappaB kinase beta (IKKbeta-KM), the activation of NF-kappaB was inhibited. However, the G2/M cell cycle arrest and expression of GADD45alpha was substantially enhanced in response to arsenite in these cells. Expression of a dominant-negative mutant of SEK1 that blocks JNK activation decreased arsenite-induced GADD45alpha expression. Analysis of GADD45alpha expression in both wild-type and p53-/- fibroblasts indicated that the induction of GADD45alpha by arsenite was independent of the status of p53 protein.",
Arsenic,1579404,"The system modulating ROS content in germinating seeds of two Brazilian savanna tree species exposed to As and Zn Abstract: The effects of increasing arsenic (0, 10, 50, 100 mg L?1) and zinc (0, 50, 80, 120, 200 mg L?1) doses on germination and oxidative stress markers (H2O2, MDA, SOD, CAT, APX, and GR) were examined in two Brazilian savanna tree species (Anadenanthera peregrina and Myracrodruon urundeuva) commonly used to remediate contaminated soils. The deleterious effects of As and Zn on seed germination were due to As- and Zn-induced H2O2 accumulation and inhibition of APX and GR activities, which lead to oxidative damage by lipid peroxidation. SOD and CAT did not show any As- and Zn-induced inhibition of their activities as was seen with APX and GR. We investigated the close relationships between seed germination success under As and Zn stress in terms of GR and, especially, APX activities. Increased germination of A. peregrina seeds exposed to 50 mg L?1 of Zn was related to increased APX activity, and germination in the presence of As (10 mg L?1) was observed only in M. urundeuva seeds that demonstrated increased APX activity. All the treatments for both species in which germination decreased or was inhibited showed decreases in APX activity. A. peregrina seeds showed higher Zn-tolerance than M. urundeuva, while the reverse was observed with arsenic up to exposures of 10 mg L?1.",
Arsenic,2064191,"Selected arsenic species: As(III), As(V) and dimethylarsenic acid (DMAA) in Xerocomus badius fruiting bodies Abstract: The aim of the study was to determine the content of As(III), As(V) and DMAA (dimethylarsinic acid) in Xerocomus badius fruiting bodies collected from selected Polish forests from areas subjected to very low or high anthropopressure and some commercially available samples obtained from the Polish Sanitary Inspectorate. The arsenic species determination was provided by two independent HPLC-HG-AAS hyphenated systems. The results show high levels (up to 27.1, 40.5 and 88.3mgkg(-1) for As(III), As(V) and DMAA, respectively) of arsenic and occurrence of different species in mushrooms collected from areas subjected to high anthropopressure and two commercially available samples. For mushroom samples collected from areas not subjected to high anthropopressure and two commercially available samples the arsenic species level was below 0.5mgkg(-1) for each arsenic form. Therefore, the accumulation of arsenic by mushrooms may lead to high (toxic for humans) arsenic concentrations, and arsenic species levels should be monitored in mushroom foodstuffs.",
Arsenic,1292197,"Arsenic Contamination in Soil-Water-Plant (Rice, Oryza sativa L.) Continuum in Central and Sub-mountainous Punjab, India Abstract: In the present study, Arsenic (As) concentrations in underground water, soil, and plants (rice) and their inter-relationships in central and sub-mountainous Punjab, India were studied. Approximately, 32 % of the tubewell water samples had As concentrations greater than the maximum permissible limit (10 ?g As L(-1)) set by the World Health Organization (WHO) whereas in hand pump waters, As concentrations were within the safe range (i.e. &lt;10 ?g As L(-1)). As concentrations in tubewell waters were significantly correlated with As concentrations in surface soil (r = 0.57; P &lt; 0.05) and plant samples (r = 0.27-0.82; P &lt; 0.05) in central and sub-mountainous Punjab. The estimated daily intake of As through human consumption in rural and urban population was 0.016 and 0.012 ?g day(-1) kg(-1) body weight respectively.",
Arsenic,627382,"Associations between drinking water and urinary arsenic levels and skin lesions in Bangladesh Abstract: The present study examined the associations between drinking water and urinary arsenic levels and skin lesions among 167 residents of three contiguous villages in Bangladesh. Thirty-six (21.6%) had skin lesions (melanosis, hyperkeratosis, or both), of which 13 (36.1%) occurred in subjects who were currently drinking water containing concentrations of arsenic < 50 micrograms/L. The risk for skin lesions in relation to the exposure estimates based on urinary arsenic was elevated more than 3-fold, with the odds ratios for the highest versus the lowest quartiles being 3.6 (95% confidence interval, 1.2 to 12.1) for urinary total arsenic and 3.2 (95% confidence interval, 1.1 to 10.0) for urinary creatinine-adjusted total arsenic. The risks for skin lesions in relation to the exposure estimates based on arsenic in drinking water were less strongly elevated, with the odds ratios for the highest versus the lowest quartiles of exposure being 1.7 (95% confidence interval, 0.6 to 5.1) for drinking-water arsenic and 2.3 for cumulative arsenic index. The study suggests that arsenic exposure is associated with skin lesions in the Bangladesh population and that urinary arsenic may be a stronger predictor of skin lesions than arsenic in drinking water in this population.",
Arsenic,627250,"CYP1A1 and GSTM1 genetic polymorphisms in lung cancer populations exposed to arsenic in drinking water Abstract: Region II of Chile is the most important copper mining area in the world and it shows the highest lung cancer mortality rate in the country (35/100,000). The population in Antofagasta, the main city of Region II, was exposed from 1958 to 1970 to 860 microg m(-3) arsenic (As) in drinking water and has currently been declining to 40 microg m(-3). Glutathione serves as a reducing agent and glutathione S-transferase (GST) may have an important role in As methylation capacity and body retention. In the current study, the null genotype of GSTM1 and the MspI polymorphism of CYP450 1A1 were investigated in lung cancer patients and in healthy volunteers of Region II. In males, the 2A genotype of MspI represented a highly significant estimated relative lung cancer risk (OR=2.60). Relative lung cancer risk for the combined 2A/null GSTM1 genotypes was 2.51, which increased with the smoking habit (OR=2.98). In Region II, the cancer mortality rate for As-associated cancers at least partly might be related to differences in As biotransformation. Genetic biomarkers such as 2A and GSTM1 polymorphisms in addition to DR70 as screening biomarkers might provide relevant information to identify individuals with a high risk for lung cancer as prevention and protection actions to protect public health.",
Arsenic,81027,"Arsenic-induced neural tube defects in mice: Alterations in cell cycle gene expression Abstract: The potential of arsenic to cause neural tube defects (NTD) in the human population remains a topic of controversy. While clearly toxic, the lack of well-defined human epidemiologic studies on this subject has made it difficult to fully understand the effects arsenic may have on the developing human neural tube. In the absence of good clinical data, we have tried to develop a murine model where hypotheses about the reproductive toxicity of arsenate can be tested. For these studies a murine strain (LM/Bc) that has proven to be susceptible to arsenic-induced NTD was use. Because cellular proliferation is vital for normal neural tube closure (NTC) to occur, in the present study we investigated whether an acute arsenate treatment could alter the expression of several cell cycle genes during murine neurulation. Pregnant LM/Bc dams were injected intraperitoneally on gestation day (GD) 7:12 (day:hour) and 8:12 with 40 mg/kg of arsenate, a treatment that causes exencephaly in 90 to 100% of the exposed fetuses. Neural tubes were then isolated from both control and arsenic treated embryos at GD 9:00, 9:12, 10:00, and 10:12, which encompasses all the stages of neurulation for this murine strain. Using the molecular techniques of in situ transcription and antisense RNA amplification (RT/aRNA) the expression pattern for bcl-2, p53, wee-1, and wnt-1 was analyzed at each of these time points. In the neural tubes isolated from control embryos, the expression of all four genes was significantly altered as neurulation progressed, demonstrating their developmental regulation. Following arsenate treatment, however, there was a significant upregulation in the expression of bcl-2 and p53 at gestational day 9:0, compared to their control values. The heightened expression of both of these genes suggests that arsenic inhibits cell proliferation, rather than inducing apoptosis, which delayed NTC and ultimately led to the neural tube defects observed in exposed embryos.",
Arsenic,8638,"Effects of glutathione depletion on the acute nephrotoxic potential of arsenite and on arsenic metabolism in hamsters Abstract: Our previous study showed that pretreatment with buthionine sulfoximine (BSO), which inhibits glutathione synthesis, results in acute renal failure with oliguria in hamsters ingesting sodium arsenite (5 mg As/kg). For a deeper understanding of the relationship between arsenic metabolism and the subsequent development of nephrotoxicity, we studied excretion, tissue retention, biotransformation, pharmacokinetics, and histopathological events in the kidneys of hamsters both with and without BSO pretreatment. The total amount of arsenic excreted in the urine and feces within 72 hr of arsenite administration was more than fivefold lower in BSO-pretreated animals than in the controls without pretreatment (9.2 versus 53.4% of the arsenic dose). The persistence of high amounts of total arsenic was apparent in the blood, liver, and kidneys of BSO-pretreated hamsters, even though the content of inorganic arsenic steadily decreased with time. The disappearance of inorganic arsenic from the blood showed a biphasic elimination pattern characterized first by a rapid component with a half-life of 4.5 hr and second by a slower component with a half-life of 58.0 hr in the BSO-pretreated hamsters, while these half-lives were 0.6 and 11.0 hr, respectively, in the controls. BSO pretreatment not only impaired the excretion of inorganic arsenic, but also impaired its methylation. Combined BSO/arsenite treatment resulted in renal tubular necrosis which was prominent at 1 hr after arsenite administration. By 1 hr, the renal content of inorganic arsenic in the BSO-pretreated animals was 1.7 times higher than that in the controls. This study demonstrates that glutathione depletion elicits the nephrotoxic manifestations of arsenic poisoning.",
Arsenic,628058,"Arsenic and cardiovascular disease Abstract: Chronic arsenic exposure is a worldwide health problem. Although arsenic-induced cancer has been widely studied, comparatively little attention has been paid to arsenic-induced vascular disease. Epidemiological studies have shown that chronic arsenic exposure is associated with increased morbidity and mortality from cardiovascular disease. In addition, studies suggest that susceptibility to arsenic-induced vascular disease may be modified by nutritional factors in addition to genetic factors. Recently, animal models for arsenic-induced atherosclerosis and liver sinusoidal endothelial cell dysfunction have been developed. Initial studies in these models show that arsenic exposure accelerates and exacerbates atherosclerosis in apolipoprotein E-knockout mice. Microarray studies of liver mRNA and micro-RNA abundance in mice exposed in utero suggest that a permanent state of stress is induced by the arsenic exposure. Furthermore, the livers of the arsenic-exposed mice have activated pathways involved in immune responses suggesting a pro-hyperinflammatory state. Arsenic exposure of mice after weaning shows a clear dose-response in the extent of disease exacerbation. In addition, increased inflammation in arterial wall is evident. In response to arsenic-stimulated oxidative signaling, liver sinusoidal endothelium differentiates into a continuous endothelium that limits nutrient exchange and waste elimination. Data suggest that nicotinamide adenine dinucleotide phosphate oxidase-derived superoxide or its derivatives are essential second messengers in the signaling pathway for arsenic-stimulated vessel remodeling. The recent findings provide future directions for research into the cardiovascular effects of arsenic exposure.",
Arsenic,1579349,"Establishment of toxic metal reference range in tobacco from US cigarettes Abstract: Smoking remains the leading cause of preventable death in the United States. There are numerous harmful substances in tobacco and tobacco smoke. Among the more than 4,000 identified compounds in smoke, many metals contribute to the health risks associated with tobacco use. Specific metals found in tobacco and tobacco smoke have been classified as carcinogens by the International Agency for Research on Cancer. Exposure to toxic metals can cause outcomes including inflammation, sensitization and carcinogenesis. Metals in tobacco are transported in tobacco smoke proportionally with their concentrations in tobacco filler for a given cigarette design. To quantitatively examine the metal content in numerous tobacco products, high throughput methods are desired. This study developed a simple, rapid tobacco digestion method coupled with a sensitive analytical method using inductively coupled plasma-mass spectrometry. Because of known memory effects and volatility of mercury, quantitative determinations of mercury were made with a direct combustion analyzer. The methods were utilized to examine arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury and nickel contents in cigarette tobacco and to establish a reference range for the metals in 50 varieties of cigarettes available in the US. These results are comparable to the limited data sets reported by others and with available standard reference material values.",
Arsenic,2088543,"Treatment of wastewater containing arsenic using Rhazya stricta as a new adsorbent Abstract: The effective removal of heavy metals from aqueous wastes is among the most important issues for many industrialized countries. Removal of arsenic (As) from aqueous solutions was studied using Rhazia stricta biomass. The batch experiments are carried out to investigate the effect of the significant process parameters such as pH, contact time, solute concentration and adsorbent dose. The optimum pH required for maximum adsorption was found to be 5. The equilibrium data for the adsorption of As(V) on R. stricta are tested with various adsorption isotherm models such as Langmuir, Freundlich, Tempkin and Generalized equation. Results indicate the following order to fit the isotherm: Langmuir (1 and 2)?>?Tempkin?>?Generalized form?>?Freundlich. A comparison of two kinetic models showed that our data fitted well to the Elovich model.",
Arsenic,628370,"The urinary excretion of arsenic metabolites after a single oral administration of dimethylarsinic acid to rats Abstract: The biotransformation following oral administration of dimethylarsinic acid (DMA), an organoarsenical herbicide and the main metabolite of inorganic arsenic in mammals, was studied in rats. Male F344/DuCrj rats were administered a single dose of DMA (50 mg/kg) orally. Urine was collected at 0, 2, 4, 8, 10, 24, and 48 h after administration by forced urination. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS). The proportions of urinary elimination of DMA, trimethylarsine oxide (TMAO), methylarsonic acid (MMA), an unidentified arsenic metabolite, and arsenite were determined at various timepoints after administration. Unmetabolized DMA was the most common form excreted during the first 4 h. Thereafter, a gradual decrease in the proportion of DMA was observed, while progressive increases in those of TMAO, the unidentified metabolite, and arsenite occurred. The proportion of TMAO excreted amounted to over 50% of all arsenic in urine between 6 and 24 h. The proportion of the unidentified metabolite and arsenite were each approximately 10% at 10 and 24 h after administration. The findings indicate that DMA administered to rats was initially excreted as unchanged DMA, and later as the methylated metabolite, TMAO. Arsenite, a demethylated metabolite of DMA, also was excreted later than elimination of DMA and TMAO. The hypothesis of demethylation by intestinal microorganisms can be supported by comparing the metabolites following oral and intraperitoneal administration. The unidentified metabolite was readily decomposed by HCl but was left unchanged by NaOH; these findings suggest that it was present in a complexed form in urine.",
Arsenic,2149276,"Comparison of metal(loid) concentrations in water, sediments and fish from two large shallow lakes Abstract: ",
Arsenic,2343515,"Elements of concern in fillets of bighead and silver carp from the Illinois River, Illinois Abstract: Efforts to control invasive bighead (Hypophthalmichthys nobilis) and silver carp (H. molitrix) may include harvest for human consumption. We measured concentrations of arsenic (As), mercury (Hg), and selenium (Se) in fillets from silver and bighead carp collected from the lower Illinois River, Illinois, USA, to determine whether concentrations were of health concern and differed by species, size, and location. Concentrations of total As were below detection limits in most bighead (92%) and silver (77%) carp fillets, whereas inorganic As was below detection limits in all samples. Mean Hg concentrations were greater in bighead (0.068 mg kg(-1)) than in silver carp (0.035 mg kg(-1)), and were smallest in carp from the confluence of the Illinois and Mississippi rivers. Mercury concentrations in fillets were positively correlated with body mass in both species. Concentrations of Hg were below the US Food and Drug Administration's (USFDA) action level (1 ppm as methyl-Hg); however, concentrations in some bighead (70%) and silver (12%) carp fell within the range that would invoke a recommendation to limit meals in sensitive cohorts. Mean Se concentrations were greater in silver (0.332 mg kg(-1)) than in bighead (0.281 mg kg(-1)) carp fillets, and were below the 1.5 mg kg(-1) limit for an unrestricted number of meals/month. The mean molar ratio of Se:Hg in fillets was lower in bighead (14.0) than in silver (29.1) carp and was negatively correlated with mass in both species Concentrations of Hg in bighead and silver carp fillets should be considered when assessing the risks associated with the use of these species as a protein source.",
Arsenic,528960,"Exposure assessment of persistent organic pollutants and metals in Mexican children Abstract: Environmental policies in Mexico have contributed to the reduction in the production or use of some persistent organic pollutants (POPs) and metals. How ever, monitoring of POPs concentrations in humans living in hot spots is lacking. Therefore, the objective of this study was to con duct a screening for POPs and metals first in Mexican children living in high-risk areas. During the year 2004, we analyzed a total of 229 healthy children (aged 6-12 years old) who resided in communi ties located in nine Mexican states. Organochlorine insecticides, PCBs and metals were quantified in plasma and urine samples. We detected p'p-DDE in all the children; more over, p'p-DDT, lindane and hexa chloro benzene were detected respectively in 14%, 85% and 10% of the children studied. Mea sur able levels of PCBs were recorded in only one community, where six of 14 PCB congeners assayed were detected (numbers 52, 118, 138, 153, 170 and 180). All the children had detect able levels of lead in their blood (mean level, 4.6 mu g dL(-1)); further more, 57% of the children studied had levels higher than 5.0 mu g/dL. The mean level of urinary arsenic (UAs) for all the children was 22.35 mu g g(-1) creatinine and 15% of those children had concentrations of UAs above 50 mu g g(-1) creatinine. For cadmium, the mean urinary level was 0.78 mu g g(-1) creatinine, and only one percent of the children had values above 2.0 mu g g(-1) creatinine. The results can not be generalized since the communi ties selected are not representative of the Mexican population; how ever, they indicate that Mexican children are exposed to chemicals and some at risk levels. (C) 2008 Elsevier Ltd. All rights reserved.",
Arsenic,2278337,"Risk factors and predictors of levodopa-induced dyskinesia among multiethnic Malaysians with Parkinson's disease Abstract: Chronic pulsatile levodopa therapy for Parkinson's disease (PD) leads to the development of motor fluctuations and dyskinesia. We studied the prevalence and predictors of levodopa-induced dyskinesia among multiethnic Malaysian patients with PD. Methods: This is a cross-sectional study involving 95 patients with PD on uninterrupted levodopa therapy for at least 6 months. The instrument used was the UPDRS questionnaires. The predictors of dyskinesia were determined using multivariate logistic regression analysis. Results: The mean age was 65.6 ± 8.5 years. The mean onset age was 58.5 ± 9.8 years. The median disease duration was 6 (7) years. Dyskinesia was present in 44% (n = 42) with median levodopa therapy of 3 years. There were 64.3% Chinese, 31% Malays, and 3.7% Indians and other ethnic groups. Eighty-one percent of patients with dyskinesia had clinical fluctuations. Patients with dyskinesia had lower onset age (?p &lt; 0.001), longer duration of levodopa therapy (?p &lt; 0.001), longer disease duration (?p &lt; 0.001), higher total daily levodopa dose (?p &lt; 0.001), and higher total UPDRS scores (?p = 0.005) than patients without dyskinesia. The three significant predictors of dyskinesia were duration of levodopa therapy, onset age, and total daily levodopa dose. Conclusions: The prevalence of levodopa-induced dyskinesia in our patients was 44%. The most significant predictors were duration of levodopa therapy, total daily levodopa dose, and onset age.",
Arsenic,1256736,"Contamination and adulteration of herbal medicinal products (HMPs): an overview of systematic reviews Abstract: PURPOSE: The aim of this overview of systematic reviews is to summarise and critically evaluate the evidence from systematic reviews of the adulteration and contamination of herbal medicinal products (HMPs). METHODS: Five electronic databases were searched to identify all relevant systematic reviews. RESULTS: Twenty-six systematic reviews met our inclusion criteria. The most commonly HMPs were adulterated or contaminated with dust, pollens, insects, rodents, parasites, microbes, fungi, mould, toxins, pesticides, toxic heavy metals and/or prescription drugs. The most severe adverse effects caused by these adulterations were agranulocytosis, meningitis, multi-organ failure, perinatal stroke, arsenic, lead or mercury poisoning, malignancies or carcinomas, hepatic encephalopathy, hepatorenal syndrome, nephrotoxicity, rhabdomyolysis, metabolic acidosis, renal or liver failure, cerebral edema, coma, intracerebral haemorrhage, and death. Adulteration and contamination of HMPs were most commonly noted for traditional Indian and Chinese remedies, respectively. CONCLUSIONS: Collectively these data suggest that there are reasons for concerns with regards to the quality of HMPs. Adulteration and contamination of HMPs can cause serious adverse effects. More stringent quality control and its enforcement seem to be necessary to avoid health risks.",
Arsenic,69621,"Potential impact of acid precipitation on arsenic and selenium Abstract: The potential impact of acidic precipitation on the environmental mobility of the metalloids arsenic (As) and selenium (Se) has not been given much attention and is poorly understood. As with other elements, the interest here is the potential effect of environmental acidification on environmental behavior in ways that are relevant to human exposure to these metalloids. Available information on acid precipitation and the environmental behavior of these metalloids do, however, permit some preliminary conclusions to be drawn. Both As and Se appear to be mobilized from household plumbing into tap water by the corrosive action of soft, mildly acidic water, while surface water catchment systems in areas impacted by acidic deposition may contain elevated soluble As levels. Acidification of aquatic ecosystems that are drinking water sources may pose the prospect of enhanced release of As from sediment to water as well as reduction in water levels of Se. Acidification of ground waters, where As appears to be especially mobile, is of particular concern in this regard. The potential impact of acidic deposition on As and Se in soils cannot readily be assessed with respect to human exposure, but it would appear that the behavior of these metalloids in poorly buffered, poorly immobilizing soils, e.g., sandy soils of low metal hydrous oxide content, would be most affected. The effect is opposite for the two elements; lowered pH would appear to enhance As mobility and to reduce Se availability. Altered acidity of both soil and aquatic systems poses a risk for altered biotransformation processes involving both As and Se, thereby affecting the relative amounts of different chemical forms varying in their toxicity to humans as well as influencing biogeochemical cycling.",
Arsenic,1797797,"Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities Abstract: The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.0, while representative coal fly ash samples from two different locations in the coal fly ash impoundment were used to produce two alkaline ash leachates with pH 7.4 and 8.2. The arsenic found in the ash leachates was present as arsenate [As(V)]. Adsorption isotherm experiments were carried out to determine the adsorption parameters required for predicting the uptake of arsenic from the ash leachates. For all soils and leachates, the adsorption of arsenic followed the Langmuir and Freundlich equations, indicative of the favorable adsorption of arsenic from leachates onto all soils. The uptake of arsenic was evaluated as a function of ash leachate characteristics and the soil components. The uptake of arsenic from alkaline ash leachates, which occurred mainly as calcium hydrogen arsenate, increased with increasing clay fraction of soil and with increasing soil organic matter of the alkaline soils. Appreciable uptake of arsenic from alkaline ash leachates with different pH and arsenic concentration was observed for the alkaline soils, thus attenuating the contamination of groundwater downstream of the retired coal fly ash impoundment.",
Arsenic,1015682,"Solution Structure of Mycobacterium tuberculosis NmtR in the Apo State: Insights into Ni(II)-Mediated Allostery Abstract: Mycobacterium tuberculosis is an obligate human respiratory pathogen that encodes approximately 10 arsenic repressor (ArsR) family regulatory proteins that allow the organism to respond to a wide range of changes in its immediate microenvironment. How individual ArsR repressors have evolved to respond to selective stimuli is of intrinsic interest. The Ni(II)/Co(II)-specific repressor NmtR and related actinomycete nickel sensors harbor a conserved N-terminal ?-NH(2)-Gly2-His3-Gly4 sequence. Here, we present the solution structure of homodimeric apo-NmtR and show that the core of the molecule adopts a typical winged-helix ArsR repressor (?1-?2-?3-?R-?1-?2-?5) &quot;open conformation&quot; that is similar to that of the related zinc sensor Staphylococcus aureus CzrA, but harboring long, flexible N-terminal (residues 2-16) and C-terminal (residues 109-120) extensions. Binding of Ni(II) to the regulatory sites induces strong paramagnetic broadening of the ?5 helical region and the extreme N-terminal tail to residue 10. Ratiometric pulse chase amidination mass spectrometry reveals that the rate of amidination of the ?-amino group of Gly2 is strongly attenuated in the Ni(II) complex relative to the apo state and noncognate Zn(II) complex. Ni(II) binding also induces dynamic disorder on the microsecond to millisecond time scale of key DNA interacting regions that likely contributes to the negative regulation of DNA binding by Ni(II). Molecular dynamics simulations and quantum chemical calculations reveal that NmtR readily accommodates a distal Ni(II) hexacoordination model involving the ?-amine and His3 of the N-terminal region and ?5 residues Asp91', His93', His104, and His107, which collectively define a new metal sensing site configuration in ArsR family regulators.",
Arsenic,627998,"Lifetime exposure to arsenic in drinking water and bladder cancer: A population-based case-control study in Michigan, USA Abstract: OBJECTIVE: Arsenic in drinking water has been linked with the risk of urinary bladder cancer, but the dose-response relationships for arsenic exposures below 100 microg/L remain equivocal. We conducted a population-based case-control study in southeastern Michigan, USA, where approximately 230,000 people were exposed to arsenic concentrations between 10 and 100 microg/L. METHODS: This study included 411 bladder cancer cases diagnosed between 2000 and 2004, and 566 controls recruited during the same period. Individual lifetime exposure profiles were reconstructed, and residential water source histories, water consumption practices, and water arsenic measurements or modeled estimates were determined at all residences. Arsenic exposure was estimated for 99% of participants' person-years. RESULTS: Overall, an increase in bladder cancer risk was not found for time-weighted average lifetime arsenic exposure >10 microg/L when compared with a reference group exposed to <1 microg/L (odds ratio (OR) = 1.10; 95% confidence interval (CI): 0.65, 1.86). Among ever-smokers, risks from arsenic exposure >10 microg/L were similarly not elevated when compared to the reference group (OR = 0.94; 95% CI: 0.50, 1.78). CONCLUSIONS: We did not find persuasive evidence of an association between low-level arsenic exposure and bladder cancer. Selecting the appropriate exposure metric needs to be thoughtfully considered when investigating risk from low-level arsenic exposure.",
Arsenic,618204,"Interactions of arsenic with zinc, copper and iron in human hepatic cells Abstract: The purpose of this study is to examine interactions of arsenic (As) with copper (Cu), zinc (Zn) and iron (Fe) in human hepatic cells. The 100 ÃŽÂ¼M As and Cu alone reduced viability of the cells by 25 and 90%, respectively. For the other metals (Zn and Fe), no significant difference was found as compared to the control. The concentrations of 100 ÃŽÂ¼M Cu alone decreased in cell viability significantly as compared with control. For the 10 ÃŽÂ¼M As + 5 ÃŽÂ¼M to 100 ÃŽÂ¼M Zn, no significant changes were observed as compared to As alone. Although 5 - 100 ÃŽÂ¼M Fe alone had no effect on the proliferation of human hepatic cells, there were significant increases in cell viability after exposure to 10 ÃŽÂ¼M As + 100 ÃŽÂ¼M Fe as compared to As alone. Significant increases in cell viability were not observed below the concentrations of 10 ÃŽÂ¼M As + 100 ÃŽÂ¼M Fe. For the concentrations of 10 ÃŽÂ¼M As + 100 ÃŽÂ¼M Cu, a significant decrease was found as compared to As alone. These results indicated that the high concentration of Fe protected against As toxicity in human hepatic cells and that the high concentration of Cu accelerated As toxicity against human hepatic cells. [ABSTRACT FROM AUTHOR] Copyright of Trace Elements & Electrolytes is the property of Dustri-Verlag Dr. Karl Feistle GmbH & Co., KG and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,627979,"Cyclin D1 induction through IkappaB kinase beta/nuclear factor-kappaB pathway is responsible for arsenite-induced increased cell cycle G1-S phase transition in human keratinocytes Abstract: Environmental and occupational exposure to arsenite is associated with an increased risk of human cancers, including skin, urinary bladder, and respiratory tract cancers. Although much evidence suggests that alterations in cell cycle machinery are implicated in the carcinogenic effect of arsenite, the molecular mechanisms underlying the cell cycle alterations are largely unknown. In the present study, we observed that exposure of human keratinocyte HaCat cells to arsenite resulted in the promotion of cell cycle progression, especially G(1)-S transition. Further studies found that arsenite exposure was able to induce cyclin D1 expression. The induction of cyclin D1 by arsenite required nuclear factor-kappaB (NF-kappaB) activation, because the inhibition of IkappaB phosphorylation by overexpression of the dominant-negative mutant, IKKbeta-KM, impaired arsenite-induced cyclin D1 expression and G1-S transition. The requirement of IkappaB kinase beta (IKKbeta) for cyclin D1 induction was further confirmed by the findings that arsenite-induced cyclin D1 expression was totally blocked in IKKbeta knockout (IKKbeta(-/-)) mouse embryo fibroblasts. In addition, knockdown of cyclin D1 expression using cyclin D1-specific small interference RNA significantly blocked arsenite-induced cell cycle progression in HaCat cells. Taken together, our results show that arsenite-induced cell cycle from G(1) to S phase transition is through IKKbeta/NF-kappaB/cyclin D1-dependent pathway.",
Arsenic,1019737,"Effect of arsenosugar ingestion on urinary arsenic speciation Abstract: We developed and evaluated a method for the determination of microgram/L concentrations of individual arsenic species in urine samples. We have mainly studied arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA) because these are the most commonly used biomarkers of exposure by the general population to inorganic arsenic and because of concerns over these arsenic species on their toxicity and carcinogenicity. We have also detected five unidentified urinary arsenic species resulting from the metabolism of arsenosugars. We combined ion pair liquid chromatography with on-line hydride generation and subsequent atomic fluorescence detection (HPLC/HGAFS). Detection limits, determined as three times the standard deviation of the baseline noise, are 0.8, 1.2, 0.7, and 1.0 mu/L arsenic for arsenite, arsenate, MMAA, and DMAA, respectively. These correspond to 16, 24, 14, and 20 pg of arsenic, respectively, for a 20-muL sample injected for analysis. The excellent detection limit enabled us to determine trace concentrations of arsenic species in urine samples from healthy subjects who did not have excess exposure to arsenic. There was no need for any sample pretreatment step. We used Standard Reference Materials, containing both normal and increased concentrations of arsenic, to validate the method. Interlaboratory studies with independent techniques also confirmed the results obtained with the HPLC/HGAFS method. We demonstrated an application of the method to the determination of arsenic species in urine samples after the ingestion of seaweed by four volunteers. We observed substantial increases of DMAA concentrations in the samples collected from the volunteers after the consumption of seaweed. The increase of urinary DMAA concentration is due to the metabolism of arsenosugars that are present in the seaweed. Our results suggest that the commonly used biomarkers of exposure to inorganic arsenic, based on the measurement of arsenite, arsenate, MMAA, and DMAA, are not reliable when arsenosugars are ingested from the diet.",
Arsenic,1015960,"Arsenic exposure from drinking water and mortality from cardiovascular disease in Bangladesh: Prospective cohort study Abstract: <strong>OBJECTIVE: </strong>To evaluate the association between arsenic exposure and mortality from cardiovascular disease and to assess whether cigarette smoking influences the association.<br /><br /><strong>DESIGN: </strong>Prospective cohort study with arsenic exposure measured in drinking water from wells and urine.<br /><br /><strong>SETTING: </strong>General population in Araihazar, Bangladesh.<br /><br /><strong>PARTICIPANTS: </strong>11,746 men and women who provided urine samples in 2000 and were followed up for an average of 6.6 years.<br /><br /><strong>MAIN OUTCOME MEASURE: </strong>Death from cardiovascular disease.<br /><br /><strong>RESULTS: </strong>198 people died from diseases of circulatory system, accounting for 43% of total mortality in the population. The mortality rate for cardiovascular disease was 214.3 per 100,000 person years in people drinking water containing &lt;12.0 µg/L arsenic, compared with 271.1 per 100,000 person years in people drinking water with ? 12.0 µg/L arsenic. There was a dose-response relation between exposure to arsenic in well water assessed at baseline and mortality from ischaemic heart disease and other heart disease; the hazard ratios in increasing quarters of arsenic concentration in well water (0.1-12.0, 12.1-62.0, 62.1-148.0, and 148.1-864.0 µg/L) were 1.00 (reference), 1.22 (0.65 to 2.32), 1.35 (0.71 to 2.57), and 1.92 (1.07 to 3.43) (P = 0.0019 for trend), respectively, after adjustment for potential confounders including age, sex, smoking status, educational attainment, body mass index (BMI), and changes in urinary arsenic concentration since baseline. Similar associations were observed when baseline total urinary arsenic was used as the exposure variable and for mortality from ischaemic heart disease specifically. The data indicate a significant synergistic interaction between arsenic exposure and cigarette smoking in mortality from ischaemic heart disease and other heart disease. In particular, the hazard ratio for the joint effect of a moderate level of arsenic exposure (middle third of well arsenic concentration 25.3-114.0 µg/L, mean 63.5 µg/L) and cigarette smoking on mortality from heart disease was greater than the sum of the hazard ratios associated with their individual effect (relative excess risk for interaction 1.56, 0.05 to 3.14; P = 0.010).<br /><br /><strong>CONCLUSIONS: </strong>Exposure to arsenic in drinking water is adversely associated with mortality from heart disease, especially among smokers.",
Arsenic,2343547,"Removal of arsenate from aqueous media by magnetic chitosan resin immobilized with molybdate oxoanions Abstract: Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin obtained was chemically modified through the reaction with tetraethylenepentamine ligand. The obtained resin was loaded with Mo(VI) and investigated. The adsorption characteristics of the obtained resin toward As(V) at different experimental conditions were investigated by means of batch and column methods. The resin showed high affinity and fast kinetics for the adsorption of As(V) where an uptake value of 1.30 mmol g(-1) was reported in 6 min at 25 A degrees C. Various parameters such as pH, agitation time, As(V) concentration and temperature had been studied. The kinetics and thermodynamic behavior of the adsorption reaction were defined. These data indicated an endothermic and spontaneous adsorption process and kinetically followed pseudo-second-order model, Fickian diffusion low and Elovich equation. Breakthrough curves for the removal of As(V) were studied at different flow rates and bed heights. The critical bed height for the studied resin column was found to be 0.656 cm at flow rate of 4 mL min(-1). The mechanism of interaction between As(V) and resin's active sites was discussed. Regeneration and durability of the loaded resin toward the successive cycles were also clarified.",
Arsenic,656921,"Separating potential source exposure from background exposure in subsistence populations in developing countries Abstract: Risk assessment methods of developed countries have prescribed exposure assumptions for calculating health risks that are generally inappropriate for developing countries because of population, cultural, and social differences. For example, populations in developing countries are often subsistence users of natural resources with a more outdoor-oriented lifestyle. Assessments should thus measure specific dietary intake rates and contact rates with environmental media. Chemical analyses of food, environmental media, and any biomarkers of exposure should include a carefully matched reference population to distinguish between exposures due to naturally occurring metals in more mineralized areas and potential anthropogenic sources. Without a reference group, one might predict excess risk associated with the external source, even though exposure is due to background levels. For example, subsistence populations often have a simple diet with high ingestion rates of a few food types (e.g. 200 g/day wet weight of fish; 500 g/day of rice). These foods can be naturally elevated in arsenic (fish and rice) and mercury (fish). Conservative risk assessments that extrapolate toxicity from high to low doses can predict elevated risks for these naturally occurring elements (e.g. greater than 1 in 10?000 cancer risk for arsenic). Whether the calculated risks are actually indicative of harm to subsistence populations should be considered in light of the beneficial properties of the diet and the lack of alternative food choices",
Arsenic,1936115,"Maternal and early life arsenite exposure impairs neurodevelopment and increases the expression of PSA-NCAM in hippocampus of rat offspring Abstract: Although epidemiological investigations indicate that chronic arsenic exposure can induce developmental neurotoxicity in children, the molecular mechanisms are still poorly understood. Neural cell adhesion molecules (NCAMs) play critical roles during the development of nervous system. Polysialylation of NCAM (PSA-NCAM) is a critical functional feature of NCAM-mediated cell interactions and functions. The present study aimed at investigating the effects of maternal and early life arsenite exposure on NCAM and PSA-NCAM in rat offspring. To this end, mother rats were divided into three groups and exposed to 0, 2.72 and 13.6mg/L sodium arsenite, respectively, during gestation and lactation. After weaning, rat offspring drank the same solution as their mothers. Neural reflex parameters, arsenic level of hippocampus, ultra-structural changes of hippocampus, the expression of NCAM, PSA-NCAM and two polysialyltransferases (STX and PST) in rat offspring were assessed. Arsenite exposure significantly prolonged the time of completing reflex response of surface righting, negative geotaxis and cliff avoidance of rat offspring in 13.6mg/L As-exposed group. Neurons and capillaries presented pathological changes and the expression of NCAM, PSA-NCAM, STX and PST were up-regulated in hippocampus of rat offspring exposed to arsenite. These results indicated that maternal arsenite exposure increases the expression of PSA-NCAM, NCAM and polysialyltransferases in hippocampus of rat offspring on postnatal day (PND) 21 and PND120, which might contribute to the impaired neurodevelopment following arsenite exposure.",
Arsenic,628351,"Posttreatment with sodium arsenite alters the mutational spectrum induced by ultraviolet light irradiation in Chinese hamster ovary cells Abstract: Arsenic, a potent carcinogen, fails to induce gene mutations in mammalian cells. However, posttreatment of ultraviolet light (UV) irradiated cells with sodium arsenite synergistically enhances the mutation frequency on the hypoxanthine (guanine) phosphoribosyltransferase locus. To investigate the molecular mechanism of the comutagenic effects of sodium arsenite, we characterized the alterations of nucleotide sequences in 30 UV-induced and 39 sodium arsenite enhanced hprt mutants from Chinese hamster ovary K1 cells by direct sequencing of mRNA-PCR amplified cDNA. The majority of sequence alterations derived from UV irradiation (80%) and from sodium arsenite posttreatment (70%) were single base substitutions. UV irradiation induced all types of base substitutions. Among them, 57% were transversions. The frequency of transversions increased to 70% in sodium arsenite enhanced mutants. While base substitutions observed in UV-induced mutants were evenly distributed along with the whole coding region, exons 3 and 8 were most frequently mutated in sodium arsenite enhanced mutants. Sodium arsenite posttreatment did not alter the strand bias for mutation induction, i.e., 73% and 78%, of the mutations were located on the non-transcribed strand in UV-induced and sodium arsenite enhanced mutants, respectively. In contrast to UV-induced mutations, bases at the 5' position of TT and the 3' position of CT sequences were the most frequent mutation sites observed in sodium arsenite enhanced mutants. We hypothesize that sodium arsenite may interfere with the process of mutation fixation of TT and CT dimers during DNA replication.",
Arsenic,711007,"Pentavalent methylated arsenicals are substrates of human AQP9 Abstract: Liver aquaglyceroporin AQP9 facilitates movement of trivalent inorganic arsenite (As(III)) and organic monomethylarsonous acid (MAs(III)). However, the transport pathway for the two major pentavalent arsenic cellular metabolites, MAs(V) and DMAs(V), remains unknown in mammals. These products of arsenic metabolism, in particular DMAs(V), are the major arsenicals excreted in the urine of mammals. In this study, we examined the uptake of the two pentavalent organic arsenicals by human AQP9 in Xenopus laevis oocytes. Xenopus laevis oocytes microinjected with AQP9 cRNA exhibited uptake of both MAs(V) and DMAs(V) in a pH-dependent manner. The rate of transport was much higher at acidic pH (pH5.5) than at neutral pH. Hg(II), an aquaporin inhibitor, inhibited transport of As(III), MAs(III), MAs(V) and DMAs(V) via AQP9. However, phloretin, which inhibits water and glycerol permeation via AQP9, can only inhibit transport of pentavalent MAs(V) and DMAs(V) but not trivalent As(III) and MAs(III), indicating the translocation mechanisms of these arsenic species are not exactly the same. Reagents such as FCCP, valinomycin and nigericin that dissipate transmembrane proton potential or change the transmemebrane pH gradient did not significantly inhibit all arsenic transport via AQP9, suggesting the transport of pentavalent arsenic is not proton coupled. The results suggest that in addition to the initial uptake of trivalent inorganic As(III) inside cells, AQP9 plays a dual role in the detoxification of arsenic metabolites by facilitating efflux from cells.",
Arsenic,1015725,"A real-time biomonitoring system to detect arsenic toxicity by valve movement in freshwater clam Corbicula fluminea Abstract: Arsenic (As) is the element of greatest ecotoxicological concern in aquatic environments. Effective monitoring and diagnosis of As pollution via a biological early warning system is a great challenge for As-affected regions. The purpose of this study was to synthesize water chemistry-based bioavailability and valve daily rhythm in Corbicula fluminea to design a biomonitoring system for detecting waterborne As. We integrated valve daily rhythm dynamic patterns and water chemistry-based Hill dose-response model to build into a programmatic mechanism of inductance-based valvometry technique for providing a rapid and cost-effective dynamic detection system. A LabVIEW graphic control program in a personal computer was employed to demonstrate completely the functional presentation of the present dynamic system. We verified the simulated dissolved As concentrations based on the valve daily rhythm behavior with published experimental data. Generally, the performance of this proposed biomonitoring system demonstrates fairly good applicability to detect waterborne As concentrations when the field As concentrations are less than 1 mg L-1. We also revealed that the detection times were dependent on As exposure concentrations. This biomonitoring system could particularly provide real-time transmitted information on the waterborne As activity under various aquatic environments. This parsimonious C. fluminea valve rhythm behavior-based real-time biomonitoring system presents a valuable effort to promote the automated biomonitoring and offers early warnings on potential ecotoxicological risks in regions with elevated As exposure concentrations.",
Arsenic,1797815,"Developing and testing theory-based and evidence-based interventions to promote switching to arsenic-safe wells in Bangladesh Abstract: Millions of people in Bangladesh drink arsenic-contaminated water despite increased awareness of consequences to health. Theory-based and evidence-based interventions are likely to have greater impact on people switching to existing arsenic-safe wells than providing information alone. To test this assumption, we first developed interventions based on an empirical test of the Risk, Attitudes, Norms, Abilities and Self-regulation (RANAS) model of behaviour change. In the second part of this study, a cluster-randomised controlled trial revealed that in accordance with our hypotheses, information alone showed smaller increases in switching to arsenic-safe wells than information with reminders or information with reminders and implementation intentions.",
Arsenic,2298723,"Distribution and ecological risk assessment of heavy metals in surface sediments along southeast coast of the Caspian Sea Abstract: The present study aimed to evaluate heavy metal concentrations of Arsenic (As), Copper (Cu), Nickel (Ni), Lead (Pb) and Zinc (Zn), their spatial distribution, enrichment factor index (EF), the pollution load index (PLI) and potential ecological risk (PER) in two different seasons of the year (winter and summer) in surface sediments along southeast coast of the Caspian Sea. The results indicated that there were significant differences between concentrations of As, Ni and Pb in two different seasons. Considering PER, sediments from southeast Caspian coast had low ecological risk. According to PLI, sediment from the southeast coast had no pollution. Risk assessment showed that As threshold concentrations to occasionally be exceeded in the study area.",
Arsenic,627583,"Stimulation of reactive oxygen, but not reactive nitrogen species, in vascular endothelial cells exposed to low levels of arsenite Abstract: Elevated levels of arsenite, the trivalent form of arsenic, in drinking water correlates with increased vascular disease and vessel remodeling. Previous studies from this laboratory demonstrated that environmentally relevant concentrations of arsenite caused oxidant-dependent increases in nuclear transcription factor levels in cultured porcine vascular endothelial cells. The current studies characterized the reactive species generated in these cells exposed to levels of arsenite that initiate cell signaling. These exposures did not deplete 5'-triphosphate, nor did they affect basal or bradykinin-stimulated intracellular free Ca2+ levels, indicating that they were not lethal. Electron paramagnetic resonance (EPR) spectroscopy, including spin trapping with carboxy-PTIO (cPTIO), demonstrated that 5 microM or less of arsenite did not increase *NO levels over a 30-min period relative to *NO release stimulated by bradykinin. However, these same levels of arsenite rapidly increased both oxygen consumption and superoxide formation, as measured by EPR oximetry and spin trapping with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), respectively. Pretreatment of the cells with DPI, apocynin, or superoxide dismutase abolished arsenite-stimulated DMPO-OH adduct formation. Finally arsenite increased extracellular accumulation of H2O2, measured as oxidation of homovanillic acid, with the same time and dose dependence, as seen for superoxide formation. These data suggest that superoxide and H2O2 are the predominant reactive species produced by endothelial cells after arsenite exposures that stimulate cell signaling and activate transcription factors.",
Arsenic,627064,"Tissue distribution and urinary excretion of inorganic arsenic and Its methylated metabolites in mice following acute oral administration of arsenate Abstract: The relationship of exposure dose and tissue concentration of parent chemical and metabolites is a critical issue in cases where toxicity may be mediated by a metabolite or by parent chemical and metabolite acting together. This has emerged as an issue for inorganic arsenic (iAs), because both its trivalent and pentavalent methylated metabolites have unique toxicities; the methylated trivalent metabolites also exhibit greater potency than trivalent inorganic arsenic (arsenite, As(III)) for some endpoints. In this study, the time-course tissue distributions for iAs and its methylated metabolites were determined in blood, liver, lung, and kidney of female B6C3F1 mice given a single oral dose of 0, 10, or 100 micromol As/kg (sodium arsenate, As(V)). Compared to other organs, blood concentrations of iAs, mono- (MMA), and dimethylated arsenic (DMA) were uniformly lower across both dose levels and time points. Liver and kidney concentrations of iAs were similar at both dose levels and peaked at 1 h post dosing. Inorganic As was the predominant arsenical in liver and kidney up to 1 and 2 h post dosing, with 10 and 100 micromol As/kg, respectively. At later times, DMA was the predominant metabolite in liver and kidney. By 1 h post dosing, concentrations of MMA in kidney were 3- to 4-fold higher compared to other tissues. Peak concentrations of DMA in kidney were achieved at 2 h post dosing for both dose levels. Notably, DMA was the predominant metabolite in lung at all time points following dosing with 10 micromol As/kg. DMA concentration in lung equaled or exceeded that of other tissues from 4 h post dosing onward for both dose levels. These data demonstrate distinct organ-specific differences in the distribution and methylation of iAs and its methylated metabolites after exposure to As(V) that should be considered when investigating mechanisms of arsenic-induced toxicity and carcinogenicity.",
Arsenic,2337282,"Improved performance of ?-amylase immobilized on poly(glycidyl methacrylate-co-ethylenedimethacrylate) beads Abstract: ?-Amylase was successfully immobilized onto poly(glycidyl methacrylate-co-ethylenedimethacrylate) (PGMA/EDMA) beads with high immobilization efficiency of 87.8%. PGMA/EDMA beads with a relatively uniform diameter of 2-3 ?m were prepared by single-step swelling polymerization. After amination with ethanediamine and activation with glutaraldehyde, PGMA/EDMA beads showed commendable ?-amylase immobilization capacity of 35.1 mg g(-1) carrier. Compared with free form, immobilized ?-amylase had increasement of 12.94 mg mL(-1) for Km and 0.124 mmol mL(-1) min(-1) for Vmax, improved acid resistance (the optimal pH from 7 to 5), presented better thermal stability by retaining 61% activity than 40% at 90 °C, and displayed high operational reusability by retaining 58% of its initial activity after nine uses. Moreover, less than 10% of the free enzyme and more than 80% of the immobilized enzyme retained activity after 180 min pre-incubation at 50 °C. The easy modification, high immobilization efficiency and good properties of immobilized ?-amylase in the present study indicate that PGMA/EDMA beads are suitable for ?-amylase immobilization. The enhancement of acid resistance and thermo stability is doubtless of benefit for the industrial use of ?-amylase.",
Arsenic,2278382,"Selenium biofortification in lentil (Lens culinaris Medikus subsp. culinaris): Farmers' field survey and genotype x environment effect Abstract: Selenium (Se) is an essential micronutrient for humans and animals, however more than one billion people around the world are Se deficient. Selenium helps to prevent several diseases in humans including arsenicosis, a major health problem in South Asia. Lentil is a popular staple food in South Asia; it can uptake Se from soil and is thus a potential source of Se for humans. A farmers' field survey and an on-station yield trial of seven advanced breeding lines at four locations were conducted in Bangladesh during 2010–11 to determine Se concentration in lentil. Total Se concentration was measured in soil and lentil seeds collected from both farmers' fields and yield trials. Mean of soil and lentil seed Se concentration in farmers' fields was 163 ?g kg? 1 and 312 ?g kg? 1, respectively, with the highest being 173 ?g kg? 1 and 370 ?g kg? 1 in Rajshahi division, a major lentil growing area in Bangladesh. Consumption of 50 g of lentil provides 28% of the recommended daily allowance of Se (55 ?g per person per day). There were significant genotype and location differences observed for seed Se, Se yield, and seed yield. However, genotype × location interaction was not significant for seed Se and Se yield, but was significant for seed yield. Soil Se concentration in lentil growing regions of Bangladesh was moderate and overall it produced Se-rich lentils. Therefore, Se biofortification in lentil using agronomic and/or genetic approaches are possible to increase Se intake for Se deficient populations.",
Arsenic,1508552,"The fate of arsenic, cadmium and lead in Typha latifolia: A case study on the applicability of micro-PIXE in plant ionomics Abstract: Understanding the uptake, accumulation and distribution of toxic elements in plants is crucial to the design of effective phytoremediation strategies, especially in the case of complex multi-element pollution. Using micro-proton induced X-ray emission, the spatial distribution of Na, Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, Zn, As, Br, Rb, Sr, Cd and Pb have been quantitatively resolved in roots and rhizomes of an obligate wetland plant species, Typha latifolia, treated with a mixture of 100?M each of As, Cd and Pb, together. The highest concentrations of As, Cd and Pb were found in the roots of the T. latifolia, with tissue-specific distributions. The As was detected in the root rhizodermis, and in the rhizome the majority of the As was within the vascular tissues, which indicates the high mobility of As within T. latifolia. The Cd was detected in the root exodermis, and in the vascular bundle and epidermis of the rhizome. The highest Pb concentrations were detected in the root rhizodermis and exodermis, and in the epidermis of the rhizome. These data represent an essential step in the resolution of fundamental questions in plant ionomics.",
Arsenic,628604,"Aberrant cytokeratin expression during arsenic-induced acquired malignant phenotype in human HaCaT keratinocytes consistent with epidermal carcinogenesis Abstract: Inorganic arsenic is a known human skin carcinogen. Chronic arsenic exposure results in various human skin lesions, including hyperkeratosis and squamous cell carcinoma (SCC), both characterized by distorted cytokeratin (CK) production. Prior work shows the human skin keratinocyte HaCaT cell line, when exposed chronically for >25 weeks to a low level of inorganic arsenite (100 nM) results in cells able to produce aggressive SCC upon inoculation into nude mice. In the present study, CK expression analysis was performed in arsenic-exposed HaCaT cells during the progressive acquisition of this malignant phenotype (0–20 weeks) to further validate this model as relevant to epidermal carcinogenesis induced by arsenic in humans. Indeed, we observed clear evidence of acquired cancer phenotype by 20 weeks of arsenite exposure including the formation of giant cells, a >4-fold increase in colony formation in soft agar and a not, vert, similar2.5-fold increase in matrix metalloproteinase-9 secretion, an enzyme often secreted by cancer cells to help invade through the local extra-cellular matrix. During this acquired malignant phenotype, various CK genes showed markedly altered expression at the transcript and protein levels in a time-dependent manner. For example, CK1, a marker of hyperkeratosis, increased up to 34-fold during arsenic-induced transformation, while CK13, a marker for dermal cancer progression, increased up to 45-fold. The stem cell marker, CK15, increased up to 7-fold, particularly during the later stages of arsenic exposure, indicating a potential emergence of cancer stem-like cells with arsenic-induced acquired malignant phenotype. The expression of involucrin and loricrin, markers for keratinocyte differentiation, increased up to 9-fold. Thus, during arsenic-induced acquired cancer phenotype in human keratinocytes, dramatic and dynamic alterations in CK expression occur which are consistent with the process of epidermal carcinogenesis helping validate this as an appropriate model for the study of arsenic-induced skin cancer.",
Arsenic,627863,"DNA hypermethylation of promoter of gene p53 and p16 in arsenic-exposed people with and without malignancy Abstract: Chronic arsenic exposure is known to produce arsenicosis and cancer. To ascertain whether perturbation of methylation plays a role in such carcinogenesis, the degree of methylation of p53 and p16 gene in DNA obtained from blood samples of people chronically exposed to arsenic and skin cancer subjects was studied. Methylation-specific restriction endonuclease digestion followed by polymerase chain reaction (PCR) of gene p53 and bisulfite treatment followed by methylation-sensitive PCR of gene p16 have been carried out to analyze the methylation status of the samples studied. Significant DNA hypermethylation of promoter region of p53 gene was observed in DNA of arsenic-exposed people compared to control subjects. This hypermethylation showed a dose-response relationship. Further, hypermethylation of p53 gene was also observed in arsenic-induced skin cancer patients compared to subjects having skin cancer unrelated to arsenic, though not at significant level. However, a small subgroup of cases showed hypomethylation with high arsenic exposure. Significant hypermethylation of gene p16 was also observed in cases of arsenicosis exposed to high level of arsenic. In man, arsenic has the ability to alter DNA methylation patterns in gene p53 and p16, which are important in carcinogenesis.",
Arsenic,627145,"Chronic exposure to methylated arsenicals stimulates arsenic excretion pathways and induces arsenic tolerance in rat liver cells Abstract: Although inorganic arsenicals are toxic and carcinogenic in humans, inorganic arsenite has recently emerged as a highly effective chemotherapeutic agent for acute promyelocytic leukemia (APL). Inorganic arsenicals are enzymatically methylated to monomethylarsonic acid (MMAs(V)), dimethylarsinic acid (DMAs(V)), and trimethylarsine oxide (TMAs(V)O) in mammals. We examined the effects of chronic exposure to methylated arsenicals on arsenic tolerance by using rat normal liver TRL 1215 cells. TRL 1215 cells were exposed for 20 weeks to MMAs(V), DMAs(V), or TMAs(V)O at levels that produced submicromolar cellular concentrations of arsenic. On chronic exposure to these methylated arsenicals, the cells acquired tolerance to acute arsenic cytolethality. Cellular arsenic uptake was reduced in these cells compared to passage-matched control cells. The long-term arsenic exposure increased glutathione S-transferase (GST) activity and cellular glutathione (GSH) levels. Glutathione S-transferase, multidrug resistance-associated proteins (Mrps; efflux transporters encoded by Mrp genes), and P-glycoprotein [P-gp; efflux transporter encoded by multidrug resistance gene (MDR)] had also increased in these cells at the transcript and protein levels. The depletion of cellular GSH and the inhibition of Mrps and P-gp functions increased cellular arsenic uptake and reduced arsenic tolerance in these cells. These results indicate that chronic exposure to methylated arsenicals induces a generalized arsenic tolerance that is caused by increased arsenic excretion. Because accumulation of methylated arsenicals may occur in patients with chronic arsenic poisoning and arsenic-treated APL patients, this study may provide important information regarding chronic arsenic poisoning and the latent risk of developing multidrug resistance in APL therapy using inorganic arsenite.",
Arsenic,1348439,"Assessment of hazardous mine waste transport in west central Sinai, using remote sensing and GIS approaches: a case study of Um Bogma area, Egypt Abstract: ",
Arsenic,2149372,Synchrotron-based spectroscopy reveals first evidence for organic sulfur-coordinated arsenic in peat Abstract: ,
Arsenic,1346376,Degradation and Removal of Sulfadiazine from Waters by a Novel Polymer-supported Hydrous Manganese Dioxide(HMO) Abstract: ,
Arsenic,627977,"Association between arsenic exposure from drinking water and plasma levels of soluble cell adhesion molecules Abstract: BACKGROUND: Epidemiologic studies of cardiovascular disease risk factors and appropriate biomarkers in populations exposed to a wide range of arsenic levels are a public health research priority. OBJECTIVE: We investigated the relationship between inorganic arsenic exposure from drinking water and plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular adhesion molecule-1 (sVCAM-1), both markers of endothelial dysfunction and vascular inflammation, in an arsenic-exposed population in Araihazar, Bangladesh. METHODS: The study participants included 115 individuals with arsenic-related skin lesions participating in a 2 x 2 randomized, placebo-controlled, double-blind trial of vitamin E and selenium supplementation. Arsenic exposure status and plasma levels of sICAM-1 and sVCAM-1 were assessed at baseline and after 6 months of follow-up. RESULTS: Baseline well arsenic, a long-term measure of arsenic exposure, was positively associated with baseline levels of both sICAM-1 and sVCAM-1 and with changes in the two markers over time. At baseline, for every 1 ?g/L increase in well arsenic there was an increase of 0.10 ng/mL [95% confidence interval (CI), 0.00-0.20] and 0.33 ng/mL (95% CI, 0.15-0.51) in plasma sICAM-1 and sVCAM-1, respectively. Every 1 ?g/L increase in well arsenic was associated with a rise of 0.11 ng/mL (95% CI, 0.01-0.22) and 0.17 ng/mL (95% CI, 0.00-0.35) in sICAM-1 and sVCAM-1 from baseline to follow-up, respectively, in spite of recent changes in urinary arsenic as well as vitamin E and selenium supplementation during the study period. CONCLUSIONS: The findings indicate an effect of chronic arsenic exposure from drinking water on vascular inflammation that persists over time and also suggest a potential mechanism underlying the association between arsenic exposure and cardiovascular disease.",
Arsenic,2298736,"Selective oxidation of arsenite by peroxymonosulfate with high utilization efficiency of oxidant Abstract: Oxidation of arsenite (As(III)) is a critical yet often weak link in many current technologies for remediating contaminated groundwater. We report a novel, efficient oxidation reaction for As(III) conversion to As(V) using commercial available peroxymonosulfate (PMS). As(III) is rapidly oxidized by PMS with a utilization efficiency larger than 90%. Increasing PMS concentrations and pH accelerate oxidation of As(III), independent to the availability of dissolved oxygen. The addition of PMS enables As(III) to oxidize completely to As(V) within 24 h, even in the presence of high concentrations of radical scavengers. On the basis of these observations and theoretical calculations, a two-electron transfer (i.e., oxygen atom transfer) reaction pathway is proposed. Direct oxidation of As(III) by PMS avoids the formation of nonselective reactive radicals, thus minimizing the adverse impact of coexisting organic matter and maximizing the utilization efficiency of PMS. Therefore, this simple approach is considered a cost-effective water treatment method for the oxidation of As(III) to As(V).",
Arsenic,1244043,"Anatomy and ultrastructure alterations of Leucaena leucocephala (Lam.) inoculated with mycorrhizal fungi in response to arsenic-contaminated soil Abstract: Many studies demonstrate the potential application of arbuscular mycorrhizal fungi (AMF) for remediation purposes, but little is known on AMF potential to enhance plant tolerance to arsenic (As) and the mechanisms involved in this process. We carried anatomical and ultrastructural studies to examine this symbiotic association and the characteristics of shoots and roots of Leucaena leucocephala in As-amended soils (35 and 75mgAsdm(-3)). The experiment used 3 AMF isolates from uncontaminated soils: Acaulospora morrowiae, Glomus clarum, and Gigaspora albida; a mixed inoculum derived from combining these 3 isolates (named Mix AMF); and, 3 AMF isolates from As-contaminated areas: A. morrowiae, G. clarum and Paraglomus occultum. Phytotoxicity symptoms due to arsenic contamination appeared during plant growth, especially in treatments without AMF application. Inoculation with G. clarum and the mixture of species (A. morrowiae, G. albida, and G. clarum) resulted in better growth of L. leucocephala in soils with high As concentrations, as well as significant As removal from the soil, showing a potential for using AMF in phytoextraction. Light microscopy (LS), transmission (TEM) and scanning electron microscopies (SEM) studies showed the colonization of the AMF in plant tissues and damage in all treatments, with ultrastructural changes being observed in leaves and roots of L. leucocephala, especially with the addition of 75mgdm(-3) of As.",
Arsenic,656644,"DNA repair deficiency leads to susceptibility to develop arsenic-induced premalignant skin lesions Abstract: In West Bengal, India, although more than 6 million people are exposed to arsenic through drinking water, only 15-20% showed arsenic-induced skin lesions, including premalignant hyperkeratosis. This indicates toward some factors that confer susceptibility to arsenic-induced carcinogenicity. In this work, we wanted to explore whether differences in DNA repair capacity could impart arsenic-induced carcinogenicity, through Comet assay, chromosomal aberration (CA) assay and challenge assay. Sixty arsenic exposed (30 individuals with arsenic-induced premalignant hyperkeratosis and 30 without skin lesion, but drinking similar arsenic contaminated water) and 30 arsenic unexposed individuals were recruited as study participants. Alkaline comet assay, and challenge assay were carried out in whole blood and CA study in lymphocytes to find out the DNA damage and DNA repair capacity in both hyperkeratotic and without skin lesion individuals. DNA damage as well as CA were found to be significantly higher in the arsenic-exposed individuals compared to unexposed individuals (p < 0.001). Within the exposed group, there was no significant difference as far as the level of DNA damage is concerned (p > 0.05), but CA was significantly higher in exposed individuals with hyperkeratosis than exposed individuals without hyperkeratosis (p < 0.01). Challenge assay showed that upon induction of DNA damage, the repair capacity in the exposed individuals with premalignant hyperkeratosis is significantly less (p < 0.001) than that of individuals without skin lesion, although the basal level of DNA damage was similar in both. Thus, the deficiency in DNA repair capacities in the hyperkeratotic individuals emerges as a prime contender for arsenic carcinogenicity.",
Arsenic,2345789,"Response of ammonia oxidizing microbes to the stresses of arsenic and copper in two acidic alfisols Abstract: Soil pollution by elevated heavy metals exhibits adverse effects on soil microorganisms. Ammonia oxidizing bacteria and ammonia oxidizing archaea perform ammonia oxidative processes in acidic soils. However, influence of heavy metal stress on soil ammonia oxidizers distribution and diversity is inadequately addressed. This study investigated the responses of ammonia oxidizing bacteria and archaea to heavy metals, Cu and As during short-term laboratory experiment. Two different acidic alfisols named as Rayka and Hangzhou spiked with different concentrations of As, Cu and As + Cu were incubated for 10 weeks. Significant reduction in copy numbers of archaeal-16S rRNA, bacterial-16S rRNA and functional amoA genes was observed along elevated heavy metal concentrations. Ammonia oxidizing archaea was found to be more abundant than ammonia oxidizing bacteria in all the heavy metal treatments. The potential nitrification rate significantly decreased with increasing As and Cu concentrations in the two soils examined. Denaturing gradient gel electrophoresis analysis revealed no apparent community shift for ammonia oxidizing archaea even at higher concentrations of As and Cu. Phylogenetic analysis of archaeal amoA gene from 4 clone libraries indicated that all the archaeal amoA sequences were placed within 3 distinct clusters from soil and sediment group 1.1b of Thaumarchaeota. Our results could be useful for the better understanding of the ecological effects of heavy metals on the abundance and diversity of soil ammonia oxidizers.(c) 2014 Elsevier B.V. All rights reserved.",
Arsenic,2337124,"OPTIMIZATION OF COD REMOVAL FROM POLYVINYL ALCOHOL AQUEOUS SOLUTION VIA ELECTROCOAGULATION USING RESPONSE SURFACE METHODOLOGY Abstract: We investigated the influence of experimental factors on the removal polyvinyl alcohol (PVA) in a batch reactor by electrocoagulation (EC) using response surface methodology (RSM). Central composite design (CCD) was used to evaluate influence of three operating factors of the response surface on the COD removal efficiency of PVA: current density, supporting electrolyte concentration, and temperature. Analysis of variance (ANOVA) showed a high coefficient of determination value (R-2) and an insignificant lack of fit for the quadratic response surface model. The current density was found to be more significant than the supporting electrolyte concentration and temperature. The optimal conditions to achieve over 90% COD removal efficiency were established as a current density of 7.05 mA/cm(2), a supporting electrolyte concentration of 0.012 N, and a temperature of 304.98 K. The experimental values agreed with the theoretical results very well, indicating that the models employed to optimize the EC removal of PVA were effective. The results show that process optimization using CCD was reliable and removed PVA at the desired performance level.",
Arsenic,1337596,Draft Genome Sequence of Achromobacter piechaudii Strain HLE Abstract: Achromobacter piechaudii strain HLE is a betaproteobacterium (previously known as Alcaligenes faecalis) that was an early isolate with arsenite oxidase activity. This draft genome of 6.89 Mb is the second available genome for this species in the opportunistic pathogen Alcaligenaceae family.,
Arsenic,1019960,"Effect of selenite on the disposition of arsenate and arsenite in rats Abstract: Selenite (SeIV) and inorganic arsenicals counter the toxicity of each other. SeIV inhibits arsenic methylation in hepatocytes, however, it is unknown whether it decreases the formation of the highly toxic monomethylarsonous acid (MMAsIII). Therefore, we examined, in comparison with the methylation inhibitor periodate-oxidised adenosine (PAD), the effect of SeIV (10 micromol/kg, i.v.) on the appearance of arsenic metabolites in blood, bile and urine as well as the distribution of arsenic metabolites in the liver and kidneys in rats injected i.v. with 50 micromol/kg arsenite (AsIII) or arsenate (AsV). Arsenic metabolites were analysed by HPLC-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). In rats given either arsenical, PAD decreased the excretion and tissue concentrations of methylated arsenic metabolites (MMAsIII, monomethylarsonic acid [MMAsV], and dimethylarsinic acid [DMAsV]), while increasing the tissue retention of AsV and AsIII. The effect of SeIV on arsenic disposition differed significantly from that of PAD. For example, both in AsIII- and AsV-injected animals, SeIV lowered the tissue levels of MMAsIII and MMAsV, but increased the levels of DMAsV. SeIV almost abolished the biliary excretion of MMAsIII in AsV-exposed rats, but barely influenced it in AsIII-dosed rats. The SeIV-induced changes in arsenic disposition may largely be ascribable to formation of the known complex containing trivalent arsenic and selenide (SeII), which not only depends on but also influences the availability and effects of these metalloid species in tissues. By such complexation SeII compromises monomethylation of arsenic when trivalent arsenic availability is limited (e.g. in AsV-exposed rats), but affects it less when the presence of AsIII is overwhelming (e.g. in AsIII-dosed rats). As an auxiliary finding, it is shown that DMAsV occurs in the blood of rats not injected with arsenic and that DMAsV formation in rats can be followed by measuring the build-up of blood-borne DMAsV.",
Arsenic,1246918,"Arsenic concentrations in dust emissions from wind erosion and off-road vehicles in the Nellis Dunes Recreational Area, Nevada, USA Abstract: Field and laboratory experiments were performed in the Nellis Dunes Recreational Area near Las Vegas, NV, USA to evaluate arsenic concentrations associated with dust emissions from wind erosion and off-road vehicles. Soil samples were collected from 17 types of desert surfaces and five unpaved parking lot locations for analyses. The surface units are based on surficial characteristics that affect dust emissions. Arsenic concentrations were also measured in dust emitted from each surface unit using a Portable In Situ Wind Erosion Laboratory (PI-SWERL). Emissions were measured from ORV trails and undisturbed terrain. Concentrations of As in the soil and parking lot samples ranged from 3.49 to 83.02 mu g g(-1) and from 16.13 to 312 mu g g(-1) in the PI-SWERL samples. The lower concentrations in the soil samples are expected because of the larger particle sizes (&lt;2 mm) as compared to the PI-SWERL samples (&lt;10 and 10-60 mu m). Soluble As in the PI-SWERL samples was as high as 14.7 mu g g(-1). In the Nellis Dunes area the emission rates for As for wind-induced emissions (wind erosion) are highest for the surfaces with significant amounts of sand. Surfaces rich in silt and clay, on the other hand, produce nearly no arsenic during wind erosion but can emit substantial arsenic concentrations when driven on by off-road vehicles. The elevated arsenic emissions from the Nellis Dunes area are of great concern because the site is located in the immediate vicinity of the city of Las Vegas, and utilized by over 300,000 visitors annually. (c) 2011 Elsevier B.V. All rights reserved.",
Arsenic,2337165,"High fluorine and other associated trace elements in waters from the south of the Pampean plain Abstract: We investigated the levels of F and its relationship with As, B and V in ground and surface waters of the southern Pampas, where cases of dental and skeletal fluorosis, and arsenic in hair and urine samples have been detected in the rural population. Eating vegetables and cereals grown in irrigated areas with excessive fluoride may increase the risk of fluorosis due to the addition of the extra F contributed from other sources such as drinking water. Moreover, if these elements exceed the tolerance of crops produce toxicity and, like salinity, they decrease the potential crop yield. Within an area of 2300 km(2), 81 samples were taken from surface and groundwaters to determine F, As, B and V. Fluoride was detected in 86% of the sampled groundwaters, and in 65% of the surface waters reaching maximun concentrations of 7.12 mg/L and of 6.5 mg/L, respectively. Risk areas were determined based on the distribution of F in the unconfined aquifer; the highest concentrations were observed towards the S-SW, in the central and SE sectors. On the surface flow, the highest concentrations were found at the west with sampling points remarkably prominent. These waters are classified as sodium-sulfate, 03 and with high concentrations of F, B and V that could produce toxicity and reduce yields on irrigated crops. Fluoride correlated significantly (p&lt;0.01) with As (1,0.75), B (r=0.57) and V (r=0.53) in groundwater; it also associated with As (r = 0.65) in surface waters, and showed higher levels of association with boron (r=0.88) and vanadium (r=0.81), which showed highly significant linear regressions (p&lt;0.01).",
Arsenic,1936193,"Calcite Surface Adsorption of As(V), As(III), MMAs(V), and DMAs(V) and the Impact of Calcium and Phosphate Abstract: ",
Arsenic,1936181,"Procedia Earth and Plantetary Science Geochemistry of high arsenic groundwaters in the Yinchuan basin, PR China Abstract: ",
Arsenic,2345671,"Spatial Distribution of Mercury and Arsenic Levels in Water, Soil and Cassava Plants in a Community with Long History of Gold Mining in Tanzania Abstract: This study examined the spatial distribution of total mercury (THg) and total arsenic (TAs) in water, soil and cassava (Manihot esculenta) (leaves and roots) samples taken from areas in Rwamagasa village in northwestern Tanzania where daily living activities occur in close proximity to extensive artisanal and small scale gold mining. Results indicated that 33.3 % of the water sources had THg levels above the WHO guideline of 1.0 µg/L for safe drinking water, and 12.5 % had TAs levels above 10 µg/L. Cassava leaves were found to have higher THg (ranging from 8.3 to 167 µg/kg) and TAs (ranging from 60 to 1,120 µg/kg) levels than cassava roots, which ranged between 1.2-8.3 µg/kg for THg and 25-310 µg/kg for TAs. Concentrations of THg and TAs in soil samples ranged between 5.8-1,759 and 183-20,298 µg/kg, respectively. Both THg and TAs were found to be distributed throughout Rwamagasa village.",
Arsenic,2343475,"Synergistic cytotoxicity and DNA strand breaks in cells and plasmid DNA exposed to uranyl acetate and ultraviolet radiation Abstract: Depleted uranium (DU) has a chemical toxicity that is independent of its radioactivity. The purpose of this study was to explore the photoactivation of uranyl ion by ultraviolet (UV) radiation as a chemical mechanism of uranium genotoxicity. The ability of UVB (302?nm) and UVA (368?nm) radiation to photoactivate uranyl ion to produce single strand breaks was measured in pBR322 plasmid DNA, and the presence of adducts and apurinic/apyrimidinic sites that could be converted to single strand breaks by heat and piperidine was analyzed. Results showed that DNA lesions in plasmid DNA exposed to UVB- or UVA-activated DU were only slightly heat reactive, but were piperidine sensitive. The cytotoxicity of UVB-activated uranyl ion was measured in repair-proficient and repair-deficient Chinese hamster ovary cells and human keratinocyte HaCaT cells. The cytotoxicity of co-exposures of uranyl ion and UVB radiation was dependent on the order of exposure and was greater than co-exposures of arsenite and UVB radiation. Uranyl ion and UVB radiation were synergistically cytotoxic in cells, and cells exposed to photoactivated DU required different DNA repair pathways than cells exposed to non-photoactivated DU. This study contributes to our understanding of the DNA lesions formed by DU, as well as their repair. Results suggest that excitation of uranyl ion by UV radiation can provide a pathway for uranyl ion to be chemically genotoxic in populations with dermal exposures to uranium and UV radiation, which would make skin an overlooked target organ for uranium exposures. Copyright © 2014 John Wiley &amp; Sons, Ltd.",
Arsenic,1028393,Arsenical encephalopathy treated with B. A. L Abstract: ,
Arsenic,1018733,"Significance of exposure assessment to analysis of cancer risk from inorganic arsenic in drinking water in Taiwan Abstract: The primary source of evidence that inorganic arsenic in drinking water is associated with increased mortality from cancer at internal sites (bladder, liver, lung, and other organs) is a large ecologic study conducted in regions of Southwest Taiwan endemic to Blackfoot disease. The dose-response patterns for lung, liver, and bladder cancers display a nonlinear dose-response relationship with arsenic exposure. The data do not appear suitable, however, for the more refined task of dose-response assessment, particularly for inference of risk at the low arsenic concentrations found in some U.S. water supplies. The problem lies in variable arsenic concentrations between the wells within a village, largely due to a mix of shallow wells and deep artesian wells, and in having only one well test for 24 (40%) of the 60 villages. The current analysis identifies 14 villages where the exposure appears most questionable, based on criteria described in the text. The exposure values were then changed for seven of the villages, from the median well test being used as a default to some other point in the village's range of well tests that would contribute to smoothing the appearance of a dose-response curve. The remaining seven villages, six of which had only one well test, were deleted as outliers. The resultant dose-response patterns showed no evidence of excess risk below arsenic concentrations of 0.1 mg/l. Of course, that outcome is dependent on manipulation of the data, as described. Inclusion of the seven deleted villages would make estimates of risk much higher at low doses. In those seven villages, the cancer mortality rates are significantly high for their exposure levels, suggesting that their exposure values may be too low or that other etiological factors need to be taken into account.",
Arsenic,1032439,"Enhancement of glutathione levels in mouse peritoneal macrophages by sodium arsenite, cadmium chloride and glucose/glucose oxidase Abstract: Glutathione content of mouse peritoneal macrophages markedly increased when they were exposed to insulting agents like sodium arsenite, cadmium chloride, and glucose/glucose oxidase which generates hydrogen peroxide. This increase was attributed to the induction of the cystine transport activity by these agents. The transport activity for other amino acids was not induced, but rather diminished by these agents. Heat shock treatment did not induce the cystine transport activity, nor did it augment glutathione. Since glutathione protects cells against the cytotoxic effects of these agents, the induction of the cystine transport activity constitutes a protective mechanism related to the stress caused by the agents. The protein component(s) for cystine transport may fall into the category of the stress protein.",
Arsenic,1342735,"Uptake and speciation of inorganic arsenic with cellulose fibre coated with yttrium hydroxide layer as a novel green sorbent Abstract: A novel adsorbent was developed by coating yttrium hydroxide precipitate layer on cellulose fibre. This material takes up ca. 98% of 5 µg·L?1 As(III) and As(V) at low pH (pH<7), while a favorable selectivity for As(V) was achieved within pH 11–12. In practice, a mini-column packed with Y(OH)3 precipitate layer coated cellulose fibre particles was incorporated into a sequential injection system for selective uptake of arsenate at pH 11.5. The retained arsenate was afterwards recovered with 50 µL of 0.8 mol·L?1 NaOH solution as eluent, followed by hydride generation in a reaction medium of 2.0 mol·L?1 HCl and 1.0% NaBH4 solution (W/V, in 0.5% NaOH) after pre-reduction of arsenate to arsenite by KI-ascorbic acid (5%, W/V), with detection by atomic fluorescence spectrometry. Total inorganic arsenic was quantitatively taken up at pH 6.0 by following the same procedure and arsenic speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 16.4 was derived with a detection limit of 17 ng·L?1 within a linear range of 0.05–2.0 µg·L?1. A relative standard deviation (RSD) of 2.6% (0.5 µg·L?1, n=11) was achieved. The procedure was validated by analyzing arsenic in a certified reference material GBW 09101 (human hair), and speciation of inorganic arsenic in natural water samples. The entire process requires no organic solvents, thus Y(OH)3 coated cellulose fibre provides a green adsorbent.",
Arsenic,1508591,"Sorption of As(III) and As(V) on chemically synthesized manganese dioxide Abstract: Sorption of As(III) and As(V) on manganese dioxide was studied by batch equilibration method using (76)As radioactive tracer. Manganese dioxide was prepared by two different methods viz. reacting (a) KMnO(4) solution with MnSO(4) solution, and (b) KMnO(4) solution with concentrated hydrochloric acid. Manganese dioxide was characterized by zeta potential measurement, surface area measurement, thermogravimetry (TG), differential thermal analysis (DTA) and X-ray diffraction (XRD) techniques. Point of zero charge (PZC) for manganese dioxide was between pH 3 and 4. Radioactive tracer ((76)As) was prepared by neutron irradiation of arsenious oxide in self serve facility of CIRUS reactor followed by conversion to As(III) and As(V), by appropriate chemical methods. Sorption of As(III) and As(V) were studied separately, between pH 1 to 11, using (i) freshly prepared, (ii) air-dried and (iii) aged manganese dioxide. Sorption of As(III) and As(V) on freshly prepared as well as aged manganese dioxide, from both the methods was greater than 98% between pH 1 to 9 and decreased above pH 9. Percentage sorption was comparable for manganese dioxide prepared by both the methods in different batches. Sorption capacity was ?2 mg g(-1) for both As(III) and As(V). Arsenic was desorbed from the manganese dioxide by 0.1 M sodium hydroxide and oxidation state of desorbed arsenic was determined by solvent extraction method. It was found that the desorbed arsenic was present in As(V) oxidation state, independent of the initial oxidation states. This simple and direct chemical evidence, establishing that As(III) is converted to As(V) by manganese dioxide, is reported for the first time. Sorption of As(III) and As(V) on manganese dioxide did not cause an increase in manganese concentration above solubility limit confirming that Mn(2+), formed during oxidation of As(III) to As(V), was re-adsorbed.",
Arsenic,109576,"Selenium Modifies the Metabolism and Toxicity of Arsenic in Primary Rat Hepatocytes Abstract: Arsenic and selenium are metalloids with similar chemical properties and metabolic fates. Inorganic arsenic (iAs) has been shown to modify metabolism and toxicity of inorganic and organic selenium compounds. However, little is known about effects of selenium on metabolism and toxicity of iAs. The present work examines the effects of selenite (Se(IV)) on the cellular retention, methylation, and cytotoxicity of trivalent iAs, arsenite (iAs(III)), in primary cultures of rat hepatocytes. The concurrent exposure to Se(IV) (0.1 to 6 microM) inhibited methylation and/or significantly increased cellular retention of iAs(III) in cultured cells. The ratio of the methylated metabolites produced from iAs(III), dimethylarsenic (DMAs) to methylarsenic (MAs), decreased considerably in cells treated with Se(IV), suggesting that synthesis of DMAs from MAs may be more susceptible to inhibition by Se(IV) than is the production of MAs from iAs(III). The 24-h preexposure to 2 microM Se(IV) had a similar but less pronounced inhibitory effect on the methylation of iAs(III) in cultured cells. The exposure to 2 microM Se(IV) alone for up to 24 h had no effect on the viability of cultured hepatocytes. However, concurrent exposure to 2 microM Se(IV) increased the cytotoxicity of iAs(III) and its mono- and dimethylated metabolites that contain trivalent arsenic, MAs(III) and DMAs(III). These data suggest that pre- or coexposure to inorganic selenium may enhance the toxic effects of iAs, increasing its retention in tissues and suppressing its methylation, which may be a pathway for detoxification of iAs.",
Arsenic,1350126,"Polymorphisms in GSTT1 and GSTM1, arsenic exposure, and skin lesions in Pabna, Bangladesh Abstract: Introduction: The study objective was to determine whether polymorphisms in GSTM1, and GSTT1 modify the association between exposure to arsenic through drinking water and the development of skin lesions such as hyperkeratosis and melanosis. To investigate whether metabolic polymorphisms in GSTM1, and GSTT1 and modify toenail arsenic level concentrations. Methods: 1200 subjects stratified on gender and age were recruited in a case control study in Pabna, Bangladesh. Subjects were collected 1:1 ratio of cases and controls. Questionnaire data, a water sample and toenail samples were collected on all subjects. Water samples were analyzed by ICP-MS EPA method 200.8. Toenail arsenic concentration was determined by ICP-MS. Results: Non-null GSTT1 was protective in modifying the risk of developing skin lesions given arsenic exposure (p=0.01). Toenail and water samples were highly correlated. Toenail arsenic levels were not modified by polymorphisms in GSTM1 or GSTT1. GSTM1 polymorphisms do not significantly modify the risk between arsenic exposure and skin lesions. Discussion: Polymorphisms in GSTT1 may influence the risk of arsenic-induced skin lesions.",
Arsenic,1936191,"Facile one-pot synthesis of lepidocrocite (gamma-FeOOH) nanoflakes for water treatment Abstract: Lepidocrocite (gamma-FeOOH) nanoflakes were synthesized using a simple ethylene glycol (EG) mediated solution method. The obtained gamma-FeOOH were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The absoption properties of the as-prepared gamma-FeOOH nanoflakes towards toxic As(V) and Cr(VI) ions were investigated. The effects of anions such as Cl-, SO42-, NO3-, HCO3-, CO32-, and PO43- on As(V) removal were also investigated. The results indicated that phosphate was the greatest competitor with As(V) for adsorptive sites. The presence of Cl-, SO42-, and NO3- had no effect on As(V) removal.",
Arsenic,628563,"Association of blood arsenic levels with increased reactive oxidants and decreased antioxidant capacity in a human population of northeastern Taiwan Abstract: Arsenic is a notorious environmental toxicant known as both a carcinogen and an atherogen in human beings, but the pathogenic mechanisms are not completely understood. In cell culture studies, trivalent arsenic enhanced oxidative stress in a variety of mammalian cells, and this association may be closely associated with the development of arsenic-related diseases. To investigate the effect of arsenic exposure on oxidative stress in humans, we conducted a population study to determine the relationships of blood arsenic to reactive oxidants and antioxidant capacity at the individual level. We recruited 64 study subjects ages 42-75 years from residents of the Lanyang Basin on the northeast coast of Taiwan, where arsenic content in well water varies from 0 to > or = 3,000 microg/L. We used a chemiluminescence method, with lucigenin as an amplifier for measuring superoxide, to measure the plasma level of reactive oxidants. We used the azino-diethyl-benzthiazoline sulphate method to determine the antioxidant capacity level in plasma of each study subject. We determined arsenic concentration in whole blood by hydride formation with an atomic absorption spectrophotometer. The average arsenic concentration in whole blood of study subjects was 9.60 +/- 9.96 microg/L (+/- SD) with a range from 0 to 46.50 microg/L. The level of arsenic concentration in whole blood of study subjects showed a positive association with the level of reactive oxidants in plasma (r = +0.41, p = 0.001) and an inverse relationship with the level of plasma antioxidant capacity (r = -0.30, p = 0.014). However, we found no significant association (p = 0.266) between levels of plasma reactive oxidants and antioxidant capacity. Our results also show that the lower the primary arsenic methylation capability, the lower the level of plasma antioxidant capacity (p = 0.029). These results suggest that ingestion of arsenic-contaminated well water may cause deleterious effects by increasing the level of reactive oxidants and decreasing the level of antioxidant capacity in plasma of individuals. Persistent oxidative stress in peripheral blood may be a mechanism underlying the carcinogenesis and atherosclerosis induced by long-term arsenic exposure.",
Arsenic,1337383,"Low concentration of arsenic-induced aberrant mitosis in keratinocytes through E2F1 transcriptionally regulated Aurora-A Abstract: Chronic exposure to low concentration arsenic promotes cell proliferation and carcinogenesis both in vitro and in vivo. Centrosome amplification, the major cause of chromosome instability, occurs frequently in cancers. Aurora-A is a mitotic kinase and causes centrosome amplification and chromosome instability when overexpressed. Our previous study revealed that low concentration arsenic induces Aurora-A overexpression in immortalized bladder cells. In this study, we hypothesized that low concentration arsenic induces aberrant mitosis in keratinocytes due to Aurora-A overexpression. The specimen of Bowen's disease (BD) and squamous cell carcinoma obtained from arseniasis-endemic areas in Taiwan showed Aurora-A overexpression. The mRNA/protein levels and kinase activity of Aurora-A were increased in immortalized keratinocyte HaCaT cells after arsenic treatment at low concentration (&lt;1?M). Aberrant spindles, multiple centrosomes and multinucleated cells were detected under fluorescent microscopy in HaCaT cells after arsenic treatment. These findings were associated with increased expression of Aurora-A. We further revealed that Aurora-A was regulated by arsenic-induced transcriptional factor E2F1 as demonstrated by chromosome immunoprecipitation, promoter activity and small interfering RNA assays. Finally, in arsenic-treated HaCaT cells and in BD, a significant increase of dysfunctional p53 was found, and this event correlated with the increase expression of Aurora-A. Altogether, our data suggest that low concentration of arsenic induces activation of E2F1-Aurora-A axis and results in aberrant mitosis of keratinocytes. Overexpression of Aurora-A and dysfunctional p53 may act synergistically to trigger skin tumor formation. Our findings suggest that Aurora-A may be a potential target for the prevention and treatment of arsenic-related cancers.",
Arsenic,627688,"Effects of arsenic on human keratinocytes: Morphological, physiological, and precursor incorporation studies Abstract: Measurement of in vitro percutaneous absorption of As(III) and As(V) by artificial human skin shows a strong affinity of arsenic for the human keratinocytes, with 1-10% of the applied arsenic dose retained by the artificial skin per hour. The inordinate retention of arsenic by the skin is a risk factor for As toxicity. The calculated permeability constant (K(p)) averaged about 4.3 x 10(-5) cm/h for As(V) and 10.1 x 10(-5) cm/h for As(III). A facile calculation suggests that dermal absorption during showering and hand washing can be an important exposure route if the water contains more than 100 microg/L As(III) or As(V). The effects of the absorbed arsenic in artificial skin were evaluated in terms of morphological characteristics, integrity of the cell membrane (by means of lactate dehydrogenase and MTS assays), and rates of DNA, RNA, and protein synthesis estimated by incorporation of radioactive precursors. We found significant morphological changes, cytotoxicity associated with disruption of the cell membrane, and inhibition of DNA and protein syntheses at As(III) exposure doses as low as 10 microg/L.",
Arsenic,1022113,"Investigation of occupational and environmental causes of respiratory cancers (ICARE): A multicenter, population-based case-control study in France Abstract: <strong>BACKGROUND: </strong>Occupational causes of respiratory cancers need to be further investigated: the role of occupational exposures in the aetiology of head and neck cancers remains largely unknown, and there are still substantial uncertainties for a number of suspected lung carcinogens. The main objective of the study is to examine occupational risk factors for lung and head and neck cancers.<br /><br /><strong>METHODS/DESIGN: </strong>ICARE is a multi-center, population-based case-control study, which included a group of 2926 lung cancer cases, a group of 2415 head and neck cancer cases, and a common control group of 3555 subjects. Incident cases were identified in collaboration with cancer registries, in 10 geographical areas. The control group was a random sample of the population of these areas, with a distribution by sex and age comparable to that of the cases, and a distribution by socioeconomic status comparable to that of the population. Subjects were interviewed face to face, using a standardized questionnaire collecting particularly information on tobacco and alcohol consumption, residential history and a detailed description of occupational history. Biological samples were also collected from study subjects. The main occupational exposures of interest are asbestos, man-made mineral fibers, formaldehyde, polycyclic aromatic hydrocarbons, chromium and nickel compounds, arsenic, wood dust, textile dust, solvents, strong acids, cutting fluids, silica, diesel fumes, welding fumes. The complete list of exposures of interest includes more than 60 substances. Occupational exposure assessment will use several complementary methods: case-by-case evaluation of exposure by experts; development and use of algorithms to assess exposure from the questionnaires; application of job-exposure matrices.<br /><br /><strong>DISCUSSION: </strong>The large number of subjects should allow to uncover exposures associated with moderate increase in risks, and to evaluate risks associated with infrequent or widely dispersed exposures. It will be possible to study joint effects of exposure to different occupational risk factors, to examine the interactions between occupational exposures, tobacco smoking, alcohol drinking, and genetic risk factors, and to estimate the proportion of respiratory cancers attributable to occupational exposures in France. In addition, information on many non-occupational risk factors is available, and the study will provide an excellent framework for numerous studies in various fields.",
Arsenic,2088562,"Microscale Speciation of Arsenic and Iron in Ferric-Based Sorbents Subjected to Simulated Landfill Conditions Abstract: During treatment for potable use, water utilities generate arsenic-bearing ferric wastes that are subsequently dispatched to landfills. The biogeochemical weathering of these residuals in mature landfills affects the potential mobilization of sorbed arsenic species via desorption from solids subjected to phase transformations driven by abundant organic matter and bacterial activity. Such processes are not simulated with the toxicity characteristic leaching procedure (TCLP) currently used to characterize hazard. To examine the effect of sulfate on As retention in landfill leachate, columns of As(V) loaded amorphous ferric hydroxide were reacted biotically at two leachate sulfate concentrations (0.064 mM and 2.1 mM). After 300 days, ferric sorbents were reductively dissolved. Arsenic released to porewaters was partially coprecipitated in mixed-valent secondary iron phases whose speciation was dependent on sulfate concentration. As and Fe XAS showed that, in the low sulfate column, 75-81% of As(V) was reduced to As(III), and 53-68% of the Fe(III) sorbent was transformed, dominantly to siderite and green rust. In the high sulfate column, Fe(III) solids were reduced principally to FeS(am), whereas As(V) was reduced to a polymeric sulfide with local atomic structure of realgar. Multienergy micro-X-ray fluorescence (ME-?XRF) imaging at Fe and As K-edges showed that As formed surface complexes with ferrihydrite &gt; siderite &gt; green rust in the low sulfate column; while discrete realgar-like phases formed in the high sulfate systems. Results indicate that landfill sulfur chemistry exerts strong control over the potential mobilization of As from ferric sorbent residuals by controlling secondary As and Fe sulfide coprecipitate formation.",
Arsenic,1017473,"Accumulation, biotransformation, and biochemical responses after exposure to arsenite and arsenate in the estuarine polychaete Laeonereis acuta (Nereididae) Abstract: <strong>INTRODUCTION: </strong>This study aimed to analyze antioxidant responses and oxidative damage induced by two inorganic forms of arsenic (As; As(III) and As(V)) in an estuarine polychaete species, Laeonereis acuta (Nereididae). The capacity of arsenic biotransformation was also evaluated through the methylation process considering the activity of a key enzyme involved in the metabolization process.<br /><br /><strong>MATERIALS AND METHODS: </strong>Worms were exposed to 50 ?g (As(III) or As(V))/l during 2 or 7 days, plus a control group. Endpoints analyzed included concentration of reactive oxygen species (ROS), activities of antioxidant enzymes such as glutathione reductase (GR), total glutathione-S-transferase (GST), and omega isoform (GST ?), glucose-6-phosphate deshydrogenase (G6PDH), levels of the antioxidant glutathione (GSH), and lipid peroxides concentration (TBARS).<br /><br /><strong>RESULTS AND DISCUSSION: </strong>Results showed: (1) GR inhibition after 2-day exposure to both As forms (p?&lt;?0.05); (2) GST ? inhibition after 7-day exposure to As(III) paralleled by an increase in total GST activity (p?&lt;?0.05); (3) augmented G6PDH activity after 7-day exposure to both As forms (p?&lt;?0.05); (4) no differences in terms of ROS and TBARS; and (5) inhibition of GST ? activity in As(III) exposed worms, which was concomitant with a lowering of mono- and dymethylated arsenic species.<br /><br /><strong>CONCLUSION: </strong>These results confirm the reactivity of some biochemical variables of L. acuta to As and indicates its importance as a sentinel species in estuarine regions with presence of arsenic.",
Arsenic,202046,"Arsenic, cadmium and lead levels in hair and toenail samples in Pakistan Abstract: We collected toenail and hair samples from 160 subjects, 83 males and 77 females, residing in Lahore city and its suburban areas in Pakistan, and examined the concentrations of arsenic, cadmium, lead and other metals using inductively coupled plasma mass spectrometry (ICP-MS). The mean hair and toenail arsenic levels were 0.31 ppm and 0.70 ppm, respectively. The correlation coefficient between log-transformed values of hair and toenail arsenic levels was 0.16 (p=0.051). After excluding a subject with hair and toenail arsenic levels as high as 1.12 ppm and 4.72 ppm, respectively, the correlation coefficient was 0.27 (p=0.001). Arsenic levels observed in the present study were relatively higher than in most developed countries. Hair or toenail arsenic concentration was not affected by sex, area of origin, place of residence and education, but toenail arsenic levels increased with age (p=0.029). Fish consumption was inversely related to arsenic levels, suggesting that consumption of beans , which are the main staple of poor people living in the study area who cannot afford to eat fish frequently, may be the source of arsenic exposure among the residents of Lahore and its suburban areas. The mean hair and toenail cadmium levels in the present study were 0.08 ppm and 0.05 ppm, respectively. The correlation coefficient between log-transformed values of hair and toenail cadmium levels was 0.17 (p=0.034). Cadmium levels were lower compared to those reported from developed countries, including Japan. The mean hair and toenail lead levels were 3.53 ppm and 2.11 ppm, respectively. The correlation coefficient between log-transformed values of hair and toenail lead levels was 0.15, which was not statistically significant (p=0.055). When a female subject with toenail lead of 52.4 ppm was excluded, the correlation was 0.17 (p=0.036). Lead levels observed in the present study were similar to those reported from developed countries. In the present study, relatively high lead toenail values were observed among children. The levels of cadmium and lead in hair but not in toenails were higher among those living in central Lahore than among those living outside Lahore, suggesting that dust containing those heavy metals was attached to hair samples due to a typical urban environment with heavy traffic load, congested population and industrial activities.",
Arsenic,657183,"Micronuclei assessment in buccal cells of people environmentally exposed to arsenic in northern Chile Abstract: To determine the genotoxic risk associated to environmental arsenic exposure, the frequency of micronuclei in buccal cells (BCMN) of people drinking arsenic-contaminated water has been evaluated. A group of 105 individuals from the Antofagasta region (north Chile), and 102 individuals from the area of Concepcion, used as reference group, were included in the study. Arsenic concentration in drinking water was high (0.75 mg/L) in the Antofagasta area, 75-fold the maximum recommended level by WHO (0.01 mg/L), while the values obtained in Concepcion were significantly lower (0.002 mg/L). Individual measures of arsenic exposure were also determined in fingernails, which clearly confirm the existence of chronic exposure in the sampled populations from the Antofagasta region (10.15 microg/g versus 3.57 microg/g). The cytogenetic results indicate that, although the BCMN frequency is higher in exposed than in controls, this increase does not attain statistical significance. When the exposure biomarkers were related with the cytogenetic values, no correlations were observed between BCMN and arsenic content in water or in fingernails. In addition, the genotoxicity values do not seem to be related to the ethnic origin from people belonging to the exposed group. As a conclusion it appears that, in the studied population, the chronic ingestion of arsenic-contaminated water does not induce cytogenetic damage, measured as micronuclei, in the cells of the oral mucous in a significant extent.",
Arsenic,735078,"Sodium arsenite-induced DAPK promoter hypermethylation and autophagy via ERK1/2 phosphorylation in human uroepithelial cells Abstract: Arsenic compounds or arsenicals are well-known toxic and carcinogenic agents. The toxic effects of arsenic that are of most concern to humans are those that occur from chronic, low-level exposure, and are associated with various human malignancies, including skin, lung and bladder cancers. In addition, arsenic could induce cell death, including apoptosis or autophagy in malignant cells. Previously, we have demonstrated that arsenite can induce autophagy and death-associated protein kinase (DAPK) promoter hypermethylation in the SV-40 immortalized human uroepithelial cell line (SV-HUC-1). However, the underlying mechanism of arsenite-induced autophagy is still unclear. In the present study, we demonstrate that arsenite can activate the extracellular signaling-regulated protein kinase 1/2 (ERK1/2) signaling pathway after treatment in SV-HUC-1 cells by using immunocytochemistry and Western blotting. In addition, our results also show an increase of autophagosomes was produced in arsenite-treated SV-HUC-1 cells by using electron microscopy. We found that, by incrementally increasing the dosages, microtubule-associated protein light chain 3B (LC3B) and Beclin-1 are important regulators for the formation of autophagosomes, in a dose-dependent manner. When the cells were pretreated with inhibitors 5-aza-CdR or U0126 for 24h, the effect of arsenite on ERK1/2, LC3B, Beclin-1 and DAPK proteins expression is suppressed. Furthermore, our results support the notion that arsenite can induce the ERK1/2 signaling pathway to stimulate autophagy and DAPK promoter hypermethylation in human uroepithelial SV-HUC-1 cells. These findings may contribute to a better understanding of the carcinogenesis of arsenite.",
Arsenic,1508577,"NF-?B1 p50 promotes p53 protein translation through miR-190 downregulation of PHLPP1 Abstract: The biological function of NF-?B1 (p50) in the regulation of protein expression is far from well understood owing to the lack of a transcriptional domain. Here, we report a novel function of p50 in its regulation of p53 protein translation under stress conditions. We found that the deletion of p50 (p50-/-) impaired arsenite-induced p53 protein expression, which could be restored after reconstitutive expression of HA-p50 in p50-/- cells, p50-/-(Ad-HA-p50). Further studies indicated that the amounts of p53 mRNA, p53 promoter-driven transcription activity and p53 protein degradation were comparable between wild-type and p50-/- cells. Moreover, we found that p50 was crucial for Akt/S6 ribosomal protein activation via inhibition of the translation of the PH domain and leucine-rich repeat protein phosphatases 1 (PHLPP1), a phosphatase of Akt. Further studies showed that p50-mediated upregulation of miR-190 was responsible for the inhibition of PHLPP1 translation by targeting the 3'-untranslated region of its mRNA. Collectively, we have identified a novel function of p50 in modulating p53 protein translation via regulation of the miR-190/PHLPP1/Akt-S6 ribosomal protein pathway.Oncogene advance online publication, 11 February 2013; doi:10.1038/onc.2013.8.",
Arsenic,2278641,"Immobilization of phosphorus, copper, zinc and arsenic in swine manure by activated red mud Abstract: Red mud (RM), the solid waste of alumina industry, is high in silicon, calcium, aluminum and iron oxides. In this study, RM was activated by heat treatment at different temperatures and characterized with BET nitrogen gas sorption, scanning electron microscopy analysis and X-ray diffraction analysis. Immobilization of phosphorus, copper, zinc, and arsenic in swine manure by activated RM was studied as a function of RM dosage, pH and time. The immobilization efficiency of phosphorus, copper, zinc and arsenic increased with the increase in RM dosage, reaching 77, 39, 42, and 78 % when the proportion of RM to swine manure was 20 %. The pH of the solution had a significant impact on the immobilization and it was found that the efficiency increased with the increase in pH. During the 24-h immobilization, the efficiency increased with time and achieved equilibrium after 12 h. Chemical variations of phosphorus, copper, zinc, and arsenic during the immobilization process were investigated with sequential chemical extraction method and the results showed that the contents of non-labile fractions of phosphorus, heavy metals and arsenic increased obviously, whereas the contents of labile fractions decreased.",
Arsenic,627369,"A new metabolic pathway of arsenite: Arsenic-glutathione complexes are substrates for human arsenic methyltransferase Cyt19 Abstract: The metabolism of arsenic is generally accepted to proceed by repetitive reduction and oxidative methylation; the latter is mediated by arsenic methyltransferase (Cyt19). In human urine, the major metabolites of inorganic arsenicals such as arsenite (iAsIII) and arsenate (iAsV) are monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)). On the other hand, in rat bile, the major metabolites of iAsIII have been reported to be arsenic-glutathione (As-GSH) complexes. In the present study we investigate whether these As-GSH complexes are substrates for arsenic methyltransferase by using human recombinant Cyt19. Analyses by high-performance liquid chromatography-inductively coupled plasma mass spectrometry suggested that arsenic triglutathione (ATG) was generated nonenzymatically from iAsIII when GSH was present at concentrations 2 mM or higher. Human recombinant Cyt19 catalyzed transfer of a methyl group from S-adenosyl-L-methionine to arsenic and produced monomethyl and dimethyl arsenicals. The methylation of arsenic was catalyzed by Cyt19 only when ATG was present in the reaction mixture. Moreover, monomethylarsonic diglutathione (MADG) was a substrate of Cyt19 for further methylation to dimethylarsinic glutathione (DMAG). On the other hand, monomethylarsonous acid (MMA(III)), a hydrolysis product of MADG, was not methylated to dimethyl arsenical by Cyt19. These results suggest that As-GSH complexes such as ATG and MADG were converted by Cyt19 to MADG and DMAG, respectively. Both MADG and DMAG were unstable in solution when the GSH concentration was lower than 1 mM, and were hydrolyzed and oxidized to MMA(V) and DMA(V), respectively. Metabolism of iAsIII to methylated arsenicals by Cyt19 was via ATG and MADG rather than by oxidative methylation of iAsIII and MMA(III).",
Arsenic,627159,"Urinary arsenic methylation and porphyrin profile of C57Bl/6J mice chronically exposed to sodium arsenate Abstract: Arsenic interferes with the function of enzymes responsible for haem biosynthesis leading to alteration in the porphyrin profile. In this study, young female C57Bl/6J mice were given drinking water containing 0, 100, 250 and 500 microg As(V)/L as sodium arsenate ad libitum for 24 months. 24 h pooled urine samples were collected bimonthly for urinary arsenic methylation and porphyrin analyses by HPLC-ICP-MS and HPLC respectively. The levels of total arsenic were significantly dose related except for the 2nd month interval. No significant differences in the urinary arsenic methylation pattern between control and test groups were observed. Coproporphyrin I (Copro I) showed a significant dose-response relationship after 12, 14 and 20 months of exposure. Significant differences in the levels of coproporphyrin III (Copro III) were observed in the 8th month in 250 and 500 microg/L treatment groups and the dose-response pattern was maintained after 10 and 12 months. Our results suggest that urinary arsenic is a useful biomarker for internal dose, and that urinary coproporphyrin can be used as an early warning biomarker of effects before the onset of cancer.",
Arsenic,37093,"Sampling private wells at past homes to estimate arsenic exposure: A methodologic study in New England Abstract: We are conducting a collaborative, population-based case-control study in Maine. New Hampshire. and Vermont to investigate the reasons for the elevated bladder cancer mortality in northern New England. Arsenic in drinking water is one of the primary exposures under investigation. To estimate subjects' lifetime exposure to waterborne arsenic, it will be necessary to obtain water samples from private wells that subjects used in the past. We conducted a methodologic study to assess the feasibility of locating and sampling from private wells at subjects' past residences. Ninety-eight New Hampshire residents (mean age 67 years) completed a questionnaire requesting the complete address, dates of occupancy, and drinking water sources for each home lived in since birth. An interviewer then asked subjects for more detailed information about each home to assist in a field search of past homes in the three-state study area of Maine, New Hampshire, and Vermont. Fifty-eight of the 98 subjects indicated that they had used a total of 103 private wells in 95 previous homes located in these three states. We conducted a field search to locate these 95 homes, visited town offices to find the properties on tax maps and obtain the current owners' names and addresses, attempted to obtain permission from the current owners to sample the wells, and collected water samples. In all, 48 (47%) of the 103 past wells in the study area were sampled successfully. The remaining wells were not sampled because the homes were not located (22%) or had been demolished (2%), permission to sample the wells was not obtained (17%), the wells had been destroyed (7%) or could not be found on the grounds of the residence (3%), or for other reasons (2%). Various approaches for improving the success rates for sampling Water from private wells are discussed, as is the use of predictive modeling to impute exposures when sampling is not feasible.",
Arsenic,1378573,"Perturbation Of Testicular Cell Proliferation Using Sodium Arsenite Abstract: In this study we report the effects of sodium arsenite exposure on the cell proliferation of the normalized mouse Leydig cell line, TM3. The Leydig cells were grown in culture medium containing 5% horse serum, 2.5% fetal bovine serum. Cell cultures were switched to serum-free medium prior to treatment with test compound. The treatments consisted of 1pg, 10pg, 100pg, 1ng, 10ng, and 100ng per ml sodium arsenite, along with a control. Results indicated a significant (p<=0.05) increase in cell proliferation in all treatments with growth ranging from 119.79 to 191.80%, with the exception of 100ng/ml when compared to the control. Peak proliferation for sodium arsenite was noted at 10pg/ml (191.80%). The other growth was recorded as follows: 166.88% at 1pg/ml, 163.03% at 100pg/ml, 155.32% at 1ng/ml, 126.80% at 10ng/ml, and 119.79% at 100ng/ml. These results are of concern given that sodium arsenite has previously been reportrd to decrease DNA repair. Hence, when coupled with our findings here, a mechanism for the induction of genomic instability can be postulated. This then may explain the carcinogenic activity of sodium arsenite.",
Arsenic,1028572,"Verapamil but not calpain or creatine alters arsenate-induced cardiac cell death Abstract: The objective of this study was to examine the potential of arsenate to induce cardiomyocyte cell death and to explore the cellular mechanisms of arsenate toxicity. Isolated cardiomyocytes in culture from embryonic chick hearts were treated with a pentavalent arsenic species (H3AsO4) or arsenate. Arsenate produced a significant (P &lt; 0.01) concentration-dependent increase in cell death with an EC50 about 1 mM. Cardiomyocytes manifested a loss of actin structure, reduced size, and damaged nuclei. Creatine 0.1-100 uM did not significantly modify arsenate-induced cell death. In contrast, verapamil, 0.01-1 uM, produced a significant concentration-dependent accentuation of arsenate-induced cell death. The effect of verapamil was evident at low concentrations of arsenate, which produced only a small increase in cell death, and at high concentrations of arsenate, which induced a large amount of cell death. Verapamil alone did not alter cardiomyocyte cell death. By comparison, calpain inhibitor II did not modify arsenate-induced cardiomyocyte cell death. These data suggest that cardiomyocytes are vulnerable to the effects of verapamil to increase the cellular toxicity of arsenate. Two potential cellular mechanisms of arsenate toxicity, however, are likely not involved in arsenate toxicity namely calpain activation and reduction of creatine phosphate production.",
Arsenic,627263,"Enhancement of platelet aggregation and thrombus formation by arsenic in drinking water: A contributing factor to cardiovascular disease Abstract: Arsenic in drinking water is a worldwide health problem that is associated with cardiovascular disease, but the cause is currently unknown. Arsenic effects on platelets, which are important in development of cardiovascular disease, were examined in vitro and in a drinking water study using a rat animal model. Trivalent inorganic arsenic (arsenite) induced in vitro aggregation when platelets were exposed to subthreshold challenge by thrombin and several other agonists in a concentration-dependent manner, with arsenite being the most potent form tested. Arsenite also induced significant increases in serotonin secretion, thromboxane A(2) formation, and adhesion protein expression in platelets. Consistent with the in vitro studies, 4-week ingestion of arsenite-contaminated drinking water resulted in enhanced arterial thrombosis. Human platelets showed similar responses, suggesting that the effects seen in animal experiments are applicable to humans. These results will provide new insights into the mechanism of arsenic-induced cardiovascular disease. They will also allow regulatory agencies to estimate risk from arsenic-induced cardiovascular disease and to determine if drinking water regulatory levels based on human cancer studies will protect against noncancer effects associated with cardiovascular disease.",
Arsenic,734903,"Genome-wide analysis of BEAS-2B cells exposed to trivalent arsenicals and dimethylthioarsinic acid Abstract: Lung is a major target for arsenic carcinogenesis in humans by both oral and inhalation routes. However, the carcinogenic mode of action of arsenicals is unknown. We investigated the effects of inorganic arsenic (iAsIII), monomethylarsonous acid (MMAIII), dimethylarsinous acid (DMAIII) and dimethylthioarsinic acid (DMTA), a sulfur containing dimethyl arsenic metabolite, in human bronchial epithelial (BEAS-2B) cells. Cells were exposed to 3, 15 microM-iAsIII; 0.3, 1 microM-MMAIII; 0.2, 1 microM-DMAIII; 0.2, 0.9 microM-DMTA as non-cytotoxic and minimally cytotoxic ( approximately 20%) concentrations based on Neutral Red uptake assays after 24h of culture. Total RNA was isolated and gene expression analysis conducted using Affymetrix Human Genome 133 Plus 2.0 arrays. Differentially expressed genes (DEGs) were determined using a one-way ANOVA (p &lt; or =0.05) by Rosetta Resolver, a Benjamini-Hochberg FDR (false discovery rate) multiple testing correction (&lt; 0.05) followed by a Scheffe's post hoc test. For all compounds except DMTA, &gt; 90% of DEG altered in the low concentration were also changed at the high concentration. There was a clear dose-response seen in the number of DEGs for all four compounds. iAsIII showed the highest number of DEG at both concentrations (2708 and 123, high and low, respectively). 1749, 420 and 120 DEGs were unique to the high concentrations of iAsIII, MMAIII and DMAIII, respectively. Transferrin receptor is a common DEG in low concentration arsenical treated cells. Ingenuity Pathway Analysis revealed p53 signaling (E2F1 and 2, SERPIN), and cell cycle related genes (cyclin D1) were altered by the high concentrations of DMTA, MMAIII and iAsIII. Oxidative stress (DUSP1, GPX2, NQO1, GCLC) and NF-kappaB signaling (TLR4, NF-kappaB) pathways were changed by the high concentrations of MMAIII and iAsIII. The genes identified in this study can be a valuable tool to determine the mechanism of arsenic toxicity and cancer formation. A number of similarities were observed in the gene expression profiles of DMAIII and DMTA and also iAsIII and MMAIII. These findings reveal some biological effects of arsenicals that will aid in creating a better risk assessment model for arsenical-induced lung cancer.",
Arsenic,1020531,"Enzymatic methylation of arsenic compounds. IX. Liver arsenite methyltransferase and arsenate reductase activities in primates Abstract: Inorganic arsenic is an important environmental toxicant of both natural and anthropogenic sources. It is a human carcinogen for which appropriate animal models of most arsenic-induced cancers are missing. Although methylation of inorganic arsenic has been considered its primary mechanism for detoxification, the results of recent investigations disagree. We have investigated 17 species of non-human primates, including great apes, New and Old World monkeys and prosimians, and have found that thirteen of them lacked hepatic arsenite methyltransferase activity in vitro. Four primate species, three from the Old World genus Macaca, and one of three animals from the New World genus Saimiri, had arsenite methyltransferase activity. That all the tissues examined were viable was demonstrated by their all having arsenate reductase activity. These data suggest that methylation of inorganic arsenic is not a detoxification mechanism for many non-human primates. Thus, alternative methods of detoxifying inorganic arsenic in mammals need to be considered and investigated. In addition, there appears to be a phylogenetic component to having arsenite methyltransferase activity, as evidenced by the result of our study of the Macaca species.",
Arsenic,1026653,"MicroRNA responses to cellular stress Abstract: Recent work has begun to explore the instrumental role that small noncoding RNA species, particularly microRNAs (miRNA), have both in classifying human tumors and in directing embryonic development. These studies suggest that developmental programs in essentially all organisms studied are set, in part, by varied expressions of miRNAs and that neoplasia is characterized by altered expression of miRNAs. Reasoning that these observations are linked, we examined whether cellular exposures that induce both developmental anomalies and cancer alter miRNAs. Using microarrays of 385 known human miRNAs, we studied human lymphoblastoid cells grown under various conditions or treatments. Folate deficiency induced a pronounced global increase in miRNA expression. We observed no significant alteration in miRNA expression in cells treated with gamma-irradiation, whereas exposure to sodium arsenite led to global increases in miRNA expression. The miRNA hsa-miR-222 was identified from these arrays as significantly overexpressed under folate-deficient conditions, and this finding was confirmed in vivo in human peripheral blood from individuals with low folate intake. Alterations to cellular miRNA expression profiles represent a novel mode of action of folate deprivation and arsenic exposure, and specific alterations in miRNA expression may be a powerful biomarker for these and other toxins with serious effects on human health.",
Arsenic,1508621,"Allosteric inhibition of a zinc-sensing transcriptional repressor: Insights into the arsenic repressor (ArsR) family Abstract: The molecular basis of allosteric regulation remains a subject of intense interest. Staphylococcus aureus CzrA is a member of the ubiquitous arsenic repressor (ArsR) family of bacterial homodimeric metal-sensing proteins and has emerged as a model system for understanding allosteric regulation of operator DNA binding by transition metal ions. Using unnatural amino acid substitution and a standard linkage analysis, we show that a His97' NH(?2)•••O=C His67 quaternary structural hydrogen bond is an energetically significant contributor to the magnitude of the allosteric coupling free energy, ?G(c). A &quot;cavity&quot; introduced just beneath this hydrogen bond in V66A/L68V CzrA results in a significant reduction in regulation by Zn(II) despite adopting a wild-type global structure and Zn(II) binding and DNA binding affinities only minimally affected from wild type. The energetics of Zn(II) binding and heterotropic coupling free energies (?H(c), -T?S(c)) of the double mutant are also radically altered and suggest that increased internal dynamics leads to poorer allosteric negative regulation in V66A/L68V CzrA. A statistical coupling analysis of 3000 ArsR proteins reveals a sector that links the DNA-binding determinants and the ?5 Zn(II)-sensing sites through V66/L68 in CzrA. We propose that distinct regulatory sites uniquely characteristic of individual ArsR proteins result from evolution of distinct connectivities to this sector, each capable of driving the same biological outcome, transcriptional derepression.",
Arsenic,2345837,"Contamination of floodplain soils along the Wupper River, Germany, with As, Co, Cu, Ni, Sb, and Zn and the impact of pre-definite redox variations on the mobility of these elements Abstract: This study demonstrates that floodplain soils of the River Wupper, Germany, are seriously contaminated with metal(loid)s. We used an automated biogeochemical microcosm system allowing controlled variation of redox potential (E-H) to assess the impact of pre-definite redox conditions on the dynamics of arsenic (As), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), antimony (Sb), and zinc (Zn) in homogenized soil material taken from an acid floodplain soil. The concentrations of Co, Cu, Mn, Ni, Sb, and Zn in soil solution were low at low E-H, possibly due to the precipitation of metal sulfides, and increased with rising E-H, presumably caused by their association with dissolved organic carbon (DOC). A significant positive correlation between metal/DOC-ratio and E-H indicated that the binding of the metals to DOC shifted from stronger to weaker when E-H rose. Decreasing As concentrations with increasing E-H in soil solution indicated co-precipitation with Fe(hydr)oxides and/or oxidation of more soluble As(III) to less soluble As(V) during oxidation. The other studied elements seemed not to co-precipitate with newly formed Fe(hydr)oxides when E-H rose, possibly due to the prevailing low pH. In the future, the specific role of DOC and sulfur chemistry on metal(loid) dynamics should be elucidated more fully, and similar studies should be conducted with additional frequently flooded soils worldwide to verify these results.",
Arsenic,627650,"The impact of diet and betel nut use on skin lesions associated with drinking-water arsenic in Pabna, Bangladesh Abstract: An established exposure-response relationship exists between water arsenic levels and skin lesions. Results of previous studies with limited historical exposure data, and laboratory animal studies suggest that diet may modify arsenic metabolism and toxicity. In this study, we evaluated the effect of diet on the risk of arsenic-related skin lesions in Pabna, Bangladesh. Six hundred cases and 600 controls loosely matched on age and sex were enrolled at Dhaka Community Hospital, Bangladesh, in 2001-2002. Diet, demographic data, and water samples were collected. Water samples were analyzed for arsenic using inductively coupled plasma mass spectroscopy. Betel nut use was associated with a greater risk of skin lesions in a multivariate model [odds ratio (OR) = 1.67; 95% confidence interval (CI), 1.18-2.36]. Modest decreases in risk of skin lesions were associated with fruit intake 1-3 times/month (OR = 0.68; 95%CI, 0.51-0.89) and canned goods at least 1 time/month (OR = 0.41; 95% CI, 0.20-0.86). Bean intake at least 1 time/day (OR = 1.89; 95% CI, 1.11-3.22) was associated with increased odds of skin lesions. Betel nut use appears to be associated with increased risk of developing skin lesions in Bangladesh. Increased intake of fruit and canned goods may be associated with reduced risk of lesions. Increased intake of beans may be associated with an increased risk of skin lesions. The results of this study do not provide clear support for a protective effect of vegetable and overall protein consumption against the development of skin lesions, but a modest benefit cannot be excluded.",
Arsenic,2064192,"Retardation of arsenic transport through a Pleistocene aquifer Abstract: Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of south and southeast Asia exposes an estimated population of over a hundred million people to toxic levels of arsenic. Holocene aquifers are the source of widespread arsenic poisoning across the region. In contrast, Pleistocene sands deposited in this region more than 12,000 years ago mostly do not host groundwater with high levels of arsenic. Pleistocene aquifers are increasingly used as a safe source of drinking water and it is therefore important to understand under what conditions low levels of arsenic can be maintained. Here we reconstruct the initial phase of contamination of a Pleistocene aquifer near Hanoi, Vietnam. We demonstrate that changes in groundwater flow conditions and the redox state of the aquifer sands induced by groundwater pumping caused the lateral intrusion of arsenic contamination more than 120 metres from a Holocene aquifer into a previously uncontaminated Pleistocene aquifer. We also find that arsenic adsorbs onto the aquifer sands and that there is a 16-20-fold retardation in the extent of the contamination relative to the reconstructed lateral movement of groundwater over the same period. Our findings suggest that arsenic contamination of Pleistocene aquifers in south and southeast Asia as a consequence of increasing levels of groundwater pumping may have been delayed by the retardation of arsenic transport.",
Arsenic,1381623,"Increasing neutrophil F-actin corrects CD11b exposure in Type 2 diabetes Abstract: <strong>BACKGROUND: </strong>Leukocyte dysfunction contributes to the pathogenesis of diabetic vascular complications. Neutrophils adhere to the endothelium through the beta(2)integrin CD11b/CD18. In Type 2 diabetes, neutrophil surface CD11b expression is increased and is associated with impaired actin polymerization. This study aimed to determine whether increasing neutrophil actin polymerization could correct the defect in CD11b exposure.<br /><br /><strong>DESIGN: </strong>Neutrophil actin polymerization was stimulated with the tyrosine phosphatase inhibitor phenylarsine oxide (PAO), and cytoskeletal phosphotyrosine was monitored by immunoblotting Triton X-100 insoluble fractions of cells. Neutrophil F-actin was measured with phalloidin-FITC staining, and surface CD11b expression was determined with anti-CD11b-PE before analysis with flow cytometry.<br /><br /><strong>RESULTS: </strong>Phenylarsine oxide caused an increase in phosphotyrosine in neutrophils from both patients with Type 2 diabetes (DM) and controls (NC) (-fold increase: NC, 1.43 +/- 0.16; DM, 1.46 +/- 0.10). The response to PAO in terms of phalloidin-binding was impaired in neutrophils from patients [phalloidin-FITC MFI area under the curve, NC 200 +/- 5 (x 10(3)), DM 124 +/- 9 (x 10(3)), P &lt; 0.0001]. Phenylarsine oxide at concentrations &lt; 10 micro mol L(-1) also caused loss of CD11b from neutrophil surfaces that was impaired in samples from patients [CD11b sites area under the curve NC 90 +/- 6 (x 10(3)), DM 121 +/- 9 (x 10(3)), P &lt; 0.002]. However, in neutrophils from patients, incubation with PAO at a concentration of &gt; 10 micro mol L(-1) caused a significant increase in intracellular F-actin and CD11b down-regulation equivalent to that observed in controls.<br /><br /><strong>CONCLUSION: </strong>In Type 2 diabetes, impaired neutrophil actin polymerization even in response to increasing cytoskeletal phophotyrosine suggests a downstream defect. Furthermore, increasing actin polymerization, above a minimum threshold level, corrects the defect in integrin exposure. Correction of the actin polymerization defect in Type 2 diabetes could improve the prognosis of diabetic vascular complications.",
Arsenic,627311,"Variability in sensitivity to arsenite does not correlate with arsenic accumulation rate in normal human lymphoblasts Abstract: Arsenic is a common environmental contaminant of our air, water and food, but not every individual who drinks arsenic-contaminated water shows clinical signs of toxicity. Large inter-individual variations are also found in arsenite-induced aneuploidy, chromosome aberrations and sister chromatid exchanges in peripheral blood lymphocytes from different human donors. Lymphoblasts are virally immortalized lymphocytes that retain most of the properties of lymphocytes. Individual lymphoblast cell lines retained their arsenite sensitivity after cryopreservation and subsequent revival. We measured the accumulation of 73[As]-arsenite into lymphoblast lines derived from 11 normal individuals. Arsenite accumulation rate varied 6.3 fold between the slowest and the fastest subjects. Assays in 14 lymphoblast lines showed variability to the toxic effects of arsenite, as measured by growth inhibition. Lymphoblast lines also vary with regard to their growth rates, but there is no relationship between growth rate and arsenite sensitivity. Surprisingly, we also found no correlation between arsenite accumulation rate and cellular sensitivity to growth inhibition, suggesting that the arsenite accumulation rate may not be the main determinant of cellular sensitivity to arsenic. We were also unable to detect evidence for a human homolog for the yeast arsenite efflux gene ACR3, using RT-PCR.",
Arsenic,627004,"Interaction of trivalent arsenicals with metallothionein Abstract: Arsenic is a human carcinogen, causing skin, bladder, and lung cancers. Although arsenic in drinking water affects millions of people worldwide, the mechanism(s) of action by which arsenic causes cancers is not known. Arsenic probably exerts some toxic effects by binding with proteins. However, few experimental data are available on arsenic-containing proteins in biological systems. This study reports on arsenic interaction with metallothionein and established binding stoichiometries between metallothionein and the recently discovered trivalent metabolites of arsenic metabolism. Size exclusion chromatography with inductively coupled plasma mass spectrometry analysis of reaction mixtures between trivalent arsenicals and metallothionein clearly demonstrated the formation of complexes of arsenic with metallothionein. Analysis of the complexes using electrospray quadrupole time-of-flight tandem mass spectrometry revealed the detailed binding stoichiometry between arsenic and the 20 Cys residues in the metallothionein molecule. Inorganic arsenite (As(III)) and its two trivalent methylation metabolites, monomethylarsonous acid (MMA(III)) and dimethylarsinous acid (DMA(III)), readily bind with metallothionein. Each metallothionein molecule could bind with up to six As(III), 10 MMA(III), and 20 DMA(III) molecules, consistent with the coordination chemistry of these arsenicals. The findings on arsenic interaction with proteins are useful for a better understanding of arsenic health effects.",
Arsenic,1337749,"Total and inorganic arsenic in freshwater fish and prawn in Thailand Abstract: Total and inorganic arsenic levels were determined in 120 samples of eight freshwater animal species collected from five distribution centers in the central region of Thailand between January and March 2011. Eight species with the highest annual catch, consisting of seven fish species and one prawn species, were analyzed. Concentrations of inorganic arsenic (on a wet weight basis) ranged from 0.010 ?g/g in giant prawn (Macrobrachium rosenbergii) to 0.230 ?g/g in striped snakehead (Channa striata). Climbing perch (Anabas testudineus) exhibited the highest mean concentrations of total arsenic (0.459 ± 0.137 ?g/g), inorganic arsenic (0.121 ± 0.044 ?g/g), and percentage of inorganic arsenic (26.2%). Inorganic arsenic levels found in freshwater animals in this study were much lower than the Thai regulatory standard of 2 ?g/g.",
Arsenic,1022914,"Delivery of midinfrared (6 to 7-microm) laser radiation in a liquid environment using infrared-transmitting optical fibers Abstract: Ablation at wavelengths near lambda = 6.45 microm results in tissue ablation with minimal collateral damage (&lt; 40 microm) yet yields a high ablation rate that is useful for human surgery. However, delivery of this wavelength has been limited to that in air and thus to applications in which the target tissue can be readily exposed. The goal of this study is to investigate the potential of a pulsed infrared laser at lambda = 6.45 microm for noncontact ablation in a liquid environment. To this end we investigated fiber delivery in combination with the use of infrared transparent liquids. Transmission characteristics and damage thresholds for two types of fiber materials (silver halide and arsenic sulfide), for high-power pulsed laser radiation were determined using the Mark III free electron laser. Both fibers had comparable bulk losses (0.54 dB/m and 0.62 dB/m, respectively) while the arsenic sulfide fibers showed more coupling losses (37 versus 27%). Damage thresholds were higher in arsenic sulfide fibers than in silver halide fibers (1.12 GW/cm2 versus 0.54 GW/cm2), but both fibers were sufficient to deliver radiant exposures well above the ablation threshold in tissue. Seven different perfluorocarbon liquids (PFCLs), known for their transparency at lambda = 2.94 microm, were investigated and their optical transmission was determined using Fourier transform infrared and direct Beer's law measurements. All of the PFCLs tested had similar values for an absorption coefficient mu(a) at a given wavelength (mu(a) = 0.05 mm(-1) at lambda = 2.94 microm and mu(a) is approximately 3 mm(-1) at lambda = 6.45 microm). Pump-probe imaging showed the ablation sequence (lambda = 6.45 microm) at the fiber tip in a water environment, which revealed a fast expanding and collapsing bubble. In contrast, the volatile PF-5060 showed no fast bubble expansion and collapse, but rather formation of nontransient gas bubbles. Perfluorodecalin did not show any bubble formation at the radiant exposures used. It was shown that using the lambda = 6.45 microm wavelength delivered via fiber optics in combination with perfluorodecalin allows a noncontact laser surgical procedure. Deeper structures, however, are effectively shielded because the radiant exposure of the beam will fall below the ablation threshold owing to the absorption by perfluorodecalin. This may optimize the efficacy and safety of laser-based vitreoretinal surgery.",
Arsenic,2279517,"Effects of antimony and arsenic on antioxidant enzyme activities of two steppic plant species in an old antimony mining area Abstract: The present work was undertaken to determine strategies and antioxidant enzyme activities involved in the adaptation of two wild steppic plants (Hedysarum pallidum Desf. and Lygeum spartum L.) to the toxic environment of the abandoned antimony mining area of Djebel Hamimat (Algeria). For this purpose, soils and plants were collected in different zones coinciding with a Sb and As concentrations gradient in the soil. Antimony (Sb) and arsenic (As) were analyzed by ICP-OES in the soils and the aboveground parts and roots of the plants. Malondialdehyde (MDA) and antioxidant enzyme activities were measured by spectrometry. Results show levels of Sb and As exceptionally high in most soil and plant samples. The two species accumulate differently Sb and As in their above and belowground parts. MDA levels, in the two parts of both species, increase significantly with increasing soil Sb and As concentrations, but they are significantly higher in H. pallidum than in L. spartum. The activities of antioxidant enzymes differ significantly according to the soil metalloid concentrations, the plant species considered and the plant part. Apart from superoxide dismutase (SOD) whose activity is, overall, higher in H. pallidum than in L. spartum, the activities of all the other enzymes studied (glutathione S-transferase (GST), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX)) are generally higher in L. spartum than in H. pallidum. For both species, APX and GST are overall more active in the upper parts than in the roots, while it is the reverse for SOD and CAT. POD is more active in the upper parts than in the roots of L. spartum and the reverse applies to H. pallidum. It appears that the two studied plant species use different tolerance strategies to protect themselves against elevated As and Sb concentrations.",
Arsenic,1018643,"Fate and effects of soluble or sediment-bound arsenic in oysters (Crassostrea gigas Thun.) Abstract: Contaminated sediments are a possible source of stress to the benthic biota. In order to examine this way of transfer concurrently with direct exposure, oysters were exposed to As dissolved in natural seawater or loaded to particles. The sediment used as a vector of transfer was a mud from a coastal area devoted to oyster culture, the finest particles of which have been selected. It was submitted to experimental contamination then to in vitro desorption tests, in which enzymes and pH changes were used to mimic the digestive processes in Molluscs. Although different enzymes or pH induced the desorption of 3 to 24% of sediment-bound arsenic, the accumulation of this element in the soft tissues of oysters remained low after exposure to contaminated particles. The uptake of soluble arsenic was also limited although checking the level of arsenic in seawater every day revealed no significant decrease of the contaminant in the experimental medium. However, cytological effects were noted in oysters exposed to sediment-bound arsenic and moreover to soluble arsenic. They consisted of structural alterations of mitochondria and nuclei, suggesting a disturbance of both the cellular respiratory metabolism and nucleotid incorporation.",
Arsenic,1017709,"Protective effect of Corchorus olitorius leaves on sodium arsenite-induced toxicity in experimental rats Abstract: The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves (AECO) against sodium arsenite-induced toxicity in experimental rats. The animals exposed to sodium arsenite at a dose of 10mg/kg body weight p.o. for 10days exhibited a significant inhibition (p&lt;0.01) of hepatic and renal antioxidant enzymes namely superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase and glutathione reductase. In addition, arsenic intoxication significantly decreased (p&lt;0.01) the level of reduced glutathione and increased (p&lt;0.01) the levels of oxidized glutathione and thiobarbituric acid reactive substances in selected tissues. Treatment with AECO at doses of 50 and 100mg/kg body weight p.o. for 15days prior to arsenic intoxication significantly improved hepatic and renal antioxidant markers in a dose dependant manner. AECO treatment also significantly reduced the arsenic-induced DNA fragmentation of hepatic and renal tissues. Histological studies on the ultrastructural changes of liver and kidney supported the protective activity of the AECO. The results concluded that the treatment with AECO prior to arsenic intoxication has significant role in protecting animals from arsenic-induced hepatic and renal toxicity.",
Arsenic,710888,"Chronic exposure to low levels of inorganic arsenic causes alterations in locomotor activity and in the expression of dopaminergic and antioxidant systems in the albino rat Abstract: Several studies have associated chronic arsenicism with decreases in IQ and sensory and motor alterations in humans. Likewise, studies of rodents exposed to inorganic arsenic ((i)As) have found changes in locomotor activity, brain neurochemistry, behavioral tasks, oxidative stress, and in sensory and motor nerves. In the current study, male Sprague-Dawley rats were exposed to environmentally relevant doses of (i)As (0.05, 0.5 mg (i)As/L) and to a high dose (50 mg (i)As/L) in drinking water for one year. Hypoactivity and increases in the striatal dopamine content were found in the group treated with 50 mg (i)As/L. Exposure to 0.5 and 50 mg (i)As/L increased the total brain content of As. Furthermore, (i)As exposure produced a dose-dependent up-regulation of mRNA for Mn-SOD and Trx-1 and a down-regulation of DAR-D? mRNA levels in the nucleus accumbens. DAR-D? and Nrf2 mRNA expression were down-regulated in nucleus accumbens in the group exposed to 50 mg (i)As/L. Trx-1 mRNA levels were up-regulated in the cortex in an (i)As dose-dependent manner, while DAR-D? mRNA expression was increased in striatum in the 0.5 mg (i)As/L group. These results show that chronic exposure to low levels of arsenic causes subtle but region-specific changes in the nervous system, especially in antioxidant systems and dopaminergic elements. These changes became behaviorally evident only in the group exposed to 50 mg (i)As/L.",1
Arsenic,1614967,"Association of arsenic with nutrient elements in rice plants Abstract: Rice is the main cereal crop that feeds half of the world's population, and two thirds of the Chinese population. Arsenic (As) contamination in paddy soil and irrigation water elevates As concentration in rice grains, thus rice consumption is an important As intake route for populations in south and south-east Asia, where rice is the staple food. In addition to direct toxicity of As to human, As may limit the accumulation of micro-nutrients in rice grains, such as selenium (Se) and zinc (Zn). These micro-nutrients are essential for humans, while mineral deficiencies, especially iron (Fe) and Zn, are prevalent in China. Therefore, it is important to understand the interactions between As and micro-nutrients in rice plants, which is the principal source of these nutrients for people on rice diets. In addition, during the processes of As uptake, translocation and transformation, the status of macro-nutrients (e.g. silicon (Si), phosphors (P), sulfur (S)) are important factors affecting As dynamics in soil-plant systems and As accumulation in rice grains. Recently, synchrotron-based spectroscopic techniques have been applied to map the distribution of As and nutrient elements in rice plants, which will aid to understand how As are accumulated, complexed and transported within plants. This paper reviews the interactions between As and macro-nutrients, as well as micro-nutrients in rice plants.",
Arsenic,134647,"Tissue dosimetry, metabolism and excretion of pentavalent and trivalent monomethylated arsenic in mice after oral administration Abstract: Exposure to monomethylarsonic acid (MMA(V)) and monomethylarsonous acid (MMA(III)) can result from their formation as metabolites of inorganic arsenic and by the use of the sodium salts of MMA(V) as herbicides. This study compared the disposition of MMA(V) and MMA(III) in adult female B6C3F1 mice. Mice were gavaged po with MMA(V), either unlabeled or labeled with 14C at two dose levels (0.4 or 40 mg As/kg). Other mice were dosed po with unlabeled MMA(III) at one dose level (0.4 mg As/kg). Mice were housed in metabolism cages for collection of excreta and sacrificed serially over 24 h for collection of tissues. MMA(V)-derived radioactivity was rapidly absorbed, distributed and excreted. By 8 h post-exposure, 80% of both doses of MMA(V) were eliminated in urine and feces. Absorption of MMA(V) was dose dependent; that is, there was less than a 100-fold difference between the two dose levels in the area under the curves for the concentration-time profiles of arsenic in blood and major organs. In addition, urinary excretion of MMA(V)-derived radioactivity in the low dose group was significantly greater (P < 0.05) than in the high dose group. Conversely, fecal excretion of MMA(V)-derived radioactivity was significantly greater (P < 0.05) in the high dose group than in the low dose group. Speciation of arsenic by hydride generation-atomic absorption spectrometry in urine and tissues of mice administered MMA(V) or MMA(III) found that methylation of MMA(V) was limited while the methylation of MMA(III) was extensive. Less than 10% of the dose excreted in urine of MMA(V)-treated mice was in the form of methylated products, whereas it was greater than 90% for MMA(III)-treated mice. In MMA(V)-treated mice, 25% or less of the tissue arsenic was in the form of dimethylarsenic, whereas in MMA(III)-treated mice, 75% or more of the tissue arsenic was in the form of dimethylarsenic. Based on urinary analysis, administered dose of MMA(V) did not affect the level of its metabolites excreted. In the tested range, dose affects the absorption, distribution and route of excretion of MMA(V) but not its metabolism.",
Arsenic,2064143,Trace element uptake dynamics for maize (Zea mays L.) grown under field conditions Abstract: ,
Arsenic,1936055,"Reduced in vitro toxicity of fine particulate matter collected during the 2008 summer Olympic Games in Beijing: The roles of chemical and biological components Abstract: Beijing has implemented systematic air pollution control legislation to reduce particulate emissions and improve air quality during the 2008 Summer Olympics, but whether the toxicity of fine fraction of particles (PM2.5) would be changed remains unclear. In present study we compared in vitro biological responses of PM2.5 collected before and during the Olympics and tried to reveal possible correlations between its chemical components and toxicological mechanism(s). We measured cytotoxicity, cytokines/chemokines, and related gene expressions in murine alveolar macrophages, MH-S, after treated with 20PM2.5 samples. Significant, dose-dependent effects on cell viability, cytokine/chemokine release and mRNA expressions were observed. The cytotoxicity caused at equal mass concentration of PM2.5 was notably reduced (p<0.05) by control measures, and significant association was found for viability and elemental zinc in PM2.5. Endotoxin content in PM2.5 correlated with all of the eight detected cytokines/chemokines; elemental and organic carbon correlated with four; chromium and arsenic correlated with six and three, respectively; iron and barium showed associations with two; nickel, magnesium, potassium, and calcium showed associations with one. PM2.5 toxicity in Beijing was substantially dependent on its chemical components, and lowering the levels of specific components in PM2.5 during the 2008 Olympics resulted in reduced biological responses.",
Arsenic,656771,"A preliminary investigation of the effects of arsenate on irradiation-induced DNA damage in cultured human lung fibroblasts Abstract: Single-cell gel electrophoresis (the comet assay) was used to assess single-strand breaks (SSBs) produced in cultured lung human fibroblasts by xenon lamp irradiation alone, various concentrations of arsenate [As(V)], alone or various combinations of the two. It was found that significantly higher levels of SSBs were observed in the irradiated cells than the nonirradiated cells and that elevating levels of arsenate enhanced the level of damage detected in both irradiated and nonirradiated cells in a concentration-dependent manner; that is, incubating cells with arsenate alone produced marked DNA damage without an irradiation insult being necessary. The results of this study indicate that arsenate is acting as a cogenotoxin with irradiation in this cell line. This additive effect may also be cocarcinogenic, and as a result it is possible that less solar irradiation may be required to induce skin cancer in arsenic-exposed populations.",
Arsenic,2279349,"Effect of prenatal arsenic exposure on DNA methylation and leukocyte subpopulations in cord blood Abstract: Prenatal arsenic exposure is associated with increased risk of disease in adulthood. This has led to considerable interest in arsenic's ability to disrupt fetal programming. Many studies report that arsenic exposure alters DNA methylation in whole blood but these studies did not adjust for cell mixture. In this study, we examined the relationship between arsenic in maternal drinking water collected ? 16 weeks gestational age and DNA methylation in cord blood (n = 44) adjusting for leukocyte-tagged differentially methylated regions. DNA methylation was quantified using the Infinium HumanMethylation 450 BeadChip array. Recursively partitioned mixture modeling examined the relationship between arsenic and methylation at 473,844 CpG sites. Median arsenic concentration in water was 12 µg/L (range<1- 510 µg/L). Log 10 arsenic was associated with altered DNA methylation across the epigenome (P = 0.002); however, adjusting for leukocyte distributions attenuated this association (P = 0.013). We also observed that arsenic had a strong effect on the distribution of leukocytes in cord blood. In adjusted models, every log 10 increase in maternal drinking water arsenic exposure was estimated to increase CD8+ T cells by 7.4% (P = 0.0004) and decrease in CD4+ T cells by 9.2% (P = 0.0002). These results show that prenatal exposure to arsenic had an exposure-dependent effect on specific T cell subpopulations in cord blood and altered DNA methylation in cord blood. Future research is needed to determine if these small changes in DNA methylation alter gene expression or are associated with adverse health effects.",
Arsenic,1343455,"Phenotypic and genotypic characterizations of rhizobia isolated from root nodules of multiple legume species native of Fez, Morocco Abstract: ",
Arsenic,1070422,"Quantitative imaging of arsenic and its species in goat following long term oral exposure Abstract: Severity of arsenic toxicity was reported to vary depending on its species. The present study reflects the status of different species of arsenic in goat following long-term exposure of arsenic leading to hepatic damage. The experiment was conducted with six black Bengal goats, which were administered with sodium arsenite orally at a dose rate of 2mgkg(-1) daily for 84days. Faeces, urine, hair and blood samples were collected from those animals at 14days interval. Excretion of total arsenic was reduced from 56days onwards through both faeces and urine indicating higher accumulation of arsenic in body. The speciation study revealed that urinary arsenic was mainly of organic type, whereas hair accumulated almost equal proportion of arsenite, arsenate and organo arsenicals. Goats excreted high proportion of organo arsenicals through faeces possibly due to hepatobiliary secretion of organo arsenic into the gut. Significantly elevated serum alanine aminotransferase and aspartate aminotransferase activities (p<0.05) alongwith histopathological changes in liver indicated hepatotoxicity. The arsenite fraction increased and organic proportion decreased in urine as the time progressed, which indicates that arsenite gets methylated in liver of goat. The study thus alluded that the toxicity of arsenic would aggravate if the animals were exposed for long time as the hepatotoxicity progressed resulting in decreased methylation and formation of organo arsenicals and decreased excretions through urine.",
Arsenic,1371600,"Significance Of Interactions Between Essential And Toxic Metal Ions In The Cellular Response To DNA Damage Abstract: Nickel, cadmium, cobalt and arsenic compounds are well known carcinogens to humans and experimental animals. In addition to the induction of mainly oxidative DNA damage, they interfere with nucleotide and base excision repair at low, noncytotoxic concentrations. As potential molecular targets, interactions with so-called zinc finger proteins involved in DNA repair and/or DNA damage signaling such as XPA and PARP have been identified. Thus, trivalent inorganic and biomethylated arsenicals have been shown to release zinc from the zinc finger domain of the human repair protein XPA (XPAzf ). Furthermore, NiCl2 and CdCl2 deform the zinc finger structure of XPA: XPAzf exerts a 1000-fold higher binding constant for cadmium than for zinc and NiCl2 increases XPAzf sensitivity towards oxidation. At the cellular level, arsenite and its trivalent methylated metabolites suppress poly(ADP-ribosyl)ation at very low, nanomolar concentrations. In support of this observation, the same trivalent compounds inhibited isolated PARP-1, while no effect on PARP-1 gene expression was detected. A zinc binding motif is also present in p53, and different Cd compounds convert the correctly folded ?wild type? conformation almost completely into a so-called ?mutant? form with an unfolded zinc binding domain. This is accompanied by alterations in p53-dependent gene expression and cell cycle control. Remarkably, an interaction with zinc finger structures may also occur by essential trace elements: Reducible selenium compounds deliberate zinc from XPA and provoke p53 conformational changes, presumably by oxidation of cysteines in zinc binding motifs. Thus, certain selenium compounds may exert anticarcinogenic effects at low levels but may compromise genetic stability at higher concentrations which could be reached by dietary supplements.",
Arsenic,1350554,"Speed-mapping of arsenic distribution in the tissues of earthworms inhabiting arsenious soil Abstract: We have examined the distribution of arsenic in the metal-sequestering chloragogenous tissue of a population of the earthworm, Lumbricus rubellus, exposed to the metalloid in its natural environment. The localization technique was qualitative digital X-ray speed mapping (2 minute total acquisition time) of fresh air dried tissue smears. Arsenic was located in association with sulphur in a discrete chloragocytic compartment; it was not detected in the phosphate-rich chloragosome granules. In earthworm tissues arsenic was distributed according to its sulphydryl-seeking trivalent form, not as the phosphate-resembling pentavalent form.",
Arsenic,78768,"Bladder cancer mortality associated with arsenic in drinking water in Argentina Abstract: Inorganic arsenic (In-As) is known to be a human carcinogen, causing lung cancer by inhalation and skin cancer by ingestion. Ecologic studies in Taiwan have found a dose-response relation between ingestion of In-As from drinking water and bladder cancer, but questions have been raised concerning the validity and generalizability of the findings. Several areas of Argentina have had high exposures to arsenic from naturally contaminated drinking water, particularly the eastern region of the province of Córdoba. In this study, we investigated bladder cancer mortality for the years 1986-1991 in Córdoba's 26 counties, using rates for all of Argentina as the standard for comparison. Bladder cancer standardized mortality ratios (SMRs) were consistently higher in counties with documented arsenic exposure. We grouped counties into low-, medium-, and high-exposure categories; the corresponding SMRs [with 95% confidence intervals (CI)] were 0.80 (95% CI = 0.66-0.96), 1.42 (95% CI = 1.14-1.74), and 2.14 (95% CI = 1.78-2.53) for men, and 1.21 (95% CI = 0.85-1.64), 1.58 (95% CI = 1.01-2.35), and 1.82 (95% CI = 1.19-2.64) for women. The clear trends found in a population with different genetic composition and a high-protein diet support the findings in Taiwan.",
Arsenic,137340,"In vitro methylation of inorganic arsenic in mouse intestinal cecum Abstract: The capacity of mouse intestinal cecal microflora to methylate inorganic arsenicals (iAs) was examined in vitro under conditions of restricted bacterial growth. Cecal contents incubated under anaerobic conditions at 37 degrees C for 21 hr methylated up to 40% of either 0.1 microM arsenite (iAsIII) or 0.1 microM arsenate (iAsV). Methylarsenic (MAs) was the predominant metabolite; however, about 3% of either substrate was converted to dimethylarsenic (DMAs). Over the first 6 hr, the rate of methylation was several times greater for iAsIII than for iAsV. There was a 3-hr delay in the production of methylated metabolites from iAsV, suggesting that reduction of iAsV to iAsIII before methylation could be rate limiting. Over the concentration range of 0.1 to 10 microM of iAsIII or iAsV, there was an approximately linear increase in the production of MAs and DMAs. There was evidence of saturation or inhibition of methylation at 100 microM of either substrate. Substrate concentration had little effect on MAs/DMAs ratio. Incubation of cecal contents at 0 degrees C abolished methylation of either arsenical. Under aerobic or anaerobic conditions, cecal tissue homogenates produced little MAs or DMAs from either arsenical. Addition of potential methyl group donors, L-methionine and methylcobalamin, into cecal contents significantly increased the rate of methylation, especially for iAsV. Addition of glutathione, but not L-cysteine, had a similar effect. Selenite, a recognized inhibitor of iAs methylation in mammalian tissues, inhibited methylation of either substrate by cecal contents. These data suggest that cecal microflora are a high capacity methylation system that might contribute significantly to methylation of iAs in intact animals.",
Arsenic,2337153,"The Combination Of Arsenic, Interferon-Alpha, and Zidovudine Restores An ""Immunocompetent-like"" Micro-Environment In Patients With Adult T- Cell Leukemia/Lymphoma Abstract: ",
Arsenic,1348065,Adsorption of chromate on variable charge soils as influenced by ionic strength Abstract: ,
Arsenic,1026409,"Trivalent arsenicals are bound to proteins during reductive methylation Abstract: Inorganic arsenic is converted to methylated metabolites, and most is excreted in urine as dimethylarsinic acid in humans and animals. The present study was conducted to investigate the metabolism of arsenic and identify hepatic and renal metabolites of arsenic after an intravenous injection of arsenite (0.5 mg As/kg body weight) in rats. Similar levels of arsenic were found in the soluble (SUP) and nonsoluble sediment (SED) fractions of both organs after 1 h. More than 80% of the SUP arsenic was bound to high molecular weight (HMW) proteins in both organs. Arsenic bound to the HMW and SED proteins were oxidized with H(2)O(2) and released in the pentavalent forms (arsenate, monomethylarsonic, and dimethylarsinic acids). The relative ratios of the three arsenicals changed depending on organ, fraction (HMW and SED), and time. Since the arsenic metabolites/intermediates were liberated from proteins by oxidation with H(2)O(2) and recovered in the pentavalent forms, and only tri- but not pentavalent arsenicals were bound to proteins in vitro, it was deduced that arsenic metabolites bound to proteins during the successive methylation pathway are in the trivalent forms; that is, successive methylation reaction takes place with simultaneous reductive rather than stepwise oxidative methylation. Thus, on the basis of the present observations, it was proposed that inorganic arsenic was successively methylated reductively in the presence of glutathione, rather than a stepwise oxidative methylation, and pentavalent arsenicals (MMA(V) and DMA(V)) were present as end products of metabolism, rather than intermediates. We also discussed the in vitro formation of dimethylthioarsenicals after incubating dimethylarsinous acid with liver homogenate.",
Arsenic,2149162,"Exposure to metals during pregnancy and neuropsychological development at the age of 4 years Abstract: <strong>BACKGROUND: </strong>There is insufficient epidemiological evidence for deciding whether prenatal exposure to the current low-levels of metals in developed countries may affect neuropsychological function in early childhood.<br /><br /><strong>OBJECTIVES: </strong>Our goal was to evaluate potential neurotoxic effects of prenatal exposure to seven metals (cobalt, copper, arsenic, cadmium, antimony, thallium and lead), during the 1st and 3rd trimester of pregnancy, on child neuropsychological development at 4 years of age.<br /><br /><strong>MATERIALS AND METHODS: </strong>This study was based on a population-based birth cohort established in Sabadell (Catalonia, Spain) as part of the INMA [Environment and Childhood] Project. Metals were measured in 485 urine samples collected from mothers during the 1st and 3rd trimester of pregnancy. We assessed the neuropsychological development of 553 4-year-olds with the McCarthy Scales of Childrens' Abilitites (MSCA), together with their ADHD symptomatology, using the ADHD-DSM-IV criteria. A total of 385 children were included in the present study.<br /><br /><strong>RESULTS: </strong>We found no statistically significant associations between metals and general cognitive scale or executive function of the MSCA. We found negative coefficients for the exposure to cadmium 1st trimester, cadmium 3rd trimester and lead 3rd trimester on the general cognitive score of MSCA, although these results were not significant. We did not find any association between prenatal exposure to metals and ADHD symptomatology at the age of 4 years.<br /><br /><strong>CONCLUSIONS: </strong>Our results do not suggest that prenatal exposure to current low-levels of metals impairs children's cognitive development during preschool years.",
Arsenic,1025334,"Exposure and health risk of gallium, indium, and arsenic from semiconductor manufacturing industry workers Abstract: ",
Arsenic,1936052,"Arsenic Resistance and Prevalence of Arsenic Resistance Genes in Campylobacter jejuni and Campylobacter coli Isolated from Retail Meats Abstract: Studies that investigate arsenic resistance in the foodborne bacterium Campylobacter are limited. A total of 552 Campylobacter isolates (281 Campylobacter jejuni and 271 Campylobacter coli) isolated from retail meat samples were subjected to arsenic resistance profiling using the following arsenic compounds: arsanilic acid (4-2,048 ?g/mL), roxarsone (4-2048 ?g/mL), arsenate (16-8,192 ?g/mL) and arsenite (4-2,048 ?g/mL). A total of 223 of these isolates (114 Campylobacter jejuni and 109 Campylobacter coli) were further analyzed for the presence of five arsenic resistance genes (arsP, arsR, arsC, acr3, and arsB) by PCR. Most of the 552 Campylobacter isolates were able to survive at higher concentrations of arsanilic acid (512-2,048 ?g/mL), roxarsone (512-2,048 ?g/mL), and arsenate (128-1,024 ?g/mL), but at lower concentrations for arsenite (4-16 ?g/mL). Ninety seven percent of the isolates tested by PCR showed the presence of arsP and arsR genes. While 95% of the Campylobacter coli isolates contained a larger arsenic resistance operon that has all of the four genes (arsP, arsR, arsC and acr3), 85% of the Campylobacter jejuni isolates carried the short operon (arsP, and arsR). The presence of arsC and acr3 did not significantly increase arsenic resistance with the exception of conferring resistance to higher concentrations of arsenate to some Campylobacter isolates. arsB was prevalent in 98% of the tested Campylobacter jejuni isolates, regardless of the presence or absence of arsC and acr3, but was completely absent in Campylobacter coli. To our knowledge, this is the first study to determine arsenic resistance and the prevalence of arsenic resistance genes in such a large number of Campylobacter isolates.",
Arsenic,657849,"Association of respiratory complications and elevated serum immunoglobulins with drinking water arsenic toxicity in human Abstract: We assessed the relationship between chronic arsenic exposure through drinking water with respiratory complications and humoral immune response by measuring serum immunoglobulin profiles in the affected subjects (arsenicosis patients) living in the arsenic endemic rural villages of Bangladesh. The duration of exposure was determined through detailed history of the patients (n=125) and the levels of arsenic in the drinking water and urine samples were determined. The mean duration of exposure in the patients was 7.4+/-5.3 y, and the levels of arsenic in the drinking water and urine samples were 216+/-211 and 223+/-302 micro g/L, respectively, compared to 11+/-20 and 29+/-19 microg/L, respectively, in the unexposed subjects. There was high prevalence of respiratory complications like breathing problems including chest sound, asthma, bronchitis and cough associated with drinking water arsenic toxicity. Arsenicosis patients had significantly elevated levels of IgG (P<0.001) and IgE (P<0.001) while the levels of IgA were also significantly higher (P<0.005) but IgM were similar to that of the control subjects. Analysis of the clinical symptoms based on skin manifestations showed the levels of both IgG and IgE were significantly elevated during the initial stages while IgE were further elevated with the duration of arsenic exposure. Arsenicosis patients with respiratory complications had mean serum IgE levels of 706+/-211 IU/mL compared to 542+/-241 IU/mL in patients without apparent involvement with the respiratory system (P<0.01). The eosinophil counts in the patients did not differ significantly from the unexposed subjects indicating that elevated levels of serum IgE might not be due to allergic diseases, rather it could be due to direct effects of arsenic. We found significant linear relationships between the levels of serum IgE and inorganic phosphorus (P<0.05), and serum IgA levels with urinary excretion of arsenic (P<0.001). These observations suggested that arsenic toxicity caused respiratory complications, induced changes in the humoral as well as mucosal immune responses.",
Arsenic,1519020,"Factors affecting chelating extraction of Cr, Cu, and As from CCA-treated wood Abstract: The disposal of chromated copper arsenate (CCA)-treated waste wood is becoming a serious problem in many countries due to potential leaching of hazardous elements from in-service use in the environment or disposal of solutions after remediation; therefore, it is necessary to develop proper remediation techniques. The effects of concentration, extraction period, temperature, and sequential extraction on the extraction of Cr, Cu, and As from CCA-treated wood using [S,S]-ethylenediaminedisuccinic acid (EDDS), ethylenediaminetetraacetic acid (EDTA), and nitrilotriacetic acid (NTA) were studied. Mobility of metal in the samples was evaluated by using a sequential extraction scheme that could give the information needed to explain different extraction efficiencies for different metals. Results of long-term leaching tests of CCA-treated wood before and after EDDS extraction were used to evaluate Cr, Cu, and As leachability. Kinetic experiments showed that 6 h was the optimum extraction time for all metals and CCA-treated wood. Experimental results showed that EDDS is a very effective chelating agent for the extraction of Cr, Cu, and As from CCA-treated wood. Increased temperature significantly enhanced the extraction efficiency of CCA metals, especially Cr and As. The much better extractability of Cu compared to Cr and As by chelating agents can be attributed to the presence of larger weakly bound fractions. The CCA-treated woods after EDDS extraction have met the EPA's TCLP regulatory limit and could be classified as a non-hazardous waste according to identification standard of hazardous wastes.",
Arsenic,1015854,"Comparison of two adsorbents for the removal of pentavalent arsenic from aqueous solutions Abstract: Two adsorbents, magnesia-loaded fly ash cenospheres (MGLC) and manganese-loaded fly ash cenospheres (MNLC), were prepared by wet impregnation of fly ash cenospheres with MgCl(2) solution or a mixed solution of MnCl(2) and KMnO(4), respectively. Their physicochemical properties were characterized by scanning electron microscopy, X-ray diffractometry, X-ray fluorescence spectrometry, and Fourier transform infrared spectrometry. Sorption experiments were conducted to examine the effects of adsorbent dosage, pH, time, temperature, ionic strength and competing anions on As(V) removal by MGLC and MNLC. Both MGLC and MNLC had greater pH buffering capacity and were less affected by changes in ionic strength. Competing anions (carbonate and dihydric phosphate) had a larger impact on As(V) removal by MNLC than by MGLC. Adsorption on MNLC reached equilibrium at 60 min, while adsorption on MGLC reached equilibrium at 120 min. The Langmuir adsorption isotherm was a good fit for the experimental data of As(V) adsorption on MGLC and MNLC, and the adsorption kinetics for both followed the pseudo-second-order rate equation. MGLC and MNLC had a larger removal capacity for As(V) than the cenospheres. Compared with MNLC, MGLC is a better absorbent.",
Arsenic,1347766,"Cellular and biochemical effects induced by atrazine on blood of male Japanese quail (Coturnix japonica) Abstract: Atrazine a potent endocrine disruptor herbicide is broadly used to control rapidly growing unwanted weeds in various cereals crops which induce adverse effects both in mammalian and avian species. In present study 96 mature male Japanese quail (Coturnix japonica) were procured and randomly kept in eight groups (A to H) each having 12 birds. Atrazine was administered orally at 0, 10, 25, 50, 100, 250 and 500 mg/kg body weight to all experimental groups. The mitomycin C at 2 mg/kg body weight was given to the birds of group B which served as a positive control. From each group 4 birds were randomly selected and harvested at day 15, 30 and 45. A significant (P < 0.05) decrease in serum total protein, serum albumin and serum testosterone values were recorded at day 45 in all treated groups. A significant increase in serum ALT and AST concentration was also recorded. Moreover, morphological alterations in nucleus of erythrocytes were also observed including blebbed nuclei, notched nuclei, lobed nuclei, vacuolated cells, binucleated cell, and cell with pear shaped and micronucleus. Overall, our results show that atrazine at higher doses induces significant serum biochemical alterations and changes in nucleus of erythrocytes.",
Arsenic,1175745,"Effects of low-dose drinking water arsenic on mouse fetal and postnatal growth and development Abstract: <strong>BACKGROUND: </strong>Arsenic (As) exposure is a significant worldwide environmental health concern. Chronic exposure via contaminated drinking water has been associated with an increased incidence of a number of diseases, including reproductive and developmental effects. The goal of this study was to identify adverse outcomes in a mouse model of early life exposure to low-dose drinking water As (10 ppb, current U.S. EPA Maximum Contaminant Level).<br /><br /><strong>METHODOLOGY AND FINDINGS: </strong>C57B6/J pups were exposed to 10 ppb As, via the dam in her drinking water, either in utero and/or during the postnatal period. Birth outcomes, the growth of the F1 offspring, and health of the dams were assessed by a variety of measurements. Birth outcomes including litter weight, number of pups, and gestational length were unaffected. However, exposure during the in utero and postnatal period resulted in significant growth deficits in the offspring after birth, which was principally a result of decreased nutrients in the dam's breast milk. Cross-fostering of the pups reversed the growth deficit. Arsenic exposed dams displayed altered liver and breast milk triglyceride levels and serum profiles during pregnancy and lactation. The growth deficits in the F1 offspring resolved following separation from the dam and cessation of exposure in male mice, but did not resolve in female mice up to six weeks of age.<br /><br /><strong>CONCLUSIONS/SIGNIFICANCE: </strong>Exposure to As at the current U.S. drinking water standard during critical windows of development induces a number of adverse health outcomes for both the dam and offspring. Such effects may contribute to the increased disease risks observed in human populations.",
Arsenic,1379881,"Slurry atomization for the determination of arsenic in baby foods using electrothermal atomic absorption spectrometry and deuterium background correction Abstract: BIOSIS COPYRIGHT: BIOL ABS. A procedure for accurately determining arsenic in different types of baby foods using slurried samples is developed. Compensation of the background is carried out using a deuterium device. Suspensions prepared in a medium containing 0.1% m/v Triton X-100, 20% v/v concentrated hydrogen peroxide, 1% v/v concentrated nitric acid and 0.3% m/v nickel nitrate are directly introduced into the furnace. The calcination and atomization temperatures are 1400 and 2400 ?C, respectively. Calibration is carrie",
Arsenic,1250989,"Desulfuribacillus alkaliarsenatis gen. nov. sp. nov., a deep-lineage, obligately anaerobic, dissimilatory sulfur and arsenate-reducing, haloalkaliphilic representative of the order Bacillales from soda lakes Abstract: An anaerobic enrichment culture inoculated with a sample of sediments from soda lakes of the Kulunda Steppe with elemental sulfur as electron acceptor and formate as electron donor at pH 10 and moderate salinity inoculated with sediments from soda lakes in Kulunda Steppe (Altai, Russia) resulted in the domination of a Gram-positive, spore-forming bacterium strain AHT28. The isolate is an obligate anaerobe capable of respiratory growth using elemental sulfur, thiosulfate (incomplete reduction) and arsenate as electron acceptor with H(2), formate, pyruvate and lactate as electron donor. Growth was possible within a pH range from 9 to 10.5 (optimum at pH 10) and a salt concentration at pH 10 from 0.2 to 2 M total Na(+) (optimum at 0.6 M). According to the phylogenetic analysis, strain AHT28 represents a deep independent lineage within the order Bacillales with a maximum of 90 % 16S rRNA gene similarity to its closest cultured representatives. On the basis of its distinct phenotype and phylogeny, the novel haloalkaliphilic anaerobe is suggested as a new genus and species, Desulfuribacillus alkaliarsenatis (type strain AHT28(T) = DSM24608(T) = UNIQEM U855(T)).",
Arsenic,1017521,"Community exposure to arsenic in the Mekong River delta, Southern Vietnam Abstract: We examined the daily inorganic arsenic (i-As) intake from drinking water and rice in 45 households (75 individuals) in the An Giang province, Southern Vietnam. The daily i-As intake ranged from 28-102 ?g d(-1), equivalent to the daily dose of 0.6-1.9 ?g d(-1) kg((body wt))(-1). Increased As concentrations were observed in human hair in the study location. Approximately 67% (n = 44), 42% (n = 28), and 15% (n = 10) of the hair samples had As levels exceeding 1, 3, and 10 ?g g(-1), respectively. The total As concentrations in female and male hair correlated well with the total daily i-As intake. Measurement of As concentrations in the hair of people who were consuming or had previously consumed As from contaminated sources may help predict the onset of negative health effects. We suggested an application of the Bayes's theorem to calculate the probability that an individual in a population will acquire a negative health effect, given that the concentration of arsenic in the subject's hair has been determined.",
Arsenic,1423123,"Micro-analytical characterisation of radioactive heterogeneities in samples from Central Asian TENORM sites Abstract: The present work focuses on the use of micro-analytical techniques to demonstrate the heterogeneous distribution of radionuclides and metals in soils collected at Former Soviet Union mining sites in Central Asia. Based on digital autoradiography, radionuclides were heterogeneously distributed in soil samples collected at the abandoned uranium mining sites Kurday, Kazakhstan, Kadji Sai, Kyrgyzstan and Taboshar, Tajikistan. Using electron microscopy interfaced with X-ray microanalysis submicron - mm-sized radioactive particles and rock fragments with U, As, Se and toxic metals on the surfaces were identified in Kurday and Kadji Sai samples. Employing scanning and tomographic (3D) synchrotron radiation based micro-X-ray fluorescence (?-SRXRF) and synchrotron radiation based micro-X-ray diffraction (?-SRXRD) allowed us to observe the inner structure of the particles without physical sectioning. The distribution of elements in virtual crosssections demonstrated that U and a series of toxic elements were rather heterogeneously distributed also within individual radioactive TENORM particles. Compared to archived data, U in Kadji Sai particles was present as uraninite (U(4)O(9+y) or UO(2+x)) or Na-zippeite ((Na(4)(UO(2))(6)[(OH)(10)(SO(4))(3)]·4H(2)O), i.e. U minerals with very low solubility. The results suggested that TENORM particles can carry substantial amount of radioactivity, which can be subject to re-suspension, atmospheric transport and water transport. Thus, the potential radioecological and radioanalytical impact of radioactive particles at NORM and TENORM sites worldwide should be taken into account. The present work also demonstrates that radioecological studies should benefit from the use of advanced methods such as synchrotron radiation based techniques.",
Arsenic,1252404,"Lowering extracellular calcium content protects cells from arsenite-induced killing and micronuclei formation Abstract: The present study demonstrated that calcium ions were accumulated in nuclei of Chinese hamster ovary (CHO)-K1 cells after arsenite treatment. This process was enhanced by verapamil (a calcium channel blocker). Verapamil also significantly increased the cytotoxic effects of arsenite. In contrast, ethylene glycol-bis[beta-aminoethylether] N,N, N1,N1,-tetraacetic acid (EGTA, a calcium-specific chelator), or calcium-free conditions significantly reduced the cytotoxicity or arsenite. Similarly, the strategy of lowering extracellular calcium concentration by modifying the medium or lowering intracellular calcium concentration by administration of the intracellular calcium chelator quin 2, protected cells from arsenite-induced micronuclei formation. These data indicate that the disturbances in intracellular calcium homeostasis maybe involved in arsenite-induced cytotoxicity and micronuclei formation.",
Arsenic,2088304,"Long-term biomonitoring of soil contamination using poplar trees: Accumulation of trace elements in leaves and fruits Abstract: Phytostabilization aims to immobilize soil contaminants using higher plants. The accumulation of trace elements in Populus alba leaves was monitored for 12 years after a mine spill. Concentrations of As and Pb significantly decreased, while concentrations of Cd and Zn did not significantly over time. Soil concentrations extracted by CaCl2 were measured by ICP-OES and results of As and Pb were below the detection limit. Long-term biomonitoring of soil contamination using poplar leaves was proven to be better suited for the study of trace elements. Plants suitable for phytostabilization must also be able to survive and reproduce in contaminated soils. Concentrations of trace elements were also measured in P. alba fruiting catkins to determine the effect on its reproduction potential. Cadmium and Zn were found to accumulate in fruiting catkins, with the transfer coefficient for Cd significantly greater than Zn. It is possible for trace elements to translocate to seed, which presents a concern for seed germination, establishment and colonization. We conclude that white poplar is a suitable tree for long-term monitoring of soil contaminated with Cd and Zn, and for phytostabilization in riparian habitats, although some caution should be taken with the possible effects on the food web. Supplemental materials are available for this article. Go to the publisher's online edition of International Journal of Phytoremediation to view the supplemental file.",
Arsenic,1337516,"Urine arsenic and prevalent albuminuria: Evidence from a population-based study Abstract: BACKGROUND: Long-term arsenic exposure is a major global health problem. However, few epidemiologic studies have evaluated the association of arsenic with kidney measures. Our objective was to evaluate the cross-sectional association between inorganic arsenic exposure and albuminuria in American Indian adults from rural areas of Arizona, Oklahoma, and North and South Dakota. STUDY DESIGN: Cross-sectional. SETTING & PARTICIPANTS: Strong Heart Study locations in Arizona, Oklahoma, and North and South Dakota. 3,821 American Indian men and women aged 45-74 years with urine arsenic and albumin measurements. PREDICTOR: Urine arsenic. OUTCOMES: Urine albumin-creatinine ratio and albuminuria status. MEASUREMENTS: Arsenic exposure was estimated by measuring total urine arsenic and urine arsenic species using inductively coupled plasma mass spectrometry (ICPMS) and high-performance liquid chromatography-ICPMS, respectively. Urine albumin was measured by automated nephelometric immunochemistry. RESULTS: The prevalence of albuminuria (albumin-creatinine ratio ?30 mg/g) was 30%. Median value for the sum of inorganic and methylated arsenic species was 9.7 (IQR, 5.8-15.6) ?g per gram of creatinine. Multivariable-adjusted prevalence ratios of albuminuria (albumin-creatinine ratio ?30 mg/g) comparing the 3 highest to lowest quartiles of the sum of inorganic and methylated arsenic species were 1.16 (95% CI, 1.00-1.34), 1.24 (95% CI, 1.07-1.43), and 1.55 (95% CI, 1.35-1.78), respectively (P for trend <0.001). The association between urine arsenic and albuminuria was observed across all participant subgroups evaluated and was evident for both micro- and macroalbuminuria. LIMITATIONS: The cross-sectional design cannot rule out reverse causation. CONCLUSIONS: Increasing urine arsenic concentrations were cross-sectionally associated with increased albuminuria in a rural US population with a high burden of diabetes and obesity. Prospective epidemiologic and mechanistic evidence is needed to understand the role of arsenic as a kidney disease risk factor.",
Arsenic,120524,"Residential exposure to drinking water arsenic in Inner Mongolia, China Abstract: In the Ba Men region of Inner Mongolia, China, a high prevalence of chronic arsenism has been reported in earlier studies. A survey of the arsenic contamination among wells from groundwater was conducted to better understand the occurrence of arsenic (As) in drinking water. A total of 14,866 wells (30% of all wells in the region) were analyzed for their arsenic-content. Methods used to detect arsenic were Spectrophotometric methods with DCC-Ag (detection limit, 0.5 ?g of As/L); Spot method (detection limit, 10 ?g of As/L); and air assisted Colorimetry method (detection limit, 20 ?g of As/L). Arsenic-concentrations ranged from below limit of detection to 1200 ?g of As/L. Elevated concentrations were related to well depth (10 to 29 m), the date the well was built (peaks from 1980–1990), and geographic location (near mountain range). Over 25,900 individuals utilized wells with drinking water arsenic concentrations above 20 ?g of As/L (14,500 above 50 ?g of As/L—the current China national standard in drinking water and 2198 above 300 ?g of As/L). The presented database of arsenic in wells of the Ba Men region provides a useful tool for planning future water explorations when combined with geological information as well as support for designing upcoming epidemiological studies on the effects of arsenic in drinking water for this region.",
Arsenic,1337488,"PS(2)Br and AsS(2)X (X = Br, I): similar molecules with completely different shapes - a combined experimental and theoretical study Abstract: By the reaction of solid As(4)S(4) with gaseous Br(2) at a temperature of 410 K gaseous AsSBr and AsS(2)Br are formed; the reaction with gaseous I(2) at 468 K leads to the formation of AsSI, AsS(2)I, As(2)S(2)I(2) and As(2)S(3)I(2). Thermodynamic data on these novel species are obtained by mass spectrometry. The experimental findings are extended and confirmed by ab initio quantum chemical calculations. Undoubtedly the molecules AsSX (X = Br, I) and As(2)S(2)I(2) contain As-atoms in the formal oxidation state III. Unexpectedly, in AsS(2)X arsenic is not of formal oxidation state +V but +III: due to the absence of As-S ?-bonding, the molecular structure of AsS(2)X is arranged as a dithia-arsirane with an AsS(2) three-membered ring. For comparison with AsS(2)X, PS(2)Br is investigated for the first time. This high temperature species is planar with symmetry C(2v) and phosphorus of the formal oxidation state +V in which the two P[double bond, length as m-dash]S ?-bonds are realized due to their strength over one S-S ?-bond. As(2)S(3)I(2) contains a five-membered As(2)S(3)-ring with one S-S-bond. The ionization energies are determined and compared with those obtained from calculations; they serve as a further indication for the structures realized in these molecules.",
Arsenic,627171,"Sodium arsenite retards proliferation of PHA-activated T cells by delaying the production and secretion of IL-2 Abstract: Arsenic is a metalloid that commonly contaminates drinking water, and is a known human carcinogen. It has been shown that peripheral blood mononuclear cells (PBMCs) from healthy donors treated in vitro with NaAsO(2) and stimulated with phytohemagglutinin (PHA) show a lower proliferation than nontreated cells. We reported previously a reduction in the secretion of IL-2 in NaAsO(2)-treated PBMCs stimulated with PHA, an observation that might explain, in part, the reduction in proliferation. Since arsenic induces cytoskeleton alterations, which in turn may affect protein transport of the cell, we assumed that NaAsO(2) induced an accumulation of IL-2 inside the cells, and thus a reduction in the secretion of IL-2. In order to demonstrate this hypothesis, we assessed the intracellular IL-2 at the single cell level by flow cytometry, and unexpectedly found a reduction in the percentage of IL-2 producing T cells in the presence of NaAsO(2). We tracked the proliferation of T cells by using the 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dye and found that NaAsO(2) slows down the entrance to cell division and delays the proliferation of cells that have already entered the cell cycle. Nevertheless, the expression of the activation molecules, CD25 and CD69, was unaltered. Assessment of the intracellular and secreted IL-2 in kinetic experiments showed that in fact, NaAsO(2) delays the production of IL-2, given that a recovery of both intracellular and secreted IL-2 was detected at 72 h. Evaluation of the cell cycle showed a higher proportion of cells in G(0)/G(1) and a lower proportion in G(2)/M in the presence of NaAsO(2). We thus conclude that NaAsO(2) reduces proliferation of T cells by delaying the production and secretion of IL-2, thus blocking T cells in G(1); as a consequence, the entry to cell cycle and the rounds of cell division are retarded, and a lower proliferation of T cells is hence observed.",
Arsenic,1508610,"Determination of lead, cadmium and arsenic in infusion tea cultivated in north of Iran Abstract: Tea is one of the most common drinks in all over the world. Rapid urbanization and industrialization in recent decades has increased heavy metals in tea and other foods. In this research, heavy metal contents such as lead (Pb), cadmium (Cd) and arsenic (As) were determined in 105 black tea samples cultivated in Guilan and Mazandaran Provinces in north of Iran and their tea infusions. The amount of heavy metals in black tea infusions were analyzed using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP - AES).The mean?±?SD level of Pb in 5, 15 and 60 min in infusion tea samples were 0.802?±?0.633, 0.993?±?0.667 and 1.367?±?1.06 mg/kg of tea dry weight, respectively. The mean level of Cd in 5, 15 and 60 min in infusion tea samples were 0.135?±?0.274, 0.244?±?0.46 and 0.343?±?0.473 mg/kg of tea dry weight, respectively. The mean level of As in 5, 15 and 60 min in infusion tea samples were 0.277?±?0.272, 0.426?±?0.402 and 0.563?±?0.454 mg/kg of tea dry weight, respectively. Also, the results showed that the locations and the infusion times influenced upon the amount of these metals (P?&lt;?0.05).",
Arsenic,1346313,"Induction of heme oxygenase-1 in LMH cells. Comparison of LMH cells to primary cultures of chick embryo liver cells Abstract: Heme oxygenase catalyzes the degradation of heme into biliverdin, carbon monoxide, and iron. Two forms of this enzyme, heme oxygenase-1 and -2, have been identified; only heme oxygenase-1 is subject to induction by heme, metal ions, and other chemical and physical perturbations (e.g. drugs, oxidants, and heat shock). Primary chick embryo liver cells are widely used for the study of heme metabolism because of their ease of preparation, low cost, and high degree of similarity to human heme metabolism. Nonetheless, this system has some limitations: new cultures must be prepared every week; the resulting cell populations are non-homogeneous; and cells are short-lived, limiting the feasible duration of time course and transfection studies. LMH cells are the first chicken hepatoma cell line to be established. The aim of this study was to characterize the regulation of heme oxygenase-1 in LMH cells, and to compare this regulation to that previously described in primary chick embryo liver cells. The induction of heme oxygenase-1 was assessed by measuring changes in mRNA levels or enzyme activities in response to several treatments, including heme, heavy metals, sodium arsenite, and heat shock, which have been shown to increase the expression of heme oxygenase. Similarities were observed with respect to regulation of heme oxygenase-1 expression in primary hepatocytes and LMH cells. We report the first measurable heat shock response of heme oxygenase-1 in CELC or LMH cells; and show that LMH cells are a useful model for the study of heme oxygenase-1 regulation.",
Arsenic,1019929,"Arsenobetaine is not a major metabolite of arsine gas in the rat Abstract: Many organisms can easily dispose of toxic inorganic arsenic species through gradual methylation of the element and further urinary excretion. In order to clarify the urinary excretion of arsenobetaine observed in a human case of intoxication by arsine, the capacity of highly methylated arsenical synthesis has been investigated in rats acutely exposed during 1 h to increasing concentrations of the same gas [4 to 80 mg AsH3/m3]. Urinary metabolites of arsenic were determined with good agreement in two (Belgian and Italian) laboratories using two different analytical procedures. The sum of inorganic, mono- and dimethylated metabolites of arsenic in urine was shown to be related to the intensity of exposure to arsine. A biphasic relationship was observed: 1 h exposure to &gt; 60 mg AsH3/m3 led to metabolite excretion which is roughly 10 times higher than for exposure levels below that limit, suggesting the saturation of a binding site reserve and the availability for metabolism of a greater proportion of the As absorbed above this threshold. Arsenobetaine production, if any, could only be detected when its presence in food was excluded; in addition, amounts appeared negligible and could be disregarded as a common arsenic metabolite in rats.",
Arsenic,1509356,Arsenic Accumulation and Tolerance of Cytisus scoparius Under Controlled Conditions Abstract: ,
Arsenic,593080,"Gene expression profiling analysis reveals arsenic-induced cell cycle arrest and apoptosis in p53-proficient and p53-deficient cells through differential gene pathways Abstract: Arsenic (As) is a well-known environmental toxicant and carcinogen as well as an effective chemotherapeutic agent. The underlying mechanism of this dual capability, however, is not fully understood. Tumor suppressor gene p53, a pivotal cell cycle checkpoint signaling protein, has been hypothesized to play a possible role in mediating As-induced toxicity and therapeutic efficiency. In this study, we found that arsenite (As3+) induced apoptosis and cell cycle arrest in a dose-dependent manner in both p53+/+ and p53-/- mouse embryonic fibroblasts (MEFs). There was, however, a distinction between genotypes in the apoptotic response, with a more prominent induction of caspase-3 in the p53-/- cells than in the p53+/+ cells. To examine this difference further, a systems-based genomic analysis was conducted comparing the critical molecular mechanisms between the p53 genotypes in response to As3+. A significant alteration in the Nrf2-mediated oxidative stress response pathway was found in both genotypes. In p53+/+ MEFs, As3+ induced p53-dependent gene expression alterations in DNA damage and cell cycle regulation genes. However, in the p53-/- MEFs, As3+ induced a significant up-regulation of pro-apoptotic genes (Noxa) and down-regulation of genes in immune modulation. Our findings demonstrate that As-induced cell death occurs through a p53-independent pathway in p53 deficient cells while apoptosis induction occurs through p53-dependent pathway in normal tissue. This difference in the mechanism of apoptotic responses between the genotypes provides important information regarding the apparent dichotomy of arsenic's dual mechanisms, and potentially leads to further advancement of its utility as a chemotherapeutic agent.",
Arsenic,627061,"The correlation of arsenic levels in drinking water with the biological samples of skin disorders Abstract: Arsenic (As) poisoning has become a worldwide public health concern. The skin is quite sensitive to As and skin lesions are the most common and earliest nonmalignant effects associated to chronic As exposure. In 2005–2007, a survey was carried out on surface and groundwater arsenic contamination and relationships between As exposure via the drinking water and related adverse health effects (melanosis and keratosis) on villagers resides on the banks of Manchar lake, southern part of Sindh, Pakistan. We screened the population from arsenic-affected villages, 61 to 73% population were identified patients suffering from chronic arsenic toxicity. The effects of As toxicity via drinking water were estimated by biological samples (scalp hair and blood) of adults (males and females), have or have not skin problem (n=187). The referent samples of both genders were also collected from the areas having low level of As (b10 ?g/L) in drinking water (n=121). Arsenic concentration in drinking water and biological samples were analyzed using electrothermal atomic absorption spectrometry. The range of arsenic concentrations in lake surface water was 35.2–158 ?g/L, which is 3–15 folds higher than World Health Organization [WHO, 2004. Guidelines for drinking-water quality third ed., WHO Geneva Switzerland.]. It was observed that As concentration in the scalp hair and blood samples were above the range of permissible values 0.034–0.319 ?g As/g for hair and b0.5–4.2 ?g/L for blood. The linear regressions showed good correlations between arsenic concentrations in water versus hair and blood samples of exposed skin diseased subjects (R2=0.852 and 0.718) as compared to non-diseased subjects (R2=0.573 and 0.351), respectively.",
Arsenic,1354510,DETERMINATION OF ARSENIC IN GLYCERIN BY HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROSCOPY Abstract: ,
Arsenic,1508652,How bacteria choose phosphate Abstract: Discriminating against arsenate: Determination of the structure of periplasmic phosphate binding proteins at very high resolution provides the basis for understanding the high discrimination of bacteria against arsenate. The results complete our insight into earlier erroneous conclusions on the ability of certain bacteria to use arsenate instead of phosphate.,
Arsenic,1022954,"Urinary sulfur-containing metabolite produced by intestinal bacteria following oral administration of dimethylarsinic acid to rats Abstract: Our long-term oral administration of dimethylarsinic acid (DMAV) in rats revealed that three unidentified metabolites, M-1, M-2, and M-3, were detected in urine and feces. DMAV and trimethylarsine oxide (TMAO) were converted to M-2 and M-3 and M-1 by Escherichia coli strain A3-6 isolated from the ceca of DMAV-administered rats, respectively. In this study, we report on the mechanism of production and the chemical properties of these unknown metabolites. To investigate the pattern of conversion of DMAV or TMAO by A3-6 in the presence of cysteine (Cys), arsenic metabolites of DMAV or TMAO in medium after incubation with A3-6 and Cys were analyzed by liquid chromatography with inductively coupled plasma mass spectrometry (LC-ICP-MS). DMAV was reduced to dimethylarsinous acid (DMAIII) to form M-2 in the presence of Cys and A3-6, and M-2 was further converted to M-3. TMAO was rapidly converted to M-1 by A3-6. The cytotoxicity of the unidentified metabolites was investigated. M-2 was more cytotoxic than DMAV, M-1, and M-3 in V79 cells. The cytotoxicity of M-2 in HL-60 cells was decreased by the addition of superoxide dismutase, suggesting that the cytotoxicity of M-2 might be due to the production of reactive oxygen species. In addition, we examined the chemical properties of M-2 by LC-ICP-MS and LC-MS. M-2 was oxidized to DMAV by hydrogen peroxide, suggesting that M-2 may be a reduced form of DMAV. M-2 was consistent with the reactant of DMAV with metabisulfite-thiosulfate reagent but not DMAIII by analyses of LC-ICP-MS and LC-MS. The molecular weight of M-2 was 154, and M-2 was a sulfur-containing metabolite.",
Arsenic,1347903,"Enhancement of expression of stress proteins by agents that lower the levels of glutathione in cells Abstract: The effects of diethyl maleate and buthionine sulfoximine, agents that lower cellular levels of glutathione, on expression of hsp27 and alphaB crystallin in response to stress were studied. When C6 rat glioma cells were treated with 100 microM arsenite for 1 h, accumulation of the two proteins, estimated by specific immunoassays, was markedly enhanced by additional exposure to 1 mM diethyl maleate or 2.5 mM buthionine sulfoximine. The latter also increased heat- and CdCl2-induced accumulation of hsp27 and alphaB crystallin. Stress-induced accumulation of hsp70, estimated by Western blotting analysis, was also enhanced by these agents. Northern blotting analysis revealed increase in levels of mRNAs for hsp27, alphaB crystallin and hsp70. The period of heat shock element (HSE)-binding activity of heat shock factor (HSF) stimulated by arsenite was extended by addition of diethyl maleate and buthionine sulfoximine. The induced phosphorylated state of HSF1 was also prolonged by diethyl maleate. Although exposure of cells to diethyl maleate alone for 1 h caused neither accumulation of hsp27, alphaB crystallin and hsp70 nor expression of mRNAs for these proteins, HSE-binding activity of HSF was stimulated. However, the activated HSF was not phosphorylated. These results suggest that diethyl maleate induces an intermediate state of HSF that binds to HSE but is transcriptionally inert. The mechanism is unclear but the levels of glutathione in cells that were exposed to diethyl maleate or buthionine sulfoximine were markedly decreased.",1
Arsenic,1508549,"Differences in the Accumulation and Distribution Profile of Heavy Metals and Metalloid between Male and Female Crayfish (Astacus leptodactylus) Abstract: Concentrations of selected heavy metals and a metalloid were measured by ICP-MS in crayfish (Astacus leptodactylus) collected from Lake Hirfanli, Turkey. Aluminum (Al), chromium ((52)Cr, (53)Cr), copper ((63)Cu, (65)Cu), manganese (Mn), nickel (Ni) and arsenic (As) were measured in the exoskeleton, gills, hepatopancreas and abdominal muscle tissues of 60 crayfish of both genders. With the exception of Al, differences were determined between male and female cohorts for the accumulation trends of the above-mentioned elements in the four tissues. It was also noted that the accumulation rates of Ni and As were significantly lower in gill tissue of females compared to males and no significant difference was observed for Cu isotopes in female crayfish. Cluster Analysis (CA) recovered similar results for both genders, with links between accumulations of Ni and As being notable. Accumulation models were described separately for male and female crayfish using regression analysis, and are presented for models where R(2) &gt; 0.85.",
Arsenic,1386834,"Effects of pesticides on owls in North America Abstract: A literature review of the effects of pesticides on owls in North America showed that relatively few studies have been undertaken. Owls used in experiments seem as sensitive to organochlorine pesticides (OCs) as other birds of prey, but wild owls experienced few serious problems, primarily because they were exposed to lower residues in their predominately mammalian or invertebrate prey. For example, the great horned owl ( Bubo virginianus ) and the common barn-owl ( Tyto alba ) neither experienced marked changes in mortality or recruitment rates nor was there any evidence of population decreases even during the maximum period of OC pesticide use. Also, eggshell thinning was not a widespread problem. There were adverse effects on individual owls including verified records of 74 owls of six species that died from secondary or tertiary poisoning related to strychnine, organochlorines, anticholinesterases (antiChEs) and anticoagulants in 16 states within the U.S. and one province in Canada. Most of the pesticide-related deaths occurred during the 1980s, although this probably does not represent a true temporal distribution. Verified mortalities of owls probably represent a small fraction of the actual number that died from pesticides. Incidence of mortality seems biased geographically toward areas such as New York that have active ecotoxicological programs. Burrowing owl ( Speotyto cunicularia ) populations currently are decreasing throughout much of the range in the U.S. and Canada. Studies in Canada indicate that antiChE pesticides, particularly carbofuran, were responsible for the declines there.",
Arsenic,1017910,"The positive response of Ty1 retrotransposition test to carcinogens is due to increased levels of reactive oxygen species generated by the genotoxins Abstract: In previous laboratory and environmental studies, the Ty1 short-term test showed positive responses (i.e. induced mobility of the Ty1 retrotransposon) to carcinogenic genotoxins. Here, we provide evidence for a causal relationship between increased level of reactive oxygen species and induction the mobility of the Ty1 retrotransposon. Results obtained in concentration and time-dependent experiments after treatment, the tester cells with carcinogenic genotoxins [benzo(a)pyrene, benzo(a)anthracene, ethylmethanesulfonate, formamide], free bile acids (chenodeoxycholic, lithocholic acids) and metals (arsenic, hexavelant chromium, lead) showed a simultaneous increase in both cellular level of the superoxide anions and Ty1 retrotransposition rates. Treatment with the noncarcinogenic genotoxins [benzo(e)pyrene, benzo(b)anthracen, anthracene], conjugated bile acids (taurodeoxycholic, glycodeoxycholic acids) and metals (zinc, trivalent chromium) did not change significantly superoxide anions level and Ty1 retrotransposition rate. The induction by carcinogens of the Ty1 mobility seems to depend on the accumulation of superoxide anions, since the addition of the scavenger N-acetylcysteine resulted in loss of both increased amount of superoxide anions and induced Ty1 retrotransposition. Increased hydrogen peroxide levels are also involved in the induction of Ty1 retrotransposition rates in response to treatment with carcinogenic genotoxins, as evidenced by disruption of YAP1 gene in the tester cells. It is concluded that the carcinogen-induced high level of reactive oxygen species play a primary and key role in determination the selective response of Ty1 test to carcinogenic genotoxins.",
Arsenic,2347560,"History of metal contamination in Lake Illawarra, NSW, Australia Abstract: Lake Illawarra has a long history of sediment contamination, particularly by metals, as a result of past and current industrial operations and land uses within the catchment. In this study, we examined the history of metal contamination in sediments using metal analysis and (210)Pb and (137)Cs dating. The distributions of copper, zinc, arsenic, selenium, cadmium and lead concentrations within sediment cores were in agreement with historical events in the lake, and indicated that metal contamination had been occurring since the start of industrial activities in Port Kembla in the late 1800s. Most metal contamination, however, has occurred since the 1960s. Sedimentation rates were found to be 0.2cmyear(-1) in Griffins Bay and 0.3cmyear(-1) in the centre of the lake. Inputs from creeks bringing metals from Port Kembla in the northeast of the lake and a copper slag emplacement from a former copper refinery on the Windang Peninsula were the main sources of metal inputs to Lake Illawarra. The metals of highest concern were zinc and copper, which exceeded the Australian and New Zealand sediment quality guideline values at some sites. Results showed that while historical contamination persists, current management practices have resulted in reduced metal concentrations in surface sediments in the depositional zones in the centre of the lake.",
Arsenic,1519084,"Nerve growth factor (NGF) exhibits an antioxidant and an autocrine activity in mouse liver that is modulated by buthionine sulfoximine, arsenic and acetominophen Abstract: ABSTRACT Nerve growth factor (NGF) is one of several structurally related proteins, named neurotrophins (NTs), that regulate neuronal survival, development, function, and plasticity. Moreover, NGF is an important activator of antioxidant mechanisms. These NGF functions are mediated by tropomyosin-related kinase receptor A (TrkA). Although NTs and their receptors have been shown to be expressed in visceral tissues, the extent to which NTs are involved in the physiology of visceral tissues is less clear. NGF is the most expressed NT in adult mouse livers. Although NGF is an important modulator of antioxidant mechanisms in neural tissues, few studies describe the relationship between oxidative stress and NGF expression in the liver. In the present study, we demonstrate that ngfb mRNA is positively modulated in mouse livers after oxidative injury via intraperitoneal injection of 14 mg/kg sodium arsenite, 6 mmol/kg L-buthionine-S-R-sulfoximine (BSO) or 300 mg/kg acetaminophen (APAP). In addition to the up regulation of ngfb we observed the phosphorylation of the NGF high-af?nity receptor TrkA in the liver as well as downstream phosphorylation of Akt, NF-kB nuclear migration and i?b? and tx-1 mRNA up regulation. These effects were abolished when a neutralizing anti-NGF antibody was used. Furthermore, this anti-NGF antibody alone induced oxidative stress in the liver by decreasing reduced glutathione, increasing oxidized glutathione and down regulating tx-1 mRNA. Thus, NGF plays a critical role in liver protection against oxidative stress and xenobiotic injury as well as maintaining a reduced thiol state.",
Arsenic,1027534,"Elevated ERCC1 gene expression in blood cells associated with exposure to arsenic from drinking water in Inner Mongolia Abstract: <strong>BACKGROUND: </strong>Chronic arsenic exposure has been associated with human cancer. The objective of this study was to investigate the effects of arsenic exposure on a DNA nucleotide excision repair gene, ERCC1, expression in human blood cells.<br /><br /><strong>PATIENTS AND METHODS: </strong>Water and toenail samples were collected from a total of 327 Inner Mongolian residents for arsenic analysis. Blood samples were collected to determine mRNA expression levels by real-time PCR.<br /><br /><strong>RESULTS: </strong>The mRNA levels of ERCC1 expression were positively associated with water arsenic concentration (slope=0.313, p=0.0043) and nail arsenic concentration (slope=0.474, p=0.0073). mRNA levels of ERCC1 expression were significantly correlated with those of OGG1, a base pair excision repair gene (r=0.275, p&lt;0.0001).<br /><br /><strong>CONCLUSION: </strong>The results showed that mRNA levels of ERCC1 expression were significantly associated with arsenic concentrations in drinking water, implicating the DNA repair response was induced by arsenic exposure.",
Arsenic,1348460,"Arsenic accumulation by aquatic macrophyte coontail (Ceratophyllum demersum L.) exposed to arsenite, and the effect of iron on the uptake of arsenite and arsenate Abstract: In this study, the aquatic macrophyte Ceratophyllum demersum L. (coontail or hornwort) was tested for its efficiency of arsenic (As) uptake under laboratory conditions. Our results revealed that the solution pH had a significant effect on As accumulation by C. demersum (p < 0.001). The accumulation was highest at pH 5 and decreased as pH values increased. Plants that were exposed to various concentrations of arsenite (As(III)) for 24 and 48 h, exhibited tolerance and toxic responses, respectively. As accumulation by C. demersum depended on the concentrations of As(III) and the duration of exposure (p < 0.001). At 40 ?M after 24 h, plants accumulated 227.5 ?g As g?1 dw and showed no visible symptoms of toxicity. However, after 48 h, As level reached 302.4 ?g g?1 dw and biomass production decreased significantly. Toxic effects were evident by plant necrosis and negative biomass production, leading to a decrease in the amount of accumulated As. Also, the addition of iron (Fe) into the nutrient solutions (0.18 mM) had contrasting effects on the uptake of 2 As species – the uptake of As(III) was enhanced by the presence of Fe, but the uptake of arsenate (As(V)) was considerably inhibited.",
Arsenic,710943,"Global gene expression profiling of hyperkeratotic skin lesions from inner Mongolians chronically exposed to arsenic Abstract: The skin is an organ that is highly sensitive to chronic arsenic (As) exposure. Skin lesions such as hyperkeratoses (HKs) are common early manifestations of arsenicosis in humans. HKs can be precursor lesions of nonmelanoma skin cancers (NMSCs), but the driving forces behind their formation and how they may ultimately progress to NMSCs are unknown. The goal of this study was to examine the global gene expression profiles of As-related HKs in an effort to better understand gene expression changes that are potentially associated with early stages of As carcinogenesis. HK biopsies were removed from individuals living in an arsenicosis-endemic region in Inner Mongolia who had been exposed to high As levels in their drinking water for &gt;20 years. Gene expression profiling was performed on RNA isolated from 7 individuals in this group and from 4 lesion-free skin samples from healthy individuals. Consistent with the pathological characteristics of the HK lesions, major functional categories and known canonical pathways represented by altered transcripts include those involved in development, differentiation, apoptosis, proliferation, and stress response. The results of this study may help define a signature profile of gene expression changes associated with long-term As exposure in the skin.",
Arsenic,1250965,"Growth of a bacterium that apparently uses arsenic instead of phosphorus is a consequence of massive ribosome breakdown Abstract: A recent report (Wolfe-Simon et al. (2011) Science 332, 1163-1166) described the isolation of a special bacterial strain, GFAJ-1, that could grow in medium containing arsenate, but lacking phosphate, and that supposedly could substitute As for P in its biological macromolecules. Here, we provide an alternative explanation for these observations, and show that they can be reproduced in a laboratory strain of Escherichia coli. We find that arsenate induces massive ribosome degradation, which provides a source of phosphate. A small number of arsenate-tolerant cells arise during the long-lag period prior to initiation of growth in + As/-P medium, and it is this population which undergoes the very slow, limited growth observed for both E. coli and GFAJ-1. These results provide a simple explanation for the reported growth of GFAJ-1 in arsenate without invoking replacement of phosphorus by arsenic in biological macromolecules.",
Arsenic,1070502,"Sodium arsenite represses the expression of myogenin in C2C12 mouse myoblast cells through histone modifications and altered expression of Ezh2, Glp, and Igf-1 Abstract: Arsenic is a toxicant commonly found in water systems and chronic exposure can result in adverse developmental effects including increased neonatal death, stillbirths, and miscarriages, low birth weight, and altered locomotor activity. Previous studies indicate that 20nM sodium arsenite exposure to C2C12 mouse myocyte cells delayed myoblast differentiation due to reduced myogenin expression, the transcription factor that differentiates myoblasts into myotubes. In this study, several mechanisms by which arsenic could alter myogenin expression were examined. Exposing differentiating C2C12 cells to 20nM arsenic increased H3K9 dimethylation (H3K9me2) and H3K9 trimethylation (H3K9me3) by 3-fold near the transcription start site of myogenin, which is indicative of increased repressive marks, and reduced H3K9 acetylation (H3K9Ac) by 0.5-fold, indicative of reduced permissive marks. Protein expression of Glp or Ehmt1, a H3-K9 methyltransferase, was also increased by 1.6-fold in arsenic-exposed cells. In addition to the altered histone remodeling status on the myogenin promoter, protein and mRNA levels of Igf-1, a myogenic growth factor, were significantly repressed by arsenic exposure. Moreover, a 2-fold induction of Ezh2 expression, and an increased recruitment of Ezh2 (3.3-fold) and Dnmt3a (~2-fold) to the myogenin promoter at the transcription start site (-40 to +42), were detected in the arsenic-treated cells. Together, we conclude that the repressed myogenin expression in arsenic-exposed C2C12 cells was likely due to a combination of reduced expression of Igf-1, enhanced nuclear expression and promoter recruitment of Ezh2, and altered histone remodeling status on myogenin promoter (-40 to +42).",
Arsenic,2088436,"Trichosanthes dioica fruit extract ameliorates arsenic-induced brain toxicity in male albino rats Abstract: This study evaluated the ameliorative potential of aqueous extract of Trichosanthes dioica fruit (AQTD) against arsenic-induced toxicity in rat brain. AQTD (50 and 100 mg/kg) was administered orally to male Wistar albino rats for 20 consecutive days before oral administration of sodium arsenite (10 mg/kg) for 8 days. We then evaluated the brain biochemical parameters viz. lipid peroxidation, reduced and oxidized glutathione, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and DNA fragmentation. Pretreatment with AQTD significantly and dose dependently modulated all the antioxidative parameters and reduced DNA fragmentation in rat brain intoxicated with arsenic. These findings conclude that T. dioica fruit possesses a remarkable ameliorative effect against arsenic-induced brain toxicity in male albino rats, which is mediated by alleviation of arsenic-induced oxidative stress by multiple mechanisms.",
Arsenic,1031306,"Expression of heat stress proteins by human periodontal ligament cells Abstract: The purpose of the present report was to document the stress response produced by physical and chemical abuses to human periodontal ligament cells, and to review some of the known functions of stress response proteins produced as a result of such treatments. For these studies human PDL cells were exposed to sublethal challenges of 43 degrees C heat, sodium arsenite and the amino acid analog L-azetidine-2-carboxylic acid (AZC). The cells were labelled with [35S]-methionine and the proteins produced were examined by autofluorography of SDS-PAGE gels. Heat challenges were shown to induce hsps with an apparent mol. wts. of 90K, 68-72K, 41-47K, and 36 K. Arsenite-treated cells produced similar hsps including a 30k protein not produced by other forms of stress. AZC treatment resulted in the production of apparent functionless hsps with apparent molecular weights of 90,000, 72,000, 68,000 and 36,000. The function of these proteins and their possible role in periodontal disease is discussed.",
Arsenic,1070333,"Determination of lead and arsenic in tobacco and cigarettes: an important issue of public health Abstract: Contents of lead and arsenic were determined in 617 tobacco samples and 80 samples of cigarettes. The mean content of lead in tobacco was 0.93 microg/g (range 0.02-8.56 microg/g) and arsenic was 0.15 microg/g (range < 0.02-2.04 microg/g). The mean content of lead in cigarettes was 1.26 microg/g (range 0.02-6.72 microg/g) and arsenic was 0.11 microg/g (range < 0.02-0.71 micro/g). There was a large variability in lead and arsenic content among samples of tobacco and samples of cigarettes. Positive correlation between lead and arsenic contents in tobacco was found (r = 0.22; p < 0.0001). Based on our data and data from literature we compare the content of lead and arsenic in tobacco and cigarettes in other studies and discuss the influence of smoking to lead and arsenic exposure and health. In conclusion, at the same time with the implementation of tobacco use prevention programmes it is advisable to implement continuous monitoring of lead and arsenic in tobacco and cigarettes in order to reduce the health risk due to exposure of these metals.",
Arsenic,2149107,"Current opinions about diagnosis and treatment strategy for aortic graft infections in The Netherlands Abstract: Aim: Aortic graft infection (AGI) is a dreaded complication in vascular surgery. Research on AGI is hampered by its rarity combined with a broad range of clinical presentation in critically ill patients. This report aims to explore the various current opinions on the diagnosis and treatment of AGI. Methods: A questionnaire was sent to all members of the Dutch Society of Vascular Surgery. Six weeks after the initial questionnaire a reminder was sent. A total of 306 questionnaires were sent. Data were analyzed for 124 vascular surgeons (VS) and 19 vascular surgeons in training (VT). Data analysis was performed in a descriptive manner. Results: Total response rate was 51.3%, Response rate of the VS and VT combined was 47%. 85% of the VS versus 58% of VT rely on computed tomography scanning (CT) scanning for diagnosing AGI. Positron emission tomography scanning with CT fusion was used by 40% of VS versus 58% of VT. Antibiotic treatment was started at the first suspicion of AGI by 52% of VS and 58% of VT. 13 different opinions were noted on total antibiotic duration. Extra-anatomic bypass (EAB) was used by and 42% of VT. In-situ reconstructions were used by 59% of VS versus % of VT. Venous reconstructions were the first reconstruction choice in 63% VS and 52% of VT. Antibiotic-bonded grafts were used by 17% of VS and 16% of VT. Conclusion: This survey shows highly mixed opinions about clinical diagnosis, diagnostic imaging, and treatment of AGI, reflecting available literature. Further research is therefore desperately needed. More research and development of treatment guidelines is needed to reach uniformity and consensus for patients with infected vascular grafts.",
Arsenic,1579366,"Arsenic speciation analysis in mono-varietal wines by on-line ionic liquid-based dispersive liquid-liquid microextraction Abstract: A highly efficient separation and pre-concentration method for arsenic species determination, based on ionic liquid (IL) dispersive microextraction technique implemented in a flow analysis system, is proposed. Highly selective separation of arsenite species [As(III)] was achieved by chelation with sodium diethyldithiocarbamate (DDTC) followed by dispersion with 40 mg of 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF(6)]) IL. Analyte extraction, retention and separation of IL phase were achieved with a packed microcolumn and As(III) was determined in eluent solution by electrothermal atomic absorption spectrometry (ETAAS). Concentration of As(V) was deduced by the difference between total inorganic arsenic and As(III). Thus, determination of total arsenic was performed by previous degradation of organo-arsenic species, followed by a reduction. Under optimal conditions, As(III) extraction efficiency was 100% and a sensitivity enhancement factor of 46 was obtained with only 4.0 ml of sample The method was successfully applied for arsenic speciation studies in mono-varietal wines.",
Arsenic,711053,"Urinary levels of arsenic and heavy metals in children and adolescents living in the industrialised area of Ria of Huelva (SW Spain) Abstract: The Ria of Huelva (south-west Spain) is a highly polluted estuary as a consequence of long-term mining and industrial activities. Between 2003 and 2004, we conducted a biomonitoring study of exposure to arsenic and some heavy metals (cadmium, chromium, copper and nickel) in urine samples of a representative sample (n=227) of children and adolescents residing in this area, and of a reference group of 196 children and adolescents living in other less industrialised areas of Andalusia (south Spain). We also assessed the determinants of the variability in urinary metals within the population of the Ria of Huelva. There were no significant differences in the concentration of metal compounds between the two groups with the exception of Cd levels, which were significantly higher in the reference group. Levels of the five metal ions in both groups were generally within the range of values reported by other biomonitoring studies for general children population, although mean Cd levels tended to be higher as compared to other European studies. Among the population of the Ria of Huelva, the main determinants of the interindividual variation in urinary metals were age, sex, area of residence, and frequency of intake of certain food items (mainly fish and shellfish). Overall, results suggest that living in the Ria of Huelva is not increasing current levels of exposure to certain metals among children and adolescents above those found in other urban areas of Andalusia.",
Arsenic,627310,"Effects of sodium arsenite on the cytoskeleton and cellular glutathione levels in cultured cells Abstract: The effects of As3+ (NaAsO2) on the microtubule and microfilament organization, cytoskeletal protein synthesis, cytoskeletal and cytosolic (soluble) protein sulfhydryls, and cellular glutathione (GSH) levels were examined in Swiss 3T3 mouse cells. Exposure of cells to 2.5 microM As3+ for 16 hr resulted in apparent cell retraction and loss of thick cables of actin filaments. However, the cells still retained numerous thinner microfilaments distributed in a disorganized manner. Microtubule organization was relatively undisturbed. At higher doses (greater than or equal to 20 microM), As3+ treatment caused a severe loss of microtubules and the remaining dense finer actin filaments formed smearing clusters in perinuclear areas. Treatment of cells with As3+ also induced a dose-dependent inhibition of cytoskeletal protein synthesis. Furthermore, As3+ exposure enhanced cellular GSH synthesis since the elevated cellular GSH content in As(3+)-treated cells could be abolished by treatment with buthionine sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase required for GSH biosynthesis. As determined by the N-[3H]-ethylmaleimide binding assay, As3+ exposure also increased the amount of protein sulfhydryls in both the cytoskeletal and the cytosolic protein fractions. Moreover, a greater increase in protein sulfhydryls occurred in the cytoskeletal fraction than in the soluble fraction. These results indicate that the cytoskeleton could be a cellular target for injury by As3+ exposure. The elevated cellular GSH content induced by As3+ could provide a protective mechanism against further injury from this metal insult.",
Arsenic,481292,"Risk assessment of arsenic mitigation options in Bangladesh Abstract: The provision of alternative water sources is the principal arsenic mitigation strategy in Bangladesh, but can lead to risk substitution. A study of arsenic mitigation options was undertaken to assess water quality and sanitary condition and to estimate the burden of disease associated with each technology in disability-adjusted life years (DALYs). Dugwells and pond-sand filters showed heavy microbial contamination in both dry and monsoon seasons, and the estimated burden of disease was high. Rainwater was of good quality in the monsoon but deteriorated in the dry season. Deep tubewells showed microbial contamination in the monsoon but not in the dry season and was the only technology to approach the World Health Organization's reference level of risk of 10(-6) DALYs. A few dugwells and one pond-sand filter showed arsenic in excess of 50 mu g/L. The findings suggest that deep tubewells and rainwater harvesting provide safer water than dugwells and pond-sand filters and should be the preferred options.",
Arsenic,1249010,"Analysis of arsenic bioaccumulation in different organs of the nutritionally important catfish, Clarias batrachus (L.) exposed to the trivalent arsenic salt, sodium arsenite Abstract: Pattern of arsenic bioaccumulation in six organ systems (blood, brain, gills, liver, muscles and skin) of Clarias batrachus was analysed following exposure to sublethal (1 mg L(-1); 5 % of 96 h LC(50) value) concentration of sodium arsenite. After 60 days of treatment the liver accumulated highest concentration (9.711 ± 0.138 ?g g(-1) dry wt of tissue.) of arsenic followed by gills (6.156 ± 0.154) &gt; blood (6.070 ± 0.043) &gt; muscles (5.756 ± 0.123) &gt; skin (5.606 ± 0.140) &gt; brain (2.350 ± 0.205). The bioaccumulations of arsenic in all the tissues were time dependant and increased with exposure period. Although the exposed fish loaded with arsenic did not die after prolonged treatment (60 days), the amount of arsenic accumulated made them unsuitable for human consumption. Due to depletion of the proteineous components of their muscles, the body mass of the exposed fish decreased without corresponding decrease in their length. This made the fish lean and thin. These proteineous moieties of the muscles and other tissue systems of the stressed fish were mobilized for breakdown to generate additional requirement of energy to combat the arsenic toxicity.",
Arsenic,2064181,"Activation of the ascorbate-glutathione cycle by nitric oxide: signaling under stress conditions induced by arsenic Abstract: The study evaluated the effect of nitric oxide (NO) in Pistia stratiotes exposed to arsenic (As), with NO supplied in the form of SNP. Plants were exposed to four treatments: control, SNP (0.1 mg L-1), As (1.5 mg L-1) and As + SNP (1.5 and 0.1 mg L(-)1, respectively), for 24 h. In plants exposed only to As, changes was observed in the concentration of reduced ascorbate. The addition of SNP altered the concentration of reduced ascorbate, dehydroascorbate and enzymes APX, DHAR and GR, indicating activation of ascorbate-glutathione cycle.",
Arsenic,2337185,"Assessment of metal pollution associated with an alteration area: Old Gümü?hane, NE Black Sea Abstract: The objective of this study was to determine the potential environmental risks associated with the Kirkpavli (Old Gümü?hane in northern Turkey) alteration area by quantifying pollution in soil. The Kirkpavli (Old Gümü?hane) alteration area is situated at the south of the deposit with the same name of gold-silver-bearing lead, zinc, and copper in the southern part of the Black Sea Tectonic Unit (Eastern Pontides). In this study, 28 soil samples acquired from the alteration area were analyzed for contents of some main elements including lead (Pb), copper (Cu), zinc (Zn), cadmium (Cd), cobalt (Co), manganese (Mn), nickel (Ni), and arsenic (As). Contents of the elements in the area were determined, and high values were obtained such as 1,171 mg/kg for As, 12.4 mg/kg for Cd, 77.3 mg/kg for Co, 341 mg/kg for Cu, 1,172 mg/kg for Mn, 51.9 mg/kg for Ni, 3,725 mg/kg for Pb, and 880 mg/kg for Zn. Soil contamination was appraised on the basis of Geoaccumulation Index (I geo), Enrichment Factor (EF), Pollution Index, and Integrated Pollution Index. The calculated results of I geo, EF, and PI of the elements can be shown in descending order of parameters as As?&gt;?Pb?&gt;?Cd?&gt;?Zn?&gt;?Cu?&gt;?Co?&gt;?Mn. The parameters for some of these elements indicated extremely high contamination (I geo?&gt;?5), extremely high enrichment (EF?&gt;?40), and high pollution (PI?&gt;?3). High I geo, EF, and PI values of As, Pb, and Cd in the soil samples mean that soil pollution is typically associated with alteration area. Considering its location and the results of this study, the Kirkpavli alteration area is a significant source of pollution and may have ecotoxicological effects on terrestrial, groundwater, and aquatic ecosystems in the region.",
Arsenic,1255660,"Environmental exposure to arsenic may reduce human semen quality: Associations derived from a Chinese cross-sectional study Abstract: ABSTRACT: BACKGROUND: Recent observations in in vitro and in vivo models suggest that arsenic (As) is an endocrine disruptor at environmentally-relevant levels. When exposed to As, male rats and mice show steroidogenic dysfunction that can lead to infertility. However, the possible effects of As on human male semen quality remain obscure. METHODS: We monitored the profile of As species in the urine of a reproductive-age human cohort and assessed its association with semen quality. Men (n = 96) were recruited in an infertility clinic from July 2009 to August 2010 in the Affiliated Hospital of Chongqing Institute for Population and Family Planning. Five urinary As species were analyzed by high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Clinical information on the semen volume, sperm concentration and motility was employed to catalogue and evaluate semen quality according to WHO guidelines. As species concentrations in addition to other continuous variables were dichotomized by the medians and modelled as categorical variables in order to explore using the binary logistic regression possible associations between As exposure and semen quality. RESULTS: Urinary concentrations (geometric mean +/- SD, mug g-1 creatinine) of different As species were 7.49 (+/-24.8) for AsB, 20.9 (+/-13.7) for DMA, 2.77 (+/-3.33) for MMA, and 4.03 (+/-3.67) for Asi (AsiIII and AsiV). DMA concentrations above the median were significantly associated with below-reference sperm concentrations (P =0.02) after adjusting for age, body mass index (BMI), abstinence, smoking and drinking habits. In addition, smoking was positively associated with MMA. CONCLUSION: Reduced parameters in human semen quality are positively associated with As exposure in a reproductive-age Chinese cohort.",
Arsenic,627754,"Monomethylarsonous acid induces transformation of human bladder cells Abstract: Arsenic is a human bladder carcinogen. Arsenic is methylated to both monomethyl and dimethyl metabolites which have been detected in human urine. The trivalent methylated arsenicals are more toxic than inorganic arsenic. It is unknown if these trivalent methylated metabolites can directly cause malignant transformation in human cells. The goal of this study is determine if monomethylarsonous acid (MMA(III)) can induce malignant transformation in a human bladder urothelial cell line. To address this goal, a non-tumorigenic human urothelial cell line (UROtsa) was continuously exposed to 0.05 muM MMA(III) for 52 weeks. Hyperproliferation was the first phenotypic change observed in exposed UROtsa (URO-MSC). After 12 weeks of exposure, doubling time had decreased from 42 h in unexposed control cells to 27 h in URO-MSC. Hyperproliferation continued to be a quality possessed by the URO-MSC cells after both 24 and 52 weeks of exposure to MMA(III), which had a 40-50% reduction in doubling time. Throughout the 52-week exposure, URO-MSC cells retained an epithelial morphology with subtle morphological differences from control cells. 24 weeks of MMA(III) exposure was required to induce anchorage-independent growth as detected by colony formation in soft agar, a characteristic not found in UROtsa cells. To further substantiate that malignant transformation had occurred, URO-MSC cells were tested after 24 and 52 weeks of exposure to MMA(III) for the ability to form tumors in SCID mice. Enhanced tumorigenicity in SCID mouse xenografts was observed after 52 weeks of treatment with MMA(III). These observations are the first demonstration of MMA(III)-induced malignant transformation in a human bladder urothelial cell line and provide important evidence that MMA(III) may be carcinogenic in human tissues.",
Arsenic,1016414,"Corrigendum to ""Chronic low-level arsenic exposure causes gender-specific alterations in locomotor activity, dopaminergic systems, and thioredoxin expression in mice"" [Toxicology and Applied Pharmacology (2009) 169-177] Abstract: Arsenic (As) is a toxic metalloid widely present in the environment. Human exposure to As has been associated with the development of skin and internal organ cancers and cardiovascular disorders, among other diseases. A few studies report decreases in intelligence quotient (IQ), and sensory and motor alterations after chronic As exposure in humans. On the other hand, studies of rodents exposed to high doses of As have found alterations in locomotor activity, brain neurochemistry, behavioral tasks, and oxidative stress. In the present study both male and female C57Bl/6J mice were exposed to environmentally relevant doses of As such as 0.05, 0.5, 5.0, or 50 mg As/L of drinking water for 4 months, and locomotor activity was assessed every month. Male mice presented hyperactivity in the group exposed to 0.5 mg As/L and hypoactivity in the group exposed to 50 mg As/L after 4 months of As exposure, whereas female mice exposed to 0.05, 0.5, and 5.0 mg As/L exhibited hyperactivity in every monthly test during As exposure. Furthermore, striatal and hypothalamic dopamine content was decreased only in female mice. Also decreases in tyrosine hydroxylase (TH) and cytosolic thioredoxin (Trx-1) mRNA expression in striatum and nucleus accumbens were observed in male and female mice, respectively. These results indicate that chronic As exposure leads to gender-dependent alterations in dopaminergic markers and spontaneous locomotor activity, and down-regulation of the antioxidant capacity of the brain.",
Arsenic,1350434,"Involvement of arachidonic acid in chemical stress-induced interleukin-6 synthesis in osteoblast-like cells: comparison with heat shock protein 27 induction Abstract: In a previous study, we have demonstrated that sodium arsenite (arsenite) as chemical stress stimulates heat shock protein 27 (HSP27) induction and arachidonic acid release in osteoblast-like MC3T3-E1 cells, and that the response of HSP27 induction is coupled with metabolic activity of the arachidonic acid cascade. In the present study, we examined the effect of exposure to arsenite on the synthesis of interleukin-6 (IL-6) in these cells. Arsenite induced the synthesis of IL-6 after 6 h from the stimulation up to 48 h. The effect of arsenite on IL-6 synthesis was dose-dependent in the range between 10 and 500 microM. The arsenite-induced IL-6 synthesis was enhanced by the pretreatment with indomethacin, an inhibitor of cyclooxygenase. Nordihydroguaiaretic acid, a lipoxygenase inhibitor, significantly amplified the arsenite-induced IL-6 synthesis. Melittin, an activator of phospholipase A2, which by itself hardly affected the levels of IL-6, markedly enhanced the arsenite-induced IL-6 synthesis. These results strongly suggest that chemical stress induces IL-6 synthesis in osteoblasts, and that the IL-6 synthesis is coupled to the arachidonic acid cascade as well as the HSP27 induction by arsenite.",
Arsenic,627024,"Sodium arsenite impairs insulin secretion and transcription in pancreatic ?-cells Abstract: Human studies have shown that chronic inorganic arsenic (iAs) exposure is associated with a high prevalence and incidence of type 2 diabetes. However, the mechanism(s) underlying this effect are not well understood, and practically, there is no information available on the effects of arsenic on pancreatic ?-cells functions. Thus, since insulin secreted by the pancreas plays a crucial role in maintaining glucose homeostasis, our aim was to determine if sodium arsenite impairs insulin secretion and mRNA expression in single adult rat pancreatic ?-cells. Cells were treated with 0.5, 1, 2, 5 and 10 ?M sodium arsenite and incubated for 72 and 144 h. The highest dose tested (10 ?M) decreased ?-cell viability, by 33% and 83%, respectively. Insulin secretion and mRNA expression were evaluated in the presence of 1 and 5 ?M sodium arsenite. Basal insulin secretion, in 5.6 mM glucose, was not significantly affected by 1 or 5 ?M treatment for 72 h, but basal secretion was reduced when cells were exposed to 5 ?M sodium arsenite for 144 h. On the other hand, insulin secretion in response to 15.6 mM glucose decreased with sodium arsenite in a dose-dependent manner in such a way that cells were no longer able to distinguish between different glucose concentrations. We also showed a significant decrease in insulin mRNA expression of cells exposed to 5 ?M sodium arsenite during 72 h. Our data suggest that arsenic may contribute to the development of diabetes mellitus by impairing pancreatic ?-cell functions, particularly insulin synthesis and secretion.",
Arsenic,2345812,"Effect of citric acid and rhizosphere bacteria on metal plaque formation and metal accumulation in reeds in synthetic acid mine drainage solution Abstract: Many of regions in the world have been affected by acid mine drainage (AMD). The study assessed the effect of rhizosphere bacteria and citric acid (CA) on the metal plaque formation and heavy metal uptake in Phragmites australis cultured in synthetic AMD solution. Mn and Al plaque were not formed, but Fe plaque which was mediated by rhizosphere iron oxidizing bacteria (Fe(II)OB) was observed on the root system of reeds. Fe plaque did not significantly influence the uptake of Fe, Al and Mn into tissues of reeds. CA significantly (p &lt; 0.01) inhibited the growth of Fe(II)OB and decreased the formation of Fe plaque. CA also significantly improved (p &lt; 0.05) the accumulation of Fe, Mn and Al in all the tissues of reeds. Roots and rhizomes were the main organs to store metals. The roots contained 0.08 +/- 0.01 mg/g Mn, 2.39 +/- 0.26 mg/g Fe and 0.19 +/- 0.02 mg/g Al, while the shoots accumulated 0.04 +/- 0.00 mg/g Mn, 0.20 +/- 0.01 mg/g Fe, 0.11 +/- 0.00 mg/g Al in reeds cultured in solution amended with 2.101 g/I CA and without inoculation of rhizosphere bacteria. (C) 2014 Elsevier Inc. All rights reserved.",
Arsenic,1579341,"Regulation of cellular Cyclin D1 gene by arsenic is mediated through miR-2909 Abstract: Arsenic through its ability to regulate genes that link cell cycle control with apoptosis has been widely recognized to play a crucial role in oncogenomics. However, the molecular event by which arsenic affects such genes is far from clear. Here we provide reasonably good evidence to support the view that arsenic exposure to human PBMCs (peripheral blood mononuclear cells) at low concentrations results in the over-expression of miR-2909 within these cells. This over-expressed miR-2909 was found to regulate CCND1 (Cyclin D1) gene expression, within these cells by inducing splice-switching of tumor suppresser CYLD (Cylindromatosis) gene as well as modulation of SP1 (Specificity Protein 1) activity through the repression of KLF4 (Kruppel-like factor4) expression at the translational level. Arsenic dependent regulation of AATF (Apoptosis Antagonizing Transcription factor) and BCL3 (B-cell Lymphoma 3) were also found to be modulated through its capacity to induce miR-2909 expression. Based upon these observations, a novel epigenomic pathway was proposed which may not only be useful in understanding the paradoxical role of arsenic in oncogenomics but also may even be useful in devising various strategies for the treatment/prevention of tumors induced by arsenic.",
Arsenic,1579395,"Ars2 is overexpressed in human cholangiocarcinomas and its depletion increases PTEN and PDCD4 by decreasing microRNA-21 Abstract: Due to the lack of effective diagnostic tools, most patients with cholangiocarcinoma (CCA) have no chance of surgical resection. Ars2 is a protein that was reported to be important for microRNA (miR) biogenesis, and its depletion can reduce the levels of several miRs, including miR-21, which is overexpressed in CCAs. We hypothesized that Ars2 was also present in CCAs and could be an early diagnostic marker. In our experiments, Ars2, PTEN, PDCD4, and miR-21 were evaluated in 18 CCAs and paired normal tissues. ShArs2, miR-21 mimics, and Ars2 were transfected into CCA and bile duct epithelial cells either alone or together. Cell proliferation, tumorigenicity analysis and expression changes of Ars2, PTEN, PDCD4, and miR-21 were evaluated. We found that both Ars2 and miR-21 were overexpressed, with 95% sensitivity and 100% specificity, and an ROC of 0.995 in distinguishing between CCAs and paired normal tissues by qRT-PCR. PTEN and PDCD4 were reversed in immunohistochemistry, but no difference was observed using qRT-PCR. The knockdown of Ars2 in CCA cells decreased the level of miR-21, inhibited cell proliferation and prevented tumor formation in nude mice. Ars2 knockdown also led to an increase in both PTEN and PDCD4 protein levels. Both proteins decreased when the miR-21 mimic was con-transfected. However, the overexpression of Ars2 alone could not get the opposite results. Based on our data, we conclude that Ars2 is overexpressed in human CCA and may be a diagnostic marker. Ars2 depletion increases PTEN and PDCD4 protein levels via the reduction of miR-21.",
Arsenic,1034001,"Arsenic and respiratory cancer in humans: Follow-up of copper smelter employees in Montana Abstract: As a follow-up to an earlier study concerned with the role of arsenic in human carcinogenesis, the mortality experience during 1938-77 of 8,045 white male smelter employees in Montana exposed to arsenic trioxide was compared to that of the white male population of the same region. The excess mortality among smelter employees was due largely to respiratory cancer and diseases of the heart. Respiratory cancer mortality was analyzed with reference to period of first employment, length of employment, and degree of exposure to arsenic trioxide and sulfur dioxide. The excess in respiratory cancer was seven to eight times that expected among men first employed prior to 1925 who were heavily or moderately exposed to arsenic trioxide; it was more than four times that expected among men heavily exposed and first employed in 1925-47, and it decreased in direct proportion to degree of arsenic trioxide exposure. Inhaled arsenic trioxide was strongly implicated as the primary agent associated with the excess respiratory cancer, with sulfur dioxide perhaps enhancing the effect.",
Arsenic,1021850,"Potentiation of vasoconstriction and pressor response by low concentration of monomethylarsonous acid (MMA(III)) Abstract: A close link between arsenic exposure and hypertension has been well-established through many epidemiological reports, yet the mechanism underlying it remains unclear. Here we report that nanomolar concentrations of monomethylarsonous acid (MMA(III)), a toxic trivalent methylated arsenic metabolite, can potentiate agonist-induced vasoconstriction and pressor responses. In freshly isolated rat aortic ring, exposure to nanomolar MMA(III) (100-500 nM) potentiated phenylephrine (PE)-induced vasoconstriction while at higher concentrations (?2.5 ?M), suppression of vasoconstriction and apoptosis of vascular smooth muscle were observed. Potentiation of agonist-induced vasoconstriction was also observed with other contractile agonists and it was retained in endothelium-denuded aortic rings, suggesting that these events are agonist-independent and smooth muscle cell dependent. Interestingly, exposure to MMA(III) resulted in increased myosin light chain phosphorylation while PE-induced Ca2+ influx was not affected, reflecting that Ca2+ sensitization is involved. In line with this, MMA(III) enhanced agonist-induced activation of small GTPase RhoA, a key contributor to Ca2+ sensitization. Of note, treatment of MMA(III) to rats induced significantly higher pressor responses in vivo, demonstrating that this event can occur in vivo indeed. We believe that RhoA-mediated Ca2+ sensitization and the resultant potentiation of vasoconstriction by MMA(III) may shed light on arsenic-associated hypertension.",
Arsenic,1025263,"Arjunolic acid attenuates arsenic-induced nephrotoxicity Abstract: Arsenic is highly toxic naturally occurring element that affects numerous organ systems in humans. Present study was designed to investigate the preventive role of a triterpenoid saponin, arjunolic acid (AA) against arsenic-induced nephrotoxicity in mouse model. For this study, NaAsO(2) was chosen as the source of arsenic. Oral administration of NaAsO(2) at a dose of 10mg/kg body weight for 2 days caused significant accumulation of arsenic in renal tissues as well as altered the activities of serum markers, urea nitrogen (UN) and creatinine, antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx), level of cellular metabolites, reduced glutathione (GSH), oxidized glutathione (GSSG) and total thiols, level of lipid peroxidation end products and protein carbonyl content. Treatment with AA at a dose of 20mg/kg body weight for 4 days almost normalized above indices. Histological studies also indicated preventive role of AA against NaAsO(2)-induced nephrotoxicity. The radical scavenging activity and in vivo antioxidant power of AA were determined from its DPPH radical scavenging ability and ferric reducing/antioxidant power (FRAP), respectively. A well-known antioxidant, vitamin C was used as positive control throughout the study. Combining all, results suggest that arsenic could cause kidney damage by inducing oxidative stress in mice and that could be prevented by AA.",
Arsenic,1028788,"A retrospective mortality study of workers exposed to arsenic in a gold mine and refinery in France Abstract: A historical mortality study of a cohort of employees of a gold mining and refining company was carried out in Salsigne, France. A major goal of the study was to investigate the relationship between lung cancer mortality and exposure to arsenic, radon, silica, and other contaminants of the working environment. A twofold excess of lung cancer was found both among miners and smelters, mainly concentrated among workers who had experienced exposure to past levels of arsenic, radon, and silica. The consistency of the results in the mine and the refinery are suggestive of a carcinogenic risk from both soluble and insoluble arsenic, although the potential role of other factors cannot be dismissed.",
Arsenic,1337781,"Characterization and transcription of arsenic respiration and resistance genes during in situ uranium bioremediation Abstract: The possibility of arsenic release and the potential role of Geobacter in arsenic biogeochemistry during in situ uranium bioremediation was investigated because increased availability of organic matter has been associated with substantial releases of arsenic in other subsurface environments. In a field experiment conducted at the Rifle, CO study site, groundwater arsenic concentrations increased when acetate was added. The number of transcripts from arrA, which codes for the ?-subunit of dissimilatory As(V) reductase, and acr3, which codes for the arsenic pump protein Acr3, were determined with quantitative reverse transcription-PCR. Most of the arrA (&gt;60%) and acr3-1 (&gt;90%) sequences that were recovered were most similar to Geobacter species, while the majority of acr3-2 (&gt;50%) sequences were most closely related to Rhodoferax ferrireducens. Analysis of transcript abundance demonstrated that transcription of acr3-1 by the subsurface Geobacter community was correlated with arsenic concentrations in the groundwater. In contrast, Geobacter arrA transcript numbers lagged behind the major arsenic release and remained high even after arsenic concentrations declined. This suggested that factors other than As(V) availability regulated the transcription of arrA in situ, even though the presence of As(V) increased the transcription of arrA in cultures of Geobacter lovleyi, which was capable of As(V) reduction. These results demonstrate that subsurface Geobacter species can tightly regulate their physiological response to changes in groundwater arsenic concentrations. The transcriptomic approach developed here should be useful for the study of a diversity of other environments in which Geobacter species are considered to have an important influence on arsenic biogeochemistry.",
Arsenic,1031631,"Effect of arsenite on renal tissue slice metabolism in chronic metabolic acidosis and alkalosis Abstract: Tissue slices prepared from renal cortex of littermate dogs with chronic metabolic acidosis or alkalosis were incubated in media with or without arsenite and containing 1 mM L-[14C]glutamine or [1,5-14C]citrate. The presence of arsenite increased the concentration of alpha-ketoglutarate in slices by 5--20 times the values found without this inhibitor. alpha-Ketoglutarate concentrations in acidotic slices were 40% or more greater than those in alkalotic ones when arsenited was present. 14C incorporation into alpha-ketoglutarate was also increased manyfold by arsenite with either labeled glutamine or citrate as substrate. 14CO2 production from labeled glutamine by over 90% and from labeled citrate by over 75%; the difference between 14CO2 production by acidotic and alkalotic slices was greatly reduced or eliminated by arsenite. These results suggest that in chronic metabolic acidosis metabolism of both glutamine and citrate is stimulated at a site or sites preceding formation of alpha-ketoglutarate.",
Arsenic,1256738,"Anthropogenic and geogenic impacts on arsenic bioaccessibility in UK topsoils Abstract: Predictive linear regression (LR) modelling between bioaccessible arsenic (B-As) and a range of total elemental compositions and soil properties was executed in order to assess the potential for developing a national B-As dataset for the UK. LR indicates that total arsenic (As) is the only highly significant independent variable for estimating B-As in urban areas where it explains 75-92% of the variance. The broad compatibility of the London, Glasgow and Swansea regression models suggests that application of these models to estimate bioaccessible As in UK soils impacted by diffuse anthropogenic urban contamination and non-ferrous metal processing should be relatively accurate. In areas dominated by Jurassic ironstones and associated clays and limestones, total As, P and pH are significant, accounting for 53, 14 and 5%, respectively, of the B-As variance. Models based on total As as the sole predictor in the combined Jurassic and Cretaceous sedimentary ironstones datasets explain about 40% of the B-As variance. The median As bioaccessible fraction (%As-BAF) is 19 to 28% in the anthropogenic contamination impacted urban domains, but much lower (5-9%) in geogenic terrains dominated by ironstones. Results of this study can be used as part of a lines of evidence approach to localised risk assessment but should not be used to replace bioaccessibility testing at individual sites where local conditions may vary considerably from the broad overview presented in this study.",
Arsenic,1378290,"Trivalent methylated arsenicals induce procoagulant activity through phosphatidylserine exposure in human platelets Abstract: Arsenic, an important environmental pollutant, is reported to be associated with carcinogenicity and cardiovascular disease. Monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), the metabolites of inorganic arsenic, are recently known to be responsible for the toxicity of environmental arsenic. To study the role of these metabolites in arsenic-induced cardiovascular diseases, we investigated the effects of trivalent methylated arsenicals on procoagulant activity of human platelets, which is essential in blood clotting, thrombus formation and progression of cardiovascular diseases. MMAIII significantly induced exposure of phosphatidylserine (PS) to outer membrane, an important mediator of procoagulant activity of platelets, in a time- and concentration-dependent manner. MMAIII-induced PS exposure appeared to be from the inhibition of flippase activity, mediated by depletion of intracellular ATP and protein thiol. Increase of intracellular calcium and activation of scramblase were not observed, suggesting these events were not associated with MMAIII-induced PS exposure. Consistent with PS exposure, MMAIII increased thrombin generation as measured by prothrombinase complex assay, confirming MMAIII can induce procoagulant activity of platelets. Another important trivalent methylated arsenical, DMAIII induced platelet procoagulant activity more potently. DMAIII induced flippase inhibition and cellular ATP depletion similar to MMAIII, but interestingly depletion of protein thiol was not observed. In conclusion, MMAIII and DMAIII induced procoagulant activity of platelets through PS exposure. These increased platelet procoagulant activities might be a major contributing factor in cardiovascular diseases associated with chronic exposure of arsenic by drinking water.",
Arsenic,628462,"Urogenital carcinogenesis in female CD1 mice induced by in utero arsenic exposure is exacerbated by postnatal diethylstilbestrol treatment Abstract: Transplacental inorganic arsenic carcinogenicity, together with postnatal exposure to diethylstilbestrol or tamoxifen, was studied. Pregnant CD1 mice received 85 ppm arsenic in the drinking water from gestation days 8 to 18 and were allowed to give birth. Groups (n = 35) of female offspring were injected s.c. on postpartum days 1 through 5 with diethylstilbestrol (2 microg/pup/d) or tamoxifen (10 microg/pup/d) and observed for 90 weeks. Arsenic alone induced some urogenital system tumors, including mostly benign tumors of the ovary and uterus, and adrenal adenoma. Diethylstilbestrol alone induced some tumors (primarily cervical) but when given after in utero arsenic, it greatly enhanced urogenital tumor incidence, multiplicity, and progression. For instance, compared with the incidence of urogenital malignancies in the control (0%), arsenic alone (9%), and diethylstilbestrol alone (21%) groups, arsenic plus diethylstilbestrol acted synergistically, inducing a 48% incidence of malignant urogenital tumors. Of the urogenital tumors induced by arsenic plus diethylstilbestrol, 80% were malignant, and 55% were multiple site. Arsenic plus diethylstilbestrol increased ovarian, uterine, and vaginal tumors, and urinary bladder proliferative lesions, including three transitional cell carcinomas. Tamoxifen alone did not increase urogenital tumors or affect arsenic-induced neoplasia but did increase arsenic-induced uroepithelial proliferative lesions. Uterine and bladder carcinoma induced by arsenic plus diethylstilbestrol greatly overexpressed estrogen receptor-alpha (ER-alpha) and pS2, an estrogen-regulated gene. In neonatal uteri, prenatal arsenic increased ER-alpha expression and enhanced estrogen-related gene expression induced by postnatal diethylstilbestrol. Thus, arsenic acts with estrogens to enhance production of female mouse urogenital cancers.",
Arsenic,1356817,"Arsenic iduced growth arrest and apoptosis in mouse B cell lines Abstract: Human exposure to arsenic in drinking water affects millions of people worldwide and has been associated with neoplasias in multiple organs and has also been demonstrated to have immunotoxic effects. The exact molecular mechanism of carcinogenesis has not been defined. Of particular note is the modulation of MAP kinase activities resulting in the activation of NF-kB and c-Myc transcription factors in neoplastic cells. These pathways are also of particular importance in the development and regulation of inflammation, however, the effect of arsenic on these pathways has not been fully evaluated in lymphocyte populations. A link between inflammation and carcinogenesis has been established in several epidemiological studies as well as in mouse models, and B-lymphocytes have recently been shown to be critical in the initiation of inflammation-induced carcinogenesis. We, therefore, initiated a study to examine mechanisms underlying the immunotoxicity of arsenite in an in vitro model system of mouse B lymphocytes. Three B cell lines (70Z/3, WEHI-231, and 2PK-3) and one macrophage line (RAW 247.3) were exposed with 0-50 microM of Arsenite and effects on cell growth, cell division, cell cycle, and apoptosis were examined. All three B cell lines showed at least a 5-fold greater sensitivity to arsenite exposure than the macrophage cell line, indicated by growth inhibition and cell cycle arrest. The B cell lines were also were observed to have an increase in apoptosis at lower concentrations than the macrophage cell line. A clear reduction in cell division and growth was observed at 5 microM and cell cycle analysis identified a reduction in cells entering S and G2/M as well as an increase in apoptotic cells. These results indicate an increased sensitivity of B cells to Arsenic and future determination of arsenic induced cellular signaling in mouse B cell lines will provide a clearer understanding of arsenic induced inflammatory mechanisms and its role in the promotion of arsenic induced carcinogensis.",
Arsenic,628451,"Induction of tumors of the liver, lung, ovary and adrenal in adult mice after brief maternal gestational exposure to inorganic arsenic: Promotional effects of postnatal phorbol ester exposure on hepatic and pulmonary, but not dermal cancers Abstract: Arsenic is a recognized human carcinogen and development of rodent models remains a critically important research objective. Since gestation can be a period of high sensitivity to chemical carcinogenesis, we have performed a series of transplacental carcinogenicity studies in mice with inorganic arsenic. In this study, groups of pregnant C3H mice received drinking water containing sodium arsenite (NaAsO2) at 0, 42.5 and 85 p.p.m. arsenic ad libitum from days 8 to 18 of gestation. These doses of arsenic were well tolerated. Dams delivered normally and at weaning (4 weeks) offspring were randomly put into groups (n = 25) of males or females according to maternal dose. In an attempt to promote skin cancers initiated by transplacental arsenic, duplicate groups of control or arsenic exposed offspring were topically exposed to 12-O-tetradecanoyl phorbol-13-acetate (TPA; 2 micro g/0.1 ml acetone, twice/week) from 4 to 25 weeks of age. Irrespective of TPA exposure, male offspring showed arsenic-induced dose-related increases in hepatocellular carcinoma incidence and multiplicity, as well as increases in adrenal tumor incidence and multiplicity. In female offspring, an increase in epithelial ovarian tumors occurred with arsenic exposure regardless of TPA exposure. Females also showed pre-neoplastic lesions of the reproductive tract, including hyperplasia of the uterus and oviduct, after arsenic but independent of TPA exposure. Although TPA had no effect on skin tumors, it promoted arsenic initiated liver tumors in females and lung tumors in both sexes. Thus, inorganic arsenic, as a single agent, can consistently act as a complete transplacental carcinogen in mice, inducing tumors at multiple sites, and as a tumor initiator in some tissues. Skin tumors were not initiated by arsenic in mouse fetuses possibly indicating tissue-specific mechanisms of action. This study indicates that gestation is a period of high sensitivity to arsenic carcinogenesis.",
Arsenic,1372367,"Differential effects of pretreatment and posttreatment of sodium arsenite on the genotoxicity of methyl methanesulfonate in Chinese hamster ovary cells Abstract: BIOSIS COPYRIGHT: BIOL ABS. Pretreatment of sodium arsenite reduces hypoxanthine-guanine phosphoribosyltransferase mutagenicity and overcomes the inhibition of mitosis and cell proliferation but has no apparent effect on the cytotoxicity and clastogenicity in methyl methanesulfonate (MMS)-treated Chinese hamster ovary cells. Posttreatment of sodium arsenite drastically increases the cytotoxicity, clastogenicity, hypoxanthine-guanine phosphoribosyltransferase mutagenicity, and inhibition of mitosis and cell proliferation induced by MMS. Sodium arsensite either pre- or posttreatment has no apparent effect on the MMS-induced sister chromatid exchanges. The present results indicate that pretreatment of sodium arsenite not only does no harm but may even benefit the MMS-treated cells. On the contrary, posttreatment of sodium arsenite is cogenotoxic.",
Arsenic,2149333,"Preliminary Investigation into Occurrence and Removal of Arsenic, Cadmium, Mercury, and Zinc in Wastewater Treatment Plants in Cape Town and Stellenbosch Abstract: ",
Arsenic,905067,"Investigating childhood leukemia in Churchill County, Nevada Abstract: Sixteen children diagnosed with acute leukemia between 1997 and 2002 lived in Churchill County, Nevada, at the time of or before their illness. Considering the county population and statewide cancer rate, fewer than two cases would be expected.<br /><br /> In March 2001, the Centers for Disease Control and Prevention led federal, state, and local agencies in a cross-sectional, case-comparison study to determine if ongoing environmental exposures posed a health risk to residents and to compare levels of contaminants in environmental and biologic samples collected from participating families.<br /><br /> Surveys with more than 500 variables were administered to 205 people in 69 families. Blood, urine, and cheek cell samples were collected and analyzed for 139 chemicals, eight viral markers, and several genetic polymorphisms. Air, water, soil, and dust samples were collected from almost 80 homes to measure more than 200 chemicals.<br /><br /> The scope of this cancer cluster investigation exceeded any previous study of pediatric leukemia. Nonetheless, no exposure consistent with leukemia risk was identified. Overall, tungsten and arsenic levels in urine and water samples were significantly higher than national comparison values; however, levels were similar among case and comparison groups.<br /><br /> Although the cases in this cancer cluster may in fact have a common etiology, their small number and the length of time between diagnosis and our exposure assessment lessen the ability to find an association between leukemia and environmental exposures. Given the limitations of individual cancer cluster investigations, it may prove more efficient to pool laboratory and questionnaire data from similar leukemia clusters.",
Arsenic,1255530,"Origin, mobility, and temporal evolution of arsenic from a low-contamination catchment in Alpine crystalline rocks Abstract: The reduction to 10?g/l of the limit for arsenic in drinking water led many resource managers to deal with expensive treatments. In the very common case of arsenic levels close to the recommended maximum concentration, knowing the origin and temporal evolution of As has become of great importance. Here we present a case study from an alpine basin. Arsenic speciation, isotopic compositions of pyrite, sulfate and water, and concentrations of major and trace elements demonstrate a geogenic source for arsenic linked to the dissolution of pyrite. We provide new tools to further study As at low concentrations where many processes may be masked. The observed negative correlation between ?(34)S(SO4) and [As] is interpreted as a Rayleigh-type sulfur-isotope fractionation during increasing pyrite dissolution. The observed positive correlation between ?(18)O(SO4) and As(V)/As(III) could help to retrieve initial redox conditions. A 3-year long monitoring at high-resolution demonstrated that drought conditions enhance pyrite dissolution whose degradation products are scavenged by recharge water. An increase in As in groundwater may result from droughts due to enhanced oxygen entry in the unsaturated zone. The 2003 European heatwave had a major effect.",
Arsenic,1020683,"Dust mites living in human lungs--the cause of asthma? Abstract: Asthma does not have a clear cause and may represent a cluster of diseases. We propose that asthma in house dust mite sensitive patients may be caused by recurrent inhalation of live dust mites which are able to live for some time in the bronchioles of the lung. To provide themselves with a food source, the mites may purposefully excrete proteolytic enzymes, including Der p1, which increase epithelial shedding by freeing cells from the basement membrane. The mites then feed on the shed respiratory epithelial cells. Consequent loss of an intact respiratory epithelium exposes underlying tissues to dust mite protein and other allergens triggering sensitisation to these proteins. Later, repeated infestation provokes an allergic response which manifests itself as asthma attacks. The evidence for this hypothesis was tested against the Bradford-Hill criteria for causation; consistency, strength, temporal association and dose response. Potential areas for further research were also identified. The association between asthmatic symptoms and pulmonary acariasis was consistent across a number of studies. Determining the strength of the association and any dose response requires more work which is dependent on the development of better tests for the detection of mites in sputum. There was tentative evidence of a temporal association in the published studies identified. Biological plausibility and experimental evidence was available for pulmonary acariasis in primates and arsenic treatment was effective in humans. Better tests for mites in sputum are needed, as is work to assess more modern anti-acaricidal drugs in dust mite sensitive asthmatics.",
Arsenic,710974,"Learning deficits in C57BL/6J mice following perinatal arsenic exposure: Consequence of lower corticosterone receptor levels Abstract: Most studies on arsenic as a drinking water contaminant have focused on its carcinogenic potential but a few suggest that arsenic can adversely affect cognitive development. One parameter of the hypothalamic-pituitary-adrenal axis, the corticosterone receptor (CR) has been shown to be altered by arsenic. These receptors are found throughout the central nervous system, particularly in the hippocampus, an area of the brain of central importance for learning and memory. We examined the impact of perinatal exposure to 50 parts per billion (ppb) sodium arsenate on CRs and learning and memory behavior in the C57BL/6J mouse. Measurements of CRs revealed that arsenic-exposed offspring have significantly lower levels of these receptors in the nucleus than controls. Exposed offspring showed longer latency to approach a novel object than controls in an object recognition task. In the 8-way radial arm maze, arsenic offspring had a significant increase in the number of entry errors compared to controls. Results suggest that moderate exposures to perinatal arsenic can significantly reduce CR levels in the hippocampus and can have adverse effects on learning and memory behavior.",
Arsenic,1255497,"Accumulation and toxic effect of arsenic and other heavy metals in a contaminated area of West Bengal, India, in the lichen Pyxine cocoes (Sw.) Nyl Abstract: Ecological indicators can be used to assess the condition of the environment, to provide an early warning signal of changes in the surrounding environment or to diagnose the causes of an environmental problem. Ecological indicators can be used to assess the condition of the environment, to provide an early warning signal of changes in the surrounding environment or to diagnose the causes of an environmental problem. The study aims to evaluate the applicability of a common foliose lichen Pyxine cocoes (Sw.) Nyl., as an indicator to evaluate the arsenic and heavy metal rich sites. The naturally growing lichen and its substratum (bark) were utilized to biomonitor the accumulation of arsenic (As) and other heavy metals (Al, Cd, Cr, Cu, Fe, Pb and Zn) in Chinsurah, a highly As contaminated area of West Bengal. Significantly higher levels of Al, Cr, Fe, Pb and Zn (p<0.01), Cd and Cu (p<0.05) were found in the lichens especially in samples collected from road sites. Higher As concentration (48.1±2.1 ?g g?1) in samples were found near the paddy field, indicating pesticide-herbicides as its source used in agriculture. The substrate exhibits lower concentration of most of the metals while Cr, Cd and Pb were below detection limit. As evident from the bioaccumulation factor most of the metals accumulated in lichen thallus are air borne. Chl a and Chl b concentrations decreased significantly with increasing distance from roadside whereas the carotenoid and protein showed an enhanced level. The chlorophyll stability index, chlorophyll degradation and carotenoid contents were found to be the most sensitive parameters to assess the vitality of lichen thallus against changing environment.",
Arsenic,1378417,"Effect Of Subchronic Arsenite Exposure On Sensory Sural Nerves Of Rats Abstract: Inorganic arsenic (iAs) is considered a neurotoxic. In humans, this metalloid induced a notorious deficit in attention, memory and learning abilities as well as peripheral neuropathies. Such effects have been mainly associated to the presence of arsenic in cerebral tissue. In this study we analyzed the presence of iAs and its metabolites, the electrophysiological and histological characteristics, and the oxidative damage [thiobarbituric acid-reactive substances (TBARS) concentration] in peripheral sural nerves from control and iAs-exposed rats. Wistar male rats (230 g bw) received sodium arsenite (10 mg/kg bw/day, gavage, for 30 days. On completion of experimental period, rats were sacrificed by cervical dislocation. The sural nerves from both hind limbs were carefully dissected out, washed, and divided into three segments. One segment was immediately homogenized in ice-cold phosphate buffer pH 7.4 for TBARS analysis and for arsenic species analysis. Second segment was prepared for compound action potential (CAP) response, evoked by single electrical pulses and the last segment for histological examination. The results show that dimethylarsenic (DMAs) was the most ubiquitous iAs metabolite in nerves of exposed animals (~95%). TBARS concentration in sural nerves was significantly increased in arsenite exposed group relative to control group (p<0.0001). In addition, a positive relationship was found between TBARS and DMAs content in nerve (r2=0.9772; n=16; p<0.0001). Meanwhile, the CAP evoked in exposed nerves showed a reduction in area (~35%; p=0.094), in velocity of conduction (~26%; p<0.05), and reduction in axonal myelin sheath thickness (~56%; p<0.001), than nerves from control rats. Our results suggest that the extent concentration of DMAs induced the oxidative damage in sural nerve, affecting the normal transmission of sensory information from periphery to the central nervous system.",
Arsenic,1519005,"Molecular modifications induced by inorganic arsenic in Vicia faba investigated by FTIR, FTNIR spectroscopy and genotoxicity testing Abstract: Exposure to inorganic arsenic (iAs) through drinking water is a major public health concern affecting most countries. Epidemiologic studies showed a significant association between consumption of iAs through drinking water and different types of cancer. However, the exact mechanisms underlying As-induced cancer and other diseases are not yet well understood. The aim of this study is to determine the effects of exposure iAs (20 or 30 mg/L) on Vicia faba seedlings in terms of phytotoxicity, genotoxicity, and spectroscopy by investigation of molecular modifications using infrared (FTIR) and near infrared (FTNIR) spectroscopy. Further, the mitigation effects of a precursor of glutathione (GSH), N-acetylcysteine (NAC), were also assessed. Spectroscopic and genotoxicity analysis demonstrated that specific molecular changes were directly correlated with iAs exposure. Comet assay in Vicia faba showed significant effects at concentrations of 20 and 30 mg/L, depending on the structural changes involving nucleic acids as identified by FTIR and FTNIR spectroscopy. Results of phytotoxicity and micronuclei tests were significant only at higher iAs concentrations (30 mg/L), where an antioxidant effect of NAC was noted. The two spectroscopic techniques demonstrated molecular modifications predominantly associated with chemical interactions of iAs with biomolecules such as nucleic acids, carbohydrates, lipids, and proteins in Vicia faba. Our findings suggest that further studies are required to better understand the mechanisms underlying toxicity produced by different As chemical forms in vegetal and agricultural species.",
Arsenic,1337820,"NOTCH1, HIF1A and other cancer-related proteins in lung tissue from uranium miners--variation by occupational exposure and subtype of lung cancer Abstract: <strong>BACKGROUND: </strong>Radon and arsenic are established pulmonary carcinogens. We investigated the association of cumulative exposure to these carcinogens with NOTCH1, HIF1A and other cancer-specific proteins in lung tissue from uranium miners.<br /><br /><strong>METHODOLOGY/PRINCIPAL FINDINGS: </strong>Paraffin-embedded tissue of 147 miners was randomly selected from an autopsy repository by type of lung tissue, comprising adenocarcinoma (AdCa), squamous cell carcinoma (SqCC), small cell lung cancer (SCLC), and cancer-free tissue. Within each stratum, we additionally stratified by low or high level of exposure to radon or arsenic. Lifetime exposure to radon and arsenic was estimated using a quantitative job-exposure matrix developed for uranium mining. For 22 cancer-related proteins, immunohistochemical scores were calculated from the intensity and percentage of stained cells. We explored the associations of these scores with cumulative exposure to radon and arsenic with Spearman rank correlation coefficients (r(s)). Occupational exposure was associated with an up-regulation of NOTCH1 (radon r(s) = 0.18, 95% CI 0.02-0.33; arsenic: r(s) = 0.23, 95% CI 0.07-0.38). Moreover, we investigated whether these cancer-related proteins can classify lung cancer using supervised and unsupervised classification. MUC1 classified lung cancer from cancer-free tissue with a failure rate of 2.1%. A two-protein signature discriminated SCLC (HIF1A low), AdCa (NKX2-1 high), and SqCC (NKX2-1 low) with a failure rate of 8.4%.<br /><br /><strong>CONCLUSIONS/SIGNIFICANCE: </strong>These results suggest that the radiation-sensitive protein NOTCH1 can be up-regulated in lung tissue from uranium miners by level of exposure to pulmonary carcinogens. We evaluated a three-protein signature consisting of a physiological protein (MUC1), a cancer-specific protein (HIF1A), and a lineage-specific protein (NKX2-1) that could discriminate lung cancer and its major subtypes with a low failure rate.",
Arsenic,1337682,"Arsenite oxidase gene diversity among Chloroflexi and Proteobacteria from El Tatio Geyser Field, Chile Abstract: Arsenic concentrations (450-600 ?mol L(-1) ) at the El Tatio Geyser Field in northern Chile are an order of magnitude greater than at other natural geothermal sites, making El Tatio an ideal location to investigate unique microbial diversity and metabolisms associated with the arsenic cycle in low sulfide, &gt; 50 °C, and circumneutral pH waters. 16S rRNA gene and arsenite oxidase gene (aioA) diversities were evaluated from biofilms and microbial mats from two geyser-discharge stream transects. Chloroflexi was the most prevalent bacterial phylum at flow distances where arsenite was converted to arsenate, corresponding to roughly 60 °C. Among aioA-like gene sequences retrieved, most had homology to whole genomes of Chloroflexus aurantiacus, but others were homologous to alphaproteobacterial and undifferentiated beta- and gammaproteobacterial groups. No Deinococci, Thermus, Aquificales, or Chlorobi aioA-like genes were retrieved. The functional importance of amino acid sites were evaluated from evolutionary trace analyses of all retrieved aioA genes. Fifteen conserved residue sites identified across all phylogenetic groups highlight a conserved functional core, while six divergent sites demonstrate potential differences in electron transfer modes. This research expands the known distribution and diversity of arsenite oxidation in natural geothermal settings, and provides information about the evolutionary history of microbe-arsenic interactions.",
Arsenic,2278482,MRP4 (ABCC4) protects cells from arsenic through the export of dimethylarsinic acid (DMA(V)) and the diglutathione conjugate of monomethylarsonous acid (MMA(III)) Abstract: ,
Arsenic,1597341,"Involvement of oxidative stress associated with glutathione depletion and p38 mitogen-activated protein kinase activation in arsenic disulfide-induced differentiation in HL-60 cells Abstract: Arsenic disulfide (As2S2) has been traditionally used to treat certain types of leukemia. However, a detailed mechanism of action of As2S2 is not sufficiently documented. The effects of As2S2 on HL-60 cells were therefore investigated by focusing on proliferation, differentiation, generation of reactive oxygen species (ROS), intracellular glutathione (GSH) depletion and activation of p38 mitogen-activated protein kinase (MAPK). As2S2 at 0.5–8 ?M induced cell differentiation based on an increment in CD11b expression, nitroblue tetrazolium (NBT)-positive cells and cell size change. A transient increase in ROS level along with intracellular GSH level was also observed. p38 MAPK activation gradually increased after ROS generation and was sustained during cell differentiation. Decreased CD11b expression was accompanied by p38 MAPK activation, and a p38 MAPK inhibitor restored CD11b expression. The results suggest that moderate levels of oxidative stress induced by As2S2 correlate with HL-60 cell differentiation. Suppression of p38 MAPK can augment the efficacy of As2S2 to induce HL-60 cell differentiation.",
Arsenic,626936,"Fifty-year study of lung and bladder cancer mortality in Chile related to arsenic in drinking water Abstract: BACKGROUND: Region II of Chile (the second most northerly administrative region) experienced dramatic increases in average arsenic water concentrations beginning in 1958, followed by marked declines in the 1970s when water treatment plants were installed. This history provides a unique opportunity to study time trends in the development of arsenic-related cancers, including lung and bladder cancers. METHODS: We investigated lung and bladder cancer mortality from 1950 to 2000 for region II compared with region V, where drinking water was not contaminated with arsenic. Mortality data were obtained from 218,174 death certificates for the two regions for 1950-1970 and from mortality data tapes that identified 307,541 deaths in the two regions for 1971-2000. Poisson regression models were used to identify time trends in rate ratios (RRs) of mortality from lung and bladder cancers comparing region II with region V. RESULTS: Lung and bladder cancer mortality rate ratios for region II compared with region V started to increase about 10 years after high arsenic exposures commenced and continued to rise until peaking in 1986-1997. The peak lung cancer mortality RRs were 3.61 (95% confidence interval [CI] = 3.13 to 4.16) for men and 3.26 (95% CI = 2.50 to 4.23) for women. The peak bladder cancer RRs were 6.10 (95% CI = 3.97 to 9.39) for men and 13.8 (95% CI = 7.74 to 24.5) for women. Combined lung and bladder cancer mortality rates in region II were highest in the period 1992-1994, with mortality rates of 153 and 50 per 100,000 men and women, respectively, in region II compared with 54 and 19 per 100,000 in region V. CONCLUSIONS: Such large increases in total population cancer mortality rates have, to our knowledge, not been documented for any other environmental exposure. The long latency pattern is noteworthy, with mortality from lung and bladder cancers continuing to be high until the late 1990s, even though major decreases in arsenic exposure occurred more than 25 years earlier.",
Arsenic,1353980,"Effect of acute-phase and heat-shock stress on apoptosis in intestinal epithelial cells (Caco-2) Abstract: <strong>OBJECTIVES: </strong>a) To determine if the sequence of exposure of intestinal epithelial cells to heat-shock or acute-phase stimuli would affect whether cellular protection or injury would occur; and b) to determine if the effects of a thermally induced heat-shock response can be mimicked by sodium arsenite, a nonthermal inducer of the heat-shock response.<br /><br /><strong>DESIGN: </strong>In vitro controlled study.<br /><br /><strong>SETTING: </strong>Institutional laboratories.<br /><br /><strong>SUBJECTS: </strong>Caco-2 human intestinal cell line.<br /><br /><strong>INTERVENTIONS: </strong>Human intestinal epithelial cells (Caco-2) were grown on 35-mm culture dishes, chamber slides, or in a bicameral culture system to confluence or until tight-junction integrity was established. The cells were examined for viability, apoptosis, and bacterial translocation after exposure to a series of insults.<br /><br /><strong>MEASUREMENTS AND MAIN RESULTS: </strong>Control Caco-2 cells (medium only) and cells exposed to arsenite or to LPS alone had an apoptotic cell rate of 5.7%, 7.9%, and 8.6%, respectively. However, Caco-2 cells exposed to the cytokines IL-1beta and IL-6 had a significantly higher rate of apoptosis (22.1%, p &lt; .01 vs. other groups). Caco-2 cells exposed to arsenite followed by LPS had 6.7% apoptotic cells, while cells exposed to LPS followed by arsenite had a significantly greater number of apoptotic cells (19.7%, p &lt; .05). In addition, cells exposed to cytokines followed by arsenite had a higher apoptotic rate than cells exposed to arsenite followed by cytokines (28.4% vs. 10.6%, p &lt; .01). Similar results were seen when cell viability was quantitated. At 3 hrs after challenge with Escherichia coli, the cytokine-exposed Caco-2 monolayers had a significantly increased rate of bacterial passage across the Caco-2 monolayer than control monolayers (p &lt; .05), while the Caco-2 monolayers exposed to arsenite followed by cytokines or arsenite alone had a decreased rate of bacterial passage (p &lt; .05). Conversely, cells exposed to cytokines or LPS before arsenite had the highest number of bacteria crossing the monolayer (p &lt; .05).<br /><br /><strong>CONCLUSIONS: </strong>These results indicate that preinduction of a heat-shock response (arsenite) can protect against cytokine or LPS-induced apoptosis and enterocyte dysfunction, as manifested by the passage of E. coli across an intact enterocyte monolayer. In contrast, the induction of a heat-shock response after exposure to acute-phase response inducers (cytokines and LPS) may result in decreased enterocyte viability, increased apoptosis, and cellular dysfunction.",
Arsenic,1351526,Assessing Convergence and Mixing of MCMC Implementations via Stratification Abstract: ,
Arsenic,1033861,Arsenic adulteration in opium. (Arsenicosis--a real danger to health in developing countries) Abstract: ,
Arsenic,2347711,"Bioaccumulation of heavy metals by endemic Viola species from the soil in the vicinity of the As-Sb-Tl mine &quot;allchar' Republic of Macedonia Abstract: Allchar mine is an abandoned arsenic-antimony-thallium deposit located on the northwestern part of Kozuf Mt., Republic of Macedonia. Allchar is a unique deposit within the world, due to the variety of its mineral composition especially and in the high content of thallium. The aim of this work was to assess the level of contamination at this post-mining area as well as to determine the intensity of accumulation of various elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sr, Tl, V, and Zn) with focus on As, Sb and Tl, in two endemic Viola species from this locality (Viola allcharensis G. Beck, Viola arsenica G. Beck) and one Balkan endemic species (Viola macedonica Boiss. &amp; Heldr.). Samples of different plant parts and soil were digested and then analysed by ICP-AES. It was found that the accumulation of As, Sb, and Tl in these endemic species is significantly high. In this study a systematic investigation of the As-Sb-Tl contamination of soils and their bioavailability was carried out using the extraction procedure in order to explore the mobility and potential bioavailability of the As, Sb, and Tl.",
Arsenic,1022122,"Opposite effects of arsenic trioxide on the Nrf2 pathway in oral squamous cell carcinoma in vitro and in vivo Abstract: Nuclear factor erythroid derived 2 like 2 (Nrf2) is a critical transcriptional factor in mediating cellular defense mechanisms against oxidative stress or electrophiles. Arsenic has been reported to induce malignant transformation of human cells through Nrf2-dependent signaling pathway. However, arsenic is also a promising cancer therapeutic drug for solid tumors, including oral squamous cell carcinoma (OSCC). It is still unclear how Nrf2 may mediate cellular response of OSCC cells when treated with arsenic. In order to fully understand the impact of arsenic on Nrf2 signaling in human OSCC, we examined expression of Nrf2 and Nrf2-regulated genes in arsenic trioxide (ATO)-treated OSCC cells in vitro and in ATO-treated OSCC xenografts. ATO had anti-cancer effects on both cultured OSCC cells and OSCC xenografts by inhibiting cell growth, suppressing angiogenesis and inducing apoptosis. ATO activated a silent Nrf2 pathway in cultured OSCC cells as shown by induction of Nrf2 and Nrf2-regulated genes, NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), in a dose-dependent manner. On the contrary, Nrf2 pathway became active in OSCC xenograft tumors, and ATO treatment down-regulated expression of Nrf2 and Nrf2-regulated genes. Our study clearly demonstrated opposite effects of ATO on Nrf2 pathway in OSCC cells in vitro and in vivo.",
Arsenic,1017059,"Stress proteins induced by arsenic Abstract: The elevated expression of stress proteins is considered to be a universal response to adverse conditions, representing a potential mechanism of cellular defense against disease and a potential target for novel therapeutics. Exposure to arsenicals either in vitro or in vivo in a variety of model systems has been shown to cause the induction of a number of the major stress protein families such as heat shock proteins (Hsp). Among them are members with low molecular weight, such as metallotionein and ubiquitin, as well as ones with masses of 27, 32, 60, 70, 90, and 110 kDa. In most of the cases, the induction of stress proteins depends on the capacity of the arsenical to reach the target, its valence, and the type of exposure, arsenite being the biggest inducer of most Hsp in several organs and systems. Hsp induction is a rapid dose-dependent response (1-8 h) to the acute exposure to arsenite. Thus, the stress response appears to be useful to monitor the sublethal toxicity resulting from a single exposure to arsenite. The present paper offers a critical review of the capacity of arsenicals to modulate the expression and/or accumulation of stress proteins. The physiological consequences of the arsenic-induced stress and its usefulness in monitoring effects resulting from arsenic exposure in humans and other organisms are discussed.",
Arsenic,627189,"Conditioned flavor aversion and brain Fos expression following exposure to arsenic Abstract: Recent advances in the knowledge of the cellular effects of arsenic have provided insights into the molecular mechanisms of arsenic-associated carcinogenesis, immunotoxicity and cardiovascular disease. In the present experiments we tested the hypothesis that the arrival of arsenic to the gastrointestinal (GI) tract is detected by the gut-brain axis, which includes hindbrain and forebrain nuclei activated by GI stimulation. As a marker of neuronal activation we measured Fos expression using immunohistochemistry. Because Fos expression in these nuclei is closely linked to the development of conditioned flavor aversion (CFA) we also tested the effect of arsenic on CFA. Our experiments indicate that arsenic ingestion is readily detected by the brain, as shown by increased Fos expression after oral administration of arsenic. Furthermore, the vagus nerve, which supplies information from the GI tract to the brain, is not involved in this response because a complete subdiaphragmatic vagotomy did not reduce the effect of arsenic on brain Fos expression, but enhanced this response. In parallel, arsenic ingestion is associated with a robust, dose-dependent CFA, which started at doses as low as 0.1 mg/kg body weight. In summary, these data indicate that arsenic given by oral administration is detected by the brain in low concentrations, and activates specific nuclei, which might trigger behavioral responses, such as CFA.",
Arsenic,1579242,"Accumulation, transformation, and release of inorganic arsenic by the freshwater cyanobacterium Microcystis aeruginosa Abstract: Arsenic (As) as a major hazardous metalloid was affected by phytoplankton in many aquatic environments. The toxic dominant algae Microcystis aeruginosa was exposed to different concentrations of inorganic arsenic (arsenate or arsenite) for 15 days in BG11 culture media. Arsenic accumulation, toxicity, and speciation in M. aeruginos as well as the changes of As species in media were examined. M. aeruginosa has a general well tolerance to arsenate and a definite sensitivity to arsenite. Additionally, arsenate actively elevated As methylation by the algae but arsenite definitely inhibited it. Interestingly, the uptake of arsenite was more pronounced than that of arsenate, and it was correlated to the toxicity. Arsenate was the predominant species in both cells and their growth media after 15 days of exposure to arsenate or arsenite. However, the amount of the methylated As species in cells was limited and insignificantly affected by the external As concentrations. Upon uptake of the inorganic arsenic, significant quantities of arsenate as well as small amounts of arsenite, DMA, and MMA were produced by the algae and, in turn, released back into the growth media. Bio-oxidation was the first and primary process and methylation was the minor process for arsenite exposures, while bioreduction and the subsequent methylation were the primary metabolisms for arsenate exposures. Arsenic bioaccumulation and transformation by M. aeruginosa in aquatic environment should be paid more attention during a period of eutrophication.",
Arsenic,1070401,"Arsenic and chromium speciation in an urban contaminated soil Abstract: The distribution and speciation of As and Cr in a contaminated soil were studied by synchrotron-based X-ray microfluorescence (?-XRF), microfocused X-ray absorption spectroscopy (?-XAS), and bulk extended X-ray absorption fine structure spectroscopy (EXAFS). The soil was taken from a park in Wilmington, DE, which had been an important center for the leather tanning industry along the Atlantic seaboard of the United States, until the early 20th century. Soil concentrations of As, Cr, and Pb measured at certain locations in the park greatly exceeded the background levels of these heavy metals in the State of Delaware. Results show that Cr(III) and As(V) species are mainly present in the soil, with insignificant amounts of Cr(VI) and As(III). Micro-XRF maps show that Cr and Fe are distributed together in regions where their concentrations are diffuse, and at local spots where their concentrations are high. Iron oxides, which can reduce Cr(VI) to Cr(III), are present at some of these hot spots where Cr and Fe are highly concentrated. Arsenic is mainly associated with Al in the soil, and to a minor extent with Fe. Arsenate may be sorbed to aluminum oxides, which might have transformed after a long period of time into an As-Al precipitate phase, having a structure and chemical composition similar to mansfieldite (AlAsO(4)?2H(2)O). The latter hypothesis is supported by the fact that only a small amount of As present in the soil was desorbed using the characteristic toxicity leaching procedure tests. This suggests that As is immobilized in the soil.",
Arsenic,1677524,"Blood mineral concentrations in manatees (Trichechus manatus latirostris and Trichechus manatus manatus) Abstract: Limited information is available regarding the role of minerals and heavy metals in the morbidity and mortality of manatees. Whole-blood and serum mineral concentrations were evaluated in apparently healthy, free-ranging Florida (Trichechus manatus latirostris, n = 31) and Belize (Trichechus manatus manatus, n = 14) manatees. Toxicologic statuses of the animals and of their environment had not been previously determined. Mean mineral whole-blood (WB) and serum values in Florida (FL) and Belize (BZ) manatees were determined, and evaluated for differences with respect to geographic location, relative age, and sex. Mean WB and serum silver, boron, cobalt, magnesium, molybdenum, and WB cadmium concentrations were significantly higher in BZ versus FL manatees (P &lt; 0.05). Mean WB aluminum, calcium, manganese, sodium, phosphorus, vanadium, and serum zinc concentrations were significantly lower in BZ versus FL manatees. Adult manatees had significant and higher mean WB aluminum, manganese, sodium, antimony, vanadium, and serum manganese and zinc concentrations compared to juvenile animals. Significant and lower mean WB and serum silver, boron, cobalt, and serum copper and strontium concentrations were present in adults compared to juveniles (P &lt; or = 0.05). Females had significant and higher mean WB nickel and serum barium compared to males (P &lt; or = 0.05). Mean WB arsenic and zinc, and mean serum iron, magnesium, and zinc concentrations fell within toxic ranges reported for domestic species. Results reveal manatee blood mineral concentrations differ with location, age, and sex. Influence from diet, sediment, water, and anthropogenic sources on manatee mineral concentration warrant further investigation.",
Arsenic,2343444,"Localization and speciation of arsenic in Glomus intraradices by synchrotron radiation spectroscopic analysis Abstract: The protective mechanisms employed by arbuscular mycorrhizal fungi (AMF) to reduce the toxic effects of arsenic on host plants remain partially unknown. The goal of this research was identifying the in situ localization and speciation of arsenic (As) in the AM fungus Rhizophagus intraradices [formerly named Glomus intraradices] exposed to arsenate [As(V)]. By using a two-compartment in vitro fungal cultures of R. intraradices-transformed carrot roots, microspectroscopic X-ray fluorescence (?-XRF), and microspectroscopic X-ray absorption near edge structure (?-XANES), we observed that As(V) is absorbed after 1 h in the hyphae of AMF. Three hours after exposure a decrease in the concentration of As was noticed and after 24 and 72 h no detectable As concentrations were perceived suggesting that As taken up was pumped out from the hyphae. No As was detected within the roots or hyphae in the root compartment zone three or 45 h after exposure. This suggests a dual protective mechanism to the plant by rapidly excluding As from the fungus and preventing As translocation to the plant root. ?-XANES data showed that gradual As(V) reduction occurred in the AM hyphae between 1 and 3 h after arsenic exposure and was completed after 6 h. Principal component analysis (PCA) and linear combination fitting (LCF) of ?-XANES data showed that the dominant species after reduction of As(V) by R. intraradices extra-radical hyphal was As(III) complexed with a reduced iron(II) carbonate compound. The second most abundant As species present was As(V)-iron hydroxides. The remaining As(III) compounds identified by the LCF analyses suggested these molecules were made of reduced As and S. These results increase our knowledge on the mechanism of As transport in AMF and validate our hypotheses that R. intraradices directly participates in arsenic detoxification. These fungal mechanisms may help AMF colonized plants to increase their tolerance to As at contaminated sites.",
Arsenic,1337664,"Total and inorganic arsenic in natural and aquacultural freshwater fish in Thailand: a comparative study Abstract: Total and inorganic arsenic were determined in 108 samples of four freshwater fish species collected from natural water sources and aquaculture systems in the central region of Thailand between March and May 2010. Concentrations of total and inorganic arsenic (dry wt) and percentages of inorganic arsenic in four aquacultural fish species were not significantly different from those found in natural fish. Inorganic arsenic levels found in the four fish species from both sources in this study were much lower than the Thai regulatory standard of 2 ?g/g, and hence are considered safe for human consumption.",
Arsenic,2064285,"Arsenic species in drinking water wells in the USA with high arsenic concentrations Abstract: Arsenic exists in ground water as oxyanions having two oxidation states, As(III) and As(V), and its concentrations vary widely and regionally across the United States (USA). Because of the difference in toxicity and removability of As(III) and As(V), arsenic speciation is important in the selection and design of an arsenic treatment systems. Identifying the arsenic species is also helpful in explaining and understanding the behavior and characteristics of arsenic in the environment. Although laboratory methods exist for speciating arsenic in water samples, the lack of a universal preservation method has led to the predominant use of field separation methods that are somewhat complex and costly. Thus, very few studies have incorporated arsenic speciation. A U.S. Environmental protection Agency (EPA) arsenic treatment research program provided a unique opportunity to speciate the naturally occurring arsenic in 65 well waters scattered across the USA with many of them being speciated monthly for up to three years. Speciation test data showed that 31 wells had predominantly As(V), 29 had predominantly As(III) and five had a mixture of both. A general pattern was found where As(III) was the dominant species in midwest ground waters where anoxic conditions and elevated iron concentrations prevailed and the well waters in the east, west and farwest had either As(III) or As(V) as the dominant species. The monthly (12-36) speciation tests results at many of these sites also found no major changes in arsenic species over time.",
Arsenic,1519158,The impact of GPX1 on the association of groundwater selenium and depression: a project FRONTIER study Abstract: ,
Arsenic,1018429,"Neutrophil-associated inflammatory responses in rats are inhibited by phenylarsine oxide Abstract: NADPH oxidase is a phagocyte-specific enzyme which produces O2- and so initiates a cascade of reactive oxygen species formation. Inflammatory diseases involve overproduction of reactive oxygen species which induce tissue damage. Phenylarsine oxide has been described previously as a complete and direct inhibitor of NADPH oxidase in vitro that acts by covalently binding to vicinal thiol groups of a membrane-associated component of the enzyme. In the present work, the potential anti-inflammatory effect of phenylarsine oxide was tested on two experimental models in rats, carrageenan-induced paw oedema and lipopolysaccharide-mediated lung inflammation. Intraperitoneal injection of phenylarsine oxide reduced (i) reactive oxygen species production by rat phagocytes, (ii) neutrophil infiltration into the lung after inhalation of lipopolysaccharide and (iii) neutrophil-dependent oedema induced by carrageenan in hindpaws. We conclude that phenylarsine oxide has anti-inflammatory properties which are probably exerted by its ability to inhibit neutrophil NADPH oxidase-dependent reactive oxygen species production. The present work provides the basis for the development of new anti-inflammatory, arsenic-free agents reacting at the phenylarsine oxide site, which seems to be the Achilles' heel of NADPH oxidase.",
Arsenic,2345637,"Associations between land cover categories, soil concentrations of arsenic, lead and barium, and population race/ethnicity and socioeconomic status Abstract: The potential of using land cover/use categories as a proxy for soil metal concentrations was examined by measuring associations between Anderson land cover category percentages and soil concentrations of As, Pb, and Ba in ten sampling areas. Land cover category and metal associations with ethnicity and socioeconomic status at the United States Census 2000 block and block group levels also were investigated. Arsenic and Pb were highest in urban locations; Ba was a function of geology. Consistent associations were observed between urban/built up land cover, and Pb and poverty. Land cover can be used as proxy for metal concentrations, although associations are metal-dependent.",
Arsenic,628714,"Arsenite induces endothelial cytotoxicity by down-regulation of vascular endothelial nitric oxide synthase Abstract: Epidemiological studies have demonstrated a high association of inorganic arsenic exposure with vascular diseases. Recent research has also linked this vascular damage to impairment of endothelial nitric oxide synthase (eNOS) function by arsenic exposure. However, the role of eNOS in regulating the arsenite-induced vascular dysfunction still remains to be clarified. In our present study, we investigated the effect of arsenite on Akt1 and eNOS and its involvement in cytotoxicity of vascular endothelial cells. Our study demonstrated that arsenite decreased the protein levels of both Akt1 and eNOS accompanied with increased levels of ubiquitination of total cell lysates. We found that inhibition of the ubiquitin–proteasome pathway by MG-132 could partially protect Akt1 and eNOS from degradation by arsenite together with a proportional protection from the arsenite-induced cytoxicity. Moreover, up-regulation of eNOS protein expression significantly attenuated the arsenite-induced cytotoxicity and eNOS activity could be significantly inhibited after incubation with arsenite for 24 h in a cell-free system. Our study indicated that endothelial eNOS activity could be attenuated by arsenite via the ubiquitin–proteasome-mediated degradation of Akt1/eNOS as well as via direct inhibition of eNOS activity. Our study also demonstrated that eNOS actually played a protective role in arsenite-induced cytoxicity. These observations supported the hypothesis that the impairment of eNOS function by arsenite is one of the mechanisms leading to vascular changes and diseases.",
Arsenic,1597407,"Cysteine accessibility during As3+ metalation of the alpha- and beta-domains of recombinant human MT1a Abstract: Metallothionein is a ubiquitous metal binding protein that plays an important role in metal ion homeostasis and redox chemistry within cells. Mammalian metallothioneins bind a wide variety of metals including the metalloid As3+ in two domains (? and ?) connected by a short linker sequence. Three As3+ bind in each domain for a total of 6 As3+ per protein. In recombinant human metallothionein (rh-MT1a) each As3+ binds three cysteine residues to form As3Cys9(CysSH)2-?-rhMT1a in the 11 Cys ?-domain and As3Cys9-?-rhMT1a in the 9 Cys ?-domain. This means that there should be 2 free cysteines in the ?-domain but no free cysteines in the ?-domain. By using benzoquinone, the number and relative accessibility of the free cysteinyl thiols during the metalation reactions were determined. The electrospray ionization mass spectrometry (ESI-MS) data confirmed that each As3+ binds using exactly 3 cysteine thiols and showed that there was a significant difference in the reactivity of the free cysteines during the metalation reaction. After a reaction with two molar equivalents of As3+ to form As2Cys6(CysSH)3-??-rhMT1a, the remaining 3 Cys in the 9 Cys ?-domain were far less reactive than those in the ?-domain. Molecular dynamics calculations for the metalation reactions with As3+ measured by ESI-MS allowed an interpretation of the mass spectral data in terms of the relative location of the cysteine thiols that were not involved in As3+ coordination. Together, these data provide insight into the selection of a specific cysteinyl thiol by the incoming metals during the stepwise metalation of metallothioneins.",
Arsenic,628711,"Dose-response relationship between peripheral vascular disease and ingested inorganic arsenic among residents in Blackfoot disease endemic villages in Taiwan Abstract: The purpose of this study was to examine the correlation between previous arsenic exposure and peripheral vascular disease after stopping consumption of high-arsenic artesian well water for more than two decades in blackfoot disease endemic villages in Taiwan. A total of 582 adults (263 men and 319 women, aged 52.6 ± 10.6 years) living in these villages underwent Doppler ultrasound measurement of systolic pressures on bilateral ankle (posterior tibial and dorsal pedal) and brachial arteries and estimation for long-term arsenic exposure. The diagnosis of peripheral vascular disease was based on an ankle-brachial index (the ratio between ankle and brachial systolic pressures) < 0.90 on either side. Three indices of arsenic exposure were estimated: (1) duration of living in blackfoot disease endemic villages; (2) duration of artesian well water consumption; and (3) cumulative arsenic exposure in mg/1-years based on the detailed history of residential addresses and artesian well water consumption and the arsenic concentration in artesian well water. Multiple logistic regression analysis was used to assess the association between peripheral vascular disease and arsenic exposure. A dose-response relation was observed between the prevalence of peripheral vascular disease and the long-term arsenic exposure. The odds ratios (95% confidence intervals) after adjustment for age, sex, body mass index, cigarette smoking, serum cholesterol and triglyceride levels, diabetes mellitus and hypertension were 2.77 (0.84–9.14), and 4.28 (1.26–14.54) for those who had cumulative arsenic exposure of 0.1–19.9 and ? 20.0 mg/1-years, respectively, compared with those who were not exposed. This study suggests a close relation between long-term arsenic exposure and peripheral vascular disease in blackfoot disease endemic villages in Taiwan after stopping consumption of artesian well water.",
Arsenic,1794785,Root iron plaque formation and characteristics under N-2 flushing and its effects on translocation of Zn and Cd in paddy rice seedlings (Oryza sativa) Abstract: ,
Arsenic,474398,"Heavy metal concentrations in the general population of Andalusia, South of Spain - A comparison with the population within the area of influence of Aznalcollar mine spill (SW Spain) Abstract: Levels of metalloids (As - urine) and heavy metals (Hg - urine, Cd - whole blood and Zn - serum) were determined by atomic absorption spectrometry in 601 subjects living in the area affected by the Aznalcollar mine spill (SW, Spain) and compared with those of a representative sample (960 subjects) selected from the Andalusian community (non-affected area), southern Spain. The characteristic parameters of the analytical method including uncertainty were determined for each metal. Potential associations of metal concentration with age, sex and body mass index as well as life-style habits (smoking, alcohol consumption and food habits) were explored. Concentrations of all the metals studied were statistically higher in the population of the affected area with respect to that of the non-affected area in Andalusia, although levels were always lower or similar to the values reported for the general population and below occupational reference limits. In conclusion, there is a lack of evidence that the spill had any incidence on human health in the population living in the affected area. There are few references in scientific literature reporting values from large series of samples, and hence our data could be useful for further studies. (c) 2006 Elsevier B.V. All rights reserved.",
Arsenic,1025494,"Establishment of an immunoglobulin m antibody-forming cell response model for characterizing immunotoxicity in primary human B cells Abstract: Rodent models have been extensively utilized to identify putative human immunotoxicants; however, even when immunotoxicity is established, uncertainty remains whether the effects are predictive of human risk. Therefore, the objective of this study was to establish a polyclonal immunoglobulin M (IgM) antibody-forming cell (AFC) response model to directly characterize immunotoxicity in primary mouse or human B cells. CD40 ligand (CD40L) was selected to activate B cells because it effectively drives both primary human and mouse B cells in vitro to AFC in a physiologically relevant manner to mimic T-cell-dependent antibody responses in vivo. In this model, the IgM AFC response is induced by cell surface-expressed CD40L and promoted by recombinant cytokines. Reported here are the conditions required to induce IgM AFC responses using mouse splenic B cells or human peripheral blood B cells, allowing for species comparisons. Moreover, less than one order of magnitude difference was observed in the CD40L-induced B-cell AFC responses based on data from multiple donors. In addition to antibody production, proliferation and phenotypic changes characteristic of B-cell activation as well as the plasma cell phenotype were also significantly induced. Finally, two well-characterized immunotoxicants, arsenic and benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide, using the CD40L-induced IgM AFC response were compared in both mouse and human B cells. Collectively, an IgM AFC response model is described that can be applied to assess the sensitivity of antibody responses to modulation by xenobiotics using mouse as well as human primary B cells.",
Arsenic,710856,"Arsenite induces apoptosis in human mesenchymal stem cells by altering Bcl-2 family proteins and by activating intrinsic pathway Abstract: Environmental exposure to arsenic is an important public health issue. The effects of arsenic on different tissues and organs have been intensively studied. However, the effects of arsenic on bone marrow mesenchymal stem cells (MSCs) have not been reported. This study is designed to investigate the cell death process caused by arsenite and its related underlying mechanisms on MSCs. The rationale is that absorbed arsenic in the blood circulation can reach to the bone marrow and may affect the cell survival of MSCs.<br /><br /> MSCs of passage 1 were purchased from Tulane University, grown till 70% confluency level and plated according to the experimental requirements followed by treatment with arsenite at various concentrations and time points. Arsenite (iAs(III)) induced cytotoxic effects were confirmed by cell viability and cell cycle analysis. For the presence of canonic apoptosis markers; DNA damage, exposure of intramembrane phosphotidylserine, protein and m-RNA expression levels were analyzed.<br /><br /> iAs(III) induced growth inhibition, G2-M arrest and apoptotic cell death in MSCs, the apoptosis induced by iAs(III) in the cultured MSCs was, via altering Bcl-2 family proteins and by involving intrinsic pathway.<br /><br /> iAs(III) can induce apoptosis in bone marrow-derived MSCs via Bcl-2 family proteins, regulating intrinsic apoptotic pathway. Due to the multipotency of MSC, acting as progenitor cells for a variety of connective tissues including bone, adipose, cartilage and muscle, these effects of arsenic may be important in assessing the health risk of the arsenic compounds and understanding the mechanisms of arsenic-induced harmful effects.",
Arsenic,1352375,DETECTION OF ELEMENTS AT ALL THREE r-PROCESS PEAKS IN THE METAL-POOR STAR HD 160617 Abstract: ,
Arsenic,1256733,"Genome sequence of the moderately halotolerant, arsenite-oxidizing bacterium Pseudomonas stutzeri TS44 Abstract: We present the draft genome sequence of Pseudomonas stutzeri TS44, a moderately halotolerant, arsenite-oxidizing bacterium isolated from arsenic-contaminated soil. The genome contains genes for arsenite oxidation, arsenic resistance, and ectoine/hydroxyectoine biosynthesis. The genome information will be useful for exploring adaptation of P. stutzeri TS44 to an arsenic-contaminated environment.",
Arsenic,1936138,"Comparison of the IFDM building downwash model predictions with field data Abstract: The building downwash parameterization for plume models proposed in Cosemans et al. (2012) is integrated in a plume model (IFDM, Immission Frequency Distribution Model) and the predictions of this model are compared with real-life field data. The field data are time series for four monitoring sites of daily arsenic (As) concentrations measured over a two year period (Jan. 2010-Dec. 2011) near a plant that emits some As. In-stack emission measurements as well as measured As concentrations in ambient air show considerable time-dependent variations which prohibited a straightforward comparison of measured and computed concentrations using average emissions. Therefore, two model evaluations have been done. First, the time-variability was considered small enough during twenty months (out of the 24 months in the two-year period) to compare the central moving averages of the measured concentrations with those computed using constant emissions. Time series compare well, and none of the measured annual average concentrations has a bias larger than 50% while 7 out of 8 year averages (4 monitoring sites, two years) have a bias lower than 30%. During the four months not used in this evaluation, measured daily concentrations are about four times higher than during the other twenty months, resulting in yearly average increase up to 80%. Using a time-varying emission scenario, using information from daily As-measurements in the recirculation zone on top of the building with the sources, the model is able to reproduce the annual mean concentrations at the different locations including all the months. Finally, not only the yearly averages, but also the time series of measured and computed concentrations, pollutant roses and Q Q plots are evaluated. (C) 2013 Elsevier Ltd. All rights reserved.",
Arsenic,2149365,"Evaluating effective reaction rates of kinetically driven solutes in large-scale, anisotropic media: human health risk implications Abstract: ",
Arsenic,1030236,"Neutron activation analysis of arsenic in normal skin, keratoses, and epitheliomas Abstract: ",
Arsenic,1015774,"A Novel Aquaporin 3 in Killifish (Fundulus heteroclitus) is Not an Arsenic Channel Abstract: The Atlantic killifish (Fundulus heteroclitus) is a model environmental organism that has an extremely low assimilation rate of environmental arsenic. As a first step in elucidating the mechanism behind this phenomenon, we used Q-RT-PCR to identify aquaglyceroporins (AQPs), which are arsenite transporters, in the killifish gill. A novel homolog killifish AQP3 (kfAQP3a) was cloned from the killifish gill, and a second homolog was identified as the consensus from a transcriptome database (kfAQP3b). The two were 99% homologous to each other, 98% homologous to a previously identified killifish AQP3 from embryos (kfAQP3ts), and 78% homologous to hAQP3. Expression of kfAQP3a in Xenopus oocytes significantly enhanced water, glycerol and urea transport. However, kfAQP3a expressed in HEK293T cells did not transport significant amounts of arsenic. All sequence motifs thought to confer the ability of AQP3 to transport solutes were conserved in kfAQP3a, kfAQP3b, and kfAQP3ts: however, the C-terminal amino acids were different in kfAQP3a versus the other two homologs. Replacement of the three C-terminal amino acids of kfAQP3 (GKS) with the three C-terminal amino acids of kfAQP3b and kfAQP3ts (ANC) was sufficient to enable kfAQP3a to robustly transport arsenic. Thus, the C-terminus of kfAQP3b and kfAQP3ts confers arsenic selectivity in kfAQP3. Moreover, kfAQP3a, the only aquaglyceroporin expressed in killifish gill, is the first aquaglyceroporin identified that does not transport arsenic, which may explain, in part, why killifish poorly assimilate arsenic and are highly tolerant to environmental arsenic.",
Arsenic,1936038,"Identification of Novel ?-N-Methylation of CENP-B That Regulates Its Binding to the Centromeric DNA Abstract: The eukaryotic centromere is an essential chromatin region required for accurate segregation of sister chromatids during cell division. Centromere protein B (CENP-B) is a highly conserved protein which can bind to the 17-bp CENP-B box on the centromeric DNA. In this study, we found that CENP-B could be ?-N-methylated in human cells. We also showed that the level of the ?-N-methylation was stimulated in cells in response to a variety of extracellular stimuli, including increased cell density, heat shock, and arsenite treatment, although the methylation level was not altered upon metaphase arrest. We identified N-terminal RCC1 methyltransferase (NRMT) as a major enzyme required for the CENP-B methylation. Additionally, we found that chromatin-bound CENP-B was primarily trimethylated and ?-N-trimethylation could enhance CENP-B's binding to CENP-B box in cells. Our study also expands the function of protein ?-N-methylation that has been known for decades and whose function remains largely unexplored.",
Arsenic,2278493,"Effects of co-exposure to arsenic and dichlorvos on glutathione metabolism, neurological, hepatic variables and tissue histopathology in rats Abstract: The individual toxic effects of arsenic and organophosphate pesticides are known but there is a lack of data on their combined effects. The present study investigates the toxic effects following combined exposure to organophosphate and arsenic on: (i) alterations in brain biogenic amines, (ii) oxidative stress and its correlation with glutathione linked enzymes, cell death and histopathological observations, and (iii) arsenic concentration in soft tissues. Rats were exposed to arsenic (1 mg kg(-1) body weight, orally) and dichtorvos (4 mg kg(-1) body weight, subcutaneously) either individually or in combination for 16 weeks. Arsenic alone and in combination with DDVP led to a significant increase in reactive oxygen species (ROS), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities accompanied by a decreased glutathione reductase, reduced and oxidized glutathione (GSH and GSSG) levels in tissues. Arsenic and DDVP also produced a significant depletion in brain biogenic amines; however, acetylcholinesterase (AChE) activity increased moderately on arsenic exposure. Arsenic and DDVP co-exposure exhibited synergism in the case of ROS while no such effect was noted in the case of TBARS. Interestingly, combined exposure to arsenic and DDVP resulted in more pronounced toxic effects compared to their individual effects based on various biochemical variables, cell death (TUNEL assay) and histopathological observations. Interestingly, brain arsenic levels decreased on co-exposure to arsenic and DDVP accompanied with prominent elevation of liver arsenic content in co-exposed groups. The present study thus provides some interesting observations on the interaction between arsenic and DDVP including (i) co-exposure to arsenic and DDVP might lead to significant oxidative stress and (ii) their co-exposure produced synergistic effects on some liver variables but some antagonistic effects on the brain.",
Arsenic,2347789,"Performances of methyl blue and arsenic(V) adsorption from aqueous solution onto magnetic 0.8Ni(0.5)Zn(0.5)Fe(2)O(4)/0.2SiO(2) nanocomposites Abstract: Magnetic 0.8Ni(0.5)Zn(0.5)Fe(2)O(4)/0.2SiO(2) nanocomposites were prepared by the facile citrate-gel thermal decomposition process. Their microstructure and magnetic properties were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and vibrating sample magnetometer (VSM). The as-prepared magnetic 0.8Ni(0.5)Zn(0.5)Fe(2)O(4)/0.2SiO(2) nanocomposites were characterized with about 8-nm grains, specific surface area of 119.3 m(2)/g, and magnetization of 38.7 Am-2/kg. The adsorption kinetics and adsorption isotherms of methyl blue (MB) and As(V) onto the magnetic 0.8Ni(0.5)Zn(0.5)Fe(2)O(4)/0.2SiO(2) nanocomposites at room temperature were investigated. Adsorption kinetics of MB and As(V) onto the magnetic 0.8Ni(0.5)Zn(0.5)Fe(2)O(4)/0.2SiO(2) nanocomposites have been researched using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, the statistic results show that the pseudo-second-order kinetic model is fitted well to describe the MB and As(V) adsorption process. The adsorption equilibrium data of MB and As(V) onto the magnetic 0.8Ni(0.5)Zn(0.5)Fe(2)O(4)/0.2SiO(2) nanocomposites at room temperature were analyzed with Langmuir, Freundlich, and Temkin models, and the adsorption isotherms was more effectively described by the Freundlich model based on the values of the correlation coefficient.",
Arsenic,1033320,"Analysis of total arsenic in urine and blood by high speed anodic stripping voltammetry Abstract: A method for the measurement of parts per billion levels of total arsenic in urine and blood is described. Samples are wet ashed with a mixture of HNO3, HCIO4, and H2SO4 acids. Ashed materials are subjected to a reductillationTM procedure to reduce As (V) to As (III) and to separate arsenic from the sample matrix. Collected arsenic is then quantitated by anodic stripping voltammetry (ASV) at a gold film electrode. ASV analysis time is only 2 minutes. By simultaneous reductillation of 4 samples, ppb arsenic determinations can be accomplished at a rate of about 12 per hour. The method is as accurate, precise and reliable at the nanogram level as the more universally accepted colorimetric techniques are at the microgram and milligram levels. For replicate analysis of real samples, method precision ranged from +/- 1.4 ppb at the 5 ppb level to +/- 0.96 ppb at the 25 ppb level. Accuracy is estimated at +/- 6% over the range 5 to 500 ppb arsenic.",
Arsenic,1597344,"Computational identification and analysis of arsenate reductase protein in Cronobacter sakazakii ATCC BAA-894 suggests potential microorganism for reducing arsenate Abstract: This study focuses a bioinformatics-based prediction of arsC gene product arsenate reductase (ArsC) protein in Cronobacter sakazakii BAA-894 strain. A protein structure-based study encloses three-dimensional structural modeling of target ArsC protein, was carried out by homology modeling method. Ultimately, the detection of active binding regions was carried out for characterization of functional sites in protein. The ten probable ligand binding sites were predicted for target protein structure and highlighted the common binding residues between target and template protein. It has been first time identified that modeled ArsC protein structure in C. sakazakii was structurally and functionally similar to well-characterized ArsC protein of Escherichia coli because of having same structural motifs and fold with similar protein topology and function. Investigation revealed that ArsC from C. sakazakii can play significant role during arsenic resistance and potential microorganism for bioremediation of arsenic toxicity.",
Arsenic,1018809,"Male reproductive effect of arsenic in mice Abstract: Arsenic, a known human carcinogen, was given to mice via drinking water as sodium arsenite at a dose 53.39, 133.47, 266.95 and 533.90 micromol 1 for 35 days. A decrease in the activity of 17 beta HSD along with increase in LDH, gammaGT activity were observed at 533.90 micromol l. The observed sperm count, motility and morphological abnormalities in sperm were similar to control at lower dose levels. However at 533.90 micromol l a significant decrease in sperm count and motility along with increase in abnormal sperm were noticed. Significant accumulation of arsenic in testes and accessory sex organs may be attributed to the arsenic binding to the tissues or greater cellular uptake. No effects were observed on indices studied for reproductive effects at 53.39 micromol l arsenic close to which human being are exposed through drinking water under the present set of experimental conditions.",
Arsenic,1070470,"Accounting for water quality in monitoring access to safe drinking-water as part of the Millennium Development Goals: Lessons from five countries Abstract: OBJECTIVE: To determine how data on water source quality affect assessments of progress towards the 2015 Millennium Development Goal (MDG) target on access to safe drinking-water. METHODS: Data from five countries on whether drinking-water sources complied with World Health Organization water quality guidelines on contamination with thermotolerant coliform bacteria, arsenic, fluoride and nitrates in 2004 and 2005 were obtained from the Rapid Assessment of Drinking-Water Quality project. These data were used to adjust estimates of the proportion of the population with access to safe drinking-water at the MDG baseline in 1990 and in 2008 made by the Joint Monitoring Programme for Water Supply and Sanitation, which classified all improved sources as safe. FINDINGS: Taking account of data on water source quality resulted in substantially lower estimates of the percentage of the population with access to safe drinking-water in 2008 in four of the five study countries: the absolute reduction was 11% in Ethiopia, 16% in Nicaragua, 15% in Nigeria and 7% in Tajikistan. There was only a slight reduction in Jordan. Microbial contamination was more common than chemical contamination. CONCLUSION: The criterion used by the MDG indicator to determine whether a water source is safe can lead to substantial overestimates of the population with access to safe drinking-water and, consequently, also overestimates the progress made towards the 2015 MDG target. Monitoring drinking-water supplies by recording both access to water sources and their safety would be a substantial improvement.",
Arsenic,519461,"Twenty years of the German Environmental Survey (GerES): Human biomonitoring - Temporal and spatial (West Germany/East Germany) differences in population exposure Abstract: The German Environmental Surveys (GerESs) are nationwide population studies, which have repeatedly been carried out in Germany since the mid-1980s. The subjects were representatively selected from the regional registration offices with regard to age, gender and community size. The first survey for adults (GerES I) was carried out in 1985/1986 (West Germany) followed by GerES IIa in 1990/1991 (West Germany) and GerES IIb in 1991/1992 (East Germany). In GerES II children were also included to some extent. In 1998, the third GerES for adults was conducted in both parts of Germany (GerES III). The current survey 2003/2006 (GerES IV) is focussing exclusively on children. A 1-year pilot study was conducted in 2001-2002 to collect information on parameters influencing the response rate and to test the suitability of the different instruments intended to be used for the main study. The main goal of the surveys is to analyse and document the extent, distribution and determinants of exposure to environmental pollutants of the German general population. Three main instruments of investigation were comprised in GerES: human biomonitoring (HBM), monitoring of the domestic environment, and collecting information on exposure pathways and living conditions via questionnaires. This paper is focussed on the general design of the GerESs, the trend over time and spatial differences (West Germany and East Germany) for HBM data on arsenic, cadmium, lead, mercury, pentachlorophenol (PCP), and polycyclic aromatic hydrocarbons (PAH). These substances have been determined in blood and/or morning urine of adults and children. All GerESs have been conducted in close connection with the National Health Interview and Examination Surveys performed by the Robert Koch-Institute, Berlin. (C) 2007 Elsevier GmbH. All rights reserved.",
Arsenic,1026575,"Effects of sodium arsenite on catalase activity, gene and protein expression in HaCaT cells Abstract: The objective of this research work is to study the effects of sodium arsenite on activity, mRNA and protein expression of catalase (CAT) in established human cell lines of keratinocytes (HaCaT). Based on the AlamarBlue assay, we found that a high level (100 micromol/l) of sodium arsenite inhibited cell viability. The reactive oxygen species (ROS) content in cells was increased in all treated cultures dose-dependently. CAT activity, mRNA expression and protein levels were decreased by 5-20 micromol/l of sodium arsenite. It is highly suggestive that CAT gene expression and protein levels are affected by arsenic.",
Arsenic,2149127,"Comparison of genome-wide DNA methylation in urothelial carcinomas of patients with and without arsenic exposure Abstract: <strong>BACKGROUND: </strong>Arsenic is a well-documented carcinogen of human urothelial carcinoma (UC) with incompletely understood mechanisms.<br /><br /><strong>OBJECTIVES: </strong>This study aimed to compare the genome-wide DNA methylation profiles of arsenic-induced UC (AsUC) and non-arsenic-induced UC (Non-AsUC), and to assess associations between site-specific methylation levels and cumulative arsenic exposure.<br /><br /><strong>METHODS: </strong>Genome-wide DNA methylation profiles in 14 AsUC and 14 non-AsUC were analyzed by Illumina Infinium methylation27 BeadChip and validated by bisulfite pyrosequencing. Mean methylation levels (?¯) in AsUC and non-AsUC were compared by their ratio (?¯ ratio) and difference (??¯). Associations between site-specific methylation levels in UC and cumulative arsenic exposure were examined.<br /><br /><strong>RESULTS: </strong>Among 27,578 methylation sites analyzed, 231 sites had ?¯ ratio >2 or <0.5 and 45 sites had ??¯ >0.2 or <-0.2. There were 13 sites showing statistically significant (q<0.05) differences in ?¯ between AsUC and non-AsUC including 12 hypermethylation sites in AsUC and only one hypermethylation site in non-AsUC. Significant associations between cumulative arsenic exposure and DNA methylation levels of 28 patients were observed in nine CpG sites of nine gens including PDGFD (Spearman rank correlation, 0.54), CTNNA2 (0.48), KCNK17 (0.52), PCDHB2 (0.57), ZNF132 (0.48), DCDC2 (0.48), KLK7 (0.48), FBXO39 (0.49), and NPY2R (0.45). These associations remained statistically significant for CpG sites in CTNNA2, KLK7, NPY2R, ZNF132 and KCNK17 in 20 non-smoking women after adjustment for tumor stage and age.<br /><br /><strong>CONCLUSIONS: </strong>Significant associations between cumulative arsenic exposure and methylation level of CTNNA2, KLK7, NPY2R, ZNF132 and KCNK17 were found in smoking-unrelated urothelial carcinoma. Arsenic exposure may cause urothelial carcinomas through the hypermethylation of genes involved in cell adhesion, proteolysis, transcriptional regulation, neuronal pathway, and ion transport. The findings of this study, which are limited by its small sample size and moderate dose-response relation, remain to be validated by further studies with large sample sizes.",
Arsenic,627555,"Bladder cancer mortality and private well use in New England: An ecological study Abstract: STUDY OBJECTIVE: To investigate the possible relation between bladder cancer mortality among white men and women and private water use in New England, USA, where rates have been persistently raised and use of private water supplies (wells) common. DESIGN: Ecological study relating age adjusted cancer mortality rates for white men and women during 1985-1999 and proportion of persons using private water supplies in 1970. After regressing mortality rates on population density, Pearson correlation coefficients were computed between residual rates and the proportion of the population using private water supplies, using the state economic area as the unit of calculation. Calculations were conducted within each of 10 US regions. SETTING: The 504 state economic areas of the contiguous United States. PARTICIPANTS: Mortality analysis of 11 cancer sites, with the focus on bladder cancer. MAIN RESULTS: After adjusting for the effect of population density, there was a statistically significant positive correlation between residual bladder cancer mortality rates and private water supply use among both men and women in New England (men, r = 0.42; women, r = 0.48) and New York/New Jersey (men, r = 0.49; women, r = 0.62). CONCLUSIONS: Use of well water from private sources, or a close correlate, may be an explanatory variable for the excess bladder cancer mortality in New England. Analytical studies are underway to clarify the relation between suspected water contaminants, particularly arsenic, and raised bladder cancer rates in northern New England.",
Arsenic,1239892,"Examination of the distribution of arsenic in hydrated and fresh cowpea roots using two- and three-dimensional techniques Abstract: Arsenic (As) is considered to be the environmental contaminant of greatest concern due to its potential accumulation in the food chain and in humans. Using novel synchrotron-based x-ray fluorescence techniques (including sequential computed tomography), short-term solution culture studies were used to examine the spatial distribution of As in hydrated and fresh roots of cowpea (Vigna unguiculata 'Red Caloona') seedlings exposed to 4 or 20 µm arsenate [As(V)] or 4 or 20 µm arsenite. For plants exposed to As(V), the highest concentrations were observed internally at the root apex (meristem), with As also accumulating in the root border cells and at the endodermis. When exposed to arsenite, the endodermis was again a site of accumulation, although no As was observed in border cells. For As(V), subsequent transfer of seedlings to an As-free solution resulted in a decrease in tissue As concentrations, but growth did not improve. These data suggest that, under our experimental conditions, the accumulation of As causes permanent damage to the meristem. In addition, we suggest that root border cells possibly contribute to the plant's ability to tolerate excess As(V) by accumulating high levels of As and limiting its movement into the root.",
Arsenic,1015693,"Ecotoxicological impacts of effluents generated by oil sands bitumen extraction and oil sands lixiviation on Pseudokirchneriella subcapitata Abstract: The exploitation of Athabasca oil sands deposits in northern Alberta has known an intense development in recent years. This development has raised concern about the ecotoxicological risk of such industrial activities adjacent to the Athabasca River. Indeed, bitumen extraction generated large amounts of oil sands process-affected water (OSPW) which are discharged in tailing ponds in the Athabasca River watershed. This study sought to evaluate and compare the toxicity of OSPW and oil sands lixiviate water (OSLW) with a baseline (oil sands exposed to water; OSW) on a microalgae, Pseudokirchneriella subcapitata, at different concentrations (1.9, 5.5, 12.25, 25 and 37.5%, v/v). Chemical analyses of water-soluble contaminants showed that OSPW and OSLW were enriched in different elements such as vanadium (enrichment factor, EF=66 and 12, respectively), aluminum (EF=64 and 15, respectively), iron (EF=52.5 and 17.1, respectively) and chromium (39 and 10, respectively). The toxicity of OSPW on cells with optimal intracellular esterase activity and chlorophyll autofluorescence (viable cells) (72h-IC 50%&lt;1.9%) was 20 times higher than the one of OSW (72h-IC 50%&gt;37.5%, v/v). OSLW was 4.4 times less toxic (IC 50%=8.5%, v/v) than OSPW and 4.5 times more toxic than OSW. The inhibition of viable cell growth was significantly and highly correlated (&lt;-0.7) with the increase of arsenic, beryllium, chromium, copper, lead, molybdenum and vanadium concentrations. The specific photosynthetic responses studied with JIP-test (rapid and polyphasic chlorophyll a fluorescence emission) showed a stimulation of the different functional parameters (efficiency of PSII to absorb energy from photons, size of effective PSII antenna and vitality of photosynthetic apparatus for energy conversion) in cultures exposed to OSPW and OSLW. To our knowledge, our study highlights the first evidence of physiological effects of OSPW and OSLW on microalgae.",
Arsenic,1022222,"Arsenic methylation by micro-organisms isolated from sheepskin bedding materials Abstract: Sudden infant death syndrome (SIDS) has been associated with the volatilization of arsenic, antimony or phosphorus compounds from infants' bedding material by micro-organisms, the so-called 'toxic gas hypothesis'. The volatilization of arsenic by aerobic micro-organisms isolated from new sheepskin bedding material, as well as on material used by a healthy infant and by an infant who perished of SIDS, was examined. Three fungi were isolated from a piece of sheepskin bedding material on which an infant perished of SIDS, which methylated arsenic to form trimethylarsenic(V) species, precursors to volatile trimethylarsine. These three fungi were identified as Scopulariopsis koningii, Fomitopsis pinicola and Penicillium gladioli by their 26S-ribosomal RNA polymerase chain reaction products. These fungi were not previously known to methylate arsenic. The volatilization of arsenic by these three fungi was then examined. Only P. gladioli volatilized arsenic and only under conditions such that the production of sufficient trimethylarsine to be acutely toxic to an infant is unlikely. S. brevicaulis grew on the sheepskin bedding material and evolved a trace amount of trimethylarsine. Known human pathogens such as Mycobacterium neoaurum and Acinetobacter junii were isolated from used bedding.",
Arsenic,1339190,"Arsenic exposure through drinking water Is associated with longer telomeres in peripheral blood Abstract: Inorganic arsenic is a strong carcinogen, possibly by interaction with the telomere length. The aim of the study was to evaluate how chronic arsenic exposure from drinking water as well as the arsenic metabolism efficiency affect the individual telomere length and the expression of telomere-related genes. Two hundred two women with a wide range in exposure to arsenic via drinking water (3.5-200 ?g/L) were recruited. Concentrations of arsenic metabolites in urine [inorganic arsenic (iAs), methylarsonic acid (MMA), and dimethylarsinic acid (DMA)] were measured. The relative telomere length in blood was measured by quantitative real-time polymerase chain reaction. Genotyping (N = 172) for eight SNPs in AS3MT and gene expression of telomere-related genes (in blood; N = 90) were performed. Urinary arsenic (sum of metabolites) was positively associated with telomere length (? = 0.65 × 10(-4), 95% CI = 0.031 × 10(-4)-1.3 × 10(-4), adjusted for age and BMI). Individuals with above median fractions of iAs and MMA showed significantly longer telomeres by increasing urinary arsenic (? = 1.0 × 10(-4), 95% CI = 0.21 × 10(-4)-1.8 × 10(-4) at high % iAs; ? = 0.88 × 10(-4) 95% CI = 0.12 × 10(-4)-1.6 × 10(-4) at high % MMA) than those below the median (p = 0.80 and 0.44, respectively). Similarly, carriers of the slow and more toxic metabolizing AS3MT haplotype showed stronger positive associations between arsenic exposure and telomere length, as compared to noncarriers (interaction urinary arsenic and haplotype p = 0.025). Urinary arsenic was positively correlated with the expression of telomerase reverse transcriptase (TERT, Spearman r = 0.22, p = 0.037), but no association was found between TERT expression and telomere length. Arsenic in drinking water influences the telomere length, and this may be a mechanism for its carcinogenicity. A faster and less toxic arsenic metabolism diminishes arsenic-related telomere elongation.",
Arsenic,1031609,"Arsenite inhibits beta-oxidation in isolated rat liver mitochondria Abstract: A partial inhibition of acylcarnitine oxidation by arsenite in rat liver mitochondria has been studied. This inhibition is confined to the thiolase(s). The inhibition was observed also in the presence of malate, indicating no selective effect on ketogenesis. Ketogenesis from acetyl-CoA was inhibited by arsenite. Mitochondrial CoA was acylated by acylcarnitine nearly as rapidly in the presence of arsenite as in its absence. Thus, arsenite did not interfere with the availibility of CoA in the mitochondria. No effect of arsenite on enzymes of beta-oxidation other than the thiolase(s) was observed. When arsenite and acylcarnitine were added simultaneously to mitochondria, there was a delay before maximal inhibition of oxygen uptake occurred. When the mitochondria were preincubated with arsenite before addition of acylcarnitine, the inhibitory effect on oxygen utilization was initially large, but then partially repealed. Similar time delays were observed in the activity of acetoacetyl-CoA thiolase of disrupted mitochondria depending on the sequence of arsenite and acetoacetyl-CoA addition. It is suggested that substrate and arsenite complete for the reactive sulfhydryl group at the active site of the thiolase(s).",
Arsenic,1025029,"Simultaneous determination of arsenic and selenium in biological samples by HG-AFS Abstract: A new method is proposed for simultaneous determination of traces of arsenic (As) and selenium (Se) in biological samples by hydride-generation double-channel non-dispersive atomic-fluorescence spectrometry (HG-AFS) from tartaric acid media. The effects of analytical conditions on fluorescence signal intensity were investigated and optimized. Interferences from coexisting ions were evaluated. Under optimum conditions linear response ranges above 20 microg L(-1) for As and 32 microg L(-1) for Se were obtained with detection limits of 0.13 and 0.12 microg L(-1), respectively. The precision for eleven-fold determination of As at the 4 microg L(-1) level and of Se at the 8 microg L(-1) level were 2.7 and 1.9% (RSD), respectively. Recoveries of 92.5-95.5% for As and 101.2-108.4% for Se were obtained for four biological samples and two certified biological reference materials. The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for simultaneous determination of As and Se in biological samples.",
Arsenic,1579243,"Apple peels - a versatile biomass for water purification? Abstract: The presence of anions such as chromate, arsenate and arsenite in drinking water is a major health concern in many parts of the world due to their high toxicity. Removal of such anions from water using low cost biomass is an efficient and affordable treatment process. Owing to the easy availability and biodegradability, we chose to use apple peel as a substrate for our investigations. Zirconium cations were immobilized onto the apple peel surface and used for the extraction of anions. Zirconium loaded apple peels were used to extract anions such as phosphate, arsenate, arsenite and chromate ions from aqueous solutions. The presence of Zr cations on apple peel surface was characterized using XPS. The modified adsorbent was characterized using SEM, EDS, and FT-IR. Zr treated apple peels showed efficient adsorption towards AsO2- (15.64 mg/g), AsO43- (15.68 mg/g), Cr2O72- (25.28 mg/g) and PO43- (20.35 mg/g) anions. The adsorption and desorption studies revealed the adsorption mechanism involves electrostatic interactions. Anion removal efficiency was estimated by batch adsorption studies. Adsorption kinetic parameters for all anions at different concentrations were described using pseudo-first-order and pseudo-second-order rate equation. Langumir and Freundlich isotherms were used to validate our adsorption data. Arsenate and chromate anions were strongly adsorbed at the pH range from 2 to 6, while arsenite was extracted efficiently between pH 9 and 10. Overall, the Zr immobilized apple peel is an efficient adsorbent for common anionic pollutants.",
Arsenic,1340061,"Late-onset increases in oxidative stress and other tumorigenic activities and tumors with a Ha-ras mutation in the liver of adult male C3H mice gestationally exposed to arsenic Abstract: Tumorigenesis is a complex process involving genetic, epigenetic, and metabolic alterations. Gestational arsenic exposure has been shown to increase hepatic tumors in adult male offspring of C3H mice, which spontaneously develop hepatic tumors often harboring activating Ha-ras mutation. We explored tumor-promoting changes by gestational arsenic exposure with a focus on Ha-ras mutation and gene expression changes. The results of this study demonstrated that gestational arsenic exposure particularly increased hepatic tumors with a C61A Ha-ras mutation. Real-time PCR analyses on the adult normal livers showed that two genes (Creld2, Slc25a30), whose expression are induced by endoplasmic reticulum stress and cellular oxidative stress, respectively, were significantly upregulated and two genes (Fabp4, Ell3), whose products are involved in lipid efflux and apoptosis, respectively, were significantly downregulated more than twofold by gestational arsenic exposure compared with control mice. The expression changes in the four genes were shown to be late-onset events and to some extent to be associated with corresponding histone modifications, and not with DNA methylation changes. The gene expression changes suggested alterations in lipid metabolism and associated oxidative stress augmentation. Consistently, expression of an oxidative-stress-inducible gene heme oxygenase-1 (HO-1) was upregulated in the livers of the arsenic group. We also found increased expression of retrotransposon L1 mRNA in the tumor-bearing livers of the arsenic group in comparison with control mice. These results suggested that gestational arsenic exposure induces tumor-augmenting changes, including oxidative stress and L1 activation, in a late-onset manner, which would particularly promote tumorigenic expansion of cells with a C61A Ha-ras mutation.",
Arsenic,710987,"Mathematical model of uptake and metabolism of arsenic(III) in human hepatocytes - Incorporation of cellular antioxidant response and threshold-dependent behavior Abstract: Arsenic is an environmental pollutant, potent human toxicant, and oxidative stress agent with a multiplicity of health effects associated with both acute and chronic exposures. A semi-mechanistic cellular-level toxicokinetic (TK) model was developed in order to describe the uptake, biotransformation and clearance of arsenical species in human hepatocytes. Notable features of this model are the incorporation of arsenic-glutathione complex formation and a &quot;switch-like&quot; formulation to describe the antioxidant response of hepatocytes to arsenic exposure.<br /><br /> The cellular-level TK model applies mass action kinetics in order to predict the concentrations of trivalent and pentavalent arsenicals in hepatocytes. The model simulates uptake of arsenite (iAsIII) via aquaporin isozymes 9 (AQP9s), glutathione (GSH) conjugation, methylation by arsenic methyltransferase (AS3MT), efflux through multidrug resistant proteins (MRPs) and the induced antioxidant response via thioredoxin reductase (TR) activity. The model was parameterized by optimization of model estimates for arsenite (iAsIII), monomethylated (MMA) and dimethylated (DMA) arsenicals concentrations with time-course experimental data in human hepatocytes for a time span of 48 hours, and dose-response data at 24 hours for a range of arsenite concentrations from 0.1 to 10 ?M. Global sensitivity analysis of the model showed that at low doses the transport parameters had a dominant role, whereas at higher doses the biotransformation parameters were the most significant. A parametric comparison of the TK model with an analogous model developed for rat hepatocytes from the literature demonstrated that the biotransformation of arsenite (e.g. GSH conjugation) has a large role in explaining the variation in methylation between rats and humans.<br /><br /> The cellular-level TK model captures the temporal modes of arsenical accumulation in human hepatocytes. It highlighted the key biological processes that influence arsenic metabolism by explicitly modelling the metabolic network of GSH-adducts formation. The parametric comparison with the TK model developed for rats suggests that the variability in GSH conjugation could have an important role in inter-species variability of arsenical methylation. The TK model can be incorporated into larger-scale physiologically based toxicokinetic (PBTK) models of arsenic for improving the estimates of PBTK model parameters.",
Arsenic,1339132,"Mortality in young adults following in utero and childhood exposure to arsenic in drinking water Abstract: Background: Beginning in 1958, the city of Antofagasta in northern Chile was exposed to high arsenic concentrations (870 µg/L) when it switched water sources. The exposure abruptly stopped in 1970 when an arsenic-removal plant commenced operations. A unique exposure scenario like this-with an abrupt start, clear end, and large population (125,000 in 1970), all with essentially the same exposure-is rare in environmental epidemiology. Evidence of increased mortality from lung cancer, bronchiectasis, myocardial infarction, and kidney cancer has been reported among young adults who were in utero or children during the high-exposure period.Objective: We investigated other causes of mortality in Antofagasta among 30- to 49-year-old adults who were in utero or ? 18 years of age during the high-exposure period.Methods: We compared mortality data between Antofagasta and the rest of Chile for people 30-49 years of age during 1989-2000. We estimated expected deaths from mortality rates in all of Chile, excluding Region II where Antofagasta is located, and calculated standardized mortality ratios (SMRs).Results: We found evidence of increased mortality from bladder cancer [SMR = 18.1; 95% confidence interval (CI): 11.3, 27.4], laryngeal cancer (SMR = 8.1; 95% CI: 3.5, 16.0), liver cancer (SMR = 2.5; 95% CI: 1.6, 3.7), and chronic renal disease (SMR = 2.0; 95% CI: 1.5, 2.8).Conclusions: Taking together our findings in the present study and previous evidence of increased mortality from other causes of death, we conclude that arsenic in Antofagasta drinking water has resulted in the greatest increases in mortality in adults &lt; 50 years of age ever associated with early-life environmental exposure.",
Arsenic,1704103,Modeling Approaches of Competitive Sorption and Transport of Trace Metals and Metalloids in Soils: A Review Abstract: ,
Arsenic,2278902,"Oxidation of organosulfur-coordinated arsenic and realgar in peat: Implications for the fate of arsenic Abstract: Organosulfur-coordinated As(III) and realgar (?-As4S4) have been identified as the dominant As species in the naturally As-enriched minerotrophic peatland Gola di Lago, Switzerland. In this study, we explored their oxidation kinetics in peat exposed to atmospheric O2 for up to 180 days under sterile and nonsterile conditions (25 °C, ?100% relative humidity). Anoxic peat samples were collected from a near-surface (0-38 cm) and a deep peat layer (200-250 cm) and studied by bulk As, Fe, and S K-edge X-ray absorption spectroscopy as well as selective extractions as a function of time. Over 180 days, only up to 33% of organosulfur-coordinated As(III) and 44% of realgar were oxidized, corresponding to half-life times, t1/2, of 312 and 215 days, respectively. The oxidation of both As species was mainly controlled by abiotic processes. Realgar was oxidized orders of magnitude slower than predicted from published mixed-flow reactor experiments, indicating that mass-transfer processes were rate-limiting. Most of the As released (&gt;97%) was sequestered by Fe(III)-(hydr)oxides. However, water-extractable As reached concentrations of 0.7-19 ?mol As L(-1), exceeding the WHO drinking water limit by up to 145 times. Only a fraction (20-36%) of reduced S(-II to I) was sensitive to oxidation and was oxidized faster (t1/2 = 50-173 days) than organosulfur-coordinated As(III) and realgar, suggesting a rapid loss of reactive As-sequestering S species following a drop in the water table. Our results imply that wetlands like Gola di Lago can serve as long-term sources for As under prolonged oxidizing conditions. The maintenance of reducing conditions is thus regarded as the primary strategy in the management of this and other As-rich peatlands.",
Arsenic,735044,"Modulation of DNA polymerase beta-dependent base excision repair in cultured human cells after low dose exposure to arsenite Abstract: Base excision repair (BER) is crucial for development and for the repair of endogenous DNA damage. However, unlike nucleotide excision repair, the regulation of BER is not well understood. Arsenic, a well-established human carcinogen, is known to produce oxidative DNA damage, which is repaired primarily by BER, whilst high doses of arsenic can also inhibit DNA repair. However, the mechanism of repair inhibition by arsenic and the steps inhibited are not well defined. To address this question we have investigated the regulation of DNA polymerase beta (Pol beta) and AP endonuclease (APE1), in response to low, physiologically relevant doses of arsenic. GM847 lung fibroblasts and HaCaT keratinocytes were exposed to sodium arsenite, As(III), and mRNA, protein levels and BER activity were assessed. Both Pol beta and APE1 mRNA exhibited significant dose-dependant down regulation at doses of As(III) above 1 microM. However, at lower doses Pol beta mRNA and protein levels, and consequently, BER activity were significantly increased. In contrast, APE1 protein levels were only marginally increased by low doses of As(III) and there was no correlation between APE1 and overall BER activity. Enzyme supplementation of nuclear extracts confirmed that Pol beta was rate limiting. These changes in BER correlated with overall protection against sunlight UV-induced toxicity at low doses of As(III) and produced synergistic toxicity at high doses. The results provide evidence that changes in BER due to low doses of arsenic could contribute to a non-linear, threshold dose response for arsenic carcinogenesis.",
Arsenic,2088548,"A Conserved Protein with AN1 Zinc-finger and Ubiquitin-like Domains Modulates Cdc48 (p97) Function in the Ubiquitin-Proteasome Pathway Abstract: Regulated protein degradation mediated by the ubiquitin-proteasome system (UPS) is critical to eukaryotic protein homeostasis. Often vital to degradation of protein substrates is their disassembly, unfolding, or extraction from membranes. These processes are catalyzed by the conserved AAA-ATPase Cdc48 (also known as p97). Here we characterize the Cuz1 protein (Cdc48-associated UBL/zinc-finger protein-1), encoded by a previously uncharacterized arsenite-inducible gene in budding yeast. Cuz1, like its human ortholog ZFAND1, has both an AN1-type zinc finger (Zf_AN1) and a divergent ubiquitin-like domain (UBL). We show that Cuz1 modulates Cdc48 function in the UPS. The two proteins directly interact, and the Cuz1 UBL, but not Zf_AN1, is necessary for binding to the Cdc48 N-terminal domain. Cuz1 also associates, albeit more weakly, with the proteasome, and the UBL is dispensable for this interaction. Cuz1-proteasome interaction is strongly enhanced by exposure of cells to the environmental toxin arsenite, and in a proteasome mutant, loss of Cuz1 enhances arsenite sensitivity. Whereas loss of Cuz1 alone causes only minor UPS degradation defects, its combination with mutations in the Cdc48(Npl4-Ufd1) complex leads to substantial further impairment. Cuz1 helps limit the accumulation of ubiquitin conjugates on both the proteasome and Cdc48, suggesting a possible role in the transfer of ubiquitylated substrates from Cdc48 to the proteasome or in their release from these complexes.",
Arsenic,1248971,"Differential effects of arsenic on calcium signaling in primary keratinocytes and malignant (HSC-1) cells Abstract: Arsenic is highly toxic to living cells, especially skin, and skin cancer is induced by drinking water containing arsenic. The molecular mechanisms of arsenic-induced cancer, however, are not well understood. To examine the initial processes in the development of arsenic-induced cancer, we analyzed calcium signaling at an early stage of arsenic treatment of human primary cells and compared the effects with those observed with arsenic treatment in carcinoma-derived cells. We found that arsenic inhibited inositol trisphosphate receptor (IP3R) function in the endoplasmic reticulum by inducing phosphorylation, which led to decreased intracellular calcium levels. Blockade of IP3R phosphorylation by the serine/threonine protein kinase Akt inhibitor wortmannin rescued calcium signaling. In contrast, arsenic treatment of cells derived from a carcinoma (human squamous carcinoma; HSC-1) for 1h had no obvious effect. Taken together, these results suggest that arsenic-induced reduction in calcium signaling is one of the initial mechanisms underlying the malignant transformation in the development of skin cancer.",
Arsenic,617372,"As2O3 toxicity in rat hepatocytes: manifestation of caspase-mediated apoptosis Abstract: In India, arsenic contamination in ground water is of immediate environmental concern affecting a large number of inhabitants in Kolkata. Arsenic is known to be one of the most toxic metalloids naturally occurring in the environment giving rise to severe toxic manifestations including cancer. Because arsenic is also used in chemotherapy of leukemia, it was considered worthwhile to concentrate on the mechanism of toxic action in normal hepatocytes which has not been addressed earlier. Rat hepatocytes were isolated and incubated in As2O3 at concentrations of 10, 20, and 40 ÃŽÂ¼M in a time-dependent manner (0, 15, 30 min and 1, 2, and 4 h). The expression of the common stress proteins HSP 70 and 90 throughout the experimental duration confirmed the magnitude of toxic effect imposed by arsenic. Microscopic observations showed clear apoptotic changes in hepatocytes, which were further characterized by DNA ladder formation in time- and concentration-dependent manners. Apoptosis was triggered by caspase activation and over expression of bax at 10 ÃŽÂ¼MAs2O3 and at 20 and 40 ÃŽÂ¼M concentrations of As2O3, MAP kinases were found to mediate the apoptotic pathway. Co-treatment of cells with arsenic and caspase inhibitor (Ac-DEVD-Cho) led to over expression of bcl-2, suppression of bax, and cytosolic sequestration of Bid and Bad. It is therefore concluded that caspase activation has a direct role in arsenic-induced apoptosis mediated by mitochondrial factors at 10 ÃŽÂ¼M As2O3, and JUN N-terminal kinase (JNK) and P38 activation are the major mediators of apoptosis at the higher test concentrations (20 and 40 ÃŽÂ¼M) of As2O3. [ABSTRACT FROM AUTHOR] Copyright of Toxicology & Industrial Health is the property of Sage Publications, Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)",
Arsenic,1033333,"A validation of questionnaire information on occupational exposure and smoking Abstract: Occupational exposure information obtained via a questionnaire to close relatives of 160 deceased smelter workers was compared with data from employee registers. The data from the questionnaire regarding employment at the smelter had a very high validity, ie, a sensitivity of 98% and a specificity of 99%. When an assessment of arsenic exposure was made from information in the questionnaire, the sensitivity was only 40%, but the specificity was over 90%. Data on smoking habits were available from medical files for only 14 of the subjects. For all 14, the information was identical to the data in the questionnaires. It appears that questionnaires may sometimes be of use for exposure assessments in occupational health epidemiology.",
Arsenic,1579308,"Baseline comorbidities in a skin cancer prevention trial in Bangladesh Abstract: BACKGROUND: Epidemiologic research suggests that increased cancer risk due to chronic arsenic exposure persists for several decades even after the exposure has terminated. Observational studies suggest that antioxidants exert a protective effect on arsenical skin lesions and cancers among those chronically exposed to arsenic through drinking water. This study reports on the design, methods and baseline analyses from the Bangladesh Vitamin E and Selenium Trial (BEST), a population-based chemoprevention study conducted among adults in Bangladesh with visible arsenic toxicity. MATERIALS AND METHODS: Bangladesh Vitamin E and Selenium Trial is a 2×2 full factorial, double-blind, randomized controlled trial of 7000 adults having manifest arsenical skin lesions evaluating the efficacy of 6-year supplementation with alpha-tocopherol (100 mg daily) and L-selenomethionine (200 ?g daily) for the prevention of nonmelanoma skin cancer. RESULTS: In cross-sectional analyses, we observed significant associations of skin lesion severity with male gender (female prevalence odds ratio (POR) = 0·87; 95% CI = 0·79-0·96), older age (aged 36-45 years, POR = 1·27; 95% CI = 1·13-1·42; aged 46-55 years, POR = 1·44; 95% CI = 1·27-1·64 and aged 56-65 years, POR = 1·50; 95% CI = 1·26-1·78 compared with aged 25-35 years), hypertension (POR = 1·29; 95% CI = 1·08-1·55), diabetes (POR = 2·13; 95% CI = 1·32-3·46), asthma (POR = 1·55; 95% CI = 1·03-2·32) and peptic ulcer disease (POR = 1·20; 95% CI = 1·07-1·35). CONCLUSIONS: We report novel associations between arsenical skin lesions with several common chronic diseases. With the rapidly increasing burden of preventable cancers in developing countries, efficient and feasible chemoprevention study designs and approaches, such as employed in BEST, may prove both timely and potentially beneficial in conceiving cancer chemoprevention trials in Bangladesh and beyond.",
Arsenic,1508556,"New clues to the local atomic structure of short-range ordered ferric arsenate from EXAFS spectroscopy Abstract: Short-range ordered ferric arsenate (FeAsO(4)•xH(2)O) is a secondary As mineral frequently encountered in acid mine-waste environments. Two distinct structural models have recently been proposed for this phase. The first model is based on the structure of scorodite (FeAsO(4)•2H(2)O) where isolated FeO(6) octahedra share corners with four adjacent arsenate (AsO(4)) tetrahedra in a three-dimensional framework (framework model). The second model consists of single chains of corner-sharing FeO(6) octahedra being bridged by AsO(4) bound in a monodentate binuclear (2)C complex (chain model). In order to rigorously test the accuracy of both structural models, we synthesized ferric arsenates and analyzed their local (&lt;6 Å) structure by As and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. We found that both As and Fe K-edge EXAFS spectra were most compatible with isolated FeO(6) octahedra being bridged by AsO(4) tetrahedra (R(Fe-As) = 3.33 ± 0.01 Å). Our shell-fit results further indicated a lack of evidence for single corner-sharing FeO(6) linkages in ferric arsenate. Wavelet-transform analyses of the Fe K-edge EXAFS spectra of ferric arsenates complemented by shell fitting confirmed Fe atoms at an average distance of ~5.3 Å, consistent with crystallographic data of scorodite and in disagreement with the chain model. A scorodite-type local structure of short-range ordered ferric arsenates provides a plausible explanation for their rapid transformation into scorodite in acid mining environments.",
Arsenic,627094,"MRP-1 expression levels determine strain-specific susceptibility to sodium arsenic-induced renal injury between C57BL/6 and BALB/c mice Abstract: To clarify the pathophysiological mechanism underlying acute renal injury caused by acute exposure to arsenic, we subcutaneously injected both BALB/c and C57BL/6 mice with sodium arsenite (NaAs; 13.5 mg/kg). BALB/c mice exhibited exaggerated elevation of serum blood urea nitrogen (BUN) and creatinine (CRE) levels, compared with C57BL/6 mice. Moreover, half of BALB/c mice died by 24 h, whereas all C57BL/6 mice survived. Histopathological examination on kidney revealed severe hemorrhages, acute tubular necrosis, neutrophil infiltration, cast formation, and disappearance of PAS-positive brush borders in BALB/c mice, later than 10 h. These pathological changes were remarkably attenuated in C57BL/6 mice, accompanied with lower intrarenal arsenic concentrations, compared with BALB/c mice. Among heavy metal inducible proteins including multidrug resistance-associated protein (MRP)-1, multidrug resistance gene (MDR)- 1, metallothionein (MT)-1, and arsenite inducible, cysteine- and histidine-rich RNA-associated protein (AIRAP), intrarenal MDR-1, MT-1, and AIRAP gene expression was enhanced to a similar extent in both strains, whereas NaAs challenge augmented intrarenal MRP-1 mRNA and protein expression levels in C57BL/6 but not BALB/c mice. Moreover, the administration of a specific inhibitor of MRP-1, MK-571, significantly exaggerated acute renal injury in C57BL/6 mice. Thus, MRP-1 is crucially involved in arsenic efflux and eventually prevention of acute renal injury upon acute exposure to NaAs.",
Arsenic,1794826,Arsenomics of Exiguobacterium sp PS (NCIM 5463) Abstract: ,
Arsenic,2337086,"Biogeochemistry of heavy metals in contaminated excessively moistened soils (Analytical review) Abstract: The biogeochemical behavior of heavy metals in contaminated excessively moistened soils depends on the development of reducing conditions (either moderate or strong). Upon the moderate biogenic reduction, Cr as the metal with variable valence forms low-soluble compounds, which decreases its availability to plants and prevents its penetration into surface- and groundwater. Creation of artificial barriers for Cr fixation on contaminated sites is based on the stimulation of natural metal-reducing bacteria. Arsenic, being a metalloid with a variable valence, is mobilized upon the moderate biogenic reduction. The mobility of siderophilic heavy metals with a constant valence grows under the moderate reducing conditions at the expense of dissolution of iron (hydr)oxides as carriers of these metals. Zinc, which can enter the newly formed goethite lattice, is an exception. Strong reduction processes in organic excessively moist and flooded soils (usually enriched in S) lead to the formation of low-soluble sulfides of heavy elements with both variable (As) and constant (Cu, Ni, Zn, and Pb) valence. On changing aquatic regime in overmoistened soils and their drying, sulfides of heavy metals are oxidized, and previously fixed metals are mobilized.",
Arsenic,2343524,"Metal leaching, acidity, and altitude confine benthic macroinvertebrate community composition in Andean streams Abstract: Andean streams drain metal-rich bedrock and are subjected to an extreme altitude gradient, which may create highly selective conditions for life. The aim of the present study was to evaluate the combined effects of metals and altitude on benthic macroinvertebrate community composition in Andean streams. Metal-rich sites were characterized by high metal concentrations and low pH, and high-altitude sites were characterized by high ultraviolet-B radiation and low concentrations of dissolved organic matter. Canonical correspondence analysis indicated that the patterns in faunal composition were best explained by metals followed by altitude, with dipterans and collembolans occurring mostly under harsh conditions of high altitude and high metal levels. Interaction between metals and altitude was most evident at metal-rich sites. It is suggested that in Andean streams, metal leaching from igneous rock and altitude may be important factors confining benthic macroinvertebrate communities, reducing their numbers and changing their composition toward specialized taxa.",
Arsenic,1936120,"Experimental approaches for the estimation of uncertainty in analysis of trace inorganic contaminants in foodstuffs by ICP-MS Abstract: Total Diet Studies to estimate dietary exposure to food contaminants need to evaluate laboratory measurements data variance. In this process it is critical that data from analytical methods are reliable to correctly scrutinize and compare values over time and between countries. In Europe it is widely recognized that the evaluation of measurement uncertainty is an important parameter when assessing the sources of analytical data variability. Two approaches are considered to estimate uncertainty in analytical measurement. Arsenic, Lead, Chromium and Cadmium, content in several food matrix determined by Inductively Coupled Mass Spectrometry (ICP-MS) microwave digestion assisted, are used as examples. The aim of the present research work is to compare both approaches accepted by Eurolab and GUM: Mathematical modeling to assess uncertainty components based on a classical model (bottom up) and an empirical method (top down), based on either experimental data obtained from a single laboratory validation data or inter-laboratory data from Proficiency Testing schemes. Relative expanded uncertainty calculated by both approaches agree when U (%) <20%. These values are concordant with RSDR reported in collaborative studies of EN 15763 (2009), which were assumed as target uncertainty. The top down approach described is simple and easy to use when compared with the mathematical modeling approach providing considerable benefits to those who assess data produced by several laboratories.",
Arsenic,1016012,"Validation of analysis of arsenic in water samples using Wagtech Digital Arsenator Abstract: Groundwater, the only source of potable water for millions of people in Bangladesh during dry season, is often contaminated with arsenic (As) above the allowable drinking water limit of 50 ?g/L. Testing well water--with arsenic field test kits (FTKs)--and switching to safe-wells can effectively reduce exposure to As. FTKs are low cost, provide fast results, and are commercially available. There are between 10 and 11 million shallow tubewells in Bangladesh. Approximately, 5 million have been tested using FTKs. FTKs with color comparator rely on visual identification for generating qualitative results, which may not be highly reliable at the lower range because human eyes have low sensitivity in this range and sensitivity varies from person to person. The Wagtech Digital Arsenator does not suffer from this limitation and should, in theory, be able to generate quantitative, accurate, and reliable results. The instrument has a linear range of 0-100 ?g/L, an accuracy of ± 20% for the 50 ?g/L quality control standards, and a detection limit of about 4.4 ?g/L. All Arsenators employed in this investigation also displayed high bias for 50 ?g/L arsenic standard and were calibrated in order to improve measurement accuracy and reliability. Analyses of 179 raw and 92 treated well waters in the field and in two analytical laboratories were found to be highly correlated with the Spearman rank correlation coefficient of ? 0.800, indicating that Arsenator results are perhaps nearly as accurate and reliable as those from analytical laboratories.",
Arsenic,2088553,"Ameliorative effect of diallyl trisulphide on arsenic-induced oxidative stress in rat erythrocytes and DNA damage in lymphocytes Abstract: Background: Arsenic (As) is a naturally occurring semimetallic element that is classified as a toxicant and a human carcinogen. Diallyl trisulphide (DATS), an organosulphur compound, is an antioxidative substance that is extracted from garlic (Allium sativum). Erythrocytes are very expedient models to understand the susceptibility of membrane to oxidative damage induced by different xenobiotic compounds. Arsenic has been reported to induce oxidative stress to erythrocytes due to lipid peroxidation and alteration in defence mechanism as erythrocytes are the first target that arsenic compounds attack in the body after systemic absorption. In the light of this fact, the purpose of this study is to characterise the ameliorative effect of DATS on arsenic-induced oxidative stress in rat erythrocytes. Methods: Experimental rats were randomly divided into four groups and treated orally for 28 days: control, As [5 mg/kg body weight (BW)] treated, As+DATS (80 mg/kg BW) treated, DATS (80 mg/kg BW) treated and As+vitamin C (100 mg/kg BW) treated. Oxidative stress in erythrocytes was recorded by estimating plasma marker enzymes, plasma and erythrocyte membrane oxidative stress markers, erythrocyte membrane antioxidant enzymes and non-antioxidant enzymes, etc. Results: Oral administration of arsenic at 5 mg/kg BW per day elevated the levels of plasma marker enzymes, namely, aspartate transaminase (AST), alanine transaminase (ALT), acid phosphatase (ACP), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and ?-glutamyl transferase (?GT) (U/L) with significantly increased lipid peroxidation markers such as thiobarbituric acid reactive substances (TBARS), malondialdehyde (MDA), lipid hydroperoxides (LH), conjugated dienes (CD), and protein carbonyl (PC) contents were also elevated in As-treated rat plasma and erythrocytes. The levels of non-enzymatic antioxidants (reduced glutathione, vitamins C and E) and enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), and glucose-6-phosphate dehydrogenase (G6PD) were also decreased in As-treated rats. The toxic effect of As significantly decreased the activities of membrane-bound ATPases (Na+/K+-ATPase, Mg2+-ATPase, and Ca2+-ATPase), with a significant increase in% tail DNA of rat lymphocytes measured by means of a single-cell gel electrophoresis assay. Administration of DATS for 28 days significantly reduced the levels of plasma markers. The levels of TBARS, MDA, LH, CD, and PC were significantly decreased and there was a significant increase in ATPase activities and non-enzymatic and enzymatic antioxidants on treatment with DATS in a dose-related manner. Conclusions: All these changes were supported by reduction of DNA damage in lymphocytes with DATS treatment. DATS at a dose of 80 mg/kg BW was found to be most effective and the results revealed the same. The results of the study showed that DATS shows a protective effect against As-induced oxidative stress in rat erythrocytes and lymphocytes.",
Arsenic,1509325,Iron plaque formation and its effect on arsenic uptake by different genotypes of paddy rice Abstract: ,
Arsenic,1788948,"Availability of geogenic heavy metals in soils of Thiva town (central Greece) Abstract: Potentially toxic metals in the urban chemical environment impose risks to both ecosystem and human health. Here, we evaluate the labile pools and availabilities of non-anthropogenic Ni, Cr, Co and Mn in soil samples from Thiva town (central Greece) and investigate their associations with common soil properties and geochemical data obtained by the aqua regia and single selective dissolutions. Experimental work included the initial application of the sequential extraction protocol proposed by the European Community Bureau of Reference and chemical extractions with ethylenediamine tetraacetic acid solution and a modified physiologically based extraction test with the aim to obtain the operationally defined fractions of plant availability and human bioaccessibility, respectively. The leachate results demonstrated that despite the significant contribution of residual metal species especially for Ni and Cr, the studied serpentine soils provide chemically labile pools for all the considered elements. Nickel was found to be the most available metal with the order being Ni?&gt;?Cr???Co???Mn for plant uptake and Ni?&gt;?Cr?&gt;?Co???Mn for human bioaccessibility. The aqua regia extractable concentrations are not predictors of elemental availabilities except for Ni bioaccessible data interpreting however only a moderate percentage of the total variance. The incorporation of basic soil properties (mostly total organic carbon), geochemical data for the major elements Ca, Mg and Fe and ammonium oxalate extractable Cr significantly improved the estimations for individual elements entailing the strong influence of the chemistry and mineralogy of soil materials to the release of focus metals from the soil matrix. This study provides for the first time bioaccessible data for serpentine-derived soils that are more realistic for evaluating potential adverse effects on the human health.",
Arsenic,628794,"Possible beneficial effects of melatonin supplementation on arsenic-induced oxidative stress in Wistar rats Abstract: The effects of melatonin on arsenic-induced changes on cellular antioxidant system were studied in male rats of the Wistar strain. Arsenic treatment (i.p. as sodium arsenite) was done at a dose of 5.55 mg/kg body weight (equivalent to 35% of LD50) per day for a period of 30 days, while melatonin supplementation (i.p.) was performed at a dose of 10 mg/kg body weight per day for the last 5 days prior to sacrifice. Melatonin supplementation reversed the arsenic-mediated changes in reduced glutathione (GSH) level and lipid peroxidation in liver and kidney. Arsenic-induced decreased glutathione reductase activity in liver and increased activity in kidney was appreciably counteracted by melatonin. Melatonin also inhibited arsenic-induced free hydroxyl radical production in the tissues. The decreased superoxide dismutase (SOD) activity in liver and kidney and that of catalase in liver due to arsenic treatment were also counteracted by melatonin. It is suggested that melatonin acts as a protective agent against arsenic-induced cellular oxidative stress.",
Arsenic,628506,"Trivalent arsenicals induce lipid peroxidation, protein carbonylation, and oxidative DNA damage in human urothelial cells Abstract: Drinking arsenic-contaminated water is associated with an increased risk of bladder cancer. Arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonous acid (MMA(III)), monomethylarsonic acid (MMA(V)), dimethylarsinous acid (DMA(III)), and dimethylarsinic acid (DMA(V)) have all been detected in the urine of people who drink arsenic-contaminated water. The aim of this research was to investigate which of these arsenicals are more hazardous to human urothelial cells. The results indicate that iAs(III), MMA(III), and DMA(III) were more potent in inducing cytotoxicity, lipid peroxidation, protein carbonylation, oxidative DNA damage, nitric oxide, superoxide, hydrogen peroxide, and cellular free iron than MMA(V), DMA(V), and iAs(V) in human urothelial carcinoma and transformed cells. However, the results did not show convincingly that the trivalent arsenicals were more potent than pentavalent arsenicals in decreasing the intracellular contents of total thiol, protein thiol, and reduced glutathione. Induction of oxidative DNA damage was observed with 0.2 microM of iAs(III), MMA(III), or DMA(III) as early as 1h. Because of its high oxidative damage, higher proportion in urine, and lower cytotoxicity, DMA(III) may be the most hazardous arsenical to human urothelial cells.",
Arsenic,627513,"Effects of arsenic exposure among semiconductor workers: A cautionary note on urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine Abstract: Arsenic is a notorious environmental toxicant and was found to cause oxidative stress in cultured cells and animals. However, little work has been done in human studies, especially for the population occupationally exposed to arsenic. In order to investigate the effect of occupational exposure to arsenic in oxidative stress, we measured urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) from 90 semiconductor workers including 50 exposed and 40 nonexposed subjects. A highly sensitive and specific isotope dilution LC-MS/MS method was used for quantification of 8-oxodGuo. The levels of inorganic arsenic (iAs3+, iAs5+), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in urine were determined by high-performance liquid chromatography-flow injection atomic absorption spectrometry (HPLC-FIAAS). Results showed that the mean urinary concentrations of total arsenic and 8-oxodGuo were significantly higher for exposed workers compared with the nonexposed workers. In addition, elevated urinary 8-oxodGuo concentrations of exposed workers were correlated with urinary levels of MMA (r = 0.44, P < 0.005) and the extent of primary methylation (the ratio of MMA to inorganic arsenic) (r = 0.40, P < 0.005). These findings suggested that occupational exposure to arsenic could result in the induction of oxidative stress. The presence and/or formation of MMA could play an important role in arsenic-involved injuries.",
Arsenic,710103,"Hair analysis: Exploring the state of the science Abstract: On 12-13 June 2001, the Agency for Toxic Substances and Disease Registry (ATSDR) convened a seven-member panel in Atlanta, Georgia, to review and discuss the current state of the science related to hair analysis, specifically its use in assessing environmental exposures in support of the agency's public health assessment activities. ATSDR invited scientific experts in the fields of hair analysis, toxicology, and medicine to participate in a discussion of such topics as analytical methods, factors affecting the interpretation of analytical results, toxicologic considerations, and data gaps and research needs. The goal of the panel was to determine the overall utility of hair analysis as a tool to evaluate exposure at hazardous waste sites. The principal lesson learned from the meeting was that, for most substances, data are insufficient to predict health effects from the concentration of the substance in hair. The presence of a substance in hair may indicate exposure (both internal and external) but does not necessarily indicate the source of exposure. Thus, before hair analysis can be considered a valid tool for assessing exposure and health impact of a particular substance, research is needed to establish standardized reference ranges, gain a better understanding of biologic variations of hair growth with age, gender, race and ethnicity, and pharmacokinetics, and further explore possible dose-response relationships. ATSDR intends to use the findings of this panel to develop educational materials to support its site work and to encourage researchers to continue to develop methods that may facilitate reliable exposure assessments.",
Arsenic,735049,"Arsenic promotes centrosome abnormalities and cell colony formation in p53 compromised human lung cells Abstract: Epidemiological evidence indicated that residents, especially cigarette smokers, in arseniasis areas had significantly higher lung cancer risk than those living in non-arseniasis areas. Thus, an interaction between arsenic and cigarette smoking in lung carcinogenesis was suspected. p53 dysfunction or mutation in lung epithelial cells was frequently observed in cigarette smokers. Our present study was to explore the differential effects by arsenic on H1355 cells (human lung adenocarcinoma cell line with mutation in p53), BEAS-2B (immortalized lung epithelial cell with functional p53) and pifithrin-?-treated BEAS-2B cells (p53-inhibited cells). These cells were treated with different doses of sodium arsenite (0, 0.1, 1, 5 and 10 ?M) for 48 h. A greater reduction in cell viability was observed in the BEAS-2B cells vs. p53 compromised cells (H1355 or p53-inhibited BEAS-2B). Similar observation was also made on 7-day cell survival (growth) study. TUNEL analysis confirmed that there was indeed a significantly reduced arsenite-induced apoptosis found in p53-compromised cells. Centrosomal abnormality has been attributed to eventual chromosomal missegregation, aneuploidy and tumorigenesis. In our present study, reduced p21 and Gadd45a expressions and increased centrosomal abnormality (atopic and multiple centrosomes) were observed in both arsenite-treated H1355 and p53-inhibited BEAS-2B cells as compared with similarly treated BEAS-2B cells. Increased anchorage-independent growth (colony formation) of BEAS-2B cells co-treated with pifithrin-? and 5 ?M sodium arsenite was also observed in soft agar. Our present investigation demonstrated that arsenic would act specifically on p53 compromised cells (either with p53 dysfunction or inhibited) to induce centrosomal abnormality and colony formation. These findings provided strong evidence on the carcinogenic promotional role of arsenic, especially under the condition of p53 dysfunction.",
Arsenic,1021226,"Evaluation of in vivo acute immunotoxicity of a major organic arsenic compound arsenobetaine in seafood Abstract: In this study, we observed the in vivo acute immunotoxicity of a trimethyl arsenic compound, arsenobetaine (AsBe), which is present in large quantities in various marine animals that are daily ingested as seafood in many countries. The synthetic pure AsBe was orally administered to CDF(1) mice at a dose of 1.625 g/kg mouse weight once a day on days -6, -4, -2 and 0 (four times, total 6.5 g/kg mouse weight), and its effect on the immune organs and immune effector cells were assessed until day 8. Orally administered AsBe was temporally distributed to the immune organs, such as the spleen and thymus, but was not very toxic both quantitatively and qualitatively on these immune organs and immune effector cells, splenocytes, thymocytes, Peyer's patch lymphocytes and peritoneal macrophages. This finding suggests that the ingestion of AsBe contained in marine animals is relatively safe to the health of people who often consume marine animals in their daily diet.",
Arsenic,1335794,"Residential health study of families living near the Drake Chemical Superfund site in Lock Haven, Pennsylvania Abstract: The Pennsylvania Department of Health conducted a health survey of a group of residents in the Lock Haven area who live in the immediate vicinity of the Drake Superfund site. A control group of residents were selected randomly from the remaining areas of Lock Haven. The study did not indicate the presence of any serious chronic health conditions in the exposed group of residents when compared with the control group. Significantly more individuals in the exposed group than the control group experienced skin problems and sleepiness for at least 1 month prior to the survey, indicative of a possible association between direct human exposure to toxic chemicals from the site and the manifestation of symptoms. The increased prevalence of the two symptoms may also have been caused by factors other than contaminants at the Drake site, e.g., stress, occupational exposure, or other etiologic agents, or it may be a spurious finding due to chance or biased reporting.",
Arsenic,1327390,"Arsenite-induced germline apoptosis through a MAPK-dependent, p53-independent pathway in Caenorhabditis elegans Abstract: Many studies have shown that arsenite is a potent inducer of apoptosis both in cells and tissues. However, there is a lack of appropriate in vivo animal models to study the underlying mechanisms of arsenite-induced apoptosis. Caenorhabditis elegans is an excellent model organism for studying many biological processes. We showed previously that C. elegans could be used as an in vivo system to investigate the genotoxic effects of arsenite. In order to elucidate the underlying mechanisms of arsenite-induced apoptosis in vivo, in the present study, we used the mutated alleles of the C. elegans homologue of known mammalian genes that are involved in the regulation of apoptosis. Our results showed that the loss-of-function mutations of p53/ cep-1 and DNA damage response (DDR) genes hus-1, clk-2, and egl-1 exhibited significant increase in germline apoptosis under arsenite exposure, whereas arsenite-induced germline apoptosis was blocked in loss-of-function alleles of extracellular signal-regulated kinase (ERK) (lin-45 (ku51), mek-2 (n1989), and mpk-1 (ku1)), c-Jun N-terminal kinase (JNK) (jkk-1 (km2), mek-1 (ks54), jnk-1 (gk7), mkk-4 (ju91)), and p38 ( nsy-1 (ag3), sek-1 (ag1), and pmk-1 (km25)) MAPK cascades. These results suggest that arsenite-induced apoptosis occurs independently of p53/ cep-1 and the DNA damage response (DDR) genes hus-1, clk-2, and egl-1 and that the C. elegans caspase gene ced-3, Apaf-1 homologue ced-4, and the MAPK signaling pathways are essential for germline apoptosis. Moreover, our study demonstrates that C. elegans could be a mammalian in vivo substitute model to study the mechanisms of apoptosis.",
Arsenic,2278441,"Effect of metal composition in lanthanum-doped ferric-based layered double hydroxides and their calcined products on adsorption of arsenate Abstract: A series of lanthanum-doped ferric-based layered double hydroxides with the carbonate intercalation (Mg–Fe–La–LDHs) of different M2+/M3+ molar ratio and their corresponding calcined products were successfully synthesized and characterized. In order to understand the effect of metal compositions in these materials on their adsorption performances for arsenate, various factors such as solution pH, contact time and initial arsenate concentrations were investigated. The results showed that the maximum adsorption capacity for Mg–Fe–La–LDHs decreased with the increment of the M2+/M3+ molar ratio, but the reversed trend occurred for the calcined products of Mg–Fe–La–CLDHs. This difference is closely related to the different adsorption mechanisms for layered double hydroxides (LDHs) and calcined layered double hydroxide (CLDHs). It was found that the adsorption isotherms can be well described by the Langmuir equation, and the adsorption kinetics followed the pseudo-second-order kinetic model. The results suggested that the obtained Mg–Fe–La–LDHs with lower molar ratio of M2+/M3+ in the materials were more suitable for removal of arsenate, while their calcined products Mg–Fe–La–CLDHs with higher molar ratio of M2+/M3+ were efficient adsorbents for arsenate. When the M2+/M3+ molar ratio in the material was 4.38, the maximum adsorption capacity of CLDH-3 was as high as 47.4 mg g?1.",
Arsenic,1337689,"Associations between arsenic exposure and global posttranslational histone modifications among adults in Bangladesh Abstract: BACKGROUND: Exposure to arsenic (As) is associated with an increased risk of several cancers as well as cardiovascular disease, and childhood neuro-developmental deficits. Arsenic compounds are weakly mutagenic, alter gene expression and posttranslational histone modifications (PTHMs) in vitro. METHODS: Water and urinary As concentrations as well as global levels of histone 3 lysine 9 di-methylation and acetylation (H3K9me2 and H3K9ac), histone 3 lysine 27 tri-methylation and acetylation (H3K27me3 and H3K27ac), histone 3 lysine 18 acetylation (H3K18ac), and histone 3 lysine 4 trimethylation (H3K4me3) were measured in peripheral blood mononuclear cells (PBMC) from a subset of participants (N = 40) of a folate clinical trial in Bangladesh (FACT study). RESULTS: Total urinary As (uAs) was positively correlated with H3K9me2 (r = 0.36, P = 0.02) and inversely with H3K9ac (r = -0.47, P = 0.002). The associations between As and other PTHMs differed in a gender-dependent manner. Water As (wAs) was positively correlated with H3K4me3 (r = 0.45, P = 0.05) and H3K27me3 (r = 0.50, P = 0.03) among females and negatively correlated among males (H3K4me3: r = -0.44, P = 0.05; H3K27me3: r = -0.34, P = 0.14). Conversely, wAs was inversely associated with H3K27ac among females (r = -0.44, P = 0.05) and positively associated among males (r = 0.29, P = 0.21). A similar pattern was observed for H3K18ac (females: r = -0.22, P = 0.36; males: r = 0.27, P = 0.24). CONCLUSION: Exposure to As is associated with alterations of global PTHMs; gender-specific patterns of association were observed between As exposure and several histone marks. IMPACT: These findings contribute to the growing body of evidence linking As exposure to epigenetic dysregulation, which may play a role in the pathogenesis of As toxicity.",
Arsenic,628098,"Does arsenic exposure increase the risk for diabetes mellitus? Abstract: OBJECTIVE: Long-term arsenic exposure has been reported to associated with prevalence, incidence, and mortality of diabetes mellitus (DM). A tap water supply system was implemented in the early 1960s in the blackfoot disease (BFD) endemic areas. The objective of this study is to examine whether DM mortality decreased after the improvement of drinking water supply system through elimination of arsenic exposure from artesian well water. METHODS: Standardized mortality ratios (SMRs) for DM were calculated for the BFD endemic area for the years 1971-2000. RESULTS: The study results show that mortality from DM declined in females (but not in males) gradually after the improvement of drinking water supply system. CONCLUSIONS: Based on the reversibility criterion, the association between arsenic exposure and DM is likely to be casual for females but not in males.",
Arsenic,627040,"Uptake of inorganic and organic derivatives of arsenic associated with induced cytotoxic and genotoxic effects in Chinese hamster ovary (CHO) cells Abstract: Humans are exposed to arsenic and their organic derivatives, which are widely distributed in the environment, via food, water, and to a lesser extent, via air. Following uptake, inorganic arsenic undergoes biotransformation to mono- and dimethylated metabolites. Recent findings suggest that the methylation reactions represent a toxification rather than a detoxification pathway. In the present study, the genotoxic effects and the cellular uptake of inorganic arsenic [arsenate, As(i)(V); arsenite, As(i)(III)] and the methylated arsenic species monomethylarsonic acid [MMA(V)], monomethylarsonous acid [MMA(III)], dimethylarsinic acid [DMA(V)], dimethylarsinous acid [DMA(III)], trimethylarsenic oxide [TMAO(V)] were investigated in Chinese hamster ovary (CHO-9) cells. The chemicals were applied at different concentrations (0.1 microM to 10 mM) for 30 min and 1 h, respectively. Cytotoxic effects were investigated by the trypan blue extrusion test and genotoxic effects by the assessment of micronucleus (MN) induction, chromosome aberrations (CA), and sister chromatid exchanges (SCE). Intracellular arsenic concentrations were determined by ICP-MS techniques. Our results show that MMA(III) and DMA(III) induce cytotoxic and genotoxic effects to a greater extent than MMA(V) or DMA(V). Viability was significantly decreased after incubation (1 h) of the cells with > or = 1 microM As(i)(III), > or = 1 microM As(i)(V), > or = 500 microM MMA(III), > or = 100 microM MMA(V), and 500 microM DMA(V) and > or = 0.1 microM DMA(III). TMAO(V) was not cytotoxic at concentrations up to 10 mM. A significant increase of the number of MN, CA and SCE was found for DMA(III) and MMA(III). As(i)(III + V) induced CA and SCE but no MN. TMAO(V), MMA(V) and DMA(V) were not genotoxic in the concentration range tested (up to 5 mM). The nuclear division index (NDI) was not affected by any of the tested arsenic compounds after a recovery period of 14 to 35 h. When the uptake of the chemicals was measured by ICP-MS analysis, it was found that only 0.03% MMA(V) and DMA(V), and 2% MMA(III), As(i)(III) and (V) were taken up by the cells. In comparison, 10% of the DMA(III) dose was taken up. The total intracellular concentration of all arsenic compounds increased with increasing arsenic concentrations in the culture medium. Taken together, these data demonstrate that arsenic compounds in the trivalent oxidation state exhibit the strongest genotoxic effects. Trivalent organoarsenic compounds are more membrane permeable than the pentavalent species. The potency of the DNA damage decreases in the order DMA(III) > MMA(III) > As(i)(III and V) > MMA(V) > DMA(V) > TMAO(V). We postulate that the induction of genotoxic effects caused by the methylated arsenic species is primarily dependent upon their ability to penetrate cell membranes.",
Arsenic,2048043,"Environmental impacts of aquifer thermal energy storage investigated by field and laboratory experiments Abstract: Aquifer thermal energy storage (ATES) uses groundwater to store energy for heating or cooling purposes in the built environment. This paper presents field and laboratory results aiming to elucidate the effects that ATES operation may have on chemical groundwater quality. Field data from an ATES site in the south of the Netherlands show that ATES results in chemical quality perturbations due to homogenisation of the initially present vertical water quality gradient. We tested this hypothesis by numerical modelling of groundwater flow and coupled SO4 transport during extraction and injection of groundwater by the ATES system. The modelling results confirm that extracting groundwater from an aquifer with a natural quality stratification, mixing this water in the ATES system, and subsequent injection in the second ATES well can adequately describe the observation data. This mixing effect masks any potential temperature effects in typical low temperature ATES systems (<25 °C) which was the reason to complement the field investigations with laboratory experiments focusing on temperature effects. The laboratory experiments indicated that temperature effects until 25 °C are limited; most interestingly was an increase in arsenic concentration. At 60 °C, carbonate precipitation, mobilisation of dissolved oxygen concentration, K and Li, and desorption of trace metals like As can occur.",
Arsenic,1597456,Removal of Arsenic from Potable Water by Adsorptive Media Treatment Techniques Abstract: ,
Arsenic,2149345,Arsenic removal with chemical precipitation in drinking water treatment plants in Italy Abstract: ,
Arsenic,69380,"Arsenic in ground water in six districts of West Bengal, India: The biggest arsenic calamity in the world: Part 2: Arsenic concentration in drinking water, hair, nails, urine, skin-scale and liver tissue (biopsy) of the affected people Abstract: In six districts of West Bengal arsenic has been found in ground water above the maximum permissible limit recommended by the WHO of 0.05 mg l-1. This water is used by the villagers for drinking, cooking and other household purposes. These six districts have an area of 34,000 km2 and hold a population of 30 million. Over the last five years we have surveyed only a few small areas of these six affected districts and our survey revealed that, at present, at least 800,000 people from 312 villages in 37 blocks are drinking contaminated water and more than 175,000 people are showing arsenical skin lesions that are the late stages of manifestation of arsenic toxicity. Most of the three stages of arsenic-related clinical manifestations are observed amongst the affected people. The common symptoms are conjunctivitis, melanosis, depigmentation, keratosis and hyperkeratosis; cases of gangrene and malignant neoplasms are also observed. The source of arsenic is geological. We have analysed thousands of arsenic contaminated water samples. Most of the water samples contain a mixture of arsenite and arsenate and in none of them could we detect methylarsonic or dimethylarsenic acid. We have also analysed a large number of urine, hair and nail samples, several skin-scales and some liver tissues (biopsy samples) of the people drinking the arsenic contaminated water and showing arsenical skin lesions. Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) was used for the analysis of hair, nails, urine and skin-scale after decomposition by various techniques. The liver tissues were analysed by Zeeman corrected-ETAAS using a few milligrams of the biopsy samples.",
Arsenic,1015780,"Arsenic mobilizes Langerhans cell migration and induces Th1 response in epicutaneous protein sensitization via CCL21: A plausible cause of decreased Langerhans cells in arsenic-induced intraepithelial carcinoma Abstract: Arsenic, still a significant environmental threat in several regions in the world, induces various cancers, including lungs, skin, and bladder. Arsenic-induced Bowen's disease (As-BD) is generally an indolent cutaneous intraepithelial carcinoma in susceptible people. Patients with As-BD have been found to have attenuated contact hypersensitivity. Skin samples collected from these patients have reduced numbers of Langerhans cells (LCs), the major epidermal antigen presenting cells expressing Langerins. This study uses an epicutaneous protein sensitization model to investigate the mechanism through which LCs are decreased in As-BD. It further investigates the possibility that arsenic alters LC migration and polarizes Th responses. To do this, we patch-sensitized Balb/c mice or DT-treated Langerin-DTR mice (conditional depletion of Langerin(+) cells) with OVA or PBS, and fed them water containing 300ppb arsenic or regular water for 200?l for five days. Ninety-six hours after OVA sensitization, Langerin(+)EpCAM(+) cells in arsenic-treated WT mice were significantly increased in draining lymph nodes and decreased in epidermis without changes in the dermis. Lymph node cells from arsenic-treated WT mice were found to proliferate more than lymph node cells from control PBS-treated mice after OVA challenge in vitro. They also secreted more IFN-? and IL-12, but not IL-4, IL-13, or IL-17. However, cell proliferation and the induction of IFN-? by arsenic were found to be abolished in DT-treated Langerin-DTR mice. The expressions of CCL21 and CXCL12 were also increased in lymph nodes from arsenic-treated WT mice. The administration of a neutralizing antibody against CCL21, but not CXCL12, abolished the increase of LCs in lymph nodes in vivo. The results of this study, the first to study oral arsenic polarization of Th1 responses in epicutaneous protein sensitization through CCL21-mediated LC migration, suggest the chronicity of As-BD without invasion might result from enhanced Th1 responses and altered LC migrations by arsenic.",
Arsenic,1936169,Total and bioavailable metals in two contrasting mining regions (Sudbury in Canada and Lubumbashi in DR-Congo): relation to genetic variation in plant populations Abstract: ,
Arsenic,1034079,"Epidemiology of gastric cancer in Chile: II - Nitrate exposures and stomach cancer frequency Abstract: Nitrate levels in urine and nitrite levels in saliva were determined in school children 11-13 years of age in 2 areas of high stomach cancer mortality located in central Chile and in 2 areas of low stomach cancer mortality located at the extremes of Chile. Levels of both nitrates and nitrites were concurrently determined in selected vegetables obtained in these 4 study areas. Levels of nitrates were significantly higher in the urine of schoolchildren and in vegetables obtained from the northern low-risk area. Levels of nitrites were similar in saliva specimens from all 4 areas, but levels in vegetables were inconsistent. These results are apparently incompatible with the hypothesis of a high nitrate intake in areas of high stomach cancer incidence compared to areas of low incidence. This paradoxical finding suggests that cofactors may be involved in the pathopoiesis of stomach cancer that promote or inhibit the transformation of dietary nitrates to nitrosamines. The soil in the high-risk areas is primarily of volcanic origin, which is reported to be low in levels of selenium. On the other hand, residents of Antofagasta, the northern low-risk area, are known to be exposed to high levels of arsenic. It is possible that the diet of residents of the high incidence area which may be deficient in selenium may enhance promotion of nitrates to nitrosamines as has been reported in the literature, or conversely, that high levels of arsenic or other factors in the diet of individuals in Antofagasta may play a protective role. Other factors may be responsible for the low rate observed in the southern low-risk area.",
Arsenic,2279315,"Levels of toxic arsenic species in native terrestrial plants from soils polluted by former mining activities Abstract: Ten native terrestrial plants from soils polluted by former mining activities (Mónica mine, NW Madrid, Spain), with high total arsenic concentration levels (up to 3500 ?g g(-1)), have been studied to determine the fraction of arsenic present as toxic forms (inorganic and methylated species), which present a higher mobility and therefore the potential risk associated with their reintegration into the environment is high. Roots and aboveground parts were analyzed separately to assess possible transformations from translocation processes. Extractions were carried out with deionized water by microwave-assisted extraction at a temperature of 90 °C and three extraction steps of 7.5 min each. Total extracted arsenic concentrations were determined by inductively coupled plasma atomic emission spectrometry, showing extraction percentages from 9 to 39% (calculated as the ratio between total extracted arsenic (Asext) and total arsenic (AsT) concentrations in plants). Speciation studies, performed by high performance liquid chromatography-photo-oxidation-hydride generation-atomic fluorescence spectrometry, showed the main presence of arsenate (As(v)) (up to 350 ?g g(-1)), followed by arsenite (As(iii)), in both plant parts. Monomethylarsonic acid (MMA) and trimethylarsine oxide (TMAO) were also found only in some plants. On the other hand, the use of 0.5 mol L(-1) acetic acid as an extractant led to higher extraction percentages (33-87%), but lower column recoveries, probably due to the extraction of arsenic compounds different to the toxic free ions studied, which may come from biotransformation mechanisms carried out by plants to reduce arsenic toxicity. However, As(v) concentrations increased up to 800 ?g g(-1) in acid medium, indicating the probable release of As(v) from organoarsenic compounds and therefore a higher potential risk for the environment.",
Arsenic,2088331,"The case of arsenic contamination in the Sardinian Geopark, Italy, analyzed using symbolic machine learning Abstract: ",
Arsenic,1597350,"Recycling and reuse of waste from electricity distribution networks as reinforcement agents in polymeric composites Abstract: Of the waste generated from electricity distribution networks, wooden posts treated with chromated copper arsenate (CCA) and ceramic insulators make up the majority of the materials for which no effective recycling scheme has been developed. This study aims to recycle and reuse this waste as reinforcement elements in polymer composites and hybrid composites, promoting an ecologically and economically viable alternative for the disposal of this waste. The CCA wooden posts were cut, crushed and recycled via acid leaching using 0.2 and 0.4 N H2SO4 in triplicate at 70°C and then washed and dried. The ceramic insulators were fragmented in a hydraulic press and separated by particle size using a vibrating sieve. The composites were mixed in a twin-screw extruder and injected into the test specimens, which were subjected to physical, mechanical, thermal and morphological characterization. The results indicate that the acid treatment most effective for removing heavy metals in the wood utilizes 0.4 N H2SO4. However, the composites made from wood treated with 0.2 N H2SO4 exhibited the highest mechanical properties of the composites, whereas the use of a ceramic insulator produces composites with better thermal stability and impact strength. This study is part of the research and development project of ANEEL (Agência Nacional de Energia Elétrica) and funded by CPFL (Companhia Paulista de Força e Luz).",
Arsenic,733069,"Detection of thyroid hormone receptor disruptors by a novel stable in vitro reporter gene assay Abstract: A stable luciferase reporter gene assay was developed based on the thyroid hormone responsive rat pituitary tumor GH3 cell line that constitutively expresses both thyroid hormone receptor isoforms. Stable transfection of the pGL4CP-SV40-2xtaDR4 construct into the GH3 cells resulted in a highly sensitive cell line (GH3.TRE-Luc), which was further optimized into an assay that allowed the detection of Triiodothyronine (T(3)) and Thyroxine (T(4)) concentrations in the picomolar range after only 24 h of exposure. The greater than 20-fold induction of T(3) relative to the solvent control is illustrative of the high responsiveness of the system. The assay was validated by the quantification of the agonistic effect of the natural hormones (T(3) and T(4)), the acetic acid derivatives of T(3) (triiodothyroaceticacid, or Triac) and T(4) (tetraiodothyroacetic acid, or Tetrac), hydroxy polybrominated diphenylethers (OH-PBDEs), hydroxy polychlorinated biphenyls (OH-PCBs) and the antagonistic action of sodium arsenite (NaAsO(2)). The putative antagonist Amiodarone, Bisphenol A (BPA) and its halogenated derivatives (TCBPA and TBBPA) for which effects reported in the literature are not consistent, showed comparable dose-response curves with a slight agonistic effect (5% of T(3)-max) followed by a slight antagonistic effect. The magnitude and reproducibility of the responses to various compounds confirms this assay as a promising tool for the identification and quantification of specific thyroid hormone receptor disrupting potency of compounds.",
Arsenic,1349169,Cell-cycle dependence of the cytotoxicity and clastogenicity of sodium arsenite in Chinese-hamster ovary cells Abstract: ,
Arsenic,1025474,"Biomarker discovery for arsenic exposure using functional data. Analysis and feature learning of mass spectrometry proteomic data Abstract: Plasma biomarkers of exposure to environmental contaminants play an important role in early detection of disease. The emerging field of proteomics presents an attractive opportunity for candidate biomarker discovery, as it simultaneously measures and analyzes a large number of proteins. This article presents a case study for measuring arsenic concentrations in a population residing in an As-endemic region of Bangladesh using plasma protein expressions measured by SELDI-TOF mass spectrometry. We analyze the data using a unified statistical method based on functional learning to preprocess mass spectra and extract mass spectrometry (MS) features and to associate the selected MS features with arsenic exposure measurements. The task is challenging due to several factors, the high dimensionality of mass spectrometry data, complicated error structures, and a multiple comparison problem. We use nonparametric functional regression techniques for MS modeling, peak detection based on the significant zero-downcrossing method, and peak alignment using a warping algorithm. Our results show significant associations of arsenic exposure to either under- or overexpressions of 20 proteins.",
Arsenic,459921,"Effects of arsenic and UVB on normal human cultured keratinocytes: Impact on apoptosis and implication on photocarcinogenesis Abstract: Inorganic arsenic is an environmental toxin and a human carcinogen. Being a co-mutagen, arsenic enhances carcinogenesis of ultraviolet irradiation on the mouse skin. Apoptosis, a well-regulated cell death process, is essential for cell development and tissue homeostasis. Dysregulation of apoptosis will lead to various kinds of pathological conditions, such as cancers. The purpose of this study is to investigate the apoptotic effect induced by the interactions of arsenic and UVB on cultured human keratinocytes. Cultured keratinocytes were treated with sodium arsenite (1 microM) and/or UVB 50 mJ/cm2 irradiation in different combinations, including arsenic alone (As group), UVB alone (UVB group), arsenic followed by UVB (As/UVB group), and UVB followed by As (UVB/As group) treatments. Our results revealed that a low concentration of sodium arsenite did not induce keratinocytes apoptosis. The UVB group showed obvious elevation of caspase-8, -9, and -3 activities in addition to strong induction of apoptosis as determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling (TUNEL) assay. Similar pro-apoptotic effects were observed in the UVB/As group. In contrast, only subtle changes of cell morphology and survival rate were noticed in the As/UVB group. In addition, the results of Western blot and activity assay of caspase-8, -9, and -3 revealed that neither the receptor nor the mitochondrial apoptotic signaling pathway was activated in the As/UVB group. Therefore, we conclude that the pretreatment of keratinocytes with sodium arsenite decreased the pro-apoptotic effects induced by UVB. This finding corroborated with the animal model studying the effects of arsenic and UVB on carcinogenesis. The molecular mechanisms by which arsenic decreased UVB-induced apoptosis remain to be elucidated.",
Arsenic,1936030,"Biomonitoring of several toxic metal(loid)s in different biological matrices from environmentally and occupationally exposed populations from Panasqueira mine area, Portugal Abstract: In the Panasqueira mine area of central Portugal, some environmental media show higher metal(loid) concentrations when compared with the local geochemical background and the values proposed in the literature for these environmental media. In order to evaluate the effect of the external contamination on selected indexes of internal dose, As, Cd, Cu, Cr, Fe, Hg, Mg, Mn, Mo, Ni, Pb, S, Se, Si, and Zn were quantified by inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry in blood, urine, hair and nail samples from individuals environmentally (N = 41) and occupationally exposed (N = 41). A matched control group (N = 40) was also studied, and data from the three groups were compared. Results obtained agreed with those reported by environmental studies performed in this area, pointing to populations living nearby and working in the mine being exposed to metal(loid)s originated from mining activities. Arsenic was the element with the highest increase in exposed populations. The concentration of other elements such as Cr, Mg, Mn, Mo, Ni, Pb, S, Se, and Zn was also increased, although at a lesser extent, specifically in the individuals environmentally exposed and in females. These findings confirm the need for competent authorities to act as soon as possible in this area and implement strategies aimed to protect exposed populations and the entire ecosystem.",
Arsenic,1337666,"High homocysteine and low folate concentrations in acute aortic dissection Abstract: BACKGROUND: Biomarkers for monitoring progression and prognosis of thoracic aneurysm are of great interest. Homocysteine (Hcy) induces elastolysis in arterial media and may directly affect fibrillin-1 or collagen whereas lipoprotein (Lp) (a) inhibits elastolysis by reducing activation of matrix metallopeptidase-9. METHODS: We studied 31 consecutive patients with acute aortic dissection (AAD) admitted for emergency surgery (group I, 60±13years old, 25 men), 30 consecutive patients with chronic aneurysms of the ascending aorta (group II, 67±12years old, 24 men) and 20 healthy controls (group III, 58±15years old, 14 men). We evaluated Hcy, folate, B12, Lp(a) and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism at baseline. RESULTS: Hcy, folate and B12 differed significantly among the 3 studied groups (P=0.016, P=0.004 and P=0.001, respectively). The levels of Hcy and B12 were significantly higher in group I compared to both groups II and III (P=0.05 and P=0.002, P&lt;0.001 and P=0.017, respectively) and without significant differences between groups II and III (P=0.083 and P=0.124). Folate was significantly lower in group I compared to both groups II and III (P=0.001 and P=0.006, respectively) and without marked difference between groups II and III (P=0.409). No significant difference was found in serum levels of Lp (a) (P=0.074) or among the frequency of MTHFR C677T genotypes. CONCLUSIONS: Patients with AAD present with higher Hcy and lower folate compared to both chronic aneurysms and controls.",
Arsenic,2279081,"Arsenic exposure and bladder cancer: Quantitative assessment of studies in human populations to detect risks at low doses Abstract: While exposures to high levels of arsenic in drinking water are associated with excess cancer risk (e.g., skin, bladder, and lung), exposures at lower levels (e.g., &lt;100-200µg/L) generally are not. Lack of significant associations may result from methodological issues (e.g., inadequate statistical power, exposure misclassification), or a different dose-response relationship at low exposures, possibly associated with a toxicological mode of action that requires a sufficient dose for increased tumor formation. The extent to which bladder cancer risk for low-level arsenic exposure can be statistically measured by epidemiological studies was examined using an updated meta-analysis of bladder cancer risk with data from two new publications. The summary relative risk estimate (SRRE) for all nine studies was elevated slightly, but not significantly (1.07; 95% confidence interval [CI]: 0.95-1.21, p-Heterogeneity [p-H]=0.543). The SRRE among never smokers was 0.85 (95% CI: 0.66-1.08, p-H=0.915), whereas the SRRE was positive and more heterogeneous among ever smokers (1.18; 95% CI: 0.97-1.44, p-H=0.034). The SRRE was statistically significantly lower than relative risks predicted for never smokers in the United States based on linear extrapolation of risks from higher doses in southwest Taiwan to arsenic water exposures &gt;10µg/L for more than one-third of a lifetime. By contrast, for all study subjects, relative risks predicted for one-half of lifetime exposure to 50µg/L were just above the upper 95% CI on the SRRE. Thus, results from low-exposure studies, particularly for never smokers, were statistically inconsistent with predicted risk based on high-dose extrapolation. Additional studies that better characterize tobacco use and stratify analyses of arsenic and bladder cancer by smoking status are necessary to further examine risks of arsenic exposure for smokers.",
Arsenic,2279347,"Controls on the valence species of arsenic in tobacco smoke: XANES investigation with implications for health and regulation Abstract: Arsenic (As) is one of four metals/metalloids in tobacco being considered for regulation. In vitro toxicological response to As varies substantially, determined primarily by valence and compound speciation, and inorganic arsenite (As(III)) compounds are the most toxic to humans. This study uses X-ray absorption near edge structure (XANES) to determine valence states of As from the tobacco plant to the crucial combustion stage that creates respirable smoke. Samples studied include cultivated plants (some burdened with additional As), reference standards, and commercial products, along with smoke condensate and ash from these samples. The relative contributions of As(III) and As(V) to the XANES spectra are analyzed, and a consistent pattern of redox changes emerges. Tobacco leaf and manufactured products tend to be dominated by As(V) whereas combustion produces respirable smoke invariably in As(III) form and ash invariably as As(V). The valence state of precursor tobacco is not a controlling factor because all the As mobilized in smoke is reduced during combustion. This study concludes that tobacco combustion exposes smokers to potentially the most toxic forms of arsenic, and this exposure is magnified in regions where arsenic is present in tobacco crops at relatively high concentrations.",
Arsenic,628558,"Relations between exposure to arsenic, skin lesions, and glucosuria Abstract: OBJECTIVES: Exposure to arsenic causes keratosis, hyperpigmentation, and hypopigmentation and seemingly also diabetes mellitus, at least in subjects with skin lesions. Here we evaluate the relations of arsenical skin lesions and glucosuria as a proxy for diabetes mellitus. METHODS: Through existing measurements of arsenic in drinking water in Bangladesh, wells with and without arsenic contamination were identified. Based on a questionnaire, 1595 subjects > or = 30 years of age were interviewed; 1481 had a history of drinking water contaminated with arsenic whereas 114 had not. Time weighted mean arsenic concentrations and mg-years/l of exposure to arsenic were estimated based on the history of consumption of well water and current arsenic concentrations. Urine samples from the study subjects were tested by means of a glucometric strip. People with positive tests were considered to be cases of glucosuria. RESULTS: A total of 430 (29%) of the exposed people were found to have skin lesions. Corresponding to drinking water with < 0.5, 0.5-1.0, and > 1.0 mg/l of arsenic, and with the 114 unexposed subjects as the reference, the prevalence ratios for glucosuria, as adjusted for age and sex, were 0.8, 1.4, and 1.4 for those without skin lesions, and 1.1, 2.2, and 2.6 for those with skin lesions. Taking exposure as < 1.0, 1.0-5.0, > 5.0-10.0 and > 10.0 mg-years/l of exposure to arsenic the prevalence ratios, similarly adjusted, were 0.4, 0.9, 1.2, and 1.7 for those without and 0.8, 1.7, 2.1, and 2.9 for those with skin lesions. All series of risk estimates were significant for trend, (p < 0.01). CONCLUSIONS: The results suggest that skin lesions and diabetes mellitus, as here indicated by glucosuria, are largely independent effects of exposure to arsenic although glucosuria had some tendency to be associated with skin lesions. Importantly, however, glucosuria (diabetes mellitus) may occur independently of skin lesions.",
Arsenic,2064263,"Bt rice expressing Cry2Aa does not cause direct detrimental effects on larvae of Chrysoperla sinica Abstract: To assess the potential effects of Cry2Aa-expressing insect-resistant Bt rice on Chrysoperla sinica larvae, we conducted two tritrophic bioassays using a non-target (Laodelphax striatellus) and a target herbivore (Chilo suppressalis) as prey. None of the tested life-table parameters of C. sinica did differ when fed with L. striatellus nymphs reared on either Bt or control rice plants. Similarly, C. sinica larval survival and development were not affected when fed C. suppressalis larvae that were reared on Cry2Aa-contained artificial diet compared to those fed control diet. However, the 7-day larval weight was significantly decreased in the Bt treatment and none of the C. sinica larvae developed to the adult stage. To clarify whether the observed effects were due to the direct toxicity of Cry2Aa or prey-quality mediated, we conducted a dietary exposure assay in which the toxicity of Cry2Aa to C. sinica larvae was tested. Potassium arsenate (PA) was included as a positive control. None of the tested life-table parameters of C. sinica was adversely affected when fed Cry2Aa at 500 ?g/ml sucrose solution. In contrast, C. sinica larvae were adversely affected by feeding on sucrose solution containing PA. In the feeding assays, exposure of C. sinica larvae to Cry2Aa was confirmed by ELISA. Our results demonstrate that C. sinica larvae are not sensitive to Cry2Aa at concentrations exceeding the levels that the larvae may encounter in Bt rice fields. Consequently the detrimental effects observed in the tritrophic studies using Bt rice-fed C. suppressalis as prey can be attributed to the decreased prey quality due to the sensitivity of C. suppressalis larvae to Cry2Aa.",
Arsenic,1508624,"Effect of reactive bed mineralogy on arsenic retention and permeability of synthetic arsenic-containing acid mine drainage Abstract: Successive alkalinity producing systems (SAPSs) are widely used for treating acid mine drainage (AMD) and alleviating clogging commonly occurring in limestone systems due to an amorphous ferric precipitate. In this study, iron dust, bone char, micrite and their admixtures were used to treat arsenic-containing AMD. A particular interest was devoted to arsenic removal performance, mineralogical constraints on arsenic retention ability and permeability variation during column experiment for 140days. The results showed that the sequence of the arsenic removal capacity was as follows: bone char&gt;micrite&gt;iron dust. The combination of 20% v/v iron dust and 80% v/v bone char/micrite columns can achieve better hydraulic conductivity and phosphorus-retention capacity than single micrite and bone char columns. The addition of iron dust created reductive environment and resulted in the transformation of coating material from colloidal phase to secondary mineral phase, such as green rust and phosphoerrite, which obviously ameliorates hydraulic conductivity of systems. The sequential extraction experiments indicated that the stable fractions of arsenic in columns were enhanced with help of iron dust compared to single bone char and micrite columns. A combination of iron dust and micrite/bone char represented a potential SAPS for treating As-containing AMD.",
Arsenic,1508707,"Traffic crashes and alcohol outlets in a Brazilian state capital Abstract: OBJECTIVE: Restricting alcohol outlets is being considered as a measure for preventing alcohol-related crashes. However, in many developing countries, alcohol availability is not regulated and its influence on motor vehicle traffic crashes is unknown. This study explores the association between traffic crashes and alcohol outlets in a Brazilian city. METHOD: Data were geocoded and exploratory analysis was conducted using the kernel density estimator. Two generalized additive models (GAMs) were implemented to predict the factors associated with alcohol-related crashes. RESULTS: For 78 percent of the 3840 traffic crashes where the driver was a victim, there was at least one bar located within a 300-m radius. The median distances between an outlet were 124.4 and 130.7 m for a non-alcohol- and alcohol-related crashes, respectively (P =.13). The GAMs did not make evident any significant association between the outlet locations and alcohol-related crashes: the presence of at least one outlet was associated with alcohol-related crashes with an odds ratio (OR) of 0.94 (95% confidence interval [CI] = 0.75-1.17). Alcohol crashes are more likely to be observed among males (OR = 1.58; 95% CI = 1.21-2.06), young drivers vs. those aged 50 years+ (OR = 3.4; 95% CI = 1.79-6.43), and crashes with fatalities (OR = 1.73; 95% CI = 0.98-3.04). CONCLUSIONS: Density of alcohol outlets was high all over the city and both alcohol- and non-alcohol-related crashes occurred near an outlet. The study helps to better understand the relationship between alcohol availability and traffic crashes in a middle-income country where licensing/zoning is absent and suggests that measures for restricting the physical availability of alcohol are necessary, even though further studies are still needed.",
Arsenic,627205,"Arsenic enhancement of skin neoplasia by chronic stimulation of growth factors Abstract: Although numerous epidemiological studies have shown that inorganic arsenicals cause skin cancers and hyperkeratoses in humans, there are currently no established mechanisms for their action or animal models. Previous studies in our laboratory using primary human keratinocyte cultures demonstrated that micromolar concentrations of inorganic arsenite increased cell proliferation via the production of keratinocyte-derived growth factors. As recent reports demonstrate that overexpression of keratinocyte-derived growth factors, such as transforming growth factor (TGF)-a, promote the formation of skin tumors, we hypothesized that similar events may be responsible for those associated with arsenic skin diseases. Thus, the influence of arsenic in humans with arsenic skin disease and on mouse skin tumor development in transgenic mice was studied. After low-dose application of tetradecanoyl phorbol acetate (TPA), a marked increase in the number of skin papillomas occurred in Tg.AC mice, which carry the v-Ha-ras oncogene, that received arsenic in the drinking water as compared with control drinking water, whereas no papillomas developed in arsenic-treated transgenic mice that did not receive TPA or arsenic/TPA-treated wild-type FVB/N mice. Consistent with earlier in vitro findings, increases in granulocyte/macrophage colony-stimulating factor (GM-CSF) and TGF-a mRNA transcripts were found in the epidermis at clinically normal sites within 10 weeks after arsenic treatment. Immunohistochemical staining localized TGF-a overexpression to the hair follicles. Injection of neutralizing antibodies to GM-CSF after TPA application reduced the number of papillomas in Tg.AC mice. Analysis of gene expression in samples of skin lesions obtained from humans chronically exposed to arsenic via their drinking water also showed similar alterations in growth factor expression. Although confirmation will be required in nontransgenic mice, these results suggest that arsenic enhances development of skin neoplasias via the chronic stimulation of keratinocyte-derived growth factors and may be a rare example of a chemical carcinogen that acts as a co-promoter.",
Arsenic,2088366,Vegetative as bioindicators of heavy metals in a semiarid system Abstract: ,
Arsenic,2278804,"Electrochemical production of hydrogen coupled with the oxidation of arsenite Abstract: The production of hydrogen accompanied by the simultaneous oxidation of arsenite (As(III)) was achieved using an electrochemical system that employed a BiOx-TiO2 semiconductor anode and a stainless steel (SS) cathode in the presence of sodium chloride (NaCl) electrolyte. The production of H2 was enhanced by the addition of As(III) during the course of water electrolysis. The synergistic effect of As(III) on H2 production can be explained in terms of (1) the scavenging of reactive chlorine species (RCS), which inhibit the production of H2 by competing with water molecules (or protons) for the electrons on the cathode, by As(III) and (2) the generation of protons, which are more favorably reduced on the cathode than water molecules, through the oxidation of As(III). The addition of 1.0 mM As(III) to the electrolyte at a constant cell voltage (E cell) of 3.0 V enhanced the production of H2 by 12% even though the cell current (I cell) was reduced by 5%. The net effect results in an increase in the energy efficiency (EE) for H2 production (?EE) by 17.5%. Furthermore, the value ?EE, which depended on As(III) concentration, also depended on the applied E cell. For example, the ?EE increased with increasing As(III) concentration in the micromolar range but decreased as a function of E cell. This is attributed to the fact that the reactions between RCS and As(III) are influenced by both RCS concentration depending on E cell and As(III) concentration in the solution. On the other hand, the ?EE decreased with increasing As(III) concentration in the millimolar range due to the adsorption of As(V) generated from the oxidation of As(III) on the semiconductor anode. In comparison to the electrochemical oxidation of certain organic compounds (e.g., phenol, 4-chlorophenol, 2-chlorophenol, salicylic acid, catechol, maleic acid, oxalate, and urea), the ?EE obtained during As(III) oxidation (17.5%) was higher than that observed during the oxidation of the above organic compounds (?EE = 3.0-15.3%) with the exception of phenol at 22.1%. The synergistic effect of As(III) on H2 production shows that an energetic byproduct can be produced during the remediation of a significant inorganic pollutant.",
Arsenic,1519571,"Induction of apoptosis in the rat bone marrow mesenchymal stem cells following sodium arsenite treatment with the dose lesser than that used for treatment of malignant patient Abstract: Objective(s):Arsenic compounds are potent human carcinogen and produce a variety of stress responses in mammalian cells. Recently sodium arsenite has been recommended to be used as anti malignancy drug by American food and drug administration (FDA). In this study, we aimed to determine the apoptosis inducing effect of sodium arsenite on rat bone marrow mesenchymal stem cells exposed in vitro. Methodology:Cell morphology was studied with the help of Hoechst and propidium iodide as well as with single cell gel electrophoresis(comet assay), TUNEL assay and caspase activity base on immunocytochemistry using commercial kit were considered to study the mechanism of cell death. Results:Our result showed that the sodium arsenite with concentration of 0.1 µM in 36 hr induces caspase dependent apoptosis in rat bone marrow mesenchymal stem cells. This concentration is the lowest level of sodium arsenite to be reported with apoptosis induction ability in stem cells. Conclusion:Since sodium arsenite is used in therapy, more research should be carried out on the effect of this chemical on stem cells, especially MSCs.",
Arsenic,1344954,THE CHROMOPHORE SERVING AS BASIS FOR THE DETERMINATION OF ARSENIC WITH SILVER DIETHYLDITHIOCARBAMATE Abstract: ,
Arsenic,1344666,Determination of arsenic in biological-material by atomic-absorption spectrophotometry Abstract: ,
Arsenic,180240,"The effects of chronic arsenic exposure from drinking water on the neurobehavioral development in adolescence Abstract: This cross-sectional study examined the possible influence on the development of cognitive function among adolescents due to long-term arsenic exposure. Forty-nine junior school students drinking arsenic-containing well water and 60 controls matched with age, sex, education, body height, body weight, body mass index, and socioeconomic status were compared. The former was divided into two groups: high and low exposure, with mean cumulative arsenic levels of 520629.0±605824.2 and 13782.2±12886.0 ppm, respectively. Four neurobehavioral tests including continuous performance test (CPT), symbol digit (SD), pattern memory (PM) and switching attention (SA) were applied. A strong correlation between age and education caused collinearity in the multiple regression model (r=0.84, P<0.0001). Only education and sex, excluding age, were entered into the model as covariates. Pattern memory and switching attention were significantly affected by long-term cumulative exposure to arsenic after adjusting for education and sex. It is suggested that the arsenic levels in the well water may be monitored extensively, but if there is no intervention, then neurobehavioral function will not be protected. Limitations of the current study require replication of this effect in other studies to confirm this conclusion.",
Arsenic,1373169,"Arsenic in drinking water and mortality in the Southern Great Plain, Hungary Abstract: Arsenic distribution has been found in drinking waters. A connection between arsenic and other constitutents of water was determined. Close positive correlation was found between arsenic and humic substances over most of the study area. In two smaller areas, there was no correlation between arsenic and humic substances. In these waters, the arsenic distribution is not controlled by organic matter, but by other factors which need further investigations. Examination of mortality in the populations consuming water containing levels of arsenic above and below that permitted did not show any significant differences in standardised mortality ratio (SMR) from all causes of death for both male and female. The SMR from the main causes of death-diseases of the circulatory system and neoplasms-shows controversial results for males and females.",
Arsenic,710815,"Arsenic exposure from drinking water, and all-cause and chronic-disease mortalities in Bangladesh (HEALS): A prospective cohort study Abstract: Millions of people worldwide are chronically exposed to arsenic through drinking water, including 35-77 million people in Bangladesh. The association between arsenic exposure and mortality rate has not been prospectively investigated by use of individual-level data. We therefore prospectively assessed whether chronic and recent changes in arsenic exposure are associated with all-cause and chronic-disease mortalities in a Bangladeshi population.<br /><br /> In the prospective cohort Health Effects of Arsenic Longitudinal Study (HEALS), trained physicians unaware of arsenic exposure interviewed in person and clinically assessed 11 746 population-based participants (aged 18-75 years) from Araihazar, Bangladesh. Participants were recruited from October, 2000, to May, 2002, and followed-up biennially. Data for mortality rates were available throughout February, 2009. We used Cox proportional hazards model to estimate hazard ratios (HRs) of mortality, with adjustment for potential confounders, at different doses of arsenic exposure.<br /><br /> 407 deaths were ascertained between October, 2000, and February, 2009. Multivariate adjusted HRs for all-cause mortality in a comparison of arsenic at concentrations of 10.1-50.0 microg/L, 50.1-150.0 microg/L, and 150.1-864.0 microg/L with at least 10.0 microg/L in well water were 1.34 (95% CI 0.99-1.82), 1.09 (0.81-1.47), and 1.68 (1.26-2.23), respectively. Results were similar with daily arsenic dose and total arsenic concentration in urine. Recent change in exposure, measurement of total arsenic concentrations in urine repeated biennially, did not have much effect on the mortality rate.<br /><br /> Chronic arsenic exposure through drinking water was associated with an increase in the mortality rate. Follow-up data from this cohort will be used to assess the long-term effects of arsenic exposure and how they might be affected by changes in exposure. However, solutions and resources are urgently needed to mitigate the resulting health effects of arsenic exposure.<br /><br /> US National Institutes of Health.",
Arsenic,1797816,"Dietary exposure and health risk assessment for 11 minerals and trace elements in Yaoundé: The Cameroonian Total Diet Study Abstract: Dietary exposure to 11  elements was assessed by the Total Diet Study (TDS) method. Sixty-four pooled samples representing 96.5% of the diet in Yaoundé, Cameroon, were prepared as consumed before analysis. Consumption data were sourced from a household budget survey. Dietary exposures were compared with nutritional or health-based guidance values (HBGV) and to worldwide TDS results. Elevated prevalence of inadequate intake was estimated for calcium (71.6%), iron (89.7%), magnesium (31.8%), zinc (46.9%) and selenium (87.3%). The percentage of the study population exceeding the tolerable upper intake levels was estimated as &lt;3.2% for calcium, iron, magnesium, zinc and cobalt; 19.1% of the population exceeded the HBGV for sodium. No exceedance of the HBGV for inorganic mercury was predicted in the population. The margin of exposure ranged from 0.91 to 25.0 for inorganic arsenic depending on the reference point. The &quot;Fish&quot; food group was the highest contributor to intake for calcium (65%), cobalt (32%) and selenium (96%). This group was the highest contributor to the exposure to total arsenic (71%) and organic mercury (96%). The &quot;Cereals and cereal products&quot; highly contributed to iron (26%), zinc (26%) and chromium (25%) intakes. The &quot;Tubers and starches&quot; highly contributed to magnesium (39%) and potassium (52%) intakes. This study highlights the dietary deficiency of some essential elements and a low dietary exposure to toxic elements in Yaoundé.",
Arsenic,1337553,"Karyotype and DNA-Methylation Responses in Myelodysplastic Syndromes following Treatment with Traditional Chinese Formula Containing Arsenic Abstract: We have previously shown that arsenic-containing Chinese herbal formula, Qing-Huang powder capsule (containing tetraarsenic tetrasulfide, As(4)S(4)), is effective in the treatment of myelodysplastic syndrome (MDS); yet the underlined mechanisms remain unclear. In this study, using standard cytogenetic analysis (G-banded) and global DNA methylation method (ChIP-on-chip assays), we aimed to determine the effect of arsenic-containing Chinese herbal formula on karyotype status and the genomic methylation level in primarily diagnosed MDS patients. Correlation of aberrant DNA methylation and chromosome aberrations in MDS was also investigated. We found that the number of genes with aberrant DNA methylation was highest in MDS patients with normal karyotype, followed by trisomy 8 karyotype, and relatively low in patients with cytogenetic abnormalities other than trisomy 8. Treatment with arsenic-containing Chinese herbal formula had no effects on karyotype status, but resulted in a significant genome-wide demethylation. Our research uncovered a DNA demethylating activity of arsenic-containing Chinese herbal formula in the treatment of MDS.",
Arsenic,2347619,"Identification of redox-regulated components of arsenate (As(V)) tolerance through thiourea supplementation in rice Abstract: Arsenic (As) is a ubiquitously present environmental carcinogen that enters into the human food chain through rice grains. In our previous research, the application of thiourea (TU; a non-physiological thiol based ROS scavenger) has been demonstrated to enhance salt and UV stress tolerance as well as the crop yield under field conditions. These effects were associated with the ability of TU to maintain plant redox homeostasis. Since As stress also induces redox imbalance, the present research was initiated to evaluate the efficiency of TU in regulating As tolerance/accumulation in rice. The supplementation of TU (75 ?M) to As(V) (25 ?M) improved the root growth and also reduced the As concentration by 56% in the aerial parts, which could be attributed to significant downregulation of the Lsi2 transporter responsible for the translocation of As from root to shoot. The fact that these effects were not due to direct interaction between As and TU was confirmed from complexation studies using HPLC-(ICP-MS)-(ESI-MS). Short-term kinetic studies of GSH levels and the GSH/GSSG ratio confirmed the establishment of differential redox states in As and As + TU treated seedlings. The real-time RT-PCR based comparative expression profiling under As with/without TU treatment identified Sultr1;1 and Sultr1;2 as major redox-regulated sulfate transporters. Their specific induction in shoots coupled with enhanced root-to-shoot sulfate translocation (analyzed using (35)S-sulfate as a radiotracer) was observed under TU supplementation. Furthermore, the level of thiolic metabolites (PC2 in roots and GSH and PC3 in shoots) and activities of sulfur metabolism enzymes (ATP sulfurylase and cysteine synthase in roots and 5'-adenylylsulfate reductase in shoot) were also increased with As + TU as compared to As treatment. Thus, this study utilizes the interaction between As and TU to identify the critical redox regulated components of As tolerance in rice.",
Arsenic,627350,"Arsenicals inhibit thioredoxin reductase in cultured rat hepatocytes Abstract: Thioredoxin reductase (TR), an NADPH-dependent flavoenzyme that catalyzes the reduction of many disulfide-containing substrates, plays an important role in the cellular response to oxidative stress. Trivalent arsenicals, especially methyl As that contains trivalent arsenic (MAs(III)), are potent noncompetitive inhibitors of TR purified from mouse liver. Because MAs(III) is produced in the biomethylation of As, it was postulated that the extent of inhibition of TR in cultured rat hepatocytes would correlate with the intracellular concentration of methyl As. Exposure of cultured hepatocytes to inorganic As(III) (iAs(III)), MAs(III), or aurothioglucose (ATG, a competitive inhibitor of TR activity) for 30 min caused a concentration-dependent reduction in TR activity. The estimated IC(50) was &gt;100 microM for iAs(III), approximately 10 microM for ATG, and approximately 3 microM for MAs(III). In hepatocytes exposed to 1 microM MAs(III) for up to 24 h, the inhibition of TR activity was maximal ( approximately 40%) after exposure for 15 min. After exposure for 3 h [when most MAs(III) has been converted to dimethyl As (DMAs)], TR activity in these cells had returned to control levels. Notably, exposure of the cell to 50 microM DMAs(III) did not affect TR activity. In hepatocytes exposed to 10 microM iAs(III) for up to 24 h, the inhibition of TR activity was progressive; at 24 h, activity was reduced approximately 35%. Following exposure to iAs(III) or MAs(III), the extent of inhibition of TR activity correlated strongly with the intracellular concentration of MAs. Taken together, these results suggest that arsenicals formed in the course of cellular metabolism of As are potent inhibitors of TR activity. In particular, MAs(III), an intermediate in the metabolic pathway, is an especially potent inhibitor of TR. Hence, the capacity of cells to produce or consume the intermediates in the pathway for As methylation may be an important determinant of susceptibility to the toxic effects of As.",
Arsenic,1022099,"Antagonistic role of tea against sodium arsenite-induced oxidative DNA damage and inhibition of DNA repair in Swiss albino mice Abstract: Arsenic (As) contamination in groundwater is of increasing health concern in West Bengal, India. Arsenic has been associated with various human cancers, but the precise mechanism of its co-carcinogenic action is not clearly elucidated. Oxidative stress and defective repair mechanisms may promote accumulation of mutations and may be a stepping stone for carcinogenesis. Prevention of arsenic-induced oxidative stress and repair inhibition may reduce the chances of initiation of cancer. Tea polyphenols are reported to have excellent chemopreventive properties against cancer. This study aimed to elucidate the role of tea against arsenic-induced formation of 8-hydroxy-2'-deoxyguanosine (8OHdG) and arsenic-suppressed DNA repair in Swiss albino mice. Both green and black tea gave fruitful results in the reduction of 8OHdG and 8-oxoguanine DNA glycosylase (OGG1) in Swiss albino mice administered sodium arsenite (As III). DNA repair enzymes--such as PARP1, DNA ?-polymerase, XRCC1, DNA ligase III, DNA protein kinase (catalytic subunit), XRCC 4, DNA ligase IV, and DNA topoisomerase II?--were induced by the phytochemicals at both the protein and genetic levels. Thus, tea polyphenols may prove effective in treating arsenic-induced carcinogenesis.",
Arsenic,1451167,"Arsenic exposure and calpain-10 polymorphisms impair the function of pancreatic beta-cells in humans: a pilot study of risk factors for T2DM Abstract: The incidence of type 2 diabetes mellitus (T2DM) is increasing worldwide and diverse environmental and genetic risk factors are well recognized. Single nucleotide polymorphisms (SNPs) in the calpain-10 gene (CAPN-10), which encodes a protein involved in the secretion and action of insulin, and chronic exposure to inorganic arsenic (iAs) through drinking water have been independently associated with an increase in the risk for T2DM. In the present work we evaluated if CAPN-10 SNPs and iAs exposure jointly contribute to the outcome of T2DM. Insulin secretion (beta-cell function) and insulin sensitivity were evaluated indirectly through validated indexes (HOMA2) in subjects with and without T2DM who have been exposed to a gradient of iAs in their drinking water in northern Mexico. The results were analyzed taking into account the presence of the risk factor SNPs SNP-43 and -44 in CAPN-10. Subjects with T2DM had significantly lower beta-cell function and insulin sensitivity. An inverse association was found between beta-cell function and iAs exposure, the association being more pronounced in subjects with T2DM. Subjects without T2DM who were carriers of the at-risk genotype SNP-43 or -44, also had significantly lower beta-cell function. The association of SNP-43 with beta-cell function was dependent on iAs exposure, age, gender and BMI, whereas the association with SNP-44 was independent of all of these factors. Chronic exposure to iAs seems to be a risk factor for T2DM in humans through the reduction of beta-cell function, with an enhanced effect seen in the presence of the at-risk genotype of SNP-43 in CAPN-10. Carriers of CAPN-10 SNP-44 have also shown reduced beta-cell function.",
Arsenic,735000,"The origins of bladder cancer Abstract: Bladder cancer, arising from the transitional cells of the mucosal urothelium, may present as a noninvasive, papillary tumor protruding from the mucosal surface, or as a solid, nonpapillary tumor that invades the bladder wall and has a high propensity for metastasis. The nonpapillary tumors originate from in situ dysplasia. The most common environmental risk for bladder cancer is active smoking; occupational exposure to arsenic or other carcinogens is also a risk factor. A possible familial component to bladder cancer has been described. Conventional models of carcinogenesis suppose the existence of successive mutation events within a specific cell clone, enabling its eventual escape from regulation of cell division and maintenance of genomic integrity. Important new information has emerged from whole-organ mapping of the mucosal genome in bladders resected for invasive cancer (Majewski et al, Lab Invest; published online 5 May 2008). Mapping of genetic hits across the entire mucosa demonstrates genetic alterations in six chromosomal regions, not only in mucosal regions of evident dysplasia, but also in morphologically normal mucosa. These clonally expanded regions cover vast expanses of the bladder surface, as a ‘first wave’ of pre-neoplasia. Target genes in these regions are termed ‘forerunner genes’ (FR genes), based on the concept that these genes enable the initial clonal expansion of in situ urothelial neoplasia. Extensive further analysis of human populations with urothelial cancer implicates genetic polymorphisms in one of these genes, P2RY5, as being present in a familial cluster of cancers of multiple organs, and as imparting risk for development of bladder cancer in active smokers. P2RY5 is a gene encoded within intron 17 of RB1, a prototypic tumor suppressor gene whose expression is lost at a later stage of bladder carcinogenesis. Alterations of the FR gene status provide a novel opportunity to screen individuals at risk for the earliest stage of bladder pre-neoplasia and represent attractive targets for therapeutic and chemopreventive interventions. These findings support the hypothesis that bladder carcinogenesis is initiated by clonal expansion of genetically altered but histologically normal cells that cover broad expanses of the mucosa. Effort must now be given to identifying the biological function of these novel FR genes.",
Arsenic,627245,"Inorganic arsenite potentiates vasoconstriction through calcium sensitization in vascular smooth muscle Abstract: Chronic exposure to arsenic is well known as the cause of cardiovascular diseases such as hypertension. To investigate the effect of arsenic on blood vessels, we examined whether arsenic affected the contraction of aortic rings in an isolated organ bath system. Treatment with arsenite, a trivalent inorganic species, increased vasoconstriction induced by phenylephrine or serotonin in a concentration-dependent manner. Among the arsenic species tested--arsenite, pentavalent inorganic species (arsenate), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV)--arsenite was the most potent. Similar effects were also observed in aortic rings without endothelium, suggesting that vascular smooth muscle plays a key role in enhancing vasoconstriction induced by arsenite. This hypercontraction by arsenite was well correlated with the extent of myosin light chain (MLC) phosphorylation stimulated by phenylephrine. Direct Ca2+ measurement using fura-2 dye in aortic strips revealed that arsenite enhanced vasoconstriction induced by high K+ without concomitant increase in intracellular Ca2+ elevation, suggesting that, rather than direct Ca2+ elevation, Ca2+ sensitization may be a major contributor to the enhanced vasoconstriction by arsenite. Consistent with these in vitro results, 2-hr pretreatment of 1.0 mg/kg intravenous arsenite augmented phenylephrine-induced blood pressure increase in conscious rats. All these results suggest that arsenite increases agonist-induced vasoconstriction mediated by MLC phosphorylation in smooth muscles and that calcium sensitization is one of the key mechanisms for the hypercontraction induced by arsenite in blood vessels.",
Arsenic,2345703,"Arsenic stress in rice: Redox consequences and regulation by iron Abstract: Arsenic (As) contamination is a serious hazard to human health and agriculture. It has emerged as an important threat for rice cultivation mainly in South Asian countries. In this study, we investigated the effect of iron (Fe) supplementation on arsenic (As(V)) induced oxidative stress responses in rice (Oryza sativa L.). Rice seedlings treated with As(V) for 24 and 48 h in presence or absence of 2.5 mM Fe after which the root and shoot tissues were harvested for analysis. The results indicate significant (p ? 0.05) reduction in root and shoot length/dry biomass. Supplementation of Fe showed improved growth responses under stress as compared to As(V) alone. The scanning electron microscopy (SEM) analysis of roots under As(V) treatment for 48 h showed major alterations in root structure and integrity, although no noticeable changes were observed in Fe - supplemented seedlings. Significantly high (p ? 0.05) accumulation of As(V) was observed in root and shoot after 24 and 48 h of stress. However, under Fe - supplementation As accumulation in root and shoot were considerably low after 24 and 48 h of As(V) treatment. The hydrogen peroxide (H2O2) and malondialdehyde (MDA) content in both root and shoot increased significantly (p ? 0.05) after 24 and 48 h of As(V) treatment. In Fe - supplemented seedlings, the levels of H2O2 and MDA were considerably low as compared to As(V) alone. Ascorbate (AsA) and glutathione (GSH) levels also increased significantly (p ? 0.05) under As(V) stress as compared to control and Fe-supplemented seedlings. Activities of catalase (CAT) and superoxide dismutase (SOD) were significantly (p ? 0.05) high after 24 and 48 h of As(V) treatment as compared to Fe-supplemented seedlings. The gene expression analysis revealed up-regulation of metallothionein (MT1, MT2) and nodulin 26-like intrinsic protein (NIP2;1) genes after 5d of As treatment, while their expressions were repressed under Fe-supplementation. Our results indicate that Fe regulates oxidative stress and promotes growth under As stress.",
Arsenic,1552534,"Differential regulation of GLUT1 activity in human corneal limbal epithelial cells and fibroblasts Abstract: The corneal epithelial tissue is a layer of rapidly growing cells that are highly glycolytic and express GLUT1 as the major glucose transporter. It has been shown that GLUT1 in L929 fibroblast cells and other cell lines can be acutely activated by a variety agents. However, the acute regulation of glucose uptake in corneal cells has not been systematically investigated. Therefore, we examined glucose uptake in an immortalized human corneal-limbal epithelial (HCLE) cell line and compared it to glucose uptake in L929 fibroblast cells, a cell line where glucose uptake has been well characterized. We report that the expression of GLUT1 in HCLE cells is 6.6-fold higher than in L929 fibroblast cells, but the HCLE cells have a 25-fold higher basal rate of glucose uptake. Treatment with agents that interfere with mitochondrial metabolism, such as sodium azide and berberine, activate glucose uptake in L929 cells over 3-fold, but have no effect on glucose uptake HCLE cells. Also, agents known to react with thiols, such cinnamaldehyde, phenylarsine oxide and nitroxyl stimulate glucose uptake in L929 cells 3-4-fold, but actually inhibit glucose uptake in HCLE cells. These data suggest that in the fast growing HCLE cells, GLUT1 is expressed at a higher concentration and is already highly activated at basal conditions. These data support a model for the acute activation of GLUT1 that suggests that the activity of GLUT1 is enhanced by the formation of an internal disulfide bond within GLUT1 itself.",
Arsenic,1358225,"Multielement neutron activation analysis of biological material using chemical group separations and high resolution gamma spectrometry Abstract: It has long been recognized that many elements play vital roles in life processes. In recent years, studies have been conducted to determine which trace elements are essential for plant and animal life. Allaway (1) has stated that the trace elements iron, copper, zine, manganese, borom, sodium, cobalt, molybdenum, and vanadium appear essential for plant life. Those necessary for animal life include: iron, iodine, copper, zinc, manganese, cobalt, molybdenum, and selenium as essential trace elements, and fluorine, boron, barium, and strontium as probably essential. It has also been observed that many elements, especially if present in excess quantitites, produce toxicologic effects upon life processes. Although nearly all elements are found in living matter, the roles of many elements have not yet been well characterized.",
Arsenic,627185,"Mytilus trossulus hsp70 as a biomarker for arsenic exposure in the marine environment: Laboratory and real-world results Abstract: The highly conserved heat shock protein 70 (hsp70) is induced by heat and chemical toxins, particularly heavy metals such as arsenic (As). The use of Mytilus trossulus (bay mussel) hsp70 as a 'screening' biomarker for marine heavy metals contamination was assessed. Some studies have found high hsp70 sensitivity to heavy metals, while others have found the opposite. Few studies have realistically used low heavy metals exposures, and fewer have used real-world contamination exposures. Clean sub-tidal mussels from the Puget Sound, Washington State (WA), USA, were acclimatized for 2 weeks and exposed for 24 h to As-spiked seawater (n=9) or to contaminated seawater from an arsenical pesticide plant in Tacoma, WA (n=10) followed by a Western blot for hsp70. Hsp70 inductions were insignificant at 10 microg l(-1) As(III), but were strong at 100 microg l(-1) (p&lt;0.05) and 1000 microg l(-1) (p&lt;0.01), with the induction threshold estimated at 30-50 microg l(-1) As(III). Hsp70 induction roughly correlated with arsenical toxicity, with As(III) &gt; As(V) &gt; (CH(3))(2)As(V). Altogether, the inter-individual variability of hsp70 levels tends to mask inductions at low As concentrations, making it a crude toxicity biomarker. In addressing this problem, the following options could prove promising: (1) pre- or post-stressing specimens for greater hsp70 sensitivity, (2) use of internal protein controls such as actin, (3) use of hsp70-reporter gene constructs, and (4) detection with hsp60, heme oxygenase-1, metallothionein, CYP450, MXR or GPx.",
Arsenic,84913,"An interagency partnership applied to the study of environmental health in the lower Rio Grande Valley of Texas Abstract: BIOSIS COPYRIGHT: BIOL ABS. An environmental monitoring investigation was initiated in the Lower Rio Grande Valley in response to concerns about the potential link between local residents' health and environmental pollution. Concerns expressed by residents of the community related to industrial emissions, agricultural pesticide use, and inadequate infrastructure. A field investigation was conducted jointly by the U.S. Environmental Protection Agency (EPA), the Centers for Disease Control and Prevention (CDC), and the State of Texas during two sampling periods in 1993. The results provided preliminary data about the levels, sources, and pathways of actual human exposure in the Valley. Samples of indoor and outdoor air, house dust, soil, food, drinking water, urine, blood, and breath were collected and analyzed for several compound classes. This paper presents an overview of the study including the study design, the survey methods, participant selection, and communication of the results. This projec",
Arsenic,1337478,"Occupational exposure to herbs containing aristolochic acids increases the risk of urothelial carcinoma in chinese herbalists Abstract: <strong>PURPOSE: </strong>Aristolochic acid can cause urothelial carcinoma. Herbal remedies containing aristolochic acids were previously categorized as proven group 1 human carcinogens by the WHO cancer agency, the International Agency for Research on Cancer. However, the health effect on workers exposed to aristolochic acid is unclear. Fangchi, a representative herb containing aristolochic acid, is commonly used in the Chinese herbal medicine industry. We determined whether workers exposed to fangchi are at increased risk for urothelial carcinoma.<br /><br /><strong>MATERIALS AND METHODS: </strong>We designed a case-control study based in a national representative cohort of Chinese herbalists. This study analyzed 6,564 Chinese herbalists employed between 1985 and 1998. All incident cases of urothelial carcinoma that occurred between 1988 and 2001 were defined as the case group. Controls were selected from the baseline cohort in a randomized manner. A total of 24 cases and 140 controls were included in analysis. Information about fangchi exposure was obtained in a questionnaire survey administered in 2002.<br /><br /><strong>RESULTS: </strong>Processing, selling or dispensing herbs containing fangchi significantly increased the risk of urothelial carcinoma (HR 2.4, 95% CI 1.1-5.3, p = 0.03). This relationship was independent of cigarette smoking or potential arsenic exposure from drinking water from deep wells.<br /><br /><strong>CONCLUSIONS: </strong>Exposure to the Chinese herbal drug fangchi increases the risk of urothelial carcinoma in herbalists. Appropriate medical monitoring is warranted for workers who have similar exposure.",
Arsenic,1776825,"A Computational Study of Detoxification of Lewisite Warfare Agents by British Anti-lewisite: Catalytic Effects of Water and Ammonia on Reaction Mechanism and Kinetics Abstract: trans-2-Chlorovinyldichloroarsine (lewisite, L agent, Lew-I) acts as a blistering agents. British anti-lewisite (BAL, 2,3-dimercaptopropanol) has long been used as an L-agent antidote. The main reaction channels for the detoxification proceed via breaking of As-Cl bonds and formation of As-S bonds, producing stable, nontoxic ring product [(2-methyl-1,3,2-dithiarsolan-4-yl)methanol]. M06-2X/GENECP calculations have been carried out to establish the enhanced rate of detoxification mechanism in the presence of NH3 and H2O catalysts in both gas and solvent phases, which has been modeled by use of the polarized continuum model (PCM). In addition, natural bond orbital (NBO) and atoms in molecules (AIM) analysis have been performed to characterize the intermolecular hydrogen bonding in the transition states. Transition-state theory (TST) calculation establishes that the rates of NH3-catalyzed (2.88 × 10(-11) s(-1)) and H2O-catalyzed (2.42 × 10(-11) s(-1)) reactions are reasonably faster than the uncatalyzed detoxification (5.44 × 10(-13) s(-1)). The results obtained by these techniques give new insight into the mechanism of the detoxification process, identification and thermodynamic characterization of the relevant stationary species, the proposal of alternative paths on modeled potential energy surfaces for uncatalyzed reaction, and the rationalization of the mechanistic role played by catalysts and solvents.",
Arsenic,2343564,"Glyphosate, hard water and nephrotoxic metals: Are they the culprits behind the epidemic of chronic kidney disease of unknown etiology in Sri Lanka? Abstract: The current chronic kidney disease epidemic, the major health issue in the rice paddy farming areas in Sri Lanka has been the subject of many scientific and political debates over the last decade. Although there is no agreement among scientists about the etiology of the disease, a majority of them has concluded that this is a toxic nephropathy. None of the hypotheses put forward so far could explain coherently the totality of clinical, biochemical, histopathological findings, and the unique geographical distribution of the disease and its appearance in the mid-1990s. A strong association between the consumption of hard water and the occurrence of this special kidney disease has been observed, but the relationship has not been explained consistently. Here, we have hypothesized the association of using glyphosate, the most widely used herbicide in the disease endemic area and its unique metal chelating properties. The possible role played by glyphosate-metal complexes in this epidemic has not been given any serious consideration by investigators for the last two decades. Furthermore, it may explain similar kidney disease epidemics observed in Andra Pradesh (India) and Central America. Although glyphosate alone does not cause an epidemic of chronic kidney disease, it seems to have acquired the ability to destroy the renal tissues of thousands of farmers when it forms complexes with a localized geo environmental factor (hardness) and nephrotoxic metals.",
Arsenic,1346690,"The effects of arsenic on the growth and nutritional status of Anadenanthera peregrina, a Brazilian savanna tree Abstract: Anadenanthera peregrina is a Brazilian savanna tree species that occurs naturally in arsenic (As)-contaminated areas, and its As resistance has been associated with arbuscular mycorrhizal–fungi (AMF) symbiosis. A plant's ability to survive in stressful environments is correlated with its nutrition status, which can be affected by As uptake. The present study evaluated the influence of As on the concentrations and distribution of nutrients in the roots and shoots of A. peregrina grown in the absence of AMF. These plants were grown in substrates spiked with 0, 10, 50, and 100 mg As?kg–1 for 25 d under greenhouse conditions, and the concentrations of essential macro- (P, K, Ca, Mg, N, and S) and micro- (Fe, Mn, Cu, Zn, B, and Mo) nutrients in the roots and shoots were then determined. Enhanced As levels increased the concentrations of P, S, and N and decreased Ca, Mg, and Fe. Although the deleterious effects of As on the plants were striking, the internal As levels were high, which indicated some tissue tolerance of A. peregrina.",
Arsenic,2064126,"Unregulated private wells in the Republic of Ireland: Consumer awareness, source susceptibility and protective actions Abstract: While the safety of public drinking water supplies in the Republic of Ireland is governed and monitored at both local and national levels, there are currently no legislative tools in place relating to private supplies. It is therefore paramount that private well owners (and users) be aware of source specifications and potential contamination risks, to ensure adequate water quality. The objective of this study was to investigate the level of awareness among private well owners in the Republic of Ireland, relating to source characterisation and groundwater contamination issues. This was undertaken through interviews with 245 private well owners. Statistical analysis indicates that respondents' source type significantly influences owner awareness, particularly regarding well construction and design parameters. Water treatment, source maintenance and regular water quality testing are considered the three primary “protective actions” (or “stewardship activities”) to consumption of contaminated groundwater and were reported as being absent in 64%, 72% and 40% of cases, respectively. Results indicate that the level of awareness exhibited by well users did not significantly affect the likelihood of their source being contaminated (source susceptibility); increased awareness on behalf of well users was associated with increased levels of protective action, particularly among borehole owners. Hence, lower levels of awareness may result in increased contraction of waterborne illnesses where contaminants have entered the well. Accordingly, focused educational strategies to increase awareness among private groundwater users are advocated in the short-term; the development and introdiction of formal legislation is recommended in the long-term, including an integrated programme of well inspections and risk assessments.",
Arsenic,1021305,"Mechanisms of cell death induced by cadmium and arsenic Abstract: Cadmium (Cd) and arsenic (As) are known toxic metals in humans. As trioxide (As(2)0(3)) has been recently used as a mitochondria-targeting drug in acute promyelocytic leukemia. In the present study, we examined the intracellular action of these metals using rat kidney tubular cells and cells tolerant to the metals. The cells were cultured with CdCl(2) (1-10 micro M) or As(2)O(3) (1-2.5 micro M). Cells tolerant to Cd and As (Cd-T and As-T, respectively) were defined as cells that survived at toxic concentrations of each metal. Both Cd and As induced cell toxicity in a dose-dependent fashion, which was accompanied by fragmented DNA and decreased mitochondrial membrane potential. Intracellular glutathione (GSH) increased with the increase of Cd and As concentration. In Cd-T and As-T cells, GSH levels were twice those observed in normal cells. When each metal-tolerant culture was exposed to the other different metal, i.e., As or Cd, the protective property was maintained. However, when buthionine sulfoximine (BSO) was added to the metal-tolerant cultures, apoptosis was restored in both Cd-T and As-T. Our results indicate that (1) although GSH is increased in NRK52E by the addition of Cd and As, mitochondria-mediated apoptosis can be still induced, (2) the protective property against metal-induced cytotoxicity is identical in Cd-T and As-T cultures, and (3) although GSH was higher in the metal-tolerant cell lines, depression of GSH by BSO induced apoptosis. We conclude that Cd- and As-induced apoptosis is mediated by an identical mechanism involving intracellular GSH reactive oxidation.",
Arsenic,1677624,"Superparamagnetic magnesium ferrite nanoadsorbent for effective arsenic (III, V) removal and easy magnetic separation Abstract: By doping a proper amount of Mg(2+) (?10%) into ?-Fe2O3 during a solvent thermal process, ultrafine magnesium ferrite (Mg0.27Fe2.50O4) nanocrystallites were successfully synthesized with the assistance of in situ self-formed NaCl &quot;cage&quot; to confine their crystal growth. Their ultrafine size (average size of ?3.7 nm) and relatively low Mg-content conferred on them a superparamagnetic behavior with a high saturation magnetization (32.9 emu/g). The ultrafine Mg0.27Fe2.50O4 nanoadsorbent had a high specific surface area of ?438.2 m(2)/g, and demonstrated a superior arsenic removal performance on both As(III) and As(V) at near neutral pH condition. Its adsorption capacities on As(III) and As(V) were found to be no less than 127.4 mg/g and 83.2 mg/g, respectively. Its arsenic adsorption mechanism was found to follow the inner-sphere complex mechanism, and abundant hydroxyl groups on its surface played the major role in its superior arsenic adsorption performance. It could be easily separated from treated water bodies with magnetic separation, and could be easily regenerated and reused while maintaining a high arsenic removal efficiency. This novel superparamagnetic magnesium ferrite nanoadsorbent may offer a simple single step adsorption treatment option to remove arsenic contamination from water without the pre-/post-treatment requirement for current industrial practice.",
Arsenic,1017958,"Quercetin in vesicular delivery systems: evaluation in combating arsenic-induced acute liver toxicity associated gene expression in rat model Abstract: Arsenic, the environmental toxicant causes oxidative damage to liver and produces hepatic fibrosis. The theme of our study was to evaluate the therapeutic efficacy of liposomal and nanocapsulated herbal polyphenolic antioxidant quercetin (QC) in combating arsenic induced hepatic oxidative stress, fibrosis associated upregulation of its gene expression and plasma TGF beta (transforming growth factor beta) in rat model. A single dose of arsenic (sodium arsenite-NaAsO(2), 13 mg/kgb.wt) in oral route causes the generation of reactive oxygen species (ROS), arsenic accumulation in liver, hepatotoxicity and decrease in hepatic plasma membrane microviscosity and antioxidant enzyme levels in liver. Arsenic causes fibrosis associated elevation of its gene expression in liver, plasma TGF ss (from normal value 75.2+/-8.67 ng/ml to 196.2+/-12.07 ng/ml) and release of cytochrome c in cytoplasm. Among the two vesicular delivery systems formulated with QC, polylactide nanocapsules showed a promising result compared to liposomal delivery system in controlling arsenic induced alteration of those parameters. A single dose of 0.5 ml of nanocapsulated QC suspension (QC 2.71 mg/kg b.wt) when injected to rats 1h after arsenic administration orally protects liver from arsenic induced deterioration of antioxidant levels as well as oxidative stress associated gene expression of liver. Histopathological examination also confirmed the pathological improvement in liver. Nanocapsulated plant origin flavonoidal compound may be a potent formulation in combating arsenic induced upregulation of gene expression of liver fibrosis through a complete protection against oxidative attack in hepatic cells of rat liver.",
Arsenic,2088551,"Genome Sequence of Halomonas sp. Strain A3H3, Isolated from Arsenic-Rich Marine Sediments Abstract: We report the genome sequence of Halomonas sp. strain A3H3, a bacterium with a high tolerance to arsenite, isolated from multicontaminated sediments of the l'Estaque harbor in Marseille, France. The genome is composed of a 5,489,893-bp chromosome and a 157,085-bp plasmid.",
Arsenic,1070335,"Elevated lactate dehydrogenase activity and increased cardiovascular mortality in the arsenic-endemic areas of southwestern Taiwan Abstract: Arsenic ingestion has been linked to increasing global prevalence of and mortality from cardiovascular disease (CVD); arsenic can be removed from drinking water to reduce related health effects. Lactate dehydrogenase (LDH) is used for the evaluation of acute arsenic toxicity in vivo and in vitro, but it is not validated for the evaluation of long-term, chronic arsenic exposure. The present study examined the long-term effect of chronic arsenic exposure on CVD and serum LDH levels, after consideration of arsenic metabolism capacity. A total of 380 subjects from an arseniasis-endemic area and 303 from a non-endemic area of southwestern Taiwan were recruited in 2002. Various urinary arsenic species were analyzed using high-performance liquid chromatography (HPLC) and hydride generation systems. Fasting serum was used for quantitative determination of the total LDH activity. A significant dose-response relationship was observed between arsenic exposure and LDH elevation, independent of urinary arsenic profiles (P<0.001). Furthermore, abnormal LDH elevation was associated with CVD mortality after adjustment for Framingham risk scores for 10-year CVD and arsenic exposure (hazard ratio, 3.98; 95% confidence interval, 1.07-14.81). LDH was elevated in subjects with arsenic exposure in a dose-dependent manner. LDH is a marker of arsenic toxicity associated with CVD mortality. Results of this study have important implications for use in ascertaining long-term arsenic exposure risk of CVD.",
Arsenic,1070495,"Inorganic arsenic and basal cell carcinoma in areas of Hungary, Romania, and Slovakia: A case-control study Abstract: Background: Inorganic arsenic (iAs) is a potent carcinogen, but there is a lack of information about cancer risk for concentrations < 100 ?g/L in drinking water.Objectives: We aimed to quantify skin cancer relative risks in relation to iAs exposure < 100 ?g/L and the modifying effects of iAs metabolism.Methods: The Arsenic Health Risk Assessment and Molecular Epidemiology (ASHRAM) study, a case-control study, was conducted in areas of Hungary, Romania, and Slovakia with reported presence of iAs in groundwater. Consecutively diagnosed cases of basal cell carcinoma (BCC) of the skin were histologically confirmed; controls were general surgery, orthopedic, and trauma patients who were frequency matched to cases by age, sex, and area of residence. Exposure indices were constructed based on information on iAs intake over the lifetime of participants. iAs metabolism status was classified based on urinary concentrations of methylarsonic acid (MA) and dimethylarsinic acid (DMA). Associations were estimated by multivariable logistic regression.Results: A total of 529 cases with BCC and 540 controls were recruited for the study. BCC was positively associated with three indices of iAs exposure: peak daily iAs dose rate, cumulative iAs dose, and lifetime average water iAs concentration. The adjusted odds ratio per 10-?g/L increase in average lifetime water iAs concentration was 1.18 (95% confidence interval: 1.08, 1.28). The estimated effect of iAs on cancer was stronger in participants with urinary markers indicating incomplete metabolism of iAs: higher percentage of MA in urine or a lower percentage of DMA.Conclusion: We found a positive association between BCC and exposure to iAs through drinking water with concentrations < 100 ?g/L.",
Arsenic,1351353,Biotic and Abiotic Schwertmannites as Scavengers for As(III): Mechanisms and Effects Abstract: ,
Arsenic,1030887,"Cytological changes in the fish liver following chronic, environmental arsenic exposure Abstract: ",
Arsenic,1343407,Determination of radiative lifetimes in neutral arsenic using time-resolved laser spectroscopy in the vuv region Abstract: Inspired by the recent Hubble Space Telescope first observations of arsenic in an astrophysical object we have determined the natural radiative lifetime of the upper states of two of the three resonance lines of As I. Short pulse laser excitation at 193.7 and 197.2 nm was achieved using different non-linear optical mixing schemes. Using time-resolved spectroscopy we obtain tau(4p(2)5s P-4(3/2))=4.3(5) ns and T(4p(2)5s P-4(1/2)=4.5(5)ns yielding the absorption oscillator strengths f(abs)(193.7 nm) =0.123 (17) and f(abs)(1 97.2 nm)=0.059(8).,
Arsenic,710951,"Impact of smoking and chewing tobacco on arsenic-induced skin lesions Abstract: We recently reported that the main reason for the documented higher prevalence of arsenic-related skin lesions among men than among women is the result of less efficient arsenic metabolism.<br /><br /> Because smoking has been associated with less efficient arsenic methylation, we aimed to elucidate interactions between tobacco use and arsenic metabolism for the risk of developing skin lesions.<br /><br /> We used a population-based case-referent study that showed increased risk for skin lesions in relation to chronic arsenic exposure via drinking water in Bangladesh and randomly selected 526 of the referents (random sample of inhabitants > 4 years old; 47% male) and all 504 cases (54% male) with arsenic-related skin lesions to measure arsenic metabolites [methylarsonic acid (MA) and dimethylarsinic acid (DMA)] in urine using high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICPMS).<br /><br /> The odds ratio for skin lesions was almost three times higher in the highest tertile of urinary %MA than in the lowest tertile. Men who smoked cigarettes and bidis (locally produced cigarettes; 33% of referents, 58% of cases) had a significantly higher risk for skin lesions than did nonsmoking men; this association decreased slightly after accounting for arsenic metabolism. Only two women smoked, but women who chewed tobacco (21% of referents, 43% of cases) had a considerably higher risk of skin lesions than did women who did not use tobacco. The odds ratio (OR) for women who chewed tobacco and who had < or = 7.9%MA was 3.8 [95% confidence interval (CI), 1.4-10] compared with women in the same MA tertile who did not use tobacco. In the highest tertile of %MA or %inorganic arsenic (iAs), women who chewed tobacco had ORs of 7.3 and 7.5, respectively, compared with women in the lowest tertiles who did not use tobacco.<br /><br /> The increased risk of arsenic-related skin lesions in male smokers compared with nonsmokers appears to be partly explained by impaired arsenic methylation, while there seemed to be an excess risk due to interaction between chewing tobacco and arsenic metabolism in women.",
Arsenic,2064199,"Age-related effects of major and trace element concentrations in rat liver and their mutual relationships Abstract: The concentrations of 22 major and trace elements in livers from rats aging from 5 to 113 weeks old were determined. The rats investigated were the same rats previously reported with respect to 29 elements in bones (femur) and 26 elements in kidneys. The samples were decomposed with high-purity nitric acid and hydrogen peroxide. Seven elements (Na, Mg, P, K, Ca, Fe and Zn) were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and 15 elements (Mn, Co, Cu, As, Se, Rb, Sr, Mo, Cd, Sn, Sb, Cs, Ba, Pb and Bi) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of variance (ANOVA) for age variations indicated that the concentrations of many elements, such as Mg, P, K, Mn, Fe, Cu, Zn, Sr, Mo and Cd, were almost constant across the ages of the rats with the exception of 5 weeks old (p&gt;0.05). Arsenic, Pb and Bi showed significant increasing trends, while Na and Co showed decreasing trends (p&lt;0.01). Selenium showed a decreasing trend except at the initial stage of 5-9 weeks old. Calcium, Rb, Sn, Sb, Cs and Ba showed significant age-related variations, but their patterns were not monotonic. The liver clearly contrasts with the kidneys, in which many elements showed significant age-related variations with increasing trends. The concentration ranges of Mg, P, K, Mn, Cu, Zn, and Mo were controlled within 15% across all ages of rats. The homeostasis of the aforementioned elements may be well established in the liver. The toxic elements, such as Cd, Pb and Bi, showed a narrow concentration range among age-matched rats.",
Arsenic,2345641,"A task-oriented circuit training in multiple sclerosis: a feasibility study Abstract: <strong>BACKGROUND: </strong>The aim of this study was to evaluate the safety, feasibility and preliminary effects of a high-intensity rehabilitative task-oriented circuit training (TOCT) in a sample of multiple sclerosis (MS) subjects on walking competency, mobility, fatigue and health-related quality of life (HRQoL).<br /><br /><strong>METHODS: </strong>24 MS subjects (EDSS 4.89?±?0.54, 17 female and 7 male, 52.58?±?11.21 years, MS duration 15.21?±?8.68 years) have been enrolled and randomly assigned to 2 treatment groups: (i) experimental group received 10 TOCT sessions over 2 weeks (2 hours/each session) followed by a 3 months home exercise program, whereas control group did not receive any specific rehabilitation intervention. A feasibility patient-reported questionnaire was administered after TOCT. Functional outcome measures were: walking endurance (Six Minute Walk Test), gait speed (10 Meter Walk Test), mobility (Timed Up and Go test) and balance (Dynamic Gait Index). Furthermore, self-reported questionnaire of motor fatigue (Fatigue Severity Scale), walking ability (Multiple Sclerosis Walking Scale - 12) and health-related quality of life (Multiple Sclerosis Impact Scale - 29) were included. Subjects' assessments were delivered at baseline (T0), after TOCT (T1) and 3 months of home-based exercise program (T2).<br /><br /><strong>RESULTS: </strong>After TOCT subjects reported a positive global rating on the received treatment. At 3 months, we found a 58.33% of adherence to the home-exercise program. After TOCT, walking ability and health-related quality of life were improved (p?&lt;?0.05) with minor retention after 3 months. The control group showed no significant changes in any variables.<br /><br /><strong>CONCLUSIONS: </strong>This two weeks high-intensity task-oriented circuit class training followed by a three months home-based exercise program seems feasible and safe in MS people with moderate mobility impairments; moreover it might improve walking abilities.<br /><br /><strong>TRIAL REGISTRATION: </strong>NCT01464749.",
Arsenic,498666,"Dietary exposure to metals by individuals living near a hazardous waste incinerator in Catalonia, Spain: Temporal trend Abstract: The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) were determined in a number of foodstuffs purchased during 2006 in various localities of Tarragona County (Catalonia, Spain), near a hazardous waste incinerator, which has been operating since 1999. The dietary intake of the above elements by the population of the area was subsequently estimated. The results were compared with those obtained in previous surveys (baseline 1997 and 2002) performed in the same area. The levels of Be, Tl, and V were under their respective limits of detection in all samples. The estimated dietary intakes of the elements analyzed in the current survey by an adult man of 70 kg were the following: 351 mu g/day for As, 4.6 mu g/day for Cd, 57.5 mu g/day for Cr, 7.1 mu g/day for Hg, 2,229 mu g/day for Mn, 78.0 mu g/day for Ni, 39.9 mu g/day for Pb, and 37.9 mu g/day for Sn. On average, fish and seafood were the main contributor to the total dietary intake of As, Cd, and Hg and one of the most important for Pb. In general terms, the differences on metal exposure through dietary intake between the present and our two previous surveys were not particularly relevant. The current intake of the most toxic elements (As, Cd, Hg, and Pb) remains under the respective Provisional Tolerable Weekly Intakes established by the Food and Agriculture Organization/World Health Organization.",
Arsenic,2347751,"Hydrogeological processes controlling the release of arsenic in parts of 24 Parganas district, West Bengal Abstract: A study was conducted to understand the hydrogeological processes dominating in the North 24 Parganas and South 24 Parganas based on representative 39 groundwater samples collected from selected area. The abundance of major ions was in the order of Ca2+ &gt; Na+ &gt; Mg2+ &gt; K+ &gt; Fe2+ for cations and HCO3 (-) &gt; PO4 (3-) &gt; Cl- &gt; SO4 (2-) &gt; NO3 (-) for anions. Piper trilinear diagram was plotted to understand the hydrochemical facies. Most of the samples are of Ca-HCO3 type. Based on conventional graphical plots for (Ca + Mg) vs. (SO4 + HCO3) and (Na + K) vs. Cl, it is interpreted that silicate weathering and ion exchange are the dominant processes within the study area. Previous studies have reported quartz, feldspar, illite, and chlorite clay minerals as the major mineral components obtained by the XRD analysis of sediments. Mineralogical investigations by SEM and EDX of aquifer materials have shown the occurrence of arsenic as coating on mineral grains in the silty clay as well as in the sandy layers. Excessive withdrawal of groundwater for irrigation and drinking purposes is responsible for fluctuation of the water table in the West Bengal. Aeration beneath the ground surface caused by fluctuation of the water table may lead to the formation of carbonic acid. Carbonic acid is responsible for the weathering of silicate minerals, and due to the formation of clay as a product of weathering, ion exchange also dominates in the area. These hydrogeological processes may be responsible for the release of arsenic into the groundwater of the study area, which is a part of North 24 Parganas and South 24 Parganas.",
Arsenic,1788850,"Blood arsenic and cadmium concentrations in end-stage renal disease patients who were on maintenance haemodialysis Abstract: Background: In India, there is a rising burden of chronic diseases like hypertension and diabetes. It has been estimated that 25-40% of these patients are likely to develop chronic kidney disease (CKD), with a significant percentage requiring renal replacement therapy. Haemodialysis is the most common method which is used to treat advanced and permanent kidney failure. Derangements in the metabolism of several toxic and trace elements such as antimony, arsenic cadmium, molybdenum, nickel, and selenium have been reported for several decades in patients with chronically reduced renal functions. Overall, the available literature suggests that the blood levels of some elements such as cadmium, chromium, fluorine, iodine, lead, or vanadium are high in end-stage renal disease (ESRD). Aim and Objectives: Our aim was to study the levels of blood arsenic and cadmium in ESRD patients who were on maintenance haemodialysis (MHD), and to study whether there was any relationship between their concentrations and the duration of the MHD. Methods: The blood lead levels were determined in 50 healthy subjects with normal renal functions and in 50 patients with ESRD, who were on MHD. None of them had any history of smoking or any industrial exposure. Results: The results of the study revealed that the blood arsenic and cadmium concentrations were higher in the ESRD patients who were on MHD than in the healthy adults. The blood arsenic and cadmium concentrations were found to increase with the duration of the MHD. Conclusion: The mild increase in the blood arsenic and cadmium concentrations, with an increase in the duration of the MHD in the study population, may be viewed in the wider context, that a prolonged exposure to arsenic and cadmium, even at low levels, may result in renal damage and/or progression of an already existing CKD.",
Arsenic,2111509,"Diphenylarsinic acid, a chemical warfare-related neurotoxicant, promotes liver carcinogenesis via activation of aryl hydrocarbon receptor signaling and consequent induction of oxidative DAN damage in rats Abstract: Diphenylarsinic acid (DPAA), a chemical warfare-related neurotoxic organic arsenical, is present in the groundwater and soil in some regions of Japan due to illegal dumping after World War II. Inorganic arsenic is carcinogenic in humans and its organic arsenic metabolites are carcinogenic in animal studies, raising serious concerns about the carcinogenicity of DPAA. However, the carcinogenic potential of DPAA has not yet been evaluated. In the present study we found that DPAA significantly enhanced the development of diethylnitrosamine-induced preneoplastic lesions in the liver in a medium-term rat liver carcinogenesis assay. Evaluation of the expression of cytochrome P450 (CYP) enzymes in the liver revealed that DPAA induced the expression of CYP1B1, but not any other CYP1, CYP2, or CYP3 enzymes, suggesting that CYP1B1 might be the enzyme responsible for the metabolic activation of DPAA. We also found increased oxidative DNA damage, possibly due to elevated CYP1B1 expression. Induction of CYP1B1 has generally been linked with the activation of AhR, and we found that DPAA activates the aryl hydrocarbon receptor (AhR). Importantly, the promotion effect of DPAA was observed only at a dose that activated the AhR, suggesting that activation of AhR and consequent induction of AhR target genes and oxidative DNA damage plays a vital role in the promotion effects of DPAA. The present study provides, for the first time, evidence regarding the carcinogenicity of DPAA and indicates the necessity of comprehensive evaluation of its carcinogenic potential using long-term carcinogenicity studies.",
Arsenic,2279522,"The occurrence and dominant controls on arsenic in the Newark and Gettysburg Basins Abstract: Elevated arsenic (As) concentrations in groundwater and rocks have been found in crystalline and sedimentary aquifers from New England to Pennsylvania, USA. The arsenic geochemistry and water-rock interactions of the Northern Appalachian Mountains and the Newark Basin have been researched at length, however, little is known about arsenic in the Gettysburg Basin. Both the Newark and Gettysburg Basins were formed during the breakup of Pangea, sediment deposition occurred during the Triassic and lithologies are of similar depositional environment. We compile and review the work done in the Newark Basin and collect new samples in the Gettysburg Basin for comparison. The Gettysburg Basin has 18%-39% of rock samples with arsenic concentrations greater than the crustal average of 2mg/kg, while the Newark Basin has 73% to 95% of rock samples above the crustal average. The strongest controls on arsenic in rocks of the Gettysburg Basin are the relationship between arsenic and iron and silicon concentrations while the strongest controls in the Newark Basin are the relationship between arsenic and iron and organic carbon concentrations. The groundwater arsenic concentrations follow similarly with 8-39% of water samples from the Gettysburg Basin above 10?g/L and 24-54% of water samples from the Newark Basin above 10?g/L. The strongest controls on arsenic in water of the Gettysburg Basin are pH, alkalinity and silicon, while the strongest controls in the Newark Basin are pH and alkalinity.",
Arsenic,759539,"Using watershed characteristics, sediment, and tissue of resident mollusks to identify potential sources of trace elements to streams in a complex agricultural landscape Abstract: Trace elements used in animal feed additives can be introduced to aquatic environments through application of manures from animal feeding operations to agricultural land as fertilizer. The use of poultry feed additives containing arsenic (As) is of particular concern in the Shenandoah River watershed (Virginia, USA), an agricultural landscape with a high density of poultry operations. This study investigated the relationship between watershed characteristics of Shenandoah River tributaries and trace element concentrations in streambed sediment and tissue of resident mollusks, including: Asian clams (Corbicula fluminea), which are commonly used biomonitors, and pleurocerid snails (Leptoxis carinata), which are generally understudied. Results failed to support the primary hypothesis of a predictive relationship between watershed densities of poultry operations and As concentrations in sediment and mollusk tissue. However, there were statistical relationships between land use in tributary watersheds and other trace elements in sediment (Cu, Mn, Pb, Zn) and tissue (Cd, Hg, Pb). Principal components analysis of the sediment data suggested a possible geologic source of As at some sites. Tissue concentrations of As were significantly higher in snails than in clams, but clams accumulated higher concentrations of other trace elements (Cd, Cr, Hg, Pb, Se). Snails may be useful biomonitors of environmental As, but appear to be less suitable than clams for studies of landscape sources of other trace elements.",
Arsenic,1131473,"Systemic distribution and speciation of diphenylarsinic acid fed to rats Abstract: Diphenylarsinic acid (DPAA) is an environmental degradation product of diphenylarsine chloride or diphenylarsine cyanide, which were chemical warfare agents produced by Japan during the World War II. DPAA is now considered a dangerous environmental pollutant in Kamisu, Japan, where it is suspected of inducing health effects that include articulation disorders (cerebellar ataxia of the extremities and trunk), involuntary movements (myoclonus and tremor), and sleep disorders. In order to elucidate the toxic mechanism of DPAA, we focused on the distribution and metabolism of DPAA in rats. Systemic distribution of DPAA was determined by administering DPAA orally to rats at a single dose of 5.0 mg As/kg body weight, followed by speciation analysis of selected organs and body fluids. Most of the total arsenic burden was recovered in the urine (23% of the dose) and feces (27%), with the distribution in most other organs/tissues being less than 1%. However, compared with the typical distribution of inorganic dietary arsenic, DPAA administration resulted in elevated levels in the brain, testes and pancreas. In contrast to urine, in which DPAA was found mostly in its unmodified form, the tissues and organs contained arsenic that was mostly bound to non-soluble and soluble high molecular weight proteins. These bound arsenic species could be converted back to DPAA after oxidation with H(2)O(2), suggesting that the DPAA bound to proteins had been reduced within the body and was in a trivalent oxidation state. Furthermore, we also detected two unknown arsenic metabolites in rat urine, which were assumed to be hydroxylated arsenic metabolites.",
Arsenic,1597307,"Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project Abstract: A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5 million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river.",
Arsenic,1028664,"Effect of arsenic in endochondral ossification of experimental animals Abstract: Arsenic (As) toxicity is a global health problem affecting millions of people, the most toxic forms being Arsenites [As(III)] and Arsenates [As(V)]. Arsenic intoxication can occur through different exposure routes. The aim of the present work was to determine the effect of As on endochondral ossification and bone remodeling in experimental animals, by means of biochemical, histologic, and histomorphometric determinations. Sixteen male Wistar rats, 100g body weight (b.w.), were divided into two groups: experimental group (n=8), treated with 10mg/l of NaAsO(2) in their drinking water, receiving 0.21mg/kgb.w./day during 45 days; and control group (n=8) remained untreated. On day 45, blood samples were obtained by cardiac puncture to perform hematologic blood counts and biochemical determination. The animals were killed, the tibiae, femurs, kidneys and livers were resected, fixed in formalin and processed histologically. Tibia and femur sections were obtained and stained with H&E. The following histomorphometric parameters were determined on tibia and femur sections: bone volume (BV/TV), thickness of growth plate cartilage (GPC.Th) and thickness of hypertrophic zone (HpZ.Th). Biochemical determinations showed that experimental animals exhibited neutrophilia and a decrease in lymphocytes and monocytes. As levels were below 1 microg/dl in both groups. The femur sections of the experimental group showed (1) a statistically significant increase in total growth cartilage plate thickness (p<0.05) at the expense of the hypertrophic zone (p<0.05); (2) subchondral trabecular bone sealed to the growth plate with a non-significant increase in primary spongiosa bone volume. These results suggest that As alters endochondral ossification.",
Arsenic,1018357,"Airborne arsenic and urinary excretion of arsenic metabolites during boiler cleaning operations in a Slovak coal-fired power plant Abstract: Little information is available on the relationship between occupational exposure to inorganic arsenic in coal fly ash and urinary excretion of arsenic metabolites. This study ws undertaken in a coal-fired power plant in Slovakia during a routine maintenance outage. Arsenic was measured in the breathing zone of workers during 5 consecutive workdays, and urine samples were obtained for analysis of arsenic metabolites--inorganic arsenic (Asi), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)--prior to the start of each shift. Results from a small number of cascade impactor air samples indicated that approximately 90% of total particle mass and arsenic was present in particle size fractions &gt;/= 3.5 micron. The 8-hr time-weighted average (TWA) mean arsenic air concentration was 48.3 microg/m3 (range 0.17-375.2) and the mean sum of urinary arsenic (SigmaAs) metabolites was 16.9 microg As/g creatinine (range 2.6-50.8). For an 8-hr TWA of 10 microg/m3 arsenic from coal fly ash, the predicted mean concentration of the SigmaAs urinary metabolites was 13.2 microg As/G creatinine [95% confidence interval (CI), 10.1-16.3). Comparisons with previously published studies of exposure to arsenic trioxide vapors and dusts in copper smelters suggest that bioavailability of arsenic from airborne coal fly ash (as indicated by urinary excretion) is about one-third that seen in smelters and similar settings. Arsenic compound characteristics, matrix composition, and particle size distribution probably play major roles in determining actual uptake of airborne arsenic.",
Arsenic,1597360,"Selective and sensitive turn-on fluorescent sensing of arsenite based on cysteine fused tetraphenylethene with AIE characteristics in aqueous media Abstract: Herein, a cysteine-functionalized derivative of TPE is presented as the first fluorescent organic dye for selective, label-free, sub-ppb level detection of As(3+) in aqueous media by taking the advantage of the aggregation induced emission feature. Besides, the first discrimination between the most toxic As(3+) and less toxic As(5+) was obtained.",
Arsenic,1351584,Nonliving biomass of marine macrophytes as arsenic(V) biosorbents Abstract: ,
Arsenic,14003,"National Human Exposure Assessment Survey (NHEXAS): Distributions and associations of lead, arsenic, and volatile organic compounds in EPA Region 5 Abstract: The National Human Exposure Assessment Survey (NHEXAS) Phase I field study conducted in EPA Region 5 provides extensive exposure data on approximately 250 study participants selected via probability sampling. Associated environmental media and biomarker (blood, urine) concentration data were also obtained to aid in the understanding of relationships of the exposures to both contaminant sources and doses. Distributional parameters for arsenic (As), lead (Pb), and four volatile organic compounds (VOCs)--benzene, chloroform, tetrachloroethylene, and trichloroethylene--were estimated for each of the relevant media using weighted data analysis techniques. Inter-media associations were investigated through correlation analysis, and longitudinal correlations and models were used to investigate longitudinal patterns. Solid food appeared to be a major contributor to urine As levels, while Pb levels in household (HH) dust, personal air, and beverages all were significantly associated with blood Pb levels. Relatively high (>0.50) longitudinal correlations were observed for tap water Pb and As, as compared to only moderate longitudinal correlations for the personal air VOCs.",
Arsenic,1597339,"Combined use of AFP, CEA, CA125 and CAl9-9 improves the sensitivity for the diagnosis of gastric cancer Abstract: <strong>BACKGROUND: </strong>The detection of serum tumor marker becomes a common method for screening tumors. However, this method has not been widely used for routine gastric cancer screening. In this study we aimed to determine whether the combined use of tumor markers may increase the sensitivity for the diagnosis of gastric cancer.<br /><br /><strong>METHODS: </strong>Serum AFP, CEA, CA125 and CA19-9 levels were measured in 149 patients with gastric cancer, 111 patients with benign gastric diseases and 124 healthy people, who visited the First Affiliated Hospital of Nanchang University from May 2011 to May 2012. Statistical analysis including receiver operating characteristic (ROC) curve, the area under the curve (AUC), and logistic regression analysis was performed to evaluate the diagnostic value of these markers on gastric cancer.<br /><br /><strong>RESULTS: </strong>Serum levels of CEA, CA125, and CA19-9 in gastric cancer group were higher than that in the benign gastric disease group and the healthy control group (P &lt;0.005). The sensitivity of AFP, CEA, CA125 and CA19-9 in the diagnosis of gastric cancer was 4.7-20.8% individually, and increased to 40.3% in combination. By using optimal cut-off value, the sensitivity of CEA, CA125, and CA19-9 for the diagnosis of gastric cancer was improved. Especially, the sensitivity of CEA increased to 58.4% and the sensitivity of combined use of four markers increased to 69.1%. The age and gender had no effects on the diagnostic value of these markers.<br /><br /><strong>CONCLUSIONS: </strong>The determination and application of optimal cut-off values based on ROC curve and logistic regression analysis could improve the diagnosis of gastric cancer based on common tumor markers.",
Arsenic,1358662,"Stress response decreases the interleukin-1beta-induced production of complement component C3 in human intestinal epithelial cells Abstract: Interleukin-1beta (IL-1beta) increases the production of complement component C3 in enterocytes. Heat shock regulates the response to cytokines and other inflammatory mediators in various cell types. We tested the hypothesis that the heat-shock response regulates IL-1beta-induced C3 production in the enterocyte. Cultured Caco-2 cells, a human intestinal epithelial cell line, were treated with sodium arsenite (10-500 microM) for 1 h or subjected to hyperthermia (43 degrees C) for 1-4 h, and allowed to recover for 1 h. The cells were then treated with IL-1beta (0.5 ng/ml) for up to 24 h, whereafter C3 levels were measured by ELISA and C3 mRNA by Northern blot analysis. Heat-shock protein of 72 kDa (hsp72) was determined by Western blot analysis. Treatment of the cells with sodium arsenite or subjecting them to hyperthermia induced the expression of hsp72. The IL-1beta-induced expression of C3 mRNA and C3 production were down-regulated by hyperthermia and sodium arsenite in a dose-dependent fashion. The results suggest that the stress response induced by hyperthermia or sodium arsenite decreases IL-1beta-induced C3 production in human enterocytes.",
Arsenic,787619,"NRF2 Oxidative Stress Induced by Heavy Metals is Cell Type Dependent Abstract: Exposure to metallic environmental toxicants has been demonstrated to induce a variety of oxidative stress responses in mammalian cells. The transcription factor Nrf2 is activated in response to oxidative stress and coordinates the expression of antioxidant gene products. In this study, we describe the development of an Nrf2-specific reporter gene assay that can be used to study the oxidative stress response in multiple cell types. Using five different cell lines, the Nrf2-activating potency of twenty metals was assessed across a range of concentrations. While ten of the metals tested (cadmium, cobalt, copper, gold, iron, lead, mercury, silver, sodium arsenite and zinc) stimulated Nrf2-dependent transcriptional activity in at least three of the engineered cell lines, only three (cadmium, copper and sodium arsenite) were active in all five cell lines. A comparison of metal-induced Nrf2 transcriptional activation revealed significant differences in the absolute magnitude of activation as well as the relative potencies between the cell lines tested. However, there was no direct correlation between activity and potency. Taken together, these results show that the capacity to stimulate Nrf2 activity and relative potencies of these test compounds are highly dependent on the cell type tested. Since oxidative stress is thought to be involved in the mode of action of many toxicological studies, this observation may inform the design of paradigms for toxicity testing for toxicant prioritization and characterization.",
Arsenic,2347629,"Graphene oxide and its application as an adsorbent for wastewater treatment Abstract: Graphene oxide, particularly as magnetic particles, has recently been used as an adsorbent for wastewater treatment in applications such as heavy metals separation (mercury, cadmium, copper, chromium, arsenic) and also organics (antibiotics, dyes, i.e. Reactive black 5, etc.). Selected examples will be given in the present reviewmostly from the literature. The following themes are examined among others: the synthesis route (impregnation, co-precipitation), kinetics of adsorption, thermodynamics, isotherm studies and applications in comparison with other adsorbents. (c) 2013 Society of Chemical Industry",
Arsenic,628125,"Relative genotoxic potency of arsenic and its methylated metabolites Abstract: Arsenic is one of the few identified human carcinogens that has yet to be shown to cause cancer in rodents when the standard bioassay protocols are used. The reasons for this apparent interspecies difference are unclear but may be related to differences between humans and rodents in their detoxification capabilities. Detoxification of arsenic may occur through a methylation pathway. If, in fact, methylation does detoxify arsenic, one would predict that the methylated arsenicals might be less genotoxic than the inorganic arsenicals. To evaluate the hypothesis that the inorganic arsenicals are more mutagenic than the organic arsenicals, we tested sodium arsenite, sodium arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) for their relative mutagenic and clastogenic potentials. We used the L5178Y/TK+/- mouse lymphoma assay which allows the detection of chemicals inducing a broad spectrum of different types of genetic damage. Sodium arsenite and sodium arsenate were active at concentrations of 1-2 micrograms/ml and 10-14 micrograms/ml, respectively. MMA was active between 2500-5000 micrograms/ml; while DMA required almost 10000 micrograms/ml to induce a genotoxic response. The organic arsenicals are thus much less potent as mutagenic agents than the inorganic arsenicals. All four of these arsenicals appear to act by mechanisms that cause chromosomal mutations.",
Arsenic,1337474,"Inorganic arsenic impairs differentiation and functions of human dendritic cells Abstract: Experimental studies have demonstrated that the antileukemic trivalent inorganic arsenic prevents the development of severe pro-inflammatory diseases mediated by excessive Th1 and Th17 cell responses. Differentiation of Th1 and Th17 subsets is mainly regulated by interleukins (ILs) secreted from dendritic cells (DCs) and the ability of inorganic arsenic to impair interferon-? and IL-17 secretion by interfering with the physiology of DCs is unknown. In the present study, we demonstrate that high concentrations of sodium arsenite (As(III), 1-2?M) clinically achievable in plasma of arsenic-treated patients, block differentiation of human peripheral blood monocytes into immature DCs (iDCs) by inducing their necrosis. Differentiation of monocytes in the presence of non-cytotoxic concentrations of As(III) (0.1 to 0.5?M) only slightly impacts endocytotic activity of iDCs or expression of co-stimulatory molecules in cells activated with lipopolysaccharide. However, this differentiation in the presence of As(III) strongly represses secretion of IL-12p70 and IL-23, two major regulators of Th1 and Th17 activities, from iDCs stimulated with different toll-like receptor (TLR) agonists in metalloid-free medium. Such As(III)-exposed DCs also exhibit reduced mRNA levels of IL12A and/or IL12B genes when activated with TLR agonists. Finally, differentiation of monocytes with non-cytotoxic concentrations of As(III) subsequently reduces the ability of activated DCs to stimulate the release of interferon-? and IL-17 from Th cells. In conclusion, our results demonstrate that clinically relevant concentrations of inorganic arsenic markedly impair in vitro differentiation and functions of DCs, which may contribute to the putative beneficial effects of the metalloid towards inflammatory autoimmune diseases.",
Arsenic,2278283,"Sulfate reduction controlled by organic matter availability in deep sediment cores from the saline, alkaline Lake Van (Eastern Anatolia, Turkey) Abstract: As part of the International Continental Drilling Program deep lake drilling project Paleo Van, we investigated sulfate reduction (SR) in deep sediment cores of the saline, alkaline (salinity 21.4%0, alkalinity 155 m mEq-1, pH 9.81) Lake Van, Turkey. The cores were retrieved in the Northern Basin (NB) and at Ahlat Ridge (AR) and reached a maximum depth of 220 m. Additionally, 65-75 cm long gravity cores were taken at both sites. SR rates (SRR) were low (&lt;22 nmol cm-3 day-1) compared to lakes with higher salinity and alkalinity, indicating that salinity and alkalinity are not limiting SR in Lake Van. Both sites differ significantly in rates and depth distribution of SR. In NB, SRR are up to 10 times higher than at AR. SR could be detected down to 19 mblf (meters below lake floor) at NB and down to 13 mblf at AR. Although SRR were lower at AR than at NB, organic matter (OM) concentrations were higher. In contrast, dissolved OM in the pore water at AR contained more macromolecular OM and less low molecular weight OM.VVe thus suggest, that OM content alone cannot be used to infer microbial activity at Lake Van but that quality of OM has an important impact as well. These differences suggest that biogeochemical processes in lacustrine sediments are reacting very sensitively to small variations in geological, physical, or chemical parameters over relatively short distances.",
Arsenic,2347709,"Survey of cosmetics for arsenic, cadmium, chromium, cobalt, lead, mercury, and nickel content Abstract: As part of efforts to assess amounts of inorganic element contamination in cosmetics, the U.S. Food and Drug Administration contracted a private laboratory to determine the total content of seven potentially toxic or allergenic elements in 150 cosmetic products of 12 types (eye shadows, blushes, lipsticks, three types of lotions, mascaras, foundations, body powders, compact powders, shaving creams, and face paints). Samples were analyzed for arsenic, cadmium, chromium, cobalt, lead, and nickel by inductively coupled plasma-mass spectrometry and for mercury by cold vapor atomic fluorescence spectrometry. The methods used to determine the elements were tested for validity by using standard reference materials with matrices similar to the cosmetic types. The cosmetic products were found to contain median values of 0.21 mg/kg arsenic, 3.1 mg/kg chromium, 0.91 mg/kg cobalt, 0.85 mg/kg lead, and 2.7 mg/kg nickel. The median values for cadmium and mercury were below the limits of detection of the methods. The contract requirements, testing procedures, and findings from the survey are described.",
Arsenic,1453811,"Poly(lactic-co-glycolic) acid loaded nano-insulin has greater potentials of combating arsenic induced hyperglycemia in mice: Some novel findings Abstract: Diabetes is a menacing problem, particularly to inhabitants of groundwater arsenic contaminated areas needing new medical approaches. This study examines if PLGA loaded nano-insulin (NIn), administered either intraperitoneally (i.p.) or through oral route, has a greater cost-effective anti-hyperglycemic potential than that of insulin in chronically arsenite-fed hyperglycemic mice. The particle size, morphology and zeta potential of nano-insulin were determined using dynamic light scattering method, scanning electronic and atomic force microscopies. The ability of the nano-insulin (NIn) to cross the blood-brain barrier (BBB) was also checked. Circular dichroic spectroscopic (CD) data of insulin and nano-insulin in presence or absence of arsenic were compared. Several diabetic markers in different groups of experimental and control mice were assessed. The mitochondrial functioning through indices like cytochrome c, pyruvate-kinase, glucokinase, ATP/ADP ratio, mitochondrial membrane potential, cell membrane potential and calcium-ion level was also evaluated. Expressions of the relevant marker proteins and mRNAs like insulin, GLUT2, GLUT4, IRS1, IRS2, UCP2, PI3, PPAR?, CYP1A1, Bcl2, caspase3 and p38 for tracking-down the signaling cascade were also analyzed. Results revealed that i.p.-injected nano-encapsulated-insulin showed better results; NIn, due to its smaller size, faster mobility, site-specific release, could cross BBB and showed positive modulation in mitochondrial signaling cascades and other downstream signaling molecules in reducing arsenic-induced-hyperglycemia. CD data indicated that nano-insulin had less distorted secondary structure as compared with that of insulin in presence of arsenic. Thus, overall analyses revealed that PLGA nano-insulin showed better efficacy in combating arsenite-induced-hyperglycemia than that of insulin and therefore, has greater potentials for use in nano-encapsulated form.",
Arsenic,1015715,"Genome sequence of the facultative anaerobic arsenite-oxidizing and nitrate-reducing bacterium Acidovorax sp. strain NO1 Abstract: Acidovorax sp. strain NO1, isolated from gold mine soil, was shown to be a facultative anaerobic arsenite-oxidizing and nitrate-reducing bacterium. The reported draft genome predicts the presence of genes involved in arsenic metabolism, nitrate reduction, phosphate transport, and multiple metal resistances and indicates putative horizontal gene transfer events.",
Arsenic,1519046,"Evaluation of essential and toxic trace elements in pseudoexfoliation syndrome and pseudoexfoliation glaucoma Abstract: Pseudoexfoliation syndrome (PEX), an age-related disorder of the eye, is associated with significant ophthalmic morbidity and can lead to pseudoexfoliation glaucoma (PEG). The etiology of this disorder has not been clearly understood. Trace elements have been suggested to have roles in the pathogenesis of several disorders. This study aimed to determine whether trace element levels have a role in the development of PEX and/or PEG. Levels of zinc (Zn), copper (Cu), selenium (Se), manganese (Mn), chromium (Cr), cobalt (Co), molybdenum (Mo), nickel (Ni), vanadium (V), arsenic (As), aluminum (Al), mercury (Hg), cadmium (Cd), and strontium (Sr) were determined in serum samples of 32 cases of PEX, 30 cases of PEG, and 32 control subjects using inductively coupled plasma-mass spectrometry. Mn, Mo, and Hg concentrations were found to be significantly increased in patients with PEX. Logistic regression revealed Mn and Hg as the strongest determinants of PEX and Mo as the strongest determinant of PEG in the studied Turkish subjects. Levels of Mn, Cr, Co, Mo, Al, Hg, Sr, Ni, V, and As were determined for the first time in these ophthalmological disorders. Increased levels of serum Mn, Mo, and Hg suggest a possible role of these elements in the pathobiology of PEX.",
Arsenic,2347823,"TOXIC EFFECT OF ARSENATE ON GERMINATION, EARLY GROWTH AND BIOACCUMULATION IN WHEAT (Triticum aestivum L.) Abstract: Damaging influence of arsenate(V) on germination and early growth of wheat (Triticum aestivum L.) was checked through pot bioassays. Four concentrations of As(V) i.e. 0.013, 0.025, 0.038 and 0.05 mg pot(-1) were used to spike sandy loam soil (sand: 76%, silt: 15%, clay: 9%). Different As(V) treatments in the soil resulted in significant reduction in germination rate (G%), germination index (GI) and relative germination rate (RGR), while increased in arsenic response index (ARI). Shoot growth and biomass were significantly declined by 40-90%, and that of roots were decreased by 50-99% in 2-week and 4-weeks old plants. Morphological symptoms like yellowing of leaf margins, stunt roots and stems were observed at higher dose (0.05 mg) of As(V) in 4-week seedling. The tolerance index (T-index) of seedling was decreased and metal accumulation was increased that revealed increase in the seedling sensitivity with increasing concentrations of As(V). Root accumulated more metal than the shoots. It was concluded that As(V) has potential to drastically reduce seed and seedling growth of wheat by accumulating in plant tissues, therefore it is required to assess uptake by plants growing in arsenic contaminated areas to address food security challenging in Pakistan.",
Arsenic,710796,"Anti-endothelial cell IgG from patients with chronic arsenic poisoning induces endothelial proliferation and VEGF-dependent angiogenesis Abstract: An endemic peripheral vascular disorder due to chronic arsenic poisoning, named Blackfoot disease (BFD), occurs in Taiwan. BFD causes destruction of vascular endothelial cells, and an anti-endothelial cell IgG antibody was found in the sera of BFD patients. We studied the role of this IgG antibody (BFD-IgG) in modulating proliferation and angiogenesis of human umbilical vein endothelial cells (HUVECs) and found that a low concentration of BFD-IgG (200 microg/mL) stimulated endothelial cell growth and increased expressions of vascular cell adhesion molecule-1 (VCAM-1), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF). The apoptosis events appeared not altered by addition of BFD-IgG. An in vitro neoangiogenesis assay demonstrated that BFD-IgG promoted the formation of tube-like structures, which was completely abrogated by anti-VEGF neutralizing antibody and partially by NOS inhibitor, L-NAME. We conclude that BFD-IgG at 200 microg/mL results in cell proliferation and enhanced VEGF-dependent angiogenesis in vitro. Those results suggested that a low concentration of BFD-IgG plays a protective role in the pathogenesis or the progression of BFD.",
Arsenic,2149309,"Electrospun amino-functionalized PDMS as a novel SPME sorbent for the speciation of inorganic and organometallic arsenic species Abstract: Sol–gel based amine-functionalized SPME fibers (PDMS-weak anion exchanger) were prepared and used for direct mode extraction of dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and arsenate (As(V)) from aqueous solutions followed by HPLC-ICPMS determination. Two different methods of coating were employed: (i) electrospinning and (ii) dip coating. Electrospinning was used for the first time for preparation of sol–gel based SPME fibers and was found to be superior in terms of extracted amount of arsenicals, coating homogeneity, accessibility of amine groups on the surface, and preparation time for a single fiber. Various parameters such as solution pH, extraction time, agitation speed, extraction temperature, and ionic strength were studied. Optimum extraction conditions were determined as pH of 5.0, extraction time of 30 min, agitation speed of 700 rpm, and extraction temperature of 20 °C. Extraction ability of the novel coating decreased by the addition of NaCl as a consequence of the competition between anionic arsenic species and chloride ions for active sites of the weak anion exchanger. This novel sol–gel coating prepared by electrospinning was found to be promising for SPME applications. Vibrational spectroscopy revealed the alignment of PDMS chains by elongational force under electrospinning process. The chain alignment accordingly orients the pendant amino functional groups perpendicular to the fiber surface, which may develop the free active functional groups available to the medium and lead to the enhancement of the extraction performance. Moreover, the proposed coating strategy through electrospinning might be able to break new ground for various applications in analytical chemistry as well as other disciplines.",
Arsenic,1338865,"Effects of a constructed wetland and pond system upon shallow groundwater quality Abstract: Constructed wetland (CW) and constructed pond (CP) are commonly utilized for removal of excess nutrients and certain pollutants from stormwater. This study characterized shallow groundwater quality for pre- and post-CW and CP system conditions using data from monitoring wells. Results showed that the average concentrations of groundwater phosphorus (P) decreased from pre-CW to post-CW but increased from pre-CP to post-CP. The average concentrations of groundwater total Kjeldahl nitrogen and ammonium ([Formula: see text]) increased from pre-CW (or CP) to post-CW (or CP), whereas the average concentrations of groundwater arsenic (As), chromium, nickel, and zinc (Zn) decreased from pre-CW to post-CW regardless of the well locations. Variations of groundwater cadmium, copper, and Zn concentrations were larger in pre-CP than in post-CP and had a tendency to decrease from pre-CP to post-CP. In general, the average concentrations of groundwater aluminum and manganese decreased and of groundwater calcium, iron, magnesium, and sodium increased from pre-CP to post-CP. The average values of water levels (depth from the ground surface), redox potential, and conductance decreased and of chloride and sulfate ([Formula: see text]) increased after the wetland and pond were constructed regardless of the well locations. Results further revealed that there were significant differences (??=?0.05) between the pre- and post-CW (or CP) for redox potential, water level, and As. This study suggests that the CW-CP system had discernible effects on some of the shallow groundwater quality constituents. This information is very useful for fully estimating overall performance of stormwater treatment with the CW-CP system.",
Arsenic,1017676,"Technical and social evaluation of arsenic mitigation in rural Bangladesh Abstract: Technical and social performances of an arsenic-removal technology--the sono arsenic filter--in rural areas of Bangladesh were investigated. Results of arsenic field-test showed that filtered water met the Bangladesh standard (&lt; 50 microg/L) after two years of continuous use. A questionnaire was administrated among 198 sono arsenic filter-user and 230 non-user families. Seventy-two percent of filters (n = 198) were working at the time of the survey. Another 28% of the filters were abandoned due to breakage. The abandonment percentage (28%) was lower than other mitigation options currently implemented in Bangladesh. Households were reluctant to repair the broken filters on their own. High cost, problems with maintenance of filters, weak sludge-disposal guidance, and slow flow rate were the other demerits of the filter. These results indicate that the implementation approaches of the sono arsenic filter suffered from lack of ownership and long-term sustainability. Continuous use of arsenic-contaminated tubewells by the non-user households demonstrated the lack of alternative water supply in the survey area. Willingness of households to pay (about 30%) and preference of household filter (50%) suggest the need to develop a low-cost household arsenic filter. Development of community-based organization would be also necessary to implement a long-term, sustainable plan for household-based technology.",
Arsenic,1353936,"Metallothionein, glutathione, and cystine transport in pulmonary artery endothelial cells and NIH/3T3 cells Abstract: Both glutathione (gamma-glutamylcysteinylglycine; GSH) and the metalloprotein metallothionein (MT) are composed of approximately one-third cysteine. Both have antioxidant activity and are induced by oxidant stresses and heavy metals. Intracellular cysteine levels may depend on uptake and reduction of extracellular cystine. GSH synthesis can be limited by the activity of the xc- cystine transport system, which is induced by oxidants and other stresses. MT is induced by treatments that also increase GSH levels and may compete with GSH for intracellular cysteine. We investigated the induction of MT and GSH and cystine transport in NIH/3T3 cells and bovine pulmonary artery endothelial cells exposed to cadmium (Cd) or arsenite. Cd and arsenite increased MT and GSH in both cells. Increases in MT and GSH were accompanied by increases in cystine uptake. Inhibition of cystine transport by glutamate decreased GSH levels and blocked Cd-induced GSH increases in both cell types. MT levels were not significantly affected, suggesting that MT synthesis is less sensitive to intracellular cysteine levels than GSH synthesis.",
Arsenic,95507,"Effect of lead and arsenic on murine macrophage response Abstract: #Splenic macrophages are highly efficient in trapping and concentrating foreign substances carried in the blood and also the major sites where antibodies are synthesised and from where they are released into the circulation. Lead and Arsenic as environmental agents are considered to be high priority toxic substances largely due to their carcinogenic potentials in humans. However, these heavy metals as carcinogens remain an enigma because while they are definitely active in humans, carcinogenesis in the rodent model has never been convincingly demonstrated. Although macrophages are predominantly recruited to the site of inflammation during inflammatory distress as well as in immune response, nothing is known about the interaction of lead and arsenic with macrophages and their possible role in immunotoxicologic effect. In the present study it is reported that in vivo lead acetate treatment (10 mg/kg body wt) inhibits the cell adhesion property and alters the cell morphology in the splenic macrophages. Results show that there is a significant decrease in alkaline phosphatase release in lead treated macrophages (6.7 +/- 0.88 IU/100 mL) with respect to control (14.17 +/- 0.18). In vivo exposure of sodium arsenite (0.5 mg/kg body wt) also decreases phagocytic activity for ingestion and digestion of exogenous antigens, such as whole microorganism, as evident from the phagocytic index, 11555.55 +/- 62.86 (in control) to 5555.5 +/- 1571.33 in arsenic treated cells. Arsenic exposed cells release 8.15 +/- 0.05 microM nitric oxide, whereas control cells release 10.95 +/- 0.15 microM of nitric oxide, which is also identical following LPS stimulation. Results show that the functional integrity of the target cell is also decreased after arsenic exposure as obtained from the percentage of DNA fragmentation. A greater percentage of DNA fragmentation upon arsenic treatment (43.1 +/- 0.05%) with respect to control (14.9 +/- 0.34%) indicates that arsenic induces apoptosis. In immune cells which are rapidly proliferating and differentiating, inhibition of these heavy metal induced functions may result in similar degree of toxicity and lead to diseased state.",
Arsenic,1597448,"Phosphorous and arsenic uptake by corn, wheat and soybean from broiler litter ash and egg layer manure ash Abstract: Poultry litter is being incinerated to reduce excess litter, and the ash from incineration is being used as fertilizer. The objective of this study was to compare the availability of phosphorus (P) from broiler litter ash (BLA), egg layer manure ash (ELMA) and calcium phosphate for corn, wheat and soybean. Other elements such as arsenic are also concentrated in the ashed litter. Calcium phosphate, BLA and ELMA were mixed with soil at 40 and 80 mg P kg?1. Crops were grown for about six weeks. Biomass and phosphorus concentrations were highest for plants grown on the calcium phosphate treatments. At the highest phosphorus rate, phosphorus concentrations were 1135, 963 and 939 mg kg?1 in corn shoot for calcium phosphate, ELMA and BLA, respectively. Arsenic concentrations for plants grown on ash treatment were similar to the control. Results from this study indicated that phosphorus in the ash was not readily available for crop uptake.",
Arsenic,1018934,"Melarsoprol refractory T. b. gambiense from Omugo, north-western Uganda Abstract: Culture adapted T. b. gambiense isolated from Northwest Uganda were exposed to 0.001-0.14 microg/ml melarsoprol or 1.56-100 microg/ml DL-alpha-difluoromethylornithine (DFMO). Minimum inhibitory concentrations (MICs) of each drug were scored for each isolate after a period of 10 days drug exposure. The results indicate that T. b. gambiense isolates from Northwest Uganda had elevated MIC values for melarsoprol ranging from 0.009 to 0.072 microg/ml as compared with T. b. gambiense isolates from Cote d'Ivoire with MIC values ranging from 0.001 to 0.018 microg/ml or with T. b. rhodesiense from Southeast Uganda with MIC values from 0.001 to 0.009 microg/ml. All MIC values obtained fell below expected peak melarsoprol concentrations in serum of treated patients. However, it may not be possible to maintain constant drug concentrations in serum of patients as was the case in our in vitro experiments. Importantly, the MIC of 0.072 microg/ml exhibited by one of the isolates from Northwest Uganda was above levels attainable in CSF indicating that this isolate would probably not be eliminated from CSF of treated patients. PCR amplification of the gene encoding the P2-like adenosine transporter followed by restriction digestion with Sfa NI enzyme revealed presence of fragments previously observed in a trypanosome clone with laboratory-induced arsenic resistance. From our findings it appears that reduced drug susceptibility may be one factor for the frequent relapses of sleeping sickness after melarsoprol treatment occurring in Northwest Uganda.",
Arsenic,2278037,"Visualization of periprostatic nerve fibers before and after radical prostatectomy using diffusion tensor magnetic resonance imaging with tractography Abstract: <strong>PURPOSE: </strong>The purpose was to evaluate whether the diffusion tensor imaging (DTI) technique can visualize changes in the numbers of periprostatic nerve fibers before and after nerve-sparing and non-nerve-sparing prostatectomy.<br /><br /><strong>METHOD: </strong>Fifty-two prostate cancer patients underwent 3-T magnetic resonance imaging including DTI before and after prostatectomy.<br /><br /><strong>RESULTS: </strong>After non-nerve-sparing prostatectomy, the numbers of tracts were significantly decreased at base (218.8±198.8 vs. 60.5±88.7), midgland (124.1±134.5 vs. 32.5±45.7), and apex (103.1±127.4 vs. 29.1±57.1). However, after nerve-sparing prostatectomy, the numbers of tracts were not changed significantly at base (170.5±139.7 vs. 127.7±146.0), midgland (134.3±140.8 vs. 83.7±58.3), and apex (64.1±68.4 vs. 62.3±61.9).<br /><br /><strong>CONCLUSION: </strong>DTI technique may be feasible for visualization of periprostatic nerve fibers.",
Arsenic,2064152,"Hair arsenic concentrations of residents living in Nevsehir province, Turkey Abstract: ",
Arsenic,628606,"Prevention of aneuploidy by S-adenosyl-methionine in human cells treated with sodium arsenite Abstract: Alterations in methyl group's metabolism affect availability of S-adenosyl-l-methionine (SAM); these modifications can be originated by enzyme polymorphisms, nutritional deficiencies, and exposure to chemical agents. There are several types of chemicals that interfere with methyl groups, among them is arsenic. It deserves special attention because it modifies a number of cell functions that influence the development of diseases such as cancer. Since part of arsenic's toxicity is influenced by changes on SAM availability, in a previous study we investigated whether exogenous addition of SAM to cells treated with sodium arsenite (NaAsO2) has an effect on its genotoxicity. Results demonstrated that SAM reduces the frequency of cells presenting micronuclei (MN) and tubulin-cytoskeleton defects after treatment with NaAsO2. MN are fragments of the cell nucleus that may contain whole chromosomes or chromosome fragments depending on whether they derive either from the aneugenic or from the clastogenic action of chemicals. Therefore one question generated by these results was whether SAM reduced only the frequency MN resulting from aneugenic damage. To answer this question, in the present work we used an all-centromere DNA probe to distinguish the type of MN reduced by SAM after treatment with NaAsO2 and vinblastine. In addition, the capacity of SAM to reduce clastogenicity was also evaluated. Results show that SAM decreases the frequency of cells with MN containing whole chromosomes in cultures treated either with NaAsO2 or with vinblastine; however, induction of double-strand breaks by NaAsO2 was not prevented by SAM.",
Arsenic,1508509,"Role of heavy metal resistant Ochrobactrum sp. and Bacillus spp. strains in bioremediation of a rice cultivar and their PGPR like activities Abstract: The present study demonstrates the metal toxicity ameliorating and growth promoting abilities of three different bacterial isolates when applied to rice as host plant. The three bacterial strains included a cadmium resistant Ochrobactrum sp., a lead resistant Bacillus sp. and an arsenic resistant Bacillus sp. designated as CdSP9, PbSP6, and AsSP9, respectively. When these isolates were used as inocula applied to metal-treated rice plants of variety Satabdi, the germination percentage, relative root elongation (RRE), amylase and protease activities were increased. The toxic effect of metal was reduced in presence of these bacteria. The overall biomass and root/shoot ratio were also enhanced by bacterial inoculation. Hydroponic studies showed that the superoxide dismutase (SOD) activity and malondialdehyde (MDA) level, which had been increased in the presence of metal stress in rice roots, were lowered by the bacterial inoculation. In addition, all three strains were 1-aminocyclopropane-1-carboxylate (ACC) deaminase and catalase positive, whereas siderophore producing ability was lacking in PbSP6. However, both PbSP6 and AsSP9 were protease positive and could hydrolyse starch. The data indicate that these bacteria have promise for bioremediation as well as for plant growth promotion.",
Arsenic,1019604,"Cancer mortality trends in a Blackfoot disease endemic community of Taiwan following water source replacement Abstract: Blackfoot disease is an endemic peripheral vascular disease found among people in a limited area on the southwest coast of Taiwan, where artesian well water has a high concentration of arsenic and was used since the turn of this century. This is an important public health problem and was noted by the authorities, who began improving the water supply in such communities in 1956. This enabled us to test the relationship between arsenic and malignant tumors using a specific exposed community. Study subjects were divided into four groups according to age (under or over 40 yr) and gender. Two methods were used for the estimation of the age-adjusted mortality rate ratios. First using the first time interval (1971-1973) as the standard, the mortality rate ratio for all malignant tumors was estimated from this interval through to the last interval (1992-1994) using Poisson regression. Cancers that were found to be related to arsenic in previous reports, such as liver, lung, bladder, kidney, and skin cancers, were examined and other malignant tumors except these cancers were also assessed. The same calculations were performed for all of Chiayi and Tainan counties, excluding the study areas, which were used as the local reference, and for the general population of Taiwan, which was used as a national reference group. Second, mortality rate ratios for the study area were compared to the local and national reference for the same time intervals for each disease category. From our results, significantly declining trends for mortality rate ratios of all malignant tumors with 1971-1973 as the standard were found for the study areas, especially in females. A decrease of mortality rate ratios from malignant cancers, compared to the local or national references, was found in those aged over 40 yr for both sexes. The decreases are mainly due to a fall in internal and skin cancer mortality rates. In conclusion, our results suggest that the improvement of drinking water supply to eliminate arsenic exposure from artesian well water decreased the mortality incidence of arsenic-related cancers in blackfoot disease endemic communities.",
Arsenic,1597455,"Heavy metals in Chinese therapeutic foods and herbs Abstract: In the present study 15 samples of Chinese therapeutic foods and herbs that are frequently consumed by people in both the East and West are analyzed, for the content of cadmium, mercury, lead, arsenic, cuprum and zinc, by atomic absorption spectrophotometer. The results showed that the highest mean value for Cd(0.49 mg·kg-1), Hg(0.34 mg·kg-1), Pb(9.01 mg·kg-1), As(3.26 mg·kg-1), Cu(33.56 mg·kg-1) and Zn(38.32 mg·kg-1) were found in Radix Salviae Miltitorrhizae, Radix Puerariae, Radix Salviae Miltitorrhizae , Radix Sophorae Flavescentis , Fructus Crataegi , Herba andrographis , respectively. The Cd levels of two samples and Cu levels of one sample were found to be higher than the recommended values of Food and Drug Administration (FDA) and World Health Organization (WHO), and may constitute a health hazard for consumers. Mercury, lead, and arsenic levels of one sample were higher than the recommended limit of China Pharmacopoeia, but it were below the WHO and FDA. All other heavy metals in other medicinal plants were found below the recommended tolerable limits.",
Arsenic,1240373,"Impact of atmospheric deposition of As, Cd and Pb on their concentration in carrot and celeriac Abstract: Root crops, carrot and celeriac, were exposed to atmospheric deposition in a polluted versus reference area. An effect was observed on the As, Cd and Pb concentrations of the leaves and the storage organs. The concentrations in the whole storage organs correlated well with atmospheric deposition, which shows that they even could be used for biomonitoring. Nevertheless, leaves remain much more appropriate. The results revealed also a significant increase of the As and Cd concentration in the consumable part of the storage organs as a function of their atmospheric deposition. As such the experiments allowed deriving regression equations, useful for modeling the atmospheric impact of trace elements on the edible parts of root crops. For Pb, however, there was hardly any significant impact on the inner parts of the storage organs and as such the transfer of Pb in the food chain through root crops can be considered to be negligible.",
Arsenic,1519072,"Expression of Arsenic Regulatory Protein in Escherichia coli for Selective Accumulation of Methylated Arsenic Species Abstract: ArsR is a metalloregulatory protein with high selectivity and affinity toward arsenic. We hereby report the expression of ArsR in Escherichia coli by cell engineering, which significantly enhances the adsorption/accumulation capacity of methylated arsenic species. The ArsR-expressed E. coli cells (denoted as E. coli-ArsR ) give rise to 5.6-fold and 3.4-fold improvements on the adsorption/accumulation capacity for monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), with respect to native E. coli cells. The uptake of MMA and DMA by the E. coli-ArsR is a fast process fitting Langmuir adsorption model. It is interesting to note that the accumulation of methylated arsenic is virtually not affected by the presence of competing heavy-metal species, at least 10 times of Cd(II) and Pb(II) are tolerated for the adsorption of 1 mg L(-1) methylated arsenic. In addition, an ionic strength of up to 2 g L(-1) Na(+) poses no obvious effect on the sorption of 1 mg L(-1) MMA and DMA. Furthermore, the accumulation of MMA and DMA is less sensitive to the variation of pH value, with respect to the blank control cells. Consequently, 82.4% of MMA and 96.3% of DMA at a concentration of 50 ?g L(-1) could be readily removed from aqueous medium by 12 g L(-1) of E. coli-ArsR . This illustrates a great potential for the E. coli-ArsR for selective remediation of methylated arsenic species in waters, even in the presence of a high concentration of salts.",
Arsenic,1797828,"Dust exposure is associated with increased lung function loss among workers in the Norwegian silicon carbide industry Abstract: <strong>OBJECTIVES: </strong>To investigate the relationship between dust exposure and annual change in lung function among employees in Norwegian silicon carbide (SiC) plants using a quantitative job exposure matrix (JEM) regarding total dust.<br /><br /><strong>METHODS: </strong>All employees, 20-55 years of age by inclusion (n=456), were examined annually for up to 5 years (1499 examinations). Spirometry was performed at each examination, and a questionnaire encompassing questions of respiratory symptoms, smoking status, job and smoking history, and present job held was completed. A JEM was constructed based on 1970 personal total dust exposure measurements collected during the study period. The association between lung function and total dust exposure was investigated using linear mixed models.<br /><br /><strong>RESULTS: </strong>The annual change in forced expiratory volume (FEV) in one second per squared height, FEV1/height(2), per mg/m(3) increase in dust exposure was -2.3 (95% CI -3.8 to -0.79) (mL/m(2))×year(-1). In an employee of average height (1.79 m) and exposure (1.4 mg/m(3)) the estimated contribution to the annual change in FEV1 associated with dust was 10.4 mL/year. The annual change in FEV1/height(2) in current, compared with non-smokers was -1.9 (-7.2 to 3.4) (mL/m(2))×year(-1). The estimated overall annual decline in FEV1 among current and non-smokers in the highest exposed group was -91.2 (-124.3 to -58.1) (mL/m(2))×year(-1) and -49.0 (-80.2 to -17.8) (mL/m(2))×year(-1), respectively.<br /><br /><strong>CONCLUSIONS: </strong>Dust exposure, expressed by a quantitative JEM, was found to be associated with an increased yearly decline in FEV1 in employees of Norwegian SiC plants.",
Arsenic,1508679,"Metal Accumulation and Health Effects in Raccoons (Procyon lotor) Associated with Coal Fly Ash Exposure Abstract: Approximately 5.4 million cubic yards of coal fly ash and water spilled into the Emory River embayment of Watts Bar Reservoir in east Tennessee on Dec 22, 2008. Raccoons were collected in 2009 and 2010 from the spill site (10/y) and unexposed areas (5/y) to determine whether metals and metalloids were accumulating in raccoons and if any negative health effects resulted from exposure to the spilled coal fly ash. Tissues were analyzed from each animal to determine the concentrations of 26 metals/metalloids. Complete blood cell counts (CBC), plasma biochemistry panels, and histopathology of select tissues also were performed. Results were analyzed by year and exposure status. Although significant differences were present in some tissues for some metals/metalloids, only arsenic in hair, iron in muscle, nickel in hair, selenium in hair and muscle, strontium in hair, and vanadium in hair and liver were increased in spill site animals (one or both years) compared with unexposed animals. No clinically important differences were observed between groups regarding CBC or plasma biochemistry analyses. Lesions were observed on histopathology in some tissues, but there was no difference in the prevalence of lesions between spill site and unexposed animals. There does not seem to be any important accumulation of metals/metalloids or negative health effects in raccoons associated with exposure to coal fly ash compared with unexposed animals.",
Arsenic,628760,"Biomarkers of cadmium and arsenic interactions Abstract: Advances in proteomics have led to the identification of sensitive urinary biomarkers of renal dysfunction that are increasingly used in toxicology and epidemiology. Recent animal data show that combined exposure to inorganic arsenic (As) and cadmium (Cd) gives rise to more pronounced renal toxicity than exposure to each of the agents alone. In order to examine if similar interaction occurs in humans, renal dysfunction was studied in population groups (619 persons in total) residing in two metal contaminated areas in China: mainly a Cd contaminated area in Zhejiang province (Z-area) and mainly a As contaminated area in Guizhou province (G-area). Nearby control areas without excessive metal exposure were also included. Measurements of urinary beta(2)-microglobulin (UB2MG), N-acetyl-beta-glucosaminidase (UNAG), retinol binding protein (URBP) and albumin (UALB) were used as markers of renal dysfunction. Urinary Cd (UCd) and total As (UTAs) were analyzed by graphite-furnace atomic absorption spectrometry. Urinary inorganic As and its mono- and di-methylated metabolites (UIAs) were determined by Hydride generation. Results. As expected, the highest UCd values occurred in Z-area (Geometric mean, GM 11.6 microg/g crea) while the highest UTAs values occurred in G-area (GM = 288 microg/g crea). Statistically significant increases compared to the respective control area were present both for UTAs, UCd and for UB2MG, UNAG and UALB in Z-area as well as in G-area. UIAs was determined only in Z area. In G-area, there was a clear dose-response pattern both in relation to UTAs and UCd for each of the biomarkers of renal dysfunction. An interaction effect between As and Cd was demonstrated at higher levels of a combined exposure to As and Cd enhancing the effect on the kidney. In Z-area an increased prevalence of B2MG-uria, NAG-uria and ALB-uria was found in relation to UCd, but no relationship to UTAs was found. A statistically significant relationship between UIAs and UB2MG was found among women in this area and an interaction between As and Cd was indicated for B2MG. Conclusion. The present studies, which employed sensitive biomarkers of renal dysfunction, give support to the idea that human co-exposure to Cd and inorganic arsenic gives rise to more pronounced renal damage than exposure to each of the elements alone, but further studies are needed to establish and clarify this interaction.",
Arsenic,1255658,"Metabolism of arsenic and its toxicological relevance Abstract: Arsenic is a worldwide environmental pollutant and a human carcinogen. It is well recognized that the toxicity of arsenicals largely depends on the oxidoreduction states (trivalent or pentavalent) and methylation levels (monomethyl, dimethyl, and trimethyl) that are present during the process of metabolism in mammals. However, presently, the specifics of the metabolic pathway of inorganic arsenicals have yet to be confirmed. In mammals, there are two possible mechanisms that have been proposed for the metabolic pathway of inorganic arsenicals, oxidative methylation, and glutathione conjugation. Oxidative methylation, which was originally proposed in fungi, is based on findings that arsenite (iAs(III)) is sequentially converted to monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) in both humans and in laboratory animals such as mice and rats. However, recent in vitro observations have demonstrated that arsenic is only methylated in the presence of glutathione (GSH) or other thiol compounds, which strongly suggests that arsenic is methylated in trivalent forms. The glutathione conjugation mechanism is supported by findings that have shown that most intracellular arsenicals are trivalent and excreted from cells as GSH conjugates. Since non-conjugated trivalent arsenicals are highly reactive with thiol compounds and are easily converted to less toxic corresponding pentavalent arsenicals, the arsenic-glutathione conjugate stability may be the most important factor for determining the toxicity of arsenicals. In addition, &quot;being a non-anionic form&quot; also appears to be a determinant of the toxicity of oxo-arsenicals or thioarsenicals. The present review discusses both the metabolism of arsenic and the toxicity of arsenic metabolites.",
Arsenic,1022027,"Arsenic toxicity in a sediment-dwelling polychaete: Detoxification and arsenic metabolism Abstract: The accumulation, subcellular distribution and speciation of arsenic in the polychaete Arenicola marina were investigated under different laboratory exposure conditions representing a range of metal bioavailabilities, to gain an insight into the physiological mechanisms of how A. marina handles bioaccumulated arsenic and to improve our understanding of the potential ecotoxicological significance of bioaccumulated arsenic in this deposit-feeder. The exposure conditions included exposure to sublethal concentrations of dissolved arsenate, exposure to sublethal concentrations of sediment-bound metal mining mixtures, and exposure to lethal concentrations of sediment-bound metal mining mixtures and arsenic- and multiple metal-spiked sediments. The sub-lethal exposures indicate that arsenic bioaccumulated by the deposit-feeding polychaete A. marina is stored in the cytosol as heat stable proteins (~50%) including metallothioneins, possibly as As (III)-thiol complexes. The remaining arsenic is mainly accumulated in the fraction containing cellular debris (~20%), with decreasing proportions accumulated in the metal-rich granules, organelles and heat-sensitive proteins fractions. A biological detoxified metal compartment including heat stable proteins and the fraction containing metal-rich granules is capable of binding arsenic coming into the cells at a constant rate under sublethal arsenic bioavailabilities. The remaining arsenic entering the cell is bound loosely into the cellular debris fraction, which can be subsequently released and diverted to an expanding detoxified pool. Our results suggest that a metal sensitive compartment comprising the cellular debris, enzymes and organelles fractions may be more representative of the toxic effects observed.",
Arsenic,1508531,"Comparative Genomic Analysis of Phylogenetically Closely-Related Hydrogenobaculum sp. from Yellowstone National Park Abstract: We describe the complete genome sequences of four closely related Hydrogenobaculum sp. isolates (&gt; 99.7% 16S rRNA gene identity) that were isolated from the outflow channel of Dragon Spring (DS), Norris Geyser Basin in Yellowstone National Park (YNP), WY, USA. The genomes range in size from 1,552,607 to 1,552,931 bp, contain 1667 to 1676 predicted genes, and are highly syntenic. There are subtle differences among the DS isolates, which as a group are different from Hydrogenobaculum sp. strain Y04AAS1 that was previously isolated from a geographically distinct YNP geothermal feature. Genes unique to the DS genomes encode arsenite (AsIII) oxidation, NADH/Ubiquinone/plastoquinone (complex I), NADH-ubiquinone oxidoreductase chain, a DNA photolyase, and elements of a Type II secretion system. Functions unique to strain Y04AAS1 include thiosulfate metabolism, nitrate respiration, and mercury resistance determinants. DS genomes contain seven CRISPR loci that are almost identical, but are different from the single CRISPR locus in strain Y04AAS1. Other DS x Y04AAS1 genome differences include average nucleotide identity (94.764%) and percentage conserved DNA (80.552%). Approximately half of the genes unique to Y04AAS1 are predicted to have been acquired via horizontal gene transfer. Fragment recruitment analysis and marker gene searches demonstrated that the DS metagenome was more similar to the DS genomes than to the Y04AAS1 genome, but that the DS community is likely comprised of a continuum of Hydrogenobaculum genotypes that span from the DS genomes described here to an Y04AAS1-like organism, which appears to represent a distinct ecotype relative to the DS genomes characterized.",
Arsenic,1936148,Physicochemical properties of non-living water hyacinth (Eichhornia crassipes) and lesser duckweed (Lemna minor) and their influence on the As(V) adsorption processes Abstract: ,
Arsenic,1019852,"Metabolism of arsenic by sheep chronically exposed to arsenosugars as a normal part of their diet. 1. Quantitative intake, uptake, and excretion Abstract: Information on the effects of long-term organoarsenical consumption by mammals is limited despite the fact that foodstuffs, especially seafood, often contain organoarsenicals at very high concentrations. Here we evaluate the intake, uptake, and excretion (urine and feces) of arsenic by sheep that live on North Ronaldsay in the Orkney Islands and naturally consume large amounts of arsenosugars through their major food source-seaweed. The sheep eat a broad variety of seaweed species, and arsenic concentrations were determined in all the species observed eaten by the sheep (5.7-74.0 mg kg(-1) dry mass). Because of preference and availability, they feed mostly on the seaweed species found to contain the highest arsenic concentrations: Laminaria digitata and Laminaria hyperborea (74 +/- 4 mg kg(-1) dry mass). To quantify the arsenic intake by the sheep, a feeding experiment reflecting natural conditions as close as possible was set up. In the feeding trial, the average daily intake of arsenic by 12 ewes was 35 +/- 6 mg (97% of water-extractable arsenic was present as arsenosugars) gained from feeding on the two brown algae. To test the possible influence of microflora on the metabolism of arsenosugars, six of the sheep were adapted to feeding on grass for 5 months before the start of the trial (control sheep), and the remaining six sheep were kept on their normal seaweed diet (wild sheep). No significant difference in seaweed/arsenic intake and arsenic excretion was found between the two groups of sheep. The arsenic excreted in the feces represents 13 +/- 10% (n = 12) of the total consumed, and on the assumption of that, the average urinary excretion is estimated to 86%.The main arsenic metabolite excreted in urine was dimethylarsinic acid (DMA(V)) (60 +/- 22%) and minor amounts of dimethylarsinoylethanol (DMAE), methylarsonic acid (MA(V)),tetramethylarsonium ion (TMA+), and arsenate (As(V)) together with seven unknown arsenic compounds were also excreted. The urinary arsenic excretion pattern showed a lag period (&gt;4 h) before significant quantities appeared in the urine, an excretion rate that peaked between 4 and 28 h after seaweed intake and a relatively slow half-life (17 h) after end of intake.",
Arsenic,1351364,Spectrophotometric determination of arsenic via nanogold formation in micellar medium Abstract: ,
Arsenic,2088560,"Heavy metal bioaccumulation in sediment, common reed, algae and blood worm from the Shoor River, Iran Abstract: Concentrations of 11 metals (cadmium, zinc, copper (Cu), vanadium (V), lead, magnesium (Mg), manganese, aluminum, iron (Fe), chromium (Cr), and nickel), and one metalloid (arsenic (As)) were measured in sediment, common reed (Phragmites australis), algae (Spirogyra sp.), and blood worm (Chironomus sp.) tissues of samples collected from the Shoor river. Samples were dried, acid digested, and the concentrations of metals were measured using inductively coupled plasma-optical emission spectrometer. A higher concentration of heavy metals was accumulated in Spirogyra and Chironomids than sediment and common reed. The highest rate of accumulation was found for Mg, V, Fe, As, Cu, and Cr. Spirogyra and Chironomids are capable of accumulating and thereby removing metals from polluted water bodies and are suitable for biomonitoring purposes.",
Arsenic,2149192,"Geogenic arsenic and other trace elements in the shallow hydrogeologic system of Southern Poopó Basin, Bolivian Altiplano Abstract: Environmental settings in the southern area of Lake Poopó in the Bolivian highlands, the Altiplano, have generated elevated amounts of arsenic (As) in the water. The area is characterised by a semiarid climate, slow hydrological flow and geologic formations of predominantly volcanic origin. The present study aimed at mapping the extent of the water contamination in the area and to investigate the geogenic sources and processes involved in the release of As to the groundwater. Ground- and surface-water samples were collected from 24 different sites, including drinking water wells and rivers, in the southern Poopó basin in two different field campaigns during the dry and rainy seasons. The results revealed variable levels of As in shallow drinking water wells and average concentration exceeding the WHO guidelines value. Arsenic concentrations range from below 5.2?g/L (the detection level) to 207?g/L and averages 72?g/L. Additionally, high boron (B) concentrations (average 1902?g/L), and high salinity are further serious concerns for deteriorating the groundwater quality and rendering it unsuitable for drinking. Groundwater is predominantly of the Na-Cl-HCO3 type or the Ca-Na-HCO3 type with neutral or slightly alkaline pH and oxidising character. While farmers are seriously concerned about the water scarcity, and on a few occasions about salinity, there are no concerns about As and B present at levels exceeding the WHO guidelines, and causing negative long term effects on human health. Sediment samples from two soil profiles and a river bed along with fourteen rock samples were also collected and analysed. Sequential extractions of the sediments together with the calculation of the mineral saturation indices indicate that iron oxides and hydroxides are the important secondary minerals phases which are important adsorbents for As. High pH values, and the competition of As with HCO3 and dissolved silica for the adsorption sites probably seems to be an important process for the mobilisation of As in the shallow groundwaters of the region. Continuous monitoring and expansion of monitoring systems are necessary prerequisites for better understanding of the pattern of As mobilisation in the Southern Poopó Basin.",
Arsenic,62195,"A morbid condition involving cardio-vascular, broncho-pulmonary, digestive and neural lesions in children and young adults after dietary arsenic exposure Abstract: An investigation on the relationship between dietary arsenic exposure and cardiovascular diseases was made. In Antofagasta Commune, northern Chile, since 1955 arsenic has polluted public drinking water. This environmental contamination is of geological origin. The concentration of arsenic in drinking water for the 1955-1970 period was 0.5980 ppm (weighted mean). In the period June 1970-March 1972, the concentration decreased to 0.0815 ppm (weighted mean), due to a Water Filtration Plant which started operating in May 1970. Greater Santiago showed 0.00 ppm of arsenic in drinking water. Amongst 10 autopsied patients (age range: 1 year 7 months to 18 years) with chronic arsenical dermatosis from Antofagasta Commune, 9 showed marked fibrous intimal thickening of the arterial wall and/or restricted lumen of the left coronary artery, 2 of these 9 also exhibiting myocardial infarction. Of the 10 patients, 7 developed cardiomegaly, which was related to chronic exposure to dietary arsenic. Two series of patients with myocardial infarction under 40 years of age, one from Antofagasta Commune (exposed to arsenic), the other from Greater Santiago (not exposed to arsenic) were compared. The Yates' corrected chi 2 value (1 d.f.) being 11.7776. The difference was statistically highly significant (P approximately equal to 0.0006018). Furthermore, in Antofagasta Commune, the number of cases (< 40 yr) which had myocardial infarction with chronic arsenical dermatosis were compared with the cases (< 40 yr) which showed myocardial infarction without chronic arsenical dermatosis. The Yates' corrected chi 2 value (1 d.f.) was 13.0395. A highly significant difference was detected (P approximately equal to 0.0003044). Children (0-15 yr)from the two cities were also compared.(ABSTRACT TRUNCATED AT 250 WORDS)",
Arsenic,2347589,"Co-occurrence profiles of trace elements in potable water systems: A case study Abstract: Potable water samples (N?=?74) from 19 zip code locations in a region of Greece were profiled for 13 trace elements composition using inductively coupled plasma mass spectrometry. The primary objective was to monitor the drinking water quality, while the primary focus was to find novel associations in trace elements occurrence that may further shed light on common links in their occurrence and fate in the pipe scales and corrosion products observed in urban drinking water distribution systems. Except for arsenic at two locations and in six samples, rest of the analyzed elements was below maximum contaminant levels, for which regulatory values are available. Further, we attempted to hierarchically cluster trace elements based on their covariances resulting in two groups; one with arsenic, antimony, zinc, cadmium, and copper and the second with the rest of the elements. The grouping trends were partially explained by elements' similar chemical activities in water, underscoring their potential for co-accumulation and co-mobilization phenomena from pipe scales into finished water. Profiling patterns of trace elements in finished water could be indicative of their load on pipe scales and corrosion products, with a corresponding risk of episodic contaminant release. Speculation was made on the role of disinfectants and disinfection byproducts in mobilizing chemically similar trace elements of human health interest from pipe scales to tap water. It is warranted that further studies may eventually prove useful to water regulators from incorporating the acquired knowledge in the drinking water safety plans.",
Arsenic,1508517,"Simultaneous removal of arsenate and arsenite by a nanostructured zirconium-manganese binary hydrous oxide: Behavior and mechanism Abstract: Arsenate and arsenite typically co-exist in groundwater. Arsenite is more toxic than arsenate, while it is more difficult to be removed than arsenate. In order to effectively remove arsenate and arsenite simultaneously from water solution, a nanostructured zirconium-manganese binary hydrous oxide was successfully developed in this study. The amorphous sorbent was aggregate of nanoparticles with a high surface area of 213m2g-1. Our sorption experiments showed that the nano-scale particles could effectively oxidize As(III) to As(V) and greatly remove both As(V) and As(III). The maximal adsorption capacities of As(V) and As(III) were 80 and 104mgg-1 at pH 5.0, respectively. As(V) uptake may be mainly achieved through replacement of hydroxyl groups and sulfate anions on the surface of the oxide and formation of inner complexes. The As(III) removal was essentially due to a sorption coupled with oxidation process; the MnO2 was mainly responsible for oxidization of As(III) to As(V) that was subsequently adsorbed onto ZrO2.",
Arsenic,1028757,"Interaction of selenium and arsenic with metallothionein: effect of vitamin B12 Abstract: The effects of selenium and arsenic on metallothionein (MT) levels were determined in vitamin B12-supplemented and depleted rats. The binding of selenium and arsenic to MT in vitro and in vivo was also investigated. Rats fed a vitamin B12-deficient diet had significant (p &lt; 0.05), higher levels of liver MT as compared to vitamin B12-supplemented rats. Rats fed 5-9 micrograms/g selenium as selenite or 50-150 micrograms/g arsenic as arsenite showed no significant increase of MT content in the liver. However, significant increases in MT levels in liver (p &lt; 0.01) and kidney (p &lt; 0.05) were seen when rats were injected with 1.5 mg selenium as selenite, and increase of liver MT levels (p &lt; 0.05) was shown when injected with 5 mg arsenic as arsenite/kg body weight. In comparison to zinc, injection of selenium or arsenic caused only a slight elevation of liver MT levels. Liver cytosolic Sephadex G-75 patterns of rats injected with both zinc and arsenic gave separate peaks for arsenic and zinc which suggest that in vivo arsenic binding to MT may be insignificant. Spectrophotometric absorption changes at 255 nm with various levels of selenium or arsenic additions to an MT solution were used to show that selenite gave a maximum absorption increase at a 1:1 molar ratio, but maximum absorption change occurred with arsenite at a molar ratio of 7:1.",
Arsenic,1337312,Draft Genome Sequence of Agrobacterium albertimagni Strain AOL15 Abstract: Agrobacterium albertimagni strain AOL15 is an alphaproteobacterium isolated from arsenite-oxidizing biofilms whose draft genome contains 5.1 Mb in 55 contigs with 61.2% GC content and includes a 21-gene arsenic gene island. This is the first available genome for this species and the second Agrobacterium arsenic gene island.,
Arsenic,1022517,"Induction of oxidative DNA damage by arsenite and its trivalent and pentavalent methylated metabolites in cultured human cells and isolated DNA Abstract: Even though a well-known human carcinogen the underlying mechanisms of arsenic carcinogenicity are still not fully understood. For arsenite, proposed mechanisms are the interference with DNA repair processes and an increase in reactive oxygen species. Even less is known about the genotoxic potentials of its methylated metabolites monomethylarsonous [MMA(III)] and dimethylarsinous [DMA(III)] acid, monomethylarsonic [MMA(V)] and dimethylarsinic [DMA(V)] acid. Within the present study we compared the induction of oxidative DNA damage by arsenite and its methylated metabolites in cultured human cells and in isolated PM2 DNA, by frequencies of DNA strand breaks and of lesions recognized by the bacterial formamidopyrimidine-DNA glycosylase (Fpg). Only DMA(III) (&gt; or =10 micro M) generated DNA strand breaks in isolated PM2 DNA. In HeLa S3 cells, short-term incubations (0.5-3 h) with doses as low as 10 nM arsenite induced high frequencies of Fpg-sensitive sites, whereas the induction of oxidative DNA damage after 18 h incubation was rather low. With respect to the methylated metabolites, both trivalent and pentavalent metabolites showed a pronounced induction of Fpg-sensitive sites in the nanomolar or micromolar concentration range, respectively, which was present after both short-term and long-term incubations. Furthermore MMA(III) and DMA(V) generated DNA strand breaks in a concentration-dependent manner. Taken together our results show that very low physiologically relevant doses of arsenite and the methylated metabolites induce high levels of oxidative DNA damage in cultured human cells. Thus, biomethylation of inorganic arsenic may be involved in inorganic arsenic-induced genotoxicity/carcinogenicity.",
Arsenic,1025872,"Use of RAPD to detect sodium arsenite-induced DNA damage in human lymphoblastoid cells Abstract: Inorganic arsenic is a known human carcinogen, yet its mechanism of action remains unclear. Our previous study showed that arsenite significantly induces oxidative DNA adducts and DNA-protein cross-links in several mammalian cell lines. In the present study, we used the random amplified polymorphic DNA (RAPD) assay to evaluate the possible target in the genomic DNA of human lymphoblastoid cells that were exposed to sodium arsenite. Treatment with both 10 and 80 microM arsenite for 4h induced significant changes in RAPD profiles compared with the control pattern. Two 10-mer RAPD primers (D11 and F1) produced the most distinguishable banding profiles between arsenite-treated and control genomic DNA. The sequencing of four arsenite-sensitive RAPD bands showed that the RB1CC1 and PACE4 genes might be the DNA targets of sodium arsenite treatment. We propose that arsenite may induce sequence- or gene-specific damage and then change the RAPD profile in human lymphoblastoid cells. The results of our study also show that RAPD combined with other techniques is a good tool for detecting alterations in genomic DNA and for the direct screening of new molecular markers related to arsenite-induced carcinogenesis.",
Arsenic,2347761,"Simultaneous removal of arsenate and fluoride from water by Al-Fe (hydr)oxides Abstract: Al-Fe (hydr)oxides with different Al/Fe molar ratios (4:1, 1:1, 1:4, 0:1) were prepared using a coprecipitat method and were then employed for simultaneous removal of arsenate and fluoride. The 4Al: Fe was superior to other adsorbents for removal of arsenate and fluoride in the pH range of 5.0-9.0. The adsorption capacity of the Al-Fe (hydr)oxides for arsenate and fluoride at pH 6.5 +/- 0.3 increased with increasing Al content in the adsorbents. The linear relationship between the amount of OH- released from the adsorbent and the amount of arsenate or fluoride adsorbent by 4Al: Fe indicated that the adsorption of arsenate and fluoride by Al-Fe (hydr)oxides was realized primarily through quantitative ligand exchange. Moreover, there was a very good correlation between the surface hydroxyl group densities of Al-Fe (hydr)oxides and their adsorption capacities for arsenate or fluoride. The highest adsorption capacity for arsenate and fluoride by 4Al : Fe is mainly ascribed to its highest surface hydroxyl group density besides its largest pH(pzc). The dosage of adsorbent necessary to remove arsenate and fluoride to meet the drinking water standard was mainly determined by the presence of fluoride since fluoride was generally present in groundwater at much higher concentration than arsenate.",
Arsenic,735094,"Primary large-cell neuroendocrine carcinoma of the scrotum Abstract: Neuroendocrine tumors (NETs) mostly develop from the neural crest cells but a few arise from neuroectoderm. They are common in the lungs and gastrointestinal tract but rare in the genitourinary tract. A 78-year-old man with no family history of malignant or hereditary diseases presented with a 3-month history of a rapidly growing asymptomatic scrotal nodule and swelling in the groin. He had a negative history of sexually transmitted disease and of trauma, fungal infection or chronic irritation in the scrotal area; there was no history of radiotherapy or exposure to chemicals or arsenic. Both the scrotal and groin lesions were excised with a minimum of 1.2 cm of normal skin. Examination of the specimen revealed a confined poorly differentiated large-cell neuroendocrine carcinoma with a metastasis to the inguinal lymph nodes. Three months after the excision we found a local recurrence. The recurrent tumor revealed tumor tissue concurrent with the primary lesion. To the best of our knowledge, there have been no previously published case reports on neuroendocrine tumor of the scrotum.",
Arsenic,1017711,"Real-time monitoring of arsenic filtration by granular ferric hydroxide Abstract: Contamination of drinking water by arsenic is a serious public health issue in many parts of the world. One recent approach to this problem has been to filter out arsenic by use of granular ferric hydroxide (GFH), an adsorbent developed specifically for the selective removal of arsenic from water. Previous studies have documented the efficiency and high treatment capacity of this approach. We present a novel X-ray fluorescence method to monitor the accumulation of arsenic within a specially designed GFH column, as both a function of time (or water volume) and location along the column. Using a miniature X-ray tube and silicon PiN diode detector, X-ray fluorescence is used to detect characteristic X-rays of arsenic excited from within the GFH. Trials were performed using a water flow rate of approximately 1.5 L per hour, with an added arsenic concentration of approximately 1000 microg per litre. In this paper, trial results are presented and potential applications described.",
Arsenic,627522,"Arsenite inhibits mitotic division and perturbs spindle dynamics in HeLa S3 cells Abstract: Arsenical compounds, known to be human carcinogens, were shown to disturb cell cycle progression and induce cytogenetic alterations in a variety of cell systems. We report here that a 24 h treatment of arsenite induced mitotic accumulation in human cell lines. HeLa S3 and KB cells were most susceptible: 35% of the total cell population was arrested at the mitotic stage after treatment with 5 microM sodium arsenite in HeLa S3 cells and after 10 microM in KB cells. Under a microscope, we observed abnormal mitotic figures in arsenite-arrested mitotic cells, including deranged chromosome congression, elongated polar distance of mitotic spindle, and enhanced microtubule immunofluorescence. The spindle microtubules of arsenite-arrested mitotic cells were more resistant to nocodazole-induced dissolution than those of control mitotic cells. According to turbidity assay, arsenite at concentrations below 100 microM significantly enhanced polymerization of tubulins. Since spindle dynamics play a crucial role in mitotic progression, our results suggest that arsenite-induced mitotic arrest may be due to arsenite's effects on attenuation of spindle dynamics.",
Arsenic,1519206,"Po-210 Activity and Concentrations of Selected Trace Elements (As, Cd, Cu, Hg, Pb, Zn) in the Muscle Tissue of Tunas Thunnus albacares and Katsuwonus pelamis from the Eastern Pacific Ocean Abstract: ",
Arsenic,1340081,"Abiotic oxidation of Mn(II) and its effect on the oxidation of As(III) in the presence of nano-hematite Abstract: Manganese (hydr)oxides (MnO(x)) is a powerful oxidant in the oxidation of As(III) in natural environment. Under some circumstances, Mn(II) can be oxidized to MnO(x) which in turn accelerates the oxidation of As(III). However, to the best of our knowledge, little is known regarding how Mn(II) affects the oxidation of both the dissolved and the adsorbed As(III) in aquatic environments. In this study, effects of abiotic oxidation of Mn(II) on the oxidation of As(III) were investigated. Kinetic results as well as TEM and XRD analyses confirmed the formation of amorphous MnO(x) after sorption of Mn(II) on hematite nano-particles under oxic conditions. Mn(II) was oxidized to Mn(III) and then to Mn(IV), and this process was dependent upon pH and Mn(II) concentrations. The newly formed MnO(x) played an important role in the further oxidation of the dissolved and the adsorbed As(III) on hematite, and the oxidation rate of As(III) increased with the rising Mn(II) concentrations. As the adsorbed As(III) was oxidized to As(V), a fraction of As(V) was released into the solution, which increased the mobility of As. The present study reveals that abiotic oxidation of Mn(II) affects the oxidation of As(III) in aquatic environment.",
Arsenic,1016613,"Abnormal current perception thresholds measured by neurometer among residents in Blackfoot disease-hyperendemic villages in Taiwan Abstract: This study evaluated the possible existence of subclinical sensory nerve defects in residents of blackfoot disease (BFD)-hyperendemic villages in Taiwan characterized by long-term arsenic exposure from drinking water. Eighty-five seemingly normal subjects living in BFD villages and 75 external normal controls without exposure were recruited. All subjects were 30-75 years old, without possible causes of peripheral neuropathy and suffered from no symptoms of peripheral neuropathy. Current perception threshold (CPT) was measured by Neurometer at the trigeminal, median and superficial peroneal nerves with frequencies of 5, 250 and 2000 Hz. Results showed that the two groups were comparable in age, sex, body height and body weight. However, BFD residents had significantly 1.28-2.23-fold higher CPT than normal controls for all frequencies at the 3 nerves. If the mean values + 3 standard deviations (S.D.) derived from normal controls were used as cutoff points for defining abnormalities, 36 of the 85 (42.4%) residents in the BFD villages had at least one abnormal measurement. Site and frequency preferences were noted in the abnormal CPT of the BFD residents. Longer nerves (superficial peroneal and median nerves) were involved more commonly than shorter one (trigeminal); and lower frequencies (5 and 250 Hz) were more commonly involved than the higher one (2000 Hz). Stepwise regression analyses consistently showed that residency in BFD villages was significantly associated with higher CPT values after adjusting for age, sex, body height and body weight. In conclusion, abnormal CPT was observed in seemingly normal subjects without clinical neuropathy in the arseniasis-hyperendemic villages in Taiwan.",
Arsenic,871991,"Sodium arsenite-induced alteration in hepatocyte function of rat with special emphasis on superoxide dismutase expression pathway and its prevention by mushroom lectin Abstract: This study was accomplished to exemplify the possible protective role of ascorbic acid and mushroom lectin against arsenic-induced cytotoxicity and impairment of superoxide dismutase (SOD) production pathway in hepatocytes of rat. Hepatocytes were isolated from rat and treated with sodium arsenite (AS), arsenic plus ascorbic acid (AS + AA) and arsenic plus mushroom lectin (AS + ML). A placebo control was also included. Arsenic treatment resulted in the depletion of cell proliferation, phagocytic activity (nitro blue tetrazolium index) and superoxide dismutase (SOD) activity, relative mRNA expression of superoxide dismutase 2 (SOD(2)) and enhanced production of nitric oxide (NO). Ascorbic acid, a standard antioxidant, could normalize cellular perturbation and SOD production pathway relating to gene expression, whereas partially purified Pleurotus florida lectin (PFL), an edible mushroom containing protein complex, maintained cellular activity and prevented stress by normalizing phagocytic (NBT index) and SOD activities vis-à-vis relative gene expression. It could further defend NO production of hepatocytes. Mushroom lectin strongly prevented sodium arsenite-induced damage of SOD production pathway in hepatocytes, and its effect was also comparable to a standard antioxidant, i.e. ascorbic acid.",
Arsenic,628007,"Arsenic exposure accelerates atherogenesis in apolipoprotein E(-/-) mice Abstract: Epidemiologic studies have shown an association between elevated arsenic levels in drinking water and an increased risk of atherosclerosis and vascular diseases. The studies presented here were performed to evaluate the atherogenic potential of arsenic using a well-established and controlled animal model of human atherosclerosis, mice deficient in apolipoprotein E (ApoE), and in vitro systems including primary human vascular cells. Wild-type and ApoE-deficient mice were exposed to 20 or 100 microg/mL sodium arsenite in drinking water for 24 weeks. As assessed morphometrically, the size of grossly discernible lesions covering the intimal area of aorta were increased significantly in arsenic-treated ApoE-deficient mice compared with nontreated transgenic mice. This effect was not associated with increased levels of serum cholesterol but was accompanied by an accumulation of arsenic in the vessel wall. Introduction of cocoa butter into the diet for 2 weeks resulted in higher serum cholesterol levels and only slight increases in the lesion size in control or arsenic-exposed ApoE-deficient mice. There were no lesions observed in the wild-type C57BL6 mice, resistant to atherosclerosis, whether they received arsenic or control drinking water. In vitro studies, including primary aorta endothelial or smooth muscle cells, were conducted to evaluate whether arsenic induces cellular mechanisms relevant to atherogenesis such as endothelial dysfunction, lipid oxidation, and smooth muscle cell proliferation. Arsenic treatment does not modulate endothelial cell-mediated lipid oxidation or smooth muscle cell proliferation but induced the expression of genes coding inflammatory mediators, including interleukin-8. Induction of endothelial inflammatory activity may play a role in arsenic-related vascular effects.",
Arsenic,2337208,"Natural attenuation of coal combustion waste in river sediments Abstract: The weathering of coal combustion products (CCPs) in a lotic environment was assessed following the Tennessee Valley Authority (Kingston, TN) fly ash release of 2008 into surrounding rivers. Sampled materials included stockpiled ash and sediment collected from 180 to 880 days following the release. Total recoverable concentrations of heavy metals and metalloids in sediment were measured, and percent ash was estimated visually or quantified by particle counts. Arsenic and selenium in sediment were positively correlated with percent ash. For samples collected 180 days after the release, total concentrations of trace elements downstream of the release were greater than reference levels but less than concentrations measured in stockpiled ash. Total concentrations of trace elements remained elevated in ash-laden sediment after almost 2.5 years. A sequential extraction procedure (SEP) was used to speciate selected fractions of arsenic, copper, lead, nickel, and selenium in decreasing order of bioavailability. Concentrations of trace elements in sequentially extracted fractions were one to two orders of magnitude lower than total recoverable trace elements. The bulk of sequentially extractable trace elements was associated with iron-manganese oxides, the least bioavailable fraction of those measured. By 780 days, trace element concentrations in the SEP fractions approached reference concentrations in the more bioavailable water soluble, ion exchangeable, and carbonate-bound fractions. For each trace element, the percentage composition of the bioavailable fractions relative to the total concentration was calculated. These SEP indices were summed and shown to significantly decrease over time. These results document the natural attenuation of leachable trace elements in CCPs in river sediment as a result of the loss of bioavailable trace elements over time.",
Arsenic,628636,"Involvement of hydrogen peroxide in the differentiation and apoptosis of preosteoclastic cells exposed to arsenite Abstract: Long-term exposure to sodium arsenite (AsO2) promotes the development of various cancers. Paradoxically, arsenic also induces pro-myelomonocytic leukemia cell differentiation, and at higher concentrations, apoptosis. The present study investigated the effects of AsO2 on preosteoclasts. When treated with 2.5–5 ?M AsO2, RAW264.7 cells underwent osteoclast differentiation as evidenced by an increase in the number of multinucleate cells expressing tartrate resistant acid phosphatase (TRAP). The appearance of these phenotypic markers was preceded by a low level increase in extracellular production of H2O2 and was prevented by the addition of catalase (4.5 ?g/ml), an enzyme that removes H2O2. Only at high concentrations (10–25 ?M) of AsO2 was a significant loss of cell viability and a high level increase in H2O2 production (1.5 ?M) observed. Apoptosis was blocked by pretreatment with diphenylene iodonium chloride (2 ?M), a NAD(P)H-flavoprotein inhibitor, suggesting the involvement of NADPH-oxidase. The data show that AsO2, dose-dependently, stimulates increasing amounts of H2O2 production. Moreover, at concentrations found in tissues of individuals exposed to geochemical AsO2, osteoclasts underwent an H2O2-dependent differentiation. Therefore, chronic exposure to low-level amounts of AsO2 could result in increased bone resorption and contribute to bone related pathologies.",
Arsenic,1015995,"Exposure to moderate arsenic concentrations increases atherosclerosis in ApoE-/- mouse model Abstract: Arsenic is a widespread environmental contaminant to which millions of people are exposed worldwide. Exposure to arsenic is epidemiologically linked to increased cardiovascular disease, such as atherosclerosis. However, the effects of moderate concentrations of arsenic on atherosclerosis formation are unknown. Therefore, we utilized an in vivo ApoE(-/-) mouse model to assess the effects of chronic moderate exposure to arsenic on plaque formation and composition in order to facilitate mechanistic investigations. Mice exposed to 200 ppb arsenic developed atherosclerotic lesions, a lower exposure than previously reported. In addition, arsenic modified the plaque content, rendering them potentially less stable and consequently, potentially more dangerous. Moreover, we observed that the lower exposure concentration was more atherogenic than the higher concentration. Arsenic-enhanced lesions correlated with several proatherogenic molecular changes, including decreased liver X receptor (LXR) target gene expression and increased proinflammatory cytokines. Significantly, our observations suggest that chronic moderate arsenic exposure may be a greater cardiovascular health risk than previously anticipated.",
Arsenic,628472,"Prevalence of non-insulin-dependent diabetes mellitus and related vascular diseases in southwestern arseniasis-endemic and nonendemic areas in Taiwan Abstract: There is evidence indicating that ingestion of arsenic may predispose the development of diabetes mellitus in arsenic-endemic areas in Taiwan. However, the prevalence of diabetes and related vascular diseases in the entire southwestern arseniasis-endemic and nonendemic areas remains to be elucidated. We used the National Health Insurance Database for 1999-2000 to derive the prevalence of non-insulin-dependent diabetes and related vascular diseases by age and sex among residents in southwestern arseniasis-endemic and nonendemic areas in Taiwan. The study included 66,667 residents living in endemic areas and 639,667 in nonendemic areas, all greater than or equal to 25 years of age. The status of diabetes and vascular diseases was ascertained through disease diagnosis and treatment prescription included in the reimbursement claims of clinics and hospitals. The prevalence of non-insulin-dependent diabetes, age- and gender-adjusted to the general population in Taiwan, was 7.5% (95% confidence interval, 7.4-7.7%) in the arseniasis-endemic areas and 3.5% (3.5-3.6%) in the nonendemic areas. Among both diabetics and nondiabetics, higher prevalence of microvascular and macrovascular diseases was observed in arseniasis-endemic than in the nonendemic areas. Age- and gender-adjusted prevalence of microvascular disease in endemic and nonendemic areas was 20.0% and 6.0%, respectively, for diabetics, and 8.6% and 1.0%, respectively, for nondiabetics. The corresponding prevalence of macrovascular disease was 25.3% and 13.7% for diabetics, and 12.3% and 5.5% for nondiabetics. Arsenic has been suggested to increase the risk of non-insulin-dependent diabetes mellitus and its related micro- and macrovascular diseases.",
Arsenic,1031389,"Biomonitoring of urinary metals in a population living in the vicinity of industrial sources: a comparison with the general population of Andalusia, Spain Abstract: The Ria of Huelva (south-west Spain) is one of the most polluted fluvial-estuarine systems in the world. Industrial activity delivers huge amounts of pollutants to the local environment, particularly heavy metals and arsenic. Here we aimed to determine urinary levels of As, Cd, Cr, Cu and Ni in a representative sample (n=857) of adults living in the Ria of Huelva. Levels were compared to those from a representative sample of 861 adults of the general urban population of Andalusia (southern Spain) and multiple regression models were developed to identify individual factors associated with urinary levels of these elements. Arsenic levels were significantly higher in the Ria of Huelva as compared to other Andalusian cities, whereas Cd and Ni levels were significantly lower. Despite these differences, levels in both groups were similar to the reference values reported in previous studies for general population. Age, gender, diet and lifestyle were the major factors contributing to the interindividual variation in urinary metals. In conclusion, despite living in a highly polluted area, the population of the Ria of Huelva failed to show higher urinary levels of the studied metals as compared to a reference urban population of the same region.",
Arsenic,1378659,"Inorganic And Methylated Trivalent Arsenicals Suppress Adipocyte Differentiation Abstract: Chronic exposures to inorganic arsenic (iAs) have been associated with disruptions in glucose metabolism and symptoms consistent with non-insulin-dependent (type-2) diabetes mellitus. Previous work found that arsenite (iAsIII) and its methylated trivalent metabolites, methylarsonous acid (MAsIII), and dimethylarsinous acid (DMAsIII), inhibit insulin stimulated glucose uptake by differentiated adipocytes. In addition, iAsIII has been shown to interfere with adipocyte differentiation, suggesting that multiple mechanisms may underlie the diabetogenic effects of chronic exposures to iAs. This study examines the role of methylated metabolites of iAs in the inhibition of adipocyte differentiation. Confluent murine 3T3-L1 preadipocytes were exposed for 7 days to non-toxic concentrations of iAsIII (1 or 10 uM), MAsIII (0.1 or 0.5 uM) and DMAsIII (0.1, 0.5, or 1 uM) beginning 12 hours prior to or 24 hours after the induction of differentiation by a mixture of 3- isobutyl-1-methylxanthine, dexamethasone, and insulin (MDI). The intracellular lipid content and glucose transporter-4 (GLUT4) expression were measured as markers of adipocyte differentiation. In general, the exposures beginning after the MDI treatment were less effective in inhibiting adipocyte differentiation than those starting prior to MDI treatment. When started after the MDI treatment the exposures to 1 uM iAsIII, 0.5 uM MAsIII and 1 uM DMAsIII inhibited adipocyte differentiation by 15%, 30%, and 40%, respectively. The same exposures beginning prior to the MDI treatment decreased the extent of differentiation by about 50%. These data suggest that trivalent arsenicals disrupt the adipocyte differentiation program at multiple points, possibly through different mechanisms. Adipose tissue plays a critical role in the regulation of whole body glucose homeostasis. The suppression of adipocyte differentiation by trivalent arsenicals generated in the course of in vivo metabolism of iAs may contribute to the diabetogenic effects of chronic exposure to iAs.",
Arsenic,1022078,"Effects of inorganic and organic arsenic compounds on growth and apoptosis of human T-lymphoblastoid leukemia cells Abstract: <strong>BACKGROUND/AIM: </strong>To investigate the effects of inorganic and organic arsenic compounds on human T-lymphoblastoid leukemia cells.<br /><br /><strong>MATERIALS AND METHODS: </strong>Cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5¬diphenyltetrazolium bromide (MTT) assay. Apoptotic cell morphology was examined by cell staining with Hoechst 33342. Cellular caspase-3/7 activities were measured after arsenic treatment.<br /><br /><strong>RESULTS: </strong>The inhibitory concentration by 50% (IC(50)) values of As(2)O(3) towards MOLT-4 and daunorubicin- resistant MOLT-4/DNR cell proliferation were 0.87 and 0.92 ?M, while the values for arsenic acid were 69.1 and 116.6 ?M, respectively. These arsenic compounds also inhibited mitogen-induced proliferation of human peripheral blood mononuclear cells. Six organic arsenic compounds did not inhibit leukemia cell proliferation. As(2)O(3) and arsenic acid induced apoptotic cell morphology and increased caspase-3/7 activity in the leukemia cells. Ascorbic acid and buthionine sulfoxide enhanced, while N-acetyl-L-cysteine abated, the suppressive effects of inorganic arsenic compounds on leukemia cell proliferation.<br /><br /><strong>CONCLUSION: </strong>As(2)O(3) and arsenic acid inhibit proliferation and induce apoptosis in MOLT-4 and daunorubicine-resistant MOLT-4/DNR cells via glutathione-depletion and subsequent caspase-3/7 activation. Organic arsenic compounds have no inhibitory activity on the leukemia cell proliferation. Inorganic arsenic compounds are suggested as useful agents for treatment of T-lymphoblastoid leukemia.",
Arsenic,2298725,"The reaction of arsenite with proteins relies on solution conditions Abstract: Arsenic is a biologically interesting element with both antitumor and carcinogenic effects. Zinc finger proteins (ZFPs) have been confirmed to be the cellular targets of arsenite; however, arsenite inhibits ZFPs much less efficiently in vitro than in vivo. The molecular mechanism of this difference is unknown. In this work, we found that the reaction of arsenite with ZFPs relies on the presence of small biomolecules such as glutathione (GSH), histidine, and cysteine (Cys). The weak acidity also enhances the reaction. Further study shows that the coordination of zinc is much more susceptible than that of arsenic to these solution conditions, which enhance the competition of arsenic. Notably, different from C3H-type ZFPs, the C2H2-type ZFPs are more significantly influenced by the presence of thiol-containing molecules in the reaction. GSH and Cys can facilitate the reaction by participation of the coordination to As(III) together with C2H2-type ZFPs. Consequently, the reactions are promoted both thermodynamically and kinetically via the formation of ternary complexes GSH-As-ZFP or Cys-As-ZFP. These results indicate that the reactions between arsenite and proteins are considerably modulated by environments such as the small biomolecules and the acidity of the solution. This finding clarifies the discrepancy observed in the reactions of arsenite in vitro versus in cells, and provides an insight into the molecular mechanism of arsenite.",
Arsenic,528041,"The production of speiss (iron arsenide) during the Early Bronze Age in Iran Abstract: In this paper, analyses of some unusual slag samples from the prehistoric site of Tepe Hissar in north-eastern Iran are presented. These slags are the remains of a five-thousand-year-old pyrotechnological process that produced speiss, a quasi-metallic material usually formed as an accidental by-product of copper or lead smelting. We argue that the ""speiss slags"" from Tepe Hissar suggest the intentional production of iron-arsenic alloy (""speiss"") in prehistory. Why the Tepe Hissar metalworkers produced speiss is a question that requires further investigation, but our preliminary assessment suggests that it was to provide arsenic as an alloying component for arsenical copper, the preferred copper alloy during much of the Early Bronze Age in Iran. and widely used across the ancient world. This recognition significantly advances our understanding of the early stages of metallurgy in the Old World. (C) 2008 Elsevier Ltd. All rights reserved.",
Arsenic,2064282,"Systematic review and meta-analysis of intrauterine adhesions after miscarriage: Prevalence, risk factors and long-term reproductive outcome Abstract: BACKGROUND Approximately 15–20% of all clinically confirmed pregnancies end in a miscarriage. Intrauterine adhesions (IUAs) are a possible complication after miscarriage, but their prevalence and the contribution of possible risk factors have not been elucidated yet. In addition, the long-term reproductive outcome in relation to IUAs has to be elucidated. METHODS We systematically searched the literature for studies that prospectively assessed the prevalence and extent of IUAs in women who suffered a miscarriage. To be included, women diagnosed with a current miscarriage had to be systematically evaluated within 12 months by hysteroscopy after either spontaneous expulsion or medical or surgical treatment. Studies that included women with a history of recurrent miscarriage only or that evaluated the IUAs after elective abortion or beyond 12 months after the last miscarriage were not included. Subsequently, long-term reproductive outcomes after expectant (conservative), medical or surgical management were assessed in women with and without post-miscarriage IUAs. RESULTS We included 10 prospective studies reporting on 912 women with hysteroscopic evaluation within 12 months of miscarriage and 8 prospective studies, including 1770 women, reporting long-term reproductive outcome. IUAs were detected in 183 women, resulting in a pooled prevalence of 19.1% [95% confidence interval (CI): 12.8–27.5%]. The extent of IUAs was reported in 124 women (67.8%) and was mild, moderate and severe respectively in 58.1, 28.2 and 13.7% of cases. Relative to women with one miscarriage, women with two or three or more miscarriages showed an increased risk of IUAs by a pooled OR of 1.41 and 2.1, respectively. The number of dilatation and curettage (D&C) procedures seemed to be the main driver behind these associations. A total of 150 congenital and acquired intrauterine abnormalities were encountered in 675 women, resulting in a pooled prevalence of 22.4% (95% CI: 16.3–29.9%). Similar reproductive outcomes were reported subsequent to conservative, medical or surgical management for miscarriage, although the numbers of studies and of included women were limited. No studies reported long-term reproductive outcomes following post-miscarriage IUAs. CONCLUSIONS IUAs are frequently encountered, in one in five women after miscarriage. In more than half of these, the severity and extent of the adhesions was mild, with unknown clinical relevance. Recurrent miscarriages and D&C procedures were identified as risk factors for adhesion formation. Congenital and acquired intrauterine abnormalities such as polyps or fibroids were frequently identified. There were no studies reporting on the link between IUAs and long-term reproductive outcome after miscarriage, while similar pregnancy outcomes were reported subsequent to conservative, medical or surgical management. Although this review does not allow strong clinical conclusions on treatment management, it signals an important clinical problem. Treatment strategies are proposed to minimize the number of D&C in an attempt to reduce IUAs.",
Arsenic,2347611,"Identification of indicators of groundwater quality formation process using a zoning model Abstract: Drinking water safety is a world-wide focus. In Yinchuan Plain of western China, groundwater is mostly saline water, and it has generated many problems for the life of local residents. Yinchuan Plain exhibits differences from the mountain area to the plain in terrain and elevation, and landforms and scales. Such differences resulted in hydro-geological water storage structures with different water yield properties and permeabilities of the aquifers. These water storage structures are the places where the groundwater moves and is retained, as well as where the air-water-rock interaction and the migration and differentiation between substances in the water take place. With the and climate and intense irrigation in Yinchuan Plain, the hydro-chemical features of the groundwater exhibit distinct zonation. To explore the formative mechanism of the groundwater quality in Yinchuan Plain, a zoning model for the formation of groundwater quality is established in three layers, the first layer shows the geological and hydrogeological conditions that express the landform and landscape, geological age, lithology, and hydrodynamic features of the studied area. The second layer indicates the zonation of the formation of groundwater quality. According to the major hydro-geochemical actions, the plain is divided from west to east into lixiviation, evaporation, and evaporation-mixing zones. The third layer contains the hydrodynamic features that express the hydro-chemical type, salinity, and the contents of the major ions as well as trace elements fluorine and arsenic. The features of each zone are quantitatively expressed with thermodynamic, hydrodynamic, and hydro-chemical indicators. (C) 2014 Elsevier B.V. All rights reserved.",
Arsenic,1509330,Functionalized poly(vinyl alcohol) based nanofibers for the removal of arsenic from water Abstract: ,
Arsenic,2345835,"Metals and metalloids in primary gold mining districts of Western Bolivia: anthropogenic and natural sources Abstract: Topsoil and subsoil samples located adjacent and distant from the mining operations sites were collected. Most total metals showed no significant differences between topsoil and subsoil or proximity, suggesting that they derive from endogenous parent material. There was an increment in Hg in topsoils adjacent to the mining operation sites, indicating a deposition of Hg from the amalgamation areas. Higher values of total, extractable and soluble As were observed adjacent to the mining operation sites, probably related to the presence of residues, rich in arsenopyrite. Organic matter and clay contents control the concentrations of EDTA-extractable Cd and Zn, while soil acidity was associated with the behaviour of As, Hg and Cu. In contrast the concentration of EDTA-extractable Pb was directly affected by its total concentration. In general, soluble metals were highly independent, without significant correlations with any soil physical and chemical properties.",
Arsenic,1519027,"Randomized controlled study of the T-type calcium channel antagonist MK-8998 for the treatment of acute psychosis in patients with schizophrenia Abstract: OBJECTIVE: This study aimed to evaluate whether the T-type calcium channel antagonist MK-8998 was effective in treating acute psychosis in patients with schizophrenia.<br /><br /><strong>METHODS: </strong>This was a randomized, double-blind, parallel-group study. After a placebo lead-in, acutely psychotic inpatients with schizophrenia were randomized to 4?weeks of MK-8998 12/16?mg daily (N?=?86), olanzapine 10/15?mg daily (N?=?47), or placebo (N?=?83). The primary efficacy measure was score on the Positive and Negative Syndrome Scale (PANSS).<br /><br /><strong>RESULTS: </strong>Out of 216 randomized patients, 158 completed the 4-week study: MK-8998?=?58 (67.4%), olanzapine?=?38 (80.9%), and placebo?=?62 (74.7%). The mean changes from baseline in PANSS score at week 4 for MK-8998 and olanzapine were not significantly different from placebo: MK-8998-placebo difference?=?-0.6 [95% confidence interval (CI): -7.0, 5.8], p?=?0.9; olanzapine-placebo difference?=?-4.3 [95% CI: -11.7, 3.1), p?=?0.3. A responder rate analysis (?20% improvement from baseline in PANSS score) suggested an advantage of olanzapine over placebo (odds ratio?=?2.20 [95% CI: 0.95, 5.09], p?=?0.07) but no effect of MK-8998 over placebo (odds ratio?=?1.28 [95% CI: 0.62, 2.64], p?=?0.5). Treatments were generally well tolerated, but more patients reported adverse events for MK-8998 (47.7%) and olanzapine (48.9%) than placebo (37.3%).<br /><br /><strong>CONCLUSIONS: </strong>MK-8998 was not effective in treating acutely psychotic inpatients with schizophrenia, as measured by PANSS score at week 4. Because of the limited efficacy of the active comparator, we cannot exclude the possibility that T-type calcium channel antagonists could prove to be effective in schizophrenia. Copyright © 2013 John Wiley &amp; Sons, Ltd.",
Arsenic,1252477,Dimethylarsenic acid induces tetraploids in Chinese hamster cells Abstract: The genotoxicity of nine organic and three inorganic arsenic (7440382) compounds was examined in cultured Chinese-hamster-cells. V79-cells were incubated with 50 or 100 microliters of various concentrations of the test compounds for 8 hours at 37 degrees-C; mitotic indices were determined by counting metaphases in 500 cells. Chromosomes exposed to the test compounds were stained in order to observe the chromosome numbers in a metaphase twice divided. The number of chromosomes in the V79-cells ranged from 20 to 25; metaphases which had 40 to 50 chromosomes were thus considered tetraploid cells. Observation of the metaphases in the sister chromatid exchange test revealed that only dimethylarsenic-acid (75605) at 0 to 250 micrograms per milliliter induced tetraploids and mitotic arrest. Tetraploid cells appeared to have low cell division ability or a slower cell cycle than diploid cells. The mitogenesis of human lymphocytes was also studied. Results suggested that dimethylarsenic-acid directly inhibited cell division. The authors conclude that dimethylarsenic-acid induced tetraploid may be an important part of arsenic genotoxicity. This compound may be the ultimate carcinogen of arsenic,
Arsenic,2149314,Minerals Abstract: ,
Arsenic,628705,"Long-term arsenic exposure and ischemic heart disease in arseniasis-hyperendemic villages in Taiwan Abstract: The association between long-term arsenic exposure and peripheral vascular disease has been well documented in our previous epidemiologic studies. The purpose of this study was to evaluate whether long-term arsenic exposure could be associated with ischemic heart disease (IHD). A total of 462 subjects living in the blackfoot disease-hyperendemic villages along the southwestern coast of Taiwan and characterized by long-term arsenic exposure from drinking artesian well water was studied. The subjects were recruited from an epidemiologic cohort who participated in a health examination. IHD was diagnosed by coding the resting electrocardiograms with the Minnesota code. History of arsenic exposure was estimated through information obtained from a personal interview according to a structured questionnaire and the arsenic content in artesian well water of the villages. Cumulative arsenic exposure (CAE) was calculated as the sum of the products multiplying the arsenic concentration in artesian well water (mg/l) by the duration of drinking the water (years) in consecutive periods of living in the different villages. Among the subjects, 78 cases (16.9%) were diagnosed as having IHD. The prevalence rates of IHD for the age groups of 30–39, 40–49, 50–59, and ?60 years were 4.9, 7.5, 16.8, and 30.7%, respectively (P<0.001). For those with CAE of 0, 0.1–14.9 and ?15 mg/l-years, the prevalence rates of IHD were 5.2, 10.9 and 24.1%, respectively (P<0.001). The odds ratios (95% confidence intervals) for IHD were 1.60 (0.48, 5.34), and 3.60 (1.11, 11.65), respectively, for those with CAE of 0.1–14.9 and ?15.0 mg/l-years, when compared with those lacking drinking water exposure to arsenic after multivariate adjustment. It is concluded that IHD in the arseniasis-hyperendemic villages in Taiwan was associated with long-term arsenic exposure.",
Arsenic,628827,"Monomethylarsonous acid (MMA(III)) and arsenite: LD(50) in hamsters and in vitro inhibition of pyruvate dehydrogenase Abstract: Monomethylarsonous acid (MMA(III)), a metabolite of inorganic arsenic, has received very little attention from investigators of arsenic metabolism in humans. MMA(III), like sodium arsenite, contains arsenic in the +3 oxidation state. Although we have previously demonstrated that it is more toxic than arsenite in cultured Chang human hepatocytes, there are no data showing in vivo toxicity of MMA(III). When MMA(III) or sodium arsenite was administered intraperitoneally to hamsters, the LD(50)s were 29.3 and 112.0 micromol/kg of body wt, respectively. In addition, inhibition of hamster kidney or purified porcine heart pyruvate dehydrogenase (PDH) activity by MMA(III) or arsenite was determined. To inhibit hamster kidney PDH activity by 50%, the concentrations (mean +/- SE) of MMA(III) as methylarsine oxide, MMA(III) as diiodomethylarsine, and arsenite were 59.9 +/- 6.5, 62.0 +/- 1.8, and 115.7 +/- 2.3 microM, respectively. To inhibit activity of purified porcine heart PDH activity by 50%, the concentrations (mean +/- SE) of MMA(III) as methylarsine oxide and arsenite were 17.6 +/- 4.1 and 106.1 +/- 19.8 microM, respectively. These data demonstrate that MMA(III) is more toxic than inorganic arsenite, both in vivo and in vitro, and call into question the hypothesis that methylation of inorganic arsenic is a detoxication process.",
Arsenic,1357493,"Modified electrical heating system for hydride generation atomic absorption spectrometry and elaboration of a digestion method for the determination of arsenic and selenium in biological materials Abstract: A modified electrical heating system was developed for hydride generation atomic absorption spectrometry, and a microwave digestion method was developed for the determination of arsenic (7440382) and selenium (7782492). An electric heating block was developed which was equipped with a T-shaped quartz tube with open ends. The heating block permitted a rapid and convenient change of the quartz tube in order to clean and condition its surface. High and constant measurement sensitivity was provided by frequent conditioning. The microwave digestion procedure used was simple and inexpensive. Analysis of organic reference materials was used to test the method. The results proved appropriate for trace concentrations of selenium and arsenic. The sensitivity of arsenic and selenium determinations could be increased considerably by rinsing the quartz cell with 40% hydrofluoric-acid for about 15 minutes. The detection limit of the method for both elements was 0.3 nanograms absolute in a 15 milliliter sample volume or 0.02 micrograms/liter.",
Arsenic,1355896,"Expression of P53, P21 in human lung adenocarcinoma A549 cell strains under hypoxia conditions and the effect of TSA on their expression Abstract: This paper was designed to investigate the expression of p53, p21 of A549 cell strains under hypoxic condition and the effect of trichostatin A (TSA), the inhibitor of histone deacetylasel (HDAC1) on their expression. The authors designed 1 normoxia group (control group) and 6 hypoxia groups (experimental group): hypoxia 6 h group (A), TSA+hypoxia 6 h (B), hypoxia 12 h group (C), hypoxia 24 h group (D), TSA+hypoxia 24 h (E), hypoxia 48 h group (F). The expression of HDAC1 in A549 cells was examined by using Western blot and the expression of p53, p21 in A549 cells and the effect of TSA on them were determined by using immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). The A value expressed by HDAC1 in A549 cell strains was 138+/-11 in the control group, 78+/-4, 86+/-5, 124+/-3, 120+/-9 in experimental groups A, C, D, F, respectively. The A value of the expression of the protein and mRNA of p53 in A549 cell strains were 0.12+/-0.02, 0.62+/-0.02 in the control group, 0.10+/-0.03, 0.32 +/-0.03; 0.11+/-0.01, 0.33+/-0.02; 0.13+/-0.03, 0.58+/-0.01; 0.12+/-0.02, 0.56+/-0.02 in experimental group A, B, D, E, respectively. The A value of the expression of the protein and mRNA of p21 in A549 cell strains were 0.17+/-0.03, 0.62+/-0.03 in the control group, 0.16+/-0.02, 0.50+/-0.02; 0.14+/-0.02, 0.36+/-0.02; 0.15+/-0.03, 0.49+/-0.03; 0.13+/-0.02, 0.33+/-0.02 in experimental groups A, B, D, E, respectively. These results indicate that the expression of HDAC1 is regulated by hypoxia and the effect of TSA is closely related to the expression of P21 under hypoxia condition.",
Arsenic,1359772,Fouling one's own nest Abstract: HEEP COPYRIGHT: BIOL ABS. CHILDREN HUMAN DERMATOLOGICAL REACTION NERVOUS SYSTEM INJURY LEAD ARSENIC TETRA CHLORO DI BENZODIOXIN OCCUPATIONAL EXPOSURE WORK CLOTHING DUST,
Arsenic,710822,"Arsenic in drinking water and adult mortality: A population-based cohort study in rural Bangladesh Abstract: Arsenic is a potent human carcinogen and toxicant. Elevated concentration of arsenic in drinking water is a major public-health problem worldwide. We evaluated risks of adult mortality (due to cancer and cardiovascular and infectious diseases) in relation to arsenic exposure through drinking water.<br /><br /> A cohort analysis was applied to survival data prospectively collected during 1991-2000 in a health and demographic surveillance system in Matlab, Bangladesh, where tubewells were installed beginning in the early 1970s. A total of 115,903 persons aged 15 or more years on 1 January 1991 were available for analysis. In this period, 9015 people died and 22,488 were lost to follow-up. Arsenic exposure data were derived from a survey in 2002-2003 of past and current water use and arsenic concentrations in all tubewells. We estimated risk of excess mortality in relation to arsenic exposure, using proportional hazards models.<br /><br /> Even at low levels (10-49 mug/L) of arsenic in drinking water, we observed increased risk of death due to all nonaccidental causes (hazard ratio = 1.16 [95% confidence interval = 1.06-1.26]). Increased risks at exposure of 50-149 microg/L were observed for death due to cancers (1.44 [1.06-1.95]), cardiovascular disease (1.16 [0.96-1.40]), and infectious diseases (1.30 [1.13-1.49]). We observed clear dose-response relationships for each of these causes.<br /><br /> Arsenic exposure through drinking water has generated excess adult mortality after 20-30 years of exposure.",
Arsenic,1508619,"Anaerobic Sulfur Metabolism Coupled to Dissimilatory Iron Reduction in the Extremophile Acidithiobacillus ferrooxidans Abstract: Gene transcription (microarrays) and protein levels (proteomics) were compared in cultures of the acidophilic chemolithotroph Acidithiobacillus ferrooxidans grown on elemental sulfur as electron donor under aerobic and anaerobic conditions, using either molecular oxygen or ferric iron as electron acceptor respectively. No evidence supporting the roles of either tetrathionate hydrolase or arsenic reductase in mediating the transfer of electrons to ferric iron was obtained (as suggested by previous studies). In addition, no novel &quot;ferric iron reductase&quot; was identified. However, data suggested that sulfur was disproportionated under anaerobic conditions, forming hydrogen sulfide via sulfur reductase, and sulfate via heterodisulfide reductase and ATP sulfurylase. Supporting physiological evidence for H(2)S production came from the observation that soluble Cu(2+) included in anaerobically-incubated cultures was precipitated (seemingly as CuS). Since H(2)S reduces ferric iron to ferrous in acidic media, its production under anaerobic conditions indicates that anaerobic iron reduction is mediated, at least in part, by an indirect mechanism. Evidence was obtained for an alternative model implicating the transfer of electrons from S(0) to Fe(3+) via a respiratory chain that includes a bc(1) complex and a cytochrome c. Central carbon pathways were up-regulated under aerobic conditions, correlating with faster growth rates, while many Calvin-Benson-Bassham cycle components were up-regulated during anaerobic growth, probably as a result of more limited access to carbon dioxide. These results are important for understanding the role of At. ferrooxidans in environmental biogeochemical metal cycling and in industrial bioleaching operations.",
Arsenic,1019956,"Direct determination of arsenic in steel by glow discharge optical emission spectrometry with argon-helium mixed gas Abstract: In glow discharge optical emission spectrometry, an argon-helium mixed gas plasma was investigated to improve the detection sensitivity of arsenic in steel samples. The emission line of arsenic was enhanced and the background intensity was simultaneously reduced when an Ar-He plasma was employed instead of an Ar plasma, which is effective for the sensitive determination of arsenic. The detection limits were calculated to be 0.009 mass% for a 700-V Ar plasma, 0.004 mass% for a 700-V Ar-He plasma, and 0.001 mass% for a 900-V Ar-He plasma.",
Arsenic,1508666,"Comprehensive monitoring of drinking well water quality in Seoul metropolitan city, Korea Abstract: In this research, the quality of drinking well waters from 14 districts around Seoul metropolitan city, Korea was assessed by measuring a number of parameters with established guideline (e.g., arsenic, fluoride, nitrate nitrogen, benzene, 1,2-dichloroethene, dichloromethane, copper, and lead) and without such criteria (e.g., hardness, chloride ion, sulfate ion, ammonia nitrogen, aluminum, iron, manganese, and zinc). Physical parameters such as evaporation residue (or total dissolved solids) and turbidity were also measured. The importance of each parameter in well waters was examined in terms of the magnitude and exceedance frequency of guideline values established by international (and national) health agencies. The results of this study indicate that among the eight parameters with well-established guidelines (e.g., WHO), arsenic and lead (guideline value of 0.01 mg?L(-1) for both) recorded the highest exceedance frequency of 18 and 16 well samples ranging in 0.06-136 and 2-9 mg?L(-1), respectively. As such, a number of water quality parameters measured from many well waters in this urban area were in critical levels which require immediate attention for treatment and continuous monitoring.",
Arsenic,628332,"Evaluation of DNA damage in patients with arsenic poisoning: Urinary 8-hydroxydeoxyguanine Abstract: The relationship between arsenic exposure and DNA damage in patients with acute or chronic arsenic poisoning was analyzed. Urinary 8-hydroxydeoxyguanine (8-OHdG) concentrations were measured as an indication of oxidative DNA damage. A remarkable increase in 8-OHdG in the urine was observed in 60% of 52 patients with acute arsenic poisoning from the accidental oral intake of the arsenic trioxide. This was two- to threefold higher than levels in normal healthy subjects (n = 248). There was a clear relationship between arsenic concentrations in urine after acute poisoning and elevated levels of 8-OHdG. Levels of urinary 8-OHdG returned to normal within 180 days after the acute arsenic poisoning event. In patients chronically poisoned by the consumption of well water with elevated levels of arsenate [As(V)], elevated 8-OHdG concentrations in urine were also observed. A significant correlation between the 8-OHdG levels and arsenic levels in the urine was observed in 82 patients with chronic poisoning. Thus, evidence of oxidative DNA damage occurred in acute arsenic poisoning by arsenite [As(III)] and in chronic arsenic poisoning by As(V). In chronic poisoning patients provided low-arsenic drinking water, evidence of DNA damage subsided between 9 months and 1 year after the high levels of arsenic intake were reduced. The initial level of arsenic exposure appeared to dictate the length of this recovery period. These data indicate that some aspects of chronic and acute arsenic poisoning may be reversible with the cessation of exposure. This knowledge may contribute to our understanding of the risk elevation from arsenic carcinogenesis and perhaps be used in a prospective fashion to assess individual risk.",
Arsenic,2064270,"Crystalline and glassy phases in the Cs/Bi/As/S system Abstract: The quaternary Cs2S/Bi/As/S system was studied in an attempt to introduce two different asymmetric but isoelectronic building units, namely, [Bi(III)xSy] and [As(III)xSy], in a single structure. Reactions with a comparatively lower equivalent of arsenic in the Cs2S/Bi/As/S mixture led to the crystalline compound Cs3Bi(AsS4)2. The structure features tetrahedral [As(V)S4](3-) connected to Bi(III) centers to give infinite (1)/?[Bi(AsS4)2(3-)] chains. When the basicity was raised in these low arsenic fluxes by increasing the Cs2S fraction, the crystalline compound Cs9Bi(AsS4)4, also featuring [As(V)S4](3-) anions, was formed. On the other hand, arsenic-rich mixtures of Cs2S/Bi/As/S led to the formation of the glassy phase Cs2BiAs3S7, which contains As(III) species. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and pair distribution function (PDF) analysis indicate the presence of As(III)-containing [AsnS2n+1] fragments in the glass structure. Several glasses in the series Csn-1BiAsnS2n+1 were also prepared using solid-state fusion reactions. The band gaps of the Csn-1BiAsnS2n+1 glasses are in the range of 1.51-1.81 eV, while that of the crystalline compound Cs3Bi(AsS4)2 is ?2.33 eV. The thermal and optical behaviors of these compounds are correlated with their structures and building units.",
Arsenic,196993,"Occupational exposure to phenoxy herbicides and chlorophenols and cancer mortality in the Netherlands Abstract: As part of the ""IARC International Register of Persons Exposed to Phenoxy Herbicides and Contaminants,"" a cohort of workers who manufacture and prepare chlorophenoxy herbicides was recruited in The Netherlands. The cohort comprised 2,310 workers from two plants, operated by different companies, who were followed during the periods 1955-1985 and 1965-1986, respectively. In 1963, there had been an industrial accident in one factory with concomitant release of dioxin into the environment. Loss to follow-up was 3%. Mortality data on 963 exposed and 1,111 nonexposed men were evaluated by external and internal comparison. Compared with national rates, total mortality (94 deaths, standardized mortality ratio [SMR] = 101; 95% confidence interval [CI], 82-124) and cancer mortality (31 deaths, SMR = 107; 95% CI, 73-152) for exposed workers were not significantly increased. A statistically insignificant increase was observed for non-Hodgkin's lymphoma (2 deaths, SMR = 299; 95% CI, 36-1,078). No cases of soft-tissue sarcoma were encountered. There was no increase in either total mortality (25 deaths, SMR = 111; 95% CI, 72-163) or cancer mortality (10 deaths, SMR = 137; 95% CI, 66-252) among the 139 workers probably exposed to dioxins during the 2,4,5-trichlorophenol production accident or the subsequent clean-up operations. Compared with nonexposed workers, exposed workers did not exhibit a higher total mortality (rate ratio [RR] = 1.28; 95% CI, 0.89-1.82). Mortality due to all cancers (RR = 1.7; 95% CI, 0.9-3.4) and respiratory cancer (RR = 1.7; 95% CI, 0.5-6.3) was insignificantly elevated. These findings suggest that the increases in cancer mortality among workers exposed to phenoxy herbicides and chlorophenols may be attributable to chance. Lack of power prevented evaluation with respect to specific cancers.",
Arsenic,735161,"Evaluation of DNA Damage in People Occupationally Exposed to Arsenic and Some Heavy Metals Abstract: Arsenic (As) is a human carcinogen with a high risk of cancer development in people exposed to it in industry and in the general environment. The mechanisms involved in arsenic carcinogenesis are still unknown, There is a hypothesis that reactive oxygen species (ROS) may play an important role in arsenic carcinogenesis. 8-hydroxydeoxyguanosine is a nucleotide form that results from oxidative DNA damage, which causes mutation in vitro and in vivo. So the occurrence of 8-OHdG (8-hydroxy-2'-deoxyguanosine) has been used to study damaging effects on DNA of ROS.",
Arsenic,1340444,"Cysteinyl-tRNA deacylation can be uncoupled from protein synthesis Abstract: Aminoacyl-tRNA synthetases (ARSs) are critical components of protein translation, providing ribosomes with aminoacyl-tRNAs. In return, ribosomes release uncharged tRNAs as ARS substrates. Here, we show that tRNA deacylation can be uncoupled from protein synthesis in an amino acid specific manner. While tRNAs coupled to radiolabeled Met, Leu Lys, or Ser are stable in cells following translation inhibition with arsenite, radiolabeled Cys is released from tRNA at a high rate. We discuss possible translation independent functions for tRNA(Cys).",
Arsenic,1677627,"Synthesis of au-decorated tripod-shaped te hybrids for applications in the ultrasensitive detection of arsenic Abstract: Novel Au-decorated Te hybrids with a tripod-shaped planar microstructure were prepared through a two-step hydrothermal process: the synthesis of Te single crystals and the subsequent self-sacrificial reaction of Te template with HAuCl4. Based on the influences of reaction temperature and solvent compositions on the as-obtained microstructures, a plausible mechanism was proposed to account for the formation of the tripod-shaped Te and Au/Te crystals. The as-prepared Au/Te hybrids have the sensitivity of 6.35 ?A/ppb in the electrochemical detection of As(III), which represents the highest sensitivity reported in literature. The Au/Te sensor also has a low detection limit of 0.0026 ppb and could work in complex mixtures containing As(III), Cu(II) and other heavy metal ions, exhibiting excellent selectivity on As(III) and Cu(II) ions. The enhanced electrocatalytic property may be attributed to the synergetic interactions between the noble metal and semiconductor and the presence of a large number of active sites on the hybrids surface.",
Arsenic,2278844,"The isotypic hydrogen phosphate and arsenate dihydrates M2HXO4·2H2O (M = Rb, Cs; X = P, As) Abstract: The four isotypic alkaline metal monohydrogen arsenate(V) and phosphate(V) dihydrates M2HXO4·2H2O (M = Rb, Cs; X = P, As) [namely dicaesium monohydrogen arsenate(V) dihydrate, Cs2HAsO4·2H2O, dicaesium monohydrogen phosphate(V) dihydrate, Cs2HPO4·2H2O, dirubidium monohydrogen arsenate(V) dihydrate, Rb2HAsO4·2H2O, and dirubidium monohydrogen phosphate(V) dihydrate, Rb2HPO4·2H2O] were synthesized by reaction of an aqueous H3XO4 solution with one equivalent of aqueous M2CO3. Their crystal structures are made up of undulating chains extending along [001] of tetrahedral [XO3(OH)](-) anions connected via strong O-H...O hydrogen bonds. These chains are in turn connected into a three-dimensional network via medium-strength hydrogen bonding involving the water molecules. Two crystallographically different M(+) cations are located in channels running along [001] or in the free space of the [XO3(OH)](-) chains, respectively. They are coordinated by eight and twelve O atoms forming irregular polyhedra. The structures possess pseudosymmetry. Due to the ordering of the protons in the [XO3(OH)](-) chains in the actual structures, the symmetry is reduced from C2/c to P21/c. Nevertheless, the deviation from C2/c symmetry is minute.",
Arsenic,1339201,"Mouse micronucleus assay as a surrogate to assess genotoxic potential of arsenic at its human reference dose Abstract: Exposure to high contents of arsenic (a genotoxic carcinogen) in humans through drinking water is one of the most serious concerns in many parts of the world including India. The United States Environmental Protection Agency (USEPA) has recommended a permissible limit of daily exposure in humans to arsenic as its reference dose (0.3?gkg(-1)d(-1)) with almost no likelihood of any adverse effect. The present work was a quantitative assessment of the genotoxic potential of arsenic at the exposure level of its human reference dose through micronucleus (MN) assay in mice. The animals were exposed to various doses of arsenic through oral gavaging for 15 consecutive days. Significant increases in the frequency of micronucleated erythrocytes were observed in mice upon exposure to arsenic which occurred even at its human reference dose and in a dose-dependent manner. The study of the genotoxic potential of arsenic in humans at lower exposure levels (including its human reference dose) is, therefore, highly desirable for risk assessment and hazard identification.",1
Arsenic,466704,"Arsenic, Cadmium and Lead in Beers from the Italian Market Abstract: Nineteen beer brands from the Italian market were surveyed for the presence of arsenic, cadmium and lead in January of 2007. Detection was performed by means of inductively coupled plasma-mass spectrometry (ICP-MS). Average arsenic content was 10.82 +/- 5.54 mu g/L, while cadmium (0.16 +/- 0.15 mu g/L) and lead (1.84 +/- 3.24 mu g/L) were significantly lower (P<0.05). Overall, this survey indicated that beer may contribute heavy metals to the diet. Nevertheless, the dietary exposure to these contaminants is unlikely to constitute a hazard to the consumer's health due to the low level of contamination found and to the low annual per capita consumption of beer in Italy.",
Arsenic,627239,"Modulation of cellular antioxidant defense activities by sodium arsenite in human fibroblasts Abstract: Many studies have shown that oxygen radicals can be produced during arsenic metabolism. We report here that in human fibroblasts (HFW cells) sodium arsenite exposure caused increased formation of fluorescent dichlorofluorescein (DCF) by oxidation of the nonfluorescent form. The enhanced DCF fluorescence was inhibited by a radical scavenger, butylated hydroxytoluene. The effects of sodium arsenite treatment on cellular antioxidant activities were then examined. Treatment of HFW cells with sodium arsenite resulted in a significant increase in heme oxygenase activity and ferritin level. Sodium arsenite-enhanced heme oxygenase synthesis was inhibited by co-treatment of cells with the antioxidants sodium azide and dimethyl sulfoxide. Furthermore, sodium arsenite treatment did not apparently affect glucose-6-phosphate dehydrogenase activity, but resulted in significantly increased glutathione levels and superoxide dismutase activity, slightly decreased glutathione peroxidase activity, and significantly decreased catalase activity. Sodium arsenite toxicity was partly reduced by addition of catalase to the culture medium. These results imply that arsenite can enhance oxidative stress in HFW cells.",
Arsenic,1327081,"Melatonin attenuates arsenite-induced apoptosis in rat brain: involvement of mitochondrial and endoplasmic reticulum pathways and aggregation of alpha-synuclein Abstract: In the present study, the protective effect of melatonin on sodium arsenite (arsenite)-induced apoptosis was investigated. Local infusion of arsenite elevated lipid peroxidation and depleted glutathione content in the infused substantia nigra (SN), as well as reduced striatal dopamine content. Systemic administration of melatonin diminished arsenite-induced oxidative injury. Furthermore, melatonin attenuated arsenite-induced increases in heat shock protein 70 and heme oxygenase-1 as well as phosphorylation of p38 mitogen-activated protein kinase and elevations in cyclooxygenase II and inducible nitric oxide synthase expression. Inhibition by melatonin of arsenite-induced apoptosis was determined by its attenuation of DNA fragmentation and terminal deoxytransferase-mediated dUTP-nick end labeling's positive cells in the infused SN of melatonin-treated rats. Melatonin reduced arsenite-induced apoptosis through mitochondrial and endoplasmic reticulum (ER) pathways. In the mitochondrial pathway, systemic melatonin inhibited arsenite-induced elevations in Bcl-2 and cytosolic cytochrome c as well as arsenite-induced reductions in procaspase-3 levels and elevations in active caspase-3 levels in the infused SN. Regarding the ER pathway, melatonin attenuated arsenite-induced elevations in activating transcription factor-4, CCAAT/enhancer binding protein (C/EBP) homologues protein, X-bon binding protein (XBP-1) and cytosolic immunoglobulin binding protein (BIP) as well as reductions in procaspase 12 levels. Moreover, aggregation of alpha-synuclein was reduced in the arsenite-infused SN of melatonin-treated rats. Our in vitro data showed that melatonin ameliorated arsenite-induced lipid peroxidation. Taken together, our data suggest that melatonin is neuroprotective against arsenite-induced oxidative injury in the nigrostriatal dopaminergic system of rat brain. Furthermore, the neuroprotective effects by melatonin on arsenite-induced apoptosis were mediated via inhibiting both mitochondrial and ER pathways. Accordingly, melatonin may be therapeutically useful for the treatment of arsenite-induced apoptosis in central nervous system.",
Arsenic,1250968,"GFAJ-1 Is an Arsenate-Resistant, Phosphate-Dependent Organism Abstract: The bacterial isolate GFAJ-1 has recently been proposed to substitute arsenic for phosphorus to sustain growth. We have shown that GFAJ-1 is able to grow at low phosphate concentrations (1.7 ?M), even in the presence of high concentrations of arsenate (40 mM), but lacked the ability to grow in phosphorus-depleted (&lt;0.3 ?M), arsenate-containing medium. High-resolution mass spectrometry analyses revealed that phosphorylated central metabolites and phosphorylated nucleic acids predominated. A few arsenylated compounds, including C6 sugar arsenates, were detected in extracts of GFAJ-1, when GFAJ-1 was incubated with AsO(4)(3-), but further experiments showed that they formed abiotically. Inductively coupled plasma mass spectrometry confirmed the presence of phosphorus and the absence of arsenic in nucleic acid extracts. Taken together, we conclude that GFAJ-1 is an arsenate-resistant, but still a phosphate-dependent bacterium.",
Arsenic,134643,"Strain-dependent disposition of inorganic arsenic in the mouse Abstract: Recent studies have suggested that polymorphisms in the methylation of inorganic arsenic (iAs) exist in animals and humans. Methylation of iAs is an important step in the elimination of arsenic. The objective of this study was to examine whether there are differences in iAs disposition, and hence methylation, between three strains of mice. Ninety-day-old female mice (strains: C3H/HeNCrlBR, C57BL/6NCrlBR, and B6C3F1/CrlBR) were administered [73As]arsenate or [73As]arsenite orally at dose levels of 0.5 or 5.0 mg As/kg. Another group of mice were administered [73As]arsenate (5.0 mg As/kg) intraperitoneally (i.p.). Disposition of [73As] was assessed by whole-body counting, and analysis of urine, feces and tissues for radioactivity. Urine was analyzed by chromatography for arsenic metabolites. Several strain- and dose-related effects in the disposition of [73As] were observed with both arsenicals. After oral administration, the clearance of [73As]arsenate, measured by whole-body counting, was dependent on the strain. However, because there was no strain dependence on clearance of [73As]arsenate administered i.p., the effect after oral administration may be due to a difference in absorption of arsenate between the strains. With increased oral dose of arsenate and arsenite, the clearance of [73As] was slower and there was higher tissue retention of [73As]. The percentage of metabolites excreted in urine also was affected by the administered dose. With increased dose, the percentage of arsenite and monomethylarsonic acid were significantly increased, and dimethylarsinic acid decreased. However, our results suggest there is no overall difference between these strains of mice with respect to disposition of iAs. A better understanding of the role of phenotype in the disposition and toxicity of iAs would reduce the uncertainty in arsenic risk assessment.",
Arsenic,1520113,"Effect of arsenic and arsenic metabolites on LTCC and BKCa expression and activities in vascular smooth muscle Abstract: Background: Arsenic (As) contamination of ground- and well-water is common worldwide. Chronic As exposure can produce toxic effects including atherosclerosis and hypertension, yet mechanisms by which both inorganic As and As metabolites induce these effects are not well elucidated. Both arsenite (iAs3+) and its metabolite monomethylarsonous acid (MMAs3+) are believed to affect the activity of critical Vascular Smooth Muscle (VSM) components including the ‘L-type’ calcium channel (LTCC), a key regulator of VSM tone, as well as the large-conductance calcium-activated potassium channel (BKCa), a known modulator of cell depolarization implicated in the development of hypertension and restenosis disease. Objectives and Methods: This study examines effects of iAs3+ and MMAs3+ on expression and related activities of LTCC and BKCa in acutely isolated and primary / tissue cultured rat thoracic aorta, as well as the A7r5 rat thoracic aorta VSM cell line, using whole-cell patch clamp, vascular contractility, RT-QPCR, and light microscopy. Results: Initial results indicate alterations in VSM cell morphology, viability, LTCC activity, and responsiveness to PE-induced vasoconstriction on acute and subchronic exposure to both iAs3+ and MMA3+. Conclusions: Both iAs3+ and MMA3+ affect activities of key effectors governing the maintenance of VSM tone.",
Arsenic,2149349,"The influence of dissolved natural organic matter on the stability of Arsenic species in groundwater Abstract: Arsenic bioavailability, toxicity and mobility depend on its speciation. In aquatic environments arsenic is mainly found in two oxidation states and three oxianion forms, i.e., H3AsO3, H2AsO4 - and HAsO4 2-. The stability of As(III) and As(V) has been reported to be dependent on water pH, redox potential, microbial activity, concentration of iron, manganese and natural organic matter (NOM). NOM is ubiquitous in aquatic and terrestrial systems. NOM particles, such as fulvic acid (FA) and humic acid (HA) particles, bind very strongly to (hydr)oxide minerals limiting arsenic adsorption on mineral surface. In addition to the competition effects for adsorption, NOM may influence arsenic distribution via some other mechanisms. For instance, degradation and oxidation of NOM may be coupled with reduction of arsenate to arsenite. More recently, few studies have also postulated that arsenic can form organic complexes with the dissolved fraction of natural organic matter (DOM). In spite of this recent evidence, quantitative data on As-DOM interaction are still missing. Aim of this study was to investigate the effect of DOM on temporal stability of inorganic arsenic species in aqueous matrices taking into account the influence of pH, redox potential, ionic strength, Fe and Mn concentrations. Batch experiments were performed using arsenate and arsenite-containing solutions spiked with variable quantities of DOM extracted from aliquots of lake water. During the contact time, all the reaction systems were incubated at a preset temperature in the range 8-25°C. At first As(III) and As(V) stability was studied in synthetic water solutions containing inorganic salts, then the same experiments were repeated using real samples collected from an Italian volcanic aquifer. Speciation analyses to evaluate the ratio between the two inorganic species were carried out with solid phase extraction followed by electrothermal atomic absorption spectrometry. The complexation of arsenic with DOM was examined with gel filtration chromatography.",
Arsenic,1337291,"Children exposure to trace levels of heavy metals at the north zone of Kifissos River Abstract: This study evaluates the exposure level of primary school children at three different towns in northern Attica, near the banks of the Kifissos River, defining referential values of toxic heavy metals. Concentrations of five toxic metals (arsenic, cadmium, mercury, lead and nickel) were analyzed in water samples from the Kifissos River as well as in the scalp hair of children aged 11 to 12years old living in the study area. Chronic low-level toxicity of lead and cadmium came into view in recent years as a problem of our civilization. Exposure to concentrations of arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) poses a potential threat to humans and can cause effects on children's renal and dopaminergic systems without clear evidence of a threshold, a fact that reinforces the need to control all the potential heavy metal emissions into the environment in order to protect children's health. The results were analyzed with the IBM SPSS Statistics 20 for Windows. The possible influence of sex and area was examined. Statistical differences were observed by t-test between the log-transformed hair concentrations of lead (p=0.021), arsenic (p=0.016) and nickel (p=0.038) in children's scalp hair from the municipalities of Kifisia and Kryoneri. ANOVA one-way test confirmed the difference of Pb concentration in hair between girls and boys from the municipality of Kifisia (p=0.038). The t-test confirms the difference of heavy metal concentrations in river samples between the municipalities Kifisia and Philadelphia in comparison with the samples from Kryoneri. The observations suggest that children living at the municipality of Kifisia are exposed to higher concentrations of heavy metals than the others. Despite all the confounding factors, hair can be used as a biomarker in order to determine the exposure to heavy metals, according to standardized protocols.",
Arsenic,2278352,"Lubiprostone for the treatment of functional constipation in children Abstract: <strong>OBJECTIVES: </strong>Pediatric functional constipation is common; effective, easily administered treatment options are limited. Lubiprostone is an oral chloride channel protein-2 activator that stimulates gastrointestinal fluid secretion, softens stools, and facilitates bowel movements (BMs). We evaluated the safety and effectiveness of lubiprostone in children and adolescents with functional constipation.<br /><br /><strong>METHODS: </strong>Patients ?12 kg, 17 years or younger, and with &lt;3 spontaneous BMs (SBMs; ie, BMs that did not occur within 24 hours of rescue medication use) per week were enrolled at 22 US general pediatric and pediatric gastroenterology centers (January 2007-October 2008). Patients received 4 weeks of open-label lubiprostone at doses of 12 ?g once daily (QD), 12 ?g twice daily (BID), or 24 ?g BID based on age and weight. The primary endpoint was SBM frequency during week 1 versus baseline.<br /><br /><strong>RESULTS: </strong>Of 127 enrolled patients, 124 were treated and analyzed (12 ?g QD, n?=?27; 12 ?g BID, n?=?65; 24 ?g BID, n?=?32), and 109 completed the study. The mean age of treated patients was 10.2 years (range 3-17 years); 65 were boys. Mean SBM frequency significantly increased compared with baseline at week 1 (3.1 vs 1.5 SBMs/week, P?&lt;?0.0001). SBM frequency was improved significantly from baseline overall (P?&lt;?0.0001) and for individual dose groups (P???0.0062) during weeks 2, 3, and 4. Common (?5%) adverse events included nausea (18.5%), vomiting (12.1%), diarrhea (8.1%), abdominal pain (7.3%), and headache (5.6%). Two patients experienced serious adverse events (unrelated abdominal pain; unrelated sickle cell crisis).<br /><br /><strong>CONCLUSIONS: </strong>Lubiprostone was efficacious and well tolerated in children and adolescents with functional constipation.",
Arsenic,1332366,"Regulation of expression of the human heme oxygenase-1 gene in transfected chick embryo liver cell cultures Abstract: Induction of heme oxygenase (HO) has been proposed as a protective cellular mechanism against oxidative damage. In previous work (Tyrrell et al., Carcinogenesis [1993] 14, 761-765), portions of the 5' promoter region of the human HO-1 gene linked to the reporter gene chloramphenicol acetyl transferase (CAT), had been transiently expressed in HeLa cells. To extend the study of human HO gene expression into primary liver cells, these reporter gene fusion constructs, containing 121 or 1416 base pairs of the untranscribed 5'-upstream sequences of the human HO-1 gene, were used along with pSV beta-Gal plasmid to dually transfect primary cultures of chick embryo liver cells (CELC). The transfected cells were treated with selected metals, heme, phorbol ester, and chemical agents that produce oxidative stress (H2O2 or sodium arsenite). Reporter gene activities were measured 18-20 h later. Our major findings are: (1) these HO-CAT constructs were expressed in CELC; (2) unlike HeLa cells, the expression of CAT was detected in CELC without the need for the SV40 enhancer; (3) sodium arsenite and cobalt chloride induced the expression of the HO-CAT constructs whereas heme had no effect on or decreased CAT expression for all of the transfected constructs; (4) study of endogenous chick HO-1 gene expression in CELC showed that HO-1 responded to sodium arsenite treatment in a dose-dependent fashion, and the response was rapid and transient. We conclude that, in chick liver cell cultures, induction of the HO-1 gene by heme is fundamentally different from that produced by transition metals or sodium arsenite. Furthermore, the results suggest that expression of the HO-1 gene is highly conserved across species.",
Arsenic,2149160,"Effects of sediment containing coal ash from the Kingston ash release on embryo-larval development in the fathead minnow, Pimephales promelas (Rafinesque, 1820) Abstract: The largest environmental release of coal ash in US history occurred in December 2008 with the failure of a retention structure at the Tennessee Valley Authority Kingston Fossil Fuel Plant in East Tennessee. A byproduct of coal-burning power plants, coal ash is enriched in metals and metalloids such as selenium and arsenic with known toxicity to fish embryonic and larval life stages. The early development of fish embryos and larvae during contact exposures to river bottom sediments containing up to 78 % coal ash from the Kingston spill was examined in 7-day laboratory tests with the fathead minnow (Pimephales promelas). No significant effects were observed in hatching success, incidences of developmental abnormalities, or embryo-larval survival. Results suggest that direct exposures to sediment containing residual coal ash from the Kingston ash release may not present a significant risk to fish eggs and larvae in waterways affected by the coal ash spill.",
Arsenic,2088329,"Assessment of arsenic toxicity in rice plants in areas of West Bengal Abstract: Pot culture experiments were conducted using graded doses of arsenic (As) in order to determine the toxicity symptoms in rice plants. The As accumulation by the plant parts generally followed the order: root>stem>leaf>economic produce. Yield reduction of 80.8% was observed in treatment applying more than 60 mg kg-1 As. The arsenic toxicity symptoms in leaf and root were observed with treatment above 40 mg kg-1 As, while the symptoms were apparent in economic produce above 60 mg kg-1. The phytotoxicity threshold levels were observed with yield reduction to 55.5% in tillering and 54.8% at harvesting. In field experiments of rice-green manure–rice cropping sequence, no toxicity symptoms developed but a greater extent of As accumulation in rice crops was observed. The application of green manure does not significantly reduce As accumulation in the plants. The As accumulation and translocation factors in both experiments revealed the following order of root>stem>leaf>economic produce.",
Arsenic,2345653,"Chromatographic separation of arsenic species with pentafluorophenyl column and application to rice Abstract: Arsenic species, including arsenous acid, arsenic acid, methylarsonic acid, and dimethylarsinic acid, were determined using HPLC-ICPMS. The species were separated with a Discovery HS F5 column and a simple, volatile, and isocratic mobile phase of 0.1% (v/v) formic acid and 1% (v/v) methanol. The Discovery HS F5 column with a pentafluorophenyl (PFP) stationary phase gave sharp peaks and full separation of the arsenic species in 5min, and other PFP columns showed lower performance. This separation method was applied to arsenic species analysis in rice. The extraction of arsenic from rice samples was performed using 0.15M nitric acid. The methodology was validated by use of certified reference materials, NMIJ CRM 7503-a and NIST SRM 1568a, and extremely low arsenic rice samples as blank samples.",
Arsenic,1378597,"EFFECTS OF INORGANIC ARSENIC ON LYMPHOCYTE STIMULATION AND PROLIFERATION Abstract: IN A STUDY OF EARLY BIOLOGICAL MARKERS ON A HYDROARSENICISM EXPOSED GROUP, WE FOUND A SIGNIFICANT EFFECT IN THE CELL CYCLE KINETICS AND A LONGER AVERAGE GENERATION TIME. KNOWING THAT THIS IS A VARIABLE PARAMETER THAT COULD APPEAR IN A GROUP OF INDIVIDUALS DUE TO INFECTIONS AND OTHER FACTORS, WE STUDIED THE EFFECTS OF INORGANIC ARSENIC ON LYMPHOCYTE STIMULATION AND PROLIFERATION. 72 H HUMAN LYMPHOCYTE CULTURES WERE TREATED WITH ARSENITE AND ARSENATE (10(-7), 10(-8) AND 10(-9) M) DURING THE LAST 24 H AND OTHERS AT THE BEGINNING OF THE CULTURES WITH OR WITHOUT PHA (G1, GN LYMPHOCYTES RESPECTIVELY). THE R.I. DIMINISHED IN A DOSE RELATED MANNER WHEN LYMPHOCYTES WERE TREATED DURING THE LAST 24 H AND ALSO WHEN EXPOSED TO 10(-9) M OF AS AT THE BEGINNING OF THE CULTURES WITH OR WITHOUT PHA (P 0.05). THE INHIBITION OF PROLIFERATION WAS GREATER WHEN CELLS WERE TREATED IN THE ABSENCE OF PHA (P 0.05), WHILE THE CELL VIABILITY WAS NOT AFFECTED. MOST LYMPHOCYTES IN VIVO USUALLY ARE G0, PHASE WHICH IN OUR STUDIES IN VITRO WAS THE MOST SENSITIVE SINCE PROLIFERATION WAS COMPLETELY INHIBITED. WE THINK THAT THE CONTRADICTORY DATA ON IN VIVO AND IN VITRO GENOTOXIC EFFECTS COULD BE DUE TO THE FACT THAT CELLS WHICH HAD GOT THE HIGHEST CONTENT OF AS WILL NOT EVEN DIVIDE. THE LAG IN LYMPHOCYTE PROLIFERATION COULD MEAN AN IMPAIRMENT OF THE IMMUNE RESPONSE DUE TO ARSENIC.",
Arsenic,628122,"P53 alterations in bladder tumors from arsenic and tobacco exposed patients Abstract: Previous studies demonstrated that tobacco and arsenic exposure are risk factors for bladder cancer. A case-case study was conducted to compare p53 mutations in 147 bladder tumors from South American patients by tobacco and arsenic exposure. Information on residential history and lifestyle factors was collected. The prevalence of p53 mutations and protein expression was examined in relation to tumor stage, grade, patient age, gender, tobacco and arsenic exposure. Smokers were grouped as ever/never smokers and by pack years of exposure (0, 1-20, >20). Patients were also grouped into four arsenic exposure categories based on the average of the five highest years arsenic concentration in their drinking water: group 1, non-detectable to <10 microg/l (n = 50); group 2, 10-99 microg/l (n = 31); group 3, 100-299 microg/l (n = 35); group 4, >300 microg/l (n = 30). The proportion of tumor samples with p53 mutations and P53 immunopositivity increased strongly with both stage and grade, but not with arsenic exposure or smoking. The prevalence of tumors containing mutational transitions increased markedly with tumor stage (from 14 to 52%, P(trend) = 0.005) and grade (from 11 to 48%, P(trend) = 0.004) and was higher in smokers than in non-smokers (34 versus 18%, respectively, P = 0.10). An increasing trend was observed with pack years of smoking (P = 0.09). The majority of mutations in tumors from both smokers and non-smokers were G-->A transitions, however, in smokers a preference for G-->A transitions at CpG sites was observed (P = 0.07, two-tailed) and a positive trend was observed with pack years of exposure (P = 0.04). A hotspot was found at codon 273 in 12% of the tumors from smokers but was not observed in never smokers (P = 0.05) and a positive trend was observed with pack years of tobacco exposure (P = 0.001). Neither stage nor grade demonstrated a preference for CpG site mutation, suggesting that these changes may be early exposure-related events in carcinogenesis and are not related to tumor progression. Arsenic exposure was not associated with an increased prevalence of p53 mutation or P53 immunopositivity and there was no evidence of interaction between arsenic and smoking with these outcome variables.",
Arsenic,1340131,"Increased neuron specific enolase expression by urothelial cells exposed to or malignantly transformed by exposure to Cd²? or As³? Abstract: Neuron specific enolase (ENO2, ?-enolase) is a biomarker used to help identify neuroendocrine differentiation in tumors. This laboratory has shown that ENO2 might be a biomarker for exposure to cadmium and arsenite. In this study these observations are extended to the urothelial cell, where environmental exposures are strongly linked to urothelial cancer. The UROtsa urothelial cell line and its Cd²?- and As³?-transformed counterparts were used as the model. Acute exposure of the UROtsa cells to both As³?- and Cd²?-caused significant increases in ENO2 expression. Treatment with the histone deacetlyase inhibitor was also shown to significantly increase the expression of ENO2 mRNA. The expression of ENO2 was significantly elevated in the Cd²?- and As³?-transformed UROtsa cells and tumor transplants. In contrast, ENO1, was unaffected by exposure to As³? or Cd²?. Immunofluorescence showed ENO2 associated with both the nucleus and cytoplasm and cytoplasmic ENO2 co-localized with ENO1. The findings extend the evidence suggesting a link between As³? and Cd²? exposure and neuroendocrine differentiation in tumors. The results suggest that ENO2 might be a biomarker of human exposure to Cd²? and As³? that operates through histone modification.",
Arsenic,1024321,"Environmental arsenic exposure of schoolchildren in a former tin mining and smelting community of southern Thailand Abstract: Risk behavior and environmental sources of exposure to arsenic for 10-year-old schoolchildren were studied in a high exposure area and a low exposure area of Ron Phibun Subdistrict, Ron Phibun District, Nakhon Si Thammarat Province and compared to those in a control area. Arsenic concentrations of surface soil, ambient air and drinking water to which subjects in the high exposure group, the low exposure group and the control group were exposed, were significantly different (p &lt; 0.05). Similarly, urinary concentrations of total arsenic and the sum of inorganic arsenic and its metabolites were significantly higher in the study groups than the control group. The arsenic content of locally grown agricultural produce was small with the exception of freshwater snails (Sinotaia ingallsiana). Drinking water and surface soil were found to be the main sources of exposure. The exposure was mediated by the subjects' risk behavior, such as playing with soil and no hand-washing before eating. The estimated cancer risk from arsenic for the schoolchildren in the study area was between 10(-5)-10(-6) which meant that their risk of developing cancer was probable. Measures to reduce the cancer risk are recommended.",
Arsenic,628137,"Lung cancer and exposure to arsenic in rural Bangladesh Abstract: BACKGROUND: Arsenic is a known carcinogen but the risk of lung cancer from the widespread contamination of drinking water in rural Bangladesh has not been estimated. OBJECTIVES: To determine whether estimated exposure of villagers in Bangladesh to arsenic in drinking water differed between those with lung cancer and those with non-malignant lesions. METHODS: Data were obtained from 7286 subjects who underwent lung biopsy in 2003-2006 at a diagnostic centre taking referrals from throughout Bangladesh. Analysis was limited to 5372 people living in villages for the last 10 years who reported using tube well water. Of these, 3223 with a primary lung tumour were enrolled as cases and 1588 with non-malignant lesions as referents in an unmatched analysis. Arsenic exposure was estimated by average concentrations for each of 64 districts. Logistic regression was used to test the effects of age, arsenic and smoking on risk and to investigate relationship to cell type. RESULTS: Male cases were older than referents and more likely to smoke, to smoke >20 units/day and to smoke bidi-small, hand-rolled cigarettes. Odds ratios for lung cancer increased steadily with mean arsenic concentration, but the confidence interval excluded 1.0 only at concentrations >100 mug/l (OR 1.45, 95% CI 1.16 to 1.80). This trend was seen only in smokers where the increased risk at >100 mug/l was 1.65 (95% CI 1.25 to 2.18). A similar trend was seen in women smokers. Squamous cell lung cancer was more frequent in smokers and, having adjusted for smoking, in districts with arsenic concentrations >100 mug/l. CONCLUSIONS: Among Bangladeshis who smoke, those whose drinking water is contaminated with arsenic at concentrations >100 mug/l are at increased risk of lung cancer. With high levels of exposure misclassification and short latency of exposure, the study cannot estimate or exclude the likely long term risk in non-smokers and at lower arsenic concentrations.",
Arsenic,1453817,"Protective Effect of Psidium guajava in Arsenic-induced Oxidative Stress and Cytological Damage in Rats Abstract: This study was undertaken to evaluate the protective effect of aqueous extract of Psidium guajava leaves against sodium arsenite-induced toxicity in experimental rats. Animals were divided into four groups. Control group received arsenic free distilled water and three treatment groups (II, III, and IV) exposed to the arsenic (NaAsO(2)) (20 mg/kg b.wt) through drinking water. Group III and IV were administered a daily oral dose of P. guajava leaf extract 50 and 100 mg/kg b.wt. (AEPG(50) and AEPG(100)) for the period of 6 weeks. Blood samples and organs were collected at the end of the experiment. Arsenic exposure resulted in significant rise in lipid peroxidation (LPO) levels in erythrocyte, liver, kidney, and brain. In addition toxin decreased (P&lt;0.05) the level of reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activities in the studied tissues. Residual effect of arsenic in various tissues was also observed. Histopathological results revealed mild to severe type of necrosis and degenerative changes in kidney and liver of arsenic intoxicated animals. Cytological alteration in brain tissue was also observed. Treatment with AEPG(100) (aqueous extract of P. guajava) @100 mg/kg body weight) significantly restored activities of oxidative stress markers like LPO levels, GSH levels, SOD, and CAT activities but having the limited protective activity of the herbal extract was observed on tissues architecture. It is therefore concluded that prophylactic co-administration of AEPG could provide specific protection from oxidative injury and to some extent on tissue damage.",
Arsenic,2345610,"Assessment of arsenic-induced DNA damage in goldfish by a polymerase chain reaction-based technique using random amplified polymorphic DNA markers Abstract: Arsenic is a groundwater contaminant of global concern. It is a potent human carcinogen, and its marked genotoxic effects have been reported in several human and animal studies. The present work investigates the applicability of the random amplified polymorphic DNA (RAPD) assay to study the DNA-damaging effects of arsenic at low-level exposure in goldfish Carassius auratus. Four experimental groups of fish, A, B, C and D, were exposed to 0, 10, 50, and 1,000 µg L(-1) of arsenic, respectively, in aquaria water for 15 consecutive days. Genomic DNA extraction was followed by RAPD-polymerase chain reaction amplification for each fish separately. One arbitrary decamer primer (PUZ-19) of 33 primers used appeared as the most informative and was capable of exhibiting marked alterations in RAPD profiles between arsenic-exposed and unexposed (control) samples. Different sets of 11 loci were amplified in various experimental groups with four clear polymorphic bands by the primer PUZ-19. The X and XIII amplification loci, which were prominent in the unexposed group, failed to appear in the arsenic-exposed groups. In contrast, the I and XI RAPD bands appeared as new amplification loci in all of the exposed groups. Such alterations in genomic DNA, however, did not exhibit a clear dose-dependent tendency. The RAPD assay, because of its efficacy to unmask alterations in genomic DNA induced by arsenic at low exposure level of 10 µg L(-1), appears to be a sensitive and potential tool for detecting arsenic genotoxicity.",
Arsenic,1248941,"Dietary Yucca schidigera supplementation reduces arsenic-induced oxidative stress in Swiss albino mice Abstract: The aim of this study was to clarify the effects of dietary supplementation with Yucca schidigera (Ys) on lipid peroxidation (LPO), antioxidant activity, some biochemical parameters and histopathological changes in arsenic-exposed mice. Forty Swiss albino male mice were divided into five equal groups. Group I (control group) was given normal diet and tap water for 28 days. Group II (arsenic group) was given normal diet and 100 mg/L arsenic along with drinking water for 28 days. Groups III-V were given three different doses of Ys (50, 100 and 200 mg/kg) in supplemented diet and arsenic (100 mg/L) along with drinking water throughout the entire period of 28 days. The arsenic significantly increased serum biochemical parameters and malondialdehyde levels in blood and tissue. However, arsenic significantly decreased tissue glutathione concentration, erythrocyte superoxide dismutase and catalase activities. In contrast, dietary supplementation of Ys, in a dose-dependent manner, resulted in reversal of arsenic-induced oxidative stress, LPO and activities of antioxidant enzymes. Moreover, Ys also exhibited protective action against the arsenic-induced focal gliosis and hyperemi in brain, necrosis and degeneration in liver, degeneration and dilatation in Bowman's capsule of kidney and hyaline degeneration in heart tissue of mice. Consequently, our results demonstrate that Ys especially high-dose supplementation in diet decreases arsenic-induced oxidative stress and enhances the antioxidant defence mechanism and regenerate of tissues in Swiss albino mice.",
Arsenic,1353363,Effects of Competing Anions and Iron Bioreduction on Arsenic Desorption Abstract: ,
Arsenic,1797750,"Down-regulated GFAP?: a major player in heavy metal induced astrocyte damage Abstract: Exposure to a mixture of As, Pb and Cd induces apoptosis and morphological alterations in the cortical astrocytes of rat brain. The levels of the glial fibrillary acidic protein (GFAP) undergo a reduction. The GFAP exists in several isoforms, viz., ?, ?, ?, ? and ?. However, contribution of the isoforms towards astrocyte damage is not understood. We investigated the effect of the metal mixture (MM) on the expression profiles of mRNAs encoding the GFAP isoforms in astrocytes. The MM was administered in drinking water to developing rats till postnatal day (PD) 60. We observed a fall (10.20?±?1.04%, 18.91?±?2.12% and 30.26?±?3.21% at PD24, PD45 and PD60 respectively) in GFAP?. This may have been compensated by a rise in ?, ?, and ?. The GFAP? remained unchanged. To determine the role of the GFAP?, we silenced its gene using SiRNA technology in the rat primary astrocytes. We observed a 23.73?±?1.56% increase in the number of apoptotic cells. The cleaved PARP and Bax levels increased by 2.48?±?0.14-fold and 3.73?±?0.23-fold respectively, and the Bcl-2 and Bcl-xl decreased by 2.38?±?0.08-fold and 1.76?±?0.09-fold respectively. The change was comparable to the cells treated with MM. Moreover, silencing the GFAP? gene induced a reduction in the area (6.19?±?0.18-folds), perimeter (12.65?±?1.68-folds) and the number of processes (5.88?±?1.5-folds) in the astrocytes, which closely matched the MM-treated ones. Taken together, these observations are the first to show that MM disturbs the composition of the GFAP isoforms, and a suppressed GFAP? promotes apoptosis in the matured rat astrocytes.",
Arsenic,16120,"Exposure to arsenic and lead and neuropsychological development in Mexican children Abstract: This cross-sectional study examined the effects of chronic exposure to lead (Pb), arsenic (AS) and undernutrition on the neuropsychological development of children. Two populations chronically exposed to either high (41 children) or low (39 children) levels of As and Pb were analyzed using the Wechsler Intelligence Scale for Children, Revised Version, for Mexico (WISC-RM). Geometric means of urinary arsenic (AsU) and lead in blood (PbB) were 62.9+/-0.03 (microgAs/g creatinine) and 8.9+/-0.03 (microg/dl) for the exposed group and 40.2+/-0.03 (microgAs/g creatinine) and 9.7+/-0.02 (microg/dl) for the reference group. The height for age index (HAI) was used as an indicator of chronic malnutrition and sociodemographic information was obtained with a questionnaire. Lead and arsenic were measured by atomic absorption spectrophotometry. Data on full, verbal, and performance intelligence quotients (IQ) scores, long-term memory, linguistic abstraction, attention span, and visuospatial organization were obtained through the WISC-RM. After controlling for significant potential confounders verbal IQ (P<0.01) decreased with increasing concentrations of AsU. The HAI correlated positively with full-scale and performance IQ (P<0.01). Higher levels of AsU were significantly related to poorer performance on WISC-RM factors examining long-term memory and linguistic abstraction, while lower scores in WISC-RM factors measuring attention were obtained at increasing values of PbB. Our results suggest that exposure to As and chronic malnutrition could have an influence on verbal abilities and long-term memory, while Pb exposure could affect the attention process even at low levels.",
Arsenic,1326803,"The protective role of intracellular GSH status in the arsenite-induced vascular endothelial dysfunction Abstract: In this study, we used porcine aortic endothelial cells (PAECs) as an in vitro system to investigate the role of intracellular GSH status in arsenite-induced vascular endothelial damage. Exposure of PAECs to l-buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase (gamma-GCS), markedly enhanced the arsenite-induced cytotoxicity. The data implied that intracellular GSH might play an important role in protection of PAECs from arsenite-induced cytotoxicity. Low concentrations of arsenite exposure increased intracellular GSH concentrations, whereas high concentrations of arsenite exposure decreased intracellular GSH concentrations. We further modulated intracellular GSH concentration by using GSH modulators. N-Acetyl cysteine (NAC) and l-cystine (oxidized l-cysteine), by up-regulating intracellular GSH concentrations, were shown to protect PAECs from arsenite-induced cytotoxicity. On the other hand, BSO and monosodium glutamate (MSG), which down-regulated the intracellular GSH concentrations, further potentiated arsenite-induced cytotoxicity. Moreover, exposure of PAECs to NAC alleviated the arsenite-induced JNK/AP-1 activation and apoptosis, whereas exposure of PAECs to BSO enhanced the arsenite-induced JNK/AP-1 activation and apoptosis. These results indicated that an increase in GSH content represented one of the detoxification mechanisms responding to arsenite exposure and probably played critical roles in the regulation of stress-response signaling molecules as well as in protection of PAECs from arsenite attack.",
Arsenic,1340237,"Heavy metal accumulation by recombinant mammalian metallothionein within Escherichia coli protects against elevated metal exposure Abstract: Metallothioneins (MTs) are ubiquitous metal-binding, cysteine-rich, small proteins known to provide protection against toxic heavy metals such as cadmium. In an attempt to increase the ability of bacterial cells to accumulate heavy metals, sheep MTII was produced in fusion with the maltose binding protein (MBP) and localized to the cytoplasmic or periplasmic compartments of Escherichia coli. For all metals tested, higher levels of bioaccumulation were measured with strains over-expressing MBP-MT in comparison with control strains. A marked bioaccumulation of Cd, As, Hg and Zn was observed in the strain over-expressing MBP-MT in the cytoplasm, whereas Cu was accumulated to higher levels when MBP-MT was over-expressed in the periplasm. Metal export systems may also play a role in this bioaccumulation. To illustrate this, we over-expressed MBP-MT in the cytoplasm of two mutant strains of E. coli affected in metal export. The first, deficient in the transporter ZntA described to export numerous divalent metal ions, showed increasing quantities of Zn, Cd, Hg and Pb being bioaccumulated. The second, strain LF20012, deficient in As export, showed that As was bioaccumulated in the form of arsenite. Furthermore, high quantities of accumulated metals, chelated by MBP-MT in the cytoplasm, conferred greater metal resistance levels to the cells in the presence of added toxic metals, such as Cd or Hg, while other metals showed toxic effects when the export systems were deficient. The strain over-expressing MBP-MT in the cytoplasm, in combination, with disruption of metal export systems, could be used to develop strategies for bioremediation.",
Arsenic,2337217,"Are different soil metals near the homes of pregnant women associated with mild and severe intellectual disability in children? Abstract: <strong>AIM: </strong>We explored the association of relatively low concentrations of metals in the soil proximal to maternal residence during pregnancy, with intellectual disability. We hypothesized different metals would be associated with mild versus severe intellectual disability.<br /><br /><strong>METHOD: </strong>We used a mixed methods design, starting with a retrospective cohort from 1996 to 2002, of 10 051 pregnant mothers, soil sampling in the areas where these mothers resided during pregnancy, and follow-up of their children to determine if there was an intellectual disability outcome. We tested the soil and then predicted the soil concentration at the maternal homes, and modeled the association with the severity of the child's intellectual disability.<br /><br /><strong>RESULTS: </strong>We found a significant positive association between mild intellectual disability and soil mercury (p=0.007). For severe intellectual disability, there was a significant positive association with the soil arsenic and lead (p=0.025).<br /><br /><strong>INTERPRETATION: </strong>This is the first report of the differential impact of metals in soil and severity of intellectual disability in children. Soil mercury concentration in the area the mother lived during pregnancy is associated with significantly increased odds of mild intellectual disability; a combination of arsenic and lead is associated with significantly increased odds of severe intellectual disability. These associations are present when controlling for maternal, child, and neighborhood characteristics.",
Arsenic,1032058,"Characterization of a new human papillomavirus (HPV 41) from disseminated warts and detection of its DNA in some skin carcinomas Abstract: A new human papillomavirus type (HPV 41), distantly related to known HPV prototypes, was isolated from a patient with disseminated facial, peri-anal and foot warts (epidermodysplasia verruciformis was not diagnosed). The viral DNA was molecularly cloned in 2 BamH1 restriction fragments with sizes of 6.5 kb and 0.98 kb, respectively. The classification of this cloned DNA as a new type is based on the degree of cross-hybridization with 40 HPV types under conditions of varying stringency. A total of 106 benign and malignant skin lesions, as well as 71 malignant tumours of different origins, were screened for the presence of HPV-related sequences. In 2 out of 10 squamous-cell carcinomas and in 1 of 3 arsenic keratoses HPV 41 DNA sequences could be detected.",
Arsenic,8744,"Worker exposure to arsenic in Florida grapefruit spray operations Abstract: Dermal and respiratory exposures of arsenic (7440382) were measured in workers involved in mixing, loading, and applying lead-arsenate (301042) sprays to grapefruit trees. Five males from two citrus grower cooperatives participated in the study. Crew 1 consisted of one supplier who mixed the concentrated pesticides and filled the spray tank, and two applicators operating tractor drawn air blast sprayers. Applicators applied a 0.1 percent spray mixture of lead-arsenate at the rate of 4.7 kilograms active ingredient per hectare. Arsenic exposure was monitored for 9 days during the 5 week spray season. Crew 2 consisted of one supplier and one applicator. Arsenic exposure was monitored in a similar manner. Dermal exposure to hands was estimated from arsenic residues on gloves. Respirators with filter pads were used to assess respiratory exposure. Arsenic amounts were also detected in urine samples. For both groups, legs, feet, and hands received the highest percent of exposure. Applicator exposure was greater than supplier exposure for head, neck, back, chest, and arms. A comparison of the two groups showed that crew 2 had a 3:1 elevation in mean total body arsenic exposure. Suppliers had significantly greater arsenic excretion rates and concentrations than did applicators. The authors conclude that if spray material is more concentrated, a worker is correspondingly exposed to greater amounts of arsenic.",
Arsenic,1508576,"A metal mixture induces transformation upon antioxidant depletion in a hepatic cell line Abstract: Introduction. Metals are ubiquitous soil, air, and water pollutants. A mixture of arsenic cadmium and lead, in particular, has commonly been found in the vicinity of smelter areas. The mixture of As-Cd-Pb has been shown to be carcinogenic, and transforming potential and oxidative stress have been proposed as principal mechanisms involved in this process. The aim of this work was to explore the role of the antioxidant barrier in the establishment of cell transformation upon chronic exposure to a metal mixture containing 2 ?M NaAsO2, 2 ?M. CdCl2, and 5 ?M Pb(C2H3O2)2•3H2O in WRL-68 cells-a non-transformed human hepatic cell line. Material and methods. In this study, we used a WRL-68 cell model of human embryonic hepatic origin treated with antioxidant inhibitors (L-Buthionine-sulfoxamine and aminotriazole) to test the role of the antioxidant barrier in the establishment of cell transformation upon chronic exposure to a metal mixture of As-Cd-Pb (2 ?M NaAsO2, 2 ?M CdCl2 and 5 ?M Pb(C2H3O2)2•3H2O). We evaluated oxidative damage markers, including reactive oxygen species, lipid peroxidation, and genotoxicity, as well as antioxidant response markers, including glutathione concentration, catalase activity, and superoxide dismutase activity, wich promote morphological transformation, which can be quantified by foci formation. Results. As expected, we found an increase in the intracellular concentration of the metals after treatment with the metal mixture. In addition, treatment with the metal mixture in addition to inhibitors resulted in a large increase in the intracellular concentration of cadmium and lead. Our results describe the generation of reactive oxygen species, cytotoxicity, genotoxicity, and oxidative damage to macromolecules that occurred exclusively in cells that were morphologically transformed upon exposure to a metal mixture and antioxidant barrier inhibition. Conclusion. Our results show the importance of the antioxidant barrier role in the protection of cellular integrity and the transformation potential of this metal mixture via free radicals.",
Arsenic,2343560,"Chemical composition and biological value of proteins of the yeast Yarrowia lipolytica growing on industrial glycerol Abstract: The aim of this study was to evaluate the chemical composition and biological value of proteins from the yeast, Yarrowia lipolytica, after cultivation on glycerol, a waste product obtained in the production of biofuel from rapeseed. In the tested material we determined moisture, crude protein, ether extract, nitrogen-free extract (NFE), ash, calcium, phosphorus, cadmium, mercury, arsenic, amino acids and fatty acids. The biological value of Y. lipolytica and Saccharomyces cerevisiae proteins was determined with laboratory rats by two methods: the growth method (protein efficiency ratio standardized for casein, PERstand; net protein retention, NPR) and the Thomas -Mitchell method (biological value, BV; true digestibility, TD). The protein content of Y. lipolytica [467 g kg(-1) dry matter (DM)] was similar to that of S. cerevisiae (479 g kg(-1) DM). Of particular interest was the almost 30-times higher crude fat content in Y. lipolytica (200 g kg(-1) DM) than in S. cerevisiae (6.7 g kg(-1) DM). Yarrowica lipolytica cells accumulated substantial amount of fat in which more than 90% of fatty acids were unsaturated fatty acids with a considerable share of polyunsaturated fatty acids (34%). The low share of sulfur amino acid of Y. lipolytica (2.05 g 16g(-1) N) and S. cerevisiae (2.32 g 16g(-1) N) limited the nutritional value of the protein of the studied yeast. The biological value of proteins as assessed by the growth method (PER, NPR) did not differ between the two yeast species. Finally, Y. lipolytica was a rich source of highly digestible ether extract (over 57%).",
Arsenic,1936180,"Procedia Earth and Plantetary Science Impact of geothermal wastewater drainage on arsenic species in environmental media: a case study at the Yangbajing geothermal field, Tibet, China Abstract: ",
Arsenic,710834,"Arsenic inhibits neurite outgrowth by inhibiting the LKB1-AMPK signaling pathway Abstract: Arsenic (As) is an environmental pollutant that induces numerous pathological effects, including neurodevelopmental disorders.<br /><br /> We evaluated the role of the LKB1-AMPK pathway in As-induced developmental neurotoxicity using Neuro-2a (N2a) neuroblastoma cells as a model of developing neurons.<br /><br /> The addition of low concentrations of As (&lt;or= 5 microM) during differentiation caused an inhibitory effect on the neurite outgrowth in N2a cells in the absence of cell death. Activation of adenosine monophosphate-activated kinase (AMPK) induced by retinoic acid in differentiating cells was blocked by As. Pretreatment with the AMPK-specific activator 5-aminoimidazole-4-carboxamide riboside or overexpression of a constitutively active AMPK-alpha1 plasmid reversed As-induced inhibition of neurite outgrowth. The activation of LKB1 (serine/threonine kinase 11), a major AMPK kinase, was also suppressed by As by inhibiting both the phosphorylation and the translocation of LKB1 from nucleus to cytoplasm. Antioxidants, such as N-acetyl cysteine and superoxide dismutase, but not catalase, protected against As-induced inactivation of the LKB1-AMPK pathway and reversed the inhibitory effect of As on neurite outgrowth.<br /><br /> Reduced neurite outgrowth induced by As results from deficient activation of AMPK as a consequence of a lack of activation of LKB1. Oxidative stress induced by As, especially excessive superoxide, plays a critical role in blocking the LKB1-AMPK pathway. Our studies provide insight into the mechanisms underlying As-induced developmental neurotoxicity, which is important for designing a new strategy for protecting children against this neurotoxic substance.",
Arsenic,1351590,"LIMITED ARSENIC DISPERSION IN SEA-WATER, SEDIMENTS, AND BIOTA NEAR A CONTINUOUS SOURCE Abstract: HEEP COPYRIGHT: BIOL ABS. Moreton's Harbour, Newfoundland (Canada), has been exposed to As-bearing drainage and leaching from a stibnite mine for at least 38 yr and possibly longer than 84 yr. Measurements of inorganic As in seawater and sediments and total As in some marine organisms revealed a very limited influence of continuous exposure to As in the small harbor. As concentrations in surface water declined to normal within 200 m and in sediments within 50 m. Animals did not show significantly higher levels near the mine, with the exception of the sea urchin Strongylocentrotus droebachiensis, which accumulated significantly higher levels of As adjacent to the mine site.",
Arsenic,1070497,"Arsenic accumulation and speciation in the submerged macrophyte Ceratophyllum demersum L Abstract: INTRODUCTION: Ceratophyllum demersum L. is a widespread submerged macrophyte in aquatic environments. METHODS: Simulation experiments were conducted in the laboratory to investigate arsenic (As) accumulation, speciation, and efflux of C. demersum exposed to arsenate and arsenite solutions. RESULTS: Plant shoots showed a significant accumulation of As with a maximum of 862 and 963 ?g As g(-1) dry weight after 4 days of exposure to 10 ?M arsenate and arsenite, respectively. Regardless of whether arsenate or arsenite was supplied to the plants, arsenite was the predominant species in plant shoots. Furthermore, a dramatically higher influx rate of arsenate compared with arsenite was observed in C. demersum exposed to As solutions without the addition of phosphate (P). Arsenate uptake was considerably inhibited by P in this study, suggesting that arsenate is taken up by C. demersum via the phosphate transporters. However, arsenite uptake was unaffected by P and markedly reduced in the presence of glycerol and antimonite (Sb), indicating arsenite shares the aquaporin transport pathway. In addition, C. demersum rapidly reduces arsenate to arsenite in the shoot of the plant and extrudes most of them (&gt;60 %) to the external solutions. The efflux of arsenite was much higher than that of arsenate; the former is supposed to be both active and passive processes, and the latter through passive leakage. CONCLUSION: C. demersum is a strong As accumulator and an interesting model plant to study As uptake and metabolism due to the lack of a root-to-shoot translocation barrier.",
Arsenic,737233,"Effects of arsenite on estrogen receptor-alpha expression and activity in MCF-7 breast cancer cells Abstract: To determine whether arsenite has estrogen-like activities, the effects of this compound on estrogen receptor-alpha (ERalpha) and other estrogen-regulated genes were measured in the human breast cancer cell line MCF-7. Treatment of cells with 1 microM arsenite resulted in a 60% decrease in the amount of ERalpha and in a parallel decrease of 40% in ERalpha messenger RNA. Progesterone receptor concentration increased 22-fold after arsenite treatment. pS2 messenger RNA also increased 2. 1-fold after treatment. The induction of progesterone receptor and pS2 was blocked by the antiestrogen ICI-182,780. In transient cotransfection experiments of wild-type ERalpha and an estrogen response element-reporter construct, arsenite stimulated chloramphenicol acetyltransferase (CAT) activity. In growth assays, arsenite significantly stimulated the proliferation of MCF-7 cells compared with cells grown in estrogen-depleted medium. Addition of an antiestrogen blocked growth stimulation by arsenite. In binding assays, arsenite blocked the binding of estradiol to ERalpha (Ki = 5 +/- 0.5 nM; n = 3), suggesting that the compound interacts with the hormone-binding domain of the receptor. To determine whether interaction of arsenite with the hormone-binding domain results in receptor activation, COS-1 cells were transiently cotransfected with the chimeric receptors GAL-ER, which contains the hormone-binding domain of ERalpha and the DNA-binding domain of the transcription factor GAL4, and a GAL4-responsive CAT reporter gene. Treatment of cells with estradiol or arsenite resulted in a 4-fold increase in CAT activity. The effects of arsenite on the chimeric receptor were blocked by the antiestrogen, suggesting that arsenite activates ERalpha through an interaction with the hormone-binding domain of the receptor. Transfection assays with ERalpha mutants identified C381, C447, H524, and N532 as interaction sites of arsenite with the hormone-binding domain.",
Arsenic,1015862,"Arsenic in cooked rice: effect of chemical, enzymatic and microbial processes on bioaccessibility and speciation in the human gastrointestinal tract Abstract: Rice, used as staple food for half of the world population, can easily accumulate arsenic (As) into its grain, which often leads to As contamination. The health risk induced by presence of As in food depends on its release from the food matrix, i.e., its bioaccessibility. Using an in vitro gastrointestinal simulator, we incubated two types of cooked rice (total As: 0.389 and 0.314 mg/kg). Arsenic bioaccessibility and speciation changes were determined upon gastrointestinal digestion. Washing with deionized water and cooking did not result in changes of As speciation in the rice although the arsenic content dropped by 7.1-20.6%. Arsenic bioaccessibility of the cooked rice in the small intestine ranged between 38 and 57%. Bioaccessibility slightly increased during digestion in the simulated small intestine and decreased with time in the simulated colon. Significant speciation changes were noted in the simulated colon, with trivalent monomethylarsonate (MMA(III)) becoming an important species.",
Arsenic,1519224,Detoxification of Arsenite through Adsorption and Oxidative Transformation on Pyrolusite Abstract: ,
Arsenic,1508694,"Arsenic and Mercury in Native Aquatic Bryophytes: Differences Among Species Abstract: This study investigated the capacities of five species of aquatic bryophytes to accumulate As and Hg from their natural habitats in rivers in Galicia (NW Spain). The distributions of the concentrations of both elements in all species were skewed to the right, with a higher incidence of extreme values in the As data, which may indicate a greater degree of contamination by this metalloid. There were no significant differences in the accumulation of either of the elements between the different species studied, which justifies their combined use as biomonitors of As and Hg, at least in the study area.",
Arsenic,1255513,"Changes in the synaptic structure of hippocampal neurons and impairment of spatial memory in a rat model caused by chronic arsenite exposure Abstract: Many epidemiological studies and in vitro experiments have found that chronic arsenic exposure may influence memory formation. The goal of this study was to create an animal model of memory impairment induced by chronic arsenite exposure and to study the underlying mechanisms. Sixty male Sprague-Dawley (SD) male rats were randomly divided into a control group, a low-dose sodium arsenite exposure group and a high-dose sodium arsenite exposure group. Sodium arsenite was administered by adding it to drinking water for 3 months. Then, the spatial memory of the rats was examined with Morris water maze and Y maze. The concentration of arsenic in the blood and the brain was determined by an atomic fluorescence absorption spectrometer. The ultra-structure of hippocampal neurons was observed by an electron microscope. Timm staining was used for observing mossy fibers. We found that the concentration of arsenic in the blood and the brain increased in a dose-response manner (P<0.05). The performance of rats in the arsenite exposed group (15mg/kg) was significantly impaired in the Morris water maze and Y maze tasks than those in the control group (P<0.05). Sodium arsenite exposure resulted in abnormal structural changes in the myelin sheaths of nerve fibers and decreases in the terminals of mossy fibers. Together, chronic sodium arsenite exposure through drinking water results in detrimental changes in the neuronal synapses, which may contribute to the arsenite-induced impairment of spatial memory.",
Arsenic,1338673,"Metabolism of inorganic arsenic in intestinal epithelial cell lines Abstract: This study evaluates the metabolism of inorganic arsenic (iAs) [As(III) and As(V)] in human intestinal cells as a function of cell type, differentiation stage, type of support used for cell growth, and exposure time. Additionally, mRNA expression of arsenic (+3 oxidation state) methyltransferase (AS3MT) was evaluated. For this purpose, Caco-2 (absorptive type) and HT29-MTX (goblet type) cells were exposed at various stages of differentiation (5, 15, and 21 days post-seeding) with different concentrations of As(III) and As(V) (1 and 10 ?M) and exposure times (24, 48, and 72 h), using multiwell plates or Transwells. The results show that both cell lines express AS3MT at all stages of differentiation and in all culture conditions. Caco-2 cells are capable of metabolizing iAs, As(III) metabolism being greater than that observed for As(V). Metabolism depends on the stage of differentiation, reaching 36% after 48 h of exposure of differentiated cells (15 days post-seeding), with the monomethylated species as the major metabolite. Analysis of the cell interior shows that the metabolites are present predominantly in trivalent form. The type of support is also an important factor, metabolism being greater in multiwell plates than in Transwells (36 ± 6% vs 11 ± 3%). Neither monomethylated arsenic species (MMA) nor dimethylated arsenic species (DMA) are detected in HT29-MTX cells after exposure to iAs, possibly because most of the iAs is retained in the mucus layer and does not internalize. These results show that the intestine is an organ that may take part in presystemic metabolism of iAs. Moreover, the transformation of iAs into more toxic species indicates the need to study the effects of this species on the intestinal epithelium.",
Arsenic,1381034,"Prognosis of the stability of arsenic in the biotop of the brown-coal dump Abstract: In the nature there is a large number of various microorganisms which participate in the process of transformation of minerals and other materials, in their corrosion, disintegration decomposition or even formation of new components. Many of the microorganisms gain the energy for their metabolic processes trough oxidation of anorganic compounds. Interaction of microorganisms or their metabolites with deposited components, which may be toxid, can take place directly in the dump biotop. In fly-ashes produced by burning the Slovak brown coal a higher arsenic content is present, the arsenic in the original coal being bound in a very stable FeAsS compound (arsenopyrite). However this compound is decomposed by burning and so we were interested in the stability of newly formed arsenic compounds found in the fly-ash. Their stability was tested by leaching experiments in an environment of nutrient medium for bacteria Thiobacillus ferrooxidans 9KA (pH 1.5) at a concentration of cells 7x10 ml and simultaneously also without bacterial culture at the same condition. Apart from this, the extraction of arsenic from fly-ash was monitored also in the environment of metabolites of fungi Aspergillus niger (citric acid) at pH 1.8.",
Arsenic,1936194,Procedia Chemistry Realgar and Light Abstract: ,
Arsenic,8493,"Effect of the combined action of selenium and arsenic on suspension culture of mice fibroblasts Abstract: The protective influence of arsenic against the toxic action of selenium has been tested on suspension cultures of mice fibroblasts LA 115. The growth of the cells was observed after the isolated and combined action of sodium arsenite NaAsO2 and sodium selenite Na2SeO3. The concentration range of both substances in cultivation medium MEm (USOL) was 10(-5) -10(-11)M. The growth of treated cultures was analyzed daily during 5 days of exposure. From the results obtained, growth curves of the cell cultures were constructed and analyzed. The results of every determination were evaluated in relation to the corresponding control culture. The results obtained demonstrate that decreasing concentrations of arsenic enhanced its protective effect in the range of the concentrations used. In contrast, a low protective effect of selenium against arsenic was noted in the concentrations employed. The cell cultures have proved to be very suitable for toxicological studies of the combined effects of different substances.",
Arsenic,627230,"Proteomic and biochemical analyses of in vitro carcinogen-induced lung cell transformation: Synergism between arsenic and benzo[a]pyrene Abstract: Chronic coexposures to carcinogens inorganic arsenic and benzo[a]pyrene (B[a]P) are common in the living environment. However, little is known about their effects exerted at the proteome level. Our previous study in rat lung epithelial cells showed that cell transformation frequency increased by more than 100-fold when arsenic was given in combination with B[a]P than cells either exposed to arsenic or B[a]P alone. This demonstrated a synergism between them. Here, we reported that alterations to the proteome varied and were more pronounced in the transformed cells that were exposed to a combination of arsenic and B[a]P than to B[a]P and much less to arsenic alone when compared to passage-matched control cells. In general, three proteins belonging to intermediate filaments were found to be significantly down-regulated and six proteins belonging to antioxidative stress-, chaperone-, and glycolytic proteins were up-regulated in these transformed cells. These transformed cells were also associated with an increase of proliferation and de-differentiation. Taken together, our findings suggest that although arsenic or B[a]P alone is sufficient to induce cell transformation and alter the proteome to a similar extent, the effects of coexposure are much more pronounced. This further substantiates the notion that these carcinogens act in concert during cocarcinogenesis.",
Arsenic,1677556,"Arsenic species and uptake in amphibians (Rana clamitans and Bufo americanus) Abstract: Total arsenic concentrations and the chemical form, or species, of arsenic were determined in amphibians (Rana clamitans and Bufo americanus) collected from a site with elevated arsenic concentrations in Nova Scotia, Canada. Frog legs had significantly elevated total arsenic concentrations at a contaminated site when compared with a nearby background site and a calculation of the estimated daily intake rates of arsenic indicates that both diet (invertebrate intake) and water absorption are important sources of arsenic for these adult organisms. Body burdens of tetramethylarsonium were similar for both the contaminated and background site, with up to 50% of the total arsenic contained in frog legs in the form of the tetramethylarsonium ion.",
Arsenic,734290,"Immunotoxicological investigation in rats dosed repeatedly with combinations of cypermethrin, As(III), and Hg(II) Abstract: The effects of the combined exposure of cypermethrin (CY), NaAsO2 (As), and HgCl2 (Hg) were investigated in male Wistar rats following 4 weeks of oral exposure. Standard toxicological (body weight gain, organ weights of brain, thymus, heart, lung, liver, kidneys, adrenals, testes, and popliteal lymph node), haematological (white blood cell, red blood cell, haematocrit, MCV-mean volume of red blood cells, and cell content of the femoral bone marrow), and immune function (IgM-PFC response, delayed type hypersensitivity (DTH) reaction) parameters were measured. The two doses selected for the combination were: a high (H) dose equal to lowest observed effect level determined in preliminary experiments (CY(H)=55.4 mg/kg, As(H)=13.3 mg/kg, Hg(H)=3.20 mg/kg), and a low (L) dose which was ineffective (non-observed effect level); CY(L)=11.1 mg/kg, As(L)=3.33 mg/kg, Hg(L)=0.40 mg/kg). CY(H) was combined with As(L) or Hg(L), and the H doses of the heavy metals were combined with CY(L). Beside vehicle control, the H dose components of the combinations were also used as internal controls. The main finding of this study was that certain combinations, when compared to H dose internal control, significantly altered the body weight gain (As(H)+CY(L)), the relative weight of adrenals and popliteal lymph node (CY(H)+As(L) and CY(H)+Hg(L)), the cell content of the femoral bone marrow (CY(H)+Hg(L)), and the time course of DTH reaction (CY(H)+As(L)). According to the present results, combined exposure with CY and the heavy metals investigated can modify the toxicity and/or the functional detection limit of the single substances.",
Arsenic,1031514,"Urinary arsenic speciation and its correlation with 8-OHdG in Chinese residents exposed to arsenic through coal burning Abstract: In contrast to arsenicosis caused by consumption of water contaminated by naturally occurring inorganic arsenic, human exposure to this metalloid through coal burning has been rarely reported. In this study, arsenic speciation and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in urine were determined in the Chinese residents exposed to arsenic through coal burning in Guizhou, China, an epidemic area of chronic arsenic poisoning caused by coal burning. The urinary concentrations of inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and total arsenic (tAs) of high-arsenic exposed subjects were significantly higher than those of low-arsenic exposed residents. A biomarker of oxidative DNA damage, urinary 8-OHdG level was significantly higher in high-arsenic exposed subjects than that of low exposed. Significant positive correlations were found between 8-OHdG levels and concentrations of iAs, MMA, DMA and tAs, respectively. In addition, a significant negative correlation was observed between 8-OHdG levels and the secondary methylation ratio (DMA/(MMA + DMA)). The results suggest that chronic arsenic exposure through burning coal rich in arsenic is associated with oxidative DNA damages, and that secondary methylation capacity is potentially related to the susceptibility of individuals to oxidative DNA damage induced by arsenic exposure through coal burning in domestic living.",
Arsenic,2278459,"Geochemistry of Tungsten and Arsenic in Aquifer Systems: A Comparative Study of Groundwaters from West Bengal, India, and Nevada, USA Abstract: Tungsten (W) concentrations were measured along with arsenic (As) in groundwaters from the Murshidabad district of West Bengal, India. Tungsten concentrations range from 0.8 to similar to 8 nmol kg(-1) (0.15-1.5 mu g kg(-1)) in the circumneutral pH (average pH similar to 7.3) Murshidabad groundwaters, and attain concentrations as high as 14 nmol kg(-1) (2.5 mu g kg(-1)) in local ponds (n=2). Total dissolved As concentrations (As-T) range from 0.013 to 53.9 mu mol kg(-1) (&lt;1 to 4,032 mu g kg(-1)), and As(III) predominates in Murshidabad groundwaters accounting for 70 %, on average, of As in solution. Tungsten concentrations in Murshidabad groundwaters are low compared to alkaline groundwaters (pH&gt;8) from the Carson Desert in Western Nevada, USA, where W concentrations are reported to reach as high as 4,036 nmol kg(-1) (742 mu g kg-1). Although W is positively correlated with As in groundwaters from the Carson Desert, it is not correlated with As-T or As(III) in Murshidabad groundwaters, but does exhibit a weak relationship with As(V) in these groundwaters. Surface complexation modeling indicates that pH related adsorption/desorption can explain the geochemical behavior of W in Murshidabad groundwaters. However, the model does not predict the high As concentrations observed in Murshidabad groundwaters. The high As and low W concentrations measured in Murshidabad groundwaters indicate that either As and W originate from different sources or are mobilized by different biogeochemical processes within the Murshidabad aquifers. Mobilization of As in Murshidabad groundwaters is presumed to reflect reductive dissolution of Fe(III) oxides/oxyhydroxides and release of sorbed and/or coprecipitated As to the groundwaters. Multivariate statistical analysis of groundwater composition data indicate that W is associated with Mn and Cl-, which may point to a Mn oxide/oxyhydroxide, clay mineral, and/or apatite source for Win the Murshidabad sediments.",
Arsenic,2088356,"Calmodulin-CaMKII mediated alteration of oxidative stress: Interplay of the cAMP/PKA-ERK 1/2-NF-kappa B-NO axis on arsenic-induced head kidney macrophage apoptosis Abstract: Using the head kidney macrophages (HKM) from catfish (Clarias batrachus) we earlier demonstrated the role of calcium (Ca2+) and its dependent neutral protease calpain in arsenic-induced apoptosis. Here, we report the role of the CaM-CaMKII axis as an initiator of the process. With the help of specific assay kits and inhibitors we document the pro-apoptotic role of CaM and CaMKII in arsenic-induced HKM apoptosis. CaM-induced CaMKII activity influenced superoxide ion production in exposed cells with a consequent increase in intracellular cAMP levels. Using H-89, the specific inhibitor for PKA, we show for the first time the pro-apoptotic role of the cAMP/PKA pathway in arsenic-induced HKM apoptosis. We report the cAMP/PKA pathway to be critical for initiating downstream activation of MAPKs, namely ERK 1/2. The superoxide ions generated due to arsenic-stress also induce NF-kappa B activation in HKM. Inducible NOS activity and consequent NO production were evident in the exposed HKM and our study implicates the involvement of ERK 1/2 and NF-kappa B in the process. Arsenic exposure alters mitochondrial membrane potential, releases cytochrome C and activates caspase-9 leading to caspase-3 mediated apoptosis of HKM. Our findings, thus, provide insight into the underlying mechanism of arsenic toxicity and indicate that HKM could serve as an important in vitro model for immunotoxicity assays.",
Arsenic,1019062,"Application of modelling techniques to the planning of in vitro arsenic kinetic studies Abstract: A kinetic model describing the hepatic methylation of arsenite [As(III)] was developed on the basis of limited data from in vitro mechanistic studies. The model structure is as follows: sequential enzymic methylation of arsenite to its monomethylated (MMA) and dimethylated (DMA) products by first-order and Michaelis-Menten kinetics, respectively; uncompetitive inhibition of the formation of DMA by As(III); and first-order reversible binding of As(III), MMA and DMA to cytosolic proteins. Numerical sensitivity analysis was used to evaluate systematically the impact of changes in input parameters on model responses. Sensitivity analysis was used to investigate the possibility of designing experiments for robust testing of the uncompetitive inhibition hypothesis, and for further refining the model. Based on the sensitivity analysis, the MMA concentration is the most important response on which to focus. The parameters V(max) and k(i) can be reliably estimated by using the same concentration time-course data at intermediate initial arsenite concentrations of 1--5microM at 30 +/- 5 minutes. K(m) must be estimated independently of V(max), since the two parameters are highly correlated at all times, and the optimal experimental conditions would include lower initial concentrations of arsenite (0.1--0.5microM) and earlier time-points (about 8--18 minutes). The use of initial arsenite concentrations much above 5microM would not yield additional useful information, because the sensitivity coefficients for MMA, protein-bound MMA, DMA and protein-bound DMA tend to become extremely small or exhibit erratic trends. Overall trends in the sensitivity analysis indicated the desirability of performing measurements at times shorter than 60 minutes. This work demonstrates that physiological modelling and sensitivity analysis can be efficient tools for experimental planning and hypothesis testing when applied in the earliest phases of kinetic model development, thus allowing more-efficient and more-directed experimentation, and minimising the use of laboratory animals.",
Arsenic,627502,"Polymorphisms in nucleotide excision repair genes, arsenic exposure, and non-melanoma skin cancer in New Hampshire Abstract: BACKGROUND: Arsenic exposure may alter the efficiency of DNA repair. UV damage is specifically repaired by nucleotide excision repair (NER), and common genetic variants in NER may increase risk for non-melanoma skin cancer (NMSC). OBJECTIVE: We tested whether polymorphisms in the NER genes XPA (A23G) and XPD (Asp312Asn and Lys751Gln) modify the association between arsenic and NMSC. METHODS: Incident cases of basal and squamous cell carcinoma (BCC and SCC, respectively) were identified through a network of dermatologists and pathology laboratories across New Hampshire. Population-based controls were frequency matched to cases on age and sex. Arsenic exposure was assessed in toenail clippings. The analysis included 880 cases of BCC, 666 cases of SCC, and 780 controls. RESULTS: There was an increased BCC risk associated with high arsenic exposure among those homozygous variant for XPA [odds ratio (OR) = 1.8; 95% confidence interval (CI), 0.9-3.7]. For XPD, having variation at both loci (312Asn and 751Gln) occurred less frequently among BCC and SCC cases compared with controls (OR = 0.8; 95% CI, 0.6-1.0) for both case groups. In the stratum of subjects who have variant for both XPD polymorphisms, there was a 2-fold increased risk of SCC associated with elevated arsenic (OR = 2.2; 95% CI, 1.0-5.0). The test for interaction between XPD and arsenic in SCC was of borderline significance (p < 0.07, 3 degrees of freedom). CONCLUSIONS: Our findings indicate a reduced NMSC risk in relation to XPD Asp312Asn and Lys751Gln variants. Further, these data support the hypothesis that NER polymorphisms may modify the association between NMSC and arsenic.",
Arsenic,2305128,"Modeling metal bioaccumulation and tissue distribution in Killifish (Fundulus heteroclitus) in three contaminated estuaries Abstract: The present study experimentally assessed the uptake, loss, and resulting tissue distribution of As(V), Cd, Cr(III), Hg(II), and methylmercury (MeHg) in killifish (Fundulus heteroclitus) following aqueous exposure in water collected from 3 contaminated field sites-Baltimore Harbor and Elizabeth River (Chesapeake Bay), and Mare Island (San Francisco Bay)-using a radiotracer technique. Uptake rate constants (L?g-1?d-1) were highest for MeHg (0.370-0.781) and lowest for As (0.00028-0.00065). Loss rate constants (d-1) were highest for As (0.046-0.096) and lowest for MeHg (0.006-0.009). Tissue distribution data showed that MeHg was redistributed around the body throughout the 9-d depuration period, and drinking may be an uptake mechanism for Cd from the aqueous phase in higher-salinity water. The kinetic parameters calculated in the present study were entered into a bioaccumulation model to calculate the predicted body burden of each metal at steady state and the percentage body burden attributable to dietary exposure on a site-specific basis. Calculated body burdens varied between field sites for all metals except Cr. The predicted values for Cd, Hg(II), and MeHg matched independent field data from contaminated estuaries, indicating that the model can account for the major processes governing metal concentration in killifish. The diet accounted for &gt;97% of the body burden of Cd and MeHg and was the predominant exposure route for As and Cr.",
Arsenic,1936159,Process Optimization for Arsenic Adsorption onto Natural Zeolite Incorporating Metal Oxides by Response Surface Methodology Abstract: ,
Arsenic,1797751,Arsenical association: inorganic arsenic may accumulate in the meat of treated chickens Abstract: ,
Arsenic,1344476,"Differential accumulation of U14 snoRNA and hsc70 mRNA in Chinese hamster cells after exposure to various stress conditions Abstract: We have previously characterized the unique organization of the U14 small nucleolar ribonucleic acid (snoRNA) gene in Chinese hamster HA-1 cells. The single copy of the hsc70/U14 gene is the only source for the production of both U14 snoRNA species and hsc70 messenger ribonucleic acid (mRNA) in these cells. Here we report that the accumulations of U14 snoRNA and hsc70 mRNA are different in response to various stress conditions, although both of them are transcribed in a single primary transcript. Heat shock induced an increased accumulation of both U14 snoRNA and hsc70 mRNA. On the other hand, exposure to sodium arsenite or azetidine induced an increased accumulation of hsc70 mRNA, but did not lead to a concomitant increase in the level of U14 snoRNA. Under normal growth conditions, the variations in the levels of U14 snoRNA and hsc70 mRNA, in the different phases of the cell cycle, are correlated. The increased expression of U14 snoRNA and hsc70 mRNA, and the hsc70 protein induced specifically by heat shock suggest that they participate in the repair process of heat-induced damage to macromolecular complexes involved in the synthesis and processing of ribosomal RNA.",
Arsenic,1337555,"Dihydroxy-isosteviol-methyl-ester, an active biological component of Pulsatilla nigricans, reduces arsenic induced cellular dysfunction in testis of male mice Abstract: Arsenic contamination has become a menacing health concern, warranting search for new drugs capable of ameliorating its toxicity. Extract of Pulsatilla nigricans is occasionally used as traditional medicine including homeopathy to combat/alleviate toxicity-related symptoms of known or unknown cause. Mice were intoxicated with a sub-lethal dose of sodium arsenite (20mg/kg b.w./day, determined through a range-finding trial) and the effect on testicular toxicity after 30, 60, and 90 days was examined. We observed an increased level of reactive oxygen species, cellular damage in testes of SA-intoxicated mice and further analysed expressions of apoptotic signal proteins and mRNA like Bax, Bcl2 and caspase3. Treatment with EEPN showed significant inhibition/reversal of the arsenic-induced toxic effect in testis and reduced oxidative stress through modulating expressions of signal proteins, thereby inhibiting the progression of events of apoptosis in testis cells and sperm. Therefore, EEPN has potentials for therapeutic use in arsenic- induced reproductive toxicity.",
Arsenic,1332250,"Metallothionein-II and ferritin H mRNA levels are increased in arsenite-exposed HeLa cells Abstract: Arsenite is extremely toxic and, though non-mutagenic, is a carcinogen. To determine the effects of arsenite on changes in cell physiology, we searched for genes in HeLa cells whose mRNAs are more abundant after cellular exposure to arsenite. A cDNA subtraction was performed between cDNA synthesized from HeLa cells grown in the absence and presence of 5 microM sodium arsenite. Isolation and sequencing of three clones that showed a higher hybridization signal to RNA from arsenite-exposed cells, versus unexposed cells, revealed that two of the cDNAs coded for human ferritin H chain and the other coded for metallothionein-II. These results suggest the possibility that arsenite exposure may lead to increased levels of oxygen radicals, which augmented metallothionein and ferritin can act to detoxify.",
Arsenic,1340138,"Environmental risks of trace elements associated with long-term phosphate fertilizers applications: a review Abstract: Application of phosphate fertilizer can be a significant contributor of potentially hazardous trace elements such as arsenic, cadmium, and lead in croplands. These trace elements have the potential to accumulate in soils and be transferred through the food chain. We articulated the environmental risks of trace elements associated with long-term phosphate fertilizer applications by combining data from the literature and results from model simulations. Results illustrate that under normal cropping practice, the impact of phosphate fertilizers applications on trace element accumulation in receiving soils has been limited and localized. Their plant uptake varied greatly depending on the fertilizer application rates, soil and plant characteristics. This has led to a great deal of uncertainty in characterizing soil distribution coefficients, Kd, and plant uptake factors, PUF, two of the most used parameters in assessing the risks of accumulations. Therefore, the risks may be more appropriately assessed based on the probabilistic distributions of Kd and PUF.",
Arsenic,627062,"Kinetics of arsenic methylation by freshly isolated B6C3F1 mouse hepatocytes Abstract: The toxic and carcinogenic effects of arsenic may be mediated by both inorganic and methylated arsenic species. The methylation of arsenic(III) is thought to take place via sequential oxidative methylation and reduction steps to form monomethylarsenic (MMA) and dimethylarsenic (DMA) species, but recent evidence indicates that glutathione complexes of arsenic(III) can be methylated without oxidation. The kinetics of arsenic methylation were determined in freshly isolated hepatocytes from male B6C3F1 mice. Hepatocytes (&gt;90% viability) were isolated by collagenase perfusion and suspended in Williams' Medium E with various concentrations of arsenic(III) (sodium m-arsenite). Aliquots of the lysed cell suspension were analyzed for arsenic species by hydride generation-atomic absorption spectrometry. The formation of MMA(III) from sodium arsenite (1 microM) was linear with respect to time for &gt;90 min. DMA(III) formation did not become significant until 60 min. MMA(V) and DMA(V) were not consistently observed in the incubations. These results suggest that the glutathione complex mechanism of methylation plays an important role in arsenic biotransformation in mouse hepatocytes. Metabolism of arsenic(V) was not observed in mouse hepatocytes, consistent with inhibition of arsenic(V) active cellular uptake by phosphate in the medium. The formation of MMA(III) increased with increasing arsenic(III) concentrations up to approximately 2 microM and declined thereafter. The concentration dependence is consistent with a saturable methylation reaction accompanied by uncompetitive substrate inhibition of the reaction by arsenic(III). Kinetic analysis of the data suggested an apparent K(M) of approximately 3.6 microM arsenic(III), an apparent V(max) of approximately 38.9 microg MMA(III) formed/L/h/million cells, and an apparent K(I) of approximately 1.3 microM arsenic(III). The results of this study can be used in the physiologically based pharmacokinetic model for arsenic disposition in mice to predict the concentration of MMA(III) in liver and other tissues.",
Arsenic,1033358,"A cohort study on mortality among long-time employed Swedish chimney sweeps Abstract: A cohort study on mortality among all members of the Swedish Chimney Sweeps Union who were active in 1950 or later and have been members for at least 10 a has been performed; 2,071 chimney sweeps fulfilled the criteria and the loss in the follow-up was less than 1 %. The observed numbers of death before the age of 80 were compared with sex-, calendar year-, and age class specific expectancy values from the national statistics of 1951-1979. Two hundred and thirty deaths were observed versus 197.6 expected. This result was due to a significant excess of deaths from tumors, particularly lung and esophageal cancer, and from nonmalignant chronic respiratory diseases. The multifold increased risk from these diseases could hardly be explained by extreme smoking or alcohol habits but rather by exposure to polycyclic aromatic hydrocarbons, nitrogen compounds, arsenic, and asbestos in combination with exposure to sulfur dioxide. The excess mortality had occurred in spite of favorable selection factors as demonstrated in different subcohorts. Preventive actions to diminish inhalation of soot and combustion gases should be taken.",
Arsenic,2347738,"Structural basis for arsenate-phosphate discrimination Abstract: In Nature arsenate can in principle replace phosphate in its role as a key biological molecule (e.g. as in ATP) but arsenate analogues are less stable with respect to hydrolysis and reduction. Yet bacterial adoption of arsenic has been described and although the precise nature of the arsenic species is undetermined, it is possible that arsenate is incorporated as direct substitution for phosphate in cellular macromolecules. Several phosphate-binding proteins are able to selectively bind phosphate over arsenate despite their chemical similarities.",
Arsenic,1351250,Sorption Behavior of Arsenate by Mg-Bearing Minerals at Hyperalkaline Condition: Implications for Oxyanions Sequestration During the Use and Disposal of Alkaline Wastes Abstract: ,
Arsenic,1250973,"Arsenic speciation in polychaetes (Annelida) and sediments from the intertidal mudflat of Sundarban mangrove wetland, India Abstract: This paper documents the concentration of total arsenic and individual arsenic species in four soft-bottom benthic polychaetes (Perenereis cultifera, Ganganereis sootai, Lumbrinereis notocirrata and Dendronereis arborifera) along with host sediments from Sundarban mangrove wetland, India. An additional six sites were considered exclusively for surface sediments for this purpose. Polychaetes were collected along with the host sediments and measured for their total arsenic content using inductively coupled plasma mass spectrometry. Arsenic concentrations in polychaete body tissues varied greatly, suggesting species-specific characteristics and inherent peculiarities in arsenic metabolism. Arsenic was generally present in polychaetes as arsenate (As(V) ranges from 0.16 to 0.50 mg kg(-1)) or arsenite (As(III) ranges from 0.10 to 0.41 mg kg(-1)) (30-53 % as inorganic As) and dimethylarsinic acid (DMA(V) &lt;1-25 %). Arsenobetaine (AB &lt; 16 %), and PO(4)-arsenoriboside (8-48 %) were also detected as minor constituents, whilst monomethylarsonic acid (MA(V)) was not detected in any of the polychaetes. The highest total As (14.7 mg kg(-1) dry wt) was observed in the polychaete D. arborifera collected from the vicinity of a sewage outfall in which the majority of As was present as an uncharacterised compound (10.3 mg kg(-1) dry wt) eluted prior to AB. Host sediments ranged from 2.5 to 10.4 mg kg(-1) of total As. This work supports the importance of speciation analysis of As, because of the ubiquitous occurrence of this metalloid in the environment, and its variable toxicity depending on chemical form. It is also the first work to report the composition of As species in polychaetes from the Indian Sundarban wetlands.",
Arsenic,1677685,"Predisposing factors of hepatocellular carcinoma recurrence following complete remission in response to transarterial chemoembolization Abstract: <strong>BACKGROUND AND AIM: </strong>The aim of our study was to determine the predictors of recurrences in hepatocellular carcinoma (HCC) patients who had achieved complete remission (CR) by transarterial chemoembolization (TACE).<br /><br /><strong>METHODS: </strong>A total of 220 consecutive HCC patients who had achieved CR by TACE were followed for a median 72 months. CR was defined as complete lipiodol uptake based on the results of lipiodol-computed tomography 4 weeks after TACE and no additional tumor staining on the follow-up angiography. Recurrence patterns were classified as local recurrence and secondary tumor, respectively, in relation to the location of recurrence; early and late recurrence were classified in relation to recurrence time.<br /><br /><strong>RESULTS: </strong>Recurrence of HCC was observed in 169 patients (77 %), of whom 91 (54 %) had local recurrences, 61 (36 %) had secondary tumor, and 17 (10 %) had both. There were 45 (27 %) early and 124 (73 %) late recurrences. Local recurrence developed more frequently in patients with early recurrence than in those with late recurrence (62 vs. 51 %, respectively), while secondary tumor was detected more commonly in patients with late recurrence than in those with early recurrence (39 vs. 29 %, respectively; P &lt; 0.001). In multivariate analyses, multinodularity [hazard ratio (HR) 2.351, P = 0.023] and a persistently high serum alpha-fetoprotein level following CR (HR 3.173, P &lt; 0.001) were significant predictors of early recurrence. Older age (?60 years; HR 1.531, P = 0.043), advanced Child-Pugh class (HR 1.983, P = 0.002), and the association with cirrhosis (HR 1.756, P = 0.028) were predictors of late recurrence following CR.<br /><br /><strong>CONCLUSIONS: </strong>Early recurrences following CR by TACE may be due mainly to undetectable remaining tumors, whereas late recurrences may be caused by newly appearing tumors in patients with a background of advanced cirrhotic liver.",
Arsenic,1351148,NEW INSTRUMENTAL SYSTEMS IN ATOMIC-ABSORPTION SPECTROSCOPY APPLIED TO TOXIC ELEMENTS ANALYSIS - DETERMINATION OF ARSENIC WITH MORE ADVANCED SAMPLING SYSTEMS Abstract: ,
Arsenic,1340265,"The crystal and molecular-structure of fac, fac-Mo2(CO)6(Ph2AsCH2CH2PPh2)3 a case of chemically imposed disorder in the crystal-structure Abstract: Crystals of fac,fac-Mo2(CO)6(ape)3 (ape = Ph2AsCH2CH2PPh2) are monoclinic, P 21/n (No. 14), a 15.842(4), b 17.178(4), c 14.144(4) Å, ? 98.80(3)º. The compound is dimeric with a bridging ape group, and the stereochemical arrangement of the carbonyl groups about each metal atom is facial. The facial arrangement leads to a chemically imposed disorder among the ape ligand donor atoms; this makes it impossible to distinguish arsenic and phosphorus atoms in the crystal structure determination.",
Arsenic,1033695,"Methylations of 70,000-Da heat shock proteins in 3T3 cells: alterations by arsenite treatment, by different stages of growth and by virus transformation Abstract: We have characterized the basic amino acid methylation of three members of the 70,000-Da heat shock protein superfamily, hsp68, hsc70, and BiP, in Balb/c 3T3 cells. It appears that a lysyl residue is the only methylation site in BiP and that both lysyl and arginyl residues are methylated in hsp68 and hsc70. In all cases, epsilon-N-trimethyllysine is the predominant methyllysine species. Both NG-monomethylarginine and NG,NG-dimethylarginine are identified as the methylarginine species. The stoichiometry of the methylation is indirectly determined by using the amount of actin methylation as a reference. Three, four, and four methyl groups are incorporated into lysyl residues of hsp68, hsc70, and BiP, respectively. The level of lysyl methylation in hsc70 remains unchanged under different growth conditions. On the other hand, the arginyl methylation in hsc70 varies considerably. In confluent Balb/c 3T3 cells, there are 1.8 and 1.3 methyl groups in dimethylarginine and monomethyl-arginine, respectively. In nonconfluent cells, the amount of monomethylarginine is similar to that in confluent cells, but dimethylarginine is not detectable. Furthermore, in both confluent and nonconfluent cells, the level of monomethylarginine is reduced 5- to 10-fold after arsenite treatment. However, in 3T3 cells transformed by Rous sarcoma virus (SR-RSV 3T3 cells), the level of arginine methylation is constitutively lower and cannot be reduced further by arsenite.",
Arsenic,1027571,"Taurine prevents arsenic-induced cardiac oxidative stress and apoptotic damage: role of NF-kappa B, p38 and JNK MAPK pathway Abstract: Cardiac dysfunction is a major cause of morbidity and mortality worldwide due to its complex pathogenesis. However, little is known about the mechanism of arsenic-induced cardiac abnormalities and the use of antioxidants as the possible protective agents in this pathophysiology. Conditionally essential amino acid, taurine, accounts for 25% to 50% of the amino acid pool in myocardium and possesses antioxidant properties. The present study has, therefore, been carried out to investigate the underlying mechanism of the beneficial role of taurine in arsenic-induced cardiac oxidative damage and cell death. Arsenic reduced cardiomyocyte viability, increased reactive oxygen species (ROS) production and intracellular calcium overload, and induced apoptotic cell death by mitochondrial dependent caspase-3 activation and poly-ADP ribose polymerase (PARP) cleavage. These changes due to arsenic exposure were found to be associated with increased IKK and NF-kappaB (p65) phosphorylation. Pre-exposure of myocytes to an IKK inhibitor (PS-1145) prevented As-induced caspase-3 and PARP cleavage. Arsenic also markedly increased the activity of p38 and JNK MAPKs, but not ERK to that extent. Pre-treatment with SP600125 (JNK inhibitor) and SB203580 (p38 MAPK inhibitor) attenuated NF-kappaB and IKK phosphorylation indicating that p38 and JNK MAPKs are mainly involved in arsenic-induced NF-kappaB activation. Taurine treatment suppressed these apoptotic actions, suggesting that its protective role in arsenic-induced cardiomyocyte apoptosis is mediated by attenuation of p38 and JNK MAPK signaling pathways. Similarly, arsenic intoxication altered a number of biomarkers related to cardiac oxidative stress and other apoptotic indices in vivo and taurine supplementation could reduce it. Results suggest that taurine prevented arsenic-induced myocardial pathophysiology, attenuated NF-kappaB activation via IKK, p38 and JNK MAPK signaling pathways and could possibly provide a protection against As-induced cardiovascular burden.",
Arsenic,1022046,"The fate of arsenic in soil-plant systems Abstract: Arsenic is a natural trace element found in the environment. In some cases and places, human activities have increased the soil concentration of As to levels that exceed hazard thresholds. Amongst the main contributing sources of As contamination of soil and water are the following: geologic origin, pyriticmining, agriculture, and coal burning. Arsenic speciation in soils occurs and is relatively complex. Soils contain both organic and inorganic arsenic species. Inorganic As species include arsenite and arsenate, which are the most abundant forms found in the environment. The majority of As in aerated soils exists as H?AsO?- (acid soils) or HAsO?²- (neutral species and basic). However, HA?sO? is the predomiant anaerobic soils, where arsenic availability is higher and As(III) is more weakly retained in the soil matrix than is As(V). The availability of As in soils is usually driven by multiple factors. Among these factors is the presence of Fe-oxides and/or phosphorus, (co)precipitation in salts, pH, organic matter, clay content, rainfall amount, etc. The available and most labile As fraction can potentially be taken up by plant roots, although the concentration of this fraction is usually low. Arsenic has no known biological function in plants. Once inside root cells, As(V) is quickly reduced to As(III), and, in many plant species, becomes complexed. Phosphorus nutrition influences As(V) uptake and toxicity in plants, whilst silicon has similar influences on As(III). Plants cope with As contamination in their tissues by possessing detoxification mechanisms. Such mechanisms include complexation and compartmentalization. However, once these mechanisms are saturated, symptoms of phytotoxicity appear. Phytotoxic effects commonly observed from As exposure includes growth inhibition, chlorophyll degradation, nutrient depletion and oxidative stress. Plants vary in their ability to accumulate and tolerate As (from tolerant hyperaccumulators to sensitive excluders), and some plants are useful for soil reclamation and in sustainable agriculture, The status of current scientific knowledge allows us to manage As contamination in the soil-plant system and to mitigate arsenic's effects. Phytoremediation is an emerging technology suitable for reclaiming As-contaminated soils and waters. Phytoextraction has been used to clean As-contaminated soils, although its applicability has not yet reached maturity. Phytostabilization has been employed to reduce environmental risk by confining As as an inert form in soils and has shown success in both laboratory experiments and in field trials. Phytofiltration has been used to treat As-enriched waters. Such treatment removes As when it is accumulated in plants grown in or on water. In agricultural food production, appropriate soil management and plant variety/species selection can minimize As-associated human dis- eases and the transfer of As within the food chain. Selecting suitable plants for use on As-contaminated soils may also enhance alternative land use, such as for energy or raw material production.",
Arsenic,1519028,"Arsenic sorption by nanocrystalline magnetite: An example of environmentally promising interface with geosphere Abstract: In this paper, the sorption of arsenic onto nanocrystalline magnetite mineral Fe3O4 was studied in a model system. Nanocrystalline magnetite was produced by mechanical activation in a planetary ball mill from natural microcrystalline magnetite. As a consequence of milling, the specific surface area increased from 0.1 m2/g to 11.9 m2/g and the surface site concentration enhanced from 2.2 sites/nm2 to 8.4 sites/nm2. These changes in surface properties of magnetite lead to the enhancement of arsenic removal from model system. The best sorption ability was achieved with magnetite sample activated for 90 min. In this case the sample was able to absorb around 4 mg/g. The structural changes of magnetite were also observed and the new hematite phase was detected after 120 min of milling. A good correlation between the decreasing particle size, increasing specific surface area and reduction of saturation magnetization was found. In desorption study, KOH and NaOH were found as the best eluents where more than 70% of arsenic was released back into the solution. The principal novelty of the paper is that mineral magnetite, truly one nature's gift can be used after smart milling (mechanical activation) as an effective arsenic sorbent.",
Arsenic,583064,"Preventive mechanism of cellular glutathione in monomethylarsonic acid-induced cytolethality Abstract: Human pentavalent arsenic metabolic intermediate, monomethylarsonic acid (MMAsV), is a major arsenic type found in the blood in chronic arsenic poisoning patients, but little information is available on its toxicity potential or mechanisms of action. In this study, we investigated the molecular mechanisms of in vitro cytolethality of MMAsV using rat liver TRL 1215 cells. Cellular arsenic concentrations reached the nanomolar range in TRL 1215 cells when cells were exposed to millimolar levels of MMAsV, and most of the MMAsV was not metabolized during the 48-h incubation. Under these conditions, MMAsV showed significant cytolethality when cellular reserves of reduced glutathione (GSH) were depleted. Morphological and biochemical evidence confirmed that MMAsV induced both necrosis and apoptosis in the cellular GSH-depleted cells. MMAsV significantly enhanced cellular caspase 3 activity in the cellular GSH-depleted cells, and a caspase 3 inhibitor blocked MMAsV-induced apoptosis. MMAsV also enhanced the production of cellular reactive oxygen species (ROS) in the cellular GSH-depleted cells, and addition of a membrane-permeable radical trapping reagent completely prevented both MMAsV-induced cellular caspase 3 activation and cytolethality in these cells. These observations suggest that MMAsV typically generates harmful ROS in cells, and cellular GSH prevents cytolethality by scavenging these toxic ROS. However, when cellular GSH levels are decreased, MMAsV induces oxidative stress in the cells, and this leads to apoptosis and/or necrosis depending on the cellular ROS/GSH ratio.",
Arsenic,1579377,A review of the arsenic concentration in paddy rice from the perspective of geoscience Abstract: ,
Arsenic,1936102,"High intensity magnetic separation for the clean-up of a site polluted by lead metallurgy Abstract: The industrial history in the district of Linares (Spain) has had a severe impact on soil quality. Here we examined soil contaminated by lead and other heavy metals in &quot;La Cruz&quot; site, a brownfield affected by metallurgical residues. Initially, the presence of contaminants mainly associated with the presence of lead slag fragments mixed with the soil was evaluated. The subsequent analysis showed a quasi-uniform distribution of the pollution irrespective of the grain-size fractions. This study was accompanied by a characterization of the lead slag behavior under the presence of a magnetic field. Two main magnetic components were detected: first a ferromagnetic and/or ferrimagnetic contribution, second a paramagnetic and/or antiferromagnetic one. It was also established that the slag was composed mainly of lead spherules and iron oxides embedded in a silicate matrix. Under these conditions, the capacity of magnetic separation to remove pollutants was examined. Therefore, two high intensity magnetic separators (dry and wet devices, respectively) were used. Dry separation proved to be successful at decontaminating soil in the first stages of a soil washing plant. In contrast, wet separation was found effective as a post-process for the finer fractions.",
Arsenic,2278513,"Arsenic retention in foliage and soil after monosodium methyl arsenate (MSMA) application to turfgrass Abstract: Monosodium methyl arsenate (MSMA) is a commonly used herbicide for weed control in turfgrass systems. There is concern that arsenic from applied MSMA could leach to groundwater or run off into surface water, thereby threatening human and ecosystem health. The USEPA has proposed a phase-out of the herbicide but is seeking additional research about the toxicity and environmental impacts of MSMA before establishing a final ruling. Little research has systematically investigated MSMA in field-based settings; instead, risks have been inferred from isolated field measurements or model-system studies. Accordingly, the overall goal of this study was to quantify the fate of arsenic after MSMA application to a managed turfgrass system. After MSMA application to turfgrass-covered and bareground lysimeters, the majority of arsenic was retained in turfgrass foliage and soils throughout year-long experiments, with 50 to 101% of the applied arsenic recovered in turfgrass systems and 55 to 66% recovered in bareground systems. Dissolved arsenic concentrations from 76.2-cm-depth pore water in the MSMA-treated soils were consistently <2 ?g L?1, indistinguishable from background concentrations. As measured by adsorption isotherm experiments, MSMA retention by the sandy soil from our field site was markedly less than retention by a washed sand and a clay loam. Collectively, these results suggest that under aerobic conditions, minimal arsenic leaching to groundwater would occur after a typical application of MSMA to turfgrass. However, repeated MSMA application may pose environmental risks. Additional work is needed to examine arsenic cycling near the soil surface and to define arsenic speciation changes under different soil conditions.",
Arsenic,2088374,"Acute and subchronic toxicity study of Tamra bhasma (incinerated copper) prepared from Ashodhita (unpurified) and Shodhita (purified) tamra in rats Abstract: The use of metals in traditional medicines is very often seen as matter of concern these days, especially the Bhasma preparations which are always under stringent observations for containing highly reactive inorganic elements such as lead, mercury, arsenic and others. One of the Bhasma extensively used in routine Ayurvedic practice is Tamra (copper) bhasma. If it is not prepared properly or Shodhana procedure is not done properly, it acts as a poison. To indicate its toxic potential, Ashtamahadoshas (eight major ill effects) have been quoted in classics and due emphasis have been given to its Shodhana procedure. In the present study, Tamra bhasma prepared from Shodhita and Ashodhita Tamra was subjected to oral toxicity study to ascertain the role of Shodhana process on safety profile of Tamra bhasma on subchronic administration to albino rats. Both the samples were administered to rats for 45 consecutive days at the doses of 5.5, 27.5, and 55 mg/kg. Animals were sacrificed on 46(th) day and parameters like hematological, serum biochemical, and histopathology of various organs were studied. Results showed that Tamra bhasma prepared from Ashodhita Tamra has pathological implications on different hematological, serum biochemical and cytoarchitecture of different organs even at therapeutic dose level (5.5 mg/kg). Whereas, Tamra bhasma prepared from Shodhita Tamra is safe even at five-fold to therapeutic equivalent doses (27.5 mg/kg). These observations emphasize the role of Shodhana and importance of dose in expression of toxicity of the medicinal preparations.",
Arsenic,735097,"Variations in arsenic methylation capacity and oxidative DNA lesions over a 2-year period in a high arsenic-exposed population Abstract: OBJECTIVE: To assess long-term variations in arsenic methylation and oxidative DNA lesions of chronic high arsenic-exposed populations. METHODS: A follow-up study was conducted in 64 chronic high arsenic-exposed subjects from 2004 to 2006. Urinary arsenic species and 8-hydroxydeoxyguanine were measured. RESULTS: Percentages of urinary inorganic arsenic, monomethylarsonate and urinary 8-hydroxydeoxyguanine (8-OHdG) level were significantly higher, but the percentage of dimethylarsinate, the primary methylation index (PMI) and secondary methylation index (SMI) was lower in the ninth year of arsenic exposure compared with the seventh year. Substantial differences in relative arsenic methylation capacity were observed between the seventh and ninth year. Percentages of arsenic species, PMI and SMI were significantly correlated between siblings, and between parents and children. CONCLUSIONS: Arsenic methylation may decrease, but oxidative DNA lesions may increase with the increase of cumulative arsenic exposure level. Both genetic and environmental factors may contribute to variability in arsenic methylation.",
Arsenic,1579263,"Detection of arsenic-containing hydrocarbons in a range of commercial fish oils by GC-ICPMS analysis Abstract: The present study describes the use of a simple solid-phase extraction procedure for the extraction of arsenic-containing hydrocarbons from fish oil followed by analysis using gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICPMS). The procedure permitted the analysis of a small sample amount, and the method was applied on a range of different commercial fish oils, including oils of anchovy (Engraulis ringens), Atlantic herring (Clupea harengus), sand eel (Ammodytes marinus), blue whiting (Micromesistius poutassou) and a commercial mixed fish oil (mix of oils of Atlantic herring, Atlantic cod (Gadus morhua) and saithe (Pollachius virens)). Total arsenic concentrations in the fish oils and in the extracts of the fish oils were determined by microwave-assisted acid digestion and ICPMS. The arsenic concentrations in the fish oils ranged from 5.9 to 8.7 mg kg(-1). Three dominant arsenic-containing hydrocarbons in addition to one minor unidentified compound were detected in all the oils using GC-ICPMS. The molecular structures of the arsenic-containing hydrocarbons, dimethylarsinoyl hydrocarbons (C17H38AsO, C19H42AsO, C23H38AsO), were verified using GC coupled to tandem mass spectrometry (MS/MS), and the accurate masses of the compounds were verified using quadrupole time-of-flight mass spectrometry (qTOF-MS). Additionally, total arsenic and the arsenic-containing hydrocarbons were studied in decontaminated and in non-decontaminated fish oils, where a reduced arsenic concentration was seen in the decontaminated fish oils. This provided an insight to how a decontamination procedure originally ascribed for the removal of persistent organic pollutants affects the level of arsenolipids present in fish oils.",
Arsenic,1247626,"A case-control study on occupational risk factors for sino-nasal cancer Abstract: <strong>OBJECTIVES: </strong>Sino-nasal cancer has been consistently associated with exposure to wood dust, leather dust, nickel and chromium compounds; for other occupational hazards, the findings are somewhat mixed. The aim of this study was to investigate the risk of sino-nasal epithelial cancer (SNEC) by histological type with prior exposure to suspected occupational risk factors and, in particular, those in metalworking.<br /><br /><strong>METHODS: </strong>Between 1996 and 2000, incident cases were collected on a monthly basis from hospitals throughout the Piedmont region of Italy by the regional Sino-nasal Cancer Registry. A questionnaire on occupational history, completed by 113 cases and 336 hospital controls, was used to assign exposure to occupational hazards. The relationship between SNEC and cumulative exposure to these hazards was explored using unconditional logistic regression to statistically adjust for age, sex, smoking and co-exposures, allowing for a 10-year latency period.<br /><br /><strong>RESULTS: </strong>The risk of adenocarcinoma was significantly increased with ever-exposure to wood dust (odds ratio; OR = 58.6), and to leather dust (OR = 32.8) and organic solvents (OR = 4.3) after controlling for wood dust, whereas ever-exposure to welding fumes (OR = 3.7) and arsenic (OR = 4.4) significantly increased the risk for squamous cell carcinoma. For each of these hazards, a significant increasing trend in risk across ordered cumulative exposure categories was found and, except for arsenic, a significantly increased risk with ever-exposure at low intensity. Treating cumulative exposure on a continuous scale, a significant effect of textile dusts was also observed for adenocarcinoma. For a mixed group of other histological types, a significant association was found with wood dust and organic solvents.<br /><br /><strong>CONCLUSIONS: </strong>Some occupational risk factors for SNEC were confirmed, and dose-response relationships were observed for other hazards that merit further investigation. The high risk for adenocarcinoma with low-intensity exposure to wood dust lends support for a reduction in the occupational threshold value.",
Arsenic,1025505,"Arsenic resistant bacteria isolated from arsenic contaminated river in the Atacama Desert (Chile) Abstract: In this study, arsenic resistant bacteria were isolated from sediments of an arsenic contaminated river. Arsenic tolerance of bacteria isolated was carried out by serial dilution on agar plate. Redox abilities were investigated using KMnO4. arsC and aox genes were detected by PCR and RT-PCR, respectively. Bacterial populations were identified by RapID system. Forty nine bacterial strains were isolated, of these, 55 % corresponded to the reducing bacteria, 4% to oxidizing bacteria, 8% presented both activities and in 33% of the bacteria none activity was detected. arsC gene was detected in 11 strains and aox genes were not detected. The activity of arsenic transforming microorganisms in river sediment has significant implications for the behavior of the metalloid.",
Arsenic,406093,"Reversal of arsenic-induced hepatic apoptosis with combined administration of DMSA and its analogues in guinea pigs: role of glutathione and linked enzymes Abstract: Arsenicosis, due to contaminated drinking water in the Indo-Bangladesh region, is a serious health hazard in terms of morbidity and mortality. Reactive oxygen species (ROS) generated due to arsenic toxicity have been attributed as one of the initial signals that impart cellular toxicity, which is controlled by the internal antioxidant glutathione (GSH). In the present study, we investigated (i) the role of GSH and its linked enzymes, glutathione peroxidase and glutathione reductase, in reversing chronic arsenic toxicity using a thiol chelating agent, meso-2,3-dimercaptosuccinic acid (DMSA), or one of its analogues individually or in combination; (ii) if alterations in the carbon side chain of DMSA increased efficacy; and (iii) whether the combination therapy enhance arsenic removal from hepatic tissue and prevent hepatic apoptosis. Results indicated that chronic arsenic exposure led to a ROS-mediated, mitochondrial-driven, caspase-dependent apoptosis in hepatic cells with a significant increase in glutathione disulfide (GSSG) levels and decreased glutathione reductase levels. Monotherapy with DMSA and its analogues did show minimal recovery postchelation. However, the combination of DMSA with long carbon chain analogues like monoisoamyl DMSA (MiADMSA) or monocyclohexyl DMSA (MchDMSA) showed a better efficacy in terms of reducing the arsenic burden as well as reversing altered biochemical variables indicative of oxidative stress and apoptosis. We also observed that GSH and its linked enzymes, especially glutathione reductase, play a vital role in scavenging ROS, maintaining GSH pools, and providing clinical recoveries. On the basis of the above observations, we recommend that combinational therapy of DMSA and its long carbon chain analogues MiADMSA or MchDMSA would be more effective in arsenic toxicity.",
Arsenic,1346703,"Multiple basic-leucine zipper proteins regulate induction of the mouse heme oxygenase-1 gene by arsenite Abstract: The mechanism of heme oxygenase-1 (ho-1) gene activation by arsenite was examined. Arsenite-stimulated expression of a ho-1 promoter/luciferase chimera in a dose-dependent manner in mouse hepatoma (Hepa) cells. Mutation analyses identified the arsenite-responsive sequence as the stress-response element (StRE), which resembles the binding sites for the AP-1 superfamily of basic-leucine zipper factors. In electrophoretic mobility shift assays, up to seven specific StRE-protein complexes were routinely detected using extracts from untreated Hepa cells whereas a single complex was typically observed after treatment with arsenite. Antibody &quot;supershift&quot; experiments identified Nrf2, JunD, and ATF3 in control complexes and the amount of these factors increased significantly in the arsenite-induced complex. MafG, ATF2, FosB, and JunB were also detected in the arsenite complex. Activation of a StRE-dependent luciferase gene by arsenite was inhibited to varying degrees by dominant-negative mutants of Nrf2, MafK, c-Fos, and CREB but most strongly with the latter. Together, these results implicate multiple basic-leucine zipper transcription factors in ho-1 gene activation by arsenite.",
Arsenic,2337133,"Galvanic replacement of As(0) nanoparticles by Au(III) for nanogold fabrication and SERS application Abstract: A galvanic replacement reaction between As(0) nanoparticles and Au(III) ions has been reported for the first time. Initially the stable yellow-brown As(0) nanoparticles were prepared by the borohydride reduction of an arsenite solution. The characterization of the As(0) particles was discussed in a recent report. In the present work these As(0) nanoparticles were exploited to fabricate gold nanoparticles (AuNPs). The as-obtained red colored gold sol showed a lambda(max) at 540 nm and the size of the AuNPs were 62 +/- 7 nm as observed from TEM analyses. It was interesting to note that the size of the AuNPs was comparable to that of the As(0) nanoparticles, which could be a sign of galvanic replacement in the absence of any stabilizer. The particles were spherical with a hollow core. The AuNPs were characterized by SEM, TEM, XRD, DLS and UV-visible spectroscopy. FTIR and Raman analysis indicated that during the galvanic replacement reaction As(0) was oxidized to arsenate, which stabilized the AuNPs through adsorption and H-bonding. Thus a stable assembly of AuNPs was obtained in the absence of any external stabilizer. The potential of such an assembly was further exploited for SERS detection of Rhodamine 6G, 4-mercaptopyridine and 4-aminothiophenol.",
Arsenic,1019928,"Association between the clastogenic effect in peripheral lymphocytes and human exposure to arsenic through drinking water Abstract: We describe the association between structural chromosome aberrations (CAs) and parameters of exposure to arsenic among 42 individuals exposed to arsenic through well waters in Finland. The median concentration of arsenic in the wells was 410 microg/l, the total arsenic concentrations in urine (As-tot) was 180 microg/l, and in hair 1.3 microg/g, for current users (n = 32) of contaminated wells. Urinary arsenic species and CAs were also analyzed in eight control individuals from the same village who consumed water which contained arsenic &lt;1.0 microg/l (detection limit). Increased arsenic exposure, indicated best by increased concentrations of arsenic species (inorganic arsenic, methylarsonic acid (MMA), dimethylarsinic acid (DMA)) in urine, was associated with increased frequency of CAs. The increased urinary ratio of MMA/As-tot and the decreased ratio of DMA/As-tot were associated with increased CAs when all aberration types, including gaps, were considered. Associations between CAs and arsenic exposure indicators were stronger among current users than among persons who had stopped using the contaminated well water for 2-4 months before sampling (ex-users, n = 10). Furthermore, there was a positive but not statistically significant association between CAs and arsenic in hair among the current users, but not among the ex-users, who still had relatively high arsenic concentrations in hair. The results suggest that the effect observed in the present study reflects relatively recent arsenic exposure.",
Arsenic,2149135,"Assessing Arsenic Exposure from Consumption of Seafood from Vieques-Puerto Rico: A Pilot Biomonitoring Study Using Different Biomarkers Abstract: The various toxic effects associated with inorganic arsenic (iAs) warrants that exposure sources be identified. This pilot study evaluated if greater seafood consumption from Vieques-Puerto Rico is associated with increased exposure to iAs. Nail, hair, and urine samples were used as biomarkers of iAs exposure in adult women and men from Vieques classified as high (n = 31) and low (n = 21) seafood consumers, who reported eating fish and/or shellfish ?1 time per week and once per month or less, respectively. The sum of urinary iAs (As III + As V), monomethylarsonic acid (MA[V]), and dimethylarsinic acid (DMA[V]), denoted as SumAs, fluctuated from 3.3 µg/g Cr (1.2 ?g/L) to 42.7 ?g/g Cr (42 ?g/L) (n = 52). Levels of As in nail samples (n = 49) varied from 0.04 to 0.82 ?g/g dry weight (dw), whereas in hair (n = 49) As was only detected in 49 % of the samples with a maximum value of 0.95 ?g/g dw. None of the biomarkers of exposure to As exceeded exposure reference values for urine (50 ?g/g Cr or 50 ?g/L), nails (1 ?g/g), or hair (1 ?g/g). However, median (10.0 ?g/g Cr; 10.6 ?g/L) and 95th percentile (31.9 ?g/g Cr; 40.4 ?g/L) of urinary SumAs were higher in Vieques samples than in the those from the general population of other countries. Among the three biomarkers of exposure, nail samples reflected better the exposure to iAs from seafood consumption with significantly higher average As concentrations in high (0.24 ?g/g) than low (0.12 ?g/g) seafood consumers. Multivariate results for As in nail samples (R (2) = 0.55, p &lt; 0.0001) showed a positive association with fish consumption, particularly for men, with levels increasing with years of residency in Vieques.",
Arsenic,656855,"Role of reactive oxygen species in skin carcinogenesis Abstract: Reactive oxygen species (ROS) are associated not only with initiation, but also with promotion and progression in the multistage carcinogenesis model. In the present review, we will focus on the involvement of ROS in skin carcinogenesis, especially that induced by ultraviolet (UV) radiation. UV-specific DNA damage has been well studied thus far. However, recent reports have revealed the previously unknown participation of oxidative stress in UV-induced skin carcinogenesis. Indeed, in addition to transition-type mutations at dipyrimidine sites, G:C to T:A transversions, which may be induced by the presence of 8-oxoguanine during DNA replication, are frequently observed in the ras oncogene and p53 tumor suppressor gene in human skin cancers of sun-exposed areas and in UV-induced mouse skin cancers. Recent studies have shown that not only UV-B, but also UV-A is involved in UV-induced carcinogenesis. A wide variety of biological phenomena other than direct influence by UV, such as inflammatory and immunological responses and oxidative modifications of DNA and proteins, appear to play roles in UV-induced skin carcinogenesis. Furthermore, it has become clear that genetic diseases such as xeroderma pigmentosum show deficient repair of oxidatively modified DNA lesions. The involvement of ROS in skin carcinogeneisis caused by arsenic and chemical carcinogens will also be discussed.",
Arsenic,1797803,"Temporal and spatial variation of arsenic species in the Dahuofang reservoir in northeast China Abstract: Overlying water, pore water, and sediment samples were collected from the Dahuofang reservoir in November 2011 and April 2012, respectively. Total arsenic and arsenic species including arsenite, arsenate, monomethylarsonic, and dimethylarsinic were analyzed by ICP-MS and HPLC-ICP-MS. The results indicated that the environments of the Dahuofang reservoir were in reduced conditions, arsenite was the predominant species in pore water and sediments in the reservoir. Arsenic concentrations in overlying water were very low in all the samples but showed different trend during the different time. In November, arsenic concentrations in the reservoir inlet were higher than that in the other sites, whereas arsenic showed accumulation from the upstream to downstream of the reservoir in samples collected in April. In pore water, arsenic concentrations were about 23 and 37 times higher than those in overlying water in November and April, respectively, and relatively high levels of arsenite were also detected in the pore water. In surface sediments, total arsenic and arsenic species content in the reservoir inlet showed the following decreasing order: R1?&gt;?R10?&gt;?R4. The results also showed that moderate ecological risks exist in pore water and sediments in the Dahuofang reservoir.",
Arsenic,1391106,"Programmed Cell Death, Apoptosis, and Birth Defects Abstract: It has long been recognized that cell death, termed programmed cell death (PCD), is an integral part of the development of virtually every tissue and organ during embryogenesis. The significance of PCD is highlighted by the observation that too little or too much PCD is associated with the subsequent development of birth defects. It is also well recognized that environmental agents capable of disrupting normal development (i.e., teratogens) often induce excessive cell death as an early event in the pathogenesis that eventually culminates in morphological/functional birth defects. Teratogen-induced cell death is also specific, i.e., some cells die while the majority of cells survive, and those that die are often associated with areas of PCD. My laboratory has focused on three questions relevant to the role of teratogen-induced cell death in the induction of abnormal development: 1) do developmental toxicants induce apoptosis in embryos destined to develop abnormally, 2) how do embryos perceive exposure to a developmental toxicant and then activate an appropriate cell death pathway, and 3) how do the majority of cells in the embryo escape a cell death fate? Relative to the first question, we have now shown that 4 different developmental toxicants, i.e., hyperthermia (physical agent), cyclophosphamide (DNA alkylating agent), sodium arsenite (heavy metal), and staurosporine (protein kinase c inhibitor), induce biochemical changes in early postimplantation mouse embryos that are considered hallmarks of apoptosis, i.e., release of cytochrome c from mitochondria, activation of caspases, cleavage of poly (ADP-ribose) polymerase (PARP), and internucleosomal DNA fragmentation. These results demonstrate that these developmental toxicants induce cell death by activating the intrinsic mitochondrial apoptotic pathway. Relative to the second question, we have probed known signal transduction pathways in an effort to understand the mechanisms by which developmental toxicants trigger apoptosis in early postimplantation murine embryos. Our initial efforts focused on mitogen-activated protein kinases (MAP kinases) belonging to the ERK, JNK, and p38 signaling pathways. Our data show that hyperthermia rapidly, but transiently, activates the ERK, JNK and p38 pathways, and that activation of these pathways precedes by several hours the release of cytochrome c and the activation of caspases. In contrast, cyclophosphamide and staurosporine fail to activate ERK and JNK, but do induce the reproducible activation of p38. More recently, we have shown that hyperthermia and cyclophosphamide activate p53, a wellknown regulator of cell proliferation and apoptosis. Relative to the third question, we have shown that heart cells from early postimplantation mouse embryos are completely resistant to the apoptotic stimulus initiated by these 4 developmental toxicants. The failure to undergo cell death in response to exposure to these teratogens is associated with the attenuated activation of p53 and failure to 1) release cytochrome c from mitochondria, 2) activate caspases, 3) cleave PARP, and 4) induce internucleosomal DNA fragmentation.",
Arsenic,1338896,"Prognostic value of uric acid in patients with Type 2 diabetes mellitus and coronary artery disease Abstract: Studies investigating the prognostic role of UA (uric acid) in patients with Type 2 diabetes mellitus have given conflicting findings. We undertook the present study to assess the association between UA and outcome in patients with Type 2 diabetes mellitus and CAD (coronary artery disease). The study included 3705 patients with diabetes mellitus and angiography-proven CAD. UA was measured before coronary angiography. The primary outcome was 1-year all-cause mortality. The UA concentration [median (25th-75th quartiles)] was 6.44 mg/dl (5.40-7.70 mg/dl). There were 264 deaths (7.1%) during follow-up: 45 deaths in patients of the first UA quartile, 43 deaths in patients of the second UA quartile, 51 deaths in patients of the third UA quartile and 125 deaths in patients of the fourth UA quartile {Kaplan-Meier estimates of mortality, 5.1, 4.8, 5.6 and 14.0% respectively; unadjusted HR (hazard ratio), 2.81 [95% CI (confidence interval), 2.21-3.58]; P&lt;0.001 for fourth quartile compared with first-third quartiles combined}. In the multivariable analysis, UA predicted all-cause mortality with an adjusted HR of 1.29 (95% CI, 1.12-1.48; P&lt;0.001), for each S.D. increase in the logarithmic scale of UA level. The inclusion of UA in the multivariable model alongside known cardiovascular risk factors and other relevant variables increased the discriminatory power of the model regarding prediction of all-cause mortality [absolute and relative IDI (integrated discrimination improvement) 0.034 and 20.5% respectively; P&lt;0.001]. In conclusion, in patients with Type 2 diabetes mellitus and confirmed CAD, elevated levels of UA predict mortality independently of known cardiovascular risk factors.",
Arsenic,1350731,"TOXICITY OF ARSENIC, MOLYBDENUM AND SELENIUM COMBINATIONS TO CERIODAPHNIA-DUBIA Abstract: BIOSIS COPYRIGHT: BIOL ABS. Previous research done on the effects of contaminant mixtures has been evaluated primarily by using acute exposures. While this was an important initial step, characterizing the effects of chronic exposures of these mixtures is more environmentally pragmatic. This study examined the sublethal interactive effects of arsenic (As), molybdenum (Mo), and selenium (Se) on Ceriodaphnia dubia using the three-brood static renewal toxicity test. A complete factorial design experiment using four levels (zero, IC12.5, IC25, and IC50 values) of each metal was performed to investigate the binary and tertiary interactions of these metals on C. dubia survival and fecundity. Results indicate three-way interactive effects in survival and fecundity with the strongest effect exhibited by Se. Molybdenum and As in binary combinations appear to be strongly antagonistic in their effects on C. dubia, even at their respective IC50 concentrations. However, generally the addition of Se to As-Mo mi",
Arsenic,1350501,Removal of Arsenic from Simulated Groundwater Using GAC-Ca in Batch Reactor: Kinetics and Equilibrium Studies Abstract: ,
Arsenic,1240366,"Homeostatic regulation of elemental stoichiometry by Lemna gibba L. G3 when nutrient interact with toxic metals Abstract: We investigated responses of Lemna gibba L. to exposure to UO(2)(2+) and AsO(4)(3-) under variable PO(4)(3-) concentration. Total plant phosphorus (P(tot)) in L. gibba and accumulation of dissolved organic carbon (DOC) in the media were quantified and tested for correlation with plant yield and initial concentrations of PO(4)(3-), UO(2)(2+) and AsO(4)(3-). The accumulation of DOC in medium was high under low PO(4)(3-) supply and increased loading of either UO(2)(2+) or AsO(4)(3-). The P(tot) was low in high initial concentration of UO(2)(2+) and AsO(4)(3-) as well under acute low PO(4)(3-) supply. The DOC accumulation correlated negatively to the P(tot). This reveals interaction between PO(4)(3-) and UO(2)(2+) or AsO(4)(3-) in the medium interferes with the uptake process of PO(4) (3-). Hence, the DOC accumulation is exudation of low molecular weight organic substance by L. gibba in response to the reduced P(tot): biomass ratio (carbon in the yield) due to delimited acquisition of phosphorus from the medium. It is a homeostatic regulation of the stoichiometry, which is disturbed during the interaction between PO(4)(3-) and UO(2)(2+) or AsO(4)(3-). Further investigations are necessary to relate these interactions to traditional resource stoichiometry elements of C, N, and P.",
Arsenic,1936048,"Bifunctional resin-ZVI composites for effective removal of arsenite through simultaneous adsorption and oxidation Abstract: Bifunctional resin-supported nanosized zero-valent iron (N-S-ZVI) composite was developed by combining the oxidation properties of nZVI/O2 with adsorption features of iron oxides and anion-exchange resin N-S. In batch culture experiments, N-S and the N-S-ZVI composite were examined for As(III) and As(V). The results reveal that ZVI in the composite played a key role in enhancing As(III) removal. The N-S-ZVI composites could oxidize more toxic As(III) to less toxic As(V) with high efficiency under ambient conditions without the need of noble metals. At the same time, the oxidized As(V) could be effectively removed by adsorption onto the surface of composites. The mechanisms for the oxidation of As(III) to As(V) and the simultaneous removal of As(V) are proposed. In order to investigate the potential performance of N-S-ZVI in practical use, the effects of solution pH and coexisting anions on arsenite removal and on fixed-bed column treatment of simulated waters were studied. All the results indicated that the bifunctional composites have a great potential for As(III) removal from contaminated waters.",
Arsenic,1034088,"Male characteristics on female mud snails caused by antifouling bottom paints Abstract: This study continues an investigation of an anatomical abnormality, named 'imposex', which consists of a superimposition of male characteristics on to a functionally normal female reproductive anatomy of the dioecious snail Nassarius obsoletus Say. Imposex is prevalent in natural populations living near yacht basins and rarely found distant from them. In the current study caged snails were transferred between a yacht basin and a distant 'clean' locality where the natural population of snails was normal. Imposex was induced in some normal snails kept at the marina and suppressed, but not lost in abnormal snails kept at the clean locality. A similar positive result was obtained in the laboratory by exposing normal snails to organotin-containing antifouling paints and abnormal snails to clean sea water. Results were negative in parallel tests of various marina-associated materials which did not contain organotin. The laboratory studies have thus identified a causative factor for the anatomical abnormalities common near yacht basins in the natural environment. They also provide a rare, if not unique, example of a chemical agent which causes the appearance of superfluous anatomical features in an animal.",
Arsenic,1347893,"Protective role of nitric oxide against arsenic-induced damages in germinating mung bean seeds Abstract: Nitric oxide (NO) is a bioactive gaseous, multifunctional molecule playing a central role and mediating a variety of physiological processes and responses to biotic and abiotic stresses including heavy metals. The present study investigated whether NO applied exogenously as sodium nitroprusside (SNP) has a protective role against arsenic (As) toxicity (applied as sodium arsenate) in Vigna radiata (mung bean) germinating seeds. Treatment with 75 ?M SNP significantly improved mung bean seed germination, growth, and decreased the As-accumulation. Furthermore, As-induced oxidative stress measured in terms of malondialdehyde and H2O2 contents was lesser upon supplementation of SNP indicating a reactive oxygen species scavenging activity of NO. In addition, supplementation of SNP markedly decreased the activity of superoxide dismutase and stimulated catalase, ?-amylase, protease and slightly changed the H+-ATPase activity.",
Arsenic,8742,"In vitro solubility and in vivo toxicity of gallium arsenide Abstract: The in vitro solubilities of gallium arsenide (GaAs) and its metal oxides were arsenic(III) oxide greater than GaAs much greater than gallium(III) oxide. GaAs dissolution was also dependent upon the type and concentration of buffer anion. The amount of arsenic dissolved in 12 hr by various aqueous media was 0.2 M phosphate buffer greater than or equal to 0.1 M phosphate buffer greater than Krebs-Hensleit buffer greater than distilled H2O greater than HCl-KCl buffer. GaAs was apparently soluble under in vivo conditions. Blood arsenic concentrations in rats 14 days after intratracheal instillation of 10, 30, or 100 mg/kg GaAs were 5.5, 14.3, and 53.6 micrograms/ml, respectively; gallium was not detected at any doses. An increase in lung wet weight at 14 days was dose dependent with these organs retaining 17 to 42% of the dose as gallium or arsenic. Excretion of gallium and arsenic was limited to the feces. Urinary porphyrin concentrations and body weight, monitored as indices of toxicity, were significantly altered over the 14-day study. The analysis of porphyrins revealed that uroporphyrin replaced coproporphyrin as the primary urinary metabolite. Rats receiving 10, 100, or 1000 mg/kg GaAs po exhibited similar signs of toxicity. Blood arsenic concentrations at 14 days were 3.5, 6.8, and 17.6 micrograms/ml, respectively. Porphyria was increased, and body weight was decreased at 1000 mg/kg GaAs. These values were equivalent to those obtained with an intratracheal dose of 10 to 30 mg/kg GaAs. Our results showed that pulmonary and po exposure to GaAs resulted in systemic arsenic intoxication. The finding that urinary uroporphyrin concentrations were greater than coproporphyrin concentrations may serve as a sensitive indicator for GaAs exposure.",
Arsenic,1508651,"Acceptance and use of eight arsenic-safe drinking water options in Bangladesh Abstract: Arsenic contamination of drinking water is a serious public health threat. In Bangladesh, eight major safe water options provide an alternative to contaminated shallow tubewells: piped water supply, deep tubewells, pond sand filters, community arsenic-removal, household arsenic removal, dug wells, well-sharing, and rainwater harvesting. However, it is uncertain how well these options are accepted and used by the at-risk population. Based on the RANAS model (risk, attitudes, norms, ability, and self-regulation) this study aimed to identify the acceptance and use of available safe water options. Cross-sectional face-to-face interviews were used to survey 1,268 households in Bangladesh in November 2009 (n?=?872), and December 2010 (n?=?396). The questionnaire assessed water consumption, acceptance factors from the RANAS model, and socioeconomic factors. Although all respondents had access to at least one arsenic-safe drinking water option, only 62.1% of participants were currently using these alternatives. The most regularly used options were household arsenic removal filters (92.9%) and piped water supply (85.6%). However, the former result may be positively biased due to high refusal rates of household filter owners. The least used option was household rainwater harvesting (36.6%). Those who reported not using an arsenic-safe source differed in terms of numerous acceptance factors from those who reported using arsenic-safe sources: non-users were characterized by greater vulnerability; showed less preference for the taste and temperature of alternative sources; found collecting safe water quite time-consuming; had lower levels of social norms, self-efficacy, and coping planning; and demonstrated lower levels of commitment to collecting safe water. Acceptance was particularly high for piped water supplies and deep tubewells, whereas dug wells and well-sharing were the least accepted sources. Intervention strategies were derived from the results in order to increase the acceptance and use of each arsenic-safe water option.",
Arsenic,1379929,The effect of arsenical vesicants on the respiration of skin Abstract: ,
Arsenic,1337521,"A core metabolic enzyme mediates resistance to phosphine gas Abstract: Phosphine is a small redox-active gas that is used to protect global grain reserves, which are threatened by the emergence of phosphine resistance in pest insects. We find that polymorphisms responsible for genetic resistance cluster around the redox-active catalytic disulfide or the dimerization interface of dihydrolipoamide dehydrogenase (DLD) in insects (Rhyzopertha dominica and Tribolium castaneum) and nematodes (Caenorhabditis elegans). DLD is a core metabolic enzyme representing a new class of resistance factor for a redox-active metabolic toxin. It participates in four key steps of core metabolism, and metabolite profiles indicate that phosphine exposure in mutant and wild-type animals affects these steps differently. Mutation of DLD in C. elegans increases arsenite sensitivity. This specific vulnerability may be exploited to control phosphine-resistant insects and safeguard food security.",
Arsenic,2278982,"Tetra-arsenic tetra-sulfide (As4S4) promotes apoptosis in retinoid acid -resistant human acute promyelocytic leukemic NB4-R1 cells through downregulation of SET protein Abstract: Tetra-arsenic tetra-sulfide (As4S4) is an arsenic compound with antitumor activity, especially in acute promyelocytic leukemia (APL) that are resistant to retinoic acid (RA). Although recent studies have revealed that the therapeutic action of As4S4 is closely associated with the induction of cellular apoptosis, the exact molecular mechanism underlying this action in RA-resistant APL remains to be clarified. In this study, we found that As4S4-induced apoptosis was accompanied by reduced mRNA and protein expression of SET gene in RA-resistant NB4-R1 cells. Moreover, RNAi knockdown of SET gene further promoted As4S4-induced apoptosis, while SET overexpression recovered the cell viability, suggesting that As4S4 induces apoptosis through the reduction of SET protein in NB4-R1 cells. We also observed that the knockdown of SET gene resulted in the upregulation of protein phosphatase 2 (PP2A) expression and the downregulation of promyelocytic leukemia and retinoic acid receptor ? fusion gene (PML-RAR?) expression, which were enhanced by As4S4 treatments. By contrast, overexpression of SET gene resulted in PP2A downregulation and PML-RAR? upregulation, which were abolished by As4S4 pretreatment. Since PP2A is a proapoptotic factor and PML-RAR? is an antiapoptotic factor, our results suggest that As4S4-induced apoptosis in RA-resistant NB4-R1 cells is through the downregulation of SET protein expression, which, in turn, increases PP2A and reduces PML-RAR? expressions to lead to cell apoptosis.",
Arsenic,2064266,"Characterization of a novel composite staphylococcal cassette chromosome mec (SCCmec-SCCcad/ars/cop) in the neonatal sepsis-associated Staphylococcus capitis pulsotype NRCS-A Abstract: Multi-resistant Staphylococcus capitis pulsotype NRCS-A has been reported to be a major pathogen causing nosocomial bacteremia in preterm infants. We report that the NRCS-A strain CR01 harbors a novel 60.9 kb composite SCCmec element, composed of an SCCmec with strong homologies to S. aureus ST398 SCCmec and of an SCCcad/ars/cop harboring resistance genes for cadmium, arsenic and copper. Whole genome-based comparisons of published S. capitis strains suggest that strain CR01 acquired the two elements independently.",
Arsenic,536338,"Altered iron homeostasis involvement in arsenite-mediated cell transformation Abstract: Chronic exposure to low doses of arsenite causes transformation of human osteogenic sarcoma (HOS) cells. Although oxidative stress is considered important in arsenite-induced cell transformation, the molecular and cellular mechanisms by which arsenite transforms human cells are still unknown. In the present study, we investigated whether altered iron homeostasis, known to affect cellular oxidative stress, can contribute to the arsenite-mediated cell transformation. Using arsenite-induced HOS cell transformation as a model, it was found that total iron levels are significantly higher in transformed HOS cells in comparison to parental control HOS cells. Under normal iron metabolism conditions, iron homeostasis is tightly controlled by inverse regulation of ferritin and transferrin receptor (TfR) through iron regulatory proteins (IRP). Increased iron levels in arsenite transformed cells should theoretically lead to higher ferritin and lower TfR in these cells than in controls. However, the results showed that both ferritin and TfR are decreased, apparently through two different mechanisms. A lower ferritin level in cytoplasm was due to the decreased mRNA in the arsenite-transformed HOS cells, while the decline in TfR was due to a lowered IRP-binding activity. By challenging cells with iron, it was further established that arsenite-transformed HOS cells are less responsive to iron treatment than control HOS cells, which allows accumulation of iron in the transformed cells, as exemplified by significantly lower ferritin induction. On the other hand, caffeic acid phenethyl ester (CAPE), an antioxidant previously shown to suppress As-mediated cell transformation, prevents As-mediated ferritin depletion. In conclusion, our results suggest that altered iron homeostasis contributes to arsenite-induced oxidative stress and, thus, may be involved in arsenite-mediated cell transformation. (c) 2005 Elsevier Inc. All rights reserved.",
Arsenic,1033112,"A complex effect of arsenite on the formation of alpha-ketoglutarate in rat liver mitochondria Abstract: This investigation presents disturbances of the mitochondrial metabolism by arsenite, a hydrophilic dithiol reagent known as an inhibitor of mitochondrial alpha-keto acid dehydrogenases. Arsenite at concentrations of 0.1-1.0 mM was shown to induce a considerable oxidation of intramitochondrial NADPH, NADH, and glutathione without decreasing the mitochondrial membrane potential. The oxidation of NAD(P)H required the presence of phosphate and was sensitive to ruthenium red, but occurred without the addition of calcium salts. Mitochondrial reactions producing alpha-ketoglutarate from glutamate and isocitrate were modulated by arsenite through various mechanisms: (i) both glutamate transaminations, with oxaloacetate and with pyruvate, were inhibited by accumulating alpha-ketoglutarate; however, at low concentrations of alpha-ketoglutarate the aspartate aminotransferase reaction was stimulated due to the increase of NAD+ content; (ii) the oxidation of isocitrate was stimulated at its low concentration only, due to the oxidation of NADPH and NADH; this oxidation was prevented by concentrations of citrate or isocitrate greater than 1 mM; (iii) the conversion of isocitrate to citrate was suppressed, presumably as a result of the decrease of Mg2+ concentration in mitochondria. Thus the depletion of mitochondrial vicinal thiol groups in hydrophilic domains disturbs the mitochondrial metabolism not only by the inhibition of alpha-keto acid dehydrogenases but also by the oxidation of NAD(P)H and, possibly, by the change in the ion concentrations.",
Arsenic,23767,"Chronic exposure to sour gas emissions: meeting a community concern with epidemiologic evidence Abstract: For 25 years residents of a rural area in southwestern Alberta have complained of health problems attributed to sour gas emissions from nearby natural gas refineries. We undertook a large epidemiologic study of the current health status and the selected morbidity rates among 2152 people in the exposed area. We established two comparison groups: one was a demographically similar unexposed population and the other a demographically different group also exposed to sour gas emissions in another region. The methods included a cross-sectional survey of current residents and separate historical cohort studies involving registry linkage to investigate cancer incidence and all-cause mortality. The cross-sectional survey involved a comprehensive health questionnaire, standardized clinical examinations by physicians blinded to the subjects' symptoms and concerns, and several laboratory tests. We were able to contact just under 60% of the people who we knew had moved from each area since 1958 and found no evidence of selective migration for health reasons. Although the residents of the exposed area reported an excess number of symptoms and health problems there were no significant differences in the mortality rate, incidence of cancer, reproductive problems, major ailments, hair levels of arsenic and certain metals or respiratory function between the groups.",
Arsenic,2278460,"Application of a two-site ideal model for the prediction of As-SO4-Cl ion exchange equilibria Abstract: Ion exchange processes are effective for the removal of arsenic (As) from drinking water. However, the As uptake capacity of ion exchange resins is affected by the presence of other anions such as sulphates and nitrates. As these ions are typically found in groundwater, the design of ion exchange process aimed at removing As from groundwater may be affected by their presence. Therefore, to properly design an ion exchange process for As removal, it is important to characterise the ion exchange equilibria of As in solution in the presence of competing anions. This paper was aimed at obtaining a deeper understanding of the binary equilibria of As(V)Cl- and SO42-/Cl- and of the ternary equilibria of As(V)/SO42-/Cl-. To this purpose, a series of batch tests were carried out at different values of the total solution normality. These data were combined with those obtained through continuous flow column tests performed to collect equilibrium data over the entire ionic fraction domain. The equilibrium data were then described using two different models based on the assumption of ideal behaviour of both the liquid and the adsorbed phases: in the first model the resin was considered to have only one type of binding-sites, where two types of binding sites were assumed by the second model, named double-selectivity model. Among these two models, the latter provided the best fitting of binary equilibrium data for both As chlorides and sulphate chlorides systems. However, the same model was unable to fit the experimental data of As in the ternary system As(V)/SO42-/Cl- with a satisfactory agreement probably due to the presence of non-ideality which the model did not account for.",
Arsenic,2149128,"Oxidation of As(III) to As(V) using ozone microbubbles Abstract: The use of ozone in the treatment of water and wastewater is rapidly increasing due to its high oxidizing power. Arsenic is one the most toxic elements found in water. As(III) and As(V) are the major sources of arsenic poisoning. It is known that As(V) can be more easily removed from water by adsorptive methods than As(III). In this work, oxidation of more toxic As(III) to less toxic As(V) was studied in a pilot-plant by using ozone microbubbles. The microbubbles were effective in dissolving ozone in water. The oxidation was fast over a wide range of pH (e.g., 4-9). The role of hydroxyl radical in the oxidation of As(III) under acidic conditions was investigated by using 2-propanol as the hydroxyl radical scavenger. Under acidic conditions, the addition of 2-propanol slowed down the oxidation, which proves that hydroxyl radicals were involved in the oxidation process. The effect of carbonate ions on the rate of oxidation was investigated. It was found that the generation of carbonate ion radical from the carbonate ion accelerated the oxidation of As(III). The kinetics of oxidation of As(III) by ozone was studied.",
Arsenic,1018163,"Arsenic resistance operon structure in Leptospirillum ferriphilum and proteomic response to arsenic stress Abstract: The response of Leptospirillum ferriphilum ML-04 to arsenic stress was analyzed using two-dimensional electrophoresis (2-DE), matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Thirty-eight of 65 significantly differentially expressed arsenic response proteins were identified, and 25 of them have known functions. Three proteins are arsenic resistance system (ARS) member proteins. Two ars operons appear to be present in this strain. In addition to the ARS system, phosphate regulation and glutathione (GSH) synthesis appear involved in As[V] and As[III] tolerance, respectively. These findings provide information potentially useful for the genetic engineering of arsenic resistant organisms.",
Arsenic,1019121,"Folic acid protects SWV/Fnn embryo fibroblasts against arsenic toxicity Abstract: It has been proposed that arsenic exerts its toxic effects, in part, by perturbing cellular methyl metabolism. Based on the hypothesis that folic acid treatment will attenuate the cytotoxic and growth inhibitory effects of arsenic, SWV/Fnn embryo fibroblasts were cultured in media supplemented with various concentrations of folic acid during treatment with sodium arsenite or dimethylarsinic acid (DMA). It was found that folic acid protects SWV/Fnn embryo fibroblasts from sodium arsenite and DMA cytotoxicity in a dose-dependent manner. In contrast, folic acid supplementation has no effect on toxicity resulting from treatment with ethanol or staurosporine, suggesting that folic acid is not generally protective against necrosis and apoptosis. Although folic acid protects against acute arsenic toxicity, this agent shows a modest and delayed ability to attenuate the growth inhibitory effect of arsenic on these cells. These results support a model in which perturbations of methyl metabolism contribute to the acute cytotoxicity of arsenic.",
Arsenic,1015857,"Elevated levels of plasma Big endothelin-1 and its relation to hypertension and skin lesions in individuals exposed to arsenic Abstract: Chronic arsenic (As) exposure affects the endothelial system causing several diseases. Big endothelin-1 (Big ET-1), the biological precursor of endothelin-1 (ET-1) is a more accurate indicator of the degree of activation of the endothelial system. Effect of As exposure on the plasma Big ET-1 levels and its physiological implications have not yet been documented. We evaluated plasma Big ET-1 levels and their relation to hypertension and skin lesions in As exposed individuals in Bangladesh. A total of 304 study subjects from the As-endemic and non-endemic areas in Bangladesh were recruited for this study. As concentrations in water, hair and nails were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The plasma Big ET-1 levels were measured using a one-step sandwich enzyme immunoassay kit. Significant increase in Big ET-1 levels were observed with the increasing concentrations of As in drinking water, hair and nails. Further, before and after adjusting with different covariates, plasma Big ET-1 levels were found to be significantly associated with the water, hair and nail As concentrations of the study subjects. Big ET-1 levels were also higher in the higher exposure groups compared to the lowest (reference) group. Interestingly, we observed that Big ET-1 levels were significantly higher in the hypertensive and skin lesion groups compared to the normotensive and without skin lesion counterpart, respectively of the study subjects in As-endemic areas. Thus, this study demonstrated a novel dose-response relationship between As exposure and plasma Big ET-1 levels indicating the possible involvement of plasma Big ET-1 levels in As-induced hypertension and skin lesions.",
Arsenic,2149319,Human Health Handbooks Arsenic in the hair Abstract: ,
Arsenic,1579278,"A facile template free solution approach for the synthesis of dypingite nanowires and subsequent decomposition to nanoporous MgO nanowires with excellent arsenate adsorption properties Abstract: In this paper, one-dimensional (1-D) dypingite (hydrated magnesium carbonate hydroxide, Mg5(CO3)4(OH)2·5H2O) nanowires with several hundreds micrometers in length were synthesized at 100 °C by a simple solution method without using any template or catalyst for the first time. A plausible diffusion growth model for the growth of the dypingite nanowires was proposed. The influences of the magnesium ion concentrations and the magnesium sources on the structures of the products were also studied. The as-synthesized nanowires were an excellent precursor for the fabrication of 1-D nanoporous magnesium oxide (MgO) nanowires via a simple thermal transformation process. Room temperature photoluminescence studies suggest that the nanoporous MgO nanowires show a strong ultraviolet emission and a weak blue emission. The adsorption properties of the porous MgO nanowires were investigated for As(V) removal. A high As(V) adsorption capacity of 384.6 mg g?1 was realized, which was resulted from the reaction between the As(V) species and MgO in aqueous solution.",
Arsenic,628475,"Active oxygen species are involved in the induction of micronuclei by arsenite in XRS-5 cells Abstract: The human carcinogen, arsenic, is genotoxic to mammalian cells in vitro. The mechanism is largely unknown, although the involvement of free radicals has been suggested. Since the X-ray sensitive Chinese hamster ovary cell line, XRS-5, is also sensitive to several free-radical generating agents, including H2O2, we have used this cell line to test whether the genotoxic effect of arsenite is mediated via the generation of active-oxygen species. The results indicate that the XRS-5 cells are more sensitive to arsenite in terms of cell-killing and micronucleus induction compared to the parental CHO-K1 cells. The level of arsenic uptake and release, the levels of elementary components for arsenic detoxification, glutathione and glutathione S-transferase activities in these two cell lines are very similar. The XRS-5 cells, however, were shown to have 6-fold lower catalase activity in comparison to CHO-K1 cells. Moreover, catalase could effectively reduce the frequency of arsenite-induced micronuclei. These results indicate that the low catalase activity may be an important reason why XRS-5 cells are more sensitive to the toxic effects of arsenite, and arsenite probably induces micronuclei via the overproduction of H2O2. The XRS-5 cells had a higher background level of micronuclei, and were also more sensitive to gamma-rays in terms of induction of micronuclei. Catalase, however, did not reduce the background level or the frequency of gamma-ray-induced micronuclei. Therefore, the lower catalase activity seems to bear little relation to the high background level of micronuclei and the hypersensitivity to gamma-rays in micronucleus induction in XRS-5 cells.",
Arsenic,1019939,"Health survey of former workers in a Norwegian coke plant: Part. 1. Estimation of historical exposures Abstract: <strong>OBJECTIVE: </strong>To estimate historical exposure levels at a coke plant for all agents considered to be of importance for epidemiological studies of mortality and cancer incidence.<br /><br /><strong>METHODS: </strong>Time weighted average exposure (8 h TWA) was estimated based on personal measurements for polycyclic aromatic hydrocarbons (PAHs) and carbonaceous particulates. Exposure to quartz was estimated relative to the concentration of carbonaceous particulates. These estimates were adjusted for the use of airstream helmets. Exposure to other agents were estimated qualitatively (asbestos, benzene, and arsenic) or semi-quantitatively (carbon monoxide (CO) and heat) based on measurements and other indicators of exposure.<br /><br /><strong>RESULTS: </strong>Exposure to PAHs was highest for those who worked at the top of the ovens (300 micrograms/m3) in the period from 1970-6. The estimated PAH exposure was reduced to an average of 65 micrograms/m3 after the introduction of exposure control measures in 1976. The estimates for carbonaceous particulates ranged from 1 to 16 mg/m3, with the highest exposure for workers at the top of the ovens and at the coke screening station.<br /><br /><strong>CONCLUSIONS: </strong>The exposure of greatest concern in this study is to PAHs, but exposures to carbonaceous particulates and CO may also be of importance. The major limitations of this study are the lack of personal measurements before 1975 and the total lack of measurements for some of the exposed categories of workers. Despite these limitations, we think that this assessment reflects the actual exposures for most of the former employees. The assessment thus provides a reasonable tool for the subsequent epidemiological study and for future epidemiological follow up studies at the coke plant.",
Arsenic,1677542,"Chronic arsenic exposure and blood glutathione and glutathione disulfide concentrations in Bangladeshi adults Abstract: <strong>BACKGROUND: </strong>In vitro and rodent studies have shown that arsenic (As) exposure can deplete glutathione (GSH) and induce oxidative stress. GSH is the primary intracellular antioxidant; it donates an electron to reactive oxygen species producing glutathione disulfide (GSSG). Cysteine (Cys) and cystine (CySS) are the predominant thiol/disulfide redox couple found in human plasma. Arsenic, GSH, and Cys are linked in several ways. First, GSH is synthesized via the transulfuration pathway and Cys is the rate limiting substrate. Second, intermediates of the methionine cycle regulate both the transulfuration pathway and As methylation. Third, GSH serves as the electron donor for reduction of arsenate to arsenite. Fourth, As has a high affinity for sulfhydryl groups and therefore binds to GSH and Cys.<br /><br /><strong>OBJECTIVES: </strong>To test the hypotheses that As exposure is associated with decreases in GSH and Cys and increases in GSSG and CySS, i.e., a more oxidized environment.<br /><br /><strong>METHODS: </strong>For this cross-sectional study, the Folate and Oxidative Stress Study, we recruited a total of 378 participants from each of 5 water As categories: <10 (n=76), 10-100 (n=104), 101-200 (n=86), 201-300 (n=67), and >300 µg/L (n=45). Concentrations of GSH, GSSG, Cys, and CySS were measured using HPLC.<br /><br /><strong>RESULTS: </strong>An interquartile range (IQR) increase in water As was negatively associated with blood GSH (mean change = -25.4 µmol/L; 95% CI: -45.3, -5.31) and plasma CySS (mean change = -3.00 µmol/L; 95% CI: -4.61, -1.40). Similar associations were observed with urine and blood As. There were no significant associations between As exposure and blood GSSG or plasma Cys.<br /><br /><strong>CONCLUSIONS: </strong>The observed associations are consistent with the hypothesis that As may influence concentrations of GSH and other non-protein sulfhydryls through binding and irreversible loss in bile and/or possibly in urine.",
Arsenic,1519132,"Role of hepatic and pancreatic oxidative stress in arsenic induced diabetic condition in Wistar rats Abstract: Arsenic, a potent environmental toxicant has been reported to induce diabetes mellitus, but its potential biological mechanism(s) has not been much investigated. The present study was designed to correlate pancreatic and hepatic oxidative stress with arsenic induced diabetes mellitus in experimental animals. Male albino Wistar rats were administered with low (1.5 mg kg(-1) b.wt.) and high (5.0 mg kg(-1) b.wt.) sodium arsenite orally for 4 week. Hyperglycemic condition was observed in arsenic exposed groups as indicated by increased (P &lt; 0.001) fasting plasma glucose, glycosylated hemoglobin (HbA1c) and impaired glucose tolerance (IGT), which were accompanied by an increase in the level of lipid peroxidation (P &lt; 0.001), protein oxidation (P &lt; 0.05 at low dose and P &lt; 0.001 at high dose) and nitric oxide (NO) (P &lt; 0.001) in hepatic and pancreatic tissue compared to control. Furthermore, superoxide dismutase (SOD) (P &lt; 0.001), catalase (CAT) (P &lt; 0.001) and glutathione-S-transferase (GST) (P &lt; 0.05 at low dose and P &lt; 0.001 at high dose) activities were elevated, while glutathione peroxidase (GPx) (P &lt; 0.05 at low dose and P &lt; 0.001 at high dose) and GSH level showed significant (P &lt; 0.001) depletion in both studied tissue of arsenic exposed rats compared to control. Arsenic induced hepatotoxicity was manifested by an increase (P &lt; 0.001) in serum ALT, AST and ALP. Arsenic exposure leads to accumulation of arsenic (P &lt; 0.05) and significant (P &lt; 0.05) depletion of copper and zinc level in hepatic and pancreatic tissue as compared to control. Our data suggests that sub-chronic arsenic exposure induces diabetic condition which may be mediated due to increased oxidative stress in hepatic and pancreatic tissue.",
Arsenic,1677588,"Arsenic toxicosis in cattle: Meta-analysis of 156 cases Abstract: BACKGROUND: Arsenic toxicosis is uncommon in cattle and successful treatment is rarely reported. OBJECTIVES: This analysis reviews all cases of acute arsenic toxicosis in cattle reported in the literature and describes cases from Purdue University that had a favorable outcome. Clinical presentation of the disease, treatments, and variables associated with survival are described. ANIMALS: One hundred and fifty-six cattle with arsenic toxicosis from 16 outbreaks. METHODS: Meta-analysis. RESULTS: The most common clinical signs were sudden death (68%), diarrhea (33%), ataxia (29%), dehydration (22%), and respiratory distress (4%). The most common clinicopathologic abnormalities included azotemia (100%), hematuria (100%), increased liver enzyme activity (86%), and increased hematocrit (60%). One percent of cattle survived and the survival time for nonsurvivors ranged from 20 hours to 21 days. None of the clinical signs or clinicopathologic findings was associated with survival. Treatment was attempted in 24% of cases and was not associated with survival (P = .055), but administration of an antidote and administration of fluids were associated with better outcome (P = .036 and P = .009, respectively). In the animals presented to Purdue University, treatment with IV fluids and sodium thiosulfate resulted in decreased blood arsenic concentrations in all animals (P = .009) and a survival rate of 50%. CONCLUSIONS AND CLINICAL IMPORTANCE: Although acute arsenic toxicosis has a poor prognosis, survival is possible if aggressive fluid therapy and antidotes are administered.",
Arsenic,1019314,"Arsenic inhibits NF-kappaB-mediated gene transcription by blocking IkappaB kinase activity and IkappaBalpha phosphorylation and degradation Abstract: The inflammatory cytokine, TNF-alpha, induces IL-8 gene transcription via a mechanism involving proteasome-mediated IkappaBalpha degradation and NF-kappaB activation. Here, we investigated whether arsenic, which has been shown to inhibit the ubiquitin-proteasome pathway, could inhibit TNF-alpha-mediated increases in IL-8 expression. Using RT-PCR, we show that the addition of TNF-alpha to human bronchial epithelial (BEAS 2B) or embryonic kidney (HEK293) cells resulted in increased steady-state levels of IL-8 mRNA. This was preceded by a rapid decrease in cellular IkappaBalpha levels, as demonstrated by Western analysis, and an increase in nuclear levels of NF-kappaB, as demonstrated by gel shift analysis. Further demonstrating the activation of NF-kappaB, TNF-alpha induced the transcription of a NF-kappaB-dependent reporter gene. Exposing the cells to 500 microM arsenite, prior to adding TNF-alpha, completely inhibited IkappaBalpha degradation, NF-kappaB translocation, NF-kappaB-dependent gene transcription, and transcription of the endogenous gene for IL-8. In comparison with the proteasome inhibitor MG-132, which does not affect the phosphorylation and ubiquitination of IkappaBalpha, arsenite inhibited the phosphorylation of IkappaBalpha. Furthermore, arsenite directly blocked the activity of IKK, the kinase responsible for IkappaBalpha phosphorylation. These studies demonstrate that high levels of arsenic may inhibit NF-kappaB-mediated gene transcription by specifically blocking IKK activity, thereby limiting the phosphorylation and subsequent degradation of the NF-kappaB inhibitor, IkappaBalpha.",
Arsenic,1026040,"Sodium arsenite-induced inhibition of cell proliferation is related to inhibition of IL-2 mRNA expression in mouse activated T cells Abstract: A proposed mechanism for the As-induced inhibition of cell proliferation is the inhibition of IL-2 secretion. However, the effects of arsenite on IL-2 mRNA expression or on the ERK pathway in activated-T cells have not yet been described. We examined the effect of arsenite on IL-2 mRNA expression, cell activation and proliferation in PHA-stimulated murine lymphocytes. Arsenite (1 and 10 microM) decreased IL-2 mRNA expression, IL-2 secretion and cell proliferation. Arsenite (10 microM) strongly inhibited ERK-phosphorylation. However, the partial inhibition (50%) of IL-2 mRNA produced by 1 microM, consistent with the effects on IL-2 secretion and cell proliferation, could not be explained by the inhibition of ERK-phosphorylation, which was not affected at this concentration. The inhibition of IL-2 mRNA expression caused by 1 microM could be associated to effects on pathways located downstream or parallel to ERK. Arsenite also decreased early activation (surface CD69+ expression) in both CD4+ and CD8+, and decreased total CD8+ count without significantly affecting CD4+, supporting that the cellular immune response mediated by cytotoxic T cells is an arsenic target. Thus, our results suggest that arsenite decreases IL-2 mRNA levels and T-cell activation and proliferation. However, further studies on the effects of arsenite on IL-2 gene transcription and IL-2 mRNA stability are needed.",
Arsenic,1015983,"Characterization of Eyjafjallajökull volcanic ash particles and a protocol for rapid risk assessment Abstract: On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions.",
Arsenic,628515,"Increased micronuclei in exfoliated bladder cells of individuals who chronically ingest arsenic-contaminated water in Nevada Abstract: It is well established that inorganic arsenic is causally associated with lung cancer via inhalation and skin cancer via ingestion. Epidemiological evidence based on studies in Taiwan suggests that ingestion of inorganic arsenic may also cause other more fatal internal cancers, with the highest relative risks reported for bladder cancer. Here, we have used a biological marker of response, the micronucleus assay in exfoliated bladder cells, to evaluate the possible genotoxic effects of chronic arsenic ingestion on the bladder. The overall objective of this study was to compare the frequency of micronucleated cells in exfoliated bladder and buccal cells between a group of 18 individuals in Nevada who chronically ingested high levels of inorganic arsenic from their well water (average level, 1,312 micrograms/liter) and an individually matched control group with low exposure to arsenic (average level, 16 micrograms/liter). A 1.8-fold increase (90% confidence interval, 1.06-2.99) was observed in the weighted mean frequency of micronucleated bladder cells in the exposed group (2.79 per 1000 cells) compared with the unexposed group (1.57 per 1000 cells). In addition, the frequency of micronucleated bladder cells was positively associated with the urinary concentration of inorganic arsenic plus its methylated metabolites (Spearman correlation = 0.33; P = 0.03). In contrast, there was no increase in micronucleated buccal cells associated with arsenic ingestion (frequency ratio = 1.0; 90% confidence interval, 0.65-1.53). The results of this study provide evidence that chronic ingestion of high levels of inorganic arsenic in drinking water is associated with an increased frequency of micronucleated bladder cells. These findings are consistent with a genotoxic effect of arsenic on bladder cells, but a larger study is needed to confirm them.",
Arsenic,1597413,"Relative efficacies of insulin and poly (lactic-co-glycolic) acid encapsulated nano-insulin in modulating certain significant biomarkers in arsenic intoxicated L6 cells Abstract: The present study evaluates relative efficacies of insulin and PLGA-loaded-nano-insulin (NIn) in combating arsenic-induced impairment of glucose uptake, insulin resistance and mitochondrial dysfunction in L6 skeletal muscle cells. L6 cells were treated with 0.5mM sodium arsenite for 30min and then the cells were further treated with either 100nM insulin (standardized dose) or either of the two doses, 50nM and 100nM of nano-insulin. Various biomarkers like pyruvate-kinase and glucokinase, ATP/ADP ratio, mitochondrial membrane potential, cytosolic release of mitochondrial cytochrome c, cell membrane potential and calcium-ion level were studied and analyzed to ascertain the status of mitochondrial functioning in all experimental and control sets of L6 cells. The size, morphology and zeta potential of formulated NIn were determined by using dynamic light scattering, scanning electronic and atomic-force microscopies. Expression of signalling cascades like GLUT4, IRS1, IRS2, UCP2, PI3, and p38 was critically analyzed. Overall results suggested that both insulin and NIn improved mitochondrial functioning in arsenite-intoxicated L6 cells, NIn showing better effects at a much lower dose (at nearly 10-fold decreased dose) than that produced by insulin. Nano-insulin being non-toxic and effective at a much lesser dose, therefore, has potential for therapeutic use in the management of arsenic induced diabetes.",
Arsenic,1017455,"Evaluation of the effectiveness of arsenic screening promotion in private wells: a quasi-experimental study Abstract: The Eastern Townships (ETR) is a region in Québec (Canada) where the soil is naturally rich in arsenic (As). About a third of the people in the ETR obtain their water from a private well. A quasi-experimental design was used to compare two campaigns designed to promote As screening in well water: a mass-media campaign (MMC) followed or not by a community-based intervention (CBI). The MMC is based on a press release issued for the ETR, along with a leaflet on As made available on the Internet, and in strategic places. The CBI, formulated according to the factors of the Precede-Proceed model, was aimed at mobilizing local authorities and small media. It targets only one municipality; the intervention community (IC). Using a separate pre-post samples design, two population-based cross-sectional (pre-CBI and post-CBI) surveys were conducted by phone at 6-month intervals, by means of random samples. The samples counted, for the IC and the ETR, respectively, 87 and 156 well owners in pre-CBI, and 106 and 190 in post-CBI. The results in post-CBI showed that the proportion of well owners who had their water test increased by four times in the IC after (16% p = 0.004). When adjusting for age and gender among all the post-CBI respondents, As screening is related with intervention status (exposed to MMC and CBI; p ? 0.001) and on previous microbiological water analysis behavior (p ? 0.05), but is not related to knowledge. This study demonstrates the superiority of a community-based campaign over a MMC when environmental health is concerned.",
Arsenic,710865,"The association between arsenic exposure from drinking water and cerebrovascular disease mortality in Taiwan Abstract: Chronic arsenic exposure is associated with a variety of diseases, including cancer, peripheral vascular disease, and diabetes. However, its association with cerebrovascular diseases (CVD) has not yet been resolved. The aim of this study is to explore this association in Taiwan using nation-wide data.<br /><br /> We analyzed mortality data in Taiwan from 1971 to 2005 and choose two geographic areas with populations suffering from chronic exposure to arsenic in drinking water for study, the blackfoot disease endemic area (BFDEA) in the southwest and Lan-Yang Basin (LYB) in the northeast parts of Taiwan. The Chia-Yi and Tainan Counties, which surround the BFDEA, and the nation of Taiwan as a whole were used as reference populations. Direct standardized mortality rates and gender-specific indirect standardized mortality ratios (SMRs) were calculated for the four populations.<br /><br /> The direct standardized mortality rate for CVD in Taiwan decreased from 2.46/10(3) person-year in 1971 to 0.63/10(3) person-year in 2005, and women had significantly lower mortality than men (SMR = 0.80; p < 0.05). The CVD mortality rates of populations with chronic arsenic exposure were significantly higher than the reference populations (SMR ranging from 1.06 to 1.09 in men and 1.12 to 1.14 in women; p < 0.05). The BFDEA had higher CVD mortality rates than the LYB, with SMR = 1.05 (p < 0.05) in men and SMR = 1.04 (p = 0.05) in women.<br /><br /> In Taiwan, while CVD mortality decreased in both genders between 1971 and 2005, chronic arsenic exposure from drinking water was associated with increased risks of CVD.",
Arsenic,1519573,REPLICATION OF AN IVG PROTOCOL TO ESTIMATE BIOACCESSIBLE ARSENIC IN MATERIALS FROM A GOLD MINING AREA IN BRAZIL Abstract: ,
Arsenic,1016879,"Mitochondria, calcium and nitric oxide in the apoptotic pathway of esophageal carcinoma cells induced by As2O3 Abstract: In order to explore the early apoptotic signal messengers and to search the apoptotic pathway, the morphological and functional changes of mitochondria were examined, and nitric oxide (NO) and calcium ions (Ca2+) were measured in the course of apoptosis in esophageal carcinoma cells induced by As2O3. The esophageal carcinoma cell line SHEEC1, established by HPV in synergy with TPA in our laboratory, were cultured with serum-free medium in a culture flask, 24-well plate and small culture chambers, and added with As2O3 at 1, 3, 5 micromol/l. After 0, 2, 4, 8, 12, 24 h of drug adding the NO were measured from extracellular cultured medium and the SHEEC1 cells were collected from flasks for electron microscopic examination. Fluorescent intensity (FI) of rhodamine 123 (Rho123) labeled cells was detected using laser confocal scanning microscope (LCSM) for evaluation of mitochondrial membrane potential. Intracellular Ca2+ of cells in small culture chambers labeled with Fluo-3 dye were measured using LCSM over time. After adding As2O3, SHEEC1 cells revealed characteristic morphological and functional changes of mitochondria such as hyperplasia, swelling and disruption, accompanying decrease of transmembrane potential (FI of Rho123 decreased). The Ca2+ level increased at once after adding As2O3 and the NO concentration increased step by step till 24 h, then apoptotic morphology of cells occurred. The results suggest that by inducement of As2O3 increasing Ca2+ and NO, the apoptotic signal messengers, will initiate the mitochondria-dependent apoptotic pathway.",
Arsenic,1797770,"Engineering arsenic tolerance and hyperaccumulation in plants for phytoremediation using a PvACR3 transgenic approach Abstract: Arsenic (As) pollution is a global problem, and the plant-based cleanup of contaminated soils, called phytoremediation, is therefore of great interest. Recently, transgenic approaches have been designed to develop As phytoremediation technologies. Here, we used a one-gene transgenic approach for As tolerance and accumulation in Arabidopsis thaliana. PvACR3, a key arsenite (AsIII) antiporter in the As hyperaccumulator fern Pteris vittata, was expressed in Arabidopsis, driven by the CaMV 35S promoter. In response to As treatment, PvACR3-transgenic plants showed greatly enhanced tolerance. PvACR3-transgenic seeds could even germinate and grow in the presence of 80 ?M AsIII or 1200 ?M arsenate (AsV) treatments that were lethal to wild-type seeds. PvACR3 localizes to the plasma membrane in Arabidopsis and increases arsenite efflux into external media in short-term experiments. Arsenic determination showed that PvACR3 substantially reduced As concentrations in roots and simultaneously increased shoot As under 150 ?M AsV. When cultivated in AsV-containing soil (10 ppm As), transgenic plants accumulated approximately 7.5-fold more As in aboveground tissues than WT plants. This study provides important insights into the behavior of PvACR3 and the physiology of As metabolism in plants. Our work also provides a simple and practical PvACR3 transgenic approach for engineering As-tolerant and -hyperaccumulating plants for phytoremediation.",
Arsenic,2343533,"Geosorption of As(III) from Aqueous Solution by Red Clays: Kinetic Studies Abstract: The geosorption of As(III) on red clays from aqueous solution under different environmental conditions (i.e. initial concentration, pH and temperature) was studied. This process reached its equilibrium quickly (&lt; 120 min). A decrease of the percentage of adsorption was caused when the initial concentration was increased (0.1-10 mg As(III) L-1), in all the experimental pH levels (4-10). The optimal pH value for adsorption on red clays at 0.1 mg As(III) L-1 was 10, while for 10 mg As(III) L-1 was 4. There wasn't a significant effect of temperature on the As(III) adsorption. The kinetic pseudo-second order and the isothermal Langmuir were the models that best described the experimental data, suggesting an adsorption process in multistep. Likewise, there are not interactions between neighbor active sites on the red clay surface.",
Arsenic,627536,"Subhepatotoxic exposure to arsenic enhances lipopolysaccharide-induced liver injury in mice Abstract: Exposure to arsenic via drinking water is a serious health concern in the US. Whereas studies have identified arsenic alone as an independent risk factor for liver disease, concentrations of arsenic required to damage this organ are generally higher than found in the US water supply. The purpose of the current study was to test the hypothesis that arsenic (at subhepatotoxic doses) may also sensitize the liver to a second hepatotoxin. To test this hypothesis, the effect of chronic exposure to arsenic on liver damage caused by acute lipopolysaccharide (LPS) was determined in mice. Male C57Bl/6J mice (4-6 weeks) were exposed to arsenic (49 ppm as sodium arsenite in drinking water). After 7 months of exposure, animals were injected with LPS (10 mg/kg i.p.) and sacrificed 24 h later. Arsenic alone caused no overt hepatotoxicity, as determined by plasma enzymes and histology. In contrast, arsenic exposure dramatically enhanced liver damage caused by LPS, increasing the number and size of necroinflammatory foci. This effect of arsenic was coupled with increases in indices of oxidative stress (4-HNE adducts, depletion of GSH and methionine pools). The number of apoptotic (TUNEL) hepatocytes was similar in the LPS and arsenic/LPS groups. In contrast, arsenic pre-exposure blunted the increase in proliferating (PCNA) hepatocytes caused by LPS; this change in the balance between cell death and proliferation was coupled with a robust loss of liver weight in the arsenic/LPS compared to the LPS alone group. The impairment of proliferation after LPS caused by arsenic was also coupled with alterations in the expression of key mediators of cell cycle progression (p27, p21, CDK6 and Cyclin D1). Taken together, these results suggest that arsenic, at doses that are not overtly hepatotoxic per se, significantly enhances LPS-induced liver injury. These results further suggest that arsenic levels in the drinking water may be a risk modifier for the development of chronic liver diseases.",
Arsenic,628448,"Estrogen signaling in livers of male mice with hepatocellular carcinoma induced by exposure to arsenic in utero Abstract: BACKGROUND: Exposure of pregnant mice to inorganic arsenic induces a spectrum of tumors, including hepatocellular carcinoma (HCC), in their adult offspring similar to that induced by exposing adult mice to estrogenic compounds. To investigate whether arsenic exposure in utero causes altered estrogen signaling, we examined expression of estrogen receptor-alpha (ER-alpha), cyclin D1 (an estrogen-responsive hepatic oncogene), and several cytochrome P450 genes (with sexually dimorphic liver expression patterns) in livers from adult male mice with in utero arsenic-induced HCC. METHODS: Quantitative real-time reverse transcription-polymerase chain reaction was used to evaluate gene expression in livers of adult male mice that had (i.e., exposed mice; n = 8) or had not (i.e., control mice; n = 5) been exposed to arsenic in utero. DNA methylation status of portions of the ER-alpha and cyclin D1 gene promoters in liver tissue was measured using methylation-specific polymerase chain reaction. Statistical tests were two-sided. RESULTS: ER-alpha mRNA levels were 3.1-fold (95% confidence interval [CI] = 2.0-fold to 4.3-fold) higher in livers of exposed mice than in those of control mice, and cyclin D1 levels were 3.0-fold (95% CI = 1.7-fold to 4.3-fold) higher. Exposed mice showed a feminized expression pattern of several cytochrome P450 genes, expressing the female-dominant CYP2A4 (P =.017 versus control) and CYP2B9 (P<.001) genes at 8.7 and 10.5 times, respectively, the level in control mice and expressing the male-dominant CYP7B1 at approximately one-fourth the level in control mice(P =.0012). Exposed mice exhibited reduced (by approximately 90%) methylation of the ER-alpha gene promoter in liver DNA as compared with control mice; the cyclin D1 gene promoter was not methylated in either exposed or control mice. CONCLUSION: Altered estrogen signaling may play a role in induction of HCC by arsenic exposure in utero. Specifically, overexpression of ER-alpha, potentially through promoter region hypomethylation, in livers of such mice may be linked to the hepatocarcinogenicity of arsenic.",
Arsenic,2149348,Concentration of heavy metals on surface of filter materials and in backwash water Abstract: ,
Arsenic,2279067,"Bioaccumulation and biotransformation of arsenic compounds in Hediste diversicolor (Muller 1776) after exposure to spiked sediments Abstract: This study focused on the exposure of the common ragworm Hediste diversicolor (Müller 1776) to sediments enriched with different arsenic compounds, namely arsenate, dimethyl-arsinate, and arsenobetaine. Speciation analysis was carried out on both the spiked sediments and the exposed polychaetes in order to investigate H. diversicolor capability of arsenic bioaccumulation and biotransformation. Two levels of contamination (acute and moderate dose) were chosen for enriched sediments to investigate possible differences in the arsenic bioaccumulation patterns. The highest value of arsenic in tissues was reached after 15 days of exposure to dimethyl-arsinate (acute dose) spiked sediment (1,172?±?176 ?g/g). A significant increase was also obtained in worms exposed both to arsenate and arsenobetaine. Speciation analysis showed that trimethyl-arsine oxide was the predominant chemical form in tissues of H. diversicolor exposed to all the spiked sediments, confirming the importance of this intermediate in biological transformation of arsenic.",
Arsenic,20258,"Enhancement of viral transformation for evaluation of the carcinogenic or mutagenic potential of inorganic metal salts Abstract: Thirty-eight metal salts were tested for their capacity to enhance transformation of Syrian hamster embryo cells by a simian adenovirus, SA7. All of the metal salts with known carcinogenic potential in animals or mutagenic activity in microbial or mammalian cells increased the SA7 transformation frequency. Metals were classified into three groups according to the concentration necessary to produce significant enhancement. Those showing highest activity (positive at less than 0.05 mM) were the salts of antimony, arsenic, cadmium, chromium, and platinum. The second group (positive from 0.05 to 0.6 mM) included beryllium, cobalt, copper, lead, manganese, mercury, nickel, silver, thallium, and zinc. Iron salts were placed in a third group (only positive at concentrations greater than 0.9 mM). With the exception of ZnCl2 and ZnSO4, enhancement was demonstrated by both a relative increase in the viral transformation frequency and an absolute increase in the number of transformed foci among treated cells. The latter observation and the demonstration of enhancement in the absence of overt cell killing negate the possibility that enhancement resulted from the selection of transformation-sensitive cells.",
Arsenic,1016098,"Betel quid chewing elevates human exposure to arsenic, cadmium and lead Abstract: Several studies have reported increased skin lesions in betel quid (a mixture of Piper betel leaves, areca nut, tobacco/flavoured tobacco, lime) chewers compared to non-chewers, exposed to arsenic (As) contaminated drinking water in Bangladesh and India. The current study has determined As, cadmium (Cd) and lead (Pb) levels of betel quids and its components using inductively coupled plasma mass spectrometry (ICP-MS). The highest concentrations of As were found in slaked lime (4.56 mg kg(-1)) followed by Piper betel leaves (0.406 mg kg(-1)) and flavoured tobacco (zarda) (0.285 mg kg(-1)), with a mean concentrations of As in betel quids of 0.035 mg kg(-1) (SD 0.02 mg kg(-1)). Mean concentrations of Cd and Pb in ordinary quids were 0.028 (SD 0.07 mg kg(-1)) and 0.423 (SD 1.4 mg kg(-1)), respectively. We estimated that a daily intake of 6 betel quids could contribute 1.2, 1.9 and 8.5% of the provisional maximum tolerable daily intake (PMDTI) for As, Cd and Pb, respectively. Since betel quid chewing is most prevalent among women, our finding raises concern that women chewers - especially pregnant chewers - may be harming their health and that of their unborn babies through increased exposure to a mixture of toxic elements (As, Cd and Pb).",
Arsenic,1030858,"Low concentration of arsenite exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity Abstract: Epidemiological studies have associated arsenic exposure with many types of human cancers. Arsenic has also been shown to act as a co-carcinogen even at low concentrations. However, the precise mechanism of its co-carcinogenic action is unknown. Recent studies indicate that arsenic can interfere with DNA-repair processes. Poly(ADP-ribose) polymerase (PARP)-1 is a zinc-finger DNA-repair protein, which can promptly sense DNA strand breaks and initiate DNA-repair pathways. In the present study, we tested the hypothesis that low concentrations of arsenic could inhibit PAPR-1 activity and so exacerbate levels of ultraviolet radiation (UVR)-induced DNA strand breaks. HaCat cells were treated with arsenite and/or UVR, and then DNA strand breaks were assessed by comet assay. Low concentrations of arsenite (&lt;or=2 microM) alone did not induce significant DNA strand breaks, but greatly enhanced the DNA strand breaks induced by UVR. Further studies showed that 2 microM arsenite effectively inhibited PARP-1 activity. Zinc supplementation of arsenite-treated cells restored PARP-1 activity and significantly diminished the exacerbating effect of arsenite on UVR-induced DNA strand breaks. Importantly, neither arsenite treatment, nor zinc supplementation changed UVR-triggered reactive oxygen species (ROS) formation, suggesting that their effects upon UVR-induced DNA strand breaks are not through a direct free radical mechanism. Combination treatments of arsenite with PARP-1 inhibitor 3-aminobenzamide or PARP-1 siRNA demonstrate that PARP-1 is the target of arsenite. Together, these findings show that arsenite at low concentration exacerbates UVR-induced DNA strand breaks by inhibiting PARP-1 activity, which may represent an important mechanism underlying the co-carcinogenicity of arsenic.",
Arsenic,1326860,"Arsenite stabilizes HIF-1? protein through p85?-mediated up-regulation of inducible Hsp70 protein expression Abstract: Hypoxia-inducible factor-1? (HIF-1?) has been reported to regulate over 100 gene expressions in response to hypoxia and other stress conditions. In the present study, we found that arsenite could induce HIF-1? protein accumulation in both mouse epidermal Cl41 cells and mouse embryonic fibroblasts (MEFs). Knockout of p85?, a regulatory subunit of PI-3K, in MEFs (p85?(-/-)) dramatically decreased the arsenite-induced HIF-1? accumulation, indicating that p85? is crucial for arsenite effects on the stabilization of HIF-1? protein. Our further studies suggest that arsenite could induce inducible Hsp70 expression, and transfection of inducible Hsp70 into p85?(-/-) MEFs could restore HIF-1? protein accumulation. Moreover, the results using EMSA and Supershift assays indicate that p85? is crucial for arsenite-induced activation of the heat-shock transcription factor 1 (HSF-1), which is responsible for transcription of inducible Hsp70. Taken together, p85?-mediated HIF-1? stabilization upon arsenite exposure is specifically through HSF-1 activation and subsequent up-regulation of the inducible Hsp70 expression.",
Arsenic,626968,"Arsenic as an endocrine disruptor: Effects of arsenic on estrogen receptor-mediated gene expression in vivo and in cell culture Abstract: Arsenic (As) contamination of drinking water is considered a serious worldwide environmental health threat that is associated with increased disease risks including skin, lung, bladder and other cancers; type 2 diabetes; vascular and cardiovascular disease; reproductive and developmental effects; and neurological and cognitive effects. Increased health risks may occur at as low as 10-50 ppb, while biological effects have been observed in experimental animal and cell culture systems at much lower levels. We previously reported that As is a potent endocrine disruptor, altering gene regulation by the closely related glucocorticoid, mineralocorticoid, progesterone and androgen steroid receptors at concentrations as low as 0.01 µM ( 0.7 ppb). Very low doses enhanced hormone-mediated gene transcription whereas slightly higher but still non-cytotoxic doses were suppressive. We report here that As also disrupts the more distally related estrogen receptor (ER) both in vivo and in cell culture. At non-cytotoxic doses (1-50 µmol/kg arsenite) As strongly suppressed ER-dependent gene transcription of the 17ß-estradiol (E2)-inducible vitellogenin II gene in chick embryo liver in vivo. In cell culture, non-cytotoxic levels (0.25-3 µM, 20-225 ppb) of As significantly inhibited E2-mediated gene activation of an ER-regulated reporter gene and the native ER-regulated GREB1 gene in human breast cancer MCF-7 cells. While the effects of As on ER-dependent gene regulation were generally similar to As effects on the other steroid receptors, there were specific differences, particularly the lack of significant enhancement at the lowest doses, that may provide insights into possible mechanisms.",
Arsenic,2347583,"Bioaccessibility of metals in soils: Comparison between chemical extractions and in vitro tests Abstract: It is well-known that the total metal content in soils is not a good indicator of their harmful effects, leading to an overestimation of risks. Toxicological and environmental hazards depend on the chemical species and on its bioavailability to target organisms. Because a good estimation of bioavailability is difficult, a good compromise is to assess bioaccessibility, defined as the maximum amount of a pollutant which is potentially absorbable by a target organism. This study presents a comparison of different strategies to measure metal bioaccessibility in soils. Three procedures were applied to real soil samples with different levels of metal contamination: pseudo-total metal attack, selective sequential extractions and in vitro tests (deliberately developed to simulate human or mammals digestion). Considering the first step of the selective extraction procedure, which can provide the bioaccessible fraction for deposit-feeder organisms, data obtained for each metal were lower than those obtained from in vitro tests. Therefore, it is possible to highlight that this extraction tends to underestimate metal bioaccessibility in soils for humans, while in vitro tests certainly will overestimate bioaccessibility for organisms as invertebrates. If the sum of first and second step of sequential procedure is considered, results are quite similar to those obtained from in vitro tests, but this kind of procedure would require two days of work rather than a few hours required to perform an in vitro test. Results highlight the diversity among the differently defined bioaccessible fractions and the need to apply the most suitable procedure depending on the target organism.",
Arsenic,1356566,"SOME NEW ASPECTS OF MITOTIC POISONING Abstract: Several aspects of mitotic poisoning are reviewed. The mechanism of nuclear destruction by pycnosis is discussed. Pycnosis is the alteration of the lymphocyte consisting of a sudden agglomeration of all chromatin structures in small spherical masses. Swelling of the cytoplasm, alterations of the nuclear membrane, and accumulation of the thymonucleic-acid on the nuclear membrane are evident in nuclear degeneration. The effects of carbamates and cyanates such as ethylcarbamate (51796), ethylphenylcarbamate (101995), sodium-cyanate (917613), and potassium-thiocyanate (333200) on cellular division are examined. Special consideration is also given to the nitrogen mustards such as bis(beta-chloroethyl)amine (334225). The possible actions of arsenic (7440382) derivatives and dimercaptopropanol (59529) are also mentioned. The relationship between mitotic poisons and the different periods of the cellular cycle is discussed. Radiation sensitivity is also examined. When a cell is irradiated during the period preceding prophase it becomes incapable of normal mitosis and breaks down. Several recent theories on the mechanism of mitotic poisoning are presented. One hypothesis suggests that various mitotic poisons act as enzyme inhibitors, preventing either the onset of prophase or the polarization of the spindle. The author concludes that the action of mitotic poisons on various enzyme systems may further our knowledge of the cytochemical processes of cellular division.",
Arsenic,628000,"Sulforaphane, an activator of Nrf2, suppresses cellular accumulation of arsenic and its cytotoxicity in primary mouse hepatocytes Abstract: Sulforaphane (SFN) is an activator of the transcription factor Nrf2, which plays a critical role in metabolism and excretion of xenobiotics. Exposure of primary mouse hepatocytes to SFN resulted in activation of Nrf2 and significant elevation of protein expressions responsible for excretion of arsenic into extracellular space. Pretreatment with SFN 24 h prior to arsenite exposure reduced not only arsenic accumulation in the cells but also cellular toxicity of this metalloid. Therefore, our findings indicate a potential function of SFN in reducing cellular arsenic levels, thereby diminishing arsenic toxicity.",
Arsenic,1379381,"Gallium Arsenide Exposure Upregulates Inflammatory Cytokine Expression Abstract: The semiconductor, gallium arsenide (GaAs), is classified as an immunotoxicant and a carcinogen. We previously showed that GaAs in vivo induces several phenotypic changes in macrophages located at the exposure site, indicative of an activated state. To discern primary consequences, macrophage cell lines and murine peritoneal macrophages were exposed to the chemical in vitro. In culture, GaAs augmented invariant chain protein expression, and proteolytic activities and mRNA expression of cathepsins L and B. However, GaAs did not alter cell surface expression of major histocompatibility complex class II molecules on the macrophages, nor influence their ability to stimulate antigen-specific helper T cell s to respond to intact antigens that require processing. In vitro GaAs exposure did not completely mirror in vivo exposure, suggesting that other cells or factors may be involved. We examined the role of cytokines in GaAs-mediated macrophage activation. Blood monocytes were rapidly recruited to the exposure site, and the chemokine MCP-1 was present in the sera of exposed mice. The mRNA of seventeen chemokines and inflammatory cytokines were upregulated, while transcripts of three inhibitory cytokines diminished. Administration of latex beads caused less cytokine induction than GaAs, indicating that changes in mRNA levels could not be attributed to phagocytosis alone. Four cytokine proteins examined were mainly produced by myeloid cells. In vivo GaAs exposure alters cytokine gene expression which may lead to an inflammatory reaction and contribute to pathological tissue damage.",
Arsenic,1508575,"Evaluation of metal impurities in foods preserved with sodium lactate Abstract: The public is being bombarded by the media almost dailywith real and potential food health concerns leadingto a public sentiment that questions the vulnerability and quality of our food. Sodium lactate is a food-grade product that in recent years has been used in bioremediation to stimulate microbial growth and contaminant breakdown processes. In previous work, impurities including arsenic and chromium were discovered to be present in the sodium lactate concentrate. The study described in this article was performed to determine whether arsenic and chromium were at detectable levels, posing a potential concern in food products preserved with sodium lactate available to the general public. A pilot sampling of three sodium-lactate-preserved food products was obtained from a local market and used to determine the commercial laboratory's detection and reporting limits for arsenic and chromium for these food products. Once these limits were established, a random sampling and analyses of 17 food products was performed. Arsenic was not reported above the detection limits in either the pilot or subsequent study, but chromium was detected at concentrations up to 0.30 parts per million in a pilot test sample and lower concentrations in the subsequent study. This study suggests that the sodium lactate in the sampled products was diluted enough for the arsenic concentration to be below the laboratory detection limit. Chromium was detected and may be an unaccounted source of chromium in diets of vulnerable populations.",
Arsenic,1597367,"Is an assessment factor of 10 appropriate to account for the variation in chemical toxicity to freshwater ectotherms under different thermal conditions? Abstract: Ecotoxicity tests are often conducted following standard methods, and thus carried out at a fixed water temperature under controlled laboratory conditions. Yet, toxicity of a chemical contaminant may vary in a temperature-dependent manner, depending on the physiology of the test organism and physicochemical properties of the chemical. Although an assessment factor of 10 (AF10) is commonly adopted to account for variability in toxicity data related to temperature in the development of water quality guidelines and/or ecological risk assessment, no one has ever rigorously assessed the appropriateness of AF10 to account for potential variation in temperature-dependent chemical toxicity to aquatic organisms. This study, therefore, aims to address this issue through a meta-analysis by comparing median lethal concentration data for nine chemicals (cadmium, copper, nickel, lead, silver, zinc, arsenic, selenium and DDT) on a range of freshwater ectothermic animal species at different temperatures, and to assess whether AF10 is under- or over-protective for tropical and temperate freshwater ecosystems. Our results reveal varying extents of interaction between temperature and different chemicals on organisms and the complexity of these interactions. Applying AF10 sufficiently protects 90 % of the animal species tested over a range of temperatures for cadmium, copper, nickel, silver, zinc and DDT in the tropics, but it is insufficient to adequately encompass a larger temperature variation for most studied chemicals in temperate regions. It is therefore important to set specific AFs for different climatic zones in order to achieve the desired level of ecosystem protection.",
Arsenic,628389,"Health effects of exposure to natural arsenic in groundwater and coal in China: An overview of occurrence Abstract: Between 2001 and 2005, 21,155 of 445,638 wells in 20,517 villages in 292 counties in 16 provinces from China, or 5% of wells, were found to contain > 50 microg/L arsenic (As) by field testing with the Merck As kit. We achieved quality assurance of analysis of at least 10% of the wells containing > 50 microg/L As using hydride generation atomic fluorescence spectrometry and silver dithiodicarbomate spectrometry. Our best estimate of the population exposed to > 50 microg/L As in drinking water was 582,769. This is probably an underestimate for China because of the limited area surveyed. In a survey of 135,492 individuals in eight provinces, we used the National Diagnosis Standard for Endemic Arsenicosis and identified 10,096 cases of arsenicosis with various degrees of skin lesions. The arsenicosis occurrence rate of 7.5% is likely an overestimate, because the survey focused more on known and suspected endemic areas of arsenicosis. The occurrence of arsenicosis correlates positively with the percentage of wells containing > 50 microg/L As, or at a ratio of 1 to 5%. Based on both the amount of As in well water and the rate of occurrence of arsenicosis, Shanxi province, Inner Mongolia autonomous region, and Jilin province are the top three areas in China as of 2005 for exposure to endemic As from drinking water. Our survey also identified exposure to high levels of As from wells in several provinces and from the indoor burning of coal containing high levels of As in Shaanxi province. These areas, however, have not had any reports of previous arsenicosis endemics. In the endemic areas, the average rate of occurrence of arsenicosis at advanced stages was 1.2%, possibly because of a long exposure time of > 20 years; the rate of occurrence increased to 2.7% when we included a high dose of As exposure from the indoor burning of coal. Mitigation to reduce As exposure remains a challenge in rural China.",
Arsenic,1339164,"Pannonibacter indica sp. nov., a highly arsenate-tolerant bacterium isolated from a hot spring in India Abstract: A novel aerobic bacterium, strain HT23(T), able to grow on 500 mM sodium arsenate was isolated from a hot-spring sediment sample collected from Athamallik, Orissa, India. Cells of this isolate were Gram negative. Heterotrophic growth was observed at pH 6.0-11.0 and 20-45 °C. Optimum growth was observed at 37 °C and pH 7.0-10.0. The major polar lipids are diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl choline and phosphatidyl monomethyl ethanolamine. The major isoprenoid quinone was Q-10. 16S rRNA gene sequence analysis indicated that the bacterium clustered with the genus Pannonibacter and showed 98.9 % similarity with Pannonibacter phragmitetus C6-19(T) (DSM 14782(T)) and 98 % with the P. phragmitetus group B and P. phragmitetus group E strains. Levels of DNA-DNA relatedness between the strain HT23(T) and P. phragmitetus C6-19(T) (DSM 14782(T)) and other strains of P. phragmitetus group B and group E strains were below 55 %. On the basis of phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequence analysis and DNA-DNA hybridization data, strain HT23(T) is considered to represent a novel species of the genus Pannonibacter, for which the name Pannonibacter indica sp. nov. is proposed. The type strain is HT23(T) (=JCM 16851(T) = DSM 23407(T) = LMG 25769(T)).",
Arsenic,1597327,"Can fatty acid and mineral compositions of sturgeon eggs distinguish between farm-raised versus wild white (Acipenser transmontanus) sturgeon origins in California? Preliminary report Abstract: The objective was to investigate the potential of using fatty acid and mineral compositions of sturgeon eggs to distinguish their source, either farm-raised or wild fish. Trafficking of illegally obtained wild white sturgeon eggs is a major concern to the California Department of Fish and Game, but there is no forensic method to separate wild and farm-raised white sturgeon eggs. The extension of these findings in future work will be to use the fatty acid and mineral compositions as forensic indicators of caviar produced legally from farm raised sturgeon compared with illegal caviar produced from sturgeon poached from the wild. Samples (10) of sturgeon eggs were collected from a commercial aquaculture facility in the Sacramento Valley. Eggs from wild sturgeon (9) were obtained primarily from confiscations of illegally caught sturgeon by fish and game law enforcement personnel. The total lipid content of sturgeon eggs was analyzed for fatty acid composition. The most notable difference was the higher concentration (P&lt;0.001) of C18:2n6 in farm raised eggs (6.5mg/100g total lipid) than wild eggs (0.6mg/100g total lipid) while other differences between fatty acids were smaller. Eicosapentaenoic acid (C20:5n3) was higher (P&lt;0.02) in farm-raised (5.56mg/100g) than wild (4.49mg/100g). Docosahexaenoic acid (C22:6n3), C18:1 cis 9&amp;10, and C20:4n6 were not different for origin of the eggs. Concentration of selenium was markedly higher (P&lt;0.001) in eggs from wild sturgeon (10.0mg/kg dry weight) than farm-raised sturgeon (2.7mg/kg dry weight). Concentrations of iron, zinc, copper, phosphorus, sulfur, calcium, and potassium did not differ between farm-raised and wild eggs. Arsenic concentration in wild eggs was 3.3mg/kg dry weight whereas arsenic was not detected in the farm-raised eggs. Fatty acid and mineral compositions of eggs differed significantly between farm-raised and wild sturgeon and these should be investigated further as biological markers for forensic identification of caviar origin.",
Arsenic,1337535,"Apo A5 -1131T/C, FgB -455G/A, -148C/T, and CETP TaqIB gene polymorphisms and coronary artery disease in the Chinese population: a meta-analysis of 15,055 subjects Abstract: The Apolipoprotein A5 (APO A5) -1131T/C, fibrinogen ? (FgB) -455G/A, -148C/T, and cholesteryl ester transfer protein (CETP) TaqIB gene polymorphisms have been indicated to be associated with the coronary artery disease (CAD) risk, but the individual study results are still inconsistent. To explore the relationship between APO A5 -1131T/C, FgB -455G/A, -148C/T, and CETP TaqIB gene polymorphisms and CAD in the Chinese population, the current meta-analysis involving 15,055 subjects from 40 individual studies was conducted. The pooled odds ratio (OR) for the association between APO A5 -1131T/C, FgB -455G/A, -148C/T, and CETP TaqIB gene polymorphisms and CAD and its corresponding 95 % confidence interval (95 % CI) were evaluated by random or fixed effect model. A significant association between APO A5 -1131T/C gene polymorphism and CAD in the Chinese population was found under an allelic (OR: 1.33, 95 % CI: 1.22-1.44, P &lt; 0.00001), recessive (OR: 1.67, 95 % CI: 1.25-2.25, P = 0.0006), dominant (OR: 0.820, 95 % CI: 0.767-0.876, P = 1.0 × 10(-10)), homozygous (OR: 2.36, 95 % CI: 1.55-3.58, P &lt; 0.0001) and heterozygous genetic models (OR: 1.136, 95 % CI:1.075-1.200, P = 1.0 × 10(-10)). A significant association between FgB -455G/A gene polymorphism and CAD was also detected in the Chinese population under an allelic (OR: 1.50, 95 % CI: 1.25-1.81, P &lt; 0.0001), dominant (OR: 0.864, 95 % CI: 0.819-0.912, P = 1.0 × 10(-10)), homozygous (OR: 1.616, 95 % CI: 1.213-2.152, P = 0.001) and heterozygous genetic models (OR: 1.245, 95 % CI:1.138-1.361, P = 1.0 × 10(-10)). No significant association was found between them under a recessive genetic model (OR: 1.124, 95 % CI: 0.844-1.497, P = 0.424). A significant association was also found between FgB -148C/T gene polymorphism and CAD in the Chinese population under an allelic (OR: 1.34, 95 % CI: 1.06-1.71, P = 0.02), recessive (OR: 1. 65, 95 % CI: 1.02-2.69, P = 0.04), dominant (OR: 0.924, 95 % CI: 0.872-0.978, P = 0.007) and homozygous genetic models (OR: 0.968, 95 % CI: 0.942-0.995, P = 0.018). No significant association was found between them under a heterozygous genetic model (OR: 0.979, 95 % CI: 0.937-1.023, P = 0.342). In the whole Chinese population, no significant association between the CETP TaqIB gene polymorphism and CAD was found under an allelic (OR: 1.17, 95 % CI: 0.94-1.45, P = 0.15), dominant (OR: 1.46, 95 % CI: 0.80-2.67, P = 0.22) or recessive genetic models (OR: 0.68, 95 % CI: 0.32-1.44, P = 0.31). However, in the subgroup analysis stratified by ethnicity, there was a significant association between them under an allelic (OR: 1.27, 95 % CI: 1.07-1.52, P = 0.007) and dominant genetic model (OR: 2.04, 95 % CI: 1.49-2.79, P &lt; 0.00001) in the Han subgroup. In the Chinese population, the APO A5 -1131T/C and FgB -455G/A, -148C/T gene polymorphisms were implied to be associated with CAD susceptibility. The APO A5 -1131C, FgB -455A, and -148T alleles might confer susceptibility to CAD. CETP TaqIB gene polymorphism was suggested to be associated with CAD susceptibility in the Chinese Han population. Carriers with B1 allele of CETP TaqIB gene might be predisposed to CAD in the Chinese Han population.",
Arsenic,1797753,"III-V nanocrystals capped with molecular metal chalcogenide ligands: High electron mobility and ambipolar photoresponse Abstract: In this work, we synthesized InP and InAs nanocrystals (NCs) capped with different inorganic ligands, including various molecular metal chalcogenide complexes (MCCs) and chalcogenide ions. We found that MCCs and chalcogenide ions can quantitatively displace organic ligands from the surface of III-V NCs and serve as the inorganic capping groups for III-V NC surfaces. These inorganic ligands stabilize colloidal solutions of InP and InAs NCs in polar solvents and greatly facilitate charge transport between individual NCs. Charge transport studies revealed high electron mobility in the films of MCC-capped InP and InAs NCs. For example, we found that bridging InAs NCs with Cu(7)S(4)(-) MCC ligands can lead to very high electron mobility exceeding 15 cm(2)/(V s). In addition, we observed unprecedented ambipolar (positive/negative) photoresponse of MCC-capped InAs NC solids that changed sign depending on the ligand chemistry, illumination wavelength, and doping of the NC solid. For example, the sign of photoconductance of InAs NCs capped with Cu(7)S(4)(-) or Sn(2)S(6)(4-) ions converted from positive at 0.80 and 0.95 eV to negative at 1.27 and 1.91 eV. We propose an explanation of this unusually complex photoconductivity of InAs NC solids.",
Arsenic,2347598,"Telecare collaborative management of chronic pain in primary care: a randomized clinical trial Abstract: <strong>IMPORTANCE: </strong>Chronic musculoskeletal pain is among the most prevalent, costly, and disabling medical disorders. However, few clinical trials have examined interventions to improve chronic pain in primary care.<br /><br /><strong>OBJECTIVE: </strong>To determine the effectiveness of a telecare intervention for chronic pain.<br /><br /><strong>DESIGN, SETTING, AND PARTICIPANTS: </strong>The Stepped Care to Optimize Pain Care Effectiveness (SCOPE) study was a randomized trial comparing a telephone-delivered collaborative care management intervention vs usual care in 250 patients with chronic (?3 months) musculoskeletal pain of at least moderate intensity (Brief Pain Inventory [BPI] score ?5). Patients were enrolled from 5 primary care clinics in a single Veterans Affairs medical center from June 2010 through May 2012, with 12-month follow-up completed by June 2013.<br /><br /><strong>INTERVENTIONS: </strong>Patients were randomized either to an intervention group (n?=?124) or to a usual care group whose members received all pain care as usual from their primary care physicians (n?=?126). The intervention group received 12 months of telecare management that coupled automated symptom monitoring with an algorithm-guided stepped care approach to optimizing analgesics.<br /><br /><strong>MAIN OUTCOMES AND MEASURES: </strong>Primary outcome was the BPI total score, which ranges from 0 (&quot;no pain&quot;) to 10 (&quot;pain as bad as you can imagine&quot;) and for which a 1-point change is considered clinically important. Secondary pain outcomes included BPI interference and severity, global pain improvement, treatment satisfaction, and use of opioids and other analgesics.<br /><br /><strong>RESULTS: </strong>Overall, mean (SD) baseline BPI scores in the intervention and control groups were 5.31 (1.81) and 5.12 (1.80), respectively. Compared with usual care, the intervention group had a 1.02-point lower (95% CI, -1.58 to -0.47) BPI score at 12 months (3.57 vs 4.59). Patients in the intervention group were nearly twice as likely to report at least a 30% improvement in their pain score by 12 months (51.7% vs 27.1%; relative risk, 1.9 [95% CI, 1.4 to 2.7]), with a number needed to treat of 4.1 (95% CI, 3.0 to 6.4) for a 30% improvement. Secondary pain outcomes also improved. Few patients in either group required opioid initiation or dose escalation.<br /><br /><strong>CONCLUSIONS AND RELEVANCE: </strong>Telecare collaborative management increased the proportion of primary care patients with improved chronic musculoskeletal pain. This was accomplished by optimizing nonopioid analgesic medications using a stepped care algorithm and monitoring.<br /><br /><strong>TRIAL REGISTRATION: </strong>clinicaltrials.gov Identifier: NCT00926588.",
Arsenic,1027548,"Comparative functional genomic analysis identifies distinct and overlapping sets of genes required for resistance to monomethylarsonous acid (MMAIII) and arsenite (AsIII) in yeast Abstract: Arsenic is a human toxin and carcinogen commonly found as a contaminant in drinking water. Arsenite (As(III)) is the most toxic inorganic form, but recent evidence indicates that the metabolite monomethylarsonous acid (MMA(III)) is even more toxic. We have used a chemical genomics approach to identify the genes that modulate the cellular toxicity of MMA(III) and As(III) in the yeast Saccharomyces cerevisiae. Functional profiling using homozygous deletion mutants provided evidence of the requirement of highly conserved biological processes in the response against both arsenicals including tubulin folding, DNA double-strand break repair, and chromatin modification. At the equitoxic doses of 150 microM MMA(III) and 300 microM As(III), genes related to glutathione metabolism were essential only for resistance to the former, suggesting a higher potency of MMA(III) to disrupt glutathione metabolism than As(III). Treatments with MMA(III) induced a significant increase in glutathione levels in the wild-type strain, which correlated to the requirement of genes from the sulfur and methionine metabolic pathways and was consistent with the induction of oxidative stress. Based on the relative sensitivity of deletion strains deficient in GSH metabolism and tubulin folding processes, oxidative stress appeared to be the primary mechanism of MMA(III) toxicity whereas secondary to tubulin disruption in the case of As(III). Many of the identified yeast genes have orthologs in humans that could potentially modulate arsenic toxicity in a similar manner as their yeast counterparts.",
Arsenic,735053,"Arsenic transformations and biomarkers in meadow voles (Microtus pennsylvanicus) living on an abandoned gold mine site in Montague, Nova Scotia, Canada Abstract: Arsenic is one of the most widely encountered environmental contaminants because of a number of anthropogenic sources; in Canada the main anthropogenic release of arsenic is from mine tailings ponds. The present study is part of a series of studies to measure chemical and biological effects of exposure for meadow voles (Microtus pennsylvanicus) living on arsenic contaminated sites. Two additional objectives were addressed in the present study: the effect of higher arsenic concentrations compared with previous studies, and the comparison of chemical speciation and biological effects. To obtain the higher environmental concentrations, specimens were collected from a former gold mining site in Montague, NS that contains highly elevated concentrations of arsenic in soils and plants. Meadow voles were collected and their tissues were analyzed for total arsenic to measure uptake, and arsenic speciation to examine the chemical effects of the high arsenic exposure. In addition to the arsenic analysis, a biomonitoring study was undertaken to examine the sub-cellular effects in meadow voles resulting from the elevated arsenic exposure. Meadow voles living on the contaminated site had substantially higher concentrations of total arsenic than animals from the background (reference) location. The extractable arsenic in internal tissues was present mainly as monomethylarsonic acid (up to 14% of total arsenic). A statistically significant relationship was observed between the reduction of glutathione in vole livers and the increase in liver arsenic concentrations, and micronucleated monochromatic red blood cells were also significantly elevated in voles from the arsenic contaminated site. This is one of the few field studies where sub-cellular effects were observed, and the first to show a co-existence of such effects with relatively high proportions of monomethylarsonic acid in voles living near mine tailings.",
Arsenic,1337631,"Arsenic exposure, diabetes prevalence, and diabetes control in the strong heart study Abstract: This study evaluated the association of arsenic exposure, as measured in urine, with diabetes prevalence, glycated hemoglobin, and insulin resistance in American Indian adults from Arizona, Oklahoma, and North and South Dakota (1989-1991). We studied 3,925 men and women 45-74 years of age with available urine arsenic measures. Diabetes was defined as a fasting glucose level of 126 mg/dL or higher, a 2-hour glucose level of 200 mg/dL or higher, a hemoglobin A1c (HbA1c) of 6.5% or higher, or diabetes treatment. Median urine arsenic concentration was 14.1 µg/L (interquartile range, 7.9-24.2). Diabetes prevalence was 49.4%. After adjustment for sociodemographic factors, diabetes risk factors, and urine creatinine, the prevalence ratio of diabetes comparing the 75th versus 25th percentiles of total arsenic concentrations was 1.14 (95% confidence interval: 1.08, 1.21). The association between arsenic and diabetes was restricted to participants with poor diabetes control (HbA1c ?8%). Arsenic was positively associated with HbA1c levels in participants with diabetes. Arsenic was not associated with HbA1c or with insulin resistance (assessed by homeostatic model assessment to quantify insulin resistance) in participants without diabetes. Urine arsenic was associated with diabetes control in a population from rural communities in the United States with a high burden of diabetes. Prospective studies that evaluate the direction of the relation between poor diabetes control and arsenic exposure are needed.",
Arsenic,1348490,"Determination of lead and copper in chewing gum samples by electrothermal-flame atomic absorption spectrometry using various chemical modifiers and arsenic by hydride generation Abstract: Lead and copper in chewing gum samples were determined by electrothermal atomic absorption spectrometry (ETAAS) with Zeeman background correction using various chemical modifiers and by flame atomic absorption spectrometry (FAAS) using 2% m/v ammonium pyrrolidine dithiocarbamate (APDC) complexing reagent in methyl isobuthyl keton (MIBK). Arsenic in samples was determined by hydride generation atomic absorption spectrometry (HGAAS). In order to decrease the interferences in sample matrix by ETAAS, Pd, Pt, W, Mo, Mg, PO43?, their mixtures and W+Pd+tartaric acid (TA) have been tested as matrix modifiers in sample solutions. Modifiers have been compared in terms of pyrolysis temperature, atomization and background profiles of analytes. W+Pd+TA modifier mixture found as preferable was used for the determination of analytes by ETAAS. The reliability of the procedures was verified by analyzing several certified reference materials (CRMs). Detection limits of Pb and Cu determined by ETAAS and As determined by HGAAS were 1.2, 0.8 and 3.0 ?g l?1 for Pb, Cu and As, respectively.",
Arsenic,1025323,"Arsenic and chromium in canned and non-canned beverages in Nigeria: A potential public health concern Abstract: Numerous studies have described environmental exposure of humans to heavy metals in African populations. Little is known about the exposure to heavy metal toxins from processed or unprocessed foods consumed in Africa, and no data exists on the food concentrations of arsenic and chromium, which are potential carcinogens and systemic toxicants. This study determined the concentrations of arsenic and chromium in beverages and fruit drinks commonly sold in Nigeria. Fifty samples of commonly consumed canned and non-canned beverages (imported and locally manufactured) purchased in Nigeria were digested in nitric acid and analyzed by atomic absorption spectrophotometry (AAS). 33.3% of the canned beverages had arsenic levels that exceeded the maximum contaminant level (MCL) of 0.01 mg/L set by U.S. EPA while 55.2% of non-canned beverages had their arsenic levels exceeding the MCL. The arsenic concentrations ranged from 0.003 to 0.161 mg/L for the canned and 0.002 to 0.261 mg/l for the non-canned beverages. Whereas 68.9% of the non-canned beverages showed chromium levels that exceeded the US EPA's MCL of 0.10 mg/L, 76.2% of the canned beverages had chromium levels that were greater than the MCL. The concentration range of total chromium in the canned beverages was 0.04 to 0.59 mg/L and 0.01 to 0.55 mg/L for the non-canned beverages. The sources of arsenic and chromium in the commercially available beverages are unclear and merit further investigation. This preliminary study highlights the need to study the toxicological implications of chronic low-level exposure to heavy metals from African markets.",
Arsenic,1372288,"DNA strand breaks in mammalian tissues induced by methylarsenics Abstract: DNA damage induced by administration of dimethylarsinic acid (DMAA) to rats and mice was investigated. At 12 h after administration of DMAA, DNA single-strand breaks were induced markedly in lung. The majority of dimethylarsine, one of the main metabolites, in the expired air was excreted within 6-18 h after administration of DMAA to rats. In vitro experiments using nuclei isolated from lung of mice indicated that DNA strand breaks were caused by dimethylarsine. Furthermore, the strand breaks after exposure to dimethylarsine were reduced in the presence of catalase and/or superoxide dismutase. These results strongly suggest that the strand breaks are induced not by dimethylarsine itself but by active oxygen, e.g., O2- and .OH, produced both by dimethylarsine and molecular oxygen. When DNA was exposed to dimethylarsine, thiobarbituric acid (TBA)-reactive intermediates and cis-thymine glycol were produced. Dimethylarsine appears to induce DNA damage by the mechanism similar to the damage produced by ionizing radiation.",
Arsenic,628543,"Arsenic-induced gene expression changes in the neural tube of folate transport defective mouse embryos Abstract: Arsenic injected intraperitoneally (i.p.) during early organogenesis to small pregnant laboratory rodents (mouse, rat, and hamster) induces several congenital defects in the progeny. Among those abnormalities consistently and predominantly observed are exencephaly and encephalocele. These severe defects of the central nervous system originate from a corrupted process of neurulation and are better known as neural tube defects (NTDs). In order to understand the mechanism of arsenate-induced NTDs, we designed studies in which highly sensitive Folr2 nullizygous mice were injected intraperitoneally with sodium arsenate at the beginning of the neural tube formation process. This specific knockout mouse and the arsenic exposure conditions were chosen as they were known to provide a high incidence of exencephaly in exposed embryos. We have applied gene expression technology to the anterior neural tube. This allowed us to study arsenic-induced changes in patterns of gene expression that may contribute to the development of neural tube defects in these mice. Using extensive data analysis approaches including hierarchical clustering and gene ontology analysis, we identified several candidate genes as well as important ontology groups that may be responsible for arsenic's teratogenicity. Changes in the expression of several genes in response to arsenic treatment in our model had previously been demonstrated by other investigators to also induce NTDs in murine model systems. These include: engrailed 1 (En-1), platelet derived growth factor receptor alpha (Pdgfralpha) and ephrinA7 (EphA7). We also found several gene ontology groups that could be implicated in arsenic's underlying teratogenicity: morphogenesis, oxidative phosporylation, redox response, and regulation of I-kappaB kinase/NF-kappaB cascade. Additionally, we revealed new target genes which may be responsible for arsenic disrupted oxidative phosphorylation.",
Arsenic,1255526,"An investigation of arsenic contamination in Peninsular Malaysia based on Centella asiatica and soil samples Abstract: The first objective of this study was to provide data of arsenic (As) levels in Peninsular Malaysia based on soil samples and accumulation of As in Centella asiatica collected from 12 sampling sites in Peninsular Malaysia. The second objective was to assess the accumulation of As in transplanted C. asiatica between control and semi-polluted or polluted sites. Four sites were selected which were UPM (clean site), Balakong (semi-polluted site), Seri Kembangan (semi-polluted site) and Juru (polluted site). The As concentrations of plant and soil samples were determined by Instrumental Neutron Activation Analysis. The As levels ranged from 9.38 to 57.05 ?g/g dw in soils, 0.21 to 4.33 ?g/g dw in leaves, 0.18 to 1.83 ?g/g dw in stems and 1.32-20.76 ?g/g dw in roots. All sampling sites had As levels exceeding the CCME guideline (12 ?g/g dw) except for Kelantan, P. Pauh, and Senawang with P. Klang having the highest As in soil (57.05 ?g/g dw). In C. asiatica, As accumulation was highest in roots followed by leaves and stems. When the As level in soils were higher, the uptake of As in plants would also be increased. After the transplantation of plants to semi-polluted and polluted sites for 3 weeks, all concentration factors were greater than 50 % of the initial As level. The elimination factor was around 39 % when the plants were transplanted back to the clean sites for 3 weeks. The findings of the present study indicated that the leaves, stems and roots of C. asiatica are ideal biomonitors of As contamination. The present data results the most comprehensive data obtained on As levels in Malaysia.",
Arsenic,2278613,"Speciated arsenic concentrations, exposure, and associated health risks for rice and bulgur Abstract: Arsenic species were determined in rice and bulgur samples that were collected from 50 participants who also supplied exposure related information through a questionnaire survey. Speciation analysis was conducted using an HPLC-ICP-MS system. Ingestion exposure to arsenic and associated health risks were assessed by combining the concentration and questionnaire data both for individual participants and the subject population. Inorganic arsenic dominated both in rice and bulgur but concentrations were about an order of magnitude higher in rice (160±38ng/g) than in bulgur. Because participants also consumed more rice than bulgur, exposures were significantly higher for rice resulting in carcinogenic risks above acceptable level for 53% and 93% of the participants when the in-effect and the proposed potencies were used, respectively, compared to 0% and 5% for bulgur. An inorganic arsenic standard for rice would be useful to lower the risks while public awareness about the relation between excessive rice consumption and health risks is built, and bulgur consumption is promoted.",
Arsenic,1326793,"Short dysfunctional telomeres impair the repair of arsenite-induced oxidative damage in mouse cells Abstract: Telomeres and telomerase appear to participate in the repair of broken DNA ends produced by oxidative damage. Arsenite is an environmental contaminant and a potent human carcinogen, which induces oxidative stress on cells via the generation of reactive oxygen species affecting cell viability and chromosome stability. It promotes telomere attrition and reduces cell survival by apoptosis. In this study, we used mouse embryonic fibroblasts (MEFs) from mice lacking telomerase RNA component (mTERC(-/-) mice) with long (early passage or EP) and short (late passage or LP) telomeres to investigate the extent of oxidative damage by comparing the differences in DNA damage, chromosome instability, and cell survival at 24 and 48 h of exposure to sodium arsenite (As3+; NaAsO2). There was significantly high level of DNA damage in mTERC(-/-) cells with short telomeres as determined by alkaline comet assay. Consistent with elevated DNA damage, increased micronuclei (MN) induction reflecting gross genomic instability was also observed. Fluorescence in situ hybridization (FISH) analysis revealed that increasing doses of arsenite augmented the chromosome aberrations, which contributes to genomic instability leading to possibly apoptotic cell death and cell cycle arrest. Microarray analysis has revealed that As3+ treatment altered the expression of 456 genes of which 20% of them have known functions in cell cycle and DNA damage signaling and response, cell growth, and/or maintenance. Results from our studies imply that short dysfunctional telomeres impair the repair of oxidative damage caused by arsenite. The results will have implications in risk estimation as well as cancer chemotherapy.",
Arsenic,1519182,"Influence of pH and alkalinity in the sorption of As and heavy metals by Fe oxi-hydroxides in skarn-type Pb-Zn-Ag tailings Abstract: Processes of heavy metals and arsenic sorption onto Fe oxyhydroxides derived from leachates of Pb-Zn-Ag skarn-type mineralization, were investigated through humidity cell experiments and hydrogeo-chemical modeling. Humidity cell tests and leaching column experiments were conducted to determine the influence of pH and the concentration of dissolved metals and arsenic in the leacheates. The leachates had pH values near neutrality (pH = 7) and a relatively low concentration of toxic metals in solution, despite the evident dissolution of sulfide minerals. The oxidation ofpyrrhotite and the acid-consuming dissolution reaction of calcite catalyze the precipitation of ferryhidrite (Fe oxyhydroxide), which acts as adsorbing surfaces for metals and metalloids in solution (As, Cu, Pb and Zn). The sorption by ferryhydrite in ore deposits of this type represents one of the controlling mechanisms of the concentrations of As and heavy metals under pH conditions between 6 and 8 (near neutrality).",
Arsenic,628593,"Association of arsenic exposure during pregnancy with fetal loss and infant death: A cohort study in Bangladesh Abstract: The authors evaluated the effect of arsenic exposure on fetal and infant survival in a cohort of 29,134 pregnancies identified by the health and demographic surveillance system in Matlab, Bangladesh, in 1991-2000. Arsenic exposure, reflected by drinking water history and analysis of arsenic concentrations in tube-well water used by women during pregnancy, was assessed in a separate survey conducted in 2002-2003. Data on vital events, including pregnancy outcome and infant mortality, were collected by monthly surveillance at the household level. The risk of fetal loss and infant death in relation to arsenic exposure was estimated by a Cox proportional hazards model. Drinking tube-well water with more than 50 microg of arsenic per liter during pregnancy significantly increased the risks of fetal loss (relative risk = 1.14, 95% confidence interval: 1.04, 1.25) and infant death (relative risk = 1.17, 95% confidence interval: 1.03, 1.32). There was a significant dose response of arsenic exposure to risk of infant death (p = 0.02). Women of reproductive age should urgently be prioritized for mitigation activities where drinking water is contaminated by arsenic.",
Arsenic,627519,"Requirement of Erk, but not JNK, for arsenite-induced cell transformation Abstract: Trivalent arsenic (arsenite, As3+) is a human carcinogen, which is associated with cancers of skin, lung, liver, and bladder. However, the mechanism by which arsenite causes cancer is not well understood. In this study, we found that exposure of Cl 41 cells, a well characterized mouse epidermal cell model for tumor promotion, to a low concentration of arsenite (<25 microM) induces cell transformation. Interestingly, arsenite induces Erk phosphorylation and increased Erk activity at doses ranging from 0.8 to 200 microM, while higher doses (more than 50 microM) are required for activation of JNK. Arsenite-induced Erk activation was markedly inhibited by introduction of dominant negative Erk2 into cells, while expression of dominant negative Erk2 did not show inhibition of JNK and MEK1/2. Furthermore, arsenite-induced cell transformation was blocked in cells expressing the dominant negative Erk2. In contrast, overexpression of dominant negative JNK1 was shown to increase cell transformation even though it inhibits arsenite-induced JNK activation. Our results not only show that arsenite induces Erk activation, but also for the first time demonstrates that activation of Erk, but not JNK, by arsenite is required for its effects on cell transformation.",
Arsenic,628333,"Metabolism and excretion of orally and intraperitoneally administered methylarsonic acid in the hamster Abstract: The metabolism and excretion of methylarsonic-acid (124583) (MAA) were studied in hamsters. Male Syrian-Golden-hamsters were administered 0, 5, 50, or 250mg/kg MAA orally or 50mg/kg intraperitoneally (ip). Selected animals were killed before or 1, 6, 12, 24, 72, or 120 hours after dosing and the tissue distribution of inorganic arsenic (7440382), MAA, dimethylarsinic-acid (75605) (DMAA), or trimethylarsenic (593884) was determined. Twenty four hour urine and feces samples were collected before death and analyzed for inorganic arsenic, MAA, DMAA, and trimethylarsenic. Six hours after oral administration, the largest amount of MAA was found in the kidney, followed by spleen, lung, liver, muscle, hair, and brain in that order. MAA concentrations rapidly decreased in all tissues except kidney, only trace amounts being found after 120 hours. MAA concentrations in the kidney decreased very slowly; significant amounts were still present after 120 hours. DMAA was detected in the liver, kidney, lung, and muscle 1 hour after oral dosing; these concentrations peaked at 12 hours. No inorganic arsenic or trimethylarsenic were detected in any tissue. Most of the oral MAA dose was excreted in feces and most of the ip dose was excreted in urine. Less than 0.2 percent of the oral or ip dose was excreted as DMAA in feces. Cumulative DMAA excretion in urine as a percentage of MAA dose was 4.2 percent by the oral route and 1.2 percent by the ip route. The amount of DMAA excreted was not proportional to the MAA dose. Small amounts of trimethylarsenic were excreted in urine. The authors conclude that MAA is unlikely to be methylated or demethylated in-vivo when compared to inorganic arsenic or DMAA.",
Arsenic,62160,"Arsenic and Raynaud's phenomenon: Vasospastic tendency and excretion of arsenic in smelter workers before and after the summer vacation Abstract: Occupational and environmental exposure to inorganic arsenic is associated with the occurrence of Raynaud's phenomenon and objectively registered abnormal finger systolic blood pressure at local cooling (FSP). A subnormal FSP during cooling indicates a vasospastic tendency. It is not known whether these phenomena are related to recent or historical long-term exposure to arsenic. Twenty-one workers from a Swedish smelter were selected on the basis of exposure to arsenic dust for more than 14 years and a previously (three years earlier) recorded subnormal FSP during local cooling. The workers were examined before and after a 4 to 8 week summer vacation. After this intermission in arsenic exposure the urinary excretion of arsenic decreased to normal values, whereas the vasospastic reaction in the fingers remained. Thus the vasospastic tendency seems to be unrelated to the most recent urinary arsenic levels. FSP levels on cooling were significantly increased as compared with the measurements made three years earlier. This suggests a gradual improvement in finger blood circulation caused by decreased exposure to arsenic as evaluated over a time period of several years. The data thus indicate that peripheral vascular disturbances caused by arsenic are dependent on long-term arsenic exposures and are independent of short-term fluctuations in arsenic exposure.",
Arsenic,1453796,"Role of genomic instability in arsenic-induced carcinogenicity: A review Abstract: Exposure to chronic arsenic toxicity is associated with cancer. Although unstable genome is a characteristic feature of cancer cells, the mechanisms leading to genomic instability in arsenic-induced carcinogenesis are poorly understood. While there are excellent reviews relating to genomic instability in general, there is no comprehensive review presenting the mechanisms involved in arsenic-induced genomic instability. This review was undertaken to present the current state of research in this area and to highlight the major mechanisms that may involved in arsenic-induced genomic instability leading to cancer. Genomic instability is broadly classified into chromosomal instability (CIN), primarily associated with mitotic errors; and microsatellite instability (MIN), associated with DNA level instability. Arsenic-induced genomic instability is essentially multi-factorial in nature and involves molecular cross-talk across several cellular pathways, and is modulated by a number of endogenous and exogenous factors. Arsenic and its metabolites generate oxidative stress, which in turn induces genomic instability through DNA damage, irreversible DNA repair, telomere dysfunction, mitotic arrest and apoptosis. In addition to genetic alteration; epigenetic regulation through promoter methylation and miRNA expression alters gene expression profiling leading to genome more vulnerable and unstable towards cancer risk. Moreover, mutations or silencing of pro-apoptotic genes can lead to genomic instability by allowing survival of damaged cells that would otherwise die. Although a large body of information is now generated regarding arsenic-induced carcinogenesis; further studies exploring genome-wide association, role of environment and diet are needed for a better understanding of the arsenic-induced genomic instability.",
Arsenic,2337131,"Arsinous acid as a thiol binding group: potential cysteine peptide tagging functionality that binds a single thiol Abstract: A simple aryl arsinous acid (ArAs(CH3)OH) was prepared by ortho mercuration of p-cresol followed by Pd-catalyzed reaction with methylarsenic dibromide, purification as the mercaptoethanol adduct, and deprotection using a silver salt. Isothermal titration calorimetry experiments showed reaction with mercaptoethanol with an association constant of 6 x 10(4) M-1. Rapid exchange of thiols at the arsenic atom was demonstrated by H-1-NMR.",
Arsenic,2343465,"Arsenic in the Multi-aquifer System of the Mekong Delta, Vietnam: Analysis of Large-Scale Spatial Trends and Controlling Factors Abstract: Groundwater exploitation is rising in the Mekong Delta, Vietnam, potentially exacerbating arsenic contamination from natural sources. We investigate trends and controls on contamination patterns throughout the Delta's multi-aquifer system as observed in a spatially exhaustive data set of arsenic measured in &gt;40,000 wells, 10.5% of which exceed the WHO drinking water standard for arsenic (10 ?g/L). We relate strong trends in the distribution of contamination among well samples to explanatory variables derived from 3D ancillary physicochemical data sets using logistic regression models. Parsimonious models describe much of the observed variability in arsenic occurrence, which differs considerably between subsets of wells tapping shallow versus deeper aquifer groups. In the shallowest Holocene-Pleistocene aquifers, arsenic occurrence is best described by distance to the Mekong river channels and delta front, depth, and location within fault-bounded zones of the region. The same model, however, fails to explain observations in the deeper group of Pliocene-Miocene aquifers. Among these deeper units, arsenic occurrence is rare except among older wells in near-river, heavily pumped areas. Our analysis is the first to examine both natural and anthropogenically mediated contributions to the distribution of arsenic throughout the Mekong Delta's multi-aquifer system, with implications for management of similarly affected basins throughout Southeast Asia.",
Arsenic,1346926,"Establishment of an Invasive Plant Species (Conium maculatum) in Contaminated Roadside Soil in Cook County, Illinois Abstract: ",
Arsenic,1030393,"Enhancement of chromosomal damage by arsenic: implications for mechanism Abstract: Arsenic is a naturally occurring metalloid that has been associated with increased incidence of human cancer in certain highly exposed populations. Arsenic is released to the environment by natural means such as solubilization from geologic formations into water supplies. It is also released to occupational and community environments by such activities as nonferrous ore smelting and combustion of fuels containing arsenic. Several lines of evidence indicate that arsenic acts indirectly with other agents to ultimately enhance specific genotoxic effects that may lead to carcinogenesis. Work described here indicates that arsenite specifically potentiates chromosomal aberrations induced by a DNA crosslinking agent, 1,3-butadiene diepoxide, but does not effect the induction of sister chromatid exchanges under the same treatment conditions. It is proposed that the specific co-clastogenic effects of arsenite seen here may be mediated by its interference with DNA repair activities. Further understanding of the mechanism by which arsenic interacts with other environmental agents will result in more accurate estimates of risk from exposure to arsenic.",
Arsenic,2278040,"Evaluation of seasonal dietary exposure to arsenic, cadmium and lead in schoolchildren through the analysis of meals served by public schools of ribeirão preto, Brazil Abstract: Dietary exposure to arsenic (AS), cadmium (Cd), and lead (Pb) of Brazilian schoolchildren living in Ribeirão Preto, Brazil, was assessed. Food samples including rice, beans, vegetables, fruits, and meat served daily by public schools were collected as presented in different seasons. Metallic elements were determined by inductively coupled plasma-mass spectrometry (ICP-MS).The main sources of As, Cd, and Pb were found to be rice, vegetables, and pork, respectively. Further, in some food types there were seasonal differences in the concentrations of metallic elements. The mean daily intakes of As, Cd, and Pb based upon the association between food consumption data and the observed concentrations of metals in their diet were 6.9 ?g, 0.9 ?g, and 0.6 ?g for As, Cd, and Pb, respectively. These findings are below the toxicological reference values provided by the European Food Safety Authority (EFSA) and the World Health Organization (WHO).",
Arsenic,1508654,"Arsenic present in the soil-vine-wine chain in vineyards situated in an old mining area in Trentino, Italy Abstract: The present study follows arsenic (As) transfer through the chain of soil-vine-leaves-grapes-wine to assess the possible risk of arsenic intake related to consuming grapes and wines produced in 10 vineyards located in a mining area rich in this element. The results are compared with date from 18 uncontaminated areas. In the soil, the content of As extracted with acqua regia and that extracted with ammonium acetate, were analyzed. Leaves and berries were analyzed after washing with acidified aqueous solution and acid mineralization in a closed vessel, whereas wines were simply diluted before analysis. All analyses were performed using an inductively coupled plasma mass-spectrometer. The aqua regia extractable As concentration in soil ranged from 3.7 to 283?mg/kg, whereas available As varied from 18 to 639?µg/kg, and As total concentration ranged from 16.3 to 579?µg/kg dry weight in leaves and from &lt;0.1 to 36.8?µg/kg dry weight in grapes. Arsenic levels in wines were always below 1.62?µg/L, with higher concentration in red wines than in white wines. Significant and positive correlations between the As concentrations in soils, leaves, and berries are highlighted, with the samples collected near the mining area having significantly higher values. Nevertheless, As levels in wines were always well below the limit (200?µg/L) suggested by the International Organization of Vine and Wine.",
Arsenic,1677573,"Multi-element analysis of urine using dynamic reaction cell inductively coupled plasma mass spectrometry (ICP-DRC-MS) - A practical application Abstract: OBJECTIVES: The method for the determination of As, Al, Cd, Ni, Pb (toxic elements) and Cr, Co, Cu, Fe, Mn, Zn (essential elements) in human urine by the use of Inductively Coupled Plasma Mass Spectrometry (quadrupole ICP-MS DRCe Elan, Perkin Elmer) with the dynamic reaction cell (DRC) was developed. MATERIALS AND METHODS: The method has been applied for multi-element analysis of the urine of 16 non-exposed healthy volunteers and 27 workers employed in a copper smelter. The analysis was conducted after initial 10-fold dilution of the urine samples with 0,1% nitric acid. Rhodium was used as an internal standard. The method validation parameters such as detection limit, sensitivity, precision were described for all elements. Accuracy of the method was checked by the regular use of certified reference materials ClinCheck®-Control Urine (Recipe) as well as by participation of the laboratory in the German External Quality Assessment Scheme (G-EQUAS). RESULTS: The detection limits (DL 3s) of the applied method were 0.025, 0.007, 0.002, 0.004, 0.004, 0.086, 0.037, 0.009, 0.016, 0.008, 0.064 (?g/l) for Al, As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, Zn in urine, respectively. For each element linearity with correlation coefficient of at least 0.999 was determined. Spectral interferences from some of the ions were removed using DRC-e with addition of alternative gas: methane for cobalt, copper, cadmium, chromium, iron, manganese, nickel and rhodium, and oxygen for arsenic. CONCLUSIONS: The developed method allows to determine simultaneously eleven elements in the urine with low detection limits, high sensitivity and good accuracy. Moreover, the method is appropriate for the assessment of both environmental and occupational exposure.",
Arsenic,734993,"As4S4 targets RING-type E3 ligase c-CBL to induce degradation of BCR-ABL in chronic myelogenous leukemia Abstract: Arsenic, a curative agent for acute promyelocytic leukemia, induces cell apoptosis and degradation of BCR-ABL in chronic myelogenous leukemia (CML). We demonstrated that ubiquitination and degradation of BCR-ABL was mediated by c-CBL, a RING-type E3 ligase that was also shown to be involved in ubiquitination for many other receptor/protein tyrosine kinases. Our data showed that c-CBL protein was considerably up-regulated by arsenic sulfide (As4S4). Interestingly, arsenic directly bound the RING finger domain of c-CBL to inhibit its self-ubiquitination/degradation without interfering with the enhancement of ubiquitination and subsequent proteolysis of its substrate BCR-ABL. Degradation of BCR-ABL due to c-CBL induction as a result of arsenic treatment was also observed in vivo in CML mice. These findings provide insight into the molecular mechanisms of arsenic and further support its therapeutic applications in CML in combination with tyrosine kinase inhibitors and potentially also in other malignancies involving aberrant receptor/protein tyrosine kinase signaling.",
Arsenic,1015768,"Co-contamination of arsenic and fluoride in the groundwater of unconsolidated aquifers under reducing environments Abstract: The co-contamination of arsenic (As) and fluoride (F(-)) in shallow aquifers is frequently observed worldwide, and the correlations between those contaminants are different according to the redox conditions. This study geochemically explores the reasons for the co-contamination and for the redox-dependent correlations by investigating the groundwater of an alluvial aquifer in Korea. Geochemical signatures of the groundwater in the study area show that the As concentrations are enriched by the reductive dissolution of Fe-(hydr)oxides, and the correlations between As and F(-) concentrations are poor comparatively to those observed in the oxidizing aquifers. However, F(-) concentrations are strongly dependent on pH. Desorption/adsorption experiments using raw soils and citrate-bicarbonate-dithionite treated soils indicated that Fe-(hydr)oxides are the important As and F(-) hosts causing the co-contamination phenomenon. The weaker correlation between F(-) and As in reducing aquifers is likely to be associated with sulfate reduction, which removes As from groundwater without changing the F(-) concentration.",
Arsenic,1519142,EFFECTS OF CADMIUM AND ARSENIC IONS ON CONTENT OF PHOTOSYNTHETIC PIGMENTS IN THE LEAVES OF GLYCINE MAX (L.) MERRILL Abstract: ,
Arsenic,1519185,Quality of autoclave preservative treatment of Eucalyptus grandis and Eucalyptus cloeziana wood Abstract: ,
Arsenic,404776,"Arsenite-enhanced procoagulant activity through phosphatidylserine exposure in platelets Abstract: Numerous epidemiological studies have reported the close relationship between arsenic in drinking water and cardiovascular disease (CVD), yet the exact mechanism underlying this relationship remains unclear. We investigated whether arsenic can affect the procoagulant activity of platelets, which are essential in blood clotting, thrombus formation, and progression of CVD. While arsenite alone did not induce procoagulant activity, it significantly enhanced thrombin-induced procoagulant activity of human platelets in a concentration- and time-dependent manner. In flow cytometric analysis, arsenite potentiated phosphatidylserine (PS) exposure and microparticle (MP) formation, the major mediators of procoagulant activity. Arsenite-enhanced calcium increase and subsequent calpain activation were found to be involved in these effects, as determined by confocal microscopy and gel electrophoresis. Arsenite also inhibited flippase, an enzyme that restores PS to the inner leaflet, suggesting that PS could be retained in outer membranes after exposure. Consistent with these in vitro results, ex vivo studies revealed that PS exposure in platelets was significantly increased after acute or chronic arsenic exposure in rats. Most notably, in a rodent in vivo venous thrombosis model, arsenite indeed led to increased thrombus formation. In conclusion, arsenite-enhanced procoagulant activity in platelets by PS exposure and MP generation ultimately results in accelerated thrombus formation in vivo, suggesting that this enhanced activity is a possible contributing factor in CVD associated with chronic exposure to arsenic through drinking water.",
Arsenic,1508720,"Detection of human papillomavirus genotypes associated with mucopurulent cervicitis and cervical cancer in Changchun, China Abstract: <strong>OBJECTIVE: </strong>To determine the prevalence and genotype distribution of human papillomavirus (HPV) infection among Chinese patients with mucopurulent cervicitis (MPC) or cervical cancer (CC).<br /><br /><strong>METHODS: </strong>In total, 191 cases of CC (n=66), acute MPC (n=84), and healthy cervix controls (n=41) were initially included; samples were collected between May 21, 2008, and October 9, 2011. Cervical specimens were screened for HPV using a nested polymerase chain reaction assay and DNA sequencing.<br /><br /><strong>RESULTS: </strong>Overall prevalence of HPV infection was 20.0% in the control group, 53.3% in the MPC group, and 93.8% in the CC group. The predominant genotype detected in all 3 groups was the oncogenic variant HPV 16 (87.7%, 18.7%, and 10.0% in the CC, MPC and control specimens, respectively). The second most frequent genotype among patients with MPC was HPV 58. This variant is also oncogenic and was detected at a higher rate in the MPC group (9.3%) than in the control (2.5%) and CC (1.5%) groups.<br /><br /><strong>CONCLUSION: </strong>Infection with HPV was prevalent among Chinese women with MPC or CC. Furthermore, the high prevalence of oncogenic genotypes observed among HPV-positive patients with MPC suggests that this group is at increased risk of developing CC.",
Arsenic,2347627,"Estimation of arsenic toxicity by analysis of certain marker enzymes of the air-breathing catfish Clarias batrachus (Linn.) Abstract: In this investigation, Clarias batrachus was exposed to sublethal concentration of sodium arsenite (1mg/L; 5% of LC50 value) for 10, 30, 45, and 60 days. Activities of several enzymes (alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST), glucose-6-phosphate dehydrogenase (G-6-PDH), lipid peroxidase (LPO)) and antioxidant enzymes (reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT)) were monitored in the serum, liver, and muscular tissues. Our results showed a significant increase in the activities of ALP, ALT, AST, and LPO after prolonged exposure of 60 days. Significant decrease in the activities of G-6-PDH, GSH, SOD, and CAT were simultaneously detected after 60 days of exposure. Total protein contents and -SH moieties also decreased significantly after 60 days. Estimation of the activities of these enzymes suggested the severe harmful effect of the trivalent arsenic salt, responsible for tissue damages in the C. batrachus during biochemical analyses.",
Arsenic,1021750,"Mouse arsenic (+3 oxidation state) methyltransferase genotype affects metabolism and tissue dosimetry of arsenicals after arsenite administration in drinking water Abstract: Arsenic (+3 oxidation state) methyltransferase (As3mt) catalyzes methylation of inorganic arsenic (iAs) producing a number of methylated arsenic metabolites. Although methylation has been commonly considered a pathway for detoxification of arsenic, some highly reactive methylated arsenicals may contribute to toxicity associated with exposure to inorganic arsenic. Here, adult female wild-type (WT) C57BL/6 mice and female As3mt knockout (KO) mice received drinking water that contained 1, 10, or 25 ppm (mg/l) of arsenite for 33 days and blood, liver, kidney, and lung were taken for arsenic speciation. Genotype markedly affected concentrations of arsenicals in tissues. Summed concentrations of arsenicals in plasma were higher in WT than in KO mice; in red blood cells, summed concentrations of arsenicals were higher in KO than in WT mice. In liver, kidney, and lung, summed concentrations of arsenicals were greater in KO than in WT mice. Although capacity for arsenic methylation is much reduced in KO mice, some mono-, di-, and tri-methylated arsenicals were found in tissues of KO mice, likely reflecting the activity of other tissue methyltransferases or preabsorptive metabolism by the microbiota of the gastrointestinal tract. These results show that the genotype for arsenic methylation determines the phenotypes of arsenic retention and distribution and affects the dose- and organ-dependent toxicity associated with exposure to inorganic arsenic.",
Arsenic,2347592,"Arsenic pollution of agricultural soils by concentrated animal feeding operations (CAFOs) Abstract: Animal wastes from concentrated animal feeding operations (CAFOs) can cause soil arsenic pollution due to the widespread use of organoarsenic feed additives. This study investigated the arsenic pollution of surface soils in a typical CAFO zone, in comparison with that of agricultural soils in the Pearl River Delta, China. The mean soil arsenic contents in the CAFO zone were elevated compared to those in the local background and agricultural soils of the Pearl River Delta region. Chemical speciation analysis showed that the soils in the CAFO zone were clearly contaminated by the organoarsenic feed additive, p-arsanilic acid (ASA). Transformation of ASA to inorganic arsenic (arsenite and arsenate) in the surface soils was also observed. Although the potential ecological risk posed by the arsenic in the surface soils was relatively low in the CAFO zone, continuous discharge of organoarsenic feed additives could cause accumulation of arsenic and thus deserves significant attention.",
Arsenic,1337656,"Quality of life and mental health status of arsenic-affected patients in a Bangladeshi population Abstract: Contamination of groundwater by inorganic arsenic is one of the major public-health problems in Bangladesh. This cross-sectional study was conducted (a) to evaluate the quality of life (QOL) and mental health status of arsenic-affected patients and (b) to identify the factors associated with the QOL. Of 1,456 individuals, 521 (35.78%) were selected as case and control participants, using a systematic random-sampling method. The selection criteria for cases (n=259) included presence of at least one of the following: melanosis, leucomelanosis on at least 10% of the body, or keratosis on the hands or feet. Control (nonpatient) participants (n=262) were selected from the same villages by matching age (±5 years) and gender. The Bangladeshi version of the WHOQOL-BREF was used for assessing the QOL, and the self-reporting questionnaire (SRQ) was used for assessing the general mental health status. Data were analyzed using Student's t-test and analysis of covariance (ANCOVA), and the WHOQOL-BREF and SRQ scores between the patients and the non-patients were compared. The mean scores of QOL were significantly lower in the patients than those in the non-patients of both the sexes. Moreover, the mental health status of the arsenic-affected patients (mean score for males=8.4 and females=10.3) showed greater disturbances than those of the non-patients (mean score for males=5.2 and females=6.1) of both the sexes. The results of multiple regression analysis revealed that the factors potentially contributing to the lower QOL scores included: being an arsenic-affected patient, having lower age, and having lower annual income. Based on the findings, it is concluded that the QOL and mental health status of the arsenic-affected patients were significantly lower than those of the non-patients in Bangladesh. Appropriate interventions are necessary to improve the well-being of the patients.",
